Degradation Of Vitamin C

The Book
TOC Intro
Chapters:
1 2 3 4 5 6 7 8 9 10 11 12
13 14 15 16 17 18 19 20
21 22 23 24 25
A1 A2 A3 A4 A5 A6 Bib Karl

Vibrant Life Web

Family Of Three Chelation Formulas
Other VL Products
The Wednesday Letter
Frequently Asked Questions
Testimonials

Life Flow One, The Solution For Heart Disease Data Section

Shopping Cart

Use Separate Search Page or

Separate Search Page
or search below

Navigation Help

Ingredients
Technical

Write To Karl Loren

Table Of Contents

EDTA Data

Life Flow One
The Solution For Heart Disease

by
Karl Loren

Degradation Of Vitamin C Studies

Results for your query on March 22, 1999:: Search all fields for: Vitamin C And degradation; Published in 1966 through 1999; Only select references with abstracts available; Show references published in English only; Show references pertaining to humans

Documents: 1 to 100 of 167

Top

Number	Title	Comments
...1...	Factors influencing the stability of ascorbic acid in total parenteral nutrition infusions.
...2...	Ascorbic acid in cholesterol metabolism and in detoxification of xenobiotic substances: problem of optimum vitamin C intake.
...3...	Vitamin C depletion is associated with alterations in blood histamine and plasma free carnitine in adults.
...4...	The reversibility of the vitamin C redox system: electrochemical reasons and biological aspects.
...5...	Ascorbic acid and vitamin B12.
...6...	Vitamin C improves endothelium-dependent vasodilation in patients with insulin-dependent diabetes mellitus.
...7...	Total plasma antioxidant capacity predicts thrombosis-prone status in NIDDM patients.
...8...	Vitamin C improves endothelial function of conduit arteries in patients with chronic heart failure.
...9...	Vitamin C improves endothelium-dependent vasodilation in forearm resistance vessels of humans with hypercholesterolemia.
...10...	Antioxidant vitamin C improves endothelial dysfunction in chronic smokers.
Menu Position #10
...11...	Influence of natural antioxidants on in vitro lipoprotein oxidation.
...12...	Protection by alpha-tocopherol but not ascorbic acid from hydrogen peroxide induced cell death in normal human breast epithelial cells in culture.
...13...	Vitamin C and cardiovascular disease: a review.
...14...	Effect of dietary antioxidant combinations in humans. Protection of LDL by vitamin E but not by beta-carotene.
...15...	Protective effect of alpha-tocopherol and L-ascorbic acid against the ischemic-reperfusion injury in patients during open-heart surgery.
...16...	Gas phase oxidants of cigarette smoke induce lipid peroxidation and changes in lipoprotein properties in human blood plasma. Protective effects of ascorbic acid.
...17...	Nonenzymatic degradation and salvage of dietary folate: physicochemical factors likely to influence bioavailability.
...18...	Adherence, proliferation and collagen turnover by human fibroblasts seeded into different types of collagen sponges.
...19...	Induction of DNA fragmentation in human myelogenous leukemic cell lines by sodium 5,6-benzylidene-L-ascorbate and its related compounds.
...20...	Stability of sodium 5,6-benzylidene-L-ascorbate.
Menu Position #20
...21...	Inhibition of oxidative degradation of hyaluronic acid by uric acid.
...22...	Ascorbate deficiency results in decreased collagen production: under-hydroxylation of proline leads to increased intracellular degradation.
...23...	A critical assessment of the effects of aminoguanidine and ascorbate on the oxidative modification of LDL: evidence for interference with some assays of lipoprotein oxidation by aminoguanidine.
...24...	Bleaching of membrane-bound merocyanine 540 in conjunction with free radical-mediated lipid peroxidation.
...25...	Pentoxifylline. A hydroxyl radical scavenger.	Hydroxyl radical was generated by a mixture of ascorbic acid, H2O2 and Fe(III)-EDTA. We evaluated the iron-dependent degradation of deoxyribose, mediated by hydroxyl radical, in the presence of different concentrations of PTX (from 0.05 to 3 mM), measuring the degradation products of deoxyribose that react with 2-thiobarbituric acid (TBA).
...26...	Ascorbic acid and urate in human seminal plasma: determination and interrelationships with chemiluminescence in washed semen.
...27...	Warfarin causes the degradation of protein C precursor in the endoplasmic reticulum.
...28...	Aggregation and precipitation of human relaxin induced by metal-catalyzed oxidation.	The modification of relaxin by ascorbic acid/CuCl2 solution could be totally inhibited by the presence of EDTA. In contrast, catalase and superoxide dismutase showed no effects on the oxidation process.
...29...	The role of superoxide and hydroxyl radicals in the degradation of hyaluronic acid induced by metal ions and by ascorbic acid.
...30...	Collagen degradation in human lung fibroblasts: extent of degradation, role of lysosomal proteases, and evaluation of an alternate hypothesis.
Menu Position #30
...31...	Biochemical, microbiological, and nutritional aspects of kimchi (Korean fermented vegetable products).
...32...	Retinoic acid-induced inhibition of type I collagen gene expression by human lung fibroblasts.
...33...	Iodine-mediated inactivation of lipid- and nonlipid-enveloped viruses in human antithrombin III concentrate.
...34...	The effect of synovial fluid proteins in the degradation of hyaluronic acid induced by ascorbic acid.	Hyaluronic acid was degraded to less than one-third of the original molecular weight in the range of the physiological concentrations of ascorbic acid. Synovial fluid proteins protected against the ascorbate-dependent degradation of hyaluronic acid at their physiological concentrations. It is suggested that the inhibitory activity of ceruloplasmin mainly depends on the ferroxidase activity and that of transferrin is probably due to iron binding property.
...35...	Modulation by sodium ascorbate of the effect of chloroquine on low density lipoprotein retention and degradation in cultured human skin fibroblasts.
...36...	Measurement of ascorbate and dehydroascorbate contents in biological fluids.
...37...	Ascorbic acid stimulates collagen production without altering intracellular degradation in cultured human skin fibroblasts.
...38...	Lipid peroxidation and haemoglobin degradation in red blood cells exposed to t-butyl hydroperoxide. Effects of the hexose monophosphate shunt as mediated by glutathione and ascorbate.
...39...	Stability of rifampin in plasma: consequences for therapeutic monitoring and pharmacokinetic studies.
...40...	High galactose levels in vitro and in vivo impair ascorbate regeneration and increase ascorbate-mediated glycation in cultured rat lens.
Menu Position #40
...41...	Lack of effect of ascorbic acid, hippuric acid, and methenamine (urinary formaldehyde) on the copper-reduction glucose test in geriatric patients.
...42...	Differing effects of probucol and vitamin E on the oxidation of lipoproteins, ceroid accumulation and protein uptake by macrophages.
...43...	Induction of collagen synthesis by ascorbic acid. A possible mechanism.
...44...	Ascorbate increases the number of low density lipoprotein receptors in cultured arterial smooth muscle cells.
...45...	Bioavailability in infants of iron from infant cereals: effect of dephytinization.
...46...	Fibroblast-migration in a wound model of ascorbic acid-supplemented three-dimensional culture system: the effects of cytokines and malotilate, a new wound healing stimulant, on cell-migration.
...47...	Ascorbic acid specifically increases type I and type III procollagen messenger RNA levels in human skin fibroblast.
...48...	The interaction between two antioxidants, sodium ascorbate and gallic acid: radical intensity and apoptosis induction.
...49...	Regulation of collagen biosynthesis by ascorbic acid: a review.
...50...	In vivo antineoplastic activity of ascorbic acid for human mammary tumor.
Menu Position #50
...51...	Degradation of distinct forms of multimeric vitronectin by human fibroblasts.
...52...	Role of hydrogen peroxide for cell death induction by sodium 5,6-benzylidene-L-ascorbate.
...53...	Effect of physiological fluids on radical intensity of sodium ascorbate and sodium 5,6-benzylidene-L-ascorbate.
...54...	Ultraviolet A decreases epidermal growth factor (EGF) processing in cultured human fibroblasts and keratinocytes: inhibition of EGF-induced diacylglycerol formation.
...55...	Iron deficiency among pregnant Pakistanis in Norway and the content of phytic acid in their diet.
...56...	Iron deficiency among pregnant Pakistanis in Norway and the content of phytic acid in their diet.
...57...	UVA irradiation of human lens proteins produces residual oxidation of ascorbic acid even in the presence of high levels of glutathione.
...58...	Enhancement of cytotoxic activity of ascorbate by Acer nikoense Maxim. Extracts.
...59...	Ascorbic acid promotes prostanoid release in human lung parenchyma.
...60...	Mechanism of interferon-gamma action. Characterization of indoleamine 2,3-dioxygenase in cultured human cells induced by interferon-gamma and evaluation of the enzyme-mediated tryptophan degradation in its anticellular activity.
Menu Position #60
...61...	The effect of ascorbic acid and ferric ammonium citrate on iron uptake and storage in lens epithelial cells.
...62...	Administration of antioxidant vitamins does not alter plasma fibrinolytic activity in subjects with central obesity.
...63...	DNA- and protein-scission activities of ascorbate in the presence of copper ion and a copper-peptide complex.
...64...	Gas chromatographic/mass spectrometric measurement of ascorbic acid and analysis of ascorbic acid degradation in solution.	L-Ascorbic acid, DHA, and the oxidized products derived from AA can be accurately measured using GC/MS. Owing to the complex nature of the reactions through which AA proceeds, we believe that GC/MS is currently the procedure of choice in making AA-related measurements. The methods described are useful in defining reactions involving AA. The methods may indicate in vivo oxidative injury and may allow the use of AA-derived products to determine if antioxidant modulations are effective.
...65...	Ascorbic acid as an antioxidant in measurements of catecholamines in plasma.
...66...	Enhancement of radical intensity and cytotoxic activity of ascorbate by hyperthermia.
...67...	Lack of correlation between TBARS production and PUFA degradation during incubation of membrane erythrocytes in an OH. (Fe2+/H2O2) generator system.
...68...	Ascorbic acid and ferritin catabolism.
...69...	Ability of retinoic and ascorbic acid to interfere with the binding of benzo(a)pyrene to DNA in explants from donors with bronchial cancer.
...70...	Quality control of protein C: protein C synthesized in the presence of warfarin is selectively degraded in the endoplasmic reticulum.
Menu Position #70
...71...	Effect of metal ions on radical intensity and cytotoxic activity of ascorbate.	Various metal ions were investigated for their ability to modify the radical intensity and cytotoxic activity of sodium ascorbate or ascorbic acid. The addition of metal ions, such as Cu+, Cu2+, Fe2+, Zn2+, Mn2+ and Fe3+, dose-dependently enhanced the ascorbyl radical intensity whereas Na+, K+, Ca2+ and Mg2+ were totally inactive. The enhancement of ascorbyl radical intensity by metal ions was tightly coupled with the accelerated degradation of ascorbate. Addition of either serum or albumin significantly reduced the stimulation effect of Cu2+, and almost completely eliminated that of Fe3+ and Zn2+. The noncytotoxic concentration of Cu2+ significantly enhanced the cytotoxicity of ascorbate against cultured human glioblastoma T98G cell line. The present data suggest the possible role of metal ions in the regulation of the biological activity of ascorbate.
...72...	Formation of carbon dioxide from ascorbate in man.
...73...	Enhancement of radical intensity and cytotoxic activity of ascorbate by PSK and lignins.
...74...	Expression and functional characterization of chimeras between human and bovine vitamin-K-dependent protein-S-defining modules important for the species specificity of the activated protein C cofactor activity.
...75...	Role of ascorbate in the activation of NF-kappaB by tumour necrosis factor-alpha in T-cells.
...76...	Effect of ascorbate oxidase on radical intensity and cytotoxic activity of ascorbate.
...77...	Cupric ion/ascorbate/hydrogen peroxide-induced DNA damage: DNA-bound copper ion primarily induces base modifications.	Dialysis of EDTA-treated genomic DNA purified by standard proteinase K digestion/phenol extraction was necessary to remove low molecular weight species, probably transition metal ions and metal ion chelators, which supported frank strand breaks in the presence of ascorbate + H2O2 without supplemental copper ions.
...78...	A randomized, single-blind, placebo-controlled trial of the effects of 200 mg alpha-tocopherol on the oxidation resistance of atherogenic lipoproteins.
...79...	High density lipoprotein subclasses inhibit low density lipoprotein oxidation.
...80...	Abnormally elevated serum transcobalamin II levels in patients with cerebral malaria.
Menu Position #80
...81...	Protection of low density lipoprotein oxidation at chemical and cellular level by the antioxidant drug dipyridamole.
...82...	Antioxidant and prooxidant properties of captopril and enalapril.
...83...	Improvement of some blood coagulation factors in cirrhotic patients treated with low doses of heparin.
...84...	Oxidative structural modifications of low density lipoprotein in homozygous familial hypercholesterolemia.
...85...	Antenatal drugs affecting vitamin K status of the fetus and the newborn.
...86...	Oxidative stress on lens and cataract formation: role of light and oxygen.
...87...	Protein modification by the degradation products of ascorbate: formation of a novel pyrrole from the Maillard reaction of L-threose with proteins.
...88...	Protein C.
...89...	Inactivation of human coagulation factor V by activated protein C.
...90...	Bone mineral density measured by dual-energy x-ray absorptiometry and novel markers of bone formation and resorption in patients on antiepileptic drugs.
Menu Position #90
...91...	Different agonist- and antagonist-induced conformational changes in retinoic acid receptors analyzed by protease mapping.
...92...	Protein C, an antithrombotic protein, is reduced in hospitalized patients with intravascular coagulation.
...93...	Reconstruction of parodontal tissue with chitosan.
...94...	Effect of intravenous calcitriol on secondary hyperparathyroidism in chronic hemodialysis patients.
...95...	Biochemical markers for assessing skeletal growth.
...96...	17-beta estradiol protects neurons from oxidative stress-induced cell death in vitro.
...97...	Investigation of ascorbate-Cu (II) induced cleavage of DNA by scanning tunneling microscopy.
...98...	Determination of serum retinol by reversed-phase high-performance liquid chromatography.
...99...	The stability of retinol, alpha-tocopherol, trans-lycopene, and trans-beta-carotene in liquid-frozen and lyophilized serum.
...100...	Vitamin D metabolism in human colon adenocarcinoma-derived Caco-2 cells: expression of 25-hydroxyvitamin D3-1alpha-hydroxylase activity and regulation of side-chain metabolism.

Menu Position #100

NLM database Documents

Record 1 from database: MEDLINE
Return To Top

Title: Factors influencing the stability of ascorbic acid in total parenteral nutrition infusions.
Author: Allwood MC
Address
Source: J Clin Hosp Pharm, 1984 Jun, 9:2, 75-85
Abstract: Ascorbic acid stability in TPN infusions in 3-litre plastic bags was examined. Vitamin C was found to degrade slowly in mixtures which do not contain trace elements. In the presence of copper, degradation proceeds rapidly until dissolved oxygen is depleted. Reducing the copper concentration had only a minor influence on degradation rate. However, this copper-catalyzed reaction was prevented if cysteine was present in the TPN regimen. The amount of ascorbic acid degraded depended on the dissolved oxygen content of the infusion, the amount of residual air in the bag after filling and the permeability of the plastic to oxygen. In the absence of copper, 20-30 mg ascorbic acid was broken down within 24 h at ambient temperatures, but if copper was present, 150-200 mg was degraded within 2-4 h. The contribution of dehydroascorbic acid to the amount of vitamin C delivered to the patient was negligible. It is concluded that either vitamin C and trace element injections containing copper should not be added to the same bag, or an adequate coverage of ascorbic acid must be included to allow for losses by oxidation before and during administration.
Language of Publication: English
Unique Identifier: 84265330

Return To Top

MeSH Heading (Major): Ascorbic Acid|AD/*ME/PD; Parenteral Nutrition|*/AE; Parenteral Nutrition, Total|*/AE
MeSH Heading: Cold; Copper|PD; Cysteine|PD; Dehydroascorbic Acid|ME; Drug Packaging; Drug Stability; Drug Storage; Human; Oxygen|AN/PD; Plastics|PD; Solutions

Publication Type: JOURNAL ARTICLE
ISSN: 0143-3180
Country of Publication: ENGLAND

Record 2 from database: MEDLINE
Return To Top

Title: Ascorbic acid in cholesterol metabolism and in detoxification of xenobiotic substances: problem of optimum vitamin C intake.
Author: Ginter E
Address: Research Institute of Human Nutrition, Bratislava, Czechoslovakia.
Source: Nutrition, 1989 Nov, 5:6, 369-74
Abstract: There are extreme contradictions in the question of an optimum intake of vitamin C. The Recommended Dietary Allowances (RDA) in the USA, Great Britain, and many other countries range from 30 to 60mg for an adult man or woman, whereas the proponents of megadoses recommend as much as 18,000mg per day. Critical opinions against both the official RDA and the hypothesis of megadoses are summarized. Ideal RDA should be based on studies with increasing vitamin C doses in which the efficiency of the ascorbate-dependent systems would be correlated with the vitamin C concentration in the target tissues. On the basis of correlations of the hepatic vitamin C levels in guinea pigs with the rate of cholesterol degradation and the activity of microsomal detoxification systems, it is suggested that such intake of ascorbic acid is optimum that ensures a maximum body pool and maximum steady-state levels of vitamin C in the tissues. It is probable that in healthy adults, such a dose ranges from 100 to 200mg and that in stress conditions, it exceeds 200mg per day.
Language of Publication: English
Unique Identifier: 92199820

Return To Top

MeSH Heading (Major): Ascorbic Acid|*AD/ME
MeSH Heading: Animal; Ascorbic Acid Deficiency|DT/ME; Cholesterol|ME; Cytochrome P-450|ME; Human; Metabolic Detoxication, Drug; Nutritional Requirements; Stress|DT/ME; Xenobiotics|ME

Publication Type: JOURNAL ARTICLE; REVIEW; REVIEW, TUTORIAL
ISSN: 0899-9007
Country of Publication: UNITED STATES

Record 3 from database: MEDLINE
Return To Top

Title: Vitamin C depletion is associated with alterations in blood histamine and plasma free carnitine in adults.
Author: Johnston CS; Solomon RE; Corte C
Address: Department of Family Resources and Human Development, Arizona State University, Tempe 85287-2502, USA.
Source: J Am Coll Nutr, 1996 Dec, 15:6, 586-91
Abstract: OBJECTIVE: The purpose of this study was to determine whether carnitine metabolism or histamine degradation would be useful parameters for investigating the optimal requirement for vitamin C. METHODS: Twenty-two non-scorbutic subjects with subnormal vitamin C status (plasma vitamin C < 28 mumol/L) were placed on a metabolic diet low in vitamin C for 3 weeks and repleted with graded doses of vitamin C: 10, 30 and 60 mg vitamin C daily (group 1) or 10,125 and 250 mg vitamin C daily (group 2) for weeks 1, 2 and 3, respectively. Fasting blood samples were collected weekly and analyzed for plasma vitamin C, plasma free carnitine and blood histamine. RESULTS: Group 1 subjects remained in a subnormal vitamin C state throughout the 3-week study, and blood histamine and plasma free carnitine were not impacted by the experimental treatment. Plasma vitamin C in group 2 subjects rose significantly during the study, and these subjects finished the study with an ample vitamin C status indicative of vitamin C intakes above the recommended dietary allowance. Both blood histamine and plasma free carnitine were inversely related to vitamin C status in group 2 subjects. CONCLUSIONS: These data indicate that blood histamine and plasma free carnitine are altered in individuals with subnormal, non-scorbutic vitamin C status and provide evidence that metabolic changes independent of collagen metabolism occur prior to the manifestation of scurvy. Thus utilizing scurvy as an end-point to determine vitamin C requirements may not provide adequate vitamin C to promote optimal health and well-being.
Language of Publication: English
Unique Identifier: 97109456

Return To Top

MeSH Heading (Major): Ascorbic Acid Deficiency|*BL/UR; Histamine|*BL
MeSH Heading: Adult; Ascorbic Acid|AD/BL/UR; Carnitine|BL; Female; Human; Male; Scurvy|BL; Support, Non-U.S. Gov't

Publication Type: JOURNAL ARTICLE
ISSN: 0731-5724
Country of Publication: UNITED STATES

Record 4 from database: MEDLINE
Return To Top

Title: The reversibility of the vitamin C redox system: electrochemical reasons and biological aspects.
Author: Sapper H; Kang SO; Paul HH; Lohmann W
Address
Source: Z Naturforsch [C], 1982 Oct, 37:10, 942-6
Abstract: The biological efficacy of vitamin C depends on its redox abilities as given by the relations between ascorbic acid, semidehydroascorbic acid, and dehydroascorbic acid. It is shown by means of proton magnetic resonance spectroscopy that the enzymatic (by ascorbate oxidase) as well as non-enzymatic (by iodine) oxidation of ascorbic acid is, in principle, reversible despite the hydration and structural changes during the formation of dehydroascorbic acid. The strong redox activity of semidehydroascorbic acid which results in a fast disproportionation to ascorbic acid and dehydroascorbic acid is inferred from an inversion of the electrochemical potentials of the vitamin C redox system. The capacity of this is maintained by a fast reduction of dehydroascorbic acid e.g. by reduced glutathione, preventing its delactonization and further degradation.
Language of Publication: English
Unique Identifier: 83095669

Return To Top

MeSH Heading (Major): Ascorbic Acid|BL/*ME
MeSH Heading: Animal; Ascorbate Oxidase|ME; Dehydroascorbic Acid; Glutathione; Human; Nuclear Magnetic Resonance; Oxidation-Reduction

Publication Type: JOURNAL ARTICLE
Country of Publication: GERMANY, WEST

Record 5 from database: MEDLINE
Return To Top

Title: Ascorbic acid and vitamin B12.
Author: Newmark HL; Scheiner JM; Marcus M; Prabhudesai M
Address
Source: JAMA, 1979 Nov, 242:21, 2319-20
Abstract: Using extraction procedures in which the extracted vitamin B12 was protected by cyanide or metabisulfite, several investigators found no change in vitamin B12 when meals were incubated in the presence of ascorbic acid for 30 minutes at 37 degrees C. A previous report suggested degradation of vitamin B12 under these conditions, but this was apparently caused by incomplete protection of the extracted vitamin B12 in the assay procedure. If incubation at 37 degrees C for 30 minutes is a laboratory mimic of the gastric environment, one must conclude that high doses of ascorbic acid do not affect the stability of vitamin B12 in vivo.
Language of Publication: English
Unique Identifier: 80029992

Return To Top

MeSH Heading (Major): Ascorbic Acid|AE/*AN; Food Analysis|*/MT; Vitamin B 12|AI/*AN/ME
MeSH Heading: Human

Publication Type: JOURNAL ARTICLE
ISSN: 0098-7484
Country of Publication: UNITED STATES

Record 6 from database: MEDLINE
Return To Top

Title: Vitamin C improves endothelium-dependent vasodilation in patients with insulin-dependent diabetes mellitus.
Author: Timimi FK; Ting HH; Haley EA; Roddy MA; Ganz P; Creager MA
Address: Cardiovascular Division, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA.
Source: J Am Coll Cardiol, 1998 Mar, 31:3, 552-7
Abstract: OBJECTIVES: We sought to determine whether the antioxidant vitamin C improves endothelium-dependent vasodilation of forearm resistance vessels in patients with insulin-dependent diabetes mellitus. BACKGROUND: Endothelium-dependent vasodilation is impaired in patients with diabetes mellitus. Oxidatively mediated degradation of endothelium-derived nitric oxide contributes to abnormal endothelium-dependent vasodilation in animal models of diabetes mellitus. METHODS: The study group included 10 patients with insulin-dependent diabetes mellitus and 10 age-matched control subjects. Forearm blood flow was determined by venous occlusion plethysmography. Endothelium-dependent vasodilation was assessed by intraarterial infusion of methacholine (0.3 to 10 microg/min). Endothelium-independent vasodilation was assessed by intraarterial infusion of nitroprusside (0.3 to 10 microg/min). Forearm blood flow dose-response curves were determined for each drug infusion before and during concomitant infusion of vitamin C (24 mg/min). RESULTS: In diabetic subjects, endothelium-dependent vasodilation was augmented by the concomitant infusion of vitamin C (p = 0.001). Endothelium-independent vasodilation was not affected by the concomitant infusion of vitamin C (p = NS). In control subjects, vitamin C infusion did not affect endothelium-dependent vasodilation (p = NS). CONCLUSIONS: Vitamin C selectively restores the impaired endothelium-dependent vasodilation in the forearm resistance vessels of patients with insulin-dependent diabetes mellitus. These findings indicate that nitric oxide degradation by oxygen-derived free radicals contributes to abnormal vascular reactivity in humans with insulin-dependent diabetes mellitus.
Language of Publication: English
Unique Identifier: 98161741

Return To Top

MeSH Heading (Major): Ascorbic Acid|AD/*PD; Diabetes Mellitus, Insulin-Dependent|*PP; Endothelium, Vascular|*DE/PP; Free Radical Scavengers|AD/*PD; Vascular Resistance|*DE; Vasodilation|*DE
MeSH Heading: Adult; Drug Administration Schedule; Female; Forearm|BS; Human; Infusions, Intra-Arterial; Male; Middle Age; Support, U.S. Gov't, P.H.S.; Treatment Outcome

Publication Type: JOURNAL ARTICLE
ISSN: 0735-1097
Country of Publication: UNITED STATES

Record 7 from database: MEDLINE
Return To Top

Title: Total plasma antioxidant capacity predicts thrombosis-prone status in NIDDM patients.
Author: Ceriello A; Bortolotti N; Pirisi M; Crescentini A; Tonutti L; Motz E; Russo A; Giacomello R; Stel G; Taboga C
Address: Department of Medicine and Pathology, Clinical and Experimental, University of Udine, Italy.
Source: Diabetes Care, 1997 Oct, 20:10, 1589-93
Abstract: OBJECTIVE: To explore the hypothesis that a relationship exists between free radical activity and abnormalities in hemostasis in NIDDM. RESEARCH DESIGN AND METHODS: The use of the total radical-trapping antioxidant parameter (TRAP) has very recently been proposed to explore the antioxidant property of a plasma and their mutual cooperation. In the present study, TRAP, vitamin E, vitamin C, vitamin A, uric acid, protein-bound SH (thiol) groups, fibrinogen, prothrombin fragments F1 + 2, and D-dimer have been evaluated in 46 NIDDM patients and 47 healthy matched control subjects. RESULTS: In NIDDM patients, TRAP, vitamin A, SH groups, and uric acid were significantly reduced, whereas the level of vitamin E was significantly increased. Vitamin C was similar in the two groups. Fibrinogen, prothrombin fragment 1 + 2, and D-dimer were increased in diabetic patients. TRAP, but no single other antioxidant, had a strong inverse association with fibrinogen, prothrombin fragment 1 + 2, and D-dimer. CONCLUSIONS: These findings are consistent with the hypothesis that oxidative stress may condition coagulation activation in diabetics. However, the data suggest that it is the total antioxidant capacity rather than any single plasma antioxidant that is the most relevant parameter.
Language of Publication: English
Unique Identifier: 97460215

Return To Top

MeSH Heading (Major): Antioxidants|*AN; Diabetes Mellitus, Non-Insulin-Dependent|*BL; Diabetic Angiopathies|*EP; Thrombosis|*EP
MeSH Heading: Ascorbic Acid|BL; Case-Control Studies; Female; Fibrin Fibrinogen Degradation Products|AN; Fibrinogen|AN; Hemostasis; Human; Male; Middle Age; Peptide Fragments|AN; Predictive Value of Tests; Protein Precursors|AN; Prothrombin|AN; Reference Values; Regression Analysis; Risk Factors; Uric Acid|BL; Vitamin A|BL; Vitamin E|BL

Publication Type: JOURNAL ARTICLE
ISSN: 0149-5992
Country of Publication: UNITED STATES

Record 8 from database: MEDLINE
Return To Top
Return To Menu Position #10

Title: Vitamin C improves endothelial function of conduit arteries in patients with chronic heart failure.
Author: Hornig B; Arakawa N; Kohler C; Drexler H
Address: Abteilung Kardiologie, Medizinische Hochschule Hannover, Germany.
Source: Circulation, 1998 Feb, 97:4, 363-8
Abstract: BACKGROUND: Chronic heart failure (CHF) is associated with endothelial dysfunction including impaired endothelium-mediated, flow-dependent dilation (FDD). There is evidence for increased radical formation in CHF, raising the possibility that nitric oxide is inactivated by radicals, thereby impairing endothelial function. To test this hypothesis, we determined the effect of the antioxidant vitamin C on FDD in patients with CHF. METHODS AND RESULTS: High-resolution ultrasound and Doppler was used to measure radial artery diameter and blood flow in 15 patients with CHF and 8 healthy volunteers. Vascular effects of vitamin C (25 mg/min IA) and placebo were determined at rest and during reactive hyperemia (causing endothelium-mediated dilation) before and after intra-arterial infusion of N-monomethyl-L-arginine (L-NMMA) to inhibit endothelial synthesis of nitric oxide. Vitamin C restored FDD in patients with heart failure after acute intra-arterial administration (13.2+/-1.7% versus 8.2+/-1.0%; P<.01) and after 4 weeks of oral therapy (11.9+/-0.9% versus 8.2+/-1.0%; P<.05). In particular, the portion of FDD mediated by nitric oxide (ie, inhibited by L-NMMA) was increased after acute as well as after chronic treatment (CHF baseline: 4.2+/-0.7%; acute: 9.1+/-1.3%; chronic: 7.3+/-1.2%; normal subjects: 8.9+/-0.8%; P<.01). CONCLUSIONS: Vitamin C improves FDD in patients with CHF as the result of increased availability of nitric oxide. This observation supports the concept that endothelial dysfunction in patients with CHF is, at least in part, due to accelerated degradation of nitric oxide by radicals.
Language of Publication: English
Unique Identifier: 98127728

Return To Top
Return To Menu Position #10

MeSH Heading (Major): Ascorbic Acid|AD/*TU; Cardiac Output, Low|*DT/PP/US; Endothelium, Vascular|*DE/*PP/US; Radial Artery|*DE/*PP/US
MeSH Heading: omega-N-Methylarginine|PD; Administration, Oral; Adult; Chronic Disease; Enzyme Inhibitors|PD; Human; Injections, Intra-Arterial; Male; Middle Age; Regional Blood Flow|DE/PH; Support, Non-U.S. Gov't; Time Factors; Treatment Outcome; Vasodilation|DE/PH

Publication Type: CLINICAL TRIAL; JOURNAL ARTICLE
ISSN: 0009-7322
Country of Publication: UNITED STATES

Record 9 from database: MEDLINE
Return To Top
Return To Menu Position #10

Title: Vitamin C improves endothelium-dependent vasodilation in forearm resistance vessels of humans with hypercholesterolemia.
Author: Ting HH; Timimi FK; Haley EA; Roddy MA; Ganz P; Creager MA
Address: Vascular Medicine and Atherosclerosis Unit, Brigham and Women's Hospital, Boston, MA 02115, USA.
Source: Circulation, 1997 Jun, 95:12, 2617-22
Abstract: BACKGROUND: Endothelium-dependent vasodilation is impaired in humans with hypercholesterolemia. Oxidative degradation of endothelium-derived nitric oxide plays a major role in endothelial dysfunction in animal models of hypercholesterolemia. To assess whether this mechanism is relevant to humans, we studied the effect of vitamin C, an antioxidant, on vasodilator function in forearm resistance vessels of patients with hypercholesterolemia. METHODS AND RESULTS: We studied 11 hypercholesterolemic and 12 healthy control subjects. Forearm blood flow was determined by venous occlusion plethysmography. Endothelium-dependent vasodilation was assessed by intra-arterial infusion of methacholine (0.3 to 10 micrograms/min). Endothelium-independent vasodilation was measured by intra-arterial infusion of nitroprusside (0.3 to 10 micrograms/min) and verapamil (10 to 300 micrograms/min). Forearm blood flow dose-response curves were determined for each drug before and during coadministration of vitamin C (24 mg/min). In hypercholesterolemic subjects, endothelium-dependent vasodilation to methacholine was augmented by coinfusion of vitamin C (P = .001); in contrast, endothelium-independent vasodilation to nitroprusside and verapamil were not affected by coinfusion of vitamin C (P = .8 and P = .3, respectively). In control subjects, vitamin C administration did not alter endothelium-dependent vasodilation (P = .2). CONCLUSIONS: We conclude that vitamin C improves endothelium-dependent vasodilation in the forearm resistance vessels of patients with hypercholesterolemia. These findings suggest that nitric oxide degradation by oxygen-derived free radicals contributes to abnormal vascular reactivity in hypercholesterolemic humans.
Language of Publication: English
Unique Identifier: 97336682

Return To Top
Return To Menu Position #10

MeSH Heading (Major): Ascorbic Acid|*TU; Endothelium, Vascular|*PP; Forearm|*BS; Hypercholesterolemia|*DT/*PP; Vascular Resistance|*; Vasodilation|*DE
MeSH Heading: Adult; Female; Human; Male; Middle Age; Regional Blood Flow|DE; Support, Non-U.S. Gov't; Support, U.S. Gov't, P.H.S.; Vehicles|PD

Publication Type: CLINICAL TRIAL; JOURNAL ARTICLE
ISSN: 0009-7322
Country of Publication: UNITED STATES

Record 10 from database: MEDLINE
Return To Top
Return To Menu Position #10

Title: Antioxidant vitamin C improves endothelial dysfunction in chronic smokers.
Author: Heitzer T; Just H; Münzel T
Address: Medizinische Klinik III, Kardiologie, UniversitÂat Freiburg, Germany.
Source: Circulation, 1996 Jul, 94:1, 6-9
Abstract: BACKGROUND: Chronic smoking is associated with endothelial dysfunction, an early stage of atherosclerosis. It has been suggested that endothelial dysfunction may be a consequence of enhanced degradation of nitric oxide secondary to formation of oxygen-derived free radicals. To test this hypothesis, we investigated the effects of the antioxidant vitamin C on endothelium-dependent responses in chronic smokers. METHODS AND RESULTS: Forearm blood flow responses to the endothelium-dependent vasodilator acetylcholine (7.5, 15, 30, and 60 micrograms/min) and the endothelium-independent vasodilator sodium nitroprusside (1, 3, and 10 micrograms/min) were measured by venous occlusion plethysmography in 10 control subjects and 10 chronic smokers. Drugs were infused into the brachial artery, and forearm blood flow was measured for each drug before and during concomitant intra-arterial infusion of the antioxidant vitamin C (18 mg/min). In control subjects, vitamin C had no effect on forearm blood flow in response to acetylcholine and sodium nitroprusside. In contrast, in chronic smokers the attenuated forearm blood flow responses to acetylcholine were markedly improved by concomitant administration of vitamin C, whereas the vasodilator responses to sodium nitroprusside were not affected. CONCLUSIONS: The present studies demonstrate that the antioxidant vitamin C markedly improves endothelium-dependent responses in chronic smokers. This observation supports the concept that endothelial dysfunction in chronic smokers is at least in part mediated by enhanced formation of oxygen-derived free radicals.
Language of Publication: English
Unique Identifier: 96266946

Return To Top
Return To Menu Position #10

MeSH Heading (Major): Antioxidants|*TU; Ascorbic Acid|*TU; Endothelium, Vascular|*DE/*PP; Smoking|*AE
MeSH Heading: Acetylcholine|TU; Forearm|BS; Human; Injections, Intra-Arterial; Middle Age; Nitroprusside|TU; Reference Values; Regional Blood Flow|DE; Time Factors

Publication Type: CLINICAL TRIAL; JOURNAL ARTICLE
ISSN: 0009-7322
Country of Publication: UNITED STATES

Record 11 from database: MEDLINE
Return To Top
Return To Menu Position #10

Title: Influence of natural antioxidants on in vitro lipoprotein oxidation.
Author: Dobreanu M; Módy E
Address: Department of Clinical Biochemistry-Laboratory, TÈargu-MureÀs University of Medicine and Pharmacy, Romania.
Source: Rom J Intern Med, 1997 Jan, 35:1-4, 55-62
Abstract: Susceptibility of low-density lipoproteins (LDL) to oxidation might be a critical risk factor in the development and progression of atherosclerosis. The oxidation involves the degradation of polyunsaturated fatty acids, the formation of lysolecithin, oxysterols and aldehyde modification of lysine residues on Apo B100. The oxidation products have a number of biological activities such as cytotoxicity, atherogenesis, and carcinogenesis. The aim of this study was to investigate the in vitro antioxidant effects of vitamins E, A, and C on LDL. LDL was isolated from plasma by density gradient high-speed centrifugation and used as 0.1 microM/l isotonic solution. LDL oxidation was triggered by simple incubation with Cu2+ (1, 2, 5, 10, 12, 20 microM/l), in absence or presence of lipid-soluble or water-soluble antioxidants in different concentrations (tocopherols--0.5, 1, 2, and 4 microM/l; cerotenoids--0.1, 0.2, and 0.4 microM/l; ascorbate--2.5, 5, and 10 microM/l). The LDL oxidability was measured by continuous spectrophotometrical monitoring at 234 nm of the increased formation of conjugated diene hydroperoxides. The oxidation curves showed a profile with an inhibition period followed by a propagation period and were quantitatively characterized by two parameters: lag-phase (expressed in minutes), and propagation rate (expressed in changes of absorbance--delta E234nm/min). Lag-phase--the period of inhibition oxidation--was attributed to the ability of LDL (by antioxidants) to resist oxidation in vitro. LDL lag-phase decreased and propagation rate increased with the increasing of copper concentration. In conclusion: 1) susceptibility of LDL to oxidation depends on both the concentration of pro-oxidant stimuli and the entity and concentrations of antioxidants; 2) antioxidants retard the process through which LDL undergo oxidation in vitro when exposed to copper ions; 3) a synergistic effect may also be involved, as water-soluble vitamin C keeps the fat-soluble vitamin E and vitamin A within LDL.
Language of Publication: English
Unique Identifier: 98223746

Return To Top
Return To Menu Position #10

MeSH Heading (Major): Antioxidants|*PD; Lipid Peroxidation|*DE; Lipoproteins, LDL|*DE/IP/ME
MeSH Heading: Ascorbic Acid|PD; Comparative Study; Copper|PD; Dose-Response Relationship, Drug; Human; In Vitro; Isotonic Solutions; Time Factors; Vitamin A|PD; Vitamin E|PD

Publication Type: JOURNAL ARTICLE
ISSN: 1220-4749
Country of Publication: ROMANIA

Record 12 from database: MEDLINE
Return To Top
Return To Menu Position #10

Title: Protection by alpha-tocopherol but not ascorbic acid from hydrogen peroxide induced cell death in normal human breast epithelial cells in culture.
Author: Dabrosin C; Ollinger K
Address: Department of Obstetrics and Gynaecology, Faculty of Health Sciences, University Hospital, LinkÂoping, Sweden. lotda@ihm.liu.se
Source: Free Radic Res, 1998 Sep, 29:3, 227-34
Abstract: Alpha-tocopherol and ascorbic acid have been suggested to play a role in breast cancer prevention due to their antioxidative capacity. Increased exposure to endogenous and exogenous sex steroids is a known risk factor for breast cancer. We have studied the effects of alpha-tocopherol and ascorbic acid on hydrogen peroxide induced cell death in sex hormone treated normal breast epithelial cells in culture. We found that alpha-tocopherol but not ascorbic acid alone protected the cells. The effect of alpha-tocopherol increased when ascorbic acid was added to the cultures. The hydrogen peroxide degradation rate decreased in cultures treated with alpha-tocopherol alone and in combination with ascorbic acid compared to cells grown in medium or with ascorbic acid only. Oestradiol and progesterone treatment did not influence the results. Possible beneficial effects of combining various antioxidants, endogenous as well as exogenous, on human breast tissue need to be investigated further both in vivo and in vitro.
Language of Publication: English
Unique Identifier: 99017540

Return To Top
Return To Menu Position #10

MeSH Heading (Major): Ascorbic Acid|AN/*PD; Breast|*CY/DE; Epithelial Cells|*DE; Hydrogen Peroxide|ME/*TO; Vitamin E|AN/*PD
MeSH Heading: Cell Death|DE; Cells, Cultured; Estradiol|PD; Female; Human; Lactate Dehydrogenase|ME; Progesterone|PD; Support, Non-U.S. Gov't

Publication Type: JOURNAL ARTICLE
ISSN: 1071-5762
Country of Publication: SWITZERLAND

Record 13 from database: MEDLINE
Return To Top
Return To Menu Position #10

Title: Vitamin C and cardiovascular disease: a review.
Author: Simon JA
Address: Prevention Sciences Group of the University of California, San Francisco, School of Medicine.
Source: J Am Coll Nutr, 1992 Apr, 11:2, 107-25
Abstract: Vitamin C functions as a regulator of the catabolism of cholesterol to bile acids in the guinea pig and has been demonstrated to be an important factor in lipid regulation of the guinea pig, rabbit and rat. Correlation studies in humans have shown an inverse relationship between vitamin C intake and cardiovascular disease mortality. Observational and experimental studies in humans have yielded inconsistent results, but taken together indicate that for individuals with high total cholesterol concentrations, greater than or equal to 5.20 mmol/L (200 mg/dl) and less than full tissue saturation, increasing the concentration of vitamin C may have a salutary effect on total cholesterol. Vitamin C's effect on promoting the production and inhibiting the degradation of prostacyclin is reviewed, as are implications of these findings regarding thrombosis and atherogenesis. Evidence indicative of a protective effect on lipid peroxidation by vitamin C is examined. Analysis of the literature regarding groups at high risk for coronary heart disease reveals that men, the elderly, smokers, diabetics, hypertensives and perhaps oral estrogen-containing contraceptive users have lowered plasma vitamin C levels. Evidence linking vitamin C to human cardiovascular disease is largely circumstantial, but taken in total, is suggestive of an association. Further examination of the relationship between vitamin C and cardiovascular disease is warranted.
Language of Publication: English
Unique Identifier: 92251056

Return To Top
Return To Menu Position #10

MeSH Heading (Major): Ascorbic Acid|*PH/TU; Cardiovascular Diseases|ET/*PC; Cholesterol|*ME
MeSH Heading: Animal; Blood Pressure; Hemostasis; Human; Lipid Peroxidation; Risk Factors

Publication Type: JOURNAL ARTICLE; REVIEW; REVIEW, ACADEMIC
ISSN: 0731-5724
Country of Publication: UNITED STATES
CAS Registry/EC Number: 50-81-7 (Ascorbic Acid); 57-88-5 (Cholesterol)

Record 14 from database: MEDLINE
Return To Top
Return To Menu Position #10

Title: Effect of dietary antioxidant combinations in humans. Protection of LDL by vitamin E but not by beta-carotene.
Author: Reaven PD; Khouw A; Beltz WF; Parthasarathy S; Witztum JL
Address: Department of Medicine, University of California, San Diego, La Jolla 92093-0682.
Source: Arterioscler Thromb, 1993 Apr, 13:4, 590-600
Abstract: Experimental and epidemiological evidence supports the hypothesis that oxidation of low density lipoprotein (LDL) appears to be important in mediating the atherogenicity of LDL. To test this hypothesis in humans, it will be necessary to perform intervention studies in large populations. We performed two studies to assess the effectiveness of supplementation with beta-carotene and vitamin E, used alone and in combination with each other, and with vitamin C, to protect LDL from oxidation. In phase 1, after a placebo period, eight subjects were given beta-carotene (60 mg/day) for 3 months, then beta-carotene plus vitamin E (1,600 mg/day) for another 3 months, and then beta-carotene plus vitamin E plus vitamin C (2 g/day) for 3 months. During phase 2, beta-carotene and vitamin C were discontinued, and subjects took only vitamin E for 5 months. During each period, LDL samples were isolated, and measurements of susceptibility to oxidation were performed. beta-Carotene levels in LDL increased nearly 20-fold, but LDL susceptibility to oxidation did not change. Addition of vitamin E increased LDL vitamin E levels nearly 2.5-fold, and this decreased LDL oxidation 30-40%. During the vitamin C supplementation period, plasma levels of beta-carotene and vitamin E rose, but only beta-carotene increased in LDL. However, the susceptibility of LDL to oxidation in this period was not decreased further. During phase 2, when subjects took only vitamin E, LDL susceptibility to oxidation was decreased by 50% as measured by thiobarbituric acid-reactive substances, conjugated dienes, and lipid peroxide formation as well as by macrophage degradation. Thus, long-term supplementation with large doses of vitamin E alone, but not beta-carotene, conferred increased protection to LDL in in vitro assays of oxidation. These data should be useful in planning therapeutic strategies to test the antioxidant hypothesis in humans.
Language of Publication: English
Unique Identifier: 93222138

Return To Top
Return To Menu Position #10

MeSH Heading (Major): Carotene|*PD; Lipoproteins, LDL|*ME; Oxidation-Reduction|*/DE; Vitamin E|*PD
MeSH Heading: Adult; Aged; Ascorbic Acid|PD; Diet; Drug Combinations; Female; Human; Macrophages|ME; Male; Middle Age; Support, Non-U.S. Gov't; Support, U.S. Gov't, P.H.S.; Thiobarbituric Acid Reactive Substances|ME

Publication Type: JOURNAL ARTICLE
ISSN: 1049-8834
Country of Publication: UNITED STATES
CAS Registry/EC Number: 0 (Drug Combinations); 0 (Lipoproteins, LDL); 0 (Thiobarbituric Acid Reactive Substances); 1406-18-4 (Vitamin E); 36-88-4 (Carotene); 50-81-7 (Ascorbic Acid); 7235-40-7 (Beta Carotene)

Record 15 from database: MEDLINE
Return To Top
Return To Menu Position #10

Title: Protective effect of alpha-tocopherol and L-ascorbic acid against the ischemic-reperfusion injury in patients during open-heart surgery.
Author: Barta E; Pechán I; Cornák V; Luknárová O; Rendeková V; Verchovodko P
Address: Institute for Cardiovascular Diseases, Medical Faculty, Comenius University, Bratislava, CSFR.
Source: Bratisl Lek Listy, 1991 Mar-Apr, 92:3-4, 174-83
Abstract: The purpose of the investigation was: 1. to examine the effect of cardiopulmonary bypass (CPB) on the generation of cytotoxic oxygen-derived radicals and 2. to determine if the pretreatment of patients with vitamins E and C will combat generation of such radicals. Twenty patients undergoing CPB for treatment of cardiac disease were entered into the study and randomized to one of two groups. Group 1 (n = 9) served as control. Group 2 (n = 11) consisted of patients pretreated with 2000 IU of vitamin E 12 h prior to surgical intervention and 2 g of vitamin C given in the morning on the day of operation. Blood samples from arterial and mixed venous blood for analysis were obtained at the following intervals: 1. before anesthesia, 2. before sternotomy, 3. at the start of CPB, 4. at the end of CPB, 5. at the time of skin closure, 6. in the morning of the following day. Blood specimens from the coronary sinus were withdrawn A--before aortic cross-clamping, B--immediately after aortic declamping, C--in the 5th min, and D--in the 15th min of reperfusion. The concentration of inorganic phosphate as well as of uric acid was significantly higher in the control group what might indicate that vitamins E and C attenuate the degradation of adenine nucleotides. The most important difference between treated and control groups was observed in plasma concentration of malondialdehyde--a marker of lipid peroxidation--which was significantly lower in pretreated patients. A similar pattern of changes was found in the level of the lysosomal enzyme N-acetyl-glucosaminidase. Finally, pretreatment with vitamins E and C inhibited the decrease of catalase, observed in controls.
Language of Publication: English
Unique Identifier: 91230471

Return To Top
Return To Menu Position #10

MeSH Heading (Major): Ascorbic Acid|AD/*TU; Heart Surgery|*; Myocardial Reperfusion Injury|BL/*PC; Vitamin E|AD/*TU
MeSH Heading: Animal; Cardiopulmonary Bypass; Drug Therapy, Combination; Female; Hamsters; Human; Male; Middle Age; Phosphates|BL; Random Allocation; Uric Acid|BL

Publication Type: CLINICAL TRIAL; JOURNAL ARTICLE; RANDOMIZED CONTROLLED TRIAL
ISSN: 0006-9248
Country of Publication: CZECHOSLOVAKIA
CAS Registry/EC Number: 0 (Phosphates); 1406-18-4 (Vitamin E); 50-81-7 (Ascorbic Acid); 69-93-2 (Uric Acid)

Record 16 from database: MEDLINE
Return To Top
Return To Menu Position #10

Title: Gas phase oxidants of cigarette smoke induce lipid peroxidation and changes in lipoprotein properties in human blood plasma. Protective effects of ascorbic acid.
Author: Frei B; Forte TM; Ames BN; Cross CE
Address: Division of Biochemistry and Molecular Biology, University of California, Berkeley 94720.
Source: Biochem J, 1991 Jul 1, 277 ( Pt 1):, 133-8
Abstract: Cigarette smoke (CS) is known to contain a large number of oxidants. In order to assess the oxidative effects of CS on biological fluids, we exposed human blood plasma to filtered (gas phase) and unfiltered (whole) CS, and determined the rate of utilization of endogenous antioxidants in relation to the appearance of lipid hydroperoxides. Lipid peroxidation was measured with a specific and sensitive assay that can detect lipid hydroperoxides at plasma levels as low as 10 nM. We found that exposure of plasma to the gas phase of CS, but not to whole CS, induces lipid peroxidation once endogenous ascorbic acid has been oxidized completely. In addition, CS exposure caused oxidation of plasma protein thiols and albumin-bound bilirubin, whereas uric acid and alpha-tocopherol were not consumed at significant rates. In plasma exposed to the gas phase of CS, low-density lipoprotein exhibited slightly increased electrophoretic mobility, but there was no apparent degradation of apolipoprotein B. Our results support the concept of an increased vitamin C utilization in smokers, and suggest that lipid peroxidation induced by oxidants present in the gas phase of CS leads to potentially atherogenic changes in lipoproteins.
Language of Publication: English
Unique Identifier: 91307512

Return To Top
Return To Menu Position #10

MeSH Heading (Major): Ascorbic Acid|*PD; Lipid Peroxidation|*/DE; Lipoproteins|*BL/IP; Smoke|*AN; Smoking|*BL
MeSH Heading: Adult; Antioxidants; Electrophoresis, Polyacrylamide Gel; Human; Kinetics; Male; Middle Age; Support, U.S. Gov't, P.H.S.

Publication Type: JOURNAL ARTICLE
ISSN: 0264-6021
Country of Publication: ENGLAND
CAS Registry/EC Number: 0 (Antioxidants); 0 (Lipoproteins); 50-81-7 (Ascorbic Acid)

Record 17 from database: MEDLINE
Return To Top
Return To Menu Position #10

Title: Nonenzymatic degradation and salvage of dietary folate: physicochemical factors likely to influence bioavailability.
Author: Lucock MD; Priestnall M; Daskalakis I; Schorah CJ; Wild J; Levene MI
Address: Department of Clinical Medicine, University of Leeds, United Kingdom.
Source: Biochem Mol Med, 1995 Jun, 55:1, 43-53
Abstract: We investigated the oxidative degradation pathway of 5CH3-H4PteGlu, the main extracellular folate and the predominant form of the vitamin found in food and blood. 5CH3-H4PteGlu is oxidized to 5CH3-5,6-H2PteGlu which subsequently undergoes C9-N10 bond cleavage yielding a pteridine residue and P-ABG, the latter step resulting in irreversible loss of vitamin activity. Under moderately acid conditions typical of the postprandial gut (pH 3.5) 5CH3-H4PteGlu is fairly stable (t1/2 = 273.6 min), while 5CH3-5,6-H2PteGlu is rapidly degraded (t1/2 = 16.9 min). In a neutral environment (pH 6.4) stability is reversed; 5CH3-H4PteGlu t1/2 = 12.0 mins, 5CH3-5,6-H2PteGlu t1/2 = 1504.6 min. Ascorbic acid was efficacious in the facile salvage of 5CH3-H4PteGlu from 5CH3-5,6-H2PteGlu which occurred rapidly and with significant efficiency (100% conversion) under acid (pH 3.5) conditions, t1/2 = 1.3 min (1 mmol/liter ascorbate), but was less efficient under neutral (pH 6.4) conditions t1/2 = 273.6 min (36% conversion). The presence of zinc and iron broadly maintains the pattern of effect, but increases all reaction rates. PteGlu was stable under all conditions studied. These results obtained in an artificial environment were supported by findings in human gastric juice: at a gastric pH of 1.47 with low endogenous ascorbate (7.0 mumol/liter), 5CH3-5,6-H2PteGlu and 5CH3-H4PteGlu both degrade instantly via C9-N10 bond cleavage to yield an equimolar amount of P-ABG. If the same gastric juice is spiked at 58.0 mumol/liter ascorbate (moderate endogenous concentration), 5CH3-H4PteGlu is stable (t1/2 = 334.7 min), while 5CH3-5,6-H2PteGlu is instantly salvaged to 5CH3-H4PteGlu with 43.3% efficiency, and the remaining 5CH3-5,6-H2PteGlu is degraded to P-ABG. In gastric juice with an elevated pH of 7.0 and no endogenous ascorbate, 5CH3-5,6-H2PteGlu and 5CH3-H4PteGlu are both stable, with no C9-N10 bond cleavage. This, for 5CH3-H4PteGlu, is in apparent contrast to findings at pH 6.4 in an artificial environment. The same gastric juice spiked to 50 mumol/liter ascorbate did not result in 5CH3-H4PteGlu salvage from 5CH3-5,6-H2PteGlu.(ABSTRACT TRUNCATED AT 400 WORDS)
Language of Publication: English
Unique Identifier: 96028633

Return To Top
Return To Menu Position #10

MeSH Heading (Major): Tetrahydrofolates|CH/*ME/PK
MeSH Heading: Ascorbic Acid|ME/PD; Biological Availability; Chemistry, Physical; Diet; Folic Acid|AA/ME; Gastric Juice|ME; Human; Hydrogen-Ion Concentration; In Vitro; Kinetics; Oxidation-Reduction; Support, Non-U.S. Gov't

Publication Type: JOURNAL ARTICLE
ISSN: 1077-3150
Country of Publication: UNITED STATES

Record 18 from database: MEDLINE
Return To Top
Return To Menu Position #10

Title: Adherence, proliferation and collagen turnover by human fibroblasts seeded into different types of collagen sponges.
Author: Middelkoop E; de Vries HJ; Ruuls L; Everts V; Wildevuur CH; Westerhof W
Address: Department of Cell Biology and Histology, Academic Medical Center, Amsterdam, The Netherlands.
Source: Cell Tissue Res, 1995 May, 280:2, 447-53
Abstract: We describe an in vitro model that we have used to evaluate dermal substitutes and to obtain data on cell proliferation, the rate of degradation of the dermal equivalent, contractibility and de novo synthesis of collagen. We tested three classes of collagenous materials: (1) reconstituted non-crosslinked collagen, (2) reconstituted collagen that was chemically crosslinked with either glutaraldehyde, aluminium alginate or acetate, and (3) native collagen fibres, with or without other extracellular matrix molecules (elastin hydrolysate, hyaluronic acid or fibronectin). The non-crosslinked reconstituted collagen was degraded rapidly by human fibroblasts. The chemically crosslinked materials proved to be cytotoxic. Native collagen fibres were stable. In the absence of ascorbic acid, the addition of elastin hydrolysate to this type of matrix reduced the rate of collagen degradation. Both elastin hydrolysate and fibronectin partially prevented fibroblast-mediated contraction. Hyaluronic acid was only slightly effective in reducing the collagen degradation rate and more fibroblast-mediated contraction of the material was found than for the native collagen fibres with elastin hydrolysate and fibronectin. In the presence of ascorbate, collagen synthesis was enhanced in the native collagen matrix without additions and in the material containing elastin hydrolysate, but not in the material with hyaluronic acid. These results are indicative of the suitability of tissue substitutes for in vivo application.
Language of Publication: English
Unique Identifier: 95300193

Return To Top
Return To Menu Position #10

MeSH Heading (Major): Collagen|*/DE/ME; Fibroblasts|*CY/ME; Skin, Artificial|*; Surgical Sponges|*; Tissue Culture|*IS
MeSH Heading: Ascorbic Acid|PD; Cell Adhesion; Cell Division; Cells, Cultured; Cross-Linking Reagents|PD; Elastin|PD; Extracellular Matrix|ME; Fibronectins|PD; Human; Hyaluronic Acid|PD; Microscopy, Electron, Scanning; Support, Non-U.S. Gov't

Publication Type: JOURNAL ARTICLE
ISSN: 0302-766X
Country of Publication: GERMANY

Record 19 from database: MEDLINE
Return To Top
Return To Menu Position #10

Title: Induction of DNA fragmentation in human myelogenous leukemic cell lines by sodium 5,6-benzylidene-L-ascorbate and its related compounds.
Author: Kuribayashi N; Sakagami H; Sakagami T; Niimi E; Shiokawa D; Ikekita M; Takeda M; Tanuma S
Address: First Department of Biochemistry, School of Medicine, Showa University, Tokyo, Japan.
Source: Anticancer Res, 1994 May, 14:3A, 969-76
Abstract: High-performance liquid chromatography revealed that sodium 5,6-benzylidene-L-ascorbate (SBA), dissolved in distilled water, was gradually decomposed into ascorbic acid and benzaldehyde. Among these three compounds, ascorbic acid showed the most potent cytotoxic activity. The cytotoxic activity of each compound was significantly reduced during degradation in culture medium. Agarose gel electrophoresis and fluorometric determination of DNA revealed that ascorbic acid, as well as SBA, induced DNA fragmentation into nucleosomal oligomers in human myelogenous leukemic cell lines, but not in freshly isolated human peripheral blood cells. The results suggest that antitumor activity of SBA might be at least in part mediated by the action of ascorbic acid, a degradation product of SBA.
Language of Publication: English
Unique Identifier: 94354633

Return To Top
Return To Menu Position #10

MeSH Heading (Major): Antineoplastic Agents|*PD; Ascorbic Acid|*AA/ME/PD; Benzylidene Compounds|ME/*PD; DNA|*ME
MeSH Heading: Animal; Benzaldehydes|ME; Cell Line; Cell Survival|DE; Human; Leukemia, Myeloid|ME/PA; Mice; Support, Non-U.S. Gov't

Publication Type: JOURNAL ARTICLE
ISSN: 0250-7005
Country of Publication: GREECE

Record 20 from database: MEDLINE
Return To Top
Return To Menu Position #10
Return To Menu Position #20

Title: Stability of sodium 5,6-benzylidene-L-ascorbate.
Author: Sakagami H; Yamamura TS; Takahashi H; Shibuya I; Takeda M
Address: First Department of Biochemistry, School of Medicine, Showa University, Tokyo, Japan.
Source: Anticancer Res, 1995 Jul, 15:4, 1269-74
Abstract: The stability of sodium 5,6-benzylidene-L-ascorbate (SBA), consisting of two diastereomers, was investigated by high-performance liquid chromatography. In extensively acidic buffer, the acetal in SBA was immediately cleaved to liberate ascorbic acid and benzaldehyde. At higher pH, the cleavage of SBA was significantly reduced, but the degradation (due to possible opening of the lactone ring) of SBA was stimulated. The degradation rate of SBA was significantly increased with increasing temperature, and was higher than that of ascorbic acid or benzaldehyde. SBA was degraded with incubation time in culture medium, with accompanying loss of its biological activity, but only a marginal concentration of benzaldehyde, but not of ascorbic acid, was produced from SBA. The amount of SBA extracted from the apoptosing leukemic cells by 70% acetonitrile amounted to about 0.04% of that present in the medium fraction. These data suggest that SBA itself, but not contaminating ascorbic acid nor benzaldehyde, is responsible for the antitumor activity of SBA.
Language of Publication: English
Unique Identifier: 95382569

Return To Top
Return To Menu Position #10
Return To Menu Position #20

MeSH Heading (Major): Antineoplastic Agents|*CH; Ascorbic Acid|*AA/CH/PD; Benzylidene Compounds|*CH/PD
MeSH Heading: Chromatography, High Pressure Liquid; Drug Stability; Human; Hydrogen-Ion Concentration; Stereoisomerism; Support, Non-U.S. Gov't

Publication Type: JOURNAL ARTICLE
ISSN: 0250-7005
Country of Publication: GREECE

Record 21 from database: MEDLINE
Return To Top
Return To Menu Position #10
Return To Menu Position #20

Title: Inhibition of oxidative degradation of hyaluronic acid by uric acid.
Author: Liu KM; Swann D; Lee P; Lam KW
Address
Source: Curr Eye Res, 1984 Aug, 3:8, 1049-53
Abstract: It has been postulated that glycosaminoglycans in the trabeculum have an influence on aqueous humor drainage. Ascorbate reduces the viscosity of hyaluronic acid, and also increases outflow facility. Our recent observation of high urate concentrations in some glaucomatous eyes led us to study the influence of urate on oxidative degradation of hyaluronic acid by ascorbate. The viscosity of rooster comb hyaluronic acid was reduced slowly by ascorbate. Cupric sulfate accelerated ascorbate oxidation and also enhanced hyaluronic acid degradation. Urate inhibited ascorbate oxidation and prevented the copper catalyzed oxidative degradation of rooster comb hyaluronic acid. The range of urate concentrations used in this study was within the range of urate concentrations observed in glaucomatous eyes. The partially purified umbilical cord hyaluronic acid had lower viscosity than rooster comb hyaluronic acid, and rapidly degraded in the presence of ascorbate. The ascorbate effect on umbilical cord hyaluronic acid was partially prevented by urate.
Language of Publication: English
Unique Identifier: 85026249

Return To Top
Return To Menu Position #10
Return To Menu Position #20

MeSH Heading (Major): Aqueous Humor|*ME; Glaucoma|*ME; Hyaluronic Acid|AI/*ME/PD; Trabecular Meshwork|*ME; Uric Acid|*ME/PD
MeSH Heading: Animal; Ascorbic Acid|AI/PD; Chickens; Copper|PD; Drug Interactions; Female; Human; In Vitro; Male; Oxidation-Reduction|DE; Pregnancy; Support, Non-U.S. Gov't; Support, U.S. Gov't, P.H.S.; Umbilical Cord; Viscosity

Publication Type: JOURNAL ARTICLE
ISSN: 0271-3683
Country of Publication: ENGLAND

Record 22 from database: MEDLINE
Return To Top
Return To Menu Position #10
Return To Menu Position #20

Title: Ascorbate deficiency results in decreased collagen production: under-hydroxylation of proline leads to increased intracellular degradation.
Author: Berg RA; Steinmann B; Rennard SI; Crystal RG
Address
Source: Arch Biochem Biophys, 1983 Oct, 226:2, 681-6
Abstract: Collagen production by cultured human lung fibroblasts was examined when the cells were made deficient in ascorbate. Cells grown in the absence of ascorbate produced 30% less collagen during a 6-h labeling period than cells incubated with as little as 1 microgram/ml ascorbate during the labeling period. Cells grown without ascorbate produced under-hydroxylated collagen which was subject to increased intracellular degradation from a basal level of 16% to an enhanced level of 49% of all newly synthesized collagen. The likely mechanism for increased intracellular degradation is the inability of under-hydroxylated collagen to assume a triple-helical conformation causing it to be susceptible to intracellular degradation. Measurement of collagen production by enzyme linked immunoassay (ELISA) using antibodies directed against triple-helical determinants of collagen showed that both types I and III collagens were affected. In contrast, another connective tissue component, fibronectin, was not affected. Analysis by ELISA showed a greater decrease in collagen production than did analysis by the collagenase method, suggesting that some non-helical collagen chains (detected by collagenase but not by ELISA) were secreted in the absence of ascorbate. These results provide a mechanism to account, in part, for the deficiency of collagen in connective tissues which occurs in a state of ascorbate deficiency.
Language of Publication: English
Unique Identifier: 84051275

Return To Top
Return To Menu Position #20

MeSH Heading (Major): Ascorbic Acid Deficiency|*ME; Collagen|BI/*ME; Lung|*ME; Proline|*ME
MeSH Heading: Ascorbic Acid|PD; Cells, Cultured; Fibroblasts|DE/ME; Human; Hydroxyproline|ME; Kinetics; Support, Non-U.S. Gov't; Support, U.S. Gov't, P.H.S.

Publication Type: JOURNAL ARTICLE
ISSN: 0003-9861
Country of Publication: UNITED STATES

Record 23 from database: MEDLINE
Return To Top
Return To Menu Position #20

Title: A critical assessment of the effects of aminoguanidine and ascorbate on the oxidative modification of LDL: evidence for interference with some assays of lipoprotein oxidation by aminoguanidine.
Author: Scaccini C; Chiesa G; Jialal I
Address: Center for Human Nutrition, University of Texas, Southwestern Medical Center at Dallas 75235.
Source: J Lipid Res, 1994 Jun, 35:6, 1085-92
Abstract: Several lines of evidence support a role for oxidized low density lipoprotein (LDL) in the genesis of the atherosclerotic lesion. Hence, the effect of compounds with antioxidant properties on LDL oxidation assumes great significance. Ascorbate, a potent water-soluble chain-breaking antioxidant, has been shown to inhibit LDL oxidation. Aminoguanidine (AMG) is a pharmacological inhibitor of advanced non-enzymatic glycosylation. Recently it has been suggested that aminoguanidine might have an inhibitory effect on LDL oxidation, but total lipid peroxidation assayed by conjugated diene formation was not inhibited. Thus, in this study, we compared the effect of aminoguanidine with ascorbate to obtain a better appreciation of the effect of AMG on Cu(2+)-catalyzed LDL oxidation. Oxidative modification of LDL was monitored by assaying intermediates and end products of lipid peroxidation, conjugated dienes (CD), lipid peroxides (LPO), and relative electrophoretic mobility (REM). Apolipoprotein B-100 modification (increased fluorescence, fragmentation on SDS-PAGE, and 125I-labeled LDL degradation by human macrophages) was also measured. Ascorbate (100 microM) inhibited LDL oxidation by > 95%, as evidenced by all of the selected indices. Aminoguanidine (20 mM) substantially decreased thiobarbituric acid-reactive substances (TBARS) activity and lipid peroxide formation, but only partially prevented the increase of REM (-55%), apoB fluorescence (-39%), and degradation by macrophages (-54%). Unlike ascorbate, AMG failed to preserve alpha-tocopherol in LDL, prevent apoB-100 fragmentation, or inhibit conjugated diene formation during LDL oxidation. Furthermore, incubation of AMG with already oxidized LDL resulted in a significant decrease in TBARS activity and LPO, and 26.9% decrease in the REM of LDL.(ABSTRACT TRUNCATED AT 250 WORDS)
Language of Publication: English
Unique Identifier: 94358639

Return To Top
Return To Menu Position #20

MeSH Heading (Major): Ascorbic Acid|*PD; Guanidines|AD/*PD; Lipid Peroxidation|*DE; Lipoproteins, LDL|*ME
MeSH Heading: Apolipoproteins B|ME; Copper|ME; Dose-Response Relationship, Drug; Electrophoresis, Polyacrylamide Gel; Human; Kinetics; Macrophages|ME; Oxidation-Reduction; Support, Non-U.S. Gov't; Thiobarbituric Acid Reactive Substances|ME

Publication Type: JOURNAL ARTICLE
ISSN: 0022-2275
Country of Publication: UNITED STATES

Record 24 from database: MEDLINE
Return To Top
Return To Menu Position #20

Title: Bleaching of membrane-bound merocyanine 540 in conjunction with free radical-mediated lipid peroxidation.
Author: Pintar TJ; Lin F; Girotti AW
Address: Department of Biochemistry, Medical College of Wisconsin, Milwaukee 53226.
Source: Free Radic Biol Med, 1994 May, 16:5, 603-12
Abstract: The lipophilic dye merocyanine 540 (MC540) can photosensitize potentially lethal cell membrane damage as well as its own degradation (bleaching). Photobleaching in a test membrane, the human erythrocyte ghost has been examined. White light irradiation of MC540-sensitized ghosts resulted in lipid hydroperoxide (LOOH) formation, low-level thiobarbituric acid (TBA) reactivity, and dye bleaching (A568 decay). When the reaction was carried out in the presence of ascorbate (AH-), and added Fe3+, there was a large enhancement of TBA reactivity (indicative of free radical-mediated lipid peroxidation) and concomitant increase in the rate of photobleaching. Rapid bleaching also occurred when MC540 was incubated in the dark with ghosts that had been photoperoxidized with another dye (a phthalocyanine) and then exposed to AH-. The extent of bleaching in this system was found to be proportional to the starting level of LOOH. Like the wave of free radical lipid peroxidation that accompanied it, dye bleaching in AH(-)-treated, preperoxidized ghosts was stimulated by supplemental Fe3+, inhibited by desferrioxamine or butylated hydroxytoluene (BHT), but unaffected by catalase or superoxide dismutase. From this and related evidence, we deduce that: (1) in the absence of Fe3+/AH-, photoperoxidation and photobleaching occur independently and are nonradical, singlet oxygen-mediated processes; and (2) in the presence of Fe3+/AH-, 1-electron reduction of photogenerated LOOHs results in a surge of lipid peroxidation that amplifies dye loss via free radical processes. MC540 bleaching might be exploited as a relatively simple and sensitive indicator of lipid autoxidation in isolated membranes and cells.
Language of Publication: English
Unique Identifier: 94299217

Return To Top
Return To Menu Position #20

MeSH Heading (Major): Erythrocyte Membrane|DE/*ME; Lipid Peroxidation|*; Pyrimidinones|*ME/PD
MeSH Heading: Antioxidants; Ascorbic Acid|PD; Comparative Study; Ferric Compounds|PD; Free Radicals; Human; Photochemistry; Photosensitizing Agents|ME; Support, U.S. Gov't, P.H.S.; Thiobarbituric Acid Reactive Substances|ME

Publication Type: JOURNAL ARTICLE
ISSN: 0891-5849
Country of Publication: UNITED STATES

Record 25 from database: MEDLINE
Return To Top
Return To Menu Position #20

Title: Pentoxifylline. A hydroxyl radical scavenger.
Author: Freitas JP; Filipe PM
Address: ClÆinica DermatolÆogica UniversitÆaria, Faculdade de Medicina de Lisboa, Portugal.
Source: Biol Trace Elem Res, 1995 Jan, 47:1-3, 307-11
Abstract: Pentoxifylline (PTX), a tri-substituted purine and xanthine derivative, has been used for several years to improve microcirculation because of its hemorheological properties. PTX has also antifibrotic and anti-inflammatory effects. We studied the reaction of PTX with the hydroxyl radical and superoxide anion. Hydroxyl radical was generated by a mixture of ascorbic acid, H2O2 and Fe(III)-EDTA. We evaluated the iron-dependent degradation of deoxyribose, mediated by hydroxyl radical, in the presence of different concentrations of PTX (from 0.05 to 3 mM), measuring the degradation products of deoxyribose that react with 2-thiobarbituric acid (TBA). The reaction of PTX with hydroxyl radical occurred with a rate constant of (1.1 +/- 0.2) x 10(10) M-1/s. These results support the properties of PTX as a hydroxyl radical scavenger. Some authors verified that PTX decreases the release of superoxide anion from activated neutrophils. We studied the effect of PTX as a scavenger of superoxide generated in vitro by a hypoxanthine-xanthine oxidase system. PTX was not a superoxide anion scavenger in this system.
Language of Publication: English
Unique Identifier: 95298509

Return To Top
Return To Menu Position #20

MeSH Heading (Major): Free Radical Scavengers|*/PD; Hydroxyl Radical|*; Pentoxifylline|*/PD
MeSH Heading: Ascorbic Acid; Comparative Study; Edetic Acid; Ferric Compounds; Human; Hydrogen Peroxide; Iron Chelating Agents; Kinetics; Neutrophils|DE/PH; Superoxides; Xanthine Oxidase|ME; Xanthines|ME

Publication Type: JOURNAL ARTICLE
ISSN: 0163-4984
Country of Publication: UNITED STATES

Record 26 from database: MEDLINE
Return To Top
Return To Menu Position #20

Title: Ascorbic acid and urate in human seminal plasma: determination and interrelationships with chemiluminescence in washed semen.
Author: Thiele JJ; Friesleben HJ; Fuchs J; Ochsendorf FR
Address: Zentrum der Dermatologie und Venerologie, Abteilung II, Frankfurt/M, Germany.
Source: Hum Reprod, 1995 Jan, 10:1, 110-5
Abstract: Peroxidative damage induced by reactive oxygen species (ROS) has been proposed as one of the major causes of defective sperm function. The ROS detected in semen reflect an imbalance between ROS generation and degradation. The objective of the present study was to investigate the relationship between the oxidative and anti-oxidative potential in semen of infertile patients and healthy donors. Specimens were obtained from 28 patients and 18 healthy donors (controls). A conventional spermiogram, measurement of luminol-chemiluminescence (CL) in washed semen, and high performance liquid chromatography determination of ascorbic acid and urate concentrations in seminal plasma were performed. Oligozoospermic patients exhibited higher CL signals than controls (P < 0.001). Normozoospermic patients showed lower ascorbic acid (mean +/- SE: 491 +/- 46 microM, P < 0.04) and urate concentrations (320 +/- 22 microM, P < 0.009) than controls (612 +/- 35 and 426 +/- 26 microM respectively). Seminal plasma ascorbic acid was negatively correlated with the CL signals (P < 0.0006) and positively correlated with the percentage of spermatozoa with normal morphology (P < 0.006). This is the first report of a correlation between the anti-oxidant ascorbic acid in seminal plasma and ROS generation in human semen. Furthermore, the reduced ascorbic acid/urate concentrations found in semen of normozoospermic patients might be indicative of a reduced anti-oxidative protection.
Language of Publication: English
Unique Identifier: 95263752

Return To Top
Return To Menu Position #20

MeSH Heading (Major): Ascorbic Acid|*ME; Infertility, Male|*ME; Semen|*ME; Uric Acid|*ME
MeSH Heading: Adult; Antioxidants|ME; Chemiluminescence; Human; Male; Oligospermia|ME; Oxidation-Reduction; Reactive Oxygen Species|ME; Support, Non-U.S. Gov't

Publication Type: CLINICAL TRIAL; CONTROLLED CLINICAL TRIAL; JOURNAL ARTICLE
ISSN: 0268-1161
Country of Publication: ENGLAND

Record 27 from database: MEDLINE
Return To Top
Return To Menu Position #20

Title: Warfarin causes the degradation of protein C precursor in the endoplasmic reticulum.
Author: Tokunaga F; Wakabayashi S; Koide T
Address: Department of Life Science, Faculty of Science, Himeji Institute of Technology, Hyogo, Japan.
Source: Biochemistry, 1995 Jan, 34:4, 1163-70
Abstract: Warfarin, an antagonist of vitamin K, is known to disrupt the microsomal vitamin K cycle, which results in a decrease in the plasma level of protein C, an anticoagulant factor, as well as some other vitamin K-dependent coagulation factors. Here, we examined the effect of warfarin on the secretion of recombinant protein C expressed in human kidney 293 or BHK cells. In transient expression, warfarin caused a 2-4-fold decrease in the quantity of protein C secreted, compared to findings with vitamin K-treated cells. Pulse-chase experiments using stable cells showed that, although recombinant protein C was secreted in the presence of vitamin K, the decrease in the total amount of radioactivity in the warfarin-treated cells suggested intracellular degradation. This degradation depended on the concentration of warfarin and was not inhibited by an endoplasmic reticulum (ER)-Golgi transport inhibitor (brefeldin A) or by lysosomotropic inhibitors (chloroquine and NH4Cl). Thus, protein C synthesized in the presence of warfarin is probably selectively degraded, and this degradation occurs in a pre-Golgi, nonlysosomal compartment. Among the protease inhibitors tested, N-alpha-acetyl-Leu-Leu-methioninal and N-alpha-acetyl-Leu-Leu-norleucinal blocked the degradation of protein C precursor synthesized in the presence of warfarin, and the precursor accumulated intracellularly, in a dose-dependent manner. Both inhibitors, however, did not disturb the secretion of protein C precursor in the vitamin K-treated cells. Thus, a cysteine protease(s) appeared to be responsible for the degradation.(ABSTRACT TRUNCATED AT 250 WORDS)
Language of Publication: English
Unique Identifier: 95127687

Return To Top
Return To Menu Position #20

MeSH Heading (Major): Endoplasmic Reticulum|*EN; Protein C|*ME; Warfarin|*PD
MeSH Heading: Animal; Biological Transport|DE; Cell Compartmentation|DE; Cell Line; Enzyme Precursors|ME; Glucosaminidase|PD; Hamsters; Human; In Vitro; Protein Processing, Post-Translational|DE; Recombinant Proteins; Support, Non-U.S. Gov't; Vitamin K|PD

Publication Type: JOURNAL ARTICLE
ISSN: 0006-2960
Country of Publication: UNITED STATES

Record 28 from database: MEDLINE
Return To Top
Return To Menu Position #20

Title: Aggregation and precipitation of human relaxin induced by metal-catalyzed oxidation.
Author: Li S; Nguyen TH; Schöneich C; Borchardt RT
Address: Department of Pharmaceutical Chemistry, University of Kansas, Lawrence 66045, USA.
Source: Biochemistry, 1995 May, 34:17, 5762-72
Abstract: The interactions of proteins with reactive oxygen species may result in covalent modifications of amino acid residues in proteins and possible alterations of protein conformation. In an attempt to elucidate the mechanisms of the metal-catalyzed oxidation of human relaxin, we employed ascorbic acid/transition metal ion [Cu(II) or Fe(III)]/O2 as a model oxidizing system. Experimental results indicated selective oxidation of His and Met residues and rapid formation of aggregates (noncovalent, pH dependent) following the oxidation reaction. Amino acid analysis and LC/MS data following tryptic digestion demonstrated the oxidation of the His A(12) residue, which resulted in 2-oxohistidine and some other unidentified degradation products. The oxidation of both Met residues to Met-sulfoxides was also identified, and it was found that Met B(4) was more easily oxidized than Met B(25). The comparative kinetic studies of two Met-containing fragments of relaxin suggested that the preferred oxidation of Met B(4) is due to its close proximity to some metal-binding neighboring amino acid residues. These covalent alterations may lead to the modification of secondary and tertiary structure and increase the exposure of the hydrophobic surface of the protein which eventually induces aggregation of precipitation. The modification of relaxin by ascorbic acid/CuCl2 solution could be totally inhibited by the presence of EDTA. In contrast, catalase and superoxide dismutase showed no effects on the oxidation process.
Language of Publication: English
Unique Identifier: 95244506

Return To Top
Return To Menu Position #20

MeSH Heading (Major): Ascorbic Acid|*CH; Copper|*CH; Ferric Compounds|*CH; Relaxin|*CH
MeSH Heading: Amino Acid Sequence; Buffers; Chromatography, High Pressure Liquid; Electrophoresis, Polyacrylamide Gel; Histidine|CH; Human; Hydrogen-Ion Concentration; Macromolecular Systems; Methionine|CH; Molecular Sequence Data; Oxidation-Reduction; Peptide Fragments|CH; Precipitation; Protein Structure, Secondary; Protein Structure, Tertiary; Support, Non-U.S. Gov't; Trypsin|ME

Publication Type: JOURNAL ARTICLE
ISSN: 0006-2960
Country of Publication: UNITED STATES

Record 29 from database: MEDLINE
Return To Top
Return To Menu Position #20

Title: The role of superoxide and hydroxyl radicals in the degradation of hyaluronic acid induced by metal ions and by ascorbic acid.
Author: Wong SF; Halliwell B; Richmond R; Skowroneck WR
Address
Source: J Inorg Biochem, 1981 Apr, 14:2, 127-34
Abstract: Purified commercial hyaluronic acid contains significant amounts of iron. Addition of Fe2+ to solutions of it causes depolymerization, which is inhibited by catalase and scavengers of the hydroxyl radical (. OH) but not by superoxide dismutase. Fe3+ is ineffective. Ascorbic acid also depolymerizes hyaluronic acid, apparently because it can reduce Fe3+ in the reaction mixtures to Fe2+. Ascorbate-induced depolymerization is inhibited by the specific iron chelator desferrioxamine, by catalase, and by scavengers of the hydroxyl radical. The relevance of these observations to rheumatoid arthritis and inflammatory joint diseases is discussed.
Language of Publication: English
Unique Identifier: 81241541

Return To Top
Return To Menu Position #20

MeSH Heading (Major): Ascorbic Acid|*/ME; Hyaluronic Acid|*/ME; Iron|*/ME
MeSH Heading: Arthritis, Rheumatoid|ME; Chemistry; Free Radicals; Human; Superoxides|ME; Support, Non-U.S. Gov't; Synovial Fluid|ME

Publication Type: JOURNAL ARTICLE
ISSN: 0162-0134
Country of Publication: UNITED STATES

Record 30 from database: MEDLINE
Return To Top
Return To Menu Position #20
Return To Menu Position #30

Title: Collagen degradation in human lung fibroblasts: extent of degradation, role of lysosomal proteases, and evaluation of an alternate hypothesis.
Author: Bienkowski RS
Address
Source: J Cell Physiol, 1984 Oct, 121:1, 152-8
Abstract: Experiments were conducted to determine the extent and variability of collagen degradation in human fetal lung fibroblasts. Cells were incubated with [14C]proline, and degradation was measured by determining the hydroxy[14C]proline in a low molecular weight fraction relative to total hydroxy[14C]proline. Average (basal) degradation in stationary phase HFL-1 cells incubated for 8 h was 16 +/- 3%, and substantial alterations in the composition of the labeling medium, e.g., omitting serum and varying pH between 6.8 and 7.8, had no effect. Organic buffers slightly lowered degradation in a manner that was independent of pH. Collagen degradation in two other lung cell lines, Wl-38 and lMR-90, did not differ from the level in HFL-1. Degradation was significantly higher (23 +/- 5%) in HFL-1 cultures labeled for 24 h rather than 8 h, and pulse-washout experiments showed that the rate of degradation was not uniform: after an 8-h pulse, 11% of the hydroxy [14C]proline in the medium was in the low molecular weight fraction, but 31% was in this fraction after a 16-h washout. The lack of effect of either serum deprivation or elevated pH suggests that lysosomal proteases have no direct role in basal degradation; however, NH4Cl decreased the enhanced degradation observed in ascorbate deficiency to basal level, indicating that abnormal molecules synthesized under those conditions are degraded by lysosomal proteases. The appearance of small hydroxy[14C]proline-containing molecules was inhibited by alpha alpha'dipyridyl and cycloheximide in a dose-dependent and reversible manner, demonstrating that their production depends on enzymatic hydroxylation of proline and protein synthesis.
Language of Publication: English
Unique Identifier: 85007143

Return To Top
Return To Menu Position #20
Return To Menu Position #30

MeSH Heading (Major): Collagen|*ME; Lung|*ME; Lysosomes|*ME
MeSH Heading: Ammonium Chloride|PD; Ascorbic Acid Deficiency|ME; Cells, Cultured; Cycloheximide|PD; Human; Kinetics; Peptide Hydrolases|ME; Support, Non-U.S. Gov't; Support, U.S. Gov't, P.H.S.; 2,2'-Dipyridyl|PD

Publication Type: JOURNAL ARTICLE
ISSN: 0021-9541
Country of Publication: UNITED STATES

Record 31 from database: MEDLINE
Return To Top
Return To Menu Position #20
Return To Menu Position #30

Title: Biochemical, microbiological, and nutritional aspects of kimchi (Korean fermented vegetable products).
Author: Cheigh HS; Park KY
Address: Department of Food Science and Nutrition, Pusan National University, Korea.
Source: Crit Rev Food Sci Nutr, 1994, 34:2, 175-203
Abstract: Kimchi is a traditional, fermented Korean food that is prepared through a series of processes, including pretreatment of oriental cabbage (or radish), brining, blending with various spices and other ingredients, and fermentation. The characteristics of kimchi differ depending on the kimchi varieties, raw materials used, process, fermentation, and preservation methods. However, kimchi has typical biochemical, nutritional, and organoleptic properties and health-related functions. Kimchi fermentation is initiated by various microorganisms originally present in the raw materials, but the fermentation is gradually dominated by lactic acid bacteria. Numerous physicochemical and biological factors influence the fermentation, growth, and sequential appearance of principal microorganisms involved in the fermentation. Complex biochemical changes occur depending on the environmental conditions before, during, and after fermentation. The most important characteristics are the compositional changes of sugars and vitamins (especially ascorbic acid), formation and accumulation of organic acids, and texture degradation and softening. Nutritionally, kimchi is an important source of vitamins, minerals, dietary fiber, and other nutrients. This review covers in some detail the biochemical, microbiological, and nutritional characteristics of kimchi.
Language of Publication: English
Unique Identifier: 94280596

Return To Top
Return To Menu Position #20
Return To Menu Position #30

MeSH Heading (Major): Food Handling|*MT; Vegetables|*/CL/ME/MI
MeSH Heading: Amino Acids|AN; Ascorbic Acid|ME; Fermentation; Food Microbiology; Food Preservation; Human; Korea; Nutritive Value; Taste; Vitamins|ME

Publication Type: JOURNAL ARTICLE; REVIEW; REVIEW, ACADEMIC
ISSN: 1040-8398
Country of Publication: UNITED STATES

Record 32 from database: MEDLINE
Return To Top
Return To Menu Position #20
Return To Menu Position #30

Title: Retinoic acid-induced inhibition of type I collagen gene expression by human lung fibroblasts.
Author: Krupsky M; Fine A; Berk JL; Goldstein RH
Address: Pulmonary Center, Boston University School of Medicine, MA.
Source: Biochim Biophys Acta, 1994 Oct, 1219:2, 335-41
Abstract: We examined alpha 1(I) collagen gene expression in all-trans retinoic acid (RA)-treated human lung fibroblast cultures. RA (10(-5)M) decreased steady-state levels for alpha 1(I) collagen mRNA by at least 75% after 24 h. The inhibition was evident within 8 h after addition of RA, was dose dependent and reversible. Treatment with 9-cis-retinoic acid did not affect alpha 1(I) collagen mRNA levels. RA also inhibited the increases in alpha 1(I) mRNA stimulated by transforming growth factor-beta (TGF-beta). The RA-mediated decrease in alpha 1(I) collagen mRNA was blocked by cycloheximide treatment, suggesting that synthesis of a protein intermediate is required for the inhibition. The RA-induced decrease in alpha 1(I) collagen mRNA levels was not mediated by increases in prostaglandin E2 production. RA decreased alpha 1(I) gene transcription as determined by nuclear run-off assays but did not significantly alter the rate of degradation of the alpha 1(I) transcript as determined by actinomycin D treatment. Studies employing cells stably transfected with constructs containing portions of the alpha 1(I) collagen promoter indicate that the DNA sequences which mediate the inhibitory effect are located within 900 bases from the transcription start site.
Language of Publication: English
Unique Identifier: 95002146

Return To Top
Return To Menu Position #20
Return To Menu Position #30

MeSH Heading (Major): Collagen|*GE; Lung|*ME; Tretinoin|*PD
MeSH Heading: Ascorbic Acid|PD; Cycloheximide|PD; Fibroblasts; Human; In Vitro; Promoter Regions (Genetics); RNA, Messenger|GE; Support, Non-U.S. Gov't; Support, U.S. Gov't, Non-P.H.S.; Support, U.S. Gov't, P.H.S.; Transcription, Genetic|DE

Publication Type: JOURNAL ARTICLE
ISSN: 0006-3002
Country of Publication: NETHERLANDS

Record 33 from database: MEDLINE
Return To Top
Return To Menu Position #20
Return To Menu Position #30

Title: Iodine-mediated inactivation of lipid- and nonlipid-enveloped viruses in human antithrombin III concentrate.
Author: Highsmith F; Xue H; Chen X; Benade L; Owens J; Shanbrom E; Drohan W
Address: Holland Laboratory, Plasma Derivatives Department, American Red Cross, Rockville, MD 20855, USA.
Source: Blood, 1995 Jul, 86:2, 791-6
Abstract: Human plasma-derived protein concentrates intended for clinical use must be treated for viral inactivation to ensure patient safety. This study explored the use of liquid iodine for inactivation of several lipid- and nonlipid-enveloped viruses in an antithrombin III (AT-III) concentrate. Iodine at levels of 0.01% to 0.02% caused between 43% and 94% loss of AT-III activity, as well as degradation of AT-III as shown by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blot analysis. However, addition of up to 0.1% human albumin protected the AT-III against both inactivation and fragmentation. At albumin levels sufficient to retain greater than 75% of AT-III activity, greater than 6 logs of sindbis, encephalomyocarditis, and vesicular stomatitis viruses, greater than 4 logs of pseudorabies, and greater than 3 logs of human immunodeficiency virus were inactivated. Except with sindbis virus, this represented complete inactivation of all the viruses spiked into the AT-III concentrate.
Language of Publication: English
Unique Identifier: 95329739

Return To Top
Return To Menu Position #20
Return To Menu Position #30

MeSH Heading (Major): Antithrombin III|*IP; Antiviral Agents|*PD; Blood|*VI; Iodine|*PD; Viruses|*DE/IP/UL
MeSH Heading: Animal; Ascorbic Acid|PD; Cercopithecus aethiops; Encephalomyocarditis Virus|DE/IP; Herpesvirus 1, Suid|DE/IP; Human; HIV-1|DE/IP; Safety; Serum Albumin|PD; Sindbis Virus|DE/IP; Vero Cells; Vesicular Stomatitis-Indiana Virus|DE/IP

Publication Type: JOURNAL ARTICLE
ISSN: 0006-4971
Country of Publication: UNITED STATES

Record 34 from database: MEDLINE
Return To Top
Return To Menu Position #20
Return To Menu Position #30

Title: The effect of synovial fluid proteins in the degradation of hyaluronic acid induced by ascorbic acid.
Author: Motohashi N; Mori I
Address
Source: J Inorg Biochem, 1985 May, 24:1, 69-74
Abstract: The degradation of hyaluronic acid induced by ascorbic acid and the effect of synovial fluid proteins, such as ceruloplasmin, transferrin, and albumin, were investigated on the basis of the elution volume and the molecular weight of hyaluronic acid using high-performance gel permeation chromatography. Hyaluronic acid was degraded to less than one-third of the original molecular weight in the range of the physiological concentrations of ascorbic acid. Synovial fluid proteins protected against the ascorbate-dependent degradation of hyaluronic acid at their physiological concentrations. It is suggested that the inhibitory activity of ceruloplasmin mainly depends on the ferroxidase activity and that of transferrin is probably due to iron binding property.
Language of Publication: English
Unique Identifier: 85236299

Return To Top
Return To Menu Position #30

MeSH Heading (Major): Ascorbic Acid|ME/*PD; Hyaluronic Acid|*ME; Proteins|ME/*PD; Synovial Fluid|*ME
MeSH Heading: Albumins|PD; Binding Sites; Ceruloplasmin|PD; Human; In Vitro; Iron|ME; Molecular Weight; Transferrin|PD

Publication Type: JOURNAL ARTICLE
ISSN: 0162-0134
Country of Publication: UNITED STATES

Record 35 from database: MEDLINE
Return To Top
Return To Menu Position #30

Title: Modulation by sodium ascorbate of the effect of chloroquine on low density lipoprotein retention and degradation in cultured human skin fibroblasts.
Author: Coetzee GA; Stein O; Stein Y
Address
Source: Atherosclerosis, 1979 Mar, 32:3, 277-87
Abstract: Human skin fibroblasts in culture were incubated for 48 h with 125I-labelled low density lipoprotein and chloroquine in the presence and absence of sodium ascorbate. Pretreatment of the cells for 3 days with sodium ascorbate and addition of the vitamin during incubation resulted in a decrease in cellular retention and an increase in degradation of the labelled low density lipoprotein. Similar results were obtained when the cells were pretreated for 3 days but the vitamin was not added during the final 48 h of incubation. Pretreatment of the cells with dithiothreitol, butylated hydroxy-toluene, beta-mercaptoethanol and D-alpha-tocopherol had a similar effect to that of ascorbate, i.e. reduction in low density lipoprotein retention and increase in degradation. Neither ascorbate nor the other reducing agents affected low density lipoprotein catabolism in control cells not treated with chloroquine. Sodium ascorbate pretreatment resulted also in a slight but significant alleviation of the chloroquine-induced inhibition of hydrolysis of cholesterol linoleate. It is proposed that sodium ascorbate by virtue of its reducing properties provides some protection to the intralysosomal hydrolases against the inhibitory action of chloroquine. If cholesterol accumulation in human and experimental atheroma is caused by partial inhibition of lysosomal enzymes, sodium ascorbate could play a role in the alleviation of such an inhibition.
Language of Publication: English
Unique Identifier: 79231697

Return To Top
Return To Menu Position #30

MeSH Heading (Major): Ascorbic Acid|*PD; Chloroquine|*PD; Fibroblasts|DE/*EN; Lipoproteins, LDL|*ME
MeSH Heading: Adult; Cells, Cultured; Cholesterol Esters|ME; Human; Hydrolases|ME; Lysosomes|EN; Male

Publication Type: JOURNAL ARTICLE
ISSN: 0021-9150
Country of Publication: NETHERLANDS

Record 36 from database: MEDLINE
Return To Top
Return To Menu Position #30

Title: Measurement of ascorbate and dehydroascorbate contents in biological fluids.
Author: Koshiishi I; Imanari T
Address: Faculty of Pharmaceutical Sciences, Chiba University, Japan.
Source: Anal Chem, 1997 Jan, 69:2, 216-20
Abstract: Instabilities of ascorbate and dehydroascorbate throughout sample processing are clearly a significant aspect of quantifying of them. Contents of ascorbate in biological fluids decrease with measurable oxidation occurring within minutes to hours. Similarly, dehydroascorbate disappears with chemical or enzymatic degradation within minutes. The half-life of dehydroascorbate in human heparinized plasma was approximately 2 min. These results indicated that the amount of dehydroascorbate present in sample solutions is a function of both the oxidation of ascorbate and the degradation of dehydroascorbate during the processing of biological fluids. To quantify ascorbate and dehydroascorbate concentrations in biological fluids including circulating blood plasma and urine, we established a high-performance liquid chromatographic method, which requires no pretreatment of sample solutions.
Language of Publication: English
Unique Identifier: 97151962

Return To Top
Return To Menu Position #30

MeSH Heading (Major): Ascorbic Acid|*AN/BL/UR; Dehydroascorbic Acid|*AN/BL/UR
MeSH Heading: Chromatography, High Pressure Liquid; Human

Publication Type: JOURNAL ARTICLE
ISSN: 0003-2700
Country of Publication: UNITED STATES

Record 37 from database: MEDLINE
Return To Top
Return To Menu Position #30

Title: Ascorbic acid stimulates collagen production without altering intracellular degradation in cultured human skin fibroblasts.
Author: Geesin J; Murad S; Pinnell SR
Address
Source: Biochim Biophys Acta, 1986 Apr, 886:2, 272-4
Abstract: The influence of ascorbic acid on intracellular degradation of collagen synthesized by cultured human-skin fibroblasts was examined. In confluent cells maintained in 0.5% serum-supplemented medium, ascorbic acid had no significant effect on collagen degradation measured with hydroxyproline as the marker. Similar results were obtained when collagen degradation was measured with the marker hydroxylysine, the cellular synthesis of which is independent of ascorbic acid. The stimulatory effects of ascorbic acid on collagen production therefore cannot be explained by a change in the rate of degradation. Ascorbic acid acts at some as yet undetermined level to increase the rate of collagen synthesis.
Language of Publication: English
Unique Identifier: 86187933

Return To Top
Return To Menu Position #30

MeSH Heading (Major): Ascorbic Acid|*PD; Collagen|*BI
MeSH Heading: Cells, Cultured; Fibroblasts|ME; Human; Hydroxylysine|ME; Hydroxyproline|ME; Infant, Newborn; Male; Skin|ME; Support, Non-U.S. Gov't; Support, U.S. Gov't, P.H.S.

Publication Type: JOURNAL ARTICLE
ISSN: 0006-3002
Country of Publication: NETHERLANDS

Record 38 from database: MEDLINE
Return To Top
Return To Menu Position #30

Title: Lipid peroxidation and haemoglobin degradation in red blood cells exposed to t-butyl hydroperoxide. Effects of the hexose monophosphate shunt as mediated by glutathione and ascorbate.
Author: Trotta RJ; Sullivan SG; Stern A
Address
Source: Biochem J, 1982 May, 204:2, 405-15
Abstract: Lipid peroxidation and haemoglobin degradation were the two extremes of a spectrum of oxidative damage in red cells exposed to t-butyl hydroperoxide. The exact position in this spectrum depended on the availability of glucose and the ligand state of haemoglobin. In red cells containing oxy- or carbonmono-oxy-haemoglobin, hexose monophosphate-shunt activity was mainly responsible for metabolism of t-butyl hydroperoxide; haem groups were the main scavengers in red cells containing methaemoglobin. Glutathione, via glutathione peroxidase, accounted for nearly all of the hydroperoxide metabolizing activity of the hexose monophosphate shunt. Glucose protection against lipid peroxidation was almost entirely mediated by glutathione, whereas glucose protection of haemoglobin was only partly mediated by glutathione. Physiological concentrations of intracellular or extracellular ascorbate had no effect on consumption of t-butyl hydroperoxide or oxidation of haemoglobin. Ascorbate was mainly involved in scavenging chain-propagating species involved in lipid peroxidation. The protective effect of intracellular ascorbate against lipid peroxidation was about 100% glucose-dependent and about 50% glutathione-dependent. Extracellular ascorbate functioned largely without a requirement for glucose metabolism, although some synergistic effects between extracellular ascorbate and glutathione were observed. Lipid peroxidation was not dependent on the rate or completion of t-butyl hydroperoxide consumption but rather on the route of consumption. Lipid peroxidation appears to depend on the balance between the presence of initiators of lipid peroxidation (oxyhaemoglobin and low concentrations of methaemoglobin) and terminators of lipid peroxidation (glutathione, ascorbate, high concentrations of methaemoglobin).
Language of Publication: English
Unique Identifier: 82283977

Return To Top
Return To Menu Position #30

MeSH Heading (Major): Erythrocytes|DE/*ME; Hemoglobins|*ME; Hexosephosphates|*ME; Lipids|*BL
MeSH Heading: Ascorbic Acid|BL; Carboxyhemoglobin|ME; Ethylmaleimide|PD; Glutathione|BL; Human; In Vitro; Methemoglobin|ME; Oxidation-Reduction; Oxyhemoglobins|ME; Peroxides; Support, U.S. Gov't, P.H.S.

Publication Type: JOURNAL ARTICLE
ISSN: 0006-2936
Country of Publication: ENGLAND

Record 39 from database: MEDLINE
Return To Top
Return To Menu Position #30

Title: Stability of rifampin in plasma: consequences for therapeutic monitoring and pharmacokinetic studies.
Author: Le Guellec C; Gaudet ML; Lamanetre S; Breteau M
Address: Laboratoire de Pharmacologie et Toxicologie Cliniques, CHU Bretonneau, Tours, France.
Source: Ther Drug Monit, 1997 Dec, 19:6, 669-74
Abstract: Interest in determining plasma levels of rifampin for adjustment of dosage regimens has increased, but conflicting results exist concerning rifampin stability. The authors developed a high-performance liquid chromatography assay to monitor rifampin plasma concentrations that was used to study the possible degradation of rifampin in plasma samples. This report describes the stability of rifampin in plasma kept at an ambient temperature for 24 hours or stored at -20 degrees C for 2 weeks. The possible protective effect of adding ascorbic acid was also studied. The results indicate that rifampin degrades rapidly in plasma at an ambient temperature, and a 54% loss was observed within 8 hours. This degradation can be effectively prevented by adding ascorbic acid, thus prolonging stability for up to 12 hours. The same results were observed with samples obtained as part of routine drug monitoring. Degradation was found to be greater at low rifampin concentrations. The authors subsequently demonstrated that decomposition of rifampin occurs after storage for 1 week at -20 degrees C. However, in samples supplemented with ascorbic acid before freezing, no degradation was observed within 14 days at the two concentrations tested. Rifampin was more stable in specimens drawn from treated patients, suggesting possible in vivo stabilization of the molecule. Further studies are needed to determine stability of rifampin for longer storage periods. On the basis of these results, plasma samples obtained from patients receiving rifampin should be immediately supplemented with ascorbic acid and analyzed as soon as possible.
Language of Publication: English
Unique Identifier: 98081462

Return To Top
Return To Menu Position #30

MeSH Heading (Major): Antibiotics, Antitubercular|*BL/CH/PK; Rifampin|*BL/CH/PK
MeSH Heading: Ascorbic Acid|PD; Chromatography, High Pressure Liquid; Double-Blind Method; Drug Monitoring|MT; Drug Stability; Human; Temperature

Publication Type: CLINICAL TRIAL; JOURNAL ARTICLE; RANDOMIZED CONTROLLED TRIAL
ISSN: 0163-4356
Country of Publication: UNITED STATES

Record 40 from database: MEDLINE
Return To Top
Return To Menu Position #30

Title: High galactose levels in vitro and in vivo impair ascorbate regeneration and increase ascorbate-mediated glycation in cultured rat lens.
Author: Saxena P; Saxena AK; Monnier VM
Address: Institute of Pathology, Case Western Reserve University, Cleveland, OH 44106, USA.
Source: Exp Eye Res, 1996 Nov, 63:5, 535-45
Abstract: In contrast to conventional view that glucose is the sole glycating agent, ascorbate has now emerged as a potential precursor of advanced glycation products in lenses during cataractogenesis, owing to the high concentration present in human lens. The effects of high hexose environment in vitro and in vivo on the disruption of redox equilibrium of ascorbate (ASA) to dehydroascorbate (DHA), which is required for ascorbate-mediated crystallin modification by the Maillard reaction during cataractogenesis were examined. Organ culture experiments were performed with rat lenses that were first exposed to high galactose levels in vitro and in vivo and then incubated with 1-14C-labeled ASA, DHA or DKG (2,3-diketogulonic acid). Formation of ASA degradation products as a function of time was assessed by radiometric TLC method. Upon incubation with ASA or DHA, an elevated level of the degradation product, DKG, was detected in lenses exposed to galactose in vivo and in vitro. ASA uptake was significantly enhanced in the galactosemic lenses as compared to controls (P = 0.01). Regeneration of ASA from DHA in both galactose treated and galactosemic lenses was impaired when compared to control lens which completely converted DHA from the medium into ASA. Surprisingly, the galactose exposed lenses showed enhanced permeability to DKG which was picked up readily from the medium in contrast to normal healthy lenses which remained impermeable to DKG. Galactose exposed lenses both in vitro and in vivo showed a 5-9-fold increase in crystallin bound Schiff base-linked radioactivity when incubated with 1-14C-labeled ASA or DHA. As a preamble to the question of whether lens pigmentation predisposes towards ascorbate oxidation, lens homogenate from normal young and old pigmented cataractous lenses were incubated with [1-14C]ASA. After 2 days, ASA levels were found to have decreased by 74% and DKG levels increased by 48% in brunescent lens as compared to the young lens. These data demonstrated that profound abnormalities in ASA metabolism exist in lenses exposed to a high sugar environment suggestive of a breakdown of the redox equilibrium of ASA to DHA and a loss of membrane permeability barrier for DKG. The latter would further contribute toward a ASA-catalysed Maillard reaction in the redox impaired lens.
Language of Publication: English
Unique Identifier: 97147585

Return To Top
Return To Menu Position #30

MeSH Heading (Major): Ascorbic Acid|*ME/PH; Cataract|CI/*ME; Galactose|*PD; Lens, Crystalline|*DE/*ME
MeSH Heading: Animal; Crystallins|ME; Dehydroascorbic Acid|ME; Human; In Vitro; Male; Organ Culture; Oxidation-Reduction|DE; Rats; Rats, Sprague-Dawley; Support, Non-U.S. Gov't; Support, U.S. Gov't, P.H.S.; Time Factors; 2,3-Diketogulonic Acid|ME

Publication Type: JOURNAL ARTICLE
ISSN: 0014-4835
Country of Publication: ENGLAND

Record 41 from database: MEDLINE
Return To Top
Return To Menu Position #30
Return To Menu Position #40

Title: Lack of effect of ascorbic acid, hippuric acid, and methenamine (urinary formaldehyde) on the copper-reduction glucose test in geriatric patients.
Author: Nahata MC; McLeod DC
Address
Source: J Am Geriatr Soc, 1980 May, 28:5, 230-3
Abstract: Ascorbic acid and hippuric acid (from cranberry juice) are commonly used to acidify the urine for the purpose of enhancing the degradation of therapeutic methenamine mandelate to urinary formaldehyde. A study was made of 27 nondiabetic geriatric patients with indwelling Foley catheters and chronic bacteriuria who were treated with methenamine mandelate (4 gm), ascorbic acid (4 gm), and cranberry cocktail (1 liter) daily. All of 972 urine samples showed formaldehyde in mean concentrations between 14 and 25 microgram/ml. No glucose was found when the urine was tested by the copper-reduction method. In vitro false positive reactions reported in the literature do not appear to be duplicated as an in vivo problem.
Language of Publication: English
Unique Identifier: 80160940

Return To Top
Return To Menu Position #30
Return To Menu Position #40

MeSH Heading (Major): Ascorbic Acid|*TU; Copper|*ME; Glucose Tolerance Test|*MT; Hippurates|*TU; Methenamine|*TU
MeSH Heading: Aged; Bacteriuria|DT/UR; Case Report; False Positive Reactions; Female; Formaldehyde|UR; Glycosuria|UR; Human; Male

Publication Type: JOURNAL ARTICLE
ISSN: 0002-8614
Country of Publication: UNITED STATES

Record 42 from database: MEDLINE
Return To Top
Return To Menu Position #40

Title: Differing effects of probucol and vitamin E on the oxidation of lipoproteins, ceroid accumulation and protein uptake by macrophages.
Author: Hunt JV; Bottoms MA; Taylor SE; Lyell V; Mitchinson MJ
Address: Department of Pathology, University of Cambridge, UK.
Source: Free Radic Res, 1994 Mar, 20:3, 189-201
Abstract: Studies using 125I-low density lipoprotein (125I-LDL) show that probucol (10 microM) and alpha-tocopherol (100 microM) inhibit protein degradation in LDL exposed to Cu (II) in vitro. The inhibitory effect of alpha-tocopherol on protein fragmentation exceeded that of probucol. On the other hand, probucol was more able to inhibit lipid peroxidation. The subsequent uptake of Cu (II)-oxidised 125I-LDL by murine peritoneal macrophages (MPM) was virtually unaffected by the presence of probucol during LDL oxidation. The same was not true for alpha-tocopherol which led to lower levels of 125I-LDL uptake by MPM. Thus, it appears that although the antioxidant activity of probucol exceeds that of alpha-tocopherol for lipid oxidation, the reverse is true for protein degradation and, perhaps more significantly, for subsequent macrophage uptake. Further studies used artificial lipoproteins composed of cholesteryl linoleate or cholesteryl arachidonate complexed with bovine serum albumin. Culture of these artificial lipoproteins with MPM resulted in protein uptake, protein degradation, cholesterol oxidation to cholest-5-en-3 beta,7 beta-diol and the intracellular accumulation of ceroid in MPM. The presence of alpha-tocopherol (0-100 microM) inhibited all of these processes. Probucol (0-10 microM) inhibited ceroid accumulation and cholesterol oxidation to the same degree as alpha-tocopherol (0-100 microM) but had no effect upon protein degradation and protein uptake. Control studies of lipoproteins incubated without cells showed that protein degradation by cell-independent processes was also inhibited by alpha-tocopherol, but not by probucol. These observations are discussed in the context of the role of lipoprotein oxidation in atherogenesis.
Language of Publication: English
Unique Identifier: 94290598

Return To Top
Return To Menu Position #40

MeSH Heading (Major): Ceroid|*ME; Lipid Peroxidation|*DE; Lipoproteins|*ME; Macrophages, Peritoneal|DE/*ME; Probucol|*PD; Serum Albumin, Bovine|*ME; Vitamin E|*ME
MeSH Heading: Animal; Biological Transport|DE; Cells, Cultured; Comparative Study; Dose-Response Relationship, Drug; Human; Kinetics; Lipoproteins, LDL|BL/IP/ME; Male; Mice; Mice, Inbred BALB C; Oxidation-Reduction; Support, Non-U.S. Gov't

Publication Type: JOURNAL ARTICLE
ISSN: 1071-5762
Country of Publication: SWITZERLAND

Record 43 from database: MEDLINE
Return To Top
Return To Menu Position #40

Title: Induction of collagen synthesis by ascorbic acid. A possible mechanism.
Author: Pinnel SR; Murad S; Darr D
Address: Department of Medicine, Duke University Medical Center, Durham, NC.
Source: Arch Dermatol, 1987 Dec, 123:12, 1684-6
Abstract: L-Ascorbic acid stimulates procollagen synthesis in cultured human skin fibroblasts without appreciably altering noncollagen protein synthesis. The effect is unrelated to intracellular degradation of newly synthesized procollagen. Levels of mRNA for pro alpha 1(I), pro alpha 2(I), and pro alpha 1(III), measured by hybridization with the corresponding cDNA probes, are elevated in the presence of ascorbic acid, whereas the level of mRNA for fibronectin is unchanged. Levels of functional mRNA for procollagen, measured in a cell-free translation assay, are specifically increased in the presence of ascorbic acid. Thus, ascorbic acid appears to control the expression of three different procollagen genes, each of which is located on a separate chromosome. It is proposed that intracellularly accumulated procollagen in ascorbate deficiency may lead to a translational repression of procollagen synthesis. Ascorbic acid may relieve this block by promoting hydroxyproline formation and, consequently, secretion of procollagen from the cell. The increased level of procollagen mRNA under the influence of ascorbic acid may be secondary to increased synthesis of procollagen polypeptides; the control point may be gene transcription or mRNA degradation.
Language of Publication: English
Unique Identifier: 88076018

Return To Top
Return To Menu Position #40

MeSH Heading (Major): Ascorbic Acid|AA/*PD; Collagen|*BI
MeSH Heading: Aging|DE/ME; Cells, Cultured; Human; Procollagen|ME; Procollagen-Lysine, 2-Oxoglutarate 5-Dioxygenase|ME; Procollagen-Proline Dioxygenase|ME; RNA, Messenger|ME; Skin|DE/ME; Support, Non-U.S. Gov't; Support, U.S. Gov't, P.H.S.

Publication Type: JOURNAL ARTICLE; REVIEW; REVIEW, TUTORIAL
ISSN: 0003-987X
Country of Publication: UNITED STATES

Record 44 from database: MEDLINE
Return To Top
Return To Menu Position #40

Title: Ascorbate increases the number of low density lipoprotein receptors in cultured arterial smooth muscle cells.
Author: Aulinskas TH; Van der Westhuyzen DR; Coetzee GA
Address
Source: Atherosclerosis, 1983 May, 47:2, 159-71
Abstract: Receptor-mediated catabolism of low density lipoprotein (LDL) was increased 2-3-fold in down-regulated smooth muscle cells when the culture medium was supplemented with physiological concentrations of sodium ascorbate for 24 h. The enhanced degradation of LDL was associated with increased LDL receptor activity and LDL uptake. The increase in receptor activity was rapid, transient and inhibited by cycloheximide. Kinetic analysis of saturable binding indicated that ascorbate increased the number of LDL receptors but had no effect on the affinity of the lipoprotein for its receptor. Our data indicate that ascorbic acid may play a role in the regulation of plasma cholesterol levels by influencing LDL receptor number.
Language of Publication: English
Unique Identifier: 83256850

Return To Top
Return To Menu Position #40

MeSH Heading (Major): Ascorbic Acid|*PD; Lipoproteins, LDL|BL/*ME; Muscle, Smooth, Vascular|CY/*ME; Receptors, Cell Surface|AN/*DE
MeSH Heading: Animal; Aorta, Thoracic|ME; Cattle; Cells, Cultured; Endocytosis; Human; Kinetics; Mice; Rats; Support, Non-U.S. Gov't

Publication Type: JOURNAL ARTICLE
ISSN: 0021-9150
Country of Publication: NETHERLANDS

Record 45 from database: MEDLINE
Return To Top
Return To Menu Position #40

Title: Bioavailability in infants of iron from infant cereals: effect of dephytinization.
Author: Davidsson L; Galan P; Cherouvrier F; Kastenmayer P; Juillerat MA; Hercberg S; Hurrell RF
Address: NestlÆe Research Center Lausanne, Switzerland. davidsson@ilw.agrl.ethz.ch
Source: Am J Clin Nutr, 1997 Apr, 65:4, 916-20
Abstract: Iron bioavailability from an infant cereal made of wheat flour with a low extraction rate (70%) and cow milk was measured in infants by using a stable-isotope technique. A dephytinized infant cereal was prepared by adding commercial phytase during manufacture, resulting in degradation of 88% of the native phytic acid. Paired comparisons were made to evaluate the effect of phytic acid on iron bioavailability. Both infant cereals contained identical amounts of ascorbic acid and had a molar ratio of ascorbic acid to iron of 2:1. Iron was added as ferrous sulfate. No difference in iron bioavailability was observed in this study; the geometric mean was 8.7% (range: 3.8-16.9%) and 8.5% (range: 3.4-21.4%) from the cereal with native phytic acid (0.08% phytic acid) and the dephytinized cereal (0.01% phytic acid), respectively. Dephytinization of infant cereals containing a relatively low native phytic acid content and high amounts of ascorbic acid is thus unnecessary to ensure adequate bioavailability of iron.
Language of Publication: English
Unique Identifier: 97248967

Return To Top
Return To Menu Position #40

MeSH Heading (Major): Cereals|CH/*ME; Infant Food|*AN; Iron, Dietary|AN/*PK; Phytic Acid|AN/*ME; 6-Phytase|*PD
MeSH Heading: Ascorbic Acid|AN/ME; Biological Availability; Calcium|AN/ME; Comparative Study; Dietary Proteins|AN/ME; Enzyme-Linked Immunosorbent Assay|MT; Female; Ferritin|BL; Hemoglobins|AN; Human; Infant; Male

Publication Type: CLINICAL TRIAL; JOURNAL ARTICLE; RANDOMIZED CONTROLLED TRIAL
ISSN: 0002-9165
Country of Publication: UNITED STATES

Record 46 from database: MEDLINE
Return To Top
Return To Menu Position #40

Title: Fibroblast-migration in a wound model of ascorbic acid-supplemented three-dimensional culture system: the effects of cytokines and malotilate, a new wound healing stimulant, on cell-migration.
Author: Ohgoda O; Sakai A; Koga H; Kanai K; Miyazaki T; Niwano Y
Address: Research Center, Nihon Nohyaku Co., Ltd., Osaka, Japan.
Source: J Dermatol Sci, 1998 Jun, 17:2, 123-31
Abstract: To assess the migratory response of fibroblasts in vitro, normal human dermal fibroblasts (NHDF) were cultured in the presence of L-ascorbic acid 2-phosphate to induce a multilayered structure. Round wounds were made by punching, and the migratory response was evaluated by counting the number of migrating cells in the wounded areas. Collagenase activity in the culture-medium was then measured. When the wound model was treated with bFGF, IL-1 alpha or PDGF, the migratory response was facilitated with increased collagenase secretion. In contrast, treatment with TGF-beta reduced the migratory response and collagenase secretion. Since the multilayered structure is rich in collagenous matrix, degradation of the matrix by secreted collagenase is probably necessary for the cells to migrate into the wounded areas. Furthermore, malotilate, which is now under development as an agent for wound therapy, facilitated the migratory response of NHDF with increased collagenase secretion in this wound model, suggesting that the wound healing effect of malotilate is in part attributable to stimulated migration of fibroblasts to wounded areas subsequent to extracellular matrix-degradation.
Language of Publication: English
Unique Identifier: 98338682

Return To Top
Return To Menu Position #40

MeSH Heading (Major): Ascorbic Acid|*PD; Cytokines|*PD; Fibroblasts|*CY/*DE/EN; Malonates|*PD; Wound Healing|*DE/PH
MeSH Heading: Cell Movement|DE; Collagenases|ME/SE; Culture Media; Cytological Techniques; Human; Immunoblotting; Microscopy, Electron; Skin|CY/DE/EN; Stimulation, Chemical

Publication Type: JOURNAL ARTICLE
ISSN: 0923-1811
Country of Publication: IRELAND
CAS Registry/EC Number: EC 3.4.24.- (Collagenases); 0 (Culture Media); 0 (Cytokines); 0 (Malonates); 50-81-7 (Ascorbic Acid); 59937-28-9 (diisopropyl 1,3-dithiol-2-ylidenemalonate)

Record 47 from database: MEDLINE
Return To Top
Return To Menu Position #40

Title: Ascorbic acid specifically increases type I and type III procollagen messenger RNA levels in human skin fibroblast.
Author: Geesin JC; Darr D; Kaufman R; Murad S; Pinnell SR
Address: Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710.
Source: J Invest Dermatol, 1988 Apr, 90:4, 420-4
Abstract: In cultured human skin fibroblasts, ascorbic acid stimulates collagen production with no apparent change in the intracellular degradation of newly synthesized procollagen. To understand the basis for this effect, we measured the steady-state levels of type I and type III procollagen mRNAs in cells treated with ascorbic acid. A three- to fourfold increase in collagen synthesis was associated with a two- to threefold increase in the levels of mRNAs for both type I and type III procollagens. These effects of ascorbic acid are explained by a translational control linked either to procollagen gene transcription or mRNA degradation.
Language of Publication: English
Unique Identifier: 88170947

Return To Top
Return To Menu Position #40

MeSH Heading (Major): Ascorbic Acid|*PD; Procollagen|GE/*ME; RNA, Messenger|*ME; Skin|*CY
MeSH Heading: Collagen|BI; DNA|DU; Fibroblasts|DE/ME; Human; Male; Support, Non-U.S. Gov't; Support, U.S. Gov't, P.H.S.

Publication Type: JOURNAL ARTICLE
ISSN: 0022-202X
Country of Publication: UNITED STATES

Record 48 from database: MEDLINE
Return To Top
Return To Menu Position #40

Title: The interaction between two antioxidants, sodium ascorbate and gallic acid: radical intensity and apoptosis induction.
Author: Sakagami H; Satoh K
Address: First Department of Biochemistry, School of Medicine, Showa University, Tokyo, Japan.
Source: Anticancer Res, 1996 May, 16:3A, 1231-4
Abstract: ESR spectroscopy revealed that both the radical intensity and degradation rate of sodium ascorbate were increased with increasing pH. Gallic acid significantly reduced the radical intensity of sodium ascorbate, which in turn reduced the radical intensity of gallic acid. Sodium ascorbate inhibited the apoptosis-inducing activity of gallic acid, and gallic acid inhibited the intracellular incorporation of ascorbic acid. These data suggest that interaction between sodium ascorbate and gallic acid might modify their biological activity.
Language of Publication: English
Unique Identifier: 96273153

Return To Top
Return To Menu Position #40

MeSH Heading (Major): Antioxidants|*PD; Apoptosis|*DE; Ascorbic Acid|ME/*PD; Gallic Acid|ME/*PD
MeSH Heading: Drug Interactions; Electron Spin Resonance Spectroscopy; Free Radical Scavengers|PD; Free Radicals|ME; Human; HL-60 Cells|DE/ME; Kinetics; Support, Non-U.S. Gov't

Publication Type: JOURNAL ARTICLE
ISSN: 0250-7005
Country of Publication: GREECE

Record 49 from database: MEDLINE
Return To Top
Return To Menu Position #40

Title: Regulation of collagen biosynthesis by ascorbic acid: a review.
Author: Pinnell SR
Address
Source: Yale J Biol Med, 1985 Nov, 58:6, 553-9
Abstract: L-ascorbic acid is an essential cofactor for lysyl hydroxylase and prolyl hydroxylase, enzymes essential for collagen biosynthesis. In addition, L-ascorbic acid preferentially stimulates collagen synthesis in a manner which appears unrelated to the effect of L-ascorbic acid on hydroxylation reactions. This reaction is stereospecific and unrelated to intracellular degradation of collagen. The effect apparently occurs at a transcriptional or translational level, since L-ascorbic acid preferentially stimulates collagen-specific mRNA. In addition, it stimulates lysyl hydroxylase activity but inhibits prolyl hydroxylase activity in human skin fibroblasts in culture.
Language of Publication: English
Unique Identifier: 86182006

Return To Top
Return To Menu Position #40

MeSH Heading (Major): Ascorbic Acid|AA/*PD; Collagen|*BI/ME; Skin|DE/*ME
MeSH Heading: Cells, Cultured; Fibroblasts|DE/ME; Human; Hydroxylysine|BI; Hydroxyproline|BI; Kinetics; Procollagen-Lysine, 2-Oxoglutarate 5-Dioxygenase|ME; Procollagen-Proline Dioxygenase|ME; Support, Non-U.S. Gov't; Support, U.S. Gov't, P.H.S.

Publication Type: JOURNAL ARTICLE
ISSN: 0044-0086
Country of Publication: UNITED STATES

Record 50 from database: MEDLINE
Return To Top
Return To Menu Position #40
Return To Menu Position #50

Title: In vivo antineoplastic activity of ascorbic acid for human mammary tumor.
Author: Tsao CS; Dunham WB; Leung PY
Address: Linus Pauling Institute of Science and Medicine, Palo Alto, CA 94306.
Source: In Vivo, 1988 Mar, 2:2, 147-50
Abstract: The effect of ascorbic acid on the growth of human mammary tumor xenografts was investigated using the 6-day subrenal capsule assay method. The results showed that ascorbic acid (1 or 5 g/liter) administered in the drinking water significantly inhibited the growth of tumor fragments implanted beneath the renal capsule of immunocompetent mice. The results agree with other work carried out in animal experiments with animal tumors. Administration of ascorbic acid in the mouse diet did not affect the growth of the human mammary tumor fragments within the 6-day experimental period. Tumor growth was inhibited when mice were fed a diet containing ascorbic acid (50g/kg diet) together with cupric sulfate (18 or 90 mg/liter) in the drinking water. The results support the hypothesis that certain oxidation and degradation products of ascorbic acid are active antineoplastic agents for the human mammary carcinoma studied.
Language of Publication: English
Unique Identifier: 92135570

Return To Top
Return To Menu Position #40
Return To Menu Position #50

MeSH Heading (Major): Antineoplastic Agents|*; Ascorbic Acid|AD/*TU; Breast Neoplasms|*DT
MeSH Heading: Animal; Diet; Female; Human; Mice; Mice, Inbred Strains; Support, Non-U.S. Gov't; Transplantation, Heterologous

Publication Type: JOURNAL ARTICLE
ISSN: 0258-851X
Country of Publication: GREECE

Record 51 from database: MEDLINE
Return To Top
Return To Menu Position #40
Return To Menu Position #50

Title: Degradation of distinct forms of multimeric vitronectin by human fibroblasts.
Author: Wilkins Port CE; McKeown Longo PJ
Address: Cell and Molecular Biology Program and the Department of Physiology and Cell Biology (Mail Code 134), Neil Hellman Medical Research Building, Albany Medical College of Union University, 47 New Scotland Avenue, Albany, NY 12208, USA.
Source: Biochim Biophys Acta, 1998 Sep, 1404:3, 353-66
Abstract: The plasma protein vitronectin is thought to be an important regulator of extravascular plasminogen activation. In previous studies we have shown that a disulfide stabilized multimeric form of vitronectin is endocytosed and degraded by fibroblast cells (T.S. Panetti, P.J. McKeown-Longo, J. Biol. Chem. 268 (1993) 11988-11993; P.J. McKeown-Longo, T.S. Panetti, in: K.T. Preissner, S. Rosenblatt, C. Kost, J. Wegerhoff, D.F. Mosher (Eds.), Biology of Vitronectins and their Receptors, Elsevier Science Publishers, Amsterdam, 1993, pp. 111-118). The preparation of multimeric vitronectin used in these earlier studies was in the form of high molecular weight disulfide-bonded aggregates which were stable in sodium dodecyl sulfate (SDS). To address the question of whether vitronectin needed to be in the form of disulfide stabilized multimers in order to be endocytosed, a multimeric vitronectin, which was not disulfide stabilized, was prepared from vitronectin that had been treated with reducing agent and alkylated with iodoacetamide. The resulting protein migrated as a 65/75 kDa protein on SDS gels in the absence of reducing agent, confirming that this form of vitronectin was no longer stabilized into disulfide-bonded aggregates. However, the protein was still multimeric when analyzed by native gels and could be converted to SDS stable multimers by cross-linking agents. This result demonstrated that reduced and alkylated vitronectin aggregates into multimeric forms which are not stable in SDS. Similar to disulfide stabilized multimers, alkylated multimers of vitronectin bound to sulfated proteoglycans in the extracellular matrix and were endocytosed and degraded. Degradation of both forms of vitronectin was inhibited with arginine-glycine-aspartic acid peptides, an anti-alphavbeta5 antibody and heparin. Chloroquine and wortmannin were also able to inhibit degradation of both forms of vitronectin, indicating that both multimeric forms were following the same endocytic and degradative pathway. These results suggest that the organization of vitronectin into a multimeric form which will be recognized for endocytosis does not require disulfide bond stabilization. This study further suggests that recognition of vitronectin for endocytosis is dependent upon its conversion from a monomeric to a multivalent form (C.E. Wilkins-Port, P.J. McKeown-Longo, Mol. Biol. Cell 8:S:64A (1997).
Language of Publication: English
Unique Identifier: 98413024

Return To Top
Return To Menu Position #40
Return To Menu Position #50

MeSH Heading (Major): Fibroblasts|*ME; Vitronectin|AN/CH/*ME
MeSH Heading: Alkylation; Androstadienes|PD; Ascorbic Acid|PD; Cells, Cultured; Chloroquine|PD; Endocytosis; Heparin|PD; Human; Integrins|ME; Lysosomes|ME; Oligopeptides|PD; Proteoglycans|ME; Support, Non-U.S. Gov't; Support, U.S. Gov't, P.H.S.

Publication Type: JOURNAL ARTICLE
ISSN: 0006-3002
Country of Publication: NETHERLANDS

Record 52 from database: MEDLINE
Return To Top
Return To Menu Position #40
Return To Menu Position #50

Title: Role of hydrogen peroxide for cell death induction by sodium 5,6-benzylidene-L-ascorbate.
Author: Tajima M; Toguchi M; Kanda Y; Kunii S; Hosaka M; Arakawa H; Maeda M; Satoh K; Asano K; Kochi M; Sakagami H
Address: Department of Dental Pharmacology, Meikai University School of Dentistry, Saitama, Japan.
Source: Anticancer Res, 1998 May-Jun, 18:3A, 1697-702
Abstract: The role of hydrogen peroxide in the induction of cell death in human promyelocytic leukemic HL-60 cells by sodium 5,6-benzylidene-L-ascorbate (SBA) and its degradation product, ascorbic acid, was investigated. Millimolar concentrations of these compounds induced cell death, characterized by cell shrinkage, nuclear and internucleosomal DNA fragmentation, disappearance of microvilli and condensation of chromatin near the nuclear membrane. Catalase significantly reduced the cytotoxic activity of these compounds, whereas superoxide dismutase, nitric oxide (NO) generator, NO scavenger and NO synthase inhibitor were inactive, suggesting the possible role of H2O2. Determination of H2O2 with the peroxyoxalate chemiluminescence demonstrated that sodium ascorbate and SBA produced H2O2 in amounts necessary for cell death induction.
Language of Publication: English
Unique Identifier: 98338109

Return To Top
Return To Menu Position #40
Return To Menu Position #50

MeSH Heading (Major): Antineoplastic Agents|*TO; Antioxidants|*TO; Apoptosis|*DE; Ascorbic Acid|*AA/TO; Benzylidene Compounds|*TO; Hydrogen Peroxide|*PD; HL-60 Cells|CY/*DE/UL
MeSH Heading: Catalase|PD; Cell Nucleus|DE/PA; Cell Survival|DE; Chemiluminescence; DNA Fragmentation; Enzyme Inhibitors|PD; Guanidines|PD; Human; Kinetics; Nitric Oxide|PD; Nitric-Oxide Synthase|AI; Nucleosomes|DE/PA; NG-Nitroarginine Methyl Ester|PD; Superoxide Dismutase|PD

Publication Type: JOURNAL ARTICLE
ISSN: 0250-7005
Country of Publication: GREECE
CAS Registry/EC Number: EC 1.11.1.6 (Catalase); EC 1.14.13.39 (Nitric-Oxide Synthase); EC 1.15.1.1 (Superoxide Dismutase); 0 (Antineoplastic Agents); 0 (Antioxidants); 0 (Benzylidene Compounds); 0 (Enzyme Inhibitors); 0 (Guanidines); 0 (Nucleosomes); 10102-43-9 (Nitric Oxide); 20664-60-2 (zilascorb); 50-81-7 (Ascorbic Acid); 50903-99-6 (NG-Nitroarginine Methyl Ester); 7722-84-1 (Hydrogen Peroxide); 79-17-4 (pimagedine)

Record 53 from database: MEDLINE
Return To Top
Return To Menu Position #40
Return To Menu Position #50

Title: Effect of physiological fluids on radical intensity of sodium ascorbate and sodium 5,6-benzylidene-L-ascorbate.
Author: Satoh K; Ida Y; Asano K; Hisamitsu T; Inagaki M; Sho S; Kochi M; Tanaka T; Sakagami H
Address: Analysis Center, School of Pharmaceutical Sciences, Showa University, Tokyo, Japan.
Source: Anticancer Res, 1997 Nov, 17:6D, 4457-61
Abstract: The effect of various physiological fluids on the radical intensity of sodium ascorbate and sodium 5,6-benzylidene-L-ascorbate (SBA) was investigated using ESR spectroscopy. Blood from various animals did not significantly affect the radical intensity of both ascorbates, whereas the corresponding plasma fractions significantly enhanced the radical intensity. This suggests that some populations of blood cells might modify the interaction between plasma components and ascorbates. Saliva contained labile substance(s) which effectively reduced the ascorbate radical intensity. HPLC demonstrated the presence of endogenous ascorbate in rat liver and brain homogenates. When sodium ascorbate or SBA was incubated with any of these homogenates, their radical intensity was synergistically enhanced, but abruptly declined without any apparent ascorbate degradation. Incubation with homogenates elevated the radical intensity of SBA up to the level significantly higher than that of sodium ascorbate. The present data suggest that antitumor action of SBA might be mediated via the accelerated production of ascorbate radical in the target organ.
Language of Publication: English
Unique Identifier: 98155654

Return To Top
Return To Menu Position #40
Return To Menu Position #50

MeSH Heading (Major): Antineoplastic Agents|BL/CH/*PK; Ascorbic Acid|*AA/BL/CH/*PK; Benzylidene Compounds|BL/CH/*PK; Brain|*ME; Liver|*ME; Saliva|*PH
MeSH Heading: Animal; Comparative Study; Dogs; Free Radicals|AN; Guinea Pigs; Human; Mice; Mice, Inbred BALB C; Rabbits; Rats; Rats, Inbred F344

Publication Type: JOURNAL ARTICLE
ISSN: 0250-7005
Country of Publication: GREECE

Record 54 from database: MEDLINE
Return To Top
Return To Menu Position #50

Title: Ultraviolet A decreases epidermal growth factor (EGF) processing in cultured human fibroblasts and keratinocytes: inhibition of EGF-induced diacylglycerol formation.
Author: Djavaheri Mergny M; Mazière C; Santus R; Dubertret L; Mazière JC
Address: Laboratoire de Physico-Chimie de l'Adaptation Biologique, INSERM U312, MusÆeum National d'Histoire Naturelle de Paris, France.
Source: J Invest Dermatol, 1994 Feb, 102:2, 192-6
Abstract: The binding, uptake, and degradation of epidermal growth factor (EGF) has been studied in MRC5 human fibroblasts and NCTC 2544 human keratinocytes following ultraviolet A (UVA) irradiation at doses up to 18.9 J/cm2, which are not lethal to cells under our experimental conditions. A dose-dependent reduction in EGF binding was observed, with an approximately 75% decrease at the maximal studied UVA dose. At lower doses (6 to 12 J/cm2), EGF binding was more affected by ultraviolet A in fibroblasts than in keratinocytes. In both cell types, this effect of UVA appeared to be related to a reduction of the affinity of the EGF receptor for EGF. Kinetic studies by pulse-chase experiments indicated that EGF is more rapidly internalized by keratinocytes than by fibroblasts, and that UVA exposure resulted in a slower decay of EGF intracellular content. A 24-h pretreatment of cells with 5 x 10(-5) M vitamin E strongly reduced the appearance of light-induced lipid peroxidation products, measured via assay of thiobarbituric acid reactive substances formation, but only partially prevented the UVA-induced alterations of EGF processing by cells. Finally, UVA exposure almost completely abolished the EGF-induced increase in diacylglycerol production from 14C-arachidonic acid-labeled lipids in both cell types. These results demonstrate that UVA radiation induces important changes in EGF processing and could participate in the light-induced degenerative processes of the skin.
Language of Publication: English
Unique Identifier: 94149290

Return To Top
Return To Menu Position #50

MeSH Heading (Major): Diglycerides|*ME; Epidermal Growth Factor-Urogastrone|*ME/*PH; Fibroblasts|CY/*ME/RE; Keratinocytes|CY/*ME/RE; Ultraviolet Rays|*
MeSH Heading: Antioxidants|PD; Arachidonic Acids|PD; Carbon Radioisotopes; Cell Line; Dose-Response Relationship, Radiation; Enzyme Activation; Human; Phospholipase C|ME; Support, Non-U.S. Gov't; Time Factors; Vitamin E|PD

Publication Type: JOURNAL ARTICLE
ISSN: 0022-202X
Country of Publication: UNITED STATES

Record 55 from database: MEDLINE
Return To Top
Return To Menu Position #50

Title: Iron deficiency among pregnant Pakistanis in Norway and the content of phytic acid in their diet.
Author: Brunvand L; Henriksen C; Larsson M; Sandberg AS
Address: Department of Paediatrics, UllevÁal Hospital, Oslo, Norway.
Source: Acta Obstet Gynecol Scand, 1995 Aug, 74:7, 520-5
Abstract: BACKGROUND. To test the hypothesis that iron deficiency is more common among pregnant Pakistani than pregnant Norwegian women in Oslo; and to determine whether differences in the diet cn explain some of the differences in stored iron. METHODS. A cross sectional study in the 18th week of pregnancy. Thirty-eight Pakistani women and 38 Norwegian women referred to routine ultrasound examination at Aker and UllevÁl Hospitals in Oslo participated. Analysis was undertaken of phytate (inositol hexaphosphate) and its degradation products in bread and chapatti. RESULTS. Twenty-six (68%) of the Pakistani and six (17%) of the Norwegian women had ferritin levels below 12 micrograms/l and a highly significant difference in serum ferritin was found between the groups (p < 0.001). Only one of the Pakistani and seven of the Norwegian women were supplemented with iron and there were no significant differences in the dietary intake of hem iron, non-hem iron, organic fiber, tea, ascorbic acid, meat or cereals. The content of inositol hexaphosphate (phytate) and inositol pentaphosphate, well known inhibitors of iron absorption, were measured in bread and chapatti and the estimated dietary intake was much higher in the Pakistani group, mean (95% CI) was 1175 mumol/day (933-1417) and 507 mumol/day (417-597) respectively, p < 0.001. CONCLUSIONS. Iron deficiency seems to be far more common among pregnant Pakistanis in Norway than among pregnant Norwegians. We speculate that the main reasons for this are a combination of a higher parity and a less common use of iron supplementation in pregnancy in the Pakistani group, and a higher content of phytate in the Pakistani diet.
Language of Publication: English
Unique Identifier: 95343737

Return To Top
Return To Menu Position #50

MeSH Heading (Major): Anemia, Iron-Deficiency|*EH; Food Habits|*; Phytic Acid|*AD; Pregnancy Complications, Hematologic|*EH
MeSH Heading: Adult; Comparative Study; Cross-Sectional Studies; Female; Ferritin|BL; Hemoglobins|AN; Human; Iron|AD/TU; Norway; Pakistan|EH; Parity; Pregnancy|BL

Publication Type: JOURNAL ARTICLE
ISSN: 0001-6349
Country of Publication: DENMARK

Record 56 from database: MEDLINE
Return To Top
Return To Menu Position #50

Title: Efficacy of topical treatment of pigmentation skin disorders with plant hydroquinone glucosides as assessed by quantitative color analysis.
Author: Clarys P; Barel A
Address: Algemene en Biologische Scheikunde, Faculteit voor Lichamelijke Opvoeding en Kinesitherapie, Vrije Universiteit Brussel, Belgium.
Source: J Dermatol, 1998 Jun, 25:6, 412-4
Abstract: Hydroquinone is a well known reagent used in the treatment of pigmentation disorders. The instability of the quinones and the required active concentration make topical treatment rather difficult. We tested the efficacy of an ascorbate-phytohydroquinone complex that inhibits the synthesis of melanin and promotes the degradation of the existing melanin. Lentigo senile lesions were evaluated before and after 1 month of treatment. Objective skin color evaluation was performed instrumentally. After one month of treatment, a clear depigmentation of the macules was measured. None of the volunteers reported any side effects from the prolonged treatment with the hydroquinone containing product.
Language of Publication: English
Unique Identifier: 98339952

Return To Top
Return To Menu Position #50

MeSH Heading (Major): Dermatologic Agents|AD/*TU; Glucosides|AD/*TU; Lentigo|*DT
MeSH Heading: Administration, Cutaneous; Aged; Aged, 80 and over; Apiaceae; Ascorbic Acid|AD/TU; Benzoyl Peroxide|TU; Citrus; Colorimetry; Drug Combinations; Female; Follow-Up Studies; Human; Hydroquinones|AD/TU; Male; Melanins|AI/ME; Middle Age; Oils, Volatile|TU; Oxyquinoline|TU; Plant Extracts|TU; Skin Pigmentation|DE

Publication Type: JOURNAL ARTICLE
ISSN: 0385-2407
Country of Publication: JAPAN
CAS Registry/EC Number: 0 (hydroquinoneglucoside); 0 (Dermatologic Agents); 0 (Drug Combinations); 0 (Glucosides); 0 (Hydroquinones); 0 (Melanins); 0 (Oils, Volatile); 0 (Plant Extracts); 123-31-9 (hydroquinone); 148-24-3 (Oxyquinoline); 50-81-7 (Ascorbic Acid); 78515-96-5 (quinoderm); 94-36-0 (Benzoyl Peroxide)

Record 57 from database: MEDLINE
Return To Top
Return To Menu Position #50

Title: UVA irradiation of human lens proteins produces residual oxidation of ascorbic acid even in the presence of high levels of glutathione.
Author: Ortwerth BJ; Coots A; James HL; Linetsky M
Address: Mason Eye Institute, University of Missouri, Columbia, Missouri 65212, USA.
Source: Arch Biochem Biophys, 1998 Mar, 351:2, 189-96
Abstract: The oxidation products of ascorbic acid (AscH-) can rapidly glycate and crosslink lens proteins in vitro, producing fluorophores and browning products similar to those present in cataractous lenses. The accumulation of AscH- oxidation products, however, would largely be prevented by the millimolar levels of glutathione (GSH) present in human lens. Here we investigate whether protein aggregation could allow the oxidation of AscH- by UVA-induced reactive oxygen species in the presence of physiological levels of GSH. The metal-catalyzed oxidation of 1.0 mM AscH- by 50 microM Cu(II) was almost complete after 1 h, but no oxidation was seen in the presence of GSH concentrations as low as 0.5 mM. UVA irradiation of protein aggregates from human lens, which accumulated more than 2.0 mM singlet oxygen after 1 h, caused a 50-60% oxidation of 1.0 mM AscH-. The addition of 204 mM GSH, however, decreased AscH- oxidation by less than half, and 30% of the AscH- was oxidized even in the presence of 15 mM GSH. This diminished protection may be due, in part, to the ability of AscH-, but not GSH, to penetrate to the sites of singlet oxygen generation located within the protein. Consistent with this hypothesis, greater GSH protection was seen when a proteolytic digest of the human proteins was subjected to the same irradiation or when singlet oxygen was chemically generated from 3-(4-methyl-1-naphthyl)propionic acid endoperoxide (MNPAE) at 37 degrees C in the medium. The addition of 50 microM Cu(II) had no effect on the rate of degradation of dehydroascorbic acid (DHA). Singlet oxygen, either UVA- or MNPAE-generated, increased the rate of DHA loss. This secondary oxidation of DHA by singlet oxygen would allow the accumulation of AscH- oxidation products was not reducible by GSH. Therefore, the data presented here argue that the protein aggregation seen in older human lenses may permit oxidized AscH--induced crosslinking to occur even at physiological GSH levels.
Language of Publication: English
Unique Identifier: 98215006

Return To Top
Return To Menu Position #50

MeSH Heading (Major): Ascorbic Acid|*ME; Crystallins|PH/*RE; Glutathione|*PD
MeSH Heading: Aging|PH; Copper|ME; Cross-Linking Reagents|ME; Dehydroascorbic Acid|ME; Glycosylation|RE; Human; Kinetics; Oxidation-Reduction; Peroxides|ME; Reactive Oxygen Species|ME; Support, Non-U.S. Gov't; Support, U.S. Gov't, P.H.S.; Ultraviolet Rays

Publication Type: JOURNAL ARTICLE
ISSN: 0003-9861
Country of Publication: UNITED STATES

Record 58 from database: MEDLINE
Return To Top
Return To Menu Position #50

Title: Enhancement of cytotoxic activity of ascorbate by Acer nikoense Maxim. Extracts.
Author: Sakagami H; Anzai S; Goto S; Takeda M
Address: Department of Dental Pharmacology, Meikai University School of Dentistry, Saitama, Japan.
Source: Anticancer Res, 1997 Nov, 17:6D, 4453-6
Abstract: Millimolar concentrations of ascorbic acid or sodium ascorbate induced cytotoxicity against human glioblastoma T98G cells. Addition of hot water and sodium hydroxide extracts of the bark of Acer nikoense Maxim. synergistically enhanced the cytotoxic activity of ascorbate. Human peripheral blood lymphocytes and polymorphonuclear cells were relatively resistant to ascorbate, the Acer nikoense Maxim. extract, or a combination of them. The extracts stimulated the degradation of ascorbates via ascorbyl radical production, in parallel with their ability to stimulate the cytotoxic activity of ascorbate. The results suggest the medicinal efficacy of the Acer nikoense Maxim. extracts.
Language of Publication: English
Unique Identifier: 98155653

Return To Top
Return To Menu Position #50

MeSH Heading (Major): Antineoplastic Agents|*; Lymphocytes|CY/*DE/PH; Neutrophils|CY/*DE/PH; Plant Extracts|*TO; Plants, Medicinal|*; Trees|*
MeSH Heading: Ascorbic Acid|ME/PD; Cell Survival|DE; Glioblastoma; Human; In Vitro; Plant Stems; Support, Non-U.S. Gov't; Tumor Cells, Cultured

Publication Type: JOURNAL ARTICLE
ISSN: 0250-7005
Country of Publication: GREECE

Record 59 from database: MEDLINE
Return To Top
Return To Menu Position #50

Title: Ascorbic acid promotes prostanoid release in human lung parenchyma.
Author: Fann YD; Rothberg KG; Tremml PG; Douglas JS; DuBois AB
Address
Source: Prostaglandins, 1986 Feb, 31:2, 361-8
Abstract: Ascorbic acid reduces airway reactivity to inhaled bronchoconstrictor agents in man and guinea pigs. The precise mechanism(s) responsible for this effect are unknown, but in both species an acute indomethacin treatment reverses the action of the ascorbic acid. To determine if ascorbic acid promotes prostanoid synthesis and/or inhibits degradation, human lung parenchymal slices (100-200 mg) were incubated for 60 minutes in oxygenated Tyrode's solution alone or with sodium ascorbate (0.001 M-1 M) and/or methacholine (1 microM-100 microM) and/or indomethacin (0.17 microM-17 microM). Aliquots of the incubation medium were assayed by radioimmunoassay for PGE2, PGF2 alpha, thromboxane B2 and 6-keto-PGF1 alpha. Ascorbic acid increased the accumulation of all four prostanoids in the incubation medium, especially thromboxane B2 and 6-keto-PGF1 alpha. This stimulatory effect of ascorbic acid was concentration-dependent and was inhibited by indomethacin. We conclude that ascorbic acid can alter prostanoid generation by human lung tissue and this effect may, in part, explain its antibronchoconstrictor activity in man.
Language of Publication: English
Unique Identifier: 86178505

Return To Top
Return To Menu Position #50

MeSH Heading (Major): Ascorbic Acid|*PD; Lung|CY/DE/*SE; Prostaglandins|*SE
MeSH Heading: Female; Human; Kinetics; Lung Neoplasms|SU; Male; Methacholine Compounds|PD; Smoking

Publication Type: JOURNAL ARTICLE
ISSN: 0090-6980
Country of Publication: UNITED STATES

Record 60 from database: MEDLINE
Return To Top
Return To Menu Position #50
Return To Menu Position #60

Title: Mechanism of interferon-gamma action. Characterization of indoleamine 2,3-dioxygenase in cultured human cells induced by interferon-gamma and evaluation of the enzyme-mediated tryptophan degradation in its anticellular activity.
Author: Takikawa O; Kuroiwa T; Yamazaki F; Kido R
Address: Department of Biochemistry, Wakayama Medical College, Japan.
Source: J Biol Chem, 1988 Feb, 263:4, 2041-8
Abstract: Induction by interferon-gamma of indoleamine 2,3-dioxygenase (a tryptophan degradation enzyme) was examined with 11 human cell lines. The enzyme induction was demonstrated in 7 of the 11 cell lines. The induced enzyme in each of the 7 cell lines was identical to the enzyme purified from human placenta, as evidenced by immunoblot analysis with a monoclonal antibody specific to the placental one. The extent of the induction varied largely with the cell line; a relatively high induction was observed with HEL (lung fibroblasts), NY (osteosarcoma), and A-431 (epidermoid carcinoma). The enzyme induction was dependent on the concentration of interferon-gamma and occurred 12-18 h after addition of interferon-gamma to the cultures. Interferon-alpha or -beta was completely ineffective in this induction. Interferon-gamma inhibited the growth of the 7 cell lines observed with the enzyme induction, and this growth inhibition was accompanied with a complete deletion of tryptophan (less than 1 microM) in the culture medium by the induction of the enzyme. For two of these cell lines, the inhibition was partially reversed by an addition of exogenous tryptophan to the medium not to be depleted. These findings indicated that the growth inhibition by interferon-gamma was in part explained by the tryptophan depletion in the medium caused by the enzyme induction.
Language of Publication: English
Unique Identifier: 88115334

Return To Top
Return To Menu Position #50
Return To Menu Position #60

MeSH Heading (Major): Interferon Type II|*PD; Oxygenases|*ME; Tryptophan|*ME
MeSH Heading: Ascorbic Acid|ME; Carcinoma, Squamous Cell|EN; Enzyme Induction; Human; Immunosorbent Techniques; Lung|DE; Methylene Blue|ME; Osteosarcoma|EN; Recombinant Proteins|PD; Support, Non-U.S. Gov't; Tryptophan Oxygenase|ME; Tumor Cells, Cultured|DE

Publication Type: JOURNAL ARTICLE
ISSN: 0021-9258
Country of Publication: UNITED STATES

Record 61 from database: MEDLINE
Return To Top
Return To Menu Position #50

Return To Menu Position #60

Title: The effect of ascorbic acid and ferric ammonium citrate on iron uptake and storage in lens epithelial cells.
Author: Goralska M; Harned J; Fleisher LN; McGahan MC
Address: Department of Anatomy, Physiology and Radiology, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, 27606, USA.
Source: Exp Eye Res, 1998 Jun, 66:6, 687-97
Abstract: Ferritin is the major intracellular iron storage protein which has been shown to protect cells against oxidative damage. Recent reports that an inherited abnormality in human ferritin synthesis is associated with early bilateral cataracts underscore the importance of understanding ferritin synthesis and iron storage in lens epithelial cells. We previously demonstrated that ascorbic acid greatly increases de novo synthesis of ferritin in lens epithelial cells. The objectives of the present study were to determine: (1) the effects of ascorbic acid and ferric ammonium citrate on iron uptake by canine lens epithelial cells from iron bound to transferrin and from ferric chloride and (2) the incorporation of this element into ferritin. Iron uptake by lens epithelial cells from 59ferric chloride was 20 times higher than from 59iron-transferrin and iron deposition into ferritin was 8-fold higher when 59ferric chloride was the source. Ascorbic acid had a stimulatory effect on iron uptake from transferrin and on incorporation of this element into ferritin. The ascorbic acid-induced increase of iron uptake required de novo protein synthesis but not specifically de novo ferritin biosynthesis. Although ferritin is not directly involved in iron uptake, the level of ferritin protein could control the pool of intracellular iron. The present results indicate that iron homeostasis in lens epithelial cells is affected mainly by changes in apoferritin synthesis, which is greatly stimulated by ascorbic acid, rather than by altering the rate of protein degradation, which is very slow in these cells under all circumstances. Ferric ammonium citrate activates iron uptake from transferrin in a wide range of cell lines by generation of free radicals. Ferric ammonium citrate also increased iron uptake from Tf in lens epithelial cells. Ferric ammonium citrate treated cells incorporated 5 times more iron and deposited 2 times more iron into ferritin than control cells. Increased incorporation of iron into ferritin was due to ferric ammonium citrate-induced stimulation of de novo ferritin synthesis rather than an increased rate of iron deposition into pre-existing ferritin. Ferric ammonium citrate had a different effect on iron uptake from ferric chloride; total iron uptake was not significantly increased while deposition into ferritin was significantly decreased. These results demonstrate that iron homeostasis in lens epithelial cells is regulated by ascorbic acid and by changes in the rate of de novo ferritin synthesis. In addition, the differences in iron uptake from transferrin and ferric chloride and its subsequent incorporation into ferritin suggests that the mechanisms by which iron is incorporated into ferritin are source dependent. Copyright 1998 Academic Press.
Language of Publication: English
Unique Identifier: 98324937

Return To Top
Return To Menu Position #50
Return To Menu Position #60

MeSH Heading (Major): Ammonium Compounds|*PD; Apoferritin|*BI; Ascorbic Acid|*PD; Ferric Compounds|ME/*PD; Lens, Crystalline|*ME
MeSH Heading: Animal; Cells, Cultured; Dogs; Epithelial Cells|ME; Homeostasis; Human; Infant, Newborn; Iron Radioisotopes|ME; Support, Non-U.S. Gov't; Support, U.S. Gov't, P.H.S.; Transferrin|ME

Publication Type: JOURNAL ARTICLE
ISSN: 0014-4835
Country of Publication: ENGLAND
CAS Registry/EC Number: 0 (Ammonium Compounds); 0 (Ferric Compounds); 0 (Iron Radioisotopes); 11096-37-0 (Transferrin); 1185-57-5 (ferric ammonium citrate); 50-81-7 (Ascorbic Acid); 7705-08-0 (ferric chloride); 9013-31-4 (Apoferritin)

Record 62 from database: MEDLINE
Return To Top
Return To Menu Position #50

Return To Menu Position #60

Title: Administration of antioxidant vitamins does not alter plasma fibrinolytic activity in subjects with central obesity.
Author: Rifici VA; Schneider SH; Chen Y; Khachadurian AK
Address: Department of Medicine, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, New Brunswick 08903-0019, USA.
Source: Thromb Haemost, 1997 Sep, 78:3, 1111-4
Abstract: In vitro studies suggest that oxidized low density lipoprotein inhibits fibrinolysis by stimulating the production of plasminogen activator inhibitor -1 (PAI). We assessed the effects of dietary antioxidant vitamins for four weeks on three indices of copper mediated oxidation of very low and low density lipoproteins (VLDL+LDL) and plasma fibrinolytic activities in 15 male subjects with central obesity, a condition associated with increased PAI activity. Vitamin administration resulted in a decrease in production of thiobarbituric acid reactive substances from 29.3 +/- 3.9 to 13.6 +/- 3.5 nmoles/mg VLDL + LDL protein (mean +/- SE, p <0.003), an increase in the lag phase of conjugated diene formation from 94.8 +/- 5.5 to 225.0 +/- 31.9 min (p <0.001) and an increase in reactivity of lysine residues from 73.6% +/- 4.8% to 86.8% +/- 3.6% (p <0.034) demonstrating a reduction in the susceptibility of the lipoproteins to oxidation. However, antioxidant vitamins had no effect on plasma PAI activity, PAI antigen, tissue-type plasminogen activator activity and antigen, fibrinogen and fibrin degradation products. These results do not support the hypothesis that lipoprotein oxidation is a significant cause of impaired fibrinolysis in men with central obesity.
Language of Publication: English
Unique Identifier: 97452348

Return To Top
Return To Menu Position #50

Return To Menu Position #60

MeSH Heading (Major): Antioxidants|*PD; Fibrinolysis|*DE; Obesity|*PP; Vitamins|*PD
MeSH Heading: Ascorbic Acid|BL; Blood Glucose|AN; Human; Lipoproteins, LDL|BL; Lipoproteins, VLDL|BL; Male; Plasminogen Activator Inhibitor 1|BL; Support, Non-U.S. Gov't; Tissue Plasminogen Activator|ME; Trinitrobenzenesulfonic Acid|AN

Publication Type: JOURNAL ARTICLE
ISSN: 0340-6245
Country of Publication: GERMANY

Record 63 from database: MEDLINE
Return To Top
Return To Menu Position #50
Return To Menu Position #60

Title: DNA- and protein-scission activities of ascorbate in the presence of copper ion and a copper-peptide complex.
Author: Chiou SH
Address
Source: J Biochem (Tokyo), 1983 Oct, 94:4, 1259-67
Abstract: L-Ascorbic acid, when combined with either copper(II) ion or a copper(II)-tripeptide complex, extensively cleaved several viral DNAs and proteins under in vitro conditions. Neither ascorbate nor copper tripeptide (Cu2+-diglycyl-L-histidine) alone caused any apparent changes on these molecules. Various transition metal ions and reducing agents were examined under comparable conditions to determine the basic requirements for both DNA degradation and protein scission activities. Copper and iron are the two most effective transition metal ions examined that exhibit these activities in the presence of ascorbate. The addition of catalase, but not superoxide dismutase, can partially inhibit the scission of DNA in vitro, suggesting that H2O2 may be involved in these activities. Among the various reducing agents tested, ascorbate was most effective in causing DNA scission and protein cleavage, corroborating the possible role of H2O2 in the cleavage reactions. One of the products of the reactions of copper/ascorbate is probably the hydroxyl radical generated from H2O2, which can be formed from the oxidation of ascorbate.
Language of Publication: English
Unique Identifier: 84087780

Return To Top
Return To Menu Position #60

MeSH Heading (Major): Ascorbic Acid|*; Copper|*; DNA|*; DNA, Viral|*ME; Oligopeptides|*
MeSH Heading: Chelating Agents; Human; Metals; Proteins|ME; Serum Albumin|ME; Transferrin|ME

Publication Type: JOURNAL ARTICLE
ISSN: 0021-924X
Country of Publication: JAPAN

Record 64 from database: MEDLINE
Return To Top
Return To Menu Position #60

Title: Gas chromatographic/mass spectrometric measurement of ascorbic acid and analysis of ascorbic acid degradation in solution.
Author: Deutsch JC
Address: Department of Medicine, University of Colorado Health Sciences Center, Denver 80220, USA.
Source: Methods Enzymol, 1997, 279:, 13-24
Abstract: L-Ascorbic acid, DHA, and the oxidized products derived from AA can be accurately measured using GC/MS. Owing to the complex nature of the reactions through which AA proceeds, we believe that GC/MS is currently the procedure of choice in making AA-related measurements. The methods described are useful in defining reactions involving AA. The methods may indicate in vivo oxidative injury and may allow the use of AA-derived products to determine if antioxidant modulations are effective.
Language of Publication: English
Unique Identifier: 97355057

Return To Top
Return To Menu Position #60

MeSH Heading (Major): Ascorbic Acid|*AN/CH; Chromatography, Gas|*MT; Spectrum Analysis, Mass|*MT
MeSH Heading: Animal; Human

Publication Type: JOURNAL ARTICLE; REVIEW; REVIEW, TUTORIAL
ISSN: 0076-6879
Country of Publication: UNITED STATES

Record 65 from database: MEDLINE
Return To Top
Return To Menu Position #60

Title: Ascorbic acid as an antioxidant in measurements of catecholamines in plasma.
Author: Hugh D; Grennan A; Abugila MA; Weinkove C
Address
Source: Clin Chem, 1987 Apr, 33:4, 569-71
Abstract: Sodium metabisulfite, commonly used to prevent the oxidation of catecholamines during extraction from plasma onto alkaline alumina, does not prevent their subsequent degradation in acetic acid eluates. However, ascorbic acid, a potent antioxidant, is extracted with the catecholamines onto the alumina and prevents such destruction. However, ascorbic acid may interfere with the electrochemical measurement of catecholamines, unless sequential oxidation and reduction are used. Other methods of minimizing catecholamine oxidation in acetic acid eluates include refrigerating at 4 degrees C and capping the sample vials to exclude atmospheric oxygen.
Language of Publication: English
Unique Identifier: 87160007

Return To Top
Return To Menu Position #60

MeSH Heading (Major): Antioxidants|*BL; Ascorbic Acid|*BL; Catecholamines|*BL
MeSH Heading: Aluminum Oxide; Chromatography, High Pressure Liquid; Dopamine|AA/BL; Electrochemistry; Epinephrine|BL; False Negative Reactions; Human; Norepinephrine|BL; Solutions; Sulfites

Publication Type: JOURNAL ARTICLE
ISSN: 0009-9147
Country of Publication: UNITED STATES

Record 66 from database: MEDLINE
Return To Top
Return To Menu Position #60

Title: Enhancement of radical intensity and cytotoxic activity of ascorbate by hyperthermia.
Author: Satoh K; Sakagami H; Nakamura K
Address: Analysis Center, School of Pharmaceutical Sciences, Showa University, Tokyo, Japan.
Source: Anticancer Res, 1996 Sep, 16:5A, 2987-91
Abstract: ESR spectroscopy revealed that the radical intensity of sodium ascorbate and ascorbic acid was significantly higher under hyperthermic conditions. The enhancement of ascorbyl radical intensity was coupled with the accelerated degradation of ascorbate and cytotoxicity induction against human leukemic and glioblastoma cell lines. Sodium ascorbate produced higher ascorbyl radical intensity and more potent cytotoxicity, as compared with ascorbic acid. These data demonstrate that ascorbic acid does not inhibit, but rather stimulates the cytotoxic action of hyperthermia. The combination of hyperthermia and ascorbate treatment might produce higher antitumor activity.
Language of Publication: English
Unique Identifier: 97074990

Return To Top
Return To Menu Position #60

MeSH Heading (Major): Ascorbic Acid|*ME/PD; Hyperthermia, Induced|*
MeSH Heading: Dose-Response Relationship, Drug; Free Radicals|ME/PD; Human; HL-60 Cells|DE; Temperature; Tumor Cells, Cultured|DE

Publication Type: JOURNAL ARTICLE
ISSN: 0250-7005
Country of Publication: GREECE

Record 67 from database: MEDLINE
Return To Top
Return To Menu Position #60

Title: Lack of correlation between TBARS production and PUFA degradation during incubation of membrane erythrocytes in an OH. (Fe2+/H2O2) generator system.
Author: Tallineau C; Barrier L; Fauconneau B; Guettier A; Piriou A
Address: Institut des XÆenobiotiques et Laboratoire de Biochimie, FacultÆe de MÆedecine et de Pharmacie, Poitiers, France.
Source: Biol Trace Elem Res, 1995 Jan, 47:1-3, 3-7
Abstract: We investigated the effects of an OH. (Fe2+/H2O2) generator system on erythrocyte membrane, particularly the time-course of lipid peroxidation as estimated by measurement of conjugated dienes, thiobarbituric reactive substances (TBARS), lipofuscin-like pigments, and alpha-tocopherol. Polyunsaturated fatty acids (PUFAs), especially arachidonic acid (20:4 omega 6) and docosahexenoic acid (22:6 omega 3), were also measured. Erythrocyte membranes were suspended in phosphate buffer containing Fe2+ (200 microM) and H2O2 (1.42 mM), and incubated in a shaking water bath at 37 degrees C. Initially, there was an increase in TBARS and lipofuscin-like pigments, two well-known end products of PUFA oxidative degradation, whereas PUFAs remained unchanged (incubation time: 1 h). After two or more hours of incubation, marked lipid peroxidation was noted, with the appearance of conjugated dienes and a decrease of PUFAs, indicating that lipid peroxidation had occurred after a lag phase during which TBARS were not produced from PUFAs. This suggests that another OH. target was involved.
Language of Publication: English
Unique Identifier: 95298508

Return To Top
Return To Menu Position #60

MeSH Heading (Major): Erythrocyte Membrane|*ME; Fatty Acids, Unsaturated|*BL; Hydroxyl Radical|*PD; Thiobarbituric Acid Reactive Substances|*ME
MeSH Heading: Arachidonic Acid|BL; Docosahexaenoic Acids|BL; Human; Hydrogen Peroxide; Iron; Kinetics; Lipofuscin|BL; Vitamin E|BL

Publication Type: JOURNAL ARTICLE
ISSN: 0163-4984
Country of Publication: UNITED STATES

Record 68 from database: MEDLINE
Return To Top
Return To Menu Position #60

Title: Ascorbic acid and ferritin catabolism.
Address
Source: Nutr Rev, 1989 Jul, 47:7, 218-9
Abstract: Ascorbic acid blocks the degradation of cytoplasmic ferritin by reducing lysosomal autophagy of the protein.
Language of Publication: English
Unique Identifier: 89314611

Return To Top
Return To Menu Position #60

MeSH Heading (Major): Ascorbic Acid|*ME; Ferritin|*ME
MeSH Heading: Human; In Vitro

Publication Type: JOURNAL ARTICLE; REVIEW; REVIEW, TUTORIAL
ISSN: 0029-6643
Country of Publication: UNITED STATES

Record 69 from database: MEDLINE
Return To Top
Return To Menu Position #60
Return To Menu Position #70

Title: Ability of retinoic and ascorbic acid to interfere with the binding of benzo(a)pyrene to DNA in explants from donors with bronchial cancer.
Author: Bodo M; Todisco T; Pezzetti F; Dottorini M; Moggi L; Becchetti E
Address: Dipartimento di Medicina Sperimentale e Scienze Biochimiche, UniversitÄa di Perugia, Italia.
Source: Oncology, 1989, 46:3, 178-82
Abstract: The capability of ascorbic acid (AA) and transretinoic acid (RA) to interfere with 3H-benzo(a)pyrene [B(a)P] binding to DNA has been evaluated in cultured bronchial mucosa explants from patients with bronchial cancer. The results show that the DNA-bound 3H-B(a)P is smaller in treated cultures than in controls. To explain this finding, it is proposed that AA, acting as antioxidant, inhibits the oxidative degradation of B(a)P, and that RA, a lipophilic compound interacting with the lipid components of mixed function oxidases, could modify the activities of these enzymes. Both vitamins decrease the concentration of ultimate carcinogen metabolites, which can interact with DNA. Furthermore, the treatment with RA does not increase DNA synthesis, while AA inhibits 3H-thymidine incorporation.
Language of Publication: English
Unique Identifier: 89239322

Return To Top
Return To Menu Position #60
Return To Menu Position #70

MeSH Heading (Major): Antineoplastic Agents, Combined|*; Ascorbic Acid|*PD; Benzo(a)pyrene|*ME/PK; Bronchi|*ME; Bronchial Neoplasms|*ME; DNA|*ME; Tretinoin|*PD
MeSH Heading: Cell Division; Drug Synergism; Human; Organ Culture; Support, Non-U.S. Gov't; Thymidine|DU

Publication Type: JOURNAL ARTICLE
ISSN: 0030-2414
Country of Publication: SWITZERLAND

Record 70 from database: MEDLINE
Return To Top
Return To Menu Position #60
Return To Menu Position #70

Title: Quality control of protein C: protein C synthesized in the presence of warfarin is selectively degraded in the endoplasmic reticulum.
Author: Koide T; Tokunaga F; Wakabayashi S
Address: Department of Life Science, Faculty of Science, Himeji Institute of Technology, Hyogo, Japan.
Source: Pol J Pharmacol, 1996 Mar, 48:2, 203-7
Abstract: Warfarin is known to disrupt the microsomal vitamin K cycle, which results in a decrease of the plasma level of protein C, an anticoagulant factor, as well as some other vitamin K-dependent coagulation factors. We examined the effect of warfarin on secretion of recombinant protein C expressed in human kidney 293 or BHK cells. In transient expression, warfarin caused a two- to four-fold decrease in the quantity of protein C secreted, compared to findings with vitamin K-treated cells. Pulse-chase experiments using stable cells showed that, although recombinant protein C was secreted in the presence of vitamin K, the decrease in total amount of the radioactivity in the warfarin-treated cells suggested intracellular degradation. This degradation depended on the concentration of warfarin and was not inhibited by an endoplasmic reticulum (ER)-Golgi transport inhibitor or by lysosomotropic inhibitors. Thus, protein C synthesized in the presence of warfarin is selectively degraded and the degradation occurs in a pre-Golgi, nonlysosomal compartment. Among the protease inhibitors tested, N-acetyl-Leu-Leu-methioninal and N-acetyl-Leu-Leu-norleucinal blocked the degradation of protein C synthesized in the presence of warfarin and the protein C accumulated intracellularly, in a dose-dependent manner. Both inhibitors, however, did not disturb the secretion of protein C in the vitamin K-treated cells. Thus, a cysteine protease(s) appeared to be responsible for the degradation. These results suggest that protein C synthesized in the presence of warfarin was selectively degraded by a cysteine protease(g) in the ER through a "quality control" mechanism.
Language of Publication: English
Unique Identifier: 97266975

Return To Top
Return To Menu Position #60
Return To Menu Position #70

MeSH Heading (Major): Endoplasmic Reticulum|*ME; Protein C|*BI/GE/ME; Warfarin|*PD
MeSH Heading: Biodegradation; Carcinoma, Hepatocellular|ME; Cells, Cultured; DNA, Complementary|GE; Electrophoresis, Gel, Pulsed-Field; Enzyme-Linked Immunosorbent Assay; Gene Expression|DE; Human; In Vitro; Kidney|CY/ME; Precipitin Tests; Protease Inhibitors|PD; Protein Synthesis Inhibitors|PD; Recombinant Proteins|ME; Tumor Cells, Cultured; Vitamin K|PD

Publication Type: JOURNAL ARTICLE
ISSN: 1230-6002
Country of Publication: POLAND

Record 71 from database: MEDLINE
Return To Top
Return To Menu Position #60
Return To Menu Position #70

Title: Effect of metal ions on radical intensity and cytotoxic activity of ascorbate.
Author: Satoh K; Sakagami H
Address: Analysis Center, School of Pharmaceutical Sciences, Showa University, Tokyo, Japan.
Source: Anticancer Res, 1997 Mar, 17:2A, 1125-9
Abstract: Various metal ions were investigated for their ability to modify the radical intensity and cytotoxic activity of sodium ascorbate or ascorbic acid. The addition of metal ions, such as Cu+, Cu2+, Fe2+, Zn2+, Mn2+ and Fe3+, dose-dependently enhanced the ascorbyl radical intensity whereas Na+, K+, Ca2+ and Mg2+ were totally inactive. The enhancement of ascorbyl radical intensity by metal ions was tightly coupled with the accelerated degradation of ascorbate. Addition of either serum or albumin significantly reduced the stimulation effect of Cu2+, and almost completely eliminated that of Fe3+ and Zn2+. The noncytotoxic concentration of Cu2+ significantly enhanced the cytotoxicity of ascorbate against cultured human glioblastoma T98G cell line. The present data suggest the possible role of metal ions in the regulation of the biological activity of ascorbate.
Language of Publication: English
Unique Identifier: 97283326

Return To Top
Return To Menu Position #60
Return To Menu Position #70

MeSH Heading (Major): Ascorbic Acid|ME/*PD; Metals|*PD
MeSH Heading: Copper|PD; Dose-Response Relationship, Drug; Ferrous Compounds|PD; Free Radicals; Human; Hydrogen-Ion Concentration; Iron|PD; Zinc|PD

Publication Type: JOURNAL ARTICLE
ISSN: 0250-7005
Country of Publication: GREECE

Record 72 from database: MEDLINE
Return To Top
Return To Menu Position #70

Title: Formation of carbon dioxide from ascorbate in man.
Author: Kallner A; Hornig D; Pellikka R
Address
Source: Am J Clin Nutr, 1985 Mar, 41:3, 609-13
Abstract: Volunteers were given a steady intake of various individually different daily dosages of ascorbic acid. After 3 weeks 1-14C-labelled ascorbate was given together with various amounts of unlabelled ascorbic acid (90-1000 mg). Regardless of the total daily dose in cases where the carrier dose amounted to 180 mg or more, carbon dioxide was recovered from the breath. The amount recovered ranged from 1 to more than 30% of the given dose. The larger the amount of carrier the larger was the amount of label recovered as carbon dioxide. It is suggested that the formation of carbon dioxide is due to a presystemic effect as a result of microbiological or chemical degradation of ascorbate in the intestine.
Language of Publication: English
Unique Identifier: 85145626

Return To Top
Return To Menu Position #70

MeSH Heading (Major): Ascorbic Acid|*ME; Carbon Dioxide|*BI
MeSH Heading: Biotransformation; Breath Tests; Human; Kinetics; Male; Support, Non-U.S. Gov't

Publication Type: JOURNAL ARTICLE
ISSN: 0002-9165
Country of Publication: UNITED STATES

Record 73 from database: MEDLINE
Return To Top
Return To Menu Position #70

Title: Enhancement of radical intensity and cytotoxic activity of ascorbate by PSK and lignins.
Author: Satoh K; Sakagami H; Nakamura K
Address: Analysis Center, School of Pharmaceutical Sciences, Showa University, Tokyo, Japan.
Source: Anticancer Res, 1996 Sep, 16:5A, 2981-6
Abstract: ESR spectroscopy revealed that high molecular weight natural substances, such as protein-bound polysaccharide PSK, alkali-lignin and lignin sulfonate, significantly enhanced the ascorbyl radical intensity derived from sodium ascorbate or ascorbic acid in culture medium. Enhancement of the ascorbyl radical intensity was coupled with rapid degradation of ascorbate. These substances synergistically enhanced the ascorbate-induced cytotoxicity against human leukemic and glioblastoma cell lines. These data suggest the possible role of the ascorbyl radical in cytotoxicity induction.
Language of Publication: English
Unique Identifier: 97074989

Return To Top
Return To Menu Position #70

MeSH Heading (Major): Ascorbic Acid|CH/*ME; Lignin|*PD; Proteoglycans|*PD
MeSH Heading: Free Radicals|ME; Human; HL-60 Cells|DE; Tumor Cells, Cultured|DE

Publication Type: JOURNAL ARTICLE
ISSN: 0250-7005
Country of Publication: GREECE

Record 74 from database: MEDLINE
Return To Top
Return To Menu Position #70

Title: Expression and functional characterization of chimeras between human and bovine vitamin-K-dependent protein-S-defining modules important for the species specificity of the activated protein C cofactor activity.
Author: He X; Shen L; Dahlbäck B
Address: Department of Clinical Chemistry, Lund University, MalmÂo General Hospital, Sweden.
Source: Eur J Biochem, 1995 Jan, 227:1-2, 433-40
Abstract: Vitamin-K-dependent protein S is an anticoagulant plasma protein functioning as a cofactor to activated protein C (APC) in the degradation of factors Va and VIIIa. The APC-cofactor function of protein S is species specific, as human protein S potentiates the anticoagulant activity of human but not that of bovine APC, whereas bovine protein S is a cofactor to APC from both species. To elucidate which modules in protein S determine the species specificity, in vitro mutagenesis was used to construct six recombinant chimeric molecules between human and bovine protein S. Wild-type human and bovine protein S and the chimeras were expressed in 293 cells and the recombinant proteins purified by monoclonal antibody affinity chromatography. The recombinant proteins were found to be post-translationally modified, they bound C4b-binding protein and were functionally active as cofactors to APC. Chimeras having both the thrombin-sensitive region (TSR) and the first epidermal-growth-factor-(EGF)-like module of bovine origin expressed APC-cofactor activity similar to that of bovine protein S. Those chimeras, in which TSR or EGF1 derived from different species, manifested APC-cofactor activity similar to that of human protein S, i.e. they did not express cofactor activity to bovine APC. These data indicate that sequence differences in the TSR and EGF1 of human and bovine protein S cause the species specificity of the APC-cofactor activity. The data support the concept that these two modules of protein S interact with APC on the surface of negatively charged phospholipids.
Language of Publication: English
Unique Identifier: 95154323

Return To Top
Return To Menu Position #70

MeSH Heading (Major): Protein C|*ME; Protein S|*GE/ME
MeSH Heading: Amino Acid Sequence; Animal; Antibodies, Monoclonal; Base Sequence; Cattle; Cell Line; Chimeric Proteins|GE/ME; Human; Molecular Sequence Data; Oligodeoxyribonucleotides; Ribosomes|ME; Sequence Homology, Amino Acid; Species Specificity; Support, Non-U.S. Gov't

Publication Type: JOURNAL ARTICLE
ISSN: 0014-2956
Country of Publication: GERMANY

Record 75 from database: MEDLINE
Return To Top
Return To Menu Position #70

Title: Role of ascorbate in the activation of NF-kappaB by tumour necrosis factor-alpha in T-cells.
Author: Muñoz E; Blázquez MV; Ortiz C; Gomez Díaz C; Navas P
Address: Departamento de FisiologÆia e InmunologÆia, Facultad de Medicina, Universidad de CÆordoba, Avda. Menendez Pidal s/n, 14071 CÆordoba, Spain.
Source: Biochem J, 1997 Jul, 325 ( Pt 1):, 23-8
Abstract: The first product of ascorbate oxidation, the ascorbate free radical (AFR), acts in biological systems mainly as an oxidant, and through its role in the plasma membrane redox system exerts different effects on the cell. We have investigated the role of ascorbate, AFR and dehydroascorbate (DHA) in the activation of the NF-kappaB transcription factor in Jurkat T-cells stimulated by tumour necrosis factor-alpha (TNF-alpha). Here we show, by electrophoretic mobility shift assays, that ascorbate increases the binding of NF-kappaB to DNA in TNF-alpha-stimulated Jurkat cells. The ability of ascorbate to enhance cytoplasmic inhibitory IkBalpha protein degradation correlates completely with its capacity to induce NF-kappaB binding to DNA and to potentiate NF-kappaB-mediated transactivation of the HIV-1 long terminal repeat promoter in TNF-alpha-stimulated Jurkat cells but not in cells stimulated with PMA plus ionomycin. AFR behaves like ascorbate, while DHA and ascorbate phosphate do not affect TNF-alpha-mediated NF-kappaB activation. These results provide new evidence for a possible relationship between the activation of the electron-transport system at the plasma membrane by ascorbate or its free radical and redox-dependent gene transcription in T-cells.
Language of Publication: English
Unique Identifier: 97344237

Return To Top
Return To Menu Position #70

MeSH Heading (Major): Ascorbic Acid|*PD; DNA-Binding Proteins|*ME; NF-kappa B|AI/*ME; Tumor Necrosis Factor|*PD
MeSH Heading: Cell Division|DE; Dehydroascorbic Acid|PD; Human; Jurkat Cells; Kinetics; Luciferase|BI; Recombinant Fusion Proteins|BI; Support, Non-U.S. Gov't; T-Lymphocytes; Transfection

Publication Type: JOURNAL ARTICLE
ISSN: 0264-6021
Country of Publication: ENGLAND

Record 76 from database: MEDLINE
Return To Top
Return To Menu Position #70

Title: Effect of ascorbate oxidase on radical intensity and cytotoxic activity of ascorbate.
Author: Sakagami H; Satoh K
Address: Department of Biochemistry, School of Medicine, Showa University, Tokyo, Japan.
Source: Anticancer Res, 1997 Mar, 17:2A, 1163-6
Abstract: In order to test whether ascorbyl radical can directly induce apoptotic cell death, it was produced by the reaction of sodium L-ascorbate with L-ascorbate oxidase. Sodium L-ascorbate induced cytotoxicity against both human glioblastoma and promyelocytic leukemic cell lines. The addition of ascorbate oxidase significantly enhanced both degradation and radical generation of ascorbate, but completely eliminated its cytotoxic activity against both of these cells. These data demonstrate that the ascorbyl radical is not the sole determinant of apoptosis induction.
Language of Publication: English
Unique Identifier: 97283332

Return To Top
Return To Menu Position #70

MeSH Heading (Major): Antineoplastic Agents|*PD; Ascorbate Oxidase|*PH; Ascorbic Acid|ME/*PD
MeSH Heading: Free Radicals; Human

Publication Type: JOURNAL ARTICLE
ISSN: 0250-7005
Country of Publication: GREECE

Record 77 from database: MEDLINE
Return To Top
Return To Menu Position #70

Title: Cupric ion/ascorbate/hydrogen peroxide-induced DNA damage: DNA-bound copper ion primarily induces base modifications.
Author: Drouin R; Rodriguez H; Gao SW; Gebreyes Z; OConnor TR; Holmquist GP; Akman SA
Address: Division of Biology, Beckman Research Institute of the City of Hope, Duarte, CA, USA.
Source: Free Radic Biol Med, 1996, 21:3, 261-73
Abstract: The kinetics of frank DNA strand breaks and DNA base modifications produced by Cu(II)/ascorbate/H2O2 were simultaneously determined in purified human genomic DNA in vitro. Modified bases were determined by cleavage with Escherichia coli enzymes Nth protein (modified pyrimidines) and Fpg protein (modified purines). Single-stranded lesion frequency before (frank strand breaks) and after (modified bases) Nth or Fpg protein digestion was quantified by neutral glyoxal gel electrophoresis. Dialysis of EDTA-treated genomic DNA purified by standard proteinase K digestion/phenol extraction was necessary to remove low molecular weight species, probably transition metal ions and metal ion chelators, which supported frank strand breaks in the presence of ascorbate + H2O2 without supplemental copper ions. We then established a kinetic model of the DNA-damaging reactions caused by Cu(II) + ascorbate + H2O2. The principal new assumption in our model was that DNA base modifications were caused exclusively by DNA-bound Cu(I) and frank strand breaks by non-DNA-bound Cu(I). The model was simulated by computer using published rate constants. The computer simulation quantitatively predicted: (1) the rate of H2O2 degradation, which was measured using an H2O2-sensitive electrode, (2) the linearity of accumulation of DNA strand breaks and modified bases over the reaction period, (3) the rate of modified base accumulation, and (4) the dependence of modified base and frank strand production on initial Cu(II) concentration. The simulation significantly overestimated the rate of frank strand break accumulation, suggesting either that the ultimate oxidizing species that attacks the sugar-phosphate backbone is a less-reactive species than the hydroxyl radical used in the model and/or an unidentified hydroxyl radical-scavenging species was present in the reactions. Our experimental data are consistent with a model of copper ion-DNA interaction in which DNA-bound Cu(I) primarily mediates DNA base modifications and nonbound Cu(I) primarily mediates frank strand break production.
Language of Publication: English
Unique Identifier: 97008282

Return To Top
Return To Menu Position #70

MeSH Heading (Major): Ascorbic Acid|*PD; Copper|*ME/*PD; DNA|DE/*ME; DNA Damage|*; Hydrogen Peroxide|ME/*PD
MeSH Heading: Dialysis; Edetic Acid|PD; Electrophoresis, Agar Gel; Fibroblasts; Glyoxal; Human; Kinetics; Male; Support, Non-U.S. Gov't; Support, U.S. Gov't, P.H.S.

Publication Type: JOURNAL ARTICLE
ISSN: 0891-5849
Country of Publication: UNITED STATES

Record 78 from database: MEDLINE
Return To Top
Return To Menu Position #70

Title: A randomized, single-blind, placebo-controlled trial of the effects of 200 mg alpha-tocopherol on the oxidation resistance of atherogenic lipoproteins.
Author: Porkkala Sarataho EK; Nyyssönen MK; Kaikkonen JE; Poulsen HE; Hayn EM; Salonen RM; Salonen JT
Address: Research Institute of Public Health, University of Kuopio, Finland.
Source: Am J Clin Nutr, 1998 Nov, 68:5, 1034-41
Abstract: Supplementation with high doses of alpha-tocopherol has increased the oxidation resistance of LDL in many clinical trials. There have been only a few placebo-controlled trials in healthy persons of alpha-tocopherol doses usually contained in dietary supplements. We carried out a single-blind, placebo-controlled, randomized trial to examine the effect of 200 mg RRR-alpha-tocopheryl acetate/d on the oxidation resistance of atherogenic lipoproteins (VLDL+LDL including intermediate-density lipoproteins) in 40 smoking men. VLDL+LDL oxidation resistance was assessed as conjugated dienes after copper induction and hemin degradation after hydrogen peroxide induction. Also, the LDL total peroxyl-radical trapping antioxidant parameter (LDL TRAP) and plasma malondialdehyde were measured at baseline and after 2 mo of supplementation. Plasma RRR-alpha-tocopherol concentrations were measured at 2-h intervals for 12 h at baseline and after 2 mo of supplementation. Compared with placebo, 200-mg RRR-alpha-tocopheryl acetate supplementation elevated plasma and VLDL+LDL alpha-tocopherol concentrations, LDL TRAP, and oxidation resistance of VLDL+LDL. Plasma alpha-tocopherol increased by 88% (P < 0.0001), VLDL+LDL alpha-tocopherol increased by 90% (P < 0.0001), and LDL TRAP by 58% (P < 0.0001). The time to the start of oxidation (lag time) was prolonged by 34% when assessed with a copper-induced method and by 109% when assessed with a hemin + hydrogen peroxide-induced method; the time to maximal oxidation was prolonged by 21% (copper-induced method) in the vitamin E-supplemented group. Changes in plasma alpha-tocopherol, lipid-standardized alpha-tocopherol, and VLDL+LDL alpha-tocopherol correlated significantly with changes in LDL TRAP, lag time, and time to maximal oxidation. Differences in changes between groups in the area under the curve for plasma alpha-tocopherol were significant (P < 0.009). Our results suggest that 200 mg oral RRR-alpha-tocopheryl acetate/d had a clear effect on the in vitro oxidation of VLDL+LDL in smoking men.
Language of Publication: English
Unique Identifier: 99023405

Return To Top
Return To Menu Position #70

MeSH Heading (Major): Lipoproteins, LDL|BL/*ME; Lipoproteins, VLDL|BL/*ME; Vitamin E|AD/*BL/*PD
MeSH Heading: Ascorbic Acid|PD; Human; Male; Oxidation-Reduction|DE; Single-Blind Method; Smoking|ME; Support, Non-U.S. Gov't

Publication Type: CLINICAL TRIAL; JOURNAL ARTICLE; RANDOMIZED CONTROLLED TRIAL
ISSN: 0002-9165
Country of Publication: UNITED STATES

Record 79 from database: MEDLINE
Return To Top
Return To Menu Position #70
Return To Menu Position #80

Title: High density lipoprotein subclasses inhibit low density lipoprotein oxidation.
Author: Singh K; Chander R; Kapoor NK
Address: Division of Biochemistry, Central Drug Research Institute, Lucknow, India.
Source: Indian J Biochem Biophys, 1997 Jun, 34:3, 313-8
Abstract: It has been reported earlier that high density lipoprotein (HDL) is a scavenger of superoxide anions, hydroxyl radicals (OH-) and behaves like superoxide dismutase. In the present investigation, we have studied the effect of HDL subclasses: HDL2 and HDL3 on non enzymatically induced oxidation of low density lipoprotein (LDL) by Fe2+ and sodium ascorbate. Both HDL2 and HDL3 showed protection against the oxidative degradation of LDL-lipids, measured as thiobarbituric acid reactive substance, lipid hydroperoxide and conjugated diene. Oxidized LDL was more electronegative, as evidenced by the increase in relative electrophoretic mobility(REM) on agarose gel. HDL3 significantly protected LDL apoprotein as assessed by reversal of REM after oxidation. HDL2 and HDL3 significantly inhibited the generation of OH- in nonenzymic systems in vitro. However, HDL2 was more active against enzymic formation of OH- as compared to HDL3. Alpha-tocopherol could protect LDL lipids and apoprotein components by Fe2+ mediated oxidation but the effects were lower than HDL subclasses. Our findings suggest that HDL subclasses, the potent scavenger of oxygen derived free radicals, play an important role to prevent the oxidative modifications in LDL.
Language of Publication: English
Unique Identifier: 98086944

Return To Top
Return To Menu Position #70
Return To Menu Position #80

MeSH Heading (Major): Lipoproteins, HDL|ME/*PD; Lipoproteins, LDL|*ME
MeSH Heading: Antioxidants|PD; Ascorbic Acid|ME; Ferrous Compounds|ME; Free Radical Scavengers|ME; Human; Hydroxyl Radical|PD; Lipid Peroxidation|DE; Lipid Peroxides|AN; Oxidation-Reduction; Support, Non-U.S. Gov't

Publication Type: JOURNAL ARTICLE
ISSN: 0301-1208
Country of Publication: INDIA

Record 80 from database: MEDLINE
Return To Top
Return To Menu Position #70
Return To Menu Position #80

Title: Abnormally elevated serum transcobalamin II levels in patients with cerebral malaria.
Author: Areekul S; Churdchu K; Thanomsak W; Cheeramakara C; Wilairatana P; Charoenlarp P
Address: Department of Tropical Radioisotopes, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
Source: J Med Assoc Thai, 1994 Dec, 77:12, 657-62
Abstract: Transcobalamin II (TCII) levels have been reported to be elevated in patients with many clinical conditions including proliferative reticuloendothelial system. As reactive macrophage hyperplasia frequently occurs in patients with malaria, the objective of the present study was to determine TCII in patients with Plasmodium falciparum with cerebral symptoms. The studies were performed on 14 cerebral malaria patients as well as 60 normal subjects. The mean values of serum vitamin B12 and TCII levels were significantly higher in the patient group and 6 and 7 patients had serum vitamin B12 and TCII levels higher than the normal values. There was direct relationship between serum TCII levels and BUN or creatinine levels. These findings indicated that raised serum TCII level occurred only in patients with renal insufficiency. A decreased glomerular fiLtration rate reduced the amount of vitamin B12 and TCII-B12 that filtered through the glomeruli resulting in the reduced proximal tubular cells uptake and its degradation of TCII. This reduced lysosomal enzyme activity, therefore, prolongs the intravascular TCII survival and increased secretion of TCII into the circulation. Therefore, serum TCII levels were elevated in these cerebral malaria patients.
Language of Publication: English
Unique Identifier: 95279905

Return To Top
Return To Menu Position #70
Return To Menu Position #80

MeSH Heading (Major): Malaria, Cerebral|*BL; Transcobalamins|*AN
MeSH Heading: Adult; Blood Urea Nitrogen; Case-Control Studies; Child; Female; Human; Male; Vitamin B 12|BL

Publication Type: JOURNAL ARTICLE
ISSN: 0125-2208
Country of Publication: THAILAND

Record 81 from database: MEDLINE
Return To Top
Return To Menu Position #70
Return To Menu Position #80

Title: Protection of low density lipoprotein oxidation at chemical and cellular level by the antioxidant drug dipyridamole.
Author: Iuliano L; Colavita AR; Camastra C; Bello V; Quintarelli C; Alessandroni M; Piovella F; Violi F
Address: Institute of Clinical Medicine I, University La Sapienza, Rome, Italy.
Source: Br J Pharmacol, 1996 Dec, 119:7, 1438-46
Abstract: 1. The oxidative modification of low density lipoprotein (LDL) is thought to be an important factor in the initiation and development of atherosclerosis. Natural and synthetic antioxidants have been shown to protect LDL from oxidation and to inhibit atherosclerosis development in animals. Synthetic antioxidants are currently being tested, by they are not necessarily safe for human use. 2. We have previously reported that dipyridamole, currently used in clinical practice, is a potent scavenger of free radicals. Thus, we tested whether dipyridamole could affect LDL oxidation at chemical and cellular level. 3. Chemically induced LDL oxidation was made by Cu(II), Cu(II) plus hydrogen peroxide or peroxyl radicals generated by thermolysis of 2,2'-azo-bis(2-amidino propane). Dipyridamole, (1-10 microM), inhibited LDL oxidation as monitored by diene formation, evolution of hydroperoxides and thiobarbituric acid reactive substances, apoprotein modification and by the fluorescence of cis-parinaric acid. 4. The physiological relevance of the antioxidant activity was validated by experiments at the cellular level where dipyridamole inhibited endothelial cell-mediated LDL oxidation, their degradation by monocytes, and cytotoxicity. 5. In comparison with ascorbic acid, alpha-tocopherol and probucol, dipyridamole was the more efficient antioxidant with the following order of activity: dipyridamole > probucol > ascorbic acid > alpha-tocopherol. The present study shows that dipyridamole inhibits oxidation of LDL at pharmacologically relevant concentrations. The inhibition of LDL oxidation is unequivocally confirmed by use of three different methods of chemical oxidation, by several methods of oxidation monitoring, and the pharmacological relevance is demonstrated by the superiority of dipyridamole over the naturally occurring antioxidants, ascorbic acid and alpha-tocopherol and the synthetic antioxidant probucol.
Language of Publication: English
Unique Identifier: 97123306

Return To Top
Return To Menu Position #70
Return To Menu Position #80

MeSH Heading (Major): Antioxidants|*PD; Dipyridamole|*PD; Lipoproteins, LDL|*CH/*ME
MeSH Heading: Apolipoproteins B|CH/ME; B-Lymphocytes|DE/ME; Cells, Cultured; Copper|CH; Endothelium, Vascular|CY/ME; Human; Lipid Peroxidation|DE; Oxidation-Reduction; Spectrometry, Fluorescence; Spectrophotometry, Ultraviolet; Support, Non-U.S. Gov't; Thiobarbituric Acid Reactive Substances|ME

Publication Type: JOURNAL ARTICLE
ISSN: 0007-1188
Country of Publication: ENGLAND

Record 82 from database: MEDLINE
Return To Top
Return To Menu Position #70
Return To Menu Position #80

Title: Antioxidant and prooxidant properties of captopril and enalapril.
Author: Bartosz M; Kedziora J; Bartosz G
Address: Department of Physiology, Institute of Fundamental Sciences, Military Medical University, LÆodÆz, Poland.
Source: Free Radic Biol Med, 1997, 23:5, 729-35
Abstract: Captopril ([2S]-1-[3-mercapto-2-methyl-propionyl]-L-proline) was found to protect erythrocytes from hemolysis caused by 2,2'-azobis (2-amidinopropane) (AAPH) and hypochlorite, erythrocyte membranes from lipid peroxidation caused by tert-butyl hydroperoxide (tBOOH) and hypochlorite, erythrocyte membrane ATPases from inactivation caused by tBOOH and hemoglobin from oxidation caused by AAPH and tBOOH. In all these systems enalapril ([S]-1-[N-(1-[ethoxycarbonyl]-3-phenylpropyl)-L-alanyl]-L-proline) was not protective or even increased the damage, especially with hypochlorite, probably due to chloramine formation. Captopril but not enalapril inhibited ascorbate autoxidation caused by Cu2+, which indicates that captopril binds Cu2+. On the other hand, deoxyribose degradation caused by iron and copper ions and DNA damage by o-phenanthroline/Cu2+/H2O2/beta-mercaptoethanol was enhanced by both captopril and enalapril. The effect of captopril was usually higher, apparently due to the reducing properties of captopril, which could reduce metal ions enabling their participation in the Fenton reaction. These results indicate that only -SH-group-containing inhibitors of angiotensin-converting enzyme (ACE) may exhibit antioxidant properties, and that the antioxidant/prooxidant action of ACE inhibitors depends on the system studied in vitro.
Language of Publication: English
Unique Identifier: 97440990

Return To Top
Return To Menu Position #70
Return To Menu Position #80

MeSH Heading (Major): Angiotensin-Converting Enzyme Inhibitors|*PD; Antioxidants|*PD; Captopril|*PD; Enalapril|*PD
MeSH Heading: Adenosinetriphosphatase|ME; Ascorbic Acid|ME; Comparative Study; Deoxyribose; DNA Damage|DE; Erythrocyte Membrane|EN/ME; Hemolysis|DE; Human; Lipid Peroxidation|DE; Oxidation-Reduction

Publication Type: JOURNAL ARTICLE
ISSN: 0891-5849
Country of Publication: UNITED STATES

Record 83 from database: MEDLINE
Return To Top
Return To Menu Position #70
Return To Menu Position #80

Title: Improvement of some blood coagulation factors in cirrhotic patients treated with low doses of heparin.
Author: Cordova C; Musca A; Violi F; Alessandri C; Vezza E
Address
Source: Scand J Haematol, 1982 Sep, 29:3, 235-40
Abstract: Effects of subcutaneous calcium-heparin and vitamin K administration were studied in 30 cirrhotic patients showing low values of prothrombin time, antithrombin III, fibrinogen, platelet count, plasminogen, alpha 2-antiplasmin, raised levels of fibrin(ogen) degradation products and prolonged activated partial thromboplastin time. A group of 10 patients was first treated with K vitamin for 15 d; after vitamin K therapy interruption, a treatment with 5000 IU (8000 IU in 1 patient) every 12 h of subcutaneous calcium-heparin was started. In another group of 20 patients a treatment with 5000 IU (8000 IU in 2 patients) every 12 h of subcutaneous calcium-heparin was started immediately. The heparin administration in both groups had been performed for at least 2 weeks. No significant changes of blood coagulation picture were observed after vitamin K administration, while calcium-heparin treatment showed an increase in prothrombin time, fibrinogen, platelet count, plasminogen, alpha 2-antiplasmin, a decrease in fibrin(ogen) degradation products and a shortened activated partial thromboplastin time. There was no significant change in antithrombin III values.
Language of Publication: English
Unique Identifier: 83067178

Return To Top
Return To Menu Position #70
Return To Menu Position #80

MeSH Heading (Major): Blood Coagulation Factors|*AN; Heparin|AD/*TU; Liver Cirrhosis|BL/CO/*DT
MeSH Heading: Disseminated Intravascular Coagulation|ET; Dose-Response Relationship, Drug; Fibrinolysis|DE; Human; Male; Reticuloendothelial System|DE; Vitamin K|AD/TU

Publication Type: JOURNAL ARTICLE
ISSN: 0036-553X
Country of Publication: DENMARK

Record 84 from database: MEDLINE
Return To Top
Return To Menu Position #70
Return To Menu Position #80

Title: Oxidative structural modifications of low density lipoprotein in homozygous familial hypercholesterolemia.
Author: Napoli C; Postiglione A; Triggiani M; Corso G; Palumbo G; Carbone V; Ruocco A; Ambrosio G; Montefusco S; Malorni A; Condorelli M; Chiariello M
Address: Department of Medicine, Federico II, School of Medicine, University of Naples, Italy.
Source: Atherosclerosis, 1995 Dec, 118:2, 259-73
Abstract: Patients with homozygous familial hypercholesterolemia (FH), as a result of the increased levels and prolonged residence time of low density lipoprotein (LDL) in plasma, have a strong tendency toward accumulation of LDL-cholesterol in the arterial wall, causing premature atherosclerosis. This phenomenon may enhance per se the physiological degradation of both protein and lipid component of LDL, which be more susceptible to oxidative damage induced by oxygen radicals. It is well known that LDL may undergo oxidative modification before being taken up by macrophages which are then transformed into foam cells. It has been suggested that platelet-activating factor (PAF) may play an important role in atherogenesis and PAF catabolism is known to be mediated by serum acetylhydrolase, an enzyme that is normally associated with LDL. Thus, the present study was designed to investigate the structural properties of LDL, including acetylhydrolase activity, in homozygous FH as compared to normolipidemic subjects before and after xanthine/xanthine oxidase-mediated oxidation. We studied 8 homozygous FH patients matched with 8 normolipidemic volunteers. Lipids of LDL fraction were extracted and verified by thin layer chromatography (TLC) analysis. Fatty acids were methylated and injected into a gas chromatograph/mass spectrometer. Vitamin E in LDL was determined by high performance liquid chromatography (HPLC). As an index of susceptibility of LDL to oxidative modifications, the formation of lipid-conjugated dienes was continuously monitored at 234 nm. Lipid peroxidation was also evaluated from the amount of both lipid peroxides (LPO) and malonyldialdehyde (MDA) content. Apolipoprotein (apo) B-100 on LDL was carried on polyacrylamide and agarose gel electrophoresis. In the homozygous FH patients, the relative content of cholesteryl ester was slightly increased. Interestingly, the relative amount of arachidonic acid (20:4) was constantly increased in each lipid fraction in homozygous FH patients. The amount of vitamin E was not significantly different in the patient group from that in the control group. However, LDL from patients carried lower levels of vitamin E (nmol/mg LDL) than controls (2.7 +/- 0.4 vs. 2.9 +/- 0.3 P = NS). The results shows that lag time (min) was decreased (82 +/- 19 vs. 111 +/- 21; P < 0.05) and the maximal rate of diene production and total diene production was increased in homozygous FH patients. Mean levels of MDA were similar in both groups before oxidation, but levels after initiation of oxidation were significantly higher in the patient group. In contrast, mean levels of LPO were already higher in patients before oxidation (58 vs. 27 nmol/mg of protein; P < 0.05), and after initiation of oxidation were also significantly higher at each time points. When oxidized LDL was run on a polyacrylamide gel, an extensive apo B-100 fragmentation replaced by lower molecular mass fragments ranging from 45,000 to 205,000 m.wt., was observed only in LDL from homozygotes. Relative LDL agarose gel mobility shows that LDL from patients migrated higher than LDL of controls. Finally acetylhydrolase activity associated with LDL in patients was significantly reduced as compared to controls. Thus, in homozygous FH patients, LDL appeared more susceptible to oxidation in vitro; the indices for LDL oxidizability were all significantly different from those of controls. This phenomenon might be due to prolonged residence time of LDL in these patients, as suggested from high basal LPO levels and lower vitamin E levels carried by LDL. This hypothesis may explain together with the high content of arachidonic acid, the enhanced susceptibility of LDL from homozygous FH patients to oxidative damage.
Language of Publication: English
Unique Identifier: 96366143

Return To Top
Return To Menu Position #70
Return To Menu Position #80

MeSH Heading (Major): Hypercholesterolemia, Familial|*BL/GE; Lipoproteins, LDL|BL/*CH
MeSH Heading: Apolipoproteins B|BL; Cholesterol Esters|BL; Chromatography, Thin Layer; Fatty Acids|BL; Homozygote; Human; Lipid Peroxidation; Malondialdehyde|BL; Mass Fragmentography; Oxidation-Reduction; Reactive Oxygen Species; Receptors, Immunologic|ME; Support, Non-U.S. Gov't; Vitamin E|BL; Xanthine Oxidase|ME

Publication Type: JOURNAL ARTICLE
ISSN: 0021-9150
Country of Publication: IRELAND

Record 85 from database: MEDLINE
Return To Top
Return To Menu Position #80

Title: Antenatal drugs affecting vitamin K status of the fetus and the newborn.
Author: Astedt B
Address: Department of Obstetrics and Gynecology, University Hospital, Lund, Sweden.
Source: Semin Thromb Hemost, 1995, 21:4, 364-70
Abstract: Coumarin derivatives and anticonvulsants administered during pregnancy enter the fetal circulation, interfering with the action of vitamin K. Vitamin K plays a crucial part in the gamma-carboxylation of glutamic acid residues of the vitamin K-dependent coagulation factors prothrombin, FVII, FIX, and FX. Other vitamin K-dependent proteins in the coagulation cascade are protein C and protein S. Vitamin K-dependent bone proteins are osteocalcin and gamma-carboxyglutamate matrix protein. Administration of coumarol derivatives results in under carboxylation of the vitamin K-dependent proteins. Anticoagulation therapy with warfarin is followed by an increased risk of embryopathy, which has been shown to be greatest between gestational weeks 6 and 12. Administration of warfarin is also followed by an increased risk both of fetal intraventricular hemorrhage, and of cerebral microbleedings, which may result in microencephaly and mental retardation. Treatment with coumarol derivatives should therefore be avoided during pregnancy, even in pregnant women with artificial heart valves, and replaced by heparin. Hemorrhage in the newborn related to the use of anticonvulsant drugs during pregnancy occurs very early within the first 24 hours, probably due to increased degradation of vitamin K. Transplacental administration of vitamin K has been shown to prevent neonatal hemorrhage induced by maternal anticonvulsant therapy. Prophylactic administration of vitamin K, especially by intramuscular injection, has been reported to be associated with an increased risk of childhood cancer. However, subsequent extensive studies have yielded no evidence of any relationship between prophylactic vitamin K administration and the occurrence of childhood cancer.
Language of Publication: English
Unique Identifier: 96357539

Return To Top
Return To Menu Position #80

MeSH Heading (Major): Abnormalities, Drug-Induced|*ET; Anticoagulants|*AE/PK; Anticonvulsants|*AE/PK; Coumarins|*AE/PK; Fetal Diseases|*CI; Pregnancy Complications|*DT; Prenatal Exposure Delayed Effects|*; Vitamin K|AE/*PH/TU; Vitamin K Deficiency|*CI/EM/PC
MeSH Heading: Blood Coagulation Factors|ME; Child; Cohort Studies; Epilepsy|DT; Female; Great Britain|EP; Hemorrhage|CI; Human; Infant, Newborn; Maternal-Fetal Exchange; Neoplasms|CI/EP; Pregnancy; Protein Processing, Post-Translational; Support, Non-U.S. Gov't; Sweden|EP; Thrombosis|DT

Publication Type: JOURNAL ARTICLE; REVIEW; REVIEW, TUTORIAL
ISSN: 0094-6176
Country of Publication: UNITED STATES

Record 86 from database: MEDLINE
Return To Top
Return To Menu Position #80

Title: Oxidative stress on lens and cataract formation: role of light and oxygen.
Author: Varma SD; Chand D; Sharma YR; Kuck JF Jr; Richards RD
Address
Source: Curr Eye Res, 1984 Jan, 3:1, 35-57
Abstract: The mechanism of oxidative damage to the lens through intraocular photochemical generation of superoxide and its derivatization to other oxidants such as singlet oxygen, hydroxyl radical and hydrogen peroxide has been studied. Rat lenses when organ cultured aerobically in TC 199 containing additional amounts of riboflavin were damaged as demonstrated by an inhibition of the uptake of Rb 86 against a concentration gradient. The pump was not affected by light if the culture was conducted in the basal TC 199. However, light was observed to induce significant peroxidative degradation of the tissue lipids even in the basal medium, the degradation being indicated by the formation of malonaldehyde. Both the inhibition of the pump as well as the peroxidative degradation of the tissue lipids, were attenuated considerably by scavengers of superoxide and hydrogen peroxide. In addition, the lipid degradation was prevented by vitamins C and E. The results suggest that the photodynamic injury to the lens cation pump as well as to membrane lipids is incumbent upon an initial generation of superoxide and its derivatization to other oxidants. Thus, the ocular lens is susceptible to oxidative insult and physiological damage through photocatalytic generation of various oxygen radicals. Large concentrations of ascorbic acid in the aqueous humor seems to be able to provide significant protection against such an insult. Thus, this may be one of the functions of high concentration of ascorbic acid in the aqueous humor. The implication of oxidative stress has also been examined in the genesis of cataracts in vivo. Treatment with vitamin E of the Emory mouse led to a decrease in the rate of cataract progression suggesting that at least in some instances an oxidative stress could participate in the formation of cataracts. Oxygen radicals may inflict damage at multifarious biochemical sites. Human lens lipids were also shown to have an absorption maxima at 239 nm indicating their susceptibility to oxidative degradation. In addition the lipid extract has fluorescence similar to that of lipofuscins. The levels of MDA were higher in the brunescent cataracts as compared to that in the nonbrunescent cataracts. The implications of oxidative stress towards the genesis of cataracts in humans is being explored further.
Language of Publication: English
Unique Identifier: 84083417

Return To Top
Return To Menu Position #80

MeSH Heading (Major): Cataract|*ET/PC; Lens, Crystalline|DE/ME/*RE; Oxygen|*PD
MeSH Heading: Animal; Comparative Study; Dogs; Free Radicals; Guinea Pigs; Human; In Vitro; Light|AE; Mice; Photochemistry; Rabbits; Rats; Support, Non-U.S. Gov't; Support, U.S. Gov't, P.H.S.; Vitamin E|PD

Publication Type: JOURNAL ARTICLE; REVIEW
ISSN: 0271-3683
Country of Publication: ENGLAND

Record 87 from database: MEDLINE
Return To Top
Return To Menu Position #80

Title: Protein modification by the degradation products of ascorbate: formation of a novel pyrrole from the Maillard reaction of L-threose with proteins.
Author: Nagaraj RH; Monnier VM
Address: Department of Ophthalmology, Case Western Reserve University, Cleveland, OH, USA.
Source: Biochim Biophys Acta, 1995 Nov, 1253:1, 75-84
Abstract: Ascorbate (vitamin C) degradation products can undergo non-enzymatic glycation (Maillard reaction) with proteins to form highly crosslinked structures with brown pigmentation and characteristic fluorescence. Proteins in the body, especially the long-lived proteins develop similar changes during aging and diabetes. Several studies have shown excessive degradation of ascorbate in plasma in diabetes, and in ocular lens during aging and cataract formation. Recent studies have suggested that ascorbate degradation products-mediated glycation plays a role in lens pigmentation and cataract formation. However, the precise chemical nature of ascorbate-specific advanced glycation end-products are not known. Here, we report the purification and characterization of a glycation end-product derived from one of the major degradation products of ascorbate, L-threose. This compound was characterized to be 2-acetamido-6-(3-(1,2-dihydroxyethyl)-2-formyl-4-hydroxymethyl-1- pyrrolyl)hexanoic acid (formyl threosyl pyrrole or FTP) formed by the condensation of epsilon-amino group of lysine with two molecules of threose. Formation of FTP occurred rapidly in the incubation of threose and lysine and reached plateau level within a day. We have developed a sensitive assay for its quantification in proteins based on enzyme digestion followed by HPLC. Ribonuclease A and human lens crystallins incubated with L-threose showed time- and sugar concentration-dependent increases in FTP, reaching 8.2 and 2.48 nmol per mg protein, respectively after one week of incubation. Human plasma proteins showed a peak with identical retention time as that of purified FTP under two different HPLC conditions. FTP may be used as a sensitive marker to assess ascorbate-mediated protein glycation and modifications in aging and diabetes.
Language of Publication: English
Unique Identifier: 96085093

Return To Top
Return To Menu Position #80

MeSH Heading (Major): Glycosylation End Products, Advanced|*CH; Hexanoic Acids|*CH; Maillard Reaction|*; Proteins|*CH; Pyrroles|*CH; Tetroses|*CH
MeSH Heading: Arginine|AA/CH; Blood Proteins|CH; Chromatography, High Pressure Liquid; Collagen|CH; Cross-Linking Reagents|CH; Crystallins|ME; Diabetes Mellitus|BL; Fluorescence; Human; Lysine|AA/CH; Models, Chemical; Nuclear Magnetic Resonance; Ribonuclease, Pancreatic|CH; Spectrophotometry; Spectrum Analysis, Mass; Support, Non-U.S. Gov't; Support, U.S. Gov't, P.H.S.

Publication Type: JOURNAL ARTICLE
ISSN: 0006-3002
Country of Publication: NETHERLANDS

Record 88 from database: MEDLINE
Return To Top
Return To Menu Position #80

Title: Protein C.
Author: Esmon CT
Address
Source: Prog Hemost Thromb, 1984, 7:, 25-54
Abstract: The protein C anticoagulant pathway provides many new insights into control mechanisms for regulating coagulation. The observation that protein C deficiency is associated with thrombotic tendencies in the heterozygote (106-109) and early, lethal thrombosis in the homozygote (110, 111) points to the importance of the system as a major regulatory pathway. The complexity of the system has only recently begun to emerge. Thrombin activation of protein C at the endothelial cell surface requires not only the synthesis of thrombomodulin but the coupling of the receptor to a protein C binding site. It is reasonable to assume that an inherited or acquired deficiency in thrombomodulin might lead to thrombotic tendencies. This aspect of the system may explain, in part, the association between vascular disease and thrombosis. Once activated, protein C has an almost total dependence on protein S to express anticoagulant activity. (98) This suggests that deficiencies of protein S may also be associated with thrombotic tendencies. Protein S offers an additional intriguing property. Protein S, a regulatory protein of the coagulation system, is found both free and associated with C4BP, a regulatory protein of the complement system. The high affinity, very stable interaction between these components (85) suggests that the interaction is likely to be involved in regulation. (89) The importance of the interaction remains to be demonstrated, but clearly this is a potential direct link between major control proteins of the coagulation and complement system. Clinical studies suggest that protein C and/or thrombomodulin might be effective therapeutically. Certainly, protein C supplementation during the onset of oral anticoagulant therapy would be expected to circumvent the transient rapid decrease in protein C levels that may influence the early effectiveness of oral anticoagulants. (119) In addition to the systems clinical importance, protein C, its activation, and its function offer a variety of intriguing biochemical problems. For instance, how does thrombomodulin alter the specificity of thrombin? What is the protein C binding site on the cell surface, and what role does Factor Va or its degradation products play in the formation and regulation of this site? How does protein S facilitate activated protein C anticoagulant activity and what roles do membrane surfaces play in this system? What role does beta-hydroxyaspartic acid play in protein C activation and function? How does activated protein C influence fibrinolytic activity? The answers to these questions will undoubtedly add to our understanding of the fundamental mechanisms involved in regulating blood coagulation.(ABSTRACT TRUNCATED AT 400 WORDS)
Language of Publication: English
Unique Identifier: 85167122

Return To Top
Return To Menu Position #80

MeSH Heading (Major): Blood Coagulation Factors|*PH; Glycoproteins|DF/ME/*PH
MeSH Heading: Amino Acid Sequence; Animal; Anticoagulants|PD; Antithrombin III|PH; Blood Coagulation; Blood Proteins|ME; Blood Vessels|PH; Calcium|PH; Carrier Proteins|ME; Cattle; Dogs; Endothelium|PH; Factor V|ME; Factor VIII|ME; Factor X|ME; Fibrinolysis; Human; Models, Biological; Plasminogen Activators|PH; Protein Precursors|ME; Receptors, Cell Surface|ME/PH; Substrate Specificity; Support, Non-U.S. Gov't; Support, U.S. Gov't, P.H.S.; Thrombin|PH; Vitamin K|PH; 1-Carboxyglutamic Acid|PH

Publication Type: JOURNAL ARTICLE; REVIEW
ISSN: 0362-6350
Country of Publication: UNITED STATES

Record 89 from database: MEDLINE
Return To Top
Return To Menu Position #80

Title: Inactivation of human coagulation factor V by activated protein C.
Author: Suzuki K; Stenflo J; Dahlbäck B; Teodorsson B
Address
Source: J Biol Chem, 1983 Feb, 258:3, 1914-20
Abstract: Thrombin-activated vitamin K-dependent protein C purified from human plasma has a potent anticoagulant effect on human plasma, whereas its bovine counterpart has a very weak anticoagulant effect on human plasma. This species difference was found to be partly due to a more rapid degradation of human factor Va by human than by bovine activated protein C. In the presence of phospholipid, activated human protein C cleaves several peptide bonds in fragment D (heavy chain of factor Va), whereas in fragment F1F2 (light chain of factor Va) there appears to be only one peptide bond that is slowly cleaved. The degradation of fragment D is accompanied by a parallel loss of factor V activity. With the blood coagulation factor Xa bound to factor Va, fragment D is protected from degradation by activated protein C, and factor Va remains active. Fragment D isolated from factor Va was exposed to activated protein C in the presence of phospholipid and was found not to be degraded. This observation suggests that fragment D of factor V is bound to phospholipid via fragment F1F2.
Language of Publication: English
Unique Identifier: 83108998

Return To Top
Return To Menu Position #80

MeSH Heading (Major): Blood Coagulation Factors|*PH; Factor V|*PH; Glycoproteins|*PH
MeSH Heading: Amino Acids|AN; Enzyme Activation; Factor X|PH; Human; Kinetics; Molecular Weight; Support, Non-U.S. Gov't; Thrombin|PH

Publication Type: JOURNAL ARTICLE
ISSN: 0021-9258
Country of Publication: UNITED STATES

Record 90 from database: MEDLINE
Return To Top
Return To Menu Position #80
Return To Menu Position #90

Title: Bone mineral density measured by dual-energy x-ray absorptiometry and novel markers of bone formation and resorption in patients on antiepileptic drugs.
Author: Välimäki MJ; Tiihonen M; Laitinen K; Tähtelä R; Kärkkäinen M; Lamberg Allardt C; Mäkelä P; Tunninen R
Address: Third Department of Medicine, University of Helsinki, Finland.
Source: J Bone Miner Res, 1994 May, 9:5, 631-7
Abstract: In patients on antiepileptic drugs, bone loss has been mainly demonstrated at radial sites using old technology and has been ascribed to drug-induced vitamin D deficiency rather than to any direct effects of the treatment on bone cells. We examined 38 epileptic patients (24 women and 14 men) aged 20-49 years who were using either carbamazepine or phenytoin or both. Bone mineral density (BMD) at the lumbar spine and three femoral sites was measured by dual-energy x-ray absorptiometry (DXA) and serum and urine markers of bone and mineral metabolism were determined. The latter included the C-terminal extension peptide of type I procollagen (PICP), a putative serum marker of bone formation, and the cross-linked carboxyl-terminal telopeptide of human type I collagen (ICTP), a novel serum marker of bone matrix degradation. In female patients on phenytoin, weight- and height-adjusted BMD was reduced at the femoral neck and the Ward's triangle (p < 0.05) but was at the control level in the other patient groups at all four measurement sites. Compared with controls, the serum concentrations of 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D were reduced by 26% (p < 0.01) and by 27% (p < 0.001) in female patients. These changes were independent of the therapy used. They were not present in male patients. For both genders the serum levels of vitamin D binding protein were normal. Both female and male patients had hypocalcemia, but women only showed hypocalciuria.(ABSTRACT TRUNCATED AT 250 WORDS)
Language of Publication: English
Unique Identifier: 94330396

Return To Top
Return To Menu Position #80
Return To Menu Position #90

MeSH Heading (Major): Bone Density|*DE/PH; Bone Development|*DE; Bone Resorption|*CI; Carbamazepine|*AE/TU; Epilepsy|*DT; Phenytoin|*AE/TU
MeSH Heading: Adult; Alkaline Phosphatase|BL; Calcium|BL/UR; Collagen|BL; Densitometry, X-Ray; Female; Femur; Human; Hydroxycholecalciferols|BL; Lumbar Vertebrae; Male; Middle Age; Osteocalcin|BL; Parathyroid Hormones|BL; Peptide Fragments|BL; Peptides|BL; Procollagen|BL; Support, Non-U.S. Gov't

Publication Type: JOURNAL ARTICLE
ISSN: 0884-0431
Country of Publication: UNITED STATES

Record 91 from database: MEDLINE
Return To Top
Return To Menu Position #80
Return To Menu Position #90

Title: Different agonist- and antagonist-induced conformational changes in retinoic acid receptors analyzed by protease mapping.
Author: Keidel S; LeMotte P; Apfel C
Address: Department of Dermatology, F. Hoffmann-La Roche Ltd., Basel, Switzerland.
Source: Mol Cell Biol, 1994 Jan, 14:1, 287-98
Abstract: The pleiotropic effects of retinoic acid on cell differentiation and proliferation are mediated by two subfamilies of nuclear receptors, the retinoic acid receptors (RARs) and the retinoid X receptors (RXRs). Recently the synthetic retinoid Ro 41-5253 was identified as a selective RAR alpha antagonist. As demonstrated by gel retardation assays, Ro 41-5253 and two related new RAR alpha antagonists do not influence RAR alpha/RXR alpha heterodimerization and DNA binding. In a limited trypsin digestion assay, complexation of RAR alpha with retinoic acid or several other agonistic retinoids altered the degradation of the receptor such that a 30-kDa proteolytic fragment became resistant to proteolysis. This suggests a ligand-induced conformational change, which may be necessary for the interaction of the DNA-bound RAR alpha/RXR alpha heterodimer with other transcription factors. Our results demonstrate that antagonists compete with agonists for binding to RAR alpha and may induce a different structural alteration, suggested by the tryptic resistance of a shorter 25-kDa protein fragment in the digestion assay. This RAR alpha conformation seems to allow RAR alpha/RXR alpha binding to DNA but not the subsequent transactivation of target genes. Protease mapping with C-terminally truncated receptors revealed that the proposed conformational changes mainly occur in the DE regions of RAR alpha. Complexation of RAR beta, RAR gamma, and RXR alpha, as well as the vitamin D3 receptor, with their natural ligands resulted in a similar resistance of fragments to proteolytic digestion. This could mean that ligand-induced conformational changes are a general feature in the hormonal activation of vitamin D3 and retinoid receptors.
Language of Publication: English
Unique Identifier: 94088525

Return To Top
Return To Menu Position #80
Return To Menu Position #90

MeSH Heading (Major): Receptors, Cytoplasmic and Nuclear|*CH/DE/GE; Receptors, Retinoic Acid|*CH/DE/GE
MeSH Heading: Animal; Benzoates|PD; Chromans|PD; Cloning, Molecular; Human; Mice; Models, Biological; Naphthalenes|PD; Peptide Mapping; Peptide Peptidohydrolases; Protein Conformation|DE; Retinoids|PD; Sequence Deletion; Tretinoin|PD

Publication Type: JOURNAL ARTICLE
ISSN: 0270-7306
Country of Publication: UNITED STATES

Record 92 from database: MEDLINE
Return To Top
Return To Menu Position #90

Title: Protein C, an antithrombotic protein, is reduced in hospitalized patients with intravascular coagulation.
Author: Griffin JH; Mosher DF; Zimmerman TS; Kleiss AJ
Address
Source: Blood, 1982 Jul, 60:1, 261-4
Abstract: Activated protein C is a potent anticoagulant and profibrinolytic enzyme that can be derived from the vitamin-K-dependent serine protease zymogen, protein C, by the action of thrombin. Protein C antigen concentration was determined in plasmas from normals (n = 40) and from 38 patients with intravascular coagulation as evidenced by positive FDP (greater than micrograms/ml). Plasma protein C was 4 micrograms/ml in normals and was significantly depressed (less than 2 SD below the mean of normals) in 19 of the 38 patients. Of 15 patients with suspected intravascular coagulation but normal FDP, protein C was decreased in 5 individuals; 3 of these 5 patients had liver disease. Based on these results, we suggest that extensive activation of the coagulation system in vivo causes a significant consumption of protein C, presumably due to its activation by thrombin and subsequent clearance.
Language of Publication: English
Unique Identifier: 82207094

Return To Top
Return To Menu Position #90

MeSH Heading (Major): Blood Coagulation|*; Disseminated Intravascular Coagulation|*BL/CO; Glycoproteins|AN/IM/*ME
MeSH Heading: Antigens|AN; Fibrin Fibrinogen Degradation Products|AN; Human; Liver Diseases|BL/CO; Support, Non-U.S. Gov't; Support, U.S. Gov't, P.H.S.

Publication Type: JOURNAL ARTICLE
ISSN: 0006-4971
Country of Publication: UNITED STATES

Record 93 from database: MEDLINE
Return To Top
Return To Menu Position #90

Title: Reconstruction of parodontal tissue with chitosan.
Author: Muzzarelli R; Biagini G; Pugnaloni A; Filippini O; Baldassarre V; Castaldini C; Rizzoli C
Address: Faculty of Medicine, University of Ancona, Italy.
Source: Biomaterials, 1989 Nov, 10:9, 598-603
Abstract: Chitosan ascorbate, obtained by mixing chitosan with ascorbic acid and sodium ascorbate, was produced in a gel form suitable for the treatment of periodontitis according to current dental surgery. While chitosan ascorbate underwent degradation in vitro, especially in the presence of atmospheric oxygen and at pH 6.0, the protection from oxygen offered by the surgical cements and the physiological pH value permitted chitosan ascorbate to play an important biological role in vivo, where it kept a honeycomb structure, as indicated by SEM on biopsies taken on 10 patients. The proliferation and organization of the cells were thus favoured with a subsequent enhanced capability of reconstructing a histoarchitectural tissue. Chitosan was progressively reabsorbed by the host, with very satisfactory clinical recoveries of the 52 defects treated, for which tooth mobility and pocket depths were significantly reduced.
Language of Publication: English
Unique Identifier: 90123009

Return To Top
Return To Menu Position #90

MeSH Heading (Major): Biocompatible Materials|*; Chitin|*AA; Periodontitis|*SU; Periodontium|*SU/UL
MeSH Heading: Adult; Ascorbic Acid; Female; Human; Male; Microscopy, Electron; Microscopy, Electron, Scanning; Middle Age; Support, Non-U.S. Gov't

Publication Type: JOURNAL ARTICLE
ISSN: 0142-9612
Country of Publication: ENGLAND

Record 94 from database: MEDLINE
Return To Top
Return To Menu Position #90

Title: Effect of intravenous calcitriol on secondary hyperparathyroidism in chronic hemodialysis patients.
Author: Liou HH; Chiang SS; Tsai SC; Chang CC; Wu SC; Shieh SD; Huang TP
Address: Department of Medicine, Veterans General Hospital-Taipei, Taiwan, R.O.C.
Source: Chung Hua I Hsueh Tsa Chih (Taipei), 1994 Jun, 53:6, 319-24
Abstract: BACKGROUND. It has become evident that calcitriol can suppress parathyroid hormone (PTH) secretion by direct genomic actions. Intravenous calcitriol that bypasses gastrointestinal degradation might cause less degree of hypercalcemia and greater suppressive effect on PTH secretion. We investigated this PTH-suppressive effect of intravenous calcitriol in hemodialysis patients with secondary hyperparathyroidism. METHODS. Calcitriol was administered at the end of each dialysis session three times a week in 20 uremic patients, for 12 weeks. RESULTS. The mean dosage of calcitriol was 2.72 +/- 0.21 microgram per dialysis session. Serum intact PTH and C-PTH decreased (P < 0.05) after 6 weeks of treatment, while serum alkaline phosphatase (Alk-P) decreased 3 weeks later than PTH did. The individual maximal reduction of intact PTH, C-PTH and Alk-P were 77.80%, 67.36% and 45.98%. This PTH-suppression was dose-dependent. Despite the significant reduction of intact PTH by 58.17% after 6 weeks of treatment, no significant increase of serum calcium was found. An increase in serum calcium is not essential for this PTH-suppressive effect of calcitriol. Our observations thus provide another evidence to support the direct inhibitory effect of calcitriol on PTH secretion. Serum calcium, phosphorus, magnesium, albumin and osteocalcin levels did not change significantly. No side effect was found during treatment. CONCLUSIONS. Intravenous calcitriol is effective and safe in treating hemodialysis patients with secondary hyperparathyroidism. This treatment is more important in patients who are intolerant to oral vitamin D supply and who are candidates for surgical parathyroidectomy.
Language of Publication: English
Unique Identifier: 94373662

Return To Top
Return To Menu Position #90

MeSH Heading (Major): Calcitriol|AD/*TU; Hemodialysis|*; Hyperparathyroidism, Secondary|BL/*DT
MeSH Heading: Adult; Alkaline Phosphatase|BL; Female; Human; Infusions, Intravenous; Male; Middle Age; Parathyroid Hormones|BL

Publication Type: JOURNAL ARTICLE
ISSN: 0578-1337
Country of Publication: TAIWAN

Record 95 from database: MEDLINE
Return To Top
Return To Menu Position #90

Title: Biochemical markers for assessing skeletal growth.
Author: Robins SP
Address: Biochemical Sciences Division, Rowett Research Institute, Bucksburn, Aberdeen, Scotland, UK.
Source: Eur J Clin Nutr, 1994 Feb, 48 Suppl 1:, S199-209
Abstract: Many of the biochemical markers for assessing skeletal turnover are based on the unique metabolism of fibrillar collagens. Intracellular modifications lead to the formation of hydroxyproline and hydroxylysine glycosides, both of which have been used as markers of collagen degradation. However, hydroxyproline is metabolised extensively in the liver and both components may be derived from several different tissue sources. The pyridinium crosslinks of collagen have been shown to provide more specific and sensitive markers of collagen degradation, since these compounds are only present in the mature, insoluble fibrils. In addition, pyridinium crosslinks are unaffected by diet and are not metabolised in the body. Following development of HPLC methods for the quantification of urinary crosslinks, these techniques have been validated as indices of bone resorption in studies of a wide range of metabolic bone diseases. Subsequently, the proportion of free crosslinks in urine was shown to be relatively consistent in different individuals, allowing development of a simple, direct immunoassay. The excretion of crosslinks in children was related to growth velocity and, in studies of malnourished children, the values before treatment were related to the child's growth response. For measuring bone formation, the serum concentrations of the C-terminal propeptide of procollagen type I (PICP) appear to reflect the activity of the osteoblasts, but additional information on physiological variations is necessary. The major non-collagenous components of bone in serum, osteocalcin or bone Gla protein, has long been used as a marker of bone formation, but there are a number of factors that complicate interpretation of the results. These include variations in the immunochemical reactivity, the possible presence of degradation fragments in serum and the dependence of vitamin K status for adequate enzymatic carboxylation. Nevertheless, assays for intact osteocalcin have been shown to be related to growth velocity in children. There are few suitable serum or urinary indices for cartilage metabolism and development of more specific markers, particularly for growth plate cartilage, are required to distinguish between linear growth and bone remodelling. Assessments of skeletal metabolism should, wherever possible, include a combination of different markers so that the balance between formative and resorptive events can be adequately evaluated.
Language of Publication: English
Unique Identifier: 94273652

Return To Top
Return To Menu Position #90

MeSH Heading (Major): Bone and Bones|*ME; Bone Development|*; Bone Resorption|*ME; Cartilage, Articular|*ME; Child Nutrition|*
MeSH Heading: Adolescence; Biological Markers|AN; Child; Child, Preschool; Chromatography, High Pressure Liquid; Collagen|BI; Human; Osteocalcin|BI; Procollagen|BI; Support, Non-U.S. Gov't

Publication Type: JOURNAL ARTICLE; REVIEW; REVIEW, TUTORIAL
ISSN: 0954-3007
Country of Publication: ENGLAND

Record 96 from database: MEDLINE
Return To Top
Return To Menu Position #90

Title: 17-beta estradiol protects neurons from oxidative stress-induced cell death in vitro.
Author: Behl C; Widmann M; Trapp T; Holsboer F
Address: Max Planck Institute of Psychiatry, Department of Neuroendocrinology, Munich, Germany.
Source: Biochem Biophys Res Commun, 1995 Nov, 216:2, 473-82
Abstract: The potential antioxidant activity of 17-beta estradiol and other steroid hormones in neuronal cells was investigated by studying oxidative stress-induced cell death caused by the neurotoxins amyloid beta protein, hydrogen peroxide and glutamate in the clonal mouse hippocampal cell line HT22. Preincubation of the cells with 10(-5) M 17-beta estradiol prior to addition of the neurotoxins prevented oxidative stress-induced cell damage and ultimately cell death, as detected with cell viability (MTT) and cell lysis (trypan blue exclusion/cell counting; propidium iodide staining) assays. At the DNA level, 17-beta estradiol blocked the DNA degradation caused by glutamate. Other steroid hormones, such as progesterone, aldosterone, corticosterone and the steroid precursor cholesterol, did not protect the cells. The neuronal protection afforded by 17-beta estradiol was estrogen receptor-independent. These data demonstrate a potent neuroprotective activity of the antioxidant 17-beta estradiol, which may have implications for the prevention and treatment of Alzheimer's disease.
Language of Publication: English
Unique Identifier: 96063633

Return To Top
Return To Menu Position #90

MeSH Heading (Major): Amyloid beta-Protein|*TO; Antioxidants|*PD; Cell Death|*DE; Estradiol|*PD; Neurons|CY/*DE/PH; Neurotoxins|*TO; Oxidative Stress|*; Receptors, Estrogen|BI/DE/*PH
MeSH Heading: beta-Galactosidase|BI; Aldosterone|PD; Alzheimer Disease|PC/TH; Analysis of Variance; Animal; Cell Line; Cell Survival|DE; Cholesterol|PD; Comparative Study; Corticosterone|PD; Glutamic Acid|TO; Hippocampus; Human; Hydrogen Peroxide|TO; Luciferase|BI; Mice; Progesterone|PD; Recombinant Fusion Proteins|BI/DE/ME; Transfection; Vitamin E|PD

Publication Type: JOURNAL ARTICLE
ISSN: 0006-291X
Country of Publication: UNITED STATES

Record 97 from database: MEDLINE
Return To Top
Return To Menu Position #90

Title: Investigation of ascorbate-Cu (II) induced cleavage of DNA by scanning tunneling microscopy.
Author: Zareie MH; Erdem G; Oner C; Oner R; Ogüs A; Piskin E
Address: Chemical Engineering Department, Hacettepe University, Beytepe, Ankara, Turkey.
Source: Int J Biol Macromol, 1996 Jul, 19:1, 69-73
Abstract: Scanning Tunneling Microscopy (STM) was used for the investigation of oxidative DNA damage. A PCR amplified fragment of human beta-globin gene was used as a model for time dependent cleavage reaction by ascorbate and copper. Cleavage reactions were carried out in a medium containing 0.5 microgram/20 microliters DNA, 20 nM Tris-HC1 pH, 7.8 and ascorbate-Cu (II) in the final concentrations of 1 mM and 30 microM, respectively. The mixtures were incubated at 37 degrees C for 5, 15 and 30 min. For STM studies, 3 pg/5 microliters DNA samples were deposited on the gold coated mica and dried in a water flow vacuum drier. The STM was operated in air at atmospheric pressure with a tip-to-substrate bias of 100 mV and tunneling currents of < 10 pA. Etched tips of Pt/Ir wires were used in a constant current mode. The degradated DNA structure can be distinguished from the intact DNA and the sizes of the degradation products can be identified in the STM micrographs. The size of fragments decreased from approximately 3000 A to 34 A in ascorbate-Cu (II) medium, after 30 min of incubation.
Language of Publication: English
Unique Identifier: 96376873

Return To Top
Return To Menu Position #90

MeSH Heading (Major): Ascorbic Acid|*PD; Copper|*PD; DNA Damage|*
MeSH Heading: Globin|GE; Human; Microscopy, Scanning Tunneling; Oxidative Stress; Polymerase Chain Reaction; Support, Non-U.S. Gov't; Time Factors

Publication Type: JOURNAL ARTICLE
ISSN: 0141-8130
Country of Publication: ENGLAND

Record 98 from database: MEDLINE
Return To Top
Return To Menu Position #90

Title: Determination of serum retinol by reversed-phase high-performance liquid chromatography.
Author: Siddiqui FQ; Malik F; Fazli FR
Address: Drugs Control and Traditional Medicines Division, National Institute of Health, Islamabad, Pakistan.
Source: J Chromatogr B Biomed Appl, 1995 Apr, 666:2, 342-6
Abstract: A rapid, sensitive and specific high-performance liquid chromatographic method was developed for the determination of serum levels of retinol in humans. A direct serum injection technique after deproteinisation was used to avoid lengthy pretreatment steps which can result in degradation of retinol during analysis. The column used was CLC-ODS, the mobile phase was acetonitrile-water and detection wavelength was 328 nm. Deterioration in column performance was not observed even after injection of 300 samples. The lower detection limit was 10 micrograms/l. On analyzing a serum pool six times, a C.V. of 0.7% was obtained. The method is quantitative, reproducible, rapid and highly accurate for routine analysis.
Language of Publication: English
Unique Identifier: 95360221

Return To Top
Return To Menu Position #90

MeSH Heading (Major): Chromatography, High Pressure Liquid|*MT; Vitamin A|*BL
MeSH Heading: Child, Preschool; Female; Human; Infant; Male; Reproducibility of Results

Publication Type: JOURNAL ARTICLE
ISSN: 0378-4347
Country of Publication: NETHERLANDS

Record 99 from database: MEDLINE
Return To Top
Return To Menu Position #90

Title: The stability of retinol, alpha-tocopherol, trans-lycopene, and trans-beta-carotene in liquid-frozen and lyophilized serum.
Author: Brown Thomas J; Duewer DL; Kline MC; Sharpless KE
Address: Analytical Chemistry Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA. jeanice.brownthomas@nist.gov
Source: Clin Chim Acta, 1998 Aug, 276:1, 75-87
Abstract: The concentrations of retinol, alpha-tocopherol, and trans-beta-carotene in lyophilized serum stored at -25 degrees C and -80 degrees C have been monitored for 10 years. There was no evidence of degradation of any of these compounds over the 10-year period. Retinol, alpha-tocopherol, and trans-beta-carotene were less stable at -25 degrees C in liquid-frozen serum than they were in lyophilized serum. At -80 degrees C, trans-beta-carotene levels were stable for up to 3 years of storage in liquid-frozen serum. Both retinol and alpha-tocopherol appeared stable in liquid-frozen serum for at least 5 years at -80 degrees C. The effect of repeated freeze/thaw cycles on retinol, alpha-tocopherol, trans-lycopene, and trans-beta-carotene in liquid-frozen and reconstituted lyophilized serum both stored at -20 degrees C was also studied. Retinol, alpha-tocopherol, trans-lycopene, and trans-beta-carotene in reconstituted lyophilized serum stored at -20 degrees C were stable for at least 3 days with minimal (< 5) freeze/thaw cycles.
Language of Publication: English
Unique Identifier: 98430821

Return To Top
Return To Menu Position #90

MeSH Heading (Major): Anticarcinogenic Agents|*BL; Antioxidants|*AN; Beta Carotene|*BL; Carotene|*BL; Vitamin A|*BL; Vitamin E|*BL
MeSH Heading: Blood Banks; Blood Specimen Collection|MT; Drug Stability; Freeze Drying; Freezing; Human; Support, U.S. Gov't, P.H.S.; Time Factors

Publication Type: JOURNAL ARTICLE
ISSN: 0009-8981
Country of Publication: NETHERLANDS

Record 100 from database: MEDLINE
Return To Top
Return To Menu Position #90

Title: Vitamin D metabolism in human colon adenocarcinoma-derived Caco-2 cells: expression of 25-hydroxyvitamin D3-1alpha-hydroxylase activity and regulation of side-chain metabolism.
Author: Cross HS; Peterlik M; Reddy GS; Schuster I
Address: Department of General and Experimental Pathology, University of Vienna Medical School, Austria.
Source: J Steroid Biochem Mol Biol, 1997 May, 62:1, 21-8
Abstract: 1Alpha,25-dihydroxyvitamin D3 (1alpha,25(OH)2D3) and its synthetic analogues exhibit structure-related variations in their growth inhibitory actions in human colon adenocarcinoma-derived Caco-2 cells. Because this might be caused by differences in resistance against metabolic degradation, we used high performance liquid chromatography (HPLC) analysis to investigate pathways of vitamin D metabolism in two different Caco-2 cell clones. Importantly, when Caco-2 cells were incubated with tritium-labelled 25-hydroxyvitamin D3 (25(OH)D3) for up to 2 h they produced almost exclusively a metabolite, which was identified as 1alpha,25(OH)2D3 by co-chromatography with the synthetic standard in two different HPLC systems, and by a radioligand assay showing an identical binding affinity to the intestinal nuclear vitamin D receptor. Expression of the 25(OH)D3-1alpha-hydroxylase appears to be constitutive because almost identical enzyme activities are observed in any growth phase. 1Alpha,25(OH)2D3 can also activate side chain metabolism in Caco-2 cells: thereby, 1alpha,25(OH)2D3 or 25(OH)D3 are metabolized through the C-24 oxidative pathway into 1alpha,24(R),25(OH)3D3 and 24(R),25(OH)2D3, respectively, which undergo sequential metabolism into 1alpha,25(OH)2-24oxo-D3 and 24-oxo-25(OH)D3. Through C-23 oxidation these intermediary metabolites are further converted into 1alpha,23,25(OH)3-24-oxo-D3 and 23,25(OH)2-24-oxo-D3. Also direct C-23 oxidation of the substrates 1alpha,25(OH)2D3 and 25(OH)D3 generates 1alpha,23(S),25(OH)3D3 and 23(S),25(OH)2D3, respectively. In summary, our results demonstrated the presence of distinct pathways of vitamin D metabolism in Caco-2 cells: apart from metabolizing 1alpha,25(OH)2D3 along the C-24 and C-23 oxidative pathways, Caco-2 cells are able to synthesize 1alpha,25(OH)2D3 from 25(OH)D3 through constitutive expression of 25(OH)D3-1alpha-hydroxylase activity. The relevance of this finding for the intrinsic growth control of neoplastic colonocytes is discussed.
Language of Publication: English
Unique Identifier: 98031823

Return To Top
Return To Menu Position #90

MeSH Heading (Major): Adenocarcinoma|*ME; Colonic Neoplasms|*ME; Steroid Hydroxylases|*BI; Vitamin D|AA/*ME
MeSH Heading: Calcifediol|ME; Calcitriol|ME; Chromatography, High Pressure Liquid; Clone Cells; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Neoplastic; Human; Kinetics; Models, Chemical; Receptors, Calcitriol|ME; Support, Non-U.S. Gov't; Tumor Cells, Cultured

Publication Type: JOURNAL ARTICLE
ISSN: 0960-0760
Country of Publication: ENGLAND

Navigation Menu For The Book Life Flow One
Home Page Karl Loren's Book	Home Page Of The Data Section -- With Links To Each Separate Article	Shopping Cart To Purchase Oral Chelation Products From Karl Loren
Home Page Of The Karl Loren Writings Section -- With Links To Each Separate Item	Search The Entire Web Site Using The Professional Google Search Engine Especially Indexed For This Web Site	Home Page Of The Oral Chelation Web Site
Section One Who Will Die?	Section Two The Cholesterol Section	Section Three What Causes Heart Disease?
Section Four The Solution To Heart Disease	Section Five The Water Section	Section Six Ending Comments
Toxic Metals And Their Effects In The Body	The Role Of Free Radicals In Causing Disease	New Health Revelation
Ultimate Resource On Chelation Therapy		Technical Data On Heart Disease and Bypass Surgery
Table Of Contents In Each Of Three Different Sections:
TOC for Data References	TOC for The Book Itself	TOC For Karl Loren Articles
Go To The Vibrant Life Home Page Where Oral Chelation Vitamins Are Described And Sold

The Links Below Jump To Pages On Whatever Web You Are In
Table Of Contents	Search This Web		Navigation Help Page
Write To Karl Loren -- He Pledges To Answer EVERY Personal Message, Personally. Click here or on his name in the box below.
The Links Below Are To Various Web Sites Published By Karl Loren
Karl Loren Web	Vibrant Life Web		Karl Loren's Book
Super Colostrum	Bulk MSM		Heart Disease
Emmessar	Happiness		Arthritis
Instead Of	Chelation Therapy		Super Colostrum (2)
Karl Loren's Catalog Store		Central Page For All 12 Webs!

I promise to answer your message -- click here to send me a personal message

Dear Karl,

SUBSCRIBE: The Wednesday Letter is a free electronic monthly newsletter written and published by Karl Loren. You can view more than 50 back issues of this publication by clicking here. The Wednesday Letter subscription list is maintained on a secure server, no name is ever given or sold to anyone, and it is never used except for this Newsletter. It is automatically published on the Tuesday night just before the first Wednesday of every month. You can subscribe to this free monthly electronic letter by entering your eMail address and name below. You will then automatically receive a request for confirmation, sent to whatever address you have entered. If you do NOT receive this confirmation request, then you will not be subscribed. There may have been an error with your address and you should resubmit. The letter is never sent twice to the same address -- so you do not have to worry about a duplicate subscription. When you receive this confirmation request you must reply to it, or your subscription will not become active. No one can subscribe your name, and address, without you being notified, and if you get an unwanted notice of subscription you only need to DO NOTHING and the subscription will NOT be active.

REMOVAL: You can remove yourself from the subscription list in several different ways. Click here to read about this entire newsletter system. Every edition of The Wednesday Letter is delivered to your address with YOUR name and address in view on the letter, with a link that allows you to remove THAT name from the subscription list. If you try to send this removal message from an address different from the one you used to send in your original confirmation, then you will get a warning notice first, sent to the subscription address, asking you to confirm that you want to be removed from the list -- by replying to THAT request for confirmation, you will then be automatically removed. Thus, no one else can unsubscribe you, from some other computer, without your knowledge. But, if you send in the unsubscribe notice from the same machine used to receive the Letter, then the removal from the subscription list is automatic.

Personal Message: When you send a personal message to Karl Loren, you will receive a personal reply as per his instructions. Karl pledges that every personal message will get a personal answer. When you provide your mail address, we will send you free information including our free catalog and a cassette tape lecture by Karl Loren about heart disease, no charge, by mail, even if outside the US. You can select particular information you would like to receive, along with the free cassette tape and catalog.

Click here to add the Wednesday Letter as a Channel on your desktop. If your browser is so-equipped, you will be guided through a series of simple questions (about subscription information). Depending on your choices you can show the Vibrant Life Wednesday Letter as one of your "active channels" which will automatically download the new Wednesday Letter every month. In this way you can have the Wednesday Letter delivered to your desktop during the night (or your schedule) for immediate viewing in your browser. You can turn on or off this channel, at will, and delete the channel from your desktop at any time. With this feature operating you can click on the Wednesday Letter channel at any time to read the most recent copy of this electronic letter.

You can reach Vibrant Life in many ways, including by mail to Vibrant Life, 2808 N. Naomi St., Burbank, CA 91504. Within the US and Canada, use the toll free number: (800) 523-4521, the local number: (818) 558-1799, the FAX: (818) 558-7299, eMail to kimberly@oralchelation.com or any one of the hundreds of message forms throughout the 50 web sites. Vibrant Life normally ships the same day we get an order. There are message forms on each of the 100,000+ pages on this and other sites where you can communicate with Vibrant Life. Check out our companion site, at: http://www.oralchelation.net where Karl's 2000 page book is published. Karl Loren is the author and webmaster for this BOOK, as well as for another web site about ORAL CHELATION. His personal philosophical articles are at PHILOSOPHY.

Copyright © May 20, 2008 6:26 AM by Karl Loren on behalf of Vibrant Life, ALL RIGHTS RESERVED. Permission is granted for non-commercial downloading, copying, distribution or redistribution on two conditions: One, that some form of copyright notice is included in every copy distributed or copied, showing the copyright belonging to Vibrant Life, Burbank, CA, at www.oralchelation.com . The second condition is that the material is not to be used for any purpose contrary to the purposes and objectives of this site. This permission does not extend to materials on this site which are copyrighted by others.