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AbstractBackgroundThe relationship between cardiovascular and gastrointestinal (ie, plasma pancreatic polypeptide [PP] response to modified sham feeding [MSF]) indices of vagal function is unclear. Hyperglycemia inhibits PP secretion via vagally mediated mechanisms. Our aims were to (a) compare the PP response, (b) its relationship with glycemia, and (c) the relationship between PP response to MSF, gastric emptying (GE) of solids, and symptoms during GE study in healthy controls, patients with diabetic gastroenteropathy (DM), and non‐ulcer dyspepsia (NUD).MethodsIn 24 healthy controls, 40 DM, and 40 NUD patients, we measured plasma PP concentrations during MSF, cardiovagal functions, GE, and symptoms during a GE study.Key ResultsBaseline PP concentrations were higher in DM than in controls and NUD (P = .01), and in type 2 than in type 1 DM patients (P < .01). The PP increment during MSF was normal (≥20 pg/mL) in 70% of controls, 54% of DM, and 47% of NUD patients. Overall, the PP response and cardiovagal tests were concordant (P = .01). Among patients with a reduced PP increment with MSF, 7/10 of T1DM and 1/7 of T2DM patients had moderate or severe cardiovagal dysfunctions (P < .05). The PP response to MSF was not associated with GE.Conclusions & InferencesUp to 30% of healthy controls have a reduced PP increment during MSF, limiting the utility of this test to detect vagal injury. The PP response is more useful when it is normal than abnormal. A reduced PP response is more likely to be associated with cardiovagal dysfunctions in T1DM than in T2DM.

INTRODUCTION: Reduced gastric accommodation (GA) or accelerated or delayed gastric emptying (GE) contributes to pathophysiology in functional dyspepsia (FD). Secretin is an endogenous hormone secreted postprandially from the duodenal mucosa. Our objective was to determine the effects of secretin in human gastric motor functions and satiation in health and FD. METHODS: We conducted a double-blind, randomized, placebo-controlled, cross-over trial in 10 healthy participants and 10 patients with FD by Rome IV criteria. Subjects were randomized to IV secretin or normal saline with a 1-4 week washout period. We measured GA using validated 99m Tc-single photon emission computed tomography with a standardized 300 mL meal of 111 In radiolabeled Ensure®. We measured GE using scintigraphy of the same meal and symptoms 30 minutes post meal based on 100 mm visualized analog scale (VAS). To measure volume to fullness (VTF) and maximum tolerated volume (MTV), we performed Ensure® nutrient drink test (NDT) and recorded symptoms 30 min post-MTV. Wilcoxon Signed-Rank Test was used for comparison within healthy and FD groups and ANCOVA modeling was used for intention to treat comparison between groups, adjusting for age, sex, and treatment arm (secretin vs. placebo). Study drug was provided by ChiroClin, Inc. RESULTS: The median age for healthy volunteers (HV) was 45.0 years [IQR: 38.0, 49.0 (80% female)] and for FD was 50.5 years [42.0, 55.0 (70% female)]. There was no statistical difference in either group for secretin vs. placebo for GA. Secretin delayed GE in both HV and FD (Table 1). There was decrease in GE for secretin vs. placebo in HV at 20 minutes [-10% (-13, -7), P = 0.008] and 30 minutes [-11% (-16, -4), P = 0.004]. This finding was also seen in the FD group for GE at 25 minutes [-5% (-9, 0), P = 0.047] and 30 minutes [-8% (-9, 0), P = 0.03]. There were no statistically significant differences between treatment arms for VTF or MTV in either HV or FD. On ANCOVA analysis, there were statistically significant increases in nausea at 30 minutes ( P = 0.0016) and fullness at 30 minutes ( P = 0.0002) for secretin vs. placebo in FD compared to HV. CONCLUSION: Secretin delayed GE in both healthy volunteers and FD without significantly altering GA, VTF, or MTV. Secretin receptor stimulation deserves further study in FD patients with accelerated GE.

INTRODUCTION: Increasing rates of obesity have led to increased numbers of bariatric surgeries performed world-wide. However, some patients do not achieve significant weight loss or develop weight regain following these procedures. Other than estimating the size of the gastric remnant at endoscopy or transaxial imaging, there are limited approaches to quantitate the function of the post-surgical stomach in order to evaluate the disparate weight patterns, or to develop strategy for future treatments, e.g., pharmacotherapy or endoscopic intervention. We hypothesize that altered gastric function in the pre- and post-surgical periods may offer an explanation. Studies performed thus far are difficult to interpret due to heterogeneity in approaches to diagnostic evaluation. The aims of this project were: to assess the feasibility of a new protocol for simultaneous evaluation of gastric accommodation and gastric emptying in the post-bariatric state; and to report normative values in healthy volunteers. METHODS: Methods: We utilized single photon emission computed tomography (SPECT) and gamma scintigraphy to concurrently study postprandial gastric accommodation responses and gastric emptying rates of a limited size meal designed for subsequent use in post-bariatric patients. The standard meal consisted of 1 egg and 1 extra egg yolk scrambled with 111 Indium-activated charcoal (∼130kcal, 9.5g fat) and 120mL 2% milk (130kcal, 4.4g fat). Gastric accommodation was measured using 99m Technetium-SPECT. SPECT imaging was obtained concomitant with gastric emptying of the 111 In-labeled meal. Anterior and posterior scans of the abdomen were obtained for estimating gastric emptying parameters every 15 minute until 90 minutes, and then in 30-minute intervals until 240 minutes or complete emptying. RESULTS: Data on 28/30 healthy volunteers (35.7% men; 67% Caucasian) with completed studies to date are shown in the Table 1 (data presented as mean ± standard deviation). Gastric emptying proportion at 1, 2, and 4 hours, T 1/2 , and gastric volumes including accommodation are graphically depicted in Figures 1 and 2, respectively. CONCLUSION: Discussion: This study has demonstrated feasibility of simultaneous measurement of gastric emptying and accommodation and provides normal values; this sets the stage for future baseline and post-operative scans on patients undergoing sleeve gastrectomy.

AbstractBackgroundNon‐ulcer dyspepsia (NUD) is a heterogeneous disorder, which is characterized by upper gastrointestinal symptoms and sensorimotor disturbances, including abnormal gastric emptying (GE) and increased intestinal chemosensitivity, and associated with greater plasma glucagon‐like peptide‐1 (GLP‐1) levels during duodenal lipid infusion. However, the relationship(s) between these disturbances and daily symptoms in NUD is variable. We hypothesize that abnormal GE and symptoms during a GE study and during duodenal lipid infusion are associated with the severity of daily symptoms and that GLP‐1 mediates symptoms during duodenal lipid infusion in NUD.MethodsGastric emptying of solids, symptoms during the GE study and duodenal lipid infusion, and daily gastrointestinal symptoms (2 week diary) were measured in 24 healthy controls and 40 NUD patients. During duodenal lipid infusion, participants received the GLP‐1 antagonist exendin 9‐39 or placebo.Key ResultsIn controls and patients, GE of solids was normal in 75% and 75%, delayed in 8% and 12.5%, or rapid in 17% and 12.5%, respectively. No controls but 26 patients (65%) had severe symptoms during the GE study. During lipid infusion, gastrointestinal symptoms were greater (P = .001) in patients and not affected by exendin. Symptoms during GE study and lipid infusion accounted for respectively 62% and 37% of variance in daily symptom severity.ConclusionsIn NUD, symptoms during a GE study and to a lesser extent during lipid infusion explain the variance in daily symptoms. Intestinal chemosensitivity is not reduced by GLP‐1 antagonist. Assessment of symptoms during a GE study may provide a useful biomarker for NUD in research and clinical practice.

INTRODUCTION: Aquaporin (AQP) channels are involved in regulating fluid homeostasis in the colon. Several AQP channels were detected in human colon epithelial cells. In a previous study, rats fed 1% (wt/wt) sodium cholate had increased AQP3, 7, and 8 levels, suggesting AQP involvement in bile acid diarrhea (BAD). Our aim was to compare AQP expressions in rectosigmoid mucosal (RSM) biopsies from patients with irritable bowel syndrome–diarrhea (IBS-D) (divided into those with normal or high fecal BA excretion) and in patients with IBS-constipation (IBS-C) compared with healthy controls. METHODS: In RSM biopsies from 44 patients with IBS-D (with normal (<) or high (>2,337 μmol/48 hours (BAD)) fecal BA excretion), 10 patients with IBS-C, and 17 healthy controls, we measured expressions of AQP1, 3, 7, and 8, with RT-PCR (housekeeper gene GAPDH ). We analyzed RNA for expression by RT 2 -PCR assays, with expression calculated using 2 −ΔΔCT -based fold-change. Comparisons of IBS groups were corrected for false detection rate (Bonferroni correction for 12 comparisons; P < 0.0042). AQP protein measurements on biopsies from 3 healthy controls, 3 patients with IBS-D, and 3 patients with BAD were performed by western blots (GAPDH housekeeping protein). RESULTS: In RSM from patients with IBS-D (but not IBS-C), mRNA expression of AQP3 was decreased, and AQP7 and 8 were increased relative to controls. Fold differences were not different in IBS-D with or without BAD. Western blots confirmed increased expression of AQP7 and 8 and decreased AQP3 proteins in biopsies from patients with IBS-D compared with controls. CONCLUSIONS: Increased AQP7 and 8 and decreased AQP3 expressions in RSM suggest that further studies on AQPs' potential role in the pathophysiology of diarrhea in IBS-D are warranted.

AbstractObjectiveTo compare estimates of gastric accommodation (GA) with single photon emission computed tomography (SPECT) to measurements based on intragastric meal distribution immediately post‐meal ingestion (IMD0).MethodsWe evaluated 108 diabetics with upper gastrointestinal (UGI) symptoms who had undergone gastric emptying of solids (GE) by scintigraphy and GA measurements by SPECT. Immediately after ingestion of a 99mTc‐labeled egg meal (time 0), we estimated IMD0 as radioactive counts or area of the proximal half of the stomach on two‐dimensional images. Gastric volume (GV) during fasting and after 300 mL Ensure® was measured by SPECT to quantify accommodation volume (AV) or postprandial to fasting volume ratio (GVR). From the measured proximal gastric area, we estimated the volume of proximal stomach (4/3 × π × r3). We performed regression analyses to assess relationships between IMD0 and GA (AV) and GVR.ResultsThere was a significant correlation between area and radioactivity counts in the proximal stomach (r = 0.67, P < 0.001); however, there was considerable interpersonal variation [bias 0.20 (95% CI −0.07, 0.47)]. There were no significant correlations between total GV or AV or VR by SPECT and measurements using IMD0: proximal gastric counts, area, and estimated volume as continuous variables of dichotomized patient groups, based on published cutoff values. There were no significant differences in total gastric area or the IMD0 parameters (% area or % radioactive counts) between those with and without UGI symptoms except for fullness and satiety.ConclusionsIntragastric meal distribution immediately post‐meal ingestion is not significantly correlated with GA measurement by SPECT.

SummaryBackgroundBiomarkers in irritable bowel syndrome (IBS) may guide targeted therapy in this multifactorial disease. It has been suggested that 75% accuracy and cost <$500 categorise biomarkers as cost‐effective.AimTo identify differences in faecal bile acids, faecal fat and fasting serum C4 (7a‐hydroxy‐4‐cholesten‐3‐one) and fibroblast growth factor 19 (FGF19) among patients with IBS‐D, IBS‐C and healthy controls and to determine accurate, cost‐effective biomarkers for clinically relevant diarrhoea and constipation.MethodsWe assessed daily stool frequency and consistency (Bristol Stool Form Scale) from validated bowel diaries, 48 hours total and individual faecal bile acids, 48 hours faecal fat and weight, fasting serum C4 and FGF19, and colonic transit by scintigraphy from healthy volunteers (HV) and patients with IBS‐D and IBS‐C (Rome III criteria). We utilised multivariate logistic regression to determine biomarkers of clinically significant diarrhoea or constipation based on stool frequency, consistency and weight.ResultsAmong the 126 HV (44M/82F, 37.5 ± 10.9 years [SD]), 64 IBS‐D (5M/59F, 41.9 ± 12.2 years), and 30 IBS‐C (0M/30F, 44.6 ± 10 years) patients, there were significant differences between all groups in stool weight, frequency, and consistency; in addition, there were differences in colonic transit at 48 hours, faecal fat, and total and individual faecal bile acids between IBS‐D and IBS‐C. Reduced total and primary faecal bile acids and increased faecal lithocholic acid were significant predictors of decreased faecal weight, frequency and consistency with AUC > 0.82 (sensitivity >76%, specificity >72%). Total and primary faecal bile acids and faecal fat were significant predictors of increased stool weight, frequency and consistency with AUC > 0.71 (sensitivity >55%, specificity >74%).The faecal parameters had a 11.5 positive likelihood ratio in predicting elevated faecal weight.ConclusionsFaecal bile acids and faecal fat are cost‐effective and accurate biomarkers associated with significant bowel dysfunction among IBS‐D and IBS‐C patients.

Abstract Background Nausea, vomiting, and constipation ( OIC ) are common adverse effects of acute or chronic opioid use. Naloxegol (25 mg) is an approved peripherally active mu‐opiate opioid receptor antagonist. Aim To compare the effects on pan‐gut transit of treatment with codeine, naloxegol, or combination in healthy volunteers. Methods We conducted a randomized, double‐blind, placebo‐controlled, single‐center, parallel‐group study in 72 healthy opioid‐naïve adults, randomized to: codeine (30 mg q.i.d.), naloxegol (25 mg daily), codeine and naloxegol, or matching placebo. During 3 days of treatment, we measured gastric emptying ( GE ) T 1/2 , colonic filling at 6 hours ( CF 6), colonic geometric center at 24 and 48 hours, and ascending colon emptying ( ACE ) T 1/2 . Key Results Participants were 59.7% women, median BMI 25.0 kg/m 2 , and median age 33.8 years. Codeine significantly retarded GE T 1/2, CF 6, overall colonic transit, and ACE T 1/2 . There was significant difference ( P = .026) in GE T 1/2 between codeine (144.0 min [ IQR 110.5‐238.6]) and naloxegol (95.5 min [89.1‐135.4]). There was a significant overall group difference in CF 6 ( P = .023), with significant difference ( P = .019) between codeine (11.0% [0.0‐45.0]) and naloxegol (51% [18.8‐76.2]). However, no significant differences were found between codeine‐treated participants concomitantly receiving placebo or naloxegol. Conclusions and Inferences Short‐term administration of naloxegol (25 mg) in healthy, opioid‐naïve volunteers does not reverse the retardation of gastric, small bowel, or colonic transit induced by acute administration of codeine. Further studies with naloxegol at higher dose are warranted to assess the ability to reverse the retardation of transit caused by acute administration of codeine in opioid‐naïve subjects.