Blood-selenium levels and in vitro red blood cell uptake of 75-Se in kwashiorkor

Selenium in global food systems

Food systems need to produce enough of the essential trace element Se to provide regular adult intakes of at least 40 μg/d to support the maximal expression of the Se enzymes, and perhaps as much as 300 μg/d to reduce risks of cancer. Deprivation of Se is associated with impairments in antioxidant protection, redox regulation and energy production as consequences of suboptimal expression of one or more of the Se-containing enzymes. These impairments may not cause deficiency signs in the classical sense, but instead contribute to health problems caused by physiological and environmental oxidative stresses and infections. At the same time, supranutritional intakes of Se, i.e. intakes greater than those required for selenocysteine enzyme expression, appear to reduce cancer risk. The lower, nutritional, level is greater than the typical intakes of many people in several parts of the world, and few populations have intakes approaching the latter, supranutritional, level. Accordingly, low Se status is likely to contribute to morbidity and mortality due to infectious as well as chronic diseases, and increasing Se intakes in all parts of the world can be expected to reduce cancer rates.

Interacting nutritional and infectious etiologies of Keshan disease. Insights from coxsackie virus B-induced myocarditis in mice deficient in selenium or vitamin E

In 1979, Chinese scientists reported that selenium had been linked to Keshan disease, an endemic juvenile cardiomyopathy found in China. However, certain epidemiological features of the disease could not be explained solely on the basis of inadequate selenium nutrition. Fluctuations in the seasonal incidence of the disease suggested involvement of an infectious agent. Indeed, a coxsackievirus B4 isolated from a Keshan disease victim caused more heart muscle damage when inoculated into selenium-deficient mice than when given to selenium-adequate mice. Those results led us to study the relationship of nutritional status to viral virulence. Coxsackievirus B3/0 (CVB3/0), did not cause disease when inoculated into mice fed adequate levels of Se and vitamin E. However, mice fed diets deficient in either Se or vitamin E developed heart lesions when infected with CVB3/0. To determine if the change in viral phenotype was maintained, we passaged virus isolated from Se-deficient hosts, designated as CVB3/0 Se-, back into Se-adequate hosts. The CVB3/0 Se- virus caused disease in Se-adequate mice. To determine if the phenotype change was due to changes in the viral genome, we sequenced viruses isolated from Se-deficient mice and compared them with the input CVB3/0 virus. Six point mutations differed between the parent strain and the recovered CVB3/0 Se- isolates. When the experiment was repeated using vitamin E-deficient mice, the same 6 point mutations were found. This is the first report of a specific host nutritional deficiency altering viral genotype. Keshan disease may be the result of several interacting causes including a dominant nutritional deficiency (selenium), other nutritional factors (vitamin E, polyunsaturated fatty acids), and an infectious agent (virus).

Plasma zinc, copper, selenium, ferritin and whole blood manganese concentrations in children with kwashiorkor in the acute stage and during refeeding

Plasma zinc, copper, selenium, ferritin and whole blood manganese concentrations were measured in 22 children with kwashiorkor on admission to hospital and on days 5, 10 and 30 of refeeding. Twenty similarly aged, healthy, well nourished children served as controls. The mean (SEM) zinc, copper and selenium concentrations of 7.5 (0.93), 10.8 (0.64) and 0.29 (0.02) mumol/l, respectively, in the children with kwashiorkor on admission were all significantly lower than the values of 13.7 (0.66), 25.6 (1.72) and 0.72 (0.04) mumol/l in the controls. In contrast, the erythrocyte manganese level of 1.67 (0.09) micrograms/gHb and the median ferritin concentration of 293 micrograms/dl were significantly higher than in the controls. After 30 days there was full clinical recovery with significant weight gain and a return of the plasma albumin, caeruloplasmin, copper and ferritin to normal. However, manganese remained elevated and zinc and selenium concentrations remained significantly low. Our results suggest that nutritional rehabilitation of children with kwashiorkor is incomplete by 30 days and cannot be judged purely by a return of the plasma proteins to normal. Addition of selected trace elements to the diet may hasten full recovery.

Fatty acid composition of plasma lipids in Nigerian children with protein-energy malnutrition

The fatty acid (FA) composition of the main plasma lipids was analysed in eight well-nourished, generally healthy Nigerian children aged 14.1 +/- 7.2 months and in 17 malnourished children (8 marasmus, 9 kwashiorkor) aged 14.6 +/- 3.8 months within the first 2 days of admission at the Dept. of Child Health, University of Benin. In comparison to the control group, the malnourished children showed a marked decrease of polyunsaturated FA with low linoleic acid, mainly in sterol esters (STE), and severely reduced linoleic acid metabolites, including arachidonic acid, in all lipid fractions. omega-3-FA were not altered except for a reduction of docosapentaenoic and docosahexaenoic acids in phospholipids. Clearly increased values were found for saturated FA in STE and for the non-essential monoenoic FA in all lipid classes. This pattern indicates the presence of essential fatty acid deficiency in the malnourished children. There was no significant difference between marasmus and kwashiorkor. Eight malnourished children were followed up in the early phase of recovery during hospital treatment 14.0 +/- 3.1 days after obtaining the first sample. Linoleic acid had increased again in STE, but its metabolites were as low or even lower than before. An impaired activity of delta-6-desaturase, the rate limiting enzyme of linoleic acid metabolism, in suggested by elevated substrate-product-ratios of this enzyme in untreated children with protein energy malnutrition and in the early phase of recovery, which may be due to low insulin levels, protein and zinc deficiency. The trientetraen ratio (20:3 omega 9/20:4 omega 6) thus is not a reliable indicator of essential FA status in protein-energy malnutrition.

Selenium status of malnourished hospitalized patients

We evaluated selenium (Se) status of 44 hospitalized patients with protein-energy malnutrition. The patients were assigned to "normal" or "low" Se groups-1 and 2, respectively-based on whether the plasma Se level exceeded or was below the value of the mean-2SD of healthy Georgians'. Plasma and erythrocyte Se levels correlated significantly (r = .52, P less than .01). Erythrocyte glutathione peroxidase activity was highly correlated with plasma Se (r = .68) in group 2; there was no significant correlation between these parameters in group 1. In group 2 the mean plasma prealbumin level was significantly lower, and the mean corpuscular volume and serum glutamic oxaloacetic transaminase level were significantly higher compared to group 1. Other nutritional parameters did not correlate with Se status. Concomitant deficiencies of other nutrients were common in both patient groups. Se levels may relate to protein status, and abnormal hematologic and hepatic parameters may reflect low Se status and/or protein-energy malnutrition. Low Se status is common in malnourished patients from a low Se area, and Se supplementation should be included in their nutritional-repletion regimens.

Erythrocyte selenium-75 uptake as a measure of selenium status in weaner sheep, and its relationship to erythrocyte glutathione peroxidase activity

The relationship between in vitro erythrocyte 75Se uptake (75Se uptake) and erythrocyte glutathione peroxidase (EGSHPx) activity was examined in weaner sheep during periods of selenium depletion and repletion, to determine whether 75Se uptake was better correlated than EGSHPx activity to the development of weaner nutritional myopathy. In the 2 trials conducted, only 3 of 45 Merino wether weaners developed clinical myopathy and histological lesions in skeletal muscles. The 75Se uptake values and EGSHPx activities in these 3 sheep were no different from those in the unaffected sheep. There was a significant negative correlation between 75Se uptake values and EGSHPx activities over the entire period of the trials. It could not be demonstrated that 75Se uptake was any better correlated than EGSHPx activity to the development of nutritional myopathy, and it was concluded that EGSHPx activity indicated selenium status better than 75Se uptake in weaner sheep.

Diminished blood selenium levels in alcoholics

Plasma, whole blood, and red blood cell selenium levels were determined by spectrofluorometry in 30 patients with chronic heavy ethanol ingestion (group I) and 20 normal controls (group II). Nutritional and general medical evaluations were also performed. The mean plasma selenium level was 0.065 microgram/ml +/- 0.012 (SD) for group I versus 0.100 +/- 0.016 for group II (p less than 0.0001). Whole blood levels were 0.076 microgram/ml +/- 0.011 versus 0.114 +/- 0.015 (p less than 0.0001), and red blood cell levels were 0.092 microgram/ml +/- 0.016 compared with 0.130 +/- 0.025 (p less than 0.0001), respectively. Mean triceps skin fold was 8.2 mm +/- 3.5 for group I males versus 12.3 mm +/- 5.0 (p less than 0.005) for group II males but was not well correlated with whole blood selenium status (r = 0.33). Nutritional parameters of percentage of ideal body weight, midarm muscle circumference, serum albumin, and total lymphocyte count revealed no differences. Mildly elevated serum aspartate aminotransferase and/or alkaline phosphatase values occurred in 53% of alcoholics, but selenium levels in these patients were no different from those with normal liver tests. We conclude that depressed blood selenium levels occur frequently in patients with chronic heavy ethanol ingestion even in the absence of overt malnutrition. Since selenium deficiency can produce a spectrum of organ injury which resembles that associated with chronic alcoholism, the relationship of selenium deficiency to alcohol-induced organ injury deserves further study.

Selenium sulfide in tinea versicolor: blood and urine levels

The safety of topical selenium sulfide lotion in man has been demonstrated previously. Twenty male patients with a diagnosis of tinea versicolor were randomly assigned to two parallel groups who applied selenium sulfide lotion or the vehicle to the entire skin surface, excluding mucous membranes, for 10 minutes once daily for 7 consecutive days. Blood and urine selenium levels were determined before and after treatment and showed no significant differences between the active drug and vehicle groups on any study day. It would appear that no significant absorption of selenium took place as a result of this treatment regimen.

Blood selenium content and glutathione peroxidase activity in children with cystic fibrosis, coeliac disease, asthma, and epilepsy

Long-term selenium status in children from the North-East of Scotland was estimated using whole blood selenium content (BSe) and glutathione peroxidase activity (BGSH-Px). BSe was significantly lower than the reference range in children with cystic fibrosis, coeliac disease and in older patients with phenylketonuria. Whereas BGSH-Px of all the children with coeliac disease and those with cystic fibrosis aged over 6 years matched the reference range, it was reduced in younger patients with cystic fibrosis and in children with dietetically treated phenylketonuria. No child had clinical features of selenium deficiency. BSe in treated epileptics and asthmatics conformed to the reference range, but BGSH-Px in both groups was increased significantly; this was most evident in those receiving corticosteroid preparations.

Elevated serum selenium in diabetic children

Twenty-seven diabetic children, 16 girls and 11 boys, 5-18 years of age, with a duration of the disease ranging from 2-15 years, comprised the study group. Thirteen children with a similar age and sex distribution, living in the same area served as healthy controls. All 40 children had a normal growth pattern. The mean serum selenium concentration in the diabetic children, determined by neutron activation analysis, was 7.4 +/- 0.8 micrograms/100 ml (mean +/- SD) and in the healthy controls 6.5 +/- 0.8 micrograms/100 ml. The difference between the two groups was statistically highly significant (p less than 0.01). Boys and girls in both groups had nearly identical mean serum selenium levels and no correlation was observed between the selenium concentrations and either the age, weight or height of the children or the indicators of diabetic control. The selenium status in diabetic children has not been reported previously. The possibility of elevated serum selenium in diabetic children in response to altered lipid metabolism is discussed.

The selenium status of Belgian population groups : I. Healthy adults

A moderate level of selenium (Se) was demonstrated in the blood (123 ng/mL), erythrocytes (RBC) (161 ng/mL), and plasma (97 ng/mL) of 110 male and 54 healthy female Belgian adults by using hydride-generation atomic absorption spectrometry. These values agree well with those found in neighboring countries. The study is the first one to report on normal values for these parameters in Belgians.Glutathione peroxidase (GSH-Px) activity has also been assayed. The group in considered nondeficient. Neither the concentration of Se in blood, plasma, or RBC, nor the activity of GSH-Px in the latter, were related to age, sex, blood pressure, or smoking habits. Oral contraception was associated with elevated plasma Se levels as compared to controls (P<0.01).A statistically significant positive relationship existed between the Se concentrations in whole blood or in red blood cells and red blood cell GSH-Px activity (r=0.31,p<0.005).

The selenium status of Belgian population groups : II. Newborns, children, and the aged

The selenium state of 40 elderly Belgian people, residing in geriatric homes, has been evaluated. Data are presented on the selenium (Se) contents of their blood, plasma, and erythrocytes. The activity of glutathione peroxidase (GSH-Px) has been assayed. All data were compared with those obtained for 164 young, working adults as presented in Part I of this study. Plasma selenium levels were significantly lower in the old (73 ng/mL) as compared to the young people (97 ng/mL), but erythrocyte Se levels (200 ng/mL) and GSH-Px activity were significantly higher.The selenium concentration in plasma during infancy has also been estimated. The results reveal a very low Se level during the first months of life, with a gradual increase with age. The results are discussed in the light of literature data.

Selenium: childhood poisoning and cystic fibrosis

Two cases of selenium ingestion in children are described; one child with severe cystic fibrosis died. Both children had cystic fibrosis and both had low serum chloride in association with selenium usage. Neither child was exposed to excessive heat or cold weather, factors known to salt-deplete children were cystic fibrosis, although one child was dehydrated during a summer month on initial presentation. One child had protein-calorie malnutrition, a condition known to enhance selenium toxicity in animals. We conclude that selenium is a potential hazard in its use as a health food fad for children with cystic fibrosis and in overdose ingestions. Thus selenium supplementation may have contributed to the morbidity and mortality reported here.

Selenium requirements in patients with inborn errors of amino acid metabolism and selenium deficiency

The diets of 5 patients with phenylketonuria of maple-syrup-urine disease were supplemented with yeast which was rich in selenium. For 120 days the patients received 45 micrograms Se/day to increase the Se content of their diets to 10--12 ng Se/Kjoule. Before supplementation the selenium content of serum (5--15 ng/ml) and whole blood (10--27 ng/ml), and the activity of the erythrocyte glutathione peroxidase (0.19--2.69 U37/g Hb), amounted to only 10--20% of normal. The serum selenium content reached normal values within 4 weeks of supplementation, followed by normalisation of the selenium content of whole blood within 4--8 weeks. Restoration of the activity of erythrocyte glutathione peroxidase took 9 to 15 weeks--the red cell life span. There was a significant positive correlation between the selenium content of the erythrocytes and the activity of erythrocyte glutathione peroxidase.

Neonatal erythrocyte glutathione peroxidase deficiency as a consequence of selenium imbalance during pregnancy

The red blood cell (RBC) glutathione peroxidase (GSH-Px) activity and routine haematological parameters were measured in 38 healthy north Italian full-term pregnant women and in their newborn infants. In 31 pairs the serum selenium concentration was also measured. Data were compared with those of 20 normal adult controls (10 males and 10 females). Newborn infants exhibited significantly lower RBC GSH-Px activity and serum selenium concentrations than adult controls. Pregnant women had serum selenium values intermediate between those of adult female controls and their newborn infants. In both the pregnant women and newborns the RBC GSH-Px activity correlated with the level of selenium in serum which suggests that the neonatal RBC GSH-Px deficiency may be partially due to insufficient availability of selenium during pregancy. Factors other than selenium concentration, e.g. hormonal and genetic, might also affect the RBC GSH-Px activity as suggested by sex differences and mother/child concordances in enzyme activity found in our cases.

Selenium and total parenteral nutrition

Despite the increasing recognition of selenium (Se) as an essential trace element in man, little is known about its metabolism during total parenteral nutrition (TPN) and the possible development of Se deficiency in high risk patients. From a general population known by its geographical location to have low Se blood levels, we studied a group of 23 surgical patients receiving TPN for at least one week. Whole blood Se levels were less than in the normal general population and, being some of the lowest observed in adult man, approached levels observed in animals with Se-responsive syndromes. Se continued to be lost predominantly in the urine although the Se content of the TPN fluids was very low (less than 0.6 micrograms/24 hr). Patients with excessive volumes of gastrointestinal excretion lost more Se. Se supplementation may be required in some patients receiving TPN.

In vitro metabolism of selenite in sheep blood: factors controlling the distribution of selenium and the labelling of plasma protein

Some factors controlling the distribution of Na275SeO3 in sheep blood were studied in vitro. After centrifuging Na275SeO3-incubated blood most of the radioactivity was found in the plasma. The labelling of plasma protein by 75Se was dependent on the presence of erythrocytes. The degree of labelling of plasma protein increased with erythrocyte concentration. When phosphate-buffered saline-washed erythrocytes were suspended in phosphate-buffered saline and incubated with Na275SeO3 the majority of the 75Se was detected in the erythrocytes. On incubating these labelled erythrocytes with unlabelled plasma there was a transfer of radioactivity to the plasma. The calculated activation energy for the labelling of plasma was 107.52 kJ/mol. Albumin was shown not to be a principal acceptor of 75Se from the erythrocytes by ammonium sulphate precipitation of radioactive plasma. Addition of Na2SeO3 to the labelled blood resulted in the transfer of 75Se from plasma to the erythrocytes. Radioactive plasma incubated at 37 degrees C was thermolabile with respect to its 75Se content whereas in whole blood the degree of 75Se binding to plasma protein did not vary suggesting that a recycling of selenium was occurring in blood. From the results presented an in vitro model of selenium metabolism in blood is postulated.

The selenium state of children. II. Selenium content of serum, whole blood, hair and the activity of erythrocyte glutathione peroxidase in dietetically treated patients with phenylketonuria and maple-syrup-urine disease

The selenium content of serum, whole blood and hair was measured by neutron activation analysis in dietetically treated patients with phenylketonuria (PKU) and maple-syrup-urine disease (MSUD). Follow-up studies showed a decrease of the serum selenium content and the glutathione peroxidase activity of erythrocytes--a selenoenzyme--from normal values at the beginning of the diet to 20% (selenium) and 50% (gluthione peroxidase) of normal within 10--12 weeks of dietary treatment. In 36 patients the serum selenium content was lower at 6.7--28 X 10(-9) g/ml, independent of the age of the patients (0.5 to 10 years). The selenium content of whole blood was reduced: median = 98 X 10(-9) g/g dry weight; range 75 to 165 X 10(-9) g/g dry weitht (healthy children: median = 381 X 10(-9) g/g dry weight; range 245 to 588 X 10(-9) g/g dry weight). The selenium content of hair was markedly lower in the patients (median = 62 X 10(-9) g/g; range 13--140 X 10(-9) g/g) than in healthy children (median = 429; range 213 to 720 X 10(-9) g/g). The mean glutathione peroxidase activity of erythrocytes was reduced to 4.6 +/- 0.64 U37/g Hb, comparison to normal values (mean = 8.8 +/- 0.88 U37/g Hb).

In vivo and in vitro variations of human erythrocyte glutathione peroxidase activity as result of cells ageing, selenium availability and peroxide activation

Cases showing erythrocyte glutathione peroxidase (GSH-Px) defects have been previously described. Our experiments demonstrate that a number of non genetic factors may influence the GSH-Px activity in human erythrocytes. Selenium administration in vivo was followed in four subjects by elevation in erythrocyte GSH-Px activity ranging from 30% to 1400%. Selenium operates mainly in the bone marrow erythroblasts by facilitating the synthesis of active GSH-Px molecules; experiments in vivo demonstrate that, in the youngest erythrocytes, selenium can raise the enzyme activity, but by a different mechanism. The reticulocyte GSH-Px activity appears to depend on selenium availability and may vary over a wide range. In some normal and iron deficient subjects the GSH-Px activity in the youngest erythrocyte fraction was equal or lower than that previously found in whole erythrocytes of patients affected by haemolytic anaemia. During erythrocyte life, GSH-Px activity may either diminish or increase, and these variations are inversely related to the initial GSH-Px activity in youngest cells. In vitro experiments with the addition of acetyl-phynyl-hydrazine strongly suggest that elevation of GSH-Px activity may be due to allosteric enzyme activation by activated oxygen.

The selenium state of healthy children. I. Serum selenium concentration at different ages; activity of glutathione peroxidase of erythrocytes at different ages; selenium content of food of infants

The selenium concentration of serum is age-dependent. The median value at birth (chi=50 X 10(-9)g/ml) amounts to half of the median value of adults (chi=102 X 10(-9)g/ml). After a decrease in early infancy to chi=34 X 10(-9)g/ml it steadily increases to chi=58 X 10(-9)g/ml in the second half of the first year, to chi=82 X 10(-9)g/ml in 1--5 year old children, and to chi=92 X 10(-9)g/ml in school children. The activities of the selenium containing enzyme glutathione peroxidase of erythrocytes are also reduced in early infancy (chi=7.2 +/- 0.36 U37/g Hb), whereas the enzyme activities of cord blood erythrocytes (chi=8.72 +/- 0.76 U37/g Hb) are in the same range as those of older children or adults. The selenium content of some commercially available milk formulas for infants are lower than those of human and cow's milk.

Balance study of twenty trace elements during total parenteral nutrition in man

1. Balances of twenty trace elements (silver, arsenic, gold, bromine, cadmium, cobalt, chromium, caesium, copper, iron, mercury, lanthanum, molybdenum, rubidium, antimony, scandium, selenium, samarium, tungsten and zinc) have been determined in four male patients during total parenteral nutrition incliding fat emulsion and a special solution for addition of Fe, Zn, manganese, Cu, fluorine and iodine, besides calcium and magnesium, to the infusion solutions. 2. The analyses for trace elements were made with the aid of an ion-exchange technique based on neutron activation, and combined with subsequent gamma spectrometry. 3. The intended intravenous supply of trace elements correspond approximately to the analysed supply. However, all the other trace elements determined were found to be unintentionally administered in small amounts. 4. There was a substantial retention of Fe. Other elements retained were Ag, Co, Cr, Cu, Sb, Sc, and W. 5. Particularly Br and Rb were lost by the patients, but negative balances were also found for As, Au, Cd, Cs, Mo, Se and Zn. However, Zn was retained by one patient with short bowel syndrome. 6. The serum concentrations of thirteen (Ag, Br, Co, Cs, Cu, Fe, Hg, Mo, Rb, Sc, Se, W and Zn) of the trace elements were found to have some decrease during the period of total parenteral nutrition, mostly in accordance with the corresponding balance values, Fe, in particular, was found to have the derectional change in concentration. 7. The administration of trace elements is recommended in long-term total parenteral nutrition.