VIII. EFFECTS OF DEFICIENCY 41 



agents by Gordon et aW Both thioiiracil and PABA (0.2 % and 3.0 % of the 

 food, respectively) administercred for 19 to 45 days eaiis(; marked thyroid 

 hyperplasia, basophilia, and appearance of "thyroidectomy" cells in the 

 anterior hypophysis, and increased resistance of rats to lowered barometric 

 pressures (190 mm. Hg.). These effects, however, are more pronounced with 

 thiouracil than with PABA. Both drugs reduce the basal metabolic rate; 

 neither alters the resistance of the rats to the degree of lung hemorrhage 

 or extent of eye cataract encountered at the reduced pressures. Thiouracil 

 inhibits normal weight gains and, after 38 days, induces slight anemia and 

 granulocytopenia. PABA, on the other hand, does not retard body growth 

 and exerts no effect on the blood picture. 



The effect of PABA on uptake of radioactive iodine by surviving slices 

 of sheep thyroid has been studied by Franklin et al.^^ This compound as 

 well as p-aminophenylacetic acid has a pronounced inhibitory effect on the 

 rate of conversion of inorganic iodide to thyroxine and diiodotyrosine. 



2. Mice 



Martin and Ansbacher^^ have reported that PABA is essential for the 

 prevention of achromotrichia in the black mouse fed a purified diet adequate 

 with respect to pantothenic acid. In the black mouse the administration of 

 hydroquinone causes an achromotrichia that may be cured, according to 

 Martin and Ansbacher,!"" with PABA. 



On the other hand, Fenton et aZ.,^°^ employing a number of purified diets 

 and working with two strains of mice (C57 and A) could find no evidence 

 for the essential nature of PABA in the diet of this species. Growth was 

 just as good in the absence of PABA and inositol as in their presence. Inosi- 

 tol did not provoke a requirement for PABA. 



Keresztesy et al}°^ reported that the inhibition of tumor growth by inosi- 

 tol previously noted by Laszlo and Leuchtenberger'°^ may be reversed with 

 PABA. Their chemotherapeutic experiments involved the use of groups 

 of seven or eight female Rockland mice bearing transplanted tumors of 

 similar size (sarcoma 180, 7 to 10 days after transplantation) and main- 

 tained on a normal diet. Each mouse of a group was injected intravenously 

 twice a day for 2 consecutive days with the substance or mixture of sub- 

 stances under test. Forty-eight hours after the first injection the animals 



" A. S. Gordon, E. D. Goldsmith, and H. A. Charipper, Endocrinology 37, 223 (1945). 

 38 A. L. Franklin, I. L. Chaikoff, and S. R. Lerner, /. Biol. Chem. 153, 151 (1944). 

 " G. J. Martin and S. Ansbacher, Proc. Soc. Expil. Biol. Med. 48, 118 (1941). 



100 G. J. Martin and S. Ansbacher, J. Biol. Chem. 138, 441 (1941). 



101 P. F. Fenton, G. R. Cowgill, M. A. Stone, and D. H. Justice, J. Nutrition 42, 257 

 (1950). 



">* J. C. Keresztesj^ D. Laszlo, and C. Leuchtenberger, Cancer Research 6, 128 (1946). 

 103 D. Laszlo and C. Leuchtenberger, Science 97, 515 a04.3). 



