Potentially Cytotoxic Lesions

FIGURE 4. Percentage survival of the colony-forming ability of strains of diploid human fibroblasts as a function of the dose of UV radiation given. See Section 2.2 for details on determining UV cytotoxicity. Taken from Maher et ai with permission. 

FIGURE 5. Biological recovery of normal fibroblasts (NF) and lack of recovery of XP12BE cells from the cytotoxic effect of UV radiation. Cells were grown to confluence as described, irradiated with the designated doses of UV, released immediately, and assayed for survival (O, A) or held 7 days in the absence of cell replication (0.5% turnover per 24 hr) and then assayed for survival (, A). Unirradiated control cells were similarly treated and assayed. (O, ) NF (A, A) XP. 

Simonshas recently demonstrated a similar biological recovery of XP cells from group D from 9 to 40% in 24 hr. However, Weichselbaum et 

FIGURE 6. Comparison of the cytotoxicity (loss of cloning ability) produced in different strains of human fibroblasts by exposure to iV-acetoxy-2-acetylaminofluorene (V-AcO-AAF), benzo[a]pyrene 4,5-oxide (BP 4,5-oxide), or 7,12-dimethylbenz[a]anthracene 5,6-oxide (DMBA 5,6-oxide). The procedures used are described in Section 2.2. 

---

Evidence That Excision Repair Can Eliminate Potentially Cytotoxic and Mutagenic Lesions From DNA... 

---