Liver Selenium Concentrations Research Articles

Mercury, cadmium, zinc, copper and selenium in harbour porpoise (Phocoena phocoena) from West Greenland

Muscle, liver, kidney and skin samples taken from 78 harbour porpoises (Phocoena phocoena) were analysed for mercury, cadmium, zinc, copper and selenium. The highest concentrations of mercury were found in the liver (geometric mean 4.17 μg/g wet weight), whilst the highest concentrations of cadmium were in the kidney (g.m. 13.2 μg/g ww). The levels of cadmium were more than ten times higher than in harbour porpoises from the North Sea and the British NW coast, whilst the mercury levels were about the same. The importance of the cadmium content in the prey is discussed, but this attempt did not revealed the differences. Very high levels of zinc (g.m. 359 μg/g ww) and selenium (g.m. 28.6 μg/g ww) were found in skin samples, respectively seven and ten times more than in liver. A significant correlation was found between age and the level of mercury and cadmium in all organs. The concentration of mercury and selenium in liver and skin samples and of cadmium and zinc in kidney samples were highly correlated.

Concentrations, Distribution, and Sources of Selenium from Irrigated Lands in Western United States

Concentrations, distribution, and sources of selenium from irrigated lands were studied between 1986 and 1990 at 20 reconnaissance project areas in 17 western states under the Department of Interior's National Irrigation Water Quality Program. Samples of water, bottom sediment, whole‐body fish, and bird livers for analysis of selenium concentrations were collected before, during, and after irrigation season from streams, canals, lakes, and ground water in each project area. Selenium concentrations in water ranged from less than the detection limit of 1 μg/L in 42% of the 586 samples collected to 4,800 μg/L from a well in the Pine River Area, in southern Colorado. Selenium concentrations in 223 samples of bottom sediment ranged from less than the detection limit of 0.1 μg/g to 85 μg/g in a sample from the Middle Green River Basin, in Utah. Selenium concentrations in whole‐body fish (all species) ranged from 0.1 μg to 50 μg per gram dry weight, with the maximum concentration observed in a carp from the Gunnison River Basin, in western Colorado. Selenium concentrations in bird livers (all species) ranged from less than 0.32 μg to 170 μg per gram dry weight with the maximum concentration observed in the liver of an avocet from the Kendrick Reclamation Project, in Wyoming. Cretaceous‐age marine shales probably are the original sources for selenium in 16 of the 20 areas studied. In several areas, evaporative concentration of applied irrigation water and drainage of this water to wetlands, canals, streams, and lakes appears to be responsible for elevated concentrations of selenium.

Improved flow injection analysis (FIA) method for determining selenium in biological samples, and the effect of captopril administration on selenium levels and glutathione peroxidase activity in rat.

An improved flow injection analysis (FIA) method has been developed for the determination of trace selenium in biological samples, and this method has been applied to investigate the effect of captopril, an antihypertensive drug having a thiol group, on selenium concentrations in the rat blood, liver and urine. After oral administration of captopril, selenium levels in the blood decreased, while those in the liver increased significantly. However, no pronounced effect was observed on the urinary excretion rate. The glutathione peroxidase activities in the blood and the liver were comparable to the changes in the selenium levels.

Dietary selenate versus selenite for cattle, sheep, and horses.

Food and Drug Administration regulations currently permit addition of .3 mg of Se per kilogram of diet for chickens, turkeys, ducks, swine, sheep, and cattle. However, field reports indicate that this level may not be adequate for ruminants in all situations. Because sodium selenite is the most common supplemental form and is known to be readily absorbed to particles or reduced to insoluble elemental Se or selenides in acid, anaerobic environments, studies were conducted with dairy cattle, sheep, and horses fed sodium selenate to determine whether Se from this source was more bioavailable than Se from sodium selenite. A 2-wk period of no Se supplementation was followed by 49 or 56 d of Se supplementation at .3 mg/kg of dietary DM. Serum Se concentrations and glutathione peroxidase (GSHPx) activities measured initially and periodically thereafter revealed no difference between Se forms in sheep and horses and only a small (P less than .05) advantage for selenate in supporting serum Se concentration in dairy cattle. Selenium concentrations in skeletal muscle and liver of sheep were not different between Se forms. Serum Se, but not GSHPx, increased with time, and .3 mg of supplemental Se per kilogram of dietary DM from either sodium selenate or sodium selenite supported normal serum Se concentrations in sheep, dairy cattle, and horses.

Gram-Negative Septicemia and Trace Element Alterations in Tissue and Plasma: Effects of Superoxide Dismutase and Allopurinol

Alterations of trace element concentrations in plasma and liver tissues in four groups of animals were investigated: group A, septic animals treated with superoxide dismutase; group B, septic animals treated with allopurinol; group C, control septic animals without treatment, and group D, nonseptic control animals. Septicemia was achieved by intraperitoneal capsule placement of a mixture of <i>Escherichia coli </i>and <i>Bacteroides fragilis. </i>On the 3rd day after bacterial challenge, surviving animals were sacrified. The mortality rate during the first 3 days were group A, 78%, group B, 54%, group C, 63%, and group D, 0%. Plasma zinc decreased significantly in groups A and C, but was normal in group B. There was a significant decrease in liver zinc content in groups A, B, and C when compared with control, group D; similar changes occurred in liver copper content. Liver selenium content was significantly increased in group B. In conclusion, a dramatic depletion of zinc and copper was found in liver tissue and plasma during septicemia. However, animals treated with allopurinol showed significantly fewer changes. It was concluded that free radical formation could be an important factor during infection and that xanthine oxidase inhibitors have a protective effect, reflected in lower mortality rates.

Concentrations of iron, copper, zinc and selenium in liver of Atlantic salmon Salmo salar infected with Vibrio salmonicida

Lethal infections with Vlbno salmonicida result in a significant reduction in liver concentrations of iron, copper, and selenium expressed as mg kg' wet wt liver. Infections also increase liver weight as the hepatic sonla t~c index (HSI) is higher in dead and moribund fish than in survivors and non-infected fish. The net result is that total liver content of these minerals is not significantly d~fferent between healthy and diseased, experimentally Infected fish. Hitra Disease is a significant disease problem in Norwegian fish farming. While some authors suggest this is a complex multifactorial disease syndrome resembling vitamin E/selenium deficiency in domesticate animals (Fjdstad & Heyeraas 1985, Poppe et al. 1985, 1986), others (Egidius et al. 1981, 1984) emphasize the importance of a Vibrio sp. frequently isolated from fish suffering from Hitra Disease. This Vibrio sp. can produce the clinical signs of Hitra Disease in challenge tests (Hjeltnes et al. 1987) and has been proposed as a new species, Vibrio salmonicida (Egidius et al. 1986). Hapatic levels of iron, copper, zinc, and selenium have been reported to be much lower in farmed Norwegian salmon than in wild salmon, and fish suffering from Hitra Disease have levels that are even further reduced (Poppe et al. 1986). Several authors have viewed this as support for the hypothesis that nutritional and/or metabolic disorders are important components of Hitra Disease. The data suggest 2 opposing hypotheses: infection of fish with Vibrio salmonicida may be secondary to tissue deficiency of these rninerals, the deficiency actually enhancing susceptibility to the bacterium; or, reduced tissue levels of trace elements may be a result of infection with the bacterium. This study was undertaken to investigate the latter

A multi-element supplement for grazing sheep. II. Accumulation of trace elements in sheep fed different levels of supplement

Sheep were fed an oaten hayllupin mixture (88: 12 W/W) containing either 0, 1.7, 3.3, 6.3, 12 or 21% of a multi-element mineral mix for 6 months. Each sheep was fed sufficient ration to provide 800 g DM of the oaten hay/lupin mixture per day. The accumulation of essential and of potentially toxic elements in the tissues of the sheep was measured together with feed intake and growth. Some sheep which were offered 12% and all of the sheep which were offered 21% minerals in the diet refused to eat part or all of the ration and were removed from the experiment. All sheep in the other groups and two sheep which were fed 12% minerals ate all or most of the ration for 6 months. All sheep in the groups which were fed 0, 1.7, 3.3 and 6.3% (equivalent to 0, 15, 30 and 60 g/day of minerals) grew at 27-35 g/day and had similar dry matter intakes after intake of minerals was excluded from the calculation. The two sheep which were fed 12% mineral throughout (equivalent to 120 g/day) lost 6 g/day during the experiment. Intake of minerals increased selenium concentrations in whole blood and liver, and vitamin B12 in plasma. Selenium did not accumulate to levels that resulted in toxicity to the sheep nor exceed maximum permitted levels for human consumption. Fluorine in rib bone increased as mineral intake increased, and sheep which were fed 12% minerals in the diet were at risk of chronic fluorosis. The intake of mineral mix had no significant effect on the concentrations of copper and iron in the liver or the concentration of cadmium in the kidney.

Changes in ornithine decarboxylase activity and polyamine levels in response to eight different forms of selenium

The biological activity of selenium is known to depend on its chemical form. In this study, eight forms of selenium that differed in oxidation state or degree of methylation were studied for their acute effects on the activities of ornithine decarboxylase (ODC) and S-adenosylmethionine decarboxylase (AdoMet DC) and on the concentrations of the polyamines putrescine, spermidine, and spermine in the liver. The polyamine pathway was studied because it is involved in the control of cell growth and in the cell's response to trophic, carcinogenic, and toxic stimuli, activities that selenium has been reported to affect. Female Sprague Dawley rats were administered 12 μmol Se/kg body weight via intraperitoneal injection and were sacrificed six hours later. Injection of sodium selenate, sodium selenite, selenomethionine, Se-methylselenocysteine, selenobetaine, and selenobetaine methyl ester resulted in significant increases in liver selenium, whereas injection of dimethylselenoxide and trimethylselenonium chloride did not. ODC activity and AdoMet DC activity were induced by those selenium compounds that also increased liver selenium content, but the magnitude of enzyme induction by those compounds was not correlated with the hepatic concentration of total selenium determined fluorometrically. Furthermore, the induction of ODC activity by the various forms of selenium did not result in concomitant increases in putrescine, spermidine, and spermine except in the case of selenite. Given that alterations in the metabolism of selenium are induced when the level of tissue selenium is elevated and that the relative abundance of various selenometabolites can be affected by the point of entry of selenium into intermediary metabolism, these data suggest that the changes that were observed in enzyme activities and polyamine levels are likely to be associated with the accumulation of a specific metabolite of selenium. The relevance of these findings to elucidation of the biological activities attributable to various forms of selenium is under investigation.

Interaction between accumulation of cadmium selenium in the tissues of turbot Scophthalmus maximus

The interaction between accumulation of waterborne cadmium and selenite in juvenile turbot, Scophthalmus maximus, was investigated in the laboratory. Intestine, kidney and liver of turbot exposed to 150 μg Cd 1 −1 accumulated cadmium linearly with time over 5 wk at rates of 0.50, 0.014 and 0.11 μg Cd g −1 dry wt. d −1, respectively. Gills, skin and muscle reached steady-state cadmium levels of ca. 15, 0.8 and 0.25 μg Cd g −1 after 1–3 wk of exposure. Plasma and erythrocytes reached steady-state concentrations of ca. 0.1 and 1–2 μg Cd ml −1 after 1–2 wk of exposure. Exposure to 105 μg Se-SeO 3 2−1 −1 did not consistently alter selenium concentrations in gills, skin, liver, muscle and erythrocytes of juvenile turbot. Kidneys accumulated selenium linearly (0.029 μg Se g −1 dry wt. d −1) with time over 5 wk, while intestine reached a steady-state level after 2 wk. Selenium concentrations in the plasma were maintained close to the ambient level throughout the exposure time. Concurrent exposure to selenite augmented cadmium accumulation rates in gills, kidney and liver and reduced cadmium accumulation in intestine and erythrocytes; cadmium accumulation in spleen, skin, muscle and plasma was not affected. Concurrent exposure to cadmium depleted erythrocytes and partly skin of selenium and reduced accumulation of selenium in kidney and plasma, whereas selenium accumulation patterns in gills, intestine, liver, muscle and spleen were not affected by exposure to cadmium.

Trace elements and organochlorines in surf scoters from San Francisco Bay, 1985

Surf scoters (Melanitta perspicillata) were collected from 6 locations in San Francisco Bay during January and March 1985. Overall, mean concentrations of cadmium and zinc were higher in livers of scoters from the southern region of the Bay, whereas mean iron and lead were higher in those from the northern Bay region. Mean concentrations of arsenic, copper, lead, zinc, aluminum (January only) and iron (January) also differed among individual locations. Mean concentrations of copper and zinc increased, arsenic decreased, and cadmium remained the same between January and March. Selenium and mercury concentrations in scoter livers were not significantly correlated (P>0.05), but cadmium concentrations in livers and kidneys were positively correlated (P<0.0001), and body weight was negatively related to mercury concentration in the liver (P<0.05). Body weight differed among locations but not between January and March. Body weight was correlated with lipid content (P<0.0001). DDE and PCBs were each detected in 34 of 36 scoter carcasses. DDE increased significantly between January and March at Richmond Harbor, but BCBs did not differ between January and March at the 3 locations that could be tested.

Ascorbate-2-sulfate as a dietary vitamin C source for Atlantic salmon (Salmo salar): 2. Effects of dietary levels and immunization on the metabolism of trace elements

Atlantic salmon fingerlings were fed a vitamin C deficient diet for four months. The fish were then provided a dry, practical fishmeal based diet supplemented with 0, 500 or 5000 mg vitamin C/kg as L-ascorbic acid or equivalent amounts of ascorbate-2-sulfate. After six weeks on these diets ten fish in each group were injected with a soluble antigen (NIP11-LPH). Six weeks thereafter blood, liver, kidney, spleen and vertebrae were examined for trace elements. The livers were also analysed for metallothionein.The vitamin C deficient fish were anemic despite the significantly elevated iron concentrations in the liver. Vitamin C had no positive effect in lowering tissue levels of cadmium. The highest level of dietary vitamin C given as ascorbic acid reduced the liver selenium concentrations. In response to antigen injection, the fish in all groups showed increased levels of hepatic metallothionein, copper, zinc and cadmium, while hepatic selenium and iron levels were less affected. The elemental composition in other organs was affected by the antigen injection to a minor extent.

Zinc, cadmium, mercury and selenium in minke whales, belugas and narwhals from West Greenland

Samples of muscle, liver and kidney from 24 minke whales (Balaenoptera acutorostrata), 43 belugas (Delphinapterus leucas), and 98 narwhals (Monodon monoceros) were analyzed for zinc, cadmium, mercury, and selenium. Highly significant age accumulation of mercury was found. A lower level of significance of age accumulation of cadmium in belugas and narwhals is probably due to the fact that some of the highest cadmium concentrations are in subadults and young adults. The maximum concentrations of cadmium and mercury are very high: 1.68, 73.7, and 125 μg cadmium, and 9.88, 42.8, and 4.61 μg mercury per g wet weight of narwhal muscle, liver and kidney, respectively. The cadmium concentrations are correlated in the three organs, as are mercury and to a lesser extent selenium concentrations. The concentrations of mercury and selenium in liver are highly correlated.

Effect of dietary selenium on the induction of altered hepatic foci and hepatic tumors by the peroxisome proliferator ciprofibrate

The purpose of this study was to determine if the dietary antioxidant selenium could inhibit hepatocarcinogenesis induced by peroxisome proliferators, which are hypothesized to induce tumors by increased production of hydrogen peroxide or other reactive oxygen species. Rats were fed diets containing the peroxisome proliferator ciprofibrate and one of three concentrations (0.04, 0.2, or 1.0 ppm) of selenium for 6 or 21 months. The incidence of hepatic tumors and the number and volume of gamma-glutamyl transpeptidase-positive, ATPase-negative, glucose-6-phosphatase-negative, and glucose-6-phosphatase-positive foci at 21 months were lower in rats fed higher levels of selenium (no foci or tumors were seen at 6 mo). Indices of oxidative damage in the liver (thiobarbituric acid reactants, conjugated dienes, and lipid-soluble fluorescence products), however, were not decreased in rats fed the high-selenium diet. Therefore, selenium was protective against ciprofibrate-induced hepatocarcinogenesis, but not by reducing the degree of oxidative damage. The liver selenium and glutathione concentrations, and liver selenium-dependent glutathione peroxidase activity, increased as dietary selenium increased. Therefore, inhibition of carcinogenesis by selenium was correlated with increased levels of glutathione and glutathione peroxidase, but these did not inhibit the indices of oxidative damage. Peroxisomal beta-oxidation also increased with the dietary selenium content; it therefore does not appear to be a factor in the inhibition of hepatocarcinogenesis in rats fed higher levels of selenium.

Selenium accumulation by raccoons exposed to irrigation drainwater at Kesterson National Wildlife Refuge, California, 1986

In February-March 1986, eight raccoons (Procyon lotor) were collected at Kesterson Reservoir (Merced Co., California), which had received selenium-contaminated irrigation drainwater, and four raccoons were collected at the nearby Volta Wildlife Area, which had not. Selenium concentrations in Kesterson raccoons averaged 19.9 ppm (micrograms/g dry wt) in liver, 28.3 ppm (dry wt) in hair, 21.6 ppm (dry wt) in feces, and 2.61 ppm (wet wt) in blood and exceeded Volta concentrations by 12, 30, 21, and 10 times, respectively. Selenium concentrations in livers of Kesterson raccoons were less than those in five of nine other mammal species sampled in 1984. Selenium concentrations in hair provided the strongest statistical separation between study areas. Hemoglobin levels in two Kesterson raccoons equalled levels reported in rats with selenium-induced anemia, but the raccoons showed no illness. Amyloidosis in one Kesterson raccoon may have been selenium-induced. Our data indicate that raccoon births peaked about 2 months later than was previously reported. Based on our sample of 12 raccoons, we found no evidence that contamination by irrigation drainwater had negative effects on raccoons inhabiting Kesterson.

Maternal and Fetal Selenium Concentrations and Their Interrelationships in Dairy Cattle

Paired dam-fetus serum, whole blood and liver samples were collected from 101 pregnant dairy cattle at slaughter to establish mean values for fetal tissue selenium concentration and to determine relationships between maternal and fetal selenium status. Samples were assayed for selenium concentration in serum, whole blood and liver and for whole blood glutathione peroxidase (GSH-Px) activity. Fetal age was estimated from fetal crown-to-rump length. Mean fetal liver (2.14 micrograms/g dry wt) and serum (21.4 ng/ml) selenium concentrations and whole blood GSH-Px activity (21.6 mu/ml) differed (P less than 0.0001, 0.0001 and 0.01, respectively) from corresponding maternal values (0.95 micrograms/g liver dry wt; 44.0 ng/ml; 16.7 mu/ml, respectively), while no differences were found between whole blood or erythrocyte selenium concentrations. Fetal liver selenium concentration was greater than corresponding maternal liver selenium in 99% (96/97) of the dam-fetal pairs, suggesting efficient placental transfer and fetal concentrating ability. Maternal liver selenium concentration was most highly correlated to all fetal tissue selenium concentrations and used to develop prediction models. These data suggest that selenium efficiently passes the placenta, and based on published values of adequate adult liver selenium concentrations and maternal-fetal relationships, we suggest an adequate liver selenium concentration in the bovine fetus to be greater than 2.2 micrograms/g liver dry wt, and in whole blood, greater than 120 ng/ml.

Impaired Reproduction of Mallards Fed an Organic Form of Selenium

We fed mallards (Anas platyrhynchos) diets supplemented with 0-, 1-, 2-, 4-, 8-, or 16-ppm selenium in the form of selenomethionine. We fed another group of mallards a diet containing 16-ppm selenium as selenocystine. Females fed the control diet produced a mean of 8.1 ducklings that survived to 6 days of age, which was significantly greater than the 4.6 young produced by females fed 8-ppm selenium as selenomethionine and the zero surviving young of females fed 16-ppm selenium as selenomethionine. Selenocystine did not impair reproduction. Diets containing 8and 16-ppm selenium as selenomethionine caused malformations in 6.8 and 67.9%, respectively, of unhatched eggs compared with 0.6% for controls. The most common malformations were of eyes, bill, legs, and feet. Selenium did not affect the onset or frequency of egg laying, egg size, shell thickness, fertility of eggs, or sex ratio of ducklings. Reduced survival and growth occurred in ducklings hatched from groups whose parents had received 8or 16-ppm selenium as selenomethionine, even though all ducklings were fed a control diet. Concentrations of selenium in eggs and liver of adults could be predicted from dietary concentrations. We conclude that the dietary threshold of selenium as selenomethionine necessary to impair reproduction is between 4 and 8 ppm. It is difficult to identify 1 level of selenium in eggs that will be diagnostic of reproductive impairment in the field because different chemical forms of selenium appear to have different toxicities in eggs. However, when eggs from a wild population contain > 1-ppm selenium on a wet-weight basis, reproductive impairment may be possible and should be evaluated in that population. At 5-ppm selenium in eggs, reproductive impairment is much more likely to occur. J. WILDL. MANAGE. 53(2):418-428 Selenium is a trace element in the earth's crust and, in small amounts, is essential to good health in animals. Too much selenium, however, is toxic to animals. Reproductive failure of chickens caused by selenium poisoning was noted in South Dakota as early as the 1930's (Poley and Moxon 1938). Grains grown on seleniferous soils proved to be the source of the toxic concentrations of

Selenium, vitamin E and polyunsaturated fatty acid concentrations in goat kids with and without nutritional myodegeneration

Mean selenium and vitamin E (alpha-tocopherol) concentrations in the liver, myocardium and skeletal muscle of nine goat kids with nutritional myodegeneration (NMD) were significantly lower than those in a group of nine kids dying from other causes. Each of the 18 kids was from a different property in the southern half of the North Island. The polyunsaturated fatty acid composition of the liver, myocardium and skeletal muscle was not significantly different between the two groups, but the overall level of peroxidisable polyunsaturated fatty acids appeared high in both groups. A further 21 kids with confirmed NMD and live 'controls', submitted as routine cases to Palmerston North Animal Health Laboratory, were included with the above 18 kids in a comparison of liver selenium and alpha-tocopherol concentrations. Kids with NMD had liver selenium concentrations ranging from 170-1100 (mean = 380) nmol/kg and alpha-tocopherol from 0.7-11.0 (mean =2.2) micromol/kg. In control kids, the liver selenium concentration ranged from 530-4300 (mean = 1220) nmol/kg and a-tocopherol from 1.7-14.0 (mean = 5.6) pmollkg. Although these ranges overlapped, the results suggest that liver selenium concentrations <500 nmol/kg and alpha-tocopherol concentrations <2.5 micromol/kg should be regarded as deficient. Liver selenium concentrations from 500-1100 nmol/kg and alpha-tocopherol concentrations from 2.5-10 micromol/kg should be considered marginal. Goat kids appear to require more selenium than lambs or calves which may explain the higher prevalence of NMD in kids. In some cases, however, the disease is associated with low alpha-tocopherol suggesting that supplementation with selenium alone may not always be sufficient.

Effect of dietary sodium nitroprusside as a source of cyanide on the selenium status of chicks given diets of varying selenium concentration.

1. The interaction between dietary cyanide, given in the form of sodium nitroprusside (SNP), and selenium has been studied in two experiments with growing chicks from 14 to 38 d of age. 2. In experiment 1, dietary selenium at 10 mg Se/kg reduced growth, food intake and efficiency of utilisation, and increased relative liver size and selenium content. All of these effects were eliminated by the addition of 0.1 g SNP/kg except for liver selenium content, which progressively declined towards control values as SNP was increased to 0.4 g/kg in increments of 0.1 g/kg. At 0.3 g SNP/kg, cyanide toxicity, as judged by decreased growth, reached significance. 3. In experiment 2, similar effects were observed with selenium at 10 mg Se/kg and SNP at 0.3 g/kg, but selenium deficiency was not evident from growth indicators when selenium supplementation of the diet was omitted completely, nor did these indicators suggest that deficiency was induced by cyanide. 4. In both experiments, plasma and liver glutathione peroxidase activity reflected the dietary selenium content. There was an interaction with dietary SNP content. With selenium intake at a toxic level, SNP increased enzyme activity, further evidence of alleviation of selenium toxicity, but when selenium intake was low and normal, SNP decreased activity in liver, an indication that cyanide could induce deficiency. 5. A possible mechanism for alleviation of selenium toxicity is proposed.

Effect of fat on human liver selenium concentration

Liver samples from 94 adult men and eight fetuses were obtained at autopsy from the Helsinki region. After lyophilization, the samples were analyzed for selenium (Se) both before and after extraction of fat with hexane/isopropanol. An inverse exponential relationship (R2 = 0.63) existed between unextracted adult liver Se concentration and the corresponding liver fat concentration. The relationship ceased to exist when Se was determined on the defatted tissue. The mean defatted adult liver Se concentration, 16.8 microM/kg dry wt, was significantly higher (p less than 0.001) than that of unextracted samples, 12.1 microM/kg. The Se concentration of fetal liver was not affected by the fat extraction. An age relationship (p less than 0.01) was found between subjects under 25 y and those over 40 y when the Se concentration was expressed per unextracted liver tissue but when expressed per defatted liver tissue the difference between age groups widened to comprise subjects over 60 y. Hepatic fat (mean Se concentration 2.7 microM/kg) thus constitutes a diluting factor. We conclude that the Se concentration of fatty human liver results in an underestimation of the selenium status of subjects who have an unphysiologically high liver fat concentration.

Estimation of the Relative Bioavailability of Inorganic Selenium Sources for Poultry.: 2. Tissue Uptake of Selenium from High Dietary Selenium Concentrations

An experiment was conducted with 192 day-old male Cobb chicks to study tissue uptake of Se as an estimate of the bioavailability of supplemental inorganic Se sources fed at high dietary concentrations. A basal corn-soybean meal diet (.18 mg Se/kg diet, dry matter basis) was supplemented with 0, 3, 6, or 9 mg Se/kg diet (as-fed basis) as either reagent grade Na2 SeO3, CaSeO3, or Na2 SeO3 plus fumed amorphous carrier or 6 mg Se/kg diet as either Na2 SeO4 or Se metal, and fed for 1 wk.No toxic effects were noted as expressed by mortality; however, there was a reduction (P<.01) in feed intake and daily gain when 9 mg Se/kg diet was fed, suggesting onset of toxicosis. Selenium concentration in liver, kidney, muscle, and plasma increased linearly (P<.01) as dietary Se increased from all sources. Selenium metal produced lower (P<.01) Se concentrations in kidney and muscle than other supplemental sources.Multiple regression slope ratios were used to estimate relative bioavailability values of 100, 103, 99, 112, and 83 for Na2 SeO3, CaSeO3, Na2 SeO3 + carrier, Na2 SeO4, and Se metal, respectively. When these ratios were corrected for the analyzed dietary Se concentration, relative values were 100, 96, 94, 109, and 81 for the above sources, respectively.