The regenerative ability of hemopoietic tissue following lethal x-irradiation in dogs.

By VIcroR PERMAN, EUGENE P. CRONKITE, VIcroR P. Bonn AND D u K. SORENSEN T HE SUCCESSFUL treatment of the hemopoietic phase of the acute irradiation syndrome m dogs following doses of radiation that are in the range of LD,00130 dose has been reported by Sorensen et a!.’ and Bagadasarov et al.2 The present study is concerned with the ability of hemopoietic tissue to regenerate spontaneously following doses of radiation in excess of the LD10013 day dose. The gastrointestinal and cerebral phases that occur with higher doses of radiation than were used in this study, along with the hemopoietic phase, constitute phases of the acute radiation syndrome.3’4 The hemopoietic syndrome, which in mammals is produced by doses of radiation in the range of LD50130 is characterized by severe bone marrow depression with non-survivors succumbing in the second or third week in most species. Leukopenia and thrombopenia are associated with infection and hemorrhage as causes of death in the hemopoietic phase.5 The use of antibiotics in controlling infections and reducing the mortality rate in irradiated mice, rats and dogs has been studied extensively.6-8 Several studies on dogs9-’3 indicate that antibiotics singly or in combination appeared to be somewhat effective in reducing the mortality in the LD50 range. The use of antibiotics alone or in combination with stored whole blood was ineffective in reducing the mortality when the dose approached the LD,00 range. The studies of Allen et al. indicate that the use of small quantities of fresh whole blood, when given according to a predetermined schedule, was ineffective in reducing the mortality rate in dogs receiving graded doses of whole body radiation. Several investigators have shown that the principal defect in postirradiation hemorrhage may be thrombopenia.152#{176} These studies have shown that infusion of fresh intact platelets (not lyophibized or disintegrated platelets) would correct postirradiation hemorrhage. Sorensen et a!.’ reported on the use of several antibiotics in conjunction with fresh whole blood transfusions, supportive therapy and good nursing care as being effective in reducing the mortality rate of whole body x-irradiated dogs with doses near the LD,00130 dose. Bagdasarov et al.2 have shown