Publications by authors named "Sung-Jun Han"

Transcranial direct current stimulation (tDCS) is emerging as a promising non-invasive intervention for tinnitus by aiming to modulate abnormal brain activity. This study investigated the efficacy of dual-session tDCS for the relief of perception, distress, and loudness in patients with severe chronic subjective tinnitus and assessed the duration of tinnitus suppression effects compared to single-session and control groups over a 2-month follow-up. In a prospective, randomized, single-blind, placebo-controlled trial, 30 participants with severe chronic subjective tinnitus underwent bifrontal tDCS.

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Objectives/hypothesis: The pathophysiology of cholesteatoma is not precisely understood, and research on the associated microRNAs (miRNAs) is also deficient. We demonstrated the expression of miRNA in normal skin and middle ear cholesteatoma by next-generation sequencing (NGS) technology. The profiles of miRNA and relevant molecular interaction pathways were investigated.

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The optimal treatment for sudden sensorineural hearing loss (SSNHL) is unclear. Hyperbaric oxygen therapy (HBOT) has been suggested as a viable option for treatment of SSNHL as it improves vascular dysfunction. In this study, we evaluated the therapeutic effects of HBOT by retrospectively reviewing the records of 2206 patients with SSNHL.

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Positive airway pressure (PAP) is an important treatment tool for patients with moderate and severe obstructive sleep apnea (OSA), and adherence to PAP significantly affects treatment outcomes. Disease severity, adverse effects, and psychosocial factors are known to predict medication adherence. Cephalometric parameters have been reported to positively correlate with upper airway collapse.

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Article Synopsis
  • Ear canal skin is closely linked to the bone and eardrum, and acute otitis externa (a type of ear infection) causes inflammation and swelling in the ear canal.
  • Researchers analyzed samples from 28 individuals (14 with otitis externa and 14 healthy controls) to study the differences in the ear microbiome using DNA sequencing.
  • The study found that the microbiome diversity was lower in those with otitis externa, revealing specific bacterial differences that could help inform targeted treatments for the condition.
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Genotoxicity testing is an important component of toxicity assessment. As illustrated by the European registration, evaluation, authorization, and restriction of chemicals (REACH) directive, it concerns all the chemicals used in industry. The commonly used in vivo mammalian tests appear to be ill adapted to tackle the large compound sets involved, due to throughput, cost, and ethical issues.

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A critical step in providing better phosphor solution for white light emitting diode (LED) is to utilize inexpensive silicate phosphors with strong thermal stability. Here, we demonstrate yellow silicate phosphor-embedded glass thick films with a high luminous efficacy of ∼32 lm/W at 200 mA as a nonconventional remote-phosphor approach. The simple screen-printing process of a paste consisting of (Ba,Sr,Ca)₂SiO₄:Eu²⁺ phosphor and a low softening point glass creates a planar remote structure on a regular soda lime silicate glass with controllable film thickness and location (top vs bottom) of the phosphor layer.

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We identified a novel class of 2-((phenylsulfonyl)methyl)-thieno[3,2-d]pyrimidine compounds as potent HIV-1 replication inhibitors serendipitously during the process of evaluation of triazolothienopyrimidine (TTPM) compounds. Herein, we report synthesis and biological evaluation of 2-((phenylsulfonyl)methyl)-thieno[3,2-d]pyrimidine compounds using a cell-based full replication assay to identify thienopyrimidines 6 and 30, which could be further utilized as viable lead compounds.

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Endogenous small interfering RNAs (endo-siRNAs) are a newly emerged class of small regulatory RNAs. In Drosophila melanogaster, the production of endo-siRNAs depends on the RNase III enzyme Dicer-2 (Dcr-2). Loss of dcr-2 function reduces the resistance of adult flies to various stresses and shortens their life span.

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The activities and side effects of 5-lipoxygenase (5-LO) inhibitors can be predicted by identifying their redox mechanisms. In this study, we developed a fluorescence-based method to measure the redox potential of 5-LO inhibitors and compared it to the conventional, absorbance-based method. After the pseudo-peroxidase reaction, the amount of remaining lipid peroxide was quantified using the H2DCFDA (2',7'-dichlorodihydrofluorescein diacetate) fluorescence dye.

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A total of 140,000 compounds were screened in a targetfree cell-based high throughput assay against HIV-1 infection, and a subset of 81 promising compounds was identified. Secondary screening of these 81 compounds revealed two putative human RNaseH2 inhibitors, RHI001 and RHI002, with IC50 value of 6.8 μM and 16 μM, respectively.

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New therapeutic strategies are needed to combat the tuberculosis pandemic and the spread of multidrug-resistant (MDR) and extensively drug-resistant (XDR) forms of the disease, which remain a serious public health challenge worldwide. The most urgent clinical need is to discover potent agents capable of reducing the duration of MDR and XDR tuberculosis therapy with a success rate comparable to that of current therapies for drug-susceptible tuberculosis. The last decade has seen the discovery of new agent classes for the management of tuberculosis, several of which are currently in clinical trials.

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Classical target-based, high-throughput screening has been useful for the identification of inhibitors for known molecular mechanisms involved in the HIV life cycle. In this study, the development of a cell-based assay that uses a phenotypic drug discovery approach based on automated high-content screening is described. Using this screening approach, the antiviral activity of 26,500 small molecules from a relevant chemical scaffold library was evaluated.

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We identified a novel class of triazolothienopyrimidine (TTPM) compounds as potent HIV-1 replication inhibitors during a high-throughput screening campaign that evaluated more than 200,000 compounds using a cell-based full replication assay. Herein, we report the optimization of the antiviral activity in a cell-based assay system leading to the discovery of aryl-substituted TTPM derivatives (38, 44, and 45), which exhibited significant inhibition of HIV-1 replication with acceptable safety margins. These novel and potent TTPMs could serve as leads for further development.

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RNA interference is a eukaryotic regulatory mechanism by which small non-coding RNAs typically mediate specific silencing of their cognate genes. In Drosophila, the RNase III enzyme Dicer-2 (Dcr-2) is essential for biogenesis of endogenous small interfering RNAs (endo-siRNAs), which have been implicated in regulation of endogenous protein-coding genes. Although much is known about microRNA-based regulatory networks, the biological functions of endo-siRNAs in animals remain poorly understood.

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We identified a novel class of aryl-substituted triazine compounds as potent non-nucleoside reverse transcriptase inhibitors (NNRTIs) during a high-throughput screening campaign that evaluated more than 200000 compounds for antihuman immunodeficiency virus (HIV) activity using a cell-based full replication assay. Herein, we disclose the optimization of the antiviral activity in a cell-based assay system leading to the discovery of compound 27, which possessed excellent potency against wild-type HIV-1 (EC50 = 0.2 nM) as well as viruses bearing Y181C and K103N resistance mutations in the reverse transcriptase gene.

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Following the previous SAR of a novel dihydropyrimidinone scaffold as HIV-1 replication inhibitors a detailed study directed towards optimizing the metabolic stability of the ester functional group in the dihydropyrimidinone (DHPM) scaffold is described. Replacement of the ester moiety by thiazole ring significantly improved the metabolic stability while retaining antiviral activity against HIV-1 replication. These novel and potent DHPMs with bioisosteres could serve as advanced leads for further optimization.

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3,4-Dihydropyrimidin-2(1H)-ones (DHPMs) were selected and derivatized through a HIV-1 replication assay based on GFP reporter cells. Compounds 14, 25, 31, and 36 exhibited significant inhibition of HIV-1 replication with a good safety profile. Chiral separation of each enantiomer by fractional crystallization showed that only the S enantiomer retained anti-HIV activity.

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Tuberculosis is still a leading cause of death worldwide. The selection and spread of Mycobacterium tuberculosis multidrug-resistant (MDR-TB) and extensively drug-resistant strains (XDR-TB) is a severe public health problem. Recently, two different classes of chemical series, the benzothiazinones (BTZ) and the dinitrobenzamide (DNB) derivatives have been found to be highly active against M.

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Small non-coding RNAs regulate gene expression in a sequence-specific manner. In Drosophila, Dicer-2 (Dcr-2) functions in the biogenesis of endogenous small interfering RNAs (endo-siRNAs). We identified 21 distinct proteins that exhibited a ≥ 1.

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Hempseed, a rich source of polyunsaturated fatty acids (PUFAs) and phytosterols, has been recognized as a potential therapeutic food used for cardioprotection, preventing platelet aggregation, and improving atopic dermatitis. Although several studies have revealed the physiological benefits of hempseed on a variety of animals, the effects of dietary hempseed intake on animal development are currently unknown. In this study, we evaluated the developmental effects of the addition of hempseed meal (HSM) to the diet of Drosophila.

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Objective: An increase in the rate of hepatic glucose production is the major determinant of fasting hyperglycemia in type 2 diabetes. A better understanding of the signaling pathways and molecules that regulate hepatic glucose metabolism is therefore of great clinical importance. Recent studies suggest that an increase in vagal outflow to the liver leads to decreased hepatic glucose production and reduced blood glucose levels.

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Imaging of specific mRNA targets in cells is of great importance in understanding gene expression and cell signaling processes. Subcellular localization of mRNA is known as a universal mechanism for cells to sequester specific mRNA for high production of required proteins. Various gene expressions in Drosophila cells are studied using quantum dots (QDs) and the fluorescence in situ hybridization (FISH) method.

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The molecular pathways that promote the proliferation and maintenance of pituitary somatotrophs and other cell types of the anterior pituitary gland are not well understood at present. However, such knowledge is likely to lead to the development of novel drugs useful for the treatment of various human growth disorders. Although muscarinic cholinergic pathways have been implicated in regulating somatotroph function, the physiological relevance of this effect and the localization and nature of the receptor subtypes involved in this activity remain unclear.

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Little is known about the nature of the conformational changes that convert G-protein-coupled receptors (GPCRs), which bind diffusible ligands, from their resting into their active states. To gain structural insight into this process, various laboratories have used disulfide cross-linking strategies involving cysteine-substituted mutant GPCRs. Several recent disulfide cross-linking studies using the M(3) muscarinic acetylcholine receptor as a model system have led to novel insights into the conformational changes associated with the activation of this prototypical class I GPCR.

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