420 JOSEPH H. PRATT 



splitting the purin ring. Ferments of the digestive glands do not have 

 this action. It is probable that the source of the increased output of urea 

 that follows the administration of nucleic acid is due to the bacterial 

 purinolysis in the intestine. 



The two nucleosids, adenosin and guanosin, injected subcutaneously 

 or intravenously in normal man lead to an increased output of uric acid. 

 The increase of the purin nitrogen in the urine accounts in some cases 

 for nearly all the purin nitrogen introduced into the body in the form 

 of a nucleosid (Thannhauser, Gudzent). 



The amino-nucleosids, guanosin and adenosin, may undergo deaminiza- 

 tion forming the two oxy-nucleosids, xanthosin and inosin. The fer- 

 ments involved are guanosin-deaminase (Jones(&)), and adenosin-deam- 

 inase (Amberg and Jones(a)). 



Guanosin can form guanin by means of guanosin-hydrolase (Jones 

 and Belt) and adenosin be changed to adenin by adenosin-hydrolase (Am- 

 berg and Jones (6)). Similarly xanthosin is converted into xanthin by 

 hydrolysis (Jones), and inosin into hypoxanthin (Amberg and Jones(a), 

 Levene and Medigreceanu(6)). 



Xanthin and hypoxanthin are oxidized to uric acid by the ferment 

 xanthin oxidase (Spitzer, Wiener). This is found in man in the liver only. 



The two aminopurins, guanin and adenin, are converted into xanthin 

 and hypoxanthin by the two separate ferments guanase and adenase, the 

 existence of which has been proved by Jones and his associates, Partridge 

 and Winternitz. Schittenhelm for years contended there was a, single 

 deaminase that changed the aminopurins into oxypurins. Jones (a), how- 

 ever, showed that the organs of different animals differ in the deaminases 

 they contain. For example, the ox-spleen contains both guanase and ade- 

 nase as Schittenhelm found, but pig's spleen contains adenase, but not 

 guanase. Adenase does not occur in any human organ. Guanase is pres- 

 ent in the kidney, liver and lung. While free adenin cannot be acted 

 upon by human tissues, combined adenin, i. e., adenosin can be deaminized 

 into inosin. 



Uric acid is apparently the end product of purin metabolism in man 

 and the ape (Wiechowski(o-) (c) ), but in lower animals it is oxidized to al- 

 lantoin by the ferment uricase (Stockvis(a), Wiener, Wiechowski(6)), 

 which has never been found in the human organism. Early experiments 

 seemed to show that uric acid injected subcutaneously was excreted quanti- 

 tatively. These results formed the chief support of those who claimed that 

 uric acid was not destroyed in man. Recent studies have reopened this 

 question which seemed definitely answered, and it is now known that a 

 considerable part of uric acid injected intravenously is often not excreted' 

 in the urine (Bass(fr), McClure and Pratt, Griesbach, Burger). In one 

 of my non-gouty cases only 22 per cent was eliminated. In Burger's series 

 the average output was only 52 per cent and the remainder retained in the 



