Study day visit protocol
appetite, upper gastrointestinal symptoms
UPPER GASTROINTESTINAL SYMPTOMS
Participants attended the MRI centre, at the Sir Peter Mansfield Imaging Centre, at 8 am having fasted overnight. Following weighing, an intravenous cannula was inserted in a retrograde direction into a dorsal foot vein for the collection of blood samples. A small intradermal injection of 1 % lidocaine was administered at the site of insertion. A 3-way tap and primary giving set were attached to the cannula and an intravenous infusion of 0·9 % saline delivered slowly to keep the vein open throughout the study visit. Participants were then intubated with a 120-cm-length 8-French gauge (FG) fine bore nasogastric tube (NGP18/120L, HMC PREMEDICAL S.p.A. Italy), inserted through an anesthetised nostril as described previouslyThe first MRI scan (20 min including set-up) was undertaken to determine baseline values for SBWC, SMA blood fluxThe feed was then delivered at room temperature, via the tube, using a bespoke, MRI compatible, pressure bag system allowing constant adjustment of the drip rate so that a total of 300 ml of feed was delivered over 1 h (+ or – 6 min).During the 1 h of feeding and subsequent 3 h, MRI scans were undertaken approximately every half-hour; blood sampling continued at 10 min (glucose) and 20 min (insulin and gut hormones) intervals and VAS (upper gastrointestinal symptoms and appetite scores) were completed at 30-min intervals, prior to blood sampling.Four hours from the start of feeding, participants left the scanner, the intravenous cannula and nasogastric tube were removed, and they were offered a cheese, tomato and pasta meal (served at 82°C) which they were instructed to eat, with no time restriction, until they felt comfortably full as described previouslyParticipants left the unit having been instructed to follow their standardised food menu for the remainder of that day and the subsequent 2 d and to record compliance on the form provided. A fecal collection kit was provided for sampling of the first available fecal sample on the day of the study, and on each of the next 2 d. The participants were required to record all other stools using the adapted King’s Stool ChartFollowing a 7–14-d washout period consuming their habitual diet, participants repeated the previously stated protocol with the opposite feed delivered during the study visit.A repeat trial was conducted in a participant whose blood samples could not be taken during the MRI scans due to the cannula failing, having moved from the vein into adjacent tissue. The same protocol was repeated, but without scans, in the Sir David Greenfield Human Physiology Unit, University of Nottingham, having obtained further consent and undertaken a repeat screening.