虾青素对四氯化碳致小鼠急性肝损伤保护作用

目的 研究虾青素对四氯化碳(CCl4)所致小鼠急性化学肝损伤的保护作用.方法 雄性昆明种小鼠60只,随机分为正常对照组、急性化学性肝损伤模型组、联苯双酯(15 mg/kg)阳性对照组以及虾青素10,15,20mg/kg剂量组,共6组.测定各组小鼠肝脏系数、血清中丙氨酸氨基转移酶(ALT)、天门冬氨酸氨基转移酶(AST)、超氧化物歧化酶(SOD)和谷胱甘肽过氧化物酶(GSH-Px)活性与丙二醛(MDA)含量;测定肝组织中SOD、GSH-Px活性、MDA含量以及组织病理系数.结果 虾青素3个剂量组小鼠血清SOD由低到高依次为(110.18±14.28),(138.09±17.81),(170.19±20.20)U/(mg pro);肝组织SOD由低到高依次为(141.52±28.29),(172.20±29.24),(200.12±33.42)U/(mg pro);与模型组血清(74.52±14.40)U/(mg pro)、肝组织(102.29±34.29)U/(mg pro)比较均明显升高(P<0.01).虾青素3个剂量组小鼠血清GSH-Px活性由低到高次为(63.30±11.01),(72.40±10.77),(90.17±11.29)U/(mg pro);肝组织GSH-Px活性由低到高依次为(112.29±25.41),(142.96±24.13),(170.38±26.34)U/(mg pro);与模型组血清(60.13±10.28)U/(mg pro)、肝组织(110.69±24.26)U/(mg pro)比较均明显升高(P<0.01).虾青素3个剂量组小鼠血清ALT由低到高依次为(99.29±5.27),(83.50±5.12),(68.12±5.12)U/L;血清AST活性由低到高依次为(80.49±4.28),(64.20±4.10),(52.21±4.42)U/L,与模型组血清ALT(108.02±15.06)U/L、血清AST活性(97.28±12.28)U/L比较明显降低;血清与肝组织MDA含量明显降低,差异均有统计学意义(P<0.01),并能不同程度地改善肝脏病理组织损伤.结论 虾青素对CCl4所致急性化学性肝损伤具有预防性保护作用.     

花锚中3种(口山)酮苷对小鼠肝损伤保护作用

目的 研究花锚提取物中3种(口山)酮苷对肝脏保护作用.方法 用CCl4灌胃小鼠,建立急性肝损伤动物模型,观察其肝脏组织形态,测定肝脏系数,血清中谷丙转氨酶、谷草转氨酶活性和肝糖元含量,研究3种(口山)酮苷对小鼠肝损伤的保护作用.结果 模型组中小鼠的血清谷丙转氨酶(ALT)、谷草转氨酶(AST)活性、肝脏系数、肝糖元A值分别为(1045.61±47.82),(1323.52±230.22)U/L,(0.062±0.0041),(0.062±0.013);与模型组比较,花锚中3种(口山)酮苷高剂量组(10 mg/ml)对小鼠实验性肝损伤均有明显的修复作用,能降低CCl4所致肝损伤小鼠的肝脏系数、血清ALT、AST活性,并提高肝糖元含量(P<0.01);化合物A、B、C中剂量组(5 mg/ml)的肝糖元A值分别为(0.072±0.011),(0.077±0.015),(0.078±0.012),与模型组相比均明显升高(P<0.05),其余各项指标与模型组比较,差异均有统计学意义(P<0.01);与模型组比较,化合物B低剂量组(1 mg/ml)可有效降低小鼠的肝脏系数及血清AST活性(P<0.05),化合物C低剂量组可明显降低小鼠血清AST活性(P<0.01),对ALT活性的升高也有较好的抑制作用(P<0.05),而其他给药组与模型组比较,差异均无统计学意义.结论 花锚中3种(口山)酮同苷均有较好的保肝作用,为花锚保护肝脏的有效成分、且具有一定的量效关系.     

人参皂苷Rg1对小鼠免疫性肝损伤保护作用

目的探讨人参皂苷Rg1对小鼠免疫性肝损伤的保护作用及机制。方法实验设Rg1高、中、低剂量(60、30、15 mg/kg),灌胃给予15 d,尾静脉注射20 mg/kg刀豆蛋白A制备免疫性肝损伤小鼠模型;采用自动生化分析仪测定小鼠血清中谷草转氨酶(AST)、谷丙转氨酶(ALT)活性;酶联免疫吸附实验测定小鼠血清中肿瘤坏死因子(TNF-α)、干扰素(IFN-γ)水平,并进行肝组织病理学观察。结果与对照组比较,模型组小鼠血清中AST、ALT含量[分别为(235.5±79.9)、(262.1±63.9)U/L]及TNF-α、IFN-γ水平[分别为(46.3±13.3)、(165.3±86.1)pg/m L]明显升高(P<0.01);与模型组比较,高剂量Rg1组小鼠血清中AST、ALT含量[分别为(57.1±19.9)、(44.1±16.2)U/L]及TNF-α、IFN-γ水平[(12.9±6.1)、(55.06±29.5)pg/m L]明显下降(P<0.01);组织学观察显示,Rg1各剂量组小鼠肝损伤程度明显轻于模型组。结论 Rg1对小鼠免疫性肝损伤具有一定保护作用,其机制可能与降低炎性细胞因子、减轻T淋巴细胞毒性作用有关。     

灵芝三萜对化学性肝损伤保护作用研究

目的探讨服用灵芝三萜对小鼠因CCl4诱导的肝损伤的保护作用。方法连续30d给予动物受试物后,模型组及各剂量组动物给予3.2mg/ml的CCl4染毒,测定ALT、AST,并取肝脏进行组织病理学检查。结果灵芝三萜可明显抑制CCl4引起小鼠血清谷丙转氨酶(ALT)和谷草转氨酶(AST)的升高,试验结束时,模型组ALT值为9658.5U/L,中、高剂量组分别为5899.2、3773.3U/L;模型组AST值为4962.8U/L,高剂量组为1999.9U/L,并能改善和恢复肝脏组织的病理指标。结论灵芝三萜对由CCl4引起的肝脏损伤有较好的保护作用。     

软肝冲剂对四氯化碳致小鼠肝损伤的保护作用

目的观察软肝冲剂对四氯化碳(CCl4)诱导的小鼠肝纤维化模型的保护作用。方法将60只C57B/L小鼠随机分为空白对照组、模型组、秋水仙碱对照组、软肝冲剂低剂量组和软肝冲剂高剂量组,每组12只。空白对照组腹腔注射100%花生油1 ml/kg,每周2次,共10周;其余各组均给予腹腔注射含20%CCl4的花生油1 ml/kg,每周2次,共10周造模;第3周起秋水仙碱对照组予秋水仙碱0.1 mg/(kg·d)灌胃,软肝冲剂低、高剂量组分别予软肝冲剂1 g/(kg·d)、5 g/(kg·d)灌胃。在第10周通过摘除眼球取血,检测小鼠血清中透明质酸(HA)、层粘连蛋白(LN)、三型前胶原(PCⅢ)、四型胶原(Ⅳ-C)、丙氨酸转氨酶(ALT)、天门冬氨酸转氨酶(AST)含量,检测肝脏组织中超氧化物歧化酶(SOD)和丙二醛(MDA)的含量,计算肝脏指数,观察小鼠肝脏的HE染色病理组织学改变。结果模型组小鼠血清中HA、LN、PCⅢ、Ⅳ-C、ALT和AST含量分别为(480.11±62.12)μg/L、(411.65±30.63)μg/L、(454.12±41.81)μg/L、(311.15±31.61)μg/L、(140.4±9.8)U/L和(198.2±9.7)U/L,均明显高于其它各组(P0.05);肝脏组织中SOD[(122.53±7.68)U/mg]低于空白对照组(P0.05);MDA[(5.59±0.33)nmol/mg]高于空白对照组(P0.05);肝脏指数[(4.7±1.5)%]高于空白对照组(P0.05)。病理切片显示肝细胞坏死并出现脂肪空泡、纤维组织增生和炎细胞浸润。软肝冲剂低剂量组与秋水仙碱组治疗效果相似。软肝冲剂高剂量组效果较好,小鼠血清中HA、LN、PCⅢ、Ⅳ-C、ALT和AST含量分别为(143.21±21.53)μg/L、(139.11±35.23)μg/L、(134.45±24.77)μg/L、(119.32±29.34)μg/L、(45.4±6.3)U/L和(53.6±7.1)U/L,均明显低于模型组(P0.05);肝脏组织中SOD[(189.5±7.5)U/mg]高于模型组(P0.05),MDA[(2.45±0.33)nmol/mg]低于模型组(P0.05);肝脏指数[(3.4±0.4)%]低于模型组(P0.05);病理检查显示肝脏组织中无炎性浸润、脂肪空泡和无纤维组织沉积。结论软肝冲剂可以改善肝脏功能,保护肝细胞和抑制肝纤维化,减轻CCl4诱导小鼠肝纤维化程度。     

染料木素对小鼠急性肝损伤的保护作用

目的 观察染料木素(genistein,GEN)对小鼠急性肝损伤的保护作用.方法 采用健康昆明种小鼠,以灌胃的方法连续7 d给予不同浓度GEN或联苯双酯,末次给药1 h后,腹腔注射0.1%CCl4建立小鼠急性肝损伤模型,染毒后16 h取肝脏,分别制备10%、1%肝匀浆,测定肝匀浆中丙二醛(MDA)含量、天冬氨酸转氨酶(AST)与丙氨酸转氨酶(ALT)活力,并计算AST/ALT比值和观察肝损伤病理学变化.结果 GEN剂量组的MDA含量分别为(730.95±78.28)、(650.00±87.26)和(479.17±52.79)nmol/g,均明显低于模型组,差异有统计学意义(P＜0.05或P＜0.01),3个GEN剂量组的AST、ALT活力与AST/ALT比值均明显高于模型组,差异有统计学意义(P＜0.05或P＜0.01),GEN剂量组肝脏病理性损伤减轻.结论 GEN对小鼠急性肝损伤具有一定的保护作用.     

萱草花黄酮对免疫性肝损伤小鼠保护作用及机制

目的探讨萱草花黄酮对免疫性肝损伤小鼠保护作用及凋亡相关基因bax、bcl-2表达变化。方法使用卡介苗和脂多糖制备小鼠免疫性肝损伤模型,将60只昆明小鼠随机分为对照组、模型组、低、中、高剂量萱草花黄酮(15、30、60 mg/kg)组。苏木素-伊红染色观察肝组织病理损伤程度;比色法测定肝组织中超氧化物歧化酶(SOD)、丙二醛和谷胱甘肽过氧化物酶(GSH-Px)含量;生化分析仪检测血清中谷丙转氨酶(ALT)含量;免疫组化法检测肝脏bax、bcl-2表达。结果与对照组比较,模型组小鼠血清中ALT水平[(105.48±46.34)U/L]、丙二醛含量[(8.57±0.54)nmol/mgprot]明显升高,SOD与GSH-Px活力[分别为(168.14±13.21)、(95.32±1.48)U/mgprot]明显下降(P0.01);与模型组比较,30、60 mg/kg萱草花黄酮组小鼠血清中ALT水平[分别为(56.38±26.31)、(59.77±13.34)U/L]、丙二醛含量[分别为(5.37±0.34)、(5.52±0.38)nmol/mgprot]降低(P0.05),SOD与GSH-Px活力[分别为(197.40±25.22)、(249.41±24.08)与(107.32±1.83)、(114.24±1.41)U/mgprot]升高(P0.05);与对照组比较,模型组小鼠肝脏bax基因表达上调,bcl-2基因表达下调(P0.0 5);与模型组比较,萱草花黄酮小鼠肝脏bax表达下调,bcl-2表达上调(P0.05)。结论萱草花黄酮对小鼠免疫性肝损伤具有一定保护作用,其机制可能与提高小鼠抗氧化能力、下调促凋亡基因bax表达、上调抗凋亡基因bcl-2表达有关。     

藏茵陈对小鼠冠状病毒性肝炎细胞caspase-3影响

目的观察小鼠冠状病毒性肝炎肝细胞中caspase-3介导的凋亡机制变化,探讨藏茵陈对其干预作用及相关机制。方法将24只小鼠随机分成对照组、模型组、阳性对照组和藏茵陈组,造模成功后用赖氏法测定小鼠血清肝功能2项,苏木素-伊红染色光镜观察小鼠肝脏病理变化,用酶标仪检测肝匀浆caspase-3活性,用荧光定量PCR检测肝组织中Fas和caspase-3 mRNA含量。结果与对照组比较,模型组小鼠ALT、AST活力分别为(225.349±9.904)、(180.823±17.34)U/L,明显升高;病理切片显示肝脏损伤明显,caspase-3活性(0.371±0.051)、Fas和caspase-3 mRNA含量(1.93±0.08、0.867±0.102)均明显升高;藏茵陈干预后ALT、AST分别为(181.906±20.164)和(139.824±12.153)U/L,Fas和caspase-3 mRNA含量为(1.673±0.047)和(0.518±0.103),明显低于模型组(P<0.05),病理切片显示,藏茵陈组小鼠肝脏损伤与模型组比较有所改善。结论 Fas诱导的caspase-3细胞凋亡可能是小鼠冠状病毒性肝炎的致病机制之一,藏茵陈可通过抑制细胞凋亡并改善肝脏损伤程度。     

板蓝根对小鼠实验性肝损伤的保护作用及机制

目的探讨板蓝根对四氯化碳(carbon tetrachloride,CCl4)致小鼠肝损伤的保护作用和机制。方法 2013年1—4月选取健康小鼠40只随机分为生理盐水组(A组)、CCl4组(B组)、低剂量板蓝根组(C组)和高剂量板蓝根组(D组)各10只,A、B两组腹腔注射生理盐水10 ml/kg,1次/d;C组腹腔注射板蓝根剂20 ml/kg,1次/d;D组腹腔注射板蓝根剂80 ml/kg,1次/d,四组均注射10 d。末次给药2 h后,B、C、D三组均腹腔注射1 ml/L的CCl4花生油溶液10 ml/kg建立急性CCl4小鼠肝损伤模型。比较四组小鼠肝脏病理组织学变化、肝匀浆中超氧化物歧化酶(superoxide dismutase,SOD)、丙二醛(malondialdehyde,MDA)水平、血清ALT、AST水平。计量资料采用t检验,P<0.05为差异有统计学意义。结果空泡变性、肝细胞坏死、炎性细胞浸润情况A组分别为0、0、0只,B组分别为8、10、10只,C组分别为7、6、7只,D组分别为5、4、5只。SOD、MDA水平A组分别为(36.24±3.12)U/mg、(5.20±1.93)nmol/mg,B组分别为(19.21±5.67)U/mg、(8.96±2.65)nmol/mg,C组分别为(25.72±4.35)U/mg、(8.65±2.22)nmol/mg,D组分别为(34.61±4.66)U/mg、(5.98±2.15)nmol/mg。A、B两组比较差异均有统计学意义(均P<0.05);C、D两组与B组比较差异均有统计学意义(均P<0.05)。ALT、AST水平A组分别为(39.06±15.42)、(42.34±16.27)U/L,B组分别为(129.46±39.01)、(144.14±30.51)U/L,C组分别为(100.68±29.36)、(106.54±30.36)U/L,D组分别为(74.25±25.87)、(81.73±20.21)U/L。A、B两组比较差异均有统计学意义(均P<0.05);C、D两组ALT、AST的水平与B组比较差异均有统计学意义(均P<0.05)。结论板蓝根对CCl4诱导的急性肝损伤具有明显的保护作用。     

委陵菜酸对小鼠急性肝损伤保护作用

目的观察委陵菜酸(TA)对脂多糖(LPS)/D-半乳糖胺(D-Gal N)诱导的小鼠急性肝损伤的保护作用及其可能机制。方法雄性C57BL/6小鼠90只,随机分为对照组、模型组、阳性对照组及委陵菜酸低、中、高剂量组,各组小鼠分别灌胃给予受试物,连续3 d,末次给予受试物8 h后,除对照组外,其余小鼠腹腔注射LPS/D-Gal N,1.5 h后眼球取血,6 h后处死小鼠,取肝脏,观察肝组织损伤程度;采用试剂盒测定小鼠血清中门冬氨酸氨基转移酶(AST)、谷丙氨酸氨基转移酶(ALT)、总胆红素、肿瘤坏死因子-α(TNF-α)、一氧化氮(NO)、白细胞介素-6(IL-6)和IL-10水平;RT-PCR法检测TNF-α和诱导型一氧化氮合酶(i NOS)基因表达;ELISA法测定NF-κB p65蛋白含量;Western blot法检测细胞色素C和Bcl-2含量;另外,取肝组织匀浆检测caspase-3、8、9活性。结果与对照组比较,模型组小鼠ALT、AST、TNF-α、NO含量[分别为(1 833.5±125.4)、(2 183.5±138.9)U/L、(656.8±64.7)pg/m L、(205.28±16.79)μmol/L]明显升高(P0.05),肝脏中NF-κB p65表达[(228.9±14.2)pg/mg]升高、Bcl-2蛋白表达(0.18±0.03)下降、Caspase-3蛋白表达(275.3±14.7)升高(P0.05);与模型组比较,委陵菜酸3 mg/kg组小鼠血清中ALT、AST、TNF-α、NO含量[分别为(991.3±70.2)、(968.5±68.6)U/L、(226.5±35.9)pg/m L、(133.69±9.79)μmol/L]明显降低(P0.05)、肝脏中NF-κB p65表达[(151.2±6.5)pg/mg]降低、Bcl-2蛋白表达(0.35±0.02)升高、caspase-3蛋白表达(156.3±5.9)下降(P0.05)。结论委陵菜酸可保护LPS/D-Gal N诱导的小鼠急性肝损伤,其机制可能与抑制NF-κB信号通路减轻炎症反应、抑制凋亡蛋白表达、继而减少细胞凋亡有关。     

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.