Fluorescein as a Sensitive, Semiquantitative 

 Indicator of Injury Following Alpha Particle 

 Irradiation of the Brain* 



D. C. Van Dyke, P. Janssen, and C. A. Tobias 



Donner Laboratory, University of California, Berkeley, California, and 

 the Armed Forces Institute of Pathology, Washington, D.C. 



Soluble fluorescein U.S. P. i Uranine I . a dye routinely used by physicians 

 as a convenient and sensitise indicator of damati,e to corneal epithelium, has 

 been found to be an equally con\enient. semiciuantitative, and sensitise indi- 

 cator of irradiation injury to brain tissue. The use of this method as an indi- 

 cator ot dama(;e to brain tissue is based on the same piinciple as its use as an 

 indicator of corneal epithelial damage, i.e., normal brain tissue, like normal 

 corneal tissue, does not stain, whereas injured tissue of both types readily 

 takes up the dye. The method is Cjuantitative, since the intensity of staining 

 is dependent on the sexerity and number of injured cells. Permeability of 

 the tissue to fluorescein represents a physiologic or biochemical alteration 

 of the cell which precedes morphologic changes demonstrable by light 

 microscopy. 



The inxasion of brain tissue by cells which are normally permeable to 

 fluorescein can be recognized by the fact that they fluoresce following admin- 

 istration of the dye. This fact has been successfully used as a technicjue to 

 locate brain timior tissue at surgery (Moore, 1953). 



This paper describes the use of fluorescein staining as a sensitive and semi- 

 quantitati\e indicator of injury to brain tissue following localized irradiation 

 with a beam of alpha particles from the 184 in. cyclotron. The method has 

 been used to demonstrate the difference in radiosensiti\itv of brain tissue in 

 difTerent species. 



Material and Methods 



Male rats of the Long-E\ans strain, 28 clays of age at the time of irradia- 

 tion, were used, except when the eflect of age difference was in\estigated. 

 Young adult cynomolgus monkeys and rabbits of the New Zealand White 



* Supported in part by the U.S. .-Xtomic Energy Commission. 



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