Epidemiology of Legionella and Climatic Variables in Seoul, Korea

Legionella species are abundant in the built environment and are increasingly recognized as a cause of Legionnaires' disease (LD). As the number of cases of Legionnaires' disease acquired by local communities in the Seoul metropolitan area in Korea has been increased, there was concern that changes in environmental factors could affect disease outbreaks. We described the association between climatic variables and occurrence of legionellosis in Korea and Legionella detection rate in Seoul area. A total of 418 cases of legionellosis were reported between 2014 and 2017. There was a seasonal peak in summer. LD continuously occurred from early spring to winter every year and rapidly increased in summer. In the regression analysis, the primary variables of interest- PM2.5 (µg/m³), NO₂ (ppb), and a number of the date of issue O₃ warning were not significant except for average temperature (R²=0.8075). The Legionella detection rate in Seoul, Korea showed a trend similar to precipitation (P=0.708, ANOVA). A relatively high proportion of Legionella detection rate was shown, especially cooling tower (17.7%) and public bath (19.3%). This finding is in line with current understanding of the ecological profile of this pathogen and supports the assertion that legionellosis occurs through contamination of water sources.

Molecular Characterization of Enterotoxigenic Escherichia coli in Foodborne Outbreak

Diarrheagenic Escherichia coli (E. coli) is a main cause of diarrhea worldwide. This study reports the investigation on the occurrence of enterotoxigenic E. coli (ETEC) serotype O27:H7-associated foodborne gastrointestinal disease that occurred at two schools, one middle school and one high school, in Seoul, Korea in June 2015. The immediate government investigation in 1,216 students and 19 food handlers in these two schools revealed that 116 students, 32 students in the middle school and 84 students in the high school, and 2 food handlers, one from middle school and the other from high school, developed gastrointestinal illness symptoms including diarrhea. Following lab investigation identified 29 ETEC serotype O27:H7 strains, 27 from 116 students and 2 from 19 food handlers. Pattern of pulsed-field gel electrophoresis analysis of ETEC isolates suggested that ETEC serotype O27:H7 caused the diarrheal outbreak in June 2015 in Seoul, Korea was a specific clone. In addition, these ETEC serotype O27:H7 isolates were highly resistance to the several antibiotics. The results from the present study provide the evidence that ETEC serotype O27:H7 can be an important cause of domestic foodborne outbreak in Korea.

Mutations in gyrA and parC Genes and Plasmid-Mediated Quinolone Resistance in Non-typhoid Salmonella Isolated from Pediatric Patients with Diarrhea in Seoul

A total of 91 non-typhoid Salmonella isolated from pediatric patients with diarrhea in Seoul from 2003 to 2009 was tested for antimicrobial susceptibility of nalidixic acid (NA). Forty strains of NA resistance or intermediate susceptible non-typhoid Salmonella were identified and their minimum inhibitory concentrations (MICs) of NA, ciprofloxacin (CIP), and norfloxacin (NOR) were determined. Of the 40 isolates, 26 were resistant to NA (MIC >256 microg/ml). Only one isolate was high-level resistant to CIP (12 microg/ml) and NOR (48 microg/ml). Mutations in gyrA and parC genes were studied by PCR and sequencing. All NA-resistant isolates carried point mutations in the gyrA quinolone resistance determining regions (QRDR) at codon 83 or 87 (MICs of NA, >256 microg/ml; MICs of CIP, 0.047~0.25 microg/ml; MICs of NOR, 0.38~1.5 microg/ml). A double change in GyrA was found in one Salmonella Enteritidis (MIC of CIP, 12 microg/ml; MIC of NOR, 48 microg/ml). In respect of the ParC protein, a single change at Thr57-->Ser was found in 3 isolates (MICs of NA, >256 microg/ml; MICs of CIP, 0.19~0.25 microg/ml; MICs of NOR, 1 microg/ml). At the same time, these strains changed from Ser83 to Tyr in the gyrA. The result of the investigation for the prevalence of plasmid-mediated quinolone resistance (PMQR) genes, 14 isolates harbored qnr gene among 40 isolates. All of 14 isolates showed decreased susceptibility at NA (MICs 4~16 microg/ml) and except one strain, all of qnr genes were identified as qnrB. Mutations in the gyrA gene and production of PMQR determinants were critical for quinolone resistance and decreased susceptibility to fluoroquinolone in these isolates.

Molecular Epidemiology of Legionella pneumophila Isolated from Bath Facilities of Public Establishments in Seoul

The genus Legionella is common in aquatic environments. Some species of Legionella are recognized as potential opportunistic pathogens for human, notably Legionella pneumophila that causes Legionellosis. During the summer season between June and August in 2010, we isolated 61 L. pneumophila from the bath facilities of public establishments of 25 wards in Seoul. The existence of 16S rRNA and mip gene of L. pneumophila was confirmed in the genome of the isolated strains by PCR. Among the 61 strains of L. pneumophila, thirty three isolates belong to serogroup 1 (54.1%), 13 isolates were serogroup 6 (21.3%), 9 isolates were serogroup 5 (14.8%), 3 isolates were serogroup 3 (4.9%), and 3 isolates were identified in serogroup 2 (4.9%). On pulsed-field gel electrophoresis (PFGE) analysis using SfiI, genetic types of L. pneumophila were classified into 8 (A to H) patterns by the band similarity with excess of 65%. Our results suggest the existence of serological and genetic diversity among the L. pneumophila isolates.

Expression of Hepatitis B Virus X Protein in Hepatocytes Suppresses CD8+ T Cell Activity

BACKGROUND: CD8+ T cells contribute to the clearance of Hepatitis B virus (HBV) infection and an insufficient CD8+ T cell response may be one of the major factors leading to chronic HBV infection. Since the HBx antigen of HBV can up-regulate cellular expression of several immunomodulatory molecules, we hypothesized that HBx expression in hepatocytes might affect CD8+ T cell activity. METHODS: We analyzed the activation and apoptosis of CD8+ T cells co-cultured with primary hepatocytes rendered capable of expressing HBx by recombinant baculovirus infection. RESULTS: Expression of HBx in hepatocytes induced low production of interferon-gamma and apoptosis of CD8+ T cells, with no effect on CD8 T cell proliferation. However, transcriptional levels of H-2K, ICAM-1 and PD-1 ligand did not correlate with HBx expression in hepatocytes. CONCLUSION: Our results suggest that HBx may inhibit CD8+ T cell response by regulation of interferon-gamma production and apoptosis.

Intracellular Antibody Fragment Against Hepatitis B Virus X Protein Does Not Inhibit Viral Replication

Replication of the hepatitis B virus is suppressed by deficiency of the X protein. Although several molecules that block cellular targets of X protein reduce the production of hepatitis B virus progeny, the effect of a specific inhibitor of X protein on viral replication has not been investigated. To block X protein specifically, we adopted an intracellular expression approach using H7 single chain variable fragment (H7scFv), an antibody fragment against X protein. We previously demonstrated that cytoplasmic expression of H7scFv inhibits X protein-induced tumorigenicity and transactivation. In this study, intracellular H7scFv expression inhibits reporter gene transactivation but not viral replication determined by endogenous hepatitis B virus polymerase activity assay and real-time PCR. Our findings imply that intracellular expression of antibody fragment against X protein may not be an alternative therapeutic modality for inhibition of hepatitis B virus replication.

Expression of Hepatitis C Virus Core Protein in Hepatocytes Does Not Modulate Proliferation or Apoptosis of CD8+ T Cells

Hepatocytes are the primary targets of the hepatitis C virus (HCV). While immunosuppressive roles of HCV core protein have been found in several studies, it remains uncertain whether core protein expressed in hepatocytes rather than in immune cells affects the CD8+ T cell response. In order to transduce genes selectively into hepatocytes, we developed a baculoviral vector system that enabled primary hepatocytes to express a target epitope for CD8+ T cells, derived from ovalbumin (OVA), with or without HCV core protein. Culture of OVA-specific CD8+ T cells with hepatocytes infected with these baculoviral vectors revealed that core protein has no effect on proliferation or apoptosis of CD8+ T cells. Our results suggest that HCV core protein does not exert its suppressive role on the CD8+ T cell immune response through expression in hepatocytes.

Expression of Intracellular Single Chain Antibody Specific to Hepatitis B Virus X Protein

BACKGROUND: Intracellular antibody specific to hepatitis B virus X protein (HBx) might be useful for studying the role of HBx in hepatocellular carcinogenesis and HBV replication. METHODS: With variable region genes for H7 monoclonal anti-HBx Ab, we constructed a vector for bacterial expression of single chain Ab (scFv) and a vector for eukaryotic cell expression of it. The expression of H7 scFv and its binding activity against HBx was examined by immunoblotting and immunofluorescence microscopy. RESULTS: H7 scFv expressed in bacterial cells retained reactivity to HBx. We demonstrated its intracytoplasmic expression in CosM6 eukaryotic cells. CONCLUSION: This is the first study showing the expression of intracellular anti-HBx Ab in eukaryotic cells. H7 scFv may be a good tool to study the function of HBx in HBV infection

A Comparative Study on Dietary Habits and Dietary Attitudes among Middle School Students with Different Obesity Indexes / 대한지역사회영양학회지

The object of this study was done to assert the dietary habits, food intake, and dietary attitudes of 332 middle school students in a small city. The subject were divided into doe groups based on weight length index (WLI). Anthropometric data showed that the mean height and weight were 169.5 +/-8.2 cm and 55.1 +/-11.5 kg in the male students and 158.9 +/-5.9 cm and 48.1 +/-7.6 kg in the female students. The mean WLIs for male and female students were 103.0 +/-19.7 and 96.3 +/-12.8, respectively. Of the male students 27.9% and of the female students 32.1% were underweight, and of the male students 28.9% and of the female students 13.0% were overweight based on WLI index. Lack of good dietary habits in the overweight group tended to be the highest, the normal group was the second highest, and the underweight group was the lowest. The regularity of eating breakfast and flood prejudice scores in the overweight group were significantly higher than those in the normal and underweight group. With respect to flood intake, the normal group tended to consume grains, yellow or green vegetables, vegetables with light color, fruits, milk, yogurt, cheese\`, seaweeds, fat-floods, instant floods, sweet floods, carbonated drinks, and spicy and salty floods more frequently. The underweight group tended to consume meat-ham, eggs, fish and fried, stir-fried flood more frequently In dietary attitudes, the overweight group tended to have more favorable dietary attitudes, and the normal group tended to have negative dietary attitudes. The underweight group showed more negative responses to trying to eat/drink milk, yogurt, or cheese everyday than the overweight groups. It might be suggested that more effective nutritional programs should be developed and implemented to ensure good dietary habits in middle school students, including the overweight, as well as the underweight group. Further research on the comparison of dietary characteristics is needed, with consideration of the subjects' WLI.

Smad6 Gene and Suppression of Radiation-Induced Apoptosis by Genistein in K562 cells / 대한방사선종양학회지

PURPOSE: The genes involved on the suppression of radiation-induced apoptosis by genistein in K562 leukemia cell line was investigated. MATERIALS AND METHODS: K562 cells in exponential growth phase were irradiated with a linear accelerator at room temperature. Forx-ray irradiation and drug treatment, cultures were prepared at 2x105 cells/mL. The cells were irradiated with 10 Gy (Clinac 1800C, Varian, USA). Stock solutions of herbimycin A (HMA, Calbiochem, UK) and genistein (Calbiochem, UK) were prepared in dimethylsulfoxide (DMSO, Sigma, UK). After incubation at 37degreesC for 24 h, PCR-select cDNA subtractive hybridization, dot hybridization, DNA sequencing and Northern hybridization were examined. RESULTS: Smad6 gene was identified from the differentially expressed genes in K562 cells incubated with genistein which had been selected by PCR-select cDNA subtractive hybridization. The mRNA expression of Smad6 in K562 cells incubated with genistein was also higher than control group by Northern hybridization analysis. CONCLUSION: We have shown that Smad6 involved on the suppression of radiation-induced apoptosis by genistein in K562 leukemia cell line. It is plausible that the relationship between Smad6 and the suppression of radiation-induced apoptosis is essential for treatment development based on molecular targeting designed to modify radiation-induced apoptosis.

Teat Shock Response Ingibits IFN-gamma Plus LPS - Induced NO Synthase Expression in Murine Peritoneal Macrophages / 대한면역학회지

No abstract available.