• BMB Reports
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• v.32 no.5
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• pp.440-444
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• 1999

Membrane lipid peroxidation processes yield reactive aldehydes that may react with copper,zinc superoxide dismutase (Cu,Zn SOD), one of the key antioxidant enzymes against oxidative stress. We investigated this possibility and found that exposing Cu,Zn SOD to malondialdehyde (MDA) or 4-hydroxynonenal (HNE) caused the loss of dismutase activity, cross-linking of peptides, and an increase in protein oxidation, reflected by the increased level of carbonyl groups. When Cu,Zn SOD that had been exposed to MDA or HNE was subsequently analyzed by amino acid analysis, histidine content was found to be significantly lost. Both MDA-and HNE-treated Cu,Zn SOD were resistant to proteolysis, which may imply that damaged proteins exist in vivo for a longer period of time than the native enzyme. The lipid peroxidation-mediated damage to Cu,Zn SOD may result in the perturbation of cellular antioxidant defense mechanisms, and subsequently lead to a pro-oxidant condition.

• Food Science and Biotechnology
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• v.14 no.2
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• pp.286-289
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• 2005

Active antibacterial compound against periodontitis-causing bacterium Porphyromonas gingivalis was isolated from Kaempferia pandurata and identified as panduratin A. Minimum inhibitory concentration (MIC) value of panduratin A was $4\;{\mu}g/mL$, much lower than those of other natural antibacterial agents. Panduratin A also showed antibacterial activity against Prevotella intermedia ($2\;{\mu}g/mL$), P. loescheii ($4\;{\mu}g/mL$), and cariogenic Streptococcus mutans ($4\;{\mu}g/mL$). Damage on cell wall and perturbation of cytoplasmic membrane of panduratin A-treated P. gingivalis were visualized through transmission electron microscopy. These results suggest panduratin A, exhibiting strong and preferential antiperiodontal and anticariogenic activities, may be utilized in functional foods for prevention of oral diseases.

• Proceedings of the KIEE Conference
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• 1995.11a
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• pp.154-156
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• 1995

The effect of a periodic and a chaotic' behaviour in the Bonhoeffer-Van der Pol(BVP) oscillation of the nerve membrane driven by a periodic stimulating current $A_1=cos\;{\omega}\;t$ are investigated by numeric analysis and hardware Implementation. To control the chaotic motion, we are suggested by temperature parameter c, $c=c(1+\eta\;cos\;{\Omega}\;t)$ which the values of $\eta,\;Omega$ varied respectively. The feasibilities of chaotic and periodic phenomena were analysed by phase plane and time series.

• Journal of the Korean Society of Food Science and Nutrition
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• v.26 no.6
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• pp.1258-1267
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• 1997

Corbon dioxide id effective for extending the shelf-life of perishable foods by retarding microbial growth. The overall effect of carbon dioxide is to increase both the lag phase and generation time of microorganisms. However, the role of carbon dioxide in affecting the growth and metabolism of any given microorganisms is not clear yet, although its inhibitory effect is generally found at moderate to high concentrations. Systematic studies of the effects of carbon dioxide on microorganisms are therefore warranted. It is also necessary to understand the role of carbon dioxide in the preservation of foods as well as the control by carbon dioxide of fermentations of biotechnological importance. In this review, the antimicrobial effect of carbon dioxide on microorganisms is investigated in terms of its gas and solution properties, inhibition of microbial growth and specific metabolic processes, perturbation of membrane structure.

• The Korean Journal of Pharmacology
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• v.24 no.1
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• pp.43-52
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• 1988

To elucidate the mechanism of action of local anesthetics, the effects of local anethetics on the microenvironment of the lipid bilayers of synaptosomal plasma membrane vesicles (SPMV) isolated from bovine brain and dimyristoylphosphatidylcholine (DMPC) multilamellar liposomes were investigated employing the intermolecular excimer fluorescence technique and differential scanning calorimetry (DSC). The relative intensities of excimer and monomer fluorescence of pyrene are a simple linear function of the viscosity of a homologous series of solvents. The microviscosity(${\eta}$)of the hydrocarbon region of SPMV was measured by this method and the value was $57.3{\pm}5.3\;cP$ at $37^{\circ}C$. In the presence of lidocaine-HCl and procaine-HCl, the values decreased to $46.5{\pm}5.1\;cP$ and $54.7{\pm}4.8\;cP$, respectvely. The differential scanning thermograms of DMPC multilamellar liposomes showed that local anesthetics significantly lowered the phase transition temperature, broadened the thermogram peaks, and reduced the size of the cooperative unit. These results indicate that local anesthetics have significant fluidizing effects on biomembranes and perturbation of membrane lipids may produce some, but not all, of their pharmacological actions.

• Journal of the Optical Society of Korea
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• v.20 no.1
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• pp.78-87
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• 2016

Red blood cells (RBCs) are customarily adhered to a bio-functionalised substrate to make them stationary in interferometric phase-imaging modalities. This can make them susceptible to receive alterations in innate morphology due to their own weight. Optical tweezers (OTs) often driven by Gaussian profile of a laser beam is an alternative modality to overcome contact-induced perturbation but at the same time a steeply focused laser beam might cause photo-damage. In order to address both the photo-damage and substrate adherence induced perturbations, we were motivated to stabilize the RBC in OTs by utilizing a laser beam of ‘arbitrary intensity profile’ generated by a source having cavity imperfections per se. Thus the immobilized RBC was investigated for phase-imaging with sinusoidal interferograms generated by a compact and robust Michelson interferometer which was designed from a cubic beam splitter having one surface coated with reflective material and another adjacent coplanar surface aligned against a mirror. Reflected interferograms from bilayers membrane of a trapped RBC were recorded and analyzed. Our phase-imaging set-up is limited to work in reflection configuration only because of the availability of an upright microscope. Due to RBC’s membrane being poorly reflective for visible wavelengths, quantitative information in the signal is weak and therefore, the quality of experimental results is limited in comparison to results obtained in transmission mode by various holographic techniques reported elsewhere.

• Journal of Physiology & Pathology in Korean Medicine
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• v.20 no.6
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• pp.1516-1523
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• 2006

The water extract of Danchunhwan(DCH) has been traditionally used for treatment of dementia damage in oriental medicine. However, little is known about the mechanism by which the water extract of DCH rescues cells from neurodegenerative disease such as Alzheimer's disease. This study was designed to investigate the protective mechanisms of DCH on ${\beta}$-amyloid or $H_2O_2$-induced cytotoxicity in SH-SY5Y neuronblastoma cells. ${\beta}$-amyloid and $H_2O_2$ markedly decreased the viability of SH-SY5Y cells, which was characterized with apparent apoptotic features such as membrane blebbing as well as fragmentation of genomic DNA and nuclei. However, the water extract of DCH significantly reduced both ${\beta}$-amyloid or $H_2O_2$-induced cell death and apoptotic characteristics through reduction of intracellular peroxide generation. Also, the water extract of DCH prevented prevented the mitochondrial dysfunction including the disruption of mitochondria membrane permeability transition (MPT) and the perturbation in Bcl-2 family protein expressions in $H_2O_2$-treated SH-SY5Y cells.

• Journal of Microbiology and Biotechnology
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• v.28 no.3
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• pp.381-390
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• 2018

We have previously derived a novel antimicrobial peptide, LPcin-YK3(YK3), based on lactophoricin and have successfully studied and reported on the relationship between its structure and function. In this study, antimicrobial peptides with improved antimicrobial activity, less cytotoxicity, and shorter length were devised and characterized on the basis of YK3, and named YK5, YK8, and YK11. The peptide design was based on a variety of knowledge, and a total of nine analog peptides consisted of one to three amino acid substitutions and C-terminal deletions. In detail, tryptophan substitution improved the membrane perturbation, lysine substitution increased the net charge, and excessive amphipathicity decreased. The analog peptides were examined for structural characteristics through spectroscopic analytical techniques, and antimicrobial susceptibility tests were used to confirm their activity and safety. We expect that these studies will provide a platform for systematic engineering of new antibiotic peptides and generate libraries of various antibiotic peptides.

• Food Science and Preservation
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• v.16 no.3
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• pp.392-399
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• 2009

Recent studies indicate that green tea may have anticancer, antioxidant, and antihypertensive effects, and aids body weight control and the promotion of various desirable physiological functions. However, few studies have investigated the antimicrobial effects of green tea. We sought to determine the antimicrobial activity of green tea extract against food spoilage microorganisms. The extract showed remarkable antimicrobial effects against a wide spectrum of putrefactive and food spoilage microorganisms when used at concentrations greater than $500{\mu}g/ml$. The extract showed thermal and pH stability in the range of $40{\sim}150^{\circ}C$ and pH 3.11, respectively. Green tea extract seems to be an ideal natural antimicrobial, considering both efficacy and thermal and pH stabilities. Antimicrobial substances in green tea extract were investigated using electron microscopy and a $\beta$-galactosidase assay. The data showed that the extract contains several efficacious materials, and that their activities are not synergistic but are instead independent. Our data indicate that hydrophilic antimicrobial substances in green tea extract might control food spoilage microorganisms owing to perturbation of the microbial cell membrane.

• Korean Journal of Clinical Laboratory Science
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• v.45 no.3
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• pp.114-119
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• 2013

Potassium is essential for the proper functioning of the ears. The inner ear's endolymph differs from all other extracellular fluids (in its positive potential) and in the ionic compositions in the various parts of the endolymphatic space. Ion concentration of the endolymph is 150 mM of potassium, which is comparable to the concentrations in other organs. Cisplatin (cis-diamminedichloroplatinum II: CDDP) is one of the most effective anticancer drugs, widely used against various tumors. However, its clinical use is limited by the onset of severe side effects, including ototoxicity and nephrotoxicity. For ototoxicity, a number of evidences in cytotoxic mechanism of cisplatin, including perturbation of redox status, increase in lipid peroxydation, and formation of DNA adduct, have been suggested. Therefore, in this study, the author investigated the relationship between the potassium ions on cisplatin-induced cytotoxicity in HEI-OC1 cells associated with reactive oxygen species (ROS). KCNE1 gene expression by the concentration of intracellular potassium appeared in the plasma membrane and increased the concentration of intracellular potassium. Cisplatin decreased the viability of HEI-OC1 cells, but the KCNE1 gene increased. Also, the KCNE1 gene significantly suppressed generation of intracellular ROS by cisplatin. Western blot analysis showed that the KCNE1 gene increased phase II detoxification enzymes markers such as superoxide dismutase 1 (SOD1), superoxide dismutase (SOD2), NAD(P)H:quinine oxidoreductases (NQO1), which were associated with the scavenger of ROS. These results suggest that the KCNE1 gene for intracellular potassium concentration ultimately prevents ROS generation from cisplatin and further contributes to protect auditory sensory hair cells from ROS produced by cisplatin.