Publications by authors named "Ayoung Kim"

19 Publications

  • Page 1 of 1

Ablation of USP21 in skeletal muscle promotes oxidative fibre phenotype, inhibiting obesity and type 2 diabetes.

J Cachexia Sarcopenia Muscle 2021 Sep 15. Epub 2021 Sep 15.

College of Pharmacy and Integrated Research Institute for Drug Development, Dongguk University-Seoul, Goyang-si, Gyeonggi-Do, South Korea.

Background: Skeletal muscle as a metabolic consumer determines systemic energy homeostasis by regulating myofibre type conversion and muscle mass control. Perturbation of the skeletal muscle metabolism elevates the risk of a variety of diseases including metabolic disorders. However, the regulatory pathways and molecules are not completely understood. The discovery of relevant responsible molecules and the associated network could be an attractive strategy to overcome diseases associated with muscle problems.

Methods: An initial screening using quantitative trait locus analysis enabled us to extract a set of genes including ubiquitin-specific proteases21 (USP21) (r = 0.738; P = 0.004) as potential targets associated with fasting blood glucose content. Given tight regulation of the ubiquitination status of proteins in muscle, we focused on USP21 and generated whole-body (KO) and skeletal muscle-specific USP21 knockout (MKO) mice. Transcriptomics, proteomics, and lipidomics assays in combination with various in vivo and in vitro experiments were performed to understand the functions of USP21 and underlying mechanisms. A high-fat diet (60%)-fed mouse model and diabetic patient-derived samples were utilized to assess the effects of USP21 on energy metabolism in skeletal muscle.

Results: USP21 was highly expressed in both human and mouse skeletal muscle, and controlled skeletal muscle oxidative capacity and fuel consumption. USP21-KO or USP21-MKO significantly promoted oxidative fibre type changes (Δ36.6% or Δ47.2%), muscle mass increase (Δ13.8% to Δ22.8%), and energy expenditure through mitochondrial biogenesis, fatty acid oxidation, and UCP2/3 induction (P < 0.05 or P < 0.01). Consistently, cold exposure repressed USP21 expression in mouse skeletal muscle (Δ55.3%), whereas loss of USP21 increased thermogenesis (+1.37°C or +0.84°C; P < 0.01). Mechanistically, USP21 deubiquitinated DNA-PKcs and ACLY, which led to AMPK inhibition. Consequently, USP21 ablation diminished diet-induced obesity (WT vs. USP21-KO, Δ8.02 g, 17.1%, P < 0.01; litter vs. USP21-MKO, Δ3.48 g, 7.7%, P < 0.05) and insulin resistance. These findings were corroborated in a skeletal muscle-specific gene KO mouse model. USP21 was induced in skeletal muscle of a diabetic patient (1.94-fold), which was reciprocally changed to p-AMPK (0.30-fold).

Conclusions: The outcomes of this research provide novel information as to how USP21 in skeletal muscle contributes to systemic energy homeostasis, demonstrating USP21 as a key molecule in the regulation of myofibre type switch, muscle mass control, mitochondrial function, and heat generation and, thus, implicating the potential of this molecule and its downstream substrates network as targets for the treatment and/or prevention of muscle dysfunction and the associated metabolic diseases.
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http://dx.doi.org/10.1002/jcsm.12777DOI Listing
September 2021

Syndecan Transmembrane Domain Specifically Regulates Downstream Signaling Events of the Transmembrane Receptor Cytoplasmic Domain.

Int J Mol Sci 2021 Jul 24;22(15). Epub 2021 Jul 24.

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

Despite the known importance of the transmembrane domain (TMD) of syndecan receptors in cell adhesion and signaling, the molecular basis for syndecan TMD function remains unknown. Using in vivo invertebrate models, we found that mammalian syndecan-2 rescued both the guidance defects in hermaphrodite-specific neurons and the impaired development of the midline axons of caused by the loss of endogenous syndecan. These compensatory effects, however, were reduced significantly when syndecan-2 dimerization-defective TMD mutants were introduced. To further investigate the role of the TMD, we generated a chimera, 2eTPC, comprising the TMD of syndecan-2 linked to the cytoplasmic domain of platelet-derived growth factor receptor (PDGFR). This chimera exhibited SDS-resistant dimer formation that was lost in the corresponding dimerization-defective syndecan-2 TMD mutant, 2eT(GL)PC. Moreover, 2eTPC specifically enhanced Tyr 579 and Tyr 857 phosphorylation in the PDGFR cytoplasmic domain, while the TMD mutant failed to support such phosphorylation. Finally, 2eTPC, but not 2eT(GL)PC, induced phosphorylation of Src and PI3 kinase (known downstream effectors of Tyr 579 phosphorylation) and promoted Src-mediated migration of NIH3T3 cells. Taken together, these data suggest that the TMD of a syndecan-2 specifically regulates receptor cytoplasmic domain function and subsequent downstream signaling events controlling cell behavior.
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http://dx.doi.org/10.3390/ijms22157918DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8347082PMC
July 2021

Synthesis and performance evaluation of plastic waste aerogel as sustainable and reusable oil absorbent.

Environ Pollut 2021 Nov 7;288:117717. Epub 2021 Jul 7.

Department of Energy Science and Technology, Environmental Waste Recycle Institute, Myongji University, Yongin, Gyeonggi-do, 17058, Republic of Korea. Electronic address:

Direct utilization of waste polyethylene terephthalate (PET) from the environment to form highly porous aerogel technology for oil absorption is an attractive approach from the view point of green chemistry. However, the oil absorption reaction is limited by low oil absorption capacity and less stability. For now, silica aerogel are used to solve these problem. Our goal is to substitute to these silica aerogel with PET aerogel technology. Herein, we have prepared an environmental waste PET based aerogel with 1.0:0.5 wt% PET, polyvinyl alcohol (PVA), and glutaraldehyde (GA) 0.2% v/v were dispersed in 10 mL DI water, followed by homogenization (30 min), sonication (10 min), and ageing (2 h) at 70 °C. To escape macroscopic cracking, cooling (8 h) at 4 °C was followed by freezing (6 h), freeze drying at -80 °C, and 5 mTorr for 18 h. The hybrid PET aerogel displays excellent performance towards oil absorption. Notably it showed high absorption capacity towards the different oils about 21-40 times its own weight, depending on the viscosity and density of the oil and solvents within 15-35 s, 25 °C, and 2 × 2 cm aerogel size. In addition, the aerogel shows there is no change in structure after several recycles due to high mechanical strength. Furthermore, because of the PET aerogel's high porosity (99.74%) and low density (0.0311 g/cm), close bonding between PET-PVA occurs. Therefore, aerogel shows hydrophobic nature, good mechanical strength, high thermal stability, arrangement of the interconnected fibrillar pore network offers a high surface to volume ratio, low surface energy, high surface roughness, and more reusability. All these parameters are responsible for high oil absorption.
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http://dx.doi.org/10.1016/j.envpol.2021.117717DOI Listing
November 2021

Emerging Role of Syndecans in Extracellular Matrix Remodeling in Cancer.

J Histochem Cytochem 2020 12 6;68(12):863-870. Epub 2020 Jul 6.

Department of Life Sciences, Ewha Womans University, Seoul, Republic of Korea.

The extracellular matrix (ECM) offers a structural basis for regulating cell functions while also acting as a collection point for bioactive molecules and connective tissue cells. To perform pathological functions under a pathological condition, the involved cells need to regulate the ECM to support their altered functions. This is particularly common in the development of cancer. The ECM has been recognized as a key driver of cancer development and progression, and ECM remodeling occurs at all stages of cancer progression. Thus, cancer cells need to change the ECM to support relevant cell surface adhesion receptor-mediated cell functions. In this context, it is interesting to examine how cancer cells regulate ECM remodeling, which is critical to tumor malignancy and metastatic progression. Here, we review how the cell surface adhesion receptor, syndecan, regulates ECM remodeling as cancer progresses, and explore how this can help us better understand ECM remodeling under these pathological conditions.
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http://dx.doi.org/10.1369/0022155420930112DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7711240PMC
December 2020

Drivers' Visual Perception Quantification Using 3D Mobile Sensor Data for Road Safety.

Sensors (Basel) 2020 May 12;20(10). Epub 2020 May 12.

KAIST Urban Design Lab, Department of Civil and Environmental Engineering, KAIST, Daejeon 34141, Korea.

To prevent driver accidents in cities, local governments have established policies to limit city speeds and create child protection zones near schools. However, if the same policy is applied throughout a city, it can be difficult to obtain smooth traffic flows. A driver generally obtains visual information while driving, and this information is directly related to traffic safety. In this study, we propose a novel geometric visual model to measure drivers' visual perception and analyze the corresponding information using the line-of-sight method. Three-dimensional point cloud data are used to analyze on-site three-dimensional elements in a city, such as roadside trees and overpasses, which are normally neglected in urban spatial analyses. To investigate drivers' visual perceptions of roads, we have developed an analytic model of three types of visual perception. By using this proposed method, this study creates a risk-level map according to the driver's visual perception degree in Pangyo, South Korea. With the point cloud data from Pangyo, it is possible to analyze actual urban forms such as roadside trees, building shapes, and overpasses that are normally excluded from spatial analyses that use a reconstructed virtual space.
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http://dx.doi.org/10.3390/s20102763DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7294429PMC
May 2020

High-throughput single-molecule imaging system using nanofabricated trenches and fluorescent DNA-binding proteins.

Biotechnol Bioeng 2020 06 6;117(6):1640-1648. Epub 2020 Apr 6.

School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea.

DNA curtain is a high-throughput system, integrating a lipid bilayer, fluorescence imaging, and microfluidics to probe protein-DNA interactions in real-time and has provided in-depth understanding of DNA metabolism. Especially, the microfluidic platform of a DNA curtain is highly suitable for a biochip. In the DNA curtain, DNA molecules are aligned along chromium nanobarriers, which are fabricated on a slide surface, and visualized using an intercalating dye, YOYO-1. Although the chromium barriers confer precise geometric alignment of DNA, reuse of the slides is limited by wear of the barriers during cleaning. YOYO-1 is rapidly photobleached and causes photocleavage of DNA under continuous laser illumination, restricting DNA observation to a brief time window. To address these challenges, we developed a new nanopatterned slide, upon which carved nanotrenches serve as diffusion barriers. The nanotrenches were robust under harsh cleaning conditions, facilitating the maintenance of surface cleanliness that is essential to slide reuse. We also stained DNA with a fluorescent protein with a DNA-binding motif, fluorescent protein-DNA binding peptide (FP-DBP). FP-DBP was slowly photobleached and did not cause DNA photocleavage. This new DNA curtain system enables a more stable and repeatable investigation of real-time protein-DNA interactions and will serve as a good platform for lab-on-a-chip.
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http://dx.doi.org/10.1002/bit.27331DOI Listing
June 2020

Liver X Receptor α-Induced Cannabinoid Receptor 2 Inhibits Ubiquitin-Specific Peptidase 4 Through miR-27b, Protecting Hepatocytes From TGF-β.

Hepatol Commun 2019 Oct 5;3(10):1373-1387. Epub 2019 Aug 5.

College of Pharmacy and Research Institute of Pharmaceutical Sciences Seoul National University Seoul Korea.

Liver X receptor-alpha (LXRα) acts as a double-edged sword in different biological situations. Given the elusive role of LXRα in hepatocyte viability, this study investigated whether LXRα protects hepatocytes from injurious stimuli and the underlying basis. LXRα activation prevented hepatocyte apoptosis from CCl challenges in mice. Consistently, LXRα protected hepatocytes specifically from transforming growth factor-beta (TGF-β), whereas LXRα deficiency aggravated TGF-β-induced hepatocyte injury. In the Gene Expression Omnibus database analysis for LXR mice, TGF-β receptors were placed in the core network. Hierarchical clustering and correlation analyses enabled us to find cannabinoid receptor 2 (CB2) as a gene relevant to LXRα. In human fibrotic liver samples, both LXRα and CB2 were lower in patients with septal fibrosis and cirrhosis than those with portal fibrosis. LXRα transcriptionally induced CB2; CB2 then defended hepatocytes from TGF-β. In a macrophage depletion model, JWH133 (a CB2 agonist) treatment prevented toxicant-induced liver injury. MicroRNA 27b (miR-27b) was identified as an inhibitor of ubiquitin-specific peptidase 4 (USP4), deubiquitylating TGF-β receptor 1 (TβRI), downstream from CB2. Liver-specific overexpression of LXRα protected hepatocytes from injurious stimuli and attenuated hepatic inflammation and fibrosis. : LXRα exerts a cytoprotective effect against TGF-β by transcriptionally regulating the CB2 gene in hepatocytes, and CB2 then inhibits USP4-stabilizing TβRI through miR-27b. Our data provide targets for the treatment of acute liver injury.
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http://dx.doi.org/10.1002/hep4.1415DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6771303PMC
October 2019

Self-Formulated Na-Based Dual-Ion Battery Using Nonflammable SO -Based Inorganic Liquid Electrolyte.

Small 2021 Mar 22;17(9):e1902144. Epub 2019 Aug 22.

Department of Energy Engineering, Hanyang University, Seoul, 04763, Republic of Korea.

Sodium secondary batteries have gained much attention as alternative power sources to replace lithium secondary batteries. However, some technical issues must be solved to ensure their success. Here, a highly safe and cost-effective Na-based dual-ion battery system employing self-formulated CuCl cathode material starting from a mixture of Cu and NaCl in conjunction with a nonflammable NaAlCl ·2SO inorganic liquid electrolyte is demonstrated. It is found that CuCl is spontaneously formed by redox coupling of Cu/Cu(I) and SO /SO anion radical. In the proposed battery, Na and Cl are employed as energy carriers for the anode and cathode, respectively, and it is further demonstrated that the Na-metal-free battery configuration is possible using a hard carbon anode. Owing to the use of cheap electrode materials and a highly conductive and safe electrolyte, the proposed batteries deserve to be regarded as a promising approach for next-generation Na rechargeable batteries.
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http://dx.doi.org/10.1002/smll.201902144DOI Listing
March 2021

Lithium-Ion Intercalation into Graphite in SO-Based Inorganic Electrolyte toward High-Rate-Capable and Safe Lithium-Ion Batteries.

ACS Appl Mater Interfaces 2019 Mar 20;11(9):9054-9061. Epub 2019 Feb 20.

Department of Energy Engineering , Hanyang University , Seoul 133-791 , Republic of Korea.

Herein, we have identified that lithium ions in an SO-based inorganic electrolyte reversibly intercalate and deintercalate into/out of graphite electrode using ex situ X-ray diffraction and various electrochemical methods. X-ray photoelectron spectroscopy shows that the solid electrolyte interphase on the graphite electrode is mainly composed of inorganic compounds, such as LiCl and lithium sulfur-oxy compounds. Graphite electrode in SO-based inorganic electrolyte has stable capacity retention up to 100 cycles and outstanding rate capability performance. This can be attributed to low interfacial impedance and high ionic conductivity of SO-based inorganic electrolyte, which are superior to those of conventional organic electrolytes. Considering the remarkable rate capability and intrinsically nonflammable properties of the electrolyte, use of graphite and an SO electrolyte will likely facilitate the development of advanced lithium-ion batteries.
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http://dx.doi.org/10.1021/acsami.8b20025DOI Listing
March 2019

Dendrite-Free Li Metal Anode for Rechargeable Li-SO Batteries Employing Surface Modification with a NaAlCl-2SO Electrolyte.

ACS Appl Mater Interfaces 2018 Oct 25;10(40):34699-34705. Epub 2018 Sep 25.

Department of Energy Engineering , Hanyang University , 222 Wangsimni-ro , Seongdong-gu, Seoul 04763 , Republic of Korea.

Dendritic growth of a Li metal anode during cycling is one of major issues to be addressed for practical application of Li metal rechargeable batteries. Herein, we demonstrate that surface modification of Li metal with a Na-containing SO electrolyte can be an effective way to prevent dendritic Li growth during cell operation. The surface-modified Li metal anode exhibited no dendritic deposits even under a high areal capacity (5 mA h cm) and a high current density (3 mA cm), whereas the unmodified anode showed typical filamentary Li deposition. The surface-modified Li metal anode also demonstrated significantly enhanced electrochemical performance, which could be attributed to the newly formed Na-containing inorganic surface layer that exhibits uniform and dense properties. Consequently, surface modification with a Na-containing SO inorganic electrolyte is suggested as one of the most effective ways to realize a highly stable Li metal anode with dendrite-free Li deposition for Li metal-based rechargeable batteries.
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http://dx.doi.org/10.1021/acsami.8b08731DOI Listing
October 2018

FXR Inhibits Endoplasmic Reticulum Stress-Induced NLRP3 Inflammasome in Hepatocytes and Ameliorates Liver Injury.

Cell Rep 2018 09;24(11):2985-2999

College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul 08826, Korea. Electronic address:

Endoplasmic reticulum (ER) stress is associated with liver injury and fibrosis, and yet the hepatic factors that regulate ER stress-mediated inflammasome activation remain unknown. Here, we report that farnesoid X receptor (FXR) activation inhibits ER stress-induced NACHT, LRR, and PYD domains-containing protein 3 (NLRP3) inflammasome in hepatocytes. In patients with hepatitis B virus (HBV)-associated hepatic failure or non-alcoholic fatty liver disease, and in mice with liver injury, FXR levels in the liver inversely correlated with the extent of NLRP3 inflammasome activation. Fxr deficiency in mice augmented the ability of ER stress to induce NLRP3 and thioredoxin-interacting protein (TXNIP), whereas FXR ligand activation prevented it, ameliorating liver injury. FXR attenuates CCAAT-enhancer-binding protein homologous protein (CHOP)-dependent NLRP3 overexpression by inhibiting ER stress-mediated protein kinase RNA-like endoplasmic reticulum kinase (PERK) activation. Our findings implicate miR-186 and its target, non-catalytic region of tyrosine kinase adaptor protein 1 (NCK1), in mediating the inhibition of ER stress by FXR. This study provides the insights on how FXR regulation of ER stress ameliorates hepatocyte death and liver injury and on the molecular basis of NLRP3 inflammasome activation.
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http://dx.doi.org/10.1016/j.celrep.2018.07.068DOI Listing
September 2018

Multiscale Engineered Si/SiO Nanocomposite Electrodes for Lithium-Ion Batteries Using Layer-by-Layer Spray Deposition.

ACS Appl Mater Interfaces 2018 May 26;10(18):15624-15633. Epub 2018 Apr 26.

Department of Materials , University of Oxford , Parks Road , Oxford OX1 3PH , United Kingdom.

Si-based high-capacity materials have gained much attention as an alternative to graphite in Li-ion battery anodes. Although Si additions to graphite anodes are now commercialized, the fraction of Si that can be usefully exploited is restricted due to its poor cyclability arising from the large volume changes during charge/discharge. Si/SiO nanocomposites have also shown promising behavior, such as better capacity retention than Si alone because the amorphous SiO helps to accommodate the volume changes of the Si. Here, we demonstrate a new electrode architecture for further advancing the performance of Si/SiO nanocomposite anodes using a scalable layer-by-layer atomization spray deposition technique. We show that particulate C interlayers between the current collector and the Si/SiO layer and between the separator and the Si/SiO layer improved electrical contact and reduced irreversible pulverization of the Si/SiO significantly. Overall, the multiscale approach based on microstructuring at the electrode level combined with nanoengineering at the material level improved the capacity, rate capability, and cycling stability compared to that of an anode comprising a random mixture of the same materials.
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http://dx.doi.org/10.1021/acsami.8b00370DOI Listing
May 2018

Accurate Mobile Urban Mapping via Digital Map-Based SLAM.

Sensors (Basel) 2016 08 18;16(8). Epub 2016 Aug 18.

Department of Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea.

This paper presents accurate urban map generation using digital map-based Simultaneous Localization and Mapping (SLAM). Throughout this work, our main objective is generating a 3D and lane map aiming for sub-meter accuracy. In conventional mapping approaches, achieving extremely high accuracy was performed by either (i) exploiting costly airborne sensors or (ii) surveying with a static mapping system in a stationary platform. Mobile scanning systems recently have gathered popularity but are mostly limited by the availability of the Global Positioning System (GPS). We focus on the fact that the availability of GPS and urban structures are both sporadic but complementary. By modeling both GPS and digital map data as measurements and integrating them with other sensor measurements, we leverage SLAM for an accurate mobile mapping system. Our proposed algorithm generates an efficient graph SLAM and achieves a framework running in real-time and targeting sub-meter accuracy with a mobile platform. Integrated with the SLAM framework, we implement a motion-adaptive model for the Inverse Perspective Mapping (IPM). Using motion estimation derived from SLAM, the experimental results show that the proposed approaches provide stable bird's-eye view images, even with significant motion during the drive. Our real-time map generation framework is validated via a long-distance urban test and evaluated at randomly sampled points using Real-Time Kinematic (RTK)-GPS.
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http://dx.doi.org/10.3390/s16081315DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5017480PMC
August 2016

Properties and in vitro drug release of hyaluronic acid-hydroxyethyl cellulose hydrogels for transdermal delivery of isoliquiritigenin.

Carbohydr Polym 2016 08 8;147:473-481. Epub 2016 Apr 8.

Department of Fine Chemistry, Seoul National University of Science and Technology, 232 Gongneung-ro, Nowon-gu, Seoul 01811, South Korea. Electronic address:

In the present study, the properties of hydrogel systems based on hyaluronic acid (HA)-hydroxyethyl cellulose (HEC) were investigated for effective transdermal delivery of isoliquiritigenin (ILTG). Hydrogels were synthesized by chemical cross-linking, and network structures were characterised using scanning electron microscopy (SEM) and surface area analyser. Texture properties and swelling of HA-HEC hydrogels were found to be closely linked to cross-linker concentration and swelling medium. Water in HA-HEC hydrogels was found to exist mostly in the form of free water. The viscoelasticity and the network stabilization of the hydrogels were analysed via rheological studies. The release kinetics of the hydrogel followed Fickian diffusion mechanism. In an in vitro skin penetration study, the system substantially improved the delivery of ILTG into the skin. These results indicate that the hydrogel system composed of HA and HEC has potential as a transdermal delivery system, with cross-linking density and the swelling medium influencing the properties.
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http://dx.doi.org/10.1016/j.carbpol.2016.04.021DOI Listing
August 2016

Medication adherence communications in community pharmacies: A naturalistic investigation.

Patient Educ Couns 2016 Mar 22;99(3):386-392. Epub 2015 Oct 22.

Department of Pharmacy and Health Systems Sciences, Northeastern University, Boston, MA, USA.

Objective: To describe the extent of pharmacy detection and monitoring of medication non-adherence, and solutions offered to improve adherence.

Methods: Participants were 60 residents of the Boston area who had a generic chronic medication with 30 day supplies from their usual pharmacy. Participants received a duplicate prescription which they filled at a different pharmacy. For 5 months, participants alternated between the two pharmacies, creating gaps in their refill records at both pharmacies but no gaps in their medication adherence. Participants followed a scripted protocol and after each pharmacy visit reported their own and the pharmacy staff's behavior.

Results: Across 78 unique community pharmacies and 260 pharmacy visits, pharmacies were inconsistent and inadequate in asking if participants had questions, discussing the importance of adherence, providing adequate consultations with new medication, and detecting and intervening on non-adherence. Insurers rarely contacted the participants about adherence concerns.

Conclusion: There is a need for more structured intervention systems to ensure pharmacists are consistently and adequately educating patients and detecting/managing potential medication non-adherence.

Practice Implications: The present study calls for more attention to building infrastructure in pharmacy practice that helps pharmacists more consistently identify, monitor, and intervene on medication adherence.
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http://dx.doi.org/10.1016/j.pec.2015.10.003DOI Listing
March 2016

Improvement of electrical blood hematocrit measurements under various plasma conditions using a novel hematocrit estimation parameter.

Biosens Bioelectron 2012 May 14;35(1):416-420. Epub 2012 Feb 14.

School of Mechatronics, Gwangju Institute of Science and Technology (GIST), Gwangju 500-712, Republic of Korea; Department of Medical System Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 500-712, Republic of Korea; Department of Nanobio Material and Electronics, Gwangju Institute of Science and Technology (GIST), Gwangju 500-712, Republic of Korea. Electronic address:

This paper presents an electrical method for measurement of Hematocrit (HCT) using a novel HCT estimation parameter. Particularly in the case of electrical HCT measurements, the measurement error generally increases with changes in the electrical conditions of the plasma such as conductivity and osmolality. This is because the electrical properties of blood are a function not only of HCT, but also of the electrical conditions in the plasma. In an attempt to reduce the measurement errors, we herein propose a novel HCT estimation parameter reflecting the characteristics of both the changes in volume of red blood cells (RBCs) and electrical conditions of plasma, simultaneously. In order to characterize the proposed methods under various electrical conditions of plasma, we prepared twelve blood samples such as four kinds of plasma conditions (hypotonic, isotonic, two kinds of hypertonic conditions) at three different HCT levels. Using linear regression analysis, we confirmed that the proposed parameter was highly correlated with reference HCT (HCT(ref.)) values measured by microcentrifugation. Thus, the HCT measurement error was less than 4%, despite considerable variations in the conductivity and osmolality of the plasma at conditions of the HCT(ref.) of 20%. Multiple linear regression analysis showed that the proposed HCT estimation parameter also yielded a lower measurement error (1%) than the other parameter previously used for the same purpose. Thus, these preliminary results suggest that proposed method could be used for accurate, fast, easy, and reproducible HCT measurements in medical procedures.
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http://dx.doi.org/10.1016/j.bios.2012.02.010DOI Listing
May 2012

Characterization of the molecular features and expression patterns of two serine proteases in Hermetia illucens (Diptera: Stratiomyidae) larvae.

BMB Rep 2011 Jun;44(6):387-92

National Academy of Agricultural Science, Rural Development Administration, Suwon, Korea.

To investigate the molecular scavenging capabilities of the larvae of Hermetia illucens, two serine proteases (SPs) were cloned and characterized. Multiple sequence alignments and phylogenetic tree analysis of the deduced amino acid sequences of Hi-SP1 and Hi-SP2 were suggested that Hi-SP1 may be a chymotrypsin- and Hi-SP2 may be a trypsin-like protease. Hi-SP1 and Hi-SP2 3-D homology models revealed that a catalytic triad, three disulfide bonds, and a substrate-binding pocket were highly conserved, as would be expected of a SP. E. coli expressed Hi-SP1 and Hi-SP2 showed chymotrypsin or trypsin activities, respectively. Hi-SP2 mRNAs were consistently expressed during larval development. In contrast, the expression of Hi-SP1 mRNA fluctuated between feeding and molting stages and disappeared at the pupal stages. These expression pattern differences suggest that Hi-SP1 may be a larval specific chymotrypsin-like protease involved with food digestion, while Hi-SP2 may be a trypsin-like protease with diverse functions at different stages.
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http://dx.doi.org/10.5483/BMBRep.2011.44.6.387DOI Listing
June 2011

Pharmacogenetic regulation of acetylcholinesterase activity in Drosophila reveals the regulatory mechanisms of AChE inhibitors in synaptic plasticity.

Neurochem Res 2011 May 9;36(5):879-93. Epub 2011 Feb 9.

National Academy of Agricultural Science, Rural Development Administration, Suwon 441-707, Republic of Korea.

We conducted experiments in Drosophila to investigate the consequences of altered acetylcholinesterase (AChE) activity in the nervous system. In ace hypomorphic mutant larvae, the amount of ace mRNA and the activity of AChE both in vivo and in vitro were significantly reduced compared with those of controls. Reduced Ace in Drosophila larvae resulted in significant down-regulation of branch length and the number of boutons in Type 1 glutamatergic neuromuscular junctions (NMJs). These defects in ace hypomorphic mutant larvae were suppressed when Musca domestica AChE was transgenically expressed. Because AChE inhibitors are utilized for medications for Alzheimer's disease, we investigated whether pharmacological inhibition of AChE activity induced any synaptic defects. We found that controls exposed to a sublethal dose of DDVP phenocopied the synaptic structural defects of the ace hypomorphic mutant. These results suggest that down-regulation of AChE activity, regardless of whether it is due to genetic or pharmacological manipulations, results in altered synaptic architecture. Our study suggests that exposure to AChE inhibitors for 6-12 months may induce altered synaptic architectures in human brains with Alzheimer's diseases, similar to those reported here. These changes may underlie or contribute to the loss of efficacy of AChE inhibitors after prolonged treatment.
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http://dx.doi.org/10.1007/s11064-011-0418-1DOI Listing
May 2011

Overactive bladder is not only overactive but also hypersensitive.

Urology 2010 May 21;75(5):1053-9. Epub 2010 Jan 21.

Department of Urology, Yonsei University College of Medicine, Seoul, Korea.

Objectives: To evaluate differences in bladder filling sensations and current perception threshold (CPT) values between patients with and without overactive bladder (OAB), and to further investigate the correlation between CPT values and voiding patterns in OAB patients.

Methods: Detrusor overactivity and bladder volumes at first sensation of bladder filling, first desire to void, and strong desire to void during filling cystometry were compared between 55 female patients with OAB and 42 with non-OAB. CPT measurements from the bladder mucosa taken after neuroselective electrostimulation at frequencies of 2000, 250, and 5 Hz were compared between the 2 groups. In OAB patients, the correlations between CPT values and voiding variables based on 3-day bladder diaries were investigated.

Results: OAB patients showed significantly more detrusor overactivity than non-OAB patients (P <.05). Bladder volumes at first sensation of bladder filling, first desire to void, and strong desire to void were significantly lower in OAB patients than in non-OAB patients (P <.05). CPT values at all 3 frequencies were also significantly lower in OAB patients (P <.05). The total number of urgency episodes correlated with CPT values at 250 (r = -0.274, P = .045) and 5 Hz (r = -0.293, P = .032). The total number of urge incontinence episodes also correlated with CPT values at 250 (r = -0.279, P = .041) and 5 Hz (r = -0.272, P = .046).

Conclusions: Bladder sensory profiles displayed a more sensitive bladder in OAB patients compared with non-OAB subjects. OAB patients may have bladders that are not only overactive, but also hypersensitive.
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http://dx.doi.org/10.1016/j.urology.2009.10.045DOI Listing
May 2010
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