Biomedical subjects

Junwon Lee

Publications and source records attributed to Junwon Lee.

7 recordsLinked to original sources

PubMed2026

Clinical Utility of Ultra-Widefield Swept-Source OCT for Intraocular Tumors: Comparison With Ultrasonography, SD-OCT, and MRI.

PURPOSE: To evaluate the clinical performance of ultra-widefield swept-source optical coherence tomography (UWF-OCT) in the assessment of choroidal tumors and to compare it with ultrasonography (US), spectral-domain (SD)-OCT, and magnetic resonance imaging (MRI). DESIGN: Retrospective diagnostic comparison. SUBJECTS: Thirty-nine eyes from 39 patients diagnosed with choroidal tumors at a single tertiary referral center. METHODS: This retrospective diagnostic comparison evaluated patients diagnosed with choroidal tumors at a single tertiary referral center between January 2023 and August 2025. All patients underwent UWF-OCT imaging at diagnosis. Tumor measurements obtained with UWF-OCT were compared with US, SD-OCT, and MRI. Comparative analysis among imaging modalities and predictors affecting UWF-OCT applicability was performed. MAIN OUTCOME MEASURES: Tumor thickness (mm) and largest basal diameter (LBD, mm) measurements, and complete measurability rate across different tumor size categories. RESULTS: Thirty-nine eyes from 39 patients (mean age 59.2 ± 16.9 years) were analyzed, including 27 choroidal melanomas (69.2%), 5 metastatic tumors (12.8%), 4 hemangiomas (10.3%), 2 osteomas (5.1%), and 1 (2.6%) indeterminate choroidal melanocytic lesion. UWF-OCT successfully measured both tumor thickness and largest basal diameter (LBD) in 100% (31/31) of small and medium choroidal tumors, substantially outperforming SD-OCT (complete measurement achieved in 63.6% of small tumors, and 0% of medium or large tumors). UWF-OCT measurements were systematically smaller than ultrasonography (thickness: -32.3%, P < .01; LBD: -11.1%, P < .01) and MRI (thickness: -29.2%, P < .01). Mushroom-shaped tumor morphology was the strongest negative predictor of UWF-OCT quality (OR = 0.015, 95% CI 0.001-0.196, P < .01). UWF-OCT's complete measurability was limited in large tumors (12.5%, 1/8). CONCLUSIONS: UWF-OCT provides precise, noninvasive, single-scan assessment of small-to-medium choroidal tumors with detailed structural visualization. It may be particularly useful for dome-shaped tumors, while multimodal imaging with US and MRI remains optimal for complex morphologies. Overall, UWF-OCT represents a valuable tool for diagnosis and treatment planning, with potential utility for longitudinal follow-up in choroidal tumor management.

Humans↗

PubMed2006

MafB negatively regulates RANKL-mediated osteoclast differentiation.

Receptor activator of nuclear factor kappaB ligand (RANKL) induces osteoclast formation from hematopoietic cells via regulation of various transcription factors. Here, we show that MafB negatively regulates RANKL-induced osteoclast differentiation. Expression levels of MafB are significantly reduced by RANKL during osteoclastogenesis. Overexpression of MafB in bone marrow-derived monocyte/macrophage lineage cells (BMMs) inhibits the formation of TRAP(+) multinuclear osteoclasts, but phagocytic activity of BMMs is retained. Furthermore, overexpression of MafB in BMMs attenuates the gene induction of NFATc1 and osteoclast-associated receptor (OSCAR) during RANKL-mediated osteoclastogenesis. In addition, MafB proteins interfere with the DNA-binding ability of c-Fos, Mitf, and NFATc1, inhibiting their transactivation of NFATc1 and OSCAR. Furthermore, reduced expression of MafB by RNAi enhances osteoclastogenesis and increases expression of NFATc1 and OSCAR. Taken together, our results suggest that MafB can act as an important modulator of RANKL-mediated osteoclastogenesis.

Animals↗

PubMed2006

Ribavirin enhances osteoclast formation through osteoblasts via up-regulation of TRANCE/RANKL.

Hepatitis C combination therapy comprising ribavirin and interferon-alpha causes dramatic improvement with the sustained virological response; however, this treatment may result in the loss of bone mineral density. To investigate the effects of ribavirin on bone cells, we examined osteoblast differentiation as well as the formation of osteoclasts from their precursors. Ribavirin enhances osteoclast formation through osteoblasts by up-regulation of TRANCE/RANKL gene expression, whereas it has no significant effect on either osteoblast differentiation or on bone formation. Understanding ribavirin's underlying mechanism of action on bone cells will enable the improved management of bone loss in chronic hepatitis C patients.

Alkaline Phosphatase↗

PubMed2005

Id helix-loop-helix proteins negatively regulate TRANCE-mediated osteoclast differentiation.

Tumor necrosis factor (TNF)-related activation-induced cytokine (TRANCE) induces osteoclast formation from monocyte/macrophage lineage cells via various transcription factors, including the Mi transcription factor (Mitf). Here, we show that inhibitors of differentiation/DNA binding (Ids), helix-loop-helix (HLH) transcription factors, negatively regulate TRANCE-induced osteoclast differentiation. Expression levels of Id1, Id2, and Id3 genes are significantly reduced by TRANCE during osteoclastogenesis. Interestingly, overexpression of the 3 Id genes in bone marrow-derived monocyte/macrophage lineage cells (BMMs) inhibits the formation of tartrate-resistant acid phosphatase (TRAP)-positive multinuclear osteoclasts, but it does not alter the ability of BMMs to either phagocytose or differentiate into dendritic cells (DCs). Overexpression of Id2 in BMMs attenuates the gene induction of nuclear factor of activated T cells c1 (NFATc1) and osteoclast-associated receptor (OSCAR) during TRANCE-mediated osteoclastogenesis. Furthermore, Id proteins interact with Mitf, a basic HLH (bHLH) transcription factor, and inhibit its transactivation of OSCAR, which is a costimulatory receptor expressed by osteoclast precursors, by attenuating the DNA binding ability of Mitf to the E-box site of the OSCAR promoter. Taken together, our results reveal both a new facet of negative regulation, mediated by Id proteins, as well as the mechanism whereby TRANCE signaling overcomes it, allowing osteoclastogenesis to proceed.

Animals↗

PubMed2005

Osteoclast differentiation independent of the TRANCE-RANK-TRAF6 axis.

Osteoclasts are derived from myeloid lineage cells, and their differentiation is supported by various osteotropic factors, including the tumor necrosis factor (TNF) family member TNF-related activation-induced cytokine (TRANCE). Genetic deletion of TRANCE or its receptor, receptor activator of nuclear factor kappaB (RANK), results in severely osteopetrotic mice with no osteoclasts in their bones. TNF receptor-associated factor (TRAF) 6 is a key signaling adaptor for RANK, and its deficiency leads to similar osteopetrosis. Hence, the current paradigm holds that TRANCE-RANK interaction and subsequent signaling via TRAF6 are essential for the generation of functional osteoclasts. Surprisingly, we show that hematopoietic precursors from TRANCE-, RANK-, or TRAF6-null mice can become osteoclasts in vitro when they are stimulated with TNF-alpha in the presence of cofactors such as TGF-beta. We provide direct evidence against the current paradigm that the TRANCE-RANK-TRAF6 pathway is essential for osteoclast differentiation and suggest the potential existence of alternative routes for osteoclast differentiation.

Animals↗

PubMed2005

Nuclear factor of activated T cells c1 induces osteoclast-associated receptor gene expression during tumor necrosis factor-related activation-induced cytokine-mediated osteoclastogenesis.

Osteoclast differentiation from hematopoietic precursors is controlled by the tumor necrosis factor family member tumor necrosis factor-related activation-induced cytokine (TRANCE) via induction of various transcription factors, including nuclear factor of activated T cells (NFAT) c1. During osteoclast differentiation, NFATc1 is further activated via calcium signaling when costimulatory receptors expressed on osteoclast precursors, such as osteoclast-associated receptor (OSCAR), are stimulated. Here we show that NFATc1 expression precedes that of OSCAR during TRANCE-mediated osteoclastogenesis and that inhibition of NFATc1 by cyclosporin A abolishes TRANCE-induced OSCAR expression and subsequent osteoclast differentiation. Moreover, we show that the 1.0-kb promoter region of the OSCAR gene contains three potential NFATc1-binding sites. Induction of an OSCAR promoter-luciferase reporter is significantly increased when transiently transfected into 293T cells in combination with NFATc1 expression plasmid. Deletion and site-directed mutant constructs confirmed that NFATc1-binding sites are both functional and NFATc1-specific. Furthermore, NFATc1 synergistically activates an OSCAR reporter construct together with microphthalmia transcription factor and PU.1, transcription factors previously shown to be critical for osteoclast differentiation. In addition, a plasmid expressing constitutively active MAP kinase kinase 6 enhances the transactivation activity of NFATc1/microphthalmia transcription factor/PU.1 on the OSCAR promoter. Taken together, our results indicate that NFATc1 is an important transcription factor in the induction of OSCAR during osteoclastogenesis. Elucidation of NFATc1 as a transcription factor for OSCAR expression implies the presence of a positive feedback circuit of TRANCE-induced activation of NFATc1, involving NFATc1-mediated OSCAR expression and its subsequent activation of NFATc1, necessary for efficient differentiation of osteoclasts.

Animals↗

PubMed2005

Sorting method to extend the dynamic range of the Shack-Hartmann wave-front sensor.

We propose a simple and powerful algorithm to extend the dynamic range of a Shack-Hartmann wave-front sensor. In a conventional Shack-Hartmann wave-front sensor the dynamic range is limited by the f-number of a lenslet, because the focal spot is required to remain in the area confined by the single lenslet. The sorting method proposed here eliminates such a limitation and extends the dynamic range by tagging each spot in a special sequence. Since the sorting method is a simple algorithm that does not change the measurement configuration, there is no requirement for extra hardware, multiple measurements, or complicated algorithms. We not only present the theory and a calculation example of the sorting method but also actually implement measurement of a highly aberrated wave front from nonrotational symmetric optics.

Algorithms↗