The Stratus immunofluorometric assay system evaluated for quantifying human choriogonadotropin in serum

We evaluated the Stratus (American Dade, Miami, FL), an automated immunofluorometric assay system, for the quantification of human choriogonadotropin (hCG) in serum or plasma. The assay is based on the "sandwich" (two-site) immunoassay methodology: use of two monoclonal antibodies, one specific for the alpha subunit and the other for the beta subunit, results in an assay that is specific for the intact hCG molecule. Results for the first sample are obtained in 7 min; subsequent additional values are produced at 1-min intervals. Inter-run precision (CV), estimated from replicate determinations of sera, was 4.5% at an hCG concentration of 38 int. units/L, 4.9% at 114, and 6.1% at 194. Intrarun CV was less than 2% at all three concentrations. Correlations of results for 127 specimens analyzed in duplicate with the Stratus (y) and by a radioimmunoassay (x) for beta hCG (Gamma Dab M [cf931125I] beta-hCG, Travenol-Genentech Diagnostics, Cambridge, MA) yielded the following regression equation: y = 0.969x - 6.0 (r = 0.995). The Stratus immunofluorometric system provides a rapid and convenient assay of hCG in serum or plasma.     

Analytical performance of three commercially available nephelometers compared for quantifying proteins in serum and cerebrospinal fluid

We investigated the analytical performance and imprecision of three commercially available nephelometers for the quantification of various proteins in pooled serum and cerebrospinal fluid. Albumin, transferrin, IgG, IgA, and IgM in serum were determined nephelometrically (BNA, Behring; Array, Beckman) and turbidimetrically (Cobas Bio, Hoffmann-La Roche). All these proteins in cerebrospinal fluid except transferrin were determined nephelometrically with all three systems. CVs and lower limits of detection were compared for all instruments, and stability of calibration curves was evaluated.     

Radioreceptor assay for quantifying FK-506 immunosuppressant in whole blood.

We describe a quantitative radioreceptor assay (RRA) for quantifying FK-506 in whole blood. FK-506 extracted from whole blood with a cyclohexyl-sorbent column competes with [3H]dihydro-FK-506 for binding to a partially purified preparation of FK-506 binding protein (FK-BP). Free and protein-bound FK-506 are separated on LH 20 Sephadex chromatographic columns. We compared the results of this method with those of an enzyme immunoassay that uses a monoclonal antibody: r = 0.97, Sy/x = 0.039. Between-day precisions (CV) at FK-506 concentrations of 8 and 17 micrograms/L were 9.2% and 8.2%, respectively. Within-run precisions were 5.9%, 8.1%, and 9.4%, respectively, at 4, 8, and 15 micrograms/L. Analytical recovery, evaluated at 5, 10, 15, 20, and 25 micrograms/L for FK-506 added to whole blood, ranged from 98% to 103%. The assay can reliably quantify FK-506 blood concentrations between 1.0 and 25 micrograms/L.     

Automated and manual quantitative assays of choriogonadotropin in serum compared

We found the analytical performance of a rapid, automated assay of human choriogonadotropin (hCG) in serum, the Stratus hCG Fluorometric Enzyme Immunoassay, superior to a widely used manual assay for hCG (Hybritech Tandem-E hCG). The two assays were comparable in sensitivity; recovery; cross reactivity with lutropin, follitropin, and thyrotropin; and freedom from interference from hemoglobin and bilirubin. Patient-correlation studies indicated good quantitative agreement [Stratus hCG = (1.08 X Tandem hCG) - 4.3 int. units/L]. However, intra- and interassay precision was substantially better with the Stratus hCG assay, and this may allow earlier confirmation of pregnancy.     

A multi-center evaluation of a new immunoenzymometric assay for human choriogonadotropin

A new, rapid, monoclonal immunoenzymometric assay for human choriogonadotropin (HCG), the Enzymun-Test HCG (Boehringer Mannheim GmbH), was evaluated by 15 laboratories in 10 European countries. Inter-assay percent CVs ranged from 5.4 to 40.5, 2.4 to 15.4, and 2.3 to 17.1 for low, medium, and high dose sera, respectively. Mean assay sensitivity was 0.34 mIU/mL HCG. Analytical recovery in serum ranged from 75 to 119%. Serial dilutions of HCG in normal human serum and in assay zero standard were found to be linear. Cross-reactivity with lutropin, follitropin, and thyrotropin was negligible. Serum reference values were established for normals and all stages of pregnancy. Comparative studies with nine other HCG immunoassays were carried out using a range of normal, pregnancy, and tumour sera. We conclude that this is an acceptable assay for monitoring HCG-producing tumours and pregnancy.     

Fluorescence depolarization assay for quantifying alpha-amylase in serum and urine

We have developed a new method for quantifying alpha-amylase (EC 3.2.1.1) in serum and urine by fluorescence depolarization. Amylase in the sample catalyzes the hydrolysis of the substrate, a fluorescein-labeled amylose. This results in decreased fluorescence polarization, owing to the increased rate of rotation of the amylose fragment relative to the intact substrate. The TDx amylase assay is calibrated with six human-serum-based pancreatic amylase calibrators. Amylase activities are determined by interpolation from the calibration curve, which is stored in the TDx analyzer's memory. Results correlate well with those by the Du Pont aca assay and the Beckman "DRI-STAT" assay. Endogenous glucose does not interfere. CVs are less than 6%, and the reagents are stable in liquid form.     

A new colimetric assay for monoamine oxidase in serum and its clinical application.

A new colimetric assay for serum monoamine oxidase and clinical findings based on this method are described. This rapid, precise procedure employs 1-[(4-aminomethylphenyl)azol]-2-naphthol as a substrate. The enzymatically generated 1-[(4-formyl phenyl)azo]-2-naphthol is extracted into cyclohexane to form a colored solution whose absorbance is determined at 500 nm. The method proved to be extremely simple, and the results obtained correlated well with those given by the standard method of McEwen.     

Simple quantitative measurement of serum choriogonadotropin compared with immunoradiometric, immunoenzymometric, and chemiluminescent assays.

We evaluated a new simplified quantitative method (Tandem Icon QSR; Hybritech) for choriogonadotropin (hCG), which could theoretically be performed in a ward or with outpatients. The method was compared with immunoradiometric (Bioclone Australia), chemiluminescent (Amerlite; Amersham), and immunoenzymometric assays (Stratus; Dade). We analyzed by each of the methods 104 serum samples from pregnant and nonpregnant patients. For quantitative hCG values indicative of pregnancy (greater than 25 int. units/L), excellent correlation was observed between the Tandem Icon method and the other standard laboratory assays (r = 0.995, 0.990, and 0.992, respectively). Occasional problems arose because of the instability of Tandem Icon QSR reagents at room temperature but this was resolved by storing the reagents at 4 degrees C. We conclude that this simplified quantitative method for hCG is reliable and suitable for use outside of the routine immunoassay laboratory.     

Criteria for evaluating nonquantitative assays: application to serum choriogonadotropin

We present guidelines for assessing the performance of nonquantitative (qualitative) assay methods. Criteria to be evaluated include analytical sensitivity, imprecision near limits of detection, analytical specificity, accuracy over a wide range of analyte concentrations, potential interferents, and technical ease of performance. A protocol was developed to evaluate several nonquantitative assay kits for detection of human choriogonadotropin (hCG) in serum. These include Tandem Icon HCG (Hybritech), Quest Pregnancy Test (Quidel), Concep-7 beta hCG (Leeco), and Beta Quik V (Pacific Biotech). Quantitative measurement of beta-hCG by RIA (Immophase beta hCG, Corning Medical) was used as the reference method. Results of this evaluation are discussed. The guidelines established and utilized in this report are adaptable to the evaluation of assay kits that measure other analytes by qualitative techniques.     

血小板聚集试验及其临床应用

目的探讨血小板聚集试验及其临床应用.方法以APACT2型血小板聚集仪用ADP为诱聚剂,探讨血小板聚集试验的影响因素,测定66例正常人及12例急性白血病患者的血小板聚集率,并观察阿斯匹林对血小板聚集试验的影响.用流式细胞术检测6例正常人及12例急性白血病患者的血小板膜糖蛋白Ⅱb/Ⅲa,比较血小板聚集试验与血小板膜糖蛋白Ⅱb/Ⅲa的结果.结果ADP应用的终浓度为5μgmol/L测定正常健康成人血小板聚集试验正常参考范围(χ±1.96s)为30.3%～86.3%.阿斯匹林对血小板聚集有抑制作用,与生理盐水对照组有显著差异(P＜0.02)急性白血病患者的血小板聚集率均值为5.4%,明显低于PRP为相同血小板浓度的正常人(28.7%)(P＜0.005).经等级相关分析血小板聚集试验与血小板膜糖蛋白Ⅱb/Ⅲa的检测有正相关(P＜0.0001).结论血小板聚集试验简便、实用可作为评价血小板聚集功能的初筛试验.     

Development of enzyme-linked immunosorbent assay for acidic fibroblast growth factor and its clinical application.

We have developed, for the first time, an enzyme-linked immunosorbent assay (ELISA) system for the measurement of human acidic fibroblast growth factor (aFGF). Anti-bovine aFGF rabbit IgG was conjugated with N-hydroxysuccimidobiotin, and the resulting IgG-biotin conjugate was used as the second antibody. This assay was highly specific and reproducible, enabling us to detect aFGF at a concentration as low as 1 microg/l without any prior processing of samples. With this method, it was possible to determine human aFGF up to 833 x 10(3) ng/l, with the use of anti-bovine aFGF IgG as the first and second antibody. There was no significant cross-reactivity of the antibody with other growth factors, such as basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF). The aFGF concentration in pericardial fluid was significantly higher in patients with unstable angina than in those with other heart diseases, suggesting that the aFGF plays an important role(s) in the course of collateral growth in coronary artery disease. Therefore, our ELISA system may be useful in determining unknown biological function(s) or pathological role(s) of aFGF in various disease entities.     

ELISpot技术的研究进展及临床应用

自ELISpot技术问世以来,由于其独特的优点,在基础与临床研究中的应用越来越广泛.目前,ELISpot技术为抗原表位筛查、抗原特异性T淋巴细胞定量、T淋巴细胞受体功能亲和力研究以及疫苗效果评价等提供了极其重要的技术平台;其在基础研究领域广泛应用的同时,ELISpot技术在临床中的应用也逐渐受到重视.现在,ELISpot技术正在疾病诊断与鉴别诊断、患者免疫状态和治疗效果评价以及疾病预后判断等方面发挥着重要作用.随着ELISpot技术的改进,相信ELISpot技术将为人类的健康事业做出更大的贡献.     

Measurement of choriogonadotropin by chemiluminescence immunoassay and immunochemiluminometric assay: 1. Use of isoluminol derivatives

We have developed immunoassays, monitored by the detection of chemiluminescence, for measuring choriogonadotropin in human urine. These methods involve the use of derivatives of isoluminol and include: (a) a labeled antigen with a second antibody covalently linked to polyacrylamide beads as the solid-phase reagent (i.e., solid-phase chemiluminescence immunoassay); and (b) an excess concentration of a specific antibody passively adsorbed onto the walls of polystyrene tubes and a labeled antibody of different specificity (i.e., two-site immunochemiluminometric assay). After the respective binding reactions, the solutions are aspirated, the antigen- or antibody-bound fractions are washed twice with 500 microL of buffer, sodium hydroxide (2 mol/L; 200 microL) is added, and the mixture is incubated for 60 min at 60 degrees C. After cooling, the label is oxidized with microperoxidase/hydrogen peroxide and the resulting chemiluminescence signal is measured for 10 s. We have evaluated the methods in terms of their sensitivity, precision, and clinical utility, and we compare results with values obtained by radioimmunoassay.     

Analytical and clinical performance of cPass neutralizing antibodies assay

Serological tests for SARS-CoV-2 are a critical component of disease control strategies. SARS-CoV-2 serology tests used in clinical diagnostic should not accurately evaluate total levels the antibodies but also closely correlate with neutralizing antibodies titers.However, only limited data is available reporting correlation of neutralization antibody assays with commercial high-throughput serological assays widely used in clinical laboratories.We performed evaluation of the GenScript cPass neutralizing antibody detection assay, to assess its value for routine clinical use to measure neutralizing titers in patients who recovered from coronavirus disease 2019 (COVID-19) or have been vaccinated. We tested its clinical performance against the commonly used Ortho Vitros IgG assay.Our combined data shows that GenScript cPass neutralizing antibody assay has satisfactory analytical and clinical performance and good correlation with Ortho Vitros IgG, supporting its use as a tool for accurate SARS-COV-2 immune surveillance of recovered or vaccinated individuals.