Altered functional connectivity in default mode network in Internet gaming disorder: Influence of childhood ADHD

Lee, Deokjong,Lee, Junghan,Lee, Jung Eun,Jung, Young-Chul Elsevier 2017 Progress in neuro-psychopharmacology & biological Vol.75 No.-

<P><B>Abstract</B></P> <P><B>Objective</B></P> <P>Internet gaming disorder (IGD) is a type of behavioral addiction characterized by abnormal executive control, leading to loss of control over excessive gaming. Attention deficit and hyperactivity disorder (ADHD) is one of the most common comorbid disorders in IGD, involving delayed development of the executive control system, which could predispose individuals to gaming addiction. We investigated the influence of childhood ADHD on neural network features of IGD.</P> <P><B>Methods</B></P> <P>Resting-state functional magnetic resonance imaging analysis was performed on 44 young, male IGD subjects with and without childhood ADHD and 19 age-matched, healthy male controls. Posterior cingulate cortex (PCC)-seeded connectivity was evaluated to assess abnormalities in default mode network (DMN) connectivity, which is associated with deficits in executive control.</P> <P><B>Results</B></P> <P>IGD subjects without childhood ADHD showed expanded functional connectivity (FC) between DMN-related regions (PCC, medial prefrontal cortex, thalamus) compared with controls. These subjects also exhibited expanded FC between the PCC and brain regions implicated in salience processing (anterior insula, orbitofrontal cortex) compared with IGD subjects with childhood ADHD. IGD subjects with childhood ADHD showed expanded FC between the PCC and cerebellum (crus II), a region involved in executive control. The strength of connectivity between the PCC and cerebellum (crus II) was positively correlated with self-reporting scales reflecting impulsiveness.</P> <P><B>Conclusion</B></P> <P>Individuals with IGD showed altered PCC-based FC, the characteristics of which might be dependent upon history of childhood ADHD. Our findings suggest that altered neural networks for executive control in ADHD would be a predisposition for developing IGD.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Hypothesis about causal factors of internet gaming disorder is proposed. </LI> <LI> Internet gaming disorder shows altered functional connectivity in default mode network. </LI> <LI> Internet gaming disorder with childhood ADHD shows altered functional connectivity associated with executive control deficit. </LI> </UL> </P>

Impaired anterior insular activation during risky decision making in young adults with internet gaming disorder

Lee, Deokjong,Lee, Junghan,Yoon, Kang Joon,Kee, Namkoong,Jung, Young-Chul Wolters Kluwer Health | Lippincott Williams Wilkin 2016 NEUROREPORT - Vol.27 No.8

<P>Internet gaming disorder is defined as excessive and compulsive use of the internet to engage in games that leads to clinically significant psychosocial impairment. We tested the hypothesis that individuals with internet gaming disorder would be less sensitive to high-risk situations and show aberrant brain activation related to risk prediction processing. Young adults with internet gaming disorder underwent functional MRI while performing a risky decision-making task. The healthy control group showed stronger activations within the dorsal attention network and the anterior insular cortex, which were not found in the internet gaming disorder group. Our findings imply that young adults with internet gaming disorder show impaired anterior insular activation during risky decision making, which might make them vulnerable when they need to adapt new behavioral strategies in high-risk situations. Copyright (C) 2016 Wolters Kluwer Health, Inc. All rights reserved.</P>

Resistive Switching WOx‐Au Core‐Shell Nanowires with Unexpected Nonwetting Stability Even when Submerged Under Water

Lee, Seunghyup,Lee, Junghan,Park, Jinjoo,Choi, Youngwoo,Yong, Kijung WILEY‐VCH Verlag 2012 ADVANCED MATERIALS Vol.24 No.18

<P><B>The resistive switching (RS) characteristics of a tungsten oxide (WO<SUB>x</SUB>)‐Au core‐shell nanowire device array</B> is demonstrated for the first time. In addition to the stable bipolar RS characteristics, the nanowire structure of our RS devices provides superhydrophobic properties. The superhydrophobic RS nanowires repelled water that was poured over, such that the device was protected from failure by water contact‐driven leakage currents. Moreover, surprisingly, the devices still work even with when the device is submerged underwater.</P>

PEG-ylated cationic CdSe/ZnS QDs as an efficient intracellular labeling agent

Lee, Junghan,Kim, Junwon,Park, Eunjung,Jo, Shineun,Song, Rita Royal Society of Chemistry 2008 Physical chemistry chemical physics Vol.10 No.13

<P>Quantum dots (QDs) have size-tunable optical properties, such as photostability, strong photoluminescence and a large Stokes-shift, which make it possible to adapt them to various biological applications. In many cases, surface modification of QDs by carboxylate ligands has been extensively studied. However, there have been few applications on QDs modified with a potential cationic ligand such as amine. In this study, we synthesized robust amine-functionalized QDs and modified their surface with poly(ethylene glycol) for long-term stability. These QDs showed an excellent stability over a broad pH-range and remarkable internalization efficiency into living cells.</P> <P>Graphic Abstract</P><P>Robust amine-functionalized QDs were prepared and their surface modified with polyethylene glycol for long-term stability. These QDs showed an excellent stability over a broad pH range and remarkable internalization efficiency into the living cells. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=b801317a'> </P>

Regional Gray Matter Volume Related to High Occupational Stress in Firefighters

Lee Deokjong,Kim Woojin,Lee Jung Eun,Lee Junghan,Lee Seung-Koo,Chang Sei-Jin,Jeung Da Yee,Hyun Dae-Sung,Ryu Hye-Yoon,Kim Changsoo,Jung Young-Chul 대한의학회 2021 Journal of Korean medical science Vol.36 No.50

Background: Firefighters inevitably encounter emotionally and physically stressful situations at work. Even firefighters without diagnosed post-traumatic stress disorder receive clinical attention because the nature of the profession exposes them to repetitive trauma and high occupational stress. This study investigated gray matter abnormalities related to high occupational stress in firefighters using voxel-based morphometry (VBM) and surface-based morphometry (SBM). Methods: We assessed 115 subjects (112 males and 3 females) using magnetic resonance imaging and evaluated occupational stress by the Korean Occupational Stress Scale-26 (KOSS-26). Subjects were classified into highly or lowly stressed groups based on the median value of the KOSS-26. Results: In VBM analysis, we found that firefighters with high occupational stress had lower gray matter volume (GMV) in both sides of the insula, the left amygdala, the right medial prefrontal cortex (mPFC), and the anterior cingulate cortex than firefighters with low occupational stress. In SBM analysis based on regions of interest, the GMV of the bilateral insula and right mPFC were also lower in the highly stressed group. Within the highly stressed group, low GMV of the insula was significantly correlated with the length of service (left: r = −0.347, P = 0.009; right: r = −0.333, P = 0.012). Conclusion: Our findings suggest that regional GMV abnormalities are related to occupational stress. Regional gray matter abnormalities and related emotional dysregulation may contribute to firefighter susceptibility to burnout.

Quantum Dot‐Based Screening System for Discovery of G Protein‐Coupled Receptor Agonists

Lee, Junghan,Kwon, Yong‐,Jun,Choi, Youngseon,Kim, Hi Chul,Kim, Keumhyun,Kim, JinYeop,Park, Sun,Song, Rita WILEY‐VCH Verlag 2012 Chembiochem Vol.13 No.10

<P><B>Abstract</B></P><P>Cellular imaging has emerged as an important tool to unravel biological complexity and to accelerate the drug‐discovery process, including cell‐based screening, target identification, and mechanism of action studies. Recently, semiconductor nanoparticles known as quantum dots (QDs) have attracted great interest in cellular imaging applications due to their unique photophysical properties such as size, tunable optical property, multiplexing capability, and photostability. Herein, we show that QDs can also be applied to assay development and eventually to high‐throughput/content screening (HTS/HCS) for drug discovery. We have synthesized QDs modified with PEG and primary antibodies to be used as fluorescent probes for a cell‐based HTS system. The G protein‐coupled receptor (GPCR) family is known to be involved in most major diseases. We therefore constructed human osteosarcoma (U2OS) cells that specifically overexpress two types of differently tagged GPCRs: influenza hemagglutinin (HA) peptide‐tagged κ‐opioid receptors (κ‐ORs) and GFP‐tagged A3 adenosine receptors (A3AR). In this study, we have demonstrated that 1) anti‐HA antibody‐conjugated QDs could specifically label HA‐tagged κ‐ORs, 2) subsequent treatment of QD‐tagged GPCR agonists allowed agonist‐induced translocation to be monitored in real time, 3) excellent emission spectral properties of QD permitted the simultaneous detection of two GPCRs in one cell, and 4) the robust imaging capabilities of the QD–antibody conjugates could lead to reproducible quantitative data from high‐content cellular images. These results suggest that the present QD‐based GPCR inhibitor screening system can be a promising platform for further drug screening applications.</P>

Compromised Prefrontal Cognitive Control Over Emotional Interference in Adolescents with Internet Gaming Disorder

Lee, Junghan,Lee, Seojung,Chun, Ji Won,Cho, Hyun,Kim, Dai-jin,Jung, Young-Chul Mary Ann Liebert 2015 CYBERPSYCHOLOGY BEHAVIOR AND SOCIAL NETWORKING Vol.18 No.11

Selective targeting of cellular nucleus using positively-charged quantum dots.

Lee, Junghan,Choi, Youngseon,Cho, Yoojin,Song, Rita American Scientific Publishers 2013 Journal of Nanoscience and Nanotechnology Vol.13 No.1

<P>Developing highly selective probes for subcellular regions such as nucleus and cytoplamic organelles is of great interest for cellular imaging and high content screening analysis for biology and medicine. Cytoplasmic delivery of QDs has been well-understood, while nuclear delivery of QDs has been a challenge due to the unique structural characteristics of cell nucleus. In this study, we systematically investigated nucleus penetrating properties of small-sized ligand-exchanged QDs with either positive or negative surface charges in the similar size range of hydrodynamic diameter (7-10 nm). We found that the positively-charged QDs efficiently stain the nucleus in fixed HeLa cells as well as label nucleolar compartments in live HeLa cells. In contrast, the negatively charged QDs with the similar size range stain only the cytoplam in either fixed or live cells. The charge-dependent labeling pattern allowed us to simultaneously perform multiplex imaging of nuclues and cytoplasm. This study offers an insight into efficient nuclear delivery of nanoparticles such as QDs of which surface charge and size are critical for intracelllar localization and delivery.</P>

Modeling of frost layer growth considering frost porosity

Lee, Jaehwan,Kim, Junghan,Kim, Dong Rip,Lee, Kwan-Soo Elsevier 2018 INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER - Vol.126 No.1

<P><B>Abstract</B></P> <P>A numerical model for predicting frost layer growth based on computational fluid dynamics is developed. This model can predict the growth behavior of a highly porous frost layer formed by desublimation. A new volumetric mass transfer rate equation is proposed, which can consider water vapor penetration into a frost layer. The model is validated through experimental results under various operating conditions and used for analyzing the frost layer growth process. The density distribution inside the frost layer is almost linearly changed in the direction perpendicular to the cooling surface under the operating conditions favorable for desublimation, showing different characteristics from the case in the operating conditions favorable for freezing after condensation. In addition, the average mass transfer rate is analyzed as a function of time. As time passes, the porosity of the frost layer decreases and the mass transfer rate due to water vapor penetration decreases gradually.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Frosting model considering frost porosity was proposed. </LI> <LI> A mass transfer rate considering water vapor penetration into frost layer was defined. </LI> <LI> The proposed model was validated using various experimental results. </LI> <LI> Frost layer growth behavior under conditions for desublimation was investigated. </LI> </UL> </P>

Surface chemistry controlled superhydrophobic stability of W₁₈O₄₉ nanowire arrays submerged underwater

Lee, Junghan,Yong, Kijung The Royal Society of Chemistry 2012 Journal of materials chemistry Vol.22 No.38

<P>Superhydrophobic surfaces with quasi-aligned W<SUB>18</SUB>O<SUB>49</SUB> nanowire (NW) arrays were fabricated using a simple thermal evaporation and surface chemistry modification method. The fabricated superhydrophobic W<SUB>18</SUB>O<SUB>49</SUB> NW surface has shown reliable stability in submerged underwater conditions, exhibiting silvery surfaces caused by total reflection between the water layer and air pockets. The stability of superhydrophobicity in underwater conditions decreased exponentially as the hydrostatic pressure applied to the substrates increased. In addition, variations in stability were investigated according to changes in the surface energy of W<SUB>18</SUB>O<SUB>49</SUB> NW arrays. As surface energy decreased, the underwater stability of the superhydrophobic surface increased sharply. Based on these results, the models explaining tendencies of superhydrophobic stability underwater resulting from hydrostatic pressure and surface energy were designed. This study on fabrication and modeling of underwater superhydrophobic stability will help in designing highly stable superhydrophobic surfaces and broadening fields of superhydrophobic applications.</P> <P>Graphic Abstract</P><P>Superhydrophobic surfaces with quasi-aligned W<SUB>18</SUB>O<SUB>49</SUB> nanowire (NW) arrays were fabricated using a simple thermal evaporation and surface chemistry modification method. Underwater stability of W<SUB>18</SUB>O<SUB>49</SUB> NW arrays was analyzed and the models explaining tendencies of superhydrophobic stability underwater were designed. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2jm34307j'> </P>