微量元素硒的生物拮抗作用

<正> 近年来,化学元素拮抗现象不断被发现,使人们对人体内生命元素有了更深刻的认识。所谓拮抗作用就是在自然界中,金属或类金属间的各种相互作用会影响生物活性或毒性,阴离子之间也有类似作用,如铜和钼,酶和铁,铁和锰和铅之间都具有拮抗作用。拮抗作用的机制是:①机体内元素间直接反应,如硒和镉的难解离化合物,导致镉毒性消失,②蛋白质活性基团对不同元素配位能力的差异导致置换反应发生,如硒锌对汞性的抑     

微量元素对铅毒性的影响

膳食中微量元素锌,铁和硒可影响人体对铅毒性的敏感性。铁缺乏可使铅吸收和毒性增强,铅可影响血红素合成途径中铁的代谢。由于缺铁本身可影响儿童智力发育,因此铅暴露和铁缺乏与儿童认知和赤发育损伤可能有一定关系。硒可轻度拮抗铅毒性。锌的营养状况可影响组织中铅蓄积和机体对铅毒性的敏感性,铅 对称站缺乏可能导致血红素合成和药物代谢受阻,影响血中含锌酶的活性;锌在一定程度上还可拮抗铅对细胞的毒性作用。     

锌与三大物质代谢

锌与三大物质代谢赵汉芬（襄樊市卫生学校生化教研室襄樊４４１０２１）锌是为机体正常生长、蛋白质代谢、膜稳定性及２００余种金属酶发挥功能所必需的一种微量元素［１］。在体内分布广泛，参加很多的生理生化功能。锌在机体内的平衡或紊乱，对人类的健康或疾病的发生有...     

锌的生物功能及其与几种常见必需元素的作用关系

锌是生物体内的必需微量元素，参与人体多种酶的合成，在核酸、蛋白质、糖、脂质代谢及RNA、DNA合成中发挥重要作用，对物质代谢起调节作用，具有广泛的生物功能。锌元素缺乏或过多必将引起一系列生化紊乱，并出现相应的病理改变和疾病，高锌能降低人体的免疫功能，影响铜、铁的利用，甚至诱发某些癌症。本文对人体内锌的生物功能及锌和其它常见必需元素间的作用进行了概述。     

微量元素与原发性高血压

微量元素参与机体的各种代谢 ,对于维持人的生命活动发挥着重要的作用。原发性高血压是一种常见的心血管疾病 ,也是冠心病和脑卒中的主要危险因素之一。机体内某些微量元素在原发性高血压的发生发展过程中起到一定的作用 ,人体内的微量元素锌、铜、钴的缺乏均可导致高血压的发生或加剧 ;有机锗可有效地改善高血压症状 ;减少患者体内铅、镉负荷 ,有利于高血压的恢复和症状的改善。近年来应用锌制剂治疗高血压 ,取得了一定的疗效     

健康文摘

现代医学研究表明,锌是人体必需的微量元素,而尘肺患者血中锌元素含量则明显低于正常人。研究者通过多方面的研究探索.发现了锌具有稳定细胞膜、拮抗石英粉尘的细胞毒性等作用。其作用机制可能是:(1)锌可进入细胞内,与细胞内生物大分子的某些功能基因如羟基、巯基等结合,改变细胞膜通透性,或使细胞外锌直接进入细胞内发挥保护作用,从而稳定细胞膜;     

534例儿童全血微量元素检测结果分析

目的:了解参加体检的儿童体内微量元素水平,为更好地做好营养及保健提供指导。方法:随机抽取0~10岁534名儿童的血样,采用原子吸收光谱仪检测铜(Cu)、锌(Zn)、钙(Ca)、锰(Mg)、铁(Fe)和铅(Pb)元素的含量,并做统计分析。结果:缺铁异常率达58.2%,其次为锌(26.0%)、锰(14.2%),而钙基本正常,铜几乎不缺,微量元素异常率除锌元素女(31.4%)高于男(23.0%)外(P<0.05),其他元素差异无统计学意义(P>0.05),不同年龄段6种元素异常无统计学意义;铅元素各年龄段均有一定异常,总体异常率达21.3%。锌和铅元素与多种元素有高度相关关系。结论:儿童铁、锌缺乏率较高,提示应关注儿童营养均衡,补充必需的微量元素;铅增高,应注意儿童的生活环境,多吃排铅食品,必要时进行药物排铅。     

锌的主要生物学作用及生物学意义

在已知１５种必要微量元素中，锌几乎存在于所有类型生物中，在生物体内含量仅次于铁而占第二位。锌在机体内的主要生物学作用有：维持生物膜正常结构及功能；参与核酸及蛋白质代谢，与基因表达有关；参与酶的构成与激活，参与激素的合成与分泌，影响激素与其受体的结合；并且与胸腺素及细胞因子有关。总之，微量元素锌在机体内的重要作用已越来越受到重视。本文综述了锌在机体内的主要生物学作用及生物学意义。     

儿童全血锌、铁、钙含量检测结果分析

锌是人体的必需元素之一,是人体生长发育的一种极其重要的微量元素,在其体内有重要的生理功能和营养作用,特别是对儿童的免疫功能、创伤愈合、智力发育具有不可忽视的作用。当锌元素缺乏时会引起机体的生物学功能障碍。铁是人体必需的微量元素,它既是合成血红蛋白所必需物质,又是细胞代谢不可缺少的物质,     

哈尔滨市学龄前儿童发锌水平测定

<正>微量元素是机体正常代谢和生长发育所需的物质,具有促进人体生长发育,维护中枢神经系统的完整性,参与人体的免疫系统等功能,与人体健康和疾病有密切关系。检测儿童体内微量元素的动态变化,可及时纠正或补充体内有关微量质代谢的重要元素,具有高度活性。锌参与人体的糖、水、盐、核酸、蛋白质     

儿童血铅水平与钙铁锌关系探讨

目的:探讨儿童血铅水平与钙、铁、锌的相互关系。方法:采用原子吸收石墨炉法和火焰法,分别测定我院门诊1056名患儿的血铅和钙、铁、锌水平,并进行相关分析。结果:1056名儿童中,平均血铅水平为59.357μg/L,铅中毒发生率为17.1%,回归和相关分析显示,儿童血铅与血钙、锌水平差异有显著性(P<0.05),呈负相关关系。结论:儿童铅中毒可导致血钙、锌水平下降。     

微量元素锌 铜与血脂代谢关系的研究进展

正常情况下,人体含有一定量的锌、铜微量元素。血液中极少量的锌、铜对血脂代谢的稳定有一定影响,锌、铜微量元素的缺乏或过量都有可能导致血脂代谢紊乱。从膳食中合理摄取锌、铜对血脂代谢有着非常重要的意义。     

兰州市388例学龄前儿童指血铅、钙、镁、锌、铜、铁浓度分析

目的:了解兰州市3～6岁学龄前儿童的血中铅、钙、镁、锌、铜、铁6种矿物元素的水平,为预防儿童矿物元素缺乏和铅中毒、促进儿童健康发育提供参考依据。方法:在兰州市城区随机选择4所幼儿园共388名儿童,采指尖血80μl,测钙、镁、锌、铜、铁、铅浓度。结果:男孩的血铅、铜、铁均高于女孩,差异有统计学意义(P<0.05)。锌缺乏率最高,为38.92%。总的铅中毒率为12.63%,但3岁组最高,达到28.57%。铅中毒儿童的钙、镁水平明显低于正常儿童,差异有统计学意义(P<0.05)。结论:兰州市3～6岁儿童微量元素缺乏以缺锌为主,铅中毒率较高。儿童缺钙易导致铅中毒,反之,血铅水平较高也影响钙的吸收。防止儿童缺钙是预防儿童铅中毒的重要措施之一。     

Effects of harmful trace elements on iron, zinc and copper: their interactions in animals and humans. II. Lead]

Toxic effect of lead is related, among others, to metabolic interactions with essential trace elements i.e. iron, zinc and copper. Lead stimulates urinary excretion of these elements interfering with their reabsorption in kidney as well as inhibits ceruloplasmin activity in plasma, ferrochelatase activity in reticulocytes and copper- and zinc-dependent superoxide dismutase activity in tissues--with all functional consequences for organism. Iron, zinc and copper deficiency results in increased lead toxicity through considerable enhancement of lead absorption from intestinal tract, producing greater degree of anemia as well as decreasing of metalloenzymes activity. Increasing dietary zinc and probably copper suppresses intestinal absorption of lead. The addition of iron, zinc and copper to the diet prevents lead accumulation within the tissues and subsequent toxicity of this element. It seems that increasing intake of food products containing a lot of essential trace elements can diminish risk of lead toxicity for human.     

抗氧化剂对铅毒防治的作用及机制探讨

铅毒是世界范围内的公害,过去主要采用螯合剂治疗铅毒;由于铅离子可以加剧自由基对细胞的损伤,因此,采用抗氧化剂作为防治铅中毒的辅助疗法已成为大家关心的课题。本文主要综述维生素C和维生素E、蛋氨酸、乙酰半胱氨酸、硫辛酸、硒、锌、牛黄酸、茶叶提取物等抗氧化剂在铅中毒防治中的作用以及有关铅引起细胞氧化损伤的机制。     

Tissue Levels of Lead in Experimentally Exposed Zebra Finches (Taeniopygia guttata) with Particular Attention on the Use of Feathers as Biomonitors

We tested experimentally whether zebra finch feathers can be used as a biomonitor for lead pollution, and we examined whether lead exposure influences the accumulation of zinc into feathers. Two groups of eight adult male zebra finches were dosed with, respectively, 0 and 25 ppm lead as lead acetate in their drinking water. After 30 days, lead-treated zebra finches accumulated significantly higher lead concentrations in brain, fat, kidney, liver, muscle, testes, and regrown outer tail feathers than control individuals. Lead levels in regrown outer tail feathers were significantly higher than in original outer tail feathers in the exposed group. The concentration of lead in original (not regrown) fifth tail feathers at the end of the experiment was significantly higher than lead levels in the original outer tail feathers. Our results indicate that lead in regrown feathers originates both from internal deposition and external contamination through the excretion of the uropygial gland during preening. Lead levels in regrown feathers were significantly correlated with levels in liver, kidney, and muscle, suggesting that feathers can be used as a biomonitor for lead. We found that lead had an influence on the metabolism of zinc. Zinc concentrations in the regrown feathers were significantly lower in the lead-treated group although zinc levels in the liver did not differ significantly. Moreover, lead and zinc concentrations in the feathers were significantly negatively correlated. Received: 30 January 2001/Accepted: 1 July 2001     

芜湖市3~6岁儿童血铅含量的研究

目的了解芜湖市市区3~6岁儿童血铅水平,调查血铅水平与临床症状之间的关系,为控制铅中毒提供依据。方法随机抽取577名儿童,采左手无名指末梢血,用电极溶出法进行测定,同时家长和老师填写儿童家庭情况及铅中毒相关调查表。结果577名儿童中,血铅最大值为194.44ug/l,最小值为0.2ug/l,平均值为53.94ug/l±34.96,以铅中毒基点100ug/l为标准,儿童铅中毒患病率为13.34%,男女患病率差异无显著性(P>0.05),各年龄组儿童铅水平差异有显著性(P<0.05),患病率随年龄增长而升高。儿童铅中毒与儿童注意力不集中、攻击性、挑食、情绪不稳等有相关性。结论铅中毒危害儿童健康,损伤儿童智力,引发行为改变。降低铅危害,应从培养儿童良好卫生习惯、改善环境,注意平衡营养。各保健部门应定期组织筛查,及早发现,早期干预。     

Occupational lead poisoning: Can it be eliminated?

The continued occurrence of occupational lead poisoning and overexposure in the United States represents a serious challenge to the occupational health community. We outline a proposed action strategy which integrates case-based surveillance, hazard surveillance, increased requirements for biological monitoring, and targeted educational activities, with a goal of eliminating occupational lead poisoning. The system provides a simple mechanism for monitoring compliance in lead-using employers, in order to identify employers for enforcement action. Lead poisoning should be viewed as an eradicable condition; successfully solving the persistent lead overexposure problem can serve as a model for approaching other occupational diseases.     

Childhood lead poisoning associated with tamarind candy and folk remedies--California, 1999-2000

Lead poisoning affects children adversely worldwide. In the United States, elevated blood lead levels (BLLs) (>10 microg/dL) result primarily from exposure to lead-based paint or from associated lead-contaminated dust and soil; however, other sources of lead exposure, including folk remedies, Mexican terra cotta pottery, and certain imported candies, also have been associated with elevated BLLs in children. This report describes five cases in California of lead poisoning from atypical sources. Health-care providers should be aware of the potential hazards of certain food products, and community members should be educated about potential sources of lead poisoning for children.     

城市铅污染对人体健康的影响及防治措施

随着城市化和工业化进程的加快,城市土壤、空气、饮水和食品中铅污染日趋严重。论述了城市铅污染,包括土壤、空气、饮水和食品中的铅污染特征及对人体毒害的途径和症状,并提出了城市铅污染的防治措施。