• 생명과학회지
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• 제26권2호
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• pp.220-225
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• 2016

본 연구는 치과 병의원 진료실 주변환경과 치과종사자의 휴대전화에서 분리된 coagulase-negative staphylococci (CNS)의 분리율과 항균제 내성양상 및 분자 역학적 특성을 분석하고자 하였다. 2014년 12월부터 2015년 1월까지 부산지역 10개의 치과 병의원에서 총 154개의 샘플을 수집하여 MALDI-TOF분석법을 통해 동정하였다. 항균제 감수성검사는 디스크 확산법을 시행하였고 mupA, mecA 유전자 보유현황 및 SCCmec type은 PCR과 염기 서열분석에 의해 결정하였다. 154개의 샘플 중 10개(6.5%)에서 CNS 균주(Staphylococcus epidermidis 5주, Staphylococcus capitis 2주, Staphylococcus warneri 2주, Staphylococcus haemolyticus 1주) 가 분리되었다. 항균제 감수성검사에서 penicillin 10주, mupirocin 6주, gentamicin 5주, tetracycline 3주 및 cefoxitin과 erythromycin 2주가 내성이었고 clindamycin, ciprofloxacin, teicoplanin, trimethoprim-sulfamethoxazole에 내성인 세균은 없었다. 2개의 CNS균주(S. warneri, S. haemlyticus)에서 mecA 유전자가 검출되었고 1개의 CNS균주(S. epidermidis)에서 mupA가 확인되었다. Methicillin 내성 CNS균주 가운데 1주는 SCCmec I형이었고 1균주는 SCCmec의 유전형이 구분되지 않았다. 본 연구를 통하여 다약제 내성을 보이는 CNS균주가 더 이상 우리나라 치과병의원 환경에서 드물지 않음을 알 수 있었다.

• 조명전기설비학회논문지
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• 제27권8호
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• pp.83-89
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• 2013

In this paper, discharge characteristics of air in the vertical arrangement of three rods(dome-shaped, cylinder-shaped, and needle-shaped rod) and plane gap having propane flame on the plane electrode are examined under the application of a.c. and d.c. high-voltages. As the result of the experiment, flashover voltages in the presence of the flame are substantially lowered than those in the absence of flame, and relative a.c. flashover voltages in the dome-shaped, cylinder-shaped, and needle-shaped rod gaps are found 32.5%, 32.1%, and 26.4% respectively. The polarity effects with the d.c. voltages are shown, and flashover voltages in negative polarity are much lowered than those in positive one. The negative flashover voltages in the dome-shaped and cylinder-shaped gaps are found 18.3% and 18.7% respectively, but the positive ones are found 53.5% and 43.2% respectively. In the needle-shaped rod gaps, meanwhile, the flame is extinguished by corona wind, and the quenching voltages are found 28.4% under the application of a.c. voltages. The ion winds of corona and the reduction of air density are the main factors of flashover reduction owing to the flame in the case of a.c. voltages, but the electrifications of the positive ion by thermal ionization besides the above factors are remarkably found in the case of d.c. voltages.

• KSBB Journal
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• 제31권4호
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• pp.263-269
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• 2016

For decades, the microorganisms in arctic soils have been newly discovered according to the climate change and global warming. In this study, the chemical structure of a lipid A molecule from Pseudomonas sp. strain PAMC 28615 which was newly discovered from arctic soils was characterized by mass spectrometric approaches such as matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) and MALDI multi-stage tandem mass spectrometry (MS). First, lipopolysaccharide (LPS) from Pseudomonas sp. strain PAMC 28615 was extracted and subsequently hydrolyzed to obtain the lipid A. The parent ion peak at m/z 1632 was determined by MALDI-TOF MS, which also can validate our lipid A purification method. For detailed structural determination, we performed the multiple-stage tandem mass analysis ($MS^4$) of the parent ion, and subsequently the abundant fragment ions in each MS stage are tested. The fragment ions in each MS stage were produced from the loss of phosphate groups and fatty acyl groups, which could be used to confirm the composition or the position of the lipid A components. Consequently, the mass spectrometry-based lipid A profiling method could provide the detail chemical structure of lipid A from the Pseudomonas sp. strain PAMC 28615 as an arctic bacterium from the frozen arctic soil.

• Mass Spectrometry Letters
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• 제5권1호
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• pp.24-29
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• 2014

An advanced and reliable high performance liquid chromatography (HPLC)/ultraviolet detector (UV)/ion-trap time-of-flight (IT-TOF) mass spectrometry was developed for the simultaneous quantification of 19 marker compounds in Bang-poong-tong-sung-san (BPTS), a traditional oriental prescription. Various parameters affecting HPLC separation and IT-TOF detection were investigated, and optimized conditions were identified. The separation was achieved on a Capcell PAK C18 column ($1.5mm{\times}250mm$, $5{\mu}m$ particle size) using a gradient elution of acetonitrile and water containing 0.1% formic acid at a flow rate of 0.1 mL/min. The column temperature was maintained at $40^{\circ}C$ and the injection volume was $2{\mu}L$. IT-TOF system was equipped with an electrospray ion source (ESI) operating in positive or negative ion mode. The optimized electrospray ionization parameters were as follows: ion spray voltage, +4.5 kV (positive ion mode), or -3.5 kV (negative ion mode); drying gas ($N_2$), 1.5 L/min; heat block temperature, $200^{\circ}C$. Automatic $MS^n$ (n = 1~3) analyses were carried out to obtain structural information of analytes. Elemental compositions and their mass errors were calculated based on their accurate masses obtained from a formula predictor software. The marker compounds in BPTS were identified by comparisons between $MS^n$ spectra from standards and those from extracts. Moreover, the libraries of $MS^2$ and $MS^3$ spectra and accurate masses of parent and fragment ions for marker compounds were constructed. The developed method was successfully applied to the BPTS extracts and identified 17 out of 19 marker compounds in the BPTS extracts.

• Journal of Plant Biotechnology
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• 제5권3호
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• pp.181-185
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• 2003

Callus and suspension cultures derived from leaf explants of Plumbago rosea were established on Murashige and Skoog's medium containing 1 mg/L IAA, 0.5 mg/L NAA and 0.3 mg/L BAP. Callus cultures were tested for their growth and accumulation of plumbagin, a naphthoquinone and was identified by $^1H$ NMR and electron ionization mass spectroscopy. While auxins (not 2,4-D) influenced growth and plumbagin accumulation, cytokinins did not influence them much. Increasing concentrations of IAA in presence of NAA and BAP increased plumbagin in suspensions only up to 1 mg/L. Growth of callus was optimum (8.3 g DCW/I) at a hormonal combination of 1.5 mg/L IAA, 0.5 mg/L NAA and 0.3 mg/L BAP, but high plumbagin accumulation (4.9 mg/g DCW) was recorded at 1.0 mg/L IAA plus 0.3 mg/L BAP. Since instability in growth and secondary metabolite accumulation was noticed, several cell lines/clumps of callus were screened for plumbagin accumulation by visual and analytical methods. Biomass and accumulation of plumbagin showed a negative correlation in several cell lines. But one cell line showed stability both in terms of biomass and plumbagin accumulation over a period of 6 months.

• Bulletin of the Korean Chemical Society
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• 제31권2호
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• pp.275-280
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• 2010

Actinobacillus actinomycetemcomitans is a gram-negative, nonmotile coccobacillus bacterium that is associated with several human diseases, including endocarditis, meningitis, osteomyelitis, subcutaneous abscesses and periodontal diseases. A full-length Omp1-like protein gene from A. actinomycetemcomitans was cloned into a pQE30 vector and overexpressed in Escherichia coli BL21(DE3) cells. The protein revealed sequence homologies to Seventeen kilodalton proteins (Skp) from Pasteurella multocida and E. coli that have been characterized as periplasmic chaperones. This soluble Omp1-like protein was successfully purified to homogeneity for further folding and functional studies. The purity, identity, and conformation of the protein were determined using sodium dodecyl sulfate polyacrylamide gel electrophoresis, matrix-assisted laser desorption ionization mass spectrometry, circular dichroism, fluorescence spectroscopic, and differential scanning calorimetric studies. We showed that the protein formed an oligomer larger than a tetramer. We found, further, that it is comprised of mostly $\alpha$-helices and boasts high thermal stability.

• 한국자기공명학회논문지
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• 제22권2호
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• pp.26-33
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• 2018

Xanthium sibiricum is used as a traditional folk medicine for the treatment of cancer, fever, headache, nasal sinusitis, and skin pruritus. This study aimed to identify components from Xanthium sibiricum extracts using an SPE-800MHz NMR-MS hyphenated system. The simultaneous acquisition of MS and NMR spectra from the same chromatographic peaks significantly increases the depth of information acquired for the compound and allows the elucidation of structures that would not be possible using MS or NMR data alone. LC -NMR analysis was conducted using a HPLC separation system coupled to 800 MHz spectrometer equipped with a cryoprobe, and a SPE unit was used to automatically trap chromatographic peaks using a HPLC pump. LC-MS analysis was conducted with a Q-TOF MS instrument using ESI ionization in the negative ion mode. Using the hyphenated analysis, several secondary metabolites were identified, such as 3',5'-O-dicaffeoylquinic acid, 1',5'-O-dicaffeoyl- quinic acid, and ethyl caffeate. These results demonstrate that the SPE-800MHz NMR-MS hyphenated system can be used to identify metabolites within natural products that have complex mixtures.

• Mass Spectrometry Letters
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• 제6권1호
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• pp.7-12
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• 2015

In the present study, we proposed a simple ESI-MS model for determining $Zn^{2+}$ binding (or dissociation) constants for zinc finger peptides (ZFPs) with a unique ${\beta}{\beta}{\alpha}$ fold consensus. The ionization efficiency (response) factors for this model, i.e., ${\alpha}$ and ${\beta}$, could be determined for ZiCo ZFP with a known $Zn^{2+}$ binding constant. We could determine the binding constants for other ZFPs assuming those with a ${\beta}{\beta}{\alpha}$ consensus conformation have the same ${\alpha}/{\beta}$ response ratio. In general, the ZPF dissociation constants exhibited $K_d$ values of $10^{-7}{\sim}10^{-9}M$, while $K_d$ values for a negative control non-specific $Zn^{2+}$ peptides were high, e.g., $5.5{\times}10^{-6}M$ and $4.3{\times}10^{-4}M$ for BBA1 and melittin, respectively.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제52권4호
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• pp.179-184
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• 2003

The pulsed power system is widely used for many industries and environments. Generally, we call the "RUST", the reddish brown surface, that was made on iron surface or some other metals, when they are contacted by water and air the main substance of rust is oxide-ionization. In other words, the chemical symbol of rust on iron surface is iron oxide(III) hydrate Fe203.nH2O. In this study, we have designed and fabricated our system which has a compact pulse generator with switching MOSFET. Also we have studied the metal-oxide removing characteristics using in the atmospheric arc discharge. It has been investigated their removing characteristics by the change of charging voltage and pulse repetition rates. From this result, we can find out that the removal area Is increased from 3.80 to 8.04[$\textrm{cm}^2$], when pulse duration is increased from 100[pps] to 400[pps]. 400[pps].

• Toxicological Research
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• 제29권2호
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• pp.107-114
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• 2013

Mass spectrometry (MS) is a very powerful instrument that can be used to analyze a wide range of materials such as proteins, peptides, DNA, drugs, and polymers. The process typically involves either chemical or electron (impact) ionization of the analyte. The resulting charged species or fragment is subsequently identified by the detector. Usually, single mass uses source-induced dissociation (SID), whereas mass/mass uses collision-induced dissociation (CID) to analyze the chemical fragmentations Each technique has its own advantages and disadvantages. While CID is most effective for the analysis of pure substances, multiple-step MS is a powerful technique to get structural data. Analysis of veterinary drugs ampicillin, chloramphenicol, ciprofloxacin, and oxytetracycline serves to highlight the slight differences between SID and CID. For example, minor differences were observed between ciprofloxacin and oxytetracycline via SID or CID. However, distinct fragmentation patterns were observed for ampicllin depending on the analysis method. Both SID and CID showed similar fragmentation spectra but different signal intensities for chloramphenicol. There are several factors that can influence the fragmentation spectra, such as the collision energy, major precursor ion, electrospray mode (positive or negative), and sample homogeneity. Therefore, one must select a fragmentation method on an empirical and case-by-case basis.