Publications by authors named "Yoon Ho Hwang"

Although the relationships between basic clinical parameters and white matter hyperintensity (WMH) have been studied, the associations between vascular factors and WMH volume in general populations remain unclear. We investigated the associations between clinical parameters including comprehensive vascular factors and WMH in two large general populations. This retrospective, cross-sectional study involved two populations: individuals who underwent general health examinations at the Asan Medical Center (AMC) and participants from a regional cohort, the Korean Genome and Epidemiology Study (KoGES).

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Background/objectives: The acute stress response affects brain metabolites closely linked to the tricarboxylic acid (TCA) cycle. This response involves time-dependent changes in hormones and neurotransmitters, which contribute to resilience and the ability to adapt to acute stress while maintaining homeostasis. This physiological mechanism of metabolic dynamics, combined with time-series analysis, has prompted the development of new methods to observe the relationship between TCA cycle-related brain metabolites.

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Despite the numerous advantages demonstrated by microfluidic mixing for RNA-loaded lipid nanoparticle (RNA-LNP) production over bulk methods, such as precise size control, homogeneous distributions, higher encapsulation efficiencies, and improved reproducibility, their translation from research to commercial manufacturing remains elusive. A persistent challenge hindering the adoption of microfluidics for LNP production is the fouling of device surfaces during prolonged operation, which significantly diminishes performance and reliability. The complexity of LNP constituents, including lipids, cholesterol, RNA, and solvent mixtures, makes it difficult to find a single coating that can prevent fouling.

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Article Synopsis
  • Microfluidic technology for creating uniform emulsion droplets has limitations in complexity, scalability, and operational stability, especially with high-viscosity fluids.
  • The study introduces a 3D-printed step-emulsification device (3D-PSD) that overcomes these issues, allowing for the production of high-viscosity emulsion droplets efficiently and consistently.
  • The device features 24 triangular nozzles and a specially designed flow system, enabling a production rate of up to 50 mL/h, and can produce both water-in-oil and oil-in-water emulsions, demonstrated by the continuous creation of biodegradable microparticles as well.
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The barrier function of the skin in effectively protecting the underlying tissue from the surrounding environment makes it challenging to achieve the efficient transdermal delivery of actives. Herein, we report on alcohol-solvent-encapsulated microcapsules to achieve enhanced skin efficacy. We show that using palm oil as the shell material allows for the microencapsulation of a broad range of alcohol solvents, including ethanol and dipropylene glycol (DPG), as well as on-demand release.

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Background And Aims: There is a demand for longitudinal studies that use both objective and subjective measures of physical activity to investigate the association of physical activity with the change in carotid intima-media thickness (CIMT). In order to investigate such association, we conducted an 8-year follow-up study that used both objective and subjective measures of physical activity.

Methods: This cohort study used subsamples of the ongoing Korean Genome and Epidemiology Study (KoGES).

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In this work, we utilize skin penetration enhancers (SPEs) such as ceramide and fatty acids in lipid nanovesicles to promote the transdermal delivery of active ingredients. These SPE-incorporated lipid nanovesicles (SPE-LNV) interact with the constituents of skin's outermost stratum corneum (SC) layer, enabling even niacinamide and adenosine with high water solubility to effectively permeate through, leading to enhanced skin efficacy. We demonstrate by both and skin permeation studies that the SPE-LNV formulation containing both ceramide and fatty acids (LNV-CF) exhibits deeper penetration depth and faster permeation rate compared to conventional lipid nanovesicles (LNV) without SPE as well as LNV-C with only ceramide.

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The acute stress response is a natural and fundamental reaction that balances the physiological conditions of the brain. To maintain homeostasis in the brain, the response is based on changes over time in hormones and neurotransmitters, which are related to resilience and can adapt successfully to acute stress. This increases the need for dynamic analysis over time, and new approaches to examine the relationship between metabolites have emerged.

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Emulsions in which water droplets are dispersed in fluorocarbon oil phase (W/F emulsions) serve as effective means to encapsulate bioactives and precisely execute reactions in confined space due to the gas permeability, chemical inertness, and biocompatibility offered by the continuous phase. While molecular surfactants consisting of perfluorinated polyether (PFPE) and polyethylene glycol (PEG) have been used to stabilize these emulsions, these surfactants cannot effectively prevent coalescence and cross-contamination between the neighboring droplets. Herein, we present Janus nanoparticles (F-SiO-PEG) as biocompatible colloidal surfactants to achieve excellent stability in W/F emulsions.

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We present a microfluidic approach that utilizes temperature-responsive and biocompatible palm oil as the shell material in microcapsules to simultaneously achieve hermetic sealing as well as on-demand temperature-triggered release of the encapsulated actives. Unlike common paraffin waxes (e.g.

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A new strategy that utilizes temperature-responsive wax-based Janus particles as microsurfactants to simultaneously achieve enhanced emulsion stability, as well as, on-demand coalescence of emulsion droplets is presented. The dumbbell structure with different surface wetting properties on each side of the Janus particle enables the particles to strongly adsorb at the liquid-liquid interface, leading to excellent stability against coalescence for both water-in-oil (W/O) and oil-in-water (O/W) emulsions. Moreover, these Janus microparticles are composed of a hydrophilic acrylate resin and a hydrophobic wax compartment which transitions from a frozen to an oil-soluble molten state above the melting point.

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The relationship between calcium ion (Ca) concentration and temperature variation during the oxidative phosphorylation (OXPHOS) process has become an essential focus for exploration of signaling pathways and neurodegenerative disease. However, there have been limited reports of fluorescent probes for simultaneous Ca detection and temperature sensing. Herein, a new water-soluble fluorescent probe that combines a thermoresponsive polymer, curcumin and Fluo-4 AM for intracelllar temperature and Ca sensing is described.

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Study Objectives: To assess, using fractional anisotropy (FA) analysis, alterations of brain network connectivity in adults with obstructive sleep apnea (OSA). Abnormal networks could mediate clinical functional deficits and reflect brain tissue injury.

Methods: Structural brain networks were constructed using diffusion tensor imaging (DTI) from 165 healthy (age 57.

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A droplet-based microfluidic synthesis approach for preparation of ficin capped gold nano clusters (AuNCs) was developed. Well dispersed AuNCs could be procured within 8 min. Upon excitation wavelength at 340 nm, the resultant AuNCs exhibited a strong blue fluorescence with the maximum emission at 450 nm.

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Many efforts have been made on stimuli-responsive switchable catalysis to trigger catalytic activity over various chemical reactions. However, the reported light-, pH- or chemically responsive organocatalysts are mostly incomplete in the aspects of shielding efficiency and long-term performance. Here, we advance the flow-assisted switchable catalysis of metal ions in a microenvelope system that allows  the on-off catalysis mode on demand for long-lasting catalytic activity.

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Simultaneous capture of carbon dioxide (CO) and its utilization with subsequent work-up would significantly enhance the competitiveness of CO-based sustainable chemistry over petroleum-based chemistry. Here we report an interfacial catalytic reaction platform for an integrated autonomous process of simultaneously capturing/fixing CO in gas-liquid laminar flow with subsequently providing a work-up step. The continuous-flow microreactor has built-in silicon nanowires (SiNWs) with immobilized ionic liquid catalysts on tips of cone-shaped nanowire bundles.

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Sleep restriction (SR) is defined as the condition of not having enough sleep, and it can cause brain injury. In this study, we examined the impact of SR on the structural brain network. We obtained diffusion MRI (dMRI) data for the SR group of fourteen participants who got less than or equal to 5.

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Intracellular temperature has a fundamental effect on cellular events. Herein, a novel fluorescent polymer ratiometric nanothermometer has been developed based on transferrin protein-stabilized gold nanoclusters as the targeting and fluorescent ratiometric unit and the thermosensitve polymer as the temperature sensing unit. The resultant nanothermometer could feature a high and spontaneous uptake into the HeLa cells and the ratiometric temperature sensing over the physiological temperature range.

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Background: Treatment for patent ductus arteriosus (PDA) in premature infants can consist of medical or surgical approaches. The appropriate therapeutic regimen remains contentious. This study evaluated the role of surgery in improving the survival of premature neonates weighing less than 1,500 g with PDA.

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Background: Platinum and 5-fluorouracil (5-FU)-based regimens have been used the most frequently in palliative chemotherapy for gastric cancer. The present study evaluated the prognostic significance of Bax, excision repair cross-complementation group 1 (ERCC1), and thymidylate synthase (TS) in advanced gastric cancer patients treated with 5-FU, leucovorin, and oxaliplatin (FOLFOX) palliative chemotherapy.

Methods: Seventy-two patients with metastatic or recurrent gastric cancer were treated with FOLFOX regimen.

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We evaluated the prognostic significance of excision repair cross-complementation group 1 protein (ERCC1) and thymidylate synthase (TS) in patients with nasopharyngeal cancer (NPC) treated with concurrent chemoradiotherapy (CCRT). Pre-treatment tumor biopsy specimens from 41 patients with locally advanced NPC (stage I: 1, II: 10, III: 9, IV: 21 patients) were analyzed for ERCC1 and TS expression by immunohistochemistry. All patients were treated with one cycle of induction chemotherapy (5-fluorouracil 1000 mg/m(2)/day and cisplatin 20mg/m(2)/day, days 1-4) followed by CCRT starting on day 22.

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A 69-year-old male presented with obstructive hypertrophic cardiomyopathy, mitral valve regurgitation, and myxomatous mitral valve prolapse. A spontaneous chordal rupture and acute severe mitral regurgitation resulted in abrupt clinical deterioration despite complete relief of severe left ventricular outflow tract obstruction and systolic anterior motion of the anterior mitral leaflet. The patient underwent extensive cardiac surgery due to intractable heart failure.

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Background: Platinum-based concurrent chemoradiotherapy (CCRT) is a standard treatment for locally advanced unresectable non-small cell lung cancer (NSCLC). The determination of parameters that may predict the result of the treatment has strong clinical implications.

Patients And Methods: Pretreatment tumor biopsy specimens from 39 patients with locally advanced NSCLC (stage IIIA: 5, stage IIIB: 34) were analyzed for p53, Bcl-2, Bax and ERCC1 expression by immunohistochemistry.

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Synopsis of recent research by authors named "Yoon Ho Hwang"

  • - Yoon Ho Hwang's recent research focuses on the intersection of innovative delivery systems and the understanding of biological processes, with applications in microfluidics, transdermal drug delivery, and neuroscience.
  • - His studies include a 3D-printed device for scalable emulsion production, microencapsulation techniques enhancing transdermal efficacy, and the investigation of the effects of physical activity on carotid intima-media thickness over time.
  • - The findings demonstrate advancements in biocompatible materials and devices for improved health outcomes, highlighting the potential for new methodologies in drug delivery and the impact of physical activity on vascular health.