• Journal of Microbiology and Biotechnology
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• 제18권10호
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• pp.1729-1734
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• 2008

Chitosan, a cationic polysaccharide, has been widely used as a dietary supplement and in a variety of pharmacological and biomedical applications. The antifungal activity and mechanism of action of low molecular weight water-soluble chitosan (LMWS-chitosan) were studied in fungal cells and vesicles containing various compositions of fungal lipids. LMWS-chitosan showed strong antifungal activity against various pathogenic yeasts and hyphae-forming fungi but no hemolytic activity or cytotoxicity against mammalian cells. The degree of calcein leakage was assessed on the basis of lipid composition (PC/CH; 10:1, w/w). Our result showing that LMWS-chitosan interacts with liposomes demonstrated that chitosan induces leakage from zwitterionic lipid vesicles. Confocal microscopy revealed that LMWS-chitosan was located in the plasma membrane. Finally, scanning electron microscopy revealed that LMWS-chitosan causes significant morphological changes on fungal surfaces. Its potent antibiotic activity suggests that LMWS-chitosan is an excellent candidate as a lead compound for the development of novel anti-infective agents.

• 한국화재소방학회:학술대회논문집
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• 한국화재소방학회 1996년도 학술발표회
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• pp.57-61
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• 1996

Our goal was to make a cost-effective automatic fire extinguishing system for the engine compartment use of automobiles. We designed this system for the engine compartment. This system consists of 1)foam extinguisher, 2)four nozzles, 3)a pipe arrangement, and 4)an extinguishing device which is equipped with a glass bulb as detector. First and foremost, the extinguishing device was carefully designed to keep the system cost to a minimum. Second, a AFFF foam extinguisher was used because no other fire-fighting agents proved effective against fire in the engine compartment. The AFFF(Aqueous Film Forming Foam) agent which was used in the extinguisher is the 3M company's Light Water. We sought, however, to make other foams by using Halon 1301 and Halon alternatives such as HCFC Blend A, HFC-227ea. We selected these alternatives instead of air in order to raise the expansion ratio of the AFFF agent. By these means we discovered that it is possible to increase the expansion ration of the AFFF agent up to 44:1. We then demonstrated that our automatic fire extinguishing system is the most effective and lowest cost-system yet devised for passenger cars.

• Journal of Microbiology and Biotechnology
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• 제26권1호
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• pp.44-55
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• 2016

Bacillus cereus is a gram-positive, rod-shaped, spore-forming bacterium that has been isolated from contaminated fermented soybean food products and from the environment. B. cereus produces diarrheal and emetic toxins and has caused many outbreaks of foodborne diseases. In this study, we investigated whether B. amyloliquefaciens RD7-7, isolated from rice doenjang (Korean fermented soybean paste), a traditional Korean fermented soybean food, shows antimicrobial activity against B. cereus and regulates its toxin gene expression. B. amyloliquefaciens RD7-7 exhibited strong antibacterial activity against B. cereus and inhibited the expression of B. cereus toxin-related genes (groEL, nheA, nheC, and entFM). We also found that addition of water extracts of soybean and buckwheat soksungjang (Korean fermented soybean paste made in a short time) fermented with B. amyloliquefaciens RD7-7 significantly reduced the growth and toxin expression of B. cereus. These results indicate that B. amyloliquefaciens RD7-7 could be used to control B. cereus growth and toxin production in the fermented soybean food industry. Our findings also provide a basis for the development of candidate biological control agents against B. cereus to improve the safety of fermented soybean food products.

• Journal of Contemporary Eastern Asia
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• 제12권2호
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• pp.35-47
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• 2013

This study aims to understand haiku phenomena from the viewpoint of communication, which emerges from reciprocal relationships among haiku poets, haiku societies, media on haiku, and other establishments relating to haiku. Such an analytic point of view, which tries to consider both the operation of each autonomous agent and that of the whole system consisted by the agents, is included in the realm of second-order cybernetics. The operation of a system cannot be reduced completely to a system's individual components, which is why such a viewpoint is required. Fundamental informatics, which is employed as a theoretical framework, and two haiku movements, which include shin keiko haiku ("new-trend" haiku) and dento ha haiku (Hototogisu-school haiku), forming an important part of modern haiku history, are the focus of this study. As a result, modern haiku history is considered to be an evolution of a haiku system, whose main incentive is an awareness of the production mechanism of haiku communication occurring through second-order observations in the system. This study also illuminates how haiku poets, haiku societies, and media covereage of haiku play roles in the evolution of the haiku system.

• 동국한의학연구소논문집
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• 제9권
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• pp.1-23
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• 2000

Osteoporosis is a common disorder characterized by reduced bone mineral density, deterioration of the microarchitecture of bone tissue and increased risk of fracture. The aim of treatment of osteoporosis is to maintain and, ideally, to restore bone strength safely. In recent years the role of polypeptide growth factors in bone metabolism has begun to appear. It has been proposed that alterations in the expression or production of growth factor can modulate the proliferation and activity of bone forming cells. Thus, the role of structurally diverse peptides for the management and diagnosis of osteoporosis has attracted the attention of many investigators. This paper reviews numerous findings concerning the use of polypeptides, hormones, and growth factors, for the management of osteoporosis. Many of the compounds mentioned here are experimental prototypes of new therapeutic classes. Though it is unlikely that some of the compounds may ever be used clinically, development of safe and efficacious agents in each class will define the future course of therapy for osteoporosis.

• 대한의생명과학회지
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• 제17권4호
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• pp.363-366
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• 2011

Eradication of $H.$ $pylori$, usually carried out by using antimicrobial agents, is essential for preventing gastric ulcers and cancers. The $H.$ $pylori$ isolates, however, have continuously grown antimicrobial resistance, which have caused difficulty in treating the bacteria and in turn, photodynamic therapy (PDT) has been found to be effective in inducing deaths of variety of bacteria. After PDT treatment, the number of colony forming units (CFU), the morphologic changes, and flow cytometry were observed. In the PDT group containing 100 and 200 ${\mu}g$/ml photogem, no live $H.$ $pylori$ was observed, while 10 and 50 ${\mu}g$/ml photogem were only partially effective. $H.$ $pylori$ of the PDT group also displayed distortion and shrinkage in morphology. This study demonstrated that photogem-mediated PDT effectively induces deaths of $H.$ $pylori$.

• Journal of Oral Medicine and Pain
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• 제21권1호
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• pp.123-131
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• 1996

Bacteremia occurs in a wide variety of clinical procedures in oral cavity. Reduction of the number of causative microorganisms of infective endocarditis in oral cavity by local administration of antimicrobial agents decreases the magnitude of bacteremia and possibility of infective endocarditis. The effects of chlorhexidine on Streptococcus sanguis, Streptococcus mitis, Streptococcus mutans, Streptococcus oralis, Streptococcus gordonii, Staphylococcus aureus, and Staphylococcus epidermis were investigated by measurement of turbidity. The effects of 0.1% chlorhexidine gargling for 7 days on oral bacterial flora, total streptococci, S. mutans, S. aureus, and S. epidermis in whole saliv a of 7 healthy human subjects, were investigated by measurement of Colony Forming Units (CFU). The obtained results were as follows : 1. Chlorhexidine showed significant antimicrobial effects on Streptococcus snaguis, Streptococcus mitis, Streptococcus mutans, Streptococcus oralis, Streptococcus gordonii, Staphylococcus aureus, and Staphylococcus epidermis. However, the effects on S. sanguis and S. gordonii were not apparent compared with other microorganisms. 2. Oral gargling of 0.1% chlorhexidine decreased the CFU values of normal oral bacterial flora, total streptococci, S. mutans, S. aureus, and S. epidermis in whole saliva. The antimicrobial effects were significant after 4 days of chlorhexidine gargling. 3. Local antimicrobial administration in addition to systemic antibiotic prophylaxis can be highly recommended as an effective adjunct regimen for prevention of infective endocarditis.

• 대한핵의학회지
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• 제26권1호
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• pp.8-13
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• 1992

Low doses of ionizing radiation from external or internal sources cause heterogeneous distribution of energy deposition events in the exposed biological system. With the cell being the individual element of the tissue system, the fraction of cells hit, the dose received by the hit, and the biological response of the cell to the dose received eventually determine the effect in tissue. The hit cell may experience detriment, such as change in its DNA leading to a malignant transformation, or it may derive benefit in terms of an adaptive response such as a temporary improvement of DNA repair or temporary prevention of effects from intracellular radicals through enhanced radical detoxification. These responses are protective also to toxic substances that are generated during normal metabolism. Within a multicellular system, the probability of detriment must be weighed against the probability of benefit through adaptive responses with protection against various toxic agents including those produced by normal metabolism. Because irradiation can principally induce both, detriment and adaptive responses, one type of affected cells may not be simply summed up at the expense of cells with other types of effects, in assessing risk to tissue. An inventory of various types of effects in the blood forming system of mammals, even with large ranges of uncertainty, uncovers the possibility of benefit to the system from exposure to low doses of low LET radiation. This experimental approach may complement epidemiological data on individuals exposed to low doses of ionizing radiation and may lead to a more rational appraisal of risk.

• Journal of Microbiology and Biotechnology
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• 제26권5호
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• pp.953-958
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• 2016

Chitosan-based film-forming gel is regarded as a promising vehicle for topical delivery of antimicrobial agents to skin wounds, since it protects from microbial infection and the cationic polymer itself possesses antibacterial activity. In this study, possible synergistic interaction against common skin pathogens between the cationic polymer and tyrothricin (TRC), a cyclic polypeptide antibiotic, was investigated, by determining the concentration to inhibit 90% of bacterial isolates (MIC). The addition of the polysaccharide to TRC dramatically reduced the MIC values of TRC by 1/33 and 1/4 against both methicillin-resistant and methicillin-susceptible Staphylococcus aureus, respectively. The synergism of TRC and chitosan combination against both strains was demonstrated by the checkerboard method, with a fractional inhibitory concentration index below 0.5. Moreover, co-treatment of TRC and chitosan exhibited antibacterial activity against Pseudomonas aeruginosa, due to the antibacterial activity of chitosan, whereas TRC itself did not inhibit the gram-negative bacterial growth. These findings suggested that the use of chitosan-based film for topical delivery of TRC could be an alternative to improve TRC antimicrobial activity against strains that are abundant in skin wounds.

• Journal of Microbiology and Biotechnology
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• 제24권8호
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• pp.1059-1064
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• 2014

Staphylococcus aureus is a major human pathogen, implicated in both community and hospital acquired infections. The therapy for methicillin-resistant Staphylococcus aureus (MRSA) infections is becoming more difficult because of multidrug resistance and strong biofilm-forming properties. Schiff bases have attracted attention as promising antibacterial agents. In this study, we investigated the in vitro activity of taurine-5-bromosalicylaldehyde Schiff base (TBSSB) against MRSA. The minimum inhibitory concentrations (MIC) and minimum bactericidal concentration (MBC) were determined using a microtiter broth dilution method. TBSSB effectively inhibited planktonic MRSA, with an MIC of $32{\mu}g/ml$. The time-kill curve confirmed that TBSSB exhibited bactericidal activity against MRSA. TBSSB was also found to significantly inhibit MRSA biofilm formation at 24 h, especially at $1{\times}MIC$ and sub-MIC levels. Furthermore, scanning electron microscopy and transmission electron microscopy showed remarkable morphological and ultrastructural changes on the MRSA cell surface, due to exposure to TBSSB. This study indicated that TBSSB may be an effective bactericidal agent against MRSA.