[11] As a further illustration of the differences which may exist in the purin metabolism in different kinds of animals, in man and the anthropoid apes the quantity of purin bases in the urine is small in proportion to the quantity of uric acid. In the pig, which is included among the animals that form allantoin from uric acid, the purin bases exceed the uric acid in amount, whereas in the dog, which likewise excretes allantoin, the purin bases exist in very small amount compared with the uric acid.—Stewart’s “Manual of Physiology.”
[12] The findings of Soetbeer and Ibrahim also indicate that 50 per cent. of the exogenous purin bodies undergo oxidation to uric acid, and 50 per cent. undergo further disruption and are excreted as urea or intermediate bodies.
[13] The subject of the experiments—a healthy male (M. S. D.), 22 years of age and 58 kilos in weight—was placed for over six months upon a meat-free low protein diet, free also from purin-containing beverages. This with the exception of a few meals in the holidays, during which a small amount of meat was taken. “No attempt was made to secure a quantitative uniformity of the diet.” On the evening preceding the day of an experiment a light supper was eaten, and no further food was ingested until the completion of the day’s experiment, save the substance whose influence on uric acid excretion was to be studied. The urine was collected hourly, 200 c.c. of water being ingested hourly throughout the experimental period.—“Uric Add Metabolism,” 11—H. B. Lewis, M. S. Dunn, and E. A. Doisy, “Journal of Biological Chemistry,” 1918.
Two other men also served as subjects. Many of the experiments were duplicated, and similar results obtained with these other subjects, but inasmuch as the experiments with M. S. D. were more comprehensive and extended over a longer period of time, the data of these experiments alone are presented.
[14] Quoting from the same article, Journal of Biological Chemistry, 1918, by Lewis, Dunn and Doisy, these authorities observe that—re glycocoll and alanine, Lusk concluded that “the chemical stimulation of protoplasm which is responsible for the phenomena of increased heat production (specific dynamic action) results from the action of their intermediary products, glycocollic and lactic acids, rather than from the amino-acids themselves. The phenomena of the stimulation of uric acid metabolism by amino-acids run parallel to those of the specific dynamic action of the amino-acids (except in the case of the dicarboxylic amino-acids), and it is possible that the same chemical factors are responsible for both.”
[16] Experimenting on a Dalmatian coach-hound, Gideon Wells was able to confirm Benedict’s observation that it excretes large quantities of uric acid. But inasmuch as the liver of this same dog was able to destroy uric acid in vitro, the inference is that the presence of uric acid in the urine of the Dalmatian is not attributable to the absence of uricase in its tissues. “The kidney did not exhibit uricolytic activity. Neither the liver nor spleen converted xanthine into uric acid, but the liver deaminised both guanine and adenine.”—Journal of Biological Chemistry, 1918.
[17] Wells, in his “Chemical Pathology,” observes that the amount of uric acid that appears in the urine depends upon a variety of factors which may be summarised as follows:—
(1) The amount of purin bodies taken in the food upon which chiefly depends the amount of exogenous uric acid.