126 Alexander Hollaender and George E. Stapleton 



2. The effect is dose-independent, a true dose-reduction 

 phenomenon (Fig. 5). 



3. The effect is related to inactivation by free radicals. 

 Dose-reduction factor is reduced for oxygen-free suspensions. 



4. The survival of irradiated cells at any temperature may 



10 



-r 



30 

 X-RAY DOSE (kr) 



1 

 70 



Fig. 5. Recovery at various X-ray doses 



(aerobic B/r 20-hour culture cells irradiated). 



O, Holding at 18° C; 0, holding at 37° C. 



(Stapleton, Billen and Hollaender, 1953.) 



be related to the relative rates of synthetic and radiation- 

 induced degradative processes. 



An effect of the medium in which the cells are incubated is 

 displayed at all the temperatures studied (Stapleton, Sbarra, 

 and Hollaender, 1955) (Fig. 6). The pertinent results can be 

 summarized as follows: 



1. Additivity can be shown between the temperature and 



