番茄红素对丙烯腈染毒大鼠睾丸保护机制的研究

目的研究番茄红素对丙烯腈(ACN)染毒大鼠睾丸的保护性机制。方法将72只雄性SD大鼠随机分成6组,分别为对照组(Control)、染毒组(ACN)、泰特(TAD)组(ACN+TAD),低剂量(10mg/kg)、中剂量(20mg/kg)和高剂量(30mg/kg)番茄红素组。对各组睾丸组织脂质过氧化产物(MDA)、超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)水平进行检测,对睾丸组织病理切片HE染色及NF-κB p65免疫组化染色。结果与对照组比较,染毒组大鼠MDA含量升高,而SOD和GSH活力水平均下降,组织形态明显损伤,NF-κB p65表达升高,差异有统计学意义(P0.05);番茄红素处理以后,特别是中、高剂量番茄红素处理以后,MDA含量明显降低,而SOD、GSH活力水平上升,同时组织形态损伤程度减轻,NF-κB p65的表达降低,差异有统计学意义(P0.05)。结论番茄红素对ACN染毒所致大鼠睾丸损伤有一定的保护作用,且这种保护作用可能与减少氧化应激和降低NF-κB的表达有关。     

矽肺患者氧化应激指标及外周血单核细胞NF-κB水平的变化

目的 观察矽肺患者氧化应激指标及外周血单核细胞NF-κB水平的变化,探讨矽肺发生发展的机制.方法 选择某铸造厂接触矽尘作业工龄在1年以上的工人200例为接尘组,该厂2008年住院及门诊随访的矽肺患者130例为矽肺组,32例0+病例为观察对象组,同时选择某酒店服务人员100例为对照组.分别测定超氧化物歧化酶(SOD)、血清中谷胱甘肽过氧化物酶(GSH-Px)、一氧化氮合酶(NOS)活力,一氧化氮(NO)、丙二醛(MDA)含量及总抗氧化能力(T-AOC),外周血单核细胞核蛋白中NF-κB水平.结果 与对照组比较,接尘组和矽肺组NO含量明显升高,SOD活力明显降低,差异均有统计学意义(P＜0.01).与对照组及接尘组比较,矽肺组T-AOC水平、NOS活力、MDA含量均明显升高,差异均有统计学意义(P＜0.01).与对照组[(223.360±46.838)U/ml]比较,接尘组及矽肺组GSH-Px活力[(231.164±36.484)、(270.469±39.228)U/ml]明显升高,且矽肺组GSH-Px活力明显高于接尘组,差异均有统计学意义(P＜0.05,P＜0.01).与观察对象组[(256.906±21.418)U/ml]和Ⅰ期矽肺组[(259.594±34.790)U/ml]比较,Ⅲ期矽肺组GSH-Px活力[(290.750±39.129)U/ml]明显升高,差异均有统计学意义(P＜0.05).与对照组[(59.71±9.27)ng/L]比较,接尘组及矽肺组NF-κB水平[(72.06±9.12)、(85.25±11.64)ng/L]明显升高,且矽肺组NF-κB水平明显高于接尘组,差异均有统计学意义(P＜0.01).血清中GSH-Px活力与矽肺分期呈正相关(r=0.507,P＜0.01).外周血单核细胞核蛋白NF-κB水平与矽肺分期、年龄、GSH-Px活力、NO含量呈正相关,差异均有统计学意义(r值分别为0.376、0.243、0.233、0.221,P＜0.01).结论 机体氧化和抗氧化系统的失衡与矽肺的发生发展有关,并与NF-κB的活化一致.

Abstract：

Objective To investigate the change of indicators of oxidative stress in serum and NF-κB in peripheral blood mononuclear cells of patients with silicosis, and explore the mechanism of the development of silicosis. Methods The subjects were divided into (1) 200 workers exposed to SiO2 for at least 1 years in a foundry served as the dust-exposure group; (2) 130 cases with silicosis (Ⅰ phase silicosis 64 cases, Ⅱ phase 46 cases Ⅲ phase 20 cases) served as the silicosis goup; (3) 32 cases with 0+ phase silicosis in the foundry served as the observed group,(4)100 subjects from a hotel served as the control group. The serum including superoxide dismutase (SOD), nitric oxide (NO), serum glutathione peroxidase (GSH-Px), total antioxidant capacity (T-AOC), nitric oxide synthase (NOS), lipid malondialdehyde (MDA) and NF-κB protein levels in peripheral blood mononuclear cells were determined, respectively. Results Compared with the control group,NO levels in dust-exposed group and silicosis group significantly increased, and SOD decreased significantly (P＜0.05 or P＜0.01). Compared with the control group and dust-exposed group, T-AOC, NOS, MDA levels in silicosis group significantly increased (P＜0.05 or P＜0.01). GSH-Px in dust-exposed group and silicosis group were (231.164±36.484) and (270.469±39.228)U/md, respectively which were significantly than that [(223.360±46.838) U/ml] in control group (P＜0.05 or P＜0.01), and there was significant difference of GSHPx between the silicosis group and the dust-exposed group significantly (P＜0.01). GSH-Px level [(290.750±39.129) U/ml] in Ⅲ phase silicosis group were significantly higher than those [(256.906±21.41) and (259.594±34.79) U/ml] in observation group and Ⅰ phase silicosis group (P＜0.05). NF-κB levels [(72.06±9.12) and (85.25±11.64) ng/L] in dust-exposed group and silicosis group were significantly higher than that [(59.71±9.27) ng/L] in control group (P＜0.01), and there was significant difference of between the silicosis group and the dust-exposed group (P＜0.01). There was a positive correlation between serum GSH-Px level and the silicosis stages (r=0.507,P＜0.0l). Also there was a positive correlation between NF-κB level and silicosis stages, age, GSH-Px or NO levels (r=0.376, 0.243, 0.233, 0.221, P＜0.01). Conclusion The imbalance of oxidative and anti-oxidation system and the activation of NF-κB are related with the occurrence and development of silicosis. The monitoring of oxidative stress indicators and NF-κB is beneficial to the prediction and prognosis assessment of silicosis.     

氧化应激及核因子-κB在百草枯致大鼠肺损伤中的变化

目的 观察急性百草枯(PQ)中毒大鼠氧化应激及肺组织核因子-κB(NF-κB)的变化,探讨四氢吡咯二硫代氨基甲酸酯(PDTC)的治疗机制.方法 SD大鼠144只随机分为对照组6只、PDTC对照组36只、pQ染毒组56只、PDTC治疗组46只.染毒组和治疗组予生理盐水稀释PQ 80mg/kg一次性灌胃后2 h,治疗组给予PDTC 100 mg/kg一次性腹腔注射,染毒组予等量生理盐水腹腔注射;对照组和PDTC对照组于生理盐水1 ml/kg灌胃后2 h,PDTC对照组予PDTC 100 mg/kg一次性腹腔注射,对照组予等量生理盐水腹腔注射.不同处理后1、3、7、14、25、56 d观察大鼠肺组织病理改变;测定血清中丙二醛(MDA)含量及谷胱甘肽过氧化物酶(GSH-Px)、超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、髓过氧化物酶(MPO)活力;测定肺组织中羟脯氨酸(Hyp)含量及NF-κB p65的表达.结果 与对照组比较,染毒组血清中MDA含量和MPO活力升高,GSH-Px、CAT、SOD活力降低,相应时点差异有统计学意义(P<0.05或P<0.01);肺组织NF-κB活性在1、3、7、14 d明显升高,肺组织Hyp含量在14、28、56d明显升高,差异均有统计学意义(P<0.01).PDTC治疗组血清中MDA含量降低,GSH-Px、CAT、SOD活力升高,与染毒组比较,相应时点差异均有统计学意义(P<0.05或P<0.01),在14 dMPO活力为(119.56±21.23)U/L,明显低于染毒组,差异有统计学意义(P<0.05);与染毒组比较,治疗组在1、3、7 d肺组织中NF-κB活性明显降低,差异有统计学意义(P<0.05或P<0.01);治疗组肺组织中Hyp含量在28、56d分别为(0.89±0.05)、(0.93±0.13)μg/mg,明显低于染毒组,差异有统计学意义(P<0.01);病理检查结果显示,治疗组肺组织炎症及纤维化程度均较轻.结论 氧化应激及NF-κB活化是参与PQ致肺损伤的重要机制;PDTC能纠正氧化还原失衡,抑制NF-κB活化,减轻PQ中毒大鼠的肺损伤.     

熊果酸对矽肺大鼠肺泡巨噬细胞数量和波形蛋白表达的影响

目的研究熊果酸对矽肺大鼠肺泡巨噬细胞(AM)数量和波形蛋白表达的影响。方法将无特定病原体级Wistar大鼠随机分为空白对照组、溶剂对照组、矽肺组和熊果酸组,每组20只。空白对照组大鼠不予任何处理,其余3组大鼠均通过非暴露式气管滴注法一次性予剂量为250 mg/kg体质量的游离二氧化硅混悬液。其后,空白对照组和矽肺组大鼠灌胃剂量为10 m L/kg体质量的0. 9%氯化钠溶液,溶剂对照组大鼠灌胃10 m L/kg体质量为0. 6%的羧甲基纤维素钠溶液,熊果酸组大鼠灌胃剂量为40 mg/kg体质量的熊果酸,1次/d,连续56 d。在灌胃第7、14、28、56天时各组分别处死5只大鼠,收集支气管肺泡灌洗液(BALF)检测AM数量,采用免疫组织化学法和免疫印迹法检测肺组织中波形蛋白的表达。结果溶剂对照组和矽肺组大鼠4个时间点BALF中AM数量和肺组织中波形蛋白相对表达水平均高于同时间点空白对照组(P 0. 05)。熊果酸组大鼠BALF中AM数量在4个时间点分别低于同时间点溶剂对照组和矽肺组(P 0. 05),在第7和14天均高于同时间点空白对照组(P 0. 05),但在第28和56天分别与对照组比较,差异均无统计学意义(P 0. 05)。熊果酸组大鼠4个时间点肺组织中波形蛋白相对表达水平分别低于同时间点溶剂对照组和矽肺组(P 0. 05),高于同时间点空白对照组(P 0. 05)。免疫组织化学法结果显示:建立矽肺模型后,溶剂对照组和矽肺组大鼠肺组织纤维化程度逐渐加重,波形蛋白阳性表达在各时点有不同程度增加;熊果酸组大鼠肺组织中波形蛋白表达趋势与上述2组相似,但肺组织纤维化程度和肺泡结构破坏程度均相对较轻,波形蛋白阳性表达相对减弱。结论熊果酸可减少矽肺大鼠肺泡巨噬细胞的数量,下调波形蛋白的表达。     

侧脑室注射苯并(a)芘对大鼠脑组织形态、NO、iNOS和脂质过氧化的影响

[目的]研究苯并(a)芘[B(a)P]对大鼠脑组织形态、一氧化氮(NO)、诱导型一氧化氮合酶(iNOS)、超氧化物歧化酶(SOD)和丙二醛(MDA)水平的影响,探讨B(a)P的神经毒性作用及机制. [方法]健康雄性SD大鼠40只,按体重编号后随机分为5组,分别为空白对照组(生理盐水)、溶剂对照组(二甲基亚砜)、B(a)P 0.5、5、50mmol/L组,每组8只,侧脑室注射各溶液10μL.1周后,断头处死,取大脑半球.作病理切片,光镜观察大鼠神经细胞变化.应用试剂盒测定脑NO、iNOS、MDA和SOD水平. [结果]病理切片显示,对照组小脑、海马神经细胞基本正常,各剂量组小脑、海马神经细胞病变随苯并(a)芘浓度增大而加重,表现为小脑蒲肯野细胞数目逐步减少,坏死细胞增多;海马神经细胞排列逐渐紊乱,数目逐步减少,坏死细胞增加,高剂量组表现最为典型.各剂量组与对照组比较,大鼠脑组织中NO、iNOS、MDA增高,差异有统计学意义(P<0.05);大鼠脑组织中SOD下降,差异有统计学意义(P<0.05). [结论]B(a)P染毒大鼠脑组织出现了明显病理变化,NO及iNOS的水平升高,SOD活性降低,MDA含量升高.     

短期重复暴露邻苯二甲酸二(2-乙基)己酯对雄性大鼠睾丸脂质过氧化水平的影响

目的探讨邻苯二甲酸二(2-乙基)己酯(DEHP)短期重复暴露对雄性大鼠生殖毒性及睾丸脂质过氧化水平的影响。方法将初断乳清洁级Wistar雄性大鼠40只按体重随机分为DEHP低、中、高剂量组[DEHP的染毒剂量分别为10、100、1 000 mg/(kg.d)]和溶剂对照组(玉米油),每组10只。采用灌胃方式进行染毒,连续染毒30 d。测定睾丸组织中丙二醛(MDA)和还原型谷胱甘肽(GSH)含量、超氧化物歧化酶(SOD)和谷胱甘肽过氧化物酶(GSH-Px)的活力,蛋白定量采用酚试剂法。结果染毒第4周,DEHP高剂量染毒组体重、睾丸质量及其脏器系数低于溶剂对照组,差异均有统计学意义(P<0.05或P<0.01)。DEHP中、高剂量染毒组睾丸组织中MDA含量高于溶剂对照组,差异均有统计学意义(P<0.05),且MDA含量随着DEHP染毒剂量的增加而升高。DEHP高剂量染毒组睾丸组织中GSH含量、SOD和GSH-Px活力低于溶剂对照组,差异有统计学意义(P<0.05),且SOD和GSH-Px活力均随着DEHP染毒剂量的增加而降低。结论DEHP短期重复暴露对初断乳大鼠的生殖系统发育具有明显的毒性作用。DEHP及其代谢产...     

硒对氟致大鼠肝脏损伤的保护作用

目的探讨硒对氟致大鼠肝脏损伤的保护作用,探寻硒的最佳作用剂量及可能的作用靶点。方法将240只健康初断乳清洁级SD雄性大鼠随机分成8组,分别为溶剂对照(自来水,含氟量0.2 mg/L,含硒量1μg/L)组,氟(50 mg/L)单独染毒组,低(0.375 mg/L)、中(0.75 mg/L)、高(1.5 mg/L)浓度硒单独染毒组和低(0.375 mg/L)、中(0.75 mg/L)、高(1.5 mg/L)浓度硒+氟(50 mg/L)联合染毒组,每组30只。采用自由饮水方式进行染毒,连续染毒6个月。实验期间,大鼠进食标准饲料(氟含量0.2 mg/kg,硒含量为0.1～0.2 mg/kg)。染毒结束后,测定肝脏中谷胱甘肽过氧化物酶(GSH-Px)、总抗氧化能力(T-AOC)、超氧化物歧化酶(SOD)活力及丙二醛(MDA)含量及核转录因子κB(nuclear factor kappa B,NF-κB)表达水平。并观察氟中毒的一般症状和肝脏的病理学损伤。结果氟单独染毒组大鼠氟斑牙症状明显。与溶剂对照组相比,氟单独染毒组大鼠肝脏中GSH-Px、SOD活力降低,MDA含量升高,差异均有统计学意义(P0.05);高浓度硒单独染毒组SOD活力降低,差异均有统计学意义(P0.05)。与氟单独染毒组相比,高浓度硒+氟联合染毒组大鼠肝脏中GSH-Px活力上升,差异均有统计学意义(P0.05);高浓度硒+氟联合染毒组MDA含量下降,差异均有统计学意义(P0.05)。各染毒组大鼠肝脏中T-AOC活力间比较,差异无统计学意义。与溶剂对照组相比,氟单独染毒组和低浓度硒+氟联合染毒组大鼠肝组织中NF-κB表达水平升高,差异均有统计学意义(P0.05)。与氟单独染毒组相比,中浓度硒+氟联合染毒组和高浓度硒+氟联合染毒组大鼠肝组织中NF-κB表达水平有所降低,但差异无统计学意义。病理学结果显示,氟+硒联合染毒组大鼠肝细胞变性坏死程度明显减轻,且肝细胞变性坏死程度随着硒染毒浓度的升高而呈下降趋势。结论 1.5 mg/L是在本实验条件下硒对氟致肝脏损伤的最佳保护作用剂量,NF-κB可能是硒拮抗氟中毒的药物靶点。     

氟中毒大鼠血清中NO和MDA及GSH-Px的研究

[目的]研究不同浓度氟对大鼠血清自由基和氧化应激的影响。[方法]在饮水中加入含NaF(分析纯)10,20,40mg/kg的去离子水灌胃喂饲大鼠3月后,测定尿氟、血清氟含量、血液中的钙浓度。血清中的一氧化氮(NO)、丙二醛(MDA)及谷胱甘肽过氧化物酶(GSH-Px)的含量。[结果]随染氟剂量的增加,3月后各剂量组大鼠尿氟浓度相应增加,存在剂量-效应关系(R=0.914,P﹤0.01),与对照组相比有统计学差异(P﹤0.01);各剂量组血氟浓度相应增加,存在剂量-效应关系(R=0.930,P﹤0.01),与对照组相比有统计学差异(P﹤0.05);各剂量组大鼠血钙浓度相应下降,存在剂量-效应关系(R=-0.899,P﹤0.01),与对照组相比有统计学差异(P﹤0.01);各剂量组NO的含量相应增加,存在剂量-效应关系(R=0.951,P﹤0.01),与对照组相比有统计学差异(P﹤0.01);各剂量组MDA含量升高,存在剂量-效应关系(R=0.923,P﹤0.01),与对照组相比有统计学差异(P﹤0.05);各剂量组GSH-Px的活性下降,存在剂量-效应关系(R=-0.966,P﹤0.01),与对照组相比有统计学差异(P﹤0.05),特别是高氟剂量组NO及MDA的含量最高而GSH-Px的活性最低。[结论]慢性氟中毒可导致大鼠处于氧化应激状态。     

葡萄籽粉对自然衰老大鼠的抗氧化作用研究

目的:研究葡萄籽粉对自然衰老大鼠的抗氧化作用。方法:将48只雄性老龄SD大鼠按其血清丙二醛(MDA)含量分层后随机分为3个剂量组和1个阴性对照组,每组12只大鼠。3个剂量组分别给予200 mg/kg BW、100 mg/kg BW、50 mg/kg BW的葡萄籽粉,阴性对照组给予去离子水,采用经口灌胃法给样,每日1次,连续灌胃90 d。试验终末测定全部大鼠体内MDA、脂褐质(Lip)含量和超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)活性。结果:葡萄籽粉能显著提高老龄大鼠体内的SOD和GSH-Px活性,降低体内MDA含量,对Lip含量无显著影响。结论:葡萄籽粉具有抗氧化功能。     

纳米硫化镉对人肾小管上皮细胞氧化损伤的影响

目的探讨纳米硫化镉(n Cd S)对人肾小管上皮细胞(HKC)氧化损伤的影响及其机制。方法首先应用噻唑蓝(MTT)实验观察暴露于生理盐水(对照组)和不同剂量浓度纳米Cd S(处理组)处于对数生长期的人肾小管波细胞(HKC)存活率的影响。检测细胞内的丙二醛上(MDA)、谷胱甘肽(GSH)、谷胱甘肽过氧化物还原酶(GSH-Px)和超氧化歧化酶(SOD)含量,并采用蛋白质印迹法观察纳米Cd S对细胞的NF-κB蛋白的表达情况。结果随着n Cd S对HKC细胞染毒剂量的增加,细胞存活率逐渐降低(P0.05);细胞内GSH、GSH-Px和SOD含量显著降低(P0.05),MDA、NF-κB蛋白表达量逐渐升高(P0.05)。结论 n Cd S可能通过影响HKC内MDA、GSH、GSH-Px、SOD产生和NF-κB蛋白表达,从而导致HKC抗氧化系统的损伤而发挥氧化损伤作用。     

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.     

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.     

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.     

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.     

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.