HOWARD H. VOGEL, .JR., DONN L. JORDAN AND SAMUEL LESHER 



using the C57 black mouse, an inbred strain, from the Roscoe B. Jackson 

 Memorial Laboratory in Bar Harbor, Maine. The results of these tests, 

 using daily streptomycin and isologous bone-marrow cells, are summarized 

 in Table 1. 



Combination of the Amino Acid, Cysteine with Bone Marrow and Streptomycin 



Treatment 

 Previous work from this laboratory has indicated that pretreatment of 

 neutron-irradiated mice with the amino acid, cysteine, effectively reduced 

 the radiation dose by approximately seven to eight per cent^. It seemed 



100 



90 



80 



70 



™ 60 



i_ 

 o 

 E 



> 



E 



D 

 O 



50 



AO 



30 



20 



10 



"I r 



u 



H2O injected controls 



Cysteine injected 



controls ISOOmg/kg 

 body weight pre- _ 

 irradiation 0-5c.c. 

 intraperitoneally 



8 12 16 20 2A 

 Days after irradiation 



28 



Figure 5. The protective effect of cysteine, injected 

 intraperitoneally into neutron-irradiated mice. 



probable, therefore, that a combination of this agent with the bone marrow 

 and streptomycin therapy described above might produce even better pro- 

 tection. Consequently, experiments could be carried out in the 'supralethal' 

 neutron dose range. 



A preliminary experiment was completed to test the effectiveness of 

 cysteine given intraperitoneally instead of intravenously as in our former 

 work with this sulph-hydryl-containing amino acid^ Since the bone-marrow 

 cells are most effective when injected into a vein after irradiation, it was 

 hoped that the intraperitoneal route could be used for the cysteine injection 

 prior to neutron exposure. The results of this experiment, shown in Figure 5, 

 indicated that the cysteine was effective by this route. However, it was 

 necessary to give higher doses than when the intravenous route was utilized : 

 mice given 0-5 c.c. of a 10 per cent cysteine solution (pH 7-8, 1800 mg/kg 



227 



