Indeed, they bring forward evidence that the process of urea formation, far from being localised to any particular organ, i.e., the liver, is almost ubiquitous.
Thus, experimenting with the injection of alanine, they noted that prior to the same the muscle content of non-protein nitrogen and urea nitrogen was respectively 194 and 26 mg.; but 180 minutes after the injection the non-protein content in muscle had risen to 232 and that of urea nitrogen to 41 mg. Working with glycocoll, the non-protein and urea nitrogen in muscle before injection of the same was 248 and 42 mg. respectively, while 240 minutes after injection the figures were 304 and 54 mg.
The significance of these figures is more striking when contrasted with the fact that in the same subjects the urea nitrogen content of the hepatic blood did not exceed that obtained almost simultaneously from the iliac artery. The deduction made by Folin and Denis is that—
(1) “The urea-forming process is one characteristic of all the tissues, and by far the greatest amount of the urea is, therefore, probably formed in the muscles.”
(2) “The negative results, so far as any localised urea formation is concerned, is almost satisfactory proof that there is none, for if there were one central focus from which all or nearly all of the urea originated we could scarcely fail to find it.”
Amino-Acids in Relation to Gout
The vista opened up by these advances in physiology suggested investigations into the amino-acids, their association with the output of uric acid in gouty patients. No less than eighteen different amino-acids enter into the constitution of protein, but of these the most interesting from our point of view is glycocoll or amino-acetic-acid. Now, glycocoll plays a great rôle in the organism as a detoxicating agent, rendering innocuous, e.g., benzoic and cholic acids by transmuting them into hippuric and glycocholic acids. In short, the body always has glycocoll at its disposal for coupling or combination purposes.
Now it appears likely that glycocoll can be split off from all the amino-acids, a probability reinforced by the results of the researches of Embden and Reese and Lipstein, these observers having shown that amino-acids are present in all urines to about 1 per cent. of the total nitrogen output.
Ignatowski, working with the urine of gouty patients, found amino-acids present in large amounts; not that it was peculiar to such subjects, for he found it in other diseases, but only traces were detectable in the urine of healthy individuals. Again, Walker Hall, investigating urines drawn from the subjects of gout, the victims of other diseases, as well as healthy and diseased children, determined the presence of glycocoll in about 70 per cent. of the cases. His researches, to his mind, confirmed the conclusion that “normally a certain amount of glycocoll escapes through or is eliminated by the renal filter.”
Burger and Schweriner, from their researches on gouty subjects, have confirmed Walker Hall’s findings as to the excretion in excess of amino-acids, especially glycocoll. Lastly, Almagia has in gouty urines detected the presence of glyoxylic acid. What its significance may be is uncertain, but it is at least interesting to note that, as MacLeod suggests, the synthetic formation within the body of glycocoll may very probably result from the interaction of ammonia and glyoxylic acid.