Kidney selenium

A summary of the influence of selenium on deposition of mercury in rat tissues is presented in Table III. In the injection experiments, selenium caused a reduction in mercury deposition in the kidneys of rats given either inorganic or organic mercury. The reduction in kidney mercury is dependent upon the level of selenium injected and the chemical form of selenium (Fang, 1977). Selenomethionine was most effective in reducing the renal mercury content, followed by selenocystine, selenate, and selenite. In contrast to the kidneys, selenium usually resulted in an increased deposition of mercury in other tissues. It is of particular interest that selenium appears to be very effective in increasing methylmercury deposition in the brain. When included in the diet, selenium also causes an increased deposition of hepatic mercury. This is consistent with the results of selenium injection experiments. Deposition in the kidney may depend upon the level in the diet. At low mercury levels, selenium resulted in decreased levels in the kidneys but in increased levels at... 

In an adequately supplied adult male human subject, the total body selenium content is on the order of 30-60 mg, of which one-third is found in the skeleton and two-thirds in the soft tissues. A substantial fraction of kidney selenium is retained even when selenium at other sites is severely depleted during deficiency, and renal selenium is more constant between human populations than selenium in other tissues or body fluids. Regulation of selenoprotein synthesis at the transcription level appears to ensure a hierarchy of preservation of individual selenoproteins at critical sites. The cytosolic glutathione peroxidase (GPx I) and selenoprotein P can donate selenium to other sites whenever overall depletion occurs. Selenium crosses the placenta readily, and breast milk selenium concentration is responsive to changes in maternal selenium intake. In the United States, breast milk Se concentrations are generally in the range of 0.19-0.25 pmol/1, but colostrum has levels that are two or three times higher than those of mature breast milk. 

Selenium heterocycles receive far less mention in the literature than do such homologs as oxazole, thiazole, or imidazole. In fact, preparative methods of selenium heterocycles are much more limited than for the other series, mainly because of manipulatory difficulties arising from the toxicity of selenium (hydrogen selenide is even more toxic) that can produce severe damage to the skin, lungs, kidneys, and eyes. Another source of difficulty is the reactivity of the heterocycle itself, which can easily undergo fission, depending on the reaction medium and the nature of the substituents. 

Selenium. Selenium, thought to be widely distributed throughout body tissues, is present mostly as selenocysteine in selenoproteins or as selenomethionine (113,114). Animal experiments suggest that greater concentrations are in the kidney, Hver, and pancreas and lesser amounts are in the lungs, heart, spleen, skin, brain, and carcass (115). 

Baker, M. A. and Tappel, A.L. (1986) Effect of gold thioglucose on subcellular selenium distribution in rat liver and kidney. Biological Trace Element Research, 9, 113-123. 

The effects of antioxidants on protein oxidation were also studied in animal experiments. Barja et al. [73] demonstrated that feeding guinea pigs with vitamin C decreased endogenous protein oxidative damage in the liver. Administration of the mixture of antioxidants containing Trolox C, ascorbic palmitate, acetylcysteine, (3-carotene, ubiquinones 9 and 10, and (+)-catechin in addition to vitamin E and selenium to rats inhibited heme protein oxidation of kidney homogenates more efficiently than vitamin E + selenium [74]. 

Jorhem, L., B. Sundstrom, C. Astrand, and G. Haegglund. 1989. The levels of zinc, copper, manganese, selenium, chromium, nickel, cobalt, and aluminium in the meat, liver and kidney of Swedish pigs and cattle. Zeit. Lebens.-Unters. -Forschung 188 39-44. 

Drinking water of weanling males contained 150 mg CN/L for 9 weeks Significant reduction in glutathione activity, and in selenium concentrations in blood, kidney, liver, and muscle 35... 

Elevated selenium concentrations were measured in tissues and diet of two captive California sea lions (Zalophus californianus) that died shortly after performing at a show in 1988. Selenium concentrations, in mg/kg FW, were 49 and 88 in liver, 42 and 47 in kidney, and 5.1 and 5.2 in blood. Selenium concentrations in their fish diet was 2.5 mg/kg FW, and in thawed fish fluids 45 mg/kg FW (Alexander et al. 1990). 

Selenium lessens the toxicity of divalent mercury in animals, the protection being less at continuous mercury exposure. Selenium has been found to affect the distribution of mercuric mercury in mice [134], rats [135], rabbits [136, 137] and pigs [ 138]. Mercury forms a mercury-selenium protein complex with selenium with little biological activity [139]. Mercury is thus retained longer in the blood, liver and spleen and as a consequence lessens accumulation in the kidney. In fish, selenium pretreatment probably retarded mercury uptake rather than promoting mercury excretion [140]. 

Selenium is readily available in a variety of foods including shrimp, meat, dairy products, and grains, with a recommended daily intake of 55 to 70 jug. It occurs in several forms with Se+6 being biologically most important. Selenium is readily absorbed by the intestine and is widely distributed throughout the tissues of the body, with the highest levels in the liver and kidney. It is active in a variety of cellular functions and interacts with vitamin E. Selenium appears to reduce the toxic effects of metals such as cadmium and mercury and to have anticarcinogenic activity. Selenium produces notable adverse effects both in deficiency and excess thus recommended daily intake for adults is approximately 70 Jg/day but should not exceed 200 pg/day. 

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