The role of periplasmic antioxidant enzymes (superoxide dismutase and thiol peroxidase) of the Shiga toxin-producing Escherichia coli O157:H7 in the formation of biofilms

Kim, Young Hoon,Lee, Yunho,Kim, Saehun,Yeom, Jinki,Yeom, Sujin,Seok Kim, Beom,Oh, Sangnam,Park, Sungsu,Jeon, Che Ok,Park, Woojun WILEY-VCH Verlag 2006 Proteomics Vol.6 No.23

<P>This study examined the role of the periplasmic oxidative defense proteins, copper, zinc superoxide dismutase (SodC), and thiol peroxidase (Tpx), from the Shiga toxin-producing Escherichia coli O157:H7 (STEC) in the formation of biofilms. Proteomic analyses have shown significantly higher expression levels of both periplasmic antioxidant systems (SodC and Tpx) in STEC cells grown under biofilm conditions than under planktonic conditions. An analysis of their growth phase-dependent gene expression indicated that a high level of the sodC expression occurred during the stationary phase and that the expression of the tpx gene was strongly induced only during the exponential growth phase. Exogenous hydrogen peroxide reduced the aerobic growth of the STEC sodC and tpx mutants by more than that of their parental strain. The two mutants also displayed significant reductions in their attachment to both biotic (HT-29 epithelial cell) and abiotic surfaces (polystyrene and polyvinyl chloride microplates) during static aerobic growth. However, the growth rates of both wild-type and mutants were similar under aerobic growth conditions. The formation of an STEC biofilm was only observed with the wild-type STEC cells in glass capillary tubes under continuous flow-culture conditions compared with the STEC sodC and tpx mutants. To the best of our knowledge, this is the first mutational study to show the contribution of sodC and tpx gene products to the formation of an E. coli O157:H7 biofilm. These results also suggest that these biofilms are physiologically heterogeneous and that oxidative stress defenses in both the exponential and stationary growth stages play important roles in the formation of STEC biofilms.</P>

POTENTIAL APPLICATION OF PREBIOTICS AND PROBIOTICS

Saehun Kim 한국식품영양과학회 2001 한국식품영양과학회 학술대회발표집 Vol.50 No.-

The importance of probiotics and prebiotics in health-promoting effect on the host is increasing. Recent studies on gastrointestinal system have contributed to further understanding of the mechanisms involved in the interaction between probiotics and prebiotics. In this presentation, the beneficial effects of probiotics and prebiotics, and applications of microencapsulation technique for the application of prebiotics and probiotics are described.

Induction of Serum Amyloid A Genes Is Associated with Growth and Apoptosis of HC11 Mammary Epithelial Cells

KHO, Yoonjung,KIM, Sungchan,YOON, Byung Sun,MOON, Jai-Hee,KIM, Bona,KWAK, Sungwook,WOO, Junghee,OH, Sejong,HONG, Kichang,KIM, Saehun,KIM, Hyunggee,YOU, Seungkwon,CHOI, Yunjaie Japan Society for Bioscience, Biotechnology, and A 2008 Bioscience, Biotechnology, and Biochemistry Vol.72 No.1

<P>In this study, we examined the expression and functions of serum amyloid A (SAA) isoforms during apoptosis of HC11 mammary gland epithelial cells. Expression of SAA mRNAs and apoptosis were increased in HC11 cells by serum withdrawal and gradually decreased upon the addition of serum, or epidermal growth factor (EGF). TNFα treatment of HC11 cells also induced expression of SAA genes, and the effect on SAA1 and SAA2 expression was suppressed by treatment with MG132, and in cells transfected with a dominant negative mutant form of IκBα. Similar results were observed in response to interleukin-1 (IL-1), IL-6 and interferon γ (IFNγ). Furthermore, overexpression of the SAA1 and SAA2 isoforms suppressed growth and accelerated apoptosis of HC11 cells by increasing caspase 3/7 and caspase 8 activities, but the apoptotic effect of tumor necrosis factor α (TNFα) on HC11 cells was not enhanced. We found that expression of <I>SAA1</I> and <I>SAA2</I>, but not <I>SAA3</I>, was regulated by an NFκB-dependent pathway, and that overexpression of SAA isoforms accelerated the apoptosis of HC11 cells.</P>

WDNM1 is associated with differentiation and apoptosis of mammary epithelial cells.

Kho, Yoonjung,Kim, Sungchan,Yoon, Byung Sun,Moon, Jai-Hee,Kwak, Sungwook,Park, Gyuman,Woo, Junghee,Oh, Sejong,Hong, Kichang,Kim, Saehun,Kim, Hyunggee,You, Seungkwon,Choi, Yunjaie Marcel Dekker 2008 Animal biotechnology Vol.19 No.2

<P>In this study, we show that expression of the Westmead DMBA8 nonmetastatic cDNA 1 (WDNM1) gene was increased upon SFM and/or TNFalpha treatment, with a corresponding increase in apoptotic cells, and gradually decreased following re-stimulation with serum in HC11 mammary epithelial cells. TNFalpha induced WDNM1 expression showed the NFkappaB-dependent mechanism since it's expression was abrogated in IkappaBalphaM (super-repressor of NFkappaB)-transfected cells, but not those transfected with control vector. Furthermore, overexpression of WDNM1 suppressed growth and differentiation, and accelerated apoptosis of HC11 cells. Thus, our results demonstrate that WDNM1 gene expression, regulated by the TNFalpha-NFkappaB signal pathway, is associated with HC11 cell apoptosis.</P>

근골격계질환 예방을 위한 딥러닝 기반 작업자의 근골격계부담 분석 시스템 개발

김가경(Gakyoung Kim),김수현(Soohyun Kim),김조경(Jogyeong Kim),조세훈(Saehun Jo),정기효(Kihyo Jung) 대한인간공학회 2021 대한인간공학회 학술대회논문집 Vol.2021 No.11

Objective: 본 연구는 근골격계질환 예방을 위해 작업 현장에서 촬영된 영상(또는 실시간 영상)에서 작업자의 근골격계 부담을 평가하는 시스템을 개발하였다. Background: 직업성 근골격계질환은 업무상 질병자의 약 60%를 차지할 정도로 심각한 수준이며, 그로 인해 산업안전보건법은 작업자의 근골격계에 부담을 주는 작업이 있을 경우 유해요인조사를 실시하도록 하고 있다. 그러나 유해요인조사에 포함된 정량적 인간공학평가는 평가자가 육안으로 작업 부하를 평가하기 때문에 시간이 많이 소요되고 평가자 간의 신뢰도가 상대적으로 낮은 것으로 보고되고 있다. Method: 본 연구는 작업 현장에서 촬영된 영상(CCTV, 웹캠, 또는 핸드폰)을 대상으로 반자동으로 정량적 인간공학 평가를 실시할 수 있는 시스템을 개발하였다. 인간공학적 평가는 OWAS를 기반으로 하였으며, OWAS 평가에 필요한 작업자의 동작 정보는 딥러닝을 통해 개발된 합성곱 신경망을 활용하여 획득되었다. 본 연구의 평가 시스템은 Matlab을 활용하여 구현되었으며, 개발된 시스템의 성능은 기존 연구에 비교 평가되었다. Results: 본 연구의 시스템은 실시간으로 촬영되는 영상에 대해 실시간으로 근골격계 부담을 정량적으로 분석할 수 있다. 또한, 본 연구의 시스템은 분석 보고서 기능이 있어 근골격계부담이 과도했던 동작과 그때의 근골격계부담 점수를 보고서(PDF)로 정리할 수 있다. 본 연구의 시스템에서 계산된 근골격계부담 점수는 기존 연구에 제시된 인간공학 전문가의 평가 결과와 유사성이 높은 것으로 분석되었다. Conclusion: 본 연구의 시스템은 작업 현장에서 촬영된 영상으로부터 작업자의 근골격부담을 OWAS를 활용하여 정량적으로 평가할 수 있는 것으로 나타났다. Application: 본 연구에서 개발된 시스템은 산업현장의 근골격계질환 예방을 위해 작업자의 근골격계 부담을 정량적으로 평가하는데 유용하게 활용될 수 있을 것으로 기대된다.

Physicochemical interactions of cycloamylose with phenolic compounds

Rho, Shin-Joung,Mun, Saehun,Hong, Jung Sun,Kim, Young-Lim,Do, Ha V.,Kim, Young-Wan,Han, Sang-Ik,Kim, Yong-Ro Applied Science Publishers 2017 Carbohydrate Polymers Vol.174 No.-

<P><B>Abstract</B></P> <P>The complex formation capability of cycloamylose (CA), having a degree of polymerization of 23–45, with phenolic compounds (PCs) was investigated using various physicochemical techniques. The fluorescence intensity of PCs increased and then reached a plateau at 10–20mM cyclodextrin, while it continued to increase at up to 60mM CA. Thermodynamic data of CA complexes with PCs revealed that the binding process was primarily enthalpy-driven and spontaneous. CA favored to form the most stable complex with chlorogenic acid (CHA) among all PCs. Chemical shift changes for the protons in interior and exterior of CA, as well as in PCs suggested a possible formation of both inclusion and extramolecular interactions between CA and PCs. The ROESY spectrum confirmed that the aromatic moieties of CHA were partially interacted with CA molecules through relatively weak binding. XRD, DSC, and SEM results also supported the complex formation by intermolecular interaction between CA and CHA.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Cycloamylose consisting of 23–45 glucoses produced using 4-α-glucanotransferase. </LI> <LI> Cycloamylose spontaneously formed a complex with phenolic compounds. </LI> <LI> Phenolic compounds interacted with both internal cavity and surface of cycloamylose. </LI> <LI> Cycloamylose was especially beneficial over cyclodextrin at high concentration. </LI> </UL> </P>

Photosensitizer-conjugated polymeric nanoparticles for redox-responsive fluorescence imaging and photodynamic therapy

Kim, Hyunjin,Mun, Saehun,Choi, Yongdoo The Royal Society of Chemistry 2013 Journal of Materials Chemistry B Vol.1 No.4

Influence of methylcellulose on attributes of β-carotene fortified starch-based filled hydrogels: Optical, rheological, structural, digestibility, and bioaccessibility properties

Mun, Saehun,Park, Shinjae,Kim, Yong-Ro,McClements, David Julian Elsevier 2016 Food Research International Vol.87 No.-

<P><B>Abstract</B></P> <P>There is considerable interest in controlling the gastrointestinal fate of nutraceuticals to improve their efficacy. In this study, the influence of methylcellulose (an indigestible polysaccharide) on lipid digestion and β-carotene bioaccessibility was determined. The carotenoids were encapsulated within lipid droplets that were then loaded into rice starch hydrogels containing different methylcellulose levels. Incorporation of 0 to 0.2% of methylcellulose had little impact on the dynamic shear rheology of the starch hydrogels, which may be important for formulating functional foods with desirable textural attributes. The microstructure, lipid digestion, and β-carotene bioaccessibility of the filled hydrogels were measured as the samples were passed through simulated oral, gastric, and small intestinal phases. The lipid digestion rate and carotenoid bioaccessibility decreased with increasing methylcellulose. This effect was attributed to the ability of the methylcellulose to inhibit molecular diffusion, promote droplet flocculation, or bind gastrointestinal components thereby inhibiting triacylglycerol hydrolysis at the lipid droplet surfaces. This information may be useful for rationally designing functional foods with improved nutritional benefits.</P> <P><B>Highlights</B></P> <P> <UL> <LI> β-Carotene-loaded oil droplets were encapsulated in starch-based hydrogels. </LI> <LI> The impact of methylcellulose on gastrointestinal fate of droplets was determined. </LI> <LI> Methylcellulose did not alter starch hydrogel rheology, but delayed lipid digestion. </LI> <LI> Carotenoid bioaccessibility was reduced at higher methylcellulose levels. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Confocal micrographs showing microstructural changes during passage through simulated oral, gastric, and intestinal phases; (A) emulsions; (B) filled starch hydrogels without methylcellulose, (C) filled starch hydrogels containing 0.05% methylcellulose; and (D) filled starch hydrogels containing 0.2% methylcellulose.</P> <P>[DISPLAY OMISSION]</P>

Preparation and Characterization of Water/Oil/Water Emulsions Stabilized by Polyglycerol Polyricinoleate and Whey Protein Isolate

Mun, Saehun,Choi, Yongdoo,Rho, Shin-Joung,Kang, Choon-Gil,Park, Chan-Ho,Kim, Yong-Ro Wiley (Blackwell Publishing) 2010 Journal of Food Science Vol.75 No.2

Synergistic effect of ulleungdo stonecrop with licorice-rosemary extract emulsion on antibacterial activity

Shinjae Park,Saehun Mun,Yong-ro Kim 한국산업식품공학회 2017 학술대회 및 심포지엄 Vol.2017 No.11

Licorice and rosemary contain a number of natural phenolic compounds which have a strong antibacterial and antioxidant activity. Ulleungdo stonecrop (US, scientific name: Sedum takesimense Nakai), indigenous island, is also known as a good antibiotic agent and skin whitening agent and is regarded as a promising materials in cosmetics field. Although the antibacterial activity of each material have been reported, little is known about the effect of using them together. Therefore, the purpose of this study was to investigate the synergistic effect on antibacterial activity when licorice and rosemary extract and US were used together. Since licorice and rosemary are lipid soluble materials and US is water soluble material, oil in water (O/W) emulsion system was used for this study. To manufacture O/W emulsions containing three kinds materials, first licorice and rosemary extracts and US was dispersed in soy bean oil and phosphate buffer (pH7) respectively. Decaglyceryl laurate was used as an emulsifier. There was slight decrease (-0.09~-0.46 Δlog) in the number of bacteria when O/W emulsion containing 300ppm of each licorice and rosemary extracts was mixed into B.subtilis. However, adding US (2,700ppm) into aqueous phase caused the rapid decrease in the amount of bacteria to -1.71 ~ -2.96 Δlog which were much higher decrement than US only in normal emulsion (-1.64 Δlog). In particular, there was a noticeable synergistic effect when rosemary extract and US was used together. The results obtained from this study could provide useful information for utilizing licorice and rosemary extracts and US as functional materials in the food and cosmetic areas.