Preparation and evaluation of enrofloxacin microspheres and tissue distribution in rats

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.

Identification of Mequindox and Its Metabolites by High Performance Liquid Chromatography Combined with Ion Trap-Time of Flight-Mass Spectrometry / 分析化学

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).

Prokaryotic expression,purification and polyclonal antibody preparation of putative cytadhesin protein (PvpA) of Mycoplasma gallisepticum / 中国兽医学报

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.