硒对不同水体致癌因子诱发健康人微核的拮抗作用

采用微核检测技术，研究了亚硒酸钠对启东肝癌高发区不同类型饮用水诱发健康人外周血淋巴细胞微核的拮抗作用。结果表明：（１）各实验水体对细胞的毒性作用，宅沟水〉泯沟水〉自来水〉双蒸水。微核率随着实验水体剂量的增加而升高；（２）１ｍｇ／Ｌ的亚硒酸钠浓度对泯沟水，自来水诱发的微核效应有是显的抑制和／或拮抗作用，呈现明显的剂量－效应关系，提示肝癌高发区饮用水体中确存在与肝癌发病相关的致畸因子，补硒确有防与治原     

其他微量元素与铅

许多必需微量元素 (如铁、铅、锌、硒、钴等 )对铅毒具有保护作用或拮抗作用 ,锗和锂也有拮抗铅的作用 (CerklewskiFL ,1 977,1 984;BartonJC ,1 978,1 979;FloraSJS ,1 982 ,1 983 ,1 989;TandonSK ,1 992 ;SinghB ,1 994;韩春姬 ,1 998)。Singh还发现 ,长期给铅的大鼠或长期接触铅的工人 ,血中溴、砷、铷含量升高。铅和微量元素相互作用的最典型例子是Zakrgynska -Fontaine关于头发微量元素的研究 ,作用用 3种统计学方法 (递阶升高分类法、最小间隔树法和重心法 )得到的结果表明铅和镍、钴、镉之间有较好的关联 ;铅与镍、钴、镉有…     

铅中毒细胞遗传学效应

对确诊为铅吸收和铅中毒的铅冶炼５９名，进行了外周血淋巴细胞染色体畸变（ＣＡ），姐妹单体互换（ＳＣＥ），微核（ＭＮ）等细胞遗传学指标检测观察，并与血铅、尿铅、ＺＰＰ、ＦＥＰ及尿δ－ＡＬＡ等生化指标进行相关分析，结果表明，铅毒作用能引起细胞染色体畸变率、姐妹染色单体交换率及微核率提高，提示铅能引起ＤＮＡ损伤，但无明显致突变作用。     

铅对神经系统的作用

铅使ALA增多 ,ALA与γ 氨基丁酸 (GABA)化学结构相似 ,因而与GABA产生竞争性抑制作用 ,GABA位于中枢神经的突触前及突触后的线粒体中 ,因GABA的抑制而干扰神经系统功能 ,如意识、行为及神经效应等改变。铅还能对脑内儿茶酚胺代谢发生影响 ,使脑内和尿中高香草酸 (HVA)和香草扁桃酸 (VMA)显著增高 ,最终导致铅毒性脑病和周围神经病。铅毒性脑病在病理上表现为脑水肿、神经细胞弥漫性变性 ,此外尚可见小脑颗粒层细胞坏死、软脑膜小灶性出血。铅毒性周围神经病 ,最早表现为神经传导速度 (NCV)减慢 ,受损神经主要是神经细胞膜的改…     

血铅测定的局限性

血铅测定虽有许多优点 ,例如样品容易获得 ,分析测定简单等 ,但也有一定的局限性 ,因而对分析结果进行解释时必须谨慎从事。其局限之一是血铅与其他铅暴露指标和摄入量之间的关系呈非线性。不仅低水平暴露时血铅比高暴露时灵敏得多 ,而且血浆铅、尿铅、奶铅与血铅之间也呈非线性。不同代谢产物和效应物 ,例如血红素和核苷酸合成与血铅之间也是非线性关系。因此有人认为 ,血铅不是铅暴露或铅毒效应的最好指标 ,从理论上讲 ,其他指标 ,如血清或血浆铅水平可能对评价铅负荷更为合适。血铅测定的局限性     

铅与贫血的关系

铅对血红蛋白合成的障碍：血红蛋白的合成过程受到一系列酶的作用，当机体受到铅毒作用后，这一合成过程中的一些含巯基酶受到抑制，而发生以下变化：     

为什么生活在同一环境中儿童的血铅远高于成人

与成人相比 ,儿童对铅毒性作用更脆弱。年龄越小 ,对铅毒的易感性越高。由于生理原因 ,儿童对铅吸收多、排泄少。吸收的途径有 :(1 )消化道 :成人对铅的吸收率 5 %～ 1 0 % ,儿童则高达 42 %～ 5 3 % ,较成人高出8%～ 1 0 % ;儿童的胃排空较成人快 ,在胃排空状态下铅的吸收会增加 ;儿童的单位体积摄入量多 ,吃食物 (零食 )次数较多 ,因此通过食物摄入铅量增加 ;儿童的除痰能力差 ,部分呼吸道吸入的铅也会由消化道吸收 ;此外 ,一般吸收入体内的铅由大小便排出 ,而儿童的排泄率低 ,成人的排泄率为 99% ,儿童仅 66%。 (2 )呼吸道 :儿童呼吸道铅…     

在儿童生长发育中铅的危害与锌的作用

综述了在儿童生长发育中铅的危害与锌的作用。认为铅中毒和锌缺乏将严重影响儿童的生长发育。铅对儿童是以中枢神经系统损坏为主,中构神经毒性最普遍的表现形式是智力和行为的异常。锌被誉为“生命之花”,在人的机体内具有极其重要的生理和生化功能,缺锌儿童发育迟缓、智力差、免疫力低下、食欲不振等。而且,锌能够减少组织中铅的蓄积和铅毒性作用的影响,补锌能有效降低人体铅的含量。葡萄糖酸是唯一被列入非处方药（OTC）目录的理想的有机锌补充剂。     

硒与艾滋病

对微量元素硒在艾滋病防治中的作用、意义和可行性作了总结性综述,内容分为5个方面：（1）硒与艾滋病发病;（2）硒与艾滋病发展;（3）硒与艾滋病结局;（4）硒与艾滋病诊断;（5）硒与艾滋病防治。     

硒与铅

硒和铅是一对拮抗元素。高秋华发现,喂铅小鼠血和组织中硒浓度显著降低而铅含量显著增加,同时喂硒可使小鼠血、肾、脾中的蓄积铅和MDA显著降低(P<0.01)。阮迪云对发育过程中的大鼠所做的研究也证明,硒可使染铅大鼠肝、脑、血浆和眼球中的铅含量降低到铅处理组的三分之一左右,使肝、脑、血浆的MDA浓度分别下降37％、31％和27％,并可保护铅引起的视觉损伤。高泽宣的研究表明,大鼠醋酸铅[5mg/(kg·d)]染     

Simultaneous determination of selenium and lead in whole blood samples by differential pulse polarography

The polarographic reduction of lead in the presence of selenite gives rise to an additional peak corresponding to the reduction of lead (Pb) on adsorbed selenium (Se) on mercury at −0.33 V. The selenium and lead content can be determined using this peak by the addition of a known amount of one of these ions first and then the second ion. The linear domain range of lead is 5.0×10⁻⁷–2.0×10⁻⁵ M and for selenium 5.0×10⁻⁷–1.0×10⁻⁵ M. Using this method 4.90×10⁻⁷ M Se(IV) and 1.47×10⁻⁶ M Pb(II) in a synthetic sample could be determined with a relative error of +2.0% and 1.8%, respectively (n=4). A recovery test after acid digestion for a synthetic sample was 97% for selenium and 96.5% for lead. The method was applied to 1 ml of digested blood, and 328±23 μg l⁻¹ Se(IV) and 850±62 μg l⁻¹ Pb(II) could be determined with a 90% (n=5) confidence interval.     

Iodine status and the effect of soil erosion on trace elements in Nanka and Oba towns of Anambra State, Nigeria

Iodine Deficiency Disorders (IDD) is common in all populations. Iodine and other trace elements naturally occur in the soil but erosion leaches off these elements from the soil. This results in a continued loss of trace elements from the soil. In the present study, the levels of iodine, selenium, zinc and lead in the environment (measured in soil, bitter leaves (Vernonia amygdalina), cassava roots (mannihot utilissima, staple food in Nigeria), and drinking water) and urinary iodine from school children (n=200), pregnant women (n=60) and women of child bearing age (n=60) were determined for Nanka prone to soil erosion and Oba all in Anambra State, Nigeria (used as control) to assess their risk to IDD. The levels of selenium, zinc and lead were analysed using Atomic Absorption Spectrophotometry while the levels of iodine in the environment and urinary iodine were estimated using the method of Dunn et al.,(1993). In this study there was a positive correlation between iodine and the metals. The results show that the mean concentrations of total soil zinc (0.69 +/- 0.16 ppm); lead (0.40 +/- 0.12 ppm) values in Oba were significantly (p < 0.05) higher than values from Nanka (Zn = 0.33 +/- 0.10 ppm; Pb = 0.21 +/- 0.09 ppm). However, total soil values for selenium and iodine in soil were not significantly different in the two communities. Mean concentration of total vegetable zinc (0.63 +/- 0.14 ppm) value in Oba is significantly (p < 0.05) higher than the value from Nanka (Zn = 0.31 +/- 0.07 ppm). However, total vegetable values for I, Se and Pb were not significantly different in the two communities. Also, mean concentration of total cassava zinc (0.65 = 0.15 ppm) in Oba was significantly (p < 0.05) higher than Zn (0.44 +/- 0.1l ppm) from Nanka. However, values for Se, Pb, and I were not significantly different in the two communities. Mean concentration of total water iodine (105.25 +/- 10.44 microg/L) in Oba was significantly (p < 0.05) higher than the value from Nanka (I = 89.8 +/- 6.42 microg/L). However, total water values for Se, Zn, and Pb were not significantly different in the two communities. The mean urinary iodine concentration of 170.65 +/- 27.17 microg/L in school children from Oba was significantly higher (p < 0.05) than the mean concentration of 156.12 +/- 16.48 microg/L found in school children from Nanka. However, the mean urinary iodine concentration of all the women (pregnant and non-pregnant) were not significantly different in the two communities but they are below the recommended daily intake. The results show that people living in Nanka and Oba, could be at risk of IDD.     

Formation of Metal Selenide and Metal–Selenium Nanoparticles using Distinct Reactivity between Selenium and Noble Metals

Small Se nanoparticles with a diameter of ≈20 nm were generated by the reduction of selenium chloride with NaBH₄ at ?10 °C. The reaction with Ag at 60 °C yielded stable Ag₂Se nanoparticles, which subsequently were transformed into M–Se nanoparticles (M=Cd, Zn, Pb) through cation exchange reactions with corresponding ions. The reaction with Pt formed Pt layers that were evenly coated on the surface of the Se nanoparticles, and the dissolution of the Se cores with hydrazine generated uniform Pt hollow nanoparticles. The reaction with Au generated tiny Au clusters on the Se surface, and eventually formed acorn‐shaped Au–Se nanoparticles through heat treatment. These results indicate that small Se nanoparticles with diameters of ≈20 nm can be used as a versatile platform for the synthesis of metal selenide and metal–selenium hybrid nanoparticles with complex structures.     

Study of the influence of carboxymethylcellulose on the absorption of selenium (and selected metals) in a target plant

The aim of the present paper is the study of the influence of a polysaccharide (carboxymethylcellulose, CMC) on uptake by a target plant Lactuca sativa (LS) of selenium and some metals. LS was grown on a well characterized soil: such as, treated with 1.5 mg kg⁻¹ Se(IV) only and with two levels of CMC (3 and 30 mg kg⁻¹). Similar experiments were carried out by using Se(VI) instead of Se(IV). Uptake was evaluated through the quantification of total content of Se in dried leaves and roots by a suitable technique (graphite furnace atomic absorption spectrophotometry, instrumental neutron activation analysis and differential pulse cathodic stripping voltammetry). Results evidenced as the uptake of selenium was dependent on the form of selenium added to the soil: Se(VI) is accumulated much more then Se(IV) according to its lower toxicity and higher mobility. The simultaneous presence of CMC led to a lower selenium uptake in leaves, whereas no clear influence was evidenced in roots. Furthermore, the presence of CMC influenced also the mobility process (soil→plant) of several other metals: a lower content of them was detected in plants when CMC was present in the soil.     

Analytical methods for the speciation of selenium compounds: a review

Selenium, like sulphur, exists in the environment in several oxidation states and as a variety of inorganic and organic compounds. Dissolved inorganic selenium can be found in natural waters as selenide Se (–II), as colloidal elemental selenium Se (0), as selenite anions HSeO ₃ ^– and SeO ₃ ^2– i.e. Se (+IV) and as the selenate anion (SeO ₄ ^2– ) i.e. Se (+VI). Organic forms of selenium that may be found in organisms, air or in the aqueous environment, are volatile (methylselenides) or non volatile (trimethylselenonium ion, selenoamino acids and their derivatives). Knowledge of the different chemical forms and their environmental and biomedical distribution is important because of the dependence of bioavailability and toxicity on speciation. This paper reviews the different analytical methods used for the speciation of selenium compounds, with special attention to inorganic selenium and organoselenium species.     

Spectrofluorimetric kinetic determination of selenium (IV) by flow injection analysis in cationic micellar medium

A sensitive catalytic kinetic spectrofluorimetric method for determining ng ml(-1) of selenium by flow injection analysis has been developed. The method, based on the catalytic effect of Se (IV) on the reduction of resorufin by sulphide, in the presence of cetylpyridinium chloride, is monitored spectrofluorimetrically (lambda(ex)=480 nm; lambda(em)=583 nm). The linearity range of the calibration graph is dependent on the concentration of sulphide. The variables affecting the rate of the reaction were investigated. The method is simple, rapid, precise, sensitive, and widely applicable. The limit of detection is 1 ng ml(-1) Se (IV), and the calibration range is 5-1000 ng ml(-1). Sampling rate is 60 samples h(-1), and the relative standard deviation of 12 determinations of 100 ng ml(-1) Se was 0.76%. The determination of Se (IV) in the presence of Se (VI) and total selenium is described. The method was applied to the determination of Se in selenium tablets, and several synthetic samples.     

Variability in the distribution of selenium in healthy heart tissue measured by neutron activation analysis

Chronic dietary deficiency of selenium has been shown to be associated with degenerative heart disease in production animals in the U.S. and in the human in parts of China. In the latter, subjects in the endemic areas suffer high rates of a cardiomyopathy known as Keshan's Disease which is normally fatal in early adulthood and can be prevented, or reversed in its early stages, via selenium supplementation. Selenium, as the active moiety in the enzyme glutathione peroxidase, protects against oxidative attack of cell membranes by peroxides formed during normal metabolism. In this study, we investigated the distribution of selenium in healthy porcine and bovine heart tissue freshly collected at slaughter. The whole heart was perfused with DI water and carefully de-fatted. Representative samples of left and right atria and ventricles and the interventricular septum were collected, lyophilized and homogenized prior to preparing replicate samples for analysis. Replicates were analyzed for selenium via an INAA scheme employing a 5, 15 and 25 second irradiation (φ_th = 8·10¹³ n·cm⁻²·s⁻¹), decay and real-time count (^77mSe,T _1/2=17.4 s), respectively, using high-resolution gamma-ray spectroscopy with Westphal pulse pile-up correction. Selenium distribution will be discussed relative to differentiated function and oxygenation of the specific tissues.     

Kinetic-spectrophotometric determination of selenium in natural water after preconcentration of elemental selenium on activated carbon

A simple, accurate, sensitive and selective method is described for rapid determination of ultra-trace quantities of selenium. Selenium (IV) was collected on activated carbon after reduction to elemental Se by l-ascorbic acid. The collected selenium was then determined based on its accelerating effect on the oxidation reaction of methyl orange with bromate in acidic media. Total amount of Se(IV) and Se(VI) were collected on AC after their reduction by hydrazine. Se(IV), Se(VI) and total selenium could be determined by the method. Selenium in the range 10-10 000 ng could be determined by the method. The method was used to the determination of Se(IV), Se(VI) and total selenium in natural water with satisfactory results.     

Selenium concentrations of selected medicinal and aromatic plants in Turkey

Recent scientific studies have proven the importance of trace elements on human health. The main food supplies are plants and animals, which are significant sources of these minerals. Studies on determining mineral compositions of herbs, spices and some other crops have increased all over the world. Published works revealed that spices, herbs and medicinal plants should be consumed to obtain beneficial trace elements. Selenium (Se), one of the most vital trace elements, has a significant role in human diet acting as a preventative agent against some serious illnesses. Despite numerous scientific works on mineral compositions of medicinal and aromatic plants, investigations of selenium content in these foods could not be successfully studied until recently due to the lack of suitable analytical methods for selenium analysis. Thus, publications on selenium concentrations of foods are recent. In this regard, selenium contents of some medicinal and aromatic plants commonly used as spices, herbal teas and traditional medicines in Turkey were studied in the present research. Selenium contents of the most used parts of these plants were analyzed by ICP-OES (Varian Vista-Pro, Australia). Of the analyzed 26 medicinal and aromatic plants, the highest Se concentration (1133 microg kg-1) was found in sweet basil (Ocimum basilicum L.) and the lowest in sumac (Rhus coriaria L.) fruits (11 microg kg(-1)).     

Selenite and Selenate Speciation in Natural Waters: Interaction with Divalent Metal Ions

Selenium is a trace element of environmental relevance. Studies on its solution chemistry are scarce and were mostly carried out under experimental conditions of little relevance to environmental research. Thus, we have performed new studies of selenium speciation in solutions of low ionic strength, in contrast to those prevailing in the literature data. In this work, potentiometric titrations (at 20.0 °C, and I=0.15 mol⋅L⁻¹ NaClO₄) were carried out for systems containing Se(VI) or Se(IV) oxyanions and divalent metal ions (Mg, Ca, Sr, Ba, Mn, Fe, Co, Ni, Cu, Zn, Cd, Hg, and Pb). Ion pairs such as [M(SeO₄)] and [M(HSeO₄)₂], or [M(HSeO₃)]⁺ and [M(SeO₃)], exist in solutions. The data reported here provide the basis for determining selenium speciation in natural aquatic systems, on which the bioavailability and toxicity of this element depends.