Cloning, expression and characterization of recombinant CagA protein of Helicobacter pylori using monoclonal antibodies: Its potential in diagnostics.

Helicobacter pylori CagA protein plays an important role in the severity of the gastric diseases. Our aims were to clone the cagA 5'- conserved region of the gene, characterize the recombinant CagA (rCagA) protein by monoclonal antibodies (mAbs) and to use this protein for the detection of anti-CagA antibodies by an ELISA test. Our developed rCagA protein (67 kDa) showed an amino acid sequence homology of 83% and 80% with Western and East Asian type strains respectively. Two anti-rCagA (BS-53, CK-02) mAbs and 2 additional rCagA proteins of smaller sizes (60 kDa, 28 kDa) were developed for epitope determination. The BS-53 mAb recognized all 3 rCagA proteins while CK-02 mAb recognized only 2 of them indicating recognition of different epitopes. An in-house indirect ELISA using rCagA was developed to detect anti-CagA antibodies in sera of 59 patients. The ELISA results obtained when compared to those of the PCR gave a sensitivity, specificity and accuracy of 81%, 100% and 88% respectively. We have developed for the first time: a rCagA protein that showed high sequence homology with both Western and East Asian type strains and an indirect ELISA of high performance which can be used to detect anti-CagA antibodies in sera of infected patients worldwide.

A study on the effect of Helicobacter pylori infection on p53 expression in gastric cancer and gastritis tissues.

INTRODUCTION: Helicobacter pylori cause damage to gastric epithelial cells and alterations in the p53 gene that lead to cancer development. This study aimed to determine the correlation of p53 expression with H. pylori using immunohistochemistry, RFLP-PCR, and histopathology. METHODOLOGY: Gastric biopsy samples from gastric cancer (GC) (n = 54) and gastritis (n = 31) patients were examined for histopathological changes and expression of p53 protein by immunohistochemistry. RESULTS: Immunohistochemical analysis of p53 protein expression in H. pylori-positive GC sections showed an average of 44.3% positive cells in tumors and 6.9% in normal tissues, as compared to 16.4% and 4.4% in H. pylori-negative sections. P53 expression showed significant association with H. pylori (P = 0.005), invasion depth (P = 0.029) and inflammation reaction (P = 0.008). In gastritis sections, no difference in the average p53 staining in H. pylori-positive or -negative sections was seen. PCR-RFLP results also showed no difference in genotype frequencies of p53 in H. pylori-positive or -negative gastritis sections. Histopathology study of H. pylori-positive GC sections showed that 97.2% were the intestinal type and 2.8% the diffuse type, while in H. pylori-negative sections 35.2% were the intestinal type and 64.8% the diffuse type. Biopsy sections from H. pylori-positive gastritis patients revealed more severe inflammation than those of H. pylori-negative patients. CONCLUSION: Our results show that H. pylori infection affects p53 expression in GC. The average p53 expression was significantly higher in tumor than in normal tissues. In gastritis sections p53 expression was significantly associated with H. pylori.

H pylori infection and other risk factors associated with peptic ulcers in Turkish patients: a retrospective study.

AIM: To identify and evaluate the relative impact of H pylori infection and other risk factors on the occurrence of gastric ulcer (GU), duodenal ulcer (DU) and gastritis in Turkish patients. METHODS: A total of 4471 patients (48.3% female) out of 4863 attended the Samatya hospital in Istanbul (June 1999-October 2003) were included. The records of H pylori status (CLO-test), endoscopic findings of GU, DU and gastritis, personal habits (smoking, alcohol intake) and medication [non-steroidal anti-inflammatory drugs (NSAIDs), aspirin intake] were analyzed using multi-way frequency analysis. RESULTS: We have found that GU in the presence of H pylori had significant association with aspirin (P=0.0001), alcohol (P=0.0090) and NSAIDs (P=0.0372). DU on the other hand had significant association with aspirin/smoking/NSAIDs (P=0.0259), aspirin/alcohol (P=0.0002) and aspirin/smoking (P=0.0233), also in the presence of H pylori. In the absence of H pylori GU had significant association with alcohol/NSAIDs (P=0.0431), and NSAIDs (P=0.0436). While DU in the absence of H pylori had significant association with smoking/alcohol/ NSAIDs (P=0.0013), aspirin/NSAIDs (P=0.0334), aspirin/alcohol (P=0.0360). CONCLUSION: In the presence of H pylori, aspirin, alcohol and NSAIDs intake act as an independent risk factors that had an augmenting impact on the occurrence of GU and only together on the occurrence of DU in Turkish patients.

Canonical correlation analysis of factors involved in the occurrence of peptic ulcers.

The impact of risk factors on the development of peptic ulcers has been shown to vary among different populations. We sought to establish a correlation between these factors and their involvement in the occurrence of peptic ulcers for which a canonical correlation analysis was applied. We included 7,014 patient records (48.6% women, 18.4% duodenal ulcer [DU], 4.6% gastric ulcer [GU]) of those underwent upper gastroendoscopy for the last 5 years. The variables measured are endoscopic findings (DU, GU, antral gastritis, erosive gastritis, pangastritis, pyloric deformity, bulbar deformity, bleeding, atrophy, Barret esophagus and gastric polyp) and risk factors (age, gender, Helicobacter pylori infection, smoking, alcohol, and nonsteroidal anti-inflammatory drugs [NSAIDs] and aspirin intake). We found that DU had significant positive correlation with bulbar deformity (P=2.6 x 10(-23)), pyloric deformity (P=2.6 x 10(-23)), gender (P=2.6 x 10(-23)), H. pylori (P=1.4 x 10(-15)), bleeding (P=6.9 x 10(-15)), smoking (P=1.4 x 10(-7)), aspirin use (P=1.1 x 10(-4)), alcohol intake (P=7.7 x 10(-4)), and NSAIDs (P=.01). GU had a significantly positive correlation with pyloric deformity (P=1,6 x 10(-15)), age (P=2.6 x 10(-14)), bleeding (P=3.7 x 10(-8)), gender (P=1.3 x 10(-7)), aspirin use (P=1.1 x 10(-6)), bulbar deformity (P=7.4 x 10(-4)), alcohol intake (P=.03), smoking (P=.04), and Barret esophagus (P=.03). The level of significance was much higher in some variables with DU than with GU and the correlations with GU in spite of being highly significant the majority, were small in magnitude. In conclusion, Turkish patients with the following endoscopic findings bulbar deformity and pyloric deformity are high-risk patients for peptic ulcers with the risk of the occurrence of DU being higher than that of GU. Factors such as H. pylori, smoking, alcohol use, and NSAIDs use (listed in a decreasing manner) are risk factors that have significant impact on the occurrence of DU; aspirin has a significant impact on both DU and GU.