微量元素硒代谢及硒蛋白基因表达调控最新研究进展

概述了食物或饲粮中硒的形式 ,组织硒分布模式 ,硒代谢途径 ,硒营养状态参数 ,硒蛋白与基因表达调控。为微量元素硒的研究和应用提供参考。     

说说补益类中药中的“硒”

很多补益类中药中都含有硒。硒是一种微量元素。1817年被发现,直到20世纪70年代,科学家才认识到硒是人和动物必需的微量元素,有着神奇而独特的生理功能。抗氧化作用自由基被称为"百病之源"。过多的自由基和过氧化脂质会损害机体代谢和危及组织器官。硒是谷胱甘肽过氧化物酶的重要组成成分,对自由基和过氧化脂质的清除起着非常重要的作用。研究证实,硒与锌、铜     

硒的致癌与抗癌

硒作为动物和人体营养必需的一种微量元素已受到普遍重视。越来越多的国家和地区用不同方式补充硒,大面积防治家畜和家禽的硒缺乏病取得成功。补充硒已成为畜牧、兽医工作中一个不可缺少的手段。关于硒与人体健康和疾病的关系的报告也日益增多,已开始将硒试用于某些疾病的防治。然而,长期以来硒具有致癌作用的说法,又给在动物和人体的疾病防治中使用硒造成很大顾虑。不少国家因此迟迟未在卫生法规中准许在家畜或家禽饲料     

植物、硒与人类健康

硒元素对动物、微生物及其它一些真核生物来说是一种必需营养素。尽管还未证实硒是维管植物必需的微量元素,但一些植物能够蓄积硒并将其转化为具有生物活性的物质,这对人类营养和健康以及环境都具有非常重要的意义。具有蓄积硒作用的植物不但为研究硒代谢提供了独特的研究材料,而且也提供了一个研究如何改变植物的硒代谢、植物对硒的耐受性,以培育含有较高抗癌硒化合物的食用作物及适合在硒污染的土壤生长的植物的遗传资源。     

粮食硒与大骨节病和克山病的研究

<正> 硒于1817年由端典科学家Bertelous发现,直至1957年美国Schwarz证明硒是动物营养的一种必需微量元素以来,世界上对硒的生物医学研究正处于方兴未艾之势。我国学者对硒缺乏与大骨节病,克山病关系的研究已引起各国学者的瞩目。     

硒在地方病中的部分生化作用

随着对硒研究的深入 ,现在已证实硒是人体必需的微量元素 [1 ,2 ]。硒缺乏可导致或加重多种疾病。就地方病而言 ,硒与克山病的关系使得硒被确认为人体必需的微量元素 ,目前随着对自由基在体内代谢研究的深入 ,硒与其它几种地方病的关系也越来越明确。1　硒与克山病克山病是一种原因不明的地方性心肌病。二十世纪七十年代 ,我国克山病研究者发现克山病病区都处于低硒地带 [3] ,病区人群内外环境样品硒含量明显低于非病区对照组。而克山病病人和病区人群存在以低硒为中心的代谢改变 [4] :如血液中 GSH- Px活力降低 ,体内自由基含量升高。而…     

说东道“硒”

硒是目前被世界公认的人体必需微量元素之一．人体的诸多代谢活动、免疫防御、解毒功能都缺不了它。硒是一位瑞典化学家在1817年最早发现的．但直到1934年才引起人们的注意。此后,随着科学家对硒开展的广泛、深入的研究．人们逐渐证实,硒不仅是动物必需的营养素,也是人体所必需的一种微量元素。上世纪70年代,我国开展了克山病的防治研究．进一步证实．硒是人体必需的微量元素,并提出了人体硒的需要量。     

科学补硒:延缓衰老的“法宝”

硒是人体内重要的必需微量元素之一。研究发现．硒在细胞抗氧化系统中占有重要位置,具有保护细胞膜结构、维持生物功能、增强机体免疫力、抗衰老及预防疾病等重要作用。1973年,世界卫生组织（WHO）将硒确定为人和动物生命活动的必需微量元素;1988年,我国营养学会也将硒列为15种每日膳食营养素之一。目前,硒的营养作用越来越引起社会各界的广泛重视。     

不同有机硒源对鹌鹑肉、蛋中硒含量及血清生化指标的影响

<正>硒(selenium)是动物必需的微量元素,它参与动物生命维持、生长、繁殖、免疫等生理代谢。人们日常饮食中的硒含量低于人体的正常需要,研究表明,如果提高动物产品的硒含量,不仅可改善动物的健康状况,还能提高动物产品(肉、乳和蛋品等)的价值[1]。但当前饲料中普遍使用的硒源亚硒酸钠存在吸收率低、过氧化作用     

硒

<正>膳食硒摄入缺乏和过剩对人类健康影响一直是人们关注的焦点。国外对硒的认识源于动物硒中毒和缺乏。1973年发现硒是谷胱甘肽过氧化物酶(glutathione peroxidase,GPX)的必需组分,第一次揭示了硒具有生物活性。我国对硒的最初认识是上世纪六十年代湖北恩施地区的人体硒中毒。七十年代补硒有效控制克山病暴发流行使我们认识到硒对人体健康的重要性。这也为确认硒是人体必需微量元素奠定了基础。八十年代,硒在预防疾病和人体营养中作用的报告不断涌现。     

Selenium in human environment

Selenium belongs to the group of elements which may be regarded as useful only in a very narrow range, while in excess doses they exert a harmful action. The content of the element in soil is usually from 0.1 to 2 mg/kg, with the Scandinavian soils have a low level of selenium, not exceeding 0.3 mg/kg. The highest level, exceeding 3000 mg/kg was noted in Northern Ireland. Selenium content in soil over 500 mg/kg produces chronic selenium intoxication in domestic animals. Selenium accumulation by plants is a selective process and depends on the chemical state of the element in soil and pH of soil. It is considered that the daily requirement for selenium is 50-300 mcg for adults, while the toxic dose is regarded as 5 mg daily. The toxic effects of selenium in the environment include inflammatory processes of the extremities in herbivorous animals (the so called Degnal disease in India and the Alkali disease in Great Britain). Selenium deficiency in the environment leads to the so called white muscle disease in these animals in Great Britain. Selenium is considered also to protect the organism in case of poisoning with lead, mercury or cadmium.     

Effects of a low selenium status on the distribution and retention of selenium in the rat

In the tissues of rats fed a selenium-deficient diet the changes in the selenium content and the retention of the element after administration of a small amount of selenium to the depleted animals were determined. In the liver and in the erythrocytes, which are the main glutathione peroxidase pools, the decrease in the selenium content was great and the retention in the depleted rats only slightly increased in comparison with the control animals fed sufficient amounts of the element. In the testes and in the adrenals the decreases in the selenium content were the smallest, and here retention was about 15 times greater than in the control animals. Also in other tissues, such as the thymus, spleen, bone and kidney, retention was considerably increased in the depleted rats. The results indicate that regulation mechanisms exist, which in nutritional selenium deficiency cause reduced excretion of the element and priority of supply to certain tissues. This, in turn, leads to a redistribution of selenium in the organism and, as the glutathione peroxidase decreases to a greater extent than the selenium, also to a redistribution of the element among its different binding forms. As the selenium content is most probably kept up in particular in sites in which the element is most needed, the findings suggest important functions of selenium in these tissues.     

硒缺乏动物模型的建立及应用

硒是人类和动物维持生命所必需的基本营养元素之一，它在机体内发挥着众多的生物学作用。但是全球缺硒现象非常普遍，硒缺乏成为全球性的普遍问题。为了研究硒缺乏究竟会对人体有何影响，建立缺硒动物模型成为必不可少的关键环节。本文对半个世纪以来国内外低硒动物模型建立的方法以及利用低硒动物模型对硒功能的研究进展作一综述。     

硫氧还蛋白还原酶研究进展

硒蛋白是人和动物必需微量元素硒的主要功能表现形式,硫氧还蛋白还原酶(TrxR)是比较重要的硒蛋白之一,本文对硫氧还蛋白还原酶的分子生物学特点、生物功能、其与某些人类疾病发病机制的关系以及其抑制剂的研究进展进行综述,以期为缺硒性地方病的研究开拓新的思路.     

Selenium content and glutathione peroxidase activity in the testis of the maturing rat

In rats fed a diet with 0.25 mg Se/kg the testis selenium content rose during maturation. The value in 4-mo-old animals (7.0 mg Se/kg dry mass; 0.9 mg Se/kg wet mass) was six times higher than that in 20-d-old weanling rats. By comparison, the selenium content in the main selenium pools, muscle and liver, remained unchanged and rose by half, respectively. Due to the increased selenium requirement of the testis during its pubertal maturation the amount of selenium taken up by the male gonads was 50% of the amount deposited in muscle and liver, whereas before and after that period it was about 10%. Feeding animals a low vitamin E diet had no effect on the rise in testis selenium. Glutathione peroxidase activity was twice as high in 4-mo-old animals as in weanling rats. Because only a small percentage of the element in the male gonads was bound to the enzyme, the rise in testis selenium must have been due to other selenium compounds. The selenium content of the spermatozoa was about 21 mg Se/kg dry mass, which by far exceeded the level of this element in other compartments of the rat. The increase in testis selenium content coincided with the beginning of spermatogenesis, and it may therefore ensure the supply of adequate amounts of the element for the spermatozoa.     

An original discovery: selenium deficiency and Keshan disease (an endemic heart disease)

This is a review article telling a 50-years old story about the studies on selenium deficiency and Keshan disease in China, an endemic heart disease with high case-fatality, as an example of translational research. Extensive cross-sectional epidemiological studies showed that low selenium concentrations in cereal grains and low selenium status of local residents were associated with the occurrence of Keshan disease. Several large population based intervention trials using oral administration of sodium selenite tablets showed significant reduction of Keshan disease incidence. Based on the above evidence, it was concluded that selenium deficiency is the major cause of Keshan disease, although other etiological factors could not be ruled out. The implications of the findings include: provided critical scientific evidence for selenium being an essential trace element for humans; as scientific basis for identifying minimum requirement and RDA/RNI for selenium; and as solid reference for the formulation of effective preventive measures for Keshan disease in China.     

Selenium intake,mood and other aspects of psychological functioning

Selenium is an essential trace element although the level of selenium in food items reflects the soil in which they were grown and thus varies markedly between different parts of the world. The metabolism of selenium by the brain differs from other organs in that at times of deficiency the brain retains selenium to a greater extent. The preferential retention of selenium in the brain suggests that it plays important functions. To date mood is the clearest example of an aspect of psychological functioning that is modified by selenium intake. Five studies have reported that a low selenium intake was associated with poorer mood. The underlying mechanism is unclear although a response to supplementation was found with doses greater than those needed to produce maximal activity of the selenoprotein glutathione peroxidase. Although the functions of many selenoproteins are unknown some play important roles in anti-oxidant mechanisms. As there are suggestions that oxidative injury plays a role in normal aging, schizophrenia, Parkinson's and Alzheimer's disease, the possible role of selenium is considered. Although there is evidence that supplementation with anti-oxidant vitamins shown some promise with Alzheimer's patients, and in preventing the development of tardive dyskinesia in schizophrenics taking neuroleptics, a role for selenium has been little considered.     

Kinetic modeling of selenium metabolism in nonpregnant ewes

The kinetics of selenium metabolism in three nonpregnant ewes were studied by the intravenous injection of 75Se-sodium selenite and measurement of radioactivity responses in blood, tissues and excreta. Stable selenium measurements were also made to determine selenium intake, excretion in feces and urine, and mass of selenium in tissues. Immediately following tracer injection, there was a rapid disappearance of radioactivity from plasma reflecting the uptake of the element by the liver and blood cells. The decrease in plasma radioactivity ceased abruptly by 30-45 min, and was followed by an increase to a peak by 3-4 h and a more gradual biphasic decline thereafter. A kinetic model of selenium metabolism in the whole animal was constructed employing the SAAM/CONSAM computer program. The multiphasic response of plasma radioactivity during a physiological steady state was explained on the basis of rapid hepatic uptake of selenium and its subsequent reappearance in the circulation in protein-bound form followed by further metabolism and excretion of the element. The model provides reference parameter values for 75Se-sodium selenite kinetics in selenium-replete, mature nonpregnant ewes for comparison with the kinetics in animals whose selenium status may be altered.     

硒摄入量对柯萨奇病毒引起的小白鼠实验性心肌坏死的影响

<正> 硒是一种必需的微量元素。自从Schwarz等证明硒是一种抗致坏死因子以来,陆续发现多种动物的多个系统的病征对补硒有良好的反应,其中包括牛、羊、蹊鼠及貂类等动物的心肌坏死。 克山病是一种以心肌坏死为特征的地方病。调查发现所有病区都处于硒贫乏状态,给     

Selenium Intake,Mood and Other Aspects of Psychological Functioning

Abstract

Selenium is an essential trace element although the level of selenium in food items reflects the soil in which they were grown and thus varies markedly between different parts of the world. The metabolism of selenium by the brain differs from other organs in that at times of deficiency the brain retains selenium to a greater extent. The preferential retention of selenium in the brain suggests that it plays important functions. To date mood is the clearest example of an aspect of psychological functioning that is modified by selenium intake. Five studies have reported that a low selenium intake was associated with poorer mood. The underlying mechanism is unclear although a response to supplementation was found with doses greater than those needed to produce maximal activity of the selenoprotein glutathione peroxidase. Although the functions of many selenoproteins are unknown some play important roles in anti-oxidant mechanisms. As there are suggestions that oxidative injury plays a role in normal aging, schizophrenia, Parkinson's and Alzheimer's disease, the possible role of selenium is considered. Although there is evidence that supplementation with anti-oxidant vitamins shown some promise with Alzheimer's patients, and in preventing the development of tardive dyskinesia in schizophrenics taking neuroleptics, a role for selenium has been little considered.