METABOLISM OF THE NUCLEIC ACIDS 427 



intestinal bacteriostasis was maintained by means of oral sulfonamides, 

 showed that the intestinal flora are not responsible for the observed partial 

 breakdown of uric acid. 



It has long been recognized that there is a pathological accumulation 

 of uric acid or urates in human gout, and this observation has stimulated 

 further research into the metabolism of uric acid in man. Thus the amount 

 of the uric acid pool in normal and gouty individuals has been determined 

 by several groups of workers,'*" •^^^•'^^•^^'' who have found that, in the normal 

 man, the size of the pool of miscible uric acid is about 1000 mg. of which 

 between 60 and 80% is renewed each day. In gouty subjects, on the other 

 hand, the size of this miscible pool is increased, generally to upwards of 

 2000 mg. while the turnover is of the order of 50 % per day. The effects of 

 treatment A\dth colchicine, ACTH, and cortisone on the size and turnover 

 of the uric acid pool have been discussed by Bishop et al}^^ Benedict et al.,^^^ 

 in an attempt to study the metabolic defect which leads to an increased 

 uric acid pool, have observed that after administration of glycine-N'* 

 there is initially a greater rise, and subsequently a more rapid fall, in the 

 isotope content of the uric acid from gouty, as distinct from normal, patients. 

 These authors interpret this to mean that the uric acid in patients with 

 gout is formed more rapidly and possibly more directly from glycine than 

 normal, and that the increase in size of the uric acid pool is due to an over- 

 production of uric acid rather than to a failure in the mechanism of uric 

 acid excretion. 



3. The Catabolism of the Pyrimidines 



Very much less is known concerning the catabolism of the pyrimidines 

 than of, the purines. The feeding experiments of Cerecedo and his co-work- 

 gj.gi86-i92 haye indicated that, except for cytosine which is not readily ab- 

 sorbed, the pyrimidines are rapidly oxidized and excreted as urea and oxalic 

 acid. Plentl and Schoenheimer,'^' using uracil and thymine labeled with 

 N'^, found that the administered pyrimidines are broken down and excreted 

 as urea and ammonia, the urinary allantoin having negligible isotope con- 



183 C. Bishop, W. Garner, and J. H. Talbott, J. Clin. Invest. 30, 879 (1951). 



1" J. D. Benedict, P. H. Forsham, and DeW. Stetten, Jr., /. Biol. Chem. 181, 183 



(1949). 

 1" J. D. Benedict, M. Roche, T. F. Yu, E. J. Bien, A. Gutman, and D. Stetten, 



Metabolism. 1, 3 (1952). 

 '8« L. R. Cerecedo, /. Biol. Chem. 75, 661 (1927). 

 '" L. R. Cerecedo, /. Biol. Chem. 88, 695 (1930). 



188 L. R. Cerecedo, /. Biol. Chem. 93, 283 (1931). 



189 L. R. Cerecedo and O. H. Emerson, J. Biol. Chem. 87, 453 (1930). 



I'o O. H. Emerson and L. R. Cerecedo, Proc. Soc. Exptl. Biol. Med. 27, 203 (1929). 

 "1 J. A. Stekol and L. R. Cerecedo, J. Biol. Chem. 93, 275 (1931). 

 192 J. A. Stekol and L. R. Cerecedo, J. Biol. Chem. 100, 653 (1933). 



