Zinsmeister, Alan R.

AbstractBackgroundNausea and vomiting are thought to result from upper gastrointestinal dysfunctions. Our clinical observations led to the hypothesis that colonic motor dysfunction is associated with nausea and vomiting.MethodsWe reviewed electronic medical records (EMR) of 149 patients presenting with complaints of nausea and/or vomiting in a tertiary gastroenterology practice to investigate the association with disorders of colonic motor or evacuation disorders. We extracted demographics, gastric emptying (GEin 149) and colonic transit (CTin 138) of solids, ascending colon emptying half‐time (ACt1/2), rectal evacuation by anorectal manometry (ARM) in 91 and balloon expulsion test (BE) in 55 patients. We estimated the proportions with delayedGEorCT, based on the 5th percentile ofGE(in 319) andCTin 220 healthy volunteers using same method.Key ResultsAmong 11 patients with nausea and/or vomiting with onlyGEmeasured, five had delayed and six normalGE. Among the 149 patients, 77 (52%) patients had evacuation disorders, confirmed by objective tests in 68 patients, and clinical examination in nine patients. In the 138 patients with bothGEandCTmeasured, 106 (76%) had both normalGEandCT, 11 (8%) only delayedGE, 16 (11%) normalGEwith delayedCT, and five (3%) delayedGEandCT. Among 21 patients (15%) with delayedCT, nine had slowACt1/2and 12 evacuation disorder.Conclusions & InferencesIn patients with chronic nausea and/or vomiting in gastroenterology practice, evaluation of colonic motility and rectal evacuation should be considered, since about half the patients have abnormal functions that conceivably contribute to the presenting nausea and/or vomiting.

The contribution of elevated glucagon-like peptide 1 (GLP-1) to postprandial glucose metabolism after Roux-en-Y gastric bypass (RYGB) has been the subject of uncertainty. We used exendin-9,39, a competitive antagonist of GLP-1, to examine glucose metabolism, islet hormone secretion, and gastrointestinal transit in subjects after RYGB and in matched control subjects. Subjects were studied in the presence or absence of exendin-9,39 infused at 300 pmol/kg/min. Exendin-9,39 resulted in an increase in integrated postprandial glucose concentrations post-RYGB (3.6 ± 0.5 vs. 2.0 ± 0.4 mol/6 h, P = 0.001). Exendin-9,39 decreased insulin concentrations (12.3 ± 2.2 vs. 18.1 ± 3.1 nmol/6 h, P = 0.002) and the β-cell response to glucose (ϕTotal, 13 ± 1 vs. 11 ± 1 × 10−9 min−1, P = 0.01) but did not alter the disposition index (DI). In control subjects, exendin-9,39 also increased glucose (2.2 ± 0.4 vs. 1.7 ± 0.3 mol/6 h, P = 0.03) without accompanying changes in insulin concentrations, resulting in an impaired DI. Post-RYGB, acceleration of stomach emptying during the first 30 min by exendin-9,39 did not alter meal appearance, and similarly, suppression of glucose production and stimulation of glucose disappearance were unaltered in RYGB subjects. These data indicate that endogenous GLP-1 has effects on glucose metabolism and on gastrointestinal motility years after RYGB. However, it remains uncertain whether this explains all of the changes after RYGB.

AbstractBackgroundLow basal lower esophageal sphincter (LES) pressure and transient LES relaxations are major causes of gastroesophageal reflux disease (GERD). Pumosetrag, a novel selective partial 5HT3 receptor agonist, showed a promising effect on reducing reflux events in health. We aimed to evaluate the effect of pumosetrag on changes in reflux episodes, lower esophageal sphincter pressure (LESP), and specific symptoms in patients with GERD receiving a refluxogenic meal.MethodsPatients with GERD, who developed heartburn and/or regurgitation after ingestion of a refluxogenic meal, were randomized to 1 of 3 dose levels of pumosetrag (0.2, 0.5, or 0.8 mg) or placebo. Before and after 7 days of treatment, patients underwent manometry, intraesophageal multichannel, intraluminal impedance and pH after a standard refluxogenic meal.Key ResultsA total of 223 patients with GERD [125 (56%) women, mean (SD) age = 36 (12) years] were enrolled. No overall treatment effects were detected for the total number of reflux episodes (acidic and weakly acidic) (p > 0.5); however, significant treatment effects (p < 0.05) on the number of acid reflux episodes were observed with lower values on pumosetrag 0.2 mg (10.8 ± 1.1), 0.5 mg (9.5 ± 1.1), and 0.8 mg (9.9 ± 1.1) compared with placebo (13.3 ± 1.1). Significant treatment effects (p < 0.05) were also observed for the percentage of time pH was <4, with less time for pumosetrag at 0.5 mg (10%) and 0.8 mg (10%) compared with placebo (16%).Conclusions & InferencesIn GERD, the partial 5HT3 agonist pumosetrag significantly reduced the rate of acid reflux events but did not result in a significant change in LESP or symptomatic improvement over a 1‐week treatment period.

Abstract Background Defecatory disorders can be diagnosed by rectal balloon expulsion ( BE ) and anorectal manometry, which are traditionally evaluated in the seated and left lateral ( LL ) positions, respectively. The aims of this study were to compare BE in the LL and seated positions and to compare anorectal manometric parameters to BE performed in the seated and LL positions. Methods 220 women [healthy (62), chronic constipation (158)] had anorectal high‐resolution manometry and BE , summarized by time required (seated position, normal ≤60 s) or external traction to facilitate expulsion ( LL position, normal ≤100 g). Key Results Balloon expulsion results in both positions were either concordant [normal (141) or abnormal (32)] or discordant [only LL abnormal (30), only seated abnormal (17)]. There was modest agreement [κ = 0.44 (95% CI 0.30–0.57)] between seated and LL BE . Compared with subjects with normal BE in both positions, anal pressure during simulated evacuation ( SE ) was higher, and the rectoanal gradient (rectal‐anal pressure) during SE was more negative in the other 3 categories (i.e., abnormal LL only, abnormal seated only, and both abnormal). High anal pressure during SE ( OR = 1.02, 95% CI 1.00–1.04) and high rectal sensory threshold for desire to defecate ( OR = 1.01, 95% CI 1.00–1.02) were associated with increased risk of abnormal BE in both positions, whereas high rectal pressure during SE ( OR = 0.96, 95% CI 0.93–0.98) was associated with lower risk. Conclusions & Inferences There is modest agreement between rectal BE in LL and seated positions. In addition to abnormal seated BE , which is considered indicative of pelvic floor dysfunction, high resolution manometry findings suggest that even some patients with abnormal BE in the LL position have pelvic floor dysfunction.

Exendin-(9,39) is a competitive antagonist of glucagon-like peptide-1 (GLP-1) at its receptor. However, it is unclear if it has direct and unique effects of its own. We tested the hypothesis that exendin-(9,39) and GLP-1-(9,36)amide have direct effects on hormone secretion and β-cell function as well as glucose metabolism in healthy subjects. Glucose containing [3-3H]glucose was infused to mimic the systemic appearance of glucose after a meal. Saline, GLP-1-(9,36)amide, or exendin-(9,39) at 30 pmol/kg/min (Ex 30) or 300 pmol/kg/min (Ex 300) were infused in random order on separate days. Integrated glucose concentrations were slightly but significantly increased by exendin-(9,39) (365 ± 43 vs. 383 ± 35 vs. 492 ± 49 vs. 337 ± 50 mmol per 6 h, saline, Ex 30, Ex 300, and GLP-1-[9,36]amide, respectively; P = 0.05). Insulin secretion did not differ among groups. However, insulin action was lowered by exendin-(9,39) (25 ± 4 vs. 20 ± 4 vs. 18 ± 3 vs. 21 ± 4 10−4 dL/kg[min per μU/mL]; P = 0.02), resulting in a lower disposition index (DI) during exendin-(9,39) infusion (1,118 ± 118 vs. 816 ± 83 vs. 725 ± 127 vs. 955 ± 166 10−14 dL/kg/min2 per pmol/L; P = 0.003). Endogenous glucose production and glucose disappearance did not differ significantly among groups. We conclude that exendin-(9,39), but not GLP-1-(9,36)amide, decreases insulin action and DI in healthy humans.

Summary Background Daikenchuto, a Japanese herbal medicine used for post‐operative ileus and constipation, dose dependently stimulates gastrointestinal ( GI ) motility and decreases rectal compliance and sensation. Effects of TU ‐100 (commercial form of daikenchuto) in adults with constipation are unknown. Aim To compare the effects of oral TU ‐100, 2.5 g t.d.s. or 5 g t.d.s. and placebo t.d.s. on GI and colonic transit ( CT ), rectal compliance ( RC ) and sensation thresholds ( RST ), anal sphincter pressures ( ASP ) and bowel function in female patients with functional constipation ( FC ). Methods We conducted a single‐centre, randomised, parallel‐group, double‐blind, pharmacodynamic study; 45 female patients with FC without evidence of rectal evacuation disorder were assigned to 28 days' treatment with oral placebo or TU ‐100 (Tsumura USA, Princeton, NJ, USA). Demographic data and CT were measured at baseline and randomisation stratified by baseline CT (GC> or <1.9) and by BMI (<25 or ≥25 kg/m 2 ). At the end of treatment period, we measured GI and CT by scintigraphy, RST and RC by barostat, ASP by manometry, psychosensory sensations, bowel function by daily diary and quality of life ( QOL ). The study had power to detect effect sizes of 33% ( CT ), 40% ( RC ) and 46% ( RST ). Statistical analysis included BMI as covariate. Results TU ‐100 had no significant effects on GI or CT , RC , ASP , recto‐anal pressure difference, or RST . The 5 g t.d.s./day dose was associated with lower RST for first sensation and gas (unadjusted P : 0.045 and 0.024 respectively). There were no treatment effects on psychosensory symptoms, stool frequency, stool consistency or QOL . Conclusion Mechanisms underlying the observed clinical benefit of TU ‐100 remain unclear ( ClinicalTrials.gov NCT01139216).

AbstractBackgroundFunctional GI syndromes are known to be very prevalent, but this may be linked to unrecognized medications use. We aimed to estimate the prevalence of PPI, antidepressant, and narcotic use in the general population, and to evaluate the association between each medication and functional GI syndromes adjusting for potential confounders.MethodsIn 2008 and 2009, newly revised versions of a validated bowel disease questionnaire were mailed to a community‐based cohort (total mailed = 8006) of Olmsted County, MN residents; 3831 returned the questionnaire (response rate = 48.0%). Medication usage, specifically PPIs, narcotics, and antidepressants in the last year, was elicited via three separate questions on the questionnaire. The association between each medication and GI symptom complexes was assessed using multiple variable logistic regression models.Key ResultsA total of 3515 of the respondents (92%) had complete data (mean age: 61 ± 15; 54% female). The overall proportion reporting PPI use was 20% (95% CI: 19, 22), narcotic use 12% (95% CI: 11, 13), and antidepressant use 15% (95% CI: 14, 16). PPI use was significantly associated with IBS status (OR = 1.4, 95% CI 1.1, 1.7) as well as with GERD (OR = 3.5, 95% CI 2.7, 4.4) and dyspepsia (OR = 2.0, 95% CI 1.5, 2.7). The association of PPI use with IBS was not explained by coexistent GERD or dyspepsia. Antidepressant use was significantly associated only with bloating (OR = 1.6, 1.1, 2.2).Conclusions & InferencesSome medications that may alter intestinal transit or bowel flora are commonly utilized by the general population, and PPI use appears to be linked to IBS.

Genetic variations in metabolism of endocannabinoids and in CNR1 (gene for cannabinoid 1 receptor) are associated with symptom phenotype, colonic transit, and left colon motility in irritable bowel syndrome (IBS). Our aim was to evaluate associations between two variations in CNR1 genotype (rs806378 and [AAT]n triplets) with symptom phenotype, small bowel and colonic transit, and rectal sensations in 455 patients with IBS and 228 healthy controls. Small bowel and colonic transit were measured by scintigraphy, rectal sensation by isobaric distensions. Associations with genotype were assessed by χ2test (symptom phenotype) and ANCOVA (quantitative traits) based on a dominant genetic model. Significant association of CNR1 rs806378 (but not CNR1 [AAT]n) genotype and symptom phenotype was observed (χ2P = 0.028). There was significant association of CNR1 rs806378 ( P = 0.014; CC vs. CT/TT) with colonic transit in IBS-diarrhea (IBS-D) group; the TT group had the fastest colonic transit at 24 and 48 h. There was significant overall association of CNR1 rs806378 with sensation rating of gas ( P = 0.025), but not pain; the strongest associations for gas ratings were in IBS-D ( P = 0.002) and IBS-alternating ( P = 0.025) subgroups. For CNR1 (AAT)n, gene-by-phenotype interactions were observed for colonic transit at 24 ( P = 0.06) and 48 h ( P = 0.002) and gas ( P = 0.046, highest for IBS-D, P = 0.034), but not pain sensation; the strongest association with transit was in controls, not in IBS. These data support the hypothesis that cannabinoid receptors may play a role in control of colonic transit and sensation in humans and deserve further study as potential mediators or therapeutic targets in lower functional gastrointestinal disorders.

We designed an experiment to examine the effect of bile acid sequestration with Colesevelam on fasting and postprandial glucose metabolism in type 2 diabetes. To do so, we tested the hypothesis that Colesevelam increases the disposition index (DI), and this increase is associated with increased glucagon-like peptide-1 (GLP-1) concentrations. Thirty-eight subjects on metformin monotherapy were studied using a double-blind, placebo-controlled, parallel-group design. Subjects were studied before and after 12 weeks of Colesevelam or placebo using a labeled triple-tracer mixed meal to measure the rate of meal appearance (Meal Ra), endogenous glucose production (EGP), and glucose disappearance (Rd). Insulin sensitivity and β-cell responsivity indices were estimated using the oral minimal model and then used to calculate DI. Therapy with Colesevelam was associated with a decrease in fasting (7.0 ± 0.2 vs. 6.6 ± 0.2 mmol/L; P = 0.004) and postprandial glucose concentrations (3,145 ± 138 vs. 2,896 ± 127 mmol/6 h; P = 0.01) in the absence of a change in insulin concentrations. Minimal model–derived indices of insulin secretion and action were unchanged. Postprandial GLP-1 concentrations were not altered by Colesevelam. Although EGP and Rd were unchanged, integrated Meal Ra was decreased by Colesevelam (5,191 ± 204 vs. 5,817 ± 204 μmol/kg/6 h; P = 0.04), suggesting increased splanchnic sequestration of meal-derived glucose.

Patients with irritable bowel syndrome (IBS) with diarrhea (IBS-D) carrying human leukocyte antigen (HLA)-DQ2/8 genotypes benefit from gluten withdrawal. Our objective was to compare gastrointestinal barrier function, mucosal inflammation, and transit in nonceliac IBS-D patients and assess association with HLA-DQ2/8 status. In 45 IBS-D patients who were naive to prior exclusion of dietary gluten, we measured small bowel (SB) and colonic mucosal permeability by cumulative urinary lactulose and mannitol excretion (0–2 h for SB and 8–24 h for colon), inflammation on duodenal and rectosigmoid mucosal biopsies (obtained in 28 of 45 patients), tight junction (TJ) protein mRNA and protein expression in SB and rectosigmoid mucosa, and gastrointestinal and colonic transit by validated scintigraphy. SB mucosal biopsies were stained with hematoxylin-eosin to assess villi and intraepithelial lymphocytes, and immunohistochemistry was used to assess CD3, CD8, tryptase, and zonula occludens 1 (ZO-1); colonic biopsy intraepithelial lymphocytes were quantitated. Associations of HLA-DQ were assessed using Wilcoxon's rank-sum test. Relative to healthy control data, we observed a significant increase in SB permeability ( P < 0.001), a borderline increase in colonic permeability ( P = 0.10), and a decrease in TJ mRNA expression in rectosigmoid mucosa in IBS-D. In HLA-DQ2/8-positive patients, ZO-1 protein expression in the rectosigmoid mucosa was reduced compared with that in HLA-DQ2/8-negative patients and colonic transit was slower than in HLA-DQ2/8-negative patients. No other associations with HLA genotype were identified. There is abnormal barrier function (increased SB permeability and reduced mRNA expression of TJ proteins) in IBS-D relative to health that may be, in part, related to immunogenotype, given reduced ZO-1 protein expression in rectosigmoid mucosa in HLA-DQ2/8-positive relative to HLA-DQ2/8-negative patients.