Vacuolating cytotoxin (vacA) alleles of Helicobacter pylori comprise two geographically widespread types, m1 and m2, and have evolved through limited recombination

Vacuolating cytotoxin (vacA) alleles of Helicobacter pylori vary, particularly in their mid region (which may be type m1 or m2) and their signal peptide coding region (type s1 or s2). We investigated nucleotide diversity among vacA alleles in strains from several locales in Asia, South America, and the USA. Phylogenetic analysis of vacA mid region sequences from 18 strains validated the division into two main groups (m1 and m2) and showed further significant divisions within these groups. Informative site analysis demonstrated one example of recombination between m1 and m2 alleles, and several examples of recombination among alleles within these groups. Recombination was not sufficiently extensive to destroy phylogenetic structure entirely. Synonymous nucleotide substitution rates were markedly different between regions of vacA, suggesting different evolutionary divergence times and implying horizontal transfer of genetic elements within vacA. Non-synonymous/synonymous rate ratios were greater between m1 and m2 sequences than among m1 sequences, consistent with m1 and m2 alleles encoding functions fitting strains for slightly different ecological niches

Helicobacter pylori infection and gastroduodenal diseases in Vietnam: a cross-sectional, hospital-based study

<p>Abstract</p> <p>Background</p> <p>The rate of <it>H. pylori </it>infection in Vietnam is reportedly high, but the spectrum of <it>H. pylori</it>-associated gastroduodenal diseases has not been systematically investigated. Moreover, despite the similarities of ethnicity and diet, the age-standardized incidence rate of gastric cancer in the northern city of Hanoi is higher than that in the southern city of Ho Chi Minh, but the reason for this phenomenon is unknown. The virulence of Vietnamese <it>H. pylori </it>has also not been investigated in detail.</p> <p>Methods</p> <p>Individuals undergoing esophagogastroduodenoscopy were randomly recruited. <it>H. pylori </it>infection status was determined based on the combined results of culture, histology, immunohistochemistry, rapid urine test and serum ELISA. Peptic ulcer (PU) and gastroesophageal reflux disease was diagnosed by endoscopy, and chronic gastritis was determined histologically. <it>H. pylori </it>virulence factors were investigated by PCR and sequencing.</p> <p>Results</p> <p>Among the examined patients, 65.6% were infected with <it>H. pylori</it>. The prevalence of infection was significantly higher in those over 40 years of age than in those aged ≤40. Chronic gastritis was present in all <it>H. pylori</it>-infected individuals, 83.1% of whom had active gastritis, and 85.3% and 14.7% had atrophy and intestinal metaplasia, respectively. PU was present in 21% of infected patients, whereas its incidence was very low in non-infected individuals. The prevalence of PU was significantly higher in Hanoi than in Ho Chi Minh. The prevalence of <it>vacA m1</it>, which has been identified as an independent risk factor for PU in Vietnam, was significantly higher among <it>H. pylori </it>isolates from Hanoi than among those from Ho Chi Minh.</p> <p>Conclusions</p> <p><it>H. pylori </it>infection is common in Vietnam and is strongly associated with PU, active gastritis, atrophy and intestinal metaplasia. <it>vacA m1 </it>is associated with an increased risk for PU and might contribute to the difference in the prevalence of PU and gastric cancer between Hanoi and Ho Chi Minh.</p

Non-performing loans at the dawn of IFRS 9: regulatory and accounting treatment of asset quality

Asset quality is a key indicator of sound banking. However, it is difficult for banking regulators and investors to assess it in the absence of a common, cross-border scheme to classify assets. Currently no standard is applied universally to categorise loans, the most sizeable asset on banks’ balance sheets. As a corollary, definitions of nonperforming loans (NPLs), despite recent steps towards greater harmonisation, continue to vary between jurisdictions. This paper offers a comprehensive analysis of NPLs and considers variations in the treatment of NPLs across countries, accounting regimes, and firms. The paper relies on a multi-disciplinary perspective and addresses legal, accounting, economic and strategic aspects of loan loss provisioning (LLP) and NPLs. A harmonised approach to NPL recognition is particularly desirable, in view of the fact that IFRS 9, the new accounting standard on loan loss provisioning, will be mandatory from January 2018. IFRS 9 changes the relationship between NPLs and provisions, by relying on greater judgement to determine provisions. The potential for divergence makes the need for comparable indicators against which to assess asset quality all the greater

Regulation of RKIP Function by Helicobacter pylori in Gastric Cancer

Helicobacter pylori (H. pylori) is a gram-negative, spiral-shaped bacterium that infects more than half of the world’s population and is a major cause of gastric adenocarcinoma. The mechanisms that link H. pylori infection to gastric carcinogenesis are not well understood. In the present study, we report that the Raf-kinase inhibitor protein (RKIP) has a role in the induction of apoptosis by H. pylori in gastric epithelial cells. Western blot and luciferase transcription reporter assays demonstrate that the pathogenicity island of H. pylori rapidly phosphorylates RKIP, which then localizes to the nucleus where it activates its own transcription and induces apoptosis. Forced overexpression of RKIP enhances apoptosis in H. pylori-infected cells, whereas RKIP RNA inhibition suppresses the induction of apoptosis by H. pylori infection. While inducing the phosphorylation of RKIP, H. pylori simultaneously targets non-phosphorylated RKIP for proteasome-mediated degradation. The increase in RKIP transcription and phosphorylation is abrogated by mutating RKIP serine 153 to valine, demonstrating that regulation of RKIP activity by H. pylori is dependent upon RKIP’s S153 residue. In addition, H. pylori infection increases the expression of Snail, a transcriptional repressor of RKIP. Our results suggest that H. pylori utilizes a tumor suppressor protein, RKIP, to promote apoptosis in gastric cancer cells

Helicobacter pylori (H pylori) infection in Greece: the changing prevalence during a ten-year period and its antigenic profile

BACKGROUND: To evaluate changes in H pylori infection prevalence in Greece during a ten-year period, and to examine its antigenic profile. METHODS: Three groups of patients were studied. Group O-87: Banked serum samples of 200 consecutive adult outpatients, from the Hepato-Gastroenterology clinic of a teaching hospital at Athens, collected in 1987. Group O-97: Serum samples of 201 similarly selected outpatients from the same Unit, collected in 1997. Group BD-97: Serum samples of 120 consecutive blood donors from the same hospital, collected in 1997. H pylori IgG antibody seroprevalence was studied by a quantitative ELISA. Antigenic profile was studied by western-blot IgG assay, in 62 IgG positive patients of O-97 and BD-97. Results were analyzed by conventional statistics and multivariate regression analysis. RESULTS: The H pylori seroprevalence increased with age in the three tested groups. In O-97, seroprevalence did not differ from that, in BD-97. On the contrary, there was a significant decrease in seropositivity between O-87 and O-97 (59.5% vs 49.2%, p = 0.039). Multiple regression analysis showed that age over 35 years (OR:3.45, 95% CI:1.59–7.49, p = 0.002) and year of patients' selection – that is 1987 or 1997 – (OR:1.73, 95% CI:1.14–2.65 for 1987, p = 0.010), were independent risk factors of H pylori infection. The seroprevalence of CagA+ and VacA+ strains was 77.4% and 58.5%, respectively, and type I(CagA+/VacA+) strains were significantly more common than type II(CagA-/VacA-) strains (59.7% vs 22.6%, p < 0.001). CONCLUSIONS: During a ten-year period, we found a significant decrease of H pylori infection in Greece and our data support the birth cohort phenomenon as an explanation for the age-dependent increase of H pylori infection. The prevalence of CagA and/or VacA positive strains is relatively high, in a country with low incidence of gastric cancer

Variations in Helicobacter pylori Cytotoxin-Associated Genes and Their Influence in Progression to Gastric Cancer: Implications for Prevention

Helicobacter pylori (HP) is a bacterium that colonizes the human stomach and can establish a long-term infection of the gastric mucosa. Persistent Hp infection often induces gastritis and is associated with the development of peptic ulcer disease, atrophic gastritis, and gastric adenocarcinoma. Virulent HP isolates harbor the cag (cytotoxin-associated genes) pathogenicity island (cagPAI), a 40 kb stretch of DNA that encodes components of a type IV secretion system (T4SS). This T4SS forms a pilus for the injection of virulence factors into host target cells, such as the CagA oncoprotein. We analyzed the genetic variability in cagA and other selected genes of the HP cagPAI (cagC, cagE, cagL, cagT, cagV and cag Gamma) using DNA extracted from frozen gastric biopsies or from clinical isolates. Study subjects were 95 cagA+ patients that were histologically diagnosed with chronic gastritis or gastric cancer in Venezuela and Mexico, areas with high prevalence of Hp infection. Sequencing reactions were carried out by both Sanger and next-generation pyrosequencing (454 Roche) methods. We found a total of 381 variants with unambiguous calls observed in at least 10% of the originally tested samples and reference strains. We compared the frequencies of these genetic variants between gastric cancer and chronic gastritis cases. Twenty-six SNPs (11 non-synonymous and 14 synonymous) showed statistically significant differences (P<0.05), and two SNPs, in position 1039 and 1041 of cagE, showed a highly significant association with cancer (p-value = 2.07×10−6), and the variant codon was located in the VirB3 homology domain of Agrobacterium. The results of this study may provide preliminary information to target antibiotic treatment to high-risk individuals, if effects of these variants are confirmed in further investigations

Confronting Uncertainty in Wildlife Management: Performance of Grizzly Bear Management

Scientific management of wildlife requires confronting the complexities of natural and social systems. Uncertainty poses a central problem. Whereas the importance of considering uncertainty has been widely discussed, studies of the effects of unaddressed uncertainty on real management systems have been rare. We examined the effects of outcome uncertainty and components of biological uncertainty on hunt management performance, illustrated with grizzly bears (Ursus arctos horribilis) in British Columbia, Canada. We found that both forms of uncertainty can have serious impacts on management performance. Outcome uncertainty alone – discrepancy between expected and realized mortality levels – led to excess mortality in 19% of cases (population-years) examined. Accounting for uncertainty around estimated biological parameters (i.e., biological uncertainty) revealed that excess mortality might have occurred in up to 70% of cases. We offer a general method for identifying targets for exploited species that incorporates uncertainty and maintains the probability of exceeding mortality limits below specified thresholds. Setting targets in our focal system using this method at thresholds of 25% and 5% probability of overmortality would require average target mortality reductions of 47% and 81%, respectively. Application of our transparent and generalizable framework to this or other systems could improve management performance in the presence of uncertainty. &nbsp

H. pylori Seropositivity before Age 40 and Subsequent Risk of Stomach Cancer: A Glimpse of the True Relationship?

Stomach carcinogenesis involves mucosal and luminal changes that favor spontaneous disappearance of Helicobacter pylori. Therefore, the association between the infection and cancer risk might typically be underestimated. As acquisition of the infection almost invariably occurs before adulthood, the serostatus at age 16–40 should best reflect the lifetime occurrence of the infection. We therefore conducted a case-control study nested within a historic cohort of about 400,000 individuals who donated sera before age 40 to either of two large Swedish Biobanks between 1968 and 2006, and whose records were linked to complete nationwide registers. For each stomach adenocarcinoma case occurring at least 5 years after serum donation 2 controls were selected matched on age, sex and year of donation and biobank. Serum immunoglobulin G antibodies against H. pylori cell-surface antigens (Hp-CSAs) were measured with an enzyme–linked immunosorbent assay and antibodies against CagA with an immunoblot assay. Conditional logistic regression models were used to estimate odds ratios (ORs) for stomach adenocarcinoma among H. pylori infected relative to uninfected. We confirmed 59 incident cases of stomach adenocarcinoma (41 non-cardia tumors) during follow-up. ORs for non-cardia stomach adenocarcinoma among subjects with Hp-CSA antibodies (regardless of CagA serostatus), antibodies against CagA (regardless of Hp-CSA serostatus), and antibodies to both, relative to those who were seronegative to both, were 17.1 (95% confidence interval [CI] 4.0–72.9), 10.9 (95% CI 3.2–36.9), and 48.5 (95% CI 5.8–407.4), respectively. H. pylori infection is a much stronger risk factor for non-cardia stomach adenocarcinoma than initially realized. However, further studies are needed to answer whether it is a necessary cause, as the possibility of misclassification of H. pylori status could not be ruled out in our study