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Lee Ji Joo,Choe Young June,Jeong Hyeongseop,Kim Moonsu,Kim Seonggon,Yoo Hanna,Park Kunhee,Kim Chanhee,Choi Sojin,Sim JiWoo,Park Yoojin,Huh In Sil,Hong Gasil,Kim Mi Young,Song Jin Su,Lee Jihee,Kim Eun- 대한의학회 2021 Journal of Korean medical science Vol.36 No.50
In November 2021, 14 international travel-related severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) B.1.1.529 (omicron) variant of concern (VOC) patients were detected in South Korea. Epidemiologic investigation revealed community transmission of the omicron VOC. A total of 80 SARS-CoV-2 omicron VOC-positive patients were identified until December 10, 2021 and 66 of them reported no relation to the international travel. There may be more transmissions with this VOC in Korea than reported.
Structure of the Tripartite Multidrug Efflux Pump AcrAB-TolC Suggests an Alternative Assembly Mode
Kim, Jin-Sik,Jeong, Hyeongseop,Song, Saemee,Kim, Hye-Yeon,Lee, Kangseok,Hyun, Jaekyung,Ha, Nam-Chul Korean Society for Molecular and Cellular Biology 2015 Molecules and cells Vol.38 No.2
Escherichia coli AcrAB-TolC is a multidrug efflux pump that expels a wide range of toxic substrates. The dynamic nature of the binding or low affinity between the components has impeded elucidation of how the three components assemble in the functional state. Here, we created fusion proteins composed of AcrB, a transmembrane linker, and two copies of AcrA. The fusion protein exhibited acridine pumping activity, suggesting that the protein reflects the functional structure in vivo. To discern the assembling mode with TolC, the AcrBA fusion protein was incubated with TolC or a chimeric protein containing the TolC aperture tip region. Three-dimensional structures of the complex proteins were determined through transmission electron microscopy. The overall structure exemplifies the adaptor bridging model, wherein the funnel-like AcrA hexamer forms an intermeshing cogwheel interaction with the ${\alpha}$-barrel tip region of TolC, and a direct interaction between AcrB and TolC is not allowed. These observations provide a structural blueprint for understanding multidrug resistance in pathogenic Gram-negative bacteria.
Keum, Hyeongseop,Kim, Jin Yong,Yu, Byeongjun,Yu, Seung Jung,Kim, Jinjoo,Jeon, Hyungsu,Lee, Dong Yun,Im, Sung Gap,Jon, Sangyong American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.23
<P>As reports of multidrug resistant pathogens have increased, patients with implanted medical catheters increasingly need alternative solutions to antibiotic treatments. As most catheter-related infections are directly associated with biofilm formation on the catheter surface, which, once formed, is difficult to eliminate, a promising approach to biofilm prevention involves inhibiting the initial adhesion of bacteria to the surface. In this study, we report an amphiphilic, antifouling polymer, poly(DMA-mPEGMA-AA) that can facilely coat the surfaces of commercially available catheter materials in water and prevent bacterial adhesion to and subsequent colonization of the surface, giving rise to an antibiofilm surface. The antifouling coating layer was formed simply by dipping a model substrate (polystyrene, PET, PDMS, or silicon-based urinary catheter) in water containing poly(DMA-mPEGMA-AA), followed by characterization by X-ray photoelectron spectroscopy (XPS). The antibacterial adhesion properties of the polymer-coated surface were assessed for Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) growth under static (incubation in the presence of a bacterial suspension) and dynamic (bacteria suspended in a solution under flow) conditions. Regardless of the conditions, the polymer-coated surface displayed significantly reduced attachment of the bacteria (antiadhesion effect > similar to 8-fold) compared to the bare noncoated substrates. Treatment of the implanted catheters with S. aureus in vivo further confirmed that the polymer-coated silicon urinary catheters could significantly reduce bacterial adhesion and biofilm formation in a bacterial infection animal model. Furthermore, the polymer-coated catheters did not induce hemolysis and were resistant to the adhesion of blood-circulating cells, indicative of high biocompatibility. Collectively, the present amphiphilic antifouling polymer is potentially useful as a coating platform that renders existing medical devices resistant to biofilm formation.</P>
Jeong, Hyeongseop,Yoo, Seung Jo,Won, Jonghan,Lee, Hyun-Ju,Chung, Jeong Min,Kim, Han-ul,Kim, Gwang Joong,Kim, Jin-Gyu,Jung, Hyun Suk,Hyun, Jaekyung Elsevier 2018 Ultramicroscopy Vol.194 No.-
<P><B>Abstract</B></P> <P>Heavy metal compounds are adsorbed onto biological specimen in order to enhance the contrast as well as to preserve the structural features of the specimen against electron beam-induced radiation damage. In particular, in combination with computational image processing, negative staining is widely used for structural analysis of protein complexes to moderate resolutions. Image analysis of negatively stained biological specimen is known to suffer from limited achievable resolution due to dehydration and large grain size of staining molecules although the extent of such effect remains somewhat dubious.</P> <P>Stain molecules exist as grains under electron beam. However, clear observation of the crystalline nature of the grains and their association with biological specimen has not been thoroughly demonstrated. In this study, we attempted high-resolution TEM (HRTEM) using high voltage electron microscopy and electron crystallography analysis for the detailed characterization of negatively stained biological specimen, focusing on physical state and chemical composition of the stain molecules. The electron crystallography analysis allowed for the identification of the crystal constituents of widely used stains, hence revealing the chemical nature and the morphology of the stain molecules at specimen level. This study re-evaluated generally accepted notions on negative staining, and may help correctly interpreting the structural analysis of stained biological specimen.</P> <P><B>Highlights</B></P> <P> <UL> <LI> High voltage electron microscopy (HVEM) visualized nano-crystals surrounding of heavy metal-embedded biological specimen. </LI> <LI> Electron crystallography determined chemical composition of the stain molecules. </LI> <LI> The grain size of nano-crystals of stained molecules from uranyl acetate and uranyl formate were nearly identical, and consistent with that of uranium dioxide (UO<SUB>2</SUB>). </LI> <LI> It identified that UO<SUB>2</SUB> is the main contributor of image contrast of heavy metal-embedded biological specimen. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Ageism between Medical and Preliminary Medical Persons in Korea
Jiyeon Lee,Hyeongseop Yu,Hyun Hee Cho,MinWoo Kim,Seungrye Yang 대한노인병학회 2020 Annals of geriatric medicine and research Vol.24 No.1
Background: We tried to analyse the trends in ageism among health care providers and medical students in the Republic of Korea. Methods: We used the Fraboni Scale of Ageism (FSA), Relating to Older People Evaluation (ROPE) questionnaire, Anxiety about Aging Scale (AAS), and The Facts on Aging Quiz II to assess ageism in medical students (n=90), nurses (n=114), and doctors (n=83). We grouped health care providers based on the percentage of aged patients (over 65 years) that they treated. Results: Compared to the other groups, doctors had more knowledge about aging and the highest and lowest total scores in the FSA and ROPE, respectively. The total FSA scores and percentage of aged patients treated were negatively correlated. Regarding the ROPE score, negative and positive ageist behaviors were positively correlated with the percentage of aged patients. Conclusions: Ageism and ageist behavior among doctors differed from previous reports and other groups mentioned in the present study. Although doctors had more knowledge of aging, they had expressed a high levels of ageism. However, they did not act ageistically. Health care providers who treat a large number of older patients had minimal ageism but more ageist behavior. These findings may be attributed to the low completion rate of geriatric classes, lack of education on ageist behaviors, or Confucian education inculcating skepticism toward older adults.
Lee, Sangmin,Jeong, Hyeongseop,Lee, Ju Huck,Chung, Jeong Min,Kim, Rumi,Yun, Hyung Joong,Won, Jonghan,Jung, Hyun Suk Elsevier 2017 Biochemical and biophysical research communication Vol.489 No.2
<P><B>Abstract</B></P> <P>Alkyl hydroperoxide reductase E (AhpE) is a member of the peroxidase family of enzymes that catalyse the reduction of peroxides, however its structural and functional roles are still unclear in details. In this study, we used the <I>Thermococcus kodakarensis</I> AhpE-like protein as a model to investigate structure–function relationships including the molecular properties of DNA binding activity. Multiple sequence alignment, structural comparison and biochemical analyses revealed that TkAhpE includes conserved peroxidase residues in the active site, and exhibits peroxidase activity with structure-dependent holdase chaperone function. Following electrophoretic mobility shift assays and electron microscopy analysis demonstrated distinctive binding features of TkAhpE to the DNA showing that their dimeric conformer can bind to the double-stranded DNA, but not to the single-stranded DNA, indicating its striking molecular features to double-stranded DNA-specific interactions. Based on our results, we provided that TkAhpE is a multifunctional peroxidase displaying structure-dependent molecular chaperone and DNA binding activities.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Alkyl hydroperoxide reductase E acts as a multi-functional protein displaying peroxidase, holdase and DNA binding activities. </LI> <LI> Thermococcus kodakarensis AhpE(TkAhpE) exhibits peroxidase activities with structure-dependent holdase chaperone function. </LI> <LI> Recombinant TkAhpE is expressed as two different oligomeric forms, the dimeric and octameric conformers. </LI> <LI> Unlikely an octameric conformer, dimeric state of TkAhpE can bind both double stranded circular and linear DNA molecules. </LI> </UL> </P>