Publications by authors named "Sanghyeon Kim"

47 Publications

Insecticide resistance trait may contribute to genetic cluster change in Bemisia tabaci MED (Hemiptera: Aleyrodidae) as a potential driving force.

Pest Manag Sci 2021 Apr 12. Epub 2021 Apr 12.

Entomology Program, Department of Agricultural Biotechnology, Seoul National University, 1, Gwanak-ro, Gwanak-gu, Seoul, 08826, Republic of Korea.

Background: Previously, we had reported that the majority of the Bemisia tabaci Mediterranean (MED) populations converged from two dominant genetic clusters (cluster 1 and 2) to one (cluster 2) during one year in greenhouse tomatoes in Korea. To find possible mechanisms for this phenomenon, we investigated the concurrent changes in resistance traits of the two clusters for three insecticide classes (organophosphate, pyrethroid, and neonicotinoid).

Results: Since the resistance mutation frequencies in regional samples were either high (i.e., the voltage-sensitive sodium channel L925I/T929V mutations and the F392 acetylcholinesterase 1 mutation) or zero (the nicotinic acetylcholine receptor R81T mutation), no meaningful correlation between the resistance allele frequency and genetic cluster was deduced. However, the actual resistance levels to all three insecticide classes were significantly higher in cluster 2 than those in cluster 1, suggesting that cluster 2 has a higher resistance potential. Furthermore, thiamethoxam treatment to the mixed population of clusters 1 and 2 over three generations exhibited a strong tendency of population change from cluster 1 to cluster 2.

Conclusion: Our results demonstrated that the insecticide resistance trait is one of the driving forces for rapid genetic cluster change in the B. tabaci MED populations.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/ps.6412DOI Listing
April 2021

Arrayed MoS -In Ga As van der Waals Heterostructure for High-Speed and Broadband Detection from Visible to Shortwave-Infrared Light.

Small 2021 Mar 17:e2007357. Epub 2021 Mar 17.

School of Electrical Engineering, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Daejeon, 34141, Republic of Korea.

A high-speed and broadband 5 × 5 photodetector array based on MoS /In Ga As heterojunction is successfully demonstrated to take full advantage of the type-II band-aligned multilayer MoS /In Ga As. The fabricated devices exhibit good uniformity in the Raman spectrum and clear rectifying characteristics. The fabricated MoS /In Ga As photodetectors show good optical performances at a broad wavelength range showing high responsivities corresponding to the detectivity of ≈10 Jones at -3 V for the incident broadband light from 400 to 1550 nm. A very fast photoresponse is also obtained with a small rise/fall time in the order of microseconds both for visible (638 nm) and shortwave infrared (1310 nm). Finally, the image scanning properties of MoS /In Ga As devices are demonstrated for visible and infrared light, indicating that the suggested device is one of the promising options for future broadband imager, which can be integrated on the focal plane arrays (FPAs).
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/smll.202007357DOI Listing
March 2021

Bioinspired Photoresponsive Single Transistor Neuron for a Neuromorphic Visual System.

Nano Lett 2020 12 25;20(12):8781-8788. Epub 2020 Nov 25.

School of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea.

Realizing a neuromorphic-based artificial visual system with low-cost hardware requires a neuromorphic device that can react to light stimuli. This study introduces a photoresponsive neuron device composed of a single transistor, developed by engineering an artificial neuron that responds to light, just like retinal neurons. Neuron firing is activated primarily by electrical stimuli such as current via a well-known single transistor latch phenomenon. Its firing characteristics, represented by spiking frequency and amplitude, are additionally modulated by optical stimuli such as photons. When light is illuminated onto the neuron transistor, electron-hole pairs are generated, and they allow the neuron transistor to fire at lower firing threshold voltage. Different photoresponsive properties can be modulated by the intensity and wavelength of the light, analogous to the behavior of retinal neurons. The artificial visual system can be miniaturized because a photoresponsive neuronal function is realized without bulky components such as image sensors and extra circuits.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.nanolett.0c03652DOI Listing
December 2020

3D Stackable Synaptic Transistor for 3D Integrated Artificial Neural Networks.

ACS Appl Mater Interfaces 2020 Feb 3;12(6):7372-7380. Epub 2020 Feb 3.

School of Electrical Engineering , Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141 , Republic of Korea.

Although they have attracted enormous attention in recent years, software-based and two-dimensional hardware-based artificial neural networks (ANNs) may consume a great deal of power. Because there will be numerous data transmissions through a long interconnection for learning, power consumption in the interconnect will be an inevitable problem for low-power computing. Therefore, we suggest and report 3D stackable synaptic transistors for 3D ANNs, which would be the strongest candidate in future computing systems by minimizing power consumption in the interconnection. To overcome the problems of enormous power consumption, it might be necessary to introduce a 3D stackable ANN platform. With this structure, short vertical interconnection can be realized between the top and bottom devices, and the integration density can be significantly increased for integrating numerous neuromorphic devices. In this paper, we suggest and show the feasibility of monolithic 3D integration of synaptic devices using the channel layer transfer method through a wafer bonding technique. Using a low-temperature processible III-V and composite oxide (AlO/HfO/AlO)-based weight storage layer, we successfully demonstrated synaptic transistors showing good linearity (α/α = 1.8/0.5), a high transconductance ratio (6300), and very good stability. High learning accuracy of 97% was obtained in the training of 1 million MNIST images based on the device characteristics.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acsami.9b22008DOI Listing
February 2020

Monolithic integration of visible GaAs and near-infrared InGaAs for multicolor photodetectors by using high-throughput epitaxial lift-off toward high-resolution imaging systems.

Sci Rep 2019 Dec 9;9(1):18661. Epub 2019 Dec 9.

Department of Materials Science and Engineering, Seoul National University, Gwanak-ro 1, Gwanak-gu, Seoul, 08826, Republic of Korea.

In this study, multicolor photodetectors (PDs) fabricated by using bulk p-i-n-based visible GaAs and near-infrared InGaAs structures were monolithically integrated through a high-throughput epitaxial lift-off (ELO) process. To perform multicolor detection in integrated structures, GaAs PDs were transferred onto InGaAs PDs by using a YO bonding layer to simultaneously detect visible and near-infrared photons and minimize the optical loss. As a result, it was found that the GaAs top PD and InGaAs bottom PD were vertically aligned without tilting in x-ray diffraction (XRD) measurement. A negligible change in the dark currents for each PD was observed in comparison with reference PDs through electrical characterization. Furthermore, through optical measurements and simulation, photoresponses were clearly revealed in the visible and near-infrared band for the material's absorption region, respectively. Finally, we demonstrated the simultaneous multicolor detection of the visible and near-infrared region,which implies individual access to each PD without mutual interference. These results are a significant improvement for the fabrication of multicolor PDs that enables the formation of bulk-based multicolor PDs on a single substrate with a high pixel density and nearly perfect vertical alignment for high-resolution multicolor imaging.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41598-019-55159-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6901491PMC
December 2019

Strategy toward the fabrication of ultrahigh-resolution micro-LED displays by bonding-interface-engineered vertical stacking and surface passivation.

Nanoscale 2019 Dec;11(48):23139-23148

Information and Electronics Research Institute, Korea Advanced Institute of Science and Technology (KAIST), Daehak-ro 291, Yuseong-gu, Daejeon 34141, Republic of Korea.

In this study, we proposed a strategy to fabricate vertically stacked subpixel (VSS) micro-light-emitting diodes (μ-LEDs) for future ultrahigh-resolution microdisplays. At first, to vertically stack the LED with different colors, we successfully adopted a bonding-interface-engineered monolithic integration method using SiO2/SiNx distributed Bragg reflectors (DBRs). It was found that an intermediate DBR structure could be used as the bonding layer and color filter, which could reflect and transmit desired wavelengths through the bonding interface. Furthermore, the optically pumped μ-LED array with a pitch of 0.4 μm corresponding to the ultrahigh-resolution of 63 500 PPI could be successfully fabricated using a typical semiconductor process, including electron-beam lithography. Compared with the pick-and-place strategy (limited by machine alignment accuracy), the proposed strategy leads to the fabrication of significantly improved high-density μ-LEDs. Finally, we systematically investigated the effects of surface traps using time-resolved photoluminescence (TRPL) and two-dimensional simulations. The obtained results clearly demonstrated that performance improvements could be possible by employing optimal passivation techniques by diminishing the pixel size for fabricating low-power and highly efficient microdisplays.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1039/c9nr04423jDOI Listing
December 2019

Differential expression of acetylcholinesterase 1 in response to various stress factors in honey bee workers.

Sci Rep 2019 07 17;9(1):10342. Epub 2019 Jul 17.

Department of Agricultural Biotechnology, College of Agriculture and Life Science, Seoul National University, Seoul, Korea.

The honey bee acetylcholinesterase 1 (AmAChE1) has been suggested to be related to stress response as judged from its elevated expression level under brood rearing-suppressed conditions. To further investigate the involvement of AmAChE1 expression in the stress response and its physiological functions, we analyzed altered expression profiles of AmAChE1 induced by diverse stress factors. In addition, transcription profiles of several heat shock protein (Hsp) genes (hsps) and the vitellogenin (Vg) gene (vg) known as general stress markers were investigated as positive references. Among the tested stress conditions, AmAChE1 expression was induced under the brood rearing-suppressed, crowding and heat shock conditions. The hsps, particularly hsp70 and hsp90, responded to seven of nine stress conditions tested, confirming that hsp expression profiles can serve as a general stress marker. Taken together, AmAChE1 expression is not suitable for using as a stress marker due to its limited response. Nevertheless, AmAChE1 expression appears to be connected, at least in part, to heat shock response and other pathways. Considering that AmAChE1 likely regulates the ACh titer particularly in non-neuronal tissues, thereby modulating the signal cascades mediated by mAChR, the AmAChE1 expression profile under different conditions likely provides important information on its physiological roles in honey bees.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41598-019-46842-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6637154PMC
July 2019

Brain somatic mutations observed in Alzheimer's disease associated with aging and dysregulation of tau phosphorylation.

Nat Commun 2019 07 12;10(1):3090. Epub 2019 Jul 12.

Biomedical Science and Engineering Interdisciplinary Program, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea.

The role of brain somatic mutations in Alzheimer's disease (AD) is not well understood. Here, we perform deep whole-exome sequencing (average read depth 584×) in 111 postmortem hippocampal formation and matched blood samples from 52 patients with AD and 11 individuals not affected by AD. The number of somatic single nucleotide variations (SNVs) in AD brain specimens increases significantly with aging, and the rate of mutation accumulation in the brain is 4.8-fold slower than that in AD blood. The putatively pathogenic brain somatic mutations identified in 26.9% (14 of 52) of AD individuals are enriched in PI3K-AKT, MAPK, and AMPK pathway genes known to contribute to hyperphosphorylation of tau. We show that a pathogenic brain somatic mutation in PIN1 leads to a loss-of-function mutation. In vitro mimicking of haploinsufficiency of PIN1 aberrantly increases tau phosphorylation and aggregation. This study provides new insights into the genetic architecture underlying the pathogenesis of AD.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41467-019-11000-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6626023PMC
July 2019

High Volumetric and Gravimetric Capacity Electrodeposited Mesostructured Sb O Sodium Ion Battery Anodes.

Small 2019 Jun 26;15(23):e1900258. Epub 2019 Apr 26.

Department of Materials Science and Engineering, Materials Research Laboratory, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.

Sodium ion batteries (SIBs) are considered promising alternatives to lithium ion batteries for grid-scale and other energy storage applications because of the broad geographical distribution and low cost of sodium relative to lithium. Here, fabrication and characterization of high gravimetric and volumetric capacity 3D Ni-supported Sb O anodes for SIBs are presented. The electrodes are prepared by colloidal templating and pulsed electrodeposition followed by heat treatment. The colloidal template is optimized to provide large pore interconnects in the 3D scaffold to enable a high active materials loading and accommodate a large volume expansion during cycling. An electrodeposited loading of 1.1 g cm is chosen to enable a combined high gravimetric and volumetric capacity. At this loading, the electrodes exhibit a specific capacity of ≈445 mA h g and a volumetric capacity of ≈488 mA h cm with a capacity retention of 89% after 200 cycles at 200 mA g . The stable cycling performance can be attributed to the 3D metal scaffold, which supports active materials undergoing large volume changes, and an initial heat treatment appears to improve the adhesion of the Sb O to the metal scaffold.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/smll.201900258DOI Listing
June 2019

Transcription of human endogenous retroviruses in human brain by RNA-seq analysis.

PLoS One 2019 3;14(1):e0207353. Epub 2019 Jan 3.

Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden.

Background: Human endogenous retroviruses (HERV) comprise 8% of the human genome and can be classified into at least 31 families. Increased levels of transcripts from the W and H families of HERV have been observed in association with human diseases, such as multiple sclerosis and schizophrenia. Although HERV transcripts have been detected in many tissues and cell-types based on microarray and PCR studies, the extent of HERV expression in different cell-types and diseases state has been less comprehensively studied.

Results: We examined overall transcription of HERV, and particularly of HERV-W and HERV-H elements in human postmortem brain samples obtained from individuals with psychiatric diagnoses (n = 111) and healthy controls (n = 51) by analyzing publicly available RNA sequencing datasets. Sequence reads were aligned to prototypical sequences representing HERV, downloaded from Repbase. We reported a consistent expression (0.1~0.2% of mappable reads) of different HERV families across three regions of human brains. Spearman correlations revealed highly correlated expression levels between three brain regionsacross 475 consensus sequences. By mapping sequences that aligned to the consensus sequences of HERV-W and HERV-H families to individual loci on chromosome 7, more than 60 loci from each family were identified, part of which are being transcribed. The ERVWE1, locus located at chr7q21.2, exhibited high levels of transcription across the three datasets. Notably, we demonstrated a trend of increased expression of overall HERV, as well as HERV-W family in samples from both schizophrenia and bipolar disorder patients.

Conclusions: The current analyses indicate that RNA sequencing is a useful approach for investigating global expression of repetitive elements, such as HERV, in the human genome. HERV-W/H with the tendency of transcription up-regulation in patients suggests potential implication of HERV-W/H in psychiatric diseases.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0207353PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6317784PMC
September 2019

The Stanley Neuropathology Consortium Integrative Database (SNCID) for Psychiatric Disorders.

Neurosci Bull 2019 Apr 27;35(2):277-282. Epub 2018 Nov 27.

Stanley Brain Research Laboratory, Stanley Medical Research Institute, 9800 Medical Center Drive, Rockville, MD, 20850, USA.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s12264-018-0314-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6426894PMC
April 2019

Diffusion-Tensor Tractography of the Auditory Neural Pathway : Clinical Usefulness in Patients with Unilateral Sensorineural Hearing Loss.

Clin Neuroradiol 2020 Mar 29;30(1):115-122. Epub 2018 Oct 29.

Department of Radiology, College of Medicine, Dong-A University, 1,3-ga, Dongdaeshin-dong, Seogu, Busan, Korea (Republic of).

Purpose: The purpose of this study was to evaluate the structural integrity of the auditory neural pathway in patients with unilateral sensorineural hearing loss using quantitative diffusion-tensor tractography.

Methods: Diffusion-tensor tractography imaging was performed using a 3T magnetic resonance imaging system to evaluate structural alterations in the auditory neural pathway of patients with unilateral sensorineural hearing loss. The two diffusion-tensor tractography parameters, fractional anisotropy and the apparent diffusion coefficient were compared between the ipsilateral side and the contralateral side in patients and controls. Additionally, correlations between the parameter values and the hearing loss level in patients were evaluated.

Results: A total of 24 sensorineural hearing loss patients (14 males; age range, 17-65 years; average age, 45.3 years) and 24 age and sex-matched control subjects were enrolled. Fractional anisotropy values on the ipsilateral and contralateral sides were significantly lower in patients than in the control group (p = 0.004 and 0.001, respectively). The differences in the apparent diffusion coefficient values for the ipsilateral and contralateral sides between the two groups were not significant (p = 0.279 and 0.248, respectively). There was an inverse relationship between fractional anisotropy and the severity of hearing impairment on the ipsilateral and contralateral sides (r = -0.519, p = 0.005 and r = -0.454, p = 0.015, respectively). No significant correlation was found between the apparent diffusion coefficient and hearing loss level on the ipsilateral and contralateral sides (r = 0.172, p = 0.380 and r = 0.131, p = 0.508, respectively).

Conclusion: Quantitative diffusion-tensor tractography can be used to detect microstructural alterations in the auditory neural pathway in sensorineural hearing loss patients with normal results in standard imaging studies.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00062-018-0733-xDOI Listing
March 2020

Shared co-expression networks in frontal cortex of the normal aged brain and schizophrenia.

Schizophr Res 2019 02 15;204:253-261. Epub 2018 Sep 15.

Department of Bio and Brain Engineering, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon 305-701, Republic of Korea. Electronic address:

Previous studies on the brain of people with schizophrenia have identified structural changes and gene expression changes, suggesting that brain aging maybe accelerated in people with schizophrenia. To better characterize gene expression profiles in schizophrenia and in the aged population we constructed co-expression networks using RNA-Seq data from frontal cortex. The first data set analysed was from 62 subjects with schizophrenia and 51 unaffected controls ranging in age from 19 to 63 years. The second separate data set was from normal control individuals ranging in age from 29 to 106 years. In the first data set, we found two co-expression modules significantly associated with schizophrenia. One was a downregulated co-expression module enriched for neuron function related genes and the other was an upregulated immune/inflammation-related module. In the second data set of normal individuals, we found seven co-expression modules significantly correlated with age. A comparison of the co-expression modules from the two data sets revealed a significant consensus in nodes associated with schizophrenia and those associated with normal aging. The results indicate that a co-expression module related to neuronal function is downregulated and an immune/inflammation related co-expression module is upregulated, and associated with cells of the blood vessels, in both schizophrenia and in normal aging. This finding adds further support to the hypothesis that there may be accelerated brain aging in schizophrenia.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.schres.2018.09.010DOI Listing
February 2019

Identification of common coexpression modules based on quantitative network comparison.

BMC Bioinformatics 2018 06 13;19(Suppl 8):213. Epub 2018 Jun 13.

Bio-Synergy Research Center, Daejeon, 34141, South Korea.

Background: Finding common molecular interactions from different samples is essential work to understanding diseases and other biological processes. Coexpression networks and their modules directly reflect sample-specific interactions among genes. Therefore, identification of common coexpression network or modules may reveal the molecular mechanism of complex disease or the relationship between biological processes. However, there has been no quantitative network comparison method for coexpression networks and we examined previous methods for other networks that cannot be applied to coexpression network. Therefore, we aimed to propose quantitative comparison methods for coexpression networks and to find common biological mechanisms between Huntington's disease and brain aging by the new method.

Results: We proposed two similarity measures for quantitative comparison of coexpression networks. Then, we performed experiments using known coexpression networks. We showed the validity of two measures and evaluated threshold values for similar coexpression network pairs from experiments. Using these similarity measures and thresholds, we quantitatively measured the similarity between disease-specific and aging-related coexpression modules and found similar Huntington's disease-aging coexpression module pairs.

Conclusions: We identified similar Huntington's disease-aging coexpression module pairs and found that these modules are related to brain development, cell death, and immune response. It suggests that up-regulated cell signalling related cell death and immune/ inflammation response may be the common molecular mechanisms in the pathophysiology of HD and normal brain aging in the frontal cortex.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/s12859-018-2193-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5998758PMC
June 2018

Room temperature operation of mid-infrared InAsSb based photovoltaic detectors with an InAlSb barrier layer grown on GaAs substrates.

Opt Express 2018 Mar;26(5):6249-6259

In this paper, InAsSb-based hetero-junction photovoltaic detector (HJPD) with an InAlSb barrier layer was grown on GaAs substrates. By using technology computer aided design (TCAD), a design of a barrier layer that can achieve nearly zero valance band offsets was accomplished. A high quality InAsSb epitaxial layer was obtained with relatively low threading dislocation density (TDD), calculated from a high-resolution X-ray diffraction (XRD) measurement. This layer showed a Hall mobility of 15,000 cm/V⋅s, which is the highest mobility among InAsSb layers with an Sb composition of around 20% grown on GaAs substrates. Temperature dependence of dark current, photocurrent response and responsivity were measured and analyzed for fabricated HJPD. HJPD showed the clear photocurrent response having a long cutoff wavelength of 5.35 μm at room temperature. It was observed that the dark current of HJPDs is dominated by the diffusion limited current at temperatures ranging from 200K to room temperature from the dark current analysis. Peak responsivity of HJPDs exhibited the 1.18 A/W and 15 mA/W for 83K and a room temperature under zero bias condition even without anti-reflection coating (ARC). From these results, we believe that HJPDs could be an appropriate PD device for future compact and low power dissipation mid-infrared on-chip sensors and imaging devices.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1364/OE.26.006249DOI Listing
March 2018

Fabrication of a vertically-stacked passive-matrix micro-LED array structure for a dual color display.

Opt Express 2017 Feb;25(3):2489-2495

We report a color tunable display consisting of two passive-matrix micro-LED array chips. The device has combined vertically stacked blue and green passive-matrix LED array chips sandwiched by a transparent bonding material. We demonstrate that vertically stacked blue and green micro-pixels are independently controllable with operation of four color modes. Moreover, the color of each pixel is tunable in the entire wavelength from the blue to green region (450 nm - 540 nm) by applying pulse-width-modulation bias voltage. This study is meaningful in that a dual color micro-LED array with a vertically stacked subpixel structure is realized.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1364/OE.25.002489DOI Listing
February 2017

Collecting, storing, and mining research data in a brain bank.

Handb Clin Neurol 2018 ;150:167-179

Stanley Medical Research Institute, Laboratory of Brain Research, Rockville, MD, United States.

The Stanley Medical Research Institute Brain Collection distributes samples from specified cohorts that contain demographically matched groups of subjects with mental illnesses such as schizophrenia, bipolar disorder, and major depression, as well as unaffected controls. The groups are matched by age, sex, race, postmortem interval, pH, side of brain, and mRNA quality. The samples are distributed coded so that all data must be returned in order to obtain the demographic information. The database contains more than 5000 individual data sets, as well as data from high-throughput microarray, sequencing, and proteomic studies. While most data were generated from the frontal cortex and hippocampus, the cerebellum has the most data sets that differ significantly between diagnostic groups and controls. The database contains interactive features and statistical tools that enable online data mining and real-time data analysis. The decrease in density of parvalbumin-positive neurons in schizophrenia, one of the most replicated findings in the field, is used to illustrate features of the brain bank. We describe how this finding can be replicated and validated in this database. We also show how the density of parvalbumin-positive neurons is correlated with markers of immune activation in the neuropathology data sets, how it is correlated with immune-related genes in a microarray data set, and how it is associated with a single-nucleotide polymorphism in the immune complement system.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/B978-0-444-63639-3.00013-XDOI Listing
August 2018

Atherosclerosis is exacerbated by chitinase-3-like-1 in amyloid precursor protein transgenic mice.

Theranostics 2018 1;8(3):749-766. Epub 2018 Jan 1.

College of Pharmacy & Medical Research Center, Chungbuk National University, Cheongju, Chungbuk 28160, Korea.

Although the important role of amyloid precursor protein (APP) in vascular diseases associated with Alzheimer's disease (AD) has been demonstrated, the underlying molecular mechanisms and physiological consequences are unclear. We aimed to evaluate vascular inflammation and atherosclerosis in Swedish mutant of human APP transgenic (APPsw-Tg) and ApoE/APPsw-Tg mice. We also aimed to explore the mechanisms underlying any changes observed in these mice compared with non-Tg controls. The transgenic and non-Tg mouse strains were subjected to partial ligation of the left carotid artery to induce atherosclerotic changes, which were measured using histological approaches, immunohistochemistry, quantitative polymerase chain reaction, and gene expression microarrays. Our results showed increased vascular inflammation, arterial wall thickness, and atherosclerosis in APPsw-Tg and ApoE/APPsw-Tg mice. We further found that the expression of chitinase-3-like-1 (Chi3l1) is increased in the APPsw-Tg mouse artery and Chi3l1 mediates endothelial cell (EC) inflammation and vascular smooth muscle cell (VSMC) activation, which in turn exacerbates atherosclerosis. In addition, using two publicly available microarray datasets from the dorsolateral prefrontal cortex of people with AD and unaffected controls as well as inflamed human umbilical vein endothelial cells, we found that Chi3l1 and associated inflammatory gene were significantly associated with AD, evaluated by co-expression network analysis and functional annotation. Knockdown of Chi3l1 in the arterial endothelium suppressed the development of atherosclerosis. We also show that microRNA 342-3p (miR-342-3p) inhibits EC inflammation and VSMC activation through directly targeting Chi3l1, and that APPsw increased Chi3l1 expression by reducing miR-342-3p expression in the arterial endothelium, promoting atherosclerosis. Our findings suggest that targeting Chi3l1 might provide new diagnostic and therapeutic strategies for vascular diseases in patients with AD.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.7150/thno.20183DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5771091PMC
December 2018

Spontaneous Regression of an Intracranial Aneurysm Following Remote Aneurysm Clipping: Evaluation with High-Resolution Vessel Wall MRI.

Cardiovasc Intervent Radiol 2018 Apr 19;41(4):660-663. Epub 2017 Dec 19.

Department of Radiology, Dong-A University Hospital, 3-1Ga, Dongdaeshin-Dong, Busan, 602-715, Republic of Korea.

Spontaneous regression of an unruptured aneurysm is very rare. We present a case of a 64-year-old woman with an unruptured cerebral aneurysm in which spontaneous regression occurred after contralateral clipping. High-resolution magnetic resonance imaging showed that the aneurysm had decreased in size and there was no evidence of thrombus. Level of Evidence Case, Level IV.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00270-017-1864-1DOI Listing
April 2018

Presenilin Mutation Suppresses Lung Tumorigenesis via Inhibition of Peroxiredoxin 6 Activity and Expression.

Theranostics 2017 1;7(15):3624-3637. Epub 2017 Sep 1.

College of Pharmacy and Medical Research Center, Chungbuk National University, 12, Gaeshin-dong, Heungduk-gu, Cheongju, Chungbuk 361-763, Republic of Korea.

Some epidemiological studies suggest an inverse correlation between cancer incidence and Alzheimer's disease (AD). In this study, we demonstrated experimental evidences for this inverse relationship. In the co-expression network analysis using the microarray data and GEO profile of gene expression omnibus data analysis, we showed that the expression of peroxiredoxin 6 (PRDX6), a tumor promoting protein was significantly increased in human squamous lung cancer, but decreased in mutant presenilin 2 (PS2) containing AD patient. We also found in animal model that mutant PS2 transgenic mice displayed a reduced incidence of spontaneous and carcinogen-induced lung tumor development compared to wildtype transgenic mice. Agreed with network and GEO profile study, we also revealed that significantly reduced expression of PRDX6 and activity of iPLA2 in these animal models. PS2 mutations increased their interaction with PRDX6, thereby increasing iPLA2 cleavage via increased γ-secretase leading to loss of PRDX6 activity. However, knockdown or inhibition of γ-secretase abolished the inhibitory effect of mutant PSs. Moreover, PS2 mutant skin fibroblasts derived from patients with AD showed diminished iPLA2 activity by the elevated γ-secretase activity. Thus, the present data suggest that PS2 mutations suppress lung tumor development by inhibiting the iPLA2 activity of PRDX6 via a γ-secretase cleavage mechanism and may explain the inverse relationship between cancer and AD incidence.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.7150/thno.21408DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5667337PMC
June 2018

Reduced Graphene Oxide/LiI Composite Lithium Ion Battery Cathodes.

Nano Lett 2017 11 20;17(11):6893-6899. Epub 2017 Oct 20.

School of Chemical Engineering, Chonbuk National University , 567 Baekje-daero, Deokjin-gu, Jeonju-si, Jeollabuk-do 54896, Republic of Korea.

Li-iodine chemistry is of interest for electrochemical energy storage because it has been shown to provide both high power and high energy density. However, Li-iodine batteries are typically formed using Li metal and elemental iodine, which presents safety and fabrication challenges (e.g., the high vapor pressure of iodine). These disadvantages could be circumvented by using LiI as a starting cathode. Here, we present fabrication of a reduced graphene oxide (rGO)/LiI composite cathode, enabling for the first time the use of LiI as the Li-ion battery cathode. LiI was coated on rGO by infiltration of an ethanolic solution of LiI into a compressed rGO aerogel followed by drying. The free-standing rGO/LiI electrodes show stable long-term cycling and good rate performance with high specific capacity (200 mAh g at 0.5 C after 100 cycles) and small hysteresis (0.056 V at 1 C). Shuttling was suppressed significantly. We speculate the improved electrochemical performance is due to strong interactions between the active materials and rGO, and the reduced ion and electron transport distances provided by the three-dimensional structured cathode.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.nanolett.7b03290DOI Listing
November 2017

Monolithic integration of AlGaInP-based red and InGaN-based green LEDs via adhesive bonding for multicolor emission.

Sci Rep 2017 09 4;7(1):10333. Epub 2017 Sep 4.

School of Electrical Engineering and Computer Science, Gwangju Institute of Science and Technology (GIST), 123 Cheomdangwagi-ro, Buk-gu, Gwangju, 61005, Korea.

In general, to realize full color, inorganic light-emitting diodes (LEDs) are diced from respective red-green-blue (RGB) wafers consisting of inorganic crystalline semiconductors. Although this conventional method can realize full color, it is limited when applied to microdisplays requiring high resolution. Designing a structure emitting various colors by integrating both AlGaInP-based and InGaN-based LEDs onto one substrate could be a solution to achieve full color with high resolution. Herein, we introduce adhesive bonding and a chemical wet etching process to monolithically integrate two materials with different bandgap energies for green and red light emission. We successfully transferred AlGaInP-based red LED film onto InGaN-based green LEDs without any cracks or void areas and then separated the green and red subpixel LEDs in a lateral direction; the dual color LEDs integrated by the bonding technique were tunable from the green to red color regions (530-630 nm) as intended. In addition, we studied vertically stacked subpixel LEDs by deeply analyzing their light absorption and the interaction between the top and bottom pixels to achieve ultra-high resolution.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41598-017-11239-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5583240PMC
September 2017

InAs/GaAs quantum dot infrared photodetector on a Si substrate by means of metal wafer bonding and epitaxial lift-off.

Opt Express 2017 Jul;25(15):17562-17570

We report the fabrication of quantum dot infrared photodetectors (QDIPs) on silicon (Si) substrates by means of metal wafer bonding and an epitaxial lift-off process. According to the photoluminescence (PL) and x-ray diffraction measurements, the QDIP layer was transferred onto the Si substrate without degradation of the crystal quality or residual strain. In addition, from the PL results, we found that an optical cavity was formed because Pt/Au of the bonding material was served as the back mirror and the facet of the GaAs/air was served as the front mirror. The device performance capabilities were directly compared and peak responsivity was enhanced by nearly twofold from 0.038 A/W to 0.067 A/W.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1364/OE.25.017562DOI Listing
July 2017

Interleukin-32α Inhibits Endothelial Inflammation, Vascular Smooth Muscle Cell Activation, and Atherosclerosis by Upregulating Timp3 and Reck through suppressing microRNA-205 Biogenesis.

Theranostics 2017 1;7(8):2186-2203. Epub 2017 Jun 1.

College of Pharmacy & Medical Research Center, Chungbuk National University, Cheongju, Chungbuk 28160, Korea.

Interleukin-32 (IL-32) is a multifaceted cytokine that promotes inflammation and regulates vascular endothelial cell behavior. Although some IL-32 isoforms have been reported to contribute to vascular inflammation and atherosclerosis, the functional role of IL-32α in vascular inflammation and atherogenesis has not been studied. IL-32α function was assessed in cells with transient IL-32α overexpression or treated with recombinant human IL-32α by western blotting and mRNA expression analysis. Vascular smooth muscle cell (VSMC) proliferation and migration was examined by BrdU incorporation and wound healing assays, respectively. In addition, the participation of IL-32α on vascular inflammation, arterial wall thickening, and atherosclerosis was monitored in human IL-32α transgenic (hIL-32α-Tg) mice with or without ApoE knockout (ApoE /hIL-32α-Tg). Our analyses showed that IL-32α suppresses genes involved in the inflammatory and immune responses and cell proliferation, and by limiting matrix metalloproteinase (MMP) function. , administration of hIL-32α inhibited vascular inflammation and atherosclerosis in hIL-32α-Tg and ApoE /hIL-32α-Tg mice. Subsequent microarray and analysis also revealed a marked decreased in inflammatory gene expression in hIL-32α-Tg mice. Collectively, our studies demonstrated that IL-32α upregulates the atheroprotective genes Timp3 and Reck by downregulating microRNA-205 through regulation of the Rprd2-Dgcr8/Ddx5-Dicer1 biogenesis pathway. Our findings provide the first direct evidence that IL-32α is an anti-inflammatory and anti-atherogenic cytokine that may be useful as a diagnostic and therapeutic protein in atherosclerosis.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.7150/thno.18407DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5505053PMC
March 2018

Parkin Knockout Inhibits Neuronal Development via Regulation of Proteasomal Degradation of p21.

Theranostics 2017 12;7(7):2033-2045. Epub 2017 May 12.

College of Pharmacy and Medical Research Center, Chungbuk National University, 194-31, Osongsaengmyeong 1-ro, Osong-eup, Cheongwon-gun, Chungbuk, Republic of Korea, 361-951.

PARK2 encodes for the E3 ubiquitin ligase parkin and is implicated in the development of Parkinson's disease (PD). Although the neuroprotective role of parkin is well known, the mechanism of PARK2's function in neural stem differentiation has not yet been thoroughly studied. Co-expressions network analysis showed that synaptosomal-associated protein 25 (SNAP-25) and brain-derived neurotrophic factor (BDNF) were positively correlated with parkin, but negatively correlated with p21 in human patient brain. We investigated a link between the ubiquitin E3 ligase parkin and proteasomal degradation of p21 for the control of neural stem cell differentiation. We found that the neurogenesis was lowered in PARK2 knockout (KO) mice compared with non-tg mice. Expression of the marker protein for neural cell differentiation such as class III beta tubulin (TUBBIII), glial fibrillary acidic protein (GFAP) and neurofilament, as well as SNAP25 and BDNF, was down regulated in PARK2 KO mice. Associated with the loss of differentiation function, p21 protein was highly accumulated in the neural stem cells of PARK2 KO mice. We discovered that p21 directly binds with parkin and is ubiquitinated by parkin which resulted in the loss of cell differentiation ability. Introduction of p21 shRNA in PARK2 KO mice significantly rescued the differentiation efficacy as well as SNAP25 and BDNF expression. c-Jun N-terminal kinase (JNK) pathway is implicated in neurogenesis and p21 degradation. We also defined the decreased p21 ubiquitination and differentiation ability were reversed after treatment with JNK inhibitor, SP600125 in PARK2 KO mice derived neural stem cells. Thus, the present study indicated that parkin knockout inhibits neural stem cell differentiation by JNK-dependent proteasomal degradation of p21.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.7150/thno.19824DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5485421PMC
March 2018

Safety of coil occlusion of the parent artery for endovascular treatment of anterior communicating artery aneurysm.

Neuroradiol J 2016 Jun 17;29(3):201-7. Epub 2016 Mar 17.

Department of Radiology, Dong-A University Hospital, Republic of Korea.

Many studies lay emphasis on the clinical importance of perforating branches of the anterior communicating artery (ACoA) and report that vascular damage of the perforators from ACoA aneurysm during surgery cause subsequent postoperative amnesia. The purpose of our study was to analyze the safety of parent artery occlusion for ACoA aneurysm coiling based on the anatomical features of the ACoA complex in 13 patients with 13 ACoA aneurysms. All patients underwent coiling of the aneurysm sac and ACoA. Aneurysm characteristics including size, dome-to-neck ratio, anterior/posterior orientation of the aneurysm dome with respect to the axis of the pericallosal artery, location of the aneurysm neck with respect to the A1-A2 segment of the anterior cerebral artery (ACA) or the ACoA, and the presence of hypoplasia/aplasia of A1 segment were assessed. The aneurysm neck was located directly on the ACoA in five aneurysms (38%), whereas eight (62%) had the neck located at the A1-A2 junction. Of the five patients whose aneurysm neck was located in the ACoA, four patients had infarcts in the basal forebrain. Three of the patients complained of amnesia. None of the aneurysms with the neck located at the A1-A2 junction were associated with infarction. There has been little evidence thus far that parent vessel occlusion of ACoA aneurysms is a safe method for the treatment of aneurysms. Patients with the aneurysm neck located at the A1-A2 junction and without A1 aplasia, who were treated with aneurysm sac and ACoA embolism, were potentially safe.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1177/1971400916639604DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4977924PMC
June 2016

Ultra-high-throughput Production of III-V/Si Wafer for Electronic and Photonic Applications.

Sci Rep 2016 Feb 11;6:20610. Epub 2016 Feb 11.

Korea Institute of Science and Technology (KIST), Hwarangno 14-gil 5, Seongbuk-gu, Seoul, 136-791, Korea.

Si-based integrated circuits have been intensively developed over the past several decades through ultimate device scaling. However, the Si technology has reached the physical limitations of the scaling. These limitations have fuelled the search for alternative active materials (for transistors) and the introduction of optical interconnects (called "Si photonics"). A series of attempts to circumvent the Si technology limits are based on the use of III-V compound semiconductor due to their superior benefits, such as high electron mobility and direct bandgap. To use their physical properties on a Si platform, the formation of high-quality III-V films on the Si (III-V/Si) is the basic technology ; however, implementing this technology using a high-throughput process is not easy. Here, we report new concepts for an ultra-high-throughput heterogeneous integration of high-quality III-V films on the Si using the wafer bonding and epitaxial lift off (ELO) technique. We describe the ultra-fast ELO and also the re-use of the III-V donor wafer after III-V/Si formation. These approaches provide an ultra-high-throughput fabrication of III-V/Si substrates with a high-quality film, which leads to a dramatic cost reduction. As proof-of-concept devices, this paper demonstrates GaAs-based high electron mobility transistors (HEMTs), solar cells, and hetero-junction phototransistors on Si substrates.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/srep20610DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4750074PMC
February 2016

Thrombectomy using a stent retriever with artificially induced vertebral artery vasospasm in a patient with acute basilar artery occlusion: a case report.

Neuroradiol J 2016 Feb 17;29(1):90-2. Epub 2015 Dec 17.

Department of Neurosurgery, Busan-Ulsan Regional Cardio-Cerebrovascular Diseases Center, Republic of Korea.

An acute basilar artery occlusion is not an uncommon cause of stroke. It represents 6-10% of large vessel strokes and has been associated with poor clinical outcomes. Multimodal treatments have been introduced to recanalise a basilar artery occlusion successfully. However, all mechanical thrombectomy devices are not always usable in an emergent situation. We present a case of basilar artery occlusion treated with a stent retriever assisted by a vertebral artery vasospasm. We attempted thrombectomy with a stent retriever several times. However, the captured thrombus was not pulled out and migrated to the distal basilar artery and posterior cerebral artery due to anterograde flow of the vertebral artery. We carefully advanced the catheter into the distal vertebral artery and generated a vasospasm. The vertebral artery vasospasm reduced the forward flow significantly like a balloon-guided catheter. The thrombus was pulled out with the stent.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1177/1971400915620438DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4978337PMC
February 2016

Mismatch of delayed perfusion volume between TTP and Tmax map of perfusion MRI.

Clin Imaging 2016 Jan-Feb;40(1):63-7. Epub 2015 Oct 21.

Department of Radiology, Dong-A University Medical Center, 1,3-ga, Dongdaeshin-dong, Seo-gu, Busan 602-715, Korea.

Objective: To look for another set of parameters to predict the change in infarct size in acute stroke patients with a perfusion-weighted imaging (PWI)-diffusion-weighted imaging (DWI) mismatch.

Materials And Methods: We reviewed 54 patients who had PWI-DWI mismatch and vascular occlusion on initial MRI and no recanalization of occluded vessel.

Results: Time-to-peak and time-to-max (TTP-Tmax) perfusion mismatch volume was independently significant as a correlate of infarct volume change (P=.004).

Conclusions: The finding of a large TTP-Tmax perfusion delay mismatch volume in patients with acute stroke who have a PWI-DWI mismatch on an initial MRI may predict that the infarct volume will not increase despite persistent vascular occlusion.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.clinimag.2015.10.005DOI Listing
August 2016

InGaP/GaAs heterojunction phototransistors transferred to a Si substrate by metal wafer bonding combined with epitaxial lift-off.

Opt Express 2015 Oct;23(21):26888-94

We report fabrication and optical characteristics of an InGaP/GaAs heterojunction phototransistor (HPT) transferred to a Si substrate by a metal wafer bonding (MWB) and epitaxial lift-off (ELO) process at room temperature. An intermediate Pt/Au double layer between the HPT layer and Si provided a very smooth surface by which to achieve the MWB, and excellent durability against the acid solution during the ELO process. These processes were observed using scanning electron microscope (SEM) and atomic force microscopy (AFM). While the results on a low temperature photoluminescence (LTPL) signal and high resolution x-ray diffraction (HRXRD) rocking curve of the bonded device film implied a defect-free bonding, a very low collector dark current of the fabricated HPT was observed. The optical performance of a bonded InGaP/GaAs HPT on Si, operating at 635 nm wavelength is also investigated.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1364/OE.23.026888DOI Listing
October 2015