淡水微囊藻毒素毒理学研究进展

微囊藻毒素是由淡水蓝藻产生的一类具有肝毒性的生物活性物质。它能够抑制蛋白磷酸酶1和蛋白磷酸酶2A的活性,使细胞内的蛋白磷酸化和去磷酸化失衡。微囊藻毒素能够对人体产生一系列的危害,如肝毒性、肾毒性、肠毒性和促癌作用等。     

我国水源水及饮用水中微囊藻毒素的污染现状及影响因素研究

微囊藻毒素是地表水中常见的藻毒素,广泛分布于全世界各种类型的水域。目前已知微囊藻毒素-LR具有极强的肝毒性,达到极低浓度即可对人体健康造成严重危害,因此对于集中式供水水源地正遭受微囊藻毒素污染的报道尤为引人关注。本文综述了近年来关于我国水源水及出厂水中微囊藻毒素的污染现状及与疾病的关系,探讨了微囊藻毒素浓度变化的相关影响因素,为加强对水源水及饮用水中微囊藻毒素的监测和治理,保护人民群众的身心健康提供科学的依据。     

微囊藻毒素的毒性以及水生生物的富集作用

微囊藻毒素是微囊藻等淡水藻类产生的一类具有生物活性的环状七肽物质 ,它能抑制蛋白磷酸酶 1和蛋白磷酸酶 2A的活性 ,打破细胞内蛋白磷酸化 脱磷酸化的平衡 ,引起肝损伤甚至肝坏死。而且它是强促癌剂。然而 ,其毒性及富集作用很少受到人们的重视。本文拟综述微囊藻毒素的毒性及其生物富集作用     

宁波市部分水域微囊藻毒素-LR污染状况调查

微囊藻毒素(Microcystin,MC)是一组环状七肽结构,主要由蓝藻产生,具有肝毒性。随着环境污染加重和水体富营养化加剧,微囊藻毒素引起的中毒事件时有报道。WHO《饮用水水质准则》规     

微囊藻毒素-LR毒性的分子机制研究进展

本文回顾了微囊藻毒素-LR细胞毒性的分子机制研究进展,介绍了微囊藻毒素-LR通过抑制PP2A 活性调节细胞生命活动的主要毒性机制,简述了其与DNA 损伤、细胞骨架破坏的关系,印证了微囊藻毒素-LR的强细胞毒性.开展微囊藻毒素-LR毒性的研究对人类健康具有十分重要的意义.     

微囊藻毒素遗传毒性研究进展

微囊藻毒素是淡水水体污染物中对人体健康威胁最大的一种细胞内毒素,主要表现为肝毒性[1],长期接触可损害细胞遗传物质。目前主要用微核试验、Ames试验、彗星试验等体内外试验检测其遗传毒性。作者综述了微囊藻毒素遗传毒性研究的试验方法、检测终点,并对其可能机制进行了初步的探讨。     

微囊藻毒素肝毒性分子机制研究进展

微囊藻毒素(microcystin,MC)是淡水富营养化水体最常见的一类藻类毒素。它具有嗜肝性,主要在肝脏被转运、吸收和积累。MC对肝脏的毒性作用已有大量研究,尤其是对肝毒性作用的分子机制研究。本文就MC所引起的急慢性肝毒性的分子机制的研究进展进行综述。     

上海淀山湖、黄浦江水系浮游藻类及藻类毒素的动态研究

通过对淀山湖、黄浦江水系浮游藻类的种群构成和蓝藻毒素的季节变化进行周年监测，发现淀山湖藻类及其毒素的污染具有明显的季节性，７～９月份蓝藻大量繁殖，形成了一年中污染的高峰。优势种群已由隐藻被毒性较高的蓝藻所取代，而蓝藻中占优势的铜绿微囊藻、水华鱼腥藻等能产生一种具有强烈肝毒性的短肽，称为微囊藻毒素。应用ＥＬＩＳＡ方法对淀山湖水中的微囊藻毒素进行测定，结果表明水体中微囊藻毒素与蓝藻的变化规律呈正相关，夏、秋季水中毒素出现高峰，最高值达５５．４ｎｇ／ｍｌ，说明淀山湖藻类毒素的污染较为严重。通过对水体总磷、总氮、叶绿素ａ、ｐＨ值等因素的分析，讨论了影响该水系营养水平和藻类生长的主要因素。     

上海淀山湖,黄浦江水系浮游藻类及藻类毒素的动态研究

通过对淀山湖，黄浦江水系浮游藻类的种群构成和蓝藻毒素的季节变化进行周年监测，发现淀山湖藻类及其毒素的污染具有明显的性，７－９月份蓝藻大量繁殖，形成了一年中污染的高峰，优势种群已由隐藻毒性较高的蓝藻所取代，而蓝藻中占优势的铜绿微囊藻，水华鱼腥藻等能产生一种具有强烈肝毒性的短肽，称为微囊藻毒素。     

微囊藻毒素对鱼类免疫毒性的研究进展

微囊藻毒素(microcystins,MCs)是富营养化水体中最常见、毒性最强、研究最广泛的一类藻毒素,已经引起了广泛的关注。MCs除具有典型的肝毒性外,还具有免疫毒性。笔者主要从免疫器官的病理变化、免疫细胞、免疫相关酶以及基因等方面综述了MCs对鱼类免疫毒性的研究现状,进而系统梳理了MCs对鱼类的免疫毒性作用机制,可为有效预警环境中MCs的潜在风险提供支持。     

酶联免疫吸附试验在微囊藻毒素检测中的应用进展

微囊藻毒素(MCs)是蓝绿藻属产生的一类密切相关的环状七肽毒素,其毒性主要表现在特异性抑制细胞内的蛋白磷酸酶(分别为PP1和PP2A)。目前有关微囊藻毒素分析检测的研究方法有高效液相色谱(HPLC)、质谱(LC-MS)、蛋白磷酸酶抑制试验(PPIA)和酶联免疫吸附试验(ELISA)等,本文主要介绍了应用酶联免疫吸附法检测MCs的研究进展,并对ELISA在天然水中检测微囊藻毒素的应用前景进行了展望。     

藻毒素对实验性大鼠肝癌的促进作用

目的 研究藻毒素在实验性大鼠肝癌诱导过程中的促进作用。方法 以二乙基亚硝胺(DEN)为启动剂，藻毒素为促进剂，构建大鼠肿瘤促进模型(Solt-Farber模型)，观察肝脏病理形态改变，分别运用免疫组化法和RT-PCR、原位杂交法检测肝细胞中GSTPi蛋白和GSTPi mRNA表达情况。结果 实验组动物肝脏产生结节性增生灶，藻毒素单独作用不能诱导GSTPi mRNA及蛋白表达，但能够促进DEN诱导产生的GSTPi mRNA及蛋白表达，使其表达增加，并具有一定的剂量-反应关系。结论 藻毒素对实验性大鼠肝癌的发生具有促进作用，提示具有促癌活性。     

Bioaccumulation and detoxication of nodularin in tissues of flounder (Platichthys flesus), mussels (Mytilus edulis,Dreissena polymorpha), and clams (Macoma balthica) from the northern Baltic Sea

Cyanobacterial hepatotoxin accumulation in mussels (Mytilus edulis, Dreissena polymorpha), clam (Macoma balthica), and flounder (Platichthys flesus) tissues was measured. Flounder were caught with gillnets from the western Gulf of Finland on 21 August 1999, 25 July 2000, and 25 August 2000. Blue mussels were collected from: (1) a steel cage at a depth of 3 m on 20 August 1999, (2) an enclosure at depths of 3-5 m, and (3) an artificial reef (wreck at 25-30 m) in the western Gulf of Finland between June and September 2000. Furthermore, blue mussels were collected from two sites between August and October 2000: south of the town of Hanko at depths of 5 and 20 m in the western Gulf of Finland and south of the city of Helsinki at a depth of 7 m in the central Gulf of Finland. M. balthica and D. polymorpha were collected at a depth of 12 m from Russian waters in the eastern Gulf of Finland on 1-4 August 2000. The samples were analyzed for the cyanobacterial hepatotoxins nodularin (NODLN) and microcystins (MCs) using enzyme-linked immunosorbent assay (ELISA), liquid chromatography-mass spectrometry (LC-MS), and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). ELISA indicated a time-dependent accumulation of hepatotoxins in flounder liver up to 400 +/- 10 (SD) microg/kg on 25 August 2000. No hepatotoxins were detected in flounder muscle samples. In blue mussels, collected from an enclosure 3-5 m deep in the western Gulf of Finland on 23 August 2000, ELISA indicated cyanobacterial hepatotoxins up to 1490 +/- 60 microg/kg dry wt. Blue mussels collected from the other sites contained less cyanobacterial hepatotoxins (40-130 microg/kg dry wt). Clams and mussels from Russian waters contained cyanobacterial hepatotoxin at about 100-130 microg/kg dry wt. Total hepatotoxin levels in mussels from enclosures decreased from August to September, indicating at least partial detoxication/depuration of the toxins. LC-MS verified the presence of NODLN in mussels and flounder. Typical detoxication conjugates were observed by MALDI-TOF-MS in mussel samples collected during August 2000. In deeper-living wreck mussels cyanobacterial hepatotoxin levels continued to increase, from August to September, indicating that portions of cyanobacterial hepatotoxins reach the sea floor. NODLN bioaccumulation is a constant phenomenon in the area.     

消除水中蓝绿藻肝毒素研究进展

近年来蓝绿藻水华日趋普遍,而由其产生的微囊藻肝毒素已证实具有很强的肝毒性,与人类健康损害密切相关,因此饮用水中毒素的去除受普遍关注。学者们对应用各种物理、化学、生物学的方法去除ＭＣ的效果进行了广泛评价,结果显示：活性炭、膜处理藻细胞内外的毒素效果均较好;臭氧、氯化、紫外线等去除细胞外毒素效果较好,但应用剂量不足时,有可能起细菌裂,毒素释放。     

Microcystin Removal by a Naturally-Occurring Substance: Pumice

Microcystins (MCs) are among the most prevalent and potent of the cyanobacterial toxins (cyanotoxins) and their potential occurrence in waters required for drinking has prompted investigations into remedial water treatments for their removal. We have investigated the suitability of local pumice, as a possible low-cost material for environmental application for the removal of cyanotoxins. Adsorption and desorption rates of pure MC-LR, one of the most common and toxic forms of MC and with crude extracts of the cyanobacterium. Microcystis aeruginosa containing MCs, were studied using bench-scale, pumice-packed glass columns, with good retention of the toxins being achieved. Research is in progress to optimize MC removal and to determine the applicability of pumice as a treatment material for cyanotoxin removal.     

Spatial and temporal variations of microcystins in hepatopancreas of a freshwater snail from Lake Taihu

In this paper, spatial and temporal variations of three common microcystins (MC-RR, MC-YR, and MC-LR) in the hepatopancreas of a freshwater snail (Bellamya aeruginosa) were studied monthly in two bays of Lake Taihu. Microcystins (MCs) concentration in hepatopancreas was quantified by liquid chromatography-mass spectrometry (LC-MS). The MCs concentrations in hepatopancreas were higher at Site 1 than those at other sites, which was in agreement with the changes of intracellular MCs concentrations in the water column. There was a significant correlation between MCs concentrations in the hepatopancreas and that in the seston, suggesting that spatial variances of MCs concentrations in hepatopancreas among the five sites were due to spatial changes of toxic Microcystis cells in the water column. PCCA indicates that in addition to Microcystis, other factors (e.g., water temperature) also substantially affected the accumulation of MCs in hepatopancreas of the snail.     

Effects of microcystins on fish

Microcystins (MCs) are hepatotoxic heptapeptides released into water during or on senescence of cyanobacterial blooms. This review details the different effects of the MCs on fish and discusses their potential consequences in aquatic food webs. In early life stages, exposure to MCs causes, in a dose-dependent manner, perturbations to embryonic hatching, decrease in survival and growth rate, as well as histopathological effects (enlarged and opaque yolk sac, small head, curved body and tail, hepatobiliary abnormalities, ultrastructural alterations in hepatocytes, heart rate perturbations). In adults and juveniles, field and experimental studies demonstrated that after ingestion MCs accumulate mainly in liver but can also be found in muscle and viscera. Microcystin exposure has been shown to affect growth rate and osmoregulation, increase liver enzyme activities in the serum and heart rate, modify behavior, and exert histopathological effects in the liver, intestine, kidneys, heart, spleen, or gills, but the degree to which these effects were seen depends on the exposure route. The detoxication pathway of MCs in fish begins with a conjugation reaction to glutathione catalyzed by glutathione S-transferases, and this is comparable to the reaction demonstrated in other organisms, from plants to mammals. It appears that MC concentrations found in nature can potently affect several trophic levels in the aquatic ecosystems, in particular by inducing failure of sensitive stages (e.g., fish fry) to develop and accumulating in the food chains. The need of further quantitative studies on the sublethal effects, accumulation, and fate of MCs in aquatic food chains still remains.     

The use of experimental studies to reveal suspected neurotoxic chemicals as occupational hazards: acute and chronic exposures to organic solvents.

The nervous system differs from many other body organs by its central control of vital functions and its low regeneration capacity. Organic solvents have, as a group, been suspected to have neurotoxic effects. Because of their similar physical properties and the fact that in industrial uses, they are often present in various mixtures, organic solvents have also been regarded, unfortunately, to induce common neurotoxic effects. However, it is evident from experimental studies using specified exposure conditions that different organic solvents have very diverse neurotoxic effects and also that the toxic mechanism may differ between acute and chronic exposure. No specific method used to describe a neurotoxic effect or single toxic response can be used for the overall occupational risk assessment of all organic solvents. Each solvent has to be considered as having its own unique toxic effects.     

Self discipline and obesity in Bangkok school children

Background

In 2004, the Ministry of Health issued the policy of decentralising microscopy services (MCs) to one third of all township hospitals in China. The study was conducted in Gansu Province, a poor western one in China. Ganzhou was one county in Gansu Province. Ganzhou County was identified as a unique case of further decentralisation of tuberculosis (TB) treatment services in township hospitals. The study evaluated the impact of the MC policy on providers and patients in Gansu Province. The second objective was to assess the unique case of Ganzhou County compared with other counties in the province.

Methods

Both quantitative and qualitative methods were used. All 523 MCs in the province completed an institutional survey regarding their performance. Four counties were selected for in-depth investigation, where 169 TB suspects were randomly selected from the MC and county TB dispensary registers for questionnaire surveys. Informant interviews were conducted with 38 health staff at the township and county levels in the four counties.

Results

Gansu established MCs in 39% of its township hospitals. From January 2006 to June 2007, 8% of MCs identified more than 10 TB sputum smear positive patients while 54% did not find any. MCs identified 1546 TB sputum smear positive patients, accounting for 9% of the total in the province. The throughputs of MCs in Ganzhou County were eight times of those in other counties. Interviews identified several barriers to implement the MC policy, such as inadequate health financing, low laboratory capacity, lack of human resources, poor treatment and management capacities, and lack of supervisions from county TB dispensaries.

Conclusion

Microscopy centre throughputs were generally low in Gansu Province, and the contribution of MCs to TB case detection was insignificant taking account the number of MCs established. As a unique case of full decentralisation of TB service, Ganzhou County presented better results. However, standards and quality of TB care needed to be improved. The MC policy needs to be reviewed in light of evidence from this study.     

Assessing potential health risks from microcystin toxins in blue-green algae dietary supplements

The presence of blue-green algae (BGA) toxins in surface waters used for drinking water sources and recreation is receiving increasing attention around the world as a public health concern. However, potential risks from exposure to these toxins in contaminated health food products that contain BGA have been largely ignored. BGA products are commonly consumed in the United States, Canada, and Europe for their putative beneficial effects, including increased energy and elevated mood. Many of these products contain Aphanizomenon flos-aquae, a BGA that is harvested from Upper Klamath Lake (UKL) in southern Oregon, where the growth of a toxic BGA, Microcystis aeruginosa, is a regular occurrence. M. aeruginosa produces compounds called microcystins, which are potent hepatotoxins and probable tumor promoters. Because M. aeruginosa coexists with A. flos-aquae, it can be collected inadvertently during the harvesting process, resulting in microcystin contamination of BGA products. In fall 1996, the Oregon Health Division learned that UKL was experiencing an extensive M. aeruginosa bloom, and an advisory was issued recommending against water contact. The advisory prompted calls from consumers of BGA products, who expressed concern about possible contamination of these products with microcystins. In response, the Oregon Health Division and the Oregon Department of Agriculture established a regulatory limit of 1 microg/g for microcystins in BGA-containing products and tested BGA products for the presence of microcystins. Microcystins were detected in 85 of 87 samples tested, with 63 samples (72%) containing concentrations > 1 microg/g. HPLC and ELISA tentatively identified microcystin-LR, the most toxic microcystin variant, as the predominant congener.