比浊法测定氯霉素效价的研究

目的建立比浊法测定氯霉素效价,为中国药典收载比浊法测定抗生素效价做准备。方法将氯霉素标准品加适量乙醇和无菌水制成标准品储备液,以磷酸盐缓冲液稀释成4U/ml和5U/ml的溶液,分别以比浊法和管碟法测定氯霉素的效价。结果氯霉素溶液在3～8U/ml浓度范围内,浓度与吸收度呈良好的线性关系（r=0.9996）。经t检验,比浊法测定抗生素的效价结果与管碟法一致（P〉0.05）。结论本法测定氯霉素效价较为精密、正确、快速、灵敏度高、试验误差小、可信限率较低,实验重现性好,方法可取。     

Bioactivity and fluoride release of strontium and fluoride modified Biodentine

Biodentine? is a novel tricalcium silicate based material used both as a coronal dentine replacement and in pulp therapy. Its multiple use in sealing perforations, pulp capping and as a temporary restoration arises from its ability to promote dentine formation and to confer an excellent marginal seal. However, there is still room for improvement of this cement as it lacks the anticariogenic effect typically conferred by fluoride ion release as seen in glass ionomer cement based dental materials. Therefore, this study was conducted to investigate the impact of bioactive glass addition to Biodentine?.

Improved single visit management of old infected iatrogenic root perforations using Biodentine®

Aim

The aim of this retrospective observational case series study was to evaluate the middle term outcomes on endodontic management of old infected iatrogenic root perforations using Biodentine. The treatments were always concluded in a single visit, without previous medication with calcium hydroxide. Our goal was to facilitate this kind of treatments and to make them more reproducible and manageable even for a general practitioner or a student.

In vitro structural changes in porous HA/β-TCP scaffolds in simulated body fluid

Porous scaffolds of biphasic calcium phosphate (hydroxyapatite/β-tricalcium phosphate (β-TCP)) have been fabricated and changes induced both in phase composition and porous architecture by immersion in simulated body fluid (SBF) under static and orbital stirring conditions have been studied. The starting porous scaffolds exhibit a low and randomized micro- and mesoporosity, an interconnected macroporosity centered at 100 and 0.6 μm, a fractal connectivity of D = 2.981 and total percent porosity of ca. 80%. After immersion for up to 60 days the micro- and mesoporosity increase slightly, which could be attributed to dissolution of the β-TCP phase confirmed by transmission electron microscopy. The effects of the change in the porous framework with SBF immersion time favor the bioactive behavior of the tested materials, inducing a nucleation and growth of a nanocrystalline apatite phase as the interconnected macroporosity centered at 0.6 μm is reduced. The macroporosity centered at 100 μm is still stable after 60 days in SBF. Therefore, these biphasic calcium phosphate porous scaffolds combine bioactive behavior with the stability of interconnected macroporosity over large periods of soaking time in SBF under static and orbital stirring conditions.     

Biological evaluation of an apatite-mullite glass-ceramic produced via selective laser sintering

The biological performance of a porous apatite-mullite glass-ceramic, manufactured via a selective laser sintering (SLS) method, was evaluated to determine its potential as a bone replacement material. Direct contact and extract assays were used to assess the cytotoxicity of the material. A pilot animal study, implanting the material into rabbit tibiae for 4 weeks, was also carried out to assess in vivo bioactivity. The material produced by SLS did not show any acute cytotoxic effects by either contact or extract methods. There was no evidence of an apatite layer forming on the surface of the material when soaked in SBF for 30 days, suggesting that the material was unlikely to exhibit bioactive behaviour in vivo. It is hypothesized that the material was unable to form an apatite layer in SBF due to the fact that this glass-ceramic was highly crystalline and the fluorapatite crystal phase was relatively stable in SBF, as were the two aluminosilicate crystal phases. There was thus no release of calcium and phosphorus and no formation of silanol groups to trigger apatite deposition from solution within the test time period. Following implantation in rabbit tibiae for 4 weeks, bone was seen to have grown into the porous structure of the laser-sintered parts, and appeared to be very close to, or directly contacting, the material surface. This result may reflect the local environment in vivo compared to that artificially found with the in vitro SBF test and, furthermore, confirms previous in vivo data on these glass-ceramics.     

巴斯德毕赤酵母菌株分泌表达的重组骨保护素融合蛋白生物学活性的研究

目的探讨巴斯德毕赤酵母菌株分泌表达的重组骨保护素融合蛋白(recombiant humanosteoprogerin-human serum album,rhOPG-HSA)对破骨细胞的抑制效应。方法利用巨噬细胞集落刺激因子(macrophage colony stimulating factor,M-CSF)以及破骨细胞分化因子(receptor activator ofnuclear factor-kβligand,RANKL)诱导骨髓单核细胞Raw264.7分化为破骨细胞,通过抗酒石酸酸性磷酸酶(tartrate-resistant acid phosphatase,TRAP)染色和甲苯胺蓝染色法鉴定rhOPG-HSA抑制破骨细胞及其骨吸收能力。结果 rhOPG-HSA组与阴性对照组相比,Raw264.7细胞诱导3d,4d,5d后,TRAP阳性染色的破骨细胞明显减少;Raw264.7细胞与骨薄片共培养诱导10d后,骨吸收陷窝明显减少。结论 rhOPG-HSA能够抑制破骨细胞的分化及骨吸收。     

干扰素生物活性两种测定方法的比较研究

目的：摸索改进的结晶紫染色法与噻唑蓝（MTT）比色法中哪一种方法能够提高干扰素的生物学活性测定（细胞病变抑制法）结果的准确性。方法：比较在干扰素的生物学活性测定后期,采用先结晶紫染色乙醇脱色然后比色的方法（方法一）和采用加入MTT后裂解比色的方法（方法二）,经过多次比较证明哪一种方法测定结果的准确性更高。结果：采用方法二测得的多次结果之间产生的偏差较小,单次结果的可信度较高,单次测定结果的相关系数r值较大。结论：采用MTT比色法比改进的结晶紫染色法更适合应用于干扰素的生物学活性测定,可提高结果的准确性。     

热水陈化对钛种植材料表面氧化膜改性及体外生物活性评价

目的对纯钛种植材料表面氧化膜化学改性,使其活化富含羟基。方法纯钛材料经过化学处理后(NaOH或H2O2)再低温热水陈化2d。用扫描电镜、X射线衍射仪、X射线光电子能谱仪等方法对钛表面的形貌、组成结构进行了表征,并考察改性后钛表面对大鼠成骨细胞生物学影响。结果钛表面改性后呈多孔结构,热水陈化使表面氧化膜转化为富含羟基的二氧化钛层,改性后钛表面能促进成骨细胞的增殖和分化。结论化学处理后再热水陈化形成的钛表面氧化膜有良好的生物活性,表面富含的羟基可作为固定生物大分子的位点。     

Novel approach to fabricate porous gelatin-siloxane hybrids for bone tissue engineering

Porous and bioactive gelatin–siloxane hybrids were successfully synthesized by using a combined sol–gel processing, post-gelation soaking, and freeze-drying process to provide a novel kind of materials in the developments and optimization of bone tissue engineering. The pore sizes of the hybrids can be well controlled by varying the freezing temperature. The scaffolds were soaked in a simulated body fluid (SBF) up to 14 days to evaluate the in vitro bioactivity. The Ca²⁺-containing scaffolds showed in vitro bioactivity as they biomimetically deposited apatite, but the Ca²⁺-free scaffolds failed. Cytotoxicity and cytocompatibility of those scaffolds and their extracts were monitored by the MC3T3-E1 cell responses, including the cell proliferation and the alkaline phosphatase activity. It was demonstrated that appropriate incorporation of Ca²⁺ ions stimulated osteoblast proliferation and differentiation in vitro.     

海洋微生物杂环串联环(拟)肽生物活性研究进展

综述了海洋微生物杂环串联环(拟)肽生物活性研究的最新进展，在此基础上对这类环肽的潜在药用前景作了展望。