GENERAL DISCUSSION 355 



Glucose and serum proteins prove to have a strong protective action 

 on erythrocytes. Ghicose and serum proteins in increasing the stal)iUty 

 of the surface layer of erythrocytes, also possess a clearly dehned 

 radiation })rotection . 



It was of interest to investigate by this same method the joint action 

 of cysteamine (AET, ascorbic acid, and adrenaline) and of serum 

 proteins on the surface layer of an erythrocyte. Experiments showed 

 that the addition of serum proteins reduces or completely removes 

 (given a sufficiently great concentration) the harmful action of the 

 cysteamine, (or AET, or ascorbic acid, or adrenaline) on the surface 

 layer of the erythrocytes. 



The serum proteins protect the surface layer of the erythrocytes 

 both from the damaging action of the radiation and also from the 

 damaging action of these substances. 



MANOILOV : I would like to touch on the question of the primary changes 

 that take place in the cells of a living organism under the effect of 

 radiation. In the beginning it seemed that the most radiosensitive 

 substances in the cells of living organisms were nucleic acids and 

 nucleoproteins. 



In Alexander's interesting paper, and also in many other communi- 

 cations at this symposium, it has been shown that changes in the nucleo- 

 proteins cannot be responsible for the development of radiation 

 injury in the cells. In his paper Alexander put forward the supposition 

 of the special sensitivity of the phospholipids which enter into the 

 composition of cellular membranes. Unfortunately, the experimental 

 proofs on behalf of this supposition were not given in the paper. 



In the course of the last ten years we have developed the point of 

 view that the most radiosensitive substances in cells are the chromo- 

 proteins, or speaking more accurately— the variable valency metal- 

 containing enzyme systems. Amongst them we include the cyto- 

 chromes and other iron-containing enzymes. 



It is known that these substances participate in processes con- 

 nected with the liberation of energy. It has already been noted for a 

 long time that after irradiation of the living organism, a sharp reduction 

 in the production of energy occurs. The cells of a living organism which 

 are irradiated in lethal doses are not in a condition to carry out the 

 oxidation of organic substances. 



This, from our point of view, depends upon the fact that penetrating 

 radiation directly destroys the metal-containing enzymes, and destroys 

 the tissues' normal cycle of oxidation. An injury to the mealt-con- 

 taining enzymes is the result of a rupture of the haematinic portion 



