• 대한의용생체공학회:의공학회지
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• 제35권1호
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• pp.1-7
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• 2014

Among semi-quantitative or fully quantitative lateral flow assay readers, an image sensor-based instrument has been widely used because of its simple setup, cheap sensor price, and compact equipment size. For all previous approaches, monochrome CCD or CMOS cameras were used for lateral flow assay imaging in which the overall intensities of all colors were taken into consideration to estimate the analyte content, although the analyte related color information is only limited to a narrow wavelength range. In the present work, we introduced a color CCD camera as a sensor and a color decomposition method to improve the sensitivity of the quantitative biosensor system which utilizes the lateral flow assay successfully. The proposed setup and image processing method were applied to achieve the quantification of imitatively dispensed particles on the surface of a porous membrane first, and the measurement result was then compared with that using a monochrome CCD. The compensation method was proposed in different illumination conditions. Eventually, the color decomposition method was introduced to the commercially available lateral flow immunochromatographic assay for the diagnosis of myocardial infarction. The measurement sensitivity utilizing the color image sensor is significantly improved since the slopes of the linear curve fit are enhanced from 0.0026 to 0.0040 and from 0.0802 to 0.1141 for myoglobin and creatine kinase (CK)-MB detection, respectively.

• 대한바이러스학회지
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• 제27권2호
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• pp.137-141
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• 1997

We evaluated Immunochromatographic assay kit to screen HBsAg in human serum. When the reference HBsAg was applyed to ICA, HA and EIA kits, the limit of detection for HBsAg were found out to be 4, 2 and 0.25 ng/ml respectively. But ICA kit required 5 minutes to read the result whereas HA and EIA kit more than one hour. The sensitivity was 97% (29 of 30 samples) and the specificity 100% (45 samples) compared with conventional EIA. The ICA kit needs no instrument or machine to perform the test contrary to the conventional methods. Therefore, this rapid and sensitive ICA kit can be used for HBsAg-screening, especially in the emergency room and in the scene of the accident.

• Parasites, Hosts and Diseases
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• 제60권3호
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• pp.201-205
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• 2022

Babesia microti is one of the most common causative agents of babesiosis. A sensitive and rapid detection is necessary for screening potentially infected individuals. In this study, B. microti cytochrome c oxidase subunit I (cox1) was selected as the target gene, multiple primers were designed, and optimized by a recombinase-aided amplification (RAA) assay. The optimal primers and probe were labeled with fluorescein. The sensitivity of fluorescent RAA (fRAA) was evaluated using gradient diluents of the cox1 recombinant plasmid and genomic DNA extracted from whole blood of B. microti infected mice. The specificity of fRAA was assessed by other transfusion transmitted parasites. The analytical sensitivity of the fRAA assay was 10 copies of recombinant plasmid per reaction and 10 fg/µl B. microti genomic DNA. No cross-reaction with any other blood-transmitted parasites was observed. Our results demonstrated that the fRAA assay would be rapid, sensitive, and specific for the detection of B. microti.

• 대한수의학회지
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• 제29권1호
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• pp.21-25
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• 1989

This experiment was carried out to determine the progesterone concentration of bovine plasma by liquid phase double antibody enzyme immunoassay. The optimum conditions of assay-system, enzyme conjugate and gelatin were invested. The sensitivity, recovery rate and reproducibility by this assay were also analyzed. The results obtained were as follows: 1. The suitable supplementation level of gelatin was 0.2%. As the gelatin level increased to 1%, coefficient variation of interassay was shown to be irregular. 2. The optimum dilution rate of enzyme conjugate was 30 times. Enzyme activity was greatly fluctuated depending on the minor condition of enzyme conjugate technique. Therefore, it was considered to be checked when determined. 3. The sensitivity of the assay was 12 pg/tube. 4. Recovery rate was decreased when the amount of sample was too little or too much, but the recovery rate was high as 97.8% when the amount of sample between 50 and $200{\mu}l$. 5. Mean intra-assay and inter-assay coefficient of variation was 4.5% and 5.9%, respectively. By using liquid phase double antibody enzyme immunoassay, progesterone in plasma can be detected, and also this assay system is applicable to study on physiological function of progesterone and to diagnosis of reproductive disorders.

• 한국동물위생학회지
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• 제19권1호
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• pp.30-38
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• 1996

Enzyme-linked immunosorbent assay (ELISA) was developed to detect rotavirus antigen in fecal samples using VP6-specific monoclonal antibody(2B12). The ELISA for rotavirus antigen detection found to have specificity to all bovine and porcine rotaviruses tested but not to bovine viral diarrhea virus and bovine coronavirus. The ELISA appeared to have similar sensitivity and specificity compared to fluorescence antibody assay(FA) and electropherotyping (PAGE).

• Toxicological Research
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• 제24권1호
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• pp.37-44
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• 2008

The in vitro cell transformation assays (CTA) were performed using BALB/3T3 murine fibroblasts and HaCaT human keratinocytes in order to evaluate concordance between both in vitro CTAs and carcinogenicity with compounds differing in their genotoxic and carcinogenic potential. Six test articles were evaluated, two each from three classes of compounds: genotoxic carcinogens (2-amino-5-nitrophenol and 4-nitroquinoline-N-oxide), genotoxic noncarcinogens (8-hydroxyquinoline and benzyl alcohol), and nongenotoxic carcinogens (methyl carbamate and N-nitrosodiphenylamine). Any foci of size $\geq$2 mm regardless of invasiveness and piling was scored as positive in CTA with BALB/3T3. As expected, four carcinogens regardless of their genotoxicity had positive outcomes in two-stage CTA using BALB/3T3 cells. However, of the two genotoxic noncarcinogens, benzyl alcohol was positive CTA finding. We concluded that, of the 6 chemicals tested, the sensitivity for BALB/3T3 system was reasonably high, being 100%. The respective specificity for BALB/3T3 assay was 50%. We also investigated the correlation between results of BALB/3T3 assay and results from HaCaT assay in order to develop a reliable human cell transformation assay. However, evaluation of staining at later time points beyond the confluency stage did not yield further assessable data because most of HaCaT cells were detached after $2{\sim}3$ days of confluency. Thus, after test article treatment, HaCaT cells were split before massive cell death began. In this modified protocol for this HaCaT system, growing attached colonies were counted instead of transformed foci 3 weeks since last subculture. Compared to BALB/3T3 assay, HaCaT assay showed moderate low sensitivity and high specificity. Despite these differences in specificity and sensitivity, both cell systems did exhibit same good concordance between in vitro CTA and rodent carcinogenicity findings (overall 83% concordant results). At present the major weakness of these in vitro CTA is lack of validation for regulatory acceptance and use. Thus, more controlled studies will be needed in order to be better able to assess and quantitatively estimate in vitro CTA data.

• BMB Reports
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• 제29권3호
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• pp.192-199
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• 1996

A rapid and sensitive method has been developed to detect a-fetoprotein (AFP) in human serum by a two-site sandwich enzyme-linked immunosorbent assay (ELISA) with monoclonal antibodies (MAbs) for human AFP within 1 h. To obtain the most sensitive and reliable MAbs. 12 kinds of MAbs (HPJ1 to HPJ12) as a capture antibody and 4 kinds of horseradish peroxidase (HRP) conjugated MAbs as a tracer antibody were investigated. Among these, only HPJ 10-HRP conjugated HPJ 1 (HPJ 10-HPJ $1^*$) and HPJ 11-HRP conjugated HPJ 10 (HPJ 11-HPJ $10^*$) were chosen as candidates based on the linearity of the standard curve and the sensitivity of the assay. To further characterize these two pairs. MAbs against human AFP were purified from hybridoma cells. conjugated with HRP. and then characterized to optimize the two-site sandwich ELISA The HPJ 10-HPJ $1^*$ pair showed a sensitivity of 1 ng/ml and a better reproducibility than the HPJ 11-HPJ $10^*$ pair when the human sera were incubated at $37^{\circ}C$ for 30 min. The results obtained for 480 randomly selected human sera showed 0~20 ng/ml of AFP values for the normal human sera. To test the utility of our kit, AFP concentrations were determined for 951 human sera (including 85 normal sera, 480 random blood sera, 213 HBsAg-positives. 50 anti-HCV antibody positives. and 47 malignant diseases) and compared with other commercially available AFP detecting kits. These results show that the present two-site sandwich ELISA method is a rapid, sensitive, and reliable procedure for detecting AFP in human serum.

• 한국동물위생학회지
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• 제31권3호
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• pp.315-329
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• 2008

A total of 710 bovine serum samples which are composed 532 bovine serum samples showed negative reaction and 178 bovine serum samples showed positive reaction with tube agglutination test (TAT) from North area of Gyeong-nam, Korea were tested using all the 3 assays which are Rose-Bengal test(RBT), tube agglutination test (TAT) and enzyme-linked immunosorbent assay (ELISA, two types) and analyzed for evaluation of specificity, sensitivity, reproducibility and predictive value. In the comparison of serum antibody titer agglutination test, RBT showed almost agreement with TAT. In the comparison of TAT and two types of ELISA method, they showed difference in specificity and sensitivity about 5%. But there is no significant difference in detecting sensitivity between two types of ELISA method and TAT. In serologic tests for bovine brucellosis, the new assay ELISA would be a good candidate for serologic survey for bovine brucellosis in Korea because it is efficient in detecting many test samples quickly. But the serum agglutination tests (RBT, TAT) are more economical and easy assay for detection. In the test of comparison of antibody titer between first day of finding and 10 days after finding by TAT, there was no change in 55% (76/139) of positive cattle.

• Journal of Veterinary Science
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• 제25권2호
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• pp.28.1-28.11
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• 2024

Background: Porcine circovirus type 2 (PCV2) infection is ubiquitous around the world. Diagnosis of the porcine circovirus-associated disease requires clinic-pathological elements together with the quantification of viral loads. Furthermore, given pig farms in regions lacking access to sufficient laboratory equipment, developing diagnostic devices with high accuracy, accessibility, and affordability is a necessity. Objectives: This study aims to investigate two newly developed diagnostic tools that may satisfy these criteria. Methods: We collected 250 specimens, including 170 PCV2-positive and 80 PCV2-negative samples. The standard diagnosis and cycle threshold (Ct) values were determined by quantitative polymerase chain reaction (qPCR). Then, two point-of-care (POC) diagnostic platforms, convective polymerase chain reaction (cPCR, qualitative assay: positive or negative results are shown) and EZtargex (quantitative assay: Ct values are shown), were examined and analyzed. Results: The sensitivity and specificity of cPCR were 88.23% and 100%, respectively; the sensitivity and specificity of EZtargex were 87.65% and 100%, respectively. These assays also showed excellent concordance compared with the qPCR assay (κ = 0.828 for cPCR and κ = 0.820 for EZtargex). The statistical analysis showed a great diagnostic power of the EZtargex assay to discriminate between samples with different levels of positivity. Conclusions: The two point-of-care diagnostic platforms are accurate, rapid, convenient and require little training for PCV2 diagnosis. These POC platforms can discriminate viral loads to predict the clinical status of the animals. The current study provided evidence that these diagnostics were applicable with high sensitivity and specificity in the diagnosis of PCV2 infection in the field.

• Radiation Oncology Journal
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• 제19권2호
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• pp.163-170
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• 2001

목적 : 방사선조사후 세포의 생존 분획은 세포집락 측정기법으로 확인하는 것이 표준이나 많은 비용과 시간이 소요되는 단점을 갖고 있다. 이에 생존 세포의 tetrazolium염의 자색 formazan 침전물로의 환원시키는 능력에 그 기반을 둔 MTT 기법을 사용하여 세포집락 측정기법을 대체하기 위한 기법으로서의 유용성과 그 실행상의 최적조건을 규명하고자 하였다. 방법 : PCI-1, SNU-1066, NCI-H630, RKO등의 세포주에 0, 2, 4, 6, 8, 10 Gy의 방사선을 조사한 후 세포집락 측정 기법과 MTT기법으로 세포 생존 분획을 조사하였다. 세포집락 측정기법은 $25\;cm^2$ 폴리스티렌 배양 플라스크에 방사선량에 따라 다른 수의 세포를 분주한 후 24시간 동안 배양 후 방사선을 조사하였고 이를 $10\~14$일 동안 배양 후 염색하여 생성된 세포집락의 수를 측정하였다. MTT기법은 침전물의 용해과정이 필요없는 Premix WST-1 시약을 이용하여 시행하였다. MTT기법은 각각의 세포주에서 세포수와 흡광도간의 선형관계와 최적 실험조건을 확인한 이후 시행하였다. 이 기법은 방사선을 조사받은 세포에서는 지수적 성장을 회복한 이후와 방사선을 조사받지 않은 세포는 4회 이상의 세포분열을 거친 후에 시행하였다. 세포집락 측정기법 및 MTT기법을 통하여 얻은 세포 생존율을 구한 후 이를 지표로 비교하였다. 결과 : 각 기법으로 얻은 세포 생존율의 표준편차는 $5\%$ 내외였다. 2가지 방법으로 구한 세포 생존율은 t-test로 비교하였을 때 $0\~4\;Gy$에서는 통계적으로 유의한 차이가 없었으며 회귀분석 결과는 선형적 관계가 있었다$(R^2=0.975-0.992)$. MTT 기법의 시행에 최적인 세포수는 배양효율에 따라 다른 것으로 나타났는데, 배양효율이 $30\%$ 이상이면 300개 이하가, $30\%$ 미만인 경우는 $500\~1,000$개가 적당한 것으로 확인되었다. MTT기법은 6 배가시간 경과 이후에 시행하는 것이 세포집락 측정기법과 가장 근접하였으며 적어도 4 배가시간 이후에 시행하는 것이 필요할 것으로 사료되었다. 이에 따르면 배가시간이 3일 이하인 세포주가 세포 민감성 측정방법으로서 MTT 기법이 세포 집락 측정 기법을 대체하여 사용하기에 적합한 것으로 사료되었다. 결론 : 이상에서, MTT기법을 이용하여 방사선조사 후의 세포생존을 측정하기 위해서는 예비실험을 통해 각 세포주에서의 최적의 조건을 찾는 것이 필수적이며 이 조건하에서 MTT기법을 시행해야만 방사선에 의한 세포 민감성 측정에 이용될 수 있음을 확인하였다.