48 



Journal of Radiology. 



POLLARD: I find that kind of work a little trickly unless you actually 

 determine what it is that the virus has lost. For instance, has the virus simply 

 lost the ability to attach to the host or has it actually lost the ability to multiply 

 or what has happened? Dealing with a virus as an indicator of radiation action 

 has its troubles. 



MAGEE: Bachofer's only test was multiplication. I have often won- 

 dered, whether there is any simple rule-of-thumb way of knowing, in thinking 

 about the various parameters you can use, which are the most sensitive and 

 which are the least so? 



POLLARD: No, there is not. It depends again on the class of inacti- 

 vation. It is almost certain that the indirect effect is on the surface and probab- 

 ly does involve such things as attachment. Possibly, it may even pull the en- 

 velope out so that it releases nucleic acid. That sort of thing may happen but 

 isn't established. The modern feeling on viruses is that they are not molecules, 

 but rather are systems and should be thought of as such. 



TOBIAS: Dr. Barron in his discussion commented chiefly on the role 

 of the -SH group. As I understand, there is a protective agent for the -SH 

 group, P mercaptoethylamine. Would you care to comment on the mode of ac- 

 tion of this substance and on the sensitivity of other groups besides the -SH 

 group? 



BARRON: Yes, I know the work of Bacq. The protective action there 

 is probably due to the reducing power of the mercaptoethylamine. I think it has 

 much more reducing power than glutathione and therefore it is a more reactive 

 agent for the free radicals formed from the irradiation of water. I think all this 

 protective action comes by combination with the free radicals, the competition 

 theory that Dale was talking about. I have tried to do the Swallow experiments 

 with glutathione and DPN, to see whether the radicals of oxidized glutathione do 

 produce the reduction of DPN. Unfortunately, the experiments were negative. 

 I was unable to reduce DPN with glutathione on irradiation. It demonstrates 

 that the potential of the system is too positive to cause the reduction of DPN. 

 All these things depend entirely on the potential of the system. 



PATT: A few things could be added to what Dr. Barron has said, al- 

 though I think we are in general agreement on the interpretation. 



DUBOIS: Dr. Barron, did you mix any of the materials such as oxy- 

 hemoglobin with lactic acid-DPN to study the distribution of the effects between 

 two sensitive systems? 



BARRON: No, the experiments that I have reported were done 10 days 

 ago, after we confirmed Swallow's work. The experiment on the reduction of 

 DPN with propyl alcohol, for instance, was done only yesterday. We are study- 

 ing these experiments, and I know that we are going to try quite a number of en- 

 hancing agents. We intend to try to reduce the cytochrome by this kind of coup- 

 ling action. I became interested in it because I tried to demonstrate that there 

 is formation of free radicals in the oxidation of alcohol. 



TOBIAS: It seemed that the concentration of these agents, for ex- 

 ample, the alcohol, was quite high, probably higher than the occurrence of the 

 same substance in vivo. 



