This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Objectives:The incidence of pediatric-onset inflammatory bowel disease (IBD) is increasing worldwide. We used population-based health administrative data to determine national Canadian IBD incidence, prevalence, and trends over time of childhood-onset IBD.Methods:We identified children <16 years (y) diagnosed with IBD 1999–2010 from health administrative data in five provinces (Alberta, Manitoba, Nova Scotia, Ontario, Quebec), comprising 79.2% of the Canadian population. Standardized incidence and prevalence were calculated per 100,000 children. Annual percentage change (APC) in incidence and prevalence were determined using Poisson regression analysis. Provincial estimates were meta-analyzed using random-effects models to produce national estimates.Results:5,214 incident cases were diagnosed during the study period (3,462 Crohn’s disease, 1,382 ulcerative colitis, 279 type unclassifiable). The incidence in Canada was 9.68 (95% CI 9.11 to 10.25) per 100,000 children. Incidence was similar amongst most provinces, but higher in Nova Scotia. APC in incidence did not significantly change over the study period in the overall cohort (+2.06%, 95% CI −0.64% to +4.76%). However, incidence significantly increased in children aged 0–5y (+7.19%, 95% +2.82% to +11.56%). Prevalence at the end of the study period in Canada was 38.25 (95% CI 35.78 to 40.73) per 100,000 children. Prevalence increased significantly over time, APC +4.56% (95% CI +3.71% to +5.42%).Conclusions:Canada has amongst the highest incidence of childhood-onset IBD in the world. Prevalence significantly increased over time. Incidence was not statistically changed with the exception of a rapid increase in incidence in the youngest group of children.

BACKGROUND & AIMS: Inflammatory bowel diseases (IBDs) exist worldwide, with high prevalence in North America. IBD is complex and costly, and its increasing prevalence places a greater stress on health care systems. We aimed to determine the past current, and future prevalences of IBD in Canada. METHODS: We performed a retrospective cohort study using population-based health administrative

Many studies have shown that genetic susceptibility plays a key role in determining whether bacterial pathogens successfully infect and cause disease in potential hosts. Surprisingly, whether host genetics influence the pathogenesis of attaching and effacing (A/E) bacteria such as enteropathogenic and enterohemorrhagic Escherichia coli has not been examined. To address this issue, we infected various mouse strains with Citrobacter rodentium, a member of the A/E pathogen family. Of the strains tested, the lipopolysaccharide (LPS) nonresponder C3H/HeJ mouse strain experienced more rapid and extensive bacterial colonization than did other strains. Moreover, the high bacterial load in these mice was associated with accelerated crypt hyperplasia, mucosal ulceration, and bleeding, together with very high mortality rates. Interestingly, the basis for the increased susceptibility was not due to LPS hyporesponsiveness, as the genetically related but LPS-responsive C3H/HeOuJ and C3H/HeN mouse strains were also susceptible to infection. Analysis of the intestinal pathology in these susceptible strains revealed significant crypt epithelial cell apoptosis (terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end label staining) as well as bacterial translocation to the mesenteric lymph nodes. Further studies with infection of SCID (T-and B-lymphocyte-deficient) C3H/HeJ mice demonstrated that loss of lymphocytes had no effect on bacterial numbers but did reduce crypt cell apoptosis and delayed mortality. These studies thus identify the adaptive immune system, crypt cell apoptosis, and bacterial translocation but not LPS responsiveness as contributing to the tissue pathology and mortality seen during C. rodentium infection of highly susceptible mouse strains. Determining the basis for these strains' susceptibility to intestinal colonization by an A/E pathogen will be the focus of future studies.

BACKGROUND: Adolescents with irritable bowel syndrome (IBS) frequently experience interference with everyday activities. Mind-body approaches such as yoga have been recommended as interventions for patients with IBS. Despite promising results among adult samples, there have been limited studies exploring the efficacy of yoga with pediatric patients.OBJECTIVE: To conduct a preliminary randomized study of yoga as treatment for adolescents with IBS.METHODS: Twenty-five adolescents aged 11 to 18 years with IBS were randomly assigned to either a yoga or wait list control group. Before the intervention, both groups completed questionnaires assessing gastrointestinal symptoms, pain, functional disability, coping, anxiety and depression. The yoga intervention consisted of a 1 h instructional session, demonstration and practice, followed by four weeks of daily home practice guided by a video. After four weeks, adolescents repeated the baseline questionnaires. The wait list control group then received the yoga intervention and four weeks later completed an additional set of questionnaires.RESULTS: Adolescents in the yoga group reported lower levels of functional disability, less use of emotion-focused avoidance and lower anxiety following the intervention than adolescents in the control group. When the pre- and postintervention data for the two groups were combined, adolescents had significantly lower scores for gastrointestinal symptoms and emotion-focused avoidance following the yoga intervention. Adolescents found the yoga to be helpful and indicated they would continue to use it to manage their IBS.CONCLUSIONS: Yoga holds promise as an intervention for adolescents with IBS.

These data suggest a significantly higher incidence of IBD in the South Asian pediatric population compared with the rest of the BC pediatric population, with a different pattern of phenotypic expression, a male predominance, and more extensive colonic disease. These data suggest a potential effect of migration, and environmental and lifestyle change on the incidence of IBD and disease subtype.

Citrobacter rodentium belongs to the attaching and effacing family of enteric bacterial pathogens that includes both enteropathogenic and enterohemorrhagic Escherichia coli. These bacteria infect their hosts by colonizing the intestinal mucosal surface and intimately attaching to underlying epithelial cells. The abilities of these pathogens to exploit the cytoskeleton and signaling pathways of host cells are well documented, but their interactions with the host's antimicrobial defenses, such as inducible nitric oxide synthase (iNOS), are poorly understood. To address this issue, we infected mice with C. rodentium and found that iNOS mRNA expression in the colon significantly increased during infection. Immunostaining identified epithelial cells as the major source for immunoreactive iNOS. Finding that nitric oxide (NO) donors were bacteriostatic for C. rodentium in vitro, we examined whether iNOS expression contributed to host defense by infecting iNOS-deficient mice. Loss of iNOS expression caused a small but significant delay in bacterial clearance without affecting tissue pathology. Finally, immunofluorescence staining was used to determine if iNOS expression was localized to infected cells by staining for the C. rodentium virulence factor, translocated intimin receptor (Tir), as well as iNOS. Interestingly, while more than 85% of uninfected epithelial cells expressed iNOS, fewer than 15% of infected (Tir-positive) cells expressed detectable iNOS. These results demonstrate that both iNOS and intestinal epithelial cells play an active role in host defense during C. rodentium infection. However, the selective expression of iNOS by uninfected but not infected cells suggests that this pathogen has developed mechanisms to locally limit its exposure to host-derived NO.

SummaryEnteropathogenic Escherichia coli (EPEC) and enterohaemorrhagic E. coli are non-invasive attaching/effacing (A/E) bacterial pathogens that infect their host's intestinal epithelium, causing severe diarrhoeal disease. These bacteria utilize a type III secretion apparatus to deliver effector molecules into host cells, subverting cellular function. Mitochondrial associated protein (Map) is a multifunctional effector protein that targets host cell mitochondria and contributes to infection-induced epithelial barrier dysfunction in vitro . Unfortunately, the relevance of these actions to the pathogenesis of EPEC-induced disease is uncertain. Using Citrobacter rodentium, a mouseadapted A/E bacterium, we found that Map colocalized with host cell mitochondria, and that in vivo infection led to a disruption of mitochondrial morphology in infected colonocytes as assessed by electron microscopy. Histochemical staining for the mitochondrial enzyme succinate dehydrogenase also revealed a significant loss of mitochondrial respiratory function in the infected intestinal epithelium; however, both pathologies were attenuated in mice infected with a D map strain. C. rodentium Map was also implicated in the disruption of epithelial barrier function both in vitro and in vivo . These studies thus advance our understanding of how A/E pathogens subvert host cell functions and cause disease, demonstrating that Map contributes to the functional disruption of the intestinal epithelium during enteric infection by C. rodentium .