新型硼酸盐生物玻璃修复兔股骨缺损的实验研究

目的:通过观察3种生物玻璃材料在修复兔股骨缺损中的差异,来比较新型硼酸盐生物玻璃球粒与生物玻璃球粒和生物玻璃颗粒成骨能力和降解性能的差异,为其进一步应用于临床提供理论依据.方法:成年新西兰大白兔18只,双侧股骨髁部制造直径0.6 cm,深1.2 cm的贯穿型缺损.根据缺损部位植入材料的不同随机分为3组,每组6只12侧:实验对照组(A组)植入生物玻璃颗粒(The NovaBone Bioactive Glass Morsels),实验组(B组)植入生物玻璃球粒(The NovaBone Bioactive Glass Spheres),实验组(C组)植入硼酸盐玻璃球粒(The Borate Glass Morsels)三种材料,于术后第6周,第12周取材,通过大体观察,组织病理学染色来评价新型生物活性玻璃的骨缺损修复能力和降解性能.结果:第6周时,ABC组均可见有新骨生成,并且向材料内部生长.在第12周时,ABC组成骨量显著增多,而且可见成熟的骨小梁塑形.组织切片定量分析:1、成骨能力比较:术后6周,12周时,新生骨量,B组和C组多于A组(P＜0.05),且C组多于B组(P＜0.05).术后12周与6周比较,ABC三组新生骨显著增多,(P＜0.05).2、降解性能比较:术后6周,12周时,残余材料量,B组和C组少于A组(P＜0.05),且C组少于B组(P＜0.05).术后12周与6周比较,ABC三组残余材料显著减少,(P＜0.05).结论:具有球体外观设计的新型硼酸盐玻璃球粒与其它两种材料相比,不仅具有良好的成骨能力,而且具有良好降解性能,能有效的修复腔隙性骨缺损,有望成为新型骨缺损修复材料.     

Femoral Artery Complications after Diagnostic Procedures

Of 36 cases of arterial complications after femoral artery puncture 11 were excessive haemorrhage and 25 femoral artery occlusions. Soft arteries are more likely to tear than atheromatous ones, and this had occurred in 9 of the 11 patients. A high puncture, soft arteries, and a low cardiac output are important factors predisposing to thrombosis.An aggressive policy is recommended for treatment of both conditions.     

人工髋关节置换术发生股骨假体周围骨折的影响因素分析

目的:探讨人工髋关节置换术患者发生股骨假体周围骨折的相关危险因素,为临床预防和治疗提供参考资料。方法:回顾性分析2012年5月~2015年5月在我院接受人工髋关节置换术的92例患者的临床资料。根据是否发生股骨假体周围骨折将所选患者分为研究组和对照组,每组46例,比较两组患者的性别分布、年龄、骨折类型及假体固定方式等,分析影响患者发生股骨假体周围骨折的危险因素。结果:研究组患者骨折类型多为A2型,患者平均年龄、女性患者数及使用生物假体的比例均高于对照组,差异具有统计学意义(P0.05)。患者性别、年龄、骨折类型及假体固定方式是人工髋关节置换术患者发生股骨假体周围骨折的危险因素(OR=1.993、2.012和2.363,P0.05)。结论:高龄女性患者是发生股骨周围假体骨折的高危人群,骨质疏松及骨量减少是引发该并发症的主要危险因素。     

Femoral Strength after Induced Lesions in Rats (Rattus norvegicus)

Rats are a common model for the study of bone healing, with the cranium, femur, and tibia being the bones studied most frequently. This study examines noncritical-sized lesions that would allow rats to continue to bear weight without the need for fixation but that are sufficiently large to enable characterization of the healing process. We compared the femoral bone strength associated with 3 lesion sizes selected for use in future studies. Sprague–Dawley rats (age, 10 to 16 wk) were used to assess the ultimate breaking strength, stress, and break force of normal, unmanipulated femurs. We then created lesions of 3 different sizes in the mid- to distal diaphysis of the left and right femurs and characterized the associated decreases in bone strength. Femurs (n= 85) for this study were collected through tissue sharing from rats used in other acute surgical procedures and were tested by using a 3-point bending flexural materials-testing machine. Our hypothesis was that, as a model for bone healing, 3 induced lesions of different sizes would show incremental and proportional decreases in femoral strength, with the intermediate-sized (1.5-mm) lesion demonstrating a decrease of 20% to 40%. A lesion of 1.5 mm yielded a decrease in strength of 17% for both the left and right femurs. The strength of left femurs carrying intermediate lesions was significantly less than that of control, uninjured femur bones. In addition to providing validation for our own future bone-healing project, these data are a useful baseline for other investigators studying bone healing in a rat femur model.Rodents, particularly rats, represent a reliable and affordable model for conducting basic research involving the skeleton.² Although biomechanical techniques for testing bone strength have been well documented, few studies define the theory, methods, and experimental procedures for evaluating the fracture toughness of bone (fracture resistance), especially whole-bone testing in small animals.¹⁰ This said, femurs are still the ideal rat and mouse bones to use to evaluate the fracture toughness properties in small-animal model studies.^4,10 Bending tests are useful to assess the mechanical properties of bones from rodents and other small animals.¹⁵ Even though this method of testing is referred to as a ‘bending test,’ the material (in this case, bone) is actually fractured to assess fracture toughness or breaking. For bending tests, long bones are loaded mainly in bending or compression during normal movement of the animals and are subject to both intrinsic and extrinsic large bending forces.^4,14 In rodents, locomotion results in alternating tension and compression on the cortex of weight-supporting bones during the gait cycle, with no limit on the magnitude or direction in which these forces can be exerted.⁸ This makes testing of bending, compression, torsion or any combination of methods potentially applicable. Therefore we chose to conduct 3-point bending testing on rat femurs. Bones were stressed to the point of fracture and the values required were recorded for computer-assisted analysis.In the testing of bone, the fundamental structural properties of greatest importance are stiffness, strength, and toughness.^8,10 Measured and calculated values of importance are peak force (ultimate breaking strength), fatigue resistance, stress, strain, break force, and energy to break. We chose to collect and compare peak force (measured data) as well as stress and break force (both calculated data). We made these choices because the most important biomechanical property from a clinical point of view is the peak force, which corresponds to the ability of a patient''s leg to resist high loading before a fracture or irreversible deformation occurs.Strength can be tested as tension, compression, bending, or shear.^8,10 Strength as a material parameter is defined as the ultimate stress at which failure occurs, but strength is defined structurally as the ultimate load (or force) when failure of the system occurs.⁸ In the current study, we tested the strength of rat femurs via 3-point bending. We hypothesized that the 1.5-mm lesion, which involved 39% of the bone circumference, would yield a 20% to 40% decrease in strength. In addition, the femurs with induced lesions showed a consistent decrease in strength, with larger lesions associated with lower peak force on both the right and left sides.     

Pullulan/dextran/nHA Macroporous Composite Beads for Bone Repair in a Femoral Condyle Defect in Rats

The repair of bone defects is of particular interest for orthopedic, oral, maxillofacial, and dental surgery. Bone loss requiring reconstruction is conventionally addressed through bone grafting. Depending on the size and the location of the defect, this method has limits and risks. Biomaterials can offer an alternative and have features supporting bone repair. Here, we propose to evaluate the cellular penetration and bone formation of new macroporous beads based on pullulan/dextran that has been supplemented with nanocrystalline hydroxyapatite in a rat model. Cross-linked beads of 300–500 µm diameters were used in a lateral femoral condyle defect and analyzed by magnetic resonance imaging, micro-computed tomography, and histology in comparison to the empty defects 15, 30, and 70 days after implantation. Inflammation was absent for both conditions. For empty defects, cellularisation and mineralization started from the periphery of the defect. For the defects containing beads, cellular structures filling out the spaces between the scaffolds with increasing interconnectivity and trabecular-like organization were observed over time. The analysis of calcified sections showed increased mineralization over time for both conditions, but was more pronounced for the samples containing beads. Bone Mineral Density and Bone Mineral Content were both significantly higher at day 70 for the beads in comparison to empty defects as well as compared with earlier time points. Analysis of newly formed tissue around the beads showed an increase of osteoid tissue, measured as percentage of the defect surface. This study suggests that the use of beads for the repair of small size defects in bone may be expanded on to meet the clinical need for a ready-to-use fill-up material that can favor bone formation and mineralization, as well as promote vessel ingrowth into the defect site.     

Repair of Chromosome Ends after Telomere Loss in Saccharomyces

Removal of a telomere from yeast chromosome VII in a strain having two copies of this chromosome often results in its loss. Here we show that there are three pathways that can stabilize this broken chromosome: homologous recombination, nonhomologous end joining, and de novo telomere addition. Both in a wild-type and a recombination deficient rad52 strain, most stabilization events were due to homologous recombination, whereas nonhomologous end joining was exceptionally rare. De novo telomere addition was relatively rare, stabilizing <0.1% of broken chromosomes. Telomere addition took place at a very limited number of sites on chromosome VII, most occurring close to a 35-base pair stretch of telomere-like DNA that is normally approximately 50 kb from the left telomere of chromosome VII. In the absence of the Pif1p DNA helicase, telomere addition events were much more frequent and were not concentrated near the 35-base pair tract of telomere-like DNA. We propose that internal tracts of telomere-like sequence recruit telomerase by binding its anchor site and that Pif1p inhibits telomerase by dissociating DNA primer-telomerase RNA interactions. These data also show that telomeric DNA is essential for the stable maintenance of linear chromosomes in yeast.