Hoffmann Heike, Högel Josef, Speit Günter
Universität Ulm, Abteilung Humangenetik, Ulm, Germany.
Mutagenesis. 2005 Nov;20(6):455-66. doi: 10.1093/mutage/gei064. Epub 2005 Nov 9.
The comet assay (alkaline single-cell gel electrophoresis, SCG or SCGE) is frequently used in biomonitoring to detect genotoxic effects in humans exposed at the workplace or in their environment. Because of its ready accessibility, blood is most frequently used in such studies. Many studies investigated cigarette smoking either as a genotoxic exposure itself or as a potential confounding factor in occupational studies. However, although smoking is considered to be a relevant exposure towards various genotoxins, conflicting results have been reported in the comet assay studies. The actual reasons for this discrepancy are not known. To further evaluate evidence for smoking-related DNA effects in the comet assay, we now used a meta-analysis approach based on a literature search. We identified 38 studies from 37 publications which were suited for a formal meta-analysis based on the standardized mean difference (SMD) between the study groups. The evaluation of these 38 studies indicated higher levels of DNA damage in smokers than in non-smokers [under a random effects model, SMD = 0.55, 95% confidence interval = (0.16-0.93)]. Subdividing these studies into studies investigating the effect of smoking as a genotoxic exposure (Type A studies, n = 12) and studies investigating smoking as a potential confounder in occupational studies (Type B, n = 26) indicated a significant difference only in Type A studies but not in Type B studies. Furthermore, studies using image analysis or image length measurements (n = 23) only indicated a tendency for a genotoxic effect of smoking, whereas studies using an arbitrary score (n = 15) found a significantly higher level of DNA damage in smokers.
彗星试验（碱性单细胞凝胶电泳，SCG或SCGE）常用于生物监测，以检测在工作场所或环境中接触有害物质的人群的遗传毒性效应。由于血液易于获取，因此在这类研究中最常使用血液样本。许多研究调查了吸烟本身作为一种遗传毒性暴露因素，或作为职业研究中的潜在混杂因素的情况。然而，尽管吸烟被认为是一种与多种基因毒素相关的暴露因素，但在彗星试验研究中却报告了相互矛盾的结果。这种差异的实际原因尚不清楚。为了进一步评估彗星试验中与吸烟相关的DNA效应的证据，我们现在采用基于文献检索的荟萃分析方法。我们从37篇出版物中筛选出38项研究，这些研究适合基于研究组之间的标准化平均差异（SMD）进行正式的荟萃分析。对这38项研究的评估表明，吸烟者的DNA损伤水平高于非吸烟者[在随机效应模型下，SMD = 0.55，95%置信区间 =（0.16 - 0.93）]。将这些研究细分为调查吸烟作为遗传毒性暴露因素的影响的研究（A型研究，n = 12）和调查吸烟作为职业研究中潜在混杂因素的研究（B型研究，n = 26），结果表明仅在A型研究中有显著差异，而在B型研究中没有。此外，使用图像分析或图像长度测量的研究（n = 23）仅显示出吸烟具有遗传毒性效应的趋势，而使用任意评分的研究（n = 15）发现吸烟者的DNA损伤水平显著更高。
