X-ray computed microtomography datasets for osteogenic nanofibrous coated titanium implants.

Surface modifications of titanium implant influences the quality of osseointegration and are associated with favourable treatment prognosis in orthopaedic and cranio-maxillofacial cases. Hence, unlike previous works, the peri-implant region details of our novel osteogenic nanofibrous coated implants placed in rabbits (n = 6 + 1) were recorded over a 12-week period using a micro-CT imaging system. In this unique contribution, we have created a computed tomography (CT) library of rabbit's tibiae anatomy with osteogenic nanofibrous coated/uncoated implants and are introductory useful assets for investigating the correlation between osteogenic nanofibers coated implants and its effect on improved osseointegration. Apart from using this CT dataset to conduct serial 2D image studies, three-dimensional (3D) reconstructions, assessing segmentation algorithms and developing adequate image quantitation tools, there may be positive applications of these in comparative investigations of similar or related preclinical as well as future clinical studies, further design planning, development etc. required for evolution of implants beyond the present state of art.

Concomitant Effect of Quercetin- and Magnesium-Doped Calcium Silicate on the Osteogenic and Antibacterial Activity of Scaffolds for Bone Regeneration.

Quercetin is a bioflavonoid which has a broad spectrum of biological activity. Due to its lower chemical stability, it is usually encapsulated, or a metal-quercetin complex is formed to enhance its biological activity at a lower concentration. Here, our novel approach was to form a quercetin complex to magnesium-doped calcium silicate (CMS) ceramics through a coprecipitation technique so as to take advantage of quercetin's antibacterial activity within the antibacterial and osteogenic potential of the silicate. Due to quercetin's inherent metal-chelating ability, (Ca+Mg)/Si increased with quercetin concentration. Quercetin in magnesium-doped calcium silicate ceramic showed concentration-dependent pro-oxidant and antioxidant activity in SaOS-2 with respect to quercetin concentration. By optimizing the relative concentration, we were able to achieve 3-fold higher proliferation and 1.6-fold higher total collagen at day 14, and a 1.7-fold higher alkaline phosphatase production at day 7 with respect to polycaprolactone/polyvinylpyrrolidone (PCL/PVP) scaffold. Quercetin is effective against Gram-positive bacteria such as S. aureus. Quercetin is coupled with CMS provided similar effect with lower quercetin concentration than quercetin alone. Quercetin reduced bacterial adhesion, proliferation and biofilm formation. Therefore, quercetin-coupled magnesium-doped calcium silicate not only enhanced osteogenic potential, but also reduced bacterial adhesion and proliferation.

Chemical Fingerprinting of Polymers Using Electron Energy-Loss Spectroscopy.

Electron energy-loss spectroscopy (EELS) is becoming an important tool in the characterization of polymeric materials. The sensitivity of EELS to changes in the chemical structure of polymeric materials dictates its applicability. In particular, it is important for compositional analysis to have reference spectra of pure components. Here, we report the spectra of the carbon K-edge of six polymers (polyethylene, polypropylene, polybutylene terephthalate, and polylactic acid) including copolymers (styrene acrylonitrile and acrylonitrile butadiene styrene), to be used as reference spectra for future EELS studies of polymers. We have successfully decomposed the carbon K-edge of each of the polymers and assigned the observed peaks to bonding transitions. The spectra have been acquired in standard experimental conditions, and electron beam damage has been taken into account during establishment of spectral-structural relationships. We found that the more commonly available low-energy resolution spectrometers are adequate to chemically fingerprint linear saturated hydrocarbons such as PE, PP, and PLA. We have thus moved a step closer toward creating an atlas of polymer EELS spectra, which can be subsequently used for chemical bond mapping of polymeric materials with nanoscale spatial resolution.

Probing Kinetics and Mechanism of Formation of Mixed Metallic Nanoparticles in a Polymer Membrane by Galvanic Replacement between Two Immiscible Metals: Case Study of Nickel/Silver Nanoparticle Synthesis.

Galvanic replacement between metals has received notable research interest for the synthesis of heterometallic nanostructures. The growth pattern of the nanostructures depends on several factors such as extent of lattice mismatch, adhesive interaction between the metals, cohesive forces of the individual metals, etc. Due to the difficulties in probing ultrafast kinetics of the galvanic replacement reaction and particle growth in solution, real-time mechanistic investigations are often limited. As a result, the growth mechanism of one metal on the surface of another metal at the nanoscale is poorly understood so far. In the present work, we could successfully probe the galvanic replacement of silver ions with nickel nanoparticles, stabilized in a polymer membrane, using two complementary methods, namely, small-angle X-ray scattering (SAXS) and radiolabeling, and the results are supported by density functional theory (DFT) computations. The silver-nickel system has been chosen for the present investigation because of the high degree of bulk immiscibility caused by the large lattice mismatch (15.9%) and the weak adhesive interaction, which makes it a perfect model system for immiscible metal pairs. Membrane, as a host medium, plays a crucial role in retarding the kinetics of atomic and particle rearrangements (nucleation and growth) due to slower mobility of the atoms (monomers) and particles within the polymer network. This allowed us to examine the real-time concentration of silver monomers during galvanic replacement of silver ions with nickel nanoparticles and evolution of Ni/Ag nanoparticles. From combined experiment and DFT computations, it has been demonstrated, for the first time to the best of our knowledge, that the majority of silver atoms, which are produced on the nickel nanoparticle surface by galvanic reactions, do not form traditional core-shell nanostructures with nickel and undergo a self-governing sequential nucleation and growth of silver nanoparticles via formation of intermediate prenucleation silver clusters, leading to the formation of mixed metallic nanoparticles in the membrane. The surface of NiNPs has a heterogeneous effect on the silver nucleation pathway, which is evident from the reduced critical free energy barrier of nucleation (ΔGcrit). The present work establishes an original mechanistic pathway based on a sequential nucleation model for formation of mixed metallic nanoparticles by the galvanic replacement route, which opens up future possibilities for size-controlled synthesis in mixed systems.

Three Dimensional Quercetin-Functionalized Patterned Scaffold: Development, Characterization, and In Vitro Assessment for Neural Tissue Engineering.

Regeneration of injured neuronal areas is a big challenge owing to the complex structure and function of the nervous system along with the limited regeneration capacity of neural cells. Recent reports show that patterned and functionalized scaffolds could control neural cell directional growth. In this study, aligned nanofibers (ANFs) were fabricated using a versatile and cost-effective approach, electrospinning, and further processed to make a patterned hybrid scaffold (HANF). The patterned scaffold had circular rings of ANFs reinforced in a biocompatible gellan-gelatin hydrogel matrix to provide adequate mechanical strength and contact guidance for adhesion and growth of neural cells in vitro. Quercetin was loaded into the nanofibrous scaffold to provide a functional agent that supported regeneration of neural cells. The reinforced ANFs enhanced the mechanical strength of the scaffold and provided a cylindrical nerve conduit structure to support neuronal cell growth. The influence of scaffold topology on cell behavior was assessed in in vitro cell culture conditions that revealed that the functionalized patterned scaffolds favored directed neurite cell growth/extension with favored cell culture morphology and showed no cytotoxicity toward neural cells. The results ultimately indicated that the fabricated scaffold has potential for guiding nerve tissue growth and can be used as nerve regeneration scaffolds.

Dental Pulp Stem Cells in Customized 3D Nanofibrous Scaffolds for Regeneration of Peripheral Nervous System.

Dental pulp stem cells (DPSCs) are adult multipotent stem cells of neuroectodermal origin; they provide an encouraging perspective in the domain of nerve tissue engineering. DPSCs could be transplanted in biodegradable electrospun neuro-supportive scaffold (optimized in various 3D geometries like coating on the surface of titanium implant, hollow/solid tubes, etc.) for enhanced in vivo recovery of peripheral nerves. Herein, we describe the fabrication of uniform bead-free nanofibrous scaffold which supports DPSCs, proliferation, and their subsequent neural differentiation and thus could be utilized for enhanced regeneration of peripheral nervous system.

Dilution-Induced Physico-Chemical Changes of Metal Oxide Nanoparticles Due to Homeopathic Preparation Steps of Trituration and Succussion.

BACKGROUND: Although the presence of starting materials in extreme dilutions of homeopathic medicines has been established, the physico-chemical changes of these materials induced by the manufacturing steps-that is, solid-solid mixing involving grinding (trituration) and slurry mixing involving impact (succussion), followed by dilution-are still unknown. METHODS: We subjected cupric oxide and zinc oxide nanoparticles (NPs) to the homeopathic processes of trituration and succussion, followed by dilution up to 6 cH. Particle image velocimetry was employed to analyze the fluid motion during succussion and its effect on the NPs. The resulting microstructural and chemical changes at different dilution steps were determined by X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy and transmission electron microscopy. RESULTS: The succussion triggered multi-sized bubble generation and turbulent fluid motion up to a duration of 400 ms, with maximum average velocity of 0.23 m/s. Due to 1% transfer of kinetic energy from a moving eddy with this velocity, upon collision, the rate of temperature change in a particle of size 1 µm and 1 nm was predicted to rise by approximately 102 K/s and 106 K/s respectively. During trituration, the oxide NPs reduced to metals and did not aggregate by remaining within lactose, but they converted to oxidized finer NPs after impact. Silicate chains leached from the vial cross-linked after third dilution, forming large macro-particles and encapsulating the NPs that were retained and carried at higher dilution steps. CONCLUSION: The results showed that the NPs sustained significant rate of temperature change due to energy transfer from moving eddies during succussion. Different physico-chemical changes, such as size reduction, successive reduction and oxidation of NPs, and morphological changes, were achieved through trituration and succussion. The retention of NPs within cross-linked poly-siloxane chains reveals the importance of both the borosilicate glass vial and the ethanol solution during preparation of homeopathic medicines.

Accentuated osseointegration in osteogenic nanofibrous coated titanium implants.

Anchoring of endosseous implant through osseointegration continues to be an important clinical need. Here, we describe the development of superior endosseous implant demonstrating enhance osseointegration, achieved through surface modification via coating of osteogenic nanofibres. The randomized bio-composite osteogenic nanofibres incorporating polycaprolactone, gelatin, hydroxyapatite, dexamethasone, beta-glycerophosphate and ascorbic acid were electrospun on titanium implants mimicking bone extracellular matrix and subsequently induced osteogenesis by targeting undifferentiated mesenchymal stem cells present in the peri-implant niche to regenerate osseous tissue. In proof-of-concept experiment on rabbit study models (n = 6), micro-computed tomography (Micro-CT), histomorphometric analysis and biomechanical testing in relation to our novel osteogenic nanofibrous coated implants showed improved results when compared to uncoated controls. Further, no pathological changes were detected during gross examination and necropsy on peri-implant osseous tissues regenerated in response to such coated implants. The findings of the present study confirm that osteogenic nanofibrous coating significantly increases the magnitude of osteogenesis in the peri-implant zone and favours the dynamics of osseointegration.

Oral dosing of pentoxifylline, a pan-phosphodiesterase inhibitor restores bone mass and quality in osteopenic rabbits by an osteogenic mechanism: A comparative study with human parathyroid hormone.

The non-selective phosphodiesterase inhibitor pentoxifylline (PTX) is used for the treatment of intermittent claudication due to artery occlusion. Previous studies in rodents have reported salutary effects of the intraperitoneal administration of PTX in segmental bone defect and fracture healing, as well as stimulation of bone formation. We determined the effect of orally dosed PTX in skeletally mature ovariectomized (OVX) rabbits with osteopenia. The half-maximal effective concentration (EC50) of PTX in rabbit bone marrow stromal cells was 3.07 ±â€¯1.37 nM. The plasma PTX level was 2.05 ±â€¯0.522 nM after a single oral dose of 12.5mg/kg, which was one-sixth of the adult human dose of PTX. Four months of daily oral dosing of PTX at 12.5 mg/kg to osteopenic rabbits completely restored bone mineral density, bone mineral content (BMC), microarchitecture and bone strength to the level of the sham-operated (ovary intact) group. The bone strength to BMC relationship between PTX and sham was similar. The bone restorative effect of PTX was observed in both axial and appendicular bones. In osteopenic rabbits, PTX increased serum amino-terminal propeptide, mineralized nodule formation by stromal cells and osteogenic gene expression in bone. PTX reversed decreased calcium weight percentage and poor crystal packing found in osteopenic rabbits. Furthermore, similar to parathyroid hormone (PTH), PTX had no effect on bone resorption. Taken together, our data show that PTX completely restored bone mass, bone strength and bone mineral properties by an anabolic mechanism. PTX has the potential to become an oral osteogenic drug for the treatment of post-menopausal osteoporosis.

Gloriosa superba Mediated Synthesis of Platinum and Palladium Nanoparticles for Induction of Apoptosis in Breast Cancer.

Green chemistry approaches for designing therapeutically significant nanomedicine have gained considerable attention in the past decade. Herein, we report for the first time on anticancer potential of phytogenic platinum nanoparticles (PtNPs) and palladium nanoparticles (PdNPs) using a medicinal plant Gloriosa superba tuber extract (GSTE). The synthesis of the nanoparticles was completed within 5 hours at 100°C which was confirmed by development of dark brown and black colour for PtNPs and PdNPs, respectively, along with enhancement of the peak intensity in the UV-visible spectra. High-resolution transmission electron microscopy (HRTEM) showed that the monodispersed spherical nanoparticles were within a size range below 10 nm. Energy dispersive spectra (EDS) confirmed the elemental composition, while dynamic light scattering (DLS) helped to evaluate the hydrodynamic size of the particles. Anticancer activity against MCF-7 (human breast adenocarcinoma) cell lines was evaluated using MTT assay, flow cytometry, and confocal microscopy. PtNPs and PdNPs showed 49.65 ± 1.99% and 36.26 ± 0.91% of anticancer activity. Induction of apoptosis was most predominant in the underlying mechanism which was rationalized by externalization of phosphatidyl serine and membrane blebbing. These findings support the efficiency of phytogenic fabrication of nanoscale platinum and palladium drugs for management and therapy against breast cancer.

Development of hybrid scaffold with biomimetic 3D architecture for bone regeneration.

In the present study, a biomimetic three-dimensional hybrid scaffold has been designed considering the bone natural architecture with favorable interconnected porous structure, nano-microscale features and mechanical strength. The chief components of the hybrid scaffold are core-sheath nanofibers and hydrogel, suitably arranged to create a bone like microenvironment. Specifically, the core-sheath nanofibers were coiled tightly into a ring to mimic the osteon, and reinforced in a hydrogel matrix. Morphological analysis using SEM and 4D-X-ray microscopy revealed that the hybrid scaffold consists of coiled rings of nanofibers in highly porous hydrogel matrix showing structural similarity to osteons. The reinforcement of electrospun nanofibers in hydrogel influenced the mechanical properties of scaffold. The potential application of the biomimetic hybrid scaffold, and the role of its specific architecture, was subsequently investigated in vitro using a human osteosarcoma fibroblast cell line. Furthermore, DNA quantification, alkaline-phosphatase and alizarin assay validated the potential of fabricated scaffold for bone tissue-regeneration.

Osteogenic Nanofibrous Coated Titanium Implant Results in Enhanced Osseointegration: In Vivo Preliminary Study in a Rabbit Model.

A titanium implant surface when coated with biodegradable, highly porous, osteogenic nanofibrous coating has shown enhanced intrinsic osteoinductive and osteoconductive properties. This coating mimics extracellular matrix resulting in differentiation of stem cells present in the peri-implant niche to osteoblast and hence results in enhanced osseointegration of the implant. The osteogenic nanofibrous coating (ONFC) consists of poly-caprolactone, gelatin, nano-sized hydroxyapatite, dexamethasone, ascorbic acid and beta-glycerophosphate. ONFC exhibits optimum mechanical properties to support mesenchymal stem cells and steer their osteogenic differentiation. ONFC was subjected to various characterization tests like scanning electron microscopy, Fourier-transform infrared spectroscopy, x-ray diffractometry, thermal degradation, biomineralization, mechanical properties, wettability and proliferation assay. In pre-clinical animal trials, the coated implant showed enhanced new bone formation when placed in the tibia of rabbit. This novel approach toward implant bone integration holds significant promise for its easy and economical coating thus marking the beginning of new era of electrospun osteogenic nanofibrous coated bone implants.

Metal nanoparticle induced hormetic activation: a novel mechanism of homeopathic medicines.

BACKGROUND: High-potency homeopathic remedies, 30c and 200c have enormous dilution factors of 1060 and 10400 respectively. Therefore, the presence of physical entities in them is inconceivable. As a result, their efficacy is highly debated and often dismissed as a placebo. Despite several hypotheses postulated to explain the claimed homeopathic efficacy, none have satisfactorily answered the qualms of the sceptics. Against all beliefs and principles of conventional dilution, we have shown that nanoparticles (NPs) of the starting metals are unequivocally found in the 30c and 200c remedies at concentrations of a few pg/ml. In this paper, our aim was to answer the important question of whether such negligible metal concentrations elicit a biological response. METHODS: Metal-based homeopathic medicines (30c and 200c) were analysed at doses between 0.003%v/v and 10%v/v in in-vitro HepG2 cell-line. Upon treatment, cell response was estimated by MTT assay, FACS and total intracellular protein. Experiments were performed to discern whether the hormesis was a cell-activation or a proliferation effect. RESULTS: Remedies at doses containing a few femtograms/ml levels of the starting metals induced a proliferation-independent hormetic activation by increasing the intracellular protein synthesis. The metal concentrations (at fg/ml) were a billion-fold lower than the studies with synthetic NPs (at µg/ml). Further, we also highlight a few plausible mechanisms initiating a hormetic response at a billion-fold lower dose. CONCLUSIONS: Hormetic activation has been shown for the first time with standard homeopathic high-potency remedies. These findings should have a profound effect in understanding these extreme dilutions from a biological perspective.

Hemostatic Efficacy of Nanofibrous Matrix in Rat Liver Injury Model.

This present study examined the hemostatic efficacy of nanofibrous matrix in a rat liver model. The nanofibrous matrix comprising gelatin and polycaprolactone was prepared by electrospinning method. Twelve animals underwent surgery and were followed-up for a month. Time taken to cease bleeding, activated partial thromboplastin time, prothrombin time, and fibrinogen concentration were measured. Histopathological examination of liver was also done of treated and control animals. All test animals showed very rapid hemostasis after application of electrospun sheet. Histopathological study showed quick recovery of liver wound in the test group as compared to the control group. The nanofibrous matrix has proven to be not only safe and effective as hemostat but has also shown its potential for liver regeneration.

Bioconductive 3D nano-composite constructs with tunable elasticity to initiate stem cell growth and induce bone mineralization.

Bioactive 3D composites play an important role in advanced biomaterial design to provide molecular coupling and improve integrity with the cellular environment of the native bone. In the present study, a hybrid lyophilized polymer composite blend of anionic charged sodium salt of carboxymethyl chitin and gelatin (CMChNa-GEL) reinforced with nano-rod agglomerated hydroxyapatite (nHA) has been developed with enhanced biocompatibility and tunable elasticity. The scaffolds have an open, uniform and interconnected porous structure with an average pore diameter of 157±30µm and 89.47+0.03% with four dimensional X-ray. The aspect ratio of ellipsoidal pores decrease from 4.4 to 1.2 with increase in gelatin concentration; and from 2.14 to 1.93 with decrease in gelling temperature. The samples were resilient with elastic stain at 1.2MPa of stress also decreased from 0.33 to 0.23 with increase in gelatin concentration. The crosslinker HMDI (hexamethylene diisocyanate) yielded more resilient samples at 1.2MPa in comparison to glutaraldehyde. Increased crosslinking time from 2 to 4h in continuous compression cycle show no improvement in maximum elastic stain of 1.2MPa stress. This surface elasticity of the scaffold enables the capacity of these materials for adherent self renewal and cultivation of the NTERA-2 cL.D1 (NT2/D1), pluripotent embryonal carcinoma cell with biomechanical surface, as is shown here. Proliferation with MG-63, ALP activity and Alizarin red mineralization assay on optimized scaffold demonstrated ***p<0.001 between different time points thus showing its potential for bone healing. In pre-clinical study histological bone response of the scaffold construct displayed improved activity of bone regeneration in comparison to self healing of control groups (sham) up to week 07 after implantation in rabbit tibia critical-size defect. Therefore, this nHA-CMChNa-GEL scaffold composite exhibits inherent and efficient physicochemical, mechanical and biological characteristics based on gel concentrations, gelatin mixing and gelling temperature thus points to creating bioactive 3D scaffolds with tunable elasticity for orthopedic applications.

Mathematical Modeling and Simulation of an Occlusion Device in a Blood Vessel.

An occlusion device is placed in an abnormal opening of the heart or its surrounding vessels to regain normal blood flow. There are various occlusion devices available for treatment of various congenital heart defects like PDA, ASD, etc. However, they have limitations like residual shunting, erosion of tissue, displacement and breakage of device, thrombus formation and sudden death. To improve efficiency and to reduce failure of occlusion devices, it is important to simulate blood flow through defect before and after placement of device. It is also important to evaluate stresses and forces exerted by blood flow on device and by the device on the vessel wall. Contact friction between device and vessel wall plays a crucial role in anchoring the device. The objective is to develop a framework to determine conditions to restrict dislocation of device in terms of contact friction. Typical occlusion devices are porous initially and later due to thrombogenesis, their porosity reduces until eventually it acts as a natural permanent plug. Thus, a porous sponge is a good model for an occlusion device. The mathematical model developed here is for differential pressure causing incipient movement of device, and minimum value of contact friction for restricting movement of the device for two shapes, cylindrical and conical, in uncompressed as well as pre compressed forms. The model for differential pressure is fitted by conducting physical experiment with sponge. Mathematically, porosity is modeled using viscous resistance and inertial resistance which are calculated by experiment and simulation with ANSYS. We perform computer experiments (simulations) on a cylindrical device in a cylindrical vessel and on a conical device in a tapered vessel to determine the differential pressure across the device and hence contact friction with varied porosity under boundary conditions as in body. The contact friction required to retain device is lesser in case of conical device compared to cylindrical device. As compression of device increases, friction require to retain it decreases. Hence, lesser porosity results in larger differential pressure and lesser compression which will eventually need higher friction values to retain the device.

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

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

Odanacatib Restores Trabecular Bone of Skeletally Mature Female Rabbits With Osteopenia but Induces Brittleness of Cortical Bone: A Comparative Study of the Investigational Drug With PTH, Estrogen, and Alendronate.

Cathepsin K (CK), a lysosomal cysteine protease, is highly expressed in mature osteoclasts and degrades type 1 collagen. Odanacatib (ODN) is a selective and reversible CK inhibitor that inhibits bone loss in preclinical and clinical studies. Although an antiresorptive, ODN does not suppress bone formation, which led us to hypothesize that ODN may display restorative effect on the osteopenic bones. In a curative study, skeletally mature New Zealand rabbits were ovarectomized (OVX) and after induction of bone loss were given a steady-state exposure of ODN (9 mM/d) for 14 weeks. Sham-operated and OVX rabbits treated with alendronate (ALD), 17b-estradiol (E2), or parathyroid hormone (PTH) served as various controls. Efficacy was evaluated by assessing bone mineral density (BMD), bone microarchitecture (using micro-computed tomography), fluorescent labeling of bone, and biomechanical strength. Skeletal Ca/P ratio was measured by scanning electron microscopy (SEM) with X-ray microanalysis, crystallinity by X-ray diffraction, and bone mineral density distribution (tissue mineralization) by backscattered SEM. Between the sham and ODN-treated osteopenic groups, lumbar and femur metaphyseal BMD, Ca/P ratio, trabecular microstructure and geometric indices, vertebral compressive strength, trabecular lining cells, cortical parameters (femoral area and thickness and periosteal deposition), and serum P1NP were largely comparable. Skeletal improvements in ALD-treated or E2-treated groups fell significantly short of the sham/ODN/PTH group. However, the ODN group displayed reduced ductility and enhanced brittleness of central femur, which might have been contributed by higher crytallinity and tissue mineralization. Rabbit bone marrow stromal cells expressed CK and when treated with ODN displayed increased formation of mineralized nodules and decreased apoptosis in serum-deficient medium compared with control. In vivo, ODN did not suppress remodeling but inhibited osteoclast activity more than ALD. Taken together, we show that ODN reverses BMD, skeletal architecture, and compressive strength in osteopenic rabbits; however, it increases crystallinity and tissue mineralization, thus leading to increased cortical bone brittleness.

Characterization of mechanical properties of materials using ultrasound broadband spectroscopy.

This article explores the characterization of homogenous materials (metals, alloys, glass and polymers) by a simple broadband ultrasonic interrogation method. The novelty lies in the use of ultrasound in a continuous way with very low input power (0 dBm or less) and analysis of the transmitted acoustic wave spectrum for material property characterization like speed of sound, density and dimensions of a material. Measurements were conducted on various thicknesses of samples immersed in liquid where continuous-wave, frequency swept ultrasonic energy was incident normal to the sample surface. The electro-acoustic transmission response is analyzed in the frequency domain with respect to a specifically constructed multi-layered analytical model. From the acoustic signature of the sample materials, material properties such as speed of sound and acoustic impedance can be calculated with experimentally derived values found to be in general agreement with the literature and with pulse-echo technique establishing the basis for a non-contact and non-destructive technique for material characterization. Further, by looking at the frequency spacing of the peaks of water when the sample is immersed, the thickness of the sample can be calculated independently from the acoustic response. This technique can prove to be an effective non-contact, non-destructive and fast material characterization technique for a wide variety of materials.