3D shape reconstruction of the esophagus from gastroscopic video

In gastroscopy, video endoscopic imaging is applied for the assessment of the esophagus. Video sequences which provide a narrow two dimensional insight are thereby generated. Three dimensional shape reconstructions from such video sequences offer opportunities for intuitive and enhanced visualization of the esophagus, providing additional contextual and geometrical information. Due to lack of features and the variability of the scene, the shape reconstruction bears a challenge for computer vision. In this contribution, a three dimensional reconstruction from gastroscopic video is presented by first computing a panorama image of the esophagus wall using a novel shape from shading approach followed by a 3D alignment of thereby provided 2D contours of the esophagus wall. The resulting 3D point cloud is then registered contour-wise, leading to a regular triangulation which is then texturized using the panorama image and visualized

Intravenous nicotinamide riboside elevates mouse skeletal muscle NAD⁺ without impacting respiratory capacity or insulin sensitivity

In clinical trials, oral supplementation with nicotinamide riboside (NR) fails to increase muscle mitochondrial respiratory capacity and insulin sensitivity but also does not increase muscle NAD(+) levels. This study tests the feasibility of chronically elevating skeletal muscle NAD(+) in mice and investigates the putative effects on mitochondrial respiratory capacity, insulin sensitivity, and gene expression. Accordingly, to improve bioavailability to skeletal muscle, we developed an experimental model for administering NR repeatedly through a jugular vein catheter. Mice on a Western diet were treated with various combinations of NR, pterostilbene (PT), and voluntary wheel running, but the metabolic effects of NR and PT treatment were modest. We conclude that the chronic elevation of skeletal muscle NAD(+) by the intravenous injection of NR is possible but does not affect muscle respiratory capacity or insulin sensitivity in either sedentary or physically active mice. Our data have implications for NAD(+) precursor supplementation regimens

Comparative analysis of oral and intraperitoneal glucose tolerance tests in mice

Objective: The glucose tolerance test (GTT) is widely used in preclinical research to investigate glucose metabolism, but there is no standardised way to administer glucose. The aim of this study was to directly compare the effect of the route of glucose administration on glucose and insulin kinetics during a GTT in mice.Methods: A GTT was performed in lean male and female mice and obese male mice and glucose was administered via the oral or intraperitoneal (I.P.) route. Samples were collected frequently during the GTT to provide a full time-course of the insulin and glucose excursions. In another cohort of lean male mice, plasma concentrations of insulin, c-peptide, and incretin hormones were measured at early time points after glucose administration. A stable-isotope labelled GTT (SiGTT) was then performed to delineate the contribution of exogenous and endogenous glucose to glycemia during the GTT, comparing both methods of glucose administration. Finally, we present a method to easily measure insulin from small volumes of blood during a GTT by directly assaying whole-blood insulin using ELISA and show a good concordance between whole-blood and plasma insulin measurements.Results: We report that I.P. glucose administration results in an elevated blood glucose excursion and a largely absent elevation in blood insulin and plasma incretin hormones when compared to oral administration. Utilising stable-isotope labelled glucose, we demonstrate that the difference in glucose excursion between the two routes of administration is mainly due to the lack of suppression of glucose production in I.P. injected mice. Additionally, rates of exogenous glucose appearance into circulation were different between lean and obese mice after I.P., but not after oral glucose administration.Conclusion: Reflecting on these data, we suggest that careful consideration be given to the route of glucose administration when planning a GTT procedure in mice and that in most circumstances the oral route of glucose administration should be preferred over the I.P. route to avoid possible artifacts originating from a non-physiological route. (c) 2022 The Author(s). Published by Elsevier GmbH. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)