Gender differences in chronic constipation on anorectal motility

Prevalence and associated factors of chronic constipation among Japanese university students

Background

Chronic constipation (CC) is one of the most frequently reported gastrointestinal disorders in the general population and a prominent problem among university students. The study aimed to evaluate the prevalence and the associated factors of CC among Japanese university students.

Methods

This cross-sectional study was conducted among university students at Hiroshima University, Japan. Students answered the web questionnaire when making a web reservation for the health checkup (April 1 to May 31, 2023). The web questionnaire consisted of four sections, including baseline characteristics, lifestyle factors, family history of CC, and three scales to assess depression and eating disorders: the Beck Depression Inventory (BDI), Eating Attitudes Test (EAT)-26 and Bulimic Investigatory Test (BITE). CC was diagnosed using Rome IV criteria. The multivariate logistic regression model was used to determine CC-related factors.

Results

Out of 10,500 individuals who participated in the annual health checkup, 7,496 participants answered the web questionnaire, of whom 5,386 answered all the survey questions. The mean age of the students was 21.1 ± 4.1 years. The male-to-female ratio was 1:1.17. The prevalence of CC was 13.7%. Factors significantly associated with CC in the multivariate model were first-degree family members with CC [Odd ratio (OR): 2.77, 95% confidence interval (CI): 2.31-3.31], severe depression according to BDI scale (OR: 2.59, 95% CI: 1.96-3.43), female sex (OR: 2.00, 95% CI: 1.69-2.36), and short sleep duration of 6 hours or less per day (OR: 1.28, 95% CI: 1.09-1.50). Lack of physical exercise tended to be associated with CC (OR: 1.19, 95% CI: 1.00-1.40).

Conclusions

CC is prevalent among Japanese university students. Significant risk factors for CC included the first-degree family history of CC, severe depression, female sex, and short sleep duration. Lack of physical exercise tended to be associated with CC. This may contribute to implementing suitable education health programs, health care professionals, and public health policies to identify individuals at risk for CC to prevent and treat CC effectively.

Differences in Cholesterol Metabolism, Hepato-Intestinal Aging, and Hepatic Endocrine Milieu in Rats as Affected by the Sex and Age

Age and sex influence serum cholesterol levels, but the underlying mechanisms remain unclear. To investigate further, we measured cholesterol, precursors (surrogate synthesis markers), degradation products (oxysterols and bile acid precursors) in serum, the liver, jejunum, and ileum, as well as serum plant sterols (intestinal absorption markers) in male and female Wistar rats (4 and 24 months old). The analysis of histomorphometric and oxidative stress parameters (superoxide dismutase, catalase, glutathione-related enzyme activities, lipid peroxide, and protein carbonyl concentrations) in the liver and jejunum offered further insights into the age- and sex-related differences. The hepatic gene expression analysis included AR, ERα, and sex-specific growth hormone-regulated (Cyp2c11 and Cyp2c12) and thyroid-responsive (Dio1, Tbg, and Spot 14) genes by qPCR. We observed age-related changes in both sexes, with greater prominence in females. Aged females had significantly higher serum cholesterol (p < 0.05), jejunum cholesterol (p < 0.05), and serum plant sterols (p < 0.05). They exhibited poorer hepato-intestinal health compared with males, which was characterized by mild liver dysfunction (hydropic degeneration, increased serum ALT, p < 0.05, and decreased activity of some antioxidant defense enzymes, p < 0.05), mononuclear inflammation in the jejunal lamina propria, and age-related decreases in jejunal catalase and glutathione peroxidase activity (p < 0.05). Aged females showed increased levels of 27-hydroxycholesterol (p < 0.05) and upregulated ERα gene expression (p < 0.05) in the liver. Our study suggests that the more significant age-related increase in serum cholesterol in females is associated with poorer hepato-intestinal health and increased jejunal cholesterol absorption. The local increase in 27-hydroxycholesterol during aging might reduce the hepatoprotective effects of endogenous estrogen in the female liver.

Recto-anal Pressures in Constipated Men and Women Undergoing High-Resolution Anorectal Manometry

BACKGROUND

In constipated individuals, high-resolution anorectal manometry (HRM) may suggest the presence of a defecatory disorder. Despite known physiological differences between men and women, our understanding of functional anorectal pathophysiology is based upon predominantly female cohorts. Results are generalized to men.

AIMS

To evaluate whether recto-anal pressure patterns in constipated men are similar to those in constipated women.

METHODS

The electronic health records at Mayo Clinic, Rochester were used to identify constipated adult patients, without organic anorectal disease, who had undergone HRM and balloon expulsion testing (BET) in 2018, 2019, and 2020. Comparative analyses were performed.

RESULTS

Among 3,298 constipated adult patients (2,633 women, 665 men), anal and rectal pressures were higher in men. Women more likely to have HRM findings suggestive of a defecatory disorder (39% versus 20%, P < 0.001). Women were more likely to exhibit a type 4 pattern (27% versus 14%, P < 0.001), and less likely to exhibit a type 1 pattern (14% versus 38%, P < 0.001), of dyssynergia. Men were more likely to have an abnormal balloon expulsion test (BET, 34% versus 29%, P = 0.006). Nominal logistic regression demonstrates that male sex, age over 50 years, reduced recto-anal gradient during simulated evacuation, and types 2 and 4 dyssynergia are associated with an abnormal BET.

CONCLUSIONS

In this large retrospective study, constipated men and women exhibited different patterns of dyssynergia both in the presence and absence of an abnormal BET. These findings were independent of sex-specific baseline physiological differences.

Age- and Gender-Based Differences in Anorectal Function, Gastrointestinal Symptoms, and Constipation-Specific Quality of Life in Patients with Chronic Constipation

BACKGROUND

The effect of age and gender differences on anorectal function, symptoms severity, and quality of life (QoL) in patients with chronic constipation (CC) is not well studied. This study examines the impact of age and gender on anorectal function testing (AFT) characteristics, symptoms burden, and QoL in patients with CC.

METHODS

This is a retrospective analysis of prospectively collected data from 2550 adults with CC who completed AFT. Collected data include demographics, sphincter response to simulated defecation during anorectal manometry (ARM), balloon expulsion testing (BET), and validated surveys assessing constipation symptoms and QoL. DD was defined as both the inability to relax the anal sphincter during simulated defecation and an abnormal BET.

RESULTS

2550 subjects were included in the analysis (mean age = 48.6 years). Most patients were female (81.6%) and Caucasian (82%). 73% were < 60 years old (mean = 41) vs. 27% ≥ 60 years old (mean = 69). The prevalence of impaired anal sphincter relaxation on ARM, abnormal BET, and DD in patients with CC was 48%, 42.1%, and 22.9%, respectively. Patients who were older and male were significantly more frequently diagnosed with DD and more frequently had impaired anal sphincter relaxation on ARM, compared to patients who were younger and female (p < 0.05). Conversely, CC patients who were younger and female reported greater constipation symptoms severity and more impaired QoL (p ≤ 0.004).

CONCLUSION

Among patients with CC referred for anorectal function testing, men and those older than 60 are more likely to have dyssynergic defecation, but women and patients younger than 60 experience worse constipation symptoms and QoL.

Clinical value of positive BET and pelvic floor dyssynergia in Chinese patients with functional defecation disorder

BACKGROUND

Functional defecation disorder (FDD) is a common subtype of functional constipation (FC). Balloon expulsion test (BET) and high resolution anorectal manometry (HR-ARM) are significant tools but their results are not always consistent.

AIMS

To investigate the characteristics of patients with positive BET and pelvic floor dyssynergia (PFD) and explore the value of both positive results in FDD diagnosis.

METHODS

We retrospectively diagnosed FC subtypes and enrolled FDD patients based on Rome-IV criteria. They underwent HR-ARM, BET and CTT tests. Then they were classified to two groups and further stratified by FDD subtypes. Validated questionnaires were applied to investigate patients' constipation, anxiety/depression and quality of life.

RESULTS

335 FDD patients were finally enrolled. They were classified into two groups according to whether BET and PFD were both positive (consistent or not). 84.48% showed consistent results. These patients had significantly higher anal residual pressure, lower anal relaxation rate, manometric defecation index (MDI) and a more negative rectoanal pressure gradient (RAPG) (Ps < .05). The specific distribution of FDD phenotypes in two groups showed significant difference (p = .021). Males suffered a more negative RAPG (p < .001) and age was correlated with anal relaxation rate (p < .001). A subset (177 individuals) was investigated with validated questionnaires. Scores for Defecation Symptoms, Physical Discomfort and GAD-7 score were significantly high in Consistent Group (Ps < .05). GAD-7 score was associated with Defecation Symptoms (p < .001) while anal residual pressure, GAD-7 and Defecation Symptoms score were linked to Physical Discomfort (Ps < .05). The diagnostic specificity and PPV for FDD rose significantly with positive BET and PFD.

CONCLUSION

FDD patients with positive BET and PFD suffered from severe defecation symptoms, anxiety and impaired QOL. Positive BET and PFD could be an ideal tool for screening FDD.

Epidemiology of Constipation in Elderly People in Parts of China: A Multicenter Study

Purpose

To investigate the epidemiological characteristics of constipation in people aged 65 years and older in several regions of China.

Patients and Methods

A cross-sectional study based on a cluster sampling design was conducted in four cities of China: Tianjin, Xiamen, Cangzhou and Harbin. A total of 5,222 cases (age ≥ 65 years) were recruited, and the survey was conducted via centralized and household questionnaires that included the following: basic demographic characteristics such as sex, age, education, marital status, living status and occupation; social activities; duration of sleep at night; duration of menstruation and delivery times (in females); and if the participant had constipation symptoms, the severity of constipation. Constipation was diagnosed according to the Rome IV criteria.

Results

Of the 5,222 participants, 919 were diagnosed with constipation. The prevalence of constipation was 17.60% in elderly people ≥65 years old. Prevalence increased with age and was significantly higher in females than males (P < 0.05). Prevalence was lower in the manual compared to the non-manual worker group, and significantly increased with decreasing duration of night sleep (P < 0.05). Older age, female sex and shorter sleep duration at night were risk factors for constipation in elderly people.

Conclusion

The prevalence of constipation in the elderly people in four cities of China was 17.60%, and was significantly affected by age, sex and sleep duration at night.

Efficacy and Safety of Maxing Xianchang Su in the Treatment of Functional Constipation: A Randomized Controlled Trial

Background

Functional constipation (FC) is one of the prevalent gastrointestinal disorders that affect people of all ages. Long-term FC has significant effects on the quality of life of patients. Although commonly used drugs have reliable short-term effects, they are easily addictive and have side effects. Therefore, pursuing a convenient drug-food homogenous program is critical for FC patients. Maxing Xianchang Su is a functional food based on traditional Chinese medicine. To investigate the efficacy and safety of Maxing Xianchang Su in FC treatment, we conducted a randomized controlled trial.

Methods

We carried out a prospective multicenter randomized parallel controlled study in three hospitals in Jiangsu Province, China, from January 2020 to March 2021, which included 206 FC patients. All patients were arbitrarily assigned into a treatment group and a control group at a ratio of 1 : 1; 103 cases in each group. The treatment group was given oral Maxing Xianchang Su, whereas the control group was treated with lactulose oral solution. The course of treatment was two weeks. The two groups of patients were evaluated after six weeks for symptom improvement before and after taking the drug. Furthermore, the safety of Maxing Xianchang Su was assessed.

Results

Both groups of patients successfully completed the study without shedding cases. The effective rates of the treatment group and control group after two weeks were 90.6% and 67.0%, respectively. The treatment group had a better curative effect than the control group (P < 0.05). The symptom score of the two groups improved compared with that before the treatment. The difference between the two groups was statistically significant (P < 0.05). During the treatment process, neither group experienced abnormal changes in blood lipid, blood glucose, routine hematuria, or liver and kidney functions. There were no adverse reactions in both groups.

Conclusion

Maxing Xianchang Su has a positive effect on FC treatment with reliable mid-term effect and a high level of safety.

Rectal Distension Increased the Rectoanal Gradient in Patients with Normal Rectal Sensory Function

BACKGROUND

Frequent observation of abnormal manometric patterns consistent with dyssynergia in healthy volunteers has warranted the need for reassessment of the current methods to enhance the diagnostic value of anorectal manometry in functional defecatory disorders. Whether rectal distention at simulated evacuation will affect anorectal pressure profile and increase rectoanal gradient is not known.

METHODS

One hundred and eight consecutive patients with chronic constipation, 93 females, median age 53 years (interquartile range: 40-65), were studied. Simulated evacuation was performed firstly with empty balloon and subsequently after balloon distention to 50 and 100 ml. Anorectal pressures were compared. We also performed subgroup analysis in relation to outcome of balloon expulsion test (BET). In addition, we studied the effect of rectal distension on the rectoanal pressure gradient with respect to rectal sensory function.

RESULTS

Rectal balloon distension at simulated evacuation improved rectoanal gradient and decreased the rate of dyssynergia during high-resolution anorectal manometry. In subgroup analysis, the increase in rectoanal gradient and correction of dyssynergia with rectal distension was limited to the patients who had normal BET and normal rectal sensory function. Rate of anal relaxation, residual anal pressures, and rectoanal gradient were significantly different between patients with and without normal BET at 50 ml of rectal distension. Rectoanal gradient recorded only after rectal distension, along with BMI and maximum tolerable volumes, could predict BET results independently in patients with chronic constipation.

CONCLUSIONS

Rectal distension during simulated evacuation will affect the anorectal pressure profile. Increase in rectoanal gradient and correction of dyssynergia was only significant in patients with normal rectal sensory function and normal BET.

Prebiotic UG1601 mitigates constipation-related events in association with gut microbiota: A randomized placebo-controlled intervention study

BACKGROUND

Constipation is a common functional gastrointestinal disorder and its etiology is multifactorial. Growing evidence suggests that intestinal dysbiosis is associated with the development of constipation. Prebiotics are subjected to bacterial fermentation in the gut to produce short-chain fatty acids (SCFAs), which can help relieve constipation symptoms. The prebiotic UG1601 consists of inulin, lactitol, and aloe vera gel, which are known laxatives, but randomized, controlled clinical trials that examine the effects of this supplement on gut microbiota composition are lacking.

AIM

To assess the efficacy of the prebiotic UG1601 in suppressing constipation-related adverse events in subjects with mild constipation.

METHODS

Adults with a stool frequency of less than thrice a week were randomized to receive either prebiotics or a placebo supplement for 4 wk. All participants provided their fecal and blood samples at baseline and at the end of intervention. Gastrointestinal symptoms and stool frequency were evaluated. The concentrations of serum endotoxemia markers and fecal SCFAs were determined. The relative abundance of SCFA-producing bacteria and the gut microbial community in the responders and non-responders in the prebiotics supplementation group were evaluated.

RESULTS

There were no significant differences in gastrointestinal symptoms between groups, although the prebiotic group showed greater symptom improvement. However, after prebiotic usage, serum cluster of differentiation (CD) 14 and lipopolysaccharide (LPS) concentrations were significantly decreased (CD14, P = 0.012; LPS, P < 0.001). The change in LPS concentration was significantly larger in the prebiotic group than in the placebo group (P < 0.001). Fecal SCFAs concentrations did not differ between groups, while the relative abundance of Roseburia hominis, a major butyrate producer, was significantly increased in the prebiotic group (P = 0.045). The abundances of the phylum Firmicutes and the family Lachnospiraceae (phylum Firmicutes, class Clostridia) (P = 0.009) were decreased in the responders within the prebiotic group. In addition, the proportions of the phylum Firmicutes, the class Clostridia, and the order Clostridiales were inversely correlated with several fecal SCFAs (P < 0.05).

CONCLUSION

Alterations in gut microbiota composition, including a decrease in the phylum Firmicutes and an increase in butyrate-producing bacteria, following prebiotic UG1601 supplementation might help alleviate symptom scores and endotoxemia.

A Randomized Controlled Trial on the Effects of Electromyographic Biofeedback on Quality of Life and Bowel Symptoms in Elderly Women With Dyssynergic Defecation

Dyssynergic defecation is a usual cause of chronic constipation in elderly women, with a negative impact on health-related quality of life. The present randomized controlled trial aims to evaluate the effects of behavioral treatment through electromyographic biofeedback (EMG-BF) on quality of life and bowel symptoms in elderly women with dyssynergic defecation. Twenty chronically constipated elderly women, due to dyssynergic defecation, were enrolled in the study. Outcome measures included weekly stool frequency, anismus index, severity of patient-reported chronic constipation symptoms (abdominal, rectal, and stool symptoms), and overall measure of quality of life. After 1 month of baseline, participants were randomly assigned to either EMG-BF group (n = 10) or control group (n = 10). Three months after treatment, female patients were once again assessed following the same procedure in baseline. One-way multivariate analysis of variance MANOVA revealed no significant differences between the groups before treatment in any of the measured dependent variables (Wilks's λ = 0.74; F_6,13 = 0.77; p = 0.61). Likewise, univariate analysis showed no differences between the groups, either in terms of age (F_1,18 = 0.96; p = 0.34) or mean disease duration (F_1,18 = 2.99; p = 0.11). Three months after treatment, MANOVA revealed statistically significant differences between the groups (Wilks's λ = 0.29; F_6,13 = 5.19; p < 0.01). These differences were significant in all outcome measures. EMG-BF produces significant improvements in bowel symptoms and health-related quality of life of elderly women with dyssynergic defecation.

High-resolution Anorectal Manometry in the Diagnosis of Functional Defecation Disorder in Patients With Functional Constipation: A Retrospective Cohort Study

Background/Aims

High-resolution anorectal manometry (HRAM) has been considered a first-line diagnostic tool for functional defecation disorder. However, clinical studies on HRAM used in constipation patients are very limited and few studies have reported the characteristics of anorectal pressure in Chinese patients. The aim of this study is to investigate the characteristics of motility data in a cohort of Chinese patients with functional constipation.

Methods

A total of 82 consecutive patients with functional constipation who underwent a standardized HRAM were retrospectively enrolled in this study. The functional defecation disorder was classified into Rao’s types.

Results

The mean age of 82 patients was 51 years (range, 16–83 years). Indications for anorectal manometry were functional constipation for all patients. The mean resting pressure was 69.2 ± 21.2 mmHg (range, 24.5–126.9 mmHg). The mean maximum squeezing pressure was 198.4 ± 75.6 mmHg (range, 54.2–476.9 mmHg). The mean length of the anal high pressure zone was 3.4 ± 1.0 cm (range, 0.6–4.9 cm). Sixty (73.2%) patients were diagnosed as functional defecation disorder. In attempted defecation, type I was most common (n = 24), followed by type II (n = 12), type III (n = 11), and type IV (n = 13) that were present on HRAM according to Rao’s classification. In all 60 patients with functional defecation disorder, 37 were women and 23 were men. Men were significantly more likely than women to have functional defecation disorder (92.0% vs 64.9%, P = 0.014).

Conclusion

HRAM could be used as a test for the diagnosis of functional defecation disorder and functional defecation disorder is common in Chinese patients with functional constipation.

Functional anal canal length measurement using high-resolution anorectal manometry to investigate anal sphincter dysfunction in patients with fecal incontinence or constipation

BACKGROUND

Using high-resolution anorectal manometry, we aimed to evaluate the: (a) optimal threshold to measure functional anal canal length (FACL) with intra- and inter-observer variability; (b) relationship between abnormal FACL and other phenotypic findings; and (c) utility of FACL measurement to discriminate between healthy volunteers (HV) and patients with fecal incontinence (FI) or chronic constipation (CC).

METHODS

Consecutive patients referred for investigation of FI or CC in isolation were included. FACL was calculated at 5, 10, 20, 30, and 50 mm Hg above rectal pressure. 5th-95th percentile in HV defined limits of normality.

KEY RESULTS

FACL was analyzed in 192 patients with FI (154 females), 204 patients with CC (175 females), and 134 HV (101 females). The optimal threshold for measurement of FACL was 20 mm Hg. Using this threshold, observer reproducibility was very high (ICC 0.99, P < 0.0001). FACL was shorter in females with FI and longer in females with CC compared to HV (2.3 vs 2.9 cm; and 3.4 cm vs 2.9 cm; both P < 0.0001). Twenty percent of females and 13% males with FI had a short FACL, associated with older age, anal hypotonia or hypocontractility, and a atrophic internal anal sphincter. However, abnormal FACL in isolation was only found in 1/190 FI (0.5%) and 2/201 CC (1%) patients; all other patients had other abnormal manometric findings.

CONCLUSIONS AND INFERENCES

Considering overlap with other routinely evaluated manometric parameters, FACL measurement does not provide additional information in the diagnostic assessment of FI or CC.

Pelvic Floor Symptom Related Distress in Chronic Constipation Correlates With a Diagnosis of Irritable Bowel Syndrome With Constipation and Constipation Severity but Not Pelvic Floor Dyssynergia

Background/Aims

Although symptoms related to the pelvic floor, such as pelvic organ prolapse (POP) and lower urinary tract symptoms (LUTS), are common in patients with chronic constipation (CC), its impact is not clear. Our aims were to investigate the following (1) compare pelvic floor symptom related dysfunction in irritable bowel syndrome with constipation (IBS-C) and functional constipation (FC), and (2) symptom correlation with findings on anorectal manometry (ARM) and balloon expulsion test.

Methods

This was a retrospective analysis of patients with CC undergoing ARM. IBS-C and FC were diagnosed by Rome III criteria. Pelvic Floor Distress Inventory (PFDI-20) was used to measure pelvic floor symptom distress. Constipation Severity Scale was used to assess constipation severity.

Results

A total of 107 patients underwent ARM (64 FC, 43 IBS-C). The overall PFDI-20 score in IBS-C was higher compared with FC patients (118.0 vs 79.2, P = 0.001). In those with IBS-C, POP, LUTS, and colorectal symptoms subscales were all higher compared with FC patients ( P ＜ 0.05 for each). On multivariable regression, IBS-C ( P = 0.001) and higher constipation severity ( P = 0.001) were both independently associated with higher PFDI scores. ARM parameters and abnormal balloon expulsion test did not correlate with PFDI scores.

Conclusions

Compared with FC patients, those with IBS-C have significantly higher distress from pelvic floor specific symptoms including POP and LUTS. Higher abdominal pain among IBS-C patients did not entirely explain these findings. A diagnosis of IBS-C and higher constipation severity correlated with PFDI-20 scores, but dyssynergia did not.

Examining Balloon Expulsion Testing as an Office-Based, Screening Test for Dyssynergic Defecation: A Systematic Review and Meta-Analysis

OBJECTIVES

Balloon expulsion testing (BET) is recommended to evaluate for dyssynergic defecation in patients with chronic constipation (CC). However, it remains poorly standardized and is limited to specialized centers. Our goal was to assess the clinical utility of balloon expulsion as an initial test for dyssynergic defecation and to determine appropriate testing parameters.

METHODS

We performed a literature search to identify cohort studies of unselected subjects with CC and case-control studies of subjects with/without dyssynergic defecation. We defined dyssynergic defecation by constipation symptoms and a positive reference test (anorectal manometry [ARM], defecography, or electromyography [EMG]). We performed a meta-analysis using a bivariate mixed-effects regression model to assess summary sensitivity, specificity, and area under the curve (AUC) with 95% confidence intervals (CI). We conducted a meta-regression to investigate individual test parameters and demographic variables.

RESULTS

We identified 15 eligible studies comprising 2090 individual assessments of BET. Among cohort studies, the AUC was 0.80 (95% CI: 0.61-0.91) with 70% sensitivity (95% CI: 52-83%) and 77% specificity (95% CI: 70-82%). In pooling cohort and case-control studies, the AUC was 0.84 (95% CI: 0.68-0.93) with 70% sensitivity (95% CI: 53-82%) and 81% specificity (95% CI: 75-86%). Subject positioning (seated vs. left lateral decubitus) did not significantly affect test performance in cohort (p = 0.82) or case-control (p = 0.43) analysis. Most studies evaluated 50-60 mL water insufflation. Test performance was not significantly affected by varying the maximum allowed expulsion time between 1 to 5 min. Age and gender likely accounted for significant study heterogeneity between studies. Choice of reference test, continent of study, and year of study did not significantly affect test performance.

DISCUSSION

We report an optimized BET protocol. The performance characteristics of BET could support its use as a point of service test to screen for dyssynergic defecation in chronically constipated subjects.

Short-Term Daily Intake of Polydextrose Fiber Does Not Shorten Intestinal Transit Time in Constipated Adults: A Randomized Controlled Trial

Chronic constipation (CC) remains a common gastrointestinal (GI) disorder that conveys a substantial healthcare burden. Expert guidelines recommend increasing fiber intake, yet the clinical evidence to support this needs strengthening for specific fibers. The aim was to evaluate changes in intestinal transit time and GI symptoms in CC patients who consumed polydextrose. In a randomized, double-blind, placebo-controlled trial, 128 adults with CC received 8 g or 12 g polydextrose, or placebo, daily for 4 weeks. Transit time, as primary outcome, was assessed by radiopaque marker distribution after 2-weeks intervention. Bowel habits, GI symptoms and quality of life (QOL) were assessed by questionnaire, including the Patient-Assessment of Constipation (PAC) Symptoms (SYM), and PAC-QOL. Following 2-weeks intervention, no reduction was seen in transit time in any group and following 2- or 4-weeks intervention, no improvements were seen in stool frequency or consistency in any group. After 2-weeks intervention with 8 g/day polydextrose an improvement was seen in the PAC-SYM rectal score (p = 0.041). After 4-weeks intervention both rectal (p = 0.049) and stool (p = 0.029) scores improved while improvement in the QOL satisfaction score did not reach significance (p = 0.071). Overall, the results suggest that 2-weeks consumption of 8 or 12 g/day polydextrose does not significantly improve physiological measures of gut function in CC adults. Longer term consumption may improve clinical measures, but further studies will be required to substantiate this.

Gender differences in the regulation of MLC20 phosphorylation and smooth muscle contraction in rat stomach

Evidence of sex-related differences in gastrointestinal (GI) functions has been reported in the literature. In addition, various GI disorders have disproportionate prevalence between the sexes. An essential step in the initiation of smooth muscle contraction is the phosphorylation of the 20-kDa regulatory myosin light chain (MLC₂₀) by the Ca²⁺/calmodulin-dependent myosin light chain kinase (MLCK). However, whether male stomach smooth muscle inherits different contractile signaling mechanisms for the regulation of MLC₂₀ phosphorylation from that in females has not been established. The present study was designed to investigate sex-associated differences in the regulation of MLC₂₀ phosphorylation and thus muscle contraction in gastric smooth muscle cells (GSMCs). Experiments were performed on GSMCs freshly isolated from male and female rats. Contraction of the GSMCs in response to acetylcholine (ACh), a muscarinic agonist, was measured via scanning micrometry in the presence or absence of the MLCK inhibitor, ML-7. Additionally, the protein levels of MLC₂₀, MLCK and phosphorylated MLC₂₀ were measured by ELISA. The protein levels of MLC₂₀ and MLCK were indifferent between the sexes. ACh induced greater contraction (P<0.05) as well as greater MLC₂₀ phosphorylation (P<0.05) in male GSMCs compared with female. Pretreatment of GSMCs with ML-7 significantly reduced the ACh-induced contraction (P<0.05) and MLC₂₀ phosphorylation (P<0.05) in the male and female cells, and notably, abolished the contractile differences between the sexes. In conclusion, MLC₂₀ phosphorylation and thus muscle contraction may be activated to a greater extent in male rat stomach compared with that in females.