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>

Viability of sprout seeds as affected by treatment with aqueous chlorine dioxide and dry heat, and reduction of Escherichia coli O157:H7 and Salmonella enterica on pak choi seeds by sequential treatment with chlorine dioxide, drying, and dry heat

Choi, S.,Beuchat, L.R.,Kim, H.,Ryu, J.H. Academic Press 2016 FOOD MICROBIOLOGY Vol.54 No.-

<P>Germination rates of 11 types of sprout seeds (alfalfa, broccoli, kohlrabi, kyona, mustard, pak choi, red kohlrabi, red radish, red young radish, tatsoi, and violet radish) treated with ClO2 (200 mg/ml, 5 min) or dry-heat (80 degrees C/23% relative humidity [RH], 24 h) were determined. Pak choi, red radish, and tatsoi seeds showed highest tolerance to both ClO2 and dry-heat treatments. Next, pak choi seeds were inoculated with Escherichia coli O157:H7 (5.4 log CFU/g) or Salmonella enterica (4.8 log CFU/g) and sequentially treated with ClO2 (200 mg/ml, 5 min), drying (45 degrees C/23% RH, 24 h), and dry heat (80 degrees C/23% RH, 48 h). E. coli O157:H7 was inactivated, but S. enterica was not eliminated (>3.8 log CFU/g reduction). Pak choi seeds inoculated with the pathogens were treated with ClO2, drying, and dry heat and subsequently sprouted for 5 days. When seeds were not completely decontaminated, initial populations of E. coli O157:H7 and S. enterica on seeds (<1.0 log CFU/g) increased to >5.3 and >8.4 log CFU/g of sprouts, respectively. This study shows that sequential treatments of pak choi seeds with ClO2, drying, and dry heat are effective in reducing large numbers of E. coli O157:H7 and S. enterica without loss of seed viability. (C) 2015 Elsevier Ltd. All rights reserved.</P>

국내 분리 일본뇌염 바이러스 유전자에 대한 항체생성 연구(Ⅰ) : cloning of JEV viral genes

박찬,최우영,이호동,채수림,신은진,김인범,표재환,박근용,조해월 국립보건연구원 1999 국립보건원보 Vol.36 No.-

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>

Effects of DME mixing on number density and size properties of soot particles in counterflow non-premixed ethylene flames

최재혁,B. C. Choi,S. M. Lee,S. H. CHUNG,K. S. Jung,W. L. Jeong,S. K. Choi,S. K. Park 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.5

In order to investigate the effect of DME mixing on the number density and size of soot particles, DME was mixed in a counter flownon-premixed ethylene flame with mixture ratios of 5%, 14% and 30%. A laser extinction/scattering technique has been adopted tomeasure the volume fraction, number density, and mean size of soot particles. The experimental results showed that the highest soot concentrationswere observed for flames with mixture ratios of 5% and 14%; however, for a mixture ratio of 30% the soot concentrationdecreased. Numerical results showed that the concentrations of propargyl radicals (C3H3) at the 5% and 14% ratios were higher thanthose measured in the ethylene-based flame, and the production of benzene (C6H6) in the 5% and 14% DME mixture flames was alsoincreased. This indicates the crucial role of propargyl in benzene ring formation. These reactions generally become stronger with increasedDME mixing, except for A1 + H2 → A1 + H (-R554) and n-C4H5 + C2H2 → A1 + H (R542). Therefore, it is indicated that addingDME to ethylene flames promotes benzene ring formation. Note that although the maximum C6H6 concentration is largest in the 30%DME mixing flame, the soot volume fraction is smaller than those for the 5% and 14% mixture ratios. This is because the local C6H6concentration decreases in the relatively low temperature region in the fuel side where soot growth occurs.

Effects of Addition Level and Chemical Type of Propionate Precursors in Dicarboxylic Acid Pathway on Fermentation Characteristics and Methane Production by Rumen Microbes In vitro

Li, X.Z.,Yan, C.G.,Choi, S.H.,Long, R.J.,Jin, G.L.,Song, Man K. Asian Australasian Association of Animal Productio 2009 Animal Bioscience Vol.22 No.1

Two in vitro experiments were conducted to examine the effects of propionate precursors in the dicarboxylic acid pathway on ruminal fermentatation characteristics, $CH_4$ production and degradation of feed by rumen microbes. Fumarate or malate as sodium salts (Exp. 1) or acid type (Exp. 2) were added to the culture solution (150 ml, 50% strained rumen fluid and 50% artificial saliva) to achieve final concentrations of 0, 8, 16 and 24 mM, and incubated anaerobically for 0, 1, 3, 6, 9 and 12 h at $39^{\circ}C$. For both experiments, two grams of feed consisting of 70% concentrate and 30% ground alfalfa (DM basis) were prepared in a nylon bag, and were placed in a bottle containing the culture solution. Addition of fumarate or malate in both sodium salt and acid form increased (p<0.0001) pH of culture solution at 3, 6, 9 and 12 h incubations. The pH (p<0.0001) and total volatile fatty acids (VFA, p<0.05) were enhanced by these precursors as sodium salt at 3, 6 and 9 h incubations, and pH (p<0.001) and total VFA (p<0.01) from fumarate or malate in acid form were enhanced at a late stage of fermentation (9 h and 12 h) as the addition level increased. pH was higher (p<0.001) for fumarate than for malate as sodium salt at 3 h and 6 h incubations. Propionate ($C_3$) proportion was increased (p<0.0001) but those of $C_2$ (p<0.05) and $C_4$ (p<0.01 - p<0.001) were reduced by the addition of sodium salt precursors from 3 h to 12 incubation times while both precursors in acid form enhanced (p<0.011 - p<0.0001) proportion of $C_3$ from 6h but reduced (p<0.018 - p<0.0005) $C_4$ proportion at incubation times of 1, 3, 9 and 12 h. Proportion of $C_3$ was increased (p<0.05 - p<0.0001) at all incubation times by both precursors as sodium salt while that of $C_3$ was increased (p<0.001) from 6h but $C_4$ proportion was decreased by both precursors in acid form as the addition level increased. Proportion of $C_3$ was higher (p<0.01 - p<0.001) for fumarate than malate as sodium salt from 6 h incubation but was higher for malate than fumarate in acid form at 9 h (p<0.05) and 12 h (p<0.01) incubation times. Increased levels (16 and 24 mM) of fumarate or malate as sodium salt (p<0.017) and both precursors in acid form (p<0.028) increased the total gas production, but no differences were found between precursors in both chemical types. Propionate precursors in both chemical types clearly reduced (p<0.0001 - p<0.0002) $CH_4$ production, and the reduction (p<0.001 - p<0.0001) was dose dependent as the addition level of precursors increased. The $CH_4$ generated was smaller (p<0.01 - p<0.0001) for fumarate than for malate in both chemical types. Addition of fumarate or malate as sodium type reduced (p<0.004) dry matter degradation while both precursors in both chemical types slightly increased neutral detergent fiber degradability of feed in the nylon bag.

Effects of the novel angiotensin II receptor type I antagonist, fimasartan on myocardial ischemia/reperfusion injury

Han, J.,Park, S.J.,Thu, V.T.,Lee, S.R.,Long, L.T.,Kim, H.K.,Kim, N.,Park, S.W.,Jeon, E.S.,Kim, E.J.,Yoon, C.H.,Cho, G.Y.,Choi, D.J. Elsevier/North-Holland Biomedical Press 2013 INTERNATIONAL JOURNAL OF CARDIOLOGY Vol.168 No.3

Background: The aim of this study was to investigate the cardioprotective effect of fimasartan, a newly developed angiotensin II receptor type I blocker (ARB), against myocardial ischemia/reperfusion (I/R) injury and to identify the mechanism by which it reduces mitochondrial damage. Methods: Fimasartan was administered intravenously to Sprague-Dawley rats (3mg/kg), cardiomyocytes (50μM), and H9c2 cells (50μM) before ischemia or hypoxia. Myocardial infarction (MI), echocardiograms, DNA fragmentation, terminal deoxynucleotidyl transferase-mediated dUTP in situ nick-end labeling, immunoblotting, oxygen consumption, confocal microscopic appearance, and L-type Ca<SUP>2+</SUP> current (I<SUB>Ca,L</SUB>) were then assessed. Results: Fimasartan pretreatment remarkably reduced the rate of MI and improved cardiac performance well after I/R (n=9/group). Fimasartan also reduced apoptotic cell death both in vivo and in hypoxia/reoxygenation (H/R)-treated H9c2 cells (n=5~8/group). H/R-induced mitochondrial O<SUB>2</SUB><SUP>-</SUP> production and collapse of membrane potential were markedly attenuated in fimasartan-treated cardiomyocytes (n=4~6/group). Additionally, mitochondrial Ca<SUP>2+</SUP> overload during reoxygenation was suppressed by fimasartan (n=4~6/group), and this was found to be possibly related to the inhibition of I<SUB>Ca,L</SUB> and mitochondrial Ca<SUP>2+</SUP> uniporter. Furthermore, fimasartan pretreatment increased phosphorylations of Akt and glycogen synthase kinase-3β (n=5~7/group), decreased pro-apoptotic p53 levels, and increased anti-apoptotic Bcl-2 levels (n=4) during reperfusion. Conclusions: Fimasartan preconditioning has the potential to modulate Bcl-2 and suppress I/R-induced Ca<SUP>2+</SUP> overload by inhibiting I<SUB>Ca,L</SUB> and MCU. These beneficial effects could prevent the mitochondrial dysfunction and apoptosis accompanied by I/R.

Metal-semiconductor double shell hollow nanocubes for highly stable hydrogen generation photocatalysts

Choi, W.,Park, G.,Bae, K. L.,Choi, J.,Nam, K.,Song, H. Royal Society of Chemistry 2016 Journal of Materials Chemistry A Vol.4 No.35

<P>Noble metal-CdS double shell hollow nanocubes were synthesized by sequential four-step nanoscale reactions, including galvanic replacement, sulfidation, cationic exchange, and reduction. The photocatalytic H-2 generation using these hollow nanocubes indicated significant competition between electron transfer and electron-hole recombination, and showed remarkable stability against photocorrosion.</P>

MSV로 변이시킨 가토신장세포의 배양조건에 따른 지방조성변화에 대한 연구

최한용,박주홍,김화영,김영래,이인수,조영준,박재윤,차종희,고광삼 朝鮮大學校 附設 醫學硏究所 1987 The Medical Journal of Chosun University Vol.12 No.1

Differencies of lipid composition of murine sarcoma virus 97017 transformed rabbit kidney cells and their plasma membranes in monolayer and suspension culture were studied. Free cholesterol was the major neutral lipid extracted from the whole cells and plasma membranes of all these cultures. Triglyceride increased about 6 to 50 folds in suspension grown whole cells and their plasma membranes compared to those from monolayer cultures. The μ mole of total neutral lipids and phospholipids are elevated in plasma membranes compared to whole cells from monolayer cultures bur arc similar in suspension cultures. The distribution of fatty acids in the major lipid classes of plasma membranes and whole cells generally follow the composition of calf serumused in the culture media.

Inhalable self-assembled albumin nanoparticles for treating drug-resistant lung cancer

Choi, S.H.,Byeon, H.J.,Choi, J.S.,Thao, L.,Kim, I.,Lee, E.S.,Shin, B.S.,Lee, K.C.,Youn, Y.S. Elsevier Science Publishers 2015 Journal of controlled release Vol.197 No.-

Direct pulmonary delivery of anti-cancer agents is viewed as an effective way of treating lung cancer. Here, we fabricated inhalable nanoparticles made of human serum albumin (HSA) conjugated with doxorubicin and octyl aldehyde and adsorbed with apoptotic TRAIL protein (TRAIL/Dox HSA-NP). The octyl aldehyde and doxorubicin endowed HSA with significant hydrophobicity that facilitated self-assembly. TRAIL/Dox HSA-NP was found to have excellent particle size (~340nm), morphology, dispersability, and aerosolization properties. TRAIL/Dox HSA-NP displayed synergistic cytotoxicity and apoptotic activity in H226 lung cancer cells vs. HSA-NP containing TRAIL or Dox alone. TRAIL/Dox HSA-NP was well deposited in the mouse lungs using an aerosolizer, and TRAIL and Dox-HSA were found to be gradually released over 3days. The anti-tumor efficacy of pulmonary administered TRAIL/Dox HSA-NP was evaluated in BALB/c nu/nu mice bearing H226 cell-induced metastatic tumors. It was found that the tumors of H226-implanted mice treated with TRAIL/Dox HSA-NP were remarkably smaller and lighter than those of mice treated with TRAIL or Dox HSA-NP alone (337.5+/-7.5; 678.2+/-51.5; and 598.9+/-24.8mg, respectively). Importantly, this improved anti-tumor efficacy was found to be due to the synergistic apoptotic effects of Dox and TRAIL. In the authors' opinion, TRAIL/Dox HSA-NP offers a potential inhalable anti-lung cancer drug delivery system. Furthermore, the synergism displayed by combined use of Dox and TRAIL could be used to markedly reduce doxorubicin doses and minimize its side effects.