Long-term follow-up of the incidence of Helicobacter pylori.

OBJECTIVES: Helicobacter pylori causes peptic ulcer disease and gastric cancer. Understanding the incidence of H. pylori could help guide research on potential infection prevention strategies. Previous studies indicate infection occurs in young children, but the risk of infection in older children and adolescents is unclear. Our hypothesis was that H. pylori infection is rare in adolescence or adulthood. Our aim was to determine the incidence of H. pylori over a prolonged follow-up in a cohort of 626 noninfected individuals. METHODS: Participants, including index children, mothers, fathers and siblings, from a previous study (1997-2002) were traced, and 883 of 946 participated in this extended follow-up. We used the 13C urea breath test (13C-UBT) to determine the incidence of H. pylori among 626 family members not infected in 2002, including 75 younger siblings who were not born or too young for testing in 2002. RESULTS: Eight (3.8%) of 210 index participants (mean ± standard deviation age 17.92 ± 0.77 years) became infected during 11.07 ± 0.56 years of follow-up (incidence, 3.42 per 1000 person-years; 95% confidence interval (CI), 1.48-6.74). Only one (0.6%) of 165 older siblings became infected (incidence, 0.57 per 1000 person-years; 95% CI, 0.007-3.16) and one of 176 parents became infected (incidence, 0.63 per 1000 person-years; 95% CI, 0.01-3.5). Of 75 younger siblings (age 10.9 ± 2.85 years) who were too young for testing or not yet born in 2002, nine (12%) became infected (incidence, 11.32 per 1000 person-years; 95% CI, 5.27-21.49). The highest incidence of H. pylori infection was in those born after 2005. CONCLUSIONS: The incidence of H. pylori was extremely low in older children and adults in developed countries. Spontaneous clearance of infection was uncommon in our study population.

Prioritizing genomic applications for action by level of evidence: a horizon-scanning method.

As evidence accumulates on the use of genomic tests and other health-related applications of genomic technologies, decision makers may increasingly seek support in identifying which applications have sufficiently robust evidence to suggest they might be considered for action. As an interim working process to provide such support, we developed a horizon-scanning method that assigns genomic applications to tiers defined by availability of synthesized evidence. We illustrate an application of the method to pharmacogenomics tests.

Phenopedia and Genopedia: disease-centered and gene-centered views of the evolving knowledge of human genetic associations.

SUMMARY: We developed web-based applications that encourage the exploration of the literature on human genetic associations by using a database that is continuously updated from PubMed. These applications provide user-friendly interfaces for searching summarized information on human genetic associations, using either genes or diseases as the starting point. AVAILABILITY: Phenopedia and Genopedia can be freely accessed at http://www.hugenavigator.net/HuGENavigator/startPagePhenoPedia.do and http://www.hugenavigator.net/HuGENavigator/startPagePedia.do, respectively.

Campylobacter jejuni cocultured with epithelial cells reduces surface capsular polysaccharide expression.

The host cell environment can alter bacterial pathogenicity. We employed a combination of cellular and molecular techniques to study the expression of Campylobacter jejuni polysaccharides cocultured with HCT-8 epithelial cells. After two passages, the amount of membrane-bound high-molecular-weight polysaccharide was considerably reduced. Microarray profiling confirmed significant downregulation of capsular polysaccharide (CPS) locus genes. Experiments using conditioned media showed that sugar depletion occurred only when the bacterial and epithelial cells were cocultured. CPS depletion occurred when C. jejuni organisms were exposed to conditioned media from a different C. jejuni strain but not when exposed to conditioned media from other bacterial species. Proteinase K or heat treatment of conditioned media under coculture conditions abrogated the effect on the sugars, as did formaldehyde fixation and cycloheximide treatment of host cells or chloramphenicol treatment of the bacteria. However, sugar depletion was not affected in flagellar export (fliQ) and quorum-sensing (luxS) gene mutants. Passaged C. jejuni showed reduced invasiveness and increased serum sensitivity in vitro. C. jejuni alters its surface polysaccharides when cocultured with epithelial cells, suggesting the existence of a cross talk mechanism that modulates CPS expression during infection.

Trends in pharmacogenomic epidemiology: 2001-2007.

BACKGROUND: Pharmacogenomic epidemiology (PGxE) assesses the range of responses to pharmacologic agents in relation to genetic variation in population groups. We analyzed publication trends to describe the emerging field of PGxE. METHODS: We analyzed PGxE literature published from 2001 to 2007 by using the HuGE Navigator, a curated database of abstracts on human genome epidemiology extracted from PubMed. We summarized trends by gene and study design and, for the 4 most cited genes, by associated health outcomes and drugs. RESULTS: In all, 1,855 PGxE articles were indexed from 2001 through 2007, with annual publications increasing more than 15-fold during this period. Observational studies outnumbered clinical trials by a ratio of 10 to 1 (1,660 vs. 178). Just 4 genes together accounted for nearly one-fifth of all publications: ABCB1, CYP2C9, CYP2C19, and CYP2D6. For these 4 genes, the most frequently cited therapeutic category was antineoplastic agent, followed by anticoagulant, antiulcer, and antidepressant. Warfarin was the single most frequently cited drug. CONCLUSIONS: The field of PGxE is growing rapidly, encompassing a large spectrum of diseases and drugs important in clinical practice. Systematic tracking and synthesis of the published literature in PGxE can help identify promising applications and guide translation research.

The G67E mutation in hMLH1 is associated with an unusual presentation of Lynch syndrome.

Germline mutations in the mismatch repair (MMR) genes are associated with Lynch syndrome, also known as hereditary non-polyposis colorectal cancer (HNPCC) syndrome. Here, we characterise a variant of hMLH1 that confers a loss-of-function MMR phenotype. The mutation changes the highly conserved Gly67 residue to a glutamate (G67E) and is reminiscent of the hMLH1-p.Gly67Arg mutation, which is present in several Lynch syndrome cohorts. hMLH1-Gly67Arg has previously been shown to confer loss-of-function (Shimodaira et al, 1998), and two functional assays suggest that the hMLH1-Gly67Glu protein fails to sustain normal MMR functions. In the first assay, hMLH1-Gly67Glu abolishes the protein's ability to interfere with MMR in yeast. In the second assay, mutation of the analogous residue in yMLH1 (yMLH1-Gly64Glu) causes a loss-of-function mutator phenotype similar to yMLH1-Gly64Arg. Despite these molecular similarities, an unusual spectrum of tumours is associated with hMLH1-Gly67Glu, which is not typical of those associated with Lynch syndrome and differs from those found in families carrying the hMLH1-Gly67Arg allele. This suggests that hMLH1 may have different functions in certain tissues and/or that additional factors may modify the influence of hMLH1 mutations in causing Lynch syndrome.

Public health impact of genetic tests at the end of the 20th century.

PURPOSE: To evaluate genetics tests available for clinical, research, and public health purposes in terms of their public health impact as measured by the number of people who could potentially be tested. METHODS: Genetic tests for the 751 inherited diseases or conditions listed in the GeneTests database as of November 2000, were classified on the basis of their use for population-based testing and the prevalence of the disease or condition being tested. The GeneTests database divides the tests into two groups: those offered for clinical use and those available for research only. RESULTS: Of the 423 clinical tests, 51 had potentially greater impact on public health because of their use in statewide newborn screening programs, other population screening programs, or testing for common diseases with a prevalence over 1 in 2,000 people. Among the 328 tests performed for research purposes only, 18 met the criteria for potentially greater public health impact. CONCLUSIONS: Our classification scheme indicated that fewer than 10% of the genetic tests listed in the GeneTests database at the end of 2000 are highly relevant to public health. The majority of genetic tests are used in diagnosis and/or genetic counseling for rare, single-gene disorders in a limited number of people. However, as more tests are being considered for newborn screening, and associations between genes and common diseases are being discovered, the impact of genetic testing on public health is likely to increase.

Antigastric autoantibodies in ferrets naturally infected with Helicobacter mustelae.

Infection with Helicobacter pylori has been associated with induction of autoantibodies that cross-react with the gastric mucosa. There have been discordant reports as to whether or not these autoantibodies arise due to molecular mimicry between H. pylori and host cell antigens on parietal cells. In this study, we investigated whether molecular mimicry by H. mustelae causes autoantibodies in infected ferrets. Serum from H. mustelae-infected ferrets reacted with parietal cells in the ferret gastric mucosa but not with duodenal or colonic mucosa. These sera did not react with the blood group A epitope on erythrocytes or H. mustelae lipopolysaccharide, and absorption with H. mustelae whole cells or red blood cells did not remove autoantibodies. In conclusion, ferrets naturally infected with H. mustelae generate antibodies that react with parietal cells, but these autoantibodies are not due to molecular mimicry.

Adherence of isogenic flagellum-negative mutants of Helicobacter pylori and Helicobacter mustelae to human and ferret gastric epithelial cells.

Isogenic flagellum-negative mutants of Helicobacter pylori and Helicobacter mustelae were screened for their ability to adhere to primary human and ferret gastric epithelial cells, respectively. We also evaluated the adherence of an H. pylori strain with a mutation in the flbA gene, a homologue of the flbF/lcrD family of genes known to be involved in the regulation of H. pylori flagellar biosynthesis. H. pylori and H. mustelae mutants deficient in production of FlaA or FlaB and mutants deficient in the production of both FlaA and FlaB showed no reduction in adherence to primary human or ferret gastric epithelial cells compared with the wild-type parental strains. However, adherence of the H. pylori flbA mutant to human gastric cells was significantly reduced compared to the adherence of the wild-type strain. These results show that flagella do not play a direct role in promoting adherence of H. pylori or H. mustelae to gastric epithelial cells. However, genes involved in the regulation of H. pylori flagellar biosynthesis may also regulate the production of an adhesin.

Molecular mimicry of ferret gastric epithelial blood group antigen A by Helicobacter mustelae.

BACKGROUND & AIMS: Molecular mimicry of Lewis blood group antigens by Helicobacter pylori may be involved in immune evasion by the bacteria and in the pathogenesis of chronic atrophic gastritis. Helicobacter mustelae infects ferrets naturally, causing gastritis, and may be involved in ulcerogenesis. The aim of this study was to determine if H. mustelae shows a similar form of molecular mimicry. METHODS: Antibodies raised against H. mustelae were used to stain ferret gastric tissue by immunoblotting, immunohistochemistry, and flow cytometry. Epitopes recognized by cross-reactivity were characterized by proteinase K and sodium metaperiodate treatment. RESULTS: H. mustelae antiserum reacted with H. mustelae and with ferret gastric tissue. Absorption of the antiserum with H. mustelae or ferret and rabbit gastric tissue removed the cross-reactive antibodies. Antibodies reacted with a blood group antigen A-like structure on ferret gastric epithelial cells and H. mustelae lipopolysaccharide. CONCLUSIONS: H. mustelae expresses a blood group-like antigen as part of its lipopolysaccharide that may be used as a method of immune evasion by mimicry of gastric epithelial cells. The cross-reactivity shown by H. mustelae-specific antibodies with gastric mucosa may suggest a role for autoantibodies in the pathogenesis of H. mustelae-induced gastritis in ferrets.

Effect of Helicobacter pylori eradication on the natural history of duodenal ulcer disease.

BACKGROUND: Duodenal ulcer disease is strongly associated with Helicobacter pylori infection of the gastric mucosa. Eradication of H pylori from the gastric mucosa in adults is associated with long term healing of ulcers. AIMS: To follow a cohort of children with duodenal ulcer disease for a minimum of two years after the eradication of H pylori. PATIENTS AND METHODS: Over a three year period, all children diagnosed with duodenal ulcer disease had their symptoms documented and their H pylori status evaluated. The histories of these children were carefully screened to determine previous symptoms and to document previous treatment regimens. RESULTS: Sixteen children were diagnosed with ulcers and 15 were available for treatment and long term follow up. The median age at which symptoms first occurred was 10.5 years (range, 6-14) and the median duration of symptoms was 24 months (range, 2-60). Ten of the children had been treated with H2 receptor antagonists for a median of 3.5 months (range, 1-60). Duodenal ulcers healed in all children after eradication of H pylori and all children have remained asymptomatic for a median of 37 months (range, 26-62). No child has required subsequent admission to hospital. CONCLUSION: Eradication of H pylori is very effective in the long term healing of duodenal ulcer disease. H pylori eradication should be the standard treatment for all infected children who present with duodenal ulcer disease.

Absence of effect of Lewis A and Lewis B expression on adherence of Helicobacter pylori to human gastric cells.

BACKGROUND & AIMS: Lewis b blood group antigen and antibodies to Lewis b inhibit the binding of stationary-phase Helicobacter pylori organisms to fixed sections of gastric tissue. The aim of this study was to determine the effect of expression of Lewis a and Lewis b on binding of H. pylori to primary gastric cells. METHODS: ABO and Lewis blood types were determined for 13 individuals. Cells were isolated from gastric biopsy specimens by collagenase digestion. Lewis antigen expression and adherence of H. pylori to the cells were quantitated using flow cytometry. RESULTS: Two of the three nonsecretors were found to express Lewis b on their cells. Nineteen of 19 individuals expressed Lewis a on their cells and 18 of 19 expressed Lewis b. The percentage of cells expressing Lewis antigens varied from individual to individual. H. pylori binding was independent of expression of Lewis antigens. Preincubation of cells with antibodies to Lewis antigens did not inhibit the adherence. CONCLUSIONS: H. pylori adheres to isolated human gastric cells in a manner that is not dependent on Lewis antigen expression on these cells, and expression of Lewis antigens on the surface of gastric cells is not dependent on Lewis antigen expression on erythrocytes.

In vitro evaluation of the role of antibodies against Helicobacter pylori in inhibiting adherence of the organism to gastric cells.

BACKGROUND: Once Helicobacter pylori infection is established, it is difficult to eradicate despite a persistent systemic and local immune response. It is not known whether immunisation can be used to prevent H pylori infection in humans. AIMS: To evaluate the effect of the human immune response on adherence of H pylori to gastric cells. METHODS: Human milk from a woman infected with H pylori and milk from a non-infected woman were each fractionated by chromatography on DEAE cellulose. Bacteria were incubated with either serum, human milk, human milk fractions, or secretory IgA before incubation with Kato III cells (cells from a gastric adenocarcinoma cell line). Bacterial adherence to the cells was assessed using flow cytometry. RESULTS: Serum from both the H pylori infected and non-infected women killed H pylori. This resulted from the action of complement as heating the serum to 56 degrees C for 30 minutes abolished the bactericidal activity. Immunoglobulin fractions from serum of both infected and non-infected women did not inhibit H pylori adherence to Kato III cells. Human milk from the woman infected with H pylori and from the non-infected woman inhibited binding of H pylori to Kato III cells by 50 to 70%. Secretory IgA isolated from human milk had minimal inhibitory effect on adherence and this was notably less than the inhibitory effect of whole human milk. CONCLUSIONS: Human milk inhibits adherence of H pylori to Kato III cells and this inhibition is independent of whether or not the donor is infected with H pylori. Secretory IgA has minimal inhibitory effect on H pylori adherence.

Adherence of Helicobacter pylori to the gastric mucosa.

Bacterial adhesion to the intestinal epithelium is a critical initial step in the pathogenesis of many enteric diseases. Helicobacter pylori is a duodenal pathogen that adheres to the gastric epithelium and causes gastritis and peptic ulceration. The mechanism by which H pylori causes disease has not been elucidated but adherence to the gastric mucosa is thought to be an important virulence determinant of the organism. What is known about adherence of H pylori to the gastric mucosa is summarized. Topics discussed are the mechanism of H pylori adherence; in vitro and in vivo models of H pylori infection; and adherence and potential adhesins and receptors for H pylori.

Consumer-focused preadmission testing: a paradigm shift.

The current trend in the health care environment is to redesign the delivery of services to make them customer friendly as opposed to hospital convenient. The paradigm shift meets and exceeds customers, expectations by bringing the points of service to the patient. Preadmission testing is accomplished by specially educated, registered professional nurses, who complete the nursing assessment, laboratory work, electrocardiograms, social and rehabilitative services referrals, and patient teaching in a primary care framework. This redesign results in a cost savings for the institution, increased patient and physician satisfaction, and decreased idle time for patients and staff.

Language maintenance and language shift: community languages in Australia, 1996.

"There is a continuing significant shift to English spoken in the home among Australia's established community language groups. There are also success stories in language maintenance. Factors influencing language use include the distribution of speakers, the age profile of the community, intermarriage patterns and cultural distance from Anglo-Australians. Australia-wide, the shift rates to English spoken at home range between three percent from Macedonian and 62 percent from Dutch in the first generation, and 15 percent from Macedonian and 95 percent from Dutch in the second generation."

Linguistic diversity in Australia.

"This paper explores the changing patterns of language diversity in Australia, Sydney and Melbourne between 1991 and 1996. It shows that there has been a great increasing linguistic diversity, accompanied by an overall decline in the use of ¿older' community languages in favour of ¿newer' languages from Asia and the Middle East."

Cell envelope characteristics of Helicobacter pylori: their role in adherence to mucosal surfaces and virulence.

Helicobacter pylori colonises the gastric mucosa of humans and causes both antral gastritis and duodenal ulcer disease. Exactly how H. pylori causes disease is not known but several pathogenic determinants have been proposed for the organism. These include adhesins, cytotoxins and a range of different enzymes including urease, catalase and superoxide dismutase. Surface molecules of H. pylori such as flagella, lipopolysaccharide, the urease enzyme and outer membrane proteins are putative adhesin molecules. While phosphatidylethanolamine and the Lewis(b) blood group antigen have been proposed as receptor molecules for the organism the exact mechanism by which H. pylori adheres to the gastric mucosa has still to be identified. Characterisation of the adhesins of H. pylori could lead to the development of adhesin analogues for use in the inhibition of colonisation and improved therapy for ulcer disease. In vivo studies with isogenic mutants which are incapable of adhering to the gastric mucosa would greatly clarify the significance of adherence. Such mutants could possibly be useful as a vaccine against infection with wild-type organisms.

The urease enzyme of Helicobacter pylori does not function as an adhesin.

Helicobacter pylori urease is essential for colonization of the gastric mucosa irrespective of whether the stomach is acidic or hypochlorhydric. It has therefore been speculated that the enzyme functions as an adhesin. The aim of this study was to compare the adherence of H. pylori N6 with the adherence of an isogenic urease-negative mutant, strain N6(ureB::TnKm), to gastric cells. Strain N6 originated from a patient with gastritis. Strain N6(ureB::TnKm) is specifically modified in the gene which encodes the large subunit of urease, UreB, and hence does not form a UreA-UreB enzyme complex. We have used flow cytometry to assess the adherence of H. pylori to the cells. We have also used phase-contrast microscopy to assess the adherence of the organism to Kato III cells. In the absence of urea both strains bound to Kato III cells and to primary gastric cells. Binding of both strains to the cells occurred rapidly. The presence of urea in the incubation medium decreased the binding of strain N6 to the cells. This was due to a rise in the pH of the incubation medium, which caused loss of viability of the organism. Urea had no effect on the adherence of strain N6(ureB::TnKm). We conclude that the urease of H. pylori does not play a role in the adherence of the organism to gastric cells.

Helicobacter pylori requires an acidic environment to survive in the presence of urea.

The aim of this work was to study the significance of the urease enzyme in promoting Helicobacter pylori survival in various environments. A urease-positive H. pylori isolate, strain N6, and an isogenic urease-negative strain, strain N6(ureB::TnKm), were incubated in phosphate-buffered saline at a pH ranging from 2.2 to 7.2 for 60 min at 37 degrees C in both the presence and the absence of 10 mM urea. The number of CFU per milliliter in each solution, the pH of the bacterial supernatant, and the amounts of ammonia present in the solutions were measured. H. pylori N6 survived well in solutions with pH values ranging from 4.5 to 7.0 in the absence of urea but survived in solutions only with an initial pH below 3.5 in the presence of urea. Neither strain grew after incubation in an alkaline environment. The pH of an acidic solution (i.e., 3.5) rose rapidly to 8.45 in the presence of the wild-type strain and urea. The urease-negative mutant survived in solutions with pH values ranging from 4.5 to 7.2 irrespective of the presence of urea. Ammonia was present in significant amounts when H. pylori N6 was incubated in the presence of urea. Strain N6 survived exposure to concentrations of ammonia as high as 80 mM. The acid environment of the stomach may be crucial for H. pylori survival in the presence of urea. H. pylori does not survive in the normal environment in the presence of urea because of the subsequent rise in pH rather than ammonia toxicity.