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thing that was noted by Dr. Barron several years ago and it has also been ob- 

 served in our laboratory. We feel confident that, in the case of the spleen, 

 either the enzymes involved in endogenous respiration are inhibited by irradia- 

 tion or radiation produces a deficiency of substrates. 



The endogenous respiration of the spleen is relatively high. When 

 some of the intermediates of the tricarboxylic acid cycle are added to normal 

 spleen slices, one obtains a small stimulation of respiration; radiation does 

 not completely abolish the added respiration. We know from a comparison of 

 the respiration of spleen, kidney and liver slices that no disturbance is pro- 

 duced in kidney and liver with dosages of radiation which produce marked de- 

 creases in the endogenous respiration of spleen. One cannot entirely alleviate 

 this decrease by the addition of intermediates of tricarboxylic acid. 



KAPLAN: What time is this after irradiation and what kind of doses? 



DUBOIS: In the spleen, exposures as low as 100 r cause an appreci- 

 able decrease in endogenous respiration. Dr. Barron used such exposures in 

 his work. Most of our studies have been done with 400 r. The animals were 

 sacrificed at daily intervals for a period of 7 days and then at 10, 14 and 21 

 days. 



PATT: Have you made observations immediately after irradiation? 



DUBOIS: One day is the shortest time interval, but Dr. Barron made 

 observations at 4, IZ and 24 hours and found decreases. 



CARTER: Does not the cellular population change a great deal in this 

 time? 



KAPLAN: I wondered to what extent this is a true chemical change 

 rather than a chemical description of the change in cell population. That is 

 what I was getting at. 



DUBOIS: That question will necessarily come up repeatedly because 

 the biochemical changes and pathological changes follow the same pattern with 

 respect to the time of occurrence. The parallelism of these effects suggests 

 that they are related, but whether the biochemical and pathological changes are 

 related as cause and effect cannot be stated on the basis of any available data. 



BARRON: The only thing is, I doubt there would be any cell change 

 from irradiation. 



CARTER: How long do the lymphocytes live? 



KAPLAN: The lymphocytes are destroyed as early as 3 to 6 hours 

 after irradiation. 



CARTER: The evidence for degeneration actually might be much 

 earlier than that. 



PATT: After 100 r there may be 30 or 40 percent pyknotic lympho- 

 cytes in the lymph nodes within a matter of a few hours. 



POTTER: Still in the tissue? 



PATT: Well, you are working with the intact animal and the situation 



