DNA-radicals as structural monitors of direct radiation action: sensitization by incorporation of 5-halouracils.

A survey over the development of studies and the present state of results concerning free radical formation in DNA by sparsely ionizing radiation as studied by electron spin resonance (ESR)-spectroscopy is presented. The emphasis is laid on solid state studies dealing with the determination of the chemical structure of radicals and of radical reactions rather than on quantitative aspects. As a system with close potential relation between model system studies and the in vivo response to radiation the question of radiosensitization of cells by incorporation of 5-halouracil derivatives into their DNA replacing thymine residues is discussed in some detail.