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At least 1,225 records · Page 68Linked to original sources
PubMed1975

Breaking action of ascorbic acid on nucleic acids.

The lowering of the viscosity of DNA solution was caused by the action of AsA or EA and facilitated in the presence of CU2+. However, the action of AsA-3-P was very weak. By sucrose density gradient centrifugation, it was observed that single- and double-strand scissions of DNA were provoked by AsA or EA and enhanced with Cu2+, while only a single-strand scission was caused by AsA-3-P and Cu2+. Similar action of AsA or AsA-3-P was also observed for RNA. Thus, the result indicates that the enediol group of AsA takes an essential part in the breakage of nucleic acids, and Cu2+ enhances the action. It was shown that Apu was mainly decomposed by AsA, whereas Apy not, suggesting that some pyrimidine cluster may be one of the regions attacked by AsA. During the reaction with DNA, the reducing activity of AsA decreased first to some extent and then increased, whereas the reducing activity of AsA-3-P was much lower than that of AsA and decreased steadily. The priming activity of DNA for DNA polymerase was changed after treatment with AsA according to the condition. It was enhanced when DNA was treated under mild conditions but decreased with severer action.

Apurinic Acid↗
PubMed2001

Does ascorbic acid prevent retinopathy during interferon therapy in patients with chronic hepatitis C?

PURPOSE: Ascorbic acid was administered to patients with chronic hepatitis C to elucidate the mechanism of onset of retinopathy during interferon (IFN) therapy, and its prevention. METHODS: The subjects were 62 patients with chronic hepatitis C who had been admitted to our hospital. For the IFN therapy, 6 MIU of natural IFN-alpha, or 10 MIU of recombinant human IFN-alpha 2b was administered every day for the first 2 weeks, followed by administration three times a week for 22 weeks. The patients were randomly assigned to a group receiving 600 mg/day of ascorbic acid or a group not receiving ascorbic acid (control group). The optic fundi were examined by ophthalmologists before the IFN therapy began and subsequently at weeks 2 and 4 and then every 4 weeks during the IFN therapy. RESULTS: Retinopathy was found in 9 of the 31 patients (29%) in the ascorbic acid-treated group and in 11 of the 31 patients (35%) in the control group. The cumulative incidence of hemorrhage in the ascorbic acid-treated group was lower than that in the control group during the IFN therapy, but the difference between the two groups was not significant (P = 0.186). The cumulative incidence of cotton-wool spots in the ascorbic acid-treated group was almost same as that in the control group during the IFN therapy. The median platelet counts before the therapy was begun were 11.8 x 10(4)/mm2 in the group with hemorrhage and 16.6 x 10(4)/mm2 in the group without, and the lowest platelet counts during IFN therapy were 7.3 x 10(4)/mm3 in the group with hemorrhage and 9.5 x 10(4)/mm3 in the group without, indicating significantly lower values in the group with hemorrhage (P = 0.018 and P = 0.020, respectively). The lowest platelet counts during IFN therapy were 7.4 x 10(4)/mm3 in the group with cotton-wool spots and 9.7 x 10(4)/mm3 in the group without, indicating a significantly lower value in the group with cotton-wool spots (P = 0.036). CONCLUSIONS: Ascorbic acid was not considered to be useful for the prevention of the retinopathy associated with IFN therapy in patients with chronic hepatitis C.

Adult↗
PubMed1986

Ascorbic acid chronic alcohol consumption in the guinea pig.

Protection against the toxic effects of chronic alcohol consumption was observed in male guinea pigs maintained on a high-ascorbic-acid diet (vitamin C-deficient chow plus 2.0 mg ascorbic acid/ml drinking water) as compared to animals on a low-ascorbic-acid diet (vitamin C-deficient chow and from 0.025 to 0.050 mg ascorbic acid/ml drinking water). Alcohol was orally administered to the guinea pigs at a dose of 2.5 g/kg for up to 14 weeks. Levels of serum aspartate aminotransferase and serum alanine aminotransferase were significantly elevated in animals on the low-ascorbic-acid diet that received alcohol, 120 and 250%, respectively. In contrast, in animals on the high-ascorbic-acid diet that received alcohol, levels of alanine aminotransferase were not significantly elevated and levels of aspartate aminotransferase were elevated 50%. In addition, some of the animals on the low-ascorbic-acid diet that received alcohol for 12 to 14 weeks developed hepatic steatosis and necrosis, whereas none of the animals on the high-ascorbic-acid diet that received alcohol for the same length of time manifested these changes.

Administration, Oral↗
PubMed2003

Effect of ascorbic acid on stimulatory status of activated mouse peritoneal phagocytes.

Mouse peritoneal macrophages (MPM) when elicited by the antioxidant ascorbic acid have been found to be significantly stimulatory, exhibiting marked alteration at the cellular and enzyme levels. Alterations recorded were as follows--cellular yield per mouse, their protein content, lysosomal acid hydrolase levels and capability to phagocyte, all were significantly enhanced. The new stimulant was observed to produce no synergistic action on MPM when thioglycollate, BCG or endotoxin along with the same stimulated the latter. Levels of antioxidants like ascorbic acid and glutathione were found to be enhanced in elicited macrophages whereas superoxide dismutase levels varied when the three above stimulators were administered. However, the ascorbic acid elicited cells showed an increase in glutathione levels and a decrease in SOD levels but no change in total intracellular ascorbic acid levels. Further, though ascorbic acid interaction enhanced the phagocytic capability of MPM as compared to resident cells, no significant boosting of phagocytic process could be observed when each of three stimulators coupled with ascorbic acid was used for macrophage elicitation.

Animals↗
PubMed1999

Ascorbic acid and uric acid levels in lung cancer patients.

OBJECTIVE: To study any possible association between serum ascorbic acid and uric acid levels with lung cancer. METHOD: Serum ascorbic acid and uric acid levels in lung cancer patients (n = 30) and healthy controls (n = 45) were measured. RESULTS: The mean values for serum ascorbic acid were found to be significantly lower (P< 0.05) in patients (0.112+/-0.020) than in controls (0.394+/-0.029). Serum uric acid levels of patients were also significantly lower than those of controls (P< 0.05). CONCLUSION: There was no association between serum levels of ascorbic acid and uric acid, cholesterol, triglyceride and albumin levels with lung cancer.

Adult↗
PubMed1977

Chemical interactions between thiamin and tannic acid. I. Kinetics, oxygen dependence and inhibition by ascorbic acid.

Consumption of food high in tannins can cause thiamin deficiency. The interactions between tannic acid and thiamin were studied by allowing them to react at pH 7.5, 60 C, and determining free remaining thiamin by the thiochrome method and by recording changes in ultraviolet absorption profiles at intervals. The reaction was biphasic, having a rapid initial phase which was oxygen-independent, followed by a slower phase which was oxygen concentration-dependent. Ascorbic acid completely inhibited the reaction if present at the beginning of the reaction and could partially reverse the reaction if added during the first 30 min.

Antimetabolites↗
PubMed2000

Diethylmaleate decreased ascorbic acid release induced by cerebral ischemia in cerebral cortex of the anesthetized rat.

The effect of diethylmaleate administration on ascorbic acid release following cerebral ischemia was investigated in anesthetized rat brain cortex. Cerebral ischemia, induced by ligating bilateral common carotid arteries and unilateral middle cerebral artery, significantly increased the extracellular ascorbic acid levels. Diethylmaleate (4 mmoles/kg, i.p.), which has been shown in earlier studies to decrease the ischemia-induced glutamate release, significantly reduced the ischemia-induced ascorbic acid release. The ischemia-induced ascorbic acid release was unaffected by perfusing NMDA receptor antagonist MK 801 (75 microM). Additionally, elevated extracellular glutamate levels, achieved by either externally applied glutamate solutions or by perfusing L-trans-pyrrolidine-2,4-dicarboxylate (PDC) (31.4 mM and 15.7 mM) to inhibit the glutamate uptake transporter, also significantly increased the extracellular ascorbic acid levels. These results suggested that ascorbic acid release in cerebral ischemia might be related to the elevated extracellular glutamate levels, which occurs following cerebral ischemia.

Amino Acid Transport System X-AG↗
PubMed1975

Relation between hepatic alcohol dehydrogenase activity and the ascorbic acid in leucocytes of patients with liver disease.

1. Hepatic alcohol dehydrogenase activity and leucocyte ascorbic acid content was measured in thirty-five patients with liver disease and in ten control subjects with duodenal ulcer. The patients with liver disease were divided into three groups consisting of non-drinkers, moderate drinkers and alcoholic/heavy drinkers. 2. There was no significant difference in hepatic alcohol dehydrogenase activity between the groups with liver disease, but all patients had less than half the hepatic alcohol dehydrogenase activity of the control subjects (P less than 0-001). 3. The ascorbic acid in leucocytes was significantly lower in the alcoholic/heavy drinker group than that in the control subjects (P less than 0-02) when the Student's t-test was applied, but no significant difference was found when the Mann-Whitney U-test was used. 4. A correlation coefficient of r = 0-77 (P less than 0-001) was observed among the thirty-five patients with liver disease when hepatic alcohol dehydrogenase activity was compared with leucocyte ascorbic acid content. An insignificant correlation (r = 0-332) was found in the control subjects with no liver disease. 5. This comparison was also significant among non-drinkers with liver disease (r = 0-873; P less than 0-001), moderate drinkers (r = 0-739; P less than 0-02) and alcoholic/heavy drinkers (r = 0-702; P less than 0-005). 6. The addition of ascorbic acid in vitro (0-5-10 mmol/1) had no effect on the activity of alcohol dehydrogenase. 7. The relation between hepatic alcohol dehydrogenase activity and leucocyte ascorbic acid content is probably a consequence of liver disease, as opposed to any specific effect of ascorbic acid deficiency of alcohol consumption on alcohol dehydrogenase activity.

Alanine Transaminase↗