Is the callus shape an optimal response to a mechanobiological stimulus?

After bone trauma, the natural response to restore bone function is the formation of a callus around the fracture. Although several bone healing models have been developed, none have effectively perceived early callus formation and shape as the result of an optimal response to a mechanobiological stimulus.In this paper, we investigate which stimulus regulates early callus formation. An optimal design problem is formulated, and several objective functions are defined, each using a different mechanobiological stimulus. The following stimuli were analysed: the interfragmentary strain, the second invariant of the deviatoric strain tensor and a generic inflammatory factor. Different regions for callus formation were also evaluated, such as the gap region, the periosteum and the periosteum border. Each stimulus was computed using the finite element method, and the callus shape was optimised using the steepest descent method.The results demonstrated that the inflammatory factor approach, the interfragmentary strain and the second invariant of the deviatoric strain tensor over the inner gap provided the best results when compared with histological callus shapes. Therefore, this work suggests that callus growth can be an optimal mechanobiological response to either local mechanical instability and/or local inflammatory reaction.     

骨形态发生蛋白4与血管钙化的相关性

骨形态发生蛋白4(BMP-4)是转化生长因子β(TGF-β)超家族成员之一,属于多功能生长因子,在胚胎发育、血管生成、细胞增殖、分化、骨骼形成、异位成骨、骨折修复等方面具有重要作用。血管钙化(VC)是一个与骨发育相似的可调控的复杂的生物学过程,其中心环节是血管平滑肌细胞(VSMC)向成骨样细胞转化。近年的研究发现,BMP-4可能参与血管钙化的发生和发展,但具体机制尚未清楚,文章就其相关关系的研究进展作一综述。     

Osteodistraction of mandibles with a small bone defect at the planned osteotomy site: A histological pilot study in dogs

AimTo develop a treatment plan for cases in which a bone defect is located on the osteotomy line of mandibular osteodistraction (DO).Subjects and methodsBilateral DO was performed in 17 Mongrel dogs. Prior to surgery, the 34 hemi-mandibles were randomly allocated to three groups: C (n = 10; a standard DO was performed), D − G (n = 12; a bone defect was created on the DO osteotomy line), and D + G (n = 12; the bone defect on the osteotomy line was grafted). After one week of latency, 8 days of distraction, and 4 weeks of consolidation the animals were sacrificed, and the newly formed bone were examined.ResultsIn group C, two zones of immature trabecular bone originating from host bone margins were separated by a central fibrous zone. In group D + G uniform new bone formation of the entire distraction gap was observed. In group D − G the distraction gap was mainly filled with fibrous tissue. The values for the newly formed bone volume and trabecular thickness were not significantly different between groups D + G and C, but were higher than values in group D − G (p < 0.05).ConclusionWhen a mandibular defect is located at the site of distraction osteotomy, DO can be performed simultaneous with bone grafting of the defect.     

Exercise in neuromuscular disease

In this review, we present an overview of the role of exercise in neuromuscular disease (NMD). We demonstrate that despite the different pathologies in NMDs, exercise is beneficial, whether aerobic/endurance or strength/resistive training, and we explore whether this benefit has a similar mechanism to that of healthy subjects. We discuss further areas for study, incorporating imaginative and novel approaches to training and its assessment in NMD. We conclude by suggesting ways to improve future trials by avoiding previous methodological flaws and drawbacks in this field. Muscle Nerve, 2013     

Preparation,characterization and bioactivities of nano anhydrous calcium phosphate added gelatin–chitosan scaffolds for bone tissue engineering

Abstract

Gelatin, chitosan and nano calcium phosphate based composite scaffold with tailored architectures and properties has great potential for bone regeneration. Herein, we aimed to improve the physico chemical, mechanical and osteogenic properties of 3D porous scaffold by incorporation of dihydrogen calcium phosphate anhydrous (DCPA) nanoparticles into biopolymer matrix with variation in composition in the prepared scaffolds. Scaffolds were prepared from the slurry containing gelatin, chitosan and synthesized nano DCPA particle using lyophilization technique. DCPA nano particles were synthesized using calcium carbonate and phosphoric acid in water–ethanol medium. XRD pattern showed phase pure DCPA in synthesized nanopowder. Scaffolds were prepared by addition of DCPA nanoparticles to the extent of 5–10?wt% of total polymer into gelatin–chitosan solution with solid loading varying between 2.5 and 2.75?wt%. The prepared scaffold showed interconnected porosity with pore size varying between 110 and 200 micrometer. With addition of DCPA nanoparticles, average pore size of the prepared scaffolds decreased. With increase in nano ceramic phase content from 5?wt% to 10?wt% of total polymer, the compressive strength of the scaffold increased. Scaffold containing 10?wt% DCPA showed the highest average compressive strength of 2.2?MPa. Higher cellular activities were observed in DCPA containing scaffolds as compared to pure gelatin chitosan scaffold suggesting the fact that nano DCPA addition into the scaffold promoted better osteoblast adhesion and proliferation as evident from MTT assay and scanning electron microscopic (SEM) investigation of osteoblast cultured scaffolds. A higher degree of lamellopodia and filopodia extensions and better spreading behavior of osteoblasts were observed in FESEM micrographs of MG 63 cultured DCPA containing scaffold. The results demonstrated that both mechanical strength and osteogenic properties of gelatin–chitosan scaffold could be improved by addition of anhydrous dihydrogen calcium phosphate nanoparticles into it.     

Effects of laparoscopic Roux-en-Y gastric bypass on bone mineral density and markers of bone turnover

BackgroundDespite multiple beneficial effects of weight loss after laparoscopic Roux-en-Y gastric bypass (LRYGB), the influence on bone mineral density (BMD) remains largely unknown. Our objective was to evaluate the changes in BMD and serum/urine bone markers after LRYGB.MethodsThirty-four women undergoing LRYGB were prospectively enrolled and underwent bone densitometry and serum/urine analysis preoperatively and 1 year postoperative. Changes≥.025 g/cm² in hip, femoral neck, and spine BMD and decreases>2% in total BMD were considered significant. Statistical analysis included paired t tests and McNemar’s test.ResultsMean age was 44.6 years. Body mass index at the preoperative and 1-year postoperative intervals were 46.7 and 29.6 kg/m², respectively. Mean hip, femoral neck, and spine (L1–L4) BMD was 1.191 versus 1.087 g/cm² (P< .001), 1.105 versus 1.032 g/cm² (P< .001), and 1.323 versus 1.277 g/cm² (P< .001) at the preoperative and 1 year postoperative intervals, respectively. Mean total BMD decreased from 1.328 preoperatively to 1.251 g/cm² at 1 year postoperative (P<.001). The decreases in BMD were 5.8%, 6.5%, 3.5%, and 8.8% for hip, femoral neck, spine (L1–L4) and total BMD from preoperative to 1 year postoperative. The proportion of patients with low vitamin D levels decreased from 55% preoperatively to 21% at 1 year postoperative (P = .004). Elevated osteocalcin and bone alkaline phosphatase was observed in 4% and 63% (P<.001), and 14% and 41% (P = .011) of patients preoperatively and at 1 year postoperative, respectively.ConclusionBMD and bone markers changed significantly after LRYGB. Current recommendations for supplementation in post-LRYGB women may need to be reevaluated.     

bFGF基因转染MSC目的基因检测

目的：探讨碱性成纤维细胞生长因子（bFGF）基因外源性转染到MSC（骨髓间充质细胞）后，bFGF基因的表达情况。方法选取SD大鼠，获取骨髓间充质细胞，分为对照组、阴性对照组（转染外源性GFP）和实验组（外源性bFGF转染MSC），经过体外培养后，应用RT-PCR和ELISE法检测各组MSC的bFGF基因阳性表达情况。结果 RT-PCR法显示实验组bFGF基因表达量（0.73±0.15）高于对照组和阴性对照组（P＜0.05）。ELISA法显示bFGF基因表达主要集中在胞浆，实验组bFGF基因表达量[上清为（5.38±0.45）ng/L，胞浆为（8.27±0.82）ng/L]高于其他两组（P＜0.05）。结论采用病毒介导基因转染技术能够将外源性bFGF转染至MSC，并能够成功实现bFGF基因表达。     

Effects of the environment on bone mass: A human taphonomic study

An experiment was designed using human ribs placed in different environments to document how moisture and temperature affect the bone mass according to the postmortem interval. The bones were defleshed, weighed and partially buried, with some ribs being left unburied as controls. The ribs were weighed daily, and the mass loss was monitored over a period of 90 days. The results showed that significant differences in bone mass loss exist between environments, where the bone mass loss was significantly faster in an environment with low moisture content. This mass loss is thought to be primarily associated with the desiccation of the body and then for a greater part, with the atmospheric moisture content. However, the loss of bone mass can also be explained by early alterations in the organo-mineral matrix which were highlighted by Raman spectroscopy method.