• Korean Journal of Food Science and Technology
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• v.52 no.3
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• pp.296-303
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• 2020

Hop-resistant lactic acid bacteria (LAB) are well-known, major beer-spoilage bacteria. The hop-gradient agar containing ethanol (c-HGA+E) method has been used to examine hop-resistance of beer-spoilage LAB. However, the selection of beer-spoilage bacteria by the c-HGA+E method is either too selective or too inclusive. Furthermore, it is accompanied by a complicated experimental procedure, high-cost and time. To overcome these disadvantages, the modified hop-gradient agar with ethanol (m-HGA+E) method was developed. The most remarkable modifications were the shape of the petri dish and the inoculation method for bacteria. The efficiency and validation of the m-HGA+E approach were proven by the formation of colonies at different hop concentrations in the bottom layer, co-culture with the bacteriocin producer and by PCR detection of hop-resistant genes. This study demonstrated that m-HGA+E is a rapid, economical, and easy method to monitor potential hop-resistant beer-spoilage LAB during the beer brewing process.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.7
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• pp.515-520
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• 2018

A large number of lithium-ion batteries are arranged in series and parallel in battery packs, such as those in electric vehicles or energy storage systems. As battery packs age, their output power and energy density drop because of voltage deviation, constant and non-uniform exposure to abnormal environments, and increased contact resistance between batteries; this reduces application system efficiency. Despite the balancing circuit and logic of the battery management system, the output of the battery pack is concentrated in the most severely aged unit cell and the output is frequently limited by power derating. In this study, we implemented a cell imbalance detection algorithm and selected parameters to detect a sudden decrease in battery pack output. In addition, we propose a method to increase efficiency by applying the measured testing values considering the operating conditions and abnormal conditions of the battery pack.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.4
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• pp.290-296
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• 2011

Carbon nanotubes (CNTs) have excellent electrical, chemical stability, mechanical and thermal properties. In this paper, networks of Multi-walled carbon nanotube (MWCNT) materials were investigated as a resistive gas sensors for the $H_2$ gas detection. Sensor films were fabricated by the air spray method using the multi-walled CNTs dispersion solution on the glass substrates cured with plasma and nitrocellulose. Sensors were characterized by the resistance measurements in the self-fabricated oven in order to find the optimum detection properties for the hydrogen gas molecular. The sensitivity and the linearity of the MWVNT sensors using the glass substrate cured with plasma for the $H_2$ gas concentration of 0.06~0.6 ppm are 0.013~0.097%/sec and 0.131~0.959%FS, respectively. The MWCNT film was excellent in the response for the hydrogen gas moleculars and its reaction speed was very fast, which could be using as hydrogen gas sensor. The resistance of the fabricated sensors decreases when the sensors are exposed to $H_2$ gas.

• Journal of Microbiology and Biotechnology
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• v.34 no.6
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• pp.1322-1327
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• 2024

The accurate and rapid detection of methicillin-resistant Staphylococcus aureus (MRSA) holds significant clinical importance. This work presents a new method for detecting methicillin-resistant Staphylococcus aureus (S. aureus) in clinical samples. The method uses an aptamer-based colorimetric assay that combines a recognizing probe to identify the target and split DNAzyme to amplify the signal, resulting in a highly sensitive and direct analysis of methicillin-resistance. The identification of the PBP2a protein on the membrane of S. aureus in clinical samples leads to the allosterism of the recognizing probe, and thus provides a template for the proximity ligation of split DNAzyme. The proximity ligation of split DNAzyme forms an intact DNAzyme to identify the loop section in the L probe and generates a nicking site to release the loop sequence ("3" and "4" fragments). The "3" and "4" fragments forms an intact sequence to induce the catalytic hairpin assembly, exposing the G-rich section. The released the G-rich sequence of LR probe induces the formation of G-quadruplex-hemin DNAzyme as a colorimetric signal readout. The absorption intensity demonstrated a strong linear association with the logarithm of the S. aureus concentration across a wide range of 5 orders of magnitude dynamic range under the optimized experimental parameters. The limit of detection was calculated to be 23 CFU/ml and the method showed high selectivity for MRSA.

• The Korean Journal of Pesticide Science
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• v.15 no.1
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• pp.61-67
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• 2011

In 2010, two-spotted spider mite, Tetranychus urticae was collected from the rose greenhouse and apple orchards in Cheongju (CJ), Chungju (CUJ)-1, CUJ-2, Kangjin (KJ), Yesan (YS), and Yeongju (YJ). Among them, KJ and YS strain showed high resistance to bifenazate of 964.5- and 1l30-fold, respectively. The other strains showed low resistance to bifenazate. By analyzing the mitochondrial cytochrome b (cytb) sequence, G126S point mutation was detected in KJ and YS strain. Thus, G126S point mutation in the mitochondrial cytb was available molecular detection marker for selection of bifenazate resistant T. urticae. Two molecular detection methods, quantitative sequencing (QS) and PCR amplification of specific alleles (PASA) were well detected specific G126S point mutation. Therefore, these methods can be used to monitor the resistance allele in field population of T. urticae and bifenazate resistance management strategy.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.7 no.2
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• pp.137-142
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• 2004

Purpose: The resistance of H. pylori to clarithromycin is one of the major causes of eradication failure. In H. pylori, clarithromycin resistance is due to point mutation in 23S rRNA. The aims of this study were to investigate the mutation of 23S rRNA and to examine the association of cagA, vacA genotype and clarithromycin resistant genes. Methods: H. pylori DNA was extracted from antral biopsy specimens from 27 children with H. pylori infection. Specific polymerase chain reaction (PCR) assays were used for cagA and vacA. Mutations associated with clarithromycin resistance were detected by using PCR restriction fragment length polymorphism (RFLP) analysis of 23S rRNA gene. Results: A2143G mutation was detected in one case and A2144G in 4, indicating 18.5% were clarithromycin resistant. Among the total of 27, cagA was present in 25 (93%), vacA s1a/m1 in 6 (22%), s1a/m2 in 3 (11%), s1c/m1 in 16 (59%), and s1c/m2 in 1 (4%). All of the 5 clarithromycin resistant strains were cagA (+), among which 2 were s1a/m1 and 2 were s1c/m1. There was no relation between genotypes and clarithromycin resistant genes. Conclusion: Detection of H. pylori resistance to clarithromycin using PCR RFLP from biopsy specimens might be useful for the selection of antibiotics. Clarithromycin resistant genes are not associated with genotypes of cagA and vacA.

• Korean Journal of Microbiology
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• v.41 no.3
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• pp.177-182
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• 2005

H. pylori strains were isolated from antral biopsies taken during upper endoscopy in 114 dyspeptic patients with no previous therapy against H. pylori. Rapid urease test, PCR amplification of SSA and cagA gene for H. pylori detection, and Western blot for CagA expression detection were performed. H. pylori infected patients were treated with omeprazole, clarithromycin (a macrolide), and amoxicillin. At 6 weeks after the discontinuation of therapy, the bacterial eradication rate was determined by endoscopy. The resistance rate to clarithromycin and amoxicillin was $20.2\%$ and $0.0\%$, respectively. The clarithromycin resistance was mainly caused by the A2142G mutation in the 23S rRNA gene of H. pylori. MICs of clarithromycin for the A2142G mutant isolates were significantly higher than MICs for the A2143G mutant isolates. H. pylori eradication was obtained in all patients with clarithromycin-susceptible isolates but not in patients with clarithromycin-resistant isolates (P = 0.0001). These results did not appear to be biased by any differences in CagA expression. The resistance of H. pylori to clarithromycin included in the therapeutic regimens is the most important reason for treatment failure. H. pylori antimicrobial susceptibility testing of the gastric biopsy culture should be performed before choosing the first triple therapy in infected patients and the increase in prevalence of clarithromycin resistance in Korea was problematic.

• The Journal of the Korean Society for Microbiology
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• v.35 no.2
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• pp.171-180
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• 2000

Ninety two strains of Streptococcus pyogenes were isolated from patients with pharyngitis, scarlet fever, skin infection, and invasive streptococcal infections in Seoul, Korea from January to December, 1998. All isolates were epidemiologically characterized by T protein serotype, and serum opacity factor (OF) detection to phenotypes. To analyze the genetic relationship, fifty two isolates including 32 erythromycin-clindamycin (Em-Cm) resistant strains, 20 antimicrobial susceptible strains were attempted to the pulsed-field gel electrophoresis (PFGE). T protein serotype showed 16 kinds in distribution including T12 and T4. Among the total isolates, 40 strains (43.5%) belonged to the T12 serotype and twenty strains (21.7%) to T4 serotype. On the other hand, when infection aspect of S. pyogenes isolates were analysed by T serotype distribution, T12 type was predominant for pharyngitidis which contributed to 21 strains (53%) and for skin infection isolates which contributed to 11 strains (28%), respectively. In case of T4 type, it was the most predominant pharyngitidis isolates which contributed to 8 strains (40%). In T serotype distribution of Em-Cm resistant strains, 27 strains (84%) of the thirty two showed T12 serotype. In minimum inhibitory concentration (MIC) values of Em-Cm resistance isolates, thirty two isolates showed resistant to erythromycin 27 strains (84%), had high MIC of >$128\;{\mu}g/ml$. And also to clindamycin, twenty two strains (69%) had high MIC of >$128\;{\mu}g/ml$. When OF detection of Em-Cm resistance of S. pyogenes isolates were analyzed by T serotype distribution, T12 serotype isolates revealed that all of the isolates except one strain were OF negative. In PFGE profile analysis to Em-Cm resistance isolates, of the twenty seven, Em-Cm resistance of T12 serotype isolates, 26 strains showed identical PFGE profile and all of these isolates revealed that OF negative. Eighty four percent of Em-Cm resistance S. pyogenes isolates had identical phenotype and PFGE profile. These results strongly suggested that the Em-Cm resistant S. pyogenes isolates from Seoul area showed close genetic correlation and PFGE could be available tool for molecular epidemiology.

• Tuberculosis and Respiratory Diseases
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• v.44 no.5
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• pp.1030-1039
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• 1997

Background : Impulse Oscillometry is a noninvasive and effort-independent test used to characterize the mechanical impedance of the respiratory system. The clinical potential of the IOS is rapid and demands only passive cooperation which makes it especially appealing for children, for epidemiologic surveys and for conditions in which quiet breathig instead of forced expiratory maneuvers are preferred. However, several studies have shown conflicting results that the role of IOS about detection of smoking induced small airway diseases or early airway obstruction Methods : Study was to evaluate the clinical ability of the IOS to detect about smoking induced early airway obstruction in persons with normal spirometry test. Respiratory asymptomatic study groups were formed that one is non-smoking group, another is smoking group. Results : The parameters of spirometry were not significantly differences between non-smoking group and smoking group. Among the parameters of IOS, total resistance(non-smoking group : smoking group=$2.22{\pm}1.20$ : $2.58{\pm}1.71$), peripheral resistance($1.25{\pm}0.62$ : $1.47{\pm}0.10$), bronchial compliance($0.44{\pm}0.12$ : $0.47{\pm}0.16$) were not statistically significant different (p<0.05), but central resistance and lung compliance were not statistically significant different (unit ; resistance=hPa/l/s, compliance=l/hPa). Resistance(Rrs) was not statistically significant different with changes of frequences(5, 10, 15, 20, 25, 30, 35Hz), but Reactance(Xrs) was statistically significant different with low frequences that X5(non-smoking group : smoking group=$-0.62{\pm}0.28$ : $-0.76{\pm}0.48$, p<0.001) and X10($-0.06{\pm}0.19$ : $-0.15{\pm}0.33$, p<0.013) (unit; hPall/s, $hPa{\cong}cmH_2O$). Conclusion : Impulse oocillometer(IOS) is clinically available method to detect about smoking induced early airway obstruction. And clinically potential parameters of IOS were considers that total resistance, peripheral resistance, bronchial resistance, and reactance of low frequency at 5Hz, 10Hz.

• Korean Journal of Clinical Laboratory Science
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• v.43 no.2
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• pp.68-74
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• 2011

Pseudomonas aeruginosa is an aerobic, Gram-negative, glucose-nonfermenting bacterium, which has emerged as a serious opportunistic pathogen. Recently, outbreaks of carbapenem resistant P. aeruginosa give rise to significant therapeutic challenges for treating nosocomial infections. The genes of metallo-${\beta}$-lactamase (MBL), a powerful carbapenemase, are carried as a part of the mobile gene cassettes inserted into integrons playing an important role in rapid dissemination of antibiotic resistance genes among bacterial isolates. In this study, we investigated the prevalence of integron in imipenem resistant P. aeruginosa isolates. A total of 61 consecutive, non-duplicate, and imipenem resistant P. aeruginosa strains were isolated from a university hospital in the Chungcheong province of Korea. We employed repetitive extragenic palindromic sequence-based PCR (rep-PCR) method for the selection of clonally different P. aerusinosa strains. PCR and DNA sequencing were conducted for the detection of integrons. Twenty-one clonally different P. aeruginosa strains were isolated. Only one (P28) of the strains harbored $bla_{VIM-2}$ that was found as gene cassettes in class 1 integrons. Four of 21 carbapenem resistant P. aeruginosa strains harbored class 1 integron containing aminoglycoside resistance determinant. All of the integrons detected in the study contained more than one resistance gene cassette, which can mediate resistance to multiple antibiotics. To prevent further spreading of the multi-drug resistant P. aeruginosa, conseguent monitoring and clinical polices are required.