CYSTINUKIA 535 



that present in normal urines. Diamins were looked for by the benzoyla- 

 tion method and by precipitation with phenylisocyanate. Increased 

 protein ingestion was followed by increased cystin excretion. After cystin 

 ingestion (by mouth) nearly all the sulphur was excreted as inorganic 

 sulphate. Two grams of tyrosin given during one day was apparently 

 destroyed. No diamins could be detected in. the cystinuric's urine. 

 Examination for leucin and tyrosin was also followed by negative results. 



Wolf, Shaffer, Osterberg and Somogyi found that the anomalies of 

 metabolism in cystinuria are low ammonia, high undetermined nitrogen 

 and high neutral sulphur. High undetermined nitrogen in part is due to 

 cystin, and in part to other amino acids. High neutral sulphur is prob- 

 ably due entirely to cystin. The cystin in the urine is largely, but not 

 wholly, of exogenous origin. The cystin sulphur oi the protein molecule 

 is not absorbed as such. Cystin and cystein administered by mouth are 

 catabolized to sulphate. When these are given subcutaneously they are 

 partially oxidized and partially excreted unchanged. Undiminished 

 tolerance for cystin given by mouth to the cystinuric was found confirm- 

 ing the results of Alsberg and Folin. Sulphur-free amino acids, admin- 

 istered by mouth, were quantitatively catabolized. Creatin and creatinin 

 given the cystinuric by mouth were eliminated just as by normal indi- 

 viduals. Administration of sodium cholate did not noticeably affect the 

 output of neutral sulphur. The administration of cystin by mouth ap- 

 peared to raise the sulphur excretion in the bile. After diversion of the 

 bile from the intestine by biliary fistula, the cystin disappeared from 

 the urine, but results with other cases indicate that there is no causal 

 connection here. High undetermined nitrogen continued after cessation 

 of the cystin excretion. 



The tables on page 534 are taken from the work of Wolf and his col- 

 laborators. 



One quality of cystin stones is to be mentioned, i. e., their easy recog- 

 nition by X-ray, as reported by Kienbock and Morris. Von Hoffmann 

 observed that while in the bladder they are easily crushed and are in- 

 crustated with crystals of calcium phosphate, a fact which Wollaston 

 suspected. Wollaston thus described the cystin calculus: 



"In appearance these calculi resemble more nearly the triple phos- 

 phate of magnesia than any other calculus; but they are more com- 

 pact than that compound is usually found to be: not consisting of dis- 

 tinct laminae, but appearing as one mass confusedly crystallized through- 

 out its substance. . . . These calculi have a yellowish semitrans- 

 parency; and they have also a peculiar glistening luster, like that of a 

 body having a high refractive density." 



There is no doubt that cystin stones are more common than is thought 

 on account of the fact that they do resemble the triple phosphate stones 

 and for that reason are not investigated more thoroughly. 



