Ivan S. Palmer

Identification of a major selenium excretory product in rat urine

Abstract 1. 1. Very few organic metabolites of selenium have been identified from mammalian systems. The objective of this study was to isolate selenium-containing metabolites from rat urine. 2. 2. A new selenium metabolite was isolated from the urine of rats injected with [ 75 Se]selenite. The metabolite was identified as a trimethylselenonium ion. Infrared spectra, nuclear magnetic resonance spectra, cocrystallizaton data and cochromatography data confirm the identity of the metabolite. 3. 3. Substantial amounts of trimethylselenonium ion (30–50% of urinary selenium per 24 h) are excreted after a single injected dose of selenite. It is a normal excretory product of selenite selenium.

Trimethylselenonium ion as a general excretory product from selenium metabolism in the rat

Abstract 1. 1. Several sources of selenium were given to rats and the metabolites excreted in the urine were examined chromatographically. 2. 2. A recently identified product of selenite metabolism, (CH 3 ) 3 Se + , was shown to be a major excretory product from selenate, selenomethionine, selenocystine, Se- methylselenocysteine, and seleniferous wheat. The level of (CH 3 ) 3 ) 3 Se + in the urine was equivalent ot 20–50% of the urinary selenium depending on the selenium source and the collection time. 3. 3. A second major unidentified urinary metabolite was excreted from each radioactive selenium source and accounted for 11–28% of the total urinary selenium. 4. 4. On the basis of chromatographic evidence, the selenium-containing metabolites in rat urine seem to be familiar regardless of the original source of selenium.

Toxicity of trimethylselenonium chloride in the rat with and without arsenite

Abstract Trimethylselenonium chloride (TMSeCl) was submitted to a toxicologic evaluation in rats. The ip LD50 was 49.4 mg Se/kg. In the presence of 4 mg of As/kg injected as arsenite, the LD50 was reduced to 2–3 mg Se/kg. The toxicity of trimethylsulfonium iodide was similar to that for TMSeCl, but arsenite had no effect. To further examine the apparent synergism between arsenite and TMSeCl, the effect of arsenic on the elimination of TMSe-selenium in the breath and in the urine was studied. At different levels of selenium administration, 3–9% was exhaled, and this amount was increased by the injection of arsenite. On the other hand, arsenite injection reduced urinary selenium excretion. It was also found that arsenite and dimethyl selenide (DMSe) were more toxic in combination than when injected individually, but arsenite did not affect the exhalation of Se from DMSe. When TMSeCl was fed, levels above 240 ppm Se were required to reduce growth, and even at a level of 960 ppm Se, no deaths were observed in a 5-wk experimental period. The presence of arsenite in the diet slightly increased the toxicity of the TMSeCl administered in the diet at intermediate levels of selenium.

Selenoamino acids in tissues of rats administered inorganic selenium.

There are conflicting reports in the literature concerning the synthesis of selenoamino acids from inorganic selenium in animals, and this work was undertaken to further investigate this. Pronase digests of acetone powders of liver and kidney tissue from rats administered 75SeO3= were subjected to fractionation by cation exchange chromatography using current methods for separating the various amino acids. Very little, if any, selenocystine was found in the digests. However, good evidence was obtained for the occurrence of 2,7-diamino-4-thia-5-selenaoctanedioic acid. It is suggested that the selenocysteine portion of this compound was formed by the reduction of the selenite to selenide with its subsequent incorporation into the amino acid by the action of serine hydrolase (E C 4.2.1.22). No selenomethionine was found under the conditions of this study.

Selenoprotein levels in patients with colorectal adenomas and cancer.

OBJECTIVES:Selenium is a trace mineral that, as a constituent of certain selenoproteins, acts as an antioxidant. Results of studies addressing a cancer protective effect of selenium have been controversial. The present study measured selenoprotein-P, extracellular glutathione peroxidase, and plasma selenium in patients with colon cancer and adenomatous colon polyps to determine whether patients who develop colorectal adenomas or cancer are selenium deficient.METHODS:Patients who presented to an endoscopy center for colonoscopy or who were referred to our institution with a newly diagnosed colorectal cancer were offered enrollment in the trial. Each patient underwent phlebotomy, usually immediately after colonoscopy. In all, 103 patients were enrolled in the study. Of these, 33 patients were found to have colorectal cancer, 35 adenomatous colon polyps, and 17 normal examinations. A total of 18 patients had other diagnoses and were not included in the study group.RESULTS:The mean age for the colorectal cancer group was 69 yr, for the adenomatous colon polyp group 62 yr, and for the normal group was 56 yr. The adenomatous colon polyp and normal groups were predominantly female. Based on one way analysis of variance tests, there was no significant difference in selenoprotein-P or plasma selenium levels or extracellular glutathione peroxidase activity among the three groups (p = 0.28, 0.098, and 0.35 respectively).CONCLUSIONS:The present data suggest that patients with adenomatous colon polyps and those with colorectal cancer are not selenium deficient.

Distribution of Serum Selenium, Copper, and Zinc in Normal Human Pregnancy

The distribution of the serum levels of selenium, zinc, and copper in human pregnancy at various gestational ages were determined from two ethnically and geographically different populations (Rosebud Indian Reservation and southeastern South Dakota) of 410 normal subjects. As gestation age increased, there was a significant increase and a slight decrease in the mean levels of copper and zinc, respectively. No change in the levels of selenium was observed. Significantly higher levels of both pregnancy and non-pregnancy serum copper were observed in the Rosebud population compared to that in southeastern South Dakota, possibly due to the significantly higher level of copper in the Rosebud water. No differences were observed in the zinc or selenium levels between the two populations. Serial measurements of these trace metals during the third trimester of pregnancy were performed on 18 subjects, and supported the trends described for copper and selenium. No decrease in zinc was observed in the individual subjects.

Effect of source of calcium and phosphate, autoclaving, vitamin D3 level and strain of turkey poults on the rachitogenic activity of isolated soybean protein 1

Synopsis This study was conducted to ascertain the effect of autoclaving, source of calcium and phosphate, vitamin D3 level and strain of turkey poults on the rachitogenic activity of isolated soybean protein (C‐1 protein‐Skidmore). One‐day‐old poults were fed purified diets of the glucose—C‐1 protein type. The diets contained calcium, phosphorus and vitamin D3 at levels equal to or greater than the National Research Councils (1960) recommendations. The findings demonstrate that USP hydrated dicalcium phosphate was more effective than food‐grade dicalcium phosphate in overcoming the rachitogenic activity of the C‐1 protein. Autoclaving the C‐1 protein for 80 min destroyed its rachitogenic activity: Vitamin D3 was also effective in reducing the rachitogenic effect of C‐1 protein. The Broad Breasted White strain proved to be more susceptible to the rachitogenic property of C‐1 protein than the Wrolstad Small White strain. Substituting USP hydrated dicalcium phosphate for food‐grade dicalcium phosphate, aut...