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Biomedical subjects

A L Tappel

Publications and source records attributed to A L Tappel.

At least 145 records · Page 8Linked to original sources
PubMed1977

Effects of selenite and selenomethionine on glutathione peroxidase in the rat.

The activity of glutathione (GSH) peroxidase (EC 1.11.1.9) decreased in tissues of rats fed a diet deficient in selenium. A single dose of 300 mug selenium by stomach tube increased GSH peroxidase activity within 48 hours. The effects of selenite and selenomethionine on GSH peroxidase activity were roughly similar. This study provides evidence that selenium from both selenite and selenomethionine is readily available for synthesis of the selenoenzyme GSH peroxidase in rat tissues.

Animals↗
PubMed1976

Purification and properties of rat lung soluble glutathione peroxidase.

Gluthathione peroxidase (gluthatione:hydrogen-peroxide oxidoreductase, EC 1.11.1.9) has been purified approximately 2700-fold from rat lung soluble fraction. The purified enzyme was shown to be homogeneous by sodium dodecyl sulfate/urea polyacrylamide gel electrphoresis. Selenium-75 tracer cochromatographed with the enzyme activity, indicating that rat lung soluble gluthathione peroxidase is a selenium enzyme. The enzyme had an approximate molecular weight of 80000 and contained four identical subunits. The optimal activity of the enzyme was at between pH 8.8 and 9.1. The enzyme had general specificity toward hydroperoxides, and high specificity for reduced glutathione. The kinetic behavior or the purified lung soluble glutathione peroxidase followed a ping-pong-like mechanism; the enzyme first reduced the lipid hydroperoxide substrate to the corresponding hydroxy fatty acid, then was regenerated to the native form by reduced glutathione.

Animals↗
PubMed1976

Sensitive fluorometric method for tissue tocopherol analysis.

A sensitive, highly reproducible method for tissue tocopherol analysis that combines saponification in the presence of large nmount of ascorbic acid to remove interfering substances, extraction fo the nonsponifiable lipids with hexane, and fluorometric measurement of the tocopherol is presented. The nonsaponifiable lipids phase contained only one fluorochrome in the 290 am excitation and 330 nm emission range, and it was identified as tocopherol by thin layer and column chromatography. Column chromatography of the hexane extract of a saponified, 14C-tocopherolspiked microsomal fraction showed that no measurable oxidation to tocopherylquinone had occurred. The flurometric method for tocopherol analysis was applied to homogenates and subcellular fractions from rat liver, kidney, lung, and heart and red blood cells. The heavy mitochondrial and microsomal fractions had the highest subcellular concentrations of tocopherol.

Animals↗
PubMed1975

Fluorescent pigments from uterus of vitamin E-deficient rats.

Spectrophotofluorometric analyses of the extracts of uterus from sterile rats maintained on a vitamin E-deficient diet for a prolonged period of time indicated that the brown ceroid-like pigments present were highly fluorescent, having characteristics typical of products formed during lipid peroxidation in vivo. The aqueous-methanol layer of the uteral extract from vitamin E-deficient animals had higher fluorescence than the corresponding chloroform layer, indicating the presence of more polar water-soluble pigments than those found in most other tissues so far examined.

Animals↗
PubMed1975

Fluorescent products and polyunsaturated fatty acids of human testes.

Lipid soluble fluorescent pigments from human testis were fractionated by silicic acid column chromatography and silica gel thin layer chromatography. Fluorescence analyses revealed a family of at least 3 compounds with similar fluorescence properties, including excitation and emission maxima, reversible fluorescence quenching by alkaline pH, and fluorescence quenching by heavy metal chelation. These fluorescence characteristics strongly indicated the presence of the conjugated Schiff base fluorophore-N=C-C=C-N-. The chromatographic separations employed enabled a more definitive fluorescence characterization of the lipid soluble pigments known to accumulate late in tissues with age and as a result of lipid peroxidation. Total lipids and fatty acid composition of the total lipids were determined. Polyenoic acids constituted about 40% of the total fatty acids. Histological examination of the tissues revealed some degeneration and edema, but significant spermatogenesis and normal complement of Leydig cells.

Age Factors↗
PubMed1975

Distribution of dipeptidase activity between lysosomes and soluble fraction of rat liver.

Dipeptidase activity toward Arg-Phe, Arg-Gly, and Trp-Leu exhibited bimodal distribution in the lysosomal and soluble fractions of rat liver. The majority (50-70 percent) of the dipeptidase activity was present in the soluble fraction. Some evidence for a plasma membrane dipeptidase, which hydrolyzes Trp-Leu but not Arg-Phe or Arg-Gly, also was found. The lysosomal dipeptidase activity had a pH optimum of 6.0-7.0, and was activated by sulfhydryl reagents. Lysosomal localization for some of the dipeptidase activity was established with Triton WR-1339 fractionation and latency experiments.

Animals↗
PubMed1975

Effect of cadmium chloride on the rat testicular soluble selenoenzyme, glutathione peroxidase.

Thirty-six hours after male rats were injected with 25 mumoles cadmium chloride/ml/kg of body weight they exhibited decreased plasma and testicular glutathione (GSH) peroxidase activity, testicular atrophy and necrosis, and increased testicular thiobarbituric acid-reactive products. Seven days after injection, only the plasma GSH peroxidase activity returned to normal. The decrease in testicular GSH peroxidase activity was not reversible by dialysis against buffer or by the addition of selenium as buffered selenomethionine. In vitro inhibition of testicular GSH peroxidase activity occurred at 0.3 mM cadmium. All in vivo effects were prevented by a prior injection of 25 mumoles sodium selenite/ml/kg of body weight. Testicular GSH peroxidase may be the direct or indirect target of cadmium-induced testicular damage, and this damage results in lipid peroxidation.

Animals↗