BACTERIAL METABOLISM WITHIN THE BODY 687 



Histamin is a very reactive compound. According to Vaughan, one- 

 half milligram injected into a guinea pig will cause death very soon. The 

 symptoms elicited suggest in a striking manner those characteristic of 

 anaphylactic shock. There is a strong contracture of smooth muscle fiber, 

 including that of the bronchial musculature. The latter narrows the 

 lumen of the bronchi to a very small opening, which in connection with 

 the somewhat tortuous course of the respiratory tract, leads to asphyxia- 

 tion. There is also noticed a rapid fall of body temperature. According 

 to the observations of Dale and Laidlaw, however, the coagulability of 

 the blood in such cases is practically unaltered, which is a point of dif- 

 ference between this syndrome and that of anaphylaxis induced in a 

 sensitized animal with the homologous protein. 



It would appear from available evidence that the formation of the 

 aromatic amins, phenyl ethylamin, paraoxyphenyl ethylamin, beta indol 

 ethylamin, and beta imidazole ethylamin, under ordinary intestinal con- 

 ditions, is chiefly the result of the activities of the colon-proteus-mucosus 

 capsulatus group of bacilli. It is probable that these amins do not form 

 in detectable quantities when the proportion of carbohydrate to protein of 

 the food is sufficient, with existing alimentary conditions of absorption, to 

 provide at least a minimal amount of sugar at the intestinal levels where 

 these organisms ordinarily are found. A sour milk diet is supposed to 

 restrict or prevent the formation of amins, and of other putrefactive prod- 

 ucts as well. It should be remembered that a sour milk diet is one re- 

 stricted in protein, which of course reduces the amount of protein from 

 which the parent amino acids are derived. 14 The carbohydrate content of a 

 typical sour milk diet is decidedly increased in proportion to the protein. 

 This furnishes a readily utilizable source of energy for the bacteria of the 

 alimentary canal, and thereby switches their metabolism 1 from the protein 

 constituents. Under these conditions, lactic and acetic acids are produced 

 largely, in place of the amins and other putrefactive products. 



5. The Physiological Action of the Aromatic Amins 



Generally speaking, the amins containing the benzene nucleus, phenyl 

 ethylamin, paraoxyphenyl ethylamin, and indol ethylamin cause an in- 

 crease of blood pressure upon injection, paraoxyphenylamin being the 

 most powerful of this group. There is some theoretical ground for asso- 

 ciating the symptoms induced in experimental animals with a direct 

 stimulating action of the sympathetic system. Barger and Dale, in study- 

 ing this relationship, have made use of the term "sympathomimetic," 

 which seems to be appropriate. 



"Gelatin contains much less of the aromatic amino acids than the true proteins. 

 It can not replace protein in the diet, but may be of some value for temporary dietary 

 reduction in these compounds. 



