Fig. 3. H₂O₂-induced DNA base damage of human skin fibroblasts from non-AD and AD patients. DNA damage was evaluated immunocytochemically using a specific antibody against 8OH-dG. A shows representative images of non-AD (1,3) and AD (2,4) fibroblasts in basal conditions (1,2) and 2 hours after H₂O₂ treatment (3,4). B shows quantitative analysis of 8OH-dG-positive cells in six non-AD and six AD samples. Bars represent basal (open) and experimental (gray) values and are expressed as a percentage of positive cells per field. Values are the mean±s.e.m. of the results from at least six different fields for each sample. ^*P<0.01 versus the corresponding basal values.