• Journal of Microbiology and Biotechnology
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• v.25 no.8
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• pp.1299-1306
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• 2015

This study aims to investigate the mechanism of action of the cinnamon bark essential oil (CB), when used singly and also in combination with piperacillin, for its antimicrobial and synergistic activity against beta-lactamase TEM-1 plasmid-conferred Escherichia coli J53 R1. Viable count of bacteria for this combination of essential oil and antibiotic showed a complete killing profile at 20 h and further confirmed its synergistic effect by reducing the bacteria cell numbers. Analysis on the stability of treated cultures for cell membrane permeability by CB when tested against sodium dodecyl sulfate revealed that the bacterial cell membrane was disrupted by the essential oil. Scanning electron microscopy observation and bacterial surface charge measurement also revealed that CB causes irreversible membrane damage and reduces the bacterial surface charge. In addition, bioluminescence expression of Escherichia coli [pSB1075] and E. coli [pSB401] by CB showed reduction, indicating the possibility of the presence of quorum sensing (QS) inhibitors. Gas-chromatography and mass spectrometry of the essential oil of Cinnamomum verum showed that trans-cinnamaldehyde (72.81%), benzyl alcohol (12.5%), and eugenol (6.57%) were the major components in the essential oil. From this study, CB has the potential to reverse E. coli J53 R1 resistance to piperacillin through two pathways; modification in the permeability of the outer membrane or bacterial QS inhibition.

• Corrosion Science and Technology
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• v.20 no.6
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• pp.435-450
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• 2021

The interest in eco-friendly energy is increasing, and polymer electrolyte membrane fuel cell (PEMFC) is attracting attention as alternative power sources. Research on metallic bipolar plates, a fuel cell component, is being actively conducted. However, since the operating conditions of PEMFC, in which sulfuric acid (H₂SO₄) and hydrofluoric acid (HF) are mixed, are strong acidity, the durability of the metallic bipolar plate is very important. In this research, the electrochemical characteristics and corrosion damage behavior of 316L stainless steel, a material for metallic bipolar plates, were analyzed through potentiostatic corrosion tests with test times and chloride concentrations. As the test times and chloride concentrations increased, the current density and corrosion damage increased. As a result of observation with scanning electron microscope(SEM) and 3D microscope, both the depth and width of pitting corrosion increased with increases in test times and chloride concentrations. In particular, the pitting corrosion damage depth at test conditions of 6 hours and 1000 ppm chloride increased the most. The growth of the pitting corrosion damage was not directly proportional to time and increased significantly after a certain period.

• Journal of Microbiology and Biotechnology
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• v.12 no.2
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• pp.183-188
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• 2002

The ohmic heating of foods for sterilization provides a shorter come-up time compared to conventional thermal processes. The electric fields as well as the heat generated by ohmic heating facilitate germicidal effects. In the present study, the effect of ohmic heating on the structure and permeability of the cell membrane of yeast cells, Saccharomyces cerevisae, isolated from Takju (a traditional Korean rice-beer), was investigated. The ohmic heating was found to translocate intracellular protein materials out of the cell wall, and the amount of exuded protein increased significantly as the electric field increased from 10 to 20 V/cm. As higher frequencies were applied, more materials were exuded. Compared to conventional heating, more amounts of proteins and nucleic acids were exuded when these cells were treated with ohmic heating. The molecular weights of the major exuded proteins ranged from 14 kDa to 18 kDa, as analyzed by Tricine-SDS PAGE. A TEM study also confirmed the leakage of cellular materials, thus indicating irreversible damage to the cell wall by ohmic heating. It was, therefore, concluded that the electric fields generated by ohmic heating induced electroporation, causing irreversible damage to the yeast cell wall and promoting the translocation of intracellular materials.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.456-461
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• 2003

A fuel cell is an electrochemical device in which the energy of a chemical reaction is converted directly into electricity. By combining hydrogen fuel with oxygen from air, electricity is formed, without combustion of any form. Water and heat are the only by-products when hydrogen is used as the fuel source. Fuel cell stack consists of multi-layered unit cells. A unit cell consists of MEA and bipolar plates. The end plate of fuel cell stack should give a uniform distributed pressure to multi unit cell layers so as to reduce the contact resistance and to prevent the leakage of reactant gases and the damage of multi layer components. The current end plate is redundantly large and heavy. It makes the power per unit volume reduced. Topology optimization of end plate is conducted for mass reduction and enhancement of bending rigidity. The evaluation of the current design and the recommendation for the future design is remarked.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.1
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• pp.91-96
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• 2015

A lipopeptide extract of Bacillus amyloliquefaciens BACY1 (BLE) was found to induce cell death in human oral squamous cell carcinoma (OSCC) cell lines, SCC4 and SCC25, in this study. The results of MTT assay showed that BLE inhibited OSCC cell proliferation in a dose-dependent manner. BLE was also effective in increasing the sub-G1 phases. Furthermore, when membrane damage in SCC4 cells treated with BLE was monitored by LDH assay, release of LDH was significantly increased. The protein and mRNA levels of pro-apoptotic Bax, and caspase-3 were up-regulated by BLE. Taken together, these results suggest that BLE induces apoptosis and then inhibits the cell proliferation of human OSCC cells.

• Anatomy and Cell Biology
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• v.56 no.1
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• pp.16-24
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• 2023

Endothelial cells (EC) are the anatomical boundaries between the intravascular and extravascular space. Damage to ECs is catastrophic and induces endothelial cell dysfunction. The pathogenesis is multifactorial and involves dysregulation in the signaling pathways, membrane lipids ratio disturbance, cell-cell adhesion disturbance, unfolded protein response, lysosomal and mitochondrial stress, autophagy dysregulation, and oxidative stress. Autophagy is a lysosomal-dependent turnover of intracellular components. Autophagy was recognized early in the pathogenesis of endothelial dysfunction. Autophagy is a remarkable patho (physiological) process in the cell homeostasis regulation including EC. Regulation of autophagy rate is disease-dependent and impaired with aging. Up-regulation of autophagy induces endothelial cell regeneration/differentiation and improves the function of impaired ones. The paper scrutinizes the molecular mechanisms and triggers of EC dysregulation and current perspectives for future therapeutic strategies by autophagy targeting.

• Korean Journal of Pharmacognosy
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• v.52 no.3
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• pp.149-156
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• 2021

Excessive glutamate can cause oxidative stress in neuronal cells and this can be the reason for neurodegenerative disease. In this study, we investigated the protective effect of Spirulina maxima hot ethanol extract on mouse hippocampal HT22 cell of which glutamate receptor has no function. HT22 cells were pre-treated with S. maxima sample at a dose dependent manner (1, 10 and 100 ㎍/ml). After an hour, glutamate was treated. Cell viability, reactive oxygen species (ROS) accumulation, Ca²⁺ influx, decrease of mitochondrial membrane potential level and glutathione related assays were followed by then. S. maxima ethanol extract improved the cell viability by suppressing the ROS and Ca²⁺ formation, retaining the mitochondrial membrane potential level and protecting the activity of the antioxidant enzymes compared with group of vehicle-treated controls. These suggest that S. maxima may decelerate the neurodegeneration by attenuating neuronal damage and oxidative stress.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.28 no.1
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• pp.150-165
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• 2002

The purpose of this study was to evaluate bacteriocin activity against human flora. Lactobiocin, a bacteriocin produced by Lactococcus sp. HY 449, inhibited the growth of Starphylococcus epidermidis, Starphylococcus aureus, Streptoccoccus pyogenes and Propionibacterium acnes. When crude bacteriocin was added to indicator cells during logarithmic growth, the optical density(O.D 650nm) of cells without bacteriocin increase after 5h of incubation. Whereas in the presence of bacteriocin, the O.D of cell suspensions decreased. The similar patterns were observed for absorbance readings at 280 nm and 260 nm. The release of cellular components when cell were treated with Lactobiocin suggests some degree of membrane damage or cell lysis. Scanning electron microscopy of cells following treatments with Lactobiocin in PBS buffer revealed disruptures of cell morphology. These results indicate that bacteriocin appears to cause cell lysis of tested strains. In cytotoxicity on human fibroblast, LD$\_$50/ of Lactobiocin was ca. 50 mg/ml and no change was observed cell proliferation at the same concentration. Any irritation and allergic reaction did not observed when evaluated by human patch test for Lactobiocin.

• Biotechnology and Bioprocess Engineering:BBE
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• v.4 no.1
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• pp.59-62
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• 1999

The recombinant bacteria strain DPD2540, containing a fabA::luxCDABE fusion, was used to detect the toxicity of various chemicals in this study. Membrane damaging agents such as phenol, ethanol, and cerulenin induced a rapid bioluminescent response from this strain. Other toxic agents, such as DNA-damaging or oxidative-damaging chemicals, showed a delayed bioluminescent response in which the maximum peak appeared over 150 min after induction. This strain was also tested for measurement of toxicity in field samples such as wastewater and river water effluents.

• Journal of Cancer Prevention
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• v.21 no.2
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• pp.95-103
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• 2016

Background: Excess energy supply induces chronic low-grade inflammation in association with oxidative stress in various tissues including intestinal epithelium. The objective of this study was to investigate the effect of high-fat diet (HFD) on intestinal cell membrane integrity and intestinal tumorigenesis in $Apc^{Min/+}$ mice. Methods: Mice were fed with either normal diet (ND) or HFD for 12 weeks. The number of intestinal tumors were counted and biomarkers of endotoxemia, oxidative stress, and inflammation were determined. Changes in intestinal integrity was measured by fluorescein isothiocyanate (FITC)-dextran penetration and membrane gap junction protein expression. Results: HFD group had significantly higher number of tumors compared to ND group (P < 0.05). Blood total antioxidant capacity was lower in HFD group, while colonic 8-hydroxy-2'-deoxyguanosine level, a marker of oxidative damage, was higher in HFD group compared to that of ND group (P < 0.05). The penetration of FITC-dextran was substantially increased in HFD group (P < 0.05) while the expressions of membrane gap junction proteins including zonula occludens-1, claudin-1, and occludin were lower in HFD group (P < 0.05) compared to those in ND group. Serum concentration of lipopolysaccharide (LPS) receptor (CD14) and colonic toll-like receptor 4 (a LPS receptor) mRNA expression were significantly higher in HFD group than in ND group (P < 0.05), suggesting that significant endotoxemia may occur in HFD group due to the increased membrane permeability. Serum interleukin-6 concentration and myeloperoxidase activity were also higher in HFD group compared to those of ND group (P < 0.05). Conclusions: HFD increases oxidative stress disrupting intestinal gap junction proteins, thereby accelerating membrane permeability endotoxemia, inflammation, and intestinal tumorigenesis.