Impact of antibody specificity and calibration material on the measure of agreement between methods for cardiac troponin I.

Background: Available assays for cardiac troponin I (cTnI) yield numerically different results. The aim of this study was to compare patient values obtained from four cTnI immunoassays.

Methods: We studied the Stratus(R) II assay, the Opus(R) II assay, the Access(R) assay, and a research-only cTnI heterogeneous immunoassay that uses the Dade Behring aca(R) plus immunoassay system equipped with two new noncommercial monoclonal antibodies.

Molecular mass determination for prostate-specific antigen and alpha 1-antichymotrypsin complexed in vitro.

The results from molecular mass determinations and amino acid analyses for prostate-specific antigen (PSA), alpha 1-antichymotrypsin (ACT) and PSA-ACT complexed in vitro are reported. Molecular masses for two separate PSA-ACT lots were determined by matrix-assisted laser desorption ionization mass spectroscopy (MALDI-MS) coupled to a time-of-flight (TOF) detector. Interestingly, both PSA-ACT lots contained two predominant protein species: 78,095 +/- 138 Da (approx.

Development and validation of an automated latex-enhanced immunoassay for prealbumin.

The measurement of circulating prealbumin has been shown to be clinically useful in the assessment of nutritional status, both as an initial screen and in the monitoring of nutritional recovery. We describe a fully automated, noncompetitive, homogeneous, light-scattering immunoassay that has been developed for this analyte on a Dimension (Dade) analyzer. A sheep anti-prealbumin IgG fraction was covalently coupled to 40-nm chloromethyl styrene particles and, after the addition of sample, polyethylene glycol-assisted immunoagglutination was monitored by turbidimetry.

Molecular targets of CD45 in B cell antigen receptor signal transduction.

Expression of the phosphotyrosine phosphatase CD45 is essential for B cell Ag receptor (BCR)-mediated p21ras activation and calcium mobilization. To examine the molecular basis of this requirement, we analyzed signaling events following BCR ligation in CD45-deficient (CD45-) and CD45-reconstituted (CD45+) variants of J558Lmicrom3 cells. Ag stimulation resulted in tyrosine phosphorylation of cellular proteins in both cells.

Manipulation of B cell antigen receptor tyrosine phosphorylation using aluminum fluoride and sodium orthovanadate.

The B cell antigen receptor complex (BCR) is composed of a membrane-spanning immunoglobulin molecule (mIg) non-covalently associated with heterodimers of the transmembrane proteins Ig-alpha and Ig-beta. The cytoplasmic domains of Ig-alpha and Ig-beta do not contain kinase domains but are phosphorylated on tyrosine residues immediately upon receptor ligation. The mechanism and kinase responsible for initial Ig-alpha and Ig-beta phosphorylation following receptor ligation is unknown, In an attempt to better understand this process, Ig-alpha and Ig-beta phosphorylation was examined in response to treatment of permeabilized B cells with the pharmacologic agents, aluminum fluoride (AlFx) and sodium orthovanadate (Na3VO4).