大豆异黄酮对骨质疏松模型大鼠骨量及微观结构的影响

为研究大豆异黄酮（SI）对骨质疏松模型大鼠骨量及微观结构的影响,将46只雌性SD大鼠双侧摘除卵巢,术后一周按血清总胆固醇水平随机分为5组,分别给予雌激素,低、中、高剂量SI干预并设正常对照组,实验周期为12周,灌胃给药,每周称质量一次,分别在去卵巢、给药4、8周处死时抽取尾静脉血,实验结束后分别测定血清碱性磷酸酶（AKP）活性及骨密度等指标。结果表明,高剂量SI干预对维持大鼠骨密度的作用与雌激素相似,去卵巢后干预SI可提高碱性磷酸酶（AKP）活性并能缓解因去卵巢造成的骨丢失,全视野下骨形态学以雌激素组、高剂量SI干预组与正常组结构最为接近。提示大豆异黄酮对骨质疏松模型大鼠的骨量及微观结构存在一定影响,中、高剂量干预可使骨质疏松模型大鼠血清AKP酶活性增加、逆转因去势造成的骨密度下降,考虑到植物雌激素与哺乳动物的雌激素受体（ER）结合能力低下,采用SI在临床开展干预的剂量与远期效果尚待进一步论证。     

Dose in Skeleton and Bone Marrow following Thorotrast Injection into Blood

The calculation of the dose rate and cumulative dose in the morrow-free skeleton and bone marrow of thorotrast patients presupposes the knowledge of both the translocation of thorium daughters to the skeleton, and the portion of ²³²Th that is localized in colloidal form in the bone marrow. Whereas in bon marrow ²²⁸Th is in equilibrium with ²³²Th up to only 20%, in marrow-free skeleton ²²⁸Th is present in excess to ²³²Th (average activity ratio 1·75), considering the measured activity ratios between ²³²Th and its daughters as well as the distribution of the colloid and the unclides of the thorium decay chain within the organism the dose rate and cumulative dose in bone marrow and marrow-free bone were calculated as function of the time of thorotrast burden and the amount of injected material.     

Nanoindentation of wet and dry compact bone: Influence of environment and indenter tip geometry on the indentation modulus

The indentation-derived elastic modulus, E, of bovine compact bone was obtained by nanoindentation. The indentation modulus of the dry condition (i.e. under atmospheric conditions) is 40% higher than when measured wet (i.e. immersed in buffer solution). Although this difference is independent of orientation, there is a 20% difference in the indentation modulus within the same tested environment between longitudinal and transversal directions. In addition, the estimated indentation modulus of the same samples when tested wet in buffer solution after deep freezing (?15°C) was not affected. The discrepancy between wet and dry results was attributed to the non-mineralized phase contribution and rationalized by a simple mechanical model [I. Jäger and P. Fratzl, Biophys. J. 79 (2000) p.1737]. Anisotropy effects could be explained in terms of deformation mechanisms with orientation. The effect of frozen storage temperatures may be clarified considering the biomechanics of the helicoidal arrangement of lamellar bone. Viscoelastic effects were also considered and incorporated into analysis of the force–displacement data.     

Fabrication of Nanofiber Scaffolds With Gradations in Fiber Organization and Their Potential Applications

A new and simple method for fabrication of nanofiber scaffolds with gradations in fiber organization is reported. The nanofiber organization, achieved by deposition of random fibers on the uniaxially aligned nanofiber mat in a gradient manner, directed morphological changes of applied adipose‐derived stem cells. These morphological changes and resultant biochemical changes can help mimic the structural orientation of complex biomechanical structures like the collagen fiber structure at the tendon‐to‐bone insertion site. In addition, chemical gradients can be established through nanoencapsulation in this novel scaffold allowing for enhanced biomedical applications.

     

Oxygen Plasma Technology-Assisted Preparation of Three-Dimensional Reduced Graphene Oxide/Polypyrrole/Strontium Composite Scaffold for Repair of Bone Defects Caused by Osteoporosis

Repairs of bone defects caused by osteoporosis have always relied on bone tissue engineering. However, the preparation of composite tissue engineering scaffolds with a three-dimensional (3D) macroporous structure poses huge challenges in achieving osteoconduction and osteoinduction for repairing bone defects caused by osteoporosis. In the current study, a three-dimensional macroporous (150–300 μm) reduced graphene oxide/polypyrrole composite scaffold modified by strontium (Sr) (3D rGO/PPY/Sr) was successfully prepared using the oxygen plasma technology-assisted method, which is simple, safe, and inexpensive. The findings of the MTT assay and AO/EB fluorescence double staining showed that 3D rGO/PPY/Sr has a good biocompatibility and effectively promoted MC3T3-E1 cell proliferation. Furthermore, the ALP assay and alizarin red staining showed that 3D rGO/PPY/Sr increased the expression levels of ALP activity and the formation of calcified nodules. The desirable biocompatibility, osteoconduction, and osteoinduction abilities, assure that the 3D macroporous rGO/PPY/Sr composite scaffold offers promising potential for use in the repair of bone defects caused by osteoporosis in bone tissue engineering.     

Study of the circumstance influence on the elemental distribution in ancient animal bone using μ-XRF

Elemental analysis of archaeological bone plays an important role in the study of the dietary habits of ancient animals. The elemental characteristic of diagenetic skeletons depends on the surrounding circumstance. The study of environmental influence on the elemental concentration of ancient bone is significant. In this paper, the diagenetic influence on archaeological skeletons is analyzed by microbeam X-ray fluorescence （p.-XRF）. The results show that the enamel is an excellent barrier to the diagenesis and the element Sr in bone isn＇t susceptible to contamination from the buried environment.     

Semi-empirical bone model for determination of trabecular structure properties from backscattered ultrasound

A novel semi-empirical scattering model of trabecular bone facilitating its characterization and allowing optimization of the interrogating pulse-echo transducer performance was developed. The model accounts for spatial density distribution of the trabeculae and includes measurement conditions such as pressure–time waveform of the probing ultrasound wave, the emitted field structure, and the transfer function and limited bandwidth of the acoustic source operating in pulse-echo mode. These measurement conditions are of importance as they modify the scattered echoes, which in turn are linked to the micro-architecture of the bone. The bone was modeled by a random distribution of long and thin cylindrical scatterers having randomly varying diameters and mechanical properties, and oriented perpendicularly to the ultrasound beam axis. To mimic clinically encountered conditions the relevant empirical data obtained at 1 MHz were input to the model. The data included pulse-echo source pressure field distribution in the focal zone and the above mentioned transfer function. With these data the model allowed frequency dependent backscattering coefficient of the simulated bone structure and its statistical properties to be determined. The results obtained indicated that the computer simulation is of particular relevance in studying scattering properties of the cancellous bone and holds promise as a tool to determine the relationship between the physical dimensions and shape of the scatterers and for monitoring of osteoporosis. The results of simulations also indicated that the new bone model proposed is well suited to mimic clinically relevant conditions. In contrast to the existing bone models, which usually assume scatterers to be randomly distributed as infinitely long identical cylinders with a cross-section much smaller than the probing ultrasound wave, the new model includes two populations of scatterers having different physical dimensions and also allows the mechanical properties of the scatterers to be varied.     

Co-Treatment of Purified Annatto Oil (Bixa orellana L.) and Its Granules (Chronic®) Improves the Blood Lipid Profile and Bone Protective Effects of Testosterone in the Orchiectomy-Induced Osteoporosis in Wistar Rats

This study aimed to evaluate and compare the effects of co-treatment with purified annatto oil (PAO) or its granules (GRA, Chronic^®) with that of testosterone on the orchiectomy-induced osteoporosis in Wistar rats. After surgery, rats were treated from day 7 until day 45 with testosterone only (TES, 7 mg/kg, IM) or TES + PAO or GRA (200 mg/kg, p.o.). The following parameters were evaluated: food/water intake, weight, HDL, LDL, glucose, triglycerides (TG), total cholesterol (TC), alkaline phosphatase levels, blood phosphorus and calcium contents, femur weight, structure (through scanning electron microscopy), and calcium content (through atomic absorption spectrophotometry). Our results show that orchiectomy could significantly change the blood lipid profile and decrease bone integrity parameters. Testosterone reposition alone could improve some endpoints, including LDL, TC, bone weight, and bone calcium concentration. However, other parameters were not significantly improved. Co-treatment with PAO or GRA improved the blood lipid profile and bone integrity more significantly and improved some endpoints not affected by testosterone reposition alone (such as TG levels and trabeculae sizes). The results suggest that co-treatment with annatto products improved the blood lipid profile and the anti-osteoporosis effects of testosterone. Overall, GRA had better results than PAO.     

Fabrication and Evaluation of Alginate/Bacterial Cellulose Nanocrystals–Chitosan–Gelatin Composite Scaffolds

It is common knowledge that pure alginate hydrogel is more likely to have weak mechanical strength, a lack of cell recognition sites, extensive swelling and uncontrolled degradation, and thus be unable to satisfy the demands of the ideal scaffold. To address these problems, we attempted to fabricate alginate/bacterial cellulose nanocrystals-chitosan-gelatin (Alg/BCNs-CS-GT) composite scaffolds using the combined method involving the incorporation of BCNs in the alginate matrix, internal gelation through the hydroxyapatite-d-glucono-δ-lactone (HAP-GDL) complex, and layer-by-layer (LBL) electrostatic assembly of polyelectrolytes. Meanwhile, the effect of various contents of BCNs on the scaffold morphology, porosity, mechanical properties, and swelling and degradation behavior was investigated. The experimental results showed that the fabricated Alg/BCNs-CS-GT composite scaffolds exhibited regular 3D morphologies and well-developed pore structures. With the increase in BCNs content, the pore size of Alg/BCNs-CS-GT composite scaffolds was gradually reduced from 200 μm to 70 μm. Furthermore, BCNs were fully embedded in the alginate matrix through the intermolecular hydrogen bond with alginate. Moreover, the addition of BCNs could effectively control the swelling and biodegradation of the Alg/BCNs-CS-GT composite scaffolds. Furthermore, the in vitro cytotoxicity studies indicated that the porous fiber network of BCNs could fully mimic the extracellular matrix structure, which promoted the adhesion and spreading of MG63 cells and MC3T3-E1 cells on the Alg/BCNs-CS-GT composite scaffolds. In addition, these cells could grow in the 3D-porous structure of composite scaffolds, which exhibited good proliferative viability. Based on the effect of BCNs on the cytocompatibility of composite scaffolds, the optimum BCNs content for the Alg/BCNs-CS-GT composite scaffolds was 0.2% (w/v). On the basis of good merits, such as regular 3D morphology, well-developed pore structure, controlled swelling and biodegradation behavior, and good cytocompatibility, the Alg/BCNs-CS-GT composite scaffolds may exhibit great potential as the ideal scaffold in the bone tissue engineering field.     

切应力对牛骨蠕变变形的影响研究

骨尤其是湿骨,在恒定载荷作用下会发生蠕变变形。为了确定切应力是否影响骨的蠕变变形,采用对骨薄板试样分别施加集中载荷和均布载荷的方式,测量试样挠度实时的变化曲线。结果显示,在载荷恒定时,骨试样的挠度随时间不断增加,体现了典型的蠕变特性。集中荷载下骨的蠕变变形远大于均布荷载下骨的蠕变变形,湿骨的蠕变位移比干骨高近7倍。分析认为,对试样粘弹性性质的影响不仅有正应力的作用,也有切应力的作用;切应力产生的蠕变变形约为正应力所产生蠕变变形的0.85倍。