J. M. GARVAN, E. P. GEORGE, F. A. ROCKE AND S. VINCE 



the whole-body LDiqo can be given to the marrow, using colloidal ^^®Au, 

 with a mortality significantly less than 100 per cent, and without the gastro- 

 intestinal ulceration produced by the whole-body dose. It is well known 

 that on the microscopic scale the distribution of the colloid is patchy, and 

 that the effective radiation dose may be somewhat lower than the mean 

 tissue dosages we have vised. Regarding the question of lethality of dose, it 

 is also interesting to note that for, say, 2 • 5 kg rabbits with the regime using 

 1000 r whole-body irradiation, integrated gram-roentgen doses of the 

 order of 2-5x10^ gram-roentgens are given. However, with the isotopic 

 regime* the gram-roentgen dose, due to ^ irradiation, is of the order of 

 only 30 per cent of this figure. 



The assays have demonstrated that spleen uptake was variable to such an 

 extent that one cannot predict whether a given rabbit will receive an 

 haematologically significant dose to the spleen or will be left with a virtually 

 protected spleen. Since protection of the rabbit spleen without bone-marrow 

 transfusion does appear to have an enhancing effect on survival, haemo- 

 poietic recovery^" and on antibody productions^, it seemed advisable at 

 length to control this factor, so that the last series was splenectomized. As 

 yet, insufficient data on this series are available for any definite conclusions 

 to be drawn. 



For rabbits with intact spleens, at specific dosage levels of 2 to 3 mC/kg, 

 there is a higher survival rate in the case of those treated, but above and 

 below this range there was failure to differentiate between treated and 

 control rabbits. The findings on survival are consistent with those of other 

 workers on the effects of bone-marrow transfusions following whole-body 

 in-adiation^^' ^^. 



It is interesting to note that increased survival rate (75 per cent) and an 

 enhancement of the average rate of recovery of the leukocyte count were 

 achieved in the cases of double transfusion when one was made before the 

 fifth day. If the earlier transfusion was responsible for this result, then we 

 are faced with the problem of whether the chances of success could be further 

 enhanced by using some isotope with shorter half-life, for a transfusion 

 given on the fourth day may receive fiom residual radio-activity at these 

 specific dosage levels with ^^^Au, a roentgen dose shown to produce severe 

 aplasia of bone marrow in some cases. However, it is clear that, since 

 survival or non-survival may not necessarily correspond to success or failure 

 in transplantation, it may be possible to lower the administered dosage level 

 itself without necessarily impairing the chances of success in transplantation. 



It is not as yet established that a ti'ansplantation has taken place. With a 

 view to establishing positive identification of any such transplant which 

 may have occurred, we have now initiated investigations along the lines of 

 those employed by Porter^ for identification by haematological sex 

 determination. 



We would like to thank Professor Larimer D odds for his stimulation and interest 

 in the problem, and Dr. R. J. Walsh for many discussions. Mr. W. A. Sollich made 

 many useful suggestions concerning chemical problems and Mr. R. A. Nyman gave 

 much willing assistance in the management of the animals. 



* Using a specific dose of 2-5 inC/kg. 



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