Association of physical exercise and calcium intake with bone mass measured by quantitative ultrasound

<p>Abstract</p> <p>Background</p> <p>Interventions other than medications in the management of osteoporosis are often overlooked. The purpose of this study was to investigate the association of physical activity and calcium intake with bone parameters.</p> <p>Methods</p> <p>We measured the heel T-score and stiffness index (SI) in 1890 pre- and postmenopausal women by quantitative ultrasound (QUS) and assessed physical activity and dietary calcium intake by questionnaire. Participants were divided according to their weekly physical activity (sedentary, moderately active, systematically active) and daily calcium consumption (greater than or less than 800 mg/day).</p> <p>Results</p> <p>SI values were significantly different among premenopausal groups (p = 0.016) and between sedentary and systematically active postmenopausal women (p = 0.039). QUS T-scores in systematically active premenopausal women with daily calcium intake > 800 mg/day were significantly higher than those in all other activity groups (p < 0.05) independent of calcium consumption.</p> <p>Conclusions</p> <p>Systematic physical activity and adequate dietary calcium intake are indicated for women as a means to maximize bone status benefits.</p

Explicit expressions for the estimation of the elastic constants of lamellar bone as a function of the volumetric mineral content using a multi-scale approach

[EN] In this work, explicit expressions to estimate all the transversely isotropic elastic constants of lamellar bone as a function of the volumetric bone mineral density (BMD) are provided. The methodology presented is based on the direct homogenization procedure using the finite element method, the continuum approach based on the Hill bounds, the least-square method and the mean field technique. Firstly, a detailed description of the volumetric content of the different components of bone is provided. The parameters defined in this step are related to the volumetric BMD considering that bone mineralization process occurs at the smallest scale length of the bone tissue. Then, a thorough description provides the details of the numerical models and the assumptions adopted to estimate the elastic behaviour of the forward scale lengths. The results highlight the noticeable influence of the BMD on the elastic modulus of lamellar bone. Power law regressions fit the Young's moduli, shear stiffness moduli and Poisson ratios. In addition, the explicit expressions obtained are applied to the estimation of the elastic constants of cortical bone. At this scale length, a representative unit cell of cortical bone is analysed including the fibril orientation pattern given by Wagermaier et al. (Biointerphases 1:1-5, 2006) and the BMD distributions observed by Granke et al. (PLoS One 8:e58043, 2012) for the osteon. Results confirm that fibril orientation arrangement governs the anisotropic behaviour of cortical bone instead of the BMD distribution. The novel explicit expressions obtained in this work can be used for improving the accuracy of bone fracture risk assessment.The authors acknowledge the Ministerio de Economia y Competitividad for the financial support received through the project DPI2013-46641-R and to the Generalitat Valenciana for Programme PROMETEO 2016/007. The authors declare that they have no conflict of interestVercher Martínez, A.; Giner Maravilla, E.; Belda, R.; Aigoun, A.; Fuenmayor Fernández, F. (2018). Explicit expressions for the estimation of the elastic constants of lamellar bone as a function of the volumetric mineral content using a multi-scale approach. Biomechanics and Modeling in Mechanobiology. 17(2):449-464. https://doi.org/10.1007/s10237-017-0971-xS449464172Akiva U, Wagner HD, Weiner S (1998) Modelling the three-dimensional elastic constants of parallel-fibred and lamellar bone. J Mater Sci 33:1497–1509Ascenzi A, Bonucci E (1967) The tensile properties of single osteons. Ana Rec 158:375–386Barbour KE, Zmuda JM, Strotmeyer ES, Horwitz MJ, Boudreau R, Evans RW, Ensrud K, Petit MA, Gordon CL, Cauley JA (2013) Correlates of trabecular and cortical volumetric bone mineral density of the radius and tibia older men: the osteoporotic fractures in men study. J Bone Miner Res 25(5):1017–1028Bar-On B, Wagner HD (2013) Structural motifs and elastic properties of hierarchical biological tissues—a review. J Struct Biol 183:149–164Cowin SC (2000) How is a tissue built? J Biomech Eng 122:553–569Cowin SC (2001) Bone mechanics handbook, 2nd edn. CRC Press, Boca RatonCurrey JD (1986) Power law models for the mechanical properties of cancellous bone. Eng Med 15(3):153–154Currey JD (1988) The effect of porosity and mineral content on the Young’s modulus of elasticity of compact bone. J Biomech 21:131–139Daszkiewicz K, Maquer G, Zysset PK (2017) The effective elastic properties of human trabecular bone may be approximated using micro-finite element analyses of embedded volume elements. Biomech Model Mechanobiol 16:731–742Faingold A, Sidney RC, Wagner HD (2012) Nanoindentation of osteonal bone lamellae. J Mech Biomech Materials 9:198–206Fratzl P, Fratzl-Zelman N, Klaushofer K, Vogl G, Koller K (1991) Nucleation and growth of mineral crystals in bone studied by small-angle X-ray scattering. Calcif Tissue Int 48:407–413Fritsch A, Hellmich C (2007) ’Universal’ microstructural patterns in cortical and trabecular, extracellular and extravascular bone materials: micromechanics-based prediction of anisotropic elasticity. J Theo Biol 24:597–620Grampp S, Genant HK, Mathur A, Lang P, Jergas M, Takada M, Glüer CC, Lu Y, Chavez M (1997) Comparisons of noninvasive bone mineral measurements in assessing age-related loss, fracture discrimination and diagnostic classification. J Bone Miner Res 12:697–711Grant CA, Langton C, Schuetz MA, Epari DR (2011) Determination of the material properties of ovine cortical bone. Poster No. 2226, 57th Orthopaedic Research Society (ORS) Annual meeting, Long Beach, CaliforniaGranke M, Gourrier A, Rupin F, Raum K, Peyrin F, Burghammer M, Saïd A, Laugier P (2012) Microfibril orientation dominates the microelastic properties of human bone tissue at the lamellar length scale. PLoS One 8:e58043Gurtin ME (1972) The linear theory of elasticity. Handbuch del Physik VIa 2:1–296Hamed E, Jasiuk I (2012) Elastic modeling of bone at nanostructural level. Mat Sci Eng R73:27–49Hernández CJ, Beaupré GS, Keller TS, Carter DR (2001a) The influence of bone volume fraction and ash fraction on bone strength and modulus. Bone 29:74–78Hill R (1952) The elastic behaviour of a crystalline aggregate. Proc Phys Soc Sec A 65:349–354Hodge AJ, Petruska JA (1963) Recent studies with the electron microscope on ordered aggregates of the tropocollagen macromolecule. In: Ramachandran GN (ed) Aspects of protein structure. Academic Press, New York, pp 289–300Jäger I, Fratzl P (2000) Mineralized collagen: a mechanical model with a staggered arrangement of mineral particles. Biophys J 78:1737–1746Kuhn JL, Goldstein SA, Choi K, London M, Feldkamp LA, Matthews LS (1989) Comparison of the trabecular and cortical tissue moduli from human iliac crests. J Orthop Res 7:876–884Landis WJ, Song MJ, Leith A, McEwen L, McEwen BF (1993) Mineral and organic matrix interaction in normally calcifying tendon visualized in three dimensions by high-voltage electron microscopic tomography and graphic image reconstruction. J Struct Biol 110:39–54Lees S, Heeley JD, Cleary PF (1979) A study of some properties of a sample of bovine cortical bone using ultrasound. Calcif Tissue Int 29:107–117Lekhnitskii SG (1963) Theory of elasticity of anisotropic elastic body. Holden-Day, San Francisco, pp 1–73Lempriere BM (1968) Poisson’s ratio in orthotropic materials. Am Inst Aeronaut Astronaut J J6:2226–2227Liu Y, Kim YK, Dai L, Li N, Khan SO, Pashley DH, Tay FR (2011) Hierarchical and non-hierarchical mineralization of collagen. Biomater 32:1291–1300Majumdar S, Kothari M, Augat P, Newitt DC, Link TM, Lin JC, Lang T, Lu Y, Genant HK (1998) High-resolution magnetic resonance imaging: three-dimensional trabecular bone architecture and biomechanical properties. Bone 22(5):445–454Martínez-Reina J, Domínguez J, García-Aznar JM (2011) Effect of porosity and mineral content on the elastic constants of cortical bone: a multiscale approach. Biomech Model Mechanobiol 10:309–322Nobakhti S, Limbert G, Thurner PJ (2014) Cement lines and interlamellar areas in compact bone as strain amplifiers—Contributors to elasticity, fracture toughness and mechanotransduction. J Mech Behav Biomed Mater 29:235–251Orgel JPRO, Irving TC, Miller A, Wess TJ (2006) Microfibrillar structure of type I collagen in situ. PNAS USA 103:9001–9005Reisinger AG, Pahr DH, Zysset PK (2010) Sensitivity analysis and parametric study of elastic properties of unidirectional mineralized bone fibril-array using mean field methods. Biomech Model Mechanobiol 9:499–510Reisinger AG, Pahr DH, Zysset PK (2011) Elastic anisotropy of bone lamellae as a function of fibril orientation pattern. Biomech Model Mechanobiol 10:67–77Rho JY, Kuhn-Spearing L, Zioupos P (1998) Mechanical properties and the hierarchical structure of bone. Med Eng Phys 20:92–102Robinson RA, Rochester MD (1952) An electron-microscopic study of the crystalline inorganic component of bone and its relationship to the organic matrix. J Bone Joint Surg 34–a:389–435Roque WL, Arcaro K, Alberich-Bayarri A (2013) Mechanical competence of bone: a new parameter to grade trabecular bone fragility from tortuosity and elasticity. IEEE Trans Bio Eng 60:1363–1370Rubin MA, Jasiuk I, Taylor J, Rubin J, Ganey T, Apkarian RP (2003) TEM analysis of the nanostructure of normal and osteoporotic human trabecular bone. Bone 33:270–282Sasaki N, Tagami A, Goto T, Taniguchi M, Nakata M, Hikichi K (2002) Atomic force microscopic studies on the structure of bovine femoral cortical bone at the collagen fibril-mineral level. J Mater Sci Mater Med 13(3):333–337Schaffler MB, Burr DB (1988) Stiffness of compact bone: effects of porosity and density. J Biomech 21:13–16Silver FH, Landis WJ (2011) Deposition of apatite in mineralizing vertebrate extracellular matrices: a model of possible nucleation sites on type I collagen. Connect Tissue Res 52:242–254Tommasini SM, Nasser P, Hu B, Jepsen KJ (2008) Biological co-adaptation of morphological and composition traits contributes to mechanical functionality and skeletal fragility. J Bone Miner Res 23:236–246Ulrich D, Rietbergen B, Weinans H, Rüegsegger P (1998) Finite element analysis of trabecular bone structure: a comparison of image-based meshing techniques. J Biomech 31:1187–1192Ulrich D, Rietbergen B, Laib A, Rüegsegger P (1999) The ability of three-dimensional structural indices to reflect mechanical aspects of trabecular bone. Bone 25:55–60Vercher A, Giner E, Arango C, Tarancón JE, Fuenmayor FJ (2014) Homogenized stiffness matrices for mineralized collagen fibrils and lamellar bone using unit cell finite element models. Biomech Model Mechanobiol 13:437–449Vercher-Martínez A, Giner E, Arango C, Fuenmayor FJ (2015) Influence of the mineral staggering on the elastic properties of the mineralized collagen fibril in lamellar bone. J Mech Behav Biomed Mater 42:243–256Wagermaier W, Gupta HS, Gourrier A, Burghammer M, Roschger P, Fratzl P (2006) Spiral twisting of fiber orientation inside bone lamellae. Biointerphases 1:1–5Weiner S, Traub W (1986) Organization of hydroxiapatite within collagen fibrils. FEBS Lett 206:262–266Weiner S, Wagner HD (1998) The material bone: structure-mechanical function relations. Annu Rev Mater Sci 28:271–298Yang L, Palermo L, Black DM, Eastell R (2014) Prediction of incident hip fracture with the estimated femoral strength by finite element analysis of DXA scans in the study of osteoporotic fractures. JBMR 29:2594–2600Yuan YJ, Cowin SC (2008a) The estimated elastic constants for a single bone osteonal lamella. Biomech Model Mechanobiol 7:1–11Yu W, Glüer CC, Grampp S, Jergas M, Fuerst T, Wu CY, Lu Y, Fan B, Genant HK (1995) Spinal bone mineral assessment in postmenopausal women: a comparison between dual X-ray absorptiometry and quantitative computed tomography. Osteoporos Int 5:433–439Yang L, Palermo L, Black DM, Eastell R (2014) Prediction of incident hip fracture with the estimated femoral strength by finite element analysis of DXS Scans in the study of osteoporotic fractures. J Bone Miner Res 29(12):2594–2600Yuan F, Stock SR, Haeffner DR, Almer JD, Dunand DC, Brinson LC (2011) A new model to simulate the elastic properties of mineralized collagen fibril. Biomech Model Mechanobiol 10:147–16

Screening for low bone mass with quantitative ultrasonography in a community without dual-energy X-ray absorptiometry: population-based survey

BACKGROUND: Dual-energy x-ray absorptiometry (DXA) is the criterion standard to identify low bone mineral density (BMD), but access to axial DXA may be limited or cost prohibitive. We screened for low bone mass with quantitative ultrasonography (QUS) in a community without DXA, analyzed its reliability and obtained reference values and estimated the prevalence of low QUS values. METHODS: We enrolled 6493 residents of Kinmen, Taiwan, and a reference group (96 men and 70 women aged 20–29 years) for this cross-sectional, community-based study. All participants completed a questionnaire and underwent ultrasonographic measurements. Reliability and validity of QUS measurements were evaluated. Broadband ultrasound attenuation (BUA) values were obtained and statistically analyzed by age, sex and weight. Annual loss of BUA was determined. Trends in the prevalence of QUS scores were evaluated. RESULTS: Two QUS were used and had a correlation coefficient of 0.90 (p < 0.001). Calcaneal BUA was significantly correlated with BMD in the femoral neck (r = 0.67, p < 0.001) and BMD of the total lumbar spine (r = 0.59, p < 0.001). BUAs in the reference group were 92.72 ± 13.36 and 87.90 ± 10.68 dB/MHz for men and women, respectively. Estimated annual losses of calcaneal BUA were 0.83% per year for women, 0.27% per year for men, and 0.51% per year for the total population. The prevalence of severely low QUS values (T-score = -2.5) tended to increase with aging in both sexes (p < 0.001). Across age strata, moderately low QUS values (-2.5 < T-score < -1.0) were 31.6–41.0% in men and 23.7–38.1% in women; a significant trend with age was observed in men (p < 0.001). CONCLUSION: Age-related decreases in calcaneal ultrasonometry, which reflected the prevalence of low bone mass, were more obvious in women than in men

Secure synthesis and activation of protocol translation agents

Protocol heterogeneity is pervasive and is a major obstacle to effective integration of services in large systems. However, standardization is not a complete answer. Standardized protocols must be general to prevent a proliferation of standards, and can therefore become complex and inefficient. Specialized protocols can be simple and efficient, since they can ignore situations that are precluded by application characteristics. One solution is to maintain agents for translating between protocols. However, n protocol types would require agents, since an agent must exist for a source - destination pair. A better solution is to create agents as needed. This paper examines the issues in the creation and management of protocol translation agents. We focus on the design of Nestor, an environment for synthesizing and managing RPC protocol translation agents. We provide rationale for the translation mechanism and the synthesis environment, with specific emphasis on the security issues arising in Nestor. Nestor has been implemented and manages heterogeneous RPC agents generated using the Cicero protocol construction language and the URPC toolkit.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/49229/2/ds7402.pd

Properties of electrolyte-filled glass microelectrodes : a model analysis

A novel dynamic mathematical microelectrode model (a model of solvent and solute kinetics in electrolyte-filled microelectrodes) was deduced from experimental observations made on standard (single-barrelled, 3.0 M KCl-filled, approximately 10 M[ohm]) electrodes using (a) electrodiffusion, electro-osmosis, and continuity equations that were placed into the constraints of electrode geometry, and (b) handbook/textbook parameter values, only. The model proved to be able to faithfully reproduce all observed electrochemical and electrical electrode properties, i.e. even those that constituted no part of the model's experimental basis. In theoretical tests, the model shows, for the standard electrode that (a) inside the electrode, any profiles in electrical potential and electrolyte concentration are occurring at the most distal part (approximately 50 microm) of the tip region, (b) asymmetrical shifts in electrolyte concentration just inside the electrode tip opening are the true cause of the electrode's current rectification, and (c) strong transelectrode currents are producing water flows across the electrode orifice that may affect the volume of smaller and medium-sized cells. In further tests, the model shows, among other things, for non-standard electrodes that (a) decreasing the electrode electrolyte concentration will give rise to marked decreases in electrolyte leakage from the electrode, but only very minor changes in tip potential, and (b) increasing the surface charge of the electrode glass (increases in zeta potential) and/or decreasing the electrode electrolyte concentration will produce increases in electro-osmotic water transport, which may be desirable for the intracellular injection of water-soluble (electro-neutral) substances