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Sample records for cortical bone potential

  1. Demineralized Freeze-Dried Bovine Cortical Bone: Its Potential for Guided Bone Regeneration Membrane

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    David B. Kamadjaja

    2017-01-01

    Full Text Available Background. Bovine pericardium collagen membrane (BPCM had been widely used in guided bone regeneration (GBR whose manufacturing process usually required chemical cross-linking to prolong its biodegradation. However, cross-linking of collagen fibrils was associated with poorer tissue integration and delayed vascular invasion. Objective. This study evaluated the potential of bovine cortical bone collagen membrane for GBR by evaluating its antigenicity potential, cytotoxicity, immune and tissue response, and biodegradation behaviors. Material and Methods. Antigenicity potential of demineralized freeze-dried bovine cortical bone membrane (DFDBCBM was done with histology-based anticellularity evaluation, while cytotoxicity was analyzed using MTT Assay. Evaluation of immune response, tissue response, and biodegradation was done by randomly implanting DFDBCBM and BPCM in rat’s subcutaneous dorsum. Samples were collected at 2, 5, and 7 days and 7, 14, 21, and 28 days for biocompatibility and tissue response-biodegradation study, respectively. Result. DFDBCBM, histologically, showed no retained cells; however, it showed some level of in vitro cytotoxicity. In vivo study exhibited increased immune response to DFDBCBM in early healing phase; however, normal tissue response and degradation rate were observed up to 4 weeks after DFDBCBM implantation. Conclusion. Demineralized freeze-dried bovine cortical bone membrane showed potential for clinical application; however, it needs to be optimized in its biocompatibility to fulfill all requirements for GBR membrane.

  2. Spaceflight-relevant types of ionizing radiation and cortical bone: Potential LET effect?

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    Lloyd, Shane A.J.; Bandstra, Eric R.; Travis, Neil D.; Nelson, Gregory A.; Bourland, J. Daniel; Pecaut, Michael J.; Gridley, Daila S.; Willey, Jeffrey S.; Bateman, Ted A.

    2008-01-01

    Extended exposure to microgravity conditions results in significant bone loss. Coupled with radiation exposure, this phenomenon may place astronauts at a greater risk for mission-critical fractures. In a previous study, we identified a profound and prolonged loss of trabecular bone (29−39%) in mice following exposure to an acute, 2 Gy dose of radiation simulating both solar and cosmic sources. However, because skeletal strength depends on trabecular and cortical bone, accurate assessment of strength requires analysis of both bone compartments. The objective of the present study was to examine various properties of cortical bone in mice following exposure to multiple types of spaceflight-relevant radiation. Nine-week old, female C57BL/6 mice were sacrificed 110 days after exposure to a single, whole body, 2 Gy dose of gamma, proton, carbon, or iron radiation. Femora were evaluated with biomechanical testing, microcomputed tomography, quantitative histomorphometry, percent mineral content, and micro-hardness analysis. Compared to non-irradiated controls, there were significant differences compared to carbon or iron radiation for only fracture force, medullary area and mineral content. A greater differential effect based on linear energy transfer (LET) level may be present: high-LET (carbon or iron) particle irradiation was associated with a decline in structural properties (maximum force, fracture force, medullary area, and cortical porosity) and mineral composition compared to low-LET radiation (gamma and proton). Bone loss following irradiation appears to be largely specific to trabecular bone and may indicate unique biological microenvironments and microdosimetry conditions. However, the limited time points examined and non-haversian skeletal structure of the mice employed highlight the need for further investigation. PMID:19122806

  3. Quantitative radiology: radiogrammetry of cortical bone.

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    Dequeker, J

    1976-11-01

    Based on personal experience and data in the literature, an overview is given of radiogrammetry of cortical bone of the second metacarpal. There is a within- and between-observer error which amounts respectively to 1.2 and 1.5% for the outer diameter and 4.8 and 6.4% for the inner diameter. The systematic + or-- trend between observers indicates that one observer working according to certain defined rules obtains the most reliable results. There is a large variability in amount of bone within one age and sex group which is partly due to skeletal size differences, are insufficient since skeletal size differences still exist. The variability is reduced when the data are divided into strata of skeletal size. Since cortical area shows the best correlation with outer diameter within each age group and since cortical area represents best the ash content of the bones the values of this index are most suited to be grouped according to outer diameter. In differentiating pathological from physiological bone loss this procedure is an improvement on the previously published indices of amount of bone. When comparing different populations this method has advantages since skeletal size differences are eliminated. Comparing seven populations it was found that populations living in the United States of America have more bone for a given skeletal size than populations in Europe or Nigeria. Bone loss with age is a general phenomenon but differences in rate of loss are observed between the sexes and between ethnic different populations. The decrease of bone mass is faster after the age of 50 years in woman than in men. Blacks living in the United States loose less bone with age than whites. Radiogrammetry of cortical bone in groups gives useful information on bond remodelling during ageing and in pathological conditions. At an individual level, however, it is difficult to evaluate changes on a short term basis with radiogrammetry. Radiogrammetry of cortical bone is a simple and

  4. Genome-wide association meta-analysis of cortical bone mineral density unravels allelic heterogeneity at the RANKL locus and potential pleiotropic effects on bone.

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    Lavinia Paternoster

    2010-11-01

    Full Text Available Previous genome-wide association (GWA studies have identified SNPs associated with areal bone mineral density (aBMD. However, this measure is influenced by several different skeletal parameters, such as periosteal expansion, cortical bone mineral density (BMD(C cortical thickness, trabecular number, and trabecular thickness, which may be under distinct biological and genetic control. We have carried out a GWA and replication study of BMD(C, as measured by peripheral quantitative computed tomography (pQCT, a more homogenous and valid measure of actual volumetric bone density. After initial GWA meta-analysis of two cohorts (ALSPAC n = 999, aged ∼15 years and GOOD n = 935, aged ∼19 years, we attempted to replicate the BMD(C associations that had p<1×10(-5 in an independent sample of ALSPAC children (n = 2803 and in a cohort of elderly men (MrOS Sweden, n = 1052. The rs1021188 SNP (near RANKL was associated with BMD(C in all cohorts (overall p = 2×10(-14, n = 5739. Each minor allele was associated with a decrease in BMD(C of ∼0.14SD. There was also evidence for an interaction between this variant and sex (p = 0.01, with a stronger effect in males than females (at age 15, males -6.77mg/cm(3 per C allele, p = 2×10(-6; females -2.79 mg/cm(3 per C allele, p = 0.004. Furthermore, in a preliminary analysis, the rs1021188 minor C allele was associated with higher circulating levels of sRANKL (p<0.005. We show this variant to be independent from the previously aBMD associated SNP (rs9594738 and possibly from a third variant in the same RANKL region, which demonstrates important allelic heterogeneity at this locus. Associations with skeletal parameters reflecting bone dimensions were either not found or were much less pronounced. This finding implicates RANKL as a locus containing variation associated with volumetric bone density and provides further insight into the mechanism by which the RANK/RANKL/OPG pathway

  5. Osteocyte lacunar properties in rat cortical bone

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    Bach-Gansmo, Fiona Linnea; Weaver, James C.; Jensen, Mads Hartmann

    2015-01-01

    to osteocyte function, osteocyte lacunar properties such as volume, shape, orientation, and density are now frequently reported in studies investigating osteocyte activity. Despite this increasing interest in lacunar morphometrics, many studies show a large spread in such values, suggesting a large inter......-species but also inter-site variation in lacunar properties. Here, osteocyte lacunae in rat cortical bone have been studied using synchrotron radiation micro computed tomography (SR μCT) and backscattered electron (BE) microscopy. Quantitative lacunar geometric characteristics are reported based on the synchrotron...... radiation data, differentiating between circumferential lamellar bone and a central, more disordered bone type. From these studies, no significant differences were found in lacunar volumes between lamellar and central bone, whereas significant differences in lacunar orientation, shape and density values...

  6. The myokine irisin increases cortical bone mass

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    Colaianni, Graziana; Cuscito, Concetta; Mongelli, Teresa; Pignataro, Paolo; Buccoliero, Cinzia; Liu, Peng; Lu, Ping; Sartini, Loris; Di Comite, Mariasevera; Mori, Giorgio; Di Benedetto, Adriana; Brunetti, Giacomina; Yuen, Tony; Sun, Li; Reseland, Janne E.; Colucci, Silvia; New, Maria I.; Zaidi, Mone; Cinti, Saverio; Grano, Maria

    2015-01-01

    It is unclear how physical activity stimulates new bone synthesis. We explored whether irisin, a newly discovered myokine released upon physical activity, displays anabolic actions on the skeleton. Young male mice were injected with vehicle or recombinant irisin (r-irisin) at a low cumulative weekly dose of 100 µg kg−1. We observed significant increases in cortical bone mass and strength, notably in cortical tissue mineral density, periosteal circumference, polar moment of inertia, and bending strength. This anabolic action was mediated primarily through the stimulation of bone formation, but with parallel notable reductions in osteoclast numbers. The trabecular compartment of the same bones was spared, as were vertebrae from the same mice. Higher irisin doses (3,500 µg kg−1 per week) cause browning of adipose tissue; this was not seen with low-dose r-irisin. Expectedly, low-dose r-irisin modulated the skeletal genes, Opn and Sost, but not Ucp1 or Pparγ expression in white adipose tissue. In bone marrow stromal cell cultures, r-irisin rapidly phosphorylated Erk, and up-regulated Atf4, Runx2, Osx, Lrp5, β-catenin, Alp, and Col1a1; this is consistent with a direct receptor-mediated action to stimulate osteogenesis. We also noted that, although the irisin precursor Fndc5 was expressed abundantly in skeletal muscle, other sites, such as bone and brain, also expressed Fndc5, albeit at low levels. Furthermore, muscle fibers from r-irisin–injected mice displayed enhanced Fndc5 positivity, and irisin induced Fdnc5 mRNA expression in cultured myoblasts. Our data therefore highlight a previously unknown action of the myokine irisin, which may be the molecular entity responsible for muscle–bone connectivity. PMID:26374841

  7. Cortical bone total ossicular replacement prosthesis

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    Manu Malhotra

    2014-01-01

    Full Text Available Objectives: Evaluate an autologous cortical bone total ossicular replacement prosthesis (B TORP made of cortical bone for cost effective and sustainable hearing results. Materials and Methods: A prospective study was undertaken in the patients who underwent tympanoplasty with new B-TORP from January 2011 to December 2011. All patients had an absent superstructure of the stapes and long process of the incus due to chronic otitis media. Totally 40 patients were evaluated. Hearing results were evaluated using four-frequency average pure tone air conduction and air-bone gap (ABG measured at 0.5, 1, 2, and 3 kHz after a period of 12 months. Pre- and post-operative continuous variables were compared using a paired t-test and data from unequal groups were assessed for significant differences using unpaired t-test. Results: Successful rehabilitation of the ABG to 20 dB or less was achieved in 95% of patients. Overall mean improvement in ABG was 25.8 ± 5.6 dB, which was statistically significant (t = 26.8, P 0.5. Conclusion: The new autologous B-TORP provides sustainable hearing improvement and is bio-compatible, stable, and magnetic resonance imaging compatible.

  8. Thermographic stress analysis in cortical bone.

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    Vanderby, R; Kohles, S S

    1991-11-01

    Under adiabatic (or near adiabatic) conditions a volumetric change in an elastic material will produce a corresponding change in temperature. Based upon this principle, thermographic stress analysis (TSA) measures changes in surface heat flux (which are related to changes in surface temperature) and relates them to a coupled form of strains or stresses. To demonstrate the feasibility of using this technique for biomechanical applications, we thermographically measured heat flux from loaded specimens of cortical bone and correlated the results with strain gage data. Regular parallelepipeds were cut from the cortex of bovine femora and loaded sinusoidally at 20 Hz. At this rate of loading, mechanically induced changes in surface temperature could be sampled (via heat flux) prior to a measureable attenuation of the thermoelastic effect. Correlation coefficients demonstrated a significant linear relationship between TSA and measured and computed mechanical parameters (stress, strain, first strain invariant, and strain energy density). TSA therefore appears to be a promising technology for experimental stress analysis in cortical bone.

  9. Impact of lanthanum carbonate on cortical bone in dialysis patients with adynamic bone disease.

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    Yajima, Aiji; Inaba, Masaaki; Tominaga, Yoshihiro; Tanaka, Motoko; Otsubo, Shigeru; Nitta, Kosaku; Ito, Akemi; Satoh, Shigeru

    2013-04-01

    Among the most serious problems in patients with chronic kidney disease (CKD) is fragility of cortical bone caused by cortical thinning and increased cortical porosity; the cortical fragility is sometimes irreversible, with fractures generally initiating from cortical bone. Therefore, development of treatments for problems of cortical bone is urgently desired. Cortical bone has the three surfaces, including the periosteal surface, intracortical spaces and endocortical surface. Bone turnover at the endocortical surface and intracortical resorption spaces are increased as compared with that at cancellous surface. Bone growth sometimes depends on apposition at the periosteal surface. We treated hyperphosphatemia in two hemodialysis patients with adynamic bone disease with 750-1500 mg/day of lanthanum carbonate, which is a non-calcium containing phosphate binder; the treatment resulted in a decrease of the serum phosphorus levels (P levels), without significant change of the serum intact parathyroid hormone levels. We now report that treatment of these patients with lanthanum carbonate increased mineralization of the periosteal surface, increased bone mass within the intracortical resorption spaces and increased mineralization of the minimodeling surface at the endocortical surface. In addition, woven bone volume in cortical bone was decreased and mineralization of bone units, namely, osteons, was increased. Although these findings were not observed across all surfaces of the cortical bone in the patients, it is expected that lanthanum carbonate would increase the cortical stability in CKD patients, with consequent reduction in the fracture rate in these patients.

  10. Bone balance within a cortical BMU: local controls of bone resorption and formation.

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    David W Smith

    Full Text Available Maintaining bone volume during bone turnover by a BMU is known as bone balance. Balance is required to maintain structural integrity of the bone and is often dysregulated in disease. Consequently, understanding how a BMU controls bone balance is of considerable interest. This paper develops a methodology for identifying potential balance controls within a single cortical BMU. The theoretical framework developed offers the possibility of a directed search for biological processes compatible with the constraints of balance control. We first derive general control constraint equations and then introduce constitutive equations to identify potential control processes that link key variables that describe the state of the BMU. The paper describes specific local bone volume balance controls that may be associated with bone resorption and bone formation. Because bone resorption and formation both involve averaging over time, short-term fluctuations in the environment are removed, leaving the control systems to manage deviations in longer-term trends back towards their desired values. The length of time for averaging is much greater for bone formation than for bone resorption, which enables more filtering of variability in the bone formation environment. Remarkably, the duration for averaging of bone formation may also grow to control deviations in long-term trends of bone formation. Providing there is sufficient bone formation capacity by osteoblasts, this leads to an extraordinarily robust control mechanism that is independent of either osteoblast number or the cellular osteoid formation rate. A complex picture begins to emerge for the control of bone volume. Different control relationships may achieve the same objective, and the 'integration of information' occurring within a BMU may be interpreted as different sets of BMU control systems coming to the fore as different information is supplied to the BMU, which in turn leads to different observable

  11. Bone balance within a cortical BMU: local controls of bone resorption and formation.

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    Smith, David W; Gardiner, Bruce S; Dunstan, Colin

    2012-01-01

    Maintaining bone volume during bone turnover by a BMU is known as bone balance. Balance is required to maintain structural integrity of the bone and is often dysregulated in disease. Consequently, understanding how a BMU controls bone balance is of considerable interest. This paper develops a methodology for identifying potential balance controls within a single cortical BMU. The theoretical framework developed offers the possibility of a directed search for biological processes compatible with the constraints of balance control. We first derive general control constraint equations and then introduce constitutive equations to identify potential control processes that link key variables that describe the state of the BMU. The paper describes specific local bone volume balance controls that may be associated with bone resorption and bone formation. Because bone resorption and formation both involve averaging over time, short-term fluctuations in the environment are removed, leaving the control systems to manage deviations in longer-term trends back towards their desired values. The length of time for averaging is much greater for bone formation than for bone resorption, which enables more filtering of variability in the bone formation environment. Remarkably, the duration for averaging of bone formation may also grow to control deviations in long-term trends of bone formation. Providing there is sufficient bone formation capacity by osteoblasts, this leads to an extraordinarily robust control mechanism that is independent of either osteoblast number or the cellular osteoid formation rate. A complex picture begins to emerge for the control of bone volume. Different control relationships may achieve the same objective, and the 'integration of information' occurring within a BMU may be interpreted as different sets of BMU control systems coming to the fore as different information is supplied to the BMU, which in turn leads to different observable BMU behaviors.

  12. Effect of porosity, tissue density, and mechanical properties on radial sound speed in human cortical bone

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    Eneh, C. T. M., E-mail: chibuzor.eneh@uef.fi, E-mail: markus.malo@uef.fi, E-mail: janne.karjalainen@boneindex.fi, E-mail: jukka.liukkonen@gmail.com, E-mail: juha.toyras@uef.fi; Töyräs, J., E-mail: chibuzor.eneh@uef.fi, E-mail: markus.malo@uef.fi, E-mail: janne.karjalainen@boneindex.fi, E-mail: jukka.liukkonen@gmail.com, E-mail: juha.toyras@uef.fi; Jurvelin, J. S., E-mail: jukka.jurvelin@uef.fi [Department of Applied Physics, University of Eastern Finland, P.O. Box 1627, Kuopio FI-70211, Finland and Diagnostic Imaging Center, Kuopio University Hospital, P.O. Box 100, Kuopio FI-70029 (Finland); Malo, M. K. H., E-mail: chibuzor.eneh@uef.fi, E-mail: markus.malo@uef.fi, E-mail: janne.karjalainen@boneindex.fi, E-mail: jukka.liukkonen@gmail.com, E-mail: juha.toyras@uef.fi; Liukkonen, J., E-mail: chibuzor.eneh@uef.fi, E-mail: markus.malo@uef.fi, E-mail: janne.karjalainen@boneindex.fi, E-mail: jukka.liukkonen@gmail.com, E-mail: juha.toyras@uef.fi [Department of Applied Physics, University of Eastern Finland, P.O. Box 1627, Kuopio FI-70211 (Finland); Karjalainen, J. P., E-mail: chibuzor.eneh@uef.fi, E-mail: markus.malo@uef.fi, E-mail: janne.karjalainen@boneindex.fi, E-mail: jukka.liukkonen@gmail.com, E-mail: juha.toyras@uef.fi [Bone Index Finland Ltd., P.O. Box 1188, Kuopio FI-70211 (Finland)

    2016-05-15

    Purpose: The purpose of this study was to investigate the effect of simultaneous changes in cortical porosity, tissue mineral density, and elastic properties on radial speed of sound (SOS) in cortical bone. The authors applied quantitative pulse-echo (PE) ultrasound techniques that hold much potential especially for screening of osteoporosis at primary healthcare facilities. Currently, most PE measurements of cortical thickness, a well-known indicator of fracture risk, use a predefined estimate for SOS in bone to calculate thickness. Due to variation of cortical bone porosity, the use of a constant SOS value propagates to an unknown error in cortical thickness assessment by PE ultrasound. Methods: The authors conducted 2.25 and 5.00 MHz focused PE ultrasound time of flight measurements on femoral diaphyses of 18 cadavers in vitro. Cortical porosities of the samples were determined using microcomputed tomography and related to SOS in the samples. Additionally, the effect of cortical bone porosity and mechanical properties of the calcified matrix on SOS was investigated using numerical finite difference time domain simulations. Results: Both experimental measurements and simulations demonstrated significant negative correlation between radial SOS and cortical porosity (R{sup 2} ≥ 0.493, p < 0.01 and R{sup 2} ≥ 0.989, p < 0.01, respectively). When a constant SOS was assumed for cortical bone, the error due to variation of cortical bone porosity (4.9%–16.4%) was about 6% in the cortical thickness assessment in vitro. Conclusions: Use of a predefined, constant value for radial SOS in cortical bone, i.e., neglecting the effect of measured variation in cortical porosity, propagated to an error of 6% in cortical thickness. This error can be critical as characteristic cortical thinning of 1.10% ± 1.06% per yr decreases bending strength of the distal radius and results in increased fragility in postmenopausal women. Provided that the cortical porosity can be estimated

  13. Swine cortical and cancellous bone: histomorphometric and densitometric characterisation

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    Maria Elena Andreis

    2017-06-01

    Full Text Available Introduction: Swine bone morphology, composition and remodelling are similar to humans’, therefore they are considered good models in bone-related research. They have been used for several studies involving bone growth, bone and cartilage fractures and femoral head osteonecrosis. Nevertheless, the literature about pig normal bone features is incomplete. This work aims to fill the literature gaps on the microarchitecture and Bone Mineral Density (BMD of swine femoral diaphysis and distal epiphysis and tibial plateau and diaphysis. Materials and methods: Five hind limbs were collected from slaughtered 80-100 kg pigs. Microscopic analysis of cortical and cancellous bone from middle/distal femur and proximal/middle tibia was performed to determine basic histomorphometric parameters at different sites. Dual-energy X-Rays Absorptiometry was also employed to evaluate BMD. ANOVA and correlation between BMD, bone area (BA and cortical thickness were performed. Results and discussion: Diaphyseal cortical bone was mostly plexiform both in the tibia and the femur; primary/secondary osteons without clear organization were also found. Mean values for bone area, bone perimeter, trabecular width, number and separation and BMD at different anatomical sites were defined. No significant difference was found for these values at different anatomical sites. BMD proved to be positively correlated with cortical thickness (r=0,80; p<0,01. Despite the small sample size, these results seem homogeneous. They could therefore represent reference values for normal bone parameters in pigs. Applied anatomy and regenerative medicine, in fact, demand very precise information about bone micromorphology, composition and density to provide reliable indication in bone substitutes building. Moreover, since the interpretation of bone abnormalities is based on mastering normal bone characteristics, the definition of reference parameters is mandatory to avoid misinterpretation and

  14. The Effects of Obesity on Murine Cortical Bone

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    Martin, Sophi

    This dissertation details the effects of obesity on the mechanical properties and structure of cortical bone. Obesity is associated with greater bone mineral content that might be expected to protect against fracture, which has been observed in adults. Paradoxically however, the incidence of bone fractures has been found to increase in overweight and obese children and adolescents. Femora from adolescent and adult mice fed a high-fat diet are investigated for changes in shape, tissue structure, as well as tissue-level and whole-bone mechanical properties. Results indicate increased bone size, reduced size-independent mechanical properties, but maintained size-dependent mechanical properties. Other changes in cortical bone response to obesity are observed with advancing age. This study indicates that bone quantity and bone quality play important compensatory roles in determining fracture risk, and that fracture risk may not be lessened for adults as previously thought.

  15. Lumbar pedicle cortical bone trajectory screw

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    Song Tengfei; Wellington K Hsu; Ye Tianwen

    2014-01-01

    Objective The purpose of this study was to demonstrate the lumbar pedicle cortical bone trajectory (CBT) screw fixation technique,a new fixation technique for lumbar surgery.Data sources The data analyzed in this review are mainly from articles reported in PubMed published from 1994 to 2014.Study selection Original articles and critical reviews relevant to CBT technique and lumbar pedicle fixation were selected.Results CBT technique was firstly introduced as a new fixation method for lumbar pedicle surgery in 2009.The concepts,morphometric study,biomechanical characteristics and clinical applications of CBT technique were reviewed.The insertional point of CBT screw is located at the lateral point of the pars interarticularis,and its trajectory follows a caudocephalad path sagittally and a laterally directed path in the transverse plane.CBT technique can be used for posterior fixation during lumbar fusion procedures.This technique is a minimally invasive surgery,which affords better biomechanical stability,fixation strength and surgical safety.Therefore,CBT technique has the greatest benefit in lumbar pedicle surgery for patients with osteoporosis and obesity.Conclusion CBT technique is a better alternative option of lumbar pedicle fixation,especially for patients with osteoporosis and obesity.

  16. Probiotics protect mice from ovariectomy-induced cortical bone loss.

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    Ohlsson, Claes; Engdahl, Cecilia; Fåk, Frida; Andersson, Annica; Windahl, Sara H; Farman, Helen H; Movérare-Skrtic, Sofia; Islander, Ulrika; Sjögren, Klara

    2014-01-01

    The gut microbiota (GM) modulates the hosts metabolism and immune system. Probiotic bacteria are defined as live microorganisms which when administered in adequate amounts confer a health benefit on the host and can alter the composition of the GM. Germ-free mice have increased bone mass associated with reduced bone resorption indicating that the GM also regulates bone mass. Ovariectomy (ovx) results in bone loss associated with altered immune status. The purpose of this study was to determine if probiotic treatment protects mice from ovx-induced bone loss. Mice were treated with either a single Lactobacillus (L) strain, L. paracasei DSM13434 (L. para) or a mixture of three strains, L. paracasei DSM13434, L. plantarum DSM 15312 and DSM 15313 (L. mix) given in the drinking water during 6 weeks, starting two weeks before ovx. Both the L. para and the L. mix treatment protected mice from ovx-induced cortical bone loss and bone resorption. Cortical bone mineral content was higher in both L. para and L. mix treated ovx mice compared to vehicle (veh) treated ovx mice. Serum levels of the resorption marker C-terminal telopeptides and the urinary fractional excretion of calcium were increased by ovx in the veh treated but not in the L. para or the L. mix treated mice. Probiotic treatment reduced the expression of the two inflammatory cytokines, TNFα and IL-1β, and increased the expression of OPG, a potent inhibitor of osteoclastogenesis, in cortical bone of ovx mice. In addition, ovx decreased the frequency of regulatory T cells in bone marrow of veh treated but not probiotic treated mice. In conclusion, treatment with L. para or the L. mix prevents ovx-induced cortical bone loss. Our findings indicate that these probiotic treatments alter the immune status in bone resulting in attenuated bone resorption in ovx mice.

  17. Probiotics protect mice from ovariectomy-induced cortical bone loss.

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    Claes Ohlsson

    Full Text Available The gut microbiota (GM modulates the hosts metabolism and immune system. Probiotic bacteria are defined as live microorganisms which when administered in adequate amounts confer a health benefit on the host and can alter the composition of the GM. Germ-free mice have increased bone mass associated with reduced bone resorption indicating that the GM also regulates bone mass. Ovariectomy (ovx results in bone loss associated with altered immune status. The purpose of this study was to determine if probiotic treatment protects mice from ovx-induced bone loss. Mice were treated with either a single Lactobacillus (L strain, L. paracasei DSM13434 (L. para or a mixture of three strains, L. paracasei DSM13434, L. plantarum DSM 15312 and DSM 15313 (L. mix given in the drinking water during 6 weeks, starting two weeks before ovx. Both the L. para and the L. mix treatment protected mice from ovx-induced cortical bone loss and bone resorption. Cortical bone mineral content was higher in both L. para and L. mix treated ovx mice compared to vehicle (veh treated ovx mice. Serum levels of the resorption marker C-terminal telopeptides and the urinary fractional excretion of calcium were increased by ovx in the veh treated but not in the L. para or the L. mix treated mice. Probiotic treatment reduced the expression of the two inflammatory cytokines, TNFα and IL-1β, and increased the expression of OPG, a potent inhibitor of osteoclastogenesis, in cortical bone of ovx mice. In addition, ovx decreased the frequency of regulatory T cells in bone marrow of veh treated but not probiotic treated mice. In conclusion, treatment with L. para or the L. mix prevents ovx-induced cortical bone loss. Our findings indicate that these probiotic treatments alter the immune status in bone resulting in attenuated bone resorption in ovx mice.

  18. Buccal cortical bone thickness on CBCT for mini-implant

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    Goo, Jong Gook; Lim, Sung Hoon; Lee, Byoung Jin; Kim, Jae Duk [School of Dentistry, Chosun University, Gwangju (Korea, Republic of)

    2010-12-15

    Cortical bone thickness is one of the important factor in mini-implant stability. This study was performed to investigate the buccal cortical bone thickness at every interdental area as an aid in planning mini-implant placement. Two-dimensional slices at every interdental area were selected from the cone-beam computed tomography scans of 20 patients in third decade. Buccal cortical bone thickness was measured at 2, 4, and 6 mm levels from the alveolar crest in the interdental bones of posterior regions of both jaws using the plot profile function of Ez3D2009TM (Vatech, Yongin, Korea). The results were analyzed using by Mann-Whitney test. Buccal cortical bone was thicker in the mandible than in the maxilla. The thickness increased with further distance from the alveolar crest in the maxilla and with coming from the posterior to anterior region in the mandible (p?0.01). The maximum CT value showed an increasing tendency with further distance from the alveolar crest and with coming from posterior to anterior region in both jaws. Interdental buccal cortical bone thickness varied in both jaws, however our study showed a distinct tendency. We expect that these results could be helpful for the selection and preparation of mini-implant sites.

  19. Independent measurement of femoral cortical thickness and cortical bone density using clinical CT.

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    Treece, G M; Gee, A H

    2015-02-01

    The local structure of the proximal femoral cortex is of interest since both fracture risk, and the effects of various interventions aimed at reducing that risk, are associated with cortical properties focused in particular regions rather than dispersed over the whole bone. Much of the femoral cortex is less than 3mm thick, appearing so blurred in clinical CT that its actual density is not apparent in the data, and neither thresholding nor full-width half-maximum techniques are capable of determining its width. Our previous work on cortical bone mapping showed how to produce more accurate estimates of cortical thickness by assuming a fixed value of the cortical density for each hip. However, although cortical density varies much less over the proximal femur than thickness, what little variation there is leads to errors in thickness measurement. In this paper, we develop the cortical bone mapping technique by exploiting local estimates of imaging blur to correct the global density estimate, thus providing a local density estimate as well as more accurate estimates of thickness. We also consider measurement of cortical mass surface density and the density of trabecular bone immediately adjacent to the cortex. Performance is assessed with ex vivo clinical QCT scans of proximal femurs, with true values derived from high resolution HRpQCT scans of the same bones. We demonstrate superior estimation of thickness than is possible with alternative techniques (accuracy 0.12 ± 0.39 mm for cortices in the range 1-3mm), and that local cortical density estimation is feasible for densities >800 mg/cm(3).

  20. Increased intra-cortical porosity reduces bone stiffness and strength in pediatric patients with osteogenesis imperfecta.

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    Vardakastani, V; Saletti, D; Skalli, W; Marry, P; Allain, J M; Adam, C

    2014-12-01

    Osteogenesis imperfecta (OI) is a heritable disease occurring in one out of every 20,000 births. Although it is known that Type I collagen mutation in OI leads to increased bone fragility, the mechanism of this increased susceptibility to fracture is not clear. The aim of this study was to assess the microstructure of cortical bone fragments from patients with osteogenesis imperfecta (OI) using polarized light microscopy, and to correlate microstructural observations with the results of previously performed mechanical compression tests on bone from the same source. Specimens of cortical bone were harvested from the lower limbs of three (3) OI patients at the time of surgery, and were divided into two groups. Group 1 had been subjected to previous micro-mechanical compression testing, while Group 2 had not been subjected to any prior testing. Polarized light microscopy revealed disorganized bone collagen architecture as has been previously observed, as well as a large increase in the areal porosity of the bone compared to typical values for healthy cortical bone, with large (several hundred micron sized), asymmetrical pores. Importantly, the areal porosity of the OI bone samples in Group 1 appears to correlate strongly with their previously measured apparent Young's modulus and compressive strength. Taken together with prior nanoindentation studies on OI bone tissue, the results of this study suggest that increased intra-cortical porosity is responsible for the reduction in macroscopic mechanical properties of OI cortical bone, and therefore that in vivo imaging modalities with resolutions of ~100 μm or less could potentially be used to non-invasively assess bone strength in OI patients. Although the number of subjects in this study is small, these results highlight the importance of further studies in OI bone by groups with access to human OI tissue in order to clarify the relationship between increased porosity and reduced macroscopic mechanical integrity.

  1. The importance of murine cortical bone microstructure for microcrack initiation and propagation.

    Science.gov (United States)

    Voide, R; Schneider, P; Stauber, M; van Lenthe, G H; Stampanoni, M; Müller, R

    2011-12-01

    In order to better understand bone postyield behavior and consequently bone failure behavior, this study aimed first to investigate cortical bone microstructure and second, to relate cortical bone microstructure to microdamage initiation and propagation in C57BL/6 (B6) and C3H/He (C3H) mice; two murine inbred strains known for their differences in bone phenotype. Murine femora of B6 and C3H were loaded axially under compression in a stepwise manner. For each loading step, 3D data sets at a nominal resolution of 700 nm were acquired by means of synchrotron radiation-based computed tomography. Cortical bone microstructure was divided into three phases: the canal network, the osteocyte lacunar system, and microdamage. Canal volume density and canal unit volume both correlated highly to crack number density (canal volume density: R(2)=0.64, pcanal unit volume: R(2)=0.75, pcanal units in C3H bone were responsible for more microdamage accumulation compared to B6 bones. This more pronounced microdamage accumulation due to large intracortical bone voids, which eventually leads to a fatal macrocrack (fracture), represents a potential contributing factor to the higher incidence of bone fractures in the elderly. Copyright © 2011 Elsevier Inc. All rights reserved.

  2. Disuse exaggerates the detrimental effects of alcohol on cortical bone

    Science.gov (United States)

    Hefferan, Theresa E.; Kennedy, Angela M.; Evans, Glenda L.; Turner, Russell T.

    2003-01-01

    BACKGROUND: Alcohol abuse is associated with an increased risk for osteoporosis. However, comorbidity factors may play an important role in the pathogenesis of alcohol-related bone fractures. Suboptimal mechanical loading of the skeleton, an established risk factor for bone loss, may occur in some alcohol abusers due to reduced physical activity, muscle atrophy, or both. The effect of alcohol consumption and reduced physical activity on bone metabolism has not been well studied. The purpose of this study was to determine whether mechanical disuse alters bone metabolism in a rat model for chronic alcohol abuse. METHODS: Alcohol was administered in the diet (35% caloric intake) of 6-month-old male rats for 4 weeks. Rats were hindlimb-unloaded the final 2 weeks of the experiment to prevent dynamic weight bearing. Afterward, cortical bone histomorphometry was evaluated at the tibia-fibula synostosis. RESULTS: At the periosteal surface of the tibial diaphysis, alcohol and hindlimb unloading independently decreased the mineralizing perimeter, mineral apposition rate, and bone formation rate. In addition, alcohol, but not hindlimb unloading, increased endocortical bone resorption. The respective detrimental effects of alcohol and hindlimb unloading to inhibit bone formation were additive; there was no interaction between the two variables. CONCLUSIONS: Reduced weight bearing accentuates the detrimental effects of alcohol on cortical bone in adult male rats by further inhibiting bone formation. This finding suggests that reduced physical activity may be a comorbidity factor for osteoporosis in alcohol abusers.

  3. Architecture and microstructure of cortical bone in reconstructed canine mandibles after bone transport distraction osteogenesis.

    Science.gov (United States)

    Zapata, Uriel; Halvachs, Emily K; Dechow, Paul C; Elsalanty, Mohammed E; Opperman, Lynne A

    2011-11-01

    Reconstruction of the canine mandible using bone transport distraction osteogenesis has been shown to be a suitable method for correcting segmental bone defects produced by cancer, gunshots, and trauma. Although the mechanical quality of the new regenerate cortical bone seems to be related to the mineralization process, several questions regarding the microstructural patterns of the new bony tissue remain unanswered. The purpose of this study was to quantify any microstructural differences that may exist between the regenerate and control cortical bone. Five adult American foxhound dogs underwent unilateral bone transport distraction of the mandible to repair bone defects of 30-35 mm. Animals were killed 12 weeks after the beginning of the consolidation period. Fourteen cylindrical cortical samples were extracted from the superior, medial, and inferior aspects of the lingual and buccal plates of the reconstructed aspect of the mandible, and 21 specimens were collected similarly from the contralateral aspect of the mandible. Specimens were evaluated using histomorphometric and micro-computed tomographic techniques to compare their microstructure. Except for differences in haversian canal area, histomorphometric analyses suggested no statistical differences in microstructure between regenerate and control cortical bone. Morphological evaluation suggested a consistent level of anisotropy, possibly related to the distraction vector. After 12 weeks' consolidation, bone created during bone transport distraction osteogenesis was comparable to native bone in microstructure, architecture, and mechanical properties. It is proposed that, after enough time, the properties of the regenerate bone will be identical to that of native bone.

  4. Mandibular Inferior Cortical Bone Thickness on Panoramic Radiographs in Patients using Bisphosphonates

    Science.gov (United States)

    Torres, Sandra R.; Chen, Curtis S. K.; Leroux, Brian G.; Lee, Peggy P.; Hollender, Lars G.; Lloid, Michelle; Drew, Shane Patrick; Schubert, Mark M.

    2015-01-01

    Objective To detect dimensional changes in the mandibular cortical bone associated with bisphosphonate (BP) use and to correlate the measurements of the cortical bone with the cumulative dose of BP therapy. Methods Mandibular inferior cortical bone thickness (MICBT) was measured under the mental foramen from panoramic radiographs of subjects using BP with and without bisphosphonate related osteonecrosis of the jaws (BRONJ) and controls. Results The highest mean MICBT was observed in BRONJ subjects 6.81 (± 1.35 mm), when compared to subjects using BP 5.44 (± 1.09 mm) and controls 4.79 (± 0.85 mm; p<0.01). The mean MICBT of BRONJ subjects was significantly higher than that of subjects using BP without BRONJ. There was a correlation between MICBT and cumulative dose of zolendronate. Conclusion The MICBT on panoramic radiograph is a potentially useful tool for the detection of dimensional changes associated with BP therapy. PMID:25864820

  5. Modalities for Visualization of Cortical Bone Remodeling: The Past, Present, and Future.

    Science.gov (United States)

    Harrison, Kimberly D; Cooper, David M L

    2015-01-01

    Bone's ability to respond to load-related phenomena and repair microdamage is achieved through the remodeling process, which renews bone by activating groups of cells known as basic multicellular units (BMUs). The products of BMUs, secondary osteons, have been extensively studied via classic two-dimensional techniques, which have provided a wealth of information on how histomorphology relates to skeletal structure and function. Remodeling is critical in maintaining healthy bone tissue; however, in osteoporotic bone, imbalanced resorption results in increased bone fragility and fracture. With increasing life expectancy, such degenerative bone diseases are a growing concern. The three-dimensional (3D) morphology of BMUs and their correlation to function, however, are not well-characterized and little is known about the specific mechanisms that initiate and regulate their activity within cortical bone. We believe a key limitation has been the lack of 3D information about BMU morphology and activity. Thus, this paper reviews methodologies for 3D investigation of cortical bone remodeling and, specifically, structures associated with BMU activity (resorption spaces) and the structures they create (secondary osteons), spanning from histology to modern ex vivo imaging modalities, culminating with the growing potential of in vivo imaging. This collection of papers focuses on the theme of "putting the 'why' back into bone architecture." Remodeling is one of two mechanisms "how" bone structure is dynamically modified and thus an improved 3D understanding of this fundamental process is crucial to ultimately understanding the "why."

  6. Response of cortical bone to antiresorptive treatment

    DEFF Research Database (Denmark)

    Hyldstrup, Lars; Jørgensen, J T; Sørensen, T K;

    2001-01-01

    A total of 113 postmenopausal women (69 controls, 33 using hormone replacement therapy (HRT), and 11 using bisphosphonate) were evaluated twice over 2 years with a new noninvasive, radiogrammetry-based technique called digital X-ray radiogrammetry (DXR) and conventional bone densitometry of the s...... treatment regimens used in the prevention of osteoporosis....

  7. Mesenchymal stem cells from cortical bone demonstrate increased clonal incidence, potency, and developmental capacity compared to their bone marrow–derived counterparts

    Directory of Open Access Journals (Sweden)

    Daniel Blashki

    2016-08-01

    Full Text Available In this study, we show that matrix dense cortical bone is the more potent compartment of bone than bone marrow as a stromal source for mesenchymal stem cells as isolated from adult rats. Lineage-depleted cortical bone-mesenchymal stem cells demonstrated >150-fold enrichment of colony forming unit–fibroblasts per cell incidence. compared to lineage-depleted bone marrow-mesenchymal stem cells, corresponding to a 70-fold increase in absolute recovered colony forming unit–fibroblasts. The composite phenotype Lin−/CD45−/CD31−/VLA-1+/Thy-1+ enriched for clonogenic mesenchymal stem cells solely from cortical bone–derived cells from which 70% of clones spontaneously differentiated into all lineages of bone, cartilage, and adipose. Both populations generated vascularized bone tissue within subcutaneous implanted collagen scaffolds; however, cortical bone–derived cells formed significantly more osteoid than bone marrow counterparts, quantified by histology. The data demonstrate that our isolation protocol identifies and validates mesenchymal stem cells with superior clonal, proliferative, and developmental potential from cortical bone compared to the bone marrow niche although marrow persists as the typical source for mesenchymal stem cells both in the literature and current pre-clinical therapies.

  8. Mesenchymal stem cells from cortical bone demonstrate increased clonal incidence, potency, and developmental capacity compared to their bone marrow–derived counterparts

    Science.gov (United States)

    Blashki, Daniel; Murphy, Matthew B; Ferrari, Mauro; Simmons, Paul J; Tasciotti, Ennio

    2016-01-01

    In this study, we show that matrix dense cortical bone is the more potent compartment of bone than bone marrow as a stromal source for mesenchymal stem cells as isolated from adult rats. Lineage-depleted cortical bone-mesenchymal stem cells demonstrated >150-fold enrichment of colony forming unit–fibroblasts per cell incidence. compared to lineage-depleted bone marrow-mesenchymal stem cells, corresponding to a 70-fold increase in absolute recovered colony forming unit–fibroblasts. The composite phenotype Lin−/CD45−/CD31−/VLA-1+/Thy-1+ enriched for clonogenic mesenchymal stem cells solely from cortical bone–derived cells from which 70% of clones spontaneously differentiated into all lineages of bone, cartilage, and adipose. Both populations generated vascularized bone tissue within subcutaneous implanted collagen scaffolds; however, cortical bone–derived cells formed significantly more osteoid than bone marrow counterparts, quantified by histology. The data demonstrate that our isolation protocol identifies and validates mesenchymal stem cells with superior clonal, proliferative, and developmental potential from cortical bone compared to the bone marrow niche although marrow persists as the typical source for mesenchymal stem cells both in the literature and current pre-clinical therapies. PMID:27579159

  9. Multiscale and multimodality computed tomography for cortical bone analysis

    Science.gov (United States)

    Ostertag, A.; Peyrin, F.; Gouttenoire, P. J.; Laredo, J. D.; DeVernejoul, M. C.; Cohen Solal, M.; Chappard, C.

    2016-12-01

    In clinical studies, high resolution peripheral quantitative computed tomography (HR-pQCT) is used to separately evaluate cortical bone and trabecular bone with an isotropic voxel of 82 µm3, and typical cortical parameters are cortical density (D.comp), thickness (Ct.Th), and porosity (Ct.Po). In vitro, micro-computed tomography (micro-CT) is used to explore the internal cortical bone micro-structure with isotropic voxels and high resolution synchrotron radiation (SR); micro-CT is considered the ‘gold standard’. In 16 tibias and 8 femurs, HR-pQCT measurements were compared to conventional micro-CT measurements. To test modality effects, conventional micro-CT measurements were compared to SR micro-CT measurements at 7.5 µm3 SR micro-CT measurements were also tested at different voxel sizes for the femurs, specifically, 7.5 µm3 versus 2.8 µm3. D.comp (r  =  -0.88, p  images provided consistent results compared to those obtained using conventional micro-CT at the distal tibia. D.comp was highly correlated to Po.V/TV because it considers both the micro-porosity (Haversian systems) and macro-porosity (resorption lacunae) of cortical bone. The complexity of canal organization, (including shape, connectivity, and surface) are not fully considered in conventional micro-CT in relation to beam hardening and cone beam reconstruction artifacts. With the exception of Po.V/TV measurements, morphological and topological measurements depend on the characteristics of the x-ray beam, and to a lesser extent, on image resolution.

  10. 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.

  11. Analyzing the anisotropic Hooke's law for children's cortical bone.

    Science.gov (United States)

    Lefèvre, Emmanuelle; Lasaygues, Philippe; Baron, Cécile; Payan, Cédric; Launay, Franck; Follet, Hélène; Pithioux, Martine

    2015-09-01

    Child cortical bone tissue is rarely studied because of the difficulty of obtaining samples. Yet the preparation and ultrasonic characterization of the small samples available, while challenging, is one of the most promising ways of obtaining information on the mechanical behavior of non-pathological children׳s bone. We investigated children׳s cortical bone obtained from chirurgical waste. 22 fibula or femur samples from 21 children (1-18 years old, mean age: 9.7±5.8 years old) were compared to 16 fibula samples from 16 elderly patients (50-95 years old, mean age: 76.2±13.5 years old). Stiffness coefficients were evaluated via an ultrasonic method and anisotropy ratios were calculated as the ratio of C33/C11, C33/C22 and C11/C22. Stiffness coefficients were highly correlated with age in children (R>0.56, p0.5), nor between C44 and C55 (p>0.5). We observe a transverse isotropy with C33>C22=C11>C44C55>C66. For both groups, we found no correlation between age and anisotropy ratios. This study offers the first complete analysis of stiffness coefficients in the three orthogonal bone axes in children, giving some indication of how bone anisotropy is related to age. Future perspectives include studying the effect of the structure and composition of bone on its mechanical behavior. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. Modalities for visualization of cortical bone remodeling: the past, present and near future

    Directory of Open Access Journals (Sweden)

    Kimberly Dawn Harrison

    2015-08-01

    Full Text Available Bone’s ability to respond to load-related phenomena and repair microdamage is achieved through the remodeling process which renews bone by activating groups of cells known as Basic Multicellular Units (BMUs. The products of BMUs, secondary osteons, have been extensively studied via classic two-dimensional (2D techniques which have provided a wealth of information on how histomorphology relates to skeletal structure and function. Remodeling is critical in maintaining healthy bone tissue; however, in osteoporotic bone imbalanced resorption results in increased bone fragility and fracture. With increasing life expectancy, such degenerative bone diseases are a growing concern. The three-dimensional (3D morphology of BMUs and their correlation to function, however, are not well characterized and little is known about the specific mechanisms that initiate and regulate their activity within cortical bone. We believe a key limitation has been the lack 3D information about BMU morphology and activity. Thus, this paper reviews methodologies for 3D investigation of cortical bone remodeling and, specifically, structures associated with BMU activity (resorption spaces and the structures they create (secondary osteons, spanning from histology to modern ex vivo imaging modalities, culminating with the growing potential of in vivo imaging. This collection of papers focuses on the theme of putting the why back into bone archytecture. Remodeling is one of two mechanisms how bone structure is dynamically modified and thus an improved 3D understanding of this fundamental process is crucial to ultimately understanding the why.

  13. Comparative study between cortical bone graft versus bone dust for reconstruction of cranial burr holes.

    Science.gov (United States)

    Worm, Paulo V; Ferreira, Nelson P; Faria, Mario B; Ferreira, Marcelo P; Kraemer, Jorge L; Collares, Marcus V M

    2010-12-22

    As a consequence of the progressive evolution of neurosurgical techniques, there has been increasing concern with the esthetic aspects of burr holes. Therefore, the objective of this study was to compare the use of cortical bone graft and bone dust for correcting cranial deformities caused by neurosurgical trephines. Twenty-three patients were enrolled for cranial burr hole reconstruction with a 1-year follow-up. A total of 108 burr holes were treated; 36 burr holes were reconstructed with autogenous cortical bone discs (33.3%), and the remaining 72 with autogenous wet bone powder (66.6%). A trephine was specifically designed to produce this coin-shaped bone plug of 14 mm in diameter, which fit perfectly over the burr holes. The reconstructions were studied 12 months after the surgical procedure, using three-dimensional quantitative computed tomography. Additionally, general and plastic surgeons blinded for the study evaluated the cosmetic results of those areas, attributing scores from 0 to 10. The mean bone densities were 987.95 ± 186.83 Hounsfield units (HU) for bone fragment and 473.55 ± 220.34 HU for bone dust (P holes because of their lower degree of bone resorption and, consequently, better cosmetic results. The lack of donor site morbidity associated with procedural low cost qualifies the cortical autograft as the first choice for correcting cranial defects created by neurosurgical trephines.

  14. Cancellous and cortical bone imaging by reflected tomography.

    Science.gov (United States)

    Lasaygues, P; Lefebvre, J P

    2001-01-01

    This paper deals with the inverse scattering problem observed when ultrasonic waves are used to analyze biological media. The objective is to image cancellous and cortical bone by ultrasonic reflected tomography (URT). Because strong contrast and high absorbance bodies such as bones cannot be imaged at usual ultrasonic high frequencies (> 1 MHz), we adapted for low-frequency URT (Papoulis deconvolution). This resolution enhancement for human porous vertebrae and human and animal femur showed that high-resolution images can be obtained with low-frequency URT.

  15. Genetic algorithms-based inversion of multimode guided waves for cortical bone characterization

    Science.gov (United States)

    Bochud, N.; Vallet, Q.; Bala, Y.; Follet, H.; Minonzio, J.-G.; Laugier, P.

    2016-10-01

    Recent progress in quantitative ultrasound has exploited the multimode waveguide response of long bones. Measurements of the guided modes, along with suitable waveguide modeling, have the potential to infer strength-related factors such as stiffness (mainly determined by cortical porosity) and cortical thickness. However, the development of such model-based approaches is challenging, in particular because of the multiparametric nature of the inverse problem. Current estimation methods in the bone field rely on a number of assumptions for pairing the incomplete experimental data with the theoretical guided modes (e.g. semi-automatic selection and classification of the data). The availability of an alternative inversion scheme that is user-independent is highly desirable. Thus, this paper introduces an efficient inversion method based on genetic algorithms using multimode guided waves, in which the mode-order is kept blind. Prior to its evaluation on bone, our proposal is validated using laboratory-controlled measurements on isotropic plates and bone-mimicking phantoms. The results show that the model parameters (i.e. cortical thickness and porosity) estimated from measurements on a few ex vivo human radii are in good agreement with the reference values derived from x-ray micro-computed tomography. Further, the cortical thickness estimated from in vivo measurements at the third from the distal end of the radius is in good agreement with the values delivered by site-matched high-resolution x-ray peripheral computed tomography.

  16. Automatic Detection of Cortical Bones Haversian Osteonal Boundaries

    Directory of Open Access Journals (Sweden)

    Ilige Hage

    2015-10-01

    Full Text Available This work aims to automatically detect cement lines in decalcified cortical bone sections stained with H&E. Employed is a methodology developed previously by the authors and proven to successfully count and disambiguate the micro-architectural features (namely Haversian canals, canaliculi, and osteocyte lacunae present in the secondary osteons/Haversian system (osteon of cortical bone. This methodology combines methods typically considered separately, namely pulse coupled neural networks (PCNN, particle swarm optimization (PSO, and adaptive threshold (AT. In lieu of human bone, slides (at 20× magnification from bovid cortical bone are used in this study as proxy of human bone. Having been characterized, features with same orientation are used to detect the cement line viewed as the next coaxial layer adjacent to the outermost lamella of the osteon. Employed for this purpose are three attributes for each and every micro-sized feature identified in the osteon lamellar system: (1 orientation, (2 size (ellipse perimeter and (3 Euler number (a topological measure. From a training image, automated parameters for the PCNN network are obtained by forming fitness functions extracted from these attributes. It is found that a 3-way combination of these features attributes yields good representations of the overall osteon boundary (cement line. Near-unity values of classical metrics of quality (precision, sensitivity, specificity, accuracy, and dice suggest that the segments obtained automatically by the optimized artificial intelligent methodology are of high fidelity as compared with manual tracing. For bench marking, cement lines segmented by k-means did not fare as well. An analysis based on the modified Hausdorff distance (MHD of the segmented cement lines also testified to the quality of the detected cement lines vis-a-vis the k-means method.

  17. Repair of microdamage in osteonal cortical bone adjacent to bone screw.

    Directory of Open Access Journals (Sweden)

    Lei Wang

    Full Text Available Up to date, little is known about the repair mode of microdamage in osteonal cortical bone resulting from bone screw implantation. In this study, self-tapping titanium cortical bone screws were inserted into the tibial diaphyses of 24 adult male rabbits. The animals were sacrificed at 1 day, 2 weeks, 1 month and 2 months after surgery. Histomorphometric measurement and confocal microscopy were performed on basic fuchsin stained bone sections to examine the morphological characteristics of microdamage, bone resorption activity and spatial relationship between microdamage and bone resorption. Diffuse and linear cracks were coexisted in peri-screw bone. Intracortical bone resorption was significantly increased 2 weeks after screw installation and reach to the maximum at 1 month. There was no significant difference in bone resorption between 1-month and 2-months groups. Microdamage was significantly decreased within 1 month after surgery. Bone resorption was predisposed to occur in the region of <100 µm from the bone-screw interface, where had extensive diffuse damage mixed with linear cracks. Different patterns of resorption cavities appeared in peri-screw bone. These data suggest that 1 the complex microdamage composed of diffuse damage and linear cracks is a strong stimulator for initiating targeted bone remodeling; 2 bone resorption activities taking place on the surfaces of differently oriented Haversian and Volkmann canals work in a team for the repair of extensive microdamage; 3 targeted bone remodeling is a short-term reaction to microdamage and thereby it may not be able to remove all microdamage resulting from bone screw insertion.

  18. Cortical potentials associated with voluntary mandibular movements.

    Science.gov (United States)

    Yoshida, K; Kaji, R; Hamano, T; Kohara, N; Kimura, J; Shibasaki, H; Iizuka, T

    2000-07-01

    Movement-related cortical potentials (MRCPs) are negative potentials over the scalp, which gradually increase prior to voluntary movements, and might be applied to elucidate the cortical efferent function of the mandibular movements. We compared the MRCPs accompanying various mandibular movements to study the motor control mechanism underlying these movements. Electroencephalograms (EEGs) were recorded from 11 electrodes placed over the scalp (F3, Fz, F4, T3, C3, Cz, C4, T4, P3, Pz, and P4), according to the International 10-20 System, and electromyograms (EMGs) were obtained from surface electrodes over the masseter muscle and the anterior belly of the digastric muscle. Ten healthy subjects were requested to make brisk and self-paced mandibular movements in 4 different directions (mouth-opening and -closing, and left and right lateral movements). We obtained MRCPs by averaging the EEG, using the visually determined EMG onset as a trigger signal. In all the movements, a slowly increasing, bilaterally widespread negativity starting 1.5 to 2.0 sec before the EMG onset (Bereitschaftspotential, or BP proper) was observed, with the maximum over the vertex region. The negative slope (NS') occurred about 300 to 700 msec before the EMG onset. The cortical maps of BP/NS' (BP and NS' combined), immediately prior to the mouth-opening and closing, showed a symmetrical distribution, whereas that for the lateral movements showed a tendency of predominance over the hemisphere ipsilateral to the direction of the movement. BP/NS' amplitudes at the onset of movement differed significantly or tended to do so between open, close, and lateral movements, suggesting that MRCP recordings may thus provide a means to explore the role of the cerebral cortex in the control of mandibular movements.

  19. 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

  20. WNT16 influences bone mineral density, cortical bone thickness, bone strength, and osteoporotic fracture risk.

    Directory of Open Access Journals (Sweden)

    Hou-Feng Zheng

    2012-07-01

    Full Text Available We aimed to identify genetic variants associated with cortical bone thickness (CBT and bone mineral density (BMD by performing two separate genome-wide association study (GWAS meta-analyses for CBT in 3 cohorts comprising 5,878 European subjects and for BMD in 5 cohorts comprising 5,672 individuals. We then assessed selected single-nucleotide polymorphisms (SNPs for osteoporotic fracture in 2,023 cases and 3,740 controls. Association with CBT and forearm BMD was tested for ∼2.5 million SNPs in each cohort separately, and results were meta-analyzed using fixed effect meta-analysis. We identified a missense SNP (Thr>Ile; rs2707466 located in the WNT16 gene (7q31, associated with CBT (effect size of -0.11 standard deviations [SD] per C allele, P = 6.2 × 10(-9. This SNP, as well as another nonsynonymous SNP rs2908004 (Gly>Arg, also had genome-wide significant association with forearm BMD (-0.14 SD per C allele, P = 2.3 × 10(-12, and -0.16 SD per G allele, P = 1.2 × 10(-15, respectively. Four genome-wide significant SNPs arising from BMD meta-analysis were tested for association with forearm fracture. SNP rs7776725 in FAM3C, a gene adjacent to WNT16, was associated with a genome-wide significant increased risk of forearm fracture (OR = 1.33, P = 7.3 × 10(-9, with genome-wide suggestive signals from the two missense variants in WNT16 (rs2908004: OR = 1.22, P = 4.9 × 10(-6 and rs2707466: OR = 1.22, P = 7.2 × 10(-6. We next generated a homozygous mouse with targeted disruption of Wnt16. Female Wnt16(-/- mice had 27% (P<0.001 thinner cortical bones at the femur midshaft, and bone strength measures were reduced between 43%-61% (6.5 × 10(-13bone strength, and risk of fracture.

  1. Tensile mechanical properties of swine cortical mandibular bone.

    Directory of Open Access Journals (Sweden)

    Tamar Brosh

    Full Text Available Temporary orthodontic mini implants serve as anchorage devices in orthodontic treatments. Often, they are inserted in the jaw bones, between the roots of the teeth. The stability of the mini implants within the bone is one of the major factors affecting their success and, consequently, that of the orthodontic treatment. Bone mechanical properties are important for implant stability. The aim of this study was to determine the tensile properties of the alveolar and basal mandible bones in a swine model. The diametral compression test was employed to study the properties in two orthogonal directions: mesio-distal and occluso-gingival. Small cylindrical cortical bone specimens (2.6 mm diameter, 1.5 mm thickness were obtained from 7 mandibles using a trephine drill. The sites included different locations (anterior and posterior and aspects (buccal and lingual for a total of 16 specimens from each mandible. The load-displacement curves were continuously monitored while loading half of the specimens in the oclluso-gingival direction and half in the mesio-distal direction. The stiffness was calculated from the linear portion of the curve. The mesio-distal direction was 31% stiffer than the occluso-gingival direction. The basal bone was 40% stiffer than the alveolar bone. The posterior zone was 46% stiffer than the anterior zone. The lingual aspect was stiffer than the buccal aspect. Although bone specimens do not behave as brittle materials, the diametral compression test can be adequately used for determining tensile behavior when only small bone specimens can be obtained. In conclusion, to obtain maximal orthodontic mini implant stability, the force components on the implants should be oriented mostly in the mesio-distal direction.

  2. Comparative study between cortical bone graft versus bone dust for reconstruction of cranial burr holes

    OpenAIRE

    Worm, Paulo Valdeci; Ferreira,Nelson Pires; Faria, Mário de Barros; Ferreira, Marcelo Paglioli; Kraemer,Jorge Luiz; Collares, Marcus Vinicius Martins

    2010-01-01

    Background: As a consequence of the progressive evolution of neurosurgical techniques, there has been increasing concern with the esthetic aspects of burr holes. Therefore, the objective of this study was to compare the use of cortical bone graft and bone dust for correcting cranial deformities caused by neurosurgical trephines. Methods: Twenty-three patients were enrolled for cranial burr hole reconstruction with a 1-year follow-up. A total of 108 burr holes were treated; 36 burr holes were ...

  3. Magnetization transfer contrast imaging in bovine and human cortical bone applying an ultrashort echo time sequence at 3 Tesla.

    Science.gov (United States)

    Springer, Fabian; Martirosian, Petros; Machann, Jürgen; Schwenzer, Nina F; Claussen, Claus D; Schick, Fritz

    2009-05-01

    Magnetization transfer (MT) contrast imaging reveals interactions between free water molecules and macromolecules in a variety of tissues. The introduction of ultrashort echo time (UTE) sequences to clinical whole-body MR scanners expands the possibility of MT imaging to tissues with extremely fast signal decay such as cortical bone. The aim of this study was to investigate the MT effect of bovine cortical bone in vitro on a 3 Tesla whole-body MR unit. A 3D-UTE sequence with a rectangular-shaped on-resonant excitation pulse and a Gaussian-shaped off-resonant saturation pulse for MT preparation was applied. The flip angle and off-resonance frequency of the MT pulse was systematically varied. Measurements on various samples of bovine cortical bone, agar gel, aqueous manganese chloride solutions, and solid polymeric materials (polyurethane) were performed, followed by preliminary applications on human tibial bone in vivo. Direct on-resonant saturation effects of the MT prepulses were calculated numerically by means of Bloch's equations. Corrected for direct saturation effects dry and fresh bovine cortical bone showed "true" MTR values of 0.26 and 0.21, respectively. In vivo data were obtained from three healthy subjects and showed MTR values of 0.30 +/- 0.08. In vivo studies into MT of cortical bone might have the potential to give new insights in musculoskeletal pathologies.

  4. Two-wave behavior under various conditions of transition area from cancellous bone to cortical bone.

    Science.gov (United States)

    Nagatani, Yoshiki; Mizuno, Katsunori; Matsukawa, Mami

    2014-07-01

    The two-wave phenomenon, the wave separation of a single ultrasonic pulse in cancellous bone, is expected to be a useful tool for the diagnosis of osteoporosis. However, because actual bone has a complicated structure, precise studies on the effect of transition conditions between cortical and cancellous parts are required. This study investigated how the transition condition influenced the two-wave generation using three-dimensional X-ray CT images of an equine radius and a three-dimensional simulation technique. As a result, any changes in the boundary between cortical part and trabecular part, which gives the actual complex structure of bone, did not eliminate the generation of either the primary wave or the secondary wave at least in the condition of clear trabecular alignment. The results led us to the possibility of using the two-wave phenomenon in a diagnostic system for osteoporosis in cases of a complex boundary.

  5. Automated classification of mandibular cortical bone on dental panoramic radiographs for early detection of osteoporosis

    Science.gov (United States)

    Horiba, Kazuki; Muramatsu, Chisako; Hayashi, Tatsuro; Fukui, Tatsumasa; Hara, Takeshi; Katsumata, Akitoshi; Fujita, Hiroshi

    2015-03-01

    Findings on dental panoramic radiographs (DPRs) have shown that mandibular cortical index (MCI) based on the morphology of mandibular inferior cortex was significantly correlated with osteoporosis. MCI on DPRs can be categorized into one of three groups and has the high potential for identifying patients with osteoporosis. However, most DPRs are used only for diagnosing dental conditions by dentists in their routine clinical work. Moreover, MCI is not generally quantified but assessed subjectively. In this study, we investigated a computer-aided diagnosis (CAD) system that automatically classifies mandibular cortical bone for detection of osteoporotic patients at early stage. First, an inferior border of mandibular bone was detected by use of an active contour method. Second, regions of interest including the cortical bone are extracted and analyzed for its thickness and roughness. Finally, support vector machine (SVM) differentiate cases into three MCI categories by features including the thickness and roughness. Ninety eight DPRs were used to evaluate our proposed scheme. The number of cases classified to Class I, II, and III by a dental radiologist are 56, 25 and 17 cases, respectively. Experimental result based on the leave-one-out cross-validation evaluation showed that the sensitivities for the classes I, II, and III were 94.6%, 57.7% and 94.1%, respectively. Distribution of the groups in the feature space indicates a possibility of MCI quantification by the proposed method. Therefore, our scheme has a potential in identifying osteoporotic patients at an early stage.

  6. Effect of specimen geometry on tensile strength of cortical bone.

    Science.gov (United States)

    Feng, Liang; Jasiuk, Iwona

    2010-11-01

    We investigate the effect of specimen geometry on the ultimate tensile strength of cortical bone measured by a tensile test. This article is motivated by the fact that there is no clear consensus in the literature on a suitable specimen shape for cortical bone testing. We consider three commonly used tensile test specimen shapes: strip, dumbbell with sharp junctions, and dumbbell with rounded junctions. We conduct this study computationally, using a finite element method, and experimentally by testing porcine femurs. Our results show that local stress concentration factors in the specimen lead to reduced values in the measured tensile strength. The higher the stress concentrations are, the lower is the measured strength. We find that the strip specimens are not a good choice due to high stress concentrations. For the same reason, dumbbell specimens with sharp junctions between the grip and gage sections should also be avoided. The dumbbell shaped tensile test specimens with an arc transition and a maximized radius of fillet are a better choice because such geometry lowers stress concentrations.

  7. Aging and Fracture of Human Cortical Bone and Tooth Dentin

    Energy Technology Data Exchange (ETDEWEB)

    Ager, Joel; Koester, Kurt J.; Ager III, Joel W.; Ritchie, Robert O.

    2008-05-07

    Mineralized tissues, such as bone and tooth dentin, serve as structural materials in the human body and, as such, have evolved to resist fracture. In assessing their quantitative fracture resistance or toughness, it is important to distinguish between intrinsic toughening mechanisms which function ahead of the crack tip, such as plasticity in metals, and extrinsic mechanisms which function primarily behind the tip, such as crack bridging in ceramics. Bone and dentin derive their resistance to fracture principally from extrinsic toughening mechanisms which have their origins in the hierarchical microstructure of these mineralized tissues. Experimentally, quantification of these toughening mechanisms requires a crack-growth resistance approach, which can be achieved by measuring the crack-driving force, e.g., the stress intensity, as a function of crack extension ("R-curve approach"). Here this methodology is used to study of the effect of aging on the fracture properties of human cortical bone and human dentin in order to discern the microstructural origins of toughness in these materials.

  8. Long bone histology of the subterranean rodent Bathyergus suillus (Bathyergidae): ontogenetic pattern of cortical bone thickening.

    Science.gov (United States)

    Montoya-Sanhueza, Germán; Chinsamy, Anusuya

    2017-02-01

    Patterns of bone development in mammals are best known from terrestrial and cursorial groups, but there is a considerable gap in our understanding of how specializations for life underground affect bone growth and development. Likewise, studies of bone microstructure in wild populations are still scarce, and they often include few individuals and tend to be focused on adults. For these reasons, the processes generating bone microstructural variation at intra- and interspecific levels are not fully understood. This study comprehensively examines the bone microstructure of an extant population of Cape dune molerats, Bathyergus suillus (Bathyergidae), the largest subterranean mammal endemic to the Western Cape of South Africa. The aim of this study is to investigate the postnatal bone growth of B. suillus using undecalcified histological sections (n = 197) of the femur, humerus, tibia-fibula, ulna and radius, including males and females belonging to different ontogenetic and reproductive stages (n = 42). Qualitative histological features demonstrate a wide histodiversity with thickening of the cortex mainly resulting from endosteal and periosteal bone depositions, whilst there is scarce endosteal resorption and remodeling throughout ontogeny. This imbalanced bone modeling allows the tissues deposited during ontogeny to remain relatively intact, thus preserving an excellent record of growth. The distribution of the different bone tissues observed in the cortex depends on ontogenetic status, anatomical features (e.g. muscle attachment structures) and location on the bone (e.g. anterior or lateral). The type of bone microstructure and modeling is discussed in relation to digging behavior, reproduction and physiology of this species. This study is the first histological assessment describing the process of cortical thickening in long bones of a fossorial mammal.

  9. Scanning electron microscopy of human cortical bone failure surfaces.

    Science.gov (United States)

    Braidotti, P; Branca, F P; Stagni, L

    1997-02-01

    Undecalcified samples extracted from human femoral shafts are fractured by bending and the fracture surfaces are examined with a scanning electron microscope (SEM). The investigation is performed on both dry and wet (hydrated with a saline solution) specimens. SEM micrographs show patterns in many respects similar to those observed in fractography studies of laminated fiber-reinforced synthetic composites. In particular, dry and wet samples behave like brittle and ductile matrix laminates, respectively. An analysis carried out on the basis of the mechanisms that dominate the fracture process of laminates shows that a reasonable cortical bone model is that of a laminated composite material whose matrix is composed of extracellular noncollagenous calcified proteins, and the reinforcement is constituted by the calcified collagen fiber system.

  10. Cancellous Screws Are Biomechanically Superior to Cortical Screws in Metaphyseal Bone.

    Science.gov (United States)

    Wang, Tim; Boone, Christopher; Behn, Anthony W; Ledesma, Justin B; Bishop, Julius A

    2016-09-01

    Cancellous screws are designed to optimize fixation in metaphyseal bone environments; however, certain clinical situations may require the substitution of cortical screws for use in cancellous bone, such as anatomic constraints, fragment size, or available instrumentation. This study compares the biomechanical properties of commercially available cortical and cancellous screw designs in a synthetic model representing various bone densities. Commercially available, fully threaded, 4.0-mm outer-diameter cortical and cancellous screws were tested in terms of pullout strength and maximum insertion torque in standard-density and osteoporotic cancellous bone models. Pullout strength and maximum insertion torque were both found to be greater for cancellous screws than cortical screws in all synthetic densities tested. The magnitude of difference in pullout strength between cortical and cancellous screws increased with decreasing synthetic bone density. Screw displacement prior to failure and total energy absorbed during pullout strength testing were also significantly greater for cancellous screws in osteoporotic models. Stiffness was greater for cancellous screws in standard and osteoporotic models. Cancellous screws have biomechanical advantages over cortical screws when used in metaphyseal bone, implying the ability to both achieve greater compression and resist displacement at the screw-plate interface. Surgeons should preferentially use cancellous over cortical screws in metaphyseal environments where cortical bone is insufficient for fixation. [Orthopedics.2016; 39(5):e828-e832.].

  11. Mechanical strain, induced noninvasively in the high-frequency domain, is anabolic to cancellous bone, but not cortical bone.

    Science.gov (United States)

    Rubin, C; Turner, A S; Mallinckrodt, C; Jerome, C; McLeod, K; Bain, S

    2002-03-01

    Departing from the premise that it is the large-amplitude signals inherent to intense functional activity that define bone morphology, we propose that it is the far lower magnitude, high-frequency mechanical signals that continually barrage the skeleton during longer term activities such as standing, which regulate skeletal architecture. To examine this hypothesis, we proposed that brief exposure to slight elevations in these endogenous mechanical signals would suffice to increase bone mass in those bones subject to the stimulus. This was tested by exposing the hind limbs of adult female sheep (n = 9) to 20 min/day of low-level (0.3g), high-frequency (30 Hz) mechanical signals, sufficient to induce a peak of approximately 5 microstrain (micro epsilon) in the tibia. Following euthanasia, peripheral quantitative computed tomography (pQCT) was used to segregate the cortical shell from the trabecular envelope of the proximal femur, revealing a 34.2% increase in bone density in the experimental animals as compared with controls (p = 0.01). Histomorphometric examination of the femur supported these density measurements, with bone volume per total volume increasing by 32% (p = 0.04). This density increase was achieved by two separate strategies: trabecular spacing decreased by 36.1% (p = 0.02), whereas trabecular number increased by 45.6% (p = 0.01), indicating the formation of cancellous bone de novo. There were no significant differences in the radii of animals subject to the stimulus, indicating that the adaptive response was local rather than systemic. The anabolic potential of the signal was evident only in trabecular bone, and there were no differences, as measured by any assay, in the cortical bone. These data suggest that subtle mechanical signals generated during predominant activities such as posture may be potent determinants of skeletal morphology. Given that these strain levels are three orders of magnitude below strains that can damage bone tissue, we

  12. 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.

  13. Comparative cortical bone thickness between the long bones of humans and five common non-human mammal taxa.

    Science.gov (United States)

    Croker, Sarah L; Reed, Warren; Donlon, Denise

    2016-03-01

    The task of identifying fragments of long bone shafts as human or non-human is difficult but necessary, for both forensic and archaeological cases, and a fast simple method is particularly useful. Previous literature suggests there may be differences in the thickness of the cortical bone between these two groups, but this has not been tested thoroughly. The aim of this study was not only to test this suggestion, but also to provide data that could be of practical assistance for future comparisons. The major limb bones (humerus, radius, femur and tibia) of 50 Caucasoid adult skeletons of known age and sex were radiographed, along with corresponding skeletal elements from sheep, pigs, cattle, large dogs and kangaroos. Measurements were taken from the radiographs at five points along the bone shaft, of shaft diameter, cortical bone thickness, and a cortical thickness index (sum of cortices divided by shaft diameter) in both anteroposterior and mediolateral orientations. Each variable for actual cortical bone thickness as well as cortical thickness indices were compared between the human group (split by sex) and each of the non-human groups in turn, using Student's t-tests. Results showed that while significant differences did exist between the human groups and many of the non-human groups, these were not all in the same direction. That is, some variables in the human groups were significantly greater than, and others were significantly less than, the corresponding variable in the non-human groups, depending on the particular non-human group, sex of the human group, or variable under comparison. This was the case for measurements of both actual cortical bone thickness and cortical thickness index. Therefore, for bone shaft fragments for which the skeletal element is unknown, the overlap in cortical bone thickness between different areas of different bones is too great to allow identification using this method alone. However, by providing extensive cortical bone

  14. 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.

  15. Calcium phosphate cement augmentation of cancellous bone screws can compensate for the absence of cortical fixation.

    Science.gov (United States)

    Stadelmann, Vincent A; Bretton, Elise; Terrier, Alexandre; Procter, Philip; Pioletti, Dominique P

    2010-11-16

    An obvious means to improve the fixation of a cancellous bone screw is to augment the surrounding bone with cement. Previous studies have shown that bone augmentation with Calcium Phosphate (CaP) cement significantly improves screw fixation. Nevertheless, quantitative data about the optimal distribution of CaP cement is not available. The present study aims to show the effect of cement distribution on the screw fixation strength for various cortical thicknesses and to determine the conditions at which cement augmentation can compensate for the absence of cortical fixation in osteoporotic bone. In this study, artificial bone materials were used to mimic osteoporotic cancellous bone and cortical bone of varying thickness. These bone constructs were used to test the fixation strength of cancellous bone screws in different cortical thicknesses and different cement augmentation depths. The cement distribution was measured with microCT. The maximum pullout force was measured experimentally. The microCT analysis revealed a pseudo-conic shape distribution of the cement around the screws. While the maximum pullout strength of the screws in the artificial bone only was 30±7N, it could increase up to approximately 1000N under optimal conditions. Cement augmentation significantly increased pullout force in all cases. The effect of cortical thickness on pullout force was reduced with increased cement augmentation depth. Indeed, cement augmentation without cortical fixation increased pullout forces over that of screws without cement augmentation but with cortical fixation. Since cement augmentation significantly increased pullout force in all cases, we conclude that the loss of cortical fixation can be compensated by cement augmentation.

  16. In Vivo Assessment of Elasticity of Child Rib Cortical Bone Using Quantitative Computed Tomography

    Directory of Open Access Journals (Sweden)

    Y. Zhu

    2017-01-01

    Full Text Available Elasticity of the child rib cortical bone is poorly known due to the difficulties in obtaining specimens to perform conventional tests. It was shown on the femoral cortical bone that elasticity is strongly correlated with density for both children and adults through a unique relationship. Thus, it is assumed that the relationships between the elasticity and density of adult rib cortical bones could be expanded to include that of children. This study estimated in vivo the elasticity of the child rib cortical bone using quantitative computed tomography (QCT. Twenty-eight children (from 1 to 18 y.o. were considered. Calibrated QCT images were prescribed for various thoracic pathologies. The Hounsfield units were converted to bone mineral density (BMD. A relationship between the BMD and the elasticity of the rib cortical bone was applied to estimate the elasticity of children’s ribs in vivo. The estimated elasticity increases with growth (7.1 ± 2.5 GPa at 1 y.o. up to 11.6 ± 1.9 GPa at 18 y.o.. This data is in agreement with the few previous values obtained using direct measurements. This methodology paves the way for in vivo assessment of the elasticity of the child cortical bone based on calibrated QCT images.

  17. The Hounsfield value for cortical bone geometry in the proximal humerus - an in vitro study

    Energy Technology Data Exchange (ETDEWEB)

    Lim Fat, Daren; Kennedy, Jim; Galvin, Rose; O' Brien, Fergal; Mc Grath, Frank; Mullett, Hannan [Royal College of Surgeons in Ireland, Investigations Carried Out at Anatomy Lab, Dublin (Ireland)

    2012-05-15

    Fractures of the proximal humerus represent a major osteoporotic burden. Recent developments in CT imaging have emphasized the importance of cortical bone thickness distribution in the prevention and management of fragility fractures. We aimed to experimentally define the CT density of cortical bone in the proximal humerus for building cortical geometry maps. With ethical approval, we used ten fresh-frozen human proximal humeri. These were stripped of all soft tissue and high-resolution CT images were then taken. The humeral heads were then subsequently resected to allow access to the metaphyseal area. Using curettes, cancellous bone was removed down to hard cortical bone. Another set of CT images of the reamed specimen was then taken. Using CT imaging software and a CAD interface, we then compared cortical contours at different CT density thresholds to the reference inner cortical contour of our reamed specimens. Working with 3D model representations of these cortical maps, we were able to accurately make distance comparison analyses based on different CT thresholds. We could compute a single closest value at 700 HU. No difference was found in the HU-based contours generated along the 500-900 HU pixels (p = 1.000). The contours were significantly different from those generated at 300, 400, 1,000, and 1,100 HU. A Hounsfield range of 500-900 HU can accurately depict cortical bone geometry in the proximal humerus. Thresholding outside this range leads to statistically significant inaccuracies. Our results concur with a similar range reported in the literature for the proximal femur. Knowledge of regional variations in cortical bone thickness has direct implications for basic science studies on osteoporosis and its treatment, but is also important for the orthopedic surgeon since our decision for treatment options is often guided by local bone quality. (orig.)

  18. In vitro study of adhesive polymethylmethacrylate bone cement bonding to cortical bone in maxillofacial surgery.

    Science.gov (United States)

    Smeets, Ralf; Marx, Rudolf; Kolk, Andreas; Said-Yekta, Sareh; Grosjean, Maurice B; Stoll, Christian; Tinschert, Joachim; Wirtz, Dieter C; Riediger, Dieter; Endres, Kira

    2010-12-01

    In the treatment of midface fractures, the fragments are immobilized using screws and plates for osteosynthesis until reunion has occurred. This method involves drilling holes for the insertion of the screws, which can be associated with additional fracturing of the corresponding bone owing to the complex architecture and thin layers of facial bone. To alleviate this problem, new adhesive techniques for fixing the plates for osteosynthesis have been investigated, mitigating the detrimental effects of screw hole drilling. In the present experimental study, the strength of this adhesive bond and its resistance to hydrolysis were investigated. To determine the adhesive bonding strength, a tension test was implemented. Osteosynthesis plates with screw holes 1.3 mm in diameter were fixed to cortical bone samples of bovine femur using ultraviolet (UV) light-curing polymethylmethacrylate bone cement. To facilitate bonding, the surface of the bone was conditioned with an amphiphilic bonding agent before cementing. UV light curing was implemented using either a conventional UV unit, such as is used in dentistry, or with a specialized UV unit with a limited emission spectrum but high luminosity. Reference control samples were prepared without application of the bone bonding agent. After this procedure, the samples were stored for 1 to 7 days at 37°C submerged in 0.9% saline solution before being subjected to the tension test. Without the bone bonding agent, the bonding strength was 0.2 MPa. The primary average bonding strength at day 0 was 8.5 MPa when cured with the conventional UV unit and 14 MPa for the samples cured with the specialized UV unit. An almost constant average bond strength of 8 and 16 MPa was noted for all samples stored up to 7 days after curing with the conventional and specialized UV unit, respectively. With the development of a new bone bonding agent, a method is now available to promote the bonding between the hydrophilic bone surface and the

  19. Post-traumatic transient cortical blindness in a child with occipital bone fracture.

    Science.gov (United States)

    Ng, Rachel H C

    2016-12-01

    Cortical blindness as sequelae of trauma has been reported in literature but mostly in the setting of occipital cortex or visual tract damages. We present a case of transient cortical blindness in a child following a closed head injury with a non-displaced occipital bone fracture and underlying occipital lobe contusion. We discuss the pathophysiology behind Post-traumatic transient cortical blindness, relevant investigations, and current management.

  20. OPTICAL DENSITY OF CORTICAL BONE MATRIX IS DIMINISHED IN EXPERIMENTALLY INDUCED OSTEOPOROSIS

    Directory of Open Access Journals (Sweden)

    Jovan Janić

    2016-06-01

    Full Text Available Osteoporosis is characterized by low bone mineral density (BMD and abnormalities in bone structural and material properties, with unexplained low trauma fractures. The aim of the present study was to quantify the optical density of cortical bone matrix in rats with experimentally induced osteoporosis by ovariectomy. The experimental group was divided in two equal subgroups, the first sacrificed in the third month after ovariectomy and second sacrificed in the fifth month after ovariectomy. After decalcification, on routinely stained histopathologic sections optical density (OD, standard deviation of OD, mode OD, minimal and maximal OD of cortical bone matrix were estimated. Mean optical density and mode optical density of cortical bone were statistically higher in the control than in the experimental group (p<0.05. Maximal optical density of cortical bone was significantly lower in rats three months after ovariectomy than in other groups. Obtained results indicate that in experimentally induced osteoporosis the optical density of cortical bone matrix is diminished, similarly to low bone mineral density.

  1. An Experimental Study of Radiographic Density of Alveolar Bone and Cortical Thickness of Mandible by Osteoporosis

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Byeong Do [Dept. of Oral and Maxillofacial Radiology, School of Dentistry, Wonkwang University, Iksan (Korea, Republic of)

    2000-12-15

    To evaluate the effect of the systemic osteoporosis on radiographic density of alveolar bone and cortical thickness of mandible. The bone mineral density values of lumbar and femur were measured by dual-energy X-ray absorptiometry and T scores of lumbar, femur were obtained respectively. Radiographic densities of alveolar bones and panorama mandibular index (PMI, represents as cortical thickness) were analysed statistically according to age and T score variavles. The radiographic density of alveolar bone of maxillary molar showed significant difference by age and femur T group. That of mandibular molar showed significant difference between femur T group. Panorama mandibular index showed significant difference between age groups. The radiographic density of alvealar bones was more dependent on age femur T than lumbar T. Cortical thickness of mandible was correlated with increasing age.

  2. Assessing temperature changes in cortical bone using variable flip-angle ultrashort echo-time MRI

    Science.gov (United States)

    Han, Misung; Scott, Serena J.; Ozhinsky, Eugene; Salgaonakar, Vasant A.; Jones, Peter D.; Larson, Peder E. Z.; Diederich, Chris J.; Rieke, Viola; Krug, Roland

    2017-03-01

    MR-guided high-intensity focused ultrasound ablation is a promising, noninvasive method for treatment of bone tumors and palliation of pain. During thermal therapy, temperature mapping is necessary to ensure proper heat deposition in targeted tumors as well as to prevent unnecessary heating in surrounding tissues. Conventional MR thermometry exploits the proton resonant frequency shift of water protons, which normally requires a long echo time; therefore, this method is not appropriate for cortical bone due to its short T2* relaxation time. This work demonstrates that ultrashort echo-time MRI can characterize T1 changes in cortical bone caused by temperature changes. Ex vivo experiments were performed to heat diaphysis segments of bovine femurs with an interstitial ultrasound applicator. The T1 increase in the heated parts of cortical bone was observed. The temerature dependence of T1 in cortical born was also assessed by heating bovine bone samples in a temperature-controlled water bath. T1 mapping of cortical bone enabled by ultrashort echo-time MRI might allow for more accurate characterization of thermal dose during treatment of bone tumors.

  3. Ovariectomy-induced changes in aged beagles : histomorphometry of rib cortical bone.

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, A. K.; Bhattacharyya, M. H.; Miller, S.; Sacco-Gibson, N.; Center for Mechanistic Biology and Biotechnology; Univ. of Utah; Procter & Gamble Pharmaceuticals

    1998-03-01

    Bone loss associated with estrogen depletion is well documented in cancellous bone but less well characterized in cortical bone. The effects of ovariectomy on the aged beagle skeleton were studied by histomorphometric analysis of the cortical bone in sequential rib biopsies. Biopsies were taken from each ovariectomized or sham-operated dog at the time of surgery and at 1, 4, and 8.5 months after surgery. Just prior to each postoperative biopsy, tetracycline, calcein, and xylenol orange, respectively, were administered by a fluorochrome labeling procedure (2d-10d-2d) to provide markers of bone formation. Analysis of sequential rib biopsies provided a means to follow the ovariectomy response over time and to compare each animal against its own baseline. Though ovariectomy did not influence histomorphometric indices at 1 month after surgery, a transient increase in cortical bone formation occurred thereafter, with a sixfold increase over that of sham-operated dogs at 4 months (P < 0.001) and a return to near control levels at 8.5 months. Cortical porosity increased by the fourth month after ovariectomy and remained high at 8.5 months. These data demonstrate for the first time that rib cortical bone is a responsive site for the effects of ovariectomy in aged female dogs.

  4. Propagation of time-reversed Lamb waves in bovine cortical bone in vitro.

    Science.gov (United States)

    Lee, Kang Il; Yoon, Suk Wang

    2015-01-01

    The present study aims to investigate the propagation of time-reversed Lamb waves in bovine cortical bone in vitro. The time-reversed Lamb waves were successfully launched at 200 kHz in 18 bovine tibiae through a time reversal process of Lamb waves. The group velocities of the time-reversed Lamb waves in the bovine tibiae were measured using the axial transmission technique. They showed a significant correlation with the cortical thickness and tended to follow the theoretical group velocity of the lowest order antisymmetrical Lamb wave fairly well, consistent with the behavior of the slow guided wave in long cortical bones.

  5. A grape-enriched diet increases bone calcium retention and cortical bone properties in ovariectomized rats.

    Science.gov (United States)

    Hohman, Emily E; Weaver, Connie M

    2015-02-01

    Grapes and their associated phytochemicals have been investigated for beneficial effects on cardiovascular health, cancer prevention, and other chronic diseases, but the effect of grape consumption on bone health has not been fully determined. We previously found short-term benefits of grape products on reducing bone turnover in ovariectomized rats. The objective of this study was to determine the long-term benefits of a grape-enriched diet on bone in ovariectomized rats. Rats were ovariectomized at 3 mo of age and were administered a single dose of (45)Ca to prelabel bones at 4 mo of age. After a 1-mo equilibration period, baseline urinary (45)Ca excretion was determined. Rats (n = 22/group) were then randomly assigned to a modified AIN93M diet containing 25% freeze-dried grape powder or to a control diet for 8 wk. Urinary (45)Ca excretion was monitored throughout the study to determine changes in bone (45)Ca retention. Calcium balance was assessed after 1 and 8 wk of consuming the experimental diets, and a calcium kinetic study was performed at 8 wk. After 8 wk, femurs were collected for micro-computed tomographic imaging, 3-point bending, and reference point indentation. Rats fed the grape-enriched diet had 44% greater net bone calcium retention than did rats fed the control diet. There were no differences in calcium balance due to diet at either week 1 or week 8, but there was a significant increase in net calcium absorption (10.6%) and retention (5.7%) from week 1 to week 8 in the grape-enriched diet group only. Grape-enriched diet-fed rats had 3% greater cortical thickness and 11% greater breaking strength. There were no differences in femur bone mineral density, trabecular microarchitecture, or reference point indentation variables due to diet. This study of ovariectomized rats indicates that the consumption of grape products may improve calcium utilization and suppress bone turnover, resulting in improvements in bone quality. © 2015 American Society for

  6. Midline lumbar fusion using cortical bone trajectory screws. Preliminary report

    Directory of Open Access Journals (Sweden)

    Mateusz Bielecki

    2016-09-01

    Full Text Available Introduction : Midline lumbar fusion (MIDLF using cortical bone trajectory is an alternative method of transpedicular spinal fusion for degenerative disease. The new entry points’ location and screwdriving direction allow the approach-related morbidity to be reduced. Aim: To present our preliminary experience with the MIDLF technique on the first 5 patients with lumbar degenerative disease and with follow-up of at least 6 months. Material and methods: Retrospective analysis was performed on the first 5 patients with foraminal (4 or central (1 stenosis operated on between December 2014 and February 2015. Three patients were fused at L4–L5 and two at the L5–S1 level. Results: No intra- or post-operative complications occurred with this approach. An improvement regarding the leading symptom in the early postoperative period (sciatica 4/4, claudication 1/1 was achieved in all patients. The mean improvements in the visual analogue scale for low back and leg pain were 2.2 and 4.8 respectively. The mean Oswestry Disability Index scores were 52% (range: 16–82% before surgery and 33% (range: 12–56% at 3-month follow-up (mean improvement 19%. At the most recent follow-up, 4 patients reported the maintenance of the satisfactory result. The early standing and follow-up X-rays showed satisfactory screw placement in all patients. Conclusions : In our initial experience, the MIDLF technique seems to be an encouraging alternative to traditional transpedicular trajectory screws when short level lumbar fusion is needed. Nevertheless, longer observations on larger groups of patients are needed to reliably evaluate the safety of the method and the sustainability of the results.

  7. Speech identification and cortical potentials in individuals with auditory neuropathy

    Directory of Open Access Journals (Sweden)

    Vanaja CS

    2008-03-01

    Full Text Available Abstract Background Present study investigated the relationship between speech identification scores in quiet and parameters of cortical potentials (latency of P1, N1, and P2; and amplitude of N1/P2 in individuals with auditory neuropathy. Methods Ten individuals with auditory neuropathy (five males and five females and ten individuals with normal hearing in the age range of 12 to 39 yr participated in the study. Speech identification ability was assessed for bi-syllabic words and cortical potentials were recorded for click stimuli. Results Results revealed that in individuals with auditory neuropathy, speech identification scores were significantly poorer than that of individuals with normal hearing. Individuals with auditory neuropathy were further classified into two groups, Good Performers and Poor Performers based on their speech identification scores. It was observed that the mean amplitude of N1/P2 of Poor Performers was significantly lower than that of Good Performers and those with normal hearing. There was no significant effect of group on the latency of the peaks. Speech identification scores showed a good correlation with the amplitude of cortical potentials (N1/P2 complex but did not show a significant correlation with the latency of cortical potentials. Conclusion Results of the present study suggests that measuring the cortical potentials may offer a means for predicting perceptual skills in individuals with auditory neuropathy.

  8. 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.

  9. Cortical bone development under the growth plate is regulated by mechanical load transfer.

    NARCIS (Netherlands)

    Tanck, E.J.M.; Hannink, G.J.; Ruimerman, R.; Buma, P.; Burger, E.H.; Huiskes, R.

    2006-01-01

    Longitudinal growth of long bones takes place at the growth plates. The growth plate produces new bone trabeculae, which are later resorbed or merged into the cortical shell. This process implies transition of trabecular metaphyseal sections into diaphyseal sections. We hypothesize that the developm

  10. Effect of micromorphology of cortical bone tissue on crack propagation under dynamic loading

    Science.gov (United States)

    Wang, Mayao; Gao, Xing; Abdel-Wahab, Adel; Li, Simin; Zimmermann, Elizabeth A.; Riedel, Christoph; Busse, Björn; Silberschmidt, Vadim V.

    2015-09-01

    Structural integrity of bone tissue plays an important role in daily activities of humans. However, traumatic incidents such as sports injuries, collisions and falls can cause bone fracture, servere pain and mobility loss. In addition, ageing and degenerative bone diseases such as osteoporosis can increase the risk of fracture [1]. As a composite-like material, a cortical bone tissue is capable of tolerating moderate fracture/cracks without complete failure. The key to this is its heterogeneously distributed microstructural constituents providing both intrinsic and extrinsic toughening mechanisms. At micro-scale level, cortical bone can be considered as a four-phase composite material consisting of osteons, Haversian canals, cement lines and interstitial matrix. These microstructural constituents can directly affect local distributions of stresses and strains, and, hence, crack initiation and propagation. Therefore, understanding the effect of micromorphology of cortical bone on crack initiation and propagation, especially under dynamic loading regimes is of great importance for fracture risk evaluation. In this study, random microstructures of a cortical bone tissue were modelled with finite elements for four groups: healthy (control), young age, osteoporosis and bisphosphonate-treated, based on osteonal morphometric parameters measured from microscopic images for these groups. The developed models were loaded under the same dynamic loading conditions, representing a direct impact incident, resulting in progressive crack propagation. An extended finite-element method (X-FEM) was implemented to realize solution-dependent crack propagation within the microstructured cortical bone tissues. The obtained simulation results demonstrate significant differences due to micromorphology of cortical bone, in terms of crack propagation characteristics for different groups, with the young group showing highest fracture resistance and the senior group the lowest.

  11. Effect of micromorphology of cortical bone tissue on crack propagation under dynamic loading

    Directory of Open Access Journals (Sweden)

    Wang Mayao

    2015-01-01

    Full Text Available Structural integrity of bone tissue plays an important role in daily activities of humans. However, traumatic incidents such as sports injuries, collisions and falls can cause bone fracture, servere pain and mobility loss. In addition, ageing and degenerative bone diseases such as osteoporosis can increase the risk of fracture [1]. As a composite-like material, a cortical bone tissue is capable of tolerating moderate fracture/cracks without complete failure. The key to this is its heterogeneously distributed microstructural constituents providing both intrinsic and extrinsic toughening mechanisms. At micro-scale level, cortical bone can be considered as a four-phase composite material consisting of osteons, Haversian canals, cement lines and interstitial matrix. These microstructural constituents can directly affect local distributions of stresses and strains, and, hence, crack initiation and propagation. Therefore, understanding the effect of micromorphology of cortical bone on crack initiation and propagation, especially under dynamic loading regimes is of great importance for fracture risk evaluation. In this study, random microstructures of a cortical bone tissue were modelled with finite elements for four groups: healthy (control, young age, osteoporosis and bisphosphonate-treated, based on osteonal morphometric parameters measured from microscopic images for these groups. The developed models were loaded under the same dynamic loading conditions, representing a direct impact incident, resulting in progressive crack propagation. An extended finite-element method (X-FEM was implemented to realize solution-dependent crack propagation within the microstructured cortical bone tissues. The obtained simulation results demonstrate significant differences due to micromorphology of cortical bone, in terms of crack propagation characteristics for different groups, with the young group showing highest fracture resistance and the senior group the

  12. A Retrospective Study on Indian Population to evaluate Cortical Bone Thickness in Maxilla and Mandible using Computed Tomography Images

    Directory of Open Access Journals (Sweden)

    Jeegar Ketan Vakil

    2014-01-01

    Conclusion: Mini-implants have gained considerable popularity due to their low cost, effectiveness, clinical management and stability. Among the factors related to microimplant stability, bone density and cortical bone thickness appear to be critical for successful placement. This study will provide knowledge of cortical bone thickness in various areas which can guide the clinicians in selecting the placement site.

  13. Effect of Cortical Bone Thickness on Detection of Intraosseous Lesions by Ultrasonography

    Directory of Open Access Journals (Sweden)

    Sadaf Adibi

    2015-01-01

    Full Text Available Background. Usefulness of ultrasound (US in detection of intrabony lesions has been showed. A cortical bone perforation or a very thin and intact cortical bone is prerequisite for this purpose. Objective. The current in vitro study was aimed at measuring the cut-off thickness of the overlying cortical bone which allows ultrasonic assessment of bony defects. Materials and Methods. 20 bovine scapula blocks were obtained. Samples were numbered from 1 to 20. In each sample, 5 artificial lesions were made. The lesions were made in order to increase the overlying bone thickness, from 0.1 mm in the first sample to 2 mm in the last one (with 0.1 mm interval. After that, the samples underwent ultrasound examinations by two practicing radiologists. Results. All five lesions in samples numbered 1 to 11 were detected as hypoechoic area. Cortical bone thickness more than 1.1 mm resulted in a failure in the detection of central lesions. Conclusion. We can conclude that neither bony perforation nor very thin cortical bones are needed to consider US to be an effective imaging technique in the evaluation of bony lesion.

  14. Temperature Values Variability in Piezoelectric Implant Site Preparation: Differences between Cortical and Corticocancellous Bovine Bone

    Directory of Open Access Journals (Sweden)

    Luca Lamazza

    2016-01-01

    Full Text Available Purpose. Various parameters can influence temperature rise and detection during implant site preparation. The aim of this study is to investigate local temperature values in cortical and corticocancellous bovine bone during early stages of piezoelectric implant site preparation. Materials and Methods. 20 osteotomies were performed using a diamond tip (IM1s, Mectron Medical Technology, Carasco, Italy on two different types of bovine bone samples, cortical and corticocancellous, respectively. A standardized protocol was designed to provide constant working conditions. Temperatures were measured in real time at a fixed position by a fiber optic thermometer. Results. Significantly higher drilling time (154.90 sec versus 99.00 sec; p<0.0001 and temperatures (39.26°C versus 34.73°C; p=0.043 were observed in the cortical group compared to the corticocancellous group. A remarkable variability of results characterized the corticocancellous blocks as compared to the blocks of pure cortical bone. Conclusion. Bone samples can influence heat generation during in vitro implant site preparation. When compared to cortical bone, corticocancellous samples present more variability in temperature values. Even controlling most experimental factors, the impact of bone samples still remains one of the main causes of temperature variability.

  15. Influence of bone microstructure on the mechanical properties of skull cortical bone - A combined experimental and computational approach.

    Science.gov (United States)

    Boruah, Sourabh; Subit, Damien L; Paskoff, Glenn R; Shender, Barry S; Crandall, Jeff R; Salzar, Robert S

    2017-01-01

    The strength and compliance of the dense cortical layers of the human skull have been examined since the beginning of the 20th century with the wide range in the observed mechanical properties attributed to natural biological variance. Since this variance may be explained by the difference in structural arrangement of bone tissue, micro-computed tomography (µCT) was used in conjunction with mechanical testing to study the relationship between the microstructure of human skull cortical coupons and their mechanical response. Ninety-seven bone samples were machined from the cortical tables of the calvaria of ten fresh post mortem human surrogates and tested in dynamic tension until failure. A linear response between stress and strain was observed until close to failure, which occurred at 0.6% strain on average. The effective modulus of elasticity for the coupons was 12.01 ± 3.28GPa. Porosity of the test specimens, determined from µCT, could explain only 51% of the variation of their effective elastic modulus. Finite element (FE) models of the tested specimens built from µCT images indicated that modeling the microstructural arrangement of the bone, in addition to the porosity, led to a marginal improvement of the coefficient of determination to 54%. Modulus for skull cortical bone for an element size of 50µm was estimated to be 19GPa at an average. Unlike the load bearing bones of the body, almost half of the variance in the mechanical properties of cortical bone from the skull may be attributed to differences at the sub-osteon (< 50µm) level. ANOVA tests indicated that effective failure stress and strain varied significantly between the frontal and parietal bones, while the bone phase modulus was different for the superior and inferior aspects of the calvarium. The micro FE models did not indicate any anisotropy attributable to the pores observable under µCT.

  16. Drilling in cortical bone: a finite element model and experimental investigations.

    Science.gov (United States)

    Lughmani, Waqas A; Bouazza-Marouf, Kaddour; Ashcroft, Ian

    2015-02-01

    Bone drilling is an essential part of many orthopaedic surgery procedures, including those for internal fixation and for attaching prosthetics. Estimation and control of bone drilling forces are critical to prevent drill-bit breakthrough, excessive heat generation, and mechanical damage to the bone. An experimental and computational study of drilling in cortical bone has been conducted. A 3D finite element (FE) model for prediction of thrust forces experienced during bone drilling has been developed. The model incorporates the dynamic characteristics involved in the process along with geometrical considerations. An elastic-plastic material model is used to predict the behaviour of cortical bone during drilling. The average critical thrust forces and torques obtained using FE analysis are found to be in good agreement with the experimental results.

  17. Specifications for machining the bovine cortical bone in relation to its microstructure.

    Science.gov (United States)

    Sugita, Naohiko; Mitsuishi, Mamoru

    2009-12-11

    Until date, many devices have been developed for cutting human bones during orthopedic surgeries. However, bones are anisotropic material, and their machining characteristics depend on the tool feed direction. In this study, microcutting of the bovine cortical bone is performed and its structure observed under a microscope. Furthermore, the formation of cutting chips and measurement of the cutting force during bone machining are dynamically observed while considering the anisotropy of bone tissue. In particular, the fracture of secondary osteons and crack propagation in bones are observed and analyzed. The results indicate that when the cut depth exceeds 20mum and is greater than the interval of concentric lamellae, cracks are formed together with chips. A new method for bone machining is proposed. This method is based on the characteristics of crack propagation in bones and is expected to produce low mechanical stress and realize highly efficient and precise machining of living tissues such as bones.

  18. Calcifying tendinitis of the rotator cuff with cortical bone erosion.

    Science.gov (United States)

    Chan, Roxanne; Kim, David H; Millett, Peter J; Weissman, Barbara N

    2004-10-01

    Calcifying tendinitis occurs most commonly in the rotator cuff tendons, particularly involving the supraspinatus tendon insertion, and is often asymptomatic. Cortical erosion secondary to calcifying tendinitis has been reported in multiple locations, including in the rotator cuff tendons. We present a pathologically proven case of symptomatic calcifying tendinitis involving the infraspinatus tendon with cortical erosion with correlative radiographic, CT, and MR findings. The importance of considering this diagnosis when evaluating lytic lesions of the humerus and the imaging differential diagnosis of calcifying tendinitis and cortical erosion are discussed.

  19. Calcifying tendinitis of the rotator cuff with cortical bone erosion

    Energy Technology Data Exchange (ETDEWEB)

    Chan, Roxanne; Kim, David H.; Millett, Peter J. [Harvard Medical School, Brigham and Women' s Hospital, Boston, Massachusetts (United States); Weissman, Barbara N. [Harvard Medical School, Brigham and Women' s Hospital, Boston, Massachusetts (United States); Brigham and Women' s Hospital, Department of Radiology, Musculoskeletal Division, Boston (United States)

    2004-10-01

    Calcifying tendinitis occurs most commonly in the rotator cuff tendons, particularly involving the supraspinatus tendon insertion, and is often asymptomatic. Cortical erosion secondary to calcifying tendinitis has been reported in multiple locations, including in the rotator cuff tendons. We present a pathologically proven case of symptomatic calcifying tendinitis involving the infraspinatus tendon with cortical erosion with correlative radiographic, CT, and MR findings. The importance of considering this diagnosis when evaluating lytic lesions of the humerus and the imaging differential diagnosis of calcifying tendinitis and cortical erosion are discussed. (orig.)

  20. Growth hormone effects on cortical bone dimensions in young adults with childhood-onset growth hormone deficiency

    DEFF Research Database (Denmark)

    Hyldstrup, L; Conway, G S; Racz, K

    2012-01-01

    Growth hormone (GH) treatment in young adults with childhood-onset GH deficiency has beneficial effects on bone mass. The present study shows that cortical bone dimensions also benefit from GH treatment, with endosteal expansion and increased cortical thickness leading to improved bone strength....... INTRODUCTION: In young adults with childhood-onset growth hormone deficiency (CO GHD), GH treatment after final height is reached has been shown to have beneficial effects on spine and hip bone mineral density. The objective of the study was to evaluate the influence of GH on cortical bone dimensions. METHODS......: Patients (n = 160; mean age, 21.2 years; 63% males) with CO GHD were randomised 2:1 to GH or no treatment for 24 months. Cortical bone dimensions were evaluated by digital x-ray radiogrammetry of the metacarpal bones every 6 months. RESULTS: After 24 months, cortical thickness was increased compared...

  1. Mechanistic fracture criteria for the failure of human cortical bone

    Energy Technology Data Exchange (ETDEWEB)

    Nalla, Ravi K.; Kinney, John H.; Ritchie, Robert O.

    2002-12-13

    A mechanistic understanding of fracture in human bone is critical to predicting fracture risk associated with age and disease. Despite extensive work, a mechanistic framework for describing how the underlying microstructure affects the failure mode in bone is lacking.

  2. Regional variability in secondary remodeling within long bone cortices of catarrhine primates: the influence of bone growth history.

    Science.gov (United States)

    McFarlin, Shannon C; Terranova, Carl J; Zihlman, Adrienne L; Enlow, Donald H; Bromage, Timothy G

    2008-09-01

    Secondary intracortical remodeling of bone varies considerably among and within vertebrate skeletons. Although prior research has shed important light on its biomechanical significance, factors accounting for this variability remain poorly understood. We examined regional patterning of secondary osteonal bone in an ontogenetic series of wild-collected primates, at the midshaft femur and humerus of Chlorocebus (Cercopithecus) aethiops (n = 32) and Hylobates lar (n = 28), and the midshaft femur of Pan troglodytes (n = 12). Our major objectives were: 1) to determine whether secondary osteonal bone exhibits significant regional patterning across inner, mid-cortical and outer circumferential cortical rings within cross-sections; and if so, 2) to consider the manner in which this regional patterning may reflect the influence of relative tissue age and other circumstances of bone growth. Using same field-of-view images of 100-microm-thick cross-sections acquired in brightfield and circularly polarized light microscopy, we quantified the percent area of secondary osteonal bone (%HAV) for whole cross-sections and across the three circumferential rings within cross-sections. We expected bone areas with inner and middle rings to exhibit higher %HAV than the outer cortical ring within cross-sections, the latter comprising tissues of more recent depositional history. Observations of primary bone microstructural development provided an additional context in which to evaluate regional patterning of intracortical remodeling. Results demonstrated significant regional variability in %HAV within all skeletal sites. As predicted,%HAV was usually lowest in the outer cortical ring within cross-sections. However, regional patterning across inner vs. mid-cortical rings showed a more variable pattern across taxa, age classes, and skeletal sites examined. Observations of primary bone microstructure revealed that the distribution of endosteally deposited bone had an important influence on

  3. A histological investigation on tissue responses to titanium implants in cortical bone of the rat femur.

    Science.gov (United States)

    Ohtsu, A; Kusakari, H; Maeda, T; Takano, Y

    1997-03-01

    Implant materials are placed under various sites-including cortical bone, spongy bone, and bone marrow-at the same time according to the depth at implantation. Although cortical bone is an important site for the prognosis of implantation, detailed reports on tissue responses to implantation have been meager. The present study aims to reveal tissue responses to pure titanium implantation in rat femoris cortical bone. The rats received titanium bars surgically in their femurs and were sacrificed 1 day to 40 weeks post-implantation. The prepared tissue specimens were processed for light and transmission electron microscopy (TEM). Further histochemical detections were performed. One day post-implantation, empty osteocytic lacunae indicating degeneration of osteocytes were found in pre-existing cortical bone around the implant. Such pre-existing bone was replaced by new bone, but remained in part even 40 weeks post-implantation. Light microscopy showed that direct contact between the implant and new bone was identified 12 weeks post-implantation. Chronological and ultrastructural observation showed that new bone deposition appeared to proceed toward the implant, and that the intervening layer at the interface was derived from the degenerated debris of multinucleated giant cells and/or osteoblasts. Furthermore, it seemed that the width of intervening layer varied in relation to the distance from the blood vessels. The cells showing tartrate resistant acid phosphatase activity possessed cytological features of osteoclasts under TEM; they were frequently observed in perivascular sites near the implants even after osseointegration, suggesting that bone remodeling took place steadily around the implant.

  4. Strontium Ranelate Effect on the Repair of Bone Defects and Molecular Components of the Cortical Bone of Rats.

    Science.gov (United States)

    Rosa, Jucely Aparecida da; Sakane, Kumiko Koibuchi; Santos, Karina Cecília Panelli; Corrêa, Vivian Bradaschia; Arana-Chavez, Victor Elias; Oliveira, Jefferson Xavier de

    2016-01-01

    This study was conducted to evaluate the effects of treatment with strontium ranelate (SR) on the repair of bone defects and molecular components of bones in femurs. Adult female rats (n=27) were subjected to ovariectomy (OVX) or Sham surgery. Thirty days after surgery, a defect was made in the femur and the animals were then divided into three groups: OVX, SHAM and OVX+SR. Euthanasia was performed four weeks after the bone defect surgery. Repair in bone defect was assessed by computed microtomography (μCT) and chemical composition of cortical bone was analyzed by Fourier transform infrared (FTIR) spectroscopy and energy dispersive X-ray spectroscopy (EDS). The trabecular thickness (Tb.Th) of the newly formed bone in the OVX+SR group was significantly higher than that for the OVX group. The collagen maturity in the OVX+SR group was smaller than in the other two groups. In this group, a significant increase in the amount of strontium (Sr) and a decrease in the amount of calcium (Ca) embedded to bone tissue were also observed. Systemic treatment with SR improved microarchitecture of the newly formed bone inside the defect, but decreased cross-linking of mature collagen in cortical bone.

  5. Cortical Auditory Evoked Potentials in Unsuccessful Cochlear Implant Users

    Science.gov (United States)

    Munivrana, Boska; Mildner, Vesna

    2013-01-01

    In some cochlear implant users, success is not achieved in spite of optimal clinical factors (including age at implantation, duration of rehabilitation and post-implant hearing level), which may be attributed to disorders at higher levels of the auditory pathway. We used cortical auditory evoked potentials to investigate the ability to perceive…

  6. One Size Fits All? Slow Cortical Potentials Neurofeedback: A Review

    Science.gov (United States)

    Mayer, Kerstin; Wyckoff, Sarah N.; Strehl, Ute

    2013-01-01

    Objective: The intent of this manuscript was to review all published studies on slow cortical potentials (SCP) neurofeedback for the treatment of ADHD, with emphasis on neurophysiological rationale, study design, protocol, outcomes, and limitations. Method: For review, PubMed, MEDLINE, ERIC, and Google Scholar searches identified six studies and…

  7. Cortical Auditory Evoked Potentials in Unsuccessful Cochlear Implant Users

    Science.gov (United States)

    Munivrana, Boska; Mildner, Vesna

    2013-01-01

    In some cochlear implant users, success is not achieved in spite of optimal clinical factors (including age at implantation, duration of rehabilitation and post-implant hearing level), which may be attributed to disorders at higher levels of the auditory pathway. We used cortical auditory evoked potentials to investigate the ability to perceive…

  8. Biomedical titanium alloys with Young’s moduli close to that of cortical bone

    Science.gov (United States)

    Niinomi, Mitsuo; Liu, Yi; Nakai, Masaki; Liu, Huihong; Li, Hua

    2016-01-01

    Biomedical titanium alloys with Young’s moduli close to that of cortical bone, i.e., low Young’s modulus titanium alloys, are receiving extensive attentions because of their potential in preventing stress shielding, which usually leads to bone resorption and poor bone remodeling, when implants made of their alloys are used. They are generally β-type titanium alloys composed of non-toxic and allergy-free elements such as Ti–29Nb–13Ta–4.6Zr referred to as TNTZ, which is highly expected to be used as a biomaterial for implants replacing failed hard tissue. Furthermore, to satisfy the demands from both patients and surgeons, i.e., a low Young’s modulus of the whole implant and a high Young’s modulus of the deformed part of implant, titanium alloys with changeable Young’s modulus, which are also β-type titanium alloys, for instance Ti–12Cr, have been developed. In this review article, by focusing on TNTZ and Ti–12Cr, the biological and mechanical properties of the titanium alloys with low Young’s modulus and changeable Young’s modulus are described. In addition, the titanium alloys with shape memory and superelastic properties were briefly addressed. Surface modifications for tailoring the biological and anti-wear/corrosion performances of the alloys have also been briefly introduced. PMID:27252887

  9. Biomedical titanium alloys with Young's moduli close to that of cortical bone.

    Science.gov (United States)

    Niinomi, Mitsuo; Liu, Yi; Nakai, Masaki; Liu, Huihong; Li, Hua

    2016-09-01

    Biomedical titanium alloys with Young's moduli close to that of cortical bone, i.e., low Young's modulus titanium alloys, are receiving extensive attentions because of their potential in preventing stress shielding, which usually leads to bone resorption and poor bone remodeling, when implants made of their alloys are used. They are generally β-type titanium alloys composed of non-toxic and allergy-free elements such as Ti-29Nb-13Ta-4.6Zr referred to as TNTZ, which is highly expected to be used as a biomaterial for implants replacing failed hard tissue. Furthermore, to satisfy the demands from both patients and surgeons, i.e., a low Young's modulus of the whole implant and a high Young's modulus of the deformed part of implant, titanium alloys with changeable Young's modulus, which are also β-type titanium alloys, for instance Ti-12Cr, have been developed. In this review article, by focusing on TNTZ and Ti-12Cr, the biological and mechanical properties of the titanium alloys with low Young's modulus and changeable Young's modulus are described. In addition, the titanium alloys with shape memory and superelastic properties were briefly addressed. Surface modifications for tailoring the biological and anti-wear/corrosion performances of the alloys have also been briefly introduced.

  10. Early cortical bone healing around loaded titanium implants: a histological study in the rabbit.

    Science.gov (United States)

    Slaets, Elke; Naert, Ignace; Carmeliet, Geert; Duyck, Joke

    2009-02-01

    To identify the role of immediate implant loading on the early phases of the bone healing responses. Implants were placed in rabbit tibial diaphyses and left to heal for 3, 7, 14, 28 or 42 days. Half of the animals received an immediate loading protocol of 2.2 N at 3 Hz for 1800 cycles and 5 days/week, whereas the others served as unloaded controls. Histological assessment was combined with histomorphometrical measurements. At early time-points, an endosteal and periosteal new bone formation was found, while the cortex itself contained damaged osteocytes. At later time-points, new bone formation was also found at the cortical level itself. Differences between groups were found mainly in this new bone formation process, with larger reactions for the endosteal and periosteal bone in the loaded group after 28 and 42 days, respectively. At the end-point of the experiment, bone formation at the cortical level was reduced in the loaded group compared with the control group. These results show that the immediate loading protocol caused no differences in the sequential events leading to osseointegration in cortical bone. However, the processes of new bone formation originating from the endosteum and the periosteum lasted longer compared with the unloaded controls.

  11. Femoral cortical index: an indicator of poor bone quality in patient with hip fracture.

    Science.gov (United States)

    Feola, M; Rao, C; Tempesta, V; Gasbarra, E; Tarantino, U

    2015-10-01

    Osteoporosis is a common disease in elderly, characterized by poor bone quality as a result of alterations affecting trabecular bone. However, recent studies have described also an important role of alterations of cortical bone in the physiopathology of osteoporosis. Although dual-energy X-ray absorptiometry (DXA) is a valid method to assess bone mineral density, in the presence of comorbidities real bone fragility is unable to be evaluated. The number of hip fractures is rising, especially in people over 85 years old. The aim is to evaluate an alternative method so that it can indicate fracture risk, independent of bone mineral density (BMD). Femoral cortical index (FCI) assesses cortical bone stock using femur X-ray. A retrospective study has been conducted on 152 patients with hip fragility fractures. FCI has been calculated on fractured femur and on the opposite side. The presence of comorbidities, osteoporosis risk factors, vitamin D levels, and BMD have been analyzed for each patient. Average values of FCI have been 0.42 for fractured femurs and 0.48 at the opposite side with a statistically significant difference (p = 0.002). Patients with severe hypovitaminosis D had a minor FCI compared to those with moderate deficiency (0.41 vs. 0.46, p hip fractures has been found. FCI could be a useful tool to evaluate bone fragility and to predict fracture risk even in the normal and osteopenic BMD patients.

  12. Human Auditory Processing: Insights from Cortical Event-related Potentials

    Directory of Open Access Journals (Sweden)

    Alexandra P. Key

    2016-04-01

    Full Text Available Human communication and language skills rely heavily on the ability to detect and process auditory inputs. This paper reviews possible applications of the event-related potential (ERP technique to the study of cortical mechanisms supporting human auditory processing, including speech stimuli. Following a brief introduction to the ERP methodology, the remaining sections focus on demonstrating how ERPs can be used in humans to address research questions related to cortical organization, maturation and plasticity, as well as the effects of sensory deprivation, and multisensory interactions. The review is intended to serve as a primer for researchers interested in using ERPs for the study of the human auditory system.

  13. Variations of mechanical property of out circumferential lamellae in cortical bone along the radial by nanoindentation

    Directory of Open Access Journals (Sweden)

    Xingdong Sun

    2016-11-01

    Full Text Available Because the out circumferential lamellae have a special protective effect on the cortical bone, it is very important to understand the variations of the mechanical property of the out circumferential lamellae in cortical bone. For the purpose, the elasticity modulus and hardness of out circumferential lamellae in cortical bone were investigated in two orthogonal planes by nanoindentation, and the comparisons were made for both elasticity modulus and hardness between the two orthogonal planes. From the experiments, the decreasing trend was discovered for elasticity modulus from inside to outside in the transverse plane and ruleless variations tendency was presented in the longitudinal plane. The hardness presented the same variations in two orthogonal planes with elasticity modulus in respective plane. In the same layer, the elasticity modulus in the transverse plane was higher than that in the longitudinal plane, and the difference values between them turned to be smaller. In contrast, the hardness in the longitudinal plane was higher than that in the transverse plane in all the layers. From the heterogeneity and the microstructure of the material, the influence factors were discussed. A soft to hard structure model was put forward, and the coordinating protection mechanism of buffer and support was described. Investigation of variations of mechanical properties of out circumferential lamellae in cortical bone can provide some new understanding in researches of fracture of bone, interface load effect and design of bone graft.

  14. The effects of glucocorticoid on microarchitecture, collagen, mineral and mechanical properties of sheep femur cortical bone

    DEFF Research Database (Denmark)

    Ding, Ming; Danielsen, Carl C; Overgaard, Søren

    mechanical properties in the glucocorticoid-2. In conclusion, 7 months glucocorticoid treatment with malnutrition had significant impact on cortical microarchitecture of sheep femur midshaft. These changes occurred particularly 3 months after the glucocorticoid cessation suggesting a delayed effect......The effects of glucocorticoid on microarchitecture, collagen, mineral and mechanical properties of sheep femur cortical bone – Validation of large animal model for tissue engineering and biomaterial research Ming Ding,1* Carl Christian Danielsen,2 Søren Overgaard1 1Orthopaedic Research Laboratory...

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

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    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

  16. The effects of glucocorticoid on microarchitecture, collagen, mineral and mechanical properties of sheep femur cortical bone

    DEFF Research Database (Denmark)

    Ding, Ming; Danielsen, Carl C; Overgaard, Søren

    2010-01-01

    The effects of glucocorticoid on microarchitecture, collagen, mineral and mechanical properties of sheep femur cortical bone – Validation of large animal model for tissue engineering and biomaterial research Ming Ding,1* Carl Christian Danielsen,2 Søren Overgaard1 1Orthopaedic Research Laboratory...... treatment. Group 3 was left untreated and served as the controls. All sheep received restricted diet with low calcium and phosphorus. At sacrifice, cortical bone samples from the femur midshaft of sheep were harvested, micro-CT scanned and tested in 3 point bending and in tensile. Bone collagen and mineral...... mechanical properties in the glucocorticoid-2. In conclusion, 7 months glucocorticoid treatment with malnutrition had significant impact on cortical microarchitecture of sheep femur midshaft. These changes occurred particularly 3 months after the glucocorticoid cessation suggesting a delayed effect...

  17. 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.

  18. Insulin Resistance Is Associated With Smaller Cortical Bone Size in Nondiabetic Men at the Age of Peak Bone Mass.

    Science.gov (United States)

    Verroken, Charlotte; Zmierczak, Hans-Georg; Goemaere, Stefan; Kaufman, Jean-Marc; Lapauw, Bruno

    2017-06-01

    In type 2 diabetes mellitus, fracture risk is increased despite preserved areal bone mineral density. Although this apparent paradox may in part be explained by insulin resistance affecting bone structure and/or material properties, few studies have investigated the association between insulin resistance and bone geometry. We aimed to explore this association in a cohort of nondiabetic men at the age of peak bone mass. Nine hundred ninety-six nondiabetic men aged 25 to 45 years were recruited in a cross-sectional, population-based sibling pair study at a university research center. Insulin resistance was evaluated using the homeostasis model assessment of insulin resistance (HOMA-IR), with insulin and glucose measured from fasting serum samples. Bone geometry was assessed using peripheral quantitative computed tomography at the distal radius and the radial and tibial shafts. In age-, height-, and weight-adjusted analyses, HOMA-IR was inversely associated with trabecular area at the distal radius and with cortical area, periosteal and endosteal circumference, and polar strength strain index at the radial and tibial shafts (β ≤ -0.13, P insulin-like growth factor 1, or sex steroid levels. In this cohort of nondiabetic men at the age of peak bone mass, insulin resistance is inversely associated with trabecular and cortical bone size. These associations persist after adjustment for body composition, muscle size or function, or sex steroid levels, suggesting an independent effect of insulin resistance on bone geometry.

  19. A preliminary investigation of the dynamic viscoelastic relaxation of bovine cortical bone

    Directory of Open Access Journals (Sweden)

    Loete T.J.C.

    2015-01-01

    Full Text Available A new experimental approach is proposed to characterize the dynamic viscoelastic relaxation behaviour of cortical bone. Theoretical models are presented to show that a linear viscoelastic material, when allowed to relax between two long elastic bars, will produce stress, strain and strain rate histories that contain characteristic features. Furthermore, typical experimental results are presented to show that these characteristic features are observed during split Hopkinson bar tests on bovine cortical bone using a Cone-in-Tube striker. The interpretation of this behaviour in the context of a standard linear viscoelastic model is discussed.

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

    Science.gov (United States)

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

    2014-03-01

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

  1. Nonlinear hierarchical multiscale modeling of cortical bone considering its nanoscale microstructure.

    Science.gov (United States)

    Ghanbari, J; Naghdabadi, R

    2009-07-22

    We have used a hierarchical multiscale modeling scheme for the analysis of cortical bone considering it as a nanocomposite. This scheme consists of definition of two boundary value problems, one for macroscale, and another for microscale. The coupling between these scales is done by using the homogenization technique. At every material point in which the constitutive model is needed, a microscale boundary value problem is defined using a macroscopic kinematical quantity and solved. Using the described scheme, we have studied elastic properties of cortical bone considering its nanoscale microstructural constituents with various mineral volume fractions. Since the microstructure of bone consists of mineral platelet with nanometer size embedded in a protein matrix, it is similar to the microstructure of soft matrix nanocomposites reinforced with hard nanostructures. Considering a representative volume element (RVE) of the microstructure of bone as the microscale problem in our hierarchical multiscale modeling scheme, the global behavior of bone is obtained under various macroscopic loading conditions. This scheme may be suitable for modeling arbitrary bone geometries subjected to a variety of loading conditions. Using the presented method, mechanical properties of cortical bone including elastic moduli and Poisson's ratios in two major directions and shear modulus is obtained for different mineral volume fractions.

  2. The effect of high voltage, high frequency pulsed electric field on slain ovine cortical bone.

    Science.gov (United States)

    Asgarifar, Hajarossadat; Oloyede, Adekunle; Zare, Firuz

    2014-04-01

    High power, high frequency pulsed electric fields known as pulsed power (PP) has been applied recently in biology and medicine. However, little attention has been paid to investigate the application of pulse power in musculoskeletal system and its possible effect on functional behavior and biomechanical properties of bone tissue. This paper presents the first research investigating whether or not PP can be applied safely on bone tissue as a stimuli and what will be the possible effect of these signals on the characteristics of cortical bone by comparing the mechanical properties of this type of bone pre and post expose to PP and in comparison with the control samples. A positive buck-boost converter was applied to generate adjustable high voltage, high frequency pulses (up to 500 V and 10 kHz). The functional behavior of bone in response to pulse power excitation was elucidated by applying compressive loading until failure. The stiffness, failure stress (strength) and the total fracture energy (bone toughness) were determined as a measure of the main bone characteristics. Furthermore, an ultrasonic technique was applied to determine and comprise bone elasticity before and after pulse power stimulation. The elastic property of cortical bone samples appeared to remain unchanged following exposure to pulse power excitation for all three orthogonal directions obtained from ultrasonic technique and similarly from the compression test. Nevertheless, the compressive strength and toughness of bone samples were increased when they were exposed to 66 h of high power pulsed electromagnetic field compared to the control samples. As the toughness and the strength of the cortical bone tissue are directly associated with the quality and integrity of the collagen matrix whereas its stiffness is primarily related to bone mineral content these overall results may address that although, the pulse power stimulation can influence the arrangement or the quality of the collagen network

  3. Postnatal Changes in Humerus Cortical Bone Thickness Reflect the Development of Metabolic Bone Disease in Preterm Infants

    Directory of Open Access Journals (Sweden)

    Shuko Tokuriki

    2016-01-01

    Full Text Available Objective. To use cortical bone thickness (CBT of the humerus to identify risk factors for the development of metabolic bone disease in preterm infants. Methods. Twenty-seven infants born at <32 weeks of gestational age, with a birth weight of <1,500 g, were enrolled. Humeral CBT was measured from chest radiographs at birth and at 27-28, 31-32, and 36–44 weeks of postmenstrual age (PMA. The risk factors for the development of osteomalacia were statistically analyzed. Results. The humeral CBT at 36–44 weeks of PMA was positively correlated with gestational age and birth weight and negatively correlated with the duration of mechanical ventilation. CBT increased with PMA, except in six very early preterm infants in whom it decreased. Based on logistic regression analysis, gestational age and duration of mechanical ventilation were identified as risk factors for cortical bone thinning. Conclusions. Humeral CBT may serve as a radiologic marker of metabolic bone disease at 36–44 weeks of PMA in preterm infants. Cortical bones of extremely preterm infants are fragile, even when age is corrected for term, and require extreme care to lower the risk of fractures.

  4. 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.

  5. 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.

  6. Prostaglandin E2 Increased Rat Cortical Bone Mass When Administered Immediately Following Ovariectomy

    Science.gov (United States)

    Ke, Hua Zhu; Jee, Webster S.S.; Zeng, Qing Qiang; Li, Mei; Lin, Bai Yun

    1993-01-01

    To investigate the effects of ovariectomy and the simultaneous administration of prostaglandin E2 (PGE2) on rat tibial shaft cortical bone histomorphometry, thirty-five 3 month-old female Sprague-Dawley rats were either ovariectomized (OVX), or sham ovariectomy (sham-OVX). The OVX rats were divided into three groups and treated with 0, 1 and 6 mg PGE2/kg/day for 90 days. The double fluorescent labeled undecalcified tibial shaft cross sections (proximal to the tibiofibular junction) of all the subjects were used for histomorphometry analysis. No differences in cross-sectional area and cortical bone area were found between sham-OVX and OVX controls, but OVX increased marrow area, intracortical porosity area and endocortical eroded perimeter. Periosteal and endocortical bone formation rates decreased with aging yet OVX prevented these changes. These OVX-induced increases in marrow area and endocortical eroded perimeter were prevented by 1 mg PGE2/kg/day treatment and added bone to periosteal and endocortical surfaces and to the marrow cavity. At the 6 mg/kg/day dose level, PGE2-treated OVX rats increased total tissue area, cortical bone area, marrow trabmular bone area, minimal cortical width and intracortical porosity area, and decreased marrow area compared to basal, sham-OVX and OVX controls. In addition, periosteal bone formation was elevated in the 6 mg PGE2/kg/day-treated OVX rats compared to OVX controls. Endocortical eroded perimeter increased from basal and sham-OVX control levels, but decreased from OVX control levels in the 6 mg PGE2/kg/day-treated OVX rats. Our study confirmed that ovariectomy does not cause osteopenia in tibial shaft cortical bone in rats, but it does stimulate endocortical bone resorption and enlarges marrow area. The new findings from the present study demonstrate that PGE2 prevents the OVX-induced increases in endocortical bone resorption and marrow area and adds additional bone to periosteal and endocortical surfaces and to marrow

  7. 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.

  8. The effects of glucocorticoid on microarchitecture, collagen, mineral and mechanical properties of sheep femur cortical bone.

    Science.gov (United States)

    Ding, Ming; Danielsen, Carl Christian; Overgaard, Søren

    2012-06-01

    In this study, 18 female skeletally mature sheep were randomly allocated into three groups of six each. Group 1 (glucocorticoid-1) received prednisolone treatment (0.60 mg/kg/day, five times weekly) for 7 months. Group 2 (glucocorticoid-2) received the same treatment regime followed by observation of 3 months without treatment. Group 3 was left untreated and served as controls. All sheep received a restricted diet with low calcium and phosphorus. At sacrifice, cortical bone samples from the femur midshaft of each sheep were harvested, micro-CT scanned and subjected to three-point bending and tensile strength testing. Bone collagen and mineral were determined. Cortical porosity was significantly increased in the glucocorticoid-2 compared with the glucocorticoid-1 and control groups. Apparent density was significantly decreased in the glucocorticoid-2 compared with the glucocorticoid-1 group. Collagen content was significantly increased in the glucocorticoid-2 compared with the glucocorticoid-1 and control groups. Bone mineral content did not differ between the groups. Neither the three-point bending mechanical properties nor the tensile mechanical properties differed significantly between the groups, while there was a trend towards decreasing bending mechanical properties in the glucocorticoid-2 group. In conclusion, 7 months of glucocorticoid treatment with malnutrition had a significant impact on the cortical microarchitecture of the sheep femur midshaft. These observed changes occurred 3 months after glucocorticoid cessation, suggesting a delayed effect of glucocorticoid on cortical bone. Thus, changes in cortical bone beyond cancellous bone might further increase fracture risk in patients treated with glucocorticoids. This model might be used as a glucocorticoid-induced osteoporotic model for orthopaedic biomaterial, joint prosthesis and medical device researches.

  9. Experimental and numerical analysis of Izod impact test of cortical bone tissue

    Science.gov (United States)

    Abdel-Wahab, A. A.; Silberschmidt, V. V.

    2012-05-01

    Bones can only sustain loads until a certain limit, beyond which they fail. Usually, the reasons for bone fracture are traumatic falls, sports injuries, and engagement in transport or industrial accidents. A proper treatment of bones and prevention of their fracture can be supported by in-depth understanding of deformation and fracture behavior of this tissue in such dynamic events. In this paper, a combination of experimental and numerical analysis was carried out in order to comprehend the fracture behavior of cortical bone tissue. Experimental tests were performed to study the transient dynamic behavior of cortical bone tissue under impact bending loading. The variability of absorbed energy for different cortex positions and notch depths was studied using Izod impact tests. Also, Extended Finite-Element Method implemented into the commercial finite-element software Abaqus was used to simulate the crack initiation and growth processes in a cantilever beam of cortical bone exposed to impact loading using the Izod loading scheme. The simulation results show a good agreement with the experimental data.

  10. Non-nuclear-initiated actions of the estrogen receptor protect cortical bone mass.

    Science.gov (United States)

    Bartell, Shoshana M; Han, Li; Kim, Ha-neui; Kim, Sung Hoon; Katzenellenbogen, John A; Katzenellenbogen, Benita S; Chambliss, Ken L; Shaul, Philip W; Roberson, Paula K; Weinstein, Robert S; Jilka, Robert L; Almeida, Maria; Manolagas, Stavros C

    2013-04-01

    Extensive evidence has suggested that at least some of the effects of estrogens on bone are mediated via extranuclear estrogen receptor α signaling. However, definitive proof for this contention and the extent to which such effects may contribute to the overall protective effects of estrogens on bone maintenance have remained elusive. Here, we investigated the ability of a 17β-estradiol (E2) dendrimer conjugate (EDC), incapable of stimulating nuclear-initiated actions of estrogen receptor α, to prevent the effects of ovariectomy (OVX) on the murine skeleton. We report that EDC was as potent as an equimolar dose of E2 in preventing bone loss in the cortical compartment that represents 80% of the entire skeleton, but was ineffective on cancellous bone. In contrast, E2 was effective in both compartments. Consistent with its effect on cortical bone mass, EDC partially prevented the loss of both vertebral and femoral strength. In addition, EDC, as did E2, prevented the OVX-induced increase in osteoclastogenesis, osteoblastogenesis, and oxidative stress. Nonetheless, the OVX-induced decrease in uterine weight was unaltered by EDC but was restored by E2. These results demonstrate that the protection of cortical bone mass by estrogens is mediated, at least in part, via a mechanism that is distinct from the classic mechanism of estrogen action on reproductive organs.

  11. How Tough is Human Cortical Bone? In-Situ Measurements on Realistically Short Cracks

    Energy Technology Data Exchange (ETDEWEB)

    Ritchie, Robert O; Koester, K. J.; Ager III, J. W.; Ritchie, R.O.

    2008-05-10

    Bone is more difficult to break than to split. Although this is well known, and many studies exist on the behavior of long cracks in bone, there is a need for data on the orientation-dependent crack-growth resistance behavior of human cortical bone which accurately assesses its toughness at appropriate size-scales. Here we use in-situ mechanical testing in the scanning electron microscope and x-ray computed tomography to examine how physiologically-pertinent short (<600 mu m) cracks propagate in both the transverse and longitudinal orientations in cortical bone, using both crack-deflection/twist mechanics and nonlinear-elastic fracture mechanics to determine crack-resistance curves. We find that after only 500 mu m of cracking, the driving force for crack propagation was more than five times higher in the transverse (breaking) direction than in the longitudinal (splitting) direction due to major crack deflections/twists principally at cement sheathes. Indeed, our results show that the true transverse toughness of cortical bone is far higher than previously reported. However, the toughness in the longitudinal orientation, where cracks tend to follow the cement lines, is quite low at these small crack sizes; it is only when cracks become several millimeters in length that bridging mechanisms can develop leading to the (larger-crack) toughnesses generally quoted for bone.

  12. Non-invasive predictors of human cortical bone mechanical properties: T(2-discriminated H NMR compared with high resolution X-ray.

    Directory of Open Access Journals (Sweden)

    R Adam Horch

    Full Text Available Recent advancements in magnetic resonance imaging (MRI have enabled clinical imaging of human cortical bone, providing a potentially powerful new means for assessing bone health with molecular-scale sensitivities unavailable to conventional X-ray-based diagnostics. To this end, (1H nuclear magnetic resonance (NMR and high-resolution X-ray signals from human cortical bone samples were correlated with mechanical properties of bone. Results showed that (1H NMR signals were better predictors of yield stress, peak stress, and pre-yield toughness than were the X-ray derived signals. These (1H NMR signals can, in principle, be extracted from clinical MRI, thus offering the potential for improved clinical assessment of fracture risk.

  13. Cortical Interneuron Subtypes Vary in Their Axonal Action Potential Properties

    OpenAIRE

    Casale, Amanda E.; Foust, Amanda J.; Bal, Thierry; McCormick, David A.

    2015-01-01

    The role of interneurons in cortical microcircuits is strongly influenced by their passive and active electrical properties. Although different types of interneurons exhibit unique electrophysiological properties recorded at the soma, it is not yet clear whether these differences are also manifested in other neuronal compartments. To address this question, we have used voltage-sensitive dye to image the propagation of action potentials into the fine collaterals of axons and dendrites in two o...

  14. Experimental Investigations on Microcracks in Vibrational and Conventional Drilling of Cortical Bone

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    Yu Wang

    2013-01-01

    Full Text Available Bone drilling is widely used in orthopedic surgery. Microcracks will be generated in bone drilling, which may cause fatigue damages and stress fractures. Fresh bovine cortical bones were drilled via vibrational and conventional ways. Drilling operations were performed by a dynamic material testing machine, which can provide the vibration while maintaining uniform feed motion. The drill site and bone debris were observed through scanning electron microscope (SEM. The experimental results showed that fewer and shorter micro-cracks were formed in vibrational drilling than those formed in conventional way. And the surface morphology of bone debris from two different drilling ways was also quite different. It is expected that vibrational drilling in orthopedic surgery operation could decrease the microdamage to the bone, which could lower the incidence of stress fracture and contribute to the postoperative recovery.

  15. 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

  16. Using smooth particle hydrodynamics to investigate femoral cortical bone remodelling at the Haversian level.

    Science.gov (United States)

    Fernandez, J W; Das, R; Cleary, P W; Hunter, P J; Thomas, C D L; Clement, J G

    2013-01-01

    In the neck of the femur, about 70% of the strength is contributed by the cortical bone, which is the most highly stressed part of the structure and is the site where failure is almost certainly initiated. A better understanding of cortical bone remodelling mechanisms can help discern changes at this anatomical site, which are essential if an understanding of the mechanisms by which hips weaken and become vulnerable to fracture is to be gained. The aims of this study were to (i) examine a hypothesis that low strain fields arise because of subject-specific Haversian canal distributions causing bone resorption and reduced bone integrity and (ii) introduce the use of a meshless particle-based computational modelling approach SPH to capture bone remodelling features at the level of the Haversian canals. We show that bone remodelling initiated by strain at the Haversian level is highly influenced by the subject-specific pore distribution, bone density, loading and osteocyte density. SPH is shown to be effective at capturing the intricate bone pore shapes that evolved over time.

  17. Measuring metacarpal cortical bone by digital x-ray radiogrammetry: a step forward?

    NARCIS (Netherlands)

    Geusens, PP; Lems, W.F.

    2009-01-01

    Changes in metacarpal cortical bone mineral density (BMD) using digital x-ray radiogrammetry were studied in patients with early rheumatoid arthritis. After 1, 2, and 5 years, large BMD losses were found: -1.7%, -2.8%, and -5.6%, respectively. Elevated erythrocyte sedimentation rate and anti-cyclic

  18. [ANATOMICAL PLATE COMBINED WITH CORTICAL BONE PLATE ALLOGRAFTS FOR TREATMENT OF COMMINUTED FRACTURES OF FEMORAL CONDYLES].

    Science.gov (United States)

    Guo, Zhimin; Gong, Xingxing; Li, Yanwei; Qiu, Xiaochun; Zhang, Meng; Shangguan, Tiancheng; Ao, Qingfang; Liu, Qiang

    2015-01-01

    To summarize the effectiveness of anatomical plate combined with cortical bone plate allografts in the treatment of comminuted fractures of the femoral condyles. Between January 2008 and December 2012, 18 patients with comminuted fractures of the femoral condyles were treated, including 13 males and 5 females with an average age of 45 years (range, 23-65 years). Fractures were caused by traffic accident in 11 cases, by falling from height in 4 cases, and by the other in 3 cases. The locations were the left side in 7 cases and the right side in 11 cases. Of 18 fractures, 12 were open fractures and 6 were closed fractures. The mean time from injury to operation was 6 days (range, 4-15 days). The fixation was performed by anatomical plate combined with cortical bone plate allografts, and autograft bone or allogeneic bone grafting were used. Superficial local skin necrosis occurred in 1 case, and was cured after skin graft, and other incisions achieved primary healing. All patients were followed up 12-36 months (mean, 23 months). X-ray films showed that bone union was achieved within 3-12 months (5.6 months on average). No related complication occurred, such as fixation loosening, refracture, infection, or immunological rejection. According to Merchan et al. criteria for knee joint function evaluation, the results were excellent in 7 cases, good in 9 cases, fair in 1 case, and poor in 1 case at last follow-up; the excellent and good rate was 88.9%. Anatomical plate combined with cortical bone plate allograft fixation is a good method to treat comminuted fractures of the femoral condyles. This method can effectively achieve complete cortical bone on the inside of the femur as well as provide rigid fixation.

  19. Cortical modulation of short-latency TMS-evoked potentials

    Directory of Open Access Journals (Sweden)

    Domenica eVeniero

    2013-01-01

    Full Text Available Transcranial magnetic stimulation - electroencephalogram (TMS-EEG co-registration offers the opportunity to test reactivity of brain areas across distinct conditions through TMS-evoked potentials (TEPs. Several TEPs have been described, their functional meaning being largely unknown. In particular, short-latency potentials peaking at 5 (P5 and 8 (N8 ms after the TMS pulse have been recently described, but because of their huge amplitude, the problem of whether their origin is cortical or not has been opened. To gain information about these components, we employed a protocol that modulates primary motor cortex excitability (MI through an exclusively cortical phenomena: low frequency stimulation of premotor area (PMC. TMS was applied simultaneously with EEG recording from 70 electrodes. Amplitude of TEPs evoked by 200 single-pulses TMS delivered over MI at 110% of resting motor threshold was measured before and after applying 900 TMS conditioning stimuli to left premotor cortex with 1 Hz repetition rate. Single subject analyses showed reduction in TEPs amplitude after PMC conditioning in a sample of participants and increase in TEPs amplitude in two subjects. No effects were found on corticospinal excitability as recorded by motor evoked potentials (MEPs. Furthermore, correlation analysis showed an inverse relation between the effects of the conditioning protocol on P5-N8 complex amplitude and MEPs amplitude. Because the effects of the used protocol have been ascribed to a cortical interaction between premotor area and MI, we suggest that despite the sign of P5-N8 amplitude modulation is not consistent across participant, this modulation could indicate, at least in part, their cortical origin. We conclude that with an accurate experimental procedure early-latency components can be used to evaluate the reactivity of the stimulated cortex.

  20. Extra-nuclear effects of estrogen on cortical bone in males require ERαAF-1

    Science.gov (United States)

    Wu, J; Gustafsson, K L; Windahl, S H; Kim, S H; Katzenellenbogen, J A; Ohlsson, C; Lagerquist, M K

    2017-01-01

    Estradiol (E2) signaling via estrogen receptor alpha (ERα) is important for the male skeleton as demonstrated by ERα inactivation in both mice and man. ERα mediates estrogenic effects not only by translocating to the nucleus and affecting gene transcription but also by extra-nuclear actions e.g., triggering cytoplasmic signaling cascades. ERα contains various domains, and the role of activation function 1 (ERαAF-1) is known to be tissue specific. The aim of this study was to determine the importance of extra-nuclear estrogen effects for the skeleton in males and to determine the role of ERαAF-1 for mediating these effects. Five-month-old male wild-type (WT) and ERαAF-1-inactivated (ERαAF-10) mice were orchidectomized and treated with equimolar doses of 17β-estradiol (E2) or an estrogen dendrimer conjugate (EDC), which is incapable of entering the nucleus and thereby only initiates extra-nuclear ER actions or their corresponding vehicles for 3.5 weeks. As expected, E2 treatment increased cortical thickness and trabecular bone volume per total volume (BV/TV) in WT males. EDC treatment increased cortical thickness in WT males, whereas no effect was detected in trabecular bone. In ERαAF-10 males, E2 treatment increased cortical thickness, but did not affect trabecular bone. Interestingly, the effect of EDC on cortical bone was abolished in ERαAF-10 mice. In conclusion, extra-nuclear estrogen signaling affects cortical bone mass in males, and this effect is dependent on a functional ERαAF-1. Increased knowledge regarding estrogen signaling mechanisms in the regulation of the male skeleton may aid the development of new treatment options for male osteoporosis. PMID:28057769

  1. Female Mice Lacking Estrogen Receptor-α in Hypothalamic Proopiomelanocortin (POMC) Neurons Display Enhanced Estrogenic Response on Cortical Bone Mass.

    Science.gov (United States)

    Farman, H H; Windahl, S H; Westberg, L; Isaksson, H; Egecioglu, E; Schele, E; Ryberg, H; Jansson, J O; Tuukkanen, J; Koskela, A; Xie, S K; Hahner, L; Zehr, J; Clegg, D J; Lagerquist, M K; Ohlsson, C

    2016-08-01

    Estrogens are important regulators of bone mass and their effects are mainly mediated via estrogen receptor (ER)α. Central ERα exerts an inhibitory role on bone mass. ERα is highly expressed in the arcuate (ARC) and the ventromedial (VMN) nuclei in the hypothalamus. To test whether ERα in proopiomelanocortin (POMC) neurons, located in ARC, is involved in the regulation of bone mass, we used mice lacking ERα expression specifically in POMC neurons (POMC-ERα(-/-)). Female POMC-ERα(-/-) and control mice were ovariectomized (OVX) and treated with vehicle or estradiol (0.5 μg/d) for 6 weeks. As expected, estradiol treatment increased the cortical bone thickness in femur, the cortical bone mechanical strength in tibia and the trabecular bone volume fraction in both femur and vertebrae in OVX control mice. Importantly, the estrogenic responses were substantially increased in OVX POMC-ERα(-/-) mice compared with the estrogenic responses in OVX control mice for cortical bone thickness (+126 ± 34%, P mass, ERα was silenced using an adeno-associated viral vector. Silencing of ERα in hypothalamic VMN resulted in unchanged bone mass. In conclusion, mice lacking ERα in POMC neurons display enhanced estrogenic response on cortical bone mass and mechanical strength. We propose that the balance between inhibitory effects of central ERα activity in hypothalamic POMC neurons in ARC and stimulatory peripheral ERα-mediated effects in bone determines cortical bone mass in female mice.

  2. Machining characteristics of the haversian and plexiform components of bovine cortical bone.

    Science.gov (United States)

    Conward, Michael; Samuel, Johnson

    2016-07-01

    This paper investigates the characteristic differences observed while machining the haversian and plexiform components of a bovine cortical femoral bone. To this end micro-milling slotting experiments are performed on both the components by varying both the cutting velocity and the feed-per-tooth values. The scale of machining is chosen specifically to ensure sensitivity to the microstructural variations in the bone. The material properties of the microstructural components and their size-scale relative to the feed-per-tooth values are seen to dictate the failure mechanisms encountered during machining. The cutting force, surface roughness, and tool wear are all uniquely affected by the plexiform and haversian components of the cortical bone. In general, plexiform bone requires a higher cutting force than the haversian bone. While a higher cutting velocity can lower the surface roughness of haversian bone, it typically results in the most surface damage. The cutting force and surface roughness values for both the components show strain rate sensitivity. The tool wear is seen to be the highest while cutting parallel to the lamellar structures seen in the plexiform bone.

  3. TYMPANOPLASTY WITH SEPTAL CARTILAGE AND CORTICAL MASTOID BONE IN CHOLESTEATOMA PATIENTS

    Directory of Open Access Journals (Sweden)

    Biram Singh

    2015-12-01

    Full Text Available OBJECTIVE This study was conducted to find out the ideal graft between septal cartilage and cortical mastoid bone in Farrior’s type 3 tympanoplasty in cholesteatoma patients in terms of hearing improvement, graft status and recurrence rate of the disease after canal wall down mastoidectomy. METHODS This randomized controlled trial was conducted in a tertiary care centre and the procedure and data collections were carried out for one and a half calendar year with effect from September 2007 and each case was followed up for 6 months. The data were entered and calculated statistically using SPSS16 for windows. RESULTS The study shows significant hearing improvement in both the groups. The tympanoplasty type 3 with cortical mastoid bone had air bone gap less than 20dB in 40% of patients. In septal cartilage, tympanoplasty group air bone gap less than 20dB was observed in 36.4%. Retraction of graft developed in 1(2.4% out of 20 patients among cortical mastoid bone tympanoplasty group. Among 22 patients of septal cartilage tympanoplasty type 3, 2(4.8% patients had cartilage resorption and 3(7.1% had graft displacement. Of the total 42 patients, 2(4.8% developed recurrence of the disease. CONCLUSION Cholesteatoma management is controversial. Canal wall down mastoidectomy can reduce the recurrence of disease. The cortical mastoid bone and septal cartilage grafts can provide hearing improvement after tympanoplasty type 3. There is no significant difference in hearing improvement between the two grafts.

  4. The effect of high energy shock waves focused on cortical bone: an in vitro study.

    Science.gov (United States)

    Kaulesar Sukul, D M; Johannes, E J; Pierik, E G; van Eijck, G J; Kristelijn, M J

    1993-01-01

    Extracorporeal shock wave lithotripsy has become an accepted alternative for the management of nephrolithiasis and cholelithiasis. Direct impact of shock waves cause tear and shear forces at transition sites between tissues with divergent acoustic impedances leading to stone fragmentation. The aim of this study was to determine whether shock waves can cause cortical bone damage at all and, if so, what the relationship is, if any, between the energy density of the shock waves, the number of shock waves applied, and the resulting cortical bone damage. With the Siemens Lithostar Plus with overhead module, electromagnetic shock waves, generated under water with energy densities of 0.23, 0.33, 0.42, or 0.54 mJ/mm2, corresponding with power settings 2, 4, 6, and 8, were applied to bone specimens, i.e., of rabbit femurs and tibiae. Prior to exposure to the shock waves, the bones were mounted on a specially constructed perspex holder which could be placed in a water-filled test basin with an elastic membrane in the front through which the shock waves propagate without loss of energy. This setup made it possible not only to induce complete fractures, but also to detect the existence of a linear relationship with a Spearman rank correlation coefficient of -0.72 (P < or = 0.01) between the energy level of the shock waves and the severity of the cortical bone defects. The latter findings are especially of great importance because this means that the process can be controlled and that the cortical effects will be predictable and reproducible. This study should be considered a preliminary test concerning the effects of high energy shock wave on bone.(ABSTRACT TRUNCATED AT 250 WORDS)

  5. Time Related Changes of Mineral and Collagen and Their Roles in Cortical Bone Mechanics of Ovariectomized Rabbits.

    Directory of Open Access Journals (Sweden)

    Xin-Xin Wen

    Full Text Available As cortical bone has a hierarchical structure, the macroscopic bone strength may be affected by the alterations of mineral crystal and collagen, which are main components of cortical bone. Limited studies focused on the time related alterations of these two components in osteoporosis, and their contributions to bone mechanics at tissue level and whole-bone level. Therefore, the purpose of this study was to elucidate the time related changes of mineral and collagen in cortical bone of ovariectomized (OVX rabbits, and to relate these changes to cortical bone nanomechanics and macromechanics. 40 Rabbits (7-month-old were randomly allocated into two groups (OVX and sham. OVX group received bilateral ovariectomy operation. Sham group received sham-OVX operation. Cortical bone quality of five rabbits in each group were assessed by DXA, μCT, nanoindentation, Fourier transform infrared (FTIR spectroscopy and biomechanical tests (3-point bending of femoral midshaft at pre-OVX, 4, 6, and 8 weeks after OVX. As time increased from pre-OVX to 8 weeks, the mineral to matrix ratio decreased with time, while both collagen crosslink ratio and crystallinity increased with time in OVX group. Elastic modulus and hardness measured by nanoindentation, whole-bone strength measured by biomechanical tests all decreased in OVX group with time. Bone material properties measured by FTIR correlated well with nano or whole-bone level mechanics. However, bone mineral density (BMD, structure, tissue-level and whole-bone mechanical properties did not change with age in sham group. Our study demonstrated that OVX could affect the tissue-level mechanics and bone strength of cortical bone. And this influence was attributed to the time related alterations of mineral and collagen properties, which may help us to design earlier interventions and more effective treatment strategies on osteoporosis.

  6. Safe Harvesting of Outer Table Parietal Bone Grafts Using an Oscillating Saw and a Bone Scraper : A Refinement of Technique for Harvesting Cortical and "Cancellous"-Like Calvarial Bone

    NARCIS (Netherlands)

    Schortinghuis, Jurjen; Putters, Thomas F.; Raghoebar, Gerry M.

    2012-01-01

    Calvarial bone is a readily available source of bone for preimplantation augmentation procedures of the alveolar process. However, the calvaria consist mostly of cortical bone, and cancellous bone of the diploic space is scarce. A bone scraper (Safescraper Twist; META, Reggio Emilia, Italy) was used

  7. Histological analysis of the alterations on cortical bone channels network after radiotherapy: A rabbit study.

    Science.gov (United States)

    Rabelo, Gustavo Davi; Beletti, Marcelo Emílio; Dechichi, Paula

    2010-10-01

    The aim of this study was to evaluate the effects of radiotherapy in cortical bone channels network. Fourteen rabbits were divided in two groups and test group received single dose of 15 Gy cobalt-60 radiation in tibia, bilaterally. The animals were sacrificed and a segment of tibia was removed and histologically processed. Histological images were taken and had their bone channels segmented and called regions of interest (ROI). Images were analyzed through developed algorithms using the SCILAB mathematical environment, getting percentage of bone matrix, ROI areas, ROI perimeters, their standard deviations and Lacunarity. The osteocytes and empty lacunae were also counted. Data were evaluated using Kolmogorov-Smirnov, Mann Whitney, and Student's t test (P lacunarity were found between groups. In conclusion, the radiotherapy causes reduction of bone matrix and modifies the morphology of bone channels network. © 2010 Wiley-Liss, Inc.

  8. Bone turnover markers are associated with higher cortical porosity, thinner cortices, and larger size of the proximal femur and non-vertebral fractures.

    Science.gov (United States)

    Shigdel, Rajesh; Osima, Marit; Ahmed, Luai A; Joakimsen, Ragnar M; Eriksen, Erik F; Zebaze, Roger; Bjørnerem, Åshild

    2015-12-01

    Bone turnover markers (BTM) predict bone loss and fragility fracture. Although cortical porosity and cortical thinning are important determinants of bone strength, the relationship between BTM and cortical porosity has, however, remained elusive. We therefore wanted to examine the relationship of BTM with cortical porosity and risk of non-vertebral fracture. In 211 postmenopausal women aged 54-94 years with non-vertebral fractures and 232 age-matched fracture-free controls from the Tromsø Study, Norway, we quantified femoral neck areal bone mineral density (FN aBMD), femoral subtrochanteric bone architecture, and assessed serum levels of procollagen type I N-terminal propeptide (PINP) and C-terminal cross-linking telopeptide of type I collagen (CTX). Fracture cases exhibited higher PINP and CTX levels, lower FN aBMD, larger total and medullary cross-sectional area (CSA), thinner cortices, and higher cortical porosity of the femoral subtrochanter than controls (p≤0.01). Each SD increment in PINP and CTX was associated with 0.21-0.26 SD lower total volumetric BMD, 0.10-0.14 SD larger total CSA, 0.14-0.18 SD larger medullary CSA, 0.13-0.18 SD thinner cortices, and 0.27-0.33 SD higher porosity of the total cortex, compact cortex, and transitional zone (all p≤0.01). Moreover, each SD of higher PINP and CTX was associated with increased odds for fracture after adjustment for age, height, and weight (ORs 1.49; 95% CI, 1.20-1.85 and OR 1.22; 95% CI, 1.00-1.49, both pfracture after accounting for FN aBMD, cortical porosity or cortical thickness (OR ranging from 1.31 to 1.39, p ranging from 0.005 to 0.028). In summary, increased BTM levels are associated with higher cortical porosity, thinner cortices, larger bone size and higher odds for fracture. We infer that this is produced by increased periosteal apposition, intracortical and endocortical remodeling; and that these changes in bone architecture are predisposing to fracture.

  9. 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.

  10. Age-related changes in collagen properties and mineralization in cancellous and cortical bone in the porcine mandibular condyle.

    Science.gov (United States)

    Willems, Nop M B K; Langenbach, Geerling E J; Everts, Vincent; Mulder, Lars; Grünheid, Thorsten; Bank, Ruud A; Zentner, Andrej; van Eijden, Theo M G J

    2010-04-01

    Collagen is an important constituent of bone, and it has been suggested that changes in collagen and mineral properties of bone are interrelated during growth. The aim of this study was to quantify age-related changes in collagen properties and the degree of mineralization of bone (DMB). The DMB in cancellous and cortical bone samples from the mandibular condyle of 35 female pigs aged 0-100 weeks was determined using micro-computed tomography. Subsequently, the amount of collagen and the number of pentosidine (Pen), hydroxylysylpyridinoline (HP), and lysylpyridinoline (LP) cross-links were quantified by means of high-performance liquid chromatography. The amount of collagen increased with age in cancellous bone but remained unchanged in cortical bone. The number of Pen and LP cross-links decreased in both bone types. In contrast, the number of HP cross-links decreased only in cancellous bone. The sum of the number of HP and LP cross-links decreased with age in cancellous bone only. The DMB increased in cancellous and cortical bone. It was concluded that the largest changes in the number of mature collagen cross-links and the mineralization in porcine cancellous and cortical bone take place before the age of 40 weeks. The low number of mature cross-links after this age suggests that the bone turnover rate continues to be high and thereby prevents the development of mature cross-links.

  11. The effects of glucocorticoid on microarchitecture, collagen, mineral and mechanical properties of sheep femur cortical bone

    DEFF Research Database (Denmark)

    Ding, Ming; Danielsen, Carl Christian; Overgaard, Søren

    2011-01-01

    of 3 months without treatment. Group 3 was left untreated and served as controls. All sheep received a restricted diet with low calcium and phosphorus. At sacrifice, cortical bone samples from the femur midshaft of each sheep were harvested, micro-CT scanned and subjected to three-point bending...... the groups, while there was a trend towards decreasing bending mechanical properties in the glucocorticoid-2 group. In conclusion, 7 months of glucocorticoid treatment with malnutrition had a significant impact on the cortical microarchitecture of the sheep femur midshaft. These observed changes occurred 3...

  12. In situ observation of fracture behavior of canine cortical bone under bending

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Zilan X. [Department of Orthopaedics, Medical University of South Carolina, 96 Jonathan Lucas Street Suite 708 MSC 622, Charleston, SC 29425 (United States); Department of Mechanical Engineering, University of South Carolina, 300 Main Street, Columbia, SC 29208 (United States); Xu, Zhi-Hui [Department of Mechanical Engineering, University of South Carolina, 300 Main Street, Columbia, SC 29208 (United States); An, Yuehuei H. [Department of Orthopaedics, Medical University of South Carolina, 96 Jonathan Lucas Street Suite 708 MSC 622, Charleston, SC 29425 (United States); Department of Orthopaedic Surgery, Southside Hospital, North Shore-LIJ Health System, 217 East Main Street, Bay Shore, NY 11706 (United States); Li, Xiaodong, E-mail: xl3p@virginia.edu [Department of Mechanical Engineering, University of South Carolina, 300 Main Street, Columbia, SC 29208 (United States); Department of Mechanical and Aerospace Engineering, University of Virginia, 122 Engineer' s Way, Charlottesville, VA 22904 (United States)

    2016-05-01

    Cortical bone provides many important body functions and maintains the rigidness and elasticity of bone. A common failure mode for bone structure is fracture under a bending force. In the current study, the fracture behavior of canine cortical bone under three-point bending was observed in situ using an atomic force microscope (AFM), a scanning electron microscope (SEM), and an optical microscope to examine the fracture process in detail. Nanoindentation was carried out to determine the elastic modulus and hardness of different building blocks of the canine cortical bone. The results have shown that the special structure of Haversian systems has significant effects on directing crack propagation. Although Haversian systems contain previously believed weak points, and micro-cracks initiate within Haversian systems, our findings have demonstrated that macro-cracks typically form around the boundaries of Haversian systems, i.e. the cement lines. Micro-cracks that developed inside Haversian systems have the functions of absorbing and dissipating energy and slow down on expanding when interstitial tissue cannot hold any more pressure, then plastic deformation and fracture occur. - Highlights: • Macro- and micro-cracks occur in unique patterns in the bone fracturing process under a bending force. • Early developed micro-cracks inside Haversian systems absorb and dissipate energy in order to delay fracture initiation. • The mechanical properties of Haverisan systems and its surrounding structures influence the developments of macro- and micro-crack formation. • Previously believed weak spots in the bone matrix are not necessarily the origins of fracture development.

  13. Chronic Hyperglycemia Modulates Rat Osteoporotic Cortical Bone Microarchitecture into Less Fragile Structures

    Directory of Open Access Journals (Sweden)

    Cristina de Mello-Sampayo

    2017-01-01

    Full Text Available There is controversy concerning the diabetes impact on bone quality, notorious in type 2 diabetic postmenopausal women. One pointed cause might be uncontrolled glycemia. In this study, the effect of chronic hyperglycemia in bone turnover, morphology, and biomechanics was evaluated in female Wistar rats in the presence/absence of estrogens (ovariectomy. Animals (n=28 were divided into sham, ovariectomized (OVX, hyperglycemic (streptozotocin 40 mg/kg, single-dose i.p.-STZ, and hyperglycemic-ovariectomized (STZ + OVX animals. Blood biomarkers were estimated 60 days postovariectomy. Body weight, vertebral microarchitecture (L4-histomorphometry, femur biomechanical properties (bending tests, tibia ultrastructure (scanning electron microscopy, and femur and urinary calcium (atomic absorption were also evaluated. The increased PINP/CTX ratio of hyperglycemic animals and the similar ratio between STZ + OVX and healthy animals contrasting with the lower ratio of OVX (in line with its histomorphometric data suggest a tendency for improved bone formation in hyperglycemic-ovariectomized animals. The increased tibia medullar canal, which contrasts with the unaffected cortical thickness of both hyperglycemic groups while that of OVX decreased, was associated to the increased stiffness and strength of STZ + OVX bones compared to those of OVX, in line with the observed ultrastructure. Concluding, chronic hyperglycemia in ovariectomized female rats causes bone morphological changes that translate positively in the ultrastructure and mechanical properties of cortical bones.

  14. Cortical bone growth and maturational changes in dwarf rats induced by recombinant human growth hormone

    Science.gov (United States)

    Martinez, D. A.; Orth, M. W.; Carr, K. E.; Vanderby, R. Jr; Vailas, A. C.

    1996-01-01

    The growth hormone (GH)-deficient dwarf rat was used to investigate recombinant human (rh) GH-induced bone formation and to determine whether rhGH facilitates simultaneous increases in bone formation and bone maturation during rapid growth. Twenty dwarf rats, 37 days of age, were randomly assigned to dwarf plus rhGH (GH; n = 10) and dwarf plus vehicle (n = 10) groups. The GH group received 1.25 mg rhGH/kg body wt two times daily for 14 days. Biochemical, morphological, and X-ray diffraction measurements were performed on the femur middiaphysis. rhGH stimulated new bone growth in the GH group, as demonstrated by significant increases (P bone length (6%), middiaphyseal cross-sectional area (20%), and the amount of newly accreted bone collagen (28%) in the total pool of middiaphyseal bone collagen. Cortical bone density, mean hydroxyapatite crystal size, and the calcium and collagen contents (microgram/mm3) were significantly smaller in the GH group (P bone collagen maturation, and mean hydroxyapatite crystal size may be independently regulated during rapid growth.

  15. Cortical bone tissue resists fatigue fracture by deceleration and arrest of microcrack growth.

    Science.gov (United States)

    Akkus, O; Rimnac, C M

    2001-06-01

    Knowledge of kinetics of fatigue crack growth of microcracks is important so as to understand the dynamics of bone adaptation, remodeling, and the etiology of fatigue-based failures of cortical bone tissue. In this respect, theoretical models (Taylor, J. Biomech., 31 (1998) 587-592; Taylor and Prendergast, Proc. Instn. Mech. Engrs. Part H 211 (1997) 369-375) of microcrack growth in cortical bone have predicted a decreasing microcrack growth rate with increasing microcrack length. However, these predictions have not been observed directly. This study investigated microcrack growth and arrest through observations of surface microcracks during cyclic loading (R=0.1, 50-80MPa) of human femoral cortical bone (male, n=4, age range: 37-40yr) utilizing a video microscopy system. The change in crack length and orientation of eight surface microcracks were measured with the number of fatigue cycles from four specimens. At the applied cyclic stresses, the microcracks propagated and arrested in generally less than 10,000 cycles. The fatigue crack growth rate of all microcracks decreased with increasing crack length following initial identification, consistent with theoretical predictions. The growth rate of the microcracks was observed to be in the range of 5x10(-5) to 5x10(-7)mmcycle(-1). In addition, many of the microcracks were observed not to grow beyond 150 microm and a cyclic stress intensity factor of 0.5MNm(-3/2). The results of this study suggest that cortical bone tissue may resist fracture at the microscale by deceleration of fatigue crack growth and arrest of microcracks.

  16. High-calcium diet modulates effects of long-term prolactin exposure on the cortical bone calcium content in ovariectomized rats.

    Science.gov (United States)

    Charoenphandhu, Narattaphol; Tudpor, Kukiat; Thongchote, Kanogwun; Saengamnart, Wasana; Puntheeranurak, Supaporn; Krishnamra, Nateetip

    2007-02-01

    -calcium diet. The present results thus indicated that the adult cortical bones were potentially direct targets of prolactin. Moreover, the effects of high physiological prolactin on cortical bones were age dependent and were observed only under the modulation of high-calcium diet condition.

  17. Decoupling Action Potential Bias from Cortical Local Field Potentials

    Directory of Open Access Journals (Sweden)

    Stephen V. David

    2010-01-01

    Full Text Available Neurophysiologists have recently become interested in studying neuronal population activity through local field potential (LFP recordings during experiments that also record the activity of single neurons. This experimental approach differs from early LFP studies because it uses high impendence electrodes that can also isolate single neuron activity. A possible complication for such studies is that the synaptic potentials and action potentials of the small subset of isolated neurons may contribute disproportionately to the LFP signal, biasing activity in the larger nearby neuronal population to appear synchronous and cotuned with these neurons. To address this problem, we used linear filtering techniques to remove features correlated with spike events from LFP recordings. This filtering procedure can be applied for well-isolated single units or multiunit activity. We illustrate the effects of this correction in simulation and on spike data recorded from primary auditory cortex. We find that local spiking activity can explain a significant portion of LFP power at most recording sites and demonstrate that removing the spike-correlated component can affect measurements of auditory tuning of the LFP.

  18. 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

  19. Cortical evoked potentials recorded from the guinea pig without averaging.

    Science.gov (United States)

    Walloch, R A

    1975-01-01

    Potentials evoked by tonal pulses and recorded with a monopolar electrode on the pial surface over the auditory cortex of the guinea pig are presented. These potentials are compared with average potentials recorded in previous studies with an electrode on the dura. The potentials recorded by these two techniques have similar waveforms, peak latencies and thresholds. They appear to be generated within the same region of the cerebral cortex. As can be expected, the amplitude of the evoked potentials recorded from the pial surface is larger than that recorded from the dura. Consequently, averaging is not needed to extract the evoked potential once the dura is removed. The thresholds for the evoked cortical potential are similar to behavioral thresholds for the guinea pig at high frequencies; however, evoked potential thresholds are eleveate over behavioral thresholds at low frequencies. The removal of the dura and the direct recording of the evoked potential appears most appropriate for acute experiments. The recording of an evoked potential with dura electrodes empploying averaging procedures appears most appropriate for chronic studies.

  20. Experimental investigations of forces and torque in conventional and ultrasonically-assisted drilling of cortical bone.

    Science.gov (United States)

    Alam, K; Mitrofanov, A V; Silberschmidt, V V

    2011-03-01

    Bone drilling is widely used in orthopaedics and surgery; it is a technically demanding surgical procedure. Recent technological improvements in this area are focused on efforts to reduce forces in bone drilling. This study focuses on forces and a torque required for conventional and ultrasonically-assisted tool penetration into fresh bovine cortical bone. Drilling tests were performed with two drilling techniques, and the influence of drilling speed, feed rate and parameters of ultrasonic vibration on the forces and torque was studied. Ultrasonically-assisted drilling (UAD) was found to reduce a drilling thrust force and torque compared to conventional drilling (CD). The mechanism behind lower levels of forces and torque was explored, using high-speed filming of a drill-bone interaction zone, and was linked to the chip shape and character of its formation. It is expected that UAD will produce holes with minimal effort and avoid unnecessary damage and accompanying pain during the incision.

  1. CD44 deficiency inhibits unloading-induced cortical bone loss through downregulation of osteoclast activity.

    Science.gov (United States)

    Li, Yuheng; Zhong, Guohui; Sun, Weijia; Zhao, Chengyang; Zhang, Pengfei; Song, Jinping; Zhao, Dingsheng; Jin, Xiaoyan; Li, Qi; Ling, Shukuan; Li, Yingxian

    2015-01-01

    The CD44 is cellular surface adhesion molecule that is involved in physiological processes such as hematopoiesis, lymphocyte homing and limb development. It plays an important role in a variety of cellular functions including adhesion, migration, invasion and survival. In bone tissue, CD44 is widely expressed in osteoblasts, osteoclasts and osteocytes. However, the mechanisms underlying its role in bone metabolism remain unclear. We found that CD44 expression was upregulated during osteoclastogenesis. CD44 deficiency in vitro significantly inhibited osteoclast activity and function by regulating the NF-κB/NFATc1-mediated pathway. In vivo, CD44 mRNA levels were significantly upregulated in osteoclasts isolated from the hindlimb of tail-suspended mice. CD44 deficiency can reduce osteoclast activity and counteract cortical bone loss in the hindlimb of unloaded mice. These results suggest that therapeutic inhibition of CD44 may protect from unloading induced bone loss by inhibiting osteoclast activity.

  2. Guided bone regeneration (GBR) using cortical bone pins in combination with leukocyte- and platelet-rich fibrin (L-PRF).

    Science.gov (United States)

    Toffler, Michael

    2014-03-01

    Two of the fundamental requisites for guided bone regeneration (GBR) are space maintenance and primary soft-tissue closure. Allogeneic cortical bone pins measuring 2 mm in diameter in customized lengths can protect surrounding graft materials, support bioresorbable membrane barriers, and resist wound compression from the overlying soft tissues. In addition, a second-generation platelet concentrate, leukocyte- and platelet-rich fibrin (L-PRF), may be incorporated into the augmentation procedure to provide multiple growth factors, accelerate wound healing, and aid in the maintenance of primary closure over the grafted materials. Highlighting two case reports, this article features a GBR technique that uses bone pins in combination with L-PRF membranes to provide both horizontal and vertical ridge augmentation at severely compromised implant sites.

  3. 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.

  4. Experimental multiscale measurements for the mechanical identification of a cortical bone by digital image correlation.

    Science.gov (United States)

    Nguyen, Manh-Tu; Allain, Jean-Marc; Gharbi, Hakim; Desceliers, Christophe; Soize, Christian

    2016-10-01

    The implementation of the experimental methodology by optical measurements of mechanical fields, the development of a test bench, the specimen preparation, the experimental measurements, and the digital image correlation (DIC) method, have already been the object of research in the context of biological materials. Nevertheless, in the framework of the experimental identification of a mesoscopic stochastic model of the random apparent elasticity field, measurements of one specimen is required at both the macroscopic scale and the mesoscopic scale under one single loading. The nature of the cortical bone induces some difficulties, as no single speckled pattern technique is available for simultaneously obtaining the displacement at the macroscopic scale and at the mesoscopic scale. In this paper, we present a multiscale experimental methodology based on (i) an experimental protocol for one specimen of a cortical bone, (ii) its measuring bench, (iii) optical field measurements by DIC method, (iv) the experimental results, and (v) the multiscale experimental identification by solving a statistical inverse problem.

  5. Design and validation of bending test method for characterization of miniature pediatric cortical bone specimens.

    Science.gov (United States)

    Albert, Carolyne I; Jameson, John; Harris, Gerald

    2013-02-01

    Osteogenesis imperfecta is a genetic disorder of bone fragility; however, the effects of this disorder on bone material properties are not well understood. No study has yet measured bone material strength in humans with osteogenesis imperfecta. Small bone specimens are often extracted during routine fracture surgeries in children with osteogenesis imperfecta. These specimens could provide valuable insight into the effects of osteogenesis imperfecta on bone material strength; however, their small size poses a challenge to their mechanical characterization. In this study, a validated miniature three-point bending test is described that enables measurement of the flexural material properties of pediatric cortical osteotomy specimens as small as 5 mm in length. This method was validated extensively using bovine bone, and the effect of span/depth aspect ratio (5 vs 6) on the measured flexural properties was examined. The method provided reasonable results for both Young's modulus and flexural strength in bovine bone. With a span/depth ratio of 6, the median longitudinal modulus and flexural strength results were 16.1 (range: 14.4-19.3)GPa and 251 (range: 219-293)MPa, respectively. Finally, the pilot results from two osteotomy specimens from children with osteogenesis imperfecta are presented. These results provide the first measures of bone material strength in this patient population.

  6. The effect of osteoporosis treatments on fatigue properties of cortical bone tissue

    Directory of Open Access Journals (Sweden)

    Garry R. Brock

    2015-06-01

    Full Text Available Bisphosphonates are commonly prescribed for treatment of osteoporosis. Long-term use of bisphosphonates has been correlated to atypical femoral fractures (AFFs. AFFs arise from fatigue damage to bone tissue that cannot be repaired due to pharmacologic treatments. Despite fatigue being the primary damage mechanism of AFFs, the effects of osteoporosis treatments on fatigue properties of cortical bone are unknown. To examine if fatigue-life differences occur in bone tissue after different pharmacologic treatments for osteoporosis, we tested bone tissue from the femurs of sheep given a metabolic acidosis diet to induce osteoporosis, followed by treatment with a selective estrogen reception modulator (raloxifene, a bisphosphonate (alendronate or zoledronate, or parathyroid hormone (teriparatide, PTH. Beams of cortical bone tissue were created and tested in four-point bending fatigue to failure. Tissue treated with alendronate had reduced fatigue life and less modulus loss at failure compared with other treatments, while tissue treated with PTH had a prolonged fatigue life. No loss of fatigue life occurred with zoledronate treatment despite its greater binding affinity and potency compared with alendronate. Tissue mineralization measured by microCT did not explain the differences seen in fatigue behavior. Increased fatigue life with PTH suggests that current treatment methods for AFF could have beneficial effects for restoring fatigue life. These results indicate that fatigue life differs with each type of osteoporosis treatment.

  7. Effect of Aging on the Toughness of Human Cortical Bone: Evaluation by R-Curves

    Energy Technology Data Exchange (ETDEWEB)

    Kinney, J

    2004-10-08

    Age-related deterioration of the fracture properties of bone, coupled with increased life expectancy, are responsible for increasing incidence of bone fracture in the elderly, and hence, an understanding of how its fracture properties degrade with age is essential. The present study describes ex vivo fracture experiments to quantitatively assess the effect of aging on the fracture toughness properties of human cortical bone in the longitudinal direction. Because cortical bone exhibits rising crack-growth resistance with crack extension, unlike most previous studies the toughness is evaluated in terms of resistance-curve (R-curve) behavior, measured for bone taken from wide range of age groups (34-99 years). Using this approach, both the ex vivo crack-initiation and crack-growth toughness are determined and are found to deteriorate with age; the initiation toughness decreases some 40% over six decades from 40 to 100 years, while the growth toughness is effectively eliminated over the same age range. The reduction in crack-growth toughness is considered to be associated primarily with a degradation in the degree of extrinsic toughening, in particular involving crack bridging in the wake of the crack.

  8. Effect of Loading Rate and Orientation on the Compressive Response of Human Cortical Bone

    Science.gov (United States)

    2014-05-01

    Biomechanics 1975, 8, 27–40. 11. Ntim, M. M.; Bembey, A. K.; Ferguson, V. I.; Bushby, A. J. Hydration Effects on the Viscoelastic Properties of Collagen. MRS...Determination of Mechanical Properties of Human Femoral Cortical Bone by the Hopkinson Bar Stress Technique. Journal of Biomechanics 1990, 23 (11...Science and Technology 2011, 25 (9), 2211–2215. 18. Chen, W.; Song, B. Split Hopkinson (Kolsky) Bar; Springer : New York, 2010; pp 29–77. 19. Kulin, R

  9. Study of the mechanical behavior of cortical bone microstructure by the finite element method

    OpenAIRE

    Arango Villegas, Camila

    2016-01-01

    [EN] Cortical bone tissue is the responsible of giving support and structure to vertebrates. For that reason, understanding and analyzing its behavior is needed from each different hierarchical level that composes it. The lower the structural scale is, the greater the complexity and scarcity of studies in literature. These studies are relevant for understanding, preventing and solving important health problems that affect human beings. From a mechanical point of view is interesting to eval...

  10. Osteostatin-coated porous titanium can improve early bone regeneration of cortical bone defects in rats

    NARCIS (Netherlands)

    Van Der Stok, Johan; Lozano, Daniel; Chai, Yoke Chin; Amin Yavari, Saber; Bastidas Coral, Angela P.; Verhaar, Jan A N; Gómez-Barrena, Enrique; Schrooten, Jan; Jahr, Holger; Zadpoor, Amir A.; Esbrit, Pedro; Weinans, Harrie

    2015-01-01

    A promising bone graft substitute is porous titanium. Porous titanium, produced by selective laser melting (SLM), can be made as a completely open porous and load-bearing scaffold that facilitates bone regeneration through osteoconduction. In this study, the bone regenerative capacity of porous tita

  11. Investigation of hyperelastic models for nonlinear elastic behavior of demineralized and deproteinized bovine cortical femur bone.

    Science.gov (United States)

    Hosseinzadeh, M; Ghoreishi, M; Narooei, K

    2016-06-01

    In this study, the hyperelastic models of demineralized and deproteinized bovine cortical femur bone were investigated and appropriate models were developed. Using uniaxial compression test data, the strain energy versus stretch was calculated and the appropriate hyperelastic strain energy functions were fitted on data in order to calculate the material parameters. To obtain the mechanical behavior in other loading conditions, the hyperelastic strain energy equations were investigated for pure shear and equi-biaxial tension loadings. The results showed the Mooney-Rivlin and Ogden models cannot predict the mechanical response of demineralized and deproteinized bovine cortical femur bone accurately, while the general exponential-exponential and general exponential-power law models have a good agreement with the experimental results. To investigate the sensitivity of the hyperelastic models, a variation of 10% in material parameters was performed and the results indicated an acceptable stability for the general exponential-exponential and general exponential-power law models. Finally, the uniaxial tension and compression of cortical femur bone were studied using the finite element method in VUMAT user subroutine of ABAQUS software and the computed stress-stretch curves were shown a good agreement with the experimental data.

  12. Three-dimensional mapping of cortical bone thickness in subjects with different vertical facial dimensions

    Directory of Open Access Journals (Sweden)

    Mais Medhat Sadek

    2016-10-01

    Full Text Available Abstract Background The purpose of this study was to determine differences in cortical bone thickness among subjects with different vertical facial dimensions using cone beam computed tomography (CBCT. Methods From 114 pre-treatment CBCT scans, 48 scans were selected to be included in the study. CBCT-synthesized lateral cephalograms were used to categorize subjects into three groups based on their vertical skeletal pattern. Cortical bone thickness (CBT at two vertical levels (4 and 7 mm from the alveolar crest were measured in the entire tooth-bearing region in the maxilla and mandible. Results Significant group differences were detected with high-angle subjects having significantly narrower inter-radicular CBT at some sites as compared to average- and low-angle subjects. Conclusions Inter-radicular cortical bone is thinner in high-angle than in average- or low-angle subjects in few selected sites at the vertical height in which mini-implants are commonly inserted for orthodontic anchorage.

  13. Use of Cortical Bone Screws in Maxillofacial Surgery - A Prospective Study

    Science.gov (United States)

    Satish, Madatanapalli; Rahman, NM Mujeeb; Reddy, V Sridhar; Yuvaraj, A; Muliyar, Sabir; Razak, P Abdul

    2014-01-01

    Background: The aim of this study is to evaluate the various applications of cortical bone screws in oral and maxillofacial surgery. Materials & Methods: The study was conducted in a teaching hospital located in, Bangalore, India, on 20 patients. These patients were categorized into three groups depending on the applications of these screws like, for achieving intermaxillary fixation in Group-1, for treatment of simple, undisplaced fractures by “Tension wire” method in Group-2, and further application of these screws were evaluated in Group-3. Different parameters were used to evaluate the efficacy of these screws. Results: In Group-1(n=12) there was satisfactory occlusion in all the patients with minimal incidence of complications. In Group-2 (n=4) post-operative reduction and fixation was satisfactory and in Group-3 (n=4) the function of these screws was satisfactory when it was used for vestibuloplasty and also as a suspension wiring in treatment of comminuted fracture of zygoma with minimal incidence of complications. Conclusion: Use of cortical bone screws is a valid alternative for achieving intermaxillary fixation, reduction and fixation of simple, undisplaced or minimally displaced fractures through Tension wire method owing to its simplicity, economy and ease of use, and as a fixation method for apically positioned flap in vestibuloplasty procedure. How to cite the article: Satish M, Rahman NM, Reddy VS, Yuvaraj A, Muliyar S, Razak PA. Use of Cortical Bone Screws in Maxillofacial Surgery - A Prospective Study. J Int Oral Health 2014;6(2):62-7. PMID:24876704

  14. Soluble VEGFR1 reverses BMP2 inhibition of intramembranous ossification during healing of cortical bone defects.

    Science.gov (United States)

    Hu, Kai; Besschetnova, Tatiana Y; Olsen, Bjorn R

    2016-09-07

    BMP2 is widely used for promotion of bone repair and regeneration. However, bone formation induced by BMP2 is quite variable. Bone forming progenitor cells in different locations appear to respond to BMP2 in different ways, and repair outcomes can vary as a consequence of modulating effects by other factors. In this study, we have examined the effects of VEGF on BMP2-induced repair of a cortical bone defect, a 1 mm diameter drill hole, in the proximal tibia of mice. Treatment of the defect with either a bolus of PBS or soluble VEGFR1 (sVEGFR1), a decoy receptor for VEGF, had the same effects on bone formation via intramembranous ossification in the defect and cartilage formation and injured periosteum, during the healing process. In contrast, treatment with BMP2 inhibited intramembranous bone formation in the defect while it promoted cartilage and endochondral bone formation in the injured periosteum compared with mice treated with PBS or sVEGFR1. The inhibitory effect of BMP2 on bone formation was unlikely due to increased osteoclast activity and decreased invasion of blood vessels in the defect. Most importantly, co-delivery of BMP2 and sVEGFR1 reversed the inhibition of intramembranous bone formation by BMP2. Furthermore, the decreased accumulation of collagen and production of bone matrix proteins in the defect of groups with BMP2 treatment could also be prevented by co-delivery of BMP2 and sVEGFR1. Our data indicate that introducing a VEGF-binding protein, such as sVEGFR1, to reduce levels of extracellular VEGF, may enhance the effects of BMP2 on intramembranous bone formation. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

  15. Vestibular receptors contribute to cortical auditory evoked potentials.

    Science.gov (United States)

    Todd, Neil P M; Paillard, Aurore C; Kluk, Karolina; Whittle, Elizabeth; Colebatch, James G

    2014-03-01

    Acoustic sensitivity of the vestibular apparatus is well-established, but the contribution of vestibular receptors to the late auditory evoked potentials of cortical origin is unknown. Evoked potentials from 500 Hz tone pips were recorded using 70 channel EEG at several intensities below and above the vestibular acoustic threshold, as determined by vestibular evoked myogenic potentials (VEMPs). In healthy subjects both auditory mid- and long-latency auditory evoked potentials (AEPs), consisting of Na, Pa, N1 and P2 waves, were observed in the sub-threshold conditions. However, in passing through the vestibular threshold, systematic changes were observed in the morphology of the potentials and in the intensity dependence of their amplitude and latency. These changes were absent in a patient without functioning vestibular receptors. In particular, for the healthy subjects there was a fronto-central negativity, which appeared at about 42 ms, referred to as an N42, prior to the AEP N1. Source analysis of both the N42 and N1 indicated involvement of cingulate cortex, as well as bilateral superior temporal cortex. Our findings are best explained by vestibular receptors contributing to what were hitherto considered as purely auditory evoked potentials and in addition tentatively identify a new component that appears to be primarily of vestibular origin.

  16. Ratio between mature and immature enzymatic cross-links correlates with post-yield cortical bone behavior: An insight into greenstick fractures of the child fibula.

    Science.gov (United States)

    Berteau, Jean-Philippe; Gineyts, Evelyne; Pithioux, Martine; Baron, Cécile; Boivin, Georges; Lasaygues, Philippe; Chabrand, Patrick; Follet, Hélène

    2015-10-01

    As a determinant of skeletal fragility, the organic matrix is responsible for the post-yield and creep behavior of bone and for its toughness, while the mineral apatite acts on stiffness. Specific to the fibula and ulna in children, greenstick fractures show a plastic in vivo mechanical behavior before bone fracture. During growth, the immature form of collagen enzymatic cross-links gradually decreases, to be replaced by the mature form until adolescence, subsequently remaining constant throughout adult life. However, the link between the cortical bone organic matrix and greenstick fractures in children remains to be explored. Here, we sought to determine: 1) whether plastic bending fractures can occur in vitro, by testing cortical bone samples from children's fibula and 2) whether the post-yield behavior (ωp plastic energy) of cortical bone before fracture is related to total quantity of the collagen matrix, or to the quantity of mature and immature enzymatic cross-links and the quantity of non-enzymatic cross-links. We used a two-step approach; first, a 3-point microbending device tested 22 fibula machined bone samples from 7 children and 3 elderly adults until fracture. Second, biochemical analysis by HPLC was performed on the sample fragments. When pooling two groups of donors, children and elderly adults, results show a rank correlation between total energy dissipated before fracture and age and a linear correlation between plastic energy dissipated before fracture and ratio of immature/mature cross-links. A collagen matrix with more immature cross-links (i.e. a higher immature/mature cross-link ratio) is more likely to plastically deform before fracture. We conclude that this ratio in the sub-nanostructure of the organic matrix in cortical bone from the fibula may go some way towards explaining the variance in post-yield behavior. From a clinical point of view, therefore, our results provide a potential explanation of the presence of greenstick fractures in

  17. A mathematical model of cortical bone remodeling at cellular level under mechanical stimulus

    Institute of Scientific and Technical Information of China (English)

    Qing-Hua Qin; Ya-Nan Wang

    2012-01-01

    A bone cell population dynamics model for cortical bone remodeling under mechanical stimulus is developed in this paper.The external experiments extracted from the literature which have not been used in the creation of the model are used to test the validity of the model.Not only can the model compare reasonably well with these experimental results such as the increase percentage of final values of bone mineral content (BMC) and bone fracture energy (BFE) among different loading schemes (which proves the validity of the model),but also predict the realtime development pattern of BMC and BFE,as well as the dynamics of osteoblasts (OBA),osteoclasts (OCA),nitric oxide (NO) and prostaglandin E2 (PGE2) for each loading scheme,which can hardly be monitored through experiment.In conclusion,the model is the first of its kind that is able to provide an insight into the quantitative mechanism of bone remodeling at cellular level by which bone cells are activated by mechanical stimulus in order to start resorption/formation of bone mass.More importantly,this model has laid a solid foundation based on which future work such as systemic control theory analysis of bone remodeling under mechanical stimulus can be investigated.The to-be identified control mechanism will help to develop effective drugs and combined nonpharmacological therapies to combat bone loss pathologies.Also this deeper understanding of how mechanical forces quantitatively interact with skeletal tissue is essential for the generation of bone tissue for tissue replacement purposes in tissue engineering.

  18. Neutron activation analysis of medullar and cortical bone tissues from animals; Analise por ativacao com neutrons de tecidos osseos medular e cortical de animais

    Energy Technology Data Exchange (ETDEWEB)

    Takata, Marcelo Kazuo; Saiki, Mitiko [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil). Supervisao de Radioquimica

    2000-07-01

    In this work, neutron activation analysis was applied in the determination of the elements Ba, Br, Ca, Cl, Cr, Fe, K, Mg, Mn, Na, P, Rb, Sb, Sc, Sr and Zn present in animal bone tissues. The obtained results indicated a significant difference between the elemental concentrations present in medullar and cortical tissues. The results obtained for bone tissues from distinct animal species were also different. (author)

  19. Decreased bone turnover with balanced resorption and formation prevent cortical bone loss during disuse (hibernation) in grizzly bears (Ursus arctos horribilis).

    Science.gov (United States)

    McGee, Meghan E; Maki, Aaron J; Johnson, Steven E; Nelson, O Lynne; Robbins, Charles T; Donahue, Seth W

    2008-02-01

    Disuse uncouples bone formation from resorption, leading to increased porosity, decreased bone geometrical properties, and decreased bone mineral content which compromises bone mechanical properties and increases fracture risk. However, black bear bone properties are not adversely affected by aging despite annual periods of disuse (i.e., hibernation), which suggests that bears either prevent bone loss during disuse or lose bone and subsequently recover it at a faster rate than other animals. Here we show decreased cortical bone turnover during hibernation with balanced formation and resorption in grizzly bear femurs. Hibernating grizzly bear femurs were less porous and more mineralized, and did not demonstrate any changes in cortical bone geometry or whole bone mechanical properties compared to active grizzly bear femurs. The activation frequency of intracortical remodeling was 75% lower during hibernation than during periods of physical activity, but the normalized mineral apposition rate was unchanged. These data indicate that bone turnover decreases during hibernation, but osteons continue to refill at normal rates. There were no changes in regional variation of porosity, geometry, or remodeling indices in femurs from hibernating bears, indicating that hibernation did not preferentially affect one region of the cortex. Thus, grizzly bears prevent bone loss during disuse by decreasing bone turnover and maintaining balanced formation and resorption, which preserves bone structure and strength. These results support the idea that bears possess a biological mechanism to prevent disuse osteoporosis.

  20. Dark-field transmission electron microscopy of cortical bone reveals details of extrafibrillar crystals.

    Science.gov (United States)

    Schwarcz, Henry P; McNally, Elizabeth A; Botton, Gianluigi A

    2014-12-01

    In a previous study we showed that most of the mineral in bone is present in the form of "mineral structures", 5-6nm-thick, elongated plates which surround and are oriented parallel to collagen fibrils. Using dark-field transmission electron microscopy, we viewed mineral structures in ion-milled sections of cortical human bone cut parallel to the collagen fibrils. Within the mineral structures we observe single crystals of apatite averaging 5.8±2.7nm in width and 28±19nm in length, their long axes oriented parallel to the fibril axis. Some appear to be composite, co-aligned crystals as thin as 2nm. From their similarity to TEM images of crystals liberated from deproteinated bone we infer that we are viewing sections through platy crystals of apatite that are assembled together to form the mineral structures.

  1. Cluster analysis of infrared spectra of rabbit cortical bone samples during maturation and growth.

    Science.gov (United States)

    Kobrina, Yevgeniya; Turunen, Mikael J; Saarakkala, Simo; Jurvelin, Jukka S; Hauta-Kasari, Markku; Isaksson, Hanna

    2010-12-01

    Bone consists of an organic and an inorganic matrix. During development, bone undergoes changes in its composition and structure. In this study we apply three different cluster analysis algorithms [K-means (KM), fuzzy C-means (FCM) and hierarchical clustering (HCA)], and discriminant analysis (DA) on infrared spectroscopic data from developing cortical bone with the aim of comparing their ability to correctly classify the samples into different age groups. Cortical bone samples from the mid-diaphysis of the humerus of New Zealand white rabbits from three different maturation stages (newborn (NB), immature (11 days-1 month old), mature (3-6 months old)) were used. Three clusters were obtained by KM, FCM and HCA methods on different spectral regions (amide I, phosphate and carbonate). The newborn samples were well separated (71-100% correct classifications) from the other age groups by all bone components. The mature samples (3-6 months old) were well separated (100%) from those of other age groups by the carbonate spectral region, while by the phosphate and amide I regions some samples were assigned to another group (43-71% correct classifications). The greatest variance in the results for all algorithms was observed in the amide I region. In general, FCM clustering performed better than the other methods, and the overall error was lower. The discriminate analysis results showed that by combining the clustering results from all three spectral regions, the ability to predict the correct age group for all samples increased (from 29-86% to 77-91%). This study is the first to compare several clustering methods on infrared spectra of bone. Fuzzy C-means clustering performed best, and its ability to study the degree of memberships of samples to each cluster might be beneficial in future studies of medical diagnostics.

  2. Selective laser melting-produced porous titanium scaffolds regenerate bone in critical size cortical bone defects

    NARCIS (Netherlands)

    J. van der Stok (Johan); O.P. van der Jagt (Olav); S. Amin Yavari (Saber); M.F.P. de Haas (Mirthe); J.H. Waarsing (Jan); H. Jahr (Holger); E.M.M. van Lieshout (Esther); P. Patka (Peter); J.A.N. Verhaar (Jan); A.A. Zadpoor (Amir Abbas); H.H. Weinans (Harrie)

    2013-01-01

    textabstractPorous titanium scaffolds have good mechanical properties that make them an interesting bone substitute material for large bone defects. These scaffolds can be produced with selective laser melting, which has the advantage of tailoring the structure's architecture. Reducing the strut siz

  3. The relationship between the mechanical anisotropy of human cortical bone tissue and its microstructure

    Science.gov (United States)

    Espinoza Orias, Alejandro A.

    Orthopedics research has made significant advances in the areas of biomechanics, bone implants and bone substitute materials. However, to date there is no definitive model to explain the structure-property relationships in bone as a material to enable better implant designs or to develop a true biomechanical analog of bone. The objective of this investigation was to establish a relationship between the elastic anisotropy of cortical bone tissue and its microstructure. Ultrasonic wave propagation was used to measure stiffness coefficients for specimens sectioned along the length of a human femur. The elastic constants were orthotropic and varied with anatomical location. Stiffness coefficients were generally largest at the midshaft and stiffness anisotropy ratios were largest at the distal and proximal ends. These tests were run on four additional human femurs to assess the influence of phenotypic variation, and in most cases, it was found that phenotypes do not exert a significant effect. Stiffness coefficients were shown to be correlated as a power law relation to apparent density, but anisotropy ratios were not. Texture analysis was performed on selected samples to measure the orientation distribution of the bone mineral crystals. Inverse pole figures showed that bone mineral crystals had a preferred crystallographic orientation, coincident with the long axis of the femur, which is its principal loading direction. The degree of preferred orientation was represented in Multiples of a Random Distribution (MRD), and correlated to the anisotropy ratios. Variation in elastic anisotropy was shown to be primarily due to the bone mineral orientation. The results found in this work can be used to incorporate anisotropy into structural analysis for bone as a material.

  4. In Vitro Fracture of Human Cortical Bone: Local Fracture Criteria and Toughening Mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Nalla, R; Stolken, J; Kinney, J; Ritchie, R

    2004-08-18

    A micro-mechanistic understanding of bone fracture that encompasses how cracks interact with the underlying microstructure and defines their local failure mode is lacking, despite extensive research on the response of bone to a variety of factors like aging, loading, and/or disease. Micro-mechanical models for fracture incorporating such local failure criteria have been widely developed for metallic and ceramic materials systems; however, few such deliberations have been undertaken for the fracture of bone. In fact, although the fracture event in mineralized tissues such as bone is commonly believed to be locally strain controlled, until recently there has been little experimental evidence to support this widely held belief. In the present study, a series of in vitro experiments involving a double-notch bend test geometry are performed in order to shed further light on the nature of the local cracking events that precede catastrophic fracture in bone and to define their relationship to the microstructure. Specifically, crack-microstructure interactions are examined to determine the salient toughening mechanisms in human cortical bone and to characterize how these may affect the anisotropy in fracture properties. Based on preliminary micro-mechanical models of these processes, in particular crack deflection and uncracked ligament bridging, the relative importance of these toughening mechanisms is established.

  5. Development of new criteria for cortical bone histomorphometry in femoral neck: intra- and inter-observer reproducibility.

    Science.gov (United States)

    Tong, Xiao-Yu; Malo, Markus; Tamminen, Inari S; Isaksson, Hanna; Jurvelin, Jukka S; Kröger, Heikki

    2015-01-01

    Histomorphometry is commonly applied to study bone remodeling. Histological definitions of cortical bone boundaries have not been consistent. In this study, new criteria for specific definition of the transitional zone between the cortical and cancellous bone in the femoral neck were developed. The intra- and inter-observer reproducibility of this method was determined by quantitative histomorphometry and areal overlapping analysis. The undecalcified histological sections of femoral neck specimens (n = 6; from men aged 17-59 years) were processed and scanned to acquire histological images of complete bone sections. Specific criteria were applied to define histological boundaries. "Absolute cortex area" consisted of pure cortical bone tissue only, and was defined mainly based on the size of composite canals and their distance to an additional "guide" boundary (so-called "preliminary cortex boundary," the clear demarcation line of density between compact cortex and sparse trabeculae). Endocortical bone area was defined by recognizing characteristic endocortical structures adjacent to the preliminary cortical boundary. The present results suggested moderate to high reproducibility for low-magnification parameters (e.g., cortical bone area). The coefficient of variation (CV %) ranged from 0.02 to 5.61 in the intra-observer study and from 0.09 to 16.41 in the inter-observer study. However, the intra-observer reproducibility of some high-magnification parameters (e.g., osteoid perimeter/endocortical perimeter) was lower (CV %, 0.33-87.9). The overlapping of three histological areas in repeated analyses revealed highest intra- and inter-observer reproducibility for the absolute cortex area. This study provides specific criteria for the definition of histological boundaries for femoral neck bone specimens, which may aid more precise cortical bone histomorphometry.

  6. Remodeling of heat-treated cortical bone allografts for posterior lumbar interbody fusion: serial 10-year follow-up.

    Science.gov (United States)

    Muramatsu, Koichi; Hachiya, Yudo; Izawa, Hiroyuki; Yamada, Harumoto

    2012-12-01

    We have selected heat-treated bone allografts as the graft material since the Tokai Bone Bank, the first regional bone bank in Japan, was established in 1992. In this study, we examined changes in bone mineral density (BMD), and morphology observed by magnetic resonance imaging (MRI), and histological findings of bone grafts in cases followed up for 7-10 years after bone grafting to grasp the remodeling of heat-treated cortical bone allografts for posterior lumber interbody fusion (PLIF). BMD of bone grafts was reduced by half at 10 years after grafting. MRI revealed that bone grafts were indistinguishable initially in only 22.2% of cases, whereas after a lengthy period of 10 years distinguishable in many cases. Histologically, new bone formation at the graft-host interface was observed earlier, at 1 year after grafting, than that at the periphery of canals in the specimens. The laminated structure of the cortical bone eroded over time, and fragmented bone trabeculae were observed in the specimens at 8 years or longer after grafting, though necrotic bone still remained in some sites.

  7. Glycation of human cortical and cancellous bone captures differences in the formation of Maillard reaction products between glucose and ribose.

    Science.gov (United States)

    Sroga, Grażyna E; Siddula, Alankrita; Vashishth, Deepak

    2015-01-01

    To better understand some aspects of bone matrix glycation, we used an in vitro glycation approach. Within two weeks, our glycation procedures led to the formation of advanced glycation end products (AGEs) at the levels that corresponded to approx. 25-30 years of the natural in vivo glycation. Cortical and cancellous bones from human tibias were glycated in vitro using either glucose (glucosylation) or ribose (ribosylation). Both glucosylation and ribosylation led to the formation of higher levels of AGEs and pentosidine (PEN) in cancellous than cortical bone dissected from all tested donors (young, middle-age and elderly men and women). More efficient glycation of bone matrix proteins in cancellous bone most likely depended on the higher porosity of this tissue, which facilitated better accessibility of the sugars to the matrix proteins. Notably, glycation of cortical bone from older donors led to much higher AGEs levels as compared to young donors. Such efficient in vitro glycation of older cortical bone could result from aging-related increase in porosity caused by the loss of mineral content. In addition, more pronounced glycation in vivo would be driven by elevated oxidation processes. Interestingly, the levels of PEN formation differed pronouncedly between glucosylation and ribosylation. Ribosylation generated very high levels of PEN (approx. 6- vs. 2.5-fold higher PEN level than in glucosylated samples). Kinetic studies of AGEs and PEN formation in human cortical and cancellous bone matrix confirmed higher accumulation of fluorescent crosslinks for ribosylation. Our results suggest that in vitro glycation of bone using glucose leads to the formation of lower levels of AGEs including PEN, whereas ribosylation appears to support a pathway toward PEN formation. Our studies may help to understand differences in the progression of bone pathologies related to protein glycation by different sugars, and raise awareness for excessive sugar supplementation in food and

  8. Selective laser melting-produced porous titanium scaffolds regenerate bone in critical size cortical bone defects.

    Science.gov (United States)

    Van der Stok, Johan; Van der Jagt, Olav P; Amin Yavari, Saber; De Haas, Mirthe F P; Waarsing, Jan H; Jahr, Holger; Van Lieshout, Esther M M; Patka, Peter; Verhaar, Jan A N; Zadpoor, Amir A; Weinans, Harrie

    2013-05-01

    Porous titanium scaffolds have good mechanical properties that make them an interesting bone substitute material for large bone defects. These scaffolds can be produced with selective laser melting, which has the advantage of tailoring the structure's architecture. Reducing the strut size reduces the stiffness of the structure and may have a positive effect on bone formation. Two scaffolds with struts of 120-µm (titanium-120) or 230-µm (titanium-230) were studied in a load-bearing critical femoral bone defect in rats. The defect was stabilized with an internal plate and treated with titanium-120, titanium-230, or left empty. In vivo micro-CT scans at 4, 8, and 12 weeks showed more bone in the defects treated with scaffolds. Finally, 18.4 ± 7.1 mm(3) (titanium-120, p = 0.015) and 18.7 ± 8.0 mm(3) (titanium-230, p = 0.012) of bone was formed in those defects, significantly more than in the empty defects (5.8 ± 5.1 mm(3) ). Bending tests on the excised femurs after 12 weeks showed that the fusion strength reached 62% (titanium-120) and 45% (titanium-230) of the intact contralateral femurs, but there was no significant difference between the two scaffolds. This study showed that in addition to adequate mechanical support, porous titanium scaffolds facilitate bone formation, which results in high mechanical integrity of the treated large bone defects.

  9. Effects of Loading Duration and Short Rest Insertion on Cancellous and Cortical Bone Adaptation in the Mouse Tibia.

    Science.gov (United States)

    Yang, Haisheng; Embry, Rachel E; Main, Russell P

    2017-01-01

    The skeleton's osteogenic response to mechanical loading can be affected by loading duration and rest insertion during a series of loading events. Prior animal loading studies have shown that the cortical bone response saturates quickly and short rest insertions between load cycles can enhance cortical bone formation. However, it remains unknown how loading duration and short rest insertion affect load-induced osteogenesis in the mouse tibial compressive loading model, and particularly in cancellous bone. To address this issue, we applied cyclic loading (-9 N peak load; 4 Hz) to the tibiae of three groups of 16 week-old female C57BL/6 mice for two weeks, with a different number of continuous load cycles applied daily to each group (36, 216 and 1200). A fourth group was loaded under 216 daily load cycles with a 10 s rest insertion after every fourth cycle. We found that as few as 36 load cycles per day were able to induce osteogenic responses in both cancellous and cortical bone. Furthermore, while cortical bone area and thickness continued to increase through 1200 cycles, the incremental increase in the osteogenic response decreased as load number increased, indicating a reduced benefit of the increasing number of load cycles. In the proximal metaphyseal cancellous bone, trabecular thickness increased with load up to 216 cycles. We also found that insertion of a 10 s rest between load cycles did not improve the osteogenic response of the cortical or cancellous tissues compared to continuous loading in this model given the age and sex of the mice and the loading parameters used here. These results suggest that relatively few load cycles (e.g. 36) are sufficient to induce osteogenic responses in both cortical and cancellous bone in the mouse tibial loading model. Mechanistic studies using the mouse tibial loading model to examine bone formation and skeletal mechanobiology could be accomplished with relatively few load cycles.

  10. Time-lapsed assessment of microcrack initiation and propagation in murine cortical bone at submicrometer resolution.

    Science.gov (United States)

    Voide, R; Schneider, P; Stauber, M; Wyss, P; Stampanoni, M; Sennhauser, U; van Lenthe, G H; Müller, R

    2009-08-01

    The strength of bone tissue is not only determined by its mass, but also by other properties usually referred to as bone quality, such as microarchitecture, distribution of bone cells, or microcracks and damage. It has been hypothesized that the bone ultrastructure affects microcrack initiation and propagation. Due to its high resolution, bone assessment by means of synchrotron radiation (SR)-based computed tomography (CT) allows unprecedented three-dimensional (3D) and non-invasive insights into ultrastructural bone phenotypes, such as the canal network and the osteocyte lacunar system. The aims of this study were to describe the initiation and propagation of microcracks and their relation with these ultrastructural phenotypes. To this end, femora from the two genetically distinct inbred mouse strains C3H/He (C3H) and C57BL/6 (B6) were loaded axially under compression, from 0% strain to failure, with 1% strain steps. Between each step, a high-resolution 3D image (700 nm nominal resolution) was acquired at the mid-diaphysis using SR CT for characterization and quantitative analysis of the intracortical porosity, namely the bone canal network, the osteocyte lacunar system and the emerging microcracks. For C3H mice, the canal, lacunar, and microcrack volume densities accounted typically for 1.91%, 2.11%, and 0.27% of the cortical total volume at 2% apparent strain, respectively. Due to its 3D nature, SR CT allowed to visualize and quantify also the volumetric extent of microcracks. At 2% apparent strain, the average microcrack thickness for both mouse strains was 2.0 microm for example. Microcracks initiated at canal and at bone surfaces, whereas osteocyte lacunae provided guidance to the microcracks. Moreover, we observed that microcracks could appear as linear cracks in one plane, but as diffuse cracks in a perpendicular plane. Finally, SR CT images permitted visualization of uncracked ligament bridging, which is thought to be of importance in bone toughening

  11. Antiretroviral therapy and pregnancy: effect on cortical bone status of HIV-infected women

    Directory of Open Access Journals (Sweden)

    V Giacomet

    2012-11-01

    Full Text Available Purpose of the study: Vertical transmission of HIV can be almost eliminated by an appropriate combination of preventative measures, which include the use of combination antiretroviral therapy (ARV during pregnancy, elective cesarean delivery, and avoidance of breastfeeding. Although current ARV demonstrated to be very effective to control virus infection, it has numerous side effects, including negative repercussions on bone mass. Currently there are no data regarding the bone status of HIV-infected women who received ARV during pregnancy. The aim of this study was to evaluate cortical bone status at delivery in a group of HIV-infected women who received ARV during pregnancy, to monitor the changes occurring during the first year post-partum and to compare the results with those obtained in healthy mothers. Methods: We studied 17 HIV-infected and 55 HIV-uninfected healthy women within 3 days from delivery, at 4 and 12 months postpartum (median age 36.4 years. The majority (68% of the HIV-infected mothers was on ARV containing two nucleoside reverse transcriptase inhibitors (NRTI and a protease inhibitor (PI, and 16% was on a regimen containing two NRTIs and two PIs. Other ARV regimens included the use of two NRTIs and one non-NRTI (10%, one NRTI plus one PI (3%, or two NRTIs and three PIs (3%. The median (range exposure to ARV during gestation was 14 (5-35 weeks. The great majority (91% of the women showed an undetectable viral load (<50 cp/mL at delivery. Median CD4 number at delivery was 610 (128 to 1415. Cortical bone status was evaluated by quantitative ultrasonography at the mid-tibia, and bone measurements were expressed as the speed-of-sound (SOS. Summary of results: HIV-infected women after delivery had a median SOS of 3985 (3567–4242 m/s, while the median SOS of healthy women was 4025 (3643–4250. The difference was not significant (t=0.39; P=0.69. SOS measurements at baseline, at 4, and at 12 months are shown in Table 1. SOS values

  12. Hydration and radiation effects on the residual stress state of cortical bone.

    Science.gov (United States)

    Tung, Patrick K M; Mudie, Stephen; Daniels, John E

    2013-12-01

    The change in the biaxial residual stress state of hydroxyapatite crystals and collagen fibrillar structure in sections of bovine cortical bone has been investigated as a function of dehydration and radiation dose using combined small- and wide-angle X-ray scattering. It is shown that dehydration of the bone has a pronounced effect on the residual stress state of the crystalline phase, while the impact of radiation damage alone is less dramatic. In the initial hydrated state, a biaxial compressive stress of approximately -150 MPa along the bone axis exists in the hydroxyapatite crystals. As water evaporates from the bone material, the stress state moves to a tensile state of approximately 100 MPa. The collagen fibrillar structure is initially in a tensile residual stress state when the bone is hydrated and the state increases in magnitude slightly with dehydration. Radiation dose in continually hydrated samples also reduces the initial biaxial compressive stress magnitude in the hydroxyapatite phase; however, the stress remains compressive. Radiation exposure alone does not appear to affect the stress state of the collagen fibrillar structure.

  13. Analysis of forces in conventional and ultrasonically assisted plane cutting of cortical bone.

    Science.gov (United States)

    Alam, Khurshid; Khan, Mushtaq; Silberschmidt, Vadim V

    2013-06-01

    Bone cutting is a well accepted but technically demanding surgical procedure in orthopaedics. A level of tool penetration force during cutting of bones has been the prime concern to surgeons, since it can produce unnecessary mechanical damage to surrounding tissues. Research in this area has been undertaken for many decades to find ways to minimise the cutting force. Cutting of bone with ultrasonic tools is a relatively new technique replacing conventional procedures in neuro-, dental and orthopaedic surgeries, due to its precision and safety. In this article, the level of forces produced during a chisel-like tool penetration in a fresh cortical bone is studied. The obtained force data are analysed for both conventional cutting and ultrasonically assisted cutting. Through a series of experiments, it was demonstrated that the depth of cut and parameters of ultrasonic oscillations affected the level of cutting force, the former being the main factor in both types of cutting. It was found that the tool penetration force was decreased with an increase in the ultrasonic frequency or amplitude and was not affected by the cutting speed. The rise in bone temperature was measured and was found to be insensitive to the level of cutting speed within the range used in this study.

  14. Vascular calcification is associated with cortical bone loss in chronic renal failure rats with and without ovariectomy: the calcification paradox.

    Science.gov (United States)

    De Schutter, Tineke M; Neven, Ellen; Persy, Veerle P; Behets, Geert J; Postnov, Andrei A; De Clerck, Nora M; D'Haese, Patrick C

    2011-01-01

    Increased bone loss has been associated with the development of vascular calcification in patients with chronic renal failure (CRF). In this study, the effect of impaired bone metabolism on aortic calcifications was investigated in uremic rats with or without ovariectomy. CRF was induced by administration of a 0.75% adenine/2.5% protein diet for 4 weeks. In one group, osteoporosis was induced by ovariectomy (CRF-OVX), while the other group underwent a sham-operation instead (CRF). A third group consisted of ovariectomized rats with normal renal function (OVX). At regular time intervals throughout the study, bone status and aortic calcifications were evaluated by in vivo micro-CT. At sacrifice after 6 weeks of CRF, bone histomorphometry was performed and vascular calcification was assessed by bulk calcium analysis and Von Kossa staining. Renal function was significantly impaired in the CRF-OVX and CRF groups. Trabecular bone loss was seen in all groups. In the CRF-OVX and CRF groups, trabecular bone density was restored after adenine withdrawal, which coincided with cortical bone loss and the development of medial calcifications in the aorta. No significant differences with regard to the degree of aortic calcifications were seen between the two CRF groups. Neither cortical bone loss nor calcifications were seen in the OVX group. Cortical bone loss significantly correlated with the severity of vascular calcification in the CRF-OVX and CRF groups, but no associations with trabecular bone changes were found. Cortical rather than trabecular bone loss is associated with the process of calcification in rats with adenine- induced CRF. Copyright © 2011 S. Karger AG, Basel.

  15. Novel anatomic adaptation of cortical bone to meet increased mineral demands of reproduction.

    Science.gov (United States)

    Macica, Carolyn M; King, Helen E; Wang, Meina; McEachon, Courtney L; Skinner, Catherine W; Tommasini, Steven M

    2016-04-01

    The goal of this study was to investigate the effects of reproductive adaptations to mineral homeostasis on the skeleton in a mouse model of compromised mineral homeostasis compared to adaptations in control, unaffected mice. During pregnancy, maternal adaptations to high mineral demand include more than doubling intestinal calcium absorption by increasing calcitriol production. However, calcitriol biosynthesis is impaired in HYP mice, a murine model of X-linked hypophosphatemia (XLH). In addition, there is a paucity of mineralized trabecular bone, a primary target of bone resorption during pregnancy and lactation. Because the highest density of mineral is in mature cortical bone, we hypothesized that mineral demand is met by utilizing intracortical mineral reserves. Indeed, analysis of HYP mice revealed dramatic increases in intracortical porosity characterized by elevated serum PTH and type-I collagen matrix-degrading enzyme MMP-13. We discovered an increase in carbonate ion substitution in the bone mineral matrix during pregnancy and lactation of HYP mice, suggesting an alternative mechanism of bone remodeling that maintains maternal bone mass during periods of high mineral demand. This phenomenon is not restricted to XLH, as increased carbonate in the mineral matrix also occurred in wild-type mice during lactation. Taken together, these data suggest that increased intracortical perilacunar mineral turnover also contributes to maintaining phosphate levels during periods of high mineral demand. Understanding the mechanisms of skeletal contribution to mineral homeostasis is important to improving the treatment and prevention of fracture risk and bone fragility for female patients with XLH, but also provides important insight into the role and unique adaptations of the maternal skeleton to the demands of fetal development and the needs of postnatal nutrition. Copyright © 2016 Elsevier Inc. All rights reserved.

  16. Inflammatory response and bone healing capacity of two porous calcium phosphate ceramics in critical size cortical bone defects.

    Science.gov (United States)

    Chatterjea, Anindita; van der Stok, Johan; Danoux, Charlène B; Yuan, Huipin; Habibovic, Pamela; van Blitterswijk, Clemens A; Weinans, Harrie; de Boer, Jan

    2014-05-01

    In the present study, two open porous calcium phosphate ceramics, β-tricalcium phosphate (β-TCP), and hydroxyapatite (HA) were compared in a critical-sized femoral defect in rats. Previous comparisons of these two ceramics showed significantly greater osteoinductive potential of β-TCP upon intramuscular implantation and a better performance in a spinal fusion model in dogs. Results of the current study also showed significantly more bone formation in defects grafted with β-TCP compared to HA; however, both the ceramics were not capable of increasing bone formation to such extend that it bridges the defect. Furthermore, a more pronounced degradation of β-TCP was observed as compared to HA. Progression of inflammation and initiation of new bone formation were assessed for both materials at multiple time points by histological and fluorochrome-based analyses. Until 12 days postimplantation, a strong inflammatory response in absence of new bone formation was observed in both ceramics, without obvious differences between the two materials. Four weeks postimplantation, signs of new bone formation were found in both β-TCP and HA. At 6 weeks, inflammation had subsided in both ceramics while bone deposition continued. In conclusion, the two ceramics differed in the amount of bone formed after 8 weeks of implantation, whereas no differences were found in the duration of the inflammatory phase after implantation or initiation of new bone formation.

  17. 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.

  18. Grating-evoked cortical potentials and perceived contrast (A)

    Science.gov (United States)

    Strasburger, Hans; Scheidler, Wolfgang; Rentschler, Ingo

    Unlike subjective perception of contrast, steady-state evoked cortical potentials (VEP's) elicited with counterphased gratings may vary abruptly with changes in spatial frequency.(1) To avoid possible artifacts we developed a digital fast-sweep technique for investigating this discrepancy. In most of our 13 subjects, at high stimulus contrasts the dependency of VEP amplitude on spatial frequency had two pronounced peaks separated by a sharp notch at around 3 cycles per degree. With decreasing contrast these variations leveled out, and a unimodal response function was obtained at low contrast. A linear relationship between log contrast and VEP amplitude(2) was found for any given spatial frequency only in the low-contrast range. With increasing contrast the VEP amplitude saturated at a rate that depended clearly on spatial frequency, with a nonmonotonous dependency occurring at intermediate spatial frequencies. The latter phenomenon of oversaturation apparently gave rise to the above-mentioned bimodal response characteristic. Results of a careful analysis of VEP phase lags are added. (1) C. W. Tyler et al., Brain Res. 33, 535 (1978). (2) F. W. Campbell and L. Maffei, J. Physiol. 207, 635 (1970).

  19. NPY neuron-specific Y2 receptors regulate adipose tissue and trabecular bone but not cortical bone homeostasis in mice.

    Directory of Open Access Journals (Sweden)

    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

  20. In vitro ultrasonic and mechanic characterization of the modulus of elasticity of children cortical bone.

    Science.gov (United States)

    Berteau, Jean-Philippe; Baron, Cécile; Pithioux, Martine; Launay, Franck; Chabrand, Patrick; Lasaygues, Philippe

    2014-07-01

    The assessment of elastic properties in children's cortical bone is a major challenge for biomechanical engineering community, more widely for health care professionals. Even with classical clinical modalities such as X-ray tomography, MRI, and/or echography, inappropriate diagnosis can result from the lack of reference values for children bone. This study provides values for elastic properties of cortical bone in children using ultrasonic and mechanical measurements, and compares them with adult values. 18 fibula samples from 8 children (5-16 years old, mean age 10.6 years old ±4.4) were compared to 16 fibula samples from 3 elderly adults (more than 65 years old). First, the dynamic modulus of elasticity (Edyn) and Poisson's ratio (ν) are evaluated via an ultrasonic method. Second, the static modulus of elasticity (Esta) is estimated from a 3-point microbending test. The mean values of longitudinal and transverse wave velocities measured at 10 MHz for the children's samples are respectively 3.2mm/μs (±0.5) and 1.8mm/μs (±0.1); for the elderly adults' samples, velocities are respectively 3.5mm/μs (±0.2) and 1.9 mm/μs (±0.09). The mean Edyn and the mean Esta for the children's samples are respectively 15.5 GPa (±3.4) and 9.1 GPa (±3.5); for the elderly adults' samples, they are respectively 16.7 GPa (±1.9) and 5.8 GPa (±2.1). Edyn, ν and Esta are in the same range for children's and elderly adults' bone without any parametric statistical difference; a ranking correlation between Edyn and Esta is shown for the first time.

  1. Organ and tissue level properties are more sensitive to age than osteocyte lacunar characteristics in rat cortical bone

    DEFF Research Database (Denmark)

    Wittig, Nina; Bach-Gansmo, Fiona Linnea; Birkbak, Mie Elholm

    2016-01-01

    lacunar properties in rat cortical bone. Femora of 14 to 42-week-old female Wistar rats were investigated using multiple complementary techniques including X-ray micro-computed tomography and biomechanical testing. The body weight, femoral length, aBMD, load to fracture, tissue volume, bone volume......, and tissue density were found to increase rapidly with age at 14–30 weeks. At the age of 30–42 weeks, the growth rate appeared to decrease. However, no accompanying changes were found in osteocyte lacunar properties such as lacunar volume, ellipsoidal radii, lacunar stretch, lacunar oblateness, or lacunar...... orientation with animal age. Hence, the evolution of organ and tissue level properties with age in rat cortical bone is not accompanied by related changes in osteocyte lacunar properties. This suggests that bone microstructure and bone matrix material properties and not the geometric properties...

  2. Cortical evoked potentials to an auditory illusion: binaural beats.

    Science.gov (United States)

    Pratt, Hillel; Starr, Arnold; Michalewski, Henry J; Dimitrijevic, Andrew; Bleich, Naomi; Mittelman, Nomi

    2009-08-01

    To define brain activity corresponding to an auditory illusion of 3 and 6Hz binaural beats in 250Hz or 1000Hz base frequencies, and compare it to the sound onset response. Event-Related Potentials (ERPs) were recorded in response to unmodulated tones of 250 or 1000Hz to one ear and 3 or 6Hz higher to the other, creating an illusion of amplitude modulations (beats) of 3Hz and 6Hz, in base frequencies of 250Hz and 1000Hz. Tones were 2000ms in duration and presented with approximately 1s intervals. Latency, amplitude and source current density estimates of ERP components to tone onset and subsequent beats-evoked oscillations were determined and compared across beat frequencies with both base frequencies. All stimuli evoked tone-onset P(50), N(100) and P(200) components followed by oscillations corresponding to the beat frequency, and a subsequent tone-offset complex. Beats-evoked oscillations were higher in amplitude with the low base frequency and to the low beat frequency. Sources of the beats-evoked oscillations across all stimulus conditions located mostly to left lateral and inferior temporal lobe areas in all stimulus conditions. Onset-evoked components were not different across stimulus conditions; P(50) had significantly different sources than the beats-evoked oscillations; and N(100) and P(200) sources located to the same temporal lobe regions as beats-evoked oscillations, but were bilateral and also included frontal and parietal contributions. Neural activity with slightly different volley frequencies from left and right ear converges and interacts in the central auditory brainstem pathways to generate beats of neural activity to modulate activities in the left temporal lobe, giving rise to the illusion of binaural beats. Cortical potentials recorded to binaural beats are distinct from onset responses. Brain activity corresponding to an auditory illusion of low frequency beats can be recorded from the scalp.

  3. 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.

  4. Propagation of ultrasonic guided waves in an acrylic plate as a cortical-bone-mimicking phantom

    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)

    2014-12-15

    The present study aims to investigate the propagation of ultrasonic guided waves in an acrylic plate as a cortical-bone-mimicking phantom. The velocities of the guided waves in a 5-mm-thick acrylic plate were measured by using the axial transmission technique. A pure A0 Lamb mode could be successfully launched in the 5-mm-thick acrylic plate through a time reversal process of Lamb waves, consistent with the fact that the time reversal process can automatically compensate for the dispersive nature of Lamb waves. The experimental velocities of the slow guided wave (SGW) and the time-reversed Lamb wave were found to be in reasonable agreement with the theoretical group velocity of the A0 Lamb mode, suggesting that both the SGW and the time-reversed Lamb wave excited in the 5-mm-thick acrylic plate correspond to the A0 Lamb mode. These results suggest that the time reversal process of Lamb waves can be usefully applied to noninvasive characterization of long cortical bones.

  5. Geometric-attributes-based segmentation of cortical bone slides using optimized neural networks.

    Science.gov (United States)

    Hage, Ilige S; Hamade, Ramsey F

    2016-05-01

    In cortical bone, solid (lamellar and interstitial) matrix occupies space left over by porous microfeatures such as Haversian canals, lacunae, and canaliculi-containing clusters. In this work, pulse-coupled neural networks (PCNN) were used to automatically distinguish the microfeatures present in histology slides of cortical bone. The networks' parameters were optimized using particle swarm optimization (PSO). When forming the fitness functions for the PSO, we considered the microfeatures' geometric attributes-namely, their size (based on measures of elliptical perimeter or area), shape (based on measures of compactness or the ratio of minor axis length to major axis length), and a two-way combination of these two geometric attributes. This hybrid PCNN-PSO method was further enhanced for pulse evaluation by combination with yet another method, adaptive threshold (AT), where the PCNN algorithm is repeated until the best threshold is found corresponding to the maximum variance between two segmented regions. Together, this framework of using PCNN-PSO-AT constitutes, we believe, a novel framework in biomedical imaging. Using this framework and extracting microfeatures from only one training image, we successfully extracted microfeatures from other test images. The high fidelity of all resultant segments was established using quantitative metrics such as precision, specificity, and Dice indices.

  6. Comparison of mechanical and ultrasound elastic modulus of ovine tibial cortical bone.

    Science.gov (United States)

    Grant, Caroline A; Wilson, Lance J; Langton, Christian; Epari, Devakar

    2014-07-01

    Finite element models of bones can be created by deriving geometry from an X-ray CT scan. Material properties such as the elastic modulus can then be applied using either a single or set of homogeneous values, or individual elements can have local values mapped onto them. Values for the elastic modulus can be derived from the CT density values using an elasticity versus density relationship. Many elasticity-density relationships have been reported in the literature for human bone. However, while ovine in vivo models are common in orthopaedic research, no work has been done to date on creating FE models of ovine bones. To create these models and apply relevant material properties, an ovine elasticity-density relationship needs to be determined. Using fresh frozen ovine tibias the apparent density of regions of interest was determined from a clinical CT scan. The bones were the sectioned into cuboid samples of cortical bone from the regions of interest. Ultrasound was used to determine the elastic modulus in each of three directions - longitudinally, radially and tangentially. Samples then underwent traditional compression testing in each direction. The relationships between apparent density and both ultrasound, and compression modulus in each direction were determined. Ultrasound testing was found to be a highly repeatable non-destructive method of calculating the elastic modulus, particularly suited to samples of this size. The elasticity-density relationships determined in the longitudinal direction were very similar between the compression and ultrasound data over the density range examined. A clear difference was seen in the elastic modulus between the longitudinal and transverse directions of the bone samples, and a transverse elasticity-density relationship is also reported.

  7. Cortical lamina technique: A therapeutic approach for lateral ridge augmentation using guided bone regeneration

    Science.gov (United States)

    Thomas, Raison; Baron, Tarun-Kumar; Shah, Rucha; Mehta, Dhoom-Singh

    2017-01-01

    Background The present study aimed at evaluating the efficacy of a novel technique, the bone lamina technique, in horizontal ridge augmentation clinically & radiographically using a combination of allogenic cortical shell, particulate xenograft and resorbable collagen membrane. Material and Methods Localized horizontal ridge defects, in ten patients (6 male, 4 female), with bucco-palatal ridge width less than 5 mm were included in this study. Localised ridge augmentation was performed using bone lamina technique with mineralised allogenic shell of 1 mm thickness trimmed to the appropriate size using stereo-lithographic models and fixed to the recipient site with stainless steel micro-screws of 1 mm diameter. The space between the shell & host bone was filled with particulate xenograft followed by placement of collagen membrane and primary closure of the site. Clinical parameters including ridge width before & after flap reflection & radiographic (CBCT) ridge width measurements were recorded pre-operatively,and six months after the augmentation procedure. Results obtained were analysed statistically. Results The mean clinical ridge width before flap reflection (BFR), after flap reflection (AFR) & radiographically was 3.7 ± 0.74 mm, 2 ± 0.70 mm & 1.77 ± 0.71 mm respectively at baseline which increased to 6.8 ± 0.95 mm, 5.15 ± 0.98 mm & 4.90 ± 0.90 mm with a mean gain in ridge width of 3.1 ± 0.63 mm (p< 0.005), 3.15 ± 0.63 mm (p<0.005) & 3.13 ± 0.70 mm (p< 0.005) respectively. Conclusions The present study demonstrates that bone lamina technique can be effective means of horizontal ridge augmentation and the use of mineralized allograft in combination with xenograft and collagen membrane leads to good amount of bone regeneration for subsequent implant placement. Key words:Dental implant, guided bone regeneration, horizontal ridge defect, ridge augmentation. PMID:28149458

  8. Individual-specific multi-scale finite element simulation of cortical bone of human proximal femur

    Energy Technology Data Exchange (ETDEWEB)

    Ascenzi, Maria-Grazia, E-mail: mgascenzi@mednet.ucla.edu [UCLA/Orthopaedic Hospital, Department of Orthopaedic Surgery, Rehabilitation Bldg, Room 22-69, 1000 Veteran Avenue, University of California, Los Angeles, CA 90095 (United States); Kawas, Neal P., E-mail: nealkawas@ucla.edu [UCLA/Orthopaedic Hospital, Department of Orthopaedic Surgery, Rehabilitation Bldg, Room 22-69, 1000 Veteran Avenue, University of California, Los Angeles, CA 90095 (United States); Lutz, Andre, E-mail: andre.lutz@hotmail.de [Institute of Biomechanics and Numerical Mechanics, Leibniz University Hannover, 30167 Hannover (Germany); Kardas, Dieter, E-mail: kardas@ibnm.uni-hannover.de [ContiTech Vibration Control, Jaedekamp 30 None, 30419 Hannover (Germany); Nackenhorst, Udo, E-mail: nackenhorst@ibnm.uni-hannover.de [Institute of Biomechanics and Numerical Mechanics, Leibniz University Hannover, 30167 Hannover (Germany); Keyak, Joyce H., E-mail: jhkeyak@uci.edu [Department of Radiological Sciences, Medical Sciences I, Bldg 811, Room B140, University of California, Irvine, CA 92697-5000 (United States)

    2013-07-01

    We present an innovative method to perform multi-scale finite element analyses of the cortical component of the femur using the individual’s (1) computed tomography scan; and (2) a bone specimen obtained in conjunction with orthopedic surgery. The method enables study of micro-structural characteristics regulating strains and stresses under physiological loading conditions. The analysis of the micro-structural scenarios that cause variation of strain and stress is the first step in understanding the elevated strains and stresses in bone tissue, which are indicative of higher likelihood of micro-crack formation in bone, implicated in consequent remodeling or macroscopic bone fracture. Evidence that micro-structure varies with clinical history and contributes in significant, but poorly understood, ways to bone function, motivates the method’s development, as does need for software tools to investigate relationships between macroscopic loading and micro-structure. Three applications – varying region of interest, bone mineral density, and orientation of collagen type I, illustrate the method. We show, in comparison between physiological loading and simple compression of a patient’s femur, that strains computed at the multi-scale model’s micro-level: (i) differ; and (ii) depend on local collagen-apatite orientation and degree of calcification. Our findings confirm the strain concentration role of osteocyte lacunae, important for mechano-transduction. We hypothesize occurrence of micro-crack formation, leading either to remodeling or macroscopic fracture, when the computed strains exceed the elastic range observed in micro-structural testing.

  9. Computational Study of the Effect of Cortical Porosity on Ultrasound Wave Propagation in Healthy and Osteoporotic Long Bones

    Directory of Open Access Journals (Sweden)

    Vassiliki T. Potsika

    2016-03-01

    Full Text Available Computational studies on the evaluation of bone status in cases of pathologies have gained significant interest in recent years. This work presents a parametric and systematic numerical study on ultrasound propagation in cortical bone models to investigate the effect of changes in cortical porosity and the occurrence of large basic multicellular units, simply called non-refilled resorption lacunae (RL, on the velocity of the first arriving signal (FAS. Two-dimensional geometries of cortical bone are established for various microstructural models mimicking normal and pathological tissue states. Emphasis is given on the detection of RL formation which may provoke the thinning of the cortical cortex and the increase of porosity at a later stage of the disease. The central excitation frequencies 0.5 and 1 MHz are examined. The proposed configuration consists of one point source and multiple successive receivers in order to calculate the FAS velocity in small propagation paths (local velocity and derive a variation profile along the cortical surface. It was shown that: (a the local FAS velocity can capture porosity changes including the occurrence of RL with different number, size and depth of formation; and (b the excitation frequency 0.5 MHz is more sensitive for the assessment of cortical microstructure.

  10. Evaluation of cortical bone thickness of mandible with cone beam computed tomography for orthodontic mini implant installation

    Directory of Open Access Journals (Sweden)

    Seyed Hossein Moslemzade

    2014-07-01

    Full Text Available Background: Achieving maximum anchorage without movement of the teeth in anchorage unit has been a great challenge in orthodontics and the success of the treatment plan highly depends on it. In this case, using orthodontic mini-implants can make a huge difference. The objective of this retrospective study was to measure thickness of cortical bone at prospective mini-implant placement sites in mandible in order to understand stability aspects of mini-implant placement by using cone-beam computed tomography (CBCT images. Materials and Methods: Initial 3-dimensional images of 40 adult patients were studied. The cortical bone thickness was obtained at the alveolar processes from canine to second molar at 5 different vertical levels from the cementoenamel junction (CEJ. To determine the cortical bone thickness, tangent lines were drawn buccolingually to the roots in axial section and a third line was drawn from the middle of these two lines, and the cortical bone thickness was measured where the third line crossed the buccal cortex.   Results: Mandibular and buccal cortical bone thicknesses were 0.79 to 2.49 mm, respectively. There was a statistically significant increase from the CEJ to the apex (P<0.001, while this increase was not statically significant at interdental area of teeth #3 and #4. Comparing the 4 mm section in all sites showed significant increase from anterior to posterior. Conclusion: Based on our results, the cortical bone thickness mostly follows a pattern and depends on the interradicular site rather than individual differences.     Key words: Cone-beam computed tomography; orthodontic anchorage procedures

  11. [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.

  12. Low and High-Frequency Field Potentials of Cortical Networks ...

    Science.gov (United States)

    Neural networks grown on microelectrode arrays (MEAs) have become an important, high content in vitro assay for assessing neuronal function. MEA experiments typically examine high- frequency (HF) (>200 Hz) spikes, and bursts which can be used to discriminate between different pharmacological agents/chemicals. However, normal brain activity is additionally composed of integrated low-frequency (0.5-100 Hz) field potentials (LFPs) which are filtered out of MEA recordings. The objective of this study was to characterize the relationship between HF and LFP neural network signals, and to assess the relative sensitivity of LFPs to selected neurotoxicants. Rat primary cortical cultures were grown on glass, single-well MEA chips. Spontaneous activity was sampled at 25 kHz and recorded (5 min) (Multi-Channel Systems) from mature networks (14 days in vitro). HF (spike, mean firing rate, MFR) and LF (power spectrum, amplitude) components were extracted from each network and served as its baseline (BL). Next, each chip was treated with either 1) a positive control, bicuculline (BIC, 25μM) or domoic acid (DA, 0.3μM), 2) or a negative control, acetaminophen (ACE, 100μM) or glyphosate (GLY, 100μM), 3) a solvent control (H2O or DMSO:EtOH), or 4) a neurotoxicant, (carbaryl, CAR 5, 30μM ; lindane, LIN 1, 10μM; permethrin, PERM 25, 50μM; triadimefon, TRI 5, 65μM). Post treatment, 5 mins of spontaneous activity was recorded and analyzed. As expected posit

  13. Synchrotron ultraviolet microspectroscopy on rat cortical bone: involvement of tyrosine and tryptophan in the osteocyte and its environment.

    Directory of Open Access Journals (Sweden)

    Stéphane Pallu

    Full Text Available Alcohol induced osteoporosis is characterized by a bone mass decrease and microarchitecture alterations. Having observed an excess in osteocyte apoptosis, we aimed to assess the bone tissue biochemistry, particularly in the osteocyte and its environment. For this purpose, we used a model of alcohol induced osteoporosis in rats. Bone sections of cortical bone were investigated using synchrotron UV-microspectrofluorescence at subcellular resolution. We show that bone present three fluorescence peaks at 305, 333 and 385 nm, respectively corresponding to tyrosine, tryptophan and collagen. We have determined that tyrosine/collagen and tryptophan/collagen ratios were higher in the strong alcohol consumption group. Tryptophan is related to the serotonin metabolism involved in bone formation, while tyrosine is involved in the activity of tyrosine kinases and phosphatases in osteocytes. Our experiment represents the first combined synchrotron UV microspectroscopy analysis of bone tissue with a quantitative biochemical characterization in the osteocyte and surrounding matrix performed separately.

  14. A weighted osteon morphotype score outperforms regional osteon percent prevalence calculations for interpreting cortical bone adaptation.

    Science.gov (United States)

    Skedros, John G; Kiser, Casey J; Mendenhall, Shaun D

    2011-01-01

    Using circularly polarized light microscopy,we described a weighted-scoring method for quantifying regional distributions of six secondary osteon morphotypes(Skedros et al.: Bone 44 (2009) 392-403). This osteon morphotype score (MTS) strongly correlated with "tension" and "compression" cortices produced by habitual bending. In the present study, we hypothesized that the osteon MTS is superior to a relatively simpler method based on the percent prevalence (PP) of these osteon morphotypes. This was tested in proximal femoral diaphyses of adult chimpanzees and habitually bent bones: calcanei from sheep, deer, and horses, radii from sheep and horses, and third metacarpals (MC3s) from horses. Sheep tibiae were examined because their comparatively greater torsion/shear would not require regional variations in osteon morphotypes. Predominant collagen fiber orientation (CFO), a predictor of regionally prevalent/predominant strain mode, was quantified as image gray levels (birefringence). Ten PP calculations were conducted. Although PP calculations were similar to the osteon MTS in corroborating CFO differences between "tension" and "compression" cortices of the chimpanzee femora and most of the habitually bent bones, PP calculations failed to show a compression/tension difference in equine MC3s and sheep radii. With the exception of the prevalence of the "distributed" osteon morphotype, correlations of PP calculations with CFO were weak and/or negative. By contrast, the osteon MTS consistently showed positive correlations with predominant CFO. Compared with the osteon MTS and predominant CFO, regional variations in PP of osteon morpho types are not stronger predictors of nonuniform strain distributions produced by bending.

  15. Reduced cortical bone compositional heterogeneity with bisphosphonate treatment in postmenopausal women with intertrochanteric and subtrochanteric fractures.

    Science.gov (United States)

    Donnelly, Eve; Meredith, Dennis S; Nguyen, Joseph T; Gladnick, Brian P; Rebolledo, Brian J; Shaffer, Andre D; Lorich, Dean G; Lane, Joseph M; Boskey, Adele L

    2012-03-01

    Reduction of bone turnover with bisphosphonate treatment alters bone mineral and matrix properties. Our objective was to investigate the effect of bisphosphonate treatment on bone tissue properties near fragility fracture sites in the proximal femur in postmenopausal women with osteoporosis. The mineral and collagen properties of corticocancellous biopsies from the proximal femur were compared in bisphosphonate-naive (-BIS, n = 20) and bisphosphonate-treated (+BIS, n = 20, duration 7 ± 5 years) patients with intertrochanteric (IT) and subtrochanteric (ST) fractures using Fourier transform infrared imaging (FTIRI). The mean values of the FTIRI parameter distributions were similar across groups, but the widths of the parameter distributions tended to be reduced in the +BIS group relative to the -BIS group. Specifically, the widths of the cortical collagen maturity and crystallinity were reduced in the +BIS group relative to those of the -BIS group by 28% (+BIS 0.45 ± 0.18 versus -BIS 0.63 ± 0.28, p = 0.03) and 17% (+BIS 0.087 ± 0.012 versus -BIS 0.104 ± 0.036, p = 0.05), respectively. When the tissue properties were examined as a function of fracture morphology within the +BIS group, the FTIR parameters were generally similar regardless of fracture morphology. However, the cortical mineral:matrix ratio was 8% greater in tissue from patients with atypical ST fractures (n = 6) than that of patients with typical (IT or spiral ST) fractures (n = 14) (Atypical 5.6 ± 0.3 versus Typical 5.2 ± 0.5, p = 0.03). Thus, although the mean values of the FTIR properties were similar in both groups, the tissue in bisphosphonate-treated patients had a more uniform composition than that of bisphosphonate-naive patients. The observed reductions in mineral and matrix heterogeneity may diminish tissue-level toughening mechanisms.

  16. Non destructive characterization of cortical bone micro-damage by nonlinear resonant ultrasound spectroscopy.

    Directory of Open Access Journals (Sweden)

    Sylvain Haupert

    Full Text Available The objective of the study was to evaluate the ability of a nonlinear ultrasound technique, the so-called nonlinear resonant ultrasound spectroscopy (NRUS technique, for detecting early microdamage accumulation in cortical bone induced by four-point bending fatigue. Small parallelepiped beam-shaped human cortical bone specimens were subjected to cyclic four-point bending fatigue in several steps. The specimens were prepared to control damage localization during four-point bending fatigue cycling and to unambiguously identify resonant modes for NRUS measurements. NRUS measurements were achieved to follow the evolution of the nonlinear hysteretic elastic behavior during fatigue-induced damage. After each fatigue step, a small number of specimens was removed from the protocol and set apart to quantitatively assess the microcrack number density and length using synchrotron radiation micro-computed tomography (SR-µCT. The results showed a significant effect of damage steps on the nonlinear hysteretic elastic behavior. No significant change in the overall length of microcracks was observed in damaged regions compared to the load-free control regions. Only an increased number of shortest microcracks, those in the lowest quartile, was noticed. This was suggestive of newly formed microcracks during the early phases of damage accumulation. The variation of nonlinear hysteretic elastic behavior was significantly correlated to the variation of the density of short microcracks. Our results suggest that the nonlinear hysteretic elastic behavior is sensitive to early bone microdamage. Therefore NRUS technique can be used to monitor fatigue microdamage progression in in vitro experiments.

  17. Elastic moduli of untreated, demineralized and deproteinized cortical bone: validation of a theoretical model of bone as an interpenetrating composite material.

    Science.gov (United States)

    Hamed, E; Novitskaya, E; Li, J; Chen, P-Y; Jasiuk, I; McKittrick, J

    2012-03-01

    A theoretical experimentally based multi-scale model of the elastic response of cortical bone is presented. It portrays the hierarchical structure of bone as a composite with interpenetrating biopolymers (collagen and non-collagenous proteins) and minerals (hydroxyapatite), together with void spaces (porosity). The model involves a bottom-up approach and employs micromechanics and classical lamination theories of composite materials. Experiments on cortical bone samples from bovine femur include completely demineralized and deproteinized bones as well as untreated bone samples. Porosity and microstructure are characterized using optical and scanning electron microscopy, and micro-computed tomography. Compression testing is used to measure longitudinal and transverse elastic moduli of all three bone types. The characterization of structure and properties of these three bone states provides a deeper understanding of the contributions of the individual components of bone to its elastic response and allows fine tuning of modeling assumptions. Very good agreement is found between theoretical modeling and compression testing results, confirming the validity of the interpretation of bone as an interpenetrating composite material.

  18. Development of a Three-Dimensional (3D Printed Biodegradable Cage to Convert Morselized Corticocancellous Bone Chips into a Structured Cortical Bone Graft

    Directory of Open Access Journals (Sweden)

    Ying-Chao Chou

    2016-04-01

    Full Text Available This study aimed to develop a new biodegradable polymeric cage to convert corticocancellous bone chips into a structured strut graft for treating segmental bone defects. A total of 24 adult New Zealand white rabbits underwent a left femoral segmental bone defect creation. Twelve rabbits in group A underwent three-dimensional (3D printed cage insertion, corticocancellous chips implantation, and Kirschner-wire (K-wire fixation, while the other 12 rabbits in group B received bone chips implantation and K-wire fixation only. All rabbits received a one-week activity assessment and the initial image study at postoperative 1 week. The final image study was repeated at postoperative 12 or 24 weeks before the rabbit scarification procedure on schedule. After the animals were sacrificed, both femurs of all the rabbits were prepared for leg length ratios and 3-point bending tests. The rabbits in group A showed an increase of activities during the first week postoperatively and decreased anterior cortical disruptions in the postoperative image assessments. Additionally, higher leg length ratios and 3-point bending strengths demonstrated improved final bony ingrowths within the bone defects for rabbits in group A. In conclusion, through this bone graft converting technique, orthopedic surgeons can treat segmental bone defects by using bone chips but with imitate characters of structured cortical bone graft.

  19. Development of a Three-Dimensional (3D) Printed Biodegradable Cage to Convert Morselized Corticocancellous Bone Chips into a Structured Cortical Bone Graft.

    Science.gov (United States)

    Chou, Ying-Chao; Lee, Demei; Chang, Tzu-Min; Hsu, Yung-Heng; Yu, Yi-Hsun; Liu, Shih-Jung; Ueng, Steve Wen-Neng

    2016-04-20

    This study aimed to develop a new biodegradable polymeric cage to convert corticocancellous bone chips into a structured strut graft for treating segmental bone defects. A total of 24 adult New Zealand white rabbits underwent a left femoral segmental bone defect creation. Twelve rabbits in group A underwent three-dimensional (3D) printed cage insertion, corticocancellous chips implantation, and Kirschner-wire (K-wire) fixation, while the other 12 rabbits in group B received bone chips implantation and K-wire fixation only. All rabbits received a one-week activity assessment and the initial image study at postoperative 1 week. The final image study was repeated at postoperative 12 or 24 weeks before the rabbit scarification procedure on schedule. After the animals were sacrificed, both femurs of all the rabbits were prepared for leg length ratios and 3-point bending tests. The rabbits in group A showed an increase of activities during the first week postoperatively and decreased anterior cortical disruptions in the postoperative image assessments. Additionally, higher leg length ratios and 3-point bending strengths demonstrated improved final bony ingrowths within the bone defects for rabbits in group A. In conclusion, through this bone graft converting technique, orthopedic surgeons can treat segmental bone defects by using bone chips but with imitate characters of structured cortical bone graft.

  20. Tensile material properties of human rib cortical bone under quasi-static and dynamic failure loading and influence of the bone microstucture on failure characteristics

    CERN Document Server

    Subit, Damien; Valazquez-Ameijide, Juan; Arregui-Dalmases, Carlos; Crandall, Jeff

    2011-01-01

    Finite element models of the thorax are under development to assist vehicle safety researchers with the design of countermeasures such as advanced restrain systems. Computational models have become more refined with increasing geometrical complexity as element size decreases. These finite element models can now capture small geometrical features with an attempt to predict fracture. However, the bone material properties currently available, and in particular the rate sensitivity, have been mainly determined from compression tests or tests on long bones. There is a need for a new set of material properties for the human rib cortical bone. With this objective, a new clamping technique was developed to test small bone coupons under tensile loading. Ten coupons were harvested from the cortical shell of the sixth and seventh left ribs from three cadavers. The coupons were tested to fracture under quasi-static (target strain rate of 0.07 %/s) and dynamic loading (target strain rate of 170 %/s). Prior to testing, eac...

  1. A 3D Multiscale Modelling of Cortical Bone Structure, Using the Inverse Identification Method: Microfibril Scale Study

    CERN Document Server

    Barkaoui, Abdelwahed

    2011-01-01

    Complexity and heterogeneity of bone tissue require a multiscale modelling to understand their mechanical behaviour and their remodelling mechanism. Human cortical bone structure consists of six structural scale levels which are the (macroscopic) cortical bone, osteonal, lamellar, fibrous, fibril and microfibril. In this paper, a 3D model based on finite elements method was achieved to study the nanomechanical behaviour of collagen Microfibril. The mechanical properties and the geometry (gap, overlap and diameter) of both tropocollagen and mineral were taken into consideration as well as the effects of cross-links. An inverse identification method has been applied to determine equivalent averaged properties in order to link up these nanoscopic characteristics to the macroscopic mechanical behaviour of bone tissue. Results of nanostructure modelling of the nanomechanical properties of strain deformation under varying cross-links were investigated in this work.

  2. 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)

  3. An Increase in Forearm Cortical Bone Size After Menopause May Influence the Estimated Bone Mineral Loss--A 28-Year Prospective Observational Study.

    Science.gov (United States)

    Karlsson, Magnus K; Ahlborg, Henrik G; Svejme, Ola; Nilsson, Jan-Åke; Rosengren, Björn E

    2016-01-01

    Areal bone mineral density (aBMD) is the most common estimate of bone mass, incorporated in the World Health Organization definition of osteoporosis. However, aBMD depends on not only the amount of mineral but also the bone size. The estimated postmenopausal decline in aBMD could because of this be influenced by changes in bone size.We measured bone mineral content (BMC; mg), aBMD (mg/cm2), and bone width (mm) by single-photon absorptiometry at the cortical site of the forearm in a population-based sample of 105 Caucasian women. We conducted 12 measurements during a 28-yr period from mean 5 yr (range: 2-9) before menopause to mean 24 yr (range: 18-28) after menopause. We calculated individual slopes for changes in the periods before menopause, 0-transient increase in forearm bone size that will influence the by aBMD estimated cortical loss in bone minerals. Published by Elsevier Inc.

  4. Microstructure and compressive mechanical properties of cortical bone in children with osteogenesis imperfecta treated with bisphosphonates compared with healthy children.

    Science.gov (United States)

    Imbert, Laurianne; Aurégan, Jean-Charles; Pernelle, Kélig; Hoc, Thierry

    2015-06-01

    Osteogenesis imperfecta (OI) is a genetic disorder characterized by a change in bone tissue quality, but little data are available to describe the factors involved at the macroscopic scale. To better understand the effect of microstructure alterations on the mechanical properties at the sample scale, we studied the structural and mechanical properties of six cortical bone samples from children with OI treated with bisphosphonates and compared them to the properties of three controls. Scanning electron microscopy, high resolution computed tomography and compression testing were used to assess these properties. More resorption cavities and a higher osteocyte lacunar density were observed in OI bone compared with controls. Moreover, a higher porosity was measured for OI bones along with lower macroscopic Young's modulus, yield stress and ultimate stress. The microstructure was impaired in OI bones; the higher porosity and osteocyte lacunar density negatively impacted the mechanical properties and made the bone more prone to fracture.

  5. Harvesting bone graft from the olecranon: a quantitative and biomechanical comparison of proximal and dorsal cortical windows.

    Science.gov (United States)

    Anderson, Matthew C; Chong, Alexander C M; Lucas, George L; Czuwala, Peter J; Wooley, Paul H

    2014-07-01

    We conducted a study to compare 2 techniques of harvesting ulna bone graft from the olecranon, one using a proximal cortical window (PCW), the other using a dorsal cortical window (DCW), in terms of cancellous bone graft quantity and ulna fracture strength after graft harvest. Cancellous bone was harvested from 8 pairs of embalmed cadaver proximal ulna. Each side of a matched pair was randomly assigned to graft harvest using either a PCW or a DCW approach. Packed bone volume (PBV) was determined by placing the harvested bone into a 3-mL syringe and compacting it with a quasi-static 25-N load. Biomechanical cantilever bending was performed on each elbow to determine load at failure (LF). Paired Student t tests were used to compare PBV and LF between the experimental and control groups. The graft PBV obtained from the matched-pair specimens was not statistically different between the PCW and DCW approaches. Ulnas subjected to proximal bone harvest exhibited higher LF than ulnas subjected to dorsal bone harvest, though the difference was not statistically significant. Compared with bone graft harvest using the traditional DCW approach, harvest using a PCW approach provides similar cancellous graft amounts and exhibits similar fracture resistance.

  6. Analysis of cortical bone porosity using synchrotron radiation microtomography to evaluate the effects of chemotherapy

    Science.gov (United States)

    Alessio, R.; Nogueira, L. P.; Salata, C.; Mantuano, A.; Almeida, A. P.; Braz, D.; de Almeida, C. E.; Tromba, G.; Barroso, R. C.

    2015-11-01

    Microporosities play important biologic and mechanical roles on health. One of the side effects caused by some chemotherapy drugs is the induction of amenorrhea, temporary or not, in premenopausal women, with a consequent decrease in estrogen production, which can lead to cortical bone changes. In the present work, the femur diaphysis of rats treated with chemotherapy drugs were evaluated by 3D morphometric parameters using synchrotron radiation microtomography. Control animals were also evaluated for comparison. The 3D tomographic images were obtained at the SYRMEP (SYnchrotron Radiation for MEdical Physics) beamline at the ELETTRA Synchrotron Laboratory in Trieste, Italy. Results showed significant differences in morphometric parameters measured from the 3D images of femur diaphysis of rats.

  7. Reference point indentation study of age-related changes in porcine femoral cortical bone.

    Science.gov (United States)

    Rasoulian, Ramin; Raeisi Najafi, Ahmad; Chittenden, Michael; Jasiuk, Iwona

    2013-06-21

    The reference point indentation (RPI) method is a microindentation technique involving successive indentation cycles. We employed RPI to measure average stiffness (Ave US), indentation distance increase (IDI), total indentation distance (TID), average energy dissipated (Ave ED), and creep indentation distance (CID) of swine femoral cortical bone (mid-diaphysis) as a function of age (1, 3.5, 6, 14.5, 24, and 48 months) and loading directions (longitudinal and transverse). The Ave US increases with animal age, while the IDI, TID, Ave ED, and CID decrease with age, for both longitudinal (transverse surface) and transverse (periosteal surface) loading directions. Longitudinal measurements generally give higher Ave US and lower IDI and TID values compared to transverse measurements. The RPI measurements show similar trends to those obtained using nanoindentation test, and ash and water content tests.

  8. 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.

  9. The effect of excitation and preparation pulses on nonslice selective 2D UTE bicomponent analysis of bound and free water in cortical bone at 3T

    Energy Technology Data Exchange (ETDEWEB)

    Li, Shihong [Department of Radiology, University of California, San Diego, California 92103-8226 (United States); Department of Radiology, Hua Dong Hospital, Fudan University, Shanghai 200040 (China); Yancheng Medical College, Jiangsu (China); The First People' s Hospital of Yancheng City, Jiangsu 224005 (China); Chang, Eric Y.; Chung, Christine B. [VA San Diego Healthcare System, San Diego, California 92161 and Department of Radiology, University of California, San Diego, California 92103-8226 (United States); Bae, Won C.; Du, Jiang, E-mail: jiangdu@ucsd.edu [Department of Radiology, University of California, San Diego, California 92103-8226 (United States); Hua, Yanqing [Department of Radiology, Hua Dong Hospital, Fudan University, Shanghai 200040 (China); Zhou, Yi [The First People' s Hospital of Yancheng City, Jiangsu 224005 (China)

    2014-02-15

    Purpose: The purpose of this study was to investigate the effect of excitation, fat saturation, long T2 saturation, and adiabatic inversion pulses on ultrashort echo time (UTE) imaging with bicomponent analysis of bound and free water in cortical bone for potential applications in osteoporosis. Methods: Six bovine cortical bones and six human tibial midshaft samples were harvested for this study. Each bone sample was imaged with eight sequences using 2D UTE imaging at 3T with half and hard excitation pulses, without and with fat saturation, long T2 saturation, and adiabatic inversion recovery (IR) preparation pulses. Single- and bicomponent signal models were utilized to calculate the T2{sup *}s and/or relative fractions of short and long T2{sup *}s. Results: For all bone samples UTE T2{sup *} signal decay showed bicomponent behavior. A higher short T2{sup *} fraction was observed on UTE images with hard pulse excitation compared with half pulse excitation (75.6% vs 68.8% in bovine bone, 79.9% vs 73.2% in human bone). Fat saturation pulses slightly reduced the short T2{sup *} fraction relative to regular UTE sequences (5.0% and 2.0% reduction, respectively, with half and hard excitation pulses for bovine bone, 6.3% and 8.2% reduction, respectively, with half and hard excitation pulses for human bone). Long T2 saturation pulses significantly reduced the long T2{sup *} fraction relative to regular UTE sequence (18.9% and 17.2% reduction, respectively, with half and hard excitation pulses for bovine bone, 26.4% and 27.7% reduction, respectively, with half and hard excitation pulses for human bone). With IR-UTE preparation the long T2{sup *} components were significantly reduced relative to regular UTE sequence (75.3% and 66.4% reduction, respectively, with half and hard excitation pulses for bovine bone, 87.7% and 90.3% reduction, respectively, with half and hard excitation pulses for human bone). Conclusions: Bound and free water T2{sup *}s and relative fractions can

  10. INTRAOPERATIVE LOCALIZATION OF CORTICAL MOTOR EVOKED POTENTIALS IN CENTRAL SULCUS LESIONS

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Objective To study direct cortical electrical stimulation technique for the recording of motor evoked potentials under general anesthesia in central sulcus lesions. Methods The largest N20-P25 response was recorded from postcentral gyrus by intraoperative monitoring of cortical motor evoked potentials in 10 patients with intracranial lesions near or in the central area. The muscles of upper extremity in all patients were activated by delivering stimulus to cortical areas continuously. Moving the cortical electrodes forward, the largest P20-N25 response, SEP phase reversal,was obtained as a motor center stimulus. In this site of cortex, a short train stimulation elicited reproducible muscle action potentials that could be observed from the oscilloscope without averaging.Results MEPs can be recorded, pre- and post-operatively, without motor deficits of upper limbs in all patients.Conclusion This technique seems to be preferable for intraoperative localization of motor evoked potentials in central sulcus lesions under total intravenous anesthesia.

  11. Multiscale approach including microfibril scale to assess elastic constants of cortical bone based on neural network computation and homogenization method

    CERN Document Server

    Barkaoui, Abdelwahed; Tarek, Merzouki; Hambli, Ridha; Ali, Mkaddem

    2014-01-01

    The complexity and heterogeneity of bone tissue require a multiscale modelling to understand its mechanical behaviour and its remodelling mechanisms. In this paper, a novel multiscale hierarchical approach including microfibril scale based on hybrid neural network computation and homogenisation equations was developed to link nanoscopic and macroscopic scales to estimate the elastic properties of human cortical bone. The multiscale model is divided into three main phases: (i) in step 0, the elastic constants of collagen-water and mineral-water composites are calculated by averaging the upper and lower Hill bounds; (ii) in step 1, the elastic properties of the collagen microfibril are computed using a trained neural network simulation. Finite element (FE) calculation is performed at nanoscopic levels to provide a database to train an in-house neural network program; (iii) in steps 2 to 10 from fibril to continuum cortical bone tissue, homogenisation equations are used to perform the computation at the higher s...

  12. Functional adaptation to mechanical loading in both cortical and cancellous bone is controlled locally and is confined to the loaded bones.

    Science.gov (United States)

    Sugiyama, Toshihiro; Price, Joanna S; Lanyon, Lance E

    2010-02-01

    In order to validate whether bones' functional adaptation to mechanical loading is a local phenomenon, we randomly assigned 21 female C57BL/6 mice at 19 weeks of age to one of three equal numbered groups. All groups were treated with isoflurane anesthesia three times a week for 2 weeks (approximately 7 min/day). During each anaesthetic period, the right tibiae/fibulae in the DYNAMIC+STATIC group were subjected to a peak dynamic load of 11.5 N (40 cycles with 10-s intervals between cycles) superimposed upon a static "pre-load" of 2.0 N. This total load of 13.5 N engendered peak longitudinal strains of approximately 1400 microstrain on the medial surface of the tibia at a middle/proximal site. The right tibiae/fibulae in the STATIC group received the static "pre-load" alone while the NOLOAD group received no artificial loading. After 2 weeks, the animals were sacrificed and both tibiae, fibulae, femora, ulnae and radii analyzed by three-dimensional high-resolution (5 mum) micro-computed tomography (microCT). In the DYNAMIC+STATIC group, the proximal trabecular percent bone volume and cortical bone volume at the proximal and middle levels of the right tibiae as well as the cortical bone volume at the middle level of the right fibulae were markedly greater than the left. In contrast, the left bones in the DYNAMIC+STATIC group showed no differences compared to the left or right bones in the NOLOAD or STATIC group. These microCT data were confirmed by two-dimensional examination of fluorochrome labels in bone sections which showed the predominantly woven nature of the new bone formed in the loaded bones. We conclude that the adaptive response in both cortical and trabecular regions of bones subjected to short periods of dynamic loading, even when this response is sufficiently vigorous to stimulate woven bone formation, is confined to the loaded bones and does not involve changes in other bones that are adjacent, contra-lateral or remote to them.

  13. 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.

  14. Liver-derived IGF-I regulates cortical bone mass but is dispensable for the osteogenic response to mechanical loading in female mice.

    Science.gov (United States)

    Svensson, Johan; Windahl, Sara H; Saxon, Leanne; Sjögren, Klara; Koskela, Antti; Tuukkanen, Juha; Ohlsson, Claes

    2016-07-01

    Low circulating IGF-I is associated with increased fracture risk. Conditional depletion of IGF-I produced in osteoblasts or osteocytes inhibits the bone anabolic effect of mechanical loading. Here, we determined the role of endocrine IGF-I for the osteogenic response to mechanical loading in young adult and old female mice with adult, liver-specific IGF-I inactivation (LI-IGF-I(-/-) mice, serum IGF-I reduced by ≈70%) and control mice. The right tibia was subjected to short periods of axial cyclic compressive loading three times/wk for 2 wk, and measurements were performed using microcomputed tomography and mechanical testing by three-point bending. In the nonloaded left tibia, the LI-IGF-I(-/-) mice had lower cortical bone area and increased cortical porosity, resulting in reduced bone mechanical strength compared with the controls. Mechanical loading induced a similar response in LI-IGF-I(-/-) and control mice in terms of cortical bone area and trabecular bone volume fraction. In fact, mechanical loading produced a more marked increase in cortical bone mechanical strength, which was associated with a less marked increase in cortical porosity, in the LI-IGF-I(-/-) mice compared with the control mice. In conclusion, liver-derived IGF-I regulates cortical bone mass, cortical porosity, and mechanical strength under normal (nonloaded) conditions. However, despite an ∼70% reduction in circulating IGF-I, the osteogenic response to mechanical loading was not attenuated in the LI-IGF-I(-/-) mice.

  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. Repair of sheep long bone cortical defects filled with COLLOSS, COLLOSS E, OSSAPLAST, and fresh iliac crest autograft.

    Science.gov (United States)

    Huffer, William E; Benedict, James J; Turner, A S; Briest, Arne; Rettenmaier, Robert; Springer, Marco; Walboomers, X F

    2007-08-01

    COLLOSS and COLLOSS E are osteoinductive bone void fillers consisting of bone collagen and noncollagenous proteins from bovine and equine bone, respectively. The aim of this study was to compare COLLOSS, COLLOSS E, iliac bone autograft, sintered beta tricalcium phosphate (beta-TCP; OSSAPLAST), and COLLOSS E plus OSSAPLAST. Materials were placed for 4, 8, or 24 weeks in 5-mm cortical bone defects in sheep long bones. Histological sections in a plane perpendicular to the long axis of the bone were used to measure the total repair area (original defect plus callus) and the area of bone within the total repair area. The incidence of defect union was also evaluated. At 4 and 8 weeks, defects treated with COLLOSS and COLLOSS E with or without OSSAPLAST had total repair and bone areas equivalent to autograft, and larger than OSSAPLAST-treated defects. At 8 weeks, the incidence of defect union was higher in defects treated with autograft or COLLOSS E plus OSSAPLAST than in untreated defects. At 24 weeks, the incidence of union was 100% in all treatment groups and 0% in untreated defects. The incidence of union was related to the degree of remodeling between 8 and 24 weeks. This was greater in all treated than nontreated defects. In conclusion, COLLOSS and COLLOSS E were equivalent to each other and to autograft, and superior to beta-TCP, in this study model.

  17. Immature muscular tissue differentiation into bone-like tissue by bone morphogenetic proteins in vitro, with ossification potential in vivo.

    Science.gov (United States)

    Hayashi, Tatsuhide; Kobayashi, Syuichiro; Asakura, Masaki; Kawase, Mayu; Ueno, Atsuko; Uematsu, Yasuaki; Kawai, Tatsushi

    2014-09-01

    The objective of this study was to induce bone formation from immature muscular tissue (IMT) in vitro, using bone morphogenetic proteins (BMPs) as a cytokine source and an expanded polytetrafluoroethylene (ePTFE) scaffold. In addition, cultured IMTs were implanted subcutaneously into Sprague-Dawley (SD) rats to determine their in vivo ossification potential. BMPs, extracted from bovine cortical bones, were applied to embryonic SD rat IMT cultures, before 2 weeks culture on ePTFE scaffolds. Osteoblast-like cells and osteoid tissues were partially identified by hematoxylin-eosin staining 2 weeks after culture. Collagen type I (Col-I), osteopontin (OP), and osteocalcin (OC) were detected in the osteoid tissues by immunohistochemical staining. OC gene expression remained low, but OP and Col-I were upregulated during the culture period. In vivo implanted IMTs showed slight radiopacity 1 week after implantation and strong radiopacity 2 and 3 weeks after implantation. One week after implantation, migration of numerous capillaries was observed and ossification was detected after 2 weeks by histological observation. These results suggest that IMTs are able to differentiate into bone-like tissue in vitro, with an ossification potential after implantation in vivo.

  18. Quantification of alterations in cortical bone geometry using Site Specificity Software in mouse models of aging and the responses to ovariectomy and altered loading

    Directory of Open Access Journals (Sweden)

    Gabriel L Galea

    2015-04-01

    Full Text Available Investigations into the effect of (remodelling stimuli on cortical bone in rodents normally rely on analysis of changes in bone mass and architecture at a narrow cross-sectional site. However, it is well established that the effects of axial loading produce site-specific changes throughout bones’ structure. Non-mechanical influences (e.g. hormones can be additional to or oppose locally-controlled adaptive responses and may have more generalized effects. Tools currently available to study site-specific cortical bone adaptation are limited. Here we applied novel Site-Specificity software to measure bone mass and architecture at each 1% site along the length of the mouse tibia from standard micro-computed tomography (μCT images. Resulting measures are directly comparable to those obtained through μCT analysis (R2 > 0.96. Site-Specificity Analysis was used to compare a number of parameters in tibiae from young adult (19-week-old versus aged (19-month-old mice; ovariectomized and entire mice; limbs subjected to short periods of axial loading or disuse induced by sciatic neurectomy. Age was associated with uniformly reduced cortical thickness and site-specific decreases in cortical area most apparent in the proximal tibia. Mechanical loading site-specifically increased cortical area and thickness in the proximal tibia. Disuse uniformly decreased cortical thickness and decreased cortical area in the proximal tibia. Ovariectomy uniformly reduced cortical area without altering cortical thickness. Differences in polar moment of inertia between experimental groups were only observed in the proximal tibia. Ageing and ovariectomy also altered eccentricity in the distal tibia. In summary, Site-Specificity Analysis provides a valuable tool for measuring changes in cortical bone mass and architecture along the entire length of a bone. Changes in the (remodelling response determined at a single site may not reflect the response at different locations within

  19. Benefits of mineralized bone cortical allograft for immediate implant placement in extraction sites: an in vivo study in dogs

    Science.gov (United States)

    2016-01-01

    Purpose The aim of the present study was to evaluate the effectiveness of using a mineralized bone cortical allograft (MBCA), with or without a resorbable collagenous membrane derived from bovine pericardium, on alveolar bone remodeling after immediate implant placement in a dog model. Methods Six mongrel dogs were included. The test and control sites were randomly selected. Four biradicular premolars were extracted from the mandible. In control sites, implants without an allograft or membrane were placed immediately in the fresh extraction sockets. In the test sites, an MBCA was placed to fill the gap between the bone socket wall and implant, with or without a resorbable collagenous membrane. Specimens were collected after 1 and 3 months. The amount of residual particles and new bone quality were evaluated by histomorphometry. Results Few residual graft particles were observed to be closely embedded in the new bone without any contact with the implant surface. The allograft combined with a resorbable collagen membrane limited the resorption of the buccal wall in height and width. The histological quality of the new bone was equivalent to that of the original bone. The MBCA improved the quality of new bone formation, with few residual particles observed at 3 months. Conclusions The preliminary results of this animal study indicate a real benefit in obtaining new bone as well as in enhancing osseointegration due to the high resorbability of cortical allograft particles, in comparison to the results of xenografts or other biomaterials (mineralized or demineralized cancellous allografts) that have been presented in the literature. Furthermore, the use of an MBCA combined with a collagen membrane in extraction and immediate implant placement limited the extent of post-extraction resorption. PMID:27800212

  20. 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

  1. Nano-structural, compositional and micro-architectural signs of cortical bone fragility at the superolateral femoral neck in elderly hip fracture patients vs. healthy aged controls.

    Science.gov (United States)

    Milovanovic, Petar; Rakocevic, Zlatko; Djonic, Danijela; Zivkovic, Vladimir; Hahn, Michael; Nikolic, Slobodan; Amling, Michael; Busse, Bjoern; Djuric, Marija

    2014-07-01

    To unravel the origins of decreased bone strength in the superolateral femoral neck, we assessed bone structural features across multiple length scales at this cortical fracture initiating region in postmenopausal women with hip fracture and in aged-matched controls. Our combined methodological approach encompassed atomic force microscopy (AFM) characterization of cortical bone nano-structure, assessment of mineral content/distribution via quantitative backscattered electron imaging (qBEI), measurement of bone material properties by reference point indentation, as well as evaluation of cortical micro-architecture and osteocyte lacunar density. Our findings revealed a wide range of differences between the fracture group and the controls, suggesting a number of detrimental changes at various levels of cortical bone hierarchical organization that may render bone fragile. Namely, mineral crystals at external cortical bone surfaces of the fracture group were larger (65.22nm±41.21nm vs. 36.75nm±18.49nm, pfracture group. Fracture cases showed nearly 35% higher cortical porosity and showed significantly reduced osteocyte lacunar density compared to controls (226±27 vs. 247±32#/mm(2), p=0.05). Along with increased crystal size, a shift towards higher mineralization and a tendency to increased cortical porosity and reduced osteocyte lacunar number delineate that cortical bone of the superolateral femoral neck bears distinct signs of fragility at various levels of its structural organization. These results contribute to the understanding of hierarchical bone structure changes in age-related fragility. Copyright © 2014 Elsevier Inc. All rights reserved.

  2. Cortical bone resorption rate in elderly persons: Estimates from long-term in vivo measurements of 90Sr in the skeleton

    Energy Technology Data Exchange (ETDEWEB)

    Shagina, N. B.; Tolstykh, E. I.; Degteva, M. O.; Anspaugh, L. R.; Napier, Bruce A.

    2012-06-01

    The rate of cortical bone resorption was assessed from long-term in vivo measurements of 90Sr content in the skeleton for men aged 50-80 years and for women 0-30 years after menopause. Measurements of 90Sr were conducted with a whole body counter for residents of the Techa Riverside communities (Southern Urals, Russia), who ingested large amounts of 90Sr as a result of releases of liquid radioactive wastes into the river from the Mayak plutonium facility in early 1950s. The results of this study showed an increase in the rate of cortical bone resorption in both men and women, as based on the use of accidentally ingested 90Sr as a tracer for bone metabolism. In men there was a continuous gradual increase in the rate of cortical bone resorption after 55 years from 2.8 to 4.5%/year by the age of 75 years. In women, there was a doubled increase in the rate of cortical bone resorption after menopause of up to 6%/year; then the rate remained unchanged for 10-12 years with a subsequent gradual decline down to 5-5.5%/year. Comparison of the rate of cortical bone resorption in men and women older than 55 years showed that women expressed significantly higher levels of cortical bone resorption.

  3. Cortical stimulation and tooth pulp evoked potentials in rats: a model of direct anti-nociception.

    Science.gov (United States)

    Rusina, Robert; Barek, Stephane; Vaculin, Simon; Azérad, Jean; Rokyta, Richard

    2010-01-01

    While the effect of cortex stimulation on pain control is widely accepted, its physiological basis remains poorly understood. We chose an animal model of pain to study the influence of sensorimotor cortex stimulation on tooth pulp stimulation evoked potentials (TPEPs). Fifteen awake rats implanted with tooth pulp, cerebral cortex, and digastric muscle electrodes were divided into three groups, receiving 60 Hz, 40 Hz and no cortical stimulation, respectively. TPEPs were recorded before, one, three and five hours after continuous stimulation. We observed an inverse relationship between TPEP amplitude and latency with increasing tooth pulp stimulation. The amplitudes of the early components of TPEPs increased and their latency decreased with increasing tooth pulp stimulation intensity. Cortical stimulation decreased the amplitude of TPEPs; however, neither the latencies of TPEPs nor the jaw-opening reflex were changed after cortical stimulation. The decrease in amplitude of TPEPs after cortical stimulation may reflect its anti-nociceptive effect.

  4. Membrane potential dynamics of populations of cortical neurons during auditory streaming.

    Science.gov (United States)

    Farley, Brandon J; Noreña, Arnaud J

    2015-10-01

    How a mixture of acoustic sources is perceptually organized into discrete auditory objects remains unclear. One current hypothesis postulates that perceptual segregation of different sources is related to the spatiotemporal separation of cortical responses induced by each acoustic source or stream. In the present study, the dynamics of subthreshold membrane potential activity were measured across the entire tonotopic axis of the rodent primary auditory cortex during the auditory streaming paradigm using voltage-sensitive dye imaging. Consistent with the proposed hypothesis, we observed enhanced spatiotemporal segregation of cortical responses to alternating tone sequences as their frequency separation or presentation rate was increased, both manipulations known to promote stream segregation. However, across most streaming paradigm conditions tested, a substantial cortical region maintaining a response to both tones coexisted with more peripheral cortical regions responding more selectively to one of them. We propose that these coexisting subthreshold representation types could provide neural substrates to support the flexible switching between the integrated and segregated streaming percepts.

  5. Experimental investigations and finite element simulation of cutting heat in vibrational and conventional drilling of cortical bone.

    Science.gov (United States)

    Wang, Yu; Cao, Meng; Zhao, Xiangrui; Zhu, Gang; McClean, Colin; Zhao, Yuanyuan; Fan, Yubo

    2014-11-01

    Heat generated during bone drilling could cause irreversible thermal damage, which can lead to bone necrosis or even osteomyelitis. In this study, vibrational drilling was applied to fresh bovine bones to investigate the cutting heat in comparison with conventional drilling through experimental investigation and finite element analysis (FEA). The influence of vibrational frequency and amplitude on cutting heat generation and conduction were studied. The experimental results showed that, compared with the conventional drilling, vibrational drilling could significantly reduce the cutting temperature in drilling of cortical bone (P<0.05): the cutting temperature tended to decrease with increasing vibrational frequency and amplitude. The FEA results also showed that the vibrational amplitude holds a significant effect on the cutting heat conduction.

  6. Towards an optimal paradigm for simultaneously recording cortical and brainstem auditory evoked potentials.

    Science.gov (United States)

    Bidelman, Gavin M

    2015-02-15

    Simultaneous recording of brainstem and cortical event-related brain potentials (ERPs) may offer a valuable tool for understanding the early neural transcription of behaviorally relevant sounds and the hierarchy of signal processing operating at multiple levels of the auditory system. To date, dual recordings have been challenged by technological and physiological limitations including different optimal parameters necessary to elicit each class of ERP (e.g., differential adaptation/habitation effects and number of trials to obtain adequate response signal-to-noise ratio). We investigated a new stimulus paradigm for concurrent recording of the auditory brainstem frequency-following response (FFR) and cortical ERPs. The paradigm is "optimal" in that it uses a clustered stimulus presentation and variable interstimulus interval (ISI) to (i) achieve the most ideal acquisition parameters for eliciting subcortical and cortical responses, (ii) obtain an adequate number of trials to detect each class of response, and (iii) minimize neural adaptation/habituation effects. Comparison between clustered and traditional (fixed, slow ISI) stimulus paradigms revealed minimal change in amplitude or latencies of either the brainstem FFR or cortical ERP. The clustered paradigm offered over a 3× increase in recording efficiency compared to conventional (fixed ISI presentation) and thus, a more rapid protocol for obtaining dual brainstem-cortical recordings in individual listeners. We infer that faster recording of subcortical and cortical potentials might allow more complete and sensitive testing of neurophysiological function and aid in the differential assessment of auditory function. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. Combined treatment with GH and IGF-I: additive effect on cortical bone mass but not on linear bone growth in female rats.

    Science.gov (United States)

    Sundström, Katja; Cedervall, Therese; Ohlsson, Claes; Camacho-Hübner, Cecilia; Sävendahl, Lars

    2014-12-01

    The growth-promoting effect of combined therapy with GH and IGF-I in normal rats is not known. We therefore investigated the efficacy of treatment with recombinant human (rh)GH and/or rhIGF-I on longitudinal bone growth and bone mass in intact, prepubertal, female Sprague-Dawley rats. rhGH was injected twice daily sc (5 mg/kg·d) and rhIGF-I continuously infused sc (2.2 or 4.4 mg/kg·d) for 28 days. Longitudinal bone growth was monitored by weekly x-rays of tibiae and nose-anus length measurements, and tibial growth plate histomorphology was analyzed. Bone mass was evaluated by peripheral quantitative computed tomography. In addition, serum levels of IGF-I, rat GH, acid labile subunit, IGF binding protein-3, 150-kDa ternary complex formation, and markers of bone formation and degradation were measured. Monotherapy with rhGH was more effective than rhIGF-I (4.4 mg/kg·d) to increase tibia and nose-anus length, whereas combined therapy did not further increase tibia, or nose-anus, lengths or growth plate height. In contrast, combined rhGH and rhIGF-I (4.4 mg/kg·d) therapy had an additive stimulatory effect on cortical bone mass vs rhGH alone. Combined treatment with rhGH and rhIGF-I resulted in markedly higher serum IGF-I concentrations vs rhGH alone but did not compromise the endogenous secretion of GH. We conclude that rhIGF-I treatment augments cortical bone mass but does not further improve bone growth in rhGH-treated young, intact, female rats.

  8. The significance of crack-resistance curves to the mixed-mode fracture toughness of human cortical bone

    Energy Technology Data Exchange (ETDEWEB)

    Zimmermann, Elizabeth A.; Launey, Maximilien E.; Ritchie, Robert O.

    2010-03-25

    The majority of fracture mechanics studies on the toughness of bone have been performed under tensile loading. However, it has recently been shown that the toughness of human cortical bone in the transverse (breaking) orientation is actually much lower in shear (mode II) than in tension (mode I); a fact that is physiologically relevant as in vivo bone is invariably loaded multiaxially. Since bone is a material that derives its fracture resistance primarily during crack growth through extrinsic toughening mechanisms, such as crack deflection and bridging, evaluation of its toughness is best achieved through measurements of the crack-resistance or R-curve, which describes the fracture toughness as a function of crack extension. Accordingly, in this study, we attempt to measure for the first time the R-curve fracture toughness of human cortical bone under physiologically relevant mixed-mode loading conditions. We show that the resulting mixed-mode (mode I + II) toughness depends strongly on the crack trajectory and is the result of the competition between the paths of maximum mechanical driving force and 'weakest' microstructural resistance.

  9. Metastatic potential of an aneurysmal bone cyst.

    NARCIS (Netherlands)

    Luijtgaarden, A.C.M. van de; Veth, R.P.H.; Slootweg, P.J.; Wijers-Koster, P.M.; Schultze Kool, L.J.; Bovee, J.V.; Graaf, W.T.A. van der

    2009-01-01

    Aneurysmal bone cysts (ABCs) are benign bone tumors consisting of blood-filled cavities lined by connective tissue septa. Recently, the hypothesis that ABCs are lesions reactive to local hemodynamics has been challenged after the discovery of specific recurrent chromosomal abnormalities. Multiple

  10. Variation of the mineral density in cortical bone may serve to keep strain amplitudes within a physiological range.

    Science.gov (United States)

    de Jong, W C; van Ruijven, L J; Brugman, P; Langenbach, G E J

    2013-08-01

    Within-bone variation in mineral density could be functional. A heterogeneous mineral-density distribution might serve to maintain habitual amplitudes of bone strain within a non-harmful, i.e., physiological range. Regions of a bone that would be strained the most on the basis of architecture alone might have a higher mineral density to make them more stiff and resistant to strain. We hypothesised that the cortical bone of the rabbit mandible contains such a functional distribution of mineral density. We thereby expected similar mineral-density patterns in the mandibles of different individuals due to the shared masticatory function. Secondly, we hypothesised that the highest mineral densities occur in mandibular regions predicted to be exposed to the largest amplitudes of strain-when taking into account bone architecture only. Mineral-density maps of the cortical bone of rabbit mandibles were obtained using micro-computed tomography (μCT). The μCT scans of two rabbits were converted into finite-element models (FEMs). To predict mandibular deformation during biting, these models were loaded by muscle forces and reaction forces. The forces acted on the condyles and on either the incisal or molar bite point. The FEMs were assigned a homogeneous material stiffness to calculate the strain amplitudes that would occur when only the architecture of the mandibular bone would be of influence. We found the cortical bone-mineral density patterns to be similar in all six mandibles. The mineral density of the corpus was higher than that of the ramus. A second consistent feature of the mandibular mineral-density distribution was that the medial ridge of the temporal-muscle insertion groove contained more mineral than its surrounding regions. The strain amplitudes calculated with the FEMs were variable and did not feature clear corpo-ramal differences. However, specific mandibular bone sites calculated to be exposed to the largest amplitudes of strain, including the medial

  11. Alveolar bone loss: mechanisms, potential therapeutic targets, and interventions.

    Science.gov (United States)

    Intini, G; Katsuragi, Y; Kirkwood, K L; Yang, S

    2014-05-01

    This article reviews recent research into mechanisms underlying bone resorption and highlights avenues of investigation that may generate new therapies to combat alveolar bone loss in periodontitis. Several proteins, signaling pathways, stem cells, and dietary supplements are discussed as they relate to periodontal bone loss and regeneration. RGS12 is a crucial protein that mediates osteoclastogenesis and bone destruction, and a potential therapeutic target. RGS12 likely regulates osteoclast differentiation through regulating calcium influx to control the calcium oscillation-NFATc1 pathway. A working model for RGS10 and RGS12 in the regulation of Ca(2+) oscillations during osteoclast differentiation is proposed. Initiation of inflammation depends on host cell-microbe interactions, including the p38 mitogen-activated protein kinase (MAPK) signaling pathway. Oral p38 inhibitors reduced lipopolysaccharide (LPS)-induced bone destruction in a rat periodontitis model but showed unsatisfactory safety profiles. The p38 substrate MK2 is a more specific therapeutic target with potentially superior tolerability. Furthermore, MKP-1 shows anti-inflammatory activity, reducing inflammatory cytokine biosynthesis and bone resorption. Multipotent skeletal stem cell (SSC) populations exist within the bone marrow and periosteum of long bones. These bone-marrow-derived SSCs and periosteum-derived SSCs have shown therapeutic potential in several applications, including bone and periodontal regeneration. The existence of craniofacial bone-specific SSCs is suggested based on existing studies. The effects of calcium, vitamin D, and soy isoflavone supplementation on alveolar and skeletal bone loss in post-menopausal women were investigated. Supplementation resulted in stabilization of forearm bone mass density and a reduced rate of alveolar bone loss over 1 yr, compared with placebo. Periodontal attachment levels were also well-maintained and alveolar bone loss suppressed during 24 wk of

  12. Comparison of lyophilization, and freezing in honey as techniques to preserve cortical bone allografts used to repair experimental femoral defects in domestic adult cats

    Directory of Open Access Journals (Sweden)

    M.P. Ferreira

    2012-04-01

    Full Text Available Cats with orthopedic conditions are a prominent part of the clinical work of veterinary. Conditions such as comminuted fractures, bone tumors and non-unions are often difficult to repair and may require the use of bone grafts for treatment. This study evaluated cortical bone allografts preserved in honey, frozen or lyophilized for correcting long bone defects created in the diaphysis of the right femur of domestic cats (n=24. In the control group (n=6, the defect was repaired using autogenous cortical bone graft. In the remaining animals (n=6/group, the defect was repaired with cortical bone allografts preserved in honey, frozen or lyophilized. Success of graft incorporation and length of time for consolidation were assessed through clinical, radiographic and histological evaluations performed up to 180 days. In the control, frozen, honey and lyophylized groups, respectively, success of graft incorporation was 91.6%, 83.3%, 75%, and 25%, with corresponding mean length of time for consolidation of 83.1, 78, 105 and 120 days. Incorporation percentage in the lyophilized group was significantly lower than in the frozen and control groups. In conclusion, bone grafts preserved in honey or frozen were effective for repairing cortical defects in the femurs of cats as compared to autogenous cortical bone grafts.

  13. Preliminary determination of calcium, phosphorus, and the calcium/phosphorus ratio in cortical bone of Chinstrap penguin using synchrotron X-ray fluorescence analysis

    Institute of Scientific and Technical Information of China (English)

    Xie Zhouqing; Cheng Bangbo; Sun Liguang; Huang Yuying; He Wei; Zhao Sanping

    2006-01-01

    Synchrotron radiation X-ray fluorescence (SR-XRF) approach was applied to analyzing of Chinstrap penguin (Pygoscelis Antarctica) cortical bone. The method enabled the in situ determination of Ca and P concentrations and the Ca/P ratio in cortical bone. The preliminary results show that: (1) there is the bone site-related difference for Ca and P concentrations. The mean values for the investigated parameters ( on a dry-weight basis) are: 30.7% (Ca) and 14.9% (P) for the femoral cortical bone, 21.4% (Ca) and 11.5% (P) for wing cortical bone. (2) The variation for the Ca/P ratio in cortical bone is lower than those for Ca and P separately.This is in agreement with the previous report that the specificity of the Ca/P ratio is better than that of Ca and P concentrations and is more reliable for the diagnosis of bone disorders. The authors suggest that further studies be conducted to establish normal values of Ca, P and Ca/P ratio for polar animals and provide a basis for the diagnosis of bone disorders.

  14. Long-term results of the use of autogenous cortical bone columellas to replace the stapes at stapedectomy.

    Science.gov (United States)

    Bauer, Miklós; Pytel, József; Vóna, Ida; Gerlinger, Imre

    2011-05-01

    The first author has been using an autogenous cortical bone columella to replace the stapes removed during stapedectomy since 1965. The audiograms of 21 of the 271 patients operated on with this method between 1965 and 1989 (i.e. 7.7% of the possible candidates) were available 20-35 (average 26.8) years postoperatively. The operation could be regarded as successful in 20 and unsuccessful in 1 patient in the long run. The audiological data are presented individually as averages of the values obtained at 0.5, 1, 2 and 3 kHz. The averaged data (n = 21): preoperative air conduction, 58.27; bone conduction, 24.46; and air-bone gap, 33.81 dB. Postoperative best air conduction, 19.07; bone conduction, 14.10; and air-bone gap, 4.97 dB. Postoperative recent air conduction, 45.77; bone conduction, 38.45; and air-bone gap, 7.32 dB. The best values were measured 1-8 (average 1.57) years postoperatively. In relation to the postoperative best value, the recent value of the air-bone gap had deteriorated by 2.35 dB, and that of the bone conduction by 24.35 dB. The small air-bone gap indicates that the deterioration of the hearing is mainly caused by the deterioration of the function of the inner ear and not by that of the conductive apparatus. The progression of the deterioration differs individually (0.3-1.6, average 0.93 dB/year) and accelerates with age. This finding seems to be a problem that does not depend on the operative technique. The data show that the autogenous bone columella ensures the same good and lasting results as the alloplastic solutions; moreover, there is no problem with the incus-prosthesis connection.

  15. Spatiotemporal analysis of the cortical sources of the steady-state visual evoked potential.

    Science.gov (United States)

    Di Russo, Francesco; Pitzalis, Sabrina; Aprile, Teresa; Spitoni, Grazia; Patria, Fabiana; Stella, Alessandra; Spinelli, Donatella; Hillyard, Steven A

    2007-04-01

    This study aimed to characterize the neural generators of the steady-state visual evoked potential (SSVEP) to repetitive, 6 Hz pattern-reversal stimulation. Multichannel scalp recordings of SSVEPs and dipole modeling techniques were combined with functional magnetic resonance imaging (fMRI) and retinotopic mapping in order to estimate the locations of the cortical sources giving rise to the SSVEP elicited by pattern reversal. The time-varying SSVEP scalp topography indicated contributions from two major cortical sources, which were localized in the medial occipital and mid-temporal regions of the contralateral hemisphere. Colocalization of dipole locations with fMRI activation sites indicated that these two major sources of the SSVEP were located in primary visual cortex (V1) and in the motion sensitive (MT/V5) areas, respectively. Minor contributions from mid-occipital (V3A) and ventral occipital (V4/V8) areas were also considered. Comparison of SSVEP phase information with timing information collected in a previous transient VEP study (Di Russo et al. [2005] Neuroimage 24:874-886) suggested that the sequence of cortical activation is similar for steady-state and transient stimulation. These results provide a detailed spatiotemporal profile of the cortical origins of the SSVEP, which should enhance its use as an efficient clinical tool for evaluating visual-cortical dysfunction as well as an investigative probe of the cortical mechanisms of visual-perceptual processing.

  16. 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.

  17. The estrogen receptor-alpha in osteoclasts mediates the protective effects of estrogens on cancellous but not cortical bone.

    Science.gov (United States)

    Martin-Millan, Marta; Almeida, Maria; Ambrogini, Elena; Han, Li; Zhao, Haibo; Weinstein, Robert S; Jilka, Robert L; O'Brien, Charles A; Manolagas, Stavros C

    2010-02-01

    Estrogens attenuate osteoclastogenesis and stimulate osteoclast apoptosis, but the molecular mechanism and contribution of these effects to the overall antiosteoporotic efficacy of estrogens remain controversial. We selectively deleted the estrogen receptor (ER)alpha from the monocyte/macrophage cell lineage in mice (ERalpha(LysM)(-/-)) and found a 2-fold increase in osteoclast progenitors in the marrow and the number of osteoclasts in cancellous bone, along with a decrease in cancellous bone mass. After loss of estrogens these mice failed to exhibit the expected increase in osteoclast progenitors, the number of osteoclasts in bone, and further loss of cancellous bone. However, they lost cortical bone indistinguishably from their littermate controls. Mature osteoclasts from ERalpha(LysM)(-/-) were resistant to the proapoptotic effect of 17beta-estradiol. Nonetheless, the effects of estrogens on osteoclasts were unhindered in mice bearing an ERalpha knock-in mutation that prevented binding to DNA. Moreover, a polymeric form of estrogen that is not capable of stimulating the nuclear-initiated actions of ERalpha was as effective as 17beta-estradiol in inducing osteoclast apoptosis in cells with the wild-type ERalpha. We conclude that estrogens attenuate osteoclast generation and life span via cell autonomous effects mediated by DNA-binding-independent actions of ERalpha. Elimination of these effects is sufficient for loss of bone in the cancellous compartment in which complete perforation of trabeculae by osteoclastic resorption precludes subsequent refilling of the cavities by the bone-forming osteoblasts. However, additional effects of estrogens on osteoblasts, osteocytes, and perhaps other cell types are required for their protective effects on the cortical compartment, which constitutes 80% of the skeleton.

  18. Eldecalcitol improves mechanical strength of cortical bones by stimulating the periosteal bone formation in the senescence-accelerated SAM/P6 mice - a comparison with alfacalcidol.

    Science.gov (United States)

    Shiraishi, Ayako; Sakai, Sadaoki; Saito, Hitoshi; Takahashi, Fumiaki

    2014-10-01

    Eldecalcitol (ELD), a 2β-hydroxypropyloxy derivative of 1α,25(OH)2D3, is a potent inhibitor of bone resorption that has demonstrated a greater effect at reducing the risk of fracture in osteoporotic patients than alfacalcidol (ALF). In the present study, we used the senescence-accelerated mouse strain P6 (SAM/P6), which has low bone mass caused by osteoblast dysfunction, to evaluate the effect of ELD on cortical bone in comparison with ALF. Four-month-old SAM/P6 mice were given either ELD (0.025 or 0.05μg/kg) or ALF (0.2 or 0.4μg/kg) by oral gavage 5 times/week for 6 weeks. Both ELD and ALF increased serum calcium (Ca) in a dose-dependent manner. Serum Ca levels in the ELD 0.05μg/kg group were comparable to those of the ALF 0.2μg/kg group. ELD 0.05μg/kg significantly improved the bone biomechanical properties of the femur compared with the vehicle control group (pBone histomorphometry revealed that in the femoral endocortical surface, the suppression of bone resorption parameters (N.Oc/BS) and bone formation parameters (MS/BS) by ELD (0.05μg/kg) was greater than that by ALF (0.2μg/kg). In contrast, in the femoral periosteal surface, ELD 0.05μg/kg significantly increased bone formation parameters (BFR/BS, MS/BS) compared with the vehicle control group (pbone not only by inhibiting endocortical bone resorption but also by stimulating the periosteal bone formation in SAM/P6 mice. This article is part of a Special Issue entitled '16th Vitamin D Workshop'.

  19. Preliminary estimates of the calcium/phosphorus ratio at different cortical bone sites using synchrotron microCT

    Science.gov (United States)

    Tzaphlidou, M.; Speller, R.; Royle, G.; Griffiths, J.

    2006-04-01

    The Ca/P ratio was measured in cortical bone samples from the femoral neck, front and rear tibia of female rats (1.5 years of age), using synchrotron radiation microtomography. The use of a monoenergetic x-ray beam, as provided by the synchrotron facility, generates accurate 3D maps of the linear attenuation coefficient within the sample and hence gives the ability to map different chemical components. Data sets were taken at 20 keV for each bone sample and calibration phantoms. From the 3D data sets, multiple 2D slices were reconstructed with a slice thickness of ~28 µm and converted to Ca/P ratios using the calibration phantom results. Mean values (M ± SD) for cortical femoral, front and rear tibias are 2.12 ± 0.08, 1.75 ± 0.06 and 1.94 ± 0.07 respectively. These values were compared with those derived from different animals. Differences between the same bone sites from different animals are not significant (0.1 life style and bone use.

  20. Design and Fabrication of 3D printed Scaffolds with a Mechanical Strength Comparable to Cortical Bone to Repair Large Bone Defects.

    Science.gov (United States)

    Roohani-Esfahani, Seyed-Iman; Newman, Peter; Zreiqat, Hala

    2016-01-19

    A challenge in regenerating large bone defects under load is to create scaffolds with large and interconnected pores while providing a compressive strength comparable to cortical bone (100-150 MPa). Here we design a novel hexagonal architecture for a glass-ceramic scaffold to fabricate an anisotropic, highly porous three dimensional scaffolds with a compressive strength of 110 MPa. Scaffolds with hexagonal design demonstrated a high fatigue resistance (1,000,000 cycles at 1-10 MPa compressive cyclic load), failure reliability and flexural strength (30 MPa) compared with those for conventional architecture. The obtained strength is 150 times greater than values reported for polymeric and composite scaffolds and 5 times greater than reported values for ceramic and glass scaffolds at similar porosity. These scaffolds open avenues for treatment of load bearing bone defects in orthopaedic, dental and maxillofacial applications.

  1. Design and Fabrication of 3D printed Scaffolds with a Mechanical Strength Comparable to Cortical Bone to Repair Large Bone Defects

    Science.gov (United States)

    Roohani-Esfahani, Seyed-Iman; Newman, Peter; Zreiqat, Hala

    2016-01-01

    A challenge in regenerating large bone defects under load is to create scaffolds with large and interconnected pores while providing a compressive strength comparable to cortical bone (100–150 MPa). Here we design a novel hexagonal architecture for a glass-ceramic scaffold to fabricate an anisotropic, highly porous three dimensional scaffolds with a compressive strength of 110 MPa. Scaffolds with hexagonal design demonstrated a high fatigue resistance (1,000,000 cycles at 1–10 MPa compressive cyclic load), failure reliability and flexural strength (30 MPa) compared with those for conventional architecture. The obtained strength is 150 times greater than values reported for polymeric and composite scaffolds and 5 times greater than reported values for ceramic and glass scaffolds at similar porosity. These scaffolds open avenues for treatment of load bearing bone defects in orthopaedic, dental and maxillofacial applications.

  2. Vitamin D and bone health: potential mechanisms.

    Science.gov (United States)

    Laird, Eamon; Ward, Mary; McSorley, Emeir; Strain, J J; Wallace, Julie

    2010-07-01

    Osteoporosis is associated with increased morbidity, mortality and significant economic and health costs. Vitamin D is a secosteriod hormone essential for calcium absorption and bone mineralization which is positively associated with bone mineral density [BMD]. It is well-established that prolonged and severe vitamin D deficiency leads to rickets in children and osteomalacia in adults. Sub-optimal vitamin D status has been reported in many populations but it is a particular concern in older people; thus there is clearly a need for effective strategies to optimise bone health. A number of recent studies have suggested that the role of vitamin D in preventing fractures may be via its mediating effects on muscle function (a defect in muscle function is one of the classical signs of rickets) and inflammation. Studies have demonstrated that vitamin D supplementation can improve muscle strength which in turn contributes to a decrease in incidence of falls, one of the largest contributors to fracture incidence. Osteoporosis is often considered to be an inflammatory condition and pro-inflammatory cytokines have been associated with increased bone metabolism. The immunoregulatory mechanisms of vitamin D may thus modulate the effect of these cytokines on bone health and subsequent fracture risk. Vitamin D, therefore, may influence fracture risk via a number of different mechanisms.

  3. Vitamin D and Bone Health; Potential Mechanisms

    Directory of Open Access Journals (Sweden)

    J.J. Strain

    2010-07-01

    Full Text Available Osteoporosis is associated with increased morbidity, mortality and significant economic and health costs. Vitamin D is a secosteriod hormone essential for calcium absorption and bone mineralization which is positively associated with bone mineral density [BMD]. It is well-established that prolonged and severe vitamin D deficiency leads to rickets in children and osteomalacia in adults. Sub-optimal vitamin D status has been reported in many populations but it is a particular concern in older people; thus there is clearly a need for effective strategies to optimise bone health. A number of recent studies have suggested that the role of vitamin D in preventing fractures may be via its mediating effects on muscle function (a defect in muscle function is one of the classical signs of rickets and inflammation. Studies have demonstrated that vitamin D supplementation can improve muscle strength which in turn contributes to a decrease in incidence of falls, one of the largest contributors to fracture incidence. Osteoporosis is often considered to be an inflammatory condition and pro-inflammatory cytokines have been associated with increased bone metabolism. The immunoregulatory mechanisms of vitamin D may thus modulate the effect of these cytokines on bone health and subsequent fracture risk. Vitamin D, therefore, may influence fracture risk via a number of different mechanisms.

  4. Bone lead (Pb) content at the tibia is associated with thinner distal tibia cortices and lower volumetric bone density in postmenopausal women.

    Science.gov (United States)

    Wong, Andy K O; Beattie, Karen A; Bhargava, Aakash; Cheung, Marco; Webber, Colin E; Chettle, David R; Papaioannou, Alexandra; Adachi, Jonathan D

    2015-10-01

    Conflicting evidence suggests that bone lead or blood lead may reduce areal bone mineral density (BMD). Little is known about how lead at either compartment affects bone structure. This study examined postmenopausal women (N=38, mean age 76 ± 8, body mass index (BMI): 26.74 ± 4.26 kg/m(2)) within the Hamilton cohort of the Canadian Multicentre Osteoporosis Study (CaMos), measuring bone lead at 66% of the non-dominant leg and at the calcaneus using (109)Cadmium X-ray fluorescence. Volumetric BMD and structural parameters were obtained from peripheral quantitative computed tomography images (200 μm in-plane resolution, 2.3 ± 0.5mm slice thickness) of the same 66% site and of the distal 4% site of the tibia length. Blood lead was measured using atomic absorption spectrometry and blood-to-bone lead partition coefficients (PBB, log ratio) were computed. Multivariable linear regression examined each of bone lead at the 66% tibia, calcaneus, blood lead and PBB as related to each of volumetric BMD and structural parameters, adjusting for age and BMI, diabetes or antiresorptive therapy. Regression coefficients were reported along with 95% confidence intervals. Higher amounts of bone lead at the tibia were associated with thinner distal tibia cortices (-0.972 (-1.882, -0.061) per 100 μg Pb/g of bone mineral) and integral volumetric BMD (-3.05 (-6.05, -0.05) per μg Pb/g of bone mineral). A higher PBB was associated with larger trabecular separation (0.115 (0.053, 0.178)), lower trabecular volumetric BMD (-26.83 (-50.37, -3.29)) and trabecular number (-0.08 (-0.14, -0.02)), per 100 μg Pb/g of bone mineral after adjusting for age and BMI, and remained significant while accounting for diabetes or use of antiresorptives. Total lead exposure activities related to bone lead at the calcaneus (8.29 (0.11, 16.48)) and remained significant after age and antiresorptives-adjustment. Lead accumulated in bone can have a mild insult on bone structure; but greater partitioning of lead

  5. Warm body temperature facilitates energy efficient cortical action potentials.

    Directory of Open Access Journals (Sweden)

    Yuguo Yu

    Full Text Available The energy efficiency of neural signal transmission is important not only as a limiting factor in brain architecture, but it also influences the interpretation of functional brain imaging signals. Action potential generation in mammalian, versus invertebrate, axons is remarkably energy efficient. Here we demonstrate that this increase in energy efficiency is due largely to a warmer body temperature. Increases in temperature result in an exponential increase in energy efficiency for single action potentials by increasing the rate of Na(+ channel inactivation, resulting in a marked reduction in overlap of the inward Na(+, and outward K(+, currents and a shortening of action potential duration. This increase in single spike efficiency is, however, counterbalanced by a temperature-dependent decrease in the amplitude and duration of the spike afterhyperpolarization, resulting in a nonlinear increase in the spike firing rate, particularly at temperatures above approximately 35°C. Interestingly, the total energy cost, as measured by the multiplication of total Na(+ entry per spike and average firing rate in response to a constant input, reaches a global minimum between 37-42°C. Our results indicate that increases in temperature result in an unexpected increase in energy efficiency, especially near normal body temperature, thus allowing the brain to utilize an energy efficient neural code.

  6. Bidirectional axial transmission can improve accuracy and precision of ultrasonic velocity measurement in cortical bone: a validation on test materials.

    Science.gov (United States)

    Bossy, Emmanuel; Talmant, Maryline; Defontaine, Marielle; Patat, Frédéric; Laugier, Pascal

    2004-01-01

    The axial transmission technique uses a linear arrangement of ultrasonic emitters and receivers placed on a same side of a cortical bone site in contact with the skin, involving ultrasonic propagation along the axis of bone. The velocity of the waves radiated from bone has been shown to reflect bone status. The thickness and composition of soft tissue may vary along the length of the bone, between different skeletal sites, or between subjects. Hence, accurate estimates of velocity require first to eliminate the effect of the overlying soft tissue that is traversed by the ultrasound wave. To correct for such bias without measuring soft tissue properties, we designed new ultrasonic probes in the 1-2 MHz frequency range. It is based on propagation along the bone surface in two opposite directions from two sources placed on both sides of a unique group of receivers. The aim is to obtain an unbiased estimate of the velocity without any intermediate calculation of soft tissue properties, such as thickness variation or velocity. Validation tests were performed on academic material such as Perspex or aluminum. We found that head wave velocity values could be biased by more than 10% for inclination of a few degrees between the test specimen surface and the probe. On test materials, the compensation procedure implemented in our probe led to a relative precision error on velocity measurement lower than 0.2 to 0.3%. These results suggest that the correction procedure allows measuring in vivo velocities independently of soft tissue properties.

  7. Slow pre-movement cortical potentials do not reflect individual response to therapy in writer's cramp

    DEFF Research Database (Denmark)

    Zeuner, K E; Peller, M; Knutzen, A

    2009-01-01

    OBJECTIVE: To investigate whether movement-related cortical potentials (MRCP) provide a physiological correlate that indicates the response to treatment in patients with writer's cramp. METHODS: In 21 patients with writer's cramp, who underwent 4 weeks of limb immobilization followed by re-traini...

  8. Cortico-cortical evoked potentials for sites of early versus late seizure spread in stereoelectroencephalography.

    Science.gov (United States)

    Lega, Bradley; Dionisio, Sasha; Flanigan, Patrick; Bingaman, William; Najm, Imad; Nair, Dileep; Gonzalez-Martinez, Jorge

    2015-09-01

    Cortico-cortical evoked potentials offer the possibility of understanding connectivity within seizure networks to improve diagnosis and more accurately identify candidates for seizure surgery. We sought to determine if cortico-cortical evoked potentials and post-stimulation oscillatory changes differ for sites of EARLY versus LATE ictal spread. 37 patients undergoing stereoelectroencephalography were tested using a cortico-cortical evoked potential paradigm. All electrodes were classified according to the speed of ictal spread. EARLY spread sites were matched to a LATE spread site equidistant from the onset zone. Root-mean-square was used to quantify evoked responses and post-stimulation gamma band power and coherence were extracted and compared. Sites of EARLY spread exhibited significantly greater evoked responses after stimulation across all patients (t(36)=2.973, p=0.004). Stimulation elicited enhanced gamma band activity at EARLY spread sites (t(36)=2.61, p=0.03, FDR corrected); this gamma band oscillation was highly coherent with the onset zone. Cortico-cortical evoked potentials and post-stimulation changes in gamma band activity differ between sites of EARLY versus LATE ictal spread. The oscillatory changes can help visualize connectivity within the seizure network.

  9. Compromised cortical bone compartment in type 2 diabetes mellitus patients with microvascular disease

    DEFF Research Database (Denmark)

    Shanbhogue, Vikram Vinod; Hansen, Stinus; Nielsen, Morten Frost Munk

    2016-01-01

    OBJECTIVE AND DESIGN: Patients with type 2 diabetes mellitus (T2D) have an increased fracture risk despite a normal or elevated bone mineral density (BMD). The aim of this cross-sectional in vivo study was to assess parameters of peripheral bone microarchitecture, estimated bone strength and bone......-resolution peripheral quantitative tomography (HR-pQCT) was used to assess bone structure at the non-dominant distal radius and tibia. Estimated bone strength was calculated using finite element analysis. Biochemical markers of bone turnover were measured in all participants. RESULTS: After adjusting for BMI, MVD...

  10. Finite element analysis of dental implant loading on atrophic and non-atrophic cancellous and cortical mandibular bone - a feasibility study.

    Science.gov (United States)

    Marcián, Petr; Borák, Libor; Valášek, Jiří; Kaiser, Jozef; Florian, Zdeněk; Wolff, Jan

    2014-12-18

    The first aim of this study was to assess displacements and micro-strain induced on different grades of atrophic cortical and trabecular mandibular bone by axially loaded dental implants using finite element analysis (FEA). The second aim was to assess the micro-strain induced by different implant geometries and the levels of bone-to-implant contact (BIC) on the surrounding bone. Six mandibular bone segments demonstrating different grades of mandibular bone atrophy and various bone volume fractions (from 0.149 to 0.471) were imaged using a micro-CT device. The acquired bone STL models and implant (Brånemark, Straumann, Ankylos) were merged into a three-dimensional finite elements structure. The mean displacement value for all implants was 3.1 ±1.2 µm. Displacements were lower in the group with a strong BIC. The results indicated that the maximum strain values of cortical and cancellous bone increased with lower bone density. Strain distribution is the first and foremost dependent on the shape of bone and architecture of cancellous bone. The geometry of the implant, thread patterns, grade of bone atrophy and BIC all affect the displacement and micro-strain on the mandible bone. Preoperative finite element analysis could offer improved predictability in the long-term outlook of dental implant restorations.

  11. Does the presence of tumor-induced cortical bone destruction at CT have any prognostic value in newly diagnosed diffuse large B-cell lymphoma?

    Energy Technology Data Exchange (ETDEWEB)

    Adams, Hugo J.A.; Nievelstein, Rutger A.J.; Kwee, Thomas C. [University Medical Center Utrecht, Department of Radiology and Nuclear Medicine, Utrecht (Netherlands); Klerk, John M.H. de [Meander Medical Center, Department of Nuclear Medicine, Amersfoort (Netherlands); Fijnheer, Rob [Meander Medical Center, Department of Hematology, Amersfoort (Netherlands); Heggelman, Ben G.F. [Meander Medical Center, Department of Radiology, Amersfoort (Netherlands); Dubois, Stefan V. [Meander Medical Center, Department of Pathology, Amersfoort (Netherlands)

    2015-05-01

    To determine the prognostic value of tumor-induced cortical bone destruction at computed tomography (CT) in newly diagnosed diffuse large B-cell lymphoma (DLBCL). This retrospective study included 105 patients with newly diagnosed DLBCL who had undergone CT and bone marrow biopsy (BMB) before R-CHOP (rituximab, cyclophosphamide, hydroxydaunorubicin, Oncovin, and prednisolone) chemo-immunotherapy. Cox regression analyses were used to determine the associations of cortical bone status at CT (absence vs. presence of tumor-induced cortical bone destruction), BMB findings (negative vs. positive for lymphomatous involvement), and dichotomized National Comprehensive Cancer Network International Prognostic Index (NCCN-IPI) strata (low risk vs. high risk) with progression-free survival (PFS) and overall survival (OS). Univariate Cox regression analysis indicated that cortical bone status at CT was no significant predictor of either PFS or OS (p = 0.358 and p = 0.560, respectively), whereas BMB findings (p = 0.002 and p = 0.013, respectively) and dichotomized NCCN-IPI risk strata (p = 0.002 and p = 0.003, respectively) were significant predictors of both PFS and OS. In the multivariate Cox proportional hazards model, only the dichotomized NCCN-IPI score was an independent predictive factor of PFS and OS (p = 0.004 and p = 0.003, respectively). The presence of tumor-induced cortical bone destruction at CT was not found to have any prognostic implications in newly diagnosed DLBCL. (orig.)

  12. Perlecan/Hspg2 deficiency alters the pericellular space of the lacunocanalicular system surrounding osteocytic processes in cortical bone.

    Science.gov (United States)

    Thompson, William R; Modla, Shannon; Grindel, Brian J; Czymmek, Kirk J; Kirn-Safran, Catherine B; Wang, Liyun; Duncan, Randall L; Farach-Carson, Mary C

    2011-03-01

    Osteocytes project long, slender processes throughout the mineralized matrix of bone, where they connect and communicate with effector cells. The interconnected cellular projections form the functional lacunocanalicular system, allowing fluid to pass for cell-to-cell communication and nutrient and waste exchange. Prevention of mineralization in the pericellular space of the lacunocanalicular pericellular space is crucial for uninhibited interstitial fluid movement. Factors contributing to the ability of the pericellular space of the lacunocanalicular system to remain open and unmineralized are unclear. Immunofluorescence and immunogold localization by transmission electron microscopy demonstrated perlecan/Hspg2 signal localized to the osteocyte lacunocanalicular system of cortical bone, and this proteoglycan was found in the pericellular space of the lacunocanalicular system. In this study we examined osteocyte lacunocanalicular morphology in mice deficient in the large heparan sulfate proteoglycan perlecan/Hspg2 in this tissue. Ultrastructural measurements with electron microscopy of perlecan/Hspg2-deficient mice demonstrated diminished osteocyte canalicular pericellular area, resulting from a reduction in the total canalicular area. Additionally, perlecan/Hspg2-deficient mice showed decreased canalicular density and a reduced number of transverse tethering elements per canaliculus. These data indicated that perlecan/Hspg2 contributed to the integrity of the osteocyte lacunocanalicular system by maintaining the size of the pericellular space, an essential task to promote uninhibited interstitial fluid movement in this mechanosensitive environment. This work thus identified a new barrier function for perlecan/Hspg2 in murine cortical bone.

  13. On the effect of x-ray irradiation on the deformation and fracture behavior of human cortical bone

    Energy Technology Data Exchange (ETDEWEB)

    Barth, Holly D.; Launey, Maximilien E.; McDowell, Alastair A.; Ager III, Joel W.; Ritchie, Robert O.

    2010-01-10

    In situ mechanical testing coupled with imaging using high-energy synchrotron x-ray diffraction or tomography imaging is gaining in popularity as a technique to investigate micrometer and even sub-micrometer deformation and fracture mechanisms in mineralized tissues, such as bone and teeth. However, the role of the irradiation in affecting the nature and properties of the tissue is not always taken into account. Accordingly, we examine here the effect of x-ray synchrotron-source irradiation on the mechanistic aspects of deformation and fracture in human cortical bone. Specifically, the strength, ductility and fracture resistance (both work-of-fracture and resistance-curve fracture toughness) of human femoral bone in the transverse (breaking) orientation were evaluated following exposures to 0.05, 70, 210 and 630 kGy irradiation. Our results show that the radiation typically used in tomography imaging can have a major and deleterious impact on the strength, post-yield behavior and fracture toughness of cortical bone, with the severity of the effect progressively increasing with higher doses of radiation. Plasticity was essentially suppressed after as little as 70 kGy of radiation; the fracture toughness was decreased by a factor of five after 210 kGy of radiation. Mechanistically, the irradiation was found to alter the salient toughening mechanisms, manifest by the progressive elimination of the bone's capacity for plastic deformation which restricts the intrinsic toughening from the formation 'plastic zones' around crack-like defects. Deep-ultraviolet Raman spectroscopy indicated that this behavior could be related to degradation in the collagen integrity.

  14. Radioscapholunate arthrodesis with distal excision of the distal scaphoid pole: Intraoperative measurement of range of motion and bone graft coming from a radial cortical flap

    Directory of Open Access Journals (Sweden)

    Cindy Bouvet

    2017-08-01

    Conclusions: Radioscapholunate arthrodesis in the case of radiocarpal arthritis with the use of a bone graft coming from the distal radius demonstrated robust results in terms of pain. The perioperative benefit on mobility was not found during postoperative period. A bone graft using a cortical cover from the distal radius yielded favorable results with regards to bone healing. [Hand Microsurg 2017; 6(2.000: 62-67

  15. Elevated Mechanical Loading When Young Provides Lifelong Benefits to Cortical Bone Properties in Female Rats Independent of a Surgically Induced Menopause

    Science.gov (United States)

    Galley, Matthew R.; Hurd, Andrea L.; Wallace, Joseph M.; Gallant, Maxime A.; Richard, Jeffrey S.; George, Lydia A.

    2013-01-01

    Exercise that mechanically loads the skeleton is advocated when young to enhance lifelong bone health. Whether the skeletal benefits of elevated loading when young persist into adulthood and after menopause are important questions. This study investigated the influence of a surgically induced menopause in female Sprague-Dawley rats on the lifelong maintenance of the cortical bone benefits of skeletal loading when young. Animals had their right forearm extrinsically loaded 3 d/wk between 4 and 10 weeks of age using the forearm axial compression loading model. Left forearms were internal controls and not loaded. Animals were subsequently detrained (restricted to cage activities) for 94 weeks (until age 2 years), with ovariectomy (OVX) or sham-OVX surgery being performed at 24 weeks of age. Loading enhanced midshaft ulna cortical bone mass, structure, and estimated strength. These benefits persisted lifelong and contributed to loaded ulnas having greater strength after detraining. Loading also had effects on cortical bone quality. The benefits of loading when young were not influenced by a surgically induced menopause because there were no interactions between loading and surgery. However, OVX had independent effects on cortical bone mass, structure, and estimated strength at early postsurgery time points (up to age 58 weeks) and bone quality measures. These data indicate skeletal loading when young had lifelong benefits on cortical bone properties that persisted independent of a surgically induced menopause. This suggests that skeletal loading associated with exercise when young may provide lifelong antifracture benefits by priming the skeleton to offset the cortical bone changes associated with aging and menopause. PMID:23782938

  16. Measurement of strain distribution in cortical bone around miniscrew implants used for orthodontic anchorage using digital speckle pattern interferometry

    Science.gov (United States)

    Kumar, Manoj; Agarwal, Rupali; Bhutani, Ravi; Shakher, Chandra

    2016-05-01

    An application of digital speckle pattern interferometry (DSPI) for the measurement of deformations and strain-field distributions developed in cortical bone around orthodontic miniscrew implants inserted into the human maxilla is presented. The purpose of this study is to measure and compare the strain distribution in cortical bone/miniscrew interface of human maxilla around miniscrew implants of different diameters, different implant lengths, and implants of different commercially available companies. The technique is also used to measure tilt/rotation of canine caused due to the application of retraction springs. The proposed technique has high sensitivity and enables the observation of deformation/strain distribution. In DSPI, two specklegrams are recorded corresponding to pre- and postloading of the retraction spring. The DSPI fringe pattern is observed by subtracting these two specklegrams. Optical phase was extracted using Riesz transform and the monogenic signal from a single DSPI fringe pattern. The obtained phase is used to calculate the parameters of interest such as displacement/deformation and strain/stress. The experiment was conducted on a dry human skull fulfilling the criteria of intact dental arches and all teeth present. Eight different miniscrew implants were loaded with an insertion angulation of 45 deg in the inter-radicular region of the maxillary second premolar and molar region. The loading of miniscrew implants was done with force level (150 gf) by nickel-titanium closed-coil springs (9 mm). The obtained results from DSPI reveal that implant diameter and implant length affect the displacement and strain distribution in cortical bone layer surrounding the miniscrew implant.

  17. Axono-cortical evoked potentials: A proof-of-concept study.

    Science.gov (United States)

    Mandonnet, E; Dadoun, Y; Poisson, I; Madadaki, C; Froelich, S; Lozeron, P

    2016-04-01

    Awake surgery is currently considered the best method to tailor intraparenchymatous resections according to functional boundaries. However, the exact mechanisms by which electrical stimulation disturbs behavior remain largely unknown. In this case report, we describe a new method to explore the propagation toward cortical sites of a brief pulse applied to an eloquent white matter pathway. We present a patient, operated on in awake condition for removal of a cavernoma of the left ventral premotor cortex. At the end of the resection, the application of 60Hz stimulation in the white matter of the operculum induced anomia. Stimulating the same site at a frequency of 1Hz during 70seconds allowed to record responses on electrodes put over Broca's area and around the inferior part of central sulcus. Axono-cortical evoked potentials were then obtained by averaging unitary responses, time-locked to the stimulus. We then discuss the origin of these evoked axono-cortical potentials and the likely pathway connecting the stimulation site to the recorded cortical sites.

  18. Giant early components of somatosensory evoked potentials to tibial nerve stimulation in cortical myoclonus.

    Science.gov (United States)

    Anzellotti, Francesca; Onofrj, Marco; Bonanni, Laura; Saracino, Antonio; Franciotti, Raffaella

    2016-01-01

    Enlarged cortical components of somatosensory evoked potentials (giant SEPs) recorded by electroencephalography (EEG) and abnormal somatosensory evoked magnetic fields (SEFs) recorded by magnetoencephalography (MEG) are observed in the majority of patients with cortical myoclonus (CM). Studies on simultaneous recordings of SEPs and SEFs showed that generator mechanism of giant SEPs involves both primary sensory and motor cortices. However the generator sources of giant SEPs have not been fully understood as only one report describes clearly giant SEPs following lower limb stimulation. In our study we performed a combined EEG-MEG recording on responses elicited by electric median and tibial nerve stimulation in a patient who developed consequently to methyl bromide intoxication CM with giant SEPs to median and tibial nerve stimuli. SEPs wave shapes were identified on the basis of polarity-latency components (e.g. P15-N20-P25) as defined by earlier studies and guidelines. At EEG recording, the SEP giant component did not appear in the latency range of the first cortical component for median nerve SEP (N20), but appeared instead in the range of the P37 tibial nerve SEP, which is currently identified as the first cortical component elicited by tibial nerve stimuli. Our MEG and EEG SEPs recordings also showed that components in the latency range of P37 were preceded by other cortical components. These findings suggest that lower limb P37 does not correspond to upper limb N20. MEG results confirmed that giant SEFs are the second component from both tibial (N43m-P43m) and median (N27m-P27m) nerve stimulation. MEG dipolar sources of these giant components were located in the primary sensory and motor area.

  19. The investigation of cortical auditory evoked potentials responses in young adults having musical education.

    Science.gov (United States)

    Polat, Zahra; Ataş, Ahmet

    2014-12-01

    In the literature, music education has been shown to enhance auditory perception for children and young adults. When compared to young adult non-musicians, young adult musicians demonstrate increased auditory processing, and enhanced sensitivity to acoustic changes. The evoked response potentials associated with the interpretation of sound are enhanced in musicians. Studies show that training also changes sound perception and cortical responses. The earlier training appears to lead to larger changes in the auditory cortex. Most cortical studies in the literature have used pure tones or musical instrument sounds as stimuli signals. The aim of those studies was to investigate whether musical education would enhance auditory cortical responses when speech signals were used. In this study, the speech sounds extracted from running speech were used as sound stimuli. Non-randomized controlled study. The experimental group consists of young adults up to 21 years-old, all with a minimum of 4 years of musical education. The control group was selected from young adults of the same age without any musical education. The experiments were conducted by using a cortical evoked potential analyser and /m/, /t/ /g/ sound stimulation at the level of 65 dB SPL. In this study, P1 / N1 / P2 amplitude and latency values were measured. Significant differences were found in the amplitude values of P1 and P2 (p0.05). The results obtained in our study indicate that musical experience has an effect on the nervous system and this can be seen in cortical auditory evoked potentials recorded when the subjects hear speech.

  20. The micro-damage process zone during transverse cortical bone fracture: No ears at crack growth initiation.

    Science.gov (United States)

    Willett, Thomas; Josey, David; Lu, Rick Xing Ze; Minhas, Gagan; Montesano, John

    2017-10-01

    Apply high-resolution benchtop micro-computed tomography (micro-CT) to gain greater understanding and knowledge of the formation of the micro-damage process zone formed during traverse fracture of cortical bone. Bovine cortical bone was cut into single edge notch (bending) fracture testing specimens with the crack on the transverse plane and oriented to grow in the circumferential direction. We used a multi-specimen technique and deformed the specimens to various individual secant modulus loss levels (P-values) up to and including maximum load (Pmax). Next, the specimens were infiltrated with a BaSO4 precipitation stain and scanned at 3.57-μm isotropic voxel size using a benchtop high resolution-micro-CT. Measurements of the micro-damage process zone volume, width and height were made. These were compared with the simple Irwin's process zone model and with finite element models. Electron and confocal microscopy confirmed the formation of BaSO4 precipitate in micro-cracks and other porosity, and an interesting novel mechanism similar to tunneling. Measurable micro-damage was detected at low P values and the volume of the process zone increased according to a second order polynomial trend. Both width and height grew linearly up to Pmax, at which point the process zone cross-section (perpendicular to the plane of the crack) was almost circular on average with a radius of approximately 550µm (approximately one quarter of the unbroken ligament thickness) and corresponding to the shape expected for a biological composite under plane stress conditions. This study reports details of the micro-damage fracture process zone previously unreported for cortical bone. High-resolution micro-CT enables 3D visualization and measurement of the process zone and confirmation that the crack front edge and process zone are affected by microstructure. It is clear that the process zone for the specimens studied grows to be meaningfully large, confirming the need for the J

  1. Intra- and inter-observer variation in histological criteria used in age at death determination based on femoral cortical bone

    DEFF Research Database (Denmark)

    Lynnerup, N; Thomsen, J L; Frohlich, B

    1998-01-01

    been carried out dealing with the intra- and inter-observer error. Furthermore, when such studies have been completed, the statistical tools for assessing variability have not been adequate. This study presents the results of applying simple quantitative statistics on several counts of microscopic...... elements as observed on photographic images of cortical bone, in order to assess intra- and inter-observer error. Overall, substantial error was present at the level of identifying and counting secondary osteons, osteon fragments and Haversian canals. Only secondary osteons can be reliably identified...

  2. Osteogenesis and angiogenesis: The potential for engineering bone

    Directory of Open Access Journals (Sweden)

    JM Kanczler

    2008-05-01

    Full Text Available The repair of large bone defects remains a major clinical orthopaedic challenge. Bone is a highly vascularised tissue reliant on the close spatial and temporal connection between blood vessels and bone cells to maintain skeletal integrity. Angiogenesis thus plays a pivotal role in skeletal development and bone fracture repair. Current procedures to repair bone defects and to provide structural and mechanical support include the use of grafts (autologous, allogeneic or implants (polymeric or metallic. These approaches face significant limitations due to insufficient supply, potential disease transmission, rejection, cost and the inability to integrate with the surrounding host tissue.The engineering of bone tissue offers new therapeutic strategies to aid musculoskeletal healing. Various scaffold constructs have been employed in the development of tissue-engineered bone; however, an active blood vessel network is an essential pre-requisite for these to survive and integrate with existing host tissue. Combination therapies of stem cells and polymeric growth factor release scaffolds tailored to promote angiogenesis and osteogenesis are under evaluation and development actively to stimulate bone regeneration. An understanding of the cellular and molecular interactions of blood vessels and bone cells will enhance and aid the successful development of future vascularised bone scaffold constructs, enabling survival and integration of bioengineered bone with the host tissue. The role of angiogenic and osteogenic factors in the adaptive response and interaction of osteoblasts and endothelial cells during the multi step process of bone development and repair will be highlighted in this review, with consideration of how some of these key mechanisms can be combined with new developments in tissue engineering to enable repair and growth of skeletal fractures. Elucidation of the processes of angiogenesis, osteogenesis and tissue engineering strategies offer

  3. 'Catching the waves' - slow cortical potentials as moderator of voluntary action.

    Science.gov (United States)

    Schmidt, Stefan; Jo, Han-Gue; Wittmann, Marc; Hinterberger, Thilo

    2016-09-01

    The readiness potential is an ongoing negativity in the EEG preceding a self-initiated movement by approximately 1.5s. So far it has predominantly been interpreted as a preparatory signal with a causal link to the upcoming movement. Here a different hypothesis is suggested which we call the selective slow cortical potential sampling hypothesis. In this review of recent research results we argue that the initiation of a voluntary action is more likely during negative fluctuations of the slow cortical potential and that the sampling and averaging of many trials leads to the observed negativity. That is, empirical evidence indicates that the early readiness potential is not a neural correlate of preconscious motor preparation and thus a determinant of action. Our hypothesis thereafter challenges the classic interpretation of the Libet experiment which is often taken as proof that there is no free will. We furthermore suggest that slow cortical potentials are related to an urge to act but are not a neural indicator of the decision process of action initiation.

  4. Membrane potential dynamics of populations of cortical neurons during auditory streaming

    Science.gov (United States)

    Farley, Brandon J.

    2015-01-01

    How a mixture of acoustic sources is perceptually organized into discrete auditory objects remains unclear. One current hypothesis postulates that perceptual segregation of different sources is related to the spatiotemporal separation of cortical responses induced by each acoustic source or stream. In the present study, the dynamics of subthreshold membrane potential activity were measured across the entire tonotopic axis of the rodent primary auditory cortex during the auditory streaming paradigm using voltage-sensitive dye imaging. Consistent with the proposed hypothesis, we observed enhanced spatiotemporal segregation of cortical responses to alternating tone sequences as their frequency separation or presentation rate was increased, both manipulations known to promote stream segregation. However, across most streaming paradigm conditions tested, a substantial cortical region maintaining a response to both tones coexisted with more peripheral cortical regions responding more selectively to one of them. We propose that these coexisting subthreshold representation types could provide neural substrates to support the flexible switching between the integrated and segregated streaming percepts. PMID:26269558

  5. Effect of cerebral lymphatic block on cerebral morphology and cortical evoked potential in rats

    Institute of Scientific and Technical Information of China (English)

    Zuoli Xia; Baoling Sun; Mingfeng Yang; Dongmei Hu; Tong Zhao; Jingzhong Niu

    2006-01-01

    BACKGROUND: It has been shown that although brain does not contain lining endothelial lymphatic vessel,it has lymphatic drain.Anterior lymphatic vessel in brain tissue plays a key role in introducing brain interstitial fluid to lymphatic system;however,the significance of lymphatic drain and the affect on cerebral edema remains unclear.OBJECTIVE: To investigate the effect of cerebral lymphatic block on cerebral morphology and cortical evoked potential in rats.DESIGN: Randomized controlled animal study.SETTING: Institute of Cerebral Microcirulation of Taishan Medical College and Department of Neurology of Affiliated Hospital.MATERIALS:A total of 63 healthy adult male Wistar rats weighing 300-350 g were selected in this study.Forty-seven rats were used for the morphological observation induced by lymphatic drain and randomly divided into three groups:general observation group(n=12),light microscopic observation group(n=21)and electronic microscopic observation group(n=14).The rats in each group were divided into cerebral lymphatic block subgroup and sham-operation control subgroup.Sixteen rats were divided into cerebral the effect of cerebral lymphatic block on cortical evoked potential,in which the animals were randomly divided into sham-operation group(n=6)and cerebral lymphatic block group(n=10).METHODS:The experiment was carried out in the Institute of Cerebral Microcirculation of Taishan Medical College from January to August 2003.Rats in cerebral lymphatic block group were anesthetized and separated bilateral superficial and deep cervical lymph nodes under sterile condition. Superior and inferior boarders of lymph nodes were ligated the inputting and outputting channels, respectively, and then lymph node was removed so as to establish cerebral lymphatic drain disorder models. Rats in sham-operation control group were not ligated the lymphatic vessel and removed lymph nodes.and other operations were as the same as those in cerebral lymphatic block group

  6. 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.

  7. Simulation of acoustic guided wave propagation in cortical bone using a semi-analytical finite element method.

    Science.gov (United States)

    Pereira, Daniel; Haiat, Guillaume; Fernandes, Julio; Belanger, Pierre

    2017-04-01

    Axial transmission techniques have been extensively studied for cortical bone quality assessment. However, the modeling of ultrasonic guided waves propagation in such a complex medium remains challenging. The aim of this paper is to develop a semi-analytical finite element method to simulate the propagation of guided waves in an irregular, multi-layer, and heterogeneous bone cross-section modeled with anisotropic and viscoelastic material properties. The accuracy of the simulations was verified against conventional time-domain three-dimensional finite element. The method was applied in the context of axial transmission in bone to investigate the feasibility of first arrival signal (FAS) to monitor degradation of intracortical properties at low frequency. Different physiopathological conditions for the intracortical region, varying from healthy to osteoporotic, were monitored through FAS velocity using a 10-cycle tone burst excitation centered at 32.5 kHz. The results show that the variation in FAS velocity is mainly associated with four of the eight modes supported by the waveguide, varying with velocity values between 550 and 700 m/s along the different scenarios. Furthermore, the FAS velocity is shown to be associated with the group velocity of the mode with the highest relative amplitude contribution at each studied scenario. However, because of the evolution of the mode with the highest contribution, the FAS velocity is shown to be limited to discriminate intracortical bone properties at low frequency.

  8. Eldecalcitol, a vitamin D analog, reduces bone turnover and increases trabecular and cortical bone mass, density, and strength in ovariectomized cynomolgus monkeys.

    Science.gov (United States)

    Smith, Susan Y; Doyle, Nancy; Boyer, Marilyne; Chouinard, Luc; Saito, Hitoshi

    2013-11-01

    Vitamin D insufficiency is common in elderly people worldwide, and intake of supplementary calcium and vitamin D is recommended to those with a high risk of fracture. Several clinical studies and meta-analyses have shown that calcium and vitamin D supplementation reduces osteoporotic fractures, and a strong correlation exists between vitamin D status and fracture risk. Vitamin D supplementations improve calcium balance in the body; however, it remains unclear whether vitamin D directly affects bone metabolism. Recently, eldecalcitol (ELD), an active form of vitamin D analog, has been approved for the treatment of osteoporosis in Japan. A 3-year clinical trial showed ELD treatment increased lumbar spine bone mineral density (BMD) and reduced fracture risk in patients with osteoporosis. To evaluate the mechanism of ELD action in bone remodeling, ovariectomized cynomolgus monkeys were treated with 0.1 or 0.3μg/day of ELD for 6months. This treatment increased lumbar BMD by 4.4% and 10.2%, respectively, and suppressed ovariectomy-induced increases in bone turnover markers compared to OVX-vehicle control. Histomorphometric analysis of bone revealed that both bone formation parameters and bone resorption parameters in the trabecular bone of the lumbar vertebrae were suppressed by ELD treatment. ELD treatment also improved biomechanical properties of the lumbar vertebrae and the femoral neck in the ovariectomized cynomolgus monkeys. These results indicate that, in a bone-remodeling animal model, ELD increases BMD and improves bone biomechanical properties by normalizing bone turnover. Therefore, ELD has a direct and potentially beneficial effect on bone metabolism. Copyright © 2013 The Authors. Published by Elsevier Inc. All rights reserved.

  9. Predicting Hip Fracture Type With Cortical Bone Mapping (CBM) in the Osteoporotic Fractures in Men (MrOS) Study.

    Science.gov (United States)

    Treece, Graham M; Gee, Andrew H; Tonkin, Carol; Ewing, Susan K; Cawthon, Peggy M; Black, Dennis M; Poole, Kenneth E S

    2015-11-01

    Hip fracture risk is known to be related to material properties of the proximal femur, but fracture prediction studies adding richer quantitative computed tomography (QCT) measures to dual-energy X-ray (DXA)-based methods have shown limited improvement. Fracture types have distinct relationships to predictors, but few studies have subdivided fracture into types, because this necessitates regional measurements and more fracture cases. This work makes use of cortical bone mapping (CBM) to accurately assess, with no prior anatomical presumptions, the distribution of properties related to fracture type. CBM uses QCT data to measure the cortical and trabecular properties, accurate even for thin cortices below the imaging resolution. The Osteoporotic Fractures in Men (MrOS) study is a predictive case-cohort study of men over 65 years old: we analyze 99 fracture cases (44 trochanteric and 55 femoral neck) compared to a cohort of 308, randomly selected from 5994. To our knowledge, this is the largest QCT-based predictive hip fracture study to date, and the first to incorporate CBM analysis into fracture prediction. We show that both cortical mass surface density and endocortical trabecular BMD are significantly different in fracture cases versus cohort, in regions appropriate to fracture type. We incorporate these regions into predictive models using Cox proportional hazards regression to estimate hazard ratios, and logistic regression to estimate area under the receiver operating characteristic curve (AUC). Adding CBM to DXA-based BMD leads to a small but significant (p fracture, with AUC increasing from 0.78 to 0.79, assessed using leave-one-out cross-validation. For specific fracture types, the improvement is more significant (p fractures and 0.76 to 0.82 for femoral neck fractures. In contrast, adding DXA-based BMD to a CBM-based predictive model does not result in any significant improvement. © 2015 The Authors. Journal of Bone and Mineral Research published by

  10. Characterization of the effects of x-ray irradiation on the hierarchical structure and mechanical properties of human cortical bone

    Energy Technology Data Exchange (ETDEWEB)

    Barth, Holly; Zimmermann, Elizabeth; Schaible, Eric; Tang, Simon; Alliston, Tamara; Ritchie, Robert

    2011-08-19

    Bone comprises a complex structure of primarily collagen, hydroxyapatite and water, where each hierarchical structural level contributes to its strength, ductility and toughness. These properties, however, are degraded by irradiation, arising from medical therapy or bone-allograft sterilization. We provide here a mechanistic framework for how irradiation affects the nature and properties of human cortical bone over a range of characteristic (nano to macro) length-scales, following x-­ray exposures up to 630 kGy. Macroscopically, bone strength, ductility and fracture resistance are seen to be progressively degraded with increasing irradiation levels. At the micron-­scale, fracture properties, evaluated using in-situ scanning electron microscopy and synchrotron x-ray computed micro-tomography, provide mechanistic information on how cracks interact with the bone-matrix structure. At sub-micron scales, strength properties are evaluated with in-situ tensile tests in the synchrotron using small-/wide-angle x-ray scattering/diffraction, where strains are simultaneously measured in the macroscopic tissue, collagen fibrils and mineral. Compared to healthy bone, results show that the fibrillar strain is decreased by ~40% following 70 kGy exposures, consistent with significant stiffening and degradation of the collagen. We attribute the irradiation-­induced deterioration in mechanical properties to mechanisms at multiple length-scales, including changes in crack paths at micron-­scales, loss of plasticity from suppressed fibrillar sliding at sub-­micron scales, and the loss and damage of collagen at the nano-­scales, the latter being assessed using Raman and Fourier-Transform-Infrared spectroscopy and a fluorometric assay.

  11. Accounting for beta-particle energy loss to cortical bone via paired-image radiation transport (PIRT).

    Science.gov (United States)

    Shah, Amish P; Rajon, Didier A; Patton, Phillip W; Jokisch, Derek W; Bolch, Wesley E

    2005-05-01

    Current methods of skeletal dose assessment in both medical physics (radionuclide therapy) and health physics (dose reconstruction and risk assessment) rely heavily on a single set of bone and marrow cavity chord-length distributions in which particle energy deposition is tracked within an infinite extent of trabecular spongiosa, with no allowance for particle escape to cortical bone. In the present study, we introduce a paired-image radiation transport (PIRT) model which provides a more realistic three-dimensional (3D) geometry for particle transport in the skeletal site at both microscopic and macroscopic levels of its histology. Ex vivo CT scans were acquired of the pelvis, cranial cap, and individual ribs excised from a 66-year male cadaver (BMI of 22.7 kg m(-2)). For the three skeletal sites, regions of trabecular spongiosa and cortical bone were identified and segmented. Physical sections of interior spongiosa were taken and subjected to microCT imaging. Voxels within the resulting microCT images were then segmented and labeled as regions of bone trabeculae, endosteum, active marrow, and inactive marrow through application of image processing algorithms. The PIRT methodology was then implemented within the EGSNRC radiation transport code whereby electrons of various initial energies are simultaneously tracked within both the ex vivo CT macroimage and the CT microimage of the skeletal site. At initial electron energies greater than 50-200 keV, a divergence in absorbed fractions to active marrow are noted between PIRT model simulations and those estimated under existing techniques of infinite spongiosa transport. Calculations of radionuclide S values under both methodologies imply that current chord-based models may overestimate the absorbed dose to active bone marrow in these skeletal sites by 0% to 27% for low-energy beta emitters (33P, 169Er, and 177Lu), by approximately 4% to 49% for intermediate-energy beta emitters (153Sm, 186Re, and 89Sr), and by

  12. Microstructural and Photoacoustic Infrared Spectroscopic Studies of Human Cortical Bone with Osteogenesis Imperfecta

    Science.gov (United States)

    Gu, Chunju; Katti, Dinesh R.; Katti, Kalpana S.

    2016-04-01

    The molecular basis of bone disease osteogenesis imperfecta (OI) and the mineralization of hydroxyapatite in OI bone have been of significant research interest. To further investigate the mechanism of OI disease and bone mineralization, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy, and x-ray diffraction (XRD) are used in the present study to describe the structural and compositional differences between OI and healthy bone. OI bone exhibits more porous, fibrous features, abnormal collagen fibrils, and abnormal mineral deposits. Likewise, photoacoustic-FTIR experiments indicate an aberrant collagen structure and an altered mineral structure in OI. In contrast, there is neither significant difference in the non-collagenous proteins (NCPs) composition observed nor apparent change in the crystal structure between OI and healthy bone minerals as shown in XRD and energy-dispersive x-ray spectroscopy (EDS) results. This observation indicates that the biomineralization process is more controlled by the bone cells and non-collagenous phosphorylated proteins. The present study also confirms that there is an orientational influence on the stoichiometry of the mineral in OI bone. Also, a larger volume of the hydrated layer in the transverse plane than the longitudinal plane of the mineral crystal structure is proposed. The appearance of a new C-S band in the FTIR spectra in OI bone suggests the substitution of glycine by cysteine in collagen molecules or/and an increased amount of cysteine-rich osteonectin that relates to mineral nucleation and mineral crystal formation.

  13. Correlation between longitudinal, circumferential, and radial moduli in cortical bone: effect of mineral content.

    Science.gov (United States)

    Macione, J; Depaula, C A; Guzelsu, N; Kotha, S P

    2010-07-01

    Previous studies indicate that changes in the longitudinal elastic properties of bone due to changes in mineral content are related to the longitudinal strength of bone tissue. Changes in mineral content are expected to affect bone tissue mechanical properties along all directions, albeit to different extents. However, changes in tissue mechanical properties along the different directions are expected to be correlated to one another. In this study, we investigate if radial, circumferential, and longitudinal moduli are related in bone tissue with varying mineral content. Plexiform bovine femoral bone samples were treated in fluoride ion solutions for a period of 3 and 12 days to obtain bones with 20% and 32% lower effective mineral contents. Transmission ultrasound velocities were obtained in the radial, circumferential, and longitudinal axes of bone and combined with measured densities to obtain corresponding tensorial moduli. Results indicate that moduli decreased with fluoride ion treatments and were significantly correlated to one another (r(2) radial vs. longitudinal = 0.80, r(2) circumferential vs. longitudinal = 0.90, r(2) radial vs. circumferential = 0.85). Densities calculated from using ultrasound parameters, acoustic impedance and transmission velocities, were moderately correlated to those measured by the Archimedes principle (r(2)=0.54, p<0.01). These results suggest that radial and circumferential ultrasound measurements could be used to determine the longitudinal properties of bone and that ultrasound may not be able to predict in vitro densities of bones containing unbonded mineral. Published by Elsevier Ltd.

  14. 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

  15. The locus of color sensation: Cortical color loss and the chromatic visual evoked potential

    Science.gov (United States)

    Crognale, Michael A.; Duncan, Chad S.; Shoenhard, Hannah; Peterson, Dwight J.; Berryhill, Marian E.

    2013-01-01

    Color losses of central origin (cerebral achromatopsia and dyschromatopsia) can result from cortical damage and are most commonly associated with stroke. Such cases have the potential to provide useful information regarding the loci of the generation of the percept of color. One available tool to examine this issue is the chromatic visual evoked potential (cVEP). The cVEP has been used successfully to objectively quantify losses in color vision capacity in both congenital and acquired deficiencies of retinal origin but has not yet been applied to cases of color losses of cortical origin. In addition, it is not known with certainty which cortical sites are responsible for the generation of the cVEP waveform components. Here we report psychophysical and electrophysiological examination of a patient with color deficits resulting from a bilateral cerebral infarct in the ventral occipitotemporal region. Although this patient demonstrated pronounced color losses of a general nature, the waveform of the cVEP remains unaffected. Contrast response functions of the cVEP are also normal for this patient. The results suggest that the percept of color arises after the origin of the cVEP and that normal activity in those areas that give rise to the characteristic negative wave of the cVEP are not sufficient to provide for the normal sensation of color. PMID:23986535

  16. Histopathological and Histomorphometrical Effects of Atorvastatin on Experimental Femoral Cortical Bone Defect Healing in Rats

    Directory of Open Access Journals (Sweden)

    M Valilu

    2012-05-01

    Full Text Available Background: Bone remodeling has always been the goal of surgeons for a long time. Recently, it was shown that statins that are commonly prescribed for lowering cholesterol also have beneficial effects on bone healing. Therefore, the present study was undertaken to evaluate the probable effects of atorvastatin on osteogenesis in the rat femur. Methods: This experimental study was conducted on 30 male Sprague-Dawley (SD rats. The animals were divided randomly into one control and two experiment groups. After induction of anesthesia, a hole of 2 mm in diameter was made in femur width. The control group received physiological serum but the experiment groups one and two, respectively, received 10 and 20 mg/kg/PO of atorvastatin on daily basis. After euthanizing the rats, histopathological and histomorphometrical evaluations of the bones were performed 45 days after the intervention. Results: In the control group, the defects seemed to be filled with woven bone and bone marrow, depictive of a poor osteogenic activity. In the experiment groups, many osteoblast groupings and young bone trabeculae had been formed and bone trabeculae were more organized. Histomorphometric results, showed that atorvastatin had significantly promoted bone healing in the experiment groups compared with the controls (P<0.001. Moreover, the analysis showed that atorvastatin had more significant effects in group three receiving high doses of the medication in comparison with group two (P<0.001. Conclusion: The findings of this study showed that atorvastatin is capable of stimulating osteogenesis in rats.

  17. Effect of risedronate on the cortical and cancellous bone mass and mechanical properties in ovariectomized rats: a comparison with the effects of alfacalcidol.

    Science.gov (United States)

    Iwamoto, Jun; Seki, Azusa; Takeda, Tsuyoshi; Sato, Yoshihiro; Yamada, Harumoto; Yeh, James K

    2006-12-01

    The purpose of the present study was to compare the effects of risedronate (RIS) and alfacalcidol (ALF) on the cortical and cancellous bone mass and mechanical properties in ovariectomized rats in a head-to-head fashion. Forty female Sprague-Dawley rats, 7 mo of age, were randomized into six groups: the sham-operated control (Sham) group, and five ovariectomized groups: treated with vehicle, RIS (0.1, 1.0, or 2.5 mg/kg, p.o., daily), and ALF (0.5 microg/kg, p.o., daily). At the end of the 8-wk experimental period, bone histomorphometric analyses of the cancellous bone of the proximal tibial metaphysis and cortical bone of the tibial disphysis was performed, and the mechanical properties of the bone were evaluated at the femoral distal metaphysis (FDM) and femoral diaphysis (FD). RIS prevented the decrease in the cancellous bone volume/total tissue volume (BV/TV) noted in ovariectomized rats in a dose-dependent manner, by suppressing increases in cancellous bone formation and resorption, without any apparent effect on the Ct Ar or maximum load of the FDM or FD. On the other hand, ALF increased the cancellous BV/TV, Ct Ar, and maximum load of the FDM or FD, by mildly decreasing cancellous bone formation and resorption, increasing periosteal and endocortical bone formation, and preventing an increase in endocortical bone resorption. Thus, the present study clearly showed that RIS and ALF had differential effects on the cortical and cancellous bone mass and mechanical properties in ovariectomized rats.

  18. Cortical field potentials associated with audio-initiated vocalization in monkeys.

    Science.gov (United States)

    Gemba, H; Kyuhou, S; Matsuzaki, R; Amino, Y

    1999-09-03

    Five monkeys vocalizing at self-pace (self-paced vocalization) were well trained to vocalize in response to a monkey call (audio-initiated vocalization). Field potentials associated with audio-initiated vocalizations were recorded by using electrodes which were implanted chronically on the surface and at a 2.0-3.0 mm depth in various cortical areas. A surface-negative (s-N), depth-positive (d-P) potential (at about 70 ms latency after stimulus onset) was recorded in the rostral bank of the inferior limb of the arcuate sulcus in the left hemisphere, in which an insignificant potential was associated with self-paced vocalizations. An s-N, d-P slow potential which occurred in the motor and somatosensory cortices with a latency of about 300 ms after stimulus, started about 700 ms before vocalizations. The duration and amplitude of this potential was substantially the same with those of the potential which occurred with self-paced vocalizations. Reaction times from stimulus onset to vocalization start were variable, but were about 0.9s on the average. The findings were discussed in connection with reaction-time hand movements.

  19. Cortical evoked potentials in response to rapid balloon distension of the rectum and anal canal

    DEFF Research Database (Denmark)

    Haas, S; Brock, C; Krogh, K

    healthy women received 30 RBDs in the rectum and the anal canal at intensities corresponding to sensory and unpleasantness thresholds, and response was recorded as cortical evoked potentials (CEPs) in 64-channels. The anal canal stimulations at unpleasantness level were repeated after 4 min to test...... showed reproducibility with ICCs for all bands >0.8 and corresponding CVs potentials evoked from the anal canal are challenged by latency jitter likely related to variability in muscle tone due to the distensions. Using single-sweep analysis, anal CEPs proved...

  20. Age-related changes in the plasticity and toughness of human cortical bone at multiple length-scales

    Energy Technology Data Exchange (ETDEWEB)

    Zimmermann, Elizabeth A.; Schaible, Eric; Bale, Hrishikesh; Barth, Holly D.; Tang, Simon Y.; Reichert, Peter; Busse, Bjoern; Alliston, Tamara; Ager III, Joel W.; Ritchie, Robert O.

    2011-08-10

    The structure of human cortical bone evolves over multiple length-scales from its basic constituents of collagen and hydroxyapatite at the nanoscale to osteonal structures at nearmillimeter dimensions, which all provide the basis for its mechanical properties. To resist fracture, bone’s toughness is derived intrinsically through plasticity (e.g., fibrillar sliding) at structural-scales typically below a micron and extrinsically (i.e., during crack growth) through mechanisms (e.g., crack deflection/bridging) generated at larger structural-scales. Biological factors such as aging lead to a markedly increased fracture risk, which is often associated with an age-related loss in bone mass (bone quantity). However, we find that age-related structural changes can significantly degrade the fracture resistance (bone quality) over multiple lengthscales. Using in situ small-/wide-angle x-ray scattering/diffraction to characterize sub-micron structural changes and synchrotron x-ray computed tomography and in situ fracture-toughness measurements in the scanning electron microscope to characterize effects at micron-scales, we show how these age-related structural changes at differing size-scales degrade both the intrinsic and extrinsic toughness of bone. Specifically, we attribute the loss in toughness to increased non-enzymatic collagen cross-linking which suppresses plasticity at nanoscale dimensions and to an increased osteonal density which limits the potency of crack-bridging mechanisms at micron-scales. The link between these processes is that the increased stiffness of the cross-linked collagen requires energy to be absorbed by “plastic” deformation at higher structural levels, which occurs by the process of microcracking.

  1. Influence of short-term fixation with mixed formalin or ethanol solution on the mechanical properties of human cortical bone

    Directory of Open Access Journals (Sweden)

    Mick E.

    2015-09-01

    Full Text Available Bone specimens obtained for biomechanical experiments are fresh-frozen for storage to slow down tissue degradation and autolysis in long-term storage. Alternatively, due to infectious risks related to the fresh tissues, fixative agents are commonly used. However, fixatives will likely change the mechanical properties of bone. Existing studies on this issue gave controversial results that are hardly comparable due to a variety of measurement approaches. For this reason, the influence of ethanol and a formalin-based fixative agent was evaluated on the mechanical properties of human cortical bone specimens by means of four-point-bending tests. 127 prismatic specimens with rectangular cross sections (2.5 x 2.5 x 20 mm3 were obtained from different regions of two fresh human femora (medial, lateral, dorsal, ventral. Specimens were either fixed in ethanol or in a mixed formalin solution or frozen following a given scheme. After two weeks of storage the samples were re-hydrated in isotonic saline and subsequently tested mechanically. The elastic bending modulus and ultimate bending strength were computed considering the actual dimensions of each specific specimen. For statistical analysis a one-way-ANOVA and an LSD post-hoc-test were performed. For ultimate bending strength no significant differences due to formalin or ethanol fixation, as compared to unfixed-fresh bone specimens could be found. And only for few cases significant differences in elastic bending modulus were observed when the two bones were evaluated separately. Since more differences of significant level due to the anatomical region of the samples were determined, the original location seems to have more influence on the evaluated mechanical properties than the method of (chemical fixation. Consequently, ethanol and the mixed formalin solution can be recommended as a fixation agent for samples in biomechanical testing, if these samples are rinsed in isotonic saline prior to static

  2. Intensive glycemic control and thiazolidinedione use: effects on cortical and trabecular bone at the radius and tibia.

    Science.gov (United States)

    Schwartz, Ann V; Vittinghoff, Eric; Margolis, Karen L; Scibora, Lesley M; Palermo, Lisa; Ambrosius, Walter T; Hue, Trisha F; Ensrud, Kristine E

    2013-05-01

    Factors that contribute to bone fragility in type 2 diabetes are not well understood. We assessed the effects of intensive glycemic control, thiazolidinediones (TZDs), and A1C levels on bone geometry and strength at the radius and tibia. In a substudy of the Action to Control Cardiovascular Risk in Diabetes trial, peripheral quantitative computed tomographic (pQCT) scans of the radius and tibia were obtained 2 years after randomization on 73 participants (intensive n = 35, standard n = 38). TZD use and A1C levels were measured every 4 months during the trial. Effects of intervention assignment, TZD use, and A1C on pQCT parameters were assessed in linear regression models. Intensive, compared with standard, glycemic control was associated with 1.3 % lower cortical volumetric BMD at the tibia in men (p = 0.02) but not with other pQCT parameters. In women, but not men, each additional year of TZD use was associated with an 11 % lower polar strength strain index (SSIp) at the radius (p = 0.04) and tibia (p = 0.002) in models adjusted for A1C levels. In women, each additional 1 % increase in A1C was associated with an 18 % lower SSIp at the ultradistal radius (p = 0.04) in models adjusted for TZD use. There was no consistent evidence of an effect of intensive, compared with standard, glycemic control on bone strength at the radius or tibia. In women, TZD use may reduce bone strength at these sites. Higher A1C may also be associated with lower bone strength at the radius, but not tibia, in women.

  3. Comparison of cortical bone measurements between pQCT and HR-pQCT.

    Science.gov (United States)

    Lala, Deena; Cheung, Angela M; Gordon, Chris; Giangregorio, Lora

    2012-01-01

    The primary purpose of this study was to determine the accuracy of tibial cortical thickness measurements derived from peripheral quantitative computed tomography (pQCT) with analysis based on the circular ring model, using high-resolution peripheral quantitative computed tomography (HR-pQCT) (isotopic voxel size of 82 μm) as a gold standard. The secondary objective was to evaluate whether the accuracy of the pQCT-based estimates of cortical thickness (CTh), cortical area (CoA), cortical density (CDen), and total area (TotA) improve with alterations of voxel size from the standard 0.5-0.2mm. Fifteen dry tibia specimens were immersed in saline in a sealed cylinder and scanned 22.5mm from the distal tibia plateau using pQCT and HR-pQCT. pQCT yielded higher values for CTh and CDen and lower values for CoA. The differences between imaging techniques increased as the average CTh increased. No systematic bias was observed for CDen, CoA, and TotA. Similar differences were found between pQCT with voxel size 0.2mm and HR-pQCT. Significant correlations were observed for CTh (R=0.97, p ≤ 0.0001), CDen (R=0.99, p ≤ 0.0001), CoA (R=0.98, p ≤ 0.0001), and TotA (R=1.0, p ≤ 0.0001) when pQCT- and HR-pQCT-derived values were compared irrespective of which voxel size was used. Measurement variability between the imaging techniques was evident. Future studies aimed at examining cortical structure with pQCT should note that there are differences between the 2 techniques. Copyright © 2012 The International Society for Clinical Densitometry. Published by Elsevier Inc. All rights reserved.

  4. Cortical and Trabecular Bone Microstructure Did Not Recover at Weight-Bearing Skeletal Sites and Progressively Deteriorated at Non-Weight-Bearing Sites During the Year Following International Space Station Missions.

    Science.gov (United States)

    Vico, Laurence; van Rietbergen, Bert; Vilayphiou, Nicolas; Linossier, Marie-Thérèse; Locrelle, Hervé; Normand, Myriam; Zouch, Mohamed; Gerbaix, Maude; Bonnet, Nicolas; Novikov, Valery; Thomas, Thierry; Vassilieva, Galina

    2017-06-02

    Risk for premature osteoporosis is a major health concern in astronauts and cosmonauts; the reversibility of the bone lost at the weight-bearing bone sites is not established, although it is suspected to take longer than the mission length. The bone three-dimensional structure and strength that could be uniquely affected by weightlessness is currently unknown. Our objective is to evaluate bone mass, microarchitecture, and strength of weight-bearing and non-weight-bearing bone in 13 cosmonauts before and for 12 months after a 4-month to 6-month sojourn in the International Space Station (ISS). Standard and advanced evaluations of trabecular and cortical parameters were performed using high-resolution peripheral quantitative computed tomography. In particular, cortical analyses involved determination of the largest common volume of each successive individual scan to improve the precision of cortical porosity and density measurements. Bone resorption and formation serum markers, and markers reflecting osteocyte activity or periosteal metabolism (sclerostin, periostin) were evaluated. At the tibia, in addition to decreased bone mineral densities at cortical and trabecular compartments, a 4% decrease in cortical thickness and a 15% increase in cortical porosity were observed at landing. Cortical size and density subsequently recovered and serum periostin changes were associated with cortical recovery during the year after landing. However, tibial cortical porosity or trabecular bone failed to recover, resulting in compromised strength. The radius, preserved at landing, unexpectedly developed postflight fragility, from 3 months post-landing onward, particularly in its cortical structure. Remodeling markers, uncoupled in favor of bone resorption at landing, returned to preflight values within 6 months, then declined farther to lower than preflight values. Our findings highlight the need for specific protective measures not only during, but also after spaceflight, because

  5. Irradiation conditions for fiber laser bonding of HAp-glass ceramics with bovine cortical bone.

    Science.gov (United States)

    Tadano, Shigeru; Yamada, Satoshi; Kanaoka, Masaru

    2014-01-01

    Orthopedic implants are widely used to repair bones and to replace articulating joint surfaces. It is important to develop an instantaneous technique for the direct bonding of bone and implant materials. The aim of this study was to develop a technique for the laser bonding of bone with an implant material like ceramics. Ceramic specimens (10 mm diameter and 1 mm thickness) were sintered with hydroxyapatite and MgO-Al2O3-SiO2 glass powders mixed in 40:60 wt% proportions. A small hole was bored at the center of a ceramic specimen. The ceramic specimen was positioned onto a bovine bone specimen and a 5 mm diameter area of the ceramic specimen was irradiated using a fiber laser beam (1070-1080 nm wavelength). As a result, the bone and the ceramic specimens bonded strongly under the irradiation conditions of a 400 W laser power and a 1.0 s exposure time. The maximum shear strength was 5.3 ± 2.3 N. A bonding substance that penetrated deeply into the bone specimen was generated around the hole in the ceramic specimen. On using the fiber laser, the ceramic specimen instantaneously bonded to the bone specimen. Further, the irradiation conditions required for the bonding were investigated.

  6. Three-Dimensional Analysis of the Contact Pattern between the Cortical Bone and Femoral Prosthesis after Cementless Total Hip Arthroplasty

    Directory of Open Access Journals (Sweden)

    Hiroshi Wada

    2016-01-01

    Full Text Available The cementless stem Excia (B. Braun, Melsungen, Germany implant has a rectangular cross-sectional shape with back-and-forth flanges and a plasma-sprayed, dicalcium phosphate dihydrate coating from the middle to proximal portion to increase initial fixation and early bone formation. Here, the conformity of the Excia stem to the femoral canal morphology was three-dimensionally assessed using computed tomography. Forty-three patients (45 hips were examined after primary total hip arthroplasty with a mean follow-up of 27 ± 3 months (range: 24–36 months. Spot welds occurred at zone 2 in 16 hips and at zone 6 in 24 hips, with 83% (20/24 hips of those occurring within 3 months after surgery. First- (n=12 hips, second- (n=32, and third- (n=1 degree stress shielding were observed. The stem was typically in contact with the cortical bone in the anterolateral mid-portion (100% and posteromedial distal portions (85%. Stress shielding did not progress, even in cases where the stems were in contact with the distal portions. The anterior flange was in contact with the bone in all cases. The stability of the mid-lateral portion with the dicalcium phosphate dihydrate coating and the anterior flange may have inhibited the progression of stress shielding beyond the second degree.

  7. 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

  8. 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

  9. Does the cortical bone resorption rate change due to 90Sr-radiation exposure? Analysis of data from Techa Riverside residents

    Energy Technology Data Exchange (ETDEWEB)

    Tolstykh, E I; Shagina, N B; Degteva, M O; Anspaugh, L R; Napier, Bruce A

    2011-08-01

    The Mayak Production Association released large amounts of 90Sr into the Techa River (Southern Urals, Russia) with peak amounts in 1950-1951. Techa Riverside residents ingested an average of about 3,000 kBq of 90Sr. The 90Sr-body burden of approximately 15,000 individuals has been measured in the Urals Research Center for Radiation Medicine in 1974-1997 with use of a special whole-body counter (WBC). Strontium-90 had mainly deposited in the cortical part of the skeleton by 25 years following intake, and 90Sr elimination occurs as a result of cortical bone resorption. The effect of 90Sr-radiation exposure on the rate of cortical bone resorption was studied. Data on 2,022 WBC measurements were selected for 207 adult persons, who were measured three or more times before they were 50-55 years old. The individual-resorption rates were calculated with the rate of strontium recirculation evaluated as 0.0018 year-1. Individual absorbed doses in red bone marrow (RBM) and bone surface (BS) were also calculated. Statistically significant negative relationships of cortical bone resorption rate were discovered related to 90Sr-body burden and dose absorbed in the RBM or the BS. The response appears to have a threshold of about 1.5-Gy RBM dose. The radiation induced decrease in bone resorption rate may not be significant in terms of health. However, a decrease in bone remodeling rate can be among several causes of an increased level of degenerative dystrophic bone pathology in exposed persons.

  10. Cortical EEG oscillations and network connectivity as efficacy indices for assessing drugs with cognition enhancing potential.

    Science.gov (United States)

    Ahnaou, A; Huysmans, H; Jacobs, T; Drinkenburg, W H I M

    2014-11-01

    Synchronization of electroencephalographic (EEG) oscillations represents a core mechanism for cortical and subcortical networks, and disturbance in neural synchrony underlies cognitive processing deficits in neurological and neuropsychiatric disorders. Here, we investigated the effects of cognition enhancers (donepezil, rivastigmine, tacrine, galantamine and memantine), which are approved for symptomatic treatment of dementia, on EEG oscillations and network connectivity in conscious rats chronically instrumented with epidural electrodes in different cortical areas. Next, EEG network indices of cognitive impairments with the muscarinic receptor antagonist scopolamine were modeled. Lastly, we examined the efficacy of cognition enhancers to normalize those aberrant oscillations. Cognition enhancers elicited systematic ("fingerprint") enhancement of cortical slow theta (4.5-6 Hz) and gamma (30.5-50 Hz) oscillations correlated with lower activity levels. Principal component analysis (PCA) revealed a compact cluster that corresponds to shared underlying mechanisms as compared to different drug classes. Functional network connectivity revealed consistent elevated coherent slow theta activity in parieto-occipital and between interhemispheric cortical areas. In rats instrumented with depth hippocampal CA1-CA3 electrodes, donepezil elicited similar oscillatory and coherent activities in cortico-hippocampal networks. When combined with scopolamine, the cognition enhancers attenuated the leftward shift in coherent slow delta activity. Such a consistent shift in EEG coherence into slow oscillations associated with altered slow theta and gamma oscillations may underlie cognitive deficits in scopolamine-treated animals, whereas enhanced coherent slow theta and gamma activity may be a relevant mechanism by which cognition enhancers exert their beneficial effect on plasticity and cognitive processes. The findings underscore that PCA and network connectivity are valuable tools to

  11. Segmentation of nanotomographic cortical bone images for quantitative characterization of the osteoctyte lacuno-canalicular network

    Energy Technology Data Exchange (ETDEWEB)

    Ciani, A.; Kewish, C. M. [Synchrotron Soleil, L’Orme des Merisiers, 91192 Saint-Aubin (France); Guizar-Sicairos, M.; Diaz, A.; Holler, M. [Paul Scherrer Institut, 5232 Villigen PSI (Switzerland); Pallu, S.; Achiou, Z.; Jennane, R.; Toumi, H.; Lespessailles, E. [Univ Orléans, I3MTO, Ea 4708, 45000 Orléans (France)

    2016-01-28

    A newly developed data processing method able to characterize the osteocytes lacuno-canalicular network (LCN) is presented. Osteocytes are the most abundant cells in the bone, living in spaces called lacunae embedded inside the bone matrix and connected to each other with an extensive network of canals that allows for the exchange of nutrients and for mechanotransduction functions. The geometrical three-dimensional (3D) architecture is increasingly thought to be related to the macroscopic strength or failure of the bone and it is becoming the focus for investigating widely spread diseases such as osteoporosis. To obtain 3D LCN images non-destructively has been out of reach until recently, since tens-of-nanometers scale resolution is required. Ptychographic tomography was validated for bone imaging in [1], showing clearly the LCN. The method presented here was applied to 3D ptychographic tomographic images in order to extract morphological and geometrical parameters of the lacuno-canalicular structures.

  12. Cortical bone growth and maturational changes in dwarf rats induced by recombinant human growth hormone

    Science.gov (United States)

    Martinez, D. A.; Orth, M. W.; Carr, K. E.; Vanderby, R. Jr; Vailas, A. C.

    1996-01-01

    The growth hormone (GH)-deficient dwarf rat was used to investigate recombinant human (rh) GH-induced bone formation and to determine whether rhGH facilitates simultaneous increases in bone formation and bone maturation during rapid growth. Twenty dwarf rats, 37 days of age, were randomly assigned to dwarf plus rhGH (GH; n = 10) and dwarf plus vehicle (n = 10) groups. The GH group received 1.25 mg rhGH/kg body wt two times daily for 14 days. Biochemical, morphological, and X-ray diffraction measurements were performed on the femur middiaphysis. rhGH stimulated new bone growth in the GH group, as demonstrated by significant increases (P growth.

  13. Optimization of process parameters for drilled hole quality characteristics during cortical bone drilling using Taguchi method.

    Science.gov (United States)

    Singh, Gurmeet; Jain, Vivek; Gupta, Dheeraj; Ghai, Aman

    2016-09-01

    Orthopaedic surgery involves drilling of bones to get them fixed at their original position. The drilling process used in orthopaedic surgery is most likely to the mechanical drilling process and there is all likelihood that it may harm the already damaged bone, the surrounding bone tissue and nerves, and the peril is not limited at that. It is very much feared that the recovery of that part may be impeded so that it may not be able to sustain life long. To achieve sustainable orthopaedic surgery, a surgeon must try to control the drilling damage at the time of bone drilling. The area around the holes decides the life of bone joint and so, the contiguous area of drilled hole must be intact and retain its properties even after drilling. This study mainly focuses on optimization of drilling parameters like rotational speed, feed rate and the type of tool at three levels each used by Taguchi optimization for surface roughness and material removal rate. The confirmation experiments were also carried out and results found with the confidence interval. Scanning electrode microscopy (SEM) images assisted in getting the micro level information of bone damage.

  14. Early cellular responses in cortical bone healing around unloaded titanium implants: an animal study.

    Science.gov (United States)

    Slaets, Elke; Carmeliet, Geert; Naert, Ignace; Duyck, Joke

    2006-06-01

    A clear understanding of the early cellular events leading to osseointegration of implants is currently lacking. To gain better insight, titanium implants were inserted in a rabbit model and histologic and histomorphometric analyses were performed at early time points after insertion. Thirty-six cylindrical implants were inserted in the tibial diaphysis of six rabbits and left to heal for 1 to 42 days. Samples were processed into paraffin or methylmethacrylate sections, on which the surface of new bone, region of altered nuclear morphology, relative surface of basic multicellular units (BMUs) and blood vessels, and bone-to-implant contact were measured. After coagulum formation, osteoclasts and osteoblasts were observed at the bone surface 1 week after healing. In the preexisting bone, osteocytic lacunae appeared to be devoid of cells. This region of altered nuclear morphology continued to extend for 28 days (P osteocytes surrounding the implantation site, intensive bone remodeling, and the formation of new bone, eventually leading to the osseointegration of the implant.

  15. Understanding site-specific residual strain and architecture in bovine cortical bone.

    Science.gov (United States)

    Giri, Bijay; Tadano, Shigeru; Fujisaki, Kazuhiro; Todoh, Masahiro

    2008-11-14

    Living bone is considered as adaptive material to the mechanical functions, which continually undergoes change in its histological arrangement with respect to external prolonged loading. Such remodeling phenomena within bone depend on the degree of stimuli caused by the mechanical loading being experienced, and therefore, are specific to the sites. In the attempts of understanding strain adaptive phenomena within bones, different theoretical models have been proposed. Also, the existing literatures mostly follow the measurement of surface strains using strain gauges to experimentally quantify the strains experienced in the functional environment. In this work, we propose a novel idea of understanding site-specific functional adaptation to the prolonged load in bone on the basis of inherited residual strains and structural organization. We quantified the residual strains and amount of apatite crystals distribution, i.e., the degree of orientation, using X-ray diffraction procedures. The sites of naturally existing hole in bone, called foramen, are considered from bovine femur and metacarpal samples. Significant values of residual strains are found to exist in the specimens. Trends of residual strains noted in the specimens are mostly consistent with the degree of orientation of the crystallites. These features explain the response behavior of bone to the mechanical loading history near the foramen sites. Preferential orientation of crystals mapped around a femoral foramen specimen showed furnished tailored arrangement of the crystals around the hole. Effect of external loading at the femoral foramen site is also explained by the tensile loading experiment.

  16. Effects of Habitual Physical Activity and Fitness on Tibial Cortical Bone Mass, Structure and Mass Distribution in Pre-pubertal Boys and Girls: The Look Study.

    Science.gov (United States)

    Duckham, Rachel L; Rantalainen, Timo; Ducher, Gaele; Hill, Briony; Telford, Richard D; Telford, Rohan M; Daly, Robin M

    2016-07-01

    Targeted weight-bearing activities during the pre-pubertal years can improve cortical bone mass, structure and distribution, but less is known about the influence of habitual physical activity (PA) and fitness. This study examined the effects of contrasting habitual PA and fitness levels on cortical bone density, geometry and mass distribution in pre-pubertal children. Boys (n = 241) and girls (n = 245) aged 7-9 years had a pQCT scan to measure tibial mid-shaft total, cortical and medullary area, cortical thickness, density, polar strength strain index (SSIpolar) and the mass/density distribution through the bone cortex (radial distribution divided into endo-, mid- and pericortical regions) and around the centre of mass (polar distribution). Four contrasting PA and fitness groups (inactive-unfit, inactive-fit, active-unfit, active-fit) were generated based on daily step counts (pedometer, 7-days) and fitness levels (20-m shuttle test and vertical jump) for boys and girls separately. Active-fit boys had 7.3-7.7 % greater cortical area and thickness compared to inactive-unfit boys (P < 0.05), which was largely due to a 6.4-7.8 % (P < 0.05) greater cortical mass in the posterior-lateral, medial and posterior-medial 66 % tibial regions. Cortical area was not significantly different across PA-fitness categories in girls, but active-fit girls had 6.1 % (P < 0.05) greater SSIpolar compared to inactive-fit girls, which was likely due to their 6.7 % (P < 0.05) greater total bone area. There was also a small region-specific cortical mass benefit in the posterior-medial 66 % tibia cortex in active-fit girls. Higher levels of habitual PA-fitness were associated with small regional-specific gains in 66 % tibial cortical bone mass in pre-pubertal children, particularly boys.

  17. A new implementation of digital X-ray radiogrammetry and reference curves of four indices of cortical bone for healthy European adults

    DEFF Research Database (Denmark)

    Thodberg, Hans Henrik; Böttcher, Joachim; Lomholt, Jens

    2016-01-01

    . PURPOSE: The digital X-ray radiogrammetry (DXR) method has been shown to be efficient for diagnosis of osteoporosis and for assessment of progression of rheumatoid arthritis. The aim of this work is to present a new DXR implementation and reference curves of four indices of cortical bone and to compare...

  18. Finite element analysis of dental implant loading on atrophic and non-atrophic cancellous and cortical mandibular bone - a feasibility study

    NARCIS (Netherlands)

    Marcián, P.; Borák, L.; Valášek, J.; Kaiser, J.; Florian, Z.; Wolff, J.

    2014-01-01

    The first aim of this study was to assess displacements and micro-strain induced on different grades of atrophic cortical and trabecular mandibular bone by axially loaded dental implants using finite element analysis (FEA). The second aim was to assess the micro-strain induced by different implant g

  19. Variations in the vestibular cortical bone of permanent canine teeth in orthodontic patients. a comparative study: linear tomography vs. cbct (3d accuitomo).

    Science.gov (United States)

    Mateu, María E; Martínez, M E; Dagum, H; Benítez Rogé, Sandra C; Bruno, Gabriela I; Hecht, Pedro; Folco, Alejandra A

    2014-01-01

    The aim of this study was to compare the results of measuring the height of the vestibular cortical bone of canine teeth by linear tomography (LT) and 3-D Accuitomo cone beam computed tomography (CBCT) before and after aligning dental arches by orthodontic treatment. LT and CBCT were performed before and after orthodontic alignment on 12 canines in three patients undergoing orthodontic treatment, and the height of the canine vestibular cortical bones measured in mm. Measurements were taken by double-blinded operators. The mean variation in height of the vestibular cortical bone with orthodontic treatment was - 0,33 mm} 0.233 standard error using CBCT and -0,08mm } 0.55 standard error using LT. Analysis of variance (ANOVA) was performed to compare the techniques, the patients and upper and lower canines. No significant difference was found for any of the cases. Using LT to evaluate vestibular crest cortical bone in canines is comparable in efficiency to using CBCT. Height in millimeters is less in LT because image resolution is lower and when it is very thin it is not appreciable by this method.

  20. Bone modeling and remodeling: potential as therapeutic targets for the treatment of osteoporosis.

    Science.gov (United States)

    Langdahl, Bente; Ferrari, Serge; Dempster, David W

    2016-12-01

    The adult skeleton is renewed by remodeling throughout life. Bone remodeling is a process where osteoclasts and osteoblasts work sequentially in the same bone remodeling unit. After the attainment of peak bone mass, bone remodeling is balanced and bone mass is stable for one or two decades until age-related bone loss begins. Age-related bone loss is caused by increases in resorptive activity and reduced bone formation. The relative importance of cortical remodeling increases with age as cancellous bone is lost and remodeling activity in both compartments increases. Bone modeling describes the process whereby bones are shaped or reshaped by the independent action of osteoblast and osteoclasts. The activities of osteoblasts and osteoclasts are not necessarily coupled anatomically or temporally. Bone modeling defines skeletal development and growth but continues throughout life. Modeling-based bone formation contributes to the periosteal expansion, just as remodeling-based resorption is responsible for the medullary expansion seen at the long bones with aging. Existing and upcoming treatments affect remodeling as well as modeling. Teriparatide stimulates bone formation, 70% of which is remodeling based and 20-30% is modeling based. The vast majority of modeling represents overflow from remodeling units rather than de novo modeling. Denosumab inhibits bone remodeling but is permissive for modeling at cortex. Odanacatib inhibits bone resorption by inhibiting cathepsin K activity, whereas modeling-based bone formation is stimulated at periosteal surfaces. Inhibition of sclerostin stimulates bone formation and histomorphometric analysis demonstrated that bone formation is predominantly modeling based. The bone-mass response to some osteoporosis treatments in humans certainly suggests that nonremodeling mechanisms contribute to this response and bone modeling may be such a mechanism. To date, this has only been demonstrated for teriparatide, however, it is clear that

  1. Investigation of the effect of movement and irrigation systems on temperature in the conventional drilling of cortical bone.

    Science.gov (United States)

    Gehrke, Sergio Alexandre; Loffredo Neto, Henrique; Mardegan, Fábio E C

    2013-12-01

    We have compared the results of the external irrigation technique with those of a double irrigation technique with continuous intermittent movement. Maximum thermal measurements were made in the cortical part of 10 samples of bovine ribs during osteotomy to simulate the preparation of a surgical bed for the installation of dental implants at a depth of 10 mm. Twenty specimens were drilled for each group: external irrigation and continuous movement (control group 1, CG1); external irrigation and intermittent movement (control group 2, CG2); double irrigation and continuous movement (test group 1, TG1); and double irrigation and intermittent movement (test group 2, TG2). The double irrigation technique gave significantly better results regardless of the drilling movement used. Thermal increases between samples was 19.2% in group CG1, 10.4% in CG2, 5.4% in TG1, and 3.4% in TG2. The double irrigation technique produced a significantly smaller increase in temperature in the cortical bone during both types of drilling (p=0.001), which illustrated its greater efficiency compared with that of the external irrigation technique.

  2. 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.

  3. Osteoinductive potential and bone-bonding ability of ProRoot MTA, MTA Plus and Biodentine in rabbit intramedullary model: Microchemical characterization and histological analysis.

    Science.gov (United States)

    Gandolfi, M G; Iezzi, G; Piattelli, A; Prati, C; Scarano, A

    2017-05-01

    To study the in vivo osteoinductive potential, bone-bonding ability (bioactivity) and bone biomineralization of current hydraulic calcium silicate cements used as graft materials and placed in contact with medullary bone. ProRoot MTA, MTA Plus and Biodentine were used to fill surgical bone defects (2-mm diameter through the entire cortical thickness to reach the medullary bone) in the tibia of mature male rabbits. Tibiae were retrieved after 30days and submitted to histological analysis and microchemical characterization using Optical Microscopy (OM) and Environmental Scanning Electron Microscopy with Energy Dispersive X-ray analysis (ESEM-EDX). Bone neoformation and histomorphometric evaluations, degree of mineralization (by Ca/P, Ca/N and P/N ratios) and the diffusion of material elements were studied. Bone neoformation was observed in response to all materials. No sign of necrosis were found on the walls of the pre-existing cortical bone. No osteoclasts and no formation of fibrous tissue were evident. Sign of angiogenesis were present. EDX (element content, line profile and element mapping) showed the increase in Ca and P and decrease in C, S and N from the mature bone towards the mineralizing interface. Ca/P, Ca/N and P/N ratios showed differences in the degree of mineralization/maturation stage of bone. MTA Plus and ProRoot MTA exhibited close contact with the pre-existing bone and good bone-bonding with neoformed bone juxtaposed on the medullary side of the materials without interposed connective tissue or resorption lacunae or gaps. The materials showed a dense appearance with 100% of residual materials and no colonization by fluids and cells. No migration of Bi or Al material elements to the newly formed bone was found. Biodentine showed newly formed trabecular bone with marrow spaces and sparse traces of residual material (≈9%). The in vivo osteoinductive properties with dynamic biomineralization processes around these calcium silicate materials extruded

  4. Mechanical tests on the reconstructed anterior cruciate ligament fixed with allogenetic cortical bone cross-pin on the femoral side

    Institute of Scientific and Technical Information of China (English)

    Liu Chang; Liu Yujie; Zhang Yingze; Qu Feng; Li Shuyuan; Wang Junliang; Qi Wei

    2014-01-01

    Background Anterior cruciate ligament reconstruction (ACLR) has developed dramatically in the last century.Now,ACLR has become a reliable and productive procedure.Patients feel satisfied in >90% cases.The aim of this study was to evaluate the feasibility of allogenetic cortical bone cross-pin (ACBCP) used as a clinical fixation method in anterior cruciate ligament reconstruction on the femoral side based on biomechanical tests in vitro.Methods The specimens were provided by the bone banks of the First Affiliated Hospital of People's Liberation Army of General Hospital from September 2011 to June 2012.Fresh deep frozen human allogenetic cortical bone was machined into cross-pins which is 4.0 mm in diameter and 75.0 mm in length.Biomechanical parameters compared with Rigidfix were collected while cross-pins were tested in double-shear test.The load-to-failure test and cycling test were carried out in a goat model to reconstruct anterior cruciate ligament with Achilles tendon autograft on the femoral side fixed by human 4.0 mm ACBCP and 3.3 mm Rigidfix served as control.Maximum failure load,yield load,and stiffness of fixation in single load-to-failure test were compared between the two groups.Cycle-specific stiffness and displacement at cycles 1,30,200,400,and 1 000 were also compared in between.Results In double-shear test both maximum failed load and yield load of 4.0 mm humanACBCP were (1 236.998±201.940) N.Maximum failed load and yield load of Rigidfix were (807.929±110.511) N and (592.483±58.821) N.The differences of maximum failed load and yield load were significant between ACBCP and Rigidfix,P <0.05.The shear strength of ACBCP and Rigidfix were (49.243±8.039) MPa and (34.637±3.439) MPa,respectively,P <0.05.In the load-to-failure test ex vivo,yield load and maximum failed load of ACBCP fixation complexity ((867.104±132.856)N,(1 032.243±196.281) N) were higher than those of Rigidfix ((640.935±42.836) N,(800.568±64.890) N,P <0.05).However

  5. Topographical Feature of Somatosensory Cortical Evoked Potential with Augmented Blocking of the Sensation Transmission along Meridians

    Institute of Scientific and Technical Information of China (English)

    许金森; 吴宝华; 胡翔龙; 杨广印; 韩丑萍

    2009-01-01

    Objective: To investigate the distribution features of somatosensory cortical evoked potential map with augmented blocking of the sensation transmission along meridians.Method: The EEG-4400 electro-encephalogram (EEG) and ND-1 brain electrical activity mapping were adopted on 11 volunteers with remarkable sensation transmission along meridians, showing that the sensation can transmit to head and face after stimulating the points below the knee joints. Also, special observation was made on accurate location of somatosensory cortical evoked potential map in 10 people without sensation transmission.Result: Observation on 11 volunteers with remarkable transmission along the Three Foot-yang Meridians showed that they presented with concurrent high potential reactions in somatosensory cortical lower limbs and face without blocking the augmented sensation transmission along the meridians; however, when mechanical pressure was exerted to block the sensation transmission,only one reaction in the lower limbs occurred in the somatosensory cortical evoked map and the other one in the face disappeared. Conclusion: Peripheral tissue evoking is the decisive factor for transmission along the meridians.%目的:探讨加压阻滞循经感传时皮层体觉诱发电位地形图的分布特点.方法:应用EEG 4400型脑电图仪和ND-1型脑地形图仪对11名循经感传显著的志愿者,刺激足三阳经膝关节以下穴位所引起的感传均可上行到头面部.另外,还对10名无感传者的皮层体觉诱发电位地形图的定位精确性进行了专门的观察.结果:对11名足三阳经循经感传显著的志愿者观察的结果表明,未加压阻滞循经感传时,在皮层体觉区的下肢和面部代表区同时出现了高电位反应.当以机械压迫阻滞感传,皮层体觉诱发电位地形图上只在下肢代表区出现一个反应,面部代表区的反应消失.结论:外周动因激发是产生循经感传现象的决定性因素.

  6. Direct motor evoked potentials and cortical mapping using the NIM® nerve monitoring system: A technical note.

    Science.gov (United States)

    Bharadwaj, Suparna; Haji, Faizal; Hebb, Matthew; Chui, Jason

    2017-04-01

    Motor evoked potentials (MEPs) are commonly used to prevent neurological injury when operating in close proximity to the motor cortex or corticospinal pathway. We report a novel application of the NIM® nerve monitoring system (Medtronic@ NIM response 3.0) for intraoperative direct cortical (dc)-MEPs monitoring. A 69-year-old female patient presented with a 4month history of progressive left hemiparesis resulting from a large right sided posterior frontal meningioma that abutted and compressed the motor cortex. Motor cortical mapping and MEPs were indicated. The patient was anesthetized and maintained on total intravenous anesthetics. Compound muscle action potentials (CMAP) of the right upper limb were monitored using the NIM system. After a craniotomy was performed, we first used the Ojemann stimulator (monopolar) for dc-stimulation and then switched to use the monopolar nerve stimulator probe of the NIM system. The CMAP response was successfully elicited using the NIM stimulating probe (pulse width=250s, train frequency=7pulses/s, current=20mA). A gross total resection of the tumor was achieved with intermittent cortical mapping of MEPs. There were no intraoperative complications and the patient's motor function was preserved after the surgery. In this case, we reported the successful use of the NIM nerve monitoring system to elicit dc-MEPs under general anesthesia. The advantages of using this system include a simple set up and application, neurosurgeon familiarity, wide availability and lower cost. dc-MEPs can be achieved using the NIM system. We conclude that the NIM nerve monitoring system is a feasible alternative to standard neurophysiological monitoring systems. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. A Review of Techniques for Detection of Movement Intention Using Movement-Related Cortical Potentials

    Directory of Open Access Journals (Sweden)

    Aqsa Shakeel

    2015-01-01

    Full Text Available The movement-related cortical potential (MRCP is a low-frequency negative shift in the electroencephalography (EEG recording that takes place about 2 seconds prior to voluntary movement production. MRCP replicates the cortical processes employed in planning and preparation of movement. In this study, we recapitulate the features such as signal’s acquisition, processing, and enhancement and different electrode montages used for EEG data recoding from different studies that used MRCPs to predict the upcoming real or imaginary movement. An authentic identification of human movement intention, accompanying the knowledge of the limb engaged in the performance and its direction of movement, has a potential implication in the control of external devices. This information could be helpful in development of a proficient patient-driven rehabilitation tool based on brain-computer interfaces (BCIs. Such a BCI paradigm with shorter response time appears more natural to the amputees and can also induce plasticity in brain. Along with different training schedules, this can lead to restoration of motor control in stroke patients.

  8. A Review of Techniques for Detection of Movement Intention Using Movement-Related Cortical Potentials.

    Science.gov (United States)

    Shakeel, Aqsa; Navid, Muhammad Samran; Anwar, Muhammad Nabeel; Mazhar, Suleman; Jochumsen, Mads; Niazi, Imran Khan

    2015-01-01

    The movement-related cortical potential (MRCP) is a low-frequency negative shift in the electroencephalography (EEG) recording that takes place about 2 seconds prior to voluntary movement production. MRCP replicates the cortical processes employed in planning and preparation of movement. In this study, we recapitulate the features such as signal's acquisition, processing, and enhancement and different electrode montages used for EEG data recoding from different studies that used MRCPs to predict the upcoming real or imaginary movement. An authentic identification of human movement intention, accompanying the knowledge of the limb engaged in the performance and its direction of movement, has a potential implication in the control of external devices. This information could be helpful in development of a proficient patient-driven rehabilitation tool based on brain-computer interfaces (BCIs). Such a BCI paradigm with shorter response time appears more natural to the amputees and can also induce plasticity in brain. Along with different training schedules, this can lead to restoration of motor control in stroke patients.

  9. Sensitivity of offset and onset cortical auditory evoked potentials to signals in noise.

    Science.gov (United States)

    Baltzell, Lucas S; Billings, Curtis J

    2014-02-01

    The purpose of this study was to determine the effects of SNR and signal level on the offset response of the cortical auditory evoked potential (CAEP). Successful listening often depends on how well the auditory system can extract target signals from competing background noise. Both signal onsets and offsets are encoded neurally and contribute to successful listening in noise. Neural onset responses to signals in noise demonstrate a strong sensitivity to signal-to-noise ratio (SNR) rather than signal level; however, the sensitivity of neural offset responses to these cues is not known. We analyzed the offset response from two previously published datasets for which only the onset response was reported. For both datasets, CAEPs were recorded from young normal-hearing adults in response to a 1000-Hz tone. For the first dataset, tones were presented at seven different signal levels without background noise, while the second dataset varied both signal level and SNR. Offset responses demonstrated sensitivity to absolute signal level in quiet, SNR, and to absolute signal level in noise. Offset sensitivity to signal level when presented in noise contrasts with previously published onset results. This sensitivity suggests a potential clinical measure of cortical encoding of signal level in noise.

  10. Preclinical investigation of an innovative magnesium-based bone graft substitute for potential orthopaedic applications

    Directory of Open Access Journals (Sweden)

    Chen Liu

    2014-07-01

    Full Text Available Degradable or corrosive biometal is an attractive research and development (R&D area in clinical orthopaedics. This study was designed to investigate biomechanical and biological properties of magnesium (Mg and strontium (Sr with a focus on Mg-based metals, including pure Mg and Mg–xwt% Sr (x = 0.25, x = 1.0, x = 1.5, x = 2.5 alloys, as potential bone graft substitutes in respect to their mechanical strength, corrosion resistance, and cytocompatibility for further optimization and establishing indications for relevant in vivo applications. Our data showed that the tensile and compressive strength increased with addition of Sr because of the Mg17Sr2 precipitation strengthen. Compared with commercially used bone graft substitutes, the mechanical properties of Mg–Sr alloys were close to those of cortical bone, and the compressive strength could reach 300 MPa, suggesting its potential application for load-bearing bone as bone defect filler. The corrosion rates of Mg–xwt% Sr alloys were controlled in the range of 0.05–0.07 mm/y, indicating feasibility of bone grafting and the in situ bone repair process. Moreover, Mg–Sr alloys also exhibit good cytocompatibility and antibacterial properties. Our innovation presented in this work supported in vivo clinical indication-based assessment of biodegradable Mg-based metals that could be potential candidates for bone graft substitutes for future orthopaedic applications.

  11. Cortical somatosensory evoked potentials from lumbosacral dermatomes: airpuff versus electrical stimulation.

    Science.gov (United States)

    Schimsheimer, R J; Boejharat, K R; van der Sluijs, J C; Stijnen, T; Gryz, E

    1995-01-01

    Cortical potentials were elicited by airpuff stimulation of the L5 and S1 dermatome in a group of 24 healthy volunteers. The results were compared with the SEPs obtained by conventional electrical stimulation. Both stimulus modalities produce stable and good reproducible cortical responses of similar waveform. The most stable second negative peak, labeled N2, was used in this study. Mean latencies (in msec) were: N2 L5 air = 67.1 +/- 3.3, N2 L5 electr. = 55.7 +/- 3.7 N2 S1 air = 67.2 +/- 3.9, and N2 S1 electr. = 55.1 +/- 2.9 The maximum R/L difference (mean + 3 SD) was 5.7 msec, 5.9 msec, 7.2 msec and 7.2 msec for respectively N2 L5 air, N2 L5 electrical, N2 S1 air and N2 S1 electrical. Single regression analysis showed a significant influence of height, but not age upon all latencies. Multiple regression analysis with height and age as independent variables showed a significant influence of height and age together upon the latencies of the electrical SEP (both L5 and S1). For the airpuff SEP only height was significant. Gender had no effect on the cortical components. The amplitude of peak N2 after electrical stimulation of the S1 dermatome was significant higher than after airpuff stimulation, 2.9 and 1.7 microvolt respectively. For the L5 dermatome both types of stimuli produced responses of nearly equal amplitude, 2.5 and 2.1 microvolt for electrical and airpuff stimulation respectively. Airpuff SEPs may provide a good alternative for electrical stimulation.

  12. Movement related slow cortical potentials in severely paralyzed chronic stroke patients

    Directory of Open Access Journals (Sweden)

    Ozge eYilmaz

    2015-01-01

    Full Text Available Movement-related slow cortical potentials (SCPs are proposed as reliable and immediate indicators of cortical reorganisation in motor learning. SCP amplitude and latency have been reported as markers for the brain’s computational effort, attention and movement planning. SCPs have been used as an EEG signature of motor control and as a main feature in Brain-Machine-Interfaces (BMIs. Some reports suggest SCPs are modified following stroke. In this study, we investigated movement-related SCPs in severe chronic stroke patients with no residual paretic hand movements preceding and during paretic (when they try to move and healthy hand movements. The aim was to identify SCP signatures related to cortex integrity and complete paralysis due to stroke in the chronic stage. 20 severely impaired (no residual finger extension chronic stoke patients, of whom 10 presented subcortical and 10 cortical and subcortical lesions, underwent EEG and EMG recordings during a cue triggered hand movement (open/close paradigm. SCP onset appeared and peaked significantly earlier during paretic hand movements than during healthy hand movements. Amplitudes were significantly larger over the midline (Cz, Fz for paretic hand movements while contralateral (C4, F4 and midline (Cz, Fz amplitudes were significantly larger than ipsilateral activity for healthy hand movements. Dividing the participants into subcortical only and mixed lesioned patient groups, no significant differences observed in SCP amplitude and latency between groups. This suggests lesions in the thalamocortical loop as the main factor in SCP changes after stroke. Furthermore, we demonstrated how, after long-term complete paralysis, post-stroke intention to move a paralyzed hand resulted in longer and larger SCPs originating in the frontal areas. These results suggest SCP are a valuable feature that should be incorporated in the design of new neurofeedback strategies for motor neurorehabilitation.

  13. Scanning transmission electron microscopic tomography of cortical bone using Z-contrast imaging.

    Science.gov (United States)

    McNally, Elizabeth; Nan, Feihong; Botton, Gianluigi A; Schwarcz, Henry P

    2013-06-01

    Previously we presented (McNally et al., 2012) a model for the ultrastructure of bone showing that the mineral resides principally outside collagen fibrils in the form of 5 nm thick mineral structures hundreds of nanometers long oriented parallel to the fibrils. Here we use high-angle annular dark-field electron tomography in the scanning transmission electron microscope to confirm this model and further elucidate the composite structure. Views of a section cut parallel to the fibril axes show bundles of mineral structures extending parallel to the fibrils and encircling them. The mineral density inside the fibrils is too low to be visualized in these tomographic images. A section cut perpendicular to the fibril axes, shows quasi-circular walls composed of mineral structures, wrapping around apparently empty holes marking the sites of fibrils. These images confirm our original model that the majority of mineral in bone resides outside the collagen fibrils.

  14. Small body size and extreme cortical bone remodeling indicate phyletic dwarfism in Magyarosaurus dacus (Sauropoda: Titanosauria).

    Science.gov (United States)

    Stein, Koen; Csiki, Zoltan; Rogers, Kristina Curry; Weishampel, David B; Redelstorff, Ragna; Carballido, Jose L; Sander, P Martin

    2010-05-18

    Sauropods were the largest terrestrial tetrapods (>10(5) kg) in Earth's history and grew at rates that rival those of extant mammals. Magyarosaurus dacus, a titanosaurian sauropod from the Upper Cretaceous (Maastrichtian) of Romania, is known exclusively from small individuals (dwarfism (phyletic nanism) in dinosaurs, but a recent study suggested that the small Romanian titanosaurs actually represent juveniles of a larger-bodied taxon. Here we present strong histological evidence that M. dacus was indeed a dwarf (phyletic nanoid). Bone histological analysis of an ontogenetic series of Magyarosaurus limb bones indicates that even the smallest Magyarosaurus specimens exhibit a bone microstructure identical to fully mature or old individuals of other sauropod taxa. Comparison of histologies with large-bodied sauropods suggests that Magyarosaurus had an extremely reduced growth rate, but had retained high basal metabolic rates typical for sauropods. The uniquely decreased growth rate and diminutive body size in Magyarosaurus were adaptations to life on a Cretaceous island and show that sauropod dinosaurs were not exempt from general ecological principles limiting body size.

  15. Influence of attention alternation on movement-related cortical potentials in healthy individuals and stroke patients.

    Science.gov (United States)

    Aliakbaryhosseinabadi, Susan; Kostic, Vladimir; Pavlovic, Aleksandra; Radovanovic, Sasa; Nlandu Kamavuako, Ernest; Jiang, Ning; Petrini, Laura; Dremstrup, Kim; Farina, Dario; Mrachacz-Kersting, Natalie

    2017-01-01

    In this study, we analyzed the influence of artificially imposed attention variations using the auditory oddball paradigm on the cortical activity associated to motor preparation/execution. EEG signals from Cz and its surrounding channels were recorded during three sets of ankle dorsiflexion movements. Each set was interspersed with either a complex or a simple auditory oddball task for healthy participants and a complex auditory oddball task for stroke patients. The amplitude of the movement-related cortical potentials (MRCPs) decreased with the complex oddball paradigm, while MRCP variability increased. Both oddball paradigms increased the detection latency significantly (pattention diversion. Attention diversion has a significant influence on MRCP features and detection parameters, although these changes were counteracted by the application of the laplacian method. Brain-computer interfaces for neuromodulation that use the MRCP as the control signal are robust to changes in attention. However, attention must be monitored since it plays a key role in plasticity induction. Here we demonstrate that this can be achieved using the single channel Cz. Copyright © 2016 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  16. Investigation of potential injectable polymeric biomaterials for bone regeneration.

    Science.gov (United States)

    Dreifke, Michael B; Ebraheim, Nabil A; Jayasuriya, Ambalangodage C

    2013-08-01

    This article reviews the potential injectable polymeric biomaterial scaffolds currently being investigated for application in bone tissue regeneration. Two types of injectable biomaterial scaffolds are focused in this review, including injectable microspheres and injectable gels. The injectable microspheres section covers several polymeric materials, including poly(L-lactide-co-glycolide)-PLGA, poly(propylene fumarate), and chitosan. The injectable gel section covers alginate gels, hyaluronan hydrogels, poly(ethylene-glycol)-PEG hydrogels, and PEG-PLGA copolymer hydrogels. This review focuses on the effect of cellular behavior in vitro and in vivo in terms of material properties of polymers, such as biodegradation, biocompatibility, porosity, microsphere size, and cross-linking nature. Injectable polymeric biomaterials offer a major advantage for orthopedic applications by allowing the ability to use noninvasive or minimally invasive treatment methods. Therefore, combining injectable polymeric biomaterial scaffolds with cells have a significant potential to treat orthopedic bone defects, including spine fusion, and craniofacial and periodontal defects.

  17. The cortical spatiotemporal correlate of otolith stimulation: vestibular evoked potentials by body translations.

    Science.gov (United States)

    Ertl, M; Moser, M; Boegle, R; Conrad, J; Zu Eulenburg, P; Dieterich, M

    2017-02-22

    The vestibular organ senses linear and rotational acceleration of the head during active and passive motion. These signals are necessary for bipedal locomotion, navigation, the coordination of eye and head movements in 3D space. The temporal dynamics of vestibular processing in cortical structures have hardly been studied in humans, let alone with natural stimulation. The aim was to investigate the cortical vestibular network related to natural otolith stimulation using a hexapod motion platform. We conducted two experiments, 1. to estimate the sources of the vestibular evoked potentials (VestEPs) by means of distributed source localization (n=49), and 2. to reveal modulations of the VestEPs through the underlying acceleration intensity (n=24). For both experiments subjects were accelerated along the main axis (left/right, up/down, fore/aft) while the EEG was recorded. We were able to identify five VestEPs (P1, N1, P2, N2, P3) with latencies between 38 and 461 ms as well as an evoked beta-band response peaking with a latency of 68 ms in all subjects and for all acceleration directions. Source localization gave the cingulate sulcus visual (CSv) area and the opercular-insular region as the main origin of the evoked potentials. No lateralization effects due to handedness could be observed. In the second experiment, area CSv was shown to be integral in the processing of acceleration intensities as sensed by the otolith organs, hinting at its potential role in ego-motion detection. These robust VestEPs could be used to investigate the mechanisms of inter-regional interaction in the natural context of vestibular processing and multisensory integration.

  18. Noninvasive scalp recording of cortical auditory evoked potentials in the alert macaque monkey.

    Science.gov (United States)

    Itoh, Kosuke; Nejime, Masafumi; Konoike, Naho; Nakada, Tsutomu; Nakamura, Katsuki

    2015-09-01

    Scalp-recorded evoked potentials (EP) provide researchers and clinicians with irreplaceable means for recording stimulus-related neural activities in the human brain, due to its high temporal resolution, handiness, and, perhaps more importantly, non-invasiveness. This work recorded the scalp cortical auditory EP (CAEP) in unanesthetized monkeys by using methods that are essentially identical to those applied to humans. Young adult rhesus monkeys (Macaca mulatta, 5-7 years old) were seated in a monkey chair, and their head movements were partially restricted by polystyrene blocks and tension poles placed around their head. Individual electrodes were fixated on their scalp using collodion according to the 10-20 system. Pure tone stimuli were presented while electroencephalograms were recorded from up to nineteen channels, including an electrooculogram channel. In all monkeys (n = 3), the recorded CAEP comprised a series of positive and negative deflections, labeled here as macaque P1 (mP1), macaque N1 (mN1), macaque P2 (mP2), and macaque N2 (mN2), and these transient responses to sound onset were followed by a sustained potential that continued for the duration of the sound, labeled the macaque sustained potential (mSP). mP1, mN2 and mSP were the prominent responses, and they had maximal amplitudes over frontal/central midline electrode sites, consistent with generators in auditory cortices. The study represents the first noninvasive scalp recording of CAEP in alert rhesus monkeys, to our knowledge. Copyright © 2015 Elsevier B.V. All rights reserved.

  19. A novel underuse model shows that inactivity but not ovariectomy determines the deteriorated material properties and geometry of cortical bone in the tibia of adult rats.

    Science.gov (United States)

    Miyagawa, Kazuaki; Kozai, Yusuke; Ito, Yumi; Furuhama, Takami; Naruse, Kouji; Nonaka, Kiichi; Nagai, Yumiko; Yamato, Hideyuki; Kashima, Isamu; Ohya, Keiichi; Aoki, Kazuhiro; Mikuni-Takagaki, Yuko

    2011-07-01

    Our goal in this study was to determine to what extent the physiologic consequences of ovariectomy (OVX) in bones are exacerbated by a lack of daily activity such as walking. We forced 14-week-old female rats to be inactive for 15 weeks with a unique experimental system that prevents standing and walking while allowing other movements. Tibiae, femora, and 4th lumbar vertebrae were analyzed by peripheral quantitative computed tomography (pQCT), microfocused X-ray computed tomography (micro-CT), histology, histomorphometry, Raman spectroscopy, and the three-point bending test. Contrary to our expectation, the exacerbation was very much limited to the cancellous bone parameters. Parameters of femur and tibia cortical bone were affected by the forced inactivity but not by OVX: (1) cross-sectional moment of inertia was significantly smaller in Sham-Inactive rat bones than that of their walking counterparts; (2) the number of sclerostin-positive osteocytes per unit cross-sectional area was larger in Sham-Inactive rat bones than in Sham-Walking rat bones; and (3) material properties such as ultimate stress of inactive rat tibia was lower than that of their walking counterparts. Of note, the additive effect of inactivity and OVX was seen only in a few parameters, such as the cancellous bone mineral density of the lumbar vertebrae and the structural parameters of cancellous bone in the lumbar vertebrae/tibiae. It is concluded that the lack of daily activity is detrimental to the strength and quality of cortical bone in the femur and tibia of rats, while lack of estrogen is not. Our inactive rat model, with the older rats, will aid the study of postmenopausal osteoporosis, the etiology of which may be both hormonal and mechanical.

  20. Cortical evoked potentials in response to rapid balloon distension of the rectum and anal canal

    DEFF Research Database (Denmark)

    Haas, S; Brock, C; Krogh, K;

    2014-01-01

    BACKGROUND: Neurophysiological evaluation of anorectal sensory function is hampered by a paucity of methods. Rapid balloon distension (RBD) has been introduced to describe the cerebral response to rectal distension, but it has not successfully been applied to the anal canal. METHODS: Nineteen...... healthy women received 30 RBDs in the rectum and the anal canal at intensities corresponding to sensory and unpleasantness thresholds, and response was recorded as cortical evoked potentials (CEPs) in 64-channels. The anal canal stimulations at unpleasantness level were repeated after 4 min to test...... the within-day reproducibility. CEPs were averaged, and to overcome latency variation related to jitter the spectral content of single sweeps was also computed. KEY RESULTS: Repeated stimulation of the anal canal generated CEPs with similar latencies but smaller amplitudes compared to those from the rectum...

  1. Preparation of laponite bioceramics for potential bone tissue engineering applications.

    Directory of Open Access Journals (Sweden)

    Chuanshun Wang

    Full Text Available We report a facile approach to preparing laponite (LAP bioceramics via sintering LAP powder compacts for bone tissue engineering applications. The sintering behavior and mechanical properties of LAP compacts under different temperatures, heating rates, and soaking times were investigated. We show that LAP bioceramic with a smooth and porous surface can be formed at 800°C with a heating rate of 5°C/h for 6 h under air. The formed LAP bioceramic was systematically characterized via different methods. Our results reveal that the LAP bioceramic possesses an excellent surface hydrophilicity and serum absorption capacity, and good cytocompatibility and hemocompatibility as demonstrated by resazurin reduction assay of rat mesenchymal stem cells (rMSCs and hemolytic assay of pig red blood cells, respectively. The potential bone tissue engineering applicability of LAP bioceramic was explored by studying the surface mineralization behavior via soaking in simulated body fluid (SBF, as well as the surface cellular response of rMSCs. Our results suggest that LAP bioceramic is able to induce hydroxyapatite deposition on its surface when soaked in SBF and rMSCs can proliferate well on the LAP bioceramic surface. Most strikingly, alkaline phosphatase activity together with alizarin red staining results reveal that the produced LAP bioceramic is able to induce osteoblast differentiation of rMSCs in growth medium without any inducing factors. Finally, in vivo animal implantation, acute systemic toxicity test and hematoxylin and eosin (H&E-staining data demonstrate that the prepared LAP bioceramic displays an excellent biosafety and is able to heal the bone defect. Findings from this study suggest that the developed LAP bioceramic holds a great promise for treating bone defects in bone tissue engineering.

  2. Preparation of laponite bioceramics for potential bone tissue engineering applications.

    Science.gov (United States)

    Wang, Chuanshun; Wang, Shige; Li, Kai; Ju, Yaping; Li, Jipeng; Zhang, Yongxing; Li, Jinhua; Liu, Xuanyong; Shi, Xiangyang; Zhao, Qinghua

    2014-01-01

    We report a facile approach to preparing laponite (LAP) bioceramics via sintering LAP powder compacts for bone tissue engineering applications. The sintering behavior and mechanical properties of LAP compacts under different temperatures, heating rates, and soaking times were investigated. We show that LAP bioceramic with a smooth and porous surface can be formed at 800°C with a heating rate of 5°C/h for 6 h under air. The formed LAP bioceramic was systematically characterized via different methods. Our results reveal that the LAP bioceramic possesses an excellent surface hydrophilicity and serum absorption capacity, and good cytocompatibility and hemocompatibility as demonstrated by resazurin reduction assay of rat mesenchymal stem cells (rMSCs) and hemolytic assay of pig red blood cells, respectively. The potential bone tissue engineering applicability of LAP bioceramic was explored by studying the surface mineralization behavior via soaking in simulated body fluid (SBF), as well as the surface cellular response of rMSCs. Our results suggest that LAP bioceramic is able to induce hydroxyapatite deposition on its surface when soaked in SBF and rMSCs can proliferate well on the LAP bioceramic surface. Most strikingly, alkaline phosphatase activity together with alizarin red staining results reveal that the produced LAP bioceramic is able to induce osteoblast differentiation of rMSCs in growth medium without any inducing factors. Finally, in vivo animal implantation, acute systemic toxicity test and hematoxylin and eosin (H&E)-staining data demonstrate that the prepared LAP bioceramic displays an excellent biosafety and is able to heal the bone defect. Findings from this study suggest that the developed LAP bioceramic holds a great promise for treating bone defects in bone tissue engineering.

  3. Serum MicroRNA-4521 is a Potential Biomarker for Focal Cortical Dysplasia with Refractory Epilepsy.

    Science.gov (United States)

    Wang, Xiaofeng; Sun, Yuqiang; Tan, Zeshi; Che, Ningwei; Ji, Anlong; Luo, Xiaodong; Sun, Xu; Li, Xinyu; Yang, Kang; Wang, Guanyu; Luan, Lan; Liu, Yaoling; Wei, Minghai; Yin, Jian

    2016-04-01

    Early biomarker-based diagnosis of focal cortical dysplasia (FCD) represents a major clinical challenge. The aim of this study was to identify novel brain microRNAs (miRNAs) in patients with refractory epilepsy and FCD as potential biomarkers. We evaluated serum hsa-miR-4521 as a promising novel biomarker in patients with FCD. Tissue for microarray was obtained from nine patients with temporal lobe refractory epilepsy who underwent surgery to remove epileptic foci identified by cortical video electroencephalogram monitoring. Control tissue was collected from eight patients with hypertension who required emergency surgery to remove an intracranial hematoma. The Affymetrix® GeneChip® Command Console® Software (Affymetrix miRNA 4.0) was used to compare miRNA expression in the cerebral cortex of experimental and control patients. Temporal cortex tissue and serum samples were taken from the same patients for verification of hsa-miR-4521 expression by real-time quantitative polymerase chain reaction (RT-qPCR). The experimental and control patients did not differ significantly in terms of age and gender. 19.4 % (148/764) of the total miRNAs were differentially expressed in experimental and control tissue, which is in agreement with the existing literature. We selected miRNA-4521 for further analysis; the fold-change in expression was 14.4707 and the q value was almost 0, which confirmed up-regulation. Significant up-regulation of hsa-miR-4521 was further validated by RT-qPCR. miRNA microarrays can efficiently and conveniently identify differentially expressed miRNAs in epilepsy brain tissue. This is the first study to identify differential expression of hsa-miR-4521 in brain tissue and serum of refractory epilepsy patients and suggests that serum hsa-miR-4521 may represent a potential diagnostic biomarker for FCD with refractory epilepsy.

  4. Digital image processing of bone - Problems and potentials

    Science.gov (United States)

    Morey, E. R.; Wronski, T. J.

    1980-01-01

    The development of a digital image processing system for bone histomorphometry and fluorescent marker monitoring is discussed. The system in question is capable of making measurements of UV or light microscope features on a video screen with either video or computer-generated images, and comprises a microscope, low-light-level video camera, video digitizer and display terminal, color monitor, and PDP 11/34 computer. Capabilities demonstrated in the analysis of an undecalcified rat tibia include the measurement of perimeter and total bone area, and the generation of microscope images, false color images, digitized images and contoured images for further analysis. Software development will be based on an existing software library, specifically the mini-VICAR system developed at JPL. It is noted that the potentials of the system in terms of speed and reliability far exceed any problems associated with hardware and software development.

  5. Regulation of action potential waveforms by axonal GABAA receptors in cortical pyramidal neurons.

    Directory of Open Access Journals (Sweden)

    Yang Xia

    Full Text Available GABAA receptors distributed in somatodendritic compartments play critical roles in regulating neuronal activities, including spike timing and firing pattern; however, the properties and functions of GABAA receptors at the axon are still poorly understood. By recording from the cut end (bleb of the main axon trunk of layer -5 pyramidal neurons in prefrontal cortical slices, we found that currents evoked by GABA iontophoresis could be blocked by picrotoxin, indicating the expression of GABAA receptors in axons. Stationary noise analysis revealed that single-channel properties of axonal GABAA receptors were similar to those of somatic receptors. Perforated patch recording with gramicidin revealed that the reversal potential of the GABA response was more negative than the resting membrane potential at the axon trunk, suggesting that GABA may hyperpolarize the axonal membrane potential. Further experiments demonstrated that the activation of axonal GABAA receptors regulated the amplitude and duration of action potentials (APs and decreased the AP-induced Ca2+ transients at the axon. Together, our results indicate that the waveform of axonal APs and the downstream Ca2+ signals are modulated by axonal GABAA receptors.

  6. Classification of Hand Grasp Kinetics and Types Using Movement-Related Cortical Potentials and EEG Rhythms

    Directory of Open Access Journals (Sweden)

    Mads Jochumsen

    2017-01-01

    Full Text Available Detection of single-trial movement intentions from EEG is paramount for brain-computer interfacing in neurorehabilitation. These movement intentions contain task-related information and if this is decoded, the neurorehabilitation could potentially be optimized. The aim of this study was to classify single-trial movement intentions associated with two levels of force and speed and three different grasp types using EEG rhythms and components of the movement-related cortical potential (MRCP as features. The feature importance was used to estimate encoding of discriminative information. Two data sets were used. 29 healthy subjects executed and imagined different hand movements, while EEG was recorded over the contralateral sensorimotor cortex. The following features were extracted: delta, theta, mu/alpha, beta, and gamma rhythms, readiness potential, negative slope, and motor potential of the MRCP. Sequential forward selection was performed, and classification was performed using linear discriminant analysis and support vector machines. Limited classification accuracies were obtained from the EEG rhythms and MRCP-components: 0.48±0.05 (grasp types, 0.41±0.07 (kinetic profiles, motor execution, and 0.39±0.08 (kinetic profiles, motor imagination. Delta activity contributed the most but all features provided discriminative information. These findings suggest that information from the entire EEG spectrum is needed to discriminate between task-related parameters from single-trial movement intentions.

  7. EFFECTS OF CHEMICAL PROCESSING AND OXIDE ETHYLENE STERILIZATION ON CORTICAL AND CANCELLOUS RAT BONE: A LIGHT AND ELECTRON SCANNING MICROSCOPY STUDY.

    Science.gov (United States)

    Castiglia, Marcello Teixeira; da Silva, Juliano Voltarelli F; Frezarim Thomazini, José Armendir; Volpon, José Batista

    2009-01-01

    To evaluate, under microscopic examination, the structural changes displayed by the trabecular and cortical bones after being processed chemically and sterilized by ethylene oxide. Samples of cancellous and cortical bones obtained from young female albinus rats (Wistar) were assigned to four groups according to the type of treatment: Group I- drying; Group II- drying and ethylene oxide sterilization; III- chemical treatment; IV- chemical treatment and ethylene oxide sterilization. Half of this material was analyzed under ordinary light microscope and the other half using scanning electron microscopy. In all the samples, regardless the group, there was good preservation of the general morphology. For samples submitted to the chemical processing there was better preservation of the cellular content, whereas there was amalgamation of the fibres when ethylene oxide was used. Treatment with ethylene oxide caused amalgamation of the fibers, possibly because of heating and the chemical treatment contributed to a better cellular preservation of the osseous structure.

  8. 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...

  9. Comparison of interradicular distances and cortical bone thickness in Thai patients with class I and class II skeletal patterns using cone-beam computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Khumsarn, Nattida [Dental Division of Lamphun Hospital, Lamphun (Thailand); Patanaporn, Virush; Janhom, Apirum; Jotikasthira, Dhirawat [Faculty of Dentistry, Chiang Mai University, Chiang Mai (Thailand)

    2016-06-15

    This study evaluated and compared interradicular distances and cortical bone thickness in Thai patients with Class I and Class II skeletal patterns, using cone-beam computed tomography (CBCT). Pretreatment CBCT images of 24 Thai orthodontic patients with Class I and Class II skeletal patterns were included in the study. Three measurements were chosen for investigation: the mesiodistal distance between the roots, the width of the buccolingual alveolar process, and buccal cortical bone thickness. All distances were recorded at five different levels from the cementoenamel junction (CEJ). Descriptive statistical analysis and t-tests were performed, with the significance level for all tests set at p<0.05. Patients with a Class II skeletal pattern showed significantly greater maxillary mesiodistal distances (between the first and second premolars) and widths of the buccolingual alveolar process (between the first and second molars) than Class I skeletal pattern patients at 10 mm above the CEJ. The maxillary buccal cortical bone thicknesses between the second premolar and first molar at 8 mm above the CEJ in Class II patients were likewise significantly greater than in Class I patients. Patients with a Class I skeletal pattern showed significantly wider mandibular buccolingual alveolar processes than did Class II patients (between the first and second molars) at 4, 6, and 8 mm below the CEJ. In both the maxilla and mandible, the mesiodistal distances, the width of the buccolingual alveolar process, and buccal cortical bone thickness tended to increase from the CEJ to the apex in both Class I and Class II skeletal patterns.

  10. Comparison of interradicular distances and cortical bone thickness in Thai patients with Class I and Class II skeletal patterns using cone-beam computed tomography

    Science.gov (United States)

    Khumsarn, Nattida; Patanaporn, Virush; Jotikasthira, Dhirawat

    2016-01-01

    Purpose This study evaluated and compared interradicular distances and cortical bone thickness in Thai patients with Class I and Class II skeletal patterns, using cone-beam computed tomography (CBCT). Materials and Methods Pretreatment CBCT images of 24 Thai orthodontic patients with Class I and Class II skeletal patterns were included in the study. Three measurements were chosen for investigation: the mesiodistal distance between the roots, the width of the buccolingual alveolar process, and buccal cortical bone thickness. All distances were recorded at five different levels from the cementoenamel junction (CEJ). Descriptive statistical analysis and t-tests were performed, with the significance level for all tests set at p<0.05. Results Patients with a Class II skeletal pattern showed significantly greater maxillary mesiodistal distances (between the first and second premolars) and widths of the buccolingual alveolar process (between the first and second molars) than Class I skeletal pattern patients at 10 mm above the CEJ. The maxillary buccal cortical bone thicknesses between the second premolar and first molar at 8 mm above the CEJ in Class II patients were likewise significantly greater than in Class I patients. Patients with a Class I skeletal pattern showed significantly wider mandibular buccolingual alveolar processes than did Class II patients (between the first and second molars) at 4, 6, and 8 mm below the CEJ. Conclusion In both the maxilla and mandible, the mesiodistal distances, the width of the buccolingual alveolar process, and buccal cortical bone thickness tended to increase from the CEJ to the apex in both Class I and Class II skeletal patterns. PMID:27358819

  11. The use of a 3-dimensional computed tomography bone database to evaluate the risk of distal contact between the rasp tip and the endosteal cortical bone.

    Science.gov (United States)

    Connor, Emmalynn; Cowie, Jonathan G; Wuestemann, Thies; Howell, Jonathan R; Whitehouse, Sarah L; Crawford, Ross W

    2016-12-01

    To use a 3-dimensional computed tomography (CT) bone database to evaluate the risk of distal contact between the rasp tip and the endosteal cortical bone. Using a 3-dimensional CT bone database, the rasps for Exeter stems of 125 mm in length and body size 1, with a femoral offset of 37.5, 44, or 50 mm were compared with those for Exeter stems of 150 mm in length and same body size with the corresponding femoral offset. Rasp geometry was determined using an engineering drawing software. Of the 631 femurs in the database, 238 (187 Caucasian and 51 Asian) were of appropriate femoral offset and proximal body size to receive a stem with an offset of 37.5, 44, or 50 mm. Of these, 145 (115 Caucasian and 30 Asian) femurs were of champagne-flute type; the prevalence was comparable between the 2 populations (61% vs. 59%, p=0.729). When using the 150-mm rasp, 70 (55 Caucasian and 15 Asian) of the 238 femurs had distal contact between the rasp and femoral cortex; the prevalence was comparable between the 2 populations (29% vs. 29%, relative risk=1.0, p=1.0). Distal contact between the rasp and femoral cortex occurred more commonly in champagne-flute-type femurs than other femurs in the anteroposterior plane (28% [41/145] vs. 2% [2/93], relative risk=13.1, p<0.001) and in the mediolateral plane (27% [39/145] vs. 14% [13/93], relative risk=1.92, p=0.019). When using the 125-mm rasp, only one femur (with a canal flare index of 4.52) had distal contact in the mediolateral plane with an offset of 37.5 mm. Distal contact between the rasp and femoral cortex occurred more often with the 150-mm rasp than the 125-mm rasp in both planes (p<0.001). The use of a shorter stem may enhance anatomic fit in patients with a narrow femoral canal and prevent distal contact between the rasp and femoral cortex.

  12. Subthalamic and Cortical Local Field Potentials Associated with Pilocarpine-Induced Oral Tremor in the Rat.

    Science.gov (United States)

    Long, Lauren L; Podurgiel, Samantha J; Haque, Aileen F; Errante, Emily L; Chrobak, James J; Salamone, John D

    2016-01-01

    Tremulous jaw movements (TJMs) are rapid vertical deflections of the lower jaw that resemble chewing but are not directed at any particular stimulus. In rodents, TJMs are induced by neurochemical conditions that parallel those seen in human Parkinsonism, including neurotoxic or pharmacological depletion of striatal dopamine (DA), DA antagonism, and cholinomimetic administration. Moreover, TJMs in rodents can be attenuated by antiparkinsonian agents, including levodopa (L-DOPA), DA agonists, muscarinic antagonists, and adenosine A2A antagonists. In human Parkinsonian patients, exaggerated physiological synchrony is seen in the beta frequency band in various parts of the cortical/basal ganglia/thalamic circuitry, and activity in the tremor frequency range (3-7 Hz) also has been recorded. The present studies were undertaken to determine if tremor-related local field potential (LFP) activity could be recorded from motor cortex (M1) or subthalamic nucleus (STN) during the TJMs induced by the muscarinic agonist pilocarpine, which is a well-known tremorogenic agent. Pilocarpine induced a robust TJM response that was marked by rhythmic electromyographic (EMG) activity in the temporalis muscle. Compared to periods with no tremor activity, TJM epochs were characterized by increased LFP activity in the tremor frequency range in both neocortex and STN. Tremor activity was not associated with increased synchrony in the beta frequency band. These studies identified tremor-related LFP activity in parts of the cortical/basal ganglia circuitry that are involved in the pathophysiology of Parkinsonism. This research may ultimately lead to identification of the oscillatory neural mechanisms involved in the generation of tremulous activity, and promote development of novel treatments for tremor disorders.

  13. TMS-induced cortical potentiation during wakefulness locally increases slow wave activity during sleep.

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    Reto Huber

    Full Text Available BACKGROUND: Sleep slow wave activity (SWA is thought to reflect sleep need, increasing in proportion to the length of prior wakefulness and decreasing during sleep. However, the process responsible for SWA regulation is not known. We showed recently that SWA increases locally after a learning task involving a circumscribed brain region, suggesting that SWA may reflect plastic changes triggered by learning. METHODOLOGY/PRINCIPAL FINDINGS: To test this hypothesis directly, we used transcranial magnetic stimulation (TMS in conjunction with high-density EEG in humans. We show that 5-Hz TMS applied to motor cortex induces a localized potentiation of TMS-evoked cortical EEG responses. We then show that, in the sleep episode following 5-Hz TMS, SWA increases markedly (+39.1+/-17.4%, p<0.01, n = 10. Electrode coregistration with magnetic resonance images localized the increase in SWA to the same premotor site as the maximum TMS-induced potentiation during wakefulness. Moreover, the magnitude of potentiation during wakefulness predicts the local increase in SWA during sleep. CONCLUSIONS/SIGNIFICANCE: These results provide direct evidence for a link between plastic changes and the local regulation of sleep need.

  14. Controlled evaluation of a neurofeedback training of slow cortical potentials in children with Attention Deficit/Hyperactivity Disorder (ADHD

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    Heinrich Hartmut

    2007-07-01

    Full Text Available Abstract Background Although several promising studies on neurofeedback training in Attention Deficit/Hyperactivity Disorder (ADHD have been performed in recent years, the specificity of positive treatment effects continues to be challenged. Methods To evaluate the specificity of a neurofeedback training of slow cortical potentials, a twofold strategy was pursued: First, the efficacy of neurofeedback training was compared to a group training program for children with ADHD. Secondly, the extent of improvements observed in the neurofeedback group in relation to successful regulation of cortical activation was examined. Parents and teachers rated children's behaviour and executive functions before and after treatment. In addition, children underwent neuropsychological testing before and after training. Results According to parents' and teachers' ratings, children of the neurofeedback training group improved more than children who had participated in a group therapy program, particularly in attention and cognition related domains. On neuropsychological measures children of both groups showed similar improvements. However, only about half of the neurofeedback group learned to regulate cortical activation during a transfer condition without direct feedback. Behavioural improvements of this subgroup were moderately related to neurofeedback training performance, whereas effective parental support accounted better for some advantages of neurofeedback training compared to group therapy according to parents' and teachers' ratings. Conclusion There is a specific training effect of neurofeedback of slow cortical potentials due to enhanced cortical control. However, non-specific factors, such as parental support, may also contribute to the positive behavioural effects induced by the neurofeedback training.

  15. Differences in Cortical Sources of the Event-Related P3 Potential Between Young and Old Participants Indicate Frontal Compensation.

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    van Dinteren, R; Huster, R J; Jongsma, M L A; Kessels, R P C; Arns, M

    2017-01-18

    The event-related P3 potential, as elicited in auditory signal detection tasks, originates from neural activity of multiple cortical structures and presumably reflects an overlap of several cognitive processes. The fact that the P3 is affected by aging makes it a potential metric for age-related cognitive change. The P3 in older participants is thought to encompass frontal compensatory activity in addition to task-related processes. The current study investigates this by decomposing the P3 using group independent component analysis (ICA). Independent components (IC) of young and old participants were compared in order to investigate the effects of aging. Exact low-resolution tomography analysis (eLORETA) was used to compare current source densities between young and old participants for the P3-ICs to localize differences in cortical source activity for every IC. One of the P3-related ICs reflected a different constellation of cortical generators in older participants compared to younger participants, suggesting that this P3-IC reflects shifts in neural activations and compensatory processes with aging. This P3-IC was localized to the orbitofrontal/temporal, and the medio-parietal regions. For this IC, older participants showed more frontal activation and less parietal activation as measured on the scalp. The differences in cortical sources were localized in the precentral gyrus and the parahippocampal gyrus. This finding might reflect compensatory activity recruited from these cortical sources during a signal detection task.

  16. Space Nutrition: Effects on Bone and Potential Nutrition Countermeasures

    Science.gov (United States)

    Smith, Scott M.

    2008-01-01

    Optimal nutrition will be critical for crew members who embark on space exploration missions. Nutritional assessment provides an opportunity to ensure that crewmembers begin their missions in optimal nutritional status, to document changes during a mission and , if necessary, to provide intervention to maintain that status throughout the mission, and to assesses changes after landing in order to facilitate the return to their normal status as soon as possible after landing. We report here the findings from our nutritional assessment of the US astronauts who participated in the first eight International Space Station (ISS) missions. Bone loss during space flight remains one of the most critical challenges to astronaut health on space exploration missions. An increase in bone resorption of ISS crew members after flight was indicated by several markers. Vitamin D status also remains a challenge for long-duration space travelers, who lack ultraviolet light exposure in the shielded craft. Many nutrients affect bone, including calcium, protein, fatty acids, sodium, and others. Data supporting their potential as countermeasures for space flight, as published in many papers, will be reviewed in this presentation. Defining nutrient requirements, and being able to provide and maintain those nutrients on exploration missions, will be critical for maintaining crew member health. Please note, this abstract is not required for the meeting. A presentation on the topics described above will be given. This abstract is for travel documentation only.

  17. Fetal and neonatal exposure to the endocrine disruptor, methoxychlor, reduces lean body mass and bone mineral density and increases cortical porosity.

    Science.gov (United States)

    Fagnant, Heather S; Uzumcu, Mehmet; Buckendahl, Patricia; Dunn, Michael G; Shupper, Peter; Shapses, Sue A

    2014-12-01

    Endogenous estrogen has beneficial effects on mature bone and negatively affects the developing skeleton, whereas the effect of environmental estrogens is not known. Methoxychlor (MXC) is a synthetic estrogen known as a persistent organochlorine and used as a pesticide. Methoxychlor and its metabolites display estrogenic, anti-estrogenic and anti-androgenic activity and may therefore influence bone. Fifty-eight male fetal and neonatal rats were exposed to either: a negative control (DMSO), 0.020, 100 mg/kg MXC, or 1 mg/kg β-estradiol-3-benzoate (EB; positive control). Rats were treated daily for 11 days, from embryonic day 19 to postnatal day (PND) 7 or for 4 days during the postnatal period (PND 0-7). All rats were analyzed at PND-84. Total body, femur, spine, and tibia areal bone mineral density (BMD) and content (BMC), lean body mass (LBM) and fat were measured by dual energy X-ray absorptiometry. Bone geometry and volumetric (v) BMD were measured using micro-computed tomography and biomechanical properties using three-point bending were assessed. Rats exposed to EB or MXC (at either the high and/or low dose), independent of exposure interval showed lower body weight, LBM, tibia and femur BMD and length, and total body BMD and BMC than DMSO control group (p ≤ 0.05). Methoxychlor and EB exposure increased cortical porosity compared to DMSO controls. Trabecular vBMD, number and separation, and cortical polar moment of inertia and cross-sectional area were lower due to EB exposure compared to control (p < 0.05). Early MXC exposure compromises cortical porosity and bone size at maturity, and could ultimately increase the risk of fracture with aging.

  18. Interleukin-10 Inhibits Bone Resorption: A Potential Therapeutic Strategy in Periodontitis and Other Bone Loss Diseases

    Science.gov (United States)

    Guo, Jianbin; Zhu, Xiaofeng; Ma, Shouzhi; Yang, Wenrong

    2014-01-01

    Periodontitis and other bone loss diseases, decreasing bone volume and strength, have a significant impact on millions of people with the risk of tooth loss and bone fracture. The integrity and strength of bone are maintained through the balance between bone resorption and bone formation by osteoclasts and osteoblasts, respectively, so the loss of bone results from the disruption of such balance due to increased resorption or/and decreased formation of bone. The goal of therapies for diseases of bone loss is to reduce bone loss, improve bone formation, and then keep healthy bone density. Current therapies have mostly relied on long-term medication, exercise, anti-inflammatory therapies, and changing of the life style. However there are some limitations for some patients in the effective treatments for bone loss diseases because of the complexity of bone loss. Interleukin-10 (IL-10) is a potent anti-inflammatory cytokine, and recent studies have indicated that IL-10 can contribute to the maintenance of bone mass through inhibition of osteoclastic bone resorption and regulation of osteoblastic bone formation. This paper will provide a brief overview of the role of IL-10 in bone loss diseases and discuss the possibility of IL-10 adoption in therapy of bone loss diseases therapy. PMID:24696846

  19. Cross-approximate entropy of cortical local field potentials quantifies effects of anesthesia - a pilot study in rats

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    Schwarz Cornelius

    2010-09-01

    Full Text Available Abstract Background Anesthetics dose-dependently shift electroencephalographic (EEG activity towards high-amplitude, slow rhythms, indicative of a synchronization of neuronal activity in thalamocortical networks. Additionally, they uncouple brain areas in higher (gamma frequency ranges possibly underlying conscious perception. It is currently thought that both effects may impair brain function by impeding proper information exchange between cortical areas. But what happens at the local network level? Local networks with strong excitatory interconnections may be more resilient towards global changes in brain rhythms, but depend heavily on locally projecting, inhibitory interneurons. As anesthetics bias cortical networks towards inhibition, we hypothesized that they may cause excessive synchrony and compromise information processing already on a small spatial scale. Using a recently introduced measure of signal independence, cross-approximate entropy (XApEn, we investigated to what degree anesthetics synchronized local cortical network activity. We recorded local field potentials (LFP from the somatosensory cortex of three rats chronically implanted with multielectrode arrays and compared activity patterns under control (awake state with those at increasing concentrations of isoflurane, enflurane and halothane. Results Cortical LFP signals were more synchronous, as expressed by XApEn, in the presence of anesthetics. Specifically, XApEn was a monotonously declining function of anesthetic concentration. Isoflurane and enflurane were indistinguishable; at a concentration of 1 MAC (the minimum alveolar concentration required to suppress movement in response to noxious stimuli in 50% of subjects both volatile agents reduced XApEn by about 70%, whereas halothane was less potent (50% reduction. Conclusions The results suggest that anesthetics strongly diminish the independence of operation of local cortical neuronal populations, and that the

  20. Movement-related cortical potentials in paraplegic patients: abnormal patterns and considerations for BCI-rehabilitation

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    Ren eXu

    2014-08-01

    Full Text Available Non-invasive EEG-based Brain-Computer Interfaces (BCI can be promising for the motor neuro-rehabilitation of paraplegic patients. However, this shall require detailed knowledge of the abnormalities in the EEG signatures of paraplegic patients. The association of abnormalities in different subgroups of patients and their relation to the sensorimotor integration are relevant for the design, implementation and use of BCI systems in patient populations. This study explores the patterns of abnormalities of movement related cortical potentials (MRCP during motor imagery tasks of feet and right hand in patients with paraplegia (including the subgroups with/without central neuropathic pain and complete/incomplete injury patients and the level of distinctiveness of abnormalities in these groups using pattern classification. The most notable observed abnormalities were the amplified execution negativity and its slower rebound in the patient group. The potential underlying mechanisms behind these changes and other minor dissimilarities in patients’ subgroups, as well as the relevance to BCI applications, are discussed. The findings are of interest from a neurological perspective as well as for BCI-assisted neuro-rehabilitation and therapy.

  1. Visual Evoked Potentials as a Readout of Cortical Function in Infants With Tuberous Sclerosis Complex.

    Science.gov (United States)

    Varcin, Kandice J; Nelson, Charles A; Ko, Jordan; Sahin, Mustafa; Wu, Joyce Y; Jeste, Shafali Spurling

    2016-02-01

    Tuberous sclerosis complex is an autosomal dominant genetic disorder that confers a high risk for neurodevelopmental disorders, such as autism spectrum disorder and intellectual disability. Studies have demonstrated specific delays in visual reception skills that may predict the development of autism spectrum disorder and intellectual disability. Based on evidence for alterations in the retinogeniculate pathway in animal models of tuberous sclerosis complex, we asked whether children with tuberous sclerosis complex demonstrate alterations in early visual processing that may undermine the development of higher-level visual behaviors. Pattern-reversal visual evoked potentials were recorded in infants with tuberous sclerosis complex (n = 16) and typically developing infants (n = 18) at 12 months of age. Infants with tuberous sclerosis complex demonstrated remarkably intact visual evoked potentials even within the context of intellectual disability and epilepsy. Infants with tuberous sclerosis complex show intact visual cortical processing, suggesting that delays in visually mediated behaviors in tuberous sclerosis complex may not be rooted in early visual processing deficits.

  2. THE APPLICATION OF CORTICAL SOMATOSENSORY EVOKED POTENTIAL MONITORING IN CHILD SCOLIOSIS SURGERY

    Institute of Scientific and Technical Information of China (English)

    白斌; 王坤正; 同志勤; 刘文科; 宋金辉; 袁国莲

    2003-01-01

    Objective To study the application value of cortical somatosensory evoked potential (CSEP) monitoring in child scoliosis surgery. Methods In surgeries of fifty-one children with scoliosis, the CSEP changes were continuously recorded by evoked potential instrument. The operations were performed under the guidance of CSEP monitoring. Results Before propping and reshaping, the latencies and amplitudes in all cases had no change. During propping and reshaping, the latencies of all cases were slowly elongated, but all less than 10 percent. The amplitudes in 15 cases dropped to 55 percent, but returned to 80 percent 3-8 minutes after stopping the operations or partially loosening the propped rods at once. The amplitude in one case suddenly dropped to 37 percent and returned to 54 percent half an hour after loosening the propped rods at once and recovered to the normal range one day after operation. All cases got ideal orthopedic results and no one had neurological complications post operation. Conclusion CSEP can accurately monitor the spinal injury and has a great value in preventing the spinal injury in child scoliosis surgery.

  3. Quantifying the Effects of Formalin Fixation on the Mechanical Properties of Cortical Bone Using Beam Theory and Optimization Methodology With Specimen-Specific Finite Element Models.

    Science.gov (United States)

    Zhang, Guan-Jun; Yang, Jie; Guan, Feng-Jiao; Chen, Dan; Li, Na; Cao, Libo; Mao, Haojie

    2016-09-01

    The effects of formalin fixation on bone material properties remain debatable. In this study, we collected 36 fresh-frozen cuboid-shaped cortical specimens from five male bovine femurs and immersed half of the specimens into 4% formalin fixation liquid for 30 days. We then conducted three-point bending tests and used both beam theory method and an optimization method combined with specimen-specific finite element (FE) models to identify material parameters. Through the optimization FE method, the formalin-fixed bones showed a significantly lower Young's modulus (-12%) compared to the fresh-frozen specimens, while no difference was observed using the beam theory method. Meanwhile, both the optimization FE and beam theory methods revealed higher effective failure strains for formalin-fixed bones compared to fresh-frozen ones (52% higher through the optimization FE method and 84% higher through the beam theory method). Hence, we conclude that the formalin fixation has a significant effect on bovine cortical bones at small, elastic, as well as large, plastic deformations.

  4. MRI of the temporo-mandibular joint: which sequence is best suited to assess the cortical bone of the mandibular condyle? A cadaveric study using micro-CT as the standard of reference

    Energy Technology Data Exchange (ETDEWEB)

    Karlo, Christoph A. [University Hospital Zurich, Department of Diagnostic and Interventional Radiology, Zurich (Switzerland); University Children' s Hospital Zurich, Department of Diagnostic Imaging, Zurich (Switzerland); Patcas, Raphael; Signorelli, Luca; Mueller, Lukas [University of Zurich, Clinic for Orthodontics and Pediatric Dentistry, Center of Dental Medicine, Zurich (Switzerland); Kau, Thomas; Watzal, Helmut; Kellenberger, Christian J. [University Children' s Hospital Zurich, Department of Diagnostic Imaging, Zurich (Switzerland); Ullrich, Oliver [University of Zurich, Institute of Anatomy, Faculty of Medicine, Zurich (Switzerland); Luder, Hans-Ulrich [University of Zurich, Section of Orofacial Structures and Development, Center of Dental Medicine, Zurich (Switzerland)

    2012-07-15

    To determine the best suited sagittal MRI sequence out of a standard temporo-mandibular joint (TMJ) imaging protocol for the assessment of the cortical bone of the mandibular condyles of cadaveric specimens using micro-CT as the standard of reference. Sixteen TMJs in 8 human cadaveric heads (mean age, 81 years) were examined by MRI. Upon all sagittal sequences, two observers measured the cortical bone thickness (CBT) of the anterior, superior and posterior portions of the mandibular condyles (i.e. objective analysis), and assessed for the presence of cortical bone thinning, erosions or surface irregularities as well as subcortical bone cysts and anterior osteophytes (i.e. subjective analysis). Micro-CT of the condyles was performed to serve as the standard of reference for statistical analysis. Inter-observer agreements for objective (r = 0.83-0.99, P < 0.01) and subjective ({kappa} = 0.67-0.88) analyses were very good. Mean CBT measurements were most accurate, and cortical bone thinning, erosions, surface irregularities and subcortical bone cysts were best depicted on the 3D fast spoiled gradient echo recalled sequence (3D FSPGR). The most reliable MRI sequence to assess the cortical bone of the mandibular condyles on sagittal imaging planes is the 3D FSPGR sequence. (orig.)

  5. The temporal relationship between the brainstem and primary cortical auditory evoked potentials.

    Science.gov (United States)

    Shaw, N A

    1995-10-01

    Many methods are employed in order to define more precisely the generators of an evoked potential (EP) waveform. One technique is to compare the timing of an EP whose origin is well established with that of one whose origin is less certain. In the present article, the latency of the primary cortical auditory evoked potential (PCAEP) was compared to each of the seven subcomponents which compose the brainstem auditory evoked potential (BAEP). The data for this comparison was derived from a retrospective analysis of previous recordings of the PCAEP and BAEP. Central auditory conduction time (CACT) was calculated by subtracting the latency of the cochlear nucleus BAEP component (wave III) from that of the PCAEP. It was found that CACT in humans is 12 msec which is more than double that of central somatosensory conduction time. The interpeak latencies between BAEP waves V, VI, and VII and the PCAEP were also calculated. It was deduced that all three waves must have an origin rather more caudally within the central auditory system than is commonly supposed. In addition, it is demonstrated that the early components of the middle latency AEP (No and Na) largely reside within the time domain between the termination of the BAEP components and the PCAEP which would be consistent with their being far field reflections of midbrain and subcortical auditory activity. It is concluded that as the afferent volley ascends the central auditory pathways, it generates not a sequence of high frequency BAEP responses but rather a succession of slower post-synaptic waves. The only means of reconciling the timing of the BAEP waves with that of the PCAEP is to assume that the generation of all the BAEP components must be largely restricted to a quite confined region within the auditory nerve and the lower half of the pons.

  6. USO DO ENXERTO ÓSSEO CORTICAL BOVINO CONSERVADO EM GLICERINA A 98% NA OSTEOTOMIA FEMORAL EM GATOS USE BOVINE CORTICAL BONE, PRESERVED IN 98% GLICERIN IN FEMORAL OSTEOTOMY IN CATS.

    Directory of Open Access Journals (Sweden)

    Lucia Helena de Carvalho Penha

    2008-12-01

    . The objective of this study was to evaluate clinically and radiographically the efficacy of xenografts as a substitute for methalic implants. Animals were divided into two groups: five young cats and five adult cats. Clinically, the weight-bearing on the operated limb was observed the day after surgery in all animals, with complete remission of lameness at 15 days and bone union in 16.6 weeks. In five young animals, in two of them, the grafts were fractured carrying a serious bone bending without fracture of feline femur. In the last two young cats, remodeling was noted in mean time of 75 days or 10.7 weeks. In five adult cats, all of them suffered overriding of the fragments of osteotomized bone with various degrees, where two cases were considered severe cases dut to fracture of feline femur without bone bending. In the three remaining animals with slightly overriding, one was a case of delayed union, one suffered tow surgical procedures due to graft fracture and one did not show a radiographic exuberant bone callus, with remodeling at 110 days. The use of the bonive xenograft preserved in 98% glycerol in young and adult cats used as intramedularry nails was perfectly employed, offering mechanical support in time of bone consolidation in all of 10 animals.

    KEY WORDS: Cortical bovine graft, cats, femur, fracture, osteotomy.

  7. Direct cortical stimulation but not transcranial electrical stimulation motor evoked potentials detect brain ischemia during brain tumor resection.

    Science.gov (United States)

    Li, Fenghua; Deshaies, Eric M; Allott, Geoffrey; Canute, Gregory; Gorji, Reza

    2011-09-01

    Motor evoked potentials (MEPs) elicited by both direct cortical stimulation (DCS) and transcranial electrical stimulation are used during brain tumor resection. Parallel use of direct cortical stimulation motor evoked potentials (DCS-MEPs) and transcranial electrical stimulation motor evoked potentials (TCeMEPs) has been practiced during brain tumor resection. We report that DCS-MEPs elicited by direct subdural grid stimulation, but not TCeMEPs, detected brain ischemia during brain tumor resection. Following resection of a brainstem high-grade glioma in a 21-year-old, the threshold of cortical motor-evoked-potentials (cMEPs) increased from 13 mA to 20 mA while amplitudes decreased. No changes were noted in transcranial motor evoked potentials (TCMEPs), somatosensory evoked potentials (SSEPs), auditory evoked potentials (AEPs), anesthetics, or hemodynamic parameters. Our case showed the loss of cMEPs and SSEPs, but not TCeMEPs. Permanent loss of DCS-MEPs and SSEPs was correlated with permanent left hemiplegia in our patient even when appropriate action was taken. Parallel use of DCS- and TCeMEPs with SSEPs improves sensitivity of intraoperative detection of motor impairment. DCS may be superior to TCeMEPs during brain tumor resection.

  8. 皮质骨块加松质骨治疗牙槽嵴裂的临床研究%Clinical study on the treatment of alveolar cleft with cortical bone block affiliate with cancellous bone

    Institute of Scientific and Technical Information of China (English)

    陈恒丕; 王涛

    2013-01-01

    目的:牙槽嵴裂常与唇腭裂伴发,表现为牙槽嵴的骨质缺损。目前,自体髂骨移植治疗牙槽嵴裂是目前的最广泛治疗方式。但髂骨松质骨移植吸收率高,移植的最终治疗效果并不能完全满足临床要求。本研究采用皮质骨块加松质骨移植治疗牙槽嵴裂,了解是否能提高治疗效果。材料和方法:牙槽嵴裂患者21例,采用髂骨植骨,包括髂骨皮质骨块加骨松质移植和单纯松质骨移植两种方式。术后6个月,采用锥形束CT复查获取影像学资料,对比两种治疗方式的影像学资料中的牙槽骨的剩余量,确定治疗效果。结果:通过髂骨皮质骨块加松质骨移植后的牙槽骨的剩余量大于单纯松质骨移植的牙槽骨的剩余量。结论:对于治疗牙槽嵴裂,皮质骨块加松质骨移植作为一种治疗方法能够提高治疗效果。%Objective :Autologous bone grafts are widely used to treat alveolar cleft associated with cleft lip and palate , showing alveolar bone defects . However ,due to the high absorption rate of iliac cancellous bone grafts ,the clinical requirements are not fully satisfied .In this study ,cortical bone block affiliate with cancellous bone were used to treat alveolar cleft to determine whether there could be any improvement on therapeutic results .Materials and Methods :21 patients with alveolar cleft were treated with cortical bone block affiliate with cancellous bone grafts and cancellous bone grafts from iliac .Six months after the surgical procedures ,Cone-beam CT scanning were executed and the volume of bone of each type of the two treatment methods was calculated to find out the therapeutic results .Results :The volume of alveolar bone formed from cortical bone block affiliate with cancellous bone grafts is greater than cancellous bone grafts alone .Conclusions :For treatment of alveolar cleft ,cortical bone block affiliate with cancellous bone grafts is one method

  9. Chromatic spatial contrast sensitivity estimated by visual evoked cortical potential and psychophysics.

    Science.gov (United States)

    Barboni, M T S; Gomes, B D; Souza, G S; Rodrigues, A R; Ventura, D F; Silveira, L C L

    2013-02-01

    The purpose of the present study was to measure contrast sensitivity to equiluminant gratings using steady-state visual evoked cortical potential (ssVECP) and psychophysics. Six healthy volunteers were evaluated with ssVECPs and psychophysics. The visual stimuli were red-green or blue-yellow horizontal sinusoidal gratings, 5° × 5°, 34.3 cd/m2 mean luminance, presented at 6 Hz. Eight spatial frequencies from 0.2 to 8 cpd were used, each presented at 8 contrast levels. Contrast threshold was obtained by extrapolating second harmonic amplitude values to zero. Psychophysical contrast thresholds were measured using stimuli at 6 Hz and static presentation. Contrast sensitivity was calculated as the inverse function of the pooled cone contrast threshold. ssVECP and both psychophysical contrast sensitivity functions (CSFs) were low-pass functions for red-green gratings. For electrophysiology, the highest contrast sensitivity values were found at 0.4 cpd (1.95 ± 0.15). ssVECP CSF was similar to dynamic psychophysical CSF, while static CSF had higher values ranging from 0.4 to 6 cpd (P psychophysical methods (P psychophysical thresholds, mainly if the same temporal properties are applied to the stimulus. For blue-yellow CSF, correlation between electrophysiology and psychophysics was poor at high spatial frequency, possibly due to a greater effect of chromatic aberration on this kind of stimulus.

  10. Discriminative Manifold Learning Based Detection of Movement-Related Cortical Potentials.

    Science.gov (United States)

    Lin, Chuang; Wang, Bing-Hui; Jiang, Ning; Xu, Ren; Mrachacz-Kersting, Natalie; Farina, Dario

    2016-09-01

    The detection of voluntary motor intention from EEG has been applied to closed-loop brain-computer interfacing (BCI). The movement-related cortical potential (MRCP) is a low frequency component of the EEG signal, which represents movement intention, preparation, and execution. In this study, we aim at detecting MRCPs from single-trial EEG traces. For this purpose, we propose a detector based on a discriminant manifold learning method, called locality sensitive discriminant analysis (LSDA), and we test it in both online and offline experiments with executed and imagined movements. The online and offline experimental results demonstrated that the proposed LSDA approach for MRCP detection outperformed the Locality Preserving Projection (LPP) approach, which was previously shown to be the most accurate algorithm so far tested for MRCP detection. For example, in the online tests, the performance of LSDA was superior than LPP in terms of a significant reduction in false positives (FP) (passive FP: 1.6 ±0.9/min versus 2.9 ±1.0/min, p = 0.002, active FP: 2.2 ±0.8/min versus 2.7 ±0.6/min , p = 0.03 ), for a similar rate of true positives. In conclusion, the proposed LSDA based MRCP detection method is superior to previous approaches and is promising for developing patient-driven BCI systems for motor function rehabilitation as well as for neuroscience research.

  11. Slow Cortical Potentials and Amplification—Part I: N1-P2 Measures

    Directory of Open Access Journals (Sweden)

    Susan Marynewich

    2012-01-01

    Full Text Available Slow cortical potentials (SCPs are currently of great interest in the hearing aid fitting process for infants; however, there is conflicting evidence in the literature concerning the use of SCPs for this purpose. The current study investigated SCP amplitudes and latencies in young normal-hearing listeners in response to a 60 ms duration tonal stimulus (1000 Hz presented at three intensities (30, 50, and 70 dB SPL in aided and unaided conditions using three hearing aids (Analog, DigitalA, and DigitalB with two gain settings (20 and 40 dB. Results showed that SCP amplitudes were smaller for the digital hearing aids compared with the analog hearing aid, and none of the hearing aids resulted in a reliable increase in response amplitude relative to the unaided across conditions. SCP latencies in analog conditions were not significantly different from latencies in the unaided conditions; however, both digital hearing aids resulted in significantly delayed SCP latencies. The results of the current study (as well as several previous studies indicate that the SCP may not accurately reflect the amplified stimulus expected from the prescribed hearing aids. Thus, “aided-SCP” results must be interpreted with caution, and more research is required concerning possible clinical use of this technique.

  12. Cortical inhibition of laser pain and laser-evoked potentials by non-nociceptive somatosensory input.

    Science.gov (United States)

    Testani, Elisa; Le Pera, Domenica; Del Percio, Claudio; Miliucci, Roberto; Brancucci, Alfredo; Pazzaglia, Costanza; De Armas, Liala; Babiloni, Claudio; Rossini, Paolo Maria; Valeriani, Massimiliano

    2015-10-01

    Although the inhibitory action that tactile stimuli can have on pain is well documented, the precise timing of the interaction between the painful and non-painful stimuli in the central nervous system is unclear. The aim of this study was to investigate this issue by measuring the timing of the amplitude modulation of laser evoked potentials (LEPs) due to conditioning non-painful stimuli. LEPs were recorded from 31 scalp electrodes in 10 healthy subjects after painful stimulation of the right arm (C6-C7 dermatomes). Non-painful electrical stimuli were applied by ring electrodes on the second and third finger of the right hand. Electrical stimuli were delivered at +50, +150, +200 and +250 ms interstimulus intervals (ISIs) after the laser pulses. LEPs obtained without any conditioning stimulation were used as a baseline. As compared to the baseline, non-painful electrical stimulation reduced the amplitude of the vertex N2/P2 LEP component and the laser pain rating when electrical stimuli followed the laser pulses only at +150 and +200 ms ISIs. As at these ISIs the collision between the non-painful and painful input is likely to take place at the cortical level, we can conclude that the late processing of painful (thermal) stimuli is partially inhibited by the processing of non-painful (cutaneous) stimuli within the cerebral cortex. Moreover, our results do not provide evidence that non-painful inputs can inhibit pain at a lower level, including the spinal cord.

  13. Dendritic Properties Control Energy Efficiency of Action Potentials in Cortical Pyramidal Cells

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    Guosheng Yi

    2017-09-01

    Full Text Available Neural computation is performed by transforming input signals into sequences of action potentials (APs, which is metabolically expensive and limited by the energy available to the brain. The metabolic efficiency of single AP has important consequences for the computational power of the cell, which is determined by its biophysical properties and morphologies. Here we adopt biophysically-based two-compartment models to investigate how dendrites affect energy efficiency of APs in cortical pyramidal neurons. We measure the Na+ entry during the spike and examine how it is efficiently used for generating AP depolarization. We show that increasing the proportion of dendritic area or coupling conductance between two chambers decreases Na+ entry efficiency of somatic AP. Activating inward Ca2+ current in dendrites results in dendritic spike, which increases AP efficiency. Activating Ca2+-activated outward K+ current in dendrites, however, decreases Na+ entry efficiency. We demonstrate that the active and passive dendrites take effects by altering the overlap between Na+ influx and internal current flowing from soma to dendrite. We explain a fundamental link between dendritic properties and AP efficiency, which is essential to interpret how neural computation consumes metabolic energy and how biophysics and morphologies contribute to such consumption.

  14. Detection of movement intention from single-trial movement-related cortical potentials

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    Niazi, Imran Khan; Jiang, Ning; Tiberghien, Olivier; Feldbæk Nielsen, Jørgen; Dremstrup, Kim; Farina, Dario

    2011-10-01

    Detection of movement intention from neural signals combined with assistive technologies may be used for effective neurofeedback in rehabilitation. In order to promote plasticity, a causal relation between intended actions (detected for example from the EEG) and the corresponding feedback should be established. This requires reliable detection of motor intentions. In this study, we propose a method to detect movements from EEG with limited latency. In a self-paced asynchronous BCI paradigm, the initial negative phase of the movement-related cortical potentials (MRCPs), extracted from multi-channel scalp EEG was used to detect motor execution/imagination in healthy subjects and stroke patients. For MRCP detection, it was demonstrated that a new optimized spatial filtering technique led to better accuracy than a large Laplacian spatial filter and common spatial pattern. With the optimized spatial filter, the true positive rate (TPR) for detection of movement execution in healthy subjects (n = 15) was 82.5 ± 7.8%, with latency of -66.6 ± 121 ms. Although TPR decreased with motor imagination in healthy subject (n = 10, 64.5 ± 5.33%) and with attempted movements in stroke patients (n = 5, 55.01 ± 12.01%), the results are promising for the application of this approach to provide patient-driven real-time neurofeedback.

  15. Mesoscale infraslow spontaneous membrane potential fluctuations recapitulate high-frequency activity cortical motifs.

    Science.gov (United States)

    Chan, Allen W; Mohajerani, Majid H; LeDue, Jeffrey M; Wang, Yu Tian; Murphy, Timothy H

    2015-07-20

    Neuroimaging of spontaneous, resting-state infraslow (regional connectivity that are analogous to cortical motifs observed from higher-frequency spontaneous activity and reflect the underlying framework of intracortical axonal projections.

  16. Effect of weight-bearing exercise and calcium supplement on cortical and trabecular bone in the proximal tibia metaphyseal- an experimental protocol in ovariectomized rats

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    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

  17. Cortical field potentials preceding self-paced forelimb movements and influences of cerebellectomy upon them in rats.

    Science.gov (United States)

    Ohishi, Hiroko; Ichikawa, Jun; Matsuzaki, Ryuichi; Kyuhou, Shin ichi; Matsuura-Nakao, Kazuko; Seki, Tomomi; Gemba, Hisae

    2003-11-27

    Seven rats were well trained to move lever to the left by right forelimb at self-pace (self-paced forelimb movements). Cortical field potentials associated with self-paced forelimb movements were recorded by electrodes implanted chronically on the surface and at a 2.0 mm depth in the forelimb motor cortex on the left side. A surface-negative, depth-positive potential starting about 1.0 s prior to the movement was recorded in the rostral part of the forelimb motor cortex. Further we found that the premovement potential was eliminated by the cerebellar hemispherectomy on the right side. This suggests the participation of the cerebellar hemisphere in preparing the activity of the motor cortex before self-paced forelimb movements in rats, by cerebello-thalamo-cortical projections.

  18. Histomorphometric Assessment of Cancellous and Cortical Bone Material Distribution in the Proximal Humerus of Normal and Osteoporotic Individuals: Significantly Reduced Bone Stock in the Metaphyseal and Subcapital Regions of Osteoporotic Individuals.

    Science.gov (United States)

    Sprecher, Christoph M; Schmidutz, Florian; Helfen, Tobias; Richards, R Geoff; Blauth, Michael; Milz, Stefan

    2015-12-01

    Osteoporosis is a systemic disorder predominantly affecting postmenopausal women but also men at an advanced age. Both genders may suffer from low-energy fractures of, for example, the proximal humerus when reduction of the bone stock or/and quality has occurred.The aim of the current study was to compare the amount of bone in typical fracture zones of the proximal humerus in osteoporotic and non-osteoporotic individuals.The amount of bone in the proximal humerus was determined histomorphometrically in frontal plane sections. The donor bones were allocated to normal and osteoporotic groups using the T-score from distal radius DXA measurements of the same extremities. The T-score evaluation was done according to WHO criteria. Regional thickness of the subchondral plate and the metaphyseal cortical bone were measured using interactive image analysis.At all measured locations the amount of cancellous bone was significantly lower in individuals from the osteoporotic group compared to the non-osteoporotic one. The osteoporotic group showed more significant differences between regions of the same bone than the non-osteoporotic group. In both groups the subchondral cancellous bone and the subchondral plate were least affected by bone loss. In contrast, the medial metaphyseal region in the osteoporotic group exhibited higher bone loss in comparison to the lateral side.This observation may explain prevailing fracture patterns, which frequently involve compression fractures and certainly has an influence on the stability of implants placed in this medial region. It should be considered when planning the anchoring of osteosynthesis materials in osteoporotic patients with fractures of the proximal humerus.

  19. Compressive mechanical compatibility of anisotropic porous Ti6Al4V alloys in the range of physiological strain rate for cortical bone implant applications.

    Science.gov (United States)

    Li, Fuping; Li, Jinshan; Kou, Hongchao; Huang, Tingting; Zhou, Lian

    2015-09-01

    Porous titanium and its alloys are believed to be promising materials for bone implant applications, since they can reduce the "stress shielding" effect by tailoring porosity and improve fixation of implant through bone ingrowth. In the present work, porous Ti6Al4V alloys for biomedical application were fabricated by diffusion bonding of alloy meshes. Compressive mechanical behavior and compatibility in the range of physiological strain rate were studied under quasi-static and dynamic conditions. The results show that porous Ti6Al4V alloys possess anisotropic structure with elongated pores in the out-of-plane direction. For porous Ti6Al4V alloys with 60-70 % porosity, more than 40 % pores are in the range of 200-500 μm which is the optimum pore size suited for bone ingrowth. Quasi-static Young's modulus and yield stress of porous Ti6Al4V alloys with 30-70 % relative density are in the range of 6-40 GPa and 100-500 MPa, respectively. Quasi-static compressive properties can be quantitatively tailored by porosity to match those of cortical bone. Strain rate sensitivity of porous Ti6Al4V alloys is related to porosity. Porous Ti6Al4V alloys with porosity higher than 50 % show enhanced strain rate sensitivity, which is originated from that of base materials and micro-inertia effect. Porous Ti6Al4V alloys with 60-70 % porosity show superior compressive mechanical compatibility in the range of physiological strain rate for cortical bone implant applications.

  20. 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.

  1. Stimulation artifact correction method for estimation of early cortico-cortical evoked potentials.

    Science.gov (United States)

    Trebaul, Lena; Rudrauf, David; Job, Anne-Sophie; Mălîia, Mihai Dragos; Popa, Irina; Barborica, Andrei; Minotti, Lorella; Mîndruţă, Ioana; Kahane, Philippe; David, Olivier

    2016-05-01

    Effective connectivity can be explored using direct electrical stimulations in patients suffering from drug-resistant focal epilepsies and investigated with intracranial electrodes. Responses to brief electrical pulses mimic the physiological propagation of signals and manifest as cortico-cortical evoked potentials (CCEP). The first CCEP component is believed to reflect direct connectivity with the stimulated region but the stimulation artifact, a sharp deflection occurring during a few milliseconds, frequently contaminates it. In order to recover the characteristics of early CCEP responses, we developed an artifact correction method based on electrical modeling of the electrode-tissue interface. The biophysically motivated artifact templates are then regressed out of the recorded data as in any classical template-matching removal artifact methods. Our approach is able to make the distinction between the physiological responses time-locked to the stimulation pulses and the non-physiological component. We tested the correction on simulated CCEP data in order to quantify its efficiency for different stimulation and recording parameters. We demonstrated the efficiency of the new correction method on simulations of single trial recordings for early responses contaminated with the stimulation artifact. The results highlight the importance of sampling frequency for an accurate analysis of CCEP. We then applied the approach to experimental data. The model-based template removal was compared to a correction based on the subtraction of the averaged artifact. This new correction method of stimulation artifact will enable investigators to better analyze early CCEP components and infer direct effective connectivity in future CCEP studies. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

  2. Electrophysiological potentials reveal cortical mechanisms for mental imagery, mental simulation, and grounded (embodied cognition

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    Haline E. Schendan

    2012-09-01

    Full Text Available Grounded cognition theory proposes that cognition, including meaning, is grounded in sensorimotor processing. The mechanism for grounding cognition is mental simulation, which is a type of mental imagery that re-enacts modal processing. To reveal top-down, cortical mechanisms for mental simulation of shape, event-related potentials were recorded to face and object pictures preceded by mental imagery of a picture. Mental imagery of the identical face or object (congruous condition facilitated not only categorical perception (VPP/N170 but also later visual knowledge (N3[00] complex and linguistic knowledge (N400 for faces more than objects, and strategic semantic analysis (late positive complex between 200 and 700 ms. The later effects resembled semantic congruity effects with pictures. Mental imagery also facilitated category decisions, as a P3(00 peaked earlier for congruous than incongruous (other category pictures, resembling the case when identical pictures repeat immediately. Thus mental imagery mimics semantic congruity and immediate repetition priming processes with pictures. Perception control results showed the opposite for faces and were in the same direction for objects: Perceptual repetition adapts (and so impairs processing of perceived faces from categorical perception onwards, but primes processing of objects during categorical perception, visual knowledge processes, and strategic semantic analysis. For both imagery and perception, differences between faces and objects support domain-specificity and indicate that cognition is grounded in modal processing. Altogether, this direct neural evidence reveals that top-down processes of mental imagery sustain an imagistic representation that mimics perception well enough to prime subsequent perception and cognition. This also suggests that automatic mental simulation of the visual shape of faces and objects operates between 200 and 400 ms, and strategic mental simulation operates between

  3. The effect of a concurrent cognitive task on cortical potentials evoked by unpredictable balance perturbations

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    Staines W Richard

    2004-05-01

    Full Text Available Abstract Background Although previous studies suggest that postural control requires attention and other cognitive resources, the central mechanisms responsible for this relationship remain unclear. To address this issue, we examined the effects of altered attention on cortical activity and postural responses following mechanical perturbations to upright stance. We hypothesized that cortical activity would be attenuated but not delayed when mechanical perturbations were applied during a concurrent performance of a cognitive task (i.e. when attention was directed away from the perturbation. We also hypothesized that these cortical changes would be accompanied by alterations in the postural response, as evidenced by increases in the magnitude of anteroposterior (AP centre of pressure (COP peak displacements and tibialis anterior (TA muscle activity. Healthy young adults (n = 7 were instructed to continuously track (cognitive task or not track (control task a randomly moving visual target using a hand-held joystick. During each of these conditions, unpredictable translations of a moving floor evoked cortical and postural responses. Scalp-recorded cortical activity, COP, and TA electromyographic (EMG measures were collected. Results Results revealed a significant decrease in the magnitude of early cortical activity (the N1 response, the first negative peak after perturbation onset during the tracking task compared to the control condition. More pronounced AP COP peak displacements and EMG magnitudes were also observed for the tracking task and were possibly related to changes in the N1 response. Conclusion Based on previous notions that the N1 response represents sensory processing of the balance disturbance, we suggest that the attenuation of the N1 response is an important central mechanism that may provide insight into the relationship between attention and postural control.

  4. Distribution of bone density and cortical thickness in the proximal femur and their association with hip fracture in postmenopausal women: a quantitative computed tomography study.

    Science.gov (United States)

    Yang, L; Udall, W J M; McCloskey, E V; Eastell, R

    2014-01-01

    The quantitative computed tomography (QCT) scans in an individually matched case-control study of women with hip fracture were analysed. There were widespread deficits in the femoral volumetric bone mineral density (vBMD) and cortical thickness of cases, and cortical vBMD and thickness discriminated hip fracture independently of BMD by dual-energy X-ray absorptiometry (DXA). Acknowledging the limitations of QCT associated with partial volume effects, we used QCT in an individually matched case-control study of women with hip fracture to better understand its structural basis. Fifty postmenopausal women (55-89 years) who had sustained hip fractures due to low-energy trauma underwent QCT scans of the contralateral hip within 3 months of the fracture. For each case, postmenopausal women, matched by age (±5 years), weight (±5 kg) and height (±5 cm), were recruited as controls. We quantified cortical, trabecular and integral vBMD and apparent cortical thickness (AppCtTh) in four quadrants of cross-sections along the length of the femoral head (FH), femoral neck (FN), intertrochanter and trochanter and examined their association with hip fracture. Women with hip or intracapsular (IC) fracture had significantly (p hip and IC fractures independent of hip areal BMD (aBMD). The combination of AppCtTh and trabecular or integral vBMD discriminated hip fracture, whereas the combination of FH and FN AppCtTh discriminated IC fracture significantly (p hip aBMD. Deficits in vBMD and AppCtTh in cases were widespread in the proximal femur, and cortical vBMD and AppCtTh discriminated hip fracture independently of aBMD by DXA.

  5. Motor area localization using fMRI-constrained cortical current density reconstruction of movement-related cortical potentials, a comparison with fMRI and TMS mapping.

    Science.gov (United States)

    Inuggi, Alberto; Filippi, Massimo; Chieffo, Raffaella; Agosta, Federica; Rocca, Maria A; González-Rosa, Javier J; Cursi, Marco; Comi, Giancarlo; Leocani, Letizia

    2010-01-13

    The localization of human hand primary motor area (M1) has been the object of several studies during the last decades. EEG source analysis, functional magnetic resonance imaging (fMRI) and focal transcranial magnetic stimulation (TMS) are non-invasive methods for localizing M1 with good accuracy compared to direct electrocorticography (ECoG) results. EEG sources were reconstructed with Cortical Current Density (CCD) method, allowing to evaluate simultaneous and distributed patterns of activation and to increase accuracy by constraining on information derived from fMRI (fMRI-CCD). The aim of this study was to compare the M1 contribution of movement-related cortical potentials (MRCP) with TMS and fMRI results and to test the effect of constraints strength, algorithm norm and localization methods over CCD reconstruction. Seven right-handed healthy subjects underwent 64-channel EEG recording of MRCP to right thumb movement, focal TMS mapping of the right abductor pollicis brevis muscle and fMRI during right hand movement. We found fMRI activations, EEG sources and TMS mapping corresponding to the anatomical landmark of the hand area in all subjects with fMRI and TMS center-of-gravity and in almost all subjects using fMRI-CCD with moderate constraint. A significant improvement was found using fMRI-CCD compared to CCD alone. This study confirms the usefulness of multimodal integration of fMRI, EEG and TMS in localizing M1 and the possibility to increase EEG spatial resolution using fMRI information.

  6. Efeito do enxerto ósseo corticoesponjoso na osteogênese em falha cortical ulnar de galinhas domésticas (Gallus domesticus Effect of cortico-cancellous bone grafting in osteogenisis of cortical ulnar failure of domestic chickens (Gallus domesticus

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    D.A. Balthazar

    2013-02-01

    Full Text Available O objetivo do estudo foi avaliar o efeito do enxerto ósseo corticoesponjoso na osteogênese em falha cortical ulnar de galinhas domésticas. Foram utilizadas 18 galinhas, com aproximadamente 70 semanas de idade e peso corpóreo médio de 2,5kg. Criou-se uma falha óssea na porção diafisária média da ulna em ambas as asas, sendo a direita utilizada como grupo-controle (grupo I e a esquerda como grupo-tratado (grupo II. As aves foram subdivididas aleatoriamente em quatro subgrupos de acordo com o período de observação (14, 35, 60 e 90 dias. No grupo II, dois fragmentos ósseos da carena do esterno foram retirados, seccionados e implantados na falha óssea. Ao término do período de observação de cada subgrupo, as aves foram abatidas com tiopental sódico para realização dos exames histopatológico e radiográfico post-mortem, com classificação dos resultados em escala semiquantitativa (escore. O grupo II demonstrou osteogênese mais evidente aos 35 e 90 dias de pós-cirúrgico (PThe aim of this survey was to evaluate the effect of cortico-cancellous bone grafting in osteogenesis in cortical ulnar failure in domestic chickens. Eighteen chickens weighing 2.5kg with approximately 70 weeks of age were used. A bone defect in the middle portion of the ulna shaft was created in both wings; the right wing in the control group (Group I and the left in the treated group (Group II. The birds were randomly divided into four subgroups according to the observation period (14, 35, 60 and 90 days. In group II, two bone fragments of the keel of the sternum were removed, sectioned and implanted in the bone defects. At the end of the observation period for each subgroup, the birds were euthanaized with sodium thiopental to perform the histopathological and radiographic postmortem, with ranking of results in a semi-quantitative scale (score. Group II showed a more evident osteogenisis at 35 and 90 days after surgery (P<0.05. In comparing both groups

  7. High-fat Diet Decreases Cancellous Bone Mass But Has No Effect on Cortical Bone Mass in the Tibia in Mice

    Science.gov (United States)

    Introduction: Body mass has a positive effect on bone mineral density and the strength. Whether mass derived from an obesity condition is beneficial to bone has not been established; neither have the mechanism by which obesity affects bone metabolism. The aim of this study was to examine the effects...

  8. Autologous grafts of double-strut fibular cortical bone plate to treat the fractures and defects of distal femur: a case report and review of literature

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    CHEN Xu

    2012-02-01

    Full Text Available 【Abstract】We reported a 23-year-old man who was involved in a high-speed motorcycle accident. He sustained a closed fracture at the right distal femur. The primary fracture happened on February 2008. He underwent open reduction and internal fixation with cloverleaf plate. And one hundred days after the surgery, the proximal screws were pulled-out, but the bone union was not achieved. Treatment consisted of exchanging the cloverleaf plate with a locking compression plate and using an auto-iliac bone graft to fill the nonunion gap. In July 2009, the patient had a sharp pain in the right lower limb. The X-ray revealed that the plate implanted last year was broken, causing a nonunion at the fracture site. Immediately the plate and screws were removed and an intramedullary nail was inserted reversely from the distal femur as well as a 7 cm long bone from the right fibula was extracted and longitudinally split into two pieces to construct cortical bone plates. Then we placed them laterally and medially to fracture site, drilled two holes respectively, and fastened them with suture. We carried on auto-iliac bone grafting with the nonunion bone grafts. The follow-up at 15 months after operation showed that the treatment was successful, X-ray confirmed that there was no rotation and no angular or short deformity. We briefly reviewed the literature regarding such an unusual presentation and discussed in details the possible etiology and the advantages of autologous double-strut fibular grafts to cope with such an intractable situation. Key words: Femur; Transplantation, autologous; Bone screws

  9. Age-related changes in collagen properties and mineralization in cancellous and cortical bone in the porcine mandibular condyle

    NARCIS (Netherlands)

    Willems, N.M.B.K.; Langenbach, G.E.J.; Everts, V.; Mulder, L.; Grünheid, T.; Bank, R.A.; Zentner, A.; Eijden, T.M.G.J. van

    2010-01-01

    Collagen is an important constituent of bone, and it has been suggested that changes in collagen and mineral properties of bone are interrelated during growth. The aim of this study was to quantify age-related changes in collagen properties and the degree of mineralization of bone (DMB). The DMB in

  10. Exploration of electric properties of bone compared to cement: streaming potential and piezoelectirc properties

    Science.gov (United States)

    Dry, Carolyn

    2015-03-01

    Bone is a material after which to model construction materials for many reasons, including its great strength, toughness, and adaptability. This paper focuses on bone's intrinsic ability to adapt to its environment, namely loading conditions. Research on bone's electrical properties reveals that two phenomena occur in bone to allow it to adapt to environmental changes; they are the inherent piezoelectric property of bone and the streaming potential of bone [1]. Together they create charge differences that attract ions to specific regions of the bone, namely those under greatest stress, in order to build up the region to handle the applied load. Research on the utilization of these properties in cement in order to increase adaptability was studied along with 1) the inherent electric properties of the cement itself and 2) considered the introduction of a different polymer or ceramic within the cement to impart piezoelectricity and streaming potential.

  11. Dendritic Na(+) spikes enable cortical input to drive action potential output from hippocampal CA2 pyramidal neurons.

    Science.gov (United States)

    Sun, Qian; Srinivas, Kalyan V; Sotayo, Alaba; Siegelbaum, Steven A

    2014-01-01

    Synaptic inputs from different brain areas are often targeted to distinct regions of neuronal dendritic arbors. Inputs to proximal dendrites usually produce large somatic EPSPs that efficiently trigger action potential (AP) output, whereas inputs to distal dendrites are greatly attenuated and may largely modulate AP output. In contrast to most other cortical and hippocampal neurons, hippocampal CA2 pyramidal neurons show unusually strong excitation by their distal dendritic inputs from entorhinal cortex (EC). In this study, we demonstrate that the ability of these EC inputs to drive CA2 AP output requires the firing of local dendritic Na(+) spikes. Furthermore, we find that CA2 dendritic geometry contributes to the efficient coupling of dendritic Na(+) spikes to AP output. These results provide a striking example of how dendritic spikes enable direct cortical inputs to overcome unfavorable distal synaptic locale to trigger axonal AP output and thereby enable efficient cortico-hippocampal information flow.

  12. Intrinsic mechanical behavior of femoral cortical bone in young, osteoporotic and bisphosphonate-treated individuals in low- and high energy fracture conditions

    Science.gov (United States)

    Zimmermann, Elizabeth A.; Schaible, Eric; Gludovatz, Bernd; Schmidt, Felix N.; Riedel, Christoph; Krause, Matthias; Vettorazzi, Eik; Acevedo, Claire; Hahn, Michael; Püschel, Klaus; Tang, Simon; Amling, Michael; Ritchie, Robert O.; Busse, Björn

    2016-02-01

    Bisphosphonates are a common treatment to reduce osteoporotic fractures. This treatment induces osseous structural and compositional changes accompanied by positive effects on osteoblasts and osteocytes. Here, we test the hypothesis that restored osseous cell behavior, which resembles characteristics of younger, healthy cortical bone, leads to improved bone quality. Microarchitecture and mechanical properties of young, treatment-naïve osteoporosis, and bisphosphonate-treated cases were investigated in femoral cortices. Tissue strength was measured using three-point bending. Collagen fibril-level deformation was assessed in non-traumatic and traumatic fracture states using synchrotron small-angle x-ray scattering (SAXS) at low and high strain rates. The lower modulus, strength and fibril deformation measured at low strain rates reflects susceptibility for osteoporotic low-energy fragility fractures. Independent of age, disease and treatment status, SAXS revealed reduced fibril plasticity at high strain rates, characteristic of traumatic fracture. The significantly reduced mechanical integrity in osteoporosis may originate from porosity and alterations to the intra/extrafibrillar structure, while the fibril deformation under treatment indicates improved nano-scale characteristics. In conclusion, losses in strength and fibril deformation at low strain rates correlate with the occurrence of fragility fractures in osteoporosis, while improvements in structural and mechanical properties following bisphosphonate treatment may foster resistance to fracture during physiological strain rates.

  13. Mid-thigh cortical bone structural parameters, muscle mass and strength, and association with lower limb fractures in older men and women (AGES-Reykjavik Study).

    Science.gov (United States)

    Johannesdottir, Fjola; Aspelund, Thor; Siggeirsdottir, Kristin; Jonsson, Brynjolfur Y; Mogensen, Brynjolfur; Sigurdsson, Sigurdur; Harris, Tamara B; Gudnason, Vilmundur G; Lang, Thomas F; Sigurdsson, Gunnar

    2012-05-01

    In a cross-sectional study we investigated the relationship between muscle and bone parameters in the mid-thigh in older people using data from a single axial computed tomographic section through the mid-thigh. Additionally, we studied the association of these variables with incident low-trauma lower limb fractures. A total of 3,762 older individuals (1,838 men and 1,924 women), aged 66-96 years, participants in the AGES-Reykjavik study, were studied. The total cross-sectional muscular area and knee extensor strength declined with age similarly in both sexes. Muscle parameters correlated most strongly with cortical area and total shaft area (adjusted for age, height, and weight) but explained lower limb fractures. Small muscular area, low knee extensor strength, large MA, low cortical thickness, and high BR were significantly associated with fractures in both sexes. Our results show that bone and muscle loss proceed at different rates and with different gender patterns.

  14. Self-organized two-state membrane potential transitions in a network of realistically modeled cortical neurons.

    Science.gov (United States)

    Kang, Siu; Kitano, Katsunori; Fukai, Tomoki

    2004-04-01

    Recent studies have revealed that in vivo cortical neurons show spontaneous transitions between two subthreshold levels of the membrane potentials, 'up' and 'down' states. The neural mechanism of generating those spontaneous states transitions, however, remains unclear. Recent electrophysiological studies have suggested that those state transitions may occur through activation of a hyperpolarization-activated cation current (H-current), possibly by inhibitory synaptic inputs. Here, we demonstrate that two-state membrane potential fluctuations similar to those exhibited by in vivo neurons can be generated through a spike-timing-dependent self-organizing process in a network of inhibitory neurons and excitatory neurons expressing the H-current.

  15. Autologous grafts of double-strut fibular cortical bone plate to treat the fractures and defects of distal femur: a case report and review of literature

    Institute of Scientific and Technical Information of China (English)

    CHEN Xu; LI Jian-jun; KONG Zhan; YANG Dong-xiang; YUAN Xiang-nan

    2011-01-01

    We reported a 23-year-old man who was involved in a high-speed motorcycle accident. He sustained a closed fracture at the right distal femur. The primary fracture happened on February 2008. He underwent open reduction and internal fixation with cloverleaf plate. And one hundred days after the surgery, the proximal screws were pulled-out, but the bone union was not achieved. Treat ment consisted of exchanging the cloverleaf plate with a locking compression plate and using an auto-iliac bone graft to fill the nonunion gap. In July 2009, the patient had a sharp pain in the right lower limb. The X-ray revealed that the plate implanted last year was broken, causing a nonunion at the fracture site. Immediately the plate and screws were removed and an intramedullary nail was inserted reversely from the distal femur as well as a 7 cm long bone from the right fibula was extracted and longitudinally split into two pieces to construct cortical bone plates. Then we placed them laterally and medially to fracture site, drilled two holes respectively, and fastened them with suture. We carried on auto-iliac bone grafting with the nonunion bone grafts. The follow-up at 15 months after operation showed that the treatment was successful, X-ray confirmed that there was no rotation and no angular or short deformity. We briefly reviewed the literature regarding such an unusual presentation and discussed in details the possible etiology and the advantages of autologous double-strut fibular grafts to cope with such an intractable situation.

  16. Fast (mainly 30-100 Hz) oscillations in the cat cerebellothalamic pathway and their synchronization with cortical potentials.

    Science.gov (United States)

    Timofeev, I; Steriade, M

    1997-01-01

    1. Intracellular recordings from 216 thalamocortical (TC) neurones in the ventrolateral (VL) nucleus of intact-cortex and decorticated cats under ketamine-xylazine anaesthesia revealed spontaneously occurring fast oscillations (mainly 30-100 Hz) in 86% of investigated cells. The fast depolarizing events consisted of excitatory postsynaptic potentials (EPSPs), giving rise to fast prepotentials (FPPs) in 22% of neurones, which eventually lead to full-blown action potentials. The frequency of fast events changed by factors of 2-5 in periods as short as 0.3-1.0 s. 2. The spontaneous oscillations were similar to responses evoked in VL relay neurones by stimuli to the afferent cerebellofugal axons in brachium conjunctivum (BC) and were strikingly reduced or abolished after electrolytic lesion of BC axons. 3. The amplitude and duration of fast depolarizing events were significantly reduced during the descending phase of the inhibitory postsynaptic potentials (IPSPs) in TC cells, related to spontaneous spindles or evoked by local thalamic stimulation. 4. Averaged field potentials recorded from motor cortex and triggered by EPSPs and/or action potentials of intracellularly recorded VL cells demonstrated that both spontaneous and BC-evoked fast depolarizations in VL relay neurones were coherent with fast rhythms in cortical area 4. 5. These results show that, in addition to the thalamic and cortical generation sites of the fast (so-called gamma) oscillations, prethalamic relay stations, such as deep cerebellar nuclei, are major contributors to the induction of fast rhythms which depend on the depolarization of thalamic and cortical neurones and which represent a hallmark of brain activation patterns. PMID:9350626

  17. Therapeutic potential of the novel hybrid molecule JM-20 against focal cortical ischemia in rats

    Directory of Open Access Journals (Sweden)

    Yanier Núñez Figueredo

    2016-08-01

    Full Text Available Context: Despite the great mortality and morbidity of stroke, treatment options remain limited. We previously showed that JM-20, a novel synthetic molecule, possessed a strong neuroprotective effect in rats subjected to transient middle cerebral artery occlusion. However, to verify the robustness of the pre-clinical neuroprotective effects of JM-20 to get good prognosis in the translation to the clinic, it is necessary to use other experimental models of brain ischemia. Aims: To evaluate the neuroprotective effects of JM-20 following the onset of permanent focal cerebral ischemia induced in rats by thermocoagulation of blood into pial blood vessels of cerebral cortices. Methods: Ischemic lesion was induced by thermocoagulation of blood into pial blood vessels of primary motor and somatosensory cortices. Behavioral performance was evaluated by the cylinder testing for a period of 2, 3 and 7 days after surgery, and was followed by histopathological study in brain cortex stained with hematoxylin- eosin. Results: Ischemic injury resulted in impaired function of the forelimb evidenced by high asymmetry punctuation, and caused histopathological alterations indicative of tissue damage at cerebral cortex. JM-20 treatment (4 and 8 mg/kg significantly decreased asymmetry scores and histological alterations with a marked preservation of cortical neurons. Conclusions: The effects of permanent brain ischemia were strongly attenuated by JM-20 administration, which expands and improves the current preclinical data of JM-20 as neuroprotector against cerebral ischemia, and strongly support the examination of its translation to the clinic to treat acute ischemic stroke.

  18. Fast volumetric imaging of bound and pore water in cortical bone using three-dimensional ultrashort-TE (UTE) and inversion recovery UTE sequences.

    Science.gov (United States)

    Chen, Jun; Carl, Michael; Ma, Yajun; Shao, Hongda; Lu, Xing; Chen, Bimin; Chang, Eric Y; Wu, Zhihong; Du, Jiang

    2016-10-01

    We report the three-dimensional ultrashort-TE (3D UTE) and adiabatic inversion recovery UTE (IR-UTE) sequences employing a radial trajectory with conical view ordering for bi-component T2 * analysis of bound water (T2 *(BW) ) and pore water (T2 *(PW) ) in cortical bone. An interleaved dual-echo 3D UTE acquisition scheme was developed for fast bi-component analysis of bound and pore water in cortical bone. A 3D IR-UTE acquisition scheme employing multiple spokes per IR was developed for bound water imaging. Two-dimensional UTE (2D UTE) and IR-UTE sequences were employed for comparison. The sequences were applied to bovine bone samples (n = 6) and volunteers (n = 6) using a 3-T scanner. Bi-component fitting of 3D UTE images of bovine samples showed a mean T2 *(BW) of 0.26 ± 0.04 ms and T2 *(PW) of 4.16 ± 0.35 ms, with fractions of 21.5 ± 3.6% and 78.5 ± 3.6%, respectively. The 3D IR-UTE signal showed a single-component decay with a mean T2 *(BW) of 0.29 ± 0.05 ms, suggesting selective imaging of bound water. Similar results were achieved with the 2D UTE and IR-UTE sequences. Bi-component fitting of 3D UTE images of the tibial midshafts of healthy volunteers showed a mean T2 *(BW) of 0.32 ± 0.08 ms and T2 *(PW) of 5.78 ± 1.24 ms, with fractions of 34.2 ± 7.4% and 65.8 ± 7.4%, respectively. Single-component fitting of 3D IR-UTE images showed a mean T2 *(BW) of 0.35 ± 0.09 ms. The 3D UTE and 3D IR-UTE techniques allow fast volumetric mapping of bound and pore water in cortical bone. Copyright © 2016 John Wiley & Sons, Ltd.

  19. Movement-related cortical activation with voluntary pinch task: simultaneous monitoring of near-infrared spectroscopy signals and movement-related cortical potentials

    Science.gov (United States)

    Sato, Yosuke; Fukuda, Masafumi; Oishi, Makoto; Fujii, Yukihiko

    2012-07-01

    This study was designed to evaluate hemodynamic and electrophysiological motor cortex responses to voluntary finger pinching in humans, with simultaneous recording of near-infrared spectroscopy (NIRS) signals and movement-related cortical potentials (MRCP). Six healthy, right-handed subjects performed 100 trials of voluntary right-thumb index-finger pinching with about a 10-second interval at their own pace. Throughout the session, 48 regions over the bilateral motor cortex were assessed by NIRS, while MRCP and electromyogram (EMG) were simultaneously monitored. MRCP started 1536+/-58 ms before EMG onset and peaked 127+/-24 ms after EMG onset. NIRS data showed bilateral prefrontal cortex at 0.5+/-0.1 s before EMG onset and bilateral dorsal premotor cortex activations at 0.6+/-0.1 s before EMG onset. The hand area of the sensorimotor cortex was activated left-dominantly, seen obviously peaked at 3.7+/-0.2 s after EMG onset. The comparison between MRCP and NIRS results raised the possibility that the vascular response to neural activity occurs within 4 s with a voluntary pinch task. These results indicate that our technique allows detailed study of the motor control. Our method is a promising strategy for event-related motor control and neurovascular coupling studies.

  20. Refraction changes during elevation of intraocular pressure by suction cup, their reflection in the pattern visual evoked cortical potential and their compensation.

    Science.gov (United States)

    Bernd, A; Ulrich, W D; Teubel, H; Rohrwacher, F; Barth, T

    1993-01-01

    Visual evoked cortical potential studies using pattern stimuli with the intraocular pressure raised artificially by the suction cup method have been reported. Possible changes in the refraction of the eye due to the method employed and their influence on the pattern visual evoked cortical potential have not been considered. Changes in the refraction of the eye during artificial intraocular pressure elevation and the influence of such changes on pattern visual evoked cortical potentials were studied. The refraction changes were found to depend on the shape of the suction cup. They could be compensated for by employing properly shaped suction cups and contact lenses. The behavior of amplitude and latency of the pattern visual evoked cortical potential at artificially elevated intraocular pressure with compensation for refraction changes has been studied and found to depend in a characteristic manner on ocular perfusion pressure.

  1. Stromal cell-derived factor-1 potentiates bone morphogenetic protein-2 induced bone formation.

    Science.gov (United States)

    Higashino, Kosaku; Viggeswarapu, Manjula; Bargouti, Maggie; Liu, Hui; Titus, Louisa; Boden, Scott D

    2011-02-01

    The mechanisms driving bone marrow stem cell mobilization are poorly understood. A recent murine study found that circulating bone marrow-derived osteoprogenitor cells (MOPCs) were recruited to the site of recombinant human bone morphogenetic protein-2 (BMP-2)-induced bone formation. Stromal cell-derived factor-1α (SDF-1α) and its cellular receptor CXCR4 have been shown to mediate the homing of stem cells to injured tissues. We hypothesized that chemokines, such as SDF-1, are also involved with mobilization of bone marrow cells. The CD45(-) fraction is a major source of MOPCs. In this report we determined that the addition of BMP-2 or SDF-1 to collagen implants increased the number of MOPCs in the peripheral blood. BMP-2-induced mobilization was blocked by CXCR4 antibody, confirming the role of SDF-1 in mobilization. We determined for the first time that addition of SDF-1 to implants containing BMP-2 enhances mobilization, homing of MOPCs to the implant, and ectopic bone formation induced by suboptimal BMP-2 doses. These results suggest that SDF-1 increases the number of osteoprogenitor cells that are mobilized from the bone marrow and then home to the implant. Thus, addition of SDF-1 to BMP-2 may improve the efficiency of BMPs in vivo, making their routine use for orthopaedic applications more affordable and available to more patients.

  2. Computed tomography to evaluate the association of fragmented heterolog cortical bone and methylmethacrylate to repare segmental bone defect produced in tibia of rabbits; Tomografia computadorizada da matriz ossea mineralizada heterologa fragmentada e metilmetacrilato na reparacao de falhas osseas segmentares produzidas em tibia de coelhos

    Energy Technology Data Exchange (ETDEWEB)

    Freitas, S.H. [Universidade Federal de Sao Paulo (USP), SP (Brazil); Doria, R.G.S. [Universidade Federal de Sao Paulo (USP), SP (Brazil). Faculdade de Zootecnia e Engenharia de Alimentos; Mendonca, F.S.; Santos, M.D.; Moreira, R. [Universidade de Cuiaba, MT (Brazil). Faculdade de Medicina Veterinaria; Simoes, R.S. [Universidade Federal de Sao Paulo (USP), SP (Brazil). Hospital Universitario; Camargo, L.M.; Simoes, M.J. [Universidade Federal de Sao Paulo (USP), SP (Brazil). Escola Paulista de Medicina; Marques, A.T.C. [Universidade de Cuiaba, MT (Brazil). Faculdade de Odontologia

    2012-11-15

    A 6mm segmental defect was performed on the metaphyseal region of the tibia of 12 rabbits and the autoclaved fragmented heterolog cortical bone conserved in glycerin (98%) and methylmethacrylate was used as a bone graft for the reconstruction. The graft was placed in the receptor bed and its integration was evaluated by computed tomography after 30, 60 and 90 days. There was gradual bone graft incorporation in the receptor bed during the time in 100% of the cases. Fragmented cortical bone heterograft and methylmethacrylate was biologically compatible and promotes bone defect reparation without signs of infection, migration and or rejection, featuring a new option of osseous substitute to fill in bone defects. (author)

  3. Three-dimensional reconstruction of Haversian systems in human cortical bone using synchrotron radiation-based micro-CT: morphology and quantification of branching and transverse connections across age.

    Science.gov (United States)

    Maggiano, Isabel S; Maggiano, Corey M; Clement, John G; Thomas, C David L; Carter, Yasmin; Cooper, David M L

    2016-05-01

    This study uses synchrotron radiation-based micro-computed tomography (CT) scans to reconstruct three-dimensional networks of Haversian systems in human cortical bone in order to observe and analyse interconnectivity of Haversian systems and the development of total Haversian networks across different ages. A better knowledge of how Haversian systems interact with each other is essential to improve understanding of remodeling mechanisms and bone maintenance; however, previous methodological approaches (e.g. serial sections) did not reveal enough detail to follow the specific morphology of Haversian branching, for example. Accordingly, the aim of the present study was to identify the morphological diversity of branching patterns and transverse connections, and to understand how they change with age. Two types of branching morphologies were identified: lateral branching, resulting in small osteon branches bifurcating off of larger Haversian canals; and dichotomous branching, the formation of two new osteonal branches from one. The reconstructions in this study also suggest that Haversian systems frequently target previously existing systems as a path for their course, resulting in a cross-sectional morphology frequently referred to as 'type II osteons'. Transverse connections were diverse in their course from linear to oblique to curvy. Quantitative assessment of age-related trends indicates that while in younger human individuals transverse connections were most common, in older individuals more evidence of connections resulting from Haversian systems growing inside previously existing systems was found. Despite these changes in morphological characteristics, a relatively constant degree of overall interconnectivity is maintained throughout life. Altogether, the present study reveals important details about Haversian systems and their relation to each other that can be used towards a better understanding of cortical bone remodeling as well as a more accurate

  4. A longitudinal HR‐pQCT study of alendronate treatment in postmenopausal women with low bone density: Relations among density, cortical and trabecular microarchitecture, biomechanics, and bone turnover

    National Research Council Canada - National Science Library

    Burghardt, Andrew J; Kazakia, Galateia J; Sode, Miki; de Papp, Anne E; Link, Thomas M; Majumdar, Sharmila

    2010-01-01

    The goal of this study was to characterize longitudinal changes in bone microarchitecture and function in women treated with an established antifracture therapeutic. In this double‐blind, placebo...

  5. Simultaneously-evoked auditory potentials (SEAP): A new method for concurrent measurement of cortical and subcortical auditory-evoked activity.

    Science.gov (United States)

    Slugocki, Christopher; Bosnyak, Daniel; Trainor, Laurel J

    2017-03-01

    Recent electrophysiological work has evinced a capacity for plasticity in subcortical auditory nuclei in human listeners. Similar plastic effects have been measured in cortically-generated auditory potentials but it is unclear how the two interact. Here we present Simultaneously-Evoked Auditory Potentials (SEAP), a method designed to concurrently elicit electrophysiological brain potentials from inferior colliculus, thalamus, and primary and secondary auditory cortices. Twenty-six normal-hearing adult subjects (mean 19.26 years, 9 male) were exposed to 2400 monaural (right-ear) presentations of a specially-designed stimulus which consisted of a pure-tone carrier (500 or 600 Hz) that had been amplitude-modulated at the sum of 37 and 81 Hz (depth 100%). Presentation followed an oddball paradigm wherein the pure-tone carrier was set to 500 Hz for 85% of presentations and pseudo-randomly changed to 600 Hz for the remaining 15% of presentations. Single-channel electroencephalographic data were recorded from each subject using a vertical montage referenced to the right earlobe. We show that SEAP elicits a 500 Hz frequency-following response (FFR; generated in inferior colliculus), 80 (subcortical) and 40 (primary auditory cortex) Hz auditory steady-state responses (ASSRs), mismatch negativity (MMN) and P3a (when there is an occasional change in carrier frequency; secondary auditory cortex) in addition to the obligatory N1-P2 complex (secondary auditory cortex). Analyses showed that subcortical and cortical processes are linked as (i) the latency of the FFR predicts the phase delay of the 40 Hz steady-state response, (ii) the phase delays of the 40 and 80 Hz steady-state responses are correlated, and (iii) the fidelity of the FFR predicts the latency of the N1 component. The SEAP method offers a new approach for measuring the dynamic encoding of acoustic features at multiple levels of the auditory pathway. As such, SEAP is a promising tool with which to study how

  6. Delayed effects of corticosterone on slow after-hyperpolarization potentials in mouse hippocampal versus prefrontal cortical pyramidal neurons.

    Directory of Open Access Journals (Sweden)

    Anup G Pillai

    Full Text Available The rodent stress hormone corticosterone changes neuronal activity in a slow and persistent manner through transcriptional regulation. In the rat dorsal hippocampus, corticosterone enhances the amplitude of calcium-dependent potassium currents that cause a lingering slow after-hyperpolarization (sAHP at the end of depolarizing events. In this study we compared the putative region-dependency of the delayed effects of corticosterone (approximately 5 hrs after treatment on sAHP as well as other active and passive properties of layer 2/3 pyramidal neurons from three prefrontal areas, i.e. the lateral orbitofrontal, prelimbic and infralimbic cortex, with the hippocampus of adult mice. In agreement with previous studies, corticosterone increased sAHP amplitude in the dorsal hippocampus with depolarizing steps of increasing amplitude. However, in the lateral orbitofrontal, prelimbic and infralimbic cortices we did not observe any modifications of sAHP amplitude after corticosterone treatment. Properties of single action potentials or % ratio of the last spike interval with respect to the first spike interval, an indicator of accommodation in an action potential train, were not significantly affected by corticosterone in all brain regions examined. Lastly, corticosterone treatment did not induce any lasting changes in passive membrane properties of hippocampal or cortical neurons. Overall, the data indicate that corticosterone slowly and very persistently increases the sAHP amplitude in hippocampal pyramidal neurons, while this is not the case in the cortical regions examined. This implies that changes in excitability across brain regions reached by corticosterone may vary over a prolonged period of time after stress.

  7. Cortical configuration by stimulus onset visual evoked potentials (SO-VEPs) predicts performance on a motion direction discrimination task.

    Science.gov (United States)

    Zalar, Bojan; Martin, Tim; Kavcic, Voyko

    2015-06-01

    The slowing of information processing, a hallmark of cognitive aging, has several origins. Previously we reported that in a motion direction discrimination task, older as compared to younger participants showed prolonged non-decision time, an index of an early perceptual stage, while in motion onset visual evoked potentials (MO-VEPs) the P1 component was enhanced and N2 was diminished. We did not find any significant correlations between behavioral and MO-VEP measures. Here, we investigated the role of age in encoding and perceptual processing of stimulus onset visually evoked potentials (SO-VEPs). Twelve healthy adults (age55years) performed a motion direction discrimination task during EEG recording. Prior to motion, the stimulus consisted of a static cloud of white dots on a black background. As expected, SO-VEPs evoked well defined P1, N1, and P2 components. Elderly participants as compared to young participants showed increased P1 amplitude while their P2 amplitude was reduced. In addition elderly participants showed increased latencies for P1 and N1 components. Contrary to the findings with MO-VEPs, SO-VEP parameters were significant predictors of average response times and diffusion model parameters. Our electrophysiological results support the notion that slowing of information processing in older adults starts at the very beginning of encoding in visual cortical processing, most likely in striate and extrastriate visual cortices. More importantly, the earliest SO-VEP components, possibly reflecting configuration of visual cortices and encoding processes, predict subsequent prolonging and tardiness of perceptual and higher-level cognitive processes.

  8. Patterson-Lowry rhizomelic dysplasia: a potentially lethal bone dysplasia?

    Energy Technology Data Exchange (ETDEWEB)

    Kamoda, T.; Nakajima, R.; Matsui, A. [Dept. of Paediatrics, Univ. of Tsukuba, Ibaraki (Japan); Nishimura, G. [Dept. of Radiology, Nasu Chuou Hospital, Tochigi (Japan)

    2001-02-01

    We report a Japanese boy, who is considered as having Patterson-Lowry rhizomelic dysplasia, a rare, as yet undefined, skeletal dysplasia. The diagnosis was warranted by the constellation of skeletal abnormalities - mild platyspondyly, hypoplastic ilia, broad proximal femora with prominent lesser trochanters, mild brachymetacarpalia and, most importantly, rhizomelic shortening of the upper limbs with lateral bowing, medial cortical thickening, and medial metaphyseal notching of the humeri. Our patient, unlike previously reported patients, had respiratory distress and died suddenly of unknown cause in late infancy. Our experience may imply the heterogeneity or phenotypic variability of Patterson-Lowry rhizomelic dysplasia. (orig.)

  9. Influence of short-term fixation with mixed formalin or ethanol solution on the mechanical properties of human cortical bone

    OpenAIRE

    Mick E.; Steinke H.; Wolfskämpf T.; Wieding J.; Hammer N.; Schulze M.; Souffrant R.; Bader R.

    2015-01-01

    Bone specimens obtained for biomechanical experiments are fresh-frozen for storage to slow down tissue degradation and autolysis in long-term storage. Alternatively, due to infectious risks related to the fresh tissues, fixative agents are commonly used. However, fixatives will likely change the mechanical properties of bone. Existing studies on this issue gave controversial results that are hardly comparable due to a variety of measurement approaches. For this reason, the influence of ethano...

  10. Probing physical and chemical changes in cortical bone due to osteoporosis and type 2 diabetes by solid-state NMR

    Science.gov (United States)

    Zhou, Donghua; Taylor, Amanda; Rendina, Beth; Smith, Brenda; Department of Physics Collaboration; Department of Nutritional Sciences Collaboration

    2013-03-01

    Approximately 1.5 million fractures occur each year in the U.S. due to osteoporosis, which is characterized by decreased bone mineral density and deterioration of bone micro-architecture. On the other hand, type 2 diabetes also significantly increases fracture risks, despite having a normal or even higher bone mineral density. Solid-state NMR has been applied to bone tissues from normal and disease-inflicted mouse models to study structural and chemical dynamics as the disease progresses. Proton relaxation experiments were performed to measure water populations in the bone matrix and pores. Collagen-bound water has strong influence on bone resilience, while water content in the pores reveals amount and size of pores from micro- to millimeter range. Other biochemical and atomic-scale structural alterations in the mineral and organic phases and their interface were investigated by proton, phosphorus, and carbon NMR spectroscopy. Experiments were designed to individually detect different types of phosphorus environments: near the mineral surface, similar to hydroxyapatite, and deficient of hydrogens due to substitution of the hydroxyl group by other ions. A new method was also developed for accurate quantification of each phosphorus species. The authors appreciate financial support for this project from the College of Human Sciences and the College of Arts and Sciences, Oklahoma State University.

  11. Ethylene oxide gas sterilization does not reduce the osteoinductive potential of demineralized bone in rats

    DEFF Research Database (Denmark)

    Solheim, E; Pinholt, E M; Bang, G

    1995-01-01

    It has been shown that different sterilization procedures of demineralized bone may influence its osteoinductive properties. The aim of this study was to evaluate the effect of ethylene oxide sterilization for 1, 3, and 6 hours on the osteoinductive potential of allogeneic demineralized bone...... without prior sterilization of the material, whereas the demineralized bone implanted in Groups B, C, and D had been sterilized in ethylene oxide gas for 1, 3, or 6 hours, respectively, and aerated for 48 hours. At 4 weeks postoperatively, bone formation was evaluated quantitatively by strontium 85 uptake...

  12. AST-induced bone loss in men with prostate cancer: exercise as a potential countermeasure.

    Science.gov (United States)

    Bolam, K A; Galvão, D A; Spry, N; Newton, R U; Taaffe, D R

    2012-12-01

    Androgen suppression treatment (AST) for men with prostate cancer is associated with a number of treatment-related side effects including an accelerated rate of bone loss. This loss of bone is greatest within the first year of AST and increases the risk for fracture. Pharmaceutical treatment in the form of bisphosphonates is currently used to counter the effects of hormone suppression on bone but is costly and associated with potential adverse effects. Recently, exercise has been shown to be an important adjuvant therapy to manage a range of treatment-related toxicities and enhance aspects of quality of life for men receiving AST. We propose that physical exercise may also have an important role in not only attenuating the bone loss associated with AST but in improving bone health and reducing fracture risk. In this review, the rationale underlying exercise as a countermeasure to AST-induced bone loss is provided.

  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. Orchidectomy-induced alterations in volumetric bone density, cortical porosity and strength of femur are attenuated by dietary conjugated linoleic acid in aged guinea pigs.

    Science.gov (United States)

    DeGuire, Jason R; Mak, Ivy L; Lavery, Paula; Agellon, Sherry; Wykes, Linda J; Weiler, Hope A

    2015-04-01

    Age-related osteoporosis and sarcopenia are ascribed in part to reductions in anabolic hormones. Dietary conjugated linoleic acid (CLA) improves lean and bone mass, but its impact during androgen deficiency is not known. This study tested if CLA would attenuate the effects of orchidectomy (ORX)-induced losses of bone and lean tissue. Male guinea pigs (n=40; 70-72 weeks), were randomized into four groups: (1) SHAM+Control diet, (2) SHAM+CLA diet, (3) ORX+Control diet, (4) ORX+CLA diet. Baseline blood sampling and dual-energy X-ray absorptiometry (DXA) scans were conducted, followed by surgery 4 days later with the test diets started 7 days after baseline sampling. Serial blood sampling and DXA scans were repeated 2, 4, 8 and 16 weeks on the test diets. Body composition and areal BMD (aBMD) of whole body, lumbar spine, femur and tibia were measured using DXA. At week 16, muscle protein fractional synthesis rate (FSR), volumetric BMD (vBMD), microarchitecture and bone strength were assessed. Body weight declined after SHAM and ORX surgery, with slower recovery in the ORX group. Dietary CLA did not affect weight or lean mass, but attenuated gains in fat mass. Lean mass was stable in SHAM and reduced in ORX by 2 weeks with whole body and femur bone mineral content (BMC) reduced by 4 weeks; CLA did not alter BMC. By week 16 ORX groups had lower free testosterone and myofibrillar FSR, yet higher cortisol, osteocalcin and ionized calcium with no alterations due to CLA. ORX+Control had higher prostaglandin E2 (PGE2) and total alkaline phosphatase compared to SHAM+Control whereas ORX+CLA were not different from SHAM groups. Femur metaphyseal vBMD was reduced in ORX+CTRL with the reduction attenuated by CLA. Femur cortical thickness (Ct.Th.) and biomechanical strength were reduced and cortical porosity (Ct.Po.) elevated by ORX and attenuated by CLA. This androgen deficient model with a sarcopenic-osteoporotic phenotype similar to aging men responded to dietary CLA with

  15. Deciphering seasonal variations in the diet and drinking water of modern White-Tailed deer by in situ analysis of osteons in cortical bone

    Science.gov (United States)

    Larson, T. E.; Longstaffe, F. J.

    2007-12-01

    In situ carbon and oxygen isotope values for bioapatite were obtained from longitudinal slices of cortical bone from modern domesticated sheep and free-range White-Tailed deer. The analyses were obtained using an IR-laser coupled to a GC-IRMS interface. Ablation pits averaged 200 × 50 μm, making it possible to sample individual or small bundles of osteons. Cortical bone is remodeled along osteons throughout a mammal's life. Therefore, data at this scale can record seasonal variations in diet and drinking water during the adult stages of a mammal, whereas teeth provide may provide information about the juvenile years of a mammal. Average δ18O and δ13C values for the sheep from southwestern Ontario, Canada, were 14.0 and -16.1‰, respectively. No trend was observed in the isotopic composition of the sheep's osteons, consistent with its constant diet and water supply. The δ18O (14.2 to 16.6‰) and δ13C (-19.2 to -15.6‰) values of osteons from White-Tailed deer from nearby Pinery Provincial Park, however, varied systematically and were negatively correlated. Oxygen isotope values of the osteons correlated well with changes in the δ18O values of the main water source for these deer: winter average, -10.7‰; summer average, -8.6‰. The variation in δ13C values of the osteons reflects changes in diet; summer diet consisted mainly of leafy C3 vegetation (-28.4‰), whereas winter diet comprised bark (-25.6‰), C4 grasses (δ13C, -12.7‰), and corn stalks and husks (-11.3‰).

  16. Effects of repetitive loading on the growth-induced changes in bone mass and cortical bone geometry: a 12-month study in pre/peri- and postmenarcheal tennis players.

    Science.gov (United States)

    Ducher, Gaele; Bass, Shona L; Saxon, Leanne; Daly, Robin M

    2011-06-01

    Pre- and early puberty may be the most opportune time to strengthen the female skeleton, but there are few longitudinal data to support this claim. Competitive female premenarcheal (pre/peri, n = 13) and postmenarcheal (post, n = 32) tennis players aged 10 to 17 years were followed over 12 months. The osteogenic response to loading was studied by comparing the playing and nonplaying humeri for dual-energy X-ray absorptiometry (DXA) bone mineral content (BMC) and magnetic resonance imaging (MRI) total bone area (ToA), medullary area (MedA), cortical area (CoA), and muscle area (MCSA) at the humerus. Over 12 months, growth-induced gains (nonplaying arm) in BMC, ToA, and CoA were greater in pre/peri (10% to 19%, p < .001) than in post (3% to 5%, p < .05 to .001) players. At baseline, BMC, ToA, CoA, and MCSA were 8% to 18% greater in the playing versus nonplaying arms in pre/peri and post players (all p < .001); MedA was smaller in the playing versus nonplaying arms in post only players (p < .05). When comparing the annual gains in the playing arm relative to changes in the nonplaying arm, the increases in ToA and CoA were greater in pre/peri than post players (all p < .05). The smaller the side-to-side differences in BMC and CoA at baseline, the larger the exercise benefits at 12 months (r = -0.39 to -0.48, p < .01). The exercise-induced change in MCSA was predictive of the exercise benefits in BMC in pre/peri players only (p < .05). In conclusion, both pre/peri- and postmenarcheal tennis players showed significant exercise-induced skeletal benefits within a year, with greater benefits in cortical bone geometry in pre/perimenarcheal girls.

  17. Bone marrow concentrate for autologous transplantation in minipigs. Characterization and osteogenic potential of mesenchymal stem cells.

    Science.gov (United States)

    Herten, M; Grassmann, J P; Sager, M; Benga, L; Fischer, J C; Jäger, M; Betsch, M; Wild, M; Hakimi, M; Jungbluth, P

    2013-01-01

    Autologous bone marrow plays an increasing role in the treatment of bone, cartilage and tendon healing disorders. Cell-based therapies display promising results in the support of local regeneration, especially therapies using intra-operative one-step treatments with autologous progenitor cells. In the present study, bone marrow-derived cells were concentrated in a point-of-care device and investigated for their mesenchymal stem cell (MSC) characteristics and their osteogenic potential. Bone marrow was harvested from the iliac crest of 16 minipigs. The mononucleated cells (MNC) were concentrated by gradient density centrifugation, cultivated, characterized by flow cytometry and stimulated into osteoblasts, adipocytes, and chondrocytes. Cell differentiation was investigated by histological and immunohistological staining of relevant lineage markers. The proliferation capacity was determined via colony forming units of fibroblast and of osteogenic alkaline-phosphatase-positive-cells. The MNC could be enriched 3.5-fold in nucleated cell concentrate in comparison to bone marrow. Flow cytometry analysis revealed a positive signal for the MSC markers. Cells could be differentiated into the three lines confirming the MSC character. The cellular osteogenic potential correlated significantly with the percentage of newly formed bone in vivo in a porcine metaphyseal long-bone defect model. This study demonstrates that bone marrow concentrate from minipigs display cells with MSC character and their osteogenic differentiation potential can be used for osseous defect repair in autologous transplantations.

  18. Mechanically-induced osteogenesis in the cortical bone of pre- to peripubertal stage and peri- to postpubertal stage mice

    Directory of Open Access Journals (Sweden)

    Plochocki Jeffrey H

    2009-06-01

    Full Text Available Abstract Background Exercise during postnatal development plays a key role in determining adult bone mass and reducing the risk of fracture and osteoporosis later in life. However, the relationship between mechanically-induced osteogenesis and age is unclear. Elevated levels of estrogen during puberty may inhibit periosteal bone formation. Thus, magnitudes of mechanically-induced osteogenesis may be vary with pubertal state. Methods The present study uses a murine model to examine age-related changes in bone formation at the femoral midshaft with voluntary exercise. Pre- to peripubertal mice aged 3 weeks and peri- to postpubertal mice aged 7 weeks were randomly divided into sedentary and exercised groups and subjected to histomorphometric comparison after 4 weeks of treatment. Results Results of the experiment indicate that exercise significantly increased osteogenesis on the periosteal and endocortical surface of the mice in the older age group (P P Conclusion These findings suggest that the amount and location of mechanically-induced osteogenesis differs by age during skeletal development. Late adolescence may be the optimal time to accrue bone mass and maximize bone strength.

  19. Bone Marrow Stem Cell as a Potential Treatment for Diabetes

    Directory of Open Access Journals (Sweden)

    Ming Li

    2013-01-01

    Full Text Available Diabetes mellitus (DM is a group of metabolic diseases in which a person has high blood glucose levels resulting from defects in insulin secretion and insulin action. The chronic hyperglycemia damages the eyes, kidneys, nerves, heart, and blood vessels. Curative therapies mainly include diet, insulin, and oral hypoglycemic agents. However, these therapies fail to maintain blood glucose levels in the normal range all the time. Although pancreas or islet-cell transplantation achieves better glucose control, a major obstacle is the shortage of donor organs. Recently, research has focused on stem cells which can be classified into embryonic stem cells (ESCs and tissue stem cells (TSCs to generate functional β cells. TSCs include the bone-marrow-, liver-, and pancreas-derived stem cells. In this review, we focus on treatment using bone marrow stem cells for type 1 and 2 DM.

  20. Mecânica e microbiologia de placas produzidas a partir de osso cortical bovino, conservadas em diferentes meios Mechanic and microbiology of plates produced from bovine cortical bone, conserved in several means

    Directory of Open Access Journals (Sweden)

    Edson Vilela de Melo Filho

    2011-04-01

    Full Text Available Objetivou-se com este trabalho avaliar a resistência mecânica de placas ósseas produzidas a partir de osso cortical bovino, conservadas em diferentes meios, e a eficiência desses meios em inibir o crescimento de microrganismos. Foram utilizadas 168 placas confeccionadas a partir de tíbia bovina e conservadas em glicerina a 98%, solução salina a 150%, solução de açúcar a 300%, líquido de Dakin, congeladas em N2L a -196°C, ou esterilizadas em óxido de etileno. Após reidratação em solução de cloreto de sódio a 0,9% por seis horas, elas foram submetidas a ensaios mecânicos de tração, compressão, flexão e torção. Foi realizada avaliação microbiológica das placas anterior e imediatamente após a reidratação, com ou sem adição de enrofloxacina a 0,5%. Não se observou diferença significativa (PThe objective of this study was to evaluate the mechanical strength of bone plates yielded from bovine cortical bone, conserved in different solutions, and the efficiency of these solutions in the inhibition of microorganism's growth. A hundred and sixty eight plates yielded from bovine tibiae were conserved in 98% glycerin, 150% saline solution, 300% sugar solution, Dakin solution, frozen in N2L at - 196°C, or sterilized in ethylene oxide gas. After rehydration in NaCl 0.9% solution for six hours, plates were subjected to tensile, compression, bending and twisting testing. The microbiological evaluation of bone plates was s carried out before and immediately after rehydration, with or without enrofloxacin 0.5% addition. There was no significant difference (P<0.01% on resistance to the rupture point in plates conserved in different solutions, frozen-thawed or sterilized. Microorganisms were isolated from plates conserved in satured salt solution, sugar satured solution, Dakin solution or frozen in N2L, before and after rehydraion However, after the use of NaCl 0.9% solution added of enrofloxacin 0.5%, microorganisms were not

  1. Comparison of Sensory-motor Rhythm and Movement Related Cortical Potential during Ballistic and Repetitive Motor Imagery

    Institute of Scientific and Technical Information of China (English)

    XU Ren; JIANG Ning; MRACHACZ-KERSTING Natalie; DREMSTRUP Kim; FARINA Dario

    2014-01-01

    In this study, we compared two types of EEG modalities, sensory-motor rhythms (SMR) and movement related cortical potentials (MRCP), on four healthy subjects performing ballistic or repetitive movement imagination. The EEG waveform morphology across subjects was similar for MRCPs, whereas there was not a clear pattern for SMRs. The rank-sum test showed a significant difference between the amplitude of baseline and that of the MRCP as early as 2 s prior to imagery onset, for both types of motor imageries, indicating strong discriminative power of MRCPs for predicting movement onset. For SMR, this type of discriminative power was relatively weak and highly subject-specific. On the other hand, the SMR landscape under the two movement imagery types was distinctive, holding a potential for discriminating the two movement imagery types. These preliminary results presented different characteristics of SMR and MRCP under different motor imageries, providing valuable information regarding the design and implementation of motor imagery based on BCI system.

  2. Vestibular evoked potentials (VsEPs) of cortical origin produced by impulsive acceleration applied at the nasion.

    Science.gov (United States)

    Todd, Neil P M; McLean, Aisha; Paillard, Aurore; Kluk, Karolina; Colebatch, James G

    2014-12-01

    We report the results of a study to record vestibular evoked potentials (VsEPs) of cortical origin produced by impulsive acceleration (IA). In a sample of 12 healthy participants, evoked potentials recorded by 70 channel electroencephalography were obtained by IA stimulation at the nasion and compared with evoked potentials from the same stimulus applied to the forefingers. The nasion stimulation gave rise to a series of positive and negative deflections in the latency range of 26-72 ms, which were dependent on the polarity of the applied IA. In contrast, evoked potentials from the fingers were characterised by a single N50/P50 deflection at about 50 ms and were polarity invariant. Source analysis confirmed that the finger evoked potentials were somatosensory in origin, i.e. were somatosensory evoked potentials, and suggested that the nasion evoked potentials plausibly included vestibular midline and frontal sources, as well as contributions from the eyes, and thus were likely VsEPs. These results show considerable promise as a new method for assessment of the central vestibular system by means of VsEPs produced by IA applied to the head.

  3. Cortical Auditory Disorders: A Case of Non-Verbal Disturbances Assessed with Event-Related Brain Potentials

    Directory of Open Access Journals (Sweden)

    Sönke Johannes

    1998-01-01

    Full Text Available In the auditory modality, there has been a considerable debate about some aspects of cortical disorders, especially about auditory forms of agnosia. Agnosia refers to an impaired comprehension of sensory information in the absence of deficits in primary sensory processes. In the non-verbal domain, sound agnosia and amusia have been reported but are frequently accompanied by language deficits whereas pure deficits are rare. Absolute pitch and musicians’ musical abilities have been associated with left hemispheric functions. We report the case of a right handed sound engineer with the absolute pitch who developed sound agnosia and amusia in the absence of verbal deficits after a right perisylvian stroke. His disabilities were assessed with the Seashore Test of Musical Functions, the tests of Wertheim and Botez (Wertheim and Botez, Brain 84, 1961, 19–30 and by event-related potentials (ERP recorded in a modified 'oddball paradigm’. Auditory ERP revealed a dissociation between the amplitudes of the P3a and P3b subcomponents with the P3b being reduced in amplitude while the P3a was undisturbed. This is interpreted as reflecting disturbances in target detection processes as indexed by the P3b. The findings that contradict some aspects of current knowledge about left/right hemispheric specialization in musical processing are discussed and related to the literature concerning cortical auditory disorders.

  4. Delineating the effects of anodal transcranial direct current stimulation on myoelectric control based on slow cortical potentials.

    Science.gov (United States)

    Dutta, Anirban; Boulenouar, Rahima S; Guiraud, David; Nitsche, Michael A

    2014-01-01

    Active cortical participation in rehabilitation procedures may be facilitated by modulating neuromuscular electrical stimulation (NMES) with electromyogram (EMG) and electroencephalogram (EEG) derived biopotentials, that represent simultaneous volitional effort. Here, the ability of the nervous system to respond to intrinsic or extrinsic stimuli by reorganizing its structure, function, and connections is called neuroplasticity. Neuroplasticity is involved in post-stroke functional disturbances, but also in rehabilitation. Beneficial neuroplastic changes may be facilitated with an adjuvant treatment with non-invasive brain stimulation (NIBS). This paper presents the results from a motor cortex anodal tDCS-EEG/EMG study in healthy volunteers. We investigated slow cortical potentials (SCP) during self-initiated movements. In this preliminary study, we found that anodal tDCS increased baseline-normalized post-tDCS mean power in the Theta band (4-8 Hz) of resting state EEG (60.71% vs. 8.36%; papplied to auto-correlated noise—in this case the output of a leaky stochastic accumulator—can account for the specific shape of the SCP prior to movement. We postulate that the anodal tDCS facilitated change in the slope of SCP may be related to the reaction times during a cued movement task since our prior work showed that anodal tDCS decreases the delay in initiation of muscle contraction and increases the delay in termination of muscle activity.

  5. Factors that influence Greeks' decision to register as potential bone marrow donors.

    Science.gov (United States)

    Galanis, P A; Sparos, L D; Katostaras, T; Velonakis, E; Kalokerinou, A

    2008-06-01

    Hemopoietic stem cells can be used from bone marrow or blood or umbilical cord blood of matched siblings or appropriately matched unrelated volunteers. Today, large bone marrow registries have been established to help identify volunteer unrelated bone marrow donors for patients lacking a family donor. Despite there being almost 10 million registered potential bone marrow donors (PBMD) worldwide, only 50% of white patients have a suitable bone marrow match. Growth in the number of PBMD increases the likelihood of finding a compatible donor for a patient. The attitudes and knowledge of 250 registered PBMD and 315 not registered PBMD toward bone marrow donation, tissues and organs donation, and blood donation were surveyed, using a questionnaire with 27 items. Multivariate logistic regression identified gender (females more often than males), regular blood donation, having a relative or a friend who has already been registered as PBMD, having a relative or a friend who needs bone marrow transplantation, family discussion about tissue and organ donation, knowledge about bone marrow transplantation, information about bone marrow transplantation, and trust in health professionals were independent predictive factors influencing people's decision to register as PBMD. Knowledge of these factors is important to target recruitment efforts.

  6. The effect of muscle contusion on cortical bone and muscle perfusion following reamed, intramedullary nailing: a novel canine tibia fracture model

    Directory of Open Access Journals (Sweden)

    Zdero Rad

    2010-11-01

    Full Text Available Abstract Background Management of tibial fractures associated with soft tissue injury remains controversial. Previous studies have assessed perfusion of the fractured tibia and surrounding soft tissues in the setting of a normal soft tissue envelope. The purpose of this study was to determine the effects of muscle contusion on blood flow to the tibial cortex and muscle during reamed, intramedullary nailing of a tibial fracture. Methods Eleven adult canines were distributed into two groups, Contusion or No-Contusion. The left tibia of each canine underwent segmental osteotomy followed by limited reaming and locked intramedullary nailing. Six of the 11 canines had the anterior muscle compartment contused in a standardized fashion. Laser doppler flowmetry was used to measure cortical bone and muscle perfusion during the index procedure and at 11 weeks post-operatively. Results Following a standardized contusion, muscle perfusion in the Contusion group was higher compared to the No-Contusion group at post-osteotomy and post-reaming (p 0.05. There was a sustained decrease in overall bone perfusion in the Contusion group at 11 weeks, compared to the No-Contusion group (p Conclusions Injury to the soft tissue envelope may have some deleterious effects on intraosseous circulation. This could have some influence on the fixation method for tibia fractures linked with significant soft tissue injury.

  7. Effect of accelerated electron beam on mechanical properties of human cortical bone: influence of different processing methods.

    Science.gov (United States)

    Kaminski, Artur; Grazka, Ewelina; Jastrzebska, Anna; Marowska, Joanna; Gut, Grzegorz; Wojciechowski, Artur; Uhrynowska-Tyszkiewicz, Izabela

    2012-08-01

    Accelerated electron beam (EB) irradiation has been a sufficient method used for sterilisation of human tissue grafts for many years in a number of tissue banks. Accelerated EB, in contrast to more often used gamma photons, is a form of ionizing radiation that is characterized by lower penetration, however it is more effective in producing ionisation and to reach the same level of sterility, the exposition time of irradiated product is shorter. There are several factors, including dose and temperature of irradiation, processing conditions, as well as source of irradiation that may influence mechanical properties of a bone graft. The purpose of this study was to evaluate the effect e-beam irradiation with doses of 25 or 35 kGy, performed on dry ice or at ambient temperature, on mechanical properties of non-defatted or defatted compact bone grafts. Left and right femurs from six male cadaveric donors, aged from 46 to 54 years, were transversely cut into slices of 10 mm height, parallel to the longitudinal axis of the bone. Compact bone rings were assigned to the eight experimental groups according to the different processing method (defatted or non-defatted), as well as e-beam irradiation dose (25 or 35 kGy) and temperature conditions of irradiation (ambient temperature or dry ice). Axial compression testing was performed with a material testing machine. Results obtained for elastic and plastic regions of stress-strain curves examined by univariate analysis are described. Based on multivariate analysis, including all groups, it was found that temperature of e-beam irradiation and defatting had no consistent significant effect on evaluated mechanical parameters of compact bone rings. In contrast, irradiation with both doses significantly decreased the ultimate strain and its derivative toughness, while not affecting the ultimate stress (bone strength). As no deterioration of mechanical properties was observed in the elastic region, the reduction of the energy

  8. Effect of ovariectomy on BMD, micro-architecture and biomechanics of cortical and cancellous bones in a sheep model.

    Science.gov (United States)

    Wu, Zi-xiang; Lei, Wei; Hu, Yun-yu; Wang, Hai-qiang; Wan, Shi-yong; Ma, Zhen-sheng; Sang, Hong-xun; Fu, Suo-chao; Han, Yi-sheng

    2008-11-01

    Osteoporotic/osteopenia fractures occur most frequently in trabeculae-rich skeletal sites. The purpose of this study was to use a high-resolution micro-computed tomography (micro-CT) and dual energy X-ray absorptionmeter (DEXA) to investigate the changes in micro-architecture and bone mineral density (BMD) in a sheep model resulted from ovariectomy (OVX). Biomechanical tests were performed to evaluate the strength of the trabecular bone. Twenty adult sheeps were randomly divided into three groups: sham group (n=8), group 1 (n=4) and group 2 (n=8). In groups 1 and 2, all sheep were ovariectomized (OVX); in the sham group, the ovaries were located and the oviducts were ligated. In all animals, BMD for lumbar spine was obtained during the surgical procedure. BMD at the spine, femoral neck and femoral condyle was determined 6 months (group 1) and 12 months (group 2) post-OVX. Lumbar spines and femora were obtained and underwent BMD scan, micro-CT analysis. Compressive mechanical properties were determined from biopsies of vertebral bodies and femoral condyles. BMD, micro-architectural parameters and mechanical properties of cancellous bone did not decrease significantly at 6 months post-OVX. Twelve months after OVX, BMD, micro-architectural parameters and mechanical properties decreased significantly. The results of linear regression analyses showed that trabecular thickness (Tb.Th) (r=0.945, R2=0.886) and bone volume fraction (BV/TV) (r=0.783, R2=0.586) had strong (R2>0.5) correlation to compression stress. In OVX sheep, changes in the structural parameters of trabecular bone are comparable to the human situation during osteoporosis was induced. The sheep model presented seems to meet the criteria for an osteopenia model for fracture treatment with respect to morphometric and mechanical properties. But the duration of OVX must be longer than 12 months to ensure the animal model can be established successfully.

  9. Anterior Reduction, Discectomy, and Three Cortical Iliac Bone Grafting With Instrumentation to Treat A Huge Tear Drop Fracture of the Axis: A Case Report and Literature Review.

    Science.gov (United States)

    Ma, Litai; Yang, Yi; Gong, Quan; Ding, Chen; Liu, Hao; Hong, Ying

    2016-04-01

    Fractures of the axis body have been little reported and treatment strategies remain controversial and individualized. Not more than 10 cases of huge tear drop fracture of the axis (HTDFA) have been reported in previous studies and the treatment method varies from conservative treatment to an anterior, or posterior, approach surgery. Considering the sparse knowledge of HTDFA, we present a special case report to share our experience and to explore the safety and effectiveness of anterior reduction and fusion to treat HTDFA. A 24-year-old man was referred to our department; he presented with neck pain lasting for 12 h since being involved in a roll-over motor vehicle accident. His neck movement was limited but there was no neurological compromise. Physical examination of the patient showed myodynamia of four limbs Grade 5, Hoffmann sign (-), and Babinski sign (-). Three-dimensional reconstruction computed tomography (CT) confirmed a huge tear drop fracture of the anterior-inferior corner of the axis and discontinuity of the cortex of the axis. After discussion with the spinal surgeon team in the department and an effective conversation with the patient, surgery involving anterior reduction, discectomy, and three cortical iliac bone grafts with instrumentation after transnasal induction of general anesthesia was performed. The patient was instructed to wear a cervical collar until he returned to our department for a follow-up examination some 3 months after surgery. The 3-month postoperative x-ray and CT scan showed a good position of the implant and bony fusion at the C2/3 segment. Anterior reduction, discectomy, and three cortical iliac bone grafts with instrumentation to treat HTDFA are effective, safe, and simple. Of course, longer follow-up duration and more cases are warranted to verify this procedure. Anterior reduction, discectomy, and bone grafting with instrumentation are warranted for most HTDFA cases. However, if HTDFA incorporates other complex

  10. Anterior Reduction, Discectomy, and Three Cortical Iliac Bone Grafting With Instrumentation to Treat A Huge Tear Drop Fracture of the Axis

    Science.gov (United States)

    Ma, Litai; Yang, Yi; Gong, Quan; Ding, Chen; Liu, Hao; Hong, Ying

    2016-01-01

    Abstract Fractures of the axis body have been little reported and treatment strategies remain controversial and individualized. Not more than 10 cases of huge tear drop fracture of the axis (HTDFA) have been reported in previous studies and the treatment method varies from conservative treatment to an anterior, or posterior, approach surgery. Considering the sparse knowledge of HTDFA, we present a special case report to share our experience and to explore the safety and effectiveness of anterior reduction and fusion to treat HTDFA. A 24-year-old man was referred to our department; he presented with neck pain lasting for 12 h since being involved in a roll-over motor vehicle accident. His neck movement was limited but there was no neurological compromise. Physical examination of the patient showed myodynamia of four limbs Grade 5, Hoffmann sign (–), and Babinski sign (–). Three-dimensional reconstruction computed tomography (CT) confirmed a huge tear drop fracture of the anterior–inferior corner of the axis and discontinuity of the cortex of the axis. After discussion with the spinal surgeon team in the department and an effective conversation with the patient, surgery involving anterior reduction, discectomy, and three cortical iliac bone grafts with instrumentation after transnasal induction of general anesthesia was performed. The patient was instructed to wear a cervical collar until he returned to our department for a follow-up examination some 3 months after surgery. The 3-month postoperative x-ray and CT scan showed a good position of the implant and bony fusion at the C2/3 segment. Anterior reduction, discectomy, and three cortical iliac bone grafts with instrumentation to treat HTDFA are effective, safe, and simple. Of course, longer follow-up duration and more cases are warranted to verify this procedure. Anterior reduction, discectomy, and bone grafting with instrumentation are warranted for most HTDFA cases. However, if HTDFA incorporates other

  11. Refinement of the $n-\\alpha$ and $p-\\alpha$ fish-bone potential

    CERN Document Server

    Smith, E; Papp, Z

    2012-01-01

    The fishbone potential of composite particles simulates the Pauli effect by nonlocal terms. We determine the $n-\\alpha$ and $p-\\alpha$ fish-bone potential by simultaneously fitting to the experimental phase shifts. We found that with a double Gaussian parametrization of the local potential can describe the $n-\\alpha$ and $p-\\alpha$ phase shifts for all partial waves.

  12. Evaluation of the relationship of mandibular cortical index and panoramic mandibular index with bone mineral density using panoramic radiography in postmenopausal women: A short study

    Directory of Open Access Journals (Sweden)

    Gargi Saran

    2015-01-01

    Full Text Available Introduction: The problems associated with age-related skeletal osteopenia have received attention since the human skeleton undergoes a continuous physiologic decrease in bone mass with advancing age. Bone status at various sites can be assessed using dual-energy X-ray absorptiometry (DXA or quantitative computed tomography. It would be useful to answer whether radiographic changes in the mandible indicate skeletal osteopenia. Aims and Objectives: The aim and objective of the study was to examine the mandibular cortical index (MCI and panoramic mandibular index (PMI on panoramic radiograph and to establish a relationship between the two indices (MCI and PMI with the bone mineral density (BMD in postmenopausal women. Materials and Methods: The study consisted of 15 postmenopausal women within the age group of 45-75 years. BMD was performed by DXA and measured at the lumbar spine and femoral neck and values were recorded. Panoramic radiographs of the same women were obtained for measuring MCI and PMI. There were two groups taken as C1 and C2 for determination of MCI and PMI. Results: The Pearson correlation analysis revealed a significant correlation between age and T-score (r = −0.59, P < 0.05, i.e., as age increased the T-score decreased. Comparing the T-score of two MCI groups, t-test revealed MCI was 69.1% lower in C2 as compared to C1. The value of P < 0.001 and t-test revealed significantly different and lowered (32.4% inferior cortex level in C2 as compared to C1 (t = 4.76, P < 0.001. Conclusion: Results suggest that in this study panoramic radiography could be a reliable tool in screening for BMD.

  13. Improving Recovery from Catastrophic Bone Injuries: An Animal Model for Assessing the Bone Reparative Potential of Progenitor Cell Therapy

    Science.gov (United States)

    2009-08-01

    Liu, Y. Strecker, S., Wang, L., Kronenberg , M., Kalajzic, I. and Rowe, D. Characterizing the Osteogenic Potential of Mesenchymal Stem Cells and...Their Immediate Cellular Derivatives. J. Bone. Min. Res. 24: Suppl 1, Abst SA0220, 2009. 3. Kronenberg , M., Harrison, J., Ravi, N., Shin, D. and Rowe, D...Abst SA0227, 2009. 4. Harrison, J., Kronenberg , M. and Rowe, D. Tracking Expression of a Smooth Muscle Alpha- Actin-Red Fluorescent Protein (SMAA-RFP

  14. Bone

    Science.gov (United States)

    Helmberger, Thomas K.; Hoffmann, Ralf-Thorsten

    The typical clinical signs in bone tumours are pain, destruction and destabilization, immobilization, neurologic deficits, and finally functional impairment. Primary malignant bone tumours are a rare entity, accounting for about 0.2% of all malignancies. Also benign primary bone tumours are in total rare and mostly asymptomatic. The most common symptomatic benign bone tumour is osteoid osteoma with an incidence of 1:2000.

  15. Minerals and vitamins in bone health: the potential value of dietary enhancement.

    Science.gov (United States)

    Bonjour, Jean-Philippe; Guéguen, Léon; Palacios, Cristina; Shearer, Martin J; Weaver, Connie M

    2009-06-01

    Nutrition is important to bone health, and a number of minerals and vitamins have been identified as playing a potential role in the prevention of bone diseases, particularly osteoporosis. Despite this, there is currently no consensus on maximum levels to allow in food or as dietary supplements. The benefits of supplementation of populations at risk of osteoporosis with Ca and vitamin D are well established. Prolonged supplementation of Ca and vitamin D in elderly has been shown to prevent bone loss, and in some intervention studies to prevent fragility fractures. Although P is essential to bone health, the average intake is considered to be more than sufficient and supplementation could raise intake to adverse levels. The role of vitamin K in bone health is less well defined, though it may enhance the actions of Ca and vitamin D. Sr administered in pharmacological doses as the ranelate salt was shown to prevent fragility fractures in postmenopausal osteoporosis. However, there is no hard evidence that supplementation with Sr salts would be beneficial in the general population. Mg is a nutrient implicated in bone quality, but the benefit of supplementation via foodstuffs remains to be established. A consensus on dietary supplementation for bone health should balance the risks, for example, exposure of vulnerable populations to values close to maximal tolerated doses, against evidence for benefits from randomised clinical trials, such as those for Ca and vitamin D. Feedback from community studies should direct further investigations and help formulate a consensus on dietary supplementation for bone health.

  16. Potential of targeted drug delivery system for the treatment of bone metastasis.

    Science.gov (United States)

    Vinay, Raichur; KusumDevi, V

    2016-01-01

    Bone metastasis is a devastating complication of cancer that requires an immediate attention. Although our understanding of the metastatic process has improved over the years, yet a number of questions still remain unanswered, and more research is required for complete understanding of the skeletal consequences of metastasis. Furthermore, as no effective treatments are available for some of the most common skeleton disorders such as arthritis, osteoarthritis, osteosarcoma and metastatic bone cancer, there is an urgent need to develop new drugs and drug delivery systems for safe and efficient clinical treatments. Hence this article describes the potential of targeted delivery platforms aimed specifically at bone metastasized tumors. The review gives a brief understanding of the proposed mechanisms of metastasis and focuses primarily on the targeting moieties such as bisphosphonates, which represent the current gold standard in bone metastasis therapies. Special focus has been given to the targeted nanoparticulate systems for treating bone metastasis and its future. Also highlighted are some of the therapeutic targets that can be exploited for designing therapies for bone metastasis. Some of the patented molecules for bone metastasis prevention and treatment have also been discussed. Recently proposed HIFU-CHEM, which utilizes High Intensity Focused ultrasound (HIFU) guided by MRI in combination with temperature-sensitive nanomedicines has also been briefed. The study has been concluded with a focus on the innovations requiring an immediate attention that could improve the treatment modality of bone metastasis.

  17. Heating or freezing bone. Effects on angiogenesis induction and growth potential in mice.

    Science.gov (United States)

    Leunig, M; Yuan, F; Berk, D A; Gerweck, L E; Jain, R K

    1996-08-01

    We have characterized the effect of bone graft treatment by heating or freezing (with or without dimethyl sulfoxide (DMSO)). Tissue culture and dorsal skin-fold chambers in mice were used as sites to quantify the effect on angiogenesis, growth and calcification of neonatal femora. Fresh femora increased in both length and cartilage diameter (calcification in vivo only), but cryopreservation or heating abolished the increase in femoral dimensions. In vivo, femora of all experimental groups elicited an angiogenic response from the host tissue, which was most pronounced for fresh femora, weaker for DMSO-preserved frozen bone and poor for unprotected frozen bone and boiled femora. Freezing in the presence of a cryopreservative (DMSO) was found to preserve the angiogenic potential of frozen bone, whereas unprotected heating or freezing significantly impaired angiogenesis induction and growth potential.

  18. Potentiation of N-methyl-D-aspartate-induced currents by the nootropic drug nefiracetam in rat cortical neurons.

    Science.gov (United States)

    Moriguchi, Shigeki; Marszalec, William; Zhao, Xilong; Yeh, Jay Z; Narahashi, Toshio

    2003-10-01

    Nefiracetam is a new pyrrolidone nootropic drug being developed for the treatment of Alzheimer's type and post-stroke vascular-type dementia. In the brain of Alzheimer's disease patients, down-regulation of both cholinergic and glutamatergic systems has been found and is thought to play an important role in impairment of cognition, learning and memory. We have previously shown that the activity of neuronal nicotinic acetylcholine receptors is potently augmented by nefiracetam. The present study was undertaken to elucidate the mechanism of action of nefiracetam on glutamatergic receptors. Currents were recorded from rat cortical neurons in long-term primary culture using the whole-cell patch-clamp technique at a holding potential of -70 mV in Mg2+-free solutions. N-Methyl-D-aspartate (NMDA)-evoked currents were greatly and reversibly potentiated by bath application of nefiracetam resulting in a bell-shaped dose-response curve. The minimum effective nefiracetam concentration was 1 nM, and the maximum potentiation to 170% of the control was produced at 10 nM. Nefiracetam potentiation occurred at high NMDA concentrations that evoked the saturated response, and in a manner independent of NMDA concentrations ranging from 3 to 1,000 microM. Glycine at 3 microM potentiated NMDA currents but this effect was attenuated with an increasing concentration of nefiracetam from 1 to 10,000 nM. 7-Chlorokynurenic acid at 1 microM prevented nefiracetam from potentiating NMDA currents. Nefiracetam at 10 nM shifted the dose-response relationship for the 7-chlorokynurenic acid inhibition of NMDA currents in the direction of higher concentrations. Alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid- and kainate-induced currents were not significantly affected by application of 10 nM nefiracetam. It was concluded that nefiracetam potentiated NMDA currents through interactions with the glycine binding site of the NMDA receptor.

  19. Detection of the onset of upper-limb movements based on the combined analysis of changes in the sensorimotor rhythms and slow cortical potentials

    Science.gov (United States)

    Ibáñez, J.; Serrano, J. I.; del Castillo, M. D.; Monge-Pereira, E.; Molina-Rueda, F.; Alguacil-Diego, I.; Pons, J. L.

    2014-10-01

    Objective. Characterizing the intention to move by means of electroencephalographic activity can be used in rehabilitation protocols with patients’ cortical activity taking an active role during the intervention. In such applications, the reliability of the intention estimation is critical both in terms of specificity ‘number of misclassifications’ and temporal accuracy. Here, a detector of the onset of voluntary upper-limb reaching movements based on the cortical rhythms and the slow cortical potentials is proposed. The improvement in detections due to the combination of these two cortical patterns is also studied. Approach. Upper-limb movements and cortical activity were recorded in healthy subjects and stroke patients performing self-paced reaching movements. A logistic regression combined the output of two classifiers: (i) a naïve Bayes classifier trained to detect the event-related desynchronization preceding the movement onset and (ii) a matched filter detecting the bereitschaftspotential. The proposed detector was compared with the detectors by using each one of these cortical patterns separately. In addition, differences between the patients and healthy subjects were analysed. Main results. On average, 74.5 ± 13.8% and 82.2 ± 10.4% of the movements were detected with 1.32 ± 0.87 and 1.50 ± 1.09 false detections generated per minute in the healthy subjects and the patients, respectively. A significantly better performance was achieved by the combined detector (as compared to the detectors of the two cortical patterns separately) in terms of true detections (p = 0.099) and false positives (p = 0.0083). Significance. A rationale is provided for combining information from cortical rhythms and slow cortical potentials to detect the onsets of voluntary upper-limb movements. It is demonstrated that the two cortical processes supply complementary information that can be summed up to boost the performance of the detector. Successful results have been also

  20. Functional signature of recovering cortex: dissociation of local field potentials and spiking activity in somatosensory cortices of spinal cord injured monkeys.

    Science.gov (United States)

    Wang, Zheng; Qi, Hui-Xin; Kaas, Jon H; Roe, Anna W; Chen, Li Min

    2013-11-01

    After disruption of dorsal column afferents at high cervical spinal levels in adult monkeys, somatosensory cortical neurons recover responsiveness to tactile stimulation of the hand; this reactivation correlates with a recovery of hand use. However, it is not known if all neuronal response properties recover, and whether different cortical areas recover in a similar manner. To address this, we recorded neuronal activity in cortical area 3b and S2 in adult squirrel monkeys weeks after unilateral lesion of the dorsal columns. We found that in response to vibrotactile stimulation, local field potentials remained robust at all frequency ranges. However, neuronal spiking activity failed to follow at high frequencies (≥15 Hz). We suggest that the failure to generate spiking activity at high stimulus frequency reflects a changed balance of inhibition and excitation in both area 3b and S2, and that this mismatch in spiking and local field potential is a signature of an early phase of recovering cortex (

  1. Predictive value of neurological examination for early cortical responses to somatosensory evoked potentials in patients with postanoxic coma.

    Science.gov (United States)

    Bouwes, Aline; Binnekade, Jan M; Verbaan, Bart W; Zandbergen, Eveline G J; Koelman, Johannes H T M; Weinstein, Henry C; Hijdra, Albert; Horn, Janneke

    2012-03-01

    Bilateral absence of cortical N20 responses of median nerve somatosensory evoked potentials (SEP) predicts poor neurological outcome in postanoxic coma after cardiopulmonary resuscitation (CPR). Although SEP is easy to perform and available in most hospitals, it is worthwhile to know how neurological signs are associated with SEP results. The aim of this study was to investigate whether specific clinical neurological signs are associated with either an absent or a present median nerve SEP in patients after CPR. Data from the previously published multicenter prospective cohort study PROPAC (prognosis in postanoxic coma, 2000-2003) were used. Neurological examination, consisting of Glasgow Coma Score (GCS) and brain stem reflexes, and SEP were performed 24, 48, and 72 h after CPR. Positive predictive values for predicting absent and present SEP, as well as diagnostic accuracy were calculated. Data of 407 patients were included. Of the 781 SEPs performed, N20 s were present in 401, bilaterally absent in 299, and 81 SEPs were technically undeterminable. The highest positive predictive values (0.63-0.91) for an absent SEP were found for absent pupillary light responses. The highest positive predictive values (0.71-0.83) for a present SEP were found for motor scores of withdrawal to painful stimuli or better. Multivariate analyses showed a fair diagnostic accuracy (0.78) for neurological examination in predicting an absent or present SEP at 48 or 72 h after CPR. This study shows that neurological examination cannot reliably predict absent or present cortical N20 responses in median nerve SEPs in patients after CPR.

  2. Sensitivity of cortical auditory evoked potential detection for hearing-impaired infants in response to short speech sounds

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    Bram Van Dun

    2012-01-01

    Full Text Available

    Background: Cortical auditory evoked potentials (CAEPs are an emerging tool for hearing aid fitting evaluation in young children who cannot provide reliable behavioral feedback. It is therefore useful to determine the relationship between the sensation level of speech sounds and the detection sensitivity of CAEPs.

    Design and methods: Twenty-five sensorineurally hearing impaired infants with an age range of 8 to 30 months were tested once, 18 aided and 7 unaided. First, behavioral thresholds of speech stimuli /m/, /g/, and /t/ were determined using visual reinforcement orientation audiometry (VROA. Afterwards, the same speech stimuli were presented at 55, 65, and 75 dB SPL, and CAEP recordings were made. An automatic statistical detection paradigm was used for CAEP detection.

    Results: For sensation levels above 0, 10, and 20 dB respectively, detection sensitivities were equal to 72 ± 10, 75 ± 10, and 78 ± 12%. In 79% of the cases, automatic detection p-values became smaller when the sensation level was increased by 10 dB.

    Conclusions: The results of this study suggest that the presence or absence of CAEPs can provide some indication of the audibility of a speech sound for infants with sensorineural hearing loss. The detection of a CAEP provides confidence, to a degree commensurate with the detection probability, that the infant is detecting that sound at the level presented. When testing infants where the audibility of speech sounds has not been established behaviorally, the lack of a cortical response indicates the possibility, but by no means a certainty, that the sensation level is 10 dB or less.

  3. [Therapeutic potential of bone marrow stem cells in cerebral infarction].

    Science.gov (United States)

    Sánchez-Cruz, Gilberto; Milián-Rodríguez, Lismary

    2015-05-16

    Introduccion. Las celulas madre constituyen una alternativa terapeutica que se encuentra en fase de experimentacion para el infarto cerebral. Objetivo. Mostrar la evidencia cientifica existente sobre el potencial terapeutico de las celulas madre de la medula osea en esta enfermedad. Desarrollo. El infarto cerebral representa el 80% de las enfermedades cerebrovasculares. La trombolisis constituye la unica terapia aprobada, pero, por su estrecha ventana terapeutica, solo se aplica a un bajo porcentaje de los pacientes. De manera alternativa, los tratamientos neurorrestauradores, como el de celulas madre, pueden aplicarse en periodos mas prolongados. Por esta razon se efectuo una busqueda bibliografica en PubMed con el empleo de las palabras clave 'stem cells', 'bone marrow derived mononuclear cells' y 'stroke'. Se encontraron evidencias de seguridad y eficacia de dichas celulas en diferentes momentos evolutivos del infarto cerebral. Se identificaron estudios que en clinica y preclinica las recolectaron por puncion medular y en sangre periferica, y las trasplantaron directamente en el area infartada o por via intravascular. El efecto terapeutico se relaciona con sus propiedades de plasticidad celular y liberacion de factores troficos. Conclusiones. El concentrado de celulas mononucleares autologas, obtenido en sangre periferica o por puncion de la medula osea, y trasplantado por via intravenosa, es una factible opcion metodologica que permitira rapidamente incrementar el numero de ensayos clinicos en diferentes etapas evolutivas del infarto cerebral. Esta terapia muestra seguridad y eficacia; sin embargo, deben ampliarse las evidencias que avalen su generalizacion en humanos.

  4. Cortical Reorganization in Dyslexic Children after Phonological Training: Evidence from Early Evoked Potentials

    Science.gov (United States)

    Spironelli, Chiara; Penolazzi, Barbara; Vio, Claudio; Angrilli, Alessandro

    2010-01-01

    Brain plasticity was investigated in 14 Italian children affected by developmental dyslexia after 6 months of phonological training. The means used to measure language reorganization was the recognition potential, an early wave, also called N150, elicited by automatic word recognition. This component peaks over the left temporo-occipital cortex…

  5. Osteogenic potential of the human bone morphogenetic protein 2 gene activated nanobone putty

    Institute of Scientific and Technical Information of China (English)

    TIAN Xiao-bin; SUN Li; YANG Shu-hua; ZHANG Yu-kun; HU Ru-yin; FU De-hao

    2008-01-01

    Background Nanobone putty is an injectable and bioresorbable bone substitute. The neutral-pH putty resembles hard bone tissue, does not contain polymers or plasticizers, and is self-setting and nearly isothermic, properties which are helpful for the adhesion, proliferation, and function of bone cells. The aim of this study was to investigate the osteogenic potential of human bone morphogenetic protein 2(hBMP2)gene activated nanobone putty in inducing ectopic bone formation, and the effects of the hBMP2 gene activated nanobone putry on repairing bone defects. Methods Twenty four Kunming mice were randomly divided into two groups. The nanobone putty+hBMP2 plasmid was injected into the right thigh muscle pouches of the mice(experiment side). The nanobone putty+blank plasmid or nanobone putty was injected into the left thigh muscle pouches of the group 1(control side 1)or group 2(control side 2), respectively. The effects of ectopic bone formation were evaluated by radiography, histology, and molecular biology analysis at 2 and 4 weeks after operation. Bilateral 15 mm radial defects were made in forty-eight rabbits. These rabbits were randomly divided into three groups: Group A, nanobone putty+hBMP2 plasmid;Group B, putty+blank plasmid; Group C, nanobone putty only. Six rabbits with left radial defects served as blank controls. The effect of bone repairing was evaluated by radiography, histology, molecular biology, and biomechanical analysis at 4, 8, and 12 weeks after operation. Results The tissue from the experimental side of the mice expressed hBMP2. Obvious cartilage and island-distributed immature bone formation in implants of the experiment side were observed at 2 weeks after operation, and massive mature bone observed at 4 weeks. No bone formation was observed in the control side of the mice. The ALP activity in the experiment side of the mice was higher than that in the control side. The tissue of Group A rabbits expressed hBMP2 protein and higher ALP level

  6. Comparação da resistência à tração da âncora metálica rosqueada inserida no osso cortical e no osso esponjoso Comparison of the tensile strength of threaded metal anchors inserted on cortical and spongy bones

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