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No. of bitstreams: 2 license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) Dissertacao_CaracteristicasEpidemiologicasRelativas.pdf: 753877 bytes, checksum: 9bc3af6fdd01ee36ff7a2050b8fc7b2b (MD5) Previous issue date: 2009 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A infecção pela Helicobacter pylori é uma das mais comuns em humanos e apesar de possuir tropismo pelo estômago, pode ser encontrada na cavidade oral, mantendo uma relação comensal com o hospedeiro, enquanto a cárie dental também é uma doença infecciosa e resulta do metabolismo da placa bacteriana. Ambas as infecções apresentam alta prevalência em países em desenvolvimento, pois estas populações estão mais expostas a fatores ambientais de risco, e normalmente são adquiridas durante a infância. A prevalência destas infecções foi investigada na cavidade oral de escolares assintomáticos para doenças gástricas, provenientes de uma população de Belém-Pa, relacionando-se a alguns parâmetros de higiene e saúde bucal, condição socioeconômica e fatores de susceptibilidade genética como os grupos sanguíneos ABO e Lewis. Foram investigados 104 indivíduos, com idade média de 17 anos. De todos os participantes foram coletadas amostras de saliva e placa dental. A saliva foi coletada para identificação do estado secretor ABO e Lewis e estimação dos parâmetros salivares, e ambas, saliva e placa dental, foram coletadas para analise molecular dos genes 16S RNAr da H. pylori e FUT2. A H. pylori foi detectada em 79,8% dos escolares, com freqüência de 66,35% na placa dental e 58,65% na saliva. A prevalência de cárie foi de 82,8% na população estudada. A avaliação clínica da saúde bucal mostrou que o CPO-D médio encontrado foi de 3,53. Observou-se que a experiência de cárie tende a aumentar à medida que acresce a idade e que a infecção por H. pylori foi maior na primeira infância. O grau de instrução e o número de visitas ao dentista mostraram diferenças significantes em relação a presença de H. pylori. A distribuição fenotípica dos grupos sanguíneos ABO e Lewis não mostrou diferenças significantes entre indivíduos infectados e não-infectados, que expliquem haver maior susceptibilidade genética para infecção por H. pylori e cárie dental. No conjunto desta analise as elevadas freqüências encontradas denotam a necessidade de cuidados e tratamento das doenças dentais, como a cárie e sugere-se que a H. pylori na cavidade oral pode contribuir para a infecção e re-infecção do estômago após tratamento. / The infection by Helicobacter pylori is one of the most common in humans and despite having tropism by stomach, can be found in the oral cavity, maintaining a commensal relationship with the host, while dental caries is also an infectious disease and results from the metabolism of the bacterial plaque. Both infections are highly prevalent in developing countries, since these populations are more exposed to environmental risk factors, and are usually acquired during childhood. The prevalence of these infections was investigated in the oral cavity of school children with no symptoms of gastric diseases, from a population of Belém-Pa, in relation to some parameters of oral hygiene and health, socioeconomic conditions and genetic susceptibility factors like the ABO and Lewis blood groups. Were investigated 104 patients, with average age of 17 years. Of all the participants were collected saliva samples and dental plaque. Saliva was collected to identify the ABO and Lewis state secretor and estimation of salivary parameters, and both, saliva and plaque samples were collected for molecular analysis of 16S rRNA genes of H. pylori and FUT2. H. pylori was detected in 79.8% of the students, with a frequency of 66.35% in dental plaque and 58.65% in saliva. The caries prevalence was 82.8% in the population studied. The clinical evaluation of oral health showed that the average CPO-D found was 3.53. It was observed that the caries experience tends to increase as in addition to age and the H. pylori infection was higher in early childhood. The education level and number of dentist visits showed significant differences in relation to the presence of H. pylori. The phenotypic distribution of ABO and Lewis blood groups did not differ significantly between infected and uninfected individuals, explaining there is greater genetic susceptibility to infection by H. pylori and dental caries. Throughout this analysis, the high frequencies found prove the need for care and treatment of dental diseases, such as caries and it is suggested that H. pylori in the oral cavity can contribute to infection and re-infection of the stomach after treatment.

Orientador: Ana Elizabete Silva / Banca: Maria Inês Moura Pardini / Banca: Fátima Pereira de Souza / Resumo: O câncer gástrico é a segunda causa de morte por câncer no mundo e o quinto tipo com maior prevalência no Brasil, sendo previstos 21.800 casos novos em 2008. Esta neoplasia apresenta etiologia bastante complexa, envolvendo fatores genéticos e ambientais. Os fatores etiológicos de maiores destaques incluem a infecção pela bactéria Helicobacter pylori, a ingestão de determinados alimentos, como defumados, enlatados e com elevada quantidade de sal, além do estilo de vida dos indivíduos, associado ao consumo de cigarro e álcool. Uma lesão pré-cancerosa importante no desenvolvimento da neoplasia gástrica é a metaplasia intestinal, podendo aumentar o seu risco em até 10 vezes. Atualmente é reconhecida a participação de alterações epigenéticas como metilação aberrante do DNA, que atua de forma igualmente relevante e complementar no processo de desenvolvimento e progressão do câncer. Vários genes com papel importante no controle do ciclo celular, reparo do DNA, apoptose, angiogênese e adesão celular podem apresentar expressão alterada devido metilação aberrante de sua região promotora, assim a investigação do padrão de metilação de genes envolvidos com o processo neoplásico pode ser uma estratégia interessante para a indicação de marcadores moleculares que possam auxiliar no diagnóstico precoce do câncer. Desta forma, no presente trabalho foi investigado o padrão de metilação dos genes WT1 e RARß em metaplasia intestinal (35 amostras) e suas respectivas mucosas gástricas normais, em comparação com o câncer gástrico (8 amostras) também com suas respectivas mucosas normais, através da técnica MS-PCR (Methylation Specific PCR). Devido à participação da infecção pela H. pylori na carcinogênese gástrica, foi investigada molecularmente a presença dessa bactéria nas amostras...(Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Worldwide, the gastric cancer is the second cause of death by cancer. In Brazil, it is the fifth type with more abundant, foreseen 21.800 new cases in 2008. This neoplasia presents very complex etiology involving genetic and environmental factors. The main etiologic factors include: infection by H. pylori, intake of specific foods such as curing food, canned food, and high consumption of salt wealthy food, besides people life style associated to alcohol and cigarette consumptions. An important previous-cankered lesion in development of gastric neoplasia is the intestinal metaplasia, what can increase your risk in ten times. At this moment, it is recognized the participation of epigenetic alterations like ADN aberrant methylation, which actuate in a same way considerable and complementary in development process and cancer evolution. Many genes with important role in control of cellular cycle, ADN repair, apoptosis, angiogenesis and cellular adhesion can present changed expression due aberrant metthylation of your promoter region. In this manner, the investigation of metithyation pattern of genes involved with the neoplasic process can be an interesting strategy for the indication of molecular markers that can help in cancer precocious diagnosis. Thus, in this present study were investigated the metthylation pattern of RARß and WT1genes (35 samples) and their respective normal mucous gastrics by technic MSPCR (Methylation Specific PCR). Due to participation of infection by H. pylori in gastric carcinogenesis, it was too molecular investigated the presence of this bacterium in the studied samples and the possible association with the metthylation pattern presented by both genes. The results showed high pattern of methylation in both valued lesions, that is, 97% and 100%, respectively of methylated samples in metaplasia group ...(Complete abstract click electronic access below) / Mestre

<p>Antibiotic resistance is of current concern. Bacteria have become increasingly resistant to commonly used antibiotics and we are facing a growing resistance problem. The present thesis was aimed at studying the impact of antibiotic treatment on pathogenic bacteria as well as on the normal human microbiota, with focus on resistance development.</p><p>Among the factors that affect the appearance of acquired antibiotic resistance, the mutation frequency and biological cost of resistance are of special importance. Our work shows that the mutation frequency in clinical isolates of <i>Helicobacter pylori</i> was generally higher than for other studied bacteria such as <i>Enterobacteriaceae; </i>¼ of the isolates displayed a mutation frequency higher than<i> Enterobacteriaceae </i>defective<i> </i>mismatch repair mutants and could be regarded as mutator strains.</p><p>In <i>H. pylori</i>, clarithromycin resistance confers a biological cost, as measured by decreased competitive ability of the resistant mutants in mice. In clinical isolates, this cost could be reduced, consistent with compensatory evolution stabilizing the presence of the resistant phenotype in the population. Thus, compensation is a clinically relevant phenomenon that can occur in vivo.</p><p>Furthermore, our results show that clinical use of antibiotics selects for stable resistance in the human microbiota. This is important for several reasons. First, many commensals occasionally can cause severe disease, even though they are part of the normal microbiota. Therefore, stably resistant populations increase the risk of unsuccessful treatment of such infections. Second, resistance in the normal microbiota might contribute to increased resistance development among pathogens by interspecies transfer of resistant determinants.</p>

<p>In recent years molecular biology has become an integral part of the clinical laboratory. With an ever increasing number of methodologies and applications being presented each year it has increased our knowledge of how bacteria cause disease as well as our ability to predict disease outcome. </p><p>The main focus of this thesis has been to develop methods for identifying biomarkers and prediction methods for bacterial infectious diseases by taking advantage of the ever increasing possibilities of molecular biology. We applied cutting edge techniques in order to establish novel platforms for identifying and characterizing biomarkers of disease. </p><p>In paper one we describe a novel approach to measure levels of antibiotic resistance and viability of C. trachomatis, a method that is a clear improvement over existing techniques. In the second paper we describe the development of two assays designed to type pertussis toxin subunit 1 in circulating strains, in order to facilitate multi center studies for vaccine escape surveillance. In paper three we develop a novel microarray application designed to identify a large number of bacterial traits of H. pylori simultaneously with human genetic polymorphisms in order to identify a collection of risk factors that could be used as a prediction tool for gastric cancer risk. In the last paper we define the “antigenome” of H. pylori and identified 14 promising, previously unreported antigens as well as a number of potential biomarkers.</p><p>The platform technologies described in this collection of papers will hopefully help us identifying novel ways of fighting and predicting bacterial disease in future studies. </p>

Antibiotic resistance is of current concern. Bacteria have become increasingly resistant to commonly used antibiotics and we are facing a growing resistance problem. The present thesis was aimed at studying the impact of antibiotic treatment on pathogenic bacteria as well as on the normal human microbiota, with focus on resistance development. Among the factors that affect the appearance of acquired antibiotic resistance, the mutation frequency and biological cost of resistance are of special importance. Our work shows that the mutation frequency in clinical isolates of Helicobacter pylori was generally higher than for other studied bacteria such as Enterobacteriaceae; ¼ of the isolates displayed a mutation frequency higher than Enterobacteriaceae defective mismatch repair mutants and could be regarded as mutator strains. In H. pylori, clarithromycin resistance confers a biological cost, as measured by decreased competitive ability of the resistant mutants in mice. In clinical isolates, this cost could be reduced, consistent with compensatory evolution stabilizing the presence of the resistant phenotype in the population. Thus, compensation is a clinically relevant phenomenon that can occur in vivo. Furthermore, our results show that clinical use of antibiotics selects for stable resistance in the human microbiota. This is important for several reasons. First, many commensals occasionally can cause severe disease, even though they are part of the normal microbiota. Therefore, stably resistant populations increase the risk of unsuccessful treatment of such infections. Second, resistance in the normal microbiota might contribute to increased resistance development among pathogens by interspecies transfer of resistant determinants.

In recent years molecular biology has become an integral part of the clinical laboratory. With an ever increasing number of methodologies and applications being presented each year it has increased our knowledge of how bacteria cause disease as well as our ability to predict disease outcome. The main focus of this thesis has been to develop methods for identifying biomarkers and prediction methods for bacterial infectious diseases by taking advantage of the ever increasing possibilities of molecular biology. We applied cutting edge techniques in order to establish novel platforms for identifying and characterizing biomarkers of disease. In paper one we describe a novel approach to measure levels of antibiotic resistance and viability of C. trachomatis, a method that is a clear improvement over existing techniques. In the second paper we describe the development of two assays designed to type pertussis toxin subunit 1 in circulating strains, in order to facilitate multi center studies for vaccine escape surveillance. In paper three we develop a novel microarray application designed to identify a large number of bacterial traits of H. pylori simultaneously with human genetic polymorphisms in order to identify a collection of risk factors that could be used as a prediction tool for gastric cancer risk. In the last paper we define the “antigenome” of H. pylori and identified 14 promising, previously unreported antigens as well as a number of potential biomarkers. The platform technologies described in this collection of papers will hopefully help us identifying novel ways of fighting and predicting bacterial disease in future studies.

Bacterial pathogens assemble complex surface structures in an attempt to circumvent host immune detection. A great example is the glycolipid known as lipopolysaccharide or lipooligosaccharide (LPS), the major surface molecule in nearly all gram-negative organisms. LPS is anchored to the bacterial cell surface by a anionic hydrophobic lipid known as lipid A, the major agonist of the mammalian TLR4-MD2 receptor and likely target for cationic antimicrobial peptides (CAMPs) secreted by host cells (i.e. defensins). In this work we investigate LPS modification machinery in related ε-proteobacteria, Helicobacter pylori and Campylobacter jejuni, two important human pathogens, and demonstrate that enzymes involved in LPS modification not only play a role in evasion of host defenses but also an unexpected role in bacterial locomotion. More specifically, we identify the enzyme responsible for 4'-dephosphorylation of H. pylori lipid A, LpxF. Demonstrating that lipid A depohsphorylation at the 1 and 4'-positions by LpxE and LpxF, respectively, are the primary mechanisms used by H. pylori for CAMP resistance, contribute to attenuated TRL4-MD2 activation and are required for colonization of a the gastric mucosa in murine host. Similarly in C. jejuni, we identify an enzyme, EptC, responsible for modification of lipid A at both the 1 and 4'-positions with phosphoethanolamine (pEtN), also required for CAMP resistance in this organism. Suprisingly, EptC was found to serve a dual role in modifying not only lipid A with pEtN but also the flagellar rod protein FlgG at residue Thr75, required for motility and efficient flagella production. This work links membrane biogenesis with flagella assembly, both shown to be required for colonization of a host and adds to a growing list of post-translational modifications found in prokaryotes. Understanding how pathogens evade immune detection, interphase with the surrounding environment and assemble major surface features is key in the development of novel treatments and vaccines. / text

Published information on the structure and regulation of H. pylori promoters is limited. The work presented in this thesis describes the cloning and characterisation of promoter regions from a clinical isolate of H. pylori, and the development of an alternative, non-radioactive method for verifying the location of transcriptional start sites of bacterial promoters. H. pylori 4187E promoters were randomly cloned into the promoter-trap vector pKK232-8 in Escherichia coli DH5α using two sets of restriction enzymes. Vector pKK232-8 contains a promoterless chloramphenicol acetyltransferase (CAT) gene. Seventy-four promoter-containing clones were isolated from selective media based on their resistance to chloramphenicol. The strength of each promoter was analysed qualitatively, using chloramphenicol minimum inhibitory concentrations, and quantitatively, using CAT assays following exposure of the clones to pH 4 and pH 7. Selected promoter fragments were subcloned into the GFP reporter vector pFPV25, containing a promoterless gfp gene. The subclones were exposed to buffered LB broth at pH 4, 5, 6, 7 and 8, for varying lengths of time, to study acid-induced regulation of gene expression. Subclones were examined qualitatively, using visual examination of GFP fluorescence and fluorescence microscopy, and quantitatively, using flow cytometry following acid shock. DNA sequences were determined for 61 of the 74 H. pylori promoters, and sequence alignments with the published H. pylori strains (26695 and J99) were performed. The transcriptional start site of 27 H. pylori promoter fragments was experimentally mapped using a fluorescence-based primer extension protocol developed by our group. Potential -35 and -10 sequences were identified for each promoter, and a new consensus sequence for H. pylori promoters was proposed based upon these results. This study has considerably expanded knowledge of H. pylori promoter sequences and transcriptional start sites based on those which also function in E. coli. It has also revealed several H. pylori promoters which appear to respond to acid stress

Submitted by Ayla Blanco Poltronieri null (aylinha_bp@hotmail.com) on 2016-03-11T02:05:30Z No. of bitstreams: 1 Dissertação Pós Defesa.pdf: 1526886 bytes, checksum: b50424a42154b92cbde06c084bf0975d (MD5) / Approved for entry into archive by Sandra Manzano de Almeida (smanzano@marilia.unesp.br) on 2016-03-14T12:33:21Z (GMT) No. of bitstreams: 1 poltronierioliveira_ab_me_sjrp.pdf: 1526886 bytes, checksum: b50424a42154b92cbde06c084bf0975d (MD5) / Made available in DSpace on 2016-03-14T12:33:21Z (GMT). No. of bitstreams: 1 poltronierioliveira_ab_me_sjrp.pdf: 1526886 bytes, checksum: b50424a42154b92cbde06c084bf0975d (MD5) Previous issue date: 2016-03-04 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Introdução: A inflamação crônica desencadeada pela bactéria Helicobacter pylori (H. pylori), a qual é considerada o principal fator ambiental relacionado ao câncer gástrico, está associada ao desenvolvimento e progressão de lesões gástricas pré-cancerosas, desencadeando diversas modificações histológicas e moleculares que promovem a transformação maligna do estômago. Para isso, conta com fatores de virulência que promovem alterações superficiais e em vias de sinalização das células epiteliais gástricas. Consequentemente pode levar a alterações no padrão de expressão de genes supressores tumorais e da atividade de enzimas DNA metil transferases (DNMTs), responsáveis pela metilação do DNA e silenciamento gênico. Objetivos: O presente estudo avaliou se a infecção pela bactéria H. pylori, bem como sua erradicação, altera a expressão do RNAm dos genes supressores SOCS1, RPRM, RUNX3 e dos genes de DNMTs (DNMT1, DNMT3A e DNMT3B) em pacientes com gastrite crônica infectados (Hp+) em comparação com indivíduos com gastrite crônica sem infecção (Hp-). Além disso, investigou a ocorrência de correlação negativa entre a expressão do RNAm dos genes supressores tumorais com a dos genes das DNMTs, assim como a associação dos níveis de expressão gênica em relação aos fatores de risco idade, sexo, tabagismo, etilismo e genótipo bacteriano cagA. Material e Métodos: A quantificação relativa (RQ) do RNAm foi realizada por PCR (polymerase chain reaction) quantitativa em tempo real (qPCR) utilizando ensaios TaqMan® em 9 pacientes com gastrite crônica Hp- e 19 Hp+, sendo estes também avaliados três meses depois da terapia de erradicação bacteriana. O diagnóstico molecular e genotipagem do fator de virulência cagA foram realizados por PCR convencional. Resultados: Os resultados mostraram que a infecção pela H. pylori e sua erradicação não alteraram significantemente a expressão dos genes SOCS1, RPRM, RUNX3 e DNMTs, as quais apresentaram, de modo geral, expressão reduzida (RQ< 1,0), enquanto foi observado expressão mais elevada de SOCS1 e RPRM no grupo sem infecção Hp-. Quanto aos fatores de risco, também não foram encontradas associações significantes com os níveis de expressão dos genes avaliados. A análise de correlação não mostrou correlação negativa da expressão gênica entre os supressores tumorais e as DNMTs, mas evidenciou algumas correlações positivas entre a expressão dos genes SOCS1 e DNMT1 e do RPRM com DNMT3A e DNMT3B no grupo Hp+, que podem ter sido casuais. Conclusão: Nossos resultados não indicam que a infecção causada pela bactéria H. pylori e sua erradicação em pacientes com gastrite crônica afetam a expressão dos supressores tumorais SOCS1, RPRM, RUNX3 e das DNMTs, assim como que seja influenciada pelos fatores idade, sexo, tabagismo, etilismo e genótipo bacteriano cagA. Além disso, a expressão reduzida das DNMTs e ausência de correlação negativa com a dos genes supressores tumorais não permite indicar que a baixa expressão dos genes supressores tumorais seja devido a hipermetilação do DNA em consequência da infecção. / Introduction: Chronic inflammation caused by Helicobacter pylori (H. pylori), which is considered the main environmental factor related to gastric cancer, is associated with the development and progression of precancerous gastric lesions, triggering several histological and molecular changes that promote stomach malignant transformation. For this, it has virulence factors promoting superficial and signaling pathways of gastric epithelial cells changes. Consequently, it can lead to alterations in the expression of tumor suppressor genes and DNA enzyme activity methyl transferases (DNMTs), responsible for DNA methylation and gene silencing. Objectives: This study evaluated whether the infection by the bacterium H. pylori and its eradication change the mRNA expression of suppressor genes SOCS1, RPRM, RUNX3 and DNMTs (DNMT1, DNMT3A and DNMT3B) genes in patients with chronic gastritis infected (Hp+) compared to individuals with chronic gastritis without infection (Hp-). In addition, we investigated the occurrence of negative correlation between mRNA expression of tumor suppressor genes with the ones of DNMTs, as well as the association of gene expression levels in relation to the risk factors age, sex, smoking, drinking and bacterial genotype cagA. Methods: The relative quantification (RQ) mRNA was performed by PCR (polymerase chain reaction) quantitative real-time (qPCR) using TaqMan® assays in 9 patients with chronic gastritis Hp- and 19 Hp+, which are also evaluated three months after bacterial eradication therapy. The molecular diagnostics and genotyping of the virulence factors CagA were performed by standard PCR. Results: The results showed that the infection by H. pylori and eradication did not significantly alter the gene expression of SOCS1, RPRM, RUNX3 and DNMTs, which presented, in general, reduced expression (RQ <1.0); on the other hand, higher expression of SOCS1 and RPRM was observed in the group without Hp- infection. As for risk factors, no significant associations with the expression levels of evaluated genes were found. The correlation analysis not showed a negative correlation of gene expression in the tumor suppressor and DNMTs, but showed some positive correlations between the expression of SOCS1 and DNMT1 genes and RPRM with DNMT3A and DNMT3B the Hp + group, which may have been casual. Conclusion: Our findings do not indicate that the infection caused by the bacterium Helicobacter pylori and its eradication in patients with chronic gastritis affect the expression of tumor suppressor SOCS1, RPRM, RUNX3 and DNMTs, as it is influenced by factors such as age, sex, smoking, alcoholism and bacterial genotype cagA. Furthermore, the reduced expression of DNMTs and no negative correlation with the tumor suppressor genes do not indicate that the low expression of tumor suppressor genes is due to DNA hypermethylation in consequence of infection. / CNPq: 474.776/2013-1 / FAPESP: 2012/15036-8

Made available in DSpace on 2014-06-11T19:26:03Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-02-28Bitstream added on 2014-06-13T18:29:22Z : No. of bitstreams: 1 silva_hm_me_sjrp.pdf: 508031 bytes, checksum: 56b635113c96c5bc5c2ffa3a4cb5324a (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O câncer gástrico é a segunda causa de morte por câncer no mundo e o quinto tipo com maior prevalência no Brasil, sendo previstos 21.800 casos novos em 2008. Esta neoplasia apresenta etiologia bastante complexa, envolvendo fatores genéticos e ambientais. Os fatores etiológicos de maiores destaques incluem a infecção pela bactéria Helicobacter pylori, a ingestão de determinados alimentos, como defumados, enlatados e com elevada quantidade de sal, além do estilo de vida dos indivíduos, associado ao consumo de cigarro e álcool. Uma lesão pré-cancerosa importante no desenvolvimento da neoplasia gástrica é a metaplasia intestinal, podendo aumentar o seu risco em até 10 vezes. Atualmente é reconhecida a participação de alterações epigenéticas como metilação aberrante do DNA, que atua de forma igualmente relevante e complementar no processo de desenvolvimento e progressão do câncer. Vários genes com papel importante no controle do ciclo celular, reparo do DNA, apoptose, angiogênese e adesão celular podem apresentar expressão alterada devido metilação aberrante de sua região promotora, assim a investigação do padrão de metilação de genes envolvidos com o processo neoplásico pode ser uma estratégia interessante para a indicação de marcadores moleculares que possam auxiliar no diagnóstico precoce do câncer. Desta forma, no presente trabalho foi investigado o padrão de metilação dos genes WT1 e RARß em metaplasia intestinal (35 amostras) e suas respectivas mucosas gástricas normais, em comparação com o câncer gástrico (8 amostras) também com suas respectivas mucosas normais, através da técnica MS-PCR (Methylation Specific PCR). Devido à participação da infecção pela H. pylori na carcinogênese gástrica, foi investigada molecularmente a presença dessa bactéria nas amostras... / Worldwide, the gastric cancer is the second cause of death by cancer. In Brazil, it is the fifth type with more abundant, foreseen 21.800 new cases in 2008. This neoplasia presents very complex etiology involving genetic and environmental factors. The main etiologic factors include: infection by H. pylori, intake of specific foods such as curing food, canned food, and high consumption of salt wealthy food, besides people life style associated to alcohol and cigarette consumptions. An important previous-cankered lesion in development of gastric neoplasia is the intestinal metaplasia, what can increase your risk in ten times. At this moment, it is recognized the participation of epigenetic alterations like ADN aberrant methylation, which actuate in a same way considerable and complementary in development process and cancer evolution. Many genes with important role in control of cellular cycle, ADN repair, apoptosis, angiogenesis and cellular adhesion can present changed expression due aberrant metthylation of your promoter region. In this manner, the investigation of metithyation pattern of genes involved with the neoplasic process can be an interesting strategy for the indication of molecular markers that can help in cancer precocious diagnosis. Thus, in this present study were investigated the metthylation pattern of RARß and WT1genes (35 samples) and their respective normal mucous gastrics by technic MSPCR (Methylation Specific PCR). Due to participation of infection by H. pylori in gastric carcinogenesis, it was too molecular investigated the presence of this bacterium in the studied samples and the possible association with the metthylation pattern presented by both genes. The results showed high pattern of methylation in both valued lesions, that is, 97% and 100%, respectively of methylated samples in metaplasia group ...(Complete abstract click electronic access below)