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Metabolism of lactose-[13C]ureide and lactose-[15N,15N]ureide in normal adults consuming a diet marginally adequate in protein

Metabolism of lactose-[13C]ureide and lactose-[15N,15N]ureide in normal adults consuming a diet marginally adequate in protein
Metabolism of lactose-[13C]ureide and lactose-[15N,15N]ureide in normal adults consuming a diet marginally adequate in protein
Oral lactose-ureide is resistant to human digestive enzymes, but is fermented by the colonic microflora. Nine normal adults consuming a diet which provided 36 g of protein/day were given oral doses of lactose-[(13)C]ureide and lactose-[(15)N,(15)N]ureide. The appearance on breath of (13)CO(2) derived from lactose-[(13)C]ureide was followed for 48 h. The fate of (15)N derived from lactose-[(15)N, (15)N]ureide was determined by measuring the recovery of (15)N in stools and urine in various forms. About 80% of the label given as lactose-[(13)C]ureide was recovered on the breath, and about 80% of label given as lactose-[(15)N,(15)N]ureide was not recovered in stool, indicating that 80% of the dose was completely fermented. At least 5% of the labelled urea was absorbed and excreted as the intact molecule. Of the (15)N derived from lactose-[(15)N, (15)N]ureide and available for further metabolic interaction, 67% was retained and 33% was excreted in urine. The time taken for [(15)N,(15)N]urea to appear in urine was similar for all subjects, but the appearance of either (13)CO(2) on the breath or [(15)N, (14)N]urea in urine varied. It is concluded that the hydrolysis of the sugar-urea bond may reflect oro-caecal transit time, but that other factors related to colonic bacterial metabolism determine the duration and extent of hydrolysis of urea by urease enzymes. Lactose-ureide can be used to probe the metabolic activity of the colonic microflora in normal individuals.
amino acids, colon, nitrogen, protein, stable isotopes, urea
0143-5221
547-55
Jackson, A.A.
c9a12d7c-b4d6-4c92-820e-890a688379ef
Bundy, R.
4ff21776-aa02-469e-9965-e2533cb3bde6
Hounslow, A.
7930ea2e-09cd-4757-afba-959d77015217
Murphy, J.L.
99e7863d-f870-438a-b4f5-bec8a2e78ebd
Wootton, S.A.
bf47ef35-0b33-4edb-a2b0-ceda5c475c0c
Jackson, A.A.
c9a12d7c-b4d6-4c92-820e-890a688379ef
Bundy, R.
4ff21776-aa02-469e-9965-e2533cb3bde6
Hounslow, A.
7930ea2e-09cd-4757-afba-959d77015217
Murphy, J.L.
99e7863d-f870-438a-b4f5-bec8a2e78ebd
Wootton, S.A.
bf47ef35-0b33-4edb-a2b0-ceda5c475c0c

Jackson, A.A., Bundy, R., Hounslow, A., Murphy, J.L. and Wootton, S.A. (1999) Metabolism of lactose-[13C]ureide and lactose-[15N,15N]ureide in normal adults consuming a diet marginally adequate in protein. Clinical Science, 97 (5), 547-55. (doi:10.1042/cs0970547). (PMID:10545305)

Record type: Article

Abstract

Oral lactose-ureide is resistant to human digestive enzymes, but is fermented by the colonic microflora. Nine normal adults consuming a diet which provided 36 g of protein/day were given oral doses of lactose-[(13)C]ureide and lactose-[(15)N,(15)N]ureide. The appearance on breath of (13)CO(2) derived from lactose-[(13)C]ureide was followed for 48 h. The fate of (15)N derived from lactose-[(15)N, (15)N]ureide was determined by measuring the recovery of (15)N in stools and urine in various forms. About 80% of the label given as lactose-[(13)C]ureide was recovered on the breath, and about 80% of label given as lactose-[(15)N,(15)N]ureide was not recovered in stool, indicating that 80% of the dose was completely fermented. At least 5% of the labelled urea was absorbed and excreted as the intact molecule. Of the (15)N derived from lactose-[(15)N, (15)N]ureide and available for further metabolic interaction, 67% was retained and 33% was excreted in urine. The time taken for [(15)N,(15)N]urea to appear in urine was similar for all subjects, but the appearance of either (13)CO(2) on the breath or [(15)N, (14)N]urea in urine varied. It is concluded that the hydrolysis of the sugar-urea bond may reflect oro-caecal transit time, but that other factors related to colonic bacterial metabolism determine the duration and extent of hydrolysis of urea by urease enzymes. Lactose-ureide can be used to probe the metabolic activity of the colonic microflora in normal individuals.

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Published date: November 1999
Keywords: amino acids, colon, nitrogen, protein, stable isotopes, urea
Organisations: Human Development & Health

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Local EPrints ID: 383840
URI: http://eprints.soton.ac.uk/id/eprint/383840
ISSN: 0143-5221
PURE UUID: 90c4f797-2685-4611-a5f1-d787b78d6869

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Date deposited: 25 Nov 2015 15:12
Last modified: 15 Jul 2019 20:58

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