! RIO A < 11 » AM' THE PI kim. BODIES 649 



tion) i" tlie kidneys. These problems have recently been very isider- 



ably simplified by the elaboration of an accurate method for the estima- 

 tion lit' tin uric-acid content of blood. 



By observing changes in the amounl of uric acid in the blood rati 

 than in ilic urine, the i tory factor is partly controlled, and it can 

 be completely so it' urine and blood are both investigated. Thanks to 

 the work of Polin, it is now possible to determine with an extreme de 



'_ r r< E accuracy the uric a< id in as little as 1" c.c. of 1>1 1. The imp 



tance of this achievemenl will be appreciated when we state thai prior 

 to Folin's work mi method existed by which uric acid could be approx- 

 imately measured even when large quantities of-blood were available 



Much of the work thai has been done by the use of this new method 



so far applied to the amounl of uric acid in the 1>1 1 of man in 



various diseases. We shall refer to these results inn liately, but 



meanwhile it is importanl to call attention to some very suggestive 

 observations concerning th( condition of uric acid in tht blood. For 

 many years there have been investigators who have thought that uric 

 acid can not be simply dissolved in the blood plasma, Like sugar or some 

 inorganic salt. It is believed by many that at least a portion of the uric 

 acid circulates in combination with nucleic (thymic) acid sec pagi 

 which would accounl for the fad thai some purines are catabolized in 

 the body when they are given in a combined state, as thymic acid, but 

 are excreted unchanged when ingested in a free state* When given freely, 

 certain purines adenine, for example— may moreover cause inflamma- 

 tion and calculus formation in the kidneys of dogs, a resull not obtained 

 when thymic acid is fed. 



Other observers have concluded thai uric acid exists as two isomeric 

 varieties, lactam and lactim, the monosodium salts of which i un- 



equal stability. The less stable o-sall is much more soluble in blood 



serum than the stable (8-salt. It is the o-sal1 thai 1" mes inc - 1 in 



the blood in gout, the deposition of urates in the 1 which is the 



must characteristic Bymptom of this disease, being caused by conversion 

 lit' the o-salts into ff-salts. The structural formulas of the two ison 

 are as follov 



II. X C :0 N COB 



I I 



:C C Mi HO.C <• Ml 



\ 



/ 



C.OH 



I I.N «• Ml \ ' 



[lactam modification forini (lactim^ 



unstable a urat< stal 

 . relal ively solul lativclj 



