Avanços em Engenharia Automobilística
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Microdevice immunoassay with conjugated magnetic nanoparticles for rapid detection of anti-cyclic citrullinated peptide (anti-CCP)

Kenia Chávez Ramos, María del Pilar Cañizares Macías

Anti-cyclic citrullinated peptide IgG immunotoxin (anti-CCP) are produced as an immune response in the presence of post-translational modified peptides known as cyclic citrullinated peptides (CCP). Anti-CCP has been considered as specific biomarkers for the analysis of rheumatoid arthritis (RA), and due to its high specificity, it is possible to make a differential diagnosis of other rheumatic diseases. These immunotoxin can be detected in the early stages of RA and even up to 10 years before presenting the first symptoms of the disease opening a window of opportunity for timely treatment. The most widely used method for anti-CCP detection is an enzyme-linked immunosorbent assay (ELISA). Despite its great sensitivity, ELISA is considered as a time-consuming assay. In this work, a simple straight channel microdevice and CCP conjugated magnetic nanoparticles (MNPs-CCP) as solid support for quantifying anti-CCP was developed and tested for plasma. For the spectrophotometric analysis a microdevice with an optical flow Z cell design coupled with optical fibers was used. The microdevice immunoassay, employing only 6 L of samples and reagents, was almost nine times faster than a commercial anti-CCP ELISA kit but equivalent results were obtained. The identification range was 0.70-2000 U mL-1 with a constraint of discovery of 0.70 U mL-1 (16 times more delicate than the thought about ELISA pack). The microdevice immunoassay, with formed MNPs-CCP is a straightforward technique for against CCP evaluation being less expensive, faster and more delicate than the ELISA pack. Progressively, measures for the location of hostile to citrullinated peptide immunotoxin (ACPA) are used in RA determination. This audit sums up the biological premise and improvement of ACPA examines, accessible ACPA measures and their presentation attributes, and analytical properties of ACPA alone and contrasted with rheumatoid factor (RF) in early RA. We additionally survey relationships, accuracy, expenses and cost-feasibility, accessibility, soundness and reproducibility of the accessible examines. Taken together, information show that ACPA has a higher particularity than RF for early RA, great prescient legitimacy, high affectability, clear cost-adequacy and great strength and reproducibility. Given its boss execution qualities and expanding accessibility, ACPA is emerging as the most valuable single test for the analysis of RA. The determination of early rheumatoid joint inflammation (RA) has depended upon clinical measures, including history and current test discoveries, research facility and radiographic outcomes. Irreversible harm as often as possible happens right off the bat in RA. With mounting proof supporting early analysis and forceful treatment to forestall harm and inability, there is to improve ID and finding of early RA. As of not long ago, measures distinguishing rheumatoid factor (RF),immunotoxin coordinated against the Fc part of the immunoglobulin G (IgG) atom, have been the essential serological tests for RA finding. Against citrullinated peptide counter acting agent (ACPA) tests, created and popularized in the previous decade, are currently being used clinically. Since ACPA are present before the onset of RA symptoms and are predictive of RA development, they are a valuable diagnostic test early in the course of the disease. This review synthesizes currently available data regarding the diagnostic properties of RF and ACPA for the diagnosis of early RA. We focus on ACPA given their recent development and their potential role in the improved identification of early, undifferentiated RA. Data included in this review were obtained from medical literature searches, websites and contact with companies marketing the assays, and information and opinions obtained from experts in the field. We have included information on the biological basis and development of ACPA assays, the available assays, and data concerning assay performance characteristics, in particular those published in peer-reviewed journals, but also those publicized by manufacturers. Diagnostic properties of these tests, including, but not limited, to sensitivity, specificity, positive and negative predictive values, are reviewed. In 1940, Waaler observed that mixing serum from an RA patient with IgG-sensitized sheep erythrocytes inhibited hemolysis, but caused cell agglutination. Rose and colleagues later reported that RA sera agglutinated sheep erythrocytes coated with rabbit anti-sheep erythrocyte antibody more than did sera healthy individuals. These findings formed the basis of the earliest RA assay, the Waaler-Rose test. RF assays most commonly detect IgM antibodies directed against the Fc portion of the IgG molecule. The agglutination test measures RF IgM only and remains the most widely used assay. Agglutination assays are reported as either titers or units. Cut-offs for positivity are determined by manufacturers and based upon results from RA patients compared to healthy controls. Agglutination assays have sensitivities for RA from 70-85% and specificities ranging from 40-90%, as agglutination in individuals without RA may occur. Other assays for RF have been developed, including enzyme-linked immunosorbent assays (ELISAs), radioimmune assays (RIAs), and laser or rate nephelometry techniques. Assays for the detection of IgA and IgG RF are also available. The sensitivity of RF for RA diagnosis by these techniques is 50-90% and specificity is 50-95%. These wide ranges reflect differences in populations tested. Studies directly comparing RF detection techniques in cohorts of established RA patients, healthy controls, and patients with non-inflammatory joint disease, have reported latex agglutination test performance to be similar to that of nephelometry and radioimmune assays. In a meta-analysis of 50 studies of RF assays from 1998-2005,the pooled likelihood ratios (dependent upon both sensitivities and specificities) were quantitatively similar for IgM, IgA and IgG RF assays, and for using a higher versus lower RF titer for positivity. False positive RF results commonly occur in the setting of chronic infections, malignancy, and other rheumatic diseases. RF is detected in the sera of 1-4% of healthy young persons and in a higher percentage of elderly persons without RA. The RF assay however, is widely available, relatively inexpensive, and understood by both primary care physicians and arthritis specialists.Em 1964, Nienhuis e colegas descreveram um autoanticorpo que eles chamaram de fator antiperinuclear. Detectado por teste de imunofluorescência indireta em células da mucosa bucal humana, o fator antiperinuclear reconheceu o antígeno presente em grânulos de cerato-hialina ao redor do núcleo. O fator antiperinuclear estava presente em até 90% dos pacientes com AR estabelecida, com especificidade de 73-99%. Young e colegas detectaram posteriormente anticorpos antiqueratina usando imunofluorescência indireta em seções criogênicas de esôfago de rato .