Comparison of two commercial methods with a UHPLC-MS/MS method for the determination of multiple mycotoxins in cereals.

Immunoassay-based techniques are important on-site screening tools for the detection of mycotoxins in cereals. This study aims to evaluate the trueness, precision, repeatability and cross-reactivity of commercially available test strips, ELISA kits and UHPLC-MS/MS on analyzing zearalenone, ochratoxin A, deoxynivalenol, T-2 toxin and fumonisin B1. The results showed that false negative rate (25.7 %-37.4 %) of all tested mycotoxins by test strips was higher than the false positive rate (0 %-31.0 %). The repeatability of ELISA kits at the declared LOD dispersed from -85.7 % to +98.4 %. ELISA kits were more accurate at 50 % of the maximum residue limit (MRL) of mycotoxins than 150 % and 200 %. All the tested deoxynivalenol/zearalenone derivatives had cross-reactivity with different level, and sample matrix could reinforce this overestimation of target mycotoxin. This study emphasized that higher-quality antibody screening and more analytical performance investigations are need to address for on-site detection of mycotoxins in the future.

Phosphorylation of HSF1 by MAPK-activated protein kinase 2 on serine 121, inhibits transcriptional activity and promotes HSP90 binding.

Heat shock transcription factor 1 (HSF1) monitors the structural integrity of intracellular proteins and its regulation is essential for the health and longevity of eukaryotic organisms. HSF1 also plays a role in the acute inflammatory response in the negative regulation of cytokine gene transcription. Here we show, for the first time, that HSF1 is regulated by the proinflammatory protein kinase MAPKAP kinase 2 (MK2). We have shown that MK2 directly phosphorylates HSF1 and inhibits activity by decreasing its ability to bind the heat shock elements (HSE) found in the promoters of target genes encoding the HSP molecular chaperones and cytokine genes. We show that activation of HSF1 to bind HSE in hsp promoters is inhibited through the phosphorylation of a specific residue, serine 121 by MK2. A potential mechanism for MK2-induced HSF1 inactivation is suggested by the findings that phosphorylation of serine 121 enhances HSF1 binding to HSP90, a major repressor of HSF1. Dephosphorylation of serine 121 in cells exposed to non-steroidal anti-inflammatory drugs leads to HSP90 dissociation from HSF1, which then forms active DNA binding trimers. These experiments indicate a novel mechanism for the regulation of HSF1 by proinflammatory signaling and may permit HSF1 to respond rapidly to extracellular events, permitting optimal physiological regulation.

[The research on IR and TEM of polybutylcyanoacrylate nanoparticles].

Through latex polymerization with stabilizer (Dextran, low fraction), we prepared polybutylcyanoacrylate nanoparticles with a size of approximately 200 nm. The nanoparticle diameter decreases with decreasing stabilizer concentration. Using TEM and IR we studied the combination state and the mechanism between polybutylcyanoacrylate and Dextran. It was shown that each Dextran molecule could therefore contain several cyanoacrylate polymer moieties covalently linked via any of the available Dextran hydroxyl groups. Anchoring of the cyanoacrylate groups within the nanoparticle matrix would therefore result in an irreversible attachment between the Dextran and the nanoparticle. In this way, Dextran could be incorporated throughout the particle matrix as well as on the surface, producing the biodegradable particle. The results have been interpreted by reference to the accepted theories of steric stabilization and dispersion polymerization, and a model is proposed for the nanoparticle formation in the presence of Dextran.