Figure 4.

Age-related decline of DNA DSB repair strongly correlates with radiosensitivity. (a) Young and old cells were irradiated with increasing doses of X-ray. Survival was calculated as the relative plating efficiencies of irradiated versus control, unirradiated cells. Logistic regression was performed separately on the 28 samples to estimate the cell's sensitivity to IR. The experiment was performed in triplicate for each sample. (b) Sensitivity of eyelid fibroblasts to X-ray (Gy). The lethal dose that kills 50 and 75% of the population of a test sample's cells were calculated by the logistic regression. (c,d) The MWU test indicates that the young group of cells has a statistically significant higher LD₅₀ and LD₇₅ than that of the old cells. (e) NHEJ efficiency positively correlates with LD₅₀. (f) HR efficiency positively correlates with LD₅₀