Publications by authors named "Joonhyuk Choi"

14 Publications

  • Page 1 of 1

Giant Intradiploic Epidermoid Cyst in the Occipital Bone: A Case Report.

Brain Tumor Res Treat 2021 Apr;9(1):21-25

Department of Pathology, Yeungnam University Hospital, Yeungnam University College of Medicine, Daegu, Korea.

Epidermoid cysts are uncommon intracranial tumors. As one of the extradural types of epidermoid cysts, intradiploic epidermoid cysts are even rarer tumors and occur in any part of the skull. We herein report a rare case of a giant intradiploic epidermoid cyst of the occipital bone. A 57-year-old woman presented with a 1-year history of localized headache in the occipital area. CT and MRI showed an extradural mass measuring 50×70 mm in the occipital bone with bony destruction. The patient underwent surgical resection. The tumor was completely removed with its capsule. There was no extension to the intradural space. The pathological report confirmed that the tumor was an epidermoid cyst. Follow-up MRI 24 months after the operation showed no recurrence. The headache was well controlled without any medications. We report a rare case of intradiploic epidermoid cyst with clinical and radiologic features and surgical treatment. It is important to consider this diagnosis for a patient with persistent regional headache with or without a growing scalp mass.
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http://dx.doi.org/10.14791/btrt.2021.9.e3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8082287PMC
April 2021

Extremely delayed solitary cerebral metastasis in patient with T1N0M0 renal cell carcinoma after radical nephrectomy: Case report and literature review.

Medicine (Baltimore) 2021 Apr;100(15):e25586

Department of Pathology, Yeungnam University Hospital, Yeungnam University College of Medicine Daegu, Republic of Korea.

Rationale: Although renal cell carcinoma (RCC) is one of the common origins of brain metastasis, few cases of extremely delayed brain metastasis from RCC, more than 10 years after nephrectomy, have been reported. We present a rare case of extremely delayed brain metastasis from RCC, also performed a literature review to increase knowledge of the characteristics for extremely delayed brain metastasis from RCC.

Patient Concerns: A 72-year-old man presented with right-sided hemiplegia and dysarthria. The patient had a history of radical nephrectomy for RCC with stage T1N0M0 15 years earlier.

Diagnosis: Magnetic resonance imaging with contrast revealed a 2-cm sized non-homogenous enhanced mass in the left frontal lobe with peritumoral edema. The pathological examination after surgery reported metastatic clear cell RCC.

Interventions: A craniotomy for removal of the mass was performed at the time of diagnosis. Stereotactic radiosurgery was performed for the tumor bed 3 weeks after craniotomy, and then, chemotherapy was started 2 months after the SRS.

Outcomes: Metastasis progressed to multiple organs 6 months after the craniotomy. The patient chose a hospice and no longer visited the hospital.

Lessons: In cases with a history of nephrectomy for RCC, long period follow-up is necessary for monitoring RCC brain metastasis and pathologic diagnosis should be confirmed.
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http://dx.doi.org/10.1097/MD.0000000000025586DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8052049PMC
April 2021

Defect-Passivating Organic/Inorganic Bicomponent Hole-Transport Layer for High Efficiency Metal-Halide Perovskite Device.

ACS Appl Mater Interfaces 2020 Sep 28;12(36):40310-40317. Epub 2020 Aug 28.

Department of Organic and Nano Engineering, Hanyang University, Seoul 04763, Korea.

In this work, we introduce a bicomponent hole-transport layer, composed of inorganic NiO and a donor-acceptor-donor (D-A-D)-structured organic small molecule, for p-i-n planar perovskite photovoltaic (PV) cells. The newly designed D-A-D organic hole-transporting material (HTM), (4',4‴-(1,3,4-oxadiazole-2,5-diyl)bis(,-bis(4-methoxyphenyl)-[1,1'-biphenyl]-4-amine)), is shown to be an efficient HTM without a dopant, and methoxy functional units, further introduced to the molecules, are confirmed to be beneficial to passivate the defects in the perovskite, which improves the crystallinity of perovskite and suppresses the nonradiative recombination in the devices, consequently enhancing the performances of PV cells (over 20% efficiency from p-i-n architecture). Furthermore, the decreased defect sites along with the UV-blocking property of the HTM in p-i-n architecture are advantageous in improving the stability of the PV devices.
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http://dx.doi.org/10.1021/acsami.0c09784DOI Listing
September 2020

Mitochondrial volume fraction and translation duration impact mitochondrial mRNA localization and protein synthesis.

Elife 2020 08 7;9. Epub 2020 Aug 7.

Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, United States.

Mitochondria are dynamic organelles that must precisely control their protein composition according to cellular energy demand. Although nuclear-encoded mRNAs can be localized to the mitochondrial surface, the importance of this localization is unclear. As yeast switch to respiratory metabolism, there is an increase in the fraction of the cytoplasm that is mitochondrial. Our data point to this change in mitochondrial volume fraction increasing the localization of certain nuclear-encoded mRNAs to the surface of the mitochondria. We show that mitochondrial mRNA localization is necessary and sufficient to increase protein production to levels required during respiratory growth. Furthermore, we find that ribosome stalling impacts mRNA sensitivity to mitochondrial volume fraction and counterintuitively leads to enhanced protein synthesis by increasing mRNA localization to mitochondria. This points to a mechanism by which cells are able to use translation elongation and the geometric constraints of the cell to fine-tune organelle-specific gene expression through mRNA localization.
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http://dx.doi.org/10.7554/eLife.57814DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7413667PMC
August 2020

Role of mitochondrial fission-related genes in mitochondrial morphology and energy metabolism in mouse embryonic stem cells.

Redox Biol 2020 09 30;36:101599. Epub 2020 May 30.

Department of Stem Cell and Regenerative Biotechnology, Konkuk Institute of Technology, Konkuk University, Seoul, Republic of Korea. Electronic address:

Mitochondria, the major organelles that produce energy for cell survival and function, dynamically change their morphology via fusion and fission, a process called mitochondrial dynamics. The details of the underlying mechanism of mitochondrial dynamics have not yet been elucidated. Here, we aimed to investigate the function of mitochondrial fission genes in embryonic stem cells (ESCs). To this end, we generated homozygous knockout ESC lines, namely, Fis1, Mff, and Dnm1l ESCs, using the CRISPR-Cas9 system. Interestingly, the Fis1, Mff, and Dnm1l ESCs showed normal morphology, self-renewal, and the ability to differentiate into all three germ layers in vitro. However, transmission electron microscopy showed a significant increase in the cytoplasm to nucleus ratio and mitochondrial elongation in Dnm1l ESCs, which was due to incomplete fission. To assess the change in metabolic energy, we analyzed oxidative phosphorylation (OXPHOS), glycolysis, and the intracellular ATP concentration. The ESC knockout lines showed an increase in OXPHOS, decrease in glycolysis, and an increase in intracellular ATP concentration, which was related to mitochondrial elongation. In particular, the Dnm1l knockout most significantly affected mitochondrial morphology, energy metabolism, and ATP production in ESCs. Furthermore, RNA sequencing and gene ontology analysis showed that the differentially expressed genes in Mff ESCs were distinct from those in Dnm1l or Fis1 ESCs. In total, five metabolism-related genes, namely, Aass, Cdo1, Cyp2b23, Nt5e, and Pck2, were expressed in all three knockout ESC lines, and three of them were associated with regulation of ATP generation.
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http://dx.doi.org/10.1016/j.redox.2020.101599DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7286981PMC
September 2020

Inhibition of neural stem cell aging through the transient induction of reprogramming factors.

J Comp Neurol 2021 Feb 28;529(3):595-604. Epub 2020 Jun 28.

Department of Stem Cell and Regenerative Biotechnology, KU Institute of Science and Technology, Konkuk University, Seoul, Republic of Korea.

Adult stem cells age during long-term in vitro culture, and neural stem cells (NSCs), which can self-renew and differentiate into neurons and glial cells, also display reduced differentiation potential after repeated passaging. However, the mechanistic details underlying this process remain unclear. In this study, we found that long-term in vitro culture of NSCs resulted in aging-related upregulation of inflammatory- and endoplasmic reticulum (ER) stress-related genes, including the proinflammatory cytokines interleukin (IL)1β and IL6, the senescence-associated enzyme matrix metallopeptidase 13 (MMP13), and the ER stress-responsive transcription factor activating transcription factor 4 (ATF4) and C/EBP homologous protein (CHOP). However, the cyclic and transient induction of four reprogramming factors (POU domain, class 5, transcription factor 1, also known as octamer-binding transcription factor 4; SRY [sex determining region Y]-box 2; Kruppel-like factor 4; and myelocytomatosis oncogene; collectively referred to as OSKM) can inhibit NSC aging, as indicated by the decreased expression of the inflammatory and ER stress-related genes. We used ROSA-4F NSCs, which express OSKM from only one allele, to minimize the potential for full reprogramming or tumor formation during NSC rejuvenation. We expect that this novel rejuvenation method will enhance the potential of NSCs as a clinical approach to the treatment of neurological diseases.
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http://dx.doi.org/10.1002/cne.24967DOI Listing
February 2021

Calvarial Tuberculosis Presenting with Skin Defect in an Elderly Patient.

World Neurosurg 2020 08 16;140:267-270. Epub 2020 May 16.

Department of Pathology, Yeungnam University Hospital, Yeungnam University College of Medicine, Daegu, South Korea.

Background: Tuberculosis is a common disease; however, the prevalence of calvarial tuberculosis is very rare. Most cases of calvarial tuberculosis occur in young patients. We report a rare case of calvarial tuberculosis in an elderly patient.

Case Description: An 89-year-old woman presented with a forehead skin defect. Radiologic imaging showed bony erosion 20 × 10 mm in size with adjacent dural enhancement in the left frontal bone. The patient underwent surgical treatment. Pathology revealed chronic granulomatous inflammation with caseous necrosis, consistent with tuberculosis. Antituberculous medications were prescribed for 6 months.

Conclusions: A careful assessment should be performed to obtain an appropriate diagnosis in cases of osteolytic lesions of the skull.
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http://dx.doi.org/10.1016/j.wneu.2020.05.076DOI Listing
August 2020

Genetic and Epigenetic Etiology Underlying Autism Spectrum Disorder.

J Clin Med 2020 Mar 31;9(4). Epub 2020 Mar 31.

Department of Stem Cell and Regenerative Biotechnology, KU Institute of Technology, Konkuk University, Seoul 05029, Korea.

Autism spectrum disorder (ASD) is a pervasive neurodevelopmental disorder characterized by difficulties in social interaction, language development delays, repeated body movements, and markedly deteriorated activities and interests. Environmental factors, such as viral infection, parental age, and zinc deficiency, can be plausible contributors to ASD susceptibility. As ASD is highly heritable, genetic risk factors involved in neurodevelopment, neural communication, and social interaction provide important clues in explaining the etiology of ASD. Accumulated evidence also shows an important role of epigenetic factors, such as DNA methylation, histone modification, and noncoding RNA, in ASD etiology. In this review, we compiled the research published to date and described the genetic and epigenetic epidemiology together with environmental risk factors underlying the etiology of the different phenotypes of ASD.
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http://dx.doi.org/10.3390/jcm9040966DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7230567PMC
March 2020

Comparative analysis of the mitochondrial morphology, energy metabolism, and gene expression signatures in three types of blastocyst-derived stem cells.

Redox Biol 2020 02 20;30:101437. Epub 2020 Jan 20.

Department of Stem Cell and Regenerative Biotechnology, Konkuk Institute of Technology, Konkuk University, Seoul, Republic of Korea. Electronic address:

Pre-implantation mouse blastocyst-derived stem cells, namely embryonic stem cells (ESCs), trophoblast stem cells (TSCs), and extraembryonic endoderm (XEN) cells, have their own characteristics and lineage specificity. So far, several studies have attempted to identify these three stem cell types based on genetic markers, morphologies, and factors involved in maintaining cell self-renewal. In this study, we focused on characterizing the three stem cell types derived from mouse blastocysts by observing cellular organelles, especially the mitochondria, and analyzing how mitochondrial dynamics relates to the energy metabolism in each cell type. Our study revealed that XEN cells have distinct mitochondrial morphology and energy metabolism compared with that in ESCs and TSCs. In addition, by analyzing the energy metabolism (oxygen consumption and extracellular acidification rates), we demonstrated that differences in the mitochondria affect the cellular metabolism in the stem cells. RNA sequencing analysis showed that although ESCs are developmentally closer to XEN cells in origin, their gene expression pattern is relatively closer to that of TSCs. Notably, mitochondria-, mitochondrial metabolism-, transport/secretory action-associated genes were differentially expressed in XEN cells compared with that in ESCs and TSCs, and this feature corresponds with the morphology of the cells.
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http://dx.doi.org/10.1016/j.redox.2020.101437DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6992993PMC
February 2020

A systematic genetic screen for genes involved in sensing inorganic phosphate availability in Saccharomyces cerevisiae.

PLoS One 2017 17;12(5):e0176085. Epub 2017 May 17.

Faculty of Arts and Sciences Center for Systems Biology, Harvard University, Cambridge, Massachusetts, United States of America.

Saccharomyces cerevisiae responds to changes in extracellular inorganic phosphate (Pi) availability by regulating the activity of the phosphate-responsive (PHO) signaling pathway, enabling cells to maintain intracellular levels of the essential nutrient Pi. Pi-limitation induces upregulation of inositol heptakisphosphate (IP7) synthesized by the inositol hexakisphosphate kinase Vip1, triggering inhibition of the Pho80/Pho85 cyclin-cyclin dependent kinase (CDK) complex by the CDK inhibitor Pho81, which upregulates the PHO regulon through the CDK target and transcription factor Pho4. To identify genes that are involved in signaling upstream of the Pho80/Pho85/Pho81 complex and how they interact with each other to regulate the PHO pathway, we performed genome-wide screens with the synthetic genetic array method. We identified more than 300 mutants with defects in signaling upstream of the Pho80/Pho85/Pho81 complex, including AAH1, which encodes an adenine deaminase that negatively regulates the PHO pathway in a Vip1-dependent manner. Furthermore, we showed that even in the absence of VIP1, the PHO pathway can be activated under prolonged periods of Pi starvation, suggesting complexity in the mechanisms by which the PHO pathway is regulated.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0176085PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5435139PMC
September 2017

Synthetic recording and in situ readout of lineage information in single cells.

Nature 2017 01 21;541(7635):107-111. Epub 2016 Nov 21.

Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA.

Reconstructing the lineage relationships and dynamic event histories of individual cells within their native spatial context is a long-standing challenge in biology. Many biological processes of interest occur in optically opaque or physically inaccessible contexts, necessitating approaches other than direct imaging. Here we describe a synthetic system that enables cells to record lineage information and event histories in the genome in a format that can be subsequently read out of single cells in situ. This system, termed memory by engineered mutagenesis with optical in situ readout (MEMOIR), is based on a set of barcoded recording elements termed scratchpads. The state of a given scratchpad can be irreversibly altered by CRISPR/Cas9-based targeted mutagenesis, and later read out in single cells through multiplexed single-molecule RNA fluorescence hybridization (smFISH). Using MEMOIR as a proof of principle, we engineered mouse embryonic stem cells to contain multiple scratchpads and other recording components. In these cells, scratchpads were altered in a progressive and stochastic fashion as the cells proliferated. Analysis of the final states of scratchpads in single cells in situ enabled reconstruction of lineage information from cell colonies. Combining analysis of endogenous gene expression with lineage reconstruction in the same cells further allowed inference of the dynamic rates at which embryonic stem cells switch between two gene expression states. Finally, using simulations, we show how parallel MEMOIR systems operating in the same cell could enable recording and readout of dynamic cellular event histories. MEMOIR thus provides a versatile platform for information recording and in situ, single-cell readout across diverse biological systems.
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http://dx.doi.org/10.1038/nature20777DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6487260PMC
January 2017

Evaluation of Data Entry Errors and Data Changes to an Electronic Data Capture Clinical Trial Database.

Drug Inf J 2011 Jul;45(4):421-430

President, Target Health Inc, New York.

Monitoring of clinical trials includes several disciplines, stakeholders, and skill sets. The aim of the present study was to identify database changes and data entry errors to an electronic data capture (EDC) clinical trial database, and to access the impact of the changes. To accomblish the aim, Target e*CRF was used as the EDC tool for a multinational, dose-finding, multicenter, double-blind, randomized, parallel, placebo-controlled trial to investigate efficacy and safety of a new treatment in men with lower urinary tract symptoms associated with benign prostatic hyperplasia. The main errors observed were simple transcription errors from the paper source documents to the EDC database. This observation was to be expected, since every transaction has an inherant error rate. What and how to monitor must be assessed within the risk-based monitoring section of the comprehensive data monitoring plan. With the advent of direct data entry, and the elimination of the requirement to transcribe from a paper source record to an EDC system, error rates should go down dramatically. In addition, protocol violations and data outside the normal range can be identified at the time of data entry and not days, weeks, and months after the fact.
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http://dx.doi.org/10.1177/009286151104500404DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3777611PMC
July 2011

Analysis of microsatellite instability, protein expression and methylation status of hMLH1 and hMSH2 genes in gastric carcinomas.

Hepatogastroenterology 2009 May-Jun;56(91-92):899-904

Department of Pathology, Daegu Fatima Hospital, Daegu, Korea.

Background/aims: Microsatellite instability (MSI) is a manifestation of a defective DNA mismatch repair system. It is caused by germline mutations of mismatch repair genes or CpG islands hypermethylation. The majority of cancers of hereditary nonpolyposis colorectal cancer (HNPCC) syndrome have MSI+ phenotype. The colorectal cancers show distinctive clinicopathological characteristics and prognoses according to the MSI status. However, there is a wide variety of results between MSI and clinicopathological parameters in gastric carcinomas.

Methodology: Five hundred and twenty-one surgically resected gastric carcinomas were studied and the correlation with clinicopathological parameters, MSI status by using five microsatellite markers, expression of hMLH1 and hMSH2 protein by immunohistochemical stain, and methylation of hMLH1 and hMSH2 by methylation-specific polymerase chain reaction was analyzed.

Results: There were 50 (9.6%) high-frequency MSI (MSI-H) cases. The MSI-H gastric carcinomas were associated with older age, expanding type by Ming's classification, lymphatic invasion, tumor multiplicity, losses of hMLH1 and hMSH2 protein expressions. The methylation frequency of hMLH1 was 75.5% in MSI-H gastric carcinomas.

Conclusions: Our results suggest that epigenetic inactivation of hMLH1 might play a role in the carcinogenesis of MSI-H gastric carcinomas. The immunohistochemical stain for hMLH1 protein expression could be used in routine diagnostic methods for predicting MSI status.
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September 2009

Bipolar resistance switching characteristics in a thin Ti-Ni-O compound film.

Nanotechnology 2009 Apr 3;20(17):175704. Epub 2009 Apr 3.

Department of Semiconductor Science, Dongguk University, Seoul, Korea.

Resistance switching phenomena in an amorphous Ni-Ti-O film were investigated. Very clear bipolar resistive switching characteristics were observed with good reproducibility. Stable retention and on/off pulse switching operation was demonstrated. An analysis of x-ray photoelectron spectroscopy of the Ni-Ti-O film provided a clue that the observed unusual bipolar resistance switching in the film is due to a microscopic change in the Ni-O and Ti-O binding states at the Ni-Ti-O film/electrode interface.
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http://dx.doi.org/10.1088/0957-4484/20/17/175704DOI Listing
April 2009