A SKIN TEST IN RADIOBIOLOGICAL STUDIES 



inside the apparatus. A magazine holds in rotatable discs a series of the 

 well-known Lovibond coloured glass standards of the three primaries red, 

 yellow and blue, and by rotating the discs a suitable selection of glasses can 

 be brought into the line of view in the right-hand side of the field to equal 

 the colour of the object on the left. A normal chest colour would be about 

 1 • 7 red, • 8 yellow, • 5 blue, whereas in cases of marked erythema the values 

 would be around 3-2 red, 1 • 1 yellow and 0-6 blue. The most convenient 

 method of tabulating measurements or plotting colour changes is on a linear 

 graph, taking the two predominant primaries and regarding the third 

 primary as an expression of dullness. Therefore, most skin or erythema 

 colours can be plotted as red against yellow, or each primary can be plotted 

 separately against time or other factors. 



SCREENING OF 'PROTECTIVE' SUBSTANCES 



A method of testing the capacity of substances to protect the skin from 

 X-ray damage was devised. Specimens of substances not identified except 



Table I. — Effect on skin reaction of injecting substances intradermally after irradiation 



The experiments were undertaken to test the method and not the efficacy of the chemical agents used. The 

 identity of the substances ^ to G was learned after the series of experiments was concluded. 



for their molar weight, and labelled A to G, were obtained through the 

 kindness of Professor A. Haddow and Dr. P. Alexander of the Chester 

 Beatty Research Institute. This series included substances which have no 

 protective action as well as substances with moderate and marked activity. 

 The strength of solutions used was -0251^1, 0-005M and 0-0025M. 

 In the first series of experiments 1ml of 0-025M solution of these sub- 

 stances was injected intradermally mimediately after a dose of 1,000 r to 1,500 r 

 (60 kV 10 mA filtration inherent in the tube shield only, 25 cm F.S.D., 

 H.V.L. 1 mm Al) was given to a circular and a crescent area of skin 

 of rabbits and the subsequent reaction observed. Some of the protective 

 agents, when injected at -025^1, produce locally a more or less intense 

 inflammatory reaction, and the injection on occasion has to be made 

 outside the irradiated area, intradermal diffusion of the agent being relied 

 upon. This was the case, for [i-mercaptoaethylamin, but with 0-005M 

 and 0-0025M solutions the inflammatory reaction was almost nil and the 



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