62 P-AMINOBENZOIC ACID 



seemed to be without therapeutic vahie. The mechanism by which PABA 

 elevated sahcylate blood level was shown to be a depression of conjugation 

 of glycine with salicylate."^ After PABA, only small amounts of sahcyluric 

 acid appeared in the urine. In addition, the urinary acidity was increased, 

 and this decreased the renal clearance of free salicylate. The above holds 

 true in man, but not in dog. 



In experimental allergic encephalomyelitis of guinea pigs, Good et aL"^ 

 found that large doses of PABA plus salicylates had prophylactic value, 

 but no therapeutic action. Large doses of salicylates were less effective, 

 and PABA alone was actionless. 



No therapeutic or prophylactic value could be demonstrated with PABA 

 against myxoma or vaccinia viruses in eggs."'^ 



Rosenblum and Fraser,"^ in contrast to Dry, noted that PABA definitely 

 relieved both fever and joint pains in a series of nine patients with acute 

 rheumatic fever. Dosage was comparable to that used in rickettsial diseases. 



Recently, Wiesel and associates'^ reported the use of PABA Avith cortisone 

 in treatment of fifteen patients with severe rheumatoid arthritis. A com- 

 pletely ineffective dailj^ dose of cortisone (25 mg.) plus 12 g. of sodium 

 p-aminobenzoate daily brought about suboptimal control of the disease. 

 PABA alone was ineffective. The authors believed the action of PABA was 

 related to its ability to suppress hepatic inactivation of estrogens. 



XII. Detoxication of Arsenicals 



LEMUEL D. WRIGHT and PETER A. TAVORMINA 



The concept of competitive inhibition stimulated a host of investiga- 

 tors to attempt a demonstration of this phenomenon in a variety of sys- 

 tems. In an experiment designed to explore the behavior of PABA as an 

 inhibitor of the trypanocidal activity of carbarsone, Sandground^ made the 



H2NCONH— </ \— AsOsH, 



observation that PABA confers an exceedingly high degree of protection 

 in rats infected with Trypanosoma equiperdiim against the toxic properties 

 of the arsenical, without decreasing its trypanocidal effect. The adminis- 



"5 R. M. Salassa, J. L. Bollman, and T. J. Dry, /. Lab. Clin. Med. 33, 1393 (1948). 

 "" R. A. Good, B. Campbell, and T. A. Good, Proc. Soc. Exptl. Biol. Med. 72, 341 



(1949). 

 1" C. t. Lee, Proc. Soc. Exptl. Biol. Med. 75, 649 (1950). 



i'» H. Rosenblum and L. E. P>aser, Proc. Soc. Exptl. Biol. Med. 65, ITS (1947). 

 1 J. n. Sandground, Science 97, 73 (1943). 



