核黄素缺乏对人成淋巴细胞株遗传稳定性及细胞毒性影响初探

微量营养素(micronutrient)是许多酶的底物或辅酶成分,当其涉及维持基因组稳定性相关的生化反应时,供给状况及代谢特点就可能影响基因组稳定性,构成肿瘤风险因素[1,2]。其缺乏或代谢异常可使基因组稳定性下降,提高肿瘤危险度[4,5]。核黄素(riboflavin,VB2)是黄素腺嘌呤二核苷酸的前体,参与机体生物氧化反应及能量代谢,VB2缺乏可引起亚甲基四氢叶酸还原酶(methylenetetrahydrofolate reductase,MTHFR)的活力降低,引起叶酸代谢异常[6]。当叶酸水平较低或MTHFR活性降低时,通过同型半胱氨酸(homocysteine,HCy)合成S-腺苷甲硫氨酸(S-aden…     

Automation of the in vitro micronucleus and chromosome aberration assay for the assessment of the genotoxicity of the particulate and gas–vapor phase of cigarette smoke

Abstract

Total particulate matter (TPM) and the gas–vapor phase (GVP) of mainstream smoke from the Reference Cigarette 3R4F were assayed in the cytokinesis-block in vitro micronucleus (MN) assay and the in vitro chromosome aberration (CA) assay, both using V79-4 Chinese hamster lung fibroblasts exposed for up to 24?h. The Metafer image analysis platform was adapted resulting in a fully automated evaluation system of the MN assay for the detection, identification and reporting of cells with micronuclei together with the determination of the cytokinesis-block proliferation index (CBPI) to quantify the treatment-related cytotoxicity. In the CA assay, the same platform was used to identify, map and retrieve metaphases for a subsequent CA evaluation by a trained evaluator. In both the assays, TPM and GVP provoked a significant genotoxic effect: up to 6-fold more micronucleated target cells than in the negative control and up to 10-fold increases in aberrant metaphases. Data variability was lower in the automated version of the MN assay than in the non-automated. It can be estimated that two test substances that differ in their genotoxicity by approximately 30% can statistically be distinguished in the automated MN and CA assays. Time savings, based on man hours, due to the automation were approximately 70% in the MN and 25% in the CA assays. The turn-around time of the evaluation phase could be shortened by 35 and 50%, respectively. Although only cigarette smoke-derived test material has been applied, the technical improvements should be of value for other test substances.     

多环芳烃致4种细胞彗星尾矩和双核细胞微核率变化差异的研究

目的探讨彗星尾矩和双核细胞微核(CBMN)率两个指标对多环芳烃反应动力学的差异。方法应用4株细胞系,分别是中国仓鼠卵巢细胞CHO-K1、小鼠成纤维细胞NIH3T3、中国仓鼠肺成纤维细胞CHL、人胚肺成纤维细胞HELF,给予不同浓度的苯并(a)芘[B(a)P]处理,观察彗星尾矩和CBMN率的变化情况。阳性对照分别是过氧化氢和环磷酰胺。结果在所应用的B(a)P浓度范围内,4种细胞均在较低剂量下就出现了明显的拖尾(CHO-K1:0.5μmol/L;NIH3T3:0.75μmol/L;CHL:0.5μmol/L;HELF:0.3125μmol/L),并且随作用浓度的增加,彗星尾矩呈直线形上升趋势,各组与其邻近的较低剂量组相比,差异有显著性。CBMN率在中剂量组才出现显著升高(CHO-K1:2.0μmol/L;NIH3T3:1.5μmol/L;CHL:2.0μmol/L;HELF:1.25μmol/L),达到一定作用剂量后,CBMN率的上升趋于平缓,其剂量反应曲线基本呈S型。结论彗星尾矩和CBMN率对多环芳烃动力学反应模式不同,敏感性不同,在进行环境致癌物早期效应标志物研究时,应合理地将两种方法相结合,综合评价化学物所致遗传损伤。     

氯乙烯暴露对作业工人染色体的损伤

目的 探讨在我国目前职业卫生标准条件下,接触氯乙烯(VCM)能否对作业工人染色体造成损伤. 方法 选择上海某化工厂205名VCM作业工人为接触组,并以41名不接触VCM的健康志愿者为对照组;胞质分裂阻滞微核试验分析两组工人外周血淋巴细胞微核率.因素分析采用广义线性模型中的Poisson回归分析. 结果 VCM接触组工人和对照组人群外周血淋巴细胞微核率分别为(3.58±2.33)‰和(1.22±1.19)‰.Poisson回归分析VCM暴露与微核率之间的关系,最后进入方程的变量为VCM暴露、性别和年龄.在控制潜在的混杂因素如性别、年龄、吸烟和饮酒后VCM暴露的校正FR值及95%CI为3.104 3(2.352 3,4.194 6).以男性作为参比,女性FR值为1.182 3,95%CI为(1.024 9,1.362 5).年龄作为连续变量FR值为1.016 4,95%CI为(1.006 4,1.026 4). 结论 在当前我国职业卫生标准情况下,VCM暴露仍能够对作业工人遗传物质造成损害.     

焦炉作业工人芳烃受体单核苷酸多态性及其单体型与染色体损伤的关系

目的研究芳烃受体(AHR)基因多态性与焦炉作业工人外周血淋巴细胞染色体损伤易感性的关系。方法选取89名焦炉作业工人(暴露组)和60名无职业性多环芳烃及射线暴露的工人(对照组)为研究对象。测定尿中1-羟基芘反映多环芳烃暴露内剂量,用双核淋巴细胞微核评价个体外周血淋巴细胞染色体损伤,采用聚合酶链反应-限制性片段长度多态性方法分析AHR基因rs6960165及rs2282885位点多态性,利用PHASE2.1软件经Bayesian法计算单体型。用协方差统计方法分析不同基因型及单体型对与染色体损伤水平的关系。结果暴露组尿1-羟基芘水平显著高于对照组(P<0.01),暴露组外周血淋巴细胞微核率显著高于对照组(P<0.01)。在校正年龄和自然对数转换后的1-羟基芘后,暴露组AHR基因rs6960165位点多态性与微核率有关联(P=0.014),未发现对照组AHR基因rs6960165位点多态性与微核率有关联(P=0.586);未发现暴露组和对照组的AHR基因rs2282885位点多态性与微核率有关联(P=0.308和P=0.415)暴露组AHR基因不同单体型对与微核率有关联(P=0.007),未发现对照组AHR基因不同单体型对与微核率有关联(P=0.768)。结论AHR基因rs6960165位点多态性及AHR基因单体型是影响焦炉作业工人外周血淋巴细胞染色体损伤水平易感性的可能因素之一。     

Effects of orally administered antioxidants on micronuclei and sister chromatid exchange frequency in workers professionally exposed to antineoplastic agents

The widespread use of antineoplastic drugs in cancer treatment increased concern about possible hazard to workers involved in the preparation and administration of these drugs. In the present study, the effects of commercial antioxidative drug Oligogal Se® on genome protection were analyzed in 15 nurses handling the antineoplastic drugs at the Oncology Department in comparison to twenty healthy volunteers. The nurses took antioxidant mixture Oligogal Se®, consisting of vitamins C, E, A and selenium, one capsule per day, over a period of 6 months. Genome damage was measured in peripheral blood lymphocytes by usage of sister chromatid exchange test and the cytokinesis-block micronuclei test. The frequency of sister chromatid exchange (SCE) and micronuclei (MN) in the exposed group was significantly higher when compared to the control group (SCE, p < 0.05; MN, p < 0.01 respectively). After antioxidant supplementation, the frequency of sister chromatid exchange and micronuclei decreased (p < 0.05) when compared with the values from the beginning of the study, but were still above the values of the control group. The effects of confounding factors such as cigarette smoking and cytostatics exposure time were also evaluated. The data indicated that Oligogal Se® contributed to the decreasing of genome damages in workers handling the cytostatics.     

Cytogenetic effects of vincristine sulfate and ethylene dibromide in human peripheral lymphocytes: micronucleus analysis.

Micronuclei kinetics and persistence in mononucleated and binucleated human peripheral lymphocytes following short-term (4 hr) and continuous (until harvest) in vitro exposure to vincristine sulfate (VS) and ethylene dibromide (EDB) were studied. Lymphocytes were exposed to chemicals for various doses and harvested at different culture times. Micronucleus frequencies were scored in both mononucleated and binucleated cells on the same slide. VS-treated cells showed a significantly higher incidence of micronucleus in both mononucleated and binucleated cells than controls (P less than 0.01). The cells treated continuously with VS produced comparatively higher frequencies of micronucleated cells than those treated for 4 hr. Highest micronuclei frequencies were observed 24 hr after chemical treatment in both mononucleated and binucleated cells and decreased later with time. However, the micronucleus frequencies remained significantly higher than the controls even in the cells harvested at 144 hr. VS induced a large number of micronucleated cells with multiple micronuclei. VS also caused a severe decrease in nuclear division due to cytotoxic effect. Lymphocytes treated with EDB for 4 hr and continuously showed a statistically higher incidence of micronuclei in binucleated cells compared to the controls (P less than 0.05), whereas in mononucleated cells higher micronucleus frequencies were observed only in cultures treated continuously. Continuous presence of EDB induced both dose- and time-dependent increase of micronuclei in both mono- and binucleated cells (P less than 0.05). EDB induced relatively few multiple micronucleated cells in comparison with VS. EDB did not affect nuclear divisions even with continuous treatment. High micronucleus frequencies observed at 144 hr harvest following 4 hr treatment of both EDB and VS suggest the persistence of DNA damage in cells. These studies suggest that micronuclei kinetics in human peripheral lymphocytes depends on the genotoxic potentially and cytotoxicity of a genotoxicant.     

6MVX射线超高剂量照射人离体血淋巴细胞微核的剂量效应研究

本文用CB微核法研究了超高剂量6MVX射线照射人离体血后微核(MN)的剂量效应关系, 见到剂量高至25Gy仍可见双核cB细胞, 在0～10Gy范围内, MN率与照射剂量呈正相关 关系, 并得到拟合较好的回归方程, 有可能打破近30正来生物剂量估算为5 Gy的上限, 使能直接的估算大于5Gy受照者的生物剂量, 摄高了以MN检测作为生物学剂量计的应用价值。10Gy以上, MN串的上升呈平缓的坪趋势, 在10～25Gy范围内虽不能精确的估算剂量, 但片中双核CB细胞的多少, 对判断剂量有—定参考价值。     

Assessment of oxidative stress responses and the cytotoxic and genotoxic potential of the herbicide tembotrione in HepG2 cells

Tembotrione is a triketone herbicide, usually used for post-emergence weed control in corn. Currently, there is little or no published data on its genotoxicity to human cells either in vitro or in vivo. This study evaluated the impact of acute (4 and 24 h) exposure to low concentrations of tembotrione [corresponding to the acceptable daily intake (0.17 μg/mL), residential exposure level (0.002 μg/mL) and acceptable operator exposure level (0.0012 μg/mL)] on human hepatocellular carcinoma cell line HepG2, using biomarkers of oxidative stress, CCK-8 colorimetric assay for cell viability, alkaline comet assay, and cytokinesis-block micronucleus “cytome” assay. Tembotrione applied at concentrations likely to be encountered in occupational and residential exposures induced cytogenetic outcomes in non-target cells despite non-significant changes in the values of oxidative stress biomarkers. We assume that the observed effects were mainly the consequence of impaired metabolic pathways in HepG2 cells due to the inhibition of the enzyme 4-hydroxyphenyl-pyruvate-dioxygenase by tembotrione, which possibly caused a depletion of folate levels leading to excess formation of nuclear buds in the affected cells. Regardless of the fact that tembotrione was previously reported negative for mutations and chromosome aberrations in vitro, our findings call for more precaution in its use.