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PubMed2004

Acute pulmonary inflammation induced by lung overloading with selenium particles: leukocyte response and in situ detection of selenium at high resolution.

The kinetics of the acute inflammatory response of the lung was triggered in CD-1 mice by a single intratracheal instillation of a large amount of Se (10 mg); it was studied by quantitative cytology of bronchoalveolar lavage samples, light microscopy, and scanning electron microscopy coupled with x-ray elemental microanalysis. Bronchoalveolar lavage leukocytes were mostly neutrophils and increased from 12 to 24 h of Se treatment and decreased at 72 h. Only less than half of the granulocytes showed ingested Se particles; in contrast, virtually all BAL macrophages contained Se particles. Scanning electron microscopy coupled with X-ray elemental microanalysis revealed that the intracellular Se particles were heterogeneous in size (diameters from 0.4 and up to 14 microm), and that Se inclusions were sometimes accumulated at a pole of the cell. At 72 h after instillation of the particles, Se-loaded alveolar macrophages were migrated in the interstitial space of the alveoli. Se-positive regions had a focal distribution in the lung; accumulation of inflammatory cells erased the alveolar architecture of these areas of the deep lung. Our data indicates that Se overloading of the lung results in: (1) an acute inflammatory response that is dominated by neutrophils; (2) early removal of Se done mostly by alveolar macrophages, and (3) formation of focal areas of invasion of the lung parenchyma by inflammatory infiltrates.

Acute Disease↗
PubMed1985

Selenium status of exclusively breast-fed infants as influenced by maternal organic or inorganic selenium supplementation.

A longitudinal dietary Se supplementation study on lactating mothers was performed to determine the possibilities of improving the Se status of exclusively breast-fed infants. A total of 200 mothers randomized into three groups received either no Se supplements, 100 micrograms of selenite, or 100 micrograms of yeast-Se daily. Maternal and infant serum Se concentrations showed a linear correlation during exclusive breast-feeding. Yeast-Se in the dose administered was safe and more effective than selenite in increasing the Se concentrations of maternal serum and milk, and infant serum. The mean estimated daily Se intakes of the infants were 7.7 +/- 2.2, 8.9 +/- 2.2, and 11.5 +/- 4 micrograms, in the control, selenite, and yeast-Se groups respectively. Though the infant Se intakes of the unsupplemented and selenite-supplemented mothers were below the lower limit of the safe and adequate range as set by the US National Research Council, their serum Se concentrations increased steadily over the 6-mo study period. As maternal serum Se also increased by over 50% during the same period the results suggest that a maternal daily intake of 50-75 micrograms is adequate during lactation.

Breast Feeding↗
PubMed1987

Formula feeding results in lower selenium status than breast-feeding or selenium supplemented formula feeding: a longitudinal study.

Thirty-two infants completely weaned by age 3.2 mo were randomized into two groups. Unsupplemented group was fed cow's milk-based liquid formula containing 3-5 micrograms Se/L. Se-supplemented group received the same formula supplemented with 20 micrograms Se/L. A third group consisted of exclusively breast-fed infants (51 at age 4 mo, 41 at 6 mo, 12 at 9 mo). Mean serum Se concentration in unsupplemented group decreased from 41 to 31 micrograms/L during the first 2 mo and remained constant until age 6 mo increasing gradually thereafter. In Se-supplemented group it increased steadily from 41 to 68 micrograms/L at age 6 mo and remained constant while supplemented formula was used. In breast-fed group it increased steadily until age 9 mo, between the levels of the two formula-fed groups, when it reached the concentration of Se-supplemented group. At age 12 mo no significant differences were present among the three groups.

Animals↗
PubMed1995

Growth and plasma triiodothyronine concentrations are modified by selenium deficiency and repletion in second-generation selenium-deficient rats.

Classical glutathione peroxidase (GPX) is a useful Se-dependent parameter for determining Se status, but loss of GPX activity alone cannot explain the full effects of Se deficiency. The recent identification of type I thyroxine 5'-deiodinase as a Se-dependent enzyme provides a new potentially critical role for Se. To develop a model of impaired growth due to Se deficiency, second generation deficient weanling rats were fed a Se-deficient amino acid diet with adequate vitamin E and methionine. Initial growth rates of deficient males and females were 53 and 63%, respectively, of rats fed 0.1 micrograms Se/g diet. In short-term experiments with deficient males, liver Se and GPX activity were reduced 99%, liver glutathione-s-transferase activity was increased 114%, plasma thyroxine concentrations were increased 67%, plasma triiodothyronine was decreased 23% and the plasma triiodothyronine:thyroxine ratio was decreased 55%, compared with rats fed 0.2 micrograms Se/g diet. When deficient rats were injected on d 14 with 0, 1, 5 or 10 micrograms Se/100 g, rats grew 4.45, 7.62, 7.17 and 9.05 g/d, respectively, over the next 7 d. Injection with 10 micrograms Se/100 g restored plasma thyroxine and triiodothyronine concentrations 7 d later. Rats injected with 1 microgram Se/100 g rat had significantly altered plasma thyroxine and triiodothyronine concentrations 1 but not 7 d after injection. Infusion of Se-deficient rats with 438 ng triiodothyronine/d for 7 d restored plasma triiodothyronine concentrations but did not increase growth rate compared with rats infused with saline. This model produced a significant growth depression that was significantly reversed by as little as 1 microgram Se/100 g rat, but not by triiodothyronine infusion, suggesting that other Se-dependent roles in addition to 5'-deiodinase and GPX are necessary for adequate growth.

Animals↗
PubMed1997

A compartmental model depicting short-term kinetic changes in selenium metabolism in ewes fed hay containing normal or inadequate levels of selenium.

Changes in Se metabolism were studied in ewes fed hay containing normal or inadequate levels of Se. After intravenous injection of 75Se-sodium selenite, blood, feces and urine were collected at different times, and the concentrations of labeled and unlabeled Se were determined. Ewes were killed 1, 5, 9 or 14 d after tracer injection, and tissues were obtained for determination of radioactivity and Se concentration. The data were fitted to a compartmental model using the SAAM/CONSAM computer program, and kinetic parameters and steady-state transport rates were estimated. Daily Se intake (Vi) and fecal excretion (VF) were significantly (P < 0.001) higher in the ewes fed normal hay (6.06 +/- 1.09 and 3.36 +/- 0.88 mumol/d, respectively) than in those fed Se-deficient hay (0.64 +/- 0.18 and 0.26 +/- 0.15 mumol/d). The net absorption (Va) of Se was significantly higher in ewes fed normal hay [3.19 +/- 0.82 mumol/d by the balance method, Va = Vi-(VF -Vf) (Vf = endogenous fecal Se) and 1.05 +/- 0.38 mumol/d by using the model (plasma entry rate, U(1))] than in those fed hay deficient in Se [0.57 +/- 0.33 mumol/d (balance) and 0.28 +/- 0.08 mumol/d (model)]. The efficiency of absorption [alpha = U(1) divided by Vi] was significantly higher (0.46 +/- 0.19) in ewes fed Se-deficient hay than in those fed normal hay (0.18 +/- 0.09). Simultaneous fitting of the tracer data of both the groups showed that changes in hepatic extraction and urinary and fecal excretion were sufficient and necessary to account for the kinetic differences observed between treatments.

Animals↗
PubMed1998

Liver selenium and testis phospholipid hydroperoxide glutathione peroxidase are associated with growth during selenium repletion of second-generation Se-deficient male rats.

We have previously shown that changes in glutathione peroxidase-1 (GPX1; H2O2:oxidoreductase, EC 1.11.1.9), plasma thyroid hormone and glutathione-S-transferase were not associated with changes in growth observed in second-generation (F2) severely Se-deficient rats; we also found that liver phospholipid hydroperoxide glutathione peroxidase (GPX4; EC 1.11.1.12) activity falls in first-generation (F1) Se-deficient rats to 41% of levels in Se-adequate rats. The purposes of this study were to determine the effect of F2 Se deficiency on GPX4 and to detect early changes in Se parameters associated with growth after single, small Se injections. Se-deficient male F2 weanling rats were randomly divided into two groups and fed a Se-deficient crystalline amino acid (0.003 microg Se/g diet; -Se) diet or that diet supplemented for 14 d with 0.2 microg Se/g diet (+Se) as Na2SeO3. Growth of -Se rats was 55% of the rate of +Se rats. Liver Se, GPX1 activity, GPX4 activity and testis GPX4 activity in -Se rats at 14 d were 1, 2, 23 and 13%, respectively, of levels in +Se rats. In a series of experiments, additional F2 male weanling rats were fed the -Se diet for 14 d and then were given an intraperitoneal single saline injection of 0, 1 or 5 microg Se/100 g body weight (BW) as Na2SeO3 and killed 1 or 7 d later. Rats injected with 1 or 5 microg Se/100 g BW grew 36 or 48%, respectively, above the rate of saline-injected rats. Liver Se concentration increased 367% and testis GPX4 activity doubled in rats 1 d after injection of 1 microg Se/100 g BW compared with saline-injected rats; these parameters were further elevated with 5 microg Se/100 g BW injections. Increases in liver Se and testis GPX4 activity were the parameters best associated with improved growth after Se injection, but the molecular role for Se in growth remains unclear.

Animals↗
PubMed2000

Comparison of the effects of dietary selenium, zinc, and selenium and zinc supplementation on growth and immune response between chick groups that were inoculated with Salmonella and aflatoxin or Salmonella.

The effects of four diets (basal diet, Se, Zn, and Se- and Zn-enriched diets) fed to chicks that were administered one of three treatments [Salmonella and aflatoxin inoculation (T1), Salmonella inoculation (T2), or uninoculated (T3)] were investigated for growth and immune responses. We found a significant improvement in growth performance represented by relative body gain (RBG) and feed efficiency (FE), for the Zn- and Se + Zn-enriched diets fed to the T1 and T2 groups. The antibody immune response was significantly improved for the Se enrichment diet in the T1 and T2 groups. The weight of the bursa and thymus, which relate to the level of the immune response, showed significant decreases, whereas the spleen had a significantly increased relative weight (RW) in the T1 group. The variable dietary trace elements supplement increased the thymic RW in the T2 group.

Aflatoxins↗
PubMed2002

The effect of dietary selenium source and level on the uptake of selenium by developing chick embryos.

We studied the effect of dietary source (organic or inorganic) and level of Se on the Se uptake of chick embryos. After receiving a low-Se diet for 16 wk, 126 Leghorn laying hens were randomly assigned to one of seven dietary treatments. Treatments consisted of feeding a low-Se basal diet alone or with one of three levels of added Se (0.1,0.2, or 0.3 mg/kg Se) supplied by sodium selenite or Se-enriched yeast. Fertile eggs were collected after 33 d of feeding the experimental diets. Eggs were subjected to no incubation or incubation for 5, 10, 15, or 20 d. Non-incubated eggs were separated, and the yolk and albumen were assayed separately for Se. Incubated eggs were separated into the embryo and extra-embryonic portions, which were assayed separately for Se. Se concentrations of the yolk and albumen were significantly different among dietary treatments. Compared with eggs from hens fed sodium selenite, yolk and albumen Se concentrations were higher in eggs from hens fed Se yeast. Embryonic and extra-embryonic Se concentrations were higher in eggs from hens fed Se yeast than eggs from hens fed sodium selenite. The largest increase in embryonic Se concentration was observed during Days 10 to 15 of incubation. It was concluded that Se source and dietary inclusion level influenced the Se concentration of portions of developing embryonated eggs and that embryonic Se concentration changed during incubation.

Animals↗