Hee-Shang Youn

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.

Genome-Wide Association Study of Ulcerative Colitis in Koreans Suggests Extensive Overlapping of Genetic Susceptibility With Caucasians

Background:Recent genome-wide association studies and meta-analyses have identified 47 susceptibility loci for ulcerative colitis (UC) in Caucasian populations. A previous genome-wide association study of UC in a Japanese population suggested marginal sharing of susceptibility loci between Caucasian and Asian populations. We performed a genome-wide association studies to identify UC susceptibility loci in a Korean population and further comparative study. Methods:We analyzed 581,060 autosomal single-nucleotide polymorphisms (SNPs) in 388 individuals with UC and 739 control subjects in the discovery stage. For the validation, 64 suggestive SNPs were analyzed in an additional 417 affected individuals and 732 control subjects. Results:Three genetic loci were validated for significant association, and all were previously reported in Caucasians including the major histocompatibility complex region (top SNP, rs9271366; P = 1.03 × 10−18, odds ratio [OR] = 2.10), 16q24.1 (rs16940186; P = 4.39 × 10−10, OR = 1.56), and RNF186-OTUD3-PLA2G2E at chromosome arm 1p36.13 (top SNP, rs4654903 in OTUD3; P = 7.43 × 10−9, OR = 0.64). Although failed to reach genome-wide statistical significance, 2 additional loci previously reported in Caucasians including rs17085007 at chromosome arm 13q12 and JAK2 at chromosome arm 9p24 were significant after Bonferroni correction (Pcorrected = 0.0016 and Pcorrected = 0.0056, respectively). FOS, UBE2L3, the JAK2 gene region, and rs1297265 at chromosome arm 21q21.1 likely play a role in both Crohn’s disease and UC. Conclusions:Our data support the biologic significance of the overlapping loci for UC between Caucasian and Korean populations. Our data suggest that genetic associations for UC tend to overlap more extensively among different ethnic groups than those for Crohn’s disease, which shows well-established dependence on ethnicity.

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.

Quantitative analysis of representative proteome components and clustering of Helicobacter pylori clinical strains.

Background:  Several Helicobacter pylori proteins have been reported to be associated with severe symptoms of gastric disease. However, expression levels of most of these disease‐associated proteins require further evaluation in order to clarify their relationships with gastric disease patterns. Representative proteome components of 71 clinical isolates of H. pylori were analyzed quantitatively to determine whether the protein expression levels were associated with gastric diseases and to cluster clinical isolates.

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.

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.

Helicobacter pylori γ-glutamyltranspeptidase induces cell cycle arrest at the G1-S phase transition

In our previous study, we showed that Helicobacter pylori γ-glutamyltranspeptidase (GGT) is associated with H. pylori-induced apoptosis through a mitochondrial pathway. To better understand the role of GGT in apoptosis, we examined the effect of GGT on cell cycle regulation in AGS cells. To determine the effect of recombinant GGT (rGGT) on cell cycle distribution and apoptosis, rGGT-treated and untreated AGS cells were analyzed in parallel by flow cytometry using propidium iodide (PI). We found that rGGT inhibited the growth of AGS cells in a time-dependent manner, and that the pre-exposure of cells to a caspase-3 inhibitor (z-DEVD-fmk) effectively blocked GGT-induced apoptosis. Cell cycle analysis showed G1 phase arrest and apoptosis in AGS cells following rGGT treatment. The rGGT-mediated G1 phase arrest was found to be associated with down-regulation of cyclin E, cyclin A, Cdk 4, and Cdk 6, and the up-regulation of the cyclindependent kinase (Cdk) inhibitors p27 and p21. Our results suggest that H. pylori GGT induces cell cycle arrest at the G1-S phase transition.

Anthocyanins from black soybean inhibit Helicobacter pylori-induced inflammation in human gastric epithelial AGS cells.

Infection with Helicobacter pylori leads to gastritis, peptic ulcers and gastric cancer. Moreover, when the gastric mucosa is exposed to H. pylori, gastric mucosal inflammatory cytokine interleukin‐8 (Il‐8) and reactive oxygen species increase. Anthocyanins have anti‐oxidative, antibacterial and anti‐inflammatory properties. However, the effect of anthocyanins in H. pylori‐infected cells is not yet clear. In this study, therefore, the effect of anthocyanins on H. pylori‐infected human gastric epithelial cells was examined. AGS cells were pretreated with anthocyanins for 24 hrs followed by H. pylori 26695 infection for up to 24 hrs. Cell viability and ROS production were examined by 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide and 2′,7′–dichlorofluorescein diacetate assay, respectively. Western blot analyses and RT‐PCR were performed to assess gene and protein expression, respectively. IL‐8 secretion in AGS cells was measured by ELISA. It was found that anthocyanins decrease H. pylori‐induced ROS enhancement. Anthocyanins also inhibited phosphorylation of mitogen‐activated protein kinases, translocation of nuclear factor‐kappa B and Iκβα degradation. Furthermore anthocyanins inhibited H. pylori‐induced inducible nitric oxide synthases and cyclooxygenase‐2 mRNA expression and inhibited IL‐8 production by 45.8%. Based on the above findings, anthocyanins might have an anti‐inflammatory effect in H. pylori‐infected gastric epithelial cells.

Distinctive pattern of white matter injury in neonates with rotavirus infection

Objective: To report a consecutive series of neonates with seizures or apnea and displaying white matter injuries with distinctive magnetic resonance diffusion-weighted imaging (DWI) pattern, and to discuss the high positive rate of rotavirus infection seen in these patients. Methods: In a retrospective review of neonates who were admitted to a tertiary referral center with seizures or apnea, we found a distinctive pattern of white matter injury (symmetrical restricted diffusion in the periventricular white matter and white matter tracts including the corpus callosum) in 18 patients. We describe the clinical and laboratory features of these 18 neonates. Additional PCR analyses for rotaviruses and parechoviruses were performed on banked frozen samples of CSF of 4 patients and blood of 15 patients. Results: All 18 patients were born at term and healthy until symptoms occurred 4–7 days after birth. No history of asphyxia was observed. Only 1 patient presented with fever, and no patient showed a rash. All patients except 1 (94.4%) were rotavirus-positive in stool samples. However, neither rotaviruses nor enteroviruses/parechoviruses were detected in the CSF and blood. Tissue loss was observed in 5 of 8 subjects on repeat MRI scans. Conclusions: Neonates with this distinctive DWI pattern had a high positive rate of rotavirus infection, without evidence of other pathogens, and were characterized as term newborns with neurologic symptoms arising approximately the fifth day after birth. Although the specificity of this pattern is unclear, rotavirus testing should be considered for neonates presenting with this DWI pattern.