Gyung-Hyuck Ko

Proteomic Analysis of the Sarcosine-Insoluble Outer Membrane Fraction of Helicobacter pylori Strain 26695

Helicobacter pylori causes gastroduodenal disease, which is mediated in part by its outer membrane proteins (OMPs). To identify OMPs of H. pylori strain 26695, we performed a proteomic analysis. A sarcosine-insoluble outer membrane fraction was resolved by two-dimensional electrophoresis with immobilized pH gradient strips. Most of the protein spots, with molecular masses of 10 to 100 kDa, were visible on the gel in the alkaline pI regions (6.0 to 10.0). The proteome of the OMPs was analyzed by matrix-assisted laser desorption ionization-time-of-flight mass spectrometry. Of the 80 protein spots processed, 62 spots were identified; they represented 35 genes, including 16 kinds of OMP. Moreover, we identified 9 immunoreactive proteins by immunoblot analysis. This study contributes to the characterization of the H. pylori strain 26695 proteome and may help to further elucidate the biological function of H. pylori OMPs and the pathogenesis of H. pylori infection.

Identifying the major proteome components of Helicobacter pylori strain 26695.

The whole genome sequences of Helicobacter pylori strain 26695 have been reported. Whole cell proteins of H. pylori strain 26695 cells were obtained and analyzed by two‐dimensional electrophoresis, using immobilized pH gradient strips. The most abundant proteins were shown in the region of pI 4.0–9.5 with molecular masses from 10 to 100 kDa. Soluble proteins were precipitated by the use of 0–80% saturated solutions of ammonium sulfate. Soluble proteins precipitated by the 0–40% saturations of ammonium sulfate produced similar spot profiles and their abundant protein spots had acidic pI regions. However, a number of soluble proteins precipitated by more than 60% saturation of ammonium sulfate were placed in the alkaline pI regions, compared to those precipitated by 40% saturation. In addition, we have performed an extensive proteome analysis of the strain utilizing peptide MALDI‐TOF‐MS. Among the 345 protein spots processed, 175 proteins were identified. The identified spots represented 137 genes. One‐hundred and fifteen proteins were newly identified in this study, including DNA polymerase III β‐subunit. These results might provide guidance for the enrichment of H. pylori proteins and contribute to construct a master protein map of H. pylori.

Changes in the Age-Specific Prevalence of Hepatitis A Virus Antibodies: A 10-Year Cohort Study in Jinju, South Korea

The changing patterns in seroprevalence rates of hepatitis A virus antibodies among children and adolescents from 1988 to 1997 reflect the cohort effects that occurred over 10 years in South Korea. Our results suggest that the majority of adolescents and young adults are at risk of symptomatic hepatitis A virus infection and morbidity.

Comparison of Helicobacter pylori infection between Fukuoka, Japan and Chinju, Korea.

Helicobacter pylori is the causative agent of type B chronic gastritis, and plays a major role in the pathogenesis of gastroduodenal ulcer and gastric cancer. Because gastric cancer has been the leading cause of cancer mortality in Japan and Korea, we conducted a seroepidemiological study to estimate the prevalence of H. pylori infection in Japan and Korea in order to explain the current change in the gastric cancer incidences between two countries.

VEGF-C mediates RhoGDI2-induced gastric cancer cell metastasis and cisplatin resistance

Rho GDP dissociation inhibitor 2 (RhoGDI2) expression is correlated with tumor growth, metastasis and chemoresistance in gastric cancer. However, the mechanisms by which RhoGDI2 promotes tumor cell survival and metastasis remain unclear. In this study, we clearly demonstrate that RhoGDI2 upregulates VEGF‐C expression and RhoGDI2 expression is positively correlated with VEGF‐C expression in human gastric tumor tissues as well as parental gastric cancer cell lines. VEGF‐C depletion suppressed RhoGDI2‐induced gastric cancer metastasis and sensitized RhoGDI2‐overexpressing cells to cisplatin‐induced apoptosis in vitro and in vivo. Secreted VEGF‐C enhanced gastric cancer cell invasion and conferred cisplatin resistance to RhoGDI2‐overexpressing cells. We also show that RhoGDI2 positively regulates Rac1 activity in gastric cancer cells. Inhibition of Rac1 expression suppressed RhoGDI2‐induced VEGF‐C expression, and this inhibition was associated with decreased invasiveness and increased sensitivity to cisplatin in RhoGDI2‐overexpressing cells. Our results indicate that RhoGDI2 might be a potential therapeutic target for simultaneously reducing metastasis risk and enhancing chemotherapy efficacy in gastric cancer.

Changing pattern of antibiotic resistance of Helicobacter pylori in children during 20 years in Jinju, South Korea

The antimicrobial resistance capability of Helicobacter pylori is one of the critical factors in the failure to treat this pathogen. The purpose of this study was to investigate the changing pattern of primary antibiotic resistance rates in children in the southern central part of South Korea from 1990 to 2009.

Myositis Ossificans of the Abdominal Rectus Muscle: Report of a Case

We herein report a rare case of myositis ossificans originating from the abdominal rectus muscle, found in a 38-year-old woman who presented with a left upper abdominal mass. The mass was initially suspected to be a malignant neoplasm because no history of either operation or trauma existed for this patient. Moreover, the location of the mass was unusual and the enhancement patterns of the dynamic magnetic resonance images were similar to that of a malignant tumor. Based on the radiologic findings, a surgical exploration was performed. A well-circumscribed mass, which measured 3.2 × 2 cm, was found in the rectus muscle. Microscopic findings showed a typical zonal pattern with a fibroblastic central zone and a zone of ossification at the periphery. Although abdominal myositis ossificans is extremely rare, it is one of the causes of abdominal mass lesions and can be mistaken for a malignant tumor. Therefore, a thorough knowledge of the evolution of myositis ossificans is necessary and in cases with malignant suggestion on magnetic resonance imaging, like that seen in our case, we suggest that a surgical excision may be necessary for both the diagnosis and treatment.

Influencing Factors to Results of the Urease Test: Age, Sampling Site, Histopathologic Findings, and Density of Helicobacter pylori.

Purpose We investigated the positivity rate and the time period to the positive color change of the urease test in children and adults and assessed the correlation of the urease test to histopathologic findings. Methods From 1995 to 2000, endoscopic biopsies of the antrum and body were collected from 811 children and 224 adults and subjected to urease tests and histopathology. Results The positivity rate of the urease test was 49.4% for 0-4 years, 48.4% for 5-9 years, 47.3% for 10-15 years, and 62.5% for 20-29 years in the antrum. The positivity rate was 85.1% in 0-4 years, 82.3% in 5-9 years, 74.7% in 10-15 years, and 74.1% in 20-29 years for the body. In the antrum, the highest positivity rate was <1 hour for the group aged 10-29 years and 6-24 hours in the group <10 years old (p<0.0001). In the body, the highest positivity rate was <1 hour in adults and 6-24 hours in children (p<0.0001). The proportions of the positive reactions within 1 hour were similar for the antrum and the body. In the cases of more severe chronic gastritis, active gastritis, and Helicobacter pylori infiltration, a positive urease test reaction occurred more quickly (p<0.0001). Conclusion There were significant differences in urease tests according to age and sampling site. The discrepancy between the antrum and the body was greater in younger children. These results might be related to the low density and patchy distribution of bacteria in children and in the body.

pHP489, a Helicobacter pylori small cryptic plasmid, harbors a novel gene coding for a replication initiation protein.

We have analyzed a Helicobacter pylori plasmid, pHP489. The 1222-bp nucleotide sequence had one open reading frame, a DnaA-binding site, one direct repeat, and three inverted repeats. The (G+C) content of pHP489 was 33.3%. Although the nucleic acid sequence and deduced amino acid sequence were homologous to those of other bacterial plasmid Rep proteins, the degree of similarity was very low. A deletion analysis showed that the Rep protein was not required for the replication of pHP489 in its H. pylori host, but the host replication machinery was needed.

Characterization of a small cryptic plasmid, pHP51, from a Korean isolate of strain 51 of Helicobacter pylori.

The nucleotide sequence of a 3955-bp Helicobacter pylori plasmid, pHP51 was determined, and two open reading frames, ORF1 and ORF2, were identified. The deduced amino acid sequence of ORF1 was highly conserved (87-89%) among plasmid replication initiation proteins, RepBs. The function of ORF2 was not assigned because it lacked known functional domains or sequence similarity with other known proteins, although it had a HPFXXGNG motif that was also found in the cAMP-induced filamentation (fic) gene. Three kinds of repeats were present on the plasmid outside of the ORFs, including the R1 and R2 repeats that are common in H. pylori plasmids. One 100-bp sequence detected in the noncoding region of pHP51 was highly similar to the genomic sequence of H. pylori 26695.