壬基酚对小鼠卵巢氧化损伤效应的研究

为探讨壬基酚(NP)对雌性小鼠卵巢的氧化损伤效应,将40只健康SPF级雌性昆明小鼠随机分为4组,分别为对照(玉米油)组和25、50、100 mg/kg NP染毒组,每组10只。采用灌胃方式进行染毒,染毒容量为0.01 ml/g,每天1次,每周连续染毒5 d,连续染毒8周。测定小鼠卵巢总抗氧化能力(T-AOC)、超氧化物歧化酶(SOD)活力和丙二醛(MDA)、还原型谷胱甘肽(GSH)的含量,并观察卵巢内总卵泡数、初级卵泡数及成熟卵泡数。结果显示,与对照组比较,50、100 mg/kg NP染毒组小鼠卵巢T-AOC活力及100 mg/kg NP染毒组小鼠卵巢SOD的活力和GSH的含量均显著降低;而各剂量NP染毒组小鼠卵巢MDA的含量均较高,差异均有统计学意义(P0.05);且随着NP染毒剂量的升高,小鼠卵巢SOD的活力和GSH的含量均呈下降趋势,而MDA含量呈上升趋势,T-AOC呈先上升后下降趋势。与对照组比较,50、100 mg/kg NP染毒组小鼠卵巢内总卵泡数及25 mg/kg NP染毒组小鼠卵巢内初级卵泡数均较高,而100 mg/kg NP染毒组小鼠卵巢内成熟卵泡较低,差异均有统计学意义(P0.05);且随着NP染毒剂量的升高,小鼠卵巢内的总卵泡数呈上升趋势,而初级卵泡数和成熟卵泡数均呈先上升后下降的趋势。提示NP可导致小鼠卵巢组织发生明显的氧化损伤。     

纳米氧化石墨烯一次性染毒对小鼠肝脏的急性氧化损伤作用

目的探讨纳米氧化石墨烯(nano-GO)对小鼠肝脏的急性氧化损伤作用。方法将80只健康清洁级ICR小鼠随机分为对照(高纯水)组和0.35 mg/kg(1/16 LD50)、0.70 mg/kg(1/8 LD50)、1.40 mg/kg(1/4 LD50)nano-GO染毒组,每组20只,雌雄各半。采用1次性尾静脉注射染毒,染毒容量为10 ml/kg。分别于注射3、15 d后,检测小鼠肝脏组织超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)活力和丙二醛(MDA)含量。结果染毒3 d后,与对照组比较,各剂量nano-GO染毒组雌性小鼠和0.35 mg/kg nano-GO染毒组雄性小鼠肝脏的MDA含量及各剂量nano-GO染毒组小鼠肝脏的GSH-Px活力以及0.35、0.70 mg/kg nano-GO染毒组雄性小鼠肝脏的SOD活力均升高,0.70、1.40 mg/kg nano-GO染毒组雄性小鼠肝脏MDA含量和0.35、0.70 mg/kg nano-GO染毒组雌性小鼠肝脏的SOD活力均下降,差异均有统计学意义(P0.05)。染毒15 d后,与对照组比较,各剂量nano-GO染毒组小鼠肝脏的SOD活力升高,0.70 mg/kg和1.40 mg/kg nano-GO染毒组小鼠肝脏的GSH-Px活力下降,差异均有统计学意义(P0.05);而各剂量nano-GO染毒组小鼠肝脏的MDA含量均无明显改变。结论一次性尾静脉注射nano-GO后,肝脏可产生脂质过氧化作用,干扰小鼠肝脏抗氧化酶的活力。     

纳米TiO_2对雌性小鼠的生殖毒性

目的探讨纳米TiO_2对雌性小鼠的生殖毒性效应。方法将60只健康SPF级雌性ICR小鼠随机分为4组,分别为对照(生理盐水)组和10、50、100 mg/kg/d纳米TiO_2染毒组,每组15只,连续28天灌胃染毒。检测小鼠生殖脏器系数、阴道涂片观察动情周期、HE染色观察卵巢组织变化、试剂盒测定卵巢中超氧化物歧化酶(SOD)、丙二醛(MDA)、过氧化物酶(POD)及过氧化氢酶(CAT)水平。结果染毒后,与对照相比,50和100 mg/kg/d染毒组,小鼠动情前期明显缩短(P0.05),动情后期显著延长(P0.05);卵巢组织HE切片观察发现,纳米TiO_2染毒组中,小鼠卵巢颗粒细胞和黄体均出现不同程度的结构疏松和炎症细胞浸润;氧化应激测定结果表明,50和100 mg/kg/d染毒组小鼠卵巢SOD活性显著低于对照组(P0.05);与对照相比,各染毒组MDA含量均显著增加(P0.05);POD和CAT活性分别在100和50、100 mg/kg/d剂量组明显高于对照组(P0.05)。结论纳米TiO_2可引起小鼠动情周期紊乱及卵巢组织的氧化损伤。     

邻苯二甲酸二丁酯和邻苯二甲酸二(2-乙基已基)酯联合染毒对雌性大鼠的生殖毒性

目的 探讨邻苯二甲酸二丁酯(di-n-butyl phthalate,DBP)和邻苯二甲酸二(2-乙基已基)酯(di-2-ethylhexylphthalate,DEHP)联合染毒对雌性大鼠生育力的影响.方法 将32只健康成年清洁级雄性SD大鼠按2×2析因设计随机分为4组,分别为阴性对照(玉米油)组、DBP染毒组(1/20 LD50,1.0g/kg)、DEHP染毒组(1/20 LD50,1.7 g/kg)和DBP(1.0 g/kg)+DEHP(1.7 g/kg)染毒组,每组8只.采用灌胃方式进行染毒,染毒容量为5 ml/kg,每天1次,每周5 d,连续染毒8周.末次染毒24 h后,测量大鼠体重、肝脏、子宫和卵巢脏器湿重并计算脏器系数.测定血清中氧化损伤指标[超氧化物歧化酶(SOD)活力、还原性谷胱甘肽(GSH)含量、谷胱甘肽过氧化物酶(GSH-Px)活力]、子宫一氧化氮合酶(nitric oxide synthase;NOS)活力和血清中雌性激素[孕酮(P)、雌二醇(E2)、黄体生成素(LH)和促卵泡激素(FSH)]水平,并观察卵巢组织形态学改变和卵巢组织各级卵泡数目.结果 DBP和DEHP联合染毒对雌性大鼠体重增长、子宫系数、血清GSH-Px活力、LH和FSH水平无交互作用;可使卵巢的脏器系数、血清SOD活力、GSH含量、P、E2水平、子宫NOS活力降低,肝脏的脏器系数和闭锁卵泡构成比升高,交互作用均有统计学意义(P<0.05或P<0.01);表现为协同作用.结论 DBP和DEHP联合染毒对雌性大鼠具有明显的生殖毒性作用.     

金属硫蛋白对镍铬联合染毒小鼠肝脏损伤的拮抗作用

目的研究硫酸镍+重铬酸钾联合染毒对小鼠肝脏损伤的影响及金属硫蛋白(MT)的拮抗作用。方法将50只健康SPF级昆明小鼠按体重随机分为5组,分别为溶剂对照组(生理盐水)、镍铬(1.0 mg/kg硫酸镍+0.5 mg/kg重铬酸钾)联合染毒组和低、中、高剂量MT保护(1.0 mg/kg硫酸镍+0.5 mg/kg重铬酸+5.0、10.0、20.0 mg/kg MT)组,每组10只,雌雄各半。采取灌胃方式进行染毒,染毒容量为10 ml/kg,每天1次,连续染毒21 d。检测小鼠丙氨酸氨基转移酶(ALT)、天门冬氨酸氨基转移酶(AST)、γ-谷氨酰转肽酶(GGT)活力及肝组织超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)活力和丙二醛(MDA)、谷胱甘肽(GSH)含量。结果与溶剂对照组比较,镍铬联合染毒组小鼠血清AST、ALT、GGT的活力均增高,差异均有统计学意义(P0.05)。各剂量MT保护组小鼠血清AST、ALT、GGT的活力均低于镍铬联合染毒组,差异均有统计学意义(P0.05);且随着MT染毒剂量的升高,MT保护组小鼠血清AST、ALT、GGT的活性均呈下降趋势。与溶剂对照组比较,镍铬联合染毒组小鼠肝组织SOD、GSH-Px活力和GSH含量均下降,而MDA含量升高,差异均有统计学意义(P0.05)。与镍铬联合染毒组比较,各剂量MT保护组小鼠肝组织SOD、GSH-Px活力和GSH含量均升高,而MDA含量均降低,差异均有统计学意义(P0.05),且随着MT染毒剂量的升高,MT保护组小鼠肝组织SOD、GSH-Px活力和GSH含量均呈上升趋势,而MDA含量呈下降趋势。结论 MT对镍铬联合染毒所致小鼠肝脏损伤有较好的拮抗作用,其作用机制可能与MT抗氧化作用有关。     

毒死蜱对小鼠卵巢的毒性及其凋亡基因表达水平的影响

目的研究毒死蜱对小鼠卵巢的生殖毒性及对相关凋亡基因表达水平的影响。方法将40只健康6周龄无生育史清洁级ICR雌性小鼠按体重随机分为4组,分别为阴性对照(玉米油)组和7.5、15.0、30.0 mg/kg毒死蜱染毒组(采用灌胃方式染毒,染毒容量为10 ml/kg,每天1次,每周连续染毒6 d),每组10只。染毒时间为2周。统计各期卵泡构成和颗粒细胞凋亡情况,检测相关凋亡基因的表达水平。结果与阴性对照组比较,15.0、30.0 mg/kg毒死蜱染毒组原始卵泡以及30.0 mg/kg毒死蜱染毒组闭锁卵泡的构成比均较高,15.0、30.0 mg/kg毒死蜱染毒组生长卵泡以及30.0 mg/kg毒死蜱染毒组成熟卵泡的构成比均较低,差异均有统计学意义(P<0.05)。且随着毒死蜱染毒剂量的升高,原始卵泡的构成比呈上升趋势,成熟卵泡的构成比呈下降趋势,生长卵泡的构成比呈先上升后下降的趋势,而闭锁卵泡的构成比呈先下降后上升的趋势。仅30.0 mg/kg毒死蜱染毒组卵巢颗粒细胞凋亡指数显著增高,差异有统计学意义(P<0.05);且随着毒死蜱染毒剂量的升高,小鼠卵巢颗粒细胞凋亡指数呈上升趋势。15.0、30.0 mg/kg毒死蜱染毒组小鼠卵巢组织中mch3 mRNA的表达增高,bcl-2 mRNA的表达下降,差异均有统计学意义(P<0.05)。且随着毒死蜱染毒剂量的升高,小鼠卵巢组织中mch3 mRNA的表达呈上升趋势,bcl-2 mRNA的表达呈下降趋势。结论毒死蜱具有雌性生殖毒性,通过上调mch3的表达和下调bcl-2基因的表达,促进颗粒细胞凋亡,诱导卵泡闭锁,引起卵巢损伤,造成小鼠生育力降低。     

邻苯二甲酸二丁酯和邻苯二甲酸二(2-乙基己基)酯联合染毒对雌性大鼠的生殖毒性

目的探讨邻苯二甲酸二丁酯(di-n-butyl phthalate,DBP)和邻苯二甲酸二(2-乙基己基)酯(di-2-ethyl hexylphthalate,DEHP)联合染毒对雌性大鼠生育力的影响。方法将32只健康成年清洁级雄性SD大鼠按2×2析因设计随机分为4组,分别为阴性对照(玉米油)组、DBP染毒组(1/20LD50,1.0g/kg)、DEHP染毒组(1/20LD50,1.7g/kg)和DBP(1.0g/kg)+DEHP(1.7g/kg)染毒组,每组8只。采用灌胃方式进行染毒,染毒容量为5ml/kg,每天1次,每周5d,连续染毒8周。末次染毒24h后,测量大鼠体重、肝脏、子宫和卵巢脏器湿重并计算脏器系数。测定血清中氧化损伤指标[超氧化物歧化酶(SOD)活力、还原性谷胱甘肽(GSH)含量、谷胱甘肽过氧化物酶(GSH-Px)活力]、子宫一氧化氮合酶(nitric oxide synthase;NOS)活力和血清中雌性激素[孕酮(P)、雌二醇(E2)、黄体生成素(LH)和促卵泡激素(FSH)]水平,并观察卵巢组织形态学改变和卵巢组织各级卵泡数目。结果 DBP和DEHP联合染毒对雌性大鼠体重增长、子宫系数、血清GSH-Px活力、LH和FSH水平无交互作用;可使卵巢的脏器系数、血清SOD活力、GSH含量、P、E2水平、子宫NOS活力降低,肝脏的脏器系数和闭锁卵泡构成比升高,交互作用均有统计学意义(P0.05或P0.01);表现为协同作用。结论 DBP和DEHP联合染毒对雌性大鼠具有明显的生殖毒性作用。     

Antiagonizing Effect of Lycopene on Bromobenzene-induced Lipid Peroxidation in Mice

目的 探讨番茄红素对溴代苯诱导小鼠脂质过氧化损伤的拮抗作用.方法 将50只健康成年SPF级昆明雄性小鼠随机分为5组,即对照组、溴代苯模型组和低、中、高剂量番茄红素+溴代苯组,每组10只.低、中、高剂量番茄红素+溴代苯组小鼠经口灌胃浓度分别为0.33、0.67和2.00 g/L的番茄红素溶液,对照组和溴代苯模型组灌胃等体积的溶剂(含98％水、0.8％甘油、0.7％无水乙醇、0.5％玉米油),染毒容量为0.02 ml/g,每天1次,连续染毒30d;番茄红素暴露结束0.5 h后,测定红细胞超氧化物歧化酶(SOD)活力、全血谷胱甘肽过氧化物酶(GSH-Px)活力及总抗氧化能力(TAOC).番茄红素暴露结束3h后,除对照(橄榄油)组外,其余4组立即一次性灌胃染毒0.4mg/kg的溴代苯溶液,染毒容量为0.01 ml/g,22 h后,测定肝脏中丙二醛(MDA)含量和SOD、GSH-Px活力及T-AOC.结果 番茄红素暴露后,与溴代苯模型组相比,中、高剂量番茄红素+溴代苯组小鼠红细胞SOD活力、全血GSH-Px活力及全血T-AOC显著升高(P＜0.05,P＜0.01);溴代苯染毒后,与溴代苯模型组相比,中、高剂量番茄红素+澳代苯组小鼠肝脏中SOD活力、GSH-Px活力及T-AOC明显增强(P＜0.05,P＜0.01),MDA含量显著下降(P.＜0.05,P＜0.01).随着番茄红素暴露剂量的升高,小鼠肝脏中MDA含量呈下降趋势,而血液及肝脏中SOD、GSH-Px活力及T-AOC呈上升趋势.结论 番茄红素对溴代苯引起的小鼠脂质过氧化损伤具有一定的拮抗作用.     

番茄红素对溴代苯诱导小鼠脂质过氧化损伤的拮抗作用

目的探讨番茄红素对溴代苯诱导小鼠脂质过氧化损伤的拮抗作用。方法将50只健康成年SPF级昆明雄性小鼠随机分为5组,即对照组、溴代苯模型组和低、中、高剂量番茄红素+溴代苯组,每组10只。低、中、高剂量番茄红素+溴代苯组小鼠经口灌胃浓度分别为0.33、0.67和2.00 g/L的番茄红素溶液,对照组和溴代苯模型组灌胃等体积的溶剂(含98%水、0.8%甘油、0.7%无水乙醇、0.5%玉米油),染毒容量为0.02 ml/g,每天1次,连续染毒30 d;番茄红素暴露结束0.5 h后,测定红细胞超氧化物歧化酶(SOD)活力、全血谷胱甘肽过氧化物酶(GSH-Px)活力及总抗氧化能力(T-AOC)。番茄红素暴露结束3 h后,除对照(橄榄油)组外,其余4组立即一次性灌胃染毒0.4 mg/kg的溴代苯溶液,染毒容量为0.01 ml/g,22 h后,测定肝脏中丙二醛(MDA)含量和SOD、GSH-Px活力及T-AOC。结果番茄红素暴露后,与溴代苯模型组相比,中、高剂量番茄红素+溴代苯组小鼠红细胞SOD活力、全血GSH-Px活力及全血T-AOC显著升高(P<0.05,P<0.01);溴代苯染毒后,与溴代苯模型组相比,中、高剂量番茄红素+溴代苯组小鼠肝脏中SOD活力、GSH-Px活力及T-AOC明显增强(P<0.05,P<0.01),MDA含量显著下降(P<0.05,P<0.01)。随着番茄红素暴露剂量的升高,小鼠肝脏中MDA含量呈下降趋势,而血液及肝脏中SOD、GSH-Px活力及T-AOC呈上升趋势。结论番茄红素对溴代苯引起的小鼠脂质过氧化损伤具有一定的拮抗作用。     

反式脂肪酸对小鼠大脑抗氧化系统及ATP酶的影响

目的探讨反式脂肪酸对小鼠大脑抗氧化系统及ATP酶的影响。方法将48只健康SPF级昆明系雄性小鼠随机分为4组,分别为对照组和25、50、100 mg/kg反式脂肪酸染毒组,每组12只。采用灌胃方式进行染毒,染毒容量均为10ml/kg,每天1次,连续染毒12周。测定小鼠脑组织中的超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)、过氧化氢酶(CAT)、ATP酶的活力和丙二醛(MDA)、总蛋白的含量。结果与对照组相比,各剂量反式脂肪酸组小鼠脑组织中的抗氧化酶SOD、GSH-Px、CAT活力均降低,而脂质过氧化物MDA的含量升高;Na~+K~+-ATP酶和Ca~(2+)Mg~(2+)-ATP酶活力均降低,差异均有统计学意义(P0.05)。结论反式脂肪酸的摄入会引起小鼠脑组织抗氧化系统受损,同时,会降低脑组织中ATP酶的活力。     

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.     

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.     

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.     

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.