Ppm Selenium Research Articles

Selenium deficiency and protein, RNA and DNA synthesis in rat pancreas and liver.

SummaryRats on a selenium-deficient torula yeast diet containing 100 mg Vitamin E/kg compared to a similar diet with 0.5 ppm selenium as sodium selenite do not show any decrease in protein, RNA and DNA synthesis in the pancreas or liver. The gross depression and change of pancreatic enzymes found in the chick on selenium-deficient diet were not apparent in the rat on a selenium-deficient diet.

Effect of cystine, selenium, and fish protein on the toxicity and metabolism of methylmercury in rats

Investigations were made of the effect of 0.4% cystine, 0.6 ppm selenium, and fish protein on the toxicity and metabolism of mercury from methylmercuric chloride in male and female weanling rats. When diets with 10% protein and adequate amounts of other nutrients contained 25 ppm mercury, cystine reduced toxicity, selenium as sodium selenite had a greater effect in reducing toxicity, and the combination of cystine and selenium produced a considerably greater additive effect, as measured by increased growth and survival time. Toxicity signs were reduced when fish protein replaced casein in the basal diet, and a 20% protein level from either source reduced toxicity symptoms as compared to a 10% protein level. Cystine, selenium, and fish protein did not inhibit mercury toxicity by increasing its elimination from the body via the urine and feces and, in fact, slightly more mercury was retained when cystine and selenium were added to diets. Few differences were found in the deposition of mercury in tissues that could be attributed to cystine, selenium, and fish protein. The major difference found was in one experiment in which mercury concentrations in the kidney were considerably lower when diets contained cystine, selenium, and fish protein. Possible explanations for the effects observed in these studies included a reduction in mercury accumulation and, hence, damage in the kidney, complexing of mercury by the additives evaluated, and conversion of organic mercury to the less toxic inorganic form.

Response of Glutathione Peroxidase to Dietary Selenium in Rats

The effect of dietary selenomethionine on the enzyme activities of the glutathione (GSH) peroxicla.se system in rat tissues was studied. The activity of GSH peroxidase decreased to varying degrees in tissues from animals fed a basal low selenium Tonila yeast diet for 17 days. The relative decrease was plasma > kidney, heart, liver and lung > erythrocytes > testes. The activity of GSH peroxidase in all tissues except testes was significantly and linearly increased above that of the nonsupplemented controls when selenium-depleted animals were subsequently fed the same diet supplemented with 2 ppm selenium for 11 days. The relative increase was plasma > kidney > heart, erythrocytes, lung, and liver > testes. Dietary selenium did not significantly alter the activities of GSH reductase and glueose-6-phosphate (G-6-P) dehydrogenase. Intra- peritoneal administration of actinomycin D or puromycin neither effectively suppressed the increase of GSH peroxidase activity nor inhibited the activities of GSH reductase and G-6-P dehydrogenase; however, it is possible that insufficient dosages were ad ministered. In vitro studies with tissue soluble fractions and plasma from rats fed diets with low or high selenium levels suggest that selenium is not an exchangeable or a dialyzable cofactor for GSH peroxidase. These studies provide further evidence of the essentiality of selenium for the activity of GSH peroxidase. J. Nutr. 104: 444-451,

Biological potency of organic selenium compounds V. diselenides of alcohols and amines, and some selenium–containing ketones

The diselenides of straight-chain aliphatic alcohols with 2 to 4 carbon atoms, and the acetic acid ester of the C 5 homolog were similar in potency to the corresponding carboxylic acids in protecting against dietary liver necrosis in the rat. As in carboxylic acids, substitution of a methyl group at the carbon atom adjacent to the selenium atom diminished activity, but a methyl group in the β position had no such effect. Two methyl groups in the β position, producing a quaternary carbon atom, abolished biological activity, as seen in other series of compounds. Diselenides of aliphatic and heterocyclic amines showed low biological activity. 3-Aminopropyl diselenide was half as active and dimethyl and diethyl amino derivatives with C 2 and C 3 carbon chains only approximately 1/10th as active as selenite. N-piperidyl and N-morpholinyl derivatives with C 2 and C 3 carbon chains also showed low activity. Monoseleno-ketones, on the other hand, with ketone oxygen in the β or γ position to the selenium atom showed good activity, indicating an enhancing effect of the ketone oxygen on the biological availability of the selenium atom. The dimethylacetal of benzylseleno-acetaldehyde afforded 50% protection at a level of 1.1 μg% selenium (0.011 ppm selenium) in the diet, i.e., it was twice as active as selenite selenium or the corresponding benzylselenocarboxylic acid.

EFFECTS OF SELENIUM SUPPLEMENTATION OF NATURALLY HIGH SELENIUM SWINE RATIONS ON TISSUE LEVELS OF THE ELEMENT

An experiment was conducted, using high selenium Record of Performance (ROP) test rations (0.46 and 0.78 ppm selenium), to study the effects of dietary supplementation with 0.1 ppm selenium (sodium selenate) on residues of the element in porcine tissues. Treatments included no selenium supplementation, selenium supplementation of the starter ration from 16 kg to 23 kg (average body weight), addition of selenium to both the starter and grower-finisher rations up to 57 kg, and dietary selenium supplementation for the entire starter-grower-finisher period. None of the treatments had any effects on the selenium content of kidney, liver, heart, blood, or loin, shoulder, and ham muscles, as compared with unsupplemented controls. The significance of the results is discussed in relation to differences in retention of natural dietary selenium and supplemental inorganic forms of selenium and likely effect of selenium supplementation of swine rations on selenium levels in the human diet.

Selenium supplementation of naturally high selenium diets for swine.

Two trials were conducted (one at Michigan State University and a second at South Dakota State University) involving supplementation of naturally high selenium swine diets (0.24 to 0.45 ppm) with 0.1 ppm of selenium from sodium selenite. In one trial, a low selenium diet (0.04 ppm) was supplemented with 0.40 ppm of selenium from sodium selenite to supply total selenium levels comparable to a naturally high selenium diet. Sodium selenite additions to the naturally high selenium diets did not significantly increase longissimus muscle or kidney selenium concentrations and increased liver selenium concentrations only slightly. Tissue selenium levels resulting from adding 0.40 ppm of selenium from sodium selenite to a naturally low selenium diet (0.04 ppm) were significantly lower than when a naturally high selenium diet (0.44 ppm) was fed. It appears that the dietary level of naturally-occurring organic selenium compounds is much more significant in influencing the tissue selenium concentration of the pig than supplemental selenium from sodium selenite.

Effect of dietary selenium level on Se binding to rat plasma proteins.

SummaryTwo peaks of protein-bound 75Se are seen on the gel filtration chromatogram of rat plasma when the rat has been fed a 0.5 ppm selenium diet and no NaCl is added to the Tris-HCl elution buffer. One of those peaks is absent from the plasma of rats fed a very low selenium diet. Poly-acrylamide gel electrophoresis of the 75Se peaks suggests that each may have more than one protein component. Dialysis studies indicate that the 75Se is not in the form of selenotrisulfides.

Studies on Selenium Related Compounds. I. The Determination of Selenium by Gas Chromatography

As a hygienic chemical study on the treatment and on the influence of selenium to humans, microdetermination of selenium in various kinds of sample was investigated. Selenium (IV) in the sample was converted to selenium (IV) by heating in hydrochloric acid of concentration above 17%. Treatment of selenium (IV) by heating in hydrochloric acid of concentration above 17%. Treatment of selenium (IV) with 4-chloro-o-phenylenediamine at pH 1 in a boiling water-bath gave 5-chloropiaselenol quantitatively. 5-Chloropiaselenol thus obtained was extracted with benzene at pH 1 and determined by ECD gas charomatography with 15% OV-17 Chromosorb W. High sensitivity of this method enables determination of 0.05 ppm of selenium and the calibration curve is linear up to 0.8 ppm. This microdetermination method is considered to be applicable to various kinds of samples such as river water, food, and animal tissues.

Enhancement of Sensitivity for Selenium Determination in Atomic Absorption Spectrophotometry by Introducting Hydrogen Selenide into an Argon-Hydrogen Flame

Abstract The sensitivity for selenium determination with atomic absorption spectrophotometry is enhanced to a large extent by introducing hydrogen selenide gas into an argon-hydrogen flame. As a reducing agent, zinc granular and stannous chloride is successfully used for quantitative and rapid productions of hydrogen selenide from selenium(IV) solution. The sensitivity for 1 % absorption of the signal is estimated to be about 0.02 ppm of selenium.

Selenium and tellurium in mice. Effects on growth, survival, and tumors.

In order to ascertain innate toxicities of selenium and tellurium, 427 mice were given selenite, selenate, tellurite, and tellurate in drinking water for life, at 3 ppm selenium and 2 ppm tellurium, in an environment controlled as to contaminating trace elements. There were 209 controls. No signs of toxic effects in terms of growth, survival, or longevity appeared in males. Selenite-fed males were heavier and females were lighter than their controls at various ages, and female longevity was decreased. No toxic effects were observed in the groups fed tellurate, but in females fed tellurite longevity was decreased. Selenium level was increased in tissues when selenium was fed. None of the four compounds affected the incidence of spontaneous tumors significantly. Amyloidosis occurred more frequently in mice fed selenium than in controls or those fed tellurium.

A Volcanic Origin for the No. 5 Zone of the Horne Mine, Noranda, Quebec

The No. 5 Zone of the Horne Mine in the Noranda District consists of massive to disseminated sulfides, mainly pyrite, enclosed conformably within steeply dipping, interbedded tuffs, rhyolite tuff breccias, and rhyolite breccias of Archean age. Large sulfide masses are elongate down dip and have oval to roughly tabular cross sections. They are closely spaced and overlapping, due apparently to successive submarine slumping of soft, unconsolidated sulfide masses and rhyolitic pyroclastics on the flanks of a volcano. Textures of the sulfides suggest that they underwent subsequent dynamic and regional metamorphism probably during the Kenoran orogeny (2.5 billion years).Pyrite in the No. 5 Zone contains 12-60 ppm cobalt and 33-88 ppm selenium, whereas that in the adjacent economic H ore bodies contains about 1,000 ppm cobalt and 390-1,000 ppm selenium. These differences suggest an independent formation of the No. 5 Zone.Large fragments of sulfides similar in composition and texture to the sulfides in the massive bodies of the No. 5 Zone occur in the overlying breccias and were apparently derived from the No. 5 Zone during periods of explosive volcanism. The massive sulfides therefore must have formed during the same period of volcanism.

Selenium and Tellurium in Rats: Effect on Growth, Survival and Tumors

To evaluate the innate toxic effects of selenate, selenite and tellurite, 313 rats were given 2 ppm selenium or tellurium as these compounds in drinking water from the time of weaning until natural death, in a controlled environment. There were 105 controls. After 1 year, the doses of selenium were increased to 3 ppm. Selenite was extremely toxic, suppressing growth and causing high early mortality in males but less in females; the experiments were ended at 20 to 23 months. Selenate and tellurite were not toxic in terms of growth, survival and longevity. Selenium accumulated in five organs of control rats, although the diet contained only 0.05 µg/g wet weight; concentrations were more than doubled in selenium-fed animals, with kidney having the most. Fasting serum glucose levels were higher than controls in older selenium- and tellurium-fed males and in younger tellurium-fed females, without excess glycosuria. Fasting serum cholesterol levels were higher than the controls in selenium- and tellurium-fed rats of both sexes, and aortic lipids were considerably increased. In older animals, selenate was both tumorigenic and carcinogenic, whereas tellurite was not, there being 16.9% malignant tumors in the controls, 41.7% in the selenate and 18.2% in the tellurite groups.

Toxic effects of trace elements on the reproduction of mice and rats.

Breeding mice and rats were exposed to low doses of six trace elements in drinking water in an environment controlled as to contaminating trace metals. Each group was carried through three generations. Compared to control mice given only doubly deionized wafer, selenafe (3 ppm selenium) resulted in excess deaths before weaning, runts, and failures to breed. Lead (25 ppm) and cadmium (10 ppm) resulted in loss of the strain in two generations with many abnormalities. Molybdate (10 ppm molybdenum) was slightly toxic in this respect, and arsenic resulted only in elevated ratios of males to females. In rats, lead was very toxic, and titanium and nickel moderately toxic, resulting in many early deaths and runts. This method provides fairly rapid estimates of innate toxicities of trace elements in doses tolerable for growth and survival.

Growth, Reproduction, and Tissue Concentrations of Selenium in the Selenium-depleted Rat

Selenium-depleted rats were obtained by feeding a purified low selenium amino acid diet to commercially available weanling rats or by breeding females maintained on a Torula yeast diet. Both diets were fortified with dl-a- tocopherol. Selenium concentrations in blood, liver and skeletal muscle of wean ling rats obtained commercially and fed the purified diet decreased from initial values of 0.32, 0.60, and 0.23 ppm to 0.05, 0.04, and 0.02 ppm, respectively, in 20 weeks. Seventy percent of these declines occurred in the first 6 weeks. Supple mentation of the purified diet with 0.5 ppm selenium in selenomethionine im proved growth and produced increases in blood and liver selenium for 20 weeks but skeletal muscle selenium remained constant. Second and third litters of females fed the Torula diet were hairless at weaning and had blood concentra tions below 0.07 ppm. Second and third litter offspring of these depleted dams showed improved body and hair growth when fed the diet of their dams supple mented with 0.50 ppm selenium as selenomethionine. The females maintained for 6 months on the Torula yeast reproduced normally through three Utters. Their blood selenium values decreased from 0.52 to 0.06 ppm during this time. Affirma tive evidence is presented that selenium is a required nutrient, and regimens for producing selenium-depleted animals are discussed. J. Nutr. 101: 761-766, 1971.

Interactions of Methionine, Vitamin E, and Antioxidants in Selenium Toxicity in the Rat1

Female Wistar albino rats were fed a low vitamin E diet based on peanut meal and containing 10 ppm selenium as Na2SeO4. Supplementation of the diet with either 0.5% dl-methionine (Met) or 0.05% dl-α-tocopheryl acetate (E) alone gave little protection against the liver damage due to selenium. However, a combination of 0.5% Met plus 0.01 to 0.05% E gave increasingly better protection depending on the level of E added. Combinations of 0.5% Met plus 0.05% N,N′-diphenyl-p-phenylenediamine, 1,2-dihydro-6-ethoxy-2,2,4-trimethylquinoline, or butylated hydroxytoluene were also effective against liver damage, whereas supplements of 0.5% Met plus 0.1% disodium ethylenediaminetetraacetate, 0.25% methylene blue, or 0.5% ascorbic acid gave little or variable protection against selenium. Replacement of the 0.5% Met with equimolar amounts of cysteine, betaine, or cysteine plus betaine gave variable results. Addition of 0.39% guanidoacetic acid to a diet supplemented with 0.5% Met and 0.05% E appeared to inhibit the protective effect of the Met-E combination. Selenium levels in the livers and kidneys of rats fed supplements which protected against selenium poisoning were lower than those of the animals fed the unsupplemented seleniferous peanut meal diet. It is suggested that vitamin E and the fat-soluble antioxidants make the methyl group of methionine more available for selenium detoxification.

Selenium Concentrations in Forage on Some High Northwestern Ranges

Forages produced on some high northwestern ranges were analyzed for selenium concentration to determine the hazard of white muscle disease (WMD) in calves and lambs. The selenium concentration in 94 forage samples ranged from 0.01 to 0.78 ppm, of which 20 samples contained more than 0.10 ppm. The remaining 74 samples contained less than 0.10 ppm and 59 of those contained Less than 0.05 ppm. Approximately 90% of the summer ranges studied produce forage containing less than 0.10 ppm selenium. Thus, the hazard of WMD on these northwestern ranges may be high. Ranchers should work individually and in groups to ascertain losses from the disease and minimize them by injecting the animals with selenium.

Ultraviolet Spectrophotometric Determination of Selenium by 1-Pyrrolidinecarbodithioate Method

Abstract An ultraviolet spectrophotometric method for the determination of selenium has been developed using ammonium 1-pyrrolidinecarbo-dithioate. The selenium(IV)-1-pyrrolidinecarbodithioate complex is extracted with chloroform and the absorbance of the extract measured at 303 mμ. Conformity to Beer's law was found for 0.5 to 9 ppm of selenium.

Some Selenium Responses in the Rat not Related to Vitamin E

Rats fed a low selenium ration containing Torula yeast with adequate vitamin E grew and reproduced normally. Their offspring were almost hairless, grew more slowly and failed to reproduce. Supplemental dl-methionine, sodium sulfate, or increased dosage of vitamins was without effect. Supplementing with 0.1 ppm selenium as sodium selenite restored haircoat, growth, and reproductive capabilities. Some usual biochemical tests for selenium or vitamin E deficiency status, or both, were inconclusive when compared with rats fed normal rations. Rats fed low selenium corn protein also had sparse hair and poor growth in the second generation. A low selenium ration from ewe muscle, however, supported rats for three generations without any abnormalities.

Tissue fatty acids in normal and myopathic lbs.

In the 16 weeks prior to lambing, ewes were maintained on either 0.01 or 0.40 ppm selenium alfalfa forage of similar lipid composition supplemented with ground oats. Lambs were necropsied (53 tissue samples) at 6 weeks of age for evidence of WMD, a selenium responsive myopathy. Heart and semitendinosus muscle from affected animals had an elevated level of endogenous fatty acids and a decrease in ω6 and ω3 classes. There were no significant changes within the endogenous class of fatty acids. In the ω6 class the relative percentage of 18:2 fatty acid was increased in heart tissue with WMD. Values in the ω6 and ω3 class of the semitendinosus muscle showed no trend with WMD. In the ω3 class, the heart fatty acid distribution suggests that selenium may be involved in the synthesis of the higher molecular weight members of the class. Liver and kidney fatty acids were not indicative of WMD.

INFLUENCE OF SELENIUM ON THE ABSORPTION, EXCRETION AND PLASMA LEVEL OF TRITIUM-LABELLED VITAMIN E IN THE RAT

In two experiments the influence of selenium supplementation of a basal diet low in both selenium and vitamin E on the absorption, excretion, and blood distribution of a single dose of tritium-labelled α-tocopherol in rats was examined. Urinary and fecal excretion of radioactivity was determined at 24-hour intervals over a three-day period. In experiment 1, supplementation with 0.5, 1.0 or 2.0 ppm selenium had no significant effect on the absorption or urinary excretion of the radioactivity. In the second experiment, supplementation with 2.0 ppm selenium again had no significant effect on absorption or excretion of the labelled tocopherol. A group receiving dietary supplementation of 500 IU vitamin E per kg diet excreted significantly more of the dose in the urine (P < 0.01) and in the feces (P < 0.05) than did the basal group. The plasma level of radioactivity was significantly lower (P < 0.01) in the selenium-supplemented group than in the basal animals. Chemical determination of the plasma α-tocopherol level similarly indicated lower values in the selenium-supplemented animals. These results suggested a possible role for selenium in promoting the withdrawal of vitamin E from the blood by the tissues. Levels of radioactivity were higher in the heart and liver tissue of the selenium-supplemented animals, but the differences were not statistically significant (P > 0.05). In the rat, selenium does not appear to influence the absorption or retention of vitamin E, but does affect the plasma vitamin E level and may modify its distribution in the tissues.