• The Journal of Korean Society of Virology
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• v.30 no.1
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• pp.83-99
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• 2000

A defective HIV-1 helper virus DNA, pHyPC, was assembled by deleting the RNA packaging signal, env, nef and the 3'LTR sequences. HIV-1 like virus particles that carry the HIV-1 receptor, CD4 were generated by co expression of pHyPC and plasmid DNAs encoding different chimeric CD4 proteins. The CD4 particles, sharing the CD4 ectodomain, precisely fused to different membrane anchors. CD4(+) particles specifically bound to HIV-1 Env expressing cells, but any signs of infection into these cells were not detected. Binding was only partially blocked by either polyclonal anti-CD4 antibodies or by high concentrations of soluble CD4. Surprisingly, CD4(+) particles also adsorbed to HeLa, CHO, NIH3T3 and COS-7 cells in the absence of HIV-1 Env expression. Adsorption was comparable in strength and speed to the highly specific CD4-Env interaction. CD4(-) particles exhibited only background levels of binding. Cell binding was CD4. dependent, but it was independent of the cell type from which the CD4(+) particles originated. Interestingly, CD4-dependent/Env-independent binding was only found when CD4 was present on virus particles. This suggests that the micro-environment of CD4 on virus particles uniquely expose this new cell binding activity. Its high affinity could explain in part why infection of Env(+) cells by CD4(+) particles was not detected. Further experiments will be required to evaluate whether this strong membrane interaction could represent one step in the multiple-step viral entry process.

• Parasites, Hosts and Diseases
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• v.39 no.1
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• pp.13-21
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• 2001

Pneumocystis carinii causes serious pulmonary infection in immuno-suppressed patients. This study was undertaken to observe the cytoskeletal proteins of P. carinii by immune-electron microscopy. P. carinii infection was experimentally induced by immunosuppression of Sprague-Dawley rats for seven weeks, and their lungs were used for the observations of this study. The gold particles localized actin, tropomyosin, and tubulin. The actin was irregularly scattered in the cytoplasm of the trophic forms but was much more concentrated in the inner space of the cell wall of the cystic forms called the inner electron-lucent layer No significant amount of tropomyosin was observed in either trophic forms or cystic forms. The tubulin was distributed along the peripheral cytoplasm and filopodia of both the trophic and cystic forms rather than in the inner side of the cytoplasm. Particularly, in the cystic forms, the amount of tubulin was increased and located mainly in the inner electron-lucent layer of the cell wall where the actin was concentrated as well. The results of this study showed that the cell wall of P carinii cystic forms is a structure whose inner side is rich in actin and tubulin. The location of the actin and tubulin in P. carinii suggests that the main role of these proteins is an involvement in the protection of cystic forms from the outside environment by maintaining rigidity of the cystic forms.

• The Korean journal of helicobacter and upper gastrointestinal research
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• v.18 no.3
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• pp.150-156
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• 2018

Precision medicine stands for 4Ps - precise, preventive, participatory, and personal; in which "precision" is important because the current modern medicine starts from "trial and error," and "one does not fit all". Current targeted therapies for cancer have changed treatment approaches and led the precision medicine; however, clinical use of liquid biopsy, using blood or other liquid specimens to characterize circulating tumor cells (CTC) or tumor genes instead of biopsies of tumor tissues, still awaits availability of more information regarding non-invasive cancer detection and characterization, prediction of treatment response, monitoring the disease course and relapse possibilities, identification of mechanisms of drug resistance, and newer pathogenesis. In this review, we will introduce the basic concept of CTC, circulating cell free DNA, and exosomes and their possible application for gastric cancer relevant with Helicobacter pylori infection.

• Korean Journal of Pharmacognosy
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• v.50 no.3
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• pp.191-197
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• 2019

Sepsis, an infectious disease, is a life-threatening condition that arises when the response to infection causes injury to tissues and organs. The purpose of this study was to demonstrate whether ABHC-1 and ABHC-2, two functional extracts from herbal complex, have an anti-bacterial effect against Escherchia coli in vivo, in vitro experimental model. ABHC-1 and ABHC-2 showed the antibacterial activity against the bacteria by paper disc method. The minimum inhibitory concentration (MIC) was measured using alamar blue reagent. The MIC was shown at $60{\mu}g/ml$ from ABHC-1 and $500{\mu}g/ml$ from ABHC-2 against E. coli. We next examined the effect of ABHCs on the production of inflammatory cytokine, such as tumor necrosis $factor-{\alpha}$ ($TNF-{\alpha}$), which is related to the induction of inflammation, in RAW 264.7 cell. ABHC-1 and ABHC-2 increased $TNF-{\alpha}$ production of RAW 264.7 cell in a dose-dependent manner while two extract decreased $TNF-{\alpha}$ production in lipopolysaccharide (LPS)-stimulated RAW 264.7 cell in a dose-dependent manner. At a dose of $1{\times}10^8$ E. coli. i.p., non-treated mice were succumbed, while most of mice treated with ABHC-1 were survived. Therefore, our results suggest that ABHC-1 has anti-bacterial activity and can be a novel therapeutic agent against infectious diseases.

• Journal of Animal Reproduction and Biotechnology
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• v.37 no.3
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• pp.183-192
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• 2022

Lipopolysaccharide (LPS) is an endotoxin factor present in the cell wall of Gram-negative bacteria and induces various immune responses to infection. Recent studies have reported that LPS induces cellular stress in various cells including oocytes and embryos. Melatonin (N-acetyl-5-methoxytryptamine) is a regulatory hormone of circadian rhythm and a powerful antioxidant. It has been known that melatonin has an effective function in scavenging oxygen free radicals and has been used as an antioxidant to reduce the cytotoxic effects induced by LPS. However, the effect of melatonin on LPS treated early embryonic development has not yet been confirmed. In this study, we cultured mouse embryos in medium supplemented with LPS or/and melatonin up to the blastocyst stage in vitro and then evaluated the developmental rate. As a result of the LPS-treatment, the rate of blastocyst development was significantly reduced compared to the control group in all the LPS groups. Next, in the melatonin only treated group, there was no statistical difference in embryonic development and no toxic effects were observed. And then we found that the treatment of melatonin improved the rates of compaction and blastocyst development of LPS-treated embryos. In addition, we showed that melatonin treatment decreased ROS levels compared to the LPS only treated group. In conclusion, we demonstrated the protective effect of melatonin on the embryonic developmental rate reduced by LPS. These results suggest a direction to improve reproduction loss that may occur due to LPS exposure and bacterial infection through the using of melatonin during in vitro culture.

• The Plant Pathology Journal
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• v.26 no.2
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• pp.101-109
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• 2010

Protein phosphorylation is one of the major mechanisms for controlling many cellular processes in all living organisms. Mitogen-activated protein kinase (MAPK) cascades are known to transducer extracellular stimuli to several cellular processes, including cell division, differentiation as well as responses to various stresses. In plants, several studies have revealed that MAPK cascade pathways play an important role in responses against biotic and abiotic stresses, including wounding, pathogen infection, temperature, drought, salinity and plant hormones. It is also known that MAPK cascades-mediated signaling is an essential process in the resistance step to pathogens by regulating the activity of transcription factors. Here, the insights into the functions of MAPK cascade pathways in plant defense response signaling from Arabidopsis, tobacco and rice are described.

• Journal of Plant Biotechnology
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• v.4 no.4
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• pp.135-141
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• 2002

Agrobacterium-mediated transformation has been unsuccessful for monocot plants except for a few important crops such as barley, rice, maize and wheat. We discussed here that a successful transformation of monocots demands certain critical conditions. The requirements for an efficient transformation are a selection of target tissues competent for plant regeneration and Agrobacterium-infection, and various factors promoting Agrobacterium-infection. The factors were divided into two to activate Agrobacterium and to increase plant cell's susceptibility against Agrobacterium. Optimization of these factors significantly increased transformation efficiency of zoysia grass and rice plants. A technical improvement in transformation system for monocots will promote improvement of the breed as well as a study of gene functions in monocots.

• Proceedings of the Microbiological Society of Korea Conference
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• 2001.11a
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• pp.97-101
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• 2001

The fusion between viral envelope and target cell membrane is a central step of viral infection, and the fusion proteins located at viral envelope mediate such process. Gp41 of HIV is one of the fusion proteins whose structure and mechanism of membrane fusion had been extensively studied. Functionally important motives of gp41 are the N-terminus fusion peptide, the coiled-coil and the membrane proximal C-peptide regions. The role of these regions during the fusion process had been thoroughly examined. Specially, insertion of the fusion peptide into membrane and conformational change of the coiled-coil and C-peptide regions are assumed to be critical for the fusion mechanism. In addition, the coiled-coil region has been shown to interact with membrane, and the C-peptide region regulates the interaction in a dose dependent manner. Furthermore, fusion defective mutations of the coiled-coil region dramatically changed its binding affinity to membrane. These results suggested that the membrane binding property of the coiled-coil region is important for the fusion activity of gp41, and such property could be modulated by the interaction with the C-peptide region.

• Journal of Sericultural and Entomological Science
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• v.40 no.1
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• pp.60-62
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• 1998

To understand expression of some early and late genes of Bombyx mori nuclear polyhedrosis virus (BmNPV) in the B. mori-derived BmN cell line, the transcripts were analyzed by polymerase chain reaction with synthetic primers. After infection, the transcript of early genes, which include p35, IE1 and helicase p143, was immediately detected in the infected cells. In addition, the transcript of late genes, which include p10 and polyhedrin, was also detected in just-infected cells. In conclusion, our results revealed that transcripts of early and late genes of BmNPV are immediately expressed from the cells after infection.

• Microbiology and Biotechnology Letters
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• v.19 no.6
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• pp.553-560
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• 1991

In the previous paper (10). a new temperate phage, Sigma FA1 had been isolated from B. circulans. Sigma FA1 had an icosahedral head with a diameter of about 70 nm, and a tail about 15 nm long, and beared a circularly permuted, linear duplex DNA. Signla FA1 killed sensitive cells by a single-hit process. Phage DNA injected into the cell immediately after infection was degraded slowly. Our results indicate that the killing action of Sigma FA1 is different from the phenomenon of abortive infection and suggest that the killing might be caused by a proteinaceous component of Sigma FA1.