Publications by authors named "Seung Kwon Yang"

In this study, statistical analysis and forecasting were performed using coastal litter data of Korea. The analysis indicated that rope and vinyl accounted for the highest proportion of coastal litter items. The statistical analysis of the national coastal litter trends revealed that the greatest concentration of litter was observed during summer months (June-August).

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Vagal sensory neurons contribute to the symptoms and pathogenesis of inflammatory pulmonary diseases through processes that involve changes to their morphological and functional characteristics. The alarmin high mobility group box-1 (HMGB1) is an early mediator of pulmonary inflammation and can have actions on neurons in a range of inflammatory settings. We hypothesized that HMGB1 can regulate the growth and function of vagal sensory neurons and we set out to investigate this and the mechanisms involved.

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Despite progress, our understanding of psychiatric and neurological illnesses remains poor, at least in part due to the inability to access neurons directly from patients. Currently, there are models available but significant work remains, including the search for a less invasive, inexpensive and rapid method to obtain neuronal-like cells with the capacity to deliver reproducible results. Here, we present a new protocol to transdifferentiate human circulating monocytes into neuronal-like cells in 20 days and without the need for viral insertion or reprograming.

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Coronary intervention following ST-segment elevation myocardial infarction (STEMI) is the treatment of choice for reducing cardiomyocyte death but paradoxically leads to reperfusion injury. Pharmacological post-conditioning is an attractive approach to minimize Ischemia-Reperfusion Injury (IRI), but candidate drugs identified in IRI animal models have performed poorly in human clinical trials, highlighting the need for a cell-based model of IRI. In this work, we show that when we imposed sequential hypoxia and reoxygenation episodes [mimicking the ischemia (I) and reperfusion (R) events] to immature human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs), they display significant hypoxia resistance and minimal cell death (∼5%).

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The airway sensory nervous system is composed of two anatomically distinct processing pathways that allow for the production of respiratory reflexes and voluntary evoked respiratory behaviours in response to sensing an airway irritation. Disordered sensory processing is a hallmark feature of many pulmonary disorders and results in the development of cough hypersensitivity syndrome, characterised by chronic cough and a persistent urge-to-cough in affected individuals. However, the mechanism underpinning how the airway sensory circuits become disordered, especially at the level of the central nervous system, is not well understood.

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The airways and lungs are densely innervated by sensory nerves, which subserve multiple roles in both the normal physiological control of respiratory functions and in pulmonary defense. These sensory nerves are therefore not homogeneous in nature, but rather have physiological, molecular and anatomical phenotypes that reflect their purpose. All sensory neuron subtypes provide input to the central nervous system and drive reflex changes in respiratory and airway functions.

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Article Synopsis
  • * Researchers utilized advanced tracing techniques and genetic methods to examine how sensory information from the trachea and lungs is processed in the brain.
  • * Results indicate that sensory neurons from different parts of the respiratory system connect to distinct brain regions, which may explain the unique sensations experienced from the upper and lower airways.
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The prospective isolation of defined contractile human pluripotent stem cell (hPSC)-derived cardiomyocytes is advantageous for regenerative medicine and drug screening applications. Currently, enrichment of cardiomyocyte populations from such cultures can be achieved by combinations of cell surface markers or the labor-intensive genetic modification of cardiac developmental genes, such as NKX2.5 or MYH6, with fluorescent reporters.

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There is an overwhelming body of evidence to support the existence of higher brain circuitries involved in the sensory detection of airways irritation and the motor control of coughing. The concept that cough is purely a reflex response to airways irritation is now superseded by the recognition that perception of an urge-to-cough and altered behavioral modification of coughing are key elements of cough disorders associated with airways disease. Understanding the pathways by which airway sensory nerves ascend into the brain and the patterns of neural activation associated with airways irritation will undoubtedly provide new insights into disordered coughing.

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Background: Ghrelin and obestatin are two gut-derived peptides originating from the same ghrelin/obestatin prepropeptide gene (GHRL). While ghrelin stimulates growth hormone (GH) secretion and food intake and inhibits γ-aminobutyric-acid synaptic transmission onto GHRH (Growth Hormone Releasing Hormone) neurons, obestatin blocks these effects. In Humans, GHRL gene polymorphisms have been associated with pathologies linked to an unbalanced energy homeostasis.

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Article Synopsis
  • Growth hormone (GH) is secreted by somatotrophs in the anterior pituitary gland, influenced by hypothalamic GHRH and ghrelin, while inhibited by somatostatin (SRIF).
  • These factors interact with G-protein-coupled receptors, affecting ion channels and intracellular signaling that ultimately alters calcium ion concentration ([Ca(2+)](i)) and hormone release.
  • The review emphasizes the significance of ion channels and calcium dynamics in somatotrophs for regulating GH secretion, addressing issues like receptor distribution and membrane potential changes.
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Ghrelin, a natural ligand of the growth hormone secretagogue receptor (GHS-R), is synthesized in the stomach but may also be expressed in lesser quantity in the hypothalamus where the GHS-R is located on growth hormone-releasing hormone (GHRH) neurons. Obestatin, a peptide derived from the same precursor as ghrelin, is able to antagonize the ghrelin-induced increase of growth hormone (GH) secretion in vivo but not from pituitary explants in vitro. Thus, the blockade of ghrelin-induced GH release by obestatin could be mediated at the hypothalamic level by the neuronal network that controls pituitary GH secretion.

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Ghrelin and obestatin are two peptides isolated from the gastrointestinal tract and encoded by the same preproghrelin gene. They convey to the central nervous system informations concerning the nutritional status and/or the energy stores. Ghrelin, mostly acting through the GH secretagogue receptor GHS-R, is a potent GH secretagogue, an orexigenic peptide and a long-term regulator of energy homeostasis.

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GHRH depolarizes the membrane of somatotropes, leading to an increase in intracellular free Ca2+ concentration and GH secretion. Na+ channels mediate the rapid depolarization during the initial phase of the action potential, and this regulates Ca2+ influx and GH secretion. GHRH increases a tetrodotoxin-sensitive somatotrope Na+ current that is mediated by cAMP.

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1. Growth hormone (GH) secretion from pituitary somatotropes is mainly regulated by two hypothalamic hormones, GH-releasing hormone (GHRH) and somatotrophin releasing inhibitory factor (SRIF). 2.

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The secretion of growth hormone (GH) is inhibited by hypothalamic somatostatin (SRIF) in somatotropes through five subtypes of the somatostatin receptor (SSTR1-SSTR5). We aimed to characterize the subtype(s) of SSTRs involved in the Ca2+ current reduction in GH3 somatotrope cells using specific SSTR subtype agonists. We used nystatin-perforated patch clamp to record voltage-gated Ca2+ currents, using a holding potential of -80 mV in the presence of K+ and Na+ channel blockers.

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The secretion of GH by somatotropes is inhibited by somatostatin (SRIF) through five specific membrane receptors (SSTRs). SRIF increases both transient outward (IA) and delayed rectifying (IK) K+ currents. We aim to clarify the subtype(s) of SSTRs involved in K+ current enhancement in GH3 somatotrope cells using specific SSTR subtype agonists.

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