应用Micro CT测量下颌第二磨牙牙根尖到颊侧骨板的距离

目的运用Micro CT技术测量牙根尖到颊侧骨板的解剖距离。方法应用Micro CT(Skyscan 1072,Antwerpen,Belgium)及cutome计算机软件分析三维骨结构。结果下颌第二磨牙,近中根和远中根到颊侧骨板的距离平均为5.18mm和4.09mm。上颌骨的颊根中,上颌第二磨牙近中颊根和远中颊根到颊侧骨板的距离最大,分别是4.63mm和3.61mm。结论Micro CT是一种快速、准确、不损伤样本内部结构有效的评价方法。     

松质骨移植材料孔隙率的显微CT和组织切片测试方法比较

目的采用显微 CT法和组织切片法对松质骨移植材料的孔隙率进行对比研究,为骨组织工程支架材料的研制和开发提供理论依据.方法首先取新鲜尸体的股骨和新鲜猪股骨,进行去除多余组织、灭菌、低温冷冻保存等处理后,制备成松质骨移植材料,使用显微 CT分别扫描同种异体骨和动物源性猪骨移植材料获取显微 CT图像.然后对同种异体松质骨组织进行染色和切片等处理,制备成同种异体骨组织切片材料,显微镜下观察骨组织切片并获取其图像,各取10幅图像用于实验.设计matlab程序对所有图像进行灰度化、图像增强、二值化、移除干扰等处理,计算孔隙率的数值.结果显微CT和组织切片测试得到的同种异体松质骨孔隙率与动物源性猪松质骨孔隙率结果无显著性差异(P>0.05).结论显微 CT标本的制备较组织切片大为简化,可以无损地获取数据,并省去灰度化、图像增强、移除干扰等处理过程,比组织切片法测量松质骨孔隙率更加简便.     

Interpreting the three‐dimensional orientation of vascular canals and cross‐sectional geometry of cortical bone in birds and bats

Cortical bone porosity and specifically the orientation of vascular canals is an area of growing interest in biomedical research and comparative/paleontological anatomy. The potential to explain microstructural adaptation is of great interest. However, the determinants of the development of canal orientation remain unclear. Previous studies of birds have shown higher proportions of circumferential canals (called laminarity) in flight bones than in hindlimb bones, and interpreted this as a sign that circumferential canals are a feature for resistance to the torsional loading created by flight. We defined the laminarity index as the percentage of circumferential canal length out of the total canal length. In this study we examined the vascular canal network in the humerus and femur of a sample of 31 bird and 24 bat species using synchrotron micro‐computed tomography (micro‐CT) to look for a connection between canal orientation and functional loading. The use of micro‐CT provides a full three‐dimensional (3D) map of the vascular canal network and provides measurements of the 3D orientation of each canal in the whole cross‐section of the bone cortex. We measured several cross‐sectional geometric parameters and strength indices including principal and polar area moments of inertia, principal and polar section moduli, circularity, buckling ratio, and a weighted cortical thickness index. We found that bat cortices are relatively thicker and poorly vascularized, whereas those of birds are thinner and more highly vascularized, and that according to our cross‐sectional geometric parameters, bird bones have a greater resistance to torsional stress than the bats; in particular, the humerus in birds is more adapted to resist torsional stresses than the femur. Our results show that birds have a significantly (P = 0.031) higher laminarity index than bats, with birds having a mean laminarity index of 0.183 in the humerus and 0.232 in the femur, and bats having a mean laminarity index of 0.118 in the humerus and 0.119 in the femur. Counter to our expectation, the birds had a significantly higher laminarity index in the femur than in the humerus (P = 0.035). To evaluate whether this discrepancy was a consequence of methodology we conducted a comparison between our 3D method and an analogue to two‐dimensional (2D) histological measurements. This comparison revealed that 2D methods significantly underestimate (P < 0.001) the amount of longitudinal canals by an average of 20% and significantly overestimate (P < 0.001) the laminarity index by an average of 7.7%, systematically mis‐estimating indices of vascular canal orientations. In comparison with our 3D results, our approximated 2D measurement had the same results for comparisons between the birds and bats but found significant differences only in the longitudinal index between the humerus and the femur for both groups. The differences between our 3D and pseudo‐2D results indicate that differences between our findings and the literature may be partially based in methodology. Overall, our results do not support the hypothesis that the bones of flight are more laminar, suggesting a complex relation between functional loading and microstructural adaptation.     

基于CT图像的长管骨有限元材料属性研究及实验验证

目的探讨经酒精处理的新鲜人体长管骨个性化材料属性定义的方法,以及骨骼材料数目对有限元结果的影响。方法利用断层扫描CT图片,在Mimics中建立股骨干三维实体模型,然后导入Hypermesh中分割成皮质骨、松质骨以及骨髓;根据相关经验公式分别赋于皮质骨和松质骨的材料参数,设置5组材料数目的不同仿真组;在Abaqus中进行线弹性阶段的压缩实验仿真,并进行体外验证实验。结果端部位移在0～1 mm时,松质骨材料数目为1种,皮质骨材料数目大于10种的整体力-位移有限元仿真结果与实测数据平均相对误差在10%左右;骨干的测量点变形量的有限元结果与实测数据相对误差为14.6%。在小位移下0～0.5 mm时1,种皮质骨材料的整体力-位移的仿真结果与实测数据误差为2.83%。结论 (1)利用CT图片灰度值,可以精确定义骨骼各成份的材料属性;(2)皮质骨材料数目设定对有限元仿真结果影响较大,将皮质骨设定10种即可满足有限元分析需要;(3)小变形时,1种材料的皮质骨就能满足分析要求。     

核素骨显像评价组织工程骨修复骨缺损效果的价值

目的 应用放射性核素骨显像评价组织工程骨修复兔股骨髁骨缺损的效果。方法 取人白兔15只，抽取骨髓，行骨髓间充质干细胞分离、培养、骨向诱导。双侧股骨髁制作0．6×1．2cm的骨缺损，将诱导的成骨细胞复合珊瑚羟基磷灰石植入左侧，右侧单纯植入羟基磷灰石为对照组。术后4间、8周和12周分别行静态核素骨显像评价骨缺损的修复能力。结果表明术后4、8、12周实验组ROI计数（单位像素）均较对照组有显著性增高（P〈0．001）。实验组ROI计数随时间的延长呈明显的上升趋势，但术后8周始增长放缓；对照组ROI也有卜升趋势，但术后8周始增长加快，均在12周达到峰值。结论 骨髓间充质干细胞诱导后复合珊瑚羟基磷灰石可有效的修复股骨髁松质骨缺损。放射性核素骨显像在骨修复过程中具有动态评价血管化和骨生长的作用。     

Tissue differentiation and bone regeneration in an osteotomized mandible: a computational analysis of the latency period

Mandibular symphyseal distraction osteogenesis is a common clinical procedure to modify the geometrical shape of the mandible for correcting problems of dental overcrowding and arch shrinkage. In spite of consolidated clinical use, questions remain concerning the optimal latency period and the influence of mastication loading on osteogenesis within the callus prior to the first distraction of the mandible. This work utilized a mechano-regulation model to assess bone regeneration within the callus of an osteotomized mandible. A 3D model of the mandible was reconstructed from CT scan data and meshed using poroelastic finite elements (FE). The stimulus regulating tissue differentiation within the callus was hypothesized to be a function of the strain and fluid flow computed by the FE model. This model was then used to analyse tissue differentiation during a 15-day latency period, defined as the time between the day of the osteotomy and the day when the first distraction is given to the device. The following predictions are made: (1) the mastication forces generated during the latency period support osteogenesis in certain regions of the callus, and that during the latency period the percentage of progenitor cells differentiating into osteoblasts increases; (2) reducing the mastication load by 70% during the latency period increases the number of progenitor cells differentiating into osteoblasts; (3) the stiffness of new tissue increases at a slower rate on the side of bone callus next to the occlusion of the mandibular ramus which could cause asymmetries in the bone tissue formation with respect to the middle sagittal plane. Although the model predicts that the mastication loading generates such asymmetries, their effects on the spatial distribution of callus mechanical properties are insignificant for typical latency periods used clinically. It is also predicted that a latency period of longer than a week will increase the risk of premature bone union across the callus.     

Modelling the passive and nerve activated response of the rectus femoris muscle to a flexion loading: a finite element framework

A muscle modelling framework is presented which relates the mechanical response of the rectus femoris muscle (at the organ level) to tissue level properties, with the capability of linking to the cellular level as part of the IUPS Physiome Project. This paper will outline our current approach to muscle modelling incorporating micro-structural passive and active properties including fibre orientations and nerve innervation. The technique is based on finite deformation (using FE analysis) coupled to electrical nerve initiated muscle activation, and we present the influence of active tension through an eccentric contraction at specific flexion angles. Finally we discuss the future goals of incorporating cell mechanics and validating at the organ level to provide a complete diagnostic tool with the ability to relate mechanisms of failure across spatial scales.     

面神经颞骨内段在横断薄层和CT上的定位及临床意义

目的：为面神经及耳科病变的影像诊断和手术治疗提供解剖学基础。方法：15例成人头部标本，以眦耳线(CML)为基线，获得间隔为1．0mm，厚度为1．0mm的CT图像，扫描后的头部标本按原定位截取以耳颞区为中心的组织块并将其制成厚为1．0mm的连续横断薄层切片。标本切片与CT图像对照，对颞骨内面神经、听小骨、骨半规管、前庭、耳蜗等结构进行观测。结果：(1)面神经膝状神经节(GG)多位于外半规管层面。(2)匙突多与锤砧关节位于同一层面。(3)锥隆起多位于鼓岬层面。结论：面神经水平段起始部，GG，面神经迷路段三者在外半规管层面内呈倒“V”字型排列；面神经垂直段位于面神经隐窝深面，面神经隐窝、锥隆起、锥隐窝三者在鼓岬层面内从内向外呈“ω”字型排列。     

Breast cancer metastasis to bone: evaluation of bioluminescent imaging and microSPECT/CT for detecting bone metastasis in immunodeficient mice

This study sought to determine if weekly X-ray exposure affected breast cancer cell metastasis to bone and to also evaluate the use of bioluminescent imaging (BLI) and microSPECT for detection of metastatic bone lesions. Five week old nude mice were randomly assigned to the CT exposed (n = 7) and no CT exposure (n = 6) treatment groups. Mice received an intracardiac injection of MDA-MB-435 human breast cancer cells transduced with luciferase, or a sham injection (saline). The CT exposed group of mice received CT irradiation once a week for 5 weeks. All mice underwent weekly BLI and select mice received Tc-99m-MDP followed by microSPECT imaging after 5 weeks. Pathological evaluation and histomorphometry were used to assess the affect of CT X-rays on bone metastasis and to evaluate BLI. BLI results found no significant difference in metastasis between animals that received CT and those that did not (P > 0.05); however, histomorphometry of the knee joints revealed a significant increase (P = 0.029) in tumor area of the leg bones in mice that received CT exposure (60% ± 7%) compared to animals that did not receive CT scans (33% ± 8%). Compared to histological analysis, BLI of the leg and spine was determined to have excellent sensitivity (100%), good specificity (80–90%) and accuracy (90–96%), a positive predictive value of 81–93% and a 100% negative predictive value. Thus, multi-modality imaging techniques can be very useful for monitoring bone metastasis, however microCT X-rays should be used judiciously in order to limit irradiation that may stimulate increased metastasis to specific regions of the skeleton. MicroSPECT imaging did not detect metastatic lesions in the legs of these young nude mice.     

Simulated annealing implementation with shorter Markov chain length to reduce computational burden and its application to the analysis of pulmonary airway architecture

A new way to implement the Simulated Annealing (SA) algorithm was developed and tested that improves computation performance by using shorter Markov chain length (inner iterations) and repeating the entire SA process until the final function value meets the solution criterion. The new approach coupled with the adaptive neighborhood method was tested on the Rosenbrock function in 4 and 13 dimensions. This implementation significantly improved the computation speed without degrading solution quality. The proposed implementation was used to characterize pulmonary architecture from micro CT image data demonstrating the algorithm's effectiveness especially for problems with high computational demand and when the solution quality requirement can be pre-specified. Using this implementation, detailed statistics of the morphometry of conducting airways from 12 male Sprague Dawley rats were obtained for each lobe.     

Growth‐related structural,biochemical, and mechanical properties of the functional bone–cartilage unit

Articular cartilage and subchondral bone act together, forming a unit as a weight‐bearing loading‐transmitting surface. A close interaction between both structures has been implicated during joint cartilage degeneration, but their coupling during normal growth and development is insufficiently understood. The purpose of the present study was to examine growth‐related changes of cartilage mechanical properties and to relate these changes to alterations in cartilage biochemical composition and subchondral bone structure. Tibiae and femora of both hindlimbs from 7‐ and 13‐week‐old (each n = 12) female Sprague‐Dawley rats were harvested. Samples were processed for structural, biochemical and mechanical analyses. Immunohistochemical staining and protein expression analyses of collagen II, collagen IX, COMP and matrilin‐3, histomorphometry of cartilage thickness and COMP staining height were performed. Furthermore, mechanical testing of articular cartilage and micro‐CT analysis of subchondral bone was conducted. Growth decreased cartilage thickness, paralleled by a functional condensation of the underlying subchondral bone due to enchondral ossification. Cartilage mechanical properties seem to be rather influenced by growth‐related changes in the assembly of major ECM proteins such as collagen II, collagen IX and matrilin‐3 than by growth‐related alterations in its underlying subchondral bone structure. Importantly, the present study provides a first insight into the growth‐related structural, biochemical and mechanical interaction of articular cartilage and subchondral bone. Finally, these data contribute to the general knowledge about the cooperation between the articular cartilage and subchondral bone.     

Structure and mineralisation density of antler and pedicle bone in red deer (Cervus elaphus L.) exposed to different levels of environmental fluoride: a quantitative backscattered electron imaging study

The structure and relative degree of mineralisation of antler and pedicle bone of yearling red deer stags exposed either to low or high levels of environmental fluoride were determined by digital quantitative backscattered electron (BSE) imaging. Bone fluoride content (BFC) in antlers (845±86 mg F^?/kg ash, arithmetic mean±S.E.M. ) and pedicles (1448±154 mg F^?/kg ash) of deer from a highly fluoride polluted area in North Bohemia (Czech Republic) were significantly higher (P < 0.001) than those of controls from uncontaminated regions in West Germany (antlers: 206±41, pedicles: 322±52 mg F^?/kg ash). Mean (56.5±4.5%) and maximum (84.9±2.1%) mineralised bone area of the control antlers significantly (P < 0.05 and P < 0.001, respectively) exceeded the corresponding values for the N. Bohemian deer (43.3±1.3 and 73.3±1.9%, respectively), while the pedicles from the 2 groups did not differ significantly. In the pooled antler samples (n = 18), negative correlations existed between BFC and mean (r_s = ?0.62, P < 0.01) as well as maximum (r_s = ?0.69, P < 0.01) mineralised bone area. Morphological imaging revealed a decreased width and an increased porosity of the antler cortex in the N. Bohemian specimens. Mean (148.5±1.7) and maximum (154.2±1.7) BSE‐signal intensities (= grey levels; range between a monobrominated (grey level 0) and a monoiodinated (grey level 255) dimethacrylate resin standard) of the antlers from the controls were significantly higher than those of the N. Bohemian deer (140.7±2.1 and 145.7±2.2, respectively; P < 0.05 for both comparisons). In the pooled antler samples, negative correlations between BFC and mean (r_s = ?0.51, P < 0.05) as well as maximum (r_s = ?0.52, P < 0.05) BSE‐signal intensities were observed. No significant differences in mineralisation density parameters were found for the 2 pedicle samples, and BFC and mineralisation density of the pooled pedicles were uncorrelated. Morphological imaging revealed bone mottling (denoting increased remodelling activity) and frequent occurrence of apparently increased osteocyte lacunae in some of the pedicles from the N. Bohemian deer. It is concluded that the reduced amount of mineralised bone in, and the lower mineralisation density of, the N. Bohemian antlers resulted from a fluoride induced disturbance of bone mineralisation. The rapid growth of antlers leads both to a high mineral demand and a high rate of fluoride uptake during antlerogenesis. This, and the limited lifespan of antlers, which does not allow for a compensation of a delay in the onset or progression of the mineralisation process, renders antler bone particularly susceptible to fluoride. Antlers are therefore considered a useful model for studying fluoride effects on bone formation. Furthermore, analysis of cast antlers enables a noninvasive monitoring of environmental pollution by fluorides.     

Vascular tumors of bone: A study of 17 cases other than ordinary hemangioma,with an evaluation of the relationship of hemangioendothelioma of bone to epithelioid hemangioma,epithelioid hemangioendothelioma,and high-grade angiosarcoma

Cases filed as vascular tumor of bone other than ordinary hemangioma were reviewed. They were included in the study if there was adequate histologic material and clinical information, clear evidence of bone origin, and at least 5 years follow-up. The study group comprised 17 cases, of which 13 were categorized as hemangioendothelioma of bone, 1 as epithelioid hemangioendothelioma, and 3 as high-grade angiosarcoma. Hemangioendothelioma of bone had growth patterns varying from vasoformative to solid, but well-formed vessels were present in at least some area in all cases. The cells generally had a rounded, epithelioid character, regular nuclei, and relatively few mitotic figures; occasional features included spindle cells and scattered enlarged, hyperchromatic or pleomorphic nuclei. Lymphoplasmacytic and eosinophilic inflammatory infiltrate ranged from prominent to slight or absent, and myxoid or hyaline stroma was never more than focal. Epithelioid hemangioma could not be separated from hemangioendothelioma of bone. The single epithelioid hemangioendothelioma for the most part had cords of relatively uniform epithelioid cells in a prominent myxoid stroma but focally demonstrated an angiosarcoma-like appearance, with irregular vascular spaces and marked nuclear pleomorphism. The high-grade angiosarcomas exhibited predominantly irregular vasoformation combined with solid areas, diffuse nuclear hyperchromatism and pleomorphism, and, in 2 cases, numerous mitotic figures (the third case had only a small biopsy and a postradiation amputation specimen). Of the hemangioendotheliomas of bone, 7 were unicentric and 6 were regionally multicentric either concurrently or sequentially. Three patients had intraosseous local recurrence, 2 had discontinuous regional skin or soft tissue involvement (including the popliteal artery in 1), and 1 had a solitary lung metastasis, but none died of tumor. The patient with epithelioid hemangioendothelioma had multicentric tumors in widely separated bones and died with liver and lung metastases. Two of the high-grade angiosarcomas were unicentric, and the third was regionally multicentric, with a popliteal artery-soft tissue component as well. All 3 of these patients died with metastases in various sites.     

A new method to evaluate the elastic modulus of cortical bone by using a combined computed tomography and finite element approach

This study attempted to estimate the elastic modulus of cortical specimens directly from the computed tomography (CT) number (CT). Cubic specimens of fresh bovine femora were tested under compressive loading. The corresponding three-dimensional mesh models of these specimens were established with the aid of CT images. The elastic modulus of each element was determined using the following transfer formula: E=A×(CT)^B. The A and B were determined by matching the simulation results with the experimental force-displacement curves. An optimization approach was used to match the entire specimen sets between simulations and experiments. The results indicated that the elastic modulus of cortical bone can be effectively estimated using a power relationship (E=1.26×10⁻³×(CT)^1.93) directly from the CT number. This procedure eliminates the need to determine the bone density, and therefore reduces the computational time required to define mechanical properties in finite element methods.     

The response of bone, articular cartilage and tendon to exercise in the horse

Horses can gallop within hours of birth, and may begin training for athletic competition while still growing. This review cites studies on the effects of exercise on bone, tendon and articular cartilage, as detected by clinical and research imaging techniques, tissue biochemical analysis and microscopy of various kinds. For bone, alterations in bone mineral content, mineral density and the morphology of the mineralized tissue are the most common end-points. Apparent bone density increases slightly after athletic training in the cortex, but substantially in the major load paths of the epiphyses and cuboidal bones, despite the lower material density of the new bone, which is deposited subperiosteally and on internal surfaces without prior osteoclastic resorption. With training of greater intensity, adaptive change is supervened by patho-anatomical change in the form of microdamage and frank lesions. In tendon, collagen fibril diameter distribution changes significantly during growth, but not after early training. The exact amount and type of protracted training that does cause reduction in mass average diameter (an early sign of progressive microdamage) have not been defined. Training is associated with an increase in the cross-sectional area of some tendons, possibly owing to slightly greater water content of non-collagenous or newly synthesized matrix. Early training may be associated with greater thickness of hyaline but not calcified articular cartilage, at least in some sites. The age at which adaptation of cartilage to biomechanical influences can occur may thus extend beyond very early life. However, cartilage appears to be the most susceptible of the three tissues to pathological alteration. The effect of training exercise on the anatomical or patho-anatomical features of connective tissue structures is affected by the timing, type and amount of natural or imposed exercise during growth and development which precedes the training.     

Contribution of the spleen, lymph nodes and bone marrow to the antibody response in collagen-induced arthritis in the rat.

The relative contribution of different lymphoid tissues to the anti-CII antibody response was studied in rats with arthritis produced as a result of immunizing them with collagen type II (CII). Antibody production was measured by maintaining lymphoid cells in short-term culture in collagen-coated microculture wells: the antibody they secreted was determined directly by a modified ELISA. Systemic sensitization to CII was established within a week of immunization, and a stronger response in the local draining lymph nodes relative to the spleen was associated with the development of clinical disease. From experiments involving splenectomy and adoptive cell transfer, the spleen was ascribed a suppressive role in controlling both arthritis and total antibody production. The bone marrow was found to be an important site of antibody production and the greater production of antibody by cells from tibial marrow in limbs with arthritis, compared with healthy limbs, argues for a local immune response to degrading joint antigens that may have systemic suppressive or protective properties. It is concluded that local immunity reflects the state of disease and that the antibodies produced by different lymphoid tissues may be made in response to different stimuli, and that the antibodies in turn may have different pathological effects.