• The Microorganisms and Industry
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• v.14 no.3
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• pp.3-6
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• 1988

본고에서는 kem1 유전자의 기능에 대해 중점적으로 연구한 결과를 서술하려 한다.

• Journal of Biomedical Engineering Research
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• v.15 no.1
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• pp.1-8
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• 1994

Electrofusion of cabbage protoplasts was performed with a developed equipment which consists of a parallel wire electrode, a AC field generator, and a pulse generator. Exposure of protoplasts to an alternating current field of 450 KHz causes attraction to each other which leads to chains of protoplasts extending from the electrode. Intra-specific protoplast fusion was effectively induced within the pearl chains by the additional application of a single high-intensity DC square wave pulse of 1 KV/cm for 1-3 msec. To improve the performance, micro fusion electrode fabricated from the semiconductor technology and microcontroller based field an, d pulse generator was proposed. The viability of protoplasts after an application of electric field at optimum condition was reduced by only 5 % compared with that of pre-application. A prototype of fusion electrode, which consists of insulator-structure, was successfully fabricated by using photosensitive polyimide.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.327-329
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• 2008

We have studied the optically compensated splay (OCS) mode using reactive mesogen monomer to reduce critical voltage, setting voltage and phase transition time from initial bend to splay state. The high pretilt angle from vertical alignment was formed through the polymerization of UV curable RM monomer at the surfaces. In this way, orientation of the LC with OCS can be achieved without setting voltage.

• Journal of Microbiology and Biotechnology
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• v.25 no.2
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• pp.274-279
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• 2015

Receptor activator of nuclear factor-kappa B ligand (RANKL) is a critical factor in osteoclastogenesis. It makes osteoclasts differentiate and multinucleate in bone remodeling. In the present study, RANKL was expressed as a soluble maltose binding protein (MBP)-fusion protein using the Escherichia coli maltose binding domain tag system (pMAL) expression vector system. The host cell E. coli DH5α was cultured and induced by isopropyl β-_D-1-thiogalactopyranoside for rRANKL expression. Cells were disrupted by sonication to collect soluble MBP-fused rRANKL. The MBP-fusion rRANKL was purified with MBP Trap affinity chromatography and treated with Tobacco Etch Virus nuclear inclusion endopeptidase (TEV protease) to remove the MBP fusion protein. Dialysis was then carried out to remove binding maltose from the cleaved rRANKL solution. The cleaved rRANKL was purified with a second MBP Trap affinity chromatography to separate unsevered MBP-fusion rRANKL and cleaved MBP fusion protein. The purified rRANKL was shown to have biological activity by performing in vitro cell tests. In conclusion, biologically active rRANKL was successfully purified by a simple two-step chromatography purification process with one column.

• Biomolecules & Therapeutics
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• v.28 no.4
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• pp.311-319
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• 2020

Middle East Respiratory Syndrome Coronavirus (MERS-CoV) is a newly emerging viral disease with fatal outcomes. However, no MERS-CoV-specific treatment is commercially available. Given the absence of previous structure-based drug discovery studies targeting MERS-CoV fusion proteins, this set of compounds is considered the first generation of MERS-CoV small molecule fusion inhibitors. After a virtual screening campaign of 1.56 million compounds followed by cell-cell fusion assay and MERS-CoV plaques inhibition assay, three new compounds were identified. Compound numbers 22, 73, and 74 showed IC₅₀ values of 12.6, 21.8, and 11.12 µM, respectively, and were most effective at the onset of spike-receptor interactions. The compounds exhibited safe profiles against Human embryonic kidney cells 293 at a concentration of 20 µM with no observed toxicity in Vero cells at 10 µM. The experimental results are accompanied with predicted favorable pharmacokinetic descriptors and drug-likeness parameters. In conclusion, this study provides the first generation of MERS-CoV fusion inhibitors with potencies in the low micromolar range.

• Journal of Embryo Transfer
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• v.15 no.1
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• pp.23-31
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• 2000

This study was conducted to investigate the effects of quiescent treatment of donor cells and activation treatment time of recipient cytoplasm on nuclear remodeling and in vitro development of somatic cell-cloned bovine embryos. Serum starved, confluent and nonquiescent cycling adult skin cells were teansferred into enucleated oocytes. Nuclear transfer oocytes were activated at 30 min, 1 and 2 hrs after electrofusion. Some nuclear transfer embryos(23% to 35%) extruded a polar body, which was not affected by quiescent treatment of donor cells and activiation time of recipient cytoplasm. About 68% of nuclear transfer embryos fused with a serum starved cells has a chromatin clump, but which was not different from embryos fused with confluent(51%) and nonquiescent(47%) cells. The proportion of embryos with a single chromatin clump was sightly increased when nuclear transfer embryos were activated within 30 min after fusion(69%) compared to those were activated at 1 and 2 hrs after fusion, but there was not significantly different. Development rates to the blastocyst stage were 8.6% and 15.9% when serum starved and confluent cells were transferred, which were higher than that of control group. Developmental rate to the blastocyst stage was higher in embryos were activated within 30 min after fusion (17.3%) compared to those of embryos were activated at 1 and 2 hrs after fusion (P<0.05). From the present result, it is suggested that quiescent treatment of donor cells and activation time of recipient cytoplasm can affect the in vitro development. Quiescent plasm activation within 30 min after fusion could increase the number of embryos with a normal chromation structure, which results in increased in vitro development.

• Corrosion Science and Technology
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• v.7 no.3
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• pp.162-167
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• 2008

Degradable implants have been in use for bone surgery for decades. However, degradable metal implants are one of the new research areas of biomaterials science. Magnesium has good biocompatibility due to its low toxicity, and it is a corroding, i.e. dissolvable, metal. Furthermore, magnesium is needed in human body, and naturally found in bone tissue. There have been some published reports also asserting the potential bone cell activation or bone healing effect of high magnesium ion concentrations. The classic method for achieving intertransverse process fusion involves autogenous iliac crest bone graft. Several investigations have been performed to enhance this type of autograft fusion. However, there is no research which has been undertaken to investigate the efficiency of pure magnesium particles in posterolateral spinal fusion. In this study, corrosion behavior of magnesium metal at the bone interface, the possibility of new bone cell formation and the degree of effectiveness in producing intertransverse process lumbar fusion in a sheep model have been investigated. Cortical bone screws were machined from magnesium alloy AZ31 extruded rod and implanted to hip-bones of sheep via surgery. Three months after surgery, the bone segments carrying these screws were removed from the sacrificed animals. Samples were sectioned to reveal Mg/bone interfaces and investigated using optical microscope, SEM-EDS and radiography. Optical and SEM images showed that there was a significant amount of corrosion on the magnesium screw. The elemental mapping results indicate, due to the presence of calcium and phosphorus elements, that there exists new bone formation at the interface. Furthermore, sixteen sheep were subjected to intertransverse process spinal fusions with pedicle screw fixation at various locations along their spines. Each animal was treated with 5cc autograft bone at one fusion level and 1cc magnesium+5cc autograft bone at the other. Six months after surgery, bone formation was evaluated by gross inspection and palpation, and radiological, histological, scanning electron microscopic and x-ray diffraction analyses. It may be stated that the potential for using useful corrosion of magnesium alloys in medical applications is expected to be significant.

• Journal of Embryo Transfer
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• v.15 no.3
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• pp.247-253
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• 2000

This study was undertaken to optimize enucleation and reconstitution methods for the production of cloned mice by somatic cell nuclear transfer Outbred ICR mouse oocytes at the metapahse- II stage were retrieved from female mice superovulated by PMSG and hCG. In Experiment 1, oocytes were enucleated in medium supplemented with cytochalasin B (CCB) of 3 levels (0, 7.5 or 15 $\mu\textrm{g}$/mL), and higher rate of encleation was obtained at 7.5 and 15 $\mu\textrm{g}$/mL than at $\mu\textrm{g}$/mL. In Experiment 2, oocytes enucleated in 7.5 $\mu\textrm{g}$/mL CCB-containing medium were reconstituted with different types of somatic cell by following methods; 1) cumulus cells by direct cell injection, 2) cumulus cells by electric fusion (1.25 kV/cm, 2 pulses for each 70 $mutextrm{s}$) or 3) STO cells by the electrofusion. Electrofusion of STO cells with enucleated oocytes yielded the greatest (P<0.05) rate of reconstitution without lysis (76%) than any other combinations. Although significant decrease in the rate of somatic cell introduction was found, the electrofusion of cumulus cells yielded better rate of reconstitution than direct injection (0 vs. 18%). In Experiment 3, the duration of electric stimulation for the fusion was changed to either 50 $mutextrm{s}$ or 90 $mutextrm{s}$, but no significant improvement of reconstitution efficacy was obtained. In conclusion, this study showed that ICR mouse oocytes could be used for the production of reconstituted oocytes and a fusion method of 1.25 KV/cm with 2 pulses using 570 cell was the optimal.

• Biomedical Science Letters
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• v.2 no.2
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• pp.175-185
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• 1996

The mitogen-activated protein(MAP) kinase signal transduction pathway represents an important mechanism by which mitogen, such as serum and PMA, regulate cell proliferation and differentiation. Target substrates of the MAP kinase are located within several compartments containing plasma membranes and nucleus. We now report that serum addition induces proliferation of the P388 murine leukemia cell, but PMA does not, while both serum and PMA treatment cause translocation of the MAP kinase, mainly p42$^{mapk}$ isoform, from cytosol into the nucleus, which was monitored by immunoblot analysis using polyclonal anti-ERK1 antibodies. We investigated whether the MAP kinase was capable of phosphorylating c-Jun protein and GST-fusion proteins, the P562$^{kk}$N-terminal peptides (1-77 or 1-123 domain) of the T cell tyrosine kinase, using the partially purified MAP kinase by SP-sephadex C-50, phenyl superose and Mono Q column chromatography. We found that the partially purified MAP kinase was able to phosphorylate c-Jun protein and the GST-fusion protein expressed using E.coli DH5$\alpha$ which is transformed with pGEX-3Xb plasmid vector carrying of p562$^{kk}$N-terminal peptide-encoding DNA. These results imply that tyrosine kinase receptor/Ras/Raf/MAP kinase pathway is a major mechanism for mitogen-induced cell proliferation in P388 murine leukemia cell and that the various MAP kinase isoforms may have their own target substrates located in distinct subcellular compartments.

• The Korean Journal of Mycology
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• v.15 no.2
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• pp.80-86
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• 1987

The author isolated high cellulolytic fungi from natural sources and determined optimal condition of protoplast formation and fusion as fundamental step for improvement of the isolated it's cellulolytic ability. Three different cellulolytic fungi, such as Aspergillus sp., Penicillium sp. and Trichoderma sp., were isolated from soil. Their cellulolytic activities were compared with that of Aspergillus niger which was useful industrially and had cellulase activity. It was Aspergillus sp. that showed the highest activity of all these four fungi. And then it was followed by Penicillium sp., Trichoderma sp., and Aspergillus niger in order. An auxotrophic mutant of Aspergillus sp. was obtained by UV mutagenesis method. Having try to produce protoplast from mycelia, the author found that ${\beta}-glucuronidase$, at pH 6.0, was effective cell-wall lytic enzyme. And the optimal concentration of this enzyme was 5,000 unit/ml. Regeneration rates of wild type, met. auxotroph and arg. auxotroph, in presence of osmotic stabilizer, were 7. 0%, 7. 5% and 5.2%, respectively. PEG with M.W. 6,000 was effective stimulator for protoplast fusion in the concentration of 30% (W IV). In such a condition, we obtained 1.2% cell fusion rate.