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In vitro validation of the lactose 13 C‐ureide breath test for equine orocaecal transit time measurement
Author(s) -
SUTTON D. G. M.,
PRESTON T.,
LOVE S.
Publication year - 2011
Publication title -
equine veterinary journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.82
H-Index - 87
eISSN - 2042-3306
pISSN - 0425-1644
DOI - 10.1111/j.2042-3306.2011.00406.x
Subject(s) - ingestion , gastrointestinal transit , breath test , chemistry , lactose , lactulose , in vivo , digestion (alchemy) , transit time , food science , chromatography , gastroenterology , biochemistry , medicine , biology , microbiology and biotechnology , transport engineering , engineering , helicobacter pylori
Summary Reasons for performing study: Validation of a reliable, noninvasive clinical test for quantification of equine orocaecal transit time (OCTT) is required. This would facilitate an evidence‐based approach to investigation and treatment of equine small intestinal disorders. Objectives: 1) Comparison of the lactose 13 C‐ureide breath test (LUBT) with the hydrogen breath test (H 2 BT) for OCTT measurement. 2) Identification of the characteristics of gastrointestinal microbial glycosylureide hydrolase activity in vitro . 3) Production of an optimised protocol for the LUBT for in vivo measurement of equine OCTT. Hypothesis: Significant lactose 13 C‐ureide ( 13 C‐LU) hydrolase activity is restricted to the large bowel. The rate of expiratory 13 CO 2 production after ingestion of the isotope will provide an indirect quantifiable measure of orocaecal transit rate. Requisite bacterial activity may be enhanced by a primer dose of unlabelled substrate as shown in Man. Methods: Combined LUBT and H 2 BT were performed in 8 healthy individuals. Analysis of sequential end expiratory breath samples was used to calculate OCTT and results compared. Digestion of 13 C‐LU was investigated in vitro using fresh faecal material or intestinal aliquots collected post mortem . Isotopic fermentation rate was measured by rate of appearance of 13 CO 2 . Results: Peaks in expiratory 13 CO 2 occurred in all individuals after ingestion of the labelled test meal, whereas H 2 expiration was variable. Both faecal and intestinal microbial digestion of 13 C‐LU were maximised by prior exposure to 12 C‐LU. Induced bacterial glucoseureide hydrolase activity was significantly greater in the caecum than in the small intestine (n = 10, P<0.05). Conclusions: Significant 13 C‐LU digestion is restricted to the equine large intestine under normal conditions, and is enhanced by prior exposure to 12 C‐LU, making 13 C‐LU a suitable noninvasive marker of equine OCTT. The LUBT is more reliable than the H 2 BT for measurement of equine OCTT.