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DISCUSSION 



Stocken: Have you any long-term survival in the mixed treatment, 

 say comparing the thiouronium compound plus bone marrow alone or 

 against the thiouronium compound alone? 



HoUaender: These experiments are going on now and as far as we have 

 gone (these have been going on for about six months), the mice are all 

 alive. This is if one uses isologous bone marrow; I have not discussed 

 the question of homologous or heterologous bone marrow. This is a 

 different problem and I hope that Dr. Lout it will bring some of these 

 questions up. 



Laser: Dr. IIollaender, how do mice react to injection of thiouronium? 

 Do they seem unaffected or are they in a prostrate condition similar to 

 that frequently obtained in mice on application of protective doses of 

 cysteine, which produce pulmonary oedema and a high degree of 

 anaerobiosis ? 



Secondly, I should like to refer to the notation used in your figures 

 where the ordinates are marked "survival." This is generally taken to 

 mean that the graphs indicate the percentage kill. This, however, is by 

 no means the case. Irradiated cells are not dead but appear to be quite 

 normal in many respects. They have, however, lost the ability to form 

 visible colonies within, say, 48-72 hours, although a certain percentage 

 of them may do so at a later period. In view of the importance of your 

 pioneer work, especially on the oxygen effect, for radiobiology in general 

 and lately also in connection with food technology, and in order to avoid 

 confusion in the literature, may I suggest that you substitute "viable 

 count" for "survival". 



One further point: you describe recovery from radiation damage, 

 e.g. on addition of an amino acid. Recovery, to my mind, implies the 

 gradual disappearance of an induced and quantitatively determined 

 inhibition and necessitates the measurement of rates. Have you done so 

 or do you mean recovery to be synonymous with less inhibition ? 



