• Korean Journal of Fisheries and Aquatic Sciences
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• v.19 no.2
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• pp.147-154
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• 1986

Vibriosis has caused severe losses among cultured yellowtail (Seriola quinquerediata) at some cage farms in Korea in recent years. Major object of this study was to investigate the causative organism of the diseased cultured yellowtail. The samples were collected from the aquarium of Fisheries Research & Development Agency during the period from November 1984 to January 1985. The experimental results are summarized as follows ; Among the isolated bacteria from the diseased yellowtail, Vibrio sp. isolated from the kidney was considered to he the causative organism. Tetracycline, chloramphenicol and gentamycin were observed as bacteriostatic agents to the pathogenic strain, but sulfisomezole and sulfisoxasole were not. When the isolated strain was injected intramuscularly to yellowtail, rid sea-bream, rock-bream and common carp, it had virulence at $25^{\circ}C$ to all fish examined but to virulence at $15^{\circ}C$ except for yellowtail.

• Journal of Korean Public Health Nursing
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• v.5 no.2
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• pp.67-75
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• 1991

This study was conducted to evaluate the difference of staphylococcal colonization between lactating mothers and nursery stares. Samples were obtained from the hands and noses of the newborn(admitted to S Univ. hospital's nursery from 1991. 5. 23 to 6. 8), their mothers and nursery staffs. They were cultured, and then the presence/absence of pathogenic staphylococci in them were analyzed by Fisher exact probability test which led to these conclusion of significance as follows: 1. No differences were detected in pathogenic rate of nasal swab culture between breast~fed newborns and formula-fed ones. 2. Delivery type and hospitalization the ones from the brest-fed newborns show high rate of Sta. aureus coa(+). In case of either C-sec delivery or long (more than 4 days) hospitalization, formula-fed ones in case of NSVD or short (less than 3 days) hospitalization. 3. The ones from breast feeding mothers show higher sta. aureus coa(+) than those from nursery staffs, which was of no significance statistically. Considering nursery staffs only, however, the comparison of those with the data in April indicates that the pathogen rate is higher for hand than nose, and Sta aureus coa(+) for hand is far lower in June than in April, which was statistically significant. These results lead us to infer that newborn infection in hospitalization could be largely reduced by maintaining the ordinary hygienes. Such as the handwashing of mothers as well as nursery staffs (directly involved in newborn care) Thus the pre-enterance hand washing of a mother who visits the nursery only for breast feeding (without any other medical responsibility) should be done, like other medical agents, with $0.05\%$ chlorhexidine antiseptics rather than simple soap cleansing; the one 'that is worth emphasizing thoroughly.

• Journal of Forest and Environmental Science
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• v.34 no.5
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• pp.395-404
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• 2018

Since the mass mortality of Quercus mongolica has been first reported in Gyeonggi province at 2004, the disease spread rapidly over Korean peninsula annually. Ambrosia beetle (Platypus koryoensis) was known as the insect vector of oak wilt fungus, Raffaelea quercus-mongolicae, and control methods of the disease had mainly been focused on eradication of insect vector. However, for the efficient management of the disease, combined control methods for both of the pathogenic fungus and insect vector are strongly required. As one of the efforts to suppress the pathogenic fungus, antifungal activities of Streptomyces isolated from oak forest soil were assayed in this study. Optimum culture condition for the selected isolates was also studied, As a result, Streptomyces blastmyceticus cultured in PDB (Potato Dextrose Broth) at $25^{\circ}C$ for 1 week showed the strongest antifungal activity against oak wilt fungus. Mycelial growth inhibition rates (MGIRs) of Streptomyces isolates were compared on culture media supplemented with heated and unheated culture filtrates of S. blastmyceticus. MGIRs on culture media with unheated culture filtrates were generally higher than those on culture media with heated culture filtrates. Antagonistic mechanism to get involved in the inhibition of hyphal growth and spore formation of the pathogen is due to the antifungal metabolites produced by Streptomyces. This study will provide the fundamental information in developing biocontrol agents for the environment-friendly management of oak wilt disease.

• Journal of Physiology & Pathology in Korean Medicine
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• v.16 no.6
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• pp.1184-1189
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• 2002

Allii sativi Bulbus(garlic) have been shown to possess medicinal value, in particular, antimicrobial activity. In this study, we compared the efficacy on some pathogenic bacteria and fungus among several different extracts(water, hexane, ethyl acetate, methanol, chloroform) of Allii sativi Bulbus. Animal pathogenic bacteria and fungus(S. gallinarium: KCTC 2441, S. flexneri: KCTC 2361, E. cloacae: KCTC 2006, K. pneumonia: KCTC 2208, C. albicans: KCTC 1940) were used to test by measurement of minimum inhibitory concentrations(MIC) and disc diffusion. Allii sativi Bulbus were cut and mixed with water at 37℃ about 24 h and filtered, and several different solvents(hexane, chloroform, ethyl acetate, methanol) were respectively added to separate the fraction of each solvent. The antimicrobial(bacteriocidal) and antifungal effect were apparently shown from water extract, hexane and ethyl acetate extract against using strains(Staphylococcus gallinarium, Shigella flexneri, Enterobacter doacae, Klebsiella pneumonia, Candida albicans). Especially, the water extract showed the superior efficacy. And the clear zone size of water extract (11～27 mm) was greater than that of gentamycin, hexane extract and ethyl acetate extract against S. gallinarium. S. flexneri, K. pneumonia and C. albicans. Minimum inhibitory concentrations(MIC) of water extract appeared to around 2.0～7.5 ㎎/㎖ against S. gallinarium, S. flexneri, E. cloacae and K. pneumonia. The greater activity was shown by water extract because the MIC of water extract for C. albicans observed in very low concentration(<1.0 ㎎/㎖) compared to hexane(5.0 ㎎/㎖) and ethyl acetate(10.0 ㎎/㎖). Therefore, these results exhibited that water extract of Allii sativi Bulbus have stronger antimicrobial activity than hexane and ethyl acetate extract, and may be useful as topical medicine of superficial infections causing C. albicans as well as antifungal agents.

• Parasites, Hosts and Diseases
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• v.55 no.3
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• pp.233-238
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• 2017

Pathogenic Naegleria fowleri, Acanthamoeba castellanii, and Acanthamoeba polyphaga, are distributed worldwide. They are causative agents of primary amoebic meningoencephalitis or acanthamoebic keratitis in humans, respectively. Trophozoites encyst in unfavorable environments, such as exhausted food supply and desiccation. Until recently, the method of N. fowleri encystation used solid non-nutrient agar medium supplemented with heat-inactivated Escherichia coli; however, for the amoebic encystment of Acanthamoeba spp., a defined, slightly modified liquid media is used. In this study, in order to generate pure N. fowleri cysts, a liquid encystment medium (buffer 1) modified from Page's amoeba saline was applied for encystation of N. fowleri. N. fowleri cysts were well induced after 24 hr with the above defined liquid encystment medium (buffer 1). This was confirmed by observation of a high expression of differential mRNA of nfa1 and actin genes in trophozoites. Thus, this liquid medium can replace the earlier non-nutrient agar medium for obtaining pure N. fowleri cysts. In addition, for cyst formation of Acanthamoeba spp., buffer 2 (adjusted to pH 9.0) was the more efficient medium. To summarize, these liquid encystment media may be useful for further studies which require axenic and pure amoebic cysts.

• Korean Journal of Poultry Science
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• v.26 no.3
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• pp.149-170
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• 1999

Protozoa of the genus Eimeria are the etiologic agents of avian coccidiosis, the most economically important Parasitic disease for the poultry industry. Coccidia multiply in intestinal epithelial cells of a wide range of hosts, including livestock in addition to poultry. Chemotherapy is extensively used to control coccidiosis. However, development of drug resistance by Eimeria parasites, the intensive cost and labor involved in the identification of new anticoccidial compounds and public awareness of drug residues in foods warrant alternative methods to prevent coccidiocic in the fast growing poultry industry. For these reasons, there is a great interest in developing vaccines against avian coccidiosis. Live Eimeria vaccines confer protective immunity, however a significant disadvantage of using these types of vaccines is their pathogenicity. Live parasites with attenuated pathogenicity also usually produce immunity but may revert back to a pathogenic form and may be contaminated with other pathogenic organisms. Killed Eimeria vaccines are safer but, unlike live attenuated vaccines, are not able to generate cytotoxic T lymphocyte responses. Recombinant vaccines are biochemically purified proteins produced by genetic engineering that consist of particular epitopes or metabolites of Eimeria. Unlike live attenuated organisms, recombinant vaccines do not possess as much risk and generally are able to induce both humoral and cell mediated immunity. DNA vaccines consist of genes encoding immunogenic proteins of pathogens that are directly administered into the host in a manner that the gene is expressed and the resulting protein generates a protective immune response. Although all of these different types of vaccines have been applied to coccidiosis, this disease continues to cause substantial morbidity and mortality in the poultry industry. Future development of an effective vaccine against coccidiosis will depend on further investigation of protective immunity to Eimeria infection and identification of important immundgenic parasite molecules.

• Journal of Veterinary Clinics
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• v.34 no.4
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• pp.261-267
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• 2017

The aim of this study was to investigate the antibacterial properties of chitosan silver nanocomposites (CAgNCs) using pathogenic Vibrio ichthyoenteri as a bacterial model. Results of agar disc diffusion and turbidimetric assays showed that CAgNCs could inhibit the growth of V. ichthyoenteri in concentration dependent manner. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of CAgNCs were 75 and $125{\mu}g/mL$, respectively. Furthermore, CAgNCs treatment induced the reactive oxygen species (ROS) level in V. ichthyoenteri cells in concentration and time dependent manner, suggesting that it generates oxidative stress, leading to bacterial cell death. The field emission scanning electron microscope (FE-SEM) images of CAgNCs treated V. ichthyoenteri exhibited strong cell membrane damage than un-treated control bacteria. MTT assay results showed the highest cell viability (22%) at $75{\mu}g/mL$ of CAgNCs treated bacteria samples. The results from this study suggest that CAgNCs is a potential antibacterial agent to control fish pathogenic bacteria.

• Asian-Australasian Journal of Animal Sciences
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• v.31 no.10
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• pp.1677-1684
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• 2018

Objective: To find biological functions such as antibacterial and antioxidant activities in several tropical plants and to investigate the possibility of antibiotic substitute agents to prevent and treat diseases caused by pathogenic bacteria. Methods: Plants such as Poncirus trifoliata fruit (Makrut), Zingiber officinale Rosc (Khing), Areca catechu L. (Mak), Solanum melongena L. I (Makkhuayao), and Solanum melongena L. II (Makhurapro) were extracted by methanol, n-hexane, chloroform, ethyl acetate, butanol and water. The free radical scavenging activities were measured using 2-diphenyl-2-picryl hydrazyl photometric assay. Antibacterial activities with a minimum inhibitory concentration (MIC) were observed by agar diffusion assay against pathogenic strains of Escherichia coli, Burkholderia sp., Haemopilus somnus, Haemopilus parasuis, Clostridium perfringens, and Pantoea agglomerans. Results: Poncirus trifoliata fruit methanol extract showed antibacterial activities against gram-negative and gram-positive pathogens. Additionally, this showed the strongest antibacterial activity against Burkholderia sp. and Haemopilus somnus with MIC $131{\mu}g/mL$, respectively. Areca catechu L. water extract showed antibacterial activities against Burkholderia sp., Haemopilus somnus, and Haemopilus parasuis. The MIC value for Haemopilus parasuis was $105{\mu}g/mL$ in this. Antioxidant activity of Zingiber officinale Rosc n-hexane extract showed 2.23 mg/mL effective concentration 50% ($EC_{50}$) value was the highest activity among tropical plants extracts. Total polyphenol content in Zingiber officinale Rosc methanol extract was $48.4{\mu}g/mL$ and flavonoid content was $22.1{\mu}g/mL$ showed the highest values among tested plants extracts. Conclusion: Taken together, these results suggest that tropical plants used in this study may have a potential benefit as an alternative antibiotics agent through their antibacterial and antioxidant activities.

• Biomedical Science Letters
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• v.3 no.1
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• pp.49-54
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• 1997

Meanwhile Pityrosporum species as well as Candida species in yeast phase are not pathogenic, Pityrosporum in mycelial phase is pathogenic. Pityrosporum species can be isolated not only from tinea versicolor patients but also from ninety (90) percent of healthy persons. Minimal inhibitory concentration (MIC) of ketoconazole against Pityrosporum spp. was 0.05~0.8$\mu\textrm{g}$ ml$^{-1}$and the MIC of ketoconazole was the lowest. Of itraconazole, selenium sulfide, sodium thiosulfate and ketoconazole had the lowest MIC against P. orbiculare. The P. orbiculare strains isolated from healthy persons were inhibited by lower MIC than those isolated from tinea versicolor patients. P. ovale strains were inhibited by lower MIC at MIC$_{50}$ and MIC$_{90}$ of oral and topical antifungal agents than p. orbiculare.

• The Plant Pathology Journal
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• v.34 no.4
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• pp.269-285
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• 2018

Bacterial leaf blight is a major disease of eucalypt, especially under nursery conditions. Different bacterial species have been associated with the disease in several countries, and despite its importance worldwide, it is not clear to date whether similar disease symptoms are caused by the same or by different etiological agents. In this study, 43 bacterial strains were isolated from blighted eucalypt leaves collected in different geographic areas of Brazil and inoculated onto a susceptible eucalypt clone. Polyphasic taxonomy, including morphological, physiological, biochemical, molecular, and pathogenicity tests showed that only certain strains of Xanthomonas axonopodis caused symptoms of the disease. Strains varied in their aggressiveness, but no correlation with geographic origin was observed. MLSA-based phylogenetic analysis using concatenated dnaK, fyuA, gyrB and rpoD gene sequences allocated the strains in a well-defined clade, corresponding to Rademarker's group RG 9.6. Inoculation of nineteen plant species belonging to seven botanical families with representative strain LPF 602 showed it to be pathogenic only on Eucalyptus spp, and Corymbia spp. Based on distinct biochemical and pathogenic characteristics that differentiate the eucalypt strains from other pathovars of the X. axonopodis species, here we propose their allocation into the new pathovar X. axonopodis pv. eucalyptorum pv. nov.