EFFECTS OF RADIATION ON HACTKRI A 



37' 



1953) which nicely shows the relation between dissolved oxygen at the 

 time of irradiation and survival of X-irradiated E. coli B/r cells. 



Chemical Protection against X rays. Some of the more salient findings 

 in the studies on chemical j)rotecti()n against X rays are illustrated in 

 Table 10-3, adapted from HoUaender and Stapleton (1953), and in the 



20 30 40 



X-RAY DOSE, kr 



Fig. 10-4. Effect of cultural conditions on X-ray sensitivity of cells irradiated in 

 oxygen-saturated buffer. I, aerobic broth cells; II, anaerobic broth cells; III, aerobic 

 glucose cells; IV, anaerobic glucose cells. (HoUaender, Stapleton, and Martin, 1951.) 



following crude classification of compounds so far determined to possess 

 a protective effect: 



1. Sulfhydryl compounds: viz., cysteine, mercaptosuccinate, 2,3-di- 

 mercaptopropanol (BAL), and 2-(2-mercaptoethoxy)-ethanol. 



2. Sodium hydrosulfite (Na2S204). 



3. Alcohols and glycols: viz., methanol, ethanol, isopropanol, pro- 

 panediol, glycerol, triethylene glycol, and propylene glycol. 



4. Metabolic intermediates and products: viz., formate, succinate, 

 pyruvate, fumarate, lactate, and malate. 



In general, a preincubation at 37°C is required for maximum protective 

 effect for the metabolic intermediates and alcohols in low concentration 



