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At least 109 records · Page 6Linked to original sources
PubMed1975

Modification of a selenium toxicity in chicks by dietary silver and copper.

Studies were conducted to determine the effects of high levels of dietary silver nitrate and copper sulfate on the response of chicks to toxic levels of dietary selenium. Adding 5 ppm or more selenium to a basal stock diet significantly reduced growth rate, and 40 ppm or high significantly increased mortality during the 2-week experiments. Deitary silver or copper (1,000 ppm) counteracted the growth depression and prevented mortality at the higher levels of selenium. Hepatic selenium reached a maxiumum in chicks fed the basal diet with 10 ppm dietary selenium. Hepatic selenium of chicks fed silver was less than that of the control chicks when diets containing 10 ppm or less selenium were fed. Adding copper to the diet resulted in considerable accumulation of selenium in the liver, which was evident even at the lower levels of added selenium. Rseults of an experiment to determine the effects of deitray silver and copper on the distribution of 75-Se administered either orally or in tramusculary showed that silver interfered with absorption of selenium. The results of these experiments suggest that silver modifies selenium toxity both by interfering with selenium absorption and by causing the accumulation of a nondeleterious selenium compound in the tissues. Copper modifies selenium toxicity primarily by causing the accumulation of a nondeleterious compound in the tissues.

Administration, Oral↗
PubMed1984

Measurement of trimethylselenonium ion in human urine.

A comparison is made between two methods (ion-exchange chromatography vs a difference method) for the quantitative measurement of trimethylselenonium ion (TMSe) in human urine. It is shown that the difference method yields reliable data only if TMSe constitutes a relatively large fraction of urine selenium. Under normal conditions of selenium intake in man, accurate measurement of this important metabolite can, at present, be carried out only with the ion-exchange chromatographic procedure. Preliminary data from a human subject employing stable isotope tracer methodology are given to show that the fraction of urine selenium present as TMSe varies with the level of intake as well as other factors.

Chemical Phenomena↗
PubMed1985

Erythrocyte selenium-75 uptake as a measure of selenium status in weaner sheep, and its relationship to erythrocyte glutathione peroxidase activity.

The relationship between in vitro erythrocyte 75Se uptake (75Se uptake) and erythrocyte glutathione peroxidase (EGSHPx) activity was examined in weaner sheep during periods of selenium depletion and repletion, to determine whether 75Se uptake was better correlated than EGSHPx activity to the development of weaner nutritional myopathy. In the 2 trials conducted, only 3 of 45 Merino wether weaners developed clinical myopathy and histological lesions in skeletal muscles. The 75Se uptake values and EGSHPx activities in these 3 sheep were no different from those in the unaffected sheep. There was a significant negative correlation between 75Se uptake values and EGSHPx activities over the entire period of the trials. It could not be demonstrated that 75Se uptake was any better correlated than EGSHPx activity to the development of nutritional myopathy, and it was concluded that EGSHPx activity indicated selenium status better than 75Se uptake in weaner sheep.

Animals↗
PubMed1962

Intestinal transport of selenium-75 selenomethionine.

When measured simultaneously, selenium-75 selenomethionine accumulated identically with sulfur-35 methionine across everted hamster intestinal sacs in the presence of carrier methionine. The apparent K(m) for L-methionine transport was 0.8 x 10(-3) M, as calculated from the beta emissions of S(35)-methionine or the gamma emissions of Se(75)-selenomethionine. Absorption of Se(75)-selenomethionine from the gastrointestinal tract of man also occurred, with peak blood levels being reached in about 3 hours. Because of the 122-day half-life of selenium-75 and its multiple gamma emissions, Se(75)-selenomethionine may serve as a tool in evaluating amino-acid absorption.

Amino Acids↗
PubMed1978

In vitro studies on interaction of mercuric mercury and selenite in rabbit blood.

The behaviors of inorganic mercury and selenite in rabbit blood, added in vitro individually or in combination, were investigated. Inorganic mercury incorporated into erythrocyte in the absence of selenite was mainly present in the fractions which were eluted from Sephadex G-200 column just after hemoglobin. On the other hand selenium incorporated into erythrocyte in the absence of mercury was eluted in hemoglobin fractions and also in those which are almost completely retained by the column. In the combination experiment, however, the incorporation of mercury and selenium was remarkably enhanced and the increased amounts of both the compounds were eluted together with each other around the void volume region of the Sephadex G-200 column. The existing state of mercury and selenium in the high-molecular weight fractions and the effects of some metabolic inhibitors on the behavior of these compounds in blood were also studied.

Animals↗
PubMed1984

Metabolism of [75Se]selenite by rhesus monkeys.

The metabolism of [75Se]selenite was studied in rhesus monkeys. In blood samples taken various times after injection, Sephadex G-150 gel filtration revealed that the majority of the 75Se was associated with hemoglobin and low-molecular-weight compounds in erythrocytes up to 24 hours after selenium injection. Subsequently a gradual increase of 75Se occurred in glutathione peroxidase (GSH-Px) with a concurrent decrease of label with hemoglobin. In contrast to the erythrocytes, over 80% of the labeled selenium in plasma was associated with one peak 3 hours and later after injection. This major protein eluted at a position similar to GSH-Px on gel filtration, but subsequent chromatography on diethylaminoethyl (DEAE)-Sephacel separated the radiolabeled protein from GSH-Px. Gel filtration of heart, muscle, brain and pancreas cytosol revealed two major selenium-containing proteins, whereas one was predominant in liver and kidney. The major selenium peak was associated with GSH-Px in liver but not in the kidney. GSH-Px activity with either organic or inorganic peroxides as substrates and glutathione transferase activity were higher in liver than kidney.

Animals↗
PubMed1979

[Tropism of radiopharmacologic preparations in lymphogramulomatosis in mice].

In experiments on 75 female mice of line SJL/J with lymphograulomatosis, 75 female mice of the same line without lymphogranulomatosis and intact non-lineal mice, the authors have studied the labelled tumorigenic compounds: indium-111, gallium-67-citrates and sodium selenium-75-selenite. It was found that only sodium selenium-75-selenite possesses an enhanced ability to be accumulated in lymphogranulomatosis involved lymph nodes in mice. Whereas indium-111 and gallium-67-citrates contrary to the literature data available showed no enhanced tropism to lymph nodes of mice with lymphogranulomatosis.

Animals↗
PubMed1972

Effects of selenium compounds on formate metabolism and coincidence of selenium-75 incorporation and formic dehydrogenase activity in cell-free preparations of Escherichia coli.

The effects of selenite, selenocystine, and selenomethionine in a defined growth medium on formic dehydrogenase biosynthesis in aerobically and anaerobically grown Escherichia coli have been studied. Sucrose gradient centrifugation of a partially purified enzyme demonstrated a coincidence of (75)Se incorporation and formic dehydrogenase activity.

Aerobiosis↗
PubMed1982

[A new correction method for radionuclide formation in neutron activation analysis using a reactor power meter coupled with a microcomputer].

Neutron flux and irradiation time should be accurately known in neutron activation analysis using very short lived nuclides in which conventional monitoring methods i.e., a comparator method, flux monitor method and so on cannot be used satisfactorily. Especially, fluctuation of neutron flux has not been corrected. We noted a change of reactor power at a pneumatic operation, and found out a new correction method for its correction in activation analysis. In our small nuclear reactor, TRIGA-II, the reactor power increased rapidly a few % when a pneumatic-operated capsule arrived at a core of the reactor, and decreased when the capsule left from the core. If the duration between these two changes of the reactor power is equal to the irradiation time, and that the reactor power is proportional to the neutron flux, we can regard an activity formation as a time integration of the reactor power. Then, the correction system was made of a reactor power meter, a V-F converter (voltage to frequency converter), a clock time, a counter, a microcomputer, electric circuits and so on. The signal of the reactor power during the irradiation was counted through the V-F converter, and was accumulated in a memory of the microcomputer. The neutron fluence was calculated in this microcomputer. This method was examined by means of activation of copper and selenium standard samples by 9-11 sec irradiations. The observed activity involved +/- 10% error. However, the error in the corrected activity was decreased to a few % using this correction method. As a result, we found that this method can be used to obtain accurate value for radionuclide formation.

Activation Analysis↗
PubMed1986

Syntheses of selenium labelled compounds--II. The exchange reaction with elemental selenium.

73Se labelled 2-selenouracil was prepared by the isotope exchange reaction method. It has been well known that in order to prepare labelled compounds in high specific activity by exchange reaction, the substrate compounds have to be used in small quantities. For 2-selenouracil, however, the reaction in low concentration is not always preferable for the labelling of high specific activity within a limited time. The optimum conditions for the preparation of [2-73Se]-2-selenouracil of maximum specific activity were determined.

Humans↗