Development of an enzyme-linked immunosorbent assay for detection of clopidol residues in chicken tissues.

BACKGROUND: Clopidol is mainly used for the prevention and treatment of coccidiosis, which poses a serious potential hazard to public health, in veterinary medicine. The aim of this study was to prepare monoclonal antibodies (mAbs) against clopidol (CLOP) and develop an immunoassay for detecting CLOP residues in chicken tissues. After derivation, CLOP hapten was conjugated to carrier proteins to synthesize the artificial antigen, and immunized Balb/C mice were employed to screen mAbs. RESULTS: A sensitive hybridoma named C1G3 was screened out and two indirect competitive enzyme-linked immunosorbent assay (icELISA) standard curves were established. For the traditional two-step assay the linear range was from 0.06 to 98 ng mL(-1) , with half-maximal inhibitory concentration (IC50 ) and limit of detection (LOD) values of 2.76 ng mL(-1) and 0.03 ng mL(-1) respectively, while the rapid one-step icELISA had a working range from 0.08 to 102 ng mL(-1) , with IC50 and LOD values of 3.52 ng mL(-1) and 0.03 ng mL(-1) respectively. It was also indicated that a 10-fold dilution in chicken muscles gave an inhibition curve almost the same as that obtained in phosphate-buffered saline. When applied to spiking tests in chicken samples, the correlation coefficient (R(2) ) between concentrations added and measured was 0.9534. CONCLUSION: The results of this study suggest that the immunoassay described is a promising alternative for screening CLOP residues in biological matrices and is suitable for routine diagnostics.

Photophysical and electrochemical properties of donor-acceptor conjugated oligomers based on 3,4-ethylenedioxythiophene and deficient rings.

The photophysical and electrochemical properties of four novel donor-accepter (D-A) conjugated oligomers a-d based on 3,4-ethylenedioxythiophene (EDOT) and electrondeficient heterocycle rings were investigated. The UV-vis absorption spectroscopy, fluorescence emission spectroscopy and cyclic voltammertry studies suggest that the oligomers are expected to provide enhanced charge-transporting properties for the development of efficient electroluminescent materials. Furthermore, the third-order nonlinear optical (NLO) measurements made by Z-scan technique indicate that they have good third-order NLO response and are desired materias for fabricating nonlinear photonic devices. In the solid state of these oligomers, a strong tendency of self-assembled structure was also revealed by X-ray diffraction (XRD) patterns in powder.

pH-induced fabrication of DNA/chitosan/alpha-ZrP nanocomposite and DNA release.

With positively charged chitosan as an intermediary, herring sperm DNA was intercalated into the interlayer galleries of negatively charged alpha-ZrP to form DNA/chitosan/alpha-ZrP ternary hybrids at pH 5.5. Fourier-transform IR, x-ray diffraction and scanning electron microscopy confirmed not only the coexistence of DNA, chitosan and alpha-ZrP in the composite but also the layered composite structure with an interlayer distance of 4.25 nm. Circular dichroism (CD) and UV spectroscopic studies disclosed that the restraint of DNA by the layered alpha-ZrP favors stabilization of the double-helical conformation of DNA and enhances the denaturation temperature. The intercalated DNA can be effectively released from the ternary nanocomposites at pHs higher than 6.5, and the released DNA displayed a similar CD spectrum to that of free DNA. The current research displays the promising potential to obtain a non-viral gene vector by intercalating DNA into negatively charged inorganic layered materials in the presence of a positively charged intermediary.

MiR-203a-3p regulates the biological behaviors of ovarian cancer cells through mediating the Akt/GSK-3ß/Snail signaling pathway by targeting ATM.

OBJECTIVE: To investigate whether miR-203a-3p can regulate the biological behaviors of ovarian cancer cells by targeting ATM to affect the Akt/GSK-3ß/Snail signaling pathway. METHODS: The expression levels of miR-203a-3p and ATM were detected by qRT-PCR, immunohistochemical staining and Western blotting in ovarian cancer tissues and adjacent normal tissues obtained from 152 subjects. A dual-luciferase reporter gene assay was performed to verify the relationship between miR-203a-3p and ATM. Human ovarian cancer cell lines (A2780 and SKOV3) were used to generate the Blank, miR-NC, miR-203a-3p mimic, Control siRNA, ATM siRNA, and miR-203a-3p inhibitor + ATM siRNA groups. The biological behaviors of ovarian cancer cells were evaluated by CCK-8, wound healing, and Transwell invasion assays, annexin V-FITC/PI staining and flow cytometry. The levels of Akt/GSK-3ß/Snail pathway-related proteins were assessed by Western blotting. RESULTS: Ovarian cancer tissues showed lower miR-203a-3p levels and higher ATM levels than adjacent normal tissues, both of which were associated with the FIGO stage, grade and prognosis of ovarian cancer. As confirmed by a dual-luciferase reporter gene assay, miR-203a-3p could target ATM. Furthermore, the miR-203a-3p mimic had multiple effects, including the inhibition of the proliferation, invasion and migration of A2780 and SKOV3 cells, the promotion of cell apoptosis, the arrest of the cell cycle at the G1 phase, and the blockage of the Akt/GSK-3ß/Snail signaling pathway. ATM siRNA had similar effects on the biological behaviors of ovarian cancer cells, and these effects could be reversed by a miR-203a-3p inhibitor. CONCLUSION: miR-203a-3p was capable of hindering proliferation, migration, and invasion and facilitating the apoptosis of ovarian cancer cells through its modulation of the Akt/GSK-3ß/Snail signaling pathway by targeting ATM, and therefore it could serve as a potential therapeutic option for ovarian cancer.

Analysis of 19-nortestosterone residue in animal tissues by ion-trap gas chromatography-tandem mass spectrometry.

A rapid sample treatment procedure for the gas chromatography-tandem mass spectrometry (GC-MS) determination of 19-nortestosterone (19-NT) in animal tissues has been developed. In our optimized procedures, enzymatic hydrolysis with ß-glucuronidase from Escherichia coli was performed in an acetate buffer (pH 5.2, 0.2 mol/L). Next, the homogenate was mixed with methanol and heated at 60 °C for 15 min, then placed in an ice-bath at -18 °C for 2 h. After liquid-liquid extraction with n-hexane, the analytes were subjected to a normal-phase solid phase extraction (SPE) C18 cartridge for clean-up. The dried organic extracts were derivatized with heptafluorobutyric anhydride (HFBA), and then the products were injected into GC-MS. Using electron impact mass spectrometry (EI-MS) with positive chemical ionization (PCI), four diagnostic ions (m/z 666, 453, 318, and 306) were determined. A standard calibration curve over the concentration range of 1-20 ng/g was reached, with Y=467084X-68354 (R²=0.9997) for 19-NT, and the detection limit was 0.3 ng. When applied to spiked samples collected from bovine and ovine, the recoveries ranged from 63% to 101% with relative standard deviation (RSD) between 2.7% and 8.9%. The procedure is a highly efficient, sensitive, and more economical method which offers considerable potential to resolve cases of suspected nandrolone doping in husbandry animals.

Development of an indirect competitive ELISA for simultaneous detection of enrofloxacin and ciprofloxacin.

Modified 1-ethyl-3-(3-dimethylaminopropy) carbodiimide (EDC) method was employed to synthesize the artificial antigen of enrofloxacin (ENR), and New Zealand rabbits were used to produce anti-ENR polyclonal antibody (pAb). Based on the checkerboard titration, an indirect competitive enzyme-linked immunosorbent assay (ELISA) standard curve was established. This assay was sensitive and had a linear range from 0.6 to 148.0 µg/kg (R(2) = 0.9567), with the half maximal inhibitory concentration (IC(50)) and limit of detection (LOD) values of 9.4 µg/kg and 0.2 µg/kg, respectively. Of all the competitive analogues, the produced pAb exhibited a high cross-reactivity to ciprofloxacin (CIP) (87%), the main metabolite of ENR in tissues. After optimization, the matrix effects can be ignored using a 10-fold dilution in beef and 20-fold dilution in pork. The overall recoveries and coefficients of variation (CVs) were in the ranges of 86%-109% and 6.8%-13.1%, respectively. It can be concluded that the established ELISA method is suitable for simultaneous detection of ENR and CIP in animal tissues.

Structures and energies of the radicals and anions generated from chlorpyrifos.

The radicals and anions generated from chlorpyrifos by removing a hydrogen atom have been investigated using the hybrid density functional B3PW91 method. The results show that all the radicals have been classified as three groups and their stability order is methylene (radical 1, 3, 5, and 7) > methyl (radical 9, 11 and 13) > ring (15); the anions have the relative energetic order: methyl > methylene > ring. Moreover, some decomposition reactions are also reported. The large HOMO-LUMO gaps indicate that both radicals and anions are predicted to be high-kinetic stable molecules. We also find that radicals 9, 11 and 13 have the highest AEAs and anions 2, 4 and 6 have higher VDEs. Additionally, natural population analysis charges show that there is the lowest Deltaq (0.14) for the C7 and C9 atoms. We hope that our theoretical results may provide a reference for further experiment and practical application.