Chemical and Enzymatic Changes in Nerve 

 Cells Irradiated with High Energy Deuteron 



Microbeams* 



Wolfgang Zeman, Howard J. CIurtis, Dante G. Scari'elli, 

 AND Ruth Kleinfeld 



Indiana University Medical School, Indianapolis. Indiana. 



Brookhaven National Laboratory. Upton. New York, and 



Ohio State University, Columbus. Ohio 



In previous studies on the mouse brain, it was found that high energy 

 deuteron microbeams with a diameter of approximately 25 and 75 ^ will 

 produce nerve cell necrosis without any definite pennanent damage to inter- 

 stitial elements (Zeman ct al, 1959j. The first stages of this process can be 

 observed in histologic preparations at approximately 4 days after a surface 

 dose of about 400,000 rad delivered by a beam 0.025 mm in diameter. After 

 24 days, a complete loss of nerve cells has occurred, located strictly within 

 the area of the beam path. In other words, the lesion forms a cylinder, the 

 dimensions of which are determined by the reducing apertures and by the 

 depth range of the particles (Fig. 1). Nerve fibers, myelin sheaths, and 

 vessels do not appear altered. 



These findings are in contrast to lesions resulting from wider beams. With 

 beams of 1 mm diameter, it is impossible to produce only a selective nerve 

 cell necrosis within the beam path. With a surface dose of up to 4.800 rad, 

 nothing happens to the irradiated cortical neurons. With higher doses, 

 there is focal tissue necrosis resulting in small cystic lesions, which occur 

 predominantly at the end of the depth range of the deuterons (Fig. 2). To 

 destroy all ner\e cells within the path of a 1 mm beam, about 14.000 rad is 

 required, but this dose destroys all the other tissue elements as well. 



Since there is apparently no dosage using beams of 1 mm in diameter 

 which would selecti\ely destroy ner\e cells within the path of the beam with- 

 out also destroying the interstitial elements, microbeam irradiations seem to 

 aflford a unique opportunity to study one of the two different dose-dependent 



* This study was supported by a U.S. Public Health Ser\ice Grant and was per- 

 formed in part at Brookhaven National Laboratory under the auspices of the U.S. 

 .'Atomic Energy Commission. 



429 



