A Bama Minipig Model of Laryngopharyngeal Reflux and the Change of Laryngopharyngeal Mucosal Ultrastructure

BACKGROUND/AIMS: To establish an animal model of laryngopharyngeal reflux (LPR) and study the effect of LPR on the laryngopharyngeal mucosal ultrastructure. METHODS: Ten Bama minipigs were randomly divided into control group and stent group. Every pig underwent endoscope, and baseline pH was monitored for 4 hours at laryngopharynx and distal esophagus, then specimens from laryngopharyngeal mucosa were biopsied. For the control group, these procedures were repeated on the 14th day. In the stent group, a custom-designed esophageal stent suit was implanted into esophagus, laryngopharyngeal and distal esophageal pH monitoring lasted for 2 hours, then stent suit was removed 3 days later. At last, the same procedures were done as the control group on the 14th day. Specimens were observed under transmission electron microscope to measure the intercellular space and desmosome number. RESULTS: In the control group, there was no laryngopharyngeal reflux on the first day and 14th day. Before the stent was implanted, there was also no laryngopharyngeal reflux in the stent group. In both 2 hours and 14 days after stent implantation, the num -ber of reflux, reflux time, and percentage time of pH < 4.0 were significantly increased (P < 0.05) in the stent group. There was no difference in intercellular space and desmosomes in the control group between baseline and 14th day. In the stent group, intercellular space of laryngopharyngeal mucosa was significantly increased (0.37 mum vs 0.96 mum, P = 0.008), and the number of desmosomes was significantly decreased (20.25 vs 9.5, P = 0.003). CONCLUSIONS: A Bama minipig model of LPR was established by implanting a custom-designed stent suit. LPR might destroy the laryngophar yngeal mucosal barrier.

Determination of PA-824 in Rat Plasma by HPLC-MS/MS and Application in Pharmaco-kinetic Study / 医药导报

Objective To develop an HPLC-MS/ MS method for quantitative determination of PA-824 in rat plasma and to study the pharmacokinetics of PA-824 in rat after oral administration. Methods An HPLC-MS/ MS method was developed and validated for determination of PA-824 in rat plasma using metronidazole as internal standard.The proteins in plasma samples were precipitated with methanol,and PA-824 was enriched for analysis by HPLC-MS/ MS.An Inertsil? ODS3 C18 column (150 mm×4.6 mm,5 μm) was applied with mobile phase composed of methanol- 0.03% triethylamine (TEA) in water (90:10) ,at a flow rate of 0. 5 mL ? min-1 and column temperature of 30 ℃ . Quantitation was performed on a triple quadrupole mass spectrometer applying electrospray ionization technique and operating in multiple reaction monitoring (MRM) and positive ion mode with transitions at 360.1/ 175.0 for PA-824 and 172.0/ 128.0 for metronidazole.The concentration of PA-824 in plasma was tested after oral administration at various time points and the data were processed with software DAS.2.0. Results The standard calibration curve for spiked rat plasma containing PA-824 was linear over the range of 0. 1 - 10. 0 μg?mL-1 . The recoveries obtained for PA-824 were greater than 92.13%.Intra-day and inter-day coefficient of variation were less than 6.6%.After oral administration,the main pharmacokinetic parameters were AUC(0-t) : ( 3 297. 503 ± 320. 958) mg ? L-1 ? min-1 , AUC(0-∞ ) :(3 558.315±338.860)mg?L-1?min-1 ,tmax:(360.000±64.143)min,Cmax:(3.5±0.3)μg?mL-1 . Conclusion The method is rapid,accurate,simple,and successfully applied in a pharmacokinetic study of fixed dose oral administration of PA-824 in rats.