Radiation Effects on Cellular Kinetics

As a result of the advent of autoradiographic technique it is is now possible to study the cell cycle. Little is known about the biochemical process that initiates mitosis and DNA synthesis, and about the mechanism of mitotic delay induced by ionizing radiations. The radiosensitivity of cells in vitro and in vivo varies with the stage of the cell cycle at the time of radiation. The fluctuations in recuperation kinetics after fractionated doses of radiation are explained partly by cell recovery from sublethal damage and partly by cell movement through the cell cycle. The repair process is investigated indirectly by using different agents that are likely to inhibit this process. The effects of radiation on DNA synthesis are described in the light of recent interpretations which indicate indirect rather than direct effects on the biochemical process of DNA synthesis, and are explained in terms of cellular kinetics. (author)