Mechanisms underlying the laxative effect of lactulose: A randomized placebo-controlled trial showing increased small bowel water and motility unaltered by the 5-HT3 receptor antagonist, ondansetron

BACKGROUND

Lactulose is a laxative which accelerates transit and softens stool. Our aim was to investigate its mechanism of action and use this model of diarrhea to investigate the anti-diarrheal actions of ondansetron.

METHODS

A double-blind, randomized, placebo-controlled crossover study of the effect of ondansetron 8 mg in 16 healthy volunteers. Serial MRI scans were performed fasted and 6 h after a meal. Participants then received lactulose 13.6 g twice daily and study drug for a further 36 h. On Day 3, they had further serial MRI scans for 4 h. Measurements included small bowel water content (SBWC), colonic volume, colonic gas, small bowel motility, whole gut transit, and ascending colon relaxation time (T1AC), a measure of colonic water content.

KEY RESULTS

Lactulose increased area under the curve (AUC) of SBWC from 0 to 240 min, mean difference 14.2 L · min (95% CI 4.1, 24.3), p = 0.009, and substantially increased small bowel motility after 4 h (mean (95% CI) 523 (457-646) a.u. to 852 (771-1178) a.u., p = 0.007). There were no changes in T1AC after 36 h treatment. Ondansetron did not significantly alter SBWC, small bowel motility, transit, colonic volumes, colonic gas nor T1AC, with or without lactulose.

CONCLUSION & INFERENCES

Lactulose increases SBWC and stimulates small bowel motility; however, unexpectedly it did not significantly alter colonic water content, suggesting its laxative effect is not osmotic but due to stimulation of motility. Ondansetron's lack of effect on intestinal water suggests its anti-diarrheal effect is not due to inhibition of secretion but more likely altered colonic motility.

Demonstration of differences in colonic volumes, transit, chyme consistency, and response to psyllium between healthy and constipated subjects using magnetic resonance imaging

BACKGROUND

In functional gastrointestinal disorders a lack of objective biomarkers limits evaluation of underlying mechanisms. We aimed to demonstrate the utility of magnetic resonance imaging for this task using psyllium, an effective constipation treatment, in patients and controls.

METHODS

Two crossover studies: (i) adults without constipation (controls, n = 9) took three treatments in randomized order for 6 days - maltodextrin (placebo), psyllium 3.5 g t.d.s and 7 g t.d.s., (ii) adults with chronic constipation (patients, n = 20) took placebo and psyllium 7 g t.d.s. for 6 days. MRI was performed fasting and postprandially on day 6. Measurements included small bowel and ascending colon water content, colonic volume, transit time, and MR relaxometry (T1, T2) to assess colonic chyme. Stool water percentage was measured.

RESULTS

7 g psyllium t.d.s. increased fasting colonic volumes in controls from median 372 mL (IQR 284-601) to 578 mL (IQR 510-882), and in patients from median 831 mL (IQR 745-934) to 1104 mL (847-1316), P < .05. Mean postprandial small bowel water was higher in controls and patients after 7 g psyllium t.d.s. vs placebo. Whole gut transit was slower in patients than controls (P < .05). T1 of the descending colon chyme (fasting) was lower in patients (213 ms, 176-420) than controls (440 ms, 352-884, P < .05) on placebo, but increased by 7 g psyllium t.d.s. (590 ms, 446-1338), P < .001. Descending colon T1 correlated with baseline stool water content and stool frequency on treatment.

CONCLUSIONS AND INFERENCES

MRI measurements can objectively demonstrate the mode of action of therapy targeting intestinal fluid content in constipation.

Randomised clinical trial: mesalazine versus placebo in the prevention of diverticulitis recurrence

BACKGROUND

Previous studies have reached conflicting conclusions regarding the efficacy of mesalazine in the prevention of recurrent diverticulitis.

AIM

To investigate the efficacy and safety of mesalazine granules in the prevention of recurrence of diverticulitis after acute uncomplicated diverticulitis.

METHODS

Two phase 3, randomised, placebo-controlled, double-blind multicentre trials (SAG-37 and SAG-51) investigated mesalazine granules in patients with prior episodes (<6 months) of uncomplicated left-sided diverticulitis. Patients were randomised to receive either 3 g mesalazine once daily or placebo (SAG-37, n=345) or to receive either 1.5 g mesalazine once daily, 3 g once daily or placebo for 96 weeks (SAG-51, n=330). The primary endpoint was the proportion of recurrence-free patients during 48 weeks (SAG-37 and SAG-51) or 96 weeks (SAG-51) of treatment.

RESULTS

Mesalazine did not increase the proportion of recurrence-free patients over 48 or 96 weeks compared to placebo. In SAG-37, the proportion of recurrence-free patients during 48 weeks was 67.9% with mesalazine and 74.4% with placebo (P=.226). In SAG-51, the proportion of recurrence-free patients over 48 weeks was 46.0% with 1.5 g mesalazine, 52.0% with 3 g mesalazine and 58.0% with placebo (P=.860 for 3 g mesalazine vs placebo) and over 96 weeks 6.9%, 9.8% and 23.1% respectively (P=.980 for 3 g mesalazine vs placebo). Patients with only one diverticulitis episode in the year prior to study entry had a lower recurrence risk compared to >1 episode. Safety data revealed no new adverse events.

CONCLUSION

Mesalazine was not superior to placebo in preventing recurrence of diverticulitis.

Colonic response to laxative ingestion as assessed by MRI differs in constipated irritable bowel syndrome compared to functional constipation

BACKGROUND

Functional constipation (FC) and irritable bowel syndrome with constipation (IBS-C) share many symptoms but underlying mechanisms may be different. We have developed a magnetic resonance imaging (MRI) technique to measure intestinal volumes, transit, and motility in response to a laxative, Moviprep(®) . We aim to use these biomarkers to study the pathophysiology in IBS-C and FC.

METHODS

Twenty-four FC and 24 IBS-C were studied. Transit was assessed using the weighted average position score (WAPS) of five MRI marker pills, taken 24 h before MRI scanning. Following baseline scan, participants ingested 1 L of Moviprep(®) followed by hourly scans. Magnetic resonance imaging parameters and bowel symptoms were scored from 0 to 4 h.

KEY RESULTS

Weighted average position score for FC was 3.6 (2.5-4.2), significantly greater than IBS-C at 2.0 (1.5-3.2), p = 0.01, indicating slower transit for FC. Functional constipation showed greater fasting small bowel water content, 83 (63-142) mL vs 39 (15-70) mL in IBS-C, p < 0.01 and greater ascending colon volume (AC), 314 (101) mL vs 226 (71) mL in IBS-C, p < 0.01. FC motility index was lower at 0.055 (0.044) compared to IBS-C, 0.107 (0.070), p < 0.01. Time to first bowel movement following ingestion of Moviprep(®) was greater for FC, being 295 (116-526) min, compared to IBS-C at 84 (49-111) min, p < 0.01, and correlated with AC volume 2 h after Moviprep(®) , r = 0.44, p < 0.01. Using a cut-off >230 min distinguishes FC from IBS-C with low sensitivity of 55% but high specificity of 95%.

CONCLUSION & INFERENCES

Our objective MRI biomarkers allow a distinction between FC and IBS-C.

A meta-analysis of immunogenetic Case-Control Association Studies in irritable bowel syndrome

BACKGROUND

To date, genetic-association studies of single nucleotide polymorphisms (SNP) in selected candidate genes with the symptom phenotype of irritable bowel syndrome (IBS) have typically involved hundreds to 2000 patients. SNPs in immune-related genes, such as cytokine and cytokine receptor encoding genes, have been reported to associate with IBS risk.

METHODS

We conducted two independent case-control studies on 16 SNPs in IL1R1, IL4, IL6, IL8, IL10, IL23R, TNFA, and TNFSF15, one from the UK (194 patients and 92 healthy volunteers) and one from the USA (137 patients and 96 healthy volunteers). The main aim was to examine the relationship between inherited immunological diversity and IBS risk in a meta-analysis which included 12 additional, earlier studies. The meta-analysis comprised a total of 2894 patients (839 IBS-C, 1073 IBS-D, 502 IBS-M), and 3138 healthy volunteers with self-reported Caucasian ancestry.

KEY RESULTS

The association of SNP rs4263839 (TNFSF15) was investigated in four studies and confirmed in the meta-analysis: IBS (OR 1.19, 95% CI 1.08-1.31), and IBS-C (OR 1.24, 95% CI 1.08-1.42). No additional SNPs residing in immunogenes associated with IBS symptom phenotypes.

CONCLUSIONS & INFERENCES

Our meta-analysis could not confirm a major role of most investigated SNPs, but a moderate association between rs4263839 TNFSF15 and IBS, in particular IBS-C. The analysis emphasizes the importance of definition and phenotype homogeneity, adequate study size and representativeness of the patient and control collective.

Relative importance of abnormalities of CCK and 5-HT (serotonin) in Giardia-induced post-infectious irritable bowel syndrome and functional dyspepsia

BACKGROUND

Post-infectious irritable bowel syndrome (PI-IBS) and functional dyspepsia (FD) have been described after both Campylobacter jejuni gastroenteritis and Giardia infection. After C. jejuni, there is increased rectal serotonin (5-HT)-containing EC cells and postprandial plasma 5-HT, while a pilot study suggested increased plasma cholecystokinin (CCK) after Giardia infection.

AIM

To determine changes in plasma and duodenal mucosal 5-HT and CCK in Giardia-induced PI-IBS.

METHODS

A total of 32 patients previously infected with Giardia and 19 who had recovered fully (controls) completed symptom questionnaires. Endoscopic duodenal biopsies were obtained from all subjects and immunohistochemically stained for CCK, 5-HT and CgA containing entero-endocrine cells and mast cells. 5-HT content was also assessed. Twenty-one of 32 patients and 19 controls consumed a high-carbohydrate meal, while fasting and postprandial plasma CCK and 5-HIAA were measured.

RESULTS

Post-infectious irritable bowel syndrome patients had increased numbers of CCK cells (P = 0.02), but lower numbers of EC cells (P = 0.009). Plasma CCK did not differ significantly between the groups, but correlated significantly with postprandial dyspepsia scores (r = 0.5, P = 0.05). PI-IBS patients had significantly lower plasma 5-HIAA, before and after meal (P = 0.05) as well as more dyspepsia (P < 0.0001) compared with recovered subjects.

CONCLUSIONS

Post-infectious bowel dysfunction following Giardia infection is associated with increased duodenal mucosal CCK. Postprandial dyspeptic symptoms correlate better with CCK than measures of 5-HT metabolism.

Gastroparesis and functional dyspepsia: excerpts from the AGA/ANMS meeting

BACKGROUND

Despite the relatively high prevalence of gastroparesis and functional dyspepsia, the aetiology and pathophysiology of these disorders remain incompletely understood. Similarly, the diagnostic and treatment options for these two disorders are relatively limited despite recent advances in our understanding of both disorders.

PURPOSE

This manuscript reviews the advances in the understanding of the epidemiology, pathophysiology, diagnosis, and treatment of gastroparesis and functional dyspepsia as discussed at a recent conference sponsored by the American Gastroenterological Association (AGA) and the American Neurogastroenterology and Motility Society (ANMS). Particular focus is placed on discussing unmet needs and areas for future research.

Review article: probiotics and prebiotics in irritable bowel syndrome

BACKGROUND

The human gut harbours a complex community of bacteria whose relationship with their host is normally mutually beneficial. Recent studies suggest a disturbance of this relationship in irritable bowel syndrome (IBS) and the potential to correct this using prebiotics and probiotics.

AIM

To review the mechanisms of action of probiotics and prebiotics in IBS and to assess their performance in clinical trials.

METHODS

Articles relating to modes of action and randomized control trials of treatment were reviewed by searching PubMed using terms 'probiotic', 'prebiotic' and 'irritable bowel'. Small uncontrolled studies in IBS were excluded.

RESULTS

Probiotics can enhance gut barrier function, inhibit pathogen binding and modulate gut inflammatory response. They can also reduce visceral hypersensitivity associated with both inflammation and psychological stress. Probiotics can alter colonic fermentation and stabilize the colonic microbiota. Several large randomized, placebo-controlled trials of adequate design have shown an improvement in flatulence and abdominal distension with a reduction in composite IBS symptoms scores.

CONCLUSIONS

Each probiotic has unique features and IBS patients are heterogeneous. Future efforts should be directed to identifying biomarkers of responsiveness to facilitate better targeting of treatment and hence improved efficacy.

Gut in 2007

Editor's report for past year

Guidelines on the irritable bowel syndrome: mechanisms and practical management

BACKGROUND

IBS affects 5-11% of the population of most countries. Prevalence peaks in the third and fourth decades, with a female predominance.

AIM

To provide a guide for the assessment and management of adult patients with irritable bowel syndrome.

METHODS

Members of the Clinical Services Committee of The British Society of Gastroenterology were allocated particular areas to produce review documents. Literature searching included systematic searches using electronic databases such as Pubmed, EMBASE, MEDLINE, Web of Science, and Cochrane databases and extensive personal reference databases.

RESULTS

Patients can usefully be classified by predominant bowel habit. Few investigations are needed except when diarrhoea is a prominent feature. Alarm features may warrant further investigation. Adverse psychological features and somatisation are often present. Ascertaining the patients' concerns and explaining symptoms in simple terms improves outcome. IBS is a heterogeneous condition with a range of treatments, each of which benefits a small proportion of patients. Treatment of associated anxiety and depression often improves bowel and other symptoms. Randomised placebo controlled trials show benefit as follows: cognitive behavioural therapy and psychodynamic interpersonal therapy improve coping; hypnotherapy benefits global symptoms in otherwise refractory patients; antispasmodics and tricyclic antidepressants improve pain; ispaghula improves pain and bowel habit; 5-HT(3) antagonists improve global symptoms, diarrhoea, and pain but may rarely cause unexplained colitis; 5-HT(4) agonists improve global symptoms, constipation, and bloating; selective serotonin reuptake inhibitors improve global symptoms.

CONCLUSIONS

Better ways of identifying which patients will respond to specific treatments are urgently needed.

Guidelines on the irritable bowel syndrome: mechanisms and practical management

BACKGROUND

IBS affects 5-11% of the population of most countries. Prevalence peaks in the third and fourth decades, with a female predominance.

AIM

To provide a guide for the assessment and management of adult patients with irritable bowel syndrome.

METHODS

Members of the Clinical Services Committee of The British Society of Gastroenterology were allocated particular areas to produce review documents. Literature searching included systematic searches using electronic databases such as Pubmed, EMBASE, MEDLINE, Web of Science, and Cochrane databases and extensive personal reference databases.

RESULTS

Patients can usefully be classified by predominant bowel habit. Few investigations are needed except when diarrhoea is a prominent feature. Alarm features may warrant further investigation. Adverse psychological features and somatisation are often present. Ascertaining the patients' concerns and explaining symptoms in simple terms improves outcome. IBS is a heterogeneous condition with a range of treatments, each of which benefits a small proportion of patients. Treatment of associated anxiety and depression often improves bowel and other symptoms. Randomised placebo controlled trials show benefit as follows: cognitive behavioural therapy and psychodynamic interpersonal therapy improve coping; hypnotherapy benefits global symptoms in otherwise refractory patients; antispasmodics and tricyclic antidepressants improve pain; ispaghula improves pain and bowel habit; 5-HT(3) antagonists improve global symptoms, diarrhoea, and pain but may rarely cause unexplained colitis; 5-HT(4) agonists improve global symptoms, constipation, and bloating; selective serotonin reuptake inhibitors improve global symptoms.

CONCLUSIONS

Better ways of identifying which patients will respond to specific treatments are urgently needed.

Recent advances in understanding the role of serotonin in gastrointestinal motility in functional bowel disorders: alterations in 5-HT signalling and metabolism in human disease

Serotonin (5-hydroxytryptamine, 5-HT) is present in abundance within the gut, most stored in enterochromaffin cell granules. It is released by a range of stimuli, most potently by mucosal stroking. Released 5-HT stimulates local enteric nervous reflexes to initiate secretion and propulsive motility. It also acts on vagal afferents altering motility and in large amounts induces nausea. Rapid reuptake by a specific transporter (serotonin transporter, SERT) limits its diffusion and actions. Abnormally increased 5-HT is found in a range of gastrointestinal disorders including chemotherapy-induced nausea and vomiting, carcinoid syndrome, coeliac disease, inflammatory bowel disease and irritable bowel syndrome (IBS) with diarrhoea (IBS-D), especially that developing following enteric infection. Impaired SERT has been described in IBS-D and might account for some of the increase in mucosal 5-HT availability. 5-HT(3) receptor antagonists inhibit chemotherapy-induced nausea and diarrhoea associated with both carcinoid syndrome and IBS. While IBS-D is associated with increased 5-HT postprandially, IBS with constipation (IBS-C) is associated with impaired 5-HT response and responds to 5-HT(4) agonists such as Prucalopride and 5-HT(4) partial agonists such as Tegaserod.

Role of motility in chronic diarrhoea

Patients complaining of 'chronic diarrhoea' usually mean the passage of loose, urgent stools. Chronic diarrhoea is a feature of malabsorption; it may also be seen in the 'dumping syndrome' which follows gastric surgery, small intestinal bacterial overgrowth, bile salt malabsorption and in malabsorption of simple sugars including most commonly lactose, fructose and sorbitol. Excessively rapid entry of chyme into the small or large intestine generates propulsive motor patterns leading to accelerated transit. Inflammation is associated with decreased normal mixing motor patterns but increased propulsive motility including high amplitude propagated contractions (HAPCs). Evidence for abnormal small intestinal motility in the diarrhoea associated with irritable bowel syndrome (IBS) is conflicting and any difference appears small. Increased colonic HAPCs with increased propulsion is seen in IBS with diarrhoea (IBS-D). Stress-induced colonic motility is increased in IBS-D with hyper-responsiveness to corticotrophin releasing factor (CRF). Long-lasting increases in mucosal serotonin availability may contribute to the chronic diarrhoea seen in IBS-D and coeliac disease. Treatments for abnormal motility in chronic diarrhoea include those designed to correct specific underlying abnormalities including octreotide, antibiotics, colestyramine, specific food avoidance and anti-inflammatory agents. There are also treatments aimed primarily at altering motility directly including opiates, 5HT3 receptor antagonists and amitriptyline.

Enterochromaffin cell hyperplasia and decreased serotonin transporter in a mouse model of postinfectious bowel dysfunction

Patients with postinfective irritable bowel syndrome and Trichinella spiralis-infected mice share many features including visceral hypersensitivity and disordered motility. We assessed enterochromaffin (EC) numbers and serotonin transporter (SERT) using National Institute of Health (NIH) female mice studied for up to 56 days post-T. spiralis infection. The effects of steroid treatment and the T-cell dependence of the observed responses were assessed by infection of hydrocortisone-treated or T-cell receptor knock out [TCR (betaxdelta) KO] animals. Enterochromaffin cell density in uninfected animals increased from duodenum 10.0 cells mm-2 (5.9-41.0) to colon 61.8. (46.3-162) cells mm-2 P<0.0001. Infection increased duodenal and jejunal counts which rose to 37.3 (22-57.7) cells mm-2 and 50.6 (7-110.8) cells mm-2, respectively, at day 14. Infection significantly reduced jejunal SERT expression, with luminance values falling from 61.0 (45.1-98.3) to a nadir of 11.6 (0-36.0) units at day 9, P<0.001. Specific deficiencies in all T cells reduced EC hyperplasia and abrogated infection-induced mastocytosis. Thus infection induced inflammation increases EC numbers, as has been reported in PI-IBS, and reduces SERT. This may increase mucosal 5HT availability and contribute to the clinical presentation of PI-IBS.

Pharmacotherapy: non-serotonergic mechanisms

Antidepressants rapidly relieve pain in irritable bowel syndrome (IBS) and are effective at low doses. Noradrenaline reuptake inhibitors appear to be more effective than selective serotonergic reuptake inhibitors, suggesting that pathways other than those modulated by serotonin may be involved in visceral sensation. Visceral sensitivity is reduced by both centrally and peripherally acting opioids, suggesting the possible existence of an endogenous opioid deficiency in patients with IBS. The alpha(2) adrenoceptor antagonist clonidine, as well as somatostatin, oxytocin, and possibly amitriptyline have also been shown to act as visceral analgesics. As knowledge increases, there are undoubtedly many other possible targets, and new drugs currently undergoing development may provide future benefit in patients with IBS.

Antimicrobial susceptibility testing of Helicobacter pylori in a large multicenter trial: the MACH 2 study

Culture and susceptibility testing of Helicobacter pylori strains was performed in a large multinational, multicenter randomized clinical trial. Culture was carried out on gastric biopsy samples obtained from 516 patients at entry and had a sensitivity of 99% when the [(13)C]urea breath test was used as a reference. Susceptibility testing was performed for clarithromycin and metronidazole on 485 strains by an agar dilution method and the epsilometer test (Etest) and for amoxicillin by an agar dilution method only. Resistance to clarithromycin (>1 microgram/ml) was found in 3% of the H. pylori strains, with a perfect correlation between Etest and agar dilution methods. Resistance to metronidazole (>8 microliter/ml) was found in 27% of the strains by agar dilution, but there were important discrepancies between it and the Etest method. No resistance to amoxicillin was found. The logarithms of the MICs of the three antibiotics against susceptible strains had a distribution close to normal. The impact of resistance was tested in the four arms of the trial. There were not enough clarithromycin-resistant strains to evaluate the impact of resistance on the cure rate of clarithromycin-based regimens. For metronidazole-resistant strains, the impact noted in the clarithromycin-metronidazole arm was partially overcome when omeprazole was added (76% eradication for resistant strains versus 95% for susceptible strains). Secondary resistance to clarithromycin occurred in strains from 12 of 105 patients (11.4%) after the failure of a clarithromycin-based regimen to effect eradication. The detection of point mutations in clarithromycin-resistant strains was performed by a combination of PCR and restriction fragment length polymorphism. Mutations (A2142G and 2143G) were found in all strains tested except one. This study stresses the importance of performing susceptibility tests in clinical trials in order to explain the results of different treatments.

Omeprazole, amoxycillin and metronidazole for the cure of Helicobacter pylori infection

OBJECTIVE

In two studies, different regimens of omeprazole-amoxycillin-metronidazole were assessed for the eradication of Helicobacter pylori.

DESIGN

Randomized, international, multicentre studies with parallel groups.

SETTING

The studies were performed at centres in Canada, Czech Republic, France, Germany, Hungary, Sweden and UK.

PARTICIPANTS AND INTERVENTIONS

H. pylori-positive patients with duodenal ulcer disease (active or in remission) were randomized to 7-day treatment with: omeprazole 40 mg once daily, amoxycillin 500 mg three times daily and metronidazole 400 mg three times daily (OAMtid; n = 242); omeprazole 20 mg twice daily, amoxycillin 1000 mg twice daily and metronidazole 800 mg twice daily (OAM800; n = 247); or omeprazole 20 mg twice daily, amoxycillin 1000 mg twice daily and metronidazole 400 mg twice daily (OAM400; n = 127).

MAIN OUTCOME MEASURES

Eradication of H. pylori.

RESULTS

Intention-to-treat analysis revealed H. pylori eradication rates of 76% (184/242) with OAMtid, 80% (198/247) with OAM800, and 76% (97/127) with OAM400. There was considerable variation in the levels of primary resistance to metronidazole in different countries. The overall eradication rate in patients infected with metronidazole-sensitive H. pylori strains was 85% (313/370), compared with 60% (56/94) in patients harbouring metronidazole-resistant strains (P<0.001). All regimens were generally well tolerated, with mild adverse events occurring in 4-26% of patients (mainly diarrhoea, reversible increase in liver enzymes and headache).

CONCLUSION

The OAM combination is effective in curing H. pylori infection. Primary metronidazole resistance may reduce its effectiveness, but an increased daily dosing of metronidazole may partly overcome this problem.

The MACH2 study: role of omeprazole in eradication of Helicobacter pylori with 1-week triple therapies

BACKGROUND & AIMS

The role of omeprazole in triple therapy and the impact of Helicobacter pylori resistance on treatment outcome are not established. This study investigated the role of omeprazole and influence of primary H. pylori resistance on eradication and development of secondary resistance.

METHODS

Patients (n = 539) with a history of duodenal ulcer and a positive H. pylori screening test result were randomized into 4 groups. OAC group received 20 mg omeprazole, 1000 mg amoxicillin, and 500 mg clarithromycin; OMC group received 20 mg omeprazole, 400 mg metronidazole, and 250 mg clarithromycin; and AC (amoxicillin, 1000 mg, and clarithromycin, 500 mg) and MC (metronidazole, 400 mg, and clarithromycin, 250 mg) groups received no omeprazole. All doses were administered twice daily for 1 week. H. pylori status was assessed before and after therapy by 13C-urea breath test. Susceptibility testing was performed at entry and in patients with persistent infection after therapy.

RESULTS

Eradication (intention to treat [n = 514]/per protocol [n = 449]) was 94%/95% for OAC, 26%/25% for AC (P < 0.001), 87%/91% for OMC, and 69%/72% for MC (P < 0.001). Primary resistance was 27% for metronidazole, 3% for clarithromycin, and 0% for amoxicillin. Eradication in primary metronidazole-susceptible/-resistant strains was 95%/76% for OMC and 86%/43% for MC. Secondary metronidazole and clarithromycin resistance each developed in 12 patients: 8 treated with omeprazole and 16 without omeprazole.

CONCLUSIONS

Addition of omeprazole achieves high eradication rates, reduces the impact of primary resistance, and may decrease the risk of secondary resistance compared with regimens containing only two antibiotics.

Prevalence of gastrointestinal symptoms six months after bacterial gastroenteritis and risk factors for development of the irritable bowel syndrome: postal survey of patients

OBJECTIVE

To measure the prevalence of gastrointestinal symptoms six months after bacterial gastroenteritis and determine risk factors and associations with postdysenteric symptoms.

DESIGN

Postal questionnaire.

SETTING

Nottingham Health Authority.

SUBJECTS

544 people with microbiologically confirmed bacterial gastroenteritis between July 1994 and December 1994.

MAIN OUTCOME MEASURES

Prevalence of gastrointestinal symptoms and relative risks for development of the irritable bowel syndrome and self reported altered bowel habit.

RESULTS

A quarter of subjects reported persistence of altered bowel habit six months after an episode of infective gastroenteritis. Increasing duration of diarrhoea, younger age, and female sex increased this risk, whereas vomiting as part of the illness reduced the risk. One in 14 developed the irritable bowel syndrome with an increased risk seen in women (relative risk 3.4: 95% confidence interval 1.2 to 9.8) and with duration of diarrhoea (6.5; 1.3 to 34 for 15-21 days).

CONCLUSIONS

Persistence of bowel symptoms commonly occurs after bacterial gastroenteritis and is responsible for considerable morbidity and health care costs.

Eradication of Helicobacter pylori using one-week triple therapies combining omeprazole with two antimicrobials: the MACH I Study

BACKGROUND

Eradication of Helicobacter pylori provides potential cure in the majority of patients with peptic ulcer disease, and eradication rates of more than 90% have been reported, using omeprazole in combination with two antimicrobials. The choice of antimicrobials, dose regimen and duration of treatment have varied between studies, however, and an optimal treatment still has to be established.

MATERIALS AND METHODS

We conducted an international, randomized, double-blind, placebo-controlled study involving more than 100 patients in each of six treatment groups in 43 hospital gastrointestinal units in Canada, Germany, Ireland, Sweden, and the United Kingdom. Patients (n = 787) with proved duodenal ulcer disease were randomized to treatment twice daily for 1 week with omeprazole, 20 mg (O), plus either placebo (P) or combinations of two of the following antimicrobials: amoxicillin, 1 gm (A), clarithromycin, 250 or 500 mg (C250, C500), or metronidazole, 400 mg (M). Eradication of H. pylori was evaluated by 13C-UBT, performed before and 4 weeks after treatment cessation.

RESULTS

The eradication rates for the all-patients-treated analysis were 96%, OAC500; 95%, OMC250; 90%, OMC500; 84%, OAC250; 79%, OAM; and 1%, OP. OAC500 and OMC250 achieved eradication rates with lower 95% confidence interval limits exceeding 90%. All regimens were well-tolerated, 96% of patients complied with their dose regimen, and 2.3% of the patients discontinued treatment owing to adverse events.

CONCLUSIONS

Omeprazole triple therapies given twice daily for 1 week produce high eradication rates, are well-tolerated, and are associated with high patient compliance. The two most effective therapies were those combining omeprazole, 20 mg, with either amoxicillin, 1 gm, plus clarithromycin, 500 mg, or metronidazole, 400 mg, plus clarithromycin, 250 mg, all given twice daily.

Development and validation of a pig model for colon-specific drug delivery

The purpose of this investigation was to develop a pig model for colonic drug delivery and to validate the model by determining whether the physiology of the pig colon had been significantly altered after the surgical implantation of a gut cannula into the terminal ileum of the pig. A fistula was created in the terminal ileum of the pig, and a cannula fitted for the purpose of directly administering drug formulations to a point just anterior to the ileocaeco-colonic valve of the gastrointestinal tract. The cephalic vein of the pig was also cannulated to enable continued blood sampling. Sulphasalazine was used as the model drug for the validation study. In the intact colon, sulphasalazine is metabolized by the gut microflora to sulphapyridine which is then absorbed. Sulphasalazine was administered orally to non-fistulated and fistulated pigs and then ileally, via the gut cannula, to fistulated pigs. Absorption of sulphapyridine was monitored by HPLC analysis of plasma samples. There was no significant difference in the absorption obtained for the three groups. Thus it is demonstrated that the colon physiology had not been altered. The colonic pig model is ideal for studying factors affecting the colonic absorption of drugs and as a means for developing drug delivery systems with improved absorption properties.

Achalasia and diet: assessment of the effect of achalasia on the diet of patients and their spouses

The effect of achalasia on the diet of patients and their spouses was investigated using a validated questionnaire. The discordance between the diet of the patients and their respective spouses was compared with matched controls. There is no statistically significant difference between the discordance of case couples and control couples. Patients with achalasia, and their spouses, eat a normal diet.

Management of constipation. 2. When fibre fails

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Enteral nutrition in malnourished patients with hepatic cirrhosis and acute encephalopathy

Ten patients with histologically proven cirrhosis, admitted in grade I to II acute hepatic coma, received in addition to a standard dietary protein free "anticoma" regime, a continuous nasogastric infusion of a branched-chain amino acid enriched chemically defined enteral diet (Hepaticaid) containing an equivalent of 70 g protein/day for a mean of 7.3 days (range 3-23). No complications of therapy were observed and, specifically, the use of fine bore tubes did not provoke variceal hemorrhage. Overall positive nitrogen balance (4.3 +/- 1.7 g N/day) was observed in patients fed 7 or more days. Improvement to coma grade 0 was seen in all patients save one, who died from hepatorenal failure. While serum ammonia levels remained elevated during the study period, there was a significant increase in the branched-chain/aromatic ratio (p less than 0.01) as plasma branched-chain amino acids rose (p less than 0.05) and tyrosine levels fell (p less than 0.05).