Direct chromogenic substrate immuno-capture activity assay for testing of factor VII-activating protease.

Background: The Marburg I (MRI) single nucleotide polymorphism (SNP) of the factor VII-activating protease (FSAP) gene has been associated with thrombophilia and atherosclerotic disease. PCR is used to detect the SNP. Also, the specific FSAP activity to cleave single-chain urokinase-type plasminogen activator (scu-PA) serves as a surrogate for PCR testing.

Coagulation assays based on the Luminescent Oxygen Channeling Immunoassay technology 1).

Background: The Luminescent Oxygen Channeling Immunoassay (LOCI) technology is a well-established homogeneous assay format that allows for fast, accurate, and highly sensitive quantitation of analytes. We set out to develop and prove a novel concept to establish a LOCI format that should principally allow for the determination of the activity of coagulation factors and anticoagulants of clinical relevance.

Methods: The concept is based on the linkage of LOCI nano-beads by a peptide that can be cleaved by a coagulation factor.

Quantification of coagulation factor XIII activity by a thio-NADH based assay using factor XIII immuno-depleted plasma as a diluent for calibration.

Background: Accurate determination of factor XIII (FXIII) activity is crucial for replacement therapy. FXIII activity is typically determined using a coupled enzymatic reaction that measures nicotinamide adenine dinucleotide hydride (NADH) consumption at 340 nm.

Methods: Here, we describe the development of a prototype for a novel FXIII activity assay for detection at 405 nm by replacing NADH with thio-NADH, and the application of FXIII immuno-depleted plasma as a diluent for calibration.

Qualitative detection of the Marburg I alloenzyme of factor VII-activating protease by an immunoassay and its comparison to PCR testing.

Background: The Marburg I (MRI) single nucleotide polymorphism (SNP) of the factor VII-activating protease (FSAP) gene has been associated with thrombophilia, thromboembolism, atherosclerosis, and the incidence and progression of carotid stenosis. At present, MRI SNP testing is mainly performed using costly nucleic acid analysis. The ratio between FSAP activity and antigen concentrations in citrated plasma has been used to assess the FSAP genotype.

Tests for the measurement of factor VII-activating protease (FSAP) activity and antigen levels in citrated plasma, their correlation to PCR testing, and utility for the detection of the Marburg I-polymorphism of FSAP.

Background: The single nucleotide Marburg I (MRI) polymorphism of the factor VII-activating protease (FSAP) gene, the prourokinase-activating activity of FSAP, and antigen levels of FSAP in plasma have been associated with incidence and progression of carotid stenosis and venous thromboembolism. However, more information on the extent of these associations, potential further ones, and respective clinical utilities remain to be determined. At present, testing is performed mainly by PCR assays based on probes or SYBR Green I.