Comparison of selenium determination in liver samples by atomic absorption spectroscopy and inductively coupled plasma-mass spectrometry

Nano selenium improves humoral immunity, growth performance and breast-muscle selenium concentration of broiler chickens

Context Selenium (Se) is an essential trace element and plays pivotal roles in poultry nutrition. Aims The present study was designed to compare the impact of dietary supplementation of different sources of Se on growth performance, Se concentration of breast meat, and immune response of broiler chickens. Methods In total, 300 1-day-old as hatched broilers were randomly allocated to six dietary treatments, with five replicates of 10 birds per each. The experimental diets were as follows: (1) corn–soybean meal-based diet supplemented with 0.30 mg/kg of sodium selenite, (2) basal diet supplemented with 0.30 mg/kg of Se-enriched yeast, and (3–6) basal diet supplemented with 0.15, 0.30, 0.90 and 1.50 mg/kg of nano-Se respectively. Humoral immunity was assessed by antibody titer against a 5% sheep red blood-cell suspension and cellular immunity was measured by administration of phytohaemagglutinin-p at 38 days. Key results Results indicated that during the periods from 1 to 10 days, from 11 to 24 days, from 25 to 42 days and from 1 to 42 days, average daily gain, average daily feed intake, and feed conversion ratio did not differ among the treatments (P > 0.05). Assessment of orthogonal contrasts at the whole phase of feeding showed that the average daily gain in the broilers fed organic Se was significantly (P < 0.05) higher than that in those fed inorganic Se, as well as nano-Se in comparison to organic Se; such effects were not observed in earlier feeding stages. Se supplementation significantly increased the Se concentration of breast muscle (P < 0.0001). The birds that received 1.50 mg/kg of diet nano-Se showed higher (P < 0.05) total immunoglobulin and IgG titers in primary and secondary immune responses against sheep erythrocytes respectively. Toe web swelling after 24 h and 48 h of receiving phytohaemagglutinin-p was not affected by Se supplementation (P > 0.05). Conclusions In conclusion, the addition of nano-Se gave better results than did inorganic (sodium selenite) and organic (yeast selenium) forms of Se in performance traits, breast meat Se concentration and antibody response of broilers. Implications Novel elemental nanometer particulates, including nano-Se, exhibit new characteristics and a different mode of actions in comparison with organic and inorganic forms of Se sources in poultry diets. Inclusion of the nano form of Se in broiler diets and study of productive performance, immunity responses and meat quality leads to improve balanced broiler diets formulation in view of Se.

Selenium Analysis and Speciation in Dietary Supplements Based on Next-Generation Selenium Ingredients

Selenium is essential for humans and the deficit of Se requires supplementation. In addition to traditional forms such as Se salts, amino acids, or selenium-enriched yeast supplements, next-generation selenium supplements, with lower risk for excess supplementation, are emerging. These are based on selenium forms with lower toxicity, higher bioavailability, and controlled release, such as zerovalent selenium nanoparticles (SeNPs) and selenized polysaccharides (SPs). This article aims to focus on the existing analytical systems for the next-generation Se dietary supplement, providing, at the same time, an overview of the analytical methods available for the traditional forms. The next-generation dietary supplements are evaluated in comparison with the conventional/traditional ones, as well as the analysis and speciation methods that are suitable to reveal which Se forms and species are present in a dietary supplement. Knowledge gaps and further research potential in this field are highlighted. The review indicates that the methods of analysis of next-generation selenium supplements should include a step related to chemical species separation. Such a step would allow a proper characterization of the selenium forms/species, including molecular mass/dimension, and substantiates the marketing claims related to the main advantages of these new selenium ingredients.

Amblyomma maculatum SECIS binding protein 2 and putative selenoprotein P are indispensable for pathogen replication and tick fecundity

Selenium, a vital trace element, is incorporated into selenoproteins to produce selenocysteine. Our previous studies have revealed an adaptive co-evolutionary process that has enabled the spotted fever-causing tick-borne pathogen Rickettsia parkeri to survive by manipulating an antioxidant defense system associated with selenium, which includes a full set of selenoproteins and other antioxidants in ticks. Here, we conducted a systemic investigation of SECIS binding protein 2 (SBP2) and putative selenoprotein P (SELENOP) by transcript silencing in adult female Gulf-coast ticks (Amblyomma maculatum). Knockdown of the SBP2 and SELENOP genes depleted the respective transcript levels of these tick selenogenes, and caused differential regulation of other antioxidants. Importantly, the selenium level in the immature and mature tick stages increased significantly after a blood meal, but the selenium level decreased in ticks after the SBP2 and SELENOP knockdowns. Moreover, the SBP2 knockdown significantly impaired both transovarial transmission of R. parkeri to tick eggs and egg hatching. Overall, our data offer new insight into the relationship between the SBP2 selenoprotein synthesis gene and the putative tick SELENOP gene. It also augments our understanding of selenoprotein synthesis, selenium maintenance and utilization, and bacterial colonization of a tick vector.

Temporal trends in metal pollution: using bird excrement as indicator

Past mining and smelting activities have resulted in metal polluted environments all over the world, but long-term monitoring data is often scarce, especially in higher trophic levels. In this study we used bird (Parus major and Ficedula hypoleuca) excrement to monitor metal pollution in the terrestrial environment following 16 years of continuously reduced emissions from a copper/nickel smelter in Finland. In the early 1990s, lead and cadmium concentrations dropped significantly in excrement, but the reduction did not directly reflect the changes in atmospheric emission from the smelter. This is likely due to a continuous contribution of metals also from the soil pool. We conclude that bird excrement can be used to assess changes in the environment as a whole but not specifically changes in atmospheric emission. Inter-annual variation in excrement concentration of especially copper and nickel demonstrates the importance of long-term monitoring to discern significant trends.

Meta-analysis of selenium accumulation and expression of antioxidant enzymes in chicken tissues

A meta-analysis integrating results of 40 selenium (Se) supplementation experiments that originated from 35 different controlled randomized trials was carried out in an attempt to identify significant factors that affect tissue Se accumulation in chicken. Examined factors included: Se source (12 different sources examined), type of chicken (laying hens or broilers), age of birds at the beginning of supplementation, duration of supplementation, year during which the study was conducted, sex of birds, number of chickens per treatment, method of analysis, tissue type, concentration of Se determined and Se added to feed. A correlation analysis was also carried out between tissue Se concentration and glutathione peroxidase activity. Data analysis showed that the factors significantly affecting tissue Se concentration include type of chicken (P=0.006), type of tissue (P<0.001) and the analytical method used (P=0.014). Although Se source was not found to affect tissue Se concentration (overall P>0.05), certain inorganic (sodium selenite), calcium selenite, sodium selenate and organic sources (B-Traxim Se), Se-yeast, Se-malt, Se-enriched cabbage and Se-enriched garlic as well as background Se level from feed ingredients were found to significantly affect tissue Se concentration. The Se accumulation rate (estimated as linear regression coefficient of Se concentrations to Se added to feed) discriminated between the various tissues with highest values estimated in the leg muscle and lowest in blood plasma. Correlation analysis has also shown that tissue Se concentration (pooled data) was correlated to Se added to feed (r=0.529, P<0.01, log values) and to glutathione peroxidase activity (r=0.332, P=0.0478), with the latter not being correlated with Se added to feed. Although significant factors affecting Se concentration were reported in the present study, they do not necessarily indicate the in vivo function of the antioxidant system or the level of accumulated Se as other factors, not examined in the present study, may interact at the level of trace element absorption, distribution and retention.

Selenium determination in biscuits and pasta: development of chronopotentiometric stripping determination by using a sulphide as an internal standard

Being common in chromatographic techniques internal standard method is rarely applied in electrochemical stripping determinations. One of the reasons for such rare use of this elegant quantification method is because optimal conditions of accumulation at the electrode for individual compounds producing a reproducible signal may vary significantly. These criteria are much stricter when selenium is in question due to very complex mechanism of its accumulation at mercury electrodes which implies simultaneous cathodic mercury dissolution and chemical reaction. Elements that are in the analytical step stripped cathodically from mercury electrodes are rare, further limiting the application of the internal standard method when electrochemical selenium determination is in question. In this work the possibility of using sulphide for selenium quantification by chronopotentiometric stripping analysis was investigated. Optimal experimental parameters were defined in two-component systems. Dimensionless factors defining the ratio of proportionality constants of the two elements were calculated for different selenium concentration ranges at different sulphide contents. Sulphide content that was chosen as adequate for selenium concentrations reasonably to be expected in food samples was 500 µg/dm(3). Determined detection limit of chronopotentiometric stripping determination of selenium by using a sulphide as an internal standard was 0.04 µg/dm(3) (RSD=7.6%; n=5). Defined quantification method was confirmed by analysing spiked standard solutions and standard reference material. The method was used for selenium determination in biscuit and pasta samples. Calculated contents were statistically compared with those obtained by using graphite furnace atomic absorption spectrometry.

Comparative efficacy of two standard methods for determination of iron and zinc in fruits, pulses and cereals

Micronutrients are essential elements needed in small amounts for adequate human nutrition and include the elements iron and zinc. Both of these minerals are essential to human well-being and an adequate supply of iron and zinc help to prevent iron deficiency anaemia and zinc deficiency, two prevalent health concerns of the developing world. The levels of zinc and, iron were measured in the Banana, Papaya, Rice, Finger millet, Soybean and Urdbean. Standard Atomic absorption spectroscopy (AAS) method was also applied to all the samples for zinc and iron analysis and compared with inductively coupled plasma mass spectroscopy (ICP-MS). It was observed that there was no matrix interference affecting the determination of both elements interested in all the samples analyzed. Average concentration relative standard deviation and standard deviation were used for the statistical evaluation of the results for both elements. Correlation coefficient was used as statistical model to compare both the techniques.

Comparison of serum zinc levels measured by inductively coupled plasma mass spectrometry in preschool children with febrile and afebrile seizures

Background

Changes in levels of trace elements have been proposed to underlie febrile seizures. Particularly, low zinc levels have been proposed as related factor of febrile seizure. In this study, we investigated whether mean serum zinc levels differed between children with febrile seizure and afebrile seizure.

Methods

Using inductively coupled plasma mass spectrometry, serum zinc levels were measured in 288 children who had been diagnosed with febrile seizures (N=248) and afebrile seizures (N=40). Mean serum zinc levels were compared between the 2 groups.

Results

Mean serum zinc level was 60.5±12.7 µg/dL in the febrile seizure group and 68.9 ±14.5 µg/dL in the afebrile seizure group. A significant difference in serum zinc levels was observed between the febrile and afebrile seizure groups (P<0.001).

Conclusions

Zinc levels in children with febrile seizure were significantly lower than those in children with afebrile seizure.

Excess dietary sodium selenite alters apoptotic population and oxidative stress markers of spleens in broilers

Three hundred 1-day-old avian broilers were fed on a basic diet (0.2 mg/kg selenium) or the same diet amended to contain 1, 5, 10, and 15 mg/kg selenium supplied as sodium selenite (n = 60/group). In comparison with those of 0.2 mg/kg selenium group, the percentages of annexin V-positive splenocytes were increased in 5, 10, and 15 mg/kg selenium groups. TUNEL assay revealed that apoptotic cells with brown-stained nuclei distributed within the red pulp and white pulp of the spleens with increased frequency of occurrence in 10 and 15 mg/kg selenium groups in comparison with that of 0.2 mg/kg Se group. Sodium selenite-induced oxidative stress in spleens of chickens was evidenced by decrease in glutathione peroxidase, superoxide dismutase, and catalase activities and increase in malondialdehyde contents. The results indicate that excess dietary selenium in the range of 5-15 mg/kg of feed causes oxidative stress, which may be mainly responsible for the increased apoptosis of splenocytes in chickens.