X-ray-induced DNA double-strand breaks as lethal lesions in diploid human fibroblasts compared to Chinese hamster ovary cells.

Calibration of the non-denaturing (pH 9.6) filter elution technique by 125I decays has been used to examine the relationship between X-ray-induced DNA double-strand breaks (dsb) and cellular survival of CHO cells and human fibroblasts. DNA dsb induction varies markedly between the two cell lines, reflecting the different survival levels. The relationships between lethal lesions (-ln S) and DNA dsb are also significantly different for CHO cells and human fibroblasts, suggesting either different probabilities of dsb conversion into lethal lesions or different repair capacities.