290 PENTOSURIA 



Chronic Pentosuria. The idiopathie form of pentosuria 

 is a complete puzzle to us. 



This is a comparatively uncommon anomaly of metab- 

 olism. Some twenty cases were collected a few years ago 

 from the general literature. Some of the cases were neuro- 

 pathic individuals, cocaine and morphine habitues ; in some 

 a family disposition was recognized. The abnormality does 

 not give rise to any special clinical symptoms. Carl Neu- 

 berg, to whom we owe much valuable progress in the chem- 

 istry and physiology of the carbohydrates, found that the 

 sugar eliminated by the case of chronic pentosuria which he 

 studied was directly different from the tissue pentose, 

 A-xylose, and was really an inactive arabinose. "It is a 

 recognized fact," says Neuberg, 59 "that all sorts of living 

 beings produce optically active forms exclusively, and acti- 

 vate racemic types offered to them by consuming one of the 

 components. The example of inactive urinary pentose is 

 the first instance of the occurrence of a racemic body in the 

 animal economy. By the construction of urinary pentose 

 pentosuria is characterized as a phenomenon sui generis." 

 While the inactive arabinose if introduced into the body of 

 a healthy individual (as shown by Neuberg and Wohlge- 

 muth) undergoes cleavage into its two components, one of 

 which undergoes decomposition, the other, however, 

 8-arabinose, appearing in the urine, we see that this cleavage 

 power may come to be lost by the economy of the pentosuric. 

 O. af Klercker 60 comes to the conclusion from his own 

 studies that in pentosuria the two complementally isomeric 

 pentoses are excreted in very varying proportions. While 

 they are sometimes, as in Neuberg >s case, in equal amounts, 

 the A-component may in some instances be in excess. It is 

 not known from what source the arabinose comes. Its 

 excretion, according to Blumenthal and Bial, is independent 



w C. Neuberg, Handb. d. Pathol. d. S'toffwechs., 2d ed., 2, 221, 1907. 

 80 0. af Klercker (Instit. of Med. Chem., Lund), Deutsch. Arch. f. klin. 

 Med., 108, 277, 1912. 



