ABSTRACT
Objective To evaluate the effect of different preparation processes on preparation of the glial cell line-derived neurotrophic factor(GDNF)loaded microspheres and observe the biological activity of GDNF.Methods With polylactide-co-glycolide(PLGA)as the coating material,the GDNF-loaded microspheres were prepared by using double emulsion(W1/O/W2).Two-factor factorial design variance analysis was done to analyze the effects of the composition proportion of lactic acid(LA)and glycolic acid(GA)in PLGA and the stirring speed of multiple emulsion on particle size,entrapment efficiency,burst release and in vitro release characteristics of the GDNF-loaded microspheres.PC-12 bioassay was employed to detect the biological activity of the released GDNF so as to determine the optimal preparation process.Results The composition proportion of PLGA could affect the microspheres'burst release(P ＜ 0.05),with no effect on particle size and entrapment efficiency.with the higher.With higher proportion of GA,the release speed of GDNF in the microspheres was increased.When the stirring speed of multiple emulsion was increased from 1 000 r/min to 3 000 r/min,the particle size of the microspheres was decrease significantly(P ＜ 0.01),the burst release was increased markedly(P ＜ 0.01)and the in vitro release rate was accelerated.The activity of GDNF in the microspheres could last for about 20 days at 37℃,which was 10 days longer than that of single GDNF.Conclusions Double emulsioncan prepare the GDNF-loaded microspheres with high entrapment efficiency and suitable in vitro release time.In the meantime,the microspheres can extend the validity of GDNF.
ABSTRACT
Objective To investigate the anatomical features, operative method and efficacy of internal fixation in the treatment of iutra-articular fractures of caleaneum via the sinus tarsi approach. Methods The pathway, branches distribution and anastomosis of perforating descending branch of peroneal artery were observed on 18 adult cadaveric lower limbs. A sinus tarsi approach was designed. From July 2001 to January 2008, 71 intra-articular calcaneal fractures in 68 patients were treated with open reduction and internal fixation via sinus tarsi approach at lateral sides of calcaneus. According to the Sanders classification, there were 26 type Ⅱ fractures, 32 type Ⅲ fractures and 13 type Ⅳ fractures. Results All patients were followed up for a mean period of 39.3 months (13-85 months), and the fractures were completely healed. There was a significant difference in the length, width and height of the calcaneus, Bohler angle and Gissane angle before and after operation (P < 0.01). According to Maryland Foot Score, the operative effect was excellent in 33 feet, good in 29 feet, fair in 6 feet and poor in 3 feet. Conclusion Open reduction and internal fixation via sinus tarsi approach is an effective method for minimally invasive treatment of intraarticular fractures of the calcaneus, with the advantages of good clinical results and causing minimal damage to soft tissues.