[Show abstract][Hide abstract] ABSTRACT: Background
Most methods of assessing colonic motility are poorly acceptable to patients. Magnetic resonance imaging (MRI) can monitor gastrointestinal motility and fluid distributions. We predicted that a dose of oral polyethylene glycol (PEG) and electrolyte solution would increase ileo-colonic inflow and stimulate colonic motility. We aimed to investigate the colonic response to distension by oral PEG electrolyte in healthy volunteers (HVs) and to evaluate the effect of single 2 L vs split (2 × 1 L) dosing.Methods
Twelve HVs received a split dose (1 L the evening before and 1 L on the study day) and another 12 HVs a single dose (2 L on the main study day) of PEG electrolyte. They underwent MRI scans, completed symptom questionnaires, and provided stool samples. Outcomes included small bowel water content, ascending colon motility index, and regional colonic volumes.Key ResultsSmall bowel water content increased fourfold from baseline after ingesting both split (p = 0.0010) and single dose (p = 0.0005). The total colonic volume increase from baseline was smaller for the split dose at 35 ± 8% than for the single dose at 102 ± 27%, p = 0.0332. The ascending colon motility index after treatment was twofold higher for the single dose group (p = 0.0103).Conclusions & InferencesIngestion of 1 and 2 L PEG electrolyte solution caused a rapid increase in the small bowel and colonic volumes and a robust rise in colonic motility. The increase in both volumes and motility was dose dependent. Such a challenge, being well-tolerated, could be a useful way of assessing colonic motility in future studies.
Neurogastroenterology and Motility 07/2014; · 2.94 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: There is considerable interest in manipulating the behaviour of dietary emulsions in the human stomach as a means of altering satiating properties of fatty foods. However assessing this using intubation markedly disturbs normal gastric motility so a non-invasive imaging approach has a strong rationale. Two 20% sunflower oil-in-water fat emulsions test meals with different droplet sizes (termed Fine and Coarse) and intragastric behaviours were used to demonstrate, for the first time, the feasibility of carrying out magnetic resonance spectroscopy (MRS) measurements of fat emulsions fat fraction, in vivo, in the gastric lumen of 6 healthy volunteers. Magnetic resonance imaging (MRI) confirmed that as expected the Fine emulsion remained mostly homogeneously distributed inside the stomach over the course of 3 hours but the Coarse quickly creamed showing an upper layer much richer in fat. The MRS measurements showed that the Coarse emulsion had an upper layer of high lipid/water ratio compared to the lower layer. The fine emulsion fat fraction values remained stable throughout the study with no difference between upper and lower layers. It is therefore possible to quantify in vivo, in the gastric lumen, the intragastric fat fraction of oil-in-water fat emulsions using non invasive MRS techniques.Practical applications: This study shows that it is possible to quantify in vivo, in the gastric lumen, the intragastric fat fraction of oil-in-water fat emulsions using non invasive magnetic resonance spectroscopy techniques. These measurements can help improve understanding of intragastric distribution of fat, its relation to satiety, can improve the relevance of in vitro / in vivo models of fat digestion, and will ultimately aid the design of foods with desired health promoting characteristics and check their performance in vivo.
European Journal of Lipid Science and Technology 07/2014; · 2.03 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Colonic transit tests are used to manage patients with Functional Gastrointestinal Disorders. Some tests used expose patients to ionizing radiation. The aim of this study was to compare novel magnetic resonance imaging (MRI) tests for measuring orocecal transit time (OCTT) and whole gut transit time (WGT), which also provide data on colonic volumes.
21 healthy volunteers participated. Study 1: OCTT was determined from the arrival of the head of a meal into the cecum using MRI and the Lactose Ureide breath test (LUBT), performed concurrently. Study 2: WGT was assessed using novel MRI marker capsules and radio-opaque markers (ROMs), taken on the same morning. Studies were repeated 1 week later.
OCTT measured using MRI and LUBT was 225 min (IQR 180-270) and 225 min (IQR 165-278), respectively, correlation rs = 0.28 (ns). WGT measured using MRI marker capsules and ROMs was 28 h (IQR 4-50) and 31 h ± 3 (SEM), respectively, correlation rs = 0.85 (p < 0.0001). Repeatability assessed using the intraclass correlation coefficient (ICC) was 0.45 (p = 0.017) and 0.35 (p = 0.058) for MRI and LUBT OCTT tests. Better repeatability was observed for the WGT tests, ICC being 0.61 for the MRI marker capsules (p = 0.001) and 0.69 for the ROM method (p < 0.001) respectively.
The MRI WGT method is simple, convenient, does not use X-ray and compares well with the widely used ROM method. Both OCTT measurements showed modest reproducibility and the MRI method showed modest inter-observer agreement.
Neurogastroenterology and Motility 10/2013; · 2.94 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Loperamide (LOP) is an anti-diarrhoeal agent which is thought to act largely by slowing transit with an uncertain effect on the fluid content of the small and large bowel in humans. Adding simethicone (SIM) to LOP improves its efficacy, but the mechanism of interaction is unclear. Novel MRI techniques to assess small bowel water content (SBWC) have shown that mannitol solutions markedly increase SBWC and can be used as a model of diarrhoea.
We aimed to use quantitative MRI techniques to compare the actions in the gut of LOP and LOP + SIM in a model of secretory diarrhoea using mannitol.
A total of 18 healthy volunteers ingested capsules containing placebo (PLA) or 12 mg LOP or 12 mg LOP + 125 mg SIM. After 100 min they were given a drink containing 5% mannitol in 350 mL of water. They underwent baseline fasting and postprandial serial MRI scans at 45 min intervals for 4.5 h after ingesting the drink. A range of MRI sequences was acquired to image the gut.
LOP and LOP + SIM significantly accelerated gastric emptying (P < 0.03) and reduced SBWC during the late phase (135-270 min after mannitol ingestion), P < 0.009, while delaying arrival of fluid in the ascending colon (AC). The relaxation time T2 of the contents of the AC was reduced by both drugs (P < 0.0001).
LOP and LOP + SIM accelerate gastric emptying, but reduce small bowel water content which may contribute to the delay in oral-caecal transit and overall anti-diarrhoeal effect.
[Show abstract][Hide abstract] ABSTRACT: Preoperative fasting induces metabolic stress and leads to reduced postoperative insulin sensitivity, changes attenuated by preoperative carbohydrate loading. However, the mechanisms underlying these effects remain unknown. We investigated the dynamic changes in substrate metabolism and mononuclear cell mitochondrial function after fasting followed by refeeding with a drink [ONS (Fresenius Kabi, Germany)] designed to improve metabolic function preoperatively.
Twelve healthy volunteers took part in this study. They were fed a standardized meal and studied 4h later (baseline 'fed' state), after 12 and 24h of fasting, and 2, 4 and 6h after ingestion of ONS (contained 100g carbohydrate, 30g glutamine, and antioxidants). Changes in liver and muscle glycogen and lipids were studied using (13)C and (1)H magnetic resonance spectroscopy. The activities of mitochondrial electron transport chain complexes I, II and IV in blood mononuclear cells were measured spectrophotometrically.
Compared to the baseline fed state, 12 and 24h fasts led to 29% and 57% decreases (P<0.001) in liver glycogen content, respectively. Fasting for 24h decreased mitochondrial membrane complexes I (-72%, P<0.05), II (-49%, P<0.01) and IV (-41%, P<0.05) activities compared to those following a 12h fast. A 23% increase (P<0.05) in calf intramyocellular lipid (IMCL) content occurred after a 24h fast. Liver glycogen reserves increased by 47% (P<0.05) by 2h following ingestion of ONS.
Short-term fasting (up to 24h) affected mononuclear cell mitochondrial function adversely and increased IMCL content. Refeeding with ONS partially reversed the changes in liver glycogen.