• Title/Summary/Keyword: Assay sensitivity

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Evaluation of a novel TaqMan probe-based real-time polymerase chain reaction (PCR) assay for detection and quantitation of red sea bream iridovirus

  • Kim, Guk Hyun;Kim, Min Jae;Choi, Hee Ju;Koo, Min Ji;Kim, Min Jeong;Min, Joon Gyu;Kim, Kwang Il
    • Fisheries and Aquatic Sciences
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    • v.24 no.11
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    • pp.351-359
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    • 2021
  • The red sea bream iridovirus (RSIV) belonging to genus Megalocytivirus is responsible for red sea bream iridoviral disease (RSIVD) in marine and freshwater fishes. Although several diagnostic assays for RSIV have been developed, diagnostic sensitivity (DSe) and specificity (DSp) of real-time polymerase chain reaction (PCR) assays are not yet evaluated. In this study, we developed a TaqMan probe-based real-time PCR method and evaluated its DSe and DSp. To detect RSIV, the probe and primers were designed based on consensus sequences of the major capsid protein (MCP) genes from megalocytiviruses including RSIV, infectious spleen and kidney necrosis virus (ISKNV), and turbot reddish body iridovirus (TRBIV). The probe and primers were shown to be specific for RSIV, ISKNV, and TRBIV-types megalocytiviruses. A 95% limit of detection (LOD95%) was determined to be 5.3 viral genome copies/µL of plasmid DNA containing the MCP gene from RSIV. The DSe and DSp of the developed real-time PCR assay for field samples (n = 112) were compared with those of conventional PCR assays and found to be 100% and 95.2%, respectively. The quantitative results for SYBR Green and TaqMan probe-based real-time PCR were not significantly different. The TaqMan probe-based real-time PCR assay for RSIV may be used as an appropriate diagnostic tool for qualitative and quantitative analysis.

Root Extract of Scutellaria Baicalensis Increases Gefitinib Sensitivity in H1975 Human Non-small Cell Lung Cancer Cells (H1975 세포에서 황금추출물에 의한 gefitinib 저항성 억제 효과)

  • Park, Shin-Hyung;Park, Hyun-Ji
    • Journal of Physiology & Pathology in Korean Medicine
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    • v.35 no.4
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    • pp.117-123
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    • 2021
  • Gefitinib, a first generation epidermal growth factor receptor tyrosine kinase inhibitor (EGFR TKI), provides obvious clinical benefit in patients with EGFR-mutant non-small cell lung cancer (NSCLC). However, patients ultimately develop gefitinib resistance which mainly caused by EGFR T790M secondary mutation. In the current study, we investigated whether the root extract of Scutellaria baicalensis (SB) overcomes gefitinib resistance. Gefitinib-resistant H1975 human NSCLC cells (EGFR L858R/T790M double mutant) were treated with gefitinib and/or ethanol extract of SB (ESB) to evaluate the effect of ESB on the gefitinib sensitivity. The cell viability was measured by MTT assay and trypan blue exclusion assay. The colony-forming ability was evaluated by anchorage-dependent colony formation assay. Combined treatment with gefitinib and ESB markedly decreased the cell viability and colony formation than single treatment with gefitinib or ESB in H1975 cells. In addition, cells treated with both gefitinib and ESB exhibited a significant increase of sub-G1 DNA content which indicates apoptotic cells compared with those treated with gefitinib or ESB alone. As a molecular mechanism, combined treatment with gefitinib and ESB strongly downregulated the phosphorylation of ERK and JNK than single treatment with gefitinib or ESB. Taken together, our results demonstrate that ESB sensitizes H1975 cells to gefitinib treatment. We cautiously propose that ESB can be used in combination with gefitinib for the advanced NSCLC patients with acquired resistance to EGFR TKIs.

Assessment of Sensitivity of Photo-Chromosomal Assay in the Prediction of Photo-carcinogenicity (광염색체이상시험의 광발암성 예측능력에 대한 평가)

  • Hong Mi-Young;Kim Ji-Young;Lee Young Mi;Lee Michael
    • Toxicological Research
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    • v.21 no.2
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    • pp.99-105
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    • 2005
  • Photo-mutagenic compounds have been known to alter skin cancer rates by acting as initiators or by affecting subsequent steps in carcinogenesis. The objectives of this study are to investigate the utility of photo-chromosomal aberration (photo-CA) assay for detecting photo-clastogens, and to evaluate its ability to predict rodent photocarcinogenicity. Photo-CA assay was performed with five test substances that demonstrated positive results in photo-carcinogenicity tests: 8-Methoxypsoralen (photoactive substance that forms DNA adducts in the presence of ultraviolet A irradiation), chlorpromazine (an aliphatic phenothiazine an alpha-adrenergic blocking agent), lomefloxacin (an antibiotic in a class of drugs called fluoroquinolones), anthracene (a tricyclic aromatic hydrocarbon a basic substance for production of anthraquinone, dyes, pigments, insecticides, wood preservatives and coating materials) and Retinoic acid (a retinoid compound closely related to vitamin A). For the best discrimination between the test substance-mediated genotoxicity and the undesirable genotoxicity caused by direct DNA absorption, a UV dose-response of the cells in the absence of the test substances was firstly analyzed. All 5 test substances showed a positive outcome in photo-CA assay, indicating that the photo-CA test is very sensitive to the photo-genotoxic effect of UV irradiation. With this limited data-set, an investigation into the predictive value of this photo-CA test for determining the photo-carcinogenicity showed that photo-CA assay has the high ability of a test to predict carcinogenicity. Therefore, the photo-CA test using mammalian cells seems to be a sensitive method to evaluate the photo-carcinogenic potential of new compounds.

Development of Enzyme-Linked Immunosorbent Assay for Rapid and Sensitive Analysis of Biotin (Biotin의 분석을 위한 효소면역측정법(ELISA)의 개발)

  • 이경애;손동화;고영태
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.27 no.6
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    • pp.1152-1159
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    • 1998
  • In order to develop more rapid and reproducible analysis of biotin known as vitamin H, attempts were made to establish the condition for enzyme linked immunosorbent assay(ELISA) compared with traditional microbiological assay(MBA). Antibiotin and antiserum were obtained from the immunized rabbits injected with emulsion of biotin KLH conjugate and Freund's adjuvant. The antiserum showed cross reactivity on biocytin, a derivative of biotin, which is converted to biotin in intestine, at the rate of 177%(median inhibitory concentration(IC50)=12.58ppb), but not on other derivatives such as desthiobiotin, diaminobiotin and 2 imino biotin. Specific antibody for biotin was purified from the antiserum through protein A column and desalting column. The conditions of competitive direct ELISA (cdELISA) were established. Detection range of biotin concentration by cdELISA was 0.01∼300ng/ ml(ppb). In the spike test with milk, fruit flake and pine carrot juice, the correlation coefficient between two methods of MBA and ELISA was reliably consistent at the value of r=0.992. But detection of biotin by microbiological assay(MBA) was rather restricted in range and nonspecific. Detection range of biotin by MBA was 0.1∼0.5ng/ml(ppb). It showed cross reactivities on biocytin and desthiobiotin at the rate of 80.1% and 66.7%, respectively. In conclusion, ELISA revealed a significant improvement compared with MBA for the biotin detection in terms of sensitivity, detection range and cross reactivity. In addition, a variety of samples could be analyzed rapidly and conveniently at one time by using ELISA. These results strongly suggest that the ELISA is very promising for the practical application to detect biotin contents in a wide range of food stuffs.

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A Liquid-Based Colorimetric Assay of Lysine Decarboxylase and Its Application to Enzymatic Assay

  • Kim, Yong Hyun;Sathiyanarayanan, Ganesan;Kim, Hyun Joong;Bhatia, Shashi Kant;Seo, Hyung-Min;Kim, Jung-Ho;Song, Hun-Seok;Kim, Yun-Gon;Park, Kyungmoon;Yang, Yung-Hun
    • Journal of Microbiology and Biotechnology
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    • v.25 no.12
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    • pp.2110-2115
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    • 2015
  • A liquid-based colorimetric assay using a pH indicator was introduced for high-throughput monitoring of lysine decarboxylase activity. The assay is based on the color change of bromocresol purple, measured at 595 nm in liquid reaction mixture, due to an increase of pH by the production of cadaverine. Bromocresol purple was selected as the indicator because it has higher sensitivity than bromothymol blue and pheonol red within a broad range and shows good linearity within the applied pH. We applied this for simple determination of lysine decarboxylase reusability using 96-well plates, and optimization of conditions for enzyme overexpression with different concentrations of IPTG on lysine decarboxylase. This assay is expected to be applied for monitoring and quantifying the liquid-based enzyme reaction in biotransformation of decarboxylase in a high-throughput way.

Reverse transcription loop-mediated isothermal amplification assay for the rapid and simultaneous detection of H5 and other subtypes of avian influenza viruses

  • Park, Yu-Ri;Kim, Eun-Mi;Han, Do-Hyun;Kang, Dae-Young;Yeo, Sang-Geon;Park, Choi-Kyu
    • Korean Journal of Veterinary Service
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    • v.40 no.1
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    • pp.15-20
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    • 2017
  • A two-tube reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay was designed for the rapid visual detection of the M gene of all subtypes of avian influenza virus (AIV) and the H5 gene of the H5 subtype of highly pathogenic AIV (HPAIV). The reaction carried out in two tubes in a single step at $58^{\circ}C$ for 40 min, and the assay results could be visually detected by using hydroxynaphthol blue dye. Using M or H5 gene-specific primers, the assay successfully detected all subtypes or H5 subtypes of AIVs, including the Korean representative H5N1 and H5N8 HPAIVs. The detection limit of the assay was approximately $10^{2.0}$ $EID_{50}/reaction$ for the M and H5 genes of H5N1 HPAIV, respectively, and was more sensitive than that of previously reported RT-LAMP and comparable to that of real-time RT-PCR. These results suggest that the present RT-LAMP assay, with its high specificity, sensitivity, and simplicity, will be a useful diagnostic tool for surveillance of currently circulating H5 HPAIVs and other subtypes of AIV in bird population, even in under-equipped laboratories.

A Multiplex PCR Assay for the Detection of Food-borne Pathogens in Meat Products

  • Kim, Hyoun-Wook;Kim, Ji-Hyun;Rhim, Seong-Ryul;Lee, Kyung-A;Kim, Cheon-Jei;Paik, Hyun-Dong
    • Food Science of Animal Resources
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    • v.30 no.4
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    • pp.590-596
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    • 2010
  • Meat and meat products are a potential source of food-borne pathogens, including Staphylococcus aureus, Salmonella spp., Escherichia coli O157:H7, and Bacillus cereus. A sensitive and specific PCR assay for the detection of these pathogens in meat and meat products was developed in this study, as part of a broader effort to reduce the potential health hazards posed by these pathogens. Initially, PCR conditions were standardized with purified DNA. Under standard conditions, the detection level for PCR was as low as 10 pg of purified bacterial DNA. After overnight growth of bacteria in a broth medium, as few as $10^2$ CFU of bacteria were detected by PCR assay. The primers employed in the PCR assay were found to be highly specific for individual organisms, and evidenced no cross-reactivity with heterologous organisms. Additionally, the multiplex PCR assays also amplified some target genes from the four pathogens, and multiplex amplification was obtained from as little as 10 pg of DNA, thus illustrating the excellent specificity and high sensitivity of the assay. In conclusion, this PCR-based technique provides a sensitive and specific method for the detection of S. aureus, Salmonella spp., E. coli O157:H7, and B. cereus in meat and meat products.

Production of Polyclonal Antibody against $\alpha$-Fetoprotein and Polyclonal Antibody-Based Competitive Enzyme-Linked Immunosorbent Assay for $\alpha$-Fetoprotein (인간 $\alpha$-fetoprotein (AFP)에 대한 폴리클로날 항체의 생산 및 $\alpha$-fetoprotein 측정용 효소면역분석법 (competitive ELISA)의 개발)

  • Michung Yoon
    • Biomedical Science Letters
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    • v.3 no.2
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    • pp.115-123
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    • 1997
  • $\alpha$-Fetoprotein (AFP) has been a useful marker in screening and/or monitoring patients with hepatocellular carcinoma, gonadal germ cell tumor, gastric carcinoma and neural tube defects. In the present study, it was attempted to produce anti-human AFP polyclonal antibodies and to develop a competitive enzyme-linked immunosorbent assay (ELISA) for the measurement of AFP in human plasma and amniotic fluid. AFP was isolated from amniotic fluid using an isolation procedure consisting of affinity chromatography and preparative polyacrylamide gel electrophoresis. The antibody directed against AFP was raised in rabbits. Double immunodiffusion and Western blotting methods showed that the antiserum was highly specific, reacting with only AFP-containing samples. Standard curve was obtained by using purified AFP and specific antiserum. The assay sensitivity was 5ng/ml and the working range was 5~l,000ng/ml. The within-assay and between-assay coefficient of variance (CV) was 4.5% and 8.5%, respectively. These results indicate that the assay is valuable for the measurement of AFP and found to be simple, reproducible, and accurate.

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Rapid One Step Detection of Pathogenic Bacteria in Urine with Sexually Transmitted Disease (STD) and Prostatitis Patient by Multiplex PCR Assay (mPCR)

  • Lee, Sang-Rok;Chung, Ji-Min;Kim, Young-Gon
    • Journal of Microbiology
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    • v.45 no.5
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    • pp.453-459
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    • 2007
  • We developed a multiplex PCR (mPCR) assay to simultaneously detect Chlamydia trachomatis, Neisseria gonorrhoeae, Mycoplasma genitalium, Ureaplasma urealyticum, Corynebacterium spp. and seudomona aeruginosa. This method employs a single tube and multiple specific primers which yield 200, 281, 346, 423, 542, and 1,427 bp PCR products, respectively. All the PCR products were easily detected by agarose gel electrophoresis and were sequenced to confirm the specificity of the reactions. To test this method, DNA extracted from urine samples was collected from 96 sexually transmitted disease or prostatitis patients at a local hospital clinical center, and were subjected to the mPCR assay. The resulting amplicons were cloned and sequenced to exactly match the sequences of known pathogenic isolates. N. gonorrhoeae and Corynebacterium spp. were the most frequently observed pathogens found in the STDs and prostatitis patients, respectively. Unexpectedly, P. aeruginosa was also detected in some of the STD and prostatitis samples. More than one pathogen species was found in 10% and 80.7% of STD and prostatitis samples, respectively, indicating that STD and prostatitis patients may have other undiagnosed and associates. The sensitivity of the assay was determined by sing purified DNA from six pathogenic laboratory strains and revealed that this technique could detect pathogenic DNA at concentrations ranging from 0.018 to $1.899\;pg/{\mu}l$. Moreover, the specificities of this assay were found to be highly efficient. Thus, this mPCR assay may be useful for the rapid diagnosis of causative infectious STDs and prostatitis. useful for the infectious STDs and prostatitis.

Probe-based qPCR Assay for Rapid Detection of Predominant Candida glabrata Sequence Type in Korea

  • Bae, Jinyoung;Lee, Kyung Eun;Jin, Hyunwoo
    • Biomedical Science Letters
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    • v.25 no.4
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    • pp.407-416
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    • 2019
  • Recent years have seen an increase in the incidence of candidiasis caused by non-albicans Candida (NAC) species. In fact, C. glabrata is now second only to C. albicans as the most common cause of invasive candidiasis. Therefore, the rapid genotyping specifically for C. glabrata is required for early diagnosis and treatment of candidiasis. A number of genotyping assays have been developed to differentiate C. glabrata sequence types (STs), but they have several limitations. In the previous study, multi-locus sequence typing (MLST) has performed with a total of 101 C. glabrata clinical isolates to analyze the prevalent C. glabrata STs in Korea. A total of 11 different C. glabrata STs were identified and, among them, ST-138 was the most commonly classified. Thus, a novel probe-based quantitative PCR (qPCR) assay was developed and evaluated for rapid and accurate identification of the predominant C. glabrata ST-138 in Korea. Two primer pairs and hybridization probe sets were designed for the amplification of internal transcribed spacer 1 (ITS1) region and TRP1 gene. Analytical sensitivity of the probe-based qPCR assay was 100 ng to 10 pg and 100 ng to 100 pg (per 1 μL), which target ITS1 region and TRP1 gene, respectively. This assay did not react with any other Candida species and bacteria except C. glabrata. Of the 101 clinical isolates, 99 cases (98%) were concordant with MLST results. This novel probe-based qPCR assay proved to be rapid, sensitive, highly specific, reproducible, and cost-effective than other genotyping assay for C. glabrata ST-138 identification.