Performance characteristics of scintigraphic colon transit measurement in health and irritable bowel syndrome and relationship to bowel functions

Additional criteria on scintigraphic testing for diagnosis of rapid colonic transit in patients with chronic diarrhea

BACKGROUND

Colonic transit (CT) measured by validated scintigraphy using 111In-labeled activated charcoal particles is summarized using geometric center (GC) of isotopic distribution in four colonic regions and stool at 24 and 48 h. Diagnosis of rapid CT is currently based on GC24 ≥4.4 in females and >4.7 in males, which lack sensitivity. Our aim was to evaluate, in patients with chronic diarrhea with normal CT by GC24 and GC48, the diagnostic utility of CT change (∆GC) relative to sex-matched normal values.

METHODS

We evaluated two adult patient cohorts: 701 clinical patients (1994-2023) with chronic diarrhea and 76 research participants with irritable bowel syndrome with diarrhea (N = 63) or bile acid diarrhea (BAD, N = 13). Results of ∆GC were compared to 220 healthy controls' 95th percentiles (%ile) (≥2.0 females and ≥2.2 males). In the research cohort, we also analyzed (Spearman correlation) colonic ∆GC with ascending colon emptying T1/2 (AC T1/2), average stool frequency and consistency based on a daily diary, total fecal bile acid (BA) concentration, and % primary BA in a single stool sample.

KEY RESULTS

Among 701 clinical patients with normal GC24, 160 (22.3%) had rapid CT based on ∆GC 95th %ile in health. Among 76 research participants, an additional 20.6% IBS-D and 23% BAD had rapid CT ∆GC. Younger age and absence of diabetes mellitus were predictive of rapid ∆GC. ∆GC significantly correlated with AC T1/2 and with fecal BA.

CONCLUSIONS & INFERENCES

∆GC identified an additional 21%-23% patients with rapid colonic transit among patients with diarrhea and normal GC24.

Prevalence and determinants of postprandial diarrhea in a tertiary care center

BACKGROUND AND AIMS

Postprandial diarrhea (PPD) is commonly seen in patients with disorders of gut-brain interaction (DGBI), but the factors associated with it have not been well studied. In this study, we aim to study the burden, impact, and predictors of PPD using a clinical cohort of DGBI patients.

METHODS

This study included patients with chronic diarrhea fulfilling ROME IV criteria for irritable bowel syndrome (IBS) or functional diarrhea (FDiarr). PPD was defined as patients reporting mushy/watery stools following meals ≥30% of the time in the last 3 months using a ROME IV question on PPD. Age, sex, and BMI, the severity of diarrhea, abdominal pain, depression, anxiety, somatization, and quality of life were assessed using validated measures. Person's chi-square test and Student's t-test were used to compare variables. A multiple linear regression model with backward elimination was done to determine predictors of PPD severity.

KEY RESULTS

Of 213 eligible patients, more than three-fourth of patients (75.6%) had PPD. Women (79.0%, p = 0.037), patients with ROME IV diagnosis of IBS-D (90.5%, p = 0.002), and functional dyspepsia (83.2%, p = 0.014), and those with a history of cholecystectomy (CCY) (95.5%, p = 0.022) were more likely to report PPD. PPD patients experienced more severe abdominal pain, diarrhea, and decreased quality of life (QoL) but showed no significant difference in BMI, anxiety, depression, sleep, or somatization. In our regression model, female sex and history of CCY were independent predictors of PPD.

CONCLUSIONS AND INFERENCES

PPD is frequently reported among chronic diarrhea patients and is associated with more severe GI symptoms and decreased QoL. Female sex and CCY predict PPD, while psychological factors do not.

Assessment of Small-bowel and Colonic Transit on Routine Gastric Emptying Scintigraphy: Establishment of Reference Values

Purpose of the Study

The primary objective was to establish the reference values for small-bowel and colonic transit within the context of the routine standard solid meal gastric emptying scintigraphy (GES). The secondary objective was to compare the small-bowel and colonic transit between the anterior view and geometric mean methods.

Materials and Methods

Twenty-nine healthy controls underwent routine GES, with additional imaging at 24 h if feasible. Small-bowel transit was assessed using the index of small-bowel transit (ISBT), calculated as the ratio of terminal ileal reservoir counts to total abdominal counts at 4 h. Colonic transit was evaluated using the colonic geometric center (CGC) by dividing the large bowel into four segments, with an additional fifth segment accounting for the eliminated counts. Reference values were established based on the fifth percentile or mean ± 1.96 standard deviations. Rapid small-bowel transit was visually determined. Paired Samples t-test or Wilcoxon signed-rank test, as applicable, was used to compare the small-bowel and colonic transit between the anterior view and geometric mean methods. For comparing small-bowel and colonic transit between females and males, the Independent samples t-test or Mann-Whitney U-test was applied, as appropriate. The correlation between age and small-bowel and colonic transit was assessed using Spearman's rank correlation analysis.

Results

The reference value for small-bowel transit using the geometric mean method was established as ISBT >37% at 4 h, whereas rapid small-bowel transit was defined as the first visualization of activity in the cecum-ascending colon within 2 h. For colonic transit, the reference range was established as CGC 2.8-4.4 at 24 h. Comparing the anterior view and geometric mean methods, there were no significant differences in ISBT and CGC values (P ≥ 0.125). Gender did not affect small-bowel and colonic transit in both methods (P ≥ 0.378), and age showed no significant correlations (P ≥ 0.053).

Conclusion

This study determined the reference values for small-bowel and colonic transit in the Indian population using routine GES, avoiding the need for additional complex procedures. The results may be generalized to the Indian population, emphasizing the importance of assessing small-bowel and colonic transit in patients with normal gastric emptying parameters to enhance gastrointestinal transit evaluation.

Dietary fibres and IBS: translating functional characteristics to clinical value in the era of personalised medicine

Clinical guidelines in the use of fibre supplementation for patients with IBS provide one-size-fits-all advice, which has limited value. This narrative review addresses data and concepts around the functional characteristics of fibre and subsequent physiological responses induced in patients with IBS with a view to exploring the application of such knowledge to the precision use of fibre supplements. The key findings are that first, individual fibres elicit highly distinct physiological responses that are associated with their functional characteristics rather than solubility. Second, the current evidence has focused on the use of fibres as a monotherapy for IBS symptoms overall without attempting to exploit these functional characteristics to elicit specific, symptom-targeted effects, or to use fibre types as adjunctive therapies. Personalisation of fibre therapies can therefore target several therapeutic goals. Proposed goals include achieving normalisation of bowel habit, modulation of gut microbiota function towards health and correction of microbial effects of other dietary therapies. To put into perspective, bulking fibres that are minimally fermented can offer utility in modulating indices of bowel habit; slowly fermented fibres may enhance the activities of the gut microbiota; and the combination of both fibres may potentially offer both benefits while optimising the activities of the microbiota throughout the different regions of the colon. In conclusion, understanding the GI responses to specific fibres, particularly in relation to the physiology of the individual, will be the future for personalising fibre therapy for enhancing the personalised management of patients with IBS.

In vivo models to evaluate ingestible devices: Present status and current trends

Evaluation of orally ingestible devices is critical to optimize their performance early in development. Using animals as a pre-clinical tool can provide useful information on functionality, yet it is important to recognize that animal gastrointestinal physiology, pathophysiology and anatomy can differ to that in humans and that the most suitable species needs to be selected to inform the evaluation. There has been a move towards in vitro and in silico models rather than animal models in line with the 3Rs (Replacement, Reduction and Refinement) as well as the better control and reproducibility associated with these systems. However, there are still instances where animal models provide the greatest understanding. This paper provides an overview of key aspects of human gastrointestinal anatomy and physiology and compares parameters to those reported in animal species. The value of each species can be determined based upon the parameter of interest from the ingested device when considering the use of pre-clinical animal testing.

A Novel Noninvasive Method for Quantitative Detection of Colonic Dysmotility Using Real-Time Ultrasonography

INTRODUCTION

Colonic motility disorders are a frequent clinical problem caused by various drugs and diseases. However, the etiology of colonic dysmotility is often unclear due to the lack of in vivo methods, including rapid dynamic assessment.

OBJECTIVES

The aim of this study was to establish a novel quantitative method to objectively assess colonic motility using ultrasonography.

METHODS

We applied echocardiographic speckle tracking-based strain imaging to analyze murine colonic motility. A trace line was placed on the boundary between the proximal wall of the colon and the inner cavity to analyze colonic wall displacement and strain rate. Locomotion activities of the colonic wall were used to quantify colonic motility via ultrasonography.

RESULTS

We found that ultrasonography can quantitatively detect a decrease in colonic motility induced by loperamide, an antidiarrheal drug. These quantitative data were consistent with the imaging findings of colonic peristalsis and colon transit time. Additionally, ultrasonography also revealed changes in colonic motility over short intervals. Furthermore, we have shown that ultrasonography can quantitatively and noninvasively detect colonic dysmotility and hypervascularity of the colonic wall in colitis mice.

CONCLUSIONS

These findings suggest that ultrasonography is a useful in vivo method for objectively monitoring changes in colonic motility caused by drugs and diseases.

Pectin based multi-particulate carriers for colon-specific delivery of therapeutic agents

In case of colon-specific delivery of therapeutic agents through oral route, microbial/enzyme-triggered release approach has several advantages over other approaches due to unique microbial ecosystem in the colon. Multiple-unit carriers have an edge over single-unit carriers for this purpose. Among different materials/polymers explored, pectin appears as a promising biopolymer to construct microbial-triggered colon-specific carriers. Pectin is specifically degraded by colonic enzymes but insusceptible to upper gastro-intestinal enzymes. In this article, utilization of pectin solely or in combination with other polymers and/or colonic-delivery approaches is critically discussed in detail in the context of multi-particulate systems. Several studies showed that pectin-based carriers can prevent the release of payload in the stomach but start to release in the intestine. Hence, pectin alone may construct delayed release formulation but may not be sufficient for effective colon-targeting. On the other hand, combination of pectin with other materials/polymers (e.g., chitosan and Eudragit® S-100) has demonstrated huge promise for colon-specific release of payload. Hence, smartly designed pectin-based multi-particulate carriers, especially in combination with other polymers and/or colon-targeting approaches (e.g., microbial-triggered + pH-triggered or microbial-triggered + pH-triggered + time-release or microbial-triggered + pH-triggered + pressure-based), can be successful colon-specific delivery systems. However, more clinical trials are necessary to bring this idea from bench to bedside.

Prevention of loperamide induced constipation in mice by KGM and the mechanisms of different gastrointestinal tract microbiota regulation

Constipation is one of the most prevalent gastrointestinal tract diseases. Konjac glucomannan (KGM) dietotherapy can effectively relieve the clinical symptoms of patients with constipation. However, the causal relationship among KGM, constipation and different gastrointestinal microbiome (i.e., the stomach {St}, small intestine {S}, and large intestine {L}) remains poorly understood. In this study, constipated mice were treated with KGM (75, 150, 300 mg/kg bw). Results showed that KGM treatment improved the general physiological state, fecal character, small intestinal propulsive rate, gastric emptying rate, MTL and AchE activities, ET-1, 5-HT, and NO levels, and SCFA concentrations. KGM in the diets of constipated mice reduced the diversity of St and S microbiota, while increased those in the L. The KGM intervention regulated the microbiota profile, which afterwards was closer to the normal mouse group: confirmation was provided by different changes of bacteria like Lactobacillus, Bifidobacterium and Allobaculum spp et al.

Gastrointestinal motility evaluation in children with orthostatic intolerance: Mayo Clinic experience

OBJECTIVE

Orthostatic intolerance (OI) and autonomic dysfunction (AD) are common in adolescents and young adults. Patients experience multisystem symptoms including gastrointestinal (GI), postural orthostatic tachycardia syndrome (POTS), orthostatic hypotension (OH), or only symptoms of OI (SOI) without significant findings on 70-degree head-up tilt testing (HUT). We hypothesize that patients with POTS, OH, and SOI show differences in GI symptoms and motility test and that heart rate (HR) changes on HUT predict severity of GI dysmotility.

STUDY DESIGN

From medical records of patients (<18 years) with OI, we collected demographics, presenting symptoms, GI manifestations, and GI motility testing. Data were compared between the 3 groups (POTS, OH, and SOI). We assessed changes in HR on HUT with changes on GI motility evaluation.

RESULTS

Two hundred twenty-nine patients were included (73% females). Abdominal pain (65%), nausea (49%), vomiting (18%), and constipation (24%) were the most common GI symptoms. In patients who had motility evaluation, there were 27% (53/193) with delayed gastric emptying (GE) at 4 hours, 35% (32/92) with delayed colonic transit (CT), 55% (17/31) with reduced gastric accommodation (GA), and 75% (21/28) with dyssynergic defecation (DD). Among 100 POTS, 34 OH, and 95 SOI patients, no significant differences in GI symptoms or motility tests were identified and HR changes on HUT were not associated with changes on motility tests.

CONCLUSION

GI symptoms are frequent in adolescents with OI and are associated with delayed GE, reduced GA, delayed CT, and presence of DD.

Clinical features and disturbances of gastrointestinal transit in patients with rapid gastric emptying

AIMS

Some patients with upper gastrointestinal symptoms have rapid gastric emptying (GE). We aimed to compare patients with normal and rapid GE and to identify phenotypes among patients with rapid GE.

METHODS

Among 2798 patients who underwent GE scintigraphy, we compared patients with normal and rapid GE and separately, patients with rapid GE at 1 hour (GE1), 2 hours (GE2), or both (GE12).

RESULTS

In 2798 patients, GE was normal (74%), delayed (18%), or rapid (8%). Among 211 patients with rapid GE, patterns were rapid GE1 (48%), 2 hours (17%), or 1 and 2 hours (35%); 42 (20%) had diseases that explain rapid GE. A combination of upper and lower gastrointestinal symptoms (54%) was more common that isolated upper (17%) or lower (28%) gastrointestinal symptoms (P < .001). Constipation was more prevalent in patients with rapid GE 2 (72%) than rapid GE 1 (47%) or rapid GE12 hours (67%) (P < .05). Among 179 diabetes mellitus (DM) patients, 15% had rapid GE, which was not associated with the DM phenotype. By multivariable analysis, insulin therapy (odds ratio [OR], 0.36; 95% confidence interval [CI], 0.15-0.88), and weight loss (OR, 0.10; 95% CI, 0.01-0.78) were associated with a lower risk of rapid than normal GE in DM.

CONCLUSIONS

Eight percent of patients undergoing scintigraphy had rapid GE, which is most frequently associated with upper and lower gastrointestinal symptoms; constipation is common. Insulin therapy and weight loss were associated with a lower risk of rapid than normal GE in DM patients.

Imaging Measurement of Whole Gut Transit Time in Paediatric and Adult Functional Gastrointestinal Disorders: A Systematic Review and Narrative Synthesis

BACKGROUND

functional gastrointestinal disorders (FGID) are common conditions in children and adults, often associated with abnormalities of whole gut transit. Currently, transit tests can be performed using several imaging methods, including tracking of radiopaque markers, gamma scintigraphy with the use of radioisotopes, magnetic tracking methods, tracking of movement of wireless motility capsules, and emerging magnetic resonance imaging (MRI) approaches.

OBJECTIVES

to review recent literature on diagnostic imaging techniques used to investigate whole gut transit in FGIDs.

METHODS

a systematic review was carried out. The different techniques are described briefly, with particular emphasis on contemporary literature and new developments, particularly in the field of MRI.

CONCLUSIONS

emerging MRI capsule marker methods are promising new tools to study whole gut transit in FGIDs.

Analysis of Fecal Primary Bile Acids Detects Increased Stool Weight and Colonic Transit in Patients With Chronic Functional Diarrhea

BACKGROUND & AIMS

Patients with bile acid diarrhea (BAD) are identified based on increased levels of BAs in fecal samples collected over a 48-hr period while on a 100-gram fat diet (48-hr BA), retention of 75Se-labeled homocholic acid taurine, or serum levels of C4 or FGF19. BAD increases fecal weight and colonic transit. We investigated whether results of tests for BAD associate with increased fecal weight and more rapid colonic transit over a 24- or 48-hr period in patients with irritable bowel syndrome with diarrhea (IBS-D). We also estimated the prevalence of increased 48-hr fecal BAs in patients with chronic diarrhea.

METHODS

We performed a retrospective study of 64 patients with IBS-D, 30 patients with IBS-constipation, 30 healthy volunteers (controls). We collected data on fecal weights (measured over a 48-hr period), colonic transit over a 24-hr period (measured by scintigraphy), and percentages of different BAs in stool samples. Colonic transit was measured as the geometric center (weighted average) of colonic counts on a scale of 1 (100% in ascending colon) to 5 (100% in stool). We performed area under the curve (AUC) analyses to assess the association between result of serum and stool tests and high fecal weight (>400g/48 hrs) or rapid colonic transit (>3.34, corresponding to isotope geometric center in sigmoid colon). We estimated the prevalence of increased 48-hr fecal BAs among 938 patients with chronic diarrhea.

RESULTS

Total fecal 48-hr BA alone, or in combination with percentage of primary fecal BAs, identified patients with increased fecal weight with an AUROC of 0.86. Percentage of primary fecal BA alone identified patients with increased fecal weight with an AUROC of 0.73. Total fecal 48-hr BA alone identified patients with increased colonic transit with an AUROC of 0.65 and percentage of primary fecal BA alone identified patients with increased colonic transit with an AUROC of 0.69; combined data on these features identified patients with increased colonic transit with an AUROC of 0.70. Serum level of C4 identified patients with increased colonic transit with an AUROC of 0.60. Primary BAs >10% identified patients with increased fecal weight (sensitivity 49% and specificity 91%) and rapid colonic transit (sensitivity 48% and specificity 87%). Among the patients with chronic diarrhea, 45.6% had fecal primary BAs >10% and 27% had increased total fecal BAs (>2337 μmol/48 hrs).

CONCLUSIONS

In a retrospective analysis of patients with IBS-D, we found percentage of primary BAs in fecal samples to provide an alternative to total fecal BAs in identification of patients with BAD or chronic diarrhea.

GI Motility Testing: Stomach, Small Bowel, and Colon

Symptoms of abdominal pain, nausea, vomiting, bloating, abdominal distention, diarrhea, and constipation are common and may relate to abnormalities in gastrointestinal motility. There are a number of different options to study gastrointestinal motility. This article reviews novel and standard motility tests available in the stomach, small bowel, and colon. The indications for testing, technical details, advantages, and disadvantages of each test will be summarized.

Bile and fat excretion are biomarkers of clinically significant diarrhoea and constipation in irritable bowel syndrome

BACKGROUND

Biomarkers 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.

AIM

To 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.

METHODS

We 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.

RESULTS

Among 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.

CONCLUSIONS

Faecal bile acids and faecal fat are cost-effective and accurate biomarkers associated with significant bowel dysfunction among IBS-D and IBS-C patients.

Audit of the diagnosis of rectal evacuation disorders in chronic constipation

BACKGROUND

Balloon expulsion test (BET) and high-resolution anorectal manometry (HRM) are used in diagnosis of rectal evacuation disorders (REDs); their performance characteristics are suboptimal.

METHODS

We audited records of 449 consecutive patients with chronic constipation (CC). We documented anal sphincter tone and contraction, puborectalis tenderness, and perineal descent on digital rectal exam (DRE); maximum resting and squeeze pressures, and rectoanal pressure gradient on HRM; weight or time to balloon expulsion; colonic transit, and area of rectal area on radiograph (RASF). We based the diagnosis of RED on ≥2 abnormalities on both DRE and HRM, excluding results of BET, as the performance of BET is being investigated. Results of RED vs non-RED and results obtained using tbBET vs wbBET groups were compared. We used multivariate logistic regressions to identify predictors of RED using different diagnostic modalities.

KEY RESULTS

Among 449 individuals, 276 were included (74 RED and 202 non-RED). Predominant exclusions were for no HRM (n = 79) or use of low resolution anorectal manometry (n = 77). Logistic regression models for abnormal tbBET showed time >60 seconds, RASF and age-predicted RED. For tbBET, the current cutoff of 60 seconds had sensitivity of 39.0% and specificity 93.0% to diagnose RED; on the other hand, applying the cutoff at 22 seconds, the sensitivity was 77.8% and specificity 69.8%.

CONCLUSIONS & INFERENCES

The clinical diagnosis of RED in patients with CC is achieved with combination of DRE, HRM and an optimized, time-based BET. Prospective studies are necessary to confirm the proposed 22 second cutoff for tbBET.

Demonstration of differences in colonic volumes, transit, chyme consistency, and response to psyllium between healthy and constipated subjects using magnetic resonance imaging

BACKGROUND

In functional gastrointestinal disorders a lack of objective biomarkers limits evaluation of underlying mechanisms. We aimed to demonstrate the utility of magnetic resonance imaging for this task using psyllium, an effective constipation treatment, in patients and controls.

METHODS

Two crossover studies: (i) adults without constipation (controls, n = 9) took three treatments in randomized order for 6 days - maltodextrin (placebo), psyllium 3.5 g t.d.s and 7 g t.d.s., (ii) adults with chronic constipation (patients, n = 20) took placebo and psyllium 7 g t.d.s. for 6 days. MRI was performed fasting and postprandially on day 6. Measurements included small bowel and ascending colon water content, colonic volume, transit time, and MR relaxometry (T1, T2) to assess colonic chyme. Stool water percentage was measured.

RESULTS

7 g psyllium t.d.s. increased fasting colonic volumes in controls from median 372 mL (IQR 284-601) to 578 mL (IQR 510-882), and in patients from median 831 mL (IQR 745-934) to 1104 mL (847-1316), P < .05. Mean postprandial small bowel water was higher in controls and patients after 7 g psyllium t.d.s. vs placebo. Whole gut transit was slower in patients than controls (P < .05). T1 of the descending colon chyme (fasting) was lower in patients (213 ms, 176-420) than controls (440 ms, 352-884, P < .05) on placebo, but increased by 7 g psyllium t.d.s. (590 ms, 446-1338), P < .001. Descending colon T1 correlated with baseline stool water content and stool frequency on treatment.

CONCLUSIONS AND INFERENCES

MRI measurements can objectively demonstrate the mode of action of therapy targeting intestinal fluid content in constipation.

Comparative Analysis of Ileal and Cecal Microbiota in Aged Rats

Background

Gut microbiota contributes to intestinal and immune homeostasis through host-microbiota interactions. Distribution of the gut microbiota differs according to the location in the gastrointestinal tract. Although the microbiota properties change with age, evidence for the regional difference of gut microbiota has been restricted to the young. The aim of this study is to compare the gut microbiota between terminal ileum and cecum of old rats.

Methods

We analyzed gut microbiome of luminal contents from ileum and cecum of 74-week-old and 2-year-old rats (corresponding to 60-year and 80-year-old of human age) by metagenome sequencing of 16S rRNA.

Results

Inter-individual variation (beta diversity) of microbiota was higher in ileum than in cecum. Conversely, alpha diversity of microbiota composition was higher in cecum than in ileum. Lactobacillaceae were more abundant in ileum compared to cecum while Ruminococcaceae and Lachnospiraceae were more enriched in cecum. The proportions of Deltaproteobacteria were increased in cecal microbiota of 2-year-old rats compared to 74-week-old rats.

Conclusions

Major regional distinctions of microbiota between ileum and cecum of old rats appear consistent with those of young rats. Age-related alterations of gut microbiota in old rats seem to occur in minor compositions.

Expert consensus document: Advances in the diagnosis and classification of gastric and intestinal motility disorders

Disturbances of gastric, intestinal and colonic motor and sensory functions affect a large proportion of the population worldwide, impair quality of life and cause considerable health-care costs. Assessment of gastrointestinal motility in these patients can serve to establish diagnosis and to guide therapy. Major advances in diagnostic techniques during the past 5-10 years have led to this update about indications for and selection and performance of currently available tests. As symptoms have poor concordance with gastrointestinal motor dysfunction, clinical motility testing is indicated in patients in whom there is no evidence of causative mucosal or structural diseases such as inflammatory or malignant disease. Transit tests using radiopaque markers, scintigraphy, breath tests and wireless motility capsules are noninvasive. Other tests of gastrointestinal contractility or sensation usually require intubation, typically represent second-line investigations limited to patients with severe symptoms and are performed at only specialized centres. This Consensus Statement details recommended tests as well as useful clinical alternatives for investigation of gastric, small bowel and colonic motility. The article provides recommendations on how to classify gastrointestinal motor disorders on the basis of test results and describes how test results guide treatment decisions.

Gut region influences the diversity and interactions of bacterial communities in pikas (Ochotona curzoniae and Ochotona daurica)

The mammalian microbial communities in the gastrointestinal tract (GIT) play important roles in host nutrition and health. However, we still lack an understanding of how these communities are organized across GIT in natural environments. Here, using 16S rRNA gene sequencing, we analyzed the bacterial community diversity, network interactions and ecosystem stability across five gut regions (mouth, stomach, small intestine, cecum and colon) emanating from two common pika species in China, including Plateau pikas (Ochotona curzoniae) inhabiting high-altitude regions, as well as Daurian pikas (O. daurica) occupying low-altitude areas. The relative abundances of dominant Bacteroidetes and Firmicutes exhibited an increasing trend from mouth to colon. Cecum and colon harbored higher bacterial diversity compared with other anatomical regions. Gut region significantly influenced the structure of bacterial communities in the GIT. Network analysis indicated that topological features showed marked variations among gut regions. Interestingly, the ecosystem stability of bacterial communities increased gradually from mouth to colon. Our results suggest that gut region influences the diversity, structure and network interactions of bacterial communities in pikas. For hindgut-fermenting herbivorous mammals, relatively higher bacterial diversity and ecosystem stability in the cecum may provide a favorable condition for the fermentation of indigestible plant polysaccharides.

Bile Acid Deficiency in a Subgroup of Patients With Irritable Bowel Syndrome With Constipation Based on Biomarkers in Serum and Fecal Samples

BACKGROUND & AIMS

Short-term administration of delayed-release chenodeoxycholic acid to patients with irritable bowel syndrome with constipation (IBS-C) accelerates colonic transit and reduces symptoms. A preliminary study has shown that patients with IBS-C have reduced levels of bile acids (BAs) in feces and reduced synthesis of BA. We compared the levels of primary and secondary BAs in fecal samples collected over a 48-hour period from patients with IBS-C on a diet that contained 100 g fat per day, and compared them with levels in samples from healthy volunteers (controls). We also examined the relationship between overall colonic transit and biomarkers of BAs in patients with IBS-C.

METHODS

We performed a retrospective study of 45 patients with IBS-C and 184 controls. For controls, we estimated the 10th percentile of fasting serum levels of 7α-hydroxy-4-cholesten-3-one (C4, n = 184) and 48-hour fecal BAs (n = 46), and the 90th percentile of the fasting serum level of fibroblast growth factor 19 (FGF19, n = 50). Colonic transit was measured in patients using a validated scintigraphic method. Data from patients with IBS-C were analyzed using Spearman correlations to determine the relationships among levels of C4, FGF19, fecal BAs, and colonic transit.

RESULTS

Among the patients with IBS-C, 2 of 45 had low serum levels of C4, 4 of 43 had increased serum levels of FGF19, and 6 of 39 had low levels of BAs in feces collected over 48 hours. Patients with IBS-C had a significant increase in the proportions of fecal lithocholic acid compared with controls (P = .04), and a decrease in deoxycholic acid compared with controls (P = .03). In patients with IBS-C, there were inverse relationships between serum levels of C4 and FGF19 and correlations among levels of 48-hour fecal BAs, colonic transit, and serum C4 and FGF19.

CONCLUSIONS

Approximately 15% of patients with IBS-C have reduced total BAs and level of deoxycholic acid in fecal samples collected over 48 hours on a 100 g fat diet. In these patients, lower levels of excretion of BAs into feces correlated with slower colonic transit.

Reproducibility of assessing fecal microbiota in chronic constipation

BACKGROUND

While limited data suggest that the fecal microbiota in healthy people is stable over time, the intraindividual variability of the fecal microbiota in constipated patients is unknown.

METHODS

This study evaluated the intraindividual reproducibility of fecal microbiota analyzed with 16S rRNA gene sequencing in two stool samples collected without and after a laxative, respectively, in 25 healthy people and 25 constipated women. Participants completed a food record for 3 d before the stool collection. Colonic transit was measured with scintigraphy.

KEY RESULTS

The constipated patients were older (48±15 vs 39±10 y, P=.02) than healthy participants but had a similar BMI. The total daily caloric intake was less (P=.005) in constipated (1265±350 kcal) than healthy participants (1597±402 kcal). Fourteen patients but only two controls (P<.005), had delayed colonic transit. For most measures of alpha (eg, Observed OTU number, Shannon index) and beta diversity (eg, Bray-Curtis dissimilarity, UniFrac, phyla level abundance), the ICCs between two stool samples were high, indicating moderate or strong agreement, and similar in healthy people and constipated patients. The ICC for the weighted UniFrac distance, which is weighted by abundance, was lower than its unweighted counterpart, indicating that the unweighted measure is more robust and reproducible.

CONCLUSIONS AND INFERENCES

The intraindividual reproducibility of fecal microbiota in constipated patients is high and comparable to healthy participants. For most purposes, evaluating the fecal microbiota in a single stool sample should generally suffice in adequately powered studies of healthy and constipated patients.

Established and emerging methods for assessment of small and large intestinal motility

BACKGROUND

Gastrointestinal symptoms are common in the general population and may originate from disturbances in gut motility. However, fundamental mechanistic understanding of motility remains inadequate, especially of the less accessible regions of the small bowel and colon. Hence, refinement and validation of objective methods to evaluate motility of the whole gut is important. Such techniques may be applied in clinical settings as diagnostic tools, in research to elucidate underlying mechanisms of diseases, and to evaluate how the gut responds to various drugs. A wide array of such methods exists; however, a limited number are used universally due to drawbacks like radiation exposure, lack of standardization, and difficulties interpreting data. In recent years, several new methods such as the 3D-Transit system and magnetic resonance imaging assessments on small bowel and colonic motility have emerged, with the advantages that they are less invasive, use no radiation, and provide much more detailed information.

PURPOSE

This review outlines well-established and emerging methods to evaluate small bowel and colonic motility in clinical settings and in research. The latter include the 3D-Transit system, magnetic resonance imaging assessments, and high-resolution manometry. Procedures, indications, and the relative strengths and weaknesses of each method are summarized.

A single-center, prospective, double-blind, sham-controlled, randomized study of the effect of a vibrating capsule on colonic transit in patients with chronic constipation

BACKGROUND

In an open-label study of 26 patients with IBS-C and chronic constipation, treatment with a vibrating (VIBRANT) capsule twice a week for 7.5 weeks resulted in 88.5% responders. Effects on colonic transit are unclear. We aimed to compare effects of VIBRANT and sham capsule treatment on colonic transit in patients with functional constipation.

METHODS

Patients with functional constipation (Rome III criteria) were randomized to VIBRANT or sham capsule treatment for 8 weeks and underwent scintigraphic colonic transit measurements during week 8. We estimated the overall rate of colonic transit from the slope of progression of colonic geometric center over 48 hours. The capsule was activated 8 hours after ingestion, and the vibration sequence included 240 cycles.

KEY RESULTS

There were no significant group differences in overall colonic transit [GC48, 2.76 (IQR 2.42-4.03) for sham group and 3.46 (2.55-4.61) for active treatment group (P=.13)]. Additionally, the progression of the isotope through the colon was numerically faster, though not significantly different (slope, P=.14) in the VIBRANT capsule group compared to the sham group. Three participants in the VIBRANT capsule group had accelerated colonic transit at 32 hours and faster colonic transit slope compared to the 95th percentile of the sham group.

CONCLUSIONS AND INFERENCES

Although there were no group differences between VIBRANT and sham capsule treatment on colonic transit, at least one (and possibly three) of 12 patients receiving the VIBRANT capsule had faster colonic transit. The vibration parameters to accelerate colonic transit in patients with functional constipation require further optimization.

Colonic Transit and Bile Acid Synthesis or Excretion in Patients With Irritable Bowel Syndrome-Diarrhea Without Bile Acid Malabsorption

BACKGROUND AND AIMS

Bile acids (BAs) are passively absorbed to a different extent along the mammalian colon, so that levels are lower in the feces than in proximal colon. Our aim was to explore associations among total, primary, and secretory BA in stool and colonic transit in patients with irritable bowel syndrome-diarrhea (IBS-D) without overt BA malabsorption (BAM).

METHODS

In a cross-sectional observational study of 116 patients with IBS-D recruited from local communities in Minnesota, we measured total and individual main fecal BA excretion, fecal fat and fecal weight over 48 hours, fasting serum levels of C4 (surrogate for BA synthesis), and overall colonic transit by scintigraphy (geometric center at 24 hours and 48 hours). Patients without overt BAM were assigned to groups based on total fecal BA level below 2337 μmol/48 hours (n = 86) or serum levels of C4 below 47.1 ng/mL (n = 91). We used Spearman correlations to test study hypotheses with correction for 14 correlations tested (P < .0036). Data from 30 healthy volunteers were used as control subjects.

RESULTS

Patients with IBS-D who had increased or normal total BA excretion in stool or BA synthesis had higher stool proportions of primary BAs (especially chenodeoxycholate), compared with healthy control subjects. In patients with IBS-D without overt BAM (normal 48-hour total fecal BA or serum C4), there were significant positive correlations between total fecal BA, fecal primary and secretory BA, fecal weight, and increased geometric center at 24 and 48 hours (P < .0036). Normal and slightly increased levels of total fecal BA have greatest effects on colonic transit at 48 hours.

CONCLUSIONS

In the absence of overt BAM, the total, primary, and secretory BAs in stool contribute to the acceleration of colonic transit and fecal weight in the diarrhea of patients with IBS-D.

Biomarkers as a diagnostic tool for irritable bowel syndrome: where are we?

Irritable bowel syndrome (IBS) is a common condition in clinical practice. There are currently no objective tests to rule in the disease, but rather tests to rule out other diseases. Biomarkers in IBS may provide the tools needed for diagnosis, prognosis and therapy. These include identification of differences in microbial composition, immune activation, bile acid composition, colonic transit, and alteration in sensation in subgroups of IBS patients. Areas covered: Studies included in our review were chosen based on a PubMed search for 'biomarkers' and 'IBS'. We have reviewed the literature on biomarkers to appraise their accuracy, validity and whether they are actionable. We have not covered genetic associations as biomarkers in this review. Expert commentary: There is significant promise in the usefulness of biomarkers for IBS. The most promising actionable biomarkers are markers of changes in bile acid balance, such as elevated bile acid in the stool, and altered colonic transit. However, there is also potential for microbial studies and mucosal proteases as future actionable biomarkers.

Rectal Gas Volume Measured by Computerized Tomography Identifies Evacuation Disorders in Patients With Constipation

BACKGROUND & AIMS

Approximately one third of patients who present to gastroenterology care with constipation have rectal evacuation disorders. We aimed to compare rectal gas volume, measured by computerized tomography (CT), in constipated patients with and without rectal evacuation disorders.

METHODS

In a retrospective study, we collected data from 1553 patients with constipation, evaluated over 20 years. We analyzed data from 141 patients evaluated by anorectal manometry, balloon expulsion tests, and colon transit tests, collecting records of abdominal and pelvic CT examinations. Patients were classified into 3 subgroups: those with rectal evacuation disorders, slow-transit constipation, or normal-transit constipation. Two observers used standard CT software to identify variable regions of interest on each cross-sectional CT image that contained rectum and measured areas of gas in each slice; they then summated entire volumes of rectal gas. For the 3 groups, we compared rectal gas volume, maximal rectal gas transaxial area (measured by CT), and area of rectal gas (vertical) on the 2-dimensional abdominal film (scout) using the Kruskal-Wallis test.

RESULTS

The intraclass correlation coefficient between 2 observers' measurements of rectal gas volume was 0.99 (P < .001). There were overall group differences in rectal gas volume and the maximal rectal gas transaxial area (both P < .001). The median rectal gas volume was higher in patients with rectal evacuation disorders (13.84 cm³) than in patients with slow-transit (2.51 cm³) or normal-transit constipation (1.33 cm³, both P < .05). Similarly, the area of rectal gas, which correlated with the maximal rectal gas transaxial area (Spearman correlation coefficient, 0.7; P < .001), showed overall 3-group differences (P = .033), with greater areas of rectal gas on the abdominal scout film in patients with rectal evacuation disorders than in those with normal-transit constipation.

CONCLUSIONS

In an analysis of patients with constipation, we found rectal gas volume, determined by abdominal CT imaging, to be greater in patients with than without rectal evacuation disorders.

Regional Colonic Transit Pattern Does Not Conclusively Identify Evacuation Disorders in Constipated Patients with Delayed Colonic Transit

Background/Aims

After exclusion of structural diseases, chronic constipation may be associated with normal or slow transit or rectal evacuation disorders. We evaluated: (1) clinical features and anorectal function, (2) difference of regional colonic transit according to the presence or absence of evacuation disorders, and (3) association of colonic transit with gender in patients with objectively slow colonic transit.

Methods

We reviewed electronic medical records of 1553 patients with constipation seen by one gastroenterologist from 1994–2015 at a tertiary medical center. We identified patients with slow colonic transit using scintigraphy. Evacuation disorders were identified on clinical examination or anorectal manometry. Colonic compliance and tone were measured in 29 patients. Statistical analysis was by the Mann-Whitney rank sum test.

Results

Of the 207 patients (155 females, mean age 41.3 ± 15.3 [SD] years), 113 had evacuation disorders (ED+ve) and 94 did not (ED−ve). There were no significant differences in colonic transit or gastric emptying between ED+ve or ED−ve; similarly, colonic compliance, tone and responses to neostigmine were not different in ED+ve and ED−ve. Conversely, there were significant differences by gender in patients with slow colonic transit: colonic transit, small bowel transit, and gastric emptying (all P < 0.005).

Conclusions

Delayed colonic transit does not exclude evacuation disorders in chronic constipation. In chronic constipation and objectively slow colonic transit, females had slower gastric, small bowel, and colonic transit than males.

Alterations of colonic function in the Winnie mouse model of spontaneous chronic colitis

The Winnie mouse, carrying a missense mutation in Muc2, is a model for chronic intestinal inflammation demonstrating symptoms closely resembling inflammatory bowel disease (IBD). Alterations to the immune environment, morphological structure, and innervation of Winnie mouse colon have been identified; however, analyses of intestinal transit and colonic functions have not been conducted. In this study, we investigated in vivo intestinal transit in radiographic studies and in vitro motility of the isolated colon in organ bath experiments. We compared neuromuscular transmission using conventional intracellular recording between distal colon of Winnie and C57BL/6 mice and smooth muscle contractions using force displacement transducers. Chronic inflammation in Winnie mice was confirmed by detection of lipocalin-2 in fecal samples over 4 wk and gross morphological damage to the colon. Colonic transit was faster in Winnie mice. Motility was altered including decreased frequency and increased speed of colonic migrating motor complexes and increased occurrence of short and fragmented contractions. The mechanisms underlying colon dysfunctions in Winnie mice included inhibition of excitatory and fast inhibitory junction potentials, diminished smooth muscle responses to cholinergic and nitrergic stimulation, and increased number of α-smooth muscle actin-immunoreactive cells. We conclude that diminished excitatory responses occur both prejunctionally and postjunctionally and reduced inhibitory purinergic responses are potentially a prejunctional event, while diminished nitrergic inhibitory responses are probably due to a postjunction mechanism in the Winnie mouse colon. Many of these changes are similar to disturbed motor functions in IBD patients indicating that the Winnie mouse is a model highly representative of human IBD.

NEW & NOTEWORTHY

This is the first study to provide analyses of intestinal transit and whole colon motility in an animal model of spontaneous chronic colitis. We found that cholinergic and purinergic neuromuscular transmission, as well as the smooth muscle cell responses to cholinergic and nitrergic stimulation, is altered in the chronically inflamed Winnie mouse colon. The changes to intestinal transit and colonic function we identified in the Winnie mouse are similar to those seen in inflammatory bowel disease patients.

Colonic response to laxative ingestion as assessed by MRI differs in constipated irritable bowel syndrome compared to functional constipation

BACKGROUND

Functional constipation (FC) and irritable bowel syndrome with constipation (IBS-C) share many symptoms but underlying mechanisms may be different. We have developed a magnetic resonance imaging (MRI) technique to measure intestinal volumes, transit, and motility in response to a laxative, Moviprep(®) . We aim to use these biomarkers to study the pathophysiology in IBS-C and FC.

METHODS

Twenty-four FC and 24 IBS-C were studied. Transit was assessed using the weighted average position score (WAPS) of five MRI marker pills, taken 24 h before MRI scanning. Following baseline scan, participants ingested 1 L of Moviprep(®) followed by hourly scans. Magnetic resonance imaging parameters and bowel symptoms were scored from 0 to 4 h.

KEY RESULTS

Weighted average position score for FC was 3.6 (2.5-4.2), significantly greater than IBS-C at 2.0 (1.5-3.2), p = 0.01, indicating slower transit for FC. Functional constipation showed greater fasting small bowel water content, 83 (63-142) mL vs 39 (15-70) mL in IBS-C, p < 0.01 and greater ascending colon volume (AC), 314 (101) mL vs 226 (71) mL in IBS-C, p < 0.01. FC motility index was lower at 0.055 (0.044) compared to IBS-C, 0.107 (0.070), p < 0.01. Time to first bowel movement following ingestion of Moviprep(®) was greater for FC, being 295 (116-526) min, compared to IBS-C at 84 (49-111) min, p < 0.01, and correlated with AC volume 2 h after Moviprep(®) , r = 0.44, p < 0.01. Using a cut-off >230 min distinguishes FC from IBS-C with low sensitivity of 55% but high specificity of 95%.

CONCLUSION & INFERENCES

Our objective MRI biomarkers allow a distinction between FC and IBS-C.

Evaluating the safety and the effects on colonic compliance of neostigmine during motility testing in patients with chronic constipation

BACKGROUND

Neostigmine, an acetyl cholinesterase inhibitor, stimulates colonic motor activity and may induce vagally mediated cardiovascular effects. Our aim was to evaluate effects of i.v. neostigmine on colonic compliance and its safety in patients with chronic constipation.

METHODS

We retrospectively reviewed medical records of a selected group of 144 outpatients with chronic constipation who were refractory to treatment. These patients had undergone intracolonic motility and compliance measurements with an infinitely compliant balloon linked to a barostat. Data abstracted included barostat balloon mean volumes with increases in pressure (4 mmHg steps from 0 to 44 mmHg) before and after i.v. neostigmine. Vital signs and oxygen saturation before and after neostigmine were recorded.

KEY RESULTS

Of the 144 patients, 133 were female, mean age was 41.0 ± 15.4 years (SD), and duration of constipation was 12.9 ± 13.8 years. Among patients who had undergone colonic transit measurement by scintigraphy, the overall colonic transit at 24 h (geometric center, GC24 [n = 115]) was 1.5 ± 0.7 (normal >1.3), and at 48 h (GC48 [n = 75]) it was 2.3 ± 0.9 (normal >1.9). Neostigmine decreased colonic compliance at lower distension pressures (e.g., 12 and 20 mmHg [both p < 0.001]), but not at 40 mmHg. There were expected minor changes in vital signs in response to neostigmine in 144 patients; however, one patient developed unresponsiveness, significant bradycardia, hypotension, and muscular rigidity that responded to 400 mcg i.v. atropine.

CONCLUSIONS & INFERENCES

Neostigmine significantly decreases colonic compliance in patients with refractory chronic constipation. Symptomatic bradycardia in response to neostigmine should be promptly reversed with atropine.

Effects of Rifaximin on Transit, Permeability, Fecal Microbiome, and Organic Acid Excretion in Irritable Bowel Syndrome

Objectives:

Rifaximin relieves irritable bowel syndrome (IBS) symptoms, bloating, abdominal pain, and loose or watery stools. Our objective was to investigate digestive functions in rifaximin-treated IBS patients.

Methods:

In a randomized, double-blind, placebo-controlled, parallel-group study, we compared the effects of rifaximin, 550 mg t.i.d., and placebo for 14 days in nonconstipated IBS and no evidence of small intestinal bacterial overgrowth (SIBO). All subjects completed baseline and on-treatment evaluation of colonic transit by scintigraphy, mucosal permeability by lactulose–mannitol excretion, and fecal microbiome, bile acids, and short chain fatty acids measured on random stool sample. Overall comparison of primary response measures between treatment groups was assessed using intention-to-treat analysis of covariance (ANCOVA, with baseline value as covariate).

Results:

There were no significant effects of treatment on bowel symptoms, small bowel or colonic permeability, or colonic transit at 24 h. Rifaximin was associated with acceleration of ascending colon emptying (14.9±2.6 h placebo; 6.9±0.9 h rifaximin; P=0.033) and overall colonic transit at 48 h (geometric center 4.0±0.3 h placebo; 4.7±0.2 h rifaximin; P=0.046); however, rifaximin did not significantly alter total fecal bile acids per g of stool or proportion of individual bile acids or acetate, propionate, or butyrate in stool. Microbiome studies showed strong associations within subjects, modest associations with time across subjects, and a small but significant association of microbial richness with treatment arm (rifaximin vs. treatment).

Conclusions:

In nonconstipated IBS without documented SIBO, rifaximin treatment is associated with acceleration of colonic transit and changes in microbial richness; the mechanism for reported symptomatic benefit requires further investigation.

Measurement of Gastrointestinal and Colonic Motor Functions in Humans and Animals

Accurately measuring the complex motor behaviors of the gastrointestinal tract has tremendous value for the understanding, diagnosis and treatment of digestive diseases. This review synthesizes the literature regarding current tests that are used in both humans and animals. There remains further opportunity to enhance such tests, especially when such tests are able to provide value in both the preclinical and the clinical settings.

Functional Anorectal Disorders

This report defines criteria and reviews the epidemiology, pathophysiology, and management of common anorectal disorders: fecal incontinence (FI), functional anorectal pain and functional defecation disorders. FI is defined as the recurrent uncontrolled passage of fecal material for at least 3 months. The clinical features of FI are useful for guiding diagnostic testing and therapy. Anorectal manometry and imaging are useful for evaluating anal and pelvic floor structure and function. Education, antidiarrheals and biofeedback therapy are the mainstay of management; surgery may be useful in refractory cases. Functional anorectal pain syndromes are defined by clinical features and categorized into three subtypes. In proctalgia fugax, the pain is typically fleeting and lasts for seconds to minutes. In levator ani syndrome (LAS) and unspecified anorectal pain the pain lasts more than 30 minutes, but in LAS there is puborectalis tenderness. Functional defecation disorders are defined by >2 symptoms of chronic constipation or irritable bowel syndrome with constipation, and with >2 features of impaired evacuation i.e., abnormal evacuation pattern on manometry, abnormal balloon expulsion test or impaired rectal evacuation by imaging. It includes two subtypes; dyssynergic defecation and inadequate defecatory propulsion. Pelvic floor biofeedback therapy is effective for treating LAS and defecatory disorders.

Functional Anorectal Disorders

This report defines criteria and reviews the epidemiology, pathophysiology, and management of common anorectal disorders: fecal incontinence (FI), functional anorectal pain and functional defecation disorders. FI is defined as the recurrent uncontrolled passage of fecal material for at least 3 months. The clinical features of FI are useful for guiding diagnostic testing and therapy. Anorectal manometry and imaging are useful for evaluating anal and pelvic floor structure and function. Education, antidiarrheals and biofeedback therapy are the mainstay of management; surgery may be useful in refractory cases. Functional anorectal pain syndromes are defined by clinical features and categorized into three subtypes. In proctalgia fugax, the pain is typically fleeting and lasts for seconds to minutes. In levator ani syndrome (LAS) and unspecified anorectal pain the pain lasts more than 30 minutes, but in LAS there is puborectalis tenderness. Functional defecation disorders are defined by >2 symptoms of chronic constipation or irritable bowel syndrome with constipation, and with >2 features of impaired evacuation i.e., abnormal evacuation pattern on manometry, abnormal balloon expulsion test or impaired rectal evacuation by imaging. It includes two subtypes; dyssynergic defecation and inadequate defecatory propulsion. Pelvic floor biofeedback therapy is effective for treating LAS and defecatory disorders.

Colon wall motility: comparison of novel quantitative semi-automatic measurements using cine MRI

BACKGROUND

Recently, cine magnetic resonance imaging (MRI) has shown promise for visualizing movement of the colonic wall, although assessment of data has been subjective and observer dependent. This study aimed to develop an objective and semi-automatic imaging metric of ascending colonic wall movement, using image registration techniques.

METHODS

Cine balanced turbo field echo MRI images of ascending colonic motility were acquired over 2 min from 23 healthy volunteers (HVs) at baseline and following two different macrogol stimulus drinks (11 HVs drank 1 L and 12 HVs drank 2 L). Motility metrics derived from large scale geometric and small scale pixel movement parameters following image registration were developed using the post ingestion data and compared to observer grading of wall motion. Inter and intra-observer variability in the highest correlating metric was assessed using Bland-Altman analysis calculated from two separate observations on a subset of data.

KEY RESULTS

All the metrics tested showed significant correlation with the observer rating scores. Line analysis (LA) produced the highest correlation coefficient of 0.74 (95% CI: 0.55-0.86), p < 0.001 (Spearman Rho). Bland-Altman analysis of the inter- and intra-observer variability for the LA metric, showed almost zero bias and small limits of agreement between observations (-0.039 to 0.052 intra-observer and -0.051 to 0.054 inter-observer, range of measurement 0-0.353).

CONCLUSIONS & INFERENCES

The LA index of colonic motility derived from cine MRI registered data provides a quick, accurate and non-invasive method to detect wall motion within the ascending colon following a colonic stimulus in the form of a macrogol drink.

Relationship Between Microbiota of the Colonic Mucosa vs Feces and Symptoms, Colonic Transit, and Methane Production in Female Patients With Chronic Constipation

BACKGROUND & AIMS

In fecal samples from patients with chronic constipation, the microbiota differs from that of healthy subjects. However, the profiles of fecal microbiota only partially replicate those of the mucosal microbiota. It is not clear whether these differences are caused by variations in diet or colonic transit, or are associated with methane production (measured by breath tests). We compared the colonic mucosal and fecal microbiota in patients with chronic constipation and in healthy subjects to investigate the relationships between microbiota and other parameters.

METHODS

Sigmoid colonic mucosal and fecal microbiota samples were collected from 25 healthy women (controls) and 25 women with chronic constipation and evaluated by 16S ribosomal RNA gene sequencing (average, 49,186 reads/sample). We assessed associations between microbiota (overall composition and operational taxonomic units) and demographic variables, diet, constipation status, colonic transit, and methane production (measured in breath samples after oral lactulose intake).

RESULTS

Fourteen patients with chronic constipation had slow colonic transit. The profile of the colonic mucosal microbiota differed between constipated patients and controls (P < .05). The overall composition of the colonic mucosal microbiota was associated with constipation, independent of colonic transit (P < .05), and discriminated between patients with constipation and controls with 94% accuracy. Genera from Bacteroidetes were more abundant in the colonic mucosal microbiota of patients with constipation. The profile of the fecal microbiota was associated with colonic transit before adjusting for constipation, age, body mass index, and diet; genera from Firmicutes (Faecalibacterium, Lactococcus, and Roseburia) correlated with faster colonic transit. Methane production was associated with the composition of the fecal microbiota, but not with constipation or colonic transit.

CONCLUSIONS

After adjusting for diet and colonic transit, the profile of the microbiota in the colonic mucosa could discriminate patients with constipation from healthy individuals. The profile of the fecal microbiota was associated with colonic transit and methane production (measured in breath), but not constipation.

Relamorelin Relieves Constipation and Accelerates Colonic Transit in a Phase 2, Placebo-Controlled, Randomized Trial

BACKGROUND & AIMS

Ghrelin receptors are located in the colon. Relamorelin is a pentapeptide selective agonist of ghrelin receptor 1a with gastric effects, but its effects in the colon are not known. We aimed to evaluate the effects of relamorelin on bowel movements (BMs) and gastrointestinal and colonic transit (CT) in patients with chronic constipation.

METHODS

We performed a study of 48 female patients with chronic constipation who fulfilled the Rome III criteria and had 4 or fewer spontaneous BMs (SBMs)/wk. In a randomized (1:1), double-blind, parallel-group, placebo-controlled trial, the effects of relamorelin (100 μg/d, given subcutaneously) were tested during 14 days after a 14-day baseline, single-blind phase in which patients were given placebo at 2 Mayo Clinic sites. The participants' mean age was 40.6 ± 1.5 y, with a mean body mass index of 25.7 ± 0.6 kg/m(2), with 1.7 ± 0.1 SBM/wk, and a mean stool consistency of 1.2 ± 0.1 on the Bristol scale during this baseline period. The effect of treatment on transit was measured in 24 participants with colonic transit of less than 2.4 (geometric center at 24 h) during the baseline period. Gastric emptying, small-bowel transit, and CT were measured during the last 2 days that patients received relamorelin or placebo. Bowel function was determined from daily diaries kept by patients from days 1 through 28. Study end points were time to first BM, SBMs/wk, complete SBMs/wk, stool form, and ease of stool passage. Effects of relamorelin were assessed by analysis of covariance.

RESULTS

Compared with placebo, relamorelin accelerated gastric emptying half-time (P = .027), small-bowel transit (P = .051), and CT at 32 hours (P = .040) and 48 hours (P = .017). Relamorelin increased the number of SBMs (P < .001) and accelerated the time to first BM after the first dose was given (P = .004) compared with placebo, but did not affect stool form. Adverse events associated with relamorelin included increased appetite, fatigue, and headache.

CONCLUSIONS

Relamorelin acts in the colon to significantly reduce symptoms of constipation and accelerate CT in patients with chronic constipation, compared with placebo. ClinicalTrial.Gov registration number: NCT01781104.

Effect of neostigmine on gastroduodenal motility in patients with suspected gastrointestinal motility disorders

BACKGROUND

Acetylcholinesterase inhibitors (ACIs), e.g., neostigmine, are known to increase upper and lower gastrointestinal (GI) motility and are used to treat acute colonic pseudoobstruction. However, their effects on gastroduodenal motility in humans are poorly understood. Our hypotheses were that, in patients with suspected GI motility disorders, neostigmine increases gastric and small intestinal motor activity, and these effects are greater in patients with cardiovagal neuropathy, reflecting denervation sensitivity.

METHODS

In this open label study, the effects of neostigmine (1 mg intravenously) on gastroduodenal motor activity recorded with manometry were assessed in 28 patients with a suspected GI motility disorder. Cardiovagal function was assessed with the heart rate response to deep breathing and GI transit by scintigraphy.

KEY RESULTS

The final diagnoses were gastroparesis (6 patients), gastroparesis with intestinal neuropathy (3 patients), intestinal neuropathy or pseudoobstruction (5 patients), functional dyspepsia (6 patients), chronic abdominal pain (3 patients), mechanical small intestinal obstruction (3 patients), and pelvic floor dysfunction (2 patients). Neostigmine increased both antral and intestinal phasic pressure activity (p < 0.001). Neostigmine increased antral and intestinal pressure activity in 81% and 50% of patients with reduced postprandial antral and intestinal contractile responses to meal, respectively. The antroduodenal pressure response to neostigmine was not higher in patients with cardiovagal dysfunction.

CONCLUSIONS & INFERENCES

Neostigmine increased antral and intestinal motor activity in patients with hypomotility, including intestinal dysmotility. These responses to neostigmine were not greater in patients with cardiovagal dysfunction. The use of longer-acting ACIs for treating antroduodenal dysmotility warrant further study.

Review article: biomarkers and personalised therapy in functional lower gastrointestinal disorders

BACKGROUND

Treatment of IBS and functional lower gastrointestinal disorders is still based predominantly on symptoms; biomarkers that reflect the mechanism or pathophysiology have been identified. Given the diverse mechanisms that result in the same clinical phenotype of IBS, it is hypothesised that identification of biomarkers may lead to individualisation of medical therapy.

AIM

To review the biomarkers that have been appraised in IBS.

METHODS

A single author reviewed the published literature on biomarkers appraised in IBS.

RESULTS

The current literature suggests that these biomarkers are insufficiently sensitive or specific to differentiate IBS from health or from other diseases causing similar symptoms, such as coeliac disease or inflammatory bowel disease. Most of the proposed biomarkers are not actionable, that is, they do not lead to an efficacious therapy based on the biological inference of the biomarker itself. However, among proposed biomarkers in IBS, some are actionable, as they specifically reflect a quantitative difference in a mediator of dysfunction or result in a quantifiable disturbance of function that can be specifically treated. Such biomarkers may potentially identify relevant subgroups that respond to specific therapy. The most promising actionable biomarkers are measurement of colonic transit (leading to treatments that reverse the abnormal transit) and measurements of bile acid diarrhoea to identify responders to bile acid sequestrants.

CONCLUSIONS

Therefore, although biomarkers are not ready for prime time as diagnostic tests in IBS, some biomarkers could identify subgroups of patients with IBS for inclusion in clinical trials that target specific dysfunctions. Such an approach may enhance treatment efficacy, and may ultimately help reduce costs in drug development and in the management of patients in clinical practice.

How many segments are necessary to characterize delayed colonic transit time?

BACKGROUND AND AIMS

Measuring colonic transit time with radiopaque markers is simple, inexpensive, and very useful in constipated patients. Yet, the algorithm used to identify colonic segments is subjective, rather than founded on prior experimentation. The aim of the present study is to describe a rational way to determine the colonic partition in the measurement of colonic transit time.

METHODS

Colonic transit time was measured in seven segments: ascending colon, hepatic flexure, right and left transverse colon, splenic flexure, descending colon, and rectosigmoid in 852 patients with functional bowel and anorectal disorders. An unsupervised algorithm for modeling Gaussian mixtures served to estimate the number of subgroups from this oversegmented colonic transit time. After that, we performed a k-means clustering that separated the observations into homogenous groups of patients according to their oversegmented colonic transit time.

RESULTS

The Gaussian mixture followed by the k-means clustering defined 4 populations of patients: "normal and fast transit" (n = 548) and three groups of patients with delayed colonic transit time "right delay" (n = 82) in which transit is delayed in the right part of the colon, "left delay" (n = 87) with transit delayed in the left part of colon and "outlet constipation" (n = 135) for patients with transit delayed in the terminal intestine. Only 3.7 % of patients were "erroneously" classified in the 4 groups recognized by clustering.

CONCLUSIONS

This unsupervised analysis of segmental colonic transit time shows that the classical division of the colon and the rectum into three segments is sufficient to characterize delayed segmental colonic transit time.

Irritable bowel syndrome: modern concepts and management options

Irritable bowel syndrome is the most common functional gastrointestinal disorder, manifesting as abdominal pain/discomfort and altered bowel function. Despite affecting as many as 20% of adults, a lack of understanding of etiopathogenesis and evaluation strategies results in diagnostic uncertainty, and in turn frustration of both the physician and the patient. This review summarizes the current literature on the diagnosis and management of irritable bowel syndrome, with attention to evidence-based approaches. A 4-step treatment strategy that has been used successfully in our tertiary referral practice is presented and should lead to successful therapeutic outcomes in the majority of patients with irritable bowel syndrome.

Colonic mucosal gene expression and genotype in irritable bowel syndrome patients with normal or elevated fecal bile acid excretion

The mucosal gene expression in rectosigmoid mucosa (RSM) in irritable bowel syndrome with diarrhea (IBS-D) is unknown. Our objectives were, first, to study mRNA expression [by RT(2) PCR of 19 genes pertaining to tight junctions, immune activation, intestinal ion transport and bile acid (BA) homeostasis] in RSM in IBS-D patients (n = 47) and healthy controls (n = 17) and study expression of a selected protein (PDZD3) in 10 IBS-D patients and 4 healthy controls; second, to assess RSM mRNA expression according to genotype and fecal BA excretion (high ≥ 2,337 μmol/48 h); and third, to determine whether genotype or mucosal mRNA expression is associated with colonic transit or BA parameters. Fold changes were corrected for false detection rate for 19 genes studied (P < 0.00263). In RSM in IBS-D patients compared with controls, mRNA expression of GUC2AB, PDZD3, and PR2Y4 was increased, whereas CLDN1 and FN1 were decreased. One immune-related gene was upregulated (C4BP4) and one downregulated (CCL20). There was increased expression of a selected ion transport protein (PDZD3) on immunohistochemistry and Western blot in IBS-D compared with controls (P = 0.02). There were no significant differences in mucosal mRNA in 20 IBS-D patients with high compared with 27 IBS-D patients with normal BA excretion. GPBAR1 (P < 0.05) was associated with colonic transit. We concluded that mucosal ion transport mRNA (for several genes and PDZD3 protein) is upregulated and barrier protein mRNA downregulated in IBS-D compared with healthy controls, independent of genotype. There are no differences in gene expression in IBS-D with high compared with normal fecal BA excretion.

A randomized trial of 5-hydroxytryptamine4-receptor agonist, YKP10811, on colonic transit and bowel function in functional constipation

BACKGROUND & AIMS

YKP10811, a selective agonist of the serotonin 5-hydroxytryptamine-4 receptor, increases gastrointestinal (GI) motility. We investigated the safety and effects of YKP10811 on GI and colonic transit and bowel movements (BMs) in patients with functional constipation in a randomized, double-blind, placebo-controlled study.

METHODS

Patients with functional constipation, based on the Rome III criteria, were assigned randomly to groups given YKP10811 10 mg (n = 15), 20 mg (n = 16), 30 mg (n = 15), or placebo (n = 11) daily for 8 days. Transit of solids was measured by validated scintigraphy at baseline and on days 7 to 9. Patients kept diaries on days 1 to 9, recording time to first BM, number of BMs/day, and stool consistency (based on the Bristol Stool Form Scale). To evaluate safety, we collected data on adverse events and clinical laboratory test and electrocardiograms results. The primary efficacy end points were determined from an intent-to-treat analysis assessing colonic transit at 24 hours and the half-time (t1/2) of gastric emptying, using analysis of covariance models. Secondary efficacy end points included measures of colonic transit (geometric center at 4 and 24 hours), small-bowel transit (based on colon filling at 6 hours), t1/2 of ascending colon emptying, and bowel functions. We used the Dunnett test to compare the effects of each dose with placebo. A per-protocol analysis (PPA) assessed the t1/2 of gastric emptying and time to first BM using proportional hazards models.

RESULTS

Fifty-five participants completed the study. YKP10811 was associated with a significant acceleration in colon filling at 6 hours (P < .05), t1/2 of ascending colon emptying, and colonic transit at 24 and 48 hours, as well as increased stool consistency over 8 days (based on intent-to-treat analysis). In general, the 10-mg and 20-mg doses were the most effective in accelerating colonic transit. No serious adverse events were observed.

CONCLUSIONS

YKP10811, a selective agonist of the serotonin receptor 5-hydroxytryptamine-4, accelerates GI and colonic transit and improves bowel functions in patients with functional constipation, compared with placebo. ClinicalTrial.Gov: NCT01523184.

Disturbances of gastrointestinal transit and autonomic functions in postural orthostatic tachycardia syndrome

BACKGROUND

Gastrointestinal symptoms are common in the postural orthostatic tachycardia syndrome (POTS). However, few studies have evaluated gastrointestinal transit in POTS. Our primary objectives were to evaluate gastrointestinal emptying and the relationship with autonomic dysfunctions in POTS.

METHODS

We reviewed the complete medical records of all patients aged 18 years and older with POTS diagnosed by a standardized autonomic reflex screen who also had a scintigraphic assessment of gastrointestinal transit at Mayo Clinic Rochester between 1998 and 2012. Associations between specific gastric emptying and autonomic (i.e., cardiovagal, adrenergic, and sudomotor) disturbances were evaluated.

KEY RESULTS

Among 163 patients (140 women, mean [± SEM] age 30 [± 1] years), 55 (34%) had normal, 30 (18%) had delayed, and 78 (48%) had rapid gastric emptying. Fifty-eight patients (36%) had clinical features of physical deconditioning, which was associated (p = 0.02) with rapid gastric emptying. Associations with delayed gastric emptying included vomiting, which was more common (p < 0.003), and anxiety or depression, which was less common (p = 0.02). The tilt-associated increase in heart rate and reduction in systolic BP at 1 min was associated (p < 0.05), being greater in patients with delayed gastric emptying.

CONCLUSIONS & INFERENCES

Two-thirds of patients with POTS and GI symptoms had abnormal, most frequently rapid gastric emptying. Except for more severe adrenergic impairment in patients with delayed gastric emptying, the pattern of autonomic dysfunction did not discriminate among gastric emptying groups. Further studies are necessary to ascertain whether extravascular volume depletion and/or deconditioning contribute to POTS in patients with gastrointestinal symptoms.