Direct ELISA

2015 ◽  
pp. 61-67 ◽  
Author(s):  
Alice V. Lin
Keyword(s):  
Direct Elisa

MONOCLONAL ANTIBODIES THAT RECOGNIZE Ca2+-INDUCED CONFORMER OF PROTEIN C, INDEPENDENT OF GLA RESIDUES

1987 ◽  
Author(s):  
T Sugo ◽  
S Tanabe ◽  
K Shinoda ◽  
M Matsuda
Keyword(s):  
Monoclonal Antibodies ◽  
Light Chain ◽  
Metal Binding ◽  
Binding Sites ◽  
Plasma Proteins ◽  
Protein C ◽  
The Other ◽  
Metal Binding Sites ◽  
Direct Elisa ◽  
Gla Domain

Monoclonal antibodies (MCA’s) were prepared against human protein C (PC) according to Köhler & Milstein, and those that recognize the Ca2+-dependent PC conformers were screened by direct ELISA in the presence of 2 mM either CaCl2 or EDTA. Out of nine MCAߣs thus screened, five MCA's designated as HPC-1˜5, respectively, were found to react with PC in the presence of Ca2+ but not EDTA. By SDS-PAGE coupled with Western Blotting performed in the presence of 2 mM CaCl2, we found that two MCA’s HPC-1 and 2, recognized the light chain, and two others, HPC-3 and 4, recognized the heavy chain of PC. But another MCA, HPC-5 was found to react with only non-reduced antigens. Further study showed that HPC-1 and 5 failed to react with the Gla-domainless PC, i.e. PC from which the N-terminal Gla-domain of the light chain had been cleaved off by α-chymotrypsin. However, all the other three MCA's retained the reactivity with the antigen in the presence of Ca2+ even after the Gla-domain had been removed. The binding of these MCA’s to PC in the presence of Ca2+ was found to be saturable with respect to the Ca2+ concentration and the half maximal binding for each MCA was calculated to be about 0.5+mM. Moreover, many other divalent cations such as Mg2+, Mn2+ , Ba2+, Zn2+, Co2+, Sr2+, were found to substitute for Ca2+ in inducing the metal ion-dependent but Gla-domain-independent conformer of PC.Cross-reactivity to other vitamin K-aependent plasma proteins was examined by direct ELISA; HPC-2 and 3 reacted solely to PC, but HPC-1 and 4 also reacted with prothrombin and HPC-5 with both prothrombin and factor X.These findings indicated that there are two or more metal binding sites besides the Gla-domain, possibly one in the light chain and the other(s) in the heavy chain. The presence of these metal binding sites may contribute to the unique conformer of vitamin K-dependent plasma proteins including protein C.

scholarly journals IgM and IgA Antibody Responses in 12 Cases of Human Acquired Toxoplasmosis

1997 ◽  
Vol 39 (6) ◽  
pp. 327-332 ◽  
Author(s):  
Emília E. H. TAKAHASHI ◽  
Cláudio L. ROSSI
Keyword(s):  
Serological Test ◽  
Clinical Manifestations ◽  
Enzyme Linked Immunosorbent Assay ◽  
Serum Samples ◽  
Igm Antibodies ◽  
Iga Antibodies ◽  
Direct Elisa ◽  
Acute Toxoplasmosis ◽  
Antibody Levels ◽  
Acquired Toxoplasmosis

The persistence, in some subjects, of specific IgM antibodies to Toxoplasma gondii for several months after the acute phase of infection has complicated the interpretation of serological test results for toxoplasmosis. Several reports have emphasized the value of the detection of Toxoplasma-specific IgA antibodies for the diagnosis of acute toxoplasmosis. In this article, we report the follow-up profiles of Toxoplasma-specific IgM and IgA antibodies in serum samples obtained from 12 patients at various intervals after the onset of the clinical manifestations of infection. IgM antibodies were detected by the indirect immunofluorescence (IIF) test, antibody capture enzyme-linked immunosorbent assay (cELISA) and enzyme-mediated chemilluminescent technique (CmL). IgA antibodies were quantified by the direct ELISA (dELISA) and cELISA procedures. As defined by the manufacturer of the cELISA test for IgA used, most patients with acute toxoplasmosis have antibody levels > 40 arbritary units per ml (AU/ml). At values > 40 AU/ml, the cELISA for IgA detected significant antibody levels for a shorter time than the other techniques used for IgM and IgA detection. However, IgA levels <FONT FACE="Symbol">£</font> 40 AU/ml do not exclude the possibility of acute toxoplasmosis since such levels can be reached very soon after infection with T. gondii. The results obtained in the present study show that the serological diagnosis of acute toxoplasmosis may not be such an easy task. Our data suggest that use of the IgA-cELISA concomitantly with IgM antibody screening could permit, in some circumstances, a more efficient diagnosis of acute acquired toxoplasmosis

Thrombocytopenia after abciximab use results from different mechanisms

2010 ◽  
Vol 103 (03) ◽  
pp. 651-661 ◽  
Author(s):  
Gisèle Clofent-Sanchez ◽  
Pierre Coste ◽  
Paquita Nurden ◽  
Sophie Lajus ◽  
Catherine Jais ◽  
...  
Keyword(s):  
Coronary Artery Disease ◽  
Monoclonal Antibody ◽  
Flow Cytometry ◽  
Platelet Count ◽  
Time Dependent ◽  
Sensitive Test ◽  
Direct Elisa ◽  
Drug Dependent ◽  
Artery Disease ◽  
Antibody Specificities

SummaryOur study concerns thrombocytopenia in patients with acute ischaemic coronary artery disease receiving antiplatelet drugs to the αIIbβ3 inte-grin (GPIIb/IIIa). We have screened for drug-dependent antibodies (DDAB) in 18 patients who suffered a fall of > 50% in platelet count (9 patients had a nadir of <50,000 platelets/μl) after receiving abciximab and related results to clinical outcome. Serum or plasma was screened for DDAB using (i) a direct ELISA against purified αIIbβ3, αIIbβ3-abciximab complexes or abciximab alone, (ii) control platelets and flow cytometry and (iii) monoclonal antibody immobilisation of platelet antigens. DDAB were found for 11 patients, with αIIbβ3 ELISA the most sensitive test. Progressive platelet consumption linked with haemoglobin loss and/or use of intra-aortic balloon pumping, another potential cause of a fall in platelet count, was also evaluated. DDAB were identified that recognised αIIbβ3 associated with abciximab and/ or abciximab alone. Screening of both progressive and delayed thrombocytopenia (appearing after 5 to 11 days) suggested that antibodies against abciximab preceded those recognising neo-epitopes on αIIbβ3, with a time-dependent broadening of antibody specificities. Higher titres were seen after second abciximab use. Five antibodies were platelet-activating. In conclusion, the mechanisms responsible for this complication of anti-αIIbβ3 therapy are multiple and often associated with a complex immune response.

scholarly journals Discovery of G-quadruplex stabilizing ligands through direct ELISA of a one-bead-one-compound library

2006 ◽  
Vol 4 (23) ◽  
pp. 4364 ◽  
Author(s):  
James E. Redman ◽  
Sylvain Ladame ◽  
Anthony P. Reszka ◽  
Stephen Neidle ◽  
Shankar Balasubramanian
Keyword(s):  
Compound Library ◽  
G Quadruplex ◽  
Direct Elisa ◽  
Stabilizing Ligands

Development of Competitive Direct ELISA for Gossypol Analysis

2005 ◽  
Vol 53 (14) ◽  
pp. 5513-5517 ◽  
Author(s):  
Jing Wang ◽  
Xi Wang ◽  
Feng Chen ◽  
Peter J. Wan ◽  
Guoqing He ◽  
...  
Keyword(s):  
Direct Elisa

Direct ELISA kits as a sensitive and selective screening method for abstinence control in urine

2011 ◽  
Vol 207 (1-3) ◽  
pp. 66-69 ◽  
Author(s):  
Katrin M. Kirschbaum ◽  
Frank Musshoff ◽  
Ansgar Wilbert ◽  
Jörg Röhrich ◽  
Burkhard Madea
Keyword(s):  
Screening Method ◽  
Selective Screening ◽  
Direct Elisa

A Direct Assay for Measuring Free 25-Hydroxyvitamin D

2017 ◽  
Vol 100 (5) ◽  
pp. 1318-1322 ◽  
Author(s):  
Nicolas Heureux ◽  
Ernst Lindhout ◽  
Leon Swinkels
Keyword(s):  
Liver Failure ◽  
Respiratory Diseases ◽  
Microtiter Plate ◽  
Cross Reactivity ◽  
Vitamin D Binding Protein ◽  
Calculation Methods ◽  
Hydroxyvitamin D ◽  
Pancreatic Cancers ◽  
Direct Elisa ◽  
25 Hydroxyvitamin D

Abstract Recent studies suggest that the concentration andgenotype of vitamin D binding protein (VDBP) are important factors that determine the bioavailability of25-hydroxyvitamin D [25(OH)D] in blood. Accumulatingdata indicate that, e.g., in pregnant women, hemodialysis patients, chronic kidney disease, liver failure, and bladder and pancreatic cancers, the measurement of free 25(OH)D in serum provides more relevant diagnostic information than measurement of total 25(OH)D. The aim of this study was to develop and validate an ELISA for direct measurement of free 25(OH)D in serum. A simple and direct ELISA was developed, based on a two-step immunoassay procedure performed ina microtiter plate. The assay has been characterizedin terms of precision (4–10% CV, according toconcentration), sensitivity (limits of blank = 0.5–1.0 pg/mL and LODs = 1.3–1.8 pg/mL), accuracy (correlation to dialysis, ELISA = 0.99xdialysis-0.5 pg/mL, r2 = 0.74), cross-reactivity of the antibody for the D2 form (77%),and addition of both VDBP and albumin (35–38%recovery upon addition of VDBP, 53–58% upon addition of albumin). The assay has already been usedin multiple studies, including its comparison with calculation methods and in studies of patients with liver failure, different ethnic groups, supplemented mice, respiratory diseases, and obesity. The free 25(OH)D ELISA can be used in studies as a valuable toolto establish the clinical relevance of free 25(OH)D.

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