Impaired esophageal function in patients with irritable bowel syndrome

The aim of the study was to determine prevalence of the signs and symptoms related to esophageal dysfunction in irritable bowel syndrome (IBS) patients, and to investigate sensorimotor function impairment based on the esophageal manometry study, thus to determine the correlation between them. The study included 30 patients with IBS, 14 of them with diarrhea (IBSd) and 16 with constipation (IBSc) as a predominant discomfort. Control group consisted of 30 healthy subjects. The patients were included in the study on the basis of the Rome criteria for IBS. In addition to thorough history and physical examination patient underwent esophagogastroduodenoscopy and esophageal manometry. The values of esophageal manometry obtained in healthy subjects served as controls in manometry studies. The patients with IBS suffered a great number of both colonic and extracolonic signs and symptoms, however, there was no statistically significant difference in the prevalence of particular symptoms between the two patient subgroups. In comparison with healthy subjects, the patients suffering from IBS showed pathologically altered values in the majority of parameters of esophageal motility. Comparison of the two subgroups of IBS patients according to esophageal motility characteristics yielded differences in only few of them. The results obtained in the study could explain why the patients with IBS quite commonly complain of the symptoms related to upper gastrointestinal tract, such as heartburn and chest pain of noncardiac genesis. The results also suggest that the IBS might be associated with considerably more extensive smooth muscle or innervation changes than presumed before.     

Endocannabinoid and Cannabinoid-Like Fatty Acid Amide Levels Correlate with Pain-Related Symptoms in Patients with IBS-D and IBS-C: A Pilot Study

Aims

Irritable bowel syndrome (IBS) is a functional gastrointestinal (GI) disorder, associated with alterations of bowel function, abdominal pain and other symptoms related to the GI tract. Recently the endogenous cannabinoid system (ECS) was shown to be involved in the physiological and pathophysiological control of the GI function. The aim of this pilot study was to investigate whether IBS defining symptoms correlate with changes in endocannabinoids or cannabinoid like fatty acid levels in IBS patients.

Methods

AEA, 2-AG, OEA and PEA plasma levels were determined in diarrhoea-predominant (IBS-D) and constipation-predominant (IBS-C) patients and were compared to healthy subjects, following the establishment of correlations between biolipid contents and disease symptoms. FAAH mRNA levels were evaluated in colonic biopsies from IBS-D and IBS-C patients and matched controls.

Results

Patients with IBS-D had higher levels of 2AG and lower levels of OEA and PEA. In contrast, patients with IBS-C had higher levels of OEA. Multivariate analysis found that lower PEA levels are associated with cramping abdominal pain. FAAH mRNA levels were lower in patients with IBS-C.

Conclusion

IBS subtypes and their symptoms show distinct alterations of endocannabinoid and endocannabinoid-like fatty acid levels. These changes may partially result from reduced FAAH expression. The here reported changes support the notion that the ECS is involved in the pathophysiology of IBS and the development of IBS symptoms.     

Composition and temporal stability of gastrointestinal microbiota in irritable bowel syndrome--a longitudinal study in IBS and control subjects

Irritable bowel syndrome (IBS) is a common intestinal disorder that includes continuous or recurrent intestinal pain and discomfort and altered bowel habits. The pathophysiology of IBS is incompletely understood, but it may involve an altered intestinal microbiota. The aim of the present study was to compare the composition and temporal stability of faecal microbiota of IBS patients and healthy controls by applying culture-based techniques and PCR-DGGE analysis. No difference in the prevalence or mean culturable manners of bacteroides, bifidobacteria, spore-forming bacteria, lactobacilli, enterococci or yeasts were observed between the IBS and the control groups, whereas slightly higher numbers of coliforms as well as an increased aerobe:anaerobe ratio was observed in the IBS group. PCR-DGGE revealed more temporal instability in the predominant bacterial population of IBS subjects than in controls. In 9 out of 21 IBS subjects and 5 out of 17 controls the PCR-DGGE profiles obtained from the samples of the same individual on different occasions (sampling points 0, 3 and 6 months) were clearly different. However, the instability in some of the IBS subjects could partly be explained by the antibiotic consumption during the study. The present study suggests that instability of intestinal microbiota may be involved in IBS. However, further studies are needed to associate the instability with specific IBS symptoms or with specific bacterial groups and species.     

IBS--review and what's new

Irritable bowel syndrome (IBS) is a highly prevalent gastrointestinal motility disorder broadly characterized by abdominal pain/discomfort associated with altered bowel habits. The chronic and bothersome nature of IBS symptoms often negatively affects patient quality of life and activity level and places a substantial economic burden on patients and the healthcare system. Advances in research have led to a greater understanding of the underlying pathophysiology of IBS, particularly regarding the role serotonin plays in the gastrointestinal tract; the development of stepwise, symptom-based diagnostic strategies that allow for a diagnosis of IBS to be made without the need for extensive laboratory testing; and the development of treatment options targeting underlying pathophysiologic mechanisms that provide relief of the multiple symptoms associated with IBS. This review highlights recent advances in research and discusses how these findings can be applied to daily clinical practice.     

Effects of β-(1,3-1,6)-D-glucan on irritable bowel syndrome-related colonic hypersensitivity

Irritable bowel syndrome (IBS) is a gastrointestinal disorder characterized by chronic abdominal pain associated with altered bowel habits. Since the prevalence of IBS is very high and thus, involves elevated health-care costs, treatment of this condition by methods other than prescribed medicines could be beneficial. β-(1,3)-D-glucan with β-(1,6) branches (β-glucan) has been used as a nutritional supplement for many years. In this study, we examined the effect of β-glucan on fecal pellet output and visceral pain response in animal models of IBS. Oral administration of β-glucan suppressed the restraint stress- or drug-induced fecal pellet output. β-Glucan also suppressed the visceral pain response to colorectal distension. These results suggest that β-glucan could be beneficial for the treatment and prevention of IBS.     

肠道微生物代谢物在肠易激综合征中的研究进展

肠易激综合征(irritable bowel syndrome, IBS)是常见的胃肠道功能障碍疾病,以腹痛、腹胀、排便习惯改变等为典型临床症状。尽管IBS病因复杂且发病机制并未完全阐明,但越来越多的文献报道其发病与微生物-肠-脑轴调控失常密切相关。本文以肠道微生物衍生的代谢物神经递质、短链脂肪酸和胆汁酸代谢物为切入点,对其在内脏敏感、腹痛、腹泻和精神心理障碍等IBS症状发展中的作用进行系统综述,为以代谢物转化细菌为靶点治疗IBS提供理论支撑。     

Attenuation of the colorectal tonic reflex in female patients with irritable bowel syndrome

Alterations in normal intestinointestinal reflexes may be important contributors to the pathophysiology of irritable bowel syndrome (IBS). Our aims were to compare the rectal tonic responses to colonic distension in female IBS patients with predominant constipation (IBS-C) and with predominant diarrhea (IBS-D) to those in healthy females, both fasting and postprandially. Using a dual barostat assembly, 2-min colonic phasic distensions were performed during fasting and postprandially. Rectal tone was recorded before, during, and after the phasic distension. Colonic compliance and colonic sensitivity in response to the distension were also evaluated fasting and postprandially. Eight IBS-C patients, 8 IBS-D patients, and 8 age- and sex-matched healthy subjects (group N) participated. The fasting increments in rectal tone in response to colonic distension in both IBS-C (rectal balloon volume change -4.6 +/- 6.1 ml) and IBS-D (-7.9 +/- 4.9 ml) were significantly reduced compared with group N (-34 +/- 9.7 ml, P = 0.01). Similar findings were observed postprandially (P = 0.02). When adjusted for the colonic compliance of individual subjects, the degree of attenuation in the rectal tonic response in IBS compared with group N was maintained (fasting P = 0.007; postprandial P = 0.03). When adjusted for colonic sensitivity there was a trend for the attenuation in the rectal tonic response in IBS patients compared with group N to be maintained (fasting P = 0.07, postprandial P = 0.08). IBS patients display a definite attenuation of the normal increase in rectal tone in response to colonic distension (colorectal reflex), fasting and postprandially. Alterations in colonic compliance and sensitivity in IBS are not likely to contribute to such attenuation.     

Irritable bowel syndrome: a review on the role of intestinal protozoa and the importance of their detection and diagnosis

Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder in which abdominal pain is associated with a defect or a change in bowel habits. Gut inflammation is one of the proposed mechanisms of pathogenesis. Recent studies have described a possible role for protozoan parasites, such as Blastocystis hominis and Dientamoeba fragilis, in the etiology of IBS. Dientamoeba fragilis is known to cause IBS-like symptoms and has a propensity to cause chronic infections but its diagnosis relies on microscopy of stained smears, which many laboratories do not perform, thereby leading to the misdiagnosis of dientamoebiasis as IBS. The role of B. hominis as an etiological agent of IBS is inconclusive, due to contradictory reports and the controversial nature of B. hominis as a human pathogen. Although Entamoeba histolytica infections occur predominately in developing regions of the world, clinical diagnosis of amebiasis is often difficult because symptoms of patients with IBS may closely mimic those patients with non-dysenteric amoebic colitis. Clinical manifestations of Giardia intestinalis infection also vary from asymptomatic carriage to acute and chronic diarrhoea with abdominal pain. These IBS-like symptoms can be continuous, intermittent, sporadic or recurrent, sometimes lasting years without correct diagnosis. It is essential that all patients with IBS undergo routine parasitological investigations in order to rule out the presence of protozoan parasites as the causative agents of the clinical signs.     

Influence of the requirement for abdominal pain in the diagnosis of irritable bowel syndrome with constipation (IBS-C) under the Rome IV criteria using data from a large Japanese population-based internet survey

Background

Rome III was revised to Rome IV in May 2016. One important change in the Rome IV criteria is that abdominal pain must be present for a diagnosis of irritable bowel syndrome (IBS). Under Rome III, in contrast, patients with abdominal discomfort only could be diagnosed with IBS, but these cases under Rome IV are now classified as unspecified functional bowel disorder (FBD). In a simple comparison of Rome III and Rome IV, it is unclear whether this difference reflects the influence of symptomatic frequency or the presence of abdominal pain. In particular, the influence of abdominal pain restriction on the diagnosis of IBS with predominant constipation (IBS-C) in the Rome IV criteria is largely unknown.

Methods

We reclassified subjects from a Japanese internet survey experiencing abdominal pain or discomfort at least one day each week as surrogate Rome III IBS-C subjects. Among them, we then reclassified subjects experiencing abdominal pain as surrogate Rome IV IBS-C subjects and subjects not experiencing abdominal pain as surrogate Rome IV FBD subjects. Symptoms were quantified and compared between the two groups.

Results

The surrogate Rome IV IBS-C subjects felt a significantly higher degree of anxiety in their daily lives (p?<?0.001) compared with the surrogate Rome IV FBD subjects. The combined female and 20–49?years surrogate Rome IV IBS-C subjects felt a higher degree of anxiety in their daily lives (p?<?0.05) than the respective Rome IV FBD subjects.

Conclusions

These results suggest that female IBS-C patients aged 20–49?years with abdominal pain in Rome IV have more anxiety than those without abdominal pain in Rome III. Changes in the diagnostic criteria from Rome III to Rome IV will better identify candidates for the biopsychosocial approach.

Trial registration

Although this survey was an anonymous internet survey, we obtained informed consent for the study as an online response. The disclosure of this study was approved by the Ethics Committee of Tohoku University Graduate School of Medicine (approval number: 2015–1-405).

     

Proteomic analysis of colonic mucosa in a rat model of irritable bowel syndrome

Irritable bowel syndrome (IBS) is one of the most common functional disorders of the gastrointestinal tract. It is characterized by abdominal pain and changes in bowel habits. Various studies have investigated the pathophysiologic processes underlying IBS, but the mechanism remains poorly understood. In the present study, we established an IBS model and identified differentially expressed proteins in colon tissue of IBS rats compared with healthy controls by 2‐D gel electrophoresis, MALDI‐TOF‐MS, and Western blot analysis. Our results showed that 13 of the 1396 protein spots on 2‐D gel were differently expressed between the IBS and control groups. Ontological analysis of these proteins revealed primary roles in catalytic activity (protein disulfide‐isomerase A3, glyoxalase I, cathepsin S, α‐enolase), structural support (cytokeratin 8), antioxidant activity (peroxiredoxin‐6), protein binding (transgelin, serpin peptidase inhibitor B5), and signal transduction (40S ribosomal protein SA). Protein disulfide‐isomerase A3 and cytokeratin 8 overexpression in IBS were confirmed by Western blot. The findings indicate that multiple proteins are involved in IBS processes that influence intestinal tract immunity, inflammation, and nerve regulation. Our study provides useful candidate genes and proteins for further investigation.     

Cytokines and irritable bowel syndrome: Where do we stand?

Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder, which presents with one or more gastrointestinal symptoms without any structural or organic abnormality. The etiology and pathophysiological mechanisms of IBS remain uncertain. Residual or reactivated inflammation at the molecular level is considered the underlying mechanism of post-infectious IBS. On the other hand, genetic variations in the immunological components of the body, including cytokine gene polymorphisms, are proposed as a potential mechanism of IBS even in patients without previous gastrointestinal infection. Several studies have suggested imbalanced cytokine signaling as an etiology for IBS. In this review, recent findings on cytokine profiles and cytokine gene polymorphisms in patients with IBS are described and the role of cytokines in animal models of IBS is discussed.     

慢性应激致肠易激综合征大鼠模型的建立与评价

目的建立一种模拟肠易激综合征临床症状的动物模型,为相关药物的研究提供实验基础。方法采用孤养附加慢性不可预见性刺激建立IBS模型,每只大鼠受到的刺激因子包括:24h禁水、24h禁食、昼夜颠倒、4℃冰水游泳15min、45℃高温5min、钳尾致痛1min、束缚制动5～8h、高速震荡15min等共8种,每种刺激因子出现5次,共40d。用腹部回撤反射压力阈值(AWR)和排便粒数检测动物的内脏感觉和胃肠运动功能变化;用敞箱行为评分和蔗糖水偏嗜度评价动物神经精神活动变化。结果造模2～3周腹部回撤反射压力阈值明显降低,排便粒数明显增加;造模3～4周模型组动物敞箱实验行为评分和蔗糖水偏嗜度明显降低。造模40d时,上述变化趋势仍存在。结论慢性应激加孤养可诱导动物胃肠运动亢进、内脏感觉致敏和神经精神活动的改变,模拟IBS患者的临床特征,可作为一种有效的IBS动物模型,用于评价相关药物。     

西甲硅油联合枯草杆菌肠球菌对肠易激综合征的疗效观察

目的:探讨西甲硅油乳剂联合枯草杆菌肠球菌二联活菌肠溶胶囊(美常安)在肠易激综合征(IBS)治疗中的临床效果。方法:将2014年1月至2015年10月收治的180例IBS患者随机分为西甲硅油乳剂联合枯草杆菌肠球菌二联活菌治疗组92例和单药枯草杆菌肠球菌二联活菌治疗对照组88例,治疗4周后随访观察两组患者的治疗总有效率、不同胃肠症状的治疗有效率,以及不同型IBS患者的胃肠症状评分。结果:IBS治疗组的治疗总有效率为88.0%,明显高于对照组70.5%(P0.05)。治疗4周后腹胀和排便次数改善的有效率分别为94.6%和78.3%明显高于对照组的77.3%和60.2%(P0.05),但两组在腹痛和排便性状改善方面比较无明显差异(P0.05)。对两组不同胃肠症状评分结果:显示同组同型IBS治疗4周后胃肠症状评分均明显低于治疗前(P0.05)治疗有效。但两组同型IBS患者的治疗后胃肠症状评分比较时,仅在便秘型IBS患者差异明显(P0.05)。结论:西甲硅油乳剂联合枯草杆菌二联活菌肠溶胶囊对肠易激综合征(IBS)患者治疗有效,对缓解腹胀和改善排便次数上治疗效果尤为明显,对IBS便秘型患者的胃肠症状恢复疗效最佳。     

Blastocystis Is Associated with Decrease of Fecal Microbiota Protective Bacteria: Comparative Analysis between Patients with Irritable Bowel Syndrome and Control Subjects

Blastocystis is a protistan parasite living in the digestive tract of many animals, including humans. This highly prevalent intestinal parasite is suspected to be linked to Irritable Bowel Syndrome (IBS), a chronic functional bowel disorder. Here, we first compared the prevalence of Blastocystis among 56 IBS patients (40 IBS with constipation (IBS-C), 9 IBS with diarrhea (IBS-D), 4 mixed IBS (IBS-M) and 3 unsubtyped IBS (IBS-U) according to the Rome III criteria) and 56 control (i.e. without any diagnosed chronic or acute gastrointestinal disorder) subjects. The highest prevalence of Blastocystis spp. was observed in the IBS group, but was only statistically significant in men (36.8% in the IBS group versus 4.8% in the control group). We then conducted a meta-analysis including epidemiological studies attempting to determine whether Blastocystis carriage could be linked to IBS, and highlighted that IBS patients had a relative risk of 2.34 to be infected by Blastocystis when compared to non-IBS subjects. We also looked for Dientamoeba fragilis, which is often associated with IBS, and identified this parasite only in some IBS patients (n = 6/56). Several studies provided evidence for a major role of the gut microbiota in the pathophysiology of IBS. Thus, we investigated the possible impact of Blastocystis carriage on the enteric bacterial community through quantification of 8 major bacterial groups from the enteric flora. Our data indicated that men with IBS-C had a significant decrease in Bifidobacterium sp. when infected by Blastocystis. Interestingly, in control subjects (i.e. without any gastrointestinal disorder) positive for Blastocystis, Faecalibacterium prausnitzii, which is known for its anti-inflammatory properties, was significantly decreased in men. Our results support the hypothesis that Blastocystis might be linked to the pathophysiology of IBS-C and intestinal flora imbalance.     

Abdominal bloating is the most bothersome symptom in irritable bowel syndrome with constipation (IBS-C): a large population-based Internet survey in Japan

Background

Abdominal bloating is a common symptom in patients with irritable bowel syndrome with constipation (IBS-C). However, it is not included among the required items in the Rome III diagnostic criteria for IBS. Little is known about an impact of abdominal bloating seen in patients with IBS-C. Using a large population-based sample, the aim of the present study was to investigate what is the most bothersome symptom in subjects with IBS-C.

Methods

An Internet survey of 30,000 adults drawn from the general public throughout Japan was conducted to identify subtypes of IBS using the Rome III diagnostic questionnaire. Consecutively, the screened subjects with IBS-C and the same number of age- and sex-matched non-IBS subjects who were randomly selected as controls were asked to answer a questionnaire on the degree of anxiety they experienced in their daily lives, thoughts about bowel habit, and their dominant gastrointestinal symptoms together with exacerbation factors (for IBS-C only).

Results

The screening survey showed that the prevalence of overall IBS was 16.5 % (female 17.4 %, male 15.5 %) and that 2.8 % met the criteria for IBS-C, 4.5 % for IBS with diarrhea (IBS-D) and 8.2 % for mixed IBS (IBS-M). Seven hundred and fifty-nine of 835 (90.9 %) subjects with IBS-C and 746 of 830 (89.9 %) control subjects completed the consecutive questionnaire. IBS-C subjects felt a higher degree of anxiety in their daily lives (p?<?0.01) and considered bowel habit to be an indicator of health (p?<?0.01) to a greater extent than control subjects. In IBS-C, the degree of anxiety was significantly associated with abdominal discomfort (p?<?0.01), pain (p?<?0.01) and bloating (p?=?0.02), but not with the frequency of bowel habit (p?>?0.1). Abdominal bloating was the most bothersome symptom (27.5 %), which was more likely to occur after a meal (52.2 %), at work/school (29.2 %) and during times of stress (26.8 %). Only 4.5 % of IBS-C subjects reported abdominal pain as the ‘most bothersome’ symptom.

Conclusions

A large population-based Internet survey suggests that abdominal bloating has a great impact on the daily lives of subjects diagnosed with IBS-C. Not only bowel movement/abdominal pain but also abdominal bloating should be evaluated in patients with IBS-C.

     

Clinical and anorectal motility features in chronically constipated children

Constipation is a common problem in children. It can be a symptom of functional disorder in majority of cases, but sometimes a serious organic disease is a cause of constipation. Anorectal manometry plays an important role in the diagnostic procedure. It can be presumed that some values of manometric parameters could be very useful in treatment plan. The aim of this study was to confirm or exclude such limits in manometric finding, to make a plan of the therapy more accurate. Therefore the group of 81 constipated children was investigated. There were 58 patients suffering from functional constipation and 23 with organic disorders. The age of the patients was 3 to 15 years. Scoring system was applied to estimate severity of constipation and anorectal manometry was performed. Our results did not show significant correlation between clinical symptoms and signs and the values that we obtained using anorectal manometry. But, we recommend anorectal manometry because it is a safe method and contributes to clarify the diagnosis, which is very important for treatment plan.     

Role of Toll Like Receptors in Irritable Bowel Syndrome: Differential Mucosal Immune Activation According to the Disease Subtype

Background

The irritable bowel syndrome (IBS) is a functional gastrointestinal disorder whose pathogenesis is not completely understood. Its high prevalence and the considerable effects on quality of life make IBS a disease with high social cost. Recent studies suggest that low grade mucosal immune activation, increased intestinal permeability and the altered host-microbiota interactions that modulate innate immune response, contribute to the pathophysiology of IBS. However, the understanding of the precise molecular pathophysiology remains largely unknown.

Methodology and Findings

In this study our objective was to evaluate the TLR expression as a key player in the innate immune response, in the colonic mucosa of IBS patients classified into the three main subtypes (with constipation, with diarrhea or mixed). TLR2 and TLR4 mRNA expression was assessed by real time RT-PCR while TLRs protein expression in intestinal epithelial cells was specifically assessed by flow cytometry and immunofluorescence. Mucosal inflammatory cytokine production was investigated by the multiplex technology. Here we report that the IBS-Mixed subgroup displayed a significant up-regulation of TLR2 and TLR4 in the colonic mucosa. Furthermore, these expressions were localized in the epithelial cells, opening new perspectives for a potential role of epithelial cells in host-immune interactions in IBS. In addition, the increased TLR expression in IBS-M patients elicited intracellular signaling pathways resulting in increased expression of the mucosal proinflammatory cytokines IL-8 and IL1β.

Conclusions

Our results provide the first evidence of differential expression of TLR in IBS patients according to the disease subtype. These results offer further support that microflora plays a central role in the complex pathophysiology of IBS providing novel pharmacological targets for this chronic gastrointestinal disorder according to bowel habits.     

The influence of the two different light intensities duringthe daytime on the colon motility in patients with irritable bowel syndrome (IBS): a preliminary report

Irritable bowel syndrome (IBS) is the most frequent functional disorder of the gastrointestinal tract, with great economical impact. The etiology and pathogenesis of the disease are unclear. Among patients seeking medical attention for IBS, 70 - 90% have psychiatric co-morbidity, most commonly major depression. In this study we test the influence of bright light on colon motility and subjectively felt symptoms. Eight IBS patients participated in the experiment. The passage rate was evaluated twice for every person: (1) after three days of exposure to bright light -3000 lux (from 8:00 to 18:00), (2) after three days exposure to dim light -100 lux (from 8:00 to 18:00). The comparison of colonic time in IBS patients point to differences in the elimination of markers, depending on experimental light conditions. After bright light conditions a tendency is observed to slower elimination of markers in the IBS-diarrhoea patients, and to a quicker elimination in the IBS-constipated patients. According to subjective feeling, all IBS patients reported an improvement in bowel function and relief of pain after bright but not after dim light application. Results of this preliminary study suggest that phototherapy might be a valuable addition to the conventional treatment of IBS.     

Candidate genes and sensory functions in health and irritable bowel syndrome

Adrenergic and serotonergic (ADR-SER) mechanisms alter gut (GI) function; these effects are mediated through G protein transduction. Candidate genetic variations in ADR-SER were significantly associated with somatic scores in irritable bowel syndrome (IBS) and gastric emptying but not small bowel or colonic transit. Our aim was to assess whether candidate ADR-SER genes are associated with motor and sensory GI functions in IBS and subgroups on the basis of bowel dysfunction. In 122 patients with IBS and 39 healthy controls, we assessed gastrointestinal somatic symptoms and affect by validated questionnaires. We measured: gastric volume (GV), maximum tolerated volume, rectal compliance, sensation thresholds and ratings, and genetic variations including alpha2A (C-1291G), alpha2C (Del 332-325), GNbeta3 (C825T), and 5-HTTLPR. Demographics and genotype distributions were similar in the patients with IBS subgrouped on bowel function. There were significant associations between 5-HTTLPR SS genotype and absence of IBS symptoms and between 5-HTTLPR LS/SS genotype and increased rectal compliance and increased pain ratings, particularly at 12 and 24 mmHg distensions. GNbeta3 was associated only with fasting GV; we did not detect associations between alpha2A genotype and the gastrointestinal sensory or motor functions tested. We concluded that 5-HTTLPR LS/SS genotype is associated with both increased pain sensation and increased rectal compliance though the latter effect is unlikely to contribute to increased pain sensation ratings with LS/SS genotype. The data suggest the hypotheses that the endophenotype of visceral hypersensitivity in IBS may be partly related to genetic factors, and the association of GNbeta3 with fasting GV may explain, in part, the reported association of GNbeta3 with dyspepsia.     

Towards positive diagnosis of the irritable bowel.

A questionnaire to establish the presence of 15 symptoms thought to be typical of the irritable bowel syndrome (IBS) was given to 109 unselected patients referred to gastroenterology or surgery clinics with abdominal pain or a change in bowel habit or both. Review of case records 17--26 months later established a definite diagnosis of IBS in 32 patients and of organic disease in 33. Four symptoms were significantly more common among patients with IBS--namely, distension, relief of pain with bowel movement, and looser and more frequent bowel movements with the onset of pain. Mucus and a sensation of incomplete evacuation were also common in these patients. The more of these symptoms that were present the more likely was it that the patient''s pain or altered bowel habit, or both, was due to IBS. We conclude that a careful history can increase diagnostic confidence and reduce the amount of investigation in many patients with chronic abdominal pain.