NEUTRON EFFECTS OX ANIMALS 75 



cc, at 25°, was added 0.25 ce. of 0.9 per cent H2O2; the time required for 

 appearance of the starch-iodine color was noted. The amount of enzyme 

 which caused appearance of this color in one minute was regarded as one 

 unit of peroxidase. In order to make a correlation between marrow sam- 

 ples, which vary considerably in fat and water content, nitrogen deter- 

 minations were made (by the Microchemical Department), and the units 

 of peroxidase calculated pei- mg. nitrogen. 



Catalase was determined under the sam.e conditions of pH, temperature 

 and concentration as were used for the peroxidase determinations, in order 

 to determine the relative activity of the two enzymes. Warburg man- 

 ometers with simple, single side-arm flasks were used. In the side-arm 

 was placed 0.05 cc. of 0.9 per cent H2O2, and in the main part of the flask 

 0.4 cc. of 0.1 M acetate bufter of pH 4.7, 0.05 to 0.4 cc. of marrow, and 

 enough water to make a total of 2.5 cc. The amount of oxygen liberated 

 was read on the manometers at different time intervals. The activity was 

 calculated in terms of H2O2 decomposed per minute per mg. nitrogen. 



RESULTS 



The values obtained in the washed marrow from neutron irradiated and 

 untreated rabbits aiul dogs are reported in Table I. The data show that 

 when the radiation has affected the animal to such an extent as to bring it 

 near death or cause death, no peroxidase was found in the l)one marrow 

 investigated. In the case of rabbit Xo. 2, a very low peroxidase value 

 was found. This animal had been near death toward the end of the radia- 

 tion treatment but on cessation of the radiation treatment was recovering. 

 In animals whose health was apparently not aft'ected by the radiation 

 and in untreated animals the peroxidase values were much higher and of the 

 same magnitude. Xo correlation can be made at this time between the 

 amount of radiation and the diminution of peroxidase in the bone m.arrow 

 because of the few animals studied. 



Evidence was obtained that little, if any, peroxidase was lest from the 

 marrow tissue during removal of the hemogloliin by washing. A peroxidase 

 value and a hemoglobin analysis was obtained on the wash water and the 

 peroxidase value compared to that produced by j^ure hemoglobin. The 

 hemoglobin content of the wash water accounted for th(> pcM'oxidase value 

 within reasonable limits. 



When zero peroxidase wtis reported, in Tal)le I, the experimental values 

 were actually negati^■c. This was due to a retardation of the reagent blank 

 time because of a lowering of the peroxide concentration which was a result 

 ot destruction of peroxide by catalase. By measuring the amount of 

 oxygen liberated under identical conditions, howe\-er, the change in the 

 peroxide concentration could be calculated. \Mu>n a con-ection for this 



