Despite the decreasing prevalence of Helicobacter pylori infection among most of the Canadian population, it remains high among Aboriginals and recent immigrants. Given the health risks and complications associated with H pylori infection, measures aimed at eradicating H pylori are especially useful, particularly in vulnerable groups, and even more so if they lead to a reduction in the conditions that predispose individuals to gastric cancer. Following a brief discussion on the pathogenic role of H pylori, the prevalence and epidemiology of H pylori infection, and the associated health consequences, this article reviews a conference held by the Canadian Helicobacter Study Group in October 2010, which gathered a panel of experts in several fields to address the health risks of H pylori infection in at-risk populations and the potential benefits of adopting an eradication strategy.
The diminishing prevalence of Helicobacter pylori infection among most segments of the Canadian population has led to changes in the etiologies and patterns of associated upper gastrointestinal diseases, including fewer peptic ulcers and their complications. Canadian Aboriginals and recent immigrants are among populations in which the prevalence of H pylori infection remains high and, therefore, the health risks imposed by H pylori remain a significant concern. Population-based strategies for H pylori eradication in groups with a low prevalence of infection are unlikely to be cost effective, but such measures are attractive in groups in which the prevalence rates of infection remain substantial. In addition to a lower prevalence of peptic ulcers and dyspepsia, the public health value of eradication may be particularly important if this leads to a reduction in the prevalence of gastric cancer in high prevalence groups. Therefore The Canadian Helicobacter Study Group held a conference that brought together experts in the field to address these issues, the results of which are reviewed in the present article. Canadians with the highest prevalence of H pylori infection are an appropriate focus for considering the health advantages of eradicating persistent infection. In Canadian communities with a high prevalence of both H pylori and gastric cancer, there remains an opportunity to test the hypothesis that H pylori infection is a treatable risk factor for malignancy.
Gastric cancer; Helicobacter pylori; Immigrants; Native Canadians
Celiac disease (CD) is one of the most common diseases, resulting from both environmental (gluten) and genetic factors [human leukocyte antigen (HLA) and non-HLA genes]. The prevalence of CD has been estimated to approximate 0.5%-1% in different parts of the world. However, the population with diabetes, autoimmune disorder or relatives of CD individuals have even higher risk for the development of CD, at least in part, because of shared HLA typing. Gliadin gains access to the basal surface of the epithelium, and interact directly with the immune system, via both trans- and para-cellular routes. From a diagnostic perspective, symptoms may be viewed as either “typical” or “atypical”. In both positive serological screening results suggestive of CD, should lead to small bowel biopsy followed by a favourable clinical and serological response to the gluten-free diet (GFD) to confirm the diagnosis. Positive anti-tissue transglutaminase antibody or anti-endomysial antibody during the clinical course helps to confirm the diagnosis of CD because of their over 99% specificities when small bowel villous atrophy is present on biopsy. Currently, the only treatment available for CD individuals is a strict life-long GFD. A greater understanding of the pathogenesis of CD allows alternative future CD treatments to hydrolyse toxic gliadin peptide, prevent toxic gliadin peptide absorption, blockage of selective deamidation of specific glutamine residues by tissue, restore immune tolerance towards gluten, modulation of immune response to dietary gliadin, and restoration of intestinal architecture.
Celiac disease; Demography; Diagnosis; Pathogenesis; Treatment
The use of anti-tumor necrosis factor-α therapy for inflammatory bowel disease represents the most important advance in the care of these patients since the publication of the National Co-operative Crohn’s disease study thirty years ago. The recommendations of numerous consensus groups worldwide are now supported by a wealth of clinical trials and several meta-analyses. In general, it is suggested that tumor necrosis factor-α blockers (TNFBs) are indicated (1) for persons with moderately-severe Crohn’s disease or ulcerative colitis (UC) who have failed two or more causes of glucocorticosteroids and an acceptably long cause (8 wk to 12 wk) of an immune modulator such as azathioprine or methotrexate; (2) non-responsive perianal disease; and (3) severe UC not responding to a 3-d to 5-d course of steroids. Once TNFBs have been introduced and the patient is responsive, therapy given by the IV and SC rate must be continued. It remains open to definitive evidence if concomitant immune modulators are required with TNFB maintenance therapy, and when or if TNFB may be weaned and discontinued. The supportive evidence from a single study on the role of early versus later introduction of TNFB in the course of a patient’s illness needs to be confirmed. The risk/benefit profile of TNFB appears to be acceptable as long as the patient is immunized and tested for tuberculosis and viral hepatitis before the initiation of TNFB, and as long as the long-term adverse effects on the development of lymphoma and other tumors do not prone to be problematic. Because the rates of benefits to TNFB are modest from a population perspective and the cost of therapy is very high, the ultimate application of use of TNFBs will likely be established by cost/benefit studies.
Adalimumab; Adverse effects; Certolizumab pegol; Crohn's disease; Economic evaluation; Infliximab; Secondary lack of response; Ulcerative colitis
As is the case in all parts of gastroenterology and hepatology, there have been many advances in our knowledge and understanding of small intestinal diseases. Over 1000 publications were reviewed for 2008 and 2009, and the important advances in basic science as well as clinical applications were considered. In Part I of this Editorial Review, seven topics are considered: intestinal development; proliferation and repair; intestinal permeability; microbiotica, infectious diarrhea and probiotics; diarrhea; salt and water absorption; necrotizing enterocolitis; and immunology/allergy. These topics were chosen because of their importance to the practicing physician.
Diarrhea; Infectious diarrhea; Intestinal development; Intestinal proliferation and repair; Intestinal permeability; Microbiotica; Necrotizing enterocolitis; Probiotics
As is the case in all areas of gastroenterology and hepatology, in 2009 and 2010 there were many advances in our knowledge and understanding of small intestinal diseases. Over 1000 publications were reviewed, and the important advances in basic science as well as clinical applications were considered. In Part II we review six topics: absorption, short bowel syndrome, smooth muscle function and intestinal motility, tumors, diagnostic imaging, and cystic fibrosis.
Absorption; Cystic fibrosis; Diagnostic imaging; Intestinal motility; Short bowel syndrome; Smooth muscle function; Tumors
Gangliosides are integral to the structure and function of cell membranes. Ganglioside composition of the intestinal brush border and apical surface of the colon influences numerous cell processes including microbial attachment, cell division, differentiation, and signaling. Accelerated catabolism of ganglioside in intestinal disease results in increased proinflammatory signaling. Restoring proper structure and function to the diseased intestine can resolve inflammation, increase resistance to infection, and improve gut integrity to induce remission of conditions like necrotizing enterocolitis (NEC) and Crohn's disease (CD). Maintaining inactive state of disease may be achieved by reducing the rate that gangliosides are degraded or by increasing intake of dietary ganglioside. Collectively, the studies outlined in this paper indicate that the amount of gangliosides GM3 and GD3 in intestinal mucosa is decreased with inflammation, low level of GM3 is associated with higher production of proinflammatory signals, and ganglioside content of intestinal mucosa can be increased by dietary ganglioside.
The cost-effectiveness of initial strategies in managing Canadian patients with uninvestigated upper gastrointestinal symptoms remains controversial.
To assess the cost-effectiveness of six management approaches to uninvestigated upper gastrointestinal symptoms in the Canadian setting.
The present study analyzed data from four randomized trials assessing homogeneous and complementary populations of Canadian patients with uninvestigated upper gastrointestinal symptoms with comparable outcomes. Symptom-free months, quality-adjusted life-years (QALYs) and direct costs in Canadian dollars of two management approaches based on the Canadian Dyspepsia Working Group (CanDys) Clinical Management Tool, and four additional strategies (two empirical antisecretory agents, and two prompt endoscopy) were examined and compared. Prevalence data, probabilities, utilities and costs were included in a Markov model, while sensitivity analysis used Monte Carlo simulations. Incremental cost-effectiveness ratios and cost-effectiveness acceptability curves were determined.
Empirical omeprazole cost $226 per QALY ($49 per symptom-free month) per patient. CanDys omeprazole and endoscopy approaches were more effective than empirical omeprazole, but more costly. Alternatives using H2-receptor antagonists were less effective than those using a proton pump inhibitor. No significant differences were found for most incremental cost-effectiveness ratios. As willingness to pay (WTP) thresholds rose from $226 to $24,000 per QALY, empirical antisecretory approaches were less likely to be the most cost-effective choice, with CanDys omeprazole progressively becoming a more likely option. For WTP values ranging from $24,000 to $70,000 per QALY, the most clinically relevant range, CanDys omeprazole was the most cost-effective strategy (32% to 46% of the time), with prompt endoscopy-proton pump inhibitor favoured at higher WTP values.
Although no strategy was the indisputable cost-effective option, CanDys omeprazole may be the strategy of choice over a clinically relevant range of WTP assumptions in the initial management of Canadian patients with uninvestigated dyspepsia.
Antisecretory therapy; Cost-effectiveness; Dyspepsia; Economic modelling; Endoscopy; Helicobacter pylori
Celiac disease now affects about one person in a hundred in Europe and North America. In this review, we consider a number of important and exciting recent developments, such as clinical associations, HLA-DQ2 and HLA-DQ8 predispositions, the concept of potential celiac disease, the use of new imaging/endoscopy techniques, and the development of refractory disease. This review will be of use to all internists, pediatricians and gastroenterologists.
Inflammation; Infection; Malabsorption; Pathophysiology; Physiology
The proton pump inhibitors (PPIs) as a class are remarkably safe and effective for persons with peptic ulcer disorders. Serious adverse events are extremely rare for PPIs, with case reports of interstitial nephritis with omeprazole, hepatitis with omeprazole and lansoprazole, and disputed visual disturbances with pantoprazole and omeprazole. PPI use is associated with the development of fundic gland polyps (FGP); stopping PPIs is associated with regression of FGP. In the absence of Helicobacter pylori infection, the long-term use of PPIs has not been convincingly proven to cause or be associated with the progression of pre-existing chronic gastritis or gastric atrophy or intestinal metaplasia. Mild/modest hypergastrinemia is a physiological response to the reduction in gastric acid secretion due to any cause. The long-term use of PPIs has not been convincingly proven to cause enterochromaffin-like cell hyperplasia or carcinoid tumors. PPIs increase the risk of community acquired pneumonia, but not of hospital acquired (nosocomial) pneumonia. There is no data to support particular care in prescribing PPI therapy due to concerns about risk of hip fracture with the long-term use of PPIs. Long-term use of PPIs does not lead to vitamin B12 deficiencies, except possibly in the elderly, or in persons with Zollinger-Ellison Syndrome who are on high doses of PPI for prolonged periods of time. There is no convincingly proven data that PPIs increase the risk of Clostridium difficile-associated diarrhea in persons in the community. The discontinuation of PPIs may result in rebound symptoms requiring further and even continuous PPI use for suppression of symptoms. As with all medications, the key is to use PPIs only when clearly indicated, and to reassess continued use so that long-term therapy is used judiciously. Thus, in summary, the PPIs are a safe class of medications to use long-term in persons in whom there is a clear need for the maintenance of extensive acid inhibition.
Acid inhibition; Drug safety; Osteoporosis; Pneumonia; Enteric infections
Throughout our lifetime, the intestine changes. Some alterations in its form and function may be genetically determined, and some are the result of adaptation to diet, temperature, or stress. The critical period programming of the intestine can be modified, such as from subtle differences in the types and ratios of n3:m6 fatty acids in the diet of the pregnant mother, or in the diet of the weanlings. This early forced adaptation may persist in later life, such as the unwanted increased intestinal absorption of sugars, fatty acids and cholesterol. Thus, the ontogeny, early growth and development of the intestine is important for the adult gastroenterologist to appreciate, because of the potential for these early life events to affect the responsiveness of the intestine to physiological or pathological challenges in later life.
Intestinal development; Ontogeny; Pediatrics
The process of intestinal adaptation (“enteroplasticity”) is complex and multifaceted. Although a number of trophic nutrients and non-nutritive factors have been identified in animal studies, successful, reproducible clinical trials in humans are awaited. Understanding mechanisms underlying this adaptive process may direct research toward strategies that maximize intestinal function and impart a true clinical benefit to patients with short bowel syndrome, or to persons in whom nutrient absorption needs to be maximized. In this review, we consider the morphological, kinetic and membrane biochemical aspects of enteroplasticity, focus on the importance of nutritional factors, provide an overview of the many hormones that may alter the adaptive process, and consider some of the possible molecular profiles. While most of the data is derived from rodent studies, wherever possible, the results of human studies of intestinal enteroplasticity are provided.
Diabetes; Diet; Hormonal regulation; Intestinal resection; Mechanisms; Morphology; Nutrient absorption; Short bowel syndrome; Signals
There are various hormones and growth factors which may modify the intestinal absorption of nutrients, and which might thereby be useful in a therapeutic setting, such as in persons with short bowel syndrome. In partI, we focus first on insulin-like growth factors, epidermal and transferring growth factors, thyroid hormones and glucocorticosteroids. Part II will detail the effects of glucagon-like peptide (GLP)-2 on intestinal absorption and adaptation, and the potential for an additive effect of GLP2 plus steroids.
Epidermal growth factor; Glucocortico-steroids; Insulin-like growth factor-I/II; Intestinal growth; Transforming growth factor-α-2; Hepatocyte growth factor; Keratinocyte growth factor
Using high sucrose-fed male Sprague-Dawley rats, a study was conducted to determine the effects of feeding Galactomannan (GAL), a soluble dietary fiber extracted from Canadian-grown fenugreek seeds, on blood lipid and glucose responses. Rats (n = 8, 175–200 g) were randomly assigned to one of three high sucrose diets containing 10% cellulose (control), 7.5% cellulose + 2.5% GAL, and 5% cellulose + 5% GAL, respectively for 4 weeks. After 3 weeks, an oral glucose tolerance test (OGTT) was performed on each rat. A week later blood samples were collected to determine the effect on blood lipids. A significant reduction in glycemic response was observed only in 5% GAL group at 120 min following OGTT, when compared with that of control and 2.5% GAL groups. The plasma level of insulin was also significantly reduced (p<0.001) in 5% GAL-fed rats but at all times during OGTT. These animals also showed a reduction in body weight gain (p<0.05) in parallel with less food intake (p<0.05). All GAL-fed (2.5% and 5.0%) rats had significantly reduced plasma levels of triglycerides and total cholesterol in association with a reduction in epididymal adipose weight. Overall, this study demonstrated that feeding GAL from Canadian-grown fenugreek seeds has the potential to alter glycemic and lipidemic status and reduce abdominal fat in normal rats.
Canadian fenugreek seed; galactomannan; glycemic status; lipidemic status; epididymal tissue
Necrotizing enterocolitis is an inflammatory bowel disease of neonates with significant morbidity and mortality in preterm infants. Due to the multifactorial nature of the disease and limitations in disease models, early diagnosis remains challenging and the pathogenesis elusive. Although preterm birth, hypoxic-ischemic events, formula feeding, and abnormal bacteria colonization are established risk factors, the role of genetics and vasoactive/inflammatory mediators is unclear. Consequently, treatments do not target the specific underlying disease processes and are symptomatic and surgically invasive. Breast-feeding is the most effective preventative measure. Recent advances in the prevention of necrotizing enterocolitis have focused on bioactive nutrients and trophic factors in human milk. Development of new disease models including the aspect of prematurity that consistently predisposes neonates to the disease with multiple risk factors will improve our understanding of the pathogenesis and lead to discovery of innovative therapeutics.
Necrotizing enterocolitis; Diagnosis; Pathogenesis; Prevention; Disease models; Vasoactive/inflammatory mediators
Dermatopontin (DPT) is an abundant component of the stromal extracellular matrix; however, its function in the cornea is poorly understood. This study was conducted to determine whether DPT has a direct role in corneal matrix organization by investigating the ultrastructure of Dpt-null (Dpt−/−) mouse corneas.
Conventional light microscopy was used to compare the corneal thickness of Dpt−/− mice with that of the wild type. Collagen fibril distribution was studied using transmission electron microscopy and the datasets analyzed using image analysis software to determine fibrillar volume, fibril diameter, and spacing.
Light microscopy demonstrated that Dpt−/− corneas in 2-month-old mice showed a 24% reduction in average stromal thickness compared with wild type (P < 0.001). The epithelium and Descemet's membrane appeared normal. Examination of Dpt−/− stroma by transmission electron microscopy indicated significant disruption of fibril spacing within the posterior lamellae, whereas the mid and anterior regions appeared largely unaffected compared with wild type. The collagen fibrils in Dpt−/− stroma showed a lower fibril volume fraction and a pronounced change in posterior fibrillar organization. There was no apparent difference in fibril diameter between Dpt−/− and wild-type mice.
Collectively, these data suggest that DPT plays a key role in collagen fibril organization. The defects in collagen organization in Dpt−/− cornea appear to be most severe in the posterior stroma. It is possible that DPT interacts with corneal proteoglycans and that this interaction is involved in the maintenance of stromal architecture.
We evaluated the effect of medically induced symptomatic disease improvement on in vitro tests of cell-mediated immune responses in 33 patients with Crohn's disease. When results obtained in 17 patients with ulcerative colitis were compared with those of 10 patients with ulcerative colitis who had undergone a colectomy, no significant correlation was detected between individual clinical and laboratory variables or the Crohn's disease activity index and in vitro tests of cell-mediated immunity. A different pattern emerged from the longitudinal tests of cell-mediated immunity: when these test results were initially abnormal in patients with Crohn's disease, clinical improvement as assessed by the Crohn's disease activity index was associated with normalizing cell-mediated immunity. In contrast, when the test results were initially normal, clinical improvement was not associated with any change in the immune response. Following colectomy in patients with ulcerative colitis, some abnormalities of suppressed immune responses remained, although patients were cured of their disease. Factors other than clinical disease activity may be responsible for the suppressed immunoresponsiveness in some patients with inflammatory bowel disease, and variable changes in cell-mediated immunity occur after both surgical and medical treatment.
In a Canadian multicenter trial, a new dosing regimen of cimetidine (Tagamet)—600 mg given twice a day—was compared with the standard regimen of 300 mg four times a day in 118 evaluable patients with endoscopically proved esophagitis. More than 90% of the patients evaluated had clinically moderate to severe esophagitis. After four weeks of therapy, both regimens had significantly reduced the number of episodes and the severity and duration of the worst episodes of daytime and nighttime heartburn, as evaluated by visual analogue scales. After eight weeks of therapy, this improvement persisted. There was no difference between the regimens. Healing was observed endoscopically in 57% of patients receiving cimetidine 300 mg four times a day and in 55% of those receiving 600 mg twice a day. Side effects were infrequent and minor.