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ABSTRACT:Objective To construct V-set and immunoglobulin domain containing 4 (Vsig4)nanobodies (Nbs) as specific macrophage probes so as to use them as molecular probes of macrophagocytes.Methods A nanobody phage library was generated by using peripheral blood lymphocytes isolated from an alpaca immunized with recombinant Vsig4 protein.After three rounds of selection against recombinant Vsig4.The Nbs were subjected to sequencing and genome alignment to obtain VHH sequence.Nbs were isolated and tested for Vsig4 specificity in an ELISA using recombinant Vsig4.The affinity capacity of Nbs was verified by the cell line stably expressing Vsig4. Results A nanobody phage library with an estimated 7.27 × 107 clones with 70% insertion was successfully constructed.Totally 1 3 6 Vsig4-positive clones were sequenced and aligned according to different CDR3 sequences. In summary,1 5 Vsig4 nanobodies were obtained and grouped into 3 different CDR3 epitopes.The affinity of representing nanobody and Vsig4 was analyzed via ELISA;Nb1 1 9 showed the highest affinity against both recombinant and native Vsig4.Conclusion We successfully constructed and screened Vsig4 specific nanobody number 1 1 9 with high affinity and specificity.It can help with macrophage detection and in vivo monitoring.
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Objective To detect the changes of G protein-coupled inwardly rectifying potassium channels (GIRK)expression in allergic asthma model and identify the regulatory factors.Methods The E3 rat asthma models were induced by challenge with ovalbumin 14 days after immunization with ovalbumin and aluminium adjuvant.The asthma models were evaluated based on changes in lung pathomorphology and total IgE levels.The levels of GIRK1-4 mRNA and protein were detected using real time-PCR and Western blot.The anatomic sites where GIRK was expressed dominantly in the lung were identified using immunohistological staining.To identify the effects of IL-4 on the expressions of GIRK channels,GIRK 1 -4 mRNA and protein in IL-4 stimulated bronchial epithelial cell line A549 were detected by RT-PCR and Western blot.Results The levels of GIRK1-4 mRNA and protein decreased significantly in the lung in asthmatic E3 rats.The results of immunohistological staining showed that GIRK channels were dominantly expressed in airway epithelia in the lung.The levels of GIRK 1-4 mRNA and protein were down-regulated in time-and dose-dependent manners in IL-4 treated A549.Conclusion IL-4 down-regulates the expression levels of GIRK subunits in bronchial epithelia during allergic asthma.
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Objective To evaluate the feasibility of real-time quantitative PCR (RtPCR) with small volume regarding the stability, efficiency and reliability of amplification, and determine the optimal quantity of cDNA template suitable for small PCR volume. Methods The experiment was carried out in 3 groups with 10, 15 and 20μL reaction volume, respectively. In each group, rat β-actin mRNA was detected by RtPCR with 0.1, 0.2, 0.3 or 0.4μL rat cDNA as template, respectively. The amplification curve and melting curve were used to evaluate the reaction stability. The fitting of a curve of gradient templates against threshold cycle numbers was to show the reaction efficiency and the linear correlativity was to estimate the suitability of the template quantity. In addition, in order to estimate reliability, pristane-induced arthritis (PIA) rat model was established, and spleen TNF-α mRNA expression was detected by RtPCR with the selected reaction volumes. Results The amplification of rat β-actin mRNA was specific and stable in 10μL, 15μL and 20μL PCR volume, and had a high efficiency. Furthermore, the standard curves fitted by 0.1-0.4μL gradient templates showed a significant linear correlation in each volume group. When the 10μL and 20μL PCR volumes, and 0.2μL cDNA templates were chosen, the TNF-α mRNA expression in PIA rat spleen showed significant upregulation in both two volume groups as anticipated. Conclusion The experiment shows that it is feasible in the RtPCR amplification to use the small reaction volume of 10μL and 15μL, which has good stability and reliability. And 0.1-0.4μL templates are all suitable for the reaction system. PCR with small volume can not only save the reagents and template, especially rare clinical specimens, but also is helpful for the realization of high-throughput reaction.