Electrochemical detector for breath hydrogen determination: measurement of small bowel transit time in normal subjects and patients with the irritable bowel syndrome

Association of serotonin transporter promoter polymorphism (5-HTTLPR) with orocecal transit time in irritable bowel syndrome

BACKGROUND

Irritable bowel syndrome (IBS) is a multifactorial disorder with altered intestinal motility, secretion, and sensation. Serotonin (5-HT) stimulates gut motility and alters serotonin signaling that may lead to both intestinal and extraintestinal symptoms in IBS.

AIM

The aim of this study was to examine the association of serotonin transporter gene promoter polymorphism (5-HTTLPR) in IBS with orocecal transit time (OCTT) measured by lactulose hydrogen breath test.

METHOD

This prospective case-control study included 151 IBS patients (mean±SD 37.4±11.6 years, median 36, range 19-68). Ninety-two patients were diarrhea-predominant IBS (D-IBS), 44 constipation-predominant IBS (C-IBS), 15 alternating diarrhea and constipation IBS (M-IBS), and 100 healthy controls (mean±SD 37.2±11.4 years, median 36, range 20-64 years). 5-HTTLPR gene polymorphism was studied by polymerase chain reaction-based method. 5-HT levels were measured by enzyme-linked immunosorbent assay (ELISA). Orocecal transit time (OCTT) was measured by a non-invasive lactulose hydrogen breath test. OCTT was also compared with respect to 5-HTTLPR genotypes in different IBS phenotypes.

RESULTS

Serum serotonin levels were significantly higher in overall IBS patients (152±77 ng/mL, p<0.001), D-IBS (184±76 ng/mL, p<0.001), compared to healthy controls (129±56 ng/mL). There was no difference in 5-HT levels between C-IBS (124±53 ng/mL) and controls. In the case of M-IBS, 5-HT levels were (88±49 ng/mL p<0.05) significantly lower than that of controls. OCTT was significantly shorter in D-IBS patients (95±36 min) as compared to controls (112±41 min). In contrast, C-IBS showed significantly prolonged OCTT (136±54 min). There was a significant difference in OCTT between D-IBS and C-IBS patients (p<0.001). There was no significant association found between OCTT and 5-HTTLPR.

CONCLUSIONS

Serum serotonin concentrations were increased in D-IBS compared to controls and C-IBS. OCTT was shorter in D-IBS and delayed in C-IBS patients. There was no association of 5-HTLPR polymorphism with OCTT.

European guideline on indications, performance, and clinical impact of hydrogen and methane breath tests in adult and pediatric patients: European Association for Gastroenterology, Endoscopy and Nutrition, European Society of Neurogastroenterology and Motility, and European Society for Paediatric Gastroenterology Hepatology and Nutrition consensus

Introduction

Measurement of breath hydrogen (H₂) and methane (CH₄) excretion after ingestion of test‐carbohydrates is used for different diagnostic purposes. There is a lack of standardization among centers performing these tests and this, together with recent technical developments and evidence from clinical studies, highlight the need for a European guideline.

Methods

This consensus‐based clinical practice guideline defines the clinical indications, performance, and interpretation of H₂‐CH₄‐breath tests in adult and pediatric patients. A balance between scientific evidence and clinical experience was achieved by a Delphi consensus that involved 44 experts from 18 European countries. Eighty eight statements and recommendations were drafted based on a review of the literature. Consensus (≥80% agreement) was reached for 82. Quality of evidence was evaluated using validated criteria.

Results

The guideline incorporates new insights into the role of symptom assessment to diagnose carbohydrate (e.g., lactose) intolerances and recommends that breath tests for carbohydrate malabsorption require additional validated concurrent symptom evaluation to establish carbohydrate intolerance. Regarding the use of breath tests for the evaluation of oro‐cecal transit time and suspected small bowel bacterial overgrowth, this guideline highlights confounding factors associated with the interpretation of H₂‐CH₄‐breath tests in these indications and recommends approaches to mitigate these issues.

Conclusion

This clinical practice guideline should facilitate pan‐European harmonization of diagnostic approaches to symptoms and disorders, which are very common in specialist and primary care gastroenterology practice, both in adult and pediatric patients. In addition, it identifies areas of future research needs to clarify diagnostic and therapeutic approaches.

A double blind, placebo-controlled, randomized clinical trial that breast milk derived-Lactobacillus gasseri BNR17 mitigated diarrhea-dominant irritable bowel syndrome

The exact pathogenesis of diarrhea-dominant irritable bowel syndrome (IBS) is not known, but the abnormal microbiota of the gastrointestinal tract is considered to be one of the important contributing factors as in other gastrointestinal diseases such as inflammatory bowel disease, antibiotic-associated diarrhea, and colorectal cancer as well as systemic diseases. Though diverse trials of probiotics had been continued in the treatment of diarrhea-IBS, only a few proved by randomized clinical trial. To prove the efficacy of Lactobacillus gasseri BNR17 isolated from breast milk in patients with diarrhea-IBS, prospective, randomized, placebo controlled clinical trial was done including health related-quality of life analysis, colon transit time, and the changes of fecal microbiota. BNR17 significantly improved the symptoms of diarrhea compared to control group. Health related-QOL analysis showed significant improvement of abdominal pain, distension, disturbed daily life, and mean defecation frequency with BNR17. On comparative CTT before and after BNR17, 6 out of 24 subjects showed significant correction of rapid colon transit pattern, while only 2 out of 24 in placebo (p<0.01). Upon fecal microbiota analysis, BNR17 significantly increased B. fecalis, E. rectale, C. aerofaciens, F. prausnitzil and B. steroris. Conclusively, Lactobacillus gasseri BNR17 can be a potential probiotics to ameliorate diarrhea-IBS.

Computational postprocessing quantification of small bowel motility using magnetic resonance images in clinical practice: An initial experience

PURPOSE

To study the feasibility and to gauge the potential clinical impact of quantifying small bowel motility using magnetic resonance imaging (MRI) in a larger population with a spectra of gastrointestinal conditions with impaired small bowel motility.

MATERIALS AND METHODS

Data were gathered retrospectively from a cohort of 127 patients undergoing MR enterography (1.5 Tesla) in 2011. Cine motility sequences were processed with validated motility analysis software and a parametric motility map was generated. Regions of interests were drawn in the jejunum, ileum, and terminal ileum, and Jacobian standard deviation mean motility index' score (MIS) was calculated. Patients were divided into Crohn's disease (CD), ulcerative colitis, irritable bowel syndrome, and healthy subjects.

RESULTS

In CD, terminal ileum motility was lower in comparison to healthy subjects (mean difference: -0.1052 arbitrary units, 95% confidence interval: -0.1981--0.0122, P = 0.018). Subgrouping of CD showed that the difference was recognized in patients with disease limited to the small bowel (mean difference: -0.1440 arbitrary units, 95% confidence interval: -0.2491--0.0389, P = 0.002). Visible dysmotility of terminal ileum on MRI reflected a reduced MIS compared with normal motility (0.22 ± 0.09 and 0.33 ± 0.15 arbitrary units, respectively, P = 0.043). Motility correlated negatively between ileum and age (P = 0.021), and between terminal ileum and C-reactive protein in ulcerative colitis (P = 0.031).

CONCLUSION

Motility quantitation revealed a significant difference in motility of terminal ileum in patients with small bowel CD compared with healthy subjects, concording with visible dysmotility and inflammatory changes. J. Magn. Reson. Imaging 2016;44:277-287.

In vitro validation of the lactose 13C-ureide breath test for equine orocaecal transit time measurement

REASONS FOR PERFORMING STUDY

Validation of a reliable, noninvasive clinical test for quantification of equine orocaecal transit time (OCTT) is required. This would facilitate an evidence-based approach to investigation and treatment of equine small intestinal disorders.

OBJECTIVES

1) Comparison of the lactose (13) C-ureide breath test (LUBT) with the hydrogen breath test (H(2) BT) for OCTT measurement. 2) Identification of the characteristics of gastrointestinal microbial glycosylureide hydrolase activity in vitro. 3) Production of an optimised protocol for the LUBT for in vivo measurement of equine OCTT.

HYPOTHESIS

Significant lactose (13) C-ureide ((13) C-LU) hydrolase activity is restricted to the large bowel. The rate of expiratory (13) CO(2) production after ingestion of the isotope will provide an indirect quantifiable measure of orocaecal transit rate. Requisite bacterial activity may be enhanced by a primer dose of unlabelled substrate as shown in Man.

METHODS

Combined LUBT and H(2) BT were performed in 8 healthy individuals. Analysis of sequential end expiratory breath samples was used to calculate OCTT and results compared. Digestion of (13) C-LU was investigated in vitro using fresh faecal material or intestinal aliquots collected post mortem. Isotopic fermentation rate was measured by rate of appearance of (13) CO(2) .

RESULTS

Peaks in expiratory (13) CO(2) occurred in all individuals after ingestion of the labelled test meal, whereas H(2) expiration was variable. Both faecal and intestinal microbial digestion of (13) C-LU were maximised by prior exposure to (12) C-LU. Induced bacterial glucoseureide hydrolase activity was significantly greater in the caecum than in the small intestine (n = 10, P<0.05).

CONCLUSIONS

Significant (13) C-LU digestion is restricted to the equine large intestine under normal conditions, and is enhanced by prior exposure to (12) C-LU, making (13) C-LU a suitable noninvasive marker of equine OCTT. The LUBT is more reliable than the H(2) BT for measurement of equine OCTT.

Asian motility studies in irritable bowel syndrome

Altered motility remains one of the important pathophysiologic factors in patients with irritable bowel syndrome (IBS) who commonly complain of abdominal pain and stool changes such as diarrhea and constipation. The prevalence of IBS has increased among Asian populations these days. Gastrointestinal (GI) physiology may vary between Asian and Western populations because of differences in diets, socio-cultural backgrounds, and genetic factors. The characteristics and differences of GI dysmotility in Asian IBS patients were reviewed. MEDLINE search work was performed including following terms, 'IBS,' 'motility,' 'transit time,' 'esophageal motility,' 'gastric motility,' 'small intestinal motility,' 'colonic motility,' 'anorectal function,' and 'gallbladder motility' and over 100 articles were categorized under 'esophagus,' 'stomach,' 'small intestine,' 'colon,' 'anorectum,' 'gallbladder,' 'transit,' 'motor pattern,' and 'effect of stressors.' Delayed gastric emptying, slow tansit in constipation predominant IBS patients, rapid transit in diarrhea predominant IBS patients, accelerated motility responses to various stressors such as meals, mental stress, or corticotrophin releasing hormones, and altered rectal compliance and altered rectal accomodation were reported in many Asian studies regarding IBS. Many conflicting results were found among these studies and there are still controversies to conclude these as unique features of Asian IBS patients. Multinational and multicenter studies are needed to be performed vigorously in order to elaborate characteristics as well as differences of altered motililty in Asian patients with IBS.

The effects of melatonin on colonic transit time in normal controls and IBS patients

OBJECTIVES

The role of melatonin in regulating gut motility in human subjects is not clear. The aim of this study was to investigate the effects of exogenous melatonin on colonic transit time (CTT) in healthy subjects and in patients with irritable bowel syndrome (IBS).

METHODS

Colonic transit time was measured in 17 healthy controls using the radio-opaque, blue dye, and Bristol stool form score method before and after 30 days of melatonin treatment 3 mg daily. A double blind cross-over study aimed at measuring CTT was also performed in 17 matched IBS patients using the blue dye and Bristol stool form score methods. The patients were randomized and received either melatonin 3 mg or placebo daily for 8 weeks, followed by a 4-week washout, and then placebo or melatonin in the reverse order for a second 8-week period.

RESULTS

The melatonin treatment of the control subjects caused an increase in CTT (mean+/-SD) from 27.4+/-10.5 to 37.4+/-23.8 h (P=0.04). Compared with the CTT of the controls (25.2+/-7.7), that of the constipation-predominant IBS patients appeared prolonged-65.2+/-33.3 h (P<0.01). The CTT did not change significantly in IBS patients after melatonin treatment.

CONCLUSION

Melatonin may be a promising candidate for the future research of agents that can modulate bowel motility.

Inhibition of Phosphodiesterase Type 4 Decreases Stress-Induced Defecation in Rats and Mice

BACKGROUND/AIMS

Phosphodiesterase type 4 (PDE4) has been previously shown to regulate colonic contractile activity in vitro. In this study, the effects of PDE4 inhibition were assessed in a model of stress-induced defecation previously demonstrated to be due to increased colonic transit/evacuation.

METHODS

Rats were individually placed in a mild restraint cage and placed into a 12 degrees C environment (cold-restraint stress) for 60 min. Mice received restraint (only) stress at room temperature for 30 min. Loperamide (positive control compound) or two different PDE4 inhibitors (rolipram and roflumilast) were administered orally at several doses to the rodents 1 h before stress began. Vehicle alone was administered for comparison. The number of fecal pellets expelled during stress (fecal pellet output), total fecal pellet wet weight and total fecal water content were measured.

RESULTS

Loperamide produced a dose-related decrease (ID(50)s in mg/kg) in fecal pellet output (rat = 7.4, mouse = 0.7) and significantly decreased fecal wet weight (72.9%) and decreased fecal percent water content (9.4%). The two PDE4 inhibitors produced a similar dose-related inhibition of fecal pellet output. Rolipram exhibited ID(50)s in rat and mouse of 14.1 and 27.1, respectively. Rolipram significantly decreased fecal wet weight (58.8%) but increased fecal percent water content (15.0%). For roflumilast, ID(50)s were 24.2 mg/kg and 12.4 in the rat and mouse, respectively. Although roflumilast also significantly (p < 0.05) decreased fecal wet weight (47.2%), it did not significantly increase fecal percent water content.

CONCLUSIONS

These data indicate that PDE4 inhibition is effective in reducing rodent stress-induced defecation, provides the first functional data on a potential role for PDE4 activity in the colonic evacuation response to stress, and indicates the potential utility of PDE4 inhibitors in functional bowel disease such as irritable bowel syndrome requires further evaluation.

Influence of age and body size on orocecal transit time as assessed by use of the sulfasalazine method in healthy dogs

OBJECTIVE

To compare orocecal transit time (OCTT) as assessed by use of the sulfapyridine appearance time in plasma after oral administration of sulfasalazine in dogs of varying age and body size and determine whether OCTT correlates with fecal quality.

ANIMALS

6 Miniature Poodles (MP), 6 Standard Schnauzers (SS), 6 Giant Schnauzers (GS), and 6 Great Danes (GD).

PROCEDURE

Determinations of OCTT were made at 12, 22, 36, and 60 weeks of age. Dogs were fed sulfasalazine mixed with a meal. Blood samples were then collected for 6 hours. The OCTT was the time from ingestion of the meal to detection of sulfapyridine in plasma. Fecal moisture content and consistency were recorded during the same periods.

RESULTS

Mean OCTT decreased during growth of GS and GD dogs. No correlation was found between OCTT and fecal variables during growth in the 4 breeds. Effect of body size was observed at 12 and 22 weeks of age, with a longer OCTT in GS and GD than in MP and SS dogs. Similar OCTTs were observed at 36 and 60 weeks of age in all breeds, although GS and GD dogs had poorer fecal quality during those periods.

CONCLUSIONS AND CLINICAL RELEVANCE

An effect of age on OCTT was observed only in large-breed dogs, with longer transit times in puppies (12 weeks old) than in adults (60 weeks old). Mean OCTT is not correlated with body size in adult dogs. No relationship was detected between OCTT and fecal variables in healthy dogs.

Racecadotril versus loperamide: antidiarrheal research revisited

Racecadotril is an enkephalinase inhibitor, presented as a purely antisecretory agent with advantages over the opiate-receptor agonist loperamide in the treatment of diarrhea. A critical review of the literature and the models used was performed. Although pretreatment with high doses of racecadotril reduced cholera toxin-induced secretion and although clinical efficacy was demonstrated in young infants--a population characterized by 10-fold higher plasma enkephalin concentrations compared with adults, the analysis calls into question the peripheral antisecretory selectivity and relative clinical efficacy. Conversely, loperamide can be proposed as an antisecretory agent at therapeutic concentrations. Its efficacy is well established in acute and chronic diarrhea. Current experimental and clinical comparative studies of both drugs have problems with regard to the selection of the doses, the validity of models, and/or the trial design. The conclusion is that more research is needed before reliable conclusions can be drawn on the place of racecadotril in diarrhea treatment.

Guidelines for adults on self-medication for the treatment of acute diarrhoea

Acute uncomplicated diarrhoea is commonly treated by self-medication. Guidelines for treatment exist, but are inconsistent, sometimes contradictory, and often owe more to dogma than evidence. An ad hoc multidisciplinary group has reviewed the literature to determine best practice. In general it is recognized that treatment of acute episodes relieves discomfort and social dysfunction. There is no evidence that it prolongs the illness. Self-medication in otherwise healthy adults is safe. Oral loperamide is the treatment of choice. Older anti-diarrhoeal drugs are also effective in the relief of symptoms but carry the risk of unwanted adverse effects. Oral rehydration solutions do not relieve diarrhoea, and confer no added benefit for adults who can maintain their fluid intake. Probiotic agents are, at present, limited in efficacy and availability. Antimicrobial drugs, available without prescription in some countries, are not generally appropriate for self-medication, except for travellers on the basis of medical advice prior to departure. Medical intervention is recommended for the management of acute diarrhoea in the frail, the elderly (> 75 years), persons with concurrent chronic disease, and children. Medical intervention is also required when there is no abatement of the symptoms after 48 h, or when there is evidence of deterioration such as dehydration, abdominal distension, or the onset of dysentery (pyrexia > 38.5 degrees C and/or bloody stools).

Gastrointestinal motility in patients with irritable bowel syndrome studied by using radiopaque markers

BACKGROUND

Irritable bowel syndrome (IBS) has been identified as a physiologic abnormality, but no test has been established as a diagnostic standard for gastrointestinal dyskinesia in IBS patients. The aim of this study was to investigate gastrointestinal motility in patients with IBS by using radiopaque markers.

METHODS

Gastrointestinal motility was studied in IBS patients (n = 72), constipation patients (n = 19), diarrhoea patients (n = 9), and healthy controls (n = 23). Using three types of radiopaque markers, analysis was performed to establish the transit time and a new indicator, the 'scattering index'.

RESULTS

Transit times were not characteristic in IBS. The patients with IBS had significantly higher scattering indexes in the colon and total gut than the healthy controls and the patients with constipation and diarrhoea. The transit time and scattering index of the colon were linearly correlated in the healthy controls and the constipation and diarrhoea patients but were not correlated in the IBS patients. Using transit time and scattering index was a reliable means of evaluating gastrointestinal motility in IBS patients, with a sensitivity of 65% and a specificity of 96%.

CONCLUSION

Three days' use of the radiopaque marker method was useful for providing an objective means of detecting gastrointestinal dysmotility in IBS patients.

Motility disorders in childhood

Motility disorders are very common in childhood, causing a number of gastrointestinal symptoms: recurrent vomiting, abdominal pain and distension, constipation and obstipation, and loose stools. The disorders result from disturbances of gut motor control mechanisms caused by either intrinsic disease of nerve and muscle, central nervous system dysfunction or perturbation of the humoral environment in which they operate. Intrinsic gut motor disease and central nervous system disorder are most usually congenital in origin, and alterations of the humoral environment acquired. Irritable bowel syndrome occurs in children as well as adults and is multifactorial in origin, with an interplay of psychogenic and organic disorders.

Effects of loperamide on ileoanal pouch function

BACKGROUND

Opioid analogues are used to manage increased bowel frequency in patients with an ileoanal reservoir. The aim of the study was to determine the clinical efficacy of loperamide in patients with an ileoanal reservoir and to assess its effect on pouch motility.

METHODS

Fourteen patients with a pouch who had normal pouch emptying and anal function were studied. Ambulatory pouch and anal motility, and stool weights, were recorded for 24 h while taking no medication and for 24 h while receiving 8 mg loperamide. In a second analysis, patients were divided on the basis of bowel frequency into those with 4 or fewer motions (good function; n=6) and those with more than 6 per day (poor function; n=8), to determine any differential effects of loperamide.

RESULTS

Loperamide decreased median bowel frequency (no loperamide 5.5 versus loperamide 4.0, P=0.03) and 24-h stool weight (610 g versus 413 g, P=0.03) but not individual stool weights. Patients with poor function had both higher bowel frequency (8.0 versus 3.5 per 24 h, P=0.004) and higher stool weight (728 g versus 430 g, P=0.05) with no treatment than those with good function. High-amplitude pouch pressure waves were greater in number before defaecation in patients with poor function and did not decrease with loperamide, in contrast to patients with good function. Pouch baseline pressure decreased after defaecation to a similar extent in both groups and was not affected by loperamide.

CONCLUSION

Loperamide 8 mg per day reduces bowel frequency by reducing total stool weight, not individual stool weights. In patients with good function it also affects pouch motility. High bowel frequency is associated with increased pouch high-pressure waves.

A one-hour active coping stressor reduces small bowel transit time in healthy young adults

OBJECTIVE

To examine the effect of a prolonged active coping stressor on the transit of a substance from the mouth through small intestine in normal human volunteers.

METHOD

Twelve healthy undergraduate males were administered 10 g of the nonabsorbable carbohydrate lactulose in two experimental sessions. In normal individuals, lactulose produces hydrogen gas upon exposure to bacteria residing in the colon. Repeated measurements of breath hydrogen were obtained for 2 hours. In one session, subjects rested quietly for the 2-hour period. In the other counterbalanced session, subjects avoided mild electric shocks by playing videogames for the first hour.

RESULTS

Stress produced a statistically and clinically significant reduction in mean transit time, from 79 to 55 minutes. The magnitude of stress-induced reduction in small bowel transit time was significantly correlated with change in an index of cardiac sympathetic activity, pulse transit time.

CONCLUSIONS

A prolonged active coping stressor with minimal motor requirements produced a decrease in small bowel transit time comparable with that observed in several studies of the effects of physical exercise and in comparisons between normal controls and patients with diarrhea-predominant irritable bowel syndrome.

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.

Therapeutic strategies for motility disorders. Medications, nutrition, biofeedback, and hypnotherapy

Gastrointestinal motility is regulated by a complex balance of inhibitory and excitatory neuronal, humoral, and mechanical factors. The goal in the management of motility disorders is to maintain adequate nutrition while decreasing symptoms. This can be accomplished by medications and support of nutrition and biofeedback; the application of these therapeutic strategies to patients with gut motility disorders is reviewed.

Orocecal transit time in humans assessed by sulfapyridine appearance in saliva after sulfasalazine intake

PURPOSE

We propose a noninvasive method for the measurement of orocecal transit time assessed by the sulfapyridine appearance time in saliva after ingestion of sulfasalazine.

METHOD

In 12 healthy volunteers, we studied the correlation between plasma and saliva sulfapyridine appearance times and then the sulfapyridine appearance times in saliva under various experimental conditions to assess the reproducibility, the effects of meals, and the role of the formulation, and the effects of gastrointestinal kinetic drugs.

RESULTS

The correlation between saliva and plasma sulfapyridine appearance times was strong (r = 0.84; p = 0.0004). The sulfapyridine saliva appearance time was significantly delayed by the meal. Compared with placebo, the saliva sulfapyridine appearance time was reduced by cisapride (312 +/- 128 versus 551 +/- 97 minutes; p = 0.0001) and increased by loperamide (674 +/- 267 versus 501 +/- 131 minutes; p = 0.044).

CONCLUSION

We propose the salivary sample method as a validated simplification of the plasma sulfasalazine-sulfapyridine test for the measurement of orocecal transit time.

Effect of a tricyclic antidepressant on small intestinal motility in health and diarrhea-predominant irritable bowel syndrome

Antidepressants are used in irritable bowel syndrome (IBS) and may have effects on the gut independent of improving mood. We have investigated the actions of a tricyclic antidepressant on small intestinal motor function in eight healthy volunteers and in six patients with diarrhea-predominant IBS. Fasting ambulatory motility was recorded from six small intestinal sites for 16-18 hr while on no drug (baseline) and while taking imipramine for five days. Orocecal transit time (OCTT) was measured by lactulose hydrogen breath test, during baseline and imipramine administration. Imipramine did not alter migrating motor complex periodicity, but slowed jejunal phase III propagation velocity in controls from 7.5 +/- 1.1 to 3.6 +/- 0.5 cm/min (P < 0.01) and in IBS from 7.8 +/- 0.6 to 4.4 +/- 0.5 cm/min (P < 0.0001). Phase III duration at each site was increased, and total recorded phase III was greater during imipramine than baseline studies. Imipramine increased the amplitude of phase III contractions. There was no effect of imipramine on non-phase-III motility index or discrete clustered contractions. Imipramine, prolonged OCTT from 73 +/- 6 min to 97 +/- 8 min in controls (P < 0.05) and from 61 +/- 9 min to 89 +/- 8 min in IBS (P < 0.05). Although OCTT was shorter in the IBS group, no motility differences were seen between controls and IBS. This demonstration that a tricylic antidepressant can modify small intestinal motor function in health and in IBS supports the view that these drugs may have therapeutic actions in IBS unrelated to mood improvement.

Influence of antidepressants on whole gut and orocaecal transit times in health and irritable bowel syndrome

BACKGROUND

Antidepressants are used in the treatment of irritable bowel syndrome but it is unclear whether any symptomatic improvement is due solely to correction of an associated affective disorder, or whether these drugs have effects on bowel function which may be of therapeutic benefit. Intestinal transit is known to be abnormal in some irritable bowel syndrome patients.

METHODS

We have studied the effects of imipramine, a tricyclic antidepressant with mixed pharmacological properties, and paroxetine, a selective 5-hydroxytryptamine re-uptake inhibitor, on intestinal transit times.

RESULTS

Median (range) whole gut transit time was lower in 10 diarrhoea-predominant irritable bowel syndrome patients, 22.2 (3.6-51.6) h, compared to 28 control subjects 39.6 (7.2-68.4) h, (P < 0.05). Similarly, orocaecal transit time was shorter at 55 (30-90) min in diarrhoea-predominant irritable bowel syndrome patients compared to 75 (40-150) min in controls, (P < 0.05). Four days' administration of imipramine increasing to a daily dose of 100 mg prolonged both orocaecal and whole gut transit times in 12 control subjects and six diarrhoea-predominant irritable bowel syndrome patients. In contrast, 30 mg paroxetine daily for 4 days reduced orocaecal transit time in ten controls and eight irritable bowel syndrome patients, but had no effect on whole gut transit time.

CONCLUSION

Short-term administration of antidepressants alters intestinal transit, but the selective 5-hydroxytryptamine re-uptake inhibitor, paroxetine, has different effects to the tricyclic drug, imipramine. These effects on transit precede any effects on mood. Although there is a high prevalence of affective disorder in irritable bowel syndrome clinic patients, these drugs may have additional therapeutic actions on the gut. These actions might be taken into account when prescribing antidepressants in irritable bowel syndrome.

Ambulatory small intestinal motility in 'diarrhoea' predominant irritable bowel syndrome

Dysmotility of the duodenum and proximal jejunum has been reported in patients with irritable bowel syndrome. This study extended these findings by recording fasting ambulatory motility from electronic strain gauge sensors sited in the jejunum and ileum of eight diarrhoea predominant irritable bowel syndrome patients and 12 healthy controls. During the day, periodicity of migrating motor complexes mean (SEM) did not differ between patients (92 (10) min) and controls (85 (7) min). At night, periodicity was shorter in both patients and controls, and the daytime dominance of phase II was replaced by phase I. In both groups, aboral progression of phase III fronts was associated with a slowing of propagation velocity and maximum contractile rate, but an increase in mean amplitude of contraction. Discrete clustered contractions were seen in seven patients and 10 controls occupying 14 and 16% of daytime phase II activity, respectively. Pain episodes were not associated with any specific motility patterns. Despite the lack of motility differences between the two groups, orocaecal transit time in the irritable bowel syndrome patients was shorter at 57 (9) min than in the controls, 82 (6) min (p < 0.05). This ambulant study has failed to show any abnormalities of fasting small intestinal motility that might distinguish diarrhoea predominant irritable bowel syndrome patients from healthy controls.

Loperamide. Survey of studies on mechanism of its antidiarrheal activity

In castor oil challenged rats, low doses of loperamide inhibit diarrhea and normalize intestinal propulsion. Unlike other opioids, loperamide is devoid of central opiate-like effects, including blockade of intestinal propulsion, up to the highest subtoxic oral dose. Nevertheless, the antidiarrheal action of loperamide can be considered to be mu-opiate receptor mediated, only a few in vitro effects at rather high concentrations being not naloxone-reversible. There is little evidence that interactions with intestinal opiate receptors directly change epithelial cell function. When secretory stimuli increase mucosal tension, however, loperamide may reverse the elevated hydrostatic tissue pressure that opposes normal absorption. This antisecretory effect at the mucosal level is accompanied by motor effects when loperamide reaches the myenteric mu-opiate receptors. At therapeutic doses for the treatment of acute diarrhea, it is likely that the mucosal effect prevails.

Orocaecal transit time in patients with Crohn disease

Orocaecal transit time (OCTT) using the lactulose hydrogen breath test was investigated in 16 patients (age 10-19.4 years) with active Crohn disease (CD). Disease activity was assessed by the paediatric CD activity index (PCDAI). OCTT was prolonged in all patients (mean 149.9 min, SD 32.7) relative to healthy age-matched controls (mean 56.9 min, SD 11.1). PCDAI was increased (median 48.8, range 32.5), indicating moderate to severe disease in all patients. A close correlation between OCTT and PCDAI (Spearman r = 0.90) was observed. Following nutritional therapy with a semi-elemental diet over a period of 6 weeks OCTT and PCDAI declined, OCTT becoming normal in 4 and PCDAI in 4/12 patients respectively. OCTT provides a sensitive, non-invasive method for the assessment and followup investigations in patients with CD.

Evidence for hypomotility in non-ulcer dyspepsia: a prospective multifactorial study

A prospective multifactorial study of symptoms and disturbance of gastrointestinal function has been undertaken in 50 patients with non-ulcer dyspepsia. Objective tests including solid meal gastric emptying studies, gastric acid secretion, E-HIDA scintiscan for enterogastric bile reflux, and hydrogen breath studies were carried out in all patients and validated against control data. Gastroscopy and biopsy were carried out in non-ulcer dyspepsia patients only. Non-ulcer dyspepsia patients were categorised on the basis of predominant symptoms as: dysmotility-like dyspepsia (n = 22); essential dyspepsia (n = 14), gastro-oesophageal reflux-like dyspepsia (n = 11); and ulcer-like dyspepsia (n = 3). In the total non-ulcer dyspepsia population, solid meal gastric emptying was delayed (T50 mean (SEM) = 102 (6) minutes (patients) v 64 (6) minutes (controls), (p less than 0.01) and high incidences of gastritis (n = 26) and Helicobacter pyloridis infection (n = 18) were found. An inverse correlation was observed between solid meal gastric emptying and fasting peak acid output (r = -0.4; p less than 0.01). Indeed gastric emptying was particularly prolonged in eight patients (T50 mean (SEM) = 139 (15) minutes) with hypochlorhydria. In the non-ulcer dyspepsia population oral to caecal transit time of a solid meal was delayed (mean SEM = 302 (14) minutes (patients) v 244 (12) minutes (controls) (p less than 0.01]. Seven patients had a dual peak of breath hydrogen suggestive of small bowel bacterial overgrowth. No association was observed between symptoms and any of the objective abnormalities. This multifactorial study has shown that hypomotility, including gastroparesis and delayed small bowel transit, is common in non-ulcer dyspepsia and may be related to other disorders of gastrointestinal function. No relation between symptoms and disorders of function, however, has been shown.

Effect of erythromycin on the oro-caecal transit time in man

Erythromycins often cause gastrointestinal side-effects due to an increase in motility or to change in the intestinal bacterial flora. In order to evaluate the effect of erythromycin on gastrointestinal motility. 11 healthy volunteers were given placebo, erythromycin stearate (ES) 1000 mg or a therapeutically equivalent single dose of erythromycin acistrate (EA.2'-acetyl erythromycin stearate) 800 mg in a double-blind trial. The oro-caecal transit time was measured using the hydrogen breath test with lactulose as the substrate. The transit time was estimated from the H2-peak (ppm) in end-expiratory breath by two methods, t1 representing the "front" and t2 the "bulk" of lactulose reaching the colon. t1 was 51 min in the placebo group, 38 min in the EA and 31 min in the ES group (p less than 0.05, ES vs placebo). t2 was 74 min, 64 min, and 46 min, respectively (p less than 0.05, ES vs placebo). The difference between EA and ES was also significant. Six subjects in the ES group but none in the EA group recorded adverse gastrointestinal effects attributable to medication. It was concluded that erythromycin shortens the oro-caecal transit time in man and that EA effects the transit time slightly less than ES.

Ileocolonic transfer of solid chyme in small intestinal neuropathies and myopathies

The aims of this study were to assess gastric emptying, small bowel transit and colonic filling in patients with motility disorders, with particular attention to the patterns of colonic filling. Gastrointestinal transit was assessed using a previously validated radiolabeled mixed meal. Fourteen patients with clinical and manometric features of chronic intestinal pseudoobstruction & classified as intestinal neuropathy and 6 as intestinal myopathy, were studied. The results were compared with those from 10 healthy controls studied similarly. Gastric emptying and small bowel transit of solids were significantly slower in both groups of patients than in healthy controls (P less than 0.05). In health, the ileocolonic transit of solid chyme was characterized by intermittent bolus transfers. The mean size of boluses transferred to the colon (expressed as a percentage of ingested radiolabel) was significantly less (P less than 0.05) in patients with intestinal myopathy (10% +/- 4% (SEM)] than in healthy controls (25% +/- 4%) or in patients with intestinal neuropathy (25% +/- 4%). The intervals between bolus transfer of solids (plateaus in the colonic filling curve) were longer (P less than 0.05) in myopathies (212 +/- 89 minutes) than in health (45 +/- 7 minutes) or neuropathies (53 +/- 11 minutes). Thus, gastric emptying and small bowel transit were delayed in small bowel neuropathies and myopathies. Bolus filling of the colon was less frequent and less effective in patients with myopathic intestinal pseudoobstruction, whereas bolus transfer was preserved in patients with neuropathic intestinal pseudoobstruction.

Breath hydrogen response to lactulose in healthy subjects: relationship to methane producing status

In order to assess the relationship between methane (CH4) producing status and the breath excretion of hydrogen (H2) in healthy subjects, breath CH4 and H2 were simultaneously measured for 14 hours after oral ingestion of 10 g lactulose in 65 young volunteers. Forty were breath CH4 producers and 25 were not. Statistically significant differences were observed between both groups, with lower values for CH4 producers recorded for the following parameters: fasting basal value of breath H2 (8.1 (4.9) v 5.2 (3.7) ppm, p less than 0.05), mouth-to-caecum transit time (68 (24) v 111 (52) min, p less than 0.005), and breath H2 production measured as area under the curve 13.1 (6.9) v 8.8 (3.8) 10(3) ppm/min, p less than 0.02). There was no significant correlation between individual production of breath H2 and CH4. These results indicate that the response to lactulose depends on breath CH4 producing status. In clinical practice, defining normal values of mouth-to-caecum transit time without knowledge of breath CH4 producing status may lead to misinterpretation of the H2 breath test.

Psychophysiologic responses to a realistic laboratory abdominal pain stimulus

Small doses of the carbohydrate lactulose are widely used in the clinical setting to assess small bowel transit time because lactulose is not absorbed by the small intestine and its arrival in the intestine can be detected non-invasively by breath hydrogen testing. In this study, doses of this safe, widely used substance higher than those typically administered for transit tests were given to 12 healthy young adult men to produce symptoms of gas and intestinal distention similar to those commonly experienced by patients with irritable bowel syndrome and recurrent abdominal pain. Comparison of subjective and physiological responses to the administration of 0 and 30 g of lactulose in a double-blind placebo-controlled trial demonstrated that the 30 g lactulose dose produced significant increases in a number of measures reflecting the intra-intestinal pain stimulus. The results of the present study indicate that lactulose is a realistic and ethically acceptable stimulus for the production of transient mild abdominal pain in the laboratory.

Effect of metoclopramide, bethanechol, and loperamide on gastric residence time, gastric emptying, and mouth-to-cecum transit time

The effects of metoclopramide, bethanechol, and loperamide on the gastric residence time (GRT), gastric emptying (GE), and mouth-to-cecum transit time (MCTT) of a solution were investigated in three separate studies of five healthy male volunteers each. Metoclopramide in doses of 5, 10, and 15 mg prolonged GRT by 33, 88, and 162%, respectively, almost reaching statistical significance (p 0.058). A relationship was observed between GRT prolongation, and metoclopramide area under the plasma-time curve (p 0.01) and metoclopramide observed time to maximum concentration (p 0.01). Metoclopramide had an inconsistent effect on MCTT. Bethanechol 50 mg prolonged GRT by 64% (p 0.031) and had no effect on MCTT. Loperamide at doses of 2 and 8 mg prolonged GRT by 18 and 115% (p 0.043) and MCTT by 30 and 130% (p 0.0001), respectively. None of these motility-altering agents affected GE.

Reproducible lactulose hydrogen breath test as a measure of mouth-to-cecum transit time

Breath hydrogen monitoring after oral lactulose syrup is a conventional measure of mouth-to-cecum transit time (MCTT), but its reproducibility has been questioned. We compared the reproducibility of five measurements of MCTT after a conventional breakfast (380 kcal) taken with tea containing 20 g lactulose to five measurements of MCTT after 20 g lactulose in water in eight normal volunteers. Individual mean breakfast transit time was not significantly different from lactulose transit time in each of the seven subjects, but one had a breakfast transit time of 151 +/- 15 min and a lactulose transit time of 86 +/- 22 minutes (X +/- SD, P less than 0.001). The coefficient of variation of breakfast transit time (11.6 +/- 5.3%, range: 6.9-24.2%) was less than that of lactulose transit time (30.7 +/- 7.8%, range: 22.1-50.0%, P less than 0.001). In a second set of experiments, the liquid phase marker (99mTechnetium-diethylene triamine pentaacetic acid) emptied from the stomach more rapidly after the lactulose solution (T1/2 16.3 +/- 5.4) than after the breakfast (33.9 +/- 10.9 min, P less than 0.01) and MCTT was shorter after lactulose (77 +/- 32 vs 104 +/- 40 min, respectively, P less than 0.05). There was no correlation between MCTT of lactulose and breakfast and between half-time gastric emptying and MCTT of either lactulose or breakfast. We conclude that the ingestion of inert lactulose induces an abnormally rapid MCTT and that breakfast MCTT is a much more reproducible investigation and should be employed in studies requiring serial measurements.

Orocaecal transit time in health and in thyroid disease

Altered bowel habit commonly occurs in thyroid disease. We measured orocaecal transit in healthy volunteers and in hyperthyroid and hypothyroid patients before and after treatment, using the lactulose hydrogen breath test incorporating a standard liquid meal to obtain a more physiological assessment. Mean transit time in 12 control subjects was 85 (8) minutes (mean (SE)) (mean coefficient of variation between replicate studies, 8.6% (3%)). In eighteen hyperthyroid patients transit was more rapid at 49 (4) minutes (p less than 0.01). Ten hypothyroid patients had a transit time similar to controls at 91 (9) minutes. Transit time returned to normal in thyrotoxic patients after treatment but in eight hypothyroid patients retested, it remained unchanged. Our findings suggest that (a) the inclusion of a liquid meal provides a reproducible method of measuring orocaecal transit using the lactulose hydrogen breath test, (b) rapid small bowel transit in thyrotoxicosis may be one factor in the diarrhoea which is a feature of the disease and (c) if altered gut transit is the cause of sluggish bowel habit in hypothyroidism, delay in the colon, and not small bowel, is likely to be responsible.

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.

The relation between bacterial degradation of viscous polysaccharides and stool output in human beings

1. The relation between bacterial degradation of three viscous polysaccharides (guar gum, ispaghula and xanthan gum) by colonic bacteria in vitro and their effects on colonic function were investigated by comparing the results of anaerobic in vitro incubations with fresh faeces from seven healthy volunteers (measuring viscosity, pH and gas production) with the effects of feeding all three polysaccharides to the same volunteers for 1 week each (14-15 g/d) on faecal mass and whole-gut transit time. 2. Guar gum was rapidly fermented in vitro by faecal bacteria from all volunteers with concomitant loss of viscosity, reduction in pH and generation of gases. Ispaghula maintained its viscosity during incubation, but the pH fell significantly. The results of xanthan gum incubations showed considerable individual variation. 3. Only ispaghula significantly increased faecal mass, whilst none of the gums significantly affected stool frequency or transit time. Statistical analysis of the pooled results showed that although transit time and faecal output were inversely related, feeding viscous polysaccharides could influence these indices independently. Stool frequency was significantly correlated with the transit time, but not the faecal output. 4. Transit time was reduced by gum feeding to a significantly greater extent in those subjects whose faecal bacteria reduced or removed the viscosity of that gum, than in those subjects where the viscosity was maintained. In contrast, there was a smaller increase in faecal mass when the viscosity of the appropriate cultures was removed than when it was maintained or reduced. Increases in stool frequency were significantly associated with hydrogen production from in vitro cultures.

Impaired colonic fermentation of carbohydrate after ampicillin

The aim of this study was to investigate the effect of ampicillin on the ability of the human colon to ferment carbohydrate. The effect of ingesting a drink containing 20 g of lactulose on stool output and breath hydrogen production was measured in 13 normal volunteers before and during administration of ampicillin (2 g/day). Small bowel and whole gut transit times were also measured to exclude any direct effect of ampicillin on motor activity. Ingestion of lactulose did not increase stool weight or frequency under control conditions, but during administration of ampicillin, lactulose caused increases in stool weight (p less than 0.02) and frequency (p less than 0.01), in the percentage of unformed stools (p less than 0.001), and in the excretion of galactose and fructose in stool samples collected from 2 volunteers. Administration of ampicillin also significantly reduced the area under the breath hydrogen profile (p less than 0.03). Mouth-to-cecum transit of the lactulose drink was prolonged during ampicillin ingestion (p less than 0.01) but there was no significant change in the whole gut transit time. These results suggest that ampicillin impairs colonic fermentation of carbohydrate and a diet high in unabsorbable carbohydrate increases the risk of antibiotic-associated diarrhea.

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.

Modulation of human upper gastrointestinal motility by rectal distension

The effects of rectal distension on upper gastrointestinal motility were investigated in six healthy subjects. On a control day, gastric and duodenal motor activity was recorded for nine hours of fasting and for four hours after a meal, duodeno-caecal transit being assessed in both interdigestive and digestive states. Motor activity and transit were also measured on a test day during which the rectum was distended for one hour during fasting and for one hour postprandially. Control and test days were randomised. During fasting, rectal distension increased the incidence of migrating motor complexes (0.8 +/- 0.3 v 0.5 +/- 0.2 h; p less than 0.01) and reduced the duodenal phase 2 motility index to 66 +/- 45% of that observed on the control day (p less than 0.01). Further, duodeno-caecal transit time was increased by rectal distension (99 +/- 30 v 71 +/- 35 min; p less than 0.05). Postprandially, the period of rectal distension was marked by a reduction in the duodenal motility index to 24 +/- 13% of that observed during the comparable period on the control day (p less than 0.001) and a concomitant increase in duodeno-caecal transit time (113 +/- 22 v 80 +/- 17 min; p less than 0.01). We conclude that upper gastrointestinal motor activity, the effector of luminal transit, may be profoundly influenced by stimulation of distal afferents.

Limitations of indirect methods of estimating small bowel transit in man

Experiments were carried out in healthy volunteers to explore the utility of a new [14C]lactulose breath test for measuring small intestinal transit time in man and to use this procedure to test whether two antidiarrheal agents, codeine and clonidine, alter small intestinal transit time during digestion of a liquid meal. In an initial validation study performed in 12 subjects (three studies in each subject), a liquid test meal containing 10 g [14C]lactulose was administered and the colonic entry time estimated from the time course of 14CO2 excretion in breath compared with that of H2 excretion. There was a fair correlation (r = 0.77; P less than 0.001) between results obtained by the two methods; both methods gave similar results, but 14CO2 output was delayed when compared to H2 output and was incomplete. The meal also contained xylose and [13C]glycine, permitting the duodenal entry time of the meal to be estimated by the appearance of xylose in blood and 13CO2 in breath, respectively. The same liquid meal was then used to examine the effect on small intestinal transit time (colonic entry time minus duodenal entry time) of codeine or clonidine. 99Tc-sulphur colloid was also added to the meal to permit a comparison of small intestinal transit estimated by imaging with that estimated by the 14CO2-lactulose breath test. 99Tc radioactivity appeared in the cecum (as assessed using gamma scintigraphy) about 2 hr before 14CO2 radioactivity appeared in breath; the correlation between transit time estimated by the two methods was moderate (r = 0.61; P less than 0.05). Based on the [14C]lactulose data, small intestinal transit time ranged from less than 1 to 3 hr for a liquid meal containing 10 g lactulose; within-subject variation (coefficient of variation 17%) was considerably less than between-subject variation (coefficient of variation 56%). Codeine increased the small intestinal transit time significantly (from 2.7 +/- 0.3 hr to 5.0 +/- 0.9 hr; mean +/- SE), whereas clonidine did not alter small intestinal transit time, as estimated by the colonic entry time minus duodenal entry time. Neither drug influenced duodenal entry time. These results suggest that the [14C]lactulose breath test, which has only moderate accuracy, may have occasional utility as a convenient, noninvasive method for estimating small intestinal transit time in man. However, this study also suggests that indirect methods of estimating small bowel transit in man have limitations, variability, and possibly may lack the desired sensitivity.

Seeking clues for a positive diagnosis of the irritable bowel syndrome

Despite its high prevalence the irritable bowel syndrome (IBS) lacks acceptable pathophysiological markers and its diagnosis largely depends on the exclusion of underlying organic disease. Systemic acid-base balance, serum electrolytes and the composition of faecal water (electrolytes and organic anions), were studied in thirty-eight diarrhoeal patients out of a series of ninety-three consecutive IBS patients. Only patients with diarrhoea as the predominant symptom were included in the study to evaluate whether this subgroup could provide the clue for a positive diagnosis of the syndrome. Serum electrolytes and systemic acid-base balance were within the normal range. Faecal electrolytes were also normal (Na 26.6 +/- 19.3 SD; K 66.8 +/- 28.3; Cl 19.1 +/- 15.2 mEq 1(-1)), despite the finding of a moderately increased 24-h faecal output. The K:Na ratio was also within the normal range. These data are in agreement with the lack of systemic changes observed in IBS patients even with profuse or longstanding diarrhoea. Both faecal short chain fatty acids and lactic acid were increased in patients vs. controls, but a considerable overlap with normal values was observed (131.4 +/- 62.6 SD vs. 108.5 +/- 58.3 mEq 1(-1). Only lactic acid concentration was significantly higher than in controls (1.3 +/- 1.2 vs. 0.5 +/- 0.2). Despite these findings it is concluded that the subgroup of IBS patients with diarrhoea also appears to lack a pathophysiological marker and does not provide clues for a positive diagnosis of this syndrome.

Effects of peptide YY (PYY) on mouth to caecum intestinal transit time and on the rate of gastric emptying in healthy volunteers

The effect of an infusion of two doses of peptide YY (PYY), a novel putative gastrointestinal hormone, has been assessed on mouth to caecum intestinal transit time and on the rate of gastric emptying after ingestion of an inert 200 ml liquid meal thought unlikely to interrupt fasting gastrointestinal motility patterns. A low dose of PYY was chosen to give plasma concentrations within the range seen postprandially in healthy subjects, while the high dose mimicked the raised levels seen in several malabsorptive conditions. During infusion of PYY at 0.18 pmol/kg/min plasma concentrations rose from a basal of 8 +/- 2 pmol/l to 38 +/- 5 pmol/l and at 0.51 pmol/kg/min to 87 +/- 10 pmol/l. Mouth to caecum transit time was delayed from 67 +/- 4 mins on the saline infusion day to 94 +/- 7 mins (p less than 0.01) on the low dose and 192 +/- 9 mins (p less than 0.001) on the high dose infusion day. Time to 50% gastric emptying was prolonged from 37 +/- 8 mins during saline infusion to 63 +/- 10 mins (p less than 0.05) during low and 130 +/- 12 mins (p less than 0.001) during high dose infusion. Thus the infusion of PYY shows a dose related inhibition of mouth to caecum intestinal transit time and of the rate of gastric emptying and suggests this novel hormonal peptide to be of importance in gastrointestinal physiology.

Gastric emptying rate and small bowel transit time in patients with irritable bowel syndrome determined with 99mTc-labeled pellets and scintigraphy

A new method employing 99mTc-labeled pellets for determination of the gastric emptying rate and small bowel transit time is described. The participants were six normal subjects and 16 patients with irritable bowel syndrome (eight with diarrhea and eight with obstipation as the primary complaint). The gastric emptying rate was the same in the three groups. The patients in the obstipation group had a significantly longer small bowel transit time than the normals (P less than 0.02) and the patients in the diarrhea group (P less than 0.01). There was no demonstrable difference between the small bowel transit time in the normals and in the patients in the diarrhea group.

Influence of the oropharyngeal microflora on the measurement of exhaled breath hydrogen

We investigated the possible contribution made by oropharyngeal microfloral fermentation of ingested carbohydrate to the generation of the early, transient exhaled breath hydrogen rise seen after carbohydrate ingestion. Ten subjects ate or were sham fed carbohydrate-containing meals with and without prior chlorhexidine mouthwash during serial collection of exhaled breath and mouth hydrogen samples. Meal ingestion and sham feeding both induced significant (p less than 0.01) elevations of breath and mouth hydrogen that were virtually abolished by prior chlorhexidine mouthwash. In 7 subjects, delivery of the meal directly into the stomach via an orogastric tube did not cause a breath or mouth hydrogen rise. Oral contents incubated anaerobically in vitro with carbohydrate generated hydrogen that was again inhibited by chlorhexidine. These studies indicate that fermentation of ingested carbohydrate by oropharyngeal bacteria can contribute significantly to measured breath hydrogen values soon after meal ingestion, and may introduce avoidable error into the interpretation of serial breath hydrogen data.