High-resolution anorectal manometry: An expensive hobby or worth every penny?

Introduced approximately 10 years ago, high-resolution manometry catheters have fostered interest in anorectal manometry. This review, which accompanies two articles in this issue of Neurogastroenterology and Motility, reviews the methods, clinical indications, utility, and pitfalls of anorectal manometry and revisits the American Gastroenterological Association (AGA) Medical Position Statement on Anorectal Testing Techniques, which was last published in 1999. High-resolution manometry provides a refined assessment of the anorectal pressure profile, obviates the need for station pull-through maneuvers, and minimizes movement artifacts. In selected cases, this refined assessment may be useful for identifying structural abnormalities or anal weakness. However, many manometry patterns that were previously regarded as abnormal are also observed in a majority of healthy patients, which substantially limits the utility of manometry for identifying defecatory disorders. It is our impression that most conclusions of the AGA medical position statement from 1999 remain valid today. High-resolution techniques have not substantially affected the number of publications on or management of anorectal disorders. The ongoing efforts of an international working group to standardize techniques for anorectal manometry are welcome. Although high-resolution manometry is more than an expensive hobby, improvements in catheter design and further research to rigorously define and evaluate these techniques are necessary to determine if they are worth every penny.

Symptom-association probability between meal ingestion and abdominal pain in patients with irritable bowel syndrome. Does somatization play a role?

BACKGROUND

Patients with irritable bowel syndrome (IBS) complain of postprandial abdominal pain, but it is still unknown how much of this association is due to chance. Somatization enhances the perception of symptoms after a meal. We assessed: (i) the proportion of meal-related pain periods and the symptom-association probability (SAP) between the two variables in IBS patients; and (ii) how this association is affected by somatization.

METHODS

Seventy IBS patients recorded the times of meals and abdominal pain in a 10-day diary card. The proportion of postmeal pain periods was calculated in relation to the total number of 90-min periods with pain. Fisher's exact test was used to calculate the probability (p) of an association within a time window of 90 min, and the SAP was calculated as (1 - p) × 100%. The IBS Symptom Severity Scale, the SCL90-R for psychological symptoms, and the SF-36 for the quality of life were completed.

KEY RESULTS

The proportion of postmeal pain periods was 42 ± 27%. SAP was significant (p < 0.05) in 32 patients (45%). Somatization was altered in 30 patients (47%), who were younger and had more severe IBS and a poorer quality of life. Somatization did not influence the association between meal ingestion and abdominal pain.

CONCLUSIONS & INFERENCES

Meal ingestion and abdominal pain are significantly associated in 45% of IBS patients. Somatization influences IBS severity and the patients' quality of life, but not the strength of the association between eating and pain.

Is the subjective perception of lactose intolerance influenced by the psychological profile?

BACKGROUND

Symptoms of lactose intolerance are often attributed to lactose malabsorption but, as this relationship has not been demonstrated when a small dose of lactose similar to that contained in one cup of milk is ingested by intolerant patients, psychological factors may play a role in altered symptom perception.

AIM

To assess the hypothesis that the psychological profile influences the symptoms of lactose intolerance.

METHODS

One hundred and two consecutive patients underwent a 15 g lactose hydrogen breath test to assess lactose malabsorption. The patients recorded the presence and severity of symptoms of lactose intolerance during the breath test using visual analogue scales. The psychological profile was assessed using a psychological symptom checklist, and health-related quality of life by means of the short-form health survey.

RESULTS

Lactose malabsorption and intolerance were diagnosed in, respectively, 18% and 29% of the patients. The two conditions were not associated, and the severity of intolerance was even less in the patients with malabsorption. Multivariate logistic analysis showed that a high somatisation t-score was significantly associated with lactose intolerance (odds ratio 4.184; 1.704-10.309); the effects of the other psychological variables and of lactose malabsorption were not statistically significant. Health-related quality of life was significantly reduced in the patients with somatisation, but not in those with lactose malabsorption.

CONCLUSIONS

The symptoms of lactose intolerance during hydrogen breath testing at a low physiological lactose load, are unrelated to lactose malabsorption, but may reveal a tendency towards somatisation that could impair the quality of life.

Discrepancy between recalled and recorded bowel habits in irritable bowel syndrome

BACKGROUND

A discrepancy between recalled and recorded bowel habit subtypes has been reported in irritable bowel syndrome (IBS), but the reasons for it remain unclear.

AIM

To assess the agreement between recalled and recorded bowel habit subtypes; to determine whether any discrepancy is related to stool form variability or psychological factors; and to test the correlations of recalled and recorded stool form with colonic transit time.

METHODS

Bowel habit subtype was established in 54 IBS patients at the enrolment visit (recalled) and with the aid of diary cards (recorded). Colonic transit time, the variability of stool form and the patients' psychological profiles were also recorded.

RESULTS

Recalled and recorded bowel habit subtypes agreed in only 54% of the patients (kappa = 0.28). Stool form variability was greater among the patients whose recalled and recorded bowel habit subtypes were discordant (P = 0.03), whereas the psychological profiles were not different. Colonic transit time significantly correlated with stool form only when it was recorded on diary cards.

CONCLUSION

The discrepancy between recalled and recorded bowel habits in IBS patients is related more to stool form variability than an altered psychological profile. Diary cards should be used to ensure that stool form reflects colonic transit time.

Methodology and indications of H2-breath testing in gastrointestinal diseases: the Rome Consensus Conference

BACKGROUND

Breath tests represent a valid and non-invasive diagnostic tool in many gastroenterological conditions. The rationale of hydrogen-breath tests is based on the concept that part of the gas produced by colonic bacterial fermentation diffuses into the blood and is excreted by breath, where it can be quantified easily. There are many differences in the methodology, and the tests are increasingly popular.

AIM

The Rome Consensus Conference was convened to offer recommendations for clinical practice about the indications and methods of H2-breath testing in gastrointestinal diseases.

METHODS

Experts were selected on the basis of a proven knowledge/expertise in H2-breath testing and divided into Working Groups (methodology; sugar malabsorption; small intestine bacterial overgrowth; oro-coecal transit time and other gas-related syndromes). They performed a systematic review of the literature, and then formulated statements on the basis of the scientific evidence, which were debated and voted by a multidisciplinary Jury. Recommendations were then modified on the basis of the decisions of the Jury by the members of the Expert Group.

RESULTS AND CONCLUSIONS

The final statements, graded according to the level of evidence and strength of recommendation, are presented in this document; they identify the indications for the use of H2-breath testing in the clinical practice and methods to be used for performing the tests.

Perceptual sensitivity and response bias during rectal distension in patients with irritable bowel syndrome

Patients with irritable bowel syndrome (IBS) report an increased frequency of sensations during rectal distension in comparison with healthy subjects. This alteration might be due to a psychological response bias leading patients to over report their sensations. The aim of this study was to measure perceptual sensitivity and response bias during rectal distension in healthy subjects and IBS patients using the sensory decision theory (SDT). Thirteen healthy subjects and 22 IBS patients underwent five rectal distensions up to 100 mL, five up to 200 mL and five sham distensions. They were asked to identify the distension by means of an electronic marker. Perceptual sensitivity and response bias were calculated according to the SDT. The patients identified a more 100 mL distensions than the healthy subjects (P = 0.02), whereas there was no difference in the number of identified 200 mL and sham distensions between the two groups. The perceptual sensitivity of IBS patients was significantly greater during 100 mL (P = 0.01), but not during 200 mL distensions. The response bias was not significantly different between the two groups. These data suggest that the increased frequency of sensations reported by IBS patients is not due to a psychological response bias.

Plasma chromogranin A in patients with autoimmune chronic atrophic gastritis, enterochromaffin-like cell lesions and gastric carcinoids

OBJECTIVE

In atrophic body gastritis (ABG) chronic hypergastrinaemia stimulates enterochromaffin-like (ECL) cell proliferation with development of cell hyperplasia, dysplasia and possibly type-1 gastric carcinoids. As circulating chromogranin A (CgA) levels are a marker of neuroendocrine tumours, we evaluated the clinical usefulness of CgA assay in ABG patients to detect those with carcinoids.

DESIGN AND METHODS

Plasma CgA levels were measured using a commercial ELISA in 45 healthy volunteers, nine patients with type-1 gastric carcinoids and 43 consecutive ABG patients (21 without and 22 with ECL cell hyperplasia/dysplasia).

RESULTS

CgA levels were significantly higher in ABG patients with and without gastric carcinoids than in healthy subjects (P < 0.001). The highest values occurred in patients with carcinoids (median (interquartile range): 58.1 (44.5-65.3) U/l) and with ECL cell hyperplasia/dysplasia (35.5 (31.8-48.65) U/l) but there were no significant differences in CgA among the various subgroups of ABG patients classified according to ECL cell status. Nevertheless, in ABG patients without carcinoids CgA values correlated with the presence and severity of ECL cell lesions (r(s) = 0.428, P < 0.01). The sensitivity and specificity of the CgA assay in identifying patients with carcinoids were 100 and 23% respectively.

CONCLUSIONS

CgA plasma levels reflect the histological degree of ECL cell lesions in patients with ABG but the assay specificity is too low to detect among these patients those with gastric carcinoids.

Effect of rectal distension on abdominal girth

It has been postulated that a viscerosomatic reflex activated by gut distension and inhibiting abdominal wall muscle tone may be one of the mechanisms underlying functional abdominal distension. Any demonstration of such a reflex has to take into account the fact that gut distension may increase abdominal girth as a result of volume displacement. As biomechanical and sensory rectal responses vary at different rates of rectal distension, we hypothesized that different rates of rectal distension might reveal different changes in abdominal girth. Abdominal girth was continuously recorded in 14 healthy subjects using a previously validated extensometer. The rectal distensions were made in a randomized order at rates of 100 mL min(-1) or 10 mL min(-1) up to 150 mL, and sham distensions were used as controls. An increase in abdominal girth was observed at the end of both distensions (P </= 0.008): it was greater after the fast (1.1 +/- 0.5 mm) than after the slow distension (0.8 +/- 0.7 mm), but this difference was not statistically significant (P = 0.2). In conclusion, we were unable to demonstrate the existence of a viscerosomatic reflex activated by gut distension under our experimental conditions.

Abdominal distension after colonic lactulose fermentation recorded by a new extensometer

Colonic lactulose fermentation induces bloating, but whether it also causes abdominal distension is not known. The aim of this study was to assess the effect of colonic lactulose fermentation on abdominal girth using a new extensometer. We recorded abdominal girth in 24 healthy subjects by means of an extensometer that measures the phase shift of an ultrasound wave propagating in a tube encircling the abdomen. The recordings were continuously made for 3 h after the ingestion of 100 mL of tap water with (16 subjects) or without (eight subjects) 10 g of lactulose. Every 10 min, H2 in the breath was analysed and the intensity of bloating was recorded. Bloating was never reported after water ingestion, whereas it was reported by 10 subjects after lactulose ingestion (P = 0.002). The mean +/- SD changes in abdominal girth in comparison with resting conditions were statistically significant after lactulose ingestion (3 +/- 2.9 mm; P = 0.002) but not after water ingestion (-0.2 +/- 2.7 mm; P = 0.82). The area under the curve of the changes in abdominal girth after lactulose were significantly greater than after water ingestion (P = 0.03). In conclusion, colonic lactulose fermentation induces bloating and abdominal distension. The new extensometer is useful for continuously recording changes in abdominal girth.

Effect of continuous rectal distention on anal resting pressure

PURPOSE

Intermittent distention of the rectum induces internal anal sphincter relaxation, but whether continuous rectal distention might affect the resting pressure of the anal canal and the frequency of internal anal sphincter relaxations has not yet been investigated. The aim of this study was to record anal pressure under resting conditions and at two levels of continuous rectal distention.

METHODS

Anal pressure was recorded by means of water-perfused catheters under resting conditions and at two levels of rectal distention controlled by an electronic barostat in eight healthy subjects.

RESULTS

Continuous rectal distention did not significantly change mean anal resting pressure, but it did significantly decrease the amplitude of ultraslow waves (from 29 +/- 9 mmHg under resting conditions to 23 +/- 6 and 21 +/- 3 mmHg during lesser and greater rectal distention; P = 0.017 and P = 0.012, respectively) and increase the frequency of internal anal sphincter relaxations (from 1.3 +/- 1.3/hour under resting conditions to 8.8 +/- 4.3/hour and 11.0 +/- 4.8/hour during lesser and greater distention; P = 0.012 in both comparisons).

CONCLUSIONS

The resting pressure of the anal canal is maintained during continuous rectal distention. The decreased amplitude of ultraslow waves and increased frequency of the internal anal sphincter relaxations induced by rectal distention reveal a complex functional relationship between the rectum and the anal canal.

Autonomic control of heart period in duodenal ulcer patients insights from spectral analysis of heart rate variability

Beyond the fundamental pathogenetic importance of Helicobacter Pylori a possible additional role of vagal innervation in favouring or modulating the clinical history of duodenal ulcer (DU) has been suggested by old studies employing invasive methodologies. Aim of this study was to assess whether vagal prevalence in autonomic modulation was present in healed DU patients (n=20) as compared to controls,(n=50), using a validated non-invasive methodology, based on spectral analysis of cardiovascular variability. This approach provides markers of the sympathetic and vagal modulations of the SA node, respectively by way of the normalized low frequency (LF(RR)) and high frequency (HF(RR)) components of RR interval variability; LF/HF ratio furnishes a marker of sympatho-vagal balance. In addition, sham feeding (SF) provided a means to assess, in DU patients, neurally mediated acid secretion, as the SF acid output (SAO) to basal acid output (BAO) ratio (SAO/BAO). Results showed that LF(RR) was smaller in DU patients than in controls (40.3+/-3.9 vs. 52.3+/-2.3 normalized units, nu; P<0.05). On the contrary, HF(RR) was greater (52.1+/-3.7 vs. 35.7+/-2.3 nu; P<0.05). Conversely the LF component of SAP variability, a marker of sympathetic vasomotor modulations, and the index alpha, a measure of baroreflex control of the SA node, as well as respiratory patterns, were similar in the two groups. SAO/BAO ratio was significantly correlated with markers of autonomic control of the SA node (r = -0.67, P<0.0083 with HF(RR)). In conclusion results suggest an enhanced vagal modulation of heart period in DU patients at rest, that appears linked to indices of neurally mediated gastric acid secretion response.

Sensations induced by medium and long chain triglycerides: role of gastric tone and hormones

BACKGROUND

The relative roles of gastric relaxation and the neuroendocrine signals released by the small intestine in the perception of nutrient induced sensations are controversial. The different effects of long chain (LCT) and medium chain (MCT) triglyceride ingestion on perception, gastric relaxation, and hormonal release may help to elucidate the mechanisms underlying nutrient induced sensations.

AIMS

To compare the effects of intraduodenal LCT and MCT infusions on perception, gastric tone, and plasma gut hormone levels in healthy subjects.

SUBJECTS

Nine fasting healthy volunteers.

METHODS

The subjects received duodenal infusions of saline followed by LCTs and MCTs in a randomised order on two different days. The sensations were rated on a visual analogue scale. Gastric tone was measured using a barostat, and plasma gut hormone levels by radioimmunoassay.

RESULTS

LCT infusion increased satiation scores, reduced gastric tone, and increased the levels of plasma cholecystokinin, gastric inhibitory polypeptide, neurotensin, and pancreatic polypeptide. MCT infusion reduced gastric tone but did not significantly affect perception or plasma gut hormone levels. LCTs produced greater gastric relaxation than MCTs.

CONCLUSIONS

The satiation induced by intraduodenal LCT infusion seems to involve changes in gastric tone and plasma gut hormone levels. The gastric relaxation induced by MCT infusion, together with the absence of any significant change in satiation scores and plasma hormone levels, suggests that, at least up to a certain level, gastric relaxation is not sufficient to induce satiation and that nutrient induced gastric relaxation may occur through cholecystokinin independent mechanisms.

Loss of interstitial cells and a fibromuscular layer on the luminal side of the colonic circular muscle presenting as megacolon in an adult patient

BACKGROUND

Animal studies have shown that the neuromuscular structures on the luminal side of the colonic circular muscle coordinate circular muscle activity. These structures have been identified by electron microscopy in the normal human colon, but have never been thoroughly studied in patients with acquired intestinal hypoganglionosis.

AIMS

To perform histological, immunocytochemical, and electron microscopic examinations of the colon of a patient with acquired intestinal hypoganglionosis presenting as megacolon.

PATIENT

A 32 year old man with a one year history of constipation and abdominal distention, a massively dilated ascending and transverse colon, and a normal calibre rectum and descending and sigmoid colon. He had a high titre of circulating serum anti-neuronal nuclear antibodies.

METHODS

Histology, immunocytochemistry (for neurofilaments, neurone specific enolase, synaptophysin, glial fibrillar acidic protein, S100 protein, and smooth muscle alpha-actin), and electron microscopic examinations on the resected colon.

RESULTS

The number of ganglion cells and nerve trunks was decreased throughout the colon. Disruption of the neural network and a loss of interstitial cells of Cajal were observed on the luminal side of the circular muscle; in their place, the non-dilated colon contained a hypertrophic fibromuscular layer.

CONCLUSIONS

Striking architectural alterations occurred at the site regarded as the source of the coordination of colonic circular muscle activity in an adult patient with acquired intestinal hypoganglionosis presenting as megacolon.

Mistaken diagnosis of eosinophilic colitis

A 69-year-old male chronic alcohol abuser suffering from diarrhoea and with a number of discrete pruriginous and erythematous lesions of the trunk was referred to our Unit with a diagnosis of idiopathic eosinophilic colitis in order that we might determine corticosteroid treatment. Diagnosis was based on the presence of marked peripheral eosinophilia and massive eosinophilic infiltration at colonic biopsy, and the exclusion of parasitic infection by means of two different microscopic stool examinations of five samples. However, repeated stool examinations of ten samples collected on separate days and evidence of impaired cell-mediated immunity allowed a definite diagnosis of Strongyloides stercoralis autoinfection or hyperinfection. Due to the poor sensitivity of stool examination in the diagnosis of Strongyloides stercoralis infection, a careful search for this parasite should be made in all patients with comparable clinical findings before formulating a diagnosis of idiopathic eosinophilic colitis, because consequent steroid treatment may have a fatal outcome by inducing widespread dissemination of the parasite.

Local regulation of postprandial motor responses in ileal pouches

BACKGROUND

Local mechanisms are involved in the postprandial regulation of ileal tone in healthy subjects, but whether these mechanisms affect the postprandial tonic response of ileal pouches has not yet been investigated.

AIMS

To study the effect of a meal on pouch tone and phasic motor activity in patients with gut continuity or ileostomy and, in the latter group, the effect of a pouch perfusion with chyme or saline.

PATIENTS

Twenty patients with ileal pouches: 10 with gut continuity and 10 with ileostomy.

METHODS

Pouch tone and the frequency of phasic volume events were recorded with a barostat under fasting and postprandial conditions and after perfusion of the isolated pouch with chyme or saline.

RESULTS

The meal increased pouch tone and the frequency of phasic volume events in the patients with gut continuity, but not in those with ileostomy. Pouch perfusion with chyme induced a greater increase in pouch tone than saline.

CONCLUSIONS

The meal stimulated pouch tone and phasic motor activity. These effects were at least partially related to local pouch stimulation by intraluminal contents.

Intraesophageal pH monitoring during acid infusion in patients with systemic sclerosis

Incidental clinical observations suggest that buffering substances may accumulate in the distal esophagus of patients with systemic sclerosis. The aim of our study was to assess if the buffering capacity of the intraesophageal milieu is increased in patients with systemic sclerosis and if this effect can be correlated to some pathophysiological aspects of the disease. We recorded intraesophageal pH before and during a 10-min intraesophageal infusion of acid (HCl 0.01 N, 1 ml/min), as well as esophageal motility and clearance function, in 16 patients with systemic sclerosis and 10 healthy subjects. Esophageal buffering capacity expressed as the area under the curve of intraesophageal pH during acid infusion was significantly higher in the patients than in the controls, and this variable was directly correlated with esophageal clearing time. In conclusion, esophageal buffering capacity is increased in patients with systemic sclerosis and is possibly the consequence of the accumulation of buffering substances in the distal esophagus.

Postprandial gut peptide plasma levels in women with idiopathic slow-transit constipation

BACKGROUND

As abnormalities of circulating gut regulatory peptides may have pathogenetic relevance in chronic idiopathic slow-transit constipation, we measured fasting and postprandial levels of plasma pancreatic polypeptide, motilin, cholecystokinin, neurotensin, and somatostatin in women with the disease. Results were compared with those of women with normal bowel habits.

METHODS

Eight women with slow-transit constipation and 10 healthy women were studied. Blood samples were taken at regular intervals in fasting conditions and for 3 h after a standard solid-liquid meal (550 kcal). Gut peptide plasma levels were measured with a radioimmunoassay.

RESULTS

Fasting gut peptide levels and postprandial pancreatic polypeptide responses were normal in constipated patients, in whom, however, motilin levels did not increase after the meal, and postprandial concentration-time curves of cholecystokinin, neurotensin, and somatostatin were delayed. Mean +/- standard error of the mean peak times in patients and in controls were, respectively, 99 +/- 14.7 and 46 +/- 4.1 min (P < 0.01, Mann-Whitney test) for cholecystokinin, 135 +/- 9.8 and 60 +/- 3.9 min (P < 0.01) for neurotensin, and 111 +/- 17.7 and 51 +/- 6.0 min (P < 0.05) for somatostatin.

CONCLUSIONS

Patients with slow-transit constipation have abnormal postprandial patterns of motilin, cholecystokinin, neurotensin, and somatostatin.

Plasma somatostatin-like immunoreactivity and somatostatin-28 levels in obese men

Somatostatin (SS) impairs nutrient absorption. It has been suggested that hyposomatostatinaemia may be involved in the pathogenesis of obesity. However, data on postprandial SS-like immunoreactivity (SLI) levels in obese subjects are controversial and the levels of SS-28, the main molecular form of circulating SLI in healthy subjects, have not been determined. To characterise the fasting and postprandial plasma pattern of SLI and SS-28 in obese men, we studied eight obese men (age 24-32 yr, BMI 33-42 kg/m2), with normal glucose tolerance test and normal gastric emptying of solids, and eight healthy men (age 24-39 yr, BMI 21-24 kg/m2). Blood samples were taken at regular intervals in fasting conditions and for 2 h after a standard solid-liquid meal (2.3 MJ). Plasma SLI and SS-28 were measured by RIA. Our results showed that fasting and postprandial plasma SLI and SS-28 levels were not significantly different in healthy and obese subjects. In conclusion SS-28 is the predominant form of circulating SLI in obese subjects. The normal pattern of fasting and postprandial plasma SLI and SS-28 levels in such subjects suggests that somatostatin does not have a pathogenetic role in obesity.

Plasma somatostatin levels in patients with chronic idiopathic intestinal pseudo-obstruction

OBJECTIVES

Somatostatin participates in the control of gut motility. Recently, somatostatin analogs have been proposed as therapeutic agents for chronic intestinal pseudo-obstruction, although the endogenous somatostatin pattern has never been assessed in this syndrome. We aimed to evaluate fasting and postprandial plasma somatostatin levels in patients with chronic idiopathic intestinal pseudo-obstruction (CIIP).

METHODS

We studied eight patients with CIIP and 10 healthy volunteers. Blood samples were taken at regular intervals while patients and subjects fasted and during the 3 h after a standard solid/liquid meal (550 kcal) had been eaten. Somatostatin was measured by radioimmunoassay.

RESULTS

Fasting somatostatin levels were normal, whereas postprandial peptide responses were markedly impaired or even absent in patients with CIIP.

CONCLUSIONS

An impaired postprandial somatostatin response in patients with CIIP seems to be characteristic of this heterogenous disorder. Whether the lack of somatostatin response to a meal identifies patients with severe gut dysmotility for whom treatment with somatostatin analogs would be useful remains to be verified.

Oesophageal manometry in the evaluation of megacolon with onset in adult life

BACKGROUND

Oesophageal motility is often impaired in patients with megaduodenum and other forms of intestinal pseudo-obstruction in which a visceral myopathy or neuropathy may be present. Idiopathic longstanding megacolon with onset in adult life is still a poorly defined entity, which may also be part of a more widespread motility disorder but in which oesophageal motility has not been yet systematically studied.

AIMS

To assess oesophageal motility in patients with longstanding idiopathic megacolon with onset in adult life.

PATIENTS

14 consecutive subjects with idiopathic megacolon whose symptoms began after the age of 10 and a clinical history of 2-22 years.

METHODS

Standard barium enema, water perfused oesophageal manometry, and also anorectal manometry.

RESULTS

Oesophageal motility was impaired in five patients (36%; 95% confidence intervals 16 to 61%). Normal peristalsis was substituted by low amplitude multiple peaked simultaneous contractions in four subjects and by undetectable contractions in one. In three of them the lower oesophageal sphincter did not relax after swallows; in the same patients anal relaxation after rectal distension was also undetectable. All five patients with impaired oesophageal motility had a colonic dilatation sparing the rectum. Three of them reported constipation and a history of pesudo-obstruction and the other two only abdominal distension.

CONCLUSIONS

Oesophageal manometry should be performed in patients with longstanding idiopathic megacolon with onset in adult life, in particular if the rectum is not dilated and even in absence of pseudo-obstruction. This simple test may disclose a more widespread visceral neuropathy or myopathy. Such a diagnosis helps to better understand the cause of the colonic dilatation and may be clinically relevant for treatment of the patients.

Hereditary megaduodenum

Hereditary megaduodenum is a rare disease with autosomal dominant transmission characterized by visceral myopathy that involves the digestive and urinary tracts, and usually presents as intestinal pseudo-obstruction. Recently, a high rate of spontaneous chromosomal damage was found in blood lymphocytes of patients with hereditary megaduodenum, predictive of an increased cancer risk. Clinical manifestations of the disease vary, ranging from severe pseudo-obstruction to asymptomatic family members; recurrent urinary tract infections are common. Histology reveals vacuolar degeneration and fibrosis of the longitudinal layer of gastrointestinal muscle. This disease should be suspected in patients with an enlarged duodenum but no mechanical obstruction. Treatment is symptomatic and based on diet and control of bacterial overgrowth. Enteral or parenteral nutrition may be needed. Laterolateral duodenojejunostomy and gastrojejunostomy may sometimes be helpful to relieve obstructive symptoms. The risk of cancer in patients with hereditary megaduodenum is still unknown. This paper describes a family with hereditary megaduodenum in which one of the three affected members died of esophageal carcinoma and reviews the literature on the disease with particular attention to reports of cancer.

Oesophageal acid clearance in patients with systemic sclerosis: effect of body position

OBJECTIVE

To test the effect of body position on oesophageal acid clearance time in patients with systemic sclerosis.

DESIGN AND METHODS

Fifteen consecutive patients with systemic sclerosis and six healthy subjects underwent oesophageal manometry and an acid clearance test in three body positions (supine, recumbent at 30 degrees and seated at 90 degrees) in randomized order.

RESULTS

In healthy subjects the body position did not affect acid clearance time, whereas in patients the oesophagus cleared mainly by gravity. In patients the acid clearance time was significantly longer in the supine than in the seated position (P < 0.05). Nine patients did not have a detectable peristaltic wave in the distal oesophagus. In the other six oesophageal peristalsis was still detectable but contractions had reduced amplitude and often had double and triple peaks; also in this subgroup the acid clearance time recorded in the supine position was prolonged.

CONCLUSIONS

In systemic sclerosis gravity plays a major role in oesophageal acid clearance time. The finding of delayed acid clearance in a supine patient may suggest initial oesophageal involvement in the disease.

High spontaneous chromosomal damage in lymphocytes from patients with hereditary megaduodenum

Chromosomal aberration and micronucleus assays were used to investigate the extent of cytogenetic damage in peripheral blood lymphocytes from four patients in two unrelated families with hereditary megaduodenum. The frequencies of total chromosomal aberrations, which significantly correlated with those of micronuclei, were higher in the patients than in sex- and age-matched controls, with no overlapping between the two groups. The considerable chromosomal fragility in patients with hereditary megaduodenum may be a genotypic marker for preclinical diagnosis predictive of increased cancer risk.

Tonic responses of canine proximal colon: effects of eating, nutrients, and simulated diarrhea

Our hypothesis was that the proximal colon relaxes to accommodate flow from the ileum. Therefore, we recorded tonic responses of the canine proximal colon to flow through the ileum and colon stimulated by 1) an 840-kcal meal, 2) nutrients perfused into the ileum and colon, or 3) rapid infusion of saline into the ileum with overflow into the colon. Saline infusion was considered to be a model of diarrhea, and the effects of an antidiarrheal (morphine sulfate) were therefore assessed. Proximal colonic tone was measured with a barostat. Tone increased before and after the arrival of chyme in the ileocolonic region. Perfusion of nutrients into the ileum and colon also significantly increased (P < 0.05) colonic tone compared with equal volumes of saline. Rapid perfusion of the ileocolonic segment with saline increased colonic tone; this increase was significantly greater (P < 0.01) when preceded by morphine. In contrast to our hypothesis, tone of the canine proximal colon increased in response to ileal flow. The increase in colonic tone during the late response to food was at least partly attributable to stimulation by intraluminal contents.

A selective NK-2 antagonist blocks the increase of canine colonic tone and ileal contractions induced by the NK-2 selective receptor agonist, [beta Ala8] neurokinin A-(4-10)

BACKGROUND

The regulatory roles of tachykinins in intestinal motor function may be clarified by use of novel, stable and selective antagonists of neurokinin receptors. We studied the effects of the non-peptide NK-2 receptor antagonist SR48968 on canine colonic tone under resting conditions and after stimulation by the selective NK-2 receptor agonist [beta Ala8] neurokinin A-(4-10).

METHODS

Experiments were performed in three conscious female dogs. Proximal colonic tone was recorded by a barostat and intraluminal pressures were recorded in the terminal ileum. 10, 15 and 20 cm orad to the ileocaecal junction. In separate experiments, and in a random sequence, dogs received an i.v. injection of the NK-2 antagonist SR48968, 10, 100, 1000 micrograms/kg, followed after 30 min by 2 micrograms/kg of the agonist [beta Ala8] neurokinin A-(4-10). Experiments were replicated twice in each dog.

RESULTS

The NK-2 agonist increased colonic tone, and SR48968 antagonized these effects in a dose-dependent fashion (Spearman's rank, r = 0.86; P < 0.01); antagonism was complete at the highest dose. SR48968 alone had no effect on colonic tone and ileal motility. When given during phase I or II of the interdigestive motor complex, [beta Ala8] neurokinin A-(4-10) increased ileal contractions: pre-treatment with SR48968 blocked this increase in ileal motility. When given during phase III, [beta Ala8] neurokinin A-(4-10) interrupted the motility front; this effect was not antagonized by SR48968.

CONCLUSIONS

SR48968 antagonizes the increase in canine colonic tone and ileal motility induced by activation of NK-2 receptors. However, SR48968 by itself had no effect on the control of colonic tone and ileal motility under unstimulated conditions. SR48968 may be useful for investigating the physiological role of tachykinins on the gastrointestinal tract.

Manometric patterns of rat colonic motor activity and defecation. Effect of selective 5HT1A agonist 8-OH-DPAT

We investigated in conscious and unrestrained rats, the major patterns of colonic pressure waves, as related to defecation. A manometric low compliance perfusion system, which was set at a very low flow rate (0.03 ml/min), permitted simultaneous recordings of intraluminal pressure in the proximal, transverse, and distal colon. Pressure waves in control rats reflected two types of motor activity: short-duration waves (< 15 sec), that were frequent throughout the colon (about 40-90/hr with aborally decreasing frequency), and propulsive, long-duration, high-amplitude waves (> 15 sec, > 15 mm Hg) that occurred only occasionally (1/hr or less) in the transverse and distal, but not in the proximal colon; these waves appeared to migrate aborally and were associated with defecation. The serotonin 5HT1A agonist 8-OH-DPAT dramatically and dose-dependently increased the frequency of long-duration, high-amplitude waves in the transverse and distal colon, and concurrently promoted defecation; these effects were prevented by the putative 5HT1A antagonist pindolol. We conclude that 5HT1A agonists such as 8-OH-DPAT may promote defecation and occurrence of propulsive waves through the same serotoninergic mechanism.

Ileal distention relaxes the canine colon: a model of megacolon?

BACKGROUND/AIMS

Reflex relaxation is a mechanism whereby the colon can show short-term dilatation in the absence of mechanical obstruction. This study investigated the tonic response of the canine colon to ileal distention and its pharmacological control.

METHODS

In four dogs, the tone of the proximal colon was recorded by a barostat during distention of the terminal ileum.

RESULTS

Ileal distention inhibited ileal motility and relaxed the colon. Adrenergic blockade by propranolol plus phentolamine, nicotinic blockade by hexamethonium, and the nitric oxide synthase inhibitor N omega-nitro-L-arginine methylester significantly increased resting tone of the colon but did not inhibit relaxation induced by ileal distention. Muscarinic blockade by atropine completely relaxed the colon, and no further decrease in tone was observed after ileal distention. The neurokinin 2 antagonist SR48968 did not alter colonic tone.

CONCLUSIONS

The barostat was able to monitor resting tone of the canine colon, which was shown to be under inhibitory control by adrenergic, cholinergic-nicotinic, and nitric oxide-like transmitters. Inhibition of colonic tone by ileal distention was not mediated solely by adrenergic, cholinergic-nicotinic, or nitric oxide mechanisms. Reflex relaxation, possibly predisposing to acute colonic dilatation, may be activated by multiple mechanisms that may differ from those controlling resting tone.

Acid clearance and oesophageal sensitivity in patients with progressive systemic sclerosis

This study examined the hypothesis that impaired oesophageal peristalsis was associated with delayed oesophageal clearance of acid in patients with progressive systemic sclerosis (PSS), some of whom are thought to have impaired oesophageal sensitivity to acid. Sixteen patients with PSS had: (a) oesophageal manometry and endoscopy; (b) acid perfusion of the oesophagus with simultaneous measurement of intraoesophageal pH during perfusion and for the next 10 minutes; (c) 22 hour monitoring of intraoesophageal pH; and (d) an evaluation of reflux symptoms during and after perfusion and during overnight pH monitoring. By oesophageal manometry, eight patients had normal peristalsis and eight patients had impaired peristalsis. Oesophageal endoscopy was unremarkable in patients with normal peristalsis, whereas all patients with impaired peristalsis had oesophagitis. The time needed to clear the oesophagus of perfused acid was shorter (p < 0.01) in patients with normal peristalsis and acid clearance time was significantly correlated (p < 0.01) with acid exposure time during overnight pH monitoring. During and after oesophageal perfusion, the nature, duration, and severity of symptoms did not differ between the groups, but overnight symptoms lasted longer (p < 0.05) in patients with impaired peristalsis. It is concluded that in PSS: (1) Impaired oesophageal motility delayed the clearance of acid and increased the exposure time to acid. (2) Acid clearance time is a useful parameter of impaired oesophageal motor function. The assessment of acid clearance time can be used as an alternative to overnight pH monitoring, to assess the impairment of oesophageal acid clearance. (3) Oesophageal sensitivity to acid was preserved in patients with impaired peristalsis and oesophagitis. (4) Reflux symptoms lasted longer in patients with prolonged oesophageal acid exposure but were still reported for a small fraction of the total acid exposure time. Thus, reflux symptoms reflect poorly prolonged exposure of the oesophagus to acid and are not a reliable guide to acid injury of the oesophagus in PSS.

Anorectal dysfunction and delayed colonic transit in patients with progressive systemic sclerosis

We studied 14 unselected patients with progressive systemic sclerosis (PSS), six with constipation, and eight with normal bowel habits. A control group, matched for age and sex, comprised six patients with idiopathic constipation and seven healthy subjects. Anorectal manometry was performed with perfused catheters and segmental colonic transit was measured by a radiopaque marker technique. The resting pressure of the anal canal was significantly reduced in PSS with constipation (P < 0.05). The rectoanal inhibitory reflex was detected in only one PSS patient with constipation, but was present in seven of eight PSS patients with normal bowel habits and in all controls (P < 0.01). Total and right colonic transit times were significantly delayed in PSS with constipation and in patients with idiopathic constipation (P < 0.05). In patients with PSS, colonic transit was delayed and anal sphincter function was impaired in constipated patients, suggesting involvement of both the colon and the anorectum by the disease.

Single doses of ritodrine delay orocaecal transit in patients with irritable bowel syndrome

The lactulose hydrogen breath test was used to assess the effect of a single dose of the beta 2-adrenoceptor agonist ritodrine on orocaecal transit time in 11 patients (three men) with irritable bowel syndrome. Transit time (median values, range) was significantly longer (P less than 0.01) after ritodrine than after placebo (120, 50-200 vs 75, 40-100 min). Median heart rate was similar before treatments whereas the maximal increase in heart rate was significantly greater (P less than 0.01) after ritodrine than after placebo.

Risk factors for first operation in Crohn's disease

We studied 267 consecutive Italian patients (146 male, 121 female) with Crohn's disease. Median time from the first symptom to diagnosis at our center was 21 months (range 1-372), whereas median follow-up from the first visit was 38 months (range 1-180). The disease affected the small bowel in 93 (35%) cases, the ileum and colon in 76 (28%), and the colon in 98 (37%). Forty-nine percent of the patients underwent major abdominal surgery for the disease at least once. The cumulative probability of abdominal surgery was 36% and 55%, 60 and 120 months after the onset of symptoms, respectively. Univariate analysis indicated that patients with colon involvement (p less than 0.0001), those with a longer interval between first symptom and diagnosis (p less than 0.0001), and those at an older age at diagnosis (p less than 0.0003) had a significantly greater probability of escaping abdominal surgery. The interval between first symptom and diagnosis, the site of disease, and the age at diagnosis were confirmed as risk factors for surgery, in decreasing order of importance, by multivariate analysis with Cox's proportional hazard model. A prognostic index for first operation based on these variables is proposed.

Orocecal transit delay in obese patients

Orocecal transit time was assessed with lactulose hydrogen breath test in 12 obese patients during intravenous infusion of placebo or naloxone 40 micrograms/kg/hr given in randomized order and in double-blind conditions. Transit time was also evaluated in 22 healthy controls. Orocecal transit was significantly (P less than 0.01) longer in the obese patients, during placebo treatment (median 130, range 100-200 min) than in the healthy controls (median 75, range 40-170 min). Compared with placebo, transit time in the obese subjects was delayed (P less than 0.05) during naloxone treatment (median 150, range 100-230 min).

Intragastric and intraoesophageal pH monitoring in duodenal ulcerpatients: effect of the new histamine H2-receptor antagonist ramixotidine

The effect of the new histamine H2-receptor antagonist ramixotidine 750 mg p.o., administered at 22.00 h, on intragastric and intraoesophageal pH monitored from 22.00 h to 08.00 h, was studied in a double-blind cross-over trial in 11 duodenal ulcer patients. Placebo and ramixotidine were given to each patient on 2 consecutive days in a randomized sequence. Three patients were excluded from the intragastric pH analysis as the records on the second study day were technically inadequate. No significant carry-over or sequence effect was noted. Intragastric hydrogen ion activity was significantly lower (p = 0.01) after ramixotidine than after placebo: median (range) 24 (9-100) vs 97 (27-188) mmol/l. The percentage of time with intraoesophageal pH less than 4 was less than 5% in all but three recordings, with a maximum value of 12%, and it was not significantly different after the two treatments.

Repeatability of lactulose hydrogen breath test in subjects with normal or prolonged orocecal transit

The within-subject repeatability of orocecal transit assessed with lactulose hydrogen breath test was evaluated in 15 healthy volunteers and 16 constipated or obese patients. The test was repeated twice in each subject. Mean (SD) transit time was 105 (63) and 103 (60) min in the first and second series of tests, respectively, showing that the first measurement did not affect the second. The within-subject repeatability of the test was related to the length of transit, the scatter of the differences between the first and second test being greater with the increase of the mean gastrointestinal transit time. The 95% coefficient of repeatability was 84 min for all measurements and 30 and 118 min, respectively, for transit times under and over 100 min. The lowest reproducibility of the test was found in constipated patients with prolonged orocecal transit.

Plasma prolactin, sex steroids and gastrin in human volunteers treated for 2 weeks with therapeutic doses of cimetidine or the new histamine H2-receptor antagonist ramixotidine (CM 57755A)

Three groups of eight healthy male volunteers received placebo for 2 days, then daily morning doses either of cimetidine 800 mg, ramixotidine 750 mg (CM 57755A), or placebo, for 14 days, and then were all returned to placebo for one more day. Plasma levels of prolactin, testosterone and 17 beta-estradiol were measured on Days 2, 3, 16 and 17 in blood samples taken 30 and 15 min before and 0, 60, 120, 180, 240 and 300 min after treatment. Gastrin was assayed in blood collected on the same days 180 min after treatment. Mean pre- and post-treatment areas under the time-concentration curves of the first three hormones were not significantly different in the three groups on any test day, or within the same group throughout the four test days. Mean plasma gastrin levels ranged between 27 and 42 pg/ml, respectively, in the placebo and cimetidine treated groups on test day 3, and intermediate values were found in the group receiving CM 57755A. There was no statistically significant difference in gastrin level between the groups on any test day or within the same group throughout the four test days. No subjective side-effects attributable to the treatments were reported, and there were no abnormalities in blood pressure, heart rate or standard laboratory tests.

Oral naloxone antagonizes loperamide-induced delay of orocecal transit

Orocecal transit time was determined by the lactulose hydrogen breath test in nine healthy volunteers after administration of placebo, loperamide (16 mg per os), and loperamide (16 mg per os) followed by oral naloxone at doses of 16 and 32 mg. The four tests were performed in double-blind conditions and in random sequences. Transit time (mean, SD) after loperamide (128.8 min, 32.9) was significantly increased (P less than 0.05) compared with placebo (85.5 min, 35.7), loperamide followed by naloxone 16 mg (88.8 min, 46.2), and loperamide followed by naloxone 32 mg (84.4 min, 40.6). These results show that the peripheral opioid agonist loperamide delays orocecal transit in healthy subjects and that naloxone per os at adequate doses antagonizes this effect.

Inhibition of pentagastrin-stimulated gastric acid secretion and plasma levels of the new histamine H2-receptor antagonist ramixotidine dihydrochloride (CM 57755) in human volunteers

The new competitive histamine H2-receptor antagonist, ramixotidine 2 HCl (CM 57755), has been tested in healthy male volunteers for its ability to inhibit pentagastrin-stimulated gastric acid secretion. In the first study, in 8 subjects, pentagastrin 6 micrograms.kg-1 was injected s.c., 90 min after the following 4 oral treatments given in random order at weekly intervals: placebo, 100, 200 and 400 mg CM 57755. Gastric contents were collected over 15-min periods during the 2 h after pentagastrin stimulation. In a second, similar study, 8 subjects received placebo, 0.5 and 1.0 g CM 57755 and 800 mg cimetidine, 120 min before a 2 h i.v. infusion of 6 micrograms.kg-1.h-1 pentagastrin. Cumulative gastric secretion in placebo-treated subjects was 46 +/- 14 and 62 +/- 11 mmol H+.2 h-1 (mean +/- SD), respectively, in the first and second studies. It was significantly reduced only after 400 mg CM 57755 in the first study. In the second study either dose of CM 57755 and cimetidine caused a significant reduction in gastric acid secretion. Average plasma levels of ramixotidine were dose-related after 0.2 and 1.0 g and ranged from 0.3 and 1.6 micrograms/ml, respectively, at 60 min to 0.5 and 3.7 micrograms/ml at 180 min. The peak cimetidine level averaged 3.6 micrograms/ml at 150 min. Individual CM 57755 plasma levels throughout the test period were fairly consistent with the inhibition of cumulative gastric acid secretion scored concurrently in each subject. No subjective side-effects attributable to the treatments were reported, and no abnormal findings were seen in the ECG or in laboratory tests.

Effect of loperamide and naloxone on mouth-to-caecum transit time evaluated by lactulose hydrogen breath test

The effect of loperamide and naloxone on mouth-to-caecum transit time was evaluated by the lactulose hydrogen breath test in four men and four women. Each subject underwent tests during the administration of placebo, loperamide (12-16 mg po), naloxone (40 micrograms/kg/h by a three-hour intravenous infusion), and loperamide plus naloxone, carried out at intervals of one or two weeks. The transit time was significantly longer after loperamide, and this effect was antagonised by the concomitant administration of naloxone whereas naloxone administered alone had no effect on mean transit time. No clinically important side effects were reported.

Treatment of 'cimetidine-resistant' chronic duodenal ulcers with ranitidine or cimetidine: a randomised multicentre study

Forty patients with endoscopically proven persistent duodenal ulcer who had been treated for six weeks with cimetidine (1 g/day) were randomly allocated to receive a further six weeks' treatment with cimetidine (1 g/day) or ranitidine (300 mg/day). Ulcers healed in 12 of 19 patients given cimetidine (63%) and in 13 of 21 given ranitidine (62%); two patients on cimetidine and two on ranitidine dropped out. In the unhealed ulcer group the ulcer size was reduced in most patients. There was no change in basal acid output, peak acid output, plasma gastrin and pepsinogen I levels after either treatment. Clinical data, gastric function tests, and endoscopic features did not predict ulcer healing. Both treatments were effective in the relief of pain: 72% of patients with unhealed ulcers were asymptomatic at the end of the trial.

Secretin-induced gastrin response in the Zollinger-Ellison syndrome and chronic duodenal ulcer patients before and after cimetidine treatment

A secretin provocative test was performed in 16 patients with chronic duodenal ulcer and in five patients with the Zollinger-Ellison syndrome. In four chronic duodenal ulcer patients a second secretin test was done during acute iv cimetidine administration. There were only slight variations of gastrin compared with the first test. A third test was done on the same four chronic duodenal ulcer patients after 1 month's po cimetidine treatment (1 g/day); gastrin at 0 time was significantly higher than in the previous two tests (p less than 0.01). Integrated gastrin response after secretin was significantly lower in the third test than in the first (p less than 0.05). In two Zollinger-Ellison syndrome patients treated with 1.0 and 1.4 g/day cimetidine for 3 months, gastrin at 0 time was not markedly increased, whereas compared with the first test gastrin levels were higher at each time after secretin. These data suggest that previous cimetidine treatment does not alter, and may even increase, the diagnostic sensitivity of the secretin test.

Effects of somatostatin infusion in four patients with malignant carcinoid syndrome

Somatostatin (4 micrograms/min, cyclic form) was infused for 24 h on six occasions in four patients with carcinoid ileal tumor and multiple liver metastases. During infusion, spontaneous flushes and/or diarrhea were markedly reduced with a return to the pretreatment pattern on the next day. Urinary 5-hydroxyindole acetic acid excretion and plasma gastrin were not significantly changed, whereas plasma insulin presented the expected decrease and rebound. These results confirm that carcinoid symptoms are somatostatin-sensitive but do not provide evidence that serotonin or gastrin play a major role in inducing these symptoms.