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756 URINE.
ing to their determinations, in man with a mixed diet, the nitrogen of the
oxyproteic acids represented 3-6.8 per cent of the total nitrogen, and with
a milk diet it sinks to about one-half of this (Gawinski). In dogs it
amounts to 2 per cent of the total nitrogen (Ginsberg). In disease it
may rise, and in typhoid cases it may rise to 14.69 per cent of the total
nitrogen (Gawinski). In phosphorus poisoning this nitrogen fraction
is also markedly increased according to several observations. The
oxyproteic acids are considered, as above remarked, as intermediary
products of the protein metabolism, and Gawinski holds that the
elimination of their nitrogen runs parallel with the elimination of neutral
sulphur, so that this latter may serve as an approximate measure of the
elimination of these acids.
Abderhalden and Pregl » have shown that human urine normally contains
compounds which stand, perhaps, in close relation to the polypeptides, and
which on hydrolysis with acids yield at least a part of the moities existing in the
protein molecule. In the case investigated they obtained abundant glycocoll,
also leucine, alanine, glutamic acid, phenylalanine, and probably also aspartic
acid. The relation between these polypeptide-like bodies and the above-men-
tioned proteic acids and uroferric acid has not been investigated.
Henriques and Sorensen 2
have given further proof for the occurrence of
nitrogen in peptide combinations in the urine. They have shown by formol
titration that in normal urine amino-acid nitrogen occurs. It must be remarked
that they consider as amino-acid nitrogen not only the nitrogen occurring as amino-
acids but also the urine nitrogen directly titratable with formol, therefore also the
titratable amino-nitrogen in the oxyproteic acids, polypeptides or more com-
plicated protein derivatives. They have further shown that after boiling with
acid that the quantity of titratable nitrogen increases, and this increase which
in man may be 8.9-28.3 per cent of the amino-acid nitrogen, they consider as pep-
tide-like nitrogen. We have abundant literature 3
on the ways and means of
carrying out the formol titration in urines, considering the presence of ammonia.
Amino-acids may, when they are introduced into the body in large amounts,
also pass in part into the urine. This has been shown for r-alanine by R. Hirsch
in the dog, and by Plaut and Reese in dog and man, and for r-leucine by
Abderhalden and Samuely 4
in rabbits and by others using different amino-acids.
Embden and Reese, Forssner, Abderhalden and Schittenhelm, Samuely,
Embden and Marx 6
were able, by means of the naphthalene sulpho-
chloride method to detect glycocoll in normal human urine, and this glycocoll
must occur in the urine in a combination which is readily split by alkali. Although
1
Zeitschr. f. physiol. Chem., 46.
2
Henriques, Zeitschr. f. physiol. Chem., 60; Henriques and Sorensen, ibid., 63
and 64.
3
See Henriques and S6rensen, 1. c; Malfatti, Zeitschr. f. physiol. Chem., 61 and
66; de Jager, ibid., 62 and 65; Fry and Gigon, Bioch. Zeitschr., 22.
4
R. Hirsch, Zeitschr. f. exp. Path. u. Therap., 1; Plaut and Reese, Hofmeister’s
Beitrage, 7; Abderhalden and Samuely, Zeitschr. f. physiol. Chem., 47.
5
Forssner, Zeitschr. f. physiol. Chem., 47; Abderhalden and Schittenhelm, ibid.,
47; Samuely, ibid., 47; Embden and Reese, Hofmeister’s Beitrage, 7, with Marx,
ihi’l.. 11, which also cites the rather conflicting deductions of Neuberg and Wolgemuth
and of Hirschstein.
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