[The late effects of radiation on hematopoietic stem cells and the possibility of their modification].

In experiments with mice it has been found that a radioprotective agent, mexamine (two different forms), administered prior to a whole-body single exposure at a dose of LD0/30 increases the average life of animals and the number of exoCFUs 8 days and has no influence on the number of exoCFUs 12 days. Mexamine does not modify the decrease of haemopoietic colonies in sizes in recipients, mice survived acute radiation sickness being used as donors. The share of CFUs 8 days at the stage of DNA synthesis has been shown to increase with age, as well as in animals which lived for 14 months after irradiation.