Review of 15 years of research on ecotoxicology and remediation of land contaminated by agricultural drainage sediment rich in selenium

The consequences of elevated Se accumulation at the Kesterson Reservoir National Wildlife Refuge in the Central Valley of California created adverse effects on wildlife and led to extensive research on the behavior of Se in both the wetland and upland ecosystems. Selenium concentrations in water entering the Kesterson Reservoir averaged 300 microg L(-1). In pond waters 20-30% of the Se was selenate, while only 2% was selenite in the drainage water entering the reservoir. Submerged rooted aquatic plants fed on by water birds were found to contain 18-390 mg Se kg(-1) dry weight. Mosquitofish collected from the San Luis Drain contained 332 mg Se kg(-1), and those collected from the ponds ranged from 339 to 380 mg kg(-1). Livers of water birds had Se concentrations ranging from 19.9 to 127 mg kg(-1). The high concentrations of Se accumulation in the food chain of the wetland strongly suggest that Se bioaccumulation was the cause of death and deformity of embryos of the waterfowl nesting at the wetland habitat. In June 1986, the Kesterson Reservoir was closed to drain-water inputs, and the wetland was transformed to an upland grassland. New remedial plans were proposed. These new plans involved soil, water, and vegetation management to dissipate Se by bioaccumulation and volatilization through soil microorganisms and plants. The investigations of the potential transfer of Se from farm land into the crop and vegetables in the Central Valley indicated that plant tissue Se concentrations generally fall in a nonseleniferous category, except that the highest Se concentration of cotton was at a threshold where toxicity in animals could occur at a relatively low frequency. At the Kesterson upland grassland habitat, average total Se concentrations ranged from 500 to 8000 microg kg(-1) and water-extractable Se ranged from 10 to 700 microg kg(-1) in the top 15 cm of soil and varied greatly, by a factor greater than 100, among soil samples. Uptake of Se by the plants was profoundly affected by the soil available Se concentration, soil moisture, pH, soil salinity, soil sulfate concentration, soil reoxidation condition, kind of plant species, and soil-management practices. The rate of soil Se dissipation at the Kesterson grassland system was from 1% (low methylation rate) to 5% (high methylation rate) Se inventory per year and it will take from 46 to 230 years to bring the soil Se down to a normal level, 4 mg Se kg(-1) soil. However, the Kesterson upland grassland habitat had Se bioaccumulation values less than 10% of those of the previous wetland. The potential food-chain contamination at the existing Kesterson grassland is much less problematic. No negative impact on wildlife has been reported for the upland habitat. Plants may contribute to the Se reoxidation process and be able to reduce the movement of Se in the soil. At the Kesterson grassland, the distribution of soil Se is extremely uneven; high levels of soil Se concentrated only in isolated spots. Therefore, leaching of soil Se is not at an area level. It is unlikely that problems of transport of Se from the Kesterson soil to the adjacent uncontaminated environment by leaching can occur.     

硒对镉诱导的在体大鼠肝细胞DNA损伤、细胞凋亡和细胞增殖的影响

目的　研究亚硒酸钠对氯化镉诱导的大鼠肝细胞DNA损伤、细胞凋亡、细胞增殖周期变化以及DNA相对含量的影响。方法　选用雄性SD大鼠 ,每组 5只 ,用 5 μmol/kg亚硒酸钠分别与5、10和 2 0 μmol/kg的氯化镉联合作用 ,腹腔注射染毒。用单细胞凝胶电泳研究DNA损伤 ,用末端标记法 (TUNEL)和流式细胞术检测大鼠肝细胞凋亡 ,用流式细胞术研究细胞增殖周期和DNA相对含量。结果　 5 μmol/kg的亚硒酸钠对 5、10和 2 0 μmol/kg的氯化镉引起的DNA损伤和细胞凋亡显示出良好的拮抗作用 ,也可使DNA损伤率和细胞凋亡率显著下降。 5 μmol/kg的亚硒酸钠明显抑制5 μmol/kg氯化镉引起的G0 /G1期细胞减少 ,并使 10 μmol/kg和 2 0 μmol/kg氯化镉引起减少的G2 /M期细胞显著增多。 5 μmol/kg的亚硒酸钠还对 10 μmol/kg和 2 0 μmol/kg氯化镉引起的DNA相对含量的下降表现出拮抗作用。结论　一定剂量的亚硒酸钠对一定剂量的氯化镉诱导的DNA损伤、细胞凋亡、细胞增殖周期变化和DNA相对含量下降具有一定的拮抗作用     

镰刀菌毒素DON对心肌细胞膜电位的影响及硒的保护效应

目的 观察镰刀菌毒素单端孢霉烯族化合物脱氧雪腐镰刀菌烯醇(DON)对培养心肌细胞动作电位的影响及亚硒酸钠的保护效应。方法 取新生1～2d龄Wistar大鼠,分离心肌细胞,培养基为80％DMEM与20％小牛血清,于37℃,在含5％CO2与95％空气的培养箱内进行培养,于培养后第4天,引导心肌细胞动作电位为加入毒素前对照,然后向培养基中分别加入50、100和200mg／L DON,以观察不同剂量DON对心肌细胞动作电位的影响。在培养基中加入含0．5mg／L硒的亚硒酸钠,继续培养16h后,观察硒对DON致心肌细胞膜电位改变的保护作用。结果 DON使心肌细胞去极化过程发生改变,动作电位(APA)、最大除极速度(Vmax)、超射(OS)及阈电位(TP)均减小,部分参数指标存在较明显的剂量效应关系。OS在DON为50mg／L时出现增高现象。复极化过程的变化,复极动作电位时程(APD)明显延长;最大舒张电位(MDP)减小;动作电位发放频率(APF)受到明显的抑制,且存在明显的剂量依存关系。在培养基中加入含0．5mg／L硒的亚硒酸钠,继续培养16h后,200mg／LDON对其心肌细胞动作电位的抑制作用明显减弱,但部分参数(APA、Vmax、OS、TP、APD90及APF)没有完全保持在正常对照组水平,亚硒酸钠不能完全对抗DON引起的心肌细胞动作电位的改变。结论 DON能抑制大鼠培养心肌细胞的跨膜电位,初步表明亚硒酸钠可减轻DON对心肌动作电位的影响,呈现明显的保护作用。     

二氧化硒对肺癌细胞增殖、凋亡及端粒酶活性的影响

背景与目的:近年研究表明硒可诱导肿瘤细胞凋亡,并且其与端粒酶活性以及肿瘤的发生密切相关。本研究旨在通过观察二氧化硒(seleniumdioxide,SeO2)对肺腺癌细胞株GLC-82的体外作用,探讨SeO2对肺癌细胞的作用机制,以及细胞凋亡与端粒酶活性之间的关系。方法:采用四甲基偶氮唑蓝(MTT)法测定不同浓度SeO2作用不同时间对肺癌GLC-82细胞生长的抑制作用;用TRAP-PCR-ELISA法检测SeO2作用前后GLC-82细胞端粒酶活性变化;采用流式细胞术(FCM)观察SeO2作用后GLC-82细胞的凋亡率;通过琼脂糖凝胶电泳法观察DNA梯状带;通过光镜和透射电镜观察GLC-82细胞的形态变化。结果:在3、10、30μmol/LSeO2作用下,GLC-82细胞的生长和端粒酶活性明显受抑制,24h时细胞生长抑制率分别为0.7%、12.8%、31.8%,72h时分别达15.1%、51.2%、61.1%;24h时端粒酶活性分别为1.173±0.029、1.127±0.067、1.050±0.098(P<0.05),48h时为1.150±0.026、1.047±0.060、0.950±0.036(P<0.05),未处理组24h和48h时端粒酶活性分别为1.227±0.032、1.167±0.023;流式细胞仪检测二倍体峰前出现凋亡峰,30μmol/LSeO2与GLC-82细胞共育24h、48h、72h后细胞凋亡率分别为0.7%、3.8%、12.1%;琼脂糖凝胶电泳显示细胞凋亡典型梯状条带;SeO2作用后,GLC-82细胞呈典型     

不同碘摄入量地区硒与甲状腺功能关系的流行病学研究

目的　探讨三个不同碘摄入量地区人群硒营养状态与甲状腺功能异常的关系。方法盘山、彰武和黄骅地区分别为低碘、碘充足和高碘地区。将各地区流行病学调查中发现的 32 9例甲状腺功能异常者 (包括临床甲减、亚临床甲减、临床甲亢和亚临床甲亢 )以及同地区的 183名正常人作为研究对象。测定上述研究对象的血清硒、促甲状腺激素 (TSH)和游离甲状腺激素 (FT3及FT4 )水平。结果　盘山、彰武和黄骅地区正常对照组的血清硒中位数分别为 91 4、89 1和 83 2 μg L。各地区甲减、亚甲减及甲亢患者血清硒水平与正常对照比较均无差异 ;只有亚甲亢患者与对照组相比血清硒水平明显下降 (血清硒中位数分别为 82 6 μg L和 87 3μg L) ;且亚甲亢患者与正常对照比较FT3 FT4值下降 ,FT4值升高 ,FT3值无差异。未发现性别和年龄对正常人群血清硒水平有明显影响。各地区正常对照人群血清硒水平与TSH负相关 ,且血清硒≤ 80 μg L组与血清硒 80～ 10 0 μg L及 10 0～ 12 0 μg L组相比TSH值明显升高 (TSH中位数分别为 2 10、1 2 9和 1 2 8mU L)。彰武地区甲状腺过氧化物酶抗体 (TPOAb)阳性的甲状腺功能异常者血清硒与TPOAb滴度负相关 ,且高度阳性组 (TPOAb >6 0 0IU ml)血清硒水平显著低于TPOAb低度和中度阳性组 (血清硒中位     

氢化物原子荧光法测定溪黄草中的硒

目的：建立氢化物原子荧光法测定溪黄草中硒含量的方法。方法：样品经1＋1的硝酸-高氯酸消解完全、6．0mol／L的盐酸预还原后通过氢化物原子荧光法进行测定。结果：方法的检出限为0．02mg／kg，精密度为5．7％，回收率为86％-105％。结论：采用氢化物原子荧光法测定溪黄草中的硒，方法污染少、灵敏度高、准确度较好。     

湖北恩施州宽叶缬草含硒量测定

采用原子荧光法测定湖北恩施州3个地区的宽叶缬草及土壤样品的硒含量,发现当地宽叶缬草硒含量明显高于其它地区样品,可作为一项开发成道地药材的依据和有效鉴定评价指标。     

富硒保健食品的研究与开发

生物有机硒安全、更易被人体吸收和利用。选用不同生物具有同化无机硒为有机硒的能力，可生产一系列富硒保健品。研究和开发富硒保健品对人体健康具有重要意义。     

Selenium content of human milk,cow's milk and cow's milk infant formulas

The selenium content of human milk, cow's milk and cow's milk infant formula were estimated by instrumental neutron activation analysis. The highest values were found in 3 samples of human colostrum (524–865×10^-9 g/g dry weight). There was a significant decrease with increasing time post partum. Mature human milk exhibited a selenium content of 230±79×10^-9 g/g dry weight.The selenium content of 45 samples of cow's milk from the north-western area of Germany was 200±39×10^-9 g/g dry weight. While there was no significant difference between the values of mature human milk and of cow's milk, cow's milk infant formula exhibited significantly (P<0.01) lower values than human milk. The average selenium content of 107 samples of 10 different commercially available fluid and powdered cow's milk infant formulas (range: 18–171×10^-9 g/g dry weight) amounted to about only one third of that in mature human milk.With support of the Deutsche Forschungsgemeinschaft     

Plasma glutathione peroxidase after selenium supplementation in patients with reduced selenium state

The plasma glutathione peroxidase (GSHPx) activity was measured in normal adults and children and in patients with reduced selenium state because of dietary treatment of metabolic diseases (phenylketonuria or maple-syrup-urine disease) before and after selenium supplementation. Besides GSHPx (measured with t-butyl hydroperoxide, cumene hydroperoxide and hydrogen peroxide as acceptor substrates) the activity of glutathione S-transferase was estimated in plasma. Plasma GSHPx activity in healthy children was significantly lower than in healthy adults. In 11 dietetically treated patients with phenylketonuria or maple-syrup-urine disease the plasma GSHPx was reduced to about 17% of the values of healthy children of the same age. No glutathione S-transferase activity could be found in plasma of children in normal or reduced Se state.During administration of yeast rich in Se (200g Se/d) for 90 days 2 healthy adults showed no significant change of plasma GSHPx activity. During Se supplementation (75–100g Se/d) for 120–163 days 5 dietetically treated patients with PKU or MSUD exhibited a significant increase of plasma GSHPx activity within 2 days. The values reached a plateau after 1 to 3 weeks of supplementation and remained at this level within the following 4 to 5 months. Therefore, the activity of plasma glutathione peroxidase can be used as an indicator of short-term changes of selenium intake in selenium deficient individuals.Abbreviations (PKU) Phenylketonuria - (MSUD) maple-syrup-urine disease - (GSHPx) glutathione peroxidase - (t-BOOH) t-butyl hydroperoxide - (COOH) cumene hydroperoxide - (H₂O₂) hydrogen peroxide - (GSH) reduced glutathione With support of the Deutsche Forschungsgemeinschaft