[Analysis of related risk factors for the refracture of adjacent vertebral body after percutaneous kyphoplasty].

OBJECTIVE: To investigate the risk factors of vertebral refracture after percutaneous kyphoplasty (PKP) for osteoprotic vertebral compression fractures (OVCFs), and to provide reference for clinical prevention. METHODS: A retrospective analysis of 228 OVCFs patients who met the inclusion criteria admitted from November 6, 2013 to December 14, 2018. There were 35 males and 193 females, with a male-to-female ratio of 3∶20, and aged 58 to 91 years with an average of (69.70±7.03) years. All patients were treated with PKP and had complete clinical data. According to whether refracture occurred after operation, they were divided into refracture group (24 cases) and non refracture group (204 cases). Factors that may be related to refracture (including gender, age, surgical segment, number of vertebral bodies in the surgical segment, whether combined with degenerative scoliosis, whether anti-osteoporosis treatment) were included in the univariate analyses, and the single factor analysis of statistically significant risk factors was carried out with multiple Logistic regression analysis to further clarify the independent risk factors for vertebral body refracture after PKP. Survival analysis was performed using the time of vertebral refracture after PKP as the end time of follow up, the occurrence of refracture after PKP as the endpoint event, and the presence or absence of degenerative lateral curvature as a variable factor. RESULTS: All 228 patients were followed up for 1.8 to 63.6 months with an average of (28.8±15.6) months, and the refracture rate was 10.5%(24/228). There were statistically significant differences between two groups in age, number of operative vertebral bodies, whether combinedwith degenerative scoliosis and whether anti osteoporosis treatment (P<0.05). Univariate Logistic regression analysis showed that the number of vertebral bodies in the surgical segment and whether combined with degenerative scoliosis may be risk factors for refracture after PKP. Multiple Logistic regression analysis of the above possible risk factors showed that combined scoliosis was an independent risk factor for vertebral refracture of the vertebral body. Survival analysis showed that the mean survival time was 42.1 months, the P value was 0.00, and the mean 95% confidence interval was 34.4-49.7 months, indicating that the combination of degenerative lateral bending might be related to the occurrence of refracture. CONCLUSION: Combined scoliosis is an independent risk factor for refracture after OVCFs vertebroplasty, and it is also a possible high-risk factor for refracture after surgery.

Alpha-tocopheryl polyethylene glycol succinate-emulsified poly(lactic-co-glycolic acid) nanoparticles for reversal of multidrug resistance in vitro.

Multidrug resistance (MDR) is one of the factors in the failure of anticancer chemotherapy. In order to enhance the anticancer effect of P-glycoprotein (P-gp) substrates, inhibition of the P-gp efflux pump on MDR cells is a good tactic. We designed novel multifunctional drug-loaded alpha-tocopheryl polyethylene glycol succinate (TPGS)/poly(lactic-co-glycolic acid) (PLGA) nanoparticles (TPGS/PLGA/SN-38 NPs; SN-38 is 7-ethyl-10-hydroxy-camptothecin), with TPGS-emulsified PLGA NPs as the carrier and modulator of the P-gp efflux pump and SN-38 as the model drug. TPGS/PLGA/SN-38 NPs were prepared using a modified solvent extraction/evaporation method. Physicochemical characterizations of TPGS/PLGA/SN-38 NPs were in conformity with the principle of nano-drug delivery systems (nDDSs), including a diameter of about 200 nm, excellent spherical particles with a smooth surface, narrow size distribution, appropriate surface charge, and successful drug-loading into the NPs. The cytotoxicity of TPGS/PLGA/SN-38 NPs to MDR cells was increased by 3.56 times compared with that of free SN-38. Based on an intracellular accumulation study relative to the time-dependent uptake and efflux inhibition, we suggest novel mechanisms of MDR reversal of TPGS/PLGA NPs. Firstly, TPGS/PLGA/SN-38 NPs improved the uptake of the loaded drug by clathrin-mediated endocytosis in the form of unbroken NPs. Simultaneously, intracellular NPs escaped the recognition of P-gp by MDR cells. After SN-38 was released from TPGS/PLGA/SN-38 NPs in MDR cells, TPGS or/and PLGA may modulate the efflux microenvironment of the P-gp pump, such as mitochondria and the P-gp domain with an ATP-binding site. Finally, the controlled-release drug entered the nucleus of the MDR cell to induce cytotoxicity. The present study showed that TPGS-emulsified PLGA NPs could be functional carriers in nDDS for anticancer drugs that are also P-gp substrates. More importantly, to enhance the therapeutic effect of P-gp substrates, this work might provide a new insight into the design of pharmacologically inactive excipients that can serve as P-gp modulators instead of drugs that are P-gp inhibitors.