ALKM'TOM h'lA 577 



tie effect when <i'iveii by inouth/'"' 'J'licii- detoxication is accomplished 

 by deainiiii/.ation and oxidatioii, the n'sultinjr (•ar])()xylic acids being 

 excreted or burned. Therefore it is not certain whether pressor bases 

 formed in the intestines have any pathological effect, but it is quite 

 possible that outside the portal territory various infections may give 

 rise to pressor bases which enter the general circulation directly and 

 escape the defensive mechanism of the liver. They may also cause 

 local effects in the tissues where they are formed, e. g., the bronchi. 

 In some respects their effects resemble those of anaphylactic intoxica- 

 tion, and as the latter apparently results from toxic products of protein 

 cleavage the possibility that here too pressor bases are concerned at 

 once presents itself, but as yet the relation is undetermined (see Ana- 

 phylaxis, Chap. vii). The resemblance is especially seen in the pro- 

 found effect on the bronchial musculature, which can be thrown into 

 strong contraction, especially by beta-iminazolyl-ethylamine which in 

 0.5 mg. doses kills guinea pigs from asphyxia, with distended lungs as 

 in fatal anaphylaxis; also it causes a similar fall in temperature, but 

 does not render the blood incoagulable. Another point of similarity 

 is the severe local urticaria when weak solutions (1-1000) of histamine 

 are placed on a scarified area of skin,*"*" recalling vividly the fact that 

 urticarial eruptions are conspicuous in some tj'pes of anaphjdactic 

 reactions.*^'^ 



ALKAPTONURIA ii 

 Alkaptonuria may be appropriately considered in this connection, 

 since it depends on an abnormal metabolism of the aromatic groups, 

 tyrosine and phenylalanine, which are, partly at least, split out of 

 the protein molecule in the intestine. This condition is character- 

 ized by the tendency of the urine to turn dark on exposure to air. 

 due to the presence in it of homogentisic acid.*- Homogentisic acid 

 has been found in the blood but not in the feces of alkaptonurics, and 

 the urine shows no other deviations from the normal except a slight 

 increase in ammonia, with which the acid is combined. It is of rare 

 occui-rence, persists throughout life with but little apparent effect 

 upon the health of the individual, and is often hereditary, being 

 grouped by Garrod along with cystinuria, pentosuria and albinism 

 as a "chemical malformation" of hereditarv^ origin.*^ The relation 



40b See Guggenheim and Loeffler, Biochm. Zeit., inifi {12), 32.). 



■toc Eppingcr and Outtmann. Zeit. klin. Med., 101.3 (78), 399. 



4id Sollniann lias found that several other amines give urticarial reaetions 

 (Jour, riiarni.. 1917 (9), 301). 



*i Resume and literature by Falta, Biochem. Centralhlatt. 1004 (3), 174. and 

 Deut. Arcli. klin. Med., 1904 (81), 231; Garrod, '-Inborn Errors of [Metabolism," 

 Oxford :Med. Publications. 1000; also Laneet, .Tulv, 1008; Frommherz, Bioehem. 

 Centr.. 1008 (8), 1. 



■42 It should be mentioned that hiidorhinon. when present in the urine (usually 

 after ingestion of large quantities of phenol), may also turn dark on exposure 

 to air; and melanin may be excreted as a chromogen which turns dark on ex- 

 posure, by patients with melanotic tumors or ochronosis {q. v.). 



•13 Alkaptonurics may give a positive WasserniauTi reaction without otlu-.- evi- 



