Dysmotility of the small intestine in irritable bowel syndrome

Iron deficiency suppresses ileal nitric oxide synthase activity

Intestinal motility disorders are more common in women of childbearing age who are prone to iron deficiency anemia. The neurotransmitters nitric oxide (NO) and acetylcholine (ACh) play a key role in ileal smooth muscle relaxation and contraction, respectively. Iron-containing heme is known to be a cofactor for nitric oxide synthase (NOS), the enzyme responsible for NO production. Therefore we tested the hypothesis that iron deficiency would downregulate ileal NOS activity without affecting the ileum's response to ACh. Twelve adult female prairie dogs were fed either an iron-supplemented (Fe+) (200 ppm) (n = 6) or an iron-deficient (Fe-) (8 ppm) (n = 6) diet for 8 weeks. Ileal circular muscle strips were harvested to measure responses to ACh and electrical field stimulation. Under nonadrenergic noncholinergic (NANC) conditions, Nomega-nitro-L-arginine (L-NNA), an NOS inhibitor, and VIP(10-28), a vasoactive intestinal peptide (VIP) inhibitor, were added prior to electrical field stimulation. NANC inhibitory responses are expressed as a percentage of optimal relaxation from EDTA. The excitatory response to ACh was similar in both groups (1.1 +/- 0.3 N/cm(2) vs. 1.5 +/- 0.3 N/cm(2), P = 0.45). The inhibitory response to electrical field stimulation under NANC conditions was greater in the Fe+ group (34.7 +/- 2.9%) compared to the Fe- group (23.9 +/- 3.2%; P<0.01). L-NNA eliminated the inhibitory response in the Fe+ group (0.02 +/- 0.02%) but not in the Fe- group (8.38 +/- 2.15%; P <0.01). VIP(10-28) led to greater relaxation in the Fe+ animals (45.8 +/- 6.6%) than in the Fe- animals (23.4 +/- 5.8%; P <0.05). Both L-NNA and VIP(10-28) had no inhibitory response (0.02 +/- 0.02%) in the Fe+ animals, whereas the Fe- animals had some residual inhibition (2.54 +/- 1.04%; P <0.05). These data suggest that ileal NANC relaxation is due to NOS and that iron deficiency results in (1) decreased NANC relaxation, (2) a compensatory relaxation due to a non-NOS, non-VIP mechanism, and (3) a normal excitatory response. We conclude that iron deficiency suppresses ileal NOS activity.

Functional abdominal pain in the elderly

Although aging per se affects function throughout the gut, particularly after age 70, the observed changes are relatively modest and often asymptomatic, perhaps because of the vast reserve of neuromuscular functional elements in the gut. The proximal esophagus, anus, and pelvic floor are possible exceptions to this generalization, and the combination of aging and factors such as minor strokes or obstetric damage often results in dysphagia, constipation, or fecal incontinence. Managing elderly patients with functional abdominal pain demands clinical acumen, tact, understanding, and patience. Further studies are required to elucidate the consequences of aging on gastrointestinal sensorimotor function at several levels of the digestive tract. With the expected explosion in the proportion of the population older than age 75, this field should become a high priority for clinical and research efforts. Also required will be a major campaign to educate patients and practitioners and multidisciplinary collaborations among primary care practitioners, gastroenterologists, psychologists, and physiatrists to provide optimal pain management in the elderly.

Enhanced intestinal motor response to cholecystokinin in post-Nippostrongylus brasiliensis-infected rats: modulation by CCK receptors and the vagus nerve

The jejunal inflammation induced in rats by the nematode Nippostrongylus brasiliensis is followed by intestinal neuroimmune alterations including mast cell hyperplasia and nerve remodelling. On the other hand, cholecystokinin (CCK) plays a pivotal role in the regulation of intestinal motility. The aim of this study was to determine whether the intestinal motor response to CCK is altered 30 days after infection by N. brasiliensis. Thus, CCK-8 (50 microg kg(-1) intraperitoneally) disrupted the pattern of jejunal migrating myoelectric complexes for a longer time in postinfected rats (95.5 +/- 3.5 min) than in controls (48.1 +/- 5.1 min). This enhanced jejunal response was also found after oral administration of the potent releaser of endogenous CCK, soybean trypsin inhibitor. In contrast, no alteration of the inhibition of colonic motility by CCK administration was observed. The increased responsiveness of jejunal motility to CCK persisted after mast cell stabilisation or depletion but was prevented by atropine, devazepide and L-365260 (CCK-A and CCK-B receptor antagonists, respectively) and vagotomy. These results indicate that neuroimmune alterations after N. brasiliensis infection lead to an increased intestinal motility response to CCK that involves a cholinergic mediation, a vagal pathway and alterations in intestinal CCK-A and CCK-B receptors.

Intestinal and colonic motor alterations associated with irradiation-induced diarrhoea in rats

Localized application of ionizing radiation to the gastrointestinal tract frequently elicits responses, which include diarrhoea. The origin of this symptom is not clear but has been attributed to loss of epithelial integrity, together with alterations in motility and increased secretion. The purpose of this study was to examine whether a 10 Gy abdominal gamma irradiation leads to an inflammatory reaction, and to compare intestinal and colonic motility in controls and abdominally irradiated rats 1, 3 and 7 days after irradiation, using an electromyographic technique. The motility parameters analysed were the frequency and velocity of propagation of migrating myoelectric complexes (MMC) in the jejunum and colonic spike activity (long spike bursts; LSB) per 10 min in fasted rats. The MMC frequency was significantly reduced on days 1 and 7 after irradiation and the MMC pattern was markedly disrupted on day 3. The frequency of colonic LSB was significantly reduced on days 1, 3 and 7. Mouth to anus transit was significantly accelerated on day 3 only and diarrhoea was observed at this time. Myeloperoxidase activity in the jejunum and colon was also increased on this day only. It is concluded that irradiation-induced diarrhoea occurs contemporaneously with disruption of MMC in the small intestine.

An exaggerated sensory component of the gastrocolonic response in patients with irritable bowel syndrome

BACKGROUND/AIMS

Visceral hypersensitivity is a feature of the irritable bowel syndrome (IBS). Postprandial symptoms are common in these patients. The effects of nutrients on colonic perception in IBS are incompletely understood.

SUBJECTS

We studied 13 healthy subjects and 16 patients with IBS-eight had diarrhoea predominant (IBS-D) and eight constipation predominant (IBS-C) IBS.

METHODS

Colonic perception thresholds to balloon distension and viscerosomatic referral pattern were assessed before and after duodenal infusion of lipid or saline, respectively. At the end of the infusions, plasma levels of gastrointestinal peptides were determined.

RESULTS

Lipids lowered the thresholds for first sensation, gas, discomfort, and pain in the IBS group but only for gas in the control group. The percent reduction in thresholds for gas and pain after lipids was greater in the IBS and IBS-D groups but not in the IBS-C group compared with controls. IBS patients had an increased area of referred discomfort and pain after lipids compared with before infusion whereas the referral area remained unchanged in controls. No group differences in colonic tone or compliance were observed. In both groups higher levels of cholecystokinin, pancreatic polypeptide, peptide YY, vasoactive intestinal polypeptide, and neuropeptide Y were seen after lipids. Motilin levels were higher in patients and differences in the subgroups were observed. Levels of corticotrophin releasing factor were lower in the constipated group than in the diarrhoea group.

CONCLUSIONS

Postprandial symptoms in IBS patients may be explained in part by a nutrient dependent exaggerated sensory component of the gastrocolonic response.

The association between Helicobacter pylori infection and functional dyspepsia in patients with irritable bowel syndrome

OBJECTIVE

Irritable bowel syndrome (IBS) is associated with an exaggerated response to a variety of physiological and nonphysiological gastrointestinal stimuli. Many patients with IBS also have functional dyspepsia. Our aim was to examine the hypothesis that Helicobacter pylori (H. pylori) infection may predispose IBS patients to functional dyspepsia.

METHODS

In 69 IBS patients, dyspeptic symptoms, H. pylori status, and sociodemographic and psychological variables (perceived stress, trait anxiety, and depression) were assessed. Sociodemographic and psychological variables were also evaluated in 52 control subjects.

RESULTS

Mean scores for perceived stress (17.1 +/- 6.0 vs 14.9 +/- 6.0, p = 0.05), trait anxiety (45.6 +/- 9.1 vs 41.1 +/- 7.8, p = 0.004) and depression (9.9 +/- 8.4 vs 5.0 +/- 5.5, p = 0.0002) were higher in IBS patients than in controls. In all, 33 of the 69 patients (47.8%) had H. pylori infection, and this was associated with relevant symptoms of epigastric pain (odds ratio [OR] = 6.77, 95% confidence interval [CI] 1.89-24.3) and postprandial upper abdominal fullness (OR = 4.23, 95% CI 1.38-13.2). H. pylori infection and female gender were independent predictors of the presence of relevant dyspepsia (OR = 8.31, 95% CI 2.35-29.5 and 6.06, 95% CI 1.71-21.5, respectively). Symptom intensity was associated with the level of perceived stress (total relevant symptom number > or =3 vs <3, OR = 1.16 per point on a 40-point perceived stress scale, 95% CI 1.01-1.34).

CONCLUSIONS

In IBS patients, the presence of dyspepsia is associated with H. pylori infection, female gender, and perceived stress.

Clinical use of manometry for the diagnosis of intestinal motor abnormalities

Digestive symptoms suggestive of intestinal motor disorders, such as abdominal pain and distension, fullness, vomiting, constipation and diarrhoea, are very common and non-specific, and may be clinical manifestations of both organic and functional diseases. Both radiology and endoscopy are important in the diagnosis of structural gastrointestinal lesions that can affect motility and offer indirect signs of impaired gastrointestinal functions, but the diagnosis of gut motility disorders currently relies on the manometric assessment of contractile activities. Small bowel manometry helps to identify normal motility features and consequently to identify abnormal motor patterns. Small bowel manometry can help to differentiate mechanical obstruction from pseudo-obstruction and neurogenic from myogenic motor disorders. Manometry is an invasive technique which is not well accepted by patients and requires specific skills from investigators. Also, manometric assessment is limited to referral centres with a specific interest in the field of digestive functions, in general, and motility, in particular. Only patients who remain undiagnosed after extensive traditional work-up and fail repeated courses with medical therapy should be referred for the manometric test. Understanding the underlying pathophysiologic mechanisms of abnormal motility and developing new therapies are the goals of the current research in this fascinating field of medicine.

Patient subgroups in irritable bowel syndrome that can be defined by symptom evaluation and physical examination

Subgroups of patients with irritable bowel syndrome (IBS) are likely to respond differently to existing and evolving therapies. The following criteria for subgrouping may be considered: (1) Patients with different predominant bowel habits respond differently to treatment (antidepressants, 5HT3-antagonists, psychotherapy). (2) Postprandial exacerbation of pain or other gastrointestinal symptoms is seen in approximately half of patients with IBS and may identify patients who are more responsive to some classes of drugs (e.g., those targeted at motility). (3) Women appear to respond differently from men to 5HT3-antagonists, and there may be gender differences in gastrointestinal physiology. (4) There is more overlap in the diagnosis of functional dyspepsia and IBS than would be predicted by chance, and both are associated with hyperalgesia to intraluminal distention.

Principles of applied neurogastroenterology: physiology/motility-sensation

Many of the symptoms characteristic of the functional gastrointestinal disorders (FGID) are consistent with dysfunction of the motor and/or sensory apparatus of the digestive tract. Those aspects of sensorimotor dysfunction most relevant to the FGID include alterations in: gut contractile activity; myoelectrical activity; tone and compliance; and transit, as well as an enhanced sensitivity to distension, in each region of the gastrointestinal tract. Assessment of these phenomena involves a number of techniques, some well established and others requiring further validation. Using such techniques, researchers have reported a wide range of alterations in sensory and in motor function in the FGID. Importantly, however, relationships between such dysfunction and symptoms have been relatively weak, and so the clinical relevance of the former remains unclear. Moreover, the proportions of patients in the various symptom subgroups who display dysfunction, and the extent and severity of their symptoms, require better characterization. On a positive note, progress is occurring on several fronts, especially in relation to functional dyspepsia and irritable bowel syndrome, and based on the data gathered to date, a number of areas where further advances are required can be highlighted.

The patterns of small bowel motility: physiology and implications in organic disease and functional disorders

The physiology and pathophysiology of small bowel motility are reviewed with particular focus on the motility patterns and periods that are detected by intraluminal manometry. Motility patterns are groups of phasic pressure waves resulting from contractions of the circular muscle layer of the small bowel that are organized by the enteric nervous system. Phase III of the migrating motor complex, the hallmark of the fasting motility period, thus reflects enteric neuromuscular function. Response to meal challenge also involves the CNS, reflexes beyond the gut and endocrine responses. Although specific disease diagnosis cannot be made by motility studies of the small bowel, the functional integrity is revealed. The normal occurrence of the essential patterns and periods of motility and the absence of distinctly abnormal patterns evidence preserved function, whereas the opposite indicates clinically significant dysmotility. Certain motility patterns are occasionally seen both in health and disease, and increased prevalence indicates a moderate dysfunction of yet unclear significance. Bacterial overgrowth with Gram-negative bacilli is the consequence of severe small bowel dysmotility, and a diagnosis that can be predicted by a motility study. Testing can be useful in the clinical management of paediatric and adult patients also by predicting the prognosis and response to enteral nutrition and medical therapy. Further studies are, however, needed to take full advantage of motility testing in clinical practise.

Abdominal symptoms are not related to anorectal function in the irritable bowel syndrome

BACKGROUND

The pathophysiologic significance of altered intestinal motility and perception in irritable bowel syndrome (IBS) is unclear, as a consistent association with abdominal symptoms has not been proved. Our aim was to investigate the association between abdominal symptoms and anorectal function in IBS.

METHODS

Fifty-two patients recorded their symptoms daily for I week. At the end of the week anorectal function was investigated by manovolumetry before and after a standardized fatty meal. Cluster analysis of daily recorded symptoms and both pre- and postprandial manovolumetric data was performed to identify symptom and physiologic subgroups.

RESULTS

Symptom subgroups did not differ with regard to anorectal function. Physiologic subgroups did not differ with regard to daily recorded symptoms. Postprandially, the thresholds eliciting maximal tolerable distention were decreased in 22 of the patients. This increase in rectal sensitivity was not related to symptoms and may have been caused by the preprandial anorectal measurement, since thresholds for maximal tolerable distention decreased significantly in nine patients retested without an intervening meal.

CONCLUSIONS

Abdominal symptoms and anorectal function are not related in IBS.

Contractile patterns in patients with severe chronic dyspepsia

OBJECTIVE

Antroduodenojejunal interdigestive and postprandial pressure recordings were analyzed in 41 consecutive patients referred for evaluation of severe chronic dyspepsia. In addition to traditional manometric evaluation we also focused on the propagation pattern of individual pressure waves in the proximal duodenum.

METHODS

Catheters with closely spaced side holes for temporospatial analysis of the computerized recordings were used. The dominating symptoms were unexplained nausea and vomiting (n = 18), chronic abdominal pain (n = 16), or both (n = 7). The patients' mean age was 45 yr (31 women and 10 men). Gastric surgery had been performed on 11 patients. Results from 20 healthy volunteers served as a reference range.

RESULTS

Findings were suggestive of neuropathy in 16 (39%) and myopathy in 1 (2.4%) using conventional criteria. Another 19 patients of the 24 with normal condensed recordings showed abnormalities in the propagation pattern of individual pressure waves in phase II and/or during the fed state, when compared with the controls. Absence of phase III of the migrating motor complex was found in 12 patients during the 5-h fasting recording, compared with none in the controls (p < 0.01). Retroperistalsis at the end of phase III in the duodenum was present in at least one of the activity fronts in all patients having migrating motor complex except one, which was similar to the controls. During phase II, unpropagated bursts of phasic and tonic activity were more frequent in patients than in controls (mean 13.2% vs 3.7% of the time; p < 0.05), and a higher proportion of individual contractions was retrograde in patients than in controls (17.4% vs 5% of propagated contractions; p < 0.05). Patients had higher postprandial motility index in the distal duodenum than did controls (p < 0.05). Moreover, after feeding more individual contractions were retrograde in patients than in controls (33.1% vs 10% of propagated contractions; p < 0.01). Sequences of localized supratachyarrythmia, 25-35/min in the antrum and 50-60/min in the small bowel associated with symptoms, were observed in two patients.

CONCLUSION

Manometry is important for demonstration of pathophysiology in patients with unexplained abdominal pain, nausea, and vomiting. Simultaneous analysis of the propagation of individual contractions of interdigestive and fed motility is superior to conventional manometry alone.

Physiological modulation of jejunal sensitivity in health and in irritable bowel syndrome

OBJECTIVES

In irritable bowel syndrome (IBS), enhanced sensitivity to distention of the small bowel has been demonstrated. We sought to compare, in healthy subjects and in IBS patients, the effects on jejunal sensitivity and compliance of feeding, nonperceived rectal mechanoreceptor stimulation, and the above two stimuli in combination.

METHODS

Eleven female IBS patients (49 +/- 13 yr)--six with predominant constipation (IBS-C), and five with predominant diarrhea (IBS-D)--and seven healthy female controls (39 +/- 13 yr) participated. Jejunal distention was applied during fasting, 30 min after a 400-kcal meal, and also during simultaneous nonperceived rectal stimulation.

RESULTS

Jejunal sensitivity was increased after feeding in IBS patients (p = 0.004), specifically in IBS-C patients (p = 0.0001) and in controls (p = 0.02), and was reduced during rectal stimulation in IBS patients (p = 0.0001)--both in IBS-D (p = 0.0001) and in IBS-C (p = 0.03) patients--but not significantly so in controls (p = 0.06). Jejunal sensitivity remained unaltered in both IBS patients and controls during concurrent feeding and rectal stimulation.

CONCLUSIONS

Physiological stimuli in different parts of the gut modify the intensity of jejunal perception, and the interaction of such stimuli further modifies enteric sensitivity. Nonperceived rectal stimulation appears to modify the intensity of jejunal perception to a greater extent in IBS than in health.

Fructose-sorbitol malabsorption and symptom provocation in irritable bowel syndrome: relationship to enteric hypersensitivity and dysmotility

BACKGROUND

Fructose-sorbitol (F-S) mixtures can provoke symptoms in irritable bowel syndrome (IBS) patients, and a proportion of IBS patients also have enteric hypersensitivity to distension. We hypothesized, therefore, that sugar malabsorption and fermentation to produce hydrogen gas may provoke symptoms to a greater extent in IBS patients hypersensitive to distension than in those patients without such hypersensitivity. Our aims were therefore to compare, in IBS patients, symptoms and breath hydrogen responses after F-S, on the basis of jejunal sensitivity and jejunal motor function.

METHODS

Fifteen female IBS patients (44 +/- 15 years) underwent, on separate occasions, 3-h breath hydrogen analyses after ingesting 10 g lactulose and 25 g fructose with 5 g sorbitol. Jejunal sensitivity and motor function were determined by balloon distension and 24-h manometry studies, respectively. Cumulative symptom scores and breath hydrogen production were analysed on the basis of the presence or absence of jejunal hypersensitivity and dysmotility.

RESULTS

Four and seven patients had jejunal hypersensitivity for initial perception and pain, respectively. Eleven, nine, and nine patients had jejunal dysmotility for fasting phase 3, phase 2, and fed motor activity, respectively. Of the patients with symptom provocation after F-S (n = 8 within 3 h, n = 12 within 12 h) or with F-S malabsorption (n = 10), the relative proportion did not differ on the basis of the presence or absence of jejunal hypersensitivity or of motor dysfunction. Symptom scores and hydrogen production also were not different in these subgroups.

CONCLUSIONS

Although carbohydrate malabsorption can provoke symptoms in some IBS patients, there is no consistent association between such a phenomenon and the presence of either jejunal hypersensitivity or dysmotility.

Mast cells: a possible link between psychological stress, enteric infection, food allergy and gut hypersensitivity in the irritable bowel syndrome

Intestinal mast cell activation (degranulation), which results from previous enteric infection and/or intestinal allergy, may play a central role in the gut hypersensitivity in both motor response and visceral perception in the Irritable Bowel syndrome. This occurs through various mediators acting on enteric neurons and smooth muscle cells. Psychological stress may trigger this sensitive alarm system via the brain-gut axis.

Is functional dyspepsia just a subset of the irritable bowel syndrome?

To determine whether functional dyspepsia and irritable bowel syndrome are different entities, epidemiological data, factor analysis studies, physiological data and associated psychological symptoms were reviewed. Between 30% and 60% of patients with either diagnosis also meet the criteria for the other diagnosis, a level greater than expected to occur by chance but not sufficient to infer an identity. Most factor analysis studies identify independent clusters of symptoms corresponding to functional dyspepsia and irritable bowel syndrome. Visceral hypersensitivity is seen throughout the gastrointestinal tract in both disorders, but the motility patterns seen in association with functional dyspepsia (principally antral hypomotility and delayed gastric emptying) differ from the motility patterns seen in irritable bowel syndrome. Psychological symptoms are similar in these two disorders but are not believed to be aetiological for either of them. Thus, based on a factor analysis of gastrointestinal symptoms and differences in intestinal motility, functional dyspepsia and irritable bowel syndrome appear to be different entities.

Evidence of a genetic contribution to functional bowel disorder

OBJECTIVE

Anecdotally, functional bowel disorders (FBD) such as the irritable bowel syndrome appears to cluster in some families, but no studies have investigated the heritability of FBD. We aimed to investigate the influence of heritable factors in FBD.

METHODS

Same sex twin pairs enrolled in the Australian Twin Registry completed a structured interview that included questions related to symptoms consistent with FBD: abdominal pain, diarrhea, constipation, excessive gas or bloating, and nausea. Reasons for the occurrence of each symptom, including their physicians' diagnoses, were recorded. Lisrel 7.16 software was used to fit genetic models following standard procedures.

RESULTS

Of the 686 individual twins from same-sex pairs, 33 (4.8%) had one or more symptoms diagnosed by a medical practitioner as functional bowel disorder. Complete data on this symptom scale was available for 186 monozygotic and 157 same sex dizygotic twin pairs. A model in which 56.9% (95% CI: 40.6-75.9%) of the variance was attributed to additive genetic variance, with the remaining 43.1% attributed to the individual's unique environment, closely fitted the data (chi2=0.01, df=4, p=1.0).

CONCLUSION

Our results suggest that a substantial proportion of the liability for FBD may be under genetic control. Whether this liability is related to the disorder itself or to other potential predisposing factors requires clarification.

Discrimination of irritable bowel syndrome by non-linear analysis of 24-h jejunal motility

Conventional analysis of ambulatory longterm manometry of the small intestine has revealed abnormalities in patients with the irritable bowel syndrome (IBS). The aim was to use methods from non-linear dynamics, in particular the concepts of symbolic dynamics and entropy, in order to discriminate motility in IBS from healthy subjects. 24-h jejunal motility was recorded in 30 IBS patients and 30 healthy subjects. Computerized analysis of contraction amplitudes and intercontractile intervals was performed. Both time series were analysed by symbolic dynamics and entropy to quantify the degree of randomness inherent in the signal. During phase II IBS patients exhibited significantly increased entropies for the intercontractile intervals (IBS: 0.978 +/- 0.016, C: 0.965 +/- 0.020, P = 0.004) and for the contraction amplitudes (IBS: 0.978 +/- 0.008, C: 0.970 +/- 0.026, P = 0.05) compared with healthy subjects. In addition, a significantly increased mean contraction amplitude (mmHg) was found in patients (IBS: 25.2 +/- 4.8, C: 22.2 +/- 3.1, P = 0.003). Considering a combination of both parameters, a diagnostic accuracy of 82% was achieved. We conclude that phase II motility of the small intestine is more random in IBS than in health. Symbolic dynamics seems to be a promising new concept for the analysis of long-term gastrointestinal motility recordings.

Effects of cisapride on symptoms and postcibal small-bowel motor function in patients with irritable bowel syndrome

BACKGROUND

Irritable bowel syndrome is a common cause of abdominal pain and discomfort and may be related to disordered gastrointestinal motility. Our aim was to assess the effects of long-term treatment with a prokinetic agent, cisapride, on postprandial jejunal motility and symptoms in the irritable bowel syndrome (IBS).

METHODS

Thirty-eight patients with IBS (constipation-predominant, n = 17; diarrhoea-predominant, n = 21) underwent 24-h ambulatory jejunal manometry before and after 12 week's treatment [cisapride, 5 mg three times daily (n = 19) or placebo (n = 19)].

RESULTS

In diarrhoea-predominant patients significant differences in contraction characteristics were observed between the cisapride and placebo groups. In cisapride-treated diarrhoea-predominant patients the mean contraction amplitude was higher (29.3 +/- 3.2 versus 24.9 +/- 2.6 mm Hg, cisapride versus placebo (P < 0.001); pretreatment, 25.7 +/- 6.0 mm Hg), the mean contraction duration longer (3.4 +/- 0.2 versus 3.0 +/- 0.2 sec, cisapride versus placebo (P < 0.001); pretreatment, 3.1 +/- 0.5 sec), and the mean contraction frequency lower (2.0 +/- 0.2 versus 2.5 +/- 0.4 cont./min, cisapride versus placebo (P < 0.001); pretreatment, 2.5 +/- 1.1 cont./min] than patients treated with placebo. No significant differences in jejunal motility were found in the constipation-predominant IBS group. Symptoms were assessed by using a visual analogue scale before and after treatment. Symptom scores relating to the severity of constipation were lower in cisapride-treated constipation-predominant IBS patients [score, 54 +/- 5 versus 67 +/- 14 mm, cisapride versus placebo (P < 0.05); pretreatment, 62 +/- 19 mm]. Diarrhoea-predominant IBS patients had a higher pain score after cisapride therapy [score, 55 +/- 15 versus 34 +/- 12 mm, cisapride versus placebo (P < 0.05); pretreatment, 67 +/- 19 mm].

CONCLUSION

Cisapride affects jejunal contraction characteristics and some symptoms in IBS.

Gastrin, cholecystokinin, and somatostatin in a laboratory experiment of patients with functional dyspepsia

OBJECTIVE

To explore the pattern of gastrointestinal hormonal variations in plasma and to relate this to possible pathophysiological mechanisms in functional dyspepsia.

METHOD

There were 25 patients, 12 men and 13 women, aged 24 to 50 years, with recurrent functional dyspepsia, compared with community control subjects pair-wise, matched for age and sex. The subjects participated in a laboratory stress experiment with timed provocations. At fixed intervals, 22 samples of blood were drawn from each subject and frozen for later peptide analyses. Levels of gastrin, cholecystokinin (CCK), and somatostatin were measured by radioimmunoassay. Peptide levels were studied during a friendly greeting, a stress interview, and a food stimulation.

RESULTS

Mean hormone values did not differ between the groups. Smokers had lower mean CCK than nonsmokers. Patients with a high degree of dyspeptic symptoms during the week preceding the experiment had a higher mean somatostatin level than patients with a low degree of dyspeptic symptoms. Heartburn correlated positively with the mean somatostatin level. Mean gastrin correlated with body mass index. During the 15-minute stress interview, significant changes in peptide variations were noted: Gastrin increased in both patient and control group subjects. CCK levels increased in patients from 7.2 pmol/l (6.0-8.5) to 9.8 pmol/l (8.2-11.4), but not in control subjects (p < 0.04, two-way interaction). Somatostatin increased significantly earlier in patients than in the control subjects during the stress interview.

CONCLUSIONS

A positive relationship was found between the mean level of somatostatin and the degree of dyspeptic symptoms. Gastrin, CCK, and somatostatin were all sensitive to an anxiety-provoking interview. CCK and somatostatin may possibly link psychological reactions to the pathophysiology of functional dyspepsia.

Antroduodenal manometry findings in patients with slow-transit constipation

BACKGROUND

The results of subtotal colectomy for slow-transit constipation are unpredictable. Abdominal pain, distension, and bloating often persist after operation. To ascertain whether patients with slow-transit constipation may have a generalized intestinal motor disorder, we studied the antroduodenal motor activity in 20 consecutive patients with slow-transit constipation.

METHODS

All patients underwent symptom registration, whole-gut transit time, anorectal manometry, electromyography of the anal sphincter, the balloon expulsion test, and defecography to characterize their constipation. The motor activity of the the gastric antrum and the proximal small bowel was monitored for 5 h, using a pneumohydraulic water-perfused manometry system with six channels.

RESULTS

Twelve patients (60%) had abnormal patterns of motor activity: abnormal propagation or configuration of phase III in 9 of 12 patients, bursts of non-propagated phasic activity in 8 of 12 patients, and sustained periods of intense phasic activity in 3 of 12 patients. One patient had generalized hypomotility with low-amplitude contractions. In addition, an abundance of so-called discrete clustered contractions was found in 6 of 20 patients.

CONCLUSION

A significant proportion of patients with slow-transit constipation have manometric findings that indicate a generalized motor disorder of the gut. The clinical significance of this finding is still unclear.

Gastrointestinal motility disorders in patients with inactive Crohn's disease

BACKGROUND

Although some symptoms of Crohn's disease may be related to gastrointestinal motility disorders, studies on gastrointestinal motility in inactive Crohn's disease are lacking.

METHODS

Fasting and postprandial motor activity (1 h) was recorded in the gastric antrum and upper small intestine of 35 patients with inactive Crohn's disease and 18 controls, using conventional manometry.

RESULTS

Motor disorders were observed in 26 of 35 patients. The number of phase-II contractions was reduced (1.3 +/- 0.7/min versus 1.8 +/- 0.6/min in controls; P < 0.02) (mean +/- standard deviation), whereas the incidence of propagated single (2.2 +/- 3.2/h versus 0.5 +/- 0.6/h; P < 0.03) and clustered contractions (3.8 +/- 7/h versus 1.1 +/- 1.4, P < 0.04) was markedly increased. Motor abnormalities were more frequent and severe in patients with Crohn's ileitis than in controls, and in patients with gastrointestinal symptoms than in asymptomatic patients.

CONCLUSION

Most patients with inactive, uncomplicated Crohn's disease show marked gastrointestinal motor disorders, characterized either by reduced incidence of small-bowel contractions and increased incidence of single or clustered propagated contractions.

Gastroparesis and small bowel dysmotility in irritable bowel syndrome

Alterations in both gastric emptying (GE) and small bowel motility have been reported in irritable bowel syndrome (IBS); the relationship, however, between these different measures of upper gut motor function in IBS has not been assessed. The aims of this study were therefore: (1) to compare the prevalence and characteristics of altered small bowel motility in IBS patients with and without delayed GE; and (2) to assess the interrelationships between fasting and postprandial small bowel motility in IBS, accounting for delayed GE. Forty-four IBS patients and 25 healthy controls underwent 24 hr ambulant recording of interdigestive and digestive small bowel motility. On a separate occasion the IBS patients had GE of both solids and liquids measured by a dual-isotope scintigraphic technique. Thirty-nine percent of IBS patients had delayed GE. Patients with normal GE had no interdigestive small bowel abnormalities. However, in patients with delayed GE fasting phase II burst frequency was higher than in controls [median 0.21/hr (IQR 0.15-0.34) vs 0.06/hr (0-0,16), P = 0.004]. Postprandially, abnormal phase III-like activity was higher in diarrhea-predominant IBS patients (0-0.08/hr vs 0/hr, P = 0.01), than in patients with normal GE or controls. Furthermore, IBS patients with delayed GE did not have the normal correlation between fasting and postprandial motor parameters (percentage occurrence of clustered contractions, postprandial pattern duration vs preceding MMC cycle length). In conclusion, small bowel motor dysfunction occurs more frequently in IBS patients with concomitant gastroparesis than in patients with normal GE. These findings provide further evidence that a neuropathic process may contribute to the pathogenesis of IBS in a subgroup of IBS patients.

Sigmoid afferent mechanisms in patients with irritable bowel syndrome

Up to 60% of patients with IBS have lowered perception thresholds in the rectum to balloon distension. The current study sought to test the hypothesis that IBS patients with normal perception thresholds in the rectum show hypersensitivity of afferent pathways in the sigmoid colon. Eleven healthy normal subjects and eight IBS patients with normal rectal perception thresholds underwent a balloon distension protocol in the sigmoid and rectum. Discomfort thresholds, receptive relaxation, compliance, and referral patterns were measured. Although IBS patients had significantly lower discomfort thresholds in the sigmoid when measured as volume, pressure, and wall tension, thresholds were similar to normals. Receptive relaxation and dynamic compliance were significantly decreased in IBS patients in the sigmoid. Referral patterns were similar during sigmoid distention in IBS patients in comparison to normals. Despite normal perception thresholds in rectum and sigmoid, IBS patients show evidence for alterations in rectosigmoid afferent mechanisms. In the sigmoid, this is seen in the form of reduced reflex relaxation and compliance and in the rectum in the form of altered viscerosomatic referral.

Muscarinic analgesics with potent and selective effects on the gastrointestinal tract: potential application for the treatment of irritable bowel syndrome

Irritable bowel syndrome (IBS) is a pathopysiolocal condition characterized by abnormal bowel habits that are frequently accompanied by abdominal pain. Current therapy based on reducing high-amplitude GI contractions with nonselective muscarinic antagonists is limited in efficacy due to typical muscarinic side effects and provides no pain relief. We have previously found potent antinociceptive agents acting through muscarinic receptors. In the present work, new 1,2,5-thiadiazole-based structures with muscarinic activity have been evaluated both for activity as analgesics in the mouse withing assay and for activity in normalizing spontaneous cluster contractions in ferret jejunum as a model of IBS in humans. (5R,6R)-exo-6-[4-[(4,4,4-Trifluorobutyl)thio]-1,2,5-thiadiazol+ ++-3-yl] -1-azabicyclo[3.2.1]octane (35, LY316108/NNC11-2192) was found to offer an exceptional profile combining analgesic potency in mouse writhing (ED50 = 0.1 mg/kg) along with potency for normalization of GI motility (ED50 = 0.17 mg/kg). This combination of GI and analgesic potency suggests 35 as an excellent candidate for evaluation as a potential treatment of IBS.

Large-scale ambulatory study of postprandial jejunal motility in irritable bowel syndrome

BACKGROUND

The relationship of small-bowel dysmotility to dietary intake in irritable bowel syndrome (IBS) is obscure.

METHODS

This study evaluated postprandial jejunal motility in IBS patients classified as constipation-predominant (n = 25) or diarrhoea-predominant (n = 35) and compared results against 18 volunteers. Twenty-four-hour ambulatory jejunal manometry was carried out in all subjects, and recordings were analysed by microcomputer and visual assessment.

RESULTS

By means of analysis of variance (fitting factors for channels, meals, and time periods) postprandial contraction frequency was greater in both patient groups compared with normal (constipation-predominant versus normal, diarrhoea-predominant versus normal; P < 0.001). In the constipation-predominant cohort, contraction amplitudes were lower (constipation-predominant versus normal; P < 0.002). Discrete cluster contractions occurred with similar frequency and duration in both patient and volunteer groups.

CONCLUSIONS

Quantitative differences of postprandial jejunal contraction characteristics have been shown between patients with IBS and healthy volunteers. Contraction frequency is greater than normal in both diarrhoea- and constipation-predominant categories, whereas contraction amplitudes are lower in constipation-predominant patients.

Disturbed motilin and cholecystokinin release in the irritable bowel syndrome

BACKGROUND

The irritable bowel syndrome (IBS) is associated with motor abnormalities in the small intestine and colon. Neuropeptides may have an important role in initiating and regulating the intestinal motility. Motilin has been proposed to initiate the peristaltic reflex in the small intestine and cholecystokinin the gastrocolic reflex.

METHODS

In 18 patients with IBS and 11 healthy control subjects plasma motilin and cholecystokinin (CCK) concentrations were measured after intraluminal stimulation of water and a fat-rich meal.

RESULTS

The IBS patients had reduced motilin secretion after both water intake and the fat meal. In contrast, the fat meal elicited an exaggerated and prolonged CCK release in the IBS patients.

CONCLUSIONS

Disturbed motilin and CCK release may partly be responsible for the intestinal dysmotility in the IBS patients.

Newer aspects of the irritable bowel syndrome

IBS is a challenging, functional GI disorder that affects many individuals around the world. Early life experiences, the biologic nature of the condition, and the psychosocial milieu interact to affect the severity and outcome of symptoms. Most people do not seek medical attention for their GI symptoms, or they require intermittent, limited medical therapy and assurance from their physician. Fewer patients, but still a significant number, demand frequent interaction with their physician, who may select pharmacotherapy or psychological and behavioral treatments to control symptoms, depending on the severity. A biopsychosocial approach with attention to the patient-doctor relationship is recommended as the basis for treatment.

Ambulatory 24-hour jejunal motility in diarrhea-predominant irritable bowel syndrome

BACKGROUND

Whether small-bowel motility is abnormal in the irritable bowel syndrome (IBS) is a controversy at present. The aim of our study was to compare ambulatory long-term jejunal motility in 35 IBS patients with predominant diarrhea to normal values obtained in 50 healthy controls.

METHODS

Twenty-four-hour motility was recorded in the proximal jejunum with a portable datalogger and tube-mounted miniature pressure sensors. Fasting motility in the waking (W) and sleeping (S) state and the motor response to a standardized evening meal of 600 kcal underwent visual and computer-aided analysis.

RESULTS

Fasting motility in patients showed migrating motor complex (MMC) cycles of normal length and composition. Uninterrupted runs of discrete clustered contractions during phase II (W) occurred in 57% of patients and 52% of controls but had a significantly longer duration in patients (33 +/- 5 versus 19 +/- 7 min; p < 0.005). During phase II (W) IBS patients had an increase in aborally propagated contractions (41 +/- 2% versus 35 +/- 2%; p < 0.01) and higher contraction amplitudes (26.3 +/- 0.8 versus 23.0 +/- 0.5 mm Hg; p < 0.01). Similar differences were obtained during postprandial motility (47 +/- 3% versus 39 +/- 3%; p < 0.01, and 25.9 +/- 0.9 versus 23.8 +/- 0.05 mm Hg; p < 0.02). In three patients (8.6%) disturbed aboral migration of phase III and irregular burst activity, manometric features of chronic idiopathic intestinal pseudo-obstruction, were identified. Whereas 57% of patients had an entirely normal 24-h manometry, 43% had at least one finding not present in any healthy control.

CONCLUSION

Small-intestinal motility is frequently but not universally abnormal in diarrhea-predominant IBS. The abnormal manometric findings are heterogeneous and range from subtle quantitative changes to severe qualitative abnormalities resembling chronic idiopathic intestinal pseudo-obstruction in a small subset of patients.

Surgery for constipation: a review

PURPOSE

Constipation is related to intestinal motility disorders (colonic inertia (CI)), pelvic floor disturbances (pelvic outlet obstruction), or a combination of both problems. This review summarizes the physiologic and pathophysiologic changes in patients with intractable constipation and gives an overview of surgical treatment options.

RESULTS

Although subtotal colectomy with ileorectal anastomosis is the best surgery for CI, there are still approximately 10 percent of patients who will complain of pain and constipation. A completion proctectomy and an ileoanal pouch procedure may be a viable option in a highly select group of patients. In patients with megabowel, reported results are mixed. Subtotal colectomy, partial colectomy for megacolon, and the Duhamel procedure for megarectum have all been reported with variable results. In patients with an isolated distended sigmoid colon, sigmoid colectomy has achieved good results. Anorectal myectomy has not been proven to be successful in the long term. However, in patients with adult short segment Hirschsprung's disease, myectomy can be successful. Patients with pelvic outlet obstruction can be successfully treated with biofeedback. In a small group of patients with a rectocele or a third degree sigmoidocele, surgical intervention yields a high success rate. Division or resection of the puborectalis muscle is not recommended. In patients with a mixed pattern of CI and pelvic outlet obstruction, surgical intervention alone is often not successful. These patients achieve better results by conservative treatment of pelvic outlet obstruction, followed by a colectomy.

CONCLUSION

Surgical intervention for patients with intractable constipation is rarely necessary. However, thorough preoperative physiologic testing is mandatory for a successful outcome.

Gastric and small intestinal motility in health and disease

Although symptoms possibly related to motor dysfunction appear to be common, primary disorders of the foregut motor apparatus, defined on the basis of a discrete myoneural pathology, are notably rare. This phenomenon may as much reflect the relatively primitive nature of diagnostic methods as the true rarity of such disorders. Although diagnostic methodologies increase in sophistication and availability, their clinical impact has been limited by an imperfect relationship between symptoms and dysfunction and by a relatively poor ability of such tests to predict response to available therapeutic strategies. An ever-increasing understanding of the complex, often interrelated motor and sensory phenomena that contribute to symptoms, together with the development of consensus on the use and interpretation of motility tests and the more widespread application of sophisticated histologic, immunologic, biochemical, and molecular biologic methodologies to the study of these disorders, should lead, in the years to come, to much needed progress in this area.

Psychosocial aspects of functional gastrointestinal disorders

Increased numbers of psychiatric diagnoses and increased levels of psychological distress are seen in the majority of medical clinic patients with gastrointestinal motility disorders. In IBS, psychological symptoms are believed to be comorbid conditions, which do not cause the motility disorder but which do influence the patient's decision to consult a physician. In functional dyspepsia, psychological symptoms are present in many patients, but their role is not known; the available data suggest that psychological symptoms do not predict which patients will consult a physician. Among constipated patients, anxiety is believed to contribute to the development and course of pelvic floor dyssynergia by increasing pelvic floor muscle tension. Constipated patients without physiologic abnormalities to explain their constipation appear to have more psychological symptoms than those with delayed colonic transit, but there is significant psychological distress even in patients with slow transit constipation. Psychological symptoms do not seem to predict which constipated patients will consult a physician. There is an increased incidence of psychiatric diagnoses in patients with esophageal motility disorders as well, but the role that these psychological symptoms play in the course of the disorder is not known. Patients with the most common gastrointestinal motility disorders, IBS and dyspepsia, report experiencing more stressful life events, and IBS patients appear to show a greater increase in gastrointestinal symptoms when exposed to stressors. Laboratory studies document that acute psychological stressors do alter gastric, small bowel, and colonic motility, and patients with IBS appear to show a greater change in colonic and ileal motility with stress than healthy controls. Greater reactivity has not been demonstrated for the esophagus or stomach, however, and it has not been demonstrated for other gastrointestinal motility disorders. A characteristic of many patients who consult gastroenterologists for IBS and other motility disorders is a tendency to report multiple somatic complaints (including many nongastrointestinal complaints) and to overuse medical resources. This pattern of behavior is referred to as somatization or abnormal illness behavior. One source of abnormal illness behavior is childhood social learning, which occurs (1) when parents provide gifts or special privileges to a child who reports somatic symptoms or (2) when parents model abnormal illness behaviors themselves.

Heightened visceral sensation in functional gastrointestinal disease is not site-specific. Evidence for a generalized disorder of gut sensitivity

Alteration in visceral sensation locally at the site of presumed symptom origin in the gastrointestinal tract has been proposed as an important etiopathological mechanism in the so-called functional bowel disorders. Patients presenting with one functional gastrointestinal syndrome, however, frequently have additional symptoms referable to other parts of the gut, suggesting that enhanced visceral nociception may be a panintestinal phenomenon. We measured the sensory thresholds for initial perception (IP), desire to defecate (DD), and urgency (U) in response to rectal balloon distension, and the thresholds for initial perception and for discomfort in response to esophageal balloon distension in 12 patients with irritable bowel syndrome (IBS) and 10 patients with functional dyspepsia (FD), in comparison with healthy controls. As expected, IBS patients exhibited lower rectal sensory thresholds than controls (P < 0.0001), but in addition had significantly lower sensory thresholds for both perception and discomfort evoked by balloon distension of the esophagus (mean +/- SEM: 8.8 +/- 1.3 ml vs 12.1 +/- 1.5 ml (P < 0.05) and 12.2 +/- 1.4 ml vs 16.4 +/- 1.4 ml (P < 0.02) respectively. Patients with FD showed similarly enhanced esophageal sensitivity, with thresholds for perception and discomfort of 8.1 +/- 0.9 ml (P < 0.02), and 10.1 +/- 1.0 ml (p < 0.001), respectively, but were also found to have sensory thresholds for rectal distension similar to those observed in the IBS group, significantly lower than in controls: IP 45.0 +/- 17.6 vs 59.3 +/- 1.5 ml (P < 0.001), DD 98.0 +/- 17.9 vs 298.7 +/- 9.0 ml (P < 0.0001), U 177.2 +/- 25.4 vs 415.1 +/- 12.6 ml (p < 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Altered rectal perception is a biological marker of patients with irritable bowel syndrome

BACKGROUND & AIMS

Lowered visceral perception thresholds have been suggested as a biological marker of irritable bowel syndrome (IBS). The current study sought to determine the prevalence of altered rectal visceral perception in patients with IBS and the correlation of altered perception thresholds with subjective symptoms.

METHODS

Anorectal manometry and rectal perception thresholds to balloon distention were determined in 100 patients with IBS and 15 control subjects. Gastrointestinal and psychological symptoms were assessed by questionnaire. Perception thresholds and symptoms were reassessed after 3 months in 15 patients with IBS.

RESULTS

Ninety-four percent of patients showed altered rectal perception in the form of lowered thresholds for aversive sensations (discomfort), increased intensity of sensations, or altered viscerosomatic referral. Hypersensitivity was found only for aversive sensations in response to rapid phasic distention; stool thresholds and thresholds in response to slow ramp distention were normal. Cluster analysis by physiological parameters identified three IBS subgroups with predominant patterns of symptoms. Longitudinal evaluation indicated a correlation between changes in perception thresholds and symptom severity.

CONCLUSIONS

Because altered rectal perception is present in almost all patients with IBS and perception thresholds correlate with temporal changes in retrospective symptom severity, altered rectal perception represents a reliable biological marker of IBS.

Response to intraluminal gas in irritable bowel syndrome. Motility versus perception

Our aim was to evaluate the response to intraluminal gas in irritable bowel syndrome and to determine whether this response was consequent upon disordered motility or altered perception. We evaluated 10 patients who satisfied the clinical criteria for the diagnosis of irritable bowel syndrome and 10 healthy controls. An eight-lumen perfused catheter assembly was positioned to monitor motor activity in the duodenum and proximal jejunum; a separate side port in the distal duodenum permitted gas infusion. Subjects recorded symptoms of abdominal pain, bloating, and nausea throughout the study, using a visual analog scale. Following an overnight fast and a 60-min basal recording period in the fasted state, subjects ate a standard meal; 60 min later, "sham" gas was administered for 20 min, followed by the actual infusion of nitrogen gas at 40 ml/min. Subjects were randomized to receive atropine (7 micrograms/kg) or placebo intravenously during the period of actual gas infusion. Patients with irritable bowel syndrome described more pain (score, mean +/- SE, control versus irritable bowel: 0.22 +/- 0.16 vs 1.65 +/- 0.5, P < 0.01) and nausea (0.25 +/- 0.21 vs 1.45 +/- 0.64, P < 0.04) during sham gas; motility indices were similar in both groups. During active gas, irritable bowel syndrome patients reported more pain (0.40 +/- 0.39 vs 2.94 +/- 1.16, P < 0.03); motility indices at all sites were similar in both groups. Symptom severity in irritable bowel syndrome subjects randomized to receive atropine was similar to control subjects during active gas infusion; motility indices were similar.(ABSTRACT TRUNCATED AT 250 WORDS)

Oral cromolyn sodium in comparison with elimination diet in the irritable bowel syndrome, diarrheic type. Multicenter study of 428 patients

BACKGROUND

In a significant number of patients affected by the irritable bowel syndrome, an adverse reaction to food is proposed to be a causative factor. A diet that eliminates the offending foods is the obvious treatment for such adverse reactions. Compliance with a dietetic regimen is often poor and sometimes not completely free from risks.

METHODS

Since the diarrheic type of irritable bowel syndrome seems mainly affected by food intolerance, and previous observations suggested that oral cromolyn sodium is effective in such patients, a multicenter therapeutic trial in the diarrheic type of irritable bowel syndrome was carried out in 346 of 409 patients with this disease, to evaluate the effects of oral cromolyn sodium and compare its efficacy with that of an elimination diet.

RESULTS

Symptoms related to the irritable bowel syndrome improved in 60% of patients treated with elimination diet and in 67% of those treated with oral cromolyn sodium (1500 mg/day) for 1 month. Moreover, in both groups clinical results were significantly better in the patients positive to the skin prick test than in the negative ones.

CONCLUSIONS

These results confirm the high prevalence of adverse reactions to foods in diarrheic irritable bowel syndrome and the usefulness of cromolyn sodium treatment in these patients.

Abnormal sphincter of Oddi response to cholecystokinin in postcholecystectomy syndrome patients with irritable bowel syndrome. The irritable sphincter

Standard biliary manometry, including cholecystokinin (CCK) provocation, was performed on 42 consecutive patients (36 F, 6 M, median age 45 years) with postcholecystectomy syndrome (PCS) who had no evidence of organic disease but who had objective clinical features suggesting sphincter of Oddi dysfunction (SOD) (classes I and II). Patients were subdivided into those with (N = 14) and without (N = 28) irritable bowel syndrome (IBS) using a validated symptom questionnaire based on the modified Rome criteria. Resting sphincter of Oddi (SO) motor parameters (basal pressure, contractile amplitude and frequency, and proportion of retrograde contractions), the presence of abnormal manometry, and the presence of an abnormal response to CCK were compared in the two groups. No significant differences in resting parameters of SO motor activity between patients with and without IBS were observed, and abnormal biliary manometry as a whole was not more prevalent in either group (8/13 and 18/27, respectively). An abnormal response to CCK (failure of complete inhibition of phasic contractions), however, was demonstrated in five of 12 patients with IBS compared with only one of 23 patients without IBS (P = 0.01). In patients with postcholecystectomy SOD, an abnormal response of the SO to CCK thus appears to be an important feature of the subset of patients with concomitant IBS.

Scintigraphic measurement of ileocaecal transit in irritable bowel syndrome and chronic idiopathic constipation

This study investigated the hypothesis that some features of functional gastrointestinal disorders may be associated with abnormalities of ileocaecal transit by measuring ileocaecal transit using a scintigraphic technique in 43 patients with chronic constipation, 20 patients with irritable bowel syndrome (IBS), and 18 control subjects. Subjects ingested enteric coated capsules, which delivered 111-indium radionuclide to the distal ileum. Gammacamera images were acquired at hourly intervals until caecal filling was complete. Ileocaecal transit was defined as the time between peak scintigraphic activity in the terminal ileum and peak activity in the caecum. The mean (SD) ileocaecal transit of 103 (50) minutes in patients with IBS was significantly faster than that in control subjects (mean (SD) ileocaecal transit 174 (78) minutes, p < 0.002). There were no significant differences in ileocaecal transit between patients with chronic idiopathic constipation and the control subjects, or between patients with constipation predominant and diarrhoea predominant IBS. This study developed a practical scintigraphic method of measuring ileocaecal transit. The rapid ileocaecal transit in both the constipation and diarrhoea predominant forms of IBS suggests that bloating may not after all result from delayed ileal emptying.

Review article: the hypersensitive gut--peripheral kappa agonists as a new pharmacological approach

Hypersensitivity to pain is a common component of functional bowel disorders. Hyperalgesia may be induced by various stimuli which produce a cocktail of inflammatory mediators that decrease the pain threshold. Drugs able to block these peripheral events within the gut may offer a new pharmacological approach for treating functional bowel disorders. Kappa opioids have been shown to inhibit somatic pain through a peripheral mechanism of action, acting directly on receptors located on peripheral sensory endings. They can block both the nociceptive messages as well as the release of sensory peptides. This paper reviews the effects of opioid agonists on gut visceral pain and motility anomalies induced by visceral pain. Kappa opioids have strong effects on all models tested, with a peripheral mechanism of action allowing the design of drugs acting only in the periphery and having no central nervous system side-effects. This contrasts with mu agonists which are centrally active on pain and worsen the subsequent transit and motility anomalies.

Irritable bowel syndrome. Managing the patient with abdominal pain and altered bowel habits

Irritable bowel syndrome is a common complex of syndromes thought to be generated by a motility or sensory disturbance of the gastrointestinal tract. It is a frequent cause of chronic abdominal pain and altered bowel habits. Patients who seek medical attention for irritable bowel syndrome often do so because of psychosocial factors. Therapy remains largely empirical, directed toward the relief of symptoms in the context of a supportive physician-patient relationship.

Evidence for the hypersensitivity of lumbar splanchnic afferents in irritable bowel syndrome

BACKGROUND/AIMS

The pathways underlying rectal hypersensitivity to balloon distention in patients with irritable bowel syndrome (IBS) are not known. The aim of this study was to characterize the involvement of sacral and thoracolumbar afferents in the perception of rectal distention.

METHODS

Rectal balloon distention was performed in 15 normal control subjects, 6 patients with spinal cord injury, and 50 patients with IBS using a slow-volume ramp (40 mL/min) or rapid phasic step distension. Additional studies were performed in the presence of 2% intrarectal lidocaine.

RESULTS

Patients with spinal cord injury with lesions below T7 reported sensations only during phasic distention. Sixty percent of patients with IBS (n = 50) were hypersensitive for discomfort during phasic distention, whereas only 4% were hypersensitive during ramp distention. Less than 15% of patients were hypersensitive for the sensation of stool. In normal patients, lidocaine increased thresholds in response to slow ramp distention by 40%-70% but had no effect on perception in response to other types of distention. Lidocaine had no effect on (1) thresholds in response to either ramp or phasic distention in normosensitive or hypersensitive patients with IBS or (2) the rate of receptive relaxation or rectal compliance in any group.

CONCLUSIONS

Rapid phasic distention preferentially stimulates splanchnic afferents. Hypersensitivity of these afferents in patients with IBS is unaffected by mucosally applied lidocaine.

Abnormal gastrointestinal motility in patients with celiac sprue

No study to date has objectively investigated whether the motor behavior of the small bowel is abnormal in celiac sprue. The purpose of this study was to systematically address this topic by means of intraluminal pressure recordings in a series of such patients. Sixteen subjects (nine adults, seven children, age range 2-69 years) with celiac sprue were recruited and studied while untreated. Manometric examination was carried out for 6 hr during fasting and 3 hr after a meal. Adult celiac patients displayed a significantly (mean +/- SEM) greater frequency of migrating motor complexes in comparison to controls during fasting (4.44 +/- 1.6 vs 2.45 +/- 0.20, P < 0.01), whereas no differences were found in the pediatric group with respect to this variable. Fasting motor abnormalities, chiefly represented by discrete clustered contractions, giant jejunal contractions, and bursts of nonpropagated contractions, were discovered in a high percentage in both groups of celiac subjects (89% in adults and 44% in children, respectively). Similar abnormalities were observed in the postprandial period, especially in adults. In conclusion, patients with celiac sprue frequently display discrete gastrointestinal motor abnormalities, which though perhaps nonspecific may account for several symptoms complained of by such patients.

Basic and clinical aspects of visceral hyperalgesia

Although physiological stimuli in the healthy gastrointestinal tract are generally not associated with conscious perception, chronic abdominal discomfort and pain are the most common symptoms resulting in patient visits with gastroenterologists. Symptoms may be associated with inflammatory conditions of the gut or occur in the form of so-called functional disorders. The majority of patients with functional disorders appear to primarily have inappropriate perception of physiological events and altered reflex responses in different gut regions. Recent breakthroughs in the neurophysiology of somatic and visceral sensation are providing a series of plausible mechanisms to explain the development of chronic hyperalgesia within the human gastrointestinal tract. A central concept to all these mechanisms is the development of hyperexcitability of neurons in the dorsal horn, which can develop either in response to peripheral tissue irritation or in response to descending influences originating in the brainstem. Taking clinical characteristics and the concept of central hyperexcitability into account, a model is proposed by which abdominal pain from chronic inflammatory conditions of the gut and functional bowel disorders such as noncardiac chest pain, nonulcer dyspepsia, and irritable bowel syndrome could develop by multiple mechanisms either alone or in combination.

Effect of cholecystokinin on gastric motility in humans

Gastric emptying after food ingestion is regulated by neural and hormonal factors. However, the relative contributions of each pathway is not yet clearly defined. The classic gut hormone CCK seems to be involved in the regulation of gastric emptying in humans. Experimental evidence is best for gastric emptying of liquid meals that release CCK from the duodenum: (1) CCK infused at postprandial plasma concentrations inhibits gastric emptying of a liquid and a semisolid meal. (2) Administration of the CCK antagonist loxiglumide significantly accelerated gastric emptying of a liquid mixed meal and a glucose meal. Discrepant results with the antagonist MK329 are difficult to explain considering the marked acceleration of gastric emptying rates by the specific and potent antagonist MK329 shown in several animal studies. Taken together, current information favors the conclusion, however, that CCK mainly controls gastric emptying of the liquid but not the solid components. Thus, CCK is involved in the physiologic regulation of gastric emptying and gastric motility in man. Blocking CCK-A receptors accelerates gastric emptying of liquid meals and abolishes the gastrocolonic reflex. Therefore, CCK may play a role as a common regulator of postprandial gallbladder contraction and pancreatic enzyme secretion as well as of gastric emptying rates under certain conditions. Such common control would optimize the nutrient-to-digestive juices concentration ratio. The importance of endogenous CCK on gastric emptying of solid meals, however, is poorly understood and remains to be defined. Only very limited information is available on gastric motility. Much more work has to be done before a clear concept can be developed.