Showing papers in "Gut in 2001"

The risk of colorectal cancer in ulcerative colitis: a meta-analysis

Abstract: BACKGROUND AND AIMS Controversy surrounds the risk of colorectal cancer (CRC) in ulcerative colitis (UC). Many studies have investigated this risk and reported widely varying rates. METHODS A literature search using Medline with the explosion of references identified 194 studies. Of these, 116 met our inclusion criteria from which the number of patients and cancers detected could be extracted. Overall pooled estimates, with 95% confidence intervals (CI), of cancer prevalence and incidence were obtained using a random effects model on either the log odds or log incidence scale, as appropriate. RESULTS The overall prevalence of CRC in any UC patient, based on 116 studies, was estimated to be 3.7% (95% CI 3.2–4.2%). Of the 116 studies, 41 reported colitis duration. From these the overall incidence rate was 3/1000 person years duration (pyd), (95% CI 2/1000 to 4/1000). The overall incidence rate for any child was 6/1000 pyd (95% CI 3/1000 to 13/1000). Of the 41 studies, 19 reported results stratified into 10 year intervals of disease duration. For the first 10 years the incidence rate was 2/1000 pyd (95% CI 1/1000 to 2/1000), for the second decade the incidence rate was estimated to be 7/1000 pyd (95% CI 4/1000 to 12/1000), and in the third decade the incidence rate was 12/1000 pyd (95% CI 7/1000 to 19/1000). These incidence rates corresponded to cumulative probabilities of 2% by 10 years, 8% by 20 years, and 18% by 30 years. The worldwide cancer incidence rates varied geographically, being 5/1000 pyd in the USA, 4/1000 pyd in the UK, and 2/1000 pyd in Scandinavia and other countries. Over time the cancer risk has increased since 1955 but this finding was not significant (p=0.8). CONCLUSIONS Using new meta-analysis techniques we determined the risk of CRC in UC by decade of disease and defined the risk in pancolitics and children. We found a non-significant increase in risk over time and estimated how risk varies with geography.

Endoscopic mucosal resection for treatment of early gastric cancer

Abstract: BACKGROUND In Japan, endoscopic mucosal resection (EMR) is accepted as a treatment option for cases of early gastric cancer (EGC) where the probability of lymph node metastasis is low. The results of EMR for EGC at the National Cancer Center Hospital, Tokyo, over a 11 year period are presented. METHODS EMR was applied to patients with early cancers up to 30 mm in diameter that were of a well or moderately histologically differentiated type, and were superficially elevated and/or depressed (types I, IIa, and IIc) but without ulceration or definite signs of submucosal invasion. The resected specimens were carefully examined by serial sections at 2 mm intervals, and if histopathology revealed submucosal invasion and/or vessel involvement or if the resection margin was not clear, surgery was recommended. RESULTS Four hundred and seventy nine cancers in 445 patients were treated by EMR from 1987 to 1998 but submucosal invasion was found on subsequent pathological examination in 74 tumours. Sixty nine percent of intramucosal cancers (278/405) were resected with a clear margin. Of 127 cancers without “complete resection”, 14 underwent an additional operation and nine were treated endoscopically; the remainder had intensive follow up. Local recurrence in the stomach occurred in 17 lesions followed conservatively, in one lesion treated endoscopically, and in five lesions with complete resection. All tumours were diagnosed by follow up endoscopy and subsequently treated by surgery. There were no gastric cancer related deaths during a median follow up period of 38 months (3–120 months). Bleeding and perforation (5%) were two major complications of EMR but there were no treatment related deaths. CONCLUSION In our experience, EMR allows us to perform less invasive treatment without sacrificing the possibility of cure.

Gastric cancer and Helicobacter pylori: a combined analysis of 12 case control studies nested within prospective cohorts

Abstract: BACKGROUND: The magnitude of the association between Helicobacter pylori and incidence of gastric cancer is unclear. H pylori infection and the circulating antibody response can be lost with development of cancer; thus retrospective studies are subject to bias resulting from classifi- cation of cases as H pylori negative when they were infected in the past. AIMS: To combine data from all case control studies nested within prospective cohorts to assess more reliably the relative risk of gastric cancer associated with H pylori infection.To investigate variation in relative risk by age, sex, cancer type and subsite, and interval between blood sampling and cancer diagnosis. METHODS: Studies were eligible if blood samples for H pylori serology were collected before diagnosis of gastric cancer in cases. Identified published studies and two unpublished studies were included. Individual subject data were obtained for each. Matched odds ratios (ORs) and 95% confidence intervals (95% CI) were calculated for the association between H pylori and gastric cancer. RESULTS: Twelve studies with 1228 gastric cancer cases were considered. The association with H pylori was restricted to noncardia cancers (OR 3.0; 95% CI 2.3–3.8) and was stronger when blood samples for H pylori serology were collected 10+ years before cancer diagnosis (5.9; 3.4–10.3). H pylori infection was not associated with an altered overall risk of cardia cancer (1.0; 0.7–1.4). CONCLUSIONS: These results suggest that 5.9 is the best estimate of the relative risk of non-cardia cancer associated with H pylori infection and that H pylori does not increase the risk of cardia cancer. They also support the idea that when H pylori status is assessed close to cancer diagnosis, the magnitude of the non-cardia association may be underestimated.

Behaviour of Crohn's disease according to the Vienna classification: changing pattern over the course of the disease

Abstract: BACKGROUND Crohn9s disease is a heterogeneous disorder with both a genetic and environmental aetiology. Clinical classifications of the disease, such as the newly proposed Vienna classification, may help to define subgroups of patients suitable for studying the influence of specific genetic or environmental factors. AIM To assess the stability over the course of the disease of its location and behaviour, as determined according to the Vienna classification. PATIENTS AND METHODS The notes of 297 Crohn9s disease patients regularly followed up at our institution were carefully reviewed retrospectively. The behaviour and location of the disease according to the Vienna classification were determined at diagnosis and after 1, 3, 5, 10, 15, 20, and 25 years of follow up. The proportions of the different behaviours and locations of the disease were calculated at these time points. A statistical analysis of the evolution of these characteristics over 10 years was performed on a subgroup of 125 patients with at least 10 years of follow up. The influence of age at diagnosis on location and behaviour of the disease was assessed as well as the influence of location on the behaviour of the disease. RESULTS The location of the disease remained relatively stable over the course of the disease. Although the proportion of patients who had a change in disease location became statistically significant after five years (p=0.01), over 10 years only 15.9% of patients had a change in location (p CONCLUSIONS Location of Crohn9s disease, as defined by the Vienna classification, is a relatively stable phenotype which seems suitable for phenotype-genotype analyses. Behaviour of Crohn9s disease according to the Vienna classification varies dramatically over the course of the disease and cannot be used in phenotype-genotype analyses. The potential influence of genes on the behaviour of Crohn9s disease should be studied in subgroups of patients defined by their disease behaviour after a fixed duration of disease.

The role of small intestinal bacterial overgrowth, intestinal permeability, endotoxaemia, and tumour necrosis factor α in the pathogenesis of non-alcoholic steatohepatitis

Abstract: BACKGROUND Small intestinal bacterial overgrowth may contribute to the development of non-alcoholic steatohepatitis, perhaps by increasing intestinal permeability and promoting the absorption of endotoxin or other enteric bacterial products. AIMS To investigate the prevalence of small intestinal bacterial overgrowth, increased intestinal permeability, elevated endotoxin, and tumour necrosis factor α (TNF-α) levels in patients with non-alcoholic steatohepatitis and in control subjects. PATIENTS AND METHODS Twenty two patients with non-alcoholic steatohepatitis and 23 control subjects were studied. Small intestinal bacterial overgrowth was assessed by a combined 14 C-d-xylose and lactulose breath test. Intestinal permeability was assessed by a dual lactulose-rhamnose sugar test. Serum endotoxin levels were determined using the limulus amoebocyte lysate assay and TNF-α levels using an ELISA. RESULTS Small intestinal bacterial overgrowth was present in 50% of patients with non-alcoholic steatosis and 22% of control subjects (p=0.048). Mean TNF-α levels in non-alcoholic steatohepatitis patients and control subjects were 14.2 and 7.5 pg/ml, respectively (p=0.001). Intestinal permeability and serum endotoxin levels were similar in the two groups. CONCLUSIONS Patients with non-alcoholic steatohepatitis have a higher prevalence of small intestinal bacterial overgrowth, as assessed by the 14 C-d-xylose-lactulose breath test, and higher TNF-α levels in comparison with control subjects. This is not accompanied by increased intestinal permeability or elevated endotoxin levels.

Efficacy in standard clinical practice of colonoscopic polypectomy in reducing colorectal cancer incidence

Abstract: BACKGROUND Colorectal cancer is one of the leading causes of death from cancer in Western countries. Removal of adenomas is based on the assumption that it could lead to a reduction in the incidence of colorectal cancer, as demonstrated by the National Polyp Study in the USA. A critical issue is whether the benefit observed in clinical trials can also be observed in standard clinical practice. To address the issue, a multicentre Italian collaborative study was organised. METHODS The study cohort comprised 1693 subjects of both sexes, aged 40–69 years, enrolled between 1980 and 1987 following a total colon examination (TCE) (that is, total colonoscopy or colonoscopy and double contrast barium enema), with removal of at least one adenoma larger than 5 mm in diameter. Exclusion criteria were genetic syndromes, previous adenomas or colorectal cancer, previous colonic resection, inflammatory bowel disease, or sessile adenomas more than 3 cm in diameter. Follow up ended in December 1996 by TCE or telephone interview, and review of the medical records, clinical files, or death certificates. Incidence ratios for colorectal cancer were compared with expected age and sex specific incidences in the Italian general population. RESULTS Follow up data were obtained for 97.3% of cases for a total of 14 211 person/years. Mean follow up was 10.5 years. Six colorectal cancer cases (four in males, two in females) at various stages were ascertained (one at 29 months, two at five years, one at seven years, one at eight years, and one at 10 years from the index examination). The number of cancers expected in the reference population was 17.7 for an incidence ratio of 0.34 (confidence interval 0.23–0.63; p CONCLUSIONS Colonoscopic polypectomy substantially reduced the incidence of colorectal cancer in the cohort compared with that expected in the general population. These results are of particular relevance considering that those with adenomas are at increased risk of colorectal cancer and that this retrospective study was performed on data obtained in standard clinical practice. This observation strengthens the concept of effective population screening in view of the fact that adenomatous polyps are the most frequent neoplastic outcome of screening and their removal is associated with a decrease in the incidence of colorectal cancer.

Surveillance programme of cirrhotic patients for early diagnosis and treatment of hepatocellular carcinoma: a cost effectiveness analysis

Abstract: BACKGROUND—Hepatocellular carcinoma (HCC) is a major cause of death in cirrhotic patients. This neoplasm is associated with liver cirrhosis (LC) in more than 90% of cases. Early diagnosis and treatment of HCC are expected to improve survival of patients. AIMS—To assess the cost effectiveness of a surveillance programme of patients with LC for the early diagnosis and treatment of HCC. PATIENTS—A cohort of 313 Italian patients with LC were enrolled in the surveillance programme between March 1989 and November 1991. In the same period, 104 consecutive patients with incidentally detected HCC were referred to our centre and served as a control group. METHODS—Surveillance was based on ultrasonography (US) and α fetoprotein (AFP) determinations repeated at six month intervals. Risk factors for HCC were assessed by multivariate analysis (Cox model). Outcome measures analysed were: (1) number and size of tumours; (2) eligibility for treatment; and (3) survival of patients. Economic issues were: (1) overall cost of surveillance programme; (2) cost per treatable HCC; and (3) cost per year of life saved (if any). Costs were assessed according to charges for procedures at our university hospital. RESULTS—Surveillance lasted a mean of 56 (31) months (range 6-100). During the follow up, 61 patients (19.5%) developed HCC (unifocal at US in 49 cases), with an incidence of 4.1% per year of follow up. AFP, Child-Pugh classes B and C, and male sex were detected as independent risk factors for developing HCC. Only 42 (68.9%) of 61 liver tumours were treated by surgical resection, orthotopic liver transplantation, or local therapy. The cumulative survival rate of the 61 patients with liver tumours detected in the surveillance programme was significantly longer than that of controls (p=0.02) and multivariate analysis showed an association between surveillance and survival. The overall cost of the surveillance programme was US$753 226, the cost per treatable HCC was US$17 934, and the cost for year of life saved was US$112 993. CONCLUSION—Our surveillance policy of patients with LC requires a large number of resources and offers little benefit in terms of patient survival. The decision whether to adopt a surveillance policy towards HCC should rely on the prevalence of the disease in the population and on the resources of a particular country. Keywords: hepatocellular carcinoma; surveillance programme; cost effectiveness

Classification of oesophageal motility abnormalities

Abstract: Manometric examination of the oesophagus frequently reveals abnormalities whose cause is unknown and whose physiological importance is not clear. A large body of literature dealing with oesophageal motility abnormalities has evolved over the past few decades but comparisons among studies have been compromised by the lack of a widely accepted system for classifying the abnormal motility patterns, and by the lack of uniform diagnostic criteria for the putative disorders. Based on an extensive review and analysis of the literature, this report suggests an operational scheme to be used for the general classification of oesophageal motility abnormalities, and proposes standardised manometric criteria for the putative oesophageal motility disorders. By applying the guidelines proposed in this report, clinicians and researchers can determine if their patients fulfil the manometric criteria for a putative motility disorder. This should facilitate and improve comparisons among patients and studies. However, it is important to emphasise that fulfilment of the proposed criteria does not establish the clinical importance of the motility abnormalities.

Intestinal luminal pH in inflammatory bowel disease: possible determinants and implications for therapy with aminosalicylates and other drugs

Abstract: Measurements of luminal pH in the normal gastrointestinal tract have shown a progressive increase in pH from the duodenum to the terminal ileum, a decrease in the caecum, and then a slow rise along the colon to the rectum. Some data in patients with ulcerative colitis suggest a substantial reduction below normal values in the right colon, while limited results in Crohn's disease have been contradictory. Determinants of luminal pH in the colon include mucosal bicarbonate and lactate production, bacterial fermentation of carbohydrates and mucosal absorption of short chain fatty acids, and possibly intestinal transit. Alterations in these factors, as a result of mucosal disease and changes in diet, are likely to explain abnormal pH measurements in inflammatory bowel disease (IBD). It is conceivable that reduced intracolonic pH in active ulcerative colitis impairs bioavailability of 5-aminosalicylic acid from pH dependent release formulations (Asacol, Salofalk) and those requiring cleavage by bacterial azo reductase (sulphasalazine, olsalazine, balsalazide), but further pharmacokinetic studies are needed to confirm this possibility. Reports that balsalazide and olsalazine may be more efficacious in active and quiescent ulcerative colitis, respectively, than Asacol suggest that low pH may be a more critical factor in patients taking directly pH dependent release than azo bonded preparations. Reduced intracolonic pH also needs to be considered in the development of pH dependent colonic release formulations of budesonide and azathioprine for use in ulcerative and Crohn's colitis. This paper reviews methods for measuring gut pH, its changes in IBD, and how these may influence current and future therapies.

Age and disease related changes in intestinal bacterial populations assessed by cell culture, 16S rRNA abundance, and community cellular fatty acid profiles

Abstract: Background—The normal intestinal microflora plays an important role in host metabolism and provides a natural defence mechanism against invading pathogens. Although the microbiota in adults has been extensively studied, little is known of the changes that occur in the microflora with aging. These may have important consequences in elderly people, many of whom are receiving antibiotic therapy and who are most susceptible to intestinal dysbiosis. Aims—To characterise the major groups of faecal bacteria in subjects of diVerent ages using a combination of cultural, molecular, and chemotaxonomic approaches. Methods—Comparative microbiological studies were made on four diVerent subject groups: children (16 months to seven years, n=10), adults (21‐34 years, n=7), healthy elderly subjects (67‐88 years, n=5), and geriatric patients (68‐73 years, n=4) diagnosed with Clostridium diYcile diarrhoea. Selected faecal bacteria were investigated using viable counting procedures, 16S ribosomal RNA (rRNA) abundance measurements, and the occurrence of specific signature fatty acids in whole community fatty acid methyl ester profiles. Results—The principal microbiological diVerence between adults and children was the occurrence of higher numbers of enterobacteria in the latter group, as determined by viable counts (p<0.05) and 16S rRNA (p<0.01) measurements. Moreover, a greater proportion of children’s faecal rRNA was hybridised by the three probes (bifidobacteria, enterobacteria, bacteroides-porphyromonasprevotella) used in the study, indicating a less developed gut microbiota. Species diversity was also markedly lower in the Clostridium diYcile associated diarrhoea group, which was characterised by high numbers of facultative anaerobes and low levels of bifidobacteria and bacteroides. Although it was a considerably less sensitive diagnostic tool, cellular fatty acid analysis correlated with viable bacterial counts and 16S rRNA measurements in a number of bacteria, including bacteroides. Conclusions—Polyphasic analysis of faecal bacteria showed that significant structural changes occur in the microbiota with aging, and this was especially evident with respect to putatively protective bifidobacteria. Reductions in these organisms in the large bowel may be related to increased disease risk in elderly people. (Gut 2001;48:198‐205)

Microsatellite instability and the clinicopathological features of sporadic colorectal cancer

Abstract: BACKGROUND AND AIMS In this study, we prospectively examined the clinical significance of the microsatellite instability (MSI) phenotype in sporadic colorectal cancer, and investigated methods for effective identification of these tumours in routine pathology practice. METHODS DNA was extracted from 310 tumours collected from 302 consecutive individuals undergoing curative surgery for sporadic colorectal cancer. Microsatellite status was determined by polymerase chain reaction amplification using standard markers, while immunostaining was used to examine expression of MLH1, MSH2, and p53. RESULTS Eleven per cent of tumours showed high level instability (MSI-H), 6.8% had low level instability (MSI-L), and the remainder were stable. MSI-H tumours were significantly more likely to be of high histopathological grade, have a mucinous phenotype, and to harbour increased numbers of intraepithelial lymphocytes. They were also more likely to be right sided, occur in women, and be associated with improved overall survival. In total, 25 (8%) tumours showed loss of staining for MLH1 and a further three tumours showed absence of staining for MSH2. The positive and negative predictive value of immunohistochemistry in the detection of MSI-H tumours was greater than 95%. CONCLUSIONS We conclude that the MSI-H phenotype constitutes a pathologically and clinically distinct subtype of sporadic colorectal cancer. Immunohistochemical staining for MLH1 and MSH2 represents an inexpensive and accurate means of identifying such tumours.

Increase in mortality rates from intrahepatic cholangiocarcinoma in England and Wales 1968-1998.

Abstract: BACKGROUND The age standardised mortality rate per 100 000 population for all causes of liver tumours (International Classification of Disease 9 (ICD-9) 155) has almost doubled in England and Wales during the period 1979–1996. We further analysed the mortality statistics to determine which anatomical subcategories were involved. METHODS Mortality statistics for liver tumours of ICD-9 155, 156, and subcategories, and for tumours of the pancreas (ICD-9 157), in England and Wales were investigated from the Office for National Statistics, London, from 1968 to 1996 inclusive. Data for 1997 and 1998 were also available on intrahepatic cholangiocarcinomas. RESULTS There has been a marked rise in age standardised mortality rates for intrahepatic cholangiocarcinoma. Since 1993, it represents the commonest recorded cause of liver tumour related death in England and Wales. This is evident in age groups older than 45 years. In contrast, mortality trends from other primary liver tumours, including hepatocellular carcinoma, were unremarkable. CONCLUSIONS The observed increase in mortality from intrahepatic cholangiocarcinoma may represent better case ascertainment and diagnosis due to improved diagnostic imaging, use of image guided biopsies, or increased use of ERCP. However, the trend started before ERCP was introduced nationally, mortality rates have continued to increase steadily thereafter, and there is no clear evidence that diagnostic transfers easily explains the findings. Alternatively, these observations may represent a true increase in intrahepatic bile duct tumours. Epidemiological studies are required to determine whether there is any geographical clustering of cases around the UK.

A systematic review of the staging performance of endoscopic ultrasound in gastro-oesophageal carcinoma

Abstract: BACKGROUND Endoscopic ultrasound (EUS) may be used for preoperative staging of gastro-oesophageal carcinoma but performance values given in the literature differ. AIMS To identify and synthesise findings from all articles on the performance of EUS in tumour, node, metastasis (TNM) staging of gastro-oesophageal carcinoma. SOURCE Published and unpublished English language literature, 1981–1996. METHODS Data on the staging performance of EUS were retrieved and evaluated. Summary receiver operator characteristic methodology was used for synthesis, and a summary estimate of performance, Q*, obtained. Multiple regression analysis was used to assess study validity and investigate reasons for differences in performance. RESULTS Twenty seven primary articles were assessed in detail. Thirteen supplied results for staging oesophageal cancer, 13 for gastric cancer, and four for cancers at the gastro-oesophageal junction. For gastric T staging, Q*=0.93 (95% confidence interval (CI) 0.91–0.95) and for oesophageal T staging, Q*=0.89 (95% CI 0.88–0.92). For gastro-oesophageal T staging, including cancers at the gastro-oesophageal junction, Q*=0.91 (95% CI 0.89–0.93). Inclusion of cases with non-traversable stenosis was found to slightly reduce staging performance. For N staging, Q*=0.79 (95% CI 0.75–0.83). In articles that compared EUS directly with incremental computed tomography, EUS performed better. None of the variables assessed in the regression analysis was significant using a Bonferroni correction. Three variables (anatomical location, traversability, and blinding) showed strong relationships for future research and validation. CONCLUSIONS EUS is highly effective for discrimination of stages T1 and T2 from stages T3 and T4 for primary gastro-oesophageal carcinomas. The failure rate of EUS from non-traversability of a stenotic cancer may be a limitation in some patient groups.

Impaired transit and tolerance of intestinal gas in the irritable bowel syndrome

Abstract: Background—Patients with irritable bowel syndrome (IBS) frequently complain of excessive gas but their fasting volume of intestinal gas is apparently normal. We hypothesised that the pathophysiological mechanism involved may be impairment of intestinal gas transit. Aim—To investigate intestinal gas transit and tolerance in IBS patients compared with healthy subjects. Methods—A gas mixture (N2 ,O 2, and CO2 in venous proportions) was infused into the jejunum of 20 patients with IBS and 20 healthy controls at 12 ml/min for four hours. Gas evacuation, initially flatus from the anus (two hours) and then intrarectally (two hours), was continuously recorded. Symptom perception (0‐6 scale) and abdominal distension were measured at 10 minute intervals. Results—After two hours of external gas (flatus) collection, 18 of 20 IBS patients had developed gas retention (>400 ml), increased gastrointestinal symptoms (score >3), or abdominal distension (>3 mm girth increment) compared with only four of 20 control subjects. During intrarectal gas collection, 13 of 17 patients still exhibited abnormal responses. Conclusion—A large proportion of patients with IBS can be shown to have impaired transit and tolerance of intestinal gas loads.This anomaly may represent a possible mechanism of IBS symptoms, specifically pain and bloating. (Gut 2001;48:14‐19)

The importance of interleukin 1beta in Helicobacter pylori associated disease.

Abstract: Helicobacter pylori infection is associated with divergent clinical outcomes that range from simple asymptomatic gastritis to more serious conditions such as peptic ulcer disease and gastric neoplasia. The key determinants of these outcomes are the severity and distribution of the H pylori induced gastritis. Gastritis that is largely confined to the antral region is associated with excessive acid secretion and a high risk of duodenal ulcer disease.1 In contrast, gastritis that involves the acid secreting corpus region leads to hypochlorhydria, progressive gastric atrophy, and an increased risk of gastric cancer.2 The association of H pylori with such variable outcome poses a fascinating scientific challenge, the unravelling of which will not only explain how ulcers and gastric cancer develop but will also act as a paradigm for gene-environment interactions in most human diseases. The proinflammatory cytokine interleukin (IL)-1β is emerging as a key mediator of many pathophysiological events that characterise host-environment interactions. In this article we discuss the role of IL-1β in H pylori associated disease. The key pathophysiological event in H pylori infection is initiation of an inflammatory response. Bacteria or their products trigger this inflammatory process and the main mediators are cytokines. Cytokines, including interleukins, are soluble peptide molecules that mediate the interaction between immunocompetent and haematopoietic cells and between the immune and neuroendocrine systems.3 They are produced by a variety of activated cells and exert their biological effects through binding to specific receptors on target cells. IL-1β is the archetypal pleiotropic cytokine being produced by many cells and exerting its biological effects on almost all cell types.4 IL-1β is a potent proinflammatory cytokine and is involved in the host's response to many antigenic challenges. Nearly all microbes/microbial products and many non-microbial agents stimulate transcription and synthesis of IL-1β. Some of the more interesting non-microbial …

Apoptosis of hepatic stellate cells: involvement in resolution of biliary fibrosis and regulation by soluble growth factors

Abstract: Background—Activated hepatic stellate cells (HSC) are central to the pathogenesis of liver fibrosis, both as a source of fibrillar collagens that characterise fibrosis and matrix degrading metalloproteinases and their tissue inhibitors, the TIMPs. Aims—To test the hypothesis that HSC apoptosis is critical to recovery from biliary fibrosis and that soluble growth factors may regulate HSC survival and apoptosis. Methods—Rats (n=15) were subjected to bile duct ligation for 21 days, after which biliodigestive anastomosis was undertaken (n=13). Livers were harvested at fixed time points of recovery for periods of up to 42 days. Numbers of activated HSCs were quantified after AE smooth muscle actin staining and HSC apoptosis was detected by terminal UDP-nick end labelling (TUNEL) staining and quantified at each time point. HSC apoptosis was quantified in vitro in the presence or absence of insulin-like growth factor (IGF)-1, IGF-2, platelet derived growth factor (PDGF), and transforming growth factor ‚1 (TGF-‚1). Results—Following biliodigestive anastomosis after 21 days of bile duct ligation, rat liver demonstrated a progressive resolution of biliary fibrosis over 42 days, associated with a fivefold decrease in activated HSC determined by AE smooth muscle actin staining. TUNEL staining indicated that loss of activated HSC resulted from an increase in the rate of apoptosis during the first two days post biliodigestive anastomosis. Serum deprivation and culture in the presence of 50 µM cycloheximide was associated with an increase in HSC apoptosis which was significantly inhibited by addition of 10 ng/ml and 100 ng/ml IGF-1, respectively (0.05>p, n=5). In contrast, 1 and 10 ng/ml of TGF-‚1 caused a significant increase in HSC apoptosis compared with serum free controls (p<0.05, n=4). PDGF and IGF-2 were neutral with respect to their eVect on HSC apoptosis. Conclusion—HSC apoptosis plays a critical role in the spontaneous recovery from biliary fibrosis. Both survival and apoptosis of HSC are regulated by growth factors expressed during fibrotic liver injury. (Gut 2001;48:548‐557)

Double blind, randomised, placebo controlled study of a platelet activating factor antagonist, lexipafant, in the treatment and prevention of organ failure in predicted severe acute pancreatitis

Abstract: BACKGROUND—Platelet activating factor (PAF) is believed to amplify the activity of key mediators of the systemic inflammatory response syndrome (SIRS) in acute pancreatitis, resulting in multiorgan dysfunction syndrome. We tested the hypothesis that a potent PAF antagonist, lexipafant, could dampen SIRS and reduce organ failure in severe acute pancreatitis. METHODS—We conducted a randomised, double blind, placebo controlled, multicentre trial of lexipafant (100 mg/24 hours intravenously for seven days commenced within 72 hours of the onset of symptoms) involving 290 patients with an APACHE II score >6. Power calculations assumed that complications would be reduced from 40% to 24%. Secondary end points studied included severity of organ failure, markers of the inflammatory response, and mortality rate. FINDINGS—Overall, 80/138 (58%) patients in the placebo group and 85/148 (57%) in the lexipafant group developed one or more organ failures. The primary hypothesis was invalidated by the unexpected finding that 44% of patients had organ failure on entry into the study; only 39 (14%) developed new organ failure. Organ failure scores were reduced in the lexipafant group only on day 3: median change −1 (range −4 to +8) versus 0 (−4 to +10) in the placebo group (p=0.04). Systemic sepsis affected fewer patients in the lexipafant group (13/138 v 4/148; p=0.023). Local complications occurred in 41/138 (30%) patients in the placebo group and in 30/148 (20%) in the lexipafant group (20%; p=0.065); pseudocysts developed in 19 (14%) and eight (5%) patients, respectively (p=0.025). Deaths attributable to acute pancreatitis were not significantly different. Interleukin 8, a marker of neutrophil activation, and E-selectin, a marker of endothelial damage, decreased more rapidly in the lexipafant group (both p<0.05); however, absolute values were not different between the two groups. INTERPRETATION—The high incidence of organ failure within 72 hours of the onset of symptoms undermined the primary hypothesis, and power calculations for future studies in severe acute pancreatitis will need to allow for this. Lexipafant had no effect on new organ failure during treatment. This adequately powered study has shown that antagonism of PAF activity on its own is not sufficient to ameliorate SIRS in severe acute pancreatitis Keywords: platelet activating factor; organ failure; systemic inflammatory response syndrome; lexipafant; acute pancreatitis

Role of mast cells in chronic stress induced colonic epithelial barrier dysfunction in the rat.

Abstract: BACKGROUND AND AIMS Stress may be an important factor in exacerbating inflammatory bowel disease but the underlying mechanism is unclear. Defective epithelial barrier function may allow uptake of luminal antigens that stimulate an immune/inflammatory response. Here, we examined the effect of chronic stress on colonic permeability and the participation of mast cells in this response. METHODS Mast cell deficient Ws/Ws rats and +/+ littermate controls were submitted to water avoidance stress or sham stress (one hour/day) for five days. Colonic epithelial permeability to a model macromolecular antigen, horseradish peroxidase, was measured in Ussing chambers. Epithelial and mast cell morphology was studied by light and electron microscopy. RESULTS Chronic stress significantly increased macromolecular flux and caused epithelial mitochondrial swelling in +/+ rats, but not in Ws/Ws rats, compared with non-stressed controls. Stress increased the number of mucosal mast cells and the proportion of cells showing signs of activation in +/+ rats. No mast cells or ultrastructural abnormalities of the epithelium were present in Ws/Ws rats. Increased permeability in +/+ rats persisted for 72 hours after stress cessation. CONCLUSIONS Chronic stress causes an epithelial barrier defect and epithelial mitochondrial damage, in parallel with mucosal mast cell hyperplasia and activation. The study provides further support for an important role for mast cells in stress induced colonic mucosal pathophysiology.

Cannabinoids and the gastrointestinal tract

Abstract: The enteric nervous system of several species, including the mouse, rat, guinea pig and humans, contains cannabinoid CB 1 receptors that depress gastrointestinal motility, mainly by inhibiting ongoing contractile transmitter release. Signs of this depressant effect are, in the whole organism, delayed gastric emptying and inhibition of the transit of non-absorbable markers through the small intestine and, in isolated strips of ileal tissue, inhibition of evoked acetylcholine release, peristalsis, and cholinergic and non-adrenergic non-cholinergic (NANC) contractions of longitudinal or circular smooth muscle. These are contractions evoked electrically or by agents that are thought to stimulate contractile transmitter release either in tissue taken from morphine pretreated animals (naloxone) or in unpretreated tissue (γ-aminobutyric acid and 5-hydroxytryptamine). The inhibitory effects of cannabinoid receptor agonists on gastric emptying and intestinal transit are mediated to some extent by CB 1 receptors in the brain as well as by enteric CB 1 receptors. Gastric acid secretion is also inhibited in response to CB 1 receptor activation, although the detailed underlying mechanism has yet to be elucidated. Cannabinoid receptor agonists delay gastric emptying in humans as well as in rodents and probably also inhibit human gastric acid secretion. Cannabinoid pretreatment induces tolerance to the inhibitory effects of cannabinoid receptor agonists on gastrointestinal motility. Findings that the CB 1 selective antagonist/inverse agonist SR141716A produces in vivo and in vitro signs of increased motility of rodent small intestine probably reflect the presence in the enteric nervous system of a population of CB 1 receptors that are precoupled to their effector mechanisms. SR141716A has been reported not to behave in this manner in the myenteric plexus-longitudinal muscle preparation (MPLM) of human ileum unless this has first been rendered cannabinoid tolerant. Nor has it been found to induce “withdrawal” contractions in cannabinoid tolerant guinea pig ileal MPLM. Further research is required to investigate the role both of endogenous cannabinoid receptor agonists and of non-CB 1 cannabinoid receptors in the gastrointestinal tract. The extent to which the effects on gastrointestinal function of cannabinoid receptor agonists or antagonists/inverse agonists can be exploited therapeutically has yet to be investigated as has the extent to which these drugs can provoke unwanted effects in the gastrointestinal tract when used for other therapeutic purposes.

Utilisation of erythrocyte 6-thioguanine metabolite levels to optimise azathioprine therapy in patients with inflammatory bowel disease

Abstract: BACKGROUND AND AIM The immunosuppressive properties of 6-mercaptopurine and its parent compound azathioprine are mediated by their intracellular metabolism into active 6-thioguanine (6-TG) metabolites Measurement of erythrocyte 6-TG metabolite levels has been proposed as a useful clinical tool for assessing treatment efficacy in patients with inflammatory bowel disease (IBD) AIM The purpose of the study was to establish a therapeutic index of treatment efficacy based on measurement of erythrocyte 6-TG metabolite levels, and apply it clinically to guide therapy METHODS Heparinised blood was obtained from 82 adult patients with IBD on long term (more than three months) antimetabolite therapy (63 Crohn9s disease; 19 ulcerative colitis) Erythrocyte 6-TG metabolite levels were measured using reverse phase high performance chromatography, and correlated with treatment efficacy In 22 patients with refractory Crohn9s disease despite long term azathioprine therapy, their dosage was increased by 25 mg/day at eight week intervals as needed Serial erythrocyte 6-TG metabolite levels were measured at each clinic visit and correlated with treatment efficacy RESULTS Clinical remission, as defined by a low disease index score in patients weaned off or on a low alternate day dose ( 8 red blood cells in patients with colonic and fistulising Crohn9s disease (p 8 red blood cells (p 3 /μl with adjustment in azathioprine dosage No patient incurred azathioprine induced leucopenia CONCLUSION Measurement of erythrocyte 6-TG metabolite levels is helpful in determining the adequacy of azathioprine dosage and can be used to optimise the dose of antimetabolite therapy to achieve an improved clinical response without inducing leucopenia Patients who are clinically refractory to azathioprine therapy despite achieving high erythrocyte 6-TG levels (>250) should be considered for adjunct or alternative forms of immunosuppressive therapy or surgery

Extrahepatic portal vein thrombosis: aetiology and determinants of survival

Abstract: Background—Malignancy, hypercoagula- bility, and conditions leading to decreased portal flow have been reported to contrib- ute to the aetiology of extrahepatic portal vein thrombosis (EPVT). Mortality of pa- tients with EPVT may be associated with these concurrent medical conditions or with manifestations of portal hypertension, such as variceal haemorrhage. Patients and methods—To determine which variables have prognostic signifi- cance with respect to survival, we per- formed a retrospective study of 172 adult EPVT patients who were followed over the period 1984-1997 in eight university hospi- tals. Results—Mean follow up was 3.9 years (range 0.1-13.1). Overall survival was 70% (95% confidence interval (CI) 62-76%) at one year, 61% (95% CI, 52-67%) at five years, and 54% (95% CI, 45-62%) at 10 years. The one, five, and 10 year survival rates in the absence of cancer, cirrhosis, and mesenteric vein thrombosis were 95% (95% CI 87-98%), 89% (95% CI 78-94%), and 81% (95% CI 67-89%), respectively (n=83). Variables at diagnosis associated with reduced survival according to multi- variate analysis were advanced age, malignancy, cirrhosis, mesenteric vein thrombosis,absence of abdominal inflam- mation, and serum levels of aminotrans- ferase and albumin. The presence of variceal haemorrhage and myeloprolif- erative disorders did not influence sur- vival. Only four patients died due to variceal haemorrhage and one due to complications of a portosystemic shunt procedure. Conclusion—We conclude that mortality among patients with EPVT is related primarily to concurrent disorders leading to EPVT and not to complications of por- tal hypertension. (Gut 2001;49:720-724)

Potential benefits and hazards of physical activity and exercise on the gastrointestinal tract

Abstract: This review describes the current state of knowledge on the hazards of exercise and the potential benefits of physical activity on the gastrointestinal tract. In particular, acute strenuous exercise may provoke gastrointestinal symptoms such as heartburn or diarrhoea. A substantial part (20-50%) of endurance athletes are hampered by these symptoms which may deter them from participation in training and competitive events. Nevertheless, these acute symptoms are transient and do not hamper the athlete's health in the long term. The only exception is repeated gastrointestinal bleeding during training and competition, which in the long term may occasionally lead to iron deficiency and anaemia. In contrast, repetitive exercise periods at a relatively low intensity may have protective effects on the gastrointestinal tract. There is strong evidence that physical activity reduces the risk of colon cancer by up to 50%. Less convincing evidence exists for cholelithiasis and constipation. Physical activity may reduce the risk of diverticulosis, gastrointestinal haemorrhage, and inflammatory bowel disease although this cannot be substantiated firmly. Up to now, underlying mechanisms are poorly understood although decreased gastrointestinal blood flow, neuro-immuno-endocrine alterations, increased gastrointestinal motility, and mechanical bouncing during exercise are postulated. Future research on exercise associated digestive processes should give more insight into the relationship between physical activity and the function of the gastrointestinal tract.

Can APC mutation analysis contribute to therapeutic decisions in familial adenomatous polyposis? Experience from 680 FAP families

Abstract: BACKGROUND AND AIMS In familial adenomatous polyposis (FAP), correlations between site of mutation in the adenomatous polyposis coli ( APC ) gene and severity of colonic polyposis or extracolonic manifestations are well known. While mutation analysis is important for predictive diagnosis in persons at risk, its relevance for clinical management of individual patients is open to question. METHODS We examined 680 unrelated FAP families for germline mutations in the APC gene. Clinical information was obtained from 1256 patients. RESULTS APC mutations were detected in 48% (327/680) of families. Age at diagnosis of FAP based on bowel symptoms and age at diagnosis of colorectal cancer in untreated patients were used as indicators of the severity of the natural course of the disease. A germline mutation was detected in 230 of 404 patients who were diagnosed after onset of bowel symptoms (rectal bleeding, abdominal pain, diarrhoea). When these patients were grouped according to the different sites of mutations, mean values for age at onset of disease differed significantly: patients carrying APC mutations at codon 1309 showed a disease onset 10 years earlier (mean age 20 years) compared with patients with mutations between codons 168 and 1580 (except codon 1309) (mean age 30 years), whereas patients with mutations at the 5′ end of codon 168 or the 3′ end of codon 1580 were diagnosed at a mean age of 52 years. Within each group of patients however large phenotypic variation was observed, even among patients with identical germline mutations. A higher incidence of desmoids was found in patients with mutations between codons 1445 and 1580 compared with mutations at other sites, while no correlation between site of mutation and presence of duodenal adenomas was observed. CONCLUSIONS As age at manifestation and course of the disease may be rather variable, even in carriers of identical germline mutations, therapeutic decisions should be based on colonoscopic findings in individual patients rather than on the site of mutation. However, in patients with mutations within codons 1445–1580, it may be advisable to postpone elective colectomy because desmoids may arise through surgical intervention.

Predictive factors for regression of gastric MALT lymphoma after anti-Helicobacter pylori treatment.

Abstract: BACKGROUND AND AIMS Discrepant remission rates (41–100%) have been reported for patients with localised low grade gastric mucosa associated lymphoid tissue (MALT) lymphoma after eradication of Helicobacter pylori . The aim of this study was to explain these discrepancies and to determine the predictive factors of gastric lymphoma regression after anti- H pylori treatment. PATIENTS AND METHODS Forty six consecutive patients with localised gastric MALT lymphoma (Ann Arbor stages I E and II E ) were prospectively enrolled. All had gastric endoscopic ultrasonography and H pylori status assessment (histology, culture, polymerase chain reaction, and serology). After anti- H pylori treatment, patients were re-examined every four months. RESULTS Histological regression of the lymphoma was complete in 19/44 patients (43%) (two lost to follow up). Median follow up time for these 19 responders was 35 months (range 10–47). No regression was noted in the 10 H pylori negative patients. Among the 34 H pylori positive patients, the H pylori eradication rate was 100%; complete regression rate of the lymphoma increased from 56% (19/34) to 79% (19/24) when there was no nodal involvement at endoscopic ultrasonography. There was a significant difference between the response of the lymphoma restricted to the mucosa and other more deep seated lesions (p CONCLUSION In H pylori positive patients with localised gastric MALT lymphoma, carefully evaluated and treated without any lymph node involvement assessed by endoscopic ultrasonography, complete remission of lymphoma was reached in 79% of cases.

Enhanced glypican-3 expression differentiates the majority of hepatocellular carcinomas from benign hepatic disorders

Abstract: BACKGROUND/AIMS Hepatocellular carcinoma (HCC) is a common malignant tumour worldwide, and its differential diagnosis from benign lesions of the liver is often difficult yet of great clinical importance. In the present study, we analysed whether glypican-3 is useful in differentiating between benign and malignant liver diseases and whether it influences the growth behaviour of HCC. METHODS Northern blot analysis and in situ hybridisation. RESULTS Northern blot analysis indicated that expression of glypican-3 mRNA was either low or absent in normal liver, in focal nodular hyperplasia (FNH), and in liver cirrhosis. In contrast, expression of glypican-3 mRNA was markedly increased in 20 of 30 and moderately increased in five of 30 HCC samples. The average increase in glypican-3 mRNA expression in HCC was significant compared with expression in normal liver (21.7-fold increase, p CONCLUSIONS These findings suggest that glypican-3, in many cases, has the potential to differentiate between benign and malignant liver diseases.

Cyclooxygenase 2—implications on maintenance of gastric mucosal integrity and ulcer healing: controversial issues and perspectives

Abstract: Cyclooxygenase (COX), the key enzyme for synthesis of prostaglandins, exists in two isoforms (COX-1 and COX-2). COX-1 is constitutively expressed in the gastrointestinal tract in large quantities and has been suggested to maintain mucosal integrity through continuous generation of prostaglandins. COX-2 is induced predominantly during inflammation. On this premise selective COX-2 inhibitors not affecting COX-1 in the gastrointestinal tract mucosa have been developed as gastrointestinal sparing anti-inflammatory drugs. They appear to be well tolerated by experimental animals and humans following acute and chronic (three or more months) administration. However, there is increasing evidence that COX-2 has a greater physiological role than merely mediating pain and inflammation. Thus gastric and intestinal lesions do not develop when COX-1 is inhibited but only when the activity of both COX-1 and COX-2 is suppressed. Selective COX-2 inhibitors delay the healing of experimental gastric ulcers to the same extent as non-COX-2 specific non-steroidal anti-inflammatory drugs (NSAIDs). Moreover, when given chronically to experimental animals, they can activate experimental colitis and cause intestinal perforation. The direct involvement of COX-2 in ulcer healing has been supported by observations that expression of COX-2 mRNA and protein is upregulated at the ulcer margin in a temporal and spatial relation to enhanced epithelial cell proliferation and increased expression of growth factors. Moreover, there is increasing evidence that upregulation of COX-2 mRNA and protein occurs during exposure of the gastric mucosa to noxious agents or to ischaemia-reperfusion. These observations support the concept that COX-2 represents (in addition to COX-1) a further line of defence for the gastrointestinal mucosa necessary for maintenance of mucosal integrity and ulcer healing.

The cardiac response to exercise in cirrhosis

Abstract: BACKGROUND—Impaired exercise capacity and oxygen consumption are common in cirrhosis. AIM—To explore the relationship between possible myocardial dysfunction and exercise tolerance in cirrhosis. METHODS—Cardiac responses to exercise, using radionuclide angiography and graded upright cycle ergometry with oxygen consumption, were assessed before and after exercise in 39 cirrhotics patients and compared with 12 age and sex matched healthy volunteers. Baseline cardiac chamber dimensions and wall thickness, ejection fraction, and diastolic function were measured using two dimensional echocardiography is all subjects. RESULTS—Baseline diastolic dysfunction with prolonged isovolumic relaxation times (p=0.02), left atrial enlargement, and left ventricular wall thickening were present in all cirrhotics (p=0.02), despite increased mean ejection fraction. With graded exercise, cirrhotics achieved 71 (4)% (p=0.03) (pre-ascitics) and 46 (3)% (p<0.001) (ascitics) of predicted work loads, respectively, without significant increases in ejection fraction. The smaller absolute and percentage increases in cardiac output (p=0.003) in the cirrhotics were associated with significantly reduced oxygen consumption (p=0.003) and anaerobic threshold (p<0.001), and correlated significantly with work and metabolic parameters. CONCLUSIONS—Impaired exercise capacity in cirrhosis is associated with myocardial thickening and ventricular stiffness leading to decreased diastolic function, inotropic and chronotropic incompetence under conditions of stress, with metabolic consequences. This picture is compatible with the condition now known as cirrhotic cardiomyopathy. Keywords: cirrhosis; exercise tolerance; myocardial function; oxygen consumption

High level perinuclear antineutrophil cytoplasmic antibody (pANCA) in ulcerative colitis patients before colectomy predicts the development of chronic pouchitis after ileal pouch-anal anastomosis

Abstract: BACKGROUND The reported cumulative risk of developing pouchitis in ulcerative colitis (UC) patients undergoing ileal pouch-anal anastomosis (IPAA) approaches 50% after 10 years. To date, no preoperative serological predictor of pouchitis has been found. AIMS To assess whether preoperative perinuclear antineutrophil cytoplasmic antibody (pANCA) expression was associated with acute and/or chronic pouchitis after IPAA. METHODS Patients were prospectively assessed for the development of clinically and endoscopically proved pouchitis. Serum obtained at the time of colectomy in 95 UC patients undergoing IPAA was analysed for pANCA by ELISA and indirect immunofluorescence. pANCA+ patients were stratified into high level (>100 ELISA units (EU)/ml) (n=9), moderate level (40–100 EU/ml) (n=32), and low level ( RESULTS Sixty of the 95 patients (63%) expressed pANCA. After a median follow up of 32 months (range 1–89), 32 patients (34%) developed either acute (n=14) or chronic (n=18) pouchitis. Pouchitis was seen in 42% of pANCA+ patients compared with 20% of pANCA− patients (p=0.09). There was no significant difference in the incidence of acute pouchitis between the three pANCA+ patient subgroups. The cumulative risk of developing chronic pouchitis among patients with high level pANCA (56%) before colectomy was significantly higher than in patients with medium level (22%), low level (16%), and those who were pANCA− (20%) (p = 0.005). Multivariate analysis revealed that the sole parameter significantly associated with the development of chronic pouchitis after IPAA was the presence of high level pANCA before colectomy (p=0.005). CONCLUSION High level pANCA before colectomy is significantly associated with the development of chronic pouchitis after IPAA.

Secular trends in the epidemiology and outcome of Barrett's oesophagus in Olmsted County, Minnesota.

Abstract: Background—The incidence of oesophageal adenocarcinoma has increased greatly. Barrett’s oesophagus is a known risk factor. Aims—To identify changes in the incidence, prevalence, and outcome of Barrett’s oesophagus in a defined population. Subjects—Residents of Olmsted County, Minnesota, with clinically diagnosed Barrett’s oesophagus, or oesophageal or oesophagogastric junction adenocarcinoma. Methods—Cases were identified using the Rochester Epidemiology Project medical records linkage system. Records were reviewed with follow up to 1 January 1998. Results—The incidence of clinically diagnosed Barrett’s oesophagus (>3 cm) increased 28-fold from 0.37/100 000 person years in 1965‐69 to 10.5/100 000 in 1995‐97. Of note, gastroscopic examinations increased 22-fold in this same time period. The prevalence of diagnosed Barrett’s oesophagus increased from 22.6 (95% confidence interval (CI) 11.7‐33.6) per 100 000 in 1987 to 82.6/100 000 in 1998. The prevalence of short segment Barrett’s oesophagus (<3 cm) in 1998 was 33.4/ 100 000. Patients with Barrett’s oesophagus had shorter than expected survival but only one patient with Barrett’s oesophagus died from adenocarcinoma. Only four of 64 adenocarcinomas occurred in patients with previously known Barrett’s oesophagus. Conclusions—The incidence and prevalence of clinically diagnosed Barrett’s oesophagus have increased in parallel with the increased use of endoscopy. We infer that the true population prevalence of Barrett’s oesophagus has not changed greatly, although the incidence of oesophageal adenocarcinoma increased 10-fold. Many adenocarcinomas occurred in patients without a previous diagnosis of Barrett’s oesophagus, suggesting that many people with this condition remain undiagnosed in the community. (Gut 2001;48:304‐309)

Escherichia coli strains colonising the gastrointestinal tract protect germfree mice against Salmonella typhimurium infection

Abstract: BACKGROUND—Escherichia coli is part of the normal gastrointestinal microflora which exerts a barrier effect against enteropathogens. Several E coli strains develop a protective effect against other Enterobacteriaceae. AIMS—Two E coli strains, EM0, a human faecal strain, and JM105 K-12 were tested for their ability to prevent in vivo and in vitro infection by Salmonella typhimurium C5. METHODS—Inhibition of C5 cell invasion by E coli was investigated in vitro using Caco-2/TC7 cells. The protective effect of E coli was examined in vivo in germfree or conventional C3H/He/Oujco mice orally infected by the lethal strain C5. RESULTS—EMO expresses haemolysin and cytotoxic necrotising factor in vitro. In vitro, the two strains did not prevent the growth of C5 by secreted microcins or modified cell invasion of C5. In vivo, establishment of EM0 or JM105 in the gut of germfree mice resulted in a significant increase in the number of surviving mice: 11/12 and 9/12, respectively, at 58 days after infection (2×106/mouse) versus 0/12 in control germfree group at 13 days after infection. Colonisation level and translocation rate of C5 were significantly reduced during the three days after infection. In contrast, no reduction in faecal C5 excretion was observed in C5 infected conventional mice (1×108/mouse) receiving the EM0 or JM105 cultures daily. CONCLUSIONS—Establishment of E coli strains, which do not display antimicrobial activity, protects germfree mice against infection and delays the establishment of C5 in the gut. Possible mechanisms of defence are discussed. Keywords: Escherichia coli; gastrointestinal infection; Salmonella; germfree mice; bacterial antagonism