Publications by authors named "Hyuk Nam Kwon"

Initially considered distinct systems with independent physiological functions, recent evidence highlights the crucial role of active crosstalk between the nervous and immune systems in regulating critical physiological and neurological processes and immunological homeostasis. The identification of a direct body-brain circuitry allowing the monitoring of peripheral inflammatory responses, a unique skull bone marrow source of immune cells to the central nervous system (CNS), and the physical interface of the blood-brain barrier with the meningeal system suggest direct intersystem interactions, which can be further modulated by the local tissue environment, allowing non-neurological factors to influence neurological outcomes and vice versa. While there is a recognized age-dependent decline in both neurological and immune system function, in part due to the natural accumulation of cellular defects and the development of chronic systemic inflammation, it is unclear if the pre-existing bidirectional feedback mechanisms between the neurological and peripheral immune system plays a role in shaping the system decline, beyond commonly investigated pathological conditions.

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Idiopathic pulmonary fibrosis is a chronic and incurable lung disease characterized by progressive destruction and scarring of lung tissue. A hallmark of Idiopathic pulmonary fibrosis is the accumulation of extracellular matrix produced by differentiated myofibroblasts. Recent studies have highlighted the role of reactive oxygen species and mitochondrial dysfunction in myofibroblast differentiation and disease progression.

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PD-L1 immunohistochemistry (IHC) assays are used as a companion diagnostic for immunotherapy with immune checkpoint inhibitors (ICIs). However, despite the association between PD-L1 expression and clinical benefit from ICIs, the PD-L1 IHC assay is not sufficiently accurate in predicting response to ICIs; some patients with high PD-L1 expression do not respond to ICIs. Recently, researchers provided insights into why some patients with high PD-L1 expression fail to respond to ICIs.

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Purpose: Developmentally regulated GTP-binding protein 2 (DRG2) regulates microtubule dynamics and G2/M arrest during docetaxel treatment. Poly ADP-ribose polymerase (PARP) acts as an important repair system for DNA damage caused by docetaxel treatment. This study investigated whether DRG2 expression affects response to PARP inhibitors (olaparib) using prostate cancer cell lines PC3, DU145, LNCaP-FGC, and LNCaP-LN3.

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Eukaryotic translation initiation factor 2α (eIF2α) phosphorylation, which regulates all 3 unfolded protein response pathways, helps maintain cellular homeostasis and overcome endoplasmic reticulum (ER) stress through transcriptional and translational reprogramming. However, transcriptional regulation of mitochondrial homeostasis by eIF2α phosphorylation during ER stress is not fully understood. Here, we report that the eIF2α phosphorylation-activating transcription factor 4 (ATF4) axis is required for the expression of multiple transcription factors, including nuclear factor erythroid 2-related factor 2 and its target genes responsible for mitochondrial homeostasis during ER stress.

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A type of programmed cell death called ferroptosis is defined by increased iron-dependent lipid peroxidation. Mitochondria play a central role in iron metabolism. Mitochondrial defects include decreased cristae density, membrane rupture, and decreased mitochondrial membrane density, which occur as a result of ferroptosis.

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Background: The maternal microbiota modulates fetal development, but the mechanisms of these earliest host-microbe interactions are unclear. To investigate the developmental impacts of maternal microbial metabolites, we compared full-term fetuses from germ-free and specific pathogen-free mouse dams by gene expression profiling and non-targeted metabolomics.

Results: In the fetal intestine, critical genes mediating host-microbe interactions, innate immunity, and epithelial barrier were differentially expressed.

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This study primarily aimed to evaluate whether peritoneal equilibration test (PET) results can be predicted through the metabolomic analysis of overnight peritoneal dialysis (PD) effluents. From a total of 125 patients, overnight PD effluents on the day of the first PET after PD initiation were analyzed. A modified 4.

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Nephron endowment is defined by fetal kidney growth and crucially dictates renal health in adults. Defects in the molecular regulation of nephron progenitors contribute to only a fraction of reduced nephron mass cases, suggesting alternative causative mechanisms. The importance of MAPK/ERK activation in nephron progenitor maintenance has been previously demonstrated, and here, we characterized the metabolic consequences of MAPK/ERK deficiency.

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Background: MAPK/ERK signaling is a well-known mediator of extracellular stimuli controlling intracellular responses to growth factors and mechanical cues. The critical requirement of MAPK/ERK signaling for embryonic stem cell maintenance is demonstrated, but specific functions in progenitor regulation during embryonic development, and in particular kidney development remain largely unexplored. We previously demonstrated MAPK/ERK signaling as a key regulator of kidney growth through branching morphogenesis and normal nephrogenesis where it also regulates progenitor expansion.

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The early detection of gastric cancer (GC) could decrease its incidence and mortality. However, there are currently no accurate noninvasive markers for GC screening. Therefore, we developed a noninvasive diagnostic approach, employing urine nuclear magnetic resonance (NMR) metabolomics, to discover putative metabolic markers associated with GC.

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Isocitrate dehydrogenase (IDH) mutations are found in low-grade gliomas, and the product of the IDH mutant (MT), 2-hydroxyglutarate (2-HG), is the first known oncometabolite. However, the roles of the IDH wild type (WT) in high-grade glioblastoma, which rarely has the IDH mutation, are still unknown. To investigate possible pathways related to IDH WT in gliomas, we carried out bioinformatics analysis, and found that IDH1 has several putative calmodulin (CaM) binding sites.

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Sleep fragmentation (SF) commonly occurs in several pathologic conditions and is especially associated with impairments of hippocampus-dependent neurocognitive functions. Although the effects of SF on hippocampus in terms of protein or gene levels were examined in several studies, the impact of SF at the metabolite level has not been investigated. Thus, in this study, the differentially expressed large-scale metabolite profiles of hippocampus in a rat model of SF were investigated using untargeted metabolomics approaches.

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Congenital anomalies of the kidney and urinary tract (CAKUT) are common birth defects derived from abnormalities in renal differentiation during embryogenesis. CAKUT is the major cause of end-stage renal disease and chronic kidney diseases in children, but its genetic causes remain largely unresolved. Here we discuss advances in the understanding of how mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) activity contributes to the regulation of ureteric bud branching morphogenesis, which dictates the final size, shape, and nephron number of the kidney.

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Although colorectal cancer (CRC) is considered one of the most preventable cancers, no non-invasive, accurate diagnostic tool to screen CRC exists. We explored the potential of urine nuclear magnetic resonance (NMR) metabolomics as a diagnostic tool for early detection of CRC, focusing on advanced adenoma and stage 0 CRC. Urine metabolomics profiles from patients with colorectal neoplasia (CRN; 36 advanced adenomas and 56 CRCs at various stages, n = 92) and healthy controls (normal, n = 156) were analyzed by NMR spectroscopy.

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The in vivo niche and basic cellular properties of nephron progenitors are poorly described. Here we studied the cellular organization and function of the MAPK/ERK pathway in nephron progenitors. Live-imaging of ERK activity by a Förster resonance energy transfer biosensor revealed a dynamic activation pattern in progenitors, whereas differentiating precursors exhibited sustained activity.

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Introduction: Herbal medicines have been used for a long time all around the world. Since the quality of herbal preparations depends on the source of herbal materials, there has been a strong need to develop methods to correctly identify the origin of materials.

Objective: To develop a smartphone metabolomics platform as a simpler and low-cost alternative for the identification of herbal material source.

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Metabolic surgery has been shown to provide better glycemic control for type 2 diabetes than conventional therapies. Still, the outcomes of the surgery are variable, and prognostic markers reflecting the metabolic changes by the surgery are yet to be established. NMR-based plasma metabolomics followed by multivariate regression was used to test the correlation between the metabolomic profile at 7-days after surgery and glycated hemoglobin (HbA1c) levels at 3-months (and up to 12 months with less patients), and to identify the relevant markers.

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The suppressor domain of inositol 1,4,5 trisphosphate receptor (IP3R) has critical roles in regulating the calcium channel by interacting with many binding partners. The residue 49-53 (PPKKF) of the suppressor domain was suggested to be a canonical Homer EVH1 domain binding site and is also the first a part of calmodulin (CaM) binding site. As CaM-binding of the suppressor domain has been shown to involve large-scale conformational changes, we studied the binding characteristics of the Homer EVH1-suppressor domain with NMR spectroscopy and biochemical pull-down assays for mutants.

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Minimally invasive plate osteosynthesis (MIPO) has been used for humeral shaft fractures, but concerns exist about soft tissue injuries. The purpose of this study was to report the surgical technique and clinical outcomes of MIPO using a helical plate for metadiaphyseal complex humeral shaft fractures. Twelve patients with acute displacement involving proximal and middle third humeral shaft fractures (AO type C) were treated using the MIPO technique with a helical plate.

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Alterations in metabolic pathways are gaining attention as important environmental factors affecting life span, but the determination of specific metabolic pathways and enzymes involved in life span remains largely unexplored. By applying an NMR-based metabolomics approach to a calorie-restricted yeast (Saccharomyces cerevisiae) model, we found that alanine level is inversely correlated with yeast chronological life span. The involvement of the alanine-metabolizing pathway in the life span was tested using a deletion mutant of ALT1, the gene for a key alanine-metabolizing enzyme.

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Background: Simvastatin, which is used to control elevated cholesterol levels, is one of the most widely prescribed drugs. However, a daily excessive dose can induce drug-toxicity, especially in muscle and liver. Current markers for toxicity reflect mostly the late stages of tissue damage; thus, more efficient methods of toxicity evaluation are desired.

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Cisplatin has been one of the most widely used anticancer agents, but its nephrotoxicity remains a dose-limiting complication. Here, we evaluated the idiopathic nature and the predose prediction of cisplatin-induced nephrotoxicity using a nuclear magnetic resonance (NMR)-based pharmacometabonomic approach. Cisplatin produced serious toxic responses in some animals (toxic group), but had little effect in others (nontoxic group), as judged by hematological and histological results.

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Background & Aims: Biliary tract cancer is highly lethal at presentation, with increasing mortality worldwide. Current diagnostic measures employing multiple criteria such as imaging, cytology, and serum tumor markers are not satisfactory, and a new diagnostic tool is needed. Because bile is a cognate metabolite-rich bio-fluid in the biliary ductal system, we tested a new metabolomic approach to develop an effective diagnostic tool.

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Correct identification of the origins of herbal medical products is becoming increasingly important in tandem with the growing interest in alternative medicine. However, visual inspection of raw material is still the most widely used method, and newer scientific approaches are needed. To develop a more objective and efficient tool for discriminating herbal origins, particularly Korean and Chinese, we employed a nuclear magnetic resonance (NMR)-based metabolomics approach combined with an orthogonal projections to latent structure-discriminant analysis (OPLS-DA) multivariate analysis.

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