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New enrofloxacin microspheres were formulated, and their physical properties, lung-targeting ability, and tissue distribution in rats were examined. The microspheres had a regular and round shape. The mean diameter was 10.06 microm, and the diameter of 89.93% of all microspheres ranged from 7.0 microm to 30.0 microm. Tissue distribution of the microspheres was evaluated along with a conventional enrofloxacin preparation after a single intravenous injection (7.5 mg of enrofloxacin/kg bw). The results showed that the elimination half-life (t(1/2beta)) of enrofloxacin from lung was prolonged from 7.94 h for the conventional enrofloxacin to 13.28 h for the microspheres. Area under the lung concentration versus time curve from 0 h to infinity (AUC(0-infinity)) was increased from 11.66 h.microg/g to 508.00 h.microg/g. The peak concentration (Cmax) in lung was increased from 5.95 microg/g to 93.36 microg/g. Three lung-targeting parameters were further assessed and showed that the microspheres had remarkable lung-targeting capabilities.

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Different compounds can induce stress response by targeting specific genes. Studies related to elucidating the detoxification and adaptive responses of proteins like glutathione-s-transferase (GST) can be helpful in better understanding toxicity. Roxarsone and arsanilic acid, which have been exhaustively used as animal and poultry feed additives, pose a threat to the environment and human health. GST enzyme bioassay revealed fluctuations in response to different concentrations of roxarsone and arsanilic acid at different time intervals. The highest GST enzyme activity (40.51%) was observed on day 15 of treatment with roxarsone. On the other hand, arsanilic acid caused the maximum enzyme activity (52.11%) on day 10 of treatment. During this study, the full-length gene sequence of GST, having the size 984 bp (Genbankno. HQ693699), was achieved from Eisenia fetida and established as a biomarker to assess the toxicity of roxarsone and arsanilic acid. The deduced protein has a computed molecular mass of 23.56 kDa and a predicted isoelectric point of 9.92. Quantitative real-time PCR revealed significant differential gene expression in response to roxarsone and arsanilic acid treatment as compared with control treatment. Roxarsone caused the highest gene expression of 7.0-fold increase over control on day 15 of treatment, whereas arsanilic acid resulted in the highest gene expression reaching to 14.56-fold as compared with control. This study is helpful in understanding the role of GST as a potential biomarker for chemicals like roxarsone and arsanilic acid, which can pollute the food chain.

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The chemical structures of mequindox related metabolites in chicken plasma had been investigated using high performance liquid chromatography combined with linear ion trap quadrupole(LC-ESI/LTQ) and high performance liquid chromatography combined with ion trap-time of flight-mass spectrometry (LC-ESI/IT-TOF).Samples were separated by Hypersil BDS C_(18) and symmetry Shield columns, respectively, and 0.01% formic acid aqueous(A) and methanol(B) were used as mobile phase with gradient elution.Electros pray ionization mass spectrometric(ESI) source was used and operated in positive ion mode.When chickens were orally administered with mequindox at dosage of 20 mg/kg, blood samples were collected from the brachi al vein.Mequindox and its metabolites were extracted by the mixture of acetonitrile and acetoacetate (3:2, V/V).After solvent evaporated, the residue was dissolved in 30% methanol aqueous and the solution was detected by LC/IT-TOF MS and LC-ESI/LTQ.The molecule weight from LC-ESI/IT-TOF was analyzed by software Shimadzu's Composition and the mass chromatogram from LC-ESI/LTQ was analyzed by software Xcalibur 2.0.7.According to the molecular weight and MS~n data, referring the metabolic reaction rules, five chemical structures of mequindox related metabolites in chicken plasma were identified.Metabolites (M1-M4) were synthesized to verify the structure of metabolites.The metabolites are 3-methyl-2-(1-hydroxy) ethyl-qui-noxaline-N~1,N~4-dioxide(Ml), 3-methyl-2-(1-hydroxy) ethyl-quinoxaline-N~4-oxide(M2), 3-methyl-2-acetyl-quinoxaline-N~4-oxide, 3-methyl-2-acetyl-quinoxaline (M4), 3-hydroxymethyl-2-(1-hydroxy) ethyl-quinoxa-line-N~1,N~4-dioxide (M5).

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The PCR product of PvpA gene was cloned into prokaryotic expression vector pET41a(+) and the recombinant expression vector was then transformed into E.coli DH5a after identified by restriction enzyme digestion and PCR.The positive recombinant plasmid was transformed into E.coli BL21 (D3) and induced to express PvpA protein.The obtained protein was analyzed by SDS-PAGE and Western blotting,purified by Ni-NTA affinity chromatography.The results showed that the purified PvpA fusion protein was obtained successfully.The expressed protein reacted to the high anti-PvpA immune serum from rabbit specially by western blotting.This study would be helpful to established a new diagnostic method for the detection of M.gallisepticum.