344 GENERAL DISCUSSIOX 



referring here only to acute cases. We see cases that present themselves clinically at 

 varying times during life after having received therapeutic radiation involving the kidney 

 regions. They simulate other clinical sjmdromes as far as the kidneys are concerned — 

 benign or maUgnant hjrpertension, acute or clironic nephritis and so on. There are changes 

 m some cases that can be seen early, but the patients may or may not die acutely. We 

 are workmg on localized radiation of the kidneys trying to simulate these chnical con- 

 ditions and we find the same tiling. We do renographic, angiographic, and histopatho- 

 logical studies in animals sacrificed periodically after irradiation to observe the develop- 

 ment of neplu-osclerosis, and whether it presents clinically as an acute or sub-acute case 

 or chronic case depends on the rate of the vascular change. In this regard our observa- 

 tions are in agreement with Luxton's excellent description of human patients with 

 radiation nepliritis. 



cottier: I should like to comment shortly on the possible pathogenesis of small vessel 

 damage in various stages of irradiation. As Dr. Casarett mentioned, one finds a reduction 

 in the number of small blood vessels, wliich we observed also. In addition to that, this is 

 a weU-knoAvn arteriolocapfilary hyalmosis, which is a discontinuous process — ^you find 

 it at specific sites along the vessel between apparently normal parts, and then you find 

 an increased incidence of capillary telangiectasis. Now, we produced by heavy irradiation 

 of the pituitary within 24 hours microthrombi of the sinusoids of the pituitary, and it is 

 interesting to see that in these late changes of arterioles and capillaries the obstructive 

 lesion — the intimal hyahnosis — is also focal in nature, not diffuse, and therefore one has 

 to consider microtlu*ombi formmg on endothelial lesions or on other forms of vessel well 

 lesions to be one, if not the most important, effect. 



beinkjian: In rabbits which have received about 1,000 r the agglutination rate of the 

 corpuscles about two horn's after irradiation is very much increased. This is caused by the 

 release into the circulation of some large macromolecules, and we do not know what they 

 are. But the rate of agglutination is uicreased so much that tliis could well explain the 

 microtlu-ombi. 



Changes in Connective Tissue 



BACQ: I tliink we will now pass on to another point. As far as the circulation within the 

 bone-marrow is concerned we have very httle physiological data indeed. Technically it is 

 very difficult if not impossible to separate in the bone the circulation to the bone-marrow 

 from that of the bone tissue itself. But one may also beUeve that the injury to the vessels 

 is not so much witliin the endotheUum — or some factor in the blood wliich accelerates the 

 possibility of tlu'ombi formation — but withm the elastic tissue of the vessels. This point : 

 the very important changes wliich may be induced immediately after irradiation or a 

 very long time after irradiation in the physiology or biochemistry of the whole connective 

 tissue has been already discussed j'esterday. One must remember a few tilings — first 

 that the biochemistry of this tissue — the rate of renewal of the molecules — is very 

 tightly controlled by the neuro-endocrine system, mainly the pituitary and the adrenal 

 cortex. On the other hand, there is one tissue which is very peculiar. It's the brain, where 

 one hasn't got any connective tissue; the connective tissue is replaced by glial cells which 

 apparently are quite sensitive to irradiation accordmg to some work done by Gerebtzoflf 

 in Liege. It seems that one doesn't know enough about what happens a long time after 

 irradiation, about the delayed biochemical effects on these connective tissues, on the 

 macromolecules and especially the mucopolysaccharides which play such an important 

 role. I thought that just to start the discussion, it might be a useful research project in 

 this field to have in the same laboratory, workmg on the same strain of animals with the 

 same techniques of irradiation, parallel studies of histological conditions and the bio- 



