Search results for "Haptens"
showing 10 items of 53 documents
Fluxapyroxad Haptens and Antibodies for Highly Sensitive Immunoanalysis of Food Samples
2017
Fluxapyroxad is a new-generation carboxamide fungicide, with residues increasingly being found in food samples. Immunochemical assays have gained acceptance in food quality control as rapid, cost-effective, sensitive, and selective methods for large sample throughput and in situ applications. In the present study, immunoreagents to fluxapyroxad were obtained for the first time, and competitive immunoassays were developed for the sensitive and specific determination of fluxapyroxad residues in food samples. Two carboxyl-functionalized analogues of fluxapyroxad were prepared, and antibodies with IC50 values in the low nanomolar range were generated from both haptens, though a dissimilar respo…
Antibody generation and immunoassay development in diverse formats for pyrimethanil specific and sensitive analysis
2012
Immunochemical techniques are complementary tools to modern analytical requirements. These methods rely on the production of immunoreagents with adequate binding properties. In the present study, a rationally designed and functionalized derivative of pyrimethanil-a modern anilinopyrimidine fungicide-was synthesized in order to generate for the first time high-affinity and selective antibodies to this xenobiotic. A single coupling procedure-based on hapten activation using N,N′-disuccinimidyl carbonate and purification of the active ester-was followed to prepare both immunizing and assay conjugates. Polyclonal antibodies were produced and characterized by enzyme-linked immunosorbent assay (E…
Circulating specific antibodies enhance systemic cross-priming by delivery of complexed antigen to dendritic cells in vivo
2012
Increasing evidence suggests that antibodies can have stimulatory effects on T-cell immunity. However, the contribution of circulating antigen-specific antibodies on MHC class I cross-priming in vivo has not been conclusively established. Here, we defined the role of circulating antibodies in cross-presentation of antigen to CD8(+) T cells. Mice with hapten-specific circulating antibodies, but naϊve for the T-cell antigen, were infused with haptenated antigen and CD8(+) T-cell induction was measured. Mice with circulating hapten-specific antibodies showed significantly enhanced cross-presentation of the injected antigen compared with mice that lacked these antibodies. The enhanced cross-pre…
Quantitative analysis of mixtures of metal-carbonyl complexes by Fourier-transform infrared spectroscopy: application to the simultaneous double immu…
1996
Abstract The feasibility of a double immunoassay of haptens by the nonisotopic carbonyl metalloimmunoassay (CMIA) method is demonstrated. Three different pairings of antiepileptic medications from the groups carbamazepine, diphenylhydantoin, and phenobarbital (for each of which a mono-CMIA is already available) were assayed by double CMIA. The assay method employs as tracers metal–carbonyl complexes that give very strong signals in the range of 1850–2200 cm −1 in the infrared spectrum, permitting quantitative analysis by Fourier-transform infrared spectroscopy. The fact that the signals are individually assignable and of comparable intensity permits quantitative analysis of mixtures of two …
Activation and translocation of p38 mitogen-activated protein kinase after stimulation of monocytes with contact sensitizers.
2002
Recently we described the induction of tyrosine phosphorylation by contact sensitizers as an early molecular event during the activation of antigen- presenting cells. In this study, the role of the p38 mitogen-activated protein kinase for the activation of human monocytes after exposure to four structurally unrelated contact sensitizers was analyzed in comparison with the irritant benzalkonium chloride and an inductor of oxidative stress (H 2 O 2 ) using immunofluorescence, Western blotting, and enzyme-linked immunosorbent assay techniques. Bio chemical analysis revealed a translocation of p38 from the cytoplasm to the detergent-resistant cell fraction only upon stimulation with contact sen…
Site-heterologous haptens and competitive monoclonal antibody-based immunoassays for pyrimethanil residue analysis in foodstuffs
2015
Pyrimethanil is a widely used post-harvest fungicide whose residues are commonly found in fruits and vegetables. We herein report the synthesis of two new functionalized derivatives of pyrimethanil carrying an equivalent spacer arm at different positions of the molecule. The influence of the linker tethering site on the affinity of monoclonal antibodies was shown. Moreover, the development of competitive immunoassays in different formats and with high sensitivity to the target analyte - IC50 values below 0.3μg/L - is described. Optimized assays were characterized by the determination of the limit of quantification, trueness, and precision using water-diluted QuEChERS extracts of fruits and …
Immunochemical rapid determination of quinoxyfen, a priority hazardous pollutant
2018
In 2013, quinoxyfen was included in the list of priority hazard pollutants of the European Water Framework Directive due to its toxicity to aquatic organisms. However, few analytical methods for the analysis of this fungicide have been reported and no rapid immunochemical methods have been published so far. In the present study, immunoreagents for quinoxyfen analysis were generated for the first time and an enzyme-linked immunosorbent assay was developed. Two carboxylated derivatives of quinoxyfen were designed on the basis of the minimum energy conformation of the target compound. Active esters of those novel compounds were prepared using N,N′-disuccinimidyl carbonate, and purified for cov…
Baculoviral display of functional scFv and synthetic IgG-binding domains.
2000
Viral vectors displaying specific ligand binding moities such as scFv fragments or intact antibodies hold promise for the development of targeted gene therapy vectors. In this report we describe baculoviral vectors displaying either functional scFv fragments or the synthetic Z/ZZ IgG binding domain derived from protein A. Display on the baculovirus surface was achieved via fusion of the scFv fragment or Z/ZZ domain to the N-terminus of gp64, the major envelope protein of the Autographa californica nuclear polyhedrosis virus, AcNPV. As examples of scFv fragments we have used a murine scFv specific for the hapten 2-phenyloxazolone and a human scFv specific for carcinoembryonic antigen. In pri…
Assessment of the Optimum Linker Tethering Site of Alternariol Haptens for Antibody Generation and Immunoassay Development
2021
Immunochemical methods for mycotoxin analysis require antigens with well-defined structures and antibodies with outstanding binding properties. Immunoreagents for the mycotoxins alternariol and/or alternariol monomethyl ether have typically been obtained with chemically uncharacterized haptens, and antigen conjugates have most likely been prepared with mixtures of functionalized molecules. For the first time, total synthesis was performed, in the present study, to obtain two haptens with opposite linker attachment locations. The functionalized synthetic haptens were purified and deeply characterized by different spectrometric methods, allowing the preparation of bioconjugates with unequivoc…
Contact Sensitizers Specifically Increase MHC Class II Expression on Murine Immature Dendritic Cells
2000
Contact sensitivity is a T-cell-mediated immune disease that can occur when low-molecular-weight chemicals penetrate the skin. In vivo topical application of chemical sensitizers results in morphological modification of Langerhans cells (LC). Moreover, within 18 h, LC increase their major histocompatibility complex (MHC) class II antigens expression and migrate to lymph nodes where they present the sensitizer to T lymphocytes. We wanted to determine if such an effect could also be observed in vitro. However, because of the high genetic diversity encountered in humans, assays were performed with dendritic cells (DC) obtained from a Balb/c mouse strain. The capacity of a strong sensitizer, DN…