Faculty Bibliography

AIM: To evaluate the effectiveness of triple therapy containing either omeprazole or ranitidine bismuth citrate (RBC) to treat H. pylori infection in Vietnamese duodenal ulcer patients. METHODS: Patients infected with H. pylori were randomized to receive either omeprazole (20 mg b.d.), clarithromycin (500 mg b.d.) and amoxycillin (1 g b.d.) for 10 days (OAC), or RBC (400 mg b.d.), clarithromycin (500 mg b.d.) and amoxycillin (1 g b.d.) for 10 days (RAC). H. pylori eradication and ulcer healing was established by a follow-up oesophagogastroduodenoscopy (EGD) at least 4 weeks after therapy. Side-effects and compliance were assessed. RESULTS: One hundred and four out of 108 (96%) patients with a duodenal ulcer were infected with H. pylori. Eighty per cent of infected patients had detectable CagA IgG antibodies. Fifty-seven patients received OAC and 47 received RAC. OAC eradicated H. pylori in 91 and 86% of patients by per protocol (PP) and intention-to-treat (ITT) analysis, respectively. PP and ITT eradication rates for RAC were 96 and 91%. Ulcer healing at the follow-up EGD was 89% with OAC and 100% with RAC. Side-effects were minor. No patient failed to complete the protocol due to side-effects. CONCLUSION: Triple therapy with either omeprazole or RBC is highly effective in eradicating H. pylori and healing duodenal ulcer in Vietnamese patients

Entamoeba histolytica genome was analysed by pulsed field gel electrophoresis under conditions to separate linear chromosomes in the 170-1400 kb range. We identified linear DNA molecules of 227, 366, 631, 850, 1112 and 1361 kb (mean sizes obtained by three different methods) and we estimated their reorientation times and migration velocities at various experimental conditions. DNA shift mobility assays, using ethidium bromide, suggested that bands migrating at 227 and 631 kb contain linear and circular DNA, whereas a band at 436 kb has only circular DNA. We obtained a regression equation relating sizes of supercoiled DNA molecules with their migration velocities during a pulse at constant electric field and temperature. We also developed a computer program (EHPATTERNS) that predicts the migration per pulse and the resolution order of circular and linear E. histolytica DNA at different pulse times and constant driving and frictional forces. The simulation showed that linear DNA molecules frequently co-migrate with circular molecules, but circular molecules change when the pulse time varies. This molecular mixture generates broad bands and difficulties in the interpretation of the molecular karyotype of E. histolytica

Helicobacter pylori infection in humans is associated with diverse of clinical outcomes which are partly attributed to bacterial strain differences. Secreted bacterial products are thought to be involved in the pathogenesis caused by this non-invasive bacterium. Electron microscopy of gastric biopsies from infected individuals revealed blebbing of the H. pylori outer membrane, similar to the process of outer membrane vesicle shedding which occurs when the bacterium is grown in broth. Porins, a class of proinflammatory proteins, were observed in the outer membrane vesicles. The VacA cytotoxin, which is produced by 50-60% of H. pylori strains and associated with increased pathogenesis of infection, was also found to be vesicle-associated and biologically active. This supports the hypothesis that these vesicles represent a vehicle for the delivery of damaging bacterial products to the gastric mucosa

Across populations of children, Helicobacter pylori prevalence ranges from under 10% to over 80%. Low prevalence occurs in the U.S., Canada, and northern and western Europe; high prevalence occurs in India, Africa, Latin America, and eastern Europe. Risk factors include socioeconomic status, household crowding, ethnicity, migration from high prevalence regions, and infection status of family members. H. pylori infection is not associated with specific symptoms in children; however, it is consistently associated with antral gastritis, although its clinical significance is unclear. Duodenal ulcers associated with H. pylori are seldom seen in children under 10 years of age. H. pylori-infected children demonstrate a chronic, macrophagic, and monocytic inflammatory cell infiltrate and a lack of neutrophils, as compared with the response observed in adults. The effect of H. pylori infection on acid secretion in children remains poorly defined. The events that occur during H. pylori colonization in children should be studied more thoroughly and should include urease activity, motility, chemotaxis, adherence, and downregulation of the host response. The importance of virulence determinants described as relevant for disease during H. pylori infection has not been extensively studied in children. Highly sensitive and specific methods for the detection of H. pylori in children are needed, especially in younger pediatric populations in which colonization is in its early phases. Criteria for the use of eradication treatment in H. pylori-infected children need to be established. Multicenter pediatric studies should focus on the identification of risk factors, which can be used as prognostic indicators for the development of gastroduodenal disease later in life

BACKGROUND: Acquisition of Helicobacter pylori infection occurs mainly during childhood. To study the events associated with H. pylori colonization in children it is important to have reliable diagnostic methods. Our objective was to validate invasive and noninvasive tests for diagnosis of H. pylori infection in children before and after antimicrobial treatment. METHODS: Before treatment, invasive rapid urease test (RUT) culture and histology, as well as the noninvasive carbon-13 urea breath test (13C-UBT) and serology were validated in 59 children. The gold standard for H. pylori infection was any of three positives of the five tests. After antimicrobial treatment culture, histology, and 13C-UBT were validated in 43 children to determine eradication. The gold standard for eradication was negative in all three tests. RESULTS: For primary diagnosis, RUT was the most sensitive and specific test, followed by 13C-UBT, which performed better than serology, culture, and histology. Concordance tests also showed that RUT and 13C-UBT performed better. For determination of eradication, 13C-UBT and histology were better than culture, which showed poor sensitivity. CONCLUSIONS: RUT performed better for primary diagnosis. However, as endoscopy might not be indicated in most children, 13C-UBT could be the test of choice for diagnosis of H. pylori infection both before and after eradication treatment