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Purpose: In obesity and diabetes the liver is highly susceptible to abnormal uptake and storage of fat. In certain individuals hepatic steatosis predisposes to the development of non-alcoholic steatohepatitis (NASH), a disease marked by hepatic inflammation and fibrosis. Although the precise pathophysiology of NASH is unknown, it is believed that the gut microbiota-liver axis influences the development of this disease. With few treatment strategies available for NASH, exploration of gut microbiota-targeted interventions is warranted. We investigated the therapeutic potential of a prebiotic supplement to improve histological parameters of NASH., Methods: In a placebo-controlled, randomized pilot trial, 14 individuals with liver-biopsy-confirmed NASH [non-alcoholic fatty liver activity score (NAS) ≥ 5] were randomized to receive oligofructose (8 g/day for 12 weeks followed by 16 g/day for 24 weeks) or isocaloric placebo for 9 months. The primary outcome measure was the change in liver biopsy NAS score and the secondary outcomes included changes in body weight, body composition, glucose tolerance, inflammatory markers, and gut microbiota., Results: Independent of weight loss, oligofructose improved liver steatosis relative to placebo and improved overall NAS score (P = 0.016). Bifidobacterium was enhanced by oligofructose, whereas bacteria within Clostridium cluster XI and I were reduced with oligofructose (P < 0.05). There were no adverse side effects that deterred individuals from consuming oligofructose for treatment of this disease., Conclusions: Independent of other lifestyle changes, prebiotic supplementation reduced histologically-confirmed steatosis in patients with NASH. Larger follow-up studies are warranted., Clinical Trial: This trial was registered at Clinicaltrials.com as NCT03184376.

Background: Mycophenolate mofetil (MMF) is commonly prescribed after transplantation and has major advantages over other immunosuppressive drugs, but frequent gastrointestinal (GI) side-effects limit its use. The mechanism(s) underlying MMF-related GI toxicity have yet to be elucidated., Methods: To investigate MMF-related GI toxicity, experimental mice were fed chow containing MMF (0.563%) and multiple indices of toxicity, including weight loss and colonic inflammation, were measured. Changes in intestinal microbial composition were detected using 16S rRNA Illumina sequencing, and downstream PICRUSt analysis was used to predict metagenomic pathways involved. Germ-free (GF) mice and mice treated with orally administered broad-spectrum antibiotics (ABX) were utilized to interrogate the importance of the microbiota in MMF-induced GI toxicity., Results: Mice treated with MMF exhibited significant weight loss, related to loss of body fat and muscle, and marked colonic inflammation. MMF exposure was associated with changes in gut microbial composition, as demonstrated by a loss of overall diversity, expansion of Proteobacteria (specifically Escherichia/Shigella), and enrichment of genes involved in lipopolysaccharide (LPS) biosynthesis, which paralleled increased levels of LPS in the feces and serum. MMF-related GI toxicity was dependent on the intestinal microbiota, as MMF did not induce weight loss or colonic inflammation in GF mice. Furthermore, ABX prevented and reversed MMF-induced weight loss and colonic inflammation., Conclusions: An intact intestinal microbiota is required to initiate and sustain the GI toxicity of MMF. MMF treatment causes dynamic changes in the composition of the intestinal microbiota that may be a targetable driver of the GI side-effects of MMF., (Copyright © 2018 International Society for Heart and Lung Transplantation. Published by Elsevier Inc. All rights reserved.)

Background and Purpose: The pathogenesis of the inflammatory bowel diseases (IBD), comprising Crohn's disease (CD) and ulcerative colitis (UC), involves aberrant interactions between a genetically susceptible individual, their microbiota and environmental factors. Alterations in xenobiotic receptor expression and function are associated with increased risk for IBD. Here, we have assessed the role of the constitutive androstane receptor (CAR), a xenobiotic receptor closely related to the pregnane X receptor, in the regulation of intestinal mucosal homeostasis., Experimental Approach: CAR expression was assessed in intestinal mucosal biopsies obtained from CD and UC patients, and in C57/Bl6 mice exposed to dextran sulphate sodium (DSS; 3.5% w/v in drinking water) to evoke intestinal inflammation and tissue damage. CAR-deficient mice were exposed to DSS and mucosal healing assessed. Modulation of wound healing by CAR was assessed in vitro. The therapeutic potential of CAR activation was evaluated, using 3,3',5,5'-tetrachloro-1,4-bis(pyridyloxy)benzene (TCPOBOP), a selective rodent CAR agonist., Key Results: CAR expression was reduced in CD and UC samples, compared with expression in healthy controls. This was reproduced in our DSS studies, where CAR expression was reduced in colitic mice. CAR-deficient mice exhibited reduced healing following DSS exposure. In vitro, CAR activation accelerated intestinal epithelial wound healing by enhancing cell migration. Lastly, treating mice with TCPOBOP, following induction of colitis, enhanced mucosal healing., Conclusion and Implications: Our results support the notion that xenobiotic sensing is altered during intestinal inflammation, and suggest that CAR activation may prove effective in enhancing mucosal healing in patients with IBD., (© 2017 The British Pharmacological Society.)

Giardia duodenalis is a prevalent cause of acute diarrheal disease worldwide. However, recent outbreaks in Italy and Norway have revealed a link between giardiasis and the subsequent development of chronic post-infectious irritable bowel syndrome. While the mechanisms underlying the causation of post-infectious irritable bowel syndrome remain obscure, recent findings suggest that alterations in gut microbiota communities are linked to the pathophysiology of irritable bowel syndrome. In the present study, we use a laboratory biofilm system to culture and enrich mucosal microbiota from human intestinal biopsies. Subsequently, we show that co-culture with Giardia induces disturbances in biofilm species composition and biofilm structure resulting in microbiota communities that are intrinsically dysbiotic - even after the clearance of Giardia. These microbiota abnormalities were mediated in part by secretory-excretory Giardia cysteine proteases. Using in vitro cell culture and germ-free murine infection models, we show that Giardia-induced disruptions of microbiota promote bacterial invasion, resulting in epithelial apoptosis, tight junctional disruption, and bacterial translocation across an intestinal epithelial barrier. Additionally, these dysbiotic microbiota communities resulted in increased activation of the Toll-like receptor 4 signalling pathway, and overproduction of the pro-inflammatory cytokine IL-1beta in humanized germ-free mice. Previous studies that have sought explanations and risk factors for the development of post-infectious irritable bowel syndrome have focused on features of enteropathogens and attributes of the infected host. We propose that polymicrobial interactions involving Giardia and gut microbiota may cause persistent dysbiosis, offering a new interpretation of the reasons why those afflicted with giardiasis are predisposed to gastrointestinal disorders post-infection., (Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Background and Aims: Non-alcoholic fatty liver disease is now the leading liver disease in North America. The progression of non-alcoholic fatty liver disease to the inflammatory condition, non-alcoholic steatohepatitis is complex and currently not well understood. Intestinal microbial dysbiosis has been implicated in the development of non-alcoholic fatty liver disease and progression of non-alcoholic steatohepatitis. Volatile organic compounds are byproducts of microbial metabolism in the gut that may enter portal circulation and have hepatotoxic effects contributing to the pathogenesis of non-alcoholic steatohepatitis. To test this hypothesis, we measured volatile organic compounds in cecal luminal contents and portal venous blood in a mouse model of non-alcoholic steatohepatitis., Methods: Gas chromatography-mass spectrometry analysis was conducted on cecal content and portal vein blood for volatile organic compound detection from mice fed a methionine and choline deficient diet, which induces non-alcoholic steatohepatitis. The colonic microbiome was studied by 16S rRNA gene amplification using the Illumina MiSeq platform., Results: Sixty-eight volatile organic compounds were detected in cecal luminal content, a subset of which was also present in portal venous blood. Importantly, differences in portal venous volatile organic compounds were associated with diet-induced steatohepatitis establishing a biochemical link between gut microbiota-derived volatile organic compounds and increased susceptibility to non-alcoholic steatohepatitis., Conclusion: Our model creates a novel tool to further study the role of gut-derived volatile organic compounds in the pathogenesis of non-alcoholic steatohepatitis., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Background: Evidence for the role of the gut microbiome in the pathogenesis of non-alcoholic fatty liver disease (NAFLD) is emerging. Strategies to manipulate the gut microbiota towards a healthier community structure are actively being investigated. Based on their ability to favorably modulate the gut microbiota, prebiotics may provide an inexpensive yet effective dietary treatment for NAFLD. Additionally, prebiotics have established benefits for glucose control and potentially weight control, both advantageous in managing fatty liver disease. Our objective is to evaluate the effects of prebiotic supplementation, adjunct to those achieved with diet-induced weight loss, on heptic injury and liver fat, the gut microbiota, inflammation, glucose tolerance, and satiety in patients with NAFLD., Methods/design: In a double blind, placebo controlled, parallel group study, adults (BMI ≥25) with confirmed NAFLD will be randomized to either a 16 g/d prebiotic supplemented group or isocaloric placebo group for 24 weeks (n = 30/group). All participants will receive individualized dietary counseling sessions with a registered dietitian to achieve 10 % weight loss. Primary outcome measures include change in hepatic injury (fibrosis and inflammation) and liver fat. Secondary outcomes include change in body composition, appetite and dietary adherence, glycemic and insulinemic responses and inflammatory cytokines. Mechanisms related to prebiotic-induced changes in gut microbiota (shot-gun sequencing) and their metabolic by-products (volatile organic compounds) and de novo lipogenesis (using deuterium incorporation) will also be investigated., Discussion: There are currently no medications or surgical procedures approved for the treatment of NAFLD and weight loss via lifestyle modification remains the cornerstone of current care recommendations. Given that prebiotics target multiple metabolic impairments associated with NAFLD, investigating their ability to modulate the gut microbiota and hepatic health in patients with NAFLD is warranted., Trial Registration: ClinicalTrials.gov (NCT02568605) Registered 30 September 2015.

Background & Aims: The inflammatory bowel diseases (IBDs) are chronic diseases that often require surgery. However, the risk of requirement of surgery over time has not been well characterized. We performed a systematic review and meta-analysis to establish the cumulative risk of surgery among patients with IBD and evaluated how this risk has changed over time., Methods: We searched Medline, EMBASE, PubMed, and conference proceedings (2009-2012) on May 8, 2013, for terms related to IBD and intestinal surgery. Two reviewers screened 8338 unique citations to identify 486 for full-text review. The analysis included population-based studies published as articles (n = 26) and abstracts (n = 4) that reported risks of surgery at 1, 5, or 10 years after a diagnosis of Crohn's disease and/or ulcerative colitis. The trend in risk of surgery over time was analyzed by meta-regression using mixed-effect models., Results: Based on all population-based studies, the risk of surgery 1, 5, and 10 years after diagnosis of Crohn's disease was 16.3% (95% confidence interval [CI], 11.4%-23.2%), 33.3% (95% CI, 26.3%-42.1%), and 46.6% (95% CI, 37.7%-57.7%), respectively. The risk of surgery 1, 5, and 10 years after diagnosis of ulcerative colitis was 4.9% (95% CI, 3.8%-6.3%), 11.6% (95% CI, 9.3%-14.4%), and 15.6% (95% CI, 12.5%-19.6%), respectively. The risk of surgery 1, 5, and 10 years after diagnosis of Crohn's disease and 1 and 10 years after diagnosis of ulcerative colitis has decreased significantly over the past 6 decades (P < .05)., Conclusions: Based on systematic review and meta-analysis of population-based studies, the risk of intestinal surgery among patients with IBD has decreased over the past 6 decades., (Copyright © 2013 AGA Institute. Published by Elsevier Inc. All rights reserved.)

Background & Aims: The histopathology of nonalcoholic fatty liver disease (NAFLD) is similar to that of alcoholic liver disease. Colonic bacteria are a source of many metabolic products, including ethanol and other volatile organic compounds (VOC) that may have toxic effects on the human host after intestinal absorption and delivery to the liver via the portal vein. Recent data suggest that the composition of the gut microbiota in obese human beings is different from that of healthy-weight individuals. The aim of this study was to compare the colonic microbiome and VOC metabolome of obese NAFLD patients (n = 30) with healthy controls (n = 30)., Methods: Multitag pyrosequencing was used to characterize the fecal microbiota. Fecal VOC profiles were measured by gas chromatography-mass spectrometry., Results: There were statistically significant differences in liver biochemistry and metabolic parameters in NAFLD. Deep sequencing of the fecal microbiome revealed over-representation of Lactobacillus species and selected members of phylum Firmicutes (Lachnospiraceae; genera, Dorea, Robinsoniella, and Roseburia) in NAFLD patients, which was statistically significant. One member of phylum Firmicutes was under-represented significantly in the fecal microbiome of NAFLD patients (Ruminococcaceae; genus, Oscillibacter). Fecal VOC profiles of the 2 patient groups were different, with a significant increase in fecal ester compounds observed in NAFLD patients., Conclusions: A significant increase in fecal ester VOC is associated with compositional shifts in the microbiome of obese NAFLD patients. These novel bacterial metabolomic and metagenomic factors are implicated in the etiology and complications of obesity., (Copyright © 2013 AGA Institute. Published by Elsevier Inc. All rights reserved.)

Background: Particulate matter (PM) is a key pollutant in ambient air that has been associated with negative health conditions in urban environments. The aim of this study was to examine the effects of orally administered PM on the gut microbiome and immune function under normal and inflammatory conditions., Methods: Wild-type 129/SvEv mice were gavaged with Ottawa urban PM10 (EHC-93) for 7-14 days and mucosal gene expression analyzed using Ingenuity Pathways software. Intestinal permeability was measured by lactulose/mannitol excretion in urine. At sacrifice, segments of small and large intestine were cultured and cytokine secretion measured. Splenocytes were isolated and incubated with PM10 for measurement of proliferation. Long-term effects of exposure (35 days) on intestinal cytokine expression were measured in wild-type and IL-10 deficient (IL-10(-/-)) mice. Microbial composition of stool samples was assessed using terminal restriction fragment length polymorphism. Short chain fatty acids were measured in caecum., Results: Short-term treatment of wild-type mice with PM10 altered immune gene expression, enhanced pro-inflammatory cytokine secretion in the small intestine, increased gut permeability, and induced hyporesponsiveness in splenocytes. Long-term treatment of wild-type and IL-10(-/-) mice increased pro-inflammatory cytokine expression in the colon and altered short chain fatty acid concentrations and microbial composition. IL-10(-/-) mice had increased disease as evidenced by enhanced histological damage., Conclusions: Ingestion of airborne particulate matter alters the gut microbiome and induces acute and chronic inflammatory responses in the intestine.

The Human Genome Project was completed a decade ago, leaving a legacy of process, tools, and infrastructure now being turned to the study of the microbes that reside in and on the human body as determinants of health and disease, and has been branded "The Human Microbiome Project." Of the various niches under investigation, the human gut houses the most complex and abundant microbial community and is an arena for important host-microbial interactions that have both local and systemic impact. Initial studies of the human microbiome have been largely descriptive, a testing ground for innovative molecular techniques and new hypotheses. Methods for studying the microbiome have quickly evolved from low-resolution surveys of microbial community structure to high-definition description of composition, function, and ecology. Next-generation sequencing technologies combined with advanced bioinformatics place us at the doorstep of revolutionary insight into the composition, capability, and activity of the human intestinal microbiome. Renewed efforts to cultivate previously "uncultivable" microbes will be important to the overall understanding of gut ecology. There remain numerous methodological challenges to the effective study and understanding of the gut microbiome, largely relating to study design, sample collection, and the number of predictor variables. Strategic collaboration of clinicians, microbiologists, molecular biologists, computational scientists, and bioinformaticians is the ideal paradigm for success in this field. Meaningful interpretation of the gut microbiome requires that host genetic and environmental influences be controlled or accounted for. Understanding the gut microbiome in healthy humans is a foundation for discovering its influence in various important gastrointestinal and nutritional diseases (eg, inflammatory bowel disease, diabetes, and obesity), and for rational translation to human health gains., (Copyright © 2012 Mosby, Inc. All rights reserved.)

Non-alcoholic fatty liver disease (NAFLD) and the more severe non-alcoholic steatohepatitis (NASH) represent a spectrum of diseases involving hepatic fat accumulation and histological features essentially identical to alcoholic liver disease; however, they occur in the absence of excessive alcohol intake. They typically arise in conjunction with one or more features of the metabolic syndrome. Lifestyle mediated weight loss remains the primary mode of therapy for NAFLD and NASH, but this is often ineffective and adjunctive medical and surgical treatments are presently lacking. Prebiotic fibres are a group of non-digestible carbohydrates that modulate the human microbiota in a manner that is advantageous to host health. Rodent studies suggest that dietary supplementation with prebiotic fibres positively impacts NAFLD by modifying the gut microbiota, reducing body fat, and improving glucoregulation. Future research should focus on placebo-controlled, human, clinical trials using histological endpoints to address the effects of prebiotics on NAFLD and NASH. The aim of this review is to summarize current knowledge about prebiotics as an emerging therapeutic target for NAFLD., (© 2011 John Wiley & Sons A/S.)

Background: Patients with Crohn's disease (CD) who smoke have a more complicated disease course., Aims: Our primary objective was to assess smoking related variables that were associated with smoking cessation versus continued smoking in patients with CD., Methods: A multi-center study identified CD patients who were seen at the University of Chicago and University of Calgary IBD clinics. Patients were categorized into three subgroups: lifetime non-smokers, current smokers, or ex-smokers. Participants completed questionnaires assessing their cigarette smoking behavior. Current smokers were prospectively followed for 6 months to assess smoking status and attempts to quit. Logistic regression analysis was performed to identify factors associated with smoking cessation., Results: Three hundred patients were enrolled with 148 identifying themselves as lifetime non-smokers, 70 as current smokers, and 82 as ex-smokers. Patients who reported their first cigarette within 5 min of waking were more likely to be current smokers (OR = 21; 95% CI 3.94-107.3) as compared to patients who waited greater than 60 min. Current smokers were more likely to have one or more household members who smoked compared to ex-smokers (P < 0.05). Nearly half (49%) of the current smokers were in the precontemplation stage of change (i.e. no intention to quit smoking). At the 6-month follow-up, only 11% reported they quit smoking., Conclusions: Patients who report a short time to first cigarette in the morning may have more difficulty in smoking cessation. Current smokers were more likely to have another smoker in the household compared to ex-smokers. Current smokers had low levels of motivation to quit smoking and consequently with no intervention, very few quit 6 months after the baseline assessment.

Background: Imbalances in gut luminal bacteria may contribute to the pathogenesis of irritable bowel syndrome (IBS)., Aim: To explore select bacteriological and anti-inflammatory effects of mesalazine (mesalamine; 5-aminosalicylic acid or 5ASA) and their relation to potential therapeutic effects in IBS., Methods: Prospective pilot study of 12 women with diarrhoea-predominant IBS. Patients received oral mesalazine (1.5 g b.d.) for 4 weeks followed by a 4-week washout phase. Molecular profiling of stool bacterial communities and IBS symptoms were assessed before, during and after mesalazine treatment. Colonic mucosal biopsies were assessed for proteolytic activity. Qualitative and quantitative effects of mesalazine on stool microbiota, mucosal proteolytic activity and IBS symptoms were assessed., Results: Faecal bacteria decreased by 46% on mesalazine treatment (P = 0.014), but returned to baseline during washout. Firmicutes and Bacteroidetes represented 95% of identified phylotypes, with a trend towards an increase in the proportion of Firmicutes at week 4 in symptomatic responders [median (IQR) 14% (49) increase] compared with nonresponders [median 5% (11) decrease, P = 0.088]. Rectosigmoid mucosal proteolytic activity did not change between baseline and treatment [median 23.2 (17.9) vs. 19.5 (46.7) mU activity/mg tissue, P = 0.433]. Eight of 12 (67%) patients responded favourably to mesalazine based on a global relief questionnaire, with significant decreases in days with discomfort and increases in bowel movement satisfaction., Conclusions: Mesalazine treatment is associated with a decrease in faecal bacteria abundance and rebalancing of the major constituents of the microbiota. Further study of the bacteriological and anti-inflammatory properties of mesalazine in IBS is warranted., (© 2011 Blackwell Publishing Ltd.)

Background: Attenuated innate immune responses to the intestinal microbiota have been linked to the pathogenesis of Crohn's disease (CD). Recent genetic studies have revealed that hypofunctional mutations of NLRP3, a member of the NOD-like receptor (NLR) superfamily, are associated with an increased risk of developing CD. NLRP3 is a key component of the inflammasome, an intracellular danger sensor of the innate immune system. When activated, the inflammasome triggers caspase-1-dependent processing of inflammatory mediators, such as IL-1β and IL-18., Methods: In the current study we sought to assess the role of the NLRP3 inflammasome in the maintenance of intestinal homeostasis through its regulation of innate protective processes. To investigate this role, Nlrp3(-/-) and wildtype mice were assessed in the dextran sulfate sodium and 2,4,6-trinitrobenzenesulfonic acid models of experimental colitis., Results: Nlrp3(-/-) mice were found to be more susceptible to experimental colitis, an observation that was associated with reduced IL-1β, reduced antiinflammatory cytokine IL-10, and reduced protective growth factor TGF-β. Macrophages isolated from Nlrp3(-/-) mice failed to respond to bacterial muramyl dipeptide. Furthermore, Nlrp3-deficient neutrophils exhibited reduced chemotaxis and enhanced spontaneous apoptosis, but no change in oxidative burst. Lastly, Nlrp3(-/-) mice displayed altered colonic β-defensin expression, reduced colonic antimicrobial secretions, and a unique intestinal microbiota., Conclusions: Our data confirm an essential role for the NLRP3 inflammasome in the regulation of intestinal homeostasis and provide biological insight into disease mechanisms associated with increased risk of CD in individuals with NLRP3 mutations., (Copyright © 2010 Crohn's & Colitis Foundation of America, Inc.)

The human gastrointestinal tract hosts a complex community of microorganisms that grow as biofilms on the intestinal mucosa. These bacterial communities are not well characterized, although they are known to play an important role in human health. This study aimed to develop a model for culturing biofilms (surface-adherent communities) of intestinal microbiota. The model utilizes adherent mucosal bacteria recovered from colonic biopsies to create multi-species biofilms. Culture on selective media and confocal microscopy indicated the biofilms were composed of a diverse community of bacteria. Molecular analyses confirmed that several phyla were represented in the model, and demonstrated stability of the community over 96 h when cultured in the device. This model is novel in its use of a multi-species community of mucosal bacteria grown in a biofilm mode of growth., (Copyright © 2010 Elsevier B.V. All rights reserved.)

Background: 5-Aminosalicylic acid (5-ASA) is a well-established treatment for inflammatory bowel disease (IBD) and may reduce the risk of colon cancer in patients with chronic colitis, but the mechanisms underlying these effects have not been fully elucidated. Although 5-ASA delivery is targeted to the distal gut, little is known about its effects on the luminal bacteria that reside there. Intestinal bacteria are believed play a role in causing or perpetuating IBD, and bioremediation has been studied as a therapeutic strategy. In an effort to better understand the bacteriological effects of 5-ASA, we examined the role of this compound at the level of bacterial gene expression., Methods: 5-ASA was screened for its effects on a random promoter library representing the genome of Salmonella enterica serovar Typhimurium as a model enteric bacterium. Forty-five constructs representing 38 unique promoters were found to be responsive to 5-ASA, and included genes involved in bacterial invasion, cellular metabolism, and stress resistance. Several genes of unknown function were also identified. These effects occurred at 5-ASA concentrations that are relevant to those achieved in the distal intestinal tract in patients with IBD but did not inhibit bacterial growth., Results: Bacterial invasiveness was decreased by 5-ASA. Some of the identified genes had homologs among commensal Gram-negative enteric bacteria., Conclusions: This study demonstrates that 5-ASA has potent effects on bacterial gene expression. These novel findings implicate intestinal bacteria as pharmacological targets of 5-ASA, perhaps contributing to the therapeutic action of this important class of IBD drugs.

The demonstration that immune and epithelial cells can discriminate between different microbial species has extended our understanding of the actions of probiotics beyond simple antimicrobial concepts. Several probiotic mechanisms of action, relative to inflammatory bowel disease, have been elucidated: (1) competitive exclusion, whereby probiotics compete with microbial pathogens; (2) immunomodulation and/or stimulation of an immune response; (3) antimicrobial activity and suppression of pathogen growth; (4) enhancement of barrier activity; and (5) induction of T cell apoptosis. The unraveling of these mechanisms of action has led to new support for the use of probiotics in the management of clinical inflammatory bowel disease. While level 1 evidence now supports the therapeutic use of some probiotics in the maintenance treatment of pouchitis, only level 2 and 3 evidence are currently available in support of the use of probiotics in the treatment of ulcerative colitis and Crohn's disease. Nevertheless, one significant and consistent finding has emerged over the course of research in the past year: not all probiotic bacteria have similar therapeutic effects. Rigorously designed, controlled clinical trials, to investigate the unresolved issues related to efficacy, dose, duration of use, single or multistrain formulation, and the concomitant use of prebiotics, synbiotics or antibiotics, are vital.

Objectives: Administering proton pump inhibitors (PPI) intravenously (iv) after endoscopic treatment of bleeding peptic ulcers reduces the incidence of rebleeding, the need for operative procedures, and hospitalizations. We assessed the cost implications of iv PPI initiated in all patients presenting to the emergency department (ED) with signs of upper gastrointestinal (UGI) bleeding., Methods: From a third-party payer perspective with a time horizon of 60 days, we built a decision analytic model comparing standard endoscopic therapy to a strategy in which all patients presenting to the ED with UGI bleeding would start iv PPI before endoscopy. After endoscopy, only those with peptic ulcers would be kept on iv PPI added to standard therapy. Probabilities of health events were extracted from published literature. Resource utilization profiles and costs (iv PPI, hospital stay for medical and operative procedures, and professional fees) were based on Medicare reimbursement data from a large hospital in Alabama. All costs were expressed in 2000 US dollars. Uncertainty was investigated through one-way sensitivity analyses and probabilistic analyses using Monte Carlo simulations., Results: In a hypothetical group of 1000 individuals, routine use of iv PPI prevented 40 rebleeds, 9 surgical procedures, and 223 hospital days, and led to incremental savings of dollars 920 per subject. Probabilistic sensitivity analyses indicated that the strategy of using iv PPI was likely to be dominant even when accounting for uncertainty., Conclusions: Based on available evidence, routine administration of iv PPI to all persons presenting with UGI bleeding represents good value for money and merits consideration as standard hospital policy.

Background: The administration of proton pump inhibitors intravenously after endoscopic treatment of peptic ulcers significantly reduces the recurrence of bleeding., Aim: To evaluate the incremental cost-effectiveness in Canada of intravenous proton pump inhibitor before endoscopic therapy to patients presenting with acute upper gastrointestinal bleeding, compared with endoscopic treatment alone., Methods: From a third-party payer perspective, we modelled the costs and effectiveness over 60 days of the two approaches using decision analysis. The probabilities of various outcomes, such as re-bleeding and the need for surgery, were taken from the published literature. We included the costs of intravenous proton pump inhibitor, therapeutic endoscopy, surgical procedures and hospitalizations, all expressed in 2001 Canadian dollars., Results: In a hypothetical cohort of 1000 patients, the intravenous proton pump inhibitor approach resulted in mean savings of 20,700 Canadian dollars with 37 re-bleeding episodes averted. The investigation of uncertainty resulted in a likelihood of intravenous proton pump inhibitor being cost-effective of at least 0.73., Conclusion: It is common in Canada to administer intravenous proton pump inhibitors to patients with upper gastrointestinal bleeding even before endoscopic confirmation of bleeding peptic ulcers. Our results suggest that this approach has a high likelihood of being cost-effective.

Neuropeptide Y (NPY) is a key factor in the neurochemical control of food intake, and obstructive cholestasis can be associated with disturbances in food intake. Our aim in this study was to determine whether obstructive cholestasis in the rat is associated with defective central responsiveness to NPY. Cholestasis was induced in rats by surgical bile duct resection. Rats with obstructive cholestasis exhibited a 20% reduction in food intake 2 days after laparotomy (compared with sham-resected controls) that had resolved by 4 days after surgery. Responsiveness to the orexigenic action of NPY was tested by measuring food intake after intracerebroventricular injection of NPY. In sham-resected rats, NPY infusion strikingly increased food intake, whereas bile duct-resected (BDR) rats showed a consistent significantly impaired feeding response to NPY at postlaparotomy days 2, 4, and 7. Separate experiments measured specific binding of [(3)H]NPY to hypothalamic receptors. Fos protein expression was measured in the hypothalamic paraventricular nucleus (PVN) as a marker of NPY-induced neuronal activation. The decreased orexigenic responsiveness to NPY was not caused by altered NPY binding at hypothalamic receptors or its ability to activate neurons in the PVN. Therefore, cholestatic rats demonstrate an attenuated NPY-induced orexigenic drive that occurs early after biliary obstruction, when cholestatic rats exhibit reduced food intake, and persists despite the return of food intake to normal levels and the presence of intact central NPY-related neuronal pathways.

Background/aims: Recently leptin, a protein released from adipocytes, has been identified as a potent circulating satiety factor. We therefore undertook this series of experiments to examine leptin's role in the anorexia associated with biliary obstruction., Methods: Rats underwent either surgical bile duct resection (BDR) or sham resection (sham). Body weight, and food and water intake were measured during a baseline period and for 8 days after surgery. At 4, 8 and 16 h as well as on days 2, 4, 6, and 8 postsurgery, sham and BDR rats were sacrificed and sera collected for subsequent measurement of leptin hormone concentration by RIA. White adipose tissue was collected on days 2, 4, 6 and 8 for leptin mRNA determination by Northern blot., Results: Obstructive cholestasis in BDR rats caused significant anorexia for up to 7 days post-surgery, whereas in sham rats, a significant decrease in food intake was only observed in the first 24-h period following surgery. In both sham and BDR rats, water intake was significantly decreased during the first 24-h period after surgery, but had recovered to baseline levels by day 2 in both groups. Fat pad mass corrected to body weight was not significantly different between the two experimental groups. Serum leptin levels were significantly increased 4 and 8 h after surgery, had normalized by 16 h post-surgery, and were then decreased in BDR rats on days 2, 4, 6 and 8 compared with controls. Leptin mRNA levels in epididymal fat pads were decreased by approximately 2-fold in BDR rats compared with sham rats on days 2, 4, 6 and 8. Furthermore, day 5 BDR and sham rats demonstrated similar anorectic responses to centrally administered leptin., Conclusions: Leptin production is significantly increased early after biliary obstruction but is reduced after prolonged biliary obstruction. Increased circulating leptin levels may contribute to the profound anorexia observed early after biliary obstruction but appear not to mediate the anorexia observed during more chronic biliary obstruction.

Background: By releasing pro-ulcerogenic mediators, mast cells may contribute to the mucosal injury associated with the use of nonsteroidal anti-inflammatory drugs (NSAIDs)., Methods: To study this, rat and mouse models of NSAID-induced gastric damage were used in which administration of indomethacin causes haemorrhagic injury in the corpus region of the stomach, and the "re-feeding" model in which penetrating antral ulcers are induced in the rat by naproxen. Mast cell degranulation was determined histologically and by measurement of tissue and serum levels of rat mast cell protease-II, a mediator specific to mucosal mast cells. The effects of either increasing or decreasing the number of gastric mucosal mast cells on the susceptibility of the stomach to injury induced by indomethacin were also studied., Results: Gastric injury induced by indomethacin was not accompanied by significant mast cell degranulation. Moreover, neither increasing nor decreasing the number of gastric mucosal mast cells had a significant effect on the susceptibility of the gastric mucosa to damage induced by indomethacin. In the re-feeding model, prior depletion of gastric mucosal mast cells did not significantly affect the severity of antral ulceration induced by naproxen, nor the ability of prostaglandin E2 to prevent this damage. Finally, indomethacin-induced damage was similar in severity in mice with a genetic defect resulting in the complete absence of mast cells as it was in normal, congenic littermates., Conclusion: Mast cells do not play a significant role in the development of gastric injury induced by acute NSAID administration in the rat or mouse.

Mast cells have been shown to play a role in many chronic inflammatory and fibrotic disorders. However, their possible contribution to the pathological changes that occur in liver cirrhosis is unknown. To explore this, we examined whether changes in hepatic mast cell number and mediator content were associated with fibrotic changes in experimental biliary cirrhosis. Rats were studied 7, 14, or 21 days after bile duct resection (BDR). Hepatic mast cells were identified by histochemical and immunohistochemical stains. Rat mast cell protease II (RMCP-II), a marker of mast cell degranulation, was measured in liver by enzyme-linked immunosorbent assay. Hepatic collagen deposition was assessed by Sirius Red F3BA staining. In day 21 BDR rats, there was a one- to twofold increase (P < .001) in the number of hepatic mast cells, but this was not observed in day 7 or 14 BDR rats. Mild fibrotic changes were noted in BDR rat livers as early as 7 days after induction of cholestasis. Significant expansion and organization of fibrous tissue had occurred in day 14 BDR rats which progressed to bridging fibrosis by day 21. Liver RMCP-II levels were decreased by 50 percent (P < .05) and mast cell degranulation was apparent as shown by histamine immunostaining. These results suggest that hepatic mast cell hyperplasia and degranulation occur during prolonged cholestasis in the rat. Although these changes do not correlate with the onset of hepatic fibrosis, they do occur at a time during which there is significant deposition and organization extracellular matrix elements. Hepatic mast cells, by releasing profibrogenic mediators, may contribute to fibrotic changes in biliary cirrhosis.

Several lines of evidence suggest a role for mast cells as modulators of gastric mucosal integrity, but the effect of antigenic mast cell activation on mucosal resistance to injury has not previously been examined. In this study, rats were sensitized to the nematode Nippostrongylus brasiliensis and were studied 35-42 days later. With use of an ex vivo gastric chamber preparation, the stomach was exposed for 10 min to 20% ethanol. In some rats, antigen was administered intra-arterially 10 min before application of ethanol. Sensitized rats exhibited similar levels of ethanol-induced gastric injury as control rats, despite having significantly greater numbers of mucosal mast cells. However, antigen administration, which did not in itself produce mucosal injury, significantly augmented (approximately 3-fold) the extent of injury in sensitized but not control rats. Prior treatment with dexamethasone depleted mucosal mast cells in control and sensitized rats. Moreover, this treatment abolished the increase in mucosal injury observed in sensitized rats treated with antigen and topical ethanol. Pretreatment with a leukotriene D4-receptor antagonist, but not a platelet-activating factor-receptor antagonist or a cyclooxygenase inhibitor, abolished the increased susceptibility of sensitized rats to gastric damage induced by antigen and topical ethanol. These results suggest that mucosal mast cell number per se does not influence mucosal susceptibility to injury; however, activation of mast cells markedly increases the susceptibility to injury through a peptidoleukotriene-dependent mechanism.

Hemoproteins have been suggested to contribute to various forms of tissue injury by catalyzing the peroxidation of lipids. In this study, the ability of hemoglobin to catalyze the production of a neutrophil-activating factor from arachidonic acid was examined. Incubation of arachidonic acid, hydrogen peroxide, and hemoglobin at 37 degrees C for 30 min resulted in the production of a lipid-extractable substance that was chemotactic for neutrophils in vitro and could stimulate leukocyte adherence in vivo. These actions could be inhibited by two leukotriene B4 (LTB4) receptor antagonists. The peroxidation product cross-reacted significantly with an antibody directed against LTB4, but not with an antibody directed against LTC4. The production of this factor was hemoprotein dependent. Immunoreactive LTB4 and biological activity were produced only when hemoglobin, or another hemoprotein, cytochrome c, was present in the reaction mixture. The amount of the factor produced could be increased in a concentration-dependent manner by increasing the amounts of arachidonic acid or hydrogen peroxide in the reaction mixture. The production of this factor could be inhibited by 5-aminosalicylic acid, catalase, or deferoxamine. Separation of the lipid-extractable products of the peroxidation of arachidonic acid on high-performance liquid chromatography revealed that the immunoreactive (with anti-LTB4) and chemotactic substance had a retention time distinct from that of LTB4 and the hydroxyeicosatetraenoic acids. A lipid-extractable substance with significant cross-reactivity to anti-LTB4 could also be produced if plasma was substituted for arachidonic acid in the reaction mixture.(ABSTRACT TRUNCATED AT 250 WORDS)

Biosynthesis of very long chain (>C(18)) fatty acids (VLCFAs) and the pathway for their incorporation into acyl lipids was studied in microspore-derived (MD) and zygotic embryos of Brassica napus L. cv Reston. In the presence of [1-(14)C]oleoyl-coenzyme A or [1-(14)C] eicosenoyl-coenzyme A, malonyl-coenzyme A, and reducing equivalents, maximal in vitro elongation activity was expressed in protein preparations from early-mid cotyledonary stage MD embryos (17-20 days in culture), when endogenous eicosenoic (20:1) and erucic (22:1) acids were just beginning to accumulate (approximately 1.5 milligrams per gram dry weight). The biosynthesis of VLCFAs and their incorporation into glycerolipids in vitro in the MD embryo system occurred at rates comparable to those measured in developing zygotic Reston embryos at about 20 days postanthesis. When glycerol-3-phosphate was supplied as acyl acceptor in time-course experiments using homogenates prepared from 18-day MD embryos, newly synthesized [(14)C]20:1 and [(14)C]22:1 were incorporated primarily into triacylglycerols (TAGs) and, to a lesser extent, into lyso-phosphatidic/phosphatidic acids, diacylglycerols, and phosphatidylcholines as well as the acyl-coenzyme A and free fatty acid pools. [(14)C]24:1 was not detected in any acyl lipid. Stereospecific analyses of the radiolabeled TAGs indicated that [(14)C]20:1 and [(14)C]22:1 moieties were esterified predominantly at the sn-3 position, but were also found at the sn-1 position. [(14)C]20:1, but not [(14)C]22:1, was detected at the sn-2 position. Similar patterns of (14)C-labeled VLCFA distribution were obtained in experiments conducted using a 15,000g pellet fraction from 18-day MD embryos. All trends observed in the formation of TAGs containing VLCFAs in the Reston MD embryo system were also confirmed in studies of zygotic embryos of the same cultivar. The data support the biosynthesis of 20:1 and then 22:1 via successive condensations of malonyl-coenzyme A with oleoyl-coenzyme A and, for the first time in B. napus, demonstrate the incorporation of newly synthesized VLCFAs into TAGs via the Kennedy pathway.