不同疾病来源幽门螺杆菌菌株对人胃癌细胞系AGS基质金属蛋白酶表达影响的比较研究

背景：幽门螺杆菌（H.pylori）是胃癌的Ⅰ类致癌原，但H.pylori感染与胃癌发生的分子机制仍不明了。目的：在体外观察不同疾病来源的H.pylori菌株对人胃癌细胞系AGS基质金属蛋白酶（MMPs）表达的影响是否存在差异。方法：将AGS细胞分别与5株分离自胃癌和5株分离自轻度非萎缩性胃炎患者的H.pylori共培养，以逆转录聚合酶链反应（RT-PCR）和蛋白质印迹法（Western blot）检测MMP-2、MMP-7和MMP-9 mRNA和蛋白的表达，以肠道致病性大肠杆菌作为细菌对照。结果：胃炎H.pylori菌株和大肠杆菌基本不影响AGS细胞MMP-2、MMP-7和MMP-9 mRNA和蛋白的表达，而所有胃癌菌株均能上调MMP-2、MMP-7和MMP-9 mRNA和蛋白的表达。结论：分离自胃癌和胃炎患者的H.pylori菌株对AGS细胞MMP-2、MMP-7和MMP-9表达的影响有所不同，说明不同疾病来源的H.pylori菌株在促细胞恶变能力上存在差异。     

幽门螺杆菌对AGS细胞DNA错配修复基因表达的影响

目的体外观察幽门螺杆菌对AGS细胞DNA错配修复（mismatch repair，MMR）基因蛋白和mRNA表达的影响，以确定不同疾病来源幽门螺杆菌对MMR基因表达的影响是否存在差异。方法AGS细胞分别与5株分离自胃癌和5株分离自胃炎患者的幽门螺杆菌共培养。逆转录一聚合酶链反应（RT—PCR）和Western印迹法检测hMSH2和hMLH1基因mRNA和蛋白表达，同时以肠道致病性大肠杆菌作为细菌对照。结果胃炎菌株和大肠杆菌基本不影响hMLH1和hMSH2基因mRNA和蛋白表达，而所有胃癌菌株都能下调hMLH1和hMSH2基因mRNA和蛋白表达。结论胃癌菌株与胃炎菌株对胃癌细胞MMR的影响存在差异，提示部分幽门螺杆菌菌株可能通过损害细胞MMR功能促进胃黏膜上皮细胞内DNA突变累积，增加幽门螺杆菌长期感染时胃癌发生的危险性。     

不同种族幽门螺杆菌菌株CagA蛋白羧基端结构和生物学功能的差异

目的比较不同种族H.pylori菌株CagA蛋白羧基端结构以及诱导AGS细胞延伸、分泌IL-8能力的差异。方法 PCR扩增CagA3′端可变区DNA序列并进行测序,获得CagA3′端可变区氨基酸序列。以不同H.pylori菌株与AGS细胞孵育,观察AGS延伸细胞的百分数,测定细胞培养上清IL-8含量。结果美籍亚裔和美籍非裔菌株的CagA羧基端氨基酸第3个EPIYA前后的氨基酸序列存在明显差异。不同种族cag PAI+H.pylori导致AGS细胞延伸、分泌IL-8能力无明显差异。cag PAI+H.pylori诱导细胞延伸AGS细胞、分泌IL-8的能力明显大于cag PAI-H.pylori。结论不同种族H.pylori菌株CagA蛋白羧基端结构存在差异。H.py-lori菌株诱导AGS细胞延伸、分泌IL-8的能力与cag PAI有关。     

CagA对AGS细胞Ca2+相关蛋白磷酸化的影响

目的:分析幽门螺杆菌(H pllori)细胞毒素相关蛋白A(CagA)对人胃腺癌黏膜上皮细胞(AGS)Ca2 相关蛋白磷酸化的影响,进一步揭来H pylori的致病机制.方法:采用金属离子亲和吸附富集技术富集H pylori、H pylori CagA缺失株(H pylori △CagA)与AGs细胞相互作用4 h,以及培养相同时间的AGS细胞的磷酸化蛋白.利用二维凝胶电泳技术分离磷酸化蛋白,ImageMaster 2D分析软件识别差异蛋白,MALDI-TOF/OF质谱鉴定确认蛋白.结果:Hpylozi △ CagA作用的AGS细胞.与培养相同时间的AGS细胞比较表达量不变,而Hpylori △CagA作用的AGS细胞表达量发生了明显变化,表明此蛋白的变化是单纯由CagA引起的;此类蛋白点共鉴定出19个,其中3个蛋白点与Ca2 相关.钙离子结合蛋白(nucleobindin-2 precursor,CALNUC)在AGS细胞以及H pylori △CagA与AGS相互作用的2-D胶中表达量接近,而H pylori与AGS相互作用后该蛋白表达量明显降低.结论:H pylori △CagA进AAGS细胞可能会影响内质网、线粒体及高尔基体的钙稳态,诱发内质网、线粒体、高尔基体凋亡或增殖途径.而成为胃炎、胃溃疡、胃癌发生的诱因之一.     

幽门螺杆菌对人胃癌细胞株AGS侵袭力的影响

背景：幽门螺杆菌（H．pylori）为人类胃癌的Ⅰ类致癌原,但其在胃癌演进中的作用仍未完全阐明。目的：体外观察Hpylori对人胃癌细胞株AGS侵袭力的影响。方法：将AGS细胞与H．pylori标准菌株NCTC11637共培养72h．光学显微镜观察12—72h时细胞形态变化,扫描电镜观察24h时细胞形态变化。侵袭小室实验检测共培养24h后AGS细胞的侵袭力。结果：AGS细胞与H．pylori共培养12h后,细胞渐出现变形,伪足增多、伸长．24h和48h时细胞间相互离散,伸出细长伪足,呈“蜂鸟”表型,60h和72h时细胞出现空泡样变,死亡逐渐增多;扫描电镜下可见Hpylori黏附于AGS细胞表面,细胞变形明显,伸出细长伪足。侵袭小室实验显示与H．pylori共培养24h的AGS细胞,每200倍视野下穿膜细胞数显著高于PBS对照组（130．4±11．5对87．1±9．3．P〈0．01）。结论：Mpylori感染可影响人胃癌细胞株AGS的细胞形态,增加细胞侵袭力。     

不同胃疾病来源幽门螺杆菌菌株PPIase编码基因分布频率及其意义

目的:探讨肽酰-脯氨酰-顺反式异构酶(peptidyl-prolyl cis-trans isomerase,PPIase)编码基因在不同胃疾病来源幽门螺杆菌(Helicobacter pylori,H.pylori)菌株中的分布情况,旨在揭示其在胃疾病动态发展过程中的作用及其与胃疾病相关性.方法:选取浅表性胃炎(superficial gastritis,GS)、萎缩性胃炎(atrophic gastritis,GA)、胃癌(gastric cancer,GC)三组疾病来源胃黏膜活检标本分离培养出的H.pylori菌株64例,其中GS26例、GA18例、GC20例,使用酚-氯仿法提取菌种DNA,经聚合酶链反应及琼脂糖凝胶电泳对PPIase编码基因进行检测.用2检验或Fisher精确检验分析不同胃疾病来源H.pylori菌株PPIase编码基因分布频率差异.结果:GA组来源的H.pylori菌株PPIase基因分布频率(94.4%)最高,与GS组(57.7%)和GC组(65.0%)相比差异有统计学意义(P=0.014,P=0.045);GC组(65.0%)PPIase基因分布频率高于GS组(57.7%),无统计学差异(P>0.05).结论:萎缩性胃炎来源H.pylori菌株携带较高频率PPIase编码基因,其与萎缩性胃炎的发生密切相关.     

人胃上皮细胞中幽门螺杆菌CagA相关未知磷酸化蛋白和磷酸化位点分析

背景：细胞毒素相关基因A蛋白（CagA）是Ⅰ型幽门螺杆菌（H.pylori）的主要毒力因子。H.pylori胃癌、胃炎相关株和CagA缺失（△CagA）株的蛋白质组学研究尚未发现CagA相关生物标记蛋白。目的：分析H.pyloriCagA阳性株和△CagA株作用后人胃上皮细胞中差异表达的未知磷酸化蛋白和磷酸化位点,为研究CagA的致病机制提供线索。方法：以金属离子亲和吸附富集技术富集经H.pylori标准株和△CagA株作用4h的人胃腺癌细胞株AGS的磷酸化蛋白,双向电泳（2-DE）分离蛋白,飞行时间质谱（TOF-MS）技术鉴定差异蛋白点。结果：H.pylori标准株作用后,AGS细胞FAM50A蛋白276位丝氨酸发生磷酸化,PQBP1蛋白227～251序列中有磷酸化位点。与H.pylori标准株相比,△CagA株作用于AGS细胞可引起至少13种未知磷酸化蛋白的变化,其质谱图中均出现中性丢失峰,其中2种表达量增加,4种表达量降低,6种消失,1种新发生磷酸化。结论：CagA阳性H.pylori感染可致AGS细胞FAM50A和PQBP1蛋白发生磷酸化。所发现的13种未知磷酸化蛋白为揭示CagA的致病机制提供了线索。     

幽门螺杆菌不同基因型和基因亚型与甲硝唑耐药性的研究

目的研究Helicobacter pylori菌株本身的毒力差异是否与H.pylori菌株对甲硝唑的敏感性有关。方法 用E-test方法检测109株H.pylori菌株对甲硝唑的敏感性;PCR检测H.pylori菌株不同的vacA基因亚型、cagA、iceA和babA2基因型。结果 云南地区甲硝唑耐药率为67.89％;vacA、cagA、iceAl、babA2基因的各种基因亚型和基因型在H.pylori菌株甲硝唑耐药率上无显著性差异。结论 H.pylori菌株本身的毒力差异与H.pylori菌株对甲硝唑的敏感性无关。     

中国辽宁地区人群幽门螺杆菌感染菌株与相关性胃疾病的关系

目的:探讨中国辽宁地区人群H pylori致病基因的疾病相关性,为揭示H pylori的致病机制及监测H pylori相关性胃疾病的高危人群提供线索.方法:选取胃黏膜活检标本491例,分组浅表性胃炎(GS)、萎缩性胃炎(GA)、溃疡(GU)、胃癌(GC),在微需氧的条件下,培养出H pylori 222例,并用标准的酚-氯仿方法提取菌种DNA后经聚合酶链反应及琼脂糖凝胶电泳对cagA,vacA,iceA基因亚型进行检测.同时取胃窦、体、角黏膜各1块,经石蜡切片,HE染色,行组织病理学诊断.结果:GA组感染m2(43.1%)亚型菌株构成比最高,与GU(18.2%)和GC(17.9%)组相比差异有统计学意义(P=0.015,P=0.020),与GS(30.00%)组相比差异没有统计学意义(P= 0.084).在GA组中,感染s1m2亚型菌株有22例(44.9%),与本组病例中其他基因亚型相比差别均有统计学意义,与Gu、GC组感染s1m2亚型菌株相比差别有统计学意义(P=0.039),与GS组相比差别没有统计学意义(P=0.067).结论:中国辽宁地区人群感染s1m2型菌株与萎缩性胃炎发生有关.     

幽门螺杆菌对AGS细胞蛋白激酶C同工酶表达的影响

目的研究PKC同工酶在H.pylori感染引起胃癌发生中起作用。方法将幽门螺杆菌和人胃上皮腺癌细胞系AGS细胞共培养（细菌∶细胞=200∶1）,在幽门螺杆菌攻击AGS细胞后的0h、0.5h、1h、4h、6h、12h、24h时间点分别提取AGS细胞的总RNA,同时提取相对应时间点平行培养的未受幽门螺杆菌攻击的AGS细胞的总RNA作为对照组,以Beta-actin为内参照,应用Taq-Man实时荧光定量RT-PCR技术研究这些样品的PKC同工酶的mRNA变化情况。结果与对照组相比,PKCε、PKCγ、PKCι、PKCζ、PKCα mRNA水平呈现增高趋势;PKCθ mRNA水平呈现持续下降趋势;PKCδ mRNA水平与对照组呈现一致表达趋势。结论H.pylori可能通过上调具有肿瘤增殖活性的PKCα、ε、γ、ι、ζ,下调了具有凋亡活性的PKCθ,参与H.pylori引起胃癌的发生过程。H.pylori对PKCδ mRNA水平没有影响。     

Effect of physiological concentrations of vitamin C on gastric cancer cells and Helicobacter pylori

BACKGROUND: Gastric juice vitamin C may be protective against gastric carcinogenesis but concentrations are significantly reduced by Helicobacter pylori infection. We investigated the in vitro effects of vitamin C at concentrations comparable with those found in gastric juice on gastric cancer cells and H pylori. METHODS: Gastric cancer cell lines and various H pylori strains were treated with L-ascorbic acid for up to 72 hours. Cell viability, and protein and DNA synthesis were determined. Flow cytometry was used for assessment of H pylori adherence, cell cycle distribution, and apoptosis. H pylori growth and its haemagglutination activity were determined using viability count and microtitration assay. RESULTS: Vitamin C induced a significant dose dependent growth inhibition of gastric AGS and MKN45 cells but this effect was significantly reduced at levels similar to those in gastric juice of H pylori infected patients (<50 microM). Although vitamin C had no obvious effect on H pylori growth, haemagglutination activity, or adherence ability to gastric AGS cells compared with untreated controls, it significantly enhanced H pylori associated apoptosis and induced cell cycle arrest in these cells. CONCLUSION: Vitamin C may inhibit gastric cancer cell growth and alter H pylori induced cell cycle events at concentrations comparable with those in gastric juice, but has no effect on H pylori growth or pathogenicity. However, the inhibitory effect on gastric cancer cells was lost at vitamin C concentrations found in patients with H pylori infection.     

Transactivation of the EGFR by AP-1 is induced by Helicobacter pylori in gastric cancer

BACKGROUND: Helicobacter pylori infection of the gastric mucosa is strongly associated with gastritis, peptic ulcer disease, and gastric cancer. However, the mechanisms by which H. pylori causes cancer are currently unknown. Binding of epidermal growth factor (EGF) to its receptor (EGFR) may be important in the development of gastric cancer. This interaction accelerates cell proliferation and migration, and triggers epithelial cell signaling. In this study, we investigated the effects of H. pylori on EGFR- and AP-1-mediated signal transduction pathways in the AGS gastric epithelial cell line and gastric tissue from humans. METHODS: Cells were treated with H. pylori and cell death was examined at a variety of time points using cell viability and trypan blue exclusion dye assay. To investigate the effects on EGFR regulation, AGS cells were transfected with a full-length and truncated EGFR luciferase (luc) reporter. Tissue microarray containing 44 samples of gastric biopsies from H. pylori-positive patients was analyzed for protein expression level of EGFR by immunohistochemistry. RESULTS: EGFR promoter activity was increased (twofold) 3 h after treatment with H. pylori commenced. Using a series of EGFR promoter deletion mutants, we identified a region that was crucial for transactivation of the EGFR by H. pylori. To determine whether AP-1 binding was altered, we transfected AGS cells with an AP-1 luciferase construct and then treated them with H. pylori for up to 6 h. We found that AP-1 activity was induced by H. pylori in gastric cells, while electrophoretic mobility shift assays confirmed that binding of AP-1 to the EGFR promoter site was increased following H. pylori treatment. Binding of c-Jun and c-Fos to the EGFR promoter region -1,062/-900 was induced eight- and six fold, respectively, using ChIP assay. Active EGFR staining was markedly increased in gastric mucosa from infected persons, compared to uninfected controls. CONCLUSIONS: We conclude that exposure of gastric cells to H. pylori induces increased production of EGFR through various signal transduction pathways, including those mediated by the EGFR and AP-1. Distinct effects on EGFR activation may specify the subset of AP-1 target genes that are selected, including those involved in proliferation and apoptosis. This is consistent with EGFR activation that was found in the gastric mucosa of humans infected with H. pylori. Hence, the balance between apoptosis and proliferation in these cells may be altered in response to injury caused by H. pylori infection, leading to an increased risk of cancer.     

Distinct gene expression profiles in gastric epithelial cells induced by different clinical isolates of Helicobacter pylori--implication of bacteria and host interaction in gastric carcinogenesis

BACKGROUND/AIMS: Helicobacter pylori (H. pylori) infection is a major risk factor of peptic ulcer, gastric cancer, and gastric mucosa-associated lymphoid tissue (MALT) lymphoma. The interplay between H. pylori and host is an important issue for elucidation of pathogenesis of H. pylori-related diseases. We aimed to examine simultaneously dynamic changes of multiple molecular pathways of infection affected by different H. pylori strains by cDNA microarrays. METHODOLOGY: To elucidate the cross-talk between H. pylori and gastric epithelial cells, we isolated three different H. pylori strains from patients with gastric cancer (GC), duodenal ulcer (DU), and gastric MALT lymphoma (MA). The bacteria were co-cultured with gastric epithelial cells (AGS) and total RNAs were extracted from AGS cells and used for detection of genes represented in the microarray. RESULTS: Of the 12,814 clones on the microarray, there were 522 genes expressed differently in the three groups. Of the 522 genes, there were 4 genes, 4 genes and 13 genes, either up- or down-regulated more than twofold change, in AGS cells induced specifically by GC, MA, and DU strain, respectively. The GC and DU strains induced more genes involving in carcinogenesis, such as pim-1, jun B, and VEGF. CONCLUSIONS: Our data by cDNA microarray suggest bacterial factors may determine the outcomes of H. pylori infection. The expression profiles of cDNA microarray provide clues for diagnosis, treatment, and prevention of H. pylori-related gastroduodenal diseases.     

慢性胃炎胃黏膜细胞DNA含量和增殖活性的流式细胞仪检测

背景慢性萎缩性胃炎是一种胃癌癌前状态,研究表明正常胃黏膜、癌前病变和胃癌细胞的DNA含量随病变的进展而逐渐增高。目的应用流式细胞仪检测慢性胃炎胃黏膜细胞的DNA含量和增殖活性,探讨两者在慢性胃炎发生、发展过程中的临床意义。方法选取90例经胃镜检查诊断为慢性胃炎者的胃黏膜活检标本,制备单细胞悬液,应用流式细胞仪进行细胞DNA含量和增殖活性检测。结果所有慢性胃炎胃黏膜细胞的DNA倍体类型均为二倍体,但慢性萎缩性胃炎和慢性萎缩性胃炎伴肠化生胃黏膜细胞的增殖指数(PI)较慢性非萎缩性胃炎显著增高(P<0.05)。除慢性非萎缩性胃炎外,其余慢性胃炎组幽门螺杆菌(H.pylori)阳性患者胃黏膜细胞的PI值均较阴性患者显著增高(P<0.05)。结论慢性萎缩性胃炎和H.pylori阳性慢性胃炎胃黏膜细胞的增殖活性显著增高。应用流式细胞仪检测胃黏膜细胞的DNA含量和增殖活性,也许能成为胃癌癌前状态和癌前病变病理诊断的参考指标。     

Potential therapeutic significance of increased expression of aryl hydrocarbon receptor in human gastric cancer

AIM： To determine the functional significance of aryl hydrocarbon receptor （AhR） in gastric carcinogenesis, and to explore the possible role of AhR in gastric cancer （GC） treatment. METHODS： RT-PCR, real-time PCR, and Western blotting were performed to detect AhR expression in 39 GC tissues and five GC cell lines. AhR protein was detected by immunohistochemistry （IHC） in 290 samples： 30 chronic superficial gastritis （CSG）, 30 chronic atrophic gastritis （CAG）, 30 intestinal metapiasia （IN）, 30 atypical hyperplasia （AH）, and 70 GC. The AhR agonist tetrachlorodibenzo-para-dioxin （TCDD） was used to treat AGS cells. MTr assay and flow cytometric analysis were performed to measure the viability, cell cycle and apoptosis of AGS cells.RESULTS： AhR expression was significantly increased in GC tissues and GC cell lines. IHC results indicated that the levels of AhR expression gradually increased, with the lowest levels in CSG, followed by CAG, IM, AH and GC. AhR expression and nuclear translocation were significantly higher in GC than in precancerous tissues. TCDD inhibited proliferation of AGS cells via induction of growth arrest at the G1-S phase. CONCLUSION： AhR plays an important role in gastric carcinogenesis. AhR may be a potential therapeutic target for GC treatment.     

Effects of Helicobacter pylori on proliferation of gastric epithelial cells in vitro

OBJECTIVE: H. pylori infection of the gastric mucosa has been associated with an increase in gastric epithelial cell proliferation. However, in vitro adherence of H. pylori to gastric epithelial cells is associated with reduced cell proliferation. Reduction of epithelial cell proliferation may contribute to ulcer formation and delay ulcer healing. The following study was undertaken to elucidate the ability of cagA-positive and -negative strains to impede gastric epithelial cell proliferation. METHODS: A human gastric adenocarcinoma cell line (AGS) was overlaid with either cagA-positive or cagA-negative H. pylori strains suspended in cell culture medium. Proliferation of AGS cells was analyzed by performing direct cell counts and by measuring metabolism of a soluble tetrazolium compound (MTS), after exposure to H. pylori for 24 h. RESULTS: When compared with control cells cultured in medium alone, AGS cell proliferation was reduced by 45.6% and 28.5% due to exposure to cagA-negative and cagA-positive strains, respectively. When bacterial-induced cytotoxicity was assessed by measuring release of lactose dehydrogenase (LDH) into the culture medium, cagA-positive strains were shown to induce significantly more cytotoxicity than cagA-negative strains. CONCLUSIONS: These experiments demonstrate that H. pylori exposure to AGS cells significantly reduces cell proliferation. However, cagA-positive strains that induce more cell injury reduce cell proliferation to a lesser extent than cagA-negative strains. Persistent replication of gastric epithelial cells injured by exposure to cagA-positive strains may be partially responsible for the stronger association with gastric cancer in persons infected with cagA-positive H. pylori strains.     

幽门螺杆菌CagA C-端功能域特征及其生物学功能研究

目的　克隆源自临床分离的幽门螺杆菌 (Hp)菌株CagADNA序列 ,比较其C 端氨基酸序列与国外菌株的差异 ,并分析其磷酸化能力和转染胃上皮细胞后的生物学功能。方法　从 39株临床分离的HpDNA基因组中用PCR方法扩增cagAC 端DNA ,经琼脂糖凝胶电泳后割胶回收DNA片段进行测序。分别构建cagA的原核细胞和真核细胞表达载体并进行CagAC 端氨基酸磷酸化能力测定。 结果　有 38株菌株检测到CagADNA片段 ,CagA阳性率为 97.4 % (38/ 39)。测序后发现 ,克隆的 38株阳性菌株CagA蛋白均仅含 1个重复序列和 2～ 4个串联的谷氨酸 脯氨酸 异亮氨酸 酪氨酸 丙氨酸(EPIYA)序列 ,且在重复序列的D2区氨基酸序列均为天冬氨酸 苯丙氨酸 天冬氨酸 (DFD)。来自胃癌和非胃癌患者的CagA蛋白串联的EPIYA序列数目差异无显著性。用原核细胞表达的CagA蛋白进行体外磷酸化试验 ,重复序列中的酪氨酸能被磷酸化 ,其余的在EPIYA中的酪氨酸也能被磷酸化 ,但转染的AGS细胞株中仅重复序列中的酪氨酸能被磷酸化。在转染AGS细胞株后少数细胞 (<10 % )因骨架重构而出现典型的“蜂鸟”样改变 ,与直接用Hp感染AGS细胞时类似 ,且对转染的AGS细胞再用Hp感染后 ,其“蜂鸟”样细胞的百分比也无明显增加。结论　源自国人的HpCagA蛋白结构不同于欧美国家     

Phenotypic and genotypic characterization of Helicobacter pylori from patients with and without peptic ulcer disease

BACKGROUND: Helicobacter pylori plays an important role in peptic ulcer disease, although not all H. pylori-infected persons will develop a peptic ulcer. Currently, H. pylori strains cannot be divided into commensals and pathogens. METHODS: Fifty H. pylori strains were cultured from patients divided into five groups on the basis of upper endoscopic findings: gastric ulcer, duodenal ulcer, gastritis, esophagitis, or normal. The ultrastructural adherence pattern in vivo, autoagglutination, hemagglutination, adhesion to human gastric adenocarcinoma (AGS) cells, and the lipopolysaccharide (LPS) profile of H. pylori strains were recorded; randomly amplified polymorphic DNA (RAPD) and urease gene typing were performed and correlated with diagnostic groups. RESULTS: Electron micrographs showed that H. pylori strains from patients with gastric ulcers adhered more frequently through filamentous strands and were less frequently found free in mucus than any other diagnostic group (P < 0.0001). Neither median hemagglutination titer nor median adhesion capacity to a human gastric adenocarcinoma cell line was related to endoscopic findings. Nevertheless, H. pylori strains from patients with gastric ulcers were more prone to autoagglutinate than were strains from the other diagnostic groups (P = 0.03). H. pylori strains from gastric ulcer patients were found to be more homogeneous, as determined by RAPD and urease gene typing, than strains from the other diagnostic groups (P < 0.01). In addition, a positive correlation was found between a patient's age and the adhesion to AGS cells of the patient's H. pylori strain (P = 0.006). CONCLUSION: A combination of an H. pylori autoagglutination test, RAPD, and urease gene typing may be useful in separating gastric ulcer-related strains from duodenal ulcer-related and non-ulcer dyspepsia-related strains.