| Comments |
P.7915 middle column bottom paragraph: "Animals have numerous antioxidant defenses, but since these defenses are not perfect, some DNA is oxidized. Oxidatively damaged DNA is repaired by enzymes that excise the lesions, which are then excreted in the urine. Methods have been developed to assay several of these excised damaged bases in the urine of rodents and humans (refs 1, 16), almost all of which appear as the free base from repair by glycosylases. [Investigators] estimate that the number of oxidative hits to DNA per cell per day is about 100,000 in the rat and about 10,000 in the human. DNA-repair enzymes efficiently remove most, but not all, of the lesions formed (ref 4)." |