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61.
The control mechanism of mechanical bone remodeling at cellular level was investigated by means of an extensive parametric study on a theoretical model described in this paper. From a perspective of control mechanism, it was found that there are several control mechanisms working simultaneously in bone remodeling which is a complex process. Typically, an extensive parametric study was carried out for investigating model parameter space related to cell differentiation and apoptosis which can describe the fundamental cell lineage behaviors. After analyzing all the combinations of 728 permutations in six model parameters, we have identified a small number of parameter combinations that can lead to physiologically realistic responses which are similar to theoretically idealized physiological responses. The results presented in the work enhanced our understanding on mechanical bone remodeling and the identified control mechanisms can help researchers to develop combined pharmacological-mechanical therapies to treat bone loss diseases such as osteoporosis. 相似文献
62.
Virginia P. Silva Nykänen Mervi A. Puska Antti Nykänen Janne Ruokolainen 《Journal of Polymer Science.Polymer Physics》2013,51(17):1318-1327
This work presents the synthesis of polyphosphazenes bearing L ‐proline methyl ester (ProOMe) and 4‐hydroxy‐l ‐proline methyl ester (HypOMe), aiming for new bioactive polymers for bone repair. The polymers were characterized by 1H and 31P NMR, FTIR, DSC, and TGA. Electrospun fibers were prepared using poly[bis(l ‐proline methyl ester)phosphazene] (PProP), and their potential for biomimetic mineralization, as well as the bulk material, were tested in simulated body fluid (1×SBF). Samples were analyzed between 24 h and 3 weeks of incubation using SEM/EDS and FTIR. After 24 h, spherical and flower‐like shapes of calcium phosphates (CaP) were crystallized on the bulk samples. The nanofibers presented spherical CaP crystals attached to them after 48 h of incubation. The Ca/P molar ratio of the crystals varied from 1.5 to 1.6. According to this study, PProP presents bioactivity in vitro, and its fibers offer sites for CaP nucleation like the collagen fibers in bone. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013 , 51, 1318–1327 相似文献
63.
Kai Zhang Xuefen Wang Yin Yang Lili Wang Meifang Zhu Benjamin S. Hsiao Benjamin Chu 《Journal of Polymer Science.Polymer Physics》2010,48(10):1118-1125
In this work, aligned and molecularly oriented bone‐like PLLA semihollow fiber yarns were manufactured continuously from an optimized homogeneous polymer‐solvent‐nonsolvent system [PLLA, CH2Cl2, and dimethyl formamide (DMF)] by a single capillary electrospinning via self‐bundling technique. Here, it should be emphasized that the self‐bundling electrospinning technique, a very facile electrospinning technique with a grounded needle (which is to induce the self‐bundling of polymer nanofibers at the beginning of electrospinning process), is used for the alignment and molecular orientation of the polymer fiber, and the take‐up speed of the rotating drum for the electrospun fiber yarn collection is very low (0.5 m/s). PLLA can be dissolved in DMF and CH2Cl2 mixed solvent with different ratios. By varying the ratios of mixed solvent system, PLLA electrospun semihollow fiber with the porous inner structure and compact shell wall could be formed, the thickness of the shell and the size of inner pores could be adjusted. The results of polarized FTIR and wide angle X‐ray diffraction investigations verified that as‐prepared PLLA semihollow fiber yarns were well‐aligned and molecularly oriented. Both the formation mechanism of semihollow fibers with core‐shell structure and the orientation mechanism of polymer chains within the polymer fibers were all discussed. The as‐prepared self‐bundling electrospun PLLA fiber yarns possessed enhanced mechanical performance compared with the corresponding conventional electrospun PLLA fibrous nonwoven membranes. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1118–1125, 2010 相似文献
64.
Poro-micromechanics allows for the quantification of poroelastic properties such as the Biot and Skempton coefficients, once a continuum micromechanics model for the material under consideration has been developed and validated. Employing such a model for the transversely isotropic elasticity of cortical and trabecular bone, we determine the tensors of Biot and Skempton coefficients as functions of the volume fractions of mineral, collagen, and the micropore space (Haversian and Volkmann canals, and the inter-trabecular space). Increase of microporosity, as experienced in osteoporosis, as well as decrease of mineral content, as experienced in osteomalacia, lead to an increase of Biot and Skempton coefficients, i. e. to magnification of the mechanical role of the marrow filling the micropore space. For quantification of the marrow pressure rise upon downfall, undrained conditions are appropriate, as can be shown by model predictions of non-destructive impact experiments. 相似文献
65.
Dendritic Glycopolymer as Drug Delivery System for Proteasome Inhibitor Bortezomib in a Calcium Phosphate Bone Cement: First Steps Toward a Local Therapy of Osteolytic Bone Lesions 下载免费PDF全文
66.
Supramolecular Polyelectrolyte Complexes of Bone Morphogenetic Protein‐2 with Sulfonated Polyrotaxanes to Induce Enhanced Osteogenic Differentiation 下载免费PDF全文
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The objective of this paper is to identify the effects of mechanical disuse and basic multi-cellular unit (BMU) activation threshold on the form of trabecular bone during menopause. A bone adaptation model with mechanical- biological factors at BMU level was integrated with finite element analysis to simulate the changes of trabecular bone structure during menopause. Mechanical disuse and changes in the BMU activation threshold were applied to the model for the period from 4 years before to 4 years after menopause. The changes in bone volume fraction, trabecular thickness and fractal dimension of the trabecular structures were used to quantify the changes of trabecular bone in three different cases associated with mechanical disuse and BMU activation threshold. It was found that the changes in the simulated bone volume fraction were highly correlated and consistent with clinical data, and that the trabecular thickness reduced signi-ficantly during menopause and was highly linearly correlated with the bone volume fraction, and that the change trend of fractal dimension of the simulated trabecular structure was in correspondence with clinical observations. The numerical simulation in this paper may help to better understand the relationship between the bone morphology and the mecha-nical, as well as biological environment; and can provide a quantitative computational model and methodology for the numerical simulation of the bone structural morphological changes caused by the mechanical environment, and/or the biological environment. 相似文献
70.
Domenico Franco Giovanna Calabrese Salvatore Petralia Giulia Neri Carmelo Corsaro Lucia Forte Stefano Squarzoni Salvatore Guglielmino Francesco Traina Enza Fazio Sabrina Conoci 《Molecules (Basel, Switzerland)》2021,26(4)
Hydroxyapatite (HA) is the main inorganic mineral that constitutes bone matrix and represents the most used biomaterial for bone regeneration. Over the years, it has been demonstrated that HA exhibits good biocompatibility, osteoconductivity, and osteoinductivity both in vitro and in vivo, and can be prepared by synthetic and natural sources via easy fabrication strategies. However, its low antibacterial property and its fragile nature restricts its usage for bone graft applications. In this study we functionalized a MgHA scaffold with gold nanorods (AuNRs) and evaluated its antibacterial effect against S. aureus and E. coli in both suspension and adhesion and its cytotoxicity over time (1 to 24 days). Results show that the AuNRs nano-functionalization improves the antibacterial activity with 100% bacterial reduction after 24 h. The toxicity study, however, indicates a 4.38-fold cell number decrease at 24 days. Although further optimization on nano-functionalization process are needed for cytotoxicity, these data indicated that Au-NRs nano-functionalization is a very promising method for improving the antibacterial properties of HA. 相似文献