• Journal of Microbiology and Biotechnology
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• v.21 no.9
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• pp.979-987
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• 2011

Culture pH change has some important roles in signal transduction and secondary metabolism. We have already reported that acidic pH shock enhanced actinorhodin production in Streptomyces coelicolor. Among many potential governing factors on pH variation, the putative $Na^+/H^+$ antiporter (sha) genes in S. coelicolor have been investigated in this study to elucidate the association of the sha on pH variation and secondary metabolism. Through the transcriptional analysis and overexpression experiments on 8 sha genes, we observed that most of the sha expressions were promoted by pH shock, and in the opposite way the pH changes and actinorhodin production were enhanced by the overexpression of each sha. We also confirmed that sha8 especially has a main role in maintaining cell viability and pH homeostasis through $Na^+$ extrusion, in salt effect experiment under the alkaline medium condition by deleting sha8. Moreover, this gene was observed to have a function of pH recovery after pH variation such as the pH shock, being able to cause the sporulation. However, actinorhodin production was not induced by the only pH recovery. The sha8 gene could confer on the host cell the ability to recover pH to the neutral level after pH variation like a pH drop. Sporulation was closely associated with this pH recovery caused by the action of sha8, whereas actinorhodin production was not due to such pH variation patterns alone.

• Journal of Sensor Science and Technology
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• v.17 no.4
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• pp.245-249
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• 2008

This paper presents a microfluidic cell sizing method using hydrophoretic size-based separation. By exploiting slanted obstacles in a microchannel, we can generate a lateral pressure gradient so that microparticles can be deflected and arranged along lateral flows induced by the gradient. Using such movement of particles, we discriminated 8 to 15 μm-sized beads. We measured the size of U937 cells by comparing the hydrophoretic response of the cells to those of the size-standard beads whose diameters are known. Due to its simple design and fabrication, the sizing method can be easily integrated with other microfluidic components such as cell culture chambers conducting on-chip sizing and sorting.

• Toxicological Research
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• v.14 no.4
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• pp.541-545
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• 1998

This experiment carried out to compare the protective effects of some antioxidants to hydroxyl radicals in embryonic mouse whole brain tissue culture. The ICR mouse whole brain (13 embryonic day) was cultured in hydroxyl radical system in which radicals were generated by 20 mU / ml glucose oxidase (GO). In this experiment, to make ferrous iron from ferric iron, iron as an accelerator, and ascorbic acid as a reductant were used. For comparison of the protective effects to hydroxyl radicals, antioxidants such as desferrioxamine (DFX), laccase. water or ethanol extracts from Rhus Vemiciflua Stokes (RVS), and $\alpha$-tocopherol were used, because they relate to metal ion. The results of this experiment showed that all antioxidants protected effectively the cytotoxicity from hydroxyl radicals in the brain cultures. More than 70% of cell viabilities among different antioxidants was at 1 mM DFX, 1.43 $\mu\textrm{m}$ laccase, 12.5 $\mu\textrm{m}$ water extract, 12.5 $\mu\textrm{m}$ ethanol extract and 50 $\mu\textrm{m}$ $\alpha$-tocopherol individually, compared with 20 mU/ml GO alone. In comparison to the antioxidative activities of antioxidants, laccase and extracts from RVS showed strong antioxidative effects even at low concentration.

• Preventive Nutrition and Food Science
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• v.15 no.4
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• pp.255-261
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• 2010

Ischemic stroke, a major cause of death and disability worldwide, is caused by occlusion of cerebral arteries that, coupled with or without reperfusion, results in prolonged ischemia (hypoxia and hypoglycemia) and, ultimately, brain damage. In this study, we examined whether methanol extract of the whole plant of Cassia mimosoides var. nomame Makino that grows naturally in Korea, as well as Japan and China, and some of its fractions obtained by partitioning with organic solvents could protect human hepatocellular carcinoma cells (HepG2) under hypoxic condition by inhibiting apoptosis. We also investigated if these extracts could attenuate brain damage in a rat model of 2 hr of ischemia, generated by middle cerebral artery occlusion, and 22 hr of reperfusion. The whole extract ($100{\mu}g$/mL) maintained the cell number at more than half of that initially plated, even after 24 hr of cell culture under hypoxic condition (3% $O_2$). In the absence of the whole extract, almost all of the cells were dead by this time point. This improvement of cell viability came from a delay of apoptosis, which was confirmed by observing the timing of the formation of a DNA ladder when assessed by gel electrophoresis. Of fractions soluble in hexane, ethyl acetate (EA), butanol and water, EA extracts were selected for the animal experiments, as they improved cell viability at the lowest concentration ($10{\mu}g$/mL). The whole extract (200 mg/kg) and EA extract (10 and 20 mg/kg) significantly reduced infarct size, a measure of brain damage, by 34.7, 33.8 and 45.2.0%, respectively, when assessed by 2,3,5-triphenyl tetrazolium chloride staining. The results suggest that intake of Cassia mimosoides var. nomame Makino might be beneficial for preventing ischemic stroke through inhibition of brain cell apoptosis.

• YAKHAK HOEJI
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• v.24 no.3_4
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• pp.143-150
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• 1980

The effect of ginseng saponin on chick embryonic dorsal root ganglia organ culture and brain, spinal cord, muscle dissociation cultures was studied. The fiber outgrowth in explanted chick embryonic dorsal root ganglia was markedly induced by water and alcohol extracts of ginseng, total ginseng saponin, protopanaxadiol and protopanaxatriol glycosides as well as ginsenosides R/sub b1/, R/sub d/, R/sub 0/+R/sub a/+R/sub b1/, and R/sub b2/+R/sub c/+R/sub e/ mixtures. The life span of the cultured chick embryonic dorsal root ganglia and potentiation of nerve cell density were also observed with all of these ginseng saponins. The effect of ginseng saponin on chick embryonic dorsal root ganglia organ culture was more marked in the absence of the chick embryonic extract which was known to contain nerve growth factor-like material in the culture media. However, the ginseng saponin did not influence the cultured central nervous system such as brain and spinal cord cells and cultured skeletal muscle cells with respect to the morphological changes, maturation and life span of these cells.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.11
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• pp.1127-1131
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• 2011

We report on a pumpless cell culture chip in which a constant medium perfusion rate is maintained by balanced droplet dispensing. Previous chips had a decreasing perfusion rate due to the decreasing hydraulic-head difference ${\Delta}h$ between the inlet and drain. However, the present chip maintains a constant medium perfusion rate due to the constant ${\Delta}h$ between the inlet and drain maintained by balanced droplet dispensing. The perfusion rate Q was measured to be 0.1-$0.3{\mu}l$/min with a maximum deviation and error of 9.96% and 6.92%, respectively. In the perfusion culture (Q = 0.1-$0.3{\mu}l$/min), the maximum growth-rate of H358 cells was measured to be $57.8%{\pm}21.1%$ per day, which is 1.9 times higher than that of a static culture. The perfusion culture also resulted in higher cell viability than a static culture. The present chip offers a favorable environment with a high growth-rate and viability and thus has potential for use in the integrated cell culture system.

• BMB Reports
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• v.57 no.7
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• pp.311-317
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• 2024

Brain organoid is a three-dimensional (3D) tissue derived from stem cells such as induced pluripotent stem cells (iPSCs) embryonic stem cells (ESCs) that reflect real human brain structure. It replicates the complexity and development of the human brain, enabling studies of the human brain in vitro. With emerging technologies, its application is various, including disease modeling and drug screening. A variety of experimental methods have been used to study structural and molecular characteristics of brain organoids. However, electrophysiological analysis is necessary to understand their functional characteristics and complexity. Although electrophysiological approaches have rapidly advanced for monolayered cells, there are some limitations in studying electrophysiological and neural network characteristics due to the lack of 3D characteristics. Herein, electrophysiological measurement and analytical methods related to neural complexity and 3D characteristics of brain organoids are reviewed. Overall, electrophysiological understanding of brain organoids allows us to overcome limitations of monolayer in vitro cell culture models, providing deep insights into the neural network complex of the real human brain and new ways of disease modeling.

• The Journal of Internal Korean Medicine
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• v.29 no.1
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• pp.231-242
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• 2008

Objectives : We can find out the experimental reports of Yanggyuksanhwa-tang, which has the function of regulating blood pressure related with cerebral disease, and increasing local cerebral blood stream volume, also has the recoveries for the damage of vessel endothelium, and endothelium hypertrophy caused by angiospasm after subarachnoid hemorrhage, and reduces the contraction of smooth muscle, so simultaneously improves necrosis. The aim of this study is to investigate effect of Yanggyuksanhwa-tang protecting neuronal cells from being damaged by brain ischemia through using organotypic hippocampal slice cultures. Methods : We caused ischemic damage to organotypic hippocampal slice cultures by oxygen and glucose deprivation, and Yanggyuksanhwa-tang extract was added to cultures. Thereafter we measured area percentage of propidium iodide (PI)-stained neuronal cell, lactate dehydrogenase (LDH) levels in culture media and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL)-positive cells. Results : Area percentage of PI-stained neuronal cells and count of TUNEL-positive cells in CA1 and DG area of organotypic hippocampal slice culture were significantly decreased in pertinent density level of Yanggyuksanhwa-tang extract. LDH levels in culture media of organotypic hippocampal slice culture were significantly decreased in pertinent density level of Yanggyuksanhwa-tang extract. Conclusions : Within pertinent density level, Yanggyuksanhwa-tang has cell protection effect that prevents brain ischemia damaging neuronal cells and apoptosis increasing.

• Journal of Korean Neurosurgical Society
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• v.42 no.2
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• pp.118-124
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• 2007

Objective : Adipose tissue is derived from the embryonic mesoderm and contains a heterogenous stromal cell population. Authors have tried to verify the characteristics of stem cell of adipose derived stromal cells (ADSCs) and to investigate immunohistochemical findings after transplantation of ADSC into rat brain to evaluate survival, migration and differentiation of transplanted stromal cells. Methods : First ADSCs were isolated from human adipose tissue and induced adipose, osseous and neuronal differentiation under appropriate culture condition in vitro and examined phenotypes profile of human ADSCs in undifferentiated states using flow cytometry and immunohistochemical study. Human ADSCs were transplanted into the healthy rat brain to investigate survival, migration and differentiation after 4 weeks. Results : From human adipose tissue, adipose stem cells were harvested and subcultured for several times. The cultured ADSCs were differentiated into adipocytes, osteoctye and neuron-like cell under conditioned media. Flow cytometric analysis of undifferentiated ADSCs revealed that ADSCs were positive for CD29, CD44 and negative for CD34, CD45, CD117 and HLA-DR. Transplanted human ADSCs were found mainly in cortex adjacent to injection site and migrated from injection site at a distance of at least 1 mm along the cortex and corpus callosum. A few transplanted cells have differentiated into neuron and astrocyte. Conclusion : ADSCs were differentiated into multilineage cell lines through transdifferentiation. ADSCs were survived and migrated in xenograft without immunosuppression. Based on this data, ADSCs may be potential source of stem cells for many human disease including neurologic disorder.

• Journal of the Korean institute of surface engineering
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• v.41 no.2
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• pp.69-75
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• 2008

Electrochemical behaviors of surface modified and MC3T3-E1 cell cultured Ti-30Ta alloys have been investigated using various electrochemical methods. The Ti alloys containing Ta were melted by using a vacuum furnace and then homogenized for 6 hrs at $1000^{\circ}C$. MC3T3-E1 cell culture was performed with MC3T3-E1 mouse osteoblasts for 2 days. The microstructures and corrosion resistance were measured using FE-SEM, XRD, EIS and potentiodynamic test in artificial saliva solution at $36.5{\pm}1^{\circ}C$. Ti-Ta alloy showed the martensite structure of ${\alpha}+{\beta}$ phase and micro-structure was changed from lamellar structure to needle-like structure as Ta content increased. Corrosion resistance increased as Ta content increased. Corrosion resistance of cell cultured Ti-Ta alloy increased predominantly in compared with non cell cultured Ti- Ta alloy due to inhibition of the dissolution of metal ion by covered cell. $R_p$ value of MC3T3-E1 cell cultured Ti-40 Ta alloy showed $1.60{\times}10^6{\Omega}cm^2$ which was higher than those of other Ti alloy. Polarization resistance of cell-cultured Ti-Ta alloy increased in compared with non-cell cultured Ti alloy.