Complexity of Damage Produced by Ionizing Radiation

Traditional studies of the effects of ionizing radiationon mammalian cells have concentrated on the endpointsof cell death, mutagenesis, transformation, and chromosomal aberrations (Hall 1994). It is generally acceptedthat damage to DNA is the cause and that the lesion responsible is the double-strand break (DSB) (Painter1980; Ward et al. 1985). More recently, other effects ofradiation have been observed (often at low doses): apoptosis, gene induction, chromosomal instability, inductionof radioresistance, bystander effects, etc. (summarized inWard 1999). The molecular lesions responsible for theseresponses have not yet been established; however, it isdifficult to conceive for a variety of reasons that damageto DNA is not involved. Hence, an understanding of thefull spectrum of lesions produced by ionizing radiation inDNA would be valuable...