亚砷酸钠对SV-HUC-1细胞NRF2通路影响

目的探讨亚砷酸钠(NaAsO_2)对人膀胱上皮细胞系SV-HUC-1细胞内核因子相关因子2(NRF2)活性的影响。方法时间效应实验以4μmol/L NaAsO_2分别处理SV-HUC-1细胞0(对照)、4、8、16、24 h;剂量效应实验设对照组和NaAsO_2处理组(1、2、4、8、10μmol/L);Western blot免疫印迹试验检测NRF2通路相关蛋白(NRF2、NQO1和HO1)表达水平。结果 4μmol/L NaAsO_2处理SV-HUC-1细胞4、8、16、24 h后,与对照组(0.68±0.03)比较,细胞内NRF2蛋白表达水平明显升高,16 h处理组NRF2蛋白表达最高(1.17±0.10),差异有统计学意义(P0.05);随着染砷剂量增加,NRF2、NQO1和HO1蛋白表达水平增强,与对照组NRF2(0.86±0.05)、NQO1(0.68±0.02)、HO1(0.09±0.01)比较,4和8μmol/L NaAsO_2处理组细胞内NRF2、NQO1、HO1蛋白表达水平分别为(1.12±0.01)和(1.16±0.11)、(0.93±0.01)和(1.15±0.19)、(1.28±0.01)和(1.30±0.02),均明显升高,差异均有统计学意义(均P0.05)。结论 NaAsO_2急性暴露能够活化NRF2通路,引起膀胱上皮细胞适应性抗氧化反应增强。     

3种抗氧化剂对亚砷酸钠染毒人膀胱上皮细胞血管内皮生长因子表达的拮抗作用研究

目的探讨抗氧化剂褪黑素(melatonin,MEL)、N-乙酰半胱氨酸(N-acetyl cysteine,NAC)、维生素C(Vitamin,VC)对砷诱导人正常膀胱上皮(SV-HUC-1)细胞血管内皮生长因子(vascular endothelial growth factor,VEGF)表达的拮抗作用。方法将处于对数生长期的SV-HUC-1细胞暴露于含终浓度分别为0(对照)、0.5、1、2、4、8、10μmol/L亚砷酸钠的F12K完全培养基染毒24 h,或者含终浓度分别为4、10μmol/L亚砷酸钠的F12K完全培养基染毒0(对照)、4、12、24、48、72 h;联合暴露组在加入含终浓度分为4μmol/L亚砷酸钠的F12K完全培养基前30 min分别加入1%二甲基亚砜(DMSO)和抗氧化剂MEL、VC、NAC(终浓度分别为0.5、1、1 mmol/L),染毒24 h。分别采用Western blot法和RT-PCR法检测SV-HUC-1细胞VEGF蛋白和mRNA的表达水平。结果 10μmol/L亚砷酸钠染毒组SV-HUC-1细胞VEGF mRNA的表达水平高于对照组,差异有统计学意义(P0.05);且随着亚砷酸钠染毒剂量的升高,SV-HUC-1细胞VEGF mRNA的表达水平呈上升趋势。与对照组比较,4μmol/L亚砷酸钠染毒12、24、48 h及10μmol/L亚砷酸钠染毒24和48 h后SV-HUC-1细胞VEGF mRNA的表达水平均升高,差异有统计学意义(P0.05);且随着亚砷酸钠染毒时间的延长,各剂量组SV-HUC-1细胞VEGF mRNA的表达水平均呈先上升后下降的趋势。与对照组比较,4μmol/L亚砷酸钠+DMSO染毒组SV-HUC-1细胞中VEGF蛋白的表达水平均增加,差异有统计学意义(P0.05)。与4μmol/L亚砷酸钠+DMSO染毒组比较,亚砷酸钠+NAC染毒组SV-HUC-1细胞中VEGF蛋白的表达水平较高,差异有统计学意义(P0.05);而亚砷酸钠与MEL和VC联合染毒组SV-HUC-1细胞中VEGF蛋白的表达水平无明显改变。结论砷能诱导人正常膀胱上皮细胞VEGF表达增加,NAC能增加VEGF表达。     

砷对人正常膀胱上皮细胞信号传导与转录激活因子3mRNA表达的影响

目的研究亚砷酸钠对人正常膀胱上皮(SV-HUC-1)细胞中信号传导与转录激活因子3(STAT3)m RNA表达的影响。方法将处于对数生长期的SV-HUC-1细胞分别进行急性染毒[暴露于含终浓度为0(对照)、1、2、4、8、10μmol/L亚砷酸钠的培养基染毒24 h]和慢性染毒[以含终浓度为0(对照)、0.5μmol/L亚砷酸钠的培养基染毒40代]。采用逆转录PCR(RT-PCR)方法检测细胞STAT3 m RNA表达情况。结果与对照组比较,4、8、10μmol/L亚砷酸钠暴露组SV-HUC-1细胞内STAT3 m RNA的表达水平均升高,差异均有统计学意义(P0.05);且随着亚砷酸钠染毒剂量的升高,SV-HUC-1细胞内STAT3 m RNA的表达水平呈先升高后下降的趋势。0.5μmol/L亚砷酸钠慢性暴露组SV-HUC-1细胞内STAT3m RNA的表达水平高于对照组,差异有统计学意义(P0.05)。结论砷可能通过调控STAT3的表达而在砷诱导的SVHUC-1细胞恶性转化中发挥一定作用。     

急性亚砷酸钠暴露对小鼠主动脉Nrf2通路的影响

目的研究急性亚砷酸钠暴露对小鼠主动脉NF-E2相关因子2(nuclear factor E2-related factor 2,Nrf2)通路的影响。方法选择健康成年清洁级雄性野生型C57BL/6小鼠作为实验动物。将15只小鼠按体重随机分成4组,分别为0(对照,n=3)及2、6、12h亚砷酸钠染毒组(n=4)。采用腹腔注射方式给予5 mg/kg亚砷酸钠溶液。将10只小鼠按体重随机分成3组,分别为对照(磷酸盐缓冲溶液,n=3)组和1.25 mg/kg(n=4)、5 mg/kg(n=3)亚砷酸钠染毒组。采用腹腔注射方式染毒6 h。检测小鼠主动脉中Nrf2及其下游基因谷氨酰半胱氨酸连接酶催化亚单位(GCLC)、谷氨酰半胱氨酸连接酶修饰亚单位(GCLM)以及NAD(P)H醌氧化还原酶(NQO1)m RNA的表达水平。结果与对照组相比,5 mg/kg亚砷酸钠染毒2 h小鼠主动脉GCLC m RNA的表达水平及染毒6 h小鼠主动脉GCLM、NQO1 m RNA的表达水平均较高,差异有统计学意义(P0.05);而亚砷酸钠染毒不同时间小鼠主动脉Nrf2 m RNA的表达水平无明显变化。且随着亚砷酸钠染毒时间的延长,小鼠主动脉Nrf2、GCLC、GCLM及NQO1 m RNA的表达水平均呈先上升后下降的趋势。与对照组相比,5 mg/kg亚砷酸钠染毒6 h小鼠主动脉GCLC、GCLM及NQO1 m RNA的表达水平均较高,差异有统计学意义(P0.05);而各剂量亚砷酸钠染毒6 h小鼠主动脉Nrf2 m RNA的表达水平均无明显改变。且随着亚砷酸钠染毒剂量的升高,小鼠主动脉Nrf2、GCLC、GCLM及NQO1 m RNA的表达水平均呈上升趋势。结论急性亚砷酸钠处理能激活小鼠主动脉Nrf2通路,提示急性无机砷暴露引起主动脉内发生氧化应激。     

无机砷对肝细胞转录因子Nrf2及其调控蛋白表达影响

目的探讨不同时间和不同浓度亚砷酸钠(NaAsO2)暴露对Chang肝细胞株NF-E2相关因子2(Nrf2)、及其调控的下游抗氧化酶NAD(P)H:醌氧化还原酶1(NQO1)和血红素单加氧酶-1(HO-1)蛋白表达的影响。方法25μmol/L NaAsO2作用Chang肝细胞2、4、6、12和24 h;或不同浓度的NaAsO2(10、25和50μmol/L)作用Chang肝细胞6 h,免疫印迹法(western blot)检测细胞内Nrf2、NQO1和HO-1的蛋白表达情况。结果 25μmol/L的NaAsO2可以明显诱导Chang肝细胞Nrf2、NQO1和HO-1的蛋白表达(P<0.01);Nrf2蛋白2 h开始明显诱导,4 h表达水平最高,此后随暴露时间的延长虽然表达有所下降,但持续至24 h仍明显高于对照组;NQO1的蛋白表达水平也从4 h开始增加并持续至24 h;HO-1的蛋白表达则从6 h开始明显诱导,且随暴露时间的继续延长表达持续上升,具有明显的时间-效应关系;10、25和50μmol/L NaAsO2染毒6 h,Nrf2、NQO1和HO-1的蛋白表达均随染毒剂量的增加而大量诱导,具有明显的剂量-效应关系(P<0.01)。结论 NaAsO2暴露能够诱导Chang肝细胞Nrf2、NQO1和HO-1蛋白表达增强,且具有一定的剂量-效应关系。     

抗氧化剂对砷诱导人正常膀胱上皮细胞HIF-1α 表达的影响[

目的探讨抗氧化剂对砷诱导人正常膀胱上皮细胞HIF-1α表达的影响。方法人膀胱上皮细胞(SVHUC-1)暴露于0、0.5、1、2、4、8、10μmol/L亚砷酸钠(Na As O2)24 h,RT-PCR检测HIF-1α的mRNA水平;选择4和10μmol/L剂量组,分别处理4、12、24、48、72 h,再以RT-PCR法检测HIF-1α的mRNA水平;SV-HUC-1细胞同时暴露于Na As O2和抗氧化剂N-乙酰半胱氨酸(NAC)、维生素C(VC),检测HIF-1α的蛋白含量。结果经砷处理后,SV-HUC-1细胞HIF-1α的mRNA含量显著升高(P0.05),并与染砷剂量呈显著剂量-反应关系;抗氧化剂NAC和VC均显著降低了HIF-1α的蛋白水平。结论砷能诱导人正常膀胱上皮细胞HIF-1α表达增加,抗氧化剂NAC和VC对砷诱导的HIF-1α表达具有显著的抑制作用。     

镉暴露对HepG2细胞NRF2信号通路影响

目的探讨镉暴露对HepG2细胞转录因子NF-E2相关因子2(NRF2)信号通路的影响。方法采用甲臢比色法测定CdCl_2(0、1、2.5、5、10、25、50、100、200μmol/L)处理24 h后,HepG2细胞活力变化;应用蛋白免疫印迹法检测CdCl_2(1、2、5、10、20μmol/L)处理细胞6 h后,NRF2蛋白水平;采用RT-q PCR方法检测10μmol/L CdCl_2处理细胞2、4、6、12、24 h后,GCLC、GCLM、HO1和AKR1C1 m RNA水平变化,检测CdCl_2(1、2、5、10、20μmol/L)处理细胞6 h后,GCLC、GCLM、HO1和AKR1C1 m RNA水平变化。结果 HepG2细胞活力随镉处理剂量升高而降低(P0.05);与对照组(0.60±0.01)比较,1、2、5、10、20μmol/L镉处理组HepG2细胞NRF2蛋白表达水平[分别为(0.65±0.01)、(1.37±0.04)、(1.94±0.05)、(2.24±0.07)、(2.22±0.05)]均明显升高(P0.05);与对照组比较,镉处理6 h时,HepG2细胞内GCLC、GCLM、HO1和AKR1C1 m RNA水平[分别为(45.76±7.04)、(114.21±5.23)、(59.52±1.50)、(674.13±27.12)]明显升高(P0.05);与对照组比较,5μmol/L镉处理组HepG2细胞内GCLC和GCLM m RNA水平[分别为(24.77±2.16)、(29.93±0.67)]升高,2μmol/L镉处理组HepG2细胞内HO1和AKR1C1 m RNA水平[分别(28.55±2.02)、(186.32±12.63)]升高(P0.05)。结论镉暴露能激活HepG2细胞系中NRF2信号通路。     

c-jun末端激酶在亚砷酸钠致人胚胎肝细胞损伤中的表达

目的探讨亚砷酸钠染毒对人胚胎肝(L-02)细胞中c-jun末端激酶(JNK)的变化。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、150μmol/L的亚砷酸钠溶液中培养24 h,采用四甲基偶氮唑蓝(MTT)法检测细胞生长情况,采用流式细胞术检测染毒24 h时的细胞周期及细胞凋亡率;采用蛋白杂交(Western-blot)法检测JNK及p-JNK的蛋白表达水平。结果与对照组相比,各浓度亚砷酸钠染毒组L-02细胞的存活率及G0-G1期构成比均较低,JNK、p-JNK的蛋白表达水平和S期构成比及凋亡率均较高;而G2-M期构成比在50μmol/L亚砷酸钠染毒组较低,在100、150μmol/L亚砷酸钠染毒组均较高,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细胞凋亡率及JNK和p-JNK蛋白的表达水平均呈上升趋势,细胞存活率呈下降趋势。结论亚砷酸钠诱导L-02细胞凋亡可能与JNK及p-JNK表达的增加有关。     

MAPKs信号通路在光气吸入性肺损伤中的表达及作用

目的 探讨丝裂原活化蛋白激酶(mitogen activated protein kinases,MAPKs)的亚通路信号蛋白-细胞外信号调节蛋白激酶(extracellular signal-regulated kinase,ERK1/2)、P38和c-氨基末端蛋白激酶(c-Jun N-terminal kinase,JNK)在大鼠光气吸入肺损伤组织中的表达及各通路在光气吸入性肺损伤中的作用.方法 选取30只雄性Wistar大鼠随机分成空气对照组、光气吸入组、PD98059(ERK1/2特异性阻断剂)、SB203580(P38特异性阻断剂)和SP600125(JNK特异性阻断剂)干预组,每组6只,应用定向流动光气吸入装置,复制大鼠光气(8.33 L/mg)吸入性肺损伤的模型,空气对照组吸入空气,3个干预组均在光气(8.33 L/mg)吸入前给予PD98059、SB203580、SP600125.分别采用免疫组化及蛋白质印迹( Western blot)法检测肺组织MAPKs(ERK1/2、P38、JNK)蛋白及磷酸化蛋白p-MAPKs (p-ERK 1/2、p-P38、p-JNK)的定性定量表达.观察肺组织病理学改变、计数支气管灌洗液(BALF)中中性粒细胞数、测定肺湿干比.结果 空气对照组仅肺泡上皮细胞及气道上皮细胞见少量p-ERK1/2、p-P38、p-JNK阳性表达;光气吸入组p-ERK1/2、p-P38、p-JNK阳性细胞数明显增多,广泛分布于肺内细胞:肺泡上皮细胞、气道上皮细胞、胸膜间皮细胞、浸润炎细胞及间质纤维细胞;干预组p-ERK1/2、p-P38、p-JNK阳性细胞数减少.各组ERK、P38、JNK的表达无明显变化;光气吸入组较空气对照组p-P38、p-JNK蛋白表达增强,3个干预组的p-ERK1/2、p-P38、p-JNK的蛋白表达水平均低于光气吸入组,差异均有统计学意义(P＜0.05,P＜0.01).与空气对照组[中性粒细胞计数:(2.05±0.75)×104,肺湿干比:(3.64％±0.72％)]比较,光气吸入组肺损伤程度严重,表现出肺损伤的典型病理学特征,且BALF中中性粒细胞数[(10.78±2.16)×104]增多,肺湿干比(7.65％±0.58％)升高,SP600125干预组和SB203580干预组BALF中中性粒细胞数[SP600125组:(7.86±2.12)×104,SB203580组:(8.43±1.51)×104]和肺湿干比[SP600125组:(6.10％±0.97％),SB203580组:(6.09％±1.43％)]降低,差异均有统计学意义(P＜0.05,P＜0.01).结论 光气吸入可能激活MAPK信号通路,通过p-MAPKs表达增加在光气吸入后的肺损伤中发挥作用,其中以p-P38、p-JNK活性变化为主.     

草苁蓉环烯醚萜苷对肝癌抑制作用

目的探讨草苁蓉环烯醚萜苷(IGBR)对二乙基亚硝胺(DEN)诱发大鼠肝癌细胞凋亡的影响及其可能作用机制。方法 Wistar雄性大鼠随机分为对照组和模型组、5–氟尿嘧啶(5-FU)组、IGBR组,除对照组外,其余大鼠第1天给予腹腔注射DEN 200 mg/kg 1次,自由饮用0.05%的DEN水溶液;5-FU组大鼠腹腔注射25 mg/kg 5-FU,每周3次;IGBR组大鼠灌胃500 mg/kg IGBR每日1次。实验第12、20、28周末分批处死动物,TUNEL法检测肝细胞凋亡,Western blot法检测肝组织中Bax、Bcl-2和丝裂原活化蛋白激酶(MAPK)、磷脂酰肌醇3激酶/蛋白激酶B(PI3K/Akt)通路相关蛋白表达。结果与对照组比较,模型组大鼠肝细胞凋亡指数[(12.3±0.4)%]明显升高;与模型组比较,5-FU组与IGBR组大鼠肝细胞凋亡指数[分别为(22.3±0.2)%、(22.2±0.1)%]明显升高(P0.05),5-FU组与IGBR组之间差异无统计学意义(P0.05)。与对照组比较,模型组大鼠肝组织中p-ERK、p-Akt表达水平下降、p-JNK、p-p38表达水平升高,ERK、p38、JNK、Akt表达无显明变化;与模型组比较,5-FU组与IGBR组大鼠肝组织中Bcl-2和p-ERK、p-Akt表达水平下降,Bax和p-JNK、p-p38表达水平升高。结论 IGBR可通过MAPK、PI3K/Akt信号通路,调节Bax和Bcl-2表达,诱发DEN大鼠肝癌细胞凋亡。     

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.