Sanitizing radish seeds by simultaneous treatments with gaseous chlorine dioxide, high relative humidity, and mild heat

Bang, J.,Choi, M.,Son, H.,Beuchat, L.R.,Kim, Y.,Kim, H.,Ryu, J.H. Elsevier Science Publishers 2016 International journal of food microbiology Vol.237 No.-

<P>Sanitizing radish seeds intended for edible sprout production was achieved by applying simultaneous treatments with gaseous chlorine dioxide (ClO2), high relative humidity (RH, 100%), and mild heat (55 degrees C). Gaseous ClO2 was produced from aqueous ClO2 (0.66 ml) by mixing sulfuric acid (5% w/v) with sodium chlorite (10 mg/mL) in a sealed container (1.8 L). Greater amounts of gaseous ClO2 were measured at 23% RH (144 ppm after 6 h) than at 100% RH (66 ppm after 6 h); however, the lethal activity of gaseous ClO2 against naturally occurring mesophilic aerobic bacteria (MAB) on radish seeds was significantly enhanced at 100% RH. For example, when exposed to gaseous ClO2 at 23% RH, the number of MAB on radish seeds decreased from 3.7 log CFU/g to 2.6 log CFU/g after 6 h. However, when exposed to gaseous ClO2 at 100% RH for 6 h, the MAB population decreased to 0.7 log CFU/g after 6 h. Gaseous ClO2 was produced in higher amounts at 55 degrees C than at 25 degrees C, but decreased more rapidly over time at 55 degrees C than at 25 degrees C. The lethal activity of gaseous ClO2 against MAB on radish seeds was greater at 55 degrees C than at 25 degrees C. When radish seeds were treated with gaseous ClO2 (peak concentration: 195 ppm) at 100% RH and 55 degrees C, MAB were reduced to populations below the detectable level (<-0.7 log CFU/g) within 2 h without decreasing the seed germination rate (97.7%). The lethality of combined treatments against artificially inoculated Escherichia coli O157:H7 was also evaluated. When exposed to gaseous ClO2 at 100% RH and 55 degrees C for 6 h, the initial number of E. coli O157:H7 (3.5 log CFU/g) on radish seeds decreased to below the detection limit (0.7 log CFU/g) by direct plating but it was not eliminated from seeds. The germination rate of radish seeds was not significantly (P> 0.05) decreased after treatment for 6 h. The information reported here will be useful when developing decontamination strategies for producing microbiologically safe radish seed sprouts. (C) 2016 Published by Elsevier B.V.</P>

Coumarins reduce biofilm formation and the virulence of Escherichia coli O157:H7

Lee, J.H.,Kim, Y.G.,Cho, H.S.,Ryu, S.Y.,Cho, M.H.,Lee, J. G. Fischer 2014 Phytomedicine Vol.21 No.8

E. coli O157:H7 is the most common cause of hemorrhagic colitis, and no effective therapy exists for E. coli O157:H7 infection. Biofilm formation is closely related to E. coli O157:H7 infection and constitutes a mechanism of antimicrobial resistance. Hence, the antibiofilm or antivirulence approach provides an alternative to antibiotic strategies. Coumarin and its derivatives have a broad range of biological effects, and in this study, the antibiofilm activities of nine coumarins were investigated against E. coli O157:H7. Coumarin or umbelliferone at 50μg/ml was found to inhibit biofilm E. coli O157:H7 formation by more than 80% without affecting bacterial growth. Transcriptional analysis showed that coumarins repressed curli genes and motility genes in E. coli O157:H7, and these findings were in-line with observed reductions in fimbriae production, swarming motility, and biofilm formation. In addition, esculetin repressed Shiga-like toxin gene stx2 in E. coli O157:H7 and attenuated its virulence in vivo in the nematode Caenorhabditis elegans. These findings show that coumarins have potential use in antivirulence strategies against persistent E. coli O157:H7 infection.

Combined effects of chlorine dioxide, drying, and dry heat treatments in inactivating microorganisms on radish seeds

Bang, J.,Kim, H.,Kim, H.,Beuchat, L.R.,Ryu, J.H. Academic Press 2011 FOOD MICROBIOLOGY Vol.28 No.1

We determined the combined effectiveness of ClO<SUB>2</SUB> (200 and 500 μg/ml, 5 min), air drying [25 <SUP>o</SUP>C, 40% relative humidity (RH), 2 h], and mild dry heat (55 <SUP>o</SUP>C, 23% RH, up to 48 h) treatments in killing total aerobic bacteria (TAB), Escherichia coli O157:H7, and molds and yeasts (MY) on radish seeds. A 5.1-log reduction in the number of TAB was achieved on radish seeds treated with 200 or 500 μg/ml ClO<SUB>2</SUB> followed by air drying for 2 h and dry heat treatment for 48 h or 24 h, respectively. When radish seeds were treated with 200 and 500 μg/ml ClO<SUB>2</SUB>, air dried, and heat treated for 12 h and 6 h, respectively, the initial population of E. coli O157:H7 (5.6 log CFU/g) on seeds was reduced to an undetectable level (<0.8 log CFU/g). However, the pathogen was detected in 5-day-old sprouts. The reduction of MY (1.2-1.0 log CFU/g) on radish seeds under similar experimental conditions was not changed significantly during subsequent heat treatment up to 48 h. Results show that treating radish seeds with 500 μg/ml ClO<SUB>2</SUB>, followed by air dried at 25 <SUP>o</SUP>C for 2 h and heat treatment at 55 <SUP>o</SUP>C for 36 h achieved a >5-log CFU/g reduction of TAB and E. coli O157:H7. These observations will be useful when developing effective strategies and practices to enhance the microbiological safety of radish sprouts.

Survival and colonization of <i>Escherichia coli</i> O157:H7 on spinach leaves as affected by inoculum level and carrier, temperature and relative humidity

Choi, S.,Bang, J.,Kim, H.,Beuchat, L.R.,Ryu, J.‐,H Blackwell Publishing Ltd 2011 Journal of applied microbiology Vol.111 No.6

<P><B>Abstract</B></P><P><B>Aims: </B> To determine survival and colonization of <I>Escherichia coli</I> O157:H7 on spinach leaves as affected by inoculum level and carrier, temperature and relative humidity (r.h.).</P><P><B>Methods and Results: </B> Spinach leaves were inoculated with suspensions of <I>E.?coli</I> O157:H7 in distilled water (DW) and 0·1% peptone water (PW) and incubated at 4, 12 and 25°C and 43, 85 and 100% r.h. The number of <I>E.?coli</I> O157:H7 on leaves (5·6 or 1·9 log CFU per leaf) inoculated using DW as a carrier medium increased significantly at 25°C and 100% r.h. within 120 h but remained constant or decreased significantly under other test conditions. <I>E.?coli</I> O157:H7 on leaves (5·4 log CFU per leaf) inoculated using PW as a carrier increased significantly within 72 and 24 h, respectively, at 12 or 25°C and 100% r.h.; counts using a low inoculum (2·2 log CFU per leaf) increased significantly within 24 h at 25°C.</P><P><B>Conclusions: </B> <I>Escherichia coli</I> O157:H7 can colonize on spinach leaves at 12 or 25°C in a 100% r.h. environment. Organic matter in the inoculum carrier may provide protection and nutrients which enhance survival and colonization.</P><P><B>Significance and Impact of the Study: </B> Colonization of <I>E.?coli</I> O157:H7 on spinach leaves as affected by organic matter in the inoculum, temperature and r.h. was determined. These observations will be useful when developing strategies to prevent growth of <I>E.?coli</I> O157:H7 on pre‐ and postharvest spinach.</P>

유착에 의한 AGS 및 Hep-G2 세포 표면 구조의 변화

박동규 ( D. K. Park ),전훈재 ( H. J. Chun ),박재홍 ( J. H. Park ),박철희 ( C. H. Park ),진윤태 ( Y. T. Jeen ),이홍식 ( H. S. Lee ),이상우 ( S. W. Lee ),엄순호 ( S. H. Um ),최재현 ( J. H. Choi ),김창덕 ( C. D. Kim ),류호상 ( H. S. Ryu 대한소화기학회 2002 대한소화기학회 춘계학술대회 Vol.2002 No.-

<목적> 최근 H. pylori 유착에 의한 세포 표면 구조의 변화에 관한 연구가 시도되어지고 있으나 actin 의 변화여부 및 그 특성에 관해서는 아직 명확히 정립되지 못한 실정이다. Rho GTPase는 세포 표면의 미세돌기인 microvilli, filopodia 및 membrane ruffle의 형성과 관련이 있으며, 최근 AGS 세포에서 H. pylori가 Rac activation에 의하여 membrane ruffle을 형성한다는 것과 Rac

Pathogenesis of Enterohemorrhagic <i>Escherichia coli</i> O157:H7 is mediated by the cytochrome P450 family in <i>Caenorhabditis elegans</i> animal model

Ryu, S.,Oh, S.,Park, M.R.,Lee, W.J.,Yun, B.,Choi, H.J.,Oh, M.H.,Oh, N.S.,Song, M.H.,Kim, Y. BUTTERWORTH-HEINEMANN 2019 FOOD CONTROL Vol.103 No.-

<P><B>Abstract</B></P> <P>Foodborne pathogens, including enterohemorrhagic <I>Escherichia coli</I> (EHEC) O157:H7, may enter from the farm environment and foods via several different vectors and influence human health. Here, we employed <I>Caenorhabditis elegans</I> as a host model system and compared specific host responses during EHEC O157:H7 infection using whole-transcriptome analysis. To elucidate the immune pathways stimulated by EHEC O157:H7, we employed quantitative real-time polymerase chain reaction (qRT-PCR), transgenic worms, and RNAi. Whole-transcriptome analysis revealed that genes encoding the cytochrome P450 (CYP450) family were induced more than 10-fold during EHEC O157:H7 infection in <I>C. elegans</I> host models. Importantly, <I>C. elegans</I> mutants lacking CYP450 genes were highly susceptible to EHEC O157:H7 infection compared with wild-type N2 worms. Consistent with susceptibility tests, qRT-PCR results indicated that CYP450 loss-of-function mutations significantly affected the transcriptional induction of antimicrobial peptide genes, such as <I>clec-60</I>. Together, our results provide critical insights into host strategies for avoiding EHEC O157:H7 pathogenesis in the gastrointestinal tract via the cytochrome P450 family and highlights potential molecular targets for preventing the virulence of EHEC O157:H7 in foods.</P>

An electric powertrain modelling of a full cell hybrid electric vehicle and development of a power distribution algorithm using H_[unknown] control

Ryu, J.-H.,Lee, H.-J.,Sunwoo, M.-H. Professional Engineering Publishing 2010 Proceedings of the Institution of Mechanical Engin Vol.224 No.8

<P>This paper presents an electric powertrain model of a parallel-type fuel cell hybrid electric vehicle (FCHEV) and its robust H-infinity controller for efficient power distribution between a fuel cell and a battery. The electric powertrain of the parallel-type FCHEV is composed of a fuel cell stack system, a d.c.-to-d.c. converter, and a battery. The fuel cell stack system is connected to the battery through the d.c.-to-d.c. converter, which is a key component for power distribution between the fuel cell and the battery. In this study, the electric powertrain model of the FCHEV was derived from the dynamic differential equations of the equivalent-circuit model that describes the electric powertrain. Using this model, the robust H-infinity controller was designed to control the power distribution between the fuel cell and the battery efficiently. Finally, the results of driving-cycle simulation verified the performance of the proposed robust H-infinity controller.</P>

Dipeptidyl petidase-IV inhibitor (gemigliptin) inhibits tunicamycin-induced endoplasmic reticulum stress, apoptosis and inflammation in H9c2 cardiomyocytes

Hwang, H.J.,Jung, T.W.,Ryu, J.Y.,Hong, H.C.,Choi, H.Y.,Seo, J.A.,Kim, S.G.,Kim, N.H.,Choi, K.M.,Choi, D.S.,Baik, S.H.,Yoo, H.J. North-Holland 2014 Molecular and cellular endocrinology Vol.392 No.1

The direct effects of dipeptidyl peptidase-IV (DPP-IV) inhibitors on endoplasmic reticulum (ER) stress-induced apoptosis and inflammation in cardiomyocytes have not been elucidated. H9c2 cell viability, which was reduced by tunicamycin, was increased after DPP-IV inhibitor gemigliptin treatment. Gemigliptin significantly decreased the tunicamycin-mediated increase in glucose regulated protein 78 (GRP78) expression and ER stress-mediated signaling molecules such as protein kinase RNA-like endoplasmic reticulum kinase (PERK)/C-EBP homologous protein (CHOP) and inositol-requiring enzyme 1α (IRE1α)/c-Jun N-terminal kinase (JNK)-p38. Furthermore, gemigliptin effectively induced Akt phosphorylation in a dose-dependent manner. Using flow cytometry and Hoechst staining, we showed that treatment with Akt inhibitor significantly blocked the anti-apoptotic effects mediated by gemigliptin. The reduction in tunicamycin-induced GRP78 level and PERK/CHOP pathway activity by gemigliptin was reversed after treatment with Akt inhibitor. In conclusion, gemigliptin effectively inhibited ER stress-induced apoptosis and inflammation in cardiomyocytes via Akt/PERK/CHOP and IRE1α/JNK-p38 pathways, suggesting its direct protective role in cardiovascular diseases.

동적 상황 기반 응용 개발 플랫폼의 설계 및 구현

송호근(H.K song),서주홍(J.H Seo),최정희(J.H. Choi),신승중(S.J. Shin),류대현(D.H. Ryu),나종화(J.H. Na) 한국정보과학회 2004 한국정보과학회 학술발표논문집 Vol.31 No.2Ⅲ

유비쿼터스 컴퓨팅의 응용분야에서 거시적이고 동적인 개념을 쉽게 구현할 수 있는 플랫폼을 설계하고 구현 하였다. 주위 정보를 수집하는 센서들과 이 정보들을 서버에게 보내는 PDA 그리고 여러 지역을 감지하기 위해 이동이 가능하게 하는 이동체 등으로 구성되어 있다. 응용하는 곳에 따라 이동체, 센서, 룰셋 등을 변경할 수 있도록 플랫폼을 설계하였다. 이 논문에서는 이 플랫폼의 H/W의 구성과 S/W의 구성을 살펴보고 이를 응용한 곳에 대해 설명한다. 그리고 향후 개발 방향에 대해 언급한 후 끝을 맺는다.

Exendin-4 induction of cyclin D1 expression in INS-1 beta-cells: involvement of cAMP-responsive element.

Kim, M-J,Kang, J-H,Park, Y G,Ryu, G R,Ko, S H,Jeong, I-K,Koh, K-H,Rhie, D-J,Yoon, S H,Hahn, S J,Kim, M-S,Jo, Y-H Journal of Endocrinology, Ltd. [etc.] 2006 The Journal of endocrinology Vol.188 No.3

<P>Glucagon-like peptide-1 (GLP-1) and its analog exendin-4 (EX) have been considered as a growth factor implicated in pancreatic islet mass increase and beta-cell proliferation. This study aimed to investigate the effect of EX on cyclin D1 expression, a key regulator of the cell cycle, in the pancreatic beta-cell line INS-1. We demonstrated that EX significantly increased cyclin D1 mRNA and subsequently its protein levels. Although EX induced phosphorylation of Raf-1 and extracellular-signal-regulated kinase (ERK), both PD98059 and exogenous ERK1 had no effect on the cyclin D1 induction by EX. Instead, the cAMP-elevating agent forskolin induced cyclin D1 expression remarkably and this response was inhibited by pretreatment with H-89, a protein kinase A (PKA) inhibitor. Promoter analyses revealed that the cAMP-responsive element (CRE) site (at position -48; 5'-TAACGTCA-3') of cyclin D1 gene was required for both basal and EX-induced activation of the cyclin D1 promoter, which was confirmed by site-directed mutagenesis study. For EX to activate the cyclin D1 promoter effectively, CRE-binding protein (CREB) should be phosphorylated and bound to the putative CRE site, according to the results of electrophoretic mobility shift and chromatin immunoprecipitation assays. Lastly, a transfection assay employing constitutively active or dominant-negative CREB expression plasmids clearly demonstrated that CREB was largely involved in both basal and EX-induced cyclin D1 promoter activities. Taken together, EX-induced cyclin D1 expression is largely dependent on the cAMP/PKA signaling pathway, and EX increases the level of phosphorylated CREB and more potently trans-activates cyclin D1 gene through binding of the CREB to the putative CRE site, implicating a potential mechanism underlying beta-cell proliferation by EX.</P>