Displaying publications 21 - 34 of 34 in total

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  1. Fulltext Evolutionary history of Helicobacter pylori sequences reflect past human migrations in Southeast Asia
    Breurec S, Guillard B, Hem S, Brisse S, Dieye FB, Huerre M, et al.
    PLoS One, 2011;6(7):e22058.
    PMID: 21818291 DOI: 10.1371/journal.pone.0022058
    The human population history in Southeast Asia was shaped by numerous migrations and population expansions. Their reconstruction based on archaeological, linguistic or human genetic data is often hampered by the limited number of informative polymorphisms in classical human genetic markers, such as the hypervariable regions of the mitochondrial DNA. Here, we analyse housekeeping gene sequences of the human stomach bacterium Helicobacter pylori from various countries in Southeast Asia and we provide evidence that H. pylori accompanied at least three ancient human migrations into this area: i) a migration from India introducing hpEurope bacteria into Thailand, Cambodia and Malaysia; ii) a migration of the ancestors of Austro-Asiatic speaking people into Vietnam and Cambodia carrying hspEAsia bacteria; and iii) a migration of the ancestors of the Thai people from Southern China into Thailand carrying H. pylori of population hpAsia2. Moreover, the H. pylori sequences reflect iv) the migrations of Chinese to Thailand and Malaysia within the last 200 years spreading hspEasia strains, and v) migrations of Indians to Malaysia within the last 200 years distributing both hpAsia2 and hpEurope bacteria. The distribution of the bacterial populations seems to strongly influence the incidence of gastric cancer as countries with predominantly hspEAsia isolates exhibit a high incidence of gastric cancer while the incidence is low in countries with a high proportion of hpAsia2 or hpEurope strains. In the future, the host range expansion of hpEurope strains among Asian populations, combined with human motility, may have a significant impact on gastric cancer incidence in Asia.
    Matched MeSH terms: Helicobacter pylori/genetics*
  2. Clarithromycin resistance and point mutations in the 23S rRNA gene in Helicobacter pylori isolates from Malaysia
    Ho SL, Tan EL, Sam CK, Goh KL
    J Dig Dis, 2010 Apr;11(2):101-5.
    PMID: 20402836 DOI: 10.1111/j.1751-2980.2010.00423.x
    To determine the prevalence of primary clarithromycin resistance amongst Helicobacter pylori (H. pylori) strains in Malaysian patients with gastroduodenal diseases, by using restriction fragment length polymorphism (RFLP) in domain V of 23S rRNA.
    Matched MeSH terms: Helicobacter pylori/genetics*
  3. Distinct cagA EPIYA motifs are associated with ethnic diversity in Malaysia and Singapore
    Schmidt HM, Goh KL, Fock KM, Hilmi I, Dhamodaran S, Forman D, et al.
    Helicobacter, 2009 Aug;14(4):256-63.
    PMID: 19674129 DOI: 10.1111/j.1523-5378.2009.00684.x
    In vitro studies have shown that the biologic activity of CagA is influenced by the number and class of EPIYA motifs present in its variable region as these motifs correspond to the CagA phosphorylation sites. It has been hypothesized that strains possessing specific combinations of these motifs may be responsible for gastric cancer development. This study investigated the prevalence of cagA and the EPIYA motifs with regard to number, class, and patterns in strains from the three major ethnic groups within the Malaysian and Singaporean populations in relation to disease development.
    Matched MeSH terms: Helicobacter pylori/genetics*
  4. The cag PAI is intact and functional but HP0521 varies significantly in Helicobacter pylori isolates from Malaysia and Singapore
    Schmidt HM, Andres S, Nilsson C, Kovach Z, Kaakoush NO, Engstrand L, et al.
    Eur J Clin Microbiol Infect Dis, 2010 Apr;29(4):439-51.
    PMID: 20157752 DOI: 10.1007/s10096-010-0881-7
    Helicobacter pylori-related disease is at least partially attributable to the genotype of the infecting strain, particularly the presence of specific virulence factors. We investigated the prevalence of a novel combination of H. pylori virulence factors, including the cag pathogenicity island (PAI), and their association with severe disease in isolates from the three major ethnicities in Malaysia and Singapore, and evaluated whether the cag PAI was intact and functional in vitro. Polymerase chain reaction (PCR) was used to detect dupA, cagA, cagE, cagT, cagL and babA, and to type vacA, the EPIYA motifs, HP0521 alleles and oipA ON status in 159 H. pylori clinical isolates. Twenty-two strains were investigated for IL-8 induction and CagA translocation in vitro. The prevalence of cagA, cagE, cagL, cagT, babA, oipA ON and vacA s1 and i1 was >85%, irrespective of the disease state or ethnicity. The prevalence of dupA and the predominant HP0521 allele and EPIYA motif varied significantly with ethnicity (p < 0.05). A high prevalence of an intact cag PAI was found in all ethnic groups; however, no association was observed between any virulence factor and disease state. The novel association between the HP0521 alleles, EPIYA motifs and host ethnicity indicates that further studies to determine the function of this gene are important.
    Matched MeSH terms: Helicobacter pylori/genetics*
  5. Fulltext Helicobacter pylori cagA gene variants in Malaysians of different ethnicity
    Mohamed R, Hanafiah A, Rose IM, Manaf MR, Abdullah SA, Sagap I, et al.
    Eur J Clin Microbiol Infect Dis, 2009 Jul;28(7):865-9.
    PMID: 19247698 DOI: 10.1007/s10096-009-0712-x
    We have defined DNA repeat variability in the 3'-terminus of the cagA gene of Helicobacter pylori strains from Malaysian patients of different ethnicities. We identified different alleles based on the EPIYA repeats. cagA types A-B-D and A-B-B-D are more similar to the sequence of Japanese strains, whereas cagA types A-B-C, A-B-C-C, A-B and A-C displayed similarity to strain 26695 sequences. A significant association was found between cagA genotypes and patients' ethnicity, with cagA type A-B-D being predominantly isolated from Chinese patients and cagA type A-B-C from Malays and Indians. Our data further corroborate the possibility that variant biological activity of CagA may affect the host specificity and/or pathogenicity of H. pylori.
    Matched MeSH terms: Helicobacter pylori/genetics*
  6. Helicobacter pylori, ethnicity, and the gastroesophageal reflux disease spectrum: a study from the East
    Rajendra S, Ackroyd R, Robertson IK, Ho JJ, Karim N, Kutty KM
    Helicobacter, 2007 Apr;12(2):177-83.
    PMID: 17309756
    Ethnic differences in gastroesophageal reflux disease (GERD) and its complications as well as racial variations in the prevalence of Helicobacter pylori infection are well documented. Nevertheless, the association between reflux disease, H. pylori, and race has not been adequately explored.
    Matched MeSH terms: Helicobacter pylori/genetics
  7. Role of Helicobacter pylori virulence factor and genotypes in non-ulcer dyspepsia
    Tan HJ, Rizal AM, Rosmadi MY, Goh KL
    J Gastroenterol Hepatol, 2006 Jan;21(1 Pt 1):110-5.
    PMID: 16706821
    The role of Helicobacter pylori (HP) in non-ulcer dyspepsia is debatable. Eradicating HP will help a small group of non-ulcer dyspeptic patients. However, it is unclear which subgroup of patients will benefit from eradication therapy. The aim of the present study was to compare the cagA and cagE status, as well as vacA genotypes, of HP in non-ulcer dyspeptic patients who responded successfully to eradication therapy compared with those patients who did not.
    Matched MeSH terms: Helicobacter pylori/genetics*
  8. Distribution of Helicobacter pylori cagA, cagE and vacA in different ethnic groups in Kuala Lumpur, Malaysia
    Tan HJ, Rizal AM, Rosmadi MY, Goh KL
    J Gastroenterol Hepatol, 2005 Apr;20(4):589-94.
    PMID: 15836708
    There is a geographic variation in Helicobacter pylori (HP) genotypes and virulence factors. Cytotoxin associated genes A (cagA) and E (cagE), and certain vacuolating cytotoxin (vacA) genotypes are associated with peptic ulcer disease (PUD). There is also a different prevalence of PUD among different ethnic groups in Malaysia. The present study compared the distribution of vacA alleles and cagA and cagE status in three ethnic groups residing in Kuala Lumpur, Malaysia, and their association with clinical outcome.
    Matched MeSH terms: Helicobacter pylori/genetics*
  9. cagA gene variants in Malaysian Helicobacter pylori strains isolated from patients of different ethnic groups
    Ramelah M, Aminuddin A, Alfizah H, Isa MR, Jasmi AY, Tan HJ, et al.
    FEMS Immunol. Med. Microbiol., 2005 May 1;44(2):239-42.
    PMID: 15866222
    Helicobacter pylori infection of a distinct subtype of cagA may lead to different pathological manifestation. The aim of this study is to determine the presence of cagA gene and its variants in H. pylori infection among different ethnic groups and its effect on gastroduodenal diseases. Overall detection of cagA among the 205 clinical isolates of H. pylori was 94%. Variations in size of the 3' region of cagA gene were examined among 192 Malaysian H. pylori cagA-positive strains. Results showed that three cagA variants differing in fragment length of PCR products were detected and designated as type A (621-651bp), type B (732-735bp) and type C (525 bp). Although there was no association between any of the cagA subtypes with peptic ulcer disease (p>0.05), an association between cagA subtypes with a specific ethnic group was observed. Specific-cagA subtype A strains were predominantly isolated from Chinese compared to Malays and Indians (p<0.0005), and cagA subtype B strains were predominantly isolated from Malays and Indians compared to Chinese (p<0.05). The cagA type A strains of H. pylori is commonly found in the Chinese patients who have a higher risk of peptic ulcer disease, thus indicating that it could be used as an important clinical biomarker for a more severe infection.
    Matched MeSH terms: Helicobacter pylori/genetics
  10. Fulltext Understanding the dimorphic lifestyles of human gastric pathogen Helicobacter pylori using the SWATH-based proteomics approach
    Loke MF, Ng CG, Vilashni Y, Lim J, Ho B
    Sci Rep, 2016 05 25;6:26784.
    PMID: 27222005 DOI: 10.1038/srep26784
    Helicobacter pylori may reside in the human stomach as two morphological forms: the culturable spiral form and the viable but non-culturable (VBNC) coccoid form. This bacterium transforms from spiral to coccoid under in vitro suboptimal conditions. However, both spiral and coccoid have demonstrated its infectivity in laboratory animals, suggesting that coccoid may potentially be involved in the transmission of H. pylori. To determine the relevance of the coccoid form in viability and infectivity, we compared the protein profiles of H. pylori coccoids obtained from prolonged (3-month-old) culture with that of 3-day-old spirals of two H. pylori standard strains using SWATH (Sequential Window Acquisition of all Theoretical mass spectra)-based approach. The protein profiles reveal that the coccoids retained basal level of metabolic proteins and also high level of proteins that participate in DNA replication, cell division and biosynthesis demonstrating that coccoids are viable. Most interestingly, these data also indicate that the H. pylori coccoids possess higher level of proteins that are involved in virulence and carcinogenesis than their spiral counterparts. Taken together, these findings have important implications in the understanding on the pathogenesis of H. pylori-induced gastroduodenal diseases, as well as the probable transmission mode of this bacterium.
    Matched MeSH terms: Helicobacter pylori/genetics
  11. Fulltext Helicobacter pylori recombinant UreG protein: cloning, expression, and assessment of its seroreactivity
    Khalilpour A, Osman S, Yunus MH, Santhanam A, Vellasamy N, Noordin R
    BMC Res Notes, 2014;7:809.
    PMID: 25406411 DOI: 10.1186/1756-0500-7-809
    Helicobacter pylori is a human pathogen and during the process of infection, antigens from the bacterium elicit strong host humoral immune responses. In our previous report, native H. pylori UreG protein showed good reactivity with sera from H. pylori patients. This study was aimed at producing the recombinant form of the protein (rUreG) and determining its seroreactivities.
    Matched MeSH terms: Helicobacter pylori/genetics*
  12. Association of Malaysian Helicobacter pylori virulence polymorphisms with severity of gastritis and patients' ethnicity
    Alfizah H, Ramelah M, Rizal AM, Anwar AS, Isa MR
    Helicobacter, 2012 Oct;17(5):340-9.
    PMID: 22967117 DOI: 10.1111/j.1523-5378.2012.00956.x
    Polymorphisms of Helicobacter pylori cagA and vacA genes do exist and may contribute to differences in H. pylori infection and gastroduodenal diseases among races in the Malaysian population. This study was conducted to characterize the polymorphisms in H. pylori cagA and vacA in Malaysian population.
    Matched MeSH terms: Helicobacter pylori/genetics*
  13. Fulltext Analysis of PCR-RAPD DNA and antibiotic susceptibility profiles of antrum and corpus isolates of Helicobacter pylori from Malaysian patients
    Norazah A, Rasinah WZ, Zaili Z, Aminuddin A, Ramelah M
    Malays J Pathol, 2009 Jun;31(1):29-34.
    PMID: 19694311 MyJurnal
    This study was conducted to determine whether there was any genetic heterogeneity among Helicobacter pylori strains isolated from the antrum and corpus of the same individual in a Malaysian population and to determine the presence of heterogeneous susceptibility of the isolates by comparing PCR-RAPD and antibiotic profiles. Forty-four H. pylori isolates cultured from the antrum and corpus of 22 patients were analyzed. Antibiotic susceptibility testing was carried out by minimum inhibitory concentration determination, using E-Test method strips. PCR-RAPD was carried out on all the strains and the profiles generated were analysed for cluster analysis. Twenty-nine different PCR-RAPD profiles were observed in the 44 isolates. Fifteen pairs of the isolates from the same patients had the same PCR-RAPD patterns while in 7 pairs, the profiles were different. The strains were clustered into 2 separate clusters at a low coefficient of similarity, where most of the strains were in cluster 1. The degree of similarity was very low among most of the isolates. Most of the patients (16 of 22) were infected with strains that have the same antibiotic susceptibility profiles. Out of these, only 10 pairs shared the same PCR-RAPD and antibiotic profiles. Five pairs of isolates with similar PCR-RAPD profiles differed in their antibiotic profiles due to metronidazole resistance in one of the sites. A large degree of genetic heterogeneity was observed among H. pylori strains circulating among Malaysian patients. An individual patient can be infected with multiple strains and the strains can be antibiotic resistant.
    Matched MeSH terms: Helicobacter pylori/genetics
  14. Multiplex PCR for detection of Helicobacter pylori infection in gastric biopsies with lower inflammatory score
    Fadilah N, Hanafiah A, Razlan H, Wong ZQ, Mohamed Rose I, Rahman MM
    Br J Biomed Sci, 2016 Oct;73(4):180-187.
    PMID: 27922429
    BACKGROUND: No gold standard has yet been established for the diagnosis of H. pylori infection. A multiplex polymerase chain reaction (mPCR) was developed in this study for rapid, sensitive and specific detection of H. pylori from gastric biopsies.

    METHODS: H. pylori infections were determined by in-house rapid urease test (iRUT), culture, histology and multiplex PCR.

    RESULTS: A total of 140 (60.9%) from 230 patients were positive for H. pylori infection. H. pylori were detected in 9.6% (22/230), 17% (39/230), 12.6% (29/230) and 60% (138/230) of biopsy specimens by culture, iRUT, histology and mPCR, respectively. mPCR identified H. pylori infection in 100% of biopsies with positive histology and culture. All biopsies with positive iRUT yielded positive PCR except two cases. mPCR also detected H. pylori in additional 116, 101 and 109 biopsies that were negative by culture, iRUT and histology, respectively. Positive samples by mPCR showed lower average in H. pylori density, activity and inflammation scores. The Indians showed the highest prevalence of H. pylori infection compared to the Chinese and the Malays. In addition, Chinese patients with older age were significantly infected compared to other ethnicities.

    CONCLUSION: PCR was able to detect the highest numbers of positive cases although the lowest average scores were recorded in the activity, inflammatory and H. pylori density.

    Matched MeSH terms: Helicobacter pylori/genetics*
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