. . . lS +e find Vm . Mele . rr) peenC pict wasted: ; 3 k ee Fr ae ns ae ee Vegt 1 UNCLASSIMI@D. _ ot ~ : oo. . i . ‘ -o ADS RRLE ASPL Eo 7 ye BIOLOGY AND MEDICINE -The principal conclusions:of the conference were that: (1) mutation ralles recorded at © teeny: vanette ot Me “f Harwell and at Oak Ridge were in agreementas far as the studies went, an (2) studies at exposures between 37.5 and'300 roentgens are needed to bridge the gap betfreen the Harwell - and OakRidge studies. A similar conference at the Oak Ridge National Lal oratory is planned. for the summerof, 1958, following the Genetics Congregs in Montreal. STATUS OF TREATMENT OR IRRADIATION INJURY ~ em? SA The possibility has recently developed that a more effective treatmentfean be worked out for persons exposed to doses of radiation in the 200- to 600-roentgen range When it was found that irradiated mice could be saved by the ‘introduc on of material . from the spleen or bone marrow, it was first. believed that simple extracti¥es or perhaps pure — chemical substances could be found that would modify the lethal course of the radiation syndrome. This ideahas not been-completely abandoned, but emphasis has|shifted to trans- plantation of the progenitors of the cellular elements of the blood which wil . radiated animal and tide himover the period when the functioning of his ow depressed, . grow in the ir- - bone marrow is TS Severe depression amounting’to failure of blood formation in the bone harrow is re- - sponsible for most of the deaths which occur in animals some 7 to 30 days. ter exposure. Ordinarily, tissues transplanted from one individual to anather of the same[but not inbred strain, and even more definitely to another individual of a different strain gr species, are rejected and destroyed by the recipient.-In the animal which has been givenja lethal dose of radiation, however, this immune reaction is more or less lost, so that trangplants of bone marrow become a novel possibility with practical applications in man. 3 . Experimental work has shown that the irradiated animal will accept boge marrow.transplants from different strains and ‘species, but the transplant becomes incregsingly less success- ~ ful the greater the phylogenetic difference between the donor and the recipiqnt. Thus, it is found that the irradiated mouse will readily accept marrow from all other mice, but the transplant of rat marrow is less certain, and dog or human marrow apparently fails to take permanently. Conversely, the greater the genetic similarity between the donor ang Pelle ah At fete? | tower the dose of radiation needed for a ‘successful bone marrow trangplant§ the recipient, the Prior to this discovery concerning the effects of radiation on transplants, if was the gene ally accepted belief that transplants in man are possible only between identical tissues. i which were all definitely those of the rat; in some instances the.mouse’s ow ay 3 These marrow transplants are not merely stopgaps, for it has been shown ina number of ways that the transplanted cells-continue to live and function in the .recipien For example, some irradiated mice which have received rat bone marrow have recovered from the radia- x tion syndromeand then continueto live out theirlife span, but with circulat: recover sufficiently to suppress the rat cells completely; in others themouge will have cir- Sut AES Seep fore Sao ee culating blood cells of both species. Problems in methods of securing, handling, storing, and preserving mafrow are largely technical, and their satisfactory solution canbe anticipated with a fair degrde of confidence. On the other hand, it is evident from these new findings that knowledge of in munology and the general field of tissue transplantation is deficient. , Knowledge concerning the immune relationships between lower animaishis of definite value in establishing the patterns to be studied and explored in developing a practifal clinical application of marrow transplantation. Idiotransplants are presently feasible; sufh a transplant “ fe ve a owes ge DOEARCHIVES UNC ASSIFIED