308 N. I. GRASHCHENKOV 



Fadeeva et al. (1957), Kotlyarevsky et al. (1957), and other authors using 

 animals exposed to various doses and types of radiation. 



The nature of the nervous system's response to the efifect of radiation 

 depends also on its condition at the moment of irradiation. 



Grigorev (1956), by administering various drugs to a patient before x-ray 

 therapy, showed that when the stimulatory process was intensified after 

 caffeine, the EEG response became much more intensive. When Bromural 

 was administered, variation in the electrical activity was barely noticeable, 

 and the EEG response to radiation was even less pronounced after adminis- 

 tration of quinine. 



Pomerantseva (1957) did not observe any radiation responses in animals 

 exposed to radiation during sleep. Death caused by radiation after the 

 animal had been awakened occurred a good deal later than in the control 

 animals. 



Kazaryan and Saakyan (1960) describe how the severity of radiation 

 damage is considerably reduced in animals in hypothermia. 



Soviet research workers have also studied the condition of the hematoen- 

 cephalic barrier in animals exposed to radiation. 



Stern and co-workers have shown that as a result of exposure to ionizing 

 radiation the resistance of the hematoencephalic barrier changes in two 

 stages. After irradiation, the transition of various indicators from the blood 

 to the brain, which can be noted only 45 minutes after irradiation, becomes 

 more intensive (Stern, 1957, 1960; Gromakovskaya and Rappoport, 1957, 

 1960; Goncharenko, 1960). Zaiko (1960) found that the peak increase in 

 the permeability of the barrier occurred the 4th day after exposure with 

 radioactive phosphorus (P^-). In the second phase the resistance of the 

 barrier increases. 



Stern's co-workers noted that by administering neurotropic preparations 

 (atropine, Novocaine, morphia), it was possible to alter at will the perme- 

 ability of the barrier structures. This result at the same time confirms the 

 fact that nerve factors play a part in the mechanism by which the barrier 

 is disturbed. 



Arlashchenko (1955), using fluorescein as an indicator in investigating the 

 condition of the hematoophthalmic barrier, showed that there is a sharp 

 increase in permeability directly after exposure to radiation. 



It has been found that the degree of disturbance to the histohematic 

 barriers is directly dependent on the dose of radiation (Arlashchenko, 1955; 

 Goncharenko, 1960). 



There is every reason to assume that disturbance of the function of the 

 histohematic barriers (in particular the hematoencephalic barrier) is one of 

 the important basic factors in causing damage to nerve tissue exposed to 

 ionizing radiation by making it easier for a number of alien and toxic sub- 



