title: A gamma variate model that includes stretched exponential is a better fit for gastric emptying data from mice.
abstract: Noninvasive breath tests for gastric emptying are important techniques for understanding the changes in gastric motility that occur in disease or in response to drugs. Mice are often used as an animal model; however, the gamma variate model currently used for data analysis does not always fit the data appropriately. The aim of this study was to determine appropriate mathematical models to better fit mouse gastric emptying data including when two peaks are present in the gastric emptying curve. We fitted 175 gastric emptying data sets with two standard models (gamma variate and power exponential), with a gamma variate model that includes stretched exponential and with a proposed two-component model. The appropriateness of the fit was assessed by the Akaike Information Criterion. We found that extension of the gamma variate model to include a stretched exponential improves the fit, which allows for a better estimation of T1/2 and Tlag. When two distinct peaks in gastric emptying are present, a two-component model is required for the most appropriate fit. We conclude that use of a stretched exponential gamma variate model and when appropriate a two-component model will result in a better estimate of physiologically relevant parameters when analyzing mouse gastric emptying data.
authors.affiliation: Department of Biochemistry and Molecular Biology and Department of Physiology and Biomedical Engineering, Division of Biomathematics, Mayo Clinic College of Medicine, Rochester, Minnesota;
authors.forename: Željko
authors.initials: Ž
authors.lastname: Bajzer
authors.affiliation: Enteric NeuroScience Program, Division of Gastroenterology and Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, Minnesota;
authors.forename: Simon J
authors.initials: SJ
authors.lastname: Gibbons
authors.affiliation: Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine, Rochester, Minnesota; and.
authors.forename: Heidi D
authors.initials: HD
authors.lastname: Coleman
authors.affiliation: Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, Minnesota.
authors.forename: David R
authors.initials: DR
authors.lastname: Linden
authors.affiliation: Enteric NeuroScience Program, Division of Gastroenterology and Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, Minnesota; farrugia.gianrico@mayo.edu.
authors.forename: Gianrico
authors.initials: G
authors.lastname: Farrugia
mesh_terms: D000818:Animals; D001944:Breath Tests / Q000379:methods*; D003198:Computer Simulation; D005260:Female; D005746:Gastric Emptying / Q000502:physiology*; D051379:Mice; D023421:Models, Animal; D008962:Models, Theoretical; D017711:Nonlinear Dynamics; D013270:Stomach / Q000502:physiology
keywords: empirical mathematical models; gastrointestinal tract; motility; smooth muscle