OBJECTIVE: To optimize the preparation technology of poly(lactide-co-glycolide) (PLGA) microspheres loaded with ropivacaine (ROP-PLGA-MS) and study their powder particle characteristics and in vitro release characteristics. METHODS: ROP-PLGA-MS was prepared with PLGA as carriers using the water-in-oil-in-water(W/O/W) emulsion solvent evaporation method. The micromeritic characteristics of ROP-PLGA-MS,such as the particle size,loading and entrapment efficiency were taken as indexes for evaluation,and the preparation technology was optimized by orthogonal design. Its dissolution characteristics in vitro were studied. RESULTS: The prepared microspheres were spherical with smooth surfaces,with an average particle size of (2.525?0.047) ?m and over 80% falling in the range of 1.8～5.0 ?m. The encapsulation efficiency was (58.05?1.169)% and the drug loading efficiency was (6.067 ?0.312)%. The in vitro release curves of ropivacaine microspheres could be fitted with Higuchi equation. The accumulated release percentage of which was 82 % in 192 h,and t1/2=60.16 h. CONCLUSION: ROP-PLGA-MS has obvious sustained release.

Objective To evaluate the relationship between extracellular signal-regulated kinase (ERK)and ketamine-induced apoptosis in rat hippocampal neurons.Methods Sprague-Dawley rats at 18 days of gestation were anesthetized.The fetal rats were obtained under the sterile condition and decapitated.The hippocampal neurons were isolated and primarily cultured for 5 days,and were seeded in 6-well plates (2 ml/well) or in 96-well plates (100μl/well) at a density of 5 × 105/ml.The cells were randomly divided into 4 groups (n =18 each):control group (group C),fibroblast growth factor (FGF-2,an ERK agonist) group (group F),ketamine group (group K) and FGF-2 + ketamine group (group FK).The cells were cultured in the plain culture medium in group C.FGF-2 50 ng/ml was added to the culture medium in group F.Ketamine was added to the culture medium in group K.FGF-2 50 ng/ml was added to the culture medium at 20 min before ketamine 100 μmol/L was added in group FK.The phosphorylation of ERK in hippocampal neurons was detected by Western blot at 10 min after treatment.At 24 h after treatment,the neuronal apoptosis was detected by Hoechst33342/PI staining,and the cell survival rate was detected by MTT assay.The apoptosis rate was calculated.Results Compared with group C,the phosphorylation of ERK in hippocampal neurons and the cell survival rate was significantly decreased and the apoptosis rate was increased in K and FK groups (P ＜ 0.05).There was no significant difference in the parameters mentioned above between F and C groups (P ＞ 0.05).The phosphorylation of ERK in hippocampal neurons and the cell survival rat was significantly higher and the apoptosis rate was lower in group FK than in group K (P ＜0.05).Conclusion Ketamine induces apoptosis in rat hippocampal neurons by inhibiting activation of ERK in hippocampal neurons.

Objective To investigate the role of nuclear factor-kappa B (NF-κB)signaling pathway in propofol-induced suppression of up-regulation of inducible nitric oxide synthase (iNOS) gene expression in LPSstimulated RAW264.7 cells.Methods RAW264.7 cells were purchased from cell bank of Chinese Academy of Sciences and cultured in DMEM culture medium containing 10％ fetal bovine serum.The cells were seeded in 6 cm diameter dishes (3 ml/dish) or in 6-well plates (2 ml/well) with a density of 5 × 105/ml and randomly divided into 3 groups ( n =18): normal control group (group C),group LPS (group L)and group LPS + propofol (group LP).The cells were incubated with LPS 1 μg/ml in groups L and LP.Propofol 50μmol/L was added to the culture medium at 2 h before LPS in group LP.Cells were harvested at 30 min after being stimulated with LPS.Phosphorylation of IκB kinase(p-IKK) and NF-κB activity were detected by Western blot.The expression of iNOS mRNA was determined after 6 h exposure of the cells to LPS.Results LPS significantly up-regulated the expression of p-IKK and iNOS mRNA and increased NF-κB activity in group L as compared with group C.Propofol pretreatment significantly attenuated the effects of LPS on p-IKK,iNOS mRNA expression and NF-κB activity.Conclusion NF-κB signaling pathway is involved in the propofol-induced suppression of up-regulation of iNOS mRNA expression in LPS-stimulated RAW264.7 cells.

Objective:To report a case of germinated teeth of the left mandibular second molar diagnosed by cone-beam CT (CBCT), and to investigate its differential diagnosis, pathogenesis, and the application value of CBCT in the diagnosis of oral and maxillofacial diseases.Methods:One case of germinated teeth of the left mandibular second molar diagnosed according to oral general examination ad CBCT findings in Zhenjiang Stomatological Hospital, China in March, 2019 was included in this study. The characteristics and differential points of supernumerary cusp, fused teeth, geminated teeth and concresence of teeth were analyzed based on literatures.Results:CBCT examination showed that the number of mandibular dentition teeth was normal, there was a large area of low-density transmission area around the root of the left mandibular second molar. Three-dimensional reconstruction results revealed that the suspected supernumerary teeth were fused with the root of the left mandibular second molar. Sagittal projections showed that the suspected supernumerary teeth were located in the buccal side of the left mandibular second molar. Axial projections showed three separate root canal orifices at the level of pulp chamber floor, and the dentin of the two was connected. The suspected supernumerary teeth had an independent pulp cavity and a clear root canal, and fused with the distal root canal of the left mandibular second molar in the middle of the root to form a root canal. A "Y"-shaped structure was displayed on the sagittal projections. CBCT showed that the left mandibular second molar was a fused root. Based on oral clinical examination, the left mandibular second molar was confirmed to be a germinated tooth.Conclusion:CBCT is one of the most important means of oral auxiliary examination. It has significant advantages in the diagnosis of tooth abnormalities. It can help clinicians to make correct diagnosis and choose the appropriate treatment scheme. It has certain clinical significance and innovation.