Edited by Xu XQ and Wang JH
Published online Dec 15, 2001. doi: 10.3748/wjg.v7.i6.783
Revised: July 19, 2001
Accepted: August 1, 2001
Published online: December 15, 2001
AIM: To study the polymorphism of flagellin A genotype and its significance in Helicobacter pylori (H. pylori).
METHODS: As the template, genome DNA was purified from six clinical isolates of H. pylori from outpatients, and the corresponding flagellin A fragments were amplified by polymerase chain reaction. All these products were sequenced. These sequences were compared with each other, and analyzed by software of FASTA program.
RESULTS: Specific PCR products were amplified from all of these H. pylori isolates and no length divergence was found among them. Compared with each other, the highest ungapped identity is 99.10%, while the lowest is 94.65%. Using FASTA program, the alignments between query and library sequences derived from different H. pylori strains were higher than 90%.
CONCLUSION: The nucleotide sequence of flagellin A in H. pylori is highly conservative with incident divergence. This information may be useful for gene diagnosis and further study on flagellar antigen phenotype.
- Citation: Ji WS, Hu JL, Qiu JW, Peng DR, Shi BL, Zhou SJ, Wu KC, Fan DM. Polymorphism of flagellin A gene in Helicobacter pylori. World J Gastroenterol 2001; 7(6): 783-787
- URL: https://www.wjgnet.com/1007-9327/full/v7/i6/783.htm
- DOI: https://dx.doi.org/10.3748/wjg.v7.i6.783
Helicobacter pylori (H. pylori) is widely distributed among humans. It is the major pathogen for most of the gastric diseases. Several potential virulence factors have been suggested to play a role in Helicobacter pathogenesis, t hose studied in most details including the production of abundant amounts of urease, motility, the expression of cytotoxins and other extracellular enzyme, lipo saccharides and adhesion to tissue-specific receptors[1-12].
Even in the viscous environment, a high degree of motility is conferred by three to six flagellas that extends from one pole of the bacterium. The flagella consist of a basal body that contains the motor and the hook structure, the central filament and a membranous sheath enveloping each filament. Flagellin A is the major molecule of filament and responsible for bacterial motility to most degree in H. pylori[13-15].
According to the data reported previously, the sequence of flagellin A is highly conservative in both amino acid and nucleotide level; flagellin A is one of the major antigens to induce the production of antibody in serum[16-20]. Based on these points, flagellin A may be one of the best alternatives for gene diagnosis and designs of vaccine against H. pylori.
Six H. pylori isolates were offered by the Department of Bacteriology, Xijing Hospital, the Fourth Military Medical University.
Genome DNA as template was purified from H. pylori isolates by using genome DNA purification kits (Shanghai Watson Biotech. LTD). Referring to the complete sequence of flagellin A gene in Genbank (X60746), primers were designed by primer 3 program as follows. Forward primer: 5’-GCGGATAAGGCTATGGATGA-3’; reverse primer: 5’-GATCGCTGCGACTAACCTTC-3’. Amplification was proceeded by two-step polymerase chain reaction; that is: 94 °C for 5 min, 94 °C for 45 s, 68 °C for 1 min, 30 cycles，and then 72 °C for 10 min.
Sequences of PCR products amplified from six H. pylori isolates were compared with each other. One of these sequences was presented and analyzed by FASTA program (version 3.3t07).
Any other sequences were compared with sequence A, the numbers of divergent nucleotides were eighteen, ten, twenty-one, thirteen, and twenty-eight between sequence A and B, A and C, A and D, A and E, and between sequence A and F, respectively (Figure 1).
PCR products including 561 nucleotides each were compared mutually and the identity was calculated as follows. Identity (%) = 1-[100% × number of divergent nucleotides/561 nucleotides]. By comparison, it is found that sequence F has much more divergence from any other sequences, while sequence E has higher alignment with other sequences except sequence F (Table 1).
|Identity (%)||Number of divergent nucleotides (base pairs)|
Sequence A was forwarded to EMBL server, and fifty library sequences were searched and analyzed by FAS TA program. Ten library sequences with highest Z-score were shown here. All these sequences were derived from H. pylori strains and had identity with Sequence A higher than ninety-five percent (Table 2).
|Source of nucleotide sequencein Genbank||Z-score||Identity (%)||Length of compared sequences (base pairs)|
Flagella are well-controlled organelle and essential for microbial motility in many bacterial genera[22-28]. Though much effort has been made to study the polymorphism of flagella in other genera like Salmonella, relatively little was known about that in Helicobacter pylori[29-34]. Recently, genome DNA of several isolates was sequenced, which offered the first structural information and made it possible to do further work. Flagellin A is unique in the known H. pylori database, which means that it has sequence quite different from analogs in other bacteria but high conservative within genus.
H. pylori are genetically highly diverse, the intraspecific free recombination of flagellin A is a frequent incident just as occurred in VacA and CagA [35-43]. Not like the diversity of serotypes in Salmonella or other bacteria, few of specific flagellar serotypes have been found in H. pylori so far [44-47]. The reported sequences of flagellin A were highly conservative and some difference may be caused by different methods. This fact was accordant to the results presented here. In this experiment, a fragment of about four hundred nucleotides in H. pylori flagellin A gene was found highly conservative between the oriental and the occidental.
As the unique pathogen, H. pylori are correlated with almost all of the gastric diseases[48-58]. Therefore, development of new methods to detect and eradicate H. pylori infection has become one of the central tasks to treat most of gastric diseases. The conservatism of flagellin A discovered in this experiment may be very helpful for PCR-based gene diagnosis.
Though the polymorphism of Flagellin in H. pylori was reported previously in some labs, it has not determined whether there are specific flagellar serotypes that may be relevant to the clinical symptoms[59-66]. In this experiment, one of the PCR products was found more divergent than that caused by geographical or ethnic factors. It is still not known whether the polymorphism shown here has influence on the flagellar serotype, motility, virulence or its colonization to gastric mucosa. To be one of the vaccine candidates against H. pylori, more work should be do ne on epitope mapping, analysis of molecular structure, and determination of antigen determinant region as well.
As one of the major known pathogenic factors, much research has been done on H. pylori. In one hand, much work was focused on its influence on gastric physiology, pathogenesis, carcinogenesis, and mutual reaction between host and pathogen; on the other hand, more attention was paid on its clinical aspect involving treatment, detection and prevention[67-84]. Though there have already been some methods to detect and treat H. pylori infection so far, much effort must be made to develop more effective way to deal with these worms.
In summary, the nucleotide sequence of flagellin A in H. pylori is highly co nservative with incident divergence. This character is favorable for PCR-based diagnosis. The significance of the polymorphism in nucleo tide level has not well understood. Further study on the divergent isolate that discovered in this experiment might be helpful to interpret this phenomenon.
|1.||Kamiya S, Yamaguchi H, Osaki T, Taguchi H. A virulence factor of Helicobacter pylori: role of heat shock protein in mucosal inflammation after H. pylori infection. J Clin Gastroenterol. 1998;27 Suppl 1:S35-S39. [PubMed] [DOI]|
|2.||Domingo D, Alarcón T, Sanz JC, Villar H, Hernández JM, Sánchez J, López-Brea M. [The Helicobacter pylori adhesion gene: relation with the origin of the isolates and associated disease]. Enferm Infecc Microbiol Clin. 1999;17:342-346. [PubMed]|
|3.||Yokota Si, Amano Ki, Hayashi S, Kubota T, Fujii N, Yokochi T. Human antibody response to Helicobacter pylori lipopolysaccharide: presence of an immunodominant epitope in the polysaccharide chain of lipopolysaccharide. Infect Immun. 1998;66:3006-3011. [PubMed]|
|4.||Monteiro MA, Chan KH, Rasko DA, Taylor DE, Zheng PY, Appelmelk BJ, Wirth HP, Yang M, Blaser MJ, Hynes SO. Simultaneous expression of type 1 and type 2 Lewis blood group antigens by Helicobacter pylori lipopolysaccharides. Molecular mimicry between H. pylori lipopolysaccharides and human gastric epithelial cell surface glycoforms. J Biol Chem. 1998;273:11533-11543. [PubMed] [DOI]|
|5.||Yamaguchi H, Osaki T, Taguchi H, Hanawa T, Yamamoto T, Fukuda M, Kawakami H, Hirano H, Kamiya S. Growth inhibition of Helicobacter pylori by monoclonal antibody to heat-shock protein 60. Microbiol Immunol. 1997;41:909-916. [PubMed] [DOI]|
|6.||Aspinall GO, Monteiro MA, Shaver RT, Kurjanczyk LA, Penner JL. Lipopolysaccharides of Helicobacter pylori serogroups O: 3 and O: 6--structures of a class of lipopolysaccharides with reference to the location of oligomeric units of D-glycero-alpha-D-manno-heptose residues. Eur J Biochem. 1997;248:592-601. [PubMed] [DOI]|
|7.||Yamaguchi H, Osaki T, Taguchi H, Hanawa T, Yamamoto T, Kamiya S. Induction and epitope analysis of Helicobacter pylori heat shock protein. J Gastroenterol. 1996;31 Suppl 9:12-15. [PubMed]|
|8.||Yamaguchi H, Osaki T, Taguchi H, Hanawa T, Yamamoto T, Kamiya S. Flow cytometric analysis of the heat shock protein 60 expressed on the cell surface of Helicobacter pylori. J Med Microbiol. 1996;45:270-277. [PubMed] [DOI]|
|9.||Aspinall GO, Monteiro MA. Lipopolysaccharides of Helicobacter pylori strains P466 and MO19: structures of the O antigen and core oligosaccharide regions. Biochemistry. 1996;35:2498-2504. [PubMed] [DOI]|
|10.||Burnie JP, al-Dughaym A. The application of epitope mapping in the development of a new serological test for Helicobacter pylori infection. J Immunol Methods. 1996;194:85-94. [PubMed] [DOI]|
|11.||Nagata K, Mizuta T, Tonokatu Y, Fukuda Y, Okamura H, Hayashi T, Shimoyama T, Tamura T. Monoclonal antibodies against the native urease of Helicobacter pylori: synergistic inhibition of urease activity by monoclonal antibody combinations. Infect Immun. 1992;60:4826-4831. [PubMed]|
|12.||Watanabe S, Takagi A, Tada U, Kabir AM, Koga Y, Kamiya S, Osaki T, Miwa T. Cytotoxicity and motility of Helicobacter pylori. J Clin Gastroenterol. 1997;25 Suppl 1:S169-S171. [PubMed] [DOI]|
|13.||Suerbaum S, Josenhans C, Labigne A. Cloning and genetic characterization of the Helicobacter pylori and Helicobacter mustelae flaB flagellin genes and construction of H. pylori flaA- and flaB-negative mutants by electroporation-mediated allelic exchange. J Bacteriol. 1993;175:3278-3288. [PubMed]|
|14.||Kostrzynska M, Betts JD, Austin JW, Trust TJ. Identification, characterization, and spatial localization of two flagellin species in Helicobacter pylori flagella. J Bacteriol. 1991;173:937-946. [PubMed]|
|15.||Josenhans C, Labigne A, Suerbaum S. Comparative ultrastructural and functional studies of Helicobacter pylori and Helicobacter mustelae flagellin mutants: both flagellin subunits, FlaA and FlaB, are necessary for full motility in Helicobacter species. J Bacteriol. 1995;177:3010-3020. [PubMed]|
|16.||Mattsson A, Quiding-Järbrink M, Lönroth H, Hamlet A, Ahlstedt I, Svennerholm A. Antibody-secreting cells in the stomachs of symptomatic and asymptomatic Helicobacter pylori-infected subjects. Infect Immun. 1998;66:2705-2712. [PubMed]|
|17.||Komoriya K, Shibano N, Higano T, Azuma N, Yamaguchi S, Aizawa SI. Flagellar proteins and type III-exported virulence factors are the predominant proteins secreted into the culture media of Salmonella typhimurium. Mol Microbiol. 1999;34:767-779. [PubMed] [DOI]|
|18.||Opazo P, Müller I, Rollán A, Valenzuela P, Yudelevich A, García-de la Guarda R, Urra S, Venegas A. Serological response to Helicobacter pylori recombinant antigens in Chilean infected patients with duodenal ulcer, non-ulcer dyspepsia and gastric cancer. APMIS. 1999;107:1069-1078. [PubMed] [DOI]|
|19.||Andrutis KA, Fox JG, Schauer DB, Marini RP, Li X, Yan L, Josenhans C, Suerbaum S. Infection of the ferret stomach by isogenic flagellar mutant strains of Helicobacter mustelae. Infect Immun. 1997;65:1962-1966. [PubMed]|
|20.||Faulde M, Cremer J, Zöller L. Humoral immune response against Helicobacter pylori as determined by immunoblot. Electrophoresis. 1993;14:945-951. [PubMed] [DOI]|
|21.||Leying H, Suerbaum S, Geis G, Haas R. Cloning and genetic characterization of a Helicobacter pylori flagellin gene. Mol Microbiol. 1992;6:2863-2874. [PubMed] [DOI]|
|22.||Foynes S, Dorrell N, Ward SJ, Zhang ZW, McColm AA, Farthing MJ, Wren BW. Functional analysis of the roles of FliQ and FlhB in flagellar expression in Helicobacter pylori. FEMS Microbiol Lett. 1999;174:33-39. [PubMed] [DOI]|
|23.||Spohn G, Scarlato V. Motility of Helicobacter pylori is coordinately regulated by the transcriptional activator FlgR, an NtrC homolog. J Bacteriol. 1999;181:593-599. [PubMed]|
|24.||Mankoski R, Hoepf T, Krakowka S, Eaton KA. flaA mRNA transcription level correlates with Helicobacter pylori colonisation efficiency in gnotobiotic piglets. J Med Microbiol. 1999;48:395-399. [PubMed] [DOI]|
|25.||Jenks PJ, Foynes S, Ward SJ, Constantinidou C, Penn CW, Wren BW. A flagellar-specific ATPase (FliI) is necessary for flagellar export in Helicobacter pylori. FEMS Microbiol Lett. 1997;152:205-211. [PubMed] [DOI]|
|26.||Porwollik S, Noonan B, O'Toole PW. Molecular characterization of a flagellar export locus of Helicobacter pylori. Infect Immun. 1999;67:2060-2070. [PubMed]|
|27.||Suerbaum S, Brauer-Steppkes T, Labigne A, Cameron B, Drlica K. Topoisomerase I of Helicobacter pylori: juxtaposition with a flagellin gene (flaB) and functional requirement of a fourth zinc finger motif. Gene. 1998;210:151-161. [PubMed] [DOI]|
|28.||Schmitz A, Josenhans C, Suerbaum S. Cloning and characterization of the Helicobacter pylori flbA gene, which codes for a membrane protein involved in coordinated expression of flagellar genes. J Bacteriol. 1997;179:987-997. [PubMed]|
|29.||Wajanarogana S, Sonthayanon P, Wuthiekanun V, Panyim S, Simpson AJ, Tungpradabkul S. Stable marker on flagellin gene sequences related to arabinose non-assimilating pathogenic Burkholderia pseudomallei. Microbiol Immunol. 1999;43:995-1001. [PubMed] [DOI]|
|30.||Germer J, Ryckmann B, Moro M, Hofmeister E, Barthold SW, Bockenstedt L, Persing DH. Quantitative detection of Borrelia burgdorferi with a microtiter-based competitive polymerase chain reaction assay. Mol Diagn. 1999;4:185-193. [PubMed] [DOI]|
|31.||Mimori-Kiyosue Y, Yamashita I, Fujiyoshi Y, Yamaguchi S, Namba K. Role of the outermost subdomain of Salmonella flagellin in the filament structure revealed by electron cryomicroscopy. J Mol Biol. 1998;284:521-530. [PubMed] [DOI]|
|32.||Dauga C, Zabrovskaia A, Grimont PA. Restriction fragment length polymorphism analysis of some flagellin genes of Salmonella enterica. J Clin Microbiol. 1998;36:2835-2843. [PubMed]|
|33.||Jesudason MV, Sridharan G, Arulselvan R, Babu PG, John TJ. Diagnosis of typhoid fever by the detection of anti-LPS & amp; anti-flagellin antibodies by ELISA. Indian J Med Res. 1998;107:204-207. [PubMed]|
|34.||Yamashita I, Hasegawa K, Suzuki H, Vonderviszt F, Mimori-Kiyosue Y, Namba K. Structure and switching of bacterial flagellar filaments studied by X-ray fiber diffraction. Nat Struct Biol. 1998;5:125-132. [PubMed] [DOI]|
|35.||Han SR, Schreiber HJ, Bhakdi S, Loos M, Maeurer MJ. vacA genotypes and genetic diversity in clinical isolates of Helicobacter pylori. Clin Diagn Lab Immunol. 1998;5:139-145. [PubMed]|
|36.||Hou P, Tu ZX, Xu GM, Gong YF, Ji XH, Li ZS. Helicobacter pylori vacA genotypes and cagA status and their relationship to associated diseases. World J Gastroenterol. 2000;6:605-607. [PubMed]|
|37.||Zhang LX, Zhang L, Liu YG, Zhang NX, Yan XJ, Han FC, Hou Y. A case control study on the relationship between Helicobacter pylori expressed cytotoxin associated gene A (CagA) and gastroduodenal ulcer. Shijie Huaren Xiaohua Zazhi. 2000;8:733-736.|
|38.||Qiu JW, Hu JL, Wu KC, Qiao W, Ji WS, Shi Bl, Peng DR, Fan DM. Multiplex PCR in the determination of H. pylori cagA and vacA genotypes. Shijie Huaren Xiaohua Zazhi. 2001;9:34-38.|
|39.||Han FC, Yan XJ, Hou Y, Xiao LY, Guo YH, Su CZ. Gold immunochromatographic assay for anti-Helicobacter pylori antibody. Shijie Huaren Xiaohua Zazhi. 1999;7:743-745.|
|40.||Zhang L, Yan XJ, Zhang LX, Han FC, Zhang NX, Hou H, Liu YG. Seroepidemiological study of Hp and cagA Hp infection. Shijie Huaren Xiaohua Zazhi. 2000;8:389-3 92.|
|41.||Suerbaum S, Smith JM, Bapumia K, Morelli G, Smith NH, Kunstmann E, Dyrek I, Achtman M. Free recombination within Helicobacter pylori. Proc Natl Acad Sci USA. 1998;95:12619-12624. [PubMed] [DOI]|
|42.||Reyrat JM, Pelicic V, Papini E, Montecucco C, Rappuoli R, Telford JL. Towards deciphering the Helicobacter pylori cytotoxin. Mol Microbiol. 1999;34:197-204. [PubMed] [DOI]|
|43.||Peek RM, Blaser MJ, Mays DJ, Forsyth MH, Cover TL, Song SY, Krishna U, Pietenpol JA. Helicobacter pylori strain-specific genotypes and modulation of the gastric epithelial cell cycle. Cancer Res. 1999;59:6124-6131. [PubMed]|
|44.||Kwon HJ, Park KY, Yoo HS, Park JY, Park YH, Kim SJ. Differentiation of Salmonella enterica serotype gallinarum biotype pullorum from biotype gallinarum by analysis of phase 1 flagellin C gene (fliC). J Microbiol Methods. 2000;40:33-38. [PubMed] [DOI]|
|45.||Ohta-Tada U, Takagi A, Koga Y, Kamiya S, Miwa T. Flagellin gene diversity among Helicobacter pylori strains and IL-8 secretion from gastric epithelial cells. Scand J Gastroenterol. 1997;32:455-459. [PubMed] [DOI]|
|46.||Schuster SC, Bauer M, Kellermann J, Lottspeich F, Baeuerlein E. Nucleotide sequence of the Wolinella succinogenes flagellin, which contains in the antigenic domain two conserved regions also present in Campylobacter spp. and Helicobacter pylori. J Bacteriol. 1994;176:5151-5155. [PubMed]|
|47.||Penn CW, Luke CJ. Bacterial flagellar diversity and significance in pathogenesis. FEMS Microbiol Lett. 1992;100:331-336. [PubMed] [DOI]|
|48.||Wang CD, Huang HH, Chen YL. Effect of Helicobacter pylori infection on antral G and D cells in patients with active duodenal ulcer. Shijie Huaren Xiaohua Zazhi. 2000;8:847-850.|
|49.||Yang Y, Deng CS, Yao XJ, Liu HY, Chen M. Effect of Helicobacter pylori on morpho logy and growth of gastric epithelial cells. Shijie Huaren Xiaohua Zazhi. 2000;8:500-504.|
|50.||Quan J, Fan XG. Progress in experimental research of Helicobacter pylori infection and gastric carcinoma. Shijie Huaren Xiaohua Zazhi. 1999;7:1068-1069.|
|51.||Guo CQ, Wang YP, Liu GY, Ma SW, Ding GY, Li JC. Study on Helicobacter pylori infection and p53, c-erbB-2 gene expression in carcinogenesis of gastric mucosa. Shijie Huaren Xiaohua Zazhi. 1999;7:313-315.|
|52.||Xu CD, Chen SN, Jiang SH, Xu JY. Seroepidemiology of Helicobacter pylori infection among asymptomatic Chinese children. World J Gastroenterol. 2000;6:759-761. [PubMed]|
|53.||Gao H, Wang JY, Shen XZ, Liu JJ. Effect of Helicobacter pylori infection on gastric epithelial cell proliferation. World J Gastroenterol. 2000;6:442-444. [PubMed]|
|54.||Zhang WD, Wang XH, Zeng JZ, Zhang YL, Sun Y. The relationship of traditional Chinese medicine and Helicobacter pylori infection, expression of oncogene and tumor suppresser genes in patients with gastric cancer and precancerous lessions. World J Gastroenterol. 2000;6:71.|
|55.||Zhuang XQ, Lin SR. Research of Helicobacter pylori infection in precancerous gastric lesions. World J Gastroenterol. 2000;6:428-429. [PubMed]|
|56.||Pace F, Porro GB. Gastroesophageal reflux and Helicobacter pylori: a review. World J Gastroenterol. 2000;6:311-314. [PubMed]|
|57.||Vandenplas Y. Helicobacter pylori infection. World J Gastroenterol. 2000;6:20-31. [PubMed]|
|58.||Zhang H, Jiang SL, Yao XX. Study of T-lymphocyte subsets, nitric oxide, hexosamine and Helicobacter pylori infection in patients with chronic gastric diseases. World J Gastroenterol. 2000;6:601-604. [PubMed]|
|59.||O'Toole PW, Kostrzynska M, Trust TJ. Non-motile mutants of Helicobacter pylori and Helicobacter mustelae defective in flagellar hook production. Mol Microbiol. 1994;14:691-703. [PubMed] [DOI]|
|60.||Eaton KA, Suerbaum S, Josenhans C, Krakowka S. Colonization of gnotobiotic piglets by Helicobacter pylori deficient in two flagellin genes. Infect Immun. 1996;64:2445-2448. [PubMed]|
|61.||Hurtado A, Owen RJ, Desai M. Flagellin gene profiling of Helicobacter pylori infecting symptomatic and asymptomatic individuals. Res Microbiol. 1994;145:585-594. [PubMed] [DOI]|
|62.||Forbes KJ, Fang Z, Pennington TH. Allelic variation in the Helicobacter pylori flagellin genes flaA and flaB: its consequences for strain typing schemes and population structure. Epidemiol Infect. 1995;114:257-266. [PubMed] [DOI]|
|63.||Akopyanz N, Bukanov NO, Westblom TU, Berg DE. PCR-based RFLP analysis of DNA sequence diversity in the gastric pathogen Helicobacter pylori. Nucleic Acids Res. 1992;20:6221-6225. [PubMed] [DOI]|
|64.||Suerbaum S, Geis G, Josenhans C, Opferkuch W. Biochemical studies of Helicobacter mustelae fatty acid composition and flagella. Infect Immun. 1992;60:1695-1698. [PubMed]|
|65.||Hua JS, Zheng PY, Bow H. Species differentiation and identification in the genus of Helicobacter. World J Gastroenterol. 1999;5:7-9. [PubMed]|
|66.||Josenhans C, Ferrero RL, Labigne A, Suerbaum S. Cloning and allelic exchange mutagenesis of two flagellin genes of Helicobacter felis. Mol Microbiol. 1999;33:350-362.|
|67.||Luo YQ, Teng JB, Pan BR, Zhang XY. Liver disease and Helicobacter. World J Gastroenterol. 1999;5:338-334. [PubMed]|
|68.||Wu XN. Current concept of pathogenesis of severe acute pancreatitis. World J Gastroenterol. 2000;6:32-36. [PubMed] [DOI]|
|69.||Hua JS, Bow H, Zheng PY, Khay-Guan Y. Prevalence of primary Helicobacter pylori resistance to metronidazole and clarithromycin in Singapore. World J Gastroenterol. 2000;6:119-121. [PubMed] [DOI]|
|70.||Liu HF, Liu WW, Fang DC, Yang SM, Zhao L. Gastric epithelial apoptosis induced byHelicobacter pylori and its relationship with Bax protein expression. Shi jie. Huaren Xiaohua Zazhi. 2000;8:860-862.|
|71.||Chi J, Lu M, Fu BY, Nakajima S, Hattori T. The effect of mast cell on the induction of Helicobacter pylori infection in Mongolian gerbils. World J Gastroenterol. 2000;6:440-441. [PubMed]|
|72.||Cai Q, Chow A. Carbon 14 urea breath test: a cost effective tool for evaluation of Helicobacter pylori eradication. World J Gastroenterol. 2000;6:8.|
|73.||Byrd JC, Bresalier RS. Alterations in gastric mucin synthesis by Helicobacter pylori. World J Gastroenterol. 2000;6:13.|
|74.||Byrd JC, Bresalier RS. Alterations in gastric mucin synthesis by Helicobacter pylori. World J Gastroenterol. 2000;6:475-482. [PubMed]|
|75.||Pena A. Genetic factors determining the host response to Helicobacter pylori. World J Gastroenterol. 2000;6:624-625. [PubMed]|
|76.||Zhang WD, Wang XH, Zeng JZ, Zhang YL, Sun Y. The relationship of traditional Chi nese medicine and Helicobacter pylori infection, expression of oncogene and tumor suppresser genes in patients with gastric cancer and precancerous lesions. World J Gastroenterol. 2000;6:71.|
|77.||Yang ZB, Wang PL, Gu MM, Chen LH, Chen Q, Zhan L. Diagnostic value of CagA IgG in the process to eradicate Helicobacter pylori. World J Gastroenterol. 2000;6:70. [DOI]|
|78.||Zhuang XQ, Lin SR. Research of Helicobacter pylori infection in precancerous gastric lesions. World J Gastroenterol. 2000;6:428-429. [PubMed]|
|79.||Cai L, Yu SZ, Zhang ZF. Helicobacter pylori infection and risk of gastric cancer in Changle County, Fujian Province, China. World J Gastroenterol. 2000;6:374-376. [PubMed]|
|80.||Khin MM, Hua JS, Ng HC, Wadstrom T, Bow H. Agglutination of Helicobacter pylori coccoids by lectins. World J Gastroenterol. 2000;6:202-209. [PubMed]|
|81.||Lu SY, Pan XZ, Peng XW, Shi ZL. Infection of Helicobacter pylorus and proliferation and apoptosis of gastric mucosa epithelium. Shijie Huaren Xiaohua Zazhi. 1999;7:975-977.|
|82.||Guo HY, Zhang JZ. Recent progress on the adhesions of Helicobacter pylori. Shijie Huaren Xiaohua Zazhi. 2000;8:690-692.|
|83.||Xu ZM, Zhou DY, Pan LJ, Song S. Transformation and reversion of Helicobacter pylori in vitro. Shijie Huaren Xiaohua Zazhi. 1999;7:215-217.|
|84.||Guan J, Zhang JP, Zhou TH. Relationship between telomerase Helicobacter pylori and stomach cancer. Shijie Huaren Xiaohua Zazhi. 2000;8:910-911.|