PART III 



USE OF TRACERS IN THE STUDY OF 

 BIOLOGICAL EFFECTS OF RADIATION 



THE MODIFICATION OF X-RAY SENSITIVITY 



BY CHEMICALS* 



ALEXANDER HOLLAENDER, G. E. STAPLETON 

 and W. T. BURNETT, Jr. 



The study of the effects of chemicals on the X-ray sen- 

 sitivity of hving cells has grown out of the finding that the 

 resistance of these cells can be influenced by reducing the 

 oxygen tension in the medium in which the organisms are 

 irradiated. For this reason, we will review the latter field 

 before discussing the protection by chemicals. 



About 30 years ago Holthusen (1921) reported that reduc- 

 tion of the oxygen tension of living cells during exposure to 

 X-rays resulted in a decrease in the sensitivity of the cells. 

 Twelve years later Crabtree and Cramer (1933) again un- 

 covered the phenomenon, and Thoday and Read re-investi- 

 gated the problem about 5 years ago. Since then intensified 

 research has brought out many interesting points and has 

 opened up new avenues for the extensive study of the 

 mechanism of radiation damage. A review of this field, 

 especially in its historical aspects, appeared a short time ago 

 (Bacq, 1951). 



Effect of Oxygen on X-ray Sensitivity 



We would like to discuss work along these lines which is 

 being conducted at the Oak Ridge National Laboratory. The 



♦Work performed under contract W-7405-eng-26 for the Atomic Energy 

 Commission in the Biology Division, Oak Ridge National Laboratory. 



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