158 NEUTRON EFFECTS ON ANIMALS 



due to direct effects of the irradiation. Food consumption in rats after 

 neutron irradiation is materially decreased and a reduced food consumption 

 indirectly depresses the num])ers of white blood cells in the peripheral blood. 

 Irradiation also may affect the function of the adrenals and the pituitary 

 and through a hormonal imbalance indirectly affect the blood count. 



No measurable recovery of the animals was evident during the short 

 intervals between irradiation periods, so far as the effect on the white blood 

 cell system was concerned. It would be interesting to know how long the 

 intervals between the application of the fractional doses of irradiation could 

 be extended before a difference in the effects of a total and a divided dose 

 could be detected. 



The changes in sedimentation may be due to a direct action of the ir- 

 radiation on the blood or they may be due to an indirect action. 



It is possible that blood sechmentation is influenced by substances re- 

 leased from injured tissues after neutron irradiation. Disturbances in 

 metabolism following irradiation may result in an alteration in the com- 

 ponents of the plasma, thus influencing the rate of blood sedimentation. 



SUMMARY 



Leukopenia, lymphopenia and neutropenia were found in rats following 

 doses of 11.3 to 113 n. The maximum decrease and rate of decrease in 

 number of white blood cells were greater with increasing amounts of neu- 

 tron irradiation. The rate of decrease following any individual dose was 

 greatest during the first 24 hours. The greater the dose, the longer was 

 the period of time recjuired for complete recovery. The lymphocyte ap- 

 peared to be more radiosensitive than the neutrophil. 



There was no significant difference between the effect on the white blood 

 cell count, absolute lymphocyte count or absolute neutrophil count of rats 

 when the total dose of 56.4 n or 113 n was given in one day and that when 

 interrupted doses were given over several days. 



An increased blood sedimentation rate was found in rats that had re- 

 ceived 56.4 n. The maximum increase occurred eight days after irradia- 

 tion. Thereafter the sedimentation rate decreased slowly until it reached 

 pre-irradiation values. 



REFERENCES 



(1) Farris, E. J., Am. J. Anal., 63, 325 (1938). 



(2) Dougherty, T. F., and White, A., Am. J. Anal., 77, 81 (1945). 



(3) Ershoff, B. H., and Adams, A. D., Jr., Fruc. Sac. Expll. Biol. Med., 62, 154 



(1946). 



(4) Ely, J. O., and Ross, M. IL, Chapter 17. 



(5) Cohn, E. J., Chem. Rev., 28, 395 (1941). 



(6) Sanigar, E. B., Chapter 15. 



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