On the presence of beta-imidazolethylamine in the intestinal wall : with a method of isolating a bacillus from the alimentary canal which converts histidine into this substance / by Edward Mellanby and F.W. Twort.

  • Mellanby, Edward, Sir, 1884-1955.
Date:
[1912?]
Catalogue details

Licence: In copyright

Credit: On the presence of beta-imidazolethylamine in the intestinal wall : with a method of isolating a bacillus from the alimentary canal which converts histidine into this substance / by Edward Mellanby and F.W. Twort. Source: Wellcome Collection.

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    Barger and Dale do not account for the appearance of /3-imidazol- ethylamine in the intestinal mucous membrane and point to the probability that it is a normal product of the mucosa. On the other hand the possibility that it is present as a result of bacterial decomposition has always been prominent, particularly because Ackermann(s) has been able to obtain large quantities of the base by allowing fluids containing histidine to undergo putrefaction. A short time ago we published work (6) describing methods for isolating creatin-destroying micro-organisms from the alimentary canal. We have extended the general principle of one of these methods to the present research. The general principle is as follows : in the first place the conditions are determined under which a mixture of intestinal bacilli will carry out the definite chemical change required. When the bacilli producing the change are at their maximum growth relative to the remaining micro-organisms, sub-cultures are made on fresh media so constituted as to eliminate as far as possible the unsuitable micro¬ organisms and at the same time raise the percentage of the active bacilli. The mixed culture is if necessary carried through a series of media, some of which are simplified, while others contain additional substances. The chemical compound to be split up is present in all the media, for not only does it give the active micro-organisms a better chance to grow and survive, but without its presence in the medium it is impossible to know whether or not any micro-organisms producing the change are present. When, after repeated sub-culturing, a mixture is obtained which contains only a few varieties of micro-organisms and the desired bacillus in sufficient numbers, plate cultivations are made and the bacteria capable of effecting the specific chemical action obtained in pure colonies. The details of the process that we used will now be described. In order to test the media for the presence of the histidine base we used the method of Kehrer(7) which consists of testing its action on the isolated uterus suspended in oxygenated Ringer’s solution. We used the uterus of a virgin guinea-pig as recommended by Dale and La id- la w(8). As pointed out by these workers the action of (3-1. on the isolated uterus is most delicate, for a solution containing 1 in 5,000,000, as a rule, has a marked pressor effect. It is possible also by using such a physiological method to obtain a good idea of the amount of base present in the solution, by comparing its action with one of known strength. If a minute quantity of faeces be inoculated into tubes of medium