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Biomedical subjects

E Ginter

Publications and source records attributed to E Ginter.

At least 109 records · Page 6Linked to original sources

The effect of chronic marginal vitamin C deficiency on the rate of secretion and the removal of plasma triglycerides in guinea-pigs.

In guinea-pigs, chronic borderline vitamin C deficiency leads to hypertriglyceridaemia and to the accumulation of triglycerides in the liver. We investigated the triglyceride secretion rate by determining the rate of accumulation of triglycerides in the plasma following a Triton WR 1339 block of the their removal from the plasma (experiment 1) and the rate of the removal of triglycerides from the plasma by mathematical analysis of the specific plasma triglyceride activity - time curve after the administration of 3H-glycerol (experiment 2). In the 14th and 16th week of the experiment it was found that borderline vitamin C deficiency slowed down the triglyceride secretion rate, prolonged the half-time and reduced fractional plasma triglyceride turnover. The balance shift between the rate of the uptake and removal of very low density lipoprotein triglycerides (VLDL-TG) in the plasma compartment (greater retardation of the catabolic phase of kinetics) is probably the reason why triglycerides accumulate in the plasma and liver compartment of guinea-pigs with borderline vitamin C deficiency.

Animals↗

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↗

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↗

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↗

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↗

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↗