• The Journal of Engineering Research
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• v.3 no.1
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• pp.181-187
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• 1998

Hydroxyapatite was used as implant materials, because it has a good biocompatibility and is similar to human bone. However it is not expected to have a high strength as implant materials because of a low fracture strength after sintering of HAp. Alumina ($\alpha$-alumina) shows a stable chemical properties and high strength in physiological environments. Thus it was tried to use a HAp coatings on Alumina substrate as implant materials. In this study, HAp was coated on Alumina substrate by lon Beam Assisted Deposition(IBAD). Then Ag was impregnated on HAp coating layer, which showed antimicrobial effects. To carry out the ion exchange of $Ag^+$ with $Ca^{2+}$ in HAp on the surface, HAp coated alumina substrate was immersed in 20ppm, 100ppm $AgNO_3$ solution at room temperature for 48 hours. Antimicrobial test was studied by using bacteria, which normally caused periprosthetic infections. The follwing bacteria was used in antimicrobial test. Escherichia coli, Pseudomonas aeruginosa (gram negative) and staphylococcus epidermidis (gram positive). Ag impregnated HAp shows very good antimicrobial effects against these bacteria. The surface structure of sample, which was treated in $AgNO_3$ solution was studied by SEM, XRD. Ag release curve was studied in Simulated Body Fluid (SBF) solution.

• Journal of Internet of Things and Convergence
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• v.6 no.2
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• pp.19-24
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• 2020

In the present study, using biological information of bacteria and biochemical information of chlorine dioxide gas, Gram-positive bacteria, e.g., Alloiococcus otitis, Erysipelothrix rhusiopathiae, Staphylococcus caprae, Staphylococcus lentus, and gram-negative bacteria, e.g., Acinetobacter baumannii complex, Aeromonas salmonicida, Brucella melitensis, Oligella ureolytica were used whether a plastic kit to release ClO₂ gas could inhibit their growth. Overall, chlorine dioxide gas showed about 99% inhibition of bacterial growth, with less than 10 CFU. However, it was found that Gram positive Alloiococcus otitis and Gram negative Aeromonas salmonicida had more than about 50 CFU. When comparing the results of experiments with several bacteria, it suggested that the concentration of chlorine dioxide gas would be at least 10 ppm to 400 ppm for the bacterial inhibition. The results of this study could be used as basic data to evaluate the clinical usefulness of chlorine dioxide gas. If this study helps with prior knowledge to help clinicians to recognize and prevent the presence of micro-organisms that cause infections in hospitals, it would be helpful for activities such as patient care as a convergence field. In the future, it is considered that the research results will be the basis for rapidly inhibiting the microbes infected with patients by utilizing data of the information of the microbes that are inhibited for chlorine dioxide gas.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.28 no.1
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• pp.61-79
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• 2018

Objectives: The objective of this study was to examine the effect of non-thermal dielectric barrier discharge(DBD) plasma on decontamination of Staphylococcus aureus(S. aureus) and Escherichia coli(E. coli) as common pathogens. Methods: This experiment was carried out in a chamber($0.64m^3$)designed by the authors. The plasma was continuously generated by a non-thermal DBD plasma generator(Model TB-300, Shinyoung Air tech, Korea). Suspensions of S. aureus and E. coli of 0.5 McFarland standard($1.5{\times}10^8CFU/mL$) were prepared using a Densi-Check photometer(bio $M{\acute{e}}rieux$, France). The suspensions were diluted1:1000 in sterile PBS solutions(approximately$10^{4-5}CFU/mL$) and inoculated on tryptic soy agar(TSA) in Petri dishes. The Petri dishes(80mm internal diameter)were exposed to the non -thermal DBD plasma in the chamber. Results: The results showed that 95% of S. aureus colonies were killed after a six-hour exposure to the DBD plasma. In the case of E. coli, it took two hours to kill 100% of the colonies. The gram-negative E. coli had a greater reduction than the gram-positive S. aureus. This difference may be due to the structure of their cell membranes. The thickness of gram-positive bacteria is greater than that of gram-negative bacteria. The S. aureus is more resistant to DBD plasma exposures than is E. coli. It should be noted that average concentrations of ozone, a byproduct of the DBD plasma generator, were monitored throughout the experiment and the results were well below the criteria, 50 ppb, recommended by the Korean Ministry of the Environment. Thus, non-thermal DBD plasma is deemed safe for use in hospital and public facilities. Conclusions: There was evidence that non-thermal DBD plasma can effectively kill S. aureus and E. coli. The results indicate that DBD plasma technology can greatly contribute to the control of infections in hospitals and other public and private facilities.

• Biomaterials Research
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• v.22 no.4
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• pp.328-336
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• 2018

Background: Biogenic fabrication of silver nanoparticles from naturally occurring biomaterials provides an alternative, eco-friendly and cost-effective means of obtaining nanoparticles. It is a favourite pursuit of all scientists and has gained popularity because it prevents the environment from pollution. Our main objective to take up this project is to fabricate silver nanoparticles from lichen, Usnea longissima and explore their properties. In the present study, we report a benign method of biosynthesis of silver nanoparticles from aqueous-ethanolic extract of Usnea longissima and their characterization by ultraviolet-visible (UV-vis), Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM) and scanning electron microscopy (SEM) analyses. Silver nanoparticles thus obtained were tested for antimicrobial activity against gram positive bacteria and gram negative bacteria. Results: Formation of silver nanoparticles was confirmed by the appearance of an absorption band at 400 nm in the UV-vis spectrum of the colloidal solution containing both the nanoparticles and U. longissima extract. Poly(ethylene glycol) coated silver nanoparticles showed additional absorption peaks at 424 and 450 nm. FTIR spectrum showed the involvement of amines, usnic acids, phenols, aldehydes and ketones in the reduction of silver ions to silver nanoparticles. Morphological studies showed three types of nanoparticles with an abundance of spherical shaped silver nanoparticles of 9.40-11.23 nm. Their average hydrodynamic diameter is 437.1 nm. Results of in vitro antibacterial activity of silver nanoparticles against Staphylococcus aureus, Streptococcus mutans, Streptococcus pyrogenes, Streptococcus viridans, Corynebacterium xerosis, Corynebacterium diphtheriae (gram positive bacteria) and Escherichia coli, Klebsiella pneuomoniae and Pseudomonas aeruginosa (gram negative bacteria) showed that it was effective against tested bacterial strains. However, S. mutans, C. diphtheriae and P. aeruginosa were resistant to silver nanoparticles. Conclusion: Lichens are rarely exploited for the fabrication of silver nanoparticles. In the present work the lichen acts as reducing as well as capping agent. They can therefore, be used to synthesize metal nanoparticles and their size may be controlled by monitoring the concentration of extract and metal ions. Since they are antibacterial they may be used for the treatment of bacterial infections in man and animal. They can also be used in purification of water, in soaps and medicine. Their sustained release may be achieved by coating them with a suitable polymer. Silver nanoparticles fabricated from edible U. longissima are free from toxic chemicals and therefore they can be safely used in medicine and medical devices. These silver nanoparticles were stable for weeks therefore they can be stored for longer duration of time without decomposition.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1997.04a
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• pp.40-47
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• 1997

New quinolones generally have a broad antibacterial spectrum against gram-positive, gram-negative, glucose-nonfermenting and anaerobic bacteria. Some of newly developed quinolones have potent activities against S. aureus including MRSA, S.pneumoniae including PRSP, B. fragilis, chlamydiae, mycoplasmas and mycobacteria as well, and show good activities against various strains resistant to antibacterial agents of other classes. Quinolones display postantibiotic effects in vitro and are bactericidal at concentrations similar to or twice that of the minimum inhibitory concentrations (MICs) for susceptible pathogens. In experimental murine infection models including systemic infections with various pathogens such as S. aureus, S. pyogenes, S. pneumoniae, E. coli and P. aeruginosa, quinolones have shown good oral efficacy as well as parenteral efficacy. Good oral absorption and good tissue penetration of quinolones account for good therapeutic effects in clinical settings. The target of quinolones are two structurally related type II topoisomerases, DNA gyrase and DNA topoisomerase IV. Quinolones are shown to stabilize the ternary quinolone-gyrase-DNA complex and inhibit the religation of the cleaved double-stranded DNA. Bacteria can acquire resistance to quinolones by mutations of these target enzymes. Mutation sites and amino acid changes in DNA gyrase and DNA topoisomerase IV are similar in the organisms examined, suggesting that the mechanism of quinolone resistance in the target enzymes is essentially the same among various organisms. Quinolones act on both the target enzymes to different degrees depending on the organisms or agents tested, and bacteria become highly resistant to quinolones in a step-wise fashion. Incomplete cross-resistance among quinolones in some strains of E. coli and S. aureus suggests the possibility of finding quinolones active against quinolone-resistant strains which are prevailing now. To find such quinolones, the potency toward two target enzymes and the membrane permeability including influx and/or efflux systems should be taken into account.

• Biomedical Science Letters
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• v.7 no.3
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• pp.117-125
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• 2001

This study was performed in order to evaluate the risk factors for nosocomial urinary tract infection and the frequencies of organisms isolated, and to provide the epidemiologic and basic data of hospital acquired urinary tract infection in intensive care unit. A prospective analysis was performed with 1,235 urine samples following urinary bladder catheterization in 569 patients, who had no evidence of UTI at the time of catheter insertion, admitted to intensive care unit in Pusan P hospital between June 1997 and May 1998. To identify risk factors for UTI, clinical characteristics of infected patients were analyzed. We analyzed these data by percentage, chi-square and odd ratio. Obtained results were as follows: A total of 569 patients (male 341 and female 228) were an average age of 50.8 years and catheterization of 8.04 days. Incidence of UTI was 16.1% (199/1,235) and The risk factors of UTI were duration of catheterization over 7 days, no use of systemic antibiotics, summer and female, and During the first 7 days these risk factors were no use of systemic antibiotics, summer, place of first catheter insertion (ICU) and type of intensive care unit (NSICU). A total of 220 the isolated strains were Gram negative rod 83 (37.7%), yeast like fungi 74 (33.6%) and Gram positive cocci 63 (28.6%). The common organisms isolated were Enterococcus faecalis 23 (10.5%), Serratia marcescens 19 (8.6%), Pseudomonu spp.17 (7.7%), E. ooh 16 (7.3%), Staphylococcus epidemidis 11 (5.0%) mdklebsiellapneumoniae 8 (3.6%). Therefore, in these results 199 of 569 (35%) patients in ICU with indwelling urinary catheter developed UTI. The risk factors for UTI are prolonged duration of catheterization, no use of systemic antibiotics, summer, and female.

• Restorative Dentistry and Endodontics
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• v.23 no.2
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• pp.550-560
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• 1998

Prevotella intermedia has been known as one of the important bacterial species involved in the endodontic infections and various periodontal diseases. Polyphosphate has been widely used to prevent decomposition of food and known to have an inhibitory effect on the growth of gram positive bacteria. The purpose of this study was to evaluate the effect of poly phosphate on the growth of Prevotella intermedia, a gram negative bacterium. Prevotella intermedia G8GK3(ATCC 49046) was grown in the presence of polyphosphates with different chain lengths. Inhibitory effect of each polyphosphate, which was added at the beginning or at the early exponential growth phase of Prevotella intermedia, was determined by measuring optical density of the bacterial cells at 540nm, viable cells and lysis of Prevotella intermedia. The results from this study were as follows : 1. Poly phosphate inhibited the growth of Prevotella intermedia. 2. The minimum inhibitory concentration(MIC) of poly phosphate appeared to be 0.05%. 3. Polyphosphates with chain lengths of 5 and 65 demonstrated the greatest inhibitory effect on the growth of Prevotella intermedia. 4. Polyphosphate was bactericidal to Prevotella intermedia, demonstrating the growth inhibition of the bacterium. 5. Polyphosphate induced lysis of Prevotella intermedia. The overall results suggest that polyphosphate has a bactericidal effect on Prevotella intermedia, causing the lysis of the bacterium.

• Restorative Dentistry and Endodontics
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• v.24 no.3
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• pp.447-452
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• 1999

The role of bacteria in root canals and periapical infections is well known and established. In these bacteria, black-pigmented bacteria(BPH) play important role in endodontic infection. BPB are Gram negative anaerobic rods which are closely related 50 clinical symptoms such as pain, percussion, tenderness, foul odor, etc. In America and Europe, many studies on BPB have been done and are continued. But, relatively few studies have been done in Korea, especially its prevalence in Korean population is not yet studied. The purpose of this study is to establish prevalence of BPB in infected root canals and periapical abscesses in Korean people. Microbial samples were collected from the root canals of 34 intact tooth with periapical rarefactions of endodontic origin and 3 periapical abscesses. All samples were incubated in an anaerobic chamber(Coy, Model No. 77. Ann Arbor, Michigan, USA.). Identification of In microorganism was based on its growth in the anaerobic chamber, colonial pigmentation, colonial morphology, Gram stain, and Rapid ID32A(BioMericux SA/69280 Marcy-l'Etoile/France) results. In addition, the polyme ase chain reaction using specific primers for 16S rRNA genes were used differentiate Prevotella nigrescens for Prevotella intermedia. The results were as follows : 1. In this study, thirteen (35%) of thirty seven samples were positive for the growth of BPB. In thirteen samples, sixteen strains of BPR were found. 2. The most frequently identified BPB in root canals and abscesses in Korean were P. nigrescens 5/37(14%) and P. intermedia 5/37(14%). Porphyromonas gingivalis 3/37(8%), Porphyromonas endodontalis 2/37(5%) and Prevotella loecheii 1/37(3%) were also found. 3. In this study, no significant differences were found between the prevalence of BPB in Korean and that of American and European.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.51 no.4
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• pp.389-396
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• 2018

Marine pathogenic bacteria, such as Streptococcus parauberis, Edwardsiella tarda and Vibrio harveyi, can cause lethal infections in farmed fish, ozone and antibiotics, are employed to sterilize waters used for rearing fish to mitigate this threat. The most widely used method is treatment with sodium hypochlorite solution. However, the maintenance of a constant concentration of chlorine in rearing waters can be difficult. We investigated the potential of a mixed oxidant (MO) solution generated by electrolysis of sea water to improve water quality. We measured the survival rates of fish pathogenic bacteria exposed to different concentrations of MO (0.5, 1.0, 1.5 and 2.0 MO) and sodium hypochlorite (0.5, 1.0, 1.5 and 2.0 ppm) for various lengths of time (0, 5, 10, 15, 20, 25 and 30 min). We found a time-dependent decrease in the survival rates of the tested pathogenic microorganisms. The sterilization effect of the MO solution on pathogenic organisms was greater than that of sodium hypochlorite for gram-negative and gram-positive bacteria. We conclude that MO solution produced by electrolysis could be used to maintain a constant chlorine concentration in aquaculture systems.

• The Korea Journal of Herbology
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• v.33 no.4
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• pp.35-41
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• 2018

Objectives : Hyeonggaeyeongyotang Gagambang (HYT) is a herbal medicine prescribed for the treatment of inflammatory diseases, but it is necessary to study the exact therapeutic efficacy. This study aims to investigate the antibacterial and anti-inflmmatory activities of HYT. Methods : Antibacterial activity of HYT was confirmed by staining Escherichia coli, a gram negative strain, and Staphylococcus aureus, a gram positive strain, on solid Lysogeny Broth (LB) medium containing HYT. Antioxidant activity of HYT was confirmed by 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid (ABTS) assay. The phosphorylation of nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor, alpha ($I{\kappa}B{\alpha}$) after lipopolysaccharide (LPS) treatment with HYT-treated RAW 264.7 mouse macrophages cells was confirmed by immunoblot analysis and the level of interleukin 1 beta (IL-$1{\beta}$) mRNA expression level was confirmed by quantitative real-time PCR. Results : HYT showed a concentration-dependent antibacterial activity against Escherichia coli and Staphylococcus aureus and also showed excellent antioxidant activity. HYT treatment attenuated the phosphorylation of $I{\kappa}B{\alpha}$induced by LPS treatment in RAW 264.7 mouse macrophages cells. The phosphorylation of $I{\kappa}B{\alpha}$is crucial for the regulation of the expression of various pro-inflammatory cytokines. In addition, IL-$1{\beta}$ mRNA expression level of RAW 264.7 mouse macrophages cells stimulated by LPS treatment was also inhibited by HYT treatment. Conclusions : Through experimental demonstration of the antioxidative, antimicrobial and anti-inflammatory effects of HYT, we demonstrated that HYT is a herbal medicine effective for the treatment of inflammatory diseases caused by various bacterial infections.