亚砷酸钠对人正常肝细胞凋亡及Bax和Bcl-2 mRNA和蛋白表达的影响

目的探讨亚砷酸钠对人正常肝(L-02)细胞凋亡及Bax、Bcl-2 m RNA和蛋白表达的影响。方法将L-02肝细胞分别暴露于含0(对照)、50、100、150μmol/L亚砷酸钠的培养基中暴露24 h。采用MTT法检测L-02肝细胞的存活率,采用流式细胞术检测L-02肝细胞凋亡率,采用RT-PCR的方法检测Bax、Bcl-2 m RNA相对表达情况,采用Westernblotting方法检测L-02肝细胞中Bax、Bcl-2蛋白的表达情况。结果与对照组相比,各浓度亚砷酸钠染毒组L-02细胞的存活率均较低,凋亡率均较高,差异均有统计学意义(P0.05);且随着亚砷酸钠染毒浓度的升高,L-02细胞的存活率呈下降趋势,而凋亡率上升趋势。与对照组相比,各浓度亚砷酸钠染毒组L-02细胞中Bcl-2、Bax m RNA和蛋白的表达水平均较高,100μmol/L亚砷酸钠染毒组Bcl-2 m RNA/Bax m RNA值也较高,而150μmol/L亚砷酸钠染毒组Bcl-2 m RNA/Bax m RNA值及50、150μmol/L亚砷酸钠染毒组Bcl-2蛋白/Bax蛋白值均较低,差异均有统计学意义(P0.05)。结论亚砷酸钠可抑制L-02肝细胞的生长,诱导细胞凋亡的发生;其机制可能与Bcl-2家族的激活有关。     

氧化应激在全氟辛烷磺酰基化合物诱导人胚胎肝细胞凋亡中的作用

目的探讨全氟辛烷磺酰基化合物(PFOS)致人胚胎肝(L-02)细胞凋亡的作用及其机制。方法将处于对数生长期的L-02细胞分别暴露于终浓度为0(对照)、50、100、150、200μmol/L的PFOS溶液培养24 h。采用MTT法检测细胞活性,采用流式细胞术检测细胞凋亡率,并测定细胞线粒体内活性氧(ROS)、谷胱甘肽(GSH)、丙二醛(MDA)和超氧化物歧化酶(SOD)的水平及线粒体膜电位,采用q RT-PCR法检测凋亡相关基因caspase-3、caspase-9、bax、bcl-2 m RNA的表达水平。结果与对照组比较,150、200μmol/L PFOS染毒L-02细胞的存活率均降低,而100、150、200μmol/L PFOS染毒组L-02细胞的凋亡率均增加,差异均有统计学意义(P0.05);且随着PFOS染毒浓度的升高,L-02细胞的存活率呈下降趋势,而凋亡率呈上升趋势。与对照组比较,各浓度PFOS染毒组L-02细胞内ROS和MDA水平均增加,而各浓度PFOS染毒组L-02细胞内SOD水平和100、150、200μmol/L PFOS染毒组L-02细胞内GSH水平和线粒体膜电位均较低,差异均有统计学意义(P0.05);且随着PFOS染毒浓度的升高,L-02细胞内ROS和MDA水平均呈上升趋势,而SOD、GSH水平和线粒体膜电位均呈下降趋势。与对照组比较,各浓度PFOS染毒组L-02细胞中caspase-3、caspase-9、Bax m RNA的表达水平均较高,而bcl-2、bcl-2/bax值均较低,除50μmol/L PFOS染毒组caspase-9外,差异均有统计学意义(P0.05﹚。结论在本实验剂量下,PFOS暴露可引起L-02细胞凋亡,其机制与PFOS诱导的氧化损伤和线粒体凋亡途径有关。     

c-Jun氨基末端激酶在镉致小鼠脑原代星形胶质细胞凋亡中的作用

目的利用原代培养的小鼠脑星形胶质细胞(astrocytes,AS),探讨c-Jun氨基末端激酶(JNK)信号转导通路是否参与镉致小鼠脑星形胶质细胞凋亡的过程。方法原代培养的小鼠脑星形胶质细胞给予0~20μmol/L镉染毒0~24 h,倒置相差显微镜观察细胞形态变化;给予0~20μmol/L镉染毒9、12 h,采用MTT法检测细胞存活率;给予0~20μmol/L镉染毒12 h,采用Annexin V-FITC/PI双染流式细胞术检测细胞凋亡率;给予0~20μmol/L镉染毒0~12 h,采用蛋白印迹(Western blotting)法检测JNK磷酸化蛋白的表达水平。结果镉浓度为5~20μmol/L时,随染毒剂量的升高及作用时间的延长,细胞形态发生明显改变:细胞间网络连接松散,突起消失,胞体收缩成球形,贴壁能力下降,最终脱落,漂浮于培养液中。与对照组比较,各浓度镉染毒9、12 h后小鼠脑星形胶质细胞的存活率均下降,差异有统计学意义(P0.01);且随着镉染毒浓度的升高和染毒时间的延长,小鼠脑星形胶质细胞的存活率均呈下降趋势。与对照组比较,各浓度镉染毒12 h后小鼠脑星形胶质细胞的凋亡率均升高,差异有统计学意义(P0.01);且随着镉染毒浓度的升高,小鼠脑星形胶质细胞的凋亡率均呈上升趋势。与对照组比较,5~20μmol/L镉染毒3 h后小鼠脑星形胶质细胞内p-JNK表达量均升高,20μmol/L镉染毒6 h后小鼠脑星形胶质细胞内p-JNK表达量升高,10~20μmol/L镉染毒9、12 h后小鼠脑星形胶质细胞内p-JNK表达量均升高,差异有统计学意义(P0.05);与0 h比较,0~20μmol/L镉染毒3~12 h后小鼠脑星形胶质细胞内p-JNK表达量均升高,差异有统计学意义(P0.05);且随着镉浓度的升高和染毒时间的延长,小鼠脑星形胶质细胞内p-JNK的表达量均呈上升趋势。结论镉可能通过上调JNK磷酸化蛋白的表达水平来诱导小鼠脑星形胶质细胞的凋亡。     

竹荪多糖对亚砷酸钠致人肝细胞毒性的拮抗作用

目的探讨竹荪多糖对亚砷酸钠致人胎肝(L-02)细胞毒性的拮抗作用。方法将处于对数生长期的L-02细胞分别暴露于含不同浓度[0(对照)~80μmol/L]亚砷酸钠和[0(对照)~160μg/ml]竹荪多糖+10μmol/L亚砷酸钠的培养液中暴露24 h,采用四甲基偶氮唑蓝(MTT)法测定细胞存活率。将处于对数生长期的L-02细胞分设对照(培养基)组、亚砷酸钠(10μmol/L)组、竹荪多糖(80μg/ml)组和联合处理(10μmol/L亚砷酸钠+80μg/ml竹荪多糖)组,暴露24 h后,检测细胞培养液中丙二醛(MDA)、总超氧化物歧化酶(T-SOD)、过氧化氢酶(CAT)、还原性谷胱甘肽(GSH)、细胞色素C(Cyt-C)水平和天冬氨酸蛋白水解酶3(Caspase-3)的活力及B淋巴细胞瘤-2(Bcl-2)蛋白、Bcl-2相关X(Bax)蛋白的表达水平。结果与对照组比较,除2.5和5μmol/L亚砷酸钠染毒组外,10~80μmol/L亚砷酸钠染毒组L-02细胞的存活率均下降,差异有统计学意义(P0.05);且随着亚砷酸钠染毒剂量的升高,L-02细胞的存活率呈下降趋势。与对照组比较,40、80和160μg/ml竹荪多糖联合处理组L-02细胞的存活率均升高,差异有统计学意义(P0.05);其中,以80μg/ml竹荪多糖的拮抗效果最好。与对照组比较,亚砷酸钠组和联合处理组L-02细胞培养液中MDA和Cyt-C的水平升高,T-SOD、CAT及GSH的水平降低,差异均有统计学意义(P0.05);而竹荪多糖组L-02细胞培养液中上述指标均无明显变化。与亚砷酸钠组比较,联合处理组和竹荪多糖组L-02细胞培养液中MDA和Cyt-C的水平降低,T-SOD、CAT及GSH的水平升高,差异均有统计学意义(P0.05)。与对照组比较,亚砷酸钠组和联合处理组L-02细胞胞内Caspase-3的活力升高,差异具有统计学意义(P0.05);而竹荪多糖组L-02细胞细胞内Caspase-3的活力无明显变化。与亚砷酸钠组比较,联合处理组和竹荪多糖组L-02细胞内Caspase-3的活力均降低,差异有统计学意义(P0.05)。与对照组比较,亚砷酸钠组和联合处理组L-02细胞胞内Bcl-2、Bax蛋白的表达水平升高,Bcl-2/Bax比值降低,差异均有统计学意义(P0.05);而竹荪多糖组L-02细胞上述指标均无明显变化。与亚砷酸钠组比较,联合处理组和竹荪多糖组L-02细胞胞内Bax蛋白的表达水平降低,Bcl-2/Bax比值升高;竹荪多糖组L-02细胞内Bcl-2蛋白的表达水平降低,差异均有统计学意义(P0.05)。结论亚砷酸钠可以诱导L-02细胞氧化应激,通过激活线粒体途径的细胞凋亡发挥毒性作用;竹荪多糖可以通过抑制上述机制,拮抗亚砷酸钠所致L-02细胞的毒性作用。     

JNK信号通路在NaAsO2诱导L-02肝细胞 凋亡过程中的作用

摘要:目的　研究JNK在NaAsO2诱导L-02肝细胞凋亡中的作用。方法　用不同浓度NaAsO2染毒L-02肝细胞,采用流式细胞术检测L-02肝细胞凋亡率;Western-blot检测L-02肝细胞中Jnk、p-Jnk、Caspase-3蛋白的相对表达量。结果　0、50、100 和 150 μmol/L组细胞凋亡率分别为3.33%±0.30%、7.49%±0.23%、9.48%±0.49%和 14.87%±2.17%,染毒组的细胞凋亡率随NaAsO2浓度的增加而升高,差异有统计学意义（P＜0.05）;染毒组细胞内Jnk、p-Jnk、Caspase-3蛋白相对表达量均增高,差异有统计学意义（P＜0.05）。结论　NaAsO2能诱导L-02肝细胞凋亡的发生,这可能与激活JNK,增加JNK磷酸化水平,继而激活凋亡调控基因Caspase-3有关。     

氧化苦参碱对亚砷酸钠致人肝细胞损伤的拮抗作用

目的探讨氧化苦参碱(oxymatrine,OM)对亚砷酸钠致人胎肝(L-02)细胞株损伤的拮抗作用。方法将处于对数生长期的L-02细胞分别培养于0μmol/L亚砷酸钠(对照)、OM(200μg/ml)、亚砷酸钠(100μmol/L)及亚砷酸钠(100μmol/L)+OM(50、100、200μg/ml)的培养基中暴露18 h。检测细胞培养液中天冬氨酸氨基转移酶(AST)、丙氨酸氨基转移酶(ALT)的水平和细胞葡萄糖调节蛋白78(glucose regulated protein 78,GRP78)、CCAAT/增强子结合蛋白同源蛋白(CCAAT/enhancer-binding protein homologous protein,CHOP)蛋白的表达水平及细胞凋亡率。结果OM组与对照组各项指标差异均无统计学意义(P0.05)。与对照组及OM处理组比较,亚砷酸钠组细胞培养上清液中AST、ALT水平、细胞凋亡率、GRP78及CHOP蛋白表达水平显著升高(P0.05);而不同浓度OM干预后,上述指标均有不同程度下降(P0.05)。且随着OM干预浓度的升高,上述指标均呈下降趋势。结论砷可致L-02细胞损伤,OM可通过抑制L-02细胞内质网应激及减少肝细胞凋亡,从而发挥对肝细胞的保护作用。     

亚砷酸钠对Chang肝细胞增殖与凋亡的影响

目的 探讨亚砷酸钠对正常人Chang肝细胞体外增殖及凋亡的影响.方法 采用0(对照)～100 μmol/L亚砷酸钠分别处理细胞24、48、72、96 h.采用MTT比色法检测细胞活力;采用流式细胞术检测染毒48 h时的细胞凋亡率.结果 仅0.2μmol/L亚砷酸钠染毒24 h的细胞活力略高于对照组,但差异无统计学意义;且随着亚砷酸钠染毒浓度的升高和染毒时间的延长,Chang肝细胞存活率均呈下降趋势,并具有剂量-效应和时间-效应关系.与对照组相比较,5～100 μmol/L亚砷酸钠染毒组Chang肝细胞凋亡率均显著升高,差异有统计学意义(P＜0.05);且随着亚砷酸钠染毒浓度的升高,Chang肝细胞的凋亡率呈显著升高趋势,并具有剂量-效应关系.结论 亚砷酸钠有明显的细胞毒性,能抑制Chang肝细胞的增殖,这可能与其诱导细胞凋亡有关.     

砷对人永生化角质形成细胞核转录因子红细胞系-2p45相关因子-2和Kelch样环氧氯丙烷相关蛋白-1基因表达的影响

目的探讨不同剂量亚砷酸钠对人永生化角质形成细胞(human keratinocytes cell,Ha Ca T)Kelch样环氧氯丙烷相关蛋白-1(Keap1)和核转录因了红细胞系-2 p45相关因子-2(Nrf2)基因表达的影响。方法将Ha Ca T细胞分别暴露于终浓度为0(对照)、1.30、3.25、6.50μmol/L的亚砷酸钠培养基中培养24、48、72 h。采用流式细胞仪检测Ha Ca T细胞凋亡率,采用实时荧光定量(real-time quantitative PCR)检测Ha Ca T细胞中Nrf2、Keap1 m RNA的表达水平。结果与对照组相比,1.30μmol/L亚砷酸钠染毒24 h后Ha Ca T细胞的凋亡率降低,而3.25、6.50μmol/L亚砷酸钠染毒48、72 h后Ha Ca T细胞的凋亡率升高,差异均有统计学意义(P0.05);且随着亚砷酸钠染毒时间的延长和染毒剂量的升高,Ha Ca T细胞的凋亡率均呈上升趋势。与对照组相比,1.30μmol/L亚砷酸钠染毒24、48、72 h和3.25μmol/L亚砷酸钠染毒24 h后Ha Ca T细胞中Nrf2 m RNA的表达水平均增高,而3.25、6.50μmol/L亚砷酸钠染毒72 h后Ha Ca T细胞中Nrf2 m RNA的表达水平均下降,差异有统计学意义(P0.05);且随着亚砷酸钠染毒时间的延长和染毒剂量的升高,Ha Ca T细胞Nrf2 m RNA的表达水平均呈下降趋势。与对照组相比,1.30、3.25μmol/L亚砷酸钠染毒72 h和3.25、6.50μmol/L亚砷酸钠染毒48 h后Ha Ca T细胞中Keap1 m RNA的表达水平均增高,差异有统计学意义(P0.05)。随着亚砷酸钠染毒时间的延长,1.30μmol/L亚砷酸钠染毒组Ha Ca T细胞中Keap1 m RNA的表达水平呈波动性上升,3.25μmol/L亚砷酸钠染毒组Ha Ca T细胞中Keap1 m RNA的表达水平呈逐渐上升趋势,6.50μmol/L亚砷酸钠染毒组Ha Ca T细胞中Keap1 m RNA的表达水平呈先上升后下降;随着亚砷酸钠染毒剂量的升高,24、72 h时Ha Ca T细胞中Keap1 m RNA的表达水平呈下降趋势,而48 h时Ha Ca T细胞中Keap1 m RNA的表达水平呈上升趋势。结论亚砷酸钠可抑制Ha Ca T细胞的生长,诱导凋亡和角化的发生,其机制可能与Nrf2和Keap1基因的表达有关。     

镉与汞联合作用对人胚肝细胞凋亡和DNA损伤的影响

目的 研究镉与汞单独及联合染毒对人胚肝细胞(L02细胞)凋亡及DNA损伤的作用.方法 以0.01～100μmol/L的氯化镉、氯化汞以及等浓度的氯化镉、氯化汞混合液对L02细胞染毒24 h,采用MTT法测定细胞的存活率,根据Finney法判断镉与汞对L02细胞的联合作用类型;采用单细胞凝胶电泳技术(SCGE)和流式细胞术(FCM)检测L02细胞的DNA损伤和细胞凋亡情况.结果 0.01 μmol/L的氯化镉、氯化汞单独及联合染毒可以刺激细胞的生长,但≥1μmol/L的氯化镉、氯化汞单独及联合染毒可显著抑制细胞的生长;且联合作用表现为相加作用.镉、汞单独及联合作用可致L02细胞的DNA损伤率和细胞凋亡率均显著高于对照组;且随着染毒浓度的升高,L02细胞的DNA损伤率和细胞凋亡率均呈上升趋势.结论 镉汞联合染毒引起的DNA损伤和细胞凋亡可能存在一定的协同效应,这可能是由于镉、汞诱导细胞发生氧化应激所致.     

亚砷酸钠对人黑色素瘤细胞活力和活性氧自由基生成及细胞凋亡的影响

目的探讨亚砷酸钠对人黑色素瘤(A375)细胞活力、活性氧(ROS)自由基生成及细胞凋亡的影响。方法以含0(对照)、1、5、10、20μmol/L亚砷酸钠的DMEM培养基作用于A375细胞24 h后,以阿尔玛蓝(Alamar Blue)还原法检测细胞活力水平,以流式细胞仪检测细胞ROS生成水平及细胞凋亡水平。结果与对照组比较,10、20μmol/L亚砷酸钠染毒组A375细胞活力水平较低,ROS的生成水平较高;仅20μmol/L亚砷酸钠染毒组A375细胞凋亡水平较高,差异均有统计学意义(P<0.05)。随着亚砷酸钠染毒浓度的升高,A375细胞活力呈下降趋势,ROS的生成和细胞凋亡水平呈上升趋势。结论亚砷酸钠可在致A375细胞ROS水平增高的同时,引起细胞凋亡。     

Calcium intake in the elderly: validation of a dietary questionnaire

Epidemiological studies of calcium and osteoporosis have been hampered by the lack of a suitable tool for assessing calcium intake. This report describes a new frequency and amount questionnaire for measuring present and past calcium intake in the elderly. The validity of the questionnaire was tested against two commonly used standards of dietary assessment, five-day duplicate diets and seven-day weighed dietary inventories. The resulting correlation coefficients were, respectively, r = 0.76 and r = 0.69, while that for repeatability was r = 0.84. Furthermore, the questionnaire categorized subjects into thirds of the distribution of intake with almost no gross misclassification. It is suggested that the present findings may be extended to the majority of normal, healthy elderly subjects, implying wide application for the questionnaire in the assessment of calcium intake in the elderly.     

The occurrence of antimicrobial substances in toilet,sink and shower drainpipes of clinical units: A neglected source of antibiotic residues

Antibiotics represent one of the most important drug groups used in the management of bacterial infections in humans and animals. Due to the increasing problem of antibiotic resistance, assurance of the antibacterial effectiveness of these substances has moved into the focus of public health. The reduction in antibiotic residues in wastewater and the environment may play a decisive role in the development of increasing rates of antibiotic resistance. The present study examines the wastewater of 31 patient rooms of various German clinics for possible residues of antibiotics, as well as the wastewater of five private households as a reference.To the best of our knowledge, this study shows for the first time that in hospitals with high antibiotic consumption rates, residues of these drugs can be regularly detected in toilets, sink siphons and shower drains at concentrations ranging from 0.02?μg·L^?1 to a maximum of 79?mg·L^?1. After complete flushing of the wastewater siphons, antibiotics are no longer detectable, but after temporal stagnation, the concentration of the active substances in the water phases of respective siphons increases again, suggesting that antibiotics persist through the washing process in biofilms. This study demonstrates that clinical wastewater systems offer further possibilities for the optimization of antibiotic resistance surveillance.     

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.     

深圳公立医院管理体制改革制度设计

深圳公立医院管理体制改革实行政事分开、管办分开,在理事会架构下按法定机构模式组建市医管中心,落实公立医院运营管理自主权.作者从当前公立医院管理体制的弊端入手,介绍了深圳市进行公立医院管理体制改革的基本思路及改革方案设计的主要举措,深入剖析了的改革方案的特点,并对改革效果进行了预测.     

Effects of nitrogen dioxide on red blood cells of rats: Changes in components of red cell membranes during in vivo exposure to NO2

Red cell membranes, prepared from red blood cells of rats exposed to 4, 10, or 20 ppm nitrogen dioxide (NO₂) for 1 to 10 days, were examined for evidence of changes in membrane components. Appreciable changes were not found in contents of phospholipid and cholesterol during exposure to 10 ppm NO₂. By contrast, protein content altered with the time of exposure. Moreover, changes in protein composition were observed by employing sodium dodecyl sulfate — polyacrylamide gel electrophoresis. Twenty-four-hour exposure to NO₂ at the concentration above 10 ppm resulted in a marked increase in the percentage of lysophosphatidylethanolamine (LysoPE) to the total phospholipids. The prolonged exposure to 10 ppm NO₂ gave rise to a further increase in LysoPE, whereas the percentage of phosphatidylethanolamine (PE) showed a gradual decrease. A 1-day exposure to 4.0 ppm NO₂ also caused an increase in sialic acid content and decreases in those of PE and hexose. In addition to contents of these components the percentage of LysoPE increased 5 days after exposure and the elevated values were maintained up to the end of exposure period. These results demonstrate that red blood cells in circulation exhibit different membrane properties in terms of lipid and carbohydrate composition during 10 days of exposure to 4.0 ppm NO₂.     

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.