title: Analysis of the urinary glucose-[¹⁵N, ¹⁵N]-ureide content in the study of the lactose-[¹⁵N, ¹⁵N]-ureide metabolism in healthy humans.
abstract: OBJECTIVE
  Lactose-[(15)N, (15)N]-ureide is used to study the fate of the colonic urea-nitrogen metabolism. During the passage through the gastrointestinal tract, lactose ureide is hydrolysed to glucose ureide, which is absorbed to a limited extent from the small intestine and is excreted urinarily. In the present study, a procedure has been developed to quantify the urinary excretion of glucose-[(15)N, (15)N]-ureide. In addition, urine and faecal samples obtained during a dietary intervention study with the prebiotic lactulose were retrospectively analysed.
  
  
  METHODS
  The glucose ureide and lactose ureide content was measured by GC-MS in 19 healthy volunteers. After consumption of a standard test meal containing 75 mg lactose-[(15)N, (15)N]-ureide, six healthy volunteers performed a fractionated 24 h urine collection to investigate the urinary excretion of glucose-[(15)N, (15)N]-ureide. In 13 volunteers, the effect of lactulose administration on the urinary excretion of glucose-[(15)N, (15)N]-ureide was analysed.
  
  
  RESULTS
  The urinary excretion of glucose-[(15)N, (15)N]-ureide reached its maximum level in the 3-6 h urine collection and decreased in the 6-9 h urine. The label was still detectable in the 9-24 h urine collection. The cumulative excretion of (15)N-labelled glucose ureide after 24 h amounted 12.91%. No significant differences in glucose-[(15)N, (15)N]-ureide excretion were found in either of the urine fractions after administration of lactulose, compared with baseline. In none of the urine samples lactose-[(15)N, (15)N]-ureide was detected.
  
  
  CONCLUSIONS
  In conclusion, the results obtained in the present study indicated that the percentage dose glucose-[(15)N, (15)N]-ureide recovered in urine is rather constant and not influenced by the presence of lactulose.
authors.affiliation: Department of Gastrointestinal Research and Leuven Food Science and Nutrition Research Centre, University Hospital Gasthuisberg, KU Leuven, Leuven, Belgium.
authors.forename: V
authors.initials: V
authors.lastname: De Preter
authors.forename: E
authors.initials: E
authors.lastname: Houben
authors.forename: K
authors.initials: K
authors.lastname: Windey
authors.forename: A
authors.initials: A
authors.lastname: Luypaerts
authors.forename: K
authors.initials: K
authors.lastname: Verbeke
mesh_terms: D000328:Adult; D004032:Diet; D005243:Feces; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D005947:Glucose / Q000031:analogs & derivatives*; D006801:Humans; D007785:Lactose / Q000652:urine*; D007792:Lactulose / Q000008:administration & dosage; D008297:Male; D056692:Prebiotics / Q000032:analysis; D012189:Retrospective Studies; D014508:Urea / Q000031:analogs & derivatives* / Q000652:urine; D016482:Urinalysis / Q000379:methods*; D055815:Young Adult
chemical_list: D056692:Prebiotics; D007792:Lactulose; C121442:lactose ureide; C036060:glucosylurea; D014508:Urea; D005947:Glucose; D007785:Lactose