Influence of Chemicals on Radiosensitivity 123 



The excellent protective ability of cysteamine for Esch, coli 

 and its limitations in animal experiments have stimulated 

 David G. Doherty (Doherty and Burnett, 1955; Doherty and 

 Shapira, 1956) of our laboratory to prepare more than 100 

 derivatives of this compound. Time is too short for a review 



25 



50 75 100 



y-RAY DOSEIkr; 



150 



Fig. 2. Gamma-ray sensitivity of Esch. coli 

 B/r in the presence and absence of cysteamine. 

 0, Yeast extract; O, basal medium; A, cells 

 irradiated in H2O; B, cells irradiated in 

 HgO + • 02 M cysteamine. 



of the functions of all these compounds; therefore, only the 

 results are summarized below: 



1. The protective ability disappears when the number of 

 carbons in the basic structure of AET is increased in excess of 

 3 (Fig. 3). 



