The use of 13C-labelled glycosyl ureides for evaluation of orocaecal transit time.
OBJECTIVE
In the present study, cellobiose-[13C]ureide and glucose-[13C]ureide were synthesized and tested as alternative substrates for noninvasive evaluation of the orocaecal transit time (OCTT).


METHODS
Experimental study.


METHODS
In total, 1 g cellobiose-[13C]ureide was administered together with a continental breakfast either without or after predosing of 5 x 1 g unlabelled cellobiose ureide on the day prior to study commencement. After 2 weeks, the same subjects ingested glucose-[13C]ureide (dosage: 0.57 g) either without or after predosing of the respective unlabelled ureide under identical conditions. Expired air samples were taken over 10 h. 13CO2-enrichment was measured by isotope ratio mass spectrometry (PDZ Europa, Sandbach, UK). The OCTT was calculated from the interval between 13C-ureide administration and the detection of a significant and sustained 13C-rise of 2 delta over baseline in breath.


METHODS
University of Rostock, Children's Hospital, Research Laboratory.


METHODS
Eight healthy adults aged 22-55 y.


RESULTS
After application of cellobiose-[13C]ureide and glucose-[13C]ureide OCTTs of 401 and 415 min, respectively, were measured. The predosing resulted in higher and steeper 13C-enrichments and caused a significant shortening of OCTTs of 265 and 287 min, respectively (P=0.012 and 0.017).


CONCLUSIONS
The onset of 13CO2-enrichment reflected the degradation of glycosyl-[13C]ureides by glucose ureide hydrolase. The predosing with unlabelled ureides prior to pulse labelling with cellobiose-[13C]ureide and glucose-[13C]ureide (the latter is the key substance of the enzymatic sugar-ureide degradation) led to an induction of enzyme activity and resulted in a more precise and similar estimation of the OCTT when using both 13C-labelled ureides.
Wutzke
K D
KD
Children's Hospital, Research Laboratory, University of Rostock, Rostock, Germany. klaus-dieter.wutzke@med.uni-rostock.de
Glasenapp
B
B
D000328:Adult; D001944:Breath Tests; D002245:Carbon Dioxide / Q000032:analysis; D002247:Carbon Isotopes; D004187:Disaccharides; D005260:Female; D005772:Gastrointestinal Transit; D005947:Glucose / Q000031:analogs & derivatives; D006031:Glycosylation; D006801:Humans; D008297:Male; D013058:Mass Spectrometry; D008875:Middle Aged; D009005:Monosaccharides; D013997:Time Factors; D014508:Urea / Q000031:analogs & derivatives
D002247:Carbon Isotopes; D004187:Disaccharides; D009005:Monosaccharides; C487968:cellobiose-ureide; D002245:Carbon Dioxide; C036060:glucosylurea; D014508:Urea; D005947:Glucose