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Sample records for cultured trabecular meshwork

  1. Dexamethasone induced ultrastructural changes in cultured human trabecular meshwork cells.

    Science.gov (United States)

    Wilson, K; McCartney, M D; Miggans, S T; Clark, A F

    1993-09-01

    Glucocorticoid-induced ocular hypertension has been demonstrated in both animals and humans. It is possible that glucocorticoid-induced changes in trabecular meshwork (TM) cells are responsible for this hypertension. In order to elaborate further the effect of glucocorticoids on the trabecular meshwork, the ultrastructural consequences of dexamethasone (DEX) treatment were examined in three different human TM cell lines. Confluent TM cells were treated with 0.1 microM of DEX for 14 days, and then processed for light, epifluorescent microscopy or transmission electron microscopy (TEM). The effect of DEX treatment on TM cell and nuclear size was quantified using computer assisted morphometrics. Morphometric analysis showed a significant increase in both TM cell and nuclear size after 14 days of DEX treatment. Epifluorescent microscopy of rhodamine-phalloidin stained, control TM cells showed the normal arrangement of stress fibers. In contrast, DEX-treated TM cells showed unusual geodesic dome-like cross-linked actin networks. Control TM cells had the normal complement and arrangement of organelles as well as electron dense inclusions and large vacuoles. DEX-treated TM cells showed stacked arrangements of smooth and rough endoplasmic reticulum, proliferation of the Golgi apparatus, pleomorphic nuclei and increased amounts of extracellular matrix material. The DEX-induced alterations observed in the present study may be an indication of the processes that are occurring in the in vivo disease process.

  2. A Study of Toxic Effect of Mitomycin C on Cultured Bovine Trabecular Meshwork Cells

    Institute of Scientific and Technical Information of China (English)

    Fagang Jiang; Houren Wei; Yuanshu Lu; Ying Zhang; Yuanqing Zhou

    2000-01-01

    Purpose: To explore the toxicity of Mitomycin C (MMC) on trabecular meshwork cells.Methods: Bovine trabecular meshwork cells were cultured in vitro and exposed to MMC of different concentrations. The cellular morphology, ultrastructure, mortality and phagocytosis was studied with light microscopy, transmission electron microscopy and methods of Wright's stain, etc.Results: It was found that the toxic effect of MMC on the cells was in a dose-dependent mode. 1 × 10-2 and 1 × 10-3mg/ml of MMC caused a large part of cells dead, 1 × 10-4 and 1 × 10-5mg/ml of the drug had remarkable killing effect on the cells. 1 × 10-6mg/ml of MMC had still a mild toxicity, while 1 × 10-7 mg/ml of MMC had not any influence on cellular morphology, mortality, and phagocytosis, etc. The safe concentration on bovine trabecular meshwork cells was 1 × 10-7mg/ml and the LD50 was between 1 × 10-3and 1 × 10-4mg/ml.Conclusions: Refering to previous data, we conclude that conventional clinicalapplication of MMC might do harm to trabecular meshwork cells. Eye Science 2000; 16:38~ 42.

  3. A Study of Toaic Effect of Mitomycin Con Cultured Bovine Trabecular Meshwork Cells

    Institute of Scientific and Technical Information of China (English)

    FagangJiang; HourenWei; 等

    2002-01-01

    Purpose:To explore the toxicity of Mitomycin C(MMC) on trabecular meshwork cells.Methods:Bovine trabecular meshwork cells were cultured in vitro and exposed to MMC of different concentrations.The cellular morphology,ultrastructure,mortality and phagocytosis was studied with light microscopy,transmission electron microscopy and methods of Wright's stain,etc.Results:It was found that the toxic effect of MMC on the cells was in a dose-dependent mode.1×10-2 and 1×10-3mg/ml of MMC caused a large part of cells dead,1×10-4 and 1×10-5mg/ml of the drug had remarkable dkilling effect on the cells.1×10-6mg/ml of MMC had still a mild toxicity,while 1×10-7 mg/ml of MMC had not any influence on cellular morphology,mortality,and phagocytosis,etc.The safe concentration on bovine trabecular meshwork cells was 1×10-7mg/ml and the LD50 was between 1×10-3 and 1×10-4mg/ml.Conclusions:Refering to previous data,we conclude that conventional clinical application of MMC might do harm to trabecular meshwork cells.Eye Science 2000;16:38-42.

  4. Adenovirus-mediated Gene Transfer of MMP-2 into Cultured Porcine Trabecular Meshwork Cells

    OpenAIRE

    2012-01-01

    This study aimed to use adenoviral gene transfer to express matrix metalloproteinase (MMP)-2 in cultured porcine trabecular meshwork cells and to evaluate the duration of adenovirus-mediated MMP-2 expression and its enzymatic activity. MMP-2 cDNA was synthesized by ligating three segments of MMP-2 cDNA obtained by reverse transcription-polymerase chain reaction (RT-PCR) with mRNA extracted from mouse lungs. MMP-2 cDNA was inserted into replication-deficient adenoviral vectors. Western blottin...

  5. [Morphopathological changes in glaucoma-induced trabecular meshwork].

    Science.gov (United States)

    Petraru, D; Indrei, Anca; Costin, D; Mihalache, G

    2011-01-01

    Glaucoma causes trabecular meshwork and Schlemm canal changes, resulting in the obstruction of the aqueous flow at this level. To show the histological changes in the surgically removed trabecular meshwork tissues. Trabecular meshwork fragments were histologically processed for histological diagnosis. 29.87% of all patients had ordered structure with high eosinophilia, 20.12% a rare structure with high eosinophilia, 21.34% a voluminous trabecular meshwork with fusiform cells, 21.03% tissue fibrosis and 7.62% had tissue necrosis. Aqueous flow obstruction in trabecular meshwork is produced by the histological changes at this level, found in all tissue specimens removed during surgery.

  6. Antagonistic Effects of Tranilast on Proliferation and Collagen Synthesis Induced by TGF-β2 in Cultured Human Trabecular Meshwork Cells

    Institute of Scientific and Technical Information of China (English)

    笪邦红; 曹阳; 魏厚仁; 陈志新; 水迎波; 李忠玉

    2004-01-01

    Whether tranilast had antagonistic effect on proliferation inhibition and collagen synthesis promotion induced by TGF-β2 in cultured human trabecular meshwork cells was investigated. Suspension of 1 × 104 cultured human trabecular meshwork cells of 3-5 passage was distributed in each well of a 96-well disk and divided into control group and experimental group. After 24 h, 0 μg/ml (control), 12.5 μg/ml, 25 μg/ml, 50 μg/ml tranilast with 3.2 ng/ml TGF-β2 were added into the incubation medium. Another 24 h later, proliferation and collagen synthesis in cultured human trabecular meshwork cells were examined respectively by using tetrazolium-based semiautomated colormetric (MTT) assay and 3 H-proline incorporation with liquid scintillation technique. The results showed absorbance (A) values of the experimental groups were 0. 9036 ± 0. 3017, 1.1361 ±0.1352, 1.2457 ±0.1524 according to the different concentrations of tranilast, and 0. 8956 ±0. 1903 of the control group. In comparison with the control group, 25 μg/ml (q′= 3. 23, P<0.05), 50 μg/ml (q=4.70, P<0.01) tranilast significantly antagonized the decrease of the A values induced by TGF-β2 in the cultured human trabecular meshwork cells. In comparison with the control group [817.37±124.21 cpm/104 cells], 12.5 μg/ml (620.33±80.46 cpm/104 cells, q′=4.26, P<0.05),25 μg/ml (594. 58±88.13 cpm/104 cells, q′=4. 81, P<0.01), 50 μg/ml (418. 64±67.90 cpm/104 cells, q′=8.62, P<0.01) tranilast significantly inhibited the incorporation of 3 H-proline into the cultured human trabecular meshwork cells promoted by TGF-β2 in a dose-dependent manner. It was concluded that tranilast had the antagonistic effect on the proliferation inhibition and collagen synthesis promotion induced by TGF-β2 in the cultured human trabecular meshwork cells.

  7. Dual-purpose laser irradiation and perfusion testing system for in-vitro experiments using cultured trabecular meshwork endothelial cells

    Science.gov (United States)

    Rivera, Brian K.; Roberts, Cynthia J.; Weber, Paul A.

    1998-06-01

    The means by which Argon laser trabeculoplasty (ALT) lowers intraocular pressure (IOP) is a matter of debate. Mechanical and biological laser-tissue interaction theories have been proposed. To investigate the effect laser irradiation has upon the aqueous outflow facility of trabecular meshwork (TM) cells, a suitable in-vitro model is required. Therefore the purpose of this study was to design, construct, and validate a laser irradiation and perfusion testing apparatus. The system was designed to utilize cultured TM cells seeded onto filter supports. Outflow facility will be quantified by calculating the hydraulic conductivity of the monolayer. An appropriate filter support was located, and its perfusion characteristics determined using water. Afterwards, the steady state perfusion flow rate of the filter was ascertained to be 0.096 plus or minus 0.008 ml/min when culture medium is used. Following these tests a single, baseline perfusion experiment was conducted using a TM cell monolayer. Analysis of the data produced a baseline hydraulic conductivity of 0.673 plus or minus 0.076 (mu) l/min/mm Hg/cm2, well within the range found in previous reports. A dual purpose, in vitro-cellular perfusion and laser irradiation testing apparatus has been developed, tested and validates using known baseline cellular perfusion and laser irradiation testing apparatus has been developed, tested, and validated using known baseline cellular perfusion values. Future experiments will be conducted to verify these initial findings, and further experiments will be conducted using Argon laser irradiation. The response of the TM cell monolayer will then be compared to the baseline figures.

  8. Apoptosis of Human Trabecular Meshwork Cells Induced by Transforming Growth Factor-p2 in vitro

    Institute of Scientific and Technical Information of China (English)

    CAO Yang(曹 阳); WEI Houren(魏厚仁); Pfaffl Michael; DA Banghong(笪邦红); LI Zhongyu(李忠玉)

    2004-01-01

    Summary: Whether transforming growth factor-β2 (TGF-β2) induces apoptosis of human trabecular meshwork cells was investigated in vitro. Cultured 3-5 passage human trabecular meshwork cells were treated with 0 (control), 0.32, 1, 3.2 ng/ml TGF-β2 for 48 h and divided into control group and experimental group. The apoptosis of human trabecular meshwork cells was examined by transmisson electron microscopy, TUNEL technique and flow cytometry. The results showed characteristic morphologic changes of apoptotic cells were observed under transmission electron microscopy.DNA fragmentation of human trabecular meshwork cells was found by TUNEL technique. Quantitative analysis of flow cytometry showed that percentages of apoptotic human trabecular meshwork cells were (2.79±0.44) %, (4.43±1.17) % and (9. 60±2.05) % respectively with different concentrations [1 ng/ml (P<0. 05), 3.2 ng/ml (P<0.01)] of TGF-β2 with the difference being significant between experimental group and control group[(1. 41±0.34) %]. It was concluded that TGF-β2 can induce apoptosis of human trabecular meshwork cells in vitro and may be involved in the decrease of trabecular meshwork cells in the patients with primary open angle glaucoma and aging of normal people.

  9. Insulin-like Growth Factor- I Gene Cloning and Protein Exnression in Bovine Trabecular Meshwork Tissue and Cells

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Whether cultured bovine trabecular meshwork cells and trabecular tissue ex vivo express insulin-like growth factor-I (1GF- I ) messenger RNA (mRNA) and protein was investigated. Total RNA of cultured bovine trabecular meshwork cells as well as trabecular meshwork tissue freshly excised from bovine eyes was extracted, and reverse transcriptase-polymerase chain reaction (RT-PCR)was used to detect IGF-I mRNA. RT-PCR product was verified by sequencing. Immunohistochemical stain was used to detect IGF- I protein. The results showed that a single PCR amplified product was obtained, and the sequence was homologous to the known sequence.. IGF- I immunostain was positive in the cytoplasm of trabecular meshwork cells. It was concluded that trabecular meshwork cells produce IGF- I and contribute to the presence of IGF- I in trabecular meshwork microenvironment as well as aqueous humor. Trabecular meshwork cells were affected by IGF- I not only through paracrine, but also autocrine action. Whether abnormal down-regulations in IGF- I production may contribute to the pathogenesis of primary open-angle glaucoma and the possibility of promoting the autocrine action of IGF- I by trabecular meshwork cells to treat the diesease is worth further investigation.

  10. Transforming Growth Factor-β2 Gene Cloning and Protein Expression in Human Trabecular Meshwork Cells

    Institute of Scientific and Technical Information of China (English)

    曹阳; 魏厚仁; 笪邦红; 李忠玉

    2003-01-01

    Whether cultured human trabecular meshwork cells express transforming growth factor-β2 (TGF-β2) messenger RNA (mRNA) and protein was investigated. Total RNA of 106 cultured human trabecular meshwork cells was extracted with TRIZOL reagent, reverse transcriptase-polymerase chain reaction (RT-PCR) were used for detection of TGF-β2 messenger RNA, and the PCRproduct was verified by sequencing. Immunohistochemical staining was used to detect TGF-β2 protein. The results showed that a single RT-PCR amplified product was obtained, and the sequence was homologous to the known sequence. TGF-β2 immunostaining was positive. It was concluded that trabecular meshwork cells could produce TGF-β2 and contribute to the presence of TGF-β2 in trabecular meshwork microenvironment as well as aqueous humor. Trabecular meshwork cells were affected by TGF-β2 not only through paracrine, but also autocrine action. Whether abnormal changes in TGF-β2 production contribute to the pathogenesis of primary open-angle glaucoma is worth further in vestigation.

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    Lifescience Database Archive (English)

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    Lifescience Database Archive (English)

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  15. Walking through trabecular meshwork biology: Toward engineering design of outflow physiology.

    Science.gov (United States)

    Dautriche, Cula N; Xie, Yubing; Sharfstein, Susan T

    2014-01-01

    According to the World Health Organization, glaucoma remains the second leading cause of blindness in the world. Glaucoma belongs to a group of optic neuropathies that is characterized by chronic degeneration of the optic nerve along with its supporting glia and vasculature. Despite significant advances in the field, there is no available cure for glaucoma. The trabecular meshwork has been implicated as the primary site for regulation of intraocular pressure, the only known modifiable factor in glaucoma development. In this review, we describe the current models for glaucoma studies, primary culture, anterior eye segments, and animal studies and their limitations. These models, especially anterior eye segments and animal tissues, often require careful interpretation given the inter-species variation and are cumbersome and expensive. The lack of an available in vitro 3D model to study trabecular meshwork cells and detailed mechanisms of their regulation of intraocular pressure has limited progress in the field of glaucoma research. In this paper, we review the current status of knowledge of the trabecular meshwork and how the current advances in tissue engineering techniques might be applied in an effort to engineer a synthetic trabecular meshwork as a 3D in vitro model to further advance glaucoma research. In addition, we describe strategies for selection and design of biomaterials for scaffold fabrication as well as extracellular matrix components to mimic and support the trabecular architecture. We also discuss possible uses for a bioengineered trabecular meshwork for both developing a fundamental understanding of trabecular meshwork biology as well as high-throughput screening of glaucoma drugs.

  16. Effect of CD44 Suppression by Antisense Oligonucleotide on Attachment of Human Trabecular Meshwork Cells to HA

    Institute of Scientific and Technical Information of China (English)

    李中国; 张虹

    2004-01-01

    The effects of suppression of CD44 by CD44-specific antisense oligonucleotide on attachment of human trabecular meshwork cells to hyaluronic acid (HA) were observed and the possible relationship between CD44 and primary open-angle glaucoma (POAG) investigated. CD44-specific antisense oligonucleotide was delivered with cationic lipid to cultured human trabecular meshwork cells. The expression of CD44 suppressed by CD44-specific antisense oligonucleotide was detected by RT-PCR and Western blotting. The effect of CD44 suppression by specific antisense oligonucleotide on attachment of trabecular meshwork cells to HA was measured by MTT assay. Results showed that expression of CD44 was suppressed by CD4, specific antisense oligonucleotide. Antisense oligonucleotide also suppressed the adhesion of human trabecular meshwork cells to HA in a concentration dependent manner. It was concluded that attachment of human trabecular meshwork cells to HA was decreased when CD44 was suppressed by specific antisense oligonucleotide. CD44might play a role in pathogenesis of POAG by affecting the adhesion of trabecular meshwork cells to HA.

  17. The trabecular meshwork outflow pathways: structural and functional aspects.

    Science.gov (United States)

    Tamm, Ernst R

    2009-04-01

    The major drainage structures for aqueous humor (AH) are the conventional or trabecular outflow pathways, which are comprised of the trabecular meshwork (made up by the uveal and corneoscleral meshworks), the juxtacanalicular connective tissue (JCT), the endothelial lining of Schlemm's canal (SC), the collecting channels and the aqueous veins. The trabecular meshwork (TM) outflow pathways are critical in providing resistance to AH outflow and in generating intraocular pressure (IOP). Outflow resistance in the TM outflow pathways increases with age and primary open-angle glaucoma. Uveal and corneoscleral meshworks form connective tissue lamellae or beams that are covered by flat TM cells which rest on a basal lamina. TM cells in the JCT are surrounded by fibrillar elements of the extracellular matrix (ECM) to form a loose connective tissue. In contrast to the other parts of the TM, JCT cells and ECM fibrils do not form lamellae, but are arranged more irregularly. SC inner wall endothelial cells form giant vacuoles in response to AH flow, as well as intracellular and paracellular pores. In addition, minipores that are covered with a diaphragm are observed. There is considerable evidence that normal AH outflow resistance resides in the inner wall region of SC, which is formed by the JCT and SC inner wall endothelium. Modulation of TM cell tone by the action of their actomyosin system affects TM outflow resistance. In addition, the architecture of the TM outflow pathways and consequently outflow resistance appear to be modulated by contraction of ciliary muscle and scleral spur cells. The scleral spur contains axons that innervate scleral spur cells or that have the ultrastructural characteristics of mechanosensory nerve endings.

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  6. Inhibition of hyaluronan synthesis reduces versican and fibronectin levels in trabecular meshwork cells.

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    Kate E Keller

    Full Text Available Hyaluronan (HA is a major component of the extracellular matrix (ECM and is synthesized by three HA synthases (HAS. Similarities between the HAS2 knockout mouse and the hdf mutant mouse, which has a mutation in the versican gene, suggest that HA and versican expression may be linked. In this study, the relationship between HA synthesis and levels of versican, fibronectin and several other ECM components in trabecular meshwork cells from the anterior segment of the eye was investigated. HA synthesis was inhibited using 4-methylumbelliferone (4MU, or reduced by RNAi silencing of each individual HAS gene. Quantitative RT-PCR and immunoblotting demonstrated a reduction in mRNA and protein levels of versican and fibronectin. Hyaluronidase treatment also reduced versican and fibronectin levels. These effects could not be reversed by addition of excess glucose or glucosamine or exogenous HA to the culture medium. CD44, tenascin C and fibrillin-1 mRNA levels were reduced by 4MU treatment, but SPARC and CSPG6 mRNA levels were unaffected. Immunostaining of trabecular meshwork tissue after exposure to 4MU showed an altered localization pattern of HA-binding protein, versican and fibronectin. Reduction of versican by RNAi silencing did not affect HA concentration as assessed by ELISA. Together, these data imply that HA concentration affects synthesis of certain ECM components. Since precise regulation of the trabecular meshwork ECM composition and organization is required to maintain the aqueous humor outflow resistance and intraocular pressure homeostasis in the eye, coordinated coupling of HA levels and several of its ECM binding partners should facilitate this process.

  7. Age-Related Changes in Trabecular Meshwork Imaging

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    Mark E. Gold

    2013-01-01

    Full Text Available Purpose. To evaluate the normal aging effects on trabecular meshwork (TM parameters using Fourier domain anterior segment optical coherence tomography (ASOCT images. Patients and Methods. One eye from 45 participants with open angles was imaged. Two independent readers measured TM area, TM length, and area and length of the TM interface shadow from 3 age groups (18–40, 41–60, and 61–80. Measurements were compared using stepwise regression analysis. Results. The average TM parameters were 0.0487 (±0.0092 mm2 for TM area, 0.5502 (±0.1033 mm for TM length, 0.1623 (±0.341 mm2 for TM interface shadow area, and 0.7755 (±0.1574 mm for TM interface shadow length. Interobserver reproducibility coefficients ranged from 0.45 (TM length to 0.82 (TM area. TM area and length were not correlated with age. While the TM interface shadow length did not correlate with age, the TM interface shadow area increased with age. Race, sex, intraocular pressure, and gonioscopy score were not correlated with any TM parameters. Conclusion. Although the TM measurements were not correlated with age, the TM interface shadow area increased with age. Further study is required to determine whether there is any relationship between the age-related ASOCT findings of the TM interface shadow area and physiologic function.

  8. Multiphoton gonioscopy to image the trabecular meshwork of porcine eyes

    Science.gov (United States)

    Masihzadeh, Omid; Ammar, David A.; Kahook, Malik Y.; Gibson, Emily A.; Lei, Tim C.

    2013-03-01

    The aqueous outflow system (AOS), including the trabecular meshwork (TM), the collector channels (CC) and the Schlemm's canal (SC), regulates intraocular pressure (IOP) through the drainage of the aqueous humor (AH). Abnormal IOP elevation leads to increased pressure stress to retinal ganglion cells, resulting in cell loss that can ultimately lead to complete loss of eyesight. Therefore, development of imaging tools to detect abnormal structural and functional changes of the AOS is important in early diagnosis and prevention of glaucoma. Multiphoton microscopy (MPM), including twophoton autofluorescence (TPAF) and second harmonic generation (SHG), is a label-free microscopic technique that allows molecular specific imaging of biological tissues like the TM. Since the TM and other AOS structures are located behind the highly scattering scleral tissue, transscleral imaging of the TM does not provide enough optical resolution. In this work, a gonioscopic lens is used to allow direct optical access of the TM through the cornea for MPM imaging. Compared to transscleral imaging, the acquired MPM images show improved resolution as individual collagen fiber bundles of the TM can be observed. MPM gonioscopy may have the potential to be developed as a future clinical imaging tool for glaucoma diagnostics.

  9. Scanning electron microscopy of the trabecular meshwork: Understanding the pathogenesis of primary angle closure glaucoma

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    Ramanjit Sihota

    2012-01-01

    Full Text Available Purpose: To study ultrastructural changes of the trabecular meshwork in acute and chronic primary angle closure glaucoma (PACG and primary open angle glaucoma (POAG eyes by scanning electron microscopy. Materials and Methods: Twenty-one trabecular meshwork surgical specimens from consecutive glaucomatous eyes after a trabeculectomy and five postmortem corneoscleral specimens were fixed immediately in Karnovsky solution. The tissues were washed in 0.1 M phosphate buffer saline, post-fixed in 1% osmium tetraoxide, dehydrated in acetone series (30-100%, dried and mounted. Results: Normal trabecular tissue showed well-defined, thin, cylindrical uveal trabecular beams with many large spaces, overlying flatter corneoscleral beams and numerous smaller spaces. In acute PACG eyes, the trabecular meshwork showed grossly swollen, irregular trabecular endothelial cells with intercellular and occasional basal separation with few spaces. Numerous activated macrophages, leucocytes and amorphous debris were present. Chronic PACG eyes had a few, thickened posterior uveal trabecular beams visible. A homogenous deposit covered the anterior uveal trabeculae and spaces. Converging, fan-shaped trabecular beam configuration corresponded to gonioscopic areas of peripheral anterior synechiae. In POAG eyes, anterior uveal trabecular beams were thin and strap-like, while those posteriorly were wide, with a homogenous deposit covering and bridging intertrabecular spaces, especially posteriorly. Underlying corneoscleral trabecular layers and spaces were visualized in some areas. Conclusions: In acute PACG a marked edema of the endothelium probably contributes for the acute and marked intraocular pressure (IOP elevation. Chronically raised IOP in chronic PACG and POAG probably results, at least in part, from decreased aqueous outflow secondary to widening and fusion of adjacent trabecular beams, together with the homogenous deposit enmeshing trabecular beams and spaces.

  10. Genomic and post-genomic effects of anti-glaucoma drugs preservatives in trabecular meshwork

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    Izzotti, Alberto, E-mail: izzotti@unige.it [Mutagenesis Unit, IRCCS AOU San Martino – IST, Genova (Italy); Department of Health Sciences, University of Genoa, Via A. Pastore 1, 16132 Genoa (Italy); La Maestra, Sebastiano; Micale, Rosanna Tindara; Longobardi, Maria Grazia [Department of Health Sciences, University of Genoa, Via A. Pastore 1, 16132 Genoa (Italy); Saccà, Sergio Claudio [Ophthalmology Unit, IRCCS AOU San Martino-IST, Genova (Italy)

    2015-02-15

    Highlights: • Glaucoma drug preservatives induce DNA damage in trabecular meshwork cells. • Cellular alteration is related with the occurrence of activation of apoptosis through the intrinsic pathway. • Drug preservatives unable to induce cell damage are ineffective in killing bacteria. • Anti glaucoma drugs should be formulated as single-dose usage devoid of genotoxic preservatives. - Abstract: Oxidative stress plays an important role in glaucoma. Some preservatives of anti-glaucoma drugs, commonly used in glaucoma therapy, can prevent or induce oxidative stress in the trabecular meshwork. The aim of this study is to evaluate cellular and molecular damage induced in trabecular meshwork by preservatives contained in anti-glaucoma drugs. Cell viability (MTT test), DNA fragmentation (Comet test), oxidative DNA damage (8-oxo-dG), and gene expression (cDNA microarray) have been evaluated in trabecular meshwork specimens and in human trabecular meshwork cells treated with benzalkonium chloride, polyQuad, purite, and sofzia-like mixture. Moreover, antimicrobial effectiveness and safety of preservative contents in drugs was tested. In ex vivo experiments, benzalkonium chloride and polyQuad induced high level of DNA damage in trabecular meshwork specimens, while the effect of purite and sofzia were more attenuated. The level of DNA fragmentation induced by benzalkonium chloride was 2.4-fold higher in subjects older than 50 years than in younger subjects. Benzalkonium chloride, and polyQuad significantly increased oxidative DNA damage as compared to sham-treated specimens. Gene expression was altered by benzalkonium chloride, polyQuad, and purite but not by sofzia. In in vitro experiments, benzalkonium chloride and polyQuad dramatically decreased trabecular meshwork cell viability, increased DNA fragmentation, and altered gene expression. A lesser effect was also exerted by purite and sofzia. Genes targeted by these alterations included Fas and effector caspase-3

  11. From DNA damage to functional changes of the trabecular meshwork in aging and glaucoma.

    Science.gov (United States)

    Saccà, Sergio Claudio; Gandolfi, Stefano; Bagnis, Alessandro; Manni, Gianluca; Damonte, Gianluca; Traverso, Carlo Enrico; Izzotti, Alberto

    2016-08-01

    Glaucoma is a degenerative disease of the eye. Both the anterior and posterior segments of the eye are affected, extensive damage being detectable in the trabecular meshwork and the inner retina-central visual pathway complex. Oxidative stress is claimed to be mainly responsible for molecular damage in the anterior chamber. Indeed, oxidation harms the trabecular meshwork, leading eventually to endothelial cell decay, tissue malfunction, subclinical inflammation, changes in the extracellular matrix and cytoskeleton, altered motility, reduced outflow facility and (ultimately) increased IOP. Moreover, free radicals are involved in aging and can be produced in the brain (as well as in the eye) as a result of ischemia, leading to oxidation of the surrounding neurons. Glaucoma-related cell death occurs by means of apoptosis, and apoptosis is triggered by oxidative stress via (a) mitochondrial damage, (b) inflammation, (c) endothelial dysregulation and dysfunction, and (d) hypoxia. The proteomics of the aqueous humor is significantly altered in glaucoma as a result of oxidation-induced trabecular damage. Those proteins whose aqueous humor levels are increased in glaucoma are biomarkers of trabecular meshwork impairment. Their diffusion from the anterior to the posterior segment of the eye may be relevant in the cascade of events triggering apoptosis in the inner retinal layers, including the ganglion cells.

  12. Substratum Stiffness and Latrunculin B Regulate Matrix Gene and Protein Expression in Human Trabecular Meshwork Cells

    Science.gov (United States)

    Thomasy, Sara M.; Wood, Joshua A.; Kass, Philip H.; Murphy, Christopher J.

    2012-01-01

    Purpose. To determine the impact of substratum stiffness and latrunculin-B (Lat-B), on the expression of several matrix proteins that are associated with glaucoma. Methods. Human trabecular meshwork (HTM) cells were cultured on hydrogels possessing stiffness values mimicking those found in normal (5 kPa) and glaucomatous meshworks (75 kPa), or tissue culture polystyrene (TCP; >1 GPa). Cells were treated with 2.0 μM Lat-B in dimethyl sulfoxide (DMSO) or DMSO alone. RT-PCR was used to determine the impact of substratum stiffness and/or Lat-B treatment on the expression of secreted protein, acidic, cysteine rich (SPARC), myocilin, angiopoietin-like factor (ANGPTL)-7, and transglutaminase (TGM)-2. Immunofluorescence was used to assess changes in protein expression. Results. SPARC and myocilin mRNA expression were dramatically increased on the 75 kPa hydrogels and decreased on the 5 kPa hydrogels in comparison to TCP. In contrast, ANGPTL-7 mRNA and TGM-2 mRNA was decreased on the 75 kPa and 5 kPa hydrogels, respectively, in comparison with TCP. Treatment with Lat-B dramatically downregulated both SPARC and myocilin on 75 kPa hydrogels. In contrast, cells grown on TCP produced greater or similar amounts of SPARC and myocilin mRNA after Lat-B treatment. SPARC and myocilin protein expression paralleled changes in mRNA expression. Conclusions. Substratum stiffness impacts HTM matrix gene and protein expression and modulates the impact of Lat-B treatment on the expression of these matrix proteins. Integrating the use of biologically relevant substratum stiffness in the conduction of in vitro experiments gives important insights into HTM cell response to drugs that may more accurately predict responses observed in vivo. PMID:22247475

  13. Molecular Mechanism of Bovine Trabecular Meshwork Cells Apoptosis Induced by Dexamethasone and Protection by Pilocarpine

    Institute of Scientific and Technical Information of China (English)

    Yajuan Gu; Shujun Zeng; Pengxin Qiu; Yuping Wu; Dawei Peng; Guangmei Yan

    2005-01-01

    Purpose: To study the molecular mechanism of trabecular meshwork cells apoptosis induced by dexamethasone and the protection of pilocarpine.Methods: Determining mRNA expression with reverse transcription-polymerase chain reaction (RT-PCR), protein expression with Western blots and the percentage of apoptotic cells with fluorescent microscopy.Results: Dexamethasone up-regulated Fas proteins and affected Bax, caspase-8 and caspase-9 proteins in an action of first decrease then increase. Pre-treatment with pilocarpine decreased the four proteins expression, which were increased by dexamethasone. Pilocarpine self could decrease pro-apoptotic factors Bax, caspase-8 and caspase-9 proteins expression.Conclusion: Fas/FasL pathway participated in apoptotic process induced by dexamethasone in trabecular meshwork cells and the process was probably related with both caspase-8 and caspase-9 pathways. Pilocarpine protected the cells against apoptosis through down-regulating Fas, Bax, caspase-8 and caspase-9 proteins expression.

  14. TGF-β2-induced invadosomes in human trabecular meshwork cells.

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    Hong Han

    Full Text Available Primary open-angle glaucoma (POAG is a leading cause of blindness due to chronic degeneration of retinal ganglion cells and their optic nerve axons. It is associated with disturbed regulation of intraocular pressure, elevated intraocular levels of TGF-β2, aberrant extracellular matrix (ECM deposition and increased outflow resistance in the trabecular meshwork (TM. The mechanisms underlying these changes are not fully understood. Cell-matrix interactions have a decisive role in TM maintenance and it has been suggested that TGF-β-induced inhibition of matrix metalloproteases may drive aberrant ECM deposition in POAG. Invadopodia and podosomes (invadosomes are distinct sites of cell-matrix interaction and localized matrix-metalloprotease (MMP activity. Here, we report on the effects of TGF-β2 on invadosomes in human trabecular meshwork cells. Human TM (HTM cells were derived from donor tissue and pretreated with vehicle or TGF-β2 (2 ng/ml for 3d. Invadosomes were studied in ECM degradation assays, protein expression and MMP-2 activity were assessed by western blot and zymography and ECM protein transcription was detected by RT-qPCR. HTM cells spontaneously formed podosomes and invadopodia as detected by colocalization of Grb2 or Nck1 to sites of gelatinolysis. Pretreatment with TGF-β2 enhanced invadosomal proteolysis and zymographic MMP-2 activity as well as MMP-2, TIMP-2 and PAI-1 levels in HTM cell culture supernatants. Rho-kinase inhibition by H1152 blocked the effects of TGF-β2. Concomitant transcription of fibronectin and collagens-1, -4 and -6 was increased by TGF-β2 and fibrillar fibronectin deposits were observed in areas of invadosomal ECM remodelling. In contrast to a current hypothesis, our data indicate that TGF-β2 induces an active ECM remodelling process in TM cells, characterized by concurrent increases in localized ECM digestion and ECM expression, rather than a mere buildup of material due to a lack of degradation

  15. Synthesis and secretion of transferrin by a bovine trabecular meshwork cell line

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    R. Bertazolli-Filho

    2007-10-01

    Full Text Available The trabecular meshwork (TM is the main outflow pathway in the mammalian eye. Oxidative damage to TM cells has been suggested to be an important cause of impairment of TM functions, leading to deficient drainage of aqueous humor, with deleterious consequences to the eye. Transferrin, a metalloprotein involved in iron transport, has been characterized as an intrinsic eye protein. Since transferrin is implicated in the control of oxidative stress, the objective of the present study was to determine if a bovine TM cell line (CTOB synthesizes and secretes transferrin. The CTOB cell line was cultured in the presence of 35S-methionine and the incubation medium was submitted to immunoprecipitation. Total RNAs from CTOB and isolated bovine TM (freshly isolated, incubated or not were subjected to the reverse transcription-polymerase chain reaction and the amplification products were sequenced. Also, both CTOB and histological TM preparations were processed for transferrin immunolocalization. A labeled peptide of about 80 kDa, the expected size for transferrin, was immunopurified from CTOB samples obtained from the incubation assays. The reverse transcription-polymerase chain reaction and sequencing experiments detected the presence of transferrin mRNA in CTOB and isolated bovine TM. Reactivity to antibodies against transferrin was observed both in CTOB and TM. The results obtained in all of these experiments indicated that the TM is capable of synthesizing and secreting transferrin. The possible implications for the physiology of the eye are discussed.

  16. Endothelial nitric oxide synthase deficiency influences normal cell cycle progression and apoptosis in trabecular meshwork cells

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    Qiong Liao

    2016-06-01

    Full Text Available AIM: To clarify how the endothelial nitric oxide synthase (eNOS, NOS3 make effect on outflow facility through the trabecular meshwork (TM. METHODS: Inhibition of NOS3 gene expression in human TM cells were conducted by three siRNAs. Then the mRNA and protein levels of NOS3 in siRNA-treated and negative control (NC cells were determined, still were the collagen, type IV, alpha 1 (COL4A1 and fibronectin 1 by real-time PCR and Western blot analysis. In addition, NOS3 concentrations in culture supernatant fluids of TM cells were measured. Cell cycle and cell apoptosis analysis were performed using flow cytometry. RESULTS: The mRNA level of NOS3 was decreased by three different siRNA interference, similar results were obtained not only of the relative levels of NOS3 protein, but also the expression levels of COL4A1 and fibronectin 1. The number of cells in S phase was decreased, while contrary result was obtained in G2 phase. The number of apoptotic cells in siRNA-treated groups were significant increased compared to the NC samples. CONCLUSION: Abnormal NOS3 expression can make effects on the proteins levels of extracellular matrix component (e.g. fibronectin 1 and COL4A1. Reduced NOS3 restrains the TM cell cycle progression at the G2/M-phase transition and induced cell apoptosis.

  17. Translimbal laser photocoagulation to the trabecular meshwork as a model of glaucoma in rats.

    Science.gov (United States)

    Levkovitch-Verbin, Hana; Quigley, Harry A; Martin, Keith R G; Valenta, Danielle; Baumrind, Lisa A; Pease, Mary Ellen

    2002-02-01

    To develop and characterize a model of pressure-induced optic neuropathy in rats. Experimental glaucoma was induced unilaterally in 174 Wistar rats, using a diode laser with wavelength of 532 nm aimed at the trabecular meshwork and episcleral veins (combination treatment group) or only at the trabecular meshwork (trabecular group) through the external limbus. Intraocular pressure (IOP) was measured by a tonometer in rats under ketamine-xylazine anesthesia. Possible retinal vascular compromise was evaluated by repeated fundus examinations and by histology. The degree of retinal ganglion cell (RGC) loss was assessed by a masked, semiautomated counting of optic nerve axons. Effects of laser treatment on anterior ocular structures and retina were judged by light microscopy. After the laser treatment, IOP was increased in all eyes to higher than the normal mean IOP of 19.4 +/- 2.1 mm Hg (270 eyes). Peak IOP was 49.0 +/- 6.1 mm Hg (n = 108) in the combination group that was treated by a laser setting of 0.7 seconds and 0.4 W and 34.0 +/- 5.7 mm Hg (n = 46) in the trabecular group. Mean IOP after 6 weeks was 25.5 +/- 2.9 mm Hg in glaucomatous eyes in the combination group compared with 22.0 +/- 1.8 mm Hg in the trabecular group. IOP in the glaucomatous eyes was typically higher than in the control eyes for at least 3 weeks. In the combination group, RGC loss was 16.1% +/- 14.4% at 1 week (n = 8, P = 0.01), 59.7% +/- 25.7% at 6 weeks (n = 88, P < 0.001), and 70.9% +/- 23.6% at 9 weeks (n = 12, P < 0.001). The trabecular group had mean axonal loss of 19.1% +/- 14.0% at 3 weeks (n = 9, P = 0.004) and 24.3% +/- 20.2% at 6 weeks (n = 25, P < 0.001), increasing to 48.4% +/- 32.8% at 9 weeks (n = 12, P < 0.001). Laser treatment led to closure of intertrabecular spaces and the major outflow channel. The retina and choroid were normal by ophthalmoscopy at all times after treatment. Light microscopic examination showed only loss of RGCs and their nerve fibers. Increased IOP caused

  18. Galectin-8 Promotes Cytoskeletal Rearrangement in Trabecular Meshwork Cells through Activation of Rho Signaling

    Science.gov (United States)

    Cao, Zhiyi; Gyawali, Smita; Gong, Haiyan; Soza, Andrea; González, Alfonso; Panjwani, Noorjahan

    2012-01-01

    Purpose The trabecular meshwork (TM) cell-matrix interactions and factors that influence Rho signaling in TM cells are thought to play a pivotal role in the regulation of aqueous outflow. The current study was designed to evaluate the role of a carbohydrate-binding protein, galectin-8 (Gal8), in TM cell adhesion and Rho signaling. Methods Normal human TM cells were assayed for Gal8 expression by immunohistochemistry and Western blot analysis. To assess the role of Gal8 in TM cell adhesion and Rho signaling, the cell adhesion and spreading assays were performed on Gal8-coated culture plates in the presence and the absence of anti-β1 integrin antibody and Rho and Rho-kinase inhibitors. In addition, the effect of Gal8-mediated cell-matrix interactions on TM cell cytoskeleton arrangement and myosin light chain 2 (MLC2) phosphorylation was examined. Principal Findings We demonstrate here that Gal8 is expressed in the TM and a function-blocking anti-β1 integrin antibody inhibits the adhesion and spreading of TM cells to Gal8-coated wells. Cell spreading on Gal8 substratum was associated with the accumulation of phosphorylated myosin light chain and the formation of stress fibers that was inhibited by the Rho inhibitor, C3 transferase, as well as by the Rho-kinase inhibitor, Y27632. Conclusions/Significance The above findings present a novel function for Gal8 in activating Rho signaling in TM cells. This function may allow Gal8 to participate in the regulation of aqueous outflow. PMID:22973445

  19. Up-regulated expression of extracellular matrix remodeling genes in phagocytically challenged trabecular meshwork cells.

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    Kristine M Porter

    Full Text Available BACKGROUND: Cells in the trabecular meshwork (TM, the tissue responsible for draining aqueous humor out of the eye, are known to be highly phagocytic. Phagocytic function in TM cells is thought to play an important role in the normal functioning of the outflow pathway. Dysfunction of phagocytosis could lead to abnormalities of outflow resistance and increased intraocular pressure (IOP. However, the molecular mechanisms triggered by phagocytosis in TM cells are completely unknown. METHODOLOGY/PRINCIPAL FINDINGS: Gene expression profile analysis of human TM cells phagocytically challenged to E. coli or pigment under physiological and oxidative stress environment were performed using Affymetrix U133 plus 2.0 array and analyzed with Genespring GX. Despite the differential biological response elicited by E. coli and pigment particles, a number of genes, including MMP1, MMP3, TNFSF11, DIO2, KYNU, and KCCN2 showed differential expression with both phagocytic ligands in all conditions. Data was confirmed by qPCR in both human and porcine TM cells. Metacore pathway analysis and the usage of recombinant adenovirus encoding the dominant negative mutant of IkB identified NF-κB as a transcription factor mediating the up-regulation of at least MMP1 and MMP3 in TM cells with phagocytosis. In-gel zymography demonstrated increased collagenolytic and caseinolytic activities in the culture media of TM cells challenge to E. coli. In addition, collagenolytic I activity was further confirmed using the self-quenched fluorescent substrate DQ-Collagen I. CONCLUSIONS/SIGNIFICANCE: Here we report for the first time the differential gene expression profile of TM cells phagocytically challenged with either E. coli or pigment. Our data indicate a potential role of phagocytosis in outflow pathway tissue homeostasis through the up-regulation and/or proteolytic activation of extracellular matrix remodeling genes.

  20. Expression of nitric oxide synthase and guanylate cyclase in the human ciliary body and trabecular meshwork

    Institute of Scientific and Technical Information of China (English)

    WU Ren-yi; MA Ning

    2012-01-01

    Background The role played by the nitric oxide (NO) signaling pathway in the aqueous humor dynamics is still unclear.This study was designed to investigate the expression and distribution of NO synthase (NOS) isoforms and guanylate cyclase (GC) in human ciliary body,trabecular meshwork and the Schlemm's canal.Methods Twelve eyes after corneal transplantation were used.Expression of three NOS isoforms (i.e.neuronal NOS (nNOS),inducible NOS (iNOS) and endothelial NOS (eNOS)) and GC were assessed in 10 eyes by immunohistochemical staining using monoclonal or polyclonal antibody of NOS and GC.Ciliary bodies were dissected free and the total proteins were extracted.Western blotting was performed to confirm the protein expression of 3 NOS isoforms and GC.Results Expression of 3 NOS isoforms and GC were observed in the ciliary epithelium,ciliary muscle,trabecular meshwork and the endothelium of the Schlemm's canal.Immunoreactivity of nNOS was detected mainly along the apical cytoplasmic junction of the non-pigmented epithelium (NPE) and pigmented epithelial (PE) cells.Protein expressions of 3 NOS isoforms and GC were confirmed in isolated human ciliary body by Western blotting.Conclusions The expression of NOS isoforms and GC in human ciliary body suggest the possible involvement of NO and cyclic guanosine monophosphate (cyclic GMP,cGMP) signaling pathway in the ciliary body,and may play a role in both processes of aqueous humor formation and drainage.

  1. Experimental erbium: YAG laser photoablation of trabecular meshwork in rabbits: an in-vivo study.

    Science.gov (United States)

    Dietlein, T S; Jacobi, P C; Schröder, R; Krieglstein, G K

    1997-05-01

    Photoablative laser trabecular surgery has been proposed as an outflow-enhancing treatment for open-angle glaucoma. The aim of the study was to investigate the time course of repair response following low-thermal Erbium: YAG laser trabecular ablation. In 20 anaesthetized rabbits gonioscopically controlled ab-interno photoablation of the ligamenta pectinata and underlying trabecular meshwork (TM) was performed with a single-pulsed (200 microseconds) Erbium: YAG (2.94 microns) laser. The right eye received 12-15 single laser pulses (2 mJ) delivered through an articulated zirconium fluoride fiberoptic and a 200 microns (core diameter) quartz fiber tip, the left unoperated eye served as control. At time intervals of 30 minutes, 2, 10, 30, and 60 days after laser treatment, eyes were processed for light- and scanning electron microscopy. The applied energy density of 6-4 J cm-2 resulted in visible dissection of the ligamenta pectinata and reproducible microperforations of the TM exposing scleral tissue accompanied by blood reflux from the aqueous plexus. The initial ablation zones measured 154 +/- 36 microns in depth and 45 +/- 6 microns in width. Collateral thermal damage zones were 22 +/- 8 microns. At two days post-operative, ablation craters were still blood- and fibrin-filled. The inner surface of the craters were covered with granulocytes. No cellular infiltration of the collateral thermal damage zone was observed. At 10 days post-operative, progressive fibroblastic proliferation was observed, resulting in dense scar tissue formation with anterior synechiae, proliferating capillaries and loss of intertrabecular spaces inside the range of former laser treatment at 60 days post-operative. Trabecular microperforations were closed 60 days after laser treatment in all rabbits. IOP in treated and contralateral eyes did not significantly change its level during whole period of observation. Low-thermal infrared laser energy with minimal thermal damage to collateral

  2. Mitochondrial damage in the trabecular meshwork occurs only in primary open-angle glaucoma and in pseudoexfoliative glaucoma.

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    Alberto Izzotti

    Full Text Available BACKGROUND: Open-angle glaucoma appears to be induced by the malfunction of the trabecular meshwork cells due to injury induced by oxidative damage and mitochondrial impairment. Here, we report that, in fact, we have detected mitochondrial damage only in primary open-angle glaucoma and pseudo-exfoliation glaucoma, among several glaucoma types compared. METHODOLOGY/PRINCIPAL FINDINGS: Mitochondrial damage was evaluated by analyzing the common mitochondrial DNA deletion by real-time PCR in trabecular meshwork specimens collected at surgery from glaucomatous patients and controls. Glaucomatous patients included 38 patients affected by various glaucoma types: primary open-angle, pigmented, juvenile, congenital, pseudoexfoliative, acute, neovascular, and chronic closed-angle glaucoma. As control samples, we used 16 specimens collected from glaucoma-free corneal donors. Only primary open-angle glaucoma (3.0-fold and pseudoexfoliative glaucoma (6.3-fold showed significant increases in the amount of mitochondrial DNA deletion. In all other cases, deletion was similar to controls. CONCLUSIONS/SIGNIFICANCE: despite the fact that the trabecular meshwork is the most important tissue in the physiopathology of aqueous humor outflow in all glaucoma types, the present study provides new information regarding basic physiopathology of this tissue: only in primary open-angle and pseudoexfoliative glaucomas oxidative damage arising from mitochondrial failure play a role in the functional decay of trabecular meshwork.

  3. The mouse anterior chamber angle and trabecular meshwork develop without cell death

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    Zabaleta Adriana

    2001-02-01

    Full Text Available Abstract Background The iridocorneal angle forms in the mammalian eye from undifferentiated mesenchyme between the root of the iris and cornea. A major component is the trabecular meshwork, consisting of extracellular matrix organized into a network of beams, covered in trabecular endothelial cells. Between the beams, channels lead to Schlemm's canal for the drainage of aqueous humor from the eye into the blood stream. Abnormal development of the iridocorneal angle that interferes with ocular fluid drainage can lead to glaucoma in humans. Little is known about the precise mechanisms underlying angle development. There are two main hypotheses. The first proposes that morphogenesis involves mainly cell differentiation, matrix deposition and assembly of the originally continuous mesenchymal mass into beams, channels and Schlemm's canal. The second, based primarily on rat studies, proposes that cell death and macrophages play an important role in forming channels and beams. Mice provide a potentially useful model to understand the origin and development of angle structures and how defective development leads to glaucoma. Few studies have assessed the normal structure and development of the mouse angle. We used light and electron microscopy and a cell death assay to define the sequence of events underlying formation of the angle structures in mice. Results The mouse angle structures and developmental sequence are similar to those in humans. Cell death was not detectable during the period of trabecular channel and beam formation. Conclusions These results support morphogenic mechanisms involving organization of cellular and extracellular matrix components without cell death or atrophy.

  4. Integrins in Trabecular Meshwork and Optic Nerve Head: Possible Association with the Pathogenesis of Glaucoma

    Directory of Open Access Journals (Sweden)

    Yisheng Zhong

    2013-01-01

    Full Text Available Integrins are a family of membrane-spanning proteins that are important receptors for cell adhesion to extracellular matrix proteins. They also provide connections between the extracellular environment and intracellular cytoskeletons and are responsible for activation of many intracellular signaling pathways. In vitro and in vivo data strongly indicate that integrin-mediated signaling events can modulate the organization of the actin cytoskeleton in trabecular meshwork (TM cells and are associated with astrocyte migration and microglia activation of the optic nerve head in patients with primary open angle glaucoma. Consequently, increase in resistance in the TM outflow pathways and remodeling of the optic nerve head occur, which in turn increases intraocular pressure (IOP, adds additional mechanical stress and strain to optic nerve axons, and accelerates damage of axons initially caused by optic nerve head remodeling. Integrins appear to be ideal candidates for translating physical stress and strain into cellular responses known to occur in glaucomatous optic neuropathy.

  5. Regulation of trabecular meshwork cell contraction and intraocular pressure by miR-200c.

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    Coralia Luna

    Full Text Available Lowering intraocular pressure (IOP delays or prevents the loss of vision in primary open-angle glaucoma (POAG patients with high IOP and in those with normal tension glaucoma showing progression. Abundant evidence demonstrates that inhibition of contractile machinery of the trabecular meshwork cells is an effective method to lower IOP. However, the mechanisms involved in the regulation of trabecular contraction are not well understood. Although microRNAs have been shown to play important roles in the regulation of multiple cellular functions, little is known about their potential involvement in the regulation of IOP. Here, we showed that miR-200c is a direct postranscriptional inhibitor of genes relevant to the physiologic regulation of TM cell contraction including the validated targets Zinc finger E-box binding homeobox 1 and 2 (ZEB1 and ZEB2, and formin homology 2 domain containing 1 (FHOD1, as well as three novel targets: lysophosphatidic acid receptor 1 (LPAR1/EDG2, endothelin A receptor (ETAR, and RhoA kinase (RHOA. Consistently, transfection of TM cells with miR-200c resulted in strong inhibition of contraction in collagen populated gels as well as decreased cell traction forces exerted by individual TM cells. Finally, delivery of miR-200c to the anterior chamber of living rat eyes resulted in a significant decrease in IOP, while inhibition of miR-200c using an adenoviral vector expressing a molecular sponge led to a significant increase in IOP. These results demonstrate for the first time the ability of a miRNA to regulate trabecular contraction and modulate IOP in vivo, making miR-200c a worthy candidate for exploring ways to alter trabecular contractility with therapeutic purposes in glaucoma.

  6. Glucocorticoids upregulates transepithelial electrical resistance and expression of tight junction-related protein in human trabecular meshwork cells

    Institute of Scientific and Technical Information of China (English)

    ZHUO Ye-hong; HUANG Ya-lin; WEI Yan-tao; LING Yun-lan; LIN Ming-kai; GE Jian

    2005-01-01

    @@ The trabecular meshwork is located at the anterior chamber angle, and is the main route for the outflow of aqueous humor. It is composed of perforated sheets of collagen and elastic tissue covered by trabecular meshwork (TM) cells, forming a filter with decreasing pore size as the canal of Schlemm is approached. TM cells have some endothelial properties, such as the presence of intercellular junctional complexes, particularly tight junctions (TJs). TJs form paracellular seals between adjacent cells and act as fences that segregate protein (and partially lipid) components of the apical and basolateral plasma membrane domains. Under the electron microscope, TJs appear as a series of discrete contacts between the lateral membranes of adjacent cells.

  7. Rho GTPase signaling promotes constitutive expression and release of TGF-β2 by human trabecular meshwork cells.

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    Pervan, Cynthia L; Lautz, Jonathan D; Blitzer, Andrea L; Langert, Kelly A; Stubbs, Evan B

    2016-05-01

    Elevated intraocular pressure (IOP) is causally implicated in the pathophysiology of primary open-angle glaucoma (POAG). The molecular mechanisms responsible for elevated IOP remain elusive, but may involve aberrant expression and signaling of transforming growth factor (TGF)-β2 within the trabecular meshwork (TM). Consistent with previously published studies, we show here that exogenous addition of TGF-β2 to cultured porcine anterior segments significantly attenuates outflow facility in a time-dependent manner. By comparison, perfusing segments with a TGFβRI/ALK-5 antagonist (SB-431542) unexpectedly elicited a significant and sustained increase in outflow facility, implicating a role for TM-localized constitutive expression and release of TGF-β2. Consistent with this thesis, cultured primary or transformed (GTM3) quiescent human TM cells were found to constitutively express and secrete measurable amounts of biologically-active TGF-β2. Disrupting monomeric GTPase post-translational prenylation and activation with lovastatin or GGTI-298 markedly reduced constitutive TGF-β2 expression and release. Specifically, inhibiting the Rho subfamily of GTPases with C3 exoenzyme similarly reduced constitutive expression and secretion of TGF-β2. These findings suggest that Rho GTPase signaling, in part, regulates constitutive expression and release of biologically-active TGF-β2 from human TM cells. Localized constitutive expression and release of TGF-β2 by TM cells may promote or exacerbate elevation of IOP in POAG.

  8. Imaging of trabecular meshwork using Bessel–Gauss light sheet with fluorescence

    Science.gov (United States)

    Jie Jeesmond Hong, Xun; Shinoj, V. K.; Murukeshan, V. M.; Baskaran, M.; Aung, Tin

    2017-03-01

    Ocular imaging technology that holds promise for both fundamental investigation and clinical detection of glaucoma is still a challenging research area. A direct view of the trabecular meshwork (TM) with high resolution is not generally possible because the iridocorneal angle region is obstructed by the sclera overlap. The best approach to observe the aqueous outflow system (AOS) is therefore to view from the opposite angle. In this research work, we developed two imaging systems for the high resolution ex vivo studies of the AOS inside porcine eye, based on a Gaussian illuminated and a digitally scanned Bessel–Gauss beam light sheet fluorescence configurations. The digitally scanned Bessel–Gauss beam is able to overcome the trade-off between the length and thickness of the Gaussian light sheet to give better imaging performance. It has adequate spatial resolution to resolve critical anatomical structures such as the TM, thereby enabling objective information about the AOS. This non-contact and non-invasive imaging methodology with excellent safety profile is expected to be well received by vision researchers and clinicians in the evaluation and management of glaucoma.

  9. Technical Brief: a novel strategy for enrichment of trabecular meshwork protease proteome.

    Science.gov (United States)

    Picciani, Renata; Junk, Anna K; Bhattacharya, Sanjoy K

    2008-05-14

    We present a novel and simple enrichment strategy to capture trabecular meshwork (TM) protease proteome. The method relies on fractionation of TM tissue into cytosolic and nuclear extracts and subsequent affinity enrichment of proteases on peptide inhibitors. A large repertoire of available protease substrate analog peptides enables an improved capture of TM protease proteome compared to SDS-PAGE fractionation alone. Peptide analog inhibitors of protease substrates are immobilized on a protein A or G column using 254 nm intense ultraviolet (UV) light. The TM cytosolic protein extract incubated on the column is eluted with salt or a buffer with a low hydrogen ion concentration. The resultant protein solution is precipitated with acetone, fractionated on SDS-PAGE, in situ trypsin digested, and subjected to mass spectrometry. This relatively simple protocol enables improved capture of cytosolic proteases. We identified 20 previously reported TM proteins from a single donor tissue using affinity enrichment. The majority of identified proteins were either intracellular proteases or known protease inhibitors. Both serine and cysteine proteases were captured using this strategy with improved coverage compared to our previous identification without affinity enrichment.

  10. Targeting the ER-autophagy system in the trabecular meshwork to treat glaucoma.

    Science.gov (United States)

    Stothert, Andrew R; Fontaine, Sarah N; Sabbagh, Jonathan J; Dickey, Chad A

    2016-03-01

    A major drainage network involved in aqueous humor dynamics is the conventional outflow pathway, which is gated by the trabecular meshwork (TM). The TM acts as a molecular sieve, providing resistance to aqueous outflow, which is responsible for regulating intraocular pressure (IOP). If the TM is damaged, aqueous outflow is impaired, IOP increases and glaucoma can manifest. Mutations in the MYOC gene cause hereditary primary open-angle glaucoma (POAG) by promoting the abnormal amyloidosis of the myocilin protein in the endoplasmic reticulum (ER), leading to ER stress-induced TM cell death. Myocilin accumulation is observed in approximately 70-80% of all glaucoma cases suggesting that environmental or other genetic factors may also promote myocilin toxicity. For example, simply preventing myocilin glycosylation is sufficient to promote its abnormal accretion. These myocilin amyloids are unique as there are no other known pathogenic proteins that accumulate within the ER of TM cells and cause toxicity. Moreover, this pathogenic accumulation only kills TM cells, despite expression of this protein in other cell types, suggesting that another modifier exclusive to the TM participates in the proteotoxicity of myocilin. ER autophagy (reticulophagy) is one of the pathways essential for myocilin clearance that can be impacted dramatically by aging and other environmental factors such as nutrition. This review will discuss the link between myocilin and autophagy, evaluating the role of this degradation pathway in glaucoma as well as its potential as a therapeutic target.

  11. Cross-talk between ciliary epithelium and trabecular meshwork cells in-vitro: a new insight into glaucoma.

    Directory of Open Access Journals (Sweden)

    Natalie Lerner

    Full Text Available PURPOSE: It is assumed that the non-pigmented ciliary epithelium plays a role in regulating intraocular pressure via its neuroendocrine activities. To test this hypothesis, we investigated the effect on a human trabecular meshwork (TM cell line (NTM of co-culture with a human non-pigmented ciliary epithelium cell line (ODM-2. METHODS: The cellular cross-talk between ODM-2 and NTM cells was studied in a co-culture system in which the two cell types were co-cultured for 5 to 60 min or 2, 4 and 8h and then removed from the co-culture and analyzed. Analyses of the ERK and p38 mitogen-activated protein kinase (MAPK pathways and of the activity of TM phosphatases and matrix metalloproteins (MMPs were performed. Acid and alkaline phosphatase activity was determined by the DiFMUP (6, 8-difluoro-4-methylumbelliferyl phosphate assay. MMP levels were determined by gelatin zymography. RESULTS: Exposure of NTM cells to ODM-2 cells led to the activation of the MAPK signal transduction pathways in NTM cells within 5 min of co-culture. Phosphorylation of ERK1/ERK2 and p38 peaked at 10 and 15 min and then decreased over time. Interaction between ODM-2 and NTM cells promoted the expression of MMP-9 in the NTM cells after 4h of co-culture. CONCLUSIONS: Our findings provide support for the hypothesis that crosstalk does indeed take place between ODM-2 and NTM cells. Future studies should be designed to determine the relationship between the MMP system, MAPK kinases and phosphatases. Manipulation of these signaling molecules and the related NTM signal transduction pathways may provide targets for developing improved treatments for glaucoma.

  12. Verteporfin without light stimulation inhibits YAP activation in trabecular meshwork cells: Implications for glaucoma treatment.

    Science.gov (United States)

    Chen, Wei-Sheng; Cao, Zhiyi; Krishnan, Chandrasekharan; Panjwani, Noorjahan

    2015-10-16

    Verteporfin, a photosensitizer, is used in photodynamic therapy to treat age-related macular degeneration. In a glaucoma mouse model, Verteporfin without light stimulation has been shown to reduce intraocular pressure (IOP) but the mechanism is unknown. Recent studies have shown that Verteporfin inhibits YAP without light stimulation in cancer cells. Additionally, YAP has emerged as an important molecule in the pathogenesis of glaucoma. We hypothesize that YAP inactivation by Verteporfin in trabecular meshwork (TM) may be related to the reduced IOP observed in vivo. As contractility of TM tissues is associated with IOP, collagen gel contraction assay was used to assess the effect of Verteporfin on contractility of TM cells. Human TM cells were embedded in collagen gel and treated with Verteporfin for 48 h. Areas of collagen gel sizes were quantified by ImageJ. To assess the effect of Verteporfin on the expression of YAP, human TM cells were treated with Verteporfin for 24 h and the expression of YAP was determined by Western blotting. To determine the cytotoxic effect of Verteporfin, human TM cells were treated with Verteporfin for 24 h, and then the cell viability was assessed by WST-1. We demonstrated here that Verteporfin (i) abolishes TM cell-mediated collagen gel contraction in a dose-dependent manner, (ii) attenuates expression of YAP and CTGF (connective tissue growth factor, a direct YAP target gene) in a dose-dependent manner, and (iii) has no significant cytotoxicity below 2 μM. Taken together, Verteporfin may facilitate aqueous humor outflow through the conventional outflow system and reduce IOP by inactivating YAP.

  13. Regulation of myosin light chain phosphorylation in the trabecular meshwork: role in aqueous humour outflow facility.

    Science.gov (United States)

    Rao, P Vasantha; Deng, Peifeng; Sasaki, Yasuharu; Epstein, David L

    2005-02-01

    Cellular contraction and relaxation and integrity of the actin cytoskeleton in trabecular meshwork (TM) tissue have been thought to influence aqueous humour outflow. However, the cellular pathways that regulate these events in TM cells are not well understood. In this study, we investigated physiological agonist-mediated regulation of myosin light chain (MLC) phosphorylation in the TM, and correlated such effects with alterations in aqueous outflow facility, since MLC phosphorylation is a critical biochemical determinant of cellular contraction in TM cells. Treatment of serum starved human TM cells with endothelin-1 (0.1 microM), thromboxane A2 mimetic U-46619 (1.0 microM), or angiotensin II (1 microM), all of which are agonists of G-protein coupled receptors, triggered activation of MLC phosphorylation, as determined by urea/glycerol-based Western blot analysis. Agonist-stimulated increase in MLC phosphorylation was associated with activation of Rho GTPase in TM cells, as determined in pull-down assays. In contrast, treatment of human TM cells with a novel Rho-kinase inhibitor H-1152 (0.1-2 microM), in the presence of serum reduced basal MLC phosphorylation. H-1152 also increased aqueous outflow facility significantly in a dose-dependent fashion, in perfusion studies with cadaver porcine eyes. This effect of H-1152 on outflow facility was associated with decreased MLC phosphorylation in TM tissue of drug-perfused eyes. Collectively, this study identifies potential physiological regulators of MLC phosphorylation in human TM cells and demonstrates the significance of Rho/Rho-kinase pathway-mediated MLC phosphorylation in modulation of aqueous outflow facility through TM.

  14. In Vitro and in Vivo Experimental Studies on Trabecular Meshwork Degeneration Induced by Benzalkonium Chloride (An American Ophthalmological Society Thesis)

    Science.gov (United States)

    Baudouin, Christophe; Denoyer, Alexandre; Desbenoit, Nicolas; Hamm, Gregory; Grise, Alice

    2012-01-01

    Purpose: Long-term antiglaucomatous drug administration may cause irritation, dry eye, allergy, subconjunctival fibrosis, or increased risk of glaucoma surgery failure, potentially due to the preservative benzalkonium chloride (BAK), whose toxic, proinflammatory, and detergent effects have extensively been shown experimentally. We hypothesize that BAK also influences trabecular meshwork (TM) degeneration. Methods: Trabecular specimens were examined using immunohistology and reverse transcriptase–polymerase chain reaction. A trabecular cell line was stimulated by BAK and examined for apoptosis, oxidative stress, fractalkine and SDF-1 expression, and modulation of their receptors. An experimental model was developed with BAK subconjunctival injections to induce TM degeneration. Mass spectrometry (MS) imaging assessed BAK penetration after repeated instillations in rabbit eyes. Results: Trabecular specimens showed extremely low densities of trabecular cells and presence of cells expressing fractalkine and fractalkine receptor and their respective mRNAs. Benzalkonium in vitro induced apoptosis, oxidative stress, and fractalkine expression and inhibited the protective chemokine SDF-1 and Bcl2, also inducing a sustained intraocular pressure (IOP) increase, with dramatic apoptosis of trabecular cells and reduction of aqueous outflow. MS imaging showed that BAK could access the TM at measurable levels after repeated instillations. Conclusion: BAK enhances all characteristics of TM degeneration typical of glaucoma—trabecular apoptosis, oxidative stress, induction of inflammatory chemokines—and causes degeneration in acute experimental conditions, potentially mimicking long-term accumulation. BAK was also shown to access the TM after repeated instillations. These findings support the hypothesis that antiglaucoma medications, through toxicity of their preservative, may cause further long-term trabecular degeneration and therefore enhance outflow resistance, reducing the

  15. Intraocular Pressure and the Mechanisms Involved in Resistance of the Aqueous Humor Flow in the Trabecular Meshwork Outflow Pathways.

    Science.gov (United States)

    Tamm, Ernst R; Braunger, Barbara M; Fuchshofer, Rudolf

    2015-01-01

    Intraocular pressure (IOP), the critical risk factor for glaucoma, is generated and maintained by the aqueous humor circulation system. Aqueous humor is secreted from the epithelial layers of the ciliary body and exits the eye through the trabecular meshwork or the uveoscleral outflow pathways. IOP builds up in response to a resistance to aqueous humor flow in the trabecular outflow pathways. The trabecular outflow resistance is localized in the inner wall region, which comprises the juxtacanalicular connective tissue (JCT) and the inner wall endothelium of Schlemm's canal (SC). Outflow resistance in this region is lowered through the relaxation of contractile myofibroblast-like cells in trabecular meshwork and the adjacent scleral spur, or the contraction of the ciliary muscle. In primary open-angle glaucoma, the most frequent form of glaucoma, outflow resistance of the inner wall region is typically higher than normal. There is evidence that the increase in resistance is related to characteristic biological changes in the resident cells of the JCT, which more and more acquire the structural and functional characteristics of contractile myofibroblasts. The changes involve an augmentation of their actin cytoskeleton and of their surrounding fibrillary extracellular matrix, which connects to JCT cells via integrins. This scenario leads to an overall stiffening of the inner wall region, and is modulated by transforming growth factor-β/connective tissue growth factor signaling. Essentially comparable changes appear to occur in SC endothelial cells. Stiffening of JCT and SC cells is very likely a critical causative factor for the increase in trabecular outflow resistance in POAG.

  16. A Comparison of Gene Expression Profiles between Glucocorticoid Responder and Non-Responder Bovine Trabecular Meshwork Cells Using RNA Sequencing

    Science.gov (United States)

    Bermudez, Jaclyn Y.; Webber, Hannah C.; Brown, Bartley; Braun, Terry A.; Clark, Abbot F.; Mao, Weiming

    2017-01-01

    The most common ocular side effect of glucocorticoid (GC) therapy is GC-induced ocular hypertension (OHT) and GC-induced glaucoma (GIG). GC-induced OHT occurs in about 40% of the general population, while the other 60% are resistant. This study aims to determine the genes and pathways involved in differential GC responsiveness in the trabecular meshwork (TM). Using paired bovine eyes, one eye was perfusion-cultured with 100nM dexamethasone (DEX), while the fellow eye was used to establish a bovine TM (BTM) cell strain. Based on maximum IOP change in the perfused eye, the BTM cell strain was identified as a DEX-responder or non-responder strain. Three responder and three non-responder BTM cell strains were cultured, treated with 0.1% ethanol or 100nM DEX for 7 days. RNA and proteins were extracted for RNA sequencing (RNAseq), qPCR, and Western immunoblotting (WB), respectively. Data were analyzed using the human and bovine genome databases as well as Tophat2 software. Genes were grouped and compared using Student’s t-test. We found that DEX induced fibronectin expression in responder BTM cells but not in non-responder cells using WB. RNAseq showed between 93 and 606 differentially expressed genes in different expression groups between responder and non-responder BTM cells. The data generated by RNAseq were validated using qPCR. Pathway analyses showed 35 pathways associated with differentially expressed genes. These genes and pathways may play important roles in GC-induced OHT and will help us to better understand differential ocular responsiveness to GCs. PMID:28068412

  17. Mapping molecular differences and extracellular matrix gene expression in segmental outflow pathways of the human ocular trabecular meshwork.

    Directory of Open Access Journals (Sweden)

    Janice A Vranka

    Full Text Available Elevated intraocular pressure (IOP is the primary risk factor for glaucoma, and lowering IOP remains the only effective treatment for glaucoma. The trabecular meshwork (TM in the anterior chamber of the eye regulates IOP by generating resistance to aqueous humor outflow. Aqueous humor outflow is segmental, but molecular differences between high and low outflow regions of the TM are poorly understood. In this study, flow regions of the TM were characterized using fluorescent tracers and PCR arrays. Anterior segments from human donor eyes were perfused at physiological pressure in an ex vivo organ culture system. Fluorescently-labeled microspheres of various sizes were perfused into anterior segments to label flow regions. Actively perfused microspheres were segmentally distributed, whereas microspheres soaked passively into anterior segments uniformly labeled the TM and surrounding tissues with no apparent segmentation. Cell-tracker quantum dots (20 nm were localized to the outer uveal and corneoscleral TM, whereas larger, modified microspheres (200 nm localized throughout the TM layers and Schlemm's canal. Distribution of fluorescent tracers demonstrated a variable labeling pattern on both a macro- and micro-scale. Quantitative PCR arrays allowed identification of a variety of extracellular matrix genes differentially expressed in high and low flow regions of the TM. Several collagen genes (COL16A1, COL4A2, COL6A1 and 2 and MMPs (1, 2, 3 were enriched in high, whereas COL15A1, and MMP16 were enriched in low flow regions. Matrix metalloproteinase activity was similar in high and low regions using a quantitative FRET peptide assay, whereas protein levels in tissues showed modest regional differences. These gene and protein differences across regions of the TM provide further evidence for a molecular basis of segmental flow routes within the aqueous outflow pathway. New insight into the molecular mechanisms of segmental aqueous outflow may aid in

  18. OCT Study of Mechanical Properties Associated with Trabecular Meshwork and Collector Channel Motion in Human Eyes

    Science.gov (United States)

    Xin, Chen; Johnstone, Murray; Wang, Ningli; Wang, Ruikang K.

    2016-01-01

    We report the use of a high-resolution optical coherence tomography (OCT) imaging platform to identify and quantify pressure-dependent aqueous outflow system (AOS) tissue relationships and to infer mechanical stiffness through examination of tissue properties in ex vivo human eyes. Five enucleated human eyes are included in this study, with each eye prepared with four equal-sized quadrants, each encompassing 90 degrees of the limbal circumference. In radial limbal segments perfusion pressure within Schlemm’s canal (SC) is controlled by means of a perfusion cannula inserted into the canal lumen, while the other end of the cannula leads to a reservoir at a height that can control the pressure in the cannula. The OCT system images the sample with a spatial resolution of about 5 μm from the trabecular meshwork (TM) surface. Geometric parameters are quantified from the 2D OCT images acquired from the sample subjected to controlled changes in perfusion pressures; parameters include area and height of the lumen of SC, collector channel entrances (CCE) and intrascleral collector channels (ISCC). We show that 3D OCT imaging permits the identification of 3-D relationships of the SC, CCE and ISCC lumen dimensions. Collagen flaps or leaflets are found at CCE that are attached or hinged at only one end, whilst the flaps are connected to the TM by cylindrical structures spanning SC. Increasing static SC pressures resulted in SC lumen enlargement with corresponding enlargement of the CCE and ISCC lumen. Pressure-dependent SC lumen area and height changes are significant at the 0.01 levels for ANOVA, and at the 0.05 for both polynomial curves and Tukey paired comparisons. Dynamic measurements demonstrate a synchronous increase in SC, CCE and ISCC lumen height in response to pressure changes from 0 to 10, 30 or 50 mm Hg, respectively, and the response time is within the 50-millisecond range. From the measured SC volume and corresponding IOP values, we demonstrate that an

  19. Effects of TGF-beta2, BMP-4, and gremlin in the trabecular meshwork: implications for glaucoma.

    Science.gov (United States)

    Wordinger, Robert J; Fleenor, Debra L; Hellberg, Peggy E; Pang, Iok-Hou; Tovar, Tara O; Zode, Gulab S; Fuller, John A; Clark, Abbot F

    2007-03-01

    The primary causative factor of primary open-angle glaucoma (POAG) is elevated intraocular pressure (IOP) due to increased aqueous humor (AH) outflow resistance, which is associated with morphologic and biochemical changes in the trabecular meshwork (TM). Patients with glaucoma have elevated levels of transforming growth factor (TGF)-beta2 in their AH, and TGF-beta has been shown to increase TM extracellular matrix (ECM) production. The bone morphogenetic protein (BMP) signaling pathway modifies TGF-beta signaling in several different tissues, and a prior study demonstrated that TM cells and tissues express members of the BMP gene family. The purpose of this study was to determine whether BMPs can alter TGF-beta2 signaling in the TM and whether there are defects in BMP signaling in glaucoma. ELISA, Western immunoblot analysis, and immunohistochemistry were used to evaluate the expression of BMP proteins in TM cells and tissues. ELISA was used to determine the effects of TGF-beta2 and BMPs on TM fibronectin (FN) secretion. Gene expression was determined by gene microarrays and quantitative (q)PCR. Perfusion-cultured human anterior segments were used to study the effects of altered BMP signaling on IOP. The human TM synthesized and secreted BMP-4 as well as expressed BMP receptor subtypes BMPRI and BMPRII. TM cells responded to exogenous BMP-4 by phosphorylating Smad signaling proteins. Cultured human TM cells treated with TGF-beta2 significantly increased FN levels, and BMP-4 blocked this FN induction. The expression of BMP family genes in normal and glaucomatous TM cells was profiled and significant elevation of mRNA and protein levels of the BMP antagonist gremlin were found in glaucomatous TM cells. In addition, Gremlin was present in human aqueous humor and in the perfusate medium of perfusion-cultured human eyes. Gremlin blocked the negative effect of BMP-4 on TGF-beta-induction of FN. Recombinant Gremlin added to the medium of ex vivo perfusion-cultured human

  20. Non-contact high resolution Bessel beam probe for diagnostic imaging of cornea and trabecular meshwork region in eye

    Science.gov (United States)

    Murukeshan, V. M.; Jesmond, Hong Xun J.; Shinoj, V. K.; Baskaran, M.; Tin, Aung

    2015-07-01

    Primary angle closure glaucoma is a major form of disease that causes blindness in Asia and worldwide. In glaucoma, irregularities in the ocular aqueous outflow system cause an elevation in intraocular pressure (IOP) with subsequent death of retinal ganglion cells, resulting in loss of vision. High resolution visualization of the iridocorneal angle region has great diagnostic value in understanding the disease condition which enables monitoring of surgical interventions that decrease IOP. None of the current diagnostic techniques such as goniophotography, ultrasound biomicroscopy (UBM), anterior segment optical coherence tomography (AS-OCT) and RetCam™ can image with molecular specificity and required spatial resolution that can delineate the trabecular meshwork structures. This paper in this context proposes new concepts and methodology using Bessel beams based illumination and imaging for such diagnostic ocular imaging applications. The salient features using Bessel beams instead of the conventional Gaussian beam, and the optimization challenges in configuring the probe system will be illustrated with porcine eye samples.

  1. Effects of benzalkonium chloride- or polyquad-preserved fixed combination glaucoma medications on human trabecular meshwork cells

    Science.gov (United States)

    Ammar, David A.

    2011-01-01

    Purpose We investigated the potential short and long-term effects in cultured human trabecular meshwork (TM) cells of various topical glaucoma formulations containing different preservatives. Methods We tested the fixed combination medications 0.004% travoprost plus 0.5% timolol preserved with either 0.015% benzalkonium chloride (BAK; DuoTrav®), or with 0.001% polyquad (PQ; DuoTrav® BAK-free); and 0.005% latanoprost plus 0.5% timolol preserved with 0.020% BAK (Xalacom®). Also tested was a range of BAK concentrations (0.001%–0.020%) in balanced salt solution (BSS). Cells were treated for 25 min at 37 °C with solutions diluted 1:10 and 1:100 to mimic the reduced penetration of topical preparations to the anterior chamber. The percentage of live cells was determined immediately after treatment through the uptake of the fluorescent vital dye calcein-AM. To determine any long-term effects, we assayed release of matrix metalloproteinase 9 (MMP-9) and apoptosis 24 h after treatments. Results BAK demonstrated a dose-dependent reduction in TM cell viability, ranging from 71±5% live cells at 0.001% BAK (diluted 1:10) to 33±3% live cells at 0.020% BAK (diluted 1:10). Travoprost (0.004%) plus 0.5% timolol preserved with 0.015% BAK had statistically fewer live TM cells (79±7%) than the same preparation preserved with 0.001% polyquad® (PQ; 93±1%; p<0.001). Latanoprost plus timolol preserved with 0.020% BAK (29±9% live cells) was similar to the 0.020% BAK (33±3%) treatment. However, travoprost plus timolol preserved in 0.015% BAK had significantly more live cells (83±12%) than the 1:10 dilution of 0.015% BAK (49±10%). We also found 0.020% BAK (diluted 1:100) resulted in elevated levels of extracellular MMP-9 at 24 h. Conclusions These results demonstrate that the substitution of the preservative BAK from topical ophthalmic drugs results in greater in vitro viability of TM cells. Travoprost with timolol, but not latanoprost with timolol, countered some of the toxic

  2. Prostaglandin EP2 receptor signaling protects human trabecular meshwork cells from apoptosis induced by ER stress through down-regulation of p53

    OpenAIRE

    Kalouche, Georges; Boucher, Céline; Coste, Annick; Debussche, Laurent; Orsini, Cécile; Baudouin, Christophe; Debeir, Thomas; Vigé, Xavier; Rostène, William

    2016-01-01

    International audience; E-prostanoid receptor subtype 2 (EP2) agonists are currently under clinical development as hypotensive agents for the treatment of ocular hypertension. However, the effects of EP2 receptor agonists on trabecular meshwork (TM) alterations leading to primary open-angle glaucoma (POAG) are still unknown. Here, we evaluated whether EP2 receptor activation exhibits protective functions on TM cell death induced by endoplasmic reticulum (ER) stress. We show that the EP2 recep...

  3. Cathepsin B is up-regulated and mediates extracellular matrix degradation in trabecular meshwork cells following phagocytic challenge.

    Directory of Open Access Journals (Sweden)

    Kristine Porter

    Full Text Available Cells in the trabecular meshwork (TM, a tissue responsible for draining aqueous humor out of the eye, are known to be highly phagocytic. Phagocytic activity in TM cells is thought to play an important role in outflow pathway physiology. However, the molecular mechanisms triggered by phagocytosis in TM cells are unknown. Here we investigated the effects of chronic phagocytic stress on lysosomal function using different phagocytic ligands (E. coli, carboxylated beads, collagen I-coated beads, and pigment. Lysotracker red co-localization and electron micrographs showed the maturation of E. coli- and collagen I-coated beads-containing phagosomes into phagolysosomes. Maturation of phagosomes into phagolysosomes was not observed with carboxylated beads or pigment particles. In addition, phagocytosis of E. coli and collagen I-coated beads led to increased lysosomal mass, and the specific up-regulation and activity of cathepsin B (CTSB. Higher levels of membrane-bound and secreted CTSB were also detected. Moreover, in vivo zymography showed the intralysosomal degradation of ECM components associated with active CTSB, as well as an overall increased gelatinolytic activity in phagocytically challenged TM cells. This increased gelatinolytic activity with phagocytosis was partially blocked with an intracellular CTSB inhibitor. Altogether, these results suggest a potential role of phagocytosis in outflow pathway tissue homeostasis through the up-regulation and/or proteolytic activation of extracellular matrix remodeling genes.

  4. Myocilin蛋白在小梁网组织中的作用%Function of Myocilin in Trabecular Meshwork

    Institute of Scientific and Technical Information of China (English)

    贺琴

    2011-01-01

    Myocilin基因是与原发性开角型青光眼成因有关的基因.其蛋白产物myocilin蛋白是一种分泌型糖蛋白,具有特征性区域:N端亮氨酸拉链区,中央链接区,C端类嗅质蛋白(嗅素)区.眼组织中,小梁网myocilin蛋白表达水平最高且在细胞内外均可检测到.细胞内myocilin蛋白由小梁网细胞以外泌体样囊泡形式释放至胞外,突变时分泌受阻并异常聚集,使细胞致敏诱发凋亡.细胞外myocilin蛋白通过与一种或多种细胞外基质蛋白相互作用影响细胞的形态、粘接、迁移活动,调节细胞外基质的成分和结构,从而影响房水流出系统.%Myocilin gene is associated with primary open -angle glaucoma (POAG) . The product of myocilin is a secreted glycoprotein. Characteristic structural motifs include a leucine zipper region, a central linker region and an olfactomedin domain. In the eye, myocilin is expressed highest in the trabecular meshwork ( TM) . Both intracellular and extracellular expression can be detected. Myocilin is released from TM cells to extracellular region with exosomes. Mutations of myocilin are secretion-incompetent and aggregate in the cells, subsequently inducing endoplasmic reticulum response, damaging the structure and function of mitochondria, and sensitizing cells to apoptosis. Extracellular myocilin present in the matrix affects adhesion, morphology, and migratory of human TM cells. Myocilin can regulate the composition and structure of the extracellular matrix, play an extracellular function and impact the normal aqueous outflow. This article reviews gene and protein of myocilin and their relationship with TM.

  5. Progenitors for the Corneal Endothelium and Trabecular Meshwork: A Potential Source for Personalized Stem Cell Therapy in Corneal Endothelial Diseases and Glaucoma

    Directory of Open Access Journals (Sweden)

    Wing Yan Yu

    2011-01-01

    Full Text Available Several adult stem cell types have been found in different parts of the eye, including the corneal epithelium, conjunctiva, and retina. In addition to these, there have been accumulating evidence that some stem-like cells reside in the transition area between the peripheral corneal endothelium (CE and the anterior nonfiltering portion of the trabecular meshwork (TM, which is known as the Schwalbe's Ring region. These stem/progenitor cells may supply new cells for the CE and TM. In fact, the CE and TM share certain similarities in terms of their embryonic origin and proliferative capacity in vivo. In this paper, we discuss the putative stem cell source which has the potential for replacement of lost and nonfunctional cells in CE diseases and glaucoma. The future development of personalized stem cell therapies for the CE and TM may reduce the requirement of corneal grafts and surgical treatments in glaucoma.

  6. Effects of Nitric Oxide on Proliferation and Apoptosis of Cultured Bovine Trabecul ar Meshwork Cells

    Institute of Scientific and Technical Information of China (English)

    薛蔚; 杜蜀华; 李勇; 杨业金; 孙京华

    2002-01-01

    The effects of different doses of nitric oxide (NO) on the proliferation and apoptosis of the cultured bovine trabecular meshwork (TM) cells were studied. L-arginine and NG-nitro-L-arginine methyl (L-NAME) were incubated with TM cells for 48 h. In the control group, no medicine was given. In the experimental groups, concentrations of L-arginine and L-NAME were 1 × 10- 7 mol/L,1 × 10-6 mol/L, 1 × 10-5 mol/L, 1 × 10-4 mol/L, 1 × 10-3 mol/L and 1 × 10-2 mol/L, respectively.NO2- in supernate, the proliferation and apoptosis of TM cells and mRNA expression of bcl-2 and bax were measured by Griess reagent, terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL), MTT assay and in situ hybridization,respectively. The results showed that Larginine with concentration ≥1 × 10-4 mol/L could induce apoptosis of the TM cells and inhibit the proliferation of TM cells through increasing the NO levels, down-regulating bcl-2 mRNA expression and up-regulating bax mRNA expression; L-NAME with concentration ≥1 × 10-5 mol/L could induce the proliferation of the TM cells through suppressing the production of NO. It was concluded that NO in high level could induce apoptosis of the TM cells and suppress the proliferation of the TM cells.

  7. σ-1 receptor stimulation protects against pressure-induced damage through InsR-MAPK signaling in human trabecular meshwork cells

    Science.gov (United States)

    Meng, Bo; Li, Hongyi; Sun, Xian; Qu, Wei; Yang, Binbin; Cheng, Fang; Shi, Liping; Yuan, Huiping

    2017-01-01

    The purpose of the present study was to investigate the protective effect of the σ-1 receptor (Sig-1R) agonist (+)-pentazocin (PTZ) on pressure-induced apoptosis and death of human trabecular meshwork cells (hTMCs). The expression levels of Sig-1R and insulin receptor (InsR) were examined in hTMCs. Cells were cultured under a pressure of 0, 20, 40, 60 and 80 mmHg for 48 h, and under 80 mmHg for 44 h, after which the cells were treated with (+)-PTZ (20 µM), N-(2-(3,4-dichlorophenyl)ethyl)-N-methyl-2-(dimethylamino) ethylamine (BD-1063; 20 µM) administered 30 min prior to (+)-PTZ, or BD-1063 (20 µM) and then exposed to 80 mmHg again until the 48 h time-point. The changes of the cells were observed by optical and electron microscopy, the apoptosis and death of hTMCs were detected by ethidium bromide/acridine orange dual staining assay and the expression of Sig-1R and InsR by reverse transcription-quantitative polymerase chain reaction and western blot analysis. The phosphorylation of extracellular signal-regulated kinase (ERK), an important downstream protein of the InsR-mitogen-activated protein kinases (MAPK) signaling pathway, was also detected by western blot analysis when (+)-PTZ and BD-1063 were added to the 80 mmHg-treated cells. Sig-1Rs and InsRs were expressed in hTMCs. The apoptosis and death of hTMCs increased from 40 mmHg with 50% cell death when the pressure was at 80 mmHg and the structure of the cells noticeably changed. The expression of Sig-1R and InsR increased along with the elevation of pressure. (+)-PTZ decreased the apoptosis and death of hTMCs and increased the expression of Sig-1R and InsR, and the phosphorylation of ERK. Such effects were blocked by BD-1063. The present study suggested that Sig-1R agonist (+)-PTZ can protect hTMCs from pressure-induced apoptosis and death by activating InsR and the MAPK signal pathway. PMID:28560459

  8. Preventive effects of omega-3 and omega-6 Fatty acids on peroxide mediated oxidative stress responses in primary human trabecular meshwork cells.

    Directory of Open Access Journals (Sweden)

    Theofilos Tourtas

    Full Text Available Pathologic processes in glaucoma include increased apoptosis, accumulation of extracellular material in the trabecular meshwork and optic nerve, condensations of the cytoskeleton and precocious cellular senescence. Oxidative stress was shown to generate these alterations in primary ocular cells. Fatty acids omega-3 and -6 are alleged to constitute a prophylaxis against these deleterious effects. Here, we tested actual preventive effects omega-3 and -6 against peroxide induced stress responses in primary human trabecular meshwork cells. Changes of mitochondrial activity, proliferation, heat shock proteins, extracellular matrix components, and inflammatory markers were evaluated. Alterations of the cytoskeleton were evaluated by phalloidin labeling. Here we report a repressive effect of omega-6 on metabolic activity and proliferation, which was not detected for omega-3. Both agents were able to prevent the anti-proliferative effect of H₂O₂, but only omega-3 prevented metabolic repression. Expression of heat shock protein 27 was unaltered by both fatty acids, whereas heat shock protein 90 was significantly induced by both. Omega-6 increased fibronectin and connective tissue growth factor synthesis, as well as the amount of secreted fibronectin. Omega-3, instead, induced plasminogen activator inhibitor 1 synthesis. H₂O₂ further increased fibronectin production in omega-6 supplemented cells, which was not the case in omega-3 treated cells. H₂O₂ stimulation of plasminogen activator inhibitor 1 and connective tissue growth factor was repressed by both fatty acids. Both fatty acids appeared to abolish H₂O₂ mediated stimulation of nuclear factor κB and IL-6, but not IL-1α and IL-8. H₂O₂ induced formation of cross-linked actin networks and stress fibers, which was reduced by preemptive application of omega-3. Omega-6, in contrast, had no protective effect on that, and even seemed to promote condensation. Based on the observed side

  9. Functional pharmacological evidence for EP2 and EP4 prostanoid receptors in immortalized human trabecular meshwork and non-pigmented ciliary epithelial cells.

    Science.gov (United States)

    Crider, J Y; Sharif, N A

    2001-02-01

    The aim of these studies was to characterize the molecular pharmacology of the prostanoid receptors positively coupled to stimulation of adenylyl cyclase activity in immortalized human trabecular meshwork (TM-3) cells and to compare these results with that of the receptors in immortalized human nonpigmented epithelial (NPE) cells. In general, the TM-3 and NPE cells showed a similar profile with respect to their responses to various prostaglandin (PG) receptor agonists. The rank order of potency (EC50; means +/- SEM) for these compounds in the TM-3 cells was: PGE2 (124 +/- 21 nM) > 13,14-dihydro-PGE1 (430 +/- 110 nM) = PGE1 (522 +/- 345 nM) > 11-deoxy-PGE1 (1063 +/- 118 nM) = 16,16-dimethyl-PGE2 (1776 +/- 460 nM) = butaprost (1920 +/- 527 nM) > PGD2 = PGI2 = PGF2alpha (n = 3 - 12). While the agonist profile indicated the presence of EP2 receptors, the effects of the EP4 receptor antagonists suggested the additional expression of EP4 receptors in both of these cells. Thus, the EP4 receptor antagonist, AH23848B, at a concentration of 30 microM, caused a dextral shift in the PGE2 concentration-response curves in both TM-3 and NPE cells coupled with a 20-28% decrease in the maximal response of PGE2, indicating apparent noncompetitive antagonism profiles. The antagonist potency of AH23848B in these cells was: Kb = 38.4 +/- 14.8 microM and 23.5 +/- 4.5 microM; -log Kb = 4.7. The other EP4 receptor antagonist, AH22921 (-log Kb = 4.1 - 4.7), was weaker than AH23848B. Taken together, these pharmacological studies have shown than TM-3 and NPE cells apparently contain functional EP2 and EP4 prostanoid receptors positively coupled to adenylyl cyclase.

  10. Effects of Visible Light on Cultured Bovine Trabecular Cells

    Institute of Scientific and Technical Information of China (English)

    姜发纲; 郝风芹; 魏厚仁; 许德胜

    2004-01-01

    To explore the biological effects of light on trabecular cells, cultured bovine trabecular cells were exposed to visible light of different wavelength with different energy. Cellular morphology, structure, proliferation, and phagocytosis were observed. The cells showed no remarkable changes when the energy was low. When the exposure energy reached 1. 12 mW/cm2 , the cytoplasm showed a rough appearance, and cell proliferation and phagocytosis decreased. This phototoxicity was strong with white light (compound chromatic light), moderate with violet light or yellow light, and mild with red light.

  11. Electric Impedance Spectroscopy for On-Chip Analysis of Human Trabecular Meshwork Endothelium%阻抗谱芯片用于人眼小梁网细胞分析

    Institute of Scientific and Technical Information of China (English)

    顾雯雯; 赵毅

    2013-01-01

    The in vitro cultured human trabecular meshwork (TM) was investigated using electric impedance spectroscopy (EIS) in real time.TM is a critical determinant of intraocular pressure (IOP),the increase of which is the main cause of glaucoma.An array of interdigitated microelectrodes (IMEs) was fabricated for electric impedance sensing.An equivalent electric circuit model was proposed to study the cellular activities on the IMEs,showing that the impedance of extracellular matrix (ECM) and the cell coverage ratio have distinct signatures on the spectrum.The utility of the EIS was demonstrated by treating TM cells during their proliferation with dexamethasone (DEX).The impedance measurement at 40 kHz showed that a higher DEX concentration can induce more severe inhibition of cell proliferation.The measurement was validated by AlamarBlue assay.The measurement provided a reasonable explanation on glucocorticoid induced glaucoma,where the glucocorticoid alters the metabolic and physiological functions of TM cells by inhibiting normal cell growth and proliferation.%采用阻抗谱分析法对体外培养人眼小梁网细胞进行实时在线检测.人眼眼压过高将导致青光眼病变,而小梁网对于眼压高低至关重要.制备了叉指式阵列微电极作为阻抗传感器敏感单元.提出了分析小梁网细胞生物行为特征的等效电路模型,通过仿真分析表明该电路模型可在不同频段区分人眼小梁网细胞外基质和细胞繁殖率等阻抗参数值.采用叉指式阻抗谱芯片对经地塞米松药物处理的小梁网细胞进行了实时在线监测,结果表明40 kHz时高浓度地塞米松对小梁网细胞增殖具有较大的抑制作用,该结论与AlamarBlue试剂法得到的结论一致.阻抗测试结果为糖皮质激素诱导的青光眼提供了一种合理的解释,认为该病变与正常细胞增殖率异常有关.

  12. The effect of endothelin-1 on the phagocytic function of human trabecular meshwork cells in vitro%内皮素-1对人小梁细胞吞噬功能的影响

    Institute of Scientific and Technical Information of China (English)

    向艳; 李贵刚; 徐林娟; 陈志祺; 王瑞林; 张虹

    2010-01-01

    accumulating evidence for a role of ET-1 in the pathogenesis of glaucoma.However,the effect of ET-1 on the phagocytic function in trabecular meshwork cells (TMCs) is unclear.ObjectiveThis study is to observe the effect of ET-1 on the phagocytic function in cultured human TMCs.Methods Human trabecular meshwork tissue was obtained from healthy donator and cultured and subcultured in vitro by the explant culture method.The third passage of human TMCs were incubated with fluoresent red-labeled latex beads for 0,4,8,12,24,48 and 72 hours.The phagocytic kinetics of human TMCs were continuously evaluated by counting the number of latex beads in TMCs using a fluorescence microscope.Depending on the concentrations of ET-1 in culture medium,the TMCs were divided into control group (without ET-1),low-dose ET-1 (10~(-9)mol/L) treatment group,middle-dose ET-1 (10~(-8)mol/L) treatment group and high-dose ET-1 (10~(-7) mol/L) treatment group.In addition,based on the addition of endothelin receptor (ETAR) antagonist,the TMCs were divided into control group (without ETAR antagonist),ET-1 (10~(-8)mol/L) treatment group,ETAR antagonist (1×10~(-7)mol/L BQ123+10~(-8)mol/L ET-1) treatment group and ETBR antagonist(1×10~(-7) mol/L BQ788+10~(-8) mol/L ET-1)treatment group.TMCs of each group were incubated with latex beads,and the numbers of latex beads in TMCs were counted under a fluorescent microscope.Results Cultured HTM cells showed positive reactions for FN,LN,NSE and negative response for FⅧRag.The phagocytic kinetics test revealed that the latex beads were detected 4 hours after incubation.The density of latex beads was gradually increased with the delay of incubation duration and peaked at 24 hours.The number of the latex beads saturated after 48 hours of incubation.However,the number of latex beads in TMCs was significantly reduced after the addition of ET-1 in a dose-dependent manner (F=28.91,P<0.05).The number of latex beads in the ET-1 group was less than that in the control group

  13. Effect of soluble CD44 molecule on the expression of apoptosis regulatory protein bcl-2 associated death factor bad in human trabecular meshwork cell%可溶性CD44分子对人眼小梁网细胞凋亡调节蛋白bcl-2相关死亡因子bad表达的影响

    Institute of Scientific and Technical Information of China (English)

    梁宗宝; 吴瑜瑜; 郭茂生

    2012-01-01

    亡因子bad蛋白的表达.%Background Researches demonstrated that the levels of soluble CD44 (sCD44)molecule in aqueous is significantly higher in primary open-angle glaucomous(POAG) eye than normal eye,but how the sCD44 would affect the expression of apoptosis protein in trabecular meshwork cells is below understanding. Objective The present study was to investigate the effect of sCD44 on the expression of regulatory proteins bcl-2 associated death factor bad in trabecular meshwork cells in the patients with POAG. Methods Human scleral tissue with trabecular meshwork were obtained from POAG patients during the surgery.The trabecular meshwork cells were primarily cultured by explant culture method and identified by immunochemistry.The third generation of cells were incubated with free-serum DMEM/F12 medium added differnt dosages of sCD44 (0,1,5,10,25,50 mg/L) for 48 hours.The expression of bad protein in cultured cells was detected using cell counting kit-8 (CCK-8) as the absorbance values at 490 nm(A,90 value),and the bad protein level in cultured cells was assayed by ELISA. Results The cultured cells showed the positive response for laminin ( LM ),neuron specific enolase ( NSE ),fibronectin ( FN ) monoclonal antibodies.The CCK-8 assay showed that the A490 values of the trabecular meshwork cells in 0,1,5,10,25,50 μg/L of sCD44 groups were 0.2460±0.0019,0.1874±0.0015,0.1570±0.0016,0.1302±0.0019,0.1084±0.0018,0.0940±0.0020 respectively with a statistically significant difference among the 6 groups( F =14.922,P =0.000 ),and the A490 values in various dosages of sCD44 groups were significantly lower than the 0 μg/L sCD44 group (P=0.013,0.008,0.011,0.005,0.004).The ELISA assay showed that bad protein levels in 0,1,5,10,25,50 μg/L of sCD44 groups were ( 114.8461 ± 2.9560 ),( 137.8270 ± 2.4259 ),( 161.4194 ± 3.7381 ),( 170.9453 ± 3.2006 ),( 221.2252 ±4.3738 ),( 324.6167±4.4220) ng/L,showing a total difference among them ( F =16.610,P =0.000 ),and the bad protein levels in various dosages of sCD44

  14. Networks and meshworks in strategizing

    DEFF Research Database (Denmark)

    Esbjerg, Lars; Andersen, Poul Houman

    the literature on networks and network pictures, and identifies several shortcomings of this work. To develop the notion of business meshworks as an alternative for understanding strategizing practices in business interaction, the paper draws on recent writings within anthropology and the strategy...

  15. An Elastic Model of Blebbing in Nuclear Lamin Meshworks

    Science.gov (United States)

    Funkhouser, Chloe; Sknepnek, Rastko; Shimi, Takeshi; Goldman, Anne; Goldman, Robert; Olvera de La Cruz, Monica

    2013-03-01

    A two-component continuum elastic model is introduced to analyze a nuclear lamin meshwork, a structural element of the lamina of the nuclear envelope. The main component of the lamina is a meshwork of lamin protein filaments providing mechanical support to the nucleus and also playing a role in gene expression. Abnormalities in nuclear shape are associated with a variety of pathologies, including some forms of cancer and Hutchinson-Gilford progeria syndrome, and are often characterized by protruding structures termed nuclear blebs. Nuclear blebs are rich in A-type lamins and may be related to pathological gene expression. We apply the two-dimensional elastic shell model to determine which characteristics of the meshwork could be responsible for blebbing, including heterogeneities in the meshwork thickness and mesh size. We find that if one component of the lamin meshwork, rich in A-type lamins, has a tendency to form a larger mesh size than that rich in B-type lamins, this is sufficient to cause segregation of the lamin components and also to form blebs rich in A-type lamins. The model produces structures with comparable morphologies and mesh size distributions as the lamin meshworks of real, pathological nuclei. Funded by US DoE Award DEFG02-08ER46539 and by the DDR&E and AFOSR under Award FA9550-10-1-0167; simulations performed on NU Quest cluster

  16. Recent origin of low trabecular bone density in modern humans.

    Science.gov (United States)

    Chirchir, Habiba; Kivell, Tracy L; Ruff, Christopher B; Hublin, Jean-Jacques; Carlson, Kristian J; Zipfel, Bernhard; Richmond, Brian G

    2015-01-13

    Humans are unique, compared with our closest living relatives (chimpanzees) and early fossil hominins, in having an enlarged body size and lower limb joint surfaces in combination with a relatively gracile skeleton (i.e., lower bone mass for our body size). Some analyses have observed that in at least a few anatomical regions modern humans today appear to have relatively low trabecular density, but little is known about how that density varies throughout the human skeleton and across species or how and when the present trabecular patterns emerged over the course of human evolution. Here, we test the hypotheses that (i) recent modern humans have low trabecular density throughout the upper and lower limbs compared with other primate taxa and (ii) the reduction in trabecular density first occurred in early Homo erectus, consistent with the shift toward a modern human locomotor anatomy, or more recently in concert with diaphyseal gracilization in Holocene humans. We used peripheral quantitative CT and microtomography to measure trabecular bone of limb epiphyses (long bone articular ends) in modern humans and chimpanzees and in fossil hominins attributed to Australopithecus africanus, Paranthropus robustus/early Homo from Swartkrans, Homo neanderthalensis, and early Homo sapiens. Results show that only recent modern humans have low trabecular density throughout the limb joints. Extinct hominins, including pre-Holocene Homo sapiens, retain the high levels seen in nonhuman primates. Thus, the low trabecular density of the recent modern human skeleton evolved late in our evolutionary history, potentially resulting from increased sedentism and reliance on technological and cultural innovations.

  17. Rate of change in central corneal thickness: a viability indicator for conventional drainage tissues in organ culture.

    Science.gov (United States)

    Wan, Z; Brigatti, L; Ranger-Moore, J; Ethier, C R; Stamer, W D

    2006-06-01

    Organ culture of human anterior segments is a powerful tool for understanding trabecular meshwork biology. However, data from a significant percentage of cultured anterior segments are unusable because tissues fail to meet quality control requirements, such as having adequate trabecular meshwork histology. The purpose of the present study was to evaluate a novel, real time method for assessing the viability of conventional drainage tissues in the human anterior segment perfusion model. Twenty-two human anterior segments were perfusion cultured using standard techniques for one week while measuring outflow facility and central corneal thickness (CCT). After perfusion-fixation, toludine blue-stained histological sections of drainage tissues from all four quadrants of each anterior segment were graded and endothelial cell nuclei from cornea centers were stained with 4',6-diamidino-2-phenylindole and counted. We found that most anterior segments with a stable outflow facility had a CCT that decreased over time, while anterior segments with an unstable outflow facility had CCT measurements that failed to decrease over time (P<0.01). When comparing CCT measurements to histological appearance of outflow tissues, we found that in 11/11 cases, anterior segments with an acceptable histological score had a negative CCT slope (P<0.01). Conversely in 3/4 instances, anterior segments with an unacceptable histological score had a positive CCT slope. Lastly, we observed a significant relationship between CCT measurements and corneal endothelial density (P<0.01). Thus, the simple procedure of measuring CCT during anterior segment perfusion provides a second useful measure to assess the viability of the anterior segment during the perfusion process.

  18. [Retinal and trabecular degeneration in glaucoma: new insights into pathogenesis and treatment].

    Science.gov (United States)

    Denoyer, A; Roubeix, C; Sapienza, A; Réaux-Le Goazigo, A; Mélik-Parsadaniantz, S; Baudouin, C

    2015-04-01

    Academic and industrial research has brought new insights into the pathogenesis of glaucoma, aiming at identifying and targeting specific mechanisms to improve our current therapeutic strategy. Retinal neurodegeneration is still the main focus, whether in terms of extrinsic factors such as neurotrophin deprivation, glutamate toxicity, vascular deficiency and neuro-inflammation from glial cells, or in terms of retinal ganglion cell intrinsic sensibility to proapoptotic signals. However, glaucoma is not solely a retinal disease but also involves retinal and trabecular meshwork degeneration, extending into and/or even originating from the brain. The present review summarizes our current knowledge of key mechanisms involved in glaucoma degeneration, focusing on the direction of current research towards the future of glaucoma therapy.

  19. Trabecular bone structure in the primate wrist.

    Science.gov (United States)

    Schilling, Ann-Marie; Tofanelli, Sergio; Hublin, Jean-Jacques; Kivell, Tracy L

    2014-05-01

    Trabecular (or cancellous) bone has been shown to respond to mechanical loading throughout ontogeny and thus can provide unique insight into skeletal function and locomotion in comparative studies of living and fossil mammalian morphology. Trabecular bone of the hand may be particularly functionally informative because the hand has more direct contact with the substrate compared with the remainder of the forelimb during locomotion in quadrupedal mammals. This study investigates the trabecular structure within the wrist across a sample of haplorhine primates that vary in locomotor behaviour (and thus hand use) and body size. High-resolution microtomographic scans were collected of the lunate, scaphoid, and capitate in 41 individuals and eight genera (Homo, Gorilla, Pan, Papio, Pongo, Symphalangus, Hylobates, and Ateles). We predicted that particular trabecular parameters would 1) vary across suspensory, quadrupedal, and bipedal primates based on differences in hand use and load, and 2) scale with carpal size following similar allometric patterns found previously in other skeletal elements across a larger sample of mammals and primates. Analyses of variance (trabecular parameters analysed separately) and principal component analyses (trabecular parameters analysed together) revealed no clear functional signal in the trabecular structure of any of the three wrist bones. Instead, there was a large degree of variation within suspensory and quadrupedal locomotor groups, as well as high intrageneric variation within some taxa, particularly Pongo and Gorilla. However, as predicted, Homo sapiens, which rarely use their hands for locomotion and weight support, were unique in showing lower relative bone volume (BV/TV) compared with all other taxa. Furthermore, parameters used to quantify trabecular structure within the wrist scale with size generally following similar allometric patterns found in trabeculae of other mammalian skeletal elements. We discuss the challenges

  20. Fractal dimension and architecture of trabecular bone.

    Science.gov (United States)

    Fazzalari, N L; Parkinson, I H

    1996-01-01

    The fractal dimension of trabecular bone was determined for biopsies from the proximal femur of 25 subjects undergoing hip arthroplasty. The average age was 67.7 years. A binary profile of the trabecular bone in the biopsy was obtained from a digitized image. A program written for the Quantimet 520 performed the fractal analysis. The fractal dimension was calculated for each specimen, using boxes whose sides ranged from 65 to 1000 microns in length. The mean fractal dimension for the 25 subjects was 1.195 +/- 0.064 and shows that in Euclidean terms the surface extent of trabecular bone is indeterminate. The Quantimet 520 was also used to perform bone histomorphometric measurements. These were bone volume/total volume (BV/TV) (per cent) = 11.05 +/- 4.38, bone surface/total volume (BS/TV) (mm2/mm3) = 1.90 +/- 0.51, trabecular thickness (Tb.Th) (mm) = 0.12 +/- 0.03, trabecular spacing (Tb.Sp) (mm) = 1.03 +/- 0.36, and trabecular number (Tb.N) (number/mm) = 0.95 +/- 0.25. Pearsons' correlation coefficients showed a statistically significant relationship between the fractal dimension and all the histomorphometric parameters, with BV/TV (r = 0.85, P fractal dimension shows that trabecular bone exhibits fractal properties over a defined box size, which is within the dimensions of a structural unit for trabecular bone. Therefore, the fractal dimension of trabecular bone provides a measure which does not rely on Euclidean descriptors in order to describe a complex geometry.

  1. Trabecular bone of growth plate origin influences both trabecular and cortical morphology in adulthood.

    Science.gov (United States)

    Wang, Qingju; Ghasem-Zadeh, Ali; Wang, Xiao-Fang; Iuliano-Burns, Sandra; Seeman, Ego

    2011-07-01

    Skeletal fragility is common at metaphyseal regions of long bones. The cortices of this region are derived by coalescence of trabeculae around the periphery of the growth plate, not by periosteal apposition, as occurs in the diaphyses. We therefore hypothesized that trabecular bone in childhood predicted both cortical and trabecular morphology in adulthood. To test this hypothesis, we measured distal radial and tibial structure using high-resolution peripheral quantitative computed tomography in 61 daughter-mother pairs, mean age 12.5 years (range 7 to 19 years) and 44.1 years (range 32 to 50 years), respectively. The daughters' trabecular bone volume (BV/TV), thickness, number, and separation predicted the corresponding traits in their mothers. Their trabecular BV/TV also predicted their mothers' cortical thickness (r = 0.32, p = .02). By contrast, the daughters' cortical thickness did not predict their mothers' cortical thickness. The daughters had higher trabecular BV/TV than their mothers (mean ± SD, radius 0.134 ± 0.024 versus 0.124 ± 0.033, p = .03; tibia 0.145 ± 0.021 versus 0.135 ± 0.032, p < .01) owing to greater trabecular number, not thickness, and less trabecular separation. Abnormalities in the development of metaphyseal trabecular bone are likely to influence fragility in both trabecular and cortical bone of this region in adulthood.

  2. Immunohistochemical patterns of follicular dendritic cell meshwork and Ki-67 in small B-cell lymphomas

    Institute of Scientific and Technical Information of China (English)

    时云飞

    2013-01-01

    Objective To identify the immunohistochemical patterns of follicular dendritic cell(FDC)meshwork and Ki-67labeling index in small B-cell lymphomas(SBLs) and their significance in differential diagnosis.Methods

  3. An Orientation Distribution Function for Trabecular Bone

    Energy Technology Data Exchange (ETDEWEB)

    Lawrence Livermore National Laboratory

    2004-10-08

    We describe a new method for quantifying the orientation of trabecular bone from three-dimensional images. Trabecular lattices from five human vertebrae were decomposed into individual trabecular elements, and the orientation, mass, and thickness of each element were recorded. Continuous functions that described the total mass (M({var_phi},{theta})) and mean thickness ({tau}({var_phi},{theta})) of all trabeculae as a function of orientation were derived. The results were compared with experimental measurements of the elastic modulus in the three principal anatomic directions. A power law scaling relationship between the anisotropies in mass and elastic modulus was observed; the scaling exponent was 1.41 (R{sup 2} = 0.88). As expected, the preponderance of trabecular mass was oriented along the cranial-caudal direction; on average, there was 3.4 times more mass oriented vertically than horizontally. Moreover, the vertical trabeculae were 30% thicker, on average, than the horizontal trabeculae. The vertical trabecular thickness was inversely related to the connectivity (R{sup 2} = 0.70; p = 0.07), suggesting a possible organization into either few, thick trabeculae or many thin trabeculae. The method, which accounts for the mechanical connectedness of the lattice, provides a rapid way to both visualize and quantify the three-dimensional organization of trabecular bone.

  4. Material Properties of the Mandibular Trabecular Bone

    Science.gov (United States)

    Lakatos, Éva; Magyar, Lóránt; Bojtár, Imre

    2014-01-01

    The present paper introduces a numerical simulation aided, experimental method for the measurement of Young's modulus of the trabecular substance in the human mandible. Compression tests were performed on fresh cadaveric samples containing trabecular bone covered with cortical layer, thus avoiding the destruction caused by the sterilization, preservation, and storage and the underestimation of the stiffness resulting from the individual failure of the trabeculae cut on the surfaces. The elastic modulus of the spongiosa was determined by the numerical simulation of each compression test using a specimen specific finite element model of each sample. The received mandibular trabecular bone Young's modulus values ranged from 6.9 to 199.5 MPa. PMID:27006933

  5. Material Properties of the Mandibular Trabecular Bone

    Directory of Open Access Journals (Sweden)

    Éva Lakatos

    2014-01-01

    Full Text Available The present paper introduces a numerical simulation aided, experimental method for the measurement of Young’s modulus of the trabecular substance in the human mandible. Compression tests were performed on fresh cadaveric samples containing trabecular bone covered with cortical layer, thus avoiding the destruction caused by the sterilization, preservation, and storage and the underestimation of the stiffness resulting from the individual failure of the trabeculae cut on the surfaces. The elastic modulus of the spongiosa was determined by the numerical simulation of each compression test using a specimen specific finite element model of each sample. The received mandibular trabecular bone Young’s modulus values ranged from 6.9 to 199.5 MPa.

  6. The trabecular bypass stent in a pseudophakic glaucoma patient: A 1-year follow-up.

    Science.gov (United States)

    Fea, Antonio M; Dogliani, Monica; Machetta, Federica; Lale-Lacroix, Gabriella; Brogliatti, Beatrice; Grignolo, Federico M

    2008-12-01

    To describe the 1-year success of a trabecular stent implant in a pseudophakic glaucoma patient. The stent is implanted through a small corneal incision under gonioscopic control. Intraocular pressure control was reported in cultured human anterior segment. Observational case report. We report the case of a patient who was implanted and followed-up for 1 year at the Dipartimento di Fisiopatologia Clinica. The main outcome measures were intraocular pressure and visual field. The patient's intraocular pressure was controlled with topical beta-blockers for 6 months and without therapy for 6 months. Two diurnal curves demonstrated achievement of target pressure during the day. The 1-year visual field was unchanged. We are not aware of previous reports of trabecular stent implantation in pseudophakic patients. The trabecular stent had minimal peri-operative morbidity. Identification of the implantation site is challenging and reduction of efficacy over time may occur.

  7. Chloroplast actin filaments organize meshwork on the photorelocated chloroplasts in the moss Physcomitrella patens.

    Science.gov (United States)

    Yamashita, Hiroko; Sato, Yoshikatsu; Kanegae, Takeshi; Kagawa, Takatoshi; Wada, Masamitsu; Kadota, Akeo

    2011-02-01

    Cytoskeleton dynamics during phototropin-dependent chloroplast photorelocation movement was analyzed in protonemal cells of actin- and microtubule-visualized lines of Physcomitrella patens expressing GFP- or tdTomato-talin and GFP-tubulin. Using newly developed epi- and trans-microbeam irradiation systems that permit fluorescence observation of the cell under blue microbeam irradiation inducing chloroplast relocation, it was revealed that meshwork of actin filaments formed at the chloroplast-accumulating area both in the avoidance and accumulation movements. The structure disappeared soon when blue microbeam was turned off, and it was not induced under red microbeam irradiation that did not evoke chloroplast relocation movement. In contrast, no apparent change in microtubule organization was detected during the movements. The actin meshwork was composed of short actin filaments distinct from the cytoplasmic long actin cables and was present between the chloroplasts and plasma membrane. The short actin filaments emerged from around the chloroplast periphery towards the center of chloroplast. Showing highly dynamic behavior, the chloroplast actin filaments (cp-actin filaments) were rapidly organized into meshwork on the chloroplast surface facing plasma membrane. The actin filament configuration on a chloroplast led to the formation of actin meshwork area in the cell as the chloroplasts arrived at and occupied the area. After establishment of the meshwork, cp-actin filaments were still highly dynamic, showing appearance, disappearance, severing and bundling of filaments. These results indicate that the cp-actin filaments have significant roles in the chloroplast movement and positioning in the cell.

  8. Characterization of micro-invasive trabecular bypass stents by ex vivo perfusion and computational flow modeling

    Directory of Open Access Journals (Sweden)

    Hunter KS

    2014-03-01

    Full Text Available Kendall S Hunter,1 Todd Fjield,2 Hal Heitzmann,2 Robin Shandas,1 Malik Y Kahook3 1Department of Bioengineering, University of Colorado Denver, Aurora, CO, USA; 2Glaukos Corporation, Laguna Hills, CA, USA; 3University of Colorado Hospital Eye Center, Aurora, CO, USA Abstract: Micro-invasive glaucoma surgery with the Glaukos iStent® or iStent inject® (Glaukos Corporation, Laguna Hills, CA, USA is intended to create a bypass through the trabecular meshwork to Schlemm's canal to improve aqueous outflow through the natural physiologic pathway. While the iStent devices have been evaluated in ex vivo anterior segment models, they have not previously been evaluated in whole eye perfusion models nor characterized by computational fluid dynamics. Intraocular pressure (IOP reduction with the iStent was evaluated in an ex vivo whole human eye perfusion model. Numerical modeling, including computational fluid dynamics, was used to evaluate the flow through the stents over physiologically relevant boundary conditions. In the ex vivo model, a single iStent reduced IOP by 6.0 mmHg from baseline, and addition of a second iStent further lowered IOP by 2.9 mmHg, for a total IOP reduction of 8.9 mmHg. Computational modeling showed that simulated flow through the iStent or iStent inject is smooth and laminar at physiological flow rates. Each stent was computed to have a negligible flow resistance consistent with an expected significant decrease in IOP. The present perfusion results agree with prior clinical and laboratory studies to show that both iStent and iStent inject therapies are potentially titratable, providing clinicians with the opportunity to achieve lower target IOPs by implanting additional stents. Keywords: glaucoma, iStent, trabecular bypass, intraocular pressure, ab-interno, CFD

  9. Agreement between radiographic and photographic trabecular patterns

    Energy Technology Data Exchange (ETDEWEB)

    Korstjens, C.M.; Geraets, W.G.M.; Stelt, P.F. van der [Dept. of Oral Radiology, Academic Centre for Dentistry, Amsterdam (Netherlands); Spruijt, R.J. [Div. of Psychosocial Research and Epidemiology, Netherlands Cancer Inst., Amsterdam (Netherlands); Mosekilde, L. [Dept. of Cell Biology, Univ. of Aarhus (Denmark)

    1998-11-01

    Purpose: It has been hypothesized that photographs can facilitate the interpretation of the radiographic characteristics of trabecular bone. The reliability of these photographic and radiographic approaches has been determined, as have various agreements between the two approaches and their correlations with biomechanical characteristics. Material and Methods: Fourteen vertebral bodies were obtained at autopsy from 6 women and 8 men aged 22-76 years. Photographs (n=28) and radiographs (n=28) were taken of midsagittal slices from the third lumbar vertebra. The radiographs and photographs were digitized and the geometric properties of the trabecular architecture were then determined with a digital images analysis technique. Information on the compressive strength and ash density of the vertebral body was also available. Results: The geometric properties of both radiographs and photographs could be measured with a high degree of reliability (Cronbach`s {alpha}>0.85). Agreement between the radiographic and photographic approaches was mediocre as only the radiographic measurements showed insignificant correlations (p<0.05) with the biomechanical characteristics. We suggest that optical phenomena may result in the significant correlations between the photographs and the biomechanical characteristics. Conclusion: For digital image processing, radiography offers a superior description of the architecture of trabecular bone to that offered by photography. (orig.)

  10. Trabecular Plate Loss and Deteriorating Elastic Modulus of Femoral Trabecular Bone in Intertrochanteric Hip Fractures

    Institute of Scientific and Technical Information of China (English)

    Ji Wang; Bin Zhou; Ian Parkinson; C. David L. Thomas; John G. Clement; Nick Fazzalari; X. Edward Guo

    2013-01-01

    Osteoporotic hip fracture is associated with significant trabecular bone loss, which is typically characterized as low bone density by dual-energy X-ray absorptiometry (DXA) and altered microstructure by micro-computed tomography (µCT). Emerging morphological analysis techniques, e.g. individual trabecula segmentation (ITS), can provide additional insights into changes in plate-like and rod-like trabeculae, two major micro-structural types serving different roles in determining bone strength. Using ITS, we evaluated trabecular microstructure of intertrochanteric bone cores obtained from 23 patients undergoing hip replacement surgery for intertrochanteric fracture and 22 cadaveric controls. Micro-finite element (µFE) analyses were performed to further understand how the abnormalities seen by ITS might translate into effects on bone strength. ITS analyses revealed that, near fracture site, plate-like trabeculae were seriously depleted in fracture patients, but trabecular rod volume was maintained. Besides, decreased plate area and rod length were observed in fracture patients. Fracture patients also showed decreased elastic moduli and shear moduli of trabecular bone. These results provided evidence that in intertrochanteric hip fracture, preferential loss of plate-like trabeculae led to more rod-like microstructure and deteriorated mechanical competence adjacent to the fracture site, which increased our understanding of the biomechanical pathogenesis of hip fracture in osteoporosis.

  11. Trabecular network arrangement within the human patella: how osteoarthritis remodels the 3D trabecular structure

    Science.gov (United States)

    Hoechel, Sebastian; Deyhle, Hans; Toranelli, Mireille; Müller-Gerbl, Magdalena

    2016-10-01

    Following the principles of "morphology reveals biomechanics", the anatomical structure of the cartilage-osseous interface and the supporting trabecular network show defined adaptation in their architectural properties to physiological loading. In case of a faulty relationship, the ability to support the load diminishes and the onset of osteoarthritis (OA) may arise and disturb the balanced formation and resorption processes. To describe and quantify the changes occurring, 10 human OA patellae were analysed concerning the architectural parameters of the trabecular network within the first five mms by the evaluation of 3Dmicro-CT datasets. The analysed OA-samples showed a strong irregularity for all trabecular parameters across the trabecular network, no regularity in parameter distribution was found. In general, we saw a decrease of material in the OA population as BV/TV, BS/TV, Tb.N and Tb.Th were decreased and the spacing increased. The development into depth showed a logarithmic dependency, which revealed the greatest difference for all parameters within the first mm in comparison to the physiologic samples. The differences decreased towards the 5th mm. The interpretation of the mathematic dependency leads to the conclusion that the main impact of OA is beneath the subchondral bone plate (SBP) and lessens with depth. Next to the clear difference in material, the architectural arrangement is more rod-like and isotropic just beneath the SBP in comparison to the plate-like and more anisotropic physiological arrangement.

  12. Fisiología trabecular y glaucoma de ángulo abierto Trabecular physiology and open angle glaucoma

    OpenAIRE

    Yoanner Martín Perera; Ibraín Piloto Díaz; Germán Álvarez Cisneros; Francisco Fumero González; Darlen Rodríguez Rivero; Lizet Sánchez Acosta

    2012-01-01

    El glaucoma constituye una de las enfermedades oculares más frecuentes en el mundo. Su etiología es variada, pero el problema radica generalmente en la evacuación del humor acuoso a nivel de la red trabecular y del canal de Schlemm. Se realizó una revisión bibliográfica sobre los principales mecanismos envueltos en la función trabecular: capacidad fagocítica de las células trabeculares, regulación de la composición de la matriz extracelular, contracción-relajación de las células trabeculares ...

  13. Incorporation of Tenascin-C into the Extracellular Matrix by Periostin Underlies an Extracellular Meshwork Architecture*

    OpenAIRE

    Kii, Isao; Nishiyama, Takashi; Li, Minqi; Matsumoto, Ken-Ichi; Saito, Mitsuru; Amizuka, Norio; Kudo, Akira

    2009-01-01

    Extracellular matrix (ECM) underlies a complicated multicellular architecture that is subjected to significant forces from mechanical environment. Although various components of the ECM have been enumerated, mechanisms that evolve the sophisticated ECM architecture remain to be addressed. Here we show that periostin, a matricellular protein, promotes incorporation of tenascin-C into the ECM and organizes a meshwork architecture of the ECM. We found that both periostin null mice and tenascin-C...

  14. Trabecular architecture analysis in femur radiographic images using fractals.

    Science.gov (United States)

    Udhayakumar, G; Sujatha, C M; Ramakrishnan, S

    2013-04-01

    Trabecular bone is a highly complex anisotropic material that exhibits varying magnitudes of strength in compression and tension. Analysis of the trabecular architectural alteration that manifest as loss of trabecular plates and connection has been shown to yield better estimation of bone strength. In this work, an attempt has been made toward the development of an automated system for investigation of trabecular femur bone architecture using fractal analysis. Conventional radiographic femur bone images recorded using standard protocols are used in this study. The compressive and tensile regions in the images are delineated using preprocessing procedures. The delineated images are analyzed using Higuchi's fractal method to quantify pattern heterogeneity and anisotropy of trabecular bone structure. The results show that the extracted fractal features are distinct for compressive and tensile regions of normal and abnormal human femur bone. As the strength of the bone depends on architectural variation in addition to bone mass, this study seems to be clinically useful.

  15. Hyalinising trabecular adenoma of the thyroid.

    Directory of Open Access Journals (Sweden)

    Sara NINAN

    2011-12-01

    Full Text Available Hyalinising trebecular adenoma (HTA of the thyroid is rare and controversies remain regarding the diagnosis and management. It is an uncommon benign thyroid tumour that can present as a solitary thyroid nodule, a prominent nodule in a multinodular goitre, or as an incidental finding in a thyroidectomy specimen. Some considered HTA a unique entity, while others have proved it to be a variant of papillary carcinoma or have considered it a nonspecific pattern that may be seen with a variety of thyroid lesions. We report the case of a 31-year-old Chinese lady who presented with four years history of right sided goitre that was gradually increasing in size. Fine needle aspiration cytology showed appearances of follicular adenoma. Intra-operative frozen section histology of the excised right thyroid lobe was reported as trabecular adenoma which was confirmed with histopathological examination.

  16. The three-dimensional organisation of the post-trabecular aqueous outflow pathway and limbal vasculature in the mouse.

    Science.gov (United States)

    van der Merwe, Elizabeth L; Kidson, Susan H

    2014-08-01

    The mouse eye has been used as a model for studies on the microanatomy of the outflow pathways but most of what is known comes from histological sections. These studies have focused mainly on the morphological features of the trabecular meshwork, Schlemm's canal and aqueous channels that link to the superficial episcleral vasculature. However, the anatomical architecture of the aqueous outflow vessels and their relationship to each other and to the general vascular circulation is not well understood. The aim of this study was to provide a detailed description of the microarchitecture of the aqueous outflow vessels and their relationship to the superficial limbal/episcleral vasculature throughout the entire limbus. The aqueous outflow vessels and blood and lymphatic vessels were imaged in PECAM-1 and LYVE-1 immunostained whole anterior segments of adult mice and three-dimensional (3-D) reconstructions of the optical sections were generated to reveal the aqueous, blood and lymphatic architecture. The arterial supply, venous drainage, organisation of perilimbal vasculature, collector channels/aqueous veins and the morphology of Schlemm's canal were revealed in their entirety and the relationships between these structures is described. Schlemm's canal was PECAM-1 positive but there was no affinity for the lymphatic marker LYVE-1. We show that Schlemm's canal is a continuous circular structure and more often seen as a single, broad, varicose vessel with short regions appearing as a plexus. Aqueous veins link Schlemm's canal to the superficial vasculature and there were no direct links seen between the canal and the lymphatic vessels.

  17. 猪眼经内路准分子激光小梁部分切除术后的形态学研究%Morphologic study on trabecular meshwork after excimer laser trabecular ablation ab interno in miniature pigs

    Institute of Scientific and Technical Information of China (English)

    吴慧娟; 鲍永珍

    2006-01-01

    目的 研究中国实验用小型猪眼在经内路准分子激光小梁部分切除术(ELT)后,小梁网在一段时间内的形态学变化.方法 对4只小型猪行ELT,分别于术后1 h、3 d、1周和1个月取眼球,并分别行光学显微镜和扫描电子显微镜的形态学观察.结果 光学显微镜观察发现,在术后1 h、3 d和1周时,有从前房到Schlemm's管的通道形成,在术后1个月时有持续的小梁网组织的消融.术后1 h时激光作用部位有少量渗出,直到1个月时未见到明显的纤维增生现象.扫描电子显微镜观察发现,4个阶段的标本均可看到小梁网上的直径为200μm或400μm的洞样结构缺损,在1周和1个月的标本中,可以看到在洞的边缘有轻微的组织愈合缘.结论 ELT可以形成前房到Schlemm's管的通道,且激光引起的组织消融的作用在术后1个月内持续存在.

  18. Particle migration and gap healing around trabecular metal implants

    DEFF Research Database (Denmark)

    Rahbek, O; Kold, S; Zippor, B;

    2005-01-01

    Bone on-growth and peri-implant migration of polyethylene particles were studied in an experimental setting using trabecular metal and solid metal implants. Cylindrical implants of trabecular tantalum metal and solid titanium alloy implants with a glass bead blasted surface were inserted either...... in an exact surgical fit or with a peri-implant gap into a canine knee joint. We used a randomised paired design. Polyethylene particles were injected into the knee joint. In both types of surgical fit we found that the trabecular metal implants had superior bone ongrowth in comparison with solid metal...... implants (exact fit: 23% vs. 7% [p=0.02], peri-implant gap: 13% vs. 0% [p=0.02]. The number of peri-implant polyethylene particles was significantly reduced around the trabecular metal implants with a peri-implant gap compared with solid implants....

  19. Incorporation of tenascin-C into the extracellular matrix by periostin underlies an extracellular meshwork architecture.

    Science.gov (United States)

    Kii, Isao; Nishiyama, Takashi; Li, Minqi; Matsumoto, Ken-Ichi; Saito, Mitsuru; Amizuka, Norio; Kudo, Akira

    2010-01-15

    Extracellular matrix (ECM) underlies a complicated multicellular architecture that is subjected to significant forces from mechanical environment. Although various components of the ECM have been enumerated, mechanisms that evolve the sophisticated ECM architecture remain to be addressed. Here we show that periostin, a matricellular protein, promotes incorporation of tenascin-C into the ECM and organizes a meshwork architecture of the ECM. We found that both periostin null mice and tenascin-C null mice exhibited a similar phenotype, confined tibial periostitis, which possibly corresponds to medial tibial stress syndrome in human sports injuries. Periostin possessed adjacent domains that bind to tenascin-C and the other ECM protein: fibronectin and type I collagen, respectively. These adjacent domains functioned as a bridge between tenascin-C and the ECM, which increased deposition of tenascin-C on the ECM. The deposition of hexabrachions of tenascin-C may stabilize bifurcations of the ECM fibrils, which is integrated into the extracellular meshwork architecture. This study suggests a role for periostin in adaptation of the ECM architecture in the mechanical environment.

  20. Mechanical properties of femoral trabecular bone in dogs

    Directory of Open Access Journals (Sweden)

    Nolte Ingo

    2005-03-01

    Full Text Available Abstract Background Studying mechanical properties of canine trabecular bone is important for a better understanding of fracture mechanics or bone disorders and is also needed for numerical simulation of canine femora. No detailed data about elastic moduli and degrees of anisotropy of canine femoral trabecular bone has been published so far, hence the purpose of this study was to measure the elastic modulus of trabecular bone in canine femoral heads by ultrasound testing and to assess whether assuming isotropy of the cancellous bone in femoral heads in dogs is a valid simplification. Methods From 8 euthanized dogs, both femora were obtained and cubic specimens were cut from the centre of the femoral head which were oriented along the main pressure and tension trajectories. The specimens were tested using a 100 MHz ultrasound transducer in all three orthogonal directions. The directional elastic moduli of trabecular bone tissue and degrees of anisotropy were calculated. Results The elastic modulus along principal bone trajectories was found to be 11.2 GPa ± 0.4, 10.5 ± 2.1 GPa and 10.5 ± 1.8 GPa, respectively. The mean density of the specimens was 1.40 ± 0.09 g/cm3. The degrees of anisotropy revealed a significant inverse relationship with specimen densities. No significant differences were found between the elastic moduli in x, y and z directions, suggesting an effective isotropy of trabecular bone tissue in canine femoral heads. Discussion This study presents detailed data about elastic moduli of trabecular bone tissue obtained from canine femoral heads. Limitations of the study are the relatively small number of animals investigated and the measurement of whole specimen densities instead of trabecular bone densities which might lead to an underestimation of Young's moduli. Publications on elastic moduli of trabecular bone tissue present results that are similar to our data. Conclusion This study provides data about directional elastic

  1. Massive acetabular bone loss: Limits of trabecular metal cages

    Directory of Open Access Journals (Sweden)

    Villanueva-Martínez Manuel

    2011-01-01

    Full Text Available Massive acetabular bone loss (more than 50% of the acetabular area can result in insufficient native bone for stable fixation and long-term bone ingrowth of conventional porous cups. The development of trabecular metal cages with osteoconductive properties may allow a more biological and versatile approach that will help restore bone loss, thus reducing the frequency of implant failure in the short-to-medium term. We report a case of massive bone loss affecting the dome of the acetabulum and the ilium, which was treated with a trabecular metal cage and particulate allograft. Although the trabecular metal components had no intrinsic stability, they did enhance osseointegration and incorporation of a non-impacted particulate graft, thus preventing failure of the reconstruction. The minimum 50% contact area between the native bone and the cup required for osseointegration with the use of porous cups may not hold for new trabecular metal cups, thus reducing the need for antiprotrusio cages. The osteoconductive properties of trabecular metal enhanced allograft incorportation and iliac bone rebuilding without the need to fill the defect with multiple wedges nor protect the reconstruction with an antiprotrusio cage.

  2. FRACTAL ANALYSIS OF TRABECULAR BONE: A STANDARDISED METHODOLOGY

    Directory of Open Access Journals (Sweden)

    Ian Parkinson

    2011-05-01

    Full Text Available A standardised methodology for the fractal analysis of histological sections of trabecular bone has been established. A modified box counting method has been developed for use on a PC based image analyser (Quantimet 500MC, Leica Cambridge. The effect of image analyser settings, magnification, image orientation and threshold levels, was determined. Also, the range of scale over which trabecular bone is effectively fractal was determined and a method formulated to objectively calculate more than one fractal dimension from the modified Richardson plot. The results show that magnification, image orientation and threshold settings have little effect on the estimate of fractal dimension. Trabecular bone has a lower limit below which it is not fractal (λ<25 μm and the upper limit is 4250 μm. There are three distinct fractal dimensions for trabecular bone (sectional fractals, with magnitudes greater than 1.0 and less than 2.0. It has been shown that trabecular bone is effectively fractal over a defined range of scale. Also, within this range, there is more than 1 fractal dimension, describing spatial structural entities. Fractal analysis is a model independent method for describing a complex multifaceted structure, which can be adapted for the study of other biological systems. This may be at the cell, tissue or organ level and compliments conventional histomorphometric and stereological techniques.

  3. Trabecular bone structure and strength - remodelling and repair

    DEFF Research Database (Denmark)

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

    2000-01-01

    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...... through osteoclastic perforations of horizontal struts. 2) There is an increase in anisotropy - again due to loss of horizontal struts, and perhaps also due to micro-modelling drift or to thickening of some vertical trabeculae. 3) The changes in the network can lead to the slenderness ratio between...... can never be isolated in vivo, other factors need to be investigated: The interplay between the cortical shell and the trabecular network; transmission of load; the interplay between soft tissues (cartilage, connective tissue, muscle) and bone; the shock absorbing capacity of the discs...

  4. Microsurgical anatomy of the infratentorial trabecular membranes and subarachnoid cisterns.

    Science.gov (United States)

    Vinas, F C; Dujovny, M; Fandino, R; Chavez, V

    1996-04-01

    The understanding of the anatomy of the subarachnoid cisterns and trabecular membranes is of paramount importance in the surgical treatment of pathology of the posterior fossa. Aneurysms, arteriovenous malformations, and some tumors should be approached through the subarachnoid space. The subarachnoid cisterns provide natural pathways to approach neurovascular and cranial nerve structures. The microsurgical anatomy of the infratentorial subarachnoid cisterns was studied in twenty adult brains, using the 'immersion technique'. Air was injected into the subarachnoid cisterns and brains were dissected under the operative microscope. Six main compartmental trabecular membranes were identified in the infratentorial level. They divide the subarachnoid space into six cisterns. Cisternal divisions and the disposition of the trabecular membranes were closely related to the vascular divisional patterns of the principal arteries. Thorough knowledge of the microsurgical anatomy of the subarachnoid space will aid neurosurgeons during the surgical approach of many vascular and tumoral lesions located in the posterior fossa.

  5. Microsurgical anatomy of the supratentorial arachnoidal trabecular membranes and cisterns.

    Science.gov (United States)

    Vinas, F C; Fandino, R; Dujovny, M; Chavez, V

    1994-12-01

    We examined the microsurgical anatomy of the supratentorial subarachnoid cisterns with a surgical microscope in 20 brains prepared using the immersion technique. The adult brains were immersed in Ringer's solution and air was injected into the subarachnoid cisterns while the brains remained submerged in solution. We identified nine trabecular membranes that limit the 15 cisterns. We specifically looked at the anatomical relationship between the supratentorial trabecular membranes and cisterns to their corresponding vessels and cranial nerves. The cistern divisions and the dispositions of trabecular membranes were closely related to the vascular division patterns of the principal brain arteries. A clear and thorough understanding of the neuroanatomical structures of the subarachnoid cisterns is important because they provide natural pathways to neurovascular and cranial nerve structures. These pathways allow access to intracranial arteries, veins, and nerves during microvascular procedures without disturbing surrounding important brain structures.

  6. Lack of BRAF mutations in hyalinizing trabecular neoplasm

    Directory of Open Access Journals (Sweden)

    Brose Marcia

    2006-01-01

    Full Text Available Abstract The hyalinizing trabecular neoplasm (HTN of the thyroid is an unusual and controversial lesion. Some consider it a peculiar type of papillary thyroid carcinoma (PTC because of its nuclear features and presence of psammoma bodies. Others consider it an adenoma. Molecular studies have found RET/PTC translocations in some examples, supporting HTN as a PTC; however mutations in BRAF (another marker for PTC have not been found. We report two cases of classic HTN and a case of trabecular PTC and show BRAF mutations in the latter and not in HTN. Trabecular growth pattern is insufficient for a diagnosis of HTN and lesions with such a pattern and nuclear features of PTC are cancers. Morphologically classic HTN are not associated with metastatic potential and should be considered adenomas.

  7. Long range node-strut analysis of trabecular bone microarchitecture

    DEFF Research Database (Denmark)

    Schmah, Tanya; Marwan, Norbert; Thomsen, Jesper Skovhus

    2011-01-01

    of the trabecular bone network. METHODS: Similar in some ways to the topological node-strut analysis introduced by Garrahan et al. [J. Microsc. 142, 341-349 (1986)], our method is distinguished by an emphasis on long-range trabecular connectivity. Thus, while the topological classification of a pixel (after...... skeletonization) as a node, strut, or terminus, can be determined from the 3 × 3 neighborhood of that pixel, our method, which does not involve skeletonization, takes into account a much larger neighborhood. In addition, rather than giving a discrete classification of each pixel as a node, strut, or terminus, our...

  8. Comparison of optical coherence tomography, microcomputed tomography, and histology at a three-dimensionally imaged trabecular bone sample

    Science.gov (United States)

    Kasseck, Christoph; Kratz, Marita; Torcasio, Antonia; Gerhardt, Nils C.; van Lenthe, G. Harry; Gambichler, Thilo; Hoffmann, Klaus; Jones, David B.; Hofmann, Martin R.

    2010-07-01

    We investigate optical coherence tomography (OCT) as a method for imaging bone. The OCT images are compared directly to those of the standard methods of bone histology and microcomputed tomography (μCT) on a single, fixed human femoral trabecular bone sample. An advantage of OCT over bone histology is its noninvasive nature. OCT also images the lamellar structure of trabeculae at slightly higher contrast than normal bone histology. While μCT visualizes the trabecular framework of the whole sample, OCT can image additionally cells with a penetration depth limited approximately to 1 mm. The most significant advantage of OCT, however, is the absence of toxic effects (no ionizing radiation), i.e., continuous images may be made and individual cell tracking may be performed. The penetration depth of OCT, however, limits its use to small animal models and small bone organ cultures.

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

    Science.gov (United States)

    Fan, Ruoxun; 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. PMID:27403206

  10. Long range node-strut analysis of trabecular bone microarchitecture

    DEFF Research Database (Denmark)

    Schmah, Tanya; Marwan, Norbert; Thomsen, Jesper Skovhus

    2011-01-01

    PURPOSE: We present a new morphometric measure of trabecular bone microarchitecture, called mean node strength (NdStr), which is part of a newly developed approach called long range node-strut analysis. Our general aim is to describe and quantify the apparent "latticelike" microarchitecture of th...

  11. Age variations in the properties of human tibial trabecular bone

    DEFF Research Database (Denmark)

    Ding, Ming; Dalstra, M; Danielsen, CC;

    1997-01-01

    We tested in compression specimens of human proximal tibial trabecular bone from 31 normal donors aged from 16 to 83 years and determined the mechanical properties, density and mineral and collagen content. Young's modulus and ultimate stress were highest between 40 and 50 years, whereas ultimate...

  12. Determinants of microdamage in elderly human vertebral trabecular bone.

    Directory of Open Access Journals (Sweden)

    Hélène Follet

    Full Text Available Previous studies have shown that microdamage accumulates in bone as a result of physiological loading and occurs naturally in human trabecular bone. The purpose of this study was to determine the factors associated with pre-existing microdamage in human vertebral trabecular bone, namely age, architecture, hardness, mineral and organic matrix. Trabecular bone cores were collected from human L2 vertebrae (n = 53 from donors 54-95 years of age (22 men and 30 women, 1 unknown and previous cited parameters were evaluated. Collagen cross-link content (PYD, DPD, PEN and % of collagen was measured on surrounding trabecular bone. We found that determinants of microdamage were mostly the age of donors, architecture, mineral characteristics and mature enzymatic cross-links. Moreover, linear microcracks were mostly associated with the bone matrix characteristics whereas diffuse damage was associated with architecture. We conclude that linear and diffuse types of microdamage seemed to have different determinants, with age being critical for both types.

  13. 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, un...

  14. Quantifying Changes in the Spatial Structure of Trabecular Bone

    CERN Document Server

    Marwan, Norbert; Felsenberg, Dieter; Saparin, Peter; Kurths, Jürgen

    2010-01-01

    We apply recently introduced measures of complexity for the structural quantfication of distal tibial bone. For the first time, we are able to investigate the temporal structural alteration of trabecular bone. Based on four patients, we show how bone may alter due to temporal immobilisation.

  15. Radiographic features of mandibular trabecular bone structure in hypodontia

    NARCIS (Netherlands)

    Créton, M.; Geraets, W.; Verhoeven, J.W.; van der Stelt, P.F.; Verhey, H.; Cune, M.

    2012-01-01

    Purpose: Radiographic parameters of mandibular trabecular bone structure between 67 subjects having hypodontia and those without were studied on digital panoramic radiographs. Materials and Methods: Three regions of interest (ROI) were defined: the ascending ramus, apical of the mandibular molar and

  16. Radiographic features of mandibular trabecular bone structure in hypodontia

    NARCIS (Netherlands)

    M. Créton; W. Geraets; J.W. Verhoeven; P.F. van der Stelt; H. Verhey; M. Cune

    2012-01-01

    Purpose: Radiographic parameters of mandibular trabecular bone structure between 67 subjects having hypodontia and those without were studied on digital panoramic radiographs. Materials and Methods: Three regions of interest (ROI) were defined: the ascending ramus, apical of the mandibular molar and

  17. Radiographic Features of Mandibular Trabecular Bone Structure in Hypodontia

    NARCIS (Netherlands)

    Creton, Marijn; Geraets, Wil; Verhoeven, Jan Willem; van der Stelt, Paul F.; Verhey, Hans; Cune, Marco

    2012-01-01

    Purpose: Radiographic parameters of mandibular trabecular bone structure between 67 subjects having hypodontia and those without were studied on digital panoramic radiographs. Materials and Methods: Three regions of interest (ROI) were defined: the ascending ramus, apical of the mandibular molar and

  18. Anorexia Nervosa: Analysis of Trabecular Texture with CT.

    Science.gov (United States)

    Tabari, Azadeh; Torriani, Martin; Miller, Karen K; Klibanski, Anne; Kalra, Mannudeep K; Bredella, Miriam A

    2016-10-31

    Purpose To determine indexes of skeletal integrity by using computed tomographic (CT) trabecular texture analysis of the lumbar spine in patients with anorexia nervosa and normal-weight control subjects and to determine body composition predictors of trabecular texture. Materials and Methods This cross-sectional study was approved by the institutional review board and compliant with HIPAA. Written informed consent was obtained. The study included 30 women with anorexia nervosa (mean age ± standard deviation, 26 years ± 6) and 30 normal-weight age-matched women (control group). All participants underwent low-dose single-section quantitative CT of the L4 vertebral body with use of a calibration phantom. Trabecular texture analysis was performed by using software. Skewness (asymmetry of gray-level pixel distribution), kurtosis (pointiness of pixel distribution), entropy (inhomogeneity of pixel distribution), and mean value of positive pixels (MPP) were assessed. Bone mineral density and abdominal fat and paraspinal muscle areas were quantified with quantitative CT. Women with anorexia nervosa and normal-weight control subjects were compared by using the Student t test. Linear regression analyses were performed to determine associations between trabecular texture and body composition. Results Women with anorexia nervosa had higher skewness and kurtosis, lower MPP (P anorexia nervosa. Conclusion Patients with anorexia nervosa had increased skewness and kurtosis and decreased entropy and MPP compared with normal-weight control subjects. These parameters were associated with lowest lifetime weight and duration of amenorrhea, but there were no such associations with bone mineral density. These findings suggest that trabecular texture analysis might contribute information about bone health in anorexia nervosa that is independent of that provided with bone mineral density. (©) RSNA, 2016.

  19. Prediction of trabecular bone qualitative properties using scanning quantitative ultrasound

    Science.gov (United States)

    Qin, Yi-Xian; Lin, Wei; Mittra, Erik; Xia, Yi; Cheng, Jiqi; Judex, Stefan; Rubin, Clint; Müller, Ralph

    2012-01-01

    Microgravity induced bone loss represents a critical health problem in astronauts, particularly occurred in weight-supporting skeleton, which leads to osteopenia and increase of fracture risk. Lack of suitable evaluation modality makes it difficult for monitoring skeletal status in long term space mission and increases potential risk of complication. Such disuse osteopenia and osteoporosis compromise trabecular bone density, and architectural and mechanical properties. While X-ray based imaging would not be practical in space, quantitative ultrasound may provide advantages to characterize bone density and strength through wave propagation in complex trabecular structure. This study used a scanning confocal acoustic diagnostic and navigation system (SCAN) to evaluate trabecular bone quality in 60 cubic trabecular samples harvested from adult sheep. Ultrasound image based SCAN measurements in structural and strength properties were validated by μCT and compressive mechanical testing. This result indicated a moderately strong negative correlations observed between broadband ultrasonic attenuation (BUA) and μCT-determined bone volume fraction (BV/TV, R2=0.53). Strong correlations were observed between ultrasound velocity (UV) and bone’s mechanical strength and structural parameters, i.e., bulk Young’s modulus (R2=0.67) and BV/TV (R2=0.85). The predictions for bone density and mechanical strength were significantly improved by using a linear combination of both BUA and UV, yielding R2=0.92 for BV/TV and R2=0.71 for bulk Young’s modulus. These results imply that quantitative ultrasound can characterize trabecular structural and mechanical properties through measurements of particular ultrasound parameters, and potentially provide an excellent estimation for bone’s structural integrity. PMID:23976803

  20. Cortical and trabecular load sharing in the human femoral neck.

    Science.gov (United States)

    Nawathe, Shashank; Nguyen, Bich Phuong; Barzanian, Nasim; Akhlaghpour, Hosna; Bouxsein, Mary L; Keaveny, Tony M

    2015-03-18

    The relative role of the cortical vs trabecular bone in the load-carrying capacity of the proximal femur-a fundamental issue in both basic-science and clinical biomechanics-remains unclear. To gain insight into this issue, we performed micro-CT-based, linear elastic finite element analysis (61.5-micron-sized elements; ~280 million elements per model) on 18 proximal femurs (5M, 13F, ages 61-93 years) to quantify the fraction of frontal-plane bending moment shared by the cortical vs trabecular bone in the femoral neck, as well as the associated spatial distributions of stress. Analyses were performed separately for a sideways fall and stance loading. For both loading modes and across all 18 bones, we found consistent patterns of load-sharing in the neck: most proximally, the trabecular bone took most of the load; moving distally, the cortical bone took increasingly more of the load; and more distally, there was a region of uniform load-sharing, the cortical bone taking the majority of the load. This distal region of uniform load-sharing extended more for fall than stance loading (77 ± 8% vs 51 ± 6% of the neck length for fall vs. stance; mean ± SD) but the fraction of total load taken by the cortical bone in that region was greater for stance loading (88 ± 5% vs. 64 ± 9% for stance vs. fall). Locally, maximum stress levels occurred in the cortical bone distally, but in the trabecular bone proximally. Although the distal cortex showed qualitative stress distributions consistent with the behavior of an Euler-type beam, quantitatively beam theory did not apply. We conclude that consistent and well-delineated regions of uniform load-sharing and load-transfer between the cortical and trabecular bone exist within the femoral neck, the details of which depend on the external loading conditions.

  1. Prediction of trabecular bone qualitative properties using scanning quantitative ultrasound

    Science.gov (United States)

    Qin, Yi-Xian; Lin, Wei; Mittra, Erik; Xia, Yi; Cheng, Jiqi; Judex, Stefan; Rubin, Clint; Müller, Ralph

    2013-11-01

    Microgravity induced bone loss represents a critical health problem in astronauts, particularly occurred in weight-supporting skeleton, which leads to osteopenia and increase of fracture risk. Lack of suitable evaluation modality makes it difficult for monitoring skeletal status in long term space mission and increases potential risk of complication. Such disuse osteopenia and osteoporosis compromise trabecular bone density, and architectural and mechanical properties. While X-ray based imaging would not be practical in space, quantitative ultrasound may provide advantages to characterize bone density and strength through wave propagation in complex trabecular structure. This study used a scanning confocal acoustic diagnostic and navigation system (SCAN) to evaluate trabecular bone quality in 60 cubic trabecular samples harvested from adult sheep. Ultrasound image based SCAN measurements in structural and strength properties were validated by μCT and compressive mechanical testing. This result indicated a moderately strong negative correlations observed between broadband ultrasonic attenuation (BUA) and μCT-determined bone volume fraction (BV/TV, R2=0.53). Strong correlations were observed between ultrasound velocity (UV) and bone's mechanical strength and structural parameters, i.e., bulk Young's modulus (R2=0.67) and BV/TV (R2=0.85). The predictions for bone density and mechanical strength were significantly improved by using a linear combination of both BUA and UV, yielding R2=0.92 for BV/TV and R2=0.71 for bulk Young's modulus. These results imply that quantitative ultrasound can characterize trabecular structural and mechanical properties through measurements of particular ultrasound parameters, and potentially provide an excellent estimation for bone's structural integrity.

  2. Creep of trabecular bone from the human proximal tibia

    Energy Technology Data Exchange (ETDEWEB)

    Novitskaya, Ekaterina, E-mail: eevdokim@ucsd.edu [Mechanical and Aerospace Engineering, UC, San Diego, La Jolla, CA 92093 (United States); Materials Science and Engineering Program, UC, San Diego, La Jolla, CA 92093 (United States); Zin, Carolyn [Materials Science and Engineering, Johns Hopkins University, Baltimore, MD 21218 (United States); Chang, Neil; Cory, Esther; Chen, Peter [Departments of Bioengineering and Orthopaedic Surgery, UC, San Diego, La Jolla, CA 92093 (United States); D’Lima, Darryl [Shiley Center for Orthopaedic Research and Education, Scripps Health, La Jolla, CA 92037 (United States); Sah, Robert L. [Materials Science and Engineering Program, UC, San Diego, La Jolla, CA 92093 (United States); Departments of Bioengineering and Orthopaedic Surgery, UC, San Diego, La Jolla, CA 92093 (United States); McKittrick, Joanna [Mechanical and Aerospace Engineering, UC, San Diego, La Jolla, CA 92093 (United States); Materials Science and Engineering Program, UC, San Diego, La Jolla, CA 92093 (United States)

    2014-07-01

    Creep is the deformation that occurs under a prolonged, sustained load and can lead to permanent damage in bone. Creep in bone is a complex phenomenon and varies with type of loading and local mechanical properties. Human trabecular bone samples from proximal tibia were harvested from a 71-year old female cadaver with osteoporosis. The samples were initially subjected to one cycle load up to 1% strain to determine the creep load. Samples were then loaded in compression under a constant stress for 2 h and immediately unloaded. All tests were conducted with the specimens soaked in phosphate buffered saline with proteinase inhibitors at 37 °C. Steady state creep rate and final creep strain were estimated from mechanical testing and compared with published data. The steady state creep rate correlated well with values obtained from bovine tibial and human vertebral trabecular bone, and was higher for lower density samples. Tissue architecture was analyzed by micro-computed tomography (μCT) both before and after creep testing to assess creep deformation and damage accumulated. Quantitative morphometric analysis indicated that creep induced changes in trabecular separation and the structural model index. A main mode of deformation was bending of trabeculae. - Highlights: • Compressive creep tests of human trabecular bone across the tibia were performed. • The creep rate was found to be inversely proportional to the density of the samples. • μ-computed tomography before and after testing identified regions of deformation. • Bending of the trabeculae was found to be the main deformation mode.

  3. Long range node-strut analysis of trabecular bone microarchitecture

    CERN Document Server

    Schmah, T; Thomsen, J S; Saparin, P

    2015-01-01

    Purpose: We present a new morphometric measure of trabecular bone microarchitecture, called mean node strength (NdStr), which is part of a newly developed approach called long range node-strut analysis. Our general aim is to describe and quantify the apparent "latticelike" microarchitecture of the trabecular bone network. Methods: Similar in some ways to the topological node-strut analysis introduced by Garrahan et al. [J. Microsc. 142, 341-349 (1986)], our method is distinguished by an emphasis on long-range trabecular connectivity. Thus, while the topological classification of a pixel (after skeletonization) as a node, strut, or terminus, can be determined from the 3x3 neighborhood of that pixel, our method, which does not involve skeletonization, takes into account a much larger neighborhood. In addition, rather than giving a discrete classification of each pixel as a node, strut, or terminus, our method produces a continuous variable, node strength. The node strength is averaged over a region of interest ...

  4. Histomorphometry of Trabecular Bone of Caudal Vertebrae During Rat Pregnancy

    Directory of Open Access Journals (Sweden)

    S.M. Shahtaheri

    2003-04-01

    Full Text Available Pregnancy make demands upon maternal calcium hemeostasis and the extent to which the maternal bone mass is effected remains uncertain. Recently changes in the bone mass during human pregnancy have been associated also with the transformation of the cancellous architecture and the bone surface available for exchange. These jistomorphometrical structural changes were examined further in an animal model. Using uniparous laboratory rats fed at libitum, the histomorphometry of cancellous bone was compared in undecalcified of caudal vertebrae. Between 3 and 6 sections (8 m were analysed by an automated trabecular analysis system (TAS which measures a comprehensive range of structural variables including the trabecular separation, number, connectivity and width. There was an early stimulation of bone formation that was indicated by generation of thicker and interconnected trabeculae. However in caudal vertebrae, there were architectural changes in cancellous bone commencing with a significant increase in the trabecular separation. ‌‌ It was concluded that strengthens the cancellous component of the maternal skeleton possibly to counter increased load and to facilitate mineral mobilisation in maternal/neonate exchange during the subsequent lactation period.

  5. NCBI nr-aa BLAST: CBRC-GACU-03-0016 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available cilin precursor (Trabecular meshwork-induced glucocorticoid response protein) gb|AAC52051.1| trabecular meshwork... inducible glucocorticoid response protein [Homo sapiens] gb|AAC51725.1| trabecular meshwork-induced glu...dbj|BAA23531.1| myocilin [Homo sapiens] gb|AAC14264.1| myocilin [Homo sapiens] gb|AAH29261.1| Myocilin, trabecular meshwork... inducible glucocorticoid response [Homo sapiens] emb|CAD92590.2| myocilin, trabecular meshwork... inducible glucocorticoid response [Homo sapiens] gb|EAW90903.1| myocilin, trabecular meshwork

  6. Osteoarthritis Imaging by Quantification of Tibial Trabecular Bone

    DEFF Research Database (Denmark)

    Marques, Joselene

    The pathogenesis of osteoarthritis (OA) includes complex events in the whole joint. In this project, we combined machine-learning techniques in a texture analysis framework and evaluated it in a longitudinal study, where magnetic resonance images of knees were used to quantify the tibial trabecular...... bone in both a marker for OA diagnosis and another marker for prediction of tibial cartilage loss. By multiple-instance learning, we also investigated which region of the tibia provided the best prognosis for cartilage loss. The inferior part of the tibial bone was classified as the most relevant...

  7. An expression relating breaking stress and density of trabecular bone

    DEFF Research Database (Denmark)

    Rajapakse, C.S.; Thomsen, J.S.; Ortiz, J.S.E.

    2004-01-01

    Bone mineral density (BMD) is the principal diagnostic tool used in clinical settings to diagnose and monitor osteoporosis. Experimental studies on ex vivo bone samples from multiple skeletal locations have been used to propose that their breaking stress bears a power-law relationship to volumetric...... BMD, with a location-dependent index. We argue that a power-law cannot represent effects of trabecular removal, which is one of the leading causes of reduction in bone strength. A new expression, proposed on the basis of theoretical and numerical analysis of a mathematical model, is tested using...

  8. Juvenile Trabecular Ossifying Fibroma of the Maxilla: a Case Report

    Science.gov (United States)

    Aboujaoude, Samia; Aoun, Georges

    2016-01-01

    Introduction: Juvenile ossifying fibromas are uncommon benign tumors. Their aggressiveness added to their high tendency to recur, provoke real diagnostic and therapeutic challenges for the dental practitioner and make a postoperative follow-up over the years indispensable. Case report: In this report, we present a case of a seven-year-old girl presented with a swelling in the face at the upper right maxillary region. After clinical, radiological, and histopathological examinations the diagnosis of trabecular juvenile ossifying fibroma was made. The lesion was surgically excised and followed up for two years with no evidence of recurrence. PMID:28210024

  9. MR imaging and osteoporosis: fractal lacunarity analysis of trabecular bone.

    Science.gov (United States)

    Zaia, Annamaria; Eleonori, Roberta; Maponi, Pierluigi; Rossi, Roberto; Murri, Roberto

    2006-07-01

    We develop a method of magnetic resonance (MR) image analysis able to provide parameter(s) sensitive to bone microarchitecture changes in aging, and to osteoporosis onset and progression. The method has been built taking into account fractal properties of many anatomic and physiologic structures. Fractal lacunarity analysis has been used to determine relevant parameter(s) to differentiate among three types of trabecular bone structure (healthy young, healthy perimenopausal, and osteoporotic patients) from lumbar vertebra MR images. In particular, we propose to approximate the lacunarity function by a hyperbola model function that depends on three coefficients, alpha, beta, and gamma, and to compute these coefficients as the solution of a least squares problem. This triplet of coefficients provides a model function that better represents the variation of mass density of pixels in the image considered. Clinical application of this preliminary version of our method suggests that one of the three coefficients, beta, may represent a standard for the evaluation of trabecular bone architecture and a potentially useful parametric index for the early diagnosis of osteoporosis.

  10. Fractal-based image texture analysis of trabecular bone architecture.

    Science.gov (United States)

    Jiang, C; Pitt, R E; Bertram, J E; Aneshansley, D J

    1999-07-01

    Fractal-based image analysis methods are investigated to extract textural features related to the anisotropic structure of trabecular bone from the X-ray images of cubic bone specimens. Three methods are used to quantify image textural features: power spectrum, Minkowski dimension and mean intercept length. The global fractal dimension is used to describe the overall roughness of the image texture. The anisotropic features formed by the trabeculae are characterised by a fabric ellipse, whose orientation and eccentricity reflect the textural anisotropy of the image. Tests of these methods with synthetic images of known fractal dimension show that the Minkowski dimension provides a more accurate and consistent estimation of global fractal dimension. Tests on bone x-ray (eccentricity range 0.25-0.80) images indicate that the Minkowski dimension is more sensitive to the changes in textural orientation. The results suggest that the Minkowski dimension is a better measure for characterising trabecular bone anisotropy in the x-ray images of thick specimens.

  11. Hyalinizing trabecular tumor and papillary carcinoma of the thyroid

    Institute of Scientific and Technical Information of China (English)

    ZHU Hong; QI Ji-ping; WANG Ying-wei; SONG Yue-jia; ZHANG Zhi-yi

    2010-01-01

    Background Hyalinizing trabecular tumor (HTT) is a rare thyroid neoplasm, which shares some histologic features with thyroid papillary carcinoma (TPC). Clinically, it is frequently misdiagnosed as papillary carcinoma, even for some experienced pathologists. The aim of this study was to investigate whether HTT is variant of TPC or HTT is an independent entity of thyroid neoplasm.Methods The expression of CK19, galectin-3, HBME-1 and MIB-1 was detected by immunohistochemical staining in 12 cases of hyalinizing trabecular tumor and 20 cases of thyroid papillary carcinoma.Results Two of the 12 HTT samples were positive or focally positive for CK19. Four of the 12 samples of HTT presented positive to galectin-3; 3 were stained strongly and the other one was focally positive. None of the 12 samples of HTT was positive for HBME-1. Five in 12 HTT samples were stained in nucleus for MIB-1. Almost all the 20 cases of thyroid papillary carcinoma were intensely stained for CK19, galectin-3 and HBME-1. Fifteen in 20 cases of thyroid papillary carcinoma showed nuclear staining for MIB-1.Conclusions HTT is an independent thyroid neoplasm, not a variant of TPC. This study could help in the differential diagnosis of HTT from TPC. CK19, galectin-3 and HBME-1 are adequate to identify HTT and TPC, but MIB-1 does not play an important role in discrimination between HTT and TPC.

  12. Trabecular bone response to injectable calcium phosphate (Ca-P) cement.

    NARCIS (Netherlands)

    Ooms, E.M.; Wolke, J.G.C.; Waerden, J.P.C.M. van der; Jansen, J.A.

    2002-01-01

    The aim of this study was to investigate the physicochemical, biological, and handling properties of a new developed calcium phosphate (Ca-P) cement when implanted in trabecular bone. Ca-P cement consisting of a powder and a liquid phase was implanted as a paste into femoral trabecular bone of goats

  13. A potential mechanism for allometric trabecular bone scaling in terrestrial mammals.

    Science.gov (United States)

    Christen, Patrik; Ito, Keita; van Rietbergen, Bert

    2015-03-01

    Trabecular bone microstructural parameters, including trabecular thickness, spacing, and number, have been reported to scale with animal size with negative allometry, whereas bone volume fraction is animal size-invariant in terrestrial mammals. As for the majority of scaling patterns described in animals, its underlying mechanism is unknown. However, it has also been found that osteocyte density is inversely related to animal size, possibly adapted to metabolic rate, which shows a negative relationship as well. In addition, the signalling reach of osteocytes is limited by the extent of the lacuno-canalicular network, depending on trabecular dimensions and thus also on animal size. Here we propose animal size-dependent variations in osteocyte density and their signalling influence distance as a potential mechanism for negative allometric trabecular bone scaling in terrestrial mammals. Using an established and tested computational model of bone modelling and remodelling, we run simulations with different osteocyte densities and influence distances mimicking six terrestrial mammals covering a large range of body masses. Simulated trabecular structures revealed negative allometric scaling for trabecular thickness, spacing, and number, constant bone volume fraction, and bone turnover rates inversely related to animal size. These results are in agreement with previous observations supporting our proposal of osteocyte density and influence distance variation as a potential mechanism for negative allometric trabecular bone scaling in terrestrial mammals. The inverse relationship between bone turnover rates and animal size further indicates that trabecular bone scaling may be linked to metabolic rather than mechanical adaptations. © 2015 Anatomical Society.

  14. Pocket proteins critically regulate cell cycle exit of the trabecular myocardium and the ventricular conduction system

    Directory of Open Access Journals (Sweden)

    David S. Park

    2013-07-01

    During development, the ventricular conduction system (VCS arises from the trabecular or spongy myocardium. VCS and trabecular myocytes proliferate at a significantly slower rate than compact zone myocardial cells, establishing a transmural cell cycle gradient. The molecular determinants of VCS/trabecular myocyte cell cycle arrest are not known. Given the importance of pocket proteins (Rb, p107 and p130 in mediating G0/G1 arrest in many cell types, we examined the role of this gene family in regulating cell cycle exit of the trabecular myocardium and ventricular conduction system. Using a combinatorial knockout strategy, we found that graded loss of pocket proteins results in a spectrum of heart and lung defects. p107/p130 double knockout (dKO hearts manifest dysregulated proliferation within the compact myocardium and trabecular bases, while the remaining trabecular region cell cycle exits normally. Consequently, dKO hearts exhibit defective cardiac compaction, septal hyperplasia and biventricular outflow tract obstruction, while the VCS appears relatively normal. Loss of all three pocket proteins (3KO is necessary to completely disrupt the transmural cell cycle gradient. 3KO hearts exhibit massive overgrowth of the trabecular myocardium and ventricular conduction system, which leads to fetal heart failure and death. Hearts carrying a single pocket protein allele are able to maintain the transmural cell cycle gradient. These results demonstrate the exquisite sensitivity of trabecular and conduction myocytes to pocket protein function during ventricular chamber development.

  15. A new method to determine trabecular bone elastic properties and loading using micromechanical finite-element models

    NARCIS (Netherlands)

    R. van Rietbergen (Bert); H.H. Weinans (Harrie); R. Huiskes (Rik); A. Odgaard

    1995-01-01

    textabstractThe apparent mechanical behavior of trabecular bone depends on properties at the tissue or trabecular level. Many investigators have attempted to determine trabecular tissue properties and loading. However, accuracy and applicability of all methods reported are limited. The small size of

  16. A model of trabecular bone and an application to osteoporosis

    Science.gov (United States)

    Gunaratne, Gemunu H.; Mohanty, Kishore K.; Wimalawansa, Sunil J.

    2002-11-01

    Large bones consists of an outer compact shaft and an inner porous segment, known as the trabecular architecture (TA). The TA is the principal load carrier in bones from older adults, and the aim of therapeutic interventions is to preserve their strength. It is argued that forms for broad-based diagnostic tools for osteoporosis can be identified through an analysis of simple model systems. A model based on elastic networks is introduced, and shows that weak networks can only utilize a small fraction of themselves for stress transmission. This observation is used to argue that the ratio of linear response of a network to DC and AC strain can be used as a surrogate for bone strength. We discuss the possibility of using this measure to identify osteoporotic bone and to monitor the efficacy of therapy.

  17. A review of trabecular bone functional adaptation: what have we learned from trabecular analyses in extant hominoids and what can we apply to fossils?

    Science.gov (United States)

    Kivell, Tracy L

    2016-04-01

    Many of the unresolved debates in palaeoanthropology regarding evolution of particular locomotor or manipulative behaviours are founded in differing opinions about the functional significance of the preserved external fossil morphology. However, the plasticity of internal bone morphology, and particularly trabecular bone, allowing it to respond to mechanical loading during life means that it can reveal greater insight into how a bone or joint was used during an individual's lifetime. Analyses of trabecular bone have been commonplace for several decades in a human clinical context. In contrast, the study of trabecular bone as a method for reconstructing joint position, joint loading and ultimately behaviour in extant and fossil non-human primates is comparatively new. Since the initial 2D studies in the late 1970s and 3D analyses in the 1990 s, the utility of trabecular bone to reconstruct behaviour in primates has grown to incorporate experimental studies, expanded taxonomic samples and skeletal elements, and improved methodologies. However, this work, in conjunction with research on humans and non-primate mammals, has also revealed the substantial complexity inherent in making functional inferences from variation in trabecular architecture. This review addresses the current understanding of trabecular bone functional adaptation, how it has been applied to hominoids, as well as other primates and, ultimately, how this can be used to better interpret fossil hominoid and hominin morphology. Because the fossil record constrains us to interpreting function largely from bony morphology alone, and typically from isolated bones, analyses of trabecular structure, ideally in conjunction with that of cortical structure and external morphology, can offer the best resource for reconstructing behaviour in the past.

  18. Differences in Trabecular Microstructure Between Black and White Women Assessed by Individual Trabecular Segmentation Analysis of HR-pQCT Images.

    Science.gov (United States)

    Putman, Melissa S; Yu, Elaine W; Lin, David; Darakananda, Karin; Finkelstein, Joel S; Bouxsein, Mary L

    2017-05-01

    Black women have lower fracture risk compared with white women, which may be partly explained by improved volumetric bone mineral density (vBMD) and bone microarchitecture primarily within the cortical bone compartment. To determine if there are differences in trabecular microstructure, connectivity, and alignment according to race/ethnicity, we performed individual trabecular segmentation (ITS) analyses on high-resolution peripheral quantitative computed tomography (HR-pQCT) scans of the distal radius and tibia in 273 peri- and postmenopausal black (n = 100) and white (n = 173) women participating in the Study of Women's Health Across the Nation in Boston. Unadjusted analyses showed that black women had greater trabecular plate volume fraction, plate thickness, plate number density, and plate surface area along with greater axial alignment of trabeculae, whereas white women had greater trabecular rod tissue fraction (p < 0.05 for all). Adjustment for clinical covariates augmented these race/ethnicity-related differences in plates and rods, such that white women had greater trabecular rod number density and rod-rod connectivity, whereas black women continued to have superior plate structural characteristics and axial alignment (p < 0.05 for all). These differences remained significant after adjustment for hip BMD and trabecular vBMD. In conclusion, black women had more plate-like trabecular morphology and higher axial alignment of trabeculae, whereas white women had more rod-like trabeculae. These differences may contribute to the improved bone strength and lower fracture risk observed in black women. © 2016 American Society for Bone and Mineral Research. © 2016 American Society for Bone and Mineral Research.

  19. Heritability of lumbar trabecular bone mechanical properties in baboons.

    Science.gov (United States)

    Havill, L M; Allen, M R; Bredbenner, T L; Burr, D B; Nicolella, D P; Turner, C H; Warren, D M; Mahaney, M C

    2010-03-01

    Genetic effects on mechanical properties have been demonstrated in rodents, but not confirmed in primates. Our aim was to quantify the proportion of variation in vertebral trabecular bone mechanical properties that is due to the effects of genes. L3 vertebrae were collected from 110 females and 46 male baboons (6-32 years old) from a single extended pedigree. Cranio-caudally oriented trabecular bone cores were scanned with microCT then tested in monotonic compression to determine apparent ultimate stress, modulus, and toughness. Age and sex effects and heritability (h(2)) were assessed using maximum likelihood-based variance components methods. Additive effects of genes on residual trait variance were significant for ultimate stress (h(2)=0.58), toughness (h(2)=0.64), and BV/TV (h(2)=0.55). When BV/TV was accounted for, the residual variance in ultimate stress accounted for by the additive effects of genes was no longer significant. Toughness, however, showed evidence of a non-BV/TV-related genetic effect. Overall, maximum stress and modulus show strong genetic effects that are nearly entirely due to bone volume. Toughness shows strong genetic effects related to bone volume and shows additional genetic effects (accounting for 10% of the total trait variance) that are independent of bone volume. These results support continued use of bone volume as a focal trait to identify genes related to skeletal fragility, but also show that other focal traits related to toughness and variation in the organic component of bone matrix will enhance our ability to find additional genes that are particularly relevant to fatigue-related fractures.

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

    Energy Technology Data Exchange (ETDEWEB)

    Hamed, Elham [University of Illinois at Urbana-Champaign, Department of Mechanical Science and Engineering, 1206 West Green Street, Urbana, IL 61801 (United States); Novitskaya, Ekaterina, E-mail: eevdokim@ucsd.edu [University of California, San Diego, Department of Mechanical and Aerospace Engineering, Materials Science and Engineering Program, 9500 Gilman Dr., La Jolla, CA 92093 (United States); Li, Jun; Jasiuk, Iwona [University of Illinois at Urbana-Champaign, Department of Mechanical Science and Engineering, 1206 West Green Street, Urbana, IL 61801 (United States); McKittrick, Joanna [University of California, San Diego, Department of Mechanical and Aerospace Engineering, Materials Science and Engineering Program, 9500 Gilman Dr., La Jolla, CA 92093 (United States)

    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. - Highlights: • A multiscale model was used to predict the elastic moduli of trabecular bone. • Samples included demineralized, deproteinized and untreated bone. • The model portrays bone as a porous, interpenetrating two phase composite. • The experimental elastic moduli for trabecular bone fell between theoretical bounds.

  1. Efficacy of non-penetrating trabecular surgery for open angle glaucoma:a meta-analysis

    Institute of Scientific and Technical Information of China (English)

    程金伟; 马晓晔; 魏锐

    2004-01-01

    Background Non-penetrating trabecular surgery is a new filtrating surgery without opening in ternal trabecular structures. This study was to estimate the overall efficacy of non-penetrating trabecular surgery for open angle glaucoma.Methods The published articles selected for this study were obtained by a computerised Medline and China Biological Medicine Disk search of the literature and a manual search of the bibliographies of relevant articles. Articles meeting the inclusion criteria were reviewed systematically, and the reported data were aggregated using the statistical techniques of meta-analysis.Results A total of 37 articles were included in the meta-analysis. The pooled complete success rates of non-penetrating trabecular surgery with different techniques were: deep sclerectomy single, 69.7% (95% CI: 58.5%-81.0%); deep sclerectomy with collagen implant, 59.4% (95% CI: 47.0%-71.8%); deep sclerectomy with reticulated hyaluronic acid implant, 71.1% (95% CI: 56.8%-85.3%); and viscocanalostomy, 72.0% (95% CI: 57.6%-86.4%). The overall weighted complete success rate of non-penetrating trabecular surgery was 67.8% (95% CI: 61.4%-74.3%).Conclusions Non-penetrating trabecular surgery is the best available therapy method for medically uncontrolled open angle glaucoma with a complete success rate of over 60%. But the different techniques cannot belie the complete success rate of non-penetrating trabecular surgery.

  2. Preliminary radiological assessment of age-related change in the trabecular structure of the human os pubis.

    Science.gov (United States)

    Wade, Andrew; Nelson, Andrew; Garvin, Greg; Holdsworth, David W

    2011-03-01

    This preliminary study examines correlations between age-at-death and changes in the trabecular architecture of the human os pubis, utilizing continuous, quantitative data from plain film radiography, computed tomography (CT), and micro-CT scans of 65 male innominates. Radiography provides nondestructive options for assessment, digital preservation, and presentation of human skeletal remains; important for forensic and culturally sensitive archaeological materials, which must remain unmodified for opposing experts, future researchers, or repatriation and reburial. Radiographic techniques permit analysis of remains that cannot be disarticulated (e.g., religious proscription, mummies), and trabecular measures provide data where traditional surface indicators are obscured or damaged. Potentially, robust predictive models derived herein achieve R-values of 0.522, 0.447, and 0.731, respectively. Further testing of these methods may validate these techniques as further lines of evidence in age estimation, with the potential to improve on the accuracy of traditional qualitative techniques by providing quantitative, continuous variables in predicting skeletal age-at-death.

  3. Trabecular bone structure correlates with hand posture and use in hominoids.

    Science.gov (United States)

    Tsegai, Zewdi J; Kivell, Tracy L; Gross, Thomas; Nguyen, N Huynh; Pahr, Dieter H; Smaers, Jeroen B; Skinner, Matthew M

    2013-01-01

    Bone is capable of adapting during life in response to stress. Therefore, variation in locomotor and manipulative behaviours across extant hominoids may be reflected in differences in trabecular bone structure. The hand is a promising region for trabecular analysis, as it is the direct contact between the individual and the environment and joint positions at peak loading vary amongst extant hominoids. Building upon traditional volume of interest-based analyses, we apply a whole-epiphysis analytical approach using high-resolution microtomographic scans of the hominoid third metacarpal to investigate whether trabecular structure reflects differences in hand posture and loading in knuckle-walking (Gorilla, Pan), suspensory (Pongo, Hylobates and Symphalangus) and manipulative (Homo) taxa. Additionally, a comparative phylogenetic method was used to analyse rates of evolutionary changes in trabecular parameters. Results demonstrate that trabecular bone volume distribution and regions of greatest stiffness (i.e., Young's modulus) correspond with predicted loading of the hand in each behavioural category. In suspensory and manipulative taxa, regions of high bone volume and greatest stiffness are concentrated on the palmar or distopalmar regions of the metacarpal head, whereas knuckle-walking taxa show greater bone volume and stiffness throughout the head, and particularly in the dorsal region; patterns that correspond with the highest predicted joint reaction forces. Trabecular structure in knuckle-walking taxa is characterised by high bone volume fraction and a high degree of anisotropy in contrast to the suspensory brachiators. Humans, in which the hand is used primarily for manipulation, have a low bone volume fraction and a variable degree of anisotropy. Finally, when trabecular parameters are mapped onto a molecular-based phylogeny, we show that the rates of change in trabecular structure vary across the hominoid clade. Our results support a link between inferred

  4. Trabecular bone structure correlates with hand posture and use in hominoids.

    Directory of Open Access Journals (Sweden)

    Zewdi J Tsegai

    Full Text Available Bone is capable of adapting during life in response to stress. Therefore, variation in locomotor and manipulative behaviours across extant hominoids may be reflected in differences in trabecular bone structure. The hand is a promising region for trabecular analysis, as it is the direct contact between the individual and the environment and joint positions at peak loading vary amongst extant hominoids. Building upon traditional volume of interest-based analyses, we apply a whole-epiphysis analytical approach using high-resolution microtomographic scans of the hominoid third metacarpal to investigate whether trabecular structure reflects differences in hand posture and loading in knuckle-walking (Gorilla, Pan, suspensory (Pongo, Hylobates and Symphalangus and manipulative (Homo taxa. Additionally, a comparative phylogenetic method was used to analyse rates of evolutionary changes in trabecular parameters. Results demonstrate that trabecular bone volume distribution and regions of greatest stiffness (i.e., Young's modulus correspond with predicted loading of the hand in each behavioural category. In suspensory and manipulative taxa, regions of high bone volume and greatest stiffness are concentrated on the palmar or distopalmar regions of the metacarpal head, whereas knuckle-walking taxa show greater bone volume and stiffness throughout the head, and particularly in the dorsal region; patterns that correspond with the highest predicted joint reaction forces. Trabecular structure in knuckle-walking taxa is characterised by high bone volume fraction and a high degree of anisotropy in contrast to the suspensory brachiators. Humans, in which the hand is used primarily for manipulation, have a low bone volume fraction and a variable degree of anisotropy. Finally, when trabecular parameters are mapped onto a molecular-based phylogeny, we show that the rates of change in trabecular structure vary across the hominoid clade. Our results support a link

  5. Parallel plate model for trabecular bone exhibits volume fraction-dependant bias

    DEFF Research Database (Denmark)

    Day, J; Ding, Ming; Odgaard, A;

    2000-01-01

    Unbiased stereological methods were used in conjunction with microcomputed tomographic (micro-CT) scans of human and animal bone to investigate errors created when the parallel plate model was used to calculate morphometric parameters. Bone samples were obtained from the human proximal tibia......, canine distal femur, rat tail, and pig spine and scanned in a micro-CT scanner. Trabecular thickness, trabecular spacing, and trabecular number were calculated using the parallel plate model. Direct thickness, and spacing and connectivity density were calculated using unbiased three-dimensional methods...

  6. 嘌呤受体P2X7在人眼小梁网细胞上的表达及分布%Expression and distribution of purinergic receptor P2X7 in human trabecular meshwork cells

    Institute of Scientific and Technical Information of China (English)

    祝芸芸; 左炜; 王恒; 张秀兰

    2015-01-01

    目的 探讨嘌呤受体P2X7在体外培养正常人眼小梁网细胞上的表达及分布.方法 体外培养、鉴定正常人眼小梁网细胞,利用RT-PCR、Western-blot和免疫荧光法分别检测正常人眼小梁网细胞上P2X7受体mRNA和蛋白的表达情况及受体蛋白的主要分布部位.结果 光镜下观察原代培养的细胞具有人眼小梁网细胞的典型形态;免疫组织化学方法检测结果表明,培养的细胞纤维连接蛋白、层粘连蛋白、神经元特异性烯醇化酶及波形蛋白染色阳性,第Ⅷ因子染色阴性,鉴定为人眼小梁网细胞;RT-PCR扩增到了P2X7mRNA 152 bp大小的基因片段,Western-blot得到了相对分子质量约为74 000的P2X7的蛋白条带,免疫荧光法证实P2X7受体在小梁网细胞膜、细胞质及细胞核内均有广泛分布.结论 人眼小梁网细胞上有P2X7受体表达,其在细胞内分布广泛.

  7. Effect of micro-computed tomography voxel size and segmentation method on trabecular bone microstructure measures in mice.

    Science.gov (United States)

    Christiansen, Blaine A

    2016-12-01

    Micro-computed tomography (μCT) is currently the gold standard for determining trabecular bone microstructure in small animal models. Numerous parameters associated with scanning and evaluation of μCT scans can strongly affect morphologic results obtained from bone samples. However, the effect of these parameters on specific trabecular bone outcomes is not well understood. This study investigated the effect of μCT scanning with nominal voxel sizes between 6-30 μm on trabecular bone outcomes quantified in mouse vertebral body trabecular bone. Additionally, two methods for determining a global segmentation threshold were compared: based on qualitative assessment of 2D images, or based on quantitative assessment of image histograms. It was found that nominal voxel size had a strong effect on several commonly reported trabecular bone parameters, in particular connectivity density, trabecular thickness, and bone tissue mineral density. Additionally, the two segmentation methods provided similar trabecular bone outcomes for scans with small nominal voxel sizes, but considerably different outcomes for scans with larger voxel sizes. The Qualitatively Selected segmentation method more consistently estimated trabecular bone volume fraction (BV/TV) and trabecular thickness across different voxel sizes, but the Histogram segmentation method more consistently estimated trabecular number, trabecular separation, and structure model index. Altogether, these results suggest that high-resolution scans be used whenever possible to provide the most accurate estimation of trabecular bone microstructure, and that the limitations of accurately determining trabecular bone outcomes should be considered when selecting scan parameters and making conclusions about inter-group variance or between-group differences in studies of trabecular bone microstructure in small animals.

  8. Trabecular bone adaptation to low-magnitude high-frequency loading in microgravity.

    Science.gov (United States)

    Torcasio, Antonia; Jähn, Katharina; Van Guyse, Maarten; Spaepen, Pieter; Tami, Andrea E; Vander Sloten, Jos; Stoddart, Martin J; van Lenthe, G Harry

    2014-01-01

    Exposure to microgravity causes loss of lower body bone mass in some astronauts. Low-magnitude high-frequency loading can stimulate bone formation on earth. Here we hypothesized that low-magnitude high-frequency loading will also stimulate bone formation under microgravity conditions. Two groups of six bovine cancellous bone explants were cultured at microgravity on a Russian Foton-M3 spacecraft and were either loaded dynamically using a sinusoidal curve or experienced only a static load. Comparable reference groups were investigated at normal gravity. Bone structure was assessed by histology, and mechanical competence was quantified using μCT and FE modelling; bone remodelling was assessed by fluorescent labelling and secreted bone turnover markers. Statistical analyses on morphometric parameters and apparent stiffness did not reveal significant differences between the treatment groups. The release of bone formation marker from the groups cultured at normal gravity increased significantly from the first to the second week of the experiment by 90.4% and 82.5% in response to static and dynamic loading, respectively. Bone resorption markers decreased significantly for the groups cultured at microgravity by 7.5% and 8.0% in response to static and dynamic loading, respectively. We found low strain magnitudes to drive bone turnover when applied at high frequency, and this to be valid at normal as well as at microgravity. In conclusion, we found the effect of mechanical loading on trabecular bone to be regulated mainly by an increase of bone formation at normal gravity and by a decrease in bone resorption at microgravity. Additional studies with extended experimental time and increased samples number appear necessary for a further understanding of the anabolic potential of dynamic loading on bone quality and mechanical competence.

  9. Trabecular bone adaptation to low-magnitude high-frequency loading in microgravity.

    Directory of Open Access Journals (Sweden)

    Antonia Torcasio

    Full Text Available Exposure to microgravity causes loss of lower body bone mass in some astronauts. Low-magnitude high-frequency loading can stimulate bone formation on earth. Here we hypothesized that low-magnitude high-frequency loading will also stimulate bone formation under microgravity conditions. Two groups of six bovine cancellous bone explants were cultured at microgravity on a Russian Foton-M3 spacecraft and were either loaded dynamically using a sinusoidal curve or experienced only a static load. Comparable reference groups were investigated at normal gravity. Bone structure was assessed by histology, and mechanical competence was quantified using μCT and FE modelling; bone remodelling was assessed by fluorescent labelling and secreted bone turnover markers. Statistical analyses on morphometric parameters and apparent stiffness did not reveal significant differences between the treatment groups. The release of bone formation marker from the groups cultured at normal gravity increased significantly from the first to the second week of the experiment by 90.4% and 82.5% in response to static and dynamic loading, respectively. Bone resorption markers decreased significantly for the groups cultured at microgravity by 7.5% and 8.0% in response to static and dynamic loading, respectively. We found low strain magnitudes to drive bone turnover when applied at high frequency, and this to be valid at normal as well as at microgravity. In conclusion, we found the effect of mechanical loading on trabecular bone to be regulated mainly by an increase of bone formation at normal gravity and by a decrease in bone resorption at microgravity. Additional studies with extended experimental time and increased samples number appear necessary for a further understanding of the anabolic potential of dynamic loading on bone quality and mechanical competence.

  10. Evaluation of machining methods for trabecular metal implants in a rabbit intramedullary osseointegration model.

    Science.gov (United States)

    Deglurkar, Mukund; Davy, Dwight T; Stewart, Matthew; Goldberg, Victor M; Welter, Jean F

    2007-02-01

    Implant success is dependent in part on the interaction of the implant with the surrounding tissues. Porous tantalum implants (Trabecular Metal, TM) have been shown to have excellent osseointegration. Machining this material to complex shapes with close tolerances is difficult because of its open structure and the ductile nature of metallic tantalum. Conventional machining results in occlusion of most of the surface porosity by the smearing of soft metal. This study compared TM samples finished by three processing techniques: conventional machining, electrical discharge machining, and nonmachined, "as-prepared." The TM samples were studied in a rabbit distal femoral intramedullary osseointegration model and in cell culture. We assessed the effects of these machining methods at 4, 8, and 12 weeks after implant placement. The finishing technique had a profound effect on the physical presentation of the implant interface: conventional machining reduced surface porosity to 30% compared to bulk porosities in the 70% range. Bone ongrowth was similar in all groups, while bone ingrowth was significantly greater in the nonmachined samples. The resulting mechanical properties of the bone implant-interface were similar in all three groups, with only interface stiffness and interface shear modulus being significantly higher in the machined samples.

  11. Microsurgical anatomy of the arachnoidal trabecular membranes and cisterns at the level of the tentorium.

    Science.gov (United States)

    Vinas, F C; Dujovny, M; Fandino, R; Chavez, V

    1996-08-01

    A clear and thorough understanding of the neuroanatomical structures of the subarachnoid cisterns is important because they provide natural pathways to intracranial arteries, veins, and nerves during microvascular procedures without disturbing surrounding important brain structures. Using a surgical microscope, we examined the microsurgical anatomy of the trabecular membranes and subarachnoid cisterns in 20 adult cadaver brains. The brains were immersed in Ringer's solution and air was injected into the subarachnoid cisterns while the brains remained submerged in solution. We identified seven trabecular membranes that limit six cisterns. We specifically looked at the anatomical relationship between the trabecular membranes and cisterns and their corresponding vessels and cranial nerves. The cistern divisions and the dispositions of trabecular membranes were closely related to the vascular division patterns of the principal brain arteries.

  12. Bisphosphonate treatment affects trabecular bone apparent modulus through micro-architecture rather than matrix properties

    DEFF Research Database (Denmark)

    Ding, Ming

    2004-01-01

    and trabecular architecture independently. Conventional histomorphometry and microdamage data were obtained from the second and third lumbar vertebrae of the same dogs [Bone 28 (2001) 524]. Bisphosphonate treatment resulted in an increased apparent Young's modulus, decreased bone turnover, increased calcified......Bisphosphonates are emerging as an important treatment for osteoporosis. But whether the reduced fracture risk associated with bisphosphonate treatment is due to increased bone mass, improved trabecular architecture and/or increased secondary mineralization of the calcified matrix remains unclear....... We examined the effects of bisphosphonates on both the trabecular architecture and matrix properties of canine trabecular bone. Thirty-six beagles were divided into a control group and two treatment groups, one receiving risedronate and the other alendronate at 5-6 times the clinical dose...

  13. Characterization of drug-release kinetics in trabecular bone from titania nanotube implants

    Directory of Open Access Journals (Sweden)

    Aw MS

    2012-09-01

    vivo showed a consistent gradual release of model drug from the TNT–Ti implants, with a characteristic three-dimensional distribution into the surrounding bone, over a period of 5 days. The parameters including the flow rate of bone culture medium, differences in trabecular microarchitecture between bone samples, and mechanical loading were found to have the most significant influence on drug distribution in the bone.Conclusion: These results demonstrate the utility of the Zetos™ system for ex vivo drug-release studies in bone, which can be applied to optimize the delivery of specific therapies and to assist in the design of new drug delivery systems. This method has the potential to provide new knowledge to understand drug distribution in the bone environment and to considerably improve existing technologies for local administration in bone, including solving some critical problems in bone therapy and orthopedic implants.Keywords: local drug delivery, Zetos bone bioreactor, drug-releasing implant, drug diffusion

  14. Preliminary study of slow and fast ultrasonic waves using MR images of trabecular bone phantom

    Energy Technology Data Exchange (ETDEWEB)

    Solis-Najera, S. E., E-mail: solisnajera@ciencias.unam.mx, E-mail: angel.perez@ciencias.unam.mx, E-mail: lucia.medina@ciencias.unam.mx; Neria-Pérez, J. A., E-mail: solisnajera@ciencias.unam.mx, E-mail: angel.perez@ciencias.unam.mx, E-mail: lucia.medina@ciencias.unam.mx; Medina, L., E-mail: solisnajera@ciencias.unam.mx, E-mail: angel.perez@ciencias.unam.mx, E-mail: lucia.medina@ciencias.unam.mx [Facultad de Ciencias, Universidad Nacional Autónoma de México, México, DF 04510 (Mexico); Garipov, R., E-mail: ruslan.garipov@mrsolutions.co.uk [MR Solutions Ltd, Surrey (United Kingdom); Rodríguez, A. O., E-mail: arog@xanum.uam.mx [Departamento Ingeniería Eléctrica, Universidad Autónoma Metropolitana Iztapalapa, México, DF 09340 (Mexico)

    2014-11-07

    Cancellous bone is a complex tissue that performs physiological and biomechanical functions in all vertebrates. It is made up of trabeculae that, from a simplified structural viewpoint, can be considered as plates and beams in a hyperstatic structure that change with time leading to osteoporosis. Several methods has been developed to study the trabecular bone microstructure among them is the Biot’s model which predicts the existence of two longitudinal waves in porous media; the slow and the fast waves, that can be related to porosity of the media. This paper is focused on the experimental detection of the two Biot’s waves of a trabecular bone phantom, consisting of a trabecular network of inorganic hydroxyapatite. Experimental measurements of both waves were performed using through transmission ultrasound. Results had shown clearly that the propagation of two waves propagation is transversal to the trabecular alignment. Otherwise the waves are overlapped and a single wave seems to be propagated. To validate these results, magnetic resonance images were acquired to assess the trabecular direction, and to assure that the pulses correspond to the slow and fast waves. This approach offers a methodology for non-invasive studies of trabecular bones.

  15. Computational study of Wolff's law with trabecular architecture in the human proximal femur using topology optimization.

    Science.gov (United States)

    Jang, In Gwun; Kim, Il Yong

    2008-08-07

    In the field of bone adaptation, it is believed that the morphology of bone is affected by its mechanical loads, and bone has self-optimizing capability; this phenomenon is well known as Wolff's law of the transformation of bone. In this paper, we simulated trabecular bone adaptation in the human proximal femur using topology optimization and quantitatively investigated the validity of Wolff's law. Topology optimization iteratively distributes material in a design domain producing optimal layout or configuration, and it has been widely and successfully used in many engineering fields. We used a two-dimensional micro-FE model with 50 microm pixel resolution to represent the full trabecular architecture in the proximal femur, and performed topology optimization to study the trabecular morphological changes under three loading cases in daily activities. The simulation results were compared to the actual trabecular architecture in previous experimental studies. We discovered that there are strong similarities in trabecular patterns between the computational results and observed data in the literature. The results showed that the strain energy distribution of the trabecular architecture became more uniform during the optimization; from the viewpoint of structural topology optimization, this bone morphology may be considered as an optimal structure. We also showed that the non-orthogonal intersections were constructed to support daily activity loadings in the sense of optimization, as opposed to Wolff's drawing.

  16. Evaluation of trabecular bone patterns on dental radiographic images: influence of cortical bone

    Science.gov (United States)

    Amouriq, Yves; Evenou, Pierre; Arlicot, Aurore; Normand, Nicolas; Layrolle, Pierre; Weiss, Pierre; Guédon, Jean-Pierre

    2010-03-01

    For some authors trabecular bone is highly visible in intraoral radiographs. For other authors, the observed intrabony trabecular pattern is a representation of only the endosteal surface of cortical bone, not of intermedullary striae. The purpose of this preliminary study was to investigate the true anatomical structures that are visible in routine dental radiographs and classically denoted trabecular bone. This is a major point for bone texture analysis on radiographs. Computed radiography (CR) images of dog mandible section in molar region were compared with simulations calculated from high-resolution micro-CT volumes. Calculated simulations were obtained using the Mojette Transform. By digitally editing the CT volume, the simulations were separated into trabecular and cortical components into a region of interest. Different images were compared and correlated, some bone micro-architecture parameters calculated. A high correlation was found between computed radiographs and calculated simulations from micro-CT. The Mojette transform was successful to obtain high quality images. Cortical bone did not contribute to change in a major way simulated images. These first results imply that intrabony trabecular pattern observed on radiographs can not only be a representation of the cortical bone endosteal surface and that trabecular bone is highly visible in intraoral radiographs.

  17. Utility of trabecular bone score in the evaluation of osteoporosis.

    Science.gov (United States)

    Martineau, Patrick; Silva, Barbara C; Leslie, William D

    2017-08-28

    Trabecular bone score (TBS) is a lumbar spine dual-energy absorptiometry texture index which provides information on skeletal quality partially independent of bone mineral density (BMD). A body of work has emerged demonstrating the relationship between TBS and fracture risk, with lower TBS values associated with increased risk for osteoporotic fracture in postmenopausal women and older men. TBS is derived from standard DXA images; however, the information provided by TBS is complementary to that provided by BMD. In this article, we review the current state of TBS and its evolving role in the assessment and management of osteoporosis, with particular emphasis on the literature of the previous year. TBS-adjusted The Fracture Risk Assessment tool (FRAX) probabilities enhance fracture risk prediction compared with conventional FRAX predictions. TBS has been found to better categorize fracture risk and assists in FRAX-based treatment decisions, particularly for patients close to an intervention threshold. However, change in lumbar spine TBS while undergoing antiresorptive treatment is not a useful indicator of antifracture effect. Lumbar spine TBS is a recently developed image-based software technique for skeletal assessment, complementary to conventional BMD, which has been shown to be clinically useful as a fracture risk prediction tool.

  18. Changes of trabecular bone under control of biologically mechanical mechanism

    Science.gov (United States)

    Wang, C.; Zhang, C. Q.; Dong, X.; Wu, H.

    2008-10-01

    In this study, a biological process of bone remodeling was considered as a closed loop feedback control system, which enables bone to optimize and renew itself over a lifetime. A novel idea of combining strain-adaptive and damage-induced remodeling algorithms at Basic Multicellular Unit (BMU) level was introduced. In order to make the outcomes get closer to clinical observation, the stochastic occurrence of microdamage was involved and a hypothesis that remodeling activation probability is related to the value of damage rate was assumed. Integrated with Finite Element Analysis (FEA), the changes of trabecular bone in morphology and material properties were simulated in the course of five years. The results suggest that deterioration and anisotropy of trabecluar bone are inevitable with natural aging, and that compression rather than tension can be applied to strengthen the ability of resistance to fracture. This investigation helps to gain more insight the mechanism of bone loss and identify improved treatment and prevention for osteoporosis or stress fracture.

  19. A nonlocal constitutive model for trabecular bone softening in compression.

    Science.gov (United States)

    Charlebois, Mathieu; Jirásek, Milan; Zysset, Philippe K

    2010-10-01

    Using the three-dimensional morphological data provided by computed tomography, finite element (FE) models can be generated and used to compute the stiffness and strength of whole bones. Three-dimensional constitutive laws capturing the main features of bone mechanical behavior can be developed and implemented into FE software to enable simulations on complex bone structures. For this purpose, a constitutive law is proposed, which captures the compressive behavior of trabecular bone as a porous material with accumulation of irreversible strain and loss of stiffness beyond its yield point and softening beyond its ultimate point. To account for these features, a constitutive law based on damage coupled with hardening anisotropic elastoplasticity is formulated using density and fabric-based tensors. To prevent mesh dependence of the solution, a nonlocal averaging technique is adopted. The law has been implemented into a FE software and some simple simulations are first presented to illustrate its behavior. Finally, examples dealing with compression of vertebral bodies clearly show the impact of softening on the localization of the inelastic process.

  20. Parameter Estimation in Ultrasonic Measurements on Trabecular Bone

    Science.gov (United States)

    Marutyan, Karen R.; Anderson, Christian C.; Wear, Keith A.; Holland, Mark R.; Miller, James G.; Bretthorst, G. Larry

    2007-11-01

    Ultrasonic tissue characterization has shown promise for clinical diagnosis of diseased bone (e.g., osteoporosis) by establishing correlations between bone ultrasonic characteristics and the state of disease. Porous (trabecular) bone supports propagation of two compressional modes, a fast wave and a slow wave, each of which is characterized by an approximately linear-with-frequency attenuation coefficient and monotonically increasing with frequency phase velocity. Only a single wave, however, is generally apparent in the received signals. The ultrasonic parameters that govern propagation of this single wave appear to be causally inconsistent [1]. Specifically, the attenuation coefficient rises approximately linearly with frequency, but the phase velocity exhibits a decrease with frequency. These inconsistent results are obtained when the data are analyzed under the assumption that the received signal is composed of one wave. The inconsistency disappears if the data are analyzed under the assumption that the signal is composed of superposed fast and slow waves. In the current investigation, Bayesian probability theory is applied to estimate the ultrasonic characteristics underlying the propagation of the fast and slow wave from computer simulations. Our motivation is the assumption that identifying the intrinsic material properties of bone will provide more reliable estimates of bone quality and fracture risk than the apparent properties derived by analyzing the data using a one-mode model.

  1. 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

  2. cultural

    Directory of Open Access Journals (Sweden)

    Irene Kreutz

    2006-01-01

    Full Text Available Es un estudio cualitativo que adoptó como referencial teorico-motodológico la antropología y la etnografía. Presenta las experiencias vivenciadas por mujeres de una comunidad en el proceso salud-enfermedad, con el objetivo de comprender los determinantes sócio-culturales e históricos de las prácticas de prevención y tratamiento adoptados por el grupo cultural por medio de la entrevista semi-estructurada. Los temas que emergieron fueron: la relación entre la alimentación y lo proceso salud-enfermedad, las relaciones con el sistema de salud oficial y el proceso salud-enfermedad y lo sobrenatural. Los dados revelaron que los moradores de la comunidad investigada tienen un modo particular de explicar sus procedimientos terapéuticos. Consideramos que es papel de los profesionales de la salud en sus prácticas, la adopción de abordajes o enfoques que consideren al individuo en su dimensión sócio-cultural e histórica, considerando la enorme diversidad cultural en nuestro país.

  3. The vertebral trabecular model revisited: magnetic field distribution in the vicinity of osseous disconnections

    Science.gov (United States)

    Kraiger, Markus; Schnizer, Bernhard; Stollberger, Rudolf

    2016-12-01

    In the current paper a vertebral bone model is introduced that can be used for studying trabecular thinning and the formation of trabecular disconnections. Magnetostatic simulations are applied in MR-osteodensitometry to deduce the quality of trabecular bone from experimentally obtained susceptibility effects. The course of trabecular bone loss, which results in distinct interruptions and consequently severe mechanical impairment, is not assessable in the majority of such applied models. In the novel approach introduced here, analytical solutions of prolate ellipsoids were used to compute the disturbed magnetic fields within the proposed 3D model. The performed simulations focused on two variants of the vertebral model: an intact model and a pathological model accounting for microdamage. For both variants, magnetic resonance spectra were simulated for different bone volume fractions. Subsequently, resonance signals were obtained from the Fourier transform of the distribution with respect to time. The resonance time courses were analyzed through common signal models to estimate the relaxation time {{T}\\prime}2 of the corresponding free induction decay. Detailed computations revealed the significant contribution of the microdamage to the susceptibility effect. Further, when comparing the line broadening effect between the intact and disrupted models a contradictory outcome was found. The damaged osseous network for the lower bone fraction resulted in faster decay of the transverse magnetization. In conclusion, a significant contribution of trabecular disconnections to the susceptibility effect has been shown by the presented model. Future dedicated MRI experiments can explore the use of this effect to assess the integrity of cancellous bone.

  4. Effect of vitamin K2 on three-dimensional trabecular microarchitecture in ovariectomized rats.

    Science.gov (United States)

    Mawatari, T; Miura, H; Higaki, H; Moro-Oka, T; Kurata, K; Murakami, T; Iwamoto, Y

    2000-09-01

    Menatetrenone, a vitamin K2 with four isoprene units, has been reported to improve osteoporotic bone loss. The purpose of this investigation was to clarify the effect of menatetrenone on the three-dimensional (3D) trabecular microarchitecture in ovariectomized (OVX) rats by using microcomputed tomography (MCT). Forty-two 13-week-old female rats were used and divided into four groups: the OVX (OVX + MK-4) group treated with menatetrenone, the (OVX untreated) group, the sham-operated (Sham + MK-4) group treated with menatetrenone, and the sham-operated group not treated with menatetrenone (Sham untreated) group. OVX rats were fed a calcium-deficient diet. Menatetrenone treatment was begun just after the ovariectomy, and the mean menatetrenone oral intake over the 8-week period was adjusted to 30 mg/kg BW per day. The proximal metaphyseal region of the right tibia was evaluated by dual X-ray absorptiometry (DXA) and MCT. A parametric analysis of the reconstructed trabecular volume was carried out using bone volume fractions, the fractal dimension calculated by the 3D box-counting method, and the connectivity density as determined by topological analysis. Menatetrenone significantly increased the trabecular bone volume, fractal dimension, and connectivity in the OVX + MK-4 group compared with the OVX-untreated group (p ovariectomy. Despite this apparent protection, it remains unknown whether it is possible to reestablish trabecular connectivity if therapeutic intervention occurs after the trabecular connectivity has been lost.

  5. HYALINIZING TRABECULAR ADENOMA FEIGNING PAPILLARY CARCINOMA THYROID: CASE REPORT WITH REVIEW OF LITERATURE

    Directory of Open Access Journals (Sweden)

    Kandukuri Mahesh

    2014-05-01

    Full Text Available Hyalinizing Trabecular Adenoma (HTA of the thyroid is a rare neoplasm that was first described by Carney in 1987. It is a tumor of follicular derivation with peculiar nuclear, architectural, histochemical, and immunohistochemical features. We report a case of Hyalinizing trabecular adenoma in a 36-year-old woman with enlarged thyroid lobe. Ultrasonographic features and fine needle aspiration cytology (FNAC of the enlarged thyroid was performed and the diagnosis given was Papillary carcinoma of the thyroid. The patient underwent total thyroidectomy, with a histopathological diagnosis of hyalinizing trabecular Adenoma (HTA. We present this case in view of its rarity and to discuss the clinical and diagnostic approach, including the role of FNAC, and the pathologic features of HTA with special reference to the possible differential diagnosis and also review of literature. Although rare cases of malignant Hyalinizing trabecular adenoma (HTA have been documented, this tumor should be considered a benign neoplasm or at most, a neoplasm of extremely low malignant potential, however invasion of the capsule should be considered on histopathology. An awareness of hyalinizing trabecular adenomas and their characteristic features is valuable for their recognition and management as well as for the possible prevention of over diagnosis and over treatment for benign disease

  6. Independent scattering model and velocity dispersion in trabecular bone: comparison with a multiple scattering model.

    Science.gov (United States)

    Haïat, G; Naili, S

    2011-02-01

    Speed of sound measurements are used clinically to assess bone strength. Trabecular bone is an attenuating composite material in which negative values of velocity dispersion have been measured; this behavior remaining poorly explained physically. The aim of this work is to describe the ultrasonic propagation in trabecular bone modeled by infinite cylinders immersed in a saturating matrix and to derive the physical determinants of velocity dispersion. An original homogenization model accounting for the coupling of independent scattering and absorption phenomena allows the computation of phase velocity and of dispersion while varying bone properties. The first step of the model consists in the computation of the attenuation coefficient at all frequencies. The second step of the model corresponds to the application of the general Kramers-Krönig relationship to derive the frequency dependence of phase velocity. The model predicts negative values of velocity dispersion in agreement with experimental results obtained in phantoms mimicking trabecular bone. In trabecular bone, only negative values of velocity dispersion are predicted by the model, which span within the range of values measured experimentally. However, the comparison of the present results with results obtained in Haiat et al. (J Acoust Soc Am 124:4047-4058, 2008) assuming multiple scattering indicates that accounting for multiple scattering phenomena leads to a better prediction of velocity dispersion in trabecular bone.

  7. Bisphosphonate treatment affects trabecular bone apparent modulus through micro-architecture rather than matrix properties.

    Science.gov (United States)

    Day, J S; Ding, M; Bednarz, P; van der Linden, J C; Mashiba, T; Hirano, T; Johnston, C C; Burr, D B; Hvid, I; Sumner, D R; Weinans, H

    2004-05-01

    Bisphosphonates are emerging as an important treatment for osteoporosis. But whether the reduced fracture risk associated with bisphosphonate treatment is due to increased bone mass, improved trabecular architecture and/or increased secondary mineralization of the calcified matrix remains unclear. We examined the effects of bisphosphonates on both the trabecular architecture and matrix properties of canine trabecular bone. Thirty-six beagles were divided into a control group and two treatment groups, one receiving risedronate and the other alendronate at 5-6 times the clinical dose for osteoporosis treatment. After one year, the dogs were killed, and samples from the first lumbar vertebrae were examined using a combination of micro-computed tomography, finite element modeling, and mechanical testing. By combining these methods, we examined the treatment effects on the calcified matrix and trabecular architecture independently. Conventional histomorphometry and microdamage data were obtained from the second and third lumbar vertebrae of the same dogs [Bone 28 (2001) 524]. Bisphosphonate treatment resulted in an increased apparent Young's modulus, decreased bone turnover, increased calcified matrix density, and increased microdamage. We could not detect any change in the effective Young's modulus of the calcified matrix in the bisphosphonate treated groups. The observed increase in apparent Young's modulus was due to increased bone mass and altered trabecular architecture rather than changes in the calcified matrix modulus. We hypothesize that the expected increase in the Young's modulus of the calcified matrix due to the increased calcified matrix density was counteracted by the accumulation of microdamage.

  8. Mesenchymal stem cell proliferation and differentiation on load-bearing trabecular Nitinol scaffolds.

    Science.gov (United States)

    Gotman, Irena; Ben-David, Dror; Unger, Ronald E; Böse, Thomas; Gutmanas, Elazar Y; Kirkpatrick, C James

    2013-09-01

    Bone tissue regeneration in load-bearing regions of the body requires high-strength porous scaffolds capable of supporting angiogenesis and osteogenesis. 70% porous Nitinol (NiTi) scaffolds with a regular 3-D architecture resembling trabecular bone were produced from Ni foams using an original reactive vapor infiltration technique. The "trabecular Nitinol" scaffolds possessed a high compressive strength of 79 MPa and high permeability of 6.9×10(-6) cm2. The scaffolds were further modified to produce a near Ni-free surface layer and evaluated in terms of Ni ion release and human mesenchymal stem cell (hMSC) proliferation (AlamarBlue), differentiation (alkaline phosphatase activity, ALP) and mineralization (Alizarin Red S staining). Scanning electron microscopy was employed to qualitatively corroborate the results. hMSCs were able to adhere and proliferate on both as-produced and surface-modified trabecular NiTi scaffolds, to acquire an osteoblastic phenotype and produce a mineralized extracellular matrix. Both ALP activity and mineralization were increased on porous scaffolds compared to control polystyrene plates. Experiments in a model coculture system of microvascular endothelial cells and hMSCs demonstrated the formation of prevascular structures in trabecular NiTi scaffolds. These data suggest that load-bearing trabecular Nitinol scaffolds could be effective in regenerating damaged or lost bone tissue.

  9. Two and three-dimensional morphometric analysis of trabecular bone using X-ray microtomography (μCT)

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Alessandro Marcio Hakme da; Silva, Orivaldo Lopes da; Silva Junior, Nelson Ferreira da, E-mail: alhakme@sc.usp.br [Universidade de Sao Paulo (EESC/FMRP/IQSC/USP), Sao Carlos, SP (Brazil); Alves, Jose Marcos [Universidade de Sao Paulo (USP), Sao Carlos, SP (Brazil). Escola de Engenharia. Departamento de Engenharia Eletrica e Computacao

    2014-07-01

    Introduction: trabecular bones have a porous microstructure and can be modeled as linear elastic solids, heterogeneous and anisotropic. In the literature, few investigations have compared the two- dimensional (2D) and three-dimensional (3D) morphometric analyses of cancellous bone. Methods: In this investigation eighteen cylindrical samples of cancellous bone (10 mm of diameter and 20 mm of height) were obtained from six bovine head femurs, with similar values for the weight and age, of the same race and gender. The samples were harvested and freeze at - 20 °C before carrying out the micro CT analysis. The CT-Analyzer software was used to measure in three directions (superior-inferior, lateral-medial and anterior-posterior) parameters such as trabecular thickness, trabecular separation, trabecular number and the eigenvalues of the fabric tensor (M). Results: the Comparison of 2D and 3D analyses for the parameters: 2D (plate model) trabecular thickness, trabecular separation and trabecular number were statistically different (p = 0) showing that measurements are not similar to the 3D ones. However, 2D (rod model) trabecular thickness and 3D trabecular thickness measurements presented no significant difference (p = 0.26). The eigenvalues show that the bovine trabecular microstructure has a tendency to transversally isotropic symmetry. Discussion: The method proved to be quite interesting for the characterization of the bone structure through 3D measurements of trabecular bone morphometric parameters in the three possible directions of loading. The results show that x-ray microtomography (μCT) is a technique of great potential for characterization and generating bone quality parameters for the diagnosis of bone metabolism diseases. (author)

  10. Experimental observation of ultrasound fast and slow waves through three-dimensional printed trabecular bone phantoms.

    Science.gov (United States)

    Mézière, F; Juskova, P; Woittequand, J; Muller, M; Bossy, E; Boistel, Renaud; Malaquin, L; Derode, A

    2016-02-01

    In this paper, ultrasound measurements of 1:1 scale three-dimensional (3D) printed trabecular bone phantoms are reported. The micro-structure of a trabecular horse bone sample was obtained via synchrotron x-ray microtomography, converted to a 3D binary data set, and successfully 3D-printed at scale 1:1. Ultrasound through-transmission experiments were also performed through a highly anisotropic version of this structure, obtained by elongating the digitized structure prior to 3D printing. As in real anisotropic trabecular bone, both the fast and slow waves were observed. This illustrates the potential of stereolithography and the relevance of such bone phantoms for the study of ultrasound propagation in bone.

  11. NUMERICAL AND MECHANICAL ANALYSES OF A 3D-PRINTED TITANIUM TRABECULAR DENTAL IMPLANT

    Directory of Open Access Journals (Sweden)

    Luboš Řehounek

    2017-06-01

    Full Text Available The main focus of this paper is to investigate and describe a novel biomaterial structure. The trabecular structure has only recently been recognized as a viable alternative for prostheses and implants and seems to have very promising biocompatibility and mechanical properties. The 3D printing technique was used to create test specimens. These specimens were then tested by nanoindentation and tensile and compression tests. A numerical model was created and curve-fitted to represent the mechanical behavior of the trabecular structure. A significant reduction in the values of Young’s modulus E was observed. The values of E for conventional implant materials are approximately 110–120GPa and the trabecular structure reached a value just below 1GPa. The next effort will be to apply the model onto a real implant. It is the “four leaf clover” implant variant by authors F. Denk Jr., A. Jíra and F. Denk Sr.

  12. Dependence of ultrasonic scattering on frequency and microarchitecture in trabecular bone: Theory and experiment

    Science.gov (United States)

    Wear, Keith A.

    2002-05-01

    Measurements of ultrasonic properties of calcaneus (heel bone) have been shown to be effective for the diagnosis of osteoporosis. However, the mechanisms underlying the interaction between ultrasound and bone are currently not well understood. A model that predicts backscatter from trabecular bone has been developed. Scattering is assumed to originate from the surfaces of trabeculae, which are modeled as long, thin, elastic cylinders with radii small compared with the ultrasonic wavelength. Experimental measurements of backscatter using broadband ultrasound centered at 500 kHz from 43 trabecular bone samples (from human calcaneus) in vitro have been performed. Microcomputed tomography has been performed on all 43 samples in order to measure microarchitectural features. The theory correctly predicts the measured dependences of backscatter on ultrasonic frequency and trabecular thickness. [Funding from the FDA Office of Womens Health is gratefully acknowledged.

  13. Timing of growth hormone treatment affects trabecular bone microarchitecture and mineralization in growth hormone deficient mice.

    Science.gov (United States)

    Kristensen, Erika; Hallgrímsson, Benedikt; Morck, Douglas W; Boyd, Steven K

    2010-08-01

    Growth hormone (GH) is essential in the development of bone mass, and a growth hormone deficiency (GHD) in childhood is frequently treated with daily injections of GH. It is not clear what effect GHD and its treatment has on bone. It was hypothesized that GHD would result in impaired microarchitecture, and an early onset of treatment would result in a better recovery than late onset. Growth hormone deficient homozygous (lit/lit) mice of both sexes were divided into two treatment groups receiving daily injections of GH, starting at an early (21 days of age) or a late time point (35 days of age, corresponding to the end of puberty). A group of heterozygous mice with normal levels of growth hormone served as controls. In vivo micro-computed tomography scans of the fourth lumbar vertebra were obtained at five time points between 21 and 60 days of age, and trabecular morphology and volumetric BMD were analyzed to determine the effects of GH on bone microarchitecture. Early GH treatment led to significant improvements in bone volume ratio (p=0.006), tissue mineral density (p=0.005), and structure model index (p=0.004) by the study endpoint (day 60), with no detected change in trabecular thickness. Trabecular number increased and trabecular separation decreased in GHD mice regardless of treatment compared to heterozygous mice. This suggests fundamental differences in the structure of trabecular bone in GHD and GH treated mice, reflected by an increased number of thinner trabeculae in these mice compared to heterozygous controls. There were no significant differences between the late treatment group and GHD mice except for connectivity density. Taken together, these results indicate that bone responds to GH treatment initiated before puberty but not to treatment commencing post-puberty, and that GH treatment does not rescue the structure of trabecular bone to that of heterozygous controls. Copyright 2010 Elsevier Inc. All rights reserved.

  14. The effects of side-artifacts on the elastic modulus of trabecular bone.

    Science.gov (United States)

    Un, Kerem; Bevill, Grant; Keaveny, Tony M

    2006-01-01

    Determining accurate density-mechanical property relationships for trabecular bone is critical for correct characterization of this important structure-function relation. When testing any excised specimen of trabecular bone, an unavoidable experimental artifact originates from the sides of the specimen where peripheral trabeculae lose their vertical load-bearing capacity due to interruption of connectivity, a phenomenon denoted here as the 'side-artifact'. We sought in this study to quantify the magnitude of such side-artifact errors in modulus measurement and to do so as a function of the trabecular architecture and specimen size. Using parametric computational analysis of high-resolution micro-CT-based finite-element models of cores of elderly human vertebral trabecular bone, a specimen-specific correction factor for the side-artifact was quantified as the ratio of the side-artifact-free apparent modulus (Etrue) to the apparent modulus that would be measured in a typical experiment (Emeasured). We found that the width over which the peripheral trabeculae were mostly unloaded was between 0.19 and 0.58 mm. The side-artifact led to an underestimation error in Etrue of over 50% in some specimens, having a mean (+/-SD) of 27+/-11%. There was a trend for the correction factor to linearly increase as volume fraction decreased (p=0.001) and as mean trabecular separation increased (perror increased substantially as specimen size decreased. Two methods used for correcting for the side-artifact were both successful in bringing Emeasured into statistical agreement with Etrue. These findings have important implications for the interpretation of almost all literature data on trabecular bone mechanical properties since they indicate that such properties need to be adjusted to eliminate the substantial effects of side-artifacts in order to provide more accurate estimates of in situ behavior.

  15. Contribution of mechanical unloading to trabecular bone loss following non-invasive knee injury in mice.

    Science.gov (United States)

    Anderson, Matthew J; Diko, Sindi; Baehr, Leslie M; Baar, Keith; Bodine, Sue C; Christiansen, Blaine A

    2016-10-01

    Development of osteoarthritis commonly involves degeneration of epiphyseal trabecular bone. In previous studies, we observed 30-44% loss of epiphyseal trabecular bone (BV/TV) from the distal femur within 1 week following non-invasive knee injury in mice. Mechanical unloading (disuse) may contribute to this bone loss; however, it is unclear to what extent the injured limb is unloaded following injury, and whether disuse can fully account for the observed magnitude of bone loss. In this study, we investigated the contribution of mechanical unloading to trabecular bone changes observed following non-invasive knee injury in mice (female C57BL/6N). We investigated changes in gait during treadmill walking, and changes in voluntary activity level using Open Field analysis at 4, 14, 28, and 42 days post-injury. We also quantified epiphyseal trabecular bone using μCT and weighed lower-limb muscles to quantify atrophy following knee injury in both ground control and hindlimb unloaded (HLU) mice. Gait analysis revealed a slightly altered stride pattern in the injured limb, with a decreased stance phase and increased swing phase. However, Open Field analysis revealed no differences in voluntary movement between injured and sham mice at any time point. Both knee injury and HLU resulted in comparable magnitudes of trabecular bone loss; however, HLU resulted in considerably more muscle loss than knee injury, suggesting another mechanism contributing to bone loss following injury. Altogether, these data suggest that mechanical unloading likely contributes to trabecular bone loss following non-invasive knee injury, but the magnitude of this bone loss cannot be fully explained by disuse. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1680-1687, 2016.

  16. Measuring apparent trabecular structure with pQCT: a comparison with HR-pQCT.

    Science.gov (United States)

    Lala, Deena; Cheung, Angela M; Lynch, Cheryl L; Inglis, Dean; Gordon, Chris; Tomlinson, George; Giangregorio, Lora

    2014-01-01

    We evaluated how comparable peripheral quantitative computed tomography (pQCT) measurements of cortical thickness, density, and apparent trabecular structure at the ultradistal tibia were with those measured with high-resolution pQCT (HR-pQCT). We also examined whether the accuracy of the pQCT-based trabecular and cortical measurements improved with reductions in slice thickness from the standard 2.2mm to 1.1 and 0.6mm. We immersed 15 dry tibia specimens in saline in a sealed cylinder and scanned 22.5mm from the distal tibia plateau using pQCT and HR-pQCT. pQCT underestimated cortical thickness by Stratec (CThStratec) and trabecular spacing (Tb.Sp) by 21.4% and 72.9%, whereas bone volume to total volume (BV/TV) and cortical density (CDen) were overestimated by 265.8% and 13.1%, respectively. Measurements of trabecular volumetric bone mineral density, trabecular area, total area, cortical thickness by custom software were comparable, but for CThStratec, Tb.Sp, BV/TV, and CDen, the differences between imaging devices varied with magnitude of the estimate. We recommend that researchers or clinicians interested in using pQCT to measure apparent trabecular structure or cortical thickness at the epiphyses, or in comparing findings from different devices, be aware of the differences between HR-pQCT and pQCT. Copyright © 2014 The International Society for Clinical Densitometry. Published by Elsevier Inc. All rights reserved.

  17. Hyalinizing trabecular tumor of the thyroid gland: characteristic features on ultrasonography.

    Science.gov (United States)

    Kobayashi, Kaoru; Hirokawa, Mitsuyoshi; Jikuzono, Tomoo; Fukata, Shuji; Amino, Nobuyuki; Miyauchi, Akira; Nakamura, Yasushi

    2007-03-01

    We report a case of hyalinizing trabecular tumor of the thyroid gland and describe the characteristic ultrasonographic features of this tumor. This was a rare tumor of follicular cell origin with a trabecular pattern of growth and marked intratrabecular hyalinization. The tumor had an irregular shape, a delicately jagged border, and hypoechoic and heterogeneous internal echoes on B-mode ultrasonography. Very rich intratumoral blood flow, the so-called "tumor inferno" was evident on power Doppler ultrasonography. In the clinical management of thyroid nodules, clinicians should be aware of this peculiar type of thyroid tumor and its characteristic ultrasonographic findings.

  18. Microstructure-based Finite Element Modelling and Characterisation of Bovine Trabecular Bone

    Institute of Scientific and Technical Information of China (English)

    R. Akhtar; S. J. Eichhorn; P. M. Mummery

    2006-01-01

    The mechanical behaviour of trabecular bone is dependent on both the properties of individual trabeculae as well as their three-dimensional arrangement in space. In this study, nanoindentation was used to determine trabecular stiffness of bovine bone, both d ehydrated and rehydrated. Values of 18.3 GPa and 14.3 GPa were obtained for dehydrated and rehydrated trabeculae respectively. These values were then used for finite element analysis where the mesh was generated directly from an X-ray microtomography dataset. The relationship between intrinsic tissue properties and apparent stiffness was explored. Moreover, the important role of collagen in bone micromechanics was demonstrated by complementing the study with Raman spectroscopy.

  19. Static histomorphometry of human iliac crest and vertebral trabecular bone: a comparative study

    DEFF Research Database (Denmark)

    Thomsen, Jesper Skovhus; Ebbesen, Ebbe Nils; Mosekilde, Lis

    2002-01-01

    . In addition, connectivity density was measured (ConnEulor method). The results showed that the age-related changes in the static histomorphometric measures are generally similar in the iliac crest and the vertebral body, and that these age-related changes are independent of gender. An exception, however...... the generally similar pattern in age-related changes at these two skeletal sites. The highest correlation coefficient was found for trabecular separation (Tb.Sp; r = 0.63). Trabecular bone volume showed a correlation coefficient of r = 0.59. It is concluded that static histomorphometry performed on one skeletal...

  20. Distributional variations in trabecular architecture of the mandibular bone: an in vivo micro-CT analysis in rats.

    Directory of Open Access Journals (Sweden)

    Zhongshuang Liu

    Full Text Available To evaluate the effect of trabecular thickness and trabecular separation on modulating the trabecular architecture of the mandibular bone in ovariectomized rats.Fourteen 12-week-old adult female Wistar rats were divided into an ovariectomy group (OVX and a sham-ovariectomy group (sham. Five months after the surgery, the mandibles from 14 rats (seven OVX and seven sham were analyzed by micro-CT. Images of inter-radicular alveolar bone of the mandibular first molars underwent three-dimensional reconstruction and were analyzed.Compared to the sham group, trabecular thickness in OVX alveolar bone decreased by 27% (P = 0.012, but trabecular separation in OVX alveolar bone increased by 59% (P = 0.005. A thickness and separation map showed that trabeculae of less than 100 μm increased by 46%, whereas trabeculae of more than 200 μm decreased by more than 40% in the OVX group compared to those in the sham group. Furthermore, the OVX separation of those trabecular of more than 200 μm was 65% higher compared to the sham group. Bone mineral density (P = 0.028 and bone volume fraction (p = 0.001 were also significantly decreased in the OVX group compared to the sham group.Ovariectomy-induced bone loss in mandibular bone may be related to the distributional variations in trabecular thickness and separation which profoundly impact the modulation of the trabecular architecture.

  1. Accuracy of trabecular bone microstructural measurement at planned dental implant sites using cone-beam CT datasets

    NARCIS (Netherlands)

    Ibrahim, N.; Parsa, A.; Hassan, B.; van der Stelt, P.; Aartman, I.H.A.; Wismeijer, D.

    2014-01-01

    Objective Cone-beam CT (CBCT) images are infrequently utilized for trabecular bone microstructural measurement due to the system's limited resolution. The aim of this study was to determine the accuracy of CBCT for measuring trabecular bone microstructure in comparison with micro CT (μCT). Materials

  2. Trabecular architecture in the thumb of Pan and Homo: implications for investigating hand use, loading, and hand preference in the fossil record.

    Science.gov (United States)

    Stephens, Nicholas B; Kivell, Tracy L; Gross, Thomas; Pahr, Dieter H; Lazenby, Richard A; Hublin, Jean-Jacques; Hershkovitz, Israel; Skinner, Matthew M

    2016-12-01

    Humans display an 85-95% cross-cultural right-hand bias in skilled tasks, which is considered a derived behavior because such a high frequency is not reported in wild non-human primates. Handedness is generally considered to be an evolutionary byproduct of selection for manual dexterity and augmented visuo-cognitive capabilities within the context of complex stone tool manufacture/use. Testing this hypothesis requires an understanding of when appreciable levels of right dominant behavior entered the fossil record. Because bone remodels in vivo, skeletal asymmetries are thought to reflect greater mechanical loading on the dominant side, but incomplete preservation of external morphology and ambiguities about past loading environments complicate interpretations. We test if internal trabecular bone is capable of providing additional information by analyzing the thumb of Homo sapiens and Pan. We assess trabecular structure at the distal head and proximal base of paired (left/right) first metacarpals using micro-CT scans of Homo sapiens (n = 14) and Pan (n = 9). Throughout each epiphysis we quantify average and local bone volume fraction (BV/TV), degree of anisotropy (DA), and elastic modulus (E) to address bone volume patterning and directional asymmetry. We find a right directional asymmetry in H. sapiens consistent with population-level handedness, but also report a left directional asymmetry in Pan that may be the result of postural and/or locomotor loading. We conclude that trabecular bone is capable of detecting right/left directional asymmetry, but suggest coupling studies of internal structure with analyses of other skeletal elements and cortical bone prior to applications in the fossil record. © 2016 Wiley Periodicals, Inc.

  3. Prediction of progression of radiographic knee osteoarthritis using tibial trabecular bone texture

    DEFF Research Database (Denmark)

    Woloszynski, T; Podsiadlo, P; Stachowiak, G W

    2012-01-01

    OBJECTIVE.: To develop a system for prediction of progression of radiographic knee osteoarthritis (OA) using tibial trabecular bone (TB) texture. METHODS.: We studied 203 knees with (n=68) or without (n=135) radiographic tibiofemoral OA in 105 subjects (90 men, 15 women, mean age 54 years) who had...

  4. Osteocyte-viability-based simulations of trabecular bone loss and recovery in disuse and reloading

    NARCIS (Netherlands)

    Wang, H.; Ji, B.; Liu, X.S.; van Oers, R.F.M.; Guo, X.E.; Huang, Y.; Hwang, K.C.

    2014-01-01

    Osteocyte apoptosis is known to trigger targeted bone resorption. In the present study, we developed an osteocyte-viability-based trabecular bone remodeling (OVBR) model. This novel remodeling model, combined with recent advanced simulation methods and analysis techniques, such as the element-by-ele

  5. Multi-axial fatigue of trabecular bone with respect to normal walking

    CERN Document Server

    Mostakhdemin, Mohammad; Syahrom, Ardiyansyah

    2016-01-01

    This book focuses on the analysis and treatment of osteoporotic bone based on drug administration, tracking fatigue behavior and taking into consideration the mechanical interaction of implants with trabecular bone. Weak trabeculae are one of the most important clinical features that need to be addressed in order to prevent hip joint fractures.

  6. Sparseness of the trabecular pattern on dental radiographs: visual assessment compared with semi-automated measurements

    NARCIS (Netherlands)

    Geraets, W.G.M.; Lindh, C.; Verheij, H.

    2012-01-01

    Objective: In diagnostic imaging; human perception is the most prominent, yet least studied, source of error. A better understanding of image perception will help to improve diagnostic performance. This study focuses on the perception of coarseness of trabecular patterns on dental radiographs. Compa

  7. Three-dimensional microstructure of human alveolar trabecular bone: a micro-computed tomography study

    Science.gov (United States)

    2017-01-01

    Purpose The microstructural characteristics of trabecular bone were identified using micro-computed tomography (micro-CT), in order to develop a potential strategy for implant surface improvement to facilitate osseointegration. Methods Alveolar bone specimens from the cadavers of 30 humans were scanned by high-resolution micro-CT and reconstructed. Volumes of interest chosen within the jaw were classified according to Hounsfield units into 4 bone quality categories. Several structural parameters were measured and statistically analyzed. Results Alveolar bone specimens with D1 bone quality had significantly higher values for all structural parameters than the other bone quality categories, except for trabecular thickness (Tb.Th). The percentage of bone volume, trabecular separation (Tb.Sp), and trabecular number (Tb.N) varied significantly among bone quality categories. Tb.Sp varied markedly across the bone quality categories (D1: 0.59±0.22 mm, D4: 1.20±0.48 mm), whereas Tb.Th had similar values (D1: 0.30±0.08 mm, D4: 0.22±0.05 mm). Conclusions Bone quality depended on Tb.Sp and number—that is, endosteal space architecture—rather than bone surface and Tb.Th. Regardless of bone quality, Tb.Th showed little variation. These factors should be taken into account when developing individualized implant surface topographies. PMID:28261521

  8. Effects of deleting cannabinoid receptor-2 on mechanical and material properties of cortical and trabecular bone

    Directory of Open Access Journals (Sweden)

    Aysha B. Khalid

    2015-12-01

    Full Text Available Cnr2 is one of two cannabinoid receptors known to regulate bone metabolism. Here, we compared the whole bone properties of femora and tibiae from three-month-old Cnr2−/- mice with wild-type controls using a C57BL/6 background. Bending stiffness was measured by three-point bending. The elastic modulus, density and mineral content were measured using ultrasound, Archimedes’ principle and ashing. Micro-CT was used to measure the second moment of area, inner and outer perimeters of the cortical shaft and trabecular parameters. Deleting Cnr2 increased the bending stiffness by increasing the second moment of area. Bone from affected male mice had a greater modulus than controls, although no difference was observed in females. The fractional volume of trabecular bone was greater in Cnr2−/- females than controls, while no difference was seen in males. These data indicate that inactivating Cnr2 increases the amount of cortical bone in both males and females at 3 months of age, but the effect on trabecular bone is different in the two sexes. These findings extend previous studies looking only at trabecular bone and provide further support for the possible use of Cnr2 antagonists for improving bone properties that may be of value in the treatment of bone disorders.

  9. Calorie restriction aggravated cortical and trabecular bone architecture in ovariectomy-induced estrogen-deficient rats.

    Science.gov (United States)

    Ahn, Hyejin; Seo, Dong-Hyun; Kim, Han Sung; Choue, Ryowon

    2014-08-01

    We hypothesized that calorie restriction (CR) and estrogen deficiency (ovariectomy [OVX]) would aggravate bone biomarkers and structural parameters in rats. Seven-week-old female Sprague-Dawley rats were randomized to sham-operated groups and fed either an ad libitum diet (SHAM-AL) or a CR diet (SHAM-CR); ovariectomy-operated groups were fed an ad libitum diet (OVX-AL) or a CR diet (OVX-CR). For 8 weeks, the OVX-AL and SHAM-AL groups were fed the same diet, whereas CR groups were fed a diet containing 50% fewer calories. Bone-related biomarkers and structural parameters (OC; deoxypyridinoline [DPD]; N-terminal telopeptide, NTx; architecture and mineralization; and microcomputed tomography images) were analyzed at the end of the experiment. The serum OC levels of calorie-restricted groups (SHAM-CR and OVX-CR) were significantly lower than those of the AL groups (SHAM-AL and OVX-AL) (P bone, the calorie-restricted and ovariectomized groups had lower values of bone volume to total volume, trabecular number, and bone mineral density, but higher values of trabecular separation than those of their counterparts (P bone, the calorie-restricted groups had reduced values of bone volume, mean polar moment of inertia, and cortical thickness compared to the AL groups (P bone; CR has detrimental effects on trabecular and cortical bone; and estrogen deficiency only had an effect on trabecular bone. Copyright © 2014 Elsevier Inc. All rights reserved.

  10. Revision total knee arthroplasty with the use of trabecular metal cones

    DEFF Research Database (Denmark)

    Jensen, Claus L; Petersen, Michael Mygind; Schrøder, Henrik;

    2012-01-01

    "Trabecular Metal Cone" (TM Cone) (Zimmer, Inc, Warsaw, Ind) for reconstruction of bone loss in the proximal tibia during revision total knee arthroplasty is now optional. Forty patients were randomized to receive revision total knee arthroplasty with or without TM Cone (No TM Cone). The Anderson...

  11. Sparseness of the trabecular pattern on dental radiographs: visual assessment compared with semi-automated measurements

    NARCIS (Netherlands)

    Geraets, W.G.M.; Lindh, C.; Verheij, H.

    2012-01-01

    Objective: In diagnostic imaging; human perception is the most prominent, yet least studied, source of error. A better understanding of image perception will help to improve diagnostic performance. This study focuses on the perception of coarseness of trabecular patterns on dental radiographs. Compa

  12. Effect of boundary conditions on yield properties of human femoral trabecular bone.

    Science.gov (United States)

    Panyasantisuk, J; Pahr, D H; Zysset, P K

    2016-10-01

    Trabecular bone plays an important mechanical role in bone fractures and implant stability. Homogenized nonlinear finite element (FE) analysis of whole bones can deliver improved fracture risk and implant loosening assessment. Such simulations require the knowledge of mechanical properties such as an appropriate yield behavior and criterion for trabecular bone. Identification of a complete yield surface is extremely difficult experimentally but can be achieved in silico by using micro-FE analysis on cubical trabecular volume elements. Nevertheless, the influence of the boundary conditions (BCs), which are applied to such volume elements, on the obtained yield properties remains unknown. Therefore, this study compared homogenized yield properties along 17 load cases of 126 human femoral trabecular cubic specimens computed with classical kinematic uniform BCs (KUBCs) and a new set of mixed uniform BCs, namely periodicity-compatible mixed uniform BCs (PMUBCs). In stress space, PMUBCs lead to 7-72 % lower yield stresses compared to KUBCs. The yield surfaces obtained with both KUBCs and PMUBCs demonstrate a pressure-sensitive ellipsoidal shape. A volume fraction and fabric-based quadric yield function successfully fitted the yield surfaces of both BCs with a correlation coefficient [Formula: see text]. As expected, yield strains show only a weak dependency on bone volume fraction and fabric. The role of the two BCs in homogenized FE analysis of whole bones will need to be investigated and validated with experimental results at the whole bone level in future studies.

  13. On the effect of marrow in the mechanical behavior and crush response of trabecular bone.

    Science.gov (United States)

    Halgrin, J; Chaari, F; Markiewicz, É

    2012-01-01

    The present paper focuses on the mechanical behavior analysis of bones at mesoscopic scale, paying a special attention to the trabecular bone and the bone marrow filling the porosities. Uni-axial quasi-static compression tests under unconfined conditions have been performed to identify the mechanical behavior of 46 trabecular bone samples. The bone marrow for 22 samples has been preserved to analyze the fluid flow effects on the crushing response. Although deformation patterns do not differ significantly, the average crush behavior of the trabecular bone shows an unexpected decrease of the mechanical properties when the marrow is kept in the sample (26% for the elastic modulus (E(a)), 38% for the maximum compressive stress (σ(max)) and 33% for the average stress (σ(mean))). An explanation is given by analyzing the contribution of the bone marrow viscosity which smooths the mechanical response. A numerical analysis on an idealized trabecula confirms that the marrow induces transverse pressure and extra local stress on trabeculae during its flow, causing the premature collapse of the trabecular network. Copyright © 2011 Elsevier Ltd. All rights reserved.

  14. Genetic determinants of trabecular and cortical volumetric bone mineral densities and bone microstructure.

    Directory of Open Access Journals (Sweden)

    Lavinia Paternoster

    Full Text Available Most previous genetic epidemiology studies within the field of osteoporosis have focused on the genetics of the complex trait areal bone mineral density (aBMD, not being able to differentiate genetic determinants of cortical volumetric BMD (vBMD, trabecular vBMD, and bone microstructural traits. The objective of this study was to separately identify genetic determinants of these bone traits as analysed by peripheral quantitative computed tomography (pQCT. Separate GWA meta-analyses for cortical and trabecular vBMDs were performed. The cortical vBMD GWA meta-analysis (n = 5,878 followed by replication (n = 1,052 identified genetic variants in four separate loci reaching genome-wide significance (RANKL, rs1021188, p = 3.6×10⁻¹⁴; LOC285735, rs271170, p = 2.7×10⁻¹²; OPG, rs7839059, p = 1.2×10⁻¹⁰; and ESR1/C6orf97, rs6909279, p = 1.1×10⁻⁹. The trabecular vBMD GWA meta-analysis (n = 2,500 followed by replication (n = 1,022 identified one locus reaching genome-wide significance (FMN2/GREM2, rs9287237, p = 1.9×10⁻⁹. High-resolution pQCT analyses, giving information about bone microstructure, were available in a subset of the GOOD cohort (n = 729. rs1021188 was significantly associated with cortical porosity while rs9287237 was significantly associated with trabecular bone fraction. The genetic variant in the FMN2/GREM2 locus was associated with fracture risk in the MrOS Sweden cohort (HR per extra T allele 0.75, 95% confidence interval 0.60-0.93 and GREM2 expression in human osteoblasts. In conclusion, five genetic loci associated with trabecular or cortical vBMD were identified. Two of these (FMN2/GREM2 and LOC285735 are novel bone-related loci, while the other three have previously been reported to be associated with aBMD. The genetic variants associated with cortical and trabecular bone parameters differed, underscoring the complexity of the genetics of bone parameters. We propose

  15. Static histomorphometry of human iliac crest and vertebral trabecular bone: a comparative study.

    Science.gov (United States)

    Thomsen, J S; Ebbesen, E N; Mosekilde, Li

    2002-01-01

    We recently developed a new, rapid method for conducting static histomorphometry on large histologic sections. This method has now been applied on both iliac crest and lumbar vertebral bone to compare the age-related changes at these two skeletal sites and to investigate the correlation between the histomorphometric measures at the iliac crest and the vertebral body. The material comprised matched sets of unilateral transiliac crest bone biopsies and lumbar vertebral bodies (L-2) from 24 women (19-96 years) and 24 men (23-95 years) selected from a larger autopsy material. Three female subjects (80, 88, and 90 years) had a known vertebral fracture of L-2. The iliac crest biopsies and 9-mm-thick mediolateral slices of half the entire vertebral bodies were embedded in methylmetacrylate, stained with aniline blue, and scanned into a computer with a flatbed image scanner at a high resolution. With a custom-made computer program the following static histomorphometric measures were determined: trabecular bone volume; marrow and bone space star volume; node-strut analysis; trabecular bone pattern factor; trabecular thickness; trabecular number; trabecular separation; and anisotropy of bone and marrow phase. In addition, connectivity density was measured (ConnEulor method). The results showed that the age-related changes in the static histomorphometric measures are generally similar in the iliac crest and the vertebral body, and that these age-related changes are independent of gender. An exception, however, is connectivity density, where the age-related changes are similar for women and men in the vertebral body but significantly different in the iliac crest. Furthermore, the results showed that the histomorphometric measures were weakly intercorrelated between the iliac crest and the vertebral body, despite the generally similar pattern in age-related changes at these two skeletal sites. The highest correlation coefficient was found for trabecular separation (Tb.Sp; r = 0

  16. Quantifying trabecular bone material anisotropy and orientation using low resolution clinical CT images: A feasibility study.

    Science.gov (United States)

    Nazemi, S Majid; Cooper, David M L; Johnston, James D

    2016-09-01

    Accounting for spatial variation of trabecular material anisotropy and orientation can improve the accuracy of quantitative computed tomography-based finite element (FE) modeling of bone. The objective of this study was to investigate the feasibility of quantifying trabecular material anisotropy and orientation using clinical computed tomography (CT). Forty four cubic volumes of interest were obtained from micro-CT images of the human radius. Micro-FE modeling was performed on the samples to obtain orthotropic stiffness entries as well as trabecular orientation. Simulated computed tomography images (0.32, 0.37, and 0.5mm isotropic voxel sizes) were created by resampling micro-CT images with added image noise. The gray-level structure tensor was used to derive fabric eigenvalues and eigenvectors in simulated CT images. For 'best case' comparison purposes, Mean Intercept Length was used to define fabric from micro-CT images. Regression was used in combination with eigenvalues, imaged density and FE to inversely derive the constants used in Cowin and Zysset-Curnier fabric-elasticity equations, and for comparing image derived fabric-elasticity stiffness entries to those obtained using micro-FE. Image derived eigenvectors (which indicated trabecular orientation) were then compared to orientation derived using micro-FE. When using clinically available voxel sizes, gray-level structure tensor derived fabric combined with Cowin's equations was able to explain 94-97% of the variance in orthotropic stiffness entries while Zysset-Curnier equations explained 82-88% of the variance in stiffness. Image derived orientation deviated by 4.4-10.8° from micro-FE derived orientation. Our results indicate potential to account for spatial variation of trabecular material anisotropy and orientation in subject-specific finite element modeling of bone using clinically available CT.

  17. Reduced tissue hardness of trabecular bone is associated with severe osteoarthritis.

    Science.gov (United States)

    Dall'Ara, Enrico; Ohman, Caroline; Baleani, Massimiliano; Viceconti, Marco

    2011-05-17

    This study investigated whether changes in hardness of human trabecular bone are associated with osteoarthritis. Twenty femoral heads extracted from subjects without musculoskeletal diseases (subject age: 49-83 years) and twenty femoral heads extracted from osteoarthritic subjects (subject age: 42-85 years) were tested. Sixty indentations were performed along the main trabecular direction of each sample at a fixed relative distance. Two microstructures were found on the indenting locations: packs of parallel-lamellae (PL) and secondary osteons (SO). A 25gf load was applied for 15s and the Vickers Hardness (HV) was assessed. Trabecular tissue extracted from osteoarthritic subjects was found to be about 13% less hard compared to tissue extracted from non-pathologic subjects. However, tissue hardness was not significantly affected by gender or age. The SO was 10% less hard than the PL for both pathologic and non-pathologic tissues. A hardness of 34.1HV for PL and 30.8HV for SO was found for the non-pathologic tissue. For osteoarthritic tissue, the hardness was 30.2HV for PL and 27.1HV for SO. In the bone tissue extracted from osteoarthritic subjects the occurrence of indenting a SO (28%) was higher than that observed in the non-pathological tissue (15%). Osteoarthritis is associated with reduced tissue hardness and alterations in microstructure of the trabecular bone tissue. Gender does not significantly affect trabecular bone hardness either in non-pathological or osteoarthritic subjects. A similar conclusion can be drawn for age, although a larger donor sample size would be necessary to definitively exclude the existence of a slight effect.

  18. 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 parameters and FL amounted up to r = 0.86 (p parameters obtained with HR-pQCT and MDCT were not significantly different (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.

  19. Trabecular bone structure analysis in the limited spatial resolution regime of in vivo MRI.

    Science.gov (United States)

    Magland, Jeremy F; Wehrli, Felix W

    2008-12-01

    To develop a method for processing and visualization of trabecular bone networks on the basis of magnetic resonance (MR) images acquired in the limited spatial resolution regime of in vivo imaging at which trabecular thickness is comparable to voxel size. A sequence of processing steps for analyzing the topologic structure of trabecular bone networks is presented and evaluated using three types of datasets: images of synthetic structures with various levels of superimposed Gaussian noise, micro-computed tomographic images of human trabecular bone downsampled to in vivo resolution, and in vivo micro-MR images from a prior longitudinal study investigating the structural implications of testosterone treatment of hypogonadal men. The simulated images were analyzed at a voxel size of 150 microm(3), the clinical MR image data had been acquired with 137 x 137 x 410 microm(3) voxel size. The technique is a modification to the virtual bone biopsy processing chain that involves a sinc convolution step immediately preceding binarization, and employs the Manzanera-Bernard thinning algorithm for obtaining the three-dimensional skeleton before topologic classification. The detectability of plate and rod bone elements was also analyzed theoretically. As compared with previously published techniques, the approach produced a more accurate bone skeleton in the micro-computed tomographic and simulation experiments, with clear improvement in preservation of rod and plate elements. Simulations suggest that rods are detectable down to a diameter of approximately 50% of the MR image voxel length, whereas plates can be detected at thicknesses of 20% or more of voxel length. For in vivo studies, it was shown that the method could recover the treatment response in terms of the ensuing topologic changes in patients undergoing antiresorptive treatment. The algorithm for processing of in vivo micro-MR images of trabecular bone is superior to prior approaches in preserving the topology of the

  20. Does skeletal anatomy reflect adaptation to locomotor patterns? Cortical and trabecular architecture in human and nonhuman anthropoids.

    Science.gov (United States)

    Shaw, Colin N; Ryan, Timothy M

    2012-02-01

    Although the correspondence between habitual activity and diaphyseal cortical bone morphology has been demonstrated for the fore- and hind-limb long bones of primates, the relationship between trabecular bone architecture and locomotor behavior is less certain. If sub-articular trabecular and diaphyseal cortical bone morphology reflects locomotor patterns, this correspondence would be a valuable tool with which to interpret morphological variation in the skeletal and fossil record. To assess this relationship, high-resolution computed tomography images from both the humeral and femoral head and midshaft of 112 individuals from eight anthropoid genera (Alouatta, Homo, Macaca, Pan, Papio, Pongo, Trachypithecus, and Symphalangus) were analyzed. Within-bone (sub-articular trabeculae vs. mid-diaphysis), between-bone (forelimb vs. hind limb), and among-taxa relative distributions (femoral:humeral) were compared. Three conclusions are evident: (1) Correlations exists between humeral head sub-articular trabecular bone architecture and mid-humerus diaphyseal bone properties; this was not the case in the femur. (2) In contrast to comparisons of inter-limb diaphyseal bone robusticity, among all species femoral head trabecular bone architecture is significantly more substantial (i.e., higher values for mechanically relevant trabecular bone architectural features) than humeral head trabecular bone architecture. (3) Interspecific comparisons of femoral morphology relative to humeral morphology reveal an osteological "locomotor signal" indicative of differential use of the forelimb and hind limb within mid-diaphysis cortical bone geometry, but not within sub-articular trabecular bone architecture. Copyright © 2011 Wiley Periodicals, Inc.

  1. C-arm CT for histomorphometric evaluation of lumbar spine trabecular microarchitecture: a study on anorexia nervosa patients.

    Science.gov (United States)

    Phan, C M; Khalilzadeh, O; Dinkel, J; Wang, I S; Bredella, M A; Misra, M; Miller, K K; Klibanski, A; Gupta, R

    2013-07-01

    Bone histomorphometry measurements require high spatial resolution that may not be feasible using multidetector CT (MDCT). This study evaluated the trabecular microarchitecture of lumbar spine using MDCT and C-arm CT in a series of young adult patients with anorexia nervosa (AN). 11 young females with AN underwent MDCT (anisotropic resolution with a slice thickness of ~626 μm) and C-arm CT (isotropic resolution of ~200 µm). Standard histomorphometric parameters the of L1 vertebral body, namely the apparent trabecular bone volume fraction (BV/TV), trabecular thickness (TbTh), trabecular number (TbN) and trabecular separation (TbSp), were analysed using MicroView software (GE Healthcare, Piscataway, NJ). Bone mineral density (BMD) was measured using dual-energy X-ray absorptiometry. Trabecular parameters derived from MDCT and C-arm CT were compared, and their association with BMD parameters was evaluated. Histomorphometric parameters derived from C-arm CT, namely TbTh, TbN and TbSp, were significantly different from the corresponding MDCT parameters. There were no significant correlations between C-arm CT-derived parameters and the corresponding MDCT-derived parameters. C-arm CT-derived parameters were significantly (pC-arm CT, was significantly associated with body mass index (r=0.636) and ideal body weight (r=0.730) (pC-arm CT more accurately captures the histomorphometric parameters of trabecular morphology than MDCT in patients with AN.

  2. 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

  3. PTH (1–34), but not strontium ranelate counteract loss of trabecular thickness and bone strength in disuse osteopenic rats

    DEFF Research Database (Denmark)

    Brüel, Annemarie; Vegger, Jens Bay; Raffalt, Anders Christer;

    2013-01-01

    +PTH+SrR (n=12 in each group). PTH was given as injections (SC) at a dosage of 60 μg/kg/d, and SrR as 900 mg/kg/d in the diet. The experiment lasted for 4weeks.BTX resulted in lower trabecular bone formation rate (−68%) and periosteal bone formation rate (−91%), and a higher fraction of osteoclast......) and periosteal (5-fold increase vs. BTX) bone formation rate, trabecular thickness (+25% vs. BTX) and femoral neck strength (+24% vs. BTX). In contrast, SrR did not influence BTX-induced loss of bone formation rate, trabecular bone volume fraction, trabecular thickness, or bone strength. Finally, no additive...

  4. Measurement of the speed of sound in trabecular bone by using a time reversal acoustics focusing system

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kang Il [Kangwon National University, Chuncheon (Korea, Republic of); Choi, Bok-Kyoung [Maritime Security Research Center, KIOST, Ansan (Korea, Republic of)

    2014-10-15

    A new method for measuring the speed of sound (SOS) in trabecular bone by using a time reversal acoustics (TRA) focusing system was proposed and validated with measurements obtained by using the conventional pulse-transmission technique. The SOS measured in 14 bovine femoral trabecular bone samples by using the two methods was highly correlated each other, although the SOS measured by using the TRA focusing system was slightly lower by an average of 2.2 m/s. The SOS measured by using the two methods showed high correlation coefficients of r = 0.92 with the apparent bone density, consistent with the behavior in human trabecular bone in vitro. These results prove the efficacy of the new method based on the principle of TRA to measure the SOS in trabecular bone.

  5. A critical damping approach for assessing the role of marrow fat on the mechanical strength of trabecular bone.

    Science.gov (United States)

    Braidotti, P; Stagni, L

    2007-01-01

    Several clinical findings revealed that post-menopausal osteoporosis and age-related osteopenia are accompanied by trabecular bone marrow fat (BMF) increase. To help understand this phenomenon, a vibrating string model is proposed, based on the hypothesis that, when bone marrow properties change, the trabecular bone structure remodels itself to preserve its critical damping state. It is found that an inverse relationship holds between trabecular average length and marrow damping coefficient. Such a result leads us to hypothesize the following bone-weakening mechanism. Since fat-rich bone marrow is a worse damper, a BMF increment causes an increase of trabecular average length, which is accomplished by the absorption of horizontal trabeculae (structurally less important than vertical trabeculae). The resulting bone patterns are in excellent agreement with clinical observations of osteoporotic bone. A definitive confirmation of the proposed mechanism will support a therapeutical approach to widespread osteopenic diseases aimed at avoiding, or limiting, BMF increase.

  6. Simulations of trabecular remodeling and fatigue: is remodeling helpful or harmful?

    Science.gov (United States)

    van Oers, René F M; van Rietbergen, Bert; Ito, Keita; Huiskes, Rik; Hilbers, Peter A J

    2011-05-01

    Microdamage-targeted resorption is paradoxal, because it entails the removal of bone from a region that was already overloaded. Under continued intense loading, resorption spaces could potentially cause more damage than they remove. To investigate this problem, we incorporated damage algorithms in a computer-simulation model for trabecular remodeling. We simulated damage accumulation and bone remodeling in a trabecular architecture, for two fatigue regimens, a 'moderate' regimen, and an 'intense' regimen with a higher number of loading cycles per day. Both simulations were also performed without bone remodeling to investigate if remodeling removed or exacerbated the damage. We found that remodeling tends to remove damage under the 'moderate' fatigue regimen, but it exacerbates damage under the 'intense' regimen. This harmful effect of remodeling may play a role in the development of stress fractures.

  7. Age variations in the properties of human tibial trabecular bone and cartilage

    DEFF Research Database (Denmark)

    Ding, Ming

    2000-01-01

    ) to investigate the age-related and osteoarthrosis-related changes in the mechanical properties of the human tibial cartilage-bone complex; and 3) to evaluate mutual associations among various properties. Normal specimens from human autopsy proximal tibiae were used for investigation of age variations...... in the properties of trabecular bone and the cartilage-bone complex, and osteoarthrotic specimens were used for the investigation of changes in the mechanical properties of the cartilage-bone complex induced by this disease process. The mechanical properties and physical/compositional properties of trabecular bone...... is parallel to the longitudinal loading axis of the tibia. The mechanical properties of the normal cartilage and bone vary with age and respond simultaneously to mechanical loading. Both cartilage and bone in early-stage OA are mechanically inferior to normal, and OA cartilage and bone have lost their unit...

  8. Metrology applied to ultrasound characterization of trabecular bones using the AIB parameter

    Science.gov (United States)

    Braz, D. S.; Silva, C. E.; Alvarenga, A. V.; Junior, D. S.; Costa-Félix, R. P. B.

    2016-07-01

    Apparent Integrated Backscattering (AIB) presents correlation between Apparent Backscatter Transfer Function and the transducer bandwidth. Replicas of trabecular bones (cubes of 20 mm side length) created by 3D printing technique were characterized using AIB with a 2.25 MHz center frequency transducer. A mechanical scanning system was used to acquire multiple backscatter signals. An uncertainty model in measurement was proposed based on the Guide to the Expression of Uncertainty in Measurement. Initial AIB results are not metrologically reliable, presenting high measurement uncertainties (sample: 5_0.2032/AIB: -15.1 dB ± 13.9 dB). It is noteworthy that the uncertainty model proposed contributes as unprecedented way for metrological assessment of trabecular bone characterization using AIB.

  9. Kramers-Kronig analysis of attenuation and dispersion in trabecular bone.

    Science.gov (United States)

    Waters, Kendall R; Hoffmeister, Brent K

    2005-12-01

    A restricted-bandwidth form of the Kramers-Kronig dispersion relations is applied to in vitro measurements of ultrasonic attenuation and dispersion properties of trabecular bone specimens from bovine tibia. The Kramers-Kronig analysis utilizes only experimentally measured properties and avoids extrapolation of ultrasonic properties beyond the known bandwidth. Compensation for the portions of the Kramers-Kronig integrals over the unknown bandwidth is partially achieved by the method of subtractions, where a subtraction frequency acts as an adjustable parameter. Good agreement is found between experimentally measured and Kramers-Kronig reconstructed dispersions. The restricted-bandwidth approach improves upon other forms of the Kramers-Kronig relations and may provide further insight into how ultrasound interacts with trabecular bone.

  10. Decreased trabecular bone biomechanical competence, apparent density, IGF-II and IGFBP-5 content in acromegaly

    DEFF Research Database (Denmark)

    Ueland, Thor; Ebbesen, Ebbe Nils; Thomsen, Jesper Skovhus;

    2002-01-01

    of these growth factors in relation to biomechanical properties in acromegaly. MATERIALS AND METHODS: Trabecular bone biomechanical competence (compression test), apparent density (peripheral quantitative computed tomography, pQCT), and bone matrix contents of calcium (HCl hydrolysis) and IGFs (guanidinium......-HCl extraction) were measured in iliac crest biopsies from 13 patients with active acromegaly (two women and 11 men, aged 21-61 years) and 21 age- and sex-matched controls (four women and 17 men, aged 23-64 years). RESULTS: Trabecular bone pQCT was reduced in acromegalic patients compared with controls (P = 0...... bone content of IGF-I, IGFBP-3, or osteocalcin. However, IGF-II and IGFBP-5 content was decreased (P acromegaly, supporting previous observations...

  11. Total water, phosphorus relaxation and inter-atomic organic to inorganic interface are new determinants of trabecular bone integrity.

    Science.gov (United States)

    Rai, Ratan Kumar; Barbhuyan, Tarun; Singh, Chandan; Mittal, Monika; Khan, Mohd Parvez; Sinha, Neeraj; Chattopadhyay, Naibedya

    2013-01-01

    Bone is the living composite biomaterial having unique structural property. Presently, there is a considerable gap in our understanding of bone structure and composition in the native state, particularly with respect to the trabecular bone, which is metabolically more active than cortical bones, and is readily lost in post-menopausal osteoporosis. We used solid-state nuclear magnetic resonance (NMR) to compare trabecular bone structure and composition in the native state between normal, bone loss and bone restoration conditions in rat. Trabecular osteopenia was induced by lactation as well as prolonged estrogen deficiency (bilateral ovariectomy, Ovx). Ovx rats with established osteopenia were administered with PTH (parathyroid hormone, trabecular restoration group), and restoration was allowed to become comparable to sham Ovx (control) group using bone mineral density (BMD) and µCT determinants. We used a technique combining (1)H NMR spectroscopy with (31)P and (13)C to measure various NMR parameters described below. Our results revealed that trabecular bones had diminished total water content, inorganic phosphorus NMR relaxation time (T1) and space between the collagen and inorganic phosphorus in the osteopenic groups compared to control, and these changes were significantly reversed in the bone restoration group. Remarkably, bound water was decreased in both osteopenic and bone restoration groups compared to control. Total water and T1 correlated strongly with trabecular bone density, volume, thickness, connectivity, spacing and resistance to compression. Bound water did not correlate with any of the microarchitectural and compression parameters. We conclude that total water, T1 and atomic space between the crystal and organic surface are altered in the trabecular bones of osteopenic rats, and PTH reverses these parameters. Furthermore, from these data, it appears that total water and T1 could serve as trabecular surrogates of micro-architecture and compression

  12. Total water, phosphorus relaxation and inter-atomic organic to inorganic interface are new determinants of trabecular bone integrity.

    Directory of Open Access Journals (Sweden)

    Ratan Kumar Rai

    Full Text Available Bone is the living composite biomaterial having unique structural property. Presently, there is a considerable gap in our understanding of bone structure and composition in the native state, particularly with respect to the trabecular bone, which is metabolically more active than cortical bones, and is readily lost in post-menopausal osteoporosis. We used solid-state nuclear magnetic resonance (NMR to compare trabecular bone structure and composition in the native state between normal, bone loss and bone restoration conditions in rat. Trabecular osteopenia was induced by lactation as well as prolonged estrogen deficiency (bilateral ovariectomy, Ovx. Ovx rats with established osteopenia were administered with PTH (parathyroid hormone, trabecular restoration group, and restoration was allowed to become comparable to sham Ovx (control group using bone mineral density (BMD and µCT determinants. We used a technique combining (1H NMR spectroscopy with (31P and (13C to measure various NMR parameters described below. Our results revealed that trabecular bones had diminished total water content, inorganic phosphorus NMR relaxation time (T1 and space between the collagen and inorganic phosphorus in the osteopenic groups compared to control, and these changes were significantly reversed in the bone restoration group. Remarkably, bound water was decreased in both osteopenic and bone restoration groups compared to control. Total water and T1 correlated strongly with trabecular bone density, volume, thickness, connectivity, spacing and resistance to compression. Bound water did not correlate with any of the microarchitectural and compression parameters. We conclude that total water, T1 and atomic space between the crystal and organic surface are altered in the trabecular bones of osteopenic rats, and PTH reverses these parameters. Furthermore, from these data, it appears that total water and T1 could serve as trabecular surrogates of micro-architecture and

  13. USING TRABECULAR METAL AUGMENTS FOR TOTAL HIP REPLACEMENT IN PATIENTS AFTER ACETABULAR FRACTURES

    Directory of Open Access Journals (Sweden)

    R. M. Tikhilov

    2011-01-01

    Full Text Available The authors presented the experience of treatment of two patients with hip arthritis after acetabular fracture. Both patients were treated with total hip replacement. During the operation, to manage posterior-superior bone defects of the acetabulum, augments of trabecular metal were used. Pain and limitation of motions in hip were indications for operative treatment. After a year of follow up there was no pain in hip; also recovery of motion and improved quality of life were observed.

  14. Relationships between age and microarchitectural descriptors of iliac trabecular bone determined by microCT.

    Science.gov (United States)

    Deguette, C; Ramond-Roquin, A; Rougé-Maillart, C

    2017-06-01

    Estimation of age at death is a major issue in anthropology. The main anthropological histological methods propose studying the architecture of cortical bone. In bone histomorphometry, researches on metabolic bone diseases have provided normative tables for trabecular bone volume (BV/TV) according to age and gender of individuals on trans-iliac bone biopsies. We have used microCT, a non-destructive tool for measuring bone volume and trabecular descriptors to compare the French tables to a series of forensic anthropological population and if the two iliac bones could be used interchangeably. Coxal bone of a personal forensic collection whose age and gender were known (DNA identification) were used. Bone samples, centered on the same area than bone biopsy. MicroCT (pixel size: 36μm) was used to measure BV/TV and morphometric trabecular parameters of microarchitecture. An adjusted Z-score was calculated for BV/TV to compare with normative tables and a right/left comparison of trabecular parameters was provided. Twenty-seven iliac bones, which 20 forming 10 complete pelvises, aged between 24 and 73y.o. (average of 47.7 y.o.) were used. All adjusted Z-score were within normal values. There was a strong positive correlation between right and left sides for Tb.Th, Tb.N and Tb.Sp, but an insignificant correlation was obtained for BV/TV. Normative tables between age and BV/TV are valid and therefore usable in anthropology. They may represent an alternative to determine the age at death. Nevertheless, it requires a precise technique that could be a drawback in current practice. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  15. Trabecular bone structure parameters from 3D image processing of clinical multi-slice and cone-beam computed tomography data

    Energy Technology Data Exchange (ETDEWEB)

    Klintstroem, Eva; Smedby, Oerjan [Linkoeping University, Center for Medical Image Science and Visualization (CMIV), Linkoeping (Sweden); UHL County Council of Oestergoetland, Department of Radiology, Linkoeping (Sweden); Linkoeping University, Department of Medical and Health Sciences (IMH)/Radiology, Linkoeping (Sweden); Moreno, Rodrigo [Linkoeping University, Center for Medical Image Science and Visualization (CMIV), Linkoeping (Sweden); Linkoeping University, Department of Medical and Health Sciences (IMH)/Radiology, Linkoeping (Sweden); Brismar, Torkel B. [KUS Huddinge, Department of Clinical Science, Intervention and Technology at Karolinska Institutet and Department of Radiology, Stockholm (Sweden)

    2014-02-15

    Bone strength depends on both mineral content and bone structure. The aim of this in vitro study was to develop a method of quantitatively assessing trabecular bone structure by applying three-dimensional image processing to data acquired with multi-slice and cone-beam computed tomography using micro-computed tomography as a reference. Fifteen bone samples from the radius were examined. After segmentation, quantitative measures of bone volume, trabecular thickness, trabecular separation, trabecular number, trabecular nodes, and trabecular termini were obtained. The clinical machines overestimated bone volume and trabecular thickness and underestimated trabecular nodes and number, but cone-beam CT to a lesser extent. Parameters obtained from cone beam CT were strongly correlated with μCT, with correlation coefficients between 0.93 and 0.98 for all parameters except trabecular termini. The high correlation between cone-beam CT and micro-CT suggest the possibility of quantifying and monitoring changes of trabecular bone microarchitecture in vivo using cone beam CT. (orig.)

  16. The three-dimensional microstructure of trabecular bone: Analysis of site-specific variation in the human jaw bone

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jo Eun; Yi, Won Jin; Heo, Min Suk; Lee, Sam Sun; Choi, Soon Chul; Huh, Kyung Hoe [Dept. of Oral and Maxillofacial Radiology and Dental Research Institute, School of Dentistry, Seoul National University, Seoul (Korea, Republic of); Shin, Jae Myung [Dept. of Oral and Maxillofacial Surgery, Ilsan Paik Hospital, Inje University College of Medicine, Goyang (Korea, Republic of); Oh, Sung Ook [A Plus Dental Clinic, Seoul (Korea, Republic of)

    2013-12-15

    This study was performed to analyze human maxillary and mandibular trabecular bone using the data acquired from micro-computed tomography (micro-CT), and to characterize the site-specific microstructures of trabeculae. Sixty-nine cylindrical bone specimens were prepared from the mandible and maxilla. They were divided into 5 groups by region: the anterior maxilla, posterior maxilla, anterior mandible, posterior mandible, and mandibular condyle. After the specimens were scanned using a micro-CT system, three-dimensional microstructural parameters such as the percent bone volume, bone specific surface, trabecular thickness, trabecular separation, trabecular number, structure model index, and degrees of anisotropy were analyzed. Among the regions other than the condylar area, the anterior mandibular region showed the highest trabecular thickness and the lowest value for the bone specific surface. On the other hand, the posterior maxilla region showed the lowest trabecular thickness and the highest value for the bone specific surface. The degree of anisotropy was lowest at the anterior mandible. The condyle showed thinner trabeculae with a more anisotropic arrangement than the other mandibular regions. There were microstructural differences between the regions of the maxilla and mandible. These results suggested that different mechanisms of external force might exist at each site.

  17. Lacunarity analysis of spatial pattern in CT images of vertebral trabecular bone for assessing osteoporosis.

    Science.gov (United States)

    Dougherty, Geoffrey; Henebry, Geoffrey M

    2002-03-01

    The structural integrity of vertebral trabecular bone is determined by the continuity of its trabecular network and the size of the holes comprising its marrow space, both of which determine the apparent size of the marrow spaces in a transaxial CT image. A model-independent assessment of the trabeculation pattern was determined from the lacunarity of thresholded CT images. Using test images of lumbar vertebrae from human cadavers, acquired at different slice thicknesses, we determined that both median thresholding and local adaptive thresholding (using a 7 x 7 window) successfully segmented the grey-scale images. Lacunarity analysis indicated a multifractal nature to the images, and a range of marrow space sizes with significant structure around 14-18 mm(2). Preliminary studies of in vivo images from a clinical CT scanner indicate that lacunarity analysis can follow the pattern of bone loss in osteoporosis by monitoring the homogeneity of the marrow spaces, which is related to the connectivity of the trabecular bone network and the marrow space sizes. Although the patient sample was small, derived parameters such as the maximum deviation of the lacunarity from a neutral (fractal) model, and the maximum derivative of this deviation, seem to be sufficiently sensitive to distinguish a range of bone conditions. Our results suggest that these parameters, used with bone mineral density values, may have diagnostic value in characterizing osteoporosis and predicting fracture risk.

  18. Does mechanical stimulation really protect the architecture of trabecular bone? A simulation study.

    Science.gov (United States)

    Maurer, Manfred M; Weinkamer, Richard; Müller, Ralph; Ruffoni, Davide

    2015-08-01

    Although it is beyond doubt that mechanical stimulation is crucial to maintain bone mass, its role in preserving bone architecture is much less clear. Commonly, it is assumed that mechanics helps to conserve the trabecular network since an "accidental" thinning of a trabecula due to a resorption event would result in a local increase of load, thereby activating bone deposition there. However, considering that the thin trabecula is part of a network, it is not evident that load concentration happens locally on the weakened trabecula. The aim of this work was to clarify whether mechanical load has a protective role for preserving the trabecular network during remodeling. Trabecular bone is made dynamic by a remodeling algorithm, which results in a thickening/thinning of trabeculae with high/low strain energy density. Our simulations show that larger deviations from a regular cubic lattice result in a greater loss of trabeculae. Around lost trabeculae, the remaining trabeculae are on average thinner. More generally, thin trabeculae are more likely to have thin trabeculae in their neighborhood. The plausible consideration that a thin trabecula concentrates a higher amount of strain energy within itself is therefore only true when considering a single isolated trabecula. Mechano-regulated remodeling within a network-like architecture leads to local concentrations of thin trabeculae.

  19. Bone dosimetry using synthetic images to represent trabecular bones of five regions of the human body

    Energy Technology Data Exchange (ETDEWEB)

    Lima Filho, Jose de M. [Instituto Federal de Educacao, Ciencia e Tecnologia de Pernambuco (IFPE), Recife, PE (Brazil); Vieira, Jose W. [Escola Politecnica de Pernambuco (POLI). Universidade de Pernambuco (UPE), Recife, PE (Brazil); Lima, Vanildo J. de M., E-mail: vjr@ufpe.br [Departamento de Anatomia. Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil); Lima, Lindeval F., E-mail: lindeval@dmat.ufrr.br [Departamento de Matematica (DMAT). Universidade Federal de Roraima (UFRR), Boa Vista, RR (Brazil); Lima, Fernando R.A., E-mail: falima@cnen.gov.br [Centro Regional de Ciencias Nucleares (CRCN/NE-CNEN-PE), Recife, PE (Brazil); Vasconcelos, Wagner E. de [Departamento de Energia Nuclear (DEN). Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil)

    2011-07-01

    One of the greatest challenges in numerical dosimetry of ionizing radiation is to estimate the absorbed dose by bone tissue in the human body. The bone tissues of greater radiosensitivity are the red bone marrow (RBM), that consist of the hematopoietic cells, located within the trabecular bones, and the bone surface cells (BSC), called osteogenic cells. The report 70 of the ICRP lists five spongiosa regions with their respective volume percent of trabecular bone: ribs (also contemplating the clavicles and sternum), spine, long bones, pelvis and skull (also contemplating mandible). The Grupo de Pesquisa em Dosimetria Numerica (GDN/CNPq) has been built exposure computational models (ECMs) based on voxel phantoms and EGSnrc Monte Carlo code. To estimate the energy deposited in the RBM and in the BSC of a phantom, the GDN/CNPq has used a method based on micro-CT images of the five trabecular regions mentioned above. These images were provided by other research institutes and were obtained from scan of bone samples of adult. Here is the greatest difficulty in reproducing this method: besides the need for bone images of real people with micrometer resolution, the distribution of bone marrow in the human body, according to ICRP 70, varies with age. This article presents some proposals of the GDN/CNPQ for replacing in the ECMs the micro-CT images by images synthesized by the computer, based on Monte Carlo sampling. (author)

  20. Effect of low-dose CT and iterative reconstruction on trabecular bone microstructure assessment

    Science.gov (United States)

    Kopp, Felix K.; Baum, Thomas; Nasirudin, Radin A.; Mei, Kai; Garcia, Eduardo G.; Burgkart, Rainer; Rummeny, Ernst J.; Bauer, Jan S.; Noël, Peter B.

    2016-03-01

    The trabecular bone microstructure is an important factor in the development of osteoporosis. It is well known that its deterioration is one effect when osteoporosis occurs. Previous research showed that the analysis of trabecular bone microstructure enables more precise diagnoses of osteoporosis compared to a sole measurement of the mineral density. Microstructure parameters are assessed on volumetric images of the bone acquired either with high-resolution magnetic resonance imaging, high-resolution peripheral quantitative computed tomography or high-resolution computed tomography (CT), with only CT being applicable to the spine, which is one of clinically most relevant fracture sites. However, due to the high radiation exposure for imaging the whole spine these measurements are not applicable in current clinical routine. In this work, twelve vertebrae from three different donors were scanned with standard and low radiation dose. Trabecular bone microstructure parameters were assessed for CT images reconstructed with statistical iterative reconstruction (SIR) and analytical filtered backprojection (FBP). The resulting structure parameters were correlated to the biomechanically determined fracture load of each vertebra. Microstructure parameters assessed for low-dose data reconstructed with SIR significantly correlated with fracture loads as well as parameters assessed for standard-dose data reconstructed with FBP. Ideal results were achieved with low to zero regularization strength yielding microstructure parameters not significantly different from those assessed for standard-dose FPB data. Moreover, in comparison to other approaches, superior noise-resolution trade-offs can be found with the proposed methods.

  1. On estimating the directionality distribution in pedicle trabecular bone from micro-CT images.

    Science.gov (United States)

    Gdyczynski, Catherine M; Manbachi, Amir; Hashemi, SayedMasoud; Lashkari, Bahman; Cobbold, Richard S C

    2014-12-01

    Our interest in the trabecular alignment within bone stems from the need to better understand the manner in which it can affect ultrasound propagation, particularly in pedicles. Within long bones it is well established that trabecular structures are aligned in an organized manner associated with the direction of load distribution; however, for smaller bones there are limited alignment studies. To investigate the directionality distribution in a quantitative manner we used a micro-CT to obtain three-dimensional (3D) structural data and developed analytical methods based on the special properties of Gabor filters. Implementation of these techniques has been developed and tested on a variety of simulated images as well as on 3D structures whose geometry is well-defined. To test the use of this technique we compared the results obtained on vertebral body trabecular bone with visual directionality and previous measurements by others. The method has been applied to six human pedicle samples in two orthogonal planes with results that provide reasonable proof-of-principle evidence that the method is well suited for estimating the directionality distribution within pedicle bones.

  2. Hyalinizing trabecular tumor of the thyroid gland: A puzzling entity on fine needle aspiration cytology

    Directory of Open Access Journals (Sweden)

    Jitendra Nasit

    2014-01-01

    Full Text Available Hyalinizing trabecular tumor (HTT is a rare unique but controversial thyroid neoplasm, characterized by prominent trabecular growth pattern and stromal hyalinization. Whether HTT is a benign tumor or a variant of papillary thyroid carcinoma (PTC is still unclear. Cytology findings of HTT have been described in few reports. Cytological features of HTT frequently overlap with those of PTC and medullary thyroid carcinoma, which can lead to frequent misdiagnosis. In order to avoid overtreatment like total thyroidectomy, pathologist should be aware of cytological features of HTT. We present a case of 35-year-old female with a right-side thyroid swelling for three years. Fine needle aspiration cytology was performed. According to The Bethesda System for Reporting Thyroid Cytopathology, cytological diagnosis of benign thyroid neoplasm was made. Histopathology of the right thyroidectomy specimen showed HTT. Accurate preoperative diagnosis of HTT requires a very meticulous and cautious approach in the evaluation of cytological features. Trabecular pattern of cells, vague curved nuclear palisading, radiating arrangement of cells around hyaline material, spindled to elongated cells, filamentous cytoplasmic processes with ill-defined cell border and yellow bodies are important diagnostic features of HTT. Nuclear features alone are insufficient for the diagnosis of HTT. Any suspicious cytology of thyroid lesion should follow hemithyroidectomy and histopathological evaluation.

  3. Cortical and trabecular bone at the forearm show different adaptation patterns in response to tennis playing.

    Science.gov (United States)

    Ducher, Gaële; Prouteau, Stéphanie; Courteix, Daniel; Benhamou, Claude-Laurent

    2004-01-01

    Bone responds to impact-loading activity by increasing its size and/or density. The aim of this study was to compare the magnitude and modality of the bone response between cortical and trabecular bone in the forearms of tennis players. Bone area, bone mineral content (BMC), and bone mineral density (BMD) of the ulna and radius were measured by dual-energy X-ray absorptiometry (DXA) in 57 players (24.5 +/- 5.7 yr old), at three sites: the ultradistal region (50% trabecular bone), the mid-distal regions, and third-distal (mainly cortical bone). At the ultradistal radius, the side-to-side difference in BMD was larger than in bone area (8.4 +/- 5.2% and 4.9 +/- 4.0%, respectively, p < 0.01). In the cortical sites, the asymmetry was lower (p < 0.01) in BMD than in bone area (mid-distal radius: 4.0 +/- 4.3% vs 11.7 +/- 6.8%; third-distal radius: 5.0 +/- 4.8% vs 8.4 +/- 6.2%). The asymmetry in bone area explained 33% of the variance of the asymmetry in BMC at the ultradistal radius, 66% at the mid-distal radius, and 53% at the third-distal radius. The ulna displayed similar results. Cortical and trabecular bone seem to respond differently to mechanical loading. The first one mainly increases its size, whereas the second one preferentially increases its density.

  4. What Lies Behind NSF Astronomer Demographics? Subjectivities of Women, Minorities and Foreign-born Astronomers within Meshworks of Big Science Astronomy

    Science.gov (United States)

    Guillen, Reynal; Gu, D.; Holbrook, J.; Murillo, L. F.; Traweek, S.

    2011-01-01

    Our current research focuses on the trajectory of scientists working with large-scale databases in astronomy, following them as they strategically build their careers, digital infrastructures, and make their epistemological commitments. We look specifically at how gender, ethnicity, nationality intersect in the process of subject formation in astronomy, as well as in the process of enrolling partners for the construction of instruments, design and implementation of large-scale databases. Work once figured as merely technical support, such assembling data catalogs, or as graphic design, generating pleasing images for public support, has been repositioned at the core of the field. Some have argued that such databases enable a new kind of scientific inquiry based on data exploration, such as the "fourth paradigm" or "data-driven" science. Our preliminary findings based on oral history interviews and ethnography provide insights into meshworks of women, African-American, "Hispanic," Asian-American and foreign-born astronomers. Our preliminary data suggest African-American men are more successful in sustaining astronomy careers than Chicano and Asian-American men. A distinctive theme in our data is the glocal character of meshworks available to and created by foreign-born women astronomers working at US facilities. Other data show that the proportion of Asian to Asian American and foreign-born Latina/o to Chicana/o astronomers is approximately equal. Futhermore, Asians and Latinas/os are represented in significantly greater numbers than Asian Americans and Chicanas/os. Among professional astronomers in the US, each ethnic minority group is numbered on the order of tens, not hundreds. Project support is provided by the NSF EAGER program to University of California, Los Angeles under award 0956589.

  5. Research on Damage in Trabecular Bone of the Healthy Human Acetabulum at Small Strains Using Nonlinear Micro-finite Element Analysis

    Institute of Scientific and Technical Information of China (English)

    DING Hai; ZHU Zhen-nan; DAI Ke-rong; YE Ming; WANG Cheng-tao

    2008-01-01

    The mechanical properties of the pelvic trabecular bone have been studied at the continuum level. However, nothing is known about the tissue-level damage in the trabecular bone of the healthy human acetabulum at apparent small strains characteristic of habitual. By a DAWING 4000 A supercomputer, nonlinear micro-finite element (μFE) analysis was performed to quantify tissue-level damage accumulation in trabecular bone at small strains. The data indicate that damage in trabecular bone commence at 0.2% apparent strain. The findings imply that tissue yielding can initiate at very low strains in the trabecular bone of the healthy acetabulum and that this local failure has negative consequences on the apparent mechanical properties of trabecular bone.

  6. Micro-finite-element method to assess elastic properties of trabecular bone at micro- and macroscopic level.

    Science.gov (United States)

    Rieger, R; Auregan, J C; Hoc, T

    2017-09-08

    The objective of the present study is to assess the mechanical behavior of trabecular bone based on microCT imaging and micro-finite-element analysis. In this way two methods are detailed: (i) direct determination of macroscopic elastic property of trabecular bone; (ii) inverse approach to assess mechanical properties of trabecular bone tissue. Thirty-five females and seven males (forty-two subjects) mean aged (±SD) 80±11.7 years from hospitals of Assistance publique-Hôpitaux de Paris (AP-HP) diagnosed with osteoporosis following a femoral neck fracture due to a fall from standing were included in this study. Fractured heads were collected during hip replacement surgery. Standardized bone cores were removed from the femoral head's equator by a trephine in a water bath. MicroCT images acquisition and analysis were performed with CTan(®) software and bone volume fraction was then determined. Micro-finite-element simulations were per-formed using Abaqus 6.9-2(®) software in order to determine the macroscopic mechanical behaviour of the trabecular bone. After microCT acquisition, a longitudinal compression test was performed and the experimental macroscopic Young's Modulus was extracted. An inverse approach based on the whole trabecular bone's mechanical response and micro-finite-element analysis was performed to determine microscopic mechanical properties of trabecular bone. In the present study, elasticity of the tissue was shown to be similar to that of healthy tissue but with a lower yield stress. Classical histomorphometric analysis form microCT imaging associated with an inverse micro-finite-element method allowed to assess microscopic mechanical trabecular bone parameters. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  7. Effects of estrogen with micronized progesterone on cortical and trabecular bone mass and microstructure in recently postmenopausal women.

    Science.gov (United States)

    Farr, Joshua N; Khosla, Sundeep; Miyabara, Yuko; Miller, Virginia M; Kearns, Ann E

    2013-02-01

    In women, cortical bone mass decreases significantly at menopause. By contrast, loss of trabecular bone begins in the third decade and accelerates after menopause. The aim of the study was to investigate the effects of estrogen on cortical and trabecular bone. The Kronos Early Estrogen Prevention Study is a double-blind, randomized, placebo-controlled trial of menopausal hormone treatment (MHT) in women, enrolled within 6-36 months of their final menstrual period. The study was conducted at the Mayo Clinic, Rochester, Minnesota. Subjects were treated with placebo (n = 31), or .45 mg/d conjugated equine estrogens (n = 20), or transdermal 50 μg/d 17β-estradiol (n = 25) with pulsed micronized progesterone. Cortical and trabecular microarchitecture at the distal radius was assessed by high-resolution peripheral quantitative computed tomography. At the distal radius, cortical volumetric bone mineral density (vBMD) decreased, and cortical porosity increased in the placebo group; MHT prevented these changes. By contrast, MHT did not prevent decreases in trabecular microarchitecture at the radius. However, MHT prevented decreases in trabecular vBMD at the thoracic spine (assessed in a subset of subjects; n = 51). These results indicate that MHT prevents deterioration in radial cortical vBMD and porosity in recently menopausal women. The maintenance of cortical bone in response to estrogen likely has important clinical implications because cortical bone morphology plays an important role in bone strength. However, effects of MHT on trabecular bone at the radius differ from those at the thoracic spine. Underlying mechanisms for these site-specific effects of MHT on cortical vs trabecular bone require further investigation.

  8. Black bear parathyroid hormone has greater anabolic effects on trabecular bone in dystrophin-deficient mice than in wild type mice.

    Science.gov (United States)

    Gray, Sarah K; McGee-Lawrence, Meghan E; Sanders, Jennifer L; Condon, Keith W; Tsai, Chung-Jui; Donahue, Seth W

    2012-09-01

    Duchenne muscular dystrophy (DMD) is an X-linked neuromuscular disease that has deleterious consequences in muscle and bone, leading to decreased mobility, progressive osteoporosis, and premature death. Patients with DMD experience a higher-than-average fracture rate, particularly in the proximal and distal femur and proximal tibia. The dystrophin-deficient mdx mouse is a model of DMD that demonstrates muscle degeneration and fibrosis and osteoporosis. Parathyroid hormone, an effective anabolic agent for post-menopausal and glucocorticoid-induced osteoporosis, has not been explored for DMD. Black bear parathyroid hormone (bbPTH) has been implicated in the maintenance of bone properties during extended periods of disuse (hibernation). We cloned bbPTH and found 9 amino acid residue differences from human PTH. Apoptosis was mitigated and cAMP was activated by bbPTH in osteoblast cultures. We administered 28nmol/kg of bbPTH 1-84 to 4-week old male mdx and wild type mice via daily (5×/week) subcutaneous injection for 6 weeks. Vehicle-treated mdx mice had 44% lower trabecular bone volume fraction than wild type mice. No changes were found in femoral cortical bone geometry or mechanical properties with bbPTH treatment in wild type mice, and only medio-lateral moment of inertia changed with bbPTH treatment in mdx femurs. However, μCT analyses of the trabecular regions of the distal femur and proximal tibia showed marked increases in bone volume fraction with bbPTH treatment, with a greater anabolic response (7-fold increase) in mdx mice than wild type mice (2-fold increase). Trabecular number increased in mdx long bone, but not wild type bone. Additionally, greater osteoblast area and decreased osteoclast area were observed with bbPTH treatment in mdx mice. The heightened response to PTH in mdx bone compared to wild type suggests a link between dystrophin deficiency, altered calcium signaling, and bone. These findings support further investigation of PTH as an anabolic

  9. Evaluation of trabecular structure changes in osteoarthritis of the temporomandibular joint with cone beam computed tomography imaging.

    Science.gov (United States)

    Liang, Xin; Liu, Shuming; Qu, Xingmin; Wang, Zhihui; Zheng, Jianbo; Xie, Xiaoyan; Ma, Guowu; Zhang, Zuyan; Ma, Xuchen

    2017-09-01

    To explore the possibility of using 2-dimensional image assessments in combination with cone beam computed tomography (CBCT) in patients with temporomandibular joint osteoarthritis (TMJOA) to enhance the clinical significance and applicability of the CBCT findings on TMJOA changes. Fifty-two patients with unilateral TMJOA and 40 healthy adults who had undergone CBCT in preparation for orthodontic treatment were selected for this study. Temporomandibular joint images were acquired with CBCT. All images were classified into 4 phases (slight erosion, widespread erosion, appearance of bone maintenance, and partial loss of condylar head with a remodeled cortical surface) and 4 levels of severity (absent, slight, moderate, and extensive). Quantitative microstructural analysis, including bone value fraction (BV/TV), trabecular number (Tb.N), trabecular thickness, and trabecular separation (Tb.Sp) of each image, was performed by using a customized software. In patients with unilateral TMJOA, the affected side had significantly higher BV/TV and Tb.N and significantly lower Tb.Sp compared with the unaffected side. Compared with healthy individuals, the affected joints in patients with TMJOA had significantly higher BV/TV and trabecular thickness and significantly lower Tb.N and Tb.Sp. No significant difference was found among different phase groups or different severity levels. CBCT combined with a software investigation protocol for microstructure measurement can be used to provide reliable trabecular parameters in assessing TMJOA. Copyright © 2017 Elsevier Inc. All rights reserved.

  10. Extraction of 3D Femur Neck Trabecular Bone Architecture from Clinical CT Images in Osteoporotic Evaluation: a Novel Framework.

    Science.gov (United States)

    Sapthagirivasan, V; Anburajan, M; Janarthanam, S

    2015-08-01

    The early detection of osteoporosis risk enhances the lifespan and quality of life of an individual. A reasonable in-vivo assessment of trabecular bone strength at the proximal femur helps to evaluate the fracture risk and henceforth, to understand the associated structural dynamics on occurrence of osteoporosis. The main aim of our study was to develop a framework to automatically determine the trabecular bone strength from clinical femur CT images and thereby to estimate its correlation with BMD. All the 50 studied south Indian female subjects aged 30 to 80 years underwent CT and DXA measurements at right femur region. Initially, the original CT slices were intensified and active contour model was utilised for the extraction of the neck region. After processing through a novel process called trabecular enrichment approach (TEA), the three dimensional (3D) trabecular features were extracted. The extracted 3D trabecular features, such as volume fraction (VF), solidity of delta points (SDP) and boundness, demonstrated a significant correlation with femoral neck bone mineral density (r = 0.551, r = 0.432, r = 0.552 respectively) at p TEA method would be useful for spotting women vulnerable to osteoporotic risk.

  11. Wavelet based characterization of ex vivo vertebral trabecular bone structure with 3T MRI compared to microCT

    Energy Technology Data Exchange (ETDEWEB)

    Krug, R; Carballido-Gamio, J; Burghardt, A; Haase, S; Sedat, J W; Moss, W C; Majumdar, S

    2005-04-11

    Trabecular bone structure and bone density contribute to the strength of bone and are important in the study of osteoporosis. Wavelets are a powerful tool to characterize and quantify texture in an image. In this study the thickness of trabecular bone was analyzed in 8 cylindrical cores of the vertebral spine. Images were obtained from 3 Tesla (T) magnetic resonance imaging (MRI) and micro-computed tomography ({micro}CT). Results from the wavelet based analysis of trabecular bone were compared with standard two-dimensional structural parameters (analogous to bone histomorphometry) obtained using mean intercept length (MR images) and direct 3D distance transformation methods ({micro}CT images). Additionally, the bone volume fraction was determined from MR images. We conclude that the wavelet based analyses delivers comparable results to the established MR histomorphometric measurements. The average deviation in trabecular thickness was less than one pixel size between the wavelet and the standard approach for both MR and {micro}CT analysis. Since the wavelet based method is less sensitive to image noise, we see an advantage of wavelet analysis of trabecular bone for MR imaging when going to higher resolution.

  12. Uniaxial and Multiaxial Fatigue Life Prediction of the Trabecular Bone Based on Physiological Loading: A Comparative Study.

    Science.gov (United States)

    Fatihhi, S J; Harun, M N; Abdul Kadir, Mohammed Rafiq; Abdullah, Jaafar; Kamarul, T; Öchsner, Andreas; Syahrom, Ardiyansyah

    2015-10-01

    Fatigue assessment of the trabecular bone has been developed to give a better understanding of bone properties. While most fatigue studies are relying on uniaxial compressive load as the method of assessment, in various cases details are missing, or the uniaxial results are not very realistic. In this paper, the effect of three different load histories from physiological loading applied on the trabecular bone were studied in order to predict the first failure surface and the fatigue lifetime. The fatigue behaviour of the trabecular bone under uniaxial load was compared to that of multiaxial load using a finite element simulation. The plastic strain was found localized at the trabecular structure under multiaxial load. On average, applying multiaxial loads reduced more than five times the fatigue life of the trabecular bone. The results provide evidence that multiaxial loading is dominated in the low cycle fatigue in contrast to the uniaxial one. Both bone volume fraction and structural model index were best predictors of failure (p < 0.05) in fatigue for both types of loading, whilst uniaxial loading has indicated better values in most cases.

  13. Effects of different types of jump impact on trabecular bone mass and microarchitecture in growing rats.

    Directory of Open Access Journals (Sweden)

    Yong-In Ju

    Full Text Available Substantial evidence from animal studies indicates that jumping increases bone mass and strength. However, most studies have focused on the take-off, rather than the landing phase of jumps. Thus, we compared the effects of landing and upward jump impact on trabecular bone mass and microarchitecture. Male Wistar rats aged 10 weeks were randomly assigned to the following groups: sedentary control (CON, 40-cm upward jumps (40UJ; 40-cm drop jumps (40DJ; and 60-cm drop jumps (60DJ (n = 10 each. The upward jump protocol comprised 10 upward jumps/day, 5 days/week for 8 weeks to a height of 40 cm. The drop jump protocol comprised dropping rats from a height of 40 or 60 cm at the same frequency and time period as the 40UJ group. Trabecular bone mass, architecture, and mineralization at the distal femoral metaphysis were evaluated using microcomputed tomography. Ground reaction force (GRF was measured using a force platform. Bone mass was significantly higher in the 40UJ group compared with the DJ groups (+49.1% and +28.3%, respectively, although peak GRF (-57.8% and -122.7%, respectively and unit time force (-21.6% and -36.2%, respectively were significantly lower in the 40UJ group. These results showed that trabecular bone mass in growing rats is increased more effectively by the take-off than by the landing phases of jumps and suggest that mechanical stress accompanied by muscle contraction would be more important than GRF as an osteogenic stimulus. However, the relevance of these findings to human bone physiology is unclear and requires further study.

  14. Trabecular reorganization in consecutive iliac crest biopsies when switching from bisphosphonate to strontium ranelate treatment.

    Directory of Open Access Journals (Sweden)

    Björn Jobke

    Full Text Available BACKGROUND: Several agents are available to treat osteoporosis while addressing patient-specific medical needs. Individuals' residual risk to severe fracture may require changes in treatment strategy. Data at osseous cellular and microstructural levels due to a therapy switch between agents with different modes of action are rare. Our study on a series of five consecutively taken bone biopsies from an osteoporotic individual over a six-year period analyzes changes in cellular characteristics, bone microstructure and mineralization caused by a therapy switch from an antiresorptive (bisphosphonate to a dual action bone agent (strontium ranelate. METHODOLOGY/PRINCIPAL FINDINGS: Biopsies were progressively taken from the iliac crest of a female patient. Four biopsies were taken during bisphosphonate therapy and one biopsy was taken after one year of strontium ranelate (SR treatment. Furthermore, serum bone markers and dual x-ray absorptiometry measurements were acquired. Undecalcified histology was used to assess osteoid parameters and bone turnover. Structural indices and degree of mineralization were determined using microcomputed tomography, quantitative backscattered electron imaging, and combined energy dispersive x-ray/µ-x-ray-fluorescence microanalysis. CONCLUSIONS/SIGNIFICANCE: Microstructural data revealed a notable increase in bone volume fraction after one year of SR treatment compared to the bisphosphonate treatment period. Indices of connectivity density, structure model index and trabecular bone pattern factor were predominantly enhanced indicating that the architectural transformation from trabecular rods to plates was responsible for the bone volume increase and less due to changes in trabecular thickness and number. Administration of SR following bisphosphonates led to a maintained mineralization profile with an uptake of strontium on the bone surface level. Reactivated osteoclasts designed tunneling, hook-like intratrabecular

  15. The development of osteoporosis detective analysis method in trabecular condylus of menopause women using panoramic radiograph

    Directory of Open Access Journals (Sweden)

    Azhari Azhari

    2016-08-01

    Full Text Available Osteoporosis incidence in Indonesia increase each year, 1 of 3 menopause women suspected have osteoporosis, then earlier detection is needed. Factors that influence the successful analysis is the choice of region of interset (ROI and extract feature method. The purpose of this research is to determine the best method to define the bone quality based on trabecular of condylus analysis. Data were obtained from Dentistry Hospital, Padjadjaran University Bandung. Research were conducted cross-section to 79 samples which measured in dual energy X-ray absorbsimetry (DEXA as a base standard then taken its panoramic radiograph. Trabecular analysis was conducted in ROI of condylus using panoramic radiograph then cursor was clicked in cortical endorsal following the condylus head shape. To reduce the noise, we conducted pre-processing by compensational method, it is a finding of the lowest means of variant number around condylus as a reduce factor then affect the radiograph of condylus become darker. Background sets in zero (0 meanwhile trabecular stay at gray scale. Feature extraction applied 3 analytical methods, they are: gray level co accurance matrix (GLCM, histogram and fraction. Statistical analysis shows T-score DEXA correlation with 3 methods, proofed that fraction method performed the best correlation which r value is 0.377and GLCM (contrast r=0.233, correlation =0.342, energy -0.147, homogenity= r =-0.107, meanwhile histogram (max histogram r=0.253, range histogram r=0.06. As a conclusion, fraction method with ROI of condylus head shape is the best method to determine osteoporosis in post menopause women.

  16. The quartic piecewise-linear criterion for the multiaxial yield behavior of human trabecular bone.

    Science.gov (United States)

    Sanyal, Arnav; Scheffelin, Joanna; Keaveny, Tony M

    2015-01-01

    Prior multiaxial strength studies on trabecular bone have either not addressed large variations in bone volume fraction and microarchitecture, or have not addressed the full range of multiaxial stress states. Addressing these limitations, we utilized micro-computed tomography (lCT) based nonlinear finite element analysis to investigate the complete 3D multiaxial failure behavior of ten specimens (5mm cube) of human trabecular bone, taken from three anatomic sites and spanning a wide range of bone volume fraction (0.09–0.36),mechanical anisotropy (range of E3/E1¼3.0–12.0), and microarchitecture. We found that most of the observed variation in multiaxial strength behavior could be accounted for by normalizing the multiaxial strength by specimen-specific values of uniaxial strength (tension,compression in the longitudinal and transverse directions). Scatter between specimens was reduced further when the normalized multiaxial strength was described in strain space.The resulting multiaxial failure envelope in this normalized-strain space had a rectangular boxlike shape for normal–normal loading and either a rhomboidal box like shape or a triangular shape for normal-shear loading, depending on the loading direction. The finite element data were well described by a single quartic yield criterion in the 6D normalized strain space combined with a piecewise linear yield criterion in two planes for normalshear loading (mean error SD: 4.660.8% for the finite element data versus the criterion).This multiaxial yield criterion in normalized-strain space can be used to describe the complete 3D multiaxial failure behavior of human trabecular bone across a wide range of bone volume fraction, mechanical anisotropy, and microarchitecture.

  17. Assessment of Fat distribution and Bone quality with Trabecular Bone Score (TBS) in Healthy Chinese Men

    OpenAIRE

    Shan Lv; Aisen Zhang; Wenjuan Di; Yunlu Sheng; Peng Cheng; Hanmei Qi; Juan Liu; Jing Yu; Guoxian Ding; Jinmei Cai; Bin Lai

    2016-01-01

    Whether fat is beneficial or detrimental to bones is still controversial, which may be due to inequivalence of the fat mass. Our objective is to define the effect of body fat and its distribution on bone quality in healthy Chinese men. A total of 228 men, aged from 38 to 89 years, were recruited. BMD, trabecular bone score (TBS), and body fat distribution were measured by dual-energy X-ray absorptiometry. Subcutaneous and visceral fat were assessed by MRI. In the Pearson correlation analysis,...

  18. 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

    quantification of structure model type, such as plate, rod objects, or mixture of plates or rods. Trabecular thickness is calculated directly from 3-D images, which is especially important for an a priori unknown or changing structure. Furthermore, 2-D trabecular thickness was also calculated based on the plate......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...

  19. Cortical and trabecular bone benefits of mechanical loading are maintained long-term in mice independent of ovariectomy

    Science.gov (United States)

    Warden, Stuart J.; Galley, Matthew R.; Hurd, Andrea L.; Richard, Jeffrey S.; George, Lydia A.; Guildenbecher, Elizabeth A.; Barker, Rick G.; Fuchs, Robyn K.

    2014-01-01

    Skeletal loading enhances cortical and trabecular bone properties. How long these benefits last following loading cessation remains an unresolved, clinically-relevant question. This study investigated long-term maintenance of loading-induced cortical and trabecular bone benefits in female C57BL/6 mice and the influence of a surgically-induced menopause on the maintenance. 16-week-old animals had their right tibia extrinsically loaded 3 days/week for 4 weeks using the mouse tibial axial compression loading model. Left tibias were not loaded and served as internal controls. Animals were subsequently detrained (restricted to cage activities) for 0, 4, 8, 26 or 52 weeks, with ovariectomy (OVX) or sham-OVX surgery being performed at 0 weeks detraining. Loading increased midshaft tibia cortical bone mass, size and strength, and proximal tibia bone volume fraction. The cortical bone mass, area and thickness benefits of loading were lost by 26 weeks of detraining due to heightened medullary expansion. However, loading-induced benefits on bone total area and strength were maintained at each detraining time point. Similarly, the benefits of loading on bone volume fraction persisted at all detraining time points. The long-term benefits of loading on both cortical and trabecular bone were not influenced by a surgically-induced menopause as there were no interactions between loading and surgery. However, OVX had independent effects on cortical bone properties at early (4 and 8 weeks) detraining time points and trabecular bone properties at all detraining time points. These cumulative data indicate loading has long-term benefits on cortical bone size and strength (but not mass) and trabecular bone morphology which are not influenced by a surgically-induced menopause. This suggests skeletal loading associated with physical activity may provide long-term benefits by preparing the skeleton to offset both the cortical and trabecular bone changes associated with aging and menopause

  20. Multi-Elemental Profiling of Tibial and Maxillary Trabecular Bone in Ovariectomised Rats.

    Science.gov (United States)

    Han, Pingping; Lu, Shifeier; Zhou, Yinghong; Moromizato, Karine; Du, Zhibin; Friis, Thor; Xiao, Yin

    2016-01-01

    Atomic minerals are the smallest components of bone and the content of Ca, being the most abundant mineral in bone, correlates strongly with the risk of osteoporosis. Postmenopausal women have a far greater risk of suffering from OP due to low Ca concentrations in their bones and this is associated with low bone mass and higher bone fracture rates. However, bone strength is determined not only by Ca level, but also a number of metallic and non-metallic elements in bone. Thus, in this study, the difference of metallic and non-metallic elements in ovariectomy-induced osteoporosis tibial and maxillary trabecular bone was investigated in comparison with sham operated normal bone by laser ablation inductively-coupled plasma mass spectrometry using a rat model. The results demonstrated that the average concentrations of (25)Mg, (28)Si, (39)K, (47)Ti, (56)Fe, (59)Co, (77)Se, (88)Sr, (137)Ba, and (208)Pb were generally higher in tibia than those in maxilla. Compared with the sham group, Ovariectomy induced more significant changes of these elements in tibia than maxilla, indicating tibial trabecular bones are more sensitive to changes of circulating estrogen. In addition, the concentrations of (28)Si, (77)Se, (208)Pb, and Ca/P ratios were higher in tibia and maxilla in ovariectomised rats than those in normal bone at all time-points. The present study indicates that ovariectomy could significantly impact the element distribution and concentrations between tibia and maxilla.

  1. Relationship between the morphologic features of alveolar trabecular bone and systemic osteoporosis

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Chang Jin; Chang, Hoon Sang; Lee, Byung Do [Wonkwang University College of Medicine, Iksan (Korea, Republic of)

    2005-09-15

    The purpose of this study was to investigate the preliminary use of morphologic operation (MO) in analyzing trabecular pattern of alveolar bone for the predicting systemic osteoporosis. Study subjects consisted of 35 females (average age 48.5 years) and 25 males (average age 25.8 years). Bone mineral density BMD (grams/cm) of lumbar spine and proximal femur of these subjects were measured by a dual energy X-ray absorptiometry (DEXA). Regions of interest (ROIs) were selected from the digitized peri apical radiographs of subjects' posterior jaw. A custom computer program processed morphology operations of ROIs. We compared mean values of 11 MO variables according to the osteoporotic group divided by the T-scores of DEXA. We also studied correlation between radiographic density and these MO variables. The mean radiographic densities insignificantly correlated with MO variables. There were statistically significant differences among the values of 9 MO variables according to the osteoporotic group. Morphologic operation can be effective in analyzing trabecular pattern of alveolar bone for the predicting osteoporosis.

  2. Use of a trabecular metal implant in ankle arthrodesis after failed total ankle replacement

    Science.gov (United States)

    2010-01-01

    Background and purpose Arthrodesis after failed total ankle replacement is complicated and delayed union, nonunion, and shortening of the leg often occur—especially with large bone defects. We investigated the use of a trabecular metal implant and a retrograde intramedullary nail to obtain fusion. Patients and methods 13 patients with a migrated or loose total ankle implant underwent arthrodesis with the use of a retrograde intramedullary nail through a trabecular metal Tibial Cone. The mean follow-up time was 1.4 (0.6–3.4) years. Results At the last examination, 7 patients were pain-free, while 5 had some residual pain but were satisfied with the procedure. 1 patient was dissatisfied and experienced pain and swelling when walking. The implant-bone interfaces showed no radiographic zones or gaps in any patient, indicating union. Interpretation The method is a new way of simplifying and overcoming some of the problems of performing arthrodesis after failed total ankle replacement. PMID:21067435

  3. Estimating the mechanical competence parameter of the trabecular bone: a neural network approach

    Directory of Open Access Journals (Sweden)

    Érica Regina Filletti

    Full Text Available Abstract Introduction The mechanical competence parameter (MCP of the trabecular bone is a parameter that merges the volume fraction, connectivity, tortuosity and Young modulus of elasticity, to provide a single measure of the trabecular bone structural quality. Methods As the MCP is estimated for 3D images and the Young modulus simulations are quite consuming, in this paper, an alternative approach to estimate the MCP based on artificial neural network (ANN is discussed considering as the training set a group of 23 in vitro vertebrae and 12 distal radius samples obtained by microcomputed tomography (μCT, and 83 in vivo distal radius magnetic resonance image samples (MRI. Results It is shown that the ANN was able to predict with very high accuracy the MCP for 29 new samples, being 6 vertebrae and 3 distal radius bones by μCT and 20 distal radius bone by MRI. Conclusion There is a strong correlation (R2 = 0.97 between both techniques and, despite the small number of testing samples, the Bland-Altman analysis shows that ANN is within the limits of agreement to estimate the MCP.

  4. Crohn’s disease and Trabecular Metal implants: a report of two cases and literature review

    Directory of Open Access Journals (Sweden)

    C. Peron

    2015-10-01

    Full Text Available Aim The aim of the present study was to report two cases with Crohn’s disease in whom dental implants successfully osseointegrated and remained functionally stable up to 13 and 12 months of follow-up, respectively. Cases presentation In cases 1 (age 35 years and 2 (age 36 years, tooth 24 and 14, respectively, were atraumatically extracted and a particulated bone grafting material (buccal and palatal aspect of the defect and a Trabecular Metal implant (11.5 mm length, 4.7 mm diameter were inserted in each extraction socket. After implant placement and abutment connection with the final torque (25 Ncm, the provisional restoration was adapted in the oral cavity creating the emergence profile. The provisional crown was screw-retained and had slight occlusal contacts in the centric occlusion (intercuspation position. A periapical radiograph was taken as a control radiograph at the baseline. Postoperatively, antibiotics were prescribed as well as analgesics and an oral rinse was recommended. In both cases, the provisional restoration was removed after 2 weeks and replaced with a full ceramic restoration. Case-1 and case-2 were followed up after 13 months and 12 months respectively. In both cases postoperative healing was uneventful and radiographs taken at follow-up showed no evidence of crestal bone loss. Implants in both cases demonstrated an excellent clinical condition at follow-up. Conclusion Trabecular Metal implants can osseointegrate and remain functionally stable in patients with Crohn’s disease.

  5. Assessment of trabecular bone changes around endosseous implants using image analysis techniques: A preliminary study

    Energy Technology Data Exchange (ETDEWEB)

    Zuki, Mervet El [Dept. of Oral Medicine and Radiology, Benghazi University College of Dentistry, Benghazi (Libya); Omami, Galal [Oral Diagnosis and Polyclinics, Faculty of Dentistry, The University of Hong Kong (Hong Kong); Horner, Keith [Dept. of Oral Radiology, University Dental Hospital of Manchester, Manchester (United Kingdom)

    2014-06-15

    The objective of this study was to assess the trabecular bone changes that occurred around functional endosseous dental implants by means of radiographic image analysis techniques. Immediate preoperative and postoperative periapical radiographs of de-identified implant patients at the University Dental Hospital of Manchester were retrieved, screened for specific inclusion criteria, digitized, and quantified for structural elements of the trabecular bone around the endosseous implants, by using image analysis techniques. Data were analyzed using SPSS version 11.5. P values of less than 0.05 were considered statistically significant. A total of 12 implants from 11 patients were selected for the study, and 26 regions of interest were obtained. There was a significant increase in the bone area in terms of the mean distance between nodes (p=0.006) and a significant decrease in the marrow area in terms of the bone area (p=0.006) and the length of marrow spaces (p=0.032). It appeared that the bone around the implant underwent remodeling that resulted in a net increase in bone after implant placement.

  6. 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 GLCM feature correlation also significantly outperformed MDCTmeasured mean BMD (RMSE = 1.11 ± 0.17) (pGLCM-derived texture features.

  7. Multi-Elemental Profiling of Tibial and Maxillary Trabecular Bone in Ovariectomised Rats

    Directory of Open Access Journals (Sweden)

    Pingping Han

    2016-06-01

    Full Text Available Atomic minerals are the smallest components of bone and the content of Ca, being the most abundant mineral in bone, correlates strongly with the risk of osteoporosis. Postmenopausal women have a far greater risk of suffering from OP due to low Ca concentrations in their bones and this is associated with low bone mass and higher bone fracture rates. However, bone strength is determined not only by Ca level, but also a number of metallic and non-metallic elements in bone. Thus, in this study, the difference of metallic and non-metallic elements in ovariectomy-induced osteoporosis tibial and maxillary trabecular bone was investigated in comparison with sham operated normal bone by laser ablation inductively-coupled plasma mass spectrometry using a rat model. The results demonstrated that the average concentrations of 25Mg, 28Si, 39K, 47Ti, 56Fe, 59Co, 77Se, 88Sr, 137Ba, and 208Pb were generally higher in tibia than those in maxilla. Compared with the sham group, Ovariectomy induced more significant changes of these elements in tibia than maxilla, indicating tibial trabecular bones are more sensitive to changes of circulating estrogen. In addition, the concentrations of 28Si, 77Se, 208Pb, and Ca/P ratios were higher in tibia and maxilla in ovariectomised rats than those in normal bone at all time-points. The present study indicates that ovariectomy could significantly impact the element distribution and concentrations between tibia and maxilla.

  8. Micro-CT characterization of human trabecular bone in osteogenesis imperfecta

    Science.gov (United States)

    Jameson, John; Albert, Carolyne; Smith, Peter; Molthen, Robert; Harris, Gerald

    2011-03-01

    Osteogenesis imperfecta (OI) is a genetic syndrome affecting collagen synthesis and assembly. Its symptoms vary widely but commonly include bone fragility, reduced stature, and bone deformity. Because of the small size and paucity of human specimens, there is a lack of biomechanical data for OI bone. Most literature has focused on histomorphometric analyses, which rely on assumptions to extrapolate 3-D properties. In this study, a micro-computed tomography (μCT) system was used to directly measure structural and mineral properties in pediatric OI bone collected during routine surgical procedures. Surface renderings suggested a poorly organized, plate-like orientation. Patients with a history of bone-augmenting drugs exhibited increased bone volume fraction (BV/TV), trabecular number (Tb.N), and connectivity density (Eu.Conn.D). The latter two parameters appeared to be related to OI severity. Structural results were consistently higher than those reported in a previous histomorphometric study, but these differences can be attributed to factors such as specimen collection site, drug therapy, and assumptions associated with histomorphometry. Mineral testing revealed strong correlations with several structural parameters, highlighting the importance of a dual approach in trabecular bone testing. This study reports some of the first quantitative μCT data of human OI bone, and it suggests compelling possibilities for the future of OI bone assessment.

  9. Trabecular architecture of the manual elements reflects locomotor patterns in primates.

    Science.gov (United States)

    Matarazzo, Stacey A

    2015-01-01

    The morphology of trabecular bone has proven sensitive to loading patterns in the long bones and metacarpal heads of primates. It is expected that we should also see differences in the manual digits of primates that practice different methods of locomotion. Primate proximal and middle phalanges are load-bearing elements that are held in different postures and experience different mechanical strains during suspension, quadrupedalism, and knuckle walking. Micro CT scans of the middle phalanx, proximal phalanx and the metacarpal head of the third ray were used to examine the pattern of trabecular orientation in Pan, Gorilla, Pongo, Hylobates and Macaca. Several zones, i.e., the proximal ends of both phalanges and the metacarpal heads, were capable of distinguishing between knuckle-walking, quadrupedal, and suspensory primates. Orientation and shape seem to be the primary distinguishing factors but differences in bone volume, isotropy index, and degree of anisotropy were seen across included taxa. Suspensory primates show primarily proximodistal alignment in all zones, and quadrupeds more palmar-dorsal orientation in several zones. Knuckle walkers are characterized by having proximodistal alignment in the proximal ends of the phalanges and a palmar-dorsal alignment in the distal ends and metacarpal heads. These structural differences may be used to infer locmotor propensities of extinct primate taxa.

  10. Implant design and its effects on osseointegration over time within cortical and trabecular bone.

    Science.gov (United States)

    Beutel, Bryan G; Danna, Natalie R; Granato, Rodrigo; Bonfante, Estevam A; Marin, Charles; Tovar, Nick; Suzuki, Marcelo; Coelho, Paulo G

    2016-08-01

    Healing chambers present at the interface between implant and bone have become a target for improving osseointegration. The objective of the present study was to compare osseointegration of several implant healing chamber configurations at early time points and regions of interest within bone using an in vivo animal femur model. Six implants, each with a different healing chamber configuration, were surgically implanted into each femur of six skeletally mature beagle dogs (n = 12 implants per dog, total n = 72). The implants were harvested at 3 and 5 weeks post-implantation, non-decalcified processed to slides, and underwent histomorphometry with measurement of bone-to-implant contact (BIC) and bone area fraction occupied (BAFO) within healing chambers at both cortical and trabecular bone sites. Microscopy demonstrated predominantly woven bone at 3 weeks and initial replacement of woven bone by lamellar bone by 5 weeks. BIC and BAFO were both significantly increased by 5 weeks (p < 0.001), and significantly higher in cortical than trabecular bone (p < 0.001). The trapezoidal healing chamber design demonstrated a higher BIC than other configurations. Overall, a strong temporal and region-specific dependence of implant osseointegration in femurs was noted. Moreover, the findings suggest that a trapezoidal healing chamber configuration may facilitate the best osseointegration. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1091-1097, 2016.

  11. Trabecular architecture of the manual elements reflects locomotor patterns in primates.

    Directory of Open Access Journals (Sweden)

    Stacey A Matarazzo

    Full Text Available The morphology of trabecular bone has proven sensitive to loading patterns in the long bones and metacarpal heads of primates. It is expected that we should also see differences in the manual digits of primates that practice different methods of locomotion. Primate proximal and middle phalanges are load-bearing elements that are held in different postures and experience different mechanical strains during suspension, quadrupedalism, and knuckle walking. Micro CT scans of the middle phalanx, proximal phalanx and the metacarpal head of the third ray were used to examine the pattern of trabecular orientation in Pan, Gorilla, Pongo, Hylobates and Macaca. Several zones, i.e., the proximal ends of both phalanges and the metacarpal heads, were capable of distinguishing between knuckle-walking, quadrupedal, and suspensory primates. Orientation and shape seem to be the primary distinguishing factors but differences in bone volume, isotropy index, and degree of anisotropy were seen across included taxa. Suspensory primates show primarily proximodistal alignment in all zones, and quadrupeds more palmar-dorsal orientation in several zones. Knuckle walkers are characterized by having proximodistal alignment in the proximal ends of the phalanges and a palmar-dorsal alignment in the distal ends and metacarpal heads. These structural differences may be used to infer locmotor propensities of extinct primate taxa.

  12. Trabecular evidence for a human-like gait in Australopithecus africanus.

    Directory of Open Access Journals (Sweden)

    Meir M Barak

    Full Text Available Although the earliest known hominins were apparently upright bipeds, there has been mixed evidence whether particular species of hominins including those in the genus Australopithecus walked with relatively extended hips, knees and ankles like modern humans, or with more flexed lower limb joints like apes when bipedal. Here we demonstrate in chimpanzees and humans a highly predictable and sensitive relationship between the orientation of the ankle joint during loading and the principal orientation of trabecular bone struts in the distal tibia that function to withstand compressive forces within the joint. Analyses of the orientation of these struts using microCT scans in a sample of fossil tibiae from the site of Sterkfontein, of which two are assigned to Australopithecus africanus, indicate that these hominins primarily loaded their ankles in a relatively extended posture like modern humans and unlike chimpanzees. In other respects, however, trabecular properties in Au africanus are distinctive, with values that mostly fall between those of chimpanzees and humans. These results indicate that Au. africanus, like Homo, walked with an efficient, extended lower limb.

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

    Science.gov (United States)

    Marwan, Norbert; Kurths, Jürgen; Thomsen, Jesper Skovhus; Felsenberg, Dieter; Saparin, Peter

    2009-02-01

    The study of pathological changes of bone is an important task in diagnostic procedures of patients with metabolic bone diseases such as osteoporosis as well as in monitoring the health state of astronauts during long-term space flights. The recent availability of high-resolution three-dimensional (3D) imaging of bone challenges the development of data analysis techniques able to assess changes of the 3D microarchitecture of trabecular bone. We introduce an approach based on spatial geometrical properties and define structural measures of complexity for 3D image analysis. These measures 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 (microCT) 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 composition of bone, which were not revealed by the static histomorphometry. Finally, we have studied the dependency of the developed measures of complexity on the spatial resolution of the microCT data sets.

  14. Treatment of acromegaly increases BMD but reduces trabecular bone score: a longitudinal study.

    Science.gov (United States)

    Godang, Kristin; Olarescu, Nicoleta Cristina; Bollerslev, Jens; Heck, Ansgar

    2016-08-01

    Bone turnover is increased in acromegaly. Despite normalization of bone turnover after treatment, the risk for vertebral fractures remains increased. Gonadal status, but not BMD, is correlated with vertebral fractures. Trabecular bone score (TBS) is related to bone microarchitecture. The aim of this study is to assess the longitudinal change in TBS and BMD following treatment for acromegaly. DESIGN, SETTING, PATIENTS, INTERVENTIONS, AND MAIN OUTCOME MEASURES: This longitudinal study included 48 patients with acromegaly between 2005 and 2015. BMD, TBS, and markers for bone turnover (P1NP and CTX-1) were measured at baseline and following treatment. Following treatment, the mean TBS decreased by 3.0 (±7.0) %, whereas the BMD at the lumbar spine (LS) increased by 3.2 (±4.9) % (both Pacromegaly affects TBS and BMD at LS in different manners. The reduction of bone turnover markers predicts the increase in BMD but not the decrease in TBS. The DXA changes were more pronounced in men. Alterations in trabecular bone architecture may explain the persistent fracture risk despite the increase in BMD after disease control. © 2016 European Society of Endocrinology.

  15. Simplified inverse filter tracking algorithm for estimating the mean trabecular bone spacing.

    Science.gov (United States)

    Huang, Kai; Ta, Dean; Wang, Weiqi; Le, L H

    2008-07-01

    Ultrasonic backscatter signals provide useful information relevant to bone tissue characterization. Trabecular bone microstructures have been considered as quasi-periodic tissues with a collection of regular and diffuse scatterers. This paper investigates the potential of a novel technique using a simplified inverse filter tracking (SIFT) algorithm to estimate mean trabecular bone spacing (MTBS) from ultrasonic backscatter signals. In contrast to other frequency-based methods, the SIFT algorithm is a time-based method and utilizes the amplitude and phase information of backscatter echoes, thus retaining the advantages of both the autocorrelation and the cepstral analysis techniques. The SIFT algorithm was applied to backscatter signals from simulations, phantoms, and bovine trabeculae in vitro. The estimated MTBS results were compared with those of the autoregressive (AR) cepstrum and quadratic transformation (QT) . The SIFT estimates are better than the AR cepstrum estimates and are comparable with the QT values. The study demonstrates that the SIFT algorithm has the potential to be a reliable and robust method for the estimation of MTBS in the presence of a small signal-to-noise ratio, a large spacing variation between regular scatterers, and a large scattering strength ratio of diffuse scatterers to regular ones.

  16. On the relationship of ultrasonic properties to density and architecture in trabecular bone

    Science.gov (United States)

    Nicholson, Patrick; Bouxsein, Mary

    2002-05-01

    As previously reported elsewhere, we have made ultrasonic measurements in human trabecular bone and have explored relationships with microstructural properties, the latter derived from microcomputed tomography. However, multicollinearity in these data means that conventional regression analysis cannot reliably identify the underlying causal relationships. In an effort to move beyond such limitations, we used our experimental data to test some models of possible interactions between ultrasound and bone. In particular, we compared several models for predicting acoustic velocity in two-phase media as a function of the bone volume fraction. We found good agreement only with the theory of Kuster and Toksoz [Geophysics 39, 587 (1974)] based on scattering by an effective medium. Turning our attention to attenuation, we examined relationships with trabecular thickness (Tb.Th) and the number of trabeculae per unit volume (Tb.N). The exponent relating attenuation to Tb.Th was 3.2, lower than the value of 4 predicted for long wavelength inelastic scattering by cylinders. This may be due to multiple scattering, since restricting the analysis to specimens with relatively low Tb.N yielded an exponent of 3.9. The exponent relating attenuation to Tb.N was 1.3, higher than the expected value of unity, which may again reflect the influence of multiple scattering.

  17. Computational modelling of the mechanics of trabecular bone and marrow using fluid structure interaction techniques.

    Science.gov (United States)

    Birmingham, E; Grogan, J A; Niebur, G L; McNamara, L M; McHugh, P E

    2013-04-01

    Bone marrow found within the porous structure of trabecular bone provides a specialized environment for numerous cell types, including mesenchymal stem cells (MSCs). Studies have sought to characterize the mechanical environment imposed on MSCs, however, a particular challenge is that marrow displays the characteristics of a fluid, while surrounded by bone that is subject to deformation, and previous experimental and computational studies have been unable to fully capture the resulting complex mechanical environment. The objective of this study was to develop a fluid structure interaction (FSI) model of trabecular bone and marrow to predict the mechanical environment of MSCs in vivo and to examine how this environment changes during osteoporosis. An idealized repeating unit was used to compare FSI techniques to a computational fluid dynamics only approach. These techniques were used to determine the effect of lower bone mass and different marrow viscosities, representative of osteoporosis, on the shear stress generated within bone marrow. Results report that shear stresses generated within bone marrow under physiological loading conditions are within the range known to stimulate a mechanobiological response in MSCs in vitro. Additionally, lower bone mass leads to an increase in the shear stress generated within the marrow, while a decrease in bone marrow viscosity reduces this generated shear stress.

  18. Neocellularization and neovascularization of nanosized bioactive glass-coated decellularized trabecular bone scaffolds

    KAUST Repository

    Gerhardt, Lutz Christian

    2012-09-11

    In this study, the in vivo recellularization and neovascularization of nanosized bioactive glass (n-BG)-coated decellu-larized trabecular bone scaffolds were studied in a rat model and quantified using stereological analyses. Based on the highest amount of vascular endothelial growth factor (VEGF) secreted by human fibroblasts grown on n-BG coatings (0-1.245 mg/cm 2), decellularized trabecular bone samples (porosity: 43-81%) were coated with n-BG particles. Grown on n-BG particles at a coating density of 0.263 mg/cm2, human fibroblasts produced 4.3 times more VEGF than on uncoated controls. After 8 weeks of implantation in Sprague-Dawley rats, both uncoated and n-BG-coated samples were well infiltrated with newly formed tissue (47-48%) and blood vessels (3-4%). No significant differences were found in cellularization and vascularization between uncoated bone scaffolds and n-BG-coated scaffolds. This finding indicates that the decellularized bone itself may exhibit growth-promoting properties induced by the highly interconnected pore microarchitecture and/or proteins left behind on decellularized scaffolds. Even if we did not find proangiogenic effects in n-BG-coated bone scaffolds, a bioactive coating is considered to be beneficial to impart osteoinductive and osteoconductive properties to decellularized bone. n-BG-coated bone grafts have thus high clinical potential for the regeneration of complex tissue defects given their ability for recellularization and neovascularization. © 2012 Wiley Periodicals, Inc.

  19. Cortical and trabecular bone adaptation to incremental load magnitudes using the mouse tibial axial compression loading model.

    Science.gov (United States)

    Weatherholt, Alyssa M; Fuchs, Robyn K; Warden, Stuart J

    2013-01-01

    The mouse tibial axial compression loading model has recently been described to allow simultaneous exploration of cortical and trabecular bone adaptation within the same loaded element. However, the model frequently induces cortical woven bone formation and has produced inconsistent results with regards to trabecular bone adaptation. The aim of this study was to investigate bone adaptation to incremental load magnitudes using the mouse tibial axial compression loading model, with the ultimate goal of revealing a load that simultaneously induced lamellar cortical and trabecular bone adaptation. Adult (16 weeks old) female C57BL/6 mice were randomly divided into three load magnitude groups (5, 7 and 9N), and had their right tibia axially loaded using a continuous 2-Hz haversine waveform for 360 cycles/day, 3 days/week for 4 consecutive weeks. In vivo peripheral quantitative computed tomography was used to longitudinally assess midshaft tibia cortical bone adaptation, while ex vivo micro-computed tomography and histomorphometry were used to assess both midshaft tibia cortical and proximal tibia trabecular bone adaptation. A dose response to loading magnitude was observed within cortical bone, with increasing load magnitude inducing increasing levels of lamellar cortical bone adaptation within the upper two thirds of the tibial diaphysis. Greatest cortical bone adaptation was observed at the midshaft where there was a 42% increase in estimated mechanical properties (polar moment of inertia) in the highest (9N) load group. A dose response to load magnitude was not clearly evident within trabecular bone, with only the highest load (9N) being able to induce measureable adaptation (31% increase in trabecular bone volume fraction at the proximal tibia). The ultimate finding was that a load of 9N (engendering a tensile strain of 1833 με on medial surface of the midshaft tibia) was able to simultaneously induce measurable lamellar cortical and trabecular bone adaptation

  20. Implicaciones funcionales de la señalización purinérgica en la red trabecular

    OpenAIRE

    2005-01-01

    La red trabecular es una estructura situada en la cámara anterior del ojo cuya función es drenar el humor acuoso. Alteraciones en ella pueden producir aumentos de la presión intraocular (IOP) los cuales pueden provocar pérdidas en el campo visual y por lo tanto cegueras parciales o totales (glaucoma).El objetivo de esta tesis doctoral se basa en el estudio de la fisiología de la red trabecular con el fin de tener un mayor conocimiento de sus funciones y así poder entender mejor su papel regul...

  1. Changes in microgaps, micromotion, and trabecular strain from interlocked cement-trabecular bone interfaces in total knee replacements with in vivo service.

    Science.gov (United States)

    Miller, Mark A; Goodheart, Jacklyn R; Khechen, Benjamin; Janssen, Dennis; Mann, Kenneth A

    2016-06-01

    The initial fixation of cemented Total Knee Replacements (TKRs) relies on mechanical interlock between cement and bone, but loss of interlock occurs with in vivo service. In this study, cement-trabeculae gap morphology and micromechanics were measured for lab prepared (representing post-operative state) and postmortem retrieval (with in vivo remodeling) TKRs to determine how changes in fixation affect local micromechanics. Small specimens taken from beneath the tibial tray were loaded with 1 MPa axial compression and the local micromechanics of the trabeculae-cement interface was quantified using digital image correlation. Lab prepared trabeculae that initially interlock with cement had small gaps (ave:14 μm) and limited micromotion (ave:1 μm) which were larger near the cement border. Trabecular resorption was prevalent following in vivo service; interface gaps became larger (ave:40 μm) and micromotion increased (ave:6 μm), particularly near the cement border. Interlocked trabeculae from lab prepared specimens exhibited strains that were 20% of the supporting bone strain, indicating the trabeculae were initially strain shielded. The spatial and temporal progression of gaps, micromotion, and bone strain was complex and much more variable for post-mortem retrievals compared to the lab prepared specimens. From a clinical perspective, attaining more initial interlock results in cement-bone interfaces that are better fixed with less micromotion. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1019-1025, 2016.

  2. Implications of resolution and noise for in vivo micro-MRI of trabecular bone

    Science.gov (United States)

    Li, Charles Q.; Magland, Jeremy F.; Rajapakse, Chamith S.; Guo, X. Edward; Zhang, X. Henry; Vasilic, Branimir; Wehrli, Felix W.

    2008-01-01

    Osteoporotic bone loss is accompanied by impaired structural integrity of the trabecular network, leading to a decrease in the overall mechanical properties of the bone. The development of the “virtual bone biopsy” (VBB), a method combining magnetic resonance microimaging (μMRI) and digital image processing techniques, has previously been shown to quantify topology and scale of human trabecular bone noninvasively. The aim of this work was to determine the extent to which structural parameters derived from images acquired in the limited spatial resolution regime of in vivo imaging are sensitive to resolution and noise and further, whether under these conditions, a small amount of bone loss and its associated structural manifestations can be detected. Toward these goals 3D models of trabecular bone representing multiple anatomic locations were generated on the basis of μCT images of human cadaveric bone cores. These images were binarized and the resulting data arrays representing pure bone (proton density=0) and pure marrow (proton density=255) subjected to simulated MR imaging by Cartesian sampling of k space, yielding, after 3D Fourier reconstruction, voxel sizes currently achievable in vivo. Subsequently, realistic levels of Gaussian noise were superimposed on the complex data and magnitude images were computed. The resulting images were subsequently VBB processed for a range of signal-to-noise ratio (SNR) values and image voxel sizes. For comparison of the predicted behavior to in vivo data, images from a recent patient study were evaluated as well. Systematic changes of the derived structural parameters changing progressively with decreasing SNR were noted, and it is shown that the errors are correctable using simple linear transformations, thereby allowing the data to be normalized. The predicted dependence of the structural parameters on SNR also closely parallel those observed in vivo. Finally, in order to assess the sensitivity of the VBB processing

  3. Influence of object location in different FOVs on trabecular bone microstructure measurements of human mandible: a cone beam CT study

    NARCIS (Netherlands)

    Ibrahim, N.; Parsa, A.; Hassan, B.; van der Stelt, P.; Aartman, I.H.A.; Nambiar, P.

    2014-01-01

    The aim of this study was to assess the influence of different object locations in different fields of view (FOVs) of two cone beam CT (CBCT) systems on trabecular bone microstructure measurements of a human mandible. A block of dry human mandible was scanned at five different locations (centre,

  4. The reliability of cone-beam computed tomography to analyze trabecular and cortical bone structures: an in-vitro study

    OpenAIRE

    Huang, Yan; Dessel, Jeroen Van; Nicolielo, Laura; Van de Casteele, Elke; Slagmolen, Pieter; Jacobs, Reinhilde

    2015-01-01

    Huang Y., Van Dessel J., Nicolielo L., Van de Casteele E., Slagmolen P., Jacobs R., ''The reliability of cone-beam computed tomography to analyze trabecular and cortical bone structures: an in-vitro study'', 24th annual congress of the European Association for Osseointegration - EAO 2015, September 24-26, 2015, Stockholm, Sweden.

  5. Diagnosis of osteoarthritis and prognosis of tibial cartilage loss by quantification of tibia trabecular bone from MRI

    DEFF Research Database (Denmark)

    Marques, Joselene; Genant, Harry K.; Lillholm, Martin

    2013-01-01

    A longitudinal study was used to investigate the quantification of osteoarthritis and prediction of tibial cartilage loss by analysis of the tibia trabecular bone from magnetic resonance images of knees. The Kellgren Lawrence (KL) grades were determined by radiologists and the levels of cartilage...

  6. Influence of object location in different FOVs on trabecular bone microstructure measurements of human mandible: a cone beam CT study

    NARCIS (Netherlands)

    Ibrahim, N.; Parsa, A.; Hassan, B.; van der Stelt, P.; Aartman, I.H.A.; Nambiar, P.

    2014-01-01

    The aim of this study was to assess the influence of different object locations in different fields of view (FOVs) of two cone beam CT (CBCT) systems on trabecular bone microstructure measurements of a human mandible. A block of dry human mandible was scanned at five different locations (centre, lef

  7. Troglitazone treatment increases bone marrow adipose tissue volume but does not affect trabecular bone volume in mice

    DEFF Research Database (Denmark)

    Erikstrup, Lise Tornvig; Mosekilde, Leif; Justesen, J;

    2001-01-01

    proliferator activated receptor-gamma (PPARgamma). Histomorphometric analysis of proximal tibia was performed in order to quantitate the amount of trabecular bone volume per total volume (BV/TV %), adipose tissue volume per total volume (AV/TV %), and hematopoietic marrow volume per total volume (HV...

  8. The classic: The architecture of the trabecular bone (tenth contribution on the mechanics of the human skeletal framework).

    Science.gov (United States)

    von Meyer, Georg Hermann

    2011-11-01

    Hermann von Meyer may rightfully be considered the original proposer of the concept of trabecular architecture following patterns suggesting the directions of principle compressive and tensile stresses in a similarly shaped trabecular structure. Until the mid 19th Century, few had observed trabecular architecture, and when depicted was generally considered to have little regularity. In the 1830s Bourgery, Ward, and Wyman independently described the regularity of trabecular architecture, but according to Koch (1917) the proposed explanations were in error or overly simplified. Karl Culmann, an engineer and the developer of "graphic statics," attended a lecture of von Meyer and made the connection, which was then developed by the latter in this seminal paper. We present the paper in translation here. The original German article entitled "Die Architectur der Spongiosa" was often written in long, cumbersome sentences, with sometimes obscure meanings. We have taken considerable license in translating, rearranging punctuation, and condensing the material into modern terminology and style, while attempting to maintain the flavor of von Meyer's writing. We thank Dr. Per K. Amundson for the original translation; Drs. John Skedros and Richard Brand made additional suggestions. An accompanying biographical sketch of Hermann von Meyer is available at DOI 10.1007/s11999-011-2040-6.

  9. Grizzly bears (Ursus arctos horribilis) and black bears (Ursus americanus) prevent trabecular bone loss during disuse (hibernation).

    Science.gov (United States)

    McGee-Lawrence, Meghan E; Wojda, Samantha J; Barlow, Lindsay N; Drummer, Thomas D; Castillo, Alesha B; Kennedy, Oran; Condon, Keith W; Auger, Janene; Black, Hal L; Nelson, O Lynne; Robbins, Charles T; Donahue, Seth W

    2009-12-01

    Disuse typically causes an imbalance in bone formation and bone resorption, leading to losses of cortical and trabecular bone. In contrast, bears maintain balanced intracortical remodeling and prevent cortical bone loss during disuse (hibernation). Trabecular bone, however, is more detrimentally affected than cortical bone in other animal models of disuse. Here we investigated the effects of hibernation on bone remodeling, architectural properties, and mineral density of grizzly bear (Ursus arctos horribilis) and black bear (Ursus americanus) trabecular bone in several skeletal locations. There were no differences in bone volume fraction or tissue mineral density between hibernating and active bears or between pre- and post-hibernation bears in the ilium, distal femur, or calcaneus. Though indices of cellular activity level (mineral apposition rate, osteoid thickness) decreased, trabecular bone resorption and formation indices remained balanced in hibernating grizzly bears. These data suggest that bears prevent bone loss during disuse by maintaining a balance between bone formation and bone resorption, which consequently preserves bone structure and strength. Further investigation of bone metabolism in hibernating bears may lead to the translation of mechanisms preventing disuse-induced bone loss in bears into novel treatments for osteoporosis.

  10. Differences in Trabecular Bone of Leptin-Deficient ob/ob Mice in Response to Biomechanical Loading

    Directory of Open Access Journals (Sweden)

    Hansjoerg Heep, Christian Wedemeyer, Alexander Wegner, Sebastian Hofmeister, Marius von Knoch

    2008-01-01

    Full Text Available Objective: It is known that bone mineral density (BMD and the strength of bone is predicted by body mass. Fat mass is a significant predictor of bone mineral density which correlates with body weight. This suggests that body fat regulates bone metabolism first by means of hormonal factors and second that the effects of muscle and loading are signaling factors in mechanotransduction. Leptin, a peptide hormone produced predominantly by white fat cells, is one of these hormonal factors. The aim of this study was to investigate and measure by micro-CT the different effects of weight-bearing on trabecular bone formation in mice without the stimulation of leptin. Results: Animals with an ad-libitum-diet (Group A were found to increase body weight significantly at the age of six weeks in comparison with lean mice (Group B. From this point on, the difference increased constantly. At the age of twenty weeks the obese mice were almost twice as heavy as the lean mice. Significant statistical differences are shown between the two groups for body weight and bone mineral density. Examination of trabecular bone (BV/TV, trabecular number (Tb.N., trabecular thickness (Tb.Th. revealed that the only statistically significant difference between the two groups was the Tb.N. for the proximal femur. High weight-bearing insignificantly improved all trabecular bone parameters in the obese mice. Compared with the control-diet Group B, the BV/TV and Tb.N. were slightly higher in the controlled-diet Group A, but not the Tb.Th.. However, correlation was found between Tb.N. and BMD on the one hand and body weight on the other hand. Conclusion: biomechanical loading led to decreased bone mineral density by a decrease in the number of trabeculae. Trabecular thickness was not increased by biomechanical loading in growing mice. Decreased body weight in leptin-deficient mice protects against bone loss. This finding is consistent with the principle of light-weight construction of

  11. 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

    The study of pathological changes of bone is an important task in diagnostic procedures of patients with metabolic bone diseases such as osteoporosis as well as in monitoring the health state of astronauts during long-term space flights. The recent availability of high-resolution three-dimensiona......The study of pathological changes of bone is an important task in diagnostic procedures of patients with metabolic bone diseases such as osteoporosis as well as in monitoring the health state of astronauts during long-term space flights. The recent availability of high-resolution three......-dimensional (3D) imaging of bone challenges the development of data analysis techniques able to assess changes of the 3D microarchitecture of trabecular bone. We introduce an approach based on spatial geometrical properties and define structural measures of complexity for 3D image analysis. These measures...

  12. Modelling of the dielectric properties of trabecular bone samples at microwave frequency

    CERN Document Server

    Irastorza, Ramiro M; Carlevaro, Carlos M; Vericat, Fernando

    2013-01-01

    In this paper the dielectric properties of human trabecular bone are evaluated under physiological condition in the microwave range. Assuming a two components medium, simulation and experimental data are presented and discussed. A special experimental setup is developed in order to deal with inhomogeneous samples. Simulation data are obtained using finite difference time domain from a realistic sample. The bone mineral density of the samples are also measured. The simulation and experimental results of the present study suggest that there is a negative relation between bone volume fraction (BV/TV) and permittivity (conductivity): the higher the BV/TV the lower the permittivity (conductivity). This is in agreement with the recently published in vivo data. Keywords: Bone dielectric properties, Microwave tomography, Finite difference time domain.

  13. Elastic modulus and hardness of cortical and trabecular bovine bone measured by nanoindentation

    Institute of Scientific and Technical Information of China (English)

    WANG X J; CHEN X B; HODGSON P D; WEN C E

    2006-01-01

    The elastic modulus and hardness of several microstructure components of dry bovine vertebrae and tibia have been investigated in the longitude and transverse directions using nanoindentation. The elastic modulus for the osteons and the interstitial lamellae in the longitude direction were found to be (24.7±2.5) GPa and (30.1±2.4) GPa. As it's difficult to distinguish osteons from interstitial lamellae in the transverse direction,the average elastic modulus for cortical bovine bone in the transverse direction was (19.8±1.6) GPa. The elastic modulus for trabecular bone in the longitude and transverse direction were (20±2) GPa and (14.7±1.9) GPa respectively. The hardness also varied among the microstructure components in the range of 0.41-0.89 GPa. Analyses of variance show that the values are significantly different.

  14. A decreased subchondral trabecular bone tissue elastic modulus is associated with pre-arthritic cartilage damage

    DEFF Research Database (Denmark)

    Day, J; Ding, Ming; van der Linden, JC

    2001-01-01

    In osteoarthritis, one postulate is that changes in the mechanical properties of the subchondral bone layer result in cartilage damage. The goal of this study was to examine changes in subchondral trabecular bone properties at the calcified tissue level in the early stages of cartilage damage....... Finite element models were constructed from microCT scans of trabectilar bone from the proximal tibia of donors with mild cartilage damage and from normal donors. In the donors with cartilage damage, macroscopic damage was present only in the medial compartment. The effective tissue elastic moduli were...... determined using a combination of finite element models and mechanical testing. The bone tissue modulus was reduced by 60% in the medial condyle of the cases with cartilage damage compared to the control specimens. Neither the presence of cartilage damage nor the anatomic site (medial vs. lateral) affected...

  15. Trabecular Metal Augments for the Management of Paprosky Type III Defects Without Pelvic Discontinuity.

    Science.gov (United States)

    Grappiolo, Guido; Loppini, Mattia; Longo, Umile Giuseppe; Traverso, Francesco; Mazziotta, Giuseppe; Denaro, Vincenzo

    2015-06-01

    Fifty-five hips undergoing acetabular reconstruction with trabecular metal (TM)-coated cup and TM augments were reviewed at an average follow up of 53.7 months (36-91). Bony defects were Paprosky type IIIA in 42 and type IIIB without pelvic discontinuity in 13 hips. The average HHS increased from 40 (27-52) preoperatively to 90.5 (61-100) postoperatively (P<0.0001). Four (7.3%) of 55 hips underwent acetabular components revision: three cases of loosening (5.4%), and one of recurrent instability (1.8%) were reported. Survival rate at 2 and 5 years was 96.4% and 92.8%. In conclusion, the use of TM-coated cups and augments could be considered an effective management of Paprosky type III defects without pelvic discontinuity providing good clinical and radiographic outcomes in the mid term.

  16. In vivo monitoring of bone architecture and remodeling after implant insertion: The different responses of cortical and trabecular bone.

    Science.gov (United States)

    Li, Zihui; Kuhn, Gisela; von Salis-Soglio, Marcella; Cooke, Stephen J; Schirmer, Michael; Müller, Ralph; Ruffoni, Davide

    2015-12-01

    The mechanical integrity of the bone-implant system is maintained by the process of bone remodeling. Specifically, the interplay between bone resorption and bone formation is of paramount importance to fully understand the net changes in bone structure occurring in the peri-implant bone, which are eventually responsible for the mechanical stability of the bone-implant system. Using time-lapsed in vivo micro-computed tomography combined with new composite material implants, we were able to characterize the spatio-temporal changes of bone architecture and bone remodeling following implantation in living mice. After insertion, implant stability was attained by a quick and substantial thickening of the cortical shell which counteracted the observed loss of trabecular bone, probably due to the disruption of the trabecular network. Within the trabecular compartment, the rate of bone formation close to the implant was transiently higher than far from the implant mainly due to an increased mineral apposition rate which indicated a higher osteoblastic activity. Conversely, in cortical bone, the higher rate of bone formation close to the implant compared to far away was mostly related to the recruitment of new osteoblasts as indicated by a prevailing mineralizing surface. The behavior of bone resorption also showed dissimilarities between trabecular and cortical bone. In the former, the rate of bone resorption was higher in the peri-implant region and remained elevated during the entire monitoring period. In the latter, bone resorption rate had a bigger value away from the implant and decreased with time. Our approach may help to tune the development of smart implants that can attain a better long-term stability by a local and targeted manipulation of the remodeling process within the cortical and the trabecular compartments and, particularly, in bone of poor health.

  17. [Reproducibility and accuracy in the morphometric and mechanical quantification of trabecular bone from 3 Tesla magnetic resonance images].

    Science.gov (United States)

    Alberich-Bayarri, A; Martí-Bonmatí, L; Sanz-Requena, R; Sánchez-González, J; Hervás Briz, V; García-Martí, G; Pérez, M Á

    2014-01-01

    We used an animal model to analyze the reproducibility and accuracy of certain biomarkers of bone image quality in comparison to a gold standard of computed microtomography (μCT). We used magnetic resonance (MR) imaging and μCT to study the metaphyses of 5 sheep tibiae. The MR images (3 Teslas) were acquired with a T1-weighted gradient echo sequence and an isotropic spatial resolution of 180μm. The μCT images were acquired using a scanner with a spatial resolution of 7.5μm isotropic voxels. In the preparation of the images, we applied equalization, interpolation, and thresholding algorithms. In the quantitative analysis, we calculated the percentage of bone volume (BV/TV), the trabecular thickness (Tb.Th), the trabecular separation (Tb.Sp), the trabecular index (Tb.N), the 2D fractal dimension (D(2D)), the 3D fractal dimension (D(3D)), and the elastic module in the three spatial directions (Ex, Ey and Ez). The morphometric and mechanical quantification of trabecular bone by MR was very reproducible, with percentages of variation below 9% for all the parameters. Its accuracy compared to the gold standard (μCT) was high, with errors less than 15% for BV/TV, D(2D), D(3D), and E(app)x, E(app)y and E(app)z. Our experimental results in animals confirm that the parameters of BV/TV, D(2D), D(3D), and E(app)x, E(app)y and E(app)z obtained by MR have excellent reproducibility and accuracy and can be used as imaging biomarkers for the quality of trabecular bone. Copyright © 2013 SERAM. Published by Elsevier Espana. All rights reserved.

  18. Digital tomosynthesis (DTS) for quantitative assessment of trabecular microstructure in human vertebral bone.

    Science.gov (United States)

    Kim, Woong; Oravec, Daniel; Nekkanty, Srikant; Yerramshetty, Janardhan; Sander, Edward A; Divine, George W; Flynn, Michael J; Yeni, Yener N

    2015-01-01

    Digital tomosynthesis (DTS) provides slice images of an object using conventional radiographic methods with high in-plane resolution. The objective of this study was to explore the potential of DTS for describing microstructural, stiffness and stress distribution properties of vertebral cancellous bone. Forty vertebrae (T6, T8, T11, and L3) from 10 cadavers (63-90 years) were scanned using microCT and DTS. Anisotropy (μCT.DA), and the specimen-average and standard deviation of trabecular bone volume fraction (BV/TV), thickness (Tb.Th), number (Tb.N) and separation (Tb.Sp) were obtained using stereology. Apparent modulus (EFEM), and the magnitude (VMExp/σapp) and variability (VMCV) of trabecular stresses were calculated using microCT-based finite element modeling. Mean intercept length, line fraction deviation and fractal parameters were obtained from coronal DTS slices, then correlated with stereological and finite element parameters using linear regression models. Twenty-one DTS parameters (out of 27) correlated to BV/TV, Tb.Th, Tb.N, Tb.Sp and/or μCT.DA (p<0.0001-p<0.05). DTS parameters increased the explained variability in EFEM and VMCV (by 9-11% and 13-19%, respectively; p<0.0001-p<0.04) over that explained by BV/TV. In conclusion, DTS has potential for quantitative assessment of cancellous bone and may be used as a modality complementary to those measuring bone mass for assessing spinal fracture risk. Copyright © 2014 IPEM. Published by Elsevier Ltd. All rights reserved.

  19. Bisphosphonates improve trabecular bone mass and normalize cortical thickness in ovariectomized, osteoblast connexin43 deficient mice.

    Science.gov (United States)

    Watkins, Marcus P; Norris, Jin Yi; Grimston, Susan K; Zhang, Xiaowen; Phipps, Roger J; Ebetino, Frank H; Civitelli, Roberto

    2012-10-01

    The gap junction protein, connexin43 (Cx43) controls both bone formation and osteoclastogenesis via osteoblasts and/or osteocytes. Cx43 has also been proposed to mediate an anti-apoptotic effect of bisphosphonates, potent inhibitors of bone resorption. We studied whether bisphosphonates are effective in protecting mice with a conditional Cx43 gene deletion in osteoblasts and osteocytes (cKO) from the consequences of ovariectomy on bone mass and strength. Ovariectomy resulted in rapid loss of trabecular bone followed by a slight recovery in wild type (WT) mice, and a similar degree of trabecular bone loss, albeit slightly delayed, occurred in cKO mice. Treatment with either risedronate (20 μg/kg) or alendronate (40 μg/kg) prevented ovariectomy-induced bone loss in both genotypes. In basal conditions, bones of cKO mice have larger marrow area, higher endocortical osteoclast number, and lower cortical thickness and strength relative to WT. Ovariectomy increased endocortical osteoclast number in WT but not in cKO mice. Both bisphosphonates prevented these increases in WT mice, and normalized endocortical osteoclast number, cortical thickness and bone strength in cKO mice. Thus, lack of osteoblast/osteocyte Cx43 does not alter bisphosphonate action on bone mass and strength in estrogen deficiency. These results support the notion that one of the main functions of Cx43 in cortical bone is to restrain osteoblast and/or osteocytes from inducing osteoclastogenesis at the endocortical surface. Copyright © 2012 Elsevier Inc. All rights reserved.

  20. Effect of a novel load-bearing trabecular Nitinol scaffold on rabbit radius bone regeneration

    Energy Technology Data Exchange (ETDEWEB)

    Gotman, Irena, E-mail: gotman@technion.ac.il; Gutmanas, Elazar Y., E-mail: gutmanas@technion.ac.il [Department of Materials Science and Engineering, Techion-Israel Institute of Technology, Haifa, 32000 Israel (Israel); National Research Tomsk Polytechnic University, Tomsk, 634050 (Russian Federation); Zaretzky, Asaph [The Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, 31096 Israel (Israel); Psakhie, Sergey G. [National Research Tomsk Polytechnic University, Tomsk, 634050 (Russian Federation); Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation)

    2015-10-27

    The research aim was to evaluate the bone regeneration capability of novel load-bearing NiTi alloy (Nitinol) scaffolds in a critical-size defect (CSD) model. High strength “trabecular Nitinol” scaffolds were prepared by PIRAC (Powder Immersion Reaction Assisted Coating) annealing of the highly porous Ni foam in Ti powder at 900°C. This was followed by PIRAC nitriding to mitigate the release of potentially toxic Ni ions. Scaffolds phase composition and microstructure were characterized by X-ray diffraction and scanning electron microscopy (SEM/EDS), and their mechanical properties were tested in compression. New Zealand white rabbits received bone defect in right radius and were divided in four groups randomly. In the control group, nothing was placed in the defect. In other groups, NiTi scaffolds were implanted in the defect: (i) as produced, (ii) loaded with bone marrow aspirate (BMA), and (iii) biomimetically CaP-coated. The animals were sacrificed after 12 weeks. The forelimbs with scaffolds were resected, fixed, sectioned and examined in SEM. New bone formation inside the scaffold was studied by EDS analysis and by the processing of backscattered electron images. Bone ingrowth into the scaffold was observed in all implant groups, mostly next to the ulna. New bone formation was strongly enhanced by BMA loading and biomimeatic CaP coating, the bone penetrating as much as 1–1.5 mm into the scaffold. The results of this preliminary study demonstrate that the newly developed high strength trabecular Nitinol scaffolds can be successfully used for bone regeneration in critical size defects.

  1. Effect of a novel load-bearing trabecular Nitinol scaffold on rabbit radius bone regeneration

    Science.gov (United States)

    Gotman, Irena; Zaretzky, Asaph; Psakhie, Sergey G.; Gutmanas, Elazar Y.

    2015-10-01

    The research aim was to evaluate the bone regeneration capability of novel load-bearing NiTi alloy (Nitinol) scaffolds in a critical-size defect (CSD) model. High strength "trabecular Nitinol" scaffolds were prepared by PIRAC (Powder Immersion Reaction Assisted Coating) annealing of the highly porous Ni foam in Ti powder at 900°C. This was followed by PIRAC nitriding to mitigate the release of potentially toxic Ni ions. Scaffolds phase composition and microstructure were characterized by X-ray diffraction and scanning electron microscopy (SEM/EDS), and their mechanical properties were tested in compression. New Zealand white rabbits received bone defect in right radius and were divided in four groups randomly. In the control group, nothing was placed in the defect. In other groups, NiTi scaffolds were implanted in the defect: (i) as produced, (ii) loaded with bone marrow aspirate (BMA), and (iii) biomimetically CaP-coated. The animals were sacrificed after 12 weeks. The forelimbs with scaffolds were resected, fixed, sectioned and examined in SEM. New bone formation inside the scaffold was studied by EDS analysis and by the processing of backscattered electron images. Bone ingrowth into the scaffold was observed in all implant groups, mostly next to the ulna. New bone formation was strongly enhanced by BMA loading and biomimeatic CaP coating, the bone penetrating as much as 1-1.5 mm into the scaffold. The results of this preliminary study demonstrate that the newly developed high strength trabecular Nitinol scaffolds can be successfully used for bone regeneration in critical size defects.

  2. Numerical simulation on the adaptation of forms in trabecular bone to mechanical disuse and basic multi-cellular unit activation threshold at menopause

    Institute of Scientific and Technical Information of China (English)

    He Gong; Yubo Fan; Ming Zhang

    2008-01-01

    The objective of this paper is to identify the effects of mechanical disuse and basic multi-cellular unit (BMU) activation threshold on the form of trabecular bone during menopause. A bone adaptation model with mechanical-biological factors at BMU level was integrated with finite element analysis to simulate the changes of trabecular bone structure during menopause. Mechanical disuse and changes in the BMU activation threshold were applied to the model for the period from 4 years before to 4 years after menopause.The changes in bone volume fraction, trabecular thickness and fractal dimension of the trabecular structures were used to quantify the changes of trabecular bone in three different cases associated with mechanical disuse and BMU activation threshold. It was found that the changes in the simulated bone volume fraction were highly correlated and consistent with clinical data, and that the trabecular thickness reduced signi-ficantly during menopause and was highly linearly correlated with the bone volume fraction, and that the change trend of fractal dimension of the simulated trabecular structure was in correspondence with clinical observations. The numerical simulation in this paper may help to better understand the relationship between the bone morphology and the mecha- nical, as well as biological environment; and can provide a quantitative computational model and methodology for the numerical simulation of the bone structural morphological changes caused by the mechanical environment, and/or the biological environment.

  3. Numerical simulation on the adaptation of forms in trabecular bone to mechanical disuse and basic multi-cellular unit activation threshold at menopause

    Science.gov (United States)

    Gong, He; Fan, Yubo; Zhang, Ming

    2008-04-01

    The objective of this paper is to identify the effects of mechanical disuse and basic multi-cellular unit (BMU) activation threshold on the form of trabecular bone during menopause. A bone adaptation model with mechanical- biological factors at BMU level was integrated with finite element analysis to simulate the changes of trabecular bone structure during menopause. Mechanical disuse and changes in the BMU activation threshold were applied to the model for the period from 4 years before to 4 years after menopause. The changes in bone volume fraction, trabecular thickness and fractal dimension of the trabecular structures were used to quantify the changes of trabecular bone in three different cases associated with mechanical disuse and BMU activation threshold. It was found that the changes in the simulated bone volume fraction were highly correlated and consistent with clinical data, and that the trabecular thickness reduced significantly during menopause and was highly linearly correlated with the bone volume fraction, and that the change trend of fractal dimension of the simulated trabecular structure was in correspondence with clinical observations. The numerical simulation in this paper may help to better understand the relationship between the bone morphology and the mechanical, as well as biological environment; and can provide a quantitative computational model and methodology for the numerical simulation of the bone structural morphological changes caused by the mechanical environment, and/or the biological environment.

  4. Microcomputed tomographic analysis of human condyles in unilateral condylar hyperplasia: increased cortical porosity and trabecular bone volume fraction with reduced mineralisation.

    Science.gov (United States)

    Karssemakers, L H E; Nolte, J W; Tuinzing, D B; Langenbach, G E J; Raijmakers, P G; Becking, A G

    2014-12-01

    Unilateral condylar hyperplasia or hyperactivity is a disorder of growth that affects the mandible, and our aim was to visualise the 3-dimensional bony microstructure of resected mandibular condyles of affected patients. We prospectively studied 17 patients with a clinical presentation of progressive mandibular asymmetry and an abnormal single-photon emission computed tomographic (SPECT) scan. All patients were treated by condylectomy to arrest progression. The resected condyles were scanned with micro-CT (18 μm resolution). Rectangular volumes of interest were selected in 4 quadrants (lateromedial and superoinferior) of the trabecular bone of each condyle. Variables of bone architecture (volume fraction, trabecular number, thickness, and separation, degree of mineralisation, and degree of structural anisotrophy) were calculated with routine morphometric software. Eight of the 17 resected condyles showed clear destruction of the subchondral layer of cortical bone. There was a significant superoinferior gradient for all trabecular variables. Mean (SD) bone volume fraction (25.1 (6) %), trabecular number (1.69 (0.26) mm(-1)), trabecular thickness (0.17 (0.03) mm), and degree of mineralisation (695.39 (39.83) mg HA/cm(3)) were higher in the superior region. Trabecular separation (0.6 (0.16) mm) and structural anisotropy (1.84 (0.28)) were higher in the inferior region. The micro-CT analysis showed increased cortical porosity in many of the condyles studied. It also showed a higher bone volume fraction, greater trabecular thickness and trabecular separation, greater trabecular number, and less mineralisation in the condyles of the 17 patients compared with the known architecture of unaffected mandibular condyles.

  5. No Difference Between Trabecular Metal Cones and Femoral Head Allografts in Revision TKA: Minimum 5-year Followup.

    Science.gov (United States)

    Sandiford, Nemandra A; Misur, Peter; Garbuz, Donald S; Greidanus, Nelson V; Masri, Bassam A

    2017-01-01

    Encouraging clinical results have been reported with the use of femoral head structural allografts and, more recently, trabecular metal cones for the management of large structural defects of the femur and tibia during revision total knee arthroplasty (TKA). However, to our knowledge, there are no published studies comparing these two techniques. Compared with bulk allografts, do trabecular metal cones result in (1) better validated outcomes scores; (2) a lower risk of loosening or revision at 5 years; and (3) fewer surgical complications when used for the management of bone loss in revision TKA? Between 2002 and 2008, three surgeons performed 450 TKA revisions, 45 (10%) of which were performed using augmentation of host bone; in those, femoral head allograft was used in 30 (75%) and trabecular metal cones in 15 (25%). From 2002 to 2007, femoral head allografts were used in all patients (28 patients); from 2007 to 2008, trabecular metal augments were used in all patients. There was a period of 1 year (16 knees) in which there was some overlap; during that time, femoral head structural allografts were used in cases in which we were unable to fit the defect or achieve adequate stability with trabecular metal cones. Followup was at a mean of 9 years (range, 5-12 years). No patients were lost to followup. Knee function and quality of life were assessed using the Oxford Knee Score, WOMAC, SF-12, and the UCLA activity score. Radiographs were assessed for signs of loosening. Surgical complications included superficial or deep infections, iatrogenic fractures, symptomatic deep venous thromboses or pulmonary emboli, and blood loss requiring transfusion; these were obtained from our database and from review of patients' charts. The mean Oxford Knee Score in the allograft and trabecular metal cone groups was 91 (SD 10) and 91 (SD 14), respectively (95% confidence interval [CI], 88-94; p = 0.29). Mean WOMAC scores were 94 (SD 10) and 92 (SD 14), respectively (95% CI, 80-105; p

  6. NCBI nr-aa BLAST: CBRC-GACU-03-0016 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-GACU-03-0016 ref|NP_776543.2| myocilin, trabecular meshwork inducible glucocor...ticoid response [Bos taurus] gb|AAI04572.1| Myocilin, trabecular meshwork inducible glucocorticoid response [Bos taurus] NP_776543.2 1e-115 50% ...

  7. NCBI nr-aa BLAST: CBRC-OLAT-17-0016 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-OLAT-17-0016 ref|NP_776543.2| myocilin, trabecular meshwork inducible glucocor...ticoid response [Bos taurus] gb|AAI04572.1| Myocilin, trabecular meshwork inducible glucocorticoid response [Bos taurus] NP_776543.2 1e-99 58% ...

  8. NCBI nr-aa BLAST: CBRC-FRUB-02-0631 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-FRUB-02-0631 sp|Q9XTA3|MYOC_BOVIN Myocilin precursor (Trabecular meshwork-indu...ced glucocorticoid response protein) dbj|BAA82152.1| myocilin/trabecular meshwork inducible glucocorticoid response protein [Bos taurus] Q9XTA3 1e-101 52% ...

  9. NCBI nr-aa BLAST: CBRC-FRUB-02-0631 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-FRUB-02-0631 ref|NP_776543.2| myocilin, trabecular meshwork inducible glucocor...ticoid response [Bos taurus] gb|AAI04572.1| Myocilin, trabecular meshwork inducible glucocorticoid response [Bos taurus] NP_776543.2 1e-102 53% ...

  10. NCBI nr-aa BLAST: CBRC-GACU-03-0016 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-GACU-03-0016 sp|Q9XTA3|MYOC_BOVIN Myocilin precursor (Trabecular meshwork-indu...ced glucocorticoid response protein) dbj|BAA82152.1| myocilin/trabecular meshwork inducible glucocorticoid response protein [Bos taurus] Q9XTA3 1e-114 50% ...

  11. Trabecular micro-bypass Shunt (iStent® : Basic science, clinical, and future

    Directory of Open Access Journals (Sweden)

    E Randy Craven

    2015-01-01

    Full Text Available The trabecular bypass stent offers an alternative to filtration surgery. Patients who may be ideal candidates for considering this procedure are those with prior conjunctival surgery; for example, those who had a 360° peritomy from a scleral buckle might not do well with a trabeculectomy and there is no space for a tube. Highly myopic patients do not tolerate hypotony well, and the iSTB may be an option for some of these patients. I have used the iSTB in patients on anticoagulants who could not stop them, and they needed something beyond medications and laser to lower the IOP in subjects with open-angle glaucoma. Young patients, especially those with one eye, who need rapid visual recovery (for instance to return to work may be good candidates to consider the iSTB as well. Because of the position used for clear corneal cataract surgery, the temporal approach is best for doing these. Therefore, if you are doing cataract surgery on someone who needs a lower IOP, you already are in the correct position to implant the devices. Patients may need some medications after the procedure to lower the IOP to the level desired. The results from Armenia are encouraging, given an IOP of 11.8 mmHg after 2 iSTB stents and taking daily travoprost. These results are difficult to reach even with a trabeculectomy. When selecting your fist patients, avoid those with the congested episcleral veins, look for patients with wide open angles, and if you can see aqueous veins at the slit-lamp it may indicate a viable outflow system. Probably avoid patients with IOPs over 35 mmHg. The micro-invasive trabecular bypass stents offer an alternative surgical intervention for select patients with open-angle glaucoma. Recent studies show that combining these micro-stents with medications can lead to as low of an intraocular pressure (IOP as is achieved by many more invasive incisional surgeries. The technique is quite precise and learning the procedure is similar to clear corneal

  12. Subchondral Bone Plate Changes More Rapidly than Trabecular Bone in Osteoarthritis

    Science.gov (United States)

    Zamli, Zaitunnatakhin; Robson Brown, Kate; Sharif, Mohammed

    2016-01-01

    Osteoarthritis (OA) is the most common joint disorder, characterised by focal loss of cartilage and increased subchondral bone remodelling at early OA stages of the disease. We have investigated the temporal and the spatial relationship between bone remodelling in subchondral bone plate (Sbp) and trabecular bone (Tb) in Dunkin Hartley (DH, develop OA early) and the Bristol Strain 2 (BS2, control which develop OA late) guinea pigs. Right tibias were dissected from six male animals of each strain, at 10, 16, 24 and 30 weeks of age. Micro-computed tomography was used to quantify the growth plate thickness (GpTh), subchondral bone plate thickness (SbpTh) and trabecular bone thickness (TbTh), and bone mineral density (BMD) in both Sbp and Tb. The rate of change was calculated for 10–16 weeks, 16–24 weeks and 24–30 weeks. The rate of changes in Sbp and Tb thickness at the earliest time interval (10–16 weeks) were significantly greater in DH guinea pigs than in the growth-matched control strain (BS2). The magnitude of these differences was greater in the medial side than the lateral side (DH: 22.7 and 14.75 µm/week, BS2: 5.63 and 6.67 µm/week, respectively). Similarly, changes in the BMD at the earliest time interval was greater in the DH strain than the BS2, again more pronounced in the disease prone medial compartment (DH: 0.0698 and 0.0372 g/cm3/week, BS2: 0.00457 and 0.00772 g/cm3/week, respectively). These changes observed preceded microscopic and cellular signs of disease as previously reported. The rapid early changes in SbpTh, TbTh, Sbp BMD and Tb BMD in the disease prone DH guinea pigs compared with the BS2 control strain suggest a link to early OA pathology. This is corroborated by the greater relative changes in subchondral bone in the medial compared with the lateral compartment. PMID:27618009

  13. [Olpadronate prevents cortical and trabecular bone loss induced by supraphysiological dosis of thyroxine in ovariectomized rats].

    Science.gov (United States)

    Zeni, S N; Gómez Acotto, C; Di Gregorio, S

    1998-01-01

    The aim of the present report was to clarify the effect of excess T4 on axial and peripheral bone mineral density (BMD) in estrogen-depleted rats. The protective effect of olpadronate (Olpa) on axial and peripheral bone mass in thyroxine-treated rats was also investigated. Female Sprague-Dawley rats were used: SHAM, OVX + Vh, OVX + Olpa (0.3 mg/kg/week), OVX + T4 (250 micrograms/kg/day) and OVX + T4 + Olpa rats. OVX + Vh group presented a BMD lower than SHAM in the tibia (p < 0.01) but not in femur or lumbar spine; the middle tibia BMD did not change but it was lower at the distal (pns.) and proximal levels (p < 0.003) in OVX + Vh. OVX + T4 rats presented a BMD significantly lower than OVX + Vh rats in total tibia (p < 0.02), femur (p < 0.006) and lumbar spine (p < 0.006). Moreover the BMD was lower in all studied areas of the tibia, but it was statistically significant only at the middle level (p < 0.004). OVX + Olpa rats had a BMD higher than OVX + Vh rats in femur (p < 0.002), lumbar spine (p < 0.0001), total (p < 0.001) and proximal tibia (p < 0.001). Surprisingly, total and proximal tibia BMD values in OVX + Olpa rats presented a BMD significantly higher than OVX + T4 rats in femur (p < 0.001), lumbar spine (p < 0.001), tibia (p < 0.001) and proximal tibia (p < 0.0001). It is important to point out that OVX + T4 + Olpa BMD was significantly higher than in SHAM rats at the lumbar spine, total and proximal tibia (p < 0.01). The present study suggests that although supraphysiological thyroid hormone affected both cortical and trabecular bone, under estrogen-depleted conditions, the cortical bone appears to be more sensitive than the trabecular bone to T4 treatment. We also found that Olpa could prevent the peripheral and axial bone loss induced by thyroid hormone excess.

  14. Trabecular metal acetabular revision system (cup-cage construct to address the massive acetabular defects in revision arthroplasty

    Directory of Open Access Journals (Sweden)

    Rajesh Malhotra

    2012-01-01

    Full Text Available The increasing number of total hip replacements in the younger clique has added to the demand for revision procedures. Revision situations are often encountered with infection, loss of bone stock and bone defects. There are various methods of reconstruction of acetabular defects. The management options of type 3B Paprosky acetabular defects are limited with allograft and conventional cages. Trabecular metal technology has evolved to address these bone defects. Trabecular metal acetabular revision system (TMARS cup-cage construct is a new technique to address massive acetabular defects. We describe a case of failed hip reconstruction done for a Giant cell tumour of proximal femur managed by a two stage procedure, initial debridement and second stage reconstruction of acetabulum with TMARS cup-cage construct and femur with allograft prosthesis composite.

  15. CT evidence for subchondral trabecular injury of the femoral head in transient osteoporosis of the hip: a case report.

    Science.gov (United States)

    Kim, Yong Lae; Nam, Kwang Woo; Yoo, Jeong Joon; Hong, Sung Hwan; Kim, Hee Joong

    2010-01-01

    A 28-yr-old woman presented with both hip pain that started sequentially during the peripartum period. Diagnosis of transient osteoporosis of the hip (TOH) was made based on typical findings of plain radiographs and magnetic resonance images. The subchondral trabeculae of the femoral head were evaluated on serially taken coronal multiplanar reformation computerized tomogram images. At 4 weeks after pain onset, marked decrease in the sclerotic density with irregular discontinuation was observed in the primary compression trabeculae. At 12 weeks, a focal area of irregular thickening of trabeculae was observed. At 20 weeks, sclerotic density of trabeculae recovered markedly and the focal area of irregular trabecular thickening disappeared. At 1 yr, subchondral trabeculae recovered almost completely. The evidence of subchondral trabecular injury was observed in the femoral heads of TOH.

  16. Radiography of the mandible prior to endosseous implant treatment. Localization of the mandibular canal and assessment of trabecular bone

    Energy Technology Data Exchange (ETDEWEB)

    Lindh, C.

    1996-03-01

    Mandibular autopsy specimens were examined with different radiographic techniques in order to evaluate the visibility of the mandibular canal and the measurement accuracy of distances related to the mandibular canal. Hypocycloidal, spiral and computed tomography (CT) were superior to periapical and panoramic radiography in visualizing the mandibular canal. The tomographic techniques were more accurate when measurements of distances related to the mandibular canal were performed. No difference in measurement accuracy was found between the tomographic techniques. Concerning visibility of the mandibular canal, interobserver agreement was lowest for periapical radiography and highest for CT. Intraobserver agreement was moderate or good for all techniques. A high interobserver variation was found for measurability of distances related to the mandibular canal. The trabecular bone tissue in mandibular autopsy specimens was studied concerning different characteristics. A classification system to be used prior to implant treatment, based on the trabecular pattern in periapical radiographs, was proposed. 74 refs.

  17. 3D-DXA: Assessing the Femoral Shape, the Trabecular Macrostructure and the Cortex in 3D from DXA images.

    Science.gov (United States)

    Humbert, Ludovic; Martelli, Yves; Fonolla, Roger; Steghofer, Martin; Di Gregorio, Silvana; Malouf, Jorge; Romera, Jordi; Barquero, Luis Miguel Del Rio

    2017-01-01

    The 3D distribution of the cortical and trabecular bone mass in the proximal femur is a critical component in determining fracture resistance that is not taken into account in clinical routine Dual-energy X-ray Absorptiometry (DXA) examination. In this paper, a statistical shape and appearance model together with a 3D-2D registration approach are used to model the femoral shape and bone density distribution in 3D from an anteroposterior DXA projection. A model-based algorithm is subsequently used to segment the cortex and build a 3D map of the cortical thickness and density. Measurements characterising the geometry and density distribution were computed for various regions of interest in both cortical and trabecular compartments. Models and measurements provided by the "3D-DXA" software algorithm were evaluated using a database of 157 study subjects, by comparing 3D-DXA analyses (using DXA scanners from three manufacturers) with measurements performed by Quantitative Computed Tomography (QCT). The mean point-to-surface distance between 3D-DXA and QCT femoral shapes was 0.93 mm. The mean absolute error between cortical thickness and density estimates measured by 3D-DXA and QCT was 0.33 mm and 72 mg/cm(3). Correlation coefficients (R) between the 3D-DXA and QCT measurements were 0.86, 0.93, and 0.95 for the volumetric bone mineral density at the trabecular, cortical, and integral compartments respectively, and 0.91 for the mean cortical thickness. 3D-DXA provides a detailed analysis of the proximal femur, including a separate assessment of the cortical layer and trabecular macrostructure, which could potentially improve osteoporosis management while maintaining DXA as the standard routine modality.

  18. Influence of bone volume fraction and architecture on computed large-deformation failure mechanisms in human trabecular bone.

    Science.gov (United States)

    Bevill, Grant; Eswaran, Senthil K; Gupta, Atul; Papadopoulos, Panayiotis; Keaveny, Tony M

    2006-12-01

    Large-deformation bending and buckling have long been proposed as failure mechanisms by which the strength of trabecular bone can be affected disproportionately to changes in bone density, and thus may represent an important aspect of bone quality. We sought here to quantify the contribution of large-deformation failure mechanisms on strength, to determine the dependence of these effects on bone volume fraction and architecture, and to confirm that the inclusion of large-deformation effects in high-resolution finite element models improves predictions of strength versus experiment. Micro-CT-based finite element models having uniform hard tissue material properties were created from 54 cores of human trabecular bone taken from four anatomic sites (age = 70+/-11; 24 male, 27 female donors), which were subsequently biomechanically tested to failure. Strength predictions were made from the models first including, then excluding, large-deformation failure mechanisms, both for compressive and tensile load cases. As expected, strength predictions versus experimental data for the large-deformation finite element models were significantly improved (p deformation models in both tension and compression. Below a volume fraction of about 0.20, large-deformation failure mechanisms decreased trabecular strength from 5-80% for compressive loading, while effects were negligible above this volume fraction. Step-wise nonlinear multiple regression revealed that structure model index (SMI) and volume fraction (BV/TV) were significant predictors of these reductions in strength (R2 = 0.83, p deformation failure mechanisms on trabecular bone strength is highly heterogeneous and is not well explained by standard architectural metrics.

  19. 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.

  20. Stochastic multi-scale prediction on the apparent elastic moduli of trabecular bone considering uncertainties of biological apatite (BAp) crystallite orientation and image-based modelling.

    Science.gov (United States)

    Basaruddin, Khairul Salleh; Takano, Naoki; Nakano, Takayoshi

    2015-01-01

    An assessment of the mechanical properties of trabecular bone is important in determining the fracture risk of human bones. Many uncertainty factors contribute to the dispersion of the estimated mechanical properties of trabecular bone. This study was undertaken in order to propose a computational scheme that will be able to predict the effective apparent elastic moduli of trabecular bone considering the uncertainties that are primarily caused by image-based modelling and trabecular stiffness orientation. The effect of image-based modelling which focused on the connectivity was also investigated. A stochastic multi-scale method using a first-order perturbation-based and asymptotic homogenisation theory was applied to formulate the stochastically apparent elastic properties of trabecular bone. The effective apparent elastic modulus was predicted with the introduction of a coefficient factor to represent the variation of bone characteristics due to inter-individual differences. The mean value of the predicted effective apparent Young's modulus in principal axis was found at approximately 460 MPa for respective 15.24% of bone volume fraction, and this is in good agreement with other experimental results. The proposed method may provide a reference for the reliable evaluation of the prediction of the apparent elastic properties of trabecular bone.

  1. Micro-computed tomography assisted distal femur metaphyseal blunt punch compression for determining trabecular bone strength in mice.

    Science.gov (United States)

    Sankar, Uma; Pritchard, Zachary J; Voor, Michael J

    2016-05-03

    Shorter generation time and the power of genetic manipulation make mice an ideal model system to study bone biology as well as bone diseases. However their small size presents a challenge to perform strength measurements, particularly of the weight-bearing cancellous bone in the murine long bones. We recently developed an improved method to measure the axial compressive strength of the cancellous bone in the distal femur metaphysis in mice. Transverse micro-computed tomography image slices that are 7µm thick were used to locate the position where the epiphysis-metaphysis transition occurs. This enabled the removal of the distal femur epiphysis at the exact transition point exposing the full extent of metaphyseal trabecular bone, allowing more accurate and consistent measurement of its strength. When applied to a murine model system consisting of five month old male wild-type (WT) and Ca(2+)/calmodulin dependent protein kinase kinase 2 (CaMKK2) knockout (KO) Camkk2(-/-) mice that possess recorded differences in trabecular bone volume, data collected using this method showed good correlation between bone volume fraction and strength of trabecular bone. In combination with micro-computed tomography and histology, this method will provide a comprehensive and consistent assessment of the microarchitecture and tissue strength of the cancellous bone in murine mouse models.

  2. NMR relaxation times of trabecular bone-reproducibility, relationships to tissue structure and effects of sample freezing

    Energy Technology Data Exchange (ETDEWEB)

    Prantner, Viktoria; Isaksson, Hanna; Nissi, Mikko J; Jurvelin, Jukka S [Department of Physics and Mathematics, University of Eastern Finland, PO Box 1627, 70211 Kuopio (Finland); Naervaeinen, Johanna; Groehn, Olli H J [Department of Neurobiology, A I Virtanen Institute for Molecular Sciences, University of Eastern Finland, PO Box 1627, 70211 Kuopio (Finland); Lammentausta, Eveliina [Department of Diagnostic Radiology, Oulu University Hospital, PO Box 50, 90029 OYS, Oulu (Finland); Avela, Janne, E-mail: hanna.isaksson@uef.f [Department of Biology of Physical Activity, University of Jyvaeskylae, PO Box 35, 40014 Jyvaeskylae (Finland)

    2010-12-07

    Nuclear magnetic resonance (NMR) spectroscopy provides a potential tool for non-invasive evaluation of the trabecular bone structure. The objective of this study was to determine the reproducibility of the NMR relaxation parameters (T{sub 2}, Carr-Purcel-T{sub 2}, T{sub 1}{rho}) for fat and water and relate those to the structural parameters obtained by micro-computed tomography ({mu}CT). Especially, we aimed to evaluate the effect of freezing on the relaxation parameters. For storing bone samples, freezing is the standard procedure during which the biochemical and cellular organization of the bone marrow may be affected. Bovine trabecular bone samples were stored at -20 {sup 0}C for 7 days and measured by NMR spectroscopy before and after freezing. The reproducibility of NMR relaxation parameters, as expressed by the coefficient of variation, ranged from 3.1% to 27.9%. In fresh samples, some correlations between NMR and structural parameters (Tb.N, Tb.Sp) were significant (e.g. the relaxation rate for T{sub 2} of fat versus Tb.Sp: r = -0.716, p < 0.01). Freezing did not significantly change the NMR relaxation times but the correlations between relaxation parameters and the {mu}CT structural parameters were not statistically significant after freezing, suggesting some nonsystematic alterations of the marrow structure. Therefore, the use of frozen bone samples for NMR relaxation studies may provide inferior information about the trabecular bone structure.

  3. Experimental validation of a nonlinear μFE model based on cohesive-frictional plasticity for trabecular bone.

    Science.gov (United States)

    Schwiedrzik, J; Gross, T; Bina, M; Pretterklieber, M; Zysset, P; Pahr, D

    2016-04-01

    Trabecular bone is a porous mineralized tissue playing a major load bearing role in the human body. Prediction of age-related and disease-related fractures and the behavior of bone implant systems needs a thorough understanding of its structure-mechanical property relationships, which can be obtained using microcomputed tomography-based finite element modeling. In this study, a nonlinear model for trabecular bone as a cohesive-frictional material was implemented in a large-scale computational framework and validated by comparison of μFE simulations with experimental tests in uniaxial tension and compression. A good correspondence of stiffness and yield points between simulations and experiments was found for a wide range of bone volume fraction and degree of anisotropy in both tension and compression using a non-calibrated, average set of material parameters. These results demonstrate the ability of the model to capture the effects leading to failure of bone for three anatomical sites and several donors, which may be used to determine the apparent behavior of trabecular bone and its evolution with age, disease, and treatment in the future.

  4. 3D histomorphometric quantification of trabecular bones by computed microtomography using synchrotron radiation.

    Science.gov (United States)

    Nogueira, L P; Braz, D; Barroso, R C; Oliveira, L F; Pinheiro, C J G; Dreossi, D; Tromba, G

    2010-12-01

    Conventional bone histomorphometry is an important method for quantitative evaluation of bone microstructure. X-ray computed microtomography is a non-invasive technique, which can be used to evaluate histomorphometric indices in trabecular bones (BV/TV, BS/BV, Tb.N, Tb.Th, Tb.Sp). In this technique, 3D images are used to quantify the whole sample, differently from the conventional one, in which the quantification is performed in 2D slices and extrapolated for 3D case. In this work, histomorphometric quantification using synchrotron 3D X-ray computed microtomography was performed to quantify the bone structure at different skeletal sites as well as to investigate the effects of bone diseases on quantitative understanding of bone architecture. The images were obtained at Synchrotron Radiation for MEdical Physics (SYRMEP) beamline, at ELETTRA synchrotron radiation facility, Italy. Concerning the obtained results for normal and pathological bones from same skeletal sites and individuals, from our results, a certain declining bone volume fraction was achieved. The results obtained could be used in forming the basis for comparison of the bone microarchitecture and can be a valuable tool for predicting bone fragility.

  5. Ultrasonic non destructive characterization of trabecular bone: estimation of the propagation velocity and attenuation

    Directory of Open Access Journals (Sweden)

    Bennamane A.

    2014-01-01

    Full Text Available The non destructive characterization of porous structures with ultrasonic waves allows determining the propagation velocities and the attenuation for diagnosis of diseased bone (e.g., osteoporosis by establishing correlations between ultrasonic parameters and their mineral density. Two compressional modes have been identified independently in bovine trabecular bone, a fast wave and a slow wave. The principal objective of this paper is to characterize the propagation velocity and ultrasonic attenuation as functions of frequency and porosity of bovine cancellous bone. The porosity of the used samples varies between 40 % and 75 %. A transmission technique is used. This method only requires the measurement of the specimen’s thickness and recording of two pulses: one without and one with the specimen inserted between the transmitting and receiving transducers. From the two pulses, the attenuation can be determined using spectral analysis. The attenuation coefficient increases nonlinearly over the frequency from 200 to 700 kHz. The experimental results show a strong correlation between the bone density, the measured propagation velocity and the attenuation. The measurement of these velocities allows determining the bone elastic parameters. This study confirms the sensitivity of the ultrasonic propagation velocity to the change of bone porosity. The potential of ultrasound in bone tissue characterization seems to provide interesting results and would lead to predict bone pathology and particularly permit better diagnosis of bone fragility.

  6. Production of New Trabecular Bone in Osteopenic Ovariectomized Rats by Prostaglandin E2

    Science.gov (United States)

    Mori, S.; Jee, W. S. S.; Li, X. J.

    1992-01-01

    Serum chemistry and bone morphometry of the proximal tibial metaphysis were performed in 3 month-old double fluorescent-labeled, female Sprague-Dawley rats subjected to bilateral ovariectomy or sham surgery for 4 months prior to treatment with 0, 0.3, 1,3, or 6 mg of prostaglandin E2 (PGE2)/kg/day subcutaneously for 30 days. The 4 month postovariectomized rats possessed an osteopenic proximal tibial metaphysis with 7% trabecular area compared with controls (19%). PGE2 treatment elevated osteocalcin levels and augmented proximal tibial metaphyseal bone area in ovariectomized and sham-operated rats. Osteopenic, ovariectomized rats treated with 6 mg (PGE2)/kg/day for 30 days restored bone area to levels of agematched sham-operated rats. Morphometric analyses showed increased woven and lamellar bone area, fluorescent-labeled perimeter (osteoblastic recruitment), mineral apposition rate (osteoblastic activity), bone formation rate (BFR/BV), and longitudinal bone growth. These dramatic bone changes were all significantly increased at the doseresponse manner. This study showed that in vivo PGE2 is a powerful activator of bone remodeling, it increases both bone resorption and bone formation, and produces an anabolic effect by shifting bone balance to the positive direction. Furthermore, PGE2-induced augmentation of metaphyseal bone area in ovariectomized rats was at least two times greater than in sham-operated rats.

  7. Bone mineral measurements of subchondral and trabecular bone in healthy and osteoporotic rabbits

    Energy Technology Data Exchange (ETDEWEB)

    Castaneda, S [Universidad Autonoma, Rheumatology Department, Hospital de la Princesa, Madrid (Spain); Largo, R.; Marcos, M.E.; Herrero-Beaumont, G. [Universidad Autonoma, Inflammation Research Unit, Rheumatology Department, Fundacion Jimenez Diaz, Madrid (Spain); Calvo, E. [Universidad Autonoma, Inflammation Research Unit, Rheumatology Department, Fundacion Jimenez Diaz, Madrid (Spain); Universidad Autonoma, Department of Orthopaedic Surgery, Fundacion Jimenez Diaz, Madrid (Spain); Rodriguez-Salvanes, F. [Universidad Autonoma, Clinical Epidemiology Unit, Hospital de la Princesa, Madrid (Spain); Diaz-Curiel, M. [Universidad Autonoma, Department of Internal Medicine, Fundacion Jimenez Diaz, Madrid (Spain)

    2006-01-01

    Experimental models of osteoporosis in rabbits are useful to investigate anabolic agents because this animal has a fast bone turnover with predominant remodelling over the modelling processes. For that purpose, it is necessary to characterize the densitometric values of each type of bony tissue. To determine areal bone mass measurement in the spine and in trabecular, cortical and subchondral bone of the knee in healthy and osteoporotic rabbits. Bone mineral content and bone mineral density were measured in lumbar spine, global knee, and subchondral and cortical bone of the knee with dual energy X-ray absorptiometry using a Hologic QDR-1000/W densitometer in 29 skeletally mature female healthy New Zealand rabbits. Ten rabbits underwent triplicate scans for evaluation of the effect of repositioning. Osteoporosis was experimentally induced in 15 rabbits by bilateral ovariectomy and postoperative corticosteroid treatment for 4 weeks. Identical dual energy X-ray absorptiometry (DXA) studies were performed thereafter. Mean values of bone mineral content at the lumbar spine, global knee, subchondral bone and cortical tibial metaphysis were: 1934{+-}217 mg, 878{+-}83 mg, 149{+-}14 mg and 29{+-}7.0 mg, respectively. The mean values of bone mineral density at the same regions were: 298{+-}24 mg/cm{sup 2}, 455{+-}32 mg/cm{sup 2}, 617{+-}60 mg/cm{sup 2} and 678{+-}163 mg/cm{sup 2}, respectively. (orig.)

  8. Initial clinical experience with the trabecular micro-bypass stent in patients with glaucoma.

    Science.gov (United States)

    Spiegel, Detlev; Wetzel, Wolfgang; Haffner, David S; Hill, Richard A

    2007-01-01

    This study was undertaken to evaluate the efficiency of a trabecular micro-bypass stent designed to allow direct aqueous drainage from the anterior chamber into Schlemm's canal in patients with glaucoma. In this prospective case series of 6 patients with open-angle glaucoma, the microstent was inserted ab interno under local anesthesia in an ophthalmic operating room. Patients were seen postoperatively at 1 to 2 d, 1 wk, and 1, 2, 6, and 12 mo. All stents were successfully placed within Schlemm's canal. Mean intraocular pressure (IOP) at preoperative baseline was 20.2+/-6.3 mm Hg (range, 14-31 mm Hg). Mean IOP decreased during the immediate postoperative period to approximately 12 to 13 mm Hg and was stabilized at 14 to 15 mm Hg with reduction of medication throughout 1 y of follow-up. No major complications occurred. According to observations reported in this feasibility study, the microstent was effective in reducing IOP and in decreasing the number of glaucoma medications required to control IOP. Implantation procedures were safe, and stents remained in place throughout the follow-up period. None of the complications traditionally associated with filtering surgery were reported. Further research on this stent in a larger group of patients is needed to assess its role in glaucoma therapy.

  9. Trabecular and cortical microstructure and fragility of the distal radius in women.

    Science.gov (United States)

    Bala, Yohann; Bui, Quang Minh; Wang, Xiao-Fang; Iuliano, Sandra; Wang, Qingju; Ghasem-Zadeh, Ali; Rozental, Tamara D; Bouxsein, Mary L; Zebaze, Roger M D; Seeman, Ego

    2015-04-01

    Fragility fractures commonly involve metaphyses. The distal radius is assembled with a thin cortex formed by fusion (corticalization) of trabeculae arising from the periphery of the growth plate. Centrally positioned trabeculae reinforce the thin cortex and transfer loads from the joint to the proximal thicker cortical bone. We hypothesized that growth- and age-related deficits in trabecular bone disrupt this frugally assembled microarchitecture, producing bone fragility. The microarchitecture of the distal radius was measured using high-resolution peripheral quantitative computed tomography in 135 females with distal radial fractures, including 32 girls (aged 7 to 18 years), 35 premenopausal women (aged 18 to 44 years), and 68 postmenopausal women (aged 50 to 76 years). We also studied 240 fracture-free controls of comparable age and 47 healthy fracture-free premenopausal mother-daughter pairs (aged 30 to 55 and 7 to 20 years, respectively). In fracture-free girls and pre- and postmenopausal women, fewer or thinner trabeculae were associated with a smaller and more porous cortical area (r = 0.25 to 0.71 after age, height, and weight adjustment, all p radius.

  10. A novel composite material specifically developed for ultrasound bone phantoms: cortical, trabecular and skull.

    Science.gov (United States)

    Wydra, A; Maev, R Gr

    2013-11-21

    In the various stages of developing diagnostic and therapeutic equipment, the use of phantoms can play a very important role in improving the process, help in implementation, testing and calibrations. Phantoms are especially useful in developing new applications and training new doctors in medical schools. However, devices that use different physical factors, such as MRI, Ultrasound, CT Scan, etc will require the phantom to be made of different physical properties. In this paper we introduce the properties of recently designed new materials for developing phantoms for ultrasonic human body investigation, which in today's market make up more than 30% in the world of phantoms. We developed a novel composite material which allows fabrication of various kinds of ultrasound bone phantoms to mimic most of the acoustical properties of human bones. In contrast to the ex vivo tissues, the proposed material can maintain the physical and acoustical properties unchanged for long periods of time; moreover, these properties can be custom designed and created to suit specific needs. As a result, we introduce three examples of ultrasound phantoms that we manufactured in our laboratory: cortical, trabecular and skull bone phantoms. The paper also presents the results of a comparison study between the acoustical and physical properties of actual human bones (reported in the referenced literatures) and the phantoms manufactured by us.

  11. A Predictive Model of Vertebral Trabecular Anisotropy From Ex Vivo Micro-CT.

    Science.gov (United States)

    Lekadir, Karim; Hoogendoorn, Corné; Hazrati-Marangalou, Javad; Taylor, Zeike; Noble, Christopher; van Rietbergen, Bert; Frangi, Alejandro F

    2015-08-01

    Spine-related disorders are amongst the most frequently encountered problems in clinical medicine. For several applications such as 1) to improve the assessment of the strength of the spine, as well as 2) to optimize the personalization of spinal interventions, image-based biomechanical modeling of the vertebrae is expected to play an important predictive role. However, this requires the construction of computational models that are subject-specific and comprehensive. In particular, they need to incorporate information about the vertebral anisotropic micro-architecture, which plays a central role in the biomechanical function of the vertebrae. In practice, however, accurate personalization of the vertebral trabeculae has proven to be difficult as its imaging in vivo is currently infeasible. Consequently, this paper presents a statistical approach for accurate prediction of the vertebral fabric tensors based on a training sample of ex vivo micro-CT images. To the best of our knowledge, this is the first predictive model proposed and validated for vertebral datasets. The method combines features selection and partial least squares regression in order to derive optimal latent variables for the prediction of the fabric tensors based on the more easily extracted shape and density information. Detailed validation with 20 ex vivo T12 vertebrae demonstrates the accuracy and consistency of the approach for the personalization of trabecular anisotropy.

  12. Acute hypothalamic suppression significantly affects trabecular bone but not cortical bone following recovery and ovariectomy surgery in a rat model

    Directory of Open Access Journals (Sweden)

    Vanessa R. Yingling

    2016-01-01

    Full Text Available Background. Osteoporosis is “a pediatric disease with geriatric consequences.” Bone morphology and tissue quality co-adapt during ontogeny for sufficient bone stiffness. Altered bone morphology from hypothalamic amenorrhea, a risk factor for low bone mass in women, may affect bone strength later in life. Our purpose was to determine if altered morphology following hypothalamic suppression during development affects cortical bone strength and trabecular bone volume (BV/TV at maturity.Methods. Female rats (25 days old were assigned to a control (C group (n = 45 that received saline injections (.2 cc or an experimental group (GnRH-a (n = 45 that received gonadotropin releasing hormone antagonist injections (.24 mg per dose for 25 days. Fifteen animals from each group were sacrificed immediately after the injection protocol at Day 50 (C, GnRH-a. The remaining animals recovered for 135 days and a subset of each group was sacrificed at Day 185 ((C-R (n = 15 and (G-R (n = 15. The remaining animals had an ovariectomy surgery (OVX at 185 days of age and were sacrificed 40 days later (C-OVX (n = 15 and (G-OVX (n = 15. After sacrifice femurs were mechanically tested and scanned using micro CT. Serum C-terminal telopeptides (CTX and insulin-like growth factor 1 (IGF-1 were measured. Two-way ANOVA (2 groups (GnRH-a and Control X 3 time points (Injection Protocol, Recovery, post-OVX was computed.Results. GnRH-a injections suppressed uterine weights (72% and increased CTX levels by 59%. Bone stiffness was greater in the GnRH-a groups compared to C. Ash content and cortical bone area were similar between groups at all time points. Polar moment of inertia, a measure of bone architecture, was 15% larger in the GnRH-a group and remained larger than C (19% following recovery. Both the polar moment of inertia and cortical area increased linearly with the increases in body weight. Following the injection protocol, trabecular BV/TV was 31% lower in the Gn

  13. Compensatory Role of Inositol 5-Phosphatase INPP5B to OCRL in Primary Cilia Formation in Oculocerebrorenal Syndrome of Lowe.

    Directory of Open Access Journals (Sweden)

    Na Luo

    Full Text Available Inositol phosphatases are important regulators of cell signaling, polarity, and vesicular trafficking. Mutations in OCRL, an inositol polyphosphate 5-phosphatase, result in Oculocerebrorenal syndrome of Lowe, an X-linked recessive disorder that presents with congenital cataracts, glaucoma, renal dysfunction and mental retardation. INPP5B is a paralog of OCRL and shares similar structural domains. The roles of OCRL and INPP5B in the development of cataracts and glaucoma are not understood. Using ocular tissues, this study finds low levels of INPP5B present in human trabecular meshwork but high levels in murine trabecular meshwork. In contrast, OCRL is localized in the trabecular meshwork and Schlemm's canal endothelial cells in both human and murine eyes. In cultured human retinal pigmented epithelial cells, INPP5B was observed in the primary cilia. A functional role for INPP5B is revealed by defects in cilia formation in cells with silenced expression of INPP5B. This is further supported by the defective cilia formation in zebrafish Kupffer's vesicles and in cilia-dependent melanosome transport assays in inpp5b morphants. Taken together, this study indicates that OCRL and INPP5B are differentially expressed in the human and murine eyes, and play compensatory roles in cilia development.

  14. Effect of cannaboid WIN55,212-2 on the expression of cAMP in bovine trabecular meshwork cells in viryo%大麻素WIN55,212-2对体外培养牛眼小梁细胞cAMP表达的影响

    Institute of Scientific and Technical Information of China (English)

    秦维山; 王万辉; 路一凡

    2012-01-01

    目的 通过研究大麻素WIN55,212-2对体外培养牛眼小梁细胞(BTMC)环腺苷酸(cAMP)表达的影响,探讨其增加房水排出而降低眼压的机制.方法 对BTMC进行体外原代培养及传代培养,应用免疫组化的方法鉴定细胞.然后用不同浓度的WIN55,212-2作用于BTMC,放射免疫法检测细胞上清液中cAMP的水平.结果 WIN55,212-2浓度在0.1-20μmol/L范围内,培养液中cAMP水平随浓度增加而显著性升高,若WIN55,212-2浓度继续增高(40-60μmol/L),cAMP水平不再升高.结论 WIN55,212-2可能通过提高BTMC内cAMP水平而起到降低眼压的作用.

  15. In Vivo Precision of Digital Topological Skeletonization Based Individual Trabecula Segmentation (ITS) Analysis of Trabecular Microstructure at the Distal Radius and Tibia by HR-pQCT.

    Science.gov (United States)

    Zhou, Bin; Zhang, Zhendong; Wang, Ji; Yu, Y Eric; Liu, Xiaowei Sherry; Nishiyama, Kyle K; Rubin, Mishaela R; Shane, Elizabeth; Bilezikian, John P; Guo, X Edward

    2016-06-01

    Trabecular plate and rod microstructure plays a dominant role in the apparent mechanical properties of trabecular bone. With high-resolution computed tomography (CT) images, digital topological analysis (DTA) including skeletonization and topological classification was applied to transform the trabecular three-dimensional (3D) network into surface and curve skeletons. Using the DTA-based topological analysis and a new reconstruction/recovery scheme, individual trabecula segmentation (ITS) was developed to segment individual trabecular plates and rods and quantify the trabecular plate- and rod-related morphological parameters. High-resolution peripheral quantitative computed tomography (HR-pQCT) is an emerging in vivo imaging technique to visualize 3D bone microstructure. Based on HR-pQCT images, ITS was applied to various HR-pQCT datasets to examine trabecular plate- and rod-related microstructure and has demonstrated great potential in cross-sectional and longitudinal clinical applications. However, the reproducibility of ITS has not been fully determined. The aim of the current study is to quantify the precision errors of ITS plate-rod microstructural parameters. In addition, we utilized three different frequently used contour techniques to separate trabecular and cortical bone and to evaluate their effect on ITS measurements. Overall, good reproducibility was found for the standard HR-pQCT parameters with precision errors for volumetric BMD and bone size between 0.2%-2.0%, and trabecular bone microstructure between 4.9%-6.7% at the radius and tibia. High reproducibility was also achieved for ITS measurements using all three different contour techniques. For example, using automatic contour technology, low precision errors were found for plate and rod trabecular number (pTb.N, rTb.N, 0.9% and 3.6%), plate and rod trabecular thickness (pTb.Th, rTb.Th, 0.6% and 1.7%), plate trabecular surface (pTb.S, 3.4%), rod trabecular length (rTb.ℓ, 0.8%), and plate

  16. In Vivo Magnetic Resonance Detects Rapid Remodeling Changes in the Topology of the Trabecular Bone Network After Menopause and the Protective Effect of Estradiol

    Science.gov (United States)

    Wehrli, Felix W; Ladinsky, Glenn A; Jones, Catherine; Benito, Maria; Magland, Jeremy; Vasilic, Branimir; Popescu, Andra M; Zemel, Babette; Cucchiara, Andrew J; Wright, Alexander C; Song, Hee K; Saha, Punam K; Peachey, Helen; Snyder, Peter J

    2008-01-01

    Introduction Estrogen depletion after menopause is accompanied by bone loss and architectural deterioration of trabecular bone. The hypothesis underlying this work is that the μMRI-based virtual bone biopsy can capture the temporal changes of scale and topology of the trabecular network and that estrogen supplementation preserves the integrity of the trabecular network. Materials and Methods Subjects studied were early postmenopausal women, 45–55 yr of age (N = 65), of whom 32 were on estrogen (estradiol group), and the remainder were not (control group). Early menopause was defined by amenorrhea for 6–24 mo and elevated serum follicle-stimulating hormone (FSH) concentration. The subjects were evaluated with three imaging modalities at baseline and 12 and 24 mo to determine the temporal changes in trabecular and cortical architecture and density. μMRI of the distal radius and tibia was performed at 137 × 137 × 410-μm3 voxel size. The resulting bone volume fraction maps were Fourier interpolated to a final voxel size of 45.7 × 45.7 × 136.7 μm3, binarized, skeletonized, and subjected to 3D digital topological analysis (DTA). Skeletonization converts trabecular rods to curves and plates to surfaces. Parameters quantifying scale included BV/TV, whereas DTA parameters included the volume densities of curves (C) and surface (S)-type voxels, as well as composite parameters: the surface/curve ratio (S/C), and erosion index (EI, ratio of the sum of parameters expected to increase with osteoclastic resorption divided by the sum of those expected to decrease). For comparison, pQCT of the same peripheral locations was conducted, and trabecular density and cortical structural parameters were measured. Areal BMD of the lumbar vertebrae and hip was also measured. Results Substantial changes in trabecular architecture of the distal tibia, in particular as they relate to topology of the network, were detected after 12 mo in the control group. S/C decreased 5.6% (p < 0

  17. Directional fractal signature methods for trabecular bone texture in hand radiographs: Data from the Osteoarthritis Initiative

    Energy Technology Data Exchange (ETDEWEB)

    Wolski, M., E-mail: marcin.wolski@curtin.edu.au; Podsiadlo, P.; Stachowiak, G. W. [Tribology Laboratory, School of Civil and Mechanical Engineering, Curtin University, Bentley, Western Australia 6102 (Australia)

    2014-08-15

    Purpose: To develop directional fractal signature methods for the analysis of trabecular bone (TB) texture in hand radiographs. Problems associated with the small size of hand bones and the orientation of fingers were addressed. Methods: An augmented variance orientation transform (AVOT) and a quadrant rotating grid (QRG) methods were developed. The methods calculate fractal signatures (FSs) in different directions. Unlike other methods they have the search region adjusted according to the size of bone region of interest (ROI) to be analyzed and they produce FSs defined with respect to any chosen reference direction, i.e., they work for arbitrary orientation of fingers. Five parameters at scales ranging from 2 to 14 pixels (depending on image size and method) were derived from rose plots of Hurst coefficients, i.e., FS in dominating roughness (FS{sub Sta}), vertical (FS{sub V}) and horizontal (FS{sub H}) directions, aspect ratio (StrS), and direction signatures (StdS), respectively. The accuracy in measuring surface roughness and isotropy/anisotropy was evaluated using 3600 isotropic and 800 anisotropic fractal surface images of sizes between 20 × 20 and 64 × 64 pixels. The isotropic surfaces had FDs ranging from 2.1 to 2.9 in steps of 0.1, and the anisotropic surfaces had two dominating directions of 30° and 120°. The methods were used to find differences in hand TB textures between 20 matched pairs of subjects with (cases: approximate Kellgren-Lawrence (KL) grade ≥2) and without (controls: approximate KL grade <2) radiographic hand osteoarthritis (OA). The OA Initiative public database was used and 20 × 20 pixel bone ROIs were selected on 5th distal and middle phalanges. The performance of the AVOT and QRG methods was compared against a variance orientation transform (VOT) method developed earlier [M. Wolski, P. Podsiadlo, and G. W. Stachowiak, “Directional fractal signature analysis of trabecular bone: evaluation of different methods to detect early

  18. Genetic algorithms as a useful tool for trabecular and cortical bone segmentation.

    Science.gov (United States)

    Janc, K; Tarasiuk, J; Bonnet, A S; Lipinski, P

    2013-07-01

    The aim of this study was to find a semi-automatic method of bone segmentation on the basis of computed tomography (CT) scan series in order to recreate corresponding 3D objects. So, it was crucial for the segmentation to be smooth between adjacent scans. The concept of graphics pipeline computing was used, i.e. simple graphics filters such as threshold or gradient were processed in a manner that the output of one filter became the input of the second one resulting in so called pipeline. The input of the entire stream was the CT scan and the output corresponded to the binary mask showing where a given tissue is located in the input image. In this approach the main task consists in finding the suitable sequence, types and parameters of graphics filters building the pipeline. Because of the high number of desired parameters (in our case 96), it was decided to use a slightly modified genetic algorithm. To determine fitness value, the mask obtained from the parameters found through genetic algorithms (GA) was compared with those manually prepared. The numerical value corresponding to such a comparison has been defined by Dice's coefficient. Preparation of reference masks for a few scans among the several hundreds of them was the only action done manually by a human expert. Using this method, very good results both for trabecular and cortical bones were obtained. It has to be emphasized that as no real border exists between these two bone types, the manually prepared reference masks were quite conventional and therefore charged with errors. As GA is a non-deterministic method, the present work also contains a statistical analysis of the relations existing between various GA parameters and fitness function. Finally the best sets of the GA parameters are proposed.

  19. Influence of trabecular bone quality and implantation direction on press-fit mechanics.

    Science.gov (United States)

    Damm, Niklas B; Morlock, Michael M; Bishop, Nicholas E

    2017-02-01

    Achieving primary stability of uncemented press-fit prostheses in patients with poor quality bone can involve axial implantation forces large enough to cause bone fracture. Radial implantation eliminates intraoperative impaction forces and could prevent this damage. Platens of two commercial implant surfaces ("Beaded" and "Flaked") were implanted onto trabecular bone specimens of varying quality in a press-fit simulator. Samples were implanted with varying interference, either axially (shear) or radially (normal). Push-in and pull-out forces were measured to assess stability. Microstructural changes in the bone were determined from μCT analysis. For force-defined implantation analysis, push-in and pull-out forces both increased proportionally with increasing radial force, independent of implantation direction, bone quality or implant surface. For position-defined implantation analysis, pull-out forces were generally found to increase with interference and to be greater for radial than axial implantation direction, and to be lower for poor quality bone. Bone density increased locally at the tested interface due to implantation, in particular for the Beaded surface under axial implantation. If a safe radial stress can be determined for cortical bone in a particular patient, the associated implantation force, and pull-out force which represents primary stability, can be directly derived, regardless of implantation direction, bone quality or implant surface. Radial implantation delivers primary stability that is no worse than that for axial implantation and may eliminate potentially damaging impaction forces. Development of implant designs based on this principal might improve implant fixation. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:224-233, 2017. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

  20. 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.

  1. Trabecular bone score as a skeletal fragility index in acromegaly patients.

    Science.gov (United States)

    Hong, A R; Kim, J H; Kim, S W; Kim, S Y; Shin, C S

    2016-03-01

    Lumbar spine trabecular bone score (TBS) was significantly decreased in active acromegaly patients. TBS may be useful to assess the skeletal fragility in acromegaly in which bone mineral density (BMD) is not sufficient to represent bone strength and explain the high incidence of fragility fractures in acromegaly patients. Although the data on BMD are controversial, patients with acromegaly have an increased risk of fragility fracture. We examined the lumbar spine TBS to explain the skeletal deterioration in acromegaly patients. We included 14 men and 19 women acromegaly patients who underwent dual-energy X-ray absorptiometry at the time of diagnosis from 2000 to 2014 at Seoul National University Hospital. Ninety-nine age-, sex- and body mass index-matched controls were recruited. Biochemical parameters, lumbar spine TBS, and BMD at all sites were measured. Gonadal status was evaluated at diagnosis. Lumbar spine TBS was lower in acromegaly patients than in controls in both genders (1.345 ± 0.121 vs. 1.427 ± 0.087, P = 0.005 in men; 1.356 ± 0.082 vs. 1.431 ± 0.071, P = 0.001 in women). In contrast, BMD at all sites did not differ between the two groups. Hypogonadal acromegaly patients (men, n = 9; women, n = 12) had lower TBS values compared with controls both in men and women (all P acromegaly patients, lumbar spine TBS was lower than in women controls only (P = 0.041). Skeletal microarchitecture was deteriorated in acromegaly patients as assessed by TBS, which seems to be a consequence of growth hormone excess as well as hypogonadism, especially in women.

  2. Characterization of cellular solids in Ti6Al4V for orthopaedic implant applications: Trabecular titanium.

    Science.gov (United States)

    Marin, E; Fusi, S; Pressacco, M; Paussa, L; Fedrizzi, L

    2010-07-01

    EBM (Electron Beam Melting) technology can be used successfully to obtain cellular solids in metallic biomaterials that can greatly increase osseointegration in arthroprothesis and at the same time maintain good mechanical properties. The investigated structures, called Trabecular Titanium, usually cannot be obtained by traditional machining. Two samples: (A) with a smaller single cell area and, (B) with a bigger single cell area, were produced and studied in this project. They have been completely characterized and compared with the results in similar literature pertinent to Ti6Al4V EBM structures. Relative density was evaluated using different methods, the mean diameter of the open porosities was calculated by Scanning Electron Microscope images; the composition was evaluated using Energy-Dispersive X-Ray Spectroscopy; the microstructure (alpha-beta) was investigated using chemical etching and, the mechanical proprieties were investigated using UMTS. The mean porosity values resulted comparable with spongy bone (63% for A and 72% for B). The mean diameter of the single porosity (650 mum for A and 1400 mum for B) resulted compatible with the osseointegration data from the literature, in particular for sample A. The Vickers micro-hardness tests and the chemical etching demonstrated that the structure is fine, uniform and well distributed. The mechanical test proved that sample (A) was more resistant than sample (B), but sample (B) showed an elastic modulus almost equal to the value of spongy bone. The results of this study suggest that the two Ti6Al4V cellular solids can be used in biomedical applications to promote osseointegration demonstrating that they maybe successfully used in prosthetic implants. Additional implant results will be published in the near future. Copyright 2010 Elsevier Ltd. All rights reserved.

  3. Meshwork-carpet type hydrocarbon reservoir transportation system in Junggar Basin%准噶尔盆地网毯式油气成藏输导体系

    Institute of Scientific and Technical Information of China (English)

    刘桠颖; 徐怀民; 姚卫江; 刘楼军

    2011-01-01

    利用输导体地质综合研究方法,以断层、砂体及断—砂组合关系分析为基础,对准噶尔盆地白垩系油气成藏体系进行研究,分析网毯式油气成藏体系输导体的特征及分布.结果表明:按照输导体与毯状仓储层中底砾岩的接触关系,可建立3类9型输导体样式,包括上沟通型、下沟通型、自沟通型、内沟通型断裂输导体,沟通型、未沟通型不整合面输导体,上沟通型、下沟通型、内沟通型砂体连通输导体;不同类型的输导体组合出“Y”型输导模式、“T”型输导模式、“H”型输导模式;输导体在仓储层的“成毯”和“溢散”过程中起到关键作用;复杂的网状输导体系控制了研究区油气藏的形成、分类及分布特征.%Using the the geological comprehensive study method of transportation system, the hydrocarbon accumulation system of Cretaceous in Junggar Basin was studied based on fault, sand body and matching relationship of sand-fault. The characteristics and the spatial distribution of transportation system of meshwork-carpet type hydrocarbon reservoir system were analyzed. The results show that three classes and nine types of conductor department styles are defined according t6 the contact relationship between elements of transportation systems and basal conglomerate of storage layer. It includes upper-connected type, down-connected type, all-connected type and inner-connected type of fault transportation system, connected type and non-connected type of unconformity transportation system as well as upper-connected type, down-connected type and inner-connected type of sand body connected transportation system. Different types of transportation combinations make three transportation models of oil and gas about "Y" type model, "T" type model, and "H" type model. Transportation system plays a key role in the process of making carpet and diffusion in storage layer. Reticular and complex transportation

  4. Ultrastructural Observations of The Anterior Chamber Angle Tissues in Congenital Glaucoma

    Institute of Scientific and Technical Information of China (English)

    1994-01-01

    Eighteen trabeculectomy specimens of congenital glaucoma were examined by light and transimssion electron microscopy. The results showed that the primary anomalies in congenital glaucoma included the developmental defects of trabecular meshwork, excessive collagen fibrils in the trabecular matrix, shifting forward of ciliary muscle fibres and persistent mesenchymal tissues in the anterior-chamber angle. The authors also pointed out the importance of the secondary lesions of the trabecular meshwork in th...

  5. Bone volume fraction and fabric anisotropy are better determinants of trabecular bone stiffness than other morphological variables.

    Science.gov (United States)

    Maquer, Ghislain; Musy, Sarah N; Wandel, Jasmin; Gross, Thomas; Zysset, Philippe K

    2015-06-01

    As our population ages, more individuals suffer from osteoporosis. This disease leads to impaired trabecular architecture and increased fracture risk. It is essential to understand how morphological and mechanical properties of the cancellous bone are related. Morphology-elasticity relationships based on bone volume fraction (BV/TV) and fabric anisotropy explain up to 98% of the variation in elastic properties. Yet, other morphological variables such as individual trabeculae segmentation (ITS) and trabecular bone score (TBS) could improve the stiffness predictions. A total of 743 micro-computed tomography (μCT) reconstructions of cubic trabecular bone samples extracted from femur, radius, vertebrae, and iliac crest were analyzed. Their morphology was assessed via 25 variables and their stiffness tensor (CFE) was computed from six independent load cases using micro finite element (μFE) analyses. Variance inflation factors were calculated to evaluate collinearity between morphological variables and decide upon their inclusion in morphology-elasticity relationships. The statistically admissible morphological variables were included in a multiple linear regression model of the dependent variable CFE. The contribution of each independent variable was evaluated (ANOVA). Our results show that BV/TV is the best determinant of CFE(r(2) adj  = 0.889), especially in combination with fabric anisotropy (r(2) adj  = 0.968). Including the other independent predictors hardly affected the amount of variance explained by the model (r(2) adj  = 0.975). Across all anatomical sites, BV/TV explained 87% of the variance of the bone elastic properties. Fabric anisotropy further described 10% of the bone stiffness, but the improvement in variance explanation by adding other independent factors was marginal (variables do not bring any further contribution. These overall conclusions remain to be confirmed for specific bone diseases and postelastic properties.

  6. Fractal signature and lacunarity in the measurement of the texture of trabecular bone in clinical CT images.

    Science.gov (United States)

    Dougherty, G; Henebry, G M

    2001-07-01

    Fractal analysis is a method of characterizing complex shapes such as the trabecular structure of bone. Numerous algorithms for estimating fractal dimension have been described, but the Fourier power spectrum method is particularly applicable to self-affine fractals, and facilitates corrections for the effects of noise and blurring in an image. We found that it provided accurate estimates of fractal dimension for synthesized fractal images. For natural texture images fractality is limited to a range of scales, and the fractal dimension as a function of spatial frequency presents as a fractal signature. We found that the fractal signature was more successful at discriminating between these textures than either the global fractal dimension or other metrics such as the mean width and root-mean-square width of the spectral density plots. Different natural textures were also readily distinguishable using lacunarity plots, which explicitly characterize the average size and spatial organization of structural sub-units within an image. The fractal signatures of small regions of interest (32x32 pixels), computed in the frequency domain after corrections for imaging system noise and MTF, were able to characterize the texture of vertebral trabecular bone in CT images. Even small differences in texture due to acquisition slice thickness resulted in measurably different fractal signatures. These differences were also readily apparent in lacunarity plots, which indicated that a slice thickness of 1 mm or less is necessary if essential architectural information is not to be lost. Since lacunarity measures gap size and is not predicated on fractality, it may be particularly useful for characterizing the texture of trabecular bone.

  7. Fractal dimension of trabecular bone: comparison of three histomorphometric computed techniques for measuring the architectural two-dimensional complexity.

    Science.gov (United States)

    Chappard, D; Legrand, E; Haettich, B; Chalès, G; Auvinet, B; Eschard, J P; Hamelin, J P; Baslé, M F; Audran, M

    2001-11-01

    Trabecular bone has been reported as having two-dimensional (2-D) fractal characteristics at the histological level, a finding correlated with biomechanical properties. However, several fractal dimensions (D) are known and computational ways to obtain them vary considerably. This study compared three algorithms on the same series of bone biopsies, to obtain the Kolmogorov, Minkowski-Bouligand, and mass-radius fractal dimensions. The relationships with histomorphometric descriptors of the 2-D trabecular architecture were investigated. Bone biopsies were obtained from 148 osteoporotic male patients. Bone volume (BV/TV), trabecular characteristics (Tb.N, Tb.Sp, Tb.Th), strut analysis, star volumes (marrow spaces and trabeculae), inter-connectivity index, and Euler-Poincaré number were computed. The box-counting method was used to obtain the Kolmogorov dimension (D(k)), the dilatation method for the Minkowski-Bouligand dimension (D(MB)), and the sandbox for the mass-radius dimension (D(MR)) and lacunarity (L). Logarithmic relationships were observed between BV/TV and the fractal dimensions. The best correlation was obtained with D(MR) and the lowest with D(MB). Lacunarity was correlated with descriptors of the marrow cavities (ICI, star volume, Tb.Sp). Linear relationships were observed among the three fractal techniques which appeared highly correlated. A cluster analysis of all histomorphometric parameters provided a tree with three groups of descriptors: for trabeculae (Tb.Th, strut); for marrow cavities (Euler, ICI, Tb.Sp, star volume, L); and for the complexity of the network (Tb.N and the three D's). A sole fractal dimension cannot be used instead of the classic 2-D descriptors of architecture; D rather reflects the complexity of branching trabeculae. Computation time is also an important determinant when choosing one of these methods.

  8. Comparison of radiograph-based texture analysis and bone mineral density with three-dimensional microarchitecture of trabecular bone.

    Science.gov (United States)

    Ranjanomennahary, P; Ghalila, S Sevestre; Malouche, D; Marchadier, A; Rachidi, M; Benhamou, Cl; Chappard, C

    2011-01-01

    Hip fracture is a serious health problem and textural methods are being developed to assess bone quality. The authors aimed to perform textural analysis at femur on high-resolution digital radiographs compared to three-dimensional (3D) microarchitecture comparatively to bone mineral density. Sixteen cadaveric femurs were imaged with an x-ray device using a C-MOS sensor. One 17 mm square region of interest (ROI) was selected in the femoral head (FH) and one in the great trochanter (GT). Two-dimensional (2D) textural features from the co-occurrence matrices were extracted. Site-matched measurements of bone mineral density were performed. Inside each ROI, a 16 mm diameter core was extracted. Apparent density (Dapp) and bone volume proportion (BV/TV(Arch)) were measured from a defatted bone core using Archimedes' principle. Microcomputed tomography images of the entire length of the core were obtained (Skyscan 1072) at 19.8 microm of resolution and usual 3D morphometric parameters were computed on the binary volume after calibration from BV/TV(Arch). Then, bone surface/bone volume, trabecular thickness, trabecular separation, and trabecular number were obtained by direct methods without model assumption and the structure model index was calculated. In univariate analysis, the correlation coefficients between 2D textural features and 3D morphological parameters reached 0.83 at the FH and 0.79 at the GT. In multivariate canonical correlation analysis, coefficients of the first component reached 0.95 at the FH and 0.88 at the GT. Digital radiographs, widely available and economically viable, are an alternative method for evaluating bone microarchitectural structure.

  9. Expanding the Description of Spaceflight Effects beyond Bone Mineral Density [BMD]: Trabecular Bone Score [TBS] in ISS Astronauts

    Science.gov (United States)

    Sibonga, J. D.; Spector, E. R.; King, L. J.; Evans, H. J.; Smith, S. A.

    2014-01-01

    Dual-energy x-ray absorptiometry [DXA] is the widely-applied bone densitometry method used to diagnose osteoporosis in a terrestrial population known to be at risk for age-related bone loss. This medical test, which measures areal bone mineral density [aBMD] of clinically-relevant skeletal sites (e.g., hip and spine), helps the clinician to identify which persons, among postmenopausal women and men older than 50 years, are at high risk for low trauma or fragility fractures and might require an intervention. The most recognized osteoporotic fragility fracture is the vertebral compression fracture which can lead to kyphosis or hunched backs typically seen in the elderly. DXA measurement of BMD however is recognized to be insufficient as a sole index for assessing fracture risk. DXA's limitation may be related to its inability to monitor changes in structural parameters, such as trabecular vs. cortical bone volumes, bone geometry or trabecular microarchitecture. Hence, in order to understand risks to human health and performance due to space exposure, NASA needs to expand its measurements of bone to include other contributors to skeletal integrity. To this aim, the Bone and Mineral Lab conducted a pilot study for a novel measurement of bone microarchitecture that can be obtained by retrospective analysis of DXA scans. Trabecular Bone Score (TBS) assesses changes to trabecular microarchitecture by measuring the grey color "texture" information extracted from DXA images of the lumbar spine. An analysis of TBS in 51 ISS astronauts was conducted to assess if TBS could detect 1) an effect of spaceflight and 2) a response to countermeasures independent of DXA BMD. In addition, changes in trunk body lean tissue mass and in trunk body fat tissue mass were also evaluated to explore an association between body composition, as impacted by ARED exercise, and bone microarchitecture. The pilot analysis of 51 astronaut scans of the lumbar spine suggests that, following an ISS

  10. Jump exercise during hindlimb unloading protect against the deterioration of trabecular bone microarchitecture in growing young rats

    OpenAIRE

    Ju, Yong-In; Sone, Teruki; Ohnaru, Kazuhiro; Choi, Hak-Jin; Choi, Kyung-A; Fukunaga, Masao

    2013-01-01

    Three-dimensional femoral trabecular architecture was investigated in tail-suspended young growing rats and the effects of jump exercise during the period of tail-suspension were also examined. Eight-week-old male Wistar rats (n = 24) were randomly assigned to three body weight-matched groups: a tail suspended group (SUS, n = 8); a sedentary control group (CON, n = 8) and rats primed with jump exercise during the period of tail suspension (JUM, n = 8). The jump exercise protocol consisted of ...

  11. Trabecular and Cortical Bone of Growing C3H Mice Is Highly Responsive to the Removal of Weightbearing.

    Directory of Open Access Journals (Sweden)

    Bing Li

    Full Text Available Genetic make-up strongly influences the skeleton's susceptibility to the loss of weight bearing with some inbred mouse strains experiencing great amounts of bone loss while others lose bone at much smaller rates. At young adulthood, female inbred C3H/HeJ (C3H mice are largely resistant to catabolic pressure induced by unloading. Here, we tested whether the depressed responsivity to unloading is inherent to the C3H genetic make-up or whether a younger age facilitates a robust skeletal response to unloading. Nine-week-old, skeletally immature, female C3H mice were subjected to 3wk of hindlimb unloading (HLU, n = 12 or served as normal baseline controls (BC, n = 10 or age-matched controls (AC, n = 12. In all mice, cortical and trabecular architecture of the femur, as well as levels of bone formation and resorption, were assessed with μCT, histomorphometry, and histology. Changes in bone marrow progenitor cell populations were determined with flow cytometry. Following 21d of unloading, HLU mice had 52% less trabecular bone in the distal femur than normal age-matched controls. Reflecting a loss of trabecular tissue compared to baseline controls, trabecular bone formation rates (BFR/BS in HLU mice were 40% lower than in age-matched controls. Surfaces undergoing osteoclastic resorption were not significantly different between groups. In the mid-diaphysis, HLU inhibited cortical bone growth leading to 14% less bone area compared to age-matched controls. Compared to AC, BFR/BS of HLU mice were 53% lower at the endo-cortical surface and 49% lower at the periosteal surface of the mid-diaphysis. The enriched osteoprogenitor cell population (OPC comprised 2% of the bone marrow stem cells in HLU mice, significantly different from 3% OPC in the AC group. These data show that bone tissue in actively growing C3H mice is lost rapidly, or fails to grow, during the removal of functional weight bearing-in contrast to the insignificant response previously

  12. Fractal lacunarity of trabecular bone and magnetic resonance imaging: New perspectives for osteoporotic fracture risk assessment.

    Science.gov (United States)

    Zaia, Annamaria

    2015-03-18

    Osteoporosis represents one major health condition for our growing elderly population. It accounts for severe morbidity and increased mortality in postmenopausal women and it is becoming an emerging health concern even in aging men. Screening of the population at risk for bone degeneration and treatment assessment of osteoporotic patients to prevent bone fragility fractures represent useful tools to improve quality of life in the elderly and to lighten the related socio-economic impact. Bone mineral density (BMD) estimate by means of dual-energy X-ray absorptiometry is normally used in clinical practice for osteoporosis diagnosis. Nevertheless, BMD alone does not represent a good predictor of fracture risk. From a clinical point of view, bone microarchitecture seems to be an intriguing aspect to characterize bone alteration patterns in aging and pathology. The widening into clinical practice of medical imaging techniques and the impressive advances in information technologies together with enhanced capacity of power calculation have promoted proliferation of new methods to assess changes of trabecular bone architecture (TBA) during aging and osteoporosis. Magnetic resonance imaging (MRI) has recently arisen as a useful tool to measure bone structure in vivo. In particular, high-resolution MRI techniques have introduced new perspectives for TBA characterization by non-invasive non-ionizing methods. However, texture analysis methods have not found favor with clinicians as they produce quite a few parameters whose interpretation is difficult. The introduction in biomedical field of paradigms, such as theory of complexity, chaos, and fractals, suggests new approaches and provides innovative tools to develop computerized methods that, by producing a limited number of parameters sensitive to pathology onset and progression, would speed up their application into clinical practice. Complexity of living beings and fractality of several physio-anatomic structures suggest

  13. Development and testing of texture discriminators for the analysis of trabecular bone in proximal femur radiographs

    Energy Technology Data Exchange (ETDEWEB)

    Huber, M. B.; Carballido-Gamio, J.; Fritscher, K.; Schubert, R.; Haenni, M.; Hengg, C.; Majumdar, S.; Link, T. M. [Department of Radiology and Biomedical Imaging, University of California, 400 Parnassus Avenue, San Francisco, California 94143 (United States); University of Health Sciences, Medical Informatics and Technology, 6060 Hall (Austria); AO Development Institute, 7270 Davos Platz (Switzerland); Medical University Innsbruck, 6020 Innsbruck (Austria); Department of Radiology and Biomedical Imaging, University of California, 400 Parnassus Avenue, San Francisco, California 94143 (United States)

    2009-11-15

    }=0.61 (MF and MG features, p<0.01) and were partially independent of BMD. The correlations were dependent on the choice of the ROI and the texture measure. The best predictive multiregression model for failure load R{sub adj}{sup 2}=0.86 (p<0.001) included a set of recently developed texture methods (MF and SIM) but excluded bone mineral density and commonly used texture measures. Conclusions: The results suggest that texture information contained in trabecular bone structure visualized on radiographs may predict whether an implant anchorage can be used and may determine the local bone quality from preoperative radiographs.

  14. Tamoxifen stimulates calcitonin-producing thyroid C-cells and prevents trabecular bone loss in a rat model of androgen deficiency.

    Science.gov (United States)

    Filipović, Branko; Šošić-Jurjević, Branka; Ajdžanović, Vladimir; Živanović, Jasmina; Isenović, Esma; Popovska-Perčinić, Florina; Milošević, Verica

    2015-05-01

    Thyroid C-cells produce calcitonin (CT), a hypocalcemic hormone, that acts as an inhibitor of bone resorption. In this study, we investigated the effects of tamoxifen (TAM) as a selective estrogen receptor modulator on thyroid C-cells, trabecular bone and biochemical markers of bone metabolism in an animal model of androgen deficiency, represented by middle-aged orchidectomized (Orx) rats. Fifteen-month-old male Wistar rats were divided into: Orx and sham-operated (SO) groups. Rats from one Orx group were injected subcutaneously with TAM citrate (Orx + TAM; 0.3 mg kg(-1) b.w.), while the rats from SO and a second Orx group received vehicle alone, once a day for 3 weeks. The peroxidase-antiperoxidase method was applied for localization of CT in C-cells. Thyroid C-cells were morphometrically and ultrastructurally analyzed. An ImageJ image-processing program was used to measure bone histomorphometric parameters. Blood serum samples were analyzed for CT, osteocalcin (OC), calcium (Ca2+ ) and phosphorus (P). Urinary Ca2+ concentrations were measured. TAM treatment significantly increased thyroid C-cell volume (Vc ) and serum CT when compared with vehicle-treated Orx rats. Analysis of trabecular microarchitecture of the tibia showed that administration of TAM significantly increased cancellous bone area, trabecular thickness and trabecular number, whereas trabecular separation was significantly decreased compared with vehicle-treated Orx rats. Serum OC and urinary Ca2+ concentrations were significantly lower in comparison with the control Orx group. These results indicate that in our rat model of androgen deficiency, TAM stimulated calcitonin-producing thyroid C-cells and increased trabecular bone mass. © 2015 Anatomical Society.

  15. Mechanical and material properties of cortical and trabecular bone from cannabinoid receptor-1-null (Cnr1(-/-)) mice.

    Science.gov (United States)

    Khalid, Aysha B; Goodyear, Simon R; Ross, Ruth A; Aspden, Richard M

    2016-10-01

    The endocannabinoid system is known for its regulatory effects on bone metabolism through the cannabinoid receptors, Cnr1 and Cnr2. In this study we analysed the mechanical and material properties of long bones from Cnr1(-/-) mice on a C57BL/6 background. Tibiae and femora from 5- and 12-week-old mice were subjected to three-point bending to measure bending stiffness and yield strength. Elastic modulus, density and mineral content were measured in the diaphysis. Second moment of area (MOA2), inner and outer perimeters of the cortical shaft and trabecular fractional bone volume (BV/TV) were measured using micro-CT. In Cnr1(-/-) males and females at both ages the bending stiffness was reduced due to a smaller MOA2. Bone from Cnr1(-/-) females had a greater modulus than wild-type controls, although no differences were observed in males. BV/TV of 12-week-old Cnr1(-/-) females was greater than controls, although no difference was seen at 5-weeks. On the contrary, Cnr1(-/-) males had the same BV/TV as controls at 12-weeks while they had significantly lower values at 5-weeks. This study shows that deleting Cnr1 decreases the amount of cortical bone in both males and females at 12-weeks, but increases the amount of trabecular bone only in females.

  16. Trabecular-Iris Circumference Volume in Open Angle Eyes Using Swept-Source Fourier Domain Anterior Segment Optical Coherence Tomography

    Directory of Open Access Journals (Sweden)

    Mohammed Rigi

    2014-01-01

    Full Text Available Purpose. To introduce a new anterior segment optical coherence tomography parameter, trabecular-iris circumference volume (TICV, which measures the integrated volume of the peripheral angle, and establish a reference range in normal, open angle eyes. Methods. One eye of each participant with open angles and a normal anterior segment was imaged using 3D mode by the CASIA SS-1000 (Tomey, Nagoya, Japan. Trabecular-iris space area (TISA and TICV at 500 and 750 µm were calculated. Analysis of covariance was performed to examine the effect of age and its interaction with spherical equivalent. Results. The study included 100 participants with a mean age of 50 (±15 years (range 20–79. TICV showed a normal distribution with a mean (±SD value of 4.75 µL (±2.30 for TICV500 and a mean (±SD value of 8.90 µL (±3.88 for TICV750. Overall, TICV showed an age-related reduction (P=0.035. In addition, angle volume increased with increased myopia for all age groups, except for those older than 65 years. Conclusions. This study introduces a new parameter to measure peripheral angle volume, TICV, with age-adjusted normal ranges for open angle eyes. Further investigation is warranted to determine the clinical utility of this new parameter.

  17. Comparison of micro-CT and cone beam CT on the feasibility of assessing trabecular structures in mandibular condyle.

    Science.gov (United States)

    Liang, Xin; Zhang, Zuyan; Gu, Jianping; Wang, Zhihui; Vandenberghe, Bart; Jacobs, Reinhilde; Yang, Jie; Ma, Guowu; Ling, Haibin; Ma, Xuchen

    2017-07-01

    To evaluate the accuracy of CBCT in assessing trabecular structures. Two human mandibles were scanned by micro-CT (Skyscan 1173 high-energy spiral scan micro-CT; Skyscan NV, Kontich, Belgium) and CBCT (3D Accuitomo 170; Morita, Japan). The CBCT images were reconstructed with 0.5 and 1 mm thicknesses. The condylar images were selected for registration. A parallel algorithm for histogram computation was introduced to perform the registration. A mutual information (MI) value was used to evaluate the match between the images obtained from micro-CT and CBCT. In comparison with the micro-CT image for the two samples, the CBCT image with 0.5 mm thickness has a MI value of 0.873 and 0.903 while that with 1.0 mm thickness has a MI value of 0.741 and 0.752. The CBCT images with 0.5 mm thickness were better matched with micro-CT images. CBCT shows comparable accuracy with high-resolution micro-CT in assessing trabecular structures. CBCT can be a feasible tool to evaluate osseous changes of jaw bones.

  18. Evaluation of the fixation of the trabecular metal wedge in patients undergoing revision of total hip arthroplasty

    Directory of Open Access Journals (Sweden)

    Victor Magalhães Callado

    2014-08-01

    Full Text Available Objective:this study aimed to evaluate the fixation of the trabecular metal wedge in patients undergoing revision of total hip arthroplasty.Methods:twenty-three cases with minimum grading of Paprosky II-B that were operated between July 2008 and February 2013 were evaluated. These cases were evaluated based on radiographs before the operation, immediately after the operation and later on after the operation. Loss of fixation was defined as a change in the abduction angle of the component greater than 10° or any mobilization greater than 6 mm.Results:it was found that there was 100% fixation of the acetabula after a mean of 29.5 months. One case underwent removal of the implanted components due to infection.Conclusions:there is still no consensus regarding the best option for reconstructing hips with bone loss. However, revision using a trabecular metal wedge has presented excellent short-and medium-term results. This qualifies it as an important tool for achieving a fixed and stable acetabular component.

  19. Comparison of the Lag Screw Placements for the Treatment of Stable and Unstable Intertrochanteric Femoral Fractures regarding Trabecular Bone Failure.

    Science.gov (United States)

    Celik, Talip; Mutlu, Ibrahim; Ozkan, Arif; Kisioglu, Yasin

    2016-01-01

    Background. In this study, the cut-out risk of Dynamic Hip Screw (DHS) was investigated in nine different positions of the lag screw for two fracture types by using Finite Element Analysis (FEA). Methods. Two types of fractures (31-A1.1 and A2.1 in AO classification) were generated in the femur model obtained from Computerized Tomography images. The DHS model was placed into the fractured femur model in nine different positions. Tip-Apex Distances were measured using SolidWorks. In FEA, the force applied to the femoral head was determined according to the maximum value being observed during walking. Results. The highest volume percentage exceeding the yield strength of trabecular bone was obtained in posterior-inferior region in both fracture types. The best placement region for the lag screw was found in the middle of both fracture types. There are compatible results between Tip-Apex Distances and the cut-out risk except for posterior-superior and superior region of 31-A2.1 fracture type. Conclusion. The position of the lag screw affects the risk of cut-out significantly. Also, Tip-Apex Distance is a good predictor of the cut-out risk. All in all, we can supposedly say that the density distribution of the trabecular bone is a more efficient factor compared to the positions of lag screw in the cut-out risk.

  20. Comparison of the Lag Screw Placements for the Treatment of Stable and Unstable Intertrochanteric Femoral Fractures regarding Trabecular Bone Failure

    Directory of Open Access Journals (Sweden)

    Talip Celik

    2016-01-01

    Full Text Available Background. In this study, the cut-out risk of Dynamic Hip Screw (DHS was investigated in nine different positions of the lag screw for two fracture types by using Finite Element Analysis (FEA. Methods. Two types of fractures (31-A1.1 and A2.1 in AO classification were generated in the femur model obtained from Computerized Tomography images. The DHS model was placed into the fractured femur model in nine different positions. Tip-Apex Distances were measured using SolidWorks. In FEA, the force applied to the femoral head was determined according to the maximum value being observed during walking. Results. The highest volume percentage exceeding the yield strength of trabecular bone was obtained in posterior-inferior region in both fracture types. The best placement region for the lag screw was found in the middle of both fracture types. There are compatible results between Tip-Apex Distances and the cut-out risk except for posterior-superior and superior region of 31-A2.1 fracture type. Conclusion. The position of the lag screw affects the risk of cut-out significantly. Also, Tip-Apex Distance is a good predictor of the cut-out risk. All in all, we can supposedly say that the density distribution of the trabecular bone is a more efficient factor compared to the positions of lag screw in the cut-out risk.

  1. 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.

  2. Protection of trabecular bone in ovariectomized rats by turmeric (Curcuma longa L.) is dependent on extract composition.

    Science.gov (United States)

    Wright, Laura E; Frye, Jennifer B; Timmermann, Barbara N; Funk, Janet L

    2010-09-08

    Extracts prepared from turmeric (Curcuma longa L., [Zingiberaceae]) containing bioactive phenolic curcuminoids were evaluated for bone-protective effects in a hypogonadal rat model of postmenopausal osteoporosis. Three-month female Sprague-Dawley rats were ovariectomized (OVX) and treated with a chemically complex turmeric fraction (41% curcuminoids by weight) or a curcuminoid-enriched turmeric fraction (94% curcuminoids by weight), both dosed at 60 mg/kg 3x per week, or vehicle alone. Effects of two months of treatment on OVX-induced bone loss were followed prospectively by serial assessment of bone mineral density (BMD) of the distal femur using dual-energy X-ray absorptiometry (DXA), while treatment effects on trabecular bone microarchitecture were assessed at two months by microcomputerized tomography (microCT). Chemically complex turmeric did not prevent bone loss, however, the curcuminoid-enriched turmeric prevented up to 50% of OVX-induced loss of trabecular bone and also preserved the number and connectedness of the strut-like trabeculae. These results suggest that turmeric may have bone-protective effects but that extract composition is a critical factor.

  3. Estimation of femoral bone density from trabecular direct wave and cortical guided wave ultrasound velocities measured at the proximal femur in vivo

    DEFF Research Database (Denmark)

    Barkmann, Reinhard; Dencks, Stefanie; Bremer, Alexander

    2008-01-01

    Bone mineral density (BMD) of the proximal femur is a predictor of hip fracture risk. We developed a Quantitative Ultrasound (QUS) scanner for measurements at this site with similar performance (FemUS). In this study we tested if ultrasound velocities of direct waves through trabecular bone...... echoes reflected from the skin of the leg to yield speed-of-sound (SOS) of different wave components. Data were cross-calibrated and pooled (62 women). Bivariate correlations and a multivariate model were calculated for the estimation of femur BMD. BMD correlated both with trabecular and cortical SOS...

  4. The differential diagnostic value of morphological changes of follicular dendritic cell meshwork between benign and malignant lymphoid tissues proliferative lesions%滤泡树突细胞网形态变化在淋巴组织增生性良恶性病变鉴别诊断中的应用

    Institute of Scientific and Technical Information of China (English)

    朱梅刚; 丁向东; 冯晓东; 徐炜

    2012-01-01

    ) meshwork between benign and malignant lymphoid proliferation lesions. Method The morphologic analysis and type of follucular dendritic cell ( FDC ) meshwork was studied by EnVision two-step methods in 60 cases of reactive lymphoid hyperplasia, 5 cases of HV-CD, 3 cases of atypical hyperplasia of T zone, and 78 cases of various lymphomas ( 73 cases of non-Hodgkin lymphoma and 5 cases of Hodgkin lymphoma ). A panel of antibodies used in the benign and malignant lymphoid hyperplasia lesions plus CD21/CD35 were used to label FDC meshwork. Results The reactive hyperplastic lesions showed ball form and regulated meshwork which has intact surface. The HV-CD showed single or multiple ball meshwork or distinct snake-like meshwork. The T zone atypical hyperplasia, early MCL and MZL showed surface invasive meshwork. The diffuse infiltrative MCL, MZL, T zone lymphoma and DLBCL non-GCB showed coloniza-tive meshwork. The DLBCL GCB and diffuse MCL showed burst meshwork. The FL, NLPHL, NLRCHL and NSCHL showed proliferative meshwork. The AITL showed specific extrafollicular around vessel proliferative meshwork. Conclusion All observed results suggest the morphologic changes of FDC meshwork between benign and malignant lymphoid proliferative lesions showed obvious difference. The morphologic changes of FDC meshwork combined with the histopathology, immunohistochemistry and molecular genetic detection may helpful for the differential diagnosis between benign and malignant of lymphoid proliferative lesions.

  5. Bone ingrowth potential of electron beam and selective laser melting produced trabecular-like implant surfaces with and without a biomimetic coating

    NARCIS (Netherlands)

    Biemond, J.E.; Hannink, G.J.; Verdonschot, N.J.; Buma, P.

    2013-01-01

    The bone ingrowth potential of trabecular-like implant surfaces produced by either selective laser melting (SLM) or electron beam melting (EBM), with or without a biomimetic calciumphosphate coating, was examined in goats. For histological analysis and histomorphometry of bone ingrowth depth and bon

  6. Trabecular bone strains around a dental implant and associated micromotions--a micro-CT-based three-dimensional finite element study.

    NARCIS (Netherlands)

    Limbert, G.; Lierde, C. van; Muraru, O.L.; Walboomers, X.F.; Frank, M.; Hansson, S.; Middleton, J.; Jaecques, S.

    2010-01-01

    The first objective of this computational study was to assess the strain magnitude and distribution within the three-dimensional (3D) trabecular bone structure around an osseointegrated dental implant loaded axially. The second objective was to investigate the relative micromotions between the impla

  7. Trabecular orientation in the human femur and tibia and the relationship with lower-limb alignment for patients with osteoarthritis of the knee.

    Science.gov (United States)

    Sampath, Shameem A; Lewis, Sandra; Fosco, Matteo; Tigani, Domenico

    2015-04-13

    Wolff׳s Law suggests that the orientation of trabeculae in human bone changes in response to altered loading patterns. The aim of this study was to investigate trabecular orientation in both the femur and tibia and to compare this with the mechanical axis of the leg. The study involved analysis of radiographs from patients with osteoarthritis of the knee (n=91). For each patient, the trabecular orientation in both the distal femur and proximal tibia was measured from a standard anteroposterior radiograph of the knee and the mechanical axis of the leg was calculated from a long leg view taken while weight bearing. There was a significant correlation between the mechanical axis and the trabecular orientation in each of the regions considered in the femur (r=-0.41, -0.30, 0.52, and 0.23) and tibia (r=-0.27 and 0.31). Multiple regression analysis, with mechanical axis as the dependent variable, produced an R(2) of 0.62. Greater trabecular anisotropy (i.e. greater alignment) was observed in the medial femur and tibia compared to the lateral side (ptibia will reflect the angle of mechanical loading through the knee.

  8. Micro-finite element simulation of trabecular-bone post-yield behaviour--effects of material model, element size and type.

    Science.gov (United States)

    Verhulp, E; Van Rietbergen, B; Muller, R; Huiskes, R

    2008-08-01

    Micro-finite element (micro-FE) analysis became a standard tool for the evaluation of trabecular bone mechanical properties. The accuracy of micro-FE models for linear analyses is well established. However, the accuracy of recently developed nonlinear micro-FE models for simulations of trabecular bone failure is not known. In this study, a trabecular bone specimen was compressed beyond the apparent yield point. The experiment was simulated using different micro-FE meshes with different element sizes and types, and material models based on cortical bone. The results from the simulations were compared with experimental results to study the effects of the different element and material models. It was found that a decrease in element size from 80 to 40 mum had little effect on predicted post-yield behaviour. Element type and material model had significant effects. Nevertheless, none of the established material models for cortical bone were able to predict the typical descent in the load-displacement curve seen during compression of trabecular bone.

  9. Bone ingrowth potential of electron beam and selective laser melting produced trabecular-like implant surfaces with and without a biomimetic coating

    NARCIS (Netherlands)

    Biemond, J.E.; Hannink, G.J.; Verdonschot, N.J.; Buma, P.

    2013-01-01

    The bone ingrowth potential of trabecular-like implant surfaces produced by either selective laser melting (SLM) or electron beam melting (EBM), with or without a biomimetic calciumphosphate coating, was examined in goats. For histological analysis and histomorphometry of bone ingrowth depth and

  10. Effects of architecture, density and connectivity on the properties of trabecular bone: a two-dimensional, Voronoi cell based model study

    Science.gov (United States)

    Ruiz, Osvaldo; Schouwenaars, Rafael; Ramírez, Edgar I.; Jacobo, Víctor H.; Ortiz, Armando

    2011-10-01

    Trabecular bone, rather than being considered as a homogeneous material, must be analysed as a structure of interconnected beam and plate-like elements. The arrangement and morphology of these elements depend on the specific tissue studied as well as on the physiology of the individual. It is therefore impossible to define the mechanical properties trabecular bone in general. To estimate the properties of an individual structure, flexible numerical models must be developed, which allow the calculation of elastic constants and resistance of tissue previously characterised by non-destructive observation. Voxel-based modelling of structures observed by X-ray microtomography is computation intensive. Here, synthetic 2D-microstructures are analysed, constructed as a collection of Voronoi-cells obtained from the observation of plane sections of cancellous bone. The effect of architecture (vertebra and femur), bone density and loss of trabecular connectivity was researched. The study confirms findings of earlier experimental and numerical studies relating to the effect of these parameters; the technique is efficient in terms of experimental effort and numerical analysis. Consequently, the use of synthetic microstructures based on a Voronoi-cell approximation of the real bone architecture may be a promising approach for the prediction of the mechanical properties of trabecular bone.

  11. Identifying Patient-Specific Pathology in Osteoarthritis Development Based on MicroCT Analysis of Subchondral Trabecular Bone.

    Science.gov (United States)

    Steinbeck, Marla J; Eisenhauer, Peter T; Maltenfort, Mitchell G; Parvizi, Javad; Freeman, Theresa A

    2016-01-01

    The goal of this study was to identify alternative mechanisms of osteoarthritis pathology by analyzing subchondral bone. Femoral condyle samples were collected from post-menopausal female patients with knee osteoarthritis undegoing total knee arthroplasty. In the majority of patients, subchondral trabecular bone volume doubled under a region of the medial femoral condyle with full-thickness cartilage deterioration. However, in a subset of patients the bone volume in this region remained constant. This subset also had larger areas of vascular penetration in the calcified cartilage of the lateral condyle concurrent with increased vascular endothelial growth factor expression. Subtyping by subchondral bone characteristics identified a unique population, which lacked the sclerotic bone characteristic of late-stage osteoarthritis. Identification of subtypes within the osteoarthritis population allows investigation of alternate disease pathologies. Copyright © 2016 Elsevier Inc. All rights reserved.

  12. A Minimum 2-Year Follow-up Using Modular Trabecular Metal Tibial Components in Total Knee Arthroplasty

    Directory of Open Access Journals (Sweden)

    Eddy D Zandee van Rilland

    2015-10-01

    Full Text Available INTRODUCTION: Early failure of tibial components remains a concern in total knee arthroplasty (TKA. Loss of fixation with cemented implants continues to be problematic in young, active patients.  We sought to determine outcomes in patients receiving trabecular metal (TM implants in a single-surgeon community hospital setting. METHODS: A retrospective analysis was performed on 167 consecutive primary TKAs performed on 133 patients utilizing a TM tibial implant with a minimum two years follow-up. RESULTS: Failure due to aseptic loosening occurred in 4 of the 167 cases (2.4%. Local and systemic complication rates were low. Length of hospital stay and tourniquet time data were also reported. CONCLUSION: Overall complications were low in our cohort of patients receiving TM implants.  Longer follow-up is necessary to determine if the outcomes we observed are sustained over time.

  13. Age- and direction-related adaptations of lumbar vertebral trabecular bone with respect to apparent stiffness and tissue level stress distribution

    Science.gov (United States)

    Gong, He; Fan, Yubo; Zhang, Ming; Qin, Ling

    2009-02-01

    The objective of this study was to study the age-related adaptation of lumbar vertebral trabecular bone at the apparent level, as well as the tissue level in three orthogonal directions. Ninety trabecular specimens were obtained from six normal L4 vertebral bodies of six male cadavers in two age groups, three aged 62 years and three aged 69 years, and were scanned using a high-resolution micro-computed tomography (micro-CT) system, then converted to micro-finite element models to do micro-finite element analyses. The relationship between apparent stiffness and bone volume fraction, and the tissue level von Mises stress distribution for each trabecular specimen when compressed separately in the longitudinal direction, medial-lateral and anterior-posterior directions (transverse directions) were derived and compared between two age groups. The results showed that at the apparent level, trabecular bones from 69-year group had stiffer bone structure relative to their volume fractions in all three directions, and in both age groups, changes in bone volume fraction could explain more variations in apparent stiffness in the longitudinal direction than the transverse directions; at the tissue level, aging had little effect on the tissue von Mises stress distributions for the compressions in all the three directions. The novelty of the present study was that it provided quantitative assessments on the age and direction-related adaptation of Chinese male lumbar vertebral trabecular bone from two different levels: stiffness at the apparent level and stress distribution at the tissue level. It may help to understand the failure mechanisms and fracture risks of vertebral body associated with aging and direction for the prevention of fracture risks in elder individuals.

  14. Age- and direction-related adaptations of lumbar vertebral trabecular bone with respect to apparent stiffness and tissue level stress distribution

    Institute of Scientific and Technical Information of China (English)

    He Gong; Yubo Fan; Ming Zhang; Ling Qin

    2009-01-01

    The objective of this study was to study the age-related adaptation of lumbar vertebral trabecular bone at the apparent level, as well as the tissue level in three orthog-onal directions. Ninety trabecular specimens were obtained from six normal L4 vertebral bodies of six male cadavers in two age groups, three aged 62 years and three aged 69 years, and were scanned using a high-resolution micro-computed tomography (micro-CT) system, then converted to micro-finite element models to do micro-finite element analyses. The relationship between apparent stiffness and bone volume fraction, and the tissue level von Mises stress distribution for each trabecular specimen when compressed separately in the longitudinal direction, medial-lateral and anterior-posterior directions (transverse directions) were derived and compared between two age groups. The results showed that at the appar-ent level, trabecular bones from 69-year group had stiffer bone structure relative to their volume fractions in all three directions, and in both age groups, changes in bone volume fraction could explain more variations in apparent stiffness in the longitudinal direction than the transverse directions; at the tissue level, aging had little effect on the tissue von Mises stress distributions for the compressions in all the three directions. The novelty of the present study was that it provided quantitative assessments on the age and direction-related adaptation of Chinese male lumbar vertebral trabec-ular bone from two different levels: stiffness at the apparent level and stress distribution at the tissue level. It may help to understand the failure mechanisms and fracture risks of vertebral body associated with aging and direction for the prevention of fracture risks in elder individuals.

  15. In Vivo μMRI-Based Finite Element and Morphological Analyses of Tibial Trabecular Bone in Eugonadal and Hypogonadal Men Before and After Testosterone Treatment

    Science.gov (United States)

    Zhang, X Henry; Liu, X Sherry; Vasilic, Branimir; Wehrli, Felix W; Benito, Maria; Rajapakse, Chamith S; Snyder, Peter J; Guo, X Edward

    2008-01-01

    Osteoporosis is a major public health problem in men. Hypogonadal men have decreased BMD and deteriorated trabecular bone architecture compared with eugonadal men. Testosterone treatment improves their BMD and trabecular structure. We tested the hypothesis that testosterone replacement in hypogonadal men would also improve their bone's mechanical properties. Ten untreated severely hypogonadal and 10 eugonadal men were selected. The hypogonadal men were treated with a testosterone gel for 24 mo to maintain their serum testosterone concentrations within the normal range. Each subject was assessed before and after 6, 12, and 24 mo of testosterone treatment by μMRI of the distal tibia. A subvolume of each μMR image was converted to a microfinite element (μFE) model, and six analyses were performed, representing three compression and three shear tests. The anisotropic stiffness tensor was calculated, from which the orthotropic elastic material constants were derived. Changes in microarchitecture were also quantified using newly developed individual trabeculae segmentation (ITS)-based and standard morphological analyses. The accuracy of these techniques was examined with simulated μMR images. Significant differences in four estimated anisotropic elastic material constants and most morphological parameters were detected between the eugonadal and hypogonadal men. No significant change in estimated elastic moduli and morphological parameters was detected in the eugonadal group over 24 mo. After 24 mo of treatment, significant increases in estimated elastic moduli E22 (9.0%), E33 (5.1%), G23 (7.2%), and G12 (9.4%) of hypogonadal men were detected. These increases were accompanied by significant increases in trabecular plate thickness. These results suggest that 24 mo of testosterone treatment of hypogonadal men improves estimated elastic moduli of tibial trabecular bone by increased trabecular plate thickness. PMID:18410234

  16. Efficient 3D rigid-body registration of micro-MR and micro-CT trabecular bone images

    Science.gov (United States)

    Rajapakse, C. S.; Magland, J.; Wehrli, S. L.; Zhang, X. H.; Liu, X. S.; Guo, X. E.; Wehrli, F. W.

    2008-03-01

    Registration of 3D images acquired from different imaging modalities such as micro-magnetic resonance imaging (µMRI) and micro-computed tomography (µCT) are of interest in a number of medical imaging applications. Most general-purpose multimodality registration algorithms tend to be computationally intensive and do not take advantage of the shape of the imaging volume. Multimodality trabecular bone (TB) images of cylindrical cores, for example, tend to be misaligned along and around the axial direction more than that around other directions. Additionally, TB images acquired by µMRI can differ substantially from those acquired by µCT due to apparent trabecular thickening from magnetic susceptibility boundary effects and non-linear intensity correspondence. However, they share very similar contrast characteristics since the images essentially represent a binary tomographic system. The directional misalignment and the fundamental similarities of the two types of images can be exploited to achieve fast 3D registration. Here we present an intensity cross-correlation based 3D registration algorithm for registering 3D specimen images from cylindrical cores of cadaveric TB acquired by µMRI and µCT in the context of finite-element modeling to assess the bone's mechanical constants. The algorithm achieves the desired registration by first coarsely approximating the three translational and three rotational parameters required to align the µMR images to the µCT scan coordinate frame and fine-tuning the parameters in the neighborhood of the approximate solution. The algorithm described here is suitable for 3D rigid-body image registration applications where through-plane rotations are known to be relatively small. The accuracy of the technique is constrained by the image resolution and in-plane angular increments used.

  17. Machine learning based analytics of micro-MRI trabecular bone microarchitecture and texture in type 1 Gaucher disease.

    Science.gov (United States)

    Sharma, Gulshan B; Robertson, Douglas D; Laney, Dawn A; Gambello, Michael J; Terk, Michael

    2016-06-14

    Type 1 Gaucher disease (GD) is an autosomal recessive lysosomal storage disease, affecting bone metabolism, structure and strength. Current bone assessment methods are not ideal. Semi-quantitative MRI scoring is unreliable, not standardized, and only evaluates bone marrow. DXA BMD is also used but is a limited predictor of bone fragility/fracture risk. Our purpose was to measure trabecular bone microarchitecture, as a biomarker of bone disease severity, in type 1 GD individuals with different GD genotypes and to apply machine learning based analytics to discriminate between GD patients and healthy individuals. Micro-MR imaging of the distal radius was performed on 20 type 1 GD patients and 10 healthy controls (HC). Fifteen stereological and textural measures (STM) were calculated from the MR images. General linear models demonstrated significant differences between GD and HC, and GD genotypes. Stereological measures, main contributors to the first two principal components (PCs), explained ~50% of data variation and were significantly different between males and females. Subsequent PCs textural measures were significantly different between GD patients and HC individuals. Textural measures also significantly differed between GD genotypes, and distinguished between GD patients with normal and pathologic DXA scores. PCA and SVM predictive analyses discriminated between GD and HC with maximum accuracy of 73% and area under ROC curve of 0.79. Trabecular STM differences can be quantified between GD patients and HC, and GD sub-types using micro-MRI and machine learning based analytics. Work is underway to expand this approach to evaluate GD disease burden and treatment efficacy.

  18. Relationship between sample volumes and modulus of human vertebral trabecular bone in micro-finite element analysis.

    Science.gov (United States)

    Wen, Xin-Xin; Xu, Chao; Zong, Chun-Lin; Feng, Ya-Fei; Ma, Xiang-Yu; Wang, Fa-Qi; Yan, Ya-Bo; Lei, Wei

    2016-07-01

    Micro-finite element (μFE) models have been widely used to assess the biomechanical properties of trabecular bone. How to choose a proper sample volume of trabecular bone, which could predict the real bone biomechanical properties and reduce the calculation time, was an interesting problem. Therefore, the purpose of this study was to investigate the relationship between different sample volumes and apparent elastic modulus (E) calculated from μFE model. 5 Human lumbar vertebral bodies (L1-L5) were scanned by micro-CT. Cubic concentric samples of different lengths were constructed as the experimental groups and the largest possible volumes of interest (VOI) were constructed as the control group. A direct voxel-to-element approach was used to generate μFE models and steel layers were added to the superior and inferior surface to mimic axial compression tests. A 1% axial strain was prescribed to the top surface of the model to obtain the E values. ANOVA tests were performed to compare the E values from the different VOIs against that of the control group. Nonlinear function curve fitting was performed to study the relationship between volumes and E values. The larger cubic VOI included more nodes and elements, and more CPU times were needed for calculations. E values showed a descending tendency as the length of cubic VOI decreased. When the volume of VOI was smaller than (7.34mm(3)), E values were significantly different from the control group. The fit function showed that E values approached an asymptotic values with increasing length of VOI. Our study demonstrated that apparent elastic modulus calculated from μFE models were affected by the sample volumes. There was a descending tendency of E values as the length of cubic VOI decreased. Sample volume which was not smaller than (7.34mm(3)) was efficient enough and timesaving for the calculation of E.

  19. 2-(Dimethylaminoethyl Methacrylate/(2-Hydroxyethyl Methacrylate/α-Tricalcium Phosphate Cryogels for Bone Repair, Preparation and Evaluation of the Biological Response of Human Trabecular Bone-Derived Cells and Mesenchymal Stem Cells

    Directory of Open Access Journals (Sweden)

    Tiago Volkmer

    2014-09-01

    Full Text Available The aim of this work is to evaluate the potential of cryogels to be used as scaffolds in tissue engineering. Scaffolds based on the α-tricalcium phosphate reinforced PDMAEMA (Poly(dimethyl aminoethyl methacrylate/PHEMA (poly(hydroxyethyl methacrylate system were prepared and human trabecular bone-derived cells (HTBs and bone marrow derived-mesenchymal stem cells (BM-MSCs cultured on them. Several features, such as porosity, pore shape, molecular weight between crosslinks and mesh size, are studied. The most suitable PDMAEMA/PHEMA ratio for cell proliferation has been assessed and the viability, adhesion, proliferation and expression of osteoblastic biochemical markers are evaluated. The PDMAEMA/PHEMA ratio influences the scaffolds porosity. Values between 53% ± 5.7% for a greater content in PHEMA and 75% ± 5.5% for a greater content in PDMAEMA have been obtained. The polymer ratio also modifies the pore shape. A greater content in PDMAEMA leads also to bigger network mesh size. Each of the compositions were non-cytotoxic, the seeded cells remained viable for both BM-MSCs and HTBs. Thus, and based on the structural analysis, specimens with a greater content in PDMAEMA seem to provide a better structural environment for their use as scaffolds for tissue engineering. The α-tricalcium phosphate incorporation into the composition seems to favor the expression of the osteogenic phenotype.

  20. TBS (Trabecular Bone Score) Expands Understanding of Spaceflight Effects on the Lumbar Spine of Long-Duration Astronauts

    Science.gov (United States)

    Smith, Scott A.; Watts, Nelson; Hans, Didier; LeBlanc, Adrian; Spector, Elisabeth; King, Lisa; Sibonga, Jean

    2014-01-01

    Bone loss due to long-duration spaceflight has been characterized by both DXA and QCT serial scans. It is unclear if these spaceflight-induced changes in bone mineral density (BMD) and structure result in increased fracture incidence. NASA astronauts currently fly 5 to 6-month missions on the International Space Station (ISS) and at least one 12-month mission is planned. While NASA has measured areal BMD (by DXA) and volumetric BMD (by QCT) and has estimated hip strength (by finite element models of QCT data, no method has yet been used to examine bone micro-architecture from lumbar spine (LS). DXA scans are routinely performed pre- and postflight on all ISS astronauts to follow BMD changes associated with spaceflight. Trabecular Bone Score (TBS) is a relatively new method that measures grey-scale-level texture information extracted from LS DXA images and correlates with 3D parameters of bone micro-architecture. We evaluated the ability of LS TBS to discriminate changes in astronauts who have flown on ISS missions and to determine if TBS can provide additional information compared to DXA. Methods: Lumbar Spine (L1-4) DXA scans from 51 astronauts (mean age, 47 +/- 4 yrs) were divided into 3 groups based on the exercise regimens performed onboard the ISS. "Pre-ARED" (exercise using a load-limited resistive exercise device, <300 lb), "ARED" (exercise with a high-load resistive exercise device, up to 600 lb) and "Bisphos+ARED" group (ARED exercise and a 70-mg alendronate tablet once a week before and during flight, starting 17 days before launch). DXA scans were performed and analyzed on a Hologic Discovery W using the same technician for the pre- and post-flight scans. LSC for the LS in our laboratory is 0.025 g/sq. cm. TBS was performed at the Mercy Hospital, Cincinnati, Ohio on a similar Hologic computer. Data were analyzed using a paired, 2-tailed Student's t-test for the difference between pre- and postflight means. Percent change and % change per month are noted

  1. NPY neuron-specific Y2 receptors regulate adipose tissue and trabecular bone but not cortical bone homeostasis in mice.

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    Yan-Chuan Shi

    Full Text Available BACKGROUND: Y2 receptor signalling is known to be important in neuropeptide Y (NPY-mediated effects on energy homeostasis and bone physiology. Y2 receptors are located post-synaptically as well as acting as auto receptors on NPY-expressing neurons, and the different roles of these two populations of Y2 receptors in the regulation of energy homeostasis and body composition are unclear. METHODOLOGY/PRINCIPAL FINDINGS: We thus generated two conditional knockout mouse models, Y2(lox/lox and NPYCre/+;Y2(lox/lox, in which Y2 receptors can be selectively ablated either in the hypothalamus or specifically in hypothalamic NPY-producing neurons of adult mice. Specific deletion of hypothalamic Y2 receptors increases food intake and body weight compared to controls. Importantly, specific ablation of hypothalamic Y2 receptors on NPY-containing neurons results in a significantly greater adiposity in female but not male mice, accompanied by increased hepatic triglyceride levels, decreased expression of liver carnitine palmitoyltransferase (CPT1 and increased expression of muscle phosphorylated acetyl-CoA carboxylase (ACC. While food intake, body weight, femur length, bone mineral content, density and cortical bone volume and thickness are not significantly altered, trabecular bone volume and number were significantly increased by hypothalamic Y2 deletion on NPY-expressing neurons. Interestingly, in situ hybridisation reveals increased NPY and decreased proopiomelanocortin (POMC mRNA expression in the arcuate nucleus of mice with hypothalamus-specific deletion of Y2 receptors in NPY neurons, consistent with a negative feedback mechanism between NPY expression and Y2 receptors on NPY-ergic neurons. CONCLUSIONS/SIGNIFICANCE: Taken together these data demonstrate the anti-obesogenic role of Y2 receptors in the brain, notably on NPY-ergic neurons, possibly via inhibition of NPY neurons and concomitant stimulation of POMC-expressing neurons in the arcuate nucleus of

  2. Trabecular metal patella--is it really doomed to fail in the totally patellar-deficient knee? A case report of patellar reconstruction with a novel technique.

    Science.gov (United States)

    Kumar Nanjayan, Shashi; Wilton, Timothy

    2014-06-01

    Reconstruction of the patella poses real problems for the revision TKR surgeon, particularly when the patella is absent, fractured or profoundly deficient. The trabecular metal patella was introduced in an attempt to address these issues. However the largest series of such cases published to date cast serious doubts on the validity of using Trabecular Metal (TM) in cases where there is no residual patellar bone stock at all. We present a case where the TM Patellar implant has survived satisfactorily for 8 years post reconstruction in a knee with no residual patella bone, resulting in greatly improved symptoms and function. We believe that this success might be related to specific technical details in the reconstruction and we present the technique. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. 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).

  4. Skeletal development of mice lacking bone sialoprotein (BSP--impairment of long bone growth and progressive establishment of high trabecular bone mass.

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    Wafa Bouleftour

    Full Text Available Adult Ibsp-knockout mice (BSP-/- display shorter stature, lower bone turnover and higher trabecular bone mass than wild type, the latter resulting from impaired bone resorption. Unexpectedly, BSP knockout also affects reproductive behavior, as female mice do not construct a proper "nest" for their offsprings. Multiple crossing experiments nonetheless indicated that the shorter stature and lower weight of BSP-/- mice, since birth and throughout life, as well as their shorter femur and tibia bones are independent of the genotype of the mothers, and thus reflect genetic inheritance. In BSP-/- newborns, µCT analysis revealed a delay in membranous primary ossification, with wider cranial sutures, as well as thinner femoral cortical bone and lower tissue mineral density, reflected in lower expression of bone formation markers. However, trabecular bone volume and osteoclast parameters of long bones do not differ between genotypes. Three weeks after birth, osteoclast number and surface drop in the mutants, concomitant with trabecular bone accumulation. The growth plates present a thinner hypertrophic zone in newborns with lower whole bone expression of IGF-1 and higher IHH in 6 days old BSP-/- mice. At 3 weeks the proliferating zone is thinner and the hypertrophic zone thicker in BSP-/- than in BSP+/+ mice of either sex, maybe reflecting a combination of lower chondrocyte proliferation and impaired cartilage resorption. Six days old BSP-/- mice display lower osteoblast marker expression but higher MEPE and higher osteopontin(Opn/Runx2 ratio. Serum Opn is higher in mutants at day 6 and in adults. Thus, lack of BSP alters long bone growth and membranous/cortical primary bone formation and mineralization. Endochondral development is however normal in mutant mice and the accumulation of trabecular bone observed in adults develops progressively in the weeks following birth. Compensatory high Opn may allow normal endochondral development in BSP-/- mice

  5. Skeletal development of mice lacking bone sialoprotein (BSP)--impairment of long bone growth and progressive establishment of high trabecular bone mass.

    Science.gov (United States)

    Bouleftour, Wafa; Boudiffa, Maya; Wade-Gueye, Ndeye Marième; Bouët, Guénaëlle; Cardelli, Marco; Laroche, Norbert; Vanden-Bossche, Arnaud; Thomas, Mireille; Bonnelye, Edith; Aubin, Jane E; Vico, Laurence; Lafage-Proust, Marie Hélène; Malaval, Luc

    2014-01-01

    Adult Ibsp-knockout mice (BSP-/-) display shorter stature, lower bone turnover and higher trabecular bone mass than wild type, the latter resulting from impaired bone resorption. Unexpectedly, BSP knockout also affects reproductive behavior, as female mice do not construct a proper "nest" for their offsprings. Multiple crossing experiments nonetheless indicated that the shorter stature and lower weight of BSP-/- mice, since birth and throughout life, as well as their shorter femur and tibia bones are independent of the genotype of the mothers, and thus reflect genetic inheritance. In BSP-/- newborns, µCT analysis revealed a delay in membranous primary ossification, with wider cranial sutures, as well as thinner femoral cortical bone and lower tissue mineral density, reflected in lower expression of bone formation markers. However, trabecular bone volume and osteoclast parameters of long bones do not differ between genotypes. Three weeks after birth, osteoclast number and surface drop in the mutants, concomitant with trabecular bone accumulation. The growth plates present a thinner hypertrophic zone in newborns with lower whole bone expression of IGF-1 and higher IHH in 6 days old BSP-/- mice. At 3 weeks the proliferating zone is thinner and the hypertrophic zone thicker in BSP-/- than in BSP+/+ mice of either sex, maybe reflecting a combination of lower chondrocyte proliferation and impaired cartilage resorption. Six days old BSP-/- mice display lower osteoblast marker expression but higher MEPE and higher osteopontin(Opn)/Runx2 ratio. Serum Opn is higher in mutants at day 6 and in adults. Thus, lack of BSP alters long bone growth and membranous/cortical primary bone formation and mineralization. Endochondral development is however normal in mutant mice and the accumulation of trabecular bone observed in adults develops progressively in the weeks following birth. Compensatory high Opn may allow normal endochondral development in BSP-/- mice, while impairing

  6. 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

  7. Pregnant ewes exposed to multiple endocrine disrupting pollutants through sewage sludge-fertilized pasture show an anti-estrogenic effect in their trabecular bone

    Energy Technology Data Exchange (ETDEWEB)

    Lind, P. Monica, E-mail: Monica.Lind@medsci.uu.se [Department of Medical Sciences, Occupational and Environmental Medicine, Uppsala University, Ullerakersvaegen 40, 751 85 Uppsala (Sweden); Oberg, Denise [Department of Environmental Toxicology, Uppsala University, Uppsala (Sweden); Larsson, Sune [Department of Orthopaedics, Uppsala University, Uppsala (Sweden); Kyle, Carol E. [Macaulay Land Use Research Institute, Craigiebuckler, Aberdeen AB15 8QH (United Kingdom); Orberg, Jan [Department of Environmental Toxicology, Uppsala University, Uppsala (Sweden); Rhind, Stewart M. [Macaulay Land Use Research Institute, Craigiebuckler, Aberdeen AB15 8QH (United Kingdom)

    2010-05-01

    Pregnant ewes were maintained on pastures fertilized, twice yearly, with either sewage sludge (2.25 tonnes dry matter/ha; Treated; T) or inorganic fertilizer containing equivalent amounts of nitrogen (Control; C), to determine effects on maternal and fetal bone structures, density and mechanical properties of exposure to environmental concentrations of multiple endocrine disrupting compounds (EDCs) and heavy metal pollutants. The ewes were maintained on the respective pastures from the age of about 8 months until they were 4-6 years of age and they were slaughtered at 110 d gestation. Metaphyseal parts of adult ewe femurs exhibited a significantly reduced mean, total cross sectional area (CSA, - 4%; p < 0.05), lower trabecular bone mineral content (BMC, mg/mm; - 18%; p < 0.05), trabecular bone mineral density (BMD, mg/cm{sup 3}, - 8.0%; p < 0.05) and trabecular CSA, mm{sup 2}, - 11.1%; p < 0.05) in T compared with C animals. Femurs of T ewes were stronger than those of C ewes but this may reflect greater body weights. At the mid-diaphyseal part of the fetal bones, there was a reduction in endosteal circumference (- 6.7%, p < 0.05) and marrow cavity area (- 13.8%, p < 0.05) in the female T fetuses compared with female C fetuses. In the male fetuses the mid-diaphyseal part total bone mineral content was higher (+ 3.0%, p < 0.05) in T than in C animals. No treatment difference in biomechanical bending was detected in the fetuses. It is concluded that ewes grazing pasture fertilized with sewage sludge exhibited an anti-estrogenic effect on their trabecular bone in the form of reduced mineral content and density, despite increased body weight. It is suggested that human exposure to low levels of multiple EDCs may have implications for bone structure and human health.

  8. Chitosan nanofiber scaffold improves bone healing via stimulating trabecular bone production due to upregulation of the Runx2/osteocalcin/alkaline phosphatase signaling pathway

    Science.gov (United States)

    Ho, Ming-Hua; Yao, Chih-Jung; Liao, Mei-Hsiu; Lin, Pei-I; Liu, Shing-Hwa; Chen, Ruei-Ming

    2015-01-01

    Osteoblasts play critical roles in bone formation. Our previous study showed that chitosan nanofibers can stimulate osteoblast proliferation and maturation. This translational study used an animal model of bone defects to evaluate the effects of chitosan nanofiber scaffolds on bone healing and the possible mechanisms. In this study, we produced uniform chitosan nanofibers with fiber diameters of approximately 200 nm. A bone defect was surgically created in the proximal femurs of male C57LB/6 mice, and then the left femur was implanted with chitosan nanofiber scaffolds for 21 days and compared with the right femur, which served as a control. Histological analyses revealed that implantation of chitosan nanofiber scaffolds did not lead to hepatotoxicity or nephrotoxicity. Instead, imaging analyses by X-ray transmission and microcomputed tomography showed that implantation of chitosan nanofiber scaffolds improved bone healing compared with the control group. In parallel, microcomputed tomography and bone histomorphometric assays further demonstrated augmentation of the production of new trabecular bone in the chitosan nanofiber-treated group. Furthermore, implantation of chitosan nanofiber scaffolds led to a significant increase in the trabecular bone thickness but a reduction in the trabecular parameter factor. As to the mechanisms, analysis by confocal microscopy showed that implantation of chitosan nanofiber scaffolds increased levels of Runt-related transcription factor 2 (Runx2), a key transcription factor that regulates osteogenesis, in the bone defect sites. Successively, amounts of alkaline phosphatase and osteocalcin, two typical biomarkers that can simulate bone maturation, were augmented following implantation of chitosan nanofiber scaffolds. Taken together, this translational study showed a beneficial effect of chitosan nanofiber scaffolds on bone healing through stimulating trabecular bone production due to upregulation of Runx2-mediated alkaline

  9. Three-dimensional micro-level computational study of Wolff's law via trabecular bone remodeling in the human proximal femur using design space topology optimization.

    Science.gov (United States)

    Boyle, Christopher; Kim, Il Yong

    2011-03-15

    The law of bone remodeling, commonly referred to as Wolff's Law, asserts that the internal trabecular bone adapts to external loadings, reorienting with the principal stress trajectories to maximize mechanical efficiency creating a naturally optimum structure. The goal of the current study was to utilize an advanced structural optimization algorithm, called design space optimization (DSO), to perform a micro-level three-dimensional finite element bone remodeling simulation on the human proximal femur and analyse the results to determine the validity of Wolff's hypothesis. DSO optimizes the layout of material by iteratively distributing it into the areas of highest loading, while simultaneously changing the design domain to increase computational efficiency. The result is a "fully stressed" structure with minimized compliance and increased stiffness. The large-scale computational simulation utilized a 175 μm mesh resolution and the routine daily loading activities of walking and stair climbing. The resulting anisotropic trabecular architecture was compared to both Wolff's trajectory hypothesis and natural femur samples from literature using a variety of visualization techniques, including radiography and computed tomography (CT). The results qualitatively revealed several anisotropic trabecular regions, that were comparable to the natural human femurs. Quantitatively, the various regional bone volume fractions from the computational results were consistent with quantitative CT analyses. The global strain energy proceeded to become more uniform during optimization; implying increased mechanical efficiency was achieved. The realistic simulated trabecular geometry suggests that the DSO method can accurately predict bone adaptation due to mechanical loading and that the proximal femur is an optimum structure as the Wolff hypothesized.

  10. Cortical and trabecular bone at the radius and tibia in male and female adolescents with Down syndrome: a peripheral quantitative computed tomography (pQCT) study.

    Science.gov (United States)

    González-Agüero, A; Vicente-Rodríguez, G; Gómez-Cabello, A; Casajús, J A

    2013-03-01

    We aimed to describe the structure and strength of the tibia and radius of adolescents with Down syndrome. We observed that despite higher levels of volumetric bone mineral density in determined skeletal sites, they are at higher risk of developing osteoporotic fractures in the future due to their lower bone strength indexes. The aims of the study were to describe the cortical and trabecular volumetric bone mineral density (vBMD), bone mineral content (BMC), area, and bone strength in adolescents with Down syndrome (DS) and to compare them with adolescents without disabilities. Thirty adolescents (11 girls) with DS and 28 without disabilities (10 girls) participated in the study. Peripheral quantitative computed tomography measurements were taken at proximal and distal sites of the tibia and radius. Values of total, trabecular, and cortical BMC; vBMD; and area were obtained of each scan. Cortical thickness and endosteal and periosteal circumferences were also measured, and different bone strength indexes were calculated. Student's t tests were applied between groups. The DS group showed greater vBMD at distal radius, BMC at proximal radius, and total and cortical vBMD at proximal tibia. The non-DS group showed higher total and trabecular area at the distal radius and total, cortical, and trabecular BMC and area at distal tibia. Higher values of periosteal and endosteal circumference and bone strength were also found in non-DS group. From these results, it can be believed that even with higher vBMD in determined skeletal sites, adolescents with DS are at higher risk of suffering bone fractures due to an increased fragility by lower resistance to load bending or torsion.

  11. Application of the Minkowski functionals in 3D to high-resolution MR images of trabecular bone: prediction of the biomechanical strength by nonlinear topological measures

    Science.gov (United States)

    Boehm, Holger F.; Link, Thomas M.; Monetti, Roberto A.; Mueller, Dirk; Rummeny, Ernst J.; Newitt, David; Majumdar, Sharmila; Raeth, Christoph W.

    2004-05-01

    Multi-dimensional convex objects can be characterized with respect to shape, structure, and the connectivity of their components using a set of morphological descriptors known as the Minkowski functionals. In a 3D Euclidian space, these correspond to volume, surface area, mean integral curvature, and the Euler-Poincaré characteristic. We introduce the Minkowski functionals to medical image processing for the morphological analysis of trabecular bone tissue. In the context of osteoporosis-a metabolic disorder leading to a weakening of bone due to deterioration of micro-architecture-the structure of bone increasingly gains attention in the quantification of bone quality. The trabecular architecture of healthy cancellous bone consists of a complex 3D system of inter-connected mineralised elements whereas in osteoporosis the micro-structure is dominated by gaps and disconnections. At present, the standard parameter for diagnosis and assessment of fracture risk in osteoporosis is the bone mineral density (BMD) - a bulk measure of mineralisation irrespective of structural texture characteristics. With the development of modern imaging modalities (high resolution MRI, micro-CT) with spatial resolutions allowing to depict individual trabeculae bone micro-architecture has successfully been analysed using linear, 2- dimensional structural measures adopted from standard histo-morphometry. The preliminary results of our study demonstrate that due to the complex - i.e. the non-linear - network of trabecular bone structures non-linear measures in 3D are superior to linear ones in predicting mechanical properties of trabecular bone from structural information extracted from high resolution MR image data.

  12. Histomorphometric Parameters of the Growth Plate and Trabecular Bone in Wild-Type and Trefoil Factor Family 3 (Tff3)-Deficient Mice Analyzed by Free and Open-Source Image Processing Software.

    Science.gov (United States)

    Bijelić, Nikola; Belovari, Tatjana; Stolnik, Dunja; Lovrić, Ivana; Baus Lončar, Mirela

    2017-08-01

    Trefoil factor family 3 (Tff3) peptide is present during intrauterine endochondral ossification in mice, and its deficiency affects cancellous bone quality in secondary ossification centers of mouse tibiae. The aim of this study was to quantitatively analyze parameters describing the growth plate and primary ossification centers in tibiae of 1-month-old wild-type and Tff3 knock-out mice (n=5 per genotype) by using free and open-source software. Digital photographs of the growth plates and trabecular bone were processed by open-source computer programs GIMP and FIJI. Histomorphometric parameters were calculated using measurements made with FIJI. Tff3 knock-out mice had significantly smaller trabecular number and significantly larger trabecular separation. Trabecular bone volume, trabecular bone surface, and trabecular thickness showed no significant difference between the two groups. Although such histomorphological differences were found in the cancellous bone structure, no significant differences were found in the epiphyseal plate histomorphology. Tff3 peptide probably has an effect on the formation and quality of the cancellous bone in the primary ossification centers, but not through disrupting the epiphyseal plate morphology. This work emphasizes the benefits of using free and open-source programs for morphological studies in life sciences.

  13. A comparison of the texture of computed tomography and projection radiography images of vertebral trabecular bone using fractal signature and lacunarity.

    Science.gov (United States)

    Dougherty, G

    2001-06-01

    The structural integrity of trabecular bone is an important factor characterizing the biomechanical strength of the vertebra, and is determined by the connectivity of the bone network and the trabeculation pattern. These can be assessed using texture measures such as the fractal signature and lacunarity from a high resolution projection radiograph. Using central sections of lumbar vertebrae we compared the results obtained from high-resolution transverse projection images with those obtained from spatially registered low-resolution images from a conventional clinical CT scanner to determine whether clinical CT data can provide useful structural information. Provided the power spectra of the CT images are corrected for image system blurring, the resulting fractal signature is similar for both modalities. Although the CT images are blurred relative to the projection images, with a consequent reduction in lacunarity, the estimated trabecular separation obtained from the lacunarity plots is similar for both modalities. This suggests that these texture measures contain essential information on trabecular microarchitecture, which is present even in low resolution CT images. Such quantitative texture measurements from CT or MRI images are potentially useful in monitoring bone strength and predicting future fracture risk.

  14. Micro-scale finite element modeling of ultrasound propagation in aluminum trabecular bone-mimicking phantoms: A comparison between numerical simulation and experimental results.

    Science.gov (United States)

    Vafaeian, B; Le, L H; Tran, T N H T; El-Rich, M; El-Bialy, T; Adeeb, S

    2016-05-01

    The present study investigated the accuracy of micro-scale finite element modeling for simulating broadband ultrasound propagation in water-saturated trabecular bone-mimicking phantoms. To this end, five commercially manufactured aluminum foam samples as trabecular bone-mimicking phantoms were utilized for ultrasonic immersion through-transmission experiments. Based on micro-computed tomography images of the same physical samples, three-dimensional high-resolution computational samples were generated to be implemented in the micro-scale finite element models. The finite element models employed the standard Galerkin finite element method (FEM) in time domain to simulate the ultrasonic experiments. The numerical simulations did not include energy dissipative mechanisms of ultrasonic attenuation; however, they expectedly simulated reflection, refraction, scattering, and wave mode conversion. The accuracy of the finite element simulations were evaluated by comparing the simulated ultrasonic attenuation and velocity with the experimental data. The maximum and the average relative errors between the experimental and simulated attenuation coefficients in the frequency range of 0.6-1.4 MHz were 17% and 6% respectively. Moreover, the simulations closely predicted the time-of-flight based velocities and the phase velocities of ultrasound with maximum relative errors of 20 m/s and 11 m/s respectively. The results of this study strongly suggest that micro-scale finite element modeling can effectively simulate broadband ultrasound propagation in water-saturated trabecular bone-mimicking structures.

  15. Assessment of bone mineral density by DXA and the trabecular microarchitecture of the calcaneum by texture analysis in pre- and postmenopausal women in the evaluation of osteoporosis

    Directory of Open Access Journals (Sweden)

    Karunanithi R

    2007-01-01

    Full Text Available The in vivo evaluation of trabecular bone structure could be useful in the diagnosis of osteoporosis for the characterization of therapeutic response and understanding the role of parameters other than bone mineral density (BMD in defining skeletal status. This study was made to evaluate changes taking place in the trabecular architecture of bone with age and menopausal status in women. The findings are compared with the femoral neck bone as well as the trochantar bone mineral density determined by dual energy X-ray absorptiometry (DXA, which is a standard reference test for evaluation of osteoporosis. Seventy females were recruited for the study, 25 pre-menopausal (mean age ± SD: 39.4 ± 3.8 and 45 postmenopausal (mean age ± SD: 57.9 ± 7.9 women. The right femoral neck bone mineral density was measured for them by dual energy X-ray absorptiometry (DXA. For the same individuals, lateral view radiographs of the right calcaneum were taken as well. The radiographs were digitized and the region of interest (ROI of 256 x 256 pixels was selected, the run-length matrix was computed for calculating seven parameters [Table 1] and the two-dimensional fast Fourier transform of the image was calculated. Using the FFT, the power spectral density (PSD was derived and the root mean square (RMS value was determined. Our results confirm that age has a significant influence on the texture of the trabecular bone and bone mineral density.

  16. Distal radius bone mineral density estimation using the filling factor of trabecular bone in the x-ray image.

    Science.gov (United States)

    Lee, Sooyeul; Jeong, Ji-Wook; Lee, Jeong Won; Yoo, Done-Sik; Kim, Seunghwan

    2006-01-01

    Osteoporosis is characterized by an abnormal loss of bone mineral content, which leads to a tendency to non-traumatic bone fractures or to structural deformations of bone. Thus, bone density measurement has been considered as a most reliable method to assess bone fracture risk due to osteoporosis. In past decades, X-ray images have been studied in connection with the bone mineral density estimation. However, the estimated bone mineral density from the X-ray image can undergo a relatively large accuracy or precision error. The most relevant origin of the accuracy or precision error may be unstable X-ray image acquisition condition. Thus, we focus our attentions on finding a bone mineral density estimation method that is relatively insensitive to the X-ray image acquisition condition. In this paper, we develop a simple technique for distal radius bone mineral density estimation using the trabecular bone filling factor in the X-ray image and apply the technique to the wrist X-ray images of 20 women. Estimated bone mineral density shows a high linear correlation with a dual-energy X-ray absorptiometry (r=0.87).

  17. Association of Trabecular Bone Score with Inflammation and Adiposity in Patients with Psoriasis: Effect of Adalimumab Therapy

    Directory of Open Access Journals (Sweden)

    José L. Hernández

    2016-01-01

    Full Text Available Studies on trabecular bone score (TBS in psoriasis are lacking. We aim to assess the association between TBS and inflammation, metabolic syndrome features, and serum adipokines in 29 nondiabetic patients with psoriasis without arthritis, before and after 6-month adalimumab therapy. For that purpose, adjusted partial correlations and stepwise multivariable linear regression analysis were performed. No correlation was found between TBS and disease severity. TBS was negatively associated with weight, BMI, waist perimeter, fat percentage, and systolic and diastolic blood pressure before and after adalimumab. After 6 months of therapy, a negative correlation between TBS and insulin resistance (p=0.02 and leptin (p=0.01 and a positive correlation with adiponectin were found (p=0.01. The best set of predictors for TBS values at baseline were female sex (p=0.015, age (p=0.05, and BMI (p=0.001. The best set of predictors for TBS following 6 months of biologic therapy were age (p=0.001, BMI (p<0.0001, and serum adiponectin levels (p=0.027. In conclusion, in nondiabetic patients with moderate-to-severe psoriasis, TBS correlates with metabolic syndrome features and inflammation. This association is still present after 6 months of adalimumab therapy. Moreover, serum adiponectin levels seem to be an independent variable related to TBS values, after adalimumab therapy.

  18. Association of Trabecular Bone Score with Inflammation and Adiposity in Patients with Psoriasis: Effect of Adalimumab Therapy.

    Science.gov (United States)

    Hernández, José L; López-Mejías, Raquel; Blanco, Ricardo; Pina, Trinitario; Ruiz, Sheila; Sierra, Isabel; Ubilla, Begoña; Mijares, Verónica; González-López, Marcos A; Armesto, Susana; Corrales, Alfonso; Pons, Enar; Fuentevilla, Patricia; González-Vela, Carmen; González-Gay, Miguel Á

    2016-01-01

    Studies on trabecular bone score (TBS) in psoriasis are lacking. We aim to assess the association between TBS and inflammation, metabolic syndrome features, and serum adipokines in 29 nondiabetic patients with psoriasis without arthritis, before and after 6-month adalimumab therapy. For that purpose, adjusted partial correlations and stepwise multivariable linear regression analysis were performed. No correlation was found between TBS and disease severity. TBS was negatively associated with weight, BMI, waist perimeter, fat percentage, and systolic and diastolic blood pressure before and after adalimumab. After 6 months of therapy, a negative correlation between TBS and insulin resistance (p = 0.02) and leptin (p = 0.01) and a positive correlation with adiponectin were found (p = 0.01). The best set of predictors for TBS values at baseline were female sex (p = 0.015), age (p = 0.05), and BMI (p = 0.001). The best set of predictors for TBS following 6 months of biologic therapy were age (p = 0.001), BMI (p < 0.0001), and serum adiponectin levels (p = 0.027). In conclusion, in nondiabetic patients with moderate-to-severe psoriasis, TBS correlates with metabolic syndrome features and inflammation. This association is still present after 6 months of adalimumab therapy. Moreover, serum adiponectin levels seem to be an independent variable related to TBS values, after adalimumab therapy.

  19. Bmp2 in osteoblasts of periosteum and trabecular bone links bone formation to vascularization and mesenchymal stem cells.

    Science.gov (United States)

    Yang, Wuchen; Guo, Dayong; Harris, Marie A; Cui, Yong; Gluhak-Heinrich, Jelica; Wu, Junjie; Chen, Xiao-Dong; Skinner, Charles; Nyman, Jeffry S; Edwards, James R; Mundy, Gregory R; Lichtler, Alex; Kream, Barbara E; Rowe, David W; Kalajzic, Ivo; David, Val; Quarles, Darryl L; Villareal, Demetri; Scott, Greg; Ray, Manas; Liu, S; Martin, James F; Mishina, Yuji; Harris, Stephen E

    2013-09-15

    We generated a new Bmp2 conditional-knockout allele without a neo cassette that removes the Bmp2 gene from osteoblasts (Bmp2-cKO(ob)) using the 3.6Col1a1-Cre transgenic model. Bones of Bmp2-cKO(ob) mice are thinner, with increased brittleness. Osteoblast activity is reduced as reflected in a reduced bone formation rate and failure to differentiate to a mature mineralizing stage. Bmp2 in osteoblasts also indirectly controls angiogenesis in the periosteum and bone marrow. VegfA production is reduced in Bmp2-cKO(ob) osteoblasts. Deletion of Bmp2 in osteoblasts also leads to defective mesenchymal stem cells (MSCs), which correlates with the reduced microvascular bed in the periosteum and trabecular bones. Expression of several MSC marker genes (α-SMA, CD146 and Angiopoietin-1) in vivo, in vitro CFU assays and deletion of Bmp2 in vitro in α-SMA(+) MSCs support our conclusions. Critical roles of Bmp2 in osteoblasts and MSCs are a vital link between bone formation, vascularization and mesenchymal stem cells.

  20. Increased strontium uptake in trabecular bone of ovariectomized calcium-deficient rats treated with strontium ranelate or strontium chloride.

    Science.gov (United States)

    Pemmer, Bernhard; Hofstaetter, Jochen G; Meirer, Florian; Smolek, Stephan; Wobrauschek, Peter; Simon, Rolf; Fuchs, Robyn K; Allen, Matthew R; Condon, Keith W; Reinwald, Susan; Phipps, Roger J; Burr, David B; Paschalis, Eleftherios P; Klaushofer, Klaus; Streli, Christina; Roschger, Paul

    2011-11-01

    Based on clinical trials showing the efficacy to reduce vertebral and non-vertebral fractures, strontium ranelate (SrR) has been approved in several countries for the treatment of postmenopausal osteoporosis. Hence, it is of special clinical interest to elucidate how the Sr uptake is influenced by dietary Ca deficiency as well as by the formula of Sr administration, SrR versus strontium chloride (SrCl(2)). Three-month-old ovariectomized rats were treated for 90 days with doses of 25 mg kg(-1) d(-1) and 150 mg kg(-1) d(-1) of SrR or SrCl(2) at low (0.1% Ca) or normal (1.19% Ca) Ca diet. Vertebral bone tissue was analysed by confocal synchrotron-radiation-induced micro X-ray fluorescence and by backscattered electron imaging. Principal component analysis and k-means clustering of the acquired elemental maps of Ca and Sr revealed that the newly formed bone exhibited the highest Sr fractions and that low Ca diet increased the Sr uptake by a factor of three to four. Furthermore, Sr uptake in bone of the SrCl(2)-treated animals was generally lower compared with SrR. The study clearly shows that inadequate nutritional calcium intake significantly increases uptake of Sr in serum as well as in trabecular bone matrix. This indicates that nutritional calcium intake as well as serum Ca levels are important regulators of any Sr treatment.

  1. Influence of estrogen deficiency and tibolone therapy on trabecular and cortical bone evaluated by computed radiography system in rats

    Energy Technology Data Exchange (ETDEWEB)

    Carvalho, Ana Carolina Bergmann de; Henriques, Helene Nara [Postgraduate Program in Pathology, Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil); Fernandes, Gustavo Vieira Oliveira [Postgraduate Program in Medical Sciences, Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil); Lima, Inaya; Oliveira, Davi Ferreira de; Lopes, Ricardo Tadeu [Nuclear Engineering Program, Federal University of Rio de Janeiro (UFRJ), RJ (Brazil); Pantaleao, Jose Augusto Soares [Maternal and Child Department, Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil); Granjeiro, Jose Mauro [Department of Cellular and Molecular Biology, Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil); Silva, Maria Angelica Guzman [Department of Pathology, Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil)

    2012-03-15

    Purpose: To verify the effects of tibolone administration on trabecular and cortical bone of ovariectomized female rats by computed radiography system (CRS). Methods: The experiment was performed on two groups of rats previously ovariectomized, one received tibolone (OVX+T) while the other did not (OVX), those groups were compared to a control group (C) not ovariectomized. Tibolone administration (1 mg/day) began thirty days after the ovariectomy and the treatment remained for five months. At last, the animals were euthanized and femurs and tibias collected. Computed radiographs of the bones were obtained and the digital images were used to determine the bone optical density and cortical thickness on every group. All results were statistically evaluated with significance set at P<0.05%. Results: Tibolone administration was shown to be beneficial only in the densitometric analysis of the femoral head, performing higher optical density compared to OVX. No difference was found in cortical bone thickness. Conclusion: Ovariectomy caused bone loss in the analyzed regions and tibolone administered in high doses over a long period showed not to be fully beneficial, but preserved bone mass in the femoral head. (author)

  2. Experiment list: SRX956390 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available SRX956390 hg19 DNase-seq DNase-Seq Others Trabecular meshwork cells NA 205484486,0....0,11.5,0 GSM1633692: TM rep1; Homo sapiens; DNase-Hypersensitivity source_name=postmortem donor tissue || ce...ll type=trabecular meshwork cells http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/eachData/bw/SRX956390.bw h

  3. Fast trabecular bone strength predictions of HR-pQCT and individual trabeculae segmentation-based plate and rod finite element model discriminate postmenopausal vertebral fractures.

    Science.gov (United States)

    Liu, X Sherry; Wang, Ji; Zhou, Bin; Stein, Emily; Shi, Xiutao; Adams, Mark; Shane, Elizabeth; Guo, X Edward

    2013-07-01

    Although high-resolution peripheral quantitative computed tomography (HR-pQCT) has advanced clinical assessment of trabecular bone microstructure, nonlinear microstructural finite element (µFE) prediction of yield strength using a HR-pQCT voxel model is impractical for clinical use due to its prohibitively high computational costs. The goal of this study was to develop an efficient HR-pQCT-based plate and rod (PR) modeling technique to fill the unmet clinical need for fast bone strength estimation. By using an individual trabecula segmentation (ITS) technique to segment the trabecular structure into individual plates and rods, a patient-specific PR model was implemented by modeling each trabecular plate with multiple shell elements and each rod with a beam element. To validate this modeling technique, predictions by HR-pQCT PR model were compared with those of the registered high-resolution micro-computed tomography (HR-µCT) voxel model of 19 trabecular subvolumes from human cadaveric tibia samples. Both the Young's modulus and yield strength of HR-pQCT PR models strongly correlated with those of µCT voxel models (r²  = 0.91 and 0.86). Notably, the HR-pQCT PR models achieved major reductions in element number (>40-fold) and computer central processing unit (CPU) time (>1200-fold). Then, we applied PR model µFE analysis to HR-pQCT images of 60 postmenopausal women with (n = 30) and without (n = 30) a history of vertebral fracture. HR-pQCT PR model revealed significantly lower Young's modulus and yield strength at the radius and tibia in fracture subjects compared to controls. Moreover, these mechanical measurements remained significantly lower in fracture subjects at both sites after adjustment for areal bone mineral density (aBMD) T-score at the ultradistal radius or total hip. In conclusion, we validated a novel HR-pQCT PR model of human trabecular bone against µCT voxel models and demonstrated its ability to discriminate vertebral fracture

  4. Effect of weight-bearing exercise and calcium supplement on cortical and trabecular bone in the proximal tibia metaphyseal- an experimental protocol in ovariectomized rats

    Directory of Open Access Journals (Sweden)

    Valliollah Dabidy Roshan1

    2009-01-01

    Full Text Available (Received 4 April, 2009; Accepted 17 June, 2009AbstractBackground and purpose: Osteoporotic fractures are much more common in older post-menopausal women and account for significant morbidity and mortality. Although age is an independent risk factor for fractures, bone micro-architecture is the predictor of subsequent fractures. Adequate calcium and Weight-bearing exercise are known to affect skeletal development, however, the effects of calcium supplement and treadmill endurance running on bone micro-architecture are not well known. The objective of this study was to determine the effects of treadmill endurance running training and calcium supplement, on micro-architectures of cortical and trabecular bone in the proximal tibia metaphyseal in ovariectomized Sprague Dawley rats.Materials and methods: Forty-three rats were randomly divided into endurance running training, calcium supplement, control, pre-test and base groups. The rats in the treadmill running group performed the progressive running exercise in 12 to 20 m/minutes for a total of 10 to 60 minutes, 5 times a week. Calcium group received ca supplement using Gavage (35 mg/kg/day for 8 weeks. After 8 weeks, micro-architecture parameters in the proximal tibia metaphyseal were measured by using a semi-automated image analysis system.Results: The ovariectomay was associated with a significant decrease in the trabecular volume and thickness, while separation insignificantly decreased in the cortical volume and thickness in the proximal tibia metaphyseal. The treadmill running exercise and calcium supplement significantly increased cortical or trabecular volume and also thickness and the trabecular separation compared with age-matched controls. Furthermore, the micro-architectures of cortical and trabecular bone in the proximal tibia metaphyseal was insignificant between the treadmill endurance running and calcium supplement groups.Conclusion: Skeletal benefits can be obtained by changes in

  5. Trabecular Structure Quantified With the MRI-Based Virtual Bone Biopsy in Postmenopausal Women Contributes to Vertebral Deformity Burden Independent of Areal Vertebral BMD

    Science.gov (United States)

    Ladinsky, Glenn A; Vasilic, Branimir; Popescu, Andra M; Wald, Michael; Zemel, Babette S; Snyder, Peter J; Loh, Louise; Song, Hee Kwon; Saha, Punam K; Wright, Alexander C; Wehrli, Felix W

    2008-01-01

    In postmenopausal women with a wide range of vertebral deformities, MRI-based structural measures of topology and scale at the distal radius are shown to account for as much as 30% of vertebral deformity, independent of integral vertebral BMD. Introduction Trabecular bone architecture has been postulated to contribute to overall bone strength independent of vertebral BMD measured by DXA. However, there has thus far been only sparse in vivo evidence to support this hypothesis. Materials and Methods Postmenopausal women, 60–80 yr of age, were screened by DXA, and those with T-scores at either the hip or spine falling within the range of −2.5 ± 1.0 were studied with the MRI-based virtual bone biopsy, along with heel broadband ultrasound absorption and pQCT of the tibia. The data from 98 subjects meeting the enrollment criteria were subjected to μMRI at the distal tibia and radius, and measures of topology and scale of the trabecular bone network were computed. A spinal deformity index (SDI) was obtained from morphometric measurements in midline sagittal MR images of the thoracic and lumbar spine to evaluate associations between structure and deformity burden. Results A number of structural indices obtained at the distal radius were correlated with the SDI. Among these were the topological surface density (a measure of trabecular plates) and trabecular bone volume fraction, which were inversely correlated with SDI (p < 0.0001). Combinations of two structural parameters accounted for up to 30% of the variation in SDI (p < 0.0001) independent of spinal BMD, which was not significantly correlated. pQCT trabecular BMD was also weakly associated, whereas broadband ultrasound absorption was not. No significant association between SDI and structural indices were found at the tibia. Conclusions Structural measures at the distal radius obtained in vivo by μMRI explained a significant portion of the variation in total spinal deformity burden in postmenopausal women

  6. Acetabular trabecular direction between different species%不同物种髋臼的骨小梁方向*☆

    Institute of Scientific and Technical Information of China (English)

    孙剑伟; 颜冰珊; 尹望平; 张春才

    2013-01-01

      BACKGROUND: Some studies have shown that the morphological structure of bone is closely related with the stress environment. But the human walking upright movement may affect the direction of the acetabular trabecular bone. OBJECTIVE: To observe the differences of acetabular bone direction between different species. METHODS: Hip bones of human and rhesus monkey selected from Department of Anatomy, Second Military Medical University and the Shandong University School of Life Science were scanned by X-ray under the same conditions of shooting. The images were imported into Imagine pro plus 6.0 and transferred by fast fourier transform, then obtained the spectrum value of 0°-180° to calculate the number of trabeculae in a certain direction. RESULTS AND CONCLUSION: The human had highest spectrum value in 0° and 90° which were in accordance with Ilioischial bundle and sacropubic bundle. Rhesus monkeys distributed dispersedly and there was no obvious peak. The human trabecular in acetabular region mainly distributed along 90°-180° which were in accordance with Ilioischial bundle and sacropubic bundle, this indicated that there was relationship between Ilioischial bundle and human walking pattern.%  背景:有研究认为骨的形态结构与其所处的应力环境密切相关。由于人类直立行走的运动方式,可能会影响髋臼骨小梁的方向。目的:观察不同物种髋臼骨小梁方向的差异。方法:X射线观察由解放军第二军医大学解剖教研室和山东大学生命科学院提供的成人双侧髋骨干燥标本和成年恒河猴髋骨标本,将采集到的图像输入 Imagine pro plus 6.0,经快速傅里叶变换后,得出0°-180°的频谱值,计量不同的角度骨小梁的数量。结果与结论:人类髋骨在0°及90°频谱值最大,与骶耻束与髂坐束的方向符合。而恒河猴髋骨的频谱值分布较为弥散,没有明显的峰值。说明人类

  7. A prospective 3-year follow-up trial of implantation of two trabecular microbypass stents in open-angle glaucoma

    Directory of Open Access Journals (Sweden)

    Donnenfeld ED

    2015-11-01

    Full Text Available Eric D Donnenfeld,1 Kerry D Solomon,2 Lilit Voskanyan,3 David F Chang,4 Thomas W Samuelson,5 Iqbal Ike K Ahmed,6 L Jay Katz7 1Ophthalmic Consultants of Long Island, Rockville Centre, NY, 2Carolina Eyecare Physicians, Mt Pleasant, SC, USA; 3S.V. Malayan Ophthalmology Centre, Yerevan, Armenia; 4Altos Eye Physicians, Los Altos, CA, 5Minnesota Eye Consultants, Minneapolis, MN, USA; 6University of Toronto, Toronto, ON, Canada; 7Wills Eye Hospital, Jefferson Medical College, Philadelphia, PA, USA Purpose: To evaluate 3-year safety and intraocular pressure (IOP following two trabecular microbypass stents in phakic and pseudophakic subjects with open-angle glaucoma (OAG not controlled on preoperative medication. Patients and methods: In this prospective pilot study, phakic or pseudophakic subjects with OAG and IOP between 18 mmHg and 30 mmHg on one preoperative topical ocular hypotensive medication underwent medication washout. Thirty-nine qualified subjects with preoperative unmedicated IOP ≥22 mmHg and ≤38 mmHg received two stents. Postoperative examinations were scheduled at Day 1, Week 1, Months 1, 3, 6, and 12, and semiannually through Month 60. Ocular hypotensive medication was considered if postoperative IOP exceeded 21 mmHg. IOP, medication use, and safety were assessed at each visit. Subject follow-up through Month 36 was completed. Results: Thirty-six eyes (92.3%; 95% confidence interval [CI] 79.1%, 98.4% achieved the primary efficacy end point of Month 12 reduction in IOP ≥20% from baseline (unmedicated IOP without ocular hypotensive medication. Four subjects required medication during the Month 36 follow-up period. Mean IOP at 36 months for subjects not taking medication was 15.2 mmHg. At 36 months, subjects sustained mean IOP decrease of 9.1±2.7 mmHg (95% CI 8.0 mmHg, 10.14 mmHg, or 37% IOP reduction, from unmedicated baseline IOP. Compared to preoperative medicated IOP, subjects had mean reduction at Month 36 of 5.5±2

  8. Epiphyseal abnormalities, trabecular bone loss and articular chondrocyte hypertrophy develop in the long bones of postnatal Ext1-deficient mice.

    Science.gov (United States)

    Sgariglia, Federica; Candela, Maria Elena; Huegel, Julianne; Jacenko, Olena; Koyama, Eiki; Yamaguchi, Yu; Pacifici, Maurizio; Enomoto-Iwamoto, Motomi

    2013-11-01

    Long bones are integral components of the limb skeleton. Recent studies have indicated that embryonic long bone development is altered by mutations in Ext genes and consequent heparan sulfate (HS) deficiency, possibly due to changes in activity and distribution of HS-binding/growth plate-associated signaling proteins. Here we asked whether Ext function is continuously required after birth to sustain growth plate function and long bone growth and organization. Compound transgenic Ext1(f/f);Col2CreERT mice were injected with tamoxifen at postnatal day 5 (P5) to ablate Ext1 in cartilage and monitored over time. The Ext1-deficient mice exhibited growth retardation already by 2weeks post-injection, as did their long bones. Mutant growth plates displayed a severe disorganization of chondrocyte columnar organization, a shortened hypertrophic zone with low expression of collagen X and MMP-13, and reduced primary spongiosa accompanied, however, by increased numbers of TRAP-positive osteoclasts at the chondro-osseous border. The mutant epiphyses were abnormal as well. Formation of a secondary ossification center was significantly delayed but interestingly, hypertrophic-like chondrocytes emerged within articular cartilage, similar to those often seen in osteoarthritic joints. Indeed, the cells displayed a large size and round shape, expressed collagen X and MMP-13 and were surrounded by an abundant Perlecan-rich pericellular matrix not seen in control articular chondrocytes. In addition, ectopic cartilaginous outgrowths developed on the lateral side of mutant growth plates over time that resembled exostotic characteristic of children with Hereditary Multiple Exostoses, a syndrome caused by Ext mutations and HS deficiency. In sum, the data do show that Ext1 is continuously required for postnatal growth and organization of long bones as well as their adjacent joints. Ext1 deficiency elicits defects that can occur in human skeletal conditions including trabecular bone loss

  9. Reproducibility of trabecular bone score with different scan modes using dual-energy X-ray absorptiometry: a phantom study

    Energy Technology Data Exchange (ETDEWEB)

    Bandirali, Michele; Messina, Carmelo [Universita degli Studi di Milano, Scuola di Specializzazione in Radiodiagnostica, Milano (Italy); Di Leo, Giovanni [Unita di Radiologia, IRCCS Policlinico San Donato, San Donato Milanese (Italy); Pastor Lopez, Maria Juana; Ulivieri, Fabio M. [Servizio di Medicina Nucleare, Ospedale Maggiore, Mineralometria Ossea Computerizzata e Ambulatorio Malattie Metabolismo Minerale e Osseo, Milano (Italy); Mai, Alessandro [Universita degli Studi di Milano, Tecniche di Radiologia Medica, per Immagini e Radioterapia, Milano (Italy); Sardanelli, Francesco [Unita di Radiologia, IRCCS Policlinico San Donato, San Donato Milanese (Italy); Universita degli Studi di Milano, Dipartimento di Scienze Biomediche per la Salute, San Donato Milanese (Italy)

    2014-08-12

    The trabecular bone score (TBS) accounts for the bone microarchitecture and is calculated on dual-energy X-ray absorptiometry (DXA). We estimated the reproducibility of the TBS using different scan modes compared to the reproducibility bone mineral density (BMD). A spine phantom was used with a Hologic QDR-Discovery A densitometer. For each scan mode [fast array, array, high definition (HD)], 25 scans were automatically performed without phantom repositioning; a further 25 scans were performed with phantom repositioning. For each scan, the TBS was obtained. The coefficient of variation (CoV) was calculated as the ratio between standard deviation and mean; percent least significant change (LSC%) as 2.8 x CoV; reproducibility as the complement to 100 % of LSC%. Differences among scan modes were assessed using ANOVA. Without phantom repositioning, the mean TBS (mm{sup -1}) was: 1.352 (fast array), 1.321 (array), and 1.360 (HD); with phantom repositioning, it was 1.345, 1.332, and 1.362, respectively. Reproducibility of the TBS without phantom repositioning was 97.7 % (fast array), 98.3 % (array), and 98.2 % (HD); with phantom repositioning, it was 97.9 %, 98.7 %, and 98.4 %, respectively. LSC% was ≤2.26 %. Differences among scan modes were all statistically significant (p ≤ 0.019). Reproducibility of BMD was 99.1 % with all scan modes, while LSC% was from 0.86 % to 0.91 %. Reproducibility error of the TBS was 2-3-fold higher than that of BMD. Although statistically significant, differences in TBS among scan modes were within the highest LSC%. Thus, the three scan modes can be considered interchangeable. (orig.)

  10. Densitometer-Specific Differences in the Correlation Between Body Mass Index and Lumbar Spine Trabecular Bone Score.

    Science.gov (United States)

    Mazzetti, Gillian; Berger, Claudie; Leslie, William D; Hans, Didier; Langsetmo, Lisa; Hanley, David A; Kovacs, Christopher S; Prior, Jerrilyn C; Kaiser, Stephanie M; Davison, K Shawn; Josse, Robert; Papaioannou, Alexandra; Adachi, Jonathan R; Goltzman, David; Morin, Suzanne N

    2016-12-26

    Trabecular bone score (TBS) is a gray-level texture measure derived from lumbar spine dual-energy X-ray absorptiometry (DXA) images that predicts fractures independent of bone mineral density (BMD). Increased abdominal soft tissue in individuals with elevated body mass index (BMI) absorbs more X-rays during image acquisition for BMD measurement and must be accommodated by the TBS algorithm. We aimed to determine if the relationship between BMI and TBS varied between 2 major manufacturers' densitometers, because different densitometers accommodate soft tissues differently. We identified 1919 women and 811 men, participants of the Canadian Multicentre Osteoporosis Study, aged ≥40 yr with lumbar spine DXA scans acquired on GE Lunar (4 centers) or Hologic (3 centers) densitometers at year 10 of follow-up. TBS was calculated for L1-L4 (TBS iNsight® software, version 2.1). A significant negative correlation between TBS and BMI was observed when TBS measurements were performed on Hologic densitometers in men (Pearson r = -0.36, p Pearson r = -0.33, p correlations were not seen when TBS was measured on GE Lunar densitometers (Pearson r = 0.00 in men, Pearson r = -0.02 in women). Age-adjusted linear regression models confirmed significant interactions between BMI and densitometer manufacturer for both men and women (p correlations were observed between BMD and BMI on both Hologic and GE Lunar densitometers in men and women. In conclusion, BMI significantly affects TBS values in men and women when measured on Hologic but not GE Lunar densitometers. This finding has implications for clinical and research applications of TBS, especially when TBS is measured sequentially on DXA densitometers from different manufacturers or when results from different machines are pooled for analysis.

  11. Trabecular bone characterization on the continuum of plates and rods using in vivo MR imaging and volumetric topological analysis.

    Science.gov (United States)

    Chen, Cheng; Jin, Dakai; Liu, Yinxiao; Wehrli, Felix W; Chang, Gregory; Snyder, Peter J; Regatte, Ravinder R; Saha, Punam K

    2016-09-21

    Osteoporosis is associated with increased risk of fractures, which is clinically defined by low bone mineral density. Increasing evidence suggests that trabecular bone (TB) micro-architecture is an important determinant of bone strength and fracture risk. We present an improved volumetric topological analysis algorithm based on fuzzy skeletonization, results of its application on in vivo MR imaging, and compare its performance with digital topological analysis. The new VTA method eliminates data loss in the binarization step and yields accurate and robust measures of local plate-width for individual trabeculae, which allows classification of TB structures on the continuum between perfect plates and rods. The repeat-scan reproducibility of the method was evaluated on in vivo MRI of distal femur and distal radius, and high intra-class correlation coefficients between 0.93 and 0.97 were observed. The method's ability to detect treatment effects on TB micro-architecture was examined in a 2 years testosterone study on hypogonadal men. It was observed from experimental results that average plate-width and plate-to-rod ratio significantly improved after 6 months and the improvement was found to continue at 12 and 24 months. The bone density of plate-like trabeculae was found to increase by 6.5% (p  =  0.06), 7.2% (p  =  0.07) and 16.2% (p  =  0.003) at 6, 12, 24 months, respectively. While the density of rod-like trabeculae did not change significantly, even at 24 months. A comparative study showed that VTA has enhanced ability to detect treatment effects in TB micro-architecture as compared to conventional method of digital topological analysis for plate/rod characterization in terms of both percent change and effect-size.

  12. Reproducibility of trabecular bone score with different scan modes using dual-energy X-ray absorptiometry: a phantom study.

    Science.gov (United States)

    Bandirali, Michele; Di Leo, Giovanni; Messina, Carmelo; Pastor Lopez, Maria Juana; Mai, Alessandro; Ulivieri, Fabio M; Sardanelli, Francesco

    2015-04-01

    The trabecular bone score (TBS) accounts for the bone microarchitecture and is calculated on dual-energy X-ray absorptiometry (DXA). We estimated the reproducibility of the TBS using different scan modes compared to the reproducibility bone mineral density (BMD). A spine phantom was used with a Hologic QDR-Discovery A densitometer. For each scan mode [fast array, array, high definition (HD)], 25 scans were automatically performed without phantom repositioning; a further 25 scans were performed with phantom repositioning. For each scan, the TBS was obtained. The coefficient of variation (CoV) was calculated as the ratio between standard deviation and mean; percent least significant change (LSC%) as 2.8 × CoV; reproducibility as the complement to 100 % of LSC%. Differences among scan modes were assessed using ANOVA. Without phantom repositioning, the mean TBS (mm(-1)) was: 1.352 (fast array), 1.321 (array), and 1.360 (HD); with phantom repositioning, it was 1.345, 1.332, and 1.362, respectively. Reproducibility of the TBS without phantom repositioning was 97.7 % (fast array), 98.3 % (array), and 98.2 % (HD); with phantom repositioning, it was 97.9 %, 98.7 %, and 98.4 %, respectively. LSC% was ≤ 2.26 %. Differences among scan modes were all statistically significant (p ≤ 0.019). Reproducibility of BMD was 99.1 % with all scan modes, while LSC% was from 0.86 % to 0.91 %. Reproducibility error of the TBS was 2-3-fold higher than that of BMD. Although statistically significant, differences in TBS among scan modes were within the highest LSC%. Thus, the three scan modes can be considered interchangeable.

  13. Volumetric topological analysis: a novel method for trabecular bone characterization on the continuum between plates and rods

    Science.gov (United States)

    Saha, Punam K.; Xu, Yan; Liang, Guoyuan; Duan, Hong

    2009-02-01

    Trabecular bone (TB) is a complex quasi-random network of interconnected struts and plates. TB constantly remodels to adapt dynamically to the stresses to which it is subjected (Wolff's Law). In osteoporosis, this dynamic equilibrium between bone formation and resorption is perturbed, leading to bone loss and structural deterioration, both increasing fracture risk. Bone's mechanical competence can only be partly explained by variations in bone mineral density, which led to the notion of bone structural quality. Previously, we developed digital topological analysis or DTA which classifies plates, rods, profiles, edges and junctions in a TB skeletal representation. Although the method has become quite popular, a major limitation is that DTA produces hard classifications only, failing to distinguish between narrow and wide plates. Here, we present a new method called volumetric topological analysis or VTA for quantification of regional topology in complex quasi-random TB networks. At each TB voxel, the method uniquely classifies the topology on the continuum between perfect plates and rods. Therefore, the method is capable of detecting early alterations of trabeculae from plates to rods according to the known etiology of osteoporotic bone loss. Here, novel ideas of geodesic distance transform, geodesic scale and feature propagation have been introduced and combined with DTA and fuzzy distance transform methods conceiving the new VTA technology. The method has been applied to MDCT and μCT images of a cadaveric distal tibia specimen and the results have been quantitatively evaluated. Specifically, intra- and inter-modality reproducibility of the method has been examined and the results are found very promising.

  14. Hyalinizing trabecular tumor of the thyroid: Diagnosed of a rare tumor using ultrasonography, cytology, and intraoperative frozen sections

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Hyun Sik; Kim, Eun Kyung; Kwak, Jin Young; Moon, Hee Jung; Yoon, Jung Hyun [Dept. of Radiology, Severance Hospital, Research Institute of Radiological Science, Yonsei University, College of Medicine, Seoul (Korea, Republic of); Park, Cheol Keun; Son, Eun Ju [Gangnam Severance Hospital, Yonsei University, College of Medicine, Seoul (Korea, Republic of)

    2016-03-15

    The goal of this study was to evaluate the clinicopathological and imaging features of thyroid nodules surgically diagnosed as hyaline trabecular tumor (HTT), and to assess the role of cytology and frozen sections (FS) in the diagnosis of HTT. This study included 21 thyroid nodules in 21 patients treated from August 2005 to March 2015 (mean age, 53.3 years) who were either diagnosed as HTT or had HTT suggested as a possible diagnosis based on cytology, FS, or the final pathology report. Patients' medical records were retrospectively reviewed for cytopathologic results and outcomes during the course of follow-up. Sonograms were reviewed and categorized. Twelve nodules from 12 patients were surgically confirmed as HTT. Ultrasonography (US)-guided fine needle aspiration (FNA) was performed on 11 nodules, of which six (54.5%) were papillary thyroid carcinoma (PTC) or suspicious for PTC and three (27.3%) were HTT or suspicious for HTT. Intraoperative FS suggested the possibility of HTT in seven nodules, of which four (57.1%) were confirmed as HTT. US-FNA suggested the diagnosis of HTT in 10 nodules, of which three (30.0%) were confirmed as HTT. Common US features of the 12 pathologically confirmed cases of HTT were hypoechogenicity or marked hypoechogenicity (83.4%), absence of calcifications (91.7%), parallel shape (100.0%), presence of vascularity (75.0%), and probable benignity (58.3%). HTT should be included in the differential diagnosis of solid tumors with hypoechogenicity or marked hypoechogenicity and otherwise benign US features that have been diagnosed as PTC through cytology.

  15. Hyalinizing trabecular tumor of the thyroid: diagnosis of a rare tumor using ultrasonography, cytology, and intraoperative frozen sections

    Directory of Open Access Journals (Sweden)

    Hyunsik Jang

    2016-04-01

    Full Text Available Purpose: The goal of this study was to evaluate the clinicopathological and imaging features of thyroid nodules surgically diagnosed as hyaline trabecular tumor (HTT, and to assess the role of cytology and frozen sections (FS in the diagnosis of HTT. Methods: This study included 21 thyroid nodules in 21 patients treated from August 2005 to March 2015 (mean age, 53.3 years who were either diagnosed as HTT or had HTT suggested as a possible diagnosis based on cytology, FS, or the final pathology report. Patients’ medical records were retrospectively reviewed for cytopathologic results and outcomes during the course of follow-up. Sonograms were reviewed and categorized. Results: Twelve nodules from 12 patients were surgically confirmed as HTT. Ultrasonography (US-guided fine needle aspiration (FNA was performed on 11 nodules, of which six (54.5% were papillary thyroid carcinoma (PTC or suspicious for PTC and three (27.3% were HTT or suspicious for HTT. Intraoperative FS suggested the possibility of HTT in seven nodules, of which four (57.1% were confirmed as HTT. US-FNA suggested the diagnosis of HTT in 10 nodules, of which three (30.0% were confirmed as HTT. Common US features of the 12 pathologically confirmed cases of HTT were hypoechogenicity or marked hypoechogenicity (83.4%, absence of calcifications (91.7%, parallel shape (100.0%, presence of vascularity (75.0%, and probable benignity (58.3%. Conclusion: HTT should be included in the differential diagnosis of solid tumors with hypoechogenicity or marked hypoechogenicity and otherwise benign US features that have been diagnosed as PTC through cytology.

  16. Increased trabecular bone and improved biomechanics in an osteocalcin-null rat model created by CRISPR/Cas9 technology

    Science.gov (United States)

    Lambert, Laura J.; Challa, Anil K.; Niu, Aidi; Zhou, Lihua; Tucholski, Janusz; Johnson, Maria S.; Nagy, Tim R.; Eberhardt, Alan W.; Estep, Patrick N.; Kesterson, Robert A.

    2016-01-01

    ABSTRACT Osteocalcin, also known as bone γ-carboxyglutamate protein (Bglap), is expressed by osteoblasts and is commonly used as a clinical marker of bone turnover. A mouse model of osteocalcin deficiency has implicated osteocalcin as a mediator of changes to the skeleton, endocrine system, reproductive organs and central nervous system. However, differences between mouse and human osteocalcin at both the genome and protein levels have challenged the validity of extrapolating findings from the osteocalcin-deficient mouse model to human disease. The rat osteocalcin (Bglap) gene locus shares greater synteny with that of humans. To further examine the role of osteocalcin in disease, we created a rat model with complete loss of osteocalcin using the CRISPR/Cas9 system. Rat osteocalcin was modified by injection of CRISPR/Cas9 mRNA into the pronuclei of fertilized single cell Sprague-Dawley embryos, and animals were bred to homozygosity and compound heterozygosity for the mutant alleles. Dual-energy X-ray absorptiometry (DXA), glucose tolerance testing (GTT), insulin tolerance testing (ITT), microcomputed tomography (µCT), and a three-point break biomechanical assay were performed on the excised femurs at 5 months of age. Complete loss of osteocalcin resulted in bones with significantly increased trabecular thickness, density and volume. Cortical bone volume and density were not increased in null animals. The bones had improved functional quality as evidenced by an increase in failure load during the biomechanical stress assay. Differences in glucose homeostasis were observed between groups, but there were no differences in body weight or composition. This rat model of complete loss of osteocalcin provides a platform for further understanding the role of osteocalcin in disease, and it is a novel model of increased bone formation with potential utility in osteoporosis and osteoarthritis research. PMID:27483347

  17. Improved bone anchorage of hydroxypatite coated implants compared with tricalcium-phosphate coated implants in trabecular bone in dogs.

    Science.gov (United States)

    Lind, M; Overgaard, S; Bünger, C; Søballe, K

    1999-05-01

    Tricalcium phosphate (TCP) and hydroxyapatite (HA) ceramic coatings are bioactive coatings that have been shown to stimulate bone apposition onto ceramic-coated implants. TCP and HA ceramics have well-documented differences in physical properties, but both types of ceramics are used for stimulation of bone ongrowth to cementless endo-prosthetic components clinically. However, little is known about the difference in osteoconductive properties between these coatings when inserted into trabecular bone in a controlled experimental situation. Unloaded cylindrical gritblasted titanium (Ti-6A1-4V) implants (6 x 10 mm) coated with either hydroxyapatite (HA) or tricalcium phosphate (TCP) ceramic were inserted into the proximal humerus of 20 skeletally mature dogs. The implants were initially surrounded by a 2 mm gap. Each animal received one HA-coated implant and one TCP-coated implant. All dogs were sacrificed 6 weeks after surgery. Results were evaluated by histomorphometry and mechanical push-out test. Push-out tests demonstrated that HA-coated implants were 10-fold stronger fixated in comparison to TCP-coated implant. Bone ongrowth was significantly higher for HA-coated implants compared to TCP-coated implants. Bone volume in the gap showed a tendency to less bone volume around HA-coated implants compared to TCP-coated implants but this difference was insignificant. As expected almost all of the TCP coating were resorbed after 6 weeks and almost none of the HA coating. HA-coated implants with a grit-blasted surface provide a favorable early mechanical implant anchorage most likely due to superior ceramic stability compared to TCP-coated implants.

  18. Increased trabecular bone and improved biomechanics in an osteocalcin-null rat model created by CRISPR/Cas9 technology

    Directory of Open Access Journals (Sweden)

    Laura J. Lambert

    2016-10-01

    Full Text Available Osteocalcin, also known as bone γ-carboxyglutamate protein (Bglap, is expressed by osteoblasts and is commonly used as a clinical marker of bone turnover. A mouse model of osteocalcin deficiency has implicated osteocalcin as a mediator of changes to the skeleton, endocrine system, reproductive organs and central nervous system. However, differences between mouse and human osteocalcin at both the genome and protein levels have challenged the validity of extrapolating findings from the osteocalcin-deficient mouse model to human disease. The rat osteocalcin (Bglap gene locus shares greater synteny with that of humans. To further examine the role of osteocalcin in disease, we created a rat model with complete loss of osteocalcin using the CRISPR/Cas9 system. Rat osteocalcin was modified by injection of CRISPR/Cas9 mRNA into the pronuclei of fertilized single cell Sprague-Dawley embryos, and animals were bred to homozygosity and compound heterozygosity for the mutant alleles. Dual-energy X-ray absorptiometry (DXA, glucose tolerance testing (GTT, insulin tolerance testing (ITT, microcomputed tomography (µCT, and a three-point break biomechanical assay were performed on the excised femurs at 5 months of age. Complete loss of osteocalcin resulted in bones with significantly increased trabecular thickness, density and volume. Cortical bone volume and density were not increased in null animals. The bones had improved functional quality as evidenced by an increase in failure load during the biomechanical stress assay. Differences in glucose homeostasis were observed between groups, but there were no differences in body weight or composition. This rat model of complete loss of osteocalcin provides a platform for further understanding the role of osteocalcin in disease, and it is a novel model of increased bone formation with potential utility in osteoporosis and osteoarthritis research.

  19. The combined effects of soya isoflavones and resistant starch on equol production and trabecular bone loss in ovariectomised mice.

    Science.gov (United States)

    Tousen, Yuko; Matsumoto, Yu; Matsumoto, Chiho; Nishide, Yoriko; Nagahata, Yuya; Kobayashi, Isao; Ishimi, Yoshiko

    2016-07-01

    Equol is a metabolite of the soya isoflavone (ISO) daidzein that is produced by intestinal microbiota. Equol has greater oestrogenic activity compared with other ISO, and it prevents bone loss in postmenopausal women. Resistant starch (RS), which has a prebiotic activity and is a dietary fibre, was reported to promote equol production. Conversely, the intestinal microbiota is reported to directly regulate bone health by reducing inflammatory cytokine levels and T-lymphocytes in bone. The present study evaluated the combined effects of diet supplemented with ISO and RS on intestinal microbiota, equol production, bone mineral density (BMD) and inflammatory gene expression in the bone marrow of ovariectomised (OVX) mice. Female ddY strain mice, aged 8 weeks, were either sham-operated (Sham, n 7) or OVX. OVX mice were randomly divided into the following four groups (seven per group): OVX control (OVX); OVX fed 0·05 % ISO diet (OVX+ISO); OVX fed 9 % RS diet (OVX+RS); and OVX fed 0·05 % ISO- and 9 % RS diet (OVX+ISO+RS). After 6 weeks, treatment with the combination of ISO and RS increased equol production, prevented the OVX-induced decline in trabecular BMD in the distal femur by modulating the enteric environment and altered OVX-induced inflammation-related gene expression in the bone marrow. However, there were no significant differences in bone parameters between the ISO+RS and ISO-alone groups in OVX mice. Our findings suggest that the combination of ISO and RS might alter intestinal microbiota and immune status in the bone marrow, resulting in attenuated bone resorption in OVX mice.

  20. Urine culture

    Science.gov (United States)

    Culture and sensitivity - urine ... when urinating. You also may have a urine culture after you have been treated for an infection. ... when bacteria or yeast are found in the culture. This likely means that you have a urinary ...

  1. Safeguards Culture

    Energy Technology Data Exchange (ETDEWEB)

    Frazar, Sarah L.; Mladineo, Stephen V.

    2012-07-01

    The concepts of nuclear safety and security culture are well established; however, a common understanding of safeguards culture is not internationally recognized. Supported by the National Nuclear Security Administration, the authors prepared this report, an analysis of the concept of safeguards culture, and gauged its value to the safeguards community. The authors explored distinctions between safeguards culture, safeguards compliance, and safeguards performance, and evaluated synergies and differences between safeguards culture and safety/security culture. The report concludes with suggested next steps.

  2. Organizational Culture

    Directory of Open Access Journals (Sweden)

    Adrian HUDREA

    2006-02-01

    Full Text Available Cultural orientations of an organization can be its greatest strength, providing the basis for problem solving, cooperation, and communication. Culture, however, can also inhibit needed changes. Cultural changes typically happen slowly – but without cultural change, many other organizational changes are doomed to fail. The dominant culture of an organization is a major contributor to its success. But, of course, no organizational culture is purely one type or another. And the existence of secondary cultures can provide the basis for change. Therefore, organizations need to understand the cultural environments and values.

  3. In vivo application of 3D-line skeleton graph analysis (LSGA) technique with high-resolution magnetic resonance imaging of trabecular bone structure.

    Science.gov (United States)

    Pothuaud, Laurent; Newitt, David C; Lu, Ying; MacDonald, Brian; Majumdar, Sharmila

    2004-05-01

    Over the last several years magnetic resonance (MR) imaging has emerged as a means of measuring in vivo 3D trabecular bone structure. In particular, MR based diagnosis could be used to complement standard bone mineral density (BMD) methods for assessing osteoporosis and evaluating longitudinal changes. The aim of this study was to demonstrate the feasibility of using the 3D-LSGA technique for the evaluation of trabecular bone structure of high-resolution MR images, particularly for assessing longitudinal changes, in vivo. First, the reproducibility of topological 3D-LSGA based measurements was evaluated in a set of seven volunteers, and coefficients of variations ranged from 3.5% to 6%. Second, high-resolution MR images of the radius in 30 postmenopausal women from a placebo controlled drug study (Idoxifene), divided into placebo ( n=9) and treated ( n=21) groups, were obtained at baseline (BL) and after 1 year of treatment (follow-up, FU). In addition, dual X-ray absorptiometry (DXA) measures of BMD were obtained in the distal radius. Standard morphological measurements based on the mean intercept length (MIL) technique as well as 3D-LSGA based measurements were applied to the 3D MR images. Significant changes from BL to FU were detected, in the treated group, using the topological 3D-LSGA based measurements, morphological measures of volume of connected trabeculae and App Tb.N from MIL analysis. The duration of the study was short, and the number of patients remaining in the study was small, hence these results cannot be interpreted with regard to a true therapeutic response. Furthermore, the site (wrist) and the drug (idoxifene) are not optimal for follow-up study. However, this paper demonstrated the feasibility of using 3D-LSGA based evaluation coupled with in vivo high-resolution MR imaging as a complementary approach for the monitoring of trabecular bone changes in individual subjects.

  4. Mechanical Loading Synergistically Increases Trabecular Bone Volume and Improves Mechanical Properties in the Mouse when BMP Signaling Is Specifically Ablated in Osteoblasts.

    Directory of Open Access Journals (Sweden)

    Ayaka Iura

    Full Text Available Bone homeostasis is affected by several factors, particularly mechanical loading and growth factor signaling pathways. There is overwhelming evidence to validate the importance of these signaling pathways, however, whether these signals work synergistically or independently to contribute to proper bone maintenance is poorly understood. Weight-bearing exercise increases mechanical load on the skeletal system and can improves bone quality. We previously reported that conditional knockout (cKO of Bmpr1a, which encodes one of the type 1 receptors for Bone Morphogenetic Proteins (BMPs, in an osteoblast-specific manner increased trabecular bone mass by suppressing osteoclastogenesis. The cKO bones also showed increased cortical porosity, which is expected to impair bone mechanical properties. Here, we evaluated the impact of weight-bearing exercise on the cKO bone phenotype to understand interactions between mechanical loading and BMP signaling through BMPR1A. Male mice with disruption of Bmpr1a induced at 9 weeks of age, exercised 5 days per week on a motor-driven treadmill from 11 to 16 weeks of age. Trabecular bone volume in cKO tibia was further increased by exercise, whereas exercise did not affect the trabecular bone in the control genotype group. This finding was supported by decreased levels of osteoclasts in the cKO tibiae. The cortical porosity in the cKO bones showed a marginally significant decrease with exercise and approached normal levels. Exercise increased ductility and toughness in the cKO bones. Taken together, reduction in BMPR1A signaling may sensitize osteoblasts for mechanical loading to improve bone mechanical properties.

  5. 3D Porous Architecture of Stacks of β-TCP Granules Compared with That of Trabecular Bone: A microCT, Vector Analysis, and Compression Study.

    Science.gov (United States)

    Chappard, Daniel; Terranova, Lisa; Mallet, Romain; Mercier, Philippe

    2015-01-01

    The 3D arrangement of porous granular biomaterials usable to fill bone defects has received little study. Granular biomaterials occupy 3D space when packed together in a manner that creates a porosity suitable for the invasion of vascular and bone cells. Granules of beta-tricalcium phosphate (β-TCP) were prepared with either 12.5 or 25 g of β-TCP powder in the same volume of slurry. When the granules were placed in a test tube, this produced 3D stacks with a high (HP) or low porosity (LP), respectively. Stacks of granules mimic the filling of a bone defect by a surgeon. The aim of this study was to compare the porosity of stacks of β-TCP granules with that of cores of trabecular bone. Biomechanical compression tests were done on the granules stacks. Bone cylinders were prepared from calf tibia plateau, constituted high-density (HD) blocks. Low-density (LD) blocks were harvested from aged cadaver tibias. Microcomputed tomography was used on the β-TCP granule stacks and the trabecular bone cores to determine porosity and specific surface. A vector-projection algorithm was used to image porosity employing a frontal plane image, which was constructed line by line from all images of a microCT stack. Stacks of HP granules had porosity (75.3 ± 0.4%) and fractal lacunarity (0.043 ± 0.007) intermediate between that of HD (respectively 69.1 ± 6.4%, p TCP granules than bone trabecule. Stacks of HP granules represent a scaffold that resembles trabecular bone in its porous microarchitecture.

  6. Synchrotron radiation micro-CT at the micrometer scale for the analysis of the three-dimensional morphology of microcracks in human trabecular bone.

    Directory of Open Access Journals (Sweden)

    Aymeric Larrue

    Full Text Available Bone quality is an important concept to explain bone fragility in addition to bone mass. Among bone quality factors, microdamage which appears in daily life is thought to have a marked impact on bone strength and plays a major role in the repair process. The starting point for all studies designed to further our understanding of how bone microdamage initiate or dissipate energy, or to investigate the impact of age, gender or disease, remains reliable observation and measurement of microdamage. In this study, 3D Synchrotron Radiation (SR micro-CT at the micrometric scale was coupled to image analysis for the three-dimensional characterization of bone microdamage in human trabecular bone specimens taken from femoral heads. Specimens were imaged by 3D SR micro-CT with a voxel size of 1.4 µm. A new tailored 3D image analysis technique was developed to segment and quantify microcracks. Microcracks from human trabecular bone were observed in different tomographic sections as well as from 3D renderings. New 3D quantitative measurements on the microcrack density and morphology are reported on five specimens. The 3D microcrack density was found between 3.1 and 9.4/mm3 corresponding to a 2D density between 0.55 and 0.76 /mm2. The microcrack length and width measured in 3D on five selected microcrack ranged respectively from 164 µm to 209 µm and 100 µm to 120 µm. This is the first time that various microcracks in unloaded human trabecular bone--from the simplest linear crack to more complex cross-hatch cracks--have been examined and quantified by 3D imaging at this scale. The suspected complex morphology of microcracks is here considerably more evident than in the 2D observations. In conclusion, this technique opens new perspective for the 3D investigation of microcracks and the impact of age, disease or treatment.

  7. Decreased Bone Volume and Bone Mineral Density in the Tibial Trabecular Bone Is Associated with Per2 Gene by 405 nm Laser Stimulation

    Directory of Open Access Journals (Sweden)

    Yeong-Min Yoo

    2015-11-01

    Full Text Available Low-level laser therapy/treatment (LLLT using a minimally invasive laser needle system (MILNS might enhance bone formation and suppress bone resorption. In this study, the use of 405 nm LLLT led to decreases in bone volume and bone mineral density (BMD of tibial trabecular bone in wild-type (WT and Per2 knockout (KO mice. Bone volume and bone mineral density of tibial trabecular bone was decreased by 405 nm LLLT in Per2 KO compared to WT mice at two and four weeks. To determine the reduction in tibial bone, mRNA expressions of alkaline phosphatase (ALP and Per2 were investigated at four weeks after 405 nm laser stimulation using MILNS. ALP gene expression was significantly reduced in the LLLT-stimulated right tibial bone of WT and Per2 KO mice compared to the non-irradiated left tibia (p < 0.001. Per2 mRNA expression in WT mice was significantly reduced in the LLLT-stimulated right tibial bone compared to the non-irradiated left tibia (p < 0.001. To identify the decrease in tibial bone mediated by the Per2 gene, levels of runt-related transcription factor 2 (Runx2 and ALP mRNAs were determined in non-irradiated WT and Per2 KO mice. These results demonstrated significant downregulation of Runx2 and ALP mRNA levels in Per2 KO mice (p < 0.001. Therefore, the reduction in tibial trabecular bone resulting from 405 nm LLLT using MILNS might be associated with Per2 gene expression.

  8. Electron absorbed fractions of energy and S-values in an adult human skeleton based on {mu}CT images of trabecular bone

    Energy Technology Data Exchange (ETDEWEB)

    Kramer, R; Cassola, V F; Khoury, H J; De O Lira, C A B [Department of Nuclear Energy, Federal University of Pernambuco, Avenida Professor Luiz Freire, 1000, CEP 50740-540, Recife (Brazil); Richardson, R B [Radiation Protection Research and Instrumentation Branch, Atomic Energy of Canada Limited, Chalk River Laboratories, Chalk River, ON, K0J 1J0 (Canada); Vieira, J W [Federal Institute of Education, Science and Technology of Pernambuco, Recife (Brazil); Brown, K Robson, E-mail: rkramer@uol.com.br [Imaging Laboratory, Department of Archaeology and Anthropology, University of Bristol, Bristol (United Kingdom)

    2011-03-21

    When the human body is exposed to ionizing radiation, among the soft tissues at risk are the active marrow (AM) and the bone endosteum (BE) located in tiny, irregular cavities of trabecular bone. Determination of absorbed fractions (AFs) of energy or absorbed dose in the AM and the BE represent one of the major challenges of dosimetry. Recently, at the Department of Nuclear Energy at the Federal University of Pernambuco, a skeletal dosimetry method based on {mu}CT images of trabecular bone introduced into the spongiosa voxels of human phantoms has been developed and applied mainly to external exposure to photons. This study uses the same method to calculate AFs of energy and S-values (absorbed dose per unit activity) for electron-emitting radionuclides known to concentrate in skeletal tissues. The modelling of the skeletal tissue regions follows ICRP110, which defines the BE as a 50 {mu}m thick sub-region of marrow next to the bone surfaces. The paper presents mono-energetic AFs for the AM and the BE for eight different skeletal regions for electron source energies between 1 keV and 10 MeV. The S-values are given for the beta emitters {sup 14}C, {sup 59}Fe, {sup 131}I, {sup 89}Sr, {sup 32}P and {sup 90}Y. Comparisons with results from other investigations showed good agreement provided that differences between methodologies and trabecular bone volume fractions were properly taken into account. Additionally, a comparison was made between specific AFs of energy in the BE calculated for the actual 50 {mu}m endosteum and the previously recommended 10 {mu}m endosteum. The increase in endosteum thickness leads to a decrease of the endosteum absorbed dose by up to 3.7 fold when bone is the source region, while absorbed dose increases by {approx}20% when the beta emitters are in marrow.

  9. Chondrocyte-specific knockout of Cbfβ reveals the indispensable function of Cbfβ in chondrocyte maturation, growth plate development and trabecular bone formation in mice.

    Science.gov (United States)

    Wu, Mengrui; Li, Yi-Ping; Zhu, Guochun; Lu, Yun; Wang, Yiping; Jules, Joel; McConnell, Matthew; Serra, Rosa; Shao, Jian-Zhong; Chen, Wei

    2014-01-01

    Despite years of research into bone formation, the mechanisms by which transcription factors specify growth plate development and trabecular bone formation remain unclear and the role of hypertrophic chondrocytes in trabeculae morphogenesis is controversial. To study the role of Core binding factor beta (Cbfβ) in postnatal cartilage development and endochondral bone formation, we generated chondrocyte-specific Cbfβ-deficient mice (Cbfβf/fCol2α1-Cre mice) using floxed alleles of Cbfβ (Cbfβf/f) and Cre driven by the Collagen 2α1 promoter (Col2α1-Cre). Cbfβf/fCol2α1-Cre mice evaded developmental and newborn lethality to survive to adulthood and displayed severe skeletal malformation. Cbfβf/fCol2α1-Cre mice had dwarfism, hypoplastic skeletons, defective bone mineralization, shortened limbs, shortened sternum bodies, and un-calcified occipital bones and hyoid bones. In the long bone cartilage, the resting zone was elongated, and chondrocyte proliferation and hypertrophy were impaired in Cbfβf/fCol2α1-Cre mice, which led to deformation of the growth plates. Primary spongiosa formation was delayed, diaphysis was shortened and trabecular bone formation was almost absent in the mutant mice. In addition, lamellar bone formation in the secondary spongiosa was also impaired. However, osteoclast formation in the trabecular bone was not affected. Cbfβ deficiency led to down-regulation of chondrocyte-regulating genes [i.e, patched (Ptc1), Cyclin D1 and Indian hedgehog (Ihh)] in the cartilage. Interestingly, the expression of Runx2 and Runx3 was not changed in the cartilage of the mutants. Collectively, the results revealed that Cbfβ is crucial for postnatal skeletal development and endochondral bone formation through its function in growth plate development and chondrocyte proliferation and differentiation. This study also revealed that chondrocyte maturation, mediated by Cbfβ, was critical to trabecular bone morphogenesis. Significantly, these findings provide

  10. Industrial cultures

    DEFF Research Database (Denmark)

    Rasmussen, Lauge Baungaard

    1996-01-01

    The chapter deals with different paradigms andtheories of cultural development. The problem toexplain change and methods to analyse developmentin different cultures are presented and discussed.......The chapter deals with different paradigms andtheories of cultural development. The problem toexplain change and methods to analyse developmentin different cultures are presented and discussed....

  11. TBS (Trabecular Bone Score) Expands Understanding of Spaceflight Effects on the Lumbar Spine of Long Duration Astronauts

    Science.gov (United States)

    Sibonga, Jean D.; Smith, Scott A.; Hans, Didier; LeBlanc, Adrian; Spector, Elisabeth; Evans, Harlan; King, Lisa

    2014-01-01

    Background: Bone loss due to long-duration spaceflight has been characterized by both DXA and QCT serial scans. It is unclear if these spaceflight-induced changes in bone mineral density and structure result in increased fracture incidence. NASA astronauts currently fly on 5-6-month missions on the International Space Station (ISS) and at least one 12-month mission is planned. While NASA has measured areal BMD (by DXA) and volumetric BMD (by QCT), and has estimated hip strength (by finite element models of QCT data, no method has yet been used to examine bone microarchitecture from lumbar spine (LS). DXA scans are routinely performed pre- and post-flight on all ISS astronauts to follow BMD changes associated with space flight. Trabecular Bone Score (TBS) is a relatively new method that measures grey-scale-level texture information extracted from lumbar spine DXA images and correlates with 3D parameters of bone micro-architecture. We evaluated the ability of LS TBS to discriminate changes in astronauts who have flown on ISS missions and to determine if TBS can provide additional information compared to DXA. Methods: LS (L1-4) DXA scans from 51 astronauts (mean age, 47 +/- 4) were divided into 3 groups based on the exercise regimes performed while onboard the ISS. Pre-ARED (exercise using a load-limited resistive exercise device, <300lb), ARED (exercise with a high-load resistive exercise device, up to 600lb) and a Bisphos group (ARED exercise and a 70-mg alendronate tablet once a week before and during flight, starting 17 days before launch). DXA scans were performed and analyzed on a Hologic Discovery W using the same technician for the pre- and postflight scans. LSC for the LS in our laboratory is 0.025 g/cm2. TBS was performed at the Mercy Hospital, Cincinnati, Ohio on a similar Hologic computer. TBS precision was calculated from 16 comparable test subjects (0.0XX g/cm2). Data were preliminary analyzed using a paired, 2-tailed t-test for the difference between

  12. Does weight gain induce cortical and trabecular bone regain in anorexia nervosa? A two-year prospective study.

    Science.gov (United States)

    Milos, Gabriella; Spindler, Anja; Rüegsegger, Peter; Hasler, Gregor; Schnyder, Ulrich; Laib, Andres; Gallo, Luigi M; Uebelhart, Daniel; Häuselmann, Hansjörg

    2007-11-01

    This prospective study examines bone density and structure over a two-year time period in women with anorexia nervosa (AN) under weight gain treatment. Twenty-four women with AN were examined at baseline and at two annual follow-up examinations. In 9 AN patients BMI increased whereas in 15 it remained unchanged or decreased. Dual energy X-ray absorptiometry (DXA) was performed on the lumbar spine, the femoral neck and the whole hip and three-dimensional peripheral quantitative computer tomography (3D-pQCT) was performed on the ultradistal radius. ANOVAs for repeated measures were used to examine change over time in BMI and bone parameters. At baseline, patients with increased BMI had significantly higher bone density of femoral neck and total hip, and higher levels in all 3D-pQCT parameters of the ultradistal radius, compared to the group with unchanged or decreased BMI. The two groups did not differ at baseline in bone density of the spine. ANOVAs showed that bone density of the total hip increased significantly and that overall bone density (D100), the density of the trabecular area (D.Trab.) and the cortical thickness (C.Th.) in the ultradistal radius decreased significantly. Group x time interactions showed that changes over time were different in the two groups with regard to spine density and in the parameters D100, D.Trab. and C.Th. of the ultradistal radius. In the group with increased BMI the spine density dropped at the first follow-up whereas at the second follow-up it rose again to baseline. Patients with unchanged or decreased BMI showed a small but steady increase in spine density. The group changes of D100, D.Trab. and C.Th. of the ultradistal radius all followed the same pattern. Bone mineral density at all locations measured with both technologies (DXA and 3D-pQCT) did not vary according to BMI changes. The course of bone density and structure at different locations was different, and, despite weight increase, bone regain appeared to need different

  13. Trabecular metal cup without augments for acetabular revision in case of extensive bone loss and low bone-prosthesis contact.

    Science.gov (United States)

    Pierannunzii, L; Mambretti, A; D'Imporzano, M

    2011-01-01

    Current evidences in revision hip arthroplasty suggest to treat severe acetabular bone loss with dedicated implants, such as anti-protrusio cages, stemmed cups, modular systems supplied with iliac flanges and obturatory hook. However recent literature is reporting satisfactory outcomes with simple elliptical Trabecular Metal cups. Purpose of the study was to evaluate mid-term results of such a surgical procedure. All hip revisions performed from 2008 to 2009 with implantation of a TMT multi-hole acetabular cup without augmentations were retrospectively reviewed. The cases with low-degree acetabular bone loss (stage I and II according to GIR classification), with surgical report poorly describing the bone defect, with inadequate pre- and post-operative x-rays were ruled out. Twenty-five cases were identified, but four were lost to follow-up. The twenty-one patients were 71 year-old on average (from 60 to 82), with stage IV bone loss in 6 cases and stage III bone loss in 15 cases. Mean interval from surgery to evaluation was 20.9 months (from 13 to 30). The evaluation included bone-prosthesis contact estimation, component position, survivorship, complications, final Harris Hip Score, presence of periprosthetic radiolucencies. Host bone-prosthesis contact was estimated to be about 35%. Only three implant were subsequently reoperated (for infection, early migration, recurrent dislocation). The HHS among non-reoperated 18 patients was 81.96 on average (from 63.44 to 95.82). Six cases showed thin radiolucencies in one of the three Charnley zones, while three cases showed radiolucencies in two. None of these images was evolutive, thus they were not considered signs of loosening. The mid-term results of this series confirm the hypothesis that a porous tantalum acetabular cup is an effective option to deal with difficult acetabular revisions. Although no extra-acetabular fixation device is available, the very high surface friction guaranteed by the material and the

  14. Bone ingrowth potential of electron beam and selective laser melting produced trabecular-like implant surfaces with and without a biomimetic coating.

    Science.gov (United States)

    Biemond, J E; Hannink, G; Verdonschot, N; Buma, P

    2013-03-01

    The bone ingrowth potential of trabecular-like implant surfaces produced by either selective laser melting (SLM) or electron beam melting (EBM), with or without a biomimetic calciumphosphate coating, was examined in goats. For histological analysis and histomorphometry of bone ingrowth depth and bone implant contact specimens were implanted in the femoral condyle of goats. For mechanical push out tests to analyse mechanical implant fixation specimens were implanted in the iliac crest. The follow up periods were 4 (7 goats) and 15 weeks (7 goats). Both the SLM and EBM produced trabecular-like structures showed a variable bone ingrowth after 4 weeks. After 15 weeks good bone ingrowth was found in both implant types. Irrespective to the follow up period, and the presence of a coating, no histological differences in tissue reaction around SLM and EBM produced specimens was found. Histological no coating was detected at 4 and 15 weeks follow up. At both follow up periods the mechanical push out strength at the bone implant interface was significantly lower for the coated SLM specimens compared to the uncoated SLM specimens. The expected better ingrowth characteristics and mechanical fixation strength induced by the coating were not found. The lower mechanical strength of the coated specimens produced by SLM is a remarkable result, which might be influenced by the gross morphology of the specimens or the coating characteristics, indicating that further research is necessary.

  15. Helmholtz-pair transmit coil with integrated receive array for high-resolution MRI of trabecular bone in the distal tibia at 7 T

    Science.gov (United States)

    Wright, Alexander C.; Lemdiasov, Rostislav; Connick, Thomas J.; Bhagat, Yusuf A.; Magland, Jeremy F.; Song, Hee Kwon; Toddes, Steven P.; Ludwig, Reinhold; Wehrli, Felix W.

    2011-05-01

    A Helmholtz-pair local transmit RF coil with an integrated four-element receive array RF coil and foot immobilization platform was designed and constructed for imaging the distal tibia in a whole-body 7 T MRI scanner. Simulations and measurements of the B1 field distribution of the transmit coil are described, along with SAR considerations for operation at 7 T. Results of imaging the trabecular bone of three volunteers at 1.5 T, 3 T and 7 T are presented, using identical 1.5 T and 3 T versions of the 7 T four-element receive array. The spatially registered images reveal improved visibility for individual trabeculae and show average gains in SNR of 2.8× and 4.9× for imaging at 7 T compared to 3 T and 1.5 T, respectively. The results thus display an approximately linear dependence of SNR with field strength and enable the practical utility of 7 T scanners for micro-MRI of trabecular bone.

  16. The effect of Ginkgo biloba extract treatment in the Bcl-2 expression by osteoblasts in the femoral trabecular bone of Wistar rats with glucocorticoid-induced osteoporosis

    Directory of Open Access Journals (Sweden)

    Leda M.F. Lucinda

    2014-06-01

    Full Text Available Evaluate the effect of the extract of Ginkgo biloba L., Ginkgoaceae (EGb in the Bcl-2 expression by osteoblasts in the femoral trabecular bone of Wistar rats with glucocorticoid-induced osteoporosis. Rats were divided into five groups: osteoporosis; EGb1 (28 mg/kg; EGb2 (56 mg/kg; alendronate (0.2 mg/animal and control. The treatments were conducted for 20 or 30 days. The Bcl-2 expression by osteoblasts cells was evaluated in the femoral trabecular bone. The control group was compared with the osteoporosis-induced group (Student's t-test. The other groups were analyzed by ANOVA test followed by Tukey's test (p < 0.05. The percentage of Bcl-2 expression was reduced, when the control group (17.95 ± 3.45 20 days; 21.11 ± 3.43 30 days was compared with the osteoporosis group (10.64 ± 3.30 20 days; 9.72 ± 2.84 30 days. Nevertheless, this percentage increased in the EGb2 group (18.58 ± 3.41 20 days; 16.51 ± 1.80 30 days when compared to the osteoporosis group. The EGb increased the expression of the anti-apoptotic protein, suggesting a decrease in osteoblast apoptosis.

  17. Cultural psychology.

    Science.gov (United States)

    Heine, Steven J; Ruby, Matthew B

    2010-03-01

    Humans are a cultural species, constantly navigating a complex web of culturally bound practices, norms, and worldviews. This article provides a brief overview of the relatively young field of cultural psychology, which investigates the many ways psychology and culture interweave with one another. Highlighting the cultural nature of the human species, it draws upon research on cultural evolution, enculturation, and developmental processes. This review further summarizes a number of cultural differences in how people perceive the self, and the behavioral consequences that follow from these differences, in the domains of internal and external attribution styles, motivations for self-enhancement, approach/avoidance, primary and secondary control, as well as motivations for distinctiveness and conformity. Additionally, the review discusses research on the intersection of culture and emotion, as well as cultural differences in cognition, perception, and reasoning. Copyright © 2010 John Wiley & Sons, Ltd. For further resources related to this article, please visit the WIREs website. Copyright © 2010 John Wiley & Sons, Ltd.

  18. Cultural commons and cultural evolution

    OpenAIRE

    Giangiacomo Bravo

    2010-01-01

    Culture evolves following a process that is akin to biological evolution, although with some significant differences. At the same time culture has often a collective good value for human groups. This paper studies culture in an evolutionary perspective, with a focus on the implications of group definition for the coexistence of different cultures. A model of cultural evolution is presented where agents interacts in an artificial environment. The belonging to a specific memetic group is a majo...

  19. Efficacy of two trabecular micro-bypass stents combined with topical travoprost in open-angle glaucoma not controlled on two preoperative medications: 3-year follow-up

    Directory of Open Access Journals (Sweden)

    Chang DF

    2017-03-01

    Full Text Available David F Chang,1 Eric D Donnenfeld,2 L Jay Katz,3 Lilit Voskanyan,4 Iqbal Ike K Ahmed,5 Thomas W Samuelson,6 Jane Ellen Giamporcaro,7 Dana M Hornbeak,7 Kerry D Solomon8 1Altos Eye Physicians, Los Altos, CA, 2Ophthalmic Consultants of Long Island, Rockville Centre, NY, 3Department of Ophthalmology, Wills Eye Hospital, Jefferson Medical College, Philadelphia, PA, USA; 4S.V. Malayan Ophthalmology Centre, Yerevan, Armenia; 5Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, ON, Canada; 6Minnesota Eye Consultants, Minneapolis, MN, 7Glaukos Corporation, San Clemente, CA, 8Carolina Eyecare Physicians, Mount Pleasant, SC, USA Purpose: To evaluate the long-term intraocular pressure (IOP-lowering effect and safety parameters following treatment with two trabecular micro-bypass stents and topical prostaglandin in phakic eyes with open-angle glaucoma (OAG not controlled on two preoperative medications. Methods: This prospective, single-arm, unmasked study enrolled 39 qualified phakic eyes with OAG not controlled on 2 medications, preoperative medicated IOP of 18–30 mmHg, and IOP following medication washout of 22–38 mmHg. Two trabecular micro-bypass stents were implanted as a standalone procedure, and travoprost was started on postoperative day 1. Evaluations included IOP, best-corrected visual acuity, medication use, fundus and slit-lamp examinations, visual field, cup:disc ratio, central corneal thickness, and ocular complications. Data through 18 months were summarized previously. Thirty-seven of the original 39 subjects have been followed for 3 years postoperatively; follow-up is continuing for 5 years. Results: At 3 years postoperative, 97% of eyes had achieved an IOP reduction of ≥20% from baseline with a reduction of 1 medication. Eighty-six percent of eyes had IOP of ≤18 mmHg with a reduction of 1 medication. Mean medicated IOP decreased to 14.0±2.6 mmHg on 1 medication versus 22.4±2.3 mmHg on 2 medications

  20. Repellent Culture.

    Science.gov (United States)

    Carroll, Jeffrey

    2001-01-01

    Considers defining "culture," noting how it is difficult to define because those individuals defining it cannot separate themselves from it. Relates these issues to student writing and their writing improvement. Addresses violence in relation to culture. (SG)

  1. Culturing Protozoa.

    Science.gov (United States)

    Stevenson, Paul

    1980-01-01

    Compares various nutrient media, growth conditions, and stock solutions used in culturing protozoa. A hay infusion in Chalkey's solution maintained at a stable temperature is recommended for producing the most dense and diverse cultures. (WB)

  2. Throat Culture

    Science.gov (United States)

    ... products and services. Advertising & Sponsorship: Policy | Opportunities Throat Culture Share this page: Was this page helpful? Collecting | ... treatment | Getting results | see BLOOD SAMPLE Collecting A culture is a test that is often used to ...

  3. Culturing Protozoa.

    Science.gov (United States)

    Stevenson, Paul

    1980-01-01

    Compares various nutrient media, growth conditions, and stock solutions used in culturing protozoa. A hay infusion in Chalkey's solution maintained at a stable temperature is recommended for producing the most dense and diverse cultures. (WB)

  4. Safety culture

    Energy Technology Data Exchange (ETDEWEB)

    Keen, L.J. [Canadian Nuclear Safety Commission, Ottawa, Ontario (Canada)

    2003-07-01

    Safety culture has become a topic of increasing interest for industry and regulators as issues are raised on safety problems around the world. The keys to safety culture are organizational effectiveness, effective communications, organizational learning, and a culture that encourages the identification and resolution of safety issues. The necessity of a strong safety culture places an onus on all of us to continually question whether the safety measures already in place are sufficient, and are being applied. (author)

  5. Cultural clashes

    National Research Council Canada - National Science Library

    2001-01-01

    ... is essentially a cultural, not religious, practice. Siddiq Bazarwala Singapore From Georgina Dubourcq Sir: While I don't disagree with Dr Dalrymple's comments about the way Muslim culture can treat women, I wonder how a culture which condones lap-dancing, pornographic videos and often turns a blind eye to under-age prostitution can really feel superior. I...

  6. Handling Culture

    NARCIS (Netherlands)

    Pieter van Nispen tot Pannerden

    2011-01-01

    The article indicates how companies may prepare for and deal with cultural differences. Because the research base is still rather limited an overall perspective may not be realised. After discussing definitions and concepts of culture, as well as values, cultural differences between states are discu

  7. Handling Culture

    NARCIS (Netherlands)

    Nispen tot Pannerden, P.J.M. van

    2011-01-01

    The article indicates how companies may prepare for and deal with cultural differences. Because the research base is still rather limited an overall perspective may not be realised. After discussing definitions and concepts of culture, as well as values, cultural differences between states are discu

  8. Beyond Culture.

    Science.gov (United States)

    Barron, Daniel D.

    1993-01-01

    Discusses the lack of literature relating to cultural differences and school library media programs and reviews the book "Beyond Culture" by Edward T. Hall. Highlights include the population/environment crisis, cultural literacy, the use of technology, and Marshall McLuhan's idea of the global village. (LRW)

  9. Cultural Rights and Cultural Diversity

    Institute of Scientific and Technical Information of China (English)

    WANG SIXIN

    2011-01-01

    @@ Culture is a very big concept, big enough almost to comprise all the activities of human beings and the tangible and intangible results caused by human activities.Therefore, it is very difficult to define culture in a few words.

  10. Mechanically loaded ex vivo bone culture system 'Zetos': Systems and culture preparation

    Directory of Open Access Journals (Sweden)

    C M Davies

    2006-04-01

    Full Text Available This paper introduces the culture preparation of ovine, bovine and human cancellous bone cores to be used in an explants model Zetos. The three dimensional (3D bone cores were prepared and evaluated for all three animals. Bone cells in vivo constantly interact with each other, migratory cells, surrounding extracellular matrix (ECM and interstitial fluid in a microenvironment, which continuously responds to various endogenous and exogenous stimuli. The Zetos system was designed to culture and mechanically load viable cancellous bone explants in their near natural microenvironment. This 3D ex vivo system bridges the current gap between in vitro and in vivo methods. One aim of this work was to compare the macro and micro-architecture of ovine, bovine and human cancellous bone tissue in preparation for culture within the Zetos system in order to determine the optimal source of experimental material. A second aim was to optimise the preparations of the bone cores as well as develop techniques involved during tissue maintenance. Bone core response was visualised using histological and immunohistochemical methods. The results demonstrate that cancellous bone explants vary greatly in trabecular density and bone volume depending on species, age and location. Sheep and human samples displayed the greatest variation between bones cores when compared to bovine. Even cores taken from the same animal possessed very different characteristics. The histology demonstrated normal bone and cell structure after the core preparation. Immunohistochemistry results demonstrated antigen retention after preparation methods.

  11. 3D porous architecture of stacks of β-TCP granules compared with that of trabecular bone: a microCT, vector analysis and compression study

    Directory of Open Access Journals (Sweden)

    Daniel eCHAPPARD

    2015-10-01

    Full Text Available The 3D arrangement of porous granular biomaterials usable to fill bone defects has received little study. Granular biomaterials occupy 3D space when packed together in a manner that creates a porosity suitable for the invasion of vascular and bone cells. Granules of β-TCP were prepared with either 12.5 or 25g of β-TCP powder in the same volume of slurry. When the granules were placed in a test tube, this produced 3D stacks with a high (HP or low porosity (LP, respectively. Stacks of granules mimic the filling of a bone defect by a surgeon. The aim of this study was to compare the porosity of stacks of β-TCP granules with that of cores of trabecular bone. Biomechanical compression tests were done on the granules stacks. Bone cylinders were prepared from calf tibia plateau, constituted high density (HD blocks. Low density (LD blocks were harvested from aged cadaver tibias. Microcomputed tomography was used on the β-TCP granule stacks and the trabecular bone cores to determine porosity and specific surface. A vector projection algorithm was used to image porosity employing a frontal plane image which was constructed line by line from all images of a microCT stack. Stacks of HP granules had porosity (75.3 ± 0.4% and fractal lacunarity (0.043 ± 0.007 intermediate between that of HD (resp. 69.1 ± 6.4%, p<0.05 and 0.087 ± 0.045, p<0.05 and LD bones (resp. 88.8 ± 1.57% and 0.037 ± 0.014 but exhibited a higher surface density (5.56 ± 0.11 mm2/mm3 vs. 2.06 ± 0.26 for LD, p<0.05. LP granular arrangements created large pores coexisting with dense areas of material. Frontal plane analysis evidenced a more regular arrangement of β-TCP granules than bone trabeculae. Stacks of HP granules represent a scaffold that resembles trabecular bone in its porous microarchitecture.

  12. 3D Porous Architecture of Stacks of β-TCP Granules Compared with That of Trabecular Bone: A microCT, Vector Analysis, and Compression Study

    Science.gov (United States)

    Chappard, Daniel; Terranova, Lisa; Mallet, Romain; Mercier, Philippe

    2015-01-01

    The 3D arrangement of porous granular biomaterials usable to fill bone defects has received little study. Granular biomaterials occupy 3D space when packed together in a manner that creates a porosity suitable for the invasion of vascular and bone cells. Granules of beta-tricalcium phosphate (β-TCP) were prepared with either 12.5 or 25 g of β-TCP powder in the same volume of slurry. When the granules were placed in a test tube, this produced 3D stacks with a high (HP) or low porosity (LP), respectively. Stacks of granules mimic the filling of a bone defect by a surgeon. The aim of this study was to compare the porosity of stacks of β-TCP granules with that of cores of trabecular bone. Biomechanical compression tests were done on the granules stacks. Bone cylinders were prepared from calf tibia plateau, constituted high-density (HD) blocks. Low-density (LD) blocks were harvested from aged cadaver tibias. Microcomputed tomography was used on the β-TCP granule stacks and the trabecular bone cores to determine porosity and specific surface. A vector-projection algorithm was used to image porosity employing a frontal plane image, which was constructed line by line from all images of a microCT stack. Stacks of HP granules had porosity (75.3 ± 0.4%) and fractal lacunarity (0.043 ± 0.007) intermediate between that of HD (respectively 69.1 ± 6.4%, p < 0.05 and 0.087 ± 0.045, p < 0.05) and LD bones (respectively 88.8 ± 1.57% and 0.037 ± 0.014), but exhibited a higher surface density (5.56 ± 0.11 mm2/mm3 vs. 2.06 ± 0.26 for LD, p < 0.05). LP granular arrangements created large pores coexisting with dense areas of material. Frontal plane analysis evidenced a more regular arrangement of β-TCP granules than bone trabecule. Stacks of HP granules represent a scaffold that resembles trabecular bone in its porous microarchitecture. PMID:26528240

  13. Culture evolves.

    Science.gov (United States)

    Whiten, Andrew; Hinde, Robert A; Laland, Kevin N; Stringer, Christopher B

    2011-04-12

    Culture pervades human lives and has allowed our species to create niches all around the world and its oceans, in ways quite unlike any other primate. Indeed, our cultural nature appears so distinctive that it is often thought to separate humanity from the rest of nature and the Darwinian forces that shape it. A contrary view arises through the recent discoveries of a diverse range of disciplines, here brought together to illustrate the scope of a burgeoning field of cultural evolution and to facilitate cross-disciplinary fertilization. Each approach emphasizes important linkages between culture and evolutionary biology rather than quarantining one from the other. Recent studies reveal that processes important in cultural transmission are more widespread and significant across the animal kingdom than earlier recognized, with important implications for evolutionary theory. Recent archaeological discoveries have pushed back the origins of human culture to much more ancient times than traditionally thought. These developments suggest previously unidentified continuities between animal and human culture. A third new array of discoveries concerns the later diversification of human cultures, where the operations of Darwinian-like processes are identified, in part, through scientific methods borrowed from biology. Finally, surprising discoveries have been made about the imprint of cultural evolution in the predispositions of human minds for cultural transmission.

  14. Copas de metal trabecular y aloinjertos óseos impactados en defectos acetabulares graves. Resultados a los 2-4 años. [Impacted bone allografts and trabecular metal cups in severe acetabular bone defects: 2 to 4-year results.

    Directory of Open Access Journals (Sweden)

    Martín Buttaro

    2014-06-01

    Full Text Available In­tro­duc­ción: El objetivo principal es presentar la supervivencia del componente acetabular en pacientes con defectos graves reconstruidos con copas de metal trabecular combinadas con aloinjertos óseos impactados. Como objetivo secundario, se compararon estos resultados con los previamente obtenidos por los autores en defectos de similar gravedad utilizando anillos de reconstrucción y aloinjertos óseos. Materiales­ y­ Métodos:­ Se realizaron 20 cirugías de revisión en 19 pacientes (edad promedio 65 años, controlados, de forma prospectiva, con defectos acetabulares graves tipos 3A o 3B de Paprosky, por falla mecánica o infecciosa. El puntaje funcional promedio preoperatorio fue de 6,2 puntos, según la escala de Merle D ́Aubigne. Siempre se utilizaron copas de metal trabecular y aloinjertos óseos impactados. Resultados:­ A los 30 meses de seguimiento promedio (rango 24-48 meses, la supervivencia del componente acetabular fue del 95% (IC = 75%-98%. Un paciente presentó un aflojamiento acetabular por infección profunda a las 16 semanas de la revisión y fue tratado con una artroplastia de resección. El puntaje funcional promedio, excluido el caso con aflojamiento posoperatorio, fue de 16,2 puntos. Se observó la incorporación de los aloinjertos óseos en todos los pacientes, salvo el caso con infección profunda. La comparación con nuestras series históricas reconstruidas con anillos de Kerboull o con anillos GAP arrojó resultados altamente favorables a favor de las copas de metal trabecular.  Conclusiones: Las copas de metal trabecular asociadas a aloinjertos óseos impactados ofrecen una alternativa válida en cirugía de revisión acetabular con defectos graves del capital óseo. Este método se asocia a resultados más favorables que los obtenidos antes con anillos de reconstrucción.

  15. Prevalence of Vertebral Compression Fractures on Routine CT Scans According to L1 Trabecular Attenuation: Determining Relevant Thresholds for Opportunistic Osteoporosis Screening.

    Science.gov (United States)

    Graffy, Peter M; Lee, Scott J; Ziemlewicz, Timothy J; Pickhardt, Perry J

    2017-09-01

    Radiologists interpreting body CT scans may be the first to identify osteoporosis and associated vertebral fractures. This study correlates L1 trabecular attenuation measurements with prevalent vertebral body fractures in older adults undergoing routine CT. Mean L1 trabecular attenuation was measured at thoracoabdominal CT in 1966 consecutive adults (983 men and 983 women) 65 years and older (mean age, 74.1 ± 6.6 [SD] years). Sagittal reconstructions and lateral scouts were analyzed for moderate or severe thoracolumbar vertebral compression fractures according to the Genant semiquantitative assessment method. The diagnostic performance of L1 attenuation for the evaluation of prevalent vertebral fractures was assessed, including ROC curve analysis. A total of 162 (8.2%) individuals (mean age, 78.3 years; 66 men, 96 women) had at least one moderate or severe vertebral fracture. The mean L1 attenuation was 70.2 HU among patients with a prevalent fracture, whereas it was 132.3 HU among patients without fracture (p < 0.001). The prevalence of moderate or severe vertebral compression fractures was 32.5% when L1 attenuation was ≤ 90 HU. Prevalence increased to 49.2% with L1 attenuation of ≤ 50 HU. ROC curve analysis determined an optimal threshold of 90 HU (sensitivity = 86.9%, specificity = 83.9%), with a corresponding AUC of 0.895. The odds ratio of having a moderate or severe vertebral compression fracture was 31.9 for L1 attenuation ≤ 90 HU (95% CI, 20.2-50.5; p < 0.001). Patients with moderate or severe vertebral compression fractures have significantly lower L1 attenuation values than patients who do not. L1 attenuation ≤ 90 HU may represent an optimal threshold for determining risk for osteoporotic vertebral fractures.

  16. 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.

  17. Aging Versus Postmenopausal Osteoporosis: Bone Composition and Maturation Kinetics at Actively-Forming Trabecular Surfaces of Female Subjects Aged 1 to 84 Years.

    Science.gov (United States)

    Paschalis, Eleftherios P; Fratzl, Peter; Gamsjaeger, Sonja; Hassler, Norbert; Brozek, Wolfgang; Eriksen, Erik F; Rauch, Frank; Glorieux, Francis H; Shane, Elizabeth; Dempster, David; Cohen, Adi; Recker, Robert; Klaushofer, Klaus

    2016-02-01

    Bone strength depends on the amount of bone, typically expressed as bone mineral density (BMD), determined by dual-energy X-ray absorptiometry (DXA), and on bone quality. Bone quality is a multifactorial entity including bone structural and material compositional properties. The purpose of the present study was to examine whether bone material composition properties at actively-forming trabecular bone surfaces in health are dependent on subject age, and to contrast them with postmenopausal osteoporosis patients. To achieve this, we analyzed by Raman microspectroscopy iliac crest biopsy samples from healthy subjects aged 1.5 to 45.7 years, paired biopsy samples from females before and immediately after menopause aged 46.7 to 53.6 years, and biopsy samples from placebo-treated postmenopausal osteoporotic patients aged 66 to 84 years. The monitored parameters were as follows: the mineral/matrix ratio; the mineral maturity/crystallinity (MMC); nanoporosity; the glycosaminoglycan (GAG) content; the lipid content; and the pyridinoline (Pyd) content. The results indicate that these bone quality parameters in healthy, actively-forming trabecular bone surfaces are dependent on subject age at constant tissue age, suggesting that with advancing age the kinetics of maturation (either accumulation, or posttranslational modifications, or both) change. For most parameters, the extrapolation of models fitted to the individual age dependence of bone in healthy individuals was in rough agreement with their values in postmenopausal osteoporotic patients, except for MMC, lipid, and Pyd content. Among these three, Pyd content showed the greatest deviation between healthy aging and disease, highlighting its potential to be used as a discriminating factor.

  18. Short-term and long-term site-specific effects of tennis playing on trabecular and cortical bone at the distal radius.

    Science.gov (United States)

    Ducher, Gaële; Tournaire, Nicolas; Meddahi-Pellé, Anne; Benhamou, Claude-Laurent; Courteix, Daniel

    2006-01-01

    Mechanical loading during growth magnifies the normal increase in bone diameter occurring in long bone shafts, but the response to loading in long bone ends remains unclear. The aim of the study was to investigate the effects of tennis playing during growth at the distal radius, comparing the bone response at trabecular and cortical skeletal sites. The influence of training duration was examined by studying bone response in short-term (children) and long-term (young adults) perspectives. Bone area, bone mineral content (BMC), and bone mineral density (BMD) of the radius were measured by DXA in 28 young (11.6 +/- 1.4 years old) and 47 adult tennis players (22.3 +/- 2.7 years old), and 70 age-matched controls (12 children, 58 adults) at three sites: the ultradistal region (trabecular), the mid-distal region, and the third-distal region (cortical). At the ultradistal radius, young and adult tennis players displayed similar side-to-side differences, the asymmetry in BMC reaching 16.3% and 13.8%, respectively (P < 0.0001). At the mid- and third-distal radius, the asymmetry was much greater in adults than in children (P < 0.0001) for all the bone parameters (mid-distal radius, +6.6% versus +15.6%; third-distal radius, +6.9% versus +13.3%, for BMC). Epiphyseal bone enduring longitudinal growth showed a great capacity to respond to mechanical loading in children. Prolonging tennis playing into adulthood was associated with further increase in bone mineralization at diaphyseal skeletal sites. These findings illustrate the benefits of practicing impact-loading sports during growth and maintaining physical activity into adulthood to enhance bone mass accrual and prevent fractures later in life.

  19. Joint unloading implant modifies subchondral bone trabecular structure in medial knee osteoarthritis: 2-year outcomes of a pilot study using fractal signature analysis

    Directory of Open Access Journals (Sweden)

    Miller LE

    2015-01-01

    Full Text Available Larry E Miller,1,2 Miki Sode,3 Thomas Fuerst,3 Jon E Block2 1Miller Scientific Consulting, Inc., Asheville, NC, USA; 2The Jon Block Group, San Francisco, CA, USA; 3Bioclinica, Newark, CA, USA Background: Knee osteoarthritis (OA is largely attributable to chronic excessive and aberrant joint loading. The purpose of this pilot study was to quantify radiographic changes in subchondral bone after treatment with a minimally invasive joint unloading implant (KineSpring® Knee Implant System.Methods: Nine patients with unilateral medial knee OA resistant to nonsurgical therapy were treated with the KineSpring System and followed for 2 years. Main outcomes included Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC pain, function, and stiffness subscores and independent core laboratory determinations of joint space width and fractal signature of the tibial cortex.Results: WOMAC scores, on average, improved by 92% for pain, 91% for function, and 79% for stiffness over the 2-year follow-up period. Joint space width in the medial compartment of the treated knee significantly increased from 0.9 mm at baseline to 3.1 mm at 2 years; joint space width in the medial compartment of the untreated knee was unchanged. Fractal signatures of the vertically oriented trabeculae in the medial compartment decreased by 2.8% in the treated knee and increased by 2.1% in the untreated knee over 2 years. No statistically significant fractal signature changes were observed in the horizontally oriented trabeculae in the medial compartment or in the horizontal or vertical trabeculae of the lateral compartment in the treated knee.Conclusion: Preliminary evidence suggests that the KineSpring System may modify knee OA disease progression by increasing joint space width and improving subchondral bone trabecular integrity, thereby reducing pain and improving joint function. Keywords: disease modification, KineSpring, joint space, pain, trabecular

  20. Optimizing finite element predictions of local subchondral bone structural stiffness using neural network-derived density-modulus relationships for proximal tibial subchondral cortical and trabecular bone.

    Science.gov (United States)

    Nazemi, S Majid; Amini, Morteza; Kontulainen, Saija A; Milner, Jaques S; Holdsworth, David W; Masri, Bassam A; Wilson, David R; Johnston, James D

    2017-01-01

    Quantitative computed tomography based subject-specific finite element modeling has potential to clarify the role of subchondral bone alterations in knee osteoarthritis initiation, progression, and pain. However, it is unclear what density-modulus equation(s) should be applied with subchondral cortical and subchondral trabecular bone when constructing finite element models of the tibia. Using a novel approach applying neural networks, optimization, and back-calculation against in situ experimental testing results, the objective of this study was to identify subchondral-specific equations that optimized finite element predictions of local structural stiffness at the proximal tibial subchondral surface. Thirteen proximal tibial compartments were imaged via quantitative computed tomography. Imaged bone mineral density was converted to elastic moduli using multiple density-modulus equations (93 total variations) then mapped to corresponding finite element models. For each variation, root mean squared error was calculated between finite element prediction and in situ measured stiffness at 47 indentation sites. Resulting errors were used to train an artificial neural network, which provided an unlimited number of model variations, with corresponding error, for predicting stiffness at the subchondral bone surface. Nelder-Mead optimization was used to identify optimum density-modulus equations for predicting stiffness. Finite element modeling predicted 81% of experimental stiffness variance (with 10.5% error) using optimized equations for subchondral cortical and trabecular bone differentiated with a 0.5g/cm(3) density. In comparison with published density-modulus relationships, optimized equations offered improved predictions of local subchondral structural stiffness. Further research is needed with anisotropy inclusion, a smaller voxel size and de-blurring algorithms to improve predictions. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Spatial Culture

    DEFF Research Database (Denmark)

    2012-01-01

    – 2006. The essays published here allow us to subdivide the field of spatial culture into five major domains, summarized in the titles of chapters in the book: ”Perception and Strategies: Architecture”, ”Politics and Poetics: Urban Spaces”, ”Movements and Cityscape: Textuality”, ”Crisis and Construction......Spatial Culture – A Humanities Perspective Abstract of introductory essay by Henrik Reeh Secured by alliances between socio-political development and cultural practices, a new field of humanistic studies in spatial culture has developed since the 1990s. To focus on links between urban culture...... and modern society is, however, an intellectual practice which has a much longer history. Already in the 1980s, the debate on the modern and the postmodern cited Paris and Los Angeles as spatio-cultural illustrations of these major philosophical concepts. Earlier, in the history of critical studies, the work...

  2. Culture Shock

    Institute of Scientific and Technical Information of China (English)

    宋文玲

    2004-01-01

    Specialists say that it is not easy to get used to life in a new culture.“Culture shock”is the term these specialists use when talking about the feelings that people have in a new environment.There are three stages of culture shock,say the specialists.In the first stage,the newcomers like their new environment,Then when the fresh experience

  3. Cultural diversity

    OpenAIRE

    Raghavan, Raghu

    2011-01-01

    The concept of cultural diversity has emerged as an influential one having impact on multiple policy and legal instruments especially following the adoption of the UNESCO Convention on the Protection and Promotion of the Diversity of Cultural Expressions in 2005. The discussions on its appropriate implementation are however profoundly fragmented and often laden with political considerations. The present brief paper offers some thoughts on the meaning of cultural diversity and its implementati...

  4. Life under pressure: The role of ocular cribriform cells in preventing glaucoma.

    Science.gov (United States)

    Paula, Jayter S; O'Brien, Colm; Stamer, W Daniel

    2016-10-01

    Primary open-angle glaucoma is a multifactorial blinding disease often impacting the two pressure-sensitive regions of the eye: the conventional outflow pathway and the optic nerve head (ONH). The connective tissues that span these two openings in the globe are the trabecular meshwork of the conventional outflow pathway and the lamina cribrosa of the ONH. Resident cribiform cells of these two regions are responsible for actively remodeling and maintaining their connective tissues. In glaucoma, aberrant maintenance of the juxtacanalicular tissues (JCT) of the conventional outflow pathway results in ocular hypertension and pathological remodeling of the lamina cribrosa results in ONH cupping, damaging retinal ganglion cell axons. Interestingly, cells cultured from the lamina cribrosa and the JCT of the trabecular meshwork have similarities regarding gene expression, protein production, plus cellular responses to growth factors and mechanical stimuli. This review compares and contrasts the current knowledge of these two cell types, whose health is critical for protecting the eye from glaucomatous changes. In response to pressure gradients across their respective cribiform tissues, the goal is to better understand and differentiate healthy from pathological behavior of these two cell types.

  5. Skin or nail culture

    Science.gov (United States)

    Mucosal culture; Culture - skin; Culture - mucosal; Nail culture; Culture - fingernail; Fingernail culture ... There, it is placed in a special dish (culture). It is then watched to see if bacteria, ...

  6. Cultural probes

    DEFF Research Database (Denmark)

    Madsen, Jacob Østergaard

    2016-01-01

    The aim of this study was thus to explore cultural probes (Gaver, Boucher et al. 2004), as a possible methodical approach, supporting knowledge production on situated and contextual aspects of occupation.......The aim of this study was thus to explore cultural probes (Gaver, Boucher et al. 2004), as a possible methodical approach, supporting knowledge production on situated and contextual aspects of occupation....

  7. Manuscript Cultures

    DEFF Research Database (Denmark)

    What do Mesoamerica, Greece, Byzantium, Island, Chad, Ethiopia, India, Tibet, China and Japan have in common? Like many other cultures of the world, they share a particular form of cultural heritage: ancient handwritten documents. In 2007, scholars from some20 countries around the world gathered...

  8. Culture Stories

    DEFF Research Database (Denmark)

    Jensen, Ole B.

    2007-01-01

    by certain representations and embedded in certain norms and values. The analytical framework is applied on a case of cultural urban branding. The case is the harbour front in Aalborg, Denmark where a number of flagship architecture projects and cultural institutions are being planned. It is shown how...

  9. Cultural Communications.

    Science.gov (United States)

    Armas, Jose

    It is too often taken for granted that the communication process with culturally different children takes place as readily as it might with children from Anglo cultures. Most teachers receive training in verbal and formal communication skills; children come to school with nonverbal and informal communication skills. This initially can create…

  10. CULTURAL TOURISM

    Directory of Open Access Journals (Sweden)

    Dana POP

    2016-07-01

    Full Text Available In this paper we will try to analyse the cultural tourism. We will start by referring to the complex concepts of tourism and culture and to the synergies existing between them. We will define cultural tourism and present its appearance and evolution as well as its importance as a modern form of tourism. We will present the various types of cultural tourism with their characteristics and the specific features of cultural tourists according to their interests. We will also mention that there are advantages and disadvantages for any kind of tourism depending on the position – local communities, companies or tourists. For the future we will refer to the new partnership between UNWTO and UNESCO.

  11. Microstructural parameters of bone evaluated using HR-pQCT correlate with the DXA-derived cortical index and the trabecular bone score in a cohort of randomly selected premenopausal women.

    Directory of Open Access Journals (Sweden)

    Albrecht W Popp

    Full Text Available BACKGROUND: Areal bone mineral density is predictive for fracture risk. Microstructural bone parameters evaluated at the appendicular skeleton by high-resolution peripheral quantitative computed tomography (HR-pQCT display differences between healthy patients and fracture patients. With the simple geometry of the cortex at the distal tibial diaphysis, a cortical index of the tibia combining material and mechanical properties correlated highly with bone strength ex vivo. The trabecular bone score derived from the scan of the lumbar spine by dual-energy X-ray absorptiometry (DXA correlated ex vivo with the micro architectural parameters. It is unknown if these microstructural correlations could be made in healthy premenopausal women. METHODS: Randomly selected women between 20-40 years of age were examined by DXA and HR-pQCT at the standard regions of interest and at customized sub regions to focus on cortical and trabecular parameters of strength separately. For cortical strength, at the distal tibia the volumetric cortical index was calculated directly from HR-pQCT and the areal cortical index was derived from the DXA scan using a Canny threshold-based tool. For trabecular strength, the trabecular bone score was calculated based on the DXA scan of the lumbar spine and was compared with the corresponding parameters derived from the HR-pQCT measurements at radius and tibia. RESULTS: Seventy-two healthy women were included (average age 33.8 years, average BMI 23.2 kg/m(2. The areal cortical index correlated highly with the volumetric cortical index at the distal tibia (R  =  0.798. The trabecular bone score correlated moderately with the microstructural parameters of the trabecular bone. CONCLUSION: This study in randomly selected premenopausal women demonstrated that microstructural parameters of the bone evaluated by HR-pQCT correlated with the DXA derived parameters of skeletal regions containing predominantly cortical or cancellous bone

  12. Microstructural Parameters of Bone Evaluated Using HR-pQCT Correlate with the DXA-Derived Cortical Index and the Trabecular Bone Score in a Cohort of Randomly Selected Premenopausal Women

    Science.gov (United States)

    Popp, Albrecht W.; Buffat, Helene; Eberli, Ursula; Lippuner, Kurt; Ernst, Manuela; Richards, R. Geoff; Stadelmann, Vincent A.; Windolf, Markus

    2014-01-01

    Background Areal bone mineral density is predictive for fracture risk. Microstructural bone parameters evaluated at the appendicular skeleton by high-resolution peripheral quantitative computed tomography (HR-pQCT) display differences between healthy patients and fracture patients. With the simple geometry of the cortex at the distal tibial diaphysis, a cortical index of the tibia combining material and mechanical properties correlated highly with bone strength ex vivo. The trabecular bone score derived from the scan of the lumbar spine by dual-energy X-ray absorptiometry (DXA) correlated ex vivo with the micro architectural parameters. It is unknown if these microstructural correlations could be made in healthy premenopausal women. Methods Randomly selected women between 20–40 years of age were examined by DXA and HR-pQCT at the standard regions of interest and at customized sub regions to focus on cortical and trabecular parameters of strength separately. For cortical strength, at the distal tibia the volumetric cortical index was calculated directly from HR-pQCT and the areal cortical index was derived from the DXA scan using a Canny threshold-based tool. For trabecular strength, the trabecular bone score was calculated based on the DXA scan of the lumbar spine and was compared with the corresponding parameters derived from the HR-pQCT measurements at radius and tibia. Results Seventy-two healthy women were included (average age 33.8 years, average BMI 23.2 kg/m2). The areal cortical index correlated highly with the volumetric cortical index at the distal tibia (R  =  0.798). The trabecular bone score correlated moderately with the microstructural parameters of the trabecular bone. Conclusion This study in randomly selected premenopausal women demonstrated that microstructural parameters of the bone evaluated by HR-pQCT correlated with the DXA derived parameters of skeletal regions containing predominantly cortical or cancellous bone. Whether these indexes

  13. Trabecular bone mineral density measured by quantitative CT of the lumbar spine in children and adolescents: reference values and peak bone mass; Trabekulaere Knochendichte der Lendenwirbelsaeule bei Kindern und Jugendlichen in der quantitativen CT: Referenzwerte und Peak Bone Mass

    Energy Technology Data Exchange (ETDEWEB)

    Berthold, L.D.; Alzen, G. [Kinderradiologie, Zentrum fuer Radiologie, Universitaetsklinikum Giessen und Marburg GmbH, Standort Giessen (Germany); Haras, G. [Siemens AG, Medical Solutions, Forchheim (Germany); Mann, M. [AG Medizinische Statistik, Universitaetsklinikum Giessen und Marburg GmbH, Standort Giessen (Germany)

    2006-12-15

    Purpose: The aim of this study was to assess bone density values in the trabecular substance of the lumbar vertebral column in children and young adults in Germany from infancy to the age of peak bone mass. Materials and Methods: We performed quantiative computed tomography (QCT) on the first lumbar vertebra in 28 children and adolescents without diseases that may influence bone metabolism (15 boys, 13 girls, mean ages 11 and 8 years, respectively). We also measured 17 healthy young adults (9 men, 8 women, mean ages 20 and 21 years). We used a Somatom Balance Scanner (Siemens, Erlangen) and the Siemens Osteo software. Scan parameters: Slice thickness 1 cm, 80 kV, 81 or 114 mAs. We measured the trabecular bone density and the area and height of the vertebra and calculated the volume and content of calcium hydroxyapatite (Ca-HA) in the trabecular substance of the first lumbar vertebra. Results: Prepubertal boys had a mean bone density of 148.5 (median [med] 150.1, standard deviation [SD] 15.4) mg/Ca-HA per ml bone, and prepubertal girls had a mean density of 149.5 (med 150.8, SD 23.5) mg/ml. We did not observe a difference between prepubertal boys and girls. After puberty there was a significant difference (p<0.001) between males and females: Mean density (male) 158.0, med 162.5, SD 24.0 mg/ml, mean density (female) 191.2, med 191.3, SD 17.7 mg/ml. The Ca-HA content in the trabecular bone of the first lumbar vertebra was 1.1 (med 1.1, SD 0.5) g for prepubertal boys and 1.1 (0.9, 0.4) g for prepubertal girls. For post-pubertal males, the mean Ca-HA content was 3.5 g, med 3.5 SD 0.5 g, and for post-pubertal females, the mean content was 2.8, med 2.7, SD 0.4 g. Conclusion: The normal trabecular bone mineral density is 150 mg/ml with a standard deviation of 20 mg/ml independent of age or gender until the beginning of puberty. Peak bone mass (bone mineral content) in the trabecular substance of the lumbar vertebral column is higher in males than in females, and peak bone

  14. Cultural History and Cultural Materialism.

    Science.gov (United States)

    Berman, Ronald

    1990-01-01

    Historicism critiques cultural history and cultural materialism as a methodology for literary analysis. Questions the finality of interpretation, how original values change, and whether dramatic history implies actual history. Using Shakespearean plays, analyzes the power and politics of a play in relation to its audience; posits that cultural…

  15. Cultural History and Cultural Materialism.

    Science.gov (United States)

    Berman, Ronald

    1990-01-01

    Historicism critiques cultural history and cultural materialism as a methodology for literary analysis. Questions the finality of interpretation, how original values change, and whether dramatic history implies actual history. Using Shakespearean plays, analyzes the power and politics of a play in relation to its audience; posits that cultural…

  16. Digging culture and doing culture

    NARCIS (Netherlands)

    Andries van den Broek; Jos de Haan; Frank Huysmans

    2009-01-01

    Original title: Cultuurbewonderaars en cultuurbeoefenaars. There are people who love art and culture and there are people who practise it; people who enjoy it and people who are themselves creative in their leisure time. Who are these culture-lovers and practitioners? How has participation in

  17. Culture Matters

    Directory of Open Access Journals (Sweden)

    Gillian Warner-Søderholm

    2012-12-01

    Full Text Available Whether managers are concerned with financial issues, marketing, or human resource management (HRM, cultural values and practices do matter. The purpose of this article is to understand Norwegian managers’ cultural values within the cross-cultural landscape of her neighbors in the “Scandinavian cluster.” Clearly, subtle but disturbing differences may surface even when representatives from similar cultures work together. As a follow on from the GLOBE project, data based on the GLOBE instrument were collected on culture and communication values in Norway from 710 Norwegian middle managers for this present study. Although the Scandinavian cultures appear ostensibly similar, the results illustrate that research can reveal subtle but important cultural differences in nations that are similar yet dissimilar. All three Scandinavian societies appear intrinsically egalitarian; they appear to value low Power Distance, directness, and consensus in decision making and to promote Gender Egalitarianism. Nevertheless, there are significant differences in the degrees of commitment to these values by each individual Scandinavian partner. These differences need to be understood and appreciated to avoid misunderstandings.

  18. Cultural Spectrum

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Exorbitant Performance Fees ProhibitedThe Ministry of Culture has taken measures todiscourage performance artists from charging excessively for their stage appearances. According to the ministry, payment for performers and ticket prices must be in line with average con-

  19. Blood culture

    Science.gov (United States)

    Culture - blood ... A blood sample is needed . The site where blood will be drawn is first cleaned with an antiseptic such ... organism from the skin getting into (contaminating) the blood sample and causing a false-positive result (see ...

  20. Rectal culture

    Science.gov (United States)

    ... 2016:chap 283. Haines CF, Sears CL. Infectious enteritis and proctocolitis. In: Feldman M, Friedman LS, Brandt ... PA: Elsevier; 2017:chap 22. Read More Cryptosporidium enteritis Fecal culture Proctitis Review Date 5/11/2016 ...

  1. callus culture

    African Journals Online (AJOL)

    steve

    and KH2PO4 -NH4NO3 depletion was fatal to grape cells and resulted in formation ... Individual phenolic compounds found in the grape cell cultures were ...... Characterization of in vitro anthocyanin-producing sour cherry ... Process Biochem.

  2. Culture School

    Institute of Scientific and Technical Information of China (English)

    MATTHEW LIM

    2008-01-01

    @@ Until recently, employees posted abroad would, if they were lucky, receive some limited language training before they relocated. How they would cope with living in a completely new culture when they arrived was left up to them to figure out.

  3. Yangshao Culture

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Yangshao culture was born in the Neolithic Age. In 1921, archaeologists unearthed a number of chipped stone implements such as knives and axes; bone objects and everyday ceramic items. Thus Yangshao Village and its matriarchal society have

  4. Culture perspectives.

    Science.gov (United States)

    Locsin, Rozzano C

    2002-10-01

    All cultures have had means and techniques that express their immediate aims. The thing that interests me is that today, painters do not have to go to a subject matter outside of themselves. They work from a different source. They work from within. It seems to me that the modern artist cannot express this age, the airplane, the atom bomb, the radio, in the old form of the Renaissance or of any of the old cultures.

  5. Cultural Imports

    Institute of Scientific and Technical Information of China (English)

    1996-01-01

    FOREIGN commodities have flowed into China since the country opened its doors to the outside world. China is an expansive territory with a huge population offering a vast potential consumer market. There are absolutely no limits to the world of culture in China, with Chinese people having access to foreign films, dramas, music and books, all of which have helped to strengthen exchanges between Chinese and Western cultures.

  6. Correlation Between Vertebral Osteoporosis and Trabecular Bone Change in Patients with Lumbar Scoliosis%腰椎侧凸患者椎体骨小梁结构稀少与骨质疏松的相关性

    Institute of Scientific and Technical Information of China (English)

    张友; 赵尧; 朱晓勃; 陈岩

    2013-01-01

    Purpose To study the correlation between vertebral osteoporosis and trabecular bone change in adult patients with lumbar scoliosis. Materials and Methods One hundred patients with lumbar scoliosis diagnosed by using CT (patient group) and one hundred patients with a history of backleg pain but not diagnosed as lumbar scoliosis (control group) were enrolled. The CT readings of vertebra and vertebral trabecular bone volume to tissue volume (BV/TV) of patients in both groups were measured. Three-dimensional reconstruction of trabecular bone was performed to visualize its structure change. Results The measured CT and BV/TV values in patient group were significantly higher than those in control group (P<0.05). Three-dimensional volume rendering showed patient group had detectable trabecular discontinuities, reduced trabecular bone number, and less dense trabecular. There was a significant negative correlation between BV/TV and age (r=―0.513, P<0.01) for all the participants. Conclusion As a consequence of aging, the BV/TV value is reduced, the structure of spongy bone is changed and consequently, the incidence rate of vertebral osteoporosis is increased. The sparse trabecular structure, reduced trabecular number, and the structure change in spongy bone are the main reasons for adult lumbar scoliosis.%  目的观察成人腰椎侧凸患者椎体骨小梁的改变及其与骨质疏松的相关性.资料与方法收集经腰椎 CT 检查确诊的腰椎侧凸患者(病例组)及无腰椎侧凸的腰腿痛患者(对照组)各100例,分别测量两组受试者椎体 CT 值及椎体骨小梁容积百分比(BV/TV);同时重建骨小梁的三维图像,观察骨小梁的结构改变.结果病例组椎体 CT 值及 BV/TV 值均较对照组明显降低(P<0.05).容积再现三维图像显示,病例组患者骨小梁连续性中断,数目减少;对照组患者骨小梁相对致密.所有受试者 BV/TV 值与年龄呈负相关(r=―0.513, P<0.01).

  7. Urine culture - catheterized specimen

    Science.gov (United States)

    Culture - urine - catheterized specimen; Urine culture - catheterization; Catheterized urine specimen culture ... urinary tract infections may be found in the culture. This is called a contaminant. You may not ...

  8. Cultural tourism and tourism cultures

    DEFF Research Database (Denmark)

    Ooi, Can-Seng

    Presenting a comprehensive and dynamic understanding of cultural tourism, this volume examines cultural mediators and how they help tourists appreciate foreign cultures. It also shows how tourism experiences are strategically crafted by mediators, the complexity of the mediation process, and how...... various products are mediated differently. A number of different products are investigated, including destination brand identities, "living" cultures and everyday life, art and history. The author illustrates his arguments by comparing the tourism strategies of Copenhagen and Singapore, and demonstrates...... how tourism is an agent for social change. The author also offers an original and refreshing way of understanding tourist behaviour through the concept of the "versatile tourist". The book's empirical cases and dialogic framework provide new and deep insights into tourism activities. In his...

  9. A Cultural Sexuality or a Sexual Culture?

    NARCIS (Netherlands)

    Vandermeersch, Patrick

    1990-01-01

    P. Vandermeersch, A Cultural Sexuality or a Sexual Culture? In: F. VAN DE VIJVER & G. HUTSCHEMAEKERS (ed.), The Investigation of Culture. Current Issues in Cultural Psychology, Tilburg, Tilburg University Press, 1990, 43-58.

  10. Cultural Robotics: The Culture of Robotics and Robotics in Culture

    OpenAIRE

    2013-01-01

    In this paper, we have investigated the concept of "Cultural Robotics" with regard to the evolution of social into cultural robots in the 21st Century. By defining the concept of culture, the potential development of a culture between humans and robots is explored. Based on the cultural values of the robotics developers, and the learning ability of current robots, cultural attributes in this regard are in the process of being formed, which would define the new concept of cultural robotics. Ac...