25 results on '"Cheong WS"'
Search Results
2. Bat ASC2 suppresses inflammasomes and ameliorates inflammatory diseases.
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Ahn M, Chen VC, Rozario P, Ng WL, Kong PS, Sia WR, Kang AEZ, Su Q, Nguyen LH, Zhu F, Chan WOY, Tan CW, Cheong WS, Hey YY, Foo R, Guo F, Lim YT, Li X, Chia WN, Sobota RM, Fu NY, Irving AT, and Wang LF
- Subjects
- Animals, Humans, Mice, COVID-19, SARS-CoV-2, Virus Physiological Phenomena, Apoptosis Regulatory Proteins metabolism, Chiroptera immunology, Inflammasomes immunology, Ribonucleoproteins metabolism, Virus Diseases immunology
- Abstract
Bats are special in their ability to live long and host many emerging viruses. Our previous studies showed that bats have altered inflammasomes, which are central players in aging and infection. However, the role of inflammasome signaling in combating inflammatory diseases remains poorly understood. Here, we report bat ASC2 as a potent negative regulator of inflammasomes. Bat ASC2 is highly expressed at both the mRNA and protein levels and is highly potent in inhibiting human and mouse inflammasomes. Transgenic expression of bat ASC2 in mice reduced the severity of peritonitis induced by gout crystals and ASC particles. Bat ASC2 also dampened inflammation induced by multiple viruses and reduced mortality of influenza A virus infection. Importantly, it also suppressed SARS-CoV-2-immune-complex-induced inflammasome activation. Four key residues were identified for the gain of function of bat ASC2. Our results demonstrate that bat ASC2 is an important negative regulator of inflammasomes with therapeutic potential in inflammatory diseases., Competing Interests: Declaration of interests L.-F.W., M.A., and V.C.-W.C. are co-inventors of a patent application based on findings from the study., (Copyright © 2023 Elsevier Inc. All rights reserved.)
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- 2023
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3. Enhanced Soft 3D Reconstruction Method with an Iterative Matching Cost Update Using Object Surface Consensus.
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Lee MJ, Um GM, Yun J, Cheong WS, and Park SY
- Abstract
In this paper, we propose a multi-view stereo matching method, EnSoft3D (Enhanced Soft 3D Reconstruction) to obtain dense and high-quality depth images. Multi-view stereo is one of the high-interest research areas and has wide applications. Motivated by the Soft3D reconstruction method, we introduce a new multi-view stereo matching scheme. The original Soft3D method is introduced for novel view synthesis, while occlusion-aware depth is also reconstructed by integrating the matching costs of the Plane Sweep Stereo (PSS) and soft visibility volumes. However, the Soft3D method has an inherent limitation because the erroneous PSS matching costs are not updated. To overcome this limitation, the proposed scheme introduces an update process of the PSS matching costs. From the object surface consensus volume, an inverse consensus kernel is derived, and the PSS matching costs are iteratively updated using the kernel. The proposed EnSoft3D method reconstructs a highly accurate 3D depth image because both the multi-view matching cost and soft visibility are updated simultaneously. The performance of the proposed method is evaluated by using structured and unstructured benchmark datasets. Disparity error is measured to verify 3D reconstruction accuracy, and both PSNR and SSIM are measured to verify the simultaneous enhancement of view synthesis.
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- 2021
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4. Diagnostic and therapeutic potential of shark variable new antigen receptor (VNAR) single domain antibody.
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Cheong WS, Leow CY, Abdul Majeed AB, and Leow CH
- Subjects
- Animals, Antibodies, Monoclonal immunology, Antibodies, Monoclonal therapeutic use, Fish Proteins immunology, Fish Proteins therapeutic use, Receptors, Antigen immunology, Receptors, Antigen therapeutic use, Sharks immunology, Single-Chain Antibodies immunology, Single-Chain Antibodies therapeutic use
- Abstract
Conventional monoclonal antibodies (mAbs) have been widely used in research and diagnostic applications due to their high affinity and specificity. However, multiple limitations, such as large size, complex structure and sensitivity to extreme ambient temperature potentially weaken the performance of mAbs in certain applications. To address this problem, the exploration of new antigen binders is extensively required in relation to improve the quality of current diagnostic platforms. In recent years, a new immunoglobulin-based protein, namely variable domain of new antigen receptor (VNAR) was discovered in sharks. Unlike conventional mAbs, several advantages of VNARs, include small size, better thermostability and peculiar paratope structure have attracted interest of researchers to further explore on it. This article aims to first present an overview of the shark VNARs and outline the characteristics as an outstanding new reagent for diagnostic and therapeutic applications., Competing Interests: Declaration of competing interest The authors declare that they have no competing interests., (Copyright © 2020 Elsevier B.V. All rights reserved.)
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- 2020
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5. Effect of Inductively Coupled Plasma on Multilayer Electrodes for Flexible Single-Layer Touch Screen Panels.
- Author
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Hong CH, Lee JM, Kim YH, and Cheong WS
- Abstract
We investigated the effect of inductively coupled plasma (ICP) on multilayer electrodes for flexible capacitive touch sensors. We found that using ICP during Ag deposition generally increased the conductivity and transmittance of multilayer electrodes. As a result, in the case of the multilayer electrode with an ICP power of 150 W during Ag deposition, 5.7 Ω/sq of sheet resistance and 89.6% of transmittance (550 nm) have been achieved. We demonstrate that the crystallization of the ICP supplied Ag layer in multilayer electrodes leads to the smooth surface roughness of the multilayer film; the smooth surface roughness provided low light scattering. As a result, the crystallized Ag thin film by ICP improved the sheet resistance and transmittance of multilayer electrodes. Finally, we fabricated a 221 × 130 mm (active layer)-sized single-layer touch screen panel (TSP) using multilayer electrodes with ICP on a corning glass and polyethylene terephthalate flexible substrate. The single-layer TSPs show high linearity and sensitivity with multitouches.
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- 2019
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6. Erratum: E3 Ubiquitin ligase ZNRF4 negatively regulates NOD2 signalling and induces tolerance to MDP.
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Bist P, Cheong WS, Ng A, Dikshit N, Kim BH, Pulloor NK, Khameneh HJ, Hedl M, Shenoy AR, Balamuralidhar V, Malik NBA, Hong M, Neutzner A, Chin KC, Kobayashi KS, Bertoletti A, Mortellaro A, Abraham C, MacMicking JD, Xavier RJ, and Sukumaran B
- Abstract
This corrects the article DOI: 10.1038/ncomms15865.
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- 2017
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7. E3 Ubiquitin ligase ZNRF4 negatively regulates NOD2 signalling and induces tolerance to MDP.
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Bist P, Cheong WS, Ng A, Dikshit N, Kim BH, Pulloor NK, Khameneh HJ, Hedl M, Shenoy AR, Balamuralidhar V, Malik NBA, Hong M, Neutzner A, Chin KC, Kobayashi KS, Bertoletti A, Mortellaro A, Abraham C, MacMicking JD, Xavier RJ, and Sukumaran B
- Subjects
- Acetylmuramyl-Alanyl-Isoglutamine immunology, Animals, DNA-Binding Proteins genetics, DNA-Binding Proteins immunology, HEK293 Cells, Humans, Listeria monocytogenes pathogenicity, Listeriosis immunology, Listeriosis metabolism, Mice, Inbred C57BL, Mice, Mutant Strains, Monocytes metabolism, NF-kappa B metabolism, Nod2 Signaling Adaptor Protein genetics, Receptor-Interacting Protein Serine-Threonine Kinase 2 metabolism, Signal Transduction physiology, Ubiquitination drug effects, Acetylmuramyl-Alanyl-Isoglutamine pharmacology, DNA-Binding Proteins metabolism, Immune Tolerance drug effects, Nod2 Signaling Adaptor Protein metabolism
- Abstract
Optimal regulation of the innate immune receptor nucleotide-binding oligomerization domain-containing protein 2 (NOD2) is essential for controlling bacterial infections and inflammatory disorders. Chronic NOD2 stimulation induces non-responsiveness to restimulation, termed NOD2-induced tolerance. Although the levels of the NOD2 adaptor, RIP2, are reported to regulate both acute and chronic NOD2 signalling, how RIP2 levels are modulated is unclear. Here we show that ZNRF4 induces K48-linked ubiquitination of RIP2 and promotes RIP2 degradation. A fraction of RIP2 localizes to the endoplasmic reticulum (ER), where it interacts with ZNRF4 under either 55 unstimulated and muramyl dipeptide-stimulated conditions. Znrf4 knockdown monocytes have sustained nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) activation, and Znrf4 knockdown mice have reduced NOD2-induced tolerance and more effective control of Listeria monocytogenes infection. Our results thus demonstrate E3-ubiquitin ligase ZNRF4-mediated RIP2 degradation as a negative regulatory mechanism of NOD2-induced NF-κB, cytokine and anti-bacterial responses in vitro and in vivo, and identify a ZNRF4-RIP2 axis of fine-tuning NOD2 signalling to promote protective host immunity.
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- 2017
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8. Dialysis disequilibrium syndrome: A preventable fatal acute complication.
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Mah DY, Yia HJ, and Cheong WS
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- Adolescent, Brain, Fatal Outcome, Humans, Male, Peritoneal Dialysis, Syndrome, Acute Kidney Injury, Brain Edema etiology, Renal Dialysis adverse effects
- Abstract
Dialysis disequilibrium syndrome (DDS) is a neurological disorder with varying severity that is postulated to be associated with cerebral oedema. We described a case of DDS resulting in irreversible brain injury and death following acute haemodialysis. A 13-year-old male with no past medical history and weighing 30kg, presented to hospital with severe urosepsis complicated by acute kidney injury (Creatinine 1422mmol/L; Urea 74.2mmol/L, Potassium 6.3mmol/L, Sodium 137mmol/L) and severe metabolic acidosis (pH 6.99, HC03 1.7mmol/L). Chest radiograph was normal. Elective intubation was done for respiratory distress. Acute haemodialysis performed due to refractory metabolic acidosis. Following haemodialysis, he became hypotensive which required inotropes. His Riker's score was low with absence of brainstem reflexes after withholding sedation. CT Brain showed generalised cerebral oedema consistent with global hypoxic changes involving the brainstem. The symptoms of DDS are caused by water movement into the brain causing cerebral oedema. Two theories have been proposed: reverse osmotic shift induced by urea removal and a fall in cerebral intracellular pH. Prevention is the key to the management of DDS. It is important to identify high risk patients and haemodialysis with reduced dialysis efficacy and gradual urea reduction is recommended. Patients who are vulnerable to DDS should be monitored closely. Low efficiency haemodialysis is recommended. Acute peritoneal dialysis might be an alternative option, but further studies are needed.
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- 2016
9. Electron beam irradiated silver nanowires for a highly transparent heater.
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Hong CH, Oh SK, Kim TK, Cha YJ, Kwak JS, Shin JH, Ju BK, and Cheong WS
- Abstract
Transparent heaters have attracted increasing attention for their usefulness in vehicle windows, outdoor displays, and periscopes. We present high performance transparent heaters based on Ag nanowires with electron beam irradiation. We obtained an Ag-nanowire thin film with 48 ohm/sq of sheet resistance and 88.8% (substrate included) transmittance at 550 nm after electron beam irradiation for 120 sec. We demonstrate that the electron beam creates nano-soldering at the junctions of the Ag nanowires, which produces lower sheet resistance and improved adhesion of the Ag nanowires. We fabricated a transparent heater with Ag nanowires after electron beam irradiation, and obtained a temperature of 51 °C within 1 min at an applied voltage of 7 V. The presented technique will be useful in a wide range of applications for transparent heaters.
- Published
- 2015
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10. Effect of Inductively Coupled Plasma on the Structural and Electrical Properties of Ti-Doped ITO Films Formed by IPVD.
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Hong CH, Shin JH, Park NM, Kim KH, Kim BS, Song CW, Yang JW, Seo WH, Ju BK, and Cheong WS
- Abstract
In this study, we investigated Ti-doped ITO films formed through ionized physical vapor deposition (IPVD) using inductively coupled plasma (ICP). Ti-doped ITO thin films showed an enhanced mobility with ICP power; owing to the improved crystallinity, and the sheet resistance of the Ti-doped ITO (30 nm) largely decreased from 295.1 to 134.5 ohm/sq, even during at room temperature. Therefore, IPVD technology offers a useful tool for transparent electrodes with a large area window-unified touch-screen panel.
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- 2015
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11. Design of quorum quenching microbial vessel to enhance cell viability for biofouling control in membrane bioreactor.
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Cheong WS, Kim SR, Oh HS, Lee SH, Yeon KM, Lee CH, and Lee JK
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- Biotechnology methods, Wastewater chemistry, Water Purification methods, Acyl-Butyrolactones metabolism, Biofouling prevention & control, Bioreactors microbiology, Membranes microbiology, Microbial Viability, Proteobacteria metabolism, Quorum Sensing
- Abstract
Quorum quenching (QQ) with a microbial vessel has recently been reported as an economically feasible biofouling control platform in a membrane bioreactor (MBR) for wastewater treatment. In this study, a quorum quenching MBR with a ceramic microbial vessel (CMV) was designed to overcome the extremely low F/M ratio inside a microbial vessel. The CMV was prepared with a monolithic ceramic microporous membrane and AHLdegrading QQ bacteria, Pseudomonas sp. 1A1. The "inner flow feeding mode" was introduced, under which fresh feed was supplied to the MBR only through the center lumen in the CMV. The inner flow feeding mode facilitated nutrient transport to QQ bacteria in the CMV and thus enabled relatively long-term maintenance of cell viability. The quorum quenching effect of the CMV on controlling membrane biofouling in the MBR was more pronounced with the inner flow feeding mode, which was identified by the slower increase in the transmembrane pressure as well as by the visual observation of a biocake that formed on the used membrane surface. In the QQ MBR with the CMV, the concentrations of extracellular polymeric substances were substantially decreased in the biocake on the membrane surface compared with those in the conventional MBR. The CMV also showed its potential with effective biofouling control over long-term operation of the QQ MBR.
- Published
- 2014
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12. Biofouling inhibition in MBR by Rhodococcus sp. BH4 isolated from real MBR plant.
- Author
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Oh HS, Kim SR, Cheong WS, Lee CH, and Lee JK
- Subjects
- Acyl-Butyrolactones metabolism, Bacterial Proteins genetics, Bacterial Proteins metabolism, Carboxylic Ester Hydrolases genetics, Carboxylic Ester Hydrolases metabolism, Membranes, Artificial, Molecular Sequence Data, Rhodococcus enzymology, Rhodococcus genetics, Bacterial Adhesion, Bioreactors microbiology, Quorum Sensing, Rhodococcus physiology
- Abstract
It has been reported that an indigenous quorum quenching bacterium, Rhodococcus sp. BH4, which was isolated from a real plant of membrane bioreactor (MBR) has promising potential to control biofouling in MBR. However, little is known about quorum quenching mechanisms by the strain BH4. In this study, various characteristics of strain BH4 were investigated to elucidate its behavior in more detail in the mixed liquor of MBR. The N-acyl homoserine lactone hydrolase (AHL-lactonase) gene of strain BH4 showed a high degree of identity to qsdA in Rhodococcus erythropolis W2. The LC-ESI-MS analysis of the degradation product by strain BH4 confirmed that it inactivated AHL activity by hydrolyzing the lactone bond of AHL. It degraded a wide range of N-acyl homoserine lactones (AHLs), but there was a large difference in the degradation rate of each AHL compared to other reported AHL-lactonase-producing strains belonging to Rhodococcus genus. Its quorum quenching activity was confirmed not only in the Luria-Bertani medium, but also in the synthetic wastewater. Furthermore, the amount of strain BH4 encapsulated in the vessel as well as the material of the vessel substantially affected the quorum quenching activity of strain BH4, which provides useful information, particularly for the biofouling control in a real MBR plant from an engineering point of view.
- Published
- 2013
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13. Index-matched indium tin oxide electrodes for capacitive touch screen panel applications.
- Author
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Hong CH, Shin JH, Ju BK, Kim KH, Park NM, Kim BS, and Cheong WS
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- Electric Capacitance, Equipment Design, Equipment Failure Analysis, Nanostructures ultrastructure, Particle Size, Touch, Electrodes, Electronics instrumentation, Lighting instrumentation, Nanostructures chemistry, Refractometry instrumentation, Tin Compounds chemistry, User-Computer Interface
- Abstract
Index-matched indium tin oxide (ITO) electrodes for capacitive touch screen panels have been fabricated to improve optical transmittance and reduce the difference of reflectance (deltaR) between the etched and un-etched regions. 8.5 nm Nb2O5 and 49 nm SiO2 thin films were deposited by magnetron sputtering as index-matching layers between an ITO electrode and a glass substrate. In case of 30 nm ITO electrode, a 4.3% improvement in the optical transmittance and a deltaR of less than 1% were achieved, along with a low sheet resistance of 90 omega/square.
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- 2013
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14. Characteristic corrosion resistance of nanocrystalline TiN films prepared by high density plasma reactive magnetron sputtering.
- Author
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Kim JH, Kang CG, Kim YT, Cheong WS, and Song PK
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- Corrosion, Hot Temperature, Macromolecular Substances chemistry, Magnets, Materials Testing, Molecular Conformation, Particle Size, Surface Properties, Crystallization methods, Membranes, Artificial, Nanostructures chemistry, Nanostructures ultrastructure, Plasma Gases chemistry, Titanium chemistry
- Abstract
Nanocytalline TiN films were deposited on non-alkali glass and Al substrates by reactive DC magnetron sputtering (DCMS) with an electromagnetic field system (EMF). The microstructure and corrosion resistance of the TiN-coated Al substrates were estimated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical methods. All the TiN films shows that they have a (111) preferred orientation at room temperature. TiN films deposited on Al substrate using only DCMS 400 W showed a sheet resistance of 3.22 x 10-1 omega/symbol see texts (resistivity, 3.22 x 10-5 omegacm). On the other hand, a relatively low sheet resistance of 1.91 x 10-1 omega/symbol see text (1.91 x 10-5 omegacm) was obtained for the dense nanocrystalline TiN film deposited on Al substrate using DCMS 375 W+ EMF 25 W, indicating that the introduction of an EMF system enhanced the electrical properties of the TiN film. TiN films deposited on Al substrate at 400 degreesC had a (200) preferred orientation with the lowest sheet resistance of 1.28x10-1 omega/symbol see texts (1.28 x 10-5 omegacm) which was attributed to reduced nano size defects and an improvement of the crystallinity. Potentiostatic and Potentiodynamic tests with a TiN-coated Al showed good corrosion resistance (l/corr, = 2.03 microA/cm2, Ecorr = -348 mV) compared to the uncoated Al substrate (/corr = 4.45 microA/cm2, Ecorr = -650 mV). Furthermore, EMF system showed that corrosion resistance of the TiN film also was enhanced compared to DCMS only. For the TiN film deposited on Al substrate at 400 degreesC, corrosion current and potential was 0.63 micro/cm2 and -1.5 mV, respectively. This improved corrosion resistance of the TiN film could be attributed to the densification of the film caused by enhancement of nitrification with increasing high reactive nitrogen radicals.
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- 2013
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15. Hepatitis B virus-like particles access major histocompatibility class I and II antigen presentation pathways in primary dendritic cells.
- Author
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Moffat JM, Cheong WS, Villadangos JA, Mintern JD, and Netter HJ
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- Animals, Antigen-Presenting Cells immunology, Cross-Priming, Dendritic Cells classification, Epitopes immunology, Hepatitis B virus immunology, Immunity, Cellular, Interferon-alpha immunology, Mice, Inbred C57BL, Ovalbumin immunology, T-Lymphocytes immunology, Antigen Presentation, Dendritic Cells immunology, Histocompatibility Antigens Class I immunology, Histocompatibility Antigens Class II immunology, Viral Envelope Proteins immunology
- Abstract
Virus-like particles (VLPs) represent high density displays of viral proteins that efficiently trigger immunity. VLPs composed of the small hepatitis B virus envelope protein (HBsAgS) are useful vaccine platforms that induce humoral and cellular immune responses. Notably, however, some studies suggest HBsAgS VLPs impair dendritic cell (DC) function. Here we investigated HBsAgS VLP interaction with DC subsets and antigen access to major histocompatibility complex (MHC) class I and II antigen presentation pathways in primary DCs. HBsAgS VLPs impaired plasmacytoid DC (pDC) interferon alpha (IFNα) production in response to CpG in vitro, but did not alter conventional DC (cDC) or pDC phenotype when administered in vivo. To assess cellular immune responses, HBsAgS VLPs were generated containing the ovalbumin (OVA) model epitopes OVA(257-264) and OVA(323-339) to access MHCI and MHCII antigen presentation pathways, respectively; both in vitro and following immunisation in vivo. HBsAgS VLP-OVA(257-264) elicited CTL responses in vivo that were not enhanced by inclusion of an additional MHCII helper epitope. HBsAgS VLP-OVA(257-264) administered in vivo was cross-presented by CD8(+) DCs, but not CD8(-) DCs. Therefore, HBsAgS VLPs can deliver antigen to both MHCI and MHCII antigen presentation pathways in primary DCs and promote cytotoxic and helper T cell priming despite their suppressive effect on pDCs., (Copyright © 2013 Elsevier Ltd. All rights reserved.)
- Published
- 2013
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16. Thin film transistor based on TiOx prepared by DC magnetron sputtering.
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Chung SM, Shin JH, Hong CH, and Cheong WS
- Abstract
This paper reports on the thin film transistor (TFT) based on TiOx prepared by direct current (DC) magnetron sputtering for the application of n-type channel transparent TFTs. A ceramic TiOx target was prepared for the sputtering of the TiO2 films. The structural, optical, and electrical properties of the TiO2 films were investigated after their heat treatment. It is observed from XRD measurement that the TiO2 films show anatase structure having (101), (004), and (105) planes after heat treatment. The anatase-structure TiO2 films show a band-gap energy of approximately 3.20 eV and a transmittance of approximately 91% (@550 nm). The bottom-gate TFTs fabricated with the TiO2 film as an n-type channel layer. These devices exhibit the on-off ratio, the field-effect mobility, and the threshold voltage of about 10(4), 0.002 cm2/Vs, and 6 V, respectively. These results indicate the possibility of applying TiO2 films depositied by DC magnetron sputtering to TiO2-based opto-electronic devices.
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- 2012
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17. Current stress induced electrical instability in transparent zinc tin oxide thin-film transistors.
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Cheong WS, Shin JH, Chung SM, Hwang CS, Lee JM, and Lee JH
- Abstract
Transparent zinc tin oxide thin-film transistors (ZTO-TFTs) [Zn:Sn = 4:1-2:1] have been fabricated so as to estimate the electrical instability under constant current stress. The relative intensity of the drain current noise power spectra density has been shown to have a typical 1/f-noise character, and it is implied that the mobility fluctuation in ZTO-TFT [Zn:Sn = 4:1] can be enhanced by a short-range ordering in amorphous Zn-Sn-oxide, causing a larger shift of the threshold voltage (deltaV(th)).
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- 2012
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18. Modulation of the immunogenicity of virus-like particles composed of mutant hepatitis B virus envelope subunits.
- Author
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Cheong WS, Hyakumura M, Yuen L, Warner N, Locarnini S, and Netter HJ
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- Amino Acid Substitution, Animals, Cell Line, Female, Hepatitis B virology, Hepatitis B Surface Antigens chemistry, Hepatitis B Vaccines chemistry, Hepatitis B Vaccines genetics, Hepatitis B Vaccines immunology, Hepatitis B virus chemistry, Hepatitis B virus genetics, Hepatitis B virus physiology, Humans, Immunization, Male, Mice, Mice, Inbred BALB C, Mutation, Virion chemistry, Virion genetics, Virion physiology, Virus Assembly, Hepatitis B immunology, Hepatitis B Surface Antigens genetics, Hepatitis B Surface Antigens immunology, Hepatitis B virus immunology, Virion immunology
- Abstract
Virus-like particles (VLPs) are non-infectious subviral protein complexes, which possess structural features identical or closely related to infectious virions. They are utilized as delivery tools for immunologically relevant antigenic sequences. In order to investigate whether mutant subunits can modulate the VLP immunogenicity, comparative immunization studies with wild-type and non-native VLPs were performed. To determine whether disulfide bonding impacts on the immunogenicity of hepatitis B virus envelope proteins (HBsAg), mutant HBsAg subunits with single, double and triple cysteine residue substitutions were generated. The mutant proteins were expressed in cell culture, secretion competent non-native VLPs generated, followed by immunization studies in mice to measure the cellular immune response. The reduced ability of mutant HBsAg proteins to form disulfide bonds does not interfere with their ability to assemble into secretion competent VLPs. Depending on specific cysteine to alanine changes, VLPs could be generated with or without an increased ratio of monomeric versus dimeric/oligomeric subunits compared to wild-type VLPs. The utilization of non-native VLPs resulted in enhanced cellular immune responses and does not seem to depend on the ratio between monomeric or dimeric/oligomeric subunits. Comparative immunization studies strongly indicate that changes in the disulfide bonding modulate the VLP immunogenicity most likely due to structural changes. We hypothesize that structural features have evolved with reduced immunogenicity to evade the constraints imposed by the immune system. Altering VLP conformation may represent an attractive strategy to modulate antigen processing resulting in an enhanced immune response and/or a changed hierarchy of epitope presentation., (Copyright © 2011 Elsevier B.V. All rights reserved.)
- Published
- 2012
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19. Structural and optical properties of Cu doped ZnO thin films by co-sputtering.
- Author
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Chung SM, Shin JH, Lee JM, Ryu MK, Cheong WS, Park SH, Hwang CS, and Cho KI
- Abstract
This paper reports on the structural and optical properties of ZnCuO thin films that were prepared by co-sputtering for the application of p-type-channel transparent thin-film transistors (TFTs). Pure ceramic ZnO and metal Cu targets were prepared for the co-sputtering of the ZnCuO thin films. The effects of the Cu concentration on the structural, optical, and electrical properties of the ZnCuO films were investigated after their heat treatment. It was observed from the XRD measurements that the ZnCuO films with a Cu concentration of 7% had ZnO(002), Cu2O(111), and Cu2O(200) planes. The 7% Cu-doped ZnO films also showed a band-gap energy of approximately 2.05 eV, an average transmittance of approximately 62%, and a p-type carrier density of approximately 1.33 x 10(19) cm-3 at room temperature. The bottom-gated TFTs that were fabricated with the ZnCuO thin film as a p-type channel exhibited an on-off ratio of approximately 6. These results indicate the possibility of applying ZnCuO thin films with variable band-gap energies to ZnO-based optoelectronic devices.
- Published
- 2011
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20. Delivery of a foreign epitope by sharing amino acid residues with the carrier matrix.
- Author
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Cheong WS, Drummer HE, and Netter HJ
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- Animals, Base Sequence, Epitopes genetics, Hepacivirus genetics, Hepatitis B Antibodies blood, Hepatitis B Surface Antigens genetics, Hepatitis B Surface Antigens immunology, Mice, Mice, Inbred BALB C, Molecular Sequence Data, Recombinant Fusion Proteins genetics, Recombinant Fusion Proteins immunology, Vaccines, Synthetic genetics, Vaccines, Synthetic immunology, Vaccines, Virosome genetics, Vaccines, Virosome immunology, Viral Envelope Proteins genetics, Epitopes immunology, Hepacivirus immunology, Viral Envelope Proteins immunology
- Abstract
A broad range of structural viral proteins has the ability to assemble into virus-like particles (VLPs). Under the condition that modified subunits are still competent to assemble into VLPs, they are epitope delivery platforms suitable for vaccination purposes. The insertion of foreign sequences can be detrimental for the formation of chimeric VLPs as a result of misfolded subunit proteins. Hence, a strategy was adopted to screen for locations allowing the use of shared residues between the wildtype subunit sequence and the foreign insert. The insertion of a cysteine-containing sequence of hepatitis C virus (HCV) envelope protein 2 (E2) without adding an additional cysteine residue retained the ability of recombinant small hepatitis B surface antigen (HBsAg-S) to form secretion competent VLPs. A cysteine residue shared by the insert and the template protein avoided the formation of non-native disulfide bonds, and allowed the formation of VLPs. The chimeric HBsAg-S VLPs were similar to wildtype VLPs in density exposing the inserted foreign epitope and being immunogenic. Overall, the use of shared sequences between the insert and the subunit will facilitate the design of chimeric VLPs carrying multiple epitopes.
- Published
- 2009
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21. Chimeric virus-like particles for the delivery of an inserted conserved influenza A-specific CTL epitope.
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Cheong WS, Reiseger J, Turner SJ, Boyd R, and Netter HJ
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- Animals, Cytokines metabolism, Cytotoxicity Tests, Immunologic, Female, Hepatitis B virus genetics, Immunologic Memory, Influenza A virus genetics, Lymphocyte Subsets immunology, Male, Mice, Mice, Transgenic, Viral Matrix Proteins genetics, Viral Matrix Proteins immunology, Virosomes genetics, Virosomes immunology, Epitopes, T-Lymphocyte immunology, Influenza Vaccines genetics, Influenza Vaccines immunology, Orthomyxoviridae Infections immunology
- Abstract
The small hepatitis B virus surface antigens (HBsAg-S) have the ability to self-assemble with host-derived lipids into empty non-infectious virus-like particles (VLPs). HBsAg-S VLPs are the sole component of the licensed hepatitis B vaccine, and they are a useful delivery platform for foreign epitopes. To develop VLPs capable of transporting foreign cytotoxic T lymphocyte (CTL) epitopes, HBsAg-S specific CTL epitopes at various sites were substituted with a conserved CTL epitope derived from the influenza matrix protein. Depending on the insertion site, the introduction of the MHC class I A2.1-restricted influenza epitope was compatible with the secretion competence of HBsAg-S indicating that chimeric VLPs were assembled. Immunizations of transgenic HHDII mice with chimeric VLPs induced anti-influenza CTL responses proving that the inserted foreign epitope can be correctly processed and cross-presented. Chimeric VLPs in the absence of adjuvant were able to induce memory T cell responses, which could be recalled by influenza virus infections in the mouse model system. The ability of chimeric HBsAg-S VLPs to induce anti-foreign CTL responses and also with the proven ability to induce humoral immune responses constitute a highly versatile platform for the delivery of selected multiple epitopes to target disease associated infectious agents.
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- 2009
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22. Quorum sensing: a new biofouling control paradigm in a membrane bioreactor for advanced wastewater treatment.
- Author
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Yeon KM, Cheong WS, Oh HS, Lee WN, Hwang BK, Lee CH, Beyenal H, and Lewandowski Z
- Subjects
- Acyl-Butyrolactones, Biodegradation, Environmental drug effects, Biofilms drug effects, Extracellular Space drug effects, Extracellular Space metabolism, Filtration, Flocculation, Glucose pharmacology, Polysaccharides metabolism, Bioreactors, Membranes, Artificial, Quorum Sensing drug effects, Waste Disposal, Fluid, Water Purification methods
- Abstract
Bacteria regulate specific group behaviors such as biofilm formation in response to population density using small signal molecules called autoinducers (quorum sensing, QS). In this study, the concept of bacterial QS was applied to membrane bioreactors (MBRs) for advanced wastewater treatment as a new biofouling control paradigm. The research was conducted in three phases: (1) demonstrate the presence of the autoinducer signal in MBRs, (2) correlate QS activity and membrane biofouling, (3) apply QS-based membrane biofouling control. A bioassay with Agrobacterium tumefaciens reporter strain proved that N-acyl homoserine lactone (AHL) autoinducers were produced in the MBR. Furthermore, thin-layer chromatographic analysis identified at least three different AHLs in the biocake, of which N-octanoyl-homoserine lactone was the most abundant During continuous MBR operation, the biocake showed strong AHL activity simultaneously with abrupt increase in the transmembrane pressure, which implies that QS is in close association with membrane biofouling. Porcine kidney acylase I, which can inactivate the AHL molecule by amide bond cleavage, was confirmed to prevent membrane biofouling by quenching AHL autoinducers. From these results, it was concluded that QS could be a novel target for biofouling control in MBRs.
- Published
- 2009
- Full Text
- View/download PDF
23. The academic environment: the students' perspective.
- Author
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Divaris K, Barlow PJ, Chendea SA, Cheong WS, Dounis A, Dragan IF, Hamlin J, Hosseinzadeh L, Kuin D, Mitrirattanakul S, Mo'nes M, Molnar N, Perryer G, Pickup J, Raval N, Shanahan D, Songpaisan Y, Taneva E, Yaghoub-Zadeh S, West K, and Vrazic D
- Subjects
- Educational Measurement methods, Human Development, Humans, Learning, Mental Health, Quality of Life, Social Behavior, Social Environment, Teaching methods, Attitude, Education, Dental, Students, Dental
- Abstract
Dental education is regarded as a complex, demanding and often stressful pedagogical procedure. Undergraduates, while enrolled in programmes of 4-6 years duration, are required to attain a unique and diverse collection of competences. Despite the major differences in educational systems, philosophies, methods and resources available worldwide, dental students' views regarding their education appear to be relatively convergent. This paper summarizes dental students' standpoint of their studies, showcases their experiences in different educational settings and discusses the characteristics of a positive academic environment. It is a consensus opinion that the 'students' perspective' should be taken into consideration in all discussions and decisions regarding dental education. Moreover, it is suggested that the set of recommendations proposed can improve students' quality of life and well-being, enhance their total educational experience and positively influence their future careers as oral health physicians. The 'ideal' academic environment may be defined as one that best prepares students for their future professional life and contributes towards their personal development, psychosomatic and social well-being. A number of diverse factors significantly influence the way students perceive and experience their education. These range from 'class size', 'leisure time' and 'assessment procedures' to 'relations with peers and faculty', 'ethical climate' and 'extra-curricular opportunities'. Research has revealed that stress symptoms, including psychological and psychosomatic manifestations, are prevalent among dental students. Apparently some stressors are inherent in dental studies. Nevertheless, suggested strategies and preventive interventions can reduce or eliminate many sources of stress and appropriate support services should be readily available. A key point for the Working Group has been the discrimination between 'teaching' and 'learning'. It is suggested that the educational content should be made available to students through a variety of methods, because individual learning styles and preferences vary considerably. Regardless of the educational philosophy adopted, students should be placed at the centre of the process. Moreover, it is critical that they are encouraged to take responsibility for their own learning. Other improvements suggested include increased formative assessment and self-assessment opportunities, reflective portfolios, collaborative learning, familiarization with and increased implementation of information and communication technology applications, early clinical exposure, greater emphasis on qualitative criteria in clinical education, community placements, and other extracurricular experiences such as international exchanges and awareness of minority and global health issues. The establishment of a global network in dental education is firmly supported but to be effective it will need active student representation and involvement.
- Published
- 2008
- Full Text
- View/download PDF
24. Impact of a non-meltable additive on melt agglomeration with a hydrophobic meltable binder in high-shear mixer.
- Author
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Cheong WS, Heng PW, and Wong TW
- Subjects
- Cottonseed Oil chemistry, Crystallization, Particle Size, Porosity, Powders chemistry, Rheology, Surface Tension, Technology, Pharmaceutical methods, Tensile Strength, Viscosity, Wettability, Chemistry, Pharmaceutical, Chlorpheniramine chemistry, Excipients chemistry, Lactose chemistry
- Abstract
The present study aims to investigate the behavior of melt agglomeration with a low-viscosity hydrophobic meltable binder by using a non-meltable additive. The size, crushing strength, and pore size distribution of resultant agglomerates, the rheological, surface tension, and wetting properties of the molten binder, as well as, the flow characteristics of preagglomeration powder blend were determined. The use of additive showed contradictory agglomerate growth-promoting and -retarding effects on the molten binder surface tension and the interparticulate frictional forces. Critical concentration effects of additive corresponded to threshold transition of agglomeration-promoting to -retarding behavior were discussed.
- Published
- 2007
- Full Text
- View/download PDF
25. Investigation of melt agglomeration process with a hydrophobic binder in combination with sucrose stearate.
- Author
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Heng PW, Wong TW, and Cheong WS
- Subjects
- Adhesiveness, Algorithms, Chemical Phenomena, Chemistry, Pharmaceutical, Chemistry, Physical, Cottonseed Oil chemistry, Hydrogenation, Lactose, Particle Size, Surface Tension, Viscosity, Excipients chemistry, Sucrose analogs & derivatives, Sucrose chemistry
- Abstract
The melt agglomeration process of lactose powder with hydrogenated cottonseed oil (HCO) as the hydrophobic meltable binder was investigated by studying the physicochemical properties of molten HCO modified by sucrose stearates S170, S770 and S1570. The size, size distribution, micromeritic and adhesion properties of agglomerates as well as surface tension, contact angle, viscosity and specific volume of molten HCO, with and without sucrose stearates, were examined. The viscosity, specific volume and surface tension of molten HCO were found to be modified to varying extents by sucrose stearates which are available in different HLB values and melt properties. The growth of melt agglomerates was promoted predominantly by an increase in viscosity, an increase in specific volume or a decrease in surface tension of the molten binding liquid. The agglomerate growth propensity was higher with an increase in inter-particulate binding strength, agglomerate surface wetness and extent of agglomerate consolidation which enhanced the liquid migration from agglomerate core to periphery leading to an increased surface plasticity for coalescence. The inclusion of high concentrations of completely meltable sucrose stearate S170 greatly induced the growth of agglomerates through increased specific volume and viscosity of the molten binding liquid. On the other hand, the inclusion of incompletely meltable sucrose stearates S770 and S1570 promoted the agglomeration mainly via the reduction in surface tension of the molten binding liquid with declining agglomerate growth propensity at high sucrose stearate concentrations. In addition to being an agglomeration modifier, sucrose stearate demonstrated anti-adherent property in melt agglomeration process. The properties of molten HCO and melt agglomerates were dependent on the type and concentration of sucrose stearate added.
- Published
- 2003
- Full Text
- View/download PDF
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