Daeyoung Oh

CHA University, Sŏul, Seoul, South Korea

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Publications (11)37.69 Total impact

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    ABSTRACT: The risk of suicide is disproportionately high among people diagnosed with schizophrenia or schizophreniform disorder. Brain imaging studies have shown a few relationships between neuroanatomy and suicide. This study examines the relationship between alterations in brain white matter (WM) and suicidal behavior in people with schizophrenia or schizophreniform disorder. The study participants were 56 patients with schizophrenia or schizophreniform disorder, with (n=15) and without (n=41) a history of suicide attempts. Fractional anisotropy (FA) values were compared between suicide attempters and non-attempters using Tract-Based Spatial Statistics (TBSS). Attempters showed significantly higher FA values than non-attempters in the left corona radiata, the superior longitudinal fasciculus, the posterior limb and retrolenticular part of the internal capsule, the external capsule, the insula, the posterior thalamic radiation, the cerebral peduncle, the sagittal stratum, and temporal lobe WM. Scores of the picture arrangement test showed a significant positive correlation with FA values of the right corona radiata, the right superior longitudinal fasciculus, the body of the corpus callosum, and the left corona radiata in attempters but not in non-attempters. These findings suggest that fronto-temporo-limbic circuits can be associated mainly with suicidal behavior in people with schizophrenia or schizophreniform disorder.
    No preview · Article · Jan 2016
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    ABSTRACT: Reprogramming of somatic cells into induced pluripotent stem cells (iPSCs) provides a valuable opportunity to study neurodevelopmental and neurodegenerative psychiatric diseases by offering an unlimited source for patient-specific neuronal and glial cells. The present review focuses on the recent advancements in modeling psychiatric disorders such as Phelan-McDermid syndrome, Timothy syndrome, Rett syndrome, schizophrenia, bipolar disorder, and dementia. The treatment effects identified in studies on iPSCs using known therapeutic compounds are also summarized in this review. Here we discuss validation of cellular models and explore iPSCs as a novel drug screening tool. Although there are several limitations associated with the current methods used to study mental disorders, using iPSCs as a model system provides the advantage of rewinding and reviewing the development and degeneration of human neural cells.
    Preview · Article · Jan 2016 · Psychiatry investigation
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    ABSTRACT: Synaptic adhesion molecules regulate synapse development and plasticity through mechanisms that include trans-synaptic adhesion and recruitment of diverse synaptic proteins. We found that the immunoglobulin superfamily member 11 (IgSF11), a homophilic adhesion molecule that preferentially expressed in the brain, is a dual-binding partner of the postsynaptic scaffolding protein PSD-95 and AMPA glutamate receptors (AMPARs). IgSF11 required PSD-95 binding for its excitatory synaptic localization. In addition, IgSF11 stabilized synaptic AMPARs, as determined by IgSF11 knockdown-induced suppression of AMPAR-mediated synaptic transmission and increased surface mobility of AMPARs, measured by high-throughput, single-molecule tracking. IgSF11 deletion in mice led to the suppression of AMPAR-mediated synaptic transmission in the dentate gyrus and long-term potentiation in the CA1 region of the hippocampus. IgSF11 did not regulate the functional characteristics of AMPARs, including desensitization, deactivation or recovery. These results suggest that IgSF11 regulates excitatory synaptic transmission and plasticity through its tripartite interactions with PSD-95 and AMPARs.
    Full-text · Article · Nov 2015 · Nature Neuroscience
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    ABSTRACT: Fluoxetine, a serotonin-selective reuptake inhibitor, exerts antidepressant and antianxiety effects on major depressive and anxiety disorders. Previous studies suggest that treatment with fluoxetine influences the expression of various proteins that are involved in proliferation, differentiation, and apoptosis in the neuronal cells of the brain. However, many aspects of the molecular pathways that modulate antidepressant action are not well understood. Here, with the aim of identifying proteins involved in antidepressant action, we examined the protein expression profile of human embryonic carcinoma (NCCIT) cells in response to fluoxetine treatment using proteomic techniques such as two-dimensional gel electrophoresis and matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS). We found several upregulated and downregulated proteins in fluoxetine-treated NCCIT cells, and then biochemically confirmed the increased expression of heat shock protein 90 and 14-3-3ε, which play an essential role in many cellular mechanisms including cell cycle control and other signaling pathways. Our data suggest that the regulated expression of heat shock protein 90, 14-3-3ε, and other identified proteins may be associated with the therapeutic action of fluoxetine.
    No preview · Article · Dec 2014 · Neuroreport
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    ABSTRACT: Objective Antidepressants Modulate Neuronal Plasticity. Tianeptine, An Atypical Antidepressant, Might Be Involved In The Restoration Of Neuronal Plasticity; It Primarily Enhances The Synaptic Reuptake Of Serotonin. Ncam140 Is Involved In Neuronal Development Processes, Synaptogenesis And Synaptic Plasticity. We Investigated The Effect Of Tianeptine On The Expression Of Ncam140 And Its Downstream Signaling Molecule In The Human Neuroblastoma Cell Line Sh-sy5y. Methods NCAM protein expression was measured in human neuroblastoma SH-SY5Y cells that were cultivated in serum-free media and treated with 0, 10, or 20 µM tianeptine for 6, 24, or 72 hours. NCAM140 expression in the tianeptine treatment group was confirmed by Western blot, and quantified through measurement of band intensity by absorbance. CREB and pCREB expression was identified after treatment with 20 µM tianeptine for 6, 24, and 72 hours by Western blot. Results Compared to cells treated for 6 hours, cells treated with 0 or 10 µM tianeptine for 72 hours showed a significant increase in NCAM140 expression and cells treated with 20 µM tianeptine showed a significant increase after 24 and 72 hours. The pCREB level in cells treated with 20 µM tianeptine increased in time-dependent manner. Conclusion Our findings indicated that the tianeptine antidepressant effect may occur by induction of NCAM140 expression and CREB phosphorylation.
    Preview · Article · Jul 2014 · Psychiatry investigation
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    Daeyoung Oh · Daeho Kim

    Preview · Article · Jul 2014 · Psychiatry investigation
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    Ahyoung Paik · Daeyoung Oh · Daeho Kim
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    ABSTRACT: Similar to substance use disorder, patients with Internet addiction disorder (IAD) show excessive use, tolerance and withdrawal symptoms. We report a case of a patient with withdrawal psychosis who showed persecutory delusion and disorganized behaviors in addition to common withdrawal symptoms such as agitation and irritability. A 25-year-old male developed a full-blown psychotic episode within one day after discontinuing an Internet game that he had been playing for at least eight hours a day for two years. Upon admission, he had no abnormal brain imaging findings and laboratory tests. With antipsychotic medication (quetiapine up to 800 mg), his psychotic symptoms rapidly subsided and after four days of treatment, he no longer showed any signs of psychosis. This case report suggests that brief psychosis can develop during withdrawal from long-term excessive use of an Internet and the central pathology beneath the IAD is more likely a form of addiction than impulse control.
    Preview · Article · Apr 2014 · Psychiatry investigation
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    ABSTRACT: Previous human postmortem studies have shown that expression of glutamate transporters (SLC1A2 and SLC1A3) and gamma-aminobutyric acid-synthesizing enzyme [glutamic acid decarboxylase 1 (GAD1)] are reduced in the dorsolateral prefrontal cortex (dlPFC) in subjects with major depressive disorder (MDD). However, no studies have explored the association between these two molecules and its related biological processes in MDD because of limited postmortem sample availability. Data sharing using the Stanley neuropathology consortium integrative database (SNCID), a web-based tool that integrates datasets from the same postmortem brain samples, allowed us to reanalyze existing postmortem data efficiently. We found two datasets where the mRNA levels of GAD1 and SLC1A2 in subregions of the dlPFC were significantly and marginally lower in subjects with MDD (n = 15) than in controls (n = 15) (p = 0.045 and 0.057, respectively). In addition, there was a positive correlation between these two molecules (n = 30, p < 0.05). Spearman's rank correlation analysis using all available datasets revealed that the expression levels of both GAD1 and SLC1A2 mRNAs were commonly correlated with the expression levels of several neuropathological markers in the dlPFC in all of the SNCID subjects (n = 60, p < 0.001). Most of these markers are known to be involved in the RAF/MEK/ERK signal transduction pathway. This exploratory study provides an initial step for future studies to investigate an association between the reductions in SLC1A2 and GAD1 mRNA expression and their relation to the attenuation of the RAF/MEK/ERK signaling pathway in the dlPFC in MDD. The integration of the existing archival data may shed light on one important aspect of the pathophysiology of MDD.
    Full-text · Article · Mar 2014 · Journal of Neural Transmission
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    ABSTRACT: Dendritic arborization is important for neuronal development as well as the formation of neural circuits. Rac1 is a member of the Rho GTPase family which serves as regulators of neuronal development. BCR (breakpoint cluster region) is a Rac1 GTPase-activating protein which is abundantly expressed in the central nervous system. Here we show that BCR plays a key role in neuronal development. Dendritic arborization and actin polymerization were attenuated by overexpression of BCR in hippocampal neurons. Knockdown of BCR using specific shRNAs increased the dendritic arborization as well as actin polymerization. The number of dendrites of null mutant BCR-/- mice was considerably increased compared with wild type. The function of the BCR GTPase-activating domain could be controlled by PTPRT (protein tyrosine phosphatase receptor T) expressed principally in the brain. We demonstrate that tyrosine 177 of BCR was the main target of PTPRT and the BCR mutant mimicking dephosphorylation of tyrosine 177 alleviated the attenuation of dendritic arborization. Additionally the attenuated dendritic arborization by BCR overexpression was relieved upon co-expression of PTPRT. When PTPRT was knocked down by specific shRNA, the dendritic arborization was significantly reduced. The function of the BCR GTPase-activating domain was controlled by means of conversions between the intra- and inter-molecular interactions that are finely regulated through the dephosphorylation of a specific tyrosine residue by PTPRT. We thus show conclusively that BCR is a novel substrate of PTPRT and that BCR is involved in the regulation of neuronal development via control of the BCR GTPase-activating domain function by PTPRT.
    Full-text · Article · Jul 2012 · Journal of Cell Science
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    ABSTRACT: Rho family small GTPases are important regulators of neuronal development. Defective Rho regulation causes nervous system dysfunctions including mental retardation and Alzheimer's disease. Rac1, a member of the Rho family, regulates dendritic spines and excitatory synapses, but relatively little is known about how synaptic Rac1 is negatively regulated. Breakpoint cluster region (BCR) is a Rac GTPase-activating protein known to form a fusion protein with the c-Abl tyrosine kinase in Philadelphia chromosome-positive chronic myelogenous leukemia. Despite the fact that BCR mRNAs are abundantly expressed in the brain, the neural functions of BCR protein have remained obscure. We report here that BCR and its close relative active BCR-related (ABR) localize at excitatory synapses and directly interact with PSD-95, an abundant postsynaptic scaffolding protein. Mice deficient for BCR or ABR show enhanced basal Rac1 activity but only a small increase in spine density. Importantly, mice lacking BCR or ABR exhibit a marked decrease in the maintenance, but not induction, of long-term potentiation, and show impaired spatial and object recognition memory. These results suggest that BCR and ABR have novel roles in the regulation of synaptic Rac1 signaling, synaptic plasticity, and learning and memory, and that excessive Rac1 activity negatively affects synaptic and cognitive functions.
    Full-text · Article · Oct 2010 · The Journal of Neuroscience : The Official Journal of the Society for Neuroscience
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    Wonjun Kim · Jaeho Lee · Minjin Kim · Daeyoung Oh · Changick Kim
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    ABSTRACT: This paper presents a method for recognizing human actions from a single query action video. We propose an action recognition scheme based on the ordinal measure of accumulated motion, which is robust to variations of appearances. To this end, we first define the accumulated motion image (AMI) using image differences. Then the AMI of the query action video is resized to a N×Nsubimage by intensity averaging and a rank matrix is generated by ordering the sample values in the sub-image. By computing the distances from the rank matrix of the query action video to the rank matrices of all local windows in the target video, local windows close to the query action are detected as candidates. To find the best match among the candidates, their energy histograms, which are obtained by projecting AMI values in horizontal and vertical directions, respectively, are compared with those of the query action video. The proposed method does not require any preprocessing task such as learning and segmentation. To justify the efficiency and robustness of our approach, the experiments are conducted on various datasets.
    Preview · Article · Feb 2010 · EURASIP journal on advances in signal processing

Publication Stats

86 Citations
37.69 Total Impact Points

Institutions

  • 2014-2016
    • CHA University
      • Department of Psychiatry
      Sŏul, Seoul, South Korea
    • Hanyang University
      • College of Medicine
      Sŏul, Seoul, South Korea
  • 2010-2012
    • Korea Advanced Institute of Science and Technology
      • Department of Biological Sciences
      Sŏul, Seoul, South Korea