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diation iniury to many biochemical roads iTi certain kinds of cells might lead con- 

 vereently to damage of certain kinds of vital molecules. What this common de- 

 nominator is in radiosensitive cells is really the core of what we are looking for. 



CARTER: The amplification factor must even go outside of the cell, 

 because Dr. Jones has shown very nicely on many occasions that there is a dis- 

 tant effect; that something is transported from the area of radiation to affect 

 cells in another site. 



KAMEN- Would this be the explanation for why you don't find effects 

 immediately in a given organ that you take out of the carcass after whole-body 

 irradiation? Maybe something is being affected that is sending out that hor- 

 mone and it has to wait. 



KAPLAN: I think some of the remote effects could be due conceivably 

 to release of adrenocortical steroids that do have an inhibitory effect. 



PATT: I think we are getting a little far afield from Dr. Pollard's 

 hypothesis. 



MAZIA- It seems to me that one of the things we should not overlook 

 -- and this applies to Dr. Pollard's calculations -- is that the molecular units 

 we are speaking about are clustered structurally with other units, and the clus- 

 tering is rather important. In the system that Dr. DuBois discussed we are 

 dealing with mitochondria. Suppose, instead of hitting the big molecules that 

 are clustered, you hit the "holes" between them. The "hole" might have a dia- 

 meter 0.01 that of the enzyme molecule. What happens to the enzyme? 



POLLARD: That would be a pretty big hole. 



MAZIA: What would happen? Say that the mitochondrion is the target, 

 and we are, at a given dose level, bombarding the structural cement without 

 damaging directly any of the enzymes. We just blow up the mitochondrion. Isn t 

 this an approach to the amplification Dr. Pollard was speaking about. 



POLLARD- Well, I think it goes back to this question of the charge 

 running around in the molecule. It might run around the whole structure until it 

 came to a particularly sensitive spot, and if that particularly sensitive spot is an 

 enzyme that has very few representatives, then you will have scored a hit pretty 

 easily. 



PLATZMAN: I don't think that this running around should be thought of 

 in terms of such a structure, and I doubt that you intended it that way. 



POLLARD- The point is that if it hits a critical enzyme, it does not 

 have to look around. If it just hits that, it will produce a considerable effect. It 

 is the enzymes that are not critical that are the ones that matter. In fact, it you 

 suppose that of these 900, 000 enzymes many are duplicated and many m a sense, 

 are not essential, then obviously any inactivation of those that have a multiplicity 

 isn't important. Dr. Mazia's point is that if you overlook the ones that are crit- 

 ical, you will probably find peculiar radiation effects. 



MAZIA: The idea is to look upon the mitochondria as an integrated 

 system If you knock out one or a few enzyme units you put the whole structure 

 out of business. Or we can turn to another structure effect. Irradiation can 

 cause rearrangement of parts in a chromosome without at all affecting the qualita- 

 tive character of the DNA. We know that such a rearrangement will have a very 



