• The Journal of the Korean Society for Microbiology
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• v.21 no.4
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• pp.487-501
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• 1986

Previous studies from our laboratory suggested that Korean LJP patients might habor A. actinomycetemcomitans of different serotype from Caucasian LJP patients in whom serotype b was predominant. In order to observe the prevalence and serotype distribution of A. actinomycetemcomitans in localized juvenile periodontitis patients and to evaluate leukotoxic activity of oral isolates, this study was performed. A. actinomycetemcomitans was isolated by using a selective medium(tryptic soy agar supplemented with 10% serum, $75{\mu}g$ of bacitracin and $5{\mu}g$ of vancomycin per ml). Using immunoabsorbed, ammonium sulfate-fractionated serotype-specific antisera, a total of 69 strains were serologically categorized by ELISA. Leukotoxicity was monitored biochemically by measuring lactate dehydrogenase indicator of cell viability in culture supernatant of PMNL plus viable A. actinomycetemcomitans mixture. The results were as follows: 1. A. actinomycetemcomitans was detected in 75% of 16 LJP patients, and 71% in the LJP lesions and 6% in the control sites. 2. Presence or absence of A. actinomycetemcomitans in the sampled disease sites has no in fluence on clinical measurements. 3. Three serotypes were approximately equally distributed in overall 9 patients. Three patients harbored 2 different serotypes of A. actinomycetemcomitans in the same disease site or different disease sites. 4. The proportion of leukotoxic oral isolates was 22% of a total of 46 strains and the prevalence was 69% in 13 sampled sites. The same disease site could harbor both leukotoxic and nonleukotoxic strains. 5. Distribution of leukotoxic strains in 3 serotypes were not different.

• Microbiology and Biotechnology Letters
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• v.35 no.3
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• pp.196-202
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• 2007

Mutations in the cystathionine ${\beta}$-synthase (CBS) gene cause homocystinuria, the most frequent inherited disorder in sulfur metabolism. CBS is the unique enzyme using both heme and pyridoxal 5-phosphate (PLP) for activity. Among the reported 140 mutations, one of the most common disease-causing alterations in human CBS is G307S mutation. To investigate the pathogenic mechanism of G307S by spectroscopic methods, we engineered the full length and the truncated G247S mutation of yeast CBS that is corresponding mutation to human G307S. Yeast CBS does not contain heme and thus gives a merit to study the spectroscopic properties. The UV-visible spectra of the purified full length and the truncated G247S yeast CBSs showed the total absence of PLP in the protein. The absence of PLP in G247S mutation was also confirmed by the PLP-cyanide adduct formation experiment, which was conducted by the incubation of the purified enzyme with KCN. The adducts were detected using a circular dichroism (CD) and a spectrofluorimeter. Radio isotope activity assay of full length and truncated G247S proteins also gave no activity. Our yeast G247S mutation data suggested that G307S might make the distortion of the active site so that cofactor PLP and substrate can not fit inside the active site. Our yeast CBS study addressed the reason why the G307S mutation in human CBS makes the enzyme inactive that consequently leads to severe clinical phenotype.

• Microbiology and Biotechnology Letters
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• v.35 no.2
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• pp.158-162
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• 2007

Methicillin-resistant Staphylococcus aureus (MRSA) is one of a major nosocomial pathogen worldwide and the emergence of this strain has become a major clinical problem. This study was performed for 13 hospitals with more than 400 beds in the country by collecting samples including hands and nasal cavities of doctors, nurses, guardians and patients. Also, additional 320 samples of hands and nasal cavities of 160 community resident in different locations and regions were collected. In all of medical environments and community resident, 625 strains of S. aureus were detected. Among 625 strains of S. aureus, 585 strains(93.6%) showed the resistance to at least one kind of antimicrobial and 112 strains (17.9%) showed multi-drug resistance with the resistance to 4 different types of antimicrobial. Total 152 MRSA strains (24.3%) were isolated from medical environment and community resident. In nasal cavity and hand, 49 MRSA (19.4%) and 103 (27.6%) MRSA were isolated, respectively Minimum inhibitory concentration(MIC) test is used to measure for susceptibility of MRSA isolated to oxacillin. At a concentration $16{\mu}g/ml$ of oxacillin, 11 strains were inhibited. 32 strains at $32{\mu}g/ml$, 41 strains at $64{\mu}g/ml$, 3 strains at $128{\mu}g/ml$, 25 stains at $256{\mu}g/ml$ and 40 strains at over $256{\mu}g/ml$ were inhibited. It was considered that medical environment showed higher than livestock and marine environments in MRSA detection rate.

• Korean Journal of Veterinary Service
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• v.38 no.3
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• pp.145-153
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• 2015

In this study, we developed a loop-mediated isothermal amplification (LAMP) with hydroxynaphtol blue dye (HNB) for rapid and direct visual detection of porcine circovirus 2 DNA with high sensitivity and specificity. The LAMP was completed in 40 min at $63^{\circ}C$, and the results of the LAMP can be confirmed by naked eye without any detection process. The sensitivity of the LAMP was 10-fold higher than that of the commercial PCR (cPCR) and real time PCR (rPCR) previously reported. In clinical application, the PCV2 detection rate of the LAMP was the same on porcine tissue samples (75.0%, 36/48) between porcine blood samples (75.0%, 39/52). The PCV2 detection rate (75.0%) of LAMP was higher than those of the cPCR and rPCR (67.3%, 35/52) in blood samples. In conclusion, the LAMP developed in the study could be an useful alternative method for the detection of PCV2 in the swine disease diagnostic laboratories.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.4
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• pp.2657-2662
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• 2013

Background: Intraoperative sentinel lymph node biopsy has now become the standard of care for patients with clinically node negative breast cancer for diagnosis and also in order to determine the need for immediate axillary clearance. Several large scale studies confirmed the diagnostic reliability of this method. However, micrometastases are frequently missed on frozen sections. Recent studies showed that both disease free interval and overall survival are significantly affected by the presence of micrometastatic disease. The aim of this study was to determine the sensitivity and specificity of intraoperative frozen section analysis of sentinel lymph nodes (SLNs) for the detection of breast cancer micrometastasis and to evaluate the status of non-sentinel lymph nodes (non-SLNs) in those patients subjected to further axillary sampling. Materials and Methods: We performed a retrospective study on 154 patients who underwent SLN biopsy from January 2008 till October 2011. The SLNs were sectioned at 2 mm intervals and submitted entirely for frozen sections. Three levels of each section submitted are examined and the results were compared with further levels on paraffin sections. Results: Overall 40% of patients (62/154) were found to be SLN positive on final (paraffin section) histology, out of which 44 demonstrated macrometastases (>2mm) and 18 micrometastases (<2mm). The overall sensitivity and specificity of frozen section analysis of SLN for the detection of macrometastasis was found to be 100% while those for micrometastasis were 33.3% and 100%, respectively. Moreover 20% of patients who had micrometastases in SLN had positive non-SLNs on final histology. Conclusions: Frozen section analysis of SLNs lacks sufficient accuracy to rule out micrometastasis by current protocols. Therefore these need to be revised in order to pick up micrometastasis which appears to have clinical significance. We suggest that this can be achieved by examining more step sections of blocks.

• Journal of the korean academy of Pediatric Dentistry
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• v.45 no.1
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• pp.32-40
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• 2018

The aim of this study was to determine the efficacy of a 3 tone plaque disclosing gel in assessing the risk of caries related to the population of Streptococcus mutans, Streptococcus sobrinus, and Lactobacillus spp. quantified using a quantitative real-time polymerase chain reaction (qRT-PCR). 15 healthy children of ages 9 - 12 years were randomly examined. The 3 tone plaque disclosing gel was applied on teeth surfaces, which changed the color to pink or red, blue or purple and light blue. Plaque was divided into 3 groups based on staining. Genomic DNA from each sample was subjected to a qRT-PCR assay for quantitative detection of target bacteria. The Kruskal-Wallis test was conducted for correlation between the color of plaque and the number of bacterial species. The levels of S. mutans, S. sobrinus, and Lactobacillus spp. were significantly different in the plaque samples of the 3 groups (p < 0.05). The proportion of S. sobrinus to S. mutans showed correlation to the color of plaque. The different color-dyed plaque was related to the number of acidogenic bacteria. The 3 tone plaque disclosing gel could be used as one of the indicators to assess the clinical risk of caries associated with the population of S. mutans, S. sobrinus, and Lactobacillus spp.

• Journal of Preventive Medicine and Public Health
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• v.32 no.3
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• pp.269-275
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• 1999

Background : In April 6, 1990, a male researcher who has worked at a research unit at the Basic Research Building of Seoul National University(SNU) College of Medicine admitted to SNU Hospital due to persistent fever. He was diagnosed serologically as hemorrhagic fever with renal syndrome(HFRS). Another female researcher in the same unit was also diagnosed as HFRS at the same hospital several days later. Epidemic investigation of HFRS was conducted to determine the magnitude of the problems since these two cases were strongly suspected to have laboratory-acquired infections of HFRS. Methods : All researchers and employees working at the Basic Research Building(BRB) of SNU College of Medicine as of April 1, 1996 were recruited for the study, information on symptoms of HFRS and history of contact to experimental animals were collected by self-administered questionnaires and serological tests among study subjects were also conducted by indirect immunofluorescent antibody(IFA) to hantavirus. The experimental animals were also serologically tested for infection with hantavirus by IFA. Results : Among 218 surveyed, six researchers and an animal caretaker had hantavirus antibodies above 1:20 in IFA titer. Five of seven sero-positive subjects had antibodies above 1:640 in IFA titer and had shown clinical symptoms compatible to HFRS during Jan. 1 to Apr, 20, 1996. The sero-positive persons had handled animals more frequently than sero-negative persons (OR, 19,68; 95% Cl, 1.11-350.40) and handling animals at the animal quarter at School of Public Health(SPH) had shown consistently higher risk to get infected with hantavirus irrespective of types of animals handled (OR, 4.90-6.37). Sero-positivity of rats of the aniamal quarter at BRB was 30-60%, whereas 80% of rats at SPH tested were shown sero-positivity. Conclusion: There was a epidemic of HFRS in research units of a medical school during the period from Jan. through Apr, Further investigation is needed to determine the extent and the mode of transmission of the laboratory-acquired infection with hantavirus in other research facilities.

• Korean Journal of Microbiology
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• v.43 no.1
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• pp.47-53
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• 2007

The DY1 strain of Gram-positive, rod-shaped bacteria was isolated from the soil sample collected from Daeam mountain, Korea. The culture filtrate of DY1 strain showed a broad spectrum of antimicrobial activity on various pathogenic and food poisoning enteric bacterial species tested in vitro. It showed significant growth-inhibitory effect on Salmonella enterica sp., Shigella sp., pathogenic Escherichia coli, Vibrio cholerae, Vibrio parahemolyticus, and Yersinia enterocolitica. For the identification of the DY1 strain, morphological, biochemical and molecular phylogenetic approaches were performed. The DY1 strain was found to be a member of the genus Paenibacillus on the basis of morphological and biochemical analyses. The 16S rDNA of DY1 showed the highest pairwise identity with Paenibacillus polymyxa with 99.79% (1,413 bp/1,416 bp). The antimicrobial entity from DY1 looked different from preciously reported ones and seems to have a great potential to be further studied as a candidate of new antibiotics to control multi-drug resistant pathogens.

• Korean Journal of Microbiology
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• v.49 no.1
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• pp.17-23
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• 2013

Candida biofilms are organized microbial communities growing on the surfaces of host tissues or indwelling medical devices, and the biofilms show enhanced resistance against the conventional antifungal agents. The roots of Coptidis chinensis have been widely used for medicinal purposes in East Asia. The present study was aimed to assess the effect of C. chinensis aqueous extract upon preformed biofilms of 10 clinical Candida albicans isolates and the antifungal activities which contribute to inhibit the C. albicans biofilm formation. Its effect on preformed biofilms was judged using XTT [2,3-Bis-(2-Methoxy-4-Nitro-5-Sulfophenyl)-2H-Tetrazolium-5-Carboxanilide)] reduction assay, and metabolic activity of all tested strains was reduced significantly ($57.3{\pm}14.7%$) at $98{\mu}g/ml$ of the C. chinensis extract. The extract damaged the cell membrane of C. albicans which was analyzed by fluorescein diacetate and propidium iodide staining. The anticandidal activity was fungicidal, and the extract obstructed the adhesion of C. albicans biofilms to polystyrene surfaces, arrested C. albicans cells at $G_o/G_1$ as well, and reduced the growth of biofilms or budding yeasts finally. The data suggest that C. chinensis has multiple antifungal effects on target fungi resulting in preventing the formation of biofilms. Therefore, C. chinensis holds great promise for exploring antifungal agents from natural products in treating and eliminating biofilm-associated Candida infection.

• Journal of Applied Biological Chemistry
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• v.53 no.3
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• pp.126-131
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• 2010

In order to maximize the growth of Bifidobacterium lactis BL 740 and soy isoflavone agycones production, we investigated the optimization of a culture medium containing soy hypocotyls, which are the byproducts of the soy manufacturing process, and soy proteins. The ingredients of the medium containing soy materials (S-medium) were selected by fractional factorial design (FFD) and central composite design (CCD) within a desirable range. The FFD was applied by six factors: glucose, cellobiose, fructooligosaccharide, soy peptone, soy protein, and soy hypocotyl. Soy protein, soy peptone, and soy hypocotyl were found to be significant factors from the result of FFD for both the growth of B. lactis BL 740 and aglycone production. The CCD was then applied with three variables found from FFD at five levels each and the optimum values were determined for the three variables: soy peptone, soy protein, and soy hypocotyl. In the case of the growth of B. lactics BL740, the proposed optimal media contained 12.73 g/L of soy protein, 29.55 g/L of soy peptone, and 130.67 g/L of soy hypocotyl. To produce isoflavone aglycones, optimized media was composed of 2.06 g/L, soy protein, 1.25 g/L of soy peptone, and 60.02 g/L of soy hypocotyl.