Time-resolved Fluorescence Immunoassay (TRFIA) for the Simultaneous Detection of MMP-9 and Lp-PLA2 in Serum.

Currently, atherosclerosis accounts for the majority of cardiovascular morbidity and mortality worldwide, and predicting the stability of atherosclerotic plaque is the main method to prevent atherosclerotic death. This study aims to establish a dual-label time-resolved fluorescence immunoassay (TRFIA) of matrix metalloprotein-9 (MMP-9) and lipoprotein-associated phospholipaseA2 (Lp-PLA2) to predict atherosclerotic plaque stability. A dual-label TRFIA was introduced for the simultaneous quantification of MMP-9 and Lp-PLA2 using fluorescent lanthanide (Eu3+ and Sm3+) chelates. The performance (sensitivity, specificity, accuracy, precision and reference intervals in different subjects) of this TRFIA was evaluated and compared with commercial kit. The sensitivity of the TRFIA for MMP-9 was 0.85 ng/mL and for Lp-PLA2 was 0.68 ng/mL with high affinity and specificity. The average recoveries were 94.58% to 109.82%, and 104.32% to 109.26%, respectively. All intra- and inter-assay CVs ranged from 3.10% to 5.46%. For the normal subjects, the cutoff value was 160.70 ng/mL for MMP-9 and 183.73 ng/mL for LP-PLA2; for the subjects with stable plaque, the cutoff value was 181.98~309.22 ng/mL for MMP-9 and 194.73~337.89 ng/mL for LP-PLA2; for the subjects with unstable plaque, the cutoff value was 330.43 ng/mL for MMP-9 and 343.23 ng/mL for LP-PLA2. This TRFIA detection results agreed well with the results of commercial kit (R2=0.9567 and R2=0.9771, respectively) in clinical serum samples. The TRFIA developed has a wide detection range and good sensitivity for the high-throughput simultaneous detection of MMP-9 and Lp-PLA2 in serum, which provides a new method for predicting the stability of atherosclerotic plaque.

The development of dual-label time-resolved fluorescence immunoassay (TRFIA) for screening of ovarian cancer based on simultaneous detection of human epididymis protein-4 and cancer antigen 125.

A two-step dual-label TRFIA was developed for the simultaneous detection of human epididymis protein-4 and cancer antigen 125 in a single run. The performance of this assay was first evaluated using clinical serum samples, and then compared with commercialized kits. The sensitivity of this assay for cancer antigen 125 detection was 0.5 U/mL (dynamic range, 0-1400 U/L), and the sensitivity for human epididymis protein-4 detection was 1 pM (dynamic range, 1-900 pM). High correlation coefficients (R) were obtained between the present dual-label TRFIA and commercially available kits (R = 0.99). The present dual-label TRFIA has high sensitivity, specificity, and accuracy in clinical sample analysis. It is a good alternative to the single-label diagnostic methods.

Proteomic analysis associated with coronary artery dilatation caused by Kawasaki disease using serum exosomes.

INTRODUCTION: The aim of this study was to investigate the serum exosome proteome profile of coronary artery dilatation (CAD) caused by Kawasaki disease (KD). METHODS: Two-dimensional electrophoresis was implemented on proteins of serum exosomes obtained from children with CAD caused by KD and from healthy controls. Differentially expressed proteins were identified by matrix-assisted laser desorption/ionization time-of-flight/time-of-flight mass spectrometry analysis. RESULTS: We identified 38 differentially expressed proteins (13 up-regulated and 25 down-regulated) from serum exosomes of patients with CAD caused by KD compared with healthy controls. Expression levels of three differentially expressed proteins (leucine-rich alpha-2-glycoprotein, sex hormone-binding globulin, and serotransferrin) were validated using western blot analysis. Classification and protein-protein network analysis showed that they are associated with multiple functional groups involved in the acute inflammatory response, defense response, complement activation, humoral immune response, and response to wounding. The majority of the proteins are involved in the inflammation and coagulation cascades. CONCLUSIONS: These findings establish a comprehensive proteome profile of CAD caused by KD and increase our knowledge of scientific insight into its mechanisms.

Labelled antibody-based one-step time-resolved fluoroimmunoassay for measurement of free thyroxine in serum.

BACKGROUND: Valid assays measuring free thyroxine (FT4) must perform without bias despite large variations in the concentrations and affinities of serum thyroxine-binding proteins in the population. We developed a new, rapid one-step labelled-antibody time-resolved fluoroimmunoassay (TRFIA) for FT4. METHODS: Based on the heterologous combination of anti-T4 monoclonal antibody and triiodothyronine-immunoglobulin G conjugate, a one-step TRFIA for FT4 detection was established and compared with the two-step DELFIA(®) Free Thyroxine Assay. Matrix interference caused by endogenous binders and exogenous non-esterified fatty acids (NEFA) was also accessed in the proposed assay. RESULTS: The developed method generally took only one hour, had a detection limit of 0.6 pmol/L and a large linear range of 2.5-120 pmol/L. The inter- and intra-assay coefficients of variation were 3.5-6.6% and 4.4-9.8%, respectively. Results from 110 specimens showed apparent agreement with that from the DELFIA(®) FT4 Assay with the square of the correlation coefficient of 0.975. This assay indicated that there was no significant dependence on endogenous binders and displayed potential interference by exogenous NEFA up to 5 mmol/L. CONCLUSIONS: The proposed one-step heterologous TRFIA FT4 assay possesses simplicity, accuracy, high sensitivity and exhibits great potential for FT4 measurement. The combination of heterologous immunoassay with TRFIA may be advantageous for FT4 immunoassay development.