Observations on the levels of total mercury (Hg) and selenium (Se) in species common to the artisanal fisheries of Seychelles

Exposure to mercury (Hg) in Seychelles is expected to be high owing to the large amounts of fish regularly consumed. In spite of this consumption, a recent long-term study of child development found no evidence that higher prenatal exposure to Hg increases the risk of neurological disorders. To identify the major sources of mercury in the diets of Seychellois fish consumers, 16 species of fish common to local markets were tested for total Hg. Selenium (Se), which may act as an antidote to Hg toxicity, was also measured. Mercury and selenium were measured using standardised laboratory procedures. The average total Hg concentration across all species was 0.07 mg/kg while the Se concentrations averaged 0.29 mg/kg. Based on the pooled species dataset, there was no correlation between total Hg and Se concentrations, suggesting that joint bioaccumulation of these elements does not occur in the reef fishes tested. Barracuda (Sphyraena jello) had the highest concentration of Hg (0.36 mg/kg), a level that was below European Union guidelines. Although Seychellois traditionally eat a large amount of fish, barracuda would need to be consumed more than 5 times a week for FAO/WHO Total Hg Provisional Tolerable Weekly Intake (PTWI) limits to be exceeded, an unusual rate of consumption. Further investigations are needed to assess the risks posed to the population through the consumption of marine fish and fish products.     

A Review of Dietary Selenium Intake and Selenium Status in Europe and the Middle East

This is a systematic review of existing data on dietary selenium (Se) intake and status for various population groups in Europe (including the United Kingdom (UK)) and the Middle East. It includes English language systematic reviews, meta-analyses, randomised controlled trials, cohort studies, cross-sectional and case-control studies obtained through PUBMED searches from January, 2002, to November, 2014, for European data and from 1990 to November 2014, for Middle Eastern data. Reports were selected if they included data on Se intake and status. The search identified 19 European/UK studies and 15 investigations in the Middle East that reported Se intake and Se concentration in water and/or food and 48 European/UK studies and 44 investigations in the Middle East reporting Se status. Suboptimal Se status was reported to be widespread throughout Europe, the UK and the Middle East, and these results agreed with previous reports highlighting the problem. Eastern European countries had lower Se intake than Western European countries. Middle Eastern studies provided varying results, possibly due to varying food habits and imports in different regions and within differing socioeconomic groups. In conclusion, Se intake and status is suboptimal in European and Middle Eastern countries, with less consistency in the Middle East.     

Selenium and Chronic Diseases: A Nutritional Genomics Perspective

Mechanistic data have revealed a key role for selenium (Se) and selenoproteins in biological pathways known to be altered in multifactorial diseases, such as cellular maintenance, response to oxidative stress and correct protein folding. Although epidemiological studies indicate that low Se intake is linked to increased risk for various chronic diseases, supplementation trials have given confusing outcomes, suggesting that additional genetic factors could affect the relationship between Se and health. Genetic data support this hypothesis, as risk for several chronic diseases, in particular cancer, was linked to a number of single nucleotide polymorphisms (SNP) altering Se metabolism, selenoprotein synthesis or activity. Interactions between SNPs in selenoprotein genes, SNPs in related molecular pathways and biomarkers of Se status were found to further modulate the genetic risk carried by the SNPs. Taken together, nutritional genomics approaches uncovered the potential implication of some selenoproteins as well as the influence of complex interactions between genetic variants and Se status in the aetiology of several chronic diseases. This review discusses the results from these genetic associations in the context of selenoprotein functions and epidemiological investigations and emphasises the need to assess in future studies the combined contribution of Se status, environmental stress, and multiple or individual SNPs to disease risk.     

Dietary Selenium Levels Affect Selenoprotein Expression and Support the Interferon-γ and IL-6 Immune Response Pathways in Mice

Selenium is an essential element that is required to support a number of cellular functions and biochemical pathways. The objective of this study was to examine the effects of reduced dietary selenium levels on gene expression to assess changes in expression of non-selenoprotein genes that may contribute to the physiological consequences of selenium deficiency. Mice were fed diets that were either deficient in selenium or supplemented with selenium in the form of sodium selenite for six weeks. Differences in liver mRNA expression and translation were measured using a combination of ribosome profiling, RNA-Seq, microarrays, and qPCR. Expression levels and translation of mRNAs encoding stress-related selenoproteins were shown to be up-regulated by increased selenium status, as were genes involved in inflammation and response to interferon-γ. Changes in serum cytokine levels were measured which confirmed that interferon-γ, as well as IL-6, were increased in selenium adequate mice. Finally, microarray and qPCR analysis of lung tissue demonstrated that the selenium effects on immune function are not limited to liver. These data are consistent with previous reports indicating that adequate selenium levels can support beneficial immune responses, and further identify the IL-6 and interferon-γ pathways as being responsive to dietary selenium intake.     

白芍总苷联合硒酵母对Graves病患者促甲状腺激素受体抗体水平及突眼度的影响

目的 观察白芍总苷联合硒酵母对Graves病患者促甲状腺激素受体抗体(TRAb)水平及突眼度的影响.方法 选取本院内分泌科门诊2019年10月至2020年2月收治的90例Graves患者为研究对象,按随机数字表法将其分为对照组、治疗组1、治疗组2,各30例.三组均予以甲巯咪唑治疗,治疗组1在此基础上加用硒酵母治疗,治疗组2在治疗组1基础上加用白芍总苷治疗.比较三组治疗前及治疗3、6个月后的甲状腺功能指标,治疗前与治疗6个月后的左、右眼突眼度差值,治疗6个月后甲巯咪唑的使用总量及不良反应发生情况.结果 治疗前,三组患者的FT3、FT4、TSH、T3、T4、TRAb水平比较,差异无统计学意义(P>0.05);治疗3、6个月后,三组患者的FT3、FT4、T3、T4、TRAb水平均低于治疗前,TSH水平均高于治疗前,差异具有统计学意义(P<0.01);治疗3、6个月后,治疗组1、治疗组2的FT3、FT4、T3、T4、TRAb水平均低于对照组,且治疗组2低于治疗组1,差异具有统计学意义(P<0.05);治疗3、6个月后,治疗组1、治疗组2的TSH水平均高于对照组,且治疗组2高于治疗组1,差异具有统计学意义(P<0.05).治疗组2治疗前与治疗6个月后的左、右眼突眼度差值均低于对照组、治疗组1,治疗6个月后甲巯咪唑的使用总量少于对照组、治疗组1,差异具有统计学意义(P<0.05).三组治疗期间的不良反应总发生率比较,差异无统计学意义(P>0.05).结论 白芍总苷联合硒酵母治疗Graves病能降低患者的TRAb水平,延缓突眼的发展,减少甲巯咪唑的使用总量,提高抑制甲状腺激素的效果,改善症状,值得临床推广应用.     

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目的观察不同硒水平作用的大鼠牙齿脱矿情况,探讨硒与龋易感性的关系。方法2013年8月至10月于吉林大学口腔医学院将12只妊娠Wistar大鼠按体重随机分为4组,自受孕之日开始分别喂食无硒（对照组）、低硒（含硒量0．015mg／kg）、中硒（含硒量0．15mg／kg）、高硒（含硒量1．5mg／kg）饲料,喂至母鼠分娩后21d,给断乳仔鼠继续喂食原饲料。处死44日龄仔鼠,取其上下颌后牙经人工致龋液处理,用增强肉眼光学检查、激光龋齿诊断仪DIAGNOdent、激光共聚焦扫描显微镜（CLSM）检测不同硒水平作用下大鼠牙齿脱矿程度。结果4组大鼠牙齿脱矿程度差异均有统计学意义（均P〈0．05）。增强肉眼光学检查、激光龋齿诊断仪及CLSM等3种不同方法检测均显示随硒增高大鼠牙齿脱矿程度加重,但低硒组脱矿程度明显低于对照组,差异有统计学意义（P〈0．05）。结论发育时期摄入硒能影响牙的龋易感性,高水平硒使大鼠牙齿更易于龋坏,低水平硒可降低龋易感性。     

纳米硒与亚硒酸钠在高碘致小鼠氧化损伤中的干预作用

[目的]研究比较纳米硒和亚硒酸钠对高碘致小鼠部分组织氧化损伤的干预作用。[方法]将48只雄性昆明小鼠被随机分为适碘组[50μg/L碘酸钾(KIO3)]、高碘组(3 000μg/L KIO3)、亚硒酸钠组(3 000μg/L KIO3+0.193 mg/kg硒)、纳米硒组(3 000μg/L KIO3+0.193 mg/kg硒),每组12只。4周后处死小鼠,测定血清、肝脏、肾脏组织的谷胱甘肽过氧化物酶(GSH-Px)活力、以及丙二醛(MDA)水平。观察甲状腺病理变化。[结果]与适碘组相比,高碘组血清、肝脏和肾脏中GSH-Px活力均明显下降,差异有统计学意义(P<0.05);肝脏中MDA含量下降,差异有统计学意义(P<0.05);肝脏和肾脏脏器系数均增加,差异有统计学意义(P<0.05)。与高碘组相比,亚硒酸钠组血清和肝脏中GSH-Px活力均明显升高,差异有统计学意义(P<0.05);肾脏中MDA含量增加,差异有统计学意义(P<0.05);肝脏脏器系数下降,差异有统计学意义(P<0.05);血清和肝脏中MDA含量均下降。纳米硒组血清、肝脏和肾脏中GSH-Px活力均明显增加,差异有统计学意义(P<0.05);血清和肝脏中MDA含量均明显下降,在肾脏中增加,差异有统计学意义(P<0.05);肾脏脏器系数下降,差异有统计学意义(P<0.05)。高碘组甲状腺组织出现弥漫胶质性甲状腺肿。[结论]高碘摄入可致小鼠氧化性损伤,补硒有一定干预作用,纳米硒的干预效果优于亚硒酸钠。     

Selenium Cycling Across Soil-Plant-Atmosphere Interfaces: A Critical Review

Selenium (Se) is an essential element for humans and animals, which occurs ubiquitously in the environment. It is present in trace amounts in both organic and inorganic forms in marine and freshwater systems, soils, biomass and in the atmosphere. Low Se levels in certain terrestrial environments have resulted in Se deficiency in humans, while elevated Se levels in waters and soils can be toxic and result in the death of aquatic wildlife and other animals. Human dietary Se intake is largely governed by Se concentrations in plants, which are controlled by root uptake of Se as a function of soil Se concentrations, speciation and bioavailability. In addition, plants and microorganisms can biomethylate Se, which can result in a loss of Se to the atmosphere. The mobilization of Se across soil-plant-atmosphere interfaces is thus of crucial importance for human Se status. This review gives an overview of current knowledge on Se cycling with a specific focus on soil-plant-atmosphere interfaces. Sources, speciation and mobility of Se in soils and plants will be discussed as well as Se hyperaccumulation by plants, biofortification and biomethylation. Future research on Se cycling in the environment is essential to minimize the adverse health effects associated with unsafe environmental Se levels.     

Biomarkers of Selenium Status

The essential trace element, selenium (Se), has multiple biological activities, which depend on the level of Se intake. Relatively low Se intakes determine the expression of selenoenzymes in which it serves as an essential constituent. Higher intakes have been shown to have anti-tumorigenic potential; and very high Se intakes can produce adverse effects. This hierarchy of biological activities calls for biomarkers informative at different levels of Se exposure. Some Se-biomarkers, such as the selenoproteins and particularly GPX3 and SEPP1, provide information about function directly and are of value in identifying nutritional Se deficiency and tracking responses of deficient individuals to Se-treatment. They are useful under conditions of Se intake within the range of regulated selenoprotein expression, e.g., for humans <55 μg/day and for animals <20 μg/kg diet. Other Se-biomarkers provide information indirectly through inferences based on Se levels of foods, tissues, urine or feces. They can indicate the likelihood of deficiency or adverse effects, but they do not provide direct evidence of either condition. Their value is in providing information about Se status over a wide range of Se intake, particularly from food forms. There is need for additional Se biomarkers particularly for assessing Se status in non-deficient individuals for whom the prospects of cancer risk reduction and adverse effects risk are the primary health considerations. This would include determining whether supranutritional intakes of Se may be required for maximal selenoprotein expression in immune surveillance cells. It would also include developing methods to determine low molecular weight Se-metabolites, i.e., selenoamino acids and methylated Se-metabolites, which to date have not been detectable in biological specimens. Recent analytical advances using tandem liquid chromatography-mass spectrometry suggest prospects for detecting these metabolites.