硒与胃癌关系的研究

用Ames方法测定了硒和硒酵母对MNNG诱发TA100致突变作用的抑制效果,并用原子吸收分光光度计测定12例浅表性胃炎(SG)、17例萎缩性胃炎(CAG)、6例不典型增生(Dys)和12例胃癌(GC)病人的头发、血液和部分患者胃液中的硒含量,并用气相-热能分析仪测定了胃液中的亚硝胺含量。结果表明:硒和硒酵母有抑制MNNG对TA100的致突变作用,抑制率分别为66.5％和37.9％;患者的血清硒、发硒和胃液硒的含量随胃粘膜病变程度的加重而降低;SG与GC之间差异非常显著(p<0.01),而亚硝胺的含量SG明显低于CAG、Dys及GC。应用硒酵母给予患者补充硒(150μg/d),观察到血硒含量有明显提高,MnSOD及LPO下降,NK细胞活性增加和胃镜病理活检有好转的变化。     

Optimization for Preservation of Selenium in Sweet Pepper Under Low-Vacuum Dehydration

Response Surface Methodology (RSM) was used for optimizing the drying technology of sweet pepper under low-vacuum. It was found that pH value has greater influence on the organic Se index, while drying temperature has greater effect on the chlorophyll index. The optimized parameters of drying temperature, pH value and blanching time were obtained, respectively.     

阳极泥处理工艺优化实践

介绍江西铜业股份有限公司贵溪冶炼厂 (以下简称贵冶 )铜阳极泥杂质成分变化对工艺的影响 ,提出了优化脱除铋、锑、砷、硒杂质的工艺和措施 ,增强了工艺处理与适应能力     

Chromate ion adsorption by agricultural by-products modified with dimethyloldihydroxyethylene urea and choline chloride

The use of cellulose-containing agricultural by-products modified with the cross-linking reagent dimethyloldihydroxyethylene urea (DMDHEU) and the quaternary amine, choline chloride, as anion exchange resins, has not been reported. The objective of the present study was to convert the readily available by-products, soybean hulls, sugarcane bagasse and corn stover to functional anion exchange resins using DMDHEU and choline chloride. Optimization of the modification method was achieved using soybean hulls as a substrate. The optimized method was additionally used to modify sugarcane bagasse and corn stover. Adsorption efficiency results with chromate ion showed that modification with both DMDHEU and choline chloride was required for the highest efficiencies. Adsorption capacities of the modified by-products were determined using chromate ion and found to be 1.97, 1.61 and 1.12 mmol/g for sugarcane bagasse, corn stover and soybean hulls, respectively. Competitive adsorption studies were conducted at 10 and 50 times US Environmental Protection Agency (US EPA) limits for arsenic, chromium and selenium in a simulated wastewater at pH 7. The results showed preferential adsorption of chromate ion over arsenate or selenate ion. Estimated product costs for the three resins ranged from $0.88/kg to $0.99/kg, which was considerably lower than the market costs for the two commercial anion exchange resins QA-52 and IRA-400 also used in this study. DMDHEU/choline chloride modification of the three by-products produced an anion exchange resin with a high capacity to adsorb chromate ion singly or competitively in the presence of other anions from aqueous solutions.     

Environmental contaminants and biomarker responses in fish from the Rio Grande and its U.S. tributaries: spatial and temporal trends

We collected, examined, and analyzed 368 fish of seven species from 10 sites on rivers of the Rio Grande Basin (RGB) during late 1997 and early 1998 to document temporal and geographic trends in the concentrations of accumulative contaminants and to assess contaminant effects on the fish. Sites were located on the mainstem of the Rio Grande and on the Arroyo Colorado and Pecos River in Texas (TX), New Mexico (NM), and Colorado. Common carp (Cyprinus carpio) and largemouth bass (Micropterus salmoides) were the targeted species. Fish were examined in the field for internal and external visible gross lesions, selected organs were weighed to compute ponderal and organosomatic indices, and samples of tissues and fluids were obtained and preserved for analysis of fish health and reproductive biomarkers. Whole fish from each station were composited by species and gender and analyzed for organochlorine chemical residues and elemental contaminants using instrumental methods, and for 2,3,7,8-tetrachloro dibenzo-p-dioxin-like activity (TCDD-EQ) using the H4IIE rat hepatoma cell bioassay. Overall, fish from lower RGB stations contained greater concentrations of organochlorine pesticide residues and appeared to be less healthy than those from sites in the central and upper parts of the basin, as indicated by a general gradient of residue concentrations and biomarker responses. A minimal number of altered biomarkers and few or no elevated contaminant concentrations were noted in fish from the upper RGB. The exception was elevated concentrations [up to 0.46 microg/g wet-weight (ww)] of total mercury (Hg) in predatory species from the Rio Grande at Elephant Butte Reservoir, NM, a condition documented in previous studies. Arsenic (As) and selenium (Se) concentrations were greatest in fish from sites in the central RGB; Se concentrations in fish from the Pecos River at Red Bluff Lake, TX and from the Rio Grande at Langtry, TX and Amistad International Reservoir, TX exceeded published fish and wildlife toxicity thresholds. In the lower RGB, residues of p,p'-DDT metabolites (相似文献   

Selenium content in the pilchard of the Adriatic Sea

The selenium content was determined in the muscle tissue (M. longissimus dorsi) of the pilchard (Clupea pilchardus). The fishes originated from catches at two localities, the mid-and northern Adriatic Sea, during two seasons—spring and autumn. The selenium content was determined by the hydride procedure of atomic absorption spectrophotometry, with the results being expressed as wet weight (ww). Four groups of the analysed samples indicated differences in the selenium content, depending on the location and time (season) of the catch. The highest selenium content was found in the pilchard of the mid-Adriatic Sea in spring (712.7 ±23.7 ng/g wet weight) and the lowest in the pilchard of the northern Adriatic Sea caught in autumn (472.7± 34.7 ng/g ww.). Regardless of seasonal differences and/or geographical aspects, the pilchard of the Adriatic Sea contains on average 580 ng Se/g ww and may be considered a significant source of this essential micronutrient.     

Strategies to lower methyl mercury concentrations in hydroelectric reservoirs and lakes: A review

Mercury (Hg) concentrations in fish in lakes are elevated due to increased global cycling of Hg. A special case of elevated Hg concentrations in fish occurs in new hydroelectric reservoirs because of increased rates of converting Hg in the environment into methyl mercury (MeHg). People and wildlife that eat fish from hydroelectric reservoirs have an elevated risk of accumulating too much MeHg. Demand for electrical energy is leading to the creation of new reservoirs. In 2005, Canada derived 60% of its electricity from hydroelectric reservoirs. As a result, hydroelectric companies and governing agencies are exploring strategies to lower MeHg contamination. Strategies may involve lowering the source of Hg before flooding, the rate of Hg methylation, or MeHg bioaccumulation and biomagnification. Possible strategies reviewed in this article include selecting a site to minimize impacts, intensive fishing, adding selenium, adding lime to acidic systems, burning before flooding, removing standing trees, adding phosphorus, demethylating MeHg by ultraviolet light, capping and dredging bottom sediment, aerating anoxic bottom sediment and waters, and water level management. A preventative strategy is to limit the flooded area, especially wetland areas. Flooded upland areas that contain less carbon produce MeHg for a shorter time than wetland areas. Run-of-the-river reservoirs contain lower MeHg concentrations than reservoirs that flood vast areas, at the cost of exporting MeHg downstream. Managing water levels to flush systems during times of peak MeHg production may have benefits for the reservoir, but also transports MeHg downstream. Intensive fishing can lower MeHg in food webs by increasing fish growth rate. Additions of selenium can lower MeHg bioaccumulation, but the mechanisms are not well established and excess selenium causes toxicity. Liming can lower fish Hg concentrations in lakes acidified with sulphuric and nitric acid. Burning before flooding can lower the production of MeHg, but MeHg bioaccumulation may increase. The most promising strategy will be one that is agreeable to all affected people.     

氢化物发生原子荧光法测水中痕量硒

本文研究了用氢化物发生原子荧光法测水中痕量硒。本方法是在盐酸介质中,以硼氢化钾作还原剂,将硒转化为硒化氢。以高纯氩气作为载气将硒化氢从母液中分离,并导入石英炉原子化器中原子化。以硒特种空心阴极灯作激发光源,使硒原子发出荧光,荧光强度在一定范围内与硒的含量成正比。本方法简便、灵敏度高,相关系数r=0.9999,检出限为0.0677μg/L。     

Selenium concentration and speciation in biofortified flour and bread: Retention of selenium during grain biofortification,processing and production of Se-enriched food

The retention and speciation of selenium in flour and bread was determined following experimental applications of selenium fertilisers to a high-yielding UK wheat crop. Flour and bread were produced using standard commercial practices. Total selenium was measured using inductively coupled plasma-mass spectrometry (ICP-MS) and the profile of selenium species in the flour and bread were determined using high performance liquid chromatography (HPLC) ICP-MS. The selenium concentration of flour ranged from 30 ng/g in white flour and 35 ng/g in wholemeal flour from untreated plots up to >1800 ng/g in white and >2200 ng/g in wholemeal flour processed from grain treated with selenium (as selenate) at the highest application rate of 100 g/ha. The relationship between the amount of selenium applied to the crop and the amount of selenium in flour and bread was approximately linear, indicating minimal loss of Se during grain processing and bread production. On average, application of selenium at 10 g/ha increased total selenium in white and wholemeal bread by 155 and 185 ng/g, respectively, equivalent to 6.4 and 7.1 μg selenium per average slice of white and wholemeal bread, respectively. Selenomethionine accounted for 65–87% of total extractable selenium species in Se-enriched flour and bread; selenocysteine, Se-methylselenocysteine selenite and selenate were also detected. Controlled agronomic biofortification of wheat crops for flour and bread production could provide an appropriate strategy to increase the intake of bioavailable selenium.