Selenium supplementation has beneficial and detrimental effects on immunity to influenza vaccine in older adults.
ABSTRACT: Mortality resulting from influenza (flu) virus infections occurs primarily in the elderly through declining immunity. Studies in mice have suggested beneficial effects of selenium (Se) supplementation on immunity to flu but similar evidence is lacking in humans. A dietary intervention study was therefore designed to test the effects of Se-supplementation on a variety of parameters of anti-flu immunity in healthy subjects aged 50-64 years.A 12-week randomized, double-blinded, placebo-controlled clinical trial (ClinicalTrials.govNCT00279812) was undertaken in six groups of individuals with plasma Se levels <110 ng/mL. Four groups were given daily capsules of yeast enriched with 0 ?g Se/day (SeY-0/d; n = 20), 50 ?g Se/d (SeY-50/d; n = 18), 100 ?g Se/d (SeY-100/d; n = 21) or 200 ?g Se/d (SeY-200/d; n = 23). Two groups were given onion-containing meals with either <1 ?g Se/d (SeO-0/d; n = 17) or 50 ?g Se/d (SeO-50/d; n = 18). Flu vaccine was administrated at week 10 and immune parameters were assessed until week 12.Primary study endpoints were changes in cellular and humoral immune responses. Supplementation with SeY and SeO affected different aspects of cellular immunity. SeY increased Tctx-ADCC cell counts in blood (214%, SeY-100/d) before flu vaccination and a dose-dependent increase in T cell proliferation (500%, SeY-50/100/200/d), IL-8 (169%, SeY-100/d) and IL-10 (317%, SeY-200/d) secretion after in vivo flu challenge. Positive effects were contrasted by lower granzyme B content of CD8 cells (55%, SeY-200/d). SeO (Se 50 ?g/d) also enhanced T cell proliferation after vaccination (650%), IFN-? (289%), and IL-8 secretion (139%), granzyme (209%) and perforin (190%) content of CD8 cells but inhibited TNF-? synthesis (42%). Onion on its own reduced the number of NKT cells in blood (38%). These effects were determined by comparison to group-specific baseline yeast or onion control groups. Mucosal flu-specific antibody responses were unaffected by Se-supplementation.Se-supplementation in healthy human adults with marginal Se status resulted in both beneficial and detrimental effects on cellular immunity to flu that was affected by the form of Se, supplemental dose and delivery matrix. These observations call for a thorough evaluation of the risks and benefits associated with Se-supplementation.
Project description:The uncertainty surrounding dietary requirements for selenium (Se) is partly due to limitations in biomarkers of Se status that are related to health outcomes. In this study we determined the effect of different doses and forms of Se on gene expression of selenoprotein S (SEPS1), selenoprotein W (SEPW1) and selenoprotein R (SEPR), and responses to an immune function challenge, influenza vaccine, were measured in order to identify functional markers of Se status.A 12 week human dietary intervention study was undertaken in 119 volunteers who received placebo, 50, 100 or 200 µg/day Se-enriched yeast (Se-yeast) or meals containing unenriched or Se-enriched onions (50 µg/day). Gene expression was quantified in RNA samples extracted from human peripheral blood mononuclear cells (PBMC's) using quantitative RT-PCR. There was a significant increase in SEPW1 mRNA in the Se-enriched onion group (50 µg/day) compared with the unenriched onion group. SEPR and SEPW1 did not change significantly over the duration of the supplementation period in the control or Se-yeast groups, except at week 10 when SEPW1 mRNA levels were significantly lower in the 200 µg/day Se-yeast group compared to the placebo group. Levels of SEPS1 mRNA increased significantly 7 days after the influenza vaccine challenge, the magnitude of the increase in SEPS1 gene expression was dose-dependent, with a significantly greater response with higher Se supplementation.This novel finding provides preliminary evidence for a role of SEPS1 in the immune response, and further supports the relationship between Se status and immune function.ClinicalTrials.gov [NCT00279812].
Project description:Dietary recommendations for selenium differ between countries, mainly because of uncertainties over the definition of optimal selenium status.The objective was to examine the dose-response relations for different forms of selenium.A randomized, double-blind, placebo-controlled dietary intervention was carried out in 119 healthy men and women aged 50-64 y living in the United Kingdom. Daily placebo or selenium-enriched yeast tablets containing 50, 100, or 200 microg Se ( approximately 60% selenomethionine), selenium-enriched onion meals ( approximately 66% gamma-glutamyl-methylselenocysteine, providing the equivalent of 50 microg Se/d), or unenriched onion meals were consumed for 12 wk. Changes in platelet glutathione peroxidase activity and in plasma selenium and selenoprotein P concentrations were measured.The mean baseline plasma selenium concentration for all subjects was 95.7 +/- 11.5 ng/mL, which increased significantly by 10 wk to steady state concentrations of 118.3 +/- 13.1, 152.0 +/- 24.3, and 177.4 +/- 26.3 ng/mL in those who consumed 50, 100, or 200 microg Se-yeast/d, respectively. Platelet glutathione peroxidase activity did not change significantly in response to either dose or form of selenium. Selenoprotein P increased significantly in all selenium intervention groups from an overall baseline mean of 4.99 +/- 0.80 microg/mL to 6.17 +/- 0.85, 6.73 +/- 1.01, 6.59 +/- 0.64, and 5.72 +/- 0.75 microg/mL in those who consumed 50, 100, or 200 microg Se-yeast/d and 50 microg Se-enriched onions/d, respectively.Plasma selenoprotein P is a useful biomarker of status in populations with relatively low selenium intakes because it responds to different dietary forms of selenium. To optimize the plasma selenoprotein P concentration in this study, 50 microg Se/d was required in addition to the habitual intake of approximately 55 microg/d. In the context of established relations between plasma selenium and risk of cancer and mortality, and recognizing the important functions of selenoprotein P, these results provide important evidence for deriving estimated average requirements for selenium in adults. This trial was registered at clinicaltrials.gov as NCT00279812.
Project description:The crystal structure of dicobalt(II) divanadium(V) disel-enium(IV) undeca-oxide, Co?V?Se?O??, exhibits a three-dimensional framework, the building units being distorted CoO? octa-hedra and VO? square pyramids arranged so as to form alternate chains along . The framework has channels along  and  in which the two ?-SeO?E (site symmetries m; E being the 4s² lone electron pair of Se(IV)) tetra-hedra reside and connect to the other building blocks. The structure contains corner- and edge-sharing CoO? octa-hedra, corner- and edge-sharing VO? square pyramids and edge-sharing ?-SeO?E tetra-hedra. Co?V?Se?O?? is the first oxide containing all the cations Co(II), V(V) and Se(IV).
Project description:Staphylococcal enterotoxins (SEs) are virulence factors of Staphylococcus aureus associated with various toxic diseases due to their emetic and superantigenic activities. Although at least 27 SE(-like) genes have been identified in S. aureus to date, the newly identified SE(-like) genes have not yet been well characterized by their epidemiological features. In this study, the prevalence and genetic diversity of SE gene sey and SE-like genes selw, selx, selz, sel26, and sel27 were investigated for 624 clinical isolates of community-acquired methicillin-resistant S. aureus (CA-MRSA). The most prevalent SE(-like) gene was selw (92.9%), followed by selx (85.6%), sey (35.4%) and selz (5.6%), while sel26 and sel27 were not detected. Phylogenetically, sey, selw, selx, and selz were discriminated into 7, 10, 16, and 9 subtypes (groups), respectively. Among these subtypes, sey was the most conserved and showed the highest sequence identity (>98.8%), followed by selz and selx. The SE-like gene selw was the most divergent, and four out of ten genetic groups contained pseudogenes that may encode truncated product. Individual subtypes of SE(-like) genes were generally found in isolates with specific genotypes/lineages of S. aureus. This study revealed the putative ubiquity of selw and selx and the prevalence of sey and selz in some specific lineages (e.g., ST121) in CA-MRSA, suggesting a potential role of these newly described SEs(-like) in pathogenicity.
Project description:To explore the effect of selenium-enriched yeast (SeY) on intestinal barrier functions in weaned pigs upon oxidative stress, a 2 × 2 factorial design was utilized and thirty-two pigs were randomly assigned into four groups. Pigs with or without exposure to oxidative stress (diquat challenge) were fed with a basal diet or a SeY-containing diet. The trial lasted for 21 days, and result showed that SeY supplementation attenuated body-weight reduction and significantly decreased the serum concentrations of diamine oxidase (DAO) and D-lactic acid in pigs upon diquat challenge (P < 0.05). Diquat challenge decreased the villus height and the ratio of villus height to crypt depth (V/C) in the jejunum and ileum (P < 0.05). However, SeY supplementation not only elevated the villus height and the ratio of V/C (P < 0.05) but also improved the distribution and abundance of tight-junction protein ZO-1 in the jejunum epithelium. Interestingly, SeY supplementation acutely decreased the total apoptosis rate of intestinal epithelial cells in pigs upon diquat challenge (P < 0.05). Moreover, SeY elevated the content of antioxidant molecules such as glutathione peroxidase (GSH-Px) and catalase (CAT) but significantly decreased the content of malondialdehyde (MDA) in the intestinal mucosa (P < 0.05). Importantly, SeY elevated the expression levels of critical functional genes such as the nuclear factor erythroid-2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1), sodium/glucose cotransporter 1 (SGLT1), and B-cell lymphoma-2 (BCL-2) in the intestinal mucosa upon diquat challenge (P < 0.05). Moreover, the expression of caspase-3 was downregulated by SeY in the duodenum and jejunum mucosa (P < 0.05). These results indicated that SeY attenuated oxidative stress-induced intestinal mucosa disruption, which was associated with elevated mucosal antioxidative capacity and improved intestinal barrier functions.
Project description:Continuous supply of high quality onion bulbs to meet year-round demand is dependent on maintaining dormancy and bulb quality during storage. Sprouting impacts negatively on the storage quality of onion bulbs. Ethylene supplementation has previously been revealed to inhibit sprout growth in stored onion bulbs. Fructans content, especially those at higher degree of polymerisation (DP), are reported to positively correlate with delayed sprouting. However, little is known about the impact of pre-harvest irrigation regimes on fructans accumulation and redistribution in relation to onion bulb dormancy and quality in store. Across two seasons, onion plants of cultivars 'Red Baron' and 'Sherpa' were subjected to full irrigation (FI) (100% replenishment of crop evapotranspiration) or deficit irrigation (DI) (50% of FI treatment) from bulb initiation to harvest. Bulbs were harvested at full maturity and stored at 1?°C for five months. Bulbs were treated with or without 1-MCP (1??L?L-1) for 24?h before storage under continuous ethylene supplementation (10??L?L-1) or air. DI had no effect on dormancy-break, sprout emergence, total fructans content and total sugar content. In contrast, ethylene delayed sprout emergence and suppressed sprout growth; added 1-MCP enhanced this effect. The concentration of DP3-8 fructans were higher in top and bottom sections compared to the baseplate. Before sprout emergence, fructans of DPs 7-8 were no longer present in the top and bottom wedges, while they accumulated in the baseplate; irrespective of pre- or postharvest treatments. This redistribution of fructans within the bulb suggested a transition in dormancy state and could be used as a predictive marker for sprouting in stored onion bulbs.
Project description:Valorization of onion peel waste, considered to be a rich source of polyphenolic compounds, by employing green extraction techniques is the need of the hour. The aim of the present study was to optimize the microwave-assisted extraction of bioactive phenolic compounds from onion peel wastes employing ChCl:Urea:H2O deep eutectic solvent. Microwave power (100-200-300 W), time (5-15-25 min) and liquid to solid ratio (40:1-50:1-60:1) were studied as the major parameters affecting the extraction efficiency. A Box-Behnken design was adopted including 17 experiments with five centre points. The optimum conditions determined were 100 W microwave power, 15.03 min irradiation time and 54.97 mL g-1 liquid to solid ratio. Under the MAE optimized conditions, the recovery of TPC and FRAP were 80.45 (mg GAE g-1 dw) and 636.18 (µmol AAE g-1 dw), respectively. Morphology of onion peels before and after DES extraction were also studied to gain an insight in the effect of microwave irradiations on the biomass.
Project description:It was recently shown that, by controlling the O(2) concentration, the seeded-growth of CdSe nanocrystals (NC) can be manipulated to proceed either unidirectionally (from the (0001) facet) or three-dimensionally. In this contribution, we investigate two new Se precursors (i.e. SeO(2) and NaHSe) and compare them with Se obtained from etching of smaller NC seeds. Under anaerobic conditions, both precursors led to successful 3-dimensional (3D) NC growth. At high O(2) concentrations, the seeded growth of rods was enhanced by the NaHSe precursor, while impeded by the use of SeO(2). Mechanistic studies showed that the reduction of SeO(2) to Se(2-) produces an excessive amount of O(2). This leads to rod fragmentation due to etching as well as the production of deep traps that quench their luminescence. These new precursors, along with a heightened understanding of oxygen's role, expand the synthetic repertoire of the redox-assisted, seeded-growth of CdSe and better position this low temperature (125 °C) methodology towards realizing advanced NC heterostructures.
Project description:The electrochemical reduction of CO2 is an attractive strategy towards the mitigation of environmental pollution and production of bulk chemicals as well as fuels by renewables. The bimetallic sulfide Fe4.5 Ni4.5 S8 (pentlandite) was recently reported as a cheap and robust catalyst for electrochemical water splitting, as well as for CO2 reduction with a solvent-dependent product selectivity. Inspired by numerous reports on monometallic sulfoselenides and selenides revealing higher catalytic activity for the CO2 reduction reaction (CO2 RR) than their sulfide counterparts, the authors investigated the influence of stepwise S/Se exchange in seleno-pentlandites Fe4.5 Ni4.5 S8-Y SeY (Y=1-5) and their ability to act as CO2 reducing catalysts. It is demonstrated that the incorporation of higher equivalents of selenium favors the CO2 RR with Fe4.5 Ni4.5 S4 Se4 revealing the highest activity for CO formation. Under galvanostatic conditions in acetonitrile, Fe4.5 Ni4.5 S4 Se4 generates CO with a Faradaic Efficiency close to 100?% at applied current densities of -50?mA?cm-2 and -100?mA?cm-2 . This work offers insight into the tunability of the pentlandite based electrocatalysts for the CO2 reduction reaction.
Project description:Little is known regarding the relationship between Selenium (Se) concentrations in the liver and liver gene expression. Because most cow-calf operations in Se-poor soils provide enough Se in mineral mixes to avoid deficiency, the aim of this study was to determine the effects of 4 Se form supplementation strategies (none or inorganic, organic, or 1:1 inorganic:organic mix) on liver gene expression profiles using a Se-adequate model. Microarray analysis was conducted using the custom WT Btau 4.0 Array (version 1; GeneChip, Affymetrix, Inc., Santa Clara, CA, USA) to determine if dietary Se supplementation form differentially affects the hepatic gene expression profiles of maturing beef heifers. Sodium selenite was used as the source of inorganic Se and Se-enriched yeast was the source of organic selenium. Thirty-six Angus heifers (BW 400 ± 9.0 kg) were ranked on the Se concentration of their biopsied (day -14) liver sample and randomly assigned to one of four dietary Se treatments: Control (Ctrl) group received no exogenous dietary Se supplementation; inorganic (ISe) treatment group received daily dietary Se supplementation at 3 mg/ animal of the ISe form; organic (OSe) treatment group received daily dietary Se supplementation of 3 mg/ animal of OSe form; and the mix (1:1 ISe:OSe) received daily dietary Se supplementation of 3 mg/ animal of 50:50 mix of ISe and OSe forms. RNA was extracted from biopsied liver samples taken 168 days after initiation of Se supplementation and microarray analyses were conducted.