Rui M Ferreira

University of Porto, Oporto, Porto, Portugal

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Publications (12)76.42 Total impact

  • Rui M Ferreira, José C Machado, Ceu Figueiredo
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    ABSTRACT: Helicobacter pylori infection is the major etiological factor of gastric carcinoma. This disease is the result of a long, multistep, and multifactorial process, which occurs only in a small proportion of patients infected with H. pylori. Gastric carcinoma development is influenced by host genetic susceptibility factors, environmental factors, and H. pylori virulence. H. pylori is genetically highly variable, and variability that affects H. pylori virulence factors may be useful to identify strains with different degrees of pathogenicity. This review will focus on VacA and CagA that have polymorphic regions that impact their functional properties. The characterization of H. pylori vacA and cagA-associated could be useful for identifying patients at highest risk of disease, who could be offered H. pylori eradication therapy and who could be included in programs of more intensive surveillance in an attempt to reduce gastric carcinoma incidence. Copyright © 2014 Elsevier Ltd. All rights reserved.
    Baillière&#x027 s Best Practice and Research in Clinical Gastroenterology 12/2014; 28(6):1003-1015. DOI:10.1016/j.bpg.2014.09.004 · 3.28 Impact Factor
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    ABSTRACT: First-degree relatives (FDR) of early-onset gastric cancer (EOGC) is presumed to be a population with a distinct molecular and phenotypic profile, regarding the prevalence of gastric premalignant conditions and the association with Helicobacter pylori infection and host proinflammatory gene polymorphisms. A case-control study was conducted with FDR of EOGC patients (n = 103) and age and gender matched controls (n = 101; ranging from spouses to neighbors and dyspeptics). Upper endoscopy was performed, Operative Link on Gastritis Assessment (OLGA) system used for staging and H. pylori (cagA and vacA) and host IL1B-511, IL1RN intron2 VNTR and IFNGR1-56 genotyping. Seventy percent of cases showed atrophy, while 19 % presented with high-stage gastritis (OLGA stage III or IV) (p < 0.001); gastric dysplasia was present in seven cases (vs none in controls) (p = 0.007). In cases, H. pylori was present in 82 % (vs 62 % in controls; p = 0.004) with vacA s1 and vacA m1 + strains significantly associated with the presence of atrophy; individuals homozygous for IL1B-511*T present a significantly higher risk for dysplasia. An increased global prevalence of IFNGR1-56*T/*T polymorphism (37 % in cases vs 24 % in controls; p = 0.03) was observed with no association with atrophic changes or dysplasia. All trends observed were kept when comparing FDR of EOGC with spouses, neighbors, or dyspeptic controls. We demonstrated that FDR of EOGC patients have an increased prevalence of high-risk OLGA stages and dysplasia that seem to be associated with high virulence H. pylori strains and pro-inflammatory host genotypes, including a possible population-specific risk marker. FDR of EOGC patients may merit specific management through endoscopic and histopathological adequate assessment of gastric mucosa and surveillance.
    Archiv für Pathologische Anatomie und Physiologie und für Klinische Medicin 07/2013; DOI:10.1007/s00428-013-1458-5 · 2.56 Impact Factor
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    ABSTRACT: In here, we evaluated a previously established PNA-FISH method as a new diagnostic test for H. pylori clarithromycin resistance detection in paraffin embedded gastric biopsies. Both a retrospective and a prospective cohort study were conducted to evaluate the specificity and sensitivity of a PNA-FISH method to determine H. pylori clarithromycin resistance. In the retrospective study (n=30 patients), full agreement between PNA-FISH and PCR-sequencing was observed. When compared to the reference method (culture followed by Etest®), specificity and sensitivity of PNA-FISH were 90.9% (95% confidence interval [CI], 57.1-99.5%) and 84.2% (95% CI, 59.5-95.8%), respectively. In the prospective cohort (n=93 patients), 21 cases were positive by culture. For the patients harboring clarithromycin-resistant H. pylori, the method showed a sensitivity of 80.0% (95% CI, 29.9-98.9%) and specificity of 93.8% (95% CI, 67.7-99.7%). These values are likely to be underestimated, as in some discrepant results patients were infected by more than one strain. PNA-FISH appears to be a simple, quick and an accurate method for detecting H. pylori clarithromycin resistance in paraffin embedded biopsies. It is also the only one of the methods assessed here that allows direct and specific visualization of this microorganism within the biopsies, a characteristic that allowed observing that different H. pylori strains can subsist very closely in the stomach.
    Journal of clinical microbiology 04/2013; DOI:10.1128/JCM.00302-13 · 4.23 Impact Factor
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    ABSTRACT: The present report describes a novel method for genotyping the virulence-associated vacA intermediate (i) region of Helicobacter pylori in archive material.vacA i-region genotypes as determined by the novel method, were completely concordant with those of sequence analysis and with those of functional vacuolation activity. The method was further validated directly in gastric biopsy specimens of 386 H. pylori-positive cases, and effective characterization of the vacA i-region was obtained in 191 of 192 (99.5%) frozen and in 186 of 194 (95.9%) formalin-fixed paraffin-embedded gastric biopsy specimens, respectively.The genotyping method was next used to address the relationship between the vacA genotypes and the cagA status. The vacA i1 genotype was associated with vacA s1, vacA m1 and cagA-positive genotypes (P < 0.0001), while the vacA i2 genotype was closely related with vacA s2, vacA m2 and cagA-negative genotypes (P < 0.0001).The relationship between H. pylori vacA i-region genotypes and gastric disease development was subsequently evaluated in the Portuguese population. Patients infected with vacA i1 strains showed an increased risk for gastric atrophy and for gastric carcinoma with odds ratio of 8.0 (95%, CI 2.3-27) and of 22 (95%, CI 7.9-63), respectively.Taken together, the results show that this novel H. pylori vacA i-region genotyping method can be applied directly to archive material, providing a fast evaluation of strain virulence determinants without the need of culture. The results further emphasize that the characterization of the vacA i-region may be useful to identify patients at higher risk of gastric carcinoma development.
    Journal of clinical microbiology 10/2012; 50(12). DOI:10.1128/JCM.02087-12 · 4.23 Impact Factor
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    ABSTRACT: H. pylori drug-resistant strains and non-compliance to therapy are the major causes of H. pylori eradication failure. For some bacterial species it has been demonstrated that fatty acids have a growth inhibitory effect. Our main aim was to assess the ability of docosahexaenoic acid (DHA) to inhibit H. pylori growth both in vitro and in a mouse model. The effectiveness of standard therapy (ST) in combination with DHA on H. pylori eradication and recurrence prevention success was also investigated. The effects of DHA on H. pylori growth were analyzed in an in vitro dose-response study and n in vivo model. We analized the ability of H. pylori to colonize mice gastric mucosa following DHA, ST or a combination of both treatments. Our data demonstrate that DHA decreases H. pylori growth in vitro in a dose-dependent manner. Furthermore, DHA inhibits H. pylori gastric colonization in vivo as well as decreases mouse gastric mucosa inflammation. Addition of DHA to ST was also associated with lower H. pylori infection recurrence in the mouse model. In conclusion, DHA is an inhibitor of H. pylori growth and its ability to colonize mouse stomach. DHA treatment is also associated with a lower recurrence of H. pylori infection in combination with ST. These observations pave the way to consider DHA as an adjunct agent in H. pylori eradication treatment.
    PLoS ONE 04/2012; 7(4):e35072. DOI:10.1371/journal.pone.0035072 · 3.53 Impact Factor
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    ABSTRACT: To characterize the variation in virulence of Helicobacter pylori associated with CagA Glu-Pro-Ile-Tyr-Ala (EPIYA) motifs, and to explore its relationship with the histopathological features of chronic gastritis and with the development of gastric carcinoma. A total of 169 H. pylori-infected patients with chronic gastritis and gastric carcinoma were studied. The presence of cagA and the number and type of EPIYA motifs were determined by polymerase chain reaction. Infection with strains harbouring two or more CagA EPIYA C motifs was associated with the presence of surface epithelial damage, and with atrophic gastritis and gastric carcinoma. The magnitude of risk for atrophic gastritis and gastric carcinoma increased with increasing number of EPIYA C motifs: strains with one EPIYA C motif conferred a risk (odds ratio [OR]) of 7.3 [95% confidence interval (CI) 2.1-25] for atrophic gastritis, whereas strains with two or more EPIYA C motifs conferred a risk (OR) of 12 (95% CI 2.5-58); strains with one EPIYA C motif conferred a risk (OR) of 17 (95% CI 5.4-55) for gastric carcinoma, whereas strains with two or more EPIYA C motifs conferred a risk (OR) of 51 (95% CI 13-198). Characterization of the number of H. pylori EPIYA C motifs is important in better defining gastric carcinoma risk.
    Histopathology 02/2012; 60(6):992-8. DOI:10.1111/j.1365-2559.2012.04190.x · 3.30 Impact Factor
  • The American Journal of Gastroenterology 01/2012; 107(1):145-6. DOI:10.1038/ajg.2011.389 · 9.21 Impact Factor
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    ABSTRACT: Triple therapy is the gold standard treatment for Helicobacter pylori eradication from the human stomach, but increased resistance to clarithromycin became the main factor of treatment failure. Until now, fastidious culturing methods are generally the method of choice to assess resistance status. In this study, a new genotypic method to detect clarithromycin resistance in clinical samples, based on fluorescent in situ hybridization (FISH) using a set of peptide nucleic acid probes (PNA), is proposed. The set of probes targeting the point mutations responsible for clarithromycin resistance was applied to H. pylori suspensions and showed 100% sensitivity and specificity (95% CI, 79.9-100 and 95% CI, 71.6-100 respectively). This method can also be amenable for application to gastric biopsy samples, as resistance to clarithromycin was also detected when histological slides were tested. The optimized PNA-FISH based diagnostic method to detect H. pylori clarithromycin resistance shown to be a very sensitive and specific method for the detection of clarithromycin resistance in the H. pylori smears and also proved to be a reliable method for the diagnosis of this pathogen in clinical samples and an alternative to existing plating methods.
    BMC Microbiology 05/2011; 11:101. DOI:10.1186/1471-2180-11-101 · 2.98 Impact Factor
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    ABSTRACT: The transmission of the gastric pathogen Helicobacter pylori involves the oral route. Molecular techniques have allowed the detection of H. pylori DNA in samples of the oral cavity, although culture of H. pylori from these type of samples has been sporadic. Studies have tried to demonstrate the presence of H. pylori in adenotonsillar tissue, with contradictory results. Our aim was to clarify whether the adenotonsillar tissue may constitute an extra gastric reservoir for H. pylori. Sixty-two children proposed for adenoidectomy or tonsillectomy were enrolled. A total of 101 surgical specimens, 55 adenoid and 46 tonsils, were obtained. Patients were characterized for the presence of anti-H. pylori antibodies by serology. On each surgical sample rapid urease test, immunohistochemistry, fluorescence in situ hybridization (FISH) with a peptide nucleic acid probe for H. pylori, and polymerase chain reaction-DNA hybridization assay (PCR-DEIA) directed to the vacA gene of H. pylori were performed. Thirty-nine percent of the individuals had anti-H. pylori antibodies. Rapid urease test was positive in samples of three patients, all with positive serology. Immunohistochemistry was positive in samples of two patients, all with negative serology. All rapid urease test or immunohistochemistry positive cases were negative by FISH. All samples tested were negative when PCR-DEIA for H. pylori detection was used directly in adenotonsillar specimens. The adenotonsillar tissue does not constitute an extra gastric reservoir for H. pylori infection, at least a permanent one, in this population of children. Moreover, techniques currently used for detecting gastric H. pylori colonization are not adequate to evaluate infection of the adenotonsillar tissues.
    International journal of pediatric otorhinolaryngology 05/2010; 74(7):807-11. DOI:10.1016/j.ijporl.2010.04.007 · 1.32 Impact Factor
  • Gastroenterology 05/2009; 136(5). DOI:10.1016/S0016-5085(09)62519-1 · 13.93 Impact Factor
  • Gastroenterology 05/2009; 136(5). DOI:10.1016/S0016-5085(09)62525-7 · 13.93 Impact Factor
  • Gastroenterology 04/2008; 134(4). DOI:10.1016/S0016-5085(08)62642-6 · 13.93 Impact Factor

Publication Stats

59 Citations
76.42 Total Impact Points


  • 2010–2014
    • University of Porto
      • Institute of Molecular Pathology and Immunology (IPATIMUP)
      Oporto, Porto, Portugal
  • 2012
    • University of Nottingham
      • Nottingham Hearing Biomedical Research Unit
      Nottigham, England, United Kingdom