Publications by authors named "Si-Won Kim"

is a foodborne pathogen that can cause a potentially life-threatening infection, and almost all cases of human listeriosis are caused by isolates in serotypes 1/2a, 1/2b, 1/2c, and 4b. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is a rapid, accurate, and high-throughput tool for clinical diagnosis and microbiological research. In the current study, we examined the potential of MALDI-TOF MS for rapid identification of the foodborne pathogen and to identify high-risk serotypes.

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Aim: Bacteria naturally produce membrane vesicles (MVs), which have been shown to contribute to the spread of multi-drug resistant bacteria (MDR) by delivering antibiotic-resistant substances to antibiotic-susceptible bacteria. Here, we aim to show that MVs from Gram-positive bacteria are capable of transferring β-lactam antibiotic-resistant substances to antibiotic-sensitive Gram-negative bacteria.

Materials And Methods: MVs were collected from a methicillin-resistant strain of Staphylococcus aureus (MRSA) and vesicle-mediated fusion with antimicrobial-sensitive Escherichia coli (RC85).

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Viral hemorrhagic septicemia (VHS), caused by viral hemorrhagic septicemia virus (VHSV), is a viral disease affecting teleosts, and is the major cause of virus-related deaths in olive flounder (). Research has focused on ways to control VHS, and recently, the use of polyinosinic-polycytidylic acid poly (I:C)-potentiated vaccination has been investigated, whereby fish are injected with poly (I:C) and then with live pathogenic virus, resulting in a significant decrease in VHSV-related mortality. T cell responses were investigated in the present study after vaccinating olive flounder with poly (I:C)-potentiated vaccination to understand the ability of poly (I:C) to induce T cell immunity.

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The causative agent of acute hepatopancreatic necrosis disease (AHPND) is the bacterium, , which secretes toxins into the gastrointestinal tract of its host. toxins A and B (PirA/PirB) have been implicated in the pathogenesis of this disease, and are, therefore, the focus of studies developing treatments for AHPND. We previously produced recombinant antibodies based on the hagfish variable lymphocyte receptor B (VLRB) capable of neutralizing some viruses, suggesting that this type of antibody may have a potential application for treatment of AHPND.

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Article Synopsis
  • Scientists found that bacteria called MRSA can release tiny bubbles called extracellular vesicles (EVs) that help them survive against antibiotics.
  • When the MRSA bacteria were under stress from a weak antibiotic, they produced a lot more EVs, about 22 times more than when they weren't stressed.
  • These special EVs contain proteins that can break down the antibiotics, helping MRSA and other nearby bacteria stay alive even when antibiotics are present.
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The presence of CD4 T lymphocytes has been described for several teleost species, while many of the main T cell subsets have not been characterized at a cellular level, because of a lack of suitable tools for their identification, e.g., monoclonal antibodies (mAbs) against cell markers.

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Gram-negative bacteria have an outer membrane inhibiting the entry of antibiotics. Porins, found within the outer membrane, are involved in regulating the permeability of β-lactam antibiotics. β-lactamases are enzymes that are able to inactivate the antibacterial properties of β-lactam antibiotics.

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The variable lymphocyte receptor (VLR) mediates the humoral immune response in jawless vertebrates, including lamprey () and hagfish (). Hagfish VLRBs are composed of leucine-rich repeat (LRR) modules, conjugated with a superhydrophobic C-terminal tail, which contributes to low levels of expression in recombinant protein technology. In this study, we screened Ag-specific VLRBs from hagfish immunized with nervous necrosis virus (NNV).

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The occurrence of CD4 helper T cells has already been established for a number of teleost species, though, it has not been possible to analyze these responses at a cellular level due to a large lack of appropriate monoclonal antibodies (mAbs). In the present study, we produced a mAb against olive flounder (Paralichthys olivaceus) CD4-1 lymphocyte to investigate the functional activity of the cells to improve our understanding of the T cell response in this species. This mAb is specifically able to detect CD4-1 lymphocytes in olive flounder proved by immunofluorescence staining and RT-PCR analysis.

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Background And Objective: Patients with mood disorders are known to have an emotion recognition deficit in facial emotion processing. Emotion perception involves two systems of cognitive and affective processes associated with brain activation in the fusiform gyrus and prefrontal cortices. To overcome the limitations of existing emotion perception tests, we designed an emotion perception index to assess the individuals' mood status.

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The dendrites of retinal ganglion cells (RGCs) synapse with the axon terminals of bipolar cells in the inner plexiform layer (IPL). Changes in the RGC dendrites and synapses between the bipolar cells in the inner retinal layer may critically alter the function of RGCs in glaucoma. The present study attempted to discover changes in the synapse using brain-derived neurotrophic factor (BDNF) after glaucoma induction by chronic intraocular pressure elevation in a rat model.

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We investigated the optical and electrical properties of a -Ga₂O₃/Ag/-Ga₂O₃ multilayer transparent conductive electrode deposited on an -Al2O₃ (0001) substrate. For the deposition of a continuous Ag layer, we preliminarily performed anultraviolet-ozone pretreatment of the Ga₂O₃ bottom layer. To obtain a stable -phase of Ga₂O₃, the -Ga₂O₃/Ag/-Ga₂O₃ multilayer was annealed at 700 °C under N₂ atmosphere.

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We propose a high efficiency flip chip-based ultraviolet (UV) emitter with aluminum (Al) reflector that includes indium tin oxide (ITO) nano grains for current injection between the Al and -AlGaN layer. Al has attracted attention as a reflector for high efficiency UV emitters because of its high reflectance in the UV region. To improve the efficiency of UV emitter, we generated periodic microhole arrays on the -AlGaN layer, which serve as a scattering center in the flip chip structure and enhance the light extraction efficiency.

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The variable lymphocyte receptor B (VLRB) of jawless vertebrates has a similar function to the antibodies produced by jawed vertebrates, and has been considered as an alternative source to mammalian antibodies for use in biological research. We developed a modified yeast display vector system (pYD8) to display recombinant hagfish VLRB proteins on the extracellular surface of yeast for the isolation of antigen-specific VLRBs. After observing an up-regulation in the VLRB response in hagfish immunized with hemagglutinin 1 of avian influenza virus H9N2 subtype (H9N2-HA1), the antigen-specific VLRBs decorated on the yeast's surface were selected by quantitative library screening through magnetic-activated cell sorting (MACS) and fluorescent-activated cell sorting (FACS).

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Background: The livestock industry requires high-quality products, as well as improved productivity. There have been many studies regarding the utilization of feed additives aiming to increase productivity, enhance immune functions and prevent infectious diseases in livestock. Biofunctional feed additives would be beneficial not only for animal health, but also for consumers.

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Lamprey, one of the living representatives of jawless vertebrates, uses variable lymphocyte receptors B (VLRB) for antigen recognition, rather than immunoglobulin (Ig) based receptors as used by higher vertebrates. The C-terminus of lamprey VLRB (LC) possess a glycosylphosphatidylinositol (GPI) signal sequence and seven cysteine residues providing dual functionality of the VLRB antibody in the form of a humoral agglutinin and cell membrane receptors. Here, we show that the LC can be either secreted or be membrane anchored as a heterologous fused protein in a multimeric form comprising of eight or ten monomeric units.

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The variable lymphocyte receptor (VLR) B of jawless vertebrates functions as a secreted Ab of jawed vertebrates and has emerged as an alternative Ab with a single polypeptide chain. After observing an upregulated VLRB response in hagfish immunized with avian influenza virus (AIV) subtype H9N2, we screened AIV H9N2-specific VLRB using a mammalian expression system. To improve the binding avidity of the Ag-specific VLRB to the Ag, we enabled multimerization of the VLRB by conjugating it with C-terminal domain of human C4b-binding protein.

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Monomeric variable lymphocyte receptor B (VLRB) is one of the smallest binding scaffold (20-25 kDa) from jawless vertebrates, hagfish and lamprey. This relatively new class of binding scaffold has various advantages: i) it has a single peptide composition, amenable to molecular engineering for enhancing its stability and affinity; ii) it has a small size, contributing better tissue penetration and easier production using microorganism expression system. Monomeric arVLRB142, which can specifically bind to the glycoprotein of viral hemorrhagic septicemia virus (VHSV), was expressed in Pichia pastoris.

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In hagfish and lampreys, two representative jawless vertebrates, the humoral immunity is directly mediated by variable lymphocyte receptors B (VLRBs). Both monomeric VLRBs are structurally and functionally similar, but their C-terminal tails differ: lamprey VLRB has a Cys-rich tail that forms disulfide-linked pentamers of dimers, contributing to its multivalency, whereas hagfish VLRB has a superhydrophobic tail of unknown structure. Here, we reveal that VLRBs obtained from hagfish plasma have a globular-shaped multimerized form (approximately 0.

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Variable lymphocyte receptors B (VLRBs) are non-immunoglobulin components of the humoral immune system in jawless vertebrates including hagfish (Eptatretus burgeri) and lamprey (Petromyzon marinus). Hagfish VLRBs consist of leucine rich repeat (LRR) modules with a superhydrophobic C-terminal tail, the latter of which leads to extremely low expression levels in recombinant protein technology. Here, we present an artificially oligomerized VLRB (arVLRB) that conjugates via the C4bp oligomerization domain derived from human C4b-binding protein (hC4bp) rather than the superhydrophobic tail.

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We investigated the effect of the Ag interlayer thickness on the structural, electrical and optical properties of FTO/Ag/FTO structures designed for use in wide bandgap transparent conducting electrodes. The top and bottom FTO layers were deposited on α-Al2O3 (0001) substrates via RF magnetron sputtering at 300 °C and Ag interlayers were deposited using an e-beam evaporator system. We optimized the figure of merit by changing the thickness of the inserted Ag interlayer from 10 nm to 14 nm, achieving a maximum value of 2.

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Outer membrane vesicles (OMVs) containing various bacterial compounds are released from mainly gram-negative bacteria. Secreted OMVs play important roles in the ability of a bacterium to defend itself, and thus contribute to the survival of bacteria in a community. In this study, we collected OMVs from β-lactam antibiotic-resistant Escherichia coli established by conjugation assay and the parental β-lactam antibiotic-susceptible strain, and performed comparative proteomic analysis to examine whether these OMVs carried β-lactam-resistant compounds.

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The purpose of this study was to investigate the effects of interleukin-37 (IL-37) on a Dermatophagoides farinae (Der f)-induced murine model of allergic rhinitis (AR). BALB/c mice, except the control groups, were sensitized intraperitoneally and challenged intranasally with Der f (Der f group). The IL-37 and IL-37+anti-CD25 groups were administered IL-37 intranasally.

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In mammals, germ cells originate outside of the developing gonads and follow a unique migration pattern through the embryonic tissue toward the genital ridges. Many studies have attempted to identify critical receptors and factors involved in germ cell migration. However, relatively few reports exist on germ cell receptors and chemokines that are involved in germ cell migration in avian species.

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