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Biomedical subjects

E Ginter

Publications and source records attributed to E Ginter.

At least 37 records · Page 2Linked to original sources
PubMed1989

Vitamin C lowers mutagenic and toxic effect of hexavalent chromium in guinea pigs.

The mutagenic effect of intraperitoneally injected K2Cr2O7 was significantly higher in vitamin C-deficient guinea pigs than in animals fed diet with high vitamin C content. Mutagenic and toxic effects of hexavalent chromium were more expressed in vitamin C-deficient guinea pigs administered K2Cr2O7 in drinking water: the number of micronuclei in polychromatic erythrocytes of bone marrow was increased, and the activity of O-demethylase and the levels of cytochromes P-450 and b5 in liver microsomes were decreased. In guinea pigs fed high vitamin C diet the same doses of bichromate in drinking water evoked no mutagenic changes in the bone marrow and no changes in microsomal enzymes in the liver. These results indicate that high intake of ascorbic acid in the diet reduces mutagenic effects of K2Cr2O7 and its toxic influence on drug metabolizing enzymes in hepatocytes. The protective effect ascorbic acid consists most probably in the enhanced extracellular and intracellular reduction of hexavalent chromium to the less toxic and less mutagenic trivalent chromium.

Animals↗
PubMed1988

Influence of age on the kinetics of vitamin C catabolism in guinea-pigs.

Pharmacokinetic analysis methods were used to evaluate the course of vitamin C catabolism in male guinea-pigs aged 3-5 weeks (weighting 255 g) and five months (weighing 570 g) given a diet containing no vitamin C. The vitamin C content of most of the organs and tissues of the younger experimental animals was depleted significantly more rapidly than in the older guinea pigs. At the same time, the half-time ascorbate elimination values were lower in the younger animals, in all the tissues analysed. As distinct from the older animals, vitamin C catabolism in the younger guinea-pigs had a biphasic character -- an extremely fast phase from the 1st to the 3rd day and a slower phase, comparable to the rate in older animals, from the 4th to the 17th day of administration of the scorbutogenic diet. The findings indicate that ascorbate metabolism in young organisms has specific characteristics, which ought to be taken into account when assessing and specifying the vitamin C requirements of the youngest section of the human population.

Age Factors↗
PubMed1979

Tissue levels and optimum dosage of vitamin C in guinea pigs.

Ascorbic acid mixed with the diet of guinea pigs achieved substantially higher maximum tissue concentrations of ascorbate than when ascorbic acid was administered orally once a day. A 0.5% w/w of ascorbic acid in the diet ensured a state close to maximal tissue steady-state levels of ascorbate. In guinea pigs fed a diet with a high content of saturated fatty acids or with 0.2% w/w of cholesterol, the highest rate of cholesterol transformation into bile acids and the lowest concentration of total lipids, cholesterol and triglycerides in blood serum and liver were found in the group fed a diet with 0.5% w/w of ascorbic acid as compared to the marginal-deficiency group and the group receiving 0.05% w/w of ascorbic acid in the diet. Maximal tissue steady-state levels of vitamin C are probably optimal for the guinea pigs' health.

Animals↗
PubMed1979

Effect of flavonoids on vitamin C activity of D-isoascorbic acid.

Large peroral doses of D-isoascorbic acid, a vitamin C stereoisomer (50 mg per animal per day), were retained in the guinea-pig organism to a smaller extent than the same doses of L-ascorbic acid (vitamin C). Simultaneous administration of the flavonoids rutin and epicatechin increased the amount of D-isoascorbic acid retained in the liver, brain and wall of the small intestine by up to 100%, but four weeks after its extraction from the food the amount of L-ascorbic acid left in the guinea-pig organism still exceeded D-isoascorbic acid reserves. This difference, which was found in all the organs studied, was the largest in the groups simultaneously given flavonoids. In guinea-pigs which, like man, are dependent on an exogenous vitamin C supply, D-isoascorbic acid was metabolized at a manifestly higher rate than L-ascorbic acid, irrespective of whether flavonoids were administered or not. In liver, brain and small intestine wall homogenates, the oxidized forms of both stereoisomers were reduced in the presence of reduced glutathione, but the reduction rate of D-isodehydroascorbic acid was higher and it was stimulated by the two flavonoids more strongly than the reduction of L-dehydroascorbic acid. The stuterospecific.

Adrenal Glands↗
PubMed1979

Natural hypocholesterolemic agent: pectin plus ascorbic acid.

An addition of 5% citrus pectin and 0.5% ascorbic acid to high-fat diet of guinea pigs prevented total cholesterol accumulation in blood serum and the liver. Two groups of persons were given a preparation containing a daily dose of 15 g pectin and 450 mg ascorbic acid for 6 weeks. In 21 healthy persons with mild hypercholesterolemia total serum cholesterol dropped significantly by 24 mg/100 ml (8.6%), while the concentration of high density lipoprotein cholesterol remained unchanged. In 11 hyperlipemic outpatients (type IIa, IIb and IV) total serum cholesterol dropped by 68 mg/100 ml (18.7%). The changes in triglyceridemia proved inconsistent.

Animals↗
PubMed1978

Effect of infrequent feeding and increased physical activity on cholesterol kinetics in the rat.

The authors studied the effect of chronic physical exercise (running in a rotating drum at 850 m/hour, 5 times a week for 16 weeks) on the size of the cholesterol body pools and on cholesterol kinetics in adult male Wistar rats fed on a standard diet either ad libitum or 2 hours daily [33 weeks]. These data were obtained by mathematical analysis of the curve expressing the correlation of specific plasma cholesterol activity to time after a single dose of cholesterol-4-14C. Chronic physical stress and infrequent feeding, as separate experimental stimuli, both caused cholesterol to shift from the blood plasma at a higher rate and reduced the size of one or both cholesterol body pools (with quick or slow turnover, pools A and B). Physical exercise also reduced fractional cholesterol turnover in pool A. When the two stimuli were combined, i.e. in infrequently fed and chronically stressed rats, the rate of the cholesterol shift from the blood plasma slowed down, the total and irreversible shift of cholesterol from pool A diminished and the production rate in this pool also fell.

Animals↗
PubMed1978

Hypocholesterolemic effect of ascorbic acid in maturity-onset diabetes mellitus.

A significantly lower vitamin C concentration has been found in the blood and particularly in the leukocytes of hypercholesterolemic diabetic patients than of healthy blood donors. Ascorbic acid administered in a dose of 500 mg per day for 12 months to metabolically stabilized hypercholesterolemic subjects with maturity-onset diabetes mellitus (diabetic diet without insulin or diabetic drugs) brought about a striking decline of cholesterolemia and a moderate decline of triglyceridemia. The serum lipid level in the control group given placebo remained unaltered. A daily administration of 500 mg of ascorbic acid for six months failed to affect the fasting level of serum immunoreactive insulin. It is assumed that the long-term administration of ascorbic acid to maturity-onset diabetics removed the tissue ascorbate deficiency and improved the liver ability to compensate the increased endogenous synthesis of cholesterol by its enhanced transformation to bile acids.

Ascorbic Acid↗