A NEW METHOD BASED ON THE USE OF IMMOBILIZED SINGLE-DOMAIN ANTIBODIES TO REMOVE CERTAIN MAJOR PROTEINS FROM BLOOD PLASMA HELPS TO REDUCE NONSPECIFIC SIGNAL IN AN IMMUNOASSAY

A generally underestimated problem of immunoassays is its susceptibility to various interferences, being the Achilles heel of these assays (interventions in the analysis). The presence of interfering substances in the patient’s specimen can cause erroneous test sample result, which may lead to incorrect diagnosis and catastrophic consequences for the patient. Hence, one should pay particular attention to identifying possible interferences in the test systems used and, when possible, develop and apply methods to overcome them. The issue of avoiding interference is particularly important for immunoassays of biomarkers in human plasma or serum. In order to reduce possible interferences, it would be desirable to have an opportunity of specific and adaptable pretreatment of blood samples for a specifically assayed marker protein, as applied to a specific test system. We assume that such pretreatment may be done by combining the immunosorbents based on the use of special single-domain antibodies (nanobodies).The nanobodies are recombinant proteins, derivatives of single-domain antigen-recognizing variable fragments of specific antibodies, consisting of a dimer of truncated heavy chains in the complete absence of light chains. Such specific antibodies are detectable in the normal samples taken from members of the Camelidae family (Camelids), and in some species of cartilaginous fishes, along with the common antibodies. The special properties of nanobodies can provide certain advantages in their use, compared with antibodies of traditional structure and their derivatives.In this paper, we have shown for the first time, that the immunosorbents based on certain combination of single-domain antibodies used as ligands able for specifically binding and removal of specific high-abundance human blood proteins, may be selected for a given marker blood antigen in such a way that they will be an effective tool for blood pretreatment, aiming to reduce possible effects of interference and increased sensitivity in the diagnostic “sandwich” enzyme immunoassay. A new method of plasma pretreatment is demonstrated with human plasma samples (at a dilution of 1:40) of two patients. A previously developed model system for detection of lactoferrin protein was used to analyze plasma samples. It is shown that a significantly increased ratio of total detected signal to the nonspecific background signal could be obtained after drastic reduction of this background by affinity removal of 3 major protein fractions, i.e., fibrinogen, IgG alpha-2-macroglobulin from blood plasma samples, using appropriate immobilized single domain antibodies

One-pot isothermal DNA amplification Hybridisation and detection by a disc-based method

[EN] An integrated sensor comprising isothermal DNA amplification and in situ detection is presented. The method principle is based on recombinase polymerase amplification (RPA) and detection in the microarray format by compact disc technology as a high-throughput sensing platform. Primers were immobilised on the polycarbonate surface of digital versatile discs (DVD) and, after hemi-nested amplification, multiplexing identification of each tethered product was achieved by optical scanning with a 650 nm-laser of the DVD drive. The efficiency of one-pot hybridisation/elongation/detection depended strongly on probedensity and other factors such as the concentration of the unbound primers present in solution. The optimised conditions provided equivalent amplification factors (7.3 x 10(8) -8.9 x 10(8) fold) to those obtained by conventional reactions performed in vials. The proposed method was applied to Salmonella detection (generic by hns and oriC genes, and specific for subspecies I by STM4507 gene). A triplex assay was satisfactorily compared to the non-integrated protocols. Food and vaccine samples were analysed in a shorter time with less handling. The results indicate that the multiplex DVD assay is a simple, competitive, isothermal, portable system that is particularly useful for microbiological routine analysis. (C) 2014 Elsevier B.V. All rights reserved.This research has been funded through Projects GVA-PROMETEO/2010/008 (Generalitat Valenciana) and CTQ/2013/ 45875-R (MINECO). The Spanish Ministry of Education and Science provided S.S.F. with a grant for her PhD studies.Santiago Felipe, S.; Tortajada-Genaro, LA.; Morais, S.; Puchades, R.; Maquieira Catala, Á. (2014). One-pot isothermal DNA amplification Hybridisation and detection by a disc-based method. Sensors and Actuators B: Chemical. 204:273-281. https://doi.org/10.1016/j.snb.2014.07.073S27328120

Expression profiles of acute lymphoblastic and myeloblastic leukemias with ALL-1 rearrangements

The ALL-1 gene is directly involved in 5-10% of ALLs and AMLs by fusion to other genes or through internal rearrangements. DNA microarrays were utilized to determine expression profiles of ALLs and AMLs with ALL-1 rearrangements. These profiles distinguish those tumors from other ALLs and AMLs. The expression patterns of ALL-1-associated tumors, in particular ALLs, involve oncogenes, tumor suppressors, anti apoptotic genes, drug resistance genes etc., and correlate with the aggressive nature of the tumors. The genes whose expression differentiates between ALLs with and without ALL-1 rearrangement were further divided into several groups enabling separation of ALL-1- associated ALLs into two subclasses. Further, AMLs with partial duplication of ALL-1 vary in their expression pattern from AMLs in which ALL-1 had undergone fusion to other genes. The extensive analysis described here draws attention to genes which might have a direct role in pathogenesis

Trimeric Bet v 1-specific nanobodies cause strong suppression of IgE binding

BackgroundAround 20% of the population in Northern and Central Europe is affected by birch pollen allergy, with the major birch pollen allergen Bet v 1 as the main elicitor of allergic reactions. Together with its cross-reactive allergens from related trees and foods, Bet v 1 causes an impaired quality of life. Hence, new treatment strategies were elaborated, demonstrating the effectiveness of blocking IgG antibodies on Bet v 1-induced IgE-mediated reactions. A recent study provided evidence for the first time that Bet v 1-specific nanobodies reduce patients´ IgE binding to Bet v 1. In order to increase the potential to outcompete IgE recognition of Bet v 1 and to foster cross-reactivity and cross-protection, we developed Bet v 1-specific nanobody trimers and evaluated their capacity to suppress polyclonal IgE binding to corresponding allergens and allergen-induced basophil degranulation.MethodsNanobody trimers were engineered by adding isoleucine zippers, thus enabling trimeric formation. Trimers were analyzed for their cross-reactivity, binding kinetics to Bet v 1, and related allergens, and patients’ IgE inhibition potential. Finally, their efficacy to prevent basophil degranulation was investigated.ResultsTrimers showed enhanced recognition of cross-reactive allergens and increased efficiency to reduce IgE-allergen binding compared to nanobody monomers. Furthermore, trimers displayed slow dissociation rates from allergens and suppressed allergen-induced mediator release.ConclusionWe generated high-affine nanobody trimers that target Bet v 1 and related allergens. Trimers blocked IgE-allergen interaction by competing with IgE for allergen binding. They inhibited IgE-mediated release of biological mediators, demonstrating a promising potential to prevent allergic reactions caused by Bet v 1 and relatives

ALL-1/MLL1, a homologue of Drosophila TRITHORAX, modifies chromatin and is directly involved in infant acute leukaemia

Rearrangements of the ALL-1/MLL1 gene underlie the majority of infant acute leukaemias, as well as of therapy-related leukaemias developing in cancer patients treated with inhibitors of topoisomerase II, such as VP16 and doxorubicin. The rearrangements fuse ALL-1 to any of \u3e50 partner genes or to itself. Here, we describe the unique features of ALL-1-associated leukaemias, and recent progress in understanding molecular mechanisms involved in the activity of the ALL-1 protein and of its Drosophila homologue TRITHORAX