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Biomedical subjects

B Leibovitz

Publications and source records attributed to B Leibovitz.

8 recordsLinked to original sources
PubMed1990

Dietary supplements of vitamin E, beta-carotene, coenzyme Q10 and selenium protect tissues against lipid peroxidation in rat tissue slices.

A tissue slice model was employed to assess the effects of dietary antioxidant supplements on lipid peroxidation. In one experiment, rats were fed diets containing, either alone or in combination, vitamin E, selenium, beta-carotene or coenzyme Q10 for 42 d, and the extent of spontaneous and induced lipid peroxidation was determined by release of thiobarbituric acid-reactive substances (TBARS) into the medium. Vitamin E exhibited the greatest protection against lipid peroxidation in liver, heart and spleen; in kidney, selenium was most protective. Coenzyme Q10 was active against lipid peroxidation induced by tertbutyl hydroperoxide (t-BHP). In a second experiment, rats were fed diets containing varying amounts of vitamin E, selenium, beta-carotene and coenzyme Q10 for 30 d. Spontaneous lipid peroxidation in liver, kidney and heart decreased with increasing levels of dietary antioxidants. With increasing amounts of antioxidants, there was a diminution in TBARS released by liver and kidney slices incubated with t-BHP; in heart, only the highest levels of antioxidants significantly decreased production of TBARS. Inverse correlations between dietary vitamin E and TBARS, tissue vitamin E and TBARS, and tissue selenium-glutathione peroxidase and TBARS were highly significant. The procedure used here can evaluate dietary supplements that may find practical applications in decreasing the oxidant radical portion of disease processes.

Animals↗
PubMed1986

Bioassay of environmental nickel dusts in a particle feeding ciliate.

The ciliated protozoan Paramecium was used to quantitate cytotoxic and genotoxic effects of nickel particles. The biological response of these eukaryotic cells to pure nickel powder and iron-nickel powder was assayed and compared to the effect of the inorganic carcinogen nickel subsulfide. Cytotoxicity was determined by the percent survival of treated cells. Genotoxicity was indicated by significant increases in the fraction of nonviable offspring (presumed index of lethal mutations) found after self-fertilization (autogamy) in parents from the nickel-treated versus neutral control groups. The cells were exposed to the dusts and the biological effects determined. Only the nickel subsulfide consistently showed a significant increase in offspring lethality.

Biological Assay↗
PubMed1982

Enhancement of antibody production and protection against systemic anaphylaxis by large doses of vitamin C.

Male and female guinea pigs receiving, respectively, 100 and 280 mg/day Vitamin C throughout the duration of immunization showed enhanced humoral antibody production to bovine serum albumin (BSA) and, in castrated females, to penicilloyl-coupled guinea pig gamma-globulin. A significant degree of protection was afforded against fatal anaphylactic shock in passively sensitized males. Under appropriate conditions of sensitization with rabbit anti-HGG and challenge with human gamma-globulin, 8 of 20 unsupplemented animals died of shock, whereas in the group receiving 280 mg Na ascorbate/day for 4 days preceding passive transfer and again 60' before challenge, only 2 of 18 died. The rate of dose-dependent mortality observed when groups of passively sensitized animals were challenged with increasing doses of antigen was reduced in animals supplemented as above. Actively immunized guinea pigs were not protected by 5 daily doses of 280 mg Na ascorbate given prior to challenge. There were no significant differences in the total hemolytic activity of the serum nor in the C3 and C4 components of complement in immunized animals. There was no change in the concentration of Cl esterase in non-immunized controls, but immunization with BSA was followed by a rapid decline in Cl concentration, the decrease being greater in the ascorbate-treated group than in the unsupplemented controls, possibly reflecting a higher level of circulating immune complexes in the former case.

Anaphylaxis↗
PubMed1979

Ascorbic acid and cancer: a review.

Host resistance to neoplastic growth and invasiveness is recognized to be an important factor in determining the occurrence, the progress, and the eventual outcome of every cancer illness. The factors involved in host resistance are briefly reviewed, and the relationship between these factors and ascorbic acid metabolism is presented in detail. It is shown that many factors involved in host resistance to neoplasia are significantly dependent upon the availability of ascorbate.

Animals↗
PubMed1978

Ascorbic acid, neutrophil function, and the immune response.

The role of ascorbic acid is reviewed with regard to antimicrobial activity, interferon production, and humoral and cellular immune responses. Ascorbic acid appears to play a role in a number of neutrophil functions including increased chemotaxis, increased particulate ingestion, enhanced lysozyme-mediated non-oxidative killing, protection against the toxic effects of superoxide anion radical, inhibition of the halide-peroxide-myeloperoxidase system without a pronounced bactericidal effect, and stimulation of the hexose monophosphate shunt.

Animals↗