Selenium content of human milk,cow's milk and cow's milk infant formulas

The selenium content of human milk, cow's milk and cow's milk infant formula were estimated by instrumental neutron activation analysis. The highest values were found in 3 samples of human colostrum (524–865×10^-9 g/g dry weight). There was a significant decrease with increasing time post partum. Mature human milk exhibited a selenium content of 230±79×10^-9 g/g dry weight.The selenium content of 45 samples of cow's milk from the north-western area of Germany was 200±39×10^-9 g/g dry weight. While there was no significant difference between the values of mature human milk and of cow's milk, cow's milk infant formula exhibited significantly (P<0.01) lower values than human milk. The average selenium content of 107 samples of 10 different commercially available fluid and powdered cow's milk infant formulas (range: 18–171×10^-9 g/g dry weight) amounted to about only one third of that in mature human milk.With support of the Deutsche Forschungsgemeinschaft     

Plasma glutathione peroxidase after selenium supplementation in patients with reduced selenium state

The plasma glutathione peroxidase (GSHPx) activity was measured in normal adults and children and in patients with reduced selenium state because of dietary treatment of metabolic diseases (phenylketonuria or maple-syrup-urine disease) before and after selenium supplementation. Besides GSHPx (measured with t-butyl hydroperoxide, cumene hydroperoxide and hydrogen peroxide as acceptor substrates) the activity of glutathione S-transferase was estimated in plasma. Plasma GSHPx activity in healthy children was significantly lower than in healthy adults. In 11 dietetically treated patients with phenylketonuria or maple-syrup-urine disease the plasma GSHPx was reduced to about 17% of the values of healthy children of the same age. No glutathione S-transferase activity could be found in plasma of children in normal or reduced Se state.During administration of yeast rich in Se (200g Se/d) for 90 days 2 healthy adults showed no significant change of plasma GSHPx activity. During Se supplementation (75–100g Se/d) for 120–163 days 5 dietetically treated patients with PKU or MSUD exhibited a significant increase of plasma GSHPx activity within 2 days. The values reached a plateau after 1 to 3 weeks of supplementation and remained at this level within the following 4 to 5 months. Therefore, the activity of plasma glutathione peroxidase can be used as an indicator of short-term changes of selenium intake in selenium deficient individuals.Abbreviations (PKU) Phenylketonuria - (MSUD) maple-syrup-urine disease - (GSHPx) glutathione peroxidase - (t-BOOH) t-butyl hydroperoxide - (COOH) cumene hydroperoxide - (H₂O₂) hydrogen peroxide - (GSH) reduced glutathione With support of the Deutsche Forschungsgemeinschaft     

Nutritional bioavailability to rats of selenium in Brazil nuts and mushrooms

Weanling male rats were fed a selentum (Se)-deficient Torula yeast diet for 4 to 9 weeks followed by either continued depletion or repletion for 4 to 6 weeks with Se as sodium selenite, extracted Brazil nut meal, or dried mushroom powder. The Se in the Brazil nut meal (Bertholletia excelsa) was fully as available as that in sodium selenite when judged by the ability of dietary Se to restore plasma and liver glutathione peroxidase activities or Se levels. By these same criteria, the Se in cultivated commercial mushrooms (Agaricus bisporus) or wild mushrooms (Boletus edulis) was of very poor bioavailability. Addition of mushroom powder to a diet containing selenite did not interfere with the ability of the selenite to restore hepatic glutathione peroxidase activity during repletion. These results demonstrate the great differences that can occur in the bioavailability of Se from different foods and point out the need to develop suitable Se bioavailability assays in humans.     

Acute toxicity of inorganic selenium to Daphnia magna (Straus) and the effect of sub-acute exposure upon growth and reproduction

The acute toxicities of sodium selenite (Na₂SeO₃) and sodium selenate (Na₂SeO₄) to Daphnia magna were determined in defined culture at 22°C. For adults, the 48-h LC₅₀ values were 0.68 ppm selenium as selenite and 0.75 ppm selenium as selenate. Juveniles were more sensitive, with a 48-h LC₅₀ of 0.55 ppm selenium as selenate. Eggs and embryos were found to be much less sensitive, with a 72-h LC₅₀ of 1.4 ppm selenium as selenate.

Sub-acute exposure of D. magna to sodium selenate caused suppression of growth over instars 1–5 and reduced egg production in instar 9 when adults were exposed to test solutions from instar 6 onwards. These sublethal effects were found at concentrations in the range proposed as suitable for the use of selenium in the amelioration of mercury contamination.     

Effect of selenium on blood pressure,urinary sodium excretion and plasma aldosterone in cadmium-treated male rats

The present study was carried out to help elucidate the possible mechanisms underlying the effect of Cd and the interaction of Se with Cd on blood pressure. Male Wistar rats were divided into four groups: control, Cd-treated, Se-treated, Se-and Cd-treated. Cd and Se were administered at doses of 1.0 mg/kg body weight by subcutaneous injection of aqueous solutions of CdCl₂·2×1/2 H₂O and Na₂SeO₃, respectively. Injections were made either alone or in the Cd+Se treated group, simultaneously at 12–h intervals for 7 consecutive days. All animals were then maintained without further treatment for an additional period of 18 days. Treatment with Cd and Se separately lowered the blood pressure on days 3 and 8, but these levels increased and were significantly higher than that in control rats by day 26. Plasma aldosterone concentrations increased and urinary Na excretion decreased from day 1 to 3 in rats treated with Cd and Se separately. Thereafter, increased water retention precedes the onset of increased blood pressure. From these findings, we suggest that in rats treated with Cd and Se separately the increase in plasma aldosterone is a main factor for decreased urinary Na excretion and increased retention of water, and these factors may be associated with an increase in blood pressure. The treatment with Cd and Se simultaneously decreased urinary Na excretion and increased the plasma aldosterone concentration and water retention before the onset of increased blood pressure. These findings suggest that the increase in the blood pressure in these rats might be the result of the same mechanisms as in the rats treated with Cd alone. Se administered simultaneously with Cd ameliorates the Cd-induced decrease in blood pressure on days 3 and 8 but did not ameliorate the Cd-induced increase in blood pressure on day 26. The Cd concentration in the serum of rats treated with Cd and Se simultaneously was markedly higher than that in the serum of rats treated with Cd alone on day 3, suggesting that a Cd–Se complex in serum would be formed. The effect of Se in preventing a Cd-induced decrease in blood pressure may be associated with the formation of a Cd-Se complex in the serum on day 3. On the other hand, after termination of treatment with Cd and Se there was no significant difference in the Cd concentrations in the serum between the rats treated with Cd alone and the rats treated with Cd and Se together. These findings suggest that a Cd–Se complex formed in serum on day 3 might be dissociated by day 26.     

雷达作业部队人体锌,硒状态调查研究

本文对雷达操纵员与非操纵员人体锌、硒状态进行了调查研究。实验结果提示,两组血浆锌、硒含量有显著差别,而头发锌、硒则无明显差别。表明血浆锌、硒反映人体近期营养状况。调查期间正值飞行训练旺季,雷达操纵员低照度作业时间长,机体维生素A、锌、硒代谢增加,暗适应时间延长。故低照度作业部队在注意其维生素A状态外,还应注意锌、硒的补充,才能维持良好的暗适应功能。     

镉对硒引起的离体大鼠肝细胞DNA损伤作用的影响

应用单细胞凝胶电泳研究氯化镉对亚硒酸钠引起的大鼠肝细胞ＤＮＡ损伤作用的影响。结果表明，在８７５μｍｏｌ／Ｌ、１７５０μｍｏｌ／Ｌ、３５００μｍｏｌ／Ｌ的剂量下，亚硒酸钠单独作用时，可引起肝细胞ＤＮＡ损伤。当氯化镉与亚硒酸钠联合作用时，８７５μｍｏｌ／Ｌ的氯化镉对８７５μｍｏｌ／Ｌ、１７５０μｍｏｌ／Ｌ、３５００μｍｏｌ／Ｌ的亚硒酸钠引起的ＤＮＡ损伤存在明显的拮抗作用，而３５００μｍｏｌ／Ｌ的氯化镉对８７５μｍｏｌ／Ｌ、１７５０μｍｏｌ／Ｌ、３５００μｍｏｌ／Ｌ亚硒酸钠引起的ＤＮＡ损伤不但未显示出拮抗作用，反而使得ＤＮＡ损伤程度加重。１７５０μｍｏｌ／Ｌ的氯化镉与１７５０μｍｏｌ／Ｌ的亚硒酸钠联合作用，拮抗作用最为明显。本研究结果提示，在一定剂量条件下，氯化镉对亚硒酸钠引起的大鼠肝细胞ＤＮＡ损伤存在拮抗作用，并与镉和硒的相对剂量有关     

硒对乙醇致大鼠机体损伤的保护作用

目的 :探讨硒对乙醇致体内脂质过氧化的保护作用及机理。方法 :用 3g/kg体重的乙醇给大鼠灌胃 ,同时自由饮用含硒量为 0 .2 5 mg/L 的亚硒酸钠水溶液 ,饲养三个月。结果 :与单给乙醇组比较 ,乙醇 +Se组大鼠组织和血清 MDA含量显著降低 (P均 <0 .0 1) ,GSH- Px、SOD、CAT活性均升高 (P均 <0 .0 5 )。结论 :硒可能通过增加 GSH- Px、SOD、CAT活性从而抑制过量乙醇对机体的损伤     

Plasma lipid peroxides and antioxidants in human septic shock

In order to assess if an oxidant/antioxidant imaalance is involved in human septic shock and its outcome, we measured plasma levels of the lipid peroxides malondialdehyde—as thiobarbituric acid reactive substance—conjugated dienes and fluorescent products, together with the antioxidants alpha-tocopherol, glutathione peroxidase activity and selenium in 12 patients with septic shock and compared them with values of normal controls. At first measurements, malondialdehyde (median 3.9 mol/l; range 2–38.8) and fluorescent products (median 21.2%; range 9.4–134) were elevated (p<0.05), alpha-tocopherol (median 15 mol/l; range 7–25) and selenium (median 0.76 g/ml; range 0.49–1.09) were depressed (p<0.05). Conjugated dienes and glutathione peroxidase activity were in the normal range. In non-survivors (n=5) initial levels of malondialdehyde and fluorescent products (median 11 versus 3.1 mol/l; 74 versus 135 respectively) were higher than in survivors (p<0.05) and initial selenium levels were lower (median 0.58 versus 0.92 g/l;p<0.05). These results are consistent with the concept that an oxidant/antioxidant imbalance—as indicated by elevated plasma lipid peroxides and depressed antioxidants—is involved in human septic shock and a fatal outcome.