Explore the vast range of titles available.

Background This study aimed to investigate the relationships between the frequency of impairments in daily activities due to the overuse of the Internet, gaming, or smartphones (IGS) and sociodemographic characteristics, social relationships (including family) & activities, psychosocial characteristics, health status, and health-related quality of life (HRQoL) of Korean adults. Methods Secondary data from the 2017 Community Health Survey, a large-scale sample survey conducted yearly in South Korea, were analyzed for 190,066 adults over 19 years of age. Three categories were created for impairment groups due to IGS overuse: No Impairment, Mild Impairment, and Moderate-to-Severe groups. And between-group differences were examined using a one-way ANOVA for health status measured with the EQ-5D-3 L and chi-square tests for all categorical dependent variables, which included sociodemographic characteristics, social relationships & activities, and psychosocial factors. The association between frequencies of daily activity impairments due to IGS overuse and the dependent variables were examined using a multivariate logistic regression analysis and a linear regression model. Results Approximately 21,345 (11.23%) of the 190,066 participants reported experiencing impairments in daily activities due to IGS overuse at least once in the previous year and the impairments were more severe in males than females. Participants experiencing impairments in daily activities contacted their friends a significantly higher number of times (4 times or more per month) and engaged in leisure activities more frequently (more than once per month) than those without impairments. There was also a significant positive relationship between IGS overuse and stress, depression, suicidal ideation, and suicide attempts. Among participants aged 19–64, impairments in daily activities due to IGS overuse were associated with a lower HRQoL. Conversely, for those aged 65 and over, mild and moderate-to-severe impairments due to IGS overuse were associated with a significantly higher HRQoL. Conclusions Increased impairments in daily activities due to IGS overuse may negatively affect mental health. However, among older adults, the frequency of such impairments was positively associated with HRQoL. This finding could be considered to apply interventions with Internet usage or ICT devices for older adults to enhance their quality of life.

Diabetes mellitus (DM) characterized by hyperglycemia is a chronic metabolic disorder that leads to many symptoms and vascular complications. Despite the close association between DM and cancer progression, the response and role of endothelial cells (ECs) under diabetic conditions in tumor metastasis remain to be elucidated. In this study, we sought to determine whether and how ECs under diabetic conditions contribute to tumor metastasis. We have taken advantage of syngeneic mouse tumor models of Lewis lung carcinoma (LLC) and melanoma (B16F10) cells and a streptozotocin (STZ)-induced hyperglycemia model. We demonstrated that hyperglycemia increased the metastasis of LLC and B16F10 cells in an experimental metastasis model with an intravenous injection of the tumor cells. We also found that hyperglycemia promoted lung metastasis of tumor cells by increasing the adhesiveness of ECs to facilitate the adhesion of tumor cells to ECs rather than affecting the metastatic behavior of tumor cells themselves. From the analysis of gene expression in primary lung ECs from STZ-treated mice, we identified that vWF promoted the adhesion of tumor cells to ECs and the transendothelial migration of tumor cells. Mechanistically, hyperglycemia-induced oxidative stress in ECs, and increased oxidative stress enhanced vWF expression in ECs through an increase in the transcription factor GATA1. These results provide evidence for the role of vWF in ECs in promoting hyperglycemia-induced tumor metastasis and potential therapeutic targets for the regulation of vWF expression in ECs and hyperglycemia-induced tumor metastasis.

In this paper, we study the discrete Cucker–Smale model with a unit-speed constraint. For this, we first propose a discrete-time approximation of the Cucker–Smale model with a unit speed constraint (Choi and Ha, in: Commun Math Sci 14:953–972, 2016) using an exponential map in the state space Rd×Sd-1. Then, we present several sufficient frameworks to guarantee its asymptotic flocking. Moreover, we prove the finite-in-time transition from the discrete system to its continuous counterpart under generic initial data and system parameters. With the help of this result and the asymptotic flocking of the discrete and continuous systems, we also demonstrate the uniform-in-time transition between them.

In this paper, we study the discrete Cucker–Smale model with a unit-speed constraint. For this, we first propose a discrete-time approximation of the Cucker–Smale model with a unit speed constraint (Choi and Ha, in: Commun Math Sci 14:953–972, 2016) using an exponential map in the state space R d × S d - 1 . Then, we present several sufficient frameworks to guarantee its asymptotic flocking. Moreover, we prove the finite-in-time transition from the discrete system to its continuous counterpart under generic initial data and system parameters. With the help of this result and the asymptotic flocking of the discrete and continuous systems, we also demonstrate the uniform-in-time transition between them.

Background: The aim of this study was to evaluate the impact of the 2016 Gyeongju Earthquake on the stress perception, depressive symptoms, and health-related quality of life (HRQoL) among Gyeongju residents. Methods: This study was a secondary analysis of the 2015–2017 Korean Community Health Survey undertaken in the disaster area, Gyeongju, and in controlled areas, Sangju and Yangju, which had varying seismic intensities. Pearson’s chi-square test, ANCOVA and two-way ANOVA were performed. Results: The stress perception rate and anxiety/depression in the 5th dimension of the EuroQul-five-dimensions three-level version (EQ-5D-3L) in Gyeongju was significantly higher in 2017 than in 2016. As for the HRQoL, the controlled regions showed a tendency to increase in 2017 rather than in 2016, while Gyeongju had no significant differences during 2015 and 2017. As a result, Gyeongju had the lowest HRQoL in 2017. Conclusion: Mental health in the disaster area after the 2016 earthquake was worse, and the HRQoL of Gyeongju residents was relatively lower than the control regions. Based on the results of the study, government agencies should remain interested in developing a post-disaster psychological support program for disaster survivors at a community level.

Extrusion with an intermeshing corotating twin-screw extruder with a limited amount of water caused structural changes in corn starch. The structural changes resulted in a transformation-from a semicrystalline to an amorphous state and the development of orientation of molecular chains in the amorphous region during extrusion. These structural changes, in turn, caused an increase in theTg, tensile strength, and resilience of the extruded corn starch. Our experimental results showed that the tensile properties and resilience of the expanded corn starch extruded at 240‡C were the best: tensile strength, 1.7 kPa; tensile modulus, 40.4 kPa; and resilience, 57.2%. Extrusion produced an expanded corn starch suitable for protective loose-fill.

CHI3L1, a chitinase-like protein, is a potent immune modulator involved in various diseases, including lung cancer. While recent studies have demonstrated that kasugamycin (KSM) is a pan-chitinase inhibitor with strong anti-fibrotic activity, its effects on specific chitinase-like proteins remain undefined. This study shows that KSM effectively abrogates CHI3L1-stimulated cellular signaling and bioactivities. In a B16/F10 melanoma lung metastasis model, where CHI3L1 plays a critical role, KSM treatment significantly reduced melanoma lung metastasis dose-dependently. The anti-tumor effect of KSM was found to be CHI3L1-specific, as CHI3L1 overexpression enhanced melanoma lung colony formation, which was effectively blocked by KSM. In melanoma-challenged lungs, KSM treatment significantly reduced the elevation of M2 macrophages expressing CD206, CD163, and PD-L1. In studies using human monocytic THP-1 cells, CHI3L1 promoted M2 macrophage differentiation, which KSM significantly suppressed. Bulk RNA sequencing of differentiated macrophages revealed that CHI3L1 highly induced the expression of epidermal growth factor receptor (EGFR), and this induction was counter-regulated by KSM, and CHI3L1-driven M2 macrophage activation was reduced with EGFR blocker treatment. These findings reveal a novel anti-tumor mechanism of KSM, which inhibits M2-like tumor-associated macrophage differentiation, potentially through the CHI3L1-EGFR axis.

CHI3L1, a chitinase-like protein, plays a key role in the pathogenesis of pulmonary fibrosis, though the precise mechanisms remain unclear. This study explores how CHI3L1 regulates profibrotic macrophage activation and invasive myofibroblast differentiation and their interactions. In vitro, CHI3L1 induced profibrotic M2 macrophage activation and differentiation marked by increased expression of CD163, CD206, and PD-L1. CHI3L1 also enhanced TGF-β1 effects on lung fibroblasts including myofibroblast transformation, migration and tissue invasion. Mechanistically, CHI3L1 increased TGF-β1-stimulation of Smad, Akt and Erk signaling and PD-L1 played a significant role in TGF-β1/CHI3L1-stimulated myofibroblast transformation. Coculture experiment further confirmed the ability of CHI3L1 to induce profibrotic macrophage activation that enhanced myofibroblast transformation mediated via a CD44-PD-L1 axis. Following in vivo bleomycin challenge, CHI3L1 transgenic mice exhibited significantly higher levels of PD-L1+ M2 macrophages, PD-L1+/PDGFRα+ fibroblasts and increased numbers of PD-1+ and CD45+/PD-1+ cells compared to wild-type controls. Notably, combined treatment with anti-CHI3L1 and anti-PD-1 antibodies, or a bispecific anti-CHI3L1-anti-PD-1 antibody, resulted in greater inhibition of bleomycin-induced fibrosis than either antibody alone. These findings suggest that there is a stimulatory interaction between CHI3L1 and the PD-1/PD-L1 axis in promoting profibrotic macrophage activation and invasive fibroblast differentiation. The results also highlight the potential of bispecific targeting of CHI3L1 and the PD-1/PD-L1 pathway as an effective therapeutic approach for pulmonary fibrosis.

This dissertation consists of four sections. The first section describes the synthesis of methyl 4a-carba-D-galactofuranosides. Oligosaccharides containing furanose moieties are important constituents of the cell wall of Mycobacterium tuberculosis, the intracellular causative bacterial pathogen of tuberculosis. A polysaccharide, arabinogalactan, attached to long chain lipids called mycolic acids, in combination with glycolipids found at the periphery of the cell wall envelope, provide a very efficient hydrophobic barrier that prevents the intrusion of drugs into the microorganism. Compounds that interfere with the biosynthesis of the arabinogalactan are therefore potential anti-tuberculosis agents. All arabinose and galactose residues of the arabinogalactan are found in the furanose form. Because furanose polysaccharides are critical for the survival of mycobacteria, the enzymes responsible for the biosynthesis of mycobacterial cell wall are very promising targets for drug action. A route for the synthesis of metabolically stable carbasugar analogs of galactofuranosides, was developed from D-galactose by using ring-closing metathesis as a key transformation. The second section, which is related to the first section in that it is focused on the identification of new anti-tuberculosis agents, details the synthesis of C-glycosidic glycopeptides. A series of C-arabinosyl glycopeptides was synthesized by solid-phase peptide synthesis. The Fmoc-protected arabinofuranoside building block was prepared from D-arabinose. The key transformations were Homer-Emmons olefination and catalytic asymmetric hydrogenation of resulting enamide ester. The synthesized dipeptides will be screened for their ability to inhibit arabinosyltransferases involved in mycobacterial cell wall assembly. The third section reports the synthesis of buergerinin F and buergerinin G, recently isolated from a plant Scrophularia buergeriana. The synthesis of buergerinin F and G was achieved from thymidine. We were able to establish the structures and absolute stereochemistry of these natural products. The final section addresses studies towards the synthesis of feigrisolide B, a seven-membered lactone isolated from fungi Streptomyces griseus . The synthetic study includes coupling reaction of two key intermediates and deoxygenation protocol developed in our group. Three more steps from the prepared intermediate would provide feigrisolide B.

Salt marshes are known as major blue carbon ecosystems for their higher carbon sequestration capacity and productivity compared to terrestrial ecosystems. However, in Korea, salt marshes have been continuously decreasing since the 1980s. This study aims to identify seasonal changes in salt marsh plants and evaluate the carbon and nitrogen sequestration in these ecosystems. This study observed seasonal changes in the biomass, cover, height, photosynthetic efficiency, carbon and nitrogen content of Suaeda japonica in two salt marsh ecosystems in Incheon, Korea, Yeongjong (YJ) and Sorae (SR). In spring, plant density at SR. was significantly higher than at YJ. This higher density at SR inhibited growth and survival during summer and autumn. In addition, photosynthetic efficiency at SR decreased significantly in summer compared to spring. The different habitat densities between the two sites resulted in morphological variations. The plants at YJ, with lower density, grew wider with more branches and showed higher dry weight in comparison to those at SR. Carbon sequestration by S. japonica per unit area was 113.70 g/m 2 at YJ, which was twice as high as at SR. The plant density and biomass of S. japonica were affected by differences in seawater inflow at each site. The tissue carbon content was highest in the roots, suggesting that carbon absorbed by the leaves is effectively stored in sediment. This study provides insights into the regional and seasonal changes of S. japonica , highlighting its significance as a blue carbon resource. The results can contribute to the evaluation and restoration of salt marshes to enhance their carbon sequestration potential.