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42
result(s) for
"Hye-Young Youn"
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Cornflower Extract and Its Active Components Alleviate Dexamethasone-Induced Muscle Wasting by Targeting Cannabinoid Receptors and Modulating Gut Microbiota
2024
Sarcopenia, a decline in muscle mass and strength, can be triggered by aging or medications like glucocorticoids. This study investigated cornflower (Centaurea cyanus) water extract (CC) as a potential protective agent against DEX-induced muscle wasting in vitro and in vivo. CC and its isolated compounds mitigated oxidative stress, promoted myofiber growth, and boosted ATP production in C2C12 myotubes. Mechanistically, CC reduced protein degradation markers, increased mitochondrial content, and activated protein synthesis signaling. Docking analysis suggested cannabinoid receptors (CB) 1 and 2 as potential targets of CC compounds. Specifically, graveobioside A from CC inhibited CB1 and upregulated CB2, subsequently stimulating protein synthesis and suppressing degradation. In vivo, CC treatment attenuated DEX-induced muscle wasting, as evidenced by enhanced grip strength, exercise performance, and modulation of muscle gene expression related to differentiation, protein turnover, and exercise performance. Moreover, CC enriched gut microbial diversity, and the abundance of Clostridium sensu stricto 1 positively correlated with muscle mass. These findings suggest a multifaceted mode of action for CC: (1) direct modulation of the muscle cannabinoid receptor system favoring anabolic processes and (2) indirect modulation of muscle health through the gut microbiome. Overall, CC presents a promising therapeutic strategy for preventing and treating muscle atrophy.
Journal Article
Prevalence and Virulence Characteristics of Enterococcus faecalis and Enterococcus faecium in Bovine Mastitis Milk Compared to Bovine Normal Raw Milk in South Korea
by
Jang, Yong-Seok
,
Youn, Hye-Young
,
Kang, Hye-Jeong
in
Antibacterial agents
,
Antibiotics
,
Antimicrobial agents
2022
Enterococcus spp. are pathogens that cause environmental mastitis and are difficult to eliminate owing to their resistance to antibiotics. To compare the virulence characteristics of isolates from bovine mastitis milk (BMM) and bovine normal raw milk (NRM), we isolated Enterococcus spp. from 39 dairy farms in South Korea from 2015–2020. A total of 122 Enterococcus spp. were identified, with Enterococcus faecalis (73.8%) accounting for the majority, followed by Enterococcus faecium (26.2%). E. faecalis isolated from BMM harbored gelE, asa1, esp, and cylA genes with a prevalence of 85.7, 71.4, 54.3, and 30.0%, respectively. These genes were significantly more abundant in BMM than in NRM, except for asa1 (p < 0.0001). Interestingly, strong biofilm and gelatinase formation was predominately observed for BMM isolates and this was significantly correlated to the presence of esp and gelE genes (p < 0.05). BMM isolates demonstrated higher resistance to tetracycline (59.3%), followed by chloramphenicol (21.0%), rifampicin (18.5%), doxycycline (4.9%), ciprofloxacin (1.2%), and nitrofurantoin (1.2%), than those from NRM. E. faecalis harboring esp, gelE, and cylA may be causative agents for bovine mastitis and act as a reservoir for the transmission of virulence factors to humans.
Journal Article
Host-specific effects of Eubacterium species on Rg3-mediated modulation of osteosarcopenia in a genetically diverse mouse population
2024
Background
Osteosarcopenia, characterized by the simultaneous loss of bone and muscle mass, is a serious health problem in the aging population. This study investigated the interplay between host genetics, gut microbiota, and musculoskeletal health in a mouse model of osteosarcopenia, exploring the therapeutic potential of gut microbiota modulation.
Methods
We examined the effects of Rg3, a phytochemical, on osteosarcopenia and its interactions with host genetics and gut microbiota in six founder strains of the Collaborative Cross (CC) population. Subsequently, we evaluated the therapeutic potential of Eubacterium nodatum (EN) and Eubacterium ventriosum (EV), two gut microbes identified as significant correlates of Rg3-mediated osteosarcopenia improvement, in selected C57BL/6 J (B6) and 129S1/SvImJ (129S1) mouse strains.
Results
Rg3 treatment altered gut microbiota composition aligned with osteosarcopenia phenotypes, which response varied depending on host genetics. This finding enabled the identification of two microbes in the
Eubacterium
genus, potential mediator of Rg3 effect on osteosarcopenia. Oral administration of EN and EV differentially impacted bone density, muscle mass, exercise performance, and related gene expression in a mouse strain-specific manner. In 129S1 mice, EN and EV significantly improved these parameters, effectively reversing osteosarcopenic phenotypes. Mechanistic investigations revealed that these effects were mediated through the modulation of osteoblast differentiation and protein degradation pathways. In contrast, EN and EV did not significantly improve osteosarcopenic phenotypes in B6 mice, although they did modulate mitochondrial biogenesis and microbial diversity.
Conclusions
Our findings underscore the complex interplay between host genetics and the gut microbiota in osteosarcopenia and emphasize the need for personalized treatment strategies. EN and EV exhibit strain-specific therapeutic effects, suggesting that tailoring microbial interventions to individual genetic backgrounds may be crucial for optimizing treatment outcomes.
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Video Abstract
Graphical Abstract
Journal Article
Modulation of muscle anabolism and gut microbiota by Polyporus umbellatus extract attenuates dexamethasone-induced muscle atrophy
2025
To investigate the pharmacological mechanisms by extract of
Polyporus umbellatus
(PU) protects against dexamethasone (DEX)-induced muscle atrophy, focusing on its direct effects on muscle cell signaling, mitochondrial function, oxidative stress, and its indirect influence via gut microbiota modulation. In
vitro
, DEX-treated C2C12 myotubes were used to assess PU’s effects on cell viability, myotube morphology, myogenic/atrophy gene expression, Akt/mTOR/FoxO3a signaling pathways, mitochondrial function, and oxidative stress. In
vivo
, a DEX-induced muscle atrophy mouse model was employed to evaluate the efficacy of orally administered PU and
L. gasseri
(ATCC 19992) alone on muscle mass, strength, exercise performance, and gene expression. Gut microbiota composition was analyzed via 16 S rRNA sequencing, with predicted microbial enzyme functions and correlations to muscle parameters examined. In
vitro
, PU significantly attenuated DEX-induced C2C12 myotube atrophy, activated Akt/mTOR signaling, inhibited FoxO3a signaling, mitigated oxidative stress, and enhanced mitochondrial function. In vivo, PU dose-dependently improved grip strength, muscle mass, and exercise performance in DEX-treated mice, concurrently upregulating myogenic and mitochondrial biogenesis genes. PU treatment significantly modulated gut microbial diversity and composition, notably increasing
L. gasseri
abundance. Oral administration
L. gasseri
recapitulated PU’s protective effects on muscle phenotype, gene expression, and gut microbiota modulation.
L. gasseri
levels and predicted microbial D-lactate dehydrogenase activity correlated positively with muscle health. However, bioactivity-guided fractionation of PU did not identify a single predominant active compound. In conclusion, PU protects against glucocorticoid-induced muscle atrophy through a dual mechanism involving direct muscle-protective actions and beneficial modulation of the gut microbiota, partly mediated by enrichment and direct effects of
L. gasseri
.
Graphical Abstract
Journal Article
Conformal and Transparent Al2O3 Passivation Coating via Atomic Layer Deposition for High Aspect Ratio Ag Network Electrodes
by
Sung-Nam Lee
,
Hye-Young Youn
,
Han-Ki Kim
in
Ag network
,
Al2O3 passivation
,
Al2O3 passivation; atomic layer deposition; Ag network; high aspect ratio; stability; thin-film heaters
2023
We demonstrated conformal Al2O3 passivation via atomic layer deposition (ALD) of a flexible Ag network electrode possessing a high aspect ratio. The Ag network electrode passivated by the ALD-grown Al2O3 film demonstrated constant optical transmittance and mechanical flexibility relative to the bare Ag network electrode. Owing to the conformal deposition of the Al2O3 layer on the high aspect ratio Ag network electrode, the electrode exhibited more favorable stability than its bare Ag-network counterpart. To demonstrate the feasibility of Al2O3 passivation via ALD on a flexible Ag network, the performances of flexible and transparent thin-film heaters (TFHs) with both a bare Ag network and that passivated by ALD-grown Al2O3 were compared. The performance of Al2O3/Ag network-based TFHs was minimally altered even after harsh environmental tests at 85% relative humidity and a temperature of 85 °C, while the performance of bare electrode-based TFHs significantly deteriorated. The improved stability and reliability of the Al2O3/Ag network-based TFHs indicate that the ALD-grown Al2O3 film effectively prevents the introduction of moisture and impurities into the Ag network with a high aspect ratio. The improvement in the stability of the Ag network through Al2O3 passivation implies that the ALD-grown Al2O3 film represents a promising transparent and flexible thin film passivation material for high quality Ag network electrodes with high aspect ratios.
Journal Article
A Combined In Vitro and In Vivo Assessment of the Safety of the Yeast Strains Kluyveromyces marxianus A4 and A5 Isolated from Korean Kefir
by
Jang, Yong-Seok
,
Youn, Hye-Young
,
Seo, Kun-Ho
in
Animal models
,
Animals
,
anti-inflammatory activity
2023
Kefir is a traditional fermented milk containing beneficial bacteria and yeasts. Despite
Kluyveromyces marxianus
, isolated from kefir
,
gaining increasing attention as a potential probiotic yeast owing to its biological function,
Saccharomyces boulardii
is the only species considered as a probiotic yeast. We evaluated the safety of
K
.
marxianus
strains A4 and A5
,
isolated from Korean kefir, in comparison with that of
S
.
boulardii.
Virulence attributes were preliminarily assessed in vitro including their ability of gelatin hydrolysis, pseudohyphae formation, and hemolysis. To evaluate in vivo safety, the strains were challenged in a healthy animal model, four-week-old female BALB/c mice. Mice were orally administered 0.2 mL of 0.9% sterilized saline (NC_S;
n
= 6),
S. boulardii
ATCC MYA-796 (high concentration, S.b_H; low concentration, S.b_L;
n
= 6 for each),
K. marxianus
A4 (high concentration, A4_H; low concentration, A4_L;
n
= 6 for each), or
K. marxianus
A5 (high concentration, A5_H; low concentration, A5_L;
n
= 6 for each) for 2 weeks. At study end, body weight, spleen and liver weights, and blood parameters were assessed.
K. marxianus
A4 and A5 were tested negative for gelatinase and hemolysis. Overall, hematological, plasma biochemical, and cytokine (interleukin-1β and tumor necrosis factor-α) parameters were comparable between the experimental and negative control (NC) groups. Notably, the interleukin-6 level of the A5_H group was significantly lower than that of the NC group (
p
< 0.05), suggesting anti-inflammatory potential of
K. marxianus
A5.
Journal Article
Gut microbiota modulation via short-term administration of potential probiotic kefir yeast Kluyveromyces marxianus A4 and A5 in BALB/c mice
2023
Kefir yeast,
Kluyveromyces marxianus
, has been evaluated for its potential probiotic properties—survivability, non-pathogenicity, and antioxidant and anti-microbial activities. However, host gut microbiota modulation of kefir yeasts remains unclear. Here, we compared kefir yeast strains
K
.
marxianus
A4 (Km A4) and
K. marxianus
A5 (Km A5) with
Saccharomyces boulardii
ATCC MYA-796 (Sb MYA-796) by investigating their adherence to colorectal adenocarcinoma (Caco-2) cells and gut microbiota modulation in BALB/c mice. The kefir yeast strains exhibited higher intestinal cell adhesion than Sb MYA-796 (
p
< 0.05). Bacteroidetes, Bacteroidales, and
Bacteroides
were more abundant in the 1 × 10
8
CFU/mL of Km A4 treatment group than in the control group (
p
< 0.05). Moreover, 1 × 10
8
CFU/mL of Km A5 increased Corynebacteriales and
Corynebacterium
compared to the 1 × 10
8
CFU/mL of Km A4 treatment group (
p
< 0.01). The results showed that Km A4 and Km A5 had good Caco-2 cell adhesion ability and modulated gut microbiota upon short-term administration in healthy mice.
Journal Article
Conformal and Transparent Alsub.2Osub.3 Passivation Coating via Atomic Layer Deposition for High Aspect Ratio Ag Network Electrodes
2023
We demonstrated conformal Al[sub.2]O[sub.3] passivation via atomic layer deposition (ALD) of a flexible Ag network electrode possessing a high aspect ratio. The Ag network electrode passivated by the ALD-grown Al[sub.2]O[sub.3] film demonstrated constant optical transmittance and mechanical flexibility relative to the bare Ag network electrode. Owing to the conformal deposition of the Al[sub.2]O[sub.3] layer on the high aspect ratio Ag network electrode, the electrode exhibited more favorable stability than its bare Ag-network counterpart. To demonstrate the feasibility of Al[sub.2]O[sub.3] passivation via ALD on a flexible Ag network, the performances of flexible and transparent thin-film heaters (TFHs) with both a bare Ag network and that passivated by ALD-grown Al[sub.2]O[sub.3] were compared. The performance of Al[sub.2]O[sub.3]/Ag network-based TFHs was minimally altered even after harsh environmental tests at 85% relative humidity and a temperature of 85 °C, while the performance of bare electrode-based TFHs significantly deteriorated. The improved stability and reliability of the Al[sub.2]O[sub.3]/Ag network-based TFHs indicate that the ALD-grown Al[sub.2]O[sub.3] film effectively prevents the introduction of moisture and impurities into the Ag network with a high aspect ratio. The improvement in the stability of the Ag network through Al[sub.2]O[sub.3] passivation implies that the ALD-grown Al[sub.2]O[sub.3] film represents a promising transparent and flexible thin film passivation material for high quality Ag network electrodes with high aspect ratios.
Journal Article
Unraveling ER dimerization dynamics in endocrine disruption based on a BRET-focused approach
2025
Endocrine-disrupting chemicals (EDCs) are exogenous compounds that interact with the estrogen receptor (ER), thereby disrupting estrogen-mediated signaling. In a previous study, we employed a bioluminescence resonance energy transfer (BRET) system to assess ER dimerization for detecting EDCs. To further determine whether the BRET assay could be used independently to identify EDCs, we investigated ER-EDC interactions before and after dimerization. Results from isothermal titration calorimetry (ITC) and dynamic light scattering (DLS) revealed that ER dimerization can be mediated by EDCs. Consequently, the BRET assay proved effective in detecting dimerization and clarifying its relevance to EDC-induced signaling disruption. Additionally, to examine EDC-induced transcriptional changes, we performed chromatin immunoprecipitation sequencing (ChIP-seq), followed by gene ontology (GO) analysis. These analyses demonstrated that EDCs affect various signaling pathways, including those involved in antibody-dependent cytotoxicity, bone morphogenetic protein (BMP) signaling in cardiac induction, and hepatocyte growth factor receptor signaling. Overall, this study elucidates the molecular mechanisms by which EDCs influence ER dimerization and signaling. These findings highlight the utility of the BRET-based assay for EDC detection and contribute to a deeper understanding of the systemic effects of EDCs on endocrine disruption.
Journal Article
Self-service technologies (SSTs) in airline services: multimediating effects of flow experience and SST evaluation
2022
Purpose
This study aims to investigate the effects of consumers’ motivations on behavioral intention to use self-service technology (SST) in airline services exploring multimediating effects of flow experience and SST evaluation in Stimulus-Organism-Response model.
Design/methodology/approach
An online survey was conducted with quota sampling based on age group who had experiences of SSTs usage at the Incheon International Airport in South Korea. A total of 286 responses were used for the data analysis with structural equation modeling to examine the proposed model and the multimediating effects.
Findings
The results showed that consumers’ intrinsic and extrinsic motivations had positive impacts on their flow experience, SST evaluation and behavioral intention to use airline SSTs. Their flow experience had a positive influence on SST evaluation, and their SST evaluation influenced behavioral intention to use airline SSTs. Consumers’ flow experience and SST evaluation mediated the relationship between intrinsic and extrinsic motivations and behavioral intention to use airline SSTs.
Practical implications
It is important for customers to perceive extrinsic motivation such as speed, convenience and efficiency for the smooth process of airline SSTs at the airport. SST evaluation plays a key role to increase customers’ behavioral intention to use airline SSTs.
Originality/value
This study extends the understanding of consumers’ intrinsic and extrinsic motivations, flow experience, SST evaluation and behavioral intentions to use SST in airline services by building on a model. Especially, findings of the (multi)mediating effects of customers’ perceived flow and SST evaluation on the relationship between motivations and behavioral intention to use airline SSTs might provide better guidelines for managers to incorporate SSTs, to increase operational efficiency and to boost customer experiences.
Journal Article