Selenium. Role of the essential metalloid in health

Molecular insights into the bonding mechanisms between selenium and dissolved organic matter

Natural organic matter (NOM) plays a critical role in the mobilization and bioavailability of metals and metalloids in the aquatic environment. Selenium (Se), an environmental contaminant of aquatic systems, has drawn increasing attention over the years. While Se is a vital micronutrient to human beings, animals and plants, excess Se intake may pose serious long-term risks. However, the interaction between Se and dissolved organic matter (DOM) remains relatively unexplored, especially the reaction mechanisms and interactions of specific NOM components of certain molecular weight and the corresponding functional group change. Herein, we report an investigation on the interactions between Se and DOM by focusing on the mass distribution profile change of operationally defined molecular weight fractions of humic acid (HA) and fulvic acid (FA). The results showed that across all molecular weights studied, HA fractions were more prone to enhanced aggregation upon introduction of Se into the system. For FA, the presence of Se species results in aggregation, dissociation, and redox reactions with the first two being the major mechanisms. Total organic carbon analysis (TOC), UV-vis spectroscopy (UV-vis), and Orbitrap MS data showed that [10, 30] kDa MW fraction had the largest aromatic decrease (CRAM-like, lignin-like and tannin-like) upon addition of SeO2 via dissociation as the dominant mechanism. Fourier transform infrared spectroscopy (FT-IR) revealed that Se based bridging or chelation of functional groups from individual DOM components through hydrogen bonding in the form of SeO⋯H and possibly Se⋯H and/or attractive electrostatic interactions lead to aggregated DOM1⋯Se⋯DOM2. It was concluded from two-dimensional correlation analyses of excitation emission matrix (EEM) and FT-IR that the preferred Se-binding follows lipid ➔ peptide ➔ tannin ➔ aromatic functionalities. These results provide new understanding of Se interactions with various NOM components in aquatic environments and provide insight for Se assessing health risk and/or treatment of Se contaminated water.

Relative bioavailability of selenium in rice using a rat model and its application to human health risk assessment

Deficiencies of selenium (Se), a necessary microelement for humans, can be remedied by appropriately supplying Se-enriched rice. However, overconsumption of Se-enriched rice poses a potential risk. To accurately assess Se human health risks associated with Se-enriched rice consumption, we developed a rat in vivo model to systematically explore the relative bioavailability of Se (Se-RBA) from Se-enriched rice from a wide geographic range. Se concentrations were in the range of 0.06 ± 0.05 to 0.15 ± 0.15 mg kg-1, averaging 0.12 ± 0.11 mg kg-1, in 196 rice samples from 21 Chinese provinces, and selenomethionine (SeMet) was the dominant Se fraction (58.0-96.5%). The Se-RBA of Se-enriched rice calculated from urine ranged from 34.86% to 102.29%, averaging 62.27% (n = 12), and was positively correlated with the proportion of SeMet in rice (p < 0.05, R2 = 0.51). Furthermore, the Se intake calculated based on the Se-RBA indicated that the Se intake of consumers of Se-enriched rice was far less than the tolerable upper intake level. Thus, the limits established by law assume overestimates of the actual nutritional value of the Se content in Se-enriched rice, and it is important to consider Se bioavailability. The current study offers suggestions for future research and provides methods to reduce the uncertainty in estimating the health risks associated with Se intake from rice.

Co-exposure to iron, copper, zinc, selenium and titanium is associated with the prevention of gastric precancerous lesions

Gastric cancer is the third leading cause of cancer death, and gastric precancerous lesions (GPLs) are an important stage in the transformation of normal gastric mucosa to gastric cancer. Matched for age and sex, a total of 316 subjects were eventually included from our prospective observation population (including 1007 patients with GPLs and 762 normal controls), and a questionnaire survey was conducted. In total, 10 plasma elements (iron, copper, zinc, selenium, rubidium, strontium, titanium, aluminum, vanadium and arsenic) were measured by applying inductively coupled plasma‒mass spectrometry (ICP‒MS). A multivariate conditional logistic regression model and Bayesian kernel logistic regression model (BKMR) were used to analyze the association between plasma element concentrations and GPLs. In the multimetal model, plasma titanium concentrations were significantly and positively associated with the prevalence of GPLs, with a fourth-quartile OR of 11.56 ([95% CI]: [2.78-48.13]). Plasma selenium and copper were negatively correlated with GPLs, with the highest quartiles of selenium and copper having an OR of 0.03 ([95% CI]: [0.01-0.15]; P < 0.001) and 0.24 ([95% CI]: [0.07-0.82]), respectively. In the BKMR model, there was a significant negative combined correlation of five metals on GPLs: iron, copper, zinc, selenium, and titanium. The results of this study showed that plasma concentrations of selenium and copper were negatively correlated with GPLs, while plasma concentrations of titanium were positively correlated with GPLs, and the combined action of the five elements was negatively correlated with GPLs.

The Ozonolysis of Methylated Selenide Compounds in the Atmosphere: Isotopes, Kinetics, Products, and Mechanisms

Selenium (Se) is an essential micronutrient with an important atmospheric component in its biogeochemical cycle. In this cycle, phytoplankton form volatile organic Se species, such as dimethyl selenide (CH3SeCH3) and dimethyl diselenide (CH3SeSeCH3), which are emitted into the atmosphere. To predict the atmospheric fate of these methylated Se compounds, we investigated their ozonolysis reaction. We used proton-transfer-reaction time-of-flight mass spectrometry to quantify atmospheric Se and its isotopes, and used this method in kinetic and product studies. The ozonolysis of CH3SeCH3 proceeded with a rate constant of (7.4 ± 2.2) × 10-17 cm3 molec-1 s-1 at 26 ± 1 °C with an activation energy of 50 ± 14 kJ mol-1 forming dimethyl selenoxide (CH3Se(O)CH3). Comparatively, CH3SeSeCH3 reacted with O3 at (2.6 ± 0.9) × 10-17 cm3 molec-1 s-1 at 27 ± 1 °C with an activation energy of 56 ± 5 kJ mol-1 forming methylselinic acid (CH3Se(O)OH). At 20 ppbv of O3, the atmospheric lifetimes of CH3SeCH3 and CH3SeSeCH3 are 7.6 and 22 h, respectively. The Se oxidation products were confirmed by synthesis and can serve as new atmospheric tracers of methylated Se compounds. Overall, we measured Se isotopes in real time and determined the rate constants, activation energies, and oxidation products. These mechanisms can now be used to determine the quantitative atmospheric fate of Se toward O3, and thus its distribution within a changing climate.

Antimicrobial Activity of Selenium Nanoparticles (SeNPs) against Potentially Pathogenic Oral Microorganisms: A Scoping Review

Biofilms are responsible for the most prevalent oral infections such as caries, periodontal disease, and pulp and periapical lesions, which affect the quality of life of people. Antibiotics have been widely used to treat these conditions as therapeutic and prophylactic compounds. However, due to the emergence of microbial resistance to antibiotics, there is an urgent need to develop and evaluate new antimicrobial agents. This scoping review offers an extensive and detailed synthesis of the potential role of selenium nanoparticles (SeNPs) in combating oral pathogens responsible for causing infectious diseases. A systematic search was conducted up until May 2022, encompassing the MEDLINE, Embase, Scopus, and Lilacs databases. We included studies focused on evaluating the antimicrobial efficacy of SeNPs on planktonic and biofilm forms and their side effects in in vitro studies. The selection process and data extraction were carried out by two researchers independently. A qualitative synthesis of the results was performed. A total of twenty-two articles were considered eligible for this scoping review. Most of the studies reported relevant antimicrobial efficacy against C. albicans, S. mutans, E. faecalis, and P. gingivalis, as well as effective antioxidant activity and limited toxicity. Further research is mandatory to critically assess the effectiveness of this alternative treatment in ex vivo and in vivo settings, with detailed information about SeNPs concentrations employed, their physicochemical properties, and the experimental conditions to provide enough evidence to address the construction and development of well-designed and safe protocols.

Concomitant selenoenzyme inhibitor exposures as etiologic contributors to disease: Implications for preventative medicine

The physiological activities of selenium (Se) occur through enzymes that incorporate selenocysteine (Sec), a rare but important amino acid. The human genome includes 25 genes coding for Sec that employ it to catalyze challenging reactions. Selenoenzymes control thyroid hormones, calcium activities, immune responses, and perform other vital roles, but most are devoted to preventing and reversing oxidative damage. As the most potent intracellular nucleophile (pKa 5.2), Sec is vulnerable to binding by metallic and organic soft electrophiles (E*). These electron poor reactants initially form covalent bonds with nucleophiles such as cysteine (Cys) whose thiol (pKa 8.3) forms adducts which function as suicide substrates for selenoenzymes. These adducts orient E* to interact with Sec and since Se has a higher affinity for E* than sulfur, the E* transfers to Sec and irreversibly inhibits the enzyme's activity. Organic electrophiles have lower Se-binding affinities than metallic E*, but exposure sources are more abundant. Individuals with poor Se status are more vulnerable to the toxic effects of high E* exposures. The relative E*:Se stoichiometries remain undefined, but the aggregate effects of multiple E* exposures are predicted to be additive and possibly synergistic under certain conditions. The potential for the combined Se-binding effects of common pharmaceutical, dietary, or environmental E* require study, but even temporary loss of selenoenzyme activities would accentuate oxidative damage to tissues. As various degenerative diseases are associated with accumulating DNA damage, defining the effects of complementary E* exposures on selenoenzyme activities may enhance the ability of preventative medicine to support healthy aging.

The role of selenoproteins in neurodevelopment and neurological function: Implications in autism spectrum disorder

Selenium and selenoproteins play a role in many biological functions, particularly in brain development and function. This review outlines the role of each class of selenoprotein in human brain function. Most selenoproteins play a large antioxidant role within the brain. Autism spectrum disorder (ASD) has been shown to correlate with increased oxidative stress, and the presumption of selenoproteins as key players in ASD etiology are discussed. Further, current literature surrounding selenium in ASD and selenium supplementation studies are reviewed. Finally, perspectives are given for future directions of selenoprotein research in ASD.

Selenium, Selenoproteins and 10-year Cardiovascular Risk: Results from the ATTICA Study

BACKGROUND

Selenium (Se) is an essential trace element that is involved in several pathophysiological functions. The relationship of Se with cardiovascular disease remains inconclusive, especially regarding the role of different selenospecies.

OBJECTIVE

The present study assessed the levels of Se distribution in plasma selenoproteins, namely glutathione peroxidase 3 (GPx3), selenoprotein P (SelP) and selenoalbumin (SeAlb) and total Se in selenoproteins in relation to 10-year cardiovascular risk in the ATTICA prospective study.

METHODS

A sub-sample from the ATTICA Study's database, consisting of 278 subjects (114 women and 164 men) with data on Se and selenoproteins levels, was considered. SeGPx3, SelP, and SeAlb in human plasma were simultaneously determined by high-performance liquid chromatography (HPLC) coupled with inductively coupled plasma mass spectrometry (ICP-MS) at baseline. The duration of the follow-up was 8.74 ±2.36 years (mean± standard deviation) and cardiovascular outcomes were recorded. Cox proportional hazards models were applied with total Se or selenoprotein Se as independent variables adjusted for several covariates.

RESULTS

Total Se in selenoproteins was positively related to 10-year relative risk of cardiovascular disease (Hazard Ratios of 3rd vs 2nd tertile 10.02, 95% CI:1.15, 92.34). Subjects with high Se but low SeGPx3, as identified by discordant percentiles in the distribution of SeGPx3 and Se, had a higher cardiovascular risk.

CONCLUSION

The differentiated effects of circulating selenoproteins on cardiovascular disease risk in the present study, suggest the importance of redox regulation by specific selenoproteins.

eIF3 Interacts with Selenoprotein mRNAs

The synthesis of selenoproteins requires the co-translational recoding of an in-frame UGASec codon. Interactions between the Selenocysteine Insertion Sequence (SECIS) and the SECIS binding protein 2 (SBP2) in the 3'untranslated region (3'UTR) of selenoprotein mRNAs enable the recruitment of the selenocysteine insertion machinery. Several selenoprotein mRNAs undergo unusual cap hypermethylation and are not recognized by the translation initiation factor 4E (eIF4E) but nevertheless translated. The human eukaryotic translation initiation factor 3 (eIF3), composed of 13 subunits (a-m), can selectively recruit several cellular mRNAs and plays roles in specialized translation initiation. Here, we analyzed the ability of eIF3 to interact with selenoprotein mRNAs. By combining ribonucleoprotein immunoprecipitation (RNP IP) in vivo and in vitro with cross-linking experiments, we found interactions between eIF3 and a subgroup of selenoprotein mRNAs. We showed that eIF3 preferentially interacts with hypermethylated capped selenoprotein mRNAs rather than m⁷G-capped mRNAs. We identified direct contacts between GPx1 mRNA and eIF3 c, d, and e subunits and showed the existence of common interaction patterns for all hypermethylated capped selenoprotein mRNAs. Differential interactions of eIF3 with selenoprotein mRNAs may trigger specific translation pathways independent of eIF4E. eIF3 could represent a new player in the translation regulation and hierarchy of selenoprotein expression.

Selenium protects against cadmium-induced cardiac injury by attenuating programmed cell death via PI3K/AKT/PTEN signaling

Cadmium (Cd) is an environmental pollutant that has an enormous influence on agricultural production, but selenium (Se) can alleviate its toxicity. The present study aimed to illustrate the effects of Se on Cd-induced heart injury. All 40 rabbits were randomly divided into four groups: control group, Se [0.5 mg kg^-1 ·body weight (BW)] group, Cd (1 mg kg^-1 ·BW) group, and Se + Cd group. After 30 days of feeding, morphological changes, the levels of oxidative stress and myocardial enzyme, the content of cardiac troponin T, programmed cell death (pyroptosis, autophagy and apoptosis), and PI3K/AKT/PTEN transduction capacity were observed. The results showed that Cd destroyed the physiological balance of trace elements and caused myocardial damage, increased the cardiac oxidative damage and led to programmed cell death. Coadministration of Se prominently ameliorated histological lesions and improved cardiac function of hearts in Cd-induced rabbits. Furthermore, Se exerted detoxification and oxidation resistance, maintained trace element homeostasis, and alleviated the changes of mRNA and protein levels of pyroptosis-, autophagy- and apoptosis-controlling factors and PI3K/AKT/PTEN signal molecules caused by Cd. In conclusion, Se might protect against Cd-induced pyroptosis, autophagy and apoptosis by interfering with PI3K/AKT/PTEN signaling in heart.

Ergothioneine, Ovothiol A, and Selenoneine-Histidine-Derived, Biologically Significant, Trace Global Alkaloids

The history, chemistry, biology, and biosynthesis of the globally occurring histidine-derived alkaloids ergothioneine (10), ovothiol A (11), and selenoneine (12) are reviewed comparatively and their significance to human well-being is discussed.

Prediagnostic Blood Selenium Status and Mortality among Patients with Colorectal Cancer in Western European Populations

A higher selenium (Se) status has been shown to be associated with lower risk for colorectal cancer (CRC), but the importance of Se in survival after CRC diagnosis is not well studied. The associations of prediagnostic circulating Se status (as indicated by serum Se and selenoprotein P (SELENOP) measurements) with overall and CRC-specific mortality were estimated using multivariable Cox proportional hazards regression among 995 CRC cases (515 deaths, 396 from CRC) in the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort. Se and SELENOP serum concentrations were measured on average 46 months before CRC diagnosis. Median follow-up time was 113 months. Participants with Se concentrations in the highest quintile (≥100 µg/L) had a multivariable-adjusted hazard ratio (HR) of 0.73 (95% CI: 0.52-1.02; Ptrend = 0.06) for CRC-specific mortality and 0.77 (95% CI: 0.57-1.03; Ptrend = 0.04) for overall mortality, compared with the lowest quintile (≤67.5 µg/L). Similarly, participants with SELENOP concentrations in the highest (≥5.07 mg/L) compared with the lowest quintile (≤3.53 mg/L) had HRs of 0.89 (95% CI: 0.64-1.24; Ptrend = 0.39) for CRC-specific mortality and 0.83 (95% CI: 0.62-1.11; Ptrend = 0.17) for overall mortality. Higher prediagnostic exposure to Se within an optimal concentration (100-150 µg/L) might be associated with improved survival among CRC patients, although our results were not statistically significant and additional studies are needed to confirm this potential association. Our findings may stimulate further research on selenium's role in survival among CRC patients especially among those residing in geographic regions with suboptimal Se availability.

Anticancer Activity of Selenium Nanoparticles In Vitro Studies

Health systems worldwide consider cancer a disease that causes the highest number of deaths per year. The low efficacy of current cancer therapies has led other areas of science to search for new alternatives, including nanomaterial sciences. Selenium nanoparticles have anticancer activity, as revealed by in vitro tests performed on prostate, breast, cervical, lung, colorectal, and liver cancer cell lines. Studies attribute anticancer activity to the anti-metastatic effect due to the inhibition of migration and invasion processes. The antiproliferative effect is the low expression of molecules such as cyclin D1, cyclin E, and CDK2. In addition to the activation of cell apoptosis by caspase-dependent mechanisms, there is a low expression of anti-apoptotic proteins such as Bcl-2 and a high expression of the apoptotic proteins like Bax and Bad. Other studies attribute anticancer activity to the activation of cell necroptosis, where molecules such as TNF and IRF1 participate. The pharmacological potential of selenium nanoparticles depends primarily on the administered dose, particle size, and chemical composition. Furthermore, several studies have shown that the administration of these nanoparticles is safe due to their low toxicity in non-cancerous cells. In this review, the most relevant antecedents on the anticancer potential of selenium nanoparticles in prostate, breast, cervical, lung, liver, and colorectal cancer cell lines are discussed.

Nutrigenomics and Life Style Facet- A Modulatory Molecular Evidence in Progression of Breast and Colon Cancer with Emerging Importance

Legitimate nutrition assumes a significant role in preventing diseases and, in this way, nutritional interventions establish vital strategies in the area of public health. Nutrigenomics centres on the different genes and diet in an individual and how an individual's genes influence the reaction to bioactive foodstuff. It targets considering the genetic and epigenetic interactions with nutrients to lead to a phenotypic alteration and consequently to metabolism, differentiation, or even apoptosis. Nutrigenomics and lifestyle factors play a vital role in health management and represent an exceptional prospect for the improvement of personalized diets to the individual at risk of developing diseases like cancer. Concerning cancer as a multifactorial genetic ailment, several aspects need to be investigated and analysed. Various perspectives should be researched and examined regarding the development and prognosis of breast and colon cancer. Malignant growth occurrence is anticipated to upsurge in the impending days, and an effective anticipatory strategy is required. The effect of dietary components, basically studied by nutrigenomics, looks at gene expression and molecular mechanisms. It also interrelates bioactive compounds and nutrients because of different 'omics' innovations. Several preclinical investigations demonstrate the pertinent role of nutrigenomics in breast and colon cancer, and change of dietary propensities is conceivably a successful methodology for reducing cancer risk. The connection between the genomic profile of patients with breast or colon cancer and their supplement intake, it is conceivable to imagine an idea of personalized medicine, including nutrition and medicinal services.

Responses of Medicinal and Aromatic Plants to Engineered Nanoparticles

Medicinal and aromatic plants have been used by mankind since ancient times. This is primarily due to their healing effects associated with their specific secondary metabolites (some of which are also used as drugs in modern medicine), or their structures, served as a basis for the development of new effective synthetic drugs. One way to increase the production of these secondary metabolites is to use nanoparticles that act as elicitors. However, depending on the specific particle size, composition, concentration, and route of application, nanoparticles may have several other benefits on medicinal and aromatic plants (e.g., increased plant growth, improved photosynthesis, and overall performance). On the other hand, particularly at applications of high concentrations, they are able to damage plants mechanically, adversely affect morphological and biochemical characteristics of plants, and show cytotoxic and genotoxic effects. This paper provides a comprehensive overview of the beneficial and adverse effects of metal-, metalloid-, and carbon-based nanoparticles on the germination, growth, and biochemical characteristics of a wide range of medicinal and aromatic plants, including the corresponding mechanisms of action. The positive impact of nanopriming and application of nanosized fertilizers on medicinal and aromatic plants is emphasized. Special attention is paid to the effects of various nanoparticles on the production of valuable secondary metabolites in these plants cultivated in hydroponic systems, soil, hairy root, or in vitro cultures. The beneficial impact of nanoparticles on the alleviation of abiotic stresses in medicinal and aromatic plants is also discussed.

The inorganic chemicals that surround us: role of tellurium, selenium and zinc on behavioural functions in mammals

Living organisms live in continuous interaction with its environment. During this process changes in one can induce adaptive responses on the other. Many factors in the environment have been studied with the notorious distinction of been rare or to be of high intensity strength in its interaction with living organisms. However, little attention has been put on some factors that have constant interaction with organisms but usually have low intensity strength, such as the case of the inorganic chemical environment that surrounds us. In this review, the interaction between the chemical element and living organisms is discussed under a theoretical model of interaction between compartments, giving attention to tellurium (Te), zinc (Zn) and selenium (Se) on some cognitive functions in human and animals. After studies in our laboratory of the phenotypic expression of the HSR (Hand Skill Relative) gene in school children community living in geographic zone rich in minerals and mines of La Rioja province, Argentine, where Te was found to be in higher non-toxic concentrations, a translational experimental model to maturing rats exposed to this trace element was made. Te was found to increase some parameters related to locomotion in an open field induced by novelty and exploratory motivation. At the same time, inhibition of lateralized responses, survival responses and social activity was also observed. Some of these changes, particularly those related to lateralization had similarity with that found previously in children of La Rioja province. Discussion of similarities and discrepancies of biologic effects between animals and humans, about the possible meaning of Te and its interaction with Zn and Se with relevance to humans was analyzed.

Beyond the Mind-Serum Trace Element Levels in Schizophrenic Patients: A Systematic Review

The alterations in serum trace element levels are common phenomena observed in patients with different psychiatric conditions such as schizophrenia, autism spectrum disorder, or major depressive disorder. The fluctuations in the trace element concentrations might act as potential diagnostic and prognostic biomarkers of many psychiatric and neurological disorders. This paper aimed to assess the alterations in serum trace element concentrations in patients with a diagnosed schizophrenia. The authors made a systematic review, extracting papers from the PubMed, Web of Science, and Scopus databases according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Among 5009 articles identified through database searching, 59 of them were assessed for eligibility. Ultimately, 33 articles were included in the qualitative synthesis. This review includes the analysis of serum levels of the following trace elements: iron, nickel, molybdenum, phosphorus, lead, chromium, antimony, uranium, magnesium, aluminum, zinc, copper, selenium, calcium, and manganese. Currently, there is no consistency regarding serum trace element levels in schizophrenic patients. Thus, it cannot be considered as a reliable prognostic or diagnostic marker of schizophrenia. However, it can be assumed that altered concentrations of those elements are crucial regarding the onset and exaggeration of either psychotic or negative symptoms or cognitive dysfunctions.

Selenium Deficiency—From Soil to Thyroid Cancer

Selenium (Se) is an essential micronutrient present in human diet, entering in the composition of selenoproteins as selenocysteine (Se-Cys) amino acid. At the thyroid level, these proteins play an important role as antioxidant and in hormone metabolism. Selenoproteins are essential for the balance of redox homeostasis and antioxidant defense of mammalian organisms, while the corresponding imbalance is now recognized as the cause of many diseases including cancer. The food chain is the main source of Se in human body. Dietary intake is strongly correlated with Se content in soil and varies according to several factors such as geology and atmospheric input. Both Se deficiency and toxicity have been associated with adverse health effects. This review synthesizes recent data on the transfer of Se from soil to humans, Se U-shaped deficiency and toxicity uptake effects and particularly the impact of Se deficiency on thyroid cancer.

Human red blood cell uptake and sequestration of arsenite and selenite: Evidence of seleno-bis(S-glutathionyl) arsinium ion formation in human cells

Over 200 million people worldwide are exposed to the human carcinogen, arsenic, in contaminated drinking water. In laboratory animals, arsenic and the essential trace element, selenium, can undergo mutual detoxification through the formation of the seleno-bis(S-glutathionyl) arsinium ion [(GS)₂AsSe]^-, which undergoes biliary and fecal elimination. [(GS)₂AsSe]^-, formed in animal red blood cells (RBCs), sequesters arsenic and selenium, and slows the distribution of both compounds to peripheral tissues susceptible to toxic effects. In human RBCs, the influence of arsenic on selenium accumulation, and vice versa, is largely unknown. The study aims were to characterize arsenite (As^III) and selenite (Se^IV) uptake by human RBCs, to determine if Se^IV and As^III increase the respective accumulation of the other in human RBCs, and ultimately to determine if this occurs through the formation and sequestration of [(GS)₂AsSe]^-. ⁷⁵Se^IV accumulation was temperature and Cl^--dependent, inhibited by 4,4'-diisothiocyanatodihydrostilbene-2,2'-disulfonic acid (H₂DIDS) (IC₅₀ 1 ± 0.2 µM), and approached saturation at 30 µM, suggesting uptake is mediated by the erythrocyte anion-exchanger 1 (AE1 or Band 3, gene SLC4A1). HEK293 cells overexpressing AE1 showed concentration-dependent ⁷⁵Se^IV uptake. ⁷³As^III uptake by human RBCs was temperature-dependent, partly reduced by aquaglyceroporin 3 inhibitors, and not saturated. As^III increased ⁷⁵Se^IV accumulation (in the presence of albumin) and Se^IV increased ⁷³As^III accumulation in human RBCs. Near-edge X-ray absorption spectroscopy revealed the formation of [(GS)₂AsSe]^- in human RBCs exposed to both As^III and Se^IV. The sequestration of [(GS)₂AsSe]^- in human RBCs potentially slows arsenic distribution to susceptible tissues and could reduce arsenic-induced disease.

Synthesis of Novel Selenocyanates and Evaluation of Their Effect in Cultured Mouse Neurons Submitted to Oxidative Stress

Herein, we report the synthesis of novel selenocyanates and assessment of their effect on the oxidative challenge elicited by hydrogen peroxide (H₂O₂) in cultured mouse neurons. First, α-methylene-β-hydroxy esters were prepared as precursors of allylic bromides. A reaction involving the generated bromides and sodium selenocyanate was conducted to produce the desired selenocyanates (3a-f). We next prepared cultures of neurons from 7-day-old mice (n = 36). H₂O₂ (10^-5 M) was added into the culture flasks as an oxidative stress inducer, alone or combined with one of each designed compounds. (PhSe)₂ was used as a positive control. It was carried out assessment of lipid (thiobarbituric acid reactive species, 4-hydroxy-2'-nonenal, 8-isoprostane), DNA (8-hydroxy-2'-deoxyguanosine), and protein (carbonyl) modification parameters. Finally, catalase and superoxide dismutase activities were also evaluated. Among the compounds, 3b, 3d, and 3f exhibited the most pronounced pattern of antioxidant activity, similar to (PhSe)₂. These novel aromatic selenocyanates could be promising to be tried in most sophisticated in vitro studies or even at the preclinical level.

Elemental Content in Pleurotus ostreatus and Cyclocybe cylindracea Mushrooms: Correlations with Concentrations in Cultivation Substrates and Effects on the Production Process

Few data exist about the effect of substrates’ elemental content on the respective concentrations in cultivated mushrooms, on the degradation of lignocellulosics or on production parameters. Sixteen elements (14 metals and 2 metalloids) were measured by inductively coupled plasma mass spectrometry (ICP-MS) in Pleurotus ostreatus and Cyclocybe cylindracea mushrooms, and in their seven cultivation substrates composed of various plant-based residues. Results revealed a high variability in elemental concentration among substrates which generally led to significant differences in the respective mushroom contents. High bioconcentration factors (BCFs) were noted for Cd, Cu, Mg and Zn for both species in all substrates. BCF of each element was variously affected by substrates’ pH, crude composition, and p and K content. Significant positive correlations were demonstrated for Cu, Fe, Mn and Li concentrations vs. a decrease of cellulose and hemicellulose in P. ostreatus substrates, and vs. mushrooms’ biological efficiency. In the case of C. cylindracea, Be, Mg and Mn concentrations were positively correlated with the decrease of hemicellulose in substrates, while a significant positive correlation was also recorded vs. mushroom productivity. Finally, it was found that 15% to 35% of the daily dietary needs in Mg, Se and Zn could be covered by mushroom consumption.

Selenium and Selenoproteins in Adipose Tissue Physiology and Obesity

Selenium (Se) homeostasis is tightly related to carbohydrate and lipid metabolism, but its possible roles in obesity development and in adipocyte metabolism are unclear. The objective of the present study is to review the current data on Se status in obesity and to discuss the interference between Se and selenoprotein metabolism in adipocyte physiology and obesity pathogenesis. The overview and meta-analysis of the studies on blood Se and selenoprotein P (SELENOP) levels, as well as glutathione peroxidase (GPX) activity in obese subjects, have yielded heterogenous and even conflicting results. Laboratory studies demonstrate that Se may modulate preadipocyte proliferation and adipogenic differentiation, and also interfere with insulin signaling, and regulate lipolysis. Knockout models have demonstrated that the selenoprotein machinery, including endoplasmic reticulum-resident selenoproteins together with GPXs and thioredoxin reductases (TXNRDs), are tightly related to adipocyte development and functioning. In conclusion, Se and selenoproteins appear to play an essential role in adipose tissue physiology, although human data are inconsistent. Taken together, these findings do not support the utility of Se supplementation to prevent or alleviate obesity in humans. Further human and laboratory studies are required to elucidate associations between Se metabolism and obesity.

Neuroprotective Properties of Resveratrol and Its Derivatives-Influence on Potential Mechanisms Leading to the Development of Alzheimer's Disease

The lack of effective Alzheimer's disease treatment is becoming a challenge for researchers and prompts numerous attempts to search for and develop better therapeutic solutions. Compounds that affect several routes of the neurodegeneration cascade leading to the development of disease are of particular interest. An example of such substances is resveratrol and its synthetic and natural derivatives, which have gained popularity in recent years and show promise as a possible new therapeutic option in the approach to Alzheimer's disease treatment. In this article, the state of the art evidence on the role of resveratrol (RSV) in neuroprotection is presented; research results are summarized and the importance of resveratrol and its derivatives in the treatment of Alzheimer's disease are underlined. It also focuses on various modifications of the resveratrol molecule that should be taken into account in the design of future research on drugs against Alzheimer's disease.

Effects of different sources and levels of dietary iron and selenium on the postprandial net portal appearance of these minerals in growing pigs

The present study compares the net portal appearance of dietary iron (Fe) and selenium (Se) after meals containing different sources and levels of these minerals. Twelve pigs (55.1 ± 3.7 kg) were used in a cross-over design to assess the 11-h net portal-drained viscera (PDV) flux of serum Fe and Se after ingestion of boluses containing inorganic (I) or organic (O) dietary Fe and Se at industry average (A; 200 and 0.6 mg, respectively) or high (H; 400 and 1.2 mg, respectively) levels. Arterial serum Fe concentrations increased by an average of 158% within 6 h post-meal and gradually decreased thereafter (P < 0.001). Values were greater (P < 0.001) for I than for O until 6 h post-meal and greater (P ≤ 0.001) for A than for H from 4 to 8 h post-meal. For the whole post-prandial period (11 h), arterial serum Fe concentrations tended (P = 0.06) to be greater for I than for O and were lowest for HO (P ≤ 0.03). Net PDV flux of Fe tended to be greater for AI than for AO (P ≥ 0.07). Cumulative appearance of Fe in PDV serum (% of dietary intake) was greater for I than for O (2.43 vs. -0.76%; P = 0.02) and A tended to be greater than H (1.96 vs. -0.29 %; P = 0.09) until 3 h post-meal, but these effects further faded out (P ≥ 0.43). Arterial serum Se concentration decreased for all treatments (average of 7%) from premeal values (P < 0.001), and this was more pronounced for O than for I (P = 0.03). Irrespective of treatment, net PDV flux of Se was positive (different from 0, P ≤ 0.03) during the first 90 min post-meal, decreased to negative minimum values (different from 0, P = 0.03) at 5 h post-meal, and was not different from 0 thereafter (P ≥ 0.11). Cumulative appearance of Se in PDV serum (% of dietary intake) was greater for I than for O (20.0 vs. -3.8%; P = 0.04) only at 45 min post-meal. In conclusion, both dietary Fe and Se absorption are limited to the early post-meal period. Whereas for Fe, the level effect is in accordance with the known negative correlation between its dietary concentration and percentage of intestinal absorption, this was not the case for dietary Se. The postabsorptive availability of dietary I was greater than O for both minerals and, particularly for Fe, at low levels.

The Role of Selenium in Arsenic and Cadmium Toxicity: an Updated Review of Scientific Literature

Arsenic (As) and cadmium (Cd) are elements arousing major public health concerns associated with environmental pollution, high toxicity potential, and carcinogenic nature. However, selenium (Se) at low doses and incorporated into enzymes and proteins has antioxidant properties and protects animals and humans from the risk of various diseases. It also has an exceptionally narrow range between necessary and toxic concentrations, which is a well-known hindrance in its use as a dietary supplement. The present article aims to update and expand the role of Se in As and Cd toxicity discussed in our earlier paper. In general, recent reports show that Se, regardless of its form (as selenite, selenomethionine, nanoSe, or Se from lentils), can reduce As- or Cd-mediated toxicity in the liver, kidney, spleen, brain, or heart in animal models and in cell culture studies. As was suggested in our earlier review, Se antagonizes the toxicity of As and Cd mainly through sequestration of these elements into biologically inert complexes and/or through the action of Se-dependent antioxidant enzymes. An increase in the As methylation efficiency is proposed as a possible mechanism by which Se can reduce As toxicity. However, new studies indicate that Se may also diminish As or Cd toxicity by activation of the Nrf2 pathway. In addition, this paper discusses possible signs of Se toxic effects, which may be a challenge for its future use in the therapy of As and Cd poisoning and provide future directions to address this issue.

In urban, but not rural, areas of Madre de Dios, Peru, adoption of a Western diet is inversely associated with selenium intake

Road development has been a major driver of the transition from traditional to calorie-dense processed 'Western' diets in lower and middle-income countries. The paving of the Interoceanic Highway (IOH) facilitated rapid development to the Madre de Dios (MDD) region in the Peruvian Amazon. As traditional foods such as Brazil nuts and fish are known to be rich in the essential micronutrient selenium, people further along the nutrition transition to a Western diet may have lower selenium (Se) intake. To test this hypothesis, in 2014 the Investigacion de Migracion, Ambiente, y Salud (IMAS Study) (Migration, Environment, and Health Study) collected household surveys from 310 households in 46 communities along the IOH and nails for Se analysis from 418 adults. Principal component analysis of 25 commonly consumed food items identified a factor resembling Western diet, which was used to calculate household Western diet weighted sum factor scores (WSFS). WSFS means were interpolated into a 10 km buffer around the IOH using inverse distance weighting. Western diet adoption was higher in urban compared to rural areas (p < 0.0001), and geographic variation was observed between mining and agricultural areas. Mean nail Se was 730 ng/g, SD 198 ng/g (range: 200-1390 ng/g). Generalized estimating equation (GEE) models assessed the association between food consumption and nail Se. Household chicken consumption was positively associated with Se in rural areas only. Urban/rural status modified the effect of western diet adoption on nail Se, and Se was inversely associated with WSFS in urban areas only. Conclusion: In urban, but not rural, areas of Madre de Dios, Peru, adoption of a Western diet is inversely associated with selenium intake. As the essential micronutrient selenium is a vital part of antioxidant proteins, lower intake could compound the chronic health effects that may result from transition to a calorie-dense diet.

Evaluation of cytotoxicity, biochemical profile and yield components of groundnut plants treated with nano-selenium

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Preparation and Characterization of selenium nanoparticles.

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Foliar application of the prepared nano-selenium on 3 different groundnut (Arachis hypogaea L.) cultivars.

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Evaluation of the effect of nanoselenium on Growth parameters, lipid peroxidation, antioxidants enzymes.

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Evaluation of prepared nano-selenium cytotoxicity.

Knowledge about the risks of the nanoparticles application on the plant development and human health is still limited. Different concentrations of nano-selenium (0, 20 and 40 ppm) were applied to three different Egyptian groundnut (Arachis hypogaea l.) cultivars; (NC, Gregory and Giza 6) under sandy soil conditions at vegetative growth stage to investigate their effects on yield components, protein profile, fatty acids composition, total antioxidant content and cytotoxicity of yielded seeds. The results indicate that the tested Nano-Selenium (Nano-Se) concentrations improved yield components and seeds oil. However, Nano-Se altered protein signatures as well as fatty acids composition by increasing unsaturated fatty acids and/or decreasing saturated fatty acids as compared with control, the cytotoxicity assessments proved safety of the yield for human health.

Selenium, Selenoproteins and Viral Infection

Reactive oxygen species (ROS) are frequently produced during viral infections. Generation of these ROS can be both beneficial and detrimental for many cellular functions. When overwhelming the antioxidant defense system, the excess of ROS induces oxidative stress. Viral infections lead to diseases characterized by a broad spectrum of clinical symptoms, with oxidative stress being one of their hallmarks. In many cases, ROS can, in turn, enhance viral replication leading to an amplification loop. Another important parameter for viral replication and pathogenicity is the nutritional status of the host. Viral infection simultaneously increases the demand for micronutrients and causes their loss, which leads to a deficiency that can be compensated by micronutrient supplementation. Among the nutrients implicated in viral infection, selenium (Se) has an important role in antioxidant defense, redox signaling and redox homeostasis. Most of biological activities of selenium is performed through its incorporation as a rare amino acid selenocysteine in the essential family of selenoproteins. Selenium deficiency, which is the main regulator of selenoprotein expression, has been associated with the pathogenicity of several viruses. In addition, several selenoprotein members, including glutathione peroxidases (GPX), thioredoxin reductases (TXNRD) seemed important in different models of viral replication. Finally, the formal identification of viral selenoproteins in the genome of molluscum contagiosum and fowlpox viruses demonstrated the importance of selenoproteins in viral cycle.

Processive Recoding and Metazoan Evolution of Selenoprotein P: Up to 132 UGAs in Molluscs

Selenoproteins typically contain a single selenocysteine, the 21st amino acid, encoded by a context-redefined UGA. However, human selenoprotein P (SelenoP) has a redox-functioning selenocysteine in its N-terminal domain and nine selenium transporter-functioning selenocysteines in its C-terminal domain. Here we show that diverse SelenoP genes are present across metazoa with highly variable numbers of Sec-UGAs, ranging from a single UGA in certain insects, to 9 in common spider, and up to 132 in bivalve molluscs. SelenoP genes were shaped by a dynamic evolutionary process linked to selenium usage. Gene evolution featured modular expansions of an ancestral multi-Sec domain, which led to particularly Sec-rich SelenoP proteins in many aquatic organisms. We focused on molluscs, and chose Pacific oyster Magallana gigas as experimental model. We show that oyster SelenoP mRNA with 46 UGAs is translated full-length in vivo. Ribosome profiling indicates that selenocysteine specification occurs with ∼5% efficiency at UGA1 and approaches 100% efficiency at distal 3' UGAs. We report genetic elements relevant to its expression, including a leader open reading frame and an RNA structure overlapping the initiation codon that modulates ribosome progression in a selenium-dependent manner. Unlike their mammalian counterparts, the two SECIS elements in oyster SelenoP (3'UTR recoding elements) do not show functional differentiation in vitro. Oysters can increase their tissue selenium level up to 50-fold upon supplementation, which also results in extensive changes in selenoprotein expression.

Selenium cytotoxicity in Tetrahymena thermophila: New clues about its biological effects and cellular resistance mechanisms

Selenium is an essential micronutrient but at high concentrations can produce severe cytotoxicity and genomic damage. We have evaluated the cytotoxicity, ultrastructural and mitochondrial alterations of the two main selenium inorganic species; selenite and selenate, in the eukaryotic microorganism Tetrahymena thermophila. In this ciliate, selenite is more toxic than selenate. Their LC₅₀ values were calculated as 27.65 μM for Se(IV) and 56.88 mM for Se(VI). Significant levels of peroxides/hydroperoxides are induced under low-moderate selenite or selenate concentrations. Se(VI) exposures induce an immediate mitochondrial membrane depolarization. Selenium treated cells show an intense vacuolization and some of them present numerous discrete and small electrondense particles, probably selenium deposits. Mitochondrial fusion, an intense swelling in peripheral mitochondria and mitophagy are detected in selenium treated cells, especially in those exposed to Se (IV). qRT-PCR analysis of diverse genes, encoding relevant antioxidant enzymes or other proteins, like metallothioneins, involved in an environmental general stress response, have shown that they may be crucial against Se(IV) and/or Se (VI) cytotoxicity.

Role of Key Micronutrients from Nutrigenetic and Nutrigenomic Perspectives in Cancer Prevention

Regarding cancer as a genetic multi-factorial disease, a number of aspects need to be investigated and analyzed in terms of cancer's predisposition, development and prognosis. One of these multi-dimensional factors, which has gained increased attention in the oncological field due to its unelucidated role in risk assessment for cancer, is diet. Moreover, as studies advance, a clearer connection between diet and the molecular alteration of patients is becoming identifiable and quantifiable, thereby replacing the old general view associating specific phenotypical changes with the differential intake of nutrients. Respectively, there are two major fields concentrated on the interrelation between genome and diet: nutrigenetics and nutrigenomics. Nutrigenetics studies the effects of nutrition at the gene level, whereas nutrigenomics studies the effect of nutrients on genome and transcriptome patterns. By precisely evaluating the interaction between the genomic profile of patients and their nutrient intake, it is possible to envision a concept of personalized medicine encompassing nutrition and health care. The list of nutrients that could have an inhibitory effect on cancer development is quite extensive, with evidence in the scientific literature. The administration of these nutrients showed significant results in vitro and in vivo regarding cancer inhibition, although more studies regarding administration in effective doses in actual patients need to be done.

The bio-relevant metals of the periodic table of the elements

The bio-relevant metals (and derived compounds) of the Periodic Table of the Elements (PTE) are in the focus. The bulk elements sodium (Na), potassium (K), magnesium (Mg), and calcium (Ca) from the s-block, which are essential for all kingdoms of life, and some of their bio-activities are discussed. The trace elements of the d-block of the PTE as far as they are essential for humans (Mn, Fe, Co, Cu, Zn, Mo) are emphasized, but V, Ni, Cd, and W, which are essential only for some forms of life, are also considered. Chromium is no longer classified as being essential. From the p-block metals only the metalloid (half-metal) selenium (Se) is essential for all forms of life. Two other metalloids, silicon and arsenic, are briefly mentioned, but they have not been proven as being essential for humans. All metals of the PTE and a plethora of their compounds are used in industry and many of them are highly toxic, like lead (Pb), which is discussed as a prime example. Several metals of the PTE, that is, their ions and complexes, are employed in medicine and we discuss the role of lithium, gallium, strontium, technetium, silver, gadolinium (the only f-block element), platinum, and gold.

Urinary concentrations of environmental metals and associating factors in pregnant women

Pregnant women, a vulnerable population, can be exposed to a variety of environmental metals that may adversely affect their health at elevated concentrations. Moreover, environmental exposure and risk disparities are associated with several factors such as sociodemographic characteristics, pregnancy complications, and nutritional supplementation indicators. Our aim was to investigate whether and how the urinary metal concentrations vary according to these factors in a large pregnancy and birth cohort. Urinary levels of seven metals including manganese, zinc, selenium, arsenic, cadmium, thallium, and lead were assessed in 7359 participants across Wuhan City in China. In all, 7359 urine samples from the third trimester were analyzed and 15 sociodemographic characteristics, pregnancy complications, and nutritional supplementation indicators were assessed: maternal age, household income, multivitamin supplements during pregnancy, etc. Concentrations of Zn, As, and Cd were detected in all urine samples; Mn, Se, Tl, and Pb were detected in 95.3%, 99.8%, 99.8%, and 99.9% urine samples, respectively. The geometric mean (GM) of creatinine-adjusted urinary Mn, Zn, Se, As, Cd, Tl, and Pb concentrations were 1.42, 505.44, 18.24, 30.49, 0.64, 0.55, and 3.69 μg/g. Factors that associated with environmental metals concentration were as follows: (1) Urinary Zn and Cd concentrations increased with maternal age. (2) Pregnant women with higher education had lower Cd concentrations. (3) Pregnant women with folic acid supplementation had lower Mn and with multivitamin supplementation had higher Se and lower Tl. Our results demonstrated that the maternal age, education level, folic acid supplementation, and multivitamin supplementation were significantly associated with environmental metal concentrations. Furthermore, studies are recommended to explore the influence of diet on biological metals concentrations in more detail.

Tellurium epigenetic transgenerational effects on behavioral expression of coping behavior in rats

An increasing interest has been developed in the past 15 years in the relationship between trace elements and cell functioning. In the present work the possibility of transgenerational effects of Te was investigated in rats. F₁ generation exposed to K₂TeO₃ (1.55nM) from day 1 of pregnancy until litters were 30 day old, these animals with no other treatment than tap water and food were let to reach 60-70 day old. At this age, female rats were mated with normal untreated male rats. The F₂ generation also without any Te treatment was allowed to grow until 30 days of age. At this age, behavioral tests measuring exploration induced by novelty, lateralized exploration, social interaction and survival behavior were applied. Results showed that head-dipping, rearing, lateralized exploration, social interaction, and survival behaviors, affected by Te treatment in F₁ generation, also were modified in the same manner in F₂ generation. These data show that Te effects on coping behavior in rats are preserved epigenetically in the next generation.

The selenocyanate dimer radical anion in water: Transient Raman spectra, structure, and reaction dynamics

The selenocyanate dimer radical anion (SeCN)₂ ^•-, prepared by electron pulse irradiation of selenocyanate anion (SeCN)^- in water, has been examined by transient absorption, time-resolved Raman spectra, and range-separated hybrid density functional (ωB97x and LC-ωPBE) theory. The Raman spectrum, excited in resonance with the 450 nm (λ_max) absorption of the radical, is dominated by a very strong band at 140.5 cm^-1, associated with the Se-Se stretching vibration, its overtones and combinations. A striking feature of the (SeCN)₂ ^•- Raman spectrum is the relative sharpness of the 140.5 cm^-1 band compared to the S-S band at 220 cm^-1 in thiocyanate radical anion (SCN)₂ ^•-, the difference of which is explained in terms of a time-averaged site effect. Calculations, which reproduce experimental frequencies fairly well, predict a molecular geometry with the SeSe bond length of 2.917 (±0.04) Å, the SeC bond length of 1.819 (±0.004) Å, and the CN bond length of 1.155 (±0.002) Å. An anharmonicity of 0.44 cm^-1 has been determined for the 140.5 cm^-1 Se-Se vibration which led to a dissociation energy of ∼1.4 eV for the SeSe bond, using the Morse potential in a diatomic approximation. This value, estimated for the radical confined in a solvent cage, compares well with the calculated gas-phase energy, 1.32 ± 0.04 eV, required for the radical to dissociate into (SeCN)^• and (SeCN)^- fragments. The enthalpy of dissociation in water has been measured (0.36 eV) and compared with the value estimated by accounting for the solvent dielectric effects in structural calculations.

Consequences of mutations and inborn errors of selenoprotein biosynthesis and functions

In its 200 years of history, selenium has been defined first as a toxic element and finally as a micronutrient. Selenium is incorporated into selenoproteins as selenocysteine (Sec), the 21st proteinogenic amino acid codified by a stop codon. Specific biosynthetic factors recode UGA stop codon as Sec. The significance of selenoproteins in human health is manifested through the identification of patients with inborn errors in selenoproteins or their biosynthetic factors. Selenoprotein N-related myopathy was the first disease identified due to mutations in a selenoprotein gene. Mutations in GPX4 were linked to Sedaghatian disease, characterized by bone and brain anomalies and cardiorespiratory failure. Mutations in TXNRD2 produced familial glucocorticoid deficiency (FGD) and dilated cardiomyopathy (DCM). Genetic generalized epilepsy was associated with mutations in TXNRD1 gene. Mutations in biosynthetic factors as SEPSECS, SECISBP2 and even tRNA^[Ser]Sec, have been also related to diseases. Thus, SEPSECS mutations produce a neurodegenerative disease called now pontocerebellar hypoplasia type 2D (PCH2D). SECISBP2 syndrome, caused by SECISBP2 mutations, is a multifactorial disease affecting mainly thyroid metabolism, bone, inner ear and muscle. Similar symptoms were reproduced in a patient carrying a mutation in tRNA^[Ser]Sec gene, TRU-TCA1-1. This review describes human genetic disorders caused by selenoprotein deficiency. Human phenotypes will be compared with mouse models to explain the pathologic mechanisms of lack of selenoproteins.

Maternal Selenium Supplementation Enhanced Skeletal Muscle Development Through Increasing Protein Synthesis and SelW mRNA Levels of their Offspring

The present study aimed to investigate the influence of maternal selenium supplementation on the skeletal muscle development of the offspring. A total of 720 Ross 308 broiler breeders at 24-week-old were allocated into 3 treatments with 6 replicates of 40 hens each and fed with 0 mg/kg-(group Se/C), 0.5 mg/kg organic-(group Se/O), and 0.5 mg/kg inorganic-(group Se/I) selenium, respectively for 8 weeks. The male offspring from each nutritional treatment were divided and housed into 8 cages of 12 birds each and fed with a commercial diet supplemented with selenium from Na₂SeO₃ at 0.15 mg/kg. Results showed that Se/O group had the highest selenium deposition (P < 0.05) in the egg yolk and albumen. Furthermore, maternal selenium supplementation promoted breast muscle yield; increased serum insulin and IGF-I concentration; upregulated AKT, mammalian target of rapamycin (mTOR), P70S6K, Myf5, MyoD, MyoG, and SelW mRNA levels; and improved the phosphorylation of AKT at Serine 473 residue, mTOR at Serine 2448 residue, and FOXO at Serine 256 residue in skeletal muscles of the offspring. In contrast, the hens' diet supplemented with selenium could result in reduction of uric acid level in serum and downregulation of Atrogin-1 and MuRF1 mRNA levels in the skeletal muscle of the offspring. Additionally, no significant effect on the skeletal muscle development post-hatch was observed between organic and inorganic selenium supplementation. In conclusion, maternal organic selenium supplementation improved selenium deposition in egg; however, no significant effect has been detected on the breast muscle development of the offspring of broiler breeder compared with inorganic selenium supplementation.

Comparison of the effects of selenomethionine and selenium-enriched yeast in the triple-transgenic mouse model of Alzheimer's disease

Alzheimer's disease (AD) is a complex, multifactorial neurodegenerative disease that exhibits multiple pathogeneses and heterogeneity. Selenium (Se) is an essential trace element for human and animal nutrition. It has been shown that supplementation with two organic forms of Se, Se-enriched yeast (Se-yeast) and selenomethionine (Se-Met), could improve cognitive impairment, reverse synaptic deficits and mitigate tau pathology in triple-transgenic (3× Tg) AD mice. Se-yeast is well known for its high Se-Met content, which may mediate its anti-AD effects. In addition, a large amount of the physiological and biochemical mechanisms of these two Se drugs in the amelioration AD pathology remains unknown. In this study, the content of Se-yeast aside from Se was analyzed, and the effects of Se-Met and Se-yeast on 3× Tg-AD mice were investigated and compared. The results showed that both Se-Met and Se-yeast not only significantly increased the Se levels, enhanced the antioxidant capacity and improved the cognitive decline in the model, but also decreased the Aβ and tau pathologies in the brain tissue of the AD mice. Moreover, the ability of Se-Met to increase the Se levels in different tissues of the AD mice was more significant than that of Se-yeast. However, the positive effect of Se-yeast on improving the cognitive ability of the AD mice was better than that of Se-Met, likely due to the various elements, vitamins and other nutrients in Se-yeast. Collectively, these results suggest that Se-yeast has potential as a clinical health product or drug for AD but that Se-Met, as a pure organic Se compound, is more suitable for studying the therapeutic mechanism of Se because of its comprehensive effects on AD.

C. elegans-An Emerging Model to Study Metal-Induced RAGE-Related Pathologies

The receptor for advanced glycation end products (RAGE), a multi-ligand receptor, is mostly associated with promoting inflammation and oxidative stress. In addition to advanced glycation end products (AGEs), its ligands include High mobility group box 1 protein (HMGB-1), S-100 proteins and beta-sheet fibrils. The effects of several metals and metalloids on RAGE expression and activation have been recently studied: in vivo and in vitro exposure to methylmercury, selenium, zinc, manganese, and arsenic was associated with a variety of RAGE-related alterations and behavioral impairments, which are mostly dependent upon the administration procedure (local vs. systemic) and age during exposure. Recently, C. elegans has been proposed as a potential novel model for studying RAGE-related pathologies; preliminary data regarding such model and its potential contribution to the study of metal-induced RAGE-related pathologies are discussed.

Concentrations of Trace Elements and Clinical Outcomes in Hemodialysis Patients: A Prospective Cohort Study

BACKGROUND AND OBJECTIVES

Deficiency of essential trace elements and excess of potentially toxic trace elements are common in patients on hemodialysis. Whether these abnormalities are associated with poor outcomes is unknown but worth investigating, because they are potentially treatable.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We did a prospective longitudinal study of 1278 patients on incident hemodialysis, assessing blood concentrations of 25 trace elements at baseline. We used adjusted logistic regression to evaluate the association between trace element status and four outcomes (death, cardiovascular events, systemic infection, and hospitalization). A priori hypotheses concerned (1) deficiency of zinc, selenium, and manganese and (2) excess of lead, arsenic, and mercury. Concentrations of the other 19 elements were tested in hypothesis-generating analyses.

RESULTS

Over 2 years of follow-up, 260 (20%) patients died, 285 (24%) experienced a cardiovascular event, 117 (10%) were hospitalized for systemic infection, and 928 (77%) were hospitalized for any cause. Lower concentrations of zinc or manganese and higher concentrations of lead, arsenic, or mercury were not independently associated with higher risk of clinical outcomes. Lower concentrations of selenium were strongly and independently associated with death (odds ratio, 0.86 per decile; 99.2% confidence interval, 0.80 to 0.93) and all-cause hospitalization (odds ratio, 0.92 per decile; 99.2% confidence interval, 0.86 to 0.98). In exploratory analyses, higher copper concentrations were significantly associated with higher risk of death (odds ratio, 1.07 per decile; 99.2% confidence interval, 1.00 to 1.15), and cadmium levels in the highest decile were associated with higher risk of death (odds ratio, 1.89; 99.2% confidence interval, 1.06 to 3.38).

CONCLUSIONS

Lower levels of zinc or manganese and higher concentrations of lead, arsenic, or mercury were not associated with higher risk of clinical outcomes, but lower concentrations of selenium were strongly and independently associated with the risks of death and hospitalization.

Selenium-regulated hierarchy of human selenoproteome in cancerous and immortalized cells lines

BACKGROUND

Selenoproteins (25 genes in human) co-translationally incorporate selenocysteine using a UGA codon, normally used as a stop signal. The human selenoproteome is primarily regulated by selenium bioavailability with a tissue-specific hierarchy.

METHODS

We investigated the hierarchy of selenoprotein expression in response to selenium concentration variation in four cell lines originating from kidney (HEK293, immortalized), prostate (LNCaP, cancer), skin (HaCaT, immortalized) and liver (HepG2, cancer), using complementary analytical methods. We performed (i) enzymatic activity, (ii) RT-qPCR, (iii) immuno-detection, (iv) selenium-specific mass spectrometric detection after non-radioactive ⁷⁶Se labeling of selenoproteins, and (v) luciferase-based reporter constructs in various cell extracts.

RESULTS

We characterized cell-line specific alterations of the selenoproteome in response to selenium variation that, in most of the cases, resulted from a translational control of gene expression. We established that UGA-selenocysteine recoding efficiency, which depends on the nature of the SECIS element, dictates the response to selenium variation.

CONCLUSIONS

We characterized that selenoprotein hierarchy is cell-line specific with conserved features. This analysis should be done prior to any experiments in a novel cell line.

GENERAL SIGNIFICANCE

We reported a strategy based on complementary methods to evaluate selenoproteome regulation in human cells in culture.

The effect of dietary selenium addition on the concentrations of heavy metals in the tissues of fallow deer (Dama dama L.) in Croatia

The aim of this research was to determine the concentrations of cadmium, lead, mercury, and arsenic and the essential elements iron and selenium in the tissues (muscle, kidney, liver, spleen, and fat) of fallow deer (Dama dama L.) without and with supplemental selenium addition. Another aim was to determine the effect of selenium addition on the indicators of oxidative stress, namely, the levels of superoxide dismutase, glutathione peroxidase, glutathione, and vitamin E. The research was carried out with 40 fallow deer during two research periods. Supplemental feed without selenium addition was provided during the first research period, and supplemental feed with added selenium (3 mg/kg) was provided for 60 days during the second research period. The concentration of selenium in tissues was higher in the second research period than in the first research period (in kidney tissue, 0.957 vs. 0.688 mg/kg, P < 0.05). The dietary addition of selenium decreased (P < 0.05) the concentrations of some heavy metals (lead in the spleen = 0.06 vs. 0.27 mg/kg and in the fatty tissue = 0.17 vs. 0.69 mg/kg; arsenic in the muscle tissue = 0.005 vs. 0.014 mg/kg, liver = 0.003 vs. 0.009 mg/kg, spleen = 0.004 vs. 0.013 mg/kg, and fat = 0.008 vs. 0.016 mg/kg). The activity of glutathione peroxidase was significantly higher (P < 0.05) in the second research period than in the first research period (1375.36 vs. 933.23 U/L).

Trace Elements and Healthcare: A Bioinformatics Perspective

Biological trace elements are essential for human health. Imbalance in trace element metabolism and homeostasis may play an important role in a variety of diseases and disorders. While the majority of previous researches focused on experimental verification of genes involved in trace element metabolism and those encoding trace element-dependent proteins, bioinformatics study on trace elements is relatively rare and still at the starting stage. This chapter offers an overview of recent progress in bioinformatics analyses of trace element utilization, metabolism, and function, especially comparative genomics of several important metals. The relationship between individual elements and several diseases based on recent large-scale systematic studies such as genome-wide association studies and case-control studies is discussed. Lastly, developments of ionomics and its recent application in human health are also introduced.

Methionine and seleno-methionine type peptide and peptoid building blocks synthesized by five-component five-center reactions

A first example of 5-component 5-center reactions with isonitriles [Ugi-5CRs] is described. The extended Ugi type reactions involve selenoaldehydes as well as ammonia, both challenging reactants in multicomponent (MCR) systems, to generate methionine and Se-methionine moieties and derivatives as protected building blocks or for direct ligation in peptides or peptoids. The peptoid/peptide building blocks proved to be non-cytotoxic but increased the expression of genes encoding for stress protective selenoproteins (Gpx1).

Long-Term Excessive Selenium Supplementation Induces Hypertension in Rats

Selenium (Se) is an essential trace element involved in several biological pathways, naturally found in rocks, soils, and food. Even though the daily requirement of Se is achieved through a balanced diet, the use of Se supplements has been frequent. Due to the risk of toxic effects of having Se in excess, supplementation is still under debate. The aim was to evaluate the effects of long-term Se supplementation upon systolic blood pressure (SBP) and redox status of rats exposed to sodium selenite. Male Wistar rats were exposed to 2 and 6 mg/L of sodium selenite in drinking water for 85 days. SBP and body weight were evaluated weekly; oxidative stress biomarkers were measured in blood or plasma; and Se levels were assessed in blood, plasma, kidney, and liver. Se supplementation (2 and 6 mg/L) induced significant increase in the SBP in rats from the 42nd day until the end of the study. This increase on SBP was not associated with significant changes in oxidative stress biomarkers. A significant increase in Se levels was found in whole blood, kidney, and liver from both groups of rats receiving Se supplementation when compared to control. Although the exact mechanisms underlying this augment in SBP are not clear, they are potentially related to other Se biological routes besides the synthesis of selenoproteins, such as GSH-Px. Due to the negative effects upon blood pressure, precautionary measures are advised, since the selling of supplements does not require a medical prescription.