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23 result(s) for "Kim, Seong-Yeop"
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One-Step Fabrication of Microfluidic Channels in Polydimethylsiloxane: Influence of Laser Power on Channel Formation
Recent advancements in microfluidic technologies have revolutionized their applications, particularly in drug monitoring, continuous biochemical analysis, and real-time physiological assessments. However, the fabrication of microfluidic devices with precise flow control remains constrained by either cost-prohibitive photolithography processes or limited-precision 3D printing techniques. In this study, we propose a one-step fabrication method employing picosecond laser processing to directly create microfluidic channels in (PDMS). This method achieves micron-scale channel precision while significantly simplifying the fabrication process and reducing costs. This approach eliminates the need for additional encapsulation steps, further reducing contamination risks and improving production scalability. These findings highlight the potential of this fabrication method to advance next-generation wearable biochemical devices and personalized healthcare technologies.
Acinetobacter baumannii under Acidic Conditions Induces Colistin Resistance through PmrAB Activation and Lipid A Modification
Colistin is a last-resort antimicrobial agent for treating carbapenem-resistant Acinetobacter baumannii infections. The activation of PmrAB by several environmental signals induces colistin resistance in Gram-negative bacteria. This study investigated the molecular mechanisms of colistin resistance in A. baumannii under acidic conditions using wild-type (WT) A. baumannii 17978, ΔpmrA and ΔpmrB mutants, and pmrA-complemented strains. The pmrA or pmrB deletion did not affect the growth of A. baumannii under acidic or aerobic conditions. A. baumannii under acidic (pH 5.5) and high-iron (1 mM) conditions showed 32- and 8-fold increases in the minimum inhibitory concentrations (MICs) of colistin, respectively. The ΔpmrA and ΔpmrB mutants at pH 5.5 showed a significant decrease in colistin MICs compared to the WT strain at pH 5.5. No difference in colistin MICs was observed between WT and mutant strains under high-iron conditions. The pmrCAB expression significantly increased in the WT strain at pH 5.5 compared to the WT strain at pH 7.0. The pmrC expression significantly decreased in two mutant strains at pH 5.5 compared to the WT strain at pH 5.5. The PmrA protein was expressed in the ΔpmrA strain carrying ppmrA_FLAG plasmids at pH 5.5 but not at pH 7.0. Lipid A modification by the addition of phosphoethanolamine was observed in the WT strain at pH 5.5. In conclusion, this study demonstrated that A. baumannii under acidic conditions induces colistin resistance via the activation of pmrCAB operon and subsequent lipid A modification.
The Tomato Juhwang Mutant Accumulates a High Level of β-Carotene and has a Long Shelf-Life
Carotenoids have diverse functions in plants and animals. In tomato ( Solanum lycopersicum ), the red color of fruits is due to the accumulation of the carotenoid lycopene during fruit ripening. Here, the effect of a new recessive mutation juhwang ( jh ) on fruit color and shelf life was investigated during fruit ripening. The prominent phenotype of jh plants was orange fruit color. Carotenoid analysis revealed that jh fruits had lower lycopene and higher β-carotene levels than those in wild-type fruits after the fruit ripening stage. Expression analysis of carotenoid biosynthetic genes showed that the gene encoding lycopene-ε-cyclase was upregulated and the β-carotene hydroxylase 2 gene was significantly downregulated in jh fruits compared with those in wild-type fruits during ripening. jh fruits also had a longer shelf-life than that of wild-type fruits based on the increased firmness. The gene expression patterns and levels of 1-aminocyclopropane-1-carboxylic acid synthases, pectate lyase, and polygalacturonase, which are fruit ripening and cell wall-softening-related genes, were delayed and reduced in jh fruits during fruit ripening compared with those in wild-type fruits. Therefore, jh may represent a novel gene, and these plants may serve as an important genetic resource to study fruit ripening related to carotenoids and shelf-life.
Therapeutic Potential of Mangosteen Pericarp Extract-Loaded Liposomes against Superficial Skin Infection Caused by Staphylococcus pseudintermedius in a Murine Model
α-mangostin (α-MG) demonstrates antibacterial activity against Staphylococcus species. Therefore, this study aimed to explore the antibacterial activity of α-MG-rich mangosteen pericarp extract (MPE)-loaded liposomes against Staphylococcus isolates from companion animal skin diseases in vitro and evaluated their therapeutic potential in a murine model of superficial skin infection caused by S. pseudintermedius. α-MG-rich extract was purified from mangosteen pericarp and then complexed with γ-cyclodextrin (γ-CD), forming the inclusion complexes. Nanoliposomes containing MPE and γ-CD complexes were prepared by adding lecithin and casein. Minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of MPE-loaded liposomes were determined using agar dilution and broth microdilution methods. The therapeutic potential of MPE-loaded liposomes was evaluated in vivo on tape-stripped skin lesions infected with S. pseudintermedius. Purified MPE and MPE-loaded liposomes contained 402.43 mg/g and 18.18 mg/g α-MG, respectively. MPE-loaded liposomes showed antibacterial activity against clinical Staphylococcus isolates in vitro but did not show antibacterial activity against Gram-negative bacterial isolates. MPE-loaded liposomes demonstrated consistent MICs and MBCs against Staphylococcus isolates. These liposomes significantly reduced bacterial numbers and lesional sizes in a superficial skin infection model. Moreover, they reconstructed the epidermal barrier in skin lesions. The therapeutic concentrations of MPE-loaded liposomes did not induce cytotoxicity in canine progenitor epidermal keratinocyte cells. In conclusion, MPE-loaded liposomes hold promise for the development of a prospective topical formulation to treat superficial pyoderma in companion animals.
Antimicrobial activity of α-mangostin against Staphylococcus species from companion animals in vitro and therapeutic potential of α-mangostin in skin diseases caused by S. pseudintermedius
Antimicrobial resistance in Staphylococcus species from companion animals is becoming increasingly prevalent worldwide. S. pseudintermedius is a leading cause of skin infections in companion animals. α-mangostin (α-MG) exhibits various pharmacological activities, including antimicrobial activity against G (+) bacteria. This study investigated the antimicrobial activity of α-MG against clinical isolates of Staphylococcus species from companion animals and assessed the therapeutic potential of α-MG in skin diseases induced by S. pseudintermedius in a murine model. Furthermore, the action mechanisms of α-MG against S. pseudintermedius were investigated. α-MG exhibited antimicrobial activity against clinical isolates of five different Staphylococcus species from skin diseases of companion animals in vitro , but not G (-) bacteria. α-MG specifically interacted with the major histocompatibility complex II analogous protein (MAP) domain-containing protein located in the cytoplasmic membrane of S. pseudintermedius via hydroxyl groups at C-3 and C-6. Pretreatment of S. pseudintermedius with anti-MAP domain-containing protein polyclonal serum significantly reduced the antimicrobial activity of α-MG. The sub-minimum inhibitory concentration of α-MG differentially regulated 194 genes, especially metabolic pathway and virulence determinants, in S. pseudintermedius . α-MG in pluronic lecithin organogel significantly reduced the bacterial number, partially restored the epidermal barrier, and suppressed the expression of cytokine genes associated with pro-inflammatory, Th1, Th2, and Th17 in skin lesions induced by S. pseudintermedius in a murine model. Thus, α-MG is a potential therapeutic candidate for treating skin diseases caused by Staphylococcus species in companion animals.
IAcinetobacter baumannii/I under Acidic Conditions Induces Colistin Resistance through PmrAB Activation and Lipid A Modification
Colistin is a last-resort antimicrobial agent for treating carbapenem-resistant Acinetobacter baumannii infections. The activation of PmrAB by several environmental signals induces colistin resistance in Gram-negative bacteria. This study investigated the molecular mechanisms of colistin resistance in A. baumannii under acidic conditions using wild-type (WT) A. baumannii 17978, ΔpmrA and ΔpmrB mutants, and pmrA-complemented strains. The pmrA or pmrB deletion did not affect the growth of A. baumannii under acidic or aerobic conditions. A. baumannii under acidic (pH 5.5) and high-iron (1 mM) conditions showed 32- and 8-fold increases in the minimum inhibitory concentrations (MICs) of colistin, respectively. The ΔpmrA and ΔpmrB mutants at pH 5.5 showed a significant decrease in colistin MICs compared to the WT strain at pH 5.5. No difference in colistin MICs was observed between WT and mutant strains under high-iron conditions. The pmrCAB expression significantly increased in the WT strain at pH 5.5 compared to the WT strain at pH 7.0. The pmrC expression significantly decreased in two mutant strains at pH 5.5 compared to the WT strain at pH 5.5. The PmrA protein was expressed in the ΔpmrA strain carrying ppmrA_FLAG plasmids at pH 5.5 but not at pH 7.0. Lipid A modification by the addition of phosphoethanolamine was observed in the WT strain at pH 5.5. In conclusion, this study demonstrated that A. baumannii under acidic conditions induces colistin resistance via the activation of pmrCAB operon and subsequent lipid A modification.
Disaster-Related Injury Management: High Prevalence of Wound Infection After Super Typhoon Haiyan
After Super Typhoon Haiyan, a category 5 tropical cyclone, insufficient resources were available for medical management. Many patients in the Philippines were wounded as a result of the disaster. We examined the prevalence, risk factors, and consequences of disaster-related wounds and wound infection in the post-disaster period. We performed a retrospective review of consecutive patients admitted to a Korean Disaster Relief Team clinic at St. Paul's Hospital, Tacloban City, Republic of Philippines, between December 9 and 13, 2013. Traumatic injury patients were included; patients not exhibiting a wound were excluded. Of the 160 patients enrolled in the study, 71 (44.4%) had infected wounds. There were no significant differences in the age, sex, past medical history, wound site, wound depth, injury mechanism, or inducer of injury between the uninfected and infected groups. In the univariate analysis, a foreign-body-contaminated wound, a chronic wound, elapsed time from injury to medical contact, an inadequately cared for wound, and need for subsequent wound management were associated with wound infection (P<0.05). The multivariate analysis revealed that foreign body contamination and having an inadequately cared for wound were associated with wound infection (odds ratio [OR]: 10.12, 95% confidence interval [CI]: 3.59-28.56; OR: 3.51, 95% CI: 1.07-11.51, respectively). In the post-disaster situation, many wound infections required definitive care. Wound infection was associated with inadequately cared for wounds and foreign-body-contaminated wounds.
Probiotic Lactobacillus fermentum strain JDFM216 improves cognitive behavior and modulates immune response with gut microbiota
Increasing evidence indicates that alterations in gut microbiota are associated with mammalian development and physiology. The gut microbiota has been proposed as an essential player in metabolic diseases including brain health. This study aimed to determine the impact of probiotics on degenerative changes in the gut microbiota and cognitive behavior. Assessment of various behavioral and physiological functions was performed using Y-maze tests, wheel running tests, accelerated rotarod tests, balance beam tests, and forced swimming tests (FSTs), using adult mice after 50 weeks of administering living probiotic bacterium Lactobacillus fermentum strain JDFM216 or a vehicle. Immunomodulatory function was investigated using immune organs, immune cells and immune molecules in the mice, and gut microbiota was also evaluated in their feces. Notably, the L. fermentum JDFM216-treated group showed significantly better performance in the behavior tests (P < 0.05) as well as improved phagocytic activity of macrophages, enhanced sIgA production, and stimulated immune cells (P < 0.05). In aged mice, we observed decreases in species belonging to the Porphyromonadaceae family and the Lactobacillus genus when compared to young mice. While administering the supplementation of L. fermentum JDFM216 to aged mice did not shift the whole gut microbiota, the abundance of Lactobacillus species was significantly increased (P < 0.05). Our findings suggested that L. fermentum JDFM216 also provided beneficial effects on the regulation of immune responses, which has promising implications for functional foods. Taken together, L. fermentum JDFM216 could confer the benefit of improving health with enhanced cognition, physiological behavior, and immunity by modulating the gut microbiota.
Probiotic Lactobacillus fermentum strain JDFM216 stimulates the longevity and immune response of Caenorhabditis elegans through a nuclear hormone receptor
Here, we examined the functionality of Lactobacillus fermentum strain JDFM216, a newly isolated probiotic bacterium, using a Caenorhabditis elegans model. We determined bacterial colonization in the intestinal tract of C. elegans by plate counting and transmission electron microscopy and examined the survival of C. elegans using a solid killing assay. In addition, we employed DNA microarray analysis, quantitative real time-polymerase chain reaction, and immunoblotting assays to explore health-promoting pathways induced by probiotic bacteria in C. elegans . Initially, we found that the probiotic bacterium L. fermentum strain JDFM216 was not harmful to the C. elegans host. Conditioning with JDFM216 led to its colonization in the nematode intestine and enhanced resistance in nematodes exposed to food-borne pathogens, including Staphylococcus aureus and Escherichia coli O157:H7. Interestingly, this probiotic strain significantly prolonged the life span of C. elegans . Whole-transcriptome analysis and transgenic worm assays revealed that the health-promoting effects of JDFM216 were mediated by a nuclear hormone receptor (NHR) family and PMK-1 signaling. Taken together, we described a new C. elegans -based system to screen novel probiotic activity and demonstrated that preconditioning with the probiotic L. fermentum strain JDFM216 may positively stimulate the longevity of the C. elegans host via specific pathway.
Efficient Interleaver Architecture for Modern Global Navigation Satellite Systems
In modern Global Navigation Satellite Systems (GNSS), interleavers are essential for improving system performance. However, limited research has focused on interleaver hardware optimization specifically for GNSS, primarily due to GNSS authorities strictly adhering to Interface Control Documents (ICDs), which discourage significant deviations in hardware implementations. Traditional GNSS interleavers employ double buffering and typically require extensive hardware resources, specifically 2N registers and 2(N− 1) + 1 multiplexers (MUXs), leading to increased complexity, power consumption, and latency. To bridge this gap, this paper presents a novel and efficient interleaver hardware architecture optimized specifically for modern GNSS by leveraging Lifetime Analysis and Forward–Backward Register Allocation. Lifetime Analysis precisely identifies the minimum number of registers necessary, and Forward–Backward Register Allocation ensures efficient utilization of these resources under continuous operation. Experiments were conducted for all seven currently used GNSS interleaving configurations. Synthesis results, obtained using a standard 28 nm Complementary Metal-Oxide Semiconductor (CMOS) process, demonstrate significant reductions in chip area (38.82% reduction), power consumption (52.01% reduction), and latency (25.05% improvement) compared to conventional architectures. These benefits become increasingly critical as the interleaver data length N continues to grow, providing a practical, ICD-compliant solution for resource-constrained satellite payloads and receiver designs.