Toenail selenium level among healthy residents of two Polish Districts

The goal of this study was to evaluate the selenium mass fraction in toenail clippings taken from random inhabitants living in various areas of the Pomeranian (Northern Poland) and Lubuskie (Western Poland) Districts. Toenail clippings were analyzed by instrumental neutron activation analysis (INAA) giving means of 0.57±0.10 and 0.60±0.16 mg·kg⁻¹ for the two areas, respectively, but the difference was statistically not significant. In additional, it was found that gender, age, body mass index (BMI), smoking, and selenium supplementation are factors with apparent effects to the selenium levels in toenail clippings.     

Selenium status and cancer mortality in subjects residing in four Canadian provinces

The objective of this study was to measure selenium status in maleand female Canadian subjects relative to cancer mortality in their respectiveprovinces. Toenail specimens from 755 subjects, 377 males and 378 females,living in Vancouver (186), Edmonton (188), Toronto (197) and Montreal (184)were analyzed by instrumental neutron activation analysis giving means of0.968±0.177, 0.950±0.148, 0.932±0.135 and 0.896±0.127ppm Se, respectively. The effect of selenium determinants such as gender,selenium supplementation and smoking on selenium status is presented. Detailsof the observed inverse relationship of selenium status and cancer mortalityare discussed.     

Analysis of the toenail as a biomonitor of supranutritional intake of Zn,Cu, and Mg

The toenail was examined as a biological monitor of Mg, Zn, and Cu intake using an observational case control model. The One Source Cohort matched 63 individuals in Columbia Missouri who took the One Source multivitamin with 63 control individuals. The matching criteria were based on age, sex, ethnicity, smoking status, and body mass index. The multivitamin contained supra-nutritional levels of Se, Mg, Cu, and Zn. The toenail clippings were examined for these elements using instrumental neutron activation analysis (INAA). A statistical analysis did not indicate a significant difference for Mg, Cu, or Zn between the nails of One Source supplement users and control subjects (p<0.76, 0.55, and 0.85, respectively). The trace nutrient Se was used as an internal control. Previous studies have consistently demonstrated that toenail Se is positively correlated with Se supplement use and the analysis did result in a significant correlation in the toenails of One Source users and control subjects (p<1·10⁻⁴). This internal Se control suggests that the One Source Cohort is largely free from misclassification errors that could interfere with the biomonitor response for the supranutritional intake of Mg, Cu, and Zn.     

ESR study of radiation resistance of some aza- and thiacrown ethers at 77 K

The objective of this study was to determine if a stable enriched tracer of Se-76 could be used to establish the delay time between a dietary intake of selenium and its appearance in various matrices. Selenium, an essential trace element, has been investigated at the Missouri University Research Reactor (MURR) for several years. Several matrices have been studied to determine selenium status in humans; these include fingernails, toenails, blood, hair, and urine. A cohort of five women and seven men was utilized for this study. Each subject ingested selenium supplements which were enriched in Se-76 (96.48%). Fingernails, toenails, whole blood, and blood sera were collected as biochemical indicators. Selenium concentrations and glutathione peroxidase activities were determined in blood sera and whole blood to monitor the effect of the selenium supplement in these matrices. Selenium concentrations were determined in fingernails and toenails prior to supplementation and for several months afterward to determine the delay time for the appearance of selenium. The effects of the selenium supplement on the selenium concentrations of the fingernails, toenails, whole blood, and blood sera and the effect of the supplement on glutathione peroxidase activity will be reported.     

Vitamin D status and its associated factors of free living Malay adults in a tropical country, Malaysia

Vitamin D status is influenced by sun exposure, geographic latitude, daily outdoor activities, body surface exposed to sunlight and dietary intakes. Malaysia, is sunny all year round. However, the vitamin D status of this population especially among the healthy and free living adults is not known. Therefore a study of vitamin D status and associated factors was initiated among an existing Malay cohort in Kuala Lumpur. A total of 380 subjects were sampled to have their vitamin D status assessed using 25-hydroxyvitamin D (25(OH)D). A short questionnaire enquiring socio-demographic characteristics, exposure to sunlight and clothing style was administered. Their mean age was 48.5±5.2years and the mean 25(OH)D for males and females were 56.2±18.9nmol/L and 36.2±13.4nmol/L respectively. There were significant positive correlation for sun exposure score (r=0.27, p<0.001) and negative correlation for sun protection score (r=-0.41, p<0.001) with 25(OH)D levels. In the logistic regression model, females (OR=2.93; 95% CI: 1.17, 7.31), BMI (1.1; 1.03, 1.20) and sun exposure score (0.998; 0.996, 0.999) were significantly associated with vitamin D status as represented by 25(OH)D levels. Our findings show that obesity, lifestyle behaviours and clothing style are directly associated with our participants especially females' low vitamin D status.     

Heat Dissipation of Flying Wax Moths (Galleria Mellonella) Measured by Means of Direct Calorimetry

Heat production rates and flight speed of adult wax moths (Galleria mellonella) were investigated by means of direct calorimetry at T_A=20 and 30°C. Specific heat production rates were not significantly different between males and females at T_A=20°C (p_TH=747±123.7 mW g^-1, n=5 for males and p_TH=791±169 mW g^-1, n=5 for females) even with females having a higher body mass (M_B=83.8±21.6 mg, n=9 for males and M_B=146.4±25.7 mg, n=11 for females) and wing load. In females, heat production rates were dependent on temperature with higher heat production rates at T_A=20°C (p_TH=791±169 mW g^-1, n=5) than at T_A=30°C (p_TH=441±74 mW g^-1, n=6). Flight speed was also clearly correlated with T_A. Both males and females flew more slowly at T_A=20 than at 30°C. This revised version was published online in August 2006 with corrections to the Cover Date.     

Determination and distribution of human plasma selenoproteins

Major portions of plasma-selenium are incorporated in the proteins glutathione peroxidase (GSH-Px), selenoprotein P (Sel P) and albumin. A chromatographic method, adapted from a procedure by Harrison et al. [6], uses heparin- and blue-sepharose to separate the three protein fractions. The determination of selenium was carried out by electrothermal atomic absorption spectroscopy (ETAAS) using the Zeeman effect. The selenium distribution of 17 healthy subjects was 68 ± 7% of the total plasma selenium associated to Sel P, 25 ± 4% associated to p-GSH-Px and 7±4% associated to albumin. The recovery of selenium was 99 ± 4%. For precision measurements a plasma pool has been separated seven times. The selectivity of this method was monitored by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and GSH-Px activity measurements. A fast method, adapted for clinical applications, is described which allows to determine the human plasma selenium distribution in about an hour.     

Determination of selenium daily intakes in two small groups of the Portuguese population by replicate sample neutron activation analysis

Selenium daily intake was determined for two small groups of the Portuguese population, based on the analysis of duplicate diet portions. The total amount of food ingested during a day was collected for 18 workers of the Technological and Nuclear Institute (ITN-Sacavém) and for 6 females of Reguengos de Monsaraz, a small town in the south-eastern hinterland. The average selenium daily intake was 43 ± 20 and 32 ± 13 μg per person, respectively, both lower than the Recommended Dietary Allowance (RDA) of 55 μg day⁻¹. Selenium in diet samples was determined by replicate sample neutron activation analysis (RSINAA). The method was considered accurate for the selenium determination.     

Under‐reporting of food intake is frequent among Brazilian free‐living older persons: a doubly labelled water study

The assessment of food intake is essential for the development of dietetic interventions. Accuracy is low when intake is assessed by questionnaires, the under‐reporting of food intake being frequent. Most such studies, however, were performed in developed countries and there is little data about the older population of developing nations. This study aimed to verify the total energy expenditure (TEE) of independent older Brazilians living in an urban area, through the doubly labelled water (DLW) method and to compare it with the reported energy intake obtained through the application of a food frequency questionnaire (FFQ). Initially, 100 volunteers aged from 60 to 75 years had their body composition determined by dual‐energy X‐ray absorptiometry (DEXA). Five volunteers of each quartile of body fat percentage had their energy expenditure determined by DLW. The mean age of the subjects included in this phase of the study was 66.4 ± 3.5 years, and ten of the subjects were men. The mean TEE was 2565 ± 614 and 2154 ± 339 kcal.day^?1 for men and women, respectively. The Physical Activity Level (PAL) was 1.58 ± 0.31 and 1.52 ± 0.22, respectively. Under‐reporting of food intake was highly prevalent, with a mean percentage of reported intake in relation to measured TEE of ?17.7%. Thus, under‐reporting of food intake is highly prevalent among Brazilian independent older persons. The DLW method is an important tool in nutritional studies and its use is to be recommended in developing countries. Copyright © 2010 John Wiley & Sons, Ltd.     

Preliminary Study on the Changes of IgA/VcA Titers in Low Blood Selenium Persons1 Sera by Oral use of Selenium-Enriched Yeast

Abstract

Whole blood selenium (Se) concentrations in 112 IgA/VcA positive and 33 oral administrating Se—enriched yeast subjects and 32 IgA/VcA negative ones were determined, using 2,3—diaminonaphahalene fluorometric method modified by the author. The blood Se levels ([xbar] ± SD) of IgA/VcA positive and negative subjects were 0.115 ± 0.024, 0.118 ± 0.028 μg/ml. respectively, no significant difference was existed between their blood Se levels (P > 0.20). The blood Se levels of low blood Se subjects with IgA/VcA positivity were 0.104 ± 0.009, 0.149 ± 0.033 μg/ml, respectively, before and after oral use of Se—enriched yeast, there were significant differences between their blood Se levels (P < 0.001). However, the efficiency of Se—enriched yeast on the negative change of IgA/VcA titer was only 21.4%. It suggested that blood Se levels are not related with IgA/VcA titers.     

UV doses of Americans.

The UV doses of Americans were never measured, but are needed for assessing the risks of UV-related health effects. We calculated these doses using a novel approach. The Environmental Protection Agency's (EPA) National Human Activity Pattern Survey (NHAPS) recorded the activity profiles of 9386 Americans over 24 months to assess their exposure to environmental pollutants, one of which is UV radiation. NHAPS used randomized telephone interviews to get their previous day's minute-by-minute activities. From NHAPS we extracted only the outdoor-daylight data of the northern and southern indoor workers (95%), stratifying by season, sex and age (0-21, 22-40, 41-59 and 60+ years) to find the average time Americans spend outdoors. Knowing the total daylight time and that while outdoors Americans are exposed to about 30% of the available solar UV (on a horizontal plane), we calculated their percent ambients. The average American's percent ambients are 2.6 and 2.5% for northern and southern females, respectively, and 3.5 and 3.6% for northern and southern males, respectively. Men over 40 years of age have the highest ambients (4%). From their ambients we calculated their annual doses using seasonal averages of UV measurements taken daily for over 2 years by EPA Brewer spectrophotometers located in four quadrants of the United States: Atlanta, GA; Boston, MA; Bozeman, MT and Riverside, CA. The average erythemal UV doses of Americans are about 25,000 J/m2/year, 22,000 for females and 28,000 for males, or 33,000 J/m2/year including a conservative continental U.S. vacation (7800 J/m2). Thus, we can now assess the risks of UV-related health effects for Americans.     

Selenium content of Argentinean infant formulae and baby foods by pseudo-cyclic instrumental neutron activation analysis coupled to Compton suppression

The selenium levels of Argentinean infant formulae and baby food were measured using the 162-keV gamma-ray of ^77mSe (t _½ = 17.4 s) by a pseudo-cyclic instrumental neutron activation analysis (PC-INAA) method in conjunction with Compton suppression spectrometry (CSS). For comparison purposes, 5 selected infant formulae were also analyzed for selenium by a radiochemical neutron activation analysis (RNAA) method. The selenium levels for three samples agreed between ±2.8 and 6.5 % while the other two differed by 12 and 17 % which could perhaps be attributed to sample inhomogeneity. The selenium content of cow milk-based infant formulae varied from 42–146 μg kg^?1 compared to 52–63 μg kg^?1 for soy-based milk formulae. In the case of baby foods, the selenium levels varied from 34 to 74 μg kg^?1. The detection limits for selenium by PC-INAA–CSS for all the samples analyzed in this work were between 8.5 and 65 μg kg^?1 depending on the major elements present in the samples, while it was 20 μg kg^?1 for the RNAA method. The expanded uncertainty (κ = 2) of the PC-INAA–CSS method was 7.0 % at the end of cycle #4 for a sample containing 73.7 μg kg^?1 selenium compared to the RNAA value of 24.2 % for a sample of 67.0 μg kg^?1 selenium content.     

Daily dietary selenium intake of selected Brazilian population groups

Due to its essential characteristics, the daily dietary selenium intake of individuals should be monitored accurately. In the current work, daily selenium intake of different Brazilian population groups based on duplicate portion diet analysis was evaluated and compared with the new estimated average requirement values (EAR), to assess if selenium deficiency or excess could be observed in these groups. Selenium content was determined by neutron activation analysis (NAA). The average daily dietary selenium intake found was 26.3 (±8.3) ·g/day for children from the city of São Paulo, 37.4 (±16.0) ·g/day for children from Belém, 107 (±107) ·g/day for children from Macapá, 28.4 (±7.5) ·g/day for institutionalized elderly, 32 (±6) ·g/day for non-institutionalized elderly and 37 (±17) ·g/day for university students from São Paulo. Most daily dietary selenium intake range observed were below the EAR values. The values obtained for children groups from Belém and Macapá cities, whose intake levels were much higher than the recommendation, were an exception.     

INAA application in the assessment of Ag, Co, Cr, Fe, Hg, Rb, Sb, Sc, Se, and Zn mass fraction in pediatric and young adult prostate glands

The effect of age on trace element contents in intact prostate of 50 apparently healthy 0–30 year old males was investigated by neutron activation analysis with high resolution spectrometry of long-lived radionuclides. Mean values (M ± SΕΜ) for mass fraction (milligram per kilogram, on dry-weight basis) of trace elements were: Ag 0.0708 ± 0.0096, Co 0.0348 ± 0.0040, Cr 0.466 ± 0.069, Fe 100 ± 10, Hg 0.0258 ± 0.0025, Rb 12.6 ± 0.8, Sb 0.0576 ± 0.0066, Sc 0.0125 ± 0.0016, Se 0.478 ± 0.031, and Zn 273 ± 31, respectively. A strongly pronounced tendency of age-related increase in Se and Zn mass fraction and of age-related decrease in Co, Cr, Fe, and Sc mass fraction was observed in period of life from 0 to 30 years.     

Kinetics of FeSe2 oxidation by ferric iron and its reactivity compared with FeS2

The mobility and bioavailability of selenium is a major health and environmental issue and a main concern for geological disposal of high-level radioactive waste. Chemically and/or microbially mediated oxidation of insoluble Se-bearing particulate, such as iron selenides, to dissolved and mobile phases controls the transport and distribution of Se in the environment. The oxidation of ferroselite(FeSe2) by ferric iron was investigated in anoxic conditions. The redox reaction can be represented by: FeSe2 + 2Fe3+ = 2Se0 + 3Fe2+. Kinetic studies indicated that the reaction can be described by second-order rate law, with rate constants of 0.49±0.01, 0.85±0.02, 1.84±0.04, and 3.29±0.13 L mol-1 s-1 at pH 1.62, 1.87, 2.23, and 2.49, respectively. The positive correlation between reaction rate and pH implies that diffusion of Fe3+ oxidant to the mineral surface is the rate-determining step. The strong reactivity of FeSe2 towards Fe3+ suggests that ferric iron may play a significant role in FeSe2 oxidation process(e.g., by Se4+, O2, etc.) and Se0 should be the first reaction product. Also, it was shown that the reduction rate of Fe3+ or Se4+ by pyrite(FeS2) can be significantly increased in the presence of FeSe2, suggesting a stronger reactivity of FeSe2 compared with pyrite. The results obtained extend our knowledge about the subtle interaction between Se, pyrite and iron selenides in the environment, and give insight into the transfer of selenium from iron selenides to bio-available selenium(i.e., selenite and selenate) in the Se-rich environment.     

Determination of cuticular and internal fatty acids of Chorthippus brunneus males and females using HPLC‐LLSD and GC–MS

Insects are of growing significance in veterinary medicine and human healthcare; therefore, an understanding of their biology is very important. The cuticular and internal fatty acid compositions of Chorthippus brunneus males and females have been studied for the first time. The lipids of males and females were separated into classes of compounds using high‐performance liquid chromatography with a laser light scattering detector. The free fatty acid (FFA) fractions obtained by HPLC were silylated and then analyzed by GC–MS. The cuticular lipids of males contained 15 saturated, four unsaturated with even‐numbered and two unsaturated with odd‐numbered carbon chains, FFAs ranging from C8 to C25. The major free fatty acids in males were C16 (20.8%), C18:2 (8.5%), C18:1 (32.9%) and C18 (24.4%). The cuticular lipids of females contained 17 saturated, four monounsaturated and two diunsaturated free fatty acids ranging from C8 to C30. The major cuticular fatty acids in females were C16 (25.1%), C18:2 (6.2%), C18:1 (23.7%) and C18:0 (33.2%). The internal FFAs of males consisted of 20 compounds ranging from C8 to C26. Four of these compounds were detected as major compounds: C16 (14.1%), C18:2 (21.6%), C18:1 (38.0%) and C18 (22.5%). Among 18 internal free fatty acids of females, C16 (22.3%), C18:2 (10.9%), C18:1 (40.2%) and C18 (20.5%) were the most abundant compounds. The following cuticular fatty acids present in the lipids of females were absent in the lipids of males: C26, C27 and C30. On the other hand, only C24 was absent from the cuticular lipids of females. Only C10 and C24 internal fatty acids present in the lipids of males were absent in the lipids of females. Copyright © 2016 John Wiley & Sons, Ltd.     

Determination of trace selenium in human plasma and hair with ternary inclusion compound-fluorescent spectrophotometry

A method for determination of selenium in plasma and hair with ternary inclusion compound-fluorescent spectrophotometry has been developed. The determination of selenium in plasma and hair can be performed directly in aqueous solution. Blood and hair samples were destroyed by oxygen flask combustion. The linear range was 10-500 ng mL-1 for plasma and 10-100 ng mL-1 for hair. Within-day and day-to-day precisions for plasma ranged from 5.4% to 9.3% (n = 7) and from 3.5% to 14.5% (n = 7), respectively. Within-day precisions for hair ranged from 0.6% to 6.2% (n = 7). Recoveries ranged from 91.0% to 97.8% for plasma and from 95.0% to 102.0% for hair. The blood samples from 15 Hans and 20 Uygurs in Xinjiang Uygur automatic region and 23 Hans in Liaoning province were collected and determined. It was indicated that no statistically significant difference in plasma selenium concentration of the Hans between Xinjiang and Liaoning was found (F = 1.36, P > 0.05). However, there were statistically significant differences between the Hans and the Uygurs in Xinjiang (F = 1.01, P < 0.01) and between males and females in the two areas (P < 0.01). There was a low correlation between plasma selenium concentration and hair selenium concentration. The ratio of hair selenium concentration to plasma selenium concentration was 2.17, with a range of 1.63-2.88.     

Hierarchical clustering into groups of human brain regions according to elemental composition

Thirteen brain regions were dissected from both hemispheres of fifteen ‘normal’ ageing subjects (8 females, 7 males) of mean age 79±7 years. Elemental compositions were determined by simultaneous application of particle induced X-ray emissions (PIXE) and Rutherford backscattering (RBS) analyses using a 2 MeV, 4nA proton beam scaned over 4 mm² of the sample surface. Elemental concentrations were found to be dependent upon the brain region and hemisphere studied. Hierarchical cluster analysis was applied to group the brain regions according to the sample concentrations of eight elements. The resulting dendrogram is preseted and its clusters related to the sample compositions of grey and white matter.     

Pervaporation as a Separation Technique for Direct Determination of Volatile Selenium Species by Atomic Fluorescence Spectrometry

Abstract

This paper reports for the first time a suitable way to determine methylated selenium compounds using the new approach of pervaporation coupled to atomic fluorescence spectrcmetry (PV-AFS).

The method developed allows direct extraction, separation, preconcentration and determination of dimethylselenium (DMSe) and dimethyldiselenium (DMDSe) from slurry samples. Under the optimum conditions, the detection limits (LODs) were found to be 0.66 ng and 0.39 ng for DMSe and DMDSe, respectively, the precision being about 6–9 % for 10 ng mL as selenium concentration. The linearity ranges were from the LOD to 0.7 μg mL^?1 for DMSe and from the LOD to 0.4 μg mL^?1 for DMDSe (as Se). The pervaporation efficiencies were 55 ± 1 % and 85 ± 5 % for DMSe and DMDSe, respectively. The proposed method was successfully applied to determine methylated selenium species in sewage sludge, garlic and oyster samples. The concentrations found were from 0.07 to 1.42 μg g^?1.

As no certified reference materials are available for these analytes, validation was carried out by recovery studies in these matrices, and the results showed that the proposed method performed satisfactorily.     

Determination of selenium status using the nail biologic monitor in a canine model

Toenails and fingernails are routinely used to estimate selenium status in epidemiological studies; however, literature validating nail selenium concentration as a surrogate for critical organs is limited. In this study diets of intact male dogs were selenium supplemented at two physiological levels (3 and 6 μg/kg/day) in two different forms, selenomethionine and selenium-enriched bioformed yeast. The selenium-adequate basal diet consumed by the treatment and control groups during the 4-week run-in period and throughout the trial contained 0.3 ppm selenium. After 7 months the dogs in the two treatment groups and the control group were euthanized. Representative tissue samples from prostate, brain, liver, heart and skeletal muscle were collected, rinsed and frozen. Toenail clippings from multiple toes were also collected. Selenium was determined by neutron activation analysis using Se77m (half life = 17.4 s) at the University of Missouri Research Reactor Center. NIST SRM 1577, Bovine Liver was analyzed as a quality control. The analysts were blinded to control and treatment group assignments. As expected, tissue selenium levels increased proportionally with supplementation. A slightly greater increase in tissue selenium was observed for the purified selenomethionine compared to the bioformed yeast; however this trend was significant only for brain tissue. Toenail selenium concentrations and tissue selenium were highly correlated (p < 0.003) with Pearson coefficients of 0.759 (skeletal muscle), 0.745 (heart), 0.729 (brain), 0.723 (prostate), and 0.632 (liver). The toenail biologic monitor accurately assesses selenium status in skeletal muscle, heart, brain, prostate, and liver in the canine model.