Selenium and lead: mutual detoxifying effects

Antagonistic toxic effects of selenium and lead were studied in growing rats. Chronic lead intoxication was produced by cutaneous application of lead naphthenate solution (80-200 mg Pb/kg body weight) for a period of 8 weeks and chronic selenium intoxication was induced by giving 5 ppm, 10 ppm and 15 ppm selenium in drinking water. The growth rate and food consumption of rats receiving selenium in addition to lead approached normal rate while animals treated with only one of them showed hampered growth rate and lower food consumption. The enzymatic activity of delta-aminolevulinic acid dehydrase (ALA-D) in whole blood, liver and kidney and liver P-450 enzyme activity were normal in rats receiving both selenium and lead. The enzymic activities assayed were, however, depressed in the animals receiving either lead or selenium. Assay of lead and selenium in liver, brain, kidney and blood was carried out. Rats receiving both metals and higher concentrations of these metals in the organs studied, as compared to those only receiving one component. The data seem to indicate that the effect of selenium on the toxic effects of lead is similar to its protective role against methylmercury intoxication.     

Health care quality improvements in Rhode Island diabetes mellitus

In the vicinity of the river Aquidabán in Eastern Paraguay occurred in the last years an endemic disease within cattle herds which killed thousands of heads (Mal de Aquidabán [MdA]). The disease was seen in form of an afebrile, paralytic condition characterized by muscle tremors, swaying of the hind quarters, recumbence and sudden death of the animals. Therefore it was described as "Bovine Paraplegic Syndrome". Comparable symptoms in adult cattle have also being seen in Eastern and Central Venezuela. After we found in the peritoneal fluid of 2 animals, which died under typical symptoms, toxins of C. perfringens toxovar D, we started to investigate the occurrence of C. perfringens in the feces of clinical healthy animals on farms, where MdA was diagnosed before. There we found 73% of the isolated strains belonging to toxovar D. In herds with no case of the disease toxovar A was isolated up to 90%. The next step was the production of a vaccine (anaculture) with a high toxin producing strain of C. perfringens toxovar D. 2000 cattle were vaccinated for 3 years twice a year. None of the vaccinated animals diseased. In 2 control-herds some cases of MdA occurred. But we became quite sure that MdA was an infectious disease, when we started to vaccinate cattle of unvaccinated herds where MdA suddenly occurred. One or two animals died in the next 2 days and after this period the endemic disease was immediately stopped.     

LD 50 and selenium concentration in the organs of rabbits following oral administration of sodium selenite and testing of the toxicity of Ursoselevit-Pr?mix

LD50/24hr was established in the first of a series of experiments on 72 rabbits for orally applied sodium selenite. The dosage was 8.62 mg/kg live weight, the confidence interval being (1 - alpha = 0.95) +/- 0.13 mg/kg. The value was four times as high following intravenous application. Complete lethality was recorded from 15 mg Na2SeO3/kg live weight within 21 hours. Thirty-six animals were involved in the second experiment of the series. They had 50 or 100 per cent Ursoselevit-Pr?mix (30 ppm Se) in their rations. Body mass development of the test animals was superior to that recorded from the controls in the first 50 days, after which limit the former declined strongly in a few days. Their general condition worsened. Postmortem findings, following slaughter, included catarrhal enteritis, toxic liver dystrophy, scattered pulpous tumours in the spleen, and interstitial nephritis. In the third experiment (50 per cent Ursoselevit-Pr?mix with 60 ppm Se in the rations), the test animals developed better than the controls during the first two months, after which point they exhibited the same clinical symptoms as those observed in the second experiment, stopped to put on weight, and eventually turned cachectic. The pathomorphological findings were identical with those obtained from the second experiment. The selenium concentrations in the organs of the test animals all were much higher than those of the controls. Their amounts in excess to base values were up to eleven times in the blood, nine times in the liver, twelve times in the kidneys, and 13 times in the muscles.     

Dexamethasone suppresses gene expression and production of IL-13 by human mast cell line and lung mast cells

2,4-Dichlorophenoxybutyric acid (2,4-DB) is principally used in the United States as a herbicide on peanuts, soybeans, and alfalfa. In Europe, it is used on cereals, undersown cereals, lucerne (alfalfa), clover, and clover mixtures. A 1-year chronic toxicity study in the dog was performed on 2,4-DB. Doses in the study of 0, 75, 225, and 450 ppm were administered to six animals/sex/group. The top dose was reduced from 675 ppm during week 7 of the study due to body weight loss and decreased food consumption. Four animals/sex/group were euthanized after 52 weeks of treatment and two animals/sex/group were placed on control diet for 4 weeks and euthanized at week 56. Treatment-related findings included reductions in body weight gain and food consumption, and minor increases in inorganic phosphorus, blood urea nitrogen, creatinine, aspartate aminotransferase, and alanine aminotransferase. After the 4-week recovery period, the only parameter that did not return to control levels was the aspartate aminotransferase. Gross pathology evaluation noted distended gallbladders and decreased organ weights were noted in females for the adrenal, spleen, and ovaries. Histologically, the liver and kidney were the target organs. The data from the study support a chronic no observed adverse effect level of 75 ppm (2.39 and 2.15 mg/kg/day for males and females, respectively) for 2,4-DB. There was no indication of any immunotoxic or oncogenic response in the studies. In conclusion, the findings in this study indicate the general low toxicity of 2,4-DB following chronic dietary exposure in the dog.     

A comparison of the effects of capsaicin with inhibitory nerve stimulation in the rat anococcygeus muscle in vitro

A cross-sectional study of serum selenium levels in patients (n = 59) with different types of cancer from southeastern Spain was carried out using hydride generation atomic absorption spectrometry. The subjects were divided into four groups according to the cancer location (respiratory, digestive, haematological and gynaecological groups). Serum selenium levels in all patients (54.41 +/- 24.80 mg/l) were significantly lower (P < 0.001) than those determined in control groups [healthy subjects from the same area (n = 130) and institutionalized elderly people (n = 93)]. Mean serum selenium concentrations were not significantly different among the four groups considered (P > 0.05). Linear regression analyses performed on serum selenium levels and biochemical markers (total cholesterol, triglycerides, transaminases, uric acid and urea) did not establish any statistically significant correlation (P > 0.05). No significant relationships between serum selenium concentrations and sex or age of patients was observed (P > 0.05). Given the marked overlap between the two ranges of the populations (the means are within approx. 1/2 S.D.) the predictive values of serum selenium are low. Thus, there is indeed a statistical significance between the means, but selenium cannot be used to determine whether or not a patient has cancer disease.     

The prevalence of antibiotic-resistant faecal Escherichia coli in healthy volunteers in Venezuela

Faecal samples were collected from healthy volunteers in two regions in Venezuela, the village of Grulla (n = 195) and the city of Mérida (n = 181), and analysed for the prevalence of antibiotic resistant faecal Escherichia coli as well as the antibiotic susceptibility of the strains isolated. The highest prevalences of resistance were observed for amoxicillin, oxytetracycline, sulfamethoxazole and trimethoprim. The percentages found for Grulla were 46, 38, 44 and 30%, respectively; for Mérida 39, 65, 56 and 36%, respectively. In Mérida, a significantly higher prevalence of resistance for oxytetracycline was found (P < 0.05). Significant differences in the distribution of the MIC values between Grulla and Mérida were observed for amoxicillin, chloramphenicol and oxytetracycline (P < 0.05). In Grulla, the most frequent pattern was resistance to amoxicillin only and in Mérida to oxytetracycline only. Amoxicillin resistance was due to production of TEM1 beta-lactamase.     

Guillain-Barre syndrome in children

Twenty two cases of Guillian-Barré syndrome were studied at the Children's Hospital of the City of Morelia (State of Michoacán, México), in a four-year period; such that number represents tow out 1 000 of the patients hospitalized in that length of time. The subject of this paper is to get acquainted with the clinical features of this syndrome in this part of the country, to establish the usefulness of the study of the spinal fluid and to know the evolution of the disease in relation to the treatment with corticoids. In all of our twenty two cases, there were coincidental features with the ones reported by others; eventhough, the statistics of this syndrome in the childhood are few. The dissociation between the amounts of albumin and the count of cells in the spinal fluid confirms the diagnosis, but its abscence is not enough to exclude it. Apparently, the clinical evolution of this disease is not modified by ths use of corticoids. Finally, the most moderns etiopathogenic concepts of this syndrome are reviewed as well as its probable etiological association with the infectious mononucleosis virus (Epstein-Barr's virus).     

Chemoprevention of colon cancer by organoselenium compounds and impact of high- or low-fat diets

BACKGROUND: Observational and experimental studies have suggested that dietary supplementation with selenium can inhibit the development of colon cancer. However, many forms of selenium are toxic. Consequently, the development of efficacious compounds with low toxicity has been pursued. PURPOSE: Two synthetic organoselenium compounds, p-methoxy-benzyl selenocyanate (p-methoxy-BSC) and 1,4-phenylenebis(methylene)selenocyanate (p-XSC), were tested for their ability to inhibit colon carcinogenesis in rats that were treated with the carcinogen azoxymethane and fed low- or high-fat diets. METHODS: Groups of 5-week-old male F344 rats (42 animals/ group) were fed either a high-fat diet or a low-fat diet with or without added p-methoxy-BSC (10 or 20 parts per million [ppm]) or p-XSC (20 ppm). Two weeks later, 30 animals in each group received a subcutaneous injection of azoxymethane (15 mg/kg body weight); 1 week later, they received a second injection. The remaining 12 rats in each group received two injections of saline. Three days after the second injection of carcinogen or saline, animals being fed diets with p-methoxy-BSC or p-XSC were switched to corresponding organoselenium-free low- or high-fat diets for the remainder of the study to determine the effects of the selenium compounds on the initiation phase of colon carcinogenesis. At that time, groups of animals that had been maintained on organoselenium-free low- or high-fat diets were switched to diets containing p-methoxy-BSC or p-XSC until the end of the study to determine the effects of these compounds on the postinitiation phase of colon carcinogenesis. All animals were killed during the 38th week after azoxymethane or saline treatment, and histopathologic analysis of the colon tumors was performed. Colon tumor incidence and multiplicity were analyzed statistically. RESULTS: No obvious toxic effects were observed following dietary administration of 10 or 20 ppmp-methoxy-BSC or 20 ppm p-XSC. Administration of 20 ppm p-methoxy-BSC in a high-fat diet during the initiation and postinitiation phases of colon carcinogenesis significantly (statistically) reduced colon tumor incidence; 10 ppmp-methoxy-BSC in a high-fat diet significantly reduced colon tumor incidence but only when it was given during the postinitiation phase. Colon tumor incidence was also significantly reduced when 20 ppm p-XSC was given in a high-fat diet during the initiation phase of colon carcinogenesis. When 20 ppm p-XSC was administered in either a high-fat diet or a low-fat diet during the postinitiation phase, both colon tumor incidence and multiplicity were significantly reduced; the greatest reductions were in animals fed a low-fat diet. CONCLUSIONS: In this model system, p-methoxy-BSC and p-XSC are effective agents for the chemoprevention of colon cancer. The effects of p-XSC were enhanced in animals fed a low-fat diet.     

Keratinocyte growth factor protects mice from chemotherapy and radiation-induced gastrointestinal injury and mortality

A total of 963 skeletons (408 Whites and 555 Blacks) from the Terry Collection were studied to examine macroscopic cranial methods of age estimation. The methods of Acsádi and Nemeskéri, Masset, Baker and Meindl and Lovejoy were applied to every skull. The results indicate that the most accurate techniques in this application were those that consider endocranial suture closure. The methods of Acsádi and Nemeskéri and Masset were the most accurate in all the subsamples (by population, sex, sex within population and in total), although the relative accuracy could vary in application to other populations.     

Multinational randomised controlled trial of lubeluzole in acute ischaemic stroke. European and Australian Lubeluzole Ischaemic Stroke Study Group

The purpose of this investigation was to examine whether inhaled nitric oxide (NO) may alter oxidative stress parameters and induce lung inflammation in moderate hyaline membrane disease (HMD). Eighteen moderately premature lambs (130 days gestation, term = 147 days) were randomly assigned to treatment with 20 ppm inhaled NO (n = 8) from the onset of ventilation or used as control (n = 10). Except inhaled NO, treatments were intentionally similar to those applied in clinical situations. The main studied parameters were oxidative stress index measurements on lung parenchyma and in circulating blood, lung parenchyma microscopic examination and bronchoalveolar lavage cell count. We found that 20 ppm of inhaled NO for 5 h did not change significantly either malondialdehyde and total antioxidant status levels in circulating blood, or malondialdehyde, reduced glutathione, glutathione peroxidase and glutathione reductase in lung parenchyma. Amino-imino-propene bond generation, which are lipoperoxidation markers, was similar in both groups. Furthermore, no significant changes in the number of inflammatory cells in lung lavage products and in lung parenchyma microscopic examination could be found. Therefore, these data do not support the hypothesis that short-term NO inhalation increases oxidative stress and lung inflammation in an experimental model of moderate HMD.     

A Laboratory Study of Mild Steel Vapour Phase Corrosion and Its Inhibition by Dicyclohexylamine Nitrite

Abstract

A study was made of the corrosion of mild steel by acetic and formic acid vapours at 65, 75, 85 and 100% relative humidity (RH) and its inhibition by dicyclohexylamine nitrite (DICHAN). Electrochemical and gravimetric techniques were used. The corrosion rate of steel was in the range of < 10–145 mdd and <10–35 mdd for 225 ppm acetic and 300 ppm form ic acid vapours, respectively, at 65-100% RH. DICHAN has been found to provide moderate protection for steel at 65–85% RH. Inhibitor efficiencies were 64% and 71% in acetic and formic acids, respectively, at 100% RH. There is a reasonable correlation between inhibitor efficiencies estimates from weight loss, polarization and noise measurements. X-ray analysis of the corrosion products, in the presence and absence of DICHAN, shows the presence of magnetite (Fe₃O₄), as principal constituent, along with α-FeOOH and γ-FeOOH. The acetic corrosion product film was of porous nature. © 1998 Canadian Institute of Mining and Metallurgy. Published by Elsevier Science Ltd. All rights reserved.

Résumé

On a é tudie la corrosion de l'acier doux par les vapeurs d'acide acetique et d'acide formique, à 65,75,85 et 100% d'humidite relative (HR) et son inhibition parle nitrite de dicyclohexylamine (DICHAN). On a utilisé des techniques é Iectrochimiques et gravim é triques. Le taux de corrosion de l'acier etait de l'ordre de <10–145 mdd et de <10–35 mdd pour 225 ppm de vapeur d'acide acetique et 300 ppm d'acide formique, r é spectivement, à 65–100% HR. On a trouvé que le DICHAN fournissait a l'acier une protection moder é e à 65-85% HR. L'efficacite de l'inhibiteur était de 64% et 71% dans l'acide acetique et l'acide formique, respectivement, à 100% HR. Il y a une correlation raisonnable entre l'efficacite de l'inhibiteur estim é e à partir des perted de poids et la polarisation et les mesures de “bruit”. L'analyse par rayons-X des produits de corrosion, en présence et en absence de DICHAN, montré la pr é senc de magnetit é (Fe₃O₄) comme principal constituant, ainsi que α-FeOOH et γ-FeOOH. Le film du produit de corrosion de l'acide ac é tique etait de nature poreuse. © 1998 Canadian Institute of Mining and Metallurgy. Published by Elsevier Science Ltd. All rights reserved.     

Molecular cDNA cloning and tissue distribution of mRNA encoding a novel ATP-binding cassette (ABC) half-transporter

After feeding a commercial rodent chow for 8 weeks, tissues from male and female rats were collected and examined for selenium content, glutathione peroxidase (GPX) activities and selenoprotein W (Se-W) levels. There were no differences (P > 0.05) between plasma selenium content, plasma GPX activity, whole blood selenium content, or whole blood GPX activity between male and female rats. There was also no gender effect on selenium concentration in muscle, brain, spleen, and skin, but selenium concentration in liver was higher (P < 0.05) in female than in male rats. Western blots indicated that the tissue distribution of Se-W was similar in male and female rats. Se-W protein level was high in testes of male rats but very low in ovaries of female rats. Muscle and skin from female rats had significantly higher (P < 0.05) Se-W levels than from male rats. Consistent with Se-W content, the Se-W mRNA levels from female skins were significantly higher (P < 0.05) than from male rats. The expression of Se-W was different in various tissues and gender influenced this regulation in some tissues.     

The Contribution to Intercrystalline Embrittlement of Soft Metal Films Surrounding Hard Grains

Abstract

In a previous paper, a laboratory scale process was reported for the concentration by flotation of iron oxides from Gossan ore tailings. Further experimentation has shown that minor impurities can be removed from the iron concentrate by a combined chloridizing-volatilization-pelletizing process with the addition of a coke-calcium chloride mixture. The pellets obtained with this treatment were high in iron (64 %), while lead and arsenic were reduced from 2 and 1% respectively, to less than 0.07% each, the sulfur level was reduced from 0.64 to less than 0.01 %, copper and zinc were reduced from 0.04 and 0.03% to 0.03 and 0.01 %, respectively, bismuth from 400 ppm to less than 2ppm and silver from 43 ppm to 4 ppm.

Résumé

On a déjà rapporté un procédé en échelle de laboratoire, sur la concentration par flottation des oxydes de fercontenus dans le résidu de minerai de Gossan. Les impuretés minoritaires peuvent être eliminés du concentré de fer avec un procédé de chloruration-volatilisation-pelletisation avec l'addition d'un mélange de coke et chlorure de calcium. Cette possibilité a été étudiée dans le présent travail. Les éléments contenus dans le concentré de fer sont: fer, 57%; plomb, 2 %; arsenic, 1%; soufre, 0.64 %; cuivre, 0.04 %; zinc, 0.03 %; bismuth, 400 ppm et argent, 43 ppm. Apres l'application du procédé décrit, les contenus qui restent dans les pellets sont: fer,64 %; plomb et arsenic, moins de 0.07 %; soufre moins de 0.01%, cuivre, 0.03 %; zinc, 0.01 %; bismuth moins de 2 ppm et argent, 4 ppm.     

Selenium Refining by Nitrate Fluxing

Abstract

The refining of mist precipitated selenium, assaying approximately 98% selenium, by the addition of a nitrate flux was studied in the temperature range 250–350°C. Optimum operating conditions were identified which yielded a uniform selenium product averaging 99.79% purity. The maximum purity of the selenium product was limited by the inability of the nitrate flux to react with mercury and silver from the feed material. The removal of Cu, Pb, S, Si, Fe, Zn, Bi, Sn, As and Te was greater than 90%, and in some cases approached 100% removal. The major impurities in the selenium product were copper (1000 ppm), mercury (850 ppm), lead and silver (100 ppm).

The application of the nitrate flux proved to be an effective method for the purification of selenium already close to meeting requirements. The purification was accomplished at a fast rate, with low reagent consumption and at low reaction temperatures.     

Selenium deficiency in patients with cardiovascular diseases and its correction with the drug "selena"

Blood selenium concentrations, erythrocytic glutathione peroxidase (GPO) activity, and plasma lipid peroxides were investigated in patients with ischemic heart disease (IHD) and dilated cardiomyopathy (DCMP). Patients with IHD and DCMP displayed depressed activity of GPO with activation of lipid peroxides associated with lower blood selenium. The daily intake of 300 micrograms of selenium from Selena during a month treatment augmented selenium concentrations by 71% in IHD and DCMP patients. This augmentation showed an inverse correlation with primary plasma selenium concentrations. Plasma malonic dialdehyde levels decreased by 17%. The findings suggest that selenium is involved in the pathogenesis of DCMP and IHD, which may be a ground for selecting patients with selenium deficiency for its correction with Selena.     

Selenium content in cattle hair in areas with incidence of nutrition-induced muscular dystrophy

In the South Bohemian Region which is an area of enzootic incidence of nutritional muscle dystrophy selenium content in the fur of dairy cows and young cattle was determined. In the breeds in which the "white muscle disease" appeared in the past years in young cattle, lambs and calves the lowest mean selenium values in the fur dry matter found were: 0.18 +/- 0.07, 0.19 +/- 0.06, and 0.21 +/- 0.08 ppm, with repeated findings of mere 0.09 ppm Se. 60 to 100 per cent samples from these farms showed selenium values below the 0.25 ppm level. The fur of heifers which recovered from nutritional muscle dystrophy and were treated 10 days prior to sampling with a selenium preparation in injection form (Selevit inf. SPOFA) contained 0.29 ppm selenium (+/- 0.11). In other breeds 0.30 +/- 0.07 to 3.33 +/- 0.16 ppm selenium was found in the fur of cows and young cattle. The initial field essay of selenium content in cattle fur indicated a relation of low selenium values to the frequency of clinical forms of nutritional muscle dystrophy in domestic ruminants.     

Diagnostic criteria for selenium toxicosis in aquatic birds: histologic lesions

Chronic selenium toxicosis was induced in 1-yr-old male mallard ducks (Anas platyrhynchos) by feeding selenium, as seleno-DL-methionine, in amounts of 0, 10, 20, 40, and 80 parts per million (ppm) to five groups of 21 ducks each for 16 wk during March to July 1988. All mallards in the 80 ppm group, three in the 40 ppm group, and one in the 20 ppm group died. Histologic lesions in mallards that died of selenosis were hepatocellular vacuolar degeneration progressing to centrolobular and panlobular necrosis, nephrosis, apoptosis of pancreatic exocrine cells, hypermaturity and avascularity of contour feathers of the head with atrophy of feather follicles, lymphocytic necrosis and atrophy of lymphoid organs (spleen, gut-associated lymphoid tissue, and lumbar lymph nodes), and severe atrophy and degeneration of fat. Histologic lesions in surviving mallards in the 40 ppm group, which had tissue residues of selenium comparable to mallards that died, were fewer and much milder than mallards that died; lesions consisted of atrophy of lymphoid tissue, hyalinogranular swelling of hepatocytes, atrophy of seminiferous tubules, and senescence of feathers. No significant histologic lesions were detected in euthanized mallards in the 0, 10 and 20 ppm groups. Based on tissue residues and histologic findings, primarily in the liver, there was a threshold of selenium accumulation above which pathophysiologic changes were rapid and fatal. Pathognomonic histologic lesions of fatal and nonfatal selenosis were not detected. Criteria for diagnosis of fatal selenosis in aquatic birds include consistent histologic lesions in the liver, kidneys, and organs of the immune system. Although histologic changes were present in cases of chronic non-fatal selenosis, these were inconsistent. Consistent features of fatal and non-fatal chronic selenosis were marked weight loss and elevated concentrations of selenium in organs.     

Chronic carvedilol reduces mortality and renal damage in hypertensive stroke-prone rats

The effects of carvedilol, a novel vasodilating beta-blocker and antioxidant, and propranolol on survival, neurobehavioral deficits, cardiovascular parameters, plasma renin, plasma aldosterone levels and renal pathology were determined in stroke-prone spontaneously hypertensive rats. Stroke-prone spontaneously hypertensive rats were allowed access to 1% NaCl as the drinking solution and a high fat diet supplemented with carvedilol (1200 or 2400 ppm) or propranolol (2400 ppm). The control group consisted of stroke-prone spontaneously hypertensive rats placed on the same diet with no drug supplement. Animals fed propranolol had a blood level of 864 +/- 68 ng/ml, whereas carvedilol-fed animals had blood levels of 24 +/- 4 ng/ml at 1200 ppm and 471 +/- 145 ng/ml at 2400 ppm. Carvedilol and propranolol treatment resulted in significant beta adrenoceptor blockade. Both compounds reduced heart rate, but had no significant effects on systolic arterial blood pressure. Carvedilol- and propranolol-treated animals also exhibited significant, prolonged protection from neurobehavioral deficits and mortality (P < .01). Elevated plasma renin activity and aldosterone levels seen in untreated controls were significantly decreased by propranolol (P < .05), and to a considerably greater extent by the same dose of carvedilol (P < .01). Carvedilol decreased renal histopathological damage and cardiac hypertrophy to a greater extent (P < .01) than propranolol (at equal doses). Both carvedilol (P < .01)- and propranolol (P < .01)-treated animals had considerably reduced renal damage at 18 weeks of treatment. Carvedilol reduced renal damage more than propranolol (P < .05). In addition, the lower (1200 ppm) dose of carvedilol, which decreased neurobehavioral deficits and mortality, had no significant effects on organ mass or renal function, but significantly (P < .01) reduced renal damage. These data indicate that both beta adrenoceptor blockers, especially carvedilol to a considerably greater degree, convey significant protection in a genetic model of severe hypertension that results in renal and cardiovascular organ pathology, neurobehavioral deficits and premature death.     

Selenite and selenium yeast as feed supplements for dairy cows

The availability of inorganic and organic forms of selenium to dairy cows was studied by giving 25 cows supplementary selenium for 9 months either as sodium selenite or as a selenium-containing yeast product. Group I (eight cows) received 3.0 mg selenium as sodium selenite daily, group II (nine cows) received 3.0 mg selenium as the selenium yeast product, and group III (eight cows) received 0.75 mg selenium as the selenium yeast product. The total selenium contents of the ration were 0.26-0.32 mg/kg feed dry matter for groups I and II, and 0.16-0.18 mg/kg for group III. The supplement of 0.75 mg selenium daily from the yeast product maintained the selenium concentrations of whole blood and milk at the same levels as 3.0 mg selenium as sodium selenite, and 3.0 mg selenium from the yeast product increased the selenium concentration of whole blood by approximately equal to 40% and that of milk by approximately equal to 100%. The activity of glutathione peroxidase in erythrocytes of the group given selenite was not significantly different from that in either of the groups given the yeast product. The concentrations of selenium in the tissues of two cows from each group were marginal to adequate, and there was a trend for the concentrations to be higher in the tissues of the cows supplemented with the yeast product.