RADIATION-PROTECTION AND RECOVERY FROM RADIATION INJURY IN ENDOTOXIN- TREATED MICE: HEMATOPOIETIC RECOVERY AND SENSITIVITY TO A SECOND RADIATION EXPOSURE
NAVAL RADIOLOGICAL DEFENSE LAB SAN FRANCISCO CA
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The radioprotective effects of endotoxins and the relationship between hematopoietic recovery and the rate at which the mouse returns toward a normal radiosensitivity after a conditioning exposure were evaluated. Both Pseudomonas polysaccharide PP and Typhoid-Paratyphoid vaccine TAB increased survival of irradiated mice, and the protective effect differed in two strains of mice. The protective effects of PP and hypoxia were additive and the composite protection ratio was 1.87. TAB was used in an attempt to accelerate hematopoietic recovery in sublethally irradiated mice. Although the numbers of circulating and mobilizable granulocytes were greater in TAB-treated animals than in controls during the second post-irradiation week, the TAB-treated animals did not show a more rapid recovery from radiation injury as evaluated by the split-dose technique. The numbers of circulating granulocytes may be of value in predicting the outcome of a radiation episode in terms of survival or death, but the number of granulocytes does not necessarily predict sensitivity to a second radiation exposure.