Subcellular lesions: the current position.

There continues to be an oversimplification of the approach to correlate cellular lesions with radiation induced cell death. Both in the prokaryotic and eukaryotic cell the relationship between vital macromolecules such as DNA, RNA, membrane and proteins is not yet fully understood either in a structural or functional sense. These macromolecules are often closely associated and interdependent. In spite of these recognised relationships much work is still devoted to measuring relatively early changes induced only in the DNA molecule. However, at the present time the quaternary structure of DNA and its closely neighbouring macromolecules is becoming better defined, and disturbances in these vital interrelationships may prove to be the most important radiation lesions. In the attempts to relate identifiable radiation damage to cell malfunction several criteria must be applied. For instance, the measured lesions must exhibit sensitization, protection and shoulder changes in response to the variety of agents and conditions which produce these phenomena at cellular level. In addition the radiation doses employed to produce measurable change must be within the same dose range as those used to study cellular and tissue effects. In much of the published work these criteria have not been applied.