In vitro validation of the lactose ¹³C-ureide breath test for equine orocaecal transit time measurement

Sutton, D.G.M. , Preston, T. and Love, S. (2011) In vitro validation of the lactose ¹³C-ureide breath test for equine orocaecal transit time measurement. Equine Veterinary Journal, 43(S39), pp. 42-48. (doi: 10.1111/j.2042-3306.2011.00406.x)

Abstract

<b>Reasons for performing study:</b> 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.<p></p> <b>Objectives:</b> 1) Comparison of the lactose ¹³C-ureide breath test (LUBT) with the hydrogen breath test (H₂BT) 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.<p></p> <b>Hypothesis:</b> Significant lactose ¹³C-ureide (¹³C-LU) hydrolase activity is restricted to the large bowel. The rate of expiratory ¹³CO₂ 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.<p></p> <b>Methods:</b> Combined LUBT and H₂BT were performed in 8 healthy individuals. Analysis of sequential end expiratory breath samples was used to calculate OCTT and results compared. Digestion of ¹³C-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 ¹³CO₂.<p></p> <b>Results:</b> Peaks in expiratory ¹³CO₂ occurred in all individuals after ingestion of the labelled test meal, whereas H₂ expiration was variable. Both faecal and intestinal microbial digestion of ¹³C-LU were maximised by prior exposure to ¹²C-LU. Induced bacterial glucoseureide hydrolase activity was significantly greater in the caecum than in the small intestine (n = 10_, P<0.05).<p></p> <b>Conclusions:</b> Significant ¹³C-LU digestion is restricted to the equine large intestine under normal conditions, and is enhanced by prior exposure to ¹²C-LU, making ¹³C-LU a suitable noninvasive marker of equine OCTT. The LUBT is more reliable than the H₂BT for measurement of equine OCTT.<p></p>

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Preston, Professor Tom and Love, Professor Sandy and Sutton, Professor David
• Authors: Sutton, D.G.M., Preston, T., and Love, S.
• Subjects: S Agriculture > SF Animal culture > SF600 Veterinary Medicine
• College/School: College of Science and Engineering > Scottish Universities Environmental Research Centre; College of Medical Veterinary and Life Sciences > School of Biodiversity, One Health & Veterinary Medicine
• Journal Name: Equine Veterinary Journal
• ISSN: 0425-1644
• ISSN (Online): 2042-3306
• Published Online: 25 July 2011