低硒对大鼠血管一氧化氮合酶和微循环的影响

采用低硒饲料饲养大鼠造成体内贫硒。１４周时测定血浆中脂质过氧化物（ＬＰＯ）、前列环素（ＰＧＩ２）和血栓素（ＴＸＡ２）的水平以及部分血液流变学指标。实验第３９周,测定血管组织一氧化氮合酶（ＮＯＳ）活性及一氧化氮（ＮＯ）水平。结果显示,低硒饲料组的血管ＮＯＳ活性、ＮＯ水平显著低于常规饲料的对照组;而在实验第１４周时,当低硒饲料组的血硒、血谷胱甘肽过氧化物酶（ＧＳＨ－Ｐｘ）活性显著下降、血浆ＬＰＯ水平明显上升的同时,其对应的血浆６－酮－ＰＧＦ１α水平也显著降低,但其ＴＸＢ２与对照组无显著差异。此外,随着大鼠体内的贫硒,其红细胞变形能力下降,但红细胞聚集指数和血沉方程Ｋ值提高。因此,硒不足可能会通过影响ＮＯＳ活性和ＰＧＩ２的合成以及红细胞特性而损害微循环功能。     

富硒米对大鼠细胞免疫功能影响的实验研究

为探讨富硒米的剂量对大鼠免疫功能的影响和富硒米用于保健食疗提供有意义的实验依据,选用纯种ＳＤ大鼠４０只,随机分为高中低三个剂量组,分别给予富硒米和常规饲料喂养３０ｄ,称重,取血做Ｔ淋巴细胞转化和自然杀伤细胞活性试验。结果表明：①富硒米能显著提高大鼠Ｔ淋巴细胞转化率,中剂量组与对照组比较有显著性差异（ｔ检验,Ｐ〈０．０５）。②富硒米大鼠ＮＫ活性对照比较,没有显著性差异 。结论是富硒米能显著提高大鼠Ｔ     

硒保护离体培养人肝细胞膜流动性的机制探讨

原代培养人胚细胞经不同剂量硒预保护后，用四氯化碳（ＣＣｌ４）攻击，观察细胞膜流动性及培养液中谷胱甘肽过氧化物酶（Ｓｅ－ＧＳＨ－Ｐｘ）与两二醛（ＭＤＡ）比值的变化．结果；与正常对照组比较，ＣＣｌ４损伤组肝细胞膜流动性明显降低，差异有显著性意义（Ｐ＜０．００１）。与ＣＣｌ４．损伤组比较，硒保护组股流动性显著增大．同时，Ｓｅ－ＧＳＨ－Ｐｘ活性明显提高，ＭＤＡ产生量显著减少，差异均有显著性意义（Ｐ＜０．０１）。且细胞膜流动性与Ｓｅ－ＧＳＨ－Ｐｘ／ＭＤＡ比值呈显著正相关（ｒ＝＋０．９４７３，Ｐ＜０．０１）。因此，本文认为硒可以提高Ｓｅ－ＧＳＨ－Ｐｘ／ＭＤＡ比值，增强细胞抗氧化能力，维护人肝细胞膜流动性．     

河南省地方甲病,克山病,大骨节病病区不同人群发硒含量及全…

测定了河南省地甲病，克山病，大骨病病区不同人群发硒含量及ＧＳＨ－Ｐｘ活性，并作了对比分析，结果表明，对照组人群发硒含量及ＧＳＨ－Ｐｘ活力显著高于地甲病，克山病及大骨节病区，病区之间无显著性差异。     

碘缺乏病病区胎儿及孕妇硒含量和硒—谷胱甘肽过氧化物酶活性研究

测定了麻江县和贵出市郊两地胎儿组织，胎儿和孕妇血硒含量和谷胱甘肽过氧化物酶活性，同时测定了生态环境中硒含量，结果发现，麻江地区环境硒含量低，孕妇血硒水平和红细胞ＧＰｘ活性明显低于贵阳地区，胎儿组织及血Ｓｅ含量和ＧＰｘ活性也有一致性低于贵阳地区的趋势显示麻江人群因摄硒不足而存在的硒代谢紊乱。调查的两地区均连续碘盐防治十年以上，但麻江地区人群仍处在高促甲状腺激素水平，学龄儿童甲肿率还显著高于贵阳，这些     

富硒肝对大鼠GSH-Px、GSH和游离巯基含量的影响

为观察富硒肝和亚硒酸钠对大鼠抗氧化能力的影响。将6只大鼠分为两组:A组用亚硒酸钠[按Se元素计,6μg/(只.d)]灌胃,B组用富硒肝[按Se元素计,6μg/(只.d)]灌胃。于灌胃第0、4、8、12、16、20天内眦采血,测定血浆和血细胞内液中GSH-Px活力以及GSH、游离巯基的含量。结果表明:①给药20 d后A、B组血浆和血细胞内液GSH-Px活力和GSH含量均明显高于灌胃前(P0.05);②A、B组血浆中游离巯基的含量略有增加,而血细胞内含量则大幅降低(P0.05)。结论:经口给予富硒肝可诱导大鼠产生较多的抗氧化物质,增强大鼠的抗氧化能力。其作用可达同剂量亚硒酸钠水平。     

食用富硒谷物成人血硒含量测试

为防治克山病、大骨节病，采用提高食用谷物含硒量的方法，达到人日摄硒量的要求。经中国农科院检测该富硒谷物的含硒量为１２０×１０－９～４５０×１０－９，其中有机硒含量达９９％，被试验人群食用富硒谷物一周后，其血硒浓度平均为１５６．６８ｎｇ／ｍＬ，同对照组比较变化显著（Ｐ＜０．０１），并无年龄、性别的差别．实验期间食用富硒谷物无不良反映。     

血硒与肺癌

硒是谷胱甘肽过氧化物酶（ＧＳＨ－ＰＸ）的组成成分，是人体生命活动所必需的微量元素，本文主要就血硒的流行病学研究、人体硒状况的估价、硒的抗癌机制以及血硒在肺癌诊断和防治中的意义等方面作一概述。     

硒半胱氨酸和硒胱氨酸的间接气相色谱测定──溴化氰－气相色谱法

将硒半胱氨酸（ＳｅＣｙｓＨ）甲基化，对硒胱氨酸（ＳｅＣｙｓ）需还原后再甲基化。它们生成的甲基硒半胱氨酸（ＣＨ＿３ＳｅＣｙｓＨ）能与溴化氰（ＣＮＢｒ）发生专一性反应，定量生成的硒氰酸甲酯（ＣＨ＿３ＳｅＮ）可用气相色谱法（ＧＣ）测定。此法简称ＣＮＢｒ－ＧＣ法，检测限４×１０￣（－８）克ＳｅＣｙｓ，准确度８９．５％，相对标准差１２．１％，非含硒氨基酸不干扰。此法适于样品中微量硒氨基酸（硒蛋氨酸ＳｅＭｅｔ，ＳｅＣｙｓＨ和Ｓｅｃｙｓ）的测定。     

硒半胱氨酸和硒胱氨酸的间接气相色谱测定──溴化氰－气相色谱法

 将硒半胱氨酸（ＳｅＣｙｓＨ）甲基化，对硒胱氨酸（ＳｅＣｙｓ）需还原后再甲基化。它们生成的甲基硒半胱氨酸（ＣＨ＿３ＳｅＣｙｓＨ）能与溴化氰（ＣＮＢｒ）发生专一性反应，定量生成的硒氰酸甲酯（ＣＨ＿３ＳｅＮ）可用气相色谱法（ＧＣ）测定。此法简称ＣＮＢｒ－ＧＣ法，检测限４×１０￣（－８）克ＳｅＣｙｓ，准确度８９．５％，相对标准差１２．１％，非含硒氨基酸不干扰。此法适于样品中微量硒氨基酸（硒蛋氨酸ＳｅＭｅｔ，ＳｅＣｙｓＨ和Ｓｅｃｙｓ）的测定。     

克山病病区硒水平监测的10年总结

对陕西省黄陵县克山病病工欠群内外环境硒水平进行了１０年动态监测。结果表明：①当地产小麦、大米、玉米和黄豆硒含量监测是无明显变化,均仍低于非病区同种粮食硒水平,病区居民所食外地麦面硒含量明显高于当地产小麦硒含量;②病区儿童发硒含量明显上升并已达到非病区水平;③病区人群内环境硒水平提高。可能与食用外地表现和硒磺盐有关。     

Liquid chromatography-electrospray ionization tandem mass spectrometry for on-line characterization, monitoring and isotopic profiling of the main selenium-metabolite in human urine after consumption of Se-rich and Se-enriched food

The metabolism of selenium (Se) in the human body has yet not completely been unravelled and hence, an efficient method for characterization and on-line monitoring of the main Se-compound in human urine after consumption of Se-rich food was developed. Total Se-concentration in human urine after consumption of several Se-rich products was measured with inductively coupled plasma mass spectrometry (ICP-MS). The highest Se concentration in urine was observed after 4-10 h. The urine samples were brought onto a reversed phase column and the Se was detected by ICP-MS. Parameters for liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS-MS) measurements were optimized by using commercially available sugars, because it is known that some of the urinary metabolites contain a sugar moiety. In order to characterize the predominant Se-metabolite, it was necessary to extensively clean-up the sample and preconcentrate the species. The main metabolite was measured on its precursor ion on three different m/z according to three isotopes of Se. Relative peak surfaces matched the relative abundances of the isotopes. The product ions could be measured in a human urine sample in accordance to the product ions of the commercially available sugars. Moreover, the evidence of a selenosugar was demonstrated by the use of the Se-isotopes when measuring the product ions. LC-ESI-MS-MS was proven to be very efficient for the characterization of the main urinary Se-metabolite and can be used for on-line monitoring of the compound in urine samples. The method can be extended for clinical screening after consumption of Se-(en)rich(ed) food by use of the Se-isotopic profile and/or of the typical product ions of (methyl)-N-acetyl-hexosamines.     

河南省地甲病、克山病、大骨节病病区不同人群发硒含量及全血GSH-Px活性的对比分析

测定了河南省地甲病、克山病、大骨病病区不同人群发硒含量及GSH－Px活性，并作了对比分析，结果表明，对照组人群发硒含量及GSH－Px活力显著高于地甲病、克山病及大骨节病区，病区之间无显著性差异。     

Heavy doping and band engineering by potassium to improve the thermoelectric figure of merit in p-type PbTe, PbSe, and PbTe(1-y)Se(y)

We present detailed studies of potassium doping in PbTe(1-y)Se(y) (y = 0, 0.15, 0.25, 0.75, 0.85, 0.95, and 1). It was found that Se increases the doping concentration of K in PbTe as a result of the balance of electronegativity and also lowers the lattice thermal conductivity because of the increased number of point defects. Tuning the composition and carrier concentration to increase the density of states around the Fermi level results in higher Seebeck coefficients for the two valence bands of PbTe(1-y)Se(y). Peak thermoelectric figure of merit (ZT) values of ~1.6 and ~1.7 were obtained for Te-rich K(0.02)Pb(0.98)Te(0.75)Se(0.25) at 773 K and Se-rich K(0.02)Pb(0.98)Te(0.15)Se(0.85) at 873 K, respectively. However, the average ZT was higher in Te-rich compositions than in Se-rich compositions, with the best found in K(0.02)Pb(0.98)Te(0.75)Se(0.25). Such a result is due to the improved electron transport afforded by heavy K doping with the assistance of Se.     

Speciation of metabolites of selenate in rats by HPLC-ICP-MS

The metabolic pathway for and metabolites of selenium (Se) administered intravenously to rats in the form of selenate at a dose of 0.3 mg Se kg-1 body weight were studied by speciating Se in the bloodstream, liver and urine by HPLC-inductively coupled argon plasma mass spectrometry. Selenate was not taken up by red blood cells (RBCs) and disappeared from the bloodstream much faster than selenite, without any change in its chemical form before it disappeared from the plasma. Selenium excreted into the urine after the administration of selenate showed different patterns from those of selenite in both amounts and chemical forms. With the selenate group, the concentration of Se in urine was highest at 0-6 h and the chemical species of Se was selenate at 0-6 h; thereafter a monomethylselenol-related Se compound (MMSe*) and trimethylselenonium ions (TMSe) appeared, selenate not being excreted after 6 h. On the other hand, in the selenite group, the concentration of Se peaked at 6-12 h, and the chemical species of Se were MMSe* and TMSe. Selenate was reduced in vitro on incubation in either a liver homogenate or supernatant fraction, although much more slowly than in the whole body. Selenate was not reduced by glutathione or dithiothreitol. The results suggest that in contrast to selenite, which is taken up by and reduced in RBCs, and then transferred to the liver, approximately 20% of the selenate administered to rats was excreted into the urine without any change in its chemical form with the present dose, and the major portion of selenate was taken up by the liver, reduced and then utilized for the synthesis of selenoproteins or excreted into the urine after being methylated.     

Sensitivities of selenite, selenate, selenomethionine and trimethylselenonium ion in aqueous solution and in blood plasma-ETAAS compared with ICP-MS

Aqueous solutions and blood plasma spiked with selenite (Se(IV)), selenate (Se(VI)), selenomethionine (SeMet) or trimethylselenonium (TMSe) iodide were analyzed by Zeeman-corrected electrothermal atomic absorption spectrometry (ETAAS) using palladium as a chemical modifier, and by inductively coupled plasma mass spectrometry (ICP-MS). Using ETAAS, the sensitivities for Se(IV), SeMet and TMSe in aqueous solution were similar, whereas the sensitivity of Se(VI) was 63% of that value. In blood plasma, the ETAAS sensitivities of Se(IV) and Se(VI) were equal, whereas the sensitivities of SeMet and TMSe were 87 and 56%, respectively, of that value. In contrast, the ICP-MS sensitivities obtained for Se(VI), TMSe and SeMet were between 96 and 98% of that obtained for Se(IV) in aqueous solution and in blood plasma. It is concluded, that ICP-MS is superior to ETAAS as the problem of differences in sensitivity of the selenium species when using ETAAS are not prevalent when using the ICP-MS technique.     

Effects of Micronutrients on Oxidative Stress and Islet Function in Type 1 Diabetes Mellitus Rats： Relationships to Th2 Type Cytokines, Interleukin-4, and Interluekin-10

To observe the effects of the micronutrients on oxidative and autoimmune destruction of islets so as to prevent a person from the onset and development of type 1 Diabetes Mellitus(T1DM),the interleukin-4 and interleukin-10 expressions of lymphocytes in peripheral blood and spleen of T1DM rats were determined by flow cytometry.GSH-Px activity and MDA level in the rats' pancreas were measured using biochemical methods.The insulin contents in serum and β cell insulin secret storage were tested by RIA and IHC,respectively.There was an increase in the percentages of IL-4 and IL-10 positive lymphocytes in the peripheral blood and spleen of the groups of rats supplemented with various combinations of micronutrients(p<0.01 and p<0.05,respectively);the blood glucose concentration decreased(p<0.05);both the functional β cell in islets and the insulin content in pancreatic tissue increased(p<0.05 and p<0.01);the GSH-Px activity and MDA level of pancreas in the rats enhanced and decreased respectively(p<0.01 and p<0.05).The results suggest that micronutrients may alleviate the islet lesions by upregulating the expressions of IL-4 and IL-10 and lowering oxidative stress in diabetic rats.     

Determination of selenium in red blood cells by inductively coupled plasma mass spectrometry (ICP-MS) after microwave digestion

Selenium is an essential trace element and its levels in blood have been widely used for assessing Se status in humans. The aim of this present study is to develop a suitable method for the determination of Se in red blood cells (RBC) using ICP-MS after microwave digestion. The blood samples were obtained from patients with benign prostatic hyperplasia (BPH), who attended urology clinics at the Princess Alexandra hospital, Brisbane, Australia. No apparent polyatomic and matrix interferences were encountered when ⁸²Se isotope was used for the analysis of Se levels in RBC. Whole Blood Seronorm Trace Elements (SERO, Norway) and dogfish muscle (DORM-1, NRCC) were used as reference materials for method validation. The method was rapid and accurate, and ideal for routine analysis of Se in RBC, and in particular for assessing of Se status in humans. This revised version was published online in August 2006 with corrections to the Cover Date.