GENERAL DISCUSSION 133 



Robert H. Brownson (Medical College of Virginia): To answer the first 

 question, this was total head x-ray. Second, this was a cumulative exposure, and 

 we have not compared the total radiation effect accumulated at one time with it. 

 Concerning the effects of radiation, the alteration was cumulative in the direction 

 of change which was more quantitative than qualitative. The effects we saw did 

 not seem to show more severity in themselves individually, but more intensity 

 through the actual quantity of such change. The total picture which we saw at the 

 end, beginning with 2,000 r as a minimum dose, demonstrated individual changes 

 at 228 days similar to those changes that we could see using the 5,000 r level 

 following a shorter postirradiation. The problem was to have these animals 

 survive. Many did not survive 228 days, probably due to being stressed with an 

 additional nutritional deficiency. In testing these animals psychologically, we had 

 to deprive them of some food, and this influenced the death rate which accelerated 

 with the increasing cumulative radiation. The group which exhibited the greatest 

 change was the 5,000 r cumulative group, which were not subject to any type of 

 psychologic testing and went through a relatively normal span of 228 days. Much 

 of the probelm in correlating the changes of one of the animals with 18-20 r with 

 5,000 r was that these animals had gone through 228 days normally while the 

 5,000 r animals did not survive. Most of the changes were quantitative and in 

 general increased in direct proportion to cumulative dosage and, to a degree, to 

 time after exposure. 



Orville Bailey: In the terms I ordinarily use it seems as the intensity of the 

 radiation goes down, the amount of damage per total dose also falls. One can 

 build up almost grotesque amounts of x-ray dosage without damage if given slowly 

 enough over a long period of time. Most of the lantern slides which Dr. Brownson 

 showed were in the acute phase of the reaction which is difficult to evaluate. The 

 focal neuronal changes that were described seemed like small foci of "dark 

 neurons," the change which Dr. Gammermeyer has studied. They are artifact 

 or at least, reflect some terminal state of activity in that particular cell. Most of 

 the changes in the Purkinje cells, as Dr. Vogel and associates have demonstrated, 

 are quite frequently found in control monkeys. 



E. C. Alvord (University of Washington School of Medicine): I would like 

 to stress one minor theme that was developed by Dr. Rugh and has recurred in 

 rather low notes through most of these papers. This is the concept that the body 

 as a whole is made up of a mosaic of many structures, each of which has vastly 

 different sensitivities to radiation. This concept of a mosaic also applies within 

 a part of the body, namely the nervous system itself. There are a number of 

 syndromes that have been delineated, particularly by Maisin of Belgium, on the 

 basis of survival times following various doses of x-rays to various parts of the 

 body. He speaks of a "delayed head syndrome," which occurs in rats after 1,000 r 

 to the head, the rats dying about 5 months later, and of an "oropharyngeal 

 syndrome," which suddenly appears at 1,500 r and cuts the survival time down to 

 10 days. I would like to ask Dr. Brownson to define the exact site of the irradia- 

 tion to the heads of his rats. I doubt that this included the whole head, since 

 Maisin and others have found it difficult for rats to live beyond 10 days following 

 irradiation of the whole head with 1,500 r or more. This "oropharyngeal syndrome" 

 has been found to be due to the inclusion of the oral pharynx, tongue, and lower 



