• The Korean Journal of Physiology
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• 제27권2호
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• pp.123-138
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• 1993

The mechanism of insulin action to increase glucose transport is attributed to glucose transporter translocation from intracellular storage pools to the plasma membrane in insulin-sensitive cells. The present study was designed to visualize the redistribution of the glucose transporter by means of an immunogold labelling method. Our data clearly show that glucose transporter molecules were visible by this method. According to the method this distribution of glucose transporters between cell surface and intracellular pool was different in adipocytes. The glucose transporter molecules were randomly distributed at the cell surface whereas the molecules at LDM were farmed as clusters. By insulin treatment the number of homogeneous random particles increased at the cell surface whereas the cluster forms decreased at the intracellular storage pools. It suggests that the active molecules needed to be evenly distributed far effective function and that the inactive molecules in storage pools gathered and termed clusters until being transferred to the plasma membrane.

• 상하수도학회지
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• 제21권3호
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• pp.349-357
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• 2007

Reports of endocrine disrupting compounds (EDCs), pharmaceutically active compounds (PhACs), and personal care products (PCPs) have raised substantial concern in important potable drinking water quality issues. Our study investigates the removal of EDCs, PhACs, and PCPs of 10 compounds having different physico-chemical properties (e.g., molecular weight, and octanol-water partition coefficient ($K_{OW}$)) by nanofiltration (NF) membranes. The rejection of micropollutants by NF membranes ranged from 93.9% to 99.9% depending on solute characteristics. A batch adsorption experiments indicated that adsorption is an important mechanism for transport/removal of relatively hydrophobic compounds, and is related to the octanol-water partition coefficient values. The transport phenomenon associated with adsorption may also depend on solution water chemistry such as pH and ionic strength influencing the pKa value of compounds. In addition, it was visually seen that the retention was somewhat higher for the larger compounds based on their molecular weight. These results suggest that the NF membrane retains many organic compounds due to both hydrophobic adsorption and size exclusion mechanisms.

• Journal of Ginseng Research
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• 제14권2호
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• pp.135-141
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• 1990

In order to elucidate the mechanism of the leaf-burning disease of ginseng (Panax ginseng C.A. Meyer), the relationships between thylakoid membrane peroxidation and chlorophyll bleaching were investigated in comparison with the ones of soybean (Glycine max L). When I measured the rate of lipid peroxidation in the thylakoids of ginseng and soybean by irradiation of light(60 w.m-2), it was identified that, the remarkably lower rate of lipid peroxidation was found in the ginseng thylakoid than the case of soybean. When lipid peroxidation of ginseng thylakoid was induced in the dark, chlorophyll contents of thylakoid was not changed. The results suggest that lipid peroxidation does not affect the chlorophyll bleaching in ginseng thylakoid. Thylakoid membrane peroxidation as well as chlorophyll bleaching was closely related with photosynthetic electron transport. But, according to the quenching experiment active oxygen species induced lipid peroxidation may be different species in the case of chlorophyll bleaching.

• BMB Reports
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• 제33권6호
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• pp.427-439
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• 2000

The activity of the phagocyte respiratory burst oxidase is regulated by complex and dynamic alterations in protein-protein interactions that result in the rapid assembly of an active multicomponent NADPH oxidase enzyme on the plasma membrane. While the enzymatic activity has been studied for the past 20 years, the past decade has seen remarkable progress in our understanding of the enzyme and its activation at the molecular level. This article describes the current state of knowledge, and proposes a model for the mechanism by which protein-protein interactions regulate enzyme activity in this system.

• Journal of Ginseng Research
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• 제30권2호
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• pp.70-77
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• 2006

Ginseng has an anti-cancer effect in several cancer models. As a mechanism study of ginsenoside-induced growth inhibition in cancer cells, we measured change of membrane potential in prostate cancer and glioma cells by ginsenosides, active constituents of ginseng. Membrane potential was estimated by measuring fluorescence change of DiBAC-Ioaded cells. Among 11 ginsenosides tested, ginsenosides $Rb_2$, $Rg_3$, and $Rh_2$ increased significantly and robustly the membrane potential in a concentration-dependent manner in prostate cancer and glioma cells. Ginsenosides Rc, Ro, and $Rb_1$ slightly increased membrane potential. The ginsenoside-induced membrane potential increase was not affected by treatment with pertussis toxin or U73122. The ginsenoside-induced membrane potential increase was not diminished in $Na^+$-free or $HCO_3^-$-free media. Furthermore, the ginsenoside-induced increase of membrane potential was not changed by EIPA (5-(N-ethyl-N-isopropyl)-amiloride), SITS (4-acetoamido-4'-isothiocyanostilbene-2,2'-disulfonic acid), and omeprazole. In summary, ginsenosides $Rb_2$, $Rg_3$, and $Rh_2$ increased membrane potential in prostate cancer and glioma cells in a GPCR-independent and $Na^+$ independent manner.

• 한국수소및신에너지학회논문집
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• 제20권4호
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• pp.317-322
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• 2009

To investigate degradation mechanism of PEMFC operated with repetitive startup/shutdown cycling, i-V characteristics, impedance, cyclic voltamograms were measured. OCV decreased from 0.967 to 0.951 V while the cell voltage at 800mA/$cm^2$ from 0.657 to 0.563V, implying that the electrodes rather than membrane electrolyte was damaged during the cycling operation. Electrochemical analyses supported that the performance degradation could be mainly attributed to degradation of the electrodes such as a decrease in electrochemical active surface area rather than degradation of membrane.

• Biomolecules & Therapeutics
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• 제27권3호
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• pp.276-282
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• 2019

${\beta}$-amyloid precursor protein (APP) can be cleaved by ${\alpha}$-, and ${\gamma}$-secretase at plasma membrane producing soluble ectodomain fragment ($sAPP{\alpha}$). Alternatively, following endocytosis, APP is cleaved by ${\beta}$-, and ${\gamma}$-secretase at early endosomes generating ${\beta}$-amyloid ($A{\beta}$), the main culprit in Alzheimer's disease (AD). Thus, APP endocytosis is critical for $A{\beta}$ production. Recently, we reported that Monsonia angustifolia, the indigenous vegetables consumed in Tanzania, improved cognitive function and decreased $A{\beta}$ production. In this study, we examined the underlying mechanism of justicidin A, the active compound of M. angustifolia, on $A{\beta}$ production. We found that justicidin A reduced endocytosis of APP, increasing $sAPP{\alpha}$ level, while decreasing $A{\beta}$ level in HeLa cells overexpressing human APP with the Swedish mutation. The effect of justicidin A on $A{\beta}$ production was blocked by endocytosis inhibitors, indicating that the decreased APP endocytosis by justicidin A is the underlying mechanism. Thus, justicidin A, the active compound of M. angustifolia, may be a novel agent for AD treatment.

• Journal of Microbiology and Biotechnology
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• 제19권12호
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• pp.1635-1643
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• 2009

The aim of this study was to provide new insight into the mechanism whereby the housekeeping enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) locates to cell walls of Lactobacillus plantarum 299v. After purification, cytosolic and cell wall GAPDH (cw-GAPDH) forms were characterized and shown to be identical homotetrameric active enzymes. GAPDH concentration on cell walls was growth-time dependent. Free GAPDH was not observed on the culture supernatant at any time during growth, and provoked cell lysis was not concomitant with any reassociation of GAPDH onto the cell surface. Hence, with the possibility of cw-GAPDH resulting from autolysis being unlikely, entrapment of intracellular GAPDH on the cell wall after a passive efflux through altered plasma membrane was investigated. Flow cytometry was used to assess L. plantarum 299v membrane permeabilization after labeling with propidium iodide (PI). By combining PI uptake and cw-GAPDH activity measurements, we demonstrate here that the increase in cw-GAPDH concentration from the early exponential phase to the late stationary phase is closely related to an increase in plasma membrane permeability during growth. Moreover, we observed that increases in both plasma membrane permeability and cw-GAPDH activity were delayed when glucose was added during L. plantarum 299v growth. Using a double labeling of L. plantarum 299v cells with anti-GAPDH antibodies and propidium iodide, we established unambiguously that cells with impaired membrane manifest five times more cw-GAPDH than unaltered cells. Our results show that plasma membrane permeability appears to be closely related to the efflux of GAPDH on the bacterial cell surface, offering new insight into the understanding of the cell wall location of this enzyme.

• 로봇학회논문지
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• 제4권1호
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• pp.34-42
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• 2009

Rodents, specially rats, can recognize distance and shape of an object and also pattern of the textures by using their whiskers. Mechanoreceptors surrounding the root of whisker in their follicle measure deflection of the whisker. Rats can move their whisker back and forth freely. This ability, called active whisking or active sensing, is one of characteristics of rat behaviours. Many researches based on the mechanism have been progressed. In this paper, we test a simple and accurate method based on deflection of the whisker: we designed biomimetic whiskers modeling after a structure of follicle using the microphone. The microphone sensor measures a mechanical vibration. Attaching an artificial whisker beam to the microphone membrane, we can detect a vibration of whisker and this can show the deflection amount of whisker indirectly.

• The Korean Journal of Physiology
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• 제30권2호
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• pp.279-288
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• 1996

Chronic exposure to cadmium impairs various renal tubular functions, including organic acid (anion) secretion. To investigate the mechanism of cadmium-induced alterations in the organic anion transport system, kinetics of p-aminohippurate (PAH) uptake was studied in renal cortical basolateral membrane vesicles (BLMV) isolated from cadmium-intoxicated rats (adult male Sprague-Dawley). Cadmium intoxication was induced by subcutaneous injections of $CdCl_{2}$ (2 mg Cd/kg per day) for 3 weeks. The renal plasma membrane vesicles were prepared by Percoll gradient centrifugation. The vesicular uptake of $^{14}C$-PAH was determined by rapid filtration technique using Millipore filter. Cadmium intoxication resulted in a marked attenuation of $Na^{+}$-dependent, ${\alpha}$-ketoglutarate (${\alpha}$KG)-driven PAH uptake with no changes in $Na^{+}$ and ${\alpha}$KG-independent transport component. Kinetic analysis indicated that Vmax, but not Km, of the $Na^{+}$-dependent, ${\alpha}$KG-driven component was reduced. A similar reduction of $Na^{+}$-dependent, ${\alpha}$KG-driven PAH uptake was observed in normal membrane vesicles directly exposed to inorganic cadmium in vitro, and this was accompanied by an inhibition of both $Na^{+}$-dependent ${\alpha}$KG uptake and ${\alpha}$KG-PAH exchange activity. These results indicate that during chronic exposure to cadmium, free cadmium ions liberated in the proximal tubular cytoplasm directly interact with the basolateral membrane and impair the active transport capacity for organic anions, most likely due to an inhibition of both $Na^{+}$-dicarboxylate cotransporter and dicarboxylate-organic anion antiporter activities.