H. pylori has been classified by World Health Organization as type I carcinogen for its association with gastric cancer. Among its suggested pathological pathways is oxidative stress, which may reduce the bioavailability of dietary antioxidants. The main objectives of this thesis were to estimate the prevalence of H. pylori infection in Ontario and to assess its effect on the bioavailability of two main dietary antioxidants, vitamins E and C. To estimate the prevalence of H. pylori infection, a volume of 10 ul of plasma was aliquoted from stored blood of 1306 adults from Ontario. The blood samples belonged to controls of a population-based study of colorectal cancer. The overall weighted seroprevalence of H. pylori was 23.1% (95% CI: 17.7-29.5) with males having higher infection rates than females. Seroprevalence of the infection increased with age and number of siblings. Being non-white, born outside Canada and immigrating at an age greater than 20 years increased risk for H. pylori infection. An inverse association with seroprevalence was found for education and alcohol consumption. In order to investigate whether H. pylori positive compared to H. pylori negative subjects have lower changes in plasma concentrations of ascorbic acid and alpha tocopherol when supplemented with these vitamins, H. pylori negative (n=32) and H. pylori positive (n=27) volunteers received vitamin C (500 mg) and alpha tocopherol (400 IU) supplementation daily for 28 days. H. pylori infection status was determined by 13C urea breath test. Post supplementation plasma ascorbic acid and alpha tocopherol were significantly higher than pre supplementation concentrations in both groups. The changes in plasma ascorbic acid and alpha tocopherol were not significantly different between H. pylori negative and positive groups (ascorbic acid: 13.97±16.86 vs. 20.87±27.66, p=0.76; alpha tocopherol: 15.52±9.4 vs. 14.47±15.77; p=0.39 for H. pylori negative and positive groups respectively). The weighted seroprevalence of H. pylori infection was 23.1%. Age, sex, ethnicity, place of birth, age at immigration, education and alcohol consumption were factors associated with the infection prevalence in the population studied. In addition, we found no effect of H. pylori infection on the bioavailability of vitamins E and C.

H. pylori has been classified by World Health Organization as type I carcinogen for its association with gastric cancer. Among its suggested pathological pathways is oxidative stress, which may reduce the bioavailability of dietary antioxidants. The main objectives of this thesis were to estimate the prevalence of H. pylori infection in Ontario and to assess its effect on the bioavailability of two main dietary antioxidants, vitamins E and C. To estimate the prevalence of H. pylori infection, a volume of 10 ul of plasma was aliquoted from stored blood of 1306 adults from Ontario. The blood samples belonged to controls of a population-based study of colorectal cancer. The overall weighted seroprevalence of H. pylori was 23.1% (95% CI: 17.7-29.5) with males having higher infection rates than females. Seroprevalence of the infection increased with age and number of siblings. Being non-white, born outside Canada and immigrating at an age greater than 20 years increased risk for H. pylori infection. An inverse association with seroprevalence was found for education and alcohol consumption. In order to investigate whether H. pylori positive compared to H. pylori negative subjects have lower changes in plasma concentrations of ascorbic acid and alpha tocopherol when supplemented with these vitamins, H. pylori negative (n=32) and H. pylori positive (n=27) volunteers received vitamin C (500 mg) and alpha tocopherol (400 IU) supplementation daily for 28 days. H. pylori infection status was determined by 13C urea breath test. Post supplementation plasma ascorbic acid and alpha tocopherol were significantly higher than pre supplementation concentrations in both groups. The changes in plasma ascorbic acid and alpha tocopherol were not significantly different between H. pylori negative and positive groups (ascorbic acid: 13.97±16.86 vs. 20.87±27.66, p=0.76; alpha tocopherol: 15.52±9.4 vs. 14.47±15.77; p=0.39 for H. pylori negative and positive groups respectively). The weighted seroprevalence of H. pylori infection was 23.1%. Age, sex, ethnicity, place of birth, age at immigration, education and alcohol consumption were factors associated with the infection prevalence in the population studied. In addition, we found no effect of H. pylori infection on the bioavailability of vitamins E and C.

Four small ubiquitin-like modifier (SUMO) isoforms termed SUMO-1, -2, -3 and -4 have been identified in human. Most SUMO-1/2 proteins are localized in nucleus, whereas SUMO-1 protein exhibits 44% homolog with SUMO-2 protein. Over 50 proteins have been identified as the target proteins for SUMO-1 modification and these include transcription factors, their cofactors, regulators, nuclear body proteins, nuclear pore complex proteins, DNA repair proteins, and viral proteins. However, only a handful of SUMO-2 targets are known and SUMO-2 modification may response to environmental stress. SUMO-1 may interact with Fas/APO-1 and TNF receptor 1 on yeast two hybrid interactions; however, it is not clear whether SUMO would enhance apoptosis or response to biological stress. Helicobacter pylori (H. pylori) defined as a gastric carcinogen is definite a biological stress to the cells. It causes gastric epithelial cell damage by apoptosis. In this study whether the SUMO-1/2 pathway constitutes an element of the cellular response to the H. pylori infection was examined. Overexpression of SUMO-1/2 for 12 hours had no effects on the apoptotic activities of cells; however it enhanced apoptosis during H. pylori infection. Overexpression of SUMO-1/2 for 48 hours increased the apoptosis of cells; however only SUMO-2 enhanced apoptosis significantly during H. pylori infection. The enhancements are more powerful for SUMO-2 than that of SUMO-1. Inactive SUMO, a cytoplasm dispersed sumoylation-incompetent mutant, eliminates such activities, suggesting that sumoylation or SUMO interactions are involved in the apoptotic enhancement. The percentages of cells with cytoplasmic SUMO-2 were increased 22% by H. pylori infection for 2 hours and SUMO-1 were increased 11%. The translocalization of SUMO-1 was blocked by leptomycin B; however, it did not work on SUMO-2. Leptomycin B could also inhibit SUMO-1 enhanced apoptosis during H. pylori infection, whereas it had no effects on SUMO-2. It is concluded that SUMO-1/2 pathway constitutes an element of the cellular response to H. pylori infection by enhancing apoptosis through shuttling from nucleus to cytoplasm. SUMO-1 is via a CRM1-dependent pathway while SUMO-2 is via a CRM1-independent pathway.

Helicobacter pylori (H. pylori) causes peptic ulcer or gastric cancer through different virulence factors including lipopolysaccharides (LPS), the cytotoxin-associated gene A product (CagA), and vacuolating cytotoxin A (VacA) etc. It stimulated mitogen-activated protein (MAP) kinase signaling cascades. Small ubiquitin-related modifier (SUMO) is a member of ubiquitin-related protein modifiers. However, the mechanisms of the involvement of SUMO-1 on H. pylori induced apoptosis were not clear. Our previous study showed that the expression of RFP-SUMO-1 and apoptosis were increased significantly by fluorescence microscopy assays on RFP-SUMO-1 transfectants during H. pylori infection. In addition, the cytoplasmic SUMO-1 was increased during infection and positively associated with apoptosis. Here, how SUMO-1 was involved in the apoptotic signaling enhancement during H. pylori infection was studied. Results showed that H. pylori infection enhanced MAP kinase activation and the effects were stronger on the SUMO-1 overexpressed cells. However, it was not affected by the secretion of CagA or VacA toxins of H. pylori. To investigate the possible role of SUMO-1 on MAPKs mediated signaling pathways, three selective MAPKs inhibitors were used on RFP-SUMO-1 overexpressed cells. Only p38 inhibitor decreased the levels of apoptosis during H. pylori infection and the expression of p53 was increased on RFP-SUMO-1 1 overexpressed cells. Thus, p38 and p53 pathways were suggested to be involved in SUMO-1 enhanced apoptosis during H. pylori infection. In addition, the nuclear localization of NF-£eB and expression of COX-2 were enhanced on RFP-SUMO-1 overexpressed cells. Moreover, more nuclear NF-£eB and cytoplasmic as well as nuclear RFP-SUMO-1 were observed during H. pylori infection. Our data suggest that H. pylori infection enhances SUMO-1 expression which activates MAPKs on both the pro-apoptotic p38-p53 pathway and the anti-apoptotic ERK-NF-£eB-COX2 pathway. The detail mechanisms on how cells making the final decision on the survival or apoptosis were still not clear and deserving to investigate.

Helicobacter pylori (H. pylori) infection causes achlorydria, depressed gastric acid barrier, impaired immune response and is suspected in bacterial overgrowth and diarrhoea. These features of the infection are known to cause significant malabsorption of nutrients and impairment of linear growth in children. The prevalence of H. pylori infection in children is known to be much higher in developing countries, especially among the lower socio-economic groups. The true prevalence of infection in urban children in Mexico and its impact on their growth are largely unknown. This study examined the prevalence of H. pylori infection in school children from an urban area in Northwest Mexico and attempted to identify the risk factors that predispose individuals to infection in childhood; as well as to relate the presence of this infection to growth of children. The cross-sectional study was conducted in 1997/98 in the poorest socio-economic sectors of the city of Hermosillo, Sonora, among 178 children aged 9 and 10 years. H. pylori status was determined in children by the 13C-urea breath test. Anthropometric (weight and height) and haemoglobin measurements along with analysis of faecal samples and a 24-hour dietary recall were carried out in each child. Family sociodemographic/socio-economic status and living conditions data were elicited from parents by interview via structured questionnaires. The overall prevalence rate of H. pylori infection for the children in Hermosillo as determined by this study was 47.1%. The findings indicate that rural-born father, number of siblings, the type of main water supply (one tap in the yard) and the sharing of bed by the study child are important risk factors for acquiring the H. pylori infection. A borderline significant but small effect of H. pylori infection on height for-age was observed in this study. H. pylori infection was found to be positively highly associated with Hymenolepis nana. No differences in mean energy, protein and iron intakes between H. pylori positive and negative children were observed. However, significant differences in the mean energy, protein and iron intakes were observed between boys and girls. H. pylori infection and enteric parasites were not significantly correlated with the presence of anaemia.

Made available in DSpace on 2014-06-12T23:04:25Z (GMT). No. of bitstreams: 2 arquivo8874_1.pdf: 1552701 bytes, checksum: ca1f64cd2a9ab7f1dd8b3732c2cc688d (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2007 / O bacilo Helicobacter pylori é atualmente considerado como o agente etiológico mais importante das gastrites em seres humanos e como um fator de risco para o surgimento das doenças ulcerativas do carcinoma gástrico. Estima-se que 50% da população mundial está infectada por esta bactéria. Atualmente, apenas estudos subjetivos e qualitativos têm sido realizados na análise da colonização do H. pylori. O objetivo deste estudo foi avaliar quantitativamente, através de análise morfométrica, a colonização pelo H. pylori em biópsia de pacientes com diferentes lesões gástricas (gastrites e úlcera). Para o estudo utilizou-se biópsias gástricas de 239 pacientes (95 homens e 144 mulheres) com idade média de 45 anos, provenientes de diferentes municípios do estado de Pernambuco. Os cortes histológicos (4μm) foram corados pelo Giemsa e analisado através de microscopia óptica. O estudo morfométrico foi realizado por meio de um sistema digital de análise de imagens onde as áreas de interesse obtidas foram processadas utilizando-se o software OPTIMAS®. Os resultados indicam uma incidência de 39% de lesões inflamatórias gástricas associadas à infecção por Hp com maior ocorrência (60,3%) no gênero feminino e com faixa etária entre 31-45 anos. Quanto às lesões gástricas mais freqüentes observou-se que a gastrite crônica ativa foi a mais evidente em cerca de 90,2% dos casos estudados. Houve uma correlação positiva entre a análise qualitativa (semi-quantitativa) e a análise morfométrica (número médio de bacilos Hp, por área), principalmente quando se comparou os parâmetros numerosos bacilos com os moderados e raros . A partir destes dados pode-se concluir que os estudos referentes aos aspectos da infecção da mucosa gástrica pelo Hp, e mais especificamente os níveis de infecção quanto ao número de bacilos e extensão das áreas afetadas são de sua importância para que se possa conhecer melhor a evolução das lesões gástricas resultantes deste quadro infeccioso e em que situações e grupos humanos podem representar fatores de risco para o desenvolvimento de lesões mais graves como o câncer

RESUME DE LA THESE Le rôle majeur de l’Helicobacter pylori dans l’étiopathogénie des maladies gastroduodénales (gastrite, ulcère gastrique et duodénal, lymphome gastrique) est bien établi aujourd’hui. L’OMS l’a reconnue comme jouant un rôle important dans la survenue des lésions cancéreuses gastriques. La prévalence de l’infection à H. pylori varie selon les pays de 20% à 90% avec des taux supérieurs à 60% dans les pays en développement, dont le Bénin. Les méthodes usuelles de diagnostic sont soit invasives nécessitant une endoscopie gastrique avec biopsies (test rapide à l’urée, histologie, culture et PCR), soit non-invasives (test respiratoire à l’urée marquée au carbone, sérologie, et détection de l’antigène dans les selles). La trithérapie associant un inhibiteur de la pompe à protons (IPP) et deux antibiotiques choisis parmi l’amoxicilline, la clarithromycine et le métronidazole est recommandée pour son traitement. La survenue de résistance des souches H. pylori aux différents antibiotiques devient une cause majeure de l’échec des régimes d’éradication. Afin d’évaluer l’applicabilité et l’efficacité des régimes thérapeutiques recommandés en pratique courante, et à partir d’une étude de cohorte prospective, nous avons étudié la prévalence de l’infection à H. pylori chez les patients consultant à la clinique de Gastroentérologie de l’hôpital universitaire Erasme à Bruxelles, déterminé son taux de résistance primaire aux antibiotiques, et évalué le taux d’éradication d’H. pylori par la trithérapie. Nous avons aussi évalué la performance du test de détection de l’antigène d’H. pylori dans les selles pour le diagnostic chez l’adulte (avant traitement) comparé avec les méthodes de référence (culture, histologie), également dans le contrôle de l’éradication. Au Bénin, nous avons évalué à partir d’une étude transversale prospective, la prévalence de l’infection à H. pylori dans une population en milieu urbain et rural. Nous avons déterminé la distribution par famille des sujets infectés, ainsi que l’influence des variables démographiques individuelles, et les caractéristiques socio-économiques familiales sur le risque de l’infection. La prévalence de résistance primaire à la clarithromycine et au métronidazole fut observée respectivement dans 3% et 31% des souches isolées. Aucune résistance primaire à l’amoxicilline et à la tétracycline n’a été observée. Les analyses en intention de traiter, ont montré que H. pylori a été éradiqué chez 80% des patients inclus dans l’étude thérapeutique. Le taux d’échec d’éradication fut de 20%. Comparé au 14C-TRU, le test HpSA avait une sensibilité de 100%, une spécificité de 91%, VPP de 69%, VPN de 100%. De même, la sensibilité du test HpSA par rapport aux deux méthodes usuelles (culture et histologie) est de 96.5% pour une spécificité de 91.2%, une VPP de 90.3% et une VPN de 96.8%. Au Bénin, la prévalence de H. pylori était de 75.4% en ville et de 72.3% dans le village (p = 0.459). Aucune association n’a été observée avec l’âge, le sexe, le niveau d’instruction, la taille du ménage, l’activité économique ou le mode d’approvisionnement en eau potable. Le taux d’infection était plus élevé chez les enfants dont les parents étaient infectés et chez ceux ayant une mère H. pylori positive (p < 0.001). L’analyse multivariée par régression logistique a montré que la densité d’occupation des dortoirs [OR (95%) = 9.82 (4.13-23.31)] p < 0.001), et le statut des mères dans le ménage ([OR (95%) = 3.85 (1.53-9.67)] p < 0.001) étaient les prédicteurs indépendants de l’infection par H. pylori. Le risque de l’infection chez les enfants était 13 fois plus élevé quand les deux parents sont simultanément positifs OR (95% CI) = 13.6 (3.63-51.22), il l’était respectivement de 5.3 (1.52-18.45); 2.7 (0.47-15.44), quand la mère et le père sont positifs p < 0.001. Aussi le risque d’infection à H. pylori comparé aux enfants qui dorment seul dans leur chambre, était élevé pour ceux qui dorment avec un ou deux personnes OR (95% CI) = 5.2 (1.08-25.16), p < 0.05, et plus élevé chez les enfants qui dorment à 4 ou plus OR (95% CI) = 16.6 (2.66-103.44), p < 0.005, comparé à ceux qui dorme seuls. Donc, le contact avec des personnes infectées au sein de la famille et la vie en promiscuité, étaient associés avec un risque d’infection plus élevé indiquant une transmission intrafamiliale de l’infection par H. pylori. En conclusion, nos résultats montrent une séroprévalence encore élevée de l’infection à H. pylori dans la population béninoise. Une surveillance de l’épidémiologie accompagnée de mesures de prévention ciblées sur les facteurs potentiels de risque de l’infection doit être poursuivie. La validation du test de détection de l’antigène dans les selles avant traitement et dans le contrôle de l’éradication de la bactérie pour le suivi thérapeutique des patients infectés, est une alternative intéressante notamment au Bénin. Le taux de résistance primaire pour le métronidazole est actuellement stable en Belgique, alors que la prévalence de la résistance à la clarithromycine mérite d’être précisée par d’autres études multicentriques. La trithérapie classique à base d’inhibiteur de la pompe à protons–amoxicilline-clarithromycine reste recommandable en première intention. La surveillance épidémiologique de l’infection basée sur la prévalence locale des souches clarithro-résistantes et métronidazole-résistantes devrait être poursuivie. SUMMARY OF THE THESIS The major role of H. pylori in the etiopathogeny of various gastroduodenal diseases (gastritis, gastric and duodenal ulcers, gastric lymphoma) is well established today. The World Health Organization concluded that H. pylori plays a causal role in the chain of events leading to cancer of the stomach. The prevalence of H. pylori infection varies by country from 20% to 90%, with higher prevalence rates over 60% observed in developing countries, including Bénin. The usual methods allowing the diagnosis of the gastric infection by H. pylori are either invasive, requiring a gastric endoscopy and biopsies (fast urease test, anatomopathological examination, culture and PCR), or noninvasive (breath test with 13C or 14C marked urea, serology and stool antigen detection). Triple therapy associating a proton pump inhibitor (PPI) with two antibiotics, chosen between amoxicillin, clarithromycin and metronidazole, is currently recommended. Resistance of H. pylori strains to antibiotics becomes a major determinant in the failure of eradication of regimens. To evaluate the applicability and efficacy of the therapeutic recommendations in our pratice, based on a prospective study, we studied the prevalence of H. pylori infection in the outpatient population of the Gastroenterology clinic at the Erasme University hospital in Brussels, determined its rate of primary resistance to antimicrobial agents and evaluated the rate of eradication of H. pylori by triple therapy. We also evaluated the performance of a stool antigen detection test for the diagnosis of H. pylori infection in adults (before treatment) compared with reference methods (culture and histology) as well as in control of eradication. In Benin, we evaluated by a cross-sectional study the prevalence of the infection with H. pylori in the population living in urban and rural environment. We determined the family distribution of infected subjects as well as the influence of individual demographic variables and of the socio-economic family characteristics on the risk of infection. In Brussels, primary resistance to clarithromycin and metronidazole was observed in 3% and 31% of the isolates, respectively. No primary resistance to amoxicillin and tetracycline was observed. By intention to treat analysis, H. pylori was eradicated in 80% of patients included in the therapeutic study. The rate of eradication failure was 20%. In comparison with 14C-Urea breath test, the H. pylori Stool Antigen test showed a sensitivity of 100%, a specificity of 91 %, PPV of 69%, and NPV of 100%. Compared to the reference methods (culture and histology), the HpSA test had a sensitivity of 96.5% and a specificity of 91.2%. PPV of 90.3% and NPV of 96.8%. In Benin, the prevalence of H. pylori antibodies was 75.4% in town and 72.3% in the village (P= 0.459). No association was found between infection and age, sex, education level, size of the household, economic activity or source of drinking water. The infection rate was higher in children of parents who were both infected and also in those whose mother was infected (p < 0.001). By logistic regression analysis, the density of occupation of dormitories (more than three persons sharing dormitory, [OR (95%) = 9.82 (4.13-23.31)] p < 0.001), and mother status within the household ( [OR (95%) = 3.85 (1.53-9.67) ] p < 0.001), were independent predictors for H. pylori infection. The risk of H. pylori infection in children was 13 times higher when the two parents were simultaneously positive: OR (95% CI) = 13.6 (3.63-51.22) and it was respectively of 5.3 (1.52-18.45); 2.7 (0.47-15.44), when mother and father were positive p < 0.001. H. pylori infection risk in children was higher for a sharing a dormitory with one or two persons, OR (95% CI) = 5.2 (1.08-25.16), p < 0.05 and was even higher if a dormitory of 4 persons or more, OR (95% CI) = 16.6 (2.66-103.44), p < 0.005 as compared to sleeping alone. Family contact with infected persons and crowded living conditions were associated with increased risk of infection consistent with intrafamilial H. pylori transmission. In conclusion, our results confirm a still high H. pylori seroprevalence in population in Benin. An epidemiolgic survey with prevention mesures targeted on potential risk predictors should be going on. Validation of antigen detection test in patients stools before treatment and for eradication control could be an interested alternative, notably in Benin. Primary resistance rate on metronidazole is stable today in Belgium, though the resistance prevalence on clarithromycin should be determined by other multicentric studies. Standard triple therapy by (PPI)-amoxicillin-clarithromycin is still recommended in first intention to treat. Epidemiological survey of infection based on local prevalence of claritromycin-resistant and metronidazole-resistant strains should be continued.

Throughout history a diversity of animal species have been used and studied extensively in the development of vaccines for the benefit of humans and animals alike. As mice are a relatively easy species to maintain, handle and manipulate, and have the advantage of being cost effective, they are commonly employed as animal models in the investigation of immunisation strategies against mucosal associated pathogens. Vaccine research against the human gastric pathogen Helicobacter pylori is extensively conducted in a mouse model and typically uses intra-gastric administration for the testing of potential vaccine candidates. An inherent complication with this route, however, is that the vaccine constituents may be inadequately delivered to sites of specific immunity and consequently may not be the optimal method for vaccine delivery. In the present study a mouse model of H. pylori infection was used to determine the efficacy of alternate mucosal routes of immunisation from examination of protective immunity, immune responses and the practical aspects of vaccine administration. Commencing with the optimisation of intra-intestinal immunisation, the direct injection of a H. pylori vaccine to initiator sites of the mucosal immune system established baseline data of dose rates for the comparative analysis of intra-gastric, intra-nasal and intra-rectal immunisation. Following the development of simple administration techniques whilst maintaining the welfare of the animals, intra-nasal immunisation was shown to elicit the highest level of prophylaxis against H. pylori challenge. Effective prophylaxis was also shown to be dependent upon a specific ratio of the vaccine constituents. When using whole cell lysate of H. pylori and the mucosal adjuvant cholera toxin, the ratio of antigen:adjuvant for optimal protective immunity was 10:1. The outcomes of this study have proved conclusively the necessity for optimisation of all aspects of immunisation in an animal model of infection. / Master of Science (Hons)

We have previously reported a high prevalence of H. pylori DNA in saliva. In this study, the cytotoxin genotypes of H. pylori strains from both stomach and saliva were compared in 31 patients with gastritis and peptic ulcer. The cagA, vacA m1, vacA m2, and vacA s1 genotypes were analyzed by PCR. The 417 bp PCR products from three patients were also subjected to DNA sequencing analysis. There was 95% agreement between stomach H. pylori isolates and their corresponding saliva DNA in at least one cytotoxin genotype; 86% agreement with two cytotoxin genotypes; 59% agreement with three cytotoxin genotypes; and 27% agreement with all four cytotoxin genotypes studied. DNA sequencing from three patients showed 78.0%, 64.0%, and 66.9% homology of H. pylori from both sources, respectively. The data suggest that more than one H. pylori strain may exist in the stomach and saliva in the same patient.

No description available.