【作者】 罗磊；

【导师】 李时恩；

【作者基本信息】 郑州大学 ， 劳动卫生与环境卫生学， 2009， 硕士

【摘要】 铅是人类在工业生产和生活环境中广泛接触的一种金属元素,国际癌症研究机构(IARC)早已将铅列为人类可能致癌物。最常见的接触铅及其化合物的行业是铅锌等金属冶炼行业,其工作场所中存在多种职业性有害因素,如粉尘、铅尘、有毒气体、噪声、高温和振动等。长期暴露于高铅环境下,会对工作在一线的铅冶炼作业工人身体健康带来极大危害。目前职业性铅中毒的机制尚不十分清楚,现有的证据表明铅诱导产生的活性氧族能够影响信号传导、攻击细胞膜和直接造成DNA损伤等,其中最重要的一种机制就是铅诱导的活性氧族引起细胞的氧化损伤,继而影响机体的正常功能。热应激蛋白(Heat stress proteins,HSPs)是细胞在一些应激条件下(如接触重金属毒物等)所产生的一组具有高度保守性的蛋白质。热应激蛋白70(Heat stressprotein70,HSP70)是其中最常见、最主要的一种,其在细胞的损伤和修复、对外来刺激产生氧化应激过程中发挥着重要作用。通过临床试验和构建动物模型研究发现,多种应激因素如高温,低氧环境和有毒物质等均可导致机体HSP70水平升高。由于HSP70这种对外界刺激的高敏感性,目前越来越多的研究集中在HSP70足否能作为一种有效的生物标志用来评价职业性有害因素对机体带来的不良生物学效应。本研究以铅冶炼作业工人为研究对象,进一步阐述职业性铅接触与机体氧化应激之间的关系,明确不同工种铅冶炼工人HSP70表达水平变化及其意义,初步探讨HSP70作为环境铅污染及铅接触人群监控的生物标志的可行性。研究对象与方法1研究对象选取某铅冶炼厂铅冶炼作业工人155人作为铅接触组,其中原料工段14人、富氧底吹炉工段39人、鼓风炉工段42人、电解精炼工段49人和成品工段11人,另选取该厂管理、后勤和销售等不接触铅的人员56人作为对照组。2研究方法本研究选取铅冶炼作业工人155人作为铅接触组,不接触铅的作业工人56人作为对照组,所选研究对象均为男性。采集全部研究对象外周静脉血5ml和一次性晨尿100ml,采用ELISA试剂盒测定血浆HSP70含量,并对铅接触组和对照组作业工人血铅、尿铅含量及脂质过氧化指标(SOD、GSH-Px、CAT和MDA含量)进行测定。2.1所有研究对象均接受问卷调查,内容包括个人一般状况、铅作业史、既往病史和家族史等,并收集与本研究中铅冶炼作业工人有关的职业流行病学资料。2.2工作场所空气中铅尘铅烟浓度测定:采用火焰原子吸收光谱法,按照《工作场所空气有毒物质测定:铅及其化合物—火焰原子吸收光谱法》(GBZ/T160.10-2004)进行。2.3采用酶联免疫吸附试验(Enzyme linked immunosorbent assay,ELISA)法测定血浆HSP70含量,严格按照试剂盒说明书进行操作。2.4血铅含量测定:采用石墨炉原子吸收光谱法,按照《血中铅、镉的石墨炉原子吸收光谱测定方法》(WS/T174-1999)进行。2.5尿铅含量测定:采用微分电位溶出法,按照《尿中铅微分电位溶出测定方法》(WS/T19-1996)进行。2.6超氧化物歧化酶(SOD)含量测定:采用黄嘌呤氧化酶法,严格按照试剂盒说明书进行操作。2.7谷胱甘肽过氧化物酶(GSH-Px)含量测定:采用二硫代双硝基苯甲酸法,严格按照试剂盒说明书进行操作。2.8过氧化氢酶(CAT)含量测定:采用钼酸铵比色法,严格按照试剂盒说明书进行操作。2.9丙二醛(MDA)含量测定:采用硫代巴比妥酸比色法,严格按照试剂盒说明书进行操作。2.10统计学分析:用SPSS10.0软件对数据进行统计分析,检验水准α=0.05。结果1工作场所空气中铅含量测定结果显示,短时间接触浓度(short term exposurelimit concentration,STEL)范围是0.101mg/m~3～1.380 mg/m~3,时间加权平均浓度(time weighted average concentration,TWA)范围是0.045mg/m~3～0.73 8mg/m~3,均超过国家职业卫生限值。2 ELISA结果显示,与对照组相比,铅接触组作业工人血浆中HSP70含量比对照组高出约6倍(P＜0.05)。3铅接触组血铅、尿铅含量均明显高于对照组(P＜0.05)。4铅接触组作业工人血清中GSH-Px和CAT含量要低于对照组(P＜0.05),而MDA含量则高于对照组(P＜0.05)。5对HSP70含量、血铅含量和尿铅含量之间的相关关系进行分析,结果显示,HSP70含量和血铅、尿铅含量之间均有相关性,相关系数分别为0.322和0.319(P＜0.05);血铅含量和尿铅含量之间的相关性更大,其相关系数为0.883(P＜0.05)。结论1铅冶炼作业工人铅接触水平与机体氧化损伤密切相关,铅可以诱导机体发生脂质过氧化,降低机体的抗氧化能力。2 HSP70可作为职业性铅接触的一种敏感的生物标志。更多还原

【Abstract】 Lead is a naturally occurring metal that exists widely in the environment and is used in several industries.The Internation Agency for Research on Cancer(IARC) and other investgators have concluded from experimental data that lead is a potential carcinogen in human.Occupational exposure to lead occurs in smelting of ores for lead,zinc and other metals.There are many kinds of occupational hazards in the workplace such as total dust,lead dust,toxic metals,toxic gases,noise,heat stress,vibration and so on.Growing levels of lead pollution represent a serious health hazard to the occupational workers.The molecular mechanisms of lead toxicity are not yet fully understood.Current evidence indicates that lead-induced reactive oxygen species(ROS) act on signaling pathways,promote cell proliferation and cause direct DNA damage.ROS-induced by lead exposure are capable of causing an oxidative stress that can damage or modulate a variety of cellular macromolecules and mechanisms.Heat stress proteins(HSPs) are a family of highly conserved proteins that are induced by a number of stresses including toxic metals.Heat stress protein 70(HSP70) are commonly conserved stress-response proteins which play a central role in cellular repair and adaptation to stress.The role of HSP70 has been studied in a variety of clinically relevent animal models or conditions,such as hyperthermia,hypoxia, exposure to toxic chemicals and so on.At present,HSP70 is thought as a useful biomarker to appraise adverse biological effect induced by different environmental stressors.The objectives of this research are to analyze the relationship between lead exposure and oxidative injury,to investigate changes of HSP70 expression induced by lead exposure.Also an attempt was made to determine whether HSP70 might to be effective biomarker of occupational hazards.Subjects and Methods1 SubjectsThere were 155 workers exposed to lead as the occupational exposed group in this research,including 14 workers of the raw material section,39 workers of the bottom blowing oxygen-rich furnace section,42 workers of the blast smelting furnace section,49 workers of the electrolytic refining section,and 11 workers of the product section.Meanwhile 56 workers unexposed to lead were selected as the control group.2 MethodsIn this research,the subjects consist of 155 workers exposed to lead as the occupational exposed group and 56 workers nonexposed as control group.All subjects were male.Peripheral vein blood and urine was obtained from all subjects.An enzyme linked immunosorbent assay(ELISA) was used to detect the plasma levels of HSP70.Lipid peroxidation(LPO) kit was used to detect the blood serum concentrations of SOD,GSH-Px,CAT and MDA.2.1 All subjects were investigated by questionaire including personal information, history of exposure to lead,past medical history and so on.The occupational epidemiological investigation of the workers exposed to lead was performed.2.2 Air lead level test:By atomic absorption spectrometry method based on GBZ/T160.10-2004.2.3 The ELISA reagent kit was used to detect the plasma levels of HSP70.The operation was strictly executed according to the direction.2.4 Blood lead level test:By atomic absorption spectrometry method based on WS/T 174-1999. 2.5 Urine lead level test:By derivative potential stripping method based on WS/T 19-1996.2.6 Super oxide dimutase(SOD) assaying:By xanthine oxidase method.The operation was strictly executed according to the direction.2.7 Glutathione peroxidase(GSH-Px) assaying:By 5,5’-Dithiobis(2-nitrobenzoic acid) method.The operation was strictly executed according to the direction.2.8 Catalase(CAT) assaying:By ammonium molybdate method.The operation was strictly executed according to the direction.2.9 Malondialdehyde(MDA) assaying:By thio-barbituric acid method.The operation was strictly executed according to the direction.2.10 The statistical analysis was performed using SPSS 10.0 software.The test level was equal to 0.05.Results1 Lead content in the workplace air showed the range of short term exposure limit concentration(STEL) was from 0.101mg/m~3 to 1.380mg/m~3,and the range of time weighted average concentration(TWA) was from 0.045mg/m~3 to 0.738mg/m~3.2 Compared with control group,HSP70 protein experssion showed significant a increase 6 fold using ELISA assay(P<0.05).3 Contents of blood and urine lead in exposed group was significantly higher than that in control group(P<0.05).4 Contents of GSH-Px and CAT in plasma in exposed group showed much lower than that in control group(P<0.05).Compared with control group,content of MDA in plasma showed much higher than in exposed group(P<0.05).5 Correlation test showed that HSP70 level in exposed and nonexposed group is closely correlated with content of blood lead,coefficient of correlation: r=0.322,(P<0.05).Correlation test showed that HSP70 level in exposed and nonexposed group is closely correlated with content of urine lead,coefficient of correlation:r=0.319,(P<0.05).Correlation test showed that blood lead in exposed and nonexposed group is closely correlated with content of urine lead,coefficient of correlation:r=0.883,(P<0.05).Conclusion1 The levels of lead exposure closedty correlated with oxidative injury in smelting workers.Lead can induce the lipid peroxidation in exposed workers and decrease the antioxidative ability.2 HSP70 may be a sensitive biomaker of occupational lead exposure.更多还原