Publications by authors named "Youngjin Choi"

85 Publications

Comparison of Prediction Models for Mortality Related to Injuries from Road Traffic Accidents after Correcting for Undersampling.

Int J Environ Res Public Health 2021 May 24;18(11). Epub 2021 May 24.

Department of Healthcare Management, Eulji University, Seongnam 13135, Korea.

In this study, four models-logistic regression (LR), random forest (RF), linear support vector machine (SVM), and radial basis function (RBF)-SVM-were compared for their accuracy in determining mortality caused by road traffic injuries. They were tested using five years of national-level data from the Korea Disease Control and Prevention Agency's (KDCA) National Hospital Discharge In-Depth Survey (2013 through to 2017). Model performance was measured for accuracy, precision, recall, F1 score, and Brier score metrics using classification analysis that included characteristics of patients, accidents, injuries, and illnesses. Due to the number of variables and differing units, the rates of survival and mortality related to road traffic accidents were imbalanced, so the data was corrected and standardized before the classification models' performances were compared. Using the importance analysis, the main diagnosis, the type of injury, the site of the injury, the type of injury, the operation status, the type of accident, the role at the time of the accident, and the sex were selected as the analysis factors. The biggest contributing factor was the role in the accident, which is the driver, and the major sites of the injuries were head injuries and deep injuries. Using selected factors, comparisons of the classification performance of each model indicated RBF-SVM and RF models were superior to the others. Of the SVM models, the RBF kernel model was superior to the linear kernel model; it can be inferred that the performance of the high-dimensional transformed RBF model is superior when the dimension is complex because of the use of multiple variables. The findings suggest there are limitations to analyses involving imbalanced, multidimensional original data, such as data on road traffic mortality. Thus, analyses must be performed after imbalances are corrected.
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http://dx.doi.org/10.3390/ijerph18115604DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8197414PMC
May 2021

A Knitted Sensing Glove for Human Hand Postures Pattern Recognition.

Sensors (Basel) 2021 Feb 15;21(4). Epub 2021 Feb 15.

Department of Electrical and Electronic Engineering, Hanyang University, Ansan 15588, Korea.

In recent years, flexible sensors for data gloves have been developed that aim to achieve excellent wearability, but they are associated with difficulties due to the complicated manufacturing and embedding into the glove. This study proposes a knitted glove integrated with strain sensors for pattern recognition of hand postures. The proposed sensing glove is fabricated at all once by a knitting technique without sewing and bonding, which is composed of strain sensors knitted with conductive yarn and a glove body with non-conductive yarn. To verify the performance of the developed glove, electrical resistance variations were measured according to the flexed angle and speed. These data showed different values depending on the speed or angle of movements. We carried out experiments on hand postures pattern recognition for the practicability verification of the knitted sensing glove. For this purpose, 10 able-bodied subjects participated in the recognition experiments on 10 target hand postures. The average classification accuracy of 10 subjects reached 94.17% when their own data were used. The accuracy of up to 97.1% was achieved in the case of grasp posture among 10 target postures. When all mixed data from 10 subjects were utilized for pattern recognition, the average classification expressed by the confusion matrix arrived at 89.5%. Therefore, the comprehensive experimental results demonstrated the effectiveness of the knitted sensing gloves. In addition, it is expected to reduce the cost through a simple manufacturing process of the knitted sensing glove.
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http://dx.doi.org/10.3390/s21041364DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7919032PMC
February 2021

Enhanced Cancer DNA Vaccine Direct Transfection to Host Dendritic Cells Recruited in Injectable Scaffolds.

ACS Nano 2020 09 24;14(9):11623-11636. Epub 2020 Aug 24.

School of Chemical Engineering, Sungkyunkwan University (SKKU), Suwon 16419, Republic of Korea.

Deoxyribonucleic acid (DNA) vaccines are a promising cancer immunotherapy approach. However, effective delivery of DNA to antigen-presenting cells (.., dendritic cells (DCs)) for the induction of an adaptive immune response is limited. Conventional DNA delivery intramuscular, intradermal, and subcutaneous injection by hypodermal needles shows a low potency and immunogenicity. Here, we propose the enhanced cancer DNA vaccine by direct transfection to the high number of DCs recruited into the chemoattractant-loaded injectable mesoporous silica microrods (MSRs). Subcutaneous administration of the MSRs mixed with tumor-antigen coding DNA polyplexes resulted in DC recruitment in the macroporous space of the scaffold formed by the spontaneous assembly of high-aspect-ratio MSRs, thereby allowing for enhanced cellular uptake of antigen-coded DNA by host DCs. The MSR scaffolds delivering the DNA vaccine trigger a more robust DC activation, antigen-specific CD8 T cell response, and Th1 immune response compared to the bolus DNA vaccine. Additionally, the immunological memory can be induced with a single administration of the vaccine. The combination of the vaccination and antiprogrammed cell death-1 antibody significantly eliminates established lung metastasis. These results indicate that MSRs serve as a powerful platform for DNA vaccine delivery to DCs for effective cancer immunotherapy.
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http://dx.doi.org/10.1021/acsnano.0c04188DOI Listing
September 2020

Decision and Event-Based Fixed-Time Consensus Control for Electromagnetic Source Localization.

IEEE Trans Cybern 2020 Jul 29;PP. Epub 2020 Jul 29.

This article deals with the problem of electromagnetic source localization (ESL). An evolutionary particle filter, which is first used to make a decision on the positions of electromagnetic sources, has two characteristics. One characteristic is that the number of particles can be significantly reduced while the other characteristic is that the particle diversity can be well improved. On the basis of the estimated positions of electromagnetic sources, the position and velocity of the virtual leader can be determined. Then, an event-based fixed-time consensus control approach is proposed such that the positions and velocities of robots reach consensus with the virtual leader over a fixed-time interval while saving resource consumption by reducing the communication frequencies and updating times of control inputs. Finally, simulation and experimental results show the effectiveness of the proposed decision and event-based fixed-time consensus control approach for ESL.
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http://dx.doi.org/10.1109/TCYB.2020.3005964DOI Listing
July 2020

Extension Mechanism of the Proximal Interphalangeal Joint of the Human Phalanx: A Cadaveric Biomechanical Study.

Biomed Res Int 2020 20;2020:7585976. Epub 2020 Jun 20.

Department of Orthopaedic Surgery, Dongtan Sacred Heart Hospital, Hallym University College of Medicine, Hwaseong, Republic of Korea.

Our purpose was to compare the contributions of these two systems to assess PIP joint extension in fresh cadaver models. Nine middle fingers of fresh cadavers were used. The PIP joint angle was measured while an extension load was applied on the extensor tendons. Specimens on which extension load was applied on the extrinsic extensors were classified as the extrinsic group, and those on which extension load was applied on the intrinsic extensors were classified as the intrinsic group. Linear regression analyses were performed to obtain regression equation and the extension load-PIP joint angle curve. The mean of slope of the curve was compared between the two groups using paired -test. The same experiments were done for the metacarpophalangeal (MP) joint in 0° and 60° flexion to evaluate the effect of MP joint flexion on PIP joint extension. The mean slope of the extension load-PIP joint angle curve of the extrinsic group was significantly greater than that of the intrinsic group. With the MP joint in 0° flexion, the mean slope of the extrinsic and intrinsic groups was -0.148 and -0.117, respectively (greater absolute value means greater slope, = 0.01). With the MP joint in 60° flexion, the mean slopes were -0.147 and -0.104, respectively ( = 0.015). The contribution of the intrinsic extensor for PIP joint extension shows decreasing trends with MP joint flexion. The extrinsic extensors have greater contribution for PIP joint extension compared with the intrinsic extensors.
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http://dx.doi.org/10.1155/2020/7585976DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7327553PMC
April 2021

Robust Control for the Detection Threshold of CFAR Process in Cluttered Environments.

Sensors (Basel) 2020 Jul 13;20(14). Epub 2020 Jul 13.

Department of Electronic Systems Engineering, Hanyang University, Ansan 15588, Korea.

The constant false alarm rate (CFAR) process is essential for target detection in radar systems. Although the detection performance of the CFAR process is normally guaranteed in noise-limited environments, it may be dramatically degraded in clutter-limited environments since the probabilistic characteristics for clutter are unknown. Therefore, sophisticated CFAR processes that suppress the effect of clutter can be used in actual applications. However, these methods have the fundamental limitation of detection performance because there is no feedback structure in terms of the probability of false alarm for determining the detection threshold. This paper presents a robust control scheme for adjusting the detection threshold of the CFAR process while estimating the clutter measurement density (CMD) that uses only the measurement sets over a finite time interval in order to adapt to time-varying cluttered environments, and the probability of target existence with finite measurement sets required for estimating CMD is derived. The improved performance of the proposed method was verified by simulation experiments for heterogeneous situations.
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http://dx.doi.org/10.3390/s20143904DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7412031PMC
July 2020

Shot-Noise-Limited Two-Color Stimulated Raman Scattering Microscopy with a Balanced Detection Scheme.

J Phys Chem B 2020 04 24;124(13):2591-2599. Epub 2020 Mar 24.

Center for Molecular Spectroscopy and Dynamics, Institute for Basic Science (IBS), Seoul 02841, Republic of Korea.

Stimulated Raman scattering (SRS) microscopy has been considered a useful technique for investigating chemical components by selectively targeting the vibration mode of chemical structures. Its practical application to the observation of molecular structures and dynamics in complicated biological environments requires broad spectral coverage with both high resolution and a high signal-to-noise ratio. Here, we demonstrate a two-color SRS microscopy employing a balanced detection scheme and a spectral focusing method. Two different SRS signals are generated with pump and Stokes laser pulse pairs in perpendicular polarization, where each of them acts as an intensity reference for the other, significantly reducing the background noise level close to the shot-noise limit even with a fiber-based femtosecond laser system. The high spectral resolution comparable to that of spontaneous Raman scattering spectroscopy is achieved with the spectral focusing method. The two-color SRS images are obtained for a mixture of polymer beads and for the distributions of lipids and proteins in U2OS cells.
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http://dx.doi.org/10.1021/acs.jpcb.0c01065DOI Listing
April 2020

Fabric Vest Socket with Embroidered Electrodes for Control of Myoelectric Prosthesis.

Sensors (Basel) 2020 Feb 21;20(4). Epub 2020 Feb 21.

Department of Electrical and Electronic Engineering, Hanyang University, Ansan 15588, Korea.

Myoelectric prostheses assist users to live their daily lives. However, the majority of users are primarily confined to forearm amputees because the surface electromyography (sEMG) that understands the motion intents should be acquired from a residual limb for control of the myoelectric prosthesis. This study proposes a novel fabric vest socket that includes embroidered electrodes suitable for a high-level upper amputee, especially for shoulder disarticulation. The fabric vest socket consists of rigid support and a fabric vest with embroidered electrodes. Several experiments were conducted to verify the practicality of the developed vest socket with embroidered electrodes. The sEMG signals were measured using commercial Ag/AgCl electrodes for a comparison to verify the performance of the embroidered electrodes in terms of signal amplitudes, the skin-electrode impedance, and signal-to-noise ratio (SNR). These results showed that the embroidered electrodes were as effective as the commercial electrodes. Then, posture classification was carried out by able-bodied subjects for the usability of the developed vest socket. The average classification accuracy for each subject reached 97.92%, and for all the subjects it was 93.2%. In other words, the fabric vest socket with the embroidered electrodes could measure sEMG signals with high accuracy. Therefore, it is expected that it can be readily worn by high-level amputees to control their myoelectric prostheses, as well as it is cost effective for fabrication as compared with the traditional socket.
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http://dx.doi.org/10.3390/s20041196DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7071049PMC
February 2020

Injectable dual-scale mesoporous silica cancer vaccine enabling efficient delivery of antigen/adjuvant-loaded nanoparticles to dendritic cells recruited in local macroporous scaffold.

Biomaterials 2020 05 10;239:119859. Epub 2020 Feb 10.

School of Chemical Engineering, Sungkyunkwan University (SKKU), Suwon, 16419, Republic of Korea; Department of Health Sciences and Technology, Samsung Advanced Institute for Health Science & Technology (SAIHST), Sungkyunkwan University (SKKU), Suwon, 16419, Republic of Korea; Biomedical Institute for Convergence at SKKU (BICS), Sungkyunkwan University (SKKU), Suwon, 16419, Republic of Korea; Institute of Quantum Biophysics (IQB), Sungkyunkwan University (SKKU), Suwon, 16419, Republic of Korea. Electronic address:

Despite the potential of nanoparticle-based vaccines, their therapeutic efficacy for cancer immunotherapy is limited. To elicit robust antigen-specific adaptive immune responses, antigen-loaded nanoparticles are employed for transport into host dendritic cells (DCs); however, only a minority of the nanoparticles can be engulfed by host DCs. Herein, an injectable dual-scale mesoporous silica vaccine consisting of mesoporous silica microrods (MSRs) coupled with mesoporous silica nanoparticles (MSNs) is introduced. The MSRs form a three-dimensional macroporous scaffold after injection, and the subsequent release of DC-recruiting chemokine loaded in the mesopores of MSRs leads to the recruitment of numerous DCs into the scaffold. Subsequently, MSNs co-loaded with an antigen and Toll-like receptor 9 agonist, which exist in interparticle space of the MSR scaffold, are internalized by the recruited DCs, leading to the generation of antigen-presenting activated DCs. Strikingly, the MSR-MSN dual-scale vaccine generates a significantly larger number of antigen-specific T cells and inhibits melanoma growth to a greater extent compared with a single MSR or MSN vaccine. Moreover, the dual-scale vaccine is synergized with an immune checkpoint inhibitor to inhibit tumor growth in tumor-bearing mice. The findings suggest that the MSR is a novel platform for delivering nanoparticle vaccines for the enhancement of cancer immunotherapy.
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http://dx.doi.org/10.1016/j.biomaterials.2020.119859DOI Listing
May 2020

Sulforaphane mitigates mast cell-mediated allergic inflammatory reactions in simulation and models.

Immunopharmacol Immunotoxicol 2020 Apr 10;42(2):74-83. Epub 2020 Feb 10.

Department of Food Science and Technology, Hoseo University, Asan, Korea.

Sulforaphane, a major ingredient isolated from var. (broccoli), is known to exhibit anti-inflammatory, anti-cancer, and anti-diabetic effects. In this study, we employed an model of phorbol 12-myristate 13-acetate and a23187 (PMACI)-stimulated human mast cells (HMC-1 cells) to investigate the anti-allergic inflammatory effects and mechanisms of sulforaphane and var. extracts. Cytokine levels were measured by ELISA and quantitative real-time-PCR methods. Caspase-1 activity was determined by caspase-1 assay. Binding mode of sulforaphane within caspase-1 was determined by molecular docking simulation. Protein expression was determined by Western blotting. Water extract of var. (WE) significantly reduced thymic stromal lymphopoietin (TSLP) secretion and caspase-1 activity on activated HMC-1 cells. In the molecular docking simulation and caspase-1 assays, sulforaphane regulated caspase-1 activity by docking with the identical binding site of caspase-1. Sulforaphane significantly inhibited the levels of inflammatory mediators including TSLP, tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, and IL-8 in a dose-dependent manner. Immunoblotting experiments revealed that sulforaphane and WE reduced translocation of NF-κBp65 into the nucleus and phosphorylation of IκBα in the cytosol. Furthermore, phosphorylation of mitogen-activated protein kinases (MAPK) was down-regulated by treatment with sulforaphane or WE. Our findings suggest that sulforaphane and WE have anti-allergic inflammatory effects by intercepting caspase-1/NF-κB/MAPKs signaling pathways.
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http://dx.doi.org/10.1080/08923973.2020.1724141DOI Listing
April 2020

Comparing Logistic Regression Models with Alternative Machine Learning Methods to Predict the Risk of Drug Intoxication Mortality.

Int J Environ Res Public Health 2020 01 31;17(3). Epub 2020 Jan 31.

Department of Health Administration, Dankook University, Cheonan 31116, Korea.

(1) Medical research has shown an increasing interest in machine learning, permitting massive multivariate data analysis. Thus, we developed drug intoxication mortality prediction models, and compared machine learning models and traditional logistic regression. (2) Categorized as drug intoxication, 8,937 samples were extracted from the Korea Centers for Disease Control and Prevention (2008-2017). We trained, validated, and tested each model through data and compared their performance using three measures: Brier score, calibration slope, and calibration-in-the-large. (3) A chi-square test demonstrated that mortality risk statistically significantly differed according to severity, intent, toxic substance, age, and sex. The multilayer perceptron model (MLP) had the highest area under the curve (AUC), and lowest Brier score in training and validation phases, while the logistic regression model (LR) showed the highest AUC (0.827) and lowest Brier score (0.0307) in the testing phase. MLP also had the second-highest AUC (0.816) and second-lowest Brier score (0.003258) in the testing phase, demonstrating better performance than the decision-making tree model. (4) Given the complexity of choosing tuning parameters, LR proved competitive when using medical datasets, which require strict accuracy.
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http://dx.doi.org/10.3390/ijerph17030897DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7037603PMC
January 2020

RACK1 interaction with c-Src is essential for osteoclast function.

Exp Mol Med 2019 07 29;51(7):1-9. Epub 2019 Jul 29.

Department of Life Science, Ewha Womans University, Seoul, 03760, Korea.

The scaffolding protein receptor for activated C-kinase 1 (RACK1) mediates receptor activator of nuclear factor κΒ ligand (RANKL)-dependent activation of p38 MAPK in osteoclast precursors; however, the role of RACK1 in mature osteoclasts is unclear. The aim of our study was to identify the interaction between RACK1 and c-Src that is critical for osteoclast function. A RACK1 mutant protein (mutations of tyrosine 228 and 246 residues to phenylalanine; RACK1 Y228F/Y246F) did not interact with c-Src. The mutant retained its ability to differentiate into osteoclasts; however, the integrity of the RANKL-mediated cytoskeleton, bone resorption activity, and phosphorylation of c-Src was significantly decreased. Importantly, lysine 152 (K152) within the Src homology 2 (SH2) domain of c-Src is involved in RACK1 binding. The c-Src K152R mutant (mutation of lysine 152 into arginine) impaired the resorption of bone by osteoclasts. These findings not only clarify the role of the RACK1-c-Src axis as a key regulator of osteoclast function but will also help to develop new antiresorption therapies to prevent bone loss-related diseases.
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http://dx.doi.org/10.1038/s12276-019-0285-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6802652PMC
July 2019

Hierarchically Porous Composite Scaffold Composed of SBA-15 Microrods and Reduced Graphene Oxide Functionalized with Cyclodextrin for Water Purification.

ACS Appl Mater Interfaces 2019 May 23;11(17):15764-15772. Epub 2019 Apr 23.

Large-scale decontamination of bisphenol A (BPA) from wastewater under field conditions is an urgent need because of the harmful toxic effects of BPA on living organisms. In this study, we report the fabrication of a three-dimensional (3D) hierarchically porous composite scaffold composed of mesoporous SBA-15 silica microrods and reduced graphene oxide (rGO-CD) functionalized with β-cyclodextrin (CD) and its application for BPA separation from contaminated water. The macroporous structure was achieved by sacrificial salt leaching, and the mesoporous structure was derived from the interparticle pores between compressed SBA-15 particles and intrinsic mesopores in SBA-15. The 3D hierarchical macroporous and mesoporous architecture of the scaffold enhances mass transport without any external forces, and the rGO-CD component provides good capture sites for BPA in solution via inclusion complexation between CD and BPA. The inorganic SBA-15 component of the scaffold also allows long-term operation of filters by increasing the mechanical strength of the scaffold. The hierarchically porous SBA-15/rGO-CD composite scaffold could separate BPA from contaminated water significantly better than the scaffold without rGO-CD in both batch and filter systems. Our study indicates that the functional hierarchically porous composite scaffold can be a potential material in wastewater treatment technology.
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http://dx.doi.org/10.1021/acsami.9b01845DOI Listing
May 2019

Polyaspartamide Functionalized Catechol-Based Hydrogels Embedded with Silver Nanoparticles for Antimicrobial Properties.

Polymers (Basel) 2018 Oct 25;10(11). Epub 2018 Oct 25.

Department of Chemistry, University of Fribourg, Chemin du Musée, 9, 1700 Fribourg, Switzerland.

In this study, polyaspartamide-based hydrogels were synthesized by boron-catechol coordination followed by incorporation of AgNPs into the materials. Free catechol moieties were exploited to produce AgNPs. TEM analyses displayed AgNPs of less than 20 nm in diameter and with minimum aggregation, attesting the role of hydrogels to act as an efficient template for the production of dispersed particles. XRD analyses confirmed the mean particle size using the Scherrer equation. Release kinetic studies were performed in DMEM medium, showing a slow release over a long time-period. Finally, the MIC and MBC were determined, demonstrating a bacteriostatic and bactericidal effect against Gram-positive and Gram-negative .
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http://dx.doi.org/10.3390/polym10111188DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6290624PMC
October 2018

Solubility Enhancement of Atrazine by Complexation with Cyclosophoraose Isolated from biovar TA-1.

Polymers (Basel) 2019 Mar 12;11(3). Epub 2019 Mar 12.

Department of Systems Biotechnology & Dept. of Bioscience and Biotechnology, Microbial Carbohydrate Resource Bank (MCRB), Center for Biotechnology Research in UBITA (CBRU), Konkuk University, Seoul 05029, Korea.

biovar TA-1, a kind of soil bacteria, produces cyclosophoraoses (Cys). Cyclosophoraoses contain various ring sizes with degrees of polymerization ranging from 17 to 23. Atrazine is a hardly-soluble herbicide that contaminates soil and drinking water, and remains in soil for a long time. To remove this insoluble contaminant from aqueous solutions, we have enhanced the solubility of atrazine by complexation with Cys. The complex formation of Cys and atrazine was confirmed using ¹H nuclear magnetic resonance (NMR), Fourier transform infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC), field emission scanning electron microscopy (FE-SEM), rotating frame nuclear overhauser spectroscopy (ROESY), and molecular modeling studies. The aqueous solubility of atrazine was enhanced 3.69-fold according to the added concentrations (20 mM) of Cys, compared to the 1.78-fold enhancements by β-cyclodextrin (β-CD). Cyclosophoraoses as an excellent solubility enhancer with long glucose chains that can effectively capture insoluble materials showed a potential application of microbial polysaccharides in the removal of hazardous hardly-soluble materials from aqueous solutions in the fields of biological and environmental industry.
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http://dx.doi.org/10.3390/polym11030474DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6473739PMC
March 2019

A 3D Macroporous Alginate Graphene Scaffold with an Extremely Slow Release of a Loaded Cargo for In Situ Long-Term Activation of Dendritic Cells.

Adv Healthc Mater 2019 03 25;8(5):e1800571. Epub 2019 Jan 25.

School of Chemical Engineering, Sungkyunkwan University (SKKU), Suwon, 16419, Republic of Korea.

Ex vivo manipulation of autologous antigen-presenting cells and their subsequent infusion back into the patient to dictate immune response is one of the promising strategies in cancer immunotherapy. Here, a 3D alginate scaffold embedded with reduced graphene oxide (rGO) is proposed as a vaccine delivery platform for in situ long-term activation of antigen-presenting dendritic cells (DCs). High surface area and hydrophobic surface of the rGO component of the scaffold provide high loading and a very slow release of a loaded antigen, danger signal, and/or chemoattractant from the scaffold. This approach offers long-term bioavailability of the loaded cargo inside the scaffold for manipulation of recruited DCs. After mice are subcutaneously vaccinated with the macroporous alginate graphene scaffold (MAGS) loaded with ovalbumin (OVA) and granulocyte-macrophage colony-stimulating factor (GM-CSF), this scaffold recruits a significantly high number of DCs, which present antigenic information via major histocompatibility complex class I for a long period. Furthermore, an MAGS loaded with OVA, GM-CSF, and CpG promotes production of activated T cells and memory T cells, leading to the suppression of OVA-expressing B16 melanoma tumor growth in a prophylactic vaccination experiment. This study indicates that an MAGS can be a strong candidate for long-term programming and modulating immune cells in vivo.
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http://dx.doi.org/10.1002/adhm.201800571DOI Listing
March 2019

Mesoporous Silica as a Versatile Platform for Cancer Immunotherapy.

Adv Mater 2019 Aug 12;31(34):e1803953. Epub 2018 Nov 12.

School of Chemical Engineering, Sungkyunkwan University (SKKU), Suwon, 16419, Republic of Korea.

Immunotherapy has been recognized for decades as a promising therapeutic method for cancer treatment. To enhance host immune responses against cancer, antigen-presenting cells (APCs; e.g., dendritic cells) or T cells are educated using immunomodulatory agents including tumor-associated antigens and adjuvants, and manipulated to induce a cascading adaptive immune response targeting tumor cells. Mesoporous silica materials are promising candidates to improve cancer immunotherapy based on their attractive properties that include high porosity, high biocompatibility, facile surface modification, and self-adjuvanticity. Here, the recent progress on mesoporous-silica-based immunotherapies based on two material forms is summarized: 1) mesoporous silica nanoparticles (MSNs), which can be internalized into APCs, and 2) micrometer-sized mesoporous silica rods (MSRs) that can form a 3D space to recruit APCs. Subcutaneously injected MSN-based cancer vaccines can be taken up by peripheral APCs or by APCs in lymphoid organs to educate the immune system against cancer cells. MSR cancer vaccines can recruit immune cells into the MSR scaffold to induce cancer-specific immunity. Both vaccine systems successfully stimulate the adaptive immune response to eradicate cancer in vivo. Thus, mesoporous silica has potential value as a material platform for the treatment of cancer or infectious diseases.
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http://dx.doi.org/10.1002/adma.201803953DOI Listing
August 2019

Experiments of three identical huts with shape-stabilized phase change materials and simulation of detached house in Japanese climate classification.

Data Brief 2018 Dec 2;21:403-406. Epub 2018 Oct 2.

Department of Architecture, Graduate School of Engineering, The University of Tokyo, Japan.

The data in this article are the experiment and simulation results of three identical huts were examined using by using varying shape-stabilized PCMs (SSPCMs) sheet levels in winter of Chiba prefecture where Japanese temperate climate. A shape-stabilized phase-change material (SSPCM) established the melting- and solidification-temperature ranges at 19-26 °C was installed on the floor, walls, and ceiling of various buildings, and its effects on indoor room temperature stabilization and heating load reduction were examined using experiments and simulations. The PCM model was developed based on the specific heat capacity measured using a thermostatic chamber and simulations results were obtained using EnergyPlus. The validity of the PCM model was examined by comparing the simulation and experimental results. The model was then examined to determine the applicability of PCM to the various climates in Japan through annual heating load simulations. The target buildings were classified as Type A (no PCM, reference), Type B (only the floor contained PCM), and Type C (the floor, walls, and ceiling contained PCM) using a standard Japanese house. Types B and C had the same amount of PCM. The simulation was run for 21 cases, with one being run for each type of building in seven Japanese climates.
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http://dx.doi.org/10.1016/j.dib.2018.09.095DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6198124PMC
December 2018

Data on experiments result of three identical huts with shape-stabilized phase change materials in Japanese temperate climate.

Data Brief 2018 Apr 14;17:897-899. Epub 2018 Feb 14.

JXTG Nippon Oil & Energy Corporation, Japan.

The data in this article are the experimental results of three identical huts (Hut A, B and C), which were examined by using varying shape-stabilized PCMs (SSPCMs) sheet levels under natural and heating conditions in winter of Chiba prefecture where Japanese temperate climate. The SSPCMs sheet established the melting and solidification-temperature ranged at 19-26 °C were used. In Hut A, no SSPCM sheets were applied; in Hut B, four layers of SSPCM sheets were applied to the floor; in Hut C, one layer of SSPCM was applied to the floor, walls, and ceilings. The data provide information on the application of SSPCM sheets to improve indoor stabilization and the heating load reduction effects.
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http://dx.doi.org/10.1016/j.dib.2018.01.088DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5988508PMC
April 2018

A facile approach to enhance antigen response for personalized cancer vaccination.

Nat Mater 2018 06 5;17(6):528-534. Epub 2018 Mar 5.

John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA.

Existing strategies to enhance peptide immunogenicity for cancer vaccination generally require direct peptide alteration, which, beyond practical issues, may impact peptide presentation and result in vaccine variability. Here, we report a simple adsorption approach using polyethyleneimine (PEI) in a mesoporous silica microrod (MSR) vaccine to enhance antigen immunogenicity. The MSR-PEI vaccine significantly enhanced host dendritic cell activation and T-cell response over the existing MSR vaccine and bolus vaccine formulations. Impressively, a single injection of the MSR-PEI vaccine using an E7 peptide completely eradicated large, established TC-1 tumours in about 80% of mice and generated immunological memory. When immunized with a pool of B16F10 or CT26 neoantigens, the MSR-PEI vaccine eradicated established lung metastases, controlled tumour growth and synergized with anti-CTLA4 therapy. Our findings from three independent tumour models suggest that the MSR-PEI vaccine approach may serve as a facile and powerful multi-antigen platform to enable robust personalized cancer vaccination.
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http://dx.doi.org/10.1038/s41563-018-0028-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5970019PMC
June 2018

Carboxymethyl cyclosophoraoses as a flexible pH-responsive solubilizer for pindolol.

Carbohydr Polym 2017 Nov 9;175:493-501. Epub 2017 Aug 9.

Department of Bioscience and Biotechnology, Microbial Carbohydrate Resource Bank (MCRB), Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul 05029, South Korea. Electronic address:

In the present study, cyclosophoraoses (CyS) (β-1,2 linked cyclic glucans, with glucopyranose units ranging from 17 to 23) isolated from Rhizobium leguminosarum biovar viciae VF-39 were modified with carboxymethyl (CM) groups, and the pH-sensitive complexation of CM CyS with pindolol was investigated. The solubility of pindolol increased 32-fold by its complexation with 5mM CM CyS at pH 10, whereas it shows no significant change at pH 3. Pindolol, a β-adrenergic blocking agent, has a hydrophobic nature at non-ionized state, and CM CyS could solubilize efficiently pindolol in a high alkaline solution. The carboxymethylation of flexible CyS allows them to present a more suitable cavity for the hydrophobic pindolol at pH 10, which is differentiated from CM β-cyclodextrin (β-CD). It can be interpreted as that the anionic repulsion effectively modulates the flexible and distorted conformation of CyS rather than rigid annular shape of β-CD. Resultingly, the highly solubilized CM CyS/pindolol complex was characterized by UV-vis, T1 relaxation, ROESY, DOSY NMR spectroscopy, FT-IR spectroscopy, SEM, and molecular modeling studies. The antioxidant activity of pindolol was also improved 260% in the complex compared to free pindolol. The use of flexible host molecules with pH-responsive substituents would be applied in the development of smart systems for sensing or in biomedical fields.
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http://dx.doi.org/10.1016/j.carbpol.2017.08.026DOI Listing
November 2017

Colloidal Mesoporous Silica Nanoparticles as Strong Adhesives for Hydrogels and Biological Tissues.

ACS Appl Mater Interfaces 2017 Sep 5;9(37):31469-31477. Epub 2017 Sep 5.

School of Chemical Engineering, ‡Department of Health Sciences and Technology, Samsung Advanced Institute for Health Science & Technology (SAIHST), and §Biomedical Institute for Convergence at SKKU (BICS), Sungkyunkwan University , Suwon 16419, Republic of Korea.

Sub-100 nm colloidal mesoporous silica (CMS) nanoparticles are evaluated as an adhesive for hydrogels or biological tissues. Because the adhesion energy is proportional to the surface area of the nanoparticles, the CMS nanoparticles could provide a stronger adhesion between two hydrogels than the nonporous silica nanoparticles. In the case of 50 nm CMS nanoparticles with a pore diameter of 6.45 nm, the maximum adhesion energy was approximately 35.0 J/m at 3.0 wt %, whereas the 10 wt % nonporous silica nanoparticle solution showed only 7.0 J/m. Moreover, the CMS nanoparticle solution had an adhesion energy of 22.0 J/m at 0.3 wt %, which was 11 times higher than that of the nonporous nanoparticles at the same concentration. Moreover, these CMS nanoparticles are demonstrated for adhering incised skin tissues of mouse, resulting in rapid healing even at a lower nanoparticle concentration. Finally, the CMS nanoparticles had added benefit of quick degradation in biological media because of their porous structure, which may prevent unwanted accumulation in tissues.
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http://dx.doi.org/10.1021/acsami.7b09083DOI Listing
September 2017

Dynamic elasticity measurement for prosthetic socket design.

IEEE Int Conf Rehabil Robot 2017 07;2017:1281-1286

The paper proposes a novel apparatus to measure the dynamic elasticity of human limb in order to help the design and fabrication of the personalized prosthetic socket. To take measurements of the dynamic elasticity, the desired force generated as an exponential chirp signal in which the frequency increases and amplitude is maintained according to time progress is applied to human limb and then the skin deformation is recorded, ultimately, to obtain the frequency response of its elasticity. It is referred to as a Dynamic Elasticity Measurement Apparatus (DEMA) in the paper. It has three core components such as linear motor to provide the desired force, loadcell to implement the force feedback control, and potentiometer to record the skin deformation. After measuring the force/deformation and calculating the dynamic elasticity of the limb, it is visualized as 3D color map model of the limb so that the entire dynamic elasticity can be shown at a glance according to the locations and frequencies. For the visualization, the dynamic elasticities measured at specific locations and frequencies are embodied using the color map into 3D limb model acquired by using 3D scanner. To demonstrate the effectiveness, the visualized dynamic elasticities are suggested as outcome of the proposed system, although we do not have any opportunity to apply the proposed system to the amputees. Ultimately, it is expected that the proposed system can be utilized to design and fabricate the personalized prosthetic socket in order for releasing the wearing pain caused by the conventional prosthetic socket.
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http://dx.doi.org/10.1109/ICORR.2017.8009425DOI Listing
July 2017

Human mimetic forearm mechanism towards bionic arm.

IEEE Int Conf Rehabil Robot 2017 07;2017:1171-1176

The paper presents a mechanical forearm mechanism to extend the pronation and supination (P/S) movement of the trans-radial amputee when he/she is able to conduct the P/S motion partially with his/her remaining forearm. The P/S motions of the existing prostheses and robotic arms developed till now are completely different from those of the human. When we are to develop the robotic prostheses for the amputees, two important issues should be considered such as cosmetic issue to look like normal arm and motion harmony issue between robotic prosthesis and the amputated living arm. Most prostheses do not realize the human-like P/S motion, but the simple rotational motion at the wrist by using the electric motor. In this paper, the well-known spatial four-bar mechanism is adopted in order to mimic human P/S motion as if the person does, because it is one of the best candidates to describe actual human forearm movement. To obtain the design parameters of the mechanism, first, 3D data of the amputated arm as well as the opposite side non-amputated arm are captured by using MRI (Magnetic Resonance Imaging) and 3D scanner. The design parameters such as link lengths, joint locations, and volumetric shape are determined from the measured data. Second, mathematical analysis is performed to simulate one degree-of-freedom P/S motion realized from the spatial four-bar mechanism, and the simulation results are suggested to confirm whether or not it acts like the relative movement between human ulnar and radius bones. Finally the effectiveness of the proposed mechanism is verified through two ADL (activities of daily living) tests.
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http://dx.doi.org/10.1109/ICORR.2017.8009408DOI Listing
July 2017

Bioadhesive Nanoaggregates Based on Polyaspartamide-g-C18/DOPA for Wound Healing.

Biomacromolecules 2017 Aug 5;18(8):2402-2409. Epub 2017 Jul 5.

School of Chemical Engineering, Sungkyunkwan University , Suwon, Kyunggi 16419, Republic of Korea.

Biocompatible adhesive nanoaggregates were synthesized based on polyaspartamide copolymers grafted with octadecylamine (C18) and 3,4-dihydroxyphenylalanine (DOPA), and their adhesive properties were investigated with regard to wound healing. The chemical structure and morphology of the synthesized polyaspartamide-g-C18/DOPA nanoaggregates were analyzed using H-nuclear magnetic resonance spectroscopy (H NMR), dynamic light scattering (DLS), and transmission electron microscope (TEM). The in vitro adhesive energy was up to 31.04 J m for poly(dimethylacrylamide) gel substrates and 0.1209 MPa for mouse skin, and the in vivo wound breaking strength after 48 h was 1.8291 MPa for C57BL/6 mouse. The MTT assay demonstrated that the synthesized polymeric nanoaggregates were nontoxic. The polyaspartamide-g-C18/DOPA nanoaggregates were in vivo tested to mouse model and demonstrated successful skin adhesion, as the mouse skin was perfectly cured in their dermis within 6 d. As this material has biocompatibility and enough adhesive strength for wound closure, it is expected to be applied as a new type of bioadhesive agent in the human body.
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http://dx.doi.org/10.1021/acs.biomac.7b00584DOI Listing
August 2017

Solubility and bioavailability enhancement of ciprofloxacin by induced oval-shaped mono-6-deoxy-6-aminoethylamino-β-cyclodextrin.

Carbohydr Polym 2017 May 22;163:118-128. Epub 2017 Jan 22.

Department of Systems Biotechnology, Microbial Carbohydrate Resource Bank (MCRB) & Center for Biotechnology Research in UBITA (CBRU), Konkuk University, Seoul, Republic of Korea. Electronic address:

Ciprofloxacin is a broad-spectrum fluoroquinolone antibiotic used to treat bacterial infections; however, its limited aqueous solubility inhibits its broader clinical uses. This study investigated the complexation effect of mono-6-deoxy-6-aminoethylamino-β-cyclodextrin on the aqueous solubility and bioavailability of ciprofloxacin. During complexation, the oval-shaped cavity induced by mono-aminoethylamine substitution on the primary rim of β-cyclodextrin, was considered to be a key factor according to NMR spectroscopy and molecular modeling studies. The ciprofloxacin with mono-6-deoxy-6-aminoethylamino-β-cyclodextrin complex was characterized using FE-SEM, DSC, FT-IR, T1 relaxation, 2D NOESY, and DOSY NMR spectroscopy and molecular modeling studies. The solubility property of ciprofloxacin complexed with mono-6-deoxy-6-aminoethylamino-β-cyclodextrin was enhanced by seven-fold compared to that of pure ciprofloxacin. Furthermore antibacterial activity of that complex against methicillin-resistant Staphylococcus aureus was enhanced and it clearly showed the growth inhibition. The mono-6-deoxy-6-aminoethylamino-β-cyclodextrin has the potential to be utilized for other oblong guest molecules besides ciprofloxacin based on the novel induced elliptical cavity.
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http://dx.doi.org/10.1016/j.carbpol.2017.01.073DOI Listing
May 2017

Cordycepin diminishes thymic stromal lymphopoietin-induced interleukin-13 production.

Eur J Pharmacol 2017 May 20;802:1-6. Epub 2017 Feb 20.

Department of Food Science & Technology, Hoseo University, 20, Hoseo-ro 79beon-gil, Baebang-eup, Asan, Chungcheongnam-do 31499, Republic of Korea. Electronic address:

Atopic dermatitis (AD) is known to aggravate by thymic stromal lymphopoietin (TSLP) and TSLP is also known to up-regulate mast cell proliferation via production of interleukin (IL)-13. Thus, we investigated whether cordycepin could regulate mast cell proliferation induced by TSLP in human mast cell line, HMC-1 cell. Cordycepin significantly diminished the production and mRNA of IL-13 through the down-regulation of phosphorylated-signal transducer and activation of transcription 6 in the TSLP-stimulated HMC-1 cells. Cordycepin also significantly diminished the cell proliferation via down-regulating MDM2 and Bcl2 levels and up-regulating p53, caspase-3, and cleaved poly ADP-ribose polymerase levels in the TSLP-stimulated HMC-1 cells. Moreover, cordycepin significantly diminished the production of IL-6, tumor necrosis factor-α, and IL-1β in the TSLP-stimulated HMC-1 cells. In conclusion, our study shows that cordycepin has potential effect for the treatment of allergic inflammatory diseases through the blockade of IL-13 and MDM2 exacerbated by TSLP.
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http://dx.doi.org/10.1016/j.ejphar.2017.02.033DOI Listing
May 2017

Mechanically Enhanced Hierarchically Porous Scaffold Composed of Mesoporous Silica for Host Immune Cell Recruitment.

Adv Healthc Mater 2017 Apr 7;6(8). Epub 2017 Feb 7.

School of Chemical Engineering, Sungkyunkwan University (SKKU), Suwon, 16419, Republic of Korea.

Hierarchically porous materials have been of interest in many diverse fields, including catalysis, separations, and tissue engineering, because the hierarchical porosity of the materials contributes to improvements in mechanical properties, transport properties, and molecule selectivity. In this study, we, for the first time, introduce a new approach to fabricate hierarchical macroporous and mesoporous silica scaffolds based on a salt-leaching process using as-prepared mesoporous silica as a building block. The mechanical strength of the resulting inorganic 3D scaffold was significantly improved by controlling the interfaces of mesoporous silica particles, which allowed for high structural stability during in vivo implantation. Implantation of the scaffold loaded with pro-inflammatory cytokine in mesopores into mice successfully recruited a high number of host immune cells, including dendritic cells, into the macropores, which shows their potential use for immunomodulation.
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http://dx.doi.org/10.1002/adhm.201601160DOI Listing
April 2017

2-(4-{2-[(phenylthio)acetyl]carbonohydrazonoyl}phenoxy)acetamide as a new lead compound for management of allergic rhinitis.

Inflamm Res 2016 Dec 11;65(12):963-973. Epub 2016 Aug 11.

Department of Food Technology and Inflammatory Disease Research Center, Hoseo University, 20 Hoseo-ro, 79 Beon-gil, Baebang-eup, Asan, Chungnam, 31499, Republic of Korea.

Objective: We selected a hit compound, 2-(4-{2-[(phenylthio)acetyl]-carbonohydrazonoyl}-phenoxy)acetamide (PA), by a molecular docking simulation between 636,565 compounds and caspase-1 protein. We examined the effect of PA on allergic rhinitis (AR) animal model.

Methods: We assessed the therapeutic effects and the regulatory mechanisms of ovalbumin (OVA)-sensitized mouse model of AR.

Results: A molecular docking simulation and a kinetic assay indicated that PA regulates the caspase-1 activation through the interaction with the caspase-1 active site. In the AR animal model, PA significantly reduced the rub scoring increased by OVA. The up-regulated IgE, histamine, interleukin (IL)-1β, and thymic stromal lymphopoietin (TSLP) levels in the serum of OVA-sensitized mice were significantly decreased by the treatment with PA. Protein levels of IL-1β, IL-5, IL-6, IL-13, tumor necrosis factor-α, TSLP, cyclooxygenase-2, macrophage inflammatory protein-2, and intercellular adhesion molecule-1 were also significantly inhibited by the treatment with PA in the nasal mucosa tissues of the OVA-sensitized mice. In the PA-treated mice, the number of eosinophils and mast cells infiltrated by OVA-sensitization were also reduced. In addition, PA reduced the mast cell-derived caspase-1 activity and expression in the nasal mucosa tissues of the OVA-sensitized mice.

Conclusions: PA showed the possibility to regulate AR in OVA-induced AR models, suggesting that it has therapeutic potential for the management of AR as a lead compound.
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http://dx.doi.org/10.1007/s00011-016-0979-1DOI Listing
December 2016

Differential frontal theta activity during cognitive and motor tasks.

J Integr Neurosci 2016 Sep 22;15(3):295-303. Epub 2016 Aug 22.

† Department of English Education, Kyungpook National University, Daehak ro 80, Bukgu, Daegu 702-701, Korea.

The present study investigated psychophysiological differences between cognitive and motor tasks. Participants were 16 university students (male[Formula: see text][Formula: see text][Formula: see text]10, female[Formula: see text][Formula: see text][Formula: see text]6) aged between 24 to 31 years (mean[Formula: see text][Formula: see text][Formula: see text]27.6 years, SD[Formula: see text][Formula: see text] [Formula: see text] years). They were instructed to perform cognitive and motor tasks while their brain activity was simultaneously recorded using electroencephalography (EEG). A 3(task)[Formula: see text][Formula: see text][Formula: see text]8(area)[Formula: see text][Formula: see text][Formula: see text]4(bands) analysis of variance (ANOVA) was performed on theta, alpha and beta frequency bands. The results showed that the cognitive task resulted in a significantly higher spectral power in the theta band at frontal electrodes than did the motor task. This suggests that the frontal lobe might be engaged in problem solving, resulting in increased theta activity. However, there were no differences in alpha and beta activity between the two tasks. The present study provides psychophysiological evidence for classifying cognitive and motor tasks, which has been a controversial issue for task classifications in motor learning research.
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http://dx.doi.org/10.1142/S0219635216500199DOI Listing
September 2016