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Biomedical subjects

S Krishnamurthy

Publications and source records attributed to S Krishnamurthy.

At least 145 records · Page 8Linked to original sources
PubMed1983

Effect of dietary coconut oil and casein and megadoses of vitamin A or C on tissue lipid peroxidation and hemolysis in vitamin E deficiency.

Male rats fed on pellet diet to an average weight of 105 g were placed on a vitamin E deficient diet containing 20% coconut oil for a period of 12 weeks at two dietary protein levels, 20% and 10% casein. Rats on 20% casein diet showed a definite weight loss but not so at the 10% casein level. A marked increase in the liver in vitro lipid peroxidation was observed at both protein levels. Feeding of retinyl palmitate at 100,000 IU/100 g body weight for 4 consecutive days inhibited the liver, brain and kidney in vitro peroxidation; megadoses of ascorbic acid produced less inhibition of the liver peroxidation, but the same degree of inhibition for brain and kidney peroxidation as in vitamin A loaded rats. Both dietary palmitate or ascorbic acid. Acetylcholine esterase and ATPase, two of the membrane enzymes of erythrocytes, were depressed in all the groups. The glutathione content of erythrocytes was increased in rats given ascorbic acid. In all the groups the higher dietary protein levels produced greater loss of body and tissue weights. It is concluded vitamin E deficient diet supplemented with dietary coconut oil (saturated fat) induces increased in vitro lipid peroxidation and oxidative lysis of erythrocytes and that megadoses of vitamin A or C suppress the in vitro lipid peroxidation but enhance the lysis.

Animals↗
PubMed1982

Noncontraceptive estrogen use and the occurrence of ovarian cancer.

Female residents of six counties in Washington and Utah in whom ovarian cancer was diagnosed during 1975-79 were interviewed concerning prior use of noncontraceptive estrogens. Interviews with a random sample of women drawn from these counties were obtained for comparison. Taken as a whole, women with epithelial ovarian tumors reported estrogen use for 1 year or more somewhat more often than did controls [relative risk (RR) = 1.3, 95% confidence interval (CL) = 0.9-1.8]. The proportion of women who had used estrogens varied according to the histology of their tumor; notably, of 17 women with endometrioid tumors, 12 had used estrogens (RR = 3.1, 95% CL = 1.0-9.8). The excess risk of endometrioid carcinoma related to estrogen use was not further increased when these hormones were taken for long durations, in high doses, or proximate to the time of diagnosis. Neither was there any evidence of increased risk from estrogen use in the small group of women with clear cell tumors, a histologic tumor type believed to be closely related to endometrioid carcinoma. Thus the observed association between menopausal estrogen use and the occurrence of ovarian endometrioid tumors should be interpreted cautiously until the results of additional studies are available.

Adenocarcinoma↗
PubMed1982

Effect of dietary protein and hypervitaminosis A or C on tissue peroxidation and erythrocyte lysis of vitamin E deficiency.

Rats were maintained on a vitamin E free diet containing 20% safflower oil for a period of 12 weeks at two dietary protein levels, 20% and 10% casein. Enhanced in vitro tissue lipid peroxidation and lysis of erythrocytes were noticed at both the protein levels. A reduction in body mass and tissue weights were observed in both the protein groups but more so at 20% protein level. Feeding of retinyl palmitate (100 000 IU/100 g body weight) for 4 consecutive days to -E rats inhibited liver and kidney in vitro lipid peroxidation. Ascorbic acid (150 mg/100 g body weight) given orally for 5 days to -E rats inhibited liver brain and kidney in vitro peroxidation. Lysis of erythrocytes from -E rats was further increased by dosing with both the vitamins "A" and "C", the latter being more effective. The stromal enzymes acetyl choline esterase and ATPase were lowered, following the hemolysis profile of the erythrocytes from the different groups. Glutathione content of erythrocytes were unaffected except in -E +C group. In all groups the higher protein level (20%) produced greater lysis as compared to 10% level. It is concluded that 20% protein is more injurious in vitamin E deficiency simultaneously made hypervitaminosis A or C.

Animals↗
PubMed1979

Metabolism of drugs and carcinogens in man: antipyrine elimination as an indicator.

The suitability of the most commonly used "prototype" drug, viz, antipyrine, in predicting drug and carcinogen metabolism was evaluated, by studying in vivo antipyrine elimination rate (Ke) and in vitro metabolism of drugs and carcinogens in liver preparations in the same individuals. Our subjects were 20 adult males undergoing abdominal surgery for gastrojejunostomy, although antipyrine Ke could be studied in only 16 subjects. Correlations of the various in vito--in vivo parameters were positive between the parameter pairs: in vivo antipyrine Ke--in vitro benzopyrene hydroxylase; benzopyrene hydroxylase--aniline hydroxylase; and benzopyrene hydroxylase--gamma-glutamyl transferase. Aminopyrine demethylase did not correlate with any of the parameters studied. The degree of correlation between antipyrine Ke and benzopyrene hydroxylase was statistically significant but was not satisfactory for predictive purposes. Our study indicates some of the problems and limitations of in vivo--in vitro comparisons and confirms earlier doubts on the usefulness of antipyrine as a "prototype" drug for predicting drug and carcinogen metabolism in man.

Adult↗
PubMed1979

Effect of lipid antioxidants on rat erythrocyte hemolysis.

Lipid antioxidants, DPPD, DAH, BHT, SQ, retinol and alpha-tocopherol were studied for their effects on normal rat erythrocytes. Retinol, BHT and SQ were found to induce hemolysis while DPPD, DAH and alpha-tocopherol were non-hemolytic. Further more the three antioxidants BHT, SQ and retinol showed a synergistic effect on the lysis. Retinol, BHT or SQ alone, and BHT or SQ along with retinol when administered to rats produced a marked modification of the erythrocyte membrane integrity, simultaneously lowering the levels of membrane bound enzymes--acetyl choline esterase and ATPase. It is concluded that the lipid antioxidants may therefore be classified on the basis of their lytic action in vitro.

Animals↗
PubMed1978

Effect of vitamins, antioxidants and sulfhydryl compounds on in vitro rat brain lipid peroxidation.

The effect of retinol, retinylacetate, alpha-tocopherol, alpha-tocopherylacetate, synthetic antioxidants (DPPD, BHT, DAH, and Ethoxyquine) sulfhydryl compounds (reduced glutathione and cysteine) on rat brain lipid peroxidation has been studied using the TBA method. Retinol and retinyl acetate inhibit brain lipid peroxidation, alpha-tocopherol is less effective than vitamin A, while alpha-tocopherol acetate has no antioxidant property. Ascorbic acid stimulates the peroxidation, at pH 5.0. The synthetic antioxidants are all potent inhibitors of brain lipid peroxidation, DPPD being the most effective, while the sulfhydryl compounds at a concentration of 1 x 10(-3)M has a slight potentiating effect.

Animals↗
PubMed1978

Effect of hypervitaminosis A on hemolysis and lipid peroxidation in the rat.

Erythrocytes from rats fed large doses of Vitamin A alone, or large doses of vitamin A and vitamin E or diphenyl-p-phenylene diamine (DPPD) were studied for H2O2-induced hemolysis. The vitamin A-dosed rats were more susceptible than normal rats to H2O2-induced hemolysis. Hemolysis was not accompanied by lipid peroxidation. Nevertheless, the antioxidants vitamin E and DPPD inhibited hemolysis in erythrocytes from vitamin A-dosed rats. These antioxidants had the same inhibitory effect when they were included in the diet or added to erythrocyte suspensions in vitro. Erythrocytes from vitamin A-dosed rats with or without added vitamin E or DPPD were less susceptible than the erythrocytes from normal rats to osmotic challenge, showing that vitamin A was present in levels sufficient to alter the structure of the erythrocyte membrane. These studies show that oxidative hemolysis occurs when the erythrocyte membrane is modified. Furthermore, this oxidative hemolysis is unrelated to lipid peroxidation.

Animals↗
PubMed1977

Antioxidant function of vitamin A.

Feeding of 100 000 I.U. of Vitamin A on alternate days, five times to rats, resulted in a marked lowering in in vitro lipid peroxidation of the tissue hemogenates. alpha-Tocopherol or DPPD supplementation along with A still further reduced the in vitro lipid peroxidation of the tissues. Vitamin A in large doses increased the antioxygenic potential of the tissues, and it is suggested that retinol also might be considered as a potential antioxidant similar to tocopherol in animal nutrition.

Alopecia↗