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PubMedDate not supplied

[Activation of lipid peroxides in the liver during hypokinesia and its prevention by antioxidants].

Experiments on white rats showed that exposure to hypokinesia increased peroxidation of unsaturated fatty acids of lipids of cell membranes, decreased the content of sulfhydryl groups, and increased the content of disulphide groups. This was very marked during the first 4-7 days, i.e., during the time of a distinct stress-reaction. At later stages the rate of free radical processes decreased slightly. In the recovery period that followed 7-day hypokinesia lipid peroxidation in the rats gradually returned to normal. The initiation of free radical reactions during hypokinesia can be prevented by means of antioxidants (acetate tocopherol, sodium selenite) and syrepar.

Animals↗
PubMed1985

Methylthio-capping of selenocysteamine: preliminary studies on selective toxicity for cancer chemotherapy.

Dimethyl disulfide markedly increased the cytotoxicity of selenocystamine by 2 orders of magnitude, from 40 microM to 0.5 microM for 50% inhibition of growth in 45 hr. When mice were injected ip with 22 microMole/Kg of selenocystamine on Day 0, all were dead on Day 4. If dimethyl disulfide (500 microMole/Kg) was either mixed with the selenocystamine or injected immediately prior to it, the mice survived treatment for at least 21 days afterwards, suggesting that methylthio-capping of selenocysteamine reduced host toxicity. Such combined treatment may be of value in chemotherapy.

Animals↗
PubMed1978

Growth characteristics and drug responses of a murine lung carcinoma in vitro and in vivo.

Cells obtained from the Nettesheim lung carcinoma of DBA/2 mice, a heterogenous population grown s.c., were cultured as monolayers. These cells were serially subcultured and cloned twice, and a clone was selected for further study. This clone produced malignant tumors at the injected site when injected s.c. into male DBA/2 or C57BL/L x DBA/2 F1 mice. Referred as KLN205, this cell line had the highest rate of lung colony formation on i.v. injection. It was subcultured for over 15 generations, and its cytological characteristics were investigated. The s.c. and lung colony growth were examined histologically. The effects of treatment with two antimetabolite drugs, arabinosyl-6-mercaptopurine (NSC 406021) and 6-selenoguanosine (NSC 137679) were determined in culture and in vivo. The former was relatively ineffective; the latter was very effective both in vivo and in vitro. Several drugs used clinically for the treatment of lung cancer were also tested. This established and characterized cell line is proposed as a potential model for testing other chemotherapeutic treatments.

Animals↗
PubMed1979

Effects of separate and combined chronic mercuric chloride and sodium selenate administration in rats: histological, ultrastructural, and x-ray microanalytical studies of liver and kidney.

The separate administration of mercuric chloride (HgCl2) and sodium selenate (Na2SeO4) to male rats in drinking water or a combined administration of both (50 ppm Hg, 15 ppm Se) caused different signs of toxicity over a 22 week period. The HgCl2 group showed histopathological and ultrastructural lesions as evidenced by periportal fatty degeneration and cell necrosis in the liver and tubular necrosis with proteinaceous casts in the kidney. The Na2SeO4 group showed the most severe depression of growth and food and water consumption, but no pathological changes were seen in the liver or kidney. Simultaneous administration of both toxicants produced a protective effect on weight loss and histopathology. These effects were associated with the formation of electron dense nuclear inclusions in kidney proximal tubule cells and similar electron dense formations in the reticuloendothelial cell cytoplasm and in the extracellular space of Disse in the liver. These formations were shown to contain both Se and Hg by energy dispersive X-ray microanalysis. The basis of the protective interaction of these two elements appears to result from an alteration of the chemical form or association of the mercury and selenium.

Animals↗
PubMed1984

Prevention of cancer: practical prospects.

The discovery of some 40 specific factors that have caused cancer in humans has demonstrated conclusively that many fatal cancers are capable of being prevented. These known factors are responsible for less than half all fatal cancers in all countries and much less in most; but there is good evidence, derived from the variation in the incidence of cancer in different communities, in different countries, and at different times that in many countries it may be possible to prevent 80% of all cancers or even more. The practical problems facing each country are different. Not only are the types of cancer different that need most urgently to be prevented, but so are the social and economic conditions that permit or constrain the introduction of preventive measures. Well-understood measures are summarized and the prospects for others that are less established or as yet untried are discussed, including the use of low-tar cigarettes, dietary modification, and anti-viral vaccines.

Aflatoxins↗
PubMed1983

Transport systems for lysine, thialysine and selenalysine in E. coli KL16.

Two lysine transport systems have been identified in E. coli KL16. They differ in their affinity for lysine, one showing a KM of 0.36 microM and the other a KM of 4.7 microM. Different compounds with chemical similarities to lysine were tested for their capacity to interfere with lysine transport. Among these only thialysine and selenalysine competitively inhibit lysine transport. The inhibition is on both transport systems. Thialysine shows a KI of 4 microM for the low affinity system and a KI of 8 microM for the high affinity system. Selenalysine shows values of 6 microM and 12 microM respectively.

Biological Transport↗
PubMed1984

Selenium inhibition of DNA synthesis in mouse mammary epithelial cell line YN-4.

Previous results have documented that Na2SeO3 has a biphasic effect on the growth of mammary cells in vitro. In the experiments reported herein, the effects of selenium on several parameters of cell proliferation in the YN-4 mouse mammary cell line were investigated. The biphasic effect of selenium on cell growth was confirmed; i.e., 5 X 10(-8) M selenium stimulated cell growth, whereas 5 X 10(-6) M delayed cell growth and 5 X 10(-5) M was cytotoxic. The inhibition of cell growth by 5 X 10(-6) M selenium was reversible when this dose was removed from the growth medium. The increased cell growth at 5 X 10(-8) M selenium was reflected by an increased cell number, increased uptake of [3H]thymidine into DNA, increased DNA labeling index, and an increased rate of DNA synthesis. The decreased cell growth at 5 X 10(-6) M selenium was reflected by a decrease in all of these parameters of cell growth kinetics. The differential effects of selenium were manifested by 48 hr after addition of selenium to the cell culture medium. The results indicate that one of the mechanisms of selenium-mediated inhibition of carcinogenesis may be due to an inhibition of cell proliferation of responsive cells.

Animals↗
PubMedDate not supplied

[Effectiveness of vitamin E and sodium selenate in carbon tetrachloride-induced liver damage depending on the season].

Seasonal features of the efficacy of antioxidants for liver poisoning with carbon tetrachloride (CCl4) were revealed in 175 random-bred male rats. Liver function was appraised according to the bile secretion characteristics (bile secretion rate, the level of bile acids, cholesterol and bilirubin in bile). It was discovered that CCl4 hepatotoxicity was the highest during spring and summer. Vitamin D was more efficacious in spring and summer, whereas sodium selenite in autumn and winter. The use of combined vitamin E and sodium selenite prevered the toxic action of CCl4 on the liver in autumn, winter and spring and minimized it in summer. The mechanisms of seasonal differences in the action of CCl4 on the liver and antioxidant efficacy for damage in question are discussed. The conclusion was made about an important role of the time factor in the prophylaxis and treatment with antioxidants of liver toxic damages.

Animals↗