580 GASTRO-INTESTIXAL "AUTOIXTOXICATIOX" 



In some cases of alkaptonuria a pignuMitation of the cartilages also 

 occurs, ochronosis, but the association is not constant; ochronosis may 

 occur without alkaptonuria, and conversely. (See "Ochronosis.") 



(2) SUBSTANCES ARISING FROM THE FATTY ACID RADICALS 

 (AMINO-ACIDS) OF PROTEINS 



As stated in the introductory chajitei', the protein molecule con- 

 sists of a combination of a great number of organic acids, of various 

 sorts, all of which have as a common characteristic the presence of an 

 NHo group attached to the carbon atom nearest the acid radical, the 

 a position; thus, R — CHNHo — COOH. A few of the amino-acids con- 

 tain an aromatic group, and the relation of these to intestinal decom- 

 position has been considered above. The greater number have a 

 simple fatty acid radical (the simplest amino-acid being glycocoll,. 

 CHoNHo — COOH), and from them are derived by intestinal putre- 

 faction substances that are, for the most part, chemically simple and, 

 as far as known, pathologically unimportant. From leucine alone is 

 derived a substance of known considerable toxicity, the pressor base 



isoann/linitine. 



>CH — CH, — CH, — NH, 

 CH3 



which is less powerful than the cyclic pressor bases described prev- 

 iously. Bain '^^^ found it the most abundant pressor base of the urine. 



Fattj^ acids may readily be formed from them by splitting out of 

 the NH, group ; thus acetic acid may be formed from glycocoll, 

 propionic acid from alanine, etc. Apparently butyric and acetic acid 

 are the acids most commonly formed in this way. Gaseous deriva- 

 tives, such as hydrogen, ammonia, carbon dioxide, and marsh-gas, are 

 also produced. Acet&ne is perhaps formed from these fatty acids; 

 it is often present in the intestinal contents, but may come from other 

 sources. 



Certain conditions of cyanosis have been designated as enteroijenous 

 cfjanosis, because of tlie belief that the methem()gh)bin responsible for 

 the cyanosis is caused by nitrites derived from intestinal putrefaction, 

 and demonstrable in the blood. ^" Presumably tlie nitrites come from 

 llic Xll.j groui)s of the protein molecule, the ('(don bacillus being an 

 active fornuM- of nitrites. Tender tlie same term are included the cases 

 of sulph-hcinoglohinemia. This condition is ascribed by Wallis"'" to 

 bacteria which produce from the proteins a hydroxylamine derivative, 

 capable of reducing oxyhemoglobin, and whicli lie finds jiresent in the 

 blood of patients with sul])li-hemogl()binemia. 



Diamines. — Of much interest are the substances that arc formed 



•"■"gwart. .)()iir. Kxp. Plivsiol., 1014 (S). 2-2!t. 



4(1 Sec rjilison. Quart. Jour. :Mo(1., 100" (1). -i!) : Wost and Clarke. Laiieet, 

 Feb. 2, in(»7; Davis. Lancet. Oct. 2ti. VM'l. 

 •-■•o Quart. Jour. Med., Oct., ]!»!:{. 



