250 PYRIDOXINE AND RELATED COMPOUNDS 



SO that the resulting total activity may be in a measurable state; the ma- 

 terial is fed directly to the assay animals. Errors which are inherent in these 

 chemical manipulations are thus avoided. Moreover, animal assay measures 

 available, not "total," vitamin Be. 



There are two general methods which ha\'e been employed for the bioas- 

 say of vitamin Be; one is based upon the cure or prevention of the acrodynia 

 that is produced on a vitamin Be-deficient diet, the other upon the increase 

 in weight when graded doses of vitamin Be are added to the deficient diet.'" 

 Often, a combination of these two procedures is used. The rat is the experi- 

 mental animal most widely used. 



1. Acrodynia Rat Test 



The first biological assays of vitamin Be were based entirely, or for the 

 most part, upon the cure of rat acrodjaiia produced by the vitamin Be-de- 

 ficient diet.^^'" However, the curative procedure was not generally adopted 

 because of its many inherent weaknesses: (1) factors other than vitamin 

 Be are involved in the production and cure of rat dermatitis;''^' ^^ (2) sever- 

 ity of dermatitis varies with season ;^° (3) interpretations of resulting cures 

 are dependent largely upon subjective influences ;^^ and (4) the acrodynia 

 cannot be produced consistently in the hands of some investigators. ^^ Un- 

 doubtedly, much of the earlier work was unsatisfactory because the diets 

 were not completely free from traces of vitamin Be; a complete synthetic 

 diet was not available, thus necessitating the inclusion of natural products, 

 such as "eluate" and "filtrate" factors, in the diet. Supplee et al.,*^ on the 

 other hand, have used the onset of acrodynia as the basis of an assay 

 method. The}^ devised a basal diet which permitted the development of 

 acrodynia in practically 100 % of their animals in six to eight weeks. 



3" C. I. Bliss and P. Gyorgy, in Vitamin Methods, Vol. II, p. 214. Academic Press, 

 New York, 1951. 



31 P. Gyorgy, Biochem. J. 29, 760 (1935). 



32 N. Halliday and H. M. Evans, J. Biol. Chem. 118, 255 (1937). 



33 G. Lunde and H. Kringstad, Biochem. J. 32, 708 (1938). 



3' H. E. C. Wilson and G. K. Roy, Indian J. Med. Research 25, 879 (1938). 



35 H. A. Schneider, J. K. Ascham, B. R. Platz, and H. Steenl)ocl<, J. Nutrition 18, 



99 (1939). 

 ^^ M. K. Dimick and C. B. Schreffler, J. Nutrition 17, 23 (1939). 



37 E. J. Reedman, W. L. Sampson, and K. Unna, Proc. Soc. E.rpil. Biol. Med. 43, 112 

 (1940). 



38 T. W. Birch, J. Biol. Chem. 124, 775 (1938). 



3'-' 11. Sherman, Vitamins and Hormones 8, 55 (1951). 



'« P. Gyorgy, J. Nutrition 16, 69 (1938). 



•1 H. Sclmeider, II. Steenbock, and B. R. Platz, J. liiul. Chem. 132, 539 (1910). 



« W. L. Dann, J. Biol. Chem. 128, XVIIl (1939). 



" G. C. Supplee, R. C. Bender, and (). J. Kahlenbcrg, ,/. Nutrition 20, 109 (1940). 



