Objective:To prepare the multilayer alginate chitosan microspheres loading vascular endothelial growth factor (VEGF) and vancomycin (VAN), and to study in vitro release characteristics.Methods:The microspheres were prepared by emulsion cross-linking and self-assembly techniques.The effects of sodium alginate concentration, calcium chloride concentration, oil/water ratio and span80 concentration on the entrapment efficiency(EE) and drug loading(DL) of VEGF and VAN were investigated by orthogonal experimental design to optimize the preparation process.The surface morphology and particle size of microspheres were observed by scanning electron microscope (SEM).Self-assembly was detected by Fourier transform infrared spectroscope (FTIR).The EE, DL and in vitro release of VEGF and VAN were detected by ELISA double antibody sandwich method and ultraviolet spectrophotometry,and the cumulative release curve was drawn.Results:The prepared microspheres were yellowish brown powder.The SEM results showed that the microspheres were spherical, the surface was smoothy, and the dispersity was better.The average particle size was about 50 μm.Sodium alginate concentration of 1.0 g·mL-1, CaCl2 concentration of 8 g·mL-1, oil to water ratio of 3∶1, and span80 concentration of 2% were the best formula.The EE of VEGF and VAN were 49.63% and 16.67%, respectively.In vitro, the cumulative release last 16.5 d and 12.5 d respectively and the amount reached up to 95%.Conclusion:The multilayer alginate chitosan microspheres loading VEGF and VAN present several advantages, such as smaller particle size, higher EE and better controlled release.

Objective:To investigate the influence of multilayer alginate chitosan sustained-release microspheres loading vascular endothelial growth factor(VEGF) and vancomycin in the proliferation and osteogenic differentiation of human plaacenta-derived mesen chymal stem cells(HPMSCs),and to provide theoretical basis for its clinical application in the repair of bone defect.Methods:The microspheres were prepared based on the previous research and HPMSCs were co-cultured with drug (VEGF/vancomycin)-loaded microspheres (drug-loaded microspheres+HPMSCs group), non-drug loaded microspheres (microspheres+HPMSCs group) and without any microspheres (HPMSCs group).Then the proliferation rate of HPMSCs was identified by CCK-8 kit.The osteogenic differentiation potential of HPMSCs was detected by Alizarin red staining and alkaline phosphatase (ALP) kit when the HPMSCs had been co-cultured with drug loaded microspheres in osteogenic medium (HPMSCs+drug-loaded microspheres+induction group), non-drug loaded microspheres in osteogenic medium (HPMSCs+microspheres+induction group), without any microspheres in osteogenic medium (HPMSCs+induction group) and without any micropheres in normal medium (HPMSCs+PBS group) for 21 d.Results:Compared with HPMSCs group,the proliferation rates of HPMSCs in drug-loaded microspheres+HPMSCs and microspheres+HPMSCs groups had no significant changes (P>0.05).The calcium deposition in HPMSCs+drug-loaded microspheres+induction group was more than those in microspheress+HPMSCs+indution group and HPMSCs+induction group after Aalizarin red staining;the ALP activity in drug-loaded microspheres+HPMSCs+indution group was higher than those in microspheres+HPMSCs+indution group and HPMSCs+induction group (P<0.05),and the ALP activity in microspheres+HPMSCs+induction group was higher than that in HPMSCs+induction group(P<0.05).Conclusion:The sustained-release microspheres loading VEGF and vancomycin have no significant effect on the proliferation activity of HPMSCs and the microspheres could stimulate the osteogenic differentiation of HPMSCs.

Objective:To make the fixed partial dentures with different materials and the magnetic resonance imaging (MRI)examination of head and neck was carried out to investigate the effects of fixed partial dentures on MRI.Methods:A qualified volunteer was recruited,who was conventionally restored using fixed partial denture. Co-Cr alloy,Au-Pt alloy and Zirconia were chosen as the inner crown materials,respectively.Three kinds of fixed partial dentures were put into the mouth of patient,and 2 kinds of MRI scan sequences (T1-TSE and T2-TSE) were performed.The scanning images without restorations were used as controls.The change of shape,image signal and involving layers of artifacts of different materials in three groups were observed.The maximum diameter of artifact of three materials in coronal, sagittal and axial images were detected. The safeties of fixed partial dentures were observed. Results: The artifacts were found in all the restorations and showed the changes of strengthen and weaken of the signal and the changs of shapes of images.The range of artifacts was the largest in the involved central plane and varied in sagittal,coronal and axial images. The number of involving layers of artifacts in Co-Cr alloy group was significantly more than those in Au-Pt alloy and Zirconia groups;the artifacts were limited in the repaired lateral maxillofacial region without the cervical spine and head region involvement.The artifacts in Co-Cr alloy group involved or slightly involved in all adjacent tissues,and the artifacts in Au-Pt alloy and Zirconia groups only slightly affected the mandibular teeth,lingual muscles and maxillary crowns.The maximum diameter of artifacts in Co-Cr alloy group was larger than those in Au-Pt alloy group and Zirconia group (P <0.05). No displacement was found in the prosthesis,and the patient had no discomfort.Conclusion:The artifact of the fixed partial denture can be seen in MRI examination.Co-Cr alloy or zirconia can significantly reduce the effect of artifact.Fixed adhesive prosthesis in mouth does not affect the safety of MRI examination.

Letrozole,a third generation non-steroidal aromatase inhibitor,has been approved for the treatment of breast cancer in women.In recent years,it has been used in the field of growth and development in children,such as childhood dwarfism,somatic delayed pubertal growth and precocious puberty,but the long-term effects on liver and kidney function,lipid metabolism,reproductive function and bone metabolism are unclear.Studies have shown that letrozole can cause abnormal testicular morphology,changes in seminiferous tubules and interstitial tissues,reduce bone density,affect the bal-ance of bone metabolism,and cause cognitive impairment and apoptosis of nerve cells.The mecha-nism of reproductive toxicity of letrozole may be related to its influence on the development and matura-tion of testicular cells,the expression of sex hormones and gonadotropins in vivo,and the distribution and expression of estrogen receptors in testicular tissues.The mechanism of bone metabolic toxicity is related to its increase in the proliferation and differentiation of osteoclasts induced by receptor activator of NF-κB ligand,as well as the increase of apoptosis,oxidative stress and NF-κB activity of osteo-blasts.The mechanism of cognitive toxicity is related to its regulation of classical and nonclassical effects of the hippocampus,reduction of glutamate uptake by astrocytes,and reduction of L-type calcium channel blockade of caspase 3 activation.This article is to provide reference for safe and effective use of letrozole in clinical pediatrics.