The comet assay is a popular assay in biomonitoring studies. DNA strand breaks (or unspecific DNA lesions) are measured using the standard comet assay. Oxidative stress-generated DNA lesions can be measured by employing DNA repair enzymes to recognise oxidatively damaged DNA. Unfortunately, there has been a tendency to fail to report results from assay controls (or maybe even not to employ assay controls). We believe this might have been due to uncertainty as to what really constitutes a positive control. It should go without saying that a biomonitoring study cannot have a positive control group as it is unethical to expose healthy humans to DNA damaging (and thus potentially carcinogenic) agents. However, it is possible to include assay controls in the analysis (here meant as a cryopreserved sample of cells i.e. included in each experiment as a reference sample). In the present report we tested potassium bromate (KBrO₃) as a positive comet assay control for the formamidopyrimidine DNA glycosylase (Fpg)-modified comet assay. Ten laboratories used the same procedure for treatment of monocytic THP-1 cells with KBrO₃ (0.5, 1.5 and 4.5 mM for 1 h at 37°C) and subsequent cryopreservation. Results from one laboratory were excluded in the statistical analysis because of technical issues in the Fpg-modified comet assay. All other laboratories found a concentration–response relationship in cryopreserved samples (regression coefficients from 0.80 to 0.98), although with different slopes ranging from 1.25 to 11.9 Fpg-sensitive sites (%DNA in tail) per 1 mM KBrO₃. Our results demonstrate that KBrO₃ is a suitable positive comet assay control.

中文翻译：

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溴酸钾作为Fpg修饰彗星测定的阳性测定对照。

彗星试验是生物监测研究中的一种流行方法。使用标准彗星测定法测量DNA链断裂（或非特异性DNA损伤）。氧化应激产生的DNA损伤可通过使用DNA修复酶识别氧化损伤的DNA来测量。不幸的是，有一种趋势是无法报告测定对照的结果（甚至可能不采用测定对照）。我们认为，这可能是由于不确定什么真正构成了积极控制。毋庸置疑，生物监测研究不能有一个阳性对照组，因为将健康的人类暴露于DNA破坏（因而具有潜在致癌性）的行为是不道德的。但是，有可能在分析中包括化验对照（此处指的是冷冻保存的细胞样品，即 包括在每个实验中作为参考样本）。在本报告中，我们测试了溴酸钾（KBrO₃）作为阳性彗星试验的对照，用于甲酰胺嘧啶DNA糖基化酶（Fpg）修饰的彗星试验。十个实验室使用相同的程序用KBrO ₃（37、0.5、1.5和4.5 mM在37°C下处理1 h）处理单核THP-1细胞，然后进行冷冻保存。由于Fpg修饰的彗星测定中的技术问题，统计分析中排除了一个实验室的结果。所有其他实验室在冷冻保存的样品中发现浓度-响应关系（回归系数从0.80至0.98），尽管每1 mM KBrO _3的斜率范围从1.25至11.9 Fpg敏感位点（尾部％DNA）不等。我们的结果证明KBrO ₃是合适的阳性彗星测定对照。