微量元素硒的研究进展

硒是动物机体必需微量元素之一,在机体内发挥着十分重要的生物学功能。研究发现,有机硒相对于无机硒毒性小、生物利用率高、生物活性强。就硒、有机硒的研究近况展开综述。     

硒对镉引起的大鼠肝脏超氧阴离子和羟自由基生成的影响

目的研究体外和体内染毒条件下Na2SeO3对CdCl2诱导的大鼠肝组织超氧阴离子(.O2-)和羟自由基(.OH)生成的影响。方法实验动物选用雄性Wistar大鼠。体外实验时,制备肝匀浆,用2.185、8.750和35.000μmol/L的Na2SeO3分别与2.185、8.750和35.000μmol/L的CdCl2联合作用。体内实验时,用3 mg/kg Na2SeO3和1mg/kg CdCl2联合作用,腹腔注射染毒。采用分光光度比色法、荧光法和电子自旋共振测定.O2-和.OH。结果在体外染毒时,2.185和8.750μmol/L的Na2SeO3分别对2.185、8.750和35.000μmol/L的CdCl2诱导的.O2-和.OH的生成具有良好的拮抗作用,35.000μmol/L的Na2SeO3与2.185、8.750和35.000μmol/L的CdCl2联合作用在脂质过氧化、.O2-和.OH的生成方面,没有显示拮抗作用。在体内染毒时,3 mg/kg Na2SeO3和1 mg/kg CdCl2在.O2-和.OH的生成上存在拮抗作用。结论在适宜的剂量条件下,Na2SeO3对CdCl2诱导.O2-和.OH的生成具有一定的拮抗作用。     

高碘对仔鼠甲状腺功能影响及硒干预作用

目的 研究高碘摄入对小鼠仔代甲状腺的影响及硒的干预作用。方法 将60只Balb／c小鼠随机分为4组：正常对照组、高碘组（I 3000μg／L）、单独补硒组（Se200μg／L）、高碘（I3000μg／L）＋Se（200μg／L）组。各组分别饮用自来水、高碘水、加硒水和高碘加硒水，饲以纯系鼠饲科。4个月后，测尿碘，雌雄交配。观察14d龄仔鼠甲状腺病理变化，测定14d龄和28d龄仔鼠血清促甲状腺激素（TSH）、总T4（T4）、总T3（TT3）和rT3水平。结果高碘组14d龄仔鼠出现弥漫胶质性甲状腺肿，高碘补硒组甲状腺肿减轻；14d龄仔鼠高碘组因清TT4水平显著低于对照组和高碘加硒组（P〈0．05），而TT3有降低的趋势，高碘组TSH显著高于对照组和高碘加硒组（P〈0．05）；28d龄仔鼠血清TT4和TT3水平以及TSH水平组间差异无统计学意义。结论高碘引起仔鼠甲状腺形态和功能异常改变，补硒具有一定改善作用。     

硒和/或维生素E对实验性高脂血症大鼠心、肝、肾及血清脂质过氧化和一氧化氮含量的影响

目的 :观察硒和 或维生素E对高脂饲料所致实验性高脂血症大鼠心、肝、肾及血清脂质过氧化和一氧化氮含量的影响 ,探讨硒和维生素E抗脂质过氧化的作用。方法 :采用高脂饲料致大鼠实验性高脂血症 ,然后分组给予经预试后的硒和 或维生素E ,4wk后行乙醚麻醉取血 ,同时取心、肝、肾组织作匀浆 ,采用硫代巴比妥 (TBA)法测各组织或血清丙二醛 (MDA)含量以反映脂质过氧化水平 ;采用硝酸还原酶法测定上述组织的一氧化氮 (NO)含量。结果 :高脂饲料可致实验性大鼠高脂血症 ,与对照组比较 ,甘油三脂 (TG)、极低密度脂蛋白胆固醇 (VLDL C)升高 (P <0 .0 5) ;总胆固醇 (T CHOL)、低密度脂蛋白胆固醇 (LDL C)升高 (P <0 .0 1 )。高脂饲料可致部分组织或血清的脂质过氧化作用加强 ,增加各实验组织MDA含量 ,其中肝脏和血清MDA较对照组高(P <0 .0 5)。高脂饲料可致心肌及肝脏组织NO含量降低但却升高血清及肾脏组织NO含量。单独使用硒或维生素E或二者合用可不同程度降低高脂饲料所致的MDA含量升高 (P <0 .0 5或P <0 .0 1 ) ,也能不同程度地增加心、肝、肾及血清的NO含量 (P <0 .0 5或P <0 .0 1 ) ,合用比单独使用作用更明显。结论 :硒和维生素E单独或联合应用可降低高脂血症大鼠血脂升高所致的脂质过氧化增强作用 ,并能增加     

富硒鸡蛋中十七种元素含量分析

<正>硒作为人体必需微量元素之一,对人类健康的巨大作用是其他物质无法替代的。临床医学证明,威胁人类健康和生命的四十多种疾病都与人体缺硒有关,如癌症、心血管病、肝病[1]、白内障、胰脏疾病、糖尿病、内分泌代谢病、老年性便秘、生殖系统疾病等[2-4]。无论是动物实验还是临床实践,都说明了应该不断从饮食中得到足够     

Vitamin B12 malabsorption and omeprazole therapy.

The media is the most popular vehicle through which consumers receive nutrition information, and is powerful in influencing food selection and health behaviors. Unfortunately, media messages surrounding nutrition are often inconsistent, confusing, and do not enable the public to make positive changes in health behaviors. The process to improve this scenario begins with communication between scientists and journalists. Scientists can take several steps to insure the results of their research are reported to the public accurately and, thereby, contribute to the achievement of the nation's public health goals.     

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.     

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.