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



The results of this experiment {Figure 3) tend to support the hypothesis. 

 Although daily streptomycin therapy alone (Group III) protected the 

 irradiated mice for at least nine days, protection was not evident thereafter; 

 the 30-day mortality figure (75 per cent) was not greatly reduced from that 

 of the saline-injected irradiated mice of Group IV (87 per cent). A single 

 bone-marrow injection (Group I) reduced the 30-day mortality to only 25 

 per cent. Most of these deaths occurred during the first eight days after 

 exposure, during the period of intestinal damage. When both agents were 



' 90 



80 



70 



J 60 

 o 



E 



0)50 



_> 



|ao 



o 

 30 



20 



10 



/ 



r 



Group IV 



Saline injected (30) 

 . i •- 



^/ Group 111 



Streptomycin 



injected (32) 



/ 



/■ 



/ 



/ 



/ 



/ 



Group I 



Bone marrow 



injected (32) 



Group II 



Bone marrow 



plus streptomycin (32) 

 . «— . 



10 



15 



20 



25 



30 



Days after irradiation 



Figure 3. Comparative protective effects of postirradiation 

 treatment with (a) streptomycin, {b) homologous bone- 

 marrow cells, and (c) both agents combined. CF No. 1 

 female mice irradiated with single dose of 350 rad of 

 fission neutrons at the CP-5 research reactor. Duration 

 of exposure: 46 minutes. 



combined (Group II), a synergistic protective action was observed; only 

 three mice of the 32 irradiated (9 per cent) died within the 30-day period, 

 in contrast to approximately 90 per cent in Group IV, which received 

 neither therapeutic agent. 



The CF No. 1 mouse used in these experiments, and obtained commercially 

 from Carworth Farms, is not a pure inbred line. Several skin transplants 

 have been attempted between individual mice of this strain and invariably 

 the homotransplants showed destruction within a two- week period. However, 

 the CF No. 1 mice protected by the bone marrow and streptomycin technique 

 did not show a significant delayed death {Figure 4). This 'homologous 

 disease ' often reported after homologous and heterologous marrow transplants, 



225 



