Clinical studies & documents

Study on bacterial respiratory diseases in dogs using Lifeassays cCRP system 

S.J. Viitanen, H.P. Laurila, L.I. Lilja-Maula, M.A. Melamies, M. Rantala, and M.M. Rajamäki 

Acute-phase response (APR) refers to a complex systemic reaction occurring shortly after tissue injury. APR, as part of the innate host defense system, is a nonspecific response to various possible causes, including infectious, immunologic, neoplastic, or traumatic processes.1 APR is mainly mediated by pro-inflammatory cytokines, including interleukin-6, inter- leukin-1, and tumor necrosis factor-a secreted by local inflammatory cells such as monocytes and macrophag- es. This induces changes in plasma proteins, produced mainly in the liver, called acute-phase proteins (APPs).2 Major and minor positive APPs (eg, C-reactive protein [CRP], serum amyloid A, haptoglobin, alpha-1-acid glycoprotein, ceruloplasmin, fibrinogen) increase in the APR, and negative APPs (eg, albumin, transferrin) decrease.3 In dogs, CRP is a major APP. Its serum concentration is very low in healthy animals, but increases rapidly after stimuli, with a lag-phase of ~4 h, reaching peak concentrations ~24 h after the stimulus and then normalizing quickly during recovery.4 These characteristics make CRP a useful marker of ongoing inflammatory activity. ...
 

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Preparation of a portable point-of-care in vitro diagnostic system, for quantification of canine C-reactive protein, based on a magnetic two-site immunoassay.

Ibraimi F, Ekberg B, Kriz D, Danielsson G, Bülow L.

In this study, characterization of the binding kinetics and optimization of a magnetic permeability based point-of-care (POC) immunoassay system for quantification of canine C-reactive protein (cCRP) is described. The reagent is based on a two-site heterogeneous immunoassay system utilizing conjugated superparamagnetic nanoparticles (SPION) and silica particles, both particles carrying covalently linked antibodies directed to the cCRP analyte. Detection is carried out using a magnetic permeability-based small instrument, adjusted in order to apply it in a POC setting near the patients. The kinetic parameters are characterized and applied in the final design of the assay system. In the cCRP system studied, 90% of the binding between immobilized solid-phase silica antibody and cCRP is complete after only 15 s, and 30 s for the binding between the antibody on the SPION and the bound cCRP on the silica particle. Additionally, the binding rate constants are determined to be 149 and 30 M(-1)s(-1), respectively. The analytical sensitivity, clinical sensitivity, and imprecision verifies the clinical usefulness of the system. Also, quantification of cCRP, using the system described, in dog clinical samples from mixed breeds shows a high correlation to a commercially available comparative cCRP ELISA system (y = 0.98 × +3.2, R(2) = 0.98, n = 47). The immunoassay system described can thus provide the veterinarian a valuable tool for rapid diagnosis and monitoring of inflammatory diseases in dogs in a setting near the patients.
 

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Commissioned Research Report: Method evaluation and method comparison of LifeAssays canine CRP point-of-care system

The aim of the present study was to evaluate the analytical performance and reliability of the LifeAssays® Canine CRP System – a new magnetic permeability based assay for diagnostic measurements of canine C-reactive Protein (CRP). The performance was evaluated by assessment of components of analytical performance (intra- and interassay imprecision, detection limit and markers of inaccuracy; spike and recovery and linearity under dilution). Method comparison to a validated reference method was performed to further identify and characterize possible bias of clinical importance.

The analytical performance of the LifeAssays® Canine CRP system was acceptable with intra- and interassay coefficients of variations of 5.0-13.6% and 4.5-16.7%, respectively with the highest variations observed for measurements of CRP in serum with concentrations in the normal range (below the clinical decision level). Recovery of 60-89% and acceptable linearity under dilution were observed. Although a discrepancy exceeding the combined imprecision in the measured CRP levels was observed when compared to the reference method; a good agreement on diagnostic classification was present, suggesting the discrepancy to be of low clinical significance. The Life Assays® Canine CRP system performed reliably in determination of canine serum CRP for clinical purposes in a POCT setting, however, direct comparison of results with results from other systems should be done with caution. 
 

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