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Peter Gardiner - One of the best experts on this subject based on the ideXlab platform.
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multi center determination of galectin 3 assay performance characteristics anatomy of a novel assay for use in heart failure
Clinical Biochemistry, 2010Co-Authors: Robert H Christenson, Showhong Duh, Andrew Smith, Gyorgy Abel, Christopher Defilippi, Shunguang Wang, Aram Adourian, Carol Adiletto, Peter GardinerAbstract:Abstract Background Galectin-3 is a carbohydrate binding protein that plays many important regulatory roles in inflammation, immunity and cancer. Recent studies indicate that galectin-3 is a mediator of heart failure development and progression. Development of an improved assay for galectin-3 measurement was necessary for appropriate clinical assessment. Key analytical performance characteristics, the reference distribution and association of galectin-3 levels with clinical outcome in heart failure patients are defined. Methods A two-site ELISA test was examined for measurement matrix, imprecision, limits of blank, detection, and quantitation, as well as linearity, high-dose Hook Effect, storage stability, cross-reactivity with nine similar compounds, interference with 22 common medications and icterus, lipemia and hemolysis, all in accordance with CLSI guidance. Also the Effects of human anti-mouse antibodies and rheumatoid factor on recovery of galectin-3 were investigated. The reference interval was determined for 1092 ostensibly healthy individuals. The association of galectin-3 concentrations with an outcome of mortality was examined in a preliminary analysis of 129 acute decompensated heart failure patients. Results Galectin-3 results were equivalent when measured in serum or EDTA plasma. Imprecision studies demonstrated that the total CV was Conclusion This ELISA for galectin-3 measurement demonstrated acceptable analytical characteristics and was associated with mortality in a preliminary unadjusted analysis.
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multi center determination of galectin 3 assay performance characteristics anatomy of a novel assay for use in heart failure
Clinical Biochemistry, 2010Co-Authors: Robert H Christenson, Showhong Duh, Andrew Smith, Gyorgy Abel, Christopher Defilippi, Shunguang Wang, Aram Adourian, Carol Adiletto, Peter GardinerAbstract:Background Galectin-3 is a carbohydrate binding protein that plays many important regulatory roles in inflammation, immunity and cancer. Recent studies indicate that galectin-3 is a mediator of heart failure development and progression. Development of an improved assay for galectin-3 measurement was necessary for appropriate clinical assessment. Key analytical performance characteristics, the reference distribution and association of galectin-3 levels with clinical outcome in heart failure patients are defined. Methods A two-site ELISA test was examined for measurement matrix, imprecision, limits of blank, detection, and quantitation, as well as linearity, high-dose Hook Effect, storage stability, cross-reactivity with nine similar compounds, interference with 22 common medications and icterus, lipemia and hemolysis, all in accordance with CLSI guidance. Also the Effects of human anti-mouse antibodies and rheumatoid factor on recovery of galectin-3 were investigated. The reference interval was determined for 1092 ostensibly healthy individuals. The association of galectin-3 concentrations with an outcome of mortality was examined in a preliminary analysis of 129 acute decompensated heart failure patients. Results Galectin-3 results were equivalent when measured in serum or EDTA plasma. Imprecision studies demonstrated that the total CV was < 10% at a low concentration of 6 ng/mL, 7% near the mid-level concentration of 21 ng/mL, and 15% at the high level of 70 ng/mL. The limit of blank was 0.86 ng/mL, the limit of detection was 1.13 ng/mL, and the limit of quantitation was 0.96 ng/mL. The linear measurement range was 0.96–130 ng/mL and there was no high-dose Hook at levels up to 500 ng/mL. No cross-reactivity with nine compounds structurally related to galectin-3 and no interference from 22 common medications, icterus or lipemia was found. Hemolysis and presence of human anti-mouse antibodies or rheumatoid factor were found to be potential sources of interference. Samples can be stored for up to 15 days at either 22–28 °C or 2–8 °C before analysis; measurements are stable after storage at − 20 °C or − 70 °C for at least 6 months and through six freeze–thaw cycles. The 90th, 95th and 97.5th percentile of the normal reference interval was 17.6, 20.3 and 22.1 ng/mL, respectively. Galectin-3 in the acute decompensated heart failure patients ranged from 4.0 to 75 ng/mL; using a cutpoint of 22.1 ng/mL in an unadjusted analysis, galectin-3 values were associated with an outcome of death (p = 0.035). Galectin-3 is associated with severity of heart failure as indicated by NYHA Class (p-value for trend, 0.017). Conclusion This ELISA for galectin-3 measurement demonstrated acceptable analytical characteristics and was associated with mortality in a preliminary unadjusted analysis.
Jinming Lin - One of the best experts on this subject based on the ideXlab platform.
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evaluation of α fetoprotein afp in human serum by chemiluminescence enzyme immunoassay with magnetic particles and coated tubes as solid phases
Analytica Chimica Acta, 2009Co-Authors: Qianyun Zhang, Xu Wang, Jinming LinAbstract:Abstract In this work, the monoclonal antibodies (McAbs) to α-fetoprotein (AFP) were immobilized on two different solid phases, i.e., magnetic particles (MP) and coated tubes (CT). Based on this, a MP based chemiluminescence enzyme immunoassay (MP-CLEIA) and a CT based CLEIA (CT-CLEIA) were proposed for the evaluation of AFP in human serum and their analytical merits were studied and compared. By detailed discussion of several performance variants, including the concentration of immobilized McAb, dilution ratio of horseradish peroxidase (HRP) labeled McAb (HRP-McAb), total assay time, substrate volume, chemiluminescent kinetics, and Hook Effect concentration, the advantages of MP-CLEIA became conspicuously apparent. Moreover, in the presence of MP, the catalytic activity of labeled enzyme was kept to high extent and the stability of immunoreagents was satisfied. Finally, 59 human serum samples were detected by the MP-CLEIA and a good correlation was obtained when comparing the results with that from a commercial electrochemiluminescence immunoassay kit.
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development of high performance magnetic chemiluminescence enzyme immunoassay for α fetoprotein afp in human serum
Clinica Chimica Acta, 2008Co-Authors: Xu Wang, Qianyun Zhang, Xitang Ying, Jinming LinAbstract:Abstract Background A high-performance chemiluminescence enzyme immunoassay (CLEIA) for α-fetoprotein (AFP), a tumor marker for the diagnosis of hepatocellular carcinoma (HCC), was constructed by using magnetic particles (MPs) as both the immobilization matrix and separation tools. Methods A double sandwiched immunocomplex was formed through the reaction among anti-fluorescein isothiocyanate (FITC) antibody coated MPs, FITC-labeled anti-AFP antibody, AFP antigen, and alkaline phosphatase (ALP)-labeled anti-AFP antibody. The subsequent chemiluminescence reaction of ALP with 4-methoxy-4-(3-phosphate-phenyl)-spiro-(1,2-dioxetane-3,2′-adamantane) (AMPPD) gave light intensity that was directly proportional to the amount of analyte present in the samples. The Effects of several physicochemical parameters, including the concentration of FITC-labeled anti-AFP antibody, the dilution ratio of ALP-labeled anti-AFP antibody, the volume of MPs and substrate, the immunoreaction time and other relevant variables upon the immunoassay were studied and optimized. RIA and microplate CLEIA were used as comparison methods. Results The proposed method had a sensitivity of 3.0 ng/ml, low cross reactivities, and an assay time of 1 h. The linear range was 0–1200 ng/ml through using MPs and is useful for samples with extremely high AFP concentrations without dilution while avoiding the Hook Effect. The intra- and inter-assay precision was Conclusions This proposed assay provided apparent advantages over microplate CLEIA and RIA, and facilitated the development of high-throughput screening and automated operation systems in the clinical practice.
William F Chandler - One of the best experts on this subject based on the ideXlab platform.
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giant pituitary prolactinoma with falsely low serum prolactin the pitfall of the high dose Hook Effect case report
Neurosurgery, 1998Co-Authors: Ariel L Barkan, William F ChandlerAbstract:Objective and importance We present a case of a giant prolactinoma with a falsely low serum prolactin concentration determined by a two-site chemiluminometric assay. Awareness of the possibility of the "high-dose Hook Effect" in such cases will prevent preoperative misdiagnosis. Clinical presentation A patient with a giant invasive pituitary tumor was found preoperatively to have serum prolactin of 31 ng/ml. Pathological examination of the excised tissue, however, demonstrated strong staining for prolactin. Intervention Serial dilutions of the serum disclosed hyperprolactinemia of 280,000 ng/ml, establishing the presence of the "high-dose Hook Effect." Treatment with pergolide (Permax; Athena Neurosciences, S. San Francisco, CA) decreased tumor size and lowered serum prolactin by more than 99%. Conclusion A "high-dose Hook Effect" needs to be suspected in every patient with a giant pituitary adenoma (>3 cm) and normal serum prolactin. Subsequently assaying the diluted serum will reliably disclose this phenomenon and allow correct diagnosis and therapy.
Florent Bourgeois - One of the best experts on this subject based on the ideXlab platform.
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is the fish Hook Effect in hydrocyclones a real phenomenon
Powder Technology, 2013Co-Authors: Florent Bourgeois, A K MajumderAbstract:Although the fish-Hook Effect has been reported by many for a very long time, scientists and practitioners alike share contradictory opinions about this phenomenon. While some believe that it is of physical origin, others opine that it is the result of measurement errors. This article investigates the possibility that the fish-Hook Effect could indeed be measurement error related. Since all the experimental errors are embedded in the raw size distribution measurements, the paper first lays down the steps that lead to estimation of the partition function and confidence bounds, which are seldom reported in hydrocyclone literature, from the errors associated with the experimental size distribution measurements. Using several data sets generated using a 100 mm diameter hydrocyclone operating under controlled dilute to dense regimes, careful analysis of the partition functions following the developed methodology yields unambiguous evidence that the fish-Hook Effect is a real physical phenomenon. An attempt is also made to reunite some of the major contradictory views behind the existence of the fish-Hook based on sound statistical arguments.
Qianyun Zhang - One of the best experts on this subject based on the ideXlab platform.
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evaluation of α fetoprotein afp in human serum by chemiluminescence enzyme immunoassay with magnetic particles and coated tubes as solid phases
Analytica Chimica Acta, 2009Co-Authors: Qianyun Zhang, Xu Wang, Jinming LinAbstract:Abstract In this work, the monoclonal antibodies (McAbs) to α-fetoprotein (AFP) were immobilized on two different solid phases, i.e., magnetic particles (MP) and coated tubes (CT). Based on this, a MP based chemiluminescence enzyme immunoassay (MP-CLEIA) and a CT based CLEIA (CT-CLEIA) were proposed for the evaluation of AFP in human serum and their analytical merits were studied and compared. By detailed discussion of several performance variants, including the concentration of immobilized McAb, dilution ratio of horseradish peroxidase (HRP) labeled McAb (HRP-McAb), total assay time, substrate volume, chemiluminescent kinetics, and Hook Effect concentration, the advantages of MP-CLEIA became conspicuously apparent. Moreover, in the presence of MP, the catalytic activity of labeled enzyme was kept to high extent and the stability of immunoreagents was satisfied. Finally, 59 human serum samples were detected by the MP-CLEIA and a good correlation was obtained when comparing the results with that from a commercial electrochemiluminescence immunoassay kit.
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development of high performance magnetic chemiluminescence enzyme immunoassay for α fetoprotein afp in human serum
Clinica Chimica Acta, 2008Co-Authors: Xu Wang, Qianyun Zhang, Xitang Ying, Jinming LinAbstract:Abstract Background A high-performance chemiluminescence enzyme immunoassay (CLEIA) for α-fetoprotein (AFP), a tumor marker for the diagnosis of hepatocellular carcinoma (HCC), was constructed by using magnetic particles (MPs) as both the immobilization matrix and separation tools. Methods A double sandwiched immunocomplex was formed through the reaction among anti-fluorescein isothiocyanate (FITC) antibody coated MPs, FITC-labeled anti-AFP antibody, AFP antigen, and alkaline phosphatase (ALP)-labeled anti-AFP antibody. The subsequent chemiluminescence reaction of ALP with 4-methoxy-4-(3-phosphate-phenyl)-spiro-(1,2-dioxetane-3,2′-adamantane) (AMPPD) gave light intensity that was directly proportional to the amount of analyte present in the samples. The Effects of several physicochemical parameters, including the concentration of FITC-labeled anti-AFP antibody, the dilution ratio of ALP-labeled anti-AFP antibody, the volume of MPs and substrate, the immunoreaction time and other relevant variables upon the immunoassay were studied and optimized. RIA and microplate CLEIA were used as comparison methods. Results The proposed method had a sensitivity of 3.0 ng/ml, low cross reactivities, and an assay time of 1 h. The linear range was 0–1200 ng/ml through using MPs and is useful for samples with extremely high AFP concentrations without dilution while avoiding the Hook Effect. The intra- and inter-assay precision was Conclusions This proposed assay provided apparent advantages over microplate CLEIA and RIA, and facilitated the development of high-throughput screening and automated operation systems in the clinical practice.