应用程序控制行为测试研究甲基汞和微波对仔鼠神经行为的影响

[目的]应用程序控制行为测试分别评价妊娠期暴露于氯化甲基汞、频率1800MHz低强度微波辐射对F1 代大鼠的神经行为毒性。[方法]Wistar大鼠以雌雄2∶1合笼交配 ,受孕母鼠随机分组。实验1:于孕鼠妊娠第6～9d给予氯化甲基汞 ,0、0.01、0.05、2.00mg/(kg·day)连续灌胃染毒。随机选择32只F1 代大鼠 (雌雄各半 )于10周龄时进行程序控制行为测试。实验2:于孕鼠妊娠第1～20d暴露于频率为1800MHz,功率密度为0.5、1.0mW/cm2 的微波辐射 ,对照组为虚拟暴露 ;随机选择48只F1 代大鼠 (雌雄各半 )于10周龄时进行程序控制行为测试。[结果]实验1:甲基汞3个剂量组大鼠的学习成绩在两种程序均比对照组降低 (P<0.05或P<0.01) ,存在剂量_反应关系 (高频度差别强化率rs= -0.7273 ,P<0.01;低频度差别强化率rs= -0.2238,P>0.05)。实验2:1800MHz、功率0.5mW/cm2 微波组雄性仔鼠在高频度差别强化率 (DRH8/4)的成绩比对照组降低 (P<0.05)。[结论]胚胎期暴露于低剂量甲基汞对大鼠可产生神经行为毒性 ,表现为学习记忆功能异常 ;出生前暴露于频率1800MHz微波对仔鼠神经行为发育的影响尚不能确定。     

两种神经行为毒理学方法在甲基汞毒性测定中的比较

为了比较行为毒理学研究中常用的迷宫和操作行为两种测试方法 ,将Wistar孕鼠随机分为 4组 ,于妊娠第 6～ 9天采用甲基汞 0 0 0、0 0 1、0 0 5、2 0 0mg (kg·d)连续灌胃染毒。随机抽取 4个实验组仔鼠共79只于 7周龄时进行Y型迷宫负性强化法测试 ;32只于 10周龄时进行自动化操作行为正性强化法测试。整个实验采用双盲法。结果表明 ,仔鼠学习成绩在两种测试中均无性别差异。迷宫测试显示 3个剂量组错误次数均显著高于对照组 (P <0 0 5 ) ,具有剂量 反应关系 (rs=0 2 5 7,P <0 0 5 ) ;到达安全区平均时间比对照组时间延长 (P <0 0 5 ) ,具有剂量 反应关系 (rs=0 2 16 ,P <0 0 1)。操作行为测试显示 3个剂量组仔鼠的学习成绩均比对照组降低 (P <0 0 5 ) ,存在剂量 反应关系 (高频度差别强化程序rs=- 0 72 73,P <0 0 1;低频度差别强化程序rs=- 0 2 2 38,P >0 0 5 )。表明迷宫和操作行为测试均可检出大鼠胚胎期低剂量甲基汞暴露的神经行为学效应。由于迷宫测试采用人工记录和负性强化 ,受干扰因素较多 ;而采用电脑控制正性强化的操作行为测试 ,具有不损伤动物、客观、敏感、安全、可定量等优点     

甲基汞急性暴露大鼠脑中汞蓄积及胆碱能神经递质改变的研究

目的 研究低剂量甲基汞短期暴露的神经毒性作用,为进一步探讨甲基汞早期神经毒性机制提供实验依据。方法 采用SD大鼠腹腔注射甲基汞,剂量分别为0．05、0．50及5．00mg／kg,并设对照组,分别暴露20min、1、4、24h时测定大鼠脑组织总汞含量、乙酰胆碱(ACh)含量及乙酰胆碱酯酶(AChE)活力。结果 除0．05mg／kg剂量组外,其余两组大鼠脑组织中汞含量在暴露20min就显著升高;0．05mg/kg组大鼠暴露4h后,脑汞含量也出现显著升高。各剂量组大鼠脑组织ACh及AChE都在暴露20min后就出现显著变化,并显示一定的剂量——效应和时间——效应关系。结论 甲基汞低剂量(0．05mg／kg)短时间暴露(20min)时脑组织ACh和AChE的改变表明此时可能启动了中枢神经系统某种调控机制。随暴露剂量和暴露时间增加,甲基汞蓄积于大鼠脑组织中,可引起脑组织ACh含量和AChE活力显著变化。     

胚胎期暴露于甲基汞大鼠的迷宫测试

为研究胚胎期甲基汞暴露对大鼠迷宫学习与记忆能力的影响 ,用不同剂量甲基汞 [0、0 .0 1、0 .0 5和 2 .0 0 mg/ (kg· d) ]于大鼠孕 6～ 9天连续灌胃染毒 ,仔鼠出生 7周时进行 Y型迷宫测试。学习记忆成绩以平均错误次数、到达安全区平均时间和主动回避率表示。整个实验采用双盲法。结果与对照组相比 ,各暴露组大鼠的平均错误次数和到达安全区平均时间显著增高 ,主动回避率显著降低 (P<0 .0 5或 P<0 .0 1) ;各组大鼠学习记忆能力无性别差异。提示甲基汞可通过胎盘屏障和乳汁进入仔鼠体内 ,影响仔鼠神经系统的发育 ,使其学习记忆能力受到明显损害     

高温与低剂量香烟联合致仔鼠神经行为异常研究

目的 探讨高温与香烟联合对卫鼠神经行为发育的影响。方法 孕10天的大鼠暴露于高温（41℃和42℃），同时在孕2，4，6，8，10，12，14天时注射低剂量的香烟烟雾水溶物（1．0支／只），观察分析仔鼠体格发育、反射行为及学习记忆等神经行为。结果 高温组（4℃和42℃）仔鼠体格发育（开眼、张耳、生毛、出牙）和反射感觉功能（平面翻正、空中翻正、视觉定向和听觉惊愕）的达标天数及学习与记忆能力达标时间（分）与对照组及37℃组比较延忱（P＜0．01）；现时还表明持续较长时间的高温（＞1．5分钟）与香烟联合对仔鼠上棕神经行为具有复合作用，与单独高温组比较有显性差异（P＜0．01）。结论 持续较长时间的高温与香烟联合可仔鼠生长发育延缓及学习记忆功能降低等神经行为异常。     

氯化甲基汞染毒对大鼠后代发育的影响

目的探讨甲基汞对雄性大鼠生殖功能的影响和通过父系传播对后代的影响。方法将20只Wistar雄性大鼠随机分为4组,分别给予0、0．058、0．580、1．170mg／kg体重的氯化甲基汞,以隔日经口灌胃的方式染毒,持续染毒2个月后,将其与健康雌性大鼠交配,观察仔鼠的生长发育与神经行为发育情况。结果1．170、0．580mg／kg组仔鼠体重低于对照组,其早期生长发育指标落后于对照组仔鼠;染毒组仔鼠转体时间延长、前肢悬挂时间缩短,与对照组相比,差异有统计学意义（P〈0．05）。观察组仔鼠平面翻正、断崖回避、空中翻正的正确率与对照组相比,也明显降低（P〈0．01或P〈0．05）。结论雄鼠甲基汞染毒后,可以影响仔鼠的生长发育和神经行为发育。     

染铅对大鼠脾脏NOS、NO、SOD、MDA的影响

目的 探讨染铅对大鼠脾脏一氧化氮合酶（NOS）活力、一氧化氮（NO）含量的影响及其与血铅相互关系。方法 Wistar大鼠经饮水（加0，18．4，184．0mg/L醋酸铅，分别供对照组、低剂量组、高剂量组自由饮用）染毒，测定脾脏NOS活力、NO含量、SOD活力、MDA含量。结果 NOS活力高剂量染铅组7d时显著低于对照组和低剂量组（P＜0．05），90d高于对照组和低剂量组（P＜0．05），低剂量组90d高于对照组（P＜0．05）；NO含量高剂量组和低剂量组60d、90d时均显著低于对照组（P＜0．05）；SOD活力高剂量组14d、30d、60d、90d时均低于对照组（P＜0．05），低剂量组30d、90d时显著低于对照组（P＜0．05）；MDA含量高剂量组14d、60d、90d时均显著高于对照组，60d时显著低于低剂量组，90d时显著高于低剂量组（P＜0．05），低剂量组在各时点与对照组比较，差异无显著性（P＞0．05）。血铅与脾脏NO含量呈倒S型剂量－效应曲线；血铅与脾脏SOD活力呈倒抛物线型剂量－效应曲线；血铅与脾脏MDA含量呈正抛物线型剂量－效应曲线。结论 铅可引起大鼠脾脏NOS活力、NO含量、SOD活力、MDA含量改变，表明铅可引起体内氧应激反应导致脂质过氧化损伤。     

甲基汞暴露对出生后大鼠学习记忆及NMDA受体表达的影响

[目的]研究甲基汞暴露对出生后不同生长期大鼠学习记忆能力及N-甲基0．天冬氨酸（NMDA）受体mRNA水平表达的影响。[方法]将出生后大鼠随机分组,即5mL／kg生理盐水组和5mg／kg氯化甲基汞（MMC）染毒组,其中染毒组按生后不同生长时期分4个亚组,即PND7、PND14、PND28和PND60组,连续7d灌胃染毒。采用Morris水迷宫试验检测大鼠学习记忆功能的改变,用原子荧光光度计检测脑组织汞含量、用逆转录一聚合酶链式反应（RT-PCR）特异性扩增受体NMDA的2A、2B、2C亚基,半定量分析PCR产物凝胶电泳结果。[结果]各染毒亚组在染毒后脑组织中汞含量明显高于对照组（P〈0．01）,水迷宫试验后,PND28皮质组织及PND60脑组织中汞含量明显高于对照组（P〈0．01）;Morris水迷宫试验结果显示,PND7、PND14染毒大鼠水迷宫测试潜伏期明显长于对照组（P〈0．01）;PND14染毒亚组海马和皮质中NR2AmRNA的表达明显低于对照组（P〈0．05）;PND14染毒亚组海马中NR2BmRNA表达明显低于对照组（P〈0．01）;PND14染毒亚组海马和皮质以及PND28亚组皮质中NR2CmRNA表达明显高于对照组（P〈0．01）.[结论]甲基汞对出生后1、2周的大鼠学习记忆功能有明显影响,其影响与脑组织NMDA受体2亚基mRNA表达变化有关。     

低浓度苯暴露对大鼠神经行为的影响

摘要:目的　研究低浓度气态苯吸入对大鼠学习记忆等神经行为的影响,并探讨低浓度苯吸入对大鼠血象的改变。方法　SD雄性大鼠随机分4组,每组10只,低、中、高剂量组苯染毒浓度分别为4 mg/m3、6 mg/m3和10 mg/m3,对照组吸入空气。采用静式吸入染毒法,4 h/d,5 d/w,持续染毒4 w,染毒结束后进行学习记忆等神经行为学测试、血象、嗜多染红细胞微核实验。结果　Morris水迷宫定位航行实验,高剂量组大鼠d 3、d 4的逃避潜伏期明显高于对照组（P＜0.05）,空间探索实验的目标象限时间明显低于对照组（P＜0.05）。高剂量组大鼠的后肢撑力指数明显高于对照组（P＜0.05）。低、中、高剂量组白细胞计数明显低于对照组（P＜0.05）。结论　低剂量、短时间暴露苯可损害大鼠学习记忆及运动功能,引起外周血白细胞计数降低。     

母鼠低剂量甲基汞染毒致亲、仔代肝脏的氧化损伤

[目的]ICR母鼠通过饮水染毒低剂量氯化甲基汞（MeHgCl），观察MeHgCl对子代生长发育以及亲、仔代氧化损伤的影响。[方法]ICR孕鼠随机分为对照组、低剂量组和高剂量组，各组于怀孕第6天起分别自由饮用蒸馏水和MeHgCl含量分别为0．01、0．1mg／L（相当于饮用水汞含量标准的8倍和80倍剂量）的蒸馏水直至哺乳期结束。研究指标包括母鼠孕期和仔鼠出生后的体重增长及母鼠、仔鼠肝脏中汞含量、脂质过氧化产物丙二醛（MDA）含量及总抗氧化活力（T-AOC）的水平。[结果]在0．01和0．1mg／L剂量下，亲仔两代体重增长各剂量组无差异，也未出现明显的毒性反应，但均有明显的体内汞蓄积。表现为对照组、低剂量组和高剂量组母鼠肝脏汞含量分别为3．703、11．516、100．821ng／g组织湿重，仔鼠肝脏汞含量分别为2．664、5．454、38．846ng／g组织湿重。对照组、低剂量组和高剂量组母鼠总抗氧化活力和MDA含量分别为2．833、2．517、1．974U／mg蛋白和0．849、1．883、2．219nmol／mg蛋白，与对照组相比，甲基汞可使母鼠肝脏总抗氧化活力降低，肝脏中MDA含量增加（P〈0．05）；对照组、低剂量组和高剂量组仔鼠总抗氧化活力和MDA含量分别为1．860、2．361、2．945U／mg蛋白和0．506、0．702、0．617nmol／mg蛋白，甲基汞使仔鼠总抗氧化活力升高（P〈0．05），使低剂量组MDA含量明显高于对照组（P〈0．05），但MDA含量高剂量组和对照组相比变化不显著（P〉0．05）。[结论]在相当于饮用水汞卫生标准8倍和80倍剂量水平上，低剂量甲基汞虽未引起仔代明显发育障碍，但是可通过母体在仔代体内蓄积，并对亲、仔代肝脏产生不同的氧化损伤。     

Self-reported health problems among Swedish miners one year after unemployment

Unemployment is considered to be a public health concern sincedeterioration in the health of the unemployed is often anticipated.However, for some groups, such as miners, unemployment mightimprove health due to a cessation of potentially harmful occupationalexposures. This study evaluates the health of 79 miners in oneSwedish iron-ore mine, and 226 age-matched controls from thegeneral population, during one year after the closure of themine. The participants received a questionnaire regarding medicalhistory and subjective symptoms at the beginning of the studyperiod, and after one year. Statistically significant negativeeffects on self-reported health attributable to unemploymentwere not found, although neuropsychiatric symptoms were morecommon among the unemployed miners. The miners reported a statisticallysignificant improvement in grip force (p=0.031). They had asignificantly higher prevalence of symptoms associated withmining related exposures when compared with the population controls;pain in the upper extremities [relative risk (RR)=2.27, 95%confidence interval (Cl)=1.44–3.59), back pain (RR=1.84;Cl=1.237–2.75), vasospastic disease of the fingers (RR=2.05;Cl=1.18–3.57) and obstructive respiratory symptoms (attacksof dyspnea and wheezing: RR=3.67; Cl=1.167–11.6).     

Excès de cas humains et animaux de tularémie en France au cours de l’hiver 2007–2008 : émergence ou phénomène isolé ?

Context

Tularemia is a zoonosis affecting humans and hares in France. We describe the results of surveillance in both species, in 2007 and 2008.

Methods

Human tularemia cases are mandatorily notifiable in France since 2003. In hares, surveillance relies on volunteer hunter associations in all districts of the country. Data from mandatory reports and volunteer surveillance in 2007/2008 were analyzed and compared with previous results.

Results

In 2007/2008, 144 cases were reported in humans and 117 cases in hares. This was a 100% increase compared to previous years. Human cases differed from those of previous years only by the frequency of contact with breeding animals. Human cases without any documented risk exposure were also more frequent.

Conclusion

An increase of tularemia cases occurred in 2007/2008 in both species. Complementary studies are needed to identify the species reservoir in France to understand the causes of this peak of cases.     

Occupational health hazards in mining: an overview

This review article outlines the physical, chemical, biological, ergonomic and psychosocial occupational health hazards of mining and associated metallurgical processes. Mining remains an important industrial sector in many parts of the world and although substantial progress has been made in the control of occupational health hazards, there remains room for further risk reduction. This applies particularly to traumatic injury hazards, ergonomic hazards and noise. Vigilance is also required to ensure exposures to coal dust and crystalline silica remain effectively controlled.     

Manufacture and use of nanomaterials: current status in the UK and global trends

This paper provides an overview of the production and use of nanomaterials (NMs), particularly in the UK. Currently, relatively few companies in the UK are identifiable as NM manufacturers, the main emphasis being the bulk markets in metals and metal oxides, and some niche markets such as carbon nanotubes and quantum dots. NM manufacturing in the UK does not reflect the global emphasis on fullerenes, nanotubes and fibres. Some assumptions have been made about the types of NM that are likely to be imported into the UK, which currently include fullerenes, modified fullerenes and other carbon-based NMs including nanotubes. Many university departments, spin-offs and private companies have developed processes for the manufacture of NMs but may only be producing small quantities for research and development (R&D) purposes. However, some have the potential to scale up to produce large quantities. The nanotechnology industry in the UK has strong R&D backup from universities and related institutions. This review has covered R&D trends at such institutions, and appropriate information has been added to a searchable database. While several companies are including NMs in their products, only a few (e.g. manufacturers of paints, coatings, cosmetics, catalysts, polymer composites) are using nanoparticles (NPs) in any significant quantities. However, this situation is likely to change rapidly. There is a need to collect more information about exposure to NPs in both manufacturing and user scenarios. As the market grows, and as manufacturers switch from the micro- to the nanoscale, the potential for exposure will increase. More research is required to quantify any risks to workers and consumers.     

Investigating clusters in the workplace and beyond

Clusters of disease are common and occur in the workplace and in the general community. They often arouse considerable concern among the population. Investigations have sometimes lead to exciting new knowledge, but in general the investigation of clusters is difficult and often unrewarding, especially for community clusters. In the workplace, investigations are more likely to find associations and even new causes, but still many clusters remain enigmatic. Despite this, there are many reasons for investigating clusters, including allaying community concern and identifying uncontrolled exposures. A structure for investigating clusters in the workplace is suggested.     

Assessing occupational and environmental exposure

Exposure assessment is a poorly understood component of the science of epidemiology. The relationship between exposure to chemicals and ill-health outcomes is often calculated using crude exposure measures such as ever/never exposed or duration. When investigating subtle effects, exposures need to be characterized much more fully in terms of intensity, frequency, duration and route. While occupational exposures tend to be much greater than those experienced from the wider environment there is a need to remember that, for many chemicals, exposure can occur occupationally, environmentally and through consumer use of products containing the material of interest. Inhalation exposure has generally been the traditional focus for most epidemiological investigations but there is now growing awareness of the importance of the dermal and ingested routes of contact and internalization. Quantification of the exposure also needs to be related to a biological mechanism of action and exposure metrics need to be selected accordingly. Occupational exposures can generally be measured using simple well-validated techniques. Environmental exposures require much more sensitive instruments and are more difficult to assess. Exposure modelling, particularly for the environmental fate of chemicals has undergone many recent developments and Monte Carlo techniques can be used to characterize model uncertainty and variability. This approach to exposure assessment can now be used in the setting of the wider environment and will enable a far better understanding of the relationship between exposure and disease.     

Mercury toxicity due to the smelting of placer gold recovered by mercury amalgam

A 19-year-old man developed tremor in both hands and fatigue after starting work at a placer gold mine where he was exposed to mercury-gold amalgam. Examination revealed an intention tremor, dysdiadochokinesis and mild rigidity. The 24-h urinary mercury concentration reached a peak of 715 nmol/l (143 ug/l) shortly before the clinical examination, after which he was removed from working in the gold room [Mercury No. Adverse Effect Level: 250 nmol/l (50 ug/l)]. On review 7 weeks later his tremor had almost resolved and the dysdiadochokinesis and rigidity had gone. The 24-h urinary mercury concentration had fallen to 160 nmol/l (32 ug/l). The principal exposure to mercury was considered to be the smelting of retorted gold with previously unrecognized residual mercury in it. The peak air concentration of mercury vapour during gold smelting was 0.533 mg/m3 (Mercury Vapour ACGIH TLV: 0.05 mg/m3 TWA). Several engineering and procedural controls were instituted. This episode occurred at another mine site, unrelated to Mount Isa Mines Limited.     

How Adults with Acquired Brain Damage Perceive Computer Training as a Rehabilitation Tool: A Focus-group Study

The aim of this study was to explore and describe how adult outpatients with acquired brain damage and referred to occupational therapy perceive computer training with the RehaCom programs, in order to evaluate the method of treatment as a tool in the rehabilitation of persons with cognitive disorders. By using focus-group discussions as a qualitative method of research when analysing the result, five themes with corresponding categories emerged, describing a development of understanding and learning about capacities. Themes describing how the participants could apply strategies to overcome shortcomings in daily occupations and the therapeutic role of the occupational therapist were identified as well. The result shows that a computer training program such as RehaCom can be used as an educational tool, for example, to guide a person who is trying to adopt compensatory strategies to avoid overload by taking pauses. It was found that anything the participants learned was also applicable to occupational performance in daily life.