Differential effect of sodium arsenite during the activation of human CD4+ and CD8+ T lymphocytes

Contamination of water with arsenic is a problem affecting several regions of the world. Peripheral blood mononuclear cells (PBMC) from chronically exposed individuals show a lower replicating activity than non-exposed individuals when stimulated with phytohemagglutinin (PHA). We have previously reported that PBMC from healthy donors treated in vitro with 1 muM sodium arsenite (NaAsO2) and stimulated with PHA showed a reduction in proliferation by a delay in cell cycle entry and a decrease in the rounds of cell division. In this paper we tested the effect of 1-5 muM NaAsO2 on the proliferation, viability, blast transformation, expression of the CD4 and CD8 molecules, and during the activation and proliferation of both CD4+ and CD8+ T lymphocytes. We found a reduction in cell proliferation and an increase in non-dividing cells with higher concentrations of NaAsO2 (2-5 microM) when proliferation was studied by 5,6-carboxyfluorescein diacetate succinimidyl ester (CFSE) dilution. The use of 7-aminoactinomycin D (7-AAD) in CFSE-labeled cells allowed us to detect an increase in percentage of non-dividing cells, and an increase in apoptotic/dead cells mainly in non-proliferating cells. Analysis of the expression of CD4 and CD8 molecules on these cells showed that concentrations > or = 2 microM NaAsO2 reduced the expression of the CD8 molecule and induced apoptosis/death in CD4+ cells. Analysis of blast transformation by flow cytometry showed an accumulation of CD8+ resting cells in the presence of NaAsO2. Analysis of CD25 and CD69 expression in kinetics experiments in both subtypes showed a delay in the expression of CD25 and a delay in the downregulation of the CD69 molecule, in both CD4+ and CD8+ cells. However, in the case of CD8+ cells, we detected an accumulation of a CD25- CD69- population in the presence of increasing concentrations of NaAsO2. Altogether, our results show that NaAsO2 alters the expression kinetics of the early activation molecules CD25 and CD69 similarly in both subtypes. In addition, activated and non-activated CD4+ cells die by apoptotic mechanisms and although a percentage of CD8+ cells also die by apoptosis, a subpopulation of these cells is unable to activate and thus accumulates as resting cells.     

Risk of leukemia in relation to exposure to ambient air toxics in pregnancy and early childhood

There are few established causes of leukemia, the most common type of cancer in children. Studies in adults suggest a role for specific environmental agents, but little is known about any effect from exposures in pregnancy to toxics in ambient air. In our case–control study, we ascertained 69 cases of acute lymphoblastic leukemia (ALL) and 46 cases of acute myeloid leukemia (AML) from California Cancer Registry records of children <age 6, and 19,209 controls from California birth records within 2 km (1.3 miles) (ALL) and 6 km (3.8 miles) (AML) of an air toxics monitoring station between 1990 and 2007. Information on air toxics exposures was taken from community air monitors. We used logistic regression to estimate the risk of leukemia associated with one interquartile range increase in air toxic exposure. Risk of ALL was elevated with 3^rd trimester exposure to polycyclic aromatic hydrocarbons (OR = 1.16, 95% CI 1.04, 1.29), arsenic (OR = 1.33, 95% CI 1.02, 1.73), benzene (OR = 1.50, 95% CI 1.08, 2.09), and three other toxics related to fuel combustion. Risk of AML was increased with 3rd trimester exposure to chloroform (OR = 1.30, 95% CI 1.00, 1.69), benzene (1.75, 95% CI 1.04, 2.93), and two other traffic-related toxics. During the child's first year, exposure to butadiene, ortho-xylene, and toluene increased risk for AML and exposure to selenium increased risk for ALL. Benzene is an established cause of leukemia in adults; this study supports that ambient exposures to this and other chemicals in pregnancy and early life may also increase leukemia risk in children.     

Arsenic in drinking water and congenital heart anomalies in Hungary

Inorganic arsenic can get easily through the placenta however there are very few human data on congenital anomalies related to arsenic exposure. Objective of our study was to explore the associations between arsenic content of drinking water and prevalence of some congenital anomalies. Four anomalies reported to the Hungarian Congenital Anomalies Registry between 1987 and 2003 were chosen to be analysed in relation to arsenic exposure: congenital anomalies of the circulatory system (n = 9734) were considered as cases, while Down syndrome, club foot and multiple congenital malformations were used as controls (n = 5880). Arsenic exposure of the mothers during pregnancy was estimated by using archive measurement data for each year and for each settlement where the mothers lived. Analysis of the associations between the prevalence of congenital heart anomalies and arsenic exposure during pregnancy was performed by logistic regression. The child's gender and age of the mother were adjusted for. The associations were evaluated by using the present EU health limit value of 10.0 μg/L arsenic concentration as a cut-off point. Regular consumption of drinking water with arsenic concentration above 10 μg/L during pregnancy was associated with an increased risk of congenital heart anomalies in general (adjusted OR = 1.41; 95% C.I.: 1.28–1.56), and especially that of ductus Botalli persistens (adjusted OR = 1.81, 95%C.I.: 1.54–2.11) and atrial septal defect (adjusted OR = 1.79; 95%C.I.: 1.59–2.01). The presented results showed an increased risk of congenital heart anomalies among infants whose mothers were exposed to drinking water with arsenic content above 10 μg/L during pregnancy. Further studies of possible similar effects of concentrations below 10 μg/L are warranted.     

Maternal arsenic exposure and birth outcomes: A comprehensive review of the epidemiologic literature focused on drinking water

Inorganic arsenic (iAs) is a human toxicant to which populations may be exposed through consumption of geogenically contaminated groundwater. A growing body of experimental literature corroborates the reproductive toxicity of iAs; however, the results of human studies are inconsistent. Therefore, we conducted a comprehensive review of epidemiologic studies focused on drinking water iAs exposure and birth outcomes to assess the evidence for causality and to make recommendations for future study. We reviewed 18 English language papers assessing birth weight, gestational age, and birth size. Thirteen of the studies were conducted among populations with frequent exposure to high-level groundwater iAs contamination (>10 μg/L) and five studies were conducted in areas without recognized contamination. Most studies comprised small samples and used cross-sectional designs, often with ecologic exposure assessment strategies, although several large prospective investigations and studies with individual-level measurements were also reported. We conclude that: (1) the epidemiologic evidence for an increased risk of low birth weight (<2500 g) is insufficient, although there exists limited evidence for birth weight decreases; (2) the evidence for increased preterm delivery is insufficient; and, (3) there exists minimal evidence for decreased birth size. In further investigation of birth weight and size, we recommend incorporation of individual susceptibility measures using appropriate biomarkers, with collection timed to windows of vulnerability and speciated arsenic analysis, as well as consideration of populations exposed primarily to drinking water iAs contamination <10 μg/L. Given the large potential public health impact, additional, high quality epidemiologic studies are necessary to more definitively assess the risk.     

2014年广东省居民重点食品中金属污染物的健康风险评估

目的 了解广东省居民食品中金属污染物的含量及健康风险.方法 采用中国总膳食研究方法,运用2014年广东省重金属污染监测工作所采集的居民食用的大米(n=899)和蔬菜(n=879)中的铅、镉、砷、汞检测数据,评估居民膳食中铅、镉、砷、汞的暴露情况.计算居民铅的暴露边界比、镉的每月摄入量和砷、汞的每周摄入量,并进行健康风险评估.结果 广东省大米和蔬菜中铅、镉、砷、汞总体超标率分别为0.7％,6.5％,0.4％和1.9％,除了大米中镉超标率最高(11.2％)以外,其余元素在大米、蔬菜中含量的超标率都处于较低水平.广东省人群铅的暴露边界比为10.1～80.5;镉的每月摄入量为0.27～19.0 μg/kg,占镉暂定每月可耐受摄入量的1.1％～76％,砷、汞的每周摄入量为0.31～4.19 μg/kg和0.031～0.083 μg/kg,分别占暂定每周可耐受摄入量的2.1％～27.9％和0.8％～2.1％.结论 广东省大米、蔬菜中铅、镉、砷、汞的含量及人群摄入总体处于安全水平;而大米镉的污染不容乐观且有地域性差异,人群食用大米的镉暴露潜在一定的风险,以粤中北部地区为甚.     

环境砷暴露对机体损伤的研究进展

砷及其化合物是国际癌症研究机构确认的人类致癌物。砷的广泛分布及其对机体造成许多不良影响,使得砷中毒已然成为全球性公共卫生问题。笔者综述了长期砷暴露引起机体多系统的严重损害,可造成肝脏、肾脏、肺脏、皮肤、神经系统及免疫系统的相关疾病甚至癌症,并对研究长期砷暴露对机体损伤的机制进行了展望。     

砷铈催化分光光度法测定尿碘的实验室内质量控制

目的建立砷铈催化分光光度法测定尿中碘的实验室内质量控制体系。方法通过试验确定砷铈催化分光光度法测定尿中碘方法的精密度、准确度和检出限,绘制碘测定的均数质量控制图。结果该方法的标准曲线范围碘质量浓度为0～300μg/L,标准曲线的相关系数｜r｜=0．9998,检出限3μg／L,加标回收率为92．4％～106．2％,相对标准偏差0．65％～1．43％。结论实验室内质量控制体系的建立,保证了砷铈催化分光光度法测定尿中碘的结果准确可靠。     

JNK1/2信号通路在砷致细胞凋亡中双向效应的Meta分析

目的 通过Meta分析探讨在砷在诱导细胞凋亡过程中JNK1/2信号通路发挥的作用及机制。 方法 在CNKI、维普、万方、SinoMed、PubMed、Web of Science、Cochrane、Spinger等数据库中检索文献。采用STAIR清单对文献质量进行评价,应用Stata 12.0和RevMan 5.3软件提取数据及分析;以标准化均数差(SMD)来描述其组间差别。 结果 本研究共纳入33篇文献。砷干预组Bax:SMD=9.41,95%CI(1.92,16.90),凋亡细胞:SMD=10.46,95%CI(6.87,14.05),Caspase-3:SMD=8.82,95%CI(0.79,16.85),Cytochrome C:SMD=90.24,95%CI(34.45,146.03),c-jun:SMD=81.66,95%CI(14.38,148.94)和P-JNK:SMD=139.06,95%CI(29.14,248.98)水平均高于对照组。Bcl-2:SMD=-3.78,95%CI(-7.17,-0.39)和PARP:SMD=-6.48,95%CI(-12.89,-0.07)的水平均低于对照组。亚组分析表明正常细胞中高剂量(＞5μmol)且长时间(≥24h)砷暴露可抑制JNK1和JNK2的蛋白表达,在癌细胞中低剂量(≤5μmol)且短时间(＜24h)砷暴露则会诱导JNK1和JNK2的表达。 结论 砷通过介导JNK1/2信号通路诱导细胞凋亡,且作用效果与细胞类型、作用时间和剂量有关。     

Changes in serum thioredoxin among individuals chronically exposed to arsenic in drinking water

It is well known that oxidative damage plays a key role in the development of chronic arsenicosis. There is a complex set of mechanisms of redox cycling in vivo to protect cells from the damage. In this study, we examined the differences in the levels of serum thioredoxin1 (TRX1) among individuals exposed to different levels of arsenic in drinking water and detected early biomarkers of arsenic poisoning before the appearance of skin lesions. A total of 157 subjects from endemic regions of China were selected and divided into arsenicosis group with skin lesions (total intake of arsenic: 8.68-45.71 mg-year) and non-arsenicosis group without skin lesions, which further divided into low (0.00-1.06 mg-year), medium (1.37-3.55 mg-year), and high (4.26-48.13 mg-year) arsenic exposure groups. Concentrations of serum TRX1 were analyzed by an ELISA method. Levels of water arsenic and urinary speciated arsenics, including inorganic arsenic (iAs), monomethylated arsenic (MMA), and dimethylated arsenic (DMA), were determined by hydride generation atomic absorption spectrometry. Our results showed that the levels of serum TRX1 in arsenicosis patients were significantly higher than that of the subjects who were chronically exposed to arsenic, but without skin lesions. A positive correlation was seen between the levels of serum TRX1 and the total water arsenic intake or the levels of urinary arsenic species. The results of this study indicate that arsenic exposure could significantly change the levels of human serum TRX1, which can be detected before arsenic-specific dermatological symptoms occur. This study provides further evidence on revealing the mechanism of arsenic toxicity.     

Influence of MRP1 G1666A and GSTP1 Ile105Val genetic variants on the urinary and blood arsenic levels of Turkish smelter workers

To understand the cellular mechanisms responsible for arsenic metabolism and transport pathways plays a fundamental role in order to prevent the arsenic-induced toxicity. The effect of MRP1 G1666A and GSTP1 Ile105Val polymorphisms on blood and urinary arsenic levels were determined in 95 Turkish smelter workers. Blood and urinary arsenic concentrations were measured by GF-AAS with Zeeman correction and gene polymorphisms were investigated by PCR-RFLP method. The mean blood and urinary arsenic levels were 21.60 ± 12.28 μg/L and 5.58 ± 4.37 μg/L, respectively. A significant association between MRP1 1666A allele and urinary arsenic levels was found (p = 0.001). GSTP1 Ile105Val polymorphism was detected not to be associated with either blood or urinary arsenic levels (p = 0.384, p = 0.440, respectively). Significant association was also detected between MRP1A^-/GSTP1Val⁻ genotypes and urinary arsenic levels (p = 0.001). This study suggested that MRP1 G1666A alone and, also, combined with GSTP1 Ile105Val were associated with inter-individual variations in urinary arsenic levels, but not with blood arsenic levels.