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Sample records for modeling bone structure

  1. Animal Models for Evaluation of Bone Implants and Devices: Comparative Bone Structure and Common Model Uses.

    Science.gov (United States)

    Wancket, L M

    2015-09-01

    Bone implants and devices are a rapidly growing field within biomedical research, and implants have the potential to significantly improve human and animal health. Animal models play a key role in initial product development and are important components of nonclinical data included in applications for regulatory approval. Pathologists are increasingly being asked to evaluate these models at the initial developmental and nonclinical biocompatibility testing stages, and it is important to understand the relative merits and deficiencies of various species when evaluating a new material or device. This article summarizes characteristics of the most commonly used species in studies of bone implant materials, including detailed information about the relevance of a particular model to human bone physiology and pathology. Species reviewed include mice, rats, rabbits, guinea pigs, dogs, sheep, goats, and nonhuman primates. Ultimately, a comprehensive understanding of the benefits and limitations of different model species will aid in rigorously evaluating a novel bone implant material or device. © The Author(s) 2015.

  2. Animal models of maternal nutrition and altered offspring bone structureBone development across the lifecourse

    OpenAIRE

    SA Lanham; C Bertram; C Cooper; ROC Oreffo

    2011-01-01

    It is widely accepted that the likelihood of offspring developing heart disease, stroke, or diabetes in later life, is influenced by the their in utero environment and maternal nutrition. There is increasing epidemiological evidence that osteoporosis in the offspring may also be influenced by the mother’s nutrition during pregnancy. This review provides evidence from a range of animal models that supports the epidemiological data; suggesting that lifelong bone development and growth in offspr...

  3. Gender-dependence of bone structure and properties in adult osteogenesis imperfecta murine model.

    Science.gov (United States)

    Yao, Xiaomei; Carleton, Stephanie M; Kettle, Arin D; Melander, Jennifer; Phillips, Charlotte L; Wang, Yong

    2013-06-01

    Osteogenesis imperfecta (OI) is a dominant skeletal disorder characterized by bone fragility and deformities. Though the oim mouse model has been the most widely studied of the OI models, it has only recently been suggested to exhibit gender-dependent differences in bone mineralization. To characterize the impact of gender on the morphometry/ultra-structure, mechanical properties, and biochemical composition of oim bone on the congenic C57BL/J6 background, 4-month-old oim/oim, +/oim, and wild-type (wt) female and male tibiae were evaluated using micro-computed tomography, three-point bending, and Raman spectroscopy. Dramatic gender differences were evident in both cortical and trabecular bone morphological and geometric parameters. Male mice had inherently more bone and increased moment of inertia than genotype-matched female counterparts with corresponding increases in bone biomechanical strength. The primary influence of gender was structure/geometry in bone growth and mechanical properties, whereas the mineral/matrix composition and hydroxyproline content of bone were influenced primarily by the oim collagen mutation. This study provides evidence of the importance of gender in the evaluation and interpretation of potential therapeutic strategies when using mouse models of OI.

  4. Accurate Fabrication of Hydroxyapatite Bone Models with Porous Scaffold Structures by Using Stereolithography

    Energy Technology Data Exchange (ETDEWEB)

    Maeda, Chiaki; Tasaki, Satoko; Kirihara, Soshu, E-mail: c-maeda@jwri.osaka-u.ac.jp [Joining and Welding Research Institute, Osaka University, 11-1 Mihogaoka, Ibaraki City, Osaka 567-0047 (Japan)

    2011-05-15

    Computer graphic models of bioscaffolds with four-coordinate lattice structures of solid rods in artificial bones were designed by using a computer aided design. The scaffold models composed of acryl resin with hydroxyapatite particles at 45vol. % were fabricated by using stereolithography of a computer aided manufacturing. After dewaxing and sintering heat treatment processes, the ceramics scaffold models with four-coordinate lattices and fine hydroxyapatite microstructures were obtained successfully. By using a computer aided analysis, it was found that bio-fluids could flow extensively inside the sintered scaffolds. This result shows that the lattice structures will realize appropriate bio-fluid circulations and promote regenerations of new bones.

  5. Accurate Fabrication of Hydroxyapatite Bone Models with Porous Scaffold Structures by Using Stereolithography

    International Nuclear Information System (INIS)

    Maeda, Chiaki; Tasaki, Satoko; Kirihara, Soshu

    2011-01-01

    Computer graphic models of bioscaffolds with four-coordinate lattice structures of solid rods in artificial bones were designed by using a computer aided design. The scaffold models composed of acryl resin with hydroxyapatite particles at 45vol. % were fabricated by using stereolithography of a computer aided manufacturing. After dewaxing and sintering heat treatment processes, the ceramics scaffold models with four-coordinate lattices and fine hydroxyapatite microstructures were obtained successfully. By using a computer aided analysis, it was found that bio-fluids could flow extensively inside the sintered scaffolds. This result shows that the lattice structures will realize appropriate bio-fluid circulations and promote regenerations of new bones.

  6. Structure model index does not measure rods and plates in trabecular bone

    Directory of Open Access Journals (Sweden)

    Phil L Salmon

    2015-10-01

    Full Text Available Structure model index (SMI is widely used to measure rods and plates in trabecular bone. It exploits the change in surface curvature that occurs as a structure varies from spherical (SMI = 4, to cylindrical (SMI = 3 to planar (SMI = 0. The most important assumption underlying SMI is that the entire bone surface is convex and that the curvature differential is positive at all points on the surface. The intricate connections within the trabecular continuum suggest that a high proportion of the surface could be concave, violating the assumption of convexity and producing regions of negative differential. We implemented SMI in the BoneJ plugin and included the ability to measure the amounts of surface that increased or decreased in area after surface mesh dilation, and the ability to visualize concave and convex regions. We measured SMI and its positive (SMI+ and negative (SMI- components, bone volume fraction (BV/TV, the fraction of the surface that is concave (CF, and mean ellipsoid factor (EF in trabecular bone using 38 X-ray microtomography (XMT images from a rat ovariectomy model of sex steroid rescue of bone loss, and 169 XMT images from a broad selection of 87 species' femora (mammals, birds, and a crocodile. We simulated bone resorption by eroding an image of elephant trabeculae and recording SMI and BV/TV at each erosion step. Up to 70%, and rarely less than 20%, of the trabecular surface is concave (CF 0.155 – 0.700. SMI is unavoidably influenced by aberrations from SMI-, which is strongly correlated with BV/TV and CF. The plate-to-rod transition in bone loss is an erroneous observation resulting from SMI's close and artefactual relationship with BV/TV. SMI cannot discern between the distinctive trabecular geometries typical of mammalian and avian bone, whereas EF clearly detects birds' more plate-like trabeculae. EF is free from confounding relationships with BV/TV and CF. SMI results reported in the literature should be treated with

  7. Computationally-optimized bone mechanical modeling from high-resolution structural images.

    Directory of Open Access Journals (Sweden)

    Jeremy F Magland

    Full Text Available Image-based mechanical modeling of the complex micro-structure of human bone has shown promise as a non-invasive method for characterizing bone strength and fracture risk in vivo. In particular, elastic moduli obtained from image-derived micro-finite element (μFE simulations have been shown to correlate well with results obtained by mechanical testing of cadaveric bone. However, most existing large-scale finite-element simulation programs require significant computing resources, which hamper their use in common laboratory and clinical environments. In this work, we theoretically derive and computationally evaluate the resources needed to perform such simulations (in terms of computer memory and computation time, which are dependent on the number of finite elements in the image-derived bone model. A detailed description of our approach is provided, which is specifically optimized for μFE modeling of the complex three-dimensional architecture of trabecular bone. Our implementation includes domain decomposition for parallel computing, a novel stopping criterion, and a system for speeding up convergence by pre-iterating on coarser grids. The performance of the system is demonstrated on a dual quad-core Xeon 3.16 GHz CPUs equipped with 40 GB of RAM. Models of distal tibia derived from 3D in-vivo MR images in a patient comprising 200,000 elements required less than 30 seconds to converge (and 40 MB RAM. To illustrate the system's potential for large-scale μFE simulations, axial stiffness was estimated from high-resolution micro-CT images of a voxel array of 90 million elements comprising the human proximal femur in seven hours CPU time. In conclusion, the system described should enable image-based finite-element bone simulations in practical computation times on high-end desktop computers with applications to laboratory studies and clinical imaging.

  8. A novel use of 3D printing model demonstrates the effects of deteriorated trabecular bone structure on bone stiffness and strength.

    Science.gov (United States)

    Barak, Meir Max; Black, Margaret Arielle

    2018-02-01

    Trabecular bone structure is crucial to normal mechanical behavior of bones. Studies have shown that osteoporosis negatively affects trabecular bone structure, mainly by reducing bone volume fraction (BV/TV) and thus increasing fracture risk. One major limitation in assessing and quantifying the effect of this structural deterioration is that no two trabecular structures are identical. Thus, when we compare a group of healthy bones against a different group of bones that experienced resorption (i.e. decreased BV/TV) we only discover an "average" mechanical effect. It is impossible to quantify the mechanical effect of individual structural deterioration for each sample, simply because we never have the same sample in both states (intact and deteriorated structure). 3D printing is a new technology that can assist in overcoming this issue. Here we report a preliminary study that compares a healthy 3D printed trabecular bone model with the same model after bone resorption was simulated. Since the deteriorated structural bone model is derived from the healthy one, it is possible to directly estimate (percentage wise) the decrease of tissue stiffness and strength as a result of bone resorption for this specific structure. Our results demonstrate that a relatively small decrease in BV/TV (about 8%) leads to a dramatic decrease in structural strength (24%) and structural stiffness (17%), (P strength decreased from an average of 9.14 ± 2.85MPa to 6.97 ± 2.44MPa, while structural stiffness decreased from an average of 282.5 ± 63.4N/mm to 233.8 ± 51.2N/mm. This study demonstrates that 3D printing is a novel and valuable tool for quantifying the effect of structural deterioration on the mechanical properties of trabecular bone. In the future, this approach may help us attain better personal fracture risk assessments by CT scanning, 3D printing and mechanically testing individual bone replicas from patients suffering excessive bone resorption. Copyright © 2017 Elsevier Ltd

  9. Mammalian hibernation as a model of disuse osteoporosis: the effects of physical inactivity on bone metabolism, structure, and strength.

    Science.gov (United States)

    McGee-Lawrence, Meghan E; Carey, Hannah V; Donahue, Seth W

    2008-12-01

    Reduced skeletal loading typically leads to bone loss because bone formation and bone resorption become unbalanced. Hibernation is a natural model of musculoskeletal disuse because hibernating animals greatly reduce weight-bearing activity, and therefore, they would be expected to lose bone. Some evidence suggests that small mammals like ground squirrels, bats, and hamsters do lose bone during hibernation, but the mechanism of bone loss is unclear. In contrast, hibernating bears maintain balanced bone remodeling and preserve bone structure and strength. Differences in the skeletal responses of bears and smaller mammals to hibernation may be due to differences in their hibernation patterns; smaller mammals may excrete calcium liberated from bone during periodic arousals throughout hibernation, leading to progressive bone loss over time, whereas bears may have evolved more sophisticated physiological processes to recycle calcium, prevent hypercalcemia, and maintain bone integrity. Investigating the roles of neural and hormonal control of bear bone metabolism could give valuable insight into translating the mechanisms that prevent disuse-induced bone loss in bears into novel therapies for treating osteoporosis.

  10. The influence of severe prolonged exercise restriction on the mechanical and structural properties of bone in an avian model.

    Science.gov (United States)

    Shipov, Anna; Sharir, Amnon; Zelzer, Elazar; Milgram, Joshua; Monsonego-Ornan, Efrat; Shahar, Ron

    2010-02-01

    Many studies have described the effects of exercise restriction on the mammalian skeleton. In particular, human and animal models have shown that reduction in weight bearing leads to generalised bone loss and deterioration of its mechanical properties. The aim of this study was to assess the effect of prolonged exercise restriction coupled with heavy calcium demands on the micro-structural, compositional and mechanical properties of the avian skeleton. The tibiae and humeri of 2-year-old laying hens housed in conventional caging (CC) and free-range (FR) housing systems were compared by mechanical testing and micro-computed tomography (microCT) scanning. Analyses of cortical, cancellous and medullary bone were performed. Mechanical testing revealed that the tibiae and humeri of birds from the FR group had superior mechanical properties relative to those of the CC group, and microCT scanning indicated larger cortical and lower medullary regions in FR group bones. Cancellous bone analysis revealed higher trabecular thickness and a higher bone volume fraction in the FR group, but no difference in mineral density. The biomechanical superiority of bones from the FR group was primarily due to structural rather than compositional differences, and this was reflected in both the cortical and cancellous components of the bones. The study demonstrated that prolonged exercise restriction in laying hens resulted in major structural and mechanical effects on the bird skeleton. Copyright (c) 2008 Elsevier Ltd. All rights reserved.

  11. A second gradient continuum model accounting for some effects of micro-structure on reconstructed bone remodelling

    Science.gov (United States)

    Madeo, Angela; George, D.; Lekszycki, T.; Nierenberger, Mathieu; Rémond, Yves

    2012-08-01

    We propose a second gradient, two-solids, continuum mixture model with variable masses to describe the effect of micro-structure on mechanically-driven remodelling of bones grafted with bio-resorbable materials. A one-dimensional numerical simulation is addressed showing the potentialities of the proposed generalized continuum model. In particular, we show that the used second gradient model allows for the description of some micro-structure-related size effects which are known to be important in hierarchically heterogeneous materials like reconstructed bones. Moreover, the influence of the introduced second gradient parameters on the final percentages of replacement of artificial bio-material with natural bone tissue is presented and discussed.

  12. Mammalian hibernation as a model of disuse osteoporosis: the effects of physical inactivity on bone metabolism, structure, and strength

    OpenAIRE

    McGee-Lawrence, Meghan E.; Carey, Hannah V.; Donahue, Seth W.

    2008-01-01

    Reduced skeletal loading typically leads to bone loss because bone formation and bone resorption become unbalanced. Hibernation is a natural model of musculoskeletal disuse because hibernating animals greatly reduce weight-bearing activity, and therefore, they would be expected to lose bone. Some evidence suggests that small mammals like ground squirrels, bats, and hamsters do lose bone during hibernation, but the mechanism of bone loss is unclear. In contrast, hibernating bears maintain bala...

  13. Photogrammetry in 3d Modelling of Human Bone Structures from Radiographs

    Science.gov (United States)

    Hosseinian, S.; Arefi, H.

    2017-05-01

    Photogrammetry can have great impact on the success of medical processes for diagnosis, treatment and surgeries. Precise 3D models which can be achieved by photogrammetry improve considerably the results of orthopedic surgeries and processes. Usual 3D imaging techniques, computed tomography (CT) and magnetic resonance imaging (MRI), have some limitations such as being used only in non-weight-bearing positions, costs and high radiation dose(for CT) and limitations of MRI for patients with ferromagnetic implants or objects in their bodies. 3D reconstruction of bony structures from biplanar X-ray images is a reliable and accepted alternative for achieving accurate 3D information with low dose radiation in weight-bearing positions. The information can be obtained from multi-view radiographs by using photogrammetry. The primary step for 3D reconstruction of human bone structure from medical X-ray images is calibration which is done by applying principles of photogrammetry. After the calibration step, 3D reconstruction can be done using efficient methods with different levels of automation. Because of the different nature of X-ray images from optical images, there are distinct challenges in medical applications for calibration step of stereoradiography. In this paper, after demonstrating the general steps and principles of 3D reconstruction from X-ray images, a comparison will be done on calibration methods for 3D reconstruction from radiographs and they are assessed from photogrammetry point of view by considering various metrics such as their camera models, calibration objects, accuracy, availability, patient-friendly and cost.

  14. 3D hierarchical geometric modeling and multiscale FE analysis as a base for individualized medical diagnosis of bone structure.

    Science.gov (United States)

    Podshivalov, L; Fischer, A; Bar-Yoseph, P Z

    2011-04-01

    This paper describes a new alternative for individualized mechanical analysis of bone trabecular structure. This new method closes the gap between the classic homogenization approach that is applied to macro-scale models and the modern micro-finite element method that is applied directly to micro-scale high-resolution models. The method is based on multiresolution geometrical modeling that generates intermediate structural levels. A new method for estimating multiscale material properties has also been developed to facilitate reliable and efficient mechanical analysis. What makes this method unique is that it enables direct and interactive analysis of the model at every intermediate level. Such flexibility is of principal importance in the analysis of trabecular porous structure. The method enables physicians to zoom-in dynamically and focus on the volume of interest (VOI), thus paving the way for a large class of investigations into the mechanical behavior of bone structure. This is one of the very few methods in the field of computational bio-mechanics that applies mechanical analysis adaptively on large-scale high resolution models. The proposed computational multiscale FE method can serve as an infrastructure for a future comprehensive computerized system for diagnosis of bone structures. The aim of such a system is to assist physicians in diagnosis, prognosis, drug treatment simulation and monitoring. Such a system can provide a better understanding of the disease, and hence benefit patients by providing better and more individualized treatment and high quality healthcare. In this paper, we demonstrate the feasibility of our method on a high-resolution model of vertebra L3. Copyright © 2010 Elsevier Inc. All rights reserved.

  15. Understanding the Structure of Bones

    Science.gov (United States)

    ... structure of bone is very similar to reinforced concrete that is used to make a building or ... a defective blueprint is produced that tells the cell to produce deformed collagen, resulting in bad collagen ...

  16. Multiscale Modeling of Bone

    Science.gov (United States)

    2014-12-01

    risk ?,” Equine Veterinary J., vol. 42, no. 2, pp. 174– 180, Mar. 2010. [127] J. J. Sciote and T. J. Morris, “Skeletal muscle function and fibre...shear properties of fibrils, fibers, and lamellar layers. A layered composite model assessed cortical and trabecular bone while a simple finite element...to be assessed . It was found that the distribution of hydroxyapatite within the tropocollagen matrix at the fibril level influences the macroscale

  17. 3D Modelling and monitoring of denervated muscle under Functional Electrical Stimulation treatment and associated bone structural changes

    Directory of Open Access Journals (Sweden)

    Paolo Gargiulo

    2011-03-01

    Full Text Available A novel clinical rehabilitation method for patients who have permanent and non recoverable muscle denervation in the legs was developed in the frame of the European Project RISE. The technique is based on FES and the project results shows, in these severely disabled patients, restoration of muscle tissue and function. This study propose novel methods based on image processing technique and medical modelling to monitor growth in denervated muscle treated with FES. Geometrical and structural changes in muscle and bone are studied and modelled. Secondary effects on the bone mineral density produced by the stimulation treatment and due the elicited muscle contraction are also investigated. The restoration process in DDM is an important object of discussion since there isn’t yet a complete understanding of the mechanisms regulating growth in denervated muscle. This study approaches the problem from a macroscopic point of view, developing 3-dimensional models of the whole stimulated muscles and following changes in volume, geometry and density very accurately. The method is based on the acquisition of high resolution Spiral CT scans from patients who have long-term flaccid paraplegia and the use of special image processing tools allowing tissue discriminations and muscle segmentation. Three patients were measured at different points of time during 4 years of electrical stimulation treatment. In this study is quantitatively demonstrated the influences of FES treatment on the different quadriceps bellies. The rectus femoris muscle is positioned in the middle of the quadriceps and responds (in general better to stimulation. In a patient with abundant adipose tissue surrounding the quadriceps, rectus femoris almost doubled the volume during the FES treatment while in the other bellies the changes measured were minimal. The analysis of the density shows clearly a restoration of the muscular structure in the growing muscle. The remarkable increase of

  18. Ossicular bone modeling in acute otitis media

    DEFF Research Database (Denmark)

    Salomonsen, Rasmus Lysholdt; Hermansson, Ann; Cayé-Thomasen, Per

    2010-01-01

    A number of middle ear diseases are associated with pathologic bone modeling, either formative or resorptive. As such, the pathogenesis of a sclerotic mastoid has been controversial for decades. Experimental studies on acute middle ear infection have shown progressive osteoneogenesis in the bone ...... structures surrounding the middle ear cavity, and a few studies have reported acute changes of the ossicular chain. However, detailed qualitative and quantitative information on ossicular bone modeling dynamics has not been accounted for and is thus the purpose of this study....

  19. Measures of Complexity to quantify Bone Structure

    Science.gov (United States)

    Saparin, Peter; Gowin, Wolfgang; Kurths, Jürgen; Felsenberg, Dieter

    1998-03-01

    We propose a technique to assess structure of the bone in its spatial distribution by describing and quantifying the structural architecture as a whole. The concept of measures of complexity based on symbolic dynamics is applied to computed tomography (CT) - images obtained from human lumbar vertebra. CT-images have been transformed into images consisting of 5 different symbols, whereby both statical and dynamical coding are included. Different aspects of the bone structure are quantified by several measures which have been introduced: index of global ensemble of elements composing the bone; complexity, homogeneity and dynamics within the bone architecture; complexity and inhomogeneity of the trabecular net. This leads to new insides to the understanding of bone's internal structure. The results give the first experimental and quantitative evidence of the theoretical prediction that complexity of bone structure declines rapidly with the increased disintegration of bone structures leading to the loss of bone mass and specify experimentally that bone structure is exponentially related to its density. Especially, osteoporotic vertebrae are less complex organized than normal ones. In addition, this method is significantly sensitive to changes in bone structure and provides improvements of diagnostic of pathological structural loss.

  20. Permeability study of cancellous bone and its idealised structures.

    Science.gov (United States)

    Syahrom, Ardiyansyah; Abdul Kadir, Mohammed Rafiq; Harun, Muhamad Nor; Öchsner, Andreas

    2015-01-01

    Artificial bone is a suitable alternative to autografts and allografts, however their use is still limited. Though there were numerous reports on their structural properties, permeability studies of artificial bones were comparably scarce. This study focused on the development of idealised, structured models of artificial cancellous bone and compared their permeability values with bone surface area and porosity. Cancellous bones from fresh bovine femur were extracted and cleaned following an established protocol. The samples were scanned using micro-computed tomography (μCT) and three-dimensional models of the cancellous bones were reconstructed for morphology study. Seven idealised and structured cancellous bone models were then developed and fabricated via rapid prototyping technique. A test-rig was developed and permeability tests were performed on the artificial and real cancellous bones. The results showed a linear correlation between the permeability and the porosity as well as the bone surface area. The plate-like idealised structure showed a similar value of permeability to the real cancellous bones. Copyright © 2014 IPEM. Published by Elsevier Ltd. All rights reserved.

  1. Erythropoietin modulates the structure of bone morphogenetic protein 2-engineered cranial bone.

    Science.gov (United States)

    Sun, Hongli; Jung, Younghun; Shiozawa, Yusuke; Taichman, Russell S; Krebsbach, Paul H

    2012-10-01

    The ideally engineered bone should have similar structural and functional properties to the native tissue. Although structural integrity is critical for functional bone regeneration, we know less about modulating the structural properties of the engineered bone elicited by bone morphogenetic protein (BMP) than efficacy and safety. Erythropoietin (Epo), a primary erythropoietic hormone, has been used to augment blood transfusion in orthopedic surgery. However, the effects of Epo on bone regeneration are not well known. Here, we determined the role of Epo in BMP2-induced bone regeneration using a cranial defect model. Epo administration improved the quality of BMP2-induced bone and more closely resembled natural cranial bone with a higher bone volume (BV) fraction and lower marrow fraction when compared with BMP2 treatment alone. Epo increased red blood cells (RBCs) in peripheral blood and also increased hematopoietic and mesenchymal stem cell (MSC) populations in bone marrow. Consistent with our previous work, Epo increased osteoclastogenesis both in vitro and in vivo. Results from a metatarsal organ culture assay suggested that Epo-promoted osteoclastogenesis contributed to angiogenesis because angiogenesis was blunted when osteoclastogenesis was blocked by alendronate (ALN) or osteoprotegerin (OPG). Earlier calcification of BMP2-induced temporary chondroid tissue was observed in the Epo+BMP group compared to BMP2 alone. We conclude that Epo significantly enhanced the outcomes of BMP2-induced cranial bone regeneration in part through its actions on osteoclastogenesis and angiogenesis.

  2. A digital model of trabecular bone.

    Science.gov (United States)

    Engelke, K; Song, S M; Glüer, C C; Genant, H K

    1996-04-01

    A 3D microCT dataset of bovine bone was used to create a digital 3D model simulating trabecular bone. The model serves a dual purpose: It allows for standard quantitative histomorphometric analysis and it approximates the reality e.g. of high resolution CT in vivo datasets of trabecular bone. Thus the model can potentially be used as a reference to develop 2D and 3D structural analysis algorithms applicable in vivo while it simultaneously allows verification of the results of these algorithms by standard histomorphometry. The model can be used as a standard to evaluate the impact of image processing techniques and of restrictions of imaging systems on the quantitative analysis of structural parameters describing a trabecular network. The model can be used for a comparison of 2D and 3D structural analysis methods and for an analysis of decreasing spatial resolution. The effects of segmentation and filtration can be studied separately and grayscale analysis is possible. As examples standard 2D histomorphometry and the analysis of topological parameters like node number and trabecular network length were applied to the model. The influence of spatial resolution was investigated by decreasing the spatial resolution of the digital model. The bone surface area determined by 3D surface triangulation was only 4% smaller than the surface area determined from the traditional 2D bone histomorphometric parameter bone surface/tissue volume (BS/TV) when 2D results were averaged over all slices of the 3D volume. However, BS/TV showed large (10%) variations among slices within the volume. Both histomorphometric and topological parameters were heavily influenced by spatial resolution and image segmentation. Our initial experience with the digital model indicates a need to investigate bone microstructure based on volume data or to average the 2D results of many slices.

  3. Three-Dimensional Virtual Bone Bank System Workflow for Structural Bone Allograft Selection: A Technical Report

    Directory of Open Access Journals (Sweden)

    Lucas Eduardo Ritacco

    2013-01-01

    Full Text Available Structural bone allograft has been used in bone defect reconstruction during the last fifty years with acceptable results. However, allograft selection methods were based on 2-dimensional templates using X-rays. Thanks to preoperative planning platforms, three-dimensional (3D CT-derived bone models were used to define size and shape comparison between host and donor. The purpose of this study was to describe the workflow of this virtual technique in order to explain how to choose the best allograft using a virtual bone bank system. We measured all bones in a 3D virtual environment determining the best match. The use of a virtual bone bank system has allowed optimizing the allograft selection in a bone bank, providing more information to the surgeons before surgery. In conclusion, 3D preoperative planning in a virtual environment for allograft selection is an important and helpful tool in order to achieve a good match between host and donor.

  4. Mechanical characterization of structurally porous biomaterials built via additive manufacturing: experiments, predictive models, and design maps for load-bearing bone replacement implants.

    Science.gov (United States)

    Melancon, D; Bagheri, Z S; Johnston, R B; Liu, L; Tanzer, M; Pasini, D

    2017-11-01

    Porous biomaterials can be additively manufactured with micro-architecture tailored to satisfy the stringent mechano-biological requirements imposed by bone replacement implants. In a previous investigation, we introduced structurally porous biomaterials, featuring strength five times stronger than commercially available porous materials, and confirmed their bone ingrowth capability in an in vivo canine model. While encouraging, the manufactured biomaterials showed geometric mismatches between their internal porous architecture and that of its as-designed counterpart, as well as discrepancies between predicted and tested mechanical properties, issues not fully elucidated. In this work, we propose a systematic approach integrating computed tomography, mechanical testing, and statistical analysis of geometric imperfections to generate statistical based numerical models of high-strength additively manufactured porous biomaterials. The method is used to develop morphology and mechanical maps that illustrate the role played by pore size, porosity, strut thickness, and topology on the relations governing their elastic modulus and compressive yield strength. Overall, there are mismatches between the mechanical properties of ideal-geometry models and as-manufactured porous biomaterials with average errors of 49% and 41% respectively for compressive elastic modulus and yield strength. The proposed methodology gives more accurate predictions for the compressive stiffness and the compressive strength properties with a reduction of the average error to 11% and 7.6%. The implications of the results and the methodology here introduced are discussed in the relevant biomechanical and clinical context, with insight that highlights promises and limitations of additively manufactured porous biomaterials for load-bearing bone replacement implants. In this work, we perform mechanical characterization of load-bearing porous biomaterials for bone replacement over their entire design

  5. Trabecular bone structure analysis of the spine using clinical MDCT: can it predict vertebral bone strength?

    Science.gov (United States)

    Baum, Thomas; Gräbeldinger, Martin; Räth, Christoph; Garcia, Eduardo Grande; Burgkart, Rainer; Patsch, Janina M; Rummeny, Ernst J; Link, Thomas M; Bauer, Jan S

    2014-01-01

    Recent technical improvements have made it possible to determine trabecular bone structure parameters of the spine using clinical multi-detector computed tomography (MDCT). Therefore, the purpose of this study was to analyze trabecular bone structure parameters obtained from clinical MDCT in relation to high resolution peripheral quantitative computed tomography (HR-pQCT) as a standard of reference and to investigate whether clinical MDCT can predict vertebral bone strength. Fourteen functional spinal segment units between T7 and L3 were harvested from 14 formalin-fixed human cadavers (11 women and 3 men; age 84 ± 10 years). All functional spinal segment units were examined using HR-pQCT (isotropic voxel size of 41 μm(3)) and a clinical whole-body MDCT (interpolated voxel size of 146 × 146 × 300 μm(3)). Trabecular bone structure analyses (histomorphometric and texture measures) were performed in the HR-pQCT as well as MDCT images. Vertebral failure load (FL) of the functional spinal segment units was determined in an uniaxial biomechanical test. The HR-pQCT and MDCT derived trabecular bone structure parameters showed correlations ranging from r = 0.60 to r = 0.90 (p 0.05). In this cadaver model, the spatial resolution of clinically available whole-body MDCT scanners was suitable for trabecular bone structure analysis of the spine and to predict vertebral bone strength.

  6. Mathematical model for bone mineralization

    Directory of Open Access Journals (Sweden)

    Svetlana V Komarova

    2015-08-01

    Full Text Available Defective bone mineralization has serious clinical manifestations, including deformities and fractures, but the regulation of this extracellular process is not fully understood. We have developed a mathematical model consisting of ordinary differential equations that describe collagen maturation, production and degradation of inhibitors, and mineral nucleation and growth. We examined the roles of individual processes in generating normal and abnormal mineralization patterns characterized using two outcome measures: mineralization lag time and degree of mineralization. Model parameters describing the formation of hydroxyapatite mineral on the nucleating centers most potently affected the degree of mineralization, while the parameters describing inhibitor homeostasis most effectively changed the mineralization lag time. Of interest, a parameter describing the rate of matrix maturation emerged as being capable of counter-intuitively increasing both the mineralization lag time and the degree of mineralization. We validated the accuracy of model predictions using known diseases of bone mineralization such as osteogenesis imperfecta and X-linked hypophosphatemia. The model successfully describes the highly non-linear mineralization dynamics, which includes an initial lag phase when osteoid is present but no mineralization is evident, then fast primary mineralization, followed by secondary mineralization characterized by a continuous slow increase in bone mineral content. The developed model can potentially predict the function for a mutated protein based on the histology of pathologic bone samples from mineralization disorders of unknown etiology.

  7. Microtomographic imaging in the process of bone modeling and simulation

    Science.gov (United States)

    Mueller, Ralph

    1999-09-01

    Micro-computed tomography ((mu) CT) is an emerging technique to nondestructively image and quantify trabecular bone in three dimensions. Where the early implementations of (mu) CT focused more on technical aspects of the systems and required equipment not normally available to the general public, a more recent development emphasized practical aspects of micro- tomographic imaging. That system is based on a compact fan- beam type of tomograph, also referred to as desktop (mu) CT. Desk-top (mu) CT has been used extensively for the investigation of osteoporosis related health problems gaining new insight into the organization of trabecular bone and the influence of osteoporotic bone loss on bone architecture and the competence of bone. Osteoporosis is a condition characterized by excessive bone loss and deterioration in bone architecture. The reduced quality of bone increases the risk of fracture. Current imaging technologies do not allow accurate in vivo measurements of bone structure over several decades or the investigation of the local remodeling stimuli at the tissue level. Therefore, computer simulations and new experimental modeling procedures are necessary for determining the long-term effects of age, menopause, and osteoporosis on bone. Microstructural bone models allow us to study not only the effects of osteoporosis on the skeleton but also to assess and monitor the effectiveness of new treatment regimens. The basis for such approaches are realistic models of bone and a sound understanding of the underlying biological and mechanical processes in bone physiology. In this article, strategies for new approaches to bone modeling and simulation in the study and treatment of osteoporosis and age-related bone loss are presented. The focus is on the bioengineering and imaging aspects of osteoporosis research. With the introduction of desk-top (mu) CT, a new generation of imaging instruments has entered the arena allowing easy and relatively inexpensive access to

  8. Mathematical model for bone mineralization

    OpenAIRE

    Komarova, Svetlana V.; Safranek, Lee; Gopalakrishnan, Jay; Ou, Miao-jung Yvonne; McKee, Marc D.; Murshed, Monzur; Rauch, Frank; Zuhr, Erica

    2015-01-01

    Defective bone mineralization has serious clinical manifestations, including deformities and fractures, but the regulation of this extracellular process is not fully understood. We have developed a mathematical model consisting of ordinary differential equations that describe collagen maturation, production and degradation of inhibitors, and mineral nucleation and growth. We examined the roles of individual processes in generating normal and abnormal mineralization patterns characterized usin...

  9. Correlating implant stability to bone structure.

    Science.gov (United States)

    Rozé, Julie; Babu, Stéphanie; Saffarzadeh, Afchine; Gayet-Delacroix, Marie; Hoornaert, Alain; Layrolle, Pierre

    2009-10-01

    The aim of this study was to demonstrate a possible correlation between bone microarchitecture and primary implant stability. Twenty-two implants (Ankylos((R)) and Straumann((R))) were inserted into the maxillae and mandibles of human cadavers. Bone structure was determined by computed tomography in three specimens (male, age 53; female, 67; female, 80). A strict clinical protocol was used for implantation. Primary implant stability was measured by resonance frequency analysis (Osstell Mentor). The bone structure was analyzed by micro-computed tomography (CT). Bone histomorphometrical parameters were calculated and correlated to primary implant stability. Implant stability quotients (ISQ) ranged from 50 to 70% depending on the specimens and sites. Histomorphometry indicated differences in the bone microstructures of the specimens. However, ISQ values were not related to trabecular bone histomorphometrical parameters. The sole correlation was found between ISQ values and cortical bone thickness. This study confirms the relevance for primary stability of cortical thickness around implants. The thickness of cortical bone can be assessed using a standard clinical CT.

  10. An adaptation model for trabecular bone at different mechanical levels

    Directory of Open Access Journals (Sweden)

    Lv Linwei

    2010-07-01

    Full Text Available Abstract Background Bone has the ability to adapt to mechanical usage or other biophysical stimuli in terms of its mass and architecture, indicating that a certain mechanism exists for monitoring mechanical usage and controlling the bone's adaptation behaviors. There are four zones describing different bone adaptation behaviors: the disuse, adaptation, overload, and pathologic overload zones. In different zones, the changes of bone mass, as calculated by the difference between the amount of bone formed and what is resorbed, should be different. Methods An adaptation model for the trabecular bone at different mechanical levels was presented in this study based on a number of experimental observations and numerical algorithms in the literature. In the proposed model, the amount of bone formation and the probability of bone remodeling activation were proposed in accordance with the mechanical levels. Seven numerical simulation cases under different mechanical conditions were analyzed as examples by incorporating the adaptation model presented in this paper with the finite element method. Results The proposed bone adaptation model describes the well-known bone adaptation behaviors in different zones. The bone mass and architecture of the bone tissue within the adaptation zone almost remained unchanged. Although the probability of osteoclastic activation is enhanced in the overload zone, the potential of osteoblasts to form bones compensate for the osteoclastic resorption, eventually strengthening the bones. In the disuse zone, the disuse-mode remodeling removes bone tissue in disuse zone. Conclusions The study seeks to provide better understanding of the relationships between bone morphology and the mechanical, as well as biological environments. Furthermore, this paper provides a computational model and methodology for the numerical simulation of changes of bone structural morphology that are caused by changes of mechanical and biological

  11. STRUCTURAL MODELLING

    Directory of Open Access Journals (Sweden)

    Tea Ya. Danelyan

    2014-01-01

    Full Text Available The article states the general principles of structural modeling in aspect of the theory of systems and gives the interrelation with other types of modeling to adjust them to the main directions of modeling. Mathematical methods of structural modeling, in particular method of expert evaluations are considered.

  12. Development of Bone Remodeling Model for Spaceflight Bone Physiology Analysis

    Science.gov (United States)

    Pennline, James A.; Werner, Christopher R.; Lewandowski, Beth; Thompson, Bill; Sibonga, Jean; Mulugeta, Lealem

    2015-01-01

    Current spaceflight exercise countermeasures do not eliminate bone loss. Astronauts lose bone mass at a rate of 1-2% a month (Lang et al. 2004, Buckey 2006, LeBlanc et al. 2007). This may lead to early onset osteoporosis and place the astronauts at greater risk of fracture later in their lives. NASA seeks to improve understanding of the mechanisms of bone remodeling and demineralization in 1g in order to appropriately quantify long term risks to astronauts and improve countermeasures. NASA's Digital Astronaut Project (DAP) is working with NASA's bone discipline to develop a validated computational model to augment research efforts aimed at achieving this goal.

  13. Chronic Alcohol Abuse Leads to Low Bone Mass with No General Loss of Bone Structure or Bone Mechanical Strength

    DEFF Research Database (Denmark)

    Ulhøi, Maiken Parm; Meldgaard, Karoline; Steiniche, Torben

    2017-01-01

    Chronic alcohol abuse (CAA) has deleterious effects on skeletal health. This study examined the impact of CAA on bone with regard to bone density, structure, and strength. Bone specimens from 42 individuals with CAA and 42 individuals without alcohol abuse were obtained at autopsy. Dual-energy X...... wall thickness of trabecular osteons compared to individuals without alcohol abuse. No significant difference was found for bone strength and structure. Conclusion: CAA leads to low bone mass due to a decrease in bone formation but with no destruction of bone architecture nor a decrease in bone...

  14. Permeability studies of artificial and natural cancellous bone structures.

    Science.gov (United States)

    Syahrom, Ardiyansyah; Abdul Kadir, Mohammed Rafiq; Abdullah, Jaafar; Öchsner, Andreas

    2013-06-01

    In the development of artificial cancellous bones, two major factors need to be considered: the integrity of the overall structure and its permeability. Whilst there have been many studies analysing the mechanical properties of artificial and natural cancellous bones, permeability studies, especially those using numerical simulation, are scarce. In this study, idealised cancellous bones were simulated from the morphological indices of natural cancellous bone. Three different orientations were also simulated to compare the anisotropic nature of the structure. Computational fluid dynamics methods were used to analyse fluid flow through the cancellous structures. A constant mass flow rate was used to determine the intrinsic permeability of the virtual specimens. The results showed similar permeability of the prismatic plate-and-rod model to the natural cancellous bone. The tetrakaidecahedral rod model had the highest permeability under simulated blood flow conditions, but the plate counterpart had the lowest. Analyses on the anisotropy of the virtual specimens showed the highest permeability for the horizontal orientation. Linear relationships were found between permeability and the two physical properties, porosity and bone surface area. Copyright © 2012 IPEM. Published by Elsevier Ltd. All rights reserved.

  15. Bone and marrow dose modeling

    International Nuclear Information System (INIS)

    Stabin, Michael G.

    2004-01-01

    Nuclear medicine therapy is being used increasingly in the treatment of cancer (thyroid, leukemia/lymphoma with RIT, primary and secondary bone malignancies, and neuroblastomas). In all cases it is marrow toxicity that limits the amount of treatment that can be administered safely. Marrow dose calculations are more difficult than for many major organs because of the intricate association of bone and soft tissue elements. In RIT, there appears to be no consensus on how to calculate that dose accurately, or of individual patients ability to tolerate planned therapy. Available dose models are designed after an idealized average, healthy individual. Patient-specific methods are applied in evaluation of biokinetic data, and need to be developed for treatment of the physical data (dose conversion factors) as well: age, prior patient therapy, disease status. Contributors to marrow dose: electrons and photons

  16. Three Dimensional Cancellous Bone Structure in Hypoparathyroidism

    Science.gov (United States)

    Rubin, Mishaela R.; Dempster, David W.; Kohler, Thomas; Stauber, Martin; Zhou, Hua; Shane, Elizabeth; Nickolas, Thomas; Stein, Emily; Sliney, James; Silverberg, Shonni J.; Bilezikian, John P.; Müller, Ralph

    2009-01-01

    By conventional 2-dimensional histomorphometric analysis, we have shown that cancellous bone architecture is markedly altered in hypoparathyroidism. We have now extended these observations to a 3-dimensional analysis using microcomputed tomography. Percutaneous iliac crest bone biopsies were analyzed by high-resolution microcomputed tomography from the following 25 subjects with hypoparathyroidism: 5 postmenopausal women, 13 premenopausal women and 7 men. Thirteen living premenopausal healthy controls and 12 cadaver subjects without bone disease served as matched controls. Hypoparathyroid subjects had significantly greater bone surface density (BS/TV: 5.74 ± 4.7 vs. 3.73 ± 1.01 mm2/mm3 [mean ± SD]; p=0.04), trabecular thickness (Tb.Th: 0.25 ± 0.19 vs. 0.17 ± 0.04 mm; p=0.04), trabecular number (Tb.N: 2.99 ± 3.4 vs. 1.62 ± 0.39 mm−1; p=0.05) and connectivity density (Conn.D: 16.63 ± 18.7 vs. 8.39 ± 5.8 mm3; p=0.04) in comparison to matched controls. When an additional 8 hypoparathyorid (total n= 33) and 24 cadaver (total cadaver n= 36) subjects were added to the groups for an unmatched analysis, hypoparathyroid subjects had significantly greater cancellous bone volume (BV/TV: 26.98 ± 10 vs. 15.39 ± 4%; phypoparathyroid subjects, as assessed by microcomputed tomography, were highly correlated with those assessed by conventional histomorphometry. We conclude that cancellous bone in hypoparathyroidism is abnormal, suggesting that parathyroid hormone is required to maintain normal trabecular structure. The effect of these structural changes on bone strength remains to be determined. PMID:19782782

  17. Chronic Alcohol Abuse Leads to Low Bone Mass with No General Loss of Bone Structure or Bone Mechanical Strength.

    Science.gov (United States)

    Ulhøi, Maiken Parm; Meldgaard, Karoline; Steiniche, Torben; Odgaard, Anders; Vesterby, Annie

    2017-01-01

    Chronic alcohol abuse (CAA) has deleterious effects on skeletal health. This study examined the impact of CAA on bone with regard to bone density, structure, and strength. Bone specimens from 42 individuals with CAA and 42 individuals without alcohol abuse were obtained at autopsy. Dual-energy X-ray absorptiometry (DEXA), compression testing, ashing, and bone histomorphometry were performed. Individuals with CAA had significantly lower bone mineral density (BMD) in the femoral neck and significantly lower bone volume demonstrated by thinner trabeculae, decreased extent of osteoid surfaces, and lower mean wall thickness of trabecular osteons compared to individuals without alcohol abuse. No significant difference was found for bone strength and structure. CAA leads to low bone mass due to a decrease in bone formation but with no destruction of bone architecture nor a decrease in bone strength. It is questionable whether this per se increases fracture risk. © 2016 American Academy of Forensic Sciences.

  18. Biology of Bone Tissue: Structure, Function, and Factors That Influence Bone Cells.

    Science.gov (United States)

    Florencio-Silva, Rinaldo; Sasso, Gisela Rodrigues da Silva; Sasso-Cerri, Estela; Simões, Manuel Jesus; Cerri, Paulo Sérgio

    2015-01-01

    Bone tissue is continuously remodeled through the concerted actions of bone cells, which include bone resorption by osteoclasts and bone formation by osteoblasts, whereas osteocytes act as mechanosensors and orchestrators of the bone remodeling process. This process is under the control of local (e.g., growth factors and cytokines) and systemic (e.g., calcitonin and estrogens) factors that all together contribute for bone homeostasis. An imbalance between bone resorption and formation can result in bone diseases including osteoporosis. Recently, it has been recognized that, during bone remodeling, there are an intricate communication among bone cells. For instance, the coupling from bone resorption to bone formation is achieved by interaction between osteoclasts and osteoblasts. Moreover, osteocytes produce factors that influence osteoblast and osteoclast activities, whereas osteocyte apoptosis is followed by osteoclastic bone resorption. The increasing knowledge about the structure and functions of bone cells contributed to a better understanding of bone biology. It has been suggested that there is a complex communication between bone cells and other organs, indicating the dynamic nature of bone tissue. In this review, we discuss the current data about the structure and functions of bone cells and the factors that influence bone remodeling.

  19. Quantification of spatial structure of human proximal tibial bone biopsies using 3D measures of complexity

    DEFF Research Database (Denmark)

    Saparin, Peter I.; Thomsen, Jesper Skovhus; Prohaska, Steffen

    2005-01-01

    Changes in trabecular bone composition during development of osteoporosis are used as a model for bone loss in microgravity conditions during a space flight. Symbolic dynamics and measures of complexity are proposed and applied to assess quantitatively the structural composition of bone tissue from...

  20. Statistical shape and appearance models of bones.

    Science.gov (United States)

    Sarkalkan, Nazli; Weinans, Harrie; Zadpoor, Amir A

    2014-03-01

    When applied to bones, statistical shape models (SSM) and statistical appearance models (SAM) respectively describe the mean shape and mean density distribution of bones within a certain population as well as the main modes of variations of shape and density distribution from their mean values. The availability of this quantitative information regarding the detailed anatomy of bones provides new opportunities for diagnosis, evaluation, and treatment of skeletal diseases. The potential of SSM and SAM has been recently recognized within the bone research community. For example, these models have been applied for studying the effects of bone shape on the etiology of osteoarthritis, improving the accuracy of clinical osteoporotic fracture prediction techniques, design of orthopedic implants, and surgery planning. This paper reviews the main concepts, methods, and applications of SSM and SAM as applied to bone. Copyright © 2013 Elsevier Inc. All rights reserved.

  1. A new zebrafish bone crush injury model

    Directory of Open Access Journals (Sweden)

    Sara Sousa

    2012-07-01

    While mammals have a limited capacity to repair bone fractures, zebrafish can completely regenerate amputated bony fin rays. Fin regeneration in teleosts has been studied after partial amputation of the caudal fin, which is not ideal to model human bone fractures because it involves substantial tissue removal, rather than local tissue injury. In this work, we have established a bone crush injury model in zebrafish adult caudal fin, which consists of the precise crush of bony rays with no tissue amputation. Comparing these two injury models, we show that the initial stages of injury response are the same regarding the activation of wound healing molecular markers. However, in the crush assay the expression of the blastema marker msxb appears later than during regeneration after amputation. Following the same trend, bone cells deposition and expression of genes involved in skeletogenesis are also delayed. We further show that bone and blood vessel patterning is also affected. Moreover, analysis of osteopontin and Tenascin-C reveals that they are expressed at later stages in crushed tissue, suggesting that in this case bone repair is prolonged for longer than in the case of regeneration after amputation. Due to the nature of the trauma inflicted, the crush injury model seems more similar to fracture bone repair in mammals than bony ray amputation. Therefore, the new model that we present here may help to identify the key processes that regulate bone fracture and contribute to improve bone repair in humans.

  2. Structural bone allograft fractures in oncological procedures.

    Science.gov (United States)

    Garcia-Coiradas, Javier; Garcia-Maroto, Roberto; Cebrian, Juan Luis; Lopez-Duran, Luis

    2015-11-01

    We report our experience analysing the risk of fracture amongst allografts in limb-preserving surgery for bone tumours. We retrospectively reviewed our experience with bone allograft and its major complications when used for limb -preserving operations for bone tumours. Forty-one structural allografts were performed in 39 patients between 1992 and 2012. Minimum follow-up was 20 months. Massive allografts have a high complication rate. Excluding infection and nonunion, five acute fractures were found. All fractures occurred after the graft-host junction was united. Local factors-such as graft preservation, weight bearing, fixation to the host or systemic factors such as adjuvant treatments (chemotherapy or radiotherapy)-influence fracture rate. In our study, four patients achieved consolidation with internal fixation and autologous iliac-crest graft, whilst only one required graft exchange. There is no general consensus as to when to treat fractures using open reduction and internal fixation or by exchanging the allograft. Higher fracture rate in relation to systemic treatment was found. Massive structural allograft reconstruction still has a place in limb-preserving surgery, with an acceptable fracture rate and a durable solution.

  3. Personalized models of bones based on radiographic photogrammetry.

    Science.gov (United States)

    Berthonnaud, E; Hilmi, R; Dimnet, J

    2009-07-01

    The radiographic photogrammetry is applied, for locating anatomical landmarks in space, from their two projected images. The goal of this paper is to define a personalized geometric model of bones, based uniquely on photogrammetric reconstructions. The personalized models of bones are obtained from two successive steps: their functional frameworks are first determined experimentally, then, the 3D bone representation results from modeling techniques. Each bone functional framework is issued from direct measurements upon two radiographic images. These images may be obtained using either perpendicular (spine and sacrum) or oblique incidences (pelvis and lower limb). Frameworks link together their functional axes and punctual landmarks. Each global bone volume is decomposed in several elementary components. Each volumic component is represented by simple geometric shapes. Volumic shapes are articulated to the patient's bone structure. The volumic personalization is obtained by best fitting the geometric model projections to their real images, using adjustable articulations. Examples are presented to illustrating the technique of personalization of bone volumes, directly issued from the treatment of only two radiographic images. The chosen techniques for treating data are then discussed. The 3D representation of bones completes, for clinical users, the information brought by radiographic images.

  4. Artificial composite bone as a model of human trabecular bone: the implant-bone interface.

    Science.gov (United States)

    Grant, J A; Bishop, N E; Götzen, N; Sprecher, C; Honl, M; Morlock, M M

    2007-01-01

    The use of artificial bones in implant testing has become popular due to their low variability and ready availability. However, friction coefficients, which are critical to load transfer in uncemented implants, have rarely been compared between human and artificial bone, particularly for wet and dry conditions. In this study, the static and dynamic friction coefficients for four commercially used titanium surfaces (polished, Al(2)O(3) blasted, plasma sprayed, beaded) acting on the trabecular component of artificial bones (Sawbones) were compared to those for human trabecular bone. Artificial bones were tested in dry and wet conditions and normal interface stress was varied (0.25, 0.5, 1.0MPa). Friction coefficients were mostly lower for artificial bones than real bone. In particular, static friction coefficients for the dry polished surface were 20% of those for real bone and 42-61% for the dry beaded surface, with statistical significance (alphaartificial bone models for pre-clinical implant testing that rely on interface load transfer with trabecular bone for mechanical integrity can be particularly sensitive to surface finish and lubrication conditions.

  5. Ossicular bone modeling in acute otitis media

    DEFF Research Database (Denmark)

    Salomonsen, Rasmus Lysholdt; Hermansson, Ann; Cayé-Thomasen, Per

    2010-01-01

    A number of middle ear diseases are associated with pathologic bone modeling, either formative or resorptive. As such, the pathogenesis of a sclerotic mastoid has been controversial for decades. Experimental studies on acute middle ear infection have shown progressive osteoneogenesis in the bone ...

  6. Digital Astronaut: Bone Remodeling Model

    Data.gov (United States)

    National Aeronautics and Space Administration — Significant progress has been made with regard to the plan outlined in the 2014 report for building in the effects of exercise induced loading on preserving bone...

  7. Mechanical Modelling of Cancellous Bone from their Microstructure

    Directory of Open Access Journals (Sweden)

    Ruiz–Cervantes O.

    2010-04-01

    Full Text Available In this paper is established a spongy bone bidimensional models methodology for its analysis by finite element software. The models are focused to represent the bone trabecular structure by Voronoi cells, using the coordinates of the porous center, contained within the bone structure, obtained by optical microscope images. Looking for a better geometrical similarity, it was assigned a thicker transversal area in the trabecula union zone, because has been reported that this factor gives a better approximation to experimental results. To feed the finite element models, compression test has been done to trabecular specimens, taking the maximum strain and maximum stress, to obtain the elastic modulus. By means of strained specimen images analysis, it has been established the structure collapse moment. It was when the 36% of total trabeculae failed. Finally it was obtained a tissue Young modulus of 323 [MPa] and with this value, the resistance variation in function of density and trabecular architecture.

  8. Maxillary Bone Regeneration Based on Nanoreservoirs Functionalized ε-Polycaprolactone Biomembranes in a Mouse Model of Jaw Bone Lesion

    Directory of Open Access Journals (Sweden)

    Marion Strub

    2018-01-01

    Full Text Available Current approaches of regenerative therapies constitute strategies for bone tissue reparation and engineering, especially in the context of genetical diseases with skeletal defects. Bone regeneration using electrospun nanofibers’ implant has the following objectives: bone neoformation induction with rapid healing, reduced postoperative complications, and improvement of bone tissue quality. In vivo implantation of polycaprolactone (PCL biomembrane functionalized with BMP-2/Ibuprofen in mouse maxillary defects was followed by bone neoformation kinetics evaluation using microcomputed tomography. Wild-Type (WT and Tabby (Ta mice were used to compare effects on a normal phenotype and on a mutant model of ectodermal dysplasia (ED. After 21 days, no effect on bone neoformation was observed in Ta treated lesion (4% neoformation compared to 13% in the control lesion. Between the 21st and the 30th days, the use of biomembrane functionalized with BMP-2/Ibuprofen in maxillary bone lesions allowed a significant increase in bone neoformation peaks (resp., +8% in mutant Ta and +13% in WT. Histological analyses revealed a neoformed bone with regular trabecular structure, areas of mineralized bone inside the membrane, and an improved neovascularization in the treated lesion with bifunctionalized membrane. In conclusion, PCL functionalized biomembrane promoted bone neoformation, this effect being modulated by the Ta bone phenotype responsible for an alteration of bone response.

  9. Quantifying bone structure, micro-architecture, and pathophysiology with MRI.

    Science.gov (United States)

    Singh, S; Bray, T J P; Hall-Craggs, M A

    2018-03-01

    The radiology of bone has been transformed by magnetic resonance imaging, which has the ability to interrogate bone's complex architecture and physiology. New techniques provide information about both the macrostructure and microstructure of bone ranging from micrometre detail to the whole skeleton. Furthermore functional information about bone physiology can be used to detect disease early before structural changes occur. The future of bone imaging is in quantifying the anatomical and functional information to diagnose and monitor disease more precisely. This review explores the state of the art in quantitative MRI bone imaging. Crown Copyright © 2018. Published by Elsevier Ltd. All rights reserved.

  10. Chemodectomas arising in temporal bone structures

    International Nuclear Information System (INIS)

    Dickens, W.J.; Million, R.R.; Cassisi, N.J.; Singleton, G.T.

    1982-01-01

    Eighteen patients with chemodectomas arising in temporal bone structures were evaluated and treated at the University of Florida. Seventeen patients have each been followed a minimum of 3 years. Patients were retrospectively staged as having ''local'' or ''advanced'' disease, depending on the presence or absence of bone destruction and/or cranial nerve involvement. Fourteen of the patients received radiation therapy as all or part of their therapy; 6 patients were treated with radiation therapy alone, 3 patients were irradiated immediately postoperatively for residual disease, and 5 patients had radiation therapy for recurrence after operation. They were treated with cobalt-60 radiation with doses ranging from 3760 to 5640 rad. All irradiated patients demonstrated evidence of tumor regression, and none have had tumor recurrence with followup of 3-12 years. Of the 8 patients with cranial nerve paralysis prior to therapy, 5 had return of function of 1 or more cranial nerves. One of 6 patients treated initially with radiation therapy had a complication, while 6 of 8 patients irradiated postoperatively had complications. None of the complications were fatal. Three patients treated by operation for early disease limited to the hypotympanum had the disease controlled for 11-12 years. Guidelines for the selection of initial therapy are discussed

  11. Cross-correlative 3D micro-structural investigation of human bone processed into bone allografts

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Atul Kumar [Centre for Research in Nanotechnology & Science, Indian Institute of Technology Bombay, Mumbai 400076 (India); Gajiwala, Astrid Lobo [Tissue Bank, Tata Memorial Hospital, Parel, Mumbai 400012 (India); Rai, Ratan Kumar [Centre of Biomedical Research, SGPGIMS Campus, Lucknow 226014 (India); Khan, Mohd Parvez [Division of Endocrinology, Center for Research in Anabolic Skeletal Targets in Health and Illness (ASTHI) CSIR-Central Drug Research Institute, Lucknow 226031 (India); Singh, Chandan [Centre of Biomedical Research, SGPGIMS Campus, Lucknow 226014 (India); Barbhuyan, Tarun [Division of Endocrinology, Center for Research in Anabolic Skeletal Targets in Health and Illness (ASTHI) CSIR-Central Drug Research Institute, Lucknow 226031 (India); Vijayalakshmi, S. [Centre for Research in Nanotechnology & Science, Indian Institute of Technology Bombay, Mumbai 400076 (India); Chattopadhyay, Naibedya [Division of Endocrinology, Center for Research in Anabolic Skeletal Targets in Health and Illness (ASTHI) CSIR-Central Drug Research Institute, Lucknow 226031 (India); Sinha, Neeraj, E-mail: neerajcbmr@gmail.com [Centre of Biomedical Research, SGPGIMS Campus, Lucknow 226014 (India); Kumar, Ashutosh, E-mail: ashutoshk@iitb.ac.in [Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai 400076 (India); Bellare, Jayesh R., E-mail: jb@iitb.ac.in [Centre for Research in Nanotechnology & Science, Indian Institute of Technology Bombay, Mumbai 400076 (India); Department of Chemical Engineering, Indian Institute of Technology Bombay, Mumbai 400076 (India)

    2016-05-01

    Bone allografts (BA) are a cost-effective and sustainable alternative in orthopedic practice as they provide a permanent solution for preserving skeletal architecture and function. Such BA however, must be processed to be disease free and immunologically safe as well as biologically and clinically useful. Here, we have demonstrated a processing protocol for bone allografts and investigated the micro-structural properties of bone collected from osteoporotic and normal human donor samples. In order to characterize BA at different microscopic levels, a combination of techniques such as Solid State Nuclear Magnetic Resonance (ssNMR), Scanning Electron Microscope (SEM), micro-computed tomography (μCT) and Thermal Gravimetric Analysis (TGA) were used for delineating the ultra-structural property of bone. ssNMR revealed the extent of water, collagen fine structure and crystalline order in the bone. These were greatly perturbed in the bone taken from osteoporotic bone donor. Among the processing methods analyzed, pasteurization at 60 °C and radiation treatment appeared to substantially alter the bone integrity. SEM study showed a reduction in Ca/P ratio and non-uniform distribution of elements in osteoporotic bones. μ-CT and MIMICS® (Materialize Interactive Medical Image Control System) demonstrated that pasteurization and radiation treatment affects the BA morphology and cause a shift in the HU unit. However, the combination of all these processes restored all-important parameters that are critical for BA integrity and sustainability. Cross-correlation between the various probes we used quantitatively demonstrated differences in morphological and micro-structural properties between BA taken from normal and osteoporotic human donor. Such details could also be instrumental in designing an appropriate bone scaffold. For the best restoration of bone microstructure and to be used as a biomaterial allograft, a step-wise processing method is recommended that preserves all

  12. Stress Distribution on Short Implants at Maxillary Posterior Alveolar Bone Model With Different Bone-to-Implant Contact Ratio: Finite Element Analysis.

    Science.gov (United States)

    Yazicioglu, Duygu; Bayram, Burak; Oguz, Yener; Cinar, Duygu; Uckan, Sina

    2016-02-01

    The aim of this study was to evaluate the stress distribution of the short dental implants and bone-to-implant contact ratios in the posterior maxilla using 3-dimensional (3D) finite element models. Two different 3D maxillary posterior bone segments were modeled. Group 1 was composed of a bone segment consisting of cortical bone and type IV cancellous bone with 100% bone-to-implant contact. Group 2 was composed of a bone segment consisting of cortical bone and type IV cancellous bone including spherical bone design and homogenous tubular hollow spaced structures with 30% spherical porosities and 70% bone-to-implant contact ratio. Four-millimeter-diameter and 5-mm-height dental implants were assumed to be osseointegrated and placed at the center of the segments. Lateral occlusal bite force (300 N) was applied at a 25° inclination to the implants long axis. The maximum von Mises stresses in cortical and cancellous bones and implant-abutment complex were calculated. The von Mises stress values on the implants and the cancellous bone around the implants of the 70% bone-to-implant contact group were almost 3 times higher compared with the values of the 100% bone-to-implant contact group. For clinical reality, use of the 70% model for finite element analysis simulation of the posterior maxilla region better represents real alveolar bone and the increased stress and strain distributions evaluated on the cortical and cancellous bone around the dental implants.

  13. [Bone tissue morphological structure in congenital deformations of the jaws].

    Science.gov (United States)

    Shishkanov, A V; Panin, M G; Shipkova, T P; Chumakov, A A; Komnova, Z D

    2001-01-01

    Morphological structure of bone tissue was studied in various types of congenital deformations of the jaws. Morphological changes in the bone with deformations and the severity of these disorders depended not so much on the type on the deformation, but mainly on its severity, which can be explained by a drastic increase of functional exercise because of impaired occlusion and impossibility of proper chewing. Decelerated weak restructuring of bone tissue and imperfect osteogenesis in deformed bone, similar in various types of deformations, were demonstrated on morphological material. These changes can affect the regenerative potential of the bone in operated zones.

  14. Bone cement allocation analysis in artificial cancellous bone structures

    Directory of Open Access Journals (Sweden)

    Ivan Zderic

    2017-01-01

    Conclusion: The simulated leakage path seemed to be the most important adverse injection factor influencing the uniformity of cement distribution. Another adverse factor causing dispersion of this distribution was represented by the simulated bone marrow. However, the rather uniform distribution of the totally injected cement amount, considered as one unit, could be ascribed to the medium viscosity of the used cement. Finally, with its short waiting time of 45 s, the stepwise injection procedure was shown to be ineffective in preventing cement leakage.

  15. Imaging Internal Structure of Long Bones Using Wave Scattering Theory.

    Science.gov (United States)

    Zheng, Rui; Le, Lawrence H; Sacchi, Mauricio D; Lou, Edmond

    2015-11-01

    An ultrasonic wavefield imaging method is developed to reconstruct the internal geometric properties of long bones using zero-offset data acquired axially on the bone surface. The imaging algorithm based on Born scattering theory is implemented with the conjugate gradient iterative method to reconstruct an optimal image. In the case of a multilayered velocity model, ray tracing through a smooth medium is used to calculate the traveled distance and traveling time. The method has been applied to simulated and real data. The results indicate that the interfaces of the top cortex are accurately imaged and correspond favorably to the original model. The reconstructed bottom cortex below the marrow is less accurate mainly because of the low signal-to-noise ratio. The current imaging method has successfully recovered the top cortical layer, providing a potential tool to investigate the internal structures of long bone cortex for osteoporosis assessment. Copyright © 2015 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

  16. Transgenic mouse models of metabolic bone disease.

    Science.gov (United States)

    McCauley, L K

    2001-07-01

    The approach of gene-targeted animal models is likely the most important experimental tool contributing to recent advances in skeletal biology. Modifying the expression of a gene in vivo, and the analysis of the consequences of the mutation, are central to the understanding of gene function during development and physiology, and therefore to our understanding of the gene's role in disease states. Researchers had been limited to animal models primarily involving pharmaceutical manipulations and spontaneous mutations. With the advent of gene targeting, however, animal models that impact our understanding of metabolic bone disease have evolved dramatically. Interestingly, some genes that were expected to yield dramatic phenotypes in bone, such as estrogen receptor-alpha or osteopontin, proved to have subtle phenotypes, whereas other genes, such as interleukin-5 or osteoprotegerin, were initially identified as having a role in bone metabolism via the analysis of their phenotype after gene ablation or overexpression. Particularly important has been the advance in knowledge of osteoblast and osteoclast independent and dependent roles via the selective targeting of genes and the consequent disruption of bone formation, bone resorption, or both. Our understanding of interactions of the skeletal system with other systems, ie, the vascular system and homeostatic controls of adipogenesis, has evolved via animal models such as the matrix gla protein, knock-out, and the targeted overexpression of Delta FosB. Challenging transgenic models such as the osteopontin-deficient mice with mediators of bone remodeling like parathyroid hormone and mechanical stimuli and extending phenotype characterization to mechanistic in vitro studies of primary bone cells is providing additional insight into the mechanisms involved in pathologic states and their potentials for therapeutic strategies. This review segregates characterization of transgenic models based on the category of gene altered

  17. Theoretical analysis of the spatio-temporal structure of bone multicellular units

    International Nuclear Information System (INIS)

    Buenzli, P R; Pivonka, P; Gardiner, B S; Smith, D W; Dunstan, C R; Mundy, G R

    2010-01-01

    Bone multicellular units (BMUs) maintain the viability of the skeletal tissue by coordinating locally the sequence of bone resorption and bone formation performed by cells of the osteoclastic and osteoblastic lineage. Understanding the emergence and the net bone balance of such structured microsystems out of the complex network of biochemical interactions between bone cells is fundamental for many bone-related diseases and the evaluation of fracture risk. Based on current experimental knowledge, we propose a spatio-temporal continuum model describing the interactions of osteoblastic and osteoclastic cells. We show that this model admits travelling-wave-like solutions with well-confined cell profiles upon specifying external conditions mimicking the environment encountered in cortical bone remodelling. The shapes of the various cell concentration profiles within this travelling structure are intrinsically linked to the parameters of the model such as differentiation, proliferation, and apoptosis rates of bone cells. The internal structure of BMUs is reproduced, allowing for experimental calibration. The spatial distribution of the key regulatory factors can also be exhibited, which in diseased states could give hints as to the biochemical agent most accountable for the disorder.

  18. Hierarchical Structure of Articular Bone-Cartilage Interface and Its Potential Application for Osteochondral Tissue Engineering

    Science.gov (United States)

    Bian, Weiguo; Qin, Lian; Li, Dichen; Wang, Jin; Jin, Zhongmin

    2010-09-01

    The artificial biodegradable osteochondral construct is one of mostly promising lifetime substitute in the joint replacement. And the complex hierarchical structure of natural joint is important in developing the osteochondral construct. However, the architecture features of the interface between cartilage and bone, in particular those at the micro-and nano-structural level, remain poorly understood. This paper investigates these structural data of the cartilage-bone interface by micro computerized tomography (μCT) and Scanning Electron Microscope (SEM). The result of μCT shows that important bone parameters and the density of articular cartilage are all related to the position in the hierarchical structure. The conjunctions of bone and cartilage were defined by SEM. All of the study results would be useful for the design of osteochondral construct further manufactured by nano-tech. A three-dimensional model with gradient porous structure is constructed in the environment of Pro/ENGINEERING software.

  19. Finite Element Analysis of the Hierarchical Structure of Human Bone

    National Research Council Canada - National Science Library

    Dolloff, Katherine

    2003-01-01

    .... Finally, the effective stiffness of the bone was estimated. In order to determine the stiffness of the collagen fiber, a three-dimensional finite element model was developed and a simple analytical model was derived...

  20. Structure analysis of tabecular bone in the diagnosis of osteoporosis

    International Nuclear Information System (INIS)

    Link, T.M.; Meier, N.; Waldt, S.; Lin, J.C.; Newitt, D.; Majumdar, S.

    1998-01-01

    Osteoporosis is characteried by reduced bone mass and a deterioration of bone structure which results in an increased fracture risk. The purpose of this review is to evaluate structure analysis techniques in the diagnosis of osteoporosis. Several imaging techniques were applied to analyze trabecular bone, such as conventional radiography, high-resolution computed tomography (HR-CT) and high-resolution magnetic resonance imaging (HR-MRI). The best results were obtained using high-resolution tomographic techniques. The highest spatial resolutions in vivo were achieved using HR-MRI. These studies show that texture parameters and bone mineral density predict bone strength and osteoporotic fractures in a complementary fashion. Combining both techniques yields the best results in the diagnosis of osteoporosis. (orig.) [de

  1. Composites structures for bone tissue reconstruction

    Energy Technology Data Exchange (ETDEWEB)

    Neto, W.; Santos, João [Universidade Federal de São Carlos, Departament of Materials Engineering - Rd. Washington Luis, Km 235, 13565-905, São Carlos-SP (Brazil); Avérous, L.; Schlatter, G.; Bretas, Rosario, E-mail: bretas@ufscar.br [Université de Strasbourg, ECPM-LIPHT - 25 rue Becquerel, 67087, Strasbourg (France)

    2015-05-22

    The search for new biomaterials in the bone reconstitution field is growing continuously as humane life expectation and bone fractures increase. For this purpose, composite materials with biodegradable polymers and hydroxyapatite (HA) have been used. A composite material formed by a film, nanofibers and HA has been made. Both, the films and the non-woven mats of nanofibers were formed by nanocomposites made of butylene adipate-co-terephthalate (PBAT) and HA. The techniques used to produce the films and nanofibers were spin coating and electrospinning, respectively. The composite production and morphology were evaluated. The composite showed an adequate morphology and fibers size to be used as scaffold for cell growth.

  2. Composites structures for bone tissue reconstruction

    International Nuclear Information System (INIS)

    Neto, W.; Santos, João; Avérous, L.; Schlatter, G.; Bretas, Rosario

    2015-01-01

    The search for new biomaterials in the bone reconstitution field is growing continuously as humane life expectation and bone fractures increase. For this purpose, composite materials with biodegradable polymers and hydroxyapatite (HA) have been used. A composite material formed by a film, nanofibers and HA has been made. Both, the films and the non-woven mats of nanofibers were formed by nanocomposites made of butylene adipate-co-terephthalate (PBAT) and HA. The techniques used to produce the films and nanofibers were spin coating and electrospinning, respectively. The composite production and morphology were evaluated. The composite showed an adequate morphology and fibers size to be used as scaffold for cell growth

  3. Analysis of the structure and strength of bones in celiac disease patients.

    Science.gov (United States)

    Ferretti, José; Mazure, Roberto; Tanoue, Patricio; Marino, Alicia; Cointry, Gustavo; Vazquez, Horacio; Niveloni, Sonia; Pedreira, Silvia; Mauriño, Eduardo; Zanchetta, José; Bai, Julio C

    2003-02-01

    The aim of this study was to gain insight into the pathogenesis of bone mass loss and weakening affecting patients with celiac disease, according to the new concepts of bone structure/strength and muscle/bone interrelationships. We studied serum variables and tomographic indicators of bone structure and strength and regional muscle masses in a series of patients at diagnosis and after 1 yr on a gluten-free diet and in gender- and age-matched controls. At diagnosis, serum levels of calcium and vitamin D were low, and indicators of parathyroid hormone activity and bone formation and resorption were increased. All these parameters were normalized by treatment. Peripheral quantitative CT scans of the distal radius revealed that cortical bone was generally more affected than trabecular bone. The cross-sectional area (CSA) and the volumetric mineral content and density of cortical bone (indicators of cortical tissue mass and mechanical quality), and moments of inertia (CSMI, indicator of the bone architectural design) were in the lower end of normal range in men, and below that in 50% of women. In men, the CSMI/CSA ratio (indicator of the architectural efficiency of distribution of the available cortical tissue) was lower than expected and remained unchanged after treatment. In women, the baseline ratio was normal, but both the ratio and the CSMI were low at diagnosis and normalized after treatment. Both baseline values and the treatment-induced changes of cortical and trabecular bone in the radius and the axis (L3) correlated inversely with serum parathyroid hormone levels. Baseline values or changes in the mineral content of the vertebral bone correlated with the CSA of psoas and spine-extensor muscles. Multiple regression analyses showed that metabolic and mechanical parameters were independent determinants of different aspects of the vertebral bone weakening. Our results show that bone weakening in celiac disease might result from both 1) a metabolic disturbances of

  4. 3D artificial bones for bone repair prepared by computed tomography-guided fused deposition modeling for bone repair.

    Science.gov (United States)

    Xu, Ning; Ye, Xiaojian; Wei, Daixu; Zhong, Jian; Chen, Yuyun; Xu, Guohua; He, Dannong

    2014-09-10

    The medical community has expressed significant interest in the development of new types of artificial bones that mimic natural bones. In this study, computed tomography (CT)-guided fused deposition modeling (FDM) was employed to fabricate polycaprolactone (PCL)/hydroxyapatite (HA) and PCL 3D artificial bones to mimic natural goat femurs. The in vitro mechanical properties, in vitro cell biocompatibility, and in vivo performance of the artificial bones in a long load-bearing goat femur bone segmental defect model were studied. All of the results indicate that CT-guided FDM is a simple, convenient, relatively low-cost method that is suitable for fabricating natural bonelike artificial bones. Moreover, PCL/HA 3D artificial bones prepared by CT-guided FDM have more close mechanics to natural bone, good in vitro cell biocompatibility, biodegradation ability, and appropriate in vivo new bone formation ability. Therefore, PCL/HA 3D artificial bones could be potentially be of use in the treatment of patients with clinical bone defects.

  5. Transgenic Mouse Model for Reducing Oxidative Damage in Bone

    Science.gov (United States)

    Schreurs, Ann-Sofie; Torres, S.; Truong, T.; Moyer, E. L.; Kumar, A.; Tahimic, Candice C. G.; Alwood, J. S.; Limoli, C. L.; Globus, R. K.

    2016-01-01

    Bone loss can occur due to many challenges such age, radiation, microgravity, and Reactive Oxygen Species (ROS) play a critical role in bone resorption by osteoclasts (Bartell et al. 2014). We hypothesize that suppression of excess ROS in skeletal cells, both osteoblasts and osteoclasts, regulates skeletal growth and remodeling. To test our hypothesis, we used transgenic mCAT mice which overexpress the human anti-oxidant catalase gene targeted to the mitochondria, the main site for endogenous ROS production. mCAT mice have a longer life-span than wildtype controls and have been used to study various age-related disorders. To stimulate remodeling, 16 week old mCAT mice or wildtype mice were exposed to treatment (hindlimb-unloading and total body-irradiation) or sham treatment conditions (control). Tissues were harvested 2 weeks later for skeletal analysis (microcomputed tomography), biochemical analysis (gene expression and oxidative damage measurements), and ex vivo bone marrow derived cell culture (osteoblastogenesis and osteoclastogenesis). mCAT mice expressed the transgene and displayed elevated catalase activity in skeletal tissue and marrow-derived osteoblasts and osteoclasts grown ex vivo. In addition, when challenged with treatment, bone tissues from wildtype mice showed elevated levels of malondialdehyde (MDA), indicating oxidative damage) whereas mCAT mice did not. Correlation analysis revealed that increased catalase activity significantly correlated with decreased MDA levels and that increased oxidative damage correlated with decreased percent bone volume (BVTV). In addition, ex-vivo cultured osteoblast colony growth correlated with catalase activity in the osteoblasts. Thus, we showed that these transgenic mice can be used as a model to study the relationship between markers of oxidative damage and skeletal properties. mCAT mice displayed reduced BVTV and trabecular number relative to wildtype mice, as well as increased structural model index in the

  6. Influence of Mebivid on the Structural and Functional State of Bone Tissue in Experimental Nutritional Osteoporosis

    Directory of Open Access Journals (Sweden)

    A.T. Brusko

    2015-10-01

    Full Text Available To determine the impact of domestic combined preparation mebivid containing vitamin D3 and bisphosphonate on the normalization of the structural and functional state of epiphyseal cartilage and bone tissue, we have conducted an experimental study on 30 Wistar rats weighing 90 ± 5 g. We used nutritional model of osteoporosis. Histomorphologic and osteometric studies were carried out, bone ash content was determined. The study found that mebivid effectively influences the normalization of disorders of the structural and functional state of epiphyseal cartilage and bone tissue in the nutritional osteoporosis in rats. Experimental studies demonstrate the feasibility of using a combined drug mebivid in the treatment of orthopedic diseases associated with impaired longitudinal growth, increase in thickness and structural and functional state of bone tissue.

  7. Association Between Insulin Resistance and Bone Structure in Nondiabetic Postmenopausal Women

    Science.gov (United States)

    Finkelstein, Joel S.; Bouxsein, Mary L.; Yu, Elaine W.

    2016-01-01

    Context: The clinical consequences of insulin resistance and hyperinsulinemia on bone remain largely unknown. Objective: The objective of the study was to evaluate the effect of insulin resistance on peripheral bone geometry, volumetric bone mineral density (vBMD), bone microarchitecture, and estimated bone strength. Design, Setting, and Participants: This cross-sectional study included 146 postmenopausal, nondiabetic Caucasian women (mean age 60.3 ± 2.7 y) who were participating in the Study of Women's Health Across the Nation. Interventions: There were no interventions. Main Outcome Measures: High-resolution peripheral quantitative computed tomography was used to assess bone density and microstructure at the distal radius and tibia. Fasting insulin and glucose were measured and insulin resistance was estimated using homeostasis model assessment of insulin resistance (HOMA-IR), with higher values indicating greater insulin resistance. Results: There was a negative association between HOMA-IR and bone size and a positive association between HOMA-IR and total vBMD, trabecular vBMD, trabecular thickness, and cortical thickness at the radius and tibia. These relationships remained, even after adjusting for body weight and other potential covariates (eg, time since menopause, cigarette smoking, physical activity, prior use of osteoporosis medications or glucocorticoids). Conclusions: In nondiabetic, postmenopausal women, insulin resistance was associated with smaller bone size, greater volumetric bone mineral density, and generally favorable bone microarchitecture at weight-bearing and nonweight-bearing skeletal sites. These associations were independent of body weight and other potential covariates, suggesting that hyperinsulinemia directly affects bone structure independent of obesity and may explain, in part, the higher trabecular bone density and favorable trabecular microarchitecture seen in individuals with type 2 diabetes mellitus. PMID:27243136

  8. Assessment of global morphological and topological changes in trabecular structure under the bone resorption process

    Science.gov (United States)

    Sidorenko, Irina N.; Bauer, Jan; Monetti, Roberto; Baum, Thomas; Rummeny, Ernst J.; Eckstein, Felix; Matsuura, Maiko; Lochmueller, Eva-Maria; Zysset, Philippe K.; Raeth, Christoph W.

    2012-03-01

    Osteoporosis is a frequent skeletal disease characterised both by loss of bone mineral mass and deterioration of cancellous bone micro-architecture. It can be caused by mechanical disuse, estrogen deficiency or natural age-related resorption process. Numerical analysis of high-resolution images of the trabecular network is recognised as a powerful tool for assessment of structural characteristics. Using μCT images of 73 thoracic and 78 lumbar human vertebral specimens in vitro with isotropic resolution of 26μm we simulate bone atrophy as random resorption of bone surface voxels. Global morphological and topological characteristics provided by four Minkowski Functionals (MF) are calculated for two numerical resorption models with and without conservation of global topological connectivity of the trabecular network, which simulates different types of bone loss in osteoporosis, as it has been described in males and females. Diagnostic performance of morphological and topological characteristics as a function of relative bone loss is evaluated by a correlation analysis with respect to experimentally measured Maximum Compressive Strength (MCS). In both resorption models the second MF, which coincides with bone surface fraction BS/TV, demonstrates almost constant value of Pearson's correlation coefficient with respect to the relative bone loss ▵BV/TV. This morphological characteristic does not vary considerably under age-related random resorption and can be used for predicting bone strength in the elderly. The third and fourth MF demonstrate an increasing correlation coefficients with MCS after applying random bone surface thinning without preserving topological connectivity, what can be used for improvement of evaluation of the current state of the structure.

  9. The Structure and Function of Non-Collagenous Bone Proteins

    Science.gov (United States)

    Hook, Magnus; McQuillan, David J.

    1997-01-01

    The research done under the cooperative research agreement for the project titled 'The structure and function of non-collagenous bone proteins' represented the first phase of an ongoing program to define the structural and functional relationships of the principal noncollagenous proteins in bone. An ultimate goal of this research is to enable design and execution of useful pharmacological compounds that will have a beneficial effect in treatment of osteoporosis, both land-based and induced by long-duration space travel. The goals of the now complete first phase were as follows: 1. Establish and/or develop powerful recombinant protein expression systems; 2. Develop and refine isolation and purification of recombinant proteins; 3. Express wild-type non-collagenous bone proteins; 4. Express site-specific mutant proteins and domains of wild-type proteins to enhance likelihood of crystal formation for subsequent solution of structure.

  10. Strength through structure: visualization and local assessment of the trabecular bone structure

    Energy Technology Data Exchange (ETDEWEB)

    Raeth, C; Monetti, R; Bauer, J; Sidorenko, I [Max-Planck Institut fuer Extraterrestrische Physik, Giessenbachstrasse 1, 85748 Garching (Germany); Mueller, D [Department of Radiology, Technische Universitaet Muenchen, Klinikum rechts der Isar, Ismaninger Strasse 22, 81675 Munich (Germany); Matsuura, M [Institute of Anatomy, Ludwig Maximilians Universitaet Muenchen, Pettenkoferstrasse 11, 80336 Muenchen (Germany); Lochmueller, E-M [Department of Gynaecology I, Ludwig Maximilians Universitaet Muenchen, Maistrasse 11, 80337 Muenchen (Germany); Zysset, P [Institute for Lightweight Design and Structural Biomechanics, Vienna University of Technology (TU-Wien), Gusshausstrasse 27-29, 1040 Wien (Austria); Eckstein, F [Paracelsus Medical University Salzburg, Strubergasse 21, 5020 Salzburg (Austria)], E-mail: cwr@mpe.mpg.de

    2008-12-15

    The visualization and subsequent assessment of the inner human bone structures play an important role for better understanding the disease- or drug-induced changes of bone in the context of osteoporosis giving prospect for better predictions of bone strength and thus of the fracture risk of osteoporotic patients. In this work, we show how the complex trabecular bone structure can be visualized using {mu}CT imaging techniques at an isotropic resolution of 26 {mu}m. We quantify these structures by calculating global and local topological and morphological measures, namely Minkowski functionals (MFs) and utilizing the (an-)isotropic scaling index method (SIM) and by deriving suitable texture measures based on MF and SIM. Using a sample of 151 specimens taken from human vertebrae in vitro, we correlate the texture measures with the mechanically measured maximum compressive strength (MCS), which quantifies the strength of the bone probe, by using Pearson's correlation coefficient. The structure parameters derived from the local measures yield good correlations with the bone strength as measured in mechanical tests. We investigate whether the performance of the texture measures depends on the MCS value by selecting different subsamples according to MCS. Considering the whole sample the results for the newly defined parameters are better than those obtained for the standard global histomorphometric parameters except for bone volume/total volume (BV/TV). If a subsample consisting only of weak bones is analysed, the local structural analysis leads to similar and even better correlations with MCS as compared to BV/TV. Thus, the MF and SIM yield additional information about the stability of the bone especially in the case of weak bones, which corroborates the hypothesis that the bone structure (and not only its mineral mass) constitutes an important component of bone stability.

  11. Automatic analysis of trabecular bone structure from knee MRI

    DEFF Research Database (Denmark)

    Marques, Joselene; Granlund, Rabia; Lillholm, Martin

    2012-01-01

    We investigated the feasibility of quantifying osteoarthritis (OA) by analysis of the trabecular bone structure in low-field knee MRI. Generic texture features were extracted from the images and subsequently selected by sequential floating forward selection (SFFS), following a fully automatic......, uncommitted machine-learning based framework. Six different classifiers were evaluated in cross-validation schemes and the results showed that the presence of OA can be quantified by a bone structure marker. The performance of the developed marker reached a generalization area-under-the-ROC (AUC) of 0...

  12. Multiscale damage and strength of lamellar bone modeled by cohesive finite elements.

    Science.gov (United States)

    Hamed, Elham; Jasiuk, Iwona

    2013-12-01

    A computational multiscale model of damage mechanisms and strength of lamellar bone is presented. The analysis incorporates the hierarchical structure of bone spanning the nanoscale (mineralized collagen fibril), the sub-microscale (single lamella) and the microscale (lamellar structure) levels. Due to the presence of several constituents (collagen, hydroxyapatite minerals, and non-collagenous proteins) and the different microstructural features at each scale, various deformation and failure mechanisms occur in bone at its several levels of hierarchy. The model takes into account the dominant damage mechanisms at the above mentioned three scales and predicts the strength of bone by using a cohesive finite element method. Elastic moduli of bone at these three different scales are also obtained as part of these calculations. The obtained modeling results compare well with other theoretical and experimental data available in the literature. © 2013 Elsevier Ltd. All rights reserved.

  13. Reinforcements in avian wing bones: Experiments, analysis, and modeling.

    Science.gov (United States)

    Novitskaya, E; Ruestes, C J; Porter, M M; Lubarda, V A; Meyers, M A; McKittrick, J

    2017-12-01

    Almost all species of modern birds are capable of flight; the mechanical competency of their wings and the rigidity of their skeletal system evolved to enable this outstanding feat. One of the most interesting examples of structural adaptation in birds is the internal structure of their wing bones. In flying birds, bones need to be sufficiently strong and stiff to withstand forces during takeoff, flight, and landing, with a minimum of weight. The cross-sectional morphology and presence of reinforcing structures (struts and ridges) found within bird wing bones vary from species to species, depending on how the wings are utilized. It is shown that both morphology and internal features increases the resistance to flexure and torsion with a minimum weight penalty. Prototypes of reinforcing struts fabricated by 3D printing were tested in diametral compression and torsion to validate the concept. In compression, the ovalization decreased through the insertion of struts, while they had no effect on torsional resistance. An elastic model of a circular ring reinforced by horizontal and vertical struts is developed to explain the compressive stiffening response of the ring caused by differently oriented struts. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Sclerostin Antibody Reverses Bone Loss by Increasing Bone Formation and Decreasing Bone Resorption in a Rat Model of Male Osteoporosis.

    Science.gov (United States)

    Li, Xiaodong; Ominsky, Michael S; Villasenor, Kelly S; Niu, Qing-Tian; Asuncion, Frank J; Xia, Xuechun; Grisanti, Mario; Wronski, Thomas J; Simonet, W Scott; Ke, Hua Zhu

    2018-01-01

    Sclerostin antibody (Scl-Ab) restored bone mass and strength in the ovariectomized rat model of postmenopausal osteoporosis. Increased bone mineral density (BMD) and decreased skeletal fragility fracture risk have been reported in postmenopausal osteoporotic women receiving Scl-Ab. In males, loss of androgen leads to rapid decreases in BMD and an increased risk of fragility fractures. We hypothesized that Scl-Ab could reverse the loss of bone mass and strength caused by androgen ablation in the orchiectomized (ORX) rat model of male osteoporosis. We treated 9-month-old ORX Sprague Dawley rats (3 months after ORX) subcutaneously twice weekly with vehicle or Scl-Ab (5 or 25 mg/kg) for 6 weeks (n = 10 per group). Both doses of Scl-Ab fully reversed the BMD deficit in the lumbar spine and femur and tibia in ORX rats. Microcomputed tomography showed that the bone mass in the fifth lumbar vertebral body, femur diaphysis, and femoral neck were dose-dependently restored by Scl-Ab. The bone strength at these sites increased significantly with Scl-Ab to levels matching those of sham-operated controls and correlated positively with improvements in bone mineral content, demonstrating bone quality maintenance. Dynamic histomorphometry of the tibial diaphysis and second lumbar vertebral body demonstrated that Scl-Ab significantly increased bone formation on periosteal, endocortical, and trabecular surfaces and significantly decreased bone resorption on endocortical and trabecular surfaces. The effects of Scl-Ab on increasing bone formation and decreasing bone resorption led to restoration of bone mass and strength in androgen-deficient rats. These findings support the ongoing evaluation of Scl-Ab as a potential therapeutic agent for osteoporosis in men. Copyright © 2018 Endocrine Society.

  15. Sclerostin antibody treatment increases bone formation, bone mass, and bone strength in a rat model of postmenopausal osteoporosis.

    Science.gov (United States)

    Li, Xiaodong; Ominsky, Michael S; Warmington, Kelly S; Morony, Sean; Gong, Jianhua; Cao, Jin; Gao, Yongming; Shalhoub, Victoria; Tipton, Barbara; Haldankar, Raj; Chen, Qing; Winters, Aaron; Boone, Tom; Geng, Zhaopo; Niu, Qing-Tian; Ke, Hua Zhu; Kostenuik, Paul J; Simonet, W Scott; Lacey, David L; Paszty, Chris

    2009-04-01

    The development of bone-rebuilding anabolic agents for potential use in the treatment of bone loss conditions, such as osteoporosis, has been a long-standing goal. Genetic studies in humans and mice have shown that the secreted protein sclerostin is a key negative regulator of bone formation, although the magnitude and extent of sclerostin's role in the control of bone formation in the aging skeleton is still unclear. To study this unexplored area of sclerostin biology and to assess the pharmacologic effects of sclerostin inhibition, we used a cell culture model of bone formation to identify a sclerostin neutralizing monoclonal antibody (Scl-AbII) for testing in an aged ovariectomized rat model of postmenopausal osteoporosis. Six-month-old female rats were ovariectomized and left untreated for 1 yr to allow for significant estrogen deficiency-induced bone loss, at which point Scl-AbII was administered for 5 wk. Scl-AbII treatment in these animals had robust anabolic effects, with marked increases in bone formation on trabecular, periosteal, endocortical, and intracortical surfaces. This not only resulted in complete reversal, at several skeletal sites, of the 1 yr of estrogen deficiency-induced bone loss, but also further increased bone mass and bone strength to levels greater than those found in non-ovariectomized control rats. Taken together, these preclinical results establish sclerostin's role as a pivotal negative regulator of bone formation in the aging skeleton and, furthermore, suggest that antibody-mediated inhibition of sclerostin represents a promising new therapeutic approach for the anabolic treatment of bone-related disorders, such as postmenopausal osteoporosis.

  16. Regenerative capacity of augmented bone in rat calvarial guided bone augmentation model.

    Science.gov (United States)

    Kubota, Tatsuya; Hasuike, Akira; Ozawa, Yasumasa; Yamamoto, Takanobu; Tsunori, Katsuyoshi; Yamada, Yutaka; Sato, Shuichi

    2017-04-01

    Guided bone regeneration (GBR) is the most widely used technique to regenerate and augment bones. Even though augmented bones (ABs) have been examined histologically in many studies, few studies have been conducted to examine the biological potential of these bones and the healing dynamics following their use. Moreover, whether the bone obtained from the GBR procedure possesses the same functions as the existing autogenous bone is uncertain. In particular, little attention has been paid to the regenerative ability of GBR bone. Therefore, the present study histologically evaluated the regenerative capacity of AB in the occlusive space of a rat guided bone augmentation (GBA) model. The calvaria of 30 rats were exposed, and plastic caps were placed on the right of the calvaria in 10 of the 30 rats. After a 12-week healing phase, critical-sized calvarial bone defects (diameter: 5.0 mm) were trephined into the dorsal parietal bone on the left of the calvaria. Bone particles were harvested from the AB or the cortical bone (CB) using a bone scraper and transplanted into the critical defects. The newly generated bone at the defects' edge was evaluated using micro-computed tomography (micro-CT) and histological sections. In the micro-CT analysis, the radiopacity in both the augmented and the CB groups remained high throughout the observational period. In the histological analysis, the closure rate of the CB was significantly higher than in the AB group. The numbers of cells positive for runt-related transcription factor 2 (Runx2) and tartrate-resistant acid phosphatase (TRAP) in the AB group were larger than in the CB group. The regenerative capacity of AB in the occlusive space of the rat GBA model was confirmed. Within the limitations of this study, the regenerative ability of the AB particulate transplant was inferior to that of the CB particulate transplant.

  17. DNA and bone structure preservation in medieval human skeletons.

    Science.gov (United States)

    Coulson-Thomas, Yvette M; Norton, Andrew L; Coulson-Thomas, Vivien J; Florencio-Silva, Rinaldo; Ali, Nadir; Elmrghni, Samir; Gil, Cristiane D; Sasso, Gisela R S; Dixon, Ronald A; Nader, Helena B

    2015-06-01

    Morphological and ultrastructural data from archaeological human bones are scarce, particularly data that have been correlated with information on the preservation of molecules such as DNA. Here we examine the bone structure of macroscopically well-preserved medieval human skeletons by transmission electron microscopy and immunohistochemistry, and the quantity and quality of DNA extracted from these skeletons. DNA technology has been increasingly used for analyzing physical evidence in archaeological forensics; however, the isolation of ancient DNA is difficult since it is highly degraded, extraction yields are low and the co-extraction of PCR inhibitors is a problem. We adapted and optimised a method that is frequently used for isolating DNA from modern samples, Chelex(®) 100 (Bio-Rad) extraction, for isolating DNA from archaeological human bones and teeth. The isolated DNA was analysed by real-time PCR using primers targeting the sex determining region on the Y chromosome (SRY) and STR typing using the AmpFlSTR(®) Identifiler PCR Amplification kit. Our results clearly show the preservation of bone matrix in medieval bones and the presence of intact osteocytes with well preserved encapsulated nuclei. In addition, we show how effective Chelex(®) 100 is for isolating ancient DNA from archaeological bones and teeth. This optimised method is suitable for STR typing using kits aimed specifically at degraded and difficult DNA templates since amplicons of up to 250bp were successfully amplified. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  18. Obesity-related changes in bone structural and material properties in hyperphagic OLETF rats and protection by voluntary wheel running

    Science.gov (United States)

    We conducted a study to examine how the development of obesity and the associated insulin resistance affect bone structural and material properties, and bone formation and resorption markers in the Otsuka Long-Evans Tokushima Fatty (OLETF) rat model. This was a 36-week study of sedentary, hyperphag...

  19. The Digital Astronaut Project Computational Bone Remodeling Model (Beta Version) Bone Summit Summary Report

    Science.gov (United States)

    Pennline, James; Mulugeta, Lealem

    2013-01-01

    Under the conditions of microgravity, astronauts lose bone mass at a rate of 1% to 2% a month, particularly in the lower extremities such as the proximal femur [1-3]. The most commonly used countermeasure against bone loss in microgravity has been prescribed exercise [4]. However, data has shown that existing exercise countermeasures are not as effective as desired for preventing bone loss in long duration, 4 to 6 months, spaceflight [1,3,5,6]. This spaceflight related bone loss may cause early onset of osteoporosis to place the astronauts at greater risk of fracture later in their lives. Consequently, NASA seeks to have improved understanding of the mechanisms of bone demineralization in microgravity in order to appropriately quantify this risk, and to establish appropriate countermeasures [7]. In this light, NASA's Digital Astronaut Project (DAP) is working with the NASA Bone Discipline Lead to implement well-validated computational models to help predict and assess bone loss during spaceflight, and enhance exercise countermeasure development. More specifically, computational modeling is proposed as a way to augment bone research and exercise countermeasure development to target weight-bearing skeletal sites that are most susceptible to bone loss in microgravity, and thus at higher risk for fracture. Given that hip fractures can be debilitating, the initial model development focused on the femoral neck. Future efforts will focus on including other key load bearing bone sites such as the greater trochanter, lower lumbar, proximal femur and calcaneus. The DAP has currently established an initial model (Beta Version) of bone loss due to skeletal unloading in femoral neck region. The model calculates changes in mineralized volume fraction of bone in this segment and relates it to changes in bone mineral density (vBMD) measured by Quantitative Computed Tomography (QCT). The model is governed by equations describing changes in bone volume fraction (BVF), and rates of

  20. Repairing rabbit radial defects by combining bone marrow stroma stem cells with bone scaffold material comprising a core-cladding structure.

    Science.gov (United States)

    Wu, H; Liu, G H; Wu, Q; Yu, B

    2015-10-05

    We prepared a bone scaffold material comprising a PLGA/β-TCP core and a Type I collagen cladding, and recombined it with bone marrow stroma stem cells (BMSCs) to evaluate its potential for use in bone tissue engineering by in vivo and in vitro experiments. PLGA/β-TCP without a cladding was used for comparison. The adherence rate of the BMSCs to the scaffold was determined by cell counting. Cell proliferation rate was determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide method. The osteogenic capability was evaluated by alkaline phosphatase activity. The scaffold materials were recombined with the BMSCs and implanted into a large segmental rabbit radial defect model to evaluate defect repair. Osteogenesis was assessed in the scaffold materials by histological and double immunofluorescence labeling, etc. The adherence number, proliferation number, and alkaline phosphatase expression of the cells on the bone scaffold material with core-cladding structure were significantly higher than the corresponding values in the PLGA/β-TCP composite scaffold material (P structure completely degraded at the bone defect site and bone formation was completed. The rabbit large sentimental radial defect was successfully repaired. The degradation and osteogenesis rates matched well. The bone scaffold with core-cladding structure exhibited better osteogenic activity and capacity to repair a large segmental bone defect compared to the PLGA/β-TCP composite scaffold. The bone scaffold with core-cladding structure has excellent physical properties and biocompatibility. It is an ideal scaffold material for bone tissue engineering.

  1. Bone malformations in Proteus syndrome: an analysis of bone structural changes and their evolution during growth

    Energy Technology Data Exchange (ETDEWEB)

    Pazzaglia, Ugo E.; Bonaspetti, Giovanni; Ranchetti, Federico [University of Brescia Spedali Civili di Brescia, Orthopaedic Clinic, Brescia (Italy); Beluffi, Giampiero [Fondazione I.R.C.C.S. Policlinico San Matteo, Pediatric Radiology Department, Pavia (Italy)

    2007-08-15

    The radiographic follow-up of a patient with Proteus syndrome is presented. Review of radiographs obtained at 3 years 10 months, 10 years, and 17 years 8 months indicated that the rate of growth in length of the oversized tubular bones of the hands was similar to that of the normal bones of the same hand. This observation supports the view that the primary lesion occurs in the early embryonic period, when the limb bud mesenchyme cells condense and cartilage differentiates producing oversized cartilage anlages, rather than being a defect of bone cell-mediated apposition and modelling processes of bone. Additional radiographs of the pelvis and spine were obtained at age 4 years 10 months and head CT at 8 years 10 months. This pathogenetic mechanism fits well with the hypothesis of somatic mosaicism, which is at present the most credible explanation for the aetiology of Proteus syndrome. Other skeletal malformations recognized as typical of the syndrome can be interpreted as secondary adaptations to the altered mechanical conditions induced by overgrowth of bones. (orig.)

  2. Experimentally-based multiscale model of the elastic moduli of bovine trabecular bone and its constituents.

    Science.gov (United States)

    Hamed, Elham; Novitskaya, Ekaterina; Li, Jun; Jasiuk, Iwona; McKittrick, Joanna

    2015-09-01

    The elastic moduli of trabecular bone were modeled using an analytical multiscale approach. Trabecular bone was represented as a porous nanocomposite material with a hierarchical structure spanning from the collagen-mineral level to the trabecular architecture level. In parallel, compression testing was done on bovine femoral trabecular bone samples in two anatomical directions, parallel to the femoral neck axis and perpendicular to it, and the measured elastic moduli were compared with the corresponding theoretical results. To gain insights on the interaction of collagen and minerals at the nanoscale, bone samples were deproteinized or demineralized. After such processing, the treated samples remained as self-standing structures and were tested in compression. Micro-computed tomography was used to characterize the hierarchical structure of these three bone types and to quantify the amount of bone porosity. The obtained experimental data served as inputs to the multiscale model and guided us to represent bone as an interpenetrating composite material. Good agreement was found between the theory and experiments for the elastic moduli of the untreated, deproteinized, and demineralized trabecular bone. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. The behavior of adaptive bone-remodeling simulation models

    NARCIS (Netherlands)

    H.H. Weinans (Harrie); R. Huiskes (Rik); H.J. Grootenboer

    1992-01-01

    textabstractThe process of adaptive bone remodeling can be described mathematically and simulated in a computer model, integrated with the finite element method. In the model discussed here, cortical and trabecular bone are described as continuous materials with variable density. The remodeling rule

  4. Bone healing models in rat tibia after different injuries.

    Science.gov (United States)

    Hussar, P; Piirsoo, A; Märtson, A; Toom, A; Haviko, T; Hussar, U

    2001-01-01

    Gradual elaboration of an adequate and efficient multistage method for experimental remodelling of specific wound healing process--bone repair. Comparison of clinical characteristics with the results of microanatomy, histology, electronmicroscopy and computer morphometry. An investigation of posttraumatic bone repair after internal fracture, excision and cortical perforation was carried out on 142 young adult male Wistar rats. The repair was studied in normal and affected animals (exercises, immobilization, isolation of periost) at 1-42 days after operation. The posttraumatic bone callus development and the related soft tissue repair, likewise the continuous remodelling, is an ordinary process of osteohisto- and organogenese. In trained rats the blood supply and bone formation is increased, whereas in immobilized animals it is inhibited and destroyed (osteoporose, pseudoarthrosis). After the injury some characteristics of bone repair histogenese will be became evident (after the perforation the primary endosteal and secondary periosteal ossification, inhibition of endosteal bone repair after the isolation of periost etc.). The posttraumatic bone healing, like embryohistogenese, has similar repair stages in all models of the experiments as well as similar tissue and cell responses (callus formation, its replacement, bone remodelling, etc.). However, the repair process in general (order of chondrous and/or bone callus stages, etc.) is variable and dependent on the mode and degree of injury. The use of bone cortex perforation in wound healing study is more recommendable as compared to internal fracture and excision (possibility of in situ study the periost and callus tissue compartments in bone repair machinery separately).

  5. Antibacterial Membrane with a Bone-Like Structure for Guided Bone Regeneration

    Directory of Open Access Journals (Sweden)

    YuYuan Zhang

    2015-01-01

    Full Text Available An antibacterial membrane with a bone-like structure was developed for guided bone regeneration (GBR by mineralising acellular bovine pericardium (ABP and loading it with the antibiotic minocycline. The bovine pericardium (BP membrane was processed using physical and chemical methods to remove the cellular components and obtain ABP membranes. Then, the ABP membranes were biomimetically mineralised using a calcium phosphate-loaded agarose hydrogel system aided by electrophoresis. Minocycline was adsorbed to the mineralised ABP membrane, and the release profile in vitro was studied. The membranes were characterised through scanning electron microscopy, diffuse reflectance-Fourier transform infrared spectroscopy, and X-ray diffraction. Results showed that the ABP membrane had an asymmetric structure with a layer of densely arranged and irregularly aligned collagen fibrils. Collagen fibrils were calcified with the formation of intrafibrillar and interfibrillar hydroxyapatites similar to the bone structure. Minocycline was incorporated into the mineralised collagen membrane and could be released in vitro. This process endowed the membrane with an antibacterial property. This novel composite membrane offers promising applications in bioactive GBR.

  6. Review of Animal Models of Prostate Cancer Bone Metastasis

    Directory of Open Access Journals (Sweden)

    Jessica K. Simmons

    2014-06-01

    Full Text Available Prostate cancer bone metastases are associated with a poor prognosis and are considered incurable. Insight into the formation and growth of prostate cancer bone metastasis is required for development of new imaging and therapeutic strategies to combat this devastating disease. Animal models are indispensable in investigating cancer pathogenesis and evaluating therapeutics. Multiple animal models of prostate cancer bone metastasis have been developed, but few effectively model prostatic neoplasms and osteoblastic bone metastases as they occur in men. This review discusses the animal models that have been developed to investigate prostate cancer bone metastasis, with a focus on canine models and also includes human xenograft and rodent models. Adult dogs spontaneously develop benign prostatic hyperplasia and prostate cancer with osteoblastic bone metastases. Large animal models, such as dogs, are needed to develop new molecular imaging tools and effective focal intraprostatic therapy. None of the available models fully reflect the metastatic disease seen in men, although the various models have provided important insight into the metastatic process. As additional models are developed and knowledge from the different models is combined, the molecular mechanisms of prostate cancer bone metastasis can be deciphered and targeted for development of novel therapies and molecular diagnostic imaging.

  7. 3D-Printed Bioactive Ca3SiO5Bone Cement Scaffolds with Nano Surface Structure for Bone Regeneration.

    Science.gov (United States)

    Yang, Chen; Wang, Xiaoya; Ma, Bing; Zhu, Haibo; Huan, Zhiguang; Ma, Nan; Wu, Chengtie; Chang, Jiang

    2017-02-22

    Silicate bioactive materials have been widely studied for bone regeneration because of their eminent physicochemical properties and outstanding osteogenic bioactivity, and different methods have been developed to prepare porous silicate bioactive ceramics scaffolds for bone-tissue engineering applications. Among all of these methods, the 3D-printing technique is obviously the most efficient way to control the porous structure. However, 3D-printed bioceramic porous scaffolds need high-temperature sintering, which will cause volume shrinkage and reduce the controllability of the pore structure accuracy. Unlike silicate bioceramic, bioactive silicate cements such as tricalcium silicate (Ca 3 SiO 5 and C 3 S) can be self-set in water to obtain high mechanical strength under mild conditions. Another advantage of using C 3 S to prepare 3D scaffolds is the possibility of simultaneous drug loading. Herein, we, for the first time, demonstrated successful preparation of uniform 3D-printed C 3 S bone cement scaffolds with controllable 3D structure at room temperature. The scaffolds were loaded with two model drugs and showed a loading location controllable drug-release profile. In addition, we developed a surface modification process to create controllable nanotopography on the surface of pore wall of the scaffolds, which showed activity to enhance rat bone-marrow stem cells (rBMSCs) attachment, spreading, and ALP activities. The in vivo experiments revealed that the 3D-printed C 3 S bone cement scaffolds with nanoneedle-structured surfaces significantly improved bone regeneration, as compared to pure C 3 S bone cement scaffolds, suggesting that 3D-printed C 3 S bone cement scaffolds with controllable nanotopography surface are bioactive implantable biomaterials for bone repair.

  8. Bone morphogenetic proteins: from structure to clinical use

    Directory of Open Access Journals (Sweden)

    Granjeiro J.M.

    2005-01-01

    Full Text Available Bone morphogenetic proteins (BMPs are multi-functional growth factors belonging to the transforming growth factor ß superfamily. Family members are expressed during limb development, endochondral ossification, early fracture, and cartilage repair. The activity of BMPs was first identified in the 1960s but the proteins responsible for bone induction were unknown until the purification and cloning of human BMPs in the 1980s. To date, about 15 BMP family members have been identified and characterized. The signal triggered by BMPs is transduced through serine/threonine kinase receptors, type I and II subtypes. Three type I receptors have been shown to bind BMP ligands, namely: type IA and IB BMP receptors and type IA activin receptors. BMPs seem to be involved in the regulation of cell proliferation, survival, differentiation and apoptosis, but their hallmark is their ability to induce bone, cartilage, ligament, and tendon formation at both heterotopic and orthotopic sites. This suggests that, in the future, they may play a major role in the treatment of bone diseases. Several animal studies have illustrated the potential of BMPs to enhance spinal fusion, repair critical-size defects, accelerate union, and heal articular cartilage lesions. Difficulties in producing and purifying BMPs from bone tissue have prompted the attempts made by several laboratories, including ours, to express these proteins in the recombinant form in heterologous systems. This review focuses on BMP structure, molecular mechanisms of action and significance and potential applications in medical, dental and veterinary practice for the treatment of cartilage and bone-related diseases.

  9. Regularized Structural Equation Modeling

    Science.gov (United States)

    Jacobucci, Ross; Grimm, Kevin J.; McArdle, John J.

    2016-01-01

    A new method is proposed that extends the use of regularization in both lasso and ridge regression to structural equation models. The method is termed regularized structural equation modeling (RegSEM). RegSEM penalizes specific parameters in structural equation models, with the goal of creating easier to understand and simpler models. Although regularization has gained wide adoption in regression, very little has transferred to models with latent variables. By adding penalties to specific parameters in a structural equation model, researchers have a high level of flexibility in reducing model complexity, overcoming poor fitting models, and the creation of models that are more likely to generalize to new samples. The proposed method was evaluated through a simulation study, two illustrative examples involving a measurement model, and one empirical example involving the structural part of the model to demonstrate RegSEM’s utility. PMID:27398019

  10. New predictive model for monitoring bone remodeling

    Czech Academy of Sciences Publication Activity Database

    Bougherara, H.; Klika, Václav; Maršík, František; Mařík, I.; Yahia, L.H.

    95A, č. 1 (2010), s. 9-24 ISSN 1549-3296 R&D Projects: GA ČR GA106/03/1073; GA ČR(CZ) GA106/03/0958 Institutional research plan: CEZ:AV0Z20760514 Keywords : bone remodeling * open system thermodynamics * bone biochemistry Subject RIV: BJ - Thermodynamics Impact factor: 3.044, year: 2010

  11. Defective cancellous bone structure and abnormal response to PTH in cortical bone of mice lacking Cx43 cytoplasmic C-terminus domain

    Science.gov (United States)

    Pacheco-Costa, Rafael; Davis, Hannah M.; Sorenson, Chad; Hon, Mary C.; Hassan, Iraj; Reginato, Rejane D.; Allen, Matthew R.; Bellido, Teresita; Plotkin, Lilian I.

    2015-01-01

    Connexin43 (Cx43) forms gap junction channels and hemichannels that allow the communication among osteocytes, osteoblasts, and osteoclasts. Cx43 carboxy-terminal (CT) domain regulates channel opening and intracellular signaling by acting as a scaffold for structural and signaling proteins. To determine the role of Cx43 CT domain in bone, mice in which one allele of full length Cx43 was replaced by a mutant lacking the CT domain (Cx43ΔCT/fl) were studied. Cx43ΔCT/fl mice exhibit lower cancellous bone volume but higher cortical thickness than Cx43fl/fl controls, indicating that the CT domain is involved in normal cancellous bone gain but opposes cortical bone acquisition. Further, Cx43ΔCT is able to exert the functions of full length osteocytic Cx43 on cortical bone geometry and mechanical properties, demonstrating that domains other than the CT are responsible for Cx43 function in cortical bone. In addition, parathyroid hormone (PTH) failed to increase endocortical bone formation or energy to failure, a mechanical property that indicates resistance to fracture, in cortical bone in Cx43ΔCT mice with or without osteocytic full length Cx43. On the other hand, bone mass and bone formation markers were increased by the hormone in all mouse models, regardless of whether full length or Cx43ΔCT were or not expressed. We conclude that Cx43 CT domain is involved in proper bone acquisition; and that Cx43 expression in osteocytes is dispensable for some but not all PTH anabolic actions. PMID:26409319

  12. High doses of bone morphogenetic protein 2 induce structurally abnormal bone and inflammation in vivo.

    Science.gov (United States)

    Zara, Janette N; Siu, Ronald K; Zhang, Xinli; Shen, Jia; Ngo, Richard; Lee, Min; Li, Weiming; Chiang, Michael; Chung, Jonguk; Kwak, Jinny; Wu, Benjamin M; Ting, Kang; Soo, Chia

    2011-05-01

    The major Food and Drug Association-approved osteoinductive factors in wide clinical use are bone morphogenetic proteins (BMPs). Although BMPs can promote robust bone formation, they also induce adverse clinical effects, including cyst-like bone formation and significant soft tissue swelling. In this study, we evaluated multiple BMP2 doses in a rat femoral segmental defect model and in a minimally traumatic rat femoral onlay model to determine its dose-dependent effects. Results of our femoral segmental defect model established a low BMP2 concentration range (5 and 10 μg/mL, total dose 0.375 and 0.75 μg in 75 μg total volume) unable to induce defect fusion, a mid-range BMP2 concentration range able to fuse the defect without adverse effects (30 μg/mL, total dose 2.25 μg in 75 μg total volume), and a high BMP2 concentration range (150, 300, and 600 μg/mL, total dose 11.25, 22.5, and 45 μg in 75 μg total volume) able to fuse the defect, but with formation of cyst-like bony shells filled with histologically confirmed adipose tissue. In addition, compared to control, 4 mg/mL BMP2 also induced significant tissue inflammatory infiltrates and exudates in the femoral onlay model that was accompanied by increased numbers of osteoclast-like cells at 3, 7, and 14 days. Overall, we consistently reproduced BMP2 side effects of cyst-like bone and soft tissue swelling using high BMP2 concentration approaching the typical human 1500 μg/mL.

  13. Handling of the bone long pseudoarthrosis with autologo structural bone graft in failure osteosynthesis

    International Nuclear Information System (INIS)

    Satizabal Azuero, Carlos; Calderon Uribe, Oscar; Alban P, Paulo Antonio; Gamba Sanchez, Cesar Enrique

    2003-01-01

    We find in the literature that the usual way to treat pseudoarthrosis always includes the removal of the material used to stabilize the fractures, with bring along high hospital and social costs for the patient and the family. The treatment we purpose is the appliance of an autologo structural iliac bone graft, trapezoid form, throughout a minimal incision into the lesion. We treated 12 patients that included 14 long bones in a two year period, age range of 23,2 y 12 (86%) patients with femur pseudoarthrosis, 1 (7%) with tibia y 1 (7%) humerus. we obtained 100% consolidation at 5 months after surgery. no complications reported from the patients, and an important reduce in hospital and social costs

  14. Effect of trabecular bone loss on cortical strain rate during impact in an in vitro model of avian femur

    Directory of Open Access Journals (Sweden)

    Gefen Amit

    2006-07-01

    Full Text Available Abstract Background Osteoporotic hip fractures occur due to loss of cortical and trabecular bone mass and consequent degradation in whole bone strength. The direct cause of most fractures is a fall, and hence, characterizing the mechanical behavior of a whole osteopenic bone under impact is important. However, very little is known about the mechanical interactions between cortical and trabecular bone during impact, and it is specifically unclear to what extent epiphyseal trabecular bone contributes to impact resistance of whole bones. We hypothesized that trabecular bone serves as a structural support to the cortex during impact, and hence, loss of a critical mass of trabecular bone reduces internal constraining of the cortex, and, thereby, decreases the impact tolerance of the whole bone. Methods To test this hypothesis, we conducted cortical strain rate measurements in adult chicken's proximal femora subjected to a Charpy impact test, after removing different trabecular bone core masses to simulate different osteopenic severities. Results We found that removal of core trabecular bone decreased by ~10-fold the cortical strain rate at the side opposite to impact (p Conclusion We conclude that in our in vitro avian model, loss of over 10% of core trabecular bone substantially altered the deformation response of whole bone to impact, which supports the above hypothesis and indicates that integrity of trabecular bone is critical for resisting impact loads.

  15. The Ovariectomized Rat as a Model for Studying Alveolar Bone Loss in Postmenopausal Women

    Directory of Open Access Journals (Sweden)

    Bryan D. Johnston

    2015-01-01

    Full Text Available In postmenopausal women, reduced bone mineral density at the hip and spine is associated with an increased risk of tooth loss, possibly due to a loss of alveolar bone. In turn, having fewer natural teeth may lead to compromised food choices resulting in a poor diet that can contribute to chronic disease risk. The tight link between alveolar bone preservation, tooth retention, better nutritional status, and reduced risk of developing a chronic disease begins with the mitigation of postmenopausal bone loss. The ovariectomized rat, a widely used preclinical model for studying postmenopausal bone loss that mimics deterioration of bone tissue in the hip and spine, can also be used to study mineral and structural changes in alveolar bone to develop drug and/or dietary strategies aimed at tooth retention. This review discusses key findings from studies investigating mandible health and alveolar bone in the ovariectomized rat model. Considerations to maximize the benefits of this model are also included. These include the measurement techniques used, the age at ovariectomy, the duration that a rat is studied after ovariectomy and habitual diet consumed.

  16. Etelcalcetide (AMG 416), a peptide agonist of the calcium-sensing receptor, preserved cortical bone structure and bone strength in subtotal nephrectomized rats with established secondary hyperparathyroidism.

    Science.gov (United States)

    Li, Xiaodong; Yu, Longchuan; Asuncion, Frank; Grisanti, Mario; Alexander, Shawn; Hensley, Kelly; Han, Chun-Ya; Niu, Qing-Tian; Dwyer, Denise; Villasenor, Kelly; Stolina, Marina; Dean, Charles; Ominsky, Michael S; Ke, Hua Zhu; Tomlinson, James E; Richards, William G

    2017-12-01

    Sustained elevation of parathyroid hormone (PTH) is catabolic to cortical bone, as evidenced by deterioration in bone structure (cortical porosity), and is a major factor for increased fracture risk in chronic kidney disease (CKD). Etelcalcetide (AMG 416), a novel peptide agonist of the calcium-sensing receptor, reduces PTH levels in subtotal nephrectomized (Nx) rats and in hemodialysis patients with secondary hyperparathyroidism (SHPT) in clinical studies; however, effects of etelcalcetide on bone have not been determined. In a rat model of established SHPT with renal osteodystrophy, etelcalcetide or vehicle was administered by subcutaneous (s.c.) injection to subtotal Nx rats with elevated PTH (>750pg/mL) once per day for 6weeks. Sham-operated rats receiving vehicle (s.c.) served as non-SHPT controls. Prior to treatment, significant increases in serum creatinine (2-fold), blood urea nitrogen (BUN, 3-fold), PTH (5-fold), fibroblast growth factor-23 (FGF23; 13-fold) and osteocalcin (12-fold) were observed in SHPT rats compared to non-SHPT controls. Elevations in serum creatinine and BUN were unaffected by treatment with vehicle or etelcalcetide. In contrast, etelcalcetide significantly decreased PTH, FGF23 and osteocalcin, whereas vehicle treatment did not. Cortical bone porosity increased and bone strength decreased in vehicle-treated SHPT rats compared to non-SHPT controls. Cortical bone structure improved and energy to failure was significantly greater in SHPT rats treated with etelcalcetide compared to vehicle. Mineralization lag time and marrow fibrosis were significantly reduced by etelcalcetide. In conclusion, etelcalcetide reduced bone turnover, attenuated mineralization defect and marrow fibrosis, and preserved cortical bone structure and bone strength by lowering PTH in subtotal Nx rats with established SHPT. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  17. Animal models for implant biomaterial research in bone: A review

    Directory of Open Access Journals (Sweden)

    A I Pearce

    2007-03-01

    Full Text Available Development of an optimal interface between bone and orthopaedic and dental implants has taken place for many years. In order to determine whether a newly developed implant material conforms to the requirements of biocompatibility, mechanical stability and safety, it must undergo rigorous testing both in vitro and in vivo. Results from in vitro studies can be difficult to extrapolate to the in vivo situation. For this reason the use of animal models is often an essential step in the testing of orthopaedic and dental implants prior to clinical use in humans. This review discusses some of the more commonly available and frequently used animal models such as the dog, sheep, goat, pig and rabbit models for the evaluation of bone-implant interactions. Factors for consideration when choosing an animal model and implant design are discussed. Various bone specific features are discussed including the usage of the species, bone macrostructure and microstructure and bone composition and remodelling, with emphasis being placed on the similarity between the animal model and the human clinical situation. While the rabbit was the most commonly used of the species discussed in this review, it is clear that this species showed the least similarities to human bone. There were only minor differences in bone composition between the various species and humans. The pig demonstrated a good likeness with human bone however difficulties may be encountered in relation to their size and ease of handling. In this respect the dog and sheep/goat show more promise as animal models for the testing of bone implant materials. While no species fulfils all of the requirements of an ideal model, an understanding of the differences in bone architecture and remodelling between the species is likely to assist in the selection of a suitable species for a defined research question.

  18. Vascularized bone grafting in a canine carpal avascular necrosis model

    NARCIS (Netherlands)

    Willems, Wouter F.; Alberton, Gregory M.; Bishop, Allen T.; Kremer, Thomas

    2011-01-01

    Limited experimental research has been performed on the treatment of avascular necrosis (AVN) by vascularized bone grafting. A new model simulating carpal AVN was created to investigate surgical revascularization of necrotic bone. In seven mongrel dogs, AVN was induced by removal of the radial

  19. Patient-specific three-dimensional composite bone models for teaching and operation planning.

    Science.gov (United States)

    Matthews, Felix; Messmer, Peter; Raikov, Vladislav; Wanner, Guido A; Jacob, Augustinus L; Regazzoni, Pietro; Egli, Adrian

    2009-10-01

    Orthopedic trauma care relies on two-dimensional radiograms both before and during the operation. Understanding the three-dimensional nature of complex fractures on plain radiograms is challenging. Modern fluoroscopes can acquire three-dimensional volume datasets even during an operation, but the device limitations constrain the acquired volume to a cube of only 12-cm edge. However, viewing the surrounding intact structures is important to comprehend the fracture in its context. We suggest merging a fluoroscope's volume scan into a generic bone model to form a composite full-length 3D bone model. Materials consisted of one cadaver bone and 20 three-dimensional surface models of human femora. Radiograms and computed tomography scans were taken before and after applying a controlled fracture to the bone. A 3D scan of the fracture was acquired using a mobile fluoroscope (Siemens Siremobil). The fracture was fitted into the generic bone models by rigid registration using a modified least-squares algorithm. Registration precision was determined and a clinical appraisal of the composite models obtained. Twenty composite bone models were generated. Average registration precision was 2.0 mm (range 1.6 to 2.6). Average processing time on a laptop computer was 35 s (range 20 to 55). Comparing synthesized radiograms with the actual radiograms of the fractured bone yielded clinically satisfactory results. A three-dimensional full-length representation of a fractured bone can reliably be synthesized from a short scan of the patient's fracture and a generic bone model. This patient-specific model can subsequently be used for teaching, surgical operation planning, and intraoperative visualization purposes.

  20. Tough and strong porous bioactive glass-PLA composites for structural bone repair.

    Science.gov (United States)

    Xiao, Wei; Zaeem, Mohsen Asle; Li, Guangda; Bal, B Sonny; Rahaman, Mohamed N

    2017-08-01

    Bioactive glass scaffolds have been used to heal small contained bone defects but their application to repairing structural bone is limited by concerns about their mechanical reliability. In the present study, the addition of an adherent polymer layer to the external surface of strong porous bioactive glass (13-93) scaffolds was investigated to improve their toughness. Finite element modeling (FEM) of the flexural mechanical response of beams composed of a porous glass and an adherent polymer layer predicted a reduction in the tensile stress in the glass with increasing thickness and elastic modulus of the polymer layer. Mechanical testing of composites with structures similar to the models, formed from 13-93 glass and polylactic acid (PLA), showed trends predicted by the FEM simulations but the observed effects were considerably more dramatic. A PLA layer of thickness -400 µm, equal to -12.5% of the scaffold thickness, increased the load-bearing capacity of the scaffold in four-point bending by ~50%. The work of fracture increased by more than 10,000%, resulting in a non-brittle mechanical response. These bioactive glass-PLA composites, combining bioactivity, high strength, high work of fracture and an internal architecture shown to be conducive to bone infiltration, could provide optimal implants for healing structural bone defects.

  1. Modeling the effects of inflammation in bone fracture healing

    Science.gov (United States)

    Kojouharov, H. V.; Trejo, I.; Chen-Charpentier, B. M.

    2017-10-01

    A new mathematical model is presented to study the early inflammatory effects in bone healing. It consists of a system of nonlinear ordinary differential equations that represents the interactions among macrophages, mesenchymal stem cells, and osteoblasts. A qualitative analysis of the model is performed to determine the equilibria and their corresponding stability properties. A set of numerical simulations is performed to support the theoretical results. The model is also used to numerically monitor the evolution of a broken bone for different types of fractures and to explore possible treatments to accelerate bone healing by administrating anti-inflammatory drugs.

  2. Marked changes in iliac crest bone structure in postmenopausal osteoporotic patients without any signs of disturbed bone remodeling or balance.

    Science.gov (United States)

    Steiniche, T; Christiansen, P; Vesterby, A; Hasling, C; Ullerup, R; Mosekilde, L; Melsen, F

    1994-01-01

    Successful iliac crest bone biopsies were obtained from 63 women with postmenopausal vertebral crush fracture osteoporosis. Structural and static histomorphometric parameters were compared with 25 age-matched normal females, who had suffered an unexpected and sudden death. The control group for dynamic parameters comprised 13 younger normal females. Marked structural changes were observed in the osteoporotic patients in cortical as well as cancellous bone. Cortical width, trabecular volume, trabecular bone surface density and trabecular number were all reduced, whereas trabecular separation and star volume were increased. On the other hand trabecular thickness was normal in the patients. These structural changes in cancellous bone indicate that extensive perforations of trabecular plates have occurred or that whole trabecular elements have been removed. The remodeling cycles of cancellous bone surface and the frequency by which they were repeated (activation frequency) did not differ significantly between osteoporotic patients and normal younger women. The bone balance per remodeling cycle in osteoporotic patients and controls was not significantly different. No subset of individuals in the group of osteoporotic patients could be identified regarding extent of resorptive and formative surfaces, bone formation rate or activation frequency. In the present osteoporotic patients nothing in the ongoing remodeling process could explain the marked changes in bone structure. The pathophysiological changes leading to osteoporosis may therefore occur earlier in life, maybe long before the manifestation of the disease.

  3. Trabecular bone structural parameters evaluated using dental cone-beam computed tomography: cellular synthetic bones.

    Science.gov (United States)

    Ho, Jung-Ting; Wu, Jay; Huang, Heng-Li; Chen, Michael Y c; Fuh, Lih-Jyh; Hsu, Jui-Ting

    2013-11-09

    This study compared the adequacy of dental cone beam computed tomography (CBCT) and micro computed tomography (micro-CT) in evaluating the structural parameters of trabecular bones. The cellular synthetic bones in 4 density groups (Groups 1-4: 0.12, 0.16, 0.20, and 0.32 g/cm3) were used in this study. Each group comprised 8 experimental specimens that were approximately 1 cm3. Dental CBCT and micro-CT scans were conducted on each specimen to obtain independent measurements of the following 4 trabecular bone structural parameters: bone volume fraction (BV/TV), specific bone surface (BS/BV), trabecular thickness (Tb.Th.), and trabecular separation (Tb.Sp.). Wilcoxon signed ranks tests were used to compare the measurement variations between the dental CBCT and micro-CT scans. A Spearman analysis was conducted to calculate the correlation coefficients (r) of the dental CBCT and micro-CT measurements. Of the 4 groups, the BV/TV and Tb.Th. measured using dental CBCT were larger compared with those measured using micro-CT. By contrast, the BS/BV measured using dental CBCT was significantly less compared with those measured using micro-CT. Furthermore, in the low-density groups (Groups 1 and 2), the Tb.Sp. measured using dental CBCT was smaller compared with those measured using micro-CT. However, the Tb.Sp. measured using dental CBCT was slightly larger in the high-density groups (Groups 3 and 4) than it was in the low density groups. The correlation coefficients between the BV/TV, BS/BV, Tb.Th., and Tb.Sp. values measured using dental CBCT and micro-CT were 0.9296 (p < .001), 0.8061 (p < .001), 0.9390 (p < .001), and 0.9583 (p < .001), respectively. Although the dental CBCT and micro-CT approaches exhibited high correlations, the absolute values of BV/TV, BS/BV, Tb.Th., Tb.Sp. differed significantly between these measurements. Additional studies must be conducted to evaluate using dental CBCT in clinical practice.

  4. Modeling Fluid Structure Interaction

    National Research Council Canada - National Science Library

    Benaroya, Haym

    2000-01-01

    The principal goal of this program is on integrating experiments with analytical modeling to develop physics-based reduced-order analytical models of nonlinear fluid-structure interactions in articulated naval platforms...

  5. Non-rigid image registration using bone growth model

    DEFF Research Database (Denmark)

    Bro-Nielsen, Morten; Gramkow, Claus; Kreiborg, Sven

    1997-01-01

    Non-rigid registration has traditionally used physical models like elasticity and fluids. These models are very seldom valid models of the difference between the registered images. This paper presents a non-rigid registration algorithm, which uses a model of bone growth as a model of the change b...

  6. Error analysis: How precise is fused deposition modeling in fabrication of bone models in comparison to the parent bones?

    Directory of Open Access Journals (Sweden)

    M V Reddy

    2018-01-01

    Full Text Available Background: Rapid prototyping (RP is used widely in dental and faciomaxillary surgery with anecdotal uses in orthopedics. The purview of RP in orthopedics is vast. However, there is no error analysis reported in the literature on bone models generated using office-based RP. This study evaluates the accuracy of fused deposition modeling (FDM using standard tessellation language (STL files and errors generated during the fabrication of bone models. Materials and Methods: Nine dry bones were selected and were computed tomography (CT scanned. STL files were procured from the CT scans and three-dimensional (3D models of the bones were printed using our in-house FDM based 3D printer using Acrylonitrile Butadiene Styrene (ABS filament. Measurements were made on the bone and 3D models according to data collection procedures for forensic skeletal material. Statistical analysis was performed to establish interobserver co-relation for measurements on dry bones and the 3D bone models. Statistical analysis was performed using SPSS version 13.0 software to analyze the collected data. Results: The inter-observer reliability was established using intra-class coefficient for both the dry bones and the 3D models. The mean of absolute difference is 0.4 that is very minimal. The 3D models are comparable to the dry bones. Conclusions: STL file dependent FDM using ABS material produces near-anatomical 3D models. The high 3D accuracy hold a promise in the clinical scenario for preoperative planning, mock surgery, and choice of implants and prostheses, especially in complicated acetabular trauma and complex hip surgeries.

  7. Sheep model for osteoporosis: The effects of peripheral hormone therapy on centrally induced systemic bone loss in an osteoporotic sheep model.

    Science.gov (United States)

    Oheim, Ralf; Simon, Maciej J K; Steiner, Malte; Vettorazzi, Eik; Barvencik, Florian; Ignatius, Anita; Amling, Michael; Clarke, Iain J; Pogoda, Pia; Beil, F Timo

    2017-04-01

    Hypothalamic-pituitary disconnection (HPD) leads to low bone turnover followed by bone loss and reduced biomechanical properties in sheep. To investigate the role of peripheral hormones in this centrally induced systemic bone loss model, we planned a hormone replacement experiment. Therefore, estrogen (OHE), thyroxin (OHT) or a combination of both (OHTE) was substituted in ovariectomized HPD sheep, as both hormones are decreased in HPD sheep and are known to have a significant but yet not fully understood impact on bone metabolism. Bone turnover and structural parameters were analyzed in comparison to different control groups - untreated sheep (C), ovariectomized (O) and ovariectomized+HPD sheep (OH). We performed histomorphometric and HR-pQCT analyses nine months after the HPD procedure, as well as biomechanical testing of all ewes studied. In HPD sheep (OH) the low bone turnover led to a significant bone loss. Treatment with thyroxin alone (OHT) mainly increased bone resorption, leading to a further reduction in bone volume. In contrast, the treatment with estrogen alone (OHE) and the combined treatment with estrogen and thyroxin (OHTE) prevented HPD-induced bone loss completely. In conclusion, peripheral hormone substitution was able to prevent HPD-induced low-turnover osteoporosis in sheep. But only the treatment with estrogen alone or in combination with thyroxin was able to completely preserve bone mass and structure. These findings demonstrate the importance of peripheral hormones for a balanced bone remodeling and a physiological bone turnover. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Bone regeneration using a bone morphogenetic protein-2 saturated slow-release gelatin hydrogel sheet: evaluation in a canine orbital floor fracture model.

    Science.gov (United States)

    Asamura, Shinichi; Mochizuki, Yuichi; Yamamoto, Masaya; Tabata, Yasuhiko; Isogai, Noritaka

    2010-04-01

    Bone regeneration methods using bone inductive cytokines show promise, however, due to early diffusion and absorption of single applications of these cytokines, the bone inductive effects are limited. In this study, such a system was applied, using gelatin hydrogel as a carrier to slowly release (bone morphogenetic proteins) BMP-2 over a relatively long period in vivo. By coupling this slow-release system with a biodegradable copolymer, this composite was evaluated by grafting into bone defect sites of a canine orbital floor fracture model. Radio-iodinated BMP-2 incorporated into the gelatin hydrogel carrier and subcutaneously implanted into nude mice showed a similar slow release (approximately, 60% at 3 days and 80% at 14 days) as the radiolabeled hydrogel carrier alone. In contrast, greater than 90% of fluid-injected BMP-2 was lost in the injection site within the first 8 hours. Using a dog model of orbital floor fracture, a complex of BMP-2-saturated gelatin hydrogel and a polylactide-based biodegradable copolymer was implanted into the orbital bone defect. Bone structural analysis, using radiography, histologic examination, and microfocus CT, showed greatly enhanced new bone formation and defect healing at 5 weeks in comparison to implanted biodegradable copolymer directly saturated with the same amount of BMP-2 (no slow-release hydrogel carrier). A trabecular structure resembling that normal bone tissue was restored in the new bone tissue generated by the slow-release constructs. Thus study demonstrates the potential of slow-release BMP-2 for bone healing of difficult defects.

  9. [Bone Cell Biology Assessed by Microscopic Approach. Bone histomorphometry of remodeling, modeling and minimodeling].

    Science.gov (United States)

    Yamamoto, Noriaki; Shimakura, Taketoshi; Takahashi, Hideaki

    2015-10-01

    Bone histomorphometry is defined as a quantitative evaluation of bone remodeling. In bone remodeling, bone resorption and bone formation are coupled with scalloped cement lines. Another mechanism of bone formation is minimodeling which bone formation and resorption are independent. The finding of minimodeling appeared in special condition with metabolic bone disease or anabolic agents. We need further study for minimodeling feature and mechanism.

  10. Strong similarities in the creep and damage behaviour of a synthetic bone model compared to human trabecular bone under compressive cyclic loading.

    Science.gov (United States)

    Purcell, Philip; Tiernan, Stephen; McEvoy, Fiona; Morris, Seamus

    2015-08-01

    Understanding the failure modes which instigate vertebral collapse requires the determination of trabecular bone fatigue properties, since many of these fractures are observed clinically without any preceding overload event. Alternatives to biological bone tissue for in-vitro fatigue studies are available in the form of commercially available open cell polyurethane foams. These test surrogates offer particular advantages compared to biological tissue such as a controllable architecture and greater uniformity. The present study provides a critical evaluation of these models as a surrogate to human trabecular bone tissue for the study of vertebral augmentation treatments such as balloon kyphoplasty. The results of this study show that while statistically significant differences were observed for the damage response of the two materials, both share a similar three phase modulus reduction over their life span with complete failure rapidly ensuing at damage levels above 30%. No significant differences were observed for creep accumulation properties, with greater than 50% of creep strains being accumulated during the first quarter of the life span for both materials. A significant power law relationship was identified between damage accumulation rate and cycles to failure for the synthetic bone model along with comparable microarchitectural features and a hierarchical composite structure consistent with biological bone. These findings illustrate that synthetic bone models offer potential as a surrogate for trabecular bone to an extent that warrants a full validation study to define boundaries of use which compliment traditional tests using biological bone. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. Bone compaction enhances implant fixation in a canine gap model

    DEFF Research Database (Denmark)

    Kold, Søren Vedding; Rahbek, Ole; Toft, Marianne

    2005-01-01

    A new bone preparation technique, compaction, has increased fixation of implants inserted with exact-fit or press-fit to bone. Furthermore, a demonstrated spring-back effect of compacted bone might be of potential value in reducing the initial gaps that often exist between clinical inserted...... implants and bone. However, it is unknown whether the compression and breakage of trabeculae during the compaction procedure results in impaired gap-healing of compacted bone. Therefore, we compared compaction with conventional drilling in a canine gap model. Grit-blasted titanium implants (diameter 6 mm......) were bilaterally inserted into cavities initially expanded to 8 mm diameters in the proximal humeri. Each dog served as its own control; thus, one humerus had the implant cavity prepared with compaction, the other with drilling. Eight dogs were euthanized after 2 weeks, and 7 dogs after 4 weeks. Humeri...

  12. Modeling of Stiffness and Strength of Bone at Nanoscale.

    Science.gov (United States)

    Abueidda, Diab W; Sabet, Fereshteh A; Jasiuk, Iwona M

    2017-05-01

    Two distinct geometrical models of bone at the nanoscale (collagen fibril and mineral platelets) are analyzed computationally. In the first model (model I), minerals are periodically distributed in a staggered manner in a collagen matrix while in the second model (model II), minerals form continuous layers outside the collagen fibril. Elastic modulus and strength of bone at the nanoscale, represented by these two models under longitudinal tensile loading, are studied using a finite element (FE) software abaqus. The analysis employs a traction-separation law (cohesive surface modeling) at various interfaces in the models to account for interfacial delaminations. Plane stress, plane strain, and axisymmetric versions of the two models are considered. Model II is found to have a higher stiffness than model I for all cases. For strength, the two models alternate the superiority of performance depending on the inputs and assumptions used. For model II, the axisymmetric case gives higher results than the plane stress and plane strain cases while an opposite trend is observed for model I. For axisymmetric case, model II shows greater strength and stiffness compared to model I. The collagen-mineral arrangement of bone at nanoscale forms a basic building block of bone. Thus, knowledge of its mechanical properties is of high scientific and clinical interests.

  13. Porous Alpha-Tricalcium Phosphate with Immobilized Basic Fibroblast Growth Factor Enhances Bone Regeneration in a Canine Mandibular Bone Defect Model

    Directory of Open Access Journals (Sweden)

    Nobuhiro Kobayashi

    2016-10-01

    Full Text Available The effect of porous alpha-tricalcium phosphate (α-TCP with immobilized basic fibroblast growth factor (bFGF on bone regeneration was evaluated in a canine mandibular bone defect model. Identical bone defects were made in the canine mandible; six defects in each animal were filled with porous α-TCP with bFGF bound via heparin (bFGF group, whereas the other was filled with unmodified porous α-TCP (control group. Micro-computed tomography and histological evaluation were performed two, four and eight weeks after implantation. The bone mineral density of the bFGF group was higher than that of the control group at each time point (p < 0.05, and the bone mineral content of the bFGF group was higher than that of the control group at four and eight weeks (p < 0.05. Histological evaluation two weeks after implantation revealed that the porous α-TCP had degraded and bone had formed on the surface of α-TCP particles in the bFGF group. At eight weeks, continuous cortical bone with a Haversian structure covered the top of bone defects in the bFGF group. These findings demonstrate that porous α-TCP with immobilized bFGF can promote bone regeneration.

  14. Creation of a 3D printed temporal bone model from clinical CT data.

    Science.gov (United States)

    Cohen, Joss; Reyes, Samuel A

    2015-01-01

    Generate and describe the process of creating a 3D printed, rapid prototype temporal bone model from clinical quality CT images. We describe a technique to create an accurate, alterable, and reproducible rapid prototype temporal bone model using freely available software to segment clinical CT data and generate three different 3D models composed of ABS plastic. Each model was evaluated based on the appearance and size of anatomical structures and response to surgical drilling. Mastoid air cells had retained scaffolding material in the initial versions. This required modifying the model to allow drainage of the scaffolding material. External auditory canal dimensions were similar to those measured from the clinical data. Malleus, incus, oval window, round window, promontory, horizontal semicircular canal, and mastoid segment of the facial nerve canal were identified in all models. The stapes was only partially formed in two models and absent in the third. Qualitative feel of the ABS plastic was softer than bone. The pate produced by drilling was similar to bone dust when appropriate irrigation was used. We present a rapid prototype temporal bone model made based on clinical CT data using 3D printing technology. The model can be made quickly and inexpensively enough to have potential applications for educational training. Copyright © 2015 Elsevier Inc. All rights reserved.

  15. Design of complex bone internal structure using topology optimization with perimeter control.

    Science.gov (United States)

    Park, Jaejong; Sutradhar, Alok; Shah, Jami J; Paulino, Glaucio H

    2018-03-01

    Large facial bone loss usually requires patient-specific bone implants to restore the structural integrity and functionality that also affects the appearance of each patient. Titanium alloys (e.g., Ti-6Al-4V) are typically used in the interfacial porous coatings between the implant and the surrounding bone to promote stability. There exists a property mismatch between the two that in general leads to complications such as stress-shielding. This biomechanical discrepancy is a hurdle in the design of bone replacements. To alleviate the mismatch, the internal structure of the bone replacements should match that of the bone. Topology optimization has proven to be a good technique for designing bone replacements. However, the complex internal structure of the bone is difficult to mimic using conventional topology optimization methods without additional restrictions. In this work, the complex bone internal structure is recovered using a perimeter control based topology optimization approach. By restricting the solution space by means of the perimeter, the intricate design complexity of bones can be achieved. Three different bone regions with well-known physiological loadings are selected to illustrate the method. Additionally, we found that the target perimeter value and the pattern of the initial distribution play a vital role in obtaining the natural curvatures in the bone internal structures as well as avoiding excessive island patterns. Copyright © 2018 Elsevier Ltd. All rights reserved.

  16. Modelling collagen diseases: STRUCTURAL BIOLOGY

    OpenAIRE

    Brodsky, Barbara; Baum, Jean

    2008-01-01

    Mutations in collagen lead to hereditary disorders such as brittle-bone disease. Peptide models for aberrant collagens are beginning to clarify how these amino-acid replacements lead to clinical problems.

  17. Vibration acceleration promotes bone formation in rodent models.

    Directory of Open Access Journals (Sweden)

    Ryohei Uchida

    Full Text Available All living tissues and cells on Earth are subject to gravitational acceleration, but no reports have verified whether acceleration mode influences bone formation and healing. Therefore, this study was to compare the effects of two acceleration modes, vibration and constant (centrifugal accelerations, on bone formation and healing in the trunk using BMP 2-induced ectopic bone formation (EBF mouse model and a rib fracture healing (RFH rat model. Additionally, we tried to verify the difference in mechanism of effect on bone formation by accelerations between these two models. Three groups (low- and high-magnitude vibration and control-VA groups were evaluated in the vibration acceleration study, and two groups (centrifuge acceleration and control-CA groups were used in the constant acceleration study. In each model, the intervention was applied for ten minutes per day from three days after surgery for eleven days (EBF model or nine days (RFH model. All animals were sacrificed the day after the intervention ended. In the EBF model, ectopic bone was evaluated by macroscopic and histological observations, wet weight, radiography and microfocus computed tomography (micro-CT. In the RFH model, whole fracture-repaired ribs were excised with removal of soft tissue, and evaluated radiologically and histologically. Ectopic bones in the low-magnitude group (EBF model had significantly greater wet weight and were significantly larger (macroscopically and radiographically than those in the other two groups, whereas the size and wet weight of ectopic bones in the centrifuge acceleration group showed no significant difference compared those in control-CA group. All ectopic bones showed calcified trabeculae and maturated bone marrow. Micro-CT showed that bone volume (BV in the low-magnitude group of EBF model was significantly higher than those in the other two groups (3.1±1.2mm3 v.s. 1.8±1.2mm3 in high-magnitude group and 1.3±0.9mm3 in control-VA group, but

  18. Segmenting Bone Parts for Bone Age Assessment using Point Distribution Model and Contour Modelling

    Science.gov (United States)

    Kaur, Amandeep; Singh Mann, Kulwinder, Dr.

    2018-01-01

    Bone age assessment (BAA) is a task performed on radiographs by the pediatricians in hospitals to predict the final adult height, to diagnose growth disorders by monitoring skeletal development. For building an automatic bone age assessment system the step in routine is to do image pre-processing of the bone X-rays so that features row can be constructed. In this research paper, an enhanced point distribution algorithm using contours has been implemented for segmenting bone parts as per well-established procedure of bone age assessment that would be helpful in building feature row and later on; it would be helpful in construction of automatic bone age assessment system. Implementation of the segmentation algorithm shows high degree of accuracy in terms of recall and precision in segmenting bone parts from left hand X-Rays.

  19. Characterization of augmented bone structures with μ-computed tomography and Raman spectroscopy

    International Nuclear Information System (INIS)

    Charwat-Pessler, Johann; Entacher, Karl; Petutschnigg, Alexander; Musso, Maurizio; Plank, Bernhard; Schuller- Götzburg, Peter; Tangl, Stefan

    2013-01-01

    Full text: In the recent past bone graft substitutes are increasingly used in the medical field in order replace missing bone or promote new bone formation. Computed tomography methods provide density information of biomaterials, however, the question how far information on the chemical structure is accessible has not been intensively investigated yet. In the present study a bone sample consisting of autogenous bone derived cells and bovine bone mineral was investigated by computed microtomography imaging and by Raman spectroscopic imaging, and comparing the image data by means of regression analysis and digital image processing methods. (author)

  20. Sensitivity Analysis of the Bone Fracture Risk Model

    Science.gov (United States)

    Lewandowski, Beth; Myers, Jerry; Sibonga, Jean Diane

    2017-01-01

    Introduction: The probability of bone fracture during and after spaceflight is quantified to aid in mission planning, to determine required astronaut fitness standards and training requirements and to inform countermeasure research and design. Probability is quantified with a probabilistic modeling approach where distributions of model parameter values, instead of single deterministic values, capture the parameter variability within the astronaut population and fracture predictions are probability distributions with a mean value and an associated uncertainty. Because of this uncertainty, the model in its current state cannot discern an effect of countermeasures on fracture probability, for example between use and non-use of bisphosphonates or between spaceflight exercise performed with the Advanced Resistive Exercise Device (ARED) or on devices prior to installation of ARED on the International Space Station. This is thought to be due to the inability to measure key contributors to bone strength, for example, geometry and volumetric distributions of bone mass, with areal bone mineral density (BMD) measurement techniques. To further the applicability of model, we performed a parameter sensitivity study aimed at identifying those parameter uncertainties that most effect the model forecasts in order to determine what areas of the model needed enhancements for reducing uncertainty. Methods: The bone fracture risk model (BFxRM), originally published in (Nelson et al) is a probabilistic model that can assess the risk of astronaut bone fracture. This is accomplished by utilizing biomechanical models to assess the applied loads; utilizing models of spaceflight BMD loss in at-risk skeletal locations; quantifying bone strength through a relationship between areal BMD and bone failure load; and relating fracture risk index (FRI), the ratio of applied load to bone strength, to fracture probability. There are many factors associated with these calculations including

  1. Deletion of Adseverin in Osteoclasts Affects Cell Structure But Not Bone Metabolism

    NARCIS (Netherlands)

    Cao, Yixuan; Wang, Yongqiang; Sprangers, Sara; Picavet, Daisy I.; Glogauer, Michael; McCulloch, Christopher A.; Everts, Vincent

    2017-01-01

    Adseverin is an actin-severing/capping protein that may contribute to osteoclast differentiation in vitro but its role in bone remodeling of healthy animals is not defined. We analyzed bone and osteoclast structure in adseverin conditional null mice at alveolar and long bone sites. In wild-type and

  2. Integration of a Finite Element Model with the DAP Bone Remodeling Model to Characterize Bone Response to Skeletal Loading

    Science.gov (United States)

    Werner, Christopher R.; Mulugeta, Lealem; Myers, J. G.; Pennline, J. A.

    2015-01-01

    NASA's Digital Astronaut Project (DAP) has developed a bone remodeling model that has been validated for predicting volumetric bone mineral density (vBMD) changes of trabecular and cortical bone in the absence of mechanical loading. The model was recently updated to include skeletal loading from exercise and free living activities to maintain healthy bone using a new daily load stimulus (DLS). This new formula was developed based on an extensive review of existing DLS formulas, as discussed in the abstract by Pennline et al. The DLS formula incorporated into the bone remodeling model utilizes strains and stress calculated from finite element model (FEM) of the bone region of interest. The proximal femur was selected for the initial application of the DLS formula, with a specific focus on the femoral neck. METHODS: The FEM was generated from CAD geometry of a femur using de-identified CT data. The femur was meshed using linear tetrahedral elements Figure (1) with higher mesh densities in the femoral neck region, which is the primary region of interest for the initial application of the DLS formula in concert with the DAP bone remodeling model. Nodal loads were applied to the femoral head and the greater trochanter and the base of the femur was held fixed. An L2 norm study was conducted to reduce the length of the femoral shaft without significantly impacting the stresses in the femoral neck. The material properties of the FEM of the proximal femur were separated between cortical and trabecular regions to work with the bone remodeling model. Determining the elements with cortical material properties in the FEM was based off of publicly available CT hip scans [4] that were segmented, cleaned, and overlaid onto the FEM.

  3. Evaluation of a customized artificial osteoporotic bone model of the distal femur.

    Science.gov (United States)

    Wähnert, Dirk; Hoffmeier, Konrad L; Stolarczyk, Yves; Fröber, Rosemarie; Hofmann, Gunther O; Mückley, Thomas

    2011-11-01

    In the development of new implants biomechanical testing is essential. Since human bones vary markedly in density and geometry their suitability for biomechanical testing is limited. In contrast artificial bones are of great uniformity and therefore appropriate for biomechanical testing. However, the applied artificial bones have to be proved as comparable to human bone. An anatomical shaped artificial bone representing the distal human femur was created by foaming polyurethane. To get a bone model with properties of osteoporotic bone a foam density of 150 kg/m3 was used. The biomechanical properties of our artificial bones were evaluated against eight mildly osteoporotic fresh frozen human femora by mechanical testing. At the artificial bones all tested parameters showed a very small variation. In contrast significant correlation between bone mass density and tested parameters was found for the human bones. The artificial bones reached 39% of the compression strength and 41% of the screw pullout force of the human bone. In indentation testing the artificial bones reached 27% (cancellous) and 59% (cortical) respectively of the human bones strength. Regarding Shore hardness artificial bone and human bone showed comparable results for the cortical layer and at the cancellous layer the artificial bone reached 57% of human bones hardness. Our described method for customizing of artificial bones regarding their shape and bone stock quality provides suitable results. In relation to the as mildly osteoporotic classified human bones we assume that the biomechanical properties matching to serve osteoporotic bone.

  4. Empirical angle-dependent Biot and MBA models for acoustic anisotropy in cancellous bone

    International Nuclear Information System (INIS)

    Lee, Kang ll; Hughes, E R; Humphrey, V F; Leighton, T G; Choi, Min Joo

    2007-01-01

    The Biot and the modified Biot-Attenborough (MBA) models have been found useful to understand ultrasonic wave propagation in cancellous bone. However, neither of the models, as previously applied to cancellous bone, allows for the angular dependence of acoustic properties with direction. The present study aims to account for the acoustic anisotropy in cancellous bone, by introducing empirical angle-dependent input parameters, as defined for a highly oriented structure, into the Biot and the MBA models. The anisotropy of the angle-dependent Biot model is attributed to the variation in the elastic moduli of the skeletal frame with respect to the trabecular alignment. The angle-dependent MBA model employs a simple empirical way of using the parametric fit for the fast and the slow wave speeds. The angle-dependent models were used to predict both the fast and slow wave velocities as a function of propagation angle with respect to the trabecular alignment of cancellous bone. The predictions were compared with those of the Schoenberg model for anisotropy in cancellous bone and in vitro experimental measurements from the literature. The angle-dependent models successfully predicted the angular dependence of phase velocity of the fast wave with direction. The root-mean-square errors of the measured versus predicted fast wave velocities were 79.2 m s -1 (angle-dependent Biot model) and 36.1 m s -1 (angle-dependent MBA model). They also predicted the fact that the slow wave is nearly independent of propagation angle for angles about 50 0 , but consistently underestimated the slow wave velocity with the root-mean-square errors of 187.2 m s -1 (angle-dependent Biot model) and 240.8 m s -1 (angle-dependent MBA model). The study indicates that the angle-dependent models reasonably replicate the acoustic anisotropy in cancellous bone

  5. Bone Loss During Spaceflight: Available Models and Counter-Measures

    Science.gov (United States)

    Morris, Jonathan; Bach, David; Geller, David

    2015-01-01

    There is ongoing concern for human health during spaceflights. Of particular interest is the uncoupling of bone remodeling and its resultant effect on calcium metabolism and bone loss. The calculated average loss of bone mineral density (BMD) is approximately 1-1.5% per month of spaceflight. The effect of decreased BMD on associated fractures in astronauts is not known. Currently on the International Space Station (ISS), bone loss is managed through dietary supplements and modifications and resistance exercise regimen. As the duration of space flights increases, a review of the current methods available for the prevention of bone loss is warranted. The goal of this project is to review and summarize recent studies that have focused on maintaining BMD during exposure to microgravity. Interventions were divided into physical (Table 1), nutritional (Table 2), or pharmacologic (Table 3) categories. Physical modalities included resistance exercise, low level vibration, and low intensity pulsed ultrasound. Nutritional interventions included altering protein, salt, and fat intake; and vitamin D supplementation. Pharmacologic interventions included the use of bisphosphonates and beta blockers. Studies reported outcomes based on bone density determined by DXA bone scan, micro-architecture of histology and microCT, and serum and urine markers of bone turnover. The ground analog models utilized to approximate osseous physiology in microgravity included human patients previously paralyzed or subjects confined to bedrest. Ground analog animal models include paralysis, immobilization and ovariectomies. As a result of the extensive research performed there is a multi-modality approach available for the management of BMD during spaceflight that includes resistance training, nutrition and dietary supplements. However, there is a paucity of literature describing a formalized tiered protocol to guide investigators through the progression from animal models to human patient ground

  6. Permeability of rapid prototyped artificial bone scaffold structures.

    Science.gov (United States)

    Lipowiecki, Marcin; Ryvolová, Markéta; Töttösi, Ákos; Kolmer, Niels; Naher, Sumsun; Brennan, Stephen A; Vázquez, Mercedes; Brabazon, Dermot

    2014-11-01

    In this work, various three-dimensional (3D) scaffolds were produced via micro-stereolithography (µ-SLA) and 3D printing (3DP) techniques. This work demonstrates the advantages and disadvantages of these two different rapid prototyping methods for production of bone scaffolds. Compared to 3DP, SLA provides for smaller feature production with better dimensional resolution and accuracy. The permeability of these structures was evaluated experimentally and via numerical simulation utilizing a newly derived Kozeny-Carman based equation for intrinsic permeability. Both experimental and simulation studies took account of porosity percentage, pore size, and pore geometry. Porosity content was varied from 30% to 70%, pore size from 0.34 mm to 3 mm, and pore geometries of cubic and hexagonal closed packed were examined. Two different fluid viscosity levels of 1 mPa · s and 3.6 mPa · s were used. The experimental and theoretical results indicated that permeability increased when larger pore size, increased fluid viscosity, and higher percentage porosity were utilized, with highest to lowest degree of significance following the same order. Higher viscosity was found to result in permeabilities 2.2 to 3.3 times higher than for water. This latter result was found to be independent of pore morphology type. As well as demonstrating method for determining design parameters most beneficial for scaffold structure design, the results also illustrate how the variations in patient's blood viscosity can be extremely important in allowing for permeability through the bone and scaffold structures. © 2014 Wiley Periodicals, Inc.

  7. Evaluating resveratrol as a therapeutic bone agent: preclinical evidence from rat models of osteoporosis.

    Science.gov (United States)

    Tou, Janet C

    2015-08-01

    Resveratrol (RSV) is a naturally occurring plant polyphenol that has potential to attenuate osteoporosis with distinct pathologies. This review evaluates preclinical evidence regarding the efficacy and safety of RSV as a therapeutic bone agent using different rat models. Limitations of these animal models are discussed, and suggestions for strengthening the experimental design of future studies are provided. The ovariectomized rat model of postmenopausal osteoporosis reported that RSV supplementation attenuated estrogen deficiency-induced bone loss and trabecular structural deterioration. RSV safety was indicated by the absence of stimulation of estrogen-sensitive tissue. Providing RSV to rats aged >6 months attenuated age-related bone mass loss and structural deterioration but produced inconsistent effects on bones in rats aged osteoporosis reported that RSV attenuated bone loss in old rats, but higher doses and longer duration supplementation before mechanical loading were required for younger rats. Limitations common to studies using rat models of osteoporosis include requirements to include animals that are skeletally mature, longer study durations, and to adjust for potential confounding effects due to altered body weight and endocrine function. Strengthening experimental design can contribute to translation of animal results to clinically relevant recommendations for humans. Published 2015. This article is U.S. Government work and is in the public domain in the USA.

  8. Structural Equation Model Trees

    Science.gov (United States)

    Brandmaier, Andreas M.; von Oertzen, Timo; McArdle, John J.; Lindenberger, Ulman

    2013-01-01

    In the behavioral and social sciences, structural equation models (SEMs) have become widely accepted as a modeling tool for the relation between latent and observed variables. SEMs can be seen as a unification of several multivariate analysis techniques. SEM Trees combine the strengths of SEMs and the decision tree paradigm by building tree…

  9. Late radiation damage in bone, bone marrow and brain vasculature, with particular emphasis upon fractionation models

    International Nuclear Information System (INIS)

    Pitkaenen, Maunu.

    1986-04-01

    X-ray induced changes in rat and human bone and bone marrow vasculature and in rat brain vasculature were measured as a function of time after irradiation and absorbed dose. The absorbed dose in the organ varied from 5 to 25 Gy for single dose irradiations and from 19 to 58 Gy for fractionated irradiations.The number of fractions varied from 3 to 10 for the rats and from 12 to 25 for the human. Blood flow changes were measured using an ''1''2''5I antipyrine or ''8''6RbCl extraction technique. The red blood cell (RBC) volume was examined by ''5''1Cr labelled red cells. Different fractionation models have been compared. Radiation induced reduction of bone and bone marrow blood flow were both time and dose dependent. Reduced blood flow 3 months after irradiation would seem to be an important factor in the subsequent atrophy of bones. With a single dose of 10 Gy the bone marrow blood flow returned to the control level by 7 months after irradiation. In the irradiated bone the RBC volume was about same as that in the control side but in bone marrow the reduction was from 32 to 59%. The dose levels predicted by the nominal standard dose (NSD) formula produced about the same damage to the rat femur seven months after irradiation when the extraction of ''8''6Rb chloride and the dry weight were concerned as the end points. However, the results suggest that the NSB formula underestimates the late radiation damage in bone marrow when a small number of large fractions are used. In the irradiated brains of the rats the blood flow was on average 20.4% higher compared to that in the control group. There was no significant difference in brain blood flow between different fractionation schemes. The value of 0.42 for the exponent of N corresponds to the average value for central nervous system tolerance in the literature. The model used may be sufficiently accurate for clinical work provided the treatment schemes used do not depart too radically from standard practice

  10. Modeling invasion of metastasizing cancer cells to bone marrow utilizing ecological principles.

    Science.gov (United States)

    Chen, Kun-Wan; Pienta, Kenneth J

    2011-10-03

    The invasion of a new species into an established ecosystem can be directly compared to the steps involved in cancer metastasis. Cancer must grow in a primary site, extravasate and survive in the circulation to then intravasate into target organ (invasive species survival in transport). Cancer cells often lay dormant at their metastatic site for a long period of time (lag period for invasive species) before proliferating (invasive spread). Proliferation in the new site has an impact on the target organ microenvironment (ecological impact) and eventually the human host (biosphere impact). Tilman has described mathematical equations for the competition between invasive species in a structured habitat. These equations were adapted to study the invasion of cancer cells into the bone marrow microenvironment as a structured habitat. A large proportion of solid tumor metastases are bone metastases, known to usurp hematopoietic stem cells (HSC) homing pathways to establish footholds in the bone marrow. This required accounting for the fact that this is the natural home of hematopoietic stem cells and that they already occupy this structured space. The adapted Tilman model of invasion dynamics is especially valuable for modeling the lag period or dormancy of cancer cells. The Tilman equations for modeling the invasion of two species into a defined space have been modified to study the invasion of cancer cells into the bone marrow microenvironment. These modified equations allow a more flexible way to model the space competition between the two cell species. The ability to model initial density, metastatic seeding into the bone marrow and growth once the cells are present, and movement of cells out of the bone marrow niche and apoptosis of cells are all aspects of the adapted equations. These equations are currently being applied to clinical data sets for verification and further refinement of the models.

  11. Structural Equation Model Trees

    Science.gov (United States)

    Brandmaier, Andreas M.; von Oertzen, Timo; McArdle, John J.; Lindenberger, Ulman

    2015-01-01

    In the behavioral and social sciences, structural equation models (SEMs) have become widely accepted as a modeling tool for the relation between latent and observed variables. SEMs can be seen as a unification of several multivariate analysis techniques. SEM Trees combine the strengths of SEMs and the decision tree paradigm by building tree structures that separate a data set recursively into subsets with significantly different parameter estimates in a SEM. SEM Trees provide means for finding covariates and covariate interactions that predict differences in structural parameters in observed as well as in latent space and facilitate theory-guided exploration of empirical data. We describe the methodology, discuss theoretical and practical implications, and demonstrate applications to a factor model and a linear growth curve model. PMID:22984789

  12. Hierarchy effect on electronic structure and core-to-valence transitions in bone tissue: perspectives in medical nanodiagnostics of mineralized bone

    Science.gov (United States)

    Samoilenko, Dmitrii O.; Avrunin, Alexander S.; Pavlychev, Andrey A.

    2017-06-01

    Electronic structure and core-to-valence transitions in bone tissue are examined in the framework of the morphological 3DSL model that takes into account (i) structural and functional organization of the skeleton in the normal and pathological conditions and (ii) peculiarities of electron wave propagation in a three-dimensional superlattice of "black-nanocrystallites-in-muddy-waters". Our focus is on the HAP-to-bone red shifts of core-to-valence transitions near Ca and P 2p and O 1s edges in single-crystal hydroxyapatite (HAP) Ca10(PO4)6(OH)2. The origin of the HAP-to-bone shift is discussed and the extended comparative analysis of the experimental data is performed. The detected spectral shift is assigned with the effect of hierarchical organization of bone tissue. This hierarchy effect on the core-to-valence transition energies is regarded as a promising tool for medical imaging and perspective pathway for nanodiagnostics of mineralized bone. Contribution to the Topical Issue "Dynamics of Systems at the Nanoscale", edited by Andrey Solov'yov and Andrei Korol.

  13. Effects of Recombinant Human Bone Morphogenetic Protein-2 on Vertical Bone Augmentation in a Canine Model.

    Science.gov (United States)

    Hsu, Yung-Ting; Al-Hezaimi, Khalid; Galindo-Moreno, Pablo; O'Valle, Francisco; Al-Rasheed, Abdulaziz; Wang, Hom-Lay

    2017-09-01

    Vertical bone augmentation (VBA) remains unpredictable and challenging for most clinicians. This study aims to compare hard tissue outcomes of VBA, with and without recombinant human bone morphogenetic protein (rhBMP)-2, under space-making titanium mesh in a canine model. Eleven male beagle dogs were used in the study. Experimental ridge defects were created to form atrophic ridges. VBA was performed via guided bone regeneration using titanium mesh and allografts. In experimental hemimandibles, rhBMP-2/absorbable collagen sponge was well mixed with allografts prior to procedures, whereas a control buffer was applied within controls. Dogs were euthanized after a 4-month healing period. Clinical and radiographic examinations were performed to assess ridge dimensional changes. In addition, specimens were used for microcomputed tomography (micro-CT) assessment and histologic analysis. Membrane exposure was found on five of 11 (45.5%) rhBMP-2-treated sites, whereas it was found on nine of 11 (81.8%) non-rhBMP-2-treated sites. Within 4 months of healing, rhBMP-2-treated sites showed better radiographic bone density, greater defect fill, and significantly more bone gain in ridge height (P 0.05). Under light microscope, predominant lamellar patterns were found in the specimen obtained from rhBMP-2 sites. With inherent limitations of the canine model and the concern of such a demanding surgical technique, current findings suggest that the presence of rhBMP-2 in a composite graft allows an increase of vertical gain, with formation of ectopic bone over the titanium mesh in comparison with non-rhBMP-2 sites.

  14. Alpha-1 Antitrypsin Gene Therapy Ameliorates Bone Loss in Ovariectomy-Induced Osteoporosis Mouse Model.

    Science.gov (United States)

    Akbar, Mohammad Ahsanul; Cao, Jay J; Lu, Yuanqing; Nardo, David; Chen, Mong-Jen; Elshikha, Ahmed S; Ahamed, Rubina; Brantly, Mark; Holliday, L Shannon; Song, Sihong

    2016-09-01

    Osteoporosis is a major healthcare burden affecting mostly postmenopausal women characterized by compromised bone strength and increased risk of fragility fracture. Although pathogenesis of this disease is complex, elevated proinflammatory cytokine production is clearly involved in bone loss at menopause. Therefore, anti-inflammatory strategies hold a great potential for the prevention of postmenopausal osteoporosis. In this study, we investigated the effect of gene therapy of recombinant adeno-associated virus (rAAV)-mediated human alpha-1 antitrypsin (hAAT), a multifunctional protein that has anti-inflammatory property, on bone loss in an ovariectomy-induced osteoporosis mouse model. Adult ovariectomized (OVX) mice were intraperitoneally (i.p.) injected with hAAT (protein therapy), rAAV8-CB-hAAT (gene therapy), or phosphate buffer saline (PBS). Age-matched and sham-operated animals were used as controls. Eight weeks after the treatment, animals were sacrificed and bone-related biomarkers and vertebral bone structure were evaluated. Results showed that hAAT gene therapy significantly decreased serum IL-6 level and receptor activator of NF-κB (RANK) gene expression in bone. Importantly, hAAT gene therapy increased bone volume/total volume and decreased structure model index (SMI) compared to PBS injection in OVX mice. These results demonstrate that hAAT gene therapy by rAAV vector efficiently mitigates bone loss possibly through inhibition of proinflammatory cytokine IL-6 and RANK gene expression. Considering the safety profile of hAAT and rAAV vector in humans, our results provide a new alternative for the treatment of osteoporosis.

  15. A Particle Model for Prediction of Cement Infiltration of Cancellous Bone in Osteoporotic Bone Augmentation

    Science.gov (United States)

    Basafa, Ehsan; Murphy, Ryan J.; Kutzer, Michael D.; Otake, Yoshito; Armand, Mehran

    2013-01-01

    Femoroplasty is a potential preventive treatment for osteoporotic hip fractures. It involves augmenting mechanical properties of the femur by injecting Polymethylmethacrylate (PMMA) bone cement. To reduce the risks involved and maximize the outcome, however, the procedure needs to be carefully planned and executed. An important part of the planning system is predicting infiltration of cement into the porous medium of cancellous bone. We used the method of Smoothed Particle Hydrodynamics (SPH) to model the flow of PMMA inside porous media. We modified the standard formulation of SPH to incorporate the extreme viscosities associated with bone cement. Darcy creeping flow of fluids through isotropic porous media was simulated and the results were compared with those reported in the literature. Further validation involved injecting PMMA cement inside porous foam blocks — osteoporotic cancellous bone surrogates — and simulating the injections using our proposed SPH model. Millimeter accuracy was obtained in comparing the simulated and actual cement shapes. Also, strong correlations were found between the simulated and the experimental data of spreading distance (R2 = 0.86) and normalized pressure (R2 = 0.90). Results suggest that the proposed model is suitable for use in an osteoporotic femoral augmentation planning framework. PMID:23840794

  16. A Particle Model for Prediction of Cement Infiltration of Cancellous Bone in Osteoporotic Bone Augmentation.

    Directory of Open Access Journals (Sweden)

    Ehsan Basafa

    Full Text Available Femoroplasty is a potential preventive treatment for osteoporotic hip fractures. It involves augmenting mechanical properties of the femur by injecting Polymethylmethacrylate (PMMA bone cement. To reduce the risks involved and maximize the outcome, however, the procedure needs to be carefully planned and executed. An important part of the planning system is predicting infiltration of cement into the porous medium of cancellous bone. We used the method of Smoothed Particle Hydrodynamics (SPH to model the flow of PMMA inside porous media. We modified the standard formulation of SPH to incorporate the extreme viscosities associated with bone cement. Darcy creeping flow of fluids through isotropic porous media was simulated and the results were compared with those reported in the literature. Further validation involved injecting PMMA cement inside porous foam blocks - osteoporotic cancellous bone surrogates - and simulating the injections using our proposed SPH model. Millimeter accuracy was obtained in comparing the simulated and actual cement shapes. Also, strong correlations were found between the simulated and the experimental data of spreading distance (R(2 = 0.86 and normalized pressure (R(2 = 0.90. Results suggest that the proposed model is suitable for use in an osteoporotic femoral augmentation planning framework.

  17. A Bone-Implant Interaction Mouse Model for Evaluating Molecular Mechanism of Biomaterials/Bone Interaction.

    Science.gov (United States)

    Liu, Wenlong; Dan, Xiuli; Wang, Ting; Lu, William W; Pan, Haobo

    2016-11-01

    The development of an optimal animal model that could provide fast assessments of the interaction between bone and orthopedic implants is essential for both preclinical and theoretical researches in the design of novel biomaterials. Compared with other animal models, mice have superiority in accessing the well-developed transgenic modification techniques (e.g., cell tracing, knockoff, knockin, and so on), which serve as powerful tools in studying molecular mechanisms. In this study, we introduced the establishment of a mouse model, which was specifically tailored for the assessment of bone-implant interaction in a load-bearing bone marrow microenvironment and could potentially allow the molecular mechanism study of biomaterials by using transgenic technologies. The detailed microsurgery procedures for developing a bone defect (Φ = 0.8 mm) at the metaphysis region of the mouse femur were recorded. According to our results, the osteoconductive and osseointegrative properties of a well-studied 45S5 bioactive glass were confirmed by utilizing our mouse model, verifying the reliability of this model. The feasibility and reliability of the present model were further checked by using other materials as objects of study. Furthermore, our results indicated that this animal model provided a more homogeneous tissue-implant interacting surface than the rat at the early stage of implantation and this is quite meaningful for conducting quantitative analysis. The availability of transgenic techniques to mechanism study of biomaterials was further testified by establishing our model on Nestin-GFP transgenic mice. Intriguingly, the distribution of Nestin + cells was demonstrated to be recruited to the surface of 45S5 glass as early as 3 days postsurgery, indicating that Nestin + lineage stem cells may participate in the subsequent regeneration process. In summary, the bone-implant interaction mouse model could serve as a potential candidate to evaluate the early stage tissue

  18. MATHEMATICAL MODELING OF BATCH ADSORPTION OF MANGANESE ONTO BONE CHAR

    OpenAIRE

    Maria, M. E.; Mansur, M. B.

    2016-01-01

    Abstract The present study investigated the dynamics of batch adsorption of manganese onto bone char by using two distinct mathematical formulations: the diffusion model and the shrinking core model. Both models assumed spherical particles and adequately described the transient behavior of metal adsorption under changing operating conditions. Comparatively, the diffusion model described the manganese adsorption better at distinct particle sizes even when small particles were used (dp ≤ 0.147 ...

  19. Clinical Application of Solid Model Based on Trabecular Tibia Bone CT Images Created by 3D Printer.

    Science.gov (United States)

    Cho, Jaemo; Park, Chan-Soo; Kim, Yeoun-Jae; Kim, Kwang Gi

    2015-07-01

    The aim of this work is to use a 3D solid model to predict the mechanical loads of human bone fracture risk associated with bone disease conditions according to biomechanical engineering parameters. We used special image processing tools for image segmentation and three-dimensional (3D) reconstruction to generate meshes, which are necessary for the production of a solid model with a 3D printer from computed tomography (CT) images of the human tibia's trabecular and cortical bones. We examined the defects of the mechanism for the tibia's trabecular bones. Image processing tools and segmentation techniques were used to analyze bone structures and produce a solid model with a 3D printer. These days, bio-imaging (CT and magnetic resonance imaging) devices are able to display and reconstruct 3D anatomical details, and diagnostics are becoming increasingly vital to the quality of patient treatment planning and clinical treatment. Furthermore, radiographic images are being used to study biomechanical systems with several aims, namely, to describe and simulate the mechanical behavior of certain anatomical systems, to analyze pathological bone conditions, to study tissues structure and properties, and to create a solid model using a 3D printer to support surgical planning and reduce experimental costs. These days, research using image processing tools and segmentation techniques to analyze bone structures to produce a solid model with a 3D printer is rapidly becoming very important.

  20. Strain of bone-implant interface and insertion torque regarding different miniscrew thread designs using an artificial bone model.

    Science.gov (United States)

    Cha, Jung-Yul; Hwang, Chung-Ju; Kwon, Sung Hwang; Jung, Han-Sung; Kim, Kwang-Mahn; Yu, Hyung Seog

    2015-06-01

    To evaluate the initial stability of dual-thread miniscrews by analyzing the strain at the bone-implant interface and insertion torque during implantation in artificial bone models with different cortical bone thicknesses. Insertion torque, and strain, measured with a five-element strain gauge in 1.0, 1.5, and 2.0-mm artificial cortical bone, during insertion of single- (OAS-T1507) and dual-thread (MPlant-U3) type self-drilling miniscrews were assessed. Both dual- and single-thread miniscrews showed greater than 7790 μstrain for all cortical bone thicknesses, and dual-thread miniscrews reached up to 19580 μstrain in 2.00 m m cortical bone. The strain of dual-thread miniscrews increased with increasing cortical bone thicknesses of 1.0-2.0mm. For single-thread miniscrews, the maximum insertion torque was relatively constant, but maximum insertion torque increased significantly in dual-thread groups with increasing cortical bone thicknesses (P bone thicknesses was significantly lower with single- than dual-thread types (P bone remodelling limit at the bone-implant interface in thick cortical bone layers. © The Author 2014. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  1. Roles of Zinc and Iron on Bone Health in a Rat Model of Osteoporosis

    Science.gov (United States)

    Yan, Danhua

    Bone is one of the most vital organs in animals, serving as both structural and protective functions. Remodeling of bone is an important indicator of bone health, and disorders in bone remodeling may lead to bone diseases such as osteoporosis. Osteoporosis increases risk of bone fracture and even death, and much more preferable to be happened in postmenopausal women due to great changes in hormones. Micronutrients, such as Zinc (Zn) and Iron (Fe), would as well influence bone health in different manners. That Zn would promote bone health is widely accepted, for the reasons Zn increases osteoblast cell proliferation and differentiation, inhibits osteoclast cell activities, and forms alkaline phosphatase that does help to maintain bone metabolism. Diseases caused by Fe overload is usually related to osteoporosis. Ferric ion could facilitate osteoclast differentiation, inhibit osteoblast and alkaline phosphatase activities, and interfere with hydroxyapatite crystal growth and depositions. However, changes of concentrations and distributions for Zn and Fe in osteoporotic bones are seldom studied. In this thesis, ovariectomized rat femur bones are used as a model of postmenopausal osteoporosis. Rats from different ages and health conditions are categorized as 6 AM (6-month age matched control), 6 OVX (6-month ovariectomized control), 12 AM (12-month age matched control), 12 OVX (12-month ovariectomized control). The trace elements Zn and Fe is studied through Synchrotron Radiation X-Ray Fluorescence (SRXRF). Elemental maps are used to observe changes in distribution, and further quantitative analysis is used to discover changes in concentration among different animal groups. Both the decrease of Zn and the increase of Fe are significant from healthy to osteoporotic bones (p0.1) is also observed over age in healthy groups. Both elements show changes in distribution, that healthy animals present a more even distribution while in OVX groups the tendency of aggregation is

  2. Kefir improves bone mass and microarchitecture in an ovariectomized rat model of postmenopausal osteoporosis.

    Science.gov (United States)

    Chen, H-L; Tung, Y-T; Chuang, C-H; Tu, M-Y; Tsai, T-C; Chang, S-Y; Chen, C-M

    2015-02-01

    Kefir treatment in ovariectomized (OVX) rats could significantly decrease the levels of bone turnover markers and prevent OVX-induced bone loss, deterioration of trabecular microarchitecture, and biomechanical dysfunction that may be due to increase intracellular calcium uptake through the TRPV6 calcium channel. Osteoporosis is a disease characterized by low bone mass and structural deterioration of bone tissue, leading to an increased fracture risk. The incidence of osteoporosis increases with age and occurs most frequently in postmenopausal women due to estrogen deficiency, as the balance between bone resorption and bone formation shifts towards increased levels of bone resorption. Among various methods of prevention and treatment for osteoporosis, an increase in calcium intake is the most commonly recommended preventive measure. Kefir is a fermented milk product made with kefir grains that degrade milk proteins into various peptides with health-promoting effects, including immunomodulating-, antithrombotic-, antimicrobial-, and calcium-absorption-enhancing bioactivities. The aim of this study is to investigate the effect of kefir on osteoporosis prophylaxis in an ovariectomized rat model. A total of 56 16-week-old female Sprague-Dawley (SD) rats were divided into 7 experimental groups: sham (normal), OVX/Mock, OVX/1X kefir (164 mg/kg BW/day), OVX/2X kefir (328 mg/kg BW/day), OVX/4X kefir (656 mg/kg BW/day), OVX/ALN (2.5 mg/kg BW/day), and OVX/REBONE (800 mg/kg BW/day). After 12-week treatment with kefir, the bone physiology in the OVX rat model was investigated. Accordingly, the aim of this study was to investigate the possible transport mechanism involved in calcium absorption using the Caco-2 human cell line. A 12-week treatment with kefir on the OVX-induced osteoporosis model reduced the levels of C-terminal telopeptides of type I collagen (CTx), bone turnover markers, and trabecular separation (Tb. Sp.). Additionally, treatment with kefir increased

  3. Genetic Dissection of Trabecular Bone Structure with Mouse Intersubspecific Consomic Strains

    Directory of Open Access Journals (Sweden)

    Taro Kataoka

    2017-10-01

    Full Text Available Trabecular bone structure has an important influence on bone strength, but little is known about its genetic regulation. To elucidate the genetic factor(s regulating trabecular bone structure, we compared the trabecular bone structures of two genetically remote mouse strains, C57BL/6J and Japanese wild mouse-derived MSM/Ms. Phenotyping by X-ray micro-CT revealed that MSM/Ms has structurally more fragile trabecular bone than C57BL/6J. Toward identification of genetic determinants for the difference in fragility of trabecular bone between the two mouse strains, we employed phenotype screening of consomic mouse strains in which each C57BL/6J chromosome is substituted by its counterpart from MSM/Ms. The results showed that many chromosomes affect trabecular bone structure, and that the consomic strain B6-Chr15MSM, carrying MSM/Ms-derived chromosome 15 (Chr15, has the lowest values for the parameters BV/TV, Tb.N, and Conn.D, and the highest values for the parameters Tb.Sp and SMI. Subsequent phenotyping of subconsomic strains for Chr15 mapped four novel trabecular bone structure-related QTL (Tbsq1-4 on mouse Chr15. These results collectively indicate that genetic regulation of trabecular bone structure is highly complex, and that even in the single Chr15, the combined action of the four Tbsqs controls the fragility of trabecular bone. Given that Tbsq4 is syntenic to human Chr 12q12-13.3, where several bone-related SNPs are assigned, further study of Tbsq4 should facilitate our understanding of the genetic regulation of bone formation in humans.

  4. Differential effects of calorie restriction and involuntary wheel running on body composition and bone structure in diet-induced obese rats

    Science.gov (United States)

    Weight reduction is recommended to reduce obesity-related health disorders. This study investigated the differential effects of weight reduction through caloric restriction and/or physical activity on bone structure and molecular characteristics of bone metabolism in an obese rat model. We tested th...

  5. Accounting for structural compliance in nanoindentation measurements of bioceramic bone scaffolds

    Science.gov (United States)

    Juan Vivanco; Joseph E. Jakes; Josh Slane; Heidi-Lynn Ploeg

    2014-01-01

    Structural properties have been shown to be critical in the osteoconductive capacity and strength of bioactive ceramic bone scaffolds. Given the cellular foam-like structure of bone scaffolds, nanoindentation has been used as a technique to assess the mechanical properties of individual components of the scaffolds. Nevertheless, nanoindents placed on scaffolds may...

  6. Association Between Insulin Resistance and Bone Structure in Nondiabetic Postmenopausal Women

    DEFF Research Database (Denmark)

    Shanbhogue, Vikram V; Finkelstein, Joel S; Bouxsein, Mary L

    2016-01-01

    CONTEXT: The clinical consequences of insulin resistance and hyperinsulinemia on bone remain largely unknown. OBJECTIVE: To evaluate the effect of insulin resistance on peripheral bone geometry, volumetric bone mineral density (vBMD), bone microarchitecture and estimated bone strength. DESIGN...... computed tomography was used to assess bone density and microstructure at the distal radius and tibia. Fasting insulin and glucose was measured and insulin resistance was estimated using homeostasis model assessment of insulin resistance (HOMA-IR) with higher values indicating greater insulin resistance...... covariates (e.g., time since menopause, cigarette smoking, physical activity, prior use of osteoporosis medications or glucocorticoids). CONCLUSIONS: In non-diabetic, postmenopausal women, insulin resistance was associated with smaller bone size, greater volumetric bone mineral density and generally...

  7. A novel standardized bone model for thermal evaluation of bone osteotomies with various irrigation methods.

    Science.gov (United States)

    Strbac, Georg D; Giannis, Katharina; Unger, Ewald; Mittlböck, Martina; Watzek, Georg; Zechner, Werner

    2014-05-01

    Based on a novel standardized bovine specimen, the aim of this study was to investigate thermal effects of different irrigation methods during intermittent and graduated drilling. Temperature changes during implant osteotomies (n = 320) of 10 and 16 mm drilling depths with various irrigation methods were investigated on manufactured uniform bone samples providing homogenous cortical and cancellous areas and analogous thermal conductivity comparable to human bone. Automated sequences were performed with surgical twist drills of 2 mm ∅ and conical drills of 3.5, 4.3 and 5 mm ∅. Real-time recording of temperature increase was done using two custom-built multichannel thermoprobes with 14 temperature sensors at a predefined distance of 1 and 2 mm to the final osteotomy. The effects of drilling depth, drilling diameter and irrigation methods on temperature changes were investigated by a linear mixed model. Using this uniform bone specimen, the greatest temperature rise was observed without any coolant supply with 29.87°C, followed by external with 28.47°C and then internal with 25.86°C and combined irrigation with 25.68°C. Significant differences (P ≤ 0.0156) between drill depths of 10 vs. 16 mm could be observed with all irrigation methods evaluated. With each of the irrigation methods, significantly higher temperature changes (P irrigation showed significantly higher temperatures (P irrigation, respectively. Significantly lower temperatures (P irrigation for the use of conical drills with various diameters and drilling depths. This fully standardized bone model provides optimized comparability for the evaluation of bone osteotomies and resulting temperature changes. As regards the efficiency of the various irrigation methods, it could be demonstrated that internal and combined irrigation appears to be more beneficial than external irrigation. © 2013 John Wiley & Sons A/S. Published by Blackwell Publishing Ltd.

  8. Physical Activity and Bone Accretion: Isotemporal Modeling and Genetic Interactions.

    Science.gov (United States)

    Mitchell, Jonathan A; Chesi, Alessandra; McCormack, Shana E; Cousminer, Diana L; Kalkwarf, Heidi J; Lappe, Joan M; Gilsanz, Vicente; Oberfield, Sharon E; Shepherd, John A; Kelly, Andrea; Grant, Struan F A; Zemel, Babette S

    2018-02-20

    To determine if replacing time spent in high and low impact physical activity (PA) predicts changes in pediatric bone mineral density (BMD) and content (BMC). We analyzed data from the longitudinal Bone Mineral Density in Childhood Study (N=2,337 with up to 7 visits). The participants were aged 5-19 years at baseline, 51.2% were female and 80.6% were non-Black. Spine, total hip, and femoral neck areal BMD (aBMD) and total body less head (TBLH) BMC Z-scores were calculated. Hours per day (h/d) spent in high and low impact PA were self-reported. Standard covariate adjusted (partition model) and time allocation sensitive isotemporal substitution modeling frameworks were applied to linear mixed models. Statistical interactions with sex, self-reported ancestry, age and bone fragility genetic scores (percentage of aBMD lowering alleles carried) were tested. In standard models, high impact PA was positively associated with bone Z-score at all four skeletal sites (e.g., TBLH-BMC Z-score: beta=0.05, P=2.0x10), whereas low impact PA was not associated with any of the bone Z-scores. In isotemporal substitution models, replacing 1 h/d of low-for-high impact PA was associated with higher bone Z-scores (e.g., TBLH-BMC Z-score: beta=0.06, P=2.9x10). Conversely, replacing 1 h/d of high-for-low impact PA was associated with lower bone Z-scores (e.g., TBLH-BMC Z-score: beta=-0.06, P=2.9x10). The substitution associations were similar for each sex and ancestry group, and for those with higher and lower genetic scores for bone fragility (P-interactions >0.05), but increased in strength among the older adolescents (P-age interactions <0.05). Time sensitive models suggest that replacing low impact PA for high impact PA would be beneficial for the growing skeleton in the majority of children.

  9. Scaling relations between bone volume and bone structure as found using 3D µCT images of the trabecular bone taken from different skeletal sites

    Science.gov (United States)

    Raeth, Christoph; Müller, Dirk; Sidorenko, Irina; Monetti, Roberto; Eckstein, Felix; Matsuura, Maiko; Lochmüller, Eva-Maria; Zysset, Philippe K.; Bauer, Jan

    2010-03-01

    According to Wolff's law bone remodels in response to the mechanical stresses it experiences so as to produce a minimal-weight structure that is adapted to its applied stresses. Here, we investigate the relations between bone volume and structure for the trabecular bone using 3D μCT images taken from different skeletal sites in vitro, namely from the distal radii (96 specimens), thoracic (73 specimens) and lumbar vertebrae (78 specimens). We determine the local structure of the trabecular network by calculating isotropic and anisotropic scaling indices (α, αz). These measures have been proven to be able to discriminate rod- from sheet-like structures and to quantify the alignment of structures with respect to a preferential direction as given by the direction of the external force. Comparing global structure measures derived from the scaling indices (mean, standard deviation) with the bone mass (BV/TV) we find that all correlations obey very accurately power laws with scaling exponents of 0.14, 0.12, 0.15 (~), -0.2, -017, -0.17 (σ(αz)), 0.09, 0.05, 0.07 (~) and -0.20, -0.11 ,-0.13 (σ(αz)) distal radius, thoracic vertebra and lumbar vertebra respectively. Thus, these relations turn out to be site-independent, albeit the mechanical stresses to which the bones of the forearm and the spine are exposed, are quite different. The similar alignment might not be in agreement with a universal validity of Wolff's law. On the other hand, such universal power law relations may allow to develop additional diagnostic means to better assess healthy and osteoporotic bone.

  10. Characterization of microgravity effects on bone structure and strength using fractal analysis

    Science.gov (United States)

    Acharya, Raj S.; Shackelford, Linda

    1995-01-01

    The effect of micro-gravity on the musculoskeletal system has been well studied. Significant changes in bone and muscle have been shown after long term space flight. Similar changes have been demonstrated due to bed rest. Bone demineralization is particularly profound in weight bearing bones. Much of the current techniques to monitor bone condition use bone mass measurements. However, bone mass measurements are not reliable to distinguish Osteoporotic and Normal subjects. It has been shown that the overlap between normals and osteoporosis is found for all of the bone mass measurement technologies: single and dual photon absorptiometry, quantitative computed tomography and direct measurement of bone area/volume on biopsy as well as radiogrammetry. A similar discordance is noted in the fact that it has not been regularly possible to find the expected correlation between severity of osteoporosis and degree of bone loss. Structural parameters such as trabecular connectivity have been proposed as features for assessing bone conditions. In this report, we use fractal analysis to characterize bone structure. We show that the fractal dimension computed with MRI images and X-Ray images of the patella are the same. Preliminary experimental results show that the fractal dimension computed from MRI images of vertebrae of human subjects before bedrest is higher than during bedrest.

  11. Effects of ionizing radiation on bone cell differentiation in an experimental murine bone cell model

    Science.gov (United States)

    Baumstark-Khan, Christa; Lau, Patrick; Hellweg, Christine; Reitz, Guenther

    During long-term space travel astronauts are exposed to a complex mixture of different radiation types under conditions of dramatically reduced weight-bearing activity. It has been validated that astronauts loose a considerable amount of bone mass at a rate up to one to two percent each month in space. Therapeutic doses of ionizing radiation cause bone damage and increase fracture risks after treatment for head-and-neck cancer and in pelvic irradiation. For low radiation doses, the possibility of a disturbed healing potential of bone was described. Radiation induced damage has been discussed to inflict mainly on immature and healing bone. Little is known about radiation effects on bone remodelling and even less on the combined action of microgravity and radiation. Bone remodelling is a life-long process performed by balanced action of cells from the osteoblast and osteoclast lineages. While osteoblasts differentiate either into bone-lining cells or into osteocytes and play a crucial role in bone matrix synthesis, osteoclasts are responsible for bone resorption. We hypothesize that the balance between bone matrix assembly by osteocytes and bone degradation by osteoclasts is modulated by microgravity as well as by ionizing radiation. To address this, a cell model consisting of murine cell lines with the potential to differentiate into bone-forming osteoblasts (OCT-1, MC3T3-E1 S24, and MC3T3-E1 S4) was used for studying radiation response after exposure to simulated components of cosmic radiation. Cells were exposed to graded doses of 150 kV X-rays, α particles (0.525 MeV/u, 160 keV/µm; PTB, Braunschweig, Germany) and accelerated heavy ions (75 MeV/u carbon, 29 keV/µm; 95 MeV/u argon, 230 keV/µm; GANIL, Caen, France). Cell survival was measured as colony forming ability; cell cycle progression was analyzed via fluorescence-activated cell scanning (FACS) by measurement of the content of propidium iodide-stained DNA, DNA damage was visualized by γH2AX

  12. Transgenic Mouse Model for Reducing Oxidative Damage in Bone

    Science.gov (United States)

    Schreurs, A.-S.; Torres, S.; Truong, T.; Kumar, A.; Alwood, J. S.; Limoli, C. L.; Globus, R. K.

    2014-01-01

    parameters. Taken together, this typically catabolic treatment (disuse and irradiation) appeared to stimulate cortical expansion in MCAT mice but not WT mice. In conclusion, these results reveal the importance of mitochondrial ROS generation in skeletal remodeling and show that MCAT mice provide a useful animal model for bone studies.

  13. Early arthritis induces disturbances at bone nanostructural level reflected in decreased tissue hardness in an animal model of arthritis.

    Science.gov (United States)

    Vidal, Bruno; Cascão, Rita; Finnilä, Mikko A J; Lopes, Inês P; Saarakkala, Simo; Zioupos, Peter; Canhão, Helena; Fonseca, João E

    2018-01-01

    Arthritis induces joint erosions and skeletal bone fragility. The main goal of this work was to analyze the early arthritis induced events at bone architecture and mechanical properties at tissue level. Eighty-eight Wistar rats were randomly housed in experimental groups, as follows: adjuvant induced arthritis (AIA) (N = 47) and a control healthy group (N = 41). Rats were monitored during 22 days for the inflammatory score, ankle perimeter and body weight and sacrificed at different time points (11 and 22 days post disease induction). Bone samples were collected for histology, micro computed tomography (micro-CT), 3-point bending and nanoindentation. Blood samples were also collected for bone turnover markers and systemic cytokine quantification. At bone tissue level, measured by nanoindentation, there was a reduction of hardness in the arthritic group, associated with an increase of the ratio of bone concentric to parallel lamellae and of the area of the osteocyte lacuna. In addition, increased bone turnover and changes in the microstructure and mechanical properties were observed in arthritic animals, since the early phase of arthritis, when compared with healthy controls. We have shown in an AIA rat model that arthritis induces very early changes at bone turnover, structural degradation and mechanical weakness. Bone tissue level is also affected since the early phase of arthritis, characterized by decreased tissue hardness associated with changes in bone lamella organization and osteocyte lacuna surface. These observations highlight the pertinence of immediate control of inflammation in the initial stages of arthritis.

  14. A coupled mechano-biochemical model for bone adaptation

    Czech Academy of Sciences Publication Activity Database

    Klika, Václav; Pérez, M. A.; García-Aznar, J. M.; Maršík, F.; Doblaré, M.

    2014-01-01

    Roč. 69, 6-7 (2014), s. 1383-1429 ISSN 0303-6812 Institutional support: RVO:61388998 Keywords : mechano-biochemical model * bone remodelling * BMU Subject RIV: BJ - Thermodynamics Impact factor: 1.846, year: 2014 http://link.springer.com/article/10.1007%2Fs00285-013-0736-9

  15. Creating an Optimal 3D Printed Model for Temporal Bone Dissection Training.

    Science.gov (United States)

    Takahashi, Kuniyuki; Morita, Yuka; Ohshima, Shinsuke; Izumi, Shuji; Kubota, Yamato; Yamamoto, Yutaka; Takahashi, Sugata; Horii, Arata

    2017-07-01

    Making a 3-dimensional (3D) temporal bone model is simple using a plaster powder bed and an inkjet printer. However, it is difficult to reproduce air-containing spaces and precise middle ear structures. The objective of this study was to overcome these problems and create a temporal bone model that would be useful both as a training tool and for preoperative simulation. Drainage holes were made to remove excess materials from air-containing spaces, ossicle ligaments were manually changed to bony structures, and small and/or soft tissue structures were colored differently while designing the 3D models. The outcomes were evaluated by 3 procedures: macroscopic and endoscopic inspection of the model, comparison of computed tomography (CT) images of the model to the original CT, and assessment of tactile sensation and reproducibility by 20 surgeons performing surgery on the model. Macroscopic and endoscopic inspection, CT images, and assessment by surgeons were in agreement in terms of reproducibility of model structures. Most structures could be reproduced, but the stapes, tympanic sinus, and mastoid air cells were unsatisfactory. Perioperative tactile sensation of the model was excellent. Although this model still does not embody perfect reproducibility, it proved sufficiently practical for use in surgical training.

  16. Statistical model of the habit and arrangement of mineral crystals in the collagen of bone

    Science.gov (United States)

    Fratzl, Peter

    1994-10-01

    Randomly colored space tesselations are considered as models for the mineral/organic structure of bone. First, it is shown that the structure function for such models is always proportional to the average form factor of the individual tiles and hence independent of the mineral density in the sample. Then the structure function is calculated for three such models: for model I, based on a hexagonal, and model 2, on a Poisson-Voronoi tesselation of the plane and for model 3, based on a random tesselation of the line. These results are compared to experimental structure functions measured by small-angle scattering and excellent agreement is obtained between model 2 and the bone from mice and rats, as well as between model 3 and calcified turkey leg tendon. Divergent conclusions following recent experiments by small-angle x-ray scattering and by electron microscopy are discussed in the light of these structural models and an explanation is proposed which might remove the discrepancy.

  17. Inclusion of periodontal ligament fibres in mandibular finite element models leads to an increase in alveolar bone strains.

    Directory of Open Access Journals (Sweden)

    Steven W McCormack

    Full Text Available Alveolar bone remodelling is vital for the success of dental implants and orthodontic treatments. However, the underlying biomechanical mechanisms, in particular the function of the periodontal ligament (PDL in bone loading and remodelling, are not well understood. The PDL is a soft fibrous connective tissue that joins the tooth root to the alveolar bone and plays a critical role in the transmission of loads from the tooth to the surrounding bone. However, due to its complex structure, small size and location within the tooth socket it is difficult to study in vivo. Finite element analysis (FEA is an ideal tool with which to investigate the role of the PDL, however inclusion of the PDL in FE models is complex and time consuming, therefore consideration must be given to how it is included. The aim of this study was to investigate the effects of including the PDL and its fibrous structure in mandibular finite element models. A high-resolution model of a human molar region was created from micro-computed tomography scans. This is the first time that the fibrous structure of the PDL has been included in a model with realistic tooth and bone geometry. The results show that omission of the PDL creates a more rigid model, reducing the strains observed in the mandibular corpus which are of interest when considering mandibular functional morphology. How the PDL is modelled also affects the strains. The inclusion of PDL fibres alters the strains in the mandibular bone, increasing the strains in the tooth socket compared to PDL modelled without fibres. As strains in the alveolar bone are thought to play a key role in bone remodelling during orthodontic tooth movement, future FE analyses aimed at improving our understanding and management of orthodontic treatment should include the fibrous structure of the PDL.

  18. ECONGAS - model structure

    International Nuclear Information System (INIS)

    1997-01-01

    This report documents a numerical simulation model of the natural gas market in Germany, France, the Netherlands and Belgium. It is a part of a project called ''Internationalization and structural change in the gas market'' aiming to enhance the understanding of the factors behind the current and upcoming changes in the European gas market, especially the downstream part of the gas chain. The model takes European border prices of gas as given, adds transmission and distribution cost and profit margins as well as gas taxes to calculate gas prices. The model includes demand sub-models for households, chemical industry, other industry, the commercial sector and electricity generation. Demand responses to price changes are assumed to take time, and the long run effects are significantly larger than the short run effects. For the household sector and the electricity sector, the dynamics are modeled by distinguishing between energy use in the old and new capital stock. In addition to prices and the activity level (GDP), the model includes the extension of the gas network as a potentially important variable in explaining the development of gas demand. The properties of numerical simulation models are often described by dynamic multipliers, which describe the behaviour of important variables when key explanatory variables are changed. At the end, the report shows the results of a model experiment where the costs in transmission and distribution were reduced. 6 refs., 9 figs., 1 tab

  19. ECONGAS - model structure

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-12-31

    This report documents a numerical simulation model of the natural gas market in Germany, France, the Netherlands and Belgium. It is a part of a project called ``Internationalization and structural change in the gas market`` aiming to enhance the understanding of the factors behind the current and upcoming changes in the European gas market, especially the downstream part of the gas chain. The model takes European border prices of gas as given, adds transmission and distribution cost and profit margins as well as gas taxes to calculate gas prices. The model includes demand sub-models for households, chemical industry, other industry, the commercial sector and electricity generation. Demand responses to price changes are assumed to take time, and the long run effects are significantly larger than the short run effects. For the household sector and the electricity sector, the dynamics are modeled by distinguishing between energy use in the old and new capital stock. In addition to prices and the activity level (GDP), the model includes the extension of the gas network as a potentially important variable in explaining the development of gas demand. The properties of numerical simulation models are often described by dynamic multipliers, which describe the behaviour of important variables when key explanatory variables are changed. At the end, the report shows the results of a model experiment where the costs in transmission and distribution were reduced. 6 refs., 9 figs., 1 tab.

  20. An anisotropic elastic-viscoplastic damage model for bone tissue.

    Science.gov (United States)

    Schwiedrzik, J J; Zysset, P K

    2013-04-01

    A new anisotropic elastic-viscoplastic damage constitutive model for bone is proposed using an eccentric elliptical yield criterion and nonlinear isotropic hardening. A micromechanics-based multiscale homogenization scheme proposed by Reisinger et al. is used to obtain the effective elastic properties of lamellar bone. The dissipative process in bone is modeled as viscoplastic deformation coupled to damage. The model is based on an orthotropic ecuntric elliptical criterion in stress space. In order to simplify material identification, an eccentric elliptical isotropic yield surface was defined in strain space, which is transformed to a stress-based criterion by means of the damaged compliance tensor. Viscoplasticity is implemented by means of the continuous Perzyna formulation. Damage is modeled by a scalar function of the accumulated plastic strain [Formula: see text] , reducing all element s of the stiffness matrix. A polynomial flow rule is proposed in order to capture the rate-dependent post-yield behavior of lamellar bone. A numerical algorithm to perform the back projection on the rate-dependent yield surface has been developed and implemented in the commercial finite element solver Abaqus/Standard as a user subroutine UMAT. A consistent tangent operator has been derived and implemented in order to ensure quadratic convergence. Correct implementation of the algorithm, convergence, and accuracy of the tangent operator was tested by means of strain- and stress-based single element tests. A finite element simulation of nano- indentation in lamellar bone was finally performed in order to show the abilities of the newly developed constitutive model.

  1. PERCEPTION OF MEDICAL STUDENTS TOWARDS ARTIFICIAL BONES AND POP MODELS OF VISCERA

    OpenAIRE

    Sumit Tulshidas Patil; Nazia Quadir; Rashmi Deopujari; Vivekanand Gajbhiye

    2015-01-01

    Background: In learning of anatomy, bones and viscera are very important. Now days, artificial bones are replacing the original bones for study purpose due to unavailability. Original viscera are available for students only at dissection hours. So we have tried to find out perception of medical students towards artificial bones and POP models of viscera. Materials and Methods: We had prepared a questionnaire consisting of 20 questions, 10 related to bones and 10 related to the POP models o...

  2. A Novel Immune-Intact Mouse Model of Prostate Cancer Bone Metastasis: Mechanisms of Chemotaxis and Bone Colonization

    Science.gov (United States)

    2017-10-01

    of prostate tumor cells that have already colonized the bone, and are largely ineffective in prolonging the survival of human prostate cancer patients...AWARD NUMBER: W81XWH-16-1-0174 TITLE: A Novel Immune-Intact Mouse Model of Prostate Cancer Bone Metastasis: Mechanisms of Chemotaxis and Bone... Colonization PRINCIPAL INVESTIGATOR: Srinivas Nandana CONTRACTING ORGANIZATION: Cedars-Sinai Medical Center Los Angeles, CA, 90048 REPORT DATE

  3. Characterization and three-dimensional reconstruction of synthetic bone model foams

    Energy Technology Data Exchange (ETDEWEB)

    Gómez, S. [Interdepartment Research Group for the Applied Scientific Collaboration (IRGASC), Division of Biomaterials and Bioengineering, Technical University of Catalonia (UPC), Avda. Diagonal 647, E-08028 Barcelona (Spain); Vlad, M.D. [Interdepartment Research Group for the Applied Scientific Collaboration (IRGASC), Division of Biomaterials and Bioengineering, Technical University of Catalonia (UPC), Avda. Diagonal 647, E-08028 Barcelona (Spain); Faculty of Medical Bioengineering, “Gr. T. Popa” University of Medicine and Pharmacy, Str. Kogalniceanu 9-13, 700454 Iasi (Romania); López, J. [Interdepartment Research Group for the Applied Scientific Collaboration (IRGASC), Division of Biomaterials and Bioengineering, Technical University of Catalonia (UPC), Avda. Diagonal 647, E-08028 Barcelona (Spain); Navarro, M. [Centre de Biotecnologia Animal i de Teràpia Gènica (CBATEG), Departament de Sanitat i d' Anatomia Animals, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Cerdanyola del Vallès (Spain); Fernández, E., E-mail: enrique.fernandez@upc.edu [Interdepartment Research Group for the Applied Scientific Collaboration (IRGASC), Division of Biomaterials and Bioengineering, Technical University of Catalonia (UPC), Avda. Diagonal 647, E-08028 Barcelona (Spain)

    2013-08-01

    Sawbones© open-cell foams with different porosity grades are being used as synthetic bone-like models for in vitro mechanical and infiltration experiments. However, a comprehensive characterization of these foams is not available and there is a lack of reliable information about them. For this reason two of these foams (Refs. 1522-505 and -507) have been characterized at the micro architectural level by scanning electron microscopy, computed tomography and image data analysis. BoneJ open software and ImageJ open software were used to obtain the characteristic histomorphometric parameters and the three dimensional virtual models of the foams. The results showed that both foams, while having different macro porosities, appeared undistinguishable at the micro scale. Moreover, the micro structural features resembled those of osteoporotic rather than healthy trabecular bone. It is concluded that Sawbones© foams behave reasonably as synthetic bone-like models. Consequently, their use is recommended for in vitro comparison purposes of both mechanical and infiltration testing performed in real vertebra. Finally, the virtual models obtained, which are available under request, can favour comparisons between future self-similar in vitro experiments and computer simulations. - Highlights: • Sawbones© model foams have been scanned by μ-CT. • Histomorphometric indices and 3D virtual models have been obtained. • The results will be of use to understand biocement vertebra infiltration studies.

  4. Bone structural changes after gastric bypass surgery evaluated by HR-pQCT

    DEFF Research Database (Denmark)

    Shanbhogue, Vikram V; Støving, René Klinkby; Frederiksen, Katrine Hartmund

    2017-01-01

    OBJECTIVE, DESIGN AND METHODS: Roux-en-Y gastric bypass (RYGB) has proved successful in attaining sustained weight loss but may lead to metabolic bone disease. To assess impact on bone mass and structure, we measured a real bone mineral density at the hip and spine by dual-energy X-ray absorptiom......OBJECTIVE, DESIGN AND METHODS: Roux-en-Y gastric bypass (RYGB) has proved successful in attaining sustained weight loss but may lead to metabolic bone disease. To assess impact on bone mass and structure, we measured a real bone mineral density at the hip and spine by dual-energy X...... of increased risk of developing osteoporosis and fragility fractures remain an important concern....

  5. Engineered bone from bone marrow stromal cells: a structural study by an advanced x-ray microdiffraction technique

    International Nuclear Information System (INIS)

    Cedola, A; Mastrogiacomo, M; Burghammer, M; Komlev, V; Giannoni, P; Favia, A; Cancedda, R; Rustichelli, F; Lagomarsino, S

    2006-01-01

    The mechanism of mineralized matrix deposition was studied in a tissue engineering approach in which bone tissue is formed when porous ceramic constructs are loaded with bone marrow stromal cells and implanted in vivo. We investigated the local interaction between the mineral crystals of the engineered bone and the biomaterial by means of microdiffraction, using a set-up based on an x-ray waveguide. We demonstrated that the newly formed bone is well organized inside the scaffold pore, following the growth model of natural bone. Combining wide angle (WAXS) and small angle (SAXS) x-ray scattering with high spatial resolution, we were able to determine the orientation of the crystallographic c-axis inside the bone crystals, and the orientation of the mineral crystals and collagen micro-fibrils with respect to the scaffold. In this work we analysed six samples and for each of them two pores were studied in detail. Similar results were obtained in all cases but we report here only the most significant sample. (note)

  6. A humanised tissue-engineered bone model allows species-specific breast cancer-related bone metastasis in vivo.

    Science.gov (United States)

    Quent, Vmc; Taubenberger, A V; Reichert, J C; Martine, L C; Clements, J A; Hutmacher, D W; Loessner, D

    2018-02-01

    Bone metastases frequently occur in the advanced stages of breast cancer. At this stage, the disease is deemed incurable. To date, the mechanisms of breast cancer-related metastasis to bone are poorly understood. This may be attributed to the lack of appropriate animal models to investigate the complex cancer cell-bone interactions. In this study, two established tissue-engineered bone constructs (TEBCs) were applied to a breast cancer-related metastasis model. A cylindrical medical-grade polycaprolactone-tricalcium phosphate scaffold produced by fused deposition modelling (scaffold 1) was compared with a tubular calcium phosphate-coated polycaprolactone scaffold fabricated by solution electrospinning (scaffold 2) for their potential to generate ectopic humanised bone in NOD/SCID mice. While scaffold 1 was found not suitable to generate a sufficient amount of ectopic bone tissue due to poor ectopic integration, scaffold 2 showed excellent integration into the host tissue, leading to bone formation. To mimic breast cancer cell colonisation to the bone, MDA-MB-231, SUM1315, and MDA-MB-231BO breast cancer cells were cultured in polyethylene glycol-based hydrogels and implanted adjacent to the TEBCs. Histological analysis indicated that the breast cancer cells induced an osteoclastic reaction in the TEBCs, demonstrating analogies to breast cancer-related bone metastasis seen in patients. Copyright © 2017 John Wiley & Sons, Ltd.

  7. Modelization of three-dimensional bone micro-architecture using Markov random fields with a multi-level clique system

    International Nuclear Information System (INIS)

    Lamotte, T.; Dinten, J.M.; Peyrin, F.

    2004-01-01

    Imaging trabecular bone micro-architecture in vivo non-invasively is still a challenging issue due to the complexity and small size of the structure. Thus, having a realistic 3D model of bone micro-architecture could be useful in image segmentation or image reconstruction. The goal of this work was to develop a 3D model of trabecular bone micro-architecture which can be seen as a problem of texture synthesis. We investigated a statistical model based on 3D Markov Random Fields (MRF's). Due to the Hammersley-Clifford theorem MRF's may equivalently be defined by an energy function on some set of cliques. In order to model 3D binary bone texture images (bone / background), we first used a particular well-known subclass of MRFs: the Ising model. The local energy function at some voxel depends on the closest neighbors of the voxels and on some parameters which control the shape and the proportion of bone. However, simulations yielded textures organized as connected clusters which even when varying the parameters did not approach the complexity of bone micro-architecture. Then, we introduced a second level of cliques taking into account neighbors located at some distance d from the site s and a new set of cliques allowing to control the plate thickness and spacing. The 3D bone texture images generated using the proposed model were analyzed using the usual bone-architecture quantification tools in order to relate the parameters of the MRF model to the characteristic parameters of bone micro-architecture (trabecular spacing, trabecular thickness, number of trabeculae...). (authors)

  8. Modelization of three-dimensional bone micro-architecture using Markov random fields with a multi-level clique system

    Energy Technology Data Exchange (ETDEWEB)

    Lamotte, T.; Dinten, J.M. [CEA Grenoble (DTBS/STD), Lab. d' Electronique et de Technologie de l' Informatique, LETI, 38 (France); Peyrin, F. [Institut National des Sciences Appliquees (INSA), CREATIS, UMR CNRS 5515, inserm U630, 69 - Villeurbanne (France)

    2004-07-01

    Imaging trabecular bone micro-architecture in vivo non-invasively is still a challenging issue due to the complexity and small size of the structure. Thus, having a realistic 3D model of bone micro-architecture could be useful in image segmentation or image reconstruction. The goal of this work was to develop a 3D model of trabecular bone micro-architecture which can be seen as a problem of texture synthesis. We investigated a statistical model based on 3D Markov Random Fields (MRF's). Due to the Hammersley-Clifford theorem MRF's may equivalently be defined by an energy function on some set of cliques. In order to model 3D binary bone texture images (bone / background), we first used a particular well-known subclass of MRFs: the Ising model. The local energy function at some voxel depends on the closest neighbors of the voxels and on some parameters which control the shape and the proportion of bone. However, simulations yielded textures organized as connected clusters which even when varying the parameters did not approach the complexity of bone micro-architecture. Then, we introduced a second level of cliques taking into account neighbors located at some distance d from the site s and a new set of cliques allowing to control the plate thickness and spacing. The 3D bone texture images generated using the proposed model were analyzed using the usual bone-architecture quantification tools in order to relate the parameters of the MRF model to the characteristic parameters of bone micro-architecture (trabecular spacing, trabecular thickness, number of trabeculae...). (authors)

  9. Mathematical Model of Bone Regeneration in a Porous Implant

    Science.gov (United States)

    Maslov, L. B.

    2017-07-01

    A mathematical model of the reparative regeneration of bone tissue governed by the law of cell differentiation and action of an external periodic mechanical loading is presented. The model allows one to study the recovery processes of injured human locomotor system elements under a dynamic loading and to theoretically substantiate the choice of an optimum periodic impact on the defective tissues for their fastest and steady healing.

  10. Bone invading NSCLC cells produce IL-7: mice model and human histologic data

    International Nuclear Information System (INIS)

    Roato, Ilaria; Mussa, Antonio; Ferracini, Riccardo; Caldo, Davide; Godio, Laura; D'Amico, Lucia; Giannoni, Paolo; Morello, Emanuela; Quarto, Rodolfo; Molfetta, Luigi; Buracco, Paolo

    2010-01-01

    Bone metastases are a common and dismal consequence of lung cancer that is a leading cause of death. The role of IL-7 in promoting bone metastases has been previously investigated in NSCLC, but many aspects remain to be disclosed. To further study IL-7 function in bone metastasis, we developed a human-in-mice model of bone aggression by NSCLC and analyzed human bone metastasis biopsies. We used NOD/SCID mice implanted with human bone. After bone engraftment, two groups of mice were injected subcutaneously with A549, a human NSCLC cell line, either close or at the contralateral flank to the human bone implant, while a third control group did not receive cancer cells. Tumor and bone vitality and IL-7 expression were assessed in implanted bone, affected or not by A549. Serum IL-7 levels were evaluated by ELISA. IL-7 immunohistochemistry was performed on 10 human bone NSCLC metastasis biopsies for comparison. At 12 weeks after bone implant, we observed osteogenic activity and neovascularization, confirming bone vitality. Tumor aggressive cells implanted close to human bone invaded the bone tissue. The bone-aggressive cancer cells were positive for IL-7 staining both in the mice model and in human biopsies. Higher IL-7 serum levels were found in mice injected with A549 cells close to the bone implant compared to mice injected with A549 cells in the flank opposite to the bone implant. We demonstrated that bone-invading cells express and produce IL-7, which is known to promote osteoclast activation and osteolytic lesions. Tumor-bone interaction increases IL-7 production, with an increase in IL-7 serum levels. The presented mice model of bone invasion by contiguous tumor is suitable to study bone-tumor cell interaction. IL-7 plays a role in the first steps of metastatic process

  11. Model for the induction of bone cancer by 224Ra

    International Nuclear Information System (INIS)

    Groer, P.G.; Marshall, J.H.

    1976-01-01

    A mathematical model for the transformation of normal endosteal cells into malignant tumor cells by α irradiation is applied to 224 Ra. The model postulates that a normal endosteal cell near the bone surface is transformed into a malignant cell by three consecutive events. The first two events are the initiation events. The probability of their occurrence is proportional to the absorbed endosteal dose and they generate dormant tumor cells. These dormant tumor cells are promoted by the third event, the promotion event. The probability of this last event is proportional to the rate of bone remodeling but independent of the radiation dose. In competition with these transforming events is the killing of any endosteal cell by α irradiation. Killing is balanced by replacement of killed endosteal cells by normal stem cells. This model provides the following interesting predictions for the human 224 Ra cases: after the decay of 224 Ra the tumor rate decreases exponentially at a rate proportional to the bone turnover rate; for exposure to the same dose the model predicts an increased number of tumors for protracted exposure (i.e., exposure at a lower dose rate). Implications of this model for the therapy of ankylosing spondylitis are discussed. Statistical procedures are suggested for comparison of this theoretical model with the existing data on the induction of osteosarcomas by 224 Ra in man

  12. Review - bioactive glass implants for potential application in structural bone repair

    Directory of Open Access Journals (Sweden)

    Rahaman Mohamed N.

    2017-09-01

    Full Text Available Bioactive glass particles andweak scaffolds have been used to heal small contained bone defects but an unmet challenge is the development of bioactive glass implants with the requisite mechanical reliability and in vivo performance to heal structural bone defects. Inadequate mechanical strength and a brittle mechanical response have been key concerns in the use of bioactive glass scaffolds in structural bone repair. Recent research has shown the capacity to create strong porous bioactive glass scaffolds and the ability of these scaffolds to heal segmental bone defects in small and large rodents at a rate comparable to autogenous bone grafts. Loading these strong porous scaffolds with bone morphogenetic protein-2 can significantly enhance their ability to regenerate bone. Recentwork has also shown that coating the external surface of strong porous scaffolds with an adherent biodegradable polymer can dramatically improve their load-bearing capacity in flexural loading and their work of fracture (a measure of toughness. These tough and strong bioactive glass-polymer composites with an internal architecture conducive to bone infiltration could provide optimal synthetic implants for structural bone repair.

  13. A high-fat diet increases body weight and circulating estradiol concentrations but does not improve bone structural properties in ovariectomized mice.

    Science.gov (United States)

    Cao, Jay J; Gregoire, Brian R

    2016-04-01

    Bone health is influenced by body mass and estrogen. The objective of the study was to determine whether high-fat diet-induced obesity affects bone structure and alters markers of bone turnover in ovariectomized (OVX) mice. We hypothesized that a high-fat diet would increase body weight gain and serum estradiol levels in OVX mice but would not improve bone structural parameter in OVX mice. Thirty-five C57BL/6 mice were either sham operated or OVX at the age of 4 months and then fed either a normal-fat diet (10% energy as fat) or a high-fat diet (45% energy as fat with extra fat from lard) ad libitum for 11 weeks. Ovariectomy increased body weight, serum tartrate-resistant acid phosphatase concentration, and expression of cathepsin K in bone; decreased serum estradiol concentration; and induced significant bone loss manifested by decreased bone volume/total volume (BV/TV), connectivity density (Conn.D), trabecular number, and trabecular thickness with increased trabecular separation and structural model index (P diet increased body weight (P diet had lower BV/TV, Conn.D, trabecular number, trabecular thickness, and higher structural model index and trabecular separation than did sham mice fed the normal-fat diet. These findings indicate that increased body weight and elevated serum estradiol concentration induced by a high-fat diet do not mitigate ovariectomy-induced bone loss in mice. Published by Elsevier Inc.

  14. Building a Structural Model: Parameterization and Structurality

    Directory of Open Access Journals (Sweden)

    Michel Mouchart

    2016-04-01

    Full Text Available A specific concept of structural model is used as a background for discussing the structurality of its parameterization. Conditions for a structural model to be also causal are examined. Difficulties and pitfalls arising from the parameterization are analyzed. In particular, pitfalls when considering alternative parameterizations of a same model are shown to have lead to ungrounded conclusions in the literature. Discussions of observationally equivalent models related to different economic mechanisms are used to make clear the connection between an economically meaningful parameterization and an economically meaningful decomposition of a complex model. The design of economic policy is used for drawing some practical implications of the proposed analysis.

  15. A new approach for assigning bone material properties from CT images into finite element models.

    Science.gov (United States)

    Chen, G; Schmutz, B; Epari, D; Rathnayaka, K; Ibrahim, S; Schuetz, M A; Pearcy, M J

    2010-03-22

    Generation of subject-specific finite element (FE) models from computed tomography (CT) datasets is of significance for application of the FE analysis to bone structures. A great challenge that remains is the automatic assignment of bone material properties from CT Hounsfield Units into finite element models. This paper proposes a new assignment approach, in which material properties are directly assigned to each integration point. Instead of modifying the dataset of FE models, the proposed approach divides the assignment procedure into two steps: generating the data file of the image intensity of a bone in a MATLAB program and reading the file into ABAQUS via user subroutines. Its accuracy has been validated by assigning the density of a bone phantom into a FE model. The proposed approach has been applied to the FE model of a sheep tibia and its applicability tested on a variety of element types. The proposed assignment approach is simple and illustrative. It can be easily modified to fit users' situations. Copyright (c) 2009 Elsevier Ltd. All rights reserved.

  16. Bone Marrow Stromal Cells Contribute to Bone Formation Following Infusion into Femoral Cavities of a Mouse Model of Osteogenesis Imperfecta

    Science.gov (United States)

    Li, Feng; Wang, Xujun; Niyibizi, Christopher

    2010-01-01

    Currently, there are conflicting data in literature regarding contribution of bone marrow stromal cells (BMSCs) to bone formation when the cells are systemically delivered in recipient animals. To understand if BMSCs contribute to bone cell phenotype and bone formation in osteogenesis imperfecta bones (OI), MSCs marked with GFP were directly infused into the femurs of a mouse model of OI (oim). The contribution of the cells to the cell phenotype and bone formation was assessed by histology, immunohistochemistry and biomechanical loading of recipient bones. Two weeks following infusion of BMSCs, histological examination of the recipient femurs demonstrated presence of new bone when compared to femurs injected with saline which showed little or no bone formation. The new bone contained few donor cells as demonstrated by GFP fluorescence. At six weeks following cell injection, new bone was still detectable in the recipient femurs but was enhanced by injection of the cells suspended in pepsin solublized type I collagen. Immunofluorescence and immunohistochemical staining showed that donor GFP positive cells in the new bone were localized with osteocalcin expressing cells suggesting that the cells differentiated into osteoblasts in vivo. Biomechanical loading to failure in thee point bending, revealed that, femurs infused with BMSCs in PBS or in soluble type I collagen were biomechanically stronger than those injected with PBS or type I collagen alone. Taken together, the results indicate that transplanted cells differentiated into osteoblasts in vivo and contributed to bone formation in vivo; we also speculate that donor cells induced differentiation or recruitment of endogenous cells to initiate reparative process at early stages following transplantation. PMID:20570757

  17. Methods and theory in bone modeling drift: comparing spatial analyses of primary bone distributions in the human humerus.

    Science.gov (United States)

    Maggiano, Corey M; Maggiano, Isabel S; Tiesler, Vera G; Chi-Keb, Julio R; Stout, Sam D

    2016-01-01

    This study compares two novel methods quantifying bone shaft tissue distributions, and relates observations on human humeral growth patterns for applications in anthropological and anatomical research. Microstructural variation in compact bone occurs due to developmental and mechanically adaptive circumstances that are 'recorded' by forming bone and are important for interpretations of growth, health, physical activity, adaptation, and identity in the past and present. Those interpretations hinge on a detailed understanding of the modeling process by which bones achieve their diametric shape, diaphyseal curvature, and general position relative to other elements. Bone modeling is a complex aspect of growth, potentially causing the shaft to drift transversely through formation and resorption on opposing cortices. Unfortunately, the specifics of modeling drift are largely unknown for most skeletal elements. Moreover, bone modeling has seen little quantitative methodological development compared with secondary bone processes, such as intracortical remodeling. The techniques proposed here, starburst point-count and 45° cross-polarization hand-drawn histomorphometry, permit the statistical and populational analysis of human primary tissue distributions and provide similar results despite being suitable for different applications. This analysis of a pooled archaeological and modern skeletal sample confirms the importance of extreme asymmetry in bone modeling as a major determinant of microstructural variation in diaphyses. Specifically, humeral drift is posteromedial in the human humerus, accompanied by a significant rotational trend. In general, results encourage the usage of endocortical primary bone distributions as an indicator and summary of bone modeling drift, enabling quantitative analysis by direction and proportion in other elements and populations. © 2015 Anatomical Society.

  18. Trabecular bone structure and strength - remodelling and repair

    DEFF Research Database (Denmark)

    Mosekilde, Lis; Ebbesen, Ebbe Nils; Erikstrup, Lise Tornvig

    2000-01-01

    The strength of the spinal trabecular bone declines by a factor of 4-5 from the age of 20 to 80 years. At the same time, the volumetric (apparent) density declines by a factor of only 2. This discrepancy can be explained by the known power relationship between density and strength; this power rel......; and the hydraulic effect of the bone marrow. In order to answer these questions, more in vitro and in vivo studies on human bone in relation to aging, to immobilisation, to exercise and in relation to different treatment regimens are needed.......The strength of the spinal trabecular bone declines by a factor of 4-5 from the age of 20 to 80 years. At the same time, the volumetric (apparent) density declines by a factor of only 2. This discrepancy can be explained by the known power relationship between density and strength; this power...

  19. Comparison of the influences of structural characteristics on bulk mechanical behaviour: experimental study using a bone surrogate.

    Science.gov (United States)

    Levasseur, A; Ploeg, H-L; Petit, Y

    2012-01-01

    An experimental study was conducted to classify the influence of trabecular architecture and cortical shell thickness on the mechanical properties using a bone surrogate. Thirty-six rectangular prisms and 18 vertebral-shaped specimens were fabricated with fused deposition modelling (FDM) as a bone surrogate with controlled structural characteristics (cortical wall thickness, strut spacing, strut angle and strut orientation). The apparent density of the FDM specimens was evaluated using quantitative computed tomography (QCT) imaging and related to the apparent elastic modulus measured with compression testing. The effects of the structural parameters on the apparent elastic modulus were analysed using analysis of variance (ANOVA). The results obtained corroborate that the structural parameters have a significant effect on the apparent mechanical properties of the bulk material. The cortical shell thickness was found to have more influence than trabecular architecture. Therefore, accurate modelling of the cortical shell thickness should be considered more important than trabecular architecture in development of bone finite element models and bone surrogates.

  20. Edentulation alters material properties of cortical bone in the human craniofacial skeleton: functional implications for craniofacial structure in primate evolution

    Science.gov (United States)

    Dechow, Paul C.; Wang, Qian; Peterson, Jill

    2011-01-01

    Skeletal adaptations to reduced function are an important source of skeletal variation and may be indicative of environmental pressures that lead to evolutionary changes. Humans serve as a model animal to investigate the effects of loss of craniofacial function through edentulation. In the human maxilla, it is known that edentulation leads to significant changes in skeletal structure such as residual ridge resorption and loss of cortical thickness. However, little is known about changes in bone tissue structure and material properties, which are also important for understanding skeletal mechanics but are often ignored. The aims of this study were to determine cortical material properties in edentulous crania and to evaluate differences with dentate crania and thus examine the effects of loss of function on craniofacial structure. Cortical bone samples from fifteen edentulous human skulls were measured for thickness and density. Elastic properties and directions of maximum stiffness were determined by using ultrasonic techniques. These data were compared to those from dentate crania reported in a previous investigation. Cortical bone from all regions of the facial skeleton of edentulous individuals is thinner than in dentate skulls. Elastic and shear moduli, and density are similar or greater in the zygoma and cranial vault of edentulous individuals, while these properties are less in the maxilla. Most cortical bone, especially in edentulous maxillae, has reduced directional orientation. The loss of significant occlusal loads following edentulation may contribute to the change in material properties and the loss of orientation over time during the normal process of bone remodeling. These results suggest that area-specific cortical microstructural changes accompany bone resorption following edentulation. They also suggest that functional forces are important for maintaining bone mass throughout the craniofacial skeleton, even in areas such as the browridges, which

  1. PTH (1-84) Replacement Therapy in Hypoparathyroidism: Effects on bone metabolism and structure

    DEFF Research Database (Denmark)

    Sikjær, Tanja Tvistholm; Rejnmark, Lars; Tietze, Anna

    Conventional treatment of hypoparathyroidism (hypoPT) with calcium supplements and active vitamin D analogues causes reduced bone turnover and over-mineralized bone. We studied 62 patients with known hypoPT randomized into 2 groups of treatment with either PTH (1–84) 100 µg/d s.c. or placebo......, as an add-on therapy. We investigated the changes in bone structure and density using µCT in 44 iliac crest bone biopsies (23 on PTH treatment) obtained after 24-wks of treatment. Trabecular tunnelling was evident in 11 (48%) biopsies from the PTH-group, whereas no tunnelling was detected in the placebo...... group. Patients showing tunnelling had significantly higher levels of biochemical markers of bone resorption (NTX and CTX) and formation (osteocalcin, bone specific alkaline phosphatase, PINP). Compared with placebo, PTH-treatment resulted in lower trabecular thickness (Tb.Th*) (p

  2. PTH (1-84) Replacement Therapy in Hypoparathyroidism: Effects on bone metabolism and structure

    DEFF Research Database (Denmark)

    Sikjær, Tanja Tvistholm; Rejnmark, Lars; Tietze, Anna

    2011-01-01

    Conventional treatment of hypoparathyroidism (hypoPT) with calcium supplements and active vitamin D analogues causes reduced bone turnover and over-mineralized bone. We studied 62 patients with known hypoPT randomized into 2 groups of treatment with either PTH (1–84) 100 µg/d s.c. or placebo......, as an add-on therapy. We investigated the changes in bone structure and density using µCT in 44 iliac crest bone biopsies (23 on PTH treatment) obtained after 24-wks of treatment. Trabecular tunnelling was evident in 11 (48%) biopsies from the PTH-group, whereas no tunnelling was detected in the placebo...... group. Patients showing tunnelling had significantly higher levels of biochemical markers of bone resorption (NTX and CTX) and formation (osteocalcin, bone specific alkaline phosphatase, PINP). Compared with placebo, PTH-treatment resulted in lower trabecular thickness (Tb.Th*) (p

  3. Bone Structural Changes and Estimated Strength After Gastric Bypass Surgery Evaluated by HR-pQCT

    DEFF Research Database (Denmark)

    Frederiksen, Katrine Diemer; Hanson, Stine; Hansen, Stinus

    2016-01-01

    Roux-en-Y gastric bypass surgery (RYGB) is an effective treatment of morbid obesity, with positive effects on obesity-related complications. The treatment is associated with bone loss, which in turn might increase fracture risk. The aim of this study was to evaluate changes in bone mineral densit...... increased risk of fracture in bariatric patients after surgery. We only observed bone structural changes in the weight-bearing bone, which indicates that mechanical un-loading is the primary mediator.......Roux-en-Y gastric bypass surgery (RYGB) is an effective treatment of morbid obesity, with positive effects on obesity-related complications. The treatment is associated with bone loss, which in turn might increase fracture risk. The aim of this study was to evaluate changes in bone mineral density...

  4. Bone structural changes after gastric bypass surgery evaluated by HR-pQCT

    DEFF Research Database (Denmark)

    Shanbhogue, Vikram Vinod; Støving, René Klinkby; Frederiksen, Katrine Diemer

    2017-01-01

    Objective, design and methods: Roux-en-Y gastric bypass (RYGB) has proved successful in attaining sustained weight loss but may lead to metabolic bone disease. To assess impact on bone mass and structure, we measured areal bone mineral density at the hip and spine by dual-energy x-ray absorptiome......Objective, design and methods: Roux-en-Y gastric bypass (RYGB) has proved successful in attaining sustained weight loss but may lead to metabolic bone disease. To assess impact on bone mass and structure, we measured areal bone mineral density at the hip and spine by dual-energy x...... in estimated bone strength at the radius and tibia respectively (both pinsulin were seen at 24 months, these changes were...... maximal at month 12 and stabilized from month 12 to 24. CONCLUSIONS: Despite weight stabilization and maintenance of metabolic parameters, bone loss and deterioration in bone strength continued and were substantial in the second year. The clinical importance of these changes in terms of increased risk...

  5. Structural system identification: Structural dynamics model validation

    Energy Technology Data Exchange (ETDEWEB)

    Red-Horse, J.R.

    1997-04-01

    Structural system identification is concerned with the development of systematic procedures and tools for developing predictive analytical models based on a physical structure`s dynamic response characteristics. It is a multidisciplinary process that involves the ability (1) to define high fidelity physics-based analysis models, (2) to acquire accurate test-derived information for physical specimens using diagnostic experiments, (3) to validate the numerical simulation model by reconciling differences that inevitably exist between the analysis model and the experimental data, and (4) to quantify uncertainties in the final system models and subsequent numerical simulations. The goal of this project was to develop structural system identification techniques and software suitable for both research and production applications in code and model validation.

  6. Polyurethane foam scaffold as in vitro model for breast cancer bone metastasis.

    Science.gov (United States)

    Angeloni, Valentina; Contessi, Nicola; De Marco, Cinzia; Bertoldi, Serena; Tanzi, Maria Cristina; Daidone, Maria Grazia; Farè, Silvia

    2017-11-01

    Breast cancer (BC) represents the most incident cancer case in women (29%), with high mortality rate. Bone metastasis occurs in 20-50% cases and, despite advances in BC research, the interactions between tumor cells and the metastatic microenvironment are still poorly understood. In vitro 3D models gained great interest in cancer research, thanks to the reproducibility, the 3D spatial cues and associated low costs, compared to in vivo and 2D in vitro models. In this study, we investigated the suitability of a poly-ether-urethane (PU) foam as 3D in vitro model to study the interactions between BC tumor-initiating cells and the bone microenvironment. PU foam open porosity (>70%) appeared suitable to mimic trabecular bone structure. The PU foam showed good mechanical properties under cyclic compression (E=69-109kPa), even if lower than human trabecular bone. The scaffold supported osteoblast SAOS-2 cell line proliferation, with no cytotoxic effects. Human adipose derived stem cells (ADSC) were cultured and differentiated into osteoblast lineage on the PU foam, as shown by alizarin red staining and RT-PCR, thus offering a bone biomimetic microenvironment to the further co-culture with BC derived tumor-initiating cells (MCFS). Tumor aggregates were observed after three weeks of co-culture by e-cadherin staining and SEM; modification in CaP distribution was identified by SEM-EDX and associated to the presence of tumor cells. In conclusion, we demonstrated the suitability of the PU foam to reproduce a bone biomimetic microenvironment, useful for the co-culture of human osteoblasts/BC tumor-initiating cells and to investigate their interaction. 3D in vitro models represent an outstanding alternative in the study of tumor metastases development, compared to traditional 2D in vitro cultures, which oversimplify the 3D tissue microenvironment, and in vivo studies, affected by low reproducibility and ethical issues. Several scaffold-based 3D in vitro models have been proposed

  7. Teicoplanin-loaded borate bioactive glass implants for treating chronic bone infection in a rabbit tibia osteomyelitis model.

    Science.gov (United States)

    Zhang, Xin; Jia, Weitao; Gu, Yifei; Xiao, Wei; Liu, Xin; Wang, Deping; Zhang, Changqing; Huang, Wenhai; Rahaman, Mohamed N; Day, Delbert E; Zhou, Nai

    2010-08-01

    The treatment of chronic osteomyelitis (bone infection) remains a clinical challenge. In this work, pellets composed of a chitosan-bonded mixture of borate bioactive glass particles (glass converted to hydroxyapatite (HA) within 7 days, eventually forming a porous HA structure. Implantation of the teicoplanin-loaded pellets in a rabbit tibia osteomyelitis model resulted in the detection of teicoplanin in the blood for about 9 days. The implants converted to a bone-like HA graft, and supported the ingrowth of new bone into the tibia defects within 12 weeks of implantation. Microbiological, histological and scanning electron microscopy techniques showed that the implants provided a cure for the bone infection. The results indicate that the teicoplanin-loaded borate bioactive glass implant, combining sustained drug release with the ability to support new bone ingrowth, could provide a method for treating chronic osteomyelitis. Copyright 2010 Elsevier Ltd. All rights reserved.

  8. Comparison of the trabeculae structure of the spongy bone of the bilateral pastern bones in racehorses based on the imaging analysis of radiograms.

    Science.gov (United States)

    Dzierzecka, M; Czerwinski, E

    2010-01-01

    On the basis of a digital analysis of radiograms it was checked if, and to what extent, the extended loading of one of the sides of the body of racehorses leads to differences in the microstructure of the spongy bone of the bilateral pastern bones of the thoracic limbs. The research material consisted of radiograms of the pastern bones of the right and left thoracic limbs of racehorses. On the basis of computer image radiological analysis with the use of the "Trabecula,, programme, a quantative evaluation of the structure of the spongy bone of the pastern bones was conducted. It was noted that the differences between the right and the left pastern bones, despite extensive loading of the left thoracic limb, were not statistically significant as far as all studied parameters of the trabecula structure of the spongy bone were concerned.

  9. Mechanical regulation of bone regeneration: theories, models, and experiments.

    Science.gov (United States)

    Betts, Duncan Colin; Müller, Ralph

    2014-01-01

    How mechanical forces influence the regeneration of bone remains an open question. Their effect has been demonstrated experimentally, which has allowed mathematical theories of mechanically driven tissue differentiation to be developed. Many simulations driven by these theories have been presented, however, validation of these models has remained difficult due to the number of independent parameters considered. An overview of these theories and models is presented along with a review of experimental studies and the factors they consider. Finally limitations of current experimental data and how this influences modeling are discussed and potential solutions are proposed.

  10. Makings of a brittle bone: Unexpected lessons from a low protein diet study of a mouse OI model.

    Science.gov (United States)

    Mertz, E L; Makareeva, E; Mirigian, L S; Koon, K Y; Perosky, J E; Kozloff, K M; Leikin, S

    2016-01-01

    Glycine substitutions in type I collagen appear to cause osteogenesis imperfecta (OI) by disrupting folding of the triple helix, the structure of which requires Gly in every third position. It is less clear, however, whether the resulting bone malformations and fragility are caused by effects of intracellular accumulation of misfolded collagen on differentiation and function of osteoblasts, effects of secreted misfolded collagen on the function of bone matrix, or both. Here we describe a study originally conceived for testing how reducing intracellular accumulation of misfolded collagen would affect mice with a Gly610 to Cys substitution in the triple helical region of the α2(I) chain. To stimulate degradation of misfolded collagen by autophagy, we utilized a low protein diet. The diet had beneficial effects on osteoblast differentiation and bone matrix mineralization, but also affected bone modeling and suppressed overall animal growth. Our more important observations, however, were not related to the diet. They revealed how altered osteoblast function and deficient bone formation by each cell caused by the G610C mutation combined with increased osteoblastogenesis might make the bone more brittle, all of which are common OI features. In G610C mice, increased bone formation surface compensated for reduced mineral apposition rate, resulting in normal cortical area and thickness at the cost of altering cortical modeling process, retaining woven bone, and reducing the ability of bone to absorb energy through plastic deformation. Reduced collagen and increased mineral density in extracellular matrix of lamellar bone compounded the problem, further reducing bone toughness. The latter observations might have particularly important implications for understanding OI pathophysiology and designing more effective therapeutic interventions. Published by Elsevier B.V.

  11. A new bone surrogate model for testing interbody device subsidence.

    Science.gov (United States)

    Au, Anthony G; Aiyangar, Ameet K; Anderson, Paul A; Ploeg, Heidi-Lynn

    2011-07-15

    An in vitro biomechanical study investigating interbody device subsidence measures in synthetic vertebrae, polyurethane foam blocks, and human cadaveric vertebrae. To compare subsidence measures of bone surrogates with human vertebrae for interbody devices varying in size/placement. Bone surrogates are alternatives when human cadaveric vertebrae are unavailable. Synthetic vertebrae modeling cortices, endplates, and cancellous bone have been developed as an alternative to polyurethane foam blocks for testing interbody device subsidence. Indentors placed on the endplates of synthetic vertebrae, foam blocks, and human vertebrae were subjected to uniaxial compression. Subsidence, measured with custom-made extensometers, was evaluated for an indentor seated either centrally or peripherally on the endplate. Failure force and indentation stiffness were determined from force-displacement curves. Subsidence measures in human vertebrae varied with indentor placement: failure forces were higher and indentors subsided less with peripheral placement. Subsidence measures in foam blocks were insensitive to indentor size/placement; they were similar to human vertebrae for centrally placed but not for peripherally placed indentors. Although subsidence measures in synthetic vertebrae were sensitive to indentor size/placement, failure force and indentation stiffness were overestimated, and subsidence underestimated, for both centrally placed and peripherally placed indentors. The synthetic endplate correctly represented the human endplate geometry, and thus, failure force, stiffness, and subsidence in synthetic vertebrae were sensitive to indentor size/placement. However, the endplate was overly strong and thus synthetic vertebrae did not accurately model indentor subsidence in human cadaveric vertebrae. Foam blocks captured subsidence measures more accurately than synthetic vertebrae for centrally placed indentors, but because of their uniform density were not sufficiently robust to

  12. Involuntary wheel running improves but does not fully reverse the deterioration of bone structure of obese rats despite decreasing adiposity.

    Science.gov (United States)

    Cao, Jay J; Picklo, Matthew J

    2015-08-01

    This study investigated whether exercise or antioxidant supplementation with vitamin C and E during exercise affects bone structure and markers of bone metabolism in obese rat. Sprague-Dawley rats, 6-week old, were fed a normal-fat diet (NF, 10 % kcal as fat) and a high-fat diet (HF, 45 % with extra fat from lard) ad libitum for 14 weeks. Then, rats on the high-fat diet were assigned randomly to three treatment groups for additional 12 weeks with forced exercise: HF; HF + exercise (HF + Ex); and HF with vitamin C (0.5 g ascorbate/kg diet) and vitamin E (0.4 g α-tocopherol acetate/kg diet) supplementation + exercise (HF + Ex + VCE). At the end of the study, body weight and fat (%) were similar among NF, HF + Ex, and HF + Ex + VCE, whereas HF had greater body weight and fat (%) than other groups. Compared to NF, HF had elevated serum leptin, tartrate-resistant acid phosphatase (TRAP), and IGF-1; increased trabecular separation and structural model index; and lowered bone mineral density, trabecular connectivity density, and trabecular number in distal femur, while HF + Ex and HF + Ex + VCE had elevated serum TRAP and decreased bone volume/total volume and trabecular number of distal femurs. Compared to HF, HF + Ex and HF + Ex + VCE had decreased serum TRAP and osteocalcin and improved bone structural properties of the distal femur. These findings suggest that exercise, while decreasing body fat, does not fully protect against the negative skeletal effects of existing obesity induced by a high-fat diet. Furthermore, vitamin C and E supplementation has no additional benefits on bone structural properties during exercise.

  13. Trabecular bone structure and strength - remodelling and repair

    DEFF Research Database (Denmark)

    Mosekilde, Lis; Ebbesen, Ebbe Nils; Erikstrup, Lise Tornvig

    2000-01-01

    by the remodelling process. 5) Bone material quality will slightly change, leading to a decrease in collagen content and a relative increase in the degree of mineralisation. But, it is not known how these factors will influence the power relationship between density and strength. Nor is it known how different......The strength of the spinal trabecular bone declines by a factor of 4-5 from the age of 20 to 80 years. At the same time, the volumetric (apparent) density declines by a factor of only 2. This discrepancy can be explained by the known power relationship between density and strength; this power...... relationship is based on the fact that trabecular bone is a porous material. To date, it has not been possible to determine or quantify the influence other factors may have in determining the strength of a loadbearing trabecular network. However, it is known that with age: 1) There is a loss of connectivity...

  14. Modeling the Mechanical Consequences of Age-Related Trabecular Bone Loss by XFEM Simulation.

    Science.gov (United States)

    Fan, Ruoxun; Gong, He; Zhang, Xianbin; Liu, Jun; Jia, Zhengbin; Zhu, Dong

    2016-01-01

    The elderly are more likely to suffer from fracture because of age-related trabecular bone loss. Different bone loss locations and patterns have different effects on bone mechanical properties. Extended finite element method (XFEM) can simulate fracture process and was suited to investigate the effects of bone loss on trabecular bone. Age-related bone loss is indicated by trabecular thinning and loss and may occur at low-strain locations or other random sites. Accordingly, several ideal normal and aged trabecular bone models were created based on different bone loss locations and patterns; then, fracture processes from crack initiation to complete failure of these models were observed by XFEM; finally, the effects of different locations and patterns on trabecular bone were compared. Results indicated that bone loss occurring at low-strain locations was more detrimental to trabecular bone than that occurring at other random sites; meanwhile, the decrease in bone strength caused by trabecular loss was higher than that caused by trabecular thinning, and the effects of vertical trabecular loss on mechanical properties were more severe than horizontal trabecular loss. This study provided a numerical method to simulate trabecular bone fracture and distinguished different effects of the possible occurrence of bone loss locations and patterns on trabecular bone.

  15. Modeling the Mechanical Consequences of Age-Related Trabecular Bone Loss by XFEM Simulation

    Directory of Open Access Journals (Sweden)

    Ruoxun Fan

    2016-01-01

    Full Text Available The elderly are more likely to suffer from fracture because of age-related trabecular bone loss. Different bone loss locations and patterns have different effects on bone mechanical properties. Extended finite element method (XFEM can simulate fracture process and was suited to investigate the effects of bone loss on trabecular bone. Age-related bone loss is indicated by trabecular thinning and loss and may occur at low-strain locations or other random sites. Accordingly, several ideal normal and aged trabecular bone models were created based on different bone loss locations and patterns; then, fracture processes from crack initiation to complete failure of these models were observed by XFEM; finally, the effects of different locations and patterns on trabecular bone were compared. Results indicated that bone loss occurring at low-strain locations was more detrimental to trabecular bone than that occurring at other random sites; meanwhile, the decrease in bone strength caused by trabecular loss was higher than that caused by trabecular thinning, and the effects of vertical trabecular loss on mechanical properties were more severe than horizontal trabecular loss. This study provided a numerical method to simulate trabecular bone fracture and distinguished different effects of the possible occurrence of bone loss locations and patterns on trabecular bone.

  16. Structural disorder model

    International Nuclear Information System (INIS)

    Dixit, P.K.; Vaid, B.A.; Sharma, K.C.

    1986-01-01

    The structure disorder model, recently proposed to explain the thermodynamic properties near the transition of first order, is generalized to include the pressure-induced transitions in tetrahedrally coordinated tin and A/sup N/B/sup 8-N/ compounds (with N = 2, 3). For Sn the calculated values of the change in thermodynamic quantities during the transition are found to be closer to the experimental values. For A/sup N/B/sup 8-N/ compounds, the transition is explained in a satisfactory manner in terms of partial ionic bonds and covalent bonds. The change in compressibility near the transition is found to be in agreement with that obtained from experiments. (author)

  17. Variability of Structural and Biomechanical Parameters of Pelophylax Esculentus (Amphibia, Anura Limb Bones

    Directory of Open Access Journals (Sweden)

    Broshko Ye. O.

    2014-07-01

    Full Text Available Variability of Structural and Biomechanical Prameters of Pelophylax esculentus (Amphibia, Anura Limb Bones. Broshko Ye. O. — Structural and biomechanical parameters of Edible Frog, Pelophylax esculentus (Linnaeus, 1758, limb bones, namely, mass, linear dimensions, parameters of the shaft’s cross-sectional shape (cross-sectional area, moments of inertia, radiuses of inertia were investigated. Some coefficients were also estimated: diameters ratio (df/ds, cross-sectional index (ik, principal moments of inertia ratio (Imax/Imin.. Coefficients of variation of linear dimensions (11.9-20.0 % anrelative bone mass (22-35 % were established. Moments of inertia of various bones are more variable (CV = 41.67-56.35 % in relation to radii of inertia (CV = 9.68-14.67 %. Shaft’s cross-sectional shape is invariable in all cases. However, there is high individual variability of structural and biomechanical parameters of P. esculentus limb bones. Variability of parameters was limited by the certain range. We suggest the presence of stable norm in bone structure. Stylopodium bones have the primary biomechanical function among the elements of limb skeleton, because their parameters most clearly responsive to changes in body mass.

  18. Three-dimensional quantification of structures in trabecular bone using measures of complexity

    DEFF Research Database (Denmark)

    Marwan, Norbert; Kurths, Jürgen; Thomsen, Jesper Skovhus

    2009-01-01

    evaluate different aspects of organization and complexity of 3D structures, such as complexity of its surface or shape variability. We apply these measures to 3D data acquired by high-resolution microcomputed tomography (µCT) from human proximal tibiae and lumbar vertebrae at different stages...... of osteoporotic bone loss. The outcome is compared to the results of conventional static histomorphometry and exhibits clear relationships between the analyzed geometrical features of trabecular bone and loss of bone density, but also indicate that the measures reveal additional information about the structural...

  19. Development of a strain rate dependent material model of human cortical bone for computer-aided reconstruction of injury mechanisms.

    Science.gov (United States)

    Asgharpour, Zahra; Zioupos, Peter; Graw, Matthias; Peldschus, Steffen

    2014-03-01

    Computer-aided methods such as finite-element simulation offer a great potential in the forensic reconstruction of injury mechanisms. Numerous studies have been performed on understanding and analysing the mechanical properties of bone and the mechanism of its fracture. Determination of the mechanical properties of bones is made on the same basis used for other structural materials. The mechanical behaviour of bones is affected by the mechanical properties of the bone material, the geometry, the loading direction and mode and of course the loading rate. Strain rate dependency of mechanical properties of cortical bone has been well demonstrated in literature studies, but as many of these were performed on animal bones and at non-physiological strain rates it is questionable how these will apply in the human situations. High strain-rates dominate in a lot of forensic applications in automotive crashes and assault scenarios. There is an overwhelming need to a model which can describe the complex behaviour of bone at lower strain rates as well as higher ones. Some attempts have been made to model the viscoelastic and viscoplastic properties of the bone at high strain rates using constitutive mathematical models with little demonstrated success. The main objective of the present study is to model the rate dependent behaviour of the bones based on experimental data. An isotropic material model of human cortical bone with strain rate dependency effects is implemented using the LS-DYNA material library. We employed a human finite element model called THUMS (Total Human Model for Safety), developed by Toyota R&D Labs and the Wayne State University, USA. The finite element model of the human femur is extracted from the THUMS model. Different methods have been employed to develop a strain rate dependent material model for the femur bone. Results of one the recent experimental studies on human femur have been employed to obtain the numerical model for cortical femur. A

  20. Evaluation of osteoporotic bone structure through synchrotron radiation X-ray microfluorescence images

    Energy Technology Data Exchange (ETDEWEB)

    Lima, I. [Nuclear Engineering Program/COPPE/UFRJ, P.O. Box 68509, Av. Horacio Macedo 2030, Sala I-133, Cidade Universitaria, 21941-914 Rio de Janeiro, RJ (Brazil)], E-mail: inaya@lin.ufrj.br; Anjos, M.J. [Nuclear Engineering Program/COPPE/UFRJ, P.O. Box 68509, Av. Horacio Macedo 2030, Sala I-133, Cidade Universitaria, 21941-914 Rio de Janeiro, RJ (Brazil); Physics Institute, UERJ (Brazil); Farias, M.L.F. [University Hospital, UFRJ (Brazil); Pantaleao, T.U.; Correa da Costa, V.M. [Biophysics Institute, UFRJ (Brazil); Lopes, R.T. [Nuclear Engineering Program/COPPE/UFRJ, P.O. Box 68509, Av. Horacio Macedo 2030, Sala I-133, Cidade Universitaria, 21941-914 Rio de Janeiro, RJ (Brazil)

    2008-12-15

    The abnormal accumulation or deficiency of trace elements may theoretically impair the formation of bone and contribute to osteoporosis. In this context, the knowledge of major and trace elements is very important in order to clarify many issues regarding diseases of the bone, such as osteoporosis, that remain unresolved. Several kinds of imaging techniques can be useful to access morphology and the minerals present in osteoporotic bones. In this work, synchrotron radiation X-ray microfluorescence was used as an X-ray imaging technique to investigate bone structures. Therefore, this research aims to improve the knowledge about some aspects of bone quality. The measurements were carried out at the Brazilian Synchrotron Laboratory Light Laboratory, in Brazil. A white beam with an energy range of 4-23 keV, a 45 deg./45 deg. geometry and a capillary optics were used. It was demonstrated that bone quality can and must be evaluated not only by considering the architecture of bones but also by taking into account the concentration and the distribution of minerals. Our results showed that the elemental distributions in bone zones on a micron scale were very helpful to understand functions in those structures.

  1. Integrated materials–structural models

    DEFF Research Database (Denmark)

    Stang, Henrik; Geiker, Mette Rica

    2008-01-01

    of structural modelling and materials concepts will both operational in both identifying important research issues and in answering the ‘real’ needs of society. Integrated materials-structural models will allow synergy to develop between materials and structural research. On one side the structural modelling......Reliable service life models for load carrying structures are significant elements in the evaluation of the performance and sustainability of existing and new structures. Furthermore, reliable service life models are prerequisites for the evaluation of the sustainability of maintenance strategies...... should define a framework in which materials research results eventually should fit in and on the other side the materials research should define needs and capabilities in structural modelling. Integrated materials-structural models of a general nature are almost non-existent in the field of cement based...

  2. Using Natural Stable Calcium Isotopes to Rapidly Assess Changes in Bone Mineral Balance Using a Bed Rest Model to Induce Bone Loss

    Science.gov (United States)

    Morgan, J. L. L.; Skulan, J. L.; Gordon, G. E.; Smith, Scott M.; Romaniello, S. J.; Anbar, A. D.

    2012-01-01

    Metabolic bone diseases like osteoporosis result from the disruption of normal bone mineral balance (BMB) resulting in bone loss. During spaceflight astronauts lose substantial bone. Bed rest provides an analog to simulate some of the effects of spaceflight; including bone and calcium loss and provides the opportunity to evaluate new methods to monitor BMB in healthy individuals undergoing environmentally induced-bone loss. Previous research showed that natural variations in the Ca isotope ratio occur because bone formation depletes soft tissue of light Ca isotopes while bone resorption releases that isotopically light Ca back into soft tissue (Skulan et al, 2007). Using a bed rest model, we demonstrate that the Ca isotope ratio of urine shifts in a direction consistent with bone loss after just 7 days of bed rest, long before detectable changes in bone mineral density (BMD) occur. The Ca isotope variations tracks changes observed in urinary N-teleopeptide, a bone resorption biomarker. Bone specific alkaline phosphatase, a bone formation biomarker, is unchanged. The established relationship between Ca isotopes and BMB can be used to quantitatively translate the changes in the Ca isotope ratio to changes in BMD using a simple mathematical model. This model predicts that subjects lost 0.25 0.07% ( SD) of their bone mass from day 7 to day 30 of bed rest. Given the rapid signal observed using Ca isotope measurements and the potential to quantitatively assess bone loss; this technique is well suited to study the short-term dynamics of bone metabolism.

  3. Bioactive Hierarchical Structures for Genetic Control of Bone Morphogenesis

    Directory of Open Access Journals (Sweden)

    Pilar Sepulveda

    2002-09-01

    Full Text Available For thirty years it has been known that certain compositions of Na2O-CaO-P2O5-SiO 2 glasses will form a mechanically strong, chemical bond to bone. These materials have become known as bioactive glasses and the process of bonding is called bioactive fixation. Bioactive glasses are widely used clinically in the repair of bone defects. Recent research at the Imperial College Tissue Engineering Centre has now established that there is a genetic control of the cellular response to bioactive materials. Seven families of genes are up-regulated when primary human osteoblasts are exposed to the ionic dissolution products of bioactive glasses. The gene expression occurs very rapidly, within two days, and includes enhanced expression of cell cycle regulators. The consequence is rapid differentiation of the osteoblasts into a mature phenotype and formation of large three-dimensional bone nodules within six days in vitro. These cell culture results correlate with extensive human clinical results using the same bioactive material. The new genetic theory of bioactive materials provides a scientific foundation for molecular design of new generation of resorbable bioactive materials for tissue engineering and in situ tissue regeneration and repair. Application of this theory to the synthesis of bioactive foams for tissue engineering of bone is described.

  4. The structural changes in the bone tissue and regional lymph nodes when using bone cement

    Science.gov (United States)

    Zhukov, D. V.; Zajdman, A. M.; Prohorenko, V. M.; Ustikova, N. V.

    2017-09-01

    In orthopedics bone cement is used to replace defects. However, it is known that it possesses toxic properties, due to its composition monomer methyl methacrylate. There are some unresolved issues, in particular its local action, not investigated reaction of the immune system to respond to any fluctuations of endoecological equilibrium. All this helps to explain not only the intraoperative complications such as acute heart and lung failure, but also many deferred pathological processes, complications in the postoperative period.

  5. Bone hyperalgesia after mechanical impact stimulation: a human experimental pain model.

    Science.gov (United States)

    Finocchietti, Sara; Graven-Nielsen, Thomas; Arendt-Nielsen, Lars

    2014-12-01

    Hyperalgesia in different musculoskeletal structures including bones is a major clinical problem. An experimental bone hyperalgesia model was developed in the present study. Hyperalgesia was induced by three different weights impacted on the shinbone in 16 healthy male and female subjects. The mechanical impact pain threshold (IPT) was measured as the height from which three weights (165, 330, and 660 g) should be dropped to elicit pain at the shinbone. Temporal summation of pain to repeated impact stimuli was assessed. All these stimuli caused bone hyperalgesia. The pressure pain threshold (PPT) was assessed by a computerized pressure algometer using two different probes (1.0 and 0.5 cm(2)). All parameters were recorded before (0), 24, 72, and 96 h after the initial stimulations. The IPTs were lowest 24 h after hyperalgesia induction for all three weights and the effect lasted up to 72 h (p pain and hyperalgesia model may provide the basis for studying this fundamental mechanism of bone-related hyperalgesia and be used for profiling compounds developed for this target.

  6. Advanced methods for the quantification of trabecular bone structure and density in micro computed tomography images

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Jing

    2011-07-01

    . The implementation of structural parameters was validated with two digital models and with histological sections. The segmentation of the trabeculae was validated with a simulated {mu}CT scan of a simulated phantom and {mu}CT scans of excised mouse tibiae with different voxel sizes (9-20 {mu}m). Intra- and inter-observer analysis reproducibility was validated with five {mu}CT scans by three operators. The impact of different analysis VOIs on structural parameters was investigated. {mu}CT scans of four mouse vertebra samples were also compared with digitized histological sections. Results: With respect to calibration and TMD assessment the following results were obtained: (1) Cone beam reconstruction artifacts can be neglected. (2) To avoid an influence of the material inhomogeneity of the phantom inserts on the calibration, measured HU values inside the inserts should be averaged over their full length. (3) Epoxy resin-based plastic is not water-equivalent for voltages between 40 and 60 kV, which causes a constant offset of the TMD assessment compared to a water equivalent phantom material. (4) The quantification error caused by beam hardening was up to 5.7% at the kV settings used, which should be corrected. (5) A simultaneous scan of the bone sample and the calibration phantom is recommended. The validation confirmed that the structural parameters were correctly implemented. The simulations (simulated {mu}CT acquisition of a rods phantom) showed that the LAT segmentation gave more accurate results in particular for trabecular thickness than the global threshold method. Moreover, the LAT method is also robust to variations of spatial resolution. Decreasing the resolution by about a factor of 2 changed bone volume fraction (BV/TV) by only 3.4%. Intra and inter observer precision errors (%CVRMS) were smaller than 1.2%. The results further demonstrated that position and size of the analysis VOI had a great influence on BV/TV (up to 24.3% in 2D sections and 38.1% in {mu

  7. PRODUCT STRUCTURE DIGITAL MODEL

    Directory of Open Access Journals (Sweden)

    V.M. Sineglazov

    2005-02-01

    Full Text Available  Research results of representation of product structure made by means of CADDS5 computer-aided design (CAD system, Product Data Management Optegra (PDM system and Product Life Cycle Management Wind-chill system (PLM, are examined in this work. Analysis of structure component development and its storage in various systems is carried out. Algorithms of structure transformation required for correct representation of the structure are considered. Management analysis of electronic mockup presentation of the product structure is carried out for Windchill system.

  8. An investigation of fossil bone mineral structure with neutron scattering

    International Nuclear Information System (INIS)

    Batdehmbehrehl, G.; Chultehm, D.; Sangaa, D.

    1999-01-01

    Using the neutron diffraction method a domination of low crystal syngonic (sp. gr. P63/m) phase Ca 5 [PO 4 ] 3 (OH, F, Cl) in the fossil dinosaur bone has been established. It is shown that the neutron diffraction method has large advantages in apatite phase of any vertebrates studies and in the case of carbonate phase x-ray method it becomes to be preferable. (author)

  9. Structural dynamic modifications via models

    Indian Academy of Sciences (India)

    of structural dynamic optimization techniques. A review of structural optimization in vibratory environments is given by Rao (1989). 2. SDM techniques. SDM methods may be broadly divided into two groups. Those which employ a model of the structure and those that use dynamic test data directly. The model used by the ...

  10. The biphasic effect of triiodothyronine compared to bone resorbing effect of PTH on bone modelling of mouse long bone in vitro

    International Nuclear Information System (INIS)

    Soskolne, W.A.; Schwartz, Z.; Goldstein, M.; Ornoy, A.

    1990-01-01

    To examine the effects of T3 on fetal long bone modelling the radii and ulnae of 16 day old fetal mice were grown in vitro for two days. Their growth, mineralization, and resorption were assessed by measuring diaphyseal length, calcium and phosphorus content, hydroxyproline content, and the release of incorporated 45 Ca. The effects of T3 were compared to the effects of 1-34 PTH, a known resorbing agent, on the same system. Devitalized bones were used as a control. The results showed that T3 had a biphasic effect. At high concentrations (10(-5) M-10(-6) M) T3 inhibited the growth of the bones as indicated by their diaphyseal length and hydroxyproline content. Calcium and phosphorus content were significantly decreased while 45 Ca release was increased. Similar effects were also found after the addition of 1-34 PTH to the media. However, T3, at lower concentrations (10(-7) M-10(-9) M), stimulated the growth and calcification of the bones as indicated by an increase in diaphyseal length and the hydroxyproline, calcium, and phosphorus content. 45 Ca release was significantly decreased at these concentrations. Neither T3 nor 1-34 PTH affected devitalized bones in the same system. The results suggest that at physiological concentrations, T3 has a direct, anabolic effect on bone, which may explain its major role in the growth process of various species. At high doses, however, T3 stimulates bone resorption in a way similar to PTH

  11. Bone assemblages track animal community structure over 40 years in an African savanna ecosystem.

    Science.gov (United States)

    Western, David; Behrensmeyer, Anna K

    2009-05-22

    Reconstructing ancient communities depends on how accurately fossil assemblages retain information about living populations. We report a high level of fidelity between modern bone assemblages and living populations based on a 40-year study of the Amboseli ecosystem in southern Kenya. Relative abundance of 15 herbivorous species recorded in the bone assemblage accurately tracks the living populations through major changes in community composition and habitat over intervals as short as 5 years. The aggregated bone sample provides an accurate record of community structure time-averaged over four decades. These results lay the groundwork for integrating paleobiological and contemporary ecological studies across evolutionary and ecological time scales. Bone surveys also provide a useful method of assessing population changes and community structure for modern vertebrates.

  12. OPENING STRUCTURE OF THE BONE BASIN ON SOUTH SULAWESI IN RELATION TO PROCESS OF SEDIMENTATION

    Directory of Open Access Journals (Sweden)

    Lili Sarmili

    2017-07-01

    Full Text Available Sulawesi Island is situated on the three major plates, namely the Indo-Australian plate together with Continent Australia (Australian Craton plate moves towards the North - Northeast and crust Pacific - Philippines moves towards the West - Northwest, causing the collision with the Eurasian plate (Sunda Land which more passive or stable. The Bone basin is located between South Sulawesi and Southeast Sulawesi arms. This basin is formed by several fault system, such as, Walanae, Palukoro, West and East Bone faults and others. Several active faults are likely to be extended each other into the openings structure and characterized by the accumulation of young sediment in the Bone basin.

  13. The role of bone marrow-derived cells in bone fracture repair in a green fluorescent protein chimeric mouse model

    International Nuclear Information System (INIS)

    Taguchi, Kazuhiro; Ogawa, Rei; Migita, Makoto; Hanawa, Hideki; Ito, Hiromoto; Orimo, Hideo

    2005-01-01

    We investigated the role of bone marrow cells in bone fracture repair using green fluorescent protein (GFP) chimeric model mice. First, the chimeric model mice were created: bone marrow cells from GFP-transgenic C57BL/6 mice were injected into the tail veins of recipient wild-type C57BL/6 mice that had been irradiated with a lethal dose of 10 Gy from a cesium source. Next, bone fracture models were created from these mice: closed transverse fractures of the left femur were produced using a specially designed device. One, three, and five weeks later, fracture lesions were extirpated for histological and immunohistochemical analyses. In the specimens collected 3 and 5 weeks after operation, we confirmed calluses showing intramembranous ossification peripheral to the fracture site. The calluses consisted of GFP- and osteocalcin-positive cells at the same site, although the femur consisted of only osteocalcin-positive cells. We suggest that bone marrow cells migrated outside of the bone marrow and differentiated into osteoblasts to make up the calluses

  14. The correlation between postmenopausal osteoporosis and inflammatory periodontitis regarding bone loss in experimental models.

    Science.gov (United States)

    Kobayashi, Megumi; Matsumoto, Chiho; Hirata, Michiko; Tominari, Tsukasa; Inada, Masaki; Miyaura, Chisato

    2012-01-01

    We have invented a mouse model of periodontitis associated with alveolar bone loss induced by lipopolysaccharide. Ovariectomized (OVX) animals are widely used as a model for osteoporosis due to estrogen deficiency. To define the relationship between periodontitis and osteoporosis, we examined the influence of estrogen deficiency on the mouse alveolar bone mass. In OVX mice, bone loss was detected not only in the femur, but also in the alveolar bone, indicating that estrogen deficiency could induce resorption in alveolar bone. In experiments using a combination of osteoporosis and periodontitis models, OVX significantly enhanced the alveolar bone loss in the model of periodontitis. Therefore, postmenopausal osteoporosis may enhance the risk of periodontitis associated with inflammatory alveolar bone resorption.

  15. Immobilization and long-term recovery results in large changes in bone structure and strength but no corresponding alterations of osteocyte lacunar properties.

    Science.gov (United States)

    Bach-Gansmo, Fiona Linnea; Wittig, Nina Kølln; Brüel, Annemarie; Thomsen, Jesper Skovhus; Birkedal, Henrik

    2016-10-01

    The ability of osteocytes to demineralize the perilacunar matrix, osteocytic osteolysis, and thereby participate directly in bone metabolism, is an aspect of osteocyte biology that has received increasing attention during the last couple of years. The aim of the present work was to investigate whether osteocyte lacunar properties change during immobilization and subsequent recovery. A rat cortical bone model with negligible Haversian remodeling effects was used, with temporary immobilization of one hindlimb induced by botulinum toxin. Several complementary techniques covering multiple length scales enabled correlation of osteocyte lacunar properties to changes observed on the organ and tissue level of femoral bone. Bone structural parameters measured by μCT and mechanical properties were compared to sub-micrometer resolution SR μCT data mapping an unprecedented number (1.85 million) of osteocyte lacunae. Immobilization induced a significant reduction in aBMD, bone volume, tissue volume, and load to fracture, as well as the muscle mass of rectus femoris. During the subsequent recovery period, the bone structural and mechanical properties were only partly regained in spite of a long-term (28weeks) study period. No significant changes in osteocyte lacunar volume, density, oblateness, stretch, or orientation were detected upon immobilization or subsequent recovery. In conclusion, the bone architecture and not osteocyte lacunar properties or bone material characteristics dominate the immobilization response as well as the subsequent recovery. Copyright © 2016 Elsevier Inc. All rights reserved.

  16. Probabilistic modeling of timber structures

    DEFF Research Database (Denmark)

    Köhler, Jochen; Sørensen, John Dalsgaard; Faber, Michael Havbro

    2007-01-01

    The present paper contains a proposal for the probabilistic modeling of timber material properties. It is produced in the context of the Probabilistic Model Code (PMC) of the Joint Committee on Structural Safety (JCSS) [Joint Committee of Structural Safety. Probabilistic Model Code, Internet Publ...

  17. Effect of bone material properties on effective region in screw-bone model: an experimental and finite element study.

    Science.gov (United States)

    Liu, Shuai; Qi, Wei; Zhang, Yang; Wu, Zi-Xiang; Yan, Ya-Bo; Lei, Wei

    2014-06-21

    There have been numerous studies conducted to investigate the pullout force of pedicle screws in bone with different material properties. However, fewer studies have investigated the region of effect (RoE), stress distribution and contour pattern of the cancellous bone surrounding the pedicle screw. Screw pullout experiments were performed from two different foams and the corresponding reaction force was documented for the validation of a computational pedicle screw-foam model based on finite element (FE) methods. After validation, pullout simulations were performed on screw-bone models, with different bone material properties to model three different age groups (75 years old). At maximum pullout force, the stress distribution and average magnitude of Von Mises stress were documented in the cancellous bone along the distance beyond the outer perimeter pedicle screw. The radius and volume of the RoE were predicted based on the stress distribution. The screw pullout strengths and the load-displacement curves were comparable between the numerical simulation and experimental tests. The stress distribution of the simulated screw-bone vertebral unit showed that the radius and volume of the RoE varied with the bone material properties. The radii were 4.73 mm, 5.06 mm and 5.4 mm for bone properties of ages >75, 75 > ages >50 and ages injection cement for augmentation could be estimated based on the RoE in the treatment of osteoporosis patients to avoid leakage in spine surgery.

  18. Bone conduction responses of middle ear structures in Thiel embalmed heads

    Science.gov (United States)

    Arnold, Andreas; Stieger, Christof; Caversaccio, Marco; Kompis, Martin; Guignard, Jérémie

    2015-12-01

    Thiel-embalmed human whole-head specimens offer a promising alternative model for bone conduction (BC) studies of middle ear structures. In this work we present the Thiel model's linearity and stability over time as well as its possible use in the study of a fixed ossicle chain. Using laser Doppler vibrometry (LDV), the motion of the retroauricular skull, the promontory, the stapes footplate and the round window (RW) were measured. A bone-anchored hearing aid stimulated the ears with step sinus tones logarithmically spread between 0.1 and 10 kHz. Linearity of the model was verified using input levels in steps of 10 dBV. The stability of the Thiel model over time was examined with measurements repeated after hours and weeks. The influence of a cement-fixed stapes was assessed. The middle ear elements measured responded linearly in amplitude for the applied input levels (100, 32.6, and 10 mV). The variability of measurements for both short- (2 h) and long-term (4-16 weeks) repetitions in the same ear was lower than the interindividual difference. The fixation of the stapes induced a lowered RW displacement for frequencies near 750 Hz (-4 dB) and an increased displacement for frequencies above 1 kHz (max. +3.7 dB at 4 kHz). LDV assessment of BC-induced middle ear motion in Thiel heads can be performed with stable results. The vibratory RW response is affected by the fixation of the stapes, indicating a measurable effect of ossicle chain inertia on BC response in Thiel embalmed heads.

  19. Evaluation of bone quality in osteoporosis model mice by Raman spectroscopy

    Science.gov (United States)

    Ishimaru, Yasumitsu; Oshima, Yusuke; Imai, Yuuki; Iimura, Tadahiro; Takanezawa, Sota; Hino, Kazunori; Miura, Hiromasa

    2017-04-01

    To evaluate the bone quality in the osteoporosis, we generated sciatic nerve resection (NX) mice as an osteoporosis model and analyzed by Raman spectroscopy. Raman spectra were measured in anterior cortical surface of the proximal tibia at 5 points in each bone. After that, the samples were fixed with 70% ethanol. We then performed DXA and μCT measurement. Raman peak intensity ratios were significantly different between NX and Control. Those changes in the Raman peak intensity ratios may reflect loss of bone quality in the osteoporosis model. Raman spectroscopy is a promising technique for measuring the bone quality and bone strength.

  20. Piezoelectricity could predict sites of formation/resorption in bone remodelling and modelling.

    Science.gov (United States)

    Fernández, J R; García-Aznar, J M; Martínez, R

    2012-01-07

    We have developed a mathematical approach for modelling the piezoelectric behaviour of bone tissue in order to evaluate the electrical surface charges in bone under different mechanical conditions. This model is able to explain how bones change their curvature, where osteoblasts or osteoclasts could detect in the periosteal/endosteal surfaces the different electrical charges promoting bone formation or resorption. This mechanism also allows to understand the BMU progression in function of the electro-mechanical bone behaviour. Copyright © 2011 Elsevier Ltd. All rights reserved.

  1. Dynamic term structure models

    DEFF Research Database (Denmark)

    Andreasen, Martin Møller; Meldrum, Andrew

    pricing factors using the sequential regression approach. Our findings suggest that the two models largely provide the same in-sample fit, but loadings from ordinary and risk-adjusted Campbell-Shiller regressions are generally best matched by the shadow rate models. We also find that the shadow rate...... models perform better than the QTSMs when forecasting bond yields out of sample....

  2. Cortical Bone Stem Cell Therapy Preserves Cardiac Structure and Function After Myocardial Infarction.

    Science.gov (United States)

    Sharp, Thomas E; Schena, Giana J; Hobby, Alexander R; Starosta, Timothy; Berretta, Remus M; Wallner, Markus; Borghetti, Giulia; Gross, Polina; Yu, Daohai; Johnson, Jaslyn; Feldsott, Eric; Trappanese, Danielle M; Toib, Amir; Rabinowitz, Joseph E; George, Jon C; Kubo, Hajime; Mohsin, Sadia; Houser, Steven R

    2017-11-10

    Cortical bone stem cells (CBSCs) have been shown to reduce ventricular remodeling and improve cardiac function in a murine myocardial infarction (MI) model. These effects were superior to other stem cell types that have been used in recent early-stage clinical trials. However, CBSC efficacy has not been tested in a preclinical large animal model using approaches that could be applied to patients. To determine whether post-MI transendocardial injection of allogeneic CBSCs reduces pathological structural and functional remodeling and prevents the development of heart failure in a swine MI model. Female Göttingen swine underwent left anterior descending coronary artery occlusion, followed by reperfusion (ischemia-reperfusion MI). Animals received, in a randomized, blinded manner, 1:1 ratio, CBSCs (n=9; 2×10 7 cells total) or placebo (vehicle; n=9) through NOGA-guided transendocardial injections. 5-ethynyl-2'deoxyuridine (EdU)-a thymidine analog-containing minipumps were inserted at the time of MI induction. At 72 hours (n=8), initial injury and cell retention were assessed. At 3 months post-MI, cardiac structure and function were evaluated by serial echocardiography and terminal invasive hemodynamics. CBSCs were present in the MI border zone and proliferating at 72 hours post-MI but had no effect on initial cardiac injury or structure. At 3 months, CBSC-treated hearts had significantly reduced scar size, smaller myocytes, and increased myocyte nuclear density. Noninvasive echocardiographic measurements showed that left ventricular volumes and ejection fraction were significantly more preserved in CBSC-treated hearts, and invasive hemodynamic measurements documented improved cardiac structure and functional reserve. The number of EdU + cardiac myocytes was increased in CBSC- versus vehicle- treated animals. CBSC administration into the MI border zone reduces pathological cardiac structural and functional remodeling and improves left ventricular functional reserve

  3. Bone tissue stiffness in the mandibular condyle is dependent on the direction and density of the cancellous structure.

    NARCIS (Netherlands)

    Eijden, T.M. van; Ruijven, L.J. van; Giesen, E.B.W.

    2004-01-01

    Variation in the apparent stiffness of cancellous bone is generally ascribed to variation in cancellous structure and density, while the bone tissue stiffness is assumed to be constant. The purpose of the present study was to examine whether the bone tissue stiffness is dependent on the direction

  4. Modeling Structural Brain Connectivity

    DEFF Research Database (Denmark)

    Ambrosen, Karen Marie Sandø

    The human brain consists of a gigantic complex network of interconnected neurons. Together all these connections determine who we are, how we react and how we interpret the world. Knowledge about how the brain is connected can further our understanding of the brain’s structural organization, help...... improve diagnosis, and potentially allow better treatment of a wide range of neurological disorders. Tractography based on diffusion magnetic resonance imaging is a unique tool to estimate this “structural connectivity” of the brain non-invasively and in vivo. During the last decade, brain connectivity...... has increasingly been analyzed using graph theoretic measures adopted from network science and this characterization of the brain’s structural connectivity has been shown to be useful for the classification of populations, such as healthy and diseased subjects. The structural connectivity of the brain...

  5. Oscillating water column structural model

    Energy Technology Data Exchange (ETDEWEB)

    Copeland, Guild [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Bull, Diana L [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Jepsen, Richard Alan [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Gordon, Margaret Ellen [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2014-09-01

    An oscillating water column (OWC) wave energy converter is a structure with an opening to the ocean below the free surface, i.e. a structure with a moonpool. Two structural models for a non-axisymmetric terminator design OWC, the Backward Bent Duct Buoy (BBDB) are discussed in this report. The results of this structural model design study are intended to inform experiments and modeling underway in support of the U.S. Department of Energy (DOE) initiated Reference Model Project (RMP). A detailed design developed by Re Vision Consulting used stiffeners and girders to stabilize the structure against the hydrostatic loads experienced by a BBDB device. Additional support plates were added to this structure to account for loads arising from the mooring line attachment points. A simplified structure was designed in a modular fashion. This simplified design allows easy alterations to the buoyancy chambers and uncomplicated analysis of resulting changes in buoyancy.

  6. Engineered, axially-vascularized osteogenic grafts from human adipose-derived cells to treat avascular necrosis of bone in a rat model.

    Science.gov (United States)

    Ismail, Tarek; Osinga, Rik; Todorov, Atanas; Haumer, Alexander; Tchang, Laurent A; Epple, Christian; Allafi, Nima; Menzi, Nadia; Largo, René D; Kaempfen, Alexandre; Martin, Ivan; Schaefer, Dirk J; Scherberich, Arnaud

    2017-11-01

    Avascular necrosis of bone (AVN) leads to sclerosis and collapse of bone and joints. The standard of care, vascularized bone grafts, is limited by donor site morbidity and restricted availability. The aim of this study was to generate and test engineered, axially vascularized SVF cells-based bone substitutes in a rat model of AVN. SVF cells were isolated from lipoaspirates and cultured onto porous hydroxyapatite scaffolds within a perfusion-based bioreactor system for 5days. The resulting constructs were inserted into devitalized bone cylinders mimicking AVN-affected bone. A ligated vascular bundle was inserted upon subcutaneous implantation of constructs in nude rats. After 1 and 8weeks in vivo, bone formation and vascularization were analyzed. Newly-formed bone was found in 80% of SVF-seeded scaffolds after 8weeks but not in unseeded controls. Human ALU+cells in the bone structures evidenced a direct contribution of SVF cells to bone formation. A higher density of regenerative, M2 macrophages was observed in SVF-seeded constructs. In both experimental groups, devitalized bone was revitalized by vascularized tissue after 8 weeks. SVF cells-based osteogenic constructs revitalized fully necrotic bone in a challenging AVN rat model of clinically-relevant size. SVF cells contributed to accelerated initial vascularization, to bone formation and to recruitment of pro-regenerative endogenous cells. Avascular necrosis (AVN) of bone often requires surgical treatment with autologous bone grafts, which is surgically demanding and restricted by significant donor site morbidity and limited availability. This paper describes a de novo engineered axially-vascularized bone graft substitute and tests the potential to revitalize dead bone and provide efficient new bone formation in a rat model. The engineering of an osteogenic/vasculogenic construct of clinically-relevant size with stromal vascular fraction of human adipose, combined to an arteriovenous bundle is described. This

  7. Cells responding to surface structure of calcium phosphate ceramics for bone regeneration.

    Science.gov (United States)

    Zhang, Jingwei; Sun, Lanying; Luo, Xiaoman; Barbieri, Davide; de Bruijn, Joost D; van Blitterswijk, Clemens A; Moroni, Lorenzo; Yuan, Huipin

    2017-11-01

    Surface structure largely affects the inductive bone-forming potential of calcium phosphate (CaP) ceramics in ectopic sites and bone regeneration in critical-sized bone defects. Surface-dependent osteogenic differentiation of bone marrow stromal cells (BMSCs) partially explained the improved bone-forming ability of submicron surface structured CaP ceramics. In this study, we investigated the possible influence of surface structure on different bone-related cells, which may potentially participate in the process of improved bone formation in CaP ceramics. Besides BMSCs, the response of human brain vascular pericytes (HBVP), C2C12 (osteogenic inducible cells), MC3T3-E1 (osteogenic precursors), SV-HFO (pre-osteoblasts), MG63 (osteoblasts) and SAOS-2 (mature osteoblasts) to the surface structure was evaluated in terms of cell proliferation, osteogenic differentiation and gene expression. The cells were cultured on tricalcium phosphate (TCP) ceramics with either micron-scaled surface structure (TCP-B) or submicron-scaled surface structure (TCP-S) for up to 14 days, followed by DNA, alkaline phosphatase (ALP) and quantitative polymerase chain reaction gene assays. HBVP were not sensitive to surface structure with respect to cell proliferation and osteogenic differentiation, but had downregulated angiogenesis-related gene expression (i.e. vascular endothelial growth factor) on TCP-S. Without additional osteogenic inducing factors, submicron-scaled surface structure enhanced ALP activity and osteocalcin gene expression of human (h)BMSCs and C2C12 cells, favoured the proliferation of MC3T3-E1, MG63 and SAOS-2, and increased ALP activity of MC3T3-E1 and SV-HFO. The results herein indicate that cells with osteogenic potency (either osteogenic inducible cells or osteogenic cells) could be sensitive to surface structure and responded to osteoinductive submicron-structured CaP ceramics in cell proliferation, ALP production or osteogenic gene expression, which favour bone

  8. Infill Optimization for Additive Manufacturing-Approaching Bone-Like Porous Structures.

    Science.gov (United States)

    Wu, Jun; Aage, Niels; Westermann, Rudiger; Sigmund, Ole

    2018-02-01

    Porous structures such as trabecular bone are widely seen in nature. These structures are lightweight and exhibit strong mechanical properties. In this paper, we present a method to generate bone-like porous structures as lightweight infill for additive manufacturing. Our method builds upon and extends voxel-wise topology optimization. In particular, for the purpose of generating sparse yet stable structures distributed in the interior of a given shape, we propose upper bounds on the localized material volume in the proximity of each voxel in the design domain. We then aggregate the local per-voxel constraints by their p-norm into an equivalent global constraint, in order to facilitate an efficient optimization process. Implemented on a high-resolution topology optimization framework, our results demonstrate mechanically optimized, detailed porous structures which mimic those found in nature. We further show variants of the optimized structures subject to different design specifications, and we analyze the optimality and robustness of the obtained structures.

  9. Structural joint damage and hand bone loss in patients with rheumatoid arthritis.

    Science.gov (United States)

    Lykke, Midtbøll Ørnbjerg

    2018-03-01

    Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by pain, swelling and progressive destruction of the joints leading to loss of function and invalidity. The bone destruction in RA is characterised by two distinct features: structural joint damage and hand bone loss, and their prevention is an important treatment goal. Inhibitors of tumour necrosis factor alpha (TNF-inhibitors) have markedly improved the treatment options in RA patients who fail treatment with conventional synthetic Disease Modifying Anti Rheumatic Drugs (sDMARDS), but their effectiveness with regards to structural joint damage and hand bone loss, predictors thereof and the association with disease activity during treatment have mainly been investigated in randomized controlled trials (RCTs) with limited generalizability due to strict in- and exclusion criteria.
 The main aim of the PhD thesis was to assess and predict structural joint damage and hand bone loss in patients with early and established RA treated with sDMARDs and TNF-inhibitors. This was investigated in two cohorts: A) The "DANBIO X-ray study": an observational, nationwide, longitudinal cohort study of established RA patients treated in clinical practice who initiated TNF-inhibitor treatment after failure of sDMARDs and B) The "OPERA study": a randomized controlled trial of sDMARD-naïve patients with early RA treated with methotrexate (MTX) and intraarticular glucocorticoid injections in combination with adalimumab or placebo-adalimumab. Structural joint damage progression was assessed with the Sharp/van der Heijde radiographic method and hand bone loss was assessed with Digital X-ray Radiogrammetry. 
From the studies presented in the PhD thesis the following was concluded:
 Structural joint damage progression and hand bone loss were significantly lower during two years of TNF-inhibitor treatment compared to the previous two years of sDMARD-treatment in the DANBIO X-ray Study. The majority of patients had

  10. Substitutes of structural and non-structural autologous bone grafts in hindfoot arthrodeses and osteotomies: a systematic review.

    Science.gov (United States)

    Müller, Marc Andreas; Frank, Alexander; Briel, Matthias; Valderrabano, Victor; Vavken, Patrick; Entezari, Vahid; Mehrkens, Arne

    2013-02-07

    Structural and non-structural substitutes of autologous bone grafts are frequently used in hindfoot arthrodeses and osteotomies. However, their efficacy is unclear.The primary goal of this systematic review was to compare autologous bone grafts with structural and non-structural substitutes regarding the odds of union in hindfoot arthrodeses and osteotomies. The Medline and EMBASE and Cochrane databases were searched for relevant randomized and non-randomized prospective studies as well as retrospective comparative chart reviews. 10 studies which comprised 928 hindfoot arthrodeses and osteotomies met the inclusion criteria for this systematic review. The quality of the retrieved studies was low due to small samples sizes and confounding variables. The pooled random effect odds for union were 12.8 (95% CI 12.7 to 12.9) for structural allografts, 5.7 (95% CI 5.5 to 6.0) for cortical autologous grafts, 7.3 (95% CI 6.0 to 8.6) for cancellous allografts and 6.0 (95% CI 5.7 to 6.4) for cancellous autologous grafts. In individual studies, the odds of union in hindfoot arthrodeses achieved with cancellous autologous grafts was similar to those achieved with demineralised bone matrix or platelet derived growth factor augmented ceramic granules. Our results suggest an equivalent incorporation of structural allografts as compared to autologous grafts in hindfoot arthrodeses and osteotomies. There is a need for prospective randomized trials to further clarify the role of substitutes of autologous bone grafts in hindfoot surgery.

  11. Probabilistic Modeling of Timber Structures

    DEFF Research Database (Denmark)

    Köhler, J.D.; Sørensen, John Dalsgaard; Faber, Michael Havbro

    2005-01-01

    The present paper contains a proposal for the probabilistic modeling of timber material properties. It is produced in the context of the Probabilistic Model Code (PMC) of the Joint Committee on Structural Safety (JCSS) and of the COST action E24 'Reliability of Timber Structures'. The present pro...... probabilistic model for these basic properties is presented and possible refinements are given related to updating of the probabilistic model given new information, modeling of the spatial variation of strength properties and the duration of load effects.......The present paper contains a proposal for the probabilistic modeling of timber material properties. It is produced in the context of the Probabilistic Model Code (PMC) of the Joint Committee on Structural Safety (JCSS) and of the COST action E24 'Reliability of Timber Structures'. The present...

  12. SPAR Model Structural Efficiencies

    Energy Technology Data Exchange (ETDEWEB)

    John Schroeder; Dan Henry

    2013-04-01

    The Nuclear Regulatory Commission (NRC) and the Electric Power Research Institute (EPRI) are supporting initiatives aimed at improving the quality of probabilistic risk assessments (PRAs). Included in these initiatives are the resolution of key technical issues that are have been judged to have the most significant influence on the baseline core damage frequency of the NRC’s Standardized Plant Analysis Risk (SPAR) models and licensee PRA models. Previous work addressed issues associated with support system initiating event analysis and loss of off-site power/station blackout analysis. The key technical issues were: • Development of a standard methodology and implementation of support system initiating events • Treatment of loss of offsite power • Development of standard approach for emergency core cooling following containment failure Some of the related issues were not fully resolved. This project continues the effort to resolve outstanding issues. The work scope was intended to include substantial collaboration with EPRI; however, EPRI has had other higher priority initiatives to support. Therefore this project has addressed SPAR modeling issues. The issues addressed are • SPAR model transparency • Common cause failure modeling deficiencies and approaches • Ac and dc modeling deficiencies and approaches • Instrumentation and control system modeling deficiencies and approaches

  13. Astronaut Bone Medical Standards Derived from Finite Element (FE) Models of QCT Scans from Population Studies

    Science.gov (United States)

    Sibonga, J. D.; Feiveson, A. H.

    2014-01-01

    This work was accomplished in support of the Finite Element [FE] Strength Task Group, NASA Johnson Space Center [JSC], Houston, TX. This group was charged with the task of developing rules for using finite-element [FE] bone-strength measures to construct operating bands for bone health that are relevant to astronauts following exposure to spaceflight. FE modeling is a computational tool used by engineers to estimate the failure loads of complex structures. Recently, some engineers have used this tool to characterize the failure loads of the hip in population studies that also monitored fracture outcomes. A Directed Research Task was authorized in July, 2012 to investigate FE data from these population studies to derive these proposed standards of bone health as a function of age and gender. The proposed standards make use of an FE-based index that integrates multiple contributors to bone strength, an expanded evaluation that is critical after an astronaut is exposed to spaceflight. The current index of bone health used by NASA is the measurement of areal BMD. There was a concern voiced by a research and clinical advisory panel that the sole use of areal BMD would be insufficient to fully evaluate the effects of spaceflight on the hip. Hence, NASA may not have a full understanding of fracture risk, both during and after a mission, and may be poorly estimating in-flight countermeasure efficacy. The FE Strength Task Group - composed of principal investigators of the aforementioned population studies and of FE modelers -donated some of its population QCT data to estimate of hip bone strength by FE modeling for this specific purpose. Consequently, Human Health Countermeasures [HHC] has compiled a dataset of FE hip strengths, generated by a single FE modeling approach, from human subjects (approx.1060) with ages covering the age range of the astronauts. The dataset has been analyzed to generate a set of FE strength cutoffs for the following scenarios: a) Qualify an

  14. Animal Models and Bone Histomorphometry: Translational Research for the Human Research Program

    Science.gov (United States)

    Sibonga, Jean D.

    2010-01-01

    This slide presentation reviews the use of animal models to research and inform bone morphology, in particular relating to human research in bone loss as a result of low gravity environments. Reasons for use of animal models as tools for human research programs include: time-efficient, cost-effective, invasive measures, and predictability as some model are predictive for drug effects.

  15. The Contribution of Experimental in vivo Models to Understanding the Mechanisms of Adaptation to Mechanical Loading in Bone

    Science.gov (United States)

    Meakin, Lee B.; Price, Joanna S.; Lanyon, Lance E.

    2014-01-01

    Changing loading regimens by natural means such as exercise, with or without interference such as osteotomy, has provided useful information on the structure:function relationship in bone tissue. However, the greatest precision in defining those aspects of the overall strain environment that influence modeling and remodeling behavior has been achieved by relating quantified changes in bone architecture to quantified changes in bones’ strain environment produced by direct, controlled artificial bone loading. Jiri Hert introduced the technique of artificial loading of bones in vivo with external devices in the 1960s using an electromechanical device to load rabbit tibiae through transfixing stainless steel pins. Quantifying natural bone strains during locomotion by attaching electrical resistance strain gages to bone surfaces was introduced by Lanyon, also in the 1960s. These studies in a variety of bones in a number of species demonstrated remarkable uniformity in the peak strains and maximum strain rates experienced. Experiments combining strain gage instrumentation with artificial loading in sheep, pigs, roosters, turkeys, rats, and mice has yielded significant insight into the control of strain-related adaptive (re)modeling. This diversity of approach has been largely superseded by non-invasive transcutaneous loading in rats and mice, which is now the model of choice for many studies. Together such studies have demonstrated that over the physiological strain range, bone’s mechanically adaptive processes are responsive to dynamic but not static strains; the size and nature of the adaptive response controlling bone mass is linearly related to the peak loads encountered; the strain-related response is preferentially sensitive to high strain rates and unresponsive to static ones; is most responsive to unusual strain distributions; is maximized by remarkably few strain cycles, and that these are most effective when interrupted by short periods of rest between them

  16. Effects of low-intensity pulsed ultrasound on new trabecular bone during bone-tendon junction healing in a rabbit model: a synchrotron radiation micro-CT study.

    Directory of Open Access Journals (Sweden)

    Hongbin Lu

    Full Text Available This study was designed to evaluate the effects of low-intensity pulsed ultrasound on bone regeneration during the bone-tendon junction healing process and to explore the application of synchrotron radiation micro computed tomography in three dimensional visualization of the bone-tendon junction to evaluate the microarchitecture of new trabecular bone. Twenty four mature New Zealand rabbits underwent partial patellectomy to establish a bone-tendon junction injury model at the patella-patellar tendon complex. Animals were then divided into low-intensity pulsed ultrasound treatment (20 min/day, 7 times/week and placebo control groups, and were euthanized at week 8 and 16 postoperatively (n = 6 for each group and time point. The patella-patellar tendon specimens were harvested for radiographic, histological and synchrotron radiation micro computed tomography detection. The area of the newly formed bone in the ultrasound group was significantly greater than that of control group at postoperative week 8 and 16. The high resolution three dimensional visualization images of the bone-tendon junction were acquired by synchrotron radiation micro computed tomography. Low-intensity pulsed ultrasound treatment promoted dense and irregular woven bone formation at week 8 with greater bone volume fraction, number and thickness of new trabecular bone but with lower separation. At week 16, ultrasound group specimens contained mature lamellar bone with higher bone volume fraction and thicker trabeculae than that of control group; however, there was no significant difference in separation and number of the new trabecular bone. This study confirms that low-intensity pulsed ultrasound treatment is able to promote bone formation and remodeling of new trabecular bone during the bone-tendon junction healing process in a rabbit model, and the synchrotron radiation micro computed tomography could be applied for three dimensional visualization to quantitatively evaluate

  17. Standardized in vivo model for studying novel regenerative approaches for multitissue bone-ligament interfaces.

    Science.gov (United States)

    Padial-Molina, Miguel; Rodriguez, Juan C; Volk, Sarah L; Rios, Hector F

    2015-07-01

    The regeneration of the original structure and function of bone-ligament interfaces remains a major challenge in biomedical research. A preclinical model that maintains physiologic mechanical loads and controls for other external factors, such as microbial influence, is of great value for testing novel regenerative materials, provided that studies are performed by highly trained researchers with proper regard for animal welfare. The tooth root fenestration preclinical model is an ideal tool for hard tissue evaluation by micro-computed tomography, histological techniques and RNA analyses. The procedure starts with an extraoral incision lateral to the mandible and reflection of the masseter muscle. Superficial lateral mandibular bone is removed with standardized dimensions to expose the roots of the teeth and to eliminate periodontal ligament and cementum to expose the tooth dentin. The testing material can subsequently be applied to the defect and the flap can be repositioned and secured back in place. At specific time points, samples are collected and processed according to the subsequent analyses to be performed, which can include descriptive histology, histomorphometry, immunostaining, 3D bone imaging, electron microscopy, gene expression analyses and safety assessments.

  18. The Src family kinase inhibitor dasatinib delays pain-related behaviour and conserves bone in a rat model of cancer-induced bone pain

    DEFF Research Database (Denmark)

    Appel, Camilla Kristine; Gallego-Pedersen, Simone; Andersen, Line

    2017-01-01

    -induced bone pain, including cancer growth, osteoclastic bone degradation and nociceptive signalling. Here we investigate the role of dasatinib, an oral Src kinase family and Bcr-Abl tyrosine kinase inhibitor, in an animal model of cancer-induced bone pain. Daily administration of dasatinib (15 mg/kg, p...

  19. Assessing the Magnitude of Effect of Bone Structures on Shockwave Lithotripsy Fragmentation: Results from an In Vitro Study.

    Science.gov (United States)

    Olvera-Posada, Daniel; Alenezi, Husain; Tailly, Thomas; Dion, Marie; Denstedt, John D; Razvi, Hassan

    2016-05-01

    Several anatomic and clinical factors have been implicated in the failure rates of shock wave lithotripsy (SWL), including the attenuating effects of bony structures. We designed an in vitro model that incorporates the lumbar spine, including vertebral bodies and transverse processes along the pathway of shockwaves, to mimic the clinical scenario during SWL of upper ureteral stones. We hypothesized that the presence of bone structures in the SWL pathway significantly affects the fragmentation rate. An ordnance gelatin (OG) model was conceptualized and created to allow a pig's lumbar spine to be embedded within it. Artificial urinary calculi weighing 2 ± 0.1 g (1.2-cm diameter) were prepared using BegoStone plaster. The trial was divided into two arms: group 1 models had OG only and served as the control and group 2 models had the bone embedded in the gelatin with stone wells placed above the transverse processes. Twenty-four stones per group were subjected to SWL using the STORZ MODULITH SLX-F2 lithotripter, using the same treatment parameters. Fragments were sieved through 2- and 4-mm filters, and the fragmentation coefficients (FC) were calculated. The Mann-Whitney test was used to compare FC between the two groups. The mean fragmentation rate of group 1 was statistically significantly higher compared with group 2 using a 4-mm sieve (43% vs 0.62%, p < 0.001) and the 2-mm filter (18% vs 0.52%, p < 0.001). The presence of bone structures dramatically reduces the fragmentation rate of phantom stones using an OG in vitro model. The OG model is inexpensive and simple to use to simulate clinical situations during SWL.

  20. MATHEMATICAL MODELING OF BATCH ADSORPTION OF MANGANESE ONTO BONE CHAR

    Directory of Open Access Journals (Sweden)

    M. E. Maria

    Full Text Available Abstract The present study investigated the dynamics of batch adsorption of manganese onto bone char by using two distinct mathematical formulations: the diffusion model and the shrinking core model. Both models assumed spherical particles and adequately described the transient behavior of metal adsorption under changing operating conditions. Comparatively, the diffusion model described the manganese adsorption better at distinct particle sizes even when small particles were used (dp ≤ 0.147 mm; the shrinking core model proved to be more reliable when larger adsorbent particles were used (dp > 0.147 mm, and it described experimental data better at changing solid-liquid ratios. Manganese adsorption was favored when: (i smaller adsorbing particles were used due to the increase in the contact area and easier access to reacting sites of the char; however, such an effect proved to be limited to dp ≤ 0.147 mm, and (ii higher solid-liquid ratios were used due to the increase in the available reacting sites. External and intraparticle mass transfer dependences on particle size and solid-liquid ratio were also investigated, and results corroborated with prior investigations found in the literature.

  1. The effect of an osteolytic tumor on the three-dimensional trabecular bone morphology in an animal model

    Energy Technology Data Exchange (ETDEWEB)

    Kurth, A.A. [Orthopedic Biomechanics Lab. (OBL), Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA (United States); Dept. of Orthopaedic Surgery, University Hospital Frankfurt (Germany); Mueller, R. [Orthopedic Biomechanics Lab. (OBL), Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA (United States)

    2001-02-01

    Objective. To investigate the application of micro-computed tomography ({mu}CT) for the assessment of density differences and deterioration of three-dimensional architecture of trabecular bone in an experimental rat model for tumor- induced osteolytic defects.Design and materials. Walker carcinosarcoma 256 malignant breast cancer cells (W256) were surgically implanted into the medullary canal of the left femur of 15 4-month-old rats. Twenty-eight days after surgery all animals were killed and both femora from each rat were harvested. A total of 30 specimens (left and right femur) were scanned in a desk-top {mu}CT imaging system ({mu}CT 20, Scanco Medical) to assess densitometric and architectural parameters. For each specimen a total of 200 micro-tomographic slices with a resolution of 30 {mu}m in the distal metaphysis was taken. Bone mineral content (BMC) was analyzed for both cortical and trabecular bone (ctBMC), and for trabecular bone only (tBMC). Architectural indices (BV/TV, Tb.N, Tb.Th, Tb.Sp) according to standard definitions used in histomorphometry were calculated for trabecular bone.Results. The quantitative analysis of density parameters revealed significantly (P<0.001) lower values for ctBMC and tBMC in the tumor-bearing group (T) of 26% and 31%, respectively, compared with the contralateral control group. The quantitative analysis revealed significant (P<0.001) changes in the architectural parameters in the tumor-bearing bones compared with the contralateral control group: BV/TV was 30% lower, Tb.N and BS/TV decreased by 24% and 21%, respectively, Tb.Th. decreased by 10% and Tb.Sp. increased by 94%.Conclusions. This study demonstrates that {mu}CT is able to provide three-dimensional parameters of bone mass and trabecular structure in an animal model for tumor-induced bone loss. Recent advances in therapeutic approaches for skeletal diseases such as osteoporosis and metastatic bone disease rely on an understanding of the effects of the agents on the

  2. Local effect of zoledronic acid on new bone formation in posterolateral spinal fusion with demineralized bone matrix in a murine model.

    Science.gov (United States)

    Zwolak, Pawel; Farei-Campagna, Jan; Jentzsch, Thorsten; von Rechenberg, Brigitte; Werner, Clément M

    2018-01-01

    Posterolateral spinal fusion is a common orthopaedic surgery performed to treat degenerative and traumatic deformities of the spinal column. In posteriolateral spinal fusion, different osteoinductive demineralized bone matrix products have been previously investigated. We evaluated the effect of locally applied zoledronic acid in combination with commercially available demineralized bone matrix putty on new bone formation in posterolateral spinal fusion in a murine in vivo model. A posterolateral sacral spine fusion in murine model was used to evaluate the new bone formation. We used the sacral spine fusion model to model the clinical situation in which a bone graft or demineralized bone matrix is applied after dorsal instrumentation of the spine. In our study, group 1 received decortications only (n = 10), group 2 received decortication, and absorbable collagen sponge carrier, group 3 received decortication and absorbable collagen sponge carrier with zoledronic acid in dose 10 µg, group 4 received demineralized bone matrix putty (DBM putty) plus decortication (n = 10), and group 5 received DBM putty, decortication and locally applied zoledronic acid in dose 10 µg. Imaging was performed using MicroCT for new bone formation assessment. Also, murine spines were harvested for histopathological analysis 10 weeks after surgery. The surgery performed through midline posterior approach was reproducible. In group with decortication alone there was no new bone formation. Application of demineralized bone matrix putty alone produced new bone formation which bridged the S1-S4 laminae. Local application of zoledronic acid to demineralized bone matrix putty resulted in significant increase of new bone formation as compared to demineralized bone matrix putty group alone. A single local application of zoledronic acid with DBM putty during posterolateral fusion in sacral murine spine model increased significantly new bone formation in situ in our model. Therefore, our

  3. Multiobjective topology optimization of trabecular Bone Structure in the spine and the femur: Implications for biomimcry

    Science.gov (United States)

    Elbanna, Ahmed; Peetz, Darin

    Bone is classically considered to be a self-optimizing structure in accordance with Wolff's law. However, while the structure's ability to adapt to changing stress patterns has been well documented, whether it is fully optimal for compliance is less certain (Sigmund, 2002). Given the complexity of many biological systems, it is expected that this structure serves several purposes. We present a multi-objective topology optimization formulation for trabecular bone in the human body at two locations: the vertebrae and the femur. We account for the effect of different conflicting objectives such as maximization of stiffness, maximization of surface area, and minimization of buckling susceptibility. Our formulation enables us to determine the relative role of each of these objective in optimizing the structure. Moreover, it provides an opportunity to explore what structural features have to evolve to meet a certain objective requirements that may have been absent otherwise. For example, inclusion of stability considerations introduce numerous horizontal and diagonal members in the topology in the case of human vertebrae under vertical loading. However, the stability is found to play a lesser role in the case of the femur bone optimization. Our formulation enables investigation of bone adaptation at different locations of the body as well as under different loading and boundary conditions (e.g. healthy and diseased discs for the case of the spine). We discuss the implications of our findings on developing design rules for bio-inspired and bio-mimetic architectured materials. National Science Foundation: CMMI.

  4. Sustained-release rhBMP-2 increased bone mass and bone strength in an ovine model of postmenopausal osteoporosis.

    Science.gov (United States)

    Wu, Zi Xiang; Liu, Da; Wan, Shi Yong; Cui, Geng; Zhang, Yang; Lei, Wei

    2011-01-01

    The purpose of this study was to analyze the local treatment effects of rhBMP-2 combined with fibrin sealant (FS) on bone mineral density, microarchitectural and mechanical properties in osteoporotic ovine spine. Postmenopausal osteoporosis was induced in eight sheep through ovariectomy (OVX) and a low-calcium diet for a period of 12 months. According to the Latin square design, L3-L6 vertebrae were randomly assigned to four treatment groups: A (rhBMP-2/FS), B (rhBMP-2), C (FS) and D (blank control). All materials were injected into the assigned vertebra transpedicularly. All animals were euthanized 3 months after treatment. Bone mineral density (BMD), microarchitectural and mechanical properties were assessed. ANOVA analysis of variance was used to determine effects of rhBMP-2/FS (α = 0.05). The BMD in group A (rhBMP-2/FS) was 18.8, 30.4 and 27.9% higher than that in group B, C and D, respectively. Analysis of bone structure by micro-CT revealed higher trabecular bone volume (BV/TV), trabecular thickness (Tb.Th) and trabecular number (Tb.N) in the rhBMP-2/FS group (P osteoporosis in the spine can increase bone strength and reduce fracture risk quickly.

  5. Prenatal nutritional manipulation by in ovo enrichment influences bone structure, composition, and mechanical properties.

    Science.gov (United States)

    Yair, R; Shahar, R; Uni, Z

    2013-06-01

    The objective of this study was to examine the effect of embryonic nutritional enrichment on the development and properties of broiler leg bones (tibia and femur) from the prenatal period until maturity. To accomplish the objective, 300 eggs were divided into 2 groups: a noninjected group (control) and a group injected in ovo with a solution containing minerals, vitamins, and carbohydrates (enriched). Tibia and femur from both legs were harvested from chicks on embryonic days 19 (E19) and 21 (E21) and d 3, 7, 14, 28, and 54 posthatch (n = 8). The bones were mechanically tested (stiffness, maximal load, and work to fracture) and scanned in a micro-computed tomography (μCT) scanner to examine the structural properties of the cortical [cortical area, medullary area, cortical thickness, and maximal moment of inertia (Imax)] and trabecular (bone volume percent, trabecular thickness, and trabecular number) areas. To examine bone mineralization, bone mineral density (BMD) of the cortical area was obtained from the μCT scans, and bones were analyzed for the ash and mineral content. The results showed improved mechanical properties of the enriched group between E19 and d 3 and on d 14 (P big advantage for the young broiler. Additionally, the improved mineralization and trabecular architecture on d 28 and 54 indicate a potential long-term effect of altering embryonic nutrition.

  6. Structure of the standard model

    Energy Technology Data Exchange (ETDEWEB)

    Langacker, Paul [Pennsylvania Univ., PA (United States). Dept. of Physics

    1996-07-01

    This lecture presents the structure of the standard model, approaching the following aspects: the standard model Lagrangian, spontaneous symmetry breaking, gauge interactions, covering charged currents, quantum electrodynamics, the neutral current and gauge self-interactions, and problems with the standard model, such as gauge, fermion, Higgs and hierarchy, strong C P and graviton problems.

  7. Infill Optimization for Additive Manufacturing - Approaching Bone-like Porous Structures

    DEFF Research Database (Denmark)

    Wu, Jun; Aage, Niels; Westermann, Ruediger

    2018-01-01

    Porous structures such as trabecular bone are widely seen in nature. These structures exhibit superior mechanical properties whilst being lightweight. In this paper, we present a method to generate bone-like porous structures asl ightweight infill for additive manufacturing. Our method builds upon...... and extends voxel-wise topology optimization. In particular, for the purpose of generating sparse yet stable structures distributed in the interior of a given shape, we propose upper bounds on the localized material volume in the proximity of each voxel in the design domain. We then aggregate the local per......-voxel constraints by their p-norm into an equivalent global constraint, in order to facilitate an efficient optimization process. Implemented on a high-resolution topology optimization framework, our results demonstrate mechanically optimized, detailed porous structures which mimic those found innature. We further...

  8. The contribution of experimental in vivo models to understanding the mechanisms of adaptation to mechanical loading in bone

    Directory of Open Access Journals (Sweden)

    Lee B Meakin

    2014-10-01

    Full Text Available Changing loading regimens by natural means such as exercise, with or without interference such as osteotomy, has provided useful information on the structure:function relationship in bone tissue. However, the greatest precision in defining those aspects of the overall strain environment that influence modeling and remodeling behavior has been achieved by relating quantified changes in bone architecture to quantified changes in bones’ strain environment produced by direct, controlled artificial bone loading.Jiri Heřt introduced the technique of artificial loading of bones in vivo with external devices in the 1960s using an electromechanical device to load rabbit tibiae through transfixing stainless steel pins. Quantifying natural bone strains during locomotion by attaching electrical resistance strain gauges to bone surfaces was introduced by Lanyon, also in the 1960s. These studies in a variety of bones in a number of species demonstrated remarkable uniformity in the peak strains and maximum strain rates experienced.Experiments combining strain gauge instrumentation with artificial loading in sheep, pigs, roosters, turkeys, rats and mice has yielded significant insight into the control of strain-related adaptive (remodeling. This diversity of approach has been largely superseded by non-invasive transcutaneous loading in rats and mice which is now the model of choice for many studies. Together such studies have demonstrated that; over the physiological strain range, bone’s mechanically-adaptive processes are responsive to dynamic but not static strains; the size and nature of the adaptive response controlling bone mass is linearly related to the peak loads encountered; the strain-related response is preferentially sensitive to high strain rates and unresponsive to static ones; is most responsive to unusual strain distributions; is maximized by remarkably few strain cycles and that these are most effective when interrupted by short periods of

  9. EZH2 deletion in early mesenchyme compromises postnatal bone microarchitecture and structural integrity and accelerates remodeling.

    Science.gov (United States)

    Hemming, Sarah; Cakouros, Dimitrios; Codrington, John; Vandyke, Kate; Arthur, Agneiszka; Zannettino, Andrew; Gronthos, Stan

    2017-03-01

    In this study, we examined the functional importance of EZH2 during skeletal development and homeostasis using the conditional deletion of Ezh2 ( Ezh2 fl/fl ) in early mesenchyme with the use of a Prrx-1-cre driver mouse ( Ezh2 +/+ ). Heterozygous (Ezh2 +/- ) newborn and 4-wk-old mice exhibited increased skeletal size, growth plate size, and weight when compared to the wild-type control ( Ezh2 +/+ ), whereas homozygous deletion of Ezh2 ( Ezh2 -/- ) resulted in skeletal deformities and reduced skeletal size, growth plate size, and weight in newborn and 4-wk-old mice. Ezh2 -/- mice exhibited enhanced trabecular patterning. Osteogenic cortical and trabecular bone formation was enhanced in Ezh2 +/- and Ezh2 -/- animals. Ezh2 +/- and Ezh2 -/- mice displayed thinner cortical bone and decreased mechanical strength compared to the wild-type control. Differences in cortical bone thickness were attributed to an increased number of osteoclasts, corresponding with elevated levels of the bone turnover markers cross-linked C-telopeptide-1 and tartrate-resistant acid phosphatase, detected within serum. Moreover, Ezh2 +/- mice displayed increased osteoclastogenic potential coinciding with an upregulation of Rankl and M-csf expression by mesenchymal stem cells (MSCs). MSCs isolated from Ezh2 +/- mice also exhibited increased trilineage potential compared with wild-type bone marrow stromal/stem cells (BMSCs). Gene expression studies confirmed the upregulation of known Ezh2 target genes in Ezh2 -/- bone tissue, many of which are involved in Wnt/BMP signaling as promoters of osteogenesis and inhibitors of adipogenesis. In summary, EZH2 appears to be an important orchestrator of skeletal development, postnatal bone remodelling and BMSC fate determination in vitro and in vivo -Hemming, S., Cakouros, D., Codrington, J., Vandyke, K., Arthur, A., Zannettino, A., Gronthos, S. EZH2 deletion in early mesenchyme compromises postnatal bone microarchitecture and structural integrity and

  10. Generative models for chemical structures.

    Science.gov (United States)

    White, David; Wilson, Richard C

    2010-07-26

    We apply recently developed techniques for pattern recognition to construct a generative model for chemical structure. This approach can be viewed as ligand-based de novo design. We construct a statistical model describing the structural variations present in a set of molecules which may be sampled to generate new structurally similar examples. We prevent the possibility of generating chemically invalid molecules, according to our implicit hydrogen model, by projecting samples onto the nearest chemically valid molecule. By populating the input set with molecules that are active against a target, we show how new molecules may be generated that will likely also be active against the target.

  11. Bone disease in diabetes

    DEFF Research Database (Denmark)

    Shanbhogue, Vikram V.; Hansen, Stinus; Frost, Morten

    2017-01-01

    Type 1 and type 2 diabetes are generally accepted to be associated with increased bone fracture risk. However, the pathophysiological mechanisms of diabetic bone disease are poorly understood, and whether the associated increased skeletal fragility is a comorbidity or a complication of diabetes...... remains under debate. Although there is some indication of a direct deleterious effect of microangiopathy on bone, the evidence is open to question, and whether diabetic osteopathy can be classified as a chronic, microvascular complication of diabetes remains uncertain. Here, we review the current...... knowledge of potential contributory factors to diabetic bone disease, particularly the association between diabetic microangiopathy and bone mineral density, bone structure, and bone turnover. Additionally, we discuss and propose a pathophysiological model of the effects of diabetic microvascular disease...

  12. Simulation study of axial ultrasound transmission in heterogeneous cortical bone model

    Science.gov (United States)

    Takano, Koki; Nagatani, Yoshiki; Matsukawa, Mami

    2017-07-01

    Ultrasound propagation in a heterogeneous cortical bone was studied. Using a bovine radius, the longitudinal wave velocity distribution in the axial direction was experimentally measured in the MHz range. The bilinear interpolation and piecewise cubic Hermite interpolation methods were applied to create a three-dimensional (3D) precise velocity model of the bone using experimental data. By assuming the uniaxial anisotropy of the bone, the distributions of all elastic moduli of a 3D heterogeneous model were estimated. The elastic finite-difference time-domain method was used to simulate axial ultrasonic wave propagation. The wave propagation in the initial model was compared with that in the thinner model, where the inner part of the cortical bone model was removed. The wave front of the first arriving signal (FAS) slightly depended on the heterogeneity in each model. Owing to the decrease in bone thickness, the propagation behavior also changed and the FAS velocity clearly decreased.

  13. In Vivo Bone Formation Within Engineered Hydroxyapatite Scaffolds in a Sheep Model.

    Science.gov (United States)

    Lovati, A B; Lopa, S; Recordati, C; Talò, G; Turrisi, C; Bottagisio, M; Losa, M; Scanziani, E; Moretti, M

    2016-08-01

    Large bone defects still represent a major burden in orthopedics, requiring bone-graft implantation to promote the bone repair. Along with autografts that currently represent the gold standard for complicated fracture repair, the bone tissue engineering offers a promising alternative strategy combining bone-graft substitutes with osteoprogenitor cells able to support the bone tissue ingrowth within the implant. Hence, the optimization of cell loading and distribution within osteoconductive scaffolds is mandatory to support a successful bone formation within the scaffold pores. With this purpose, we engineered constructs by seeding and culturing autologous, osteodifferentiated bone marrow mesenchymal stem cells within hydroxyapatite (HA)-based grafts by means of a perfusion bioreactor to enhance the in vivo implant-bone osseointegration in an ovine model. Specifically, we compared the engineered constructs in two different anatomical bone sites, tibia, and femur, compared with cell-free or static cell-loaded scaffolds. After 2 and 4 months, the bone formation and the scaffold osseointegration were assessed by micro-CT and histological analyses. The results demonstrated the capability of the acellular HA-based grafts to determine an implant-bone osseointegration similar to that of statically or dynamically cultured grafts. Our study demonstrated that the tibia is characterized by a lower bone repair capability compared to femur, in which the contribution of transplanted cells is not crucial to enhance the bone-implant osseointegration. Indeed, only in tibia, the dynamic cell-loaded implants performed slightly better than the cell-free or static cell-loaded grafts, indicating that this is a valid approach to sustain the bone deposition and osseointegration in disadvantaged anatomical sites.

  14. Does PEEK/HA Enhance Bone Formation Compared With PEEK in a Sheep Cervical Fusion Model?

    Science.gov (United States)

    Walsh, William R; Pelletier, Matthew H; Bertollo, Nicky; Christou, Chris; Tan, Chris

    2016-11-01

    Polyetheretherketone (PEEK) has a wide range of clinical applications but does not directly bond to bone. Bulk incorporation of osteoconductive materials including hydroxyapatite (HA) into the PEEK matrix is a potential solution to address the formation of a fibrous tissue layer between PEEK and bone and has not been tested. Using in vivo ovine animal models, we asked: (1) Does PEEK-HA improve cortical and cancellous bone ongrowth compared with PEEK? (2) Does PEEK-HA improve bone ongrowth and fusion outcome in a more challenging functional ovine cervical fusion model? The in vivo responses of PEEK-HA Enhanced and PEEK-OPTIMA ® Natural were evaluated for bone ongrowth in the form of dowels implanted in the cancellous and cortical bone of adult sheep and examined at 4 and 12 weeks as well as interbody cervical fusion at 6, 12, and 26 weeks. The bone-implant interface was evaluated with radiographic and histologic endpoints for a qualitative assessment of direct bone contact of an intervening fibrous tissue later. Gamma-irradiated cortical allograft cages were evaluated as well. Incorporating HA into the PEEK matrix resulted in more direct bone apposition as opposed to the fibrous tissue interface with PEEK alone in the bone ongrowth as well as interbody cervical fusions. No adverse reactions were found at the implant-bone interface for either material. Radiography and histology revealed resorption and fracture of the allograft devices in vivo. Incorporating HA into PEEK provides a more favorable environment than PEEK alone for bone ongrowth. Cervical fusion was improved with PEEK-HA compared with PEEK alone as well as allograft bone interbody devices. Improving the bone-implant interface with a PEEK device by incorporating HA may improve interbody fusion results and requires further clinical studies.

  15. Mimicking Bone Healing Process to Self Repair Concrete Structure Novel Approach Using Porous Network Concrete

    NARCIS (Netherlands)

    Sangadji, S.; Schlangen, H.E.J.G.

    2013-01-01

    To repair concrete cracks in difficult or dangerous conditions such as underground structures or hazardous liquid containers, self healing mechanism is a promising alternative method. This research aims to imitate the bone self healing process by putting porous concrete internally in the concrete

  16. Combined microcomputed tomography, biomechanical and histomorphometric analysis of the peri-implant bone: a pilot study in minipig model.

    Science.gov (United States)

    Gramanzini, Matteo; Gargiulo, Sara; Zarone, Fernando; Megna, Rosario; Apicella, Antonio; Aversa, Raffaella; Salvatore, Marco; Mancini, Marcello; Sorrentino, Roberto; Brunetti, Arturo

    2016-06-01

    To present a practical approach that combines biomechanical tests, microcomputed tomography (μCT) and histomorphometry, providing quantitative results on bone structure and mechanical properties in a minipig model, in order to investigate the specific response to an innovative dental biomaterial. Titanium implants with innovative three-dimensional scaffolds were inserted in the tibias of 4 minipigs. Primary stability and osseointegration were investigated by means of insertion torque (IT) values, resonance frequency analysis (RFA), bone-to-implant contact (BIC), bone mineral density (BMD) and stereological measures of trabecular bone. A significant positive correlation was found between IT and RFA (r=0.980, p=0.0001). BMD at the implant sites was 18% less than the reference values (p=0.0156). Peri-implant Tb.Th was 50% higher, while Tb.N was 50% lower than the reference zone (pdestructive evaluation of bone architecture and mineral density, in combination with conventional analysis methods. The proposed multimodal approach allows to improve accuracy and reproducibility for peri-implant bone measurements and could support future investigations. Copyright © 2016 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  17. Temporal structures in shell models

    DEFF Research Database (Denmark)

    Okkels, F.

    2001-01-01

    The intermittent dynamics of the turbulent Gledzer, Ohkitani, and Yamada shell-model is completely characterized by a single type of burstlike structure, which moves through the shells like a front. This temporal structure is described by the dynamics of the instantaneous configuration of the shell...

  18. Modeling of Prosthetic Limb Rotation Control by Sensing Rotation of Residual Arm Bone

    Science.gov (United States)

    Kuiken, Todd A.

    2011-01-01

    We proposed a new approach to improve the control of prosthetic arm rotation in amputees. Arm rotation is sensed by implanting a small permanent magnet into the distal end of the residual bone, which produces a magnetic field. The position of the bone rotation can be derived from magnetic field distribution detected with magnetic sensors on the arm surface, and then conveyed to the prosthesis controller to manipulate the rotation of the prosthesis. Proprioception remains intact for residual limb skeletal structures; thus, this control system should be natural and easy-to-use. In this study, simulations have been conducted in an upper arm model to assess the feasibility and performance of sensing the voluntary rotation of residual humerus with an implanted magnet. A sensitivity analysis of the magnet size and arm size was presented. The influence of relative position of the magnet to the magnetic sensors, orientation of the magnet relative to the limb axis, and displacement of the magnetic sensors on the magnetic field was evaluated. The performance of shielding external magnetostatic interference was also investigated. The simulation results suggest that the direction and angle of rotation of residual humerus could be obtained by decoding the magnetic field signals with magnetic sensors built into a prosthetic socket. This pilot study provides important guidelines for developing a practical interface between the residual bone rotation and the prosthesis for control of prosthetic rotation. PMID:18713682

  19. A Versatile Protocol for Studying Calvarial Bone Defect Healing in a Mouse Model.

    Science.gov (United States)

    Samsonraj, Rebekah M; Dudakovic, Amel; Zan, Pengfei; Pichurin, Oksana; Cool, Simon M; van Wijnen, Andre J

    2017-11-01

    Animal models are vital tools for the preclinical development and testing of therapies aimed at providing solutions for several musculoskeletal disorders. For bone tissue engineering strategies addressing nonunion conditions, rodent models are particularly useful for studying bone healing in a controlled environment. The mouse calvarial defect model permits evaluation of drug, growth factor, or cell transplantation efficacy, together with offering the benefit of utilizing genetic models to study intramembranous bone formation within defect sites. In this study, we describe a detailed methodology for creating calvarial defects in mouse and present our results on bone morphogenetic protein-2-loaded fibrin scaffolds, thus advocating the utility of this functional orthotopic mouse model for the evaluation of therapeutic interventions (such as growth factors or cells) intended for successful bone regeneration therapies.

  20. Effects of electric and magnetic loadings on bone surface remodeling: a model modification and simulation.

    Science.gov (United States)

    Kazerooni, Anahita Fathi; Rabbani, Mohsen; Yazdchi, Mohammadreza; Kasiri, Saeid; Rad, Hamidreza Saligheh

    2011-06-01

    This paper presents a new modification to the previous model of bone surface remodeling under electric and magnetic loadings. For this study, the thermo-electro-magneto-elastic model of bone surface remodeling is used. This model is modified by considering an important phenomenon occurring in living bone through its adaptation to external loadings called desensitization. In fact, bone cells lose their responsiveness and sensitivity to long-term external loadings, i.e., they become desensitized. Therefore, bone cells need a recovery period, during which they become resensitized. In this work, this phenomenon is considered in the original model. The effects of various electric and magnetic loading conditions, including various frequencies, waveforms and pulse duty cycles, are explored on the modified model and compared to the original model. The modified model is also searched for the optimal frequency and duty cycle, to obtain the best bone growth response under electromagnetic fields. The results of this paper show that the modified model is consistent with experimental observations. In addition, it is indicated that this modified model in contrast to the original model, is sensitive to frequency. It is shown that the optimal frequency of loading for the modified model is 1 Hertz (Hz), and the pulse duty cycles up to 50% are sufficient for bone remodeling to reach its maximum value.

  1. Structural degradation of acrylic bone cements due to in vivo and simulated aging.

    Science.gov (United States)

    Hughes, Kerry F; Ries, Michael D; Pruitt, Lisa A

    2003-05-01

    Acrylic bone cement is the primary load-bearing material used for the attachment of orthopedic devices to adjoining bone. Degradation of acrylic-based cements in vivo results in a loss of structural integrity of the bone-cement-prosthesis interface and limits the longevity of cemented orthopedic implants. The purpose of this study is to investigate the effect of in vivo aging on the structure of the acrylic bone cement and to develop an in vitro artificial aging protocol that mimics the observed degradation. Three sets of retrievals are examined in this study: Palacos brand cement retrieved from hip replacements, and Simplex brand cement retrieved from both hip and knee replacement surgeries. In vitro aging is performed using oxidative and acidic environments on three acrylic-based cements: Palacos, Simplex, and CORE. Gel permeation chromatography (GPC) and Fourier transform infrared spectroscopy (FTIR) are used to examine the evolution of molecular weight and chemical species within the acrylic cements due to both in vivo and simulated aging. GPC analysis indicates that molecular weight is degraded in the hip retrievals but not in the knee retrievals. Artificial aging in an oxidative environment best reproduces this degradation mechanism. FTIR analysis indicates that there exists a chemical evolution within the cement due to in vivo and in vitro aging. These findings are consistent with scission-based degradation schemes in the cement. Based on the results of this study, a pathway for structural degradation of acrylic bone cement is proposed. The findings from this investigation have broad applicability to acrylic-based cements and may provide guidance for the development of new bone cements that resist degradation in the body. Copyright 2003 Wiley Periodicals, Inc.

  2. Effects of bone substitute architecture and surface properties on cell response, angiogenesis, and structure of new bone

    NARCIS (Netherlands)

    Bobbert, F.S.L.; Zadpoor, A.A.

    2017-01-01

    The success of bone substitutes used to repair bone defects such as critical sized defects depends on the architecture of the porous biomaterial. The architectural parameters and surface properties affect cell seeding efficiency, cell response, angiogenesis, and eventually bone formation. The

  3. Bone structure changes in iliac crest grafts combined with implants

    NARCIS (Netherlands)

    Verhoeven, Jan Willem; Ruijter, Jan M.; Koole, Ronald; de Putter, Cornelis; Cune, Marco S.

    2010-01-01

    Remodeling of onlay grafts combined with implants to the mandible results in predictable changes in the graft's radiographic density. We studied the relationship between changes in radiographic density and trabecular structure during the first year after onlay grafting with simultaneous implant

  4. Microfluidic vascularized bone tissue model with hydroxyapatite-incorporated extracellular matrix.

    Science.gov (United States)

    Jusoh, Norhana; Oh, Soojung; Kim, Sudong; Kim, Jangho; Jeon, Noo Li

    2015-10-21

    Current in vitro systems mimicking bone tissues fail to fully integrate the three-dimensional (3D) microvasculature and bone tissue microenvironments, decreasing their similarity to in vivo conditions. Here, we propose 3D microvascular networks in a hydroxyapatite (HA)-incorporated extracellular matrix (ECM) for designing and manipulating a vascularized bone tissue model in a microfluidic device. Incorporation of HA of various concentrations resulted in ECM with varying mechanical properties. Sprouting angiogenesis was affected by mechanically modulated HA-extracellular matrix interactions, generating a model of vascularized bone microenvironment. Using this platform, we observed that hydroxyapatite enhanced angiogenic properties such as sprout length, sprouting speed, sprout number, and lumen diameter. This new platform integrates fibrin ECM with the synthetic bone mineral HA to provide in vivo-like microenvironments for bone vessel sprouting.

  5. Ti-6Al-4V triply periodic minimal surface structures for bone implants fabricated via selective laser melting.

    Science.gov (United States)

    Yan, Chunze; Hao, Liang; Hussein, Ahmed; Young, Philippe

    2015-11-01

    Triply periodic minimal surface (TPMS) structures have already been shown to be a versatile source of biomorphic scaffold designs. Therefore, in this work, Ti-6Al-4V Gyroid and Diamond TPMS lattices having an interconnected high porosity of 80-95% and pore sizes in the range of 560-1600 μm and 480-1450 μm respectively were manufactured by selective laser melting (SLM) for bone implants. The manufacturability, microstructure and mechanical properties of the Ti-6Al-4V TPMS lattices were evaluated. Comparison between 3D micro-CT reconstructed models and original CAD models of the Ti-6Al-4V TPMS lattices shows excellent reproduction of the designs. The as-built Ti-6Al-4V struts exhibit the microstructure of columnar grains filled with very fine and orthogonally oriented α' martensitic laths with the width of 100-300 nm and have the microhardness of 4.01 ± 0.34 GPa. After heat treatment at 680°C for 4h, the α' martensite was converted to a mixture of α and β, in which the α phase being the dominant fraction is present as fine laths with the width of 500-800 nm and separated by a small amount of narrow, interphase regions of dark β phase. Also, the microhardness is decreased to 3.71 ± 0.35 GPa due to the coarsening of the microstructure. The 80-95% porosity TPMS lattices exhibit a comparable porosity with trabecular bone, and the modulus is in the range of 0.12-1.25 GPa and thus can be adjusted to the modulus of trabecular bone. At the same range of porosity of 5-10%, the moduli of cortical bone and of the Ti-6Al-4V TPMS lattices are in a similar range. Therefore, the modulus and porosity of Ti-6Al-4V TPMS lattices can be tailored to the levels of human bones and thus reduce or avoid "stress shielding" and increase longevity of implants. Due to the biomorphic designs, and high interconnected porosity and stiffness comparable to human bones, SLM-made Ti-6Al-4V TPMS lattices can be a promising material for load bearing bone implants. Copyright © 2015 Elsevier

  6. Stereological measures of trabecular bone structure: comparison of 3D micro computed tomography with 2D histological sections in human proximal tibial bone biopsies

    DEFF Research Database (Denmark)

    Thomsen, Jesper Skovhus; Laib, A.; Koller, B.

    2005-01-01

    Stereology applied on histological sections is the 'gold standard' for obtaining quantitative information on cancellous bone structure. Recent advances in micro computed tomography (microCT) have made it possible to acquire three-dimensional (3D) data non-destructively. However, before the 3D...... methods can be used as a substitute for the current 'gold standard' they have to be verified against the existing standard. The aim of this study was to compare bone structural measures obtained from 3D microCT data sets with those obtained by stereology performed on conventional histological sections...... and analysed with a computerized method. Trabecular bone volume (BV/TV) and connectivity density (CD) were estimated in both modalities, whereas trabecular bone pattern factor (TBPf) was estimated on the histological sections only. Trabecular thickness (Tb.Th), number (Tb.N) and separation (Tb...

  7. Muscle cross-sectional area and structural bone strength share genetic and environmental effects in older women.

    Science.gov (United States)

    Mikkola, Tuija M; Sipilä, Sarianna; Rantanen, Taina; Sievänen, Harri; Suominen, Harri; Tiainen, Kristina; Kaprio, Jaakko; Koskenvuo, Markku; Kauppinen, Markku; Heinonen, Ari

    2009-02-01

    The purpose of this study was to estimate to what extent muscle cross-sectional area of the lower leg (mCSA) and tibial structural strength are influenced by common and trait-specific genetic and environmental factors. pQCT scans were obtained from both members of 102 monozygotic (MZ) and 113 dizygotic (DZ) 63- to 76-yr-old female twin pairs to estimate the mCSA of the lower leg, structural bending strength of the tibial shaft (BSIbend), and compressive strength of the distal tibia (BSIcomp). Quantitative genetic models were used to decompose the phenotypic variances into common and trait-specific additive genetic (A), shared environmental (C), and individual environmental (E) effects. The age-adjusted trivariate independent pathway model showed that the total relative contributions of A, C, and E were, respectively, 75%, 0%, and 25% for mCSA, 55%, 20%, and 25% for BSIbend, and 40%, 37%, and 23% for BSIcomp. In addition, the model showed that all three traits shared genetic and individual environmental factors. BSIbend and BSIcomp had common shared environmental factors and were also influenced by trait-specific genetic factors. In conclusion, the association between muscle cross-sectional area and structural bone strength has its origins in both genetic and environmental effects in older women. These results suggest that in older women the same genetic and environmental factors may predispose to or, conversely, protect from both sarcopenia and bone fragility.

  8. TH-C-18A-02: Machine Learning and STAPLE Based Simultaneous Longitudinal Segmentation of Bone and Marrow Structures From Dual Energy CT

    International Nuclear Information System (INIS)

    Fehr, D; Schmidtlein, C; Hwang, S; Deasy, J; Veeraraghavan, H

    2014-01-01

    Purpose: To develop a fully-automatic longitudinal bone and marrow segmentation method in the pelvic region from dual energy computed tomography (DECT). Methods: We developed a two-step automatic bone and marrow segmentation method for simultaneous longitudinal evaluation of patients with metastatic bone disease using dual energy CT (DECT). Our approach transforms the DECT images into a multi-material decomposition (MMD) model that represents the voxels as a mixture of multiple materials. A support vector machine (SVM) was trained using a single scan. In the first step of the longitudinal segmentation the trained SVM model detects bone and marrow structures on all available longitudinal scans. Segmentation is further refined through active contour segmentation. In the second step, the segmentations from the individual scans are merged by employing the simultaneous truth and performance level estimation (STAPLE) algorithm. The scans are registered using affine and deformable registration. We found that our approach improves the segmentation in all the scans under reliable registration performance between the same scans. Improving registration was not under the scope of this work. Results: We applied our approach to segment bone and marrow in DECT scans in the pelvic regions for multiple patients. Each patient had three to five follow up scans. All the patients in the analysis had artificial metal prostheses which introduced challenges for the registration. Our algorithm achieved reasonable accurate segmentation despite the presence of metal artifacts and high-density oral contrast in neighboring structures. Our approach obtained an overall segmentation accuracy of 80% using DICE metric. Conclusion: We developed a two-step automatic longitudinal segmentation technique for bone and marrow region structures in the pelvic areas from dual energy CT. Our approach achieves robust segmentation despite the presence of confounding structures with similar intensities as the

  9. Early Subchondral Bone Loss at Arthritis Onset Predicted Late Arthritis Severity in a Rat Arthritis Model.

    Science.gov (United States)

    Courbon, Guillaume; Cleret, Damien; Linossier, Marie-Thérèse; Vico, Laurence; Marotte, Hubert

    2017-06-01

    Synovitis is usually observed before loss of articular function in rheumatoid arthritis (RA). In addition to the synovium and according to the "Inside-Outside" theory, bone compartment is also involved in RA pathogenesis. Then, we investigated time dependent articular bone loss and prediction of early bone loss to late arthritis severity on the rat adjuvant-induced arthritis (AIA) model. Lewis female rats were longitudinally monitored from arthritis induction (day 0), with early (day 10) and late (day 17) steps. Trabecular and cortical microarchitecture parameters of four ankle bones were assessed by microcomputed tomography. Gene expression was determined at sacrifice. Arthritis occurred at day 10 in AIA rats. At this time, bone erosions were detected on four ankle bones, with cortical porosity increase (+67%) and trabecular alterations including bone volume fraction (BV/TV: -13%), and trabecular thickness decrease. Navicular bone assessment was the most reproducible and sensitive. Furthermore, strong correlations were observed between bone alterations at day 10 and arthritis severity or bone loss at day 17, including predictability of day 10 BV/TV to day 17 articular index (R 2  = 0.76). Finally, gene expression at day 17 confirmed massive osteoclast activation and interestingly provided insights on strong activation of bone formation inhibitor markers at the joint level. In rat AIA, bone loss was already observed at synovitis onset and was predicted late arthritis severity. Our results reinforced the key role of subchondral bone in arthritis pathogenesis, in favour to the "Inside-Outside" theory. Mechanisms of bone loss in rat AIA involved resorption activation and formation inhibition changes. J. Cell. Physiol. 232: 1318-1325, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  10. Development of Cranial Bone Surrogate Structures Using Stereolithographic Additive Manufacturing

    Science.gov (United States)

    2017-09-29

    human cranium. Surrogate structures were designed to replicate the solid volume and thickness of the diploë and inner and outer tables typical of human...by ANSI Std. Z39.18 Approved for public release; distribution is unlimited. iii Contents List of Figures iv List of Tables iv Preface v...polymer layer deposition relative to dumbbell geometry for edge and flat specimen types ........................................................... 9

  11. Osteoporotic rat models for evaluation of osseointegration of bone implants

    NARCIS (Netherlands)

    Alghamdi, H.S.A.; Beucken, J.J.J.P van den; Jansen, J.A.

    2014-01-01

    Osseointegration of dental and orthopedic bone implants is the important process that leads to mechanical fixation of implants and warrants implant functionality. In view of increasing numbers of osteoporotic patients, bone implant surface optimization strategies with instructive and drug-loading

  12. High Insulin Levels in KK-Ay Diabetic Mice Cause Increased Cortical Bone Mass and Impaired Trabecular Micro-Structure

    Directory of Open Access Journals (Sweden)

    Cen Fu

    2015-04-01

    Full Text Available Type 2 diabetes mellitus (T2DM is a chronic disease characterized by hyperglycemia, hyperinsulinemia and complications, including obesity and osteoporosis. Rodents have been widely used to model human T2DM and investigate its effect on the skeleton. We aimed to investigate skeletal alterations in Yellow Kuo Kondo (KK-Ay diabetic mice displaying high insulin and glucose levels. Bone mineral density (BMD, micro-architecture and bone metabolism-related genes were analyzed. The total femoral areal BMD (aBMD, cortical volumetric BMD (vBMD and thickness were significantly increased in KK-Ay mice, while the trabecular vBMD and mineralized bone volume/tissue volume (BV/TV, trabecular thickness and number were decreased compared to C57BL mice. The expression of both osteoblast-related genes, such as osteocalcin (OC, bone sialoprotein, Type I Collagen, osteonectin, RUNX2 and OSX, and osteoclast-related genes, such as TRAP and TCIRG, were up-regulated in KK-Ay mice. Correlation analyses showed that serum insulin levels were positively associated with aBMD, cortical vBMD and thickness and negatively associated with trabecular vBMD and micro-architecture. In addition, serum insulin levels were positively related to osteoblast-related and osteoclast-related gene expression. Our data suggest that high insulin levels in KK-Ay diabetic mice may increase cortical bone mass and impair trabecular micro-structure by up-regulating osteoblast-and osteoclast-related gene expression.

  13. Alterations in archaeological bones thermally treated: structure and morphology; Alteraciones en huesos arqueologicos termicamente tratados: estructura y morfologia

    Energy Technology Data Exchange (ETDEWEB)

    Pijoan, C.M.; Mansilla, J.; Leboreiro, I. [Direccion de Antropologia Fisica, INAH, Gandhi s/n, Polanco, 11560 Mexico D. F. (Mexico); Lara, V.H. [Universidad Autonoma Metropolitana-lztapalapa, Michoacan esquina La Purisima, Apdo.Postal 55-534, Mexico D. F. (Mexico); Bosch, P. [Instituto de Investigaciones en Materiales, UNAM, Circuito Exterior, Ciudad Universitaria, 04510 Mexico D. F. (Mexico)

    2004-07-01

    Archaeological bones found close to Mexico city (Tlatelcomila) have been characterized by X-ray Diffraction, Small Angle X-ray Spectroscopy and Scanning Electron Microscopy. These techniques, which are not conventionally used in archaeological research, provided useful information. The boiled bones were clearly distinguished from grilled bones. The degree of deterioration of the bone structure was quantified through parameters such as gyration radius or fractal dimension. The morphology followed the structural modifications and changes resulting from thermic exposure. (Author) 23 refs., 1 tab., 2 figs.

  14. The finite element method for micro-scale modeling of ultrasound propagation in cancellous bone.

    Science.gov (United States)

    Vafaeian, B; El-Rich, M; El-Bialy, T; Adeeb, S

    2014-08-01

    Quantitative ultrasound for bone assessment is based on the correlations between ultrasonic parameters and the properties (mechanical and physical) of cancellous bone. To elucidate the correlations, understanding the physics of ultrasound in cancellous bone is demanded. Micro-scale modeling of ultrasound propagation in cancellous bone using the finite-difference time-domain (FDTD) method has been so far utilized as one of the approaches in this regard. However, the FDTD method accompanies two disadvantages: staircase sampling of cancellous bone by finite difference grids leads to generation of wave artifacts at the solid-fluid interface inside the bone; additionally, this method cannot explicitly satisfy the needed perfect-slip conditions at the interface. To overcome these disadvantages, the finite element method (FEM) is proposed in this study. Three-dimensional finite element models of six water-saturated cancellous bone samples with different bone volume were created. The values of speed of sound (SOS) and broadband ultrasound attenuation (BUA) were calculated through the finite element simulations of ultrasound propagation in each sample. Comparing the results with other experimental and simulation studies demonstrated the capabilities of the FEM for micro-scale modeling of ultrasound in water-saturated cancellous bone. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Biomechanical characterization of an osteoporotic artificial bone model for the distal femur.

    Science.gov (United States)

    Wähnert, Dirk; Hoffmeier, Konrad L; Klos, Kajetan; Stolarczyk, Yves; Fröber, Rosemarie; Hofmann, Gunther O; Mückley, Thomas

    2012-01-01

    The treatment of osteoporotic distal femur fractures is still an unsolved problem of trauma surgery. The poor bone stock often leads to secondary loss of reduction and implant failure. Therefore, the development of new implants and their biomechanical testing is essential. In a previous study, we developed and initially characterized an artificial osteoporotic bone model of the distal femur. This follow-up study was performed to characterize this model in a biomechanical comparison. We investigated two different artificial bones: five foam cortical shell (Sawbones) and 10 custom-made artificial femoral condyles. Additionally, eight human femora were used for comparison. For biomechanical testing, two intramedullary nails (distal femur nail (DFN) and supracondylar nail (SCN)) were cyclically axial loaded in an AO 33 C2 unstable distal femoral fracture model. In our testing, the artificial bone showed a decrease in the axial stiffness of 27% for the SCN and 28% for the DFN compared to the human results. Also the number of cycles for a deformation of 2.5 mm was reduced by 55% (SCN) and 62% (DFN). This decrease was homogenous and caused by the relative high bone mineral density of the human specimen used. The modes of failure showed no difference between the artificial and human bones. Our customized artificial bone provides suitable results. In relation to the human bones classified as mildly osteoporotic, we assume that the biomechanical properties match to serve as an osteoporotic bone. Yet, we suggest to check transferability of the results with human material.

  16. Histomorphometric evaluation of bone healing in rabbit fibular osteotomy model without fixation

    Directory of Open Access Journals (Sweden)

    Paixão Fabio B

    2008-01-01

    Full Text Available Abstract Background Animal models of fracture consolidation are fundamental for the understanding of the biological process of bone repair in humans, but histological studies are rare and provide only qualitative results. The objective of this article is to present the histomorphometric study of the bone healing process using an experimental model of osteotomy in rabbit fibula without interference of synthesis material. Methods Fifteen rabbits were submitted to fibular osteotomy without any fixation device. Groups of five animals were submitted to pharmacological euthanasia during a period of one (group A, two (group B and four weeks (group C after osteotomy. Histomorphometric evaluation was performed in the histological sections. Results During week one there was intense cellularity (67/field, a large amount of woven bone (75.7% and a small amount of lamellar bone (7.65%. At two weeks there was a decrease in woven bone (41.59% and an increase in lamellar bone (15.16%. At four weeks there was a decrease of cellularity (19.17/field and lamellar bone (55.56% exceeded the quantity of woven bone (31.68%. Conclusion Histomorphometric (quantitative evaluation of the present study was shown to be compatible with bone healing achieved in qualitative experimental models that have been commended in the literature.

  17. Effects of different varieties of Maca (Lepidium meyenii) on bone structure in ovariectomized rats.

    Science.gov (United States)

    Gonzales, Carla; Cárdenas-Valencia, Isaias; Leiva-Revilla, Johanna; Anza-Ramirez, Cecilia; Rubio, Julio; Gonzales, Gustavo F

    2010-01-01

    This study was designed to determine the effect of different varieties of maca (Lepidium meyenii) on bone structure in ovariectomized (OVX) rats. 36 female rats were randomly divided into 6 groups: sham and OVX rats treated with vehicle, estradiol (40 microg/kg), black, yellow or red maca (63 mg/ml) for 4 weeks. At the end of the treatment, uterine weight, femoral bone and lumbar vertebra histomorphology were assessed. Ovariectomy reduced weight, diameter and width of the femoral bone. Estradiol, black and red maca treatment reduced the effect of ovariectomy on these variables. Histological analyses revealed that estradiol, black and red maca treatments reversed the effect of ovariectomy by increasing the trabecular bone area in the second lumbar vertebra. Uterine weight was reduced in OVX rats, and estradiol but neither black nor red maca increased uterine weight. Red and black maca have protective effects on bone architecture in OVX rats without showing estrogenic effects on uterine weight. 2010 S. Karger AG, Basel.

  18. Electrospun PCL/gelatin composite nanofiber structures for effective guided bone regeneration membranes.

    Science.gov (United States)

    Ren, Ke; Wang, Yi; Sun, Tao; Yue, Wen; Zhang, Hongyu

    2017-09-01

    Guided bone regeneration (GBR) membranes have been proved of great benefit for bone tissue engineering due to the improvement of cell attachment and proliferation. To develop GBR membranes with better biocompatibility and more proper degradation ability, here we fabricated polycaprolactone (PCL, polymer)/gelatin (protein) hybrid nanofibrous GBR membranes via electrospinning, followed by crosslinking with genipin. Acetic acid (HAc) was utilized to resolve the phase separation of PCL and gelatin, therefore homogeneous PCL/gelatin hybrid nanofibers with different ratios were successfully prepared. FTIR, XPS, TGA, DSC results proved that the proportion of PCL and gelatin in the as-spun nanofiber membranes could be simply adjusted by changing the weight ratio of PCL and gelatin in the spinning solution. SEM and AFM images demonstrated that all the nanofibers possessed uniform and smooth structures both in two dimension (2D) and three dimension (3D). The mechanical tests showed that these nanofibers exhibited appropriate tensile and strength properties, which were suitable for bone tissue engineering. CCK-8 and SEM images revealed that all the membranes were biocompatible to MC3T3-e1 cells. In addition, the in vitro osteogenesis characterizations, alizarin red in normal medium and osteogenesis medium, indicated that the nanofibers could promote bone formation. Therefore, all these results could suggest that our design of electrospun polymer/protein nanofiber membranes was effective for guided bone regeneration. Copyright © 2017. Published by Elsevier B.V.

  19. Life-History Traits of the Miocene Hipparion concudense (Spain) Inferred from Bone Histological Structure

    Science.gov (United States)

    Martinez-Maza, Cayetana; Alberdi, Maria Teresa; Nieto-Diaz, Manuel; Prado, José Luis

    2014-01-01

    Histological analyses of fossil bones have provided clues on the growth patterns and life history traits of several extinct vertebrates that would be unavailable for classical morphological studies. We analyzed the bone histology of Hipparion to infer features of its life history traits and growth pattern. Microscope analysis of thin sections of a large sample of humeri, femora, tibiae and metapodials of Hipparion concudense from the upper Miocene site of Los Valles de Fuentidueña (Segovia, Spain) has shown that the number of growth marks is similar among the different limb bones, suggesting that equivalent skeletochronological inferences for this Hipparion population might be achieved by means of any of the elements studied. Considering their abundance, we conducted a skeletechronological study based on the large sample of third metapodials from Los Valles de Fuentidueña together with another large sample from the Upper Miocene locality of Concud (Teruel, Spain). The data obtained enabled us to distinguish four age groups in both samples and to determine that Hipparion concudense tended to reach skeletal maturity during its third year of life. Integration of bone microstructure and skeletochronological data allowed us to identify ontogenetic changes in bone structure and growth rate and to distinguish three histologic ontogenetic stages corresponding to immature, subadult and adult individuals. Data on secondary osteon density revealed an increase in bone remodeling throughout the ontogenetic stages and a lesser degree thereof in the Concud population, which indicates different biomechanical stresses in the two populations, likely due to environmental differences. Several individuals showed atypical growth patterns in the Concud sample, which may also reflect environmental differences between the two localities. Finally, classification of the specimens’ age within groups enabled us to characterize the age structure of both samples, which is typical of

  20. Life-history traits of the Miocene Hipparion concudense (Spain inferred from bone histological structure.

    Directory of Open Access Journals (Sweden)

    Cayetana Martinez-Maza

    Full Text Available Histological analyses of fossil bones have provided clues on the growth patterns and life history traits of several extinct vertebrates that would be unavailable for classical morphological studies. We analyzed the bone histology of Hipparion to infer features of its life history traits and growth pattern. Microscope analysis of thin sections of a large sample of humeri, femora, tibiae and metapodials of Hipparion concudense from the upper Miocene site of Los Valles de Fuentidueña (Segovia, Spain has shown that the number of growth marks is similar among the different limb bones, suggesting that equivalent skeletochronological inferences for this Hipparion population might be achieved by means of any of the elements studied. Considering their abundance, we conducted a skeletechronological study based on the large sample of third metapodials from Los Valles de Fuentidueña together with another large sample from the Upper Miocene locality of Concud (Teruel, Spain. The data obtained enabled us to distinguish four age groups in both samples and to determine that Hipparion concudense tended to reach skeletal maturity during its third year of life. Integration of bone microstructure and skeletochronological data allowed us to identify ontogenetic changes in bone structure and growth rate and to distinguish three histologic ontogenetic stages corresponding to immature, subadult and adult individuals. Data on secondary osteon density revealed an increase in bone remodeling throughout the ontogenetic stages and a lesser degree thereof in the Concud population, which indicates different biomechanical stresses in the two populations, likely due to environmental differences. Several individuals showed atypical growth patterns in the Concud sample, which may also reflect environmental differences between the two localities. Finally, classification of the specimens' age within groups enabled us to characterize the age structure of both samples, which is

  1. Effect of vibration on osteoblastic and osteoclastic activities: Analysis of bone metabolism using goldfish scale as a model for bone

    Science.gov (United States)

    Suzuki, N.; Kitamura, K.; Nemoto, T.; Shimizu, N.; Wada, S.; Kondo, T.; Tabata, M. J.; Sodeyama, F.; Ijiri, K.; Hattori, A.

    In osteoclastic activity during space flight as well as hind limb unloading by tail suspension, inconsistent results have been reported in an in vivo study. The bone matrix plays an important role in the response to physical stress. However, there is no suitable in vitro co-culture system of osteoblasts and osteoclasts including bone matrix. On the other hand, fish scale is a calcified tissue that contains osteoblasts, osteoclasts, and bone matrix, all of which are similar to those found in human bones. Recently, we developed a new in vitro model system using goldfish scale. This system can detect the activities of osteoclasts and osteoblasts with tartrate-resistant acid phosphatase and alkaline phosphatase as the respective markers and precisely analyze the co-relationship between osteoblasts and osteoclasts. Using this system, we analyzed the bone metabolism under various degrees of acceleration (0.5-, 1-, 2-, 4-, and 6-G) by vibration with a G-load apparatus. After loading for 5 and 10 min, the scales were incubated for 6 and 24 h. The osteoblastic and osteoclastic activities were then measured. The osteoblastic activities gradually increased corresponding to 1-G to 6-G acceleration. In addition, ER mRNA expression was the highest under 6-G acceleration. On the other hand, the osteoclastic activity decreased at 24 h of incubation under low acceleration (0.5- and 1-G). This change coincided with TRAP mRNA expression. Under 2-G acceleration, the strength of suppression in osteoclastic activity was the highest. The strength of the inhibitory action under 4- and 6-G acceleration was lower than that under 2-G acceleration. In our co-culture system, osteoblasts and osteoclasts in the scale sensitively responded to several degrees of acceleration. Therefore, we strongly believe that our in vitro co-culture system is useful for the analysis of bone metabolism under loading or unloading.

  2. Soy protein diet and exercise training increase relative bone volume and enhance bone microarchitecture in a mouse model of uremia.

    Science.gov (United States)

    Tomayko, Emily J; Chung, Hae R; Wilund, Kenneth R

    2011-11-01

    Soy protein consumption and exercise training have been widely studied for their effects on the vasculature and bone in healthy populations, but little is known about the effectiveness of these interventions in chronic kidney disease (CKD). Cardiovascular disease and bone fracture risk are significantly elevated in CKD, and current pharmacological interventions have been unsuccessful in treating these conditions simultaneously. The purpose of this study was to compare the effects of a soy protein diet and endurance exercise training, alone or in combination, on cardiovascular and bone health in a mouse model of renal insufficiency. At 8 weeks of age, 60 female apolipoprotein E(-/-) mice underwent a two-step surgical procedure to induce uremia. These mice were then randomized at 12 weeks of age to one of four treatment groups for the 16-week intervention period: sedentary, control diet (n = 16); sedentary, soy protein diet (n = 18); exercise, control diet (n = 14); and exercise, soy protein diet (n = 12). There were no significant treatment effects on atherosclerotic lesion areas or aortic calcium deposits. We demonstrated a significant main effect of both diet and exercise on relative bone volume, trabecular number, trabecular separation, and trabecular connective density in the proximal femur as measured by microcomputed tomography. There were no treatment effects on trabecular thickness. We also showed a main effect of diet on plasma urea levels. These data suggest that soy protein intake and exercise training exert beneficial effects on properties of bone and plasma urea levels in mice with surgically induced renal impairment. © The Japanese Society for Bone and Mineral Research and Springer 2011

  3. Handbook of structural equation modeling

    CERN Document Server

    Hoyle, Rick H

    2012-01-01

    The first comprehensive structural equation modeling (SEM) handbook, this accessible volume presents both the mechanics of SEM and specific SEM strategies and applications. The editor, contributors, and editorial advisory board are leading methodologists who have organized the book to move from simpler material to more statistically complex modeling approaches. Sections cover the foundations of SEM; statistical underpinnings, from assumptions to model modifications; steps in implementation, from data preparation through writing the SEM report; and basic and advanced applications, inclu

  4. Polarization in Raman spectroscopy helps explain bone brittleness in genetic mouse models

    Science.gov (United States)

    Makowski, Alexander J.; Pence, Isaac J.; Uppuganti, Sasidhar; Zein-Sabatto, Ahbid; Huszagh, Meredith C.; Mahadevan-Jansen, Anita; Nyman, Jeffry S.

    2014-11-01

    Raman spectroscopy (RS) has been extensively used to characterize bone composition. However, the link between bone biomechanics and RS measures is not well established. Here, we leveraged the sensitivity of RS polarization to organization, thereby assessing whether RS can explain differences in bone toughness in genetic mouse models for which traditional RS peak ratios are not informative. In the selected mutant mice-activating transcription factor 4 (ATF4) or matrix metalloproteinase 9 (MMP9) knock-outs-toughness is reduced but differences in bone strength do not exist between knock-out and corresponding wild-type controls. To incorporate differences in the RS of bone occurring at peak shoulders, a multivariate approach was used. Full spectrum principal components analysis of two paired, orthogonal bone orientations (relative to laser polarization) improved genotype classification and correlation to bone toughness when compared to traditional peak ratios. When applied to femurs from wild-type mice at 8 and 20 weeks of age, the principal components of orthogonal bone orientations improved age classification but not the explanation of the maturation-related increase in strength. Overall, increasing polarization information by collecting spectra from two bone orientations improves the ability of multivariate RS to explain variance in bone toughness, likely due to polarization sensitivity to organizational changes in both mineral and collagen.

  5. A mathematical multiscale model of bone remodeling, accounting for pore space-specific mechanosensation.

    Science.gov (United States)

    Pastrama, Maria-Ioana; Scheiner, Stefan; Pivonka, Peter; Hellmich, Christian

    2018-02-01

    While bone tissue is a hierarchically organized material, mathematical formulations of bone remodeling are often defined on the level of a millimeter-sized representative volume element (RVE), "smeared" over all types of bone microstructures seen at lower observation scales. Thus, there is no explicit consideration of the fact that the biological cells and biochemical factors driving bone remodeling are actually located in differently sized pore spaces: active osteoblasts and osteoclasts can be found in the vascular pores, whereas the lacunar pores host osteocytes - bone cells originating from former osteoblasts which were then "buried" in newly deposited extracellular bone matrix. We here propose a mathematical description which considers size and shape of the pore spaces where the biological and biochemical events take place. In particular, a previously published systems biology formulation, accounting for biochemical regulatory mechanisms such as the rank-rankl-opg pathway, is cast into a multiscale framework coupled to a poromicromechanical model. The latter gives access to the vascular and lacunar pore pressures arising from macroscopic loading. Extensive experimental data on the biological consequences of this loading strongly suggest that the aforementioned pore pressures, together with the loading frequency, are essential drivers of bone remodeling. The novel approach presented here allows for satisfactory simulation of the evolution of bone tissue under various loading conditions, and for different species; including scenarios such as mechanical dis- and overuse of murine and human bone, or in osteocyte-free bone. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. Effects of Nrf2 Deficiency on Bone Microarchitecture in an Experimental Model of Osteoporosis

    Directory of Open Access Journals (Sweden)

    Lidia Ibáñez

    2014-01-01

    Full Text Available Objective. Redox imbalance contributes to bone fragility. We have evaluated the in vivo role of nuclear factor erythroid derived 2-related factor-2 (Nrf2, an important regulator of cellular responses to oxidative stress, in bone metabolism using a model of postmenopausal osteoporosis. Methods. Ovariectomy was performed in both wild-type and mice deficient in Nrf2 (Nrf2−/−. Bone microarchitecture was analyzed by μCT. Serum markers of bone metabolism were also measured. Reactive oxygen species production was determined using dihydrorhodamine 123. Results. Sham-operated or ovariectomized Nrf2−/− mice exhibit a loss in trabecular bone mineral density in femur, accompanied by a reduction in cortical area in vertebrae. Nrf2 deficiency tended to increase osteoblastic markers and significantly enhanced osteoclastic markers in sham-operated animals indicating an increased bone turnover with a main effect on bone resorption. We have also shown an increased production of oxidative stress in bone marrow-derived cells from sham-operated or ovariectomized Nrf2−/− mice and a higher responsiveness of bone marrow-derived cells to osteoclastogenic stimuli in vitro. Conclusion. We have demonstrated in vivo a key role of Nrf2 in the maintenance of bone microarchitecture.

  7. Probiotic L. reuteri treatment prevents bone loss in a menopausal ovariectomized mouse model.

    Science.gov (United States)

    Britton, Robert A; Irwin, Regina; Quach, Darin; Schaefer, Laura; Zhang, Jing; Lee, Taehyung; Parameswaran, Narayanan; McCabe, Laura R

    2014-11-01

    Estrogen deficiency is a major risk factor for osteoporosis that is associated with bone inflammation and resorption. Half of women over the age of 50 will experience an osteoporosis related fracture in their lifetime, thus novel therapies are needed to combat post-menopausal bone loss. Recent studies suggest an important role for gut-bone signaling pathways and the microbiota in regulating bone health. Given that the bacterium Lactobacillus reuteri ATCC PTA 6475 (L. reuteri) secretes beneficial immunomodulatory factors, we examined if this candidate probiotic could reduce bone loss associated with estrogen deficiency in an ovariectomized (Ovx) mouse menopausal model. Strikingly, L. reuteri treatment significantly protected Ovx mice from bone loss. Osteoclast bone resorption markers and activators (Trap5 and RANKL) as well as osteoclastogenesis are significantly decreased in L. reuteri-treated mice. Consistent with this, L. reuteri suppressed Ovx-induced increases in bone marrow CD4+ T-lymphocytes (which promote osteoclastogenesis) and directly suppressed osteoclastogenesis in vitro. We also identified that L. reuteri treatment modifies microbial communities in the Ovx mouse gut. Together, our studies demonstrate that L. reuteri treatment suppresses bone resorption and loss associated with estrogen deficiency. Thus, L. reuteri treatment may be a straightforward and cost-effective approach to reduce post-menopausal bone loss. © 2014 Wiley Periodicals, Inc.

  8. Medium-Term Function of a 3D Printed TCP/HA Structure as a New Osteoconductive Scaffold for Vertical Bone Augmentation: A Simulation by BMP-2 Activation

    Directory of Open Access Journals (Sweden)

    Mira Moussa

    2015-04-01

    Full Text Available Introduction: A 3D-printed construct made of orthogonally layered strands of tricalcium phosphate (TCP and hydroxyapatite has recently become available. The material provides excellent osteoconductivity. We simulated a medium-term experiment in a sheep calvarial model by priming the blocks with BMP-2. Vertical bone growth/maturation and material resorption were evaluated. Materials and methods: Titanium hemispherical caps were filled with either bare- or BMP-2 primed constructs and placed onto the calvaria of adult sheep (n = 8. Histomorphometry was performed after 8 and 16 weeks. Results: After 8 weeks, relative to bare constructs, BMP-2 stimulation led to a two-fold increase in bone volume (Bare: 22% ± 2.1%; BMP-2 primed: 50% ± 3% and a 3-fold decrease in substitute volume (Bare: 47% ± 5%; BMP-2 primed: 18% ± 2%. These rates were still observed at 16 weeks. The new bone grew and matured to a haversian-like structure while the substitute material resorbed via cell- and chemical-mediation. Conclusion: By priming the 3D construct with BMP-2, bone metabolism was physiologically accelerated, that is, enhancing vertical bone growth and maturation as well as material bioresorption. The scaffolding function of the block was maintained, leaving time for the bone to grow and mature to a haversian-like structure. In parallel, the material resorbed via cell-mediated and chemical processes. These promising results must be confirmed in clinical tests.

  9. Muscle size, strength, and physical performance and their associations with bone structure in the Hertfordshire Cohort Study.

    Science.gov (United States)

    Edwards, Mark H; Gregson, Celia L; Patel, Harnish P; Jameson, Karen A; Harvey, Nicholas C; Sayer, Avan Aihie; Dennison, Elaine M; Cooper, Cyrus

    2013-11-01

    Sarcopenia is associated with a greater fracture risk. This relationship was originally thought to be explained by an increased risk of falls in sarcopenic individuals. However, in addition, there is growing evidence of a functional muscle-bone unit in which bone health may be directly influenced by muscle function. Because a definition of sarcopenia encompasses muscle size, strength, and physical performance, we investigated relationships for each of these with bone size, bone density, and bone strength to interrogate these hypotheses further in participants from the Hertfordshire Cohort Study. A total of 313 men and 318 women underwent baseline assessment of health and detailed anthropometric measurements. Muscle strength was measured by grip strength, and physical performance was determined by gait speed. Peripheral quantitative computed tomography (pQCT) examination of the calf and forearm was performed to assess muscle cross-sectional area (mCSA) at the 66% level and bone structure (radius 4% and 66% levels; tibia 4% and 38% levels). Muscle size was positively associated with bone size (distal radius total bone area β = 17.5 mm2 /SD [12.0, 22.9]) and strength (strength strain index (β = 23.3 mm3 /SD [18.2, 28.4]) amongst women (p gait speed and bone structure were not seen. We conclude that although muscle size and grip strength are associated with bone size and strength, relationships between gait speed and bone structure and strength were not apparent in this cohort, supporting a role for the muscle-bone unit. © 2013 American Society for Bone and Mineral Research.

  10. Differences in tibial subchondral bone structure evaluated using plain radiographs between knees with and without cartilage damage or bone marrow lesions. The Oulu knee osteoarthritis study

    Energy Technology Data Exchange (ETDEWEB)

    Hirvasniemi, Jukka [University of Oulu, Research Unit of Medical Imaging, Physics and Technology, Faculty of Medicine, Oulu (Finland); Oulu University Hospital and University of Oulu, Medical Research Center Oulu, Oulu (Finland); Thevenot, Jerome; Podlipska, Jana [University of Oulu, Research Unit of Medical Imaging, Physics and Technology, Faculty of Medicine, Oulu (Finland); University of Oulu, Infotech Oulu, Oulu (Finland); Guermazi, Ali [Boston University School of Medicine, Quantitative Imaging Center, Department of Radiology, Boston, MA (United States); Roemer, Frank W. [Boston University School of Medicine, Quantitative Imaging Center, Department of Radiology, Boston, MA (United States); University of Erlangen-Nuremberg, Department of Radiology, Erlangen (Germany); Nieminen, Miika T.; Saarakkala, Simo [University of Oulu, Research Unit of Medical Imaging, Physics and Technology, Faculty of Medicine, Oulu (Finland); Oulu University Hospital and University of Oulu, Medical Research Center Oulu, Oulu (Finland); University of Oulu, Infotech Oulu, Oulu (Finland); Oulu University Hospital, Department of Diagnostic Radiology, Oulu (Finland)

    2017-11-15

    To investigate whether subchondral bone structure from plain radiographs is different between subjects with and without articular cartilage damage or bone marrow lesions (BMLs). Radiography-based bone structure was assessed from 80 subjects with different stages of knee osteoarthritis using entropy of Laplacian-based image (E{sub Lap}) and local binary patterns (E{sub LBP}), homogeneity index of local angles (HI{sub Angles,mean}), and horizontal (FD{sub Hor}) and vertical fractal dimensions (FD{sub Ver}). Medial tibial articular cartilage damage and BMLs were scored using the magnetic resonance imaging osteoarthritis knee score. Level of statistical significance was set to p < 0.05. Subjects with medial tibial cartilage damage had significantly higher FD{sub Ver} and E{sub LBP} as well as lower E{sub Lap} and HI{sub Angles,mean} in the medial tibial subchondral bone region than subjects without damage. FD{sub Hor}, FD{sub Ver}, and E{sub LBP} were significantly higher, whereas E{sub Lap} and HI{sub Angles,mean} were lower in the medial trabecular bone region. Subjects with medial tibial BMLs had significantly higher FD{sub Ver} and E{sub LBP} as well as lower E{sub Lap} and HI{sub Angles,mean} in medial tibial subchondral bone. FD{sub Hor}, FD{sub Ver}, and E{sub LBP} were higher, whereas E{sub Lap} and HI{sub Angles,mean} were lower in medial trabecular bone. Our results support the use of bone structural analysis from radiographs when examining subjects with osteoarthritis or at risk of having it. (orig.)

  11. Myostatin deficiency partially rescues the bone phenotype of osteogenesis imperfecta model mice.

    Science.gov (United States)

    Oestreich, A K; Carleton, S M; Yao, X; Gentry, B A; Raw, C E; Brown, M; Pfeiffer, F M; Wang, Y; Phillips, C L

    2016-01-01

    Mice with osteogenesis imperfecta (+/oim), a disorder of bone fragility, were bred to mice with muscle over growth to test whether increasing muscle mass genetically would improve bone quality and strength. The results demonstrate that femora from mice carrying both mutations have greater mechanical integrity than their +/oim littermates. Osteogenesis imperfecta is a heritable connective tissue disorder due primarily to mutations in the type I collagen genes resulting in skeletal deformity and fragility. Currently, there is no cure, and therapeutic strategies encompass the use of antiresorptive pharmaceuticals and surgical bracing, with limited success and significant potential for adverse effects. Bone, a mechanosensing organ, can respond to high mechanical loads by increasing new bone formation and altering bone geometry to withstand increased forces. Skeletal muscle is a major source of physiological loading on bone, and bone strength is proportional to muscle mass. To test the hypothesis that congenic increases in muscle mass in the osteogenesis imperfecta murine model mouse (oim) will improve their compromised bone quality and strength, heterozygous (+/oim) mice were bred to mice deficient in myostatin (+/mstn), a negative regulator of muscle growth. The resulting adult offspring were evaluated for hindlimb muscle mass, and bone microarchitecture, physiochemistry, and biomechanical integrity. +/oim mice deficient in myostatin (+/mstn +/oim) were generated and demonstrated that myostatin deficiency increased body weight, muscle mass, and biomechanical strength in +/mstn +/oim mice as compared to +/oim mice. Additionally, myostatin deficiency altered the physiochemical properties of the +/oim bone but did not alter bone remodeling. Myostatin deficiency partially improved the reduced femoral bone biomechanical strength of adult +/oim mice by increasing muscle mass with concomitant improvements in bone microarchitecture and physiochemical properties.

  12. Investigation of composition and structure of spongy and hard bone tissue using FTIR spectroscopy, XRD and SEM

    Science.gov (United States)

    Al-Akhras, M.-Ali H.; Hasan Qaseer, M. K.; Albiss, B. A.; Alebrhim, M. Anwar; Gezawa, Umar S.

    2018-02-01

    Valuable structural and chemical features can be obtained for spongy and hard bone by infrared spectroscopy and X-ray diffraction. A better understanding of chemical and structural differences between spongy and hard bone is a very important contributor to bone quality. Our data according to IR data showed that the collagen cross-links occurred to be higher in spongy bone, and crystallinity was lower in spongy bone. Deconvolution of the infrared band near 870 cm-1 reveals evidence for A2-type carbonate substitution on hydroxyapatite of spongy bone in addition to the A and B type carbonate substitution that are also found in hard bone. IR and XRD data confirmed the results of each other since full width at half maximum of 002-apatite pattern of XRD showed that the crystallinity was lower in spongy bone. The microstructure was examined by using scanning electron microscope and the result showed that the lattice of thin threads in spongy bone and is less dense than hard bone.

  13. Use of organometallic chelates in broiler diet: effect on the performance and bone structure. Preliminary results

    Directory of Open Access Journals (Sweden)

    Biagina Chiofalo

    2010-01-01

    Full Text Available On 26,000 Ross 508 broiler chickens (two groups of 13,000 per pen the effect of dietary substitution with in organic trace minerals or organometallic chelates on performances and bones tructure c trace minerals or organometallic chelates on performances and bone structure was studied. Treatments consisted of a commercial diet integrated with 0.5% of a vitamin-mineral premix containing inorganic trace minerals (CTR or organometallic chelates (MHA using Methionine Hydroxy Analog. Production performance was measured during the 52 d trial period and bone structure was evalu- ated at the slaughter (52 d. Significant (P=0.038 higher values were observed in the finishing period (41 to 52 d for the body weight of the treated group (3560 g vs. 3358 g. The same trend was observed for the ADG (MHA 87.6 g/d vs. CTR 71 g/d; P<0.05. Concerning ash percentage significant higher values were observed in the CTR group for femur (49.01% vs. 51.45%; P<0.01 and tibia (53.87% vs. 49.79%; P<0.001; femur showed also higher values for bone radiopacity (MHA 0.21 px vs. CTR 0.26 px; P=0.035. MHA group showed significant higher value for morphometric measures of the femur and tibia. Results suggest that organometallic chelates can be included in the diet without compromising broiler performance.

  14. Characterization of synthetic foam structures used to manufacture artificial vertebral trabecular bone.

    Science.gov (United States)

    Fürst, David; Senck, Sascha; Hollensteiner, Marianne; Esterer, Benjamin; Augat, Peter; Eckstein, Felix; Schrempf, Andreas

    2017-07-01

    Artificial materials reflecting the mechanical properties of human bone are essential for valid and reliable implant testing and design. They also are of great benefit for realistic simulation of surgical procedures. The objective of this study was therefore to characterize two groups of self-developed synthetic foam structures by static compressive testing and by microcomputed tomography. Two mineral fillers and varying amounts of a blowing agent were used to create different expansion behavior of the synthetic open-cell foams. The resulting compressive and morphometric properties thus differed within and also slightly between both groups. Apart from the structural anisotropy, the compressive and morphometric properties of the synthetic foam materials were shown to mirror the respective characteristics of human vertebral trabecular bone in good approximation. In conclusion, the artificial materials created can be used to manufacture valid synthetic bones for surgical training. Further, they provide novel possibilities for studying the relationship between trabecular bone microstructure and biomechanical properties. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Probabilistic models for structured sparsity

    DEFF Research Database (Denmark)

    Andersen, Michael Riis

    of each time series is decomposed into a non-negative linear combination of elements from a dictionary of shared covariance matrix components. A variational Bayes algorithm is derived for approximate posterior inference. The proposed model is validated using a functional magnetic resonance imaging (f......Sparsity has become an increasingly popular choice of regularization in machine learning and statistics. The sparsity assumption for a matrixX means that most of the entries in X are equal to exactly zero. Structured sparsity is generalization of sparsity and assumes that the set of locations...... of the non-zero coefficients in X contains structure that can be exploited. This thesis deals with probabilistic models for structured sparsity for regularization of ill-posed problems. The aim of the thesis is two-fold; to construct sparsity promoting prior distributions for structured sparsity...

  16. Zoledronic acid improves bone histomorphometry in a murine model of Rett syndrome.

    Science.gov (United States)

    Shapiro, Jay R; Boskey, Adele L; Doty, Stephen B; Lukashova, Lyudmila; Blue, Mary E

    2017-06-01

    Rett syndrome (RTT) is a neurodevelopmental disorder predominately affecting young females, caused by deficiency of the global transcriptional protein methyl CpG binding protein 2 (MeCP2). Osteoblasts express MeCP2 and girls with RTT experience early onset osteoporosis, decreased bone mass and an increased fracture risk. There is no defined treatment for osteoporosis associated with RTT. The present study evaluated the effects of zoledronic acid (ZA), a third generation nitrogen-containing bisphosphonate with primarily anti-osteoclastic activity, in a mouse model of MeCP2 deficiency. Mice received weekly injections of 20μg/kg ZA for six weeks. Due to the shortened lifespan of hemizygous male (Mecp2-null) mice, treatment began at 3weeks of age for this group and corresponding wildtype (WT) male mice. Treatment for heterozygous (HET) and WT female mice began at 8weeks of age. Micro-computed tomography (micro-CT) and dynamic analyses of bone turnover were performed. ZA treatment led to significant increases in bone volume fraction, number, connectivity density and apparent density of trabecular bone in all genotypes of mice. In contrast, cortical bone generally was unaffected by ZA injections. Parameters of bone turnover, including mineral apposition rate, labeled bone surface and bone formation rate decreased after treatment with ZA. Mecp2-null mice had reduced labeled bone surface and bone formation rate compared to WT male mice. The results indicate that ZA treatment significantly improved trabecular bone mass in a murine model of RTT with little effect on cortical bone. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. Evaluation of injectable silica-embedded nanohydroxyapatite bone substitute in a rat tibia defect model.

    Science.gov (United States)

    Xu, Weiguo; Ganz, Cornelia; Weber, Ulf; Adam, Martin; Holzhüter, Gerd; Wolter, Daniel; Frerich, Bernhard; Vollmar, Brigitte; Gerber, Thomas

    2011-01-01

    In clinical practice, vertebral compression fractures occur after trauma and osteoporosis. Kyphoplasty is a minimally invasive procedure using bone filler material for the treatment of such fractures. A full synthetic injectable bone substitute (SIBS) was manufactured by means of spray drying. The aim of this study was to characterize the SIBS and to analyze the remodelling process during degradation of the biomaterial and new bone formation after implantation. SIBS is an aqueous suspension of donut-like microparticles. These microparticles consist of nanocrystallites of synthetic hydroxyapatite embedded in amorphous silica gel. After implantation of SIBS in a proximal tibial diaphyseal defect in 52 rats, grafts were harvested for subsequent analysis on different days. Newly formed bone originating from endosteum was observed on day 6. Hematomas in the medullary space and cortical wounds disappeared on day 12. The wound region was completely replaced by a composite of newly formed cancellous bone, extracellular matrix, and SIBS. At day 63 the cortical defect was fully healed by bone, while newly formed bone in the medullary space almost disappeared and was replaced with bone marrow. In conclusion, SIBS demonstrated a unique structure with osteoinductive and bioresorbable properties, which induced fast bone regeneration. Therefore, a clinical application of SIBS for kyphoplasty is promising.

  18. TEMPORAL MODELING OF DNA DEGRADATION IN BONE REMAINS

    Directory of Open Access Journals (Sweden)

    Andrei Stefan

    2012-06-01

    Full Text Available The aim of this study is to follow the changes that occur, in time, at DNA level and to establish an efficient and reliable protocol for ancestral DNA extraction from bones found in archaeological sites. To test whether the protocol is efficient and capable of yielding good quality DNA, extraction was first performed on fresh bones. The material consists of fresh pig (Sus scrofa and cow (Bos taurus bones that were grounded by using a drill operating at low speed. The bone powder was then incubated in lysis buffer in the presence of proteinase K. DNA isolation and purification were done by using the phenol:chloroform protocol and DNA was precipitated with absolute ethanol stored at -20oC. The extractions were carried out once every month for a total of four extractions

  19. Mechanical Properties of Optimized Diamond Lattice Structure for Bone Scaffolds Fabricated via Selective Laser Melting

    Science.gov (United States)

    Zhang, David Z.; Zhang, Peng; Zhao, Miao; Jafar, Salman

    2018-01-01

    Developments in selective laser melting (SLM) have enabled the fabrication of periodic cellular lattice structures characterized by suitable properties matching the bone tissue well and by fluid permeability from interconnected structures. These multifunctional performances are significantly affected by cell topology and constitutive properties of applied materials. In this respect, a diamond unit cell was designed in particular volume fractions corresponding to the host bone tissue and optimized with a smooth surface at nodes leading to fewer stress concentrations. There were 33 porous titanium samples with different volume fractions, from 1.28 to 18.6%, manufactured using SLM. All of them were performed under compressive load to determine the deformation and failure mechanisms, accompanied by an in-situ approach using digital image correlation (DIC) to reveal stress–strain evolution. The results showed that lattice structures manufactured by SLM exhibited comparable properties to those of trabecular bone, avoiding the effects of stress-shielding and increasing longevity of implants. The curvature of optimized surface can play a role in regulating the relationship between density and mechanical properties. Owing to the release of stress concentration from optimized surface, the failure mechanism of porous titanium has been changed from the pattern of bottom-up collapse by layer (or cell row) to that of the diagonal (45°) shear band, resulting in the significant enhancement of the structural strength. PMID:29510492

  20. Mechanical Properties of Optimized Diamond Lattice Structure for Bone Scaffolds Fabricated via Selective Laser Melting.

    Science.gov (United States)

    Liu, Fei; Zhang, David Z; Zhang, Peng; Zhao, Miao; Jafar, Salman

    2018-03-03

    Developments in selective laser melting (SLM) have enabled the fabrication of periodic cellular lattice structures characterized by suitable properties matching the bone tissue well and by fluid permeability from interconnected structures. These multifunctional performances are significantly affected by cell topology and constitutive properties of applied materials. In this respect, a diamond unit cell was designed in particular volume fractions corresponding to the host bone tissue and optimized with a smooth surface at nodes leading to fewer stress concentrations. There were 33 porous titanium samples with different volume fractions, from 1.28 to 18.6%, manufactured using SLM. All of them were performed under compressive load to determine the deformation and failure mechanisms, accompanied by an in-situ approach using digital image correlation (DIC) to reveal stress-strain evolution. The results showed that lattice structures manufactured by SLM exhibited comparable properties to those of trabecular bone, avoiding the effects of stress-shielding and increasing longevity of implants. The curvature of optimized surface can play a role in regulating the relationship between density and mechanical properties. Owing to the release of stress concentration from optimized surface, the failure mechanism of porous titanium has been changed from the pattern of bottom-up collapse by layer (or cell row) to that of the diagonal (45°) shear band, resulting in the significant enhancement of the structural strength.

  1. Tissue-engineered 3D cancer-in-bone modeling: silk and PUR protocols.

    Science.gov (United States)

    Dadwal, Ushashi; Falank, Carolyne; Fairfield, Heather; Linehan, Sarah; Rosen, Clifford J; Kaplan, David L; Sterling, Julie; Reagan, Michaela R

    2016-01-01

    Cancers that metastasize or grow in the bone marrow are typically considered incurable and cause extensive damage to the bone and bone marrow. The bone is a complex, dynamic, three-dimensional (3D) environment composed of a plethora of cells that may contribute to, or constrain, the growth of tumor cells and development of bone disease. The development of safe and effective drugs is currently hampered by pre-clinical two-dimensional (2D) models whose poor predictive power does not accurately predict the success or failure of therapeutics. These inadequate models often result in drugs proceeding through extensive pre-clinical studies only to fail clinically. Consistently, 3D co-culture systems prove superior to 2D mono-cultures in modeling in vivo cell phenotypes, disease progression and response to therapeutics. As a complex, multicellular, multidimensional bone microenvironment, 3D models allow for more accurate predictions of tumor growth, cell-cell and cell-matrix interactions, and resulting therapeutic responses. In this review we will discuss various 3D models available and describe step-by-step protocols for two of the most well-established 3D culture models for studying tumor-induced bone disease.

  2. Effect of Hydroxyapatite on Bone Integration in a Rabbit Tibial Defect Model

    Science.gov (United States)

    Sohn, Sung-Keun; Kim, Kyung-Taek; Kim, Chul-Hong; Ahn, Hee-Bae; Rho, Mee-Sook; Jeong, Min-Ho; Sun, Sang-Kyu

    2010-01-01

    Background The aim of the present study was to prepare hydroxyapatite (HA) and then characterize its effect on bone integration in a rabbit tibial defect model. The bone formation with different designs of HA was compared and the bony integration of several graft materials was investigated qualitatively by radiologic and histologic study. Methods Ten rabbits were included in this study; two holes were drilled bilaterally across the near cortex and the four holes in each rabbit were divided into four treatment groups (HAP, hydroxyapatite powder; HAC, hydroxyapatite cylinder; HA/TCP, hydroxyapatite/tri-calcium phosphate cylinder, and titanium cylinder). The volume of bone ingrowth and the change of bone mineral density were statistically calculated by computed tomography five times for each treatment group at 0, 2, 4, 6, and 8 weeks after grafting. Histologic analysis was performed at 8 weeks after grafting. Results The HAP group showed the most pronounced effect on the bone ingrowth surface area, which seen at 4, 6, and 8 weeks after graft (p 0.05). On histological examination, the HAP group revealed well-recovered cortical bone, but the bone was irregularly thickened and haphazardly admixed with powder. The HAC group showed similar histological features to those of the HA/TCP group; the cortical surface of the newly developed bone was smooth and the bone matrix on the surface of the cylinder was regularly arranged. Conclusions We concluded that both the hydroxyapatite powder and cylinder models investigated in our study may be suitable as a bone substitute in the rabbit tibial defect model, but their characteristic properties are quite different. In contrast to hydroxyapatite powder, which showed better results for the bone ingrowth surface, the hydroxyapatite cylinder showed better results for the sustained morphology. PMID:20514266

  3. Testing the Hypothesis of Biofilm as a Source for Soft Tissue and Cell-Like Structures Preserved in Dinosaur Bone

    OpenAIRE

    Schweitzer, Mary Higby; Moyer, Alison E.; Zheng, Wenxia

    2016-01-01

    Recovery of still-soft tissue structures, including blood vessels and osteocytes, from dinosaur bone after demineralization was reported in 2005 and in subsequent publications. Despite multiple lines of evidence supporting an endogenous source, it was proposed that these structures arose from contamination from biofilm-forming organisms. To test the hypothesis that soft tissue structures result from microbial invasion of the fossil bone, we used two different biofilm-forming microorganisms to...

  4. Engraftment of Prevascularized, Tissue Engineered Constructs in a Novel Rabbit Segmental Bone Defect Model

    Directory of Open Access Journals (Sweden)

    Alexandre Kaempfen

    2015-06-01

    Full Text Available The gold standard treatment of large segmental bone defects is autologous bone transfer, which suffers from low availability and additional morbidity. Tissue engineered bone able to engraft orthotopically and a suitable animal model for pre-clinical testing are direly needed. This study aimed to evaluate engraftment of tissue-engineered bone with different prevascularization strategies in a novel segmental defect model in the rabbit humerus. Decellularized bone matrix (Tutobone seeded with bone marrow mesenchymal stromal cells was used directly orthotopically or combined with a vessel and inserted immediately (1-step or only after six weeks of subcutaneous “incubation” (2-step. After 12 weeks, histological and radiological assessment was performed. Variable callus formation was observed. No bone formation or remodeling of the graft through TRAP positive osteoclasts could be detected. Instead, a variable amount of necrotic tissue formed. Although necrotic area correlated significantly with amount of vessels and the 2-step strategy had significantly more vessels than the 1-step strategy, no significant reduction of necrotic area was found. In conclusion, the animal model developed here represents a highly challenging situation, for which a suitable engineered bone graft with better prevascularization, better resorbability and higher osteogenicity has yet to be developed.

  5. Single dose of bisphosphonate preserves gains in bone mass following cessation of sclerostin antibody in Brtl/+ osteogenesis imperfecta model.

    Science.gov (United States)

    Perosky, Joseph E; Khoury, Basma M; Jenks, Terese N; Ward, Ferrous S; Cortright, Kai; Meyer, Bethany; Barton, David K; Sinder, Benjamin P; Marini, Joan C; Caird, Michelle S; Kozloff, Kenneth M

    2016-12-01

    Sclerostin antibody has demonstrated a bone-forming effect in pre-clinical models of osteogenesis imperfecta, where mutations in collagen or collagen-associated proteins often result in high bone fragility in pediatric patients. Cessation studies in osteoporotic patients have demonstrated that sclerostin antibody, like intermittent PTH treatment, requires sequential anti-resorptive therapy to preserve the anabolic effects in adult populations. However, the persistence of anabolic gains from either drug has not been explored clinically in OI, or in any animal model. To determine whether cessation of sclerostin antibody therapy in a growing OI skeleton requires sequential anti-resorptive treatment to preserve anabolic gains in bone mass, we treated 3week old Brtl/+ and wild type mice for 5weeks with SclAb, and then withdrew treatment for an additional 6weeks. Trabecular bone loss was evident following cessation, but was preserved in a dose-dependent manner with single administration of pamidronate at the time of cessation. In vivo longitudinal near-infrared optical imaging of cathepsin K activation in the proximal tibia suggests an anti-resorptive effect of both SclAb and pamidronate which is reversed after three weeks of cessation. Cortical bone was considerably less susceptible to cessation effects, and showed no structural or functional deficits in the absence of pamidronate during this cessation period. In conclusion, while SclAb induces a considerable anabolic gain in the rapidly growing Brtl/+ murine model of OI, a single sequential dose of antiresorptive drug is required to maintain bone mass at trabecular sites for 6weeks following cessation. Copyright © 2016 Elsevier Inc. All rights reserved.

  6. Effect of porous orthopaedic implant material and structure on load sharing with simulated bone ingrowth: A finite element analysis comparing titanium and PEEK.

    Science.gov (United States)

    Carpenter, R Dana; Klosterhoff, Brett S; Torstrick, F Brennan; Foley, Kevin T; Burkus, J Kenneth; Lee, Christopher S D; Gall, Ken; Guldberg, Robert E; Safranski, David L

    2018-04-01

    Osseointegration of load-bearing orthopaedic implants, including interbody fusion devices, is critical to long-term biomechanical functionality. Mechanical loads are a key regulator of bone tissue remodeling and maintenance, and stress-shielding due to metal orthopaedic implants being much stiffer than bone has been implicated in clinical observations of long-term bone loss in tissue adjacent to implants. Porous features that accommodate bone ingrowth have improved implant fixation in the short term, but long-term retrieval studies have sometimes demonstrated limited, superficial ingrowth into the pore layer of metal implants and aseptic loosening remains a problem for a subset of patients. Polyether-ether-ketone (PEEK) is a widely used orthopaedic material with an elastic modulus more similar to bone than metals, and a manufacturing process to form porous PEEK was recently developed to allow bone ingrowth while preserving strength for load-bearing applications. To investigate the biomechanical implications of porous PEEK compared to porous metals, we analyzed finite element (FE) models of the pore structure-bone interface using two clinically available implants with high (> 60%) porosity, one being constructed from PEEK and the other from electron beam 3D-printed titanium (Ti). The objective of this study was to investigate how porous PEEK and porous Ti mechanical properties affect load sharing with bone within the porous architectures over time. Porous PEEK substantially increased the load share transferred to ingrown bone compared to porous Ti under compression (i.e. at 4 weeks: PEEK = 66%; Ti = 13%), tension (PEEK = 71%; Ti = 12%), and shear (PEEK = 68%; Ti = 9%) at all time points of simulated bone ingrowth. Applying PEEK mechanical properties to the Ti implant geometry and vice versa demonstrated that the observed increases in load sharing with PEEK were primarily due to differences in intrinsic elastic modulus and not pore architecture (i.e. 4 weeks

  7. Structural and Mechanical Improvements to Bone Are Strain Dependent with Axial Compression of the Tibia in Female C57BL/6 Mice.

    Directory of Open Access Journals (Sweden)

    Alycia G Berman

    Full Text Available Strain-induced adaption of bone has been well-studied in an axial loading model of the mouse tibia. However, most outcomes of these studies are restricted to changes in bone architecture and do not explore the mechanical implications of those changes. Herein, we studied both the mechanical and morphological adaptions of bone to three strain levels using a targeted tibial loading mouse model. We hypothesized that loading would increase bone architecture and improve cortical mechanical properties in a dose-dependent fashion. The right tibiae of female C57BL/6 mice (8 week old were compressively loaded for 2 weeks to a maximum compressive force of 8.8N, 10.6N, or 12.4N (generating periosteal strains on the anteromedial region of the mid-diaphysis of 1700 με, 2050 με, or 2400 με as determined by a strain calibration, while the left limb served as an non-loaded control. Following loading, ex vivo analyses of bone architecture and cortical mechanical integrity were assessed by micro-computed tomography and 4-point bending. Results indicated that loading improved bone architecture in a dose-dependent manner and improved mechanical outcomes at 2050 με. Loading to 2050 με resulted in a strong and compelling formation response in both cortical and cancellous regions. In addition, both structural and tissue level strength and energy dissipation were positively impacted in the diaphysis. Loading to the highest strain level also resulted in rapid and robust formation of bone in both cortical and cancellous regions. However, these improvements came at the cost of a woven bone response in half of the animals. Loading to the lowest strain level had little effect on bone architecture and failed to impact structural- or tissue-level mechanical properties. Potential systemic effects were identified for trabecular bone volume fraction, and in the pre-yield region of the force-displacement and stress-strain curves. Future studies will focus on a moderate

  8. Deregulation of arginase induces bone complications in high-fat/high-sucrose diet diabetic mouse model.

    Science.gov (United States)

    Bhatta, Anil; Sangani, Rajnikumar; Kolhe, Ravindra; Toque, Haroldo A; Cain, Michael; Wong, Abby; Howie, Nicole; Shinde, Rahul; Elsalanty, Mohammed; Yao, Lin; Chutkan, Norman; Hunter, Monty; Caldwell, Ruth B; Isales, Carlos; Caldwell, R William; Fulzele, Sadanand

    2016-02-15

    A balanced diet is crucial for healthy development and prevention of musculoskeletal related diseases. Diets high in fat content are known to cause obesity, diabetes and a number of other disease states. Our group and others have previously reported that activity of the urea cycle enzyme arginase is involved in diabetes-induced dysregulation of vascular function due to decreases in nitric oxide formation. We hypothesized that diabetes may also elevate arginase activity in bone and bone marrow, which could lead to bone-related complications. To test this we determined the effects of diabetes on expression and activity of arginase, in bone and bone marrow stromal cells (BMSCs). We demonstrated that arginase 1 is abundantly present in the bone and BMSCs. We also demonstrated that arginase activity and expression in bone and bone marrow is up-regulated in models of diabetes induced by HFHS diet and streptozotocin (STZ). HFHS diet down-regulated expression of healthy bone metabolism markers (BMP2, COL-1, ALP, and RUNX2) and reduced bone mineral density, bone volume and trabecular thickness. However, treatment with an arginase inhibitor (ABH) prevented these bone-related complications of diabetes. In-vitro study of BMSCs showed that high glucose treatment increased arginase activity and decreased nitric oxide production. These effects were reversed by treatment with an arginase inhibitor (ABH). Our study provides evidence that deregulation of l-arginine metabolism plays a vital role in HFHS diet-induced diabetic complications and that these complications can be prevented by treatment with arginase inhibitors. The modulation of l-arginine metabolism in disease could offer a novel therapeutic approach for osteoporosis and other musculoskeletal related diseases. Published by Elsevier Ireland Ltd.

  9. An interface finite element model can be used to predict healing outcome of bone fractures.

    Science.gov (United States)

    Alierta, J A; Pérez, M A; García-Aznar, J M

    2014-01-01

    After fractures, bone can experience different potential outcomes: successful bone consolidation, non-union and bone failure. Although, there are a lot of factors that influence fracture healing, experimental studies have shown that the interfragmentary movement (IFM) is one of the main regulators for the course of bone healing. In this sense, computational models may help to improve the development of mechanical-based treatments for bone fracture healing. Hence, based on this fact, we propose a combined repair-failure mechanistic computational model to describe bone fracture healing. Despite being a simple model, it is able to correctly estimate the time course evolution of the IFM compared to in vivo measurements under different mechanical conditions. Therefore, this mathematical approach is especially suitable for modeling the healing response of bone to fractures treated with different mechanical fixators, simulating realistic clinical conditions. This model will be a useful tool to identify factors and define targets for patient specific therapeutics interventions. © 2013 Published by Elsevier Ltd.

  10. Experimental model for bone regeneration in oral and cranio-maxillo-facial surgery.

    Science.gov (United States)

    Mardas, Nikos; Dereka, Xanthippi; Donos, Nikolaos; Dard, Michel

    2014-02-01

    Bone and tooth loss, as a result of trauma, anatomical or congenital reasons, cancer, and periodontal disease, is a common therapeutic problem in the fields of cranio-maxillo-facial surgery and periodontics. The proposed techniques for the treatment of various bone defects encountered include bone grafts, bone substitutes, guided tissue regeneration, and distraction osteogenesis as well as their combinations. In addition, dental implants have been successfully utilized for the restoration of full or partial edentulism. The introduction and development of new therapeutic approaches and devices demand the use of appropriate animal models that present bone anatomy and healing comparable to human. Among other animal models, the pig is extensively documented in several biomedical areas and has been largely used in maxillo-facial surgery and implants dentistry-related research. Anatomical and physiological similarities with human in size, physiology, and bone biology contribute to a successful involvement of this animal to understand and treat various osseous lesions. However, improvements and standardization are requested with respect to consistency and discrimination abilities. The aim of this review is to provide a critical appraisal of the literature related to swine models for the evaluation of cranio-maxillo-facial osseous defect healing, regeneration, and bone-implant interface. This review should assist researchers in the field to select the most appropriate model for each dedicated purpose and also contribute to stimulate an innovative thinking on the use of porcine models.

  11. Morphological studies at subchondral bone structures in human early arthrosis. Final report

    International Nuclear Information System (INIS)

    1992-01-01

    Quantitative histomorphometric studies using an image analysis system were performed simultaneously on hyaline cartilage, calcified cartilage and subchondral cancellous bone of human tibial heads for detailed information about the pathogenesis of arthrosis. Joint structures need to be fully detected in three dimensions since measurement values are more affected by topographical aspects than by either age, or sex, or arthrosin stage. Mechanical factors were found to affect essentially the initiation and progression of arthrosis. Results are demonstrated in detail. (orig.) [de

  12. Characterization of a rat model of metastatic prostate cancer bone pain

    Directory of Open Access Journals (Sweden)

    Paolo Donato De Ciantis

    2010-11-01

    Full Text Available Paolo Donato De Ciantis1, Kiran Yashpal2, James Henry3, Gurmit Singh11Department of Pathology and Molecular Pathology, 2Pain Research Laboratories, 3Department of Psychiatry and Behavioral Neurosciences, McMaster University, Hamilton, Ontario, CanadaPurpose: The objectives of this study were to establish and characterize a novel animal model of metastatic prostate cancer-induced bone pain.Methods: Copenhagen rats were injected with 106 MATLyLu (MLL prostate cancer cells or phosphate-buffered saline by per cutaneous intra femoral injections into the right hind leg distal epiphysis. Over 13 days, rats progressively developed a tumor within the distal femoral epiphysis. On days 3, 7, 10, and 13 post injection, rats were subjected to the incapacitance and Randall–Selitto behavioral tests as they are believed to be indirect reflections of tumor induced pain. Ipsilateral hind limbs were subjected to X-ray and computed tomography (CT scans and histological sections were stained with hematoxylin and eosin (H&E.Results: Intra femoral injections of MLL cells resulted in the progressive development of a tumor leading to bone destruction and nociceptive behaviors. Tumor development resulted in the redistribution of weight to the contralateral hind leg and significantly reduced the paw withdrawal threshold of the ipsilateral hind paw as observed via the incapacitance and Randall–Selitto tests, respectively. X-ray and computed tomography scans along with H&E stains indicated tumor-associated structural damage to the distal femur. This model was challenged with administration of meloxicam. Compared with vehicle-injected controls, the meloxicam-treated rats displayed smaller nociceptive responses as observed with the incapacitance and Randall–Selitto tests, suggesting that meloxicam was effective in reducing the pain-related symptoms displayed by model animals and that the model behaved in a predictable way to cyclooxygenase-2 treatment.Conclusions: This

  13. Study on bone mineral density and bone structure of lumbar vertebrae in osteoporotic elderly women with multi-slice CT

    International Nuclear Information System (INIS)

    Wu Shengyong; Qi Ji; Wang Bin; Wen Lianqing

    2005-01-01

    Objective: To evaluate the ability of volumetric bone mineral density (BMD) parameters of lumbar vertebrae in differentiating osteoporotic fractured from nonfractured elderly women with vQCT technique, and to compare the bony structural conditions of osteoporotic elderly women with healthy elderly women. Methods: Multi-slice CT spinal scans of L1 and L2 were acquired in 26 osteoporotic vertebral fractured elderly women (group one) and 30 nonfractured osteoporotic subjects (group two). All the retro-reconstructed images of L1 and L2 were sent to the workstation and processed by volume rendering (VR) technique to measure volumetric BMD (3D-INTGL, 3D-CORT, 3D-TRAB) and trabecular and integral BMD (2D-TRAB, 2D-INTGL) by conventional QCT technique. BMD indexes in DXA were AP-SPINE and bone mineral apparent density (BMAD) in anteroposterior position. The seven parameters between the two group s were compared. Ten healthy elderly women were selected as normal group to reformate 3D-VR images from MSCT images to analyze the bony structure and calculate the ratio of bone volume to total volume (BV/TV) in the center of L1 vertebrae, and to compare the index between the normal group and tenpatients randomly selected from the 56 osteoporotic women. Results: DXA measurements in group one: AP-SPINE and BMAD were (0.796±0.170)g/cm 2 and (272.7±27.7) mg/cm 3 , respectively, showing no statistically significant differences comparing with (0.817±0.140) g/cm 2 and (249.5 ± 26.5) mg/cm 3 in group two. Volumetric BMD in group one included 2D-TRAB (70.4 ± 22.2) mg/cm 3 , 2D-INTGL (138.3±35.1) mg/cm 3 , 3D-INTGL (139.4±34.9 ) mg/cm 3 , 3D-CORT (133.8±26.9) mg/cm 3 , and 3D-TRAB (69.9 ±18.6) mg/cm 3 , respectively, showing statistically differences with (89.1±21.8) mg/cm 3 , (170.6±34.5) mg/cm 3 , (180.5±28.2) mg/cm 3 , (163.2±27.5) mg/cm 3 , and (83.8 ± 17.1) mg/cm 3 in group two (the decrements 18%-23%). The mean value of BV/TV of L1 vertebrae was (8.12 ± 1.96)% in

  14. Testing the Hypothesis of Biofilm as a Source for Soft Tissue and Cell-Like Structures Preserved in Dinosaur Bone

    Science.gov (United States)

    2016-01-01

    Recovery of still-soft tissue structures, including blood vessels and osteocytes, from dinosaur bone after demineralization was reported in 2005 and in subsequent publications. Despite multiple lines of evidence supporting an endogenous source, it was proposed that these structures arose from contamination from biofilm-forming organisms. To test the hypothesis that soft tissue structures result from microbial invasion of the fossil bone, we used two different biofilm-forming microorganisms to inoculate modern bone fragments from which organic components had been removed. We show fundamental morphological, chemical and textural differences between the resultant biofilm structures and those derived from dinosaur bone. The data do not support the hypothesis that biofilm-forming microorganisms are the source of these structures. PMID:26926069

  15. Testing the Hypothesis of Biofilm as a Source for Soft Tissue and Cell-Like Structures Preserved in Dinosaur Bone.

    Science.gov (United States)

    Schweitzer, Mary Higby; Moyer, Alison E; Zheng, Wenxia

    2016-01-01

    Recovery of still-soft tissue structures, including blood vessels and osteocytes, from dinosaur bone after demineralization was reported in 2005 and in subsequent publications. Despite multiple lines of evidence supporting an endogenous source, it was proposed that these structures arose from contamination from biofilm-forming organisms. To test the hypothesis that soft tissue structures result from microbial invasion of the fossil bone, we used two different biofilm-forming microorganisms to inoculate modern bone fragments from which organic components had been removed. We show fundamental morphological, chemical and textural differences between the resultant biofilm structures and those derived from dinosaur bone. The data do not support the hypothesis that biofilm-forming microorganisms are the source of these structures.

  16. Testing the Hypothesis of Biofilm as a Source for Soft Tissue and Cell-Like Structures Preserved in Dinosaur Bone.

    Directory of Open Access Journals (Sweden)

    Mary Higby Schweitzer

    Full Text Available Recovery of still-soft tissue structures, including blood vessels and osteocytes, from dinosaur bone after demineralization was reported in 2005 and in subsequent publications. Despite multiple lines of evidence supporting an endogenous source, it was proposed that these structures arose from contamination from biofilm-forming organisms. To test the hypothesis that soft tissue structures result from microbial invasion of the fossil bone, we used two different biofilm-forming microorganisms to inoculate modern bone fragments from which organic components had been removed. We show fundamental morphological, chemical and textural differences between the resultant biofilm structures and those derived from dinosaur bone. The data do not support the hypothesis that biofilm-forming microorganisms are the source of these structures.

  17. Targeting the LRP5 pathway improves bone properties in a mouse model of osteogenesis imperfecta.

    Science.gov (United States)

    Jacobsen, Christina M; Barber, Lauren A; Ayturk, Ugur M; Roberts, Heather J; Deal, Lauren E; Schwartz, Marissa A; Weis, MaryAnn; Eyre, David; Zurakowski, David; Robling, Alexander G; Warman, Matthew L

    2014-10-01

    The cell surface receptor low-density lipoprotein receptor-related protein 5 (LRP5) is a key regulator of bone mass and bone strength. Heterozygous missense mutations in LRP5 cause autosomal dominant high bone mass (HBM) in humans by reducing binding to LRP5 by endogenous inhibitors, such as sclerostin (SOST). Mice heterozygous for a knockin allele (Lrp5(p.A214V) ) that is orthologous to a human HBM-causing mutation have increased bone mass and strength. Osteogenesis imperfecta (OI) is a skeletal fragility disorder predominantly caused by mutations that affect type I collagen. We tested whether the LRP5 pathway can be used to improve bone properties in animal models of OI. First, we mated Lrp5(+/p.A214V) mice to Col1a2(+/p.G610C) mice, which model human type IV OI. We found that Col1a2(+/p.G610C) ;Lrp5(+/p.A214V) offspring had significantly increased bone mass and strength compared to Col1a2(+/p.G610C) ;Lrp5(+/+) littermates. The improved bone properties were not a result of altered mRNA expression of type I collagen or its chaperones, nor were they due to changes in mutant type I collagen secretion. Second, we treated Col1a2(+/p.G610C) mice with a monoclonal antibody that inhibits sclerostin activity (Scl-Ab). We found that antibody-treated mice had significantly increased bone mass and strength compared to vehicle-treated littermates. These findings indicate increasing bone formation, even without altering bone collagen composition, may benefit patients with OI. © 2014 American Society for Bone and Mineral Research.

  18. BONE ALLOGRAFTING IN REVISION KNEE ARTHROPLASTY: HISTOLOGICAL CHARACTERISTICS OF STRUCTURAL ALLOGRAFTS 54 MONTHS FOLLOW UP

    Directory of Open Access Journals (Sweden)

    T. A. Kuliaba

    2016-01-01

    Full Text Available Compensation of large bone defects by AORI third type classification is the most difficult problem the audit knee arthroplasty. In this situation, the surgeon have to choose between three possibilities: to use metal cones/sleeves, and, in cases with severely damaged metaepiphysis, to use structural allografts or oncological megaimplants. No doubt, it is interesting to follow the processes that are taking place with massive structural allografts implanted into the human body long time ago. This article presents the case study of the rheumatoid arthritis patient’s treatment with a severe lesion of the knee joint, subjected to repeated revision surgeries, last two of which are made with the use of massive structural allograft of femur. Morphological study of a massive distal femur allograft in 54 months after surgery showed that superficial ingrowth of connective tissue and blood vessels happens on the allograft’s border with its partial restructuring of the bone tissue at the border with the recipient bone. However, the most of allograft remains unchanged even after 54 months after surgery.

  19. Preservation of bone mass and structure in hibernating black bears (Ursus americanus) through elevated expression of anabolic genes.

    Science.gov (United States)

    Fedorov, Vadim B; Goropashnaya, Anna V; Tøien, Øivind; Stewart, Nathan C; Chang, Celia; Wang, Haifang; Yan, Jun; Showe, Louise C; Showe, Michael K; Donahue, Seth W; Barnes, Brian M

    2012-06-01

    Physical inactivity reduces mechanical load on the skeleton, which leads to losses of bone mass and strength in non-hibernating mammalian species. Although bears are largely inactive during hibernation, they show no loss in bone mass and strength. To obtain insight into molecular mechanisms preventing disuse bone loss, we conducted a large-scale screen of transcriptional changes in trabecular bone comparing winter hibernating and summer non-hibernating black bears using a custom 12,800 probe cDNA microarray. A total of 241 genes were differentially expressed (P 1.4) in the ilium bone of bears between winter and summer. The Gene Ontology and Gene Set Enrichment Analysis showed an elevated proportion in hibernating bears of overexpressed genes in six functional sets of genes involved in anabolic processes of tissue morphogenesis and development including skeletal development, cartilage development, and bone biosynthesis. Apoptosis genes demonstrated a tendency for downregulation during hibernation. No coordinated directional changes were detected for genes involved in bone resorption, although some genes responsible for osteoclast formation and differentiation (Ostf1, Rab9a, and c-Fos) were significantly underexpressed in bone of hibernating bears. Elevated expression of multiple anabolic genes without induction of bone resorption genes, and the down regulation of apoptosis-related genes, likely contribute to the adaptive mechanism that preserves bone mass and structure through prolonged periods of immobility during hibernation.

  20. Assessing vertebral fracture risk on volumetric quantitative computed tomography by geometric characterization of trabecular bone structure

    Science.gov (United States)

    Checefsky, Walter A.; Abidin, Anas Z.; Nagarajan, Mahesh B.; Bauer, Jan S.; Baum, Thomas; Wismüller, Axel

    2016-03-01

    The current clinical standard for measuring Bone Mineral Density (BMD) is dual X-ray absorptiometry, however more recently BMD derived from volumetric quantitative computed tomography has been shown to demonstrate a high association with spinal fracture susceptibility. In this study, we propose a method of fracture risk assessment using structural properties of trabecular bone in spinal vertebrae. Experimental data was acquired via axial multi-detector CT (MDCT) from 12 spinal vertebrae specimens using a whole-body 256-row CT scanner with a dedicated calibration phantom. Common image processing methods were used to annotate the trabecular compartment in the vertebral slices creating a circular region of interest (ROI) that excluded cortical bone for each slice. The pixels inside the ROI were converted to values indicative of BMD. High dimensional geometrical features were derived using the scaling index method (SIM) at different radii and scaling factors (SF). The mean BMD values within the ROI were then extracted and used in conjunction with a support vector machine to predict the failure load of the specimens. Prediction performance was measured using the root-mean-square error (RMSE) metric and determined that SIM combined with mean BMD features (RMSE = 0.82 +/- 0.37) outperformed MDCT-measured mean BMD (RMSE = 1.11 +/- 0.33) (p < 10-4). These results demonstrate that biomechanical strength prediction in vertebrae can be significantly improved through the use of SIM-derived texture features from trabecular bone.

  1. Petrous bone fracture: a virtual trauma analysis.

    Science.gov (United States)

    Montava, Marion; Deveze, Arnaud; Arnoux, Pierre-Jean; Bidal, Samuel; Brunet, Christian; Lavieille, Jean-Pierre

    2012-06-01

    The temporal bone shields sensorineural, nervous, and vascular structures explaining the potential severity and complications of trauma related to road and sport accidents. So far, no clear data are available on the exact mechanisms involved for fracture processes. Modelization of structures helps to answer these concerns. Our objective was to design a finite element model of the petrous bone structure to modelize temporal bone fracture propagation in a scenario of lateral impact. A finite element model of the petrous bone structure was designed based on computed tomography data. A 7-m/s lateral impact was simulated to reproduce a typical lateral trauma. Results of model analysis was based on force recorded, stress level on bone structure up to induce a solution of continuity of the bony structure. Model simulation showed that bone fractures follow the main axes of the petrous bone and occurred in a 2-step process: first, a crush, and second, a massive fissuration of the petrous bone. The lines of fracture obtained by simulation of a lateral impact converge toward the middle ear region. This longitudinal fracture is located at the mastoid-petrous pyramid junction. Using this model, it was possible to map petrous bone fractures including fracture chronology and areas of fusion of the middle ear region. This technique may represent a first step to investigate the pathophysiology of the petrous bone fractures, aiming to define prognostic criteria for patients' care.

  2. Chronic lead poisoning magnifies bone detrimental effects in an ovariectomized rat model of postmenopausal osteoporosis.

    Science.gov (United States)

    Lee, Ching Ming; Terrizzi, Antonela Romina; Bozzini, Clarisa; Piñeiro, Adriana Emilce; Conti, María Inés; Martínez, María Pilar

    2016-01-01

    Lead (Pb) is a persistent environmental contaminant that is mainly stored in bones being an important source of endogenous lead exposure during periods of increased bone resorption as occurs in menopause. As no evidence exists of which bone biomechanical properties are impaired in those elderly women who had been exposed to Pb during their lifetime, the aim of the present study is to discern whether chronic lead poisoning magnifies the deterioration of bone biology that occurs in later stages of life. We investigated the effect of Pb in the femora of ovariectomized (OVX) female Wistar rats who had been intoxicated with 1000 ppm of Pb acetate in drinking water for 8 months. Structural properties were determined using a three-point bending mechanical test, and geometrical and material properties were evaluated after obtaining the load/deformation curve. Areal Bone Mineral Density (BMD) was estimated using a bone densitometer. Femoral histomorphometry was carried out on slices dyed with H&E (Hematoxylin and Eosin). Pb and OVX decreased all structural properties with a higher effect when both treatments were applied together. Medullar and cortical area of femurs under OVX increased, allowing the bone to accommodate its architecture, which was not observed under Pb intoxication. Pb and OVX significantly decreased BMD, showing lead treated ovariectomized rats (PbOVX) animals the lowest BMD levels. Trabecular bone volume per total volume (BV/TV%) was decreased in OVX and PbOVX animals in 54% compared to the control animals (p<0.001). Pb femurs also showed 28% less trabeculae than the control (p<0.05). We demonstrated that Pb intoxication magnifies the impairment in bone biomechanics of OVX rats with a consequent enhancement of the risk of fracture. These results enable the discussion of the detrimental effects of lead intoxication in bone biology in elderly women. Copyright © 2015 Elsevier GmbH. All rights reserved.

  3. Modelling the temperature evolution of bone under high intensity focused ultrasound

    Science.gov (United States)

    ten Eikelder, H. M. M.; Bošnački, D.; Elevelt, A.; Donato, K.; Di Tullio, A.; Breuer, B. J. T.; van Wijk, J. H.; van Dijk, E. V. M.; Modena, D.; Yeo, S. Y.; Grüll, H.

    2016-02-01

    Magnetic resonance-guided high intensity focused ultrasound (MR-HIFU) has been clinically shown to be effective for palliative pain management in patients suffering from skeletal metastasis. The underlying mechanism is supposed to be periosteal denervation caused by ablative temperatures reached through ultrasound heating of the cortex. The challenge is exact temperature control during sonication as MR-based thermometry approaches for bone tissue are currently not available. Thus, in contrast to the MR-HIFU ablation of soft tissue, a thermometry feedback to the HIFU is lacking, and the treatment of bone metastasis is entirely based on temperature information acquired in the soft tissue adjacent to the bone surface. However, heating of the adjacent tissue depends on the exact sonication protocol and requires extensive modelling to estimate the actual temperature of the cortex. Here we develop a computational model to calculate the spatial temperature evolution in bone and the adjacent tissue during sonication. First, a ray-tracing technique is used to compute the heat production in each spatial point serving as a source term for the second part, where the actual temperature is calculated as a function of space and time by solving the Pennes bio-heat equation. Importantly, our model includes shear waves that arise at the bone interface as well as all geometrical considerations of transducer and bone geometry. The model was compared with a theoretical approach based on the far field approximation and an MR-HIFU experiment using a bone phantom. Furthermore, we investigated the contribution of shear waves to the heat production and resulting temperatures in bone. The temperature evolution predicted by our model was in accordance with the far field approximation and agreed well with the experimental data obtained in phantoms. Our model allows the simulation of the HIFU treatments of bone metastasis in patients and can be extended to a planning tool prior to MR

  4. Modelling the temperature evolution of bone under high intensity focused ultrasound

    International Nuclear Information System (INIS)

    Ten Eikelder, H M M; Bošnački, D; Breuer, B J T; Van Wijk, J H; Van Dijk, E V M; Modena, D; Yeo, S Y; Grüll, H; Elevelt, A; Donato, K; Di Tullio, A

    2016-01-01

    Magnetic resonance-guided high intensity focused ultrasound (MR-HIFU) has been clinically shown to be effective for palliative pain management in patients suffering from skeletal metastasis. The underlying mechanism is supposed to be periosteal denervation caused by ablative temperatures reached through ultrasound heating of the cortex. The challenge is exact temperature control during sonication as MR-based thermometry approaches for bone tissue are currently not available. Thus, in contrast to the MR-HIFU ablation of soft tissue, a thermometry feedback to the HIFU is lacking, and the treatment of bone metastasis is entirely based on temperature information acquired in the soft tissue adjacent to the bone surface. However, heating of the adjacent tissue depends on the exact sonication protocol and requires extensive modelling to estimate the actual temperature of the cortex. Here we develop a computational model to calculate the spatial temperature evolution in bone and the adjacent tissue during sonication. First, a ray-tracing technique is used to compute the heat production in each spatial point serving as a source term for the second part, where the actual temperature is calculated as a function of space and time by solving the Pennes bio-heat equation. Importantly, our model includes shear waves that arise at the bone interface as well as all geometrical considerations of transducer and bone geometry. The model was compared with a theoretical approach based on the far field approximation and an MR-HIFU experiment using a bone phantom. Furthermore, we investigated the contribution of shear waves to the heat production and resulting temperatures in bone. The temperature evolution predicted by our model was in accordance with the far field approximation and agreed well with the experimental data obtained in phantoms. Our model allows the simulation of the HIFU treatments of bone metastasis in patients and can be extended to a planning tool prior to MR

  5. Topical Treatment with Xiaozheng Zhitong Paste (XZP Alleviates Bone Destruction and Bone Cancer Pain in a Rat Model of Prostate Cancer-Induced Bone Pain by Modulating the RANKL/RANK/OPG Signaling

    Directory of Open Access Journals (Sweden)

    Yanju Bao

    2015-01-01

    Full Text Available To explore the effects and mechanisms of Xiaozheng Zhitong Paste (XZP on bone cancer pain, Wistar rats were inoculated with vehicle or prostate cancer PC-3 into the tibia bone and treated topically with inert paste, XZP at 15.75, 31.5, or 63 g/kg twice per day for 21 days. Their bone structural damage, nociceptive behaviors, bone osteoclast and osteoblast activity, and the levels of OPG, RANL, RNAK, PTHrP, IGF-1, M-CSF, IL-8, and TNF-α were examined. In comparison with that in the placebo group, significantly reduced numbers of invaded cancer cells, decreased levels of bone damage and mechanical threshold and paw withdrawal latency, lower levels of serum TRACP5b, ICTP, PINP, and BAP, and less levels of bone osteoblast and osteoclast activity were detected in the XZP-treated rats (P<0.05. Moreover, significantly increased levels of bone OPG but significantly decreased levels of RANL, RNAK, PTHrP, IGF-1, M-CSF, IL-8, and TNF-α were detected in the XZP-treated rats (P<0.05 for all. Together, XZP treatment significantly mitigated the cancer-induced bone damage and bone osteoclast and osteoblast activity and alleviated prostate cancer-induced bone pain by modulating the RANKL/RANK/OPG pathway and bone cancer-related inflammation in rats.

  6. Influence of Orthotropy on Biomechanics of Peri-Implant Bone in Complete Mandible Model with Full Dentition

    Directory of Open Access Journals (Sweden)

    Xi Ding

    2014-01-01

    Full Text Available Objective. The study was to investigate the impact of orthotropic material on the biomechanics of dental implant, based on a detailed mandible with high geometric and mechanical similarity. Materials and Methods. Multiple data sources were used to elaborate detailed biological structures and implant CAD models. In addition, an extended orthotropic material assignment methodology based on harmonic fields was used to handle the alveolar ridge region to generate compatible orthotropic fields. The influence of orthotropic material was compared with the commonly used isotropic model and simplified orthotropic model. Results. The simulation results showed that the values of stress and strain on the implant-bone interface almost increased in the orthotropic model compared to the isotropic case, especially for the cancellous bone. However, the local stress concentration was more obvious in the isotropic case compared to that in orthotropic case. The simple orthotropic model revealed irregular stress and strain distribution, compared to the isotropic model and the real orthotropic model. The influence of orthotropy was little on the implant, periodontal ligament, tooth enamel, and dentin. Conclusion. The orthotropic material has significant effect on stress and strain of implant-bone interface in the mandible, compared with the isotropic simulation. Real orthotropic mechanical properties of mandible should be emphasized in biomechanical studies of dental implants.

  7. The Effect of Rosiglitazone on Bone Quality in a Rat Model of Insulin Resistance and Osteoporosis

    Science.gov (United States)

    Sardone, Laura Donata

    Rosiglitazone (RSG) is an insulin-sensitizing drug used to treat Type 2 Diabetes Mellitus (T2DM). Clinical trials show that women taking RSG experience more limb fractures than patients taking other T2DM drugs. The purpose of this study is to understand how RSG (3mg/kg/day and 10mg/kg/day) and the bisphosphonate alendronate (0.7mg/kg/week) alter bone quality in the male, female and female ovariectomized (OVX) Zucker fatty rat model over a 12 week period. Bone quality was evaluated by mechanical testing of cortical and trabecular bone. Microarchitecture, bone mineral density (BMD), cortical bone porosity, bone formation/resorption and mineralization were also measured. Female OVX RSG10mg/kg rats had significantly lower vertebral BMD and compromised trabecular architecture versus OVX controls. Increased cortical porosity and decreased mechanical properties occurred in these rats. ALN treatment prevented these negative effects in the OVX RSG model. Evidence of reduced bone formation and excess bone resorption was detected in female RSG-treated rats.

  8. Computational model-informed design and bioprinting of cell-patterned constructs for bone tissue engineering.

    Science.gov (United States)

    Carlier, Aurélie; Skvortsov, Gözde Akdeniz; Hafezi, Forough; Ferraris, Eleonora; Patterson, Jennifer; Koç, Bahattin; Van Oosterwyck, Hans

    2016-05-17

    Three-dimensional (3D) bioprinting is a rapidly advancing tissue engineering technology that holds great promise for the regeneration of several tissues, including bone. However, to generate a successful 3D bone tissue engineering construct, additional complexities should be taken into account such as nutrient and oxygen delivery, which is often insufficient after implantation in large bone defects. We propose that a well-designed tissue engineering construct, that is, an implant with a specific spatial pattern of cells in a matrix, will improve the healing outcome. By using a computational model of bone regeneration we show that particular cell patterns in tissue engineering constructs are able to enhance bone regeneration compared to uniform ones. We successfully bioprinted one of the most promising cell-gradient patterns by using cell-laden hydrogels with varying cell densities and observed a high cell viability for three days following the bioprinting process. In summary, we present a novel strategy for the biofabrication of bone tissue engineering constructs by designing cell-gradient patterns based on a computational model of bone regeneration, and successfully bioprinting the chosen design. This integrated approach may increase the success rate of implanted tissue engineering constructs for critical size bone defects and also can find a wider application in the biofabrication of other types of tissue engineering constructs.

  9. Advanced computational workflow for the multi-scale modeling of the bone metabolic processes.

    Science.gov (United States)

    Dao, Tien Tuan

    2017-06-01

    Multi-scale modeling of the musculoskeletal system plays an essential role in the deep understanding of complex mechanisms underlying the biological phenomena and processes such as bone metabolic processes. Current multi-scale models suffer from the isolation of sub-models at each anatomical scale. The objective of this present work was to develop a new fully integrated computational workflow for simulating bone metabolic processes at multi-scale levels. Organ-level model employs multi-body dynamics to estimate body boundary and loading conditions from body kinematics. Tissue-level model uses finite element method to estimate the tissue deformation and mechanical loading under body loading conditions. Finally, cell-level model includes bone remodeling mechanism through an agent-based simulation under tissue loading. A case study on the bone remodeling process located on the human jaw was performed and presented. The developed multi-scale model of the human jaw was validated using the literature-based data at each anatomical level. Simulation outcomes fall within the literature-based ranges of values for estimated muscle force, tissue loading and cell dynamics during bone remodeling process. This study opens perspectives for accurately simulating bone metabolic processes using a fully integrated computational workflow leading to a better understanding of the musculoskeletal system function from multiple length scales as well as to provide new informative data for clinical decision support and industrial applications.

  10. Sclerostin Antibody Treatment Improves the Bone Phenotype of Crtap(-/-) Mice, a Model of Recessive Osteogenesis Imperfecta.

    Science.gov (United States)

    Grafe, Ingo; Alexander, Stefanie; Yang, Tao; Lietman, Caressa; Homan, Erica P; Munivez, Elda; Chen, Yuqing; Jiang, Ming Ming; Bertin, Terry; Dawson, Brian; Asuncion, Franklin; Ke, Hua Zhu; Ominsky, Michael S; Lee, Brendan

    2016-05-01

    Osteogenesis imperfecta (OI) is characterized by low bone mass, poor bone quality, and fractures. Standard treatment for OI patients is limited to bisphosphonates, which only incompletely correct the bone phenotype, and seem to be less effective in adults. Sclerostin-neutralizing antibodies (Scl-Ab) have been shown to be beneficial in animal models of osteoporosis, and dominant OI resulting from mutations in the genes encoding type I collagen. However, Scl-Ab treatment has not been studied in models of recessive OI. Cartilage-associated protein (CRTAP) is involved in posttranslational type I collagen modification, and its loss of function results in recessive OI. In this study, we treated 1-week-old and 6-week-old Crtap(-/-) mice with Scl-Ab for 6 weeks (25 mg/kg, s.c., twice per week), to determine the effects on the bone phenotype in models of "pediatric" and "young adult" recessive OI. Vehicle-treated Crtap(-/-) and wild-type (WT) mice served as controls. Compared with control Crtap(-/-) mice, micro-computed tomography (μCT) analyses showed significant increases in bone volume and improved trabecular microarchitecture in Scl-Ab-treated Crtap(-/-) mice in both age cohorts, in both vertebrae and femurs. Additionally, Scl-Ab improved femoral cortical parameters in both age cohorts. Biomechanical testing showed that Scl-Ab improved parameters of whole-bone strength in Crtap(-/-) mice, with more robust effects in the week 6 to 12 cohort, but did not affect the increased bone brittleness. Additionally, Scl-Ab normalized the increased osteoclast numbers, stimulated bone formation rate (week 6 to 12 cohort only), but did not affect osteocyte density. Overall, our findings suggest that Scl-Ab treatment may be beneficial in the treatment of recessive OI caused by defects in collagen posttranslational modification. © 2015 American Society for Bone and Mineral Research. © 2015 American Society for Bone and Mineral Research.

  11. Individual bone structure segmentation and labeling from low-dose chest CT

    Science.gov (United States)

    Liu, Shuang; Xie, Yiting; Reeves, Anthony P.

    2017-03-01

    The segmentation and labeling of the individual bones serve as the first step to the fully automated measurement of skeletal characteristics and the detection of abnormalities such as skeletal deformities, osteoporosis, and vertebral fractures. Moreover, the identified landmarks on the segmented bone structures can potentially provide relatively reliable location reference to other non-rigid human organs, such as breast, heart and lung, thereby facilitating the corresponding image analysis and registration. A fully automated anatomy-directed framework for the segmentation and labeling of the individual bone structures from low-dose chest CT is presented in this paper. The proposed system consists of four main stages: First, both clavicles are segmented and labeled by fitting a piecewise cylindrical envelope. Second, the sternum is segmented under the spatial constraints provided by the segmented clavicles. Third, all ribs are segmented and labeled based on 3D region growing within the volume of interest defined with reference to the spinal canal centerline and lungs. Fourth, the individual thoracic vertebrae are segmented and labeled by image intensity based analysis in the spatial region constrained by the previously segmented bone structures. The system performance was validated with 1270 lowdose chest CT scans through visual evaluation. Satisfactory performance was obtained respectively in 97.1% cases for the clavicle segmentation and labeling, in 97.3% cases for the sternum segmentation, in 97.2% cases for the rib segmentation, in 94.2% cases for the rib labeling, in 92.4% cases for vertebra segmentation and in 89.9% cases for the vertebra labeling.

  12. Observations on structural features and characteristics of biological apatite crystals. 4. Observation on ultrastructure of human bone crystals.

    Science.gov (United States)

    Ichijo, T; Yamashita, Y; Terashima, T

    1993-06-01

    In a series of studies to investigate the structural features of the biological crystals such as the tooth and bone, following the previous observations of the tooth crystal using an electron microscope, we examined the ultrastructure of the human bone crystals at near atomic resolution through the cross and longitudinal sections of the crystals. The materials used for this study were the normal bone tissue obtained from the buccal alveolar compact bone of the human mandible in the portion of the lower first molar. The small cubes of the bone tissue were fixed in glutaraldehyde and osmium tetroxide and embedded in epoxy resin using the routine methods. The ultrathin sections were cut with a diamond knife without decalcification. The sections were examined with the HITACHI H-800 type transmission electron microscope operated at 200 kV. Each crystal was observed at the initial magnification of 300,000 times and at the final magnification of 10,000,000 times and over. Using this approach, we showed the configuration of the hydroxyapatite structure in the cross and longitudinal sections of the bone crystals deposited within and between the collagen fibrils (intrafibrillar and interfibrillar crystals) in the bone tissue. Furthermore, using the same approach, we observed the crystal lattices of the hydroxyapatite structure appearing in the cross and longitudinal sections. We sincerely believe that the electron micrographs shown in this report are the first atomic images from the section obtained from the hydroxyapatite crystal from the human alveolar bone.

  13. Track structure in biological models.

    Science.gov (United States)

    Curtis, S B

    1986-01-01

    High-energy heavy ions in the galactic cosmic radiation (HZE particles) may pose a special risk during long term manned space flights outside the sheltering confines of the earth's geomagnetic field. These particles are highly ionizing, and they and their nuclear secondaries can penetrate many centimeters of body tissue. The three dimensional patterns of ionizations they create as they lose energy are referred to as their track structure. Several models of biological action on mammalian cells attempt to treat track structure or related quantities in their formulation. The methods by which they do this are reviewed. The proximity function is introduced in connection with the theory of Dual Radiation Action (DRA). The ion-gamma kill (IGK) model introduces the radial energy-density distribution, which is a smooth function characterizing both the magnitude and extension of a charged particle track. The lethal, potentially lethal (LPL) model introduces lambda, the mean distance between relevant ion clusters or biochemical species along the track. Since very localized energy depositions (within approximately 10 nm) are emphasized, the proximity function as defined in the DRA model is not of utility in characterizing track structure in the LPL formulation.

  14. Analysis of dengue fever risk using geostatistics model in bone regency

    Science.gov (United States)

    Amran, Stang, Mallongi, Anwar

    2017-03-01

    This research aim is to analysis of dengue fever risk based on Geostatistics model in Bone Regency. Risk levels of dengue fever are denoted by parameter of Binomial distribution. Effect of temperature, rainfalls, elevation, and larvae abundance are investigated through Geostatistics model. Bayesian hierarchical method is used in estimation process. Using dengue fever data in eleven locations this research shows that temperature and rainfall have significant effect of dengue fever risk in Bone regency.

  15. The computed tomography-based fractal analysis of trabecular bone structure may help in detecting decreased quality of bone before urgent spinal procedures.

    Science.gov (United States)

    Czyz, Marcin; Kapinas, Arion; Holton, James; Pyzik, Renata; Boszczyk, Bronek M; Quraishi, Nasir A

    2017-08-01

    To date, no reliable method is available to determine the parameters of bone density based on the routine spinal computed tomography (CT) in the emergency setup. We propose the use of fractal analysis to detect patients with poor quality of bone before urgent or semi-urgent spinal procedures. This study aimed to validate the hypothesis that the CT-based fractal analysis of the trabecular bone structure may help in detecting patients with poor quality of bone before urgent spinal procedures. This is a retrospective analysis of prospectively collected data. Patients in whom the dual-energy x-ray absorptiometry (DEXA) scan and lumbar spine CT were performed at an interval of no more than 3 months were randomly selected from a prospectively collected database. Diagnostic axial CT scans of L2, L3, and L4 vertebrae were processed to determine the fractal dimension (FD) of the trabecular structure of each spinal level. Box-count method and ImageJ 1.49 software were used. The FD was compared with the results of the DEXA scan: bone mineral density (BMD) and T-score by mean of correlation coefficients. Receiver operating characteristic curve analysis was later performed to determine the cutoff value of FD. A total of 102 vertebral levels obtained from 35 patients (mean age 60±18 years; 29 female) were analyzed. The FD was significantly higher in the group of patients with decreased bone density (DBD) (T-score1.53 indicates DBD (pfractal analysis of the lumbar spine CT images may be used to determine bone density before spinal instrumentation (eg, metastatic or traumatic cord compression). Further prospective studies comparing results of the fractal analysis of CT scans with quantitative CT (qCT) are warranted. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. Quantitative Evaluation of Trabecular Bone Structure by Calcaneus MR Images Texture Analysis of Healthy Volunteers and Osteoporotic Subjects

    National Research Council Canada - National Science Library

    Herlidou, S

    2001-01-01

    The aim of this study is to evaluate, in vivo, trabecular bone structure of the calcaneus of healthy volunteers and osteoporotic patients by texture analysis of MR images Automated methods of texture...

  17. Methotrexate Toxicity in Growing Long Bones of Young Rats: A Model for Studying Cancer Chemotherapy-Induced Bone Growth Defects in Children

    Directory of Open Access Journals (Sweden)

    Chiaming Fan

    2011-01-01

    Full Text Available The advancement and intensive use of chemotherapy in treating childhood cancers has led to a growing population of young cancer survivors who face increased bone health risks. However, the underlying mechanisms for chemotherapy-induced skeletal defects remain largely unclear. Methotrexate (MTX, the most commonly used antimetabolite in paediatric cancer treatment, is known to cause bone growth defects in children undergoing chemotherapy. Animal studies not only have confirmed the clinical observations but also have increased our understanding of the mechanisms underlying chemotherapy-induced skeletal damage. These models revealed that high-dose MTX can cause growth plate dysfunction, damage osteoprogenitor cells, suppress bone formation, and increase bone resorption and marrow adipogenesis, resulting in overall bone loss. While recent rat studies have shown that antidote folinic acid can reduce MTX damage in the growth plate and bone, future studies should investigate potential adjuvant treatments to reduce chemotherapy-induced skeletal toxicities.

  18. Bi-layered calcium phosphate cement-based composite scaffold mimicking natural bone structure.

    Science.gov (United States)

    He, Fupo; Ye, Jiandong

    2013-08-01

    In this study, a core/shell bi-layered calcium phosphate cement (CPC)-based composite scaffold with adjustable compressive strength, which mimicked the structure of natural cortical/cancellous bone, was fabricated. The dense tubular CPC shell was prepared by isostatic pressing CPC powder with a specially designed mould. A porous CPC core with unidirectional lamellar pore structure was fabricated inside the cavity of dense tubular CPC shell by unidirectional freeze casting, followed by infiltration of poly(lactic-co-glycolic acid) and immobilization of collagen. The compressive strength of bi-layered CPC-based composite scaffold can be controlled by varying thickness ratio of dense layer to porous layer. Compared to the scaffold without dense shell, the pore interconnection of bi-layered scaffold was not obviously compromised because of its high unidirectional interconnectivity but poor three dimensional interconnectivity. The in vitro results showed that the rat bone marrow stromal cells attached and proliferated well on the bi-layered CPC-based composite scaffold. This novel bi-layered CPC-based composite scaffold is promising for bone repair.

  19. Application of continuous-wave terahertz computed tomography for the analysis of chicken bone structure

    Science.gov (United States)

    Li, Bin; Wang, Dayong; Rong, Lu; Zhai, Changchao; Wang, Yunxin; Zhao, Jie

    2018-02-01

    Terahertz (THz) radiation is able to penetrate many different types of nonpolar and nonmetallic materials without the damaging effects of x-rays. THz technology can be combined with computed tomography (CT) to form THz CT, which is an effective imaging method that is used to visualize the internal structure of a three-dimensional sample as cross-sectional images. Here, we reported an application of THz as the radiation source in CT imaging by replacing the x-rays. In this method, the sample cross section is scanned in all translation and rotation directions. Then, the projection data are reconstructed using a tomographic reconstruction algorithm. Two-dimensional (2-D) cross-sectional images of the chicken ulna were obtained through the continuous-wave (CW) THz CT system. Given by the difference of the THz absorption of different substances, the compact bone and spongy bone inside the chicken ulna are structurally distinguishable in the 2-D cross-sectional images. Using the filtered back projection algorithm, we reconstructed the projection data of the chicken ulna at different projection angle intervals and found that the artifacts and noise in the images are strikingly increased when the projection angle intervals become larger, reflected by the blurred boundary of the compact bone. The quality and fidelity of the 2-D cross-sectional images could be substantially improved by reducing the projection angle intervals. Our experimental data demonstrated a feasible application of the CW THz CT system in biological imaging.

  20. Structure and modeling of turbulence

    International Nuclear Information System (INIS)

    Novikov, E.A.

    1995-01-01

    The open-quotes vortex stringsclose quotes scale l s ∼ LRe -3/10 (L-external scale, Re - Reynolds number) is suggested as a grid scale for the large-eddy simulation. Various aspects of the structure of turbulence and subgrid modeling are described in terms of conditional averaging, Markov processes with dependent increments and infinitely divisible distributions. The major request from the energy, naval, aerospace and environmental engineering communities to the theory of turbulence is to reduce the enormous number of degrees of freedom in turbulent flows to a level manageable by computer simulations. The vast majority of these degrees of freedom is in the small-scale motion. The study of the structure of turbulence provides a basis for subgrid-scale (SGS) models, which are necessary for the large-eddy simulations (LES)

  1. The Sealing Zone in Osteoclasts: A Self-Organized Structure on the Bone

    Directory of Open Access Journals (Sweden)

    Jiro Takito

    2018-03-01

    Full Text Available Osteoclasts form a specialized cell–matrix adhesion structure, known as the “sealing zone”, during bone resorption. The sealing zone is a dynamic actin-rich structure that defines the resorption area of the bone. The detailed dynamics and fine structure of the sealing zone have been elusive. Osteoclasts plated on glass do not form a sealing zone, but generate a separate supra-molecular structure called the “podosome belt”. Podosomes are integrin-based adhesion complexes involved in matrix adhesion, cell migration, matrix degradation, and mechanosensing. Invadopodia, podosome-like protrusions in cancer cells, are involved in cell invasion into other tissues by promoting matrix degradation. Both podosomes and invadopodia exhibit actin pattern transitions during maturation. We previously found that Arp2/3-dependent actin flow occurs in all observed assembly patterns of podosomes in osteoclasts on glass. It is known that the actin wave in Dictyostelium cells exhibits a similar pattern transition in its evolution. Because of significant advances in our understanding regarding the mechanism of podosomes/invadopodia formation over the last decade, we revisited the structure and function of the sealing zone in this review, highlighting the possible involvement of self-organized actin waves in the organogenesis of the sealing zone.

  2. The Sealing Zone in Osteoclasts: A Self-Organized Structure on the Bone.

    Science.gov (United States)

    Takito, Jiro; Inoue, Satoshi; Nakamura, Masanori

    2018-03-26

    Osteoclasts form a specialized cell-matrix adhesion structure, known as the "sealing zone", during bone resorption. The sealing zone is a dynamic actin-rich structure that defines the resorption area of the bone. The detailed dynamics and fine structure of the sealing zone have been elusive. Osteoclasts plated on glass do not form a sealing zone, but generate a separate supra-molecular structure called the "podosome belt". Podosomes are integrin-based adhesion complexes involved in matrix adhesion, cell migration, matrix degradation, and mechanosensing. Invadopodia, podosome-like protrusions in cancer cells, are involved in cell invasion into other tissues by promoting matrix degradation. Both podosomes and invadopodia exhibit actin pattern transitions during maturation. We previously found that Arp2/3-dependent actin flow occurs in all observed assembly patterns of podosomes in osteoclasts on glass. It is known that the actin wave in Dictyostelium cells exhibits a similar pattern transition in its evolution. Because of significant advances in our understanding regarding the mechanism of podosomes/invadopodia formation over the last decade, we revisited the structure and function of the sealing zone in this review, highlighting the possible involvement of self-organized actin waves in the organogenesis of the sealing zone.

  3. Geometric and mechanical properties evaluation of scaffolds for bone tissue applications designing by a reaction-diffusion models and manufactured with a material jetting system

    Directory of Open Access Journals (Sweden)

    Marco A. Velasco

    2016-10-01

    Full Text Available Scaffolds are essential in bone tissue engineering, as they provide support to cells and growth factors necessary to regenerate tissue. In addition, they meet the mechanical function of the bone while it regenerates. Currently, the multiple methods for designing and manufacturing scaffolds are based on regular structures from a unit cell that repeats in a given domain. However, these methods do not resemble the actual structure of the trabecular bone which may work against osseous tissue regeneration. To explore the design of porous structures with similar mechanical properties to native bone, a geometric generation scheme from a reaction-diffusion model and its manufacturing via a material jetting system is proposed. This article presents the methodology used, the geometric characteristics and the modulus of elasticity of the scaffolds designed and manufactured. The method proposed shows its potential to generate structures that allow to control the basic scaffold properties for bone tissue engineering such as the width of the channels and porosity. The mechanical properties of our scaffolds are similar to trabecular tissue present in vertebrae and tibia bones. Tests on the manufactured scaffolds show that it is necessary to consider the orientation of the object relative to the printing system because the channel geometry, mechanical properties and roughness are heavily influenced by the position of the surface analyzed with respect to the printing axis. A possible line for future work may be the establishment of a set of guidelines to consider the effects of manufacturing processes in designing stages.

  4. In Vitro Co-Culture Models of Breast Cancer Metastatic Progression towards Bone

    Directory of Open Access Journals (Sweden)

    Chiara Arrigoni

    2016-08-01

    Full Text Available Advanced breast cancer frequently metastasizes to bone through a multistep process involving the detachment of cells from the primary tumor, their intravasation into the bloodstream, adhesion to the endothelium and extravasation into the bone, culminating with the establishment of a vicious cycle causing extensive bone lysis. In recent years, the crosstalk between tumor cells and secondary organs microenvironment is gaining much attention, being indicated as a crucial aspect in all metastatic steps. To investigate the complex interrelation between the tumor and the microenvironment, both in vitro and in vivo models have been exploited. In vitro models have some advantages over in vivo, mainly the possibility to thoroughly dissect in controlled conditions and with only human cells the cellular and molecular mechanisms underlying the metastatic progression. In this article we will review the main results deriving from in vitro co-culture models, describing mechanisms activated in the crosstalk between breast cancer and bone cells which drive the different metastatic steps.

  5. Structural Agricultural Land Use Modelling

    OpenAIRE

    Fezzi, Carlo; Bateman, Ian J.

    2009-01-01

    This paper develops a structural econometric model of agricultural land use and production based on the joint multi-output technology representation introduced by Chambers and Just (1989). Starting from a flexible specification of the farm profit function we derive land use allocation, input applications, crops yield and livestock number equations in a joint and theoretically consistent framework. We present an empirical application using fine-scale spatial data covering the entirety of Engla...

  6. Modeling of Blood Lead Levels in Astronauts Exposed to Lead from Microgravity-Accelerated Bone Loss

    Science.gov (United States)

    Garcia, H.; James, J.; Tsuji, J.

    2014-01-01

    Human exposure to lead has been associated with toxicity to multiple organ systems. Studies of various population groups with relatively low blood lead concentrations (bones, the adverse effects of lead correlate with the concentration of lead in the blood better than with that in the bones. NASA has found that prolonged exposure to microgravity during spaceflight results in a significant loss of bone minerals, the extent of which varies from individual to individual and from bone to bone, but generally averages about 0.5% per month. During such bone loss, lead that had been stored in bones would be released along with calcium. The effects on the concentration of lead in the blood (PbB) of various concentrations of lead in drinking water (PbW) and of lead released from bones due to accelerated osteoporosis in microgravity, as well as changes in exposure to environmental lead before, during, and after spaceflight were evaluated using a physiologically based pharmacokinetic (PBPK) model that incorporated exposure to environmental lead both on earth and in flight and included temporarily increased rates of osteoporosis during spaceflight.

  7. Quantitative Evaluation of Trabecular Bone Structure by Calcaneus MR Images Texture Analysis of Healthy Volunteers and Osteoporotic Subjects

    Science.gov (United States)

    2001-10-25

    purpose is to set up a calcaneus architecture analysis by MRI that could be used routinely to improve fracture risk prediction and to assess anti...1 of 3 QUANTITATIVE EVALUATION OF TRABECULAR BONE STRUCTURE BY CALCANEUS MR IMAGES TEXTURE ANALYSIS OF HEALTHY VOLUNTEERS AND OSTEOPOROTIC...Picardie Jules Verne, Amiens, FRANCE Abstract - The aim of this study is to evaluate, in vivo, trabecular bone structure of the calcaneus of healthy

  8. Culturing bone marrow cells with dexamethasone and ascorbic acid improves osteogenic cell sheet structure.

    Science.gov (United States)

    Akahane, M; Shimizu, T; Kira, T; Onishi, T; Uchihara, Y; Imamura, T; Tanaka, Y

    2016-11-01

    To assess the structure and extracellular matrix molecule expression of osteogenic cell sheets created via culture in medium with both dexamethasone (Dex) and ascorbic acid phosphate (AscP) compared either Dex or AscP alone. Osteogenic cell sheets were prepared by culturing rat bone marrow stromal cells in a minimal essential medium (MEM), MEM with AscP, MEM with Dex, and MEM with Dex and AscP (Dex/AscP). The cell number and messenger (m)RNA expression were assessed in vitro, and the appearance of the cell sheets was observed after mechanical retrieval using a scraper. β-tricalcium phosphate (β-TCP) was then wrapped with the cell sheets from the four different groups and subcutaneously implanted into rats. After mechanical retrieval, the osteogenic cell sheets from the MEM, MEM with AscP, and MEM with Dex groups appeared to be fragmented or incomplete structures. The cell sheets cultured with Dex/AscP remained intact after mechanical retrieval, without any identifiable tears. Culture with Dex/AscP increased the mRNA and protein expression of extracellular matrix proteins and cell number compared with those of the other three groups. More bridging bone formation was observed after transplantation of the β-TCP scaffold wrapped with cell sheets cultured with Dex/AscP, than in the other groups. These results suggest that culture with Dex/AscP improves the mechanical integrity of the osteogenic cell sheets, allowing retrieval of the confluent cells in a single cell sheet structure. This method may be beneficial when applied in cases of difficult tissue reconstruction, such as nonunion, bone defects, and osteonecrosis.Cite this article: M. Akahane, T. Shimizu, T. Kira, T. Onishi, Y. Uchihara, T. Imamura, Y. Tanaka. Culturing bone marrow cells with dexamethasone and ascorbic acid improves osteogenic cell sheet structure. Bone Joint Res 2016;5:569-576. DOI: 10.1302/2046-3758.511.BJR-2016-0013.R1. © 2016 Akahane et al.

  9. Modelling of Cortical Bone Tissue as a Fluid Saturated Double-Porous Material - Parametric Study

    Directory of Open Access Journals (Sweden)

    Jana TURJANICOVÁ

    2013-06-01

    Full Text Available In this paper, the cortical bone tissue is considered as a poroelastic material with periodic structure represented at microscopic and mesoscopic levels. The pores of microscopic scale are connected with the pores of mesoscopic scale creating one system of connected network filled with compressible fluid. The method of asymptotic homogenization is applied to upscale the microscopic model of the fluid-solid interaction under a static loading. Obtained homogenized coefficients describe material properties of the poroelastic matrix fractured by fluid-filled pores whose geometry is described at the mesoscopic level. The second-level upscaling provides homogenized poroelastic coefficients relevant on the macroscopic scale. Furthermore, we study the dependence of these coefficients on geometrical parameters on related microscopic and macroscopic scales.

  10. Statistical Modeling of Shape and Motion of the Wrist Bones

    NARCIS (Netherlands)

    Van de Giessen, M.

    2011-01-01

    Carpal instability occurs when the wrist bones assume a pathological posture, e.g. due to ligament rupture as a result of trauma. Ligament rupture cannot be diagnosed reliably directly, as current medical imaging modalities do not provide sufficient soft-tissue contrast (X-ray, CT) or lack a

  11. Electron Microscopy and Analytical X-ray Characterization of Compositional and Nanoscale Structural Changes in Fossil Bone

    Science.gov (United States)

    Boatman, Elizabeth Marie

    The nanoscale structure of compact bone contains several features that are direct indicators of bulk tissue mechanical properties. Fossil bone tissues represent unique opportunities to understand the compact bone structure/property relationships from a deep time perspective, offering a possible array of new insights into bone diseases, biomimicry of composite materials, and basic knowledge of bioapatite composition and nanoscale bone structure. To date, most work with fossil bone has employed microscale techniques and has counter-indicated the survival of bioapatite and other nanoscale structural features. The obvious disconnect between the use of microscale techniques and the discernment of nanoscale structure has prompted this work. The goal of this study was to characterize the nanoscale constituents of fossil compact bone by applying a suite of diffraction, microscopy, and spectrometry techniques, representing the highest levels of spatial and energy resolution available today, and capable of complementary structural and compositional characterization from the micro- to the nanoscale. Fossil dinosaur and crocodile long bone specimens, as well as modern ratite and crocodile femurs, were acquired from the UC Museum of Paleontology. Preserved physiological features of significance were documented with scanning electron microscopy back-scattered imaging. Electron microprobe wavelength-dispersive X-ray spectroscopy (WDS) revealed fossil bone compositions enriched in fluorine with a complementary loss of oxygen. X-ray diffraction analyses demonstrated that all specimens were composed of apatite. Transmission electron microscopy (TEM) imaging revealed preserved nanocrystallinity in the fossil bones and electron diffraction studies further identified these nanocrystallites as apatite. Tomographic analyses of nanoscale elements imaged by TEM and small angle X-ray scattering were performed, with the results of each analysis further indicating that nanoscale structure is

  12. Evaluation of injectable silica-embedded nanohydroxyapatite bone substitute in a rat tibia defect model

    Directory of Open Access Journals (Sweden)

    Xu W

    2011-08-01

    Full Text Available Weiguo Xu1, Cornelia Ganz2, Ulf Weber2, Martin Adam2, Gerd Holzhüter2, Daniel Wolter3, Bernhard Frerich3, Brigitte Vollmar1, Thomas Gerber21Institute for Experimental Surgery, 2Institute of Physics, 3Department of Oral, Maxillofacial and Plastic Surgery, University of Rostock, Rostock, GermanyAbstract: In clinical practice, vertebral compression fractures occur after trauma and osteoporosis. Kyphoplasty is a minimally invasive procedure using bone filler material for the treatment of such fractures. A full synthetic injectable bone substitute (SIBS was manufactured by means of spray drying. The aim of this study was to characterize the SIBS and to analyze the remodelling process during degradation of the biomaterial and new bone formation after implantation. SIBS is an aqueous suspension of donut-like microparticles. These microparticles consist of nanocrystallites of synthetic hydroxyapatite embedded in amorphous silica gel. After implantation of SIBS in a proximal tibial diaphyseal defect in 52 rats, grafts were harvested for subsequent analysis on different days. Newly formed bone originating from endosteum was observed on day 6. Hematomas in the medullary space and cortical wounds disappeared on day 12. The wound region was completely replaced by a composite of newly formed cancellous bone, extracellular matrix, and SIBS. At day 63 the cortical defect was fully healed by bone, while newly formed bone in the medullary space almost disappeared and was replaced with bone marrow. In conclusion, SIBS demonstrated a unique structure with osteoinductive and bioresorbable properties, which induced fast bone regeneration. Therefore, a clinical application of SIBS for kyphoplasty is promising.Keywords: bone remodelling, electron microscopy, histomorphometry, nanotechnology, tissue engineering

  13. Bone Structure and Estimated Bone Strength in Obese Patients Evaluated by High-Resolution Peripheral Quantitative Computed Tomography

    DEFF Research Database (Denmark)

    Andersen, Stine; Frederiksen, Katrine Diemer; Hansen, Stinus

    2014-01-01

    Obesity is associated with high bone mineral density (BMD), but whether obesity-related higher bone mass increases bone strength and thereby protect against fractures is uncertain. We estimated effects of obesity on bone microarchitecture and estimated strength in 36 patients (12 males and 24...... females, age 25-56 years and BMI 33.2-57.6 kg/m(2)) matched with healthy controls (age 25-54 years and BMI 19.5-24.8 kg/m(2)) in regard to gender, menopausal status, age (±6 years) and height (±6 cm) using high resolution peripheral quantitative computed tomography and dual energy X-ray absorptiometry...... patients compared with controls in radius and tibia with higher trabecular number (p = 0.002 and p estimated failure load (FL) was higher in tibia (p

  14. Correlations Between Bone Mechanical Properties and Bone Composition Parameters in Mouse Models of Dominant and Recessive Osteogenesis Imperfecta and the Response to Anti-TGF-β Treatment.

    Science.gov (United States)

    Bi, Xiaohong; Grafe, Ingo; Ding, Hao; Flores, Rene; Munivez, Elda; Jiang, Ming Ming; Dawson, Brian; Lee, Brendan; Ambrose, Catherine G

    2017-02-01

    Osteogenesis imperfecta (OI) is a group of genetic disorders characterized by brittle bones that are prone to fracture. Although previous studies in animal models investigated the mechanical properties and material composition of OI bone, little work has been conducted to statistically correlate these parameters to identify key compositional contributors to the impaired bone mechanical behaviors in OI. Further, although increased TGF-β signaling has been demonstrated as a contributing mechanism to the bone pathology in OI models, the relationship between mechanical properties and bone composition after anti-TGF-β treatment in OI has not been studied. Here, we performed follow-up analyses of femurs collected in an earlier study from OI mice with and without anti-TGF-β treatment from both recessive (Crtap -/- ) and dominant (Col1a2 +/P.G610C ) OI mouse models and WT mice. Mechanical properties were determined using three-point bending tests and evaluated for statistical correlation with molecular composition in bone tissue assessed by Raman spectroscopy. Statistical regression analysis was conducted to determine significant compositional determinants of mechanical integrity. Interestingly, we found differences in the relationships between bone composition and mechanical properties and in the response to anti-TGF-β treatment. Femurs of both OI models exhibited increased brittleness, which was associated with reduced collagen content and carbonate substitution. In the Col1a2 +/P.G610C femurs, reduced hydroxyapatite crystallinity was also found to be associated with increased brittleness, and increased mineral-to-collagen ratio was correlated with increased ultimate strength, elastic modulus, and bone brittleness. In both models of OI, regression analysis demonstrated that collagen content was an important predictor of the increased brittleness. In summary, this work provides new insights into the relationships between bone composition and material properties in

  15. Characterizing trabecular bone structure for assessing vertebral fracture risk on volumetric quantitative computed tomography

    Science.gov (United States)

    Nagarajan, Mahesh B.; Checefsky, Walter A.; Abidin, Anas Z.; Tsai, Halley; Wang, Xixi; Hobbs, Susan K.; Bauer, Jan S.; Baum, Thomas; Wismüller, Axel

    2015-03-01

    While the proximal femur is preferred for measuring bone mineral density (BMD) in fracture risk estimation, the introduction of volumetric quantitative computed tomography has revealed stronger associations between BMD and spinal fracture status. In this study, we propose to capture properties of trabecular bone structure in spinal vertebrae with advanced second-order statistical features for purposes of fracture risk assessment. For this purpose, axial multi-detector CT (MDCT) images were acquired from 28 spinal vertebrae specimens using a whole-body 256-row CT scanner with a dedicated calibration phantom. A semi-automated method was used to annotate the trabecular compartment in the central vertebral slice with a circular region of interest (ROI) to exclude cortical bone; pixels within were converted to values indicative of BMD. Six second-order statistical features derived from gray-level co-occurrence matrices (GLCM) and the mean BMD within the ROI were then extracted and used in conjunction with a generalized radial basis functions (GRBF) neural network to predict the failure load of the specimens; true failure load was measured through biomechanical testing. Prediction performance was evaluated with a root-mean-square error (RMSE) metric. The best prediction performance was observed with GLCM feature `correlation' (RMSE = 1.02 ± 0.18), which significantly outperformed all other GLCM features (p < 0.01). GLCM feature correlation also significantly outperformed MDCTmeasured mean BMD (RMSE = 1.11 ± 0.17) (p< 10-4). These results suggest that biomechanical strength prediction in spinal vertebrae can be significantly improved through characterization of trabecular bone structure with GLCM-derived texture features.

  16. Evaluation of Clinical Results and Complications of Structural Allograft Reconstruction after Bone Tumor Surgery

    Directory of Open Access Journals (Sweden)

    Mohammad Gharedaghi

    2016-07-01

    cases of infection occurred in the adjuvant chemotherapy plus radiation therapy group. Allograft fracture occurred in six patients and prevalence was the same in all groups. Only in six cases of radio-chemotherapy nonunion occurred, so we used autogenous bone graft for union. Local recurrence was observed in six patients: three belonged to the adjuvant chemotherapy group and the other three were in the chemo-radiotherapy group; no significant difference was observed between these two groups. However, there was a significant difference between these two and the group that received no adjuvant therapy. Also, there were 11 cases of metastases and Restriction of knee joint motion occurred in 48 cases of osteo-cartilaginous grafts of the distal femur and proximal tibia. Conclusion: Although structural allograft is an appropriate choice in limb reconstruction after massive resection of involved tissues in malignant and invasive bone tumors, the risk of complications such as nonunion and infection in massive allograft increases in cases of adjuvant (chemotherapy and radiotherapy modalities of treatment. Whereas the rate of tumor recurrence, metastasis, and restrictions in range of motion during a short term follow up after implantation showed no significant difference among the evaluated groups. Consequently, further attention and constant periodic visits of the patients and checking for local recurrence and distant metastasis should be done after surgery.

  17. 4D Shape-Preserving Modelling of Bone Growth

    DEFF Research Database (Denmark)

    Andresen, Per Rønsholt; Nielsen, Mads; Kreiborg, Sven

    1998-01-01

    From a set of temporally separated scannings of the same anatomical structure we wish to identify and analyze the growth in terms of a metamorphosis. That is, we study the tempral change of shape which may prowide an understanding of the biological processes which govern the growth process. We...... subdivide the growth analysis into growth simulation, growth modelling, and finally the growth analysis. In this paper, we present results of growth simulation of the mandible from 3 scannings of the same patient in the age of 9 months, 21 months, and 7 years. We also present the first growth models...... and growth analyzes. The ultimative goal is to predict/simulate human growth which would be extremely useful in many surgical procedures....

  18. Mathematical model for osteobstruction in bone regeneration mechanisms: a headway in skeletal tissue engineering.

    Science.gov (United States)

    Ogunsalu, C; Arunaye, F I; Ezeokoli, C; Gardner, M; Rohrer, M; Prasad, H

    2012-11-01

    In this paper, we formulate a mathematical model for the evaluation of parameters responsible for the retardation and eventual acceleration of bone regeneration on the contralateral side of the mandible of experimental animals, following the discovery of a new mechanism of bone regeneration called the osteobstruction mechanism (a negative mechanism of bone regeneration as opposed to the well established and extensively documented positive mechanisms such as osteogenesis, osteoinduction and osteoconduction). This osteobstructive mechanism was demonstrated by episodes of overtaking and reovertaking on single photon emission computed tomography (SPECT) following evaluation of osteoblastic activities in a sequential animal experiment to validate both the Ogunsalu sandwich technique (a double guided tissue technique; D-GTR) and the interceed membrane technique (a single guided tissue regeneration technique; S-GTR) utilizing SPECT, histological and histomorphometric evaluation. This work is now given special attention in terms of mathematical analysis because of limited experimental observations since experiments cannot be observed infinitely. Mathematical modelling is as such essential to generalize the results of this osteobstructive mechanism in bone regeneration. We utilize the Fisher's equation to describe bone cell mobilization during bone regeneration by two different techniques: the Ogunsalu sandwich bone regeneration technique (D-GTR) and the S-GTR.

  19. Disrupted bone remodeling leads to cochlear overgrowth and hearing loss in a mouse model of fibrous dysplasia.

    Directory of Open Access Journals (Sweden)

    Omar Akil

    Full Text Available Normal hearing requires exquisite cooperation between bony and sensorineural structures within the cochlea. For example, the inner ear secretes proteins such as osteoprotegrin (OPG that can prevent cochlear bone remodeling. Accordingly, diseases that affect bone regulation can also result in hearing loss. Patients with fibrous dysplasia develop trabecular bone overgrowth resulting in hearing loss if the lesions affect the temporal bones. Unfortunately, the mechanisms responsible for this hearing loss, which could be sensorineural and/or conductive, remain unclear. In this study, we used a unique transgenic mouse model of increased Gs G-protein coupled receptor (GPCR signaling induced by expression of an engineered receptor, Rs1, in osteoblastic cells. These ColI(2.3+/Rs1+ mice showed dramatic bone lesions that histologically and radiologically resembled fibrous dysplasia. We found that ColI(2.3+/Rs1+ mice showed progressive and severe conductive hearing loss. Ossicular chain impingement increased with the size and number of dysplastic lesions. While sensorineural structures were unaffected, ColI(2.3+/Rs1+ cochleae had abnormally high osteoclast activity, together with elevated tartrate resistant acid phosphatase (TRAP activity and receptor activator of nuclear factor kappa-B ligand (Rankl mRNA expression. ColI(2.3+/Rs1+ cochleae also showed decreased expression of Sclerostin (Sost, an antagonist of the Wnt signaling pathway that normally increases bone formation. The osteocyte canalicular networks of ColI(2.3+/Rs1+ cochleae were disrupted and showed abnormal osteocyte morphology. The osteocytes in the ColI(2.3+/Rs1+ cochleae showed increased expression of matrix metalloproteinase 13 (MMP-13 and TRAP, both of which can support osteocyte-mediated peri-lacunar remodeling. Thus, while the ossicular chain impingement is sufficient to account for the progressive hearing loss in fibrous dysplasia, the deregulation of bone remodeling extends to the

  20. Micro/Nano Structural Tantalum Coating for Enhanced Osteogenic Differentiation of Human Bone Marrow Stem Cells

    Directory of Open Access Journals (Sweden)

    Ding Ding

    2018-04-01

    Full Text Available Recently, tantalum has been attracting much attention for its anticorrosion resistance and biocompatibility, and it has been widely used in surface modification for implant applications. To improve its osteogenic differentiation of human bone marrow stem cells (hBMSCs, a micro/nano structure has been fabricated on the tantalum coating surface through the combination of anodic oxidation and plasma spraying method. The morphology, composition, and microstructure of the modified coating were comprehensively studied by employing scanning electron microscopy (SEM, X-ray diffraction (XRD as well as transmission electron microscopy (TEM. The effects of hierarchical structures as well as micro-porous structure of tantalum coating on the behavior for human bone marrow stem cells (hBMSCs were evaluated and compared at both cellular and molecular levels in vitro. The experimental results show that a hierarchical micro/nano structure with Ta2O5 nanotubes spread onto a micro-scale tantalum coating has been fabricated successfully, which is confirmed to promote cell adhesion and spreading. Besides, the hierarchical micro/nano tantalum coating can provide 1.5~2.1 times improvement in gene expression, compared with the micro-porous tantalum coating. It demonstrates that it can effectively enhance the proliferation and differentiation of hBMSCs in vitro.

  1. Micro/Nano Structural Tantalum Coating for Enhanced Osteogenic Differentiation of Human Bone Marrow Stem Cells.

    Science.gov (United States)

    Ding, Ding; Xie, Youtao; Li, Kai; Huang, Liping; Zheng, Xuebin

    2018-04-03

    Recently, tantalum has been attracting much attention for its anticorrosion resistance and biocompatibility, and it has been widely used in surface modification for implant applications. To improve its osteogenic differentiation of human bone marrow stem cells (hBMSCs), a micro/nano structure has been fabricated on the tantalum coating surface through the combination of anodic oxidation and plasma spraying method. The morphology, composition, and microstructure of the modified coating were comprehensively studied by employing scanning electron microscopy (SEM), X-ray diffraction (XRD) as well as transmission electron microscopy (TEM). The effects of hierarchical structures as well as micro-porous structure of tantalum coating on the behavior for human bone marrow stem cells (hBMSCs) were evaluated and compared at both cellular and molecular levels in vitro. The experimental results show that a hierarchical micro/nano structure with Ta₂O₅ nanotubes spread onto a micro-scale tantalum coating has been fabricated successfully, which is confirmed to promote cell adhesion and spreading. Besides, the hierarchical micro/nano tantalum coating can provide 1.5~2.1 times improvement in gene expression, compared with the micro-porous tantalum coating. It demonstrates that it can effectively enhance the proliferation and differentiation of hBMSCs in vitro.

  2. Transgenic medaka fish as models to analyze bone homeostasis under micro-gravity conditions in vivo

    Science.gov (United States)

    Winkler, C.; Wagner, T.; Renn, J.; Goerlich, R.; Schartl, M.

    Long-term space flight and microgravity results in bone loss that can be explained by reduced activity of bone-forming osteoblast cells and/or an increase in activity of bone resorbing osteoclast cells. Osteoprotegerin (OPG), a secreted protein of 401 amino acids, has been shown to regulate the balance between osteoblast and osteoclast formation and thereby warrants constant bone mass under normal gravitational conditions. Consistent with this, earlier reports using transgenic mice have shown that increased activation of OPG leads to exc essive bone formation (osteopetrosis), while inactivation of OPG leads to bone loss (osteoporosis). Importantly, it has recently been reported that expression of murine OPG is regulated by vector averaged gravity (Kanematsu et al., 2002, Bone 30, p553). The small bony fish medaka (Oryzias latipes ) has attracted increasing attention as genetic model system to study developmental and pathological processes. To analyze the molecular mechanisms of bone formation in this small vertebrate, we have isolated two related genes, opr-1 and opr -2, from medaka. Our phylogenetic analysis revealed that both genes originated from a common ancestor by fish-specific gene duplication and represent the orthologs of the mammalian OPG gene. Both opr genes are differentially expressed during embryonic and larval development, in adult tissues and in cultured primary osteoblast cells. We have characterized their promoter regions and identified consensus binding sites for transcription factors of the bone-morphogenetic-protein (BMP) p thway and for core-binding-factor-1Aa (cbfa1). Cbfa1 has been shown to be the key regulator of OPG expression during several steps of osteoblast differentiation in mammals. This opens the possibility that the mechanisms controlling bone formation in teleost fish and higher vertebrates are regulated by related mechanisms. We are currently generating transgenic medakafish expressing a GFP reporter gene under control of the

  3. Probiotic Lactobacillus rhamnosus GG prevents alveolar bone loss in a mouse model of experimental periodontitis.

    Science.gov (United States)

    Gatej, Simona M; Marino, Victor; Bright, Richard; Fitzsimmons, Tracy R; Gully, Neville; Zilm, Peter; Gibson, Rachel J; Edwards, Suzanne; Bartold, Peter M

    2018-02-01

    This study investigated the role of Lactobacillus rhamnosus GG (LGG) on bone loss and local and systemic inflammation in an in vivo mouse model of experimental periodontitis (PD). Experimental PD was induced in mice by oral inoculation with Porphyromonas gingivalis and Fusobacterium nucleatum over a period of 44 days. The probiotic LGG was administered via oral inoculation or oral gavage prior to, and during disease induction. The antimicrobial activity of LGG on the inoculum was also tested. Alveolar bone levels and gingival tissue changes were assessed using in vivo microcomputed tomography and histological analysis. Serum levels of mouse homologues for IL-8 were measured using multiplex assays. Pre-treatment with probiotics either via oral gavage or via oral inoculation significantly reduced bone loss (p Lactobacillus rhamnosus GG effectively suppresses bone loss in a mouse model of induced PD irrespective of the mode of administration. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  4. X-ray crystal structure of bone marrow kinase in the x chromosome: a Tec family kinase.

    Science.gov (United States)

    Muckelbauer, Jodi; Sack, John S; Ahmed, Nazia; Burke, James; Chang, Chiehying Y; Gao, Mian; Tino, Joseph; Xie, Dianlin; Tebben, Andrew J

    2011-11-01

    Bone marrow kinase in the X chromosome, a member of the Tec family of tyrosine kinases, plays a role in both monocyte/macrophage trafficking as well as cytokine secretion. Although the structures of Tec family kinases Bruton's tyrosine kinase and IL-2-inducible T-cell kinase are known, the crystal structures of other Tec family kinases have remained elusive. We report the X-ray crystal structures of bone marrow kinase in the X chromosome in complex with dasatinib at 2.4 Å resolution and PP2 at 1.9 Å resolution. The bone marrow kinase in the X chromosome structures reveal a typical kinase protein fold; with well-ordered protein conformation that includes an open/extended activation loop and a stabilized DFG-motif rendering the kinase in an inactive conformation. Dasatinib and PP2 bind to bone marrow kinase in the X chromosome in the ATP binding pocket and display similar binding modes to that observed in other Tec and Src protein kinases. The bone marrow kinase in the X chromosome structures identify conformational elements of the DFG-motif that could potentially be utilized to design potent and/or selective bone marrow kinase in the X chromosome inhibitors. © 2011 John Wiley & Sons A/S.

  5. Autoradiographic studies of the intensity of morphogenetic processes in the bone skeleton under modeling microgravity

    Science.gov (United States)

    Rodionova, N. V.; Zolotova-Haidamaka, N. V.; Nithevich, T. P.

    In ontogenesis the development of long skeleton bones and reconstruction of bone structures during adaptive remodeling are performed due to a combination of the bone apposition and bone resorption processes. With the use of radioactive markers of specific biosyntheses -3H-thymidine and 3H-glycine we studied the dynamics and peculiarities of these processes under hypokinesia by unloading the hind limbs of young white rats (tail suspension method) during 28 days. The radionuclides were administered in a single dose at the end of the experiment and the biomaterial was taken 1, 24, 48, 120 and 192 h. after injection. In histoautographs the counts were made of a nuclei labeling index (3H-thymidine), of the number of silver grains over the cells and in the forming bone matrix in growth and remodeling zones of the femoral bone (3H-glycine). The tendency for a reduction of a labeling index in the 3H-thymidine-labeled osteogenic cells in the periost and endost has been established. The dynamics of labeled cells following various intervals after 3H-thymidine injection testifies to a delay in the rates of osteoblasts' differentiation and their transformation to osteocytes in the experiment animals. 3H-glycine is assimilated by osteogenic cells 30 min after the radionuclide injection and following 24 h. it is already incorporated into the forming bone matrix. As a result an appositional bone addition by 192 h. the silver grains are registered in the bone matrix as "labeling lines". A lower 3H-glycine uptake by the osteogenic cells and bone matrix as compared with a control is indicative of a decrease of the osteoplastic process under hypokinesia, particulary in the periost. At the same time the resorption and remodeling bone zones reveal regions of an intensive 3H-glycine uptake after 1 and 24 h. We associate this latter fact with an activation of collagen proteins in the differentiating fibroblasts (instead of osteoblasts) in these locations. This is confirmed by our previous

  6. Multiscale modelling of trabecular bone: from micro to macroscale

    OpenAIRE

    Levrero Florencio, Francesc

    2017-01-01

    Trabecular bone has a complex and porous microstructure. This study develops approaches to determine the mechanical behaviour of this material at the macroscopic level through the use of homogenisation-based multiscale methods using micro-finite element simulations. In homogenisation-based finite element methods, a simulation involving a representative volume element of the microstructure of the considered material is performed with a specific set of boundary conditions. The ma...

  7. Comparison of different plasticity criteria for trabecular bone failure modelling

    Czech Academy of Sciences Publication Activity Database

    Jiroušek, Ondřej

    2008-01-01

    Roč. 8, č. 1 (2008), s. 10177-10178 ISSN 1617-7061. [Annual Meeting of International Association of Applied Mathematics and Mechanics. Bremen, 31.03.2008-04.04.2008] R&D Projects: GA ČR(CZ) GA103/05/1020 Institutional research plan: CEZ:AV0Z20710524 Keywords : nanoindentation * plasticity criteria * trabecular bone Subject RIV: FI - Traumatology, Orthopedics

  8. Generalized latent variable modeling multilevel, longitudinal, and structural equation models

    CERN Document Server

    Skrondal, Anders; Rabe-Hesketh, Sophia

    2004-01-01

    This book unifies and extends latent variable models, including multilevel or generalized linear mixed models, longitudinal or panel models, item response or factor models, latent class or finite mixture models, and structural equation models.

  9. [Application of GVF snake model in segmentation of whole body bone SPECT image].

    Science.gov (United States)

    Zhu, Chunmei; Tian, Lianfang; Chen, Ping; Wang, Lifei; Ye, Guangchun; Mao, Zongyuan

    2008-02-01

    Limited by the imaging principle of whole body bone SPECT image, the gray value of bladder area is quite high, which affects the image's brightness, contrast and readability. In the meantime, the similarity between bladder area and focus makes it difficult for some images to be segmented automatically. In this paper, an improved Snake model, GVF Snake, is adopted to automatically segment bladder area, preparing for further processing of whole body bone SPECT images.

  10. Use of Animal Models in Understanding Cancer-induced Bone Pain

    Directory of Open Access Journals (Sweden)

    Lauren M. Slosky

    2015-01-01

    Full Text Available Many common cancers have a propensity to metastasize to bone. Although malignancies often go undetected in their native tissues, bone metastases produce excruciating pain that severely compromises patient quality of life. Cancer-induced bone pain (CIBP is poorly managed with existing medications, and its multifaceted etiology remains to be fully elucidated. Novel analgesic targets arise as more is learned about this complex and distinct pain state. Over the past two decades, multiple animal models have been developed to study CIBP's unique pathology and identify therapeutic targets. Here, we review animal models of CIBP and the mechanistic insights gained as these models evolve. Findings from immunocompromised and immunocompetent host systems are discussed separately to highlight the effect of model choice on outcome. Gaining an understanding of the unique neuromolecular profile of cancer pain through the use of appropriate animal models will aid in the development of more effective therapeutics for CIBP.

  11. Time Simulation of Bone Adaptation

    DEFF Research Database (Denmark)

    Bagge, Mette

    1998-01-01

    The structural adaptation of a three-dimensional finite element model ofthe proximal femur is considered. Presuming the bone possesses the optimalstructure under the given loads, the bone material distribution is foundby minimizing the strain energy averaged over ten load cases with avolume...

  12. Kinematic models of extensional structures

    International Nuclear Information System (INIS)

    Groshong, R.H. Jr.

    1990-01-01

    This paper discusses kinematic models that can relate faults of different types and different positions within a single dynamic system and thereby offer the potential to explain the disparate seismic activity characteristic of extensional terrains. The major styles are full grabens, half grabens, domino blocks, and glide-block systems. Half grabens, the most likely models for Basin and Range structure, are formed above a master fault of decreasing dip with depth and a hangingwall that deforms as it passes over the curved fault. Second-order normal faults, typically domino style, accommodate the required hangingwall deformation. According to the author low-angle detachment faults are consistent with the evidence of seismicity only on high-angle faults if the hangingwall of the detachment is broken by multiple half-graben systems

  13. Modeling and determination of directionality of the kerf in epifluorescence sharp bone trauma analysis.

    Science.gov (United States)

    Capuani, Caroline; Telmon, Norbert; Moscovici, Jacques; Molinier, François; Aymeric, Andre; Delisle, Marie-Bernadette; Rougé, Daniel; Guilbeau-Frugier, Céline

    2014-11-01

    Characteristics of sharp bone trauma can be extremely useful to determine the origin of cut marks and to provide information regarding the context of death. Using human ribs and clavicle bones, this study analyzes the characteristics of bone kerfs made by different bladed implements, thanks to epifluorescence macroscopy. This technique, which is a nondestructive tool that uses autofluorescence of bones, documents bone damage precisely with high resolution. Both qualitative and quantitative criteria are analyzed. Our results identify unique class characteristics on bone lesions, allowing modeling kerf depending on the weapon, regardless of the type of bone that is wounded. Moreover, we demonstrate for the first time microscopic criteria of directionality, using fluorescence excitation. Orientation of cracks, flakes, and lateral pushing back especially helps in determining the tip and the end of the lesion, leading to the position of the aggressor. Kerf wall characteristics and striation location are also very useful. Epifluorescence macroscopy could be a new tool of choice in anthropology through cut mark analysis in establishing how the blade was used and providing details about the blow.

  14. Two Different Isomers of Vitamin E Prevent Bone Loss in Postmenopausal Osteoporosis Rat Model

    Directory of Open Access Journals (Sweden)

    Norliza Muhammad

    2012-01-01

    Full Text Available Postmenopausal osteoporotic bone loss occurs mainly due to cessation of ovarian function, a condition associated with increased free radicals. Vitamin E, a lipid-soluble vitamin, is a potent antioxidant which can scavenge free radicals in the body. In this study, we investigated the effects of alpha-tocopherol and pure tocotrienol on bone microarchitecture and cellular parameters in ovariectomized rats. Three-month-old female Wistar rats were randomly divided into ovariectomized control, sham-operated, and ovariectomized rats treated with either alpha-tocopherol or tocotrienol. Their femurs were taken at the end of the four-week study period for bone histomorphometric analysis. Ovariectomy causes bone loss in the control group as shown by reduction in both trabecular volume (BV/TV and trabecular number (Tb.N and an increase in trabecular separation (Tb.S. The increase in osteoclast surface (Oc.S and osteoblast surface (Ob.S in ovariectomy indicates an increase in bone turnover rate. Treatment with either alpha-tocopherol or tocotrienol prevents the reduction in BV/TV and Tb.N as well as the increase in Tb.S, while reducing the Oc.S and increasing the Ob.S. In conclusion, the two forms of vitamin E were able to prevent bone loss due to ovariectomy. Both tocotrienol and alpha-tocopherol exert similar effects in preserving bone microarchitecture in estrogen-deficient rat model.

  15. Naringin prevents bone loss in a rat model of type 1 Diabetes mellitus.

    Science.gov (United States)

    Rivoira, M; Rodríguez, V; Picotto, G; Battaglino, R; Tolosa de Talamoni, N

    2018-01-01

    The aim of this work was to know whether naringin (NA) could prevent the bone complications in a model of streptozotocin (STZ) induced diabetes. Rats were divided in: 1) controls, 2) STZ-rats, 3) STZ-rats treated with 40 mg NA/kg, and 4) STZ-rats treated with 80 mg NA/kg. BMD and BMC were performed by DEXA. Bone histomorphometry and histology as well as TRAP staining were done in tibia. Osteocalcin (OCN) was determined in bone and serum. Glutathione content and SOD and catalase activities were assayed in bone marrow from femur. The data showed that NA80 increased the BMD and BMC from the long bones of STZ-rats. Both NA40 and NA80 normalized the trabecular number and the trabecular separations. An increase in the number of adipocytes and TRAP(+) cells in tibia from STZ-rats was blocked by NA. NA40 treatment increased the number of OCN(+) cells, but only the NA80 treatment allowed to reach the control values. NA normalized the SOD and catalase activities in bone marrow of femur from STZ-rats. In conclusion, NA avoids alterations in the physical properties and microstructure of bone from STZ-rats probably by stimulation of osteoblastogenesis, inhibition of the osteoclastogenesis and adipogenesis via blocking the oxidative stress. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. Effects of Hydroxyapatite on Bone Graft Resorption in an Experimental Model of Maxillary Alveolar Arch Defects

    Directory of Open Access Journals (Sweden)

    Ozgur Pilanci

    2013-06-01

    Full Text Available Most commonly used treatments use autologous bone grafts to address bony defects in patients with cleft palate. Major disadvantages of autogenous bone grafts include donor site morbidity and resorption. Suggestions to overcome such problems include biomaterials that can be used alone or in combination with bone. We examined the effect of hydroxyapatite cement on bone graft resorption in a rabbit maxillary alveolar defect model. We divided 16 young adult albino New Zealand rabbits into two groups. A defect 1 cm wide was created in each rabbit's maxillary arch. In Group 1, the removed bone was disrupted, and the pieces were replaced in the defect. In the other group, the pieces were replaced after mixing (1:1 with hydroxyapatite cement. Quantitative computed tomographic evaluation of these grafts was performed in axial and coronal planes for each rabbit at 2 and 12 weeks. In axial images at 12 weeks, the group without cement showed mean bone resorption of 15%. In the cement group, a mean volumetric increase of 68% was seen. No resorption occurred when bone grafts were mixed with hydroxyapatite cement. [Arch Clin Exp Surg 2013; 2(3.000: 170-175

  17. Wound Models for Periodontal and Bone Regeneration: the role of biological research

    Science.gov (United States)

    Sculean, Anton; Chapple, Iain L.C.; Giannobile, William V.

    2015-01-01

    The ultimate goal of periodontal therapy remains the complete regeneration of those periodontal tissues lost to the destructive inflammatory-immune response, or to trauma, with tissues that possess the same structure and function, and to reestablish and sustain a heath promoting biofilm from one characterised by dysbiosis. This volume discusses the multiple facets of a transition during the late 1960’s to the present day, towards regenerative therapies founded upon a clearer understanding of the biophysiology of normal structure and function, rather than empiricism. This introductory manuscript provides an overview on the requirements of appropriate in-vitro laboratory models (e.g. cell culture), of pre-clinical (i.e. animal) models and human studies for periodontal wound and bone repair. Laboratory studies may provide valuable fundamental insights into basic mechanisms involved in wound repair and regeneration, but also suffer from a uni-dimensional and simplistic approach that does not account for the complexities of the in vivo situation, where multiple cell types and interactions all contribute to definitive outcomes. Therefore, such laboratory studies require validatory research employing preclinical models specifically designed to demonstrate proof-of-concept efficacy, preliminary safety and adaptation to human disease scenarios. Small animal models provide the most economic and logistically feasible preliminary approaches, but outcomes do not necessarily translate to larger animal or human models. The advantages and limitations of all periodontal regeneration models need to be carefully considered when planning investigations to ensure that the optimal design is adopted to answer the specific research question posed. Future challenges lie in the areas of stem cell research, scaffold designs, cell delivery and choice of growth factors, along with research to ensure appropriate gingival coverage in order to prevent gingival recession during the healing phase

  18. Chemical and biomechanical characterization of hyperhomocysteinemic bone disease in an animal model

    Directory of Open Access Journals (Sweden)

    Howell David S

    2003-02-01

    Full Text Available Abstract Background Classical homocystinuria is an autosomal recessive disorder caused by cystathionine β-synthase (CBS deficiency and characterized by distinctive alterations of bone growth and skeletal development. Skeletal changes include a reduction in bone density, making it a potentially attractive model for the study of idiopathic osteoporosis. Methods To investigate this aspect of hyperhomocysteinemia, we supplemented developing chicks (n = 8 with 0.6% dl-homocysteine (hCySH for the first 8 weeks of life in comparison to controls (n = 10, and studied biochemical, biomechanical and morphologic effects of this nutritional intervention. Results hCySH-fed animals grew faster and had longer tibiae at the end of the study. Plasma levels of hCySH, methionine, cystathionine, and inorganic sulfate were higher, but calcium, phosphate, and other indices of osteoblast metabolism were not different. Radiographs of the lower limbs showed generalized osteopenia and accelerated epiphyseal ossification with distinct metaphyseal and suprametaphyseal lucencies similar to those found in human homocystinurics. Although biomechanical testing of the tibiae, including maximal load to failure and bone stiffness, indicated stronger bone, strength was proportional to the increased length and cortical thickness in the hCySH-supplemented group. Bone ash weights and IR-spectroscopy of cortical bone showed no difference in mineral content, but there were higher Ca2+/PO43- and lower Ca2+/CO32- molar ratios than in controls. Mineral crystallization was unchanged. Conclusion In this chick model, hyperhomocysteinemia causes greater radial and longitudinal bone growth, despite normal indices of bone formation. Although there is also evidence for an abnormal matrix and altered bone composition, our finding of normal biomechanical bone strength, once corrected for altered morphometry, suggests that any increase in the risk of long bone fracture in human hyperhomocysteinemic

  19. The Japanese Medakafish (Oryzias latipes) as Animal Model for Space-related Bone Research

    Science.gov (United States)

    Renn, J.; Schaedel, M.; Elmasri, H.; Wagner, T.; Goerlich, R.; Furutani-Seiki, M.; Kondoh, H.; Schartl, M.; Winkler, C.

    Long-term space flight leads to bone loss due to reduced mechanical load. Animal models are needed to support the analysis of the underlying mechanisms at the molecular and cellular level that are presently largely unclear. For this, small laboratory fish offer many experimental advantages as in vivo models to study disease related processes. They produce large numbers of completely transparent embryos, are easy to keep under laboratory and space conditions and have relatively compact genomes. We are using the Japanese Medaka to characterize the genetic networks regulating bone formation and to study bone formation and remodeling under microgravity. We showed that despite the large evolutionary distance many known factors regulating bone formation are conserved between fish and humans. This includes osteoprotegerin (opg), a key regulator of bone resorption that is altered at the transcriptional level by simulated microgravity in mammals in vitro (Kanematsu et al., Bone 30, 2002). To monitor, how opg is regulated by altered gravity in vivo in fish and how fish react to microgravity, we isolated the Medaka opg regulatory region and produced transgenic fish that carry the green fluorescent protein reporter under the control of the Medaka opg promoter. This model will be useful to monitor gravity-induced changes at the molecular level in vivo. Fish also provide the opportunity to identify novel genes involved in bone formation by using large-scale mutagenesis screens. We have characterized several lines of mutant fish subjected to ENU mutagenesis that show morphological defects in the formation of the bone precursor cell compartment of the axial skeleton, the sclerotome. Using this genetic approach, the identification of the mutated genes is expected to reveal novel components of the genetic cascades that regulate bone formation. In an attempt to identify genes specifically expressed in the sclerotome in Medaka, we identified and characterized dmrt2, a gene that so far

  20. Daily Parathyroid Hormone 1-34 Replacement Therapy for Hypoparathyroidism Induces Marked Changes in Bone Turnover and Structure

    Science.gov (United States)

    Gafni, Rachel I.; Brahim, Jaime S.; Andreopoulou, Panagiota; Bhattacharyya, Nisan; Kelly, Marilyn H.; Brillante, Beth A.; Reynolds, James C.; Zhou, Hua; Dempster, David W.; Collins, Michael T.

    2012-01-01

    Parathyroid hormone (PTH) has variable actions on bone. Chronically increased PTH is catabolic leading to osteoporosis, yet intermittent administration is anabolic and increases bone mass. PTH deficiency is associated with decreased bone remodeling and increased bone mass. However, the effects of PTH replacement therapy on bone in hypoparathyroidism are not well known. We discontinued calcitriol therapy and treated five hypoparathyroid subjects (2 adults and 3 adolescents) with synthetic human PTH 1-34 (hPTH 1-34), injected 2-3 times daily for 18 months, with doses individualized to maintain serum calcium at 1.9-2.25 mmol/L. Biochemical markers and bone density (BMD) were assessed every 6 months; iliac-crest biopsies were performed before and after 1 year of treatment. hPTH 1-34 therapy significantly increased bone markers to supranormal levels. Histomorphometry revealed that treatment dramatically increased cancellous bone volume and trabecular number and decreased trabecular separation. Changes in trabecular width were variable, suggesting that the increase in trabecular number was due to the observed intratrabecular tunneling. Cortical width remained unchanged, however, hPTH 1-34 treatment increased cortical porosity. Cancellous bone remodeling was also stimulated, inducing significant changes in osteoid, mineralizing surface, and bone formation rate. Similar changes were seen in endocortical and intracortical remodeling. BMD Z-scores were unchanged at the spine and femoral neck. Total hip Z-scores increased, however, total body BMD Z-scores decreased during the first 6 months of treatment and then stabilized, remaining significantly decreased compared to baseline. Radial Z-scores also decreased with treatment; this was most pronounced in the growing adolescent. Daily hPTH 1-34 therapy for hypoparathyroidism stimulated bone turnover, increased bone volume, and altered bone structure in the iliac crest. These findings suggest that treatment with hPTH 1-34 in

  1. Alveolar bone preservation subsequent to miniscrew implant placement in a canine model.

    Science.gov (United States)

    Melsen, B; Huja, S S; Chien, H-H; Dalstra, M

    2015-05-01

    To assess the effects of transcortical screws on alveolar (bone) ridge preservation following extraction. Four adult beagle dogs had mandibular premolars extracted bilaterally. After 6 weeks, using a split-mouth design, two transcortical screws were inserted unilaterally below the alveolar crest on the experimental side in the region of the extraction. The dogs were killed after 12 weeks. The bone at the extraction sites was analyzed using μCT and 3D analysis. A cylindrical core was placed around the actual and a virtual screw placed in the identical location on the control side. The bone volume within the cylinders was quantified. An insertion of a dental implant was simulated bilaterally at the insertion site. The height of the clinical crown and the alveolar crest were determined on both sides. The bone turnover was assessed histomorphometrically on un-decalcified bucco-lingual sections stained with basic fuchsine and toluidine blue. Comparison of the two sides revealed a significant difference both with regard to the bone volume and morphology. The transcortical screw caused an increase in bone density and less ridge atrophy. When simulating a dental implant placement on both sides, the bone preservation on the experimental side led to a need for a shorter clinical crown compared to the control side. A higher activity level of the bone in the experimental side was demonstrated histologically. In this dog model the insertion of a mini-implant across the healing alveolar process results in increased density not only adjacent to the screws, but also in the region where a potential dental implant would be inserted. In humans, the insertion of transcortical screws may maintain bone when for various reasons insertion of a permanent dental implant has to be postponed. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  2. Quantification of age-related changes in the structure model type and trabecular thickness of human tibial cancellous

    DEFF Research Database (Denmark)

    Ding, Ming; Hvid, I

    2000-01-01

    Structure model type and trabecular thickness are important characteristics in describing cancellous bone architecture. It has been qualitatively observed that a radical change of trabeculae from plate-like to rod-like occurs in aging, bone remodeling, and osteoporosis. Thickness of trabeculae has......) cancellous bone. In this study, 160 human proximal tibial cancellous bone specimens from 40 normal donors, aged 16 to 85 years, were collected. These specimens were micro-computed tomography (micro-CT) scanned, then the micro-CT images were segmented using optimal thresholds. From accurate 3-D data sets...... model. Our results showed that structure model type changed towards more rod-like in the elderly, and that trabecular thickness declined significantly with age. These changes become significant after 80 years of age for human tibial cancellous bone, whereas both properties seem to remain relatively...

  3. Uncovering nanoscale electromechanical heterogeneity in the subfibrillar structure of collagen fibrils responsible for the piezoelectricity of bone.

    Science.gov (United States)

    Minary-Jolandan, Majid; Yu, Min-Feng

    2009-07-28

    Understanding piezoelectricity, the linear electromechanical transduction, in bone and tendon and its potential role in mechanoelectric transduction leading to their growth and remodeling remains a challenging subject. With high-resolution piezoresponse force microscopy, we probed piezoelectric behavior in relevant biological samples at different scale levels: from the subfibrillar structures of single isolated collagen fibrils to bone. We revealed that, beyond the general understanding of collagen fibril being a piezoelectric material, there existed an intrinsic piezoelectric heterogeneity within a collagen fibril coinciding with the periodic variation of its gap and overlap regions. This piezoelectric heterogeneity persisted even for the collagen fibrils embedded in bone, bringing about new implications for its possible roles in structural formation and remodeling of bone.

  4. Chemical structure, biosynthesis and synthesis of free and glycosylated pyridinolines formed by cross-link of bone and synovium collagen.

    Science.gov (United States)

    Anastasia, Luigi; Rota, Paola; Anastasia, Mario; Allevi, Pietro

    2013-09-21

    This review focuses on the chemical structure, biosynthesis and synthesis of free and glycosylated pyridinolines (Pyds), fluorescent collagen cross-links, with a pyridinium salt structure. Pyds derive from the degradation of bone collagen and have attracted attention for their use as biochemical markers of bone resorption and to assess fracture risk prediction in persons suffering from osteoporosis, bone cancer and other bone or collagen diseases. We consider and critically discuss all reported syntheses of free and glycosylated Pyds evidencing an unrevised chemistry, original and of general utility, analysis of which allows us to also support a previously suggested non-enzymatic formation of Pyds in collagen better rationalizing and justifying the chemical events.

  5. Instructive function of surface structure of calcium phosphate ceramics in bone regeneration

    NARCIS (Netherlands)

    Zhang, Jingwei

    2016-01-01

    The incidence of patients which require spinal fusion or bone regeneration in large bone defects caused by trauma, tumors, tumor resection, infections or abnormal skeletal development, is on the rise. Traditionally, in both spinal fusion surgery and other bone regeneration approaches, bone grafts

  6. Calcium requirements of growing rats based on bone mass, structure, or biomechanical strength are similar

    Science.gov (United States)

    Although calcium (Ca) supplementation increases bone density, the increase is small and the impact on bone strength and fracture risk is uncertain. To investigate if bone mass, morphology, and biomechanical properties are affected by deficient to copious dietary Ca concentrations, the long bones (ti...

  7. Evaluation of injectable constructs for bone repair with a subperiosteal cranial model in the rat.

    Directory of Open Access Journals (Sweden)

    Marta Kisiel

    Full Text Available While testing regenerative medicine strategies, the use of animal models that match the research questions and that are related to clinical translation is crucial. During the initial stage of evaluating new strategies for bone repair, the main goal is to state whether the strategies efficiently induce the formation of new bone tissue at an orthotopic site. Here, we present a subperiosteal model in rat calvaria that allow the evaluation of a broad range of approaches including bone augmentation, replacement and regeneration. The model is a fast to perform, minimally invasive, and has clearly defined control groups. The procedure enables to evaluate the outcomes quantitatively using micro-computed tomography and qualitatively by histology and immunohistochemistry. We established this new model, using bone morphogenetic protein-2 as an osteoinductive factor and hyaluronic acid hydrogel as injectable biomaterial. We showed that this subperiosteal cranial model offers a minimally invasive and promising solution for a rapid initial evaluation of injectables for bone repair. We believe that this approach could be a powerful platform for orthopedic research and regenerative medicine.

  8. Three-Dimensional Bone Adaptation of the Proximal Femur

    DEFF Research Database (Denmark)

    Bagge, Mette

    1998-01-01

    The bone remodeling of a three-dimensional model of the proximal femur is considered. The bone adaptation is numerically described as an evolution in time formulated such that the structural change goes in an optimal direction within each time step for the optimal boundary conditions. In the bone...... remodeling scheme is included the memory of past loadings to account for the delay in the bone response to the load changes. In order to get a realistic bone adaptation process, the bone structure at the onset of the remodeling needs to be realistic too. A start design is obtained by structural optimization...

  9. Automated morphological analysis of bone marrow cells in microscopic images for diagnosis of leukemia: nucleus-plasma separation and cell classification using a hierarchical tree model of hematopoesis

    Science.gov (United States)

    Krappe, Sebastian; Wittenberg, Thomas; Haferlach, Torsten; Münzenmayer, Christian

    2016-03-01

    The morphological differentiation of bone marrow is fundamental for the diagnosis of leukemia. Currently, the counting and classification of the different types of bone marrow cells is done manually under the use of bright field microscopy. This is a time-consuming, subjective, tedious and error-prone process. Furthermore, repeated examinations of a slide may yield intra- and inter-observer variances. For that reason a computer assisted diagnosis system for bone marrow differentiation is pursued. In this work we focus (a) on a new method for the separation of nucleus and plasma parts and (b) on a knowledge-based hierarchical tree classifier for the differentiation of bone marrow cells in 16 different classes. Classification trees are easily interpretable and understandable and provide a classification together with an explanation. Using classification trees, expert knowledge (i.e. knowledge about similar classes and cell lines in the tree model of hematopoiesis) is integrated in the structure of the tree. The proposed segmentation method is evaluated with more than 10,000 manually segmented cells. For the evaluation of the proposed hierarchical classifier more than 140,000 automatically segmented bone marrow cells are used. Future automated solutions for the morphological analysis of bone marrow smears could potentially apply such an approach for the pre-classification of bone marrow cells and thereby shortening the examination time.

  10. Finite element micro-modelling of a human ankle bone reveals the importance of the trabecular network to mechanical performance: new methods for the generation and comparison of 3D models.

    Science.gov (United States)

    Parr, W C H; Chamoli, U; Jones, A; Walsh, W R; Wroe, S

    2013-01-04

    Most modelling of whole bones does not incorporate trabecular geometry and treats bone as a solid non-porous structure. Some studies have modelled trabecular networks in isolation. One study has modelled the performance of whole human bones incorporating trabeculae, although this required considerable computer resources and purpose-written code. The difference between mechanical behaviour in models that incorporate trabecular geometry and non-porous models has not been explored. The ability to easily model trabecular networks may shed light on the mechanical consequences of bone loss in osteoporosis and remodelling after implant insertion. Here we present a Finite Element Analysis (FEA) of a human ankle bone that includes trabecular network geometry. We compare results from this model with results from non-porous models and introduce protocols achievable on desktop computers using widely available softwares. Our findings show that models including trabecular geometry are considerably stiffer than non-porous whole bone models wherein the non-cortical component has the same mass as the trabecular network, suggesting inclusion of trabecular geometry is desirable. We further present new methods for the construction and analysis of 3D models permitting: (1) construction of multi-property, non-porous models wherein cortical layer thickness can be manipulated; (2) maintenance of the same triangle network for the outer cortical bone surface in both 3D reconstruction and non-porous models allowing exact replication of load and restraint cases; and (3) creation of an internal landmark point grid allowing direct comparison between 3D FE Models (FEMs). Copyright © 2012 Elsevier Ltd. All rights reserved.

  11. Decal bone matrix as a local antibiotic delivery vehicle in a MRSA-infected bone model: An experimental study

    Directory of Open Access Journals (Sweden)

    Saraf Shyam

    2010-01-01

    Full Text Available Background: Polymethyl methacrylate (PMMA antibiotic beads though have proved their utility as a local antibiotic delivery system, however, there are limitations. Decalcified bone matrix (DBM as a vehicle of antibiotics can serve the purpose, provided a minimum inhibitory concentration is sustained. Healing of the defect and avoiding the second surgery is another advantage. We studied the DBM as the delivery vehicle for vancomycin in controlling the methicillin-resistant Staphylococcus aureus (MRSA osteomyelitis as well as healing of the cavity simultaneously in an experimental study. Materials and Methods: An in vitro study was conducted to optimize vancomycin impregnation in the DBM. For the in vivo study, a unicortical defect was created in the metaphysis of the distal femur in 18 rabbits. After contaminating the defect with MRSA, rabbits were divided into three groups. Group I (eight limbs received no graft. Defects in group II (11 limbs were filled with plain DBM chips and in group III (14 limbs, cavities were implanted with vancomycin-impregnated decal bone chips. Rabbits were assessed by clinical, radiological, histological, gross examination and bacterial load assay. High Performance Liquid Chromatography HPLC analysis of vancomycin in group III was done to assess the concentration in DBM chips. Results: In group I, the infection persisted throughout the period of the study. Group II showed the fulminated infection at the grafted site with DBM chips sequestrating out. Vancomycin-impregnated decal chips in group III did not show any sign of infection and eventually incorporated. The bacterial load study showed a progressive load change and HPLC revealed an effective antibiotic concentration up to 3 weeks in both in vitro and in vivo. Conclusion: Decal bone chips were effective as the local antibiotic delivery vehicle in preventing the MRSA osteomyelitis model. It eluted vancomycin significantly and the graft uptake was also excellent

  12. In Vitro Corrosion Assessment of Additively Manufactured Porous NiTi Structures for Bone Fixation Applications

    Directory of Open Access Journals (Sweden)

    Hamdy Ibrahim

    2018-03-01

    Full Text Available NiTi alloys possess distinct functional properties (i.e., shape memory effect and superelasticity and biocompatibility, making them appealing for bone fixation applications. Additive manufacturing offers an alternative method for fabricating NiTi parts, which are known to be very difficult to machine using conventional manufacturing methods. However, poor surface quality, and the presence of impurities and defects, are some of the major concerns associated with NiTi structures manufactured using additive manufacturing. The aim of this study is to assess the in vitro corrosion properties of additively manufactured NiTi structures. NiTi samples (bulk and porous were produced using selective laser melting (SLM, and their electrochemical corrosion characteristics and Ni ion release levels were measured and compared with conventionally fabricated NiTi parts. The additively manufactured NiTi structures were found to have electrochemical corrosion characteristics similar to those found for the conventionally fabricated NiTi alloy samples. The highest Ni ion release level was found in the case of 50% porous structures, which can be attributed to their significantly higher exposed surface area. However, the Ni ion release levels reported in this work for all the fabricated structures remain within the range of most of values for conventionally fabricated NiTi alloys reported in the literature. The results of this study suggest that the proposed SLM fabrication process does not result in a significant deterioration in the corrosion resistance of NiTi parts, making them suitable for bone fixation applications.

  13. Subchondral bone response to injected adipose-derived stromal cells for treating osteoarthritis using an experimental rabbit model.

    Science.gov (United States)

    Parrilli, A; Giavaresi, G; Ferrari, A; Salamanna, F; Desando, G; Grigolo, B; Martini, L; Fini, M

    2017-01-01

    Although articular cartilage is the target of osteoarthritis (OA), its deterioration is not always clearly associated with patient symptoms. Because a functional interaction between cartilage and bone is crucial, the pathophysiology of OA and its treatment strategy must focus also on subchondral bone. We investigated whether adipose-derived stromal cells (ASCs) injected into a joint at two different concentrations could prevent subchondral bone damage after the onset of mild OA in a rabbit model. We measured both volumetric and densitometric aspects of bone remodeling. Although OA can stimulate bone remodeling either catabolically or anabolically over time, the accelerated turnover does not allow complete mineralization of new bone and therefore gradually reduces its density. We measured changes in morphometric and densitometric bone parameters using micro-CT analysis and correlated them with the corresponding parameters in cartilage and meniscus. We found that ASCs promoted cartilage repair and helped counteract the accelerated bone turnover that occurs with OA.

  14. Human breast cancer bone metastasis in vitro and in vivo: a novel 3D model system for studies of tumour cell-bone cell interactions.

    Science.gov (United States)

    Holen, I; Nutter, F; Wilkinson, J M; Evans, C A; Avgoustou, P; Ottewell, Penelope D

    2015-10-01

    Bone is established as the preferred site of breast cancer metastasis. However, the precise mechanisms responsible for this preference remain unidentified. In order to improve outcome for patients with advanced breast cancer and skeletal involvement, we need to better understand how this process is initiated and regulated. As bone metastasis cannot be easily studied in patients, researchers have to date mainly relied on in vivo xenograft models. A major limitation of these is that they do not contain a human bone microenvironment, increasingly considered to be an important component of metastases. In order to address this shortcoming, we have developed a novel humanised bone model, where 1 × 10(5) luciferase-expressing MDA-MB-231 or T47D human breast tumour cells are seeded on viable human subchaodral bone discs in vitro. These discs contain functional osteoclasts 2-weeks after in vitro culture and positive staining for calcine 1-week after culture demonstrating active bone resorption/formation. In vitro inoculation of MDA-MB-231 or T47D cells colonised human bone cores and remained viable for <4 weeks, however, use of matrigel to enhance adhesion or a moving platform to increase diffusion of nutrients provided no additional advantage. Following colonisation by the tumour cells, bone discs pre-seeded with MDA-MB-231 cells were implanted subcutaneously into NOD SCID mice, and tumour growth monitored using in vivo imaging for up to 6 weeks. Tumour growth progressed in human bone discs in 80 % of the animals mimicking the later stages of human bone metastasis. Immunohistochemical and PCR analysis revealed that growing MDA-MB-231 cells in human bone resulted in these cells acquiring a molecular phenotype previously associated with breast cancer bone metastases. MDA-MB-231 cells grown in human bone discs showed increased expression of IL-1B, HRAS and MMP9 and decreased expression of S100A4, whereas, DKK2 and FN1 were unaltered compared with the same cells grown in

  15. Finite element analysis of osteosynthesis screw fixation in the bone stock: an appropriate method for automatic screw modelling.

    Directory of Open Access Journals (Sweden)

    Jan Wieding

    Full Text Available The use of finite element analysis (FEA has grown to a more and more important method in the field of biomedical engineering and biomechanics. Although increased computational performance allows new ways to generate more complex biomechanical models, in the area of orthopaedic surgery, solid modelling of screws and drill holes represent a limitation of their use for individual cases and an increase of computational costs. To cope with these requirements, different methods for numerical screw modelling have therefore been investigated to improve its application diversity. Exemplarily, fixation was performed for stabilization of a large segmental femoral bone defect by an osteosynthesis plate. Three different numerical modelling techniques for implant fixation were used in this study, i.e. without screw modelling, screws as solid elements as well as screws as structural elements. The latter one offers the possibility to implement automatically generated screws with variable geometry on arbitrary FE models. Structural screws were parametrically generated by a Python script for the automatic generation in the FE-software Abaqus/CAE on both a tetrahedral and a hexahedral meshed femur. Accuracy of the FE models was confirmed by experimental testing using a composite femur with a segmental defect and an identical osteosynthesis plate for primary stabilisation with titanium screws. Both deflection of the femoral head and the gap alteration were measured with an optical measuring system with an accuracy of approximately 3 µm. For both screw modelling techniques a sufficient correlation of approximately 95% between numerical and experimental analysis was found. Furthermore, using structural elements for screw modelling the computational time could be reduced by 85% using hexahedral elements instead of tetrahedral elements for femur meshing. The automatically generated screw modelling offers a realistic simulation of the osteosynthesis fixation with

  16. Finite element analysis of osteosynthesis screw fixation in the bone stock: an appropriate method for automatic screw modelling.

    Science.gov (United States)

    Wieding, Jan; Souffrant, Robert; Fritsche, Andreas; Mittelmeier, Wolfram; Bader, Rainer

    2012-01-01

    The use of finite element analysis (FEA) has grown to a more and more important method in the field of biomedical engineering and biomechanics. Although increased computational performance allows new ways to generate more complex biomechanical models, in the area of orthopaedic surgery, solid modelling of screws and drill holes represent a limitation of their use for individual cases and an increase of computational costs. To cope with these requirements, different methods for numerical screw modelling have therefore been investigated to improve its application diversity. Exemplarily, fixation was performed for stabilization of a large segmental femoral bone defect by an osteosynthesis plate. Three different numerical modelling techniques for implant fixation were used in this study, i.e. without screw modelling, screws as solid elements as well as screws as structural elements. The latter one offers the possibility to implement automatically generated screws with variable geometry on arbitrary FE models. Structural screws were parametrically generated by a Python script for the automatic generation in the FE-software Abaqus/CAE on both a tetrahedral and a hexahedral meshed femur. Accuracy of the FE models was confirmed by experimental testing using a composite femur with a segmental defect and an identical osteosynthesis plate for primary stabilisation with titanium screws. Both deflection of the femoral head and the gap alteration were measured with an optical measuring system with an accuracy of approximately 3 µm. For both screw modelling techniques a sufficient correlation of approximately 95% between numerical and experimental analysis was found. Furthermore, using structural elements for screw modelling the computational time could be reduced by 85% using hexahedral elements instead of tetrahedral elements for femur meshing. The automatically generated screw modelling offers a realistic simulation of the osteosynthesis fixation with screws in the adjacent

  17. Soil Retaining Structures : Development of models for structural analysis

    NARCIS (Netherlands)

    Bakker, K.J.

    2000-01-01

    The topic of this thesis is the development of models for the structural analysis of soil retaining structures. The soil retaining structures being looked at are; block revetments, flexible retaining walls and bored tunnels in soft soil. Within this context typical structural behavior of these

  18. Instrumental methods and techniques for structural and physicochemical characterization of biomaterials and bone tissue: A review.

    Science.gov (United States)

    Mitić, Žarko; Stolić, Aleksandra; Stojanović, Sanja; Najman, Stevo; Ignjatović, Nenad; Nikolić, Goran; Trajanović, Miroslav

    2017-10-01

    A review of recent advances in instrumental methods and techniques for structural and physicochemical characterization of biomaterials and bone tissue is presented in this paper. In recent years, biomaterials attracted great attention primarily because of the wide range of biomedical applications. This paper focuses on the practical aspects of instrumental methods and techniques that were most often applied (X-ray methods, vibrational spectroscopy (IR and Raman), magnetic-resonance spectroscopy (NMR and ESR), mass spectrometry (MS), atomic absorption spectrometry (AAS) and inductively coupled plasma-atomic emission spectrometry (ICP-AES), thermogravimetry (TG), differential thermal analysis (DTA) and differential scanning calorimetry (DSC), scanning electron microscopy (SEM), transmission electron microscopy (TEM)) in the structural investigation and physicochemical characterization of biomaterials and bone tissue. The application of some other physicochemical methods was also discussed. Hands-on information is provided about these valuable research tools, emphasizing practical aspects such as typical measurement conditions, their limitations and advantages, interpretation of results and practical applications. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. A mechano-biological model of multi-tissue evolution in bone

    Science.gov (United States)

    Frame, Jamie; Rohan, Pierre-Yves; Corté, Laurent; Allena, Rachele

    2017-12-01

    Successfully simulating tissue evolution in bone is of significant importance in predicting various biological processes such as bone remodeling, fracture healing and osseointegration of implants. Each of these processes involves in different ways the permanent or transient formation of different tissue types, namely bone, cartilage and fibrous tissues. The tissue evolution in specific circumstances such as bone remodeling and fracturing healing is currently able to be modeled. Nevertheless, it remains challenging to predict which tissue types and organization can develop without any a priori assumptions. In particular, the role of mechano-biological coupling in this selective tissue evolution has not been clearly elucidated. In this work, a multi-tissue model has been created which simultaneously describes the evolution of bone, cartilage and fibrous tissues. The coupling of the biological and mechanical factors involved in tissue formation has been modeled by defining two different tissue states: an immature state corresponding to the early stages of tissue growth and representing cell clusters in a weakly neo-formed Extra Cellular Matrix (ECM), and a mature state corresponding to well-formed connective tissues. This has allowed for the cellular processes of migration, proliferation and apoptosis to be described simultaneously with the changing ECM properties through strain driven diffusion, growth, maturation and resorption terms. A series of finite element simulations were carried out on idealized cantilever bending geometries. Starting from a tissue composition replicating a mid-diaphysis section of a long bone, a steady-state tissue formation was reached over a statically loaded period of 10,000 h (60 weeks). The results demonstrated that bone formation occurred in regions which are optimally physiologically strained. In two additional 1000 h bending simulations both cartilaginous and fibrous tissues were shown to form under specific geometrical and loading

  20. Structural and mechanical differences between collagen homo- and heterotrimers: relevance for the molecular origin of brittle bone disease.

    Science.gov (United States)

    Chang, Shu-Wei; Shefelbine, Sandra J; Buehler, Markus J

    2012-02-08

    Collagen constitutes one-third of the human proteome, providing mechanical stability, elasticity, and strength to organisms. Normal type I collagen is a heterotrimer triple-helical molecule consisting of two α-1 chains and one α-2 chain. The homotrimeric isoform of type I collagen, which consists of three α-1 chains, is only found in fetal tissues, fibrosis, and cancer in humans. A mouse model of the genetic brittle bone disease, osteogenesis imperfect, oim, is characterized by a replacement of the α-2 chain by an α-1 chain, resulting also in a homotrimer collagen molecule. Experimental studies of oim mice tendon and bone have shown reduced mechanical strength compared to normal mice. The relationship between the molecular content and the decrease in strength is, however, still unknown. Here, fully atomistic simulations of a section of mouse type I heterotrimer and homotrimer collagen molecules are developed to explore the effect of the substitution of the α-2 chain. We calculate the persistence length and carry out a detailed analysis of the structure to determine differences in structural and mechanical behavior between hetero- and homotrimers. The results show that homotrimer persistence length is half of that of the heterotrimer (96 Å vs. 215 Å), indicating it is more flexible and confirmed by direct mechanical testing. Our structural analyses reveal that in contrast to the heterotrimer, the homotrimer easily forms kinks and freely rotates with angles much larger than heterotrimer. These local kinks may explain the larger lateral distance between collagen molecules seen in the fibrils of oim mice tendon and could have implications for reducing the intermolecular cross-linking, which is known to reduce the mechanical strength. Copyright © 2012 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  1. Remnant Woven Bone and Calcified Cartilage in Mouse Bone: Differences between Ages/Sex and Effects on Bone Strength.

    Directory of Open Access Journals (Sweden)

    Victoria Ip

    Full Text Available Mouse models are used frequently to study effects of bone diseases and genetic determinates of bone strength. Murine bones have an intracortical band of woven bone that is not present in human bones. This band is not obvious under brightfield imaging and not typically analyzed. Due to the band's morphology and location it has been theorized to be remnant bone from early in life. Furthermore, lamellar and woven bone are well known to have differing mechanical strengths. The purpose of this study was to determine (i if the band is from early life and (ii if the woven bone or calcified cartilage contained within the band affect whole bone strength.In twelve to fourteen week old mice, doxycycline was used to label bone formed prior to 3 weeks old. Doxycycline labeling and woven bone patterns on contralateral femora matched well and encompassed an almost identical cross-sectional area. Also, we highlight for the first time in mice the presence of calcified cartilage exclusively within the band. However, calcified cartilage could not be identified on high resolution cone-beam microCT scans when examined visually or by thresholding methods.Subsequently, three-point bending was used to analyze the effects of woven bone and calcified cartilage on whole bone mechanics in a cohort of male and female six and 13 week old Balb/C mice. Three-point bending outcomes were correlated with structural and compositional measures using multivariate linear regression. Woven bone composed a higher percent of young bones than older bones. However, calcified cartilage in older bones was twice that of younger bones, which was similar when normalized by area. Area and/or tissue mineral density accounted for >75% of variation for most strength outcomes. Percent calcified cartilage added significant predictive power to maximal force and bending stress. Calcified cartilage and woven bone could have more influence in genetic models where calcified cartilage percent is double

  2. Methodologies for Development of Patient Specific Bone Models from Human Body CT Scans

    Science.gov (United States)

    Chougule, Vikas Narayan; Mulay, Arati Vinayak; Ahuja, Bharatkumar Bhagatraj

    2016-06-01

    This work deals with development of algorithm for physical replication of patient specific human bone and construction of corresponding implants/inserts RP models by using Reverse Engineering approach from non-invasive medical images for surgical purpose. In medical field, the volumetric data i.e. voxel and triangular facet based models are primarily used for bio-modelling and visualization, which requires huge memory space. On the other side, recent advances in Computer Aided Design (CAD) technology provides additional facilities/functions for design, prototyping and manufacturing of any object having freeform surfaces based on boundary representation techniques. This work presents a process to physical replication of 3D rapid prototyping (RP) physical models of human bone from various CAD modeling techniques developed by using 3D point cloud data which is obtained from non-invasive CT/MRI scans in DICOM 3.0 format. This point cloud data is used for construction of 3D CAD model by fitting B-spline curves through these points and then fitting surface between these curve networks by using swept blend techniques. This process also can be achieved by generating the triangular mesh directly from 3D point cloud data without developing any surface model using any commercial CAD software. The generated STL file from 3D point cloud data is used as a basic input for RP process. The Delaunay tetrahedralization approach is used to process the 3D point cloud data to obtain STL file. CT scan data of Metacarpus (human bone) is used as the case study for the generation of the 3D RP model. A 3D physical model of the human bone is generated on rapid prototyping machine and its virtual reality model is presented for visualization. The generated CAD model by different techniques is compared for the accuracy and reliability. The results of this research work are assessed for clinical reliability in replication of human bone in medical field.

  3. Mandibular bone structure, bone mineral density, and clinical variables as fracture predictors: a 15-year follow-up of female patients in a dental clinic.

    Science.gov (United States)

    Jonasson, Grethe; Billhult, Annika

    2013-09-01

    To compare three mandibular trabeculation evaluation methods, clinical variables, and osteoporosis as fracture predictors in women. One hundred and thirty-six female dental patients (35-94 years) answered a questionnaire in 1996 and 2011. Using intra-oral radiographs from 1996, five methods were compared as fracture predictors: (1) mandibular bone structure evaluated with a visual radiographic index, (2) bone texture, (3) size and number of intertrabecular spaces calculated with Jaw-X software, (4) fracture probability calculated with a fracture risk assessment tool (FRAX), and (5) osteoporosis diagnosis based on dual-energy-X-ray absorptiometry. Differences were assessed with the Mann-Whitney test and relative risk calculated. Previous fracture, gluco-corticoid medication, and bone texture were significant indicators of future and total (previous plus future) fracture. Osteoporosis diagnosis, sparse trabeculation, Jaw-X, and FRAX were significant predictors of total but not future fracture. Clinical and oral bone variables may identify individuals at greatest risk of fracture. Copyright © 2013 Elsevier Inc. All rights reserved.

  4. Thyroid hormone interacts with the sympathetic nervous system to modulate bone mass and structure in young adult mice.

    Science.gov (United States)

    Fonseca, Tatiana L; Teixeira, Marilia B C G; Miranda-Rodrigues, Manuela; Rodrigues-Miranda, Manuela; Silva, Marcos V; Martins, Gisele M; Costa, Cristiane C; Arita, Danielle Y; Perez, Juliana D; Casarini, Dulce E; Brum, Patricia C; Gouveia, Cecilia H A

    2014-08-15

    To investigate whether thyroid hormone (TH) interacts with the sympathetic nervous system (SNS) to modulate bone mass and structure, we studied the effects of daily T3 treatment in a supraphysiological dose for 12 wk on the bone of young adult mice with chronic sympathetic hyperactivity owing to double-gene disruption of adrenoceptors that negatively regulate norepinephrine release, α(2A)-AR, and α(2C)-AR (α(2A/2C)-AR(-/-) mice). As expected, T3 treatment caused a generalized decrease in the areal bone mineral density (aBMD) of WT mice (determined by DEXA), followed by deleterious effects on the trabecular and cortical bone microstructural parameters (determined by μCT) of the femur and vertebra and on the biomechanical properties (maximum load, ultimate load, and stiffness) of the femur. Surprisingly, α(2A/2C)-AR(-/-) mice were resistant to most of these T3-induced negative effects. Interestingly, the mRNA expression of osteoprotegerin, a protein that limits osteoclast activity, was upregulated and downregulated by T3 in the bone of α(2A/2C)-AR(-/-) and WT mice, respectively. β1-AR mRNA expression and IGF-I serum levels, which exert bone anabolic effects, were increased by T3 treatment only in α(2A/2C)-AR(-/-) mice. As expected, T3 inhibited the cell growth of calvaria-derived osteoblasts isolated from WT mice, but this effect was abolished or reverted in cells isolated from KO mice. Collectively, these findings support the hypothesis of a TH-SNS interaction to control bone mass and structure of young adult mice and suggests that this interaction may involve α2-AR signaling. Finally, the present findings offer new insights into the mechanisms through which TH regulates bone mass, structure, and physiology. Copyright © 2014 the American Physiological Society.

  5. Crude Fucoidan Extracts Impair Angiogenesis in Models Relevant for Bone Regeneration and Osteosarcoma via Reduction of VEGF and SDF-1

    Directory of Open Access Journals (Sweden)

    Fanlu Wang

    2017-06-01

    Full Text Available The marine origin polysaccharide fucoidan combines multiple biological activities. As demonstrated by various studies in vitro and in vivo, fucoidans show anti-viral, anti-tumor, anti-oxidant, anti-inflammatory and anti-coagulant properties, although the detailed molecular action remains to be elucidated. The aim of the present study is to assess the impact of crude fucoidan extracts, on the formation of vascular structures in co-culture models relevant for bone vascularization during bone repair and for vascularization processes in osteosarcoma. The co-cultures consisted of bone marrow derived mesenchymal stem cells, respectively the osteosarcoma cell line MG63, and human blood derived outgrowth endothelial cells (OEC. The concentration dependent effects on the metabolic activity on endothelial cells and osteoblast cells were first assessed using monocultures of OEC, MSC and MG63 suggesting a concentration of 100 µg/mL as a suitable concentration for further experiments. In co-cultures fucoidan significantly reduced angiogenesis in MSC/OEC but also in MG63/OEC co-cultures suggesting a potential application of fucoidan to lower the vascularization in bone tumors such as osteosarcoma. This was associated with a decrease in VEGF (vascular endothelial growth factor and SDF-1 (stromal derived factor-1 on the protein level, both related to the control of angiogenesis and furthermore discussed as crucial factors in osteosarcoma progression and metastasis. In terms of bone formation, fucoidan slightly lowered on the calcification process in MSC monocultures and MSC/OEC co-cultures. In summary, these data suggest the suitability of lower fucoidan doses to limit angiogenesis for instance in osteosarcoma.

  6. Spinal high-mobility group box 1 contributes to mechanical allodynia in a rat model of bone cancer pain

    International Nuclear Information System (INIS)

    Tong, Wei; Wang, Wei; Huang, Jing; Ren, Ning; Wu, Sheng-Xi; Li, Yong-Qi

    2010-01-01

    Mechanisms underlying bone cancer-induced pain are largely unknown. Previous studies indicate that neuroinflammation in the spinal dorsal horn is especially involved. Being first reported as a nonhistone chromosomal protein, high-mobility group box 1 (HMGB1) is now implicated as a mediator of inflammation. We hypothesized that HMGB1 could trigger the release of cytokines in the spinal dorsal horn and contribute to bone cancer pain. To test this hypothesis, we first built a bone cancer pain model induced by intratibal injection of Walker 256 mammary gland carcinoma cells. The structural damage to the tibia was monitored by radiological analysis. The mechanical allodynia was measured and the expression of spinal HMGB1 and IL-1β was evaluated. We observed that inoculation of cancer cells, but not heat-killed cells, induced progressive bone destruction from 9 d to 21 d post inoculation. Behavioral tests demonstrated that the significant nociceptive response in the cancer cells-injected rats emerged on day 9 and this kind of mechanical allodynia lasted at least 21 d following inoculation. Tumor cells inoculation significantly increased HMGB1 expression in the spinal dorsal horn, while intrathecal injecting a neutralizing antibody against HMGB1 showed an effective and reliable anti-allodynia effect with a dose-dependent manner. IL-1β was significantly increased in caner pain rats while intrathecally administration of anti-HMGB1 could decrease IL-1β. Together with previous reports, we predict that bone cancer induces HMGB1 production, enhancing spinal IL-1β expression and thus modulating spinal excitatory synaptic transmission and pain response.

  7. Myricetin Prevents Alveolar Bone Loss in an Experimental Ovariectomized Mouse Model of Periodontitis

    Directory of Open Access Journals (Sweden)

    Jialiang Huang

    2016-03-01

    Full Text Available Periodontitis is a common chronic inflammatory disease, which leads to alveolar bone resorption. Healthy and functional alveolar bone, which can support the teeth and enable their movement, is very important for orthodontic treatment. Myricetin inhibited osteoclastogenesis by suppressing the expression of some genes, signaling pathways, and cytokines. This study aimed to investigate the effects of myricetin on alveolar bone loss in an ovariectomized (OVX mouse model of periodontitis as well as in vitro osteoclast formation and bone resorption. Twenty-four healthy eight-week-old C57BL/J6 female mice were assigned randomly to four groups: phosphate-buffered saline (PBS control (sham OVX + ligature + PBS (vehicle, and OVX + ligature + low or high (2 or 5 mg∙kg−1∙day−1, respectively doses of myricetin. Myricetin or PBS was injected intraperitoneally (i.p. every other day for 30 days. The maxillae were collected and subjected to further examination, including micro-computed tomography (micro-CT, hematoxylin and eosin (H&E staining, and tartrate-resistant acid phosphatase (TRAP staining; a resorption pit assay was also performed in vitro to evaluate the effects of myricetin on receptor activator of nuclear factor κ-B ligand (RANKL-induced osteoclastogenesis. Myricetin, at both high and low doses, prevented alveolar bone resorption and increased alveolar crest height in the mouse model and inhibited osteoclast formation and bone resorption in vitro. However, myricetin was more effective at high dose than at low dose. Our study demonstrated that myricetin had a positive effect on alveolar bone resorption in an OVX mouse model of periodontitis and, therefore, may be a potential agent for the treatment of periodontitis and osteoporosis.

  8. Biomechanical Comparison of Cadaveric and Commercially Available Synthetic Osteoporotic Bone Analogues in a Locked Plate Fracture Model Under Torsional Loading.

    Science.gov (United States)

    Becker, Edward H; Kim, Hyunchul; Shorofsky, Michael; Hsieh, Adam H; Watson, Jeffrey D; OʼToole, Robert V

    2017-05-01

    Biomechanical studies of osteoporotic bone have used synthetic models rather than cadaveric samples because of decreased variability, increased availability, and overall ease of the use of synthetic models. We compared the torsional mechanical properties of cadaveric osteoporotic bone with those of currently available synthetic osteoporotic bone analogues. We tested 12 osteoporotic cadaveric humeri and 6 specimens each of 6 types of synthetic analogues. A 5-mm fracture gap model and posterior plating technique with 4.5-mm narrow 10-hole locking compression plate were used. Torque was applied to a peak of ±10 N·m for 1000 cycles at 0.3 Hz. Data were continuously collected during cyclical and ramped loading with a servohydraulic materials testing system. Cadaveric bone had a 17% failure rate before completing 1000 cycles. Three osteoporotic bone models had 100% failure (P Osteoporotic bone analogues had torsional mechanical properties different from those of osteoporotic cadaveric specimens. The differences between osteoporotic cadaveric humeri and synthetic osteoporotic bone analogues ranged from profound with complete catastrophic failure after a few cycles to subtler differences in stiffness and strain hardening. These findings suggest that different bone analogue models vary substantially in their torsional mechanical properties and might not be appropriate substitutes for cadaveric bone in biomechanical studies of osteoporotic bone.

  9. Models and structures: mathematical physics

    International Nuclear Information System (INIS)

    2003-01-01

    This document gathers research activities along 5 main directions. 1) Quantum chaos and dynamical systems. Recent results concern the extension of the exact WKB method that has led to a host of new results on the spectrum and wave functions. Progress have also been made in the description of the wave functions of chaotic quantum systems. Renormalization has been applied to the analysis of dynamical systems. 2) Combinatorial statistical physics. We see the emergence of new techniques applied to various such combinatorial problems, from random walks to random lattices. 3) Integrability: from structures to applications. Techniques of conformal field theory and integrable model systems have been developed. Progress is still made in particular for open systems with boundary conditions, in connection to strings and branes physics. Noticeable links between integrability and exact WKB quantization to 2-dimensional disordered systems have been highlighted. New correlations of eigenvalues and better connections to integrability have been formulated for random matrices. 4) Gravities and string theories. We have developed aspects of 2-dimensional string theory with a particular emphasis on its connection to matrix models as well as non-perturbative properties of M-theory. We have also followed an alternative path known as loop quantum gravity. 5) Quantum field theory. The results obtained lately concern its foundations, in flat or curved spaces, but also applications to second-order phase transitions in statistical systems

  10. Models and structures: mathematical physics

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2003-07-01

    This document gathers research activities along 5 main directions. 1) Quantum chaos and dynamical systems. Recent results concern the extension of the exact WKB method that has led to a host of new results on the spectrum and wave functions. Progress have also been made in the description of the wave functions of chaotic quantum systems. Renormalization has been applied to the analysis of dynamical systems. 2) Combinatorial statistical physics. We see the emergence of new techniques applied to various such combinatorial problems, from random walks to random lattices. 3) Integrability: from structures to applications. Techniques of conformal field theory and integrable model systems have been developed. Progress is still made in particular for open systems with boundary conditions, in connection to strings and branes physics. Noticeable links between integrability and exact WKB quantization to 2-dimensional disordered systems have been highlighted. New correlations of eigenvalues and better connections to integrability have been formulated for random matrices. 4) Gravities and string theories. We have developed aspects of 2-dimensional string theory with a particular emphasis on its connection to matrix models as well as non-perturbative properties of M-theory. We have also followed an alternative path known as loop quantum gravity. 5) Quantum field theory. The results obtained lately concern its foundations, in flat or curved spaces, but also applications to second-order phase transitions in statistical systems.

  11. Comparative analysis of trabecular bone structure and orientation in South African hominin tali.

    Science.gov (United States)

    Su, Anne; Carlson, Kristian J

    2017-05-01

    Tali of several hominin taxa are preserved in the fossil record and studies of the external morphology of these often show a mosaic of human-like and ape-like features. This has contributed to a growing recognition of variability characterizing locomotor kinematics of Australopithecus. In contrast, locomotor kinematics of another Plio-Pleistocene hominin, Paranthropus, are substantially less well-documented, in part, because of the paucity of postcranial fossils securely attributed to the genus. Since the talus transmits locomotor-based loads through the ankle and its internal structure is hypothesized to reflect accommodation to such loads, it is a cornerstone structure for reconstructing locomotor kinematics. Here we quantify and characterize trabecular bone morphology within tali attributed to Australopithecus africanus (StW 102, StW 363, StW 486) and Paranthropus robustus (TM 1517), making quantitative comparisons to modern humans, extant non-human apes, baboons, and a hominin talus attributed to Paranthropus boisei (KNM-ER 1464). Using high-resolution images of fossil tali (25 μm voxels), nine trabecular bone subregions of interest beneath the articular surface of the talar trochlea were segmented to quantify localized patterns in distribution and primary strut orientation. It was found that trabecular strut orientation and shape, in some cases, can discriminate amongst species characterized by different locomotor foot kinematics. Discriminant function analyses using standard trabecular bone structural properties align TM 1517 with Pan and Gorilla, while other hominin tali structurally most resemble those of baboons. In primary strut orientation, Paranthropus tali (KNM-ER 1464 and TM 1517) resemble the human condition in the anterior-medial subregion, where strut orientation appears positioned to distribute compressive loads medially and distally toward the talar head. In A. africanus tali (particularly StW 486), primary strut orientation in this region

  12. The incorporation of fluoride and strontium in hydroxyapatite affects the composition, structure, and mechanical properties of human cortical bone.

    Science.gov (United States)

    Riedel, Christoph; Zimmermann, Elizabeth A; Zustin, Jozef; Niecke, Manfred; Amling, Michael; Grynpas, Marc; Busse, Björn

    2017-02-01

    Strontium ranelate and fluoride salts are therapeutic options to reduce fracture risk in osteoporosis. Incorporation of these elements in the physiological hydroxyapatite matrix of bone is accompanied by changes in bone remodeling, composition, and structure. However, a direct comparison of the effectiveness of strontium and fluoride treatment in human cortical bone with a focus on the resulting mechanical properties remains to be established. Study groups are composed of undecalcified specimens from healthy controls, treatment-naïve osteoporosis cases, and strontium ranelate or fluoride-treated osteoporosis cases. Concentrations of both elements were determined using instrumental neutron activation analysis (INAA). Backscattered electron imaging was carried out to investigate the calcium content and the cortical microstructure. In comparison to osteoporotic patients, fluoride and strontium-treated patients have a lower cortical porosity indicating an improvement in bone microstructure. Mechanical properties were assessed via reference point indentation as a measure of bone's resistance to deformation. The strontium-incorporation led to significantly lower total indentation distance values compared to osteoporotic cases; controls have the highest resistance to indentation. In conclusion, osteoporosis treatment with strontium and fluoride showed positive effects on the microstructure and the mechanical characteristics of bone in comparison to treatment-naïve osteoporotic bone. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 433-442, 2017. © 2016 Wiley Periodicals, Inc.

  13. Experimental model of a bone gap by radial ostectomy in rabbits

    Directory of Open Access Journals (Sweden)

    Antonio Carlos Cunha Lacreta Junior

    2010-09-01

    Full Text Available A lot of experimental models have been used to study the process of a fracture’s consolidation, but the problem is that due to anatomic, biologic and technical differences, these models do not always have appropriate parameters for the exact species, for which the experiment was done. The rabbit is an experimental model that is widely used in studies involving bone physiopatology in the face of fractures and their different types of treatment, corresponding to approximately 35% of all the musculoskeletic system’s scientific studies. Several surgical techniques have been used on rabbit’s bone for experimental studies, and the partial ostectomy of the radius bone is one of them. In this study, 14 rabbits (Oryctolagus cuniculus familiaris, males, adults, of white New Zeland breed, neutered, with weight between three and four kilograms, were used. Clinically, the animals did not present any alterations that compromised the study. There were evaluated through radiographic exam on days zero, 30 and 60 after the surgery, visualizing the quality of the gap and the relevant alteration of bone proliferation. The histologic exam elucidated the neoformed bone architecture and its components. The efficacy of the techinique was proved and it could be reproduced for many purposes in orthopedic surgery.

  14. Experimental model of a bone gap by radial ostectomy in rabbits

    Directory of Open Access Journals (Sweden)

    Antonio Carlos Cunha Lacreta Junior

    2010-01-01

    Full Text Available A lot of experimental models have been used to study the process of a fracture's consolidation, but the problem is that due to anatomic, biologic and technical differences, these models do not always  have appropriate parameters for the exact species, for which the experiment was done. The rabbit is an experimental model that is widely used in studies involving bone physiopatology in the face of fractures and their different types of treatment, corresponding to approximately 35% of all the musculoskeletic system's scientific studies. Several surgical techniques have been used on rabbit's bone for experimental studies, and the partial ostectomy of the radius bone is one of them. In this study, 14 rabbits (Oryctolagus cuniculus familiaris, males, adults, of white New Zeland breed, neutered, with weight between three and four kilograms, were used. Clinically, the animals did not present any alterations that compromised the study. There were evaluated through radiographic exam on days zero, 30 and 60 after the surgery, visualizing the quality of the gap and the relevant alteration of bone proliferation. The histologic exam elucidated the neoformed bone architecture and its components. The efficacy of the techinique was proved and it could be reproduced for many purposes in orthopedic surgery.

  15. An animal model in sheep for biocompatibility testing of biomaterials in cancellous bones

    Directory of Open Access Journals (Sweden)

    Boos Alois

    2006-08-01

    Full Text Available Abstract Background The past years have seen the development of many synthetic bone replacements. To test their biocompatibility and ability for osseointegration, osseoinduction and -conduction requires their placement within bone preferably in an animal experiment of a higher species. Methods A suitable experimental animal model in sheep with drill holes of 8 mm diameter and 13 mm depth within the proximal and distal humerus and femur for testing biocompatibility issues is introduced. Results This present sheep model allows the placing of up to 8 different test materials within one animal and because of the standardization of the bone defect, routine evaluation by means of histomorphometry is easily conducted. This method was used successfully in 66 White Alpine Sheep. When the drill holes were correctly placed no complications such as spontaneous fractures were encountered. Conclusion This experimental animal model serves an excellent basis for testing the biocompatibility of novel biomaterials to be used as bone replacement or new bone formation enhancing materials.

  16. Modeling elite male athletes' peripheral bone mass, assessed using regional dual x-ray absorptiometry.

    Science.gov (United States)

    Nevill, A M; Holder, R L; Stewart, A D

    2003-01-01

    There is still considerable debate as to whether bone mineral content (BMC) increases in proportion to the projected bone area, A(p), or an estimate of the skeletal bone volume, (A(p))(3/2), being assessed. The results from this study suggest that the bone mass acquisition of elite athletes' arms and legs increases in proportion to the projected bone area, A(p), having simultaneously controlled/removed the effect of the confounding variables of body mass and body fat. Although this supports the use of the traditional bone mineral density ratio (BMD=BMC/A(p)), it also highlights the dangers of overlooking the effect of known confounding variables. Ignoring the effect of such confounding variables, athletic groups whose activities involve upper body strength (rugby, rock climbing, kayaking, weight lifting) had the highest arm BMD, while runners were observed to have the lowest arm BMD (lower than that of the controls). Similarly, leg BMD was highest in rugby players, whose activities included both running and strength training. However, the rugby players were also observed to have the greatest body mass. When the important determinants of body mass, body fat, as well as projected bone area, A(p), were incorporated as covariates into a proportional allometric ANCOVA model for BMC, different conclusions were obtained. The introduction of these covariates had the effect of reducing the sporting differences on adjusted arm BMC, although the "sport" by "side" interaction still identified racket players as the only group with a greater dominant arm BMC (P benefits of activity on peripheral bone mass as being site-specific but reinforce the dangers of making generalizations about the relative benefits of different exercises ignoring the effects of known confounding variables, such as body size, body composition, and age.

  17. Degradation pattern of a porcine collagen membrane in an in vivo model of guided bone regeneration.

    Science.gov (United States)

    Calciolari, E; Ravanetti, F; Strange, A; Mardas, N; Bozec, L; Cacchioli, A; Kostomitsopoulos, N; Donos, N

    2018-02-15

    Although collagen membranes have been clinically applied for guided tissue/bone regeneration for more than 30 years, their in vivo degradation pattern has never been fully clarified. A better understanding of the different stages of in vivo degradation of collagen membranes is extremely important, considering that the biology of bone regeneration requires the presence of a stable and cell/tissue-occlusive barrier during the healing stages in order to ensure a predictable result. Therefore, the aim of this study was to investigate the degradation pattern of a porcine non-cross-linked collagen membrane in an in vivo model of guided bone regeneration (GBR). Decalcified and paraffin-embedded specimens from calvarial defects of 18, 10-month-old Wistar rats were used. The defects were treated with a double layer of collagen membrane and a deproteinized bovine bone mineral particulate graft. At 7, 14 and 30 days of healing, qualitative evaluation with scanning electron microscopy and atomic force microscopy, and histomorphometric measurements were performed. Markers of collagenase activity and bone formation were investigated using an immunofluorescence technique. A significant reduction of membrane thickness was observed from 7 to 30 days of healing, which was associated with progressive loss of collagen alignment, increased collagen remodeling and progressive invasion of woven bone inside the membranes. A limited inflammatory infiltrate was observed at all time points of healing. The collagen membrane investigated was biocompatible and able to promote bone regeneration. However, pronounced signs of degradation were observed starting from day 30. Since successful regeneration is obtained only when cell occlusion and space maintenance exist for the healing time needed by the bone progenitor cells to repopulate the defect, the suitability of collagen membranes in cases where long-lasting barriers are needed needs to be further reviewed. © 2018 John Wiley & Sons A

  18. Effects of atomic-level nano-structured hydroxyapatite on adsorption of bone morphogenetic protein-7 and its derived peptide by computer simulation

    OpenAIRE

    Wang, Qun; Wang, Menghao; Lu, Xiong; Wang, Kefeng; Fang, Liming; Ren, Fuzeng; Lu, Guoming

    2017-01-01

    Hydroxyapatite (HA) is the principal inorganic component of bones and teeth and has been widely used as a bone repair material because of its good biocompatibility and bioactivity. Understanding the interactions between proteins and HA is crucial for designing biomaterials for bone regeneration. In this study, we evaluated the effects of atomic-level nano-structured HA (110) surfaces on the adsorption of bone morphogenetic protein-7 (BMP-7) and its derived peptide (KQLNALSVLYFDD) using molecu...

  19. Osteoinductivity of gelatin/β-tricalcium phosphate sponges loaded with different concentrations of mesenchymal stem cells and bone morphogenetic protein-2 in an equine bone defect model.

    Science.gov (United States)

    Seo, Jong-Pil; Tsuzuki, Nao; Haneda, Shingo; Yamada, Kazutaka; Furuoka, Hidefumi; Tabata, Yasuhiko; Sasaki, Naoki

    2014-03-01

    Fracture is one of the most life-threatening injuries in horses. Fracture repair is often associated with unsatisfactory outcomes and is associated with a high incidence of complications. This study aimed to evaluate the osteogenic effects of gelatin/β-tricalcium phosphate (GT) sponges loaded with different concentrations/ratios of mesenchymal stem cells (MSCs) and bone morphogenetic protein-2 (BMP-2) in an equine bone defect model. Seven thoroughbred horses were used in this study. Eight bone defects were created in the third metatarsal bones of each horse. Then, eight treatments, namely control, GT, GT/M-5, GT/M-6, GT/M-5/B-1, GT/M-5/B-3, GT/M-6/B-1, and GT/M-6/B-3 were applied to the eight different sites in a randomized manner (M-5: 2 × 10(5) MSCs; M-6: 2 × 10(6) MSCs; B-1: 1 μg of BMP-2; B-3: 3 μg of BMP-2). Repair of bone defects was assessed by radiography, quantitative computed tomography (QCT), and histopathological evaluation. Radiographic scores and CT values were significantly lower in the control group than in the other groups, while they were significantly higher in the GT/M-5/B-3 and GT/M-6/B-3 groups than in the other groups. The amount of mature compact bone filling the defects was greater in the GT/M-5/B-3 and GT/M-6/B-3 groups than in the other groups. The present study demonstrated that the GT sponge loaded with MSCs and BMP-2 promoted bone regeneration in an equine bone defect model. The GT/MSC/BMP-2 described here may be useful for treating horses with bone injuries.

  20. Evaluation of pharmaceuticals with a novel 50-hour animal model of bone loss.

    Science.gov (United States)

    Tomimori, Yoshiya; Mori, Kaoru; Koide, Masanori; Nakamichi, Yuko; Ninomiya, Tadashi; Udagawa, Nobuyuki; Yasuda, Hisataka

    2009-07-01

    Osteoporosis remains a major public health problem through its associated fragility fractures. Several animal models for the study of osteoporotic bone loss, such as ovariectomy (OVX) and denervation, require surgical skills and several weeks to establish. Osteoclast differentiation and activation is mediated by RANKL. Here we report the establishment of a novel and rapid bone loss model by the administration of soluble RANKL (sRANKL) to mice. Mice were injected intraperitoneally with sRANKL and used to evaluate existing anti-osteoporosis drugs. sRANKL decreased BMD within 50 h in a dose-dependent manner. The marked decrease in femoral trabecular BMD shown by pQCT and the 3D images obtained by microCT were indistinguishable from those observed in the OVX model. Histomorphometry showed that osteoclastic activity was significantly increased in the sRANKL-injected mice. In addition, serum biochemical markers of bone turnover such as Ca, C-telopeptide of type 1 collagen (CTX), and TRACP5b were also significantly increased in the sRANKL-injected mice in a dose-dependent manner. Bisphosphonates (BPs), selective estrogen receptor modulators (SERMs), and PTH are commonly used for the treatment of osteoporosis. We successfully evaluated the effects of anti-bone-resorbing agents such as BPs, a SERM, and anti-RANKL-neutralizing antibody on bone resorption in a couple of weeks. We also evaluated the effects of PTH on bone formation in 2 wk. A combination of sRANKL injections and OVX made it possible to evaluate a SERM. The sRANKL model is the simplest, fastest, and easiest of all osteoporosis models and could be useful in the evaluation of drug candidates for osteoporosis.

  1. An over-nonlocal implicit gradient-enhanced damage-plastic model for trabecular bone under large compressive strains.

    Science.gov (United States)

    Hosseini, Hadi S; Horák, Martin; Zysset, Philippe K; Jirásek, Milan

    2015-11-01

    Investigation of trabecular bone strength and compaction is important for fracture risk prediction. At 1-2% compressive strain, trabecular bone undergoes strain softening, which may lead to numerical instabilities and mesh dependency in classical local damage-plastic models. The aim of this work is to improve our continuum damage-plastic model of bone by reducing the influence of finite element mesh size under large compression. This spurious numerical phenomenon may be circumvented by incorporating the nonlocal effect of cumulated plastic strain into the constitutive law. To this end, an over-nonlocal implicit gradient model of bone is developed and implemented into the finite element software ABAQUS using a user element subroutine. The ability of the model to detect the regions of bone failure is tested against experimental stepwise loading data of 16 human trabecular bone biopsies. The numerical outcomes of the nonlocal model revealed reduction of finite element mesh dependency compared with the local damage-plastic model. Furthermore, it helped reduce the computational costs of large-strain compression simulations. To the best of our knowledge, the proposed model is the first to predict the failure and densification of trabecular bone up to large compression independently of finite element mesh size. The current development enables the analysis of trabecular bone compaction as in osteoporotic fractures and implant migration, where large deformation of bone plays a key role. Copyright © 2015 John Wiley & Sons, Ltd.

  2. A quantification strategy for missing bone mass in case of osteolytic bone lesions

    International Nuclear Information System (INIS)

    Fränzle, Andrea; Giske, Kristina; Bretschi, Maren; Bäuerle, Tobias; Hillengass, Jens; Bendl, Rolf

    2013-01-01

    Purpose: Most of the patients who died of breast cancer have developed bone metastases. To understand the pathogenesis of bone metastases and to analyze treatment response of different bone remodeling therapies, preclinical animal models are examined. In breast cancer, bone metastases are often bone destructive. To assess treatment response of bone remodeling therapies, the volumes of these lesions have to be determined during the therapy process. The manual delineation of missing structures, especially if large parts are missing, is very time-consuming and not reproducible. Reproducibility is highly important to have comparable results during the therapy process. Therefore, a computerized approach is needed. Also for the preclinical research, a reproducible measurement of the lesions is essential. Here, the authors present an automated segmentation method for the measurement of missing bone mass in a preclinical rat model with bone metastases in the hind leg bones based on 3D CT scans. Methods: The affected bone structure is compared to a healthy model. Since in this preclinical rat trial the metastasis only occurs on the right hind legs, which is assured by using vessel clips, the authors use the left body side as a healthy model. The left femur is segmented with a statistical shape model which is initialised using the automatically segmented medullary cavity. The left tibia and fibula are segmented using volume growing starting at the tibia medullary cavity and stopping at the femur boundary. Masked images of both segmentations are mirrored along the median plane and transferred manually to the position of the affected bone by rigid registration. Affected bone and healthy model are compared based on their gray values. If the gray value of a voxel indicates bone mass in the healthy model and no bone in the affected bone, this voxel is considered to be osteolytic. Results: The lesion segmentations complete the missing bone structures in a reasonable way. The mean

  3. Dating of cremated bones

    NARCIS (Netherlands)

    Lanting, JN; Aerts-Bijma, AT; van der Plicht, J; Boaretto, E.; Carmi, I.

    2001-01-01

    When dating unburnt bone, bone collagen, the organic fraction of the bone, is used. Collagen does not survive the heat of the cremation pyre, so dating of cremated bone has been considered impossible. Structural carbonate in the mineral fraction of the bone, however, survives the cremation process.

  4. [Effect of age and anti-osteoporotic drugs on bone strength and structure of the distal radius].

    Science.gov (United States)

    Uchiyama, Shigeharu

    2013-07-01

    The distal radius constitutes a proximal part of the wrist joint, which bears axial load from the carpal bones. Based on the biomechanical experiments, the load transmitted from the carpal bones to the distal articular surface of the radius is greater to the lunate fossa than the scaphoid fossa. The findings are consistent with the results obtained from HR-pQCT analysis of the distal radius. As ageing, bone mineral densities of the distal radius decrease, and structures of the cortical and trabecular bones also deteriorate. Such deterioration can be prevented by osteoporotic medicines such as PTH or bisphosphonate. Denosumab has been shown to increase mechanical indices of the bone structure of the distal radius. The distal radius of the individual is fractured when the load over approximately 5 times (2.5SD) of the weight is applied. It is possible to predict load of fracture in the distal radius from the results of DXA derived BMD or HR-pQCT derived bone parameters. We should not miss the opportunity of treatment for osteoporosis when the patients with fragility distal radius fracture are seen.

  5. Third metacarpal condylar fatigue fractures in equine athletes occur within previously modelled subchondral bone.

    Science.gov (United States)

    Whitton, R Christopher; Trope, Gareth D; Ghasem-Zadeh, Ali; Anderson, Garry A; Parkin, Timothy D H; Mackie, Eleanor J; Seeman, Ego

    2010-10-01

    Bone modelling and remodelling reduce the risk of fatigue fractures; the former by adapting bone to its loading circumstances, the latter by replacing fatigued bone. Remodelling transiently increases porosity because of the normal delay in onset of the formation phase of the remodelling sequence. Protracted intense loading suppresses remodelling leaving modelling as the only means of maintaining bone strength. We therefore hypothesized that race horses with fatigue fractures of the distal third metacarpal bone (MC3) will have reduced porosity associated with suppressed remodelling while continued adaptive modelling will result in higher volume fraction (BV/TV) at this site. Using high resolution peripheral quantitative computed tomography (HR-pQCT), we measured the distal aspect of the MC3 obtained at postmortem from 13 thoroughbred race horses with condylar fractures of the MC3 (cases), 8 horses without fractures (training controls), 14 horses with a fracture at another site (fractured controls) and 9 horses resting from training (resting controls). Porosity of the subchondral bone of MC3 was lower in cases than resting controls (12±1.4% vs. 18±1.6%, P=0.017) although areas of focal porosity were observed adjacent to fractures in 6/13 horses. BV/TV of the distal metacarpal epiphysis tended to be higher in horses with condylar fractures (0.79±0.015) than training controls (0.74±0.019, P=0.070), but also higher in controls with a fracture elsewhere (0.79±0.014) than the training controls (0.74±0.019, P=0.040). BV/TV was higher in horses over three years of age than those aged two or three years (0.79±0.01 vs. 0.74±0.01, P=0.016). All metacarpal condylar fractures occurred within focal areas of high BV/TV. We infer that intense training in equine athletes suppresses remodelling of third metacarpal subchondral bone limiting damage repair while modelling increases regional bone volume in an attempt to minimise local stresses but may fail to offset bone

  6. Structural properties of a bone-ceramic composite as a promising material in spinal surgery

    Energy Technology Data Exchange (ETDEWEB)

    Kirilova, I. A., E-mail: IKirilova@mail.ru; Sadovoy, M. A.; Podorozhnaya, V. T., E-mail: VPodorognaya@niito.ru; Taranov, O. S. [Novosibirsk Research Institute of Traumatology and Orthopedics n.a. Ya.L. Tsivyan, Novosibirsk (Russian Federation); Klinkov, S. V.; Kosarev, V. F. [Christianovich Institute of Theoretical and Applied Mechanics, SB RAS, Novosibirsk (Russian Federation); Shatskaya, S. S. [Institute of Solid State Chemistry and Mechanochemistry, SB RAS, Novosibirsk (Russian Federation)

    2015-11-17

    The paper describes the results of in vitro tests of composite bone-ceramic implants and procedures for modifying implant surfaces to enhance osteogenesis. Analysis of CBCI ESs demonstrated that they have a porous structure with the mean longitudinal pore size of 70 µm and the mean transverse pore size of 46 µm; surface pores are open, while inner pores are closed. Elemental analysis of the CBCI surface demonstrates that CBCIs are composed of aluminum and zirconium oxides and contain HA inclusions. Profilometry of the CBCI ES surface revealed the following deviations: the maximum deviation of the profile in the sample center is 15 µm and 16 µm on the periphery, while the arithmetical mean and mean square deviations of the profile are 2.65 and 3.4 µm, respectively. In addition, CBCI biodegradation products were pre-examined; a 0.9% NaCl solution was used as a comparison group. Potentially toxic and tissue accumulated elements, such as cadmium, cobalt, mercury, and lead, are present only in trace amounts and have no statistically significant differences with the comparison group, which precludes their potential toxic effects on the macroorganism. Ceramic-based CBCI may be effective and useful in medicine for restoration of the anatomic integrity and functions of the bone tissue.

  7. Paramytha ossicola sp. nov. (Polychaeta, Ampharetidae) from mammal bones: Reproductive biology and population structure

    Science.gov (United States)

    Queirós, José Pedro; Ravara, Ascensão; Eilertsen, Mari H.; Kongsrud, Jon A.; Hilário, Ana

    2017-03-01

    Sunken whale carcasses, known as "whale falls", deliver large, but relatively ephemeral pulses of organic material to the seafloor and serve as habitat for unique assemblages of deep-sea fauna that include generalist-scavenging species, chemosynthetic fauna and bone-specialist species. Despite the great deal of interest that fauna associated with whale falls have attracted, very little is known about this fauna in the deep Atlantic Ocean. Here we describe a new species of Ampharetidae that was found in an experiment using cow carcasses in the Setúbal Canyon (NE Atlantic), as a surrogate of a whale fall. Further, we analyse the size and structure of the population at two different times and use histological analyses to investigate the reproductive biology of this new species. We propose that Paramytha ossicola sp. nov. is a bone-specialist adapted for life in ephemeral habitats. Reproductive traits include rapid maturation, continuous and non-synchronous gametogenesis. Recruitment seems to be controlled by habitat availability and biological interactions that result in post-settlement mortality.

  8. Bone Regeneration Using a Mixture of Silicon-Substituted Coral HA and β-TCP in a Rat Calvarial Bone Defect Model

    Directory of Open Access Journals (Sweden)

    Jiyeon Roh

    2016-02-01

    Full Text Available The demand of bone graft materials has been increasing. Among various origins of bone graft materials, natural coral composed of up to 99% calcium carbonate was chosen and converted into hydroxyapatite (HA; silicon was then substituted into the HA. Then, the Si-HA was mixed with β-tricalcium phosphate (TCP in the ratios 100:0 (S100T0, 70:30 (S70T30, 60:40 (S60T40, and 50:50 (S50T50. The materials were implanted for four and eight weeks in a rat calvarial bone defect model (8 mm. The MBCPTM (HA:β-TCP = 60:40, Biomatalante, Vigneux de Bretagne, France was used as a control. After euthanasia, the bone tissue was analyzed by making histological slides. From the results, S60T40 showed the fastest bone regeneration in four weeks (p < 0.05. In addition, S60T40, S50T50, and MBCPTM showed significant new bone formation in eight weeks (p < 0.05. In conclusion, Si-HA/TCP showed potential as a bone graft material.

  9. Raloxifene reduces the risk of local alveolar bone destruction in a mouse model of periodontitis combined with systemic postmenopausal osteoporosis.

    Science.gov (United States)

    Ichimaru, Ryota; Tominari, Tsukasa; Yoshinouchi, Shosei; Matsumoto, Chiho; Watanabe, Kenta; Hirata, Michiko; Numabe, Yukihiro; Murphy, Gillian; Nagase, Hideaki; Miyaura, Chisato; Inada, Masaki

    2018-01-01

    Periodontitis is characterized by local inflammation leading to tooth loss and severe destruction of alveolar bone. Raloxifene is a selective estrogen receptor modulator (SERM) that halts estrogen deficiency-induced systemic bone loss in postmenopausal osteoporosis without the side effects of cancer in breast and uterus. In this study, we examined the effects of raloxifene on alveolar bone mass in a mouse model with estrogen deficiency-induced periodontitis. Periodontitis was induced by the injection of lipopolysaccharide (LPS) into the lower gingiva in ovariectomized (OVX) mice, and the alveolar bone and femur bone mineral density (BMD) were analyzed by dual-energy X-ray absorptiometry. To explore the direct osteoclast inhibitory effect of raloxifene, a co-culture system for osteoclast formation and organ culture of alveolar bone was established. When OVX mice were treated with raloxifene, the bone loss in both alveolar bone and femur were abrogated. Interleukin 1 and/or LPS stimulated the osteoclast formation and bone-resorbing activity; however, raloxifene did not show any inhibitory effect on the osteoclast formation or function. In vivo local injection of raloxifene also did not prevent bone resorption in a mouse model of periodontitis. However, the systemic treatment of raloxifene using a mini-osmotic pump did prevent the loss of BMD of alveolar bone induced by LPS. These results suggest that the SERM raloxifene systemically maintain alveolar bone mass in a mouse model of periodontitis with osteoporosis. Increasing the alveolar bone mass by SERMs treatment in patients with postmenopausal osteoporosis may be a useful approach to preventing the destruction of alveolar bone in late-onset periodontitis. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Dual Delivery of rhPDGF-BB and Bone Marrow Mesenchymal Stromal Cells Expressing the BMP2 Gene Enhance Bone Formation in a Critical-Sized Defect Model

    Science.gov (United States)

    Park, Shin-Young; Kim, Kyoung-Hwa; Shin, Seung-Yun; Koo, Ki-Tae; Lee, Yong-Moo

    2013-01-01

    Bone tissue healing is a dynamic, orchestrated process that relies on multiple growth factors and cell types. Platelet-derived growth factor-BB (PDGF-BB) is released from platelets at wound sites and induces cellular migration and proliferation necessary for bone regeneration in the early healing process. Bone morphogenetic protein-2 (BMP-2), the most potent osteogenic differentiation inducer, directs new bone formation at the sites of bone defects. This study evaluated a combinatorial treatment protocol of PDGF-BB and BMP-2 on bone healing in a critical-sized defect model. To mimic the bone tissue healing process, a dual delivery approach was designed to deliver the rhPDGF-BB protein transiently during the early healing phase, whereas BMP-2 was supplied by rat bone marrow stromal cells (BMSCs) transfected with an adenoviral vector containing the BMP2 gene (AdBMP2) for prolonged release throughout the healing process. In in vitro experiments, the dual delivery of rhPDGF-BB and BMP2 significantly enhanced cell proliferation. However, the osteogenic differentiation of BMSCs was significantly suppressed even though the amount of BMP-2 secreted by the AdBMP2-transfected BMSCs was not significantly affected by the rhPDGF-BB treatment. In addition, dual delivery inhibited the mRNA expression of BMP receptor type II and Noggin in BMSCs. In in vivo experiments, critical-sized calvarial defects in rats showed enhanced bone regeneration by dual delivery of autologous AdBMP2-transfected BMSCs and rhPDGF-BB in both the amount of new bone formed and the bone mineral density. These enhancements in bone regeneration were greater than those observed in the group treated with AdBMP2-transfected BMSCs alone. In conclusion, the dual delivery of rhPDGF-BB and AdBMP2-transfected BMSCs improved the quality of the regenerated bone, possibly due to the modulation of PDGF-BB on BMP-2-induced osteogenesis. PMID:23901900

  11. Infant bone age estimation based on fibular shaft length: model development and clinical validation

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, Andy; Stamoulis, Catherine; Bixby, Sarah D.; Breen, Micheal A.; Connolly, Susan A.; Kleinman, Paul K. [Boston Children' s Hospital, Harvard Medical School, Department of Radiology, Boston, MA (United States)

    2016-03-15

    Bone age in infants (<1 year old) is generally estimated using hand/wrist or knee radiographs, or by counting ossification centers. The accuracy and reproducibility of these techniques are largely unknown. To develop and validate an infant bone age estimation technique using fibular shaft length and compare it to conventional methods. We retrospectively reviewed negative skeletal surveys of 247 term-born low-risk-of-abuse infants (no persistent child protection team concerns) from July 2005 to February 2013, and randomized them into two datasets: (1) model development (n = 123) and (2) model testing (n = 124). Three pediatric radiologists measured all fibular shaft lengths. An ordinary linear regression model was fitted to dataset 1, and the model was evaluated using dataset 2. Readers also estimated infant bone ages in dataset 2 using (1) the hemiskeleton method of Sontag, (2) the hemiskeleton method of Elgenmark, (3) the hand/wrist atlas of Greulich and Pyle, and (4) the knee atlas of Pyle and Hoerr. For validation, we selected lower-extremity radiographs of 114 normal infants with no suspicion of abuse. Readers measured the fibulas and also estimated bone ages using the knee atlas. Bone age estimates from the proposed method were compared to the other methods. The proposed method outperformed all other methods in accuracy and reproducibility. Its accuracy was similar for the testing and validating datasets, with root-mean-square error of 36 days and 37 days; mean absolute error of 28 days and 31 days; and error variability of 22 days and 20 days, respectively. This study provides strong support for an infant bone age estimation technique based on fibular shaft length as a more accurate alternative to conventional methods. (orig.)

  12. First Reported Cases of Biomechanically Adaptive Bone Modeling in Non-Avian Dinosaurs.

    Science.gov (United States)

    Cubo, Jorge; Woodward, Holly; Wolff, Ewan; Horner, John R

    2015-01-01

    Predator confrontation or predator evasion frequently produces bone fractures in potential prey in the wild. Although there are reports of healed bone injuries and pathologies in non-avian dinosaurs, no previously published instances of biomechanically adaptive bone modeling exist. Two tibiae from an ontogenetic sample of fifty specimens of the herbivorous dinosaur Maiasaura peeblesorum (Ornithopoda: Hadrosaurinae) exhibit exostoses. We show that these outgrowths are cases of biomechanically adaptive periosteal bone modeling resulting from overstrain on the tibia after a fibula fracture. Histological and biomechanical results are congruent with predictions derived from this hypothesis. Histologically, the outgrowths are constituted by radial fibrolamellar periosteal bone tissue formed at very high growth rates, as expected in a process of rapid strain equilibration response. These outgrowths show greater compactness at the periphery, where tensile and compressive biomechanical constraints are higher. Moreover, these outgrowths increase the maximum bending strength in the direction of the stresses derived from locomotion. They are located on the antero-lateral side of the tibia, as expected in a presumably bipedal one year old individual, and in the posterior position of the tibia, as expected in a presumably quadrupedal individual at least four years of age. These results reinforce myological evidence suggesting that Maiasaura underwent an ontogenetic shift from the primitive ornithischian bipedal condition when young to a derived quadrupedal posture when older.

  13. First Reported Cases of Biomechanically Adaptive Bone Modeling in Non-Avian Dinosaurs.

    Directory of Open Access Journals (Sweden)

    Jorge Cubo

    Full Text Available Predator confrontation or predator evasion frequently produces bone fractures in potential prey in the wild. Although there are reports of healed bone injuries and pathologies in non-avian dinosaurs, no previously published instances of biomechanically adaptive bone modeling exist. Two tibiae from an ontogenetic sample of fifty specimens of the herbivorous dinosaur Maiasaura peeblesorum (Ornithopoda: Hadrosaurinae exhibit exostoses. We show that these outgrowths are cases of biomechanically adaptive periosteal bone modeling resulting from overstrain on the tibia after a fibula fracture. Histological and biomechanical results are congruent with predictions derived from this hypothesis. Histologically, the outgrowths are constituted by radial fibrolamellar periosteal bone tissue formed at very high growth rates, as expected in a process of rapid strain equilibration response. These outgrowths show greater compactness at the periphery, where tensile and compressive biomechanical constraints are higher. Moreover, these outgrowths increase the maximum bending strength in the direction of the stresses derived from locomotion. They are located on the antero-lateral side of the tibia, as expected in a presumably bipedal one year old individual, and in the posterior position of the tibia, as expected in a presumably quadrupedal individual at least four years of age. These results reinforce myological evidence suggesting that Maiasaura underwent an ontogenetic shift from the primitive ornithischian bipedal condition when young to a derived quadrupedal posture when older.

  14. In vivo micro-CT analysis of bone remodeling in a rat calvarial defect model

    Energy Technology Data Exchange (ETDEWEB)

    Umoh, Joseph U; Holdsworth, David W [Pre-Clinical Imaging Research Centre, Robarts Research Institute, Schulich School of Medicine and Dentistry, University of Western Ontario, PO Box 5015, 100 Perth Drive, London, ON N6A 5K8 (Canada); Sampaio, Arthur V; Underhill, T Michael [Laboratory of Molecular Skeletogenesis, Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BC (Canada); Welch, Ian [Animal Care and Veterinary Services, University of Western Ontario, London, ON (Canada); Pitelka, Vasek; Goldberg, Harvey A [CIHR Group in Skeletal Development and Remodelling, University of Western Ontario, London, ON (Canada)], E-mail: jumoh@imaging.robarts.ca, E-mail: asampaio@interchange.ubc.ca, E-mail: tunderhi@interchange.ubc.ca, E-mail: iwelch@uwo.ca, E-mail: vasek.pitelka@schulich.uwo.ca, E-mail: hagoldbe@uwo.ca, E-mail: david.holdsworth@imaging.robarts.ca

    2009-04-07

    The rodent calvarial defect model is commonly used to investigate bone regeneration and wound healing. This study presents a micro-computed tomography (micro-CT) methodology for measuring the bone mineral content (BMC) in a rat calvarial defect and validates it by estimating its precision error. Two defect models were implemented. A single 6 mm diameter defect was created in 20 rats, which were imaged in vivo for longitudinal experiments. Three 5 mm diameter defects were created in three additional rats, which were repeatedly imaged ex vivo to determine precision. Four control rats and four rats treated with bone morphogenetic protein were imaged at 3, 6, 9 and 12 weeks post-surgery. Scan parameters were 80 kVp, 0.45 mA and 180 mAs. Images were reconstructed with an isotropic resolution of 45 {mu}m. At 6 weeks, the BMC in control animals (4.37 {+-} 0.66 mg) was significantly lower (p < 0.05) than that in treated rats (11.29 {+-} 1.01 mg). Linear regression between the BMC and bone fractional area, from 20 rats, showed a strong correlation (r{sup 2} = 0.70, p < 0.0001), indicating that the BMC can be used, in place of previous destructive analysis techniques, to characterize bone growth. The high precision (2.5%) of the micro-CT methodology indicates its utility in detecting small BMC changes in animals.

  15. Fusobacterium nucleatum and Tannerella forsythia Induce Synergistic Alveolar Bone Loss in a Mouse Periodontitis Model

    Science.gov (United States)

    Settem, Rajendra P.; El-Hassan, Ahmed Taher; Honma, Kiyonobu; Stafford, Graham P.

    2012-01-01

    Tannerella forsythia is strongly associated with chronic periodontitis, an inflammatory disease of the tooth-supporting tissues, leading to tooth loss. Fusobacterium nucleatum, an opportunistic pathogen, is thought to promote dental plaque formation by serving as a bridge bacterium between early- and late-colonizing species of the oral cavity. Previous studies have shown that F. nucleatum species synergize with T. forsythia during biofilm formation and pathogenesis. In the present study, we showed that coinfection of F. nucleatum and T. forsythia is more potent than infection with either species alone in inducing NF-κB activity and proinflammatory cytokine secretion in monocytic cells and primary murine macrophages. Moreover, in a murine model of periodontitis, mixed infection with the two species induces synergistic alveolar bone loss, characterized by bone loss which is greater than the additive alveolar bone losses induced by each species alone. Further, in comparison to the single-species infection, mixed infection caused significantly increased inflammatory cell infiltration in the gingivae and osteoclastic activity in the jaw bones. These data show that F. nucleatum subspecies and T. forsythia synergistically stimulate the host immune response and induce alveolar bone loss in a murine experimental periodontitis model. PMID:22547549

  16. Development of 3D printing system for human bone model manufacturing using medical images

    International Nuclear Information System (INIS)

    Oh, Wang Kyun

    2017-01-01

    The 3D printing selective laser sintering (SLS) and stereo lithography apparatus (SLA) method used for bone model production has good precision and resolution, but the printers are expensive and need professional knowledge for operation. The program that converts computed tomography digital imaging and communications in medicine (DICOM) file into STL (stereolithography) file is also expensive so requesting 3D printing companies takes a lot of time and cost, which is why they are not generally utilized in surgery. To produce bone models of fractured patients, the use of 3D imaging conversion program and 3D printing system should be convenient, and the cost of device and operation should be low. Besides, they should be able to produce big size bone models for application to surgery. Therefore, by using an fused deposition modeling (FDM) method 3D printer that uses thermoplastic materials such as DICOM Viewer OsiriX and plastic wires, this study developed 3D printing system for Fracture surgery Patients customized bone model production for many clinics to use for surgery of fracture patients by universalizing with no limit in printing sizes and low maintenance and production cost. It is expected to be widely applied to the overall areas of orthopedics' education, research and clinic. It is also expected to be conveniently used in not only university hospitals but also regular general hospitals

  17. Prefabrication of axial vascularized tissue engineering coral bone by an arteriovenous loop: A better model

    Energy Technology Data Exchange (ETDEWEB)

    Dong Qingshan [Department of Oral and Maxillofacial Surgery, Wuhan General Hospital of Guangzhou Military Command, Wuhan 430070 (China); Shang Hongtao; Wu Wei [Department of Oral and Maxillofacial Surgery, School of Stomatology, Fourth Military Medical University, Xi' an 710032 (China); Chen Fulin [Lab of Tissue Engineering, Faculty of Life Science, Northwest University, Xi' an 710069 (China); Zhang Junrui [Department of Oral and Maxillofacial Surgery, School of Stomatology, Fourth Military Medical University, Xi' an 710032 (China); Guo Jiaping [Department of Oral and Maxillofacial Surgery, Wuhan General Hospital of Guangzhou Military Command, Wuhan 430070 (China); Mao Tianqiu, E-mail: tianqiumao@126.com [Department of Oral and Maxillofacial Surgery, School of Stomatology, Fourth Military Medical University, Xi' an 710032 (China)

    2012-08-01

    The most important problem for the survival of thick 3-dimensional tissues is the lack of vascularization in the context of bone tissue engineering. In this study, a modified arteriovenous loop (AVL) was developed to prefabricate an axial vascularized tissue engineering coral bone in rabbit, with comparison of the arteriovenous bundle (AVB) model. An arteriovenous fistula between rabbit femoral artery and vein was anastomosed to form an AVL. It was placed in a circular side groove of the coral block. The complex was wrapped with an expanded-polytetrafluoroethylene membrane and implanted beneath inguinal skin. After 2, 4, 6 and 8 weeks, the degree of vascularization was evaluated by India ink perfusion, histological examination, vascular casts, and scanning electron microscopy images of vascular endangium. Newly formed fibrous tissues and vasculature extended over the surfaces and invaded the interspaces of entire coral block. The new blood vessels robustly sprouted from the AVL. Those invaginated cavities in the vascular endangium from scanning electron microscopy indicated vessel's sprouted pores. Above indexes in AVL model are all superior to that in AVB model, indicating that the modified AVL model could more effectively develop vascularization in larger tissue engineering bone. - Highlights: Black-Right-Pointing-Pointer A modified arteriovenous loop (AVL) model in rabbit was developed in this study. Black-Right-Pointing-Pointer Axial prevascularization was induced in a larger coral block by using the AVL. Black-Right-Pointing-Pointer The prefabrication of axial vascularized coral bone is superior as vascular carrier.

  18. Development of 3D printing system for human bone model manufacturing using medical images

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Wang Kyun [Dept. of Radiology, Chungcheongbuk-do Cheongju Medical Center, Cheongju (Korea, Republic of)

    2017-09-15

    The 3D printing selective laser sintering (SLS) and stereo lithography apparatus (SLA) method used for bone model production has good precision and resolution, but the printers are expensive and need professional knowledge for operation. The program that converts computed tomography digital imaging and communications in medicine (DICOM) file into STL (stereolithography) file is also expensive so requesting 3D printing companies takes a lot of time and cost, which is why they are not generally utilized in surgery. To produce bone models of fractured patients, the use of 3D imaging conversion program and 3D printing system should be convenient, and the cost of device and operation should be low. Besides, they should be able to produce big size bone models for application to surgery. Therefore, by using an fused deposition modeling (FDM) method 3D printer that uses thermoplastic materials such as DICOM Viewer OsiriX and plastic wires, this study developed 3D printing system for Fracture surgery Patients customized bone model production for many clinics to use for surgery of fracture patients by universalizing with no limit in printing sizes and low maintenance and production cost. It is expected to be widely applied to the overall areas of orthopedics' education, research and clinic. It is also expected to be conveniently used in not only university hospitals but also regular general hospitals.

  19. Prefabrication of axial vascularized tissue engineering coral bone by an arteriovenous loop: A better model

    International Nuclear Information System (INIS)

    Dong Qingshan; Shang Hongtao; Wu Wei; Chen Fulin; Zhang Junrui; Guo Jiaping; Mao Tianqiu

    2012-01-01

    The most important problem for the survival of thick 3-dimensional tissues is the lack of vascularization in the context of bone tissue engineering. In this study, a modified arteriovenous loop (AVL) was developed to prefabricate an axial vascularized tissue engineering coral bone in rabbit, with comparison of the arteriovenous bundle (AVB) model. An arteriovenous fistula between rabbit femoral artery and vein was anastomosed to form an AVL. It was placed in a circular side groove of the coral block. The complex was wrapped with an expanded-polytetrafluoroethylene membrane and implanted beneath inguinal skin. After 2, 4, 6 and 8 weeks, the degree of vascularization was evaluated by India ink perfusion, histological examination, vascular casts, and scanning electron microscopy images of vascular endangium. Newly formed fibrous tissues and vasculature extended over the surfaces and invaded the interspaces of entire coral block. The new blood vessels robustly sprouted from the AVL. Those invaginated cavities in the vascular endangium from scanning electron microscopy indicated vessel's sprouted pores. Above indexes in AVL model are all superior to that in AVB model, indicating that the modified AVL model could more effectively develop vascularization in larger tissue engineering bone. - Highlights: ► A modified arteriovenous loop (AVL) model in rabbit was developed in this study. ► Axial prevascularization was induced in a larger coral block by using the AVL. ► The prefabrication of axial vascularized coral bone is superior as vascular carrier.

  20. Evaluation of rhBMP-2/collagen/TCP-HA bone graft with and without bone marrow cells in the canine femoral multi defect model.

    Science.gov (United States)

    Luangphakdy, V; Shinohara, K; Pan, H; Boehm, C; Samaranska, A; Muschler, G F

    2015-01-12

    Recombinant human bone morphogenetic protein-2, when applied to an absorbable type 1 bovine collagen sponge (rhBMP-2/ACS) is an effective therapy in many bone grafting settings. Bone marrow aspirate (BMA) has also been used as a source of transplantable osteogenic connective tissue progenitors. This study was designed to characterize the performance of a scaffold comprising rhBMP-2/ACS in which the sponge wraps around tri-calcium phosphate hydroxyapatite granules (rhBMP-2/ACS/TCP-HA) and to test the hypothesis that addition of BMA will improve the performance of this construct in the Canine Femoral Multi Defect Model. In each subject, two sites were grafted with rhBMP-2/ACS/TCP-HA scaffold loaded with BMA clot and two other sites with rhBMP-2/ACS/TCP-HA scaffold loaded with wound blood (WB). After correction for unresorbed TCP-HA granules, sites grafted with rhBMP-2/ACS/TCP-HA+BMA and rhBMP-2/ACS/TCP-HA+WB were similar, with mean percent bone volumes of 10.9 %±1.2 and 11.2 %±1.2, respectively. No differences were seen in quantitative histomorphometry. While bone formation using both constructs was robust, this study did not support the hypothesis that the addition of unprocessed bone marrow aspirate clot improved bone regeneration in a site engrafted with rhBMP-2/ACS/TCP-HA+BMA. In contrast to prior studies using this model, new bone formation was greater at the center of the defect where TCP-HA was distributed. This finding suggests a potential synergy between rhBMP-2 and the centrally placed ceramic and cellular components of the graft construct. Further optimization may also require more uniform distribution of TCP-HA, alternative cell delivery strategies, and a more rigorous large animal segmental defect model.