FLUORESCEIN AS INDICATOR OF BRAIN INJURY 



375 



2 4 6 S iC i2 14 



Days after irradiation 



Fig. 5. A comparison of the development of a fluorescent lesion in the brains of 

 rats, rabbits, and monkeys, all gi\en the same dose (10,000 rad) through the same 

 aperture on the same day. 



with the dose-response curve in Fio. 3. one sees that the response obtained 

 in the rats in this experiment corresponded to a dose of approximately 1 1 ,000 

 rad, whereas the response in rabbits corresponded to approximately 15,000 

 rad, and the response in monkeys corresponded to something greater than 

 26.000 rad. Fiaure 6A illustrates the intensity i4-k) of fluorescein staining 

 of the monkey brain 24 hours after a dose of 11,000 rad. The photograph 

 was taken while the brain was still frozen, using ultra\iolet ligiit. Rats gi\en 

 the same radiation dose showed no fluorescein staining at 24 hoius and showed 

 onlv 1+ fluorescence at 5 days. The monkeys killed at 24 and 48 hoias had 

 generalized paralysis and periodic clonic con\ulsions, illustrating that not 

 only their permeability to fluorescein but also the functional capacity of the 

 tissue was altered. Figure 7 compares the morphologic changes seen in the 

 monkey brain 24 hours after a dose of 11,000 rad with the morphology of 

 the rat brain 24 days after the same dose delivered under identical conditions. 

 Figme 7A is a low power photomicrograph of the irradiated portion of 

 the brain from a companion monkey to that shown in Fig. 6A. The animal 



Fig. 6A. An illustration of the intensity (4 +) of fluorescein staining of the mon- 

 key brain 24 hours after 10.000 rad. The photograph was taken while the head was 

 still frozen, using ultraviolet light. Rats given the same radiation dose and killed at 

 the same time showed no fluorescence. 



Fig. 6B."Land"' camera picture taken at the time of irradiation, superimposed on a 

 roentgenogram of a monkey's skull for orientation. 



