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PubMed2004

Gestational changes in concentrations of selenium and zinc in the porcine fetus and the effects of maternal intake of selenium.

The effect of maternal dietary selenium (Se) and gestation on the concentrations of Se and zinc (Zn) in the porcine fetus were determined. Mature gilts were randomly assigned to treatments of either adequate (0.39 ppm Se) or low (0.05 ppm Se) dietary Se. Gilts were bred and fetuses were collected throughout gestation. Concentrations of Se in maternal whole blood and liver decreased during gestation in sows fed the low-Se diet compared to sows fed the Se-supplemented diet. Maternal intake of Se did not affect the concentration of Se in the whole fetus; however, the concentration of Se in fetal liver was decreased in fetuses of sows fed the low-Se diet. Although fetal liver Se decreased in both treatments as gestation progressed, the decrease was greater in liver of fetuses from sows fed the low- Se diet. Dietary Se did not affect concentrations of Zn in maternal whole blood or liver or in the whole fetus and fetal liver. The concentration of Se in fetal liver was lower but the concentration of Zn was greater than in maternal liver when sows were fed the adequate Se diet. These results indicate that maternal intake of Se affects fetal liver Se and newborn piglets have lower liver Se concentrations compared to their dams, regardless of the Se intake of sows during gestation. Thus, the piglet is more susceptible Se deficiency than the sow.

Animals↗
PubMed2001

Determination of beryllium and selenium in human urine and of selenium in human serum by graphite-furnace atomic absorption spectrophotometry.

For human urine beryllium (Be), each sample (500 microl) was diluted (1+1) with Nash reagent (containing 0.2% (v/v) acetylacetone and 2.0 M ammonium acetate buffer at pH 6.0) and then a 20-microl volume of Triton X-100 (0.4%, v/v) aqueous solution was added. An aliquot (10 microl) of the diluted urine mixture was introduced into a graphite cuvette and was atomized according to a temperature program. The method detection limit (MDL, 3sigma) for Be was 0.37 microg/l in the undiluted urine sample and the calibration graph was linear up to 65.0 microg/l. Calibration graphs were prepared by the standard addition method. Accuracies of 98.6-102% were obtained when testing standard reference material (SRM 2670) freeze dried human urine samples. Precision (relative standard deviation, RSD) for urine Be was < or = 2.3% (withinrun, n = 5) and was < or = 3.0% (between-run, n = 3). For human urine and serum selenium (Se), samples (100 microl) were diluted with HNO3 (0.2%, v/v) to make a (1+1) dilution for urine analysis or a (1+4) dilution for serum analysis. An additional aliquot (10 microl) of Triton X-100 (0.1%, v/v) was added to each 200 microl of (1+1) diluted urine (or 20 microl of the Triton X-100 was added to each 500 microl of (1+4) diluted serum) sample. After the diluted sample mixture (10 microl) was introduced into a graphite cuvette, the corresponding chemical modifier (10 microl, containing Ni2+ + Pd + NH4NO3 in HNO3 (0.2%, v/v)) was added to it and the mixture was atomized. The MDL (3sigma) for Se in urine and in serum was 4.4 and 21.4 microg/l in undiluted sample, respectively, and the calibration graphs were linear up to 150 and 400 microg/l. Accuracies of urine Se were 98.9 - 99.4% by testing SRM 2670 (NIST) urine standards with RSD (between-run, n = 3) within 2.9%; and that of serum Se was 97.2% when testing a certified second-generation human serum (No. 29, #664) with RSD (between-run, n = 3) of 1.4%. The proposed method can be applied easily, directly, and accurately to the measurement of Be and Se in real samples (including six urine Se and four serum Se from patients of Blackfoot Disease in Taiwan).

Beryllium↗
PubMed1996

Evaluating the efficacy of selenium-enriched yeast and sodium selenite on tissue selenium retention and serum glutathione peroxidase activity in grower and finisher swine.

Three experiments conducted with grower-finisher pigs evaluated sodium selenite and a Se-enriched yeast source at various dietary Se levels on Se retention, tissue and serum Se concentrations, and serum glutathione peroxidase (GSH-Px) activity. Experiment 1 was a balance trial conducted in a 2 x 3 factorial arrangement in a randomized complete block (RCB) design in six replicates. Both Se sources were added at .1, .3, or .5 ppm Se. Crossbred barrows (n = 36) averaging 35.9 kg BW were placed in individual metabolism crates and fed their treatment diets, with feces and urine collected for a 7-d test period. Selenium retention increased as dietary Se levels increased, particularly when the Se-enriched yeast was provided, resulting in a Se source x Se level interaction (P < .01). As dietary Se levels increased, urinary Se increased more when pigs were fed sodium selenite, whereas fecal Se increased more when the Se-enriched yeast was fed; both excretion routes resulting in Se level x Se source interaction responses (P < .01). Experiments 2 and 3 were conducted as RCB involving grower (n = 210) and finisher (n = 266) pigs, respectively, and evaluated the two Se sources each at .1, .3, or .5 ppm Se with a non-Se-fortified basal diet serving as a negative control. In Exp. 2, pigs were fed their treatment diets from 22.2 to 60 kg BW in five replicates, whereas in Exp. 3 diets were fed from 65.8 to 105 kg BW in six replicates. Grower pigs fed sodium selenite had serum GSH-Px activity that reached a plateau at .1 ppm Se and .3 ppm when the Se-enriched yeast source was fed, but the interaction response was not significant (P < .15). During the finisher period, serum GSH-Px activity reached a plateau at .1 ppm Se for both Se sources. Serum Se concentrations were lower at .1 ppm Se when the Se-enriched yeast source was fed, resulting in a source x level interaction response for both grower (P < .05) and finisher (P < .01) periods. Loin Se contents were higher in grower and finisher pigs as dietary Se levels increased when the Se-enriched yeast was fed, resulting in a Se source x Se level interaction (P < .01). The results suggest that more Se was retained in muscle tissue when the Se-enriched yeast source was fed, that serum GSH-Px activity reached a plateau at approximately .1 ppm Se, and that sodium selenite may be more biologically available for GSH-Px activity than the Se-enriched yeast source.

Animals↗
PubMed2005

Effect of the chemical form of supranutritional selenium on selenium load and selenoprotein activities in virgin, pregnant, and lactating rats.

Virgin, pregnant, and lactating rats were used to assess the influence of selenomethionine and selenocystine, fed at four to seven times the daily Se requirement (supranutritional), on Se load and selenoprotein activities. Female Sprague Dawley rats (n = 48; age = 13 wk), reared on a low-Se torula yeast diet, were assigned to one of three reproductive states (n = 16 per reproductive state) to occur simultaneously: virgin, pregnant, and lactating. Once reproductive state was achieved, rats were fed (ad libitum) either l-selenomethionine (n = 24) or L-selenocystine (n = 24) diets providing 2.0 microg Se/g of diet (as-fed basis) for 18 d, and then killed. Lactating rats consuming selenomethionine had the greatest Se concentration in the brain, with pregnant rats being intermediate, and virgin rats having the least (P < 0.02). When selenocystine was fed, the concentration of Se in the brain was greater (P = 0.008) in lactating rats, but not different (P = 0.34) between pregnant and virgin rats. Selenium concentrations in the heart, liver, lung, muscle, spleen, plasma, placenta, uterus, and fetus were greatest (P < 0.001) in rats consuming selenomethionine. Brain, kidney, and liver thioredoxin reductase, and brain, erythrocyte, kidney, and liver glutathione peroxidase activities did not differ (P = 0.13 to P = 0.85) between Se treatments. Lactating rats exhibited the greatest (P < 0.006) Se concentration in the heart, lung, muscle, plasma, and spleen compared with pregnant and virgin rats. Thioredoxin reductase was greatest (P < 0.004) in the brain of pregnant rats, greatest (P < 0.004) in the liver of lactating rats, and greater (P < 0.03) in the kidney of lactating and pregnant vs. virgin rats. Regardless of reproductive state, supranutritional Se (2.0 microg/g of diet) fed as selenocystine resulted in less Se load, and when fed as selenomethionine, was equally available for thioredoxin reductase synthesis as the Se in selenocystine. Independent of dietary Se chemical form, thioredoxin reductase activity was responsive to reproductive state.

Animals↗
PubMed2005

Time-dependent influence of supranutritional organically bound selenium on selenium accumulation in growing wether lambs.

Crossbred wethers (n = 36; BW = 36.0 kg; SD = 3.4) were used to assess the time-dependent influence of supranutritional organically bound Se on Se accumulation. Four wethers were slaughtered before the trial began (d 0). The remaining wethers were fed diets containing adequate (0.2 microg of Se/g of DM) or supranutritional Se (2.9 microg of Se/g of DM; in the form of high-Se wheat grain) for 14, 28, 42, or 56 d before slaughter (four wethers per Se treatment at each slaughter day). The DMI was set at 3.1% of BW and adjusted weekly based on a targeted ADG of 150 g. Daily Se intake by wethers fed the adequate and supra-nutritional Se diets ranged from 5.3 to 5.9, and 79.0 to 95.0 microg of Se/kg of BW, respectively, and did not differ (P = 0.84 to 0.99) between slaughter day groups within Se treatment. Neither Se treatment nor Se treatment x slaughter day interactions were significant for BW, G:F, or liver, kidneys, and spleen weights (P = 0.06 to 0.84). Within the supranutritional Se treatment, Se contents of most organs and tissues from wethers slaughtered on d 14, 28, 42, and 56 were nearly twice the concentrations (P < 0.01) of wethers slaughtered on d 0. When regressed against the number of days the wethers were fed supranutritional Se, Se concentrations increased (P < 0.001) cubically in kidneys and plasma, quadratically in duodenum, lung, liver, and spleen, and linearly in heart, muscle, and wool. For total Se in kidneys, liver, and spleen, the response was quadratic (P < 0.03). Excluding skeletal muscle, heart, and wool, Se in other organs and tissues reached apparent steady-state concentrations 14 to 28 d after commencement of supranutritional Se diets. Selenium concentrations in skeletal muscle accumulated in a linear manner (P < 0.001) throughout the 56-d feeding period. High-Se grains can be used strategically to deliver supranutritional Se and rapidly enhance Se depots in sheep, a task that does not seem attainable with Se salts. Furthermore, a 100-g portion of uncooked loin (LM) from the wethers fed supranutritional Se contained 196 to 250% of the recommended Se requirement for humans.

Animal Feed↗
PubMed1983

Effects of vitamin E and selenium injections on reproduction and preweaning lamb survival in ewes consuming diets marginally deficient in selenium.

Medium wool ewes were injected with vitamin E and(or) Se over a 2-yr period to evaluate the influence of these treatments on reproduction. Ewes were divided randomly into four groups, consisting of a control, plus groups receiving monthly sc injections of either 272 iu vitamin E, 4 mg Se or 272 IU vitamin E plus 4 mg Se during pregnancy. Selenium administration increased (P less than .05) ewe blood Se concentrations, but had no effect (P greater than .10) on fertility (number of ewes lambing of ewes bred), prolificacy (number of lambs born/ewe lambing) or lamb sex ratio. Preweaning survival of lambs was increased (P less than .05) by ewe treatments with either Se or vitamin E and thus, treated ewes weaned approximately 20% more lambs/ewe mated than did control ewes.

Animals↗
PubMed1985

Effects of riboflavin supplementation and selenium source on selenium metabolism in the young pig.

The effect of dietary riboflavin (B2) supplementation and selenium (Se) source on the performance and Se metabolism of weanling pigs was studied. Pigs fed a B2-supplemented (10 mg/kg) casein-glucose diet for 18 d gained faster than pigs fed the B2-unsupplemented diet. Percentage active erythrocyte glutathione reductase (GR) declined rapidly when pigs were placed on the B2-unsupplemented diet and was lower (P less than .01) than that of B2-supplemented pigs after 12 d on test. Percentage active erythrocyte GR values fell below 50% before other B2 deficiency signs became evident. Supplementation of diets with 10 mg B2/kg resulted in increased kidney and muscle glutathione peroxidase (GSH-Px) activity. The Se concentration of liver and heart increased and plasma Se levels decreased with dietary B2 supplementation. Riboflavin supplementation and Se source did not alter apparent Se absorption, but B2 supplementation decreased urinary Se and thus increased Se retention. Also, there was less urinary Se excretion when selenomethionine was the dietary Se source and consequently more Se was retained than when sodium selenite was the dietary Se source. In a final trial, B2 supplementation increased kidney, muscle, heart and brain GSH-Px activity when sodium selenite was the dietary Se source, but not when selenomethionine was the dietary Se source.

Animals↗
PubMed1985

Effect of inorganic selenium supplementation on selenium retention in postweaning swine.

A total of 64 weanling pigs was used in a randomized complete-block experiment to evaluate the efficacy of various inorganic Se levels on weekly Se balance measurements over a 5-wk post-weaning period. Four-week-old weaned pigs were fed a 20% protein, corn-soybean meal diet supplemented with 0, .3, .5 or 1.0 ppm Se from sodium selenite. Eight pigs were allotted by weight, litter and sex to each metabolism crate. A 2-d preliminary period followed by a 5-d collection period was conducted for five weekly periods. Feed intake was provided ad libitum but was similar between dietary Se levels. Fecal Se excretion increased each week and with increasing dietary Se level. Apparent digestibility of Se was relatively constant for each period when inorganic Se was fed, averaging approximately 70%, whereas it ranged between 30 to 40% for pigs fed the basal diet during wk 2 through 5. Urinary Se decreased during the postweaning periods for pigs fed the basal diet, but increased linearly as dietary Se increased during the initial 2-wk postweaning period and then quadratically during wk 3 through 5. There was a net loss of Se from the body when the Se-unsupplemented basal diet was fed during the initial 2 wk postweaning, whereupon, it became positive. Selenium retention in pigs supplemented with inorganic Se increased each week of the trial. When Se retention was expressed in relation to Se intake, the resulting regression was linear (R2 = .99), suggesting that Se retention in the postweaning pig increased in direct proportion to the amount consumed when diets contained up to 1.0 ppm Se.

Animals↗
PubMed1988

Effects of time and dietary selenium concentration as sodium selenite on tissue selenium uptake by sheep.

Thirty crossbred wethers (60 kg avg initial wt) were used to study the time-dose response to dietary Se as sodium selenite (Na2SeO3). Sheep were fed a basal diet (.20 mg/kg Se, M basis) for 10 d; three wethers were killed and tissues were collected for controls. The remaining 27 sheep were assigned randomly to diets supplemented with either 3, 6 or 9 mg/kg Se (as-fed basis) from reagent grade Na2SeO3 and fed for 10, 20 or 30 d. Feed offered was restricted to 1,200 g daily and tap water was available ad libitum. Sheep were stunned and killed by exsanguination and liver, kidney, muscle, heart and spleen were removed and frozen for Se analysis. No toxic effects were noted as expressed by feed intake or hemoglobin concentration. Added dietary Se increased Se linearly (P less than .01) in liver, kidney, and serum. Selenium in liver, kidney and serum also increased (P less than .01) as time advanced. Serum, liver and kidney were more sensitive to dietary Se than were muscle, heart and spleen. Ten days appeared to be an adequate length of time for further Se bioassay studies of this nature. Reagent grade Na2SeO3 was nontoxic when fed to sheep for 30 d at levels up to 90 times the Se requirement.

Animals↗
PubMed1987

Prepartum supplementation of selenium and vitamin E to dairy cows: assessment of selenium status and reproductive performance.

Incidence of retained placenta in dairy cows was evaluated in 627 parturitions. The herd was divided prepartum into three groups: 1) control, no treatment (n = 217 cows); 2) cows injected intramuscularly (n = 190) 21 to 10 d prior parturition with 45 mg Se and 2040 IU of vitamin E; and 3) cows intraruminally administered (n = 220) with two 30-g pellets containing 10% elemental selenium 2 mo prior to expected calving. Incidence of retained placenta (22.1%) was not reduced by Se in combination with vitamin E injection or intraruminal Se pellet nor were other measures of reproduction improved for cows fed a prepartum diet adequate in Se. At parturition the blood plasma Se concentrations were higher in treated postpartum with Se than in untreated cows. No difference in blood plasma Se was observed at parturition between cows with or without placenta retention. Cows dosed intraruminally with Se had a significant increase in milk Se, but this was too small to be a danger to human health. The present results on placenta retention suggest that this disorder is not a Se responsive disease in the dairy cow.

Animals↗
PubMed1999

Significance of amount and form of dietary selenium on blood, milk, and casein selenium concentrations in grazing cows.

Organic selenized yeast enriched with selenoamino acids or inorganic sodium selenate (Na2SeO4) was administered per os three times weekly as a drench for 133 d to previously unsupplemented cows that were grazing low Se pastures. Treatment groups received the equivalent of 2 or 4 mg of Se/d of either supplement form. Control cows did not receive a drench. Samples of blood and milk were collected regularly throughout the trial. Selenium concentrations in blood, milk, casein, and liver and glutathione peroxidase activity in blood and liver are reported as responses per milligram of Se intake. Mean blood Se concentrations in treated cows increased steadily and, by d 133, were 4.7 to 8.8 times that in controls. Selenized yeast was 2 to 3 times more effective than was Na2SeO4, and low Se intakes were 27% more efficient per milligram of Se administered than were high Se intakes at increasing milk Se concentration. Casein Se content mirrored that of milk; among all treated and control cows and throughout the trial, the molar ratio of Se in casein as a percentage of the Se in whole milk was constant at 71 +/- 1.2%. The Se concentration in liver biopsies taken on d 133 was indicative of total Se intake during the trial and ranged from 920 to 3920 nmol of Se/kg of fresh weight. These results demonstrate the differing efficacy of organic and inorganic Se dietary supplements to increase dairy cow Se status and to enhance Se content of milk and casein.

Animals↗
PubMed1988

tert-butyl hydroperoxide-induced hemolysis of alpha-tocopherol-decreased erythrocytes from selenium-deficient and selenium-adequate rats.

The protective function of alpha-tocopherol, glutathione (GSH), and glutathione peroxidase (GSH-Px) from tert-butyl hydroperoxide (t-BuOOH)-induced hemolysis was studied with the erythrocytes from male Wistar rats fed selenium (Se)-adequate or -deficient diet for 3 months. By the preincubation with a water-soluble radical initiator, 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH), at 10 mM for 6 h at 37 degrees C, alpha-tocopherol levels of the erythrocytes were decreased to 40% of the original level, that is, to the level insufficient for supporting the normal functions of the erythrocytes. With the Se-deficient cells, the hemolysis proceeded rapidly irrespective of the presence or absence of GSH in the incubation medium, and irrespective of the presence or absence of AAPH in the preincubation medium. Contrarily, GSH suppressed the hemolysis of Se-adequate cells which were preincubated with and without AAPH. These results are consistent with the notion that Se serves as the prime, important defense mechanism in the t-BuOOH-induced hemolysis through the activity of GSH-Px. Either alpha-tocopherol or GSH by itself, or both by themselves, may not play so significant a role as Se does in suppressing the hemolysis.

Amidines↗
PubMed1991

The necessity of dietary vitamin B6 to selenium biopotency for tissue selenium and glutathione peroxidase in rats.

Necessity of dietary vitamin B6 to the biopotency of selenium (Se) for the levels of Se and glutathione peroxidase (GSH-Px) in tissues was investigated. Male Wistar 12-week-old rats were fed a vitamin B6-Se-deficient basal diet for 3 weeks, and then the rats were divided into 6 groups. One group was fed the basal diet, the others were fed the diet supplemented with 250 micrograms vitamin B6/100 g as pyridoxine.HCl, or 0.25 mg Se/kg as Na2SeO3 (SeL) or DL-selenomethionine (Se-Met), or both (SeL+B6 or Se-Met+B6) for 10 week. The levels of Se and GSH-Px in erythrocytes and muscle were significantly higher in vitamin B6-supplemented groups than in vitamin B6-deficient groups. There was little effect of this vitamin deficiency on Se level in liver of rats fed SeL; however, a higher Se level in liver was observed in vitamin B6-deficient rats fed Se-Met than in the corresponding B6-supplemented rats. A significant decrease of GSH-Px activity in liver was found in vitamin B6-deficient animals fed Se-Met compared with vitamin B6-supplemented animals, whereas no significant decrease was observed in those fed SeL. These results suggest that this vitamin is involved in the transport and deliverance of Se in plasma to the other tissues and the incorporation of Se from Se-Met to GSH-Px in liver.

Animals↗
PubMed1999

An evaluation of the bioavailability of selenium in high-selenium yeast.

The bioavailability of selenium (Se) in high-Se yeast (SeY) was evaluated by measuring tissue Se accumulation and glutathione peroxidase (GSHPx) activity. For 4 weeks, 4-week-old male Wistar rats were fed a Torula yeast-based Se-deficient diet (basal diet) or a diet supplemented with a graded level (0.04, 0.08, 0.16, and 0.32 microgram/g) of Se as either sodium selenite or SeY, which was obtained from two different sources. Se supplementation did not influence growth, hematological values, or serum biochemical tests. Se contents and GSHPx activities in the liver, serum, and erythrocytes increased gradually with increases of the supplemented Se. At lower Se levels (0.04 and 0.08 microgram/g), selenite produced higher Se deposition and higher GSHPx activities than SeY did, but at a higher Se level (0.32 microgram/g), SeY showed higher measures. Strong correlations were detected between the supplementary Se levels and the tissue Se contents or GSHPX activities when the regression was fitted to this equation: R-Rb = m log X + k, where R represented tissue Se content or GSHPx activity in rats fed the diet supplemented with Se at X level, Rb corresponding mean value in rats fed the basal diet, m slope, and k constant. The bioavailability of Se in SeY, as assessed by slope ratio analysis using selenite as a reference Se, was 135% to 165% in the tissue Se content and 105% to 197% in the GSHPx activities. These results indicate that Se in SeY is more bioavailable than selenite Se, and therefore it is the preferred form for supplementation.

Animals↗
PubMed2002

Digestibility and chemical species of selenium contained in high-selenium yeast.

To evaluate the bioavailability of selenium (Se) in high-Se yeast (SeY), the digestibility and chemical species of Se in SeY were investigated. Both Se and nitrogen in SeY were readily released into the soluble fraction through trypsin digestion. In a Sephadex G-25 gel chromatography of the trypsin digest of SeY, the range in which Se was eluted was coincident with the range in which peptide fragments were eluted. Se was distributed almost uniformly within the range and there was no fraction that contained Se in a specifically high amount. A proteolytic enzyme extract of SeY was found to contain Se as selenomethionine (74.8%), selenocystine (9.9%), selenite (5.1%) and as at least three unknown Se compounds (10.2%) when analyzed using high-performance liquid chromatography-inductively coupled plasma mass spectrometry (HPLC-ICPMS). These results indicate that Se in SeY is mainly present as selenomethionine non-specifically incorporated into peptide chains and is highly digestible. Accordingly, it is concluded that the bioavailability of Se in SeY is high.

Chromatography, High Pressure Liquid↗
PubMed1985

Effect of dietary selenium concentration and duration of selenium feeding on hepatic glutathione concentrations in rats.

Studies were conducted in rats to determine the effect of dietary selenium (Se) concentration on hepatic glutathione concentrations and enzyme activities associated with the maintenance of the cellular glutathione status. Male rats were fed 0.1, 3.0, or 6.0 ppm Se as Na2SeO3 for 2, 4, or 6 weeks at which time they were killed and analyses were performed. Both 3.0 and 6.0 ppm Se caused a significant dose-dependent increase in hepatic-reduced glutathione (GSH) by 4 weeks of feeding compared to 0.1 ppm Se. The increase in GSH was preceded by significant, dose-dependent increases in oxidized glutathione (GSSG) as well as the GSSG to GSH ratio. Increases in GSSG and the GSSG to GSH ratio as well as in glutathione reductase and glucose-6-phosphate dehydrogenase activities were observed by 2 weeks of high Se feeding. The current findings substantiate previous results demonstrating effects of high Se on hepatic glutathione concentrations (R. A. LeBoeuf and W. G. Hoekstra, J. Nutr. 113:845-854, 1983) and further suggest that increased cellular GSSG concentrations or the GSSG to GSH ratio caused by 3.0 and 6.0 ppm dietary Se signals for "adaptive" changes in hepatic glutathione metabolism.

Administration, Oral↗
PubMed1995

Use of stable isotopic selenium as a tracer to follow incorporation of selenium into selenoproteins.

Stable isotopes of selenium (Se) have been used in human studies to measure Se absorption, retention and excretion. The purpose of this study was to examine whether stable Se could also be used to follow the incorporation of Se into selenoproteins and whether selenoproteins are labeled with stable isotopes the same way they are with radioactive Se. Rats fed either a Se-deficient or a high-Se diet were injected with either a radioactive (75Se) or a stable isotope of Se (77Se), and the liver cytosol was chromatographed on Sephadex G-200. Compared with 75Se, a greater percentage of 77Se was incorporated into cytosol, but the distribution and the effect of dietary Se was similar for both isotopes. New Zealand long-eared rabbits were also injected with either 77Se or 75Se, and the plasma was chromatographed. More of the 75Se was incorporated into the plasma, but again the patterns of incorporation were similar for both isotopes. Plasma from a male subject who ingested 60 micrograms of 77Se was chromatographed, and the stable Se was detected in column fractions and showed a distribution similar to that observed for rabbit plasma. Finally, a polyacrylamide gel electrophoresis (PAGE) method was developed that allowed loading of sufficient protein to analyze for 77Se in individual protein fractions. The distribution of 77Se and 75Se in rabbit plasma was similar. Human plasma was electrophoresed by a similar method and peaks of 56 and 23 kDa were detected. These data show that stable isotopes of Se can be used for selenoprotein production in the same way as radioactive isotopes. They also show that, when physiological amounts of stable Se are ingested by humans, the isotope can be detected in blood-borne proteins separated by column chromatography and PAGE.

Adult↗
PubMedDate not supplied

Daily selenium intake by breast-fed infants and the selenium concentration in the milk of lactating women in western Poland.

BACKGROUND: Human milk is the only natural source of food for infants during the first several months of life. The milk should contain all trace elements in adequate amounts, including selenium (Se). Se is of particular interest because the daily requirement for this element in infants is higher due to their rapid growth. The aim of our study was to determine the Se concentration in human milk and to calculate the daily Se intake by breast-fed infants in western Poland. MATERIAL AND METHODS: The Se concentration was assayed in mature human milk (14 to 58 days after parturition) collected from 352 lactating women living in 7 voivodeships in western Poland. The concentration of Se was measured by the fluorometric method with 2,3-diaminonaphthalene as a complexing reagent. The values were expressed as ng/ml. RESULTS: No significant differences were observed in terms of Se concentration among the milk samples collected from the different voivodeships. However, the highest values were obtained in the northern part of the region. The mean Se concentration was 10.51 +/- 2.76 ng/ml (range: 10.41-10.65 ng/ml). The calculated mean daily Se intake by breast-fed infants was 7.71 microg/day (range: 3.67-17.17 microg/day). CONCLUSIONS: The Se concentration in human milk in the region studied here is uniform, but the daily Se intake of breast-fed infants in the western part of Poland is lower than the recommended daily requirement. The reason for this situation would appear to be low Se content in the soil, and consequently in the foodstuffs from this region.

Adolescent↗