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<p><b>OBJECTIVE</b>To synthesize a biodegradable and minimally cytotoxic amphiphilic block copolymer of PLGA-b-(PEI-co- PEG) and study its micellization behavior.</p><p><b>METHODS</b>PLGA was synthesized by ring-opening polymerization. The cross-linked copolymer of PEI-co-PEG was synthesized from the low-molecular-weight polyethyleneimine (PEI, 1800 D) and hydrophilic poly(ethylene glycol) (PEG, 2000 D). PLGA-b-(PEI-co-PEG) was synthesized by dehydration condensation reaction of PLGA and water soluble PEI-co-PEG. The biodegradability of PEI-co-PEG was evaluated according to the molecular weight change after incubation at 37 ℃ for different time. The cytotoxicity of PLGA- b-(PEI-co-PEG) and PEI-co-PEG in MCF-7 cells was determined by MTT assay. The cationic PLGA-b-(PEI-co-PEG) micelles were prepared by standard dialysis method. The particle size and Zeta potential of the micelles were measured by a Malvern laser particle size analyzer. Micelle/insulin complexes were prepared by simple mixing method and their morphology were characterized by transmission electron microscopy (TEM). The fluorescence quenching method was used to determine the stability of the micelle/insulin complexes at different salt concentrations.</p><p><b>RESULTS</b>Amphiphilic block copolymer of PLGA-b-(PEI-co-PEG) was successfully synthesized. The half-life of PEI-co-PEG degradation in PBS at 37 ℃ was about 48 h. The 50% cell inhibiting concentration (IC) of PLGA-b-(PEIco- PEG) and PEI-co-PEG in MCF-7 cells were 1375.7 μg/mL and 425.1 μg/mL, respectively. The micelles of PLGA-b-(PEI-co- PEG) (particle size: 99.5±2.61 nm, Zeta potential: 52.9±2.38 mV) were complexed with insulin electrostatic interaction and formed nanoscale micelle/insulin complexes. The dissociation rate of micelle/insulin complexes in 150 mmol/L NaCl solution was 27.6%.</p><p><b>CONCLUSIONS</b>The synthesized PEI-co-PEG shows good degradability . The cytotoxicity of PLGA-b-(PEI-co- PEG) is significantly lower than PEI-co-PEG, and PLGA-b-(PEI-co-PEG) micelle/insulin complexes have good salt- resistant stability in physiological condition.</p>
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[Objective] To explore the application of Da Vinci robot in laparoscopic pyeloplasty treatment for pediatric hydronephrosis and to improve the effect of operation and shorten the operation time effectively.[Methods] A summary and analysis was performed on the intraoperative cooperation about the clinical data of 14 pediatric hydronephrosis cases (16 sides) whom were performed RALP from November 2015 to July 2016.The intraoperative cooperation includes preoperative education,adequate preparation of surgical instruments,ensuring the normal operation of robot system before surgery and also,the proper body positions,the protection for patients,the establishment of aseptic barrier during operation as well as the maintenance of robot after operation.[Results] All procedures were performed via transperitoneal approach.Docking time was shortened from 40 to 20 min,operation time lasted (115± 38) min.One severe case presented with anastomasis stenosis even after PCN dilatation,and was redid dismembered pyeloplasty half a year later and the ultimate result was good.The other cases recovered well and the overall success rate was 93.75％.There were no robot failure caused by improper cooperation and no complications caused by improper nursing among the 14 pediatric hydronephrosis cases (16 sides) in pediatric hydronephrosis operations.[Conclusion]Da Vinci robot performed well in assisting laparoscopic pyeloplasty treatment for pediatric hydronephrosis,for it leaves light surgical trauma and short duration of operation.Adequate preoperative preparation,medical staff's formal professional technical training and professional cooperation team can not only improve the operation efficiency,but also be the key to the success of the operation.
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Objective To summarize the surgery nursing cooperation points of liver procurement of brain death contributions (DBD) donor in the uninterrupted blood flow way . Methods Complete the following preoperativepreparation such as personnel,brain death donation donor,environment ,surgical content,multiple organ repair system and other related equipments;intraoperative preparation includes surgical instruments and related equipments ,assisting intubation of arteria lienalis ,portal vein and the choledochus and the organ procurement . Result About 3 cases of donor liver procurement were successfully implemented in the interrupt blood flow way, operation time was 3~4 h,bleeding was 200~400 mL,an average of 300 mL. Conclusions Uninterrupted flow liver transplantation can protect liver function to the greatest extent , thus greatly avoids the common complication of organ transplantation.The tacit understanding surgery cooperation improves the rate of surgery successfully.
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<p><b>OBJECTIVE</b>To prepare insulin-loaded polymeric nanoparticles based on polyethyleneimine-polycaprolactone- polyethylene glycol-polycaprolactone-polyethyleneimine pentablock copolymers and evaluate its in vitro release of insulin.</p><p><b>METHODS</b>Polycaprolactone-polyethylene glycol-polycaprolactone (PCL-PEG-PCL) triblock copolymer was synthesized by ring-opening polymerization method, and the pentablock copolymer was prepared by Michael addition reaction. The copolymers obtained were characterized by Fourier-transform infrared (FT-IR) spectroscopy and (1)H-NMR and their critical aggregation concentration (CAC) was measured by fluorescence technique with pyrene as the probe. Insulin-loaded polymeric nanoparticles based on the pentablock copolymers were prepared by solvent evaporation method that exploited the cationic nature of PEI-PCL-PEG-PCL-PEI to allow the formation of ionic complexes with anionic biomolecules such as insulin. The prepared nanoparticles were further characterized by Malvern laser particle sizer and transmittion electron microscopy (TEM). The drug loading, encapsulation efficiency and in vitro release profile of the nanoparticles were analyzed using Bradford method.</p><p><b>RESULTS</b>Using copolymer PEI10K-PCL4K-PEG2K-PCL4K-PEI10K as the drug carrier, the spherical nanoparticles prepared with an optimal insulin-coplymer mass ratio of 40% allowed the maximum insulin loading of (18.63∓0.07)% and had an average particle size of 175.30∓19.51 nm. The prepared nanoparticles was capable of sustained release of insulin for as long as 48 h in vitro, and the burst release could be minimized by incorporation of PEI in the triblock copolymer.</p><p><b>CONCLUSION</b>The insulin-loaded polymeric nanoparticles based on the pentablock copolymers allow sustained release of insulin in vitro, and PEI can enhance sustained drug release and reduce burst drug release.</p>