CYSTINURIA AND DIAMINURIA 119 



normal economy undergo complete destruction. While in- 

 gested mono-aminoacids appeared in part in the urine un- 

 changed, cadaverin was excreted when lysin was introduced 

 and putrescin when arginin was given. According to Neu- 

 berg we should recognize different grades of cystinuria, 

 which is a pronounced familial diathesis: (a) mild cases 

 who excrete cystin but who oxidize other aminoacids, 67 and 

 (b) moderately severe cases by whom no mono-aminoacids at 

 all are spontaneously excreted but in whom an alimentary 

 aminuria and diaminuria exists. Only in (c) the most 

 severe cases are the aminoacids spontaneously excreted, as 

 in an instance observed by Abderhalden and Schittenhelm. 

 Special interest attaches to the case of a cystinuric indi- 

 vidual, who was able to use up aminoacids but poorly, dipep- 

 tids to better advantage, but with still more efficience the 

 more complex protein derivatives. 68 It can be seen from 

 such a case that this anomaly need not be associated with 

 serious metabolic faults and may continue for years without 

 manifesting itself by evident symptoms. As previously 

 stated (Vol. I of this series, p. 307, Chemistry of the Tis- 

 sues), cystin is closely related with taurin, one of the two 

 synthetic products of cholic acid occurring in the bile : 



CYSTEIN TAURIN 



CHj.SH CH,.HSO, 



CH.NH, > CH 2 .NH,. 



COOH 



If cystin be administered to normal individuals a large 

 part of its sulphur appears in the urine in oxidized form, as 

 sulphuric acid. If, however, along with cystin sodium 

 cholate be given, in the first place taurocholic acid in the bile 

 is apparently increased, 69 and a correspondingly increased 



91 Cases of Chas. E. Simon, C. Alsberg and O. Folin, A. E. Garrod and W. H. 

 Hurtley, H. B. Williams and C. G. L. Wolf. 



68 A. Lowy, and C. Neuberg, Biochem. Zeitsehr., 2, 438, 1906. 



"G. v. Bergmann (F. Hofmeister's Lab., Strassburg), Hofmeister's Beitr., 

 4, 192, 1904. 



