Hartmann A, Speit G
Universität Ulm, Abteilung Medizinische Genetik, Germany.
Toxicol Lett. 1997 Feb 7;90(2-3):183-8. doi: 10.1016/s0378-4274(96)03847-7.
We evaluated genotoxic and cytotoxic effects of the three non-mutagenic and non-carcinogenic compounds p-nitrophenol, D-menthol and sodium N-lauroyl sarcosine which have previously been shown to induce DNA double strand breaks (DNA dsb) secondary to induced cytotoxicity. We tested whether genotoxic effects in the alkaline single cell gel test (comet assay) may be confounded by cytotoxicity-induced DNA dsb. Cell viability was determined at the end of the treatment using the fluorescein diacetate/ethidium bromide-assay and plating efficiency was used as an indicator of long-term survivability. Experiments with V79 Chinese hamster cells and human white blood cells revealed negative results in the comet assay despite strong cytotoxic effects. However, cells with extremely fragmented DNA ('clouds') occurred but were excluded from the evaluation under the principle that they represent dead cells. We also noticed a significant loss of cells at cytotoxic concentrations that might be attributed to the induction of highly fragmented DNA which is lost during electrophoresis. Since the comet assay allows the determination of DNA effects on the single cell level, a confounding effect of cytotoxicity on test results can be avoided.
我们评估了三种非诱变且非致癌化合物对硝基苯酚、D-薄荷醇和月桂酰肌氨酸钠的遗传毒性和细胞毒性作用，这些化合物先前已被证明会因诱导细胞毒性而导致DNA双链断裂（DNA dsb）。我们测试了碱性单细胞凝胶试验（彗星试验）中的遗传毒性作用是否可能因细胞毒性诱导的DNA dsb而混淆。在处理结束时使用荧光素二乙酸酯/溴化乙锭试验测定细胞活力，并将接种效率用作长期生存能力的指标。对V79中国仓鼠细胞和人类白细胞进行的实验显示，尽管细胞毒性很强，但彗星试验结果为阴性。然而，出现了具有极度碎片化DNA（“云雾状”）的细胞，但根据它们代表死细胞的原则，在评估中被排除。我们还注意到，在细胞毒性浓度下细胞有显著损失，这可能归因于诱导产生的高度碎片化DNA在电泳过程中丢失。由于彗星试验能够在单细胞水平上测定DNA效应，因此可以避免细胞毒性对测试结果的混淆作用。
