• Genomics & Informatics
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• 제15권4호
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• pp.136-141
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• 2017

Accurate detection of genomic alterations, especially druggable hotspot mutations in tumors, has become an essential part of precision medicine. With targeted sequencing, we can obtain deeper coverage of reads and handle data more easily with a relatively lower cost and less time than whole-exome or whole-genome sequencing. Recently, we designed a customized gene panel for targeted sequencing of major solid cancers. In this study, we aimed to validate its performance. The cancer panel targets 95 cancer-related genes. In terms of the limit of detection, more than 86% of target mutations with a mutant allele frequency (MAF) <1% can be identified, and any mutation with >3% MAF can be detected. When we applied this system for the analysis of Acrometrix Oncology Hotspot Control DNA, which contains more than 500 COSMIC mutations across 53 genes, 99% of the expected mutations were robustly detected. We also confirmed the high reproducibility of the detection of mutations in multiple independent analyses. When we explored copy number alterations (CNAs), the expected CNAs were successfully detected, and this result was confirmed by target-specific genomic quantitative polymerase chain reaction. Taken together, these results support the reliability and accuracy of our cancer panel in detecting mutations. This panel could be useful for key mutation profiling research in solid tumors and clinical translation.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2005년도 생물공학의 동향(XVI)
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• pp.19-19
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• 2005

This paper reports a novel magnetic force-based microfluidic immunoassay using microbeads and magnetic nanoparticles. The magnetic force-based immunoassay was devised first and successfully applied to detect the rabbit IgG as the model analyte of microfluidic sandwich immunoassay. The microchannels were fabricated by poly(dimethysiloxane) (PDMS) molding processes and bonded on a slide glass by plasma treatment. At the part of the inlet, sample solution was hydrodynamically focused. The focused microbeads of sample solution were flowed through the 150 ${\mu}m$ width channel of outlet. However, when the microbeads are conjugated with the superparamagnetic nanoparticles under the applied magnetic fields, they will switch their flow path and flow through the 95 ${\mu}m$ width channel of outlet. The movements of microbeads conjugated with magnetic nanoparticles were demonstrated by magnetic field $gradients.^{1)}$ High magnetic field gradients using micro electromagnets could be applied to this detection method for high sensitivity and lower detection limit. In addition, the multiplexed $immunoassay^{2)}$ using an encoded microbead which is immobilized with a certain antibody could be possible using this detection principle.

• Journal of Applied Biological Chemistry
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• 제49권4호
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• pp.143-147
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• 2006

A rapid PCR-based assay for detecting hepatitis B viral DNA(HBV DNA) in serum and plasma was developed using a new PCR instrument named GenSpector(TMC-1000, Samsung electronics). PCR was carried out using a chip-based platform, which enabled 50 PCR cycles with internal controls, and melting-curve analysis in 30 minutes. Verification of the amplified HBV DNA product and the internal control was based on specific melting temperatures(Tm) analysis, executed by the GenSpector software. Primers were designed within the region conserved through HBV genotypes A to F. The lower limit of detection was 840 copies/ml serum, conducted with serial dilutions of a HBV DNA positive control(ACCURUN 325 series 700, Boston Biomedica Inc.). The assay was also compared to another assay for HBV DNA(Versant HBV DNA 3.0 assay, Bayer HealthCare) for 200 samples(each 100 clinical negative and positive samples). The sensitivity and specificity were 100% matched. This rapid PCR-based assay is specific, reproducible, and enables qualitative detection of HBV DNA.

• 제어로봇시스템학회논문지
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• 제18권11호
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• pp.997-1004
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• 2012

In enterprise software projects, performance issues have become more critical during recent decades. While developing software products, many performance tests are executed in the earlier development phase against the newly added code pieces to detect possible performance regressions. In our previous research, we introduced the framework to enable automated performance anomaly detection and reduce the analysis overhead for identifying the root causes, and showed Statistical Process Control (SPC) can be successfully applied to anomaly detection. In this paper, we explain the special performance trend in which the existing anomaly detection system can hardly detect the noticeable performance change especially when a performance regression is introduced and recovered again a while later. Within the fixed number of sampling period, the fluctuation gets aggravated and the lower and upper control limit get relaxed so that sometimes the existing system hardly detect the noticeable performance change. To resolve the issue, we apply dynamically tuned sampling window size based on the performance trend, and Fuzzy theory to find an appropriate size of the moving window.

• Bulletin of the Korean Chemical Society
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• 제27권2호
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• pp.277-280
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• 2006

Rapid and highly sensitive determination of nicotine in a PDMS microfluidic channel was investigated using surface enhanced Raman spectroscopy (SERS). A three-dimensional PDMS microfluidic channel was fabricated for this purpose. This channel shows a high mixing efficiency because the transverse and vertical dispersions of the fluid occur simultaneously through the upper and lower zig zag-type blocks. A higher efficiency of mixing could also be obtained by splitting each of the confluent streams into two sub-streams that then joined and recombined. The SERS signal was measured after nicotine molecules were effectively adsorbed onto silver nanoparticles by passing through the three-dimensional channel. A quantitative analysis of nicotine was performed based on the measured peak area at 1030 $cm^{-1}$. The detection limit was estimated to be below 0.1 ppm. In this work, the SERS detection, in combination with a PDMS microfluidic channel, has been applied to the quantitative analysis of nicotine in aqueous solution. Compared to the other conventional analytical methods, the detection sensitivity was enhanced up to several orders of magnitude.

• Journal of Microbiology and Biotechnology
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• 제33권8호
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• pp.1101-1110
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• 2023

Streptococcus mutans is the primary causative agent of caries, which is one of the most common human diseases. Thus, rapid and early detection of cariogenic bacteria is critical for its prevention. This study investigated the combination of loop-mediated isothermal amplification (LAMP) and microfluid technology to quantitatively detect S. mutans. A low-cost, rapid microfluidic chip using LAMP technology was developed to amplify and detect bacteria at 2.2-2.2 × 10⁶ colony-forming units (CFU)/ml and its detection limits were compared to those of standard polymerase chain reaction. A visualization system was established to quantitatively determine the experimental results, and a functional relationship between the bacterial concentration and quantitative results was established. The detection limit of S. mutans using this microfluidic chip was 2.2 CFU/ml, which was lower than that of the standard approach. After quantification, the experimental results showed a good linear relationship with the concentration of S. mutans, thereby confirming the effectiveness and accuracy of the custom-made integrated LAMP microfluidic system for the detection of S. mutans. The microfluidic system described herein may represent a promising simple detection method for the specific and rapid testing of individuals at risk of caries.

• 한국환경보건학회지
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• 제44권5호
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• pp.491-501
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• 2018

Objectives: The aims of this study were to compare concentrations and the correspondence of human blood cadmium by using graphite furnace atomic absorption spectrometry (GF-AAS) and inductively coupled plasma-mass spectrometry (ICP-MS), which are representative methods of heavy metal analysis. Methods: We randomly selected 79 people who agreed to participate in the research project. After confirming the linearity of the calibration curves for GF-AAS and ICP-MS, the concentrations of cadmium in a quality control standard material and blood samples were measured, and the correlation and the degree of agreement were compared. Results: The detection limit of ICP-MS (IDL: $0.000{\mu}g/L$, MDL: $0.06{\mu}g/L$) was lower than that of GF-AAS (IDL: $0.085{\mu}g/L$, MDL: $0.327{\mu}g/L$). The coefficient of variation of the quality control standard material showed stable values for both ICP-MS (clinchek-1: 5.35%, clinchek-2: 6.22%) and GF-AAS (clinchek-1: 7.92%, clinchek-2: 5.22%). Recovery was relatively high for both ICP-MS (clinchek-1: 95.1%, clinchek-2: 92.8%) and GF-AAS (clinchek-1: 91.4%, clinchek-2: 98.8%), with more than 90%. The geometric mean, median, and percentile of blood samples were all similar. The agreement of the two instruments compared with the bias of the analytical values found that about 81% of the analytical values were within ${\pm}30%$ of the deviation from the ideal reference line (y=0). As a result of the agreement limit, the value included in the confidence interval was about 94%, which shows high agreement. Conclusion: In this study, we confirmed there was no significant difference in concentrations of a quality control standard material and blood samples. Since ICP-MS showed lower concentrations than GF-AAS at concentrations below the method detection limit of GF-AAS, it is expected that more precise results will be obtained by analyzing blood cadmium with ICP-MS.

• 한국포장학회지
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• 제14권1호
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• pp.35-42
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• 2008

국내에서 유통 중인 NY/PE 또는 NY/LLDPE, PETP/PE와 PVDC 재질의 총 28가지 식품용 공기차단성 합성수지 필름들을 수집하여 증발잔류물(총이행량), 항산화제, 과망간산칼륨소비량, 중금속, 그리고 가소제에 대한 재질실험과/또는 용출실험을 함으로써 이들 포장재들이 국내 기준규격에 적합한지 여부와 안전성 수준을 파악하였다. 지방성식품모사용매로서 n-heptane을 이용하여 측정한 총이행량의 평균값은 NY/PE 또는 NY/LLDPE, PETP/PE와 PVDC에서 각각 7.6, 6.9, 그리고 14.1 mg/L이었다. 이러한 총이행량값은 국내 식품공전에 명시된 PE과 PVDC 재질에 대한 기준치인 150과 30 mg/L와 비교하여 매우 낮은 수준이었다. 조사된 거의 대부분의 포장재 시료들에서 Irganox 1010, Irganox 1076과 Irgafos 168같은 항산화제들이 검출되었다. 특정이행량 실험 결과 PVDC를 제외한 모든 시료들에서 Irganox 1076과 Irgafos 168이 이행된 것으로 확인되었는데 Ny/PE/LLDPE(15/25/50 ${\mu}m$) 시료로 Irganox 1076이 216.9 ${\mu}g/g$ 이행된 것이 가장 높은 값이었던 것으로 확인되었다. 조사된 시료들에서 가소제들은 모두 검출한계 이상으로 확인이 불가능하였으며, 과망간산칼륨소비량은 국내 기준치인 10 mg/L보다 훨씬 낮은 수준이었음이 확인되었다. 조사된 모든 재질내 카드뮴과 납의 함량은 국내 기준치인 100 mg/kg보다 매우 낮은 수준이었고 이행량은 검출한계 이하의 값을 보였다. 국내외 관련 법규에서의 국내 식품용 용기포장재에 대한 안전성과 관련한 재질과 용출실험의 기준치를 감안할 때 모든 차단성 합성수지식품 포장재 시료들은 조사된 항목에 대한 현행 기준 규격에 적합한 것으로 확인되었다.

• 한국잠사곤충학회지
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• 제39권2호
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• pp.154-160
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• 1997

Present experiment designed for the review of theoretical basis for the inspection system of infected insects by Nosema bombycis. A microporidian N. bombycis, known as the high virulence, produced at the average of 7$\times$108 spores per female moth of the silkworm, Bombyx mori, enabled transovarial tranmission. Detectability of N. bombycis spores in the mass inspection was varied by dillution level, the higher limit of dillution with healthy moths was 1:140 for 100% detection, 1:160 for 99.5%, 1:200 for 99.0%. For an efficient inspection under the microscopic observation (600$\times$), the lower limit of spore concentration was determined as 1, 000, 000 spores/ml, 60-80 moths could be applicable for a maximum sample unit of a lot. Following the present inspection unit conditioned 35 to 40 moths for a lot. N. bombycis spores were easily detectable from the preparation of crude homogenate with 2% KOH, even the step of contrifuge was omitted. The results suggested a new basis of rational mass inspection system of silkworm female moths to save the facilities, labor, and time.

• 대한수의학회지
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• 제44권3호
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• pp.367-371
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• 2004

This report describes the determination of ceftiofur residues in milk from treatment of lactating dairy cattle by intramuscular injection of three consecutive daily doses of about 1 mg /kg BW, the recommended label dosing. The separation of ceftiofur was achieved on $C_1_8$ reverse phase column. The mobile phase consisted of 0.1% trifluoracetic acid in water (A) and 0.05% acetic acid in acetonitrile (B) and grediently flowed at the flow rate of 0.4 mL/min. As a result of analysis of blank raw bovine milk samples, matrix interference was not shown. Limit of detection and limit of quantitaion was 0.5 ng/mL and 1 ng/mL, respectively. The values of precision and recovery satisfied the guideline of National Veterinary Research and Quarantine Service (NVRQS, Korea). The mean residual concentration of ceftiofur in milk did not exceed 3.71 ng/mL when ceftiofur was administered intramuscularly to lactating dairy cattle for 3 consecutive days at 1 mg/kg of BW per day. It is much lower than the proposed MRL (100 ng/mL) of ceftiofur in milk.