• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.25 no.5
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• pp.362-367
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• 2016

Recently, wireless charging systems have expanded their applications from household electrical appliances to outdoor activity devices. In wireless charging systems, solar cells have versatile advantages, such as abundant raw materials within the earth, reasonable prices of products, and highest power conversion efficiency. In this study, the photovoltaic effect between a silicon solar cell and a photon of infrared wavelength was simulated using a Shockley diode equation. A solar cell power charging system was then set up to: 1) clarify mechanisms of the charging interaction based on the photovoltaic effect with a laser source, and 2) verify interdependency of the parameters: laser settings and geometrical position between a solar cell and the laser. As was observed, the solar cell generates more power when the photon was irradiated uniformly, intensively, and vertically on the surface of the solar cell.

• BMB Reports
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• v.57 no.2
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• pp.104-109
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• 2024

Gefitinib exerts anticancer effects on various types of cancer, such as lung, ovarian, breast, and colon cancers. However, the therapeutic effects of gefitinib on cervical cancer and the underlying mechanisms remain unclear. Thus, this study aimed to explore whether gefitinib can be used to treat cervical cancer and elucidate the underlying mechanisms. Results showed that gefitinib induced a caspase-dependent apoptosis of HeLa cells, which consequently became round and detached from the surface of the culture plate. Gefitinib induced the reorganization of actin cytoskeleton and downregulated the expression of p-FAK, integrin β1 and E-cadherin, which are important in cell-extracellular matrix adhesion and cell-cell interaction, respectively. Moreover, gefitinib hindered cell reattachment and spreading and suppressed interactions between detached cells in suspension, leading to poly (ADP-ribose) polymerase cleavage, a hallmark of apoptosis. It also induced detachment-induced apoptosis (anoikis) in C33A cells, another cervical cancer cell line. Taken together, these results suggest that gefitinib triggers anoikis in cervical cancer cells. Our findings may serve as a basis for broadening the range of anticancer drugs used to treat cervical cancer.

• Bulletin of the Korean Chemical Society
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• v.30 no.3
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• pp.567-572
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• 2009

In this study, the effects of counter ion valency of the electrolyte on the colloidal repulsion between two parallel cylindrical particles were investigated. Electrostatic interactions of the cylindrical particles were calculated with the variation of counter ion valency. To calculate the electrical repulsive energy working between these two cylindrical particles, Derjaguin approximation was applied. The electrostatic potential profiles were obtained numerically by solving nonlinear Poission-Boltzmann (P-B) equation and calculating middle point potential and repulsive energy working between interacting surfaces. The electrical potential and repulsive energy were influenced by counter ion valency, Debye length, and surface potential. The potential profile and middle point potential decayed with the counter ion valency due to the promoted shielding of electrical charge. On the while, the repulsive energy increased with the counter ion valency at a short separation distance. These behaviors of electrostatic interaction agreed with previous results on planar or spherical surfaces.

• Journal of Microbiology and Biotechnology
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• v.10 no.6
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• pp.844-850
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• 2000

The specific binding and internalization of viral particles is an essential step for the successful infection of viral pathogens. In the case of the hepatitis B virus (HBV), virions bind to the host cell via the preS domain of the viral surface antigen and are subsequently internalized by endocytosis. HBV-preS specific receptors are primarily expressed on hepatocytes, however, viral DNA and proteins have also been detected in extrahepatic sites, suggsting that celluar recepators for HBV may also exist on extrahepatic cells. Recently, an EBV-transformed B-cell line was identified onto which the preS region binds in a receptor-ligand specific manner. In this study, this specific interaction was further characterized, and the binding region within the preS protein was locaized. Also the internalization after host cell attachment was visualized and analyzed by fluorescence-labeled HBV-preS1 proteins using confocal microscopy. Energy depletion by sodium azide treatment effectively inhibited the internalization of the membrane-bound preS1 ligands, thereby indicating an energy-dependent receptor-mediated endocytotic pathway. Accordingly, the interaction of HBV-pres! with this specific B-cell line may serve as an effective model for an infection pathway in extrahepatic cells.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2000.04a
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• pp.29-34
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• 2000

This paper describes a numerical study to make clear the characteristics of flow around a high speed catamaran hull advancing on calm water. The simulation is carried out at Froude number of 0.5 with a separation to length rations of 0.2 to 0.5. To simulate the flows, the Navier-Stokes solver is employed in which the free surface condition is included. Computations are performed in a rectangular grid system based grid system based on the Marker & Cell method. For the validation, the computation results are compared with the experiments.

• Journal of Dental Rehabilitation and Applied Science
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• v.25 no.4
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• pp.361-374
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• 2009

For successful osteogenesis around the implants, interaction between implant surface and surrounding tissue is important. Biomechanical bonding and biochemical bonding are considered to influence the response of adherent cells. But the focus has shifted surface chemistry. The purpose of this study is to evaluate the MC3T3-E1 osteoblast like cell responses of magnesium (Mg) ion implanted titanium surface produced using a plasma source ion implantation method. Commercially pure titanium disc was used as substrates. The discs were prepared to produce four different surface, A: Machine turned surface, B: Mg implanted surface, C: sandblasted surface, D: sandblasted and Mg implanted surface. MC3T3 El osteoblastic like cells were cultured on the disc specimens. Cell adhesion, proliferation, differentiation, and synthesis of extracellular matrix were evaluated. The cell adhesion morphology was evaluated by SEM. RT PCR assay was used for assessment of cell adhesion, proliferation and differentiation. ALP activity was measured for cell differentiation. The results of this study were as follows: 1. SEM showed that cell on Mg ion groups was more proliferative than that of non Mg ion groups. On the machine turned surface, cell showed some degree of contact guidance in aligning with the machining grooves. 2. In RT PCR analysis, osteonectin and c-fos mRNA were more expressed on sandblasted and Mg ion implanted group. 3. ALP activity was not significantly different among all groups. Within the limitations of this study, the following conclusions were drawn: It might indicate Mg ion implanted titanium surface induce better bone response than non Mg ion groups.

• Journal of Yeungnam Medical Science
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• v.2 no.1
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• pp.175-181
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• 1985

Agrobacterium tumefaciens induces cancerous growths called crown galls at wound sites on dicotyledonous plants. A large plasmid called Ti plasmid is responsible for virulence. Upon tumor induction, part of the plasmid, termed T-DNA, becomes integrated into plant genome and its genetic sequences are expressed. These properties allow Ti plasmids to be used as gene vectors in plants. Several in vitro methods for the transfer of Ti plasmid into plant cell have been developed. One of them is the treatment of bacterial spheroplasts and plant protoplasts mixture with polyethylene glycol that is generally used as fusogen in cell-to-cell fusion. Several workers investigated the interaction of bacterial spheroplasts with plant protoplasts in the presence of polyethylene glycol and suggested that the interaction is not fusion but endocytosis. In this report we observed the interaction of Agrobacterium tumefaciens spheroplasts with Nicotiana tabacum protoplasts by electron microscope. Agrobacterium tumefaciens spheroplasts and Nicotiana tabacum protoplasts were prepared and mixed in the presence of polyethylene glycol and high pH-high $Ca^{2+}$ buffer. Then the interaction of the spheroplasts with the protoplasts was examined by transmission electron microscope. After the treatment of polyethylene glycol the spheroplasts adhered to the surface of the protoplasts and then they were engulfed by the protoplasts. After the high pH-high $Ca^{2+}$ buffer treatment the engulfed spheroplasts lost their cell integrity. No fusion process was observed. Thus all these observations suggest that the introduction process of Agrobacterium tumefaciens spheroplasts into Nicotiana tabacum protoplasts with the aid of polyethylene glycol is endocytosis.

• IMMUNE NETWORK
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• v.2 no.1
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• pp.25-34
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• 2002

Background: Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by synovial hyperplasia and joint destruction. The synovial fibroblasts express cell adhesion molecules and have a role in adhesive interation with inflammatory cells in synovial tissue. It has been suggested that hypoxic conditioins are thought to exist in arthritic joints, and several studies indicate that reactive oxygen species (ROS) produced in hypoxic condition can initiate events that lead to pro-adhesive changes via increased expression of adhesion molecules. So, this study wsa designed to examine whether antioxidant can inhibit hypoxia-induced expression of ICAM-1 in cultured human synovial fibroblasts. Methods: Synovial fibroblasts were isolated from synovial tissue in patients with RA and cultured at hypoxic condition. Antioxidant, PDTC (pyrrolidine dithiocarbamate) were pre-treated for an hour before the hypoxic culture and synovial fibroblasts were harvested at 0, 6, 12, 24, 48 hours time points. Cell surface ICAM-1 expression in synovial fibroblasts was examined by the flow cytometric analysis. To analyse the expression of ICAM-1 mRNA, reverse-transcriptase polymerase chain reaction (RT-PCR) was performed. The levels of cytokines in culture supernatants were measured by ELISA, and activation of NF-${\kappa}B$ was analysed by electrophoretic mobility shift assay. The adhesive reaction between synovial fibroblasts and lymphocytes was assayed by measurement of fluorescent intensity of BCECF-AM in lymphocytes. Results: Hypoxic stimuli up-regulated the ICAM-1 expression as well as the adhesive interaction of human synvial fibroblasts to lymphocytes in a time-dependent manner, and PDTC inhibited hpyoxia-induced ICAM-1 expression and cell-cell interaction. PDTC also inhibited the hypoxia-induced activation of intracellular transcription factor, NF-${\kappa}B$. PDTC decreased the amount of hypoxia-induced production of IL-$1{\beta}$ and TNF-${\alpha}$. Conclusion: These studies demonstrate that PDTC inhibit the hypoxia-induced expression of the adhesion molecule, ICAM-1 and activation of NF-${\kappa}B$ in cultured human synovial fibroblasts.

• Journal of Periodontal and Implant Science
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• v.29 no.4
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• pp.803-823
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• 1999

In order to reveal immunopathogenesis of periodontal tissue destruction, it is important to clarify the molecular mechanism of trafficking and retention of activated leukocytes, including monocytes/macrophages. Gingival fibroblasts may be involved in the regulation of inflammatory cell accumulation in the extravascular periodontal connective tissues via cytokine production and surface expression of adhesion molecules. In this study, it was investigated the molecular basis for the adhesive interactions between monocytes and fibroblasts such as peri-odontal ligament fibroblast(PDLF), human gingival fibroblast(HGF), and human dermal fibroblast(HDF). First, it was examined the evidence whether monocyte-fibroblast cell contact may cause signal transduction in fibroblasts. Being directly in contact with fixed human monocyte cell line THP-1, or U937, upregulation of IL-6 production, $TNF-{\alpha}$ mRNA expression and increased cell proliferation could be seen for fibroblasts. IL-6 production induced by monocyte- fibroblast coculture were further increased when fibroblasts had been pretreated with $IFN-{\gamma}$ or $IL-1{\beta}$ , and monocytes with LPS. Next, it was examined the expression of ICAM-1 which has been known to be involved in accumulation and activation of leukocytes in inflammatory diseases such as periodontitis. ICAM-1 was upregulated up to 10-fold on PDLF, HGF, and HDF by exposure to $IFN-{\gamma}$ or $IL-1{\beta}$. Furthermore, anti-ICAM-1 monoclonal antibody clearly blocked cocultureinduced IL-6 production by fibroblasts, suggesting that $ICAM-1/{\beta}_2$integrin pathway is involved in periodontal fibroblastmonocyte interaction. Overall, these findings provide evidence that periodontal fibroblasts could be involved in the accumulation and retention of monocytes/macrophages in periodontal inflammatory lesion at least in part by ICAM-1 expression. In addition, periodontal fibroblast-monocyte interaction could cause activation signals in fibroblasts intracellularly which result in cytokine production and cell proliferation. Thus, periodontal fibroblasts are speculated to play an important role in immunoregulation and tissue destruction in chronic periodontal diseases by interaction with monocytes/macrophages.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.29-29
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• 2003

Incompatible plant-pathogen interactions result in the rapid cell death response known as hypersensitive response (HR) and activation of host defense-related genes. To understand the molecular and cellular mechanism controlling defense response better, several approaches including isolation and characterization of novel genes, promoter analysis of those genes, protein-protein interaction analysis and reverse genetic approach etc. By using the yeast two-hybrid system a clone named Tsipl, Tsil -interacting protein 1, was isolated whose translation product apparently interacted with Tsil, an EREBP/AP2 type DNA binding protein. RNA gel blot analysis showed that the expression of Tsipl was increased by treatment with NaCl, ethylene, salicylic acid, or gibberellic acid. Transient expression analysis using a Tsipl::smGFP fusion gene in Arabidopsis protoplasts indicated that the Tsipl protein was targeted to the outer surface of chloroplasts. The targeted Tsipl::smGFP proteins were diffused to the cytoplasm of protoplasts in the presence of salicylic acid (SA) The PEG-mediated co-transfection analysis showed that Tsipl could interact with Tsil in the nucleus. These results suggest that Tsipl-Tsil interaction might serve to regulate defense-related gene expression. Basically the useful promoters are valuable tools for effective control of gene expression related to various developmental and environmental condition.(중략)