Ibandronate and cementless total hip arthroplasty: densitometric measurement of periprosthetic bone mass and new therapeutic approach to the prevention of aseptic loosening

PubMed Central

Muratore, Maurizio; Quarta, Eugenio; Quarta, Laura; Calcagnile, Fabio; Grimaldi, Antonella; Orgiani, M. Antonio; Marsilio, Antonio; Rollo, Giuseppe

2012-01-01

Summary Studies of the mechanisms of periprosthetic bone loss have led to the development of pharmacologic strategies intended to enhance bone mass recovery after surgery and consequently prevent aseptic loosening and prolong the implant survival. Bisphosphonates, potent anti-resorptive drugs widely used in the treatment of osteoporosis and other disorders of bone metabolism, were shown to be particularly effective in reducing periprosthetic bone resorption in the first year after hip and knee arthroplasty, both cemented and cementless. Based on these results, we investigated the inhibitory effects of ibandronate on periprosthetic bone loss in a 2-year study of postmenopausal women that underwent cementless total hip arthroplasty. In the first 6 months both groups (A, treated with ibandronate 3 mg i.v. within five days after surgery and then with oral ibandronate 150 mg/month, plus calcium and vitamin D supplementation; and B, treated with calcium and vitamin D supplementation only) experienced bone loss, though to a lesser extent in group A. After 12 months, group A showed a remarkable BMD recovery, that was statistically significant versus baseline values (about +1, 74% of global BMD) and most evident in region R1 (+3, 81%) and R2 (+4, 12%); in group B, on the contrary, BMD values were unchanged compared with those at 6 months post-surgery. Quality of life scores also showed a greater improvement in group A, both at 6 and 12 months after surgery, likely because of the pain-reducing effects of ibandronate treatment. PMID:22783337

A rapid and sustained improvement of calcification propensity score (serum T50 ) after successful kidney transplantation: Reanalysis of a randomized controlled trial of ibandronate.

PubMed

Smerud, Knut T; Åsberg, Anders; Kile, Håkon; Pasch, Andreas; Dahle, Dag O; Bollerslev, Jens; Godang, Kristin; Hartmann, Anders

2017-12-01

A serum test called T 50 assesses the overall propensity for calcification of the blood and is associated with cardiovascular outcomes. We aimed to examine T 50 over time in kidney transplant recipients and also address any effects of ibandronate. Serum samples taken from kidney transplant patients included in a prospective, randomized placebo controlled study of ibandronate were analyzed in retrospect. Adequate analyses were performed at baseline (approximately 3 weeks after transplantation) in 129 patients, at 10 weeks in 127 patients and at 1 year in 123 patients. There were no statistical differences between ibandronate and placebo treatment in terms of T 50 at 10 weeks (P = .094) or at 1 year (P = .116). Baseline T 50 was a significant covariate (P < .0001) for T 50 scores at 10 weeks and 1 year. In the total cohort, there was a highly significant (P < .0001) increase in T 50 of 26.6% after 10 weeks and T 50 remained stable after 1 year. T 50 change was inversely correlated to phosphate of -0.515 (P < .0001) and to change in serum albumin (P < .03). We found that T 50 increased from baseline to 10 weeks after transplantation with no further change after 1 year. Ibandronate had no effect on T 50 . © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

In vitro and in vivo experimental studies on trabecular meshwork degeneration induced by benzalkonium chloride (an American Ophthalmological Society thesis).

PubMed

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

2012-12-01

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

The utility of changes in serum levels of C-terminal telopeptide of type I collagen in predicting patient response to oral monthly ibandronate therapy.

PubMed

Hochberg, Marc C; Silverman, Stuart L; Barr, Charles E; Miller, Paul D

2010-01-01

Bone turnover markers may provide a more rapid indication of patient response to osteoporosis treatment than bone mineral density (BMD) measurements. This post hoc analysis of data from the MOBILE (Monthly Oral iBandronate In LadiEs) study assessed the relationship between increases in BMD at 12 mo from baseline after starting ibandronate treatment and changes in bone resorption marker serum C-terminal telopeptide of type I collagen (sCTX) from baseline at 3 and 6 mo. MOBILE enrolled postmenopausal women aged 55-80 yr with mean lumbar spine (LS) BMD T-score of -2.5 to -5.0. This analysis included women who received 150-mg monthly oral ibandronate (n=323). A high proportion of women were classified as BMD responders after 1 yr (BMD increase was >/=0%, i.e., 74-91% depending on skeletal site; BMD increase was >/=3%, i.e., 34-67%). Women with larger decreases in sCTX were more likely to be BMD responders. The percent increase in LS BMD at 12 mo was significantly associated with the percent decrease in sCTX at 3 mo from baseline (Pearson correlation coefficient: -0.19, p=0.0016). In linear regression models, percent decrease in sCTX at 3 mo from baseline was a significant predictor of 1-yr LS BMD response (R(2)=0.61, p=0.0007). These data suggest that 3-mo changes in sCTX levels are associated with 1-yr LS BMD increases in postmenopausal women treated with once-monthly oral ibandronate. The International Society for Clinical Densitometry. Published by Elsevier Inc. All rights reserved.

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

PubMed Central

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

2012-01-01

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

[Preservatives in ophthalmology].

PubMed

Messmer, E M

2012-11-01

Preservatives are a legal requirement for eye drops in multidose containers. Moreover, they are necessary for stabilization and intraocular penetration for a number of ophthalmic preparations. Most preservatives act in a relatively unspecific manner as detergents or by oxidative mechanisms and thereby cause side effects at the ocular surface. They may also affect the lens, trabecular meshwork and the retina. Benzalkonium chloride is the most commonly used preservative in ophthalmology and is more toxic than other or newer preservatives, such as polyquaternium-1 (Polyquad), sodium perborate, oxychloro-complex (Purite®) and SofZia. Preservative-free topical medication is highly recommended for patients with ocular surface disease, frequent eye drop administration, proven allergy to preservatives and contact lens wear.

Assessment of OPG, RANKL, bone turnover markers serum levels and BMD after treatment with strontium ranelate and ibandronate in patients with postmenopausal osteoporosis.

PubMed

Stuss, Michał; Sewerynek, Ewa; Król, Iwona; Stępień-Kłos, Wioletta; Jędrzejczyk, Sławomir

2016-01-01

The aim of this study was to evaluate quantitative changes in OPG and RANKL proteins after treatment with strontium ranelate (SR) and ibandronate in patients with postmenopausal osteoporosis. A total of 89 women with postmenopausal osteoporosis (PO), aged 51-85 years, patients of the Outpatient Clinic of Osteoporosis of the Military Teaching Hospital in Lodz, were enrolled in the study. The patients were randomly assigned to different therapies: ibandronate and (SR). Patients of the control group received only calcium and vitamin D3 supplements. The patients' visits were repeated after three and six months. Measurements of beta-CTX (C-terminal Telopeptide of type 1 collagen), osteocalcin, RANKL, osteoprotegerin (OPG), alkaline phosphatase concentrations in serum, as well as of total 24-hour calcium and phosphate levels in serum and urine, were carried out in material collected at baseline and after three and six months of therapy. Left hip and lumbar spine densitometry was done twice (at baseline visit and after six months). In all three groups there were no significant differences noted in the concentrations of OPG and RANKL serum protein levels during the study period. Both negative and positive correlations or tendencies of correlations were found between OPG serum concentrations and BMD changes in the SR group. Both ibandronate and SR do not seem to cause any significant changes in OPG and RANKL protein serum levels during the first six months of treatment. OPG may play a role in osteoclast activity suppression in the course of treatment with ibandronate in patients with PO. OPG may play an important role in the mechanism of SR therapy and may be viewed as a potentially valuable parameter for monitoring and predicting the course of treatment with SR in PO.

Trabecular Bone Score (TBS)—A Novel Method to Evaluate Bone Microarchitectural Texture in Patients With Primary Hyperparathyroidism

PubMed Central

Boutroy, Stephanie; Zhang, Chiyuan; McMahon, Donald Jay; Zhou, Bin; Wang, Ji; Udesky, Julia; Cremers, Serge; Sarquis, Marta; Guo, Xiang-Dong Edward; Hans, Didier

2013-01-01

Context: In the milder form of primary hyperparathyroidism (PHPT), cancellous bone, represented by areal bone mineral density at the lumbar spine by dual-energy x-ray absorptiometry (DXA), is preserved. This finding is in contrast to high-resolution peripheral quantitative computed tomography (HRpQCT) results of abnormal trabecular microstructure and epidemiological evidence for increased overall fracture risk in PHPT. Because DXA does not directly measure trabecular bone and HRpQCT is not widely available, we used trabecular bone score (TBS), a novel gray-level textural analysis applied to spine DXA images, to estimate indirectly trabecular microarchitecture. Objective: The purpose of this study was to assess TBS from spine DXA images in relation to HRpQCT indices and bone stiffness in radius and tibia in PHPT. Design and Setting: This was a cross-sectional study conducted in a referral center. Patients: Participants were 22 postmenopausal women with PHPT. Main Outcome Measures: Outcomes measured were areal bone mineral density by DXA, TBS indices derived from DXA images, HRpQCT standard measures, and bone stiffness assessed by finite element analysis at distal radius and tibia. Results: TBS in PHPT was low at 1.24, representing abnormal trabecular microstructure (normal ≥1.35). TBS was correlated with whole bone stiffness and all HRpQCT indices, except for trabecular thickness and trabecular stiffness at the radius. At the tibia, correlations were observed between TBS and volumetric densities, cortical thickness, trabecular bone volume, and whole bone stiffness. TBS correlated with all indices of trabecular microarchitecture, except trabecular thickness, after adjustment for body weight. Conclusion: TBS, a measurement technology readily available by DXA, shows promise in the clinical assessment of trabecular microstructure in PHPT. PMID:23526463

Complete Volumetric Decomposition of Individual Trabecular Plates and Rods and Its Morphological Correlations With Anisotropic Elastic Moduli in Human Trabecular Bone

PubMed Central

Liu, X Sherry; Sajda, Paul; Saha, Punam K; Wehrli, Felix W; Bevill, Grant; Keaveny, Tony M; Guo, X Edward

2008-01-01

Trabecular plates and rods are important microarchitectural features in determining mechanical properties of trabecular bone. A complete volumetric decomposition of individual trabecular plates and rods was used to assess the orientation and morphology of 71 human trabecular bone samples. The ITS-based morphological analyses better characterize microarchitecture and help predict anisotropic mechanical properties of trabecular bone. Introduction Standard morphological analyses of trabecular architecture lack explicit segmentations of individual trabecular plates and rods. In this study, a complete volumetric decomposition technique was developed to segment trabecular bone microstructure into individual plates and rods. Contributions of trabecular type–associated morphological parameters to the anisotropic elastic moduli of trabecular bone were studied. Materials and Methods Seventy-one human trabecular bone samples from the femoral neck (FN), tibia, and vertebral body (VB) were imaged using μCT or serial milling. Complete volumetric decomposition was applied to segment trabecular bone microstructure into individual plates and rods. The orientation of each individual trabecula was determined, and the axial bone volume fractions (aBV/TV), axially aligned bone volume fraction along each orthotropic axis, were correlated with the elastic moduli. The microstructural type–associated morphological parameters were derived and compared with standard morphological parameters. Their contributions to the anisotropic elastic moduli, calculated by finite element analysis (FEA), were evaluated and compared. Results The distribution of trabecular orientation suggested that longitudinal plates and transverse rods dominate at all three anatomic sites. aBV/TV along each axis, in general, showed a better correlation with the axial elastic modulus (r 2 = 0.95∼0.99) compared with BV/TV (r 2 = 0.93∼0.94). The plate-associated morphological parameters generally showed higher

Complete volumetric decomposition of individual trabecular plates and rods and its morphological correlations with anisotropic elastic moduli in human trabecular bone.

PubMed

Liu, X Sherry; Sajda, Paul; Saha, Punam K; Wehrli, Felix W; Bevill, Grant; Keaveny, Tony M; Guo, X Edward

2008-02-01

Trabecular plates and rods are important microarchitectural features in determining mechanical properties of trabecular bone. A complete volumetric decomposition of individual trabecular plates and rods was used to assess the orientation and morphology of 71 human trabecular bone samples. The ITS-based morphological analyses better characterize microarchitecture and help predict anisotropic mechanical properties of trabecular bone. Standard morphological analyses of trabecular architecture lack explicit segmentations of individual trabecular plates and rods. In this study, a complete volumetric decomposition technique was developed to segment trabecular bone microstructure into individual plates and rods. Contributions of trabecular type-associated morphological parameters to the anisotropic elastic moduli of trabecular bone were studied. Seventy-one human trabecular bone samples from the femoral neck (FN), tibia, and vertebral body (VB) were imaged using muCT or serial milling. Complete volumetric decomposition was applied to segment trabecular bone microstructure into individual plates and rods. The orientation of each individual trabecula was determined, and the axial bone volume fractions (aBV/TV), axially aligned bone volume fraction along each orthotropic axis, were correlated with the elastic moduli. The microstructural type-associated morphological parameters were derived and compared with standard morphological parameters. Their contributions to the anisotropic elastic moduli, calculated by finite element analysis (FEA), were evaluated and compared. The distribution of trabecular orientation suggested that longitudinal plates and transverse rods dominate at all three anatomic sites. aBV/TV along each axis, in general, showed a better correlation with the axial elastic modulus (r(2) = 0.95 approximately 0.99) compared with BV/TV (r(2) = 0.93 approximately 0.94). The plate-associated morphological parameters generally showed higher correlations with the

Experimental and numerical characterisation of the elasto-plastic properties of bovine trabecular bone and a trabecular bone analogue.

PubMed

Kelly, Nicola; McGarry, J Patrick

2012-05-01

The inelastic pressure dependent compressive behaviour of bovine trabecular bone is investigated through experimental and computational analysis. Two loading configurations are implemented, uniaxial and confined compression, providing two distinct loading paths in the von Mises-pressure stress plane. Experimental results reveal distinctive yielding followed by a constant nominal stress plateau for both uniaxial and confined compression. Computational simulation of the experimental tests using the Drucker-Prager and Mohr-Coulomb plasticity models fails to capture the confined compression behaviour of trabecular bone. The high pressure developed during confined compression does not result in plastic deformation using these formulations, and a near elastic response is computed. In contrast, the crushable foam plasticity models provide accurate simulation of the confined compression tests, with distinctive yield and plateau behaviour being predicted. The elliptical yield surfaces of the crushable foam formulations in the von Mises-pressure stress plane accurately characterise the plastic behaviour of trabecular bone. Results reveal that the hydrostatic yield stress is equal to the uniaxial yield stress for trabecular bone, demonstrating the importance of accurate characterisation and simulation of the pressure dependent plasticity. It is also demonstrated in this study that a commercially available trabecular bone analogue material, cellular rigid polyurethane foam, exhibits similar pressure dependent yield behaviour, despite having a lower stiffness and strength than trabecular bone. This study provides a novel insight into the pressure dependent yield behaviour of trabecular bone, demonstrating the inadequacy of uniaxial testing alone. For the first time, crushable foam plasticity formulations are implemented for trabecular bone. The enhanced understanding of the inelastic behaviour of trabecular bone established in this study will allow for more realistic simulation

Heme compounds in dinosaur trabecular bone.

PubMed

Schweitzer, M H; Marshall, M; Carron, K; Bohle, D S; Busse, S C; Arnold, E V; Barnard, D; Horner, J R; Starkey, J R

1997-06-10

Six independent lines of evidence point to the existence of heme-containing compounds and/or hemoglobin breakdown products in extracts of trabecular tissues of the large theropod dinosaur Tyrannosaurus rex. These include signatures from nuclear magnetic resonance and electron spin resonance that indicate the presence of a paramagnetic compound consistent with heme. In addition, UV/visible spectroscopy and high performance liquid chromatography data are consistent with the Soret absorbance characteristic of this molecule. Resonance Raman profiles are also consistent with a modified heme structure. Finally, when dinosaurian tissues were extracted for protein fragments and were used to immunize rats, the resulting antisera reacted positively with purified avian and mammalian hemoglobins. The most parsimonious explanation of this evidence is the presence of blood-derived hemoglobin compounds preserved in the dinosaurian tissues.

Trabecular fracture zone might not be the higher strain region of the trabecular framework

NASA Astrophysics Data System (ADS)

Tassani, Simone; Pani, Martino; Noailly, Jerome; Gonzalez Ballester, Miguel Angel

2018-02-01

Trabecular bone fracture is a traumatic and localized event studied worldwide in order to predict it. During the years researchers focussed over the mechanical characterization of the trabecular tissue to understand its mechanics. Several studies pointed out the very local nature of the trabecular failure, finally identifying the fracture zone with the aim to study it separately. The complexity of the three-dimensional trabecular framework and the local nature of the fracture event do not allow the direct evaluation of a single trabecula’s behaviour within its natural environment. For this reason, micro-Finite Element Modelling have been seen as the best way to investigate this biomechanical issue. Mechanical strain analysis is adopted in the literature for the identification of micro fracture using criteria based on principal strains. However, it was never verified if the fracture zone is actually the zone where principal strains are concentrated. Here we show how the maximum strain of the tissue might not be directly correlated to the fracture. In the present work a previously validated technique was used to identify the fracture zone of 10 trabecular specimen mechanically tested in compression and scanned in micro-CT before and after the mechanical test. Before-compression datasets were used to develop 10 micro-FE models were the same boundary conditions of the mechanical test were reproduced. Our results show how the known linear behaviour of the trabecular framework might not be directly related to the development of the fracture suggesting other non-linear phenomenon, like buckling or micro-damage, as actual cause of the traumatic event. This result might have several implications both in micro-modelling and in clinical applications for the study of fracture related pathology, like osteoporosis.

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

PubMed

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

2009-12-01

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

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

PubMed Central

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

2009-01-01

Disuse typically causes an imbalance in bone formation and bone resorption, leading to losses of cortical and trabecular bone. In contrast, bears maintain balanced intracortical remodeling and prevent cortical bone loss during disuse (hibernation). Trabecular bone, however, is more detrimentally affected than cortical bone in other animal models of disuse. Here we investigated the effects of hibernation on bone remodeling, architectural properties, and mineral density of grizzly bear (Ursus arctos horribilis) and black bear (Ursus americanus) trabecular bone in several skeletal locations. There were no differences in bone volume fraction or tissue mineral density between hibernating and active bears or between pre- and post-hibernation bears in the ilium, distal femur, or calcaneus. Though indices of cellular activity level (mineral apposition rate, osteoid thickness) decreased, trabecular bone resorption and formation indices remained balanced in hibernating grizzly bears. These data suggest that bears prevent bone loss during disuse by maintaining a balance between bone formation and bone resorption, which consequently preserves bone structure and strength. Further investigation of bone metabolism in hibernating bears may lead to the translation of mechanisms preventing disuse induced bone loss in bears into novel treatments for osteoporosis. PMID:19703606

Biomechanics and Mechanobiology of Trabecular Bone: A Review

PubMed Central

Oftadeh, Ramin; Perez-Viloria, Miguel; Villa-Camacho, Juan C.; Vaziri, Ashkan; Nazarian, Ara

2015-01-01

Trabecular bone is a highly porous, heterogeneous, and anisotropic material which can be found at the epiphyses of long bones and in the vertebral bodies. Studying the mechanical properties of trabecular bone is important, since trabecular bone is the main load bearing bone in vertebral bodies and also transfers the load from joints to the compact bone of the cortex of long bones. This review article highlights the high dependency of the mechanical properties of trabecular bone on species, age, anatomic site, loading direction, and size of the sample under consideration. In recent years, high resolution micro finite element methods have been extensively used to specifically address the mechanical properties of the trabecular bone and provide unique tools to interpret and model the mechanical testing experiments. The aims of the current work are to first review the mechanobiology of trabecular bone and then present classical and new approaches for modeling and analyzing the trabecular bone microstructure and macrostructure and corresponding mechanical properties such as elastic properties and strength. PMID:25412137

Primary Hyperparathyroidism is Associated with Abnormal Cortical and Trabecular Microstructure and Reduced Bone Stiffness in Postmenopausal Women

PubMed Central

Stein, Emily M; Silva, Barbara C; Boutroy, Stephanie; Zhou, Bin; Wang, Ji; Udesky, Julia; Zhang, Chiyuan; McMahon, Donald J; Romano, Megan; Dworakowski, Elzbieta; Costa, Aline G.; Cusano, Natalie; Irani, Dinaz; Cremers, Serge; Shane, Elizabeth; Guo, X Edward; Bilezikian, John P

2013-01-01

Typically, in the milder form of primary hyperparathyroidism (PHPT), seen in most countries now, bone density by DXA and detailed analyses of iliac crest bone biopsies by histomorphometry and µCT show detrimental effects in cortical bone, whereas the trabecular site (lumbar spine by DXA) and the trabecular compartment (by bone biopsy) appear to be relatively well preserved. Despite these findings, fracture risk at both vertebral and non-vertebral sites is increased in PHPT. Emerging technologies, such as high-resolution peripheral quantitative computed tomography (HRpQCT), may provide additional insight into microstructural features at sites such as the forearm and tibia that have heretofore not been easily accessible. Using HRpQCT, we determined cortical and trabecular microstructure at the radius and tibia in 51 postmenopausal women with PHPT and 120 controls. Individual trabecula segmentation (ITS) and micro finite element (µFE) analyses of the HRpQCT images were also performed to further understand how the abnormalities seen by HRpQCT might translate into effects on bone strength. Women with PHPT showed, at both sites, decreased volumetric densities at trabecular and cortical compartments, thinner cortices, and more widely spaced and heterogeneously distributed trabeculae. At the radius, trabeculae were thinner and fewer in PHPT. The radius was affected to a greater extent in the trabecular compartment than the tibia. ITS analyses revealed, at both sites, that plate-like trabeculae were depleted, with a resultant reduction in the plate/rod ratio. Microarchitectural abnormalities were evident by decreased plate-rod and plate-plate junctions at the radius and tibia, and rod-rod junctions at the radius. These trabecular and cortical abnormalities resulted in decreased whole bone stiffness and trabecular stiffness. These results provide evidence that in PHPT, microstructural abnormalities are pervasive and not limited to the cortical compartment. They may help to

Electrical stimulation at the dorsal root ganglion preserves trabecular bone mass and microarchitecture of the tibia in hindlimb-unloaded rats.

PubMed

Lau, Y-C; Qian, X; Po, K-T; Li, L-M; Guo, X

2015-02-01

This study seeks to investigate the effect of electrical stimulation (ES) at dorsal root ganglion (DRG) on disuse bone loss in a rat model. Hindlimb unloading for 14 days resulted in significant bone loss in rat tibia while rats with ES at DRG showed a significant reduced bone loss Mechanical unloading induces osteoporosis in both human and animals. Previous studies demonstrated that electrical stimulation (ES) to dorsal root ganglion (DRG) could trigger secretion of calcitonin gene-related peptide (CGRP) which plays an important role in bone modeling and remodeling. This study seeks to investigate the effect of ES to DRG on disuse bone loss in a rat model. Twenty-four rats were randomly assigned in three experimental groups: cage control (CC), hindlimb unloading (HU), and hindlimb unloading with ES (HUES). ES was applied via implantable micro-electrical stimulators (IMES) to right DRGs at vertebral levels L4-L6 in HUES group. Hindlimb unloading for 14 days resulted in 25.9% decrease in total bone mineral content (BMC), 29.2% decrease in trabecular BMD and trabecular microarchitecture and connectivity were significantly deteriorated in the proximal tibia metaphysis in HU group, while rats with ES at DRG showed significant reduced bone loss that there was 3.8% increase in total BMC, 2.3% decrease in trabecular BMD, and significant improvement in trabecular microarchitecture. There was a concurrent enhancement of expression of CGRP in stimulated DRGs. The results confirm the effect of ES at DRG on enhancing CGRP expression and suggest potential applications of IMES for the prevention and treatment of disuse bone loss.

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

PubMed Central

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

2017-01-01

Black women have lower fracture risk compared with white women, which may be partly explained by improved volumetric bone mineral density (vBMD) and bone microarchitecture primarily within the cortical bone compartment. To determine if there are differences in trabecular microstructure, connectivity, and alignment according to race/ethnicity, we performed individual trabecular segmentation (ITS) analyses on high-resolution peripheral quantitative computed tomography (HR-pQCT) scans of the distal radius and tibia in 273 peri- and postmenopausal black (n = 100) and white (n = 173) women participating in the Study of Women’s Health Across the Nation in Boston. Unadjusted analyses showed that black women had greater trabecular plate volume fraction, plate thickness, plate number density, and plate surface area along with greater axial alignment of trabeculae, whereas white women had greater trabecular rod tissue fraction (p < 0.05 for all). Adjustment for clinical covariates augmented these race/ethnicity-related differences in plates and rods, such that white women had greater trabecular rod number density and rod-rod connectivity, whereas black women continued to have superior plate structural characteristics and axial alignment (p < 0.05 for all). These differences remained significant after adjustment for hip BMD and trabecular vBMD. In conclusion, black women had more plate-like trabecular morphology and higher axial alignment of trabeculae, whereas white women had more rod-like trabeculae. These differences may contribute to the improved bone strength and lower fracture risk observed in black women. PMID:27958659

Trabecular bone deficits among Vietnamese immigrants.

PubMed

Melton, L J; Marquez, M A; McCready, L K; Achenbach, S J; Riggs, B L; Amin, S; Khosla, S

2011-05-01

Compared to white women, lower areal bone mineral density (aBMD) in middle-aged Vietnamese immigrants is due to reduced trabecular volumetric bone mineral density (vBMD), which in turn is associated with greater trabecular separation along with lower estrogen levels. The epidemiology of osteoporosis in Asian populations is still poorly known, but we previously found a deficit in lumbar spine aBMD among postmenopausal Southeast Asian women, compared to white women, that persisted after correction for bone size. This issue was revisited using more sophisticated imaging techniques. Twenty Vietnamese immigrants (age, 44-79 years) were compared to 162 same-aged white women with respect to aBMD at the hip, spine and wrist, vBMD at the hip and spine by quantitative computed tomography and vBMD and bone microstructure at the ultradistal radius by high-resolution pQCT. Bone turnover and sex steroid levels were assessed in a subset (20 Vietnamese and 40 white women). The aBMD was lower at all sites among the Vietnamese women, but femoral neck vBMD did not differ from middle-aged white women. Significant differences in lumbar spine and ultradistal radius vBMD in the Vietnamese immigrants were due to lower trabecular vBMD, which was associated with increased trabecular separation. Bone resorption was elevated and bone formation depressed among the Vietnamese immigrants, although trends were not statistically significant. Serum estradiol was positively associated with trabecular vBMD in the Vietnamese women, but their estrogen levels were dramatically lower compared to white women. Although reported discrepancies in aBMD among Asian women are mainly an artifact of smaller bone size, we identified a specific deficit in the trabecular bone among a sample of Vietnamese immigrants that may be related to low estrogen levels and which needs further study.

Trabecular bone deficits among Vietnamese immigrants

PubMed Central

Marquez, M. A.; McCready, L. K.; Achenbach, S. J.; Riggs, B. L.; Amin, S.; Khosla, S.

2011-01-01

Summary Compared to white women, lower areal bone mineral density (aBMD) in middle-aged Vietnamese immigrants is due to reduced trabecular volumetric bone mineral density (vBMD), which in turn is associated with greater trabecular separation along with lower estrogen levels. Introduction The epidemiology of osteoporosis in Asian populations is still poorly known, but we previously found a deficit in lumbar spine aBMD among postmenopausal Southeast Asian women, compared to white women, that persisted after correction for bone size. This issue was revisited using more sophisticated imaging techniques. Methods Twenty Vietnamese immigrants (age, 44–79 years) were compared to 162 same-aged white women with respect to aBMD at the hip, spine and wrist, vBMD at the hip and spine by quantitative computed tomography and vBMD and bone microstructure at the ultradistal radius by high-resolution pQCT. Bone turnover and sex steroid levels were assessed in a subset (20 Vietnamese and 40 white women). Results The aBMD was lower at all sites among the Vietnamese women, but femoral neck vBMD did not differ from middle-aged white women. Significant differences in lumbar spine and ultradistal radius vBMD in the Vietnamese immigrants were due to lower trabecular vBMD, which was associated with increased trabecular separation. Bone resorption was elevated and bone formation depressed among the Vietnamese immigrants, although trends were not statistically significant. Serum estradiol was positively associated with trabecular vBMD in the Vietnamese women, but their estrogen levels were dramatically lower compared to white women. Conclusions Although reported discrepancies in aBMD among Asian women are mainly an artifact of smaller bone size, we identified a specific deficit in the trabecular bone among a sample of Vietnamese immigrants that may be related to low estrogen levels and which needs further study. PMID:20658128

Nonlinear viscoelastic characterization of bovine trabecular bone.

PubMed

Manda, Krishnagoud; Wallace, Robert J; Xie, Shuqiao; Levrero-Florencio, Francesc; Pankaj, Pankaj

2017-02-01

The time-independent elastic properties of trabecular bone have been extensively investigated, and several stiffness-density relations have been proposed. Although it is recognized that trabecular bone exhibits time-dependent mechanical behaviour, a property of viscoelastic materials, the characterization of this behaviour has received limited attention. The objective of the present study was to investigate the time-dependent behaviour of bovine trabecular bone through a series of compressive creep-recovery experiments and to identify its nonlinear constitutive viscoelastic material parameters. Uniaxial compressive creep and recovery experiments at multiple loads were performed on cylindrical bovine trabecular bone samples ([Formula: see text]). Creep response was found to be significant and always comprised of recoverable and irrecoverable strains, even at low stress/strain levels. This response was also found to vary nonlinearly with applied stress. A systematic methodology was developed to separate recoverable (nonlinear viscoelastic) and irrecoverable (permanent) strains from the total experimental strain response. We found that Schapery's nonlinear viscoelastic constitutive model describes the viscoelastic response of the trabecular bone, and parameters associated with this model were estimated from the multiple load creep-recovery (MLCR) experiments. Nonlinear viscoelastic recovery compliance was found to have a decreasing and then increasing trend with increasing stress level, indicating possible stiffening and softening behaviour of trabecular bone due to creep. The obtained parameters from MLCR tests, expressed as second-order polynomial functions of stress, showed a similar trend for all the samples, and also demonstrate stiffening-softening behaviour with increasing stress.

An Quantitative Analysis Method Of Trabecular Pattern In A Bone

NASA Astrophysics Data System (ADS)

Idesawa, Masanor; Yatagai, Toyohiko

1982-11-01

Orientation and density of trabecular pattern observed in a bone is closely related to its mechanical properties and deseases of a bone are appeared as changes of orientation and/or density distrbution of its trabecular patterns. They have been treated from a qualitative point of view so far because quantitative analysis method has not be established. In this paper, the authors proposed and investigated some quantitative analysis methods of density and orientation of trabecular patterns observed in a bone. These methods can give an index for evaluating orientation of trabecular pattern quantitatively and have been applied to analyze trabecular pattern observed in a head of femur and their availabilities are confirmed. Key Words: Index of pattern orientation, Trabecular pattern, Pattern density, Quantitative analysis

Trabecular architecture in the sciuromorph femoral head: allometry and functional adaptation.

PubMed

Mielke, Maja; Wölfer, Jan; Arnold, Patrick; van Heteren, Anneke H; Amson, Eli; Nyakatura, John A

2018-01-01

Sciuromorpha (squirrels and close relatives) are diverse in terms of body size and locomotor behavior. Individual species are specialized to perform climbing, gliding or digging behavior, the latter being the result of multiple independent evolutionary acquisitions. Each lifestyle involves characteristic loading patterns acting on the bones of sciuromorphs. Trabecular bone, as part of the bone inner structure, adapts to such loading patterns. This network of thin bony struts is subject to bone modeling, and therefore reflects habitual loading throughout lifetime. The present study investigates the effect of body size and lifestyle on trabecular structure in Sciuromorpha. Based upon high-resolution computed tomography scans, the femoral head 3D inner microstructure of 69 sciuromorph species was analyzed. Species were assigned to one of the following lifestyle categories: arboreal, aerial, fossorial and semifossorial. A cubic volume of interest was selected in the center of each femoral head and analyzed by extraction of various parameters that characterize trabecular architecture (degree of anisotropy, bone volume fraction, connectivity density, trabecular thickness, trabecular separation, bone surface density and main trabecular orientation). Our analysis included evaluation of the allometric signals and lifestyle-related adaptation in the trabecular parameters. We show that bone surface density, bone volume fraction, and connectivity density are subject to positive allometry, and degree of anisotropy, trabecular thickness, and trabecular separation to negative allometry. The parameters connectivity density, bone surface density, trabecular thickness, and trabecular separation show functional signals which are related to locomotor behavior. Aerial species are distinguished from fossorial ones by a higher trabecular thickness, lower connectivity density and lower bone surface density. Arboreal species are distinguished from semifossorial ones by a higher trabecular

Inter-trabecular angle: A parameter of trabecular bone architecture in the human proximal femur that reveals underlying topological motifs.

PubMed

Reznikov, Natalie; Chase, Hila; Ben Zvi, Yehonatan; Tarle, Victoria; Singer, Matthew; Brumfeld, Vlad; Shahar, Ron; Weiner, Steve

2016-10-15

Trabecular bone is an intricate 3D network of struts and plates. Although the structure-function relations in trabecular bone have been studied since the time of Julius Wolff, controversy still exists regarding the architectural parameters responsible for its stability and resilience. We present a parameter that measures the angle between two connected trabeculae - the Inter-Trabecular Angle (ITA). We studied the ITA values derived from μCT scans of different regions of the proximal femora of 5 individuals of different age and sex. We show that the ITA angle distribution of nodes with 3 connecting trabeculae has a mean close to 120°, nodes with 4 connecting trabeculae has a mean close to 109° and nodes of higher connectivity have mean ITA values around 100°. This tendency to spread the ITAs around geometrically symmetrical motifs is highly conserved. The implication is that the ITAs are optimized such that the smallest amount of material spans the maximal 3D volume, and possibly by so doing trabecular bone might be better adapted to multidirectional loading. We also draw a parallel between trabecular bone and tensegrity structures - where lightweight, resilient and stable tetrahedron-based shapes contribute to strain redistribution amongst all the elements and to collective impact dampening. The Inter-Trabecular Angle (ITA) is a new topological parameter of trabecular bone. The ITA characterizes the way trabeculae connect with each other at nodes, regardless of their thickness and shape. The mean ITA value of nodes with 3 trabeculae is close to 120°, of nodes with 4 trabeculae is just below 109°, and the mean ITA of nodes with 5 and more trabeculae is around 100°. Thus the connections of trabeculae trend towards adopting symmetrical shapes. This implies that trabeculae can maximally span 3D space using the minimal amount of material. We draw a parallel between this motif and the concept of tensegrity - an engineering premise to which many living creatures

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

NASA Astrophysics Data System (ADS)

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

2016-10-01

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

Zoledronate, ibandronate and clodronate enhance osteoblast differentiation in a dose dependent manner--a quantitative in vitro gene expression analysis of Dlx5, Runx2, OCN, MSX1 and MSX2.

PubMed

Koch, Felix Peter; Merkel, Christina; Al-Nawas, Bilal; Smeets, Ralf; Ziebart, Thomas; Walter, Christian; Wagner, Wilfried

2011-12-01

Bisphosphonates are widely used in the clinical treatment of bone diseases with increased bone resorption. In terms of side effects, they are known to be associated with osteonecrosis of the jaw (BONJ). There are two groups of bisphosphonates: the nitrogen-containing bisphosphonates, e.g. zoledronate and ibandronate, and the non-nitrogen-containing bisphosphonates, e.g. clodronate. Their impact on bone metabolism seems to differ. The objective of this study was to compare the osteogenic differentiation potency of these two pharmacologic groups. Human osteoblasts were stimulated with zoledronate and ibandronate at concentrations of 5×10(-5) M, 5×10(-6) M and 5×10(-7) M over the experimental periods of 1, 2, 5, 10 and 14 days. Clodronate was applied with concentrations of 5×10(-3), 5×10(-5) M and 5×10(-6) M. At each time point, the cells were dissolved, the mRNA extracted, and the gene expression level of the osteoblast specific differentiation markers of the homeobox transcription factors MSX1 and MSX2, the distal-less homeobox 5 (Dlx5), the Runt-related transcription factor 2 (Runx2/CBF1a) and osteocalcin (OCN) were quantified by Real-Time PCR. The gene expression was compared to an unstimulated osteoblast cell culture as control. The results showed a significant difference between the nitrogen-containing and the non-nitrogen-containing bisphosphonates. Zoledronate and ibandronate at concentrations of 5×10(-5) M enhanced the gene expression of all differentiation markers by several hundred folds compared to unstimulated control after 10 days, whereas clodronate had less influence on gene expression, even at higher concentrations of 5×10(-3) M. Lower concentrations of zoledronate and ibandronate, however, led to a decreased gene expression. These data confirm the results of other studies which have shown the osteogenic stimulus on osteoblasts in a dose dependent manner. The nitrogen-containing bisphosphonates appear to enhance bone density by stimulation of

Trabecular bone in the calcaneus of runners

PubMed Central

Holt, Brigitte; Troy, Karen; Hamill, Joseph

2017-01-01

Trabecular bone of the human calcaneus is subjected to extreme repetitive forces during endurance running and should adapt in response to this strain. To assess possible bone functional adaptation in the posterior region of the calcaneus, we recruited forefoot-striking runners (n = 6), rearfoot-striking runners (n = 6), and non-runners (n = 6), all males aged 20–41 for this institutionally approved study. Foot strike pattern was confirmed for each runner using a motion capture system. We obtained high resolution peripheral computed tomography scans of the posterior calcaneus for both runners and non-runners. No statistically significant differences were found between runners and nonrunners or forefoot strikers and rearfoot strikers. Mean trabecular thickness and mineral density were greatest in forefoot runners with strong effect sizes (<0.80). Trabecular thickness was positively correlated with weekly running distance (r2 = 0.417, p<0.05) and years running (r2 = 0.339, p<0.05) and negatively correlated with age at onset of running (r2 = 0.515, p<0.01) Trabecular thickness, mineral density and bone volume ratio of nonrunners were highly correlated with body mass (r2 = 0.824, p<0.05) and nonrunners were significantly heavier than runners (p<0.05). Adjusting for body mass revealed significantly thicker trabeculae in the posterior calcaneus of forefoot strikers, likely an artifact of greater running volume and earlier onset of running in this subgroup; thus, individuals with the greatest summative loading stimulus had, after body mass adjustment, the thickest trabeculae. Further study with larger sample sizes is necessary to elucidate the role of footstrike on calcaneal trabecular structure. To our knowledge, intraspecific body mass correlations with measures of trabecular robusticity have not been reported elsewhere. We hypothesize that early adoption of running and years of sustained moderate volume running stimulate bone modeling in trabeculae of the posterior

Trabecular bone in the calcaneus of runners.

PubMed

Best, Andrew; Holt, Brigitte; Troy, Karen; Hamill, Joseph

2017-01-01

Trabecular bone of the human calcaneus is subjected to extreme repetitive forces during endurance running and should adapt in response to this strain. To assess possible bone functional adaptation in the posterior region of the calcaneus, we recruited forefoot-striking runners (n = 6), rearfoot-striking runners (n = 6), and non-runners (n = 6), all males aged 20-41 for this institutionally approved study. Foot strike pattern was confirmed for each runner using a motion capture system. We obtained high resolution peripheral computed tomography scans of the posterior calcaneus for both runners and non-runners. No statistically significant differences were found between runners and nonrunners or forefoot strikers and rearfoot strikers. Mean trabecular thickness and mineral density were greatest in forefoot runners with strong effect sizes (<0.80). Trabecular thickness was positively correlated with weekly running distance (r2 = 0.417, p<0.05) and years running (r2 = 0.339, p<0.05) and negatively correlated with age at onset of running (r2 = 0.515, p<0.01) Trabecular thickness, mineral density and bone volume ratio of nonrunners were highly correlated with body mass (r2 = 0.824, p<0.05) and nonrunners were significantly heavier than runners (p<0.05). Adjusting for body mass revealed significantly thicker trabeculae in the posterior calcaneus of forefoot strikers, likely an artifact of greater running volume and earlier onset of running in this subgroup; thus, individuals with the greatest summative loading stimulus had, after body mass adjustment, the thickest trabeculae. Further study with larger sample sizes is necessary to elucidate the role of footstrike on calcaneal trabecular structure. To our knowledge, intraspecific body mass correlations with measures of trabecular robusticity have not been reported elsewhere. We hypothesize that early adoption of running and years of sustained moderate volume running stimulate bone modeling in trabeculae of the posterior

3D Architecture of Trabecular Bone in the Pig Mandible and Femur: Inter-Trabecular Angle Distributions.

NASA Astrophysics Data System (ADS)

Ben-Zvi, Yehonatan; Reznikov, Natalie; Shahar, Ron; Weiner, Steve

2017-09-01

Cancellous bone is an intricate network of interconnected trabeculae, to which analysis of network topology can be applied. The inter-trabecular angle (ITA) analysis - an analysis of network topological parameters and regularity of network-forming nodes, was previously carried out on human proximal femora and showed that trabecular bone follows two main principles: sparsity of the network connectedness (prevalence of nodes with low connectivity in the network) and maximal space spanning (angular offset of connected elements is maximal for their number and approximates the values of geometrically symmetric shapes). These observations suggest that 3D organization of trabecular bone, irrespective of size and shape of individual elements, reflects a tradeoff between minimal metabolic cost of maintenance and maximal network stability under conditions of multidirectional loading. In this study we validate the ITA application using additional 3D structures (cork and 3D-printed metal lattices), analyze the ITA parameters in porcine proximal femora and mandibles and carry out a spatial analysis of the most common node type in the porcine mandibular condyle. The validation shows that the ITA application reliably detects designed or evolved topological parameters. The ITA parameters of porcine trabecular bones are similar to those of human bones. We demonstrate functional adaptation in the pig mandibular condyle by showing that the planar nodes with 3 edges are preferentially aligned in relation to the muscle forces that are applied to the condyle. We conclude that the ITA topological parameters are remarkable conserved, but locally do adapt to applied stresses.

Recent origin of low trabecular bone density in modern humans

PubMed Central

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

2015-01-01

Humans are unique, compared with our closest living relatives (chimpanzees) and early fossil hominins, in having an enlarged body size and lower limb joint surfaces in combination with a relatively gracile skeleton (i.e., lower bone mass for our body size). Some analyses have observed that in at least a few anatomical regions modern humans today appear to have relatively low trabecular density, but little is known about how that density varies throughout the human skeleton and across species or how and when the present trabecular patterns emerged over the course of human evolution. Here, we test the hypotheses that (i) recent modern humans have low trabecular density throughout the upper and lower limbs compared with other primate taxa and (ii) the reduction in trabecular density first occurred in early Homo erectus, consistent with the shift toward a modern human locomotor anatomy, or more recently in concert with diaphyseal gracilization in Holocene humans. We used peripheral quantitative CT and microtomography to measure trabecular bone of limb epiphyses (long bone articular ends) in modern humans and chimpanzees and in fossil hominins attributed to Australopithecus africanus, Paranthropus robustus/early Homo from Swartkrans, Homo neanderthalensis, and early Homo sapiens. Results show that only recent modern humans have low trabecular density throughout the limb joints. Extinct hominins, including pre-Holocene Homo sapiens, retain the high levels seen in nonhuman primates. Thus, the low trabecular density of the recent modern human skeleton evolved late in our evolutionary history, potentially resulting from increased sedentism and reliance on technological and cultural innovations. PMID:25535354

Recent origin of low trabecular bone density in modern humans.

PubMed

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

2015-01-13

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

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

PubMed

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.

Study of trabecular bone microstructure using spatial autocorrelation analysis

NASA Astrophysics Data System (ADS)

Wald, Michael J.; Vasilic, Branimir; Saha, Punam K.; Wehrli, Felix W.

2005-04-01

The spatial autocorrelation analysis method represents a powerful, new approach to quantitative characterization of structurally quasi-periodic anisotropic materials such as trabecular bone (TB). The method is applicable to grayscale images and thus does not require any preprocessing, such as segmentation which is difficult to achieve in the limited resolution regime of in vivo imaging. The 3D autocorrelation function (ACF) can be efficiently calculated using the Fourier transform. The resulting trabecular thickness and spacing measurements are robust to the presence of noise and produce values within the expected range as determined by other methods from μCT and μMRI datasets. TB features found from the ACF are shown to correlate well with those determined by the Fuzzy Distance transform (FDT) in the transverse plane, i.e. the plane orthogonal to bone"s major axis. The method is further shown to be applicable to in-vivo μMRI data. Using the ACF, we examine data acquired in a previous study aimed at evaluating the structural implications of male hypogonadism characterized by testosterone deficiency and reduced bone mass. Specifically, we consider the hypothesis that eugonadal and hypogonadal men differ in the anisotropy of their trabecular networks. The analysis indicates a significant difference in trabecular bone thickness and longitudinal spacing between the control group and the testosterone deficient group. We conclude that spatial autocorrelation analysis is able to characterize the 3D structure and anisotropy of trabecular bone and provides new insight into the structural changes associated with osteoporotic trabecular bone loss.

The effects of the Er:YAG laser on trabecular bone micro-architecture: Comparison with conventional dental drilling by micro-computed tomographic and histological techniques

PubMed Central

Zeitouni, Jihad; Clough, Bret; Zeitouni, Suzanne; Saleem, Mohammed; Al Aisami, Kenan; Gregory, Carl

2017-01-01

Background: The use of lasers has become increasingly common in the field of medicine and dentistry, and there is a growing need for a deeper understanding of the procedure and its effects on tissue. The aim of this study was to compare the erbium-doped yttrium aluminium garnet (Er:YAG) laser and conventional drilling techniques, by observing the effects on trabecular bone microarchitecture and the extent of thermal and mechanical damage. Methods: Ovine femoral heads were employed to mimic maxillofacial trabecular bone, and cylindrical osteotomies were generated to mimic implant bed preparation. Various laser parameters were tested, as well as a conventional dental drilling technique. The specimens were then subjected to micro-computed tomographic (μCT) histomorphometic analysis and histology. Results: Herein, we demonstrate that mCT measurements of trabecular porosity provide quantitative evidence that laser-mediated cutting preserves the trabecular architecture and reduces thermal and mechanical damage at the margins of the cut. We confirmed these observations with histological studies. In contrast with laser-mediated cutting, conventional drilling resulted in trabecular collapse, reduction of porosity at the margin of the cut and histological signs of thermal damage. Conclusions: This study has demonstrated, for the first time, that mCT and quantification of porosity at the margin of the cut provides a quantitative insight into damage caused by bone cutting techniques. We further show that with laser-mediated cutting, the marrow remains exposed to the margins of the cut, facilitating cellular infiltration and likely accelerating healing. However, with drilling, trabecular collapse and thermal damage is likely to delay healing by restricting the passage of cells to the site of injury and causing localized cell death. PMID:29416849

Determinants of Microdamage in Elderly Human Vertebral Trabecular Bone

PubMed Central

Follet, Hélène; Farlay, Delphine; Bala, Yohann; Viguet-Carrin, Stéphanie; Gineyts, Evelyne; Burt-Pichat, Brigitte; Wegrzyn, Julien; Delmas, Pierre; Boivin, Georges; Chapurlat, Roland

2013-01-01

Previous studies have shown that microdamage accumulates in bone as a result of physiological loading and occurs naturally in human trabecular bone. The purpose of this study was to determine the factors associated with pre-existing microdamage in human vertebral trabecular bone, namely age, architecture, hardness, mineral and organic matrix. Trabecular bone cores were collected from human L2 vertebrae (n = 53) from donors 54–95 years of age (22 men and 30 women, 1 unknown) and previous cited parameters were evaluated. Collagen cross-link content (PYD, DPD, PEN and % of collagen) was measured on surrounding trabecular bone. We found that determinants of microdamage were mostly the age of donors, architecture, mineral characteristics and mature enzymatic cross-links. Moreover, linear microcracks were mostly associated with the bone matrix characteristics whereas diffuse damage was associated with architecture. We conclude that linear and diffuse types of microdamage seemed to have different determinants, with age being critical for both types. PMID:23457465

Aqueous Humor Rapidly Stimulates Myocilin Secretion from Human Trabecular Meshwork Cells

PubMed Central

Resch, Zachary T.; Hann, Cheryl R.; Cook, Kimberly A.; Fautsch, Michael P.

2010-01-01

Myocilin, a protein associated with the development of glaucoma, is expressed in most eye tissues with highest expression observed in trabecular meshwork cells. In culture, primary human trabecular meshwork cells incubated in 10% fetal bovine serum have reduced myocilin expression compared to in vivo, but incubation in human aqueous humor, their normal in vivo nutrient source, restores myocilin expression to near in vivo levels. To investigate the mechanism by which human aqueous humor stimulates myocilin accumulation in conditioned media from normal human trabecular meshwork cells, three independent trabecular meshwork cell lines were cultured in Dulbecco’s Modified Eagle’s Medium (DMEM) containing various supplements: fetal bovine serum (10%), human serum (0.2%), porcine aqueous humor (50%), bovine serum albumin (0.1%), dexamethasone (10−7 M), human aqueous humor (50%) or heat-inactivated human aqueous humor (50%). Conditioned media from cultured primary trabecular meshwork cells following incubation in human aqueous humor showed significant accumulation of myocilin in a time- (15 minutes) and dose-dependent manner (half maximal effective concentration ~ 30%) while intracellular myocilin levels decreased. Minimal myocilin accumulation was observed in conditioned media isolated from trabecular meshwork cells cultured in DMEM containing fetal bovine or human serum, bovine serum albumin, porcine aqueous humor, dexamethasone or DMEM alone. Heat inactivation of human aqueous humor nearly eliminated human aqueous humor-stimulated myocilin secretion. Inhibitors of new protein synthesis, gene transcription, the endoplasmic reticulum/Golgi system and endocytic/exocytic secretory pathways failed to inhibit human aqueous humor-stimulated myocilin secretion. Using immunolabeling and transmission electron microscopy, myocilin was found associated with 70–90 nm vesicle-like structures within the cytoplasm of human aqueous humor treated trabecular meshwork cells. These

Automated trabecular bone histomorphometry

NASA Technical Reports Server (NTRS)

Polig, E.; Jee, W. S. S.

1985-01-01

The toxicity of alpha-emitting bone-seeking radionuclides and the relationship between bone tumor incidence and the local dosimetry of radionuclides in bone are investigated. The microdistributions of alpha-emitting radionuclides in the trabecular bone from the proximal humerus, distal humerus, proximal ulna, proximal femur, and distal femur of six young adult beagles injected with Am-241 (three with 2.8 micro-Ci/kg and three with 0.9 micro-Ci/kg) are estimated using a computer-controlled microscope photometer system; the components of the University of Utah Optical Track Scanner are described. The morphometric parameters for the beagles are calculated and analyzed. It is observed that the beagles injected with 0.9 micro-Ci of Am-241/kg showed an increase in the percentage of bone and trabecular bone thickness, and a reduction in the width of the bone marrow space and surface/volume ratio. The data reveal that radiation damage causes abnormal bone structure.

Methodological considerations for analyzing trabecular architecture: an example from the primate hand.

PubMed

Kivell, Tracy L; Skinner, Matthew M; Lazenby, Richard; Hublin, Jean-Jacques

2011-02-01

Micro-computed tomographic analyses of trabecular bone architecture have been used to clarify the link between positional behavior and skeletal anatomy in primates. However, there are methodological decisions associated with quantifying and comparing trabecular anatomy across taxa that vary greatly in body size and morphology that can affect characterizations of trabecular architecture, such as choice of the volume of interest (VOI) size and location. The potential effects of these decisions may be amplified in small, irregular-shaped bones of the hands and feet that have more complex external morphology and more heterogeneous trabecular structure compared to, for example, the spherical epiphysis of the femoral head. In this study we investigate the effects of changes in VOI size and location on standard trabecular parameters in two bones of the hand, the capitate and third metacarpal, in a diverse sample of nonhuman primates that vary greatly in morphology, body mass and positional behavior. Results demonstrate that changes in VOI location and, to a lesser extent, changes in VOI size had a dramatic affect on many trabecular parameters, especially trabecular connectivity and structure (rods vs. plates), degree of anisotropy, and the primary orientation of the trabeculae. Although previous research has shown that some trabecular parameters are susceptible to slight variations in methodology (e.g. VOI location, scan resolution), this study provides a quantification of these effects in hand bones of a diverse sample of primates. An a priori understanding of the inherent biases created by the choice of VOI size and particularly location is critical to robust trabecular analysis and functional interpretation, especially in small bones with complex arthroses. © 2010 The Authors. Journal of Anatomy © 2010 Anatomical Society of Great Britain and Ireland.

Ultrasonic wave propagation in trabecular bone predicted by the stratified model

NASA Technical Reports Server (NTRS)

Lin, W.; Qin, Y. X.; Rubin, C.

2001-01-01

The objective of this study was to investigate ultrasound propagation in trabecular bone by considering the wave reflection and transmission in a multilayered medium. The use of ultrasound to identify those at risk of osteoporosis is a promising diagnostic method providing a measure of bone mineral density (BMD). A stratified model was proposed to study the effect of transmission and reflection of ultrasound wave within the trabecular architecture on the relationship between ultrasound and BMD. The results demonstrated that ultrasound velocity in trabecular bone was highly correlated with the bone apparent density (r=0.97). Moreover, a consistent pattern of the frequency dependence of ultrasound attenuation coefficient has been observed between simulation using this model and experimental measurement of trabecular bone. The normalized broadband ultrasound attenuation (nBUA) derived from the simulation results revealed that nBUA was nonlinear with respect to trabecular porosity and BMD. The curve of the relationship between nBUA and BMD was parabolic in shape, and the peak magnitude of nBUA was observed at approximately 60% of bone porosity. These results agreed with the published experimental data and demonstrated that according to the stratified model, reflection and transmission were important factors in the ultrasonic propagation through the trabecular bone.

Ibandronate metal complexes: solution behavior and antiparasitic activity.

PubMed

Demoro, Bruno; Rostán, Santiago; Moncada, Mauricio; Li, Zhu-Hong; Docampo, Roberto; Olea Azar, Claudio; Maya, Juan Diego; Torres, Julia; Gambino, Dinorah; Otero, Lucía

2018-03-01

To face the high costs of developing new drugs, researchers in both industry and academy are looking for ways to repurpose old drugs for new uses. In this sense, bisphosphonates that are clinically used for bone diseases have been studied as agents against Trypanosoma cruzi, causative parasite of Chagas disease. In this work, the development of first row transition metal complexes (M = Co 2+ , Mn 2+ , Ni 2+ ) with the bisphosphonate ibandronate (iba, H 4 iba representing the neutral form) is presented. The in-solution behavior of the systems containing iba and the selected 3d metal ions was studied by potentiometry. Mononuclear complexes [M(H x iba)] (2-x)- (x = 0-3) and [M(Hiba) 2 ] 4- together with the formation of the neutral polynuclear species [M 2 iba] and [M 3 (Hiba) 2 ] were detected for all studied systems. In the solid state, complexes of the formula [M 3 (Hiba) 2 (H 2 O) 4 ]·6H 2 O were obtained and characterized. All obtained complexes, forming [M(Hiba)] - species under the conditions of the biological studies, were more active against the amastigote form of T. cruzi than the free iba, showing no toxicity in mammalian Vero cells. In addition, the same complexes were selective inhibitors of the parasitic farnesyl diphosphate synthase (FPPS) enzyme showing poor inhibition of the human one. However, the increase of the anti-T. cruzi activity upon coordination could not be explained neither through the inhibition of TcFPPS nor through the inhibition of TcSPPS (T. cruzi solanesyl-diphosphate synthase). The ability of the obtained metal complexes of catalyzing the generation of free radical species in the parasite could explain the observed anti-T. cruzi activity.

Kinetic characterization of the deproteinization of trabecular and cortical bovine femur bones.

PubMed

Castro-Ceseña, Ana B; Sánchez-Saavedra, M Pilar; Novitskaya, Ekaterina E; Chen, Po-Yu; Hirata, Gustavo A; McKittrick, Joanna

2013-12-01

The present study proposes an interpretation of the mechanism of bone deproteinization. Cortical and trabecular bovine femur bones were deproteinized using 6% NaOCl (37, 50, 60°C). The kinetic parameters (rate constant and activation energy) were calculated, and the surface area of each type of bone was considered. A statistical analysis of the rate constants shows that cortical bone deproteinizes at a lower rate than trabecular. The activation energy is higher for trabecular than cortical bone, and no significant differences are found in the protein concentration values for both bones. Therefore, although trabecular bone deproteinizes at a higher rate than cortical, trabecular bone requires more energy for the deproteinization reaction to take place. Considering that both types of bones are constituted by mineral, protein, and water; the present work shows that the individual inner matrix architecture of trabecular and cortical bones, along with characteristics such as the mineral concentration and its bonding with collagen fibers, may be the responsible factors that control protein depletion. © 2013.

The Effects of Partial Mechanical Loading and Ibandronate on Skeletal Tissues in the Adult Rat Hindquarter Suspension Model for Microgravity

NASA Technical Reports Server (NTRS)

Schultheis, Lester W.

1999-01-01

We report initial data from a suspended rat model that quantitatively relates chronic partial weightbearing to bone loss. Chronic partial weightbearing is our simulation of the effect of limited artificial gravity aboard spacecraft or reduced planetary gravity. Preliminary analysis of bone by PQCT, histomorphometry, mechanical testing and biochemistry suggest that chronic exposure to half of Earth gravity is insufficient to prevent severe bone loss. The effect of episodic full weightbearing activity (Earth Gravity) on rats otherwise at 50% weightbearing was also explored. This has similarity to treatment by an Earth G-rated centrifuge on a spacecraft that normally maintained artificial gravity at half of Earth G. Our preliminary evidence, using the above techniques to analyze bone, indicate that 2 hours daily of full weightbearing was insufficient to prevent the bone loss observed in 50% weightbearing animals. The effectiveness of partial weightbearing and episodic full weightbearing as potential countermeasures to bone loss in spaceflight was compared with treatment by ibandronate. Ibandronate, a long-acting potent bisphosphonate proved more effective in preventing bone loss and associated functionality based upon structure than our first efforts at mechanical countermeasures. The effectiveness of ibandronate was notable by each of the testing methods we used to study bone from gross structure and strength to tissue and biochemistry. These results appear to be independent of generalized systemic stress imposed by the suspension paradigm. Preliminary evidence does not suggest that blood levels of vitamin D were affected by our countermeasures. Despite the modest theraputic benefit of mechanical countermeasures of partial weightbearing and episodic full weightbearing, we know that some appropriate mechanical signal maintains bone mass in Earth gravity. Moreover, the only mechanism that correctly assigns bone mass and strength to oppose regionally specific force

Osteoarthritis alters the patellar bones subchondral trabecular architecture.

PubMed

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

2017-09-01

Following the principles of "morphology reveals biomechanics," the cartilage-osseous interface and the trabecular network show defined adaptation in response to physiological loading. In the case of a compromised relationship, the ability to support the load diminishes and the onset of osteoarthritis (OA) may arise. To describe and quantify the changes within the subchondral bone plate (SBP) and trabecular architecture, 10 human OA patellae were investigated by CT and micro-CT. The results are presented in comparison to a previously published dataset of 10 non-OA patellae which were evaluated in the same manner. The analyzed OA samples showed no distinctive mineralization pattern in regards to the physiological biomechanics, but a highly irregular disseminated distribution. In addition, no regularity in bone distribution and architecture across the trabecular network was found. We observed a decrease of material as the bone volume and trabecular thickness/number were significantly reduced. In comparison to non-OA samples, greatest differences for all parameters were found within the first mm of trabecular bone. The differences decreased toward the fifth mm in a logarithmic manner. The interpretation of the logarithmic relation leads to the conclusion that the main impact of OA on bony structures is located beneath the SBP and lessens with depth. In addition to the clear difference in material with approximately 12% less bone volume in the first mm in OA patellae, the architectural arrangement is more rod-like and isotropic, accounting for an architectural decrease in stability and support. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1982-1989, 2017. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

Genetic modification of human trabecular meshwork with lentiviral vectors.

PubMed

Loewen, N; Fautsch, M P; Peretz, M; Bahler, C K; Cameron, J D; Johnson, D H; Poeschla, E M

2001-11-20

Glaucoma, a group of optic neuropathies, is the leading cause of irreversible blindness. Neuronal apoptosis in glaucoma is primarily associated with high intraocular pressure caused by chronically impaired outflow of aqueous humor through the trabecular meshwork, a reticulum of mitotically inactive endothelial-like cells located in the angle of the anterior chamber. Anatomic, genetic, and expression profiling data suggest the possibility of using gene transfer to treat glaucomatous intraocular pressure dysregulation, but this approach will require stable genetic modification of the differentiated aqueous outflow tract. We injected transducing unit-normalized preparations of either of two lentiviral vectors or an oncoretroviral vector as a single bolus into the aqueous circulation of cultured human donor eyes, under perfusion conditions that mimicked natural anterior chamber flow and maintained viability ex vivo. Reporter gene expression was assessed in trabecular meshwork from 3 to 16 days after infusion of 1.0 x 10(8) transducing units of each vector. The oncoretroviral vector failed to transduce the trabecular meshwork. In contrast, feline immunodeficiency virus and human immunodeficiency virus vectors produced efficient, localized transduction of the trabecular meshwork in situ. The results demonstrate that lentiviral vectors permit efficient genetic modification of the human trabecular meshwork when delivered via the afferent aqueous circulation, a clinically accessible route. In addition, controlled comparisons in this study establish that feline and human immunodeficiency virus vectors are equivalently efficacious in delivering genes to this terminally differentiated human tissue.

Protection of trabecular bone in ovariectomized rats by turmeric (Curcuma longa L.) is dependent on extract composition.

PubMed

Wright, Laura E; Frye, Jennifer B; Timmermann, Barbara N; Funk, Janet L

2010-09-08

Extracts prepared from turmeric (Curcuma longa L., [Zingiberaceae]) containing bioactive phenolic curcuminoids were evaluated for bone-protective effects in a hypogonadal rat model of postmenopausal osteoporosis. Three-month female Sprague-Dawley rats were ovariectomized (OVX) and treated with a chemically complex turmeric fraction (41% curcuminoids by weight) or a curcuminoid-enriched turmeric fraction (94% curcuminoids by weight), both dosed at 60 mg/kg 3x per week, or vehicle alone. Effects of two months of treatment on OVX-induced bone loss were followed prospectively by serial assessment of bone mineral density (BMD) of the distal femur using dual-energy X-ray absorptiometry (DXA), while treatment effects on trabecular bone microarchitecture were assessed at two months by microcomputerized tomography (microCT). Chemically complex turmeric did not prevent bone loss, however, the curcuminoid-enriched turmeric prevented up to 50% of OVX-induced loss of trabecular bone and also preserved the number and connectedness of the strut-like trabeculae. These results suggest that turmeric may have bone-protective effects but that extract composition is a critical factor.

Protection of Trabecular Bone in Ovariectomized Rats by Turmeric (Curcuma longa L.) is Dependent on Extract Composition

PubMed Central

Wright, Laura E.; Frye, Jennifer B.; Timmermann, Barbara N.; Funk, Janet L.

2010-01-01

Extracts prepared from turmeric (Curcuma longa L., [Zingiberaceae]) containing bioactive phenolic curcuminoids were evaluated for bone-protective effects in a hypogonadal rat model of postmenopausal osteoporosis. Three-month female Sprague Dawley rats were ovariectomized (OVX) and treated with a chemically complex turmeric fraction (41% curcuminoids by weight) or a curcuminoid-enriched turmeric fraction (94% curcuminoids by weight), both dosed at 60mg/kg 3x per week, or vehicle alone. Effects of two months of treatment on OVX-induced bone loss were followed prospectively by serial assessment of bone mineral density (BMD) of the distal femur using dual-energy x-ray absorptiometry (DXA), while treatment effects on trabecular bone microarchitecture were assessed at two months by micro-computerized tomography (μCT). Chemically complex turmeric did not prevent bone loss, however, the curcuminoid-enriched turmeric prevented up to 50% of OVX-induced loss of trabecular bone and also preserved the number and connectedness of the strut-like trabeculae. These results suggest that turmeric may have bone-protective effects but that extract composition is a critical factor. PMID:20695490

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

PubMed

Sihota, Ramanjit; Goyal, Amita; Kaur, Jasbir; Gupta, Viney; Nag, Tapas C

2012-01-01

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

Diagnostic imaging of trabecular bone microstructure for oral implants: a literature review.

PubMed

Ibrahim, N; Parsa, A; Hassan, B; van der Stelt, P; Wismeijer, D

2013-01-01

Several dental implant studies have reported that radiographic evaluation of bone quality can aid in reducing implant failure. Bone quality is assessed in terms of its quantity, density, trabecular characteristics and cells. Current imaging modalities vary widely in their efficiency in assessing trabecular structures, especially in a clinical setting. Most are very costly, require an extensive scanning procedure coupled with a high radiation dose and are only partially suitable for patient use. This review examines the current literature regarding diagnostic imaging assessment of trabecular microstructure prior to oral implant placement and suggests cone beam CT as a method of choice for evaluating trabecular bone microstructure.

Trabecular Bone Mechanical Properties and Fractal Dimension

NASA Technical Reports Server (NTRS)

Hogan, Harry A.

1996-01-01

Countermeasures for reducing bone loss and muscle atrophy due to extended exposure to the microgravity environment of space are continuing to be developed and improved. An important component of this effort is finite element modeling of the lower extremity and spinal column. These models will permit analysis and evaluation specific to each individual and thereby provide more efficient and effective exercise protocols. Inflight countermeasures and post-flight rehabilitation can then be customized and targeted on a case-by-case basis. Recent Summer Faculty Fellowship participants have focused upon finite element mesh generation, muscle force estimation, and fractal calculations of trabecular bone microstructure. Methods have been developed for generating the three-dimensional geometry of the femur from serial section magnetic resonance images (MRI). The use of MRI as an imaging modality avoids excessive exposure to radiation associated with X-ray based methods. These images can also detect trabecular bone microstructure and architecture. The goal of the current research is to determine the degree to which the fractal dimension of trabecular architecture can be used to predict the mechanical properties of trabecular bone tissue. The elastic modulus and the ultimate strength (or strain) can then be estimated from non-invasive, non-radiating imaging and incorporated into the finite element models to more accurately represent the bone tissue of each individual of interest. Trabecular bone specimens from the proximal tibia are being studied in this first phase of the work. Detailed protocols and procedures have been developed for carrying test specimens through all of the steps of a multi-faceted test program. The test program begins with MRI and X-ray imaging of the whole bones before excising a smaller workpiece from the proximal tibia region. High resolution MRI scans are then made and the piece further cut into slabs (roughly 1 cm thick). The slabs are X-rayed again

Dynamic Simulation of Three Dimensional Architectural and Mechanical Alterations in Human Trabecular Bone during Menopause

PubMed Central

Liu, X. Sherry; Huang, Angela H.; Zhang, X. Henry; Sajda, Paul; Ji, Baohua; Guo, X. Edward

2008-01-01

A three dimensional (3D) computational simulation of dynamic process of trabecular bone remodeling was developed with all the parameters derived from physiological and clinical data. Contributions of the microstructural bone formation deficits: trabecular plate perforations, trabecular rod breakages, and isolated bone fragments, to the rapid bone loss and disruption of trabecular microarchitecture during menopause were studied. Eighteen human trabecular bone samples from femoral neck (FN) and spine were scanned using a micro computed tomography (μCT) system. Bone resorption and formation were simulated as a computational cycle corresponding to 40-day resorption/160-day formation. Resorption cavities were randomly created over the bone surface according to the activation frequency, which was strictly based on clinical data. Every resorption cavity was refilled during formation unless it caused trabecular plate perforation, trabecular rod breakage or isolated fragments. A 20-year-period starting 5 years before and ending 15 years after menopause was simulated for each specimen. Elastic moduli, standard and individual trabeculae segmentation (ITS)-based morphological parameters were evaluated for each simulated 3D image. For both spine and FN groups, the time courses of predicted bone loss pattern by microstructural bone formation deficits were fairly consistent with the clinical measurements. The percentage of bone loss due to trabecular plate perforation, trabecular rod breakage, and isolated bone fragments were 73.2%, 18.9% and 7.9% at the simulated 15 years after menopause. The ITS-based plate fraction (pBV/BV), mean plate surface area (pTb.S), plate number density (pTb.N), and mean rod thickness (rTb.Th) decreased while rod fraction (rBV/BV) and rod number density (rTb.N) increased after the simulated menopause. The dynamic bone remodeling simulation based on microstructural bone formation deficits predicted the time course of menopausal bone loss pattern of

Hyperfunctioning Solid/Trabecular Follicular Carcinoma of the Thyroid Gland

PubMed Central

Giovanella, Luca; Fasolini, Fabrizio; Suriano, Sergio; Mazzucchelli, Luca

2010-01-01

A 68-year-old woman with solid/trabecular follicular thyroid carcinoma inside of an autonomously functioning thyroid nodule is described in this paper. The patient was referred to our clinic for swelling of the neck and an increased pulse rate. Ultrasonography showed a slightly hypoechoic nodule in the right lobe of the thyroid. Despite suppressed TSH levels, the 99mTc-pertechnetate scan showed a hot area corresponding to the nodule with a suppressed uptake in the remaining thyroid tissue. Histopathological examination of the nodule revealed a solid/trabecular follicular thyroid carcinoma. To the best of our knowledge, this is the first case of hyperfunctioning follicular solid/trabecular carcinoma reported in the literature. Even if a hyperfunctioning thyroid carcinoma is an extremely rare malignancy, careful management is recommended so that a malignancy will not be overlooked in the hot thyroid nodules. PMID:20847957

Hyperfunctioning solid/trabecular follicular carcinoma of the thyroid gland.

PubMed

Giovanella, Luca; Fasolini, Fabrizio; Suriano, Sergio; Mazzucchelli, Luca

2010-01-01

A 68-year-old woman with solid/trabecular follicular thyroid carcinoma inside of an autonomously functioning thyroid nodule is described in this paper. The patient was referred to our clinic for swelling of the neck and an increased pulse rate. Ultrasonography showed a slightly hypoechoic nodule in the right lobe of the thyroid. Despite suppressed TSH levels, the (99m)Tc-pertechnetate scan showed a hot area corresponding to the nodule with a suppressed uptake in the remaining thyroid tissue. Histopathological examination of the nodule revealed a solid/trabecular follicular thyroid carcinoma. To the best of our knowledge, this is the first case of hyperfunctioning follicular solid/trabecular carcinoma reported in the literature. Even if a hyperfunctioning thyroid carcinoma is an extremely rare malignancy, careful management is recommended so that a malignancy will not be overlooked in the hot thyroid nodules.

Anorexia Nervosa: Analysis of Trabecular Texture with CT

PubMed Central

Tabari, Azadeh; Torriani, Martin; Miller, Karen K.; Klibanski, Anne; Kalra, Mannudeep K.

2017-01-01

Purpose To determine indexes of skeletal integrity by using computed tomographic (CT) trabecular texture analysis of the lumbar spine in patients with anorexia nervosa and normal-weight control subjects and to determine body composition predictors of trabecular texture. Materials and Methods This cross-sectional study was approved by the institutional review board and compliant with HIPAA. Written informed consent was obtained. The study included 30 women with anorexia nervosa (mean age ± standard deviation, 26 years ± 6) and 30 normal-weight age-matched women (control group). All participants underwent low-dose single-section quantitative CT of the L4 vertebral body with use of a calibration phantom. Trabecular texture analysis was performed by using software. Skewness (asymmetry of gray-level pixel distribution), kurtosis (pointiness of pixel distribution), entropy (inhomogeneity of pixel distribution), and mean value of positive pixels (MPP) were assessed. Bone mineral density and abdominal fat and paraspinal muscle areas were quantified with quantitative CT. Women with anorexia nervosa and normal-weight control subjects were compared by using the Student t test. Linear regression analyses were performed to determine associations between trabecular texture and body composition. Results Women with anorexia nervosa had higher skewness and kurtosis, lower MPP (P < .001), and a trend toward lower entropy (P = .07) compared with control subjects. Bone mineral density, abdominal fat area, and paraspinal muscle area were inversely associated with skewness and kurtosis and positively associated with MPP and entropy. Texture parameters, but not bone mineral density, were associated with lowest lifetime weight and duration of amenorrhea in anorexia nervosa. Conclusion Patients with anorexia nervosa had increased skewness and kurtosis and decreased entropy and MPP compared with normal-weight control subjects. These parameters were associated with lowest lifetime weight

Anorexia Nervosa: Analysis of Trabecular Texture with CT.

PubMed

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

2017-04-01

Purpose To determine indexes of skeletal integrity by using computed tomographic (CT) trabecular texture analysis of the lumbar spine in patients with anorexia nervosa and normal-weight control subjects and to determine body composition predictors of trabecular texture. Materials and Methods This cross-sectional study was approved by the institutional review board and compliant with HIPAA. Written informed consent was obtained. The study included 30 women with anorexia nervosa (mean age ± standard deviation, 26 years ± 6) and 30 normal-weight age-matched women (control group). All participants underwent low-dose single-section quantitative CT of the L4 vertebral body with use of a calibration phantom. Trabecular texture analysis was performed by using software. Skewness (asymmetry of gray-level pixel distribution), kurtosis (pointiness of pixel distribution), entropy (inhomogeneity of pixel distribution), and mean value of positive pixels (MPP) were assessed. Bone mineral density and abdominal fat and paraspinal muscle areas were quantified with quantitative CT. Women with anorexia nervosa and normal-weight control subjects were compared by using the Student t test. Linear regression analyses were performed to determine associations between trabecular texture and body composition. Results Women with anorexia nervosa had higher skewness and kurtosis, lower MPP (P < .001), and a trend toward lower entropy (P = .07) compared with control subjects. Bone mineral density, abdominal fat area, and paraspinal muscle area were inversely associated with skewness and kurtosis and positively associated with MPP and entropy. Texture parameters, but not bone mineral density, were associated with lowest lifetime weight and duration of amenorrhea in anorexia nervosa. Conclusion Patients with anorexia nervosa had increased skewness and kurtosis and decreased entropy and MPP compared with normal-weight control subjects. These parameters were associated with lowest lifetime weight

Attenuating trabecular morphology associated with low magnesium diet evaluated using micro computed tomography.

PubMed

Tu, Shu-Ju; Wang, Shun-Ping; Cheng, Fu-Chou; Weng, Chia-En; Huang, Wei-Tzu; Chang, Wei-Jeng; Chen, Ying-Ju

2017-01-01

The literature shows that bone mineral density (BMD) and the geometric architecture of trabecular bone in the femur may be affected by inadequate dietary intake of Mg. In this study, we used microcomputed tomography (micro-CT) to characterize and quantify the impact of a low-Mg diet on femoral trabecular bones in mice. Four-week-old C57BL/6J male mice were randomly assigned to 2 groups and supplied either a normal or low-Mg diet for 8weeks. Samples of plasma and urine were collected for biochemical analysis, and femur tissues were removed for micro-CT imaging. In addition to considering standard parameters, we regarded trabecular bone as a cylindrical rod and used computational algorithms for a technical assessment of the morphological characteristics of the bones. BMD (mg-HA/cm3) was obtained using a standard phantom. We observed a decline in the total tissue volume, bone volume, percent bone volume, fractal dimension, number of trabecular segments, number of connecting nodes, bone mineral content (mg-HA), and BMD, as well as an increase in the structural model index and surface-area-to-volume ratio in low-Mg mice. Subsequently, we examined the distributions of the trabecular segment length and radius, and a series of specific local maximums were identified. The biochemical analysis revealed a 43% (96%) decrease in Mg and a 40% (71%) decrease in Ca in plasma (urine excretion). This technical assessment performed using micro-CT revealed a lower population of femoral trabecular bones and a decrease in BMD at the distal metaphysis in the low-Mg mice. Examining the distributions of the length and radius of trabecular segments showed that the average length and radius of the trabecular segments in low-Mg mice are similar to those in normal mice.

Disrupted trabecular bone micro-architecture in middle-aged male HIV-infected treated patients.

PubMed

Sellier, P; Ostertag, A; Collet, C; Trout, H; Champion, K; Fernandez, S; Lopes, A; Morgand, M; Clevenbergh, P; Evans, J; Souak, S; de Vernejoul, M-C; Bergmann, J-F

2016-08-01

HIV-infected individuals are at increased risk of incident fractures. Evaluation of trabecular bone micro-architecture is an important tool to assess bone strength, but its use has not yet been reported in middle-aged HIV-infected male individuals. The aim of the study was to compare bone micro-architecture between HIV-infected and HIV-uninfected men. In this cross-sectional study, 53 HIV-infected male individuals with a mean (± standard deviation) age of 49 ± 9 years who had been receiving antiretroviral therapy including tenofovir disoproxil fumarate (DF) for at least 60 months were compared with 50 HIV-uninfected male controls, matched for age and ethnic origin. We studied the volumetric bone density and micro-architecture of the radius and tibia using high-resolution peripheral quantitative computed tomography (HR-p QCT). Volumetric trabecular bone density was 17% lower in the tibia (P < 10(-4) ) and 16% lower in the radius (P < 10(-3) ) in HIV-infected patients compared with controls. By contrast, the cortical bone density was normal at both sites. The tibial trabecular micro-architecture differed markedly between patients and controls: bone volume/total volume (BV/TV) and trabecular number were each 13% lower (P < 10(-4) for both). Trabecular separation and inhomogeneity of the network were 18% and 24% higher in HIV-infected patients than in controls, respectively. The radial BV/TV and trabecular thickness were each 13% lower (P < 10(-3) and 10(-2) , respectively). Cortical thickness was not different between the two groups. The findings of lower volumetric trabecular bone density and disrupted trabecular micro-architectural parameters in middle-aged male HIV-infected treated patients help to explain bone frailty in these patients. © 2016 British HIV Association.

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

NASA Astrophysics Data System (ADS)

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.

Prediction of trabecular bone qualitative properties using scanning quantitative ultrasound

NASA Astrophysics Data System (ADS)

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

2013-11-01

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

Trabecular architecture in the StW 352 fossil hominin calcaneus.

PubMed

Zeininger, Angel; Patel, Biren A; Zipfel, Bernhard; Carlson, Kristian J

2016-08-01

Australopithecus africanus has been interpreted as having a rigid lateral foot. One mechanism contributing to a rigid foot during push-off in humans is a calcaneocuboid joint (CCJ) with limited dorsiflexion and a "close-packed" talocalcaneal joint (TCJ). In contrast, apes likely have a greater CCJ range of motion and lack a close-packed TCJ. Differences in tarsal arthrokinematics may result in different joint loading environments. In Homo sapiens, we tested the hypothesis that dorsal and plantar CCJ and the TCJ show evidence of predictable habitual loading. In Pan troglodytes, Gorilla gorilla, Gorilla beringei, and Papio ursinus, we tested the hypothesis that only the dorsal CCJ shows evidence of predictable loading. Specifically, we predicted similarity in trabecular properties across the dorsal and plantar CCJ in H. sapiens, but dissimilarity in non-humans. Additionally, we investigated trabecular properties of an A. africanus calcaneus (StW 352) to evaluate joint loading patterns in this hominin and ultimately address the evolution of these properties in H. sapiens. Contrary to predictions, the H. sapiens dorsal CCJ has a significantly higher elongation index, bone volume fraction, trabecular thickness, and trabecular number than the plantar CCJ, while trabecular properties in non-humans do not always differ as predicted between regions. H. sapiens exhibits trabecular morphology indicative of less variable TCJ loading than other groups, having the most anisotropic and rod-like struts oriented in line with predicted principal loads. Multivariate analysis shows that the StW 352 dorsal CCJ matches P. ursinus best, while the plantar CCJ matches G. beringei best and the TCJ matches that of G. gorilla best. Overall patterns suggest that the StW 352 calcaneus experienced more variable loading than H. sapiens, but less variable loading than P. troglodytes, G. gorilla, G. beringei, and P. ursinus, consistent with a large range of foot movements, probably

Multi-scale modelling of elastic moduli of trabecular bone

PubMed Central

Hamed, Elham; Jasiuk, Iwona; Yoo, Andrew; Lee, YikHan; Liszka, Tadeusz

2012-01-01

We model trabecular bone as a nanocomposite material with hierarchical structure and predict its elastic properties at different structural scales. The analysis involves a bottom-up multi-scale approach, starting with nanoscale (mineralized collagen fibril) and moving up the scales to sub-microscale (single lamella), microscale (single trabecula) and mesoscale (trabecular bone) levels. Continuum micromechanics methods, composite materials laminate theory and finite-element methods are used in the analysis. Good agreement is found between theoretical and experimental results. PMID:22279160

Prediction of trabecular bone qualitative properties using scanning quantitative ultrasound

PubMed Central

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

2012-01-01

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

Effects of spaceflight on trabecular bone in rats

NASA Technical Reports Server (NTRS)

Jee, W. S. S.; Wronski, T. J.; Morey, E. R.; Kimmel, D. B.

1983-01-01

Alterations in trabecular bone were observed in growing male Wistar rats after 18.5 days of orbital flight on the COSMOS 1129 biosatellite. Spaceflight induced a decreased mass of mineralized tissue and an increased fat content of the bone marrow in the proximal tibial and humeral metaphyses. The osteoblast population appeared to decline immediately adjacent to the growth cartilage-metaphyseal junction, but osteoclast numbers were unchanged. These results suggested that bone formation may have been inhibited during spaceflight, but resorption remained constant. With the exception of trabecular bone mass in the proximal tibia, the observed skeletal changes returned to normal during a 29-day postflight period.

A theoretical framework for strain-related trabecular bone maintenance and adaptation.

PubMed

Ruimerman, R; Hilbers, P; van Rietbergen, B; Huiskes, R

2005-04-01

It is assumed that density and morphology of trabecular bone is partially controlled by mechanical forces. How these effects are expressed in the local metabolic functions of osteoclast resorption and osteoblast formation is not known. In order to investigate possible mechano-biological pathways for these mechanisms we have proposed a mathematical theory (Nature 405 (2000) 704). This theory is based on hypothetical osteocyte stimulation of osteoblast bone formation, as an effect of elevated strain in the bone matrix, and a role for microcracks and disuse in promoting osteoclast resorption. Applied in a 2-D Finite Element Analysis model, the theory explained the formation of trabecular patterns. In this article we present a 3-D FEA model based on the same theory and investigated its potential morphological predictability of metabolic reactions to mechanical loads. The computations simulated the development of trabecular morphological details during growth, relative to measurements in growing pigs, reasonably realistic. They confirmed that the proposed mechanisms also inherently lead to optimal stress transfer. Alternative loading directions produced new trabecular orientations. Reduction of load reduced trabecular thickness, connectivity and mass in the simulation, as is seen in disuse osteoporosis. Simulating the effects of estrogen deficiency through increased osteoclast resorption frequencies produced osteoporotic morphologies as well, as seen in post-menopausal osteoporosis. We conclude that the theory provides a suitable computational framework to investigate hypothetical relationships between bone loading and metabolic expressions.

Skeletal structure in postmenopausal women with osteopenia and fractures is characterized by abnormal trabecular plates and cortical thinning.

PubMed

Stein, Emily M; Kepley, Anna; Walker, Marcella; Nickolas, Thomas L; Nishiyama, Kyle; Zhou, Bin; Liu, X Sherry; McMahon, Donald J; Zhang, Chiyuan; Boutroy, Stephanie; Cosman, Felicia; Nieves, Jeri; Guo, X Edward; Shane, Elizabeth

2014-01-01

The majority of fragility fractures occur in women with osteopenia rather than osteoporosis as determined by dual‐energy X‐ray absorptiometry (DXA). However, it is difficult to identify which women with osteopenia are at greatest risk. We performed this study to determine whether osteopenic women with and without fractures had differences in trabecular morphology and biomechanical properties of bone. We hypothesized that women with fractures would have fewer trabecular plates, less trabecular connectivity, and lower stiffness. We enrolled 117 postmenopausal women with osteopenia by DXA (mean age 66 years; 58 with fragility fractures and 59 nonfractured controls). All had areal bone mineral density (aBMD) measured by DXA. Trabecular and cortical volumetric bone mineral density (vBMD), trabecular microarchitecture, and cortical porosity were measured by high‐resolution peripheral computed tomography (HR‐pQCT) of the distal radius and tibia. HR‐pQCT scans were subjected to finite element analysis to estimate whole bone stiffness and individual trabecula segmentation (ITS) to evaluate trabecular type (as plate or rod), orientation, and connectivity.Groups had similar age, race, body mass index (BMI), and mean T‐scores. Fracture subjects had lower cortical and trabecular vBMD, thinner cortices, and thinner, more widely separated trabeculae. By ITS, fracture subjects had fewer trabecular plates, less axially aligned trabeculae, and less trabecular connectivity. Whole bone stiffness was lower in women with fractures. Cortical porosity did not differ. Differences in cortical bone were found at both sites, whereas trabecular differences were more pronounced at the radius.In summary, postmenopausal women with osteopenia and fractures had lower cortical and trabecular vBMD; thinner, more widely separated and rodlike trabecular structure; less trabecular connectivity; and lower whole bone stiffness compared with controls,despite similar aBMD by DXA. Our results

Androgens have antiresorptive effects on trabecular disuse osteopenia independent from muscle atrophy.

PubMed

Laurent, Michaël R; Jardí, Ferran; Dubois, Vanessa; Schollaert, Dieter; Khalil, Rougin; Gielen, Evelien; Carmeliet, Geert; Claessens, Frank; Vanderschueren, Dirk

2016-12-01

Aging hypogonadal men are at increased risk of osteoporosis and sarcopenia. Testosterone is a potentially appealing strategy to prevent simultaneous bone and muscle loss. The androgen receptor (AR) mediates antiresorptive effects on trabecular bone via osteoblast-lineage cells, as well as muscle-anabolic actions. Sex steroids also modify the skeletal response to mechanical loading. However, it is unclear whether the effects of androgens on bone remain effective independent of mechanical stimulation or rather require indirect androgen effects via muscle. This study aims to characterize the effects and underlying mechanisms of androgens on disuse osteosarcopenia. Adult male mice received a unilateral botulinum toxin (BTx) injection, and underwent sham surgery or orchidectomy (ORX) without or with testosterone (ORX+T) or dihydrotestosterone (ORX+DHT) replacement. Compared to the contralateral internal control hindlimb, acute trabecular number and bone volume loss was increased by ORX and partially prevented DHT. T was more efficient and increased BV/TV in both hindlimbs over sham values, although it did not reduce the detrimental effect of BTx. Both androgens and BTx regulated trabecular osteoclast surface as well as tartrate-resistant acid phosphatase expression. Androgens also prevented BTx-induced body weight loss but did not significantly influence paralysis or muscle atrophy. BTx and ORX both reduced cortical thickness via endosteal expansion, which was prevented by T but not DHT. In long-term follow-up, the residual trabecular bone volume deficit in sham-BTx hindlimbs was prevented by DHT but T restored it more efficiently to pre-treatment levels. Conditional AR deletion in late osteoblasts and osteocytes or in the satellite cell lineage increased age-related trabecular bone loss in both hindlimbs without influencing the effect of BTx on trabecular osteopenia. We conclude that androgens have antiresorptive effects on trabecular disuse osteopenia which do not

A Wolff in sheep's clothing: trabecular bone adaptation in response to changes in joint loading orientation.

PubMed

Barak, Meir M; Lieberman, Daniel E; Hublin, Jean-Jacques

2011-12-01

This study tests Wolff's law of trabecular bone adaptation by examining if induced changes in joint loading orientation cause corresponding adjustments in trabecular orientation. Two groups of sheep were exercised at a trot, 15 min/day for 34 days on an inclined (7°) or level (0°) treadmills. Incline trotting caused the sheep to extend their tarsal joints by 3-4.5° during peak loading (P<0.01) but has no effect on carpal joint angle (P=0.984). Additionally, tarsal joint angle in the incline group sheep were maintained more extended throughout the day using elevated platform shoes on their forelimbs. A third "sedentary group" group did not run but wore platform shoes throughout the day. As predicted by Wolff's law, trabecular orientation in the distal tibia (tarsal joint) were more obtuse by 2.7 to 4.3° in the incline group compared to the level group; trabecular orientation was not significantly different in the sedentary and level groups. In addition, trabecular orientations in the distal radius (carpal joint) of the sedentary, level and incline groups did not differ between groups, and were aligned almost parallel to the radius long axis, corresponding to the almost straight carpal joint angle at peak loading. Measurements of other trabecular bone parameters revealed additional responses to loading, including significantly higher bone volume fraction (BV/TV), Trabecular number (Tb.N) and trabecular thickness (Tb.Th), lower trabecular spacing (Tb.Sp), and less rod-shaped trabeculae (higher structure model index, SMI) in the exercised than sedentary sheep. Overall, these results demonstrate that trabecular bone dynamically adjusts and realigns itself in very precise relation to changes in peak loading direction, indicating that Wolff's law is not only accurate but also highly sensitive. Copyright © 2011 Elsevier Inc. All rights reserved.

Trabecular architecture in the forelimb epiphyses of extant xenarthrans (Mammalia).

PubMed

Amson, Eli; Arnold, Patrick; van Heteren, Anneke H; Canoville, Aurore; Nyakatura, John A

2017-01-01

Bone structure has a crucial role in the functional adaptations that allow vertebrates to conduct their diverse lifestyles. Much has been documented regarding the diaphyseal structure of long bones of tetrapods. However, the architecture of trabecular bone, which is for instance found within the epiphyses of long bones, and which has been shown experimentally to be extremely plastic, has received little attention in the context of lifestyle adaptations (virtually only in primates). We therefore investigated the forelimb epiphyses of extant xenarthrans, the placental mammals including the sloths, anteaters, and armadillos. They are characterised by several lifestyles and degrees of fossoriality involving distinct uses of their forelimb. We used micro computed tomography data to acquire 3D trabecular parameters at regions of interest (ROIs) for all extant genera of xenarthrans (with replicates). Traditional, spherical, and phylogenetically informed statistics (including the consideration of size effects) were used to characterise the functional signal of these parameters. Several trabecular parameters yielded functional distinctions. The main direction of the trabeculae distinguished lifestyle categories for one ROI (the radial trochlea). Among the other trabecular parameters, it is the degree of anisotropy (i.e., a preferential alignment of the trabeculae) that yielded the clearest functional signal. For all ROIs, the armadillos, which represent the fully terrestrial and fossorial category, were found as characterised by a greater degree of anisotropy (i.e., more aligned trabeculae). Furthermore, the trabeculae of the humeral head of the most fossorial armadillos were also found to be more anisotropic than in the less fossorial species. Most parameters were marked by an important intraspecific variability and by a size effect, which could, at least partly, be masking the functional signal. But for some parameters, the degree of anisotropy in particular, a clear

MR-based trabecular bone microstructure is not altered in subjects with indolent systemic mastocytosis.

PubMed

Baum, Thomas; Karampinos, Dimitrios C; Brockow, Knut; Seifert-Klauss, Vanadin; Jungmann, Pia M; Biedermann, Tilo; Rummeny, Ernst J; Bauer, Jan S; Müller, Dirk

2015-01-01

Subjects with indolent systemic mastocytosis (ISM) have an increased risk for osteoporosis. It has been demonstrated that trabecular bone microstructure analysis improves the prediction of bone strength beyond dual-energy X-ray absorptiometry-based bone mineral density. The purpose of this study was to obtain Magnetic Resonance (MR)-based trabecular bone microstructure parameters as advanced imaging biomarkers in subjects with ISM (n=18) and compare them with those of normal controls (n=18). Trabecular bone microstructure parameters were not significantly (P>.05) different between subjects with ISM and controls. These findings revealed important pathophysiological information about ISM-associated osteoporosis and may limit the use of trabecular bone microstructure analysis in this clinical setting. Copyright © 2015 Elsevier Inc. All rights reserved.

Effect of Low-Dose MDCT and Iterative Reconstruction on Trabecular Bone Microstructure Assessment.

PubMed

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

2016-01-01

We investigated the effects of low-dose multi detector computed tomography (MDCT) in combination with statistical iterative reconstruction algorithms on trabecular bone microstructure parameters. Twelve donated vertebrae were scanned with the routine radiation exposure used in our department (standard-dose) and a low-dose protocol. Reconstructions were performed with filtered backprojection (FBP) and maximum-likelihood based statistical iterative reconstruction (SIR). Trabecular bone microstructure parameters were assessed and statistically compared for each reconstruction. Moreover, fracture loads of the vertebrae were biomechanically determined and correlated to the assessed microstructure parameters. Trabecular bone microstructure parameters based on low-dose MDCT and SIR significantly correlated with vertebral bone strength. There was no significant difference between microstructure parameters calculated on low-dose SIR and standard-dose FBP images. However, the results revealed a strong dependency on the regularization strength applied during SIR. It was observed that stronger regularization might corrupt the microstructure analysis, because the trabecular structure is a very small detail that might get lost during the regularization process. As a consequence, the introduction of SIR for trabecular bone microstructure analysis requires a specific optimization of the regularization parameters. Moreover, in comparison to other approaches, superior noise-resolution trade-offs can be found with the proposed methods.

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

PubMed

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

2011-05-17

This study investigated whether changes in hardness of human trabecular bone are associated with osteoarthritis. Twenty femoral heads extracted from subjects without musculoskeletal diseases (subject age: 49-83 years) and twenty femoral heads extracted from osteoarthritic subjects (subject age: 42-85 years) were tested. Sixty indentations were performed along the main trabecular direction of each sample at a fixed relative distance. Two microstructures were found on the indenting locations: packs of parallel-lamellae (PL) and secondary osteons (SO). A 25gf load was applied for 15s and the Vickers Hardness (HV) was assessed. Trabecular tissue extracted from osteoarthritic subjects was found to be about 13% less hard compared to tissue extracted from non-pathologic subjects. However, tissue hardness was not significantly affected by gender or age. The SO was 10% less hard than the PL for both pathologic and non-pathologic tissues. A hardness of 34.1HV for PL and 30.8HV for SO was found for the non-pathologic tissue. For osteoarthritic tissue, the hardness was 30.2HV for PL and 27.1HV for SO. In the bone tissue extracted from osteoarthritic subjects the occurrence of indenting a SO (28%) was higher than that observed in the non-pathological tissue (15%). Osteoarthritis is associated with reduced tissue hardness and alterations in microstructure of the trabecular bone tissue. Gender does not significantly affect trabecular bone hardness either in non-pathological or osteoarthritic subjects. A similar conclusion can be drawn for age, although a larger donor sample size would be necessary to definitively exclude the existence of a slight effect. Copyright © 2011. Published by Elsevier Ltd.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Solis-Najera, S. E., E-mail: solisnajera@ciencias.unam.mx, E-mail: angel.perez@ciencias.unam.mx, E-mail: lucia.medina@ciencias.unam.mx; Neria-Pérez, J. A., E-mail: solisnajera@ciencias.unam.mx, E-mail: angel.perez@ciencias.unam.mx, E-mail: lucia.medina@ciencias.unam.mx; Medina, L., E-mail: solisnajera@ciencias.unam.mx, E-mail: angel.perez@ciencias.unam.mx, E-mail: lucia.medina@ciencias.unam.mx

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

Zone-dependent changes in human vertebral trabecular bone: clinical implications.

PubMed

Thomsen, Jesper Skovhus; Ebbesen, E N; Mosekilde, Li

2002-05-01

We have previously shown that there are pronounced age-related changes in human vertebral cancellous bone density and microarchitecture. However, the magnitude of these changes seemed to be dependent on zone location in the vertebral body-the central third vs. the areas adjacent to the endplates. The aim of the present study was, therefore, to investigate whether such zone-specific differences could be identified by static histomorphometric measures. The material comprised 48 individuals (24 women aged 19-97 years, and 24 men aged 23-95 years). Three of the women had a known fracture of the L-2. From each L-2, thick frontal sections of half of the vertebra were embedded undecalcified in methylmethacrylate, cut into 10-microm-thick sections, and stained with aniline blue. The sections were scanned into a computer, and classic static histomorphometry was performed on the images. The histomorphometry was performed on both the whole section and on the separate zones (central and sub-endplate zone). The results showed that trabecular bone volume, trabecular number, and connectivity density decreased significantly faster with age, whereas marrow space star volume increased significantly faster with age in the zones adjacent to the endplates than in the central zone. The other histomorphometric measures showed no zone specificity in relation to aging. However, trabecular thickness and trabecular separation were both higher at all ages in the central zone than in the sub-endplate zone, although this was significant only for trabecular separation. The described differences might have significant clinical implications concerning quantitative computed tomography (QCT) scanning, X-ray analyses, and assessment of fracture liability in the human spine, but the underlying pathogenesis is still not known. This study shows that the human vertebral body can be described as two distinct zones with very specific age-related changes in density and microstructure. This zone

Quasi-static and ratcheting properties of trabecular bone under uniaxial and cyclic compression.

PubMed

Gao, Li-Lan; Wei, Chao-Lei; Zhang, Chun-Qiu; Gao, Hong; Yang, Nan; Dong, Li-Min

2017-08-01

The quasi-static and ratcheting properties of trabecular bone were investigated by experiments and theoretical predictions. The creep tests with different stress levels were completed and it is found that both the creep strain and creep compliance increase rapidly at first and then increase slowly as the creep time goes by. With increase of compressive stress the creep strain increases and the creep compliance decreases. The uniaxial compressive tests show that the applied stress rate makes remarkable influence on the compressive behaviors of trabecular bone. The Young's modulus of trabecular bone increases with increase of stress rate. The stress-strain hysteresis loops of trabecular bone under cyclic load change from sparse to dense with increase of number of cycles, which agrees with the change trend of ratcheting strain. The ratcheting strain rate rapidly decreases at first, and then exhibits a relatively stable and small value after 50cycles. Both the ratcheting strain and ratcheting strain rate increase with increase of stress amplitude or with decrease of stress rate. The creep model and the nonlinear viscoelastic constitutive model of trabecular bone were proposed and used to predict its creep property and rate-dependent compressive property. The results show that there are good agreements between the experimental data and predictions. Copyright © 2017 Elsevier B.V. All rights reserved.

Muscle volume is related to trabecular and cortical bone architecture in typically developing children.

PubMed

Bajaj, Deepti; Allerton, Brianne M; Kirby, Joshua T; Miller, Freeman; Rowe, David A; Pohlig, Ryan T; Modlesky, Christopher M

2015-12-01

Muscle is strongly related to cortical bone architecture in children; however, the relationship between muscle volume and trabecular bone architecture is poorly studied. The aim of this study was to determine if muscle volume is related to trabecular bone architecture in children and if the relationship is different than the relationship between muscle volume and cortical bone architecture. Forty typically developing children (20 boys and 20 girls; 6 to 12y) were included in the study. Measures of trabecular bone architecture [i.e., apparent trabecular bone volume to total volume (appBV/TV), trabecular number (appTb.N), trabecular thickness (appTb.Th) and trabecular separation (appTb.Sp)] in the distal femur, cortical bone architecture [cortical volume, total volume, section modulus (Z) and polar moment of inertia (J)] in the midfemur, muscle volume in the midthigh and femur length were assessed using magnetic resonance imaging. Total physical activity and moderate-to-vigorous physical activity were assessed using an accelerometer-based activity monitor worn around the waist for four days. Calcium intake was assessed using diet records. Relationships among the measures were tested using multiple linear regression analysis. Muscle volume was moderately-to-strongly related to measures of trabecular bone architecture [appBV/TV (r=0.81), appTb.N (r=0.53), appTb.Th (r=0.67), appTb.Sp (r=-0.71); all p<0.001] but more strongly related to measures of cortical bone architecture [cortical volume (r=0.96), total volume (r=0.94), Z (r=0.94) and J (r=0.92; all p<0.001)]. Similar relationships were observed between femur length and measures of trabecular (p<0.01) and cortical (p<0.001) bone architecture. Sex, physical activity and calcium intake were not related to any measure of bone architecture (p>0.05). Because muscle volume and femur length were strongly related (r=0.91, p<0.001), muscle volume was scaled for femur length (muscle volume/femur length(2.77)). When muscle

Muscle volume is related to trabecular and cortical bone architecture in typically developing children

PubMed Central

Bajaj, Deepti; Allerton, Brianne M.; Kirby, Joshua T.; Miller, Freeman; Rowe, David A.; Pohlig, Ryan T.; Modlesky, Christopher M.

2016-01-01

Introduction Muscle is strongly related to cortical bone architecture in children; however, the relationship between muscle volume and trabecular bone architecture is poorly studied. The aim of this study was to determine if muscle volume is related to trabecular bone architecture in children and if the relationship is different than the relationship between muscle volume and cortical bone architecture. Materials and methods Forty typically developing children (20 boys and 20 girls; 6 to 12 y) were included in the study. Measures of trabecular bone architecture [apparent trabecular bone volume to total volume (appBV/TV), trabecular number (appTb.N), trabecular thickness (appTb.Th), and trabecular separation (appTb.Sp)] in the distal femur, cortical bone architecture [(cortical volume, medullary volume, total volume, polar moment of inertia (J) and section modulus (Z)] in the midfemur, muscle volume in the midthigh and femur length were assessed using magnetic resonance imaging. Total and moderate-to-vigorous physical activity were assessed using an accelerometer-based activity monitor worn around the waist for four days. Calcium intake was assessed using diet records. Relationships among the measures were tested using multiple linear regression analysis. Results Muscle volume was moderately-to-strongly related to measures of trabecular bone architecture [appBV/TV (r = 0.81, appTb.N (r = 0.53), appTb.Th (r = 0.67), appTb.Sp (r = −0.71; all p < 0.001] but more strongly related to measures of cortical bone architecture [cortical volume (r = 0.96), total volume (r = 0.94), Z (r = 0.94) and J (r = 0.92; all p < 0.001)]. Similar relationships were observed between femur length and measures of trabecular (p < 0.01) and cortical (p < 0.001) bone architecture. Sex, physical activity and calcium intake were not related to any measure of bone architecture (p > 0.05). Because muscle volume and femur length were strongly related (r = 0.91, p < 0.001), muscle volume was scaled

iStent trabecular micro-bypass stent for open-angle glaucoma

PubMed Central

Le, Kim; Saheb, Hady

2014-01-01

Trabecular micro-bypass stents, commonly known as iStents, are micro-invasive glaucoma surgery (MIGS) devices used to treat open-angle glaucoma. Like other MIGS procedures that enhance trabecular outflow, the iStent lowers intraocular pressure (IOP) by creating a direct channel between the anterior chamber and Schlemm’s canal. iStents are typically implanted at the time of phacoemulsification for patients with open-angle glaucoma and visually significant cataracts. This review summarizes the published data regarding the efficacy, safety, and cost considerations of trabecular micro-bypass stents. Most studies found statistically significant reductions in mean IOP and ocular medication use after combined phacoemulsification with single or double iStent implantation. The devices were found to be very safe, with a safety profile similar to that of cataract surgery. Complications were infrequent, with the most common complications being temporary stent obstruction or malposition, which resolved with observation or secondary procedures. Future studies are needed to evaluate long-term outcomes, patient satisfaction, cost effectiveness, and expanded indications. PMID:25284980

Spine Trabecular Bone Score as an Indicator of Bone Microarchitecture at the Peripheral Skeleton in Kidney Transplant Recipients.

PubMed

Luckman, Matthew; Hans, Didier; Cortez, Natalia; Nishiyama, Kyle K; Agarawal, Sanchita; Zhang, Chengchen; Nikkel, Lucas; Iyer, Sapna; Fusaro, Maria; Guo, Edward X; McMahon, Donald J; Shane, Elizabeth; Nickolas, Thomas L

2017-04-03

Studies using high-resolution peripheral quantitative computed tomography showed progressive abnormalities in cortical and trabecular microarchitecture and biomechanical competence over the first year after kidney transplantation. However, high-resolution peripheral computed tomography is a research tool lacking wide availability. In contrast, the trabecular bone score is a novel and widely available tool that uses gray-scale variograms of the spine image from dual-energy x-ray absorptiometry to assess trabecular quality. There are no studies assessing whether trabecular bone score characterizes bone quality in kidney transplant recipients. Between 2009 and 2010, we conducted a study to assess changes in peripheral skeletal microarchitecture, measured by high-resolution peripheral computed tomography, during the first year after transplantation in 47 patients managed with early corticosteroid-withdrawal immunosuppression. All adult first-time transplant candidates were eligible. Patients underwent imaging with high-resolution peripheral computed tomography and dual-energy x-ray absorptiometry pretransplantation and 3, 6, and 12 months post-transplantation. We now test if, during the first year after transplantation, trabecular bone score assesses the evolution of bone microarchitecture and biomechanical competence as determined by high-resolution peripheral computed tomography. At baseline and follow-up, among the 72% and 78%, respectively, of patients having normal bone mineral density by dual-energy x-ray absorptiometry, 53% and 50%, respectively, were classified by trabecular bone score as having high fracture risk. At baseline, trabecular bone score correlated with spine, hip, and ultradistal radius bone mineral density by dual-energy x-ray absorptiometry and cortical area, density, thickness, and porosity; trabecular density, thickness, separation, and heterogeneity; and stiffness and failure load by high-resolution peripheral computed tomography

Spine Trabecular Bone Score as an Indicator of Bone Microarchitecture at the Peripheral Skeleton in Kidney Transplant Recipients

PubMed Central

Luckman, Matthew; Hans, Didier; Cortez, Natalia; Nishiyama, Kyle K.; Agarawal, Sanchita; Zhang, Chengchen; Nikkel, Lucas; Iyer, Sapna; Fusaro, Maria; Guo, Edward X.; McMahon, Donald J.; Shane, Elizabeth

2017-01-01

Background and objectives Studies using high-resolution peripheral quantitative computed tomography showed progressive abnormalities in cortical and trabecular microarchitecture and biomechanical competence over the first year after kidney transplantation. However, high-resolution peripheral computed tomography is a research tool lacking wide availability. In contrast, the trabecular bone score is a novel and widely available tool that uses gray-scale variograms of the spine image from dual-energy x-ray absorptiometry to assess trabecular quality. There are no studies assessing whether trabecular bone score characterizes bone quality in kidney transplant recipients. Design, settings, participants, & measurements Between 2009 and 2010, we conducted a study to assess changes in peripheral skeletal microarchitecture, measured by high-resolution peripheral computed tomography, during the first year after transplantation in 47 patients managed with early corticosteroid–withdrawal immunosuppression. All adult first-time transplant candidates were eligible. Patients underwent imaging with high-resolution peripheral computed tomography and dual-energy x-ray absorptiometry pretransplantation and 3, 6, and 12 months post-transplantation. We now test if, during the first year after transplantation, trabecular bone score assesses the evolution of bone microarchitecture and biomechanical competence as determined by high-resolution peripheral computed tomography. Results At baseline and follow-up, among the 72% and 78%, respectively, of patients having normal bone mineral density by dual-energy x-ray absorptiometry, 53% and 50%, respectively, were classified by trabecular bone score as having high fracture risk. At baseline, trabecular bone score correlated with spine, hip, and ultradistal radius bone mineral density by dual-energy x-ray absorptiometry and cortical area, density, thickness, and porosity; trabecular density, thickness, separation, and heterogeneity; and

The development of the trabecular meshwork and its abnormality in primary infantile glaucoma.

PubMed Central

Anderson, D R

1981-01-01

Tissue from ten eyes with infantile glaucoma and from 40 normal eyes of fetuses and infants without glaucoma were examined by light and electron microscopy. In normal development, the corneoscleral coat grows faster than the uveal tract during the last trimester, leading to a posterior migration of the ciliary body attachment from Schwalbe's line (5th month) to the scleral spur (9th month), and then to a location behind the scleral spur (postnatally). In infantile glaucoma, the insertion of the anterior ciliary body and iris overlaps the trabecular meshwork, similar to the late fetal position. The trabecular sheets are perforated, and there is no membrane over the surface of the trabecular meshwork. The trabecular beams are thicker than in normal infant eyes. There is both histologic and clinical evidence of traction on the iris root exerted by the thickened trabecular beams. These findings suggest that in congenital glaucoma the thickened beams had prevented the normal posterior migration of the ciliary body and iris root. This traction may compact the thickened trabecular beams, obstructing aqueous humor outflow. Release of the traction by an incision (goniotomy or trabeculotomy) of the thickened meshwork may relieve the obstruction. Of uncertain pathological significance is that there are no vacuoles in the endothelium of Schlemm's canal and there is a broad layer of collagen and amorphous material in the juxtacanalicular connective tissue. The ciliary processes are elongated inward, as if they were pulled by zonular traction (perhaps created by an enlarging diameter of the limbus with a fixed lens diameter). Images FIGURE 7 FIGURE 8 FIGURE 10 FIGURE 11 FIGURE 20 A FIGURE 20 B FIGURE 1 FIGURE 3 FIGURE 4 A FIGURE 4 B FIGURE 5 A FIGURE 5 B FIGURE 6 FIGURE 9 FIGURE 12 FIGURE 13 FIGURE 14 FIGURE 15 FIGURE 16 FIGURE 17 FIGURE 18 FIGURE 19 PMID:7342408

Estimation of trabecular bone parameters in children from multisequence MRI using texture-based regression

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lekadir, Karim, E-mail: karim.lekadir@upf.edu; Hoogendoorn, Corné; Armitage, Paul

Purpose: This paper presents a statistical approach for the prediction of trabecular bone parameters from low-resolution multisequence magnetic resonance imaging (MRI) in children, thus addressing the limitations of high-resolution modalities such as HR-pQCT, including the significant exposure of young patients to radiation and the limited applicability of such modalities to peripheral bones in vivo. Methods: A statistical predictive model is constructed from a database of MRI and HR-pQCT datasets, to relate the low-resolution MRI appearance in the cancellous bone to the trabecular parameters extracted from the high-resolution images. The description of the MRI appearance is achieved between subjects by usingmore » a collection of feature descriptors, which describe the texture properties inside the cancellous bone, and which are invariant to the geometry and size of the trabecular areas. The predictive model is built by fitting to the training data a nonlinear partial least square regression between the input MRI features and the output trabecular parameters. Results: Detailed validation based on a sample of 96 datasets shows correlations >0.7 between the trabecular parameters predicted from low-resolution multisequence MRI based on the proposed statistical model and the values extracted from high-resolution HRp-QCT. Conclusions: The obtained results indicate the promise of the proposed predictive technique for the estimation of trabecular parameters in children from multisequence MRI, thus reducing the need for high-resolution radiation-based scans for a fragile population that is under development and growth.« less

Disuse bone loss in hindquarter suspended rats: partial weightbearing, exercise and ibandronate treatment as countermeasures

NASA Technical Reports Server (NTRS)

Schultheis, L.; Ruff, C. B.; Rastogi, S.; Bloomfield, S.; Hogan, H. A.; Fedarko, N.; Thierry-Palmer, M.; Ruiz, J.; Bauss, F.; Shapiro, J. R.

2000-01-01

The purpose of this study was to evaluate potential countermeasures for bone loss during long-term space missions in the hindquarter suspended rat, including partial weight bearing (surrogate for artificial gravity) episodic full weight bearing (2 hour/day full weight bearing) and treatment with the third generation bisphosphonate ibandronate (Roche). Graded mechanical loading was studied by housing the animals on a novel servo controlled force plate system which permitted the titration of mechanical force at varying frequency and amplitude and different levels of weight bearing. The force plate, which forms the cage floor, is a glass platform supported by an 18" diameter speaker cone filled with expanding polyurethane foam. An infrared optical sensor attached to the speaker cone yields a voltage linearly related to vertical displacement of the glass platform. The dynamic force on the paw was computed as a product of the apparent mass of the animal on the platform at rest and the acceleration of the platform determined from the second derivative of the optical sensor output. The mass of the animal on the platform was varied by adjusting tension on the tether suspending the animal. Mechanical impact loading was titrated with the force plate resonating at different frequencies, including 3 Hz and 16 Hz.

Lattice strains and load partitioning in bovine trabecular bone.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Akhtar, R.; Daymond, M. R.; Almer, J. D.

2012-02-01

Microdamage and failure mechanisms have been well characterized in bovine trabecular bone. However, little is known about how elastic strains develop in the apatite crystals of the trabecular struts and their relationship with different deformation mechanisms. In this study, wide-angle high-energy synchrotron X-ray diffraction has been used to determine bulk elastic strains under in situ compression. Dehydrated bone is compared to hydrated bone in terms of their response to load. During compression, load is initially borne by trabeculae aligned parallel to loading direction with non-parallel trabeculae deforming by bending. Ineffective load partitioning is noted in dehydrated bone whereas hydrated bonemore » behaves like a plastically yielding foam« less

Creep of trabecular bone from the human proximal tibia

PubMed Central

Novitskaya, Ekaterina; Zin, Carolyn; Chang, Neil; Cory, Esther; Chen, Peter; D'Lima, Darryl; Sah, Robert L.; McKittrick, Joanna

2014-01-01

Creep is the deformation that occurs under a prolonged, sustained load and can lead to permanent damage in bone. Creep in bone is a complex phenomenon and varies with type of loading and local mechanical properties. Human trabecular bone samples from proximal tibia were harvested from a 71-year old female cadaver with osteoporosis. The samples were initially subjected to one cycle load up to 1% strain to determine the creep load. Samples were then loaded in compression under a constant stress for two hours and immediately unloaded. All tests were conducted with the specimens soaked in phosphate buffered saline with proteinase inhibitors at 37°C. Steady state creep rate and final creep strain were estimated from mechanical testing and compared with published data. The steady state creep rate correlated well with values obtained from bovine tibial and human vertebral trabecular bone, and was higher for lower density samples. Tissue architecture was analyzed by micro-computed tomography (μCT) both before and after creep testing to assess creep deformation and damage accumulated. Quantitative morphometric analysis indicated that creep induced changes in trabecular separation and the structural model index. A main mode of deformation was bending of trabeculae. PMID:24857486

Pore cross-section area on predicting elastic properties of trabecular bovine bone for human implants.

PubMed

Maciel, Alfredo; Presbítero, Gerardo; Piña, Cristina; del Pilar Gutiérrez, María; Guzmán, José; Munguía, Nadia

2015-01-01

A clear understanding of the dependence of mechanical properties of bone remains a task not fully achieved. In order to estimate the mechanical properties in bones for implants, pore cross-section area, calcium content, and apparent density were measured in trabecular bone samples for human implants. Samples of fresh and defatted bone tissue, extracted from one year old bovines, were cut in longitudinal and transversal orientation of the trabeculae. Pore cross-section area was measured with an image analyzer. Compression tests were conducted into rectangular prisms. Elastic modulus presents a linear tendency as a function of pore cross-section area, calcium content and apparent density regardless of the trabecular orientation. The best variable to estimate elastic modulus of trabecular bone for implants was pore cross-section area, and affirmations to consider Nukbone process appropriated for marrow extraction in trabecular bone for implantation purposes are proposed, according to bone mechanical properties. Considering stress-strain curves, defatted bone is stiffer than fresh bone. Number of pores against pore cross-section area present an exponential decay, consistent for all the samples. These graphs also are useful to predict elastic properties of trabecular samples of young bovines for implants.

Geodesic topological analysis of trabecular bone microarchitecture from high-spatial resolution magnetic resonance images.

PubMed

Carballido-Gamio, Julio; Krug, Roland; Huber, Markus B; Hyun, Ben; Eckstein, Felix; Majumdar, Sharmila; Link, Thomas M

2009-02-01

In vivo assessment of trabecular bone microarchitecture could improve the prediction of fracture risk and the efficacy of osteoporosis treatment and prevention. Geodesic topological analysis (GTA) is introduced as a novel technique to quantify the trabecular bone microarchitecture from high-spatial resolution magnetic resonance (MR) images. Trabecular bone parameters that quantify the scale, topology, and anisotropy of the trabecular bone network in terms of its junctions are the result of GTA. The reproducibility of GTA was tested with in vivo images of human distal tibiae and radii (n = 6) at 1.5 Tesla; and its ability to discriminate between subjects with and without vertebral fracture was assessed with ex vivo images of human calcanei at 1.5 and 3.0 Tesla (n = 30). GTA parameters yielded an average reproducibility of 4.8%, and their individual areas under the curve (AUC) of the receiver operating characteristic curve analysis for fracture discrimination performed better at 3.0 than at 1.5 Tesla reaching values of up to 0.78 (p < 0.001). Logistic regression analysis demonstrated that fracture discrimination was improved by combining GTA parameters, and that GTA combined with bone mineral density (BMD) allow for better discrimination than BMD alone (AUC = 0.95; p < 0.001). Results indicate that GTA can substantially contribute in studies of osteoporosis involving imaging of the trabecular bone microarchitecture. Copyright 2009 Wiley-Liss, Inc.

Improved 3D skeletonization of trabecular bone images derived from in vivo MRI

NASA Astrophysics Data System (ADS)

Magland, Jeremy F.; Wehrli, Felix W.

2008-03-01

Independent of overall bone density, 3D trabecular bone (TB) architecture has been shown to play an important role in conferring strength to the skeleton. Advances in imaging technologies such as micro-computed tomography (CT) and micro-magnetic resonance (MR) now permit in vivo imaging of the 3D trabecular network in the distal extremities. However, various experimental factors preclude a straightforward analysis of the 3D trabecular structure on the basis of these in vivo images. For MRI, these factors include blurring due to patient motion, partial volume effects, and measurement noise. While a variety of techniques have been developed to deal with the problem of patient motion, the second and third issues are inherent limitations of the modality. To address these issues, we have developed a series of robust processing steps to be applied to a 3D MR image and leading to a 3D skeleton that accurately represents the trabecular bone structure. Here we describe the algorithm, provide illustrations of its use with both specimen and in vivo micro-MR images, and discuss the accuracy and quantify the relationship between the original bone structure and the resulting 3D skeleton volume.

Structure Model Index Does Not Measure Rods and Plates in Trabecular Bone

PubMed Central

Salmon, Phil L.; Ohlsson, Claes; Shefelbine, Sandra J.; Doube, Michael

2015-01-01

Structure model index (SMI) is widely used to measure rods and plates in trabecular bone. It exploits the change in surface curvature that occurs as a structure varies from spherical (SMI = 4), to cylindrical (SMI = 3) to planar (SMI = 0). The most important assumption underlying SMI is that the entire bone surface is convex and that the curvature differential is positive at all points on the surface. The intricate connections within the trabecular continuum suggest that a high proportion of the surface could be concave, violating the assumption of convexity and producing regions of negative differential. We implemented SMI in the BoneJ plugin and included the ability to measure the amounts of surface that increased or decreased in area after surface mesh dilation, and the ability to visualize concave and convex regions. We measured SMI and its positive (SMI+) and negative (SMI−) components, bone volume fraction (BV/TV), the fraction of the surface that is concave (CF), and mean ellipsoid factor (EF) in trabecular bone using 38 X-ray microtomography (XMT) images from a rat ovariectomy model of sex steroid rescue of bone loss, and 169 XMT images from a broad selection of 87 species’ femora (mammals, birds, and a crocodile). We simulated bone resorption by eroding an image of elephant trabeculae and recording SMI and BV/TV at each erosion step. Up to 70%, and rarely <20%, of the trabecular surface is concave (CF 0.155–0.700). SMI is unavoidably influenced by aberrations induced by SMI−, which is strongly correlated with BV/TV and CF. The plate-to-rod transition in bone loss is an erroneous observation resulting from the close and artifactual relationship between SMI and BV/TV. SMI cannot discern between the distinctive trabecular geometries typical of mammalian and avian bone, whereas EF clearly detects birds’ more plate-like trabeculae. EF is free from confounding relationships with BV/TV and CF. SMI results reported in the literature should be

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

PubMed

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

2018-03-01

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

Nonhuman anthropoid primate femoral neck trabecular architecture and its relationship to locomotor mode.

PubMed

Fajardo, Roberto J; Müller, Ralph; Ketcham, Rich A; Colbert, Matthew

2007-04-01

Functional analyses of human and nonhuman anthropoid primate femoral neck structure have largely ignored the trabecular bone. We tested hypotheses regarding differences in the relative distribution and structural anisotropy of trabecular bone in the femoral neck of quadrupedal and climbing/suspensory anthropoids. We used high-resolution X-ray computed tomography to analyze quantitatively the femoral neck trabecular structure of Ateles geoffroyi, Symphalangus syndactylus, Alouatta seniculus, Colobus guereza, Macaca fascicularis, and Papio cynocephalus (n = 46). We analyzed a size-scaled superior and inferior volume of interest (VOI) in the femoral neck. The ratio of the superior to inferior VOI bone volume fraction indicated that the distribution of trabecular bone was inferiorly skewed in most (but not all) quadrupeds and evenly distributed the climbing/suspensory species, but interspecific comparisons indicated that all taxa overlapped in these measurements. Degree of anisotropy values were generally higher in the inferior VOI of all species and the results for the two climbing/suspensory taxa, A. geoffroyi (1.71 +/- 0.30) and S. syndactylus (1.55 +/- 0.04), were similar to the results for the quadrupedal anthropoids, C. guereza (male = 1.64 +/- 0.13; female = 1.68 +/- 0.07) and P. cynocephalus (1.47 +/- 0.13). These results suggest strong trabecular architecture similarity across body sizes, anthropoid phylogenetic backgrounds, and locomotor mode. This structural similarity might be explained by greater similarity in anthropoid hip joint loading mechanics than previously considered. It is likely that our current models of anthropoid hip joint mechanics are overly simplistic.

Genetic Determinants of Trabecular and Cortical Volumetric Bone Mineral Densities and Bone Microstructure

PubMed Central

Kähönen, Mika; Raitakari, Olli; Laaksonen, Marika; Sievänen, Harri; Viikari, Jorma; Lyytikäinen, Leo-Pekka; Mellström, Dan; Karlsson, Magnus; Ljunggren, Östen; Grundberg, Elin; Kemp, John P.; Sayers, Adrian; Nethander, Maria; Evans, David M.; Vandenput, Liesbeth; Tobias, Jon H.; Ohlsson, Claes

2013-01-01

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 that a genetic

A single scan skeletonization algorithm: application to medical imaging of trabecular bone

NASA Astrophysics Data System (ADS)

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

2010-03-01

Shape description is an important step in image analysis. The skeleton is used as a simple, compact representation of a shape. A skeleton represents the line centered in the shape and must be homotopic and one point wide. Current skeletonization algorithms compute the skeleton over several image scans, using either thinning algorithms or distance transforms. The principle of thinning is to delete points as one goes along, preserving the topology of the shape. On the other hand, the maxima of the local distance transform identifies the skeleton and is an equivalent way to calculate the medial axis. However, with this method, the skeleton obtained is disconnected so it is required to connect all the points of the medial axis to produce the skeleton. In this study we introduce a translated distance transform and adapt an existing distance driven homotopic algorithm to perform skeletonization with a single scan and thus allow the processing of unbounded images. This method is applied, in our study, on micro scanner images of trabecular bones. We wish to characterize the bone micro architecture in order to quantify bone integrity.

Influence of Trabecular Bone on Peri-Implant Stress and Strain Based on Micro-CT Finite Element Modeling of Beagle Dog

PubMed Central

Liao, Sheng-hui; Zhu, Xing-hao; Xie, Jing; Sohodeb, Vikesh Kumar; Ding, Xi

2016-01-01

The objective of this investigation is to analyze the influence of trabecular microstructure modeling on the biomechanical distribution of the implant-bone interface. Two three-dimensional finite element mandible models, one with trabecular microstructure (a refined model) and one with macrostructure (a simplified model), were built. The values of equivalent stress at the implant-bone interface in the refined model increased compared with those of the simplified model and strain on the contrary. The distributions of stress and strain were more uniform in the refined model of trabecular microstructure, in which stress and strain were mainly concentrated in trabecular bone. It was concluded that simulation of trabecular bone microstructure had a significant effect on the distribution of stress and strain at the implant-bone interface. These results suggest that trabecular structures could disperse stress and strain and serve as load buffers. PMID:27403424

Influence of Trabecular Bone on Peri-Implant Stress and Strain Based on Micro-CT Finite Element Modeling of Beagle Dog.

PubMed

Liao, Sheng-Hui; Zhu, Xing-Hao; Xie, Jing; Sohodeb, Vikesh Kumar; Ding, Xi

2016-01-01

The objective of this investigation is to analyze the influence of trabecular microstructure modeling on the biomechanical distribution of the implant-bone interface. Two three-dimensional finite element mandible models, one with trabecular microstructure (a refined model) and one with macrostructure (a simplified model), were built. The values of equivalent stress at the implant-bone interface in the refined model increased compared with those of the simplified model and strain on the contrary. The distributions of stress and strain were more uniform in the refined model of trabecular microstructure, in which stress and strain were mainly concentrated in trabecular bone. It was concluded that simulation of trabecular bone microstructure had a significant effect on the distribution of stress and strain at the implant-bone interface. These results suggest that trabecular structures could disperse stress and strain and serve as load buffers.

Experiment K305: Quantitative analysis of selected bone parameters. Supplement 3A: Trabecular spacing and orientation in the long bones

NASA Technical Reports Server (NTRS)

Judy, M. M.

1981-01-01

Values of mean trabecular spacing computed from optical diffraction patterns of 1:1 X-ray micrographs of tibial metaphysis and those obtained by standard image digitization techniques show excellent agreement. Upper limits on values of mean trabecular orientation deduced from diffraction patterns and the images are also in excellent agreement. Values of the ratio of mean trabecular spatial density in a region of 300 micrometers distal to the downwardly directed convexity in the cartilage growth plate to the value adjacent to the plate determined for flight animals sacrificed at recovery were significantly smaller than values for vivarium control animals. No significant differences were found in proximal regions. No significant differences in mean trabecular orientation were detected. Decreased values of trabecular spatial density and of both obsteoblastic activity and trabecular cross-sectional area noted in collateral researches suggest decreased modeling activity under weightlessness.

Assessment of jawbone trabecular bone structure amongst osteoporotic women by cone-beam computed tomography: the OSTEOSYR project.

PubMed

Barngkgei, Imad; Al Haffar, Iyad; Shaarani, Eyad; Khattab, Razan; Mashlah, Ammar

2016-11-01

To assess the trabecular bone structure of jawbones and the dens (the odontoid process of the second cervical vertebra) amongst osteoporotic and nonosteoporotic women using cone-beam computed tomography (CBCT). Analysis of the dens trabecular bone structure aimed to test the validity of CBCT in such analysis. Thirty-eight women who went under dual-energy X-ray absorptiometry (DXA) examination were scanned by CBCT. Cuboids from different areas of jawbones and the dens were extracted from each scan. Trabecular thickness (Tb.Th), trabecular separation (Tb.S), bone volume fraction (BV/TV), specific bone surface (BS/TV) and connectivity density were calculated. Student's t-test, Pearson correlation, and logistic regression analysis were used to explore differences in these measures between groups. Jawbone-derived measures showed insignificant differences (P > 0.05) between osteoporotic and non-osteoporotic groups, and weak correlations with femoral neck and lumbar vertebrae T-scores (r ≤ 0.4). Dens-derived measures, however, resulted in the opposite (r = 0.34-0.38 [P value = 0.02-0.036] and r = 0.48-0.61 [P value ≤ 0.003]) and the highest accuracy of osteoporosis prediction: 84.2% and 78.9% respectively. Trabecular bone structure of the mandible and maxilla is not affected in osteoporosis as assessed by CBCT. Dens trabecular bone analysis revealed the opposite, so some trabecular bone measures may be assessed by CBCT, which may aid in predicting osteoporosis. © 2015 Wiley Publishing Asia Pty Ltd.

The development of inter-strain variation in cortical and trabecular traits during growth of the mouse lumbar vertebral body.

PubMed

Ramcharan, M A; Faillace, M E; Guengerich, Z; Williams, V A; Jepsen, K J

2017-03-01

How cortical and trabecular bone co-develop to establish a mechanically functional structure is not well understood. Comparing early postnatal differences in morphology of lumbar vertebral bodies for three inbred mouse strains identified coordinated changes within and between cortical and trabecular traits. These early coordinate changes defined the phenotypic differences among the inbred mouse strains. Age-related changes in cortical and trabecular traits have been well studied; however, very little is known about how these bone tissues co-develop from day 1 of postnatal growth to establish functional structures by adulthood. In this study, we aimed to establish how cortical and trabecular tissues within the lumbar vertebral body change during growth for three inbred mouse strains that express wide variation in adult bone structure and function. Bone traits were quantified for lumbar vertebral bodies of female A/J, C57BL/6J (B6), and C3H/HeJ (C3H) inbred mouse strains from 1 to 105 days of age (n = 6-10 mice/age/strain). Inter-strain differences in external bone size were observed as early as 1 day of age. Reciprocal and rapid changes in the trabecular bone volume fraction and alignment in the direction of axial compression were observed by 7 days of age. Importantly, the inter-strain difference in adult trabecular bone volume fraction was established by 7 days of age. Early variation in external bone size and trabecular architecture was followed by progressive increases in cortical area between 28 and 105 days of age, with the greatest increases in cortical area seen in the mouse strain with the lowest trabecular mass. Establishing the temporal changes in bone morphology for three inbred mouse strains revealed that genetic variation in adult trabecular traits were established early in postnatal development. Early variation in trabecular architecture preceded strain-specific increases in cortical area and changes in cortical thickness. This study

Intraoperative optical coherence tomography and ab interno trabecular meshwork surgery with the Trabectome

PubMed Central

Junker, Bernd; Jordan, Jens F; Framme, Carsten; Pielen, Amelie

2017-01-01

Importance This study is the first description of the use of the intraoperative optical coherence tomography (iOCT) for trabecular meshwork surgery with the Trabectome in a regular clinical setting. Background The aim of this study is to evaluate intraoperatively the immediate success of ab interno trabeculotomy with the Trabectome defined as a removal of the trabecular meshwork. Design This is a retrospective clinical study performed in the University Eye Hospital, Medical School Hannover. Participants A total of nine consecutive Caucasian patients suffering from primary open angle glaucoma, pigment dispersion glaucoma, or pseudoexfoliation glaucoma took part in the study. Methods All patients underwent ab interno trabeculotomy surgery with the Trabectome using a commercially available iOCT to visualize the anterior chamber angle (ACA) before and after the procedure. The visualization was done using a modified Swan-Jacobs lens (all nine patients) or without lens (view from above, five patients). Main outcome measures The main outcome of this study is the success of visualization of the ACA on iOCT, especially the postprocedural visualization of the wound gap after removal of the trabecular meshwork. Results Using the view from above, the ACA could be visualized before and after the procedure in only two of the five cases. Using the modified Swan-Jacobs lens, the ACA could be visualized before the procedure and the trabecular meshwork opening after the procedure in all nine patients. Conclusion The iOCT can be used to objectify the immediate success of the surgical procedure, ie, the removal of the trabecular meshwork, of ab interno trabeculotomy with the Trabectome. The procedure itself cannot be captured sufficiently via iOCT. PMID:29026286

Running exercise alleviates trabecular bone loss and osteopenia in hemizygous β-globin knockout thalassemic mice.

PubMed

Thongchote, Kanogwun; Svasti, Saovaros; Teerapornpuntakit, Jarinthorn; Krishnamra, Nateetip; Charoenphandhu, Narattaphol

2014-06-15

A marked decrease in β-globin production led to β-thalassemia, a hereditary anemic disease associated with bone marrow expansion, bone erosion, and osteoporosis. Herein, we aimed to investigate changes in bone mineral density (BMD) and trabecular microstructure in hemizygous β-globin knockout thalassemic (BKO) mice and to determine whether endurance running (60 min/day, 5 days/wk for 12 wk in running wheels) could effectively alleviate bone loss in BKO mice. Both male and female BKO mice (1-2 mo old) showed growth retardation as indicated by smaller body weight and femoral length than their wild-type littermates. A decrease in BMD was more severe in female than in male BKO mice. Bone histomorphometry revealed that BKO mice had decreases in trabecular bone volume, trabecular number, and trabecular thickness, presumably due to suppression of osteoblast-mediated bone formation and activation of osteoclast-mediated bone resorption, the latter of which was consistent with elevated serum levels of osteoclastogenic cytokines IL-1α and -1β. As determined by peripheral quantitative computed tomography, running increased cortical density and thickness in the femoral and tibial diaphyses of BKO mice compared with those of sedentary BKO mice. Several histomorphometric parameters suggested an enhancement of bone formation (e.g., increased mineral apposition rate) and suppression of bone resorption (e.g., decreased osteoclast surface), which led to increases in trabecular bone volume and trabecular thickness in running BKO mice. In conclusion, BKO mice exhibited pervasive osteopenia and impaired bone microstructure, whereas running exercise appeared to be an effective intervention in alleviating bone microstructural defect in β-thalassemia. Copyright © 2014 the American Physiological Society.

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

PubMed Central

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

2016-01-01

Development of osteoarthritis commonly involves degeneration of epiphyseal trabecular bone. In previous studies, we observed 30–44% loss of epiphyseal trabecular bone (BV/TV) from the distal femur within one week following non-invasive knee injury in mice. Mechanical unloading (disuse) may contribute to this bone loss, however it is unclear to what extent the injured limb is unloaded following injury, and whether disuse can fully account for the observed magnitude of bone loss. In this study, we investigated the contribution of mechanical unloading to trabecular bone changes observed following non-invasive knee injury in mice (female C57BL/6N). We investigated changes in gait during treadmill walking, and changes in voluntary activity level using Open Field analysis at 4, 14, 28, and 42 days post-injury. We also quantified epiphyseal trabecular bone using μCT and weighed lower-limb muscles to quantify atrophy following knee injury in both ground control and hindlimb unloaded (HLU) mice. Gait analysis revealed a slightly altered stride pattern in the injured limb, with a decreased stance phase and increased swing phase. However, Open Field analysis revealed no differences in voluntary movement between injured and sham mice at any time point. Both knee injury and HLU resulted in comparable magnitudes of trabecular bone loss, however HLU resulted in considerably more muscle loss than knee injury, suggesting another mechanism contributing to bone loss following injury. Altogether, these data suggest that mechanical unloading likely contributes to trabecular bone loss following non-invasive knee injury, but the magnitude of this bone loss cannot be fully explained by disuse. PMID:26826014

Mandibular trabecular bone as fracture indicator in 80-year-old men and women.

PubMed

Hassani-Nejad, Azar; Ahlqwist, Margareta; Hakeberg, Magnus; Jonasson, Grethe

2013-12-01

The objective of the present study was to compare assessments of the mandibular bone as fracture risk indicators for 277 men and women. The mandibular trabecular bone was evaluated in periapical radiographs, using a visual index, as dense, mixed dense and sparse, or sparse. Bone texture was analysed using a computer-based method in which the number of transitions from trabeculae to intertrabecular spaces was calculated. The sum of the sizes and intensities of the spaces between the trabeculae was calculated using Jaw-X software. Women had a statistically significantly greater number of fractures and a higher frequency of sparse mandibular bone. The OR for having suffered a fracture with visually sparse trabecular bone was highest for the male group (OR = 5.55) and lowest for the female group (OR = 3.35). For bone texture as an indicator of previous fracture, the OR was significant for the female group (OR = 2.61) but not for the male group, whereas the Jaw-X calculations did not differentiate between fractured and non-fractured groups. In conclusion, all bone-quality assessments showed that women had a higher incidence of sparse trabecular bone than did men. Only the methods of visual assessment and trabecular texture were significantly correlated with previous bone fractures. © 2013 Eur J Oral Sci.

Fabrication of Trabecular Bone-Templated Tissue-Engineered Constructs by 3D Inkjet Printing.

PubMed

Vanderburgh, Joseph P; Fernando, Shanik J; Merkel, Alyssa R; Sterling, Julie A; Guelcher, Scott A

2017-11-01

3D printing enables the creation of scaffolds with precisely controlled morphometric properties for multiple tissue types, including musculoskeletal tissues such as cartilage and bone. Computed tomography (CT) imaging has been combined with 3D printing to fabricate anatomically scaled patient-specific scaffolds for bone regeneration. However, anatomically scaled scaffolds typically lack sufficient resolution to recapitulate the <100 micrometer-scale trabecular architecture essential for investigating the cellular response to the morphometric properties of bone. In this study, it is hypothesized that the architecture of trabecular bone regulates osteoblast differentiation and mineralization. To test this hypothesis, human bone-templated 3D constructs are fabricated via a new micro-CT/3D inkjet printing process. It is shown that this process reproducibly fabricates bone-templated constructs that recapitulate the anatomic site-specific morphometric properties of trabecular bone. A significant correlation is observed between the structure model index (a morphometric parameter related to surface curvature) and the degree of mineralization of human mesenchymal stem cells, with more concave surfaces promoting more extensive osteoblast differentiation and mineralization compared to predominately convex surfaces. These findings highlight the significant effects of trabecular architecture on osteoblast function. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A comparative study of a preservative-free latanoprost cationic emulsion (Catioprost) and a BAK-preserved latanoprost solution in animal models.

PubMed

Daull, Philippe; Buggage, Ronald; Lambert, Grégory; Faure, Marie-Odile; Serle, Janet; Wang, Rong-Fang; Garrigue, Jean-Sébastien

2012-10-01

Benzalkonium chloride (BAK), a common preservative in eye drops, can induce ocular surface toxicity that may decrease glaucoma therapy compliance. The ocular hypotensive effect, pharmacokinetic (PK) profiles, and local tolerance of a preservative-free latanoprost 0.005% cationic emulsion (Catioprost(®)), and a BAK-preserved latanoprost 0.005% solution (Xalatan(®)), were compared. The ocular hypotensive effect was evaluated in monkeys with elevated intraocular pressure (IOP) induced by laser photocoagulation of the trabecular meshwork. Each monkey (n=8) received both latanoprost formulations once daily for 5 consecutive treatment days in a crossover design with at least a 2-week washout period between treatments. IOP was measured at baseline (on day 1, no instillation), on vehicle treatment day (day 0), and on treatment days 1, 3, and 5 before drug instillation and then hourly for 6 h. In rabbits, the ocular and systemic concentrations of latanoprost free acid were determined following a single instillation and the local tolerance of twice daily instillations over 28 days was assessed. Both the preservative-free and BAK-preserved latanoprost formulations shared the same efficacy profile with the maximum IOP reduction occurring 2 h after each morning dose (-15%, -20%, and -26%; -15%, -23%, and -23% on days 1, 3, and 5, respectively) and lasting through 24 h. The equivalence in efficacy was confirmed by the PK data demonstrating similar area under the curves (AUCs). While both formulations were well tolerated, the incidence of conjunctival hyperemia was reduced by 42% with the BAK-free latanoprost cationic emulsion. In animal models, a preservative-free latanoprost cationic emulsion was as effective as Xalatan(®) for lowering IOP with an improved ocular tolerance profile.

Variability of morphometric parameters of human trabecular tissue from coxo-arthritis and osteoporotic samples.

PubMed

Marinozzi, Franco; Marinozzi, Andrea; Bini, Fabiano; Zuppante, Francesca; Pecci, Raffaella; Bedini, Rossella

2012-01-01

Morphometric and architectural bone parameters change in diseases such as osteoarthritis and osteoporosis. The mechanical strength of bone is primarily influenced by bone quantity and quality. Bone quality is defined by parameters such as trabecular thickness, trabecular separation, trabecular density and degree of anisotropy that describe the micro-architectural structure of bone. Recently, many studies have validated microtomography as a valuable investigative technique to assess bone morphometry, thanks to micro-CT non-destructive, non-invasive and reliability features, in comparison to traditional techniques such as histology. The aim of this study is the analysis by micro-computed tomography of six specimens, extracted from patients affected by osteoarthritis and osteoporosis, in order to observe the tridimensional structure and calculate several morphometric parameters.

Menstrual state and exercise as determinants of spinal trabecular bone density in female athletes.

PubMed Central

Wolman, R L; Clark, P; McNally, E; Harries, M; Reeve, J

1990-01-01

OBJECTIVE--To study the effects of amenorrhoea and intensive back exercise on the bone mineral density of the lumbar spine in female athletes. DESIGN--Cross sectional study comparing amenorrhoeic with eumenorrhoeic athletes and rowers with non-rowers. SETTING--The British Olympic Medical Centre, Northwick Park Hospital. PATIENTS--46 Elite female athletes comprising 19 rowers, 18 runners, and nine dancers, of whom 25 were amenorrhoeic and 21 eumenorrhoeic. MAIN OUTCOME MEASURE--Trabecular bone mineral density of the lumbar spine measured by computed tomography. RESULTS--Mean trabecular bone mineral density was 42 mg/cm3 (95% confidence interval 22 to 62 mg/cm3) lower in the amenorrhoeic than the eumenorrhoeic athletes; this difference was highly significant (p = 0.0002). Mean trabecular bone mineral density was 21 mg/cm3 (1 to 41 mg/cm3) lower in the non-rowers than the rowers; this was also significant (p = 0.05). There was no interaction between these two effects (p = 0.28). CONCLUSION--The effect of intensive exercise on the lumbar spine partially compensates for the adverse effect of amenorrhoea on spinal trabecular bone density. Images p516-a PMID:2207417

Validation of calcaneus trabecular microstructure measurements by HR-pQCT.

PubMed

Metcalf, Louis M; Dall'Ara, Enrico; Paggiosi, Margaret A; Rochester, John R; Vilayphiou, Nicolas; Kemp, Graham J; McCloskey, Eugene V

2018-01-01

Assessment of calcaneus microstructure using high-resolution peripheral quantitative computed tomography (HR-pQCT) might be used to improve fracture risk predictions or to assess responses to pharmacological and physical interventions. To develop a standard clinical protocol for the calcaneus, we validated calcaneus trabecular microstructure measured by HR-pQCT against 'gold-standard' micro-CT measurements. Ten human cadaveric feet were scanned in situ using HR-pQCT (isotropic 82μm voxel size) at 100, 150 and 200ms integration times, and at 100ms integration time following removal of the calcaneus from the foot (ex vivo). Dissected portions of these bones were scanned using micro-computed tomography (micro-CT) at an isotropic 17.4μm voxel size. HR-pQCT images were rigidly registered to those obtained with micro-CT and divided into multiple 5mm sided cubes to evaluate and compare morphometric parameters between the modalities. Standard HR-pQCT measurements (derived bone volume fraction (BV/TV d ); trabecular number, Tb.N; derived trabecular thickness, Tb.Th d ; derived trabecular spacing, Tb.Sp d ) and corresponding micro-CT voxel-based measurements (BV/TV, Tb.N, Tb.Th, Tb.Sp) were compared. A total of 108 regions of interest were analysed across the 10 specimens. At all integration times HR-pQCT BV/TV d was strongly correlated with micro-CT BV/TV (r 2 =0.95-0.98, RMSE=1%), but BV/TV d was systematically lower than that measured by micro-CT (mean bias=5%). In contrast, HR-pQCT systematically overestimated Tb.N at all integration times; of the in situ scans, 200ms yielded the lowest mean bias and the strongest correlation with micro-CT (r 2 =0.61, RMSE=0.15mm -1 ). Regional analysis revealed greater accuracy for Tb.N in the superior regions of the calcaneus at all integration times in situ (mean bias=0.44-0.85mm -1 ; r 2 =0.70-0.88, p<0.001 versus mean bias=0.63-1.46mm -1 ; r 2 ≤0.08, p≥0.21 for inferior regions). Tb.Sp d was underestimated by HR-pQCT compared

Curcumin reduces trabecular and cortical bone in naive and lewis lung carcinoma-bearing mice.

PubMed

Yan, Lin; Yee, John A; Cao, Jay

2013-08-01

The present study investigated the effects of curcumin on bone microstructure in non-tumor-bearing and Lewis lung carcinoma-(LLC)-bearing female C57BL/6 mice. Morphometric analysis showed that dietary supplementation with curcumin (2% or 4%) significantly reduced the bone volume to total volume ratio, connectivity density and trabecular number, and significantly increased the structure model index (an indicator of the plate- and rod-like geometry of trabecular structure) and trabecular separation in vertebral bodies compared to controls in both non-tumor-bearing and LLC-bearing mice. Similar changes in trabecular bone were observed in the femoral bone in curcumin-fed mice. Curcumin significantly reduced the cortical bone area to total area ratio and cortical thickness in femoral mid-shaft, but not in vertebral bodies, in both non-tumor-bearing and LLC-bearing mice. Curcumin feeding reduced plasma concentrations of osteocalcin and increased tartrate-resistant acid phosphate 5b in mice regardless of the presence of LLC, indicating that curcumin disrupts the balance of bone remodeling. Our results demonstrated that curcumin reduced the trabecular bone volume and cortical bone density. The skeleton is a favored site of metastasis for many types of cancers, and curcumin has been investigated in clinical trials in patients with cancer for its chemopreventive effects. Our results suggest the possibility of a combined effect of cancer-induced osteolysis and curcumin-stimulated bone loss in patients using curcumin. The assessment of bone structural changes should be considered for those who participate in curcumin clinical trials to determine its effects on skeleton health, particularly for those with advanced malignancies.

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

PubMed

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

2016-10-01

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

Quantitative imaging of peripheral trabecular bone microarchitecture using MDCT.

PubMed

Chen, Cheng; Zhang, Xiaoliu; Guo, Junfeng; Jin, Dakai; Letuchy, Elena M; Burns, Trudy L; Levy, Steven M; Hoffman, Eric A; Saha, Punam K

2018-01-01

Osteoporosis associated with reduced bone mineral density (BMD) and microarchitectural changes puts patients at an elevated risk of fracture. Modern multidetector row CT (MDCT) technology, producing high spatial resolution at increasingly lower dose radiation, is emerging as a viable modality for trabecular bone (Tb) imaging. Wide variation in CT scanners raises concerns of data uniformity in multisite and longitudinal studies. A comprehensive cadaveric study was performed to evaluate MDCT-derived Tb microarchitectural measures. A human pilot study was performed comparing continuity of Tb measures estimated from two MDCT scanners with significantly different image resolution features. Micro-CT imaging of cadaveric ankle specimens (n=25) was used to examine the validity of MDCT-derived Tb microarchitectural measures. Repeat scan reproducibility of MDCT-based Tb measures and their ability to predict mechanical properties were examined. To assess multiscanner data continuity of Tb measures, the distal tibias of 20 volunteers (age:26.2±4.5Y,10F) were scanned using the Siemens SOMATOM Definition Flash and the higher resolution Siemens SOMATOM Force scanners with an average 45-day time gap between scans. The correlation of Tb measures derived from the two scanners over 30% and 60% peel regions at the 4% to 8% of distal tibia was analyzed. MDCT-based Tb measures characterizing bone network area density, plate-rod microarchitecture, and transverse trabeculae showed good correlations (r∈0.85,0.92) with the gold standard micro-CT-derived values of matching Tb measures. However, other MDCT-derived Tb measures characterizing trabecular thickness and separation, erosion index, and structure model index produced weak correlation (r<0.8) with their micro-CT-derived values. Most MDCT Tb measures were found repeatable (ICC∈0.94,0.98). The Tb plate-width measure showed a strong correlation (r = 0.89) with experimental yield stress, while the transverse trabecular measure

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

PubMed

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

2002-02-01

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

Differences in trabecular bone of leptin-deficient ob/ob mice in response to biomechanical loading.

PubMed

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

2008-06-15

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

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

PubMed

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

2015-10-01

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

The robustness of T2 value as a trabecular structural index at multiple spatial resolutions of 7 Tesla MRI.

PubMed

Lee, D K; Song, Y K; Park, B W; Cho, H P; Yeom, J S; Cho, G; Cho, H

2018-04-15

To evaluate the robustness of MR transverse relaxation times of trabecular bone from spin-echo and gradient-echo acquisitions at multiple spatial resolutions of 7 T. The effects of MRI resolutions to T 2 and T2* of trabecular bone were numerically evaluated by Monte Carlo simulations. T 2 , T2*, and trabecular structural indices from multislice multi-echo and UTE acquisitions were measured in defatted human distal femoral condyles on a 7 T scanner. Reference structural indices were extracted from high-resolution microcomputed tomography images. For bovine knee trabecular samples with intact bone marrow, T 2 and T2* were measured by degrading spatial resolutions on a 7 T system. In the defatted trabecular experiment, both T 2 and T2* values showed strong ( |r| > 0.80) correlations with trabecular spacing and number, at a high spatial resolution of 125 µm 3 . The correlations for MR image-segmentation-derived structural indices were significantly degraded ( |r| < 0.50) at spatial resolutions of 250 and 500 µm 3 . The correlations for T2* rapidly dropped ( |r| < 0.50) at a spatial resolution of 500 µm 3 , whereas those for T 2 remained consistently high ( |r| > 0.85). In the bovine trabecular experiments with intact marrow, low-resolution (approximately 1 mm 3 , 2 minutes) T 2 values did not shorten ( |r| > 0.95 with respect to approximately 0.4 mm 3 , 11 minutes) and maintained consistent correlations ( |r| > 0.70) with respect to trabecular spacing (turbo spin echo, 22.5 minutes). T 2 measurements of trabeculae at 7 T are robust with degrading spatial resolution and may be preferable in assessing trabecular spacing index with reduced scan time, when high-resolution 3D micro-MRI is difficult to obtain. © 2018 International Society for Magnetic Resonance in Medicine.

Cortical Bone Morphological and Trabecular Bone Microarchitectural Changes in the Mandible and Femoral Neck of Ovariectomized Rats

PubMed Central

Hsu, Pei-Yu; Tsai, Ming-Tzu; Wang, Shun-Ping; Chen, Ying-Ju; Wu, Jay; Hsu, Jui-Ting

2016-01-01

Objective This study used microcomputed tomography (micro-CT) to evaluate the effects of ovariectomy on the trabecular bone microarchitecture and cortical bone morphology in the femoral neck and mandible of female rats. Materials and Methods Twelve female Wister rats were divided into two groups: the control and ovariectomized groups. The rats in the ovariectomized group received ovariectomy at 8 weeks of age; all the rats were sacrificed at 20 weeks of age, and their mandibles and femurs were removed and scanned using micro-CT. Four microstructural trabecular bone parameters were measured for the region below the first mandibular molar and the femoral neck region: bone volume fraction (BV/TV), trabecular thickness (TbTh), trabecular separation (TbSp), and trabecular number (TbN). In addition, four cortical bone parameters were measured for the femoral neck region: total cross-sectional area (TtAr), cortical area (CtAr), cortical bone area fraction (CtAr/TtAr), and cortical thickness (CtTh). The CtTh at the masseteric ridge was used to assess the cortical bone morphology in the mandible. The trabecular bone microarchitecture and cortical bone morphology in the femoral necks and mandibles of the control group were compared with those of the ovariectomized group. Furthermore, Spearman’s correlation (rs) was conducted to analyze the correlation between the osteoporosis conditions of the mandible and femoral neck. Results Regarding the trabecular bone microarchitectural parameters, the BV/TV of the trabecular bone microarchitecture in the femoral necks of the control group (61.199±11.288%, median ± interquartile range) was significantly greater than that of the ovariectomized group (40.329±5.153%). Similarly, the BV/TV of the trabecular bone microarchitecture in the mandibles of the control group (51.704±6.253%) was significantly greater than that of the ovariectomized group (38.486±9.111%). Furthermore, the TbSp of the femoral necks in the ovariectomized group

Fractal analysis of mandibular trabecular bone: optimal tile sizes for the tile counting method.

PubMed

Huh, Kyung-Hoe; Baik, Jee-Seon; Yi, Won-Jin; Heo, Min-Suk; Lee, Sam-Sun; Choi, Soon-Chul; Lee, Sun-Bok; Lee, Seung-Pyo

2011-06-01

This study was performed to determine the optimal tile size for the fractal dimension of the mandibular trabecular bone using a tile counting method. Digital intraoral radiographic images were obtained at the mandibular angle, molar, premolar, and incisor regions of 29 human dry mandibles. After preprocessing, the parameters representing morphometric characteristics of the trabecular bone were calculated. The fractal dimensions of the processed images were analyzed in various tile sizes by the tile counting method. The optimal range of tile size was 0.132 mm to 0.396 mm for the fractal dimension using the tile counting method. The sizes were closely related to the morphometric parameters. The fractal dimension of mandibular trabecular bone, as calculated with the tile counting method, can be best characterized with a range of tile sizes from 0.132 to 0.396 mm.

Phenotypic integration among trabecular and cortical bone traits establishes mechanical functionality of inbred mouse vertebrae.

PubMed

Tommasini, Steven M; Hu, Bin; Nadeau, Joseph H; Jepsen, Karl J

2009-04-01

Conventional approaches to identifying quantitative trait loci (QTLs) regulating bone mass and fragility are limited because they examine cortical and trabecular traits independently. Prior work examining long bones from young adult mice and humans indicated that skeletal traits are functionally related and that compensatory interactions among morphological and compositional traits are critical for establishing mechanical function. However, it is not known whether trait covariation (i.e., phenotypic integration) also is important for establishing mechanical function in more complex, corticocancellous structures. Covariation among trabecular, cortical, and compositional bone traits was examined in the context of mechanical functionality for L(4) vertebral bodies across a panel of 16-wk-old female AXB/BXA recombinant inbred (RI) mouse strains. The unique pattern of randomization of the A/J and C57BL/6J (B6) genome among the RI panel provides a powerful tool that can be used to measure the tendency for different traits to covary and to study the biology of complex traits. We tested the hypothesis that genetic variants affecting vertebral size and mass are buffered by changes in the relative amounts of cortical and trabecular bone and overall mineralization. Despite inheriting random sets of A/J and B6 genomes, the RI strains inherited nonrandom sets of cortical and trabecular bone traits. Path analysis, which is a multivariate analysis that shows how multiple traits covary simultaneously when confounding variables like body size are taken into consideration, showed that RI strains that tended to have smaller vertebrae relative to body size achieved mechanical functionality by increasing mineralization and the relative amounts of cortical and trabecular bone. The interdependence among corticocancellous traits in the vertebral body indicated that variation in trabecular bone traits among inbred mouse strains, which is often thought to arise from genetic factors, is also

Fractal analysis of mandibular trabecular bone: optimal tile sizes for the tile counting method

PubMed Central

Huh, Kyung-Hoe; Baik, Jee-Seon; Heo, Min-Suk; Lee, Sam-Sun; Choi, Soon-Chul; Lee, Sun-Bok; Lee, Seung-Pyo

2011-01-01

Purpose This study was performed to determine the optimal tile size for the fractal dimension of the mandibular trabecular bone using a tile counting method. Materials and Methods Digital intraoral radiographic images were obtained at the mandibular angle, molar, premolar, and incisor regions of 29 human dry mandibles. After preprocessing, the parameters representing morphometric characteristics of the trabecular bone were calculated. The fractal dimensions of the processed images were analyzed in various tile sizes by the tile counting method. Results The optimal range of tile size was 0.132 mm to 0.396 mm for the fractal dimension using the tile counting method. The sizes were closely related to the morphometric parameters. Conclusion The fractal dimension of mandibular trabecular bone, as calculated with the tile counting method, can be best characterized with a range of tile sizes from 0.132 to 0.396 mm. PMID:21977478

Relationships of the phase velocity with the microarchitectural parameters in bovine trabecular bone in vitro: Application of a stratified model

NASA Astrophysics Data System (ADS)

Lee, Kang Il

2012-08-01

The present study aims to provide insight into the relationships of the phase velocity with the microarchitectural parameters in bovine trabecular bone in vitro. The frequency-dependent phase velocity was measured in 22 bovine femoral trabecular bone samples by using a pair of transducers with a diameter of 25.4 mm and a center frequency of 0.5 MHz. The phase velocity exhibited positive correlation coefficients of 0.48 and 0.32 with the ratio of bone volume to total volume and the trabecular thickness, respectively, but a negative correlation coefficient of -0.62 with the trabecular separation. The best univariate predictor of the phase velocity was the trabecular separation, yielding an adjusted squared correlation coefficient of 0.36. The multivariate regression models yielded adjusted squared correlation coefficients of 0.21-0.36. The theoretical phase velocity predicted by using a stratified model for wave propagation in periodically stratified media consisting of alternating parallel solid-fluid layers showed reasonable agreements with the experimental measurements.

[Is there a relation between weight in rats, bone density, ash weight and histomorphometric indicators of trabecular volume and thickness in the bones of extremities?].

PubMed

Zák, J; Kapitola, J; Povýsil, C

2003-01-01

Authors deal with question, if there is possibility to infer bone histological structure (described by histomorphometric parameters of trabecular bone volume and trabecular thickness) from bone density, ash weight or even from weight of animal (rat). Both tibias of each of 30 intact male rats, 90 days old, were processed. Left tibia was utilized to the determination of histomorphometric parameters of undecalcified bone tissue patterns by automatic image analysis. Right tibia was used to the determination of values of bone density, using Archimedes' principle. Values of bone density, ash weight, ash weight related to bone volume and animal weight were correlated with histomorphometric parameters (trabecular bone volume, trabecular thickness) by Pearson's correlation test. One could presume the existence of relation between data, describing bone mass at the histological level (trabecular bone of tibia) and other data, describing mass of whole bone or even animal mass (weight). But no statistically significant correlation was found. The reason of the present results could be in the deviations of trabecular density in marrow of tibia. Because of higher trabecular bone density in metaphyseal and epiphyseal regions, the histomorphometric analysis of trabecular bone is preferentially done in these areas. It is possible, that this irregularity of trabecular tibial density could be the source of the deviations, which could influence the results of correlations determined. The values of bone density, ash weight and animal weight do not influence trabecular bone volume and vice versa: static histomorphometric parameters of trabecular bone do not reflect bone density, ash weight and weight of animal.

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

PubMed Central

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

2008-01-01

Purpose To describe the 1-year success of a trabecular stent implant in a pseudophakic glaucoma patient. The stent is implanted through a small corneal incision under gonioscopic control. Intraocular pressure control was reported in cultured human anterior segment. Design Observational case report. Methods We report the case of a patient who was implanted and followed-up for 1 year at the Dipartimento di Fisiopatologia Clinica. The main outcome measures were intraocular pressure and visual field. Results The patient’s intraocular pressure was controlled with topical beta-blockers for 6 months and without therapy for 6 months. Two diurnal curves demonstrated achievement of target pressure during the day. The 1-year visual field was unchanged. Conclusions We are not aware of previous reports of trabecular stent implantation in pseudophakic patients. The trabecular stent had minimal peri-operative morbidity. Identification of the implantation site is challenging and reduction of efficacy over time may occur. PMID:19668446

Single dose of bisphosphonate preserves gains in bone mass following cessation of sclerostin antibody in Brtl/+ osteogenesis imperfecta model.

PubMed

Perosky, Joseph E; Khoury, Basma M; Jenks, Terese N; Ward, Ferrous S; Cortright, Kai; Meyer, Bethany; Barton, David K; Sinder, Benjamin P; Marini, Joan C; Caird, Michelle S; Kozloff, Kenneth M

2016-12-01

Sclerostin antibody has demonstrated a bone-forming effect in pre-clinical models of osteogenesis imperfecta, where mutations in collagen or collagen-associated proteins often result in high bone fragility in pediatric patients. Cessation studies in osteoporotic patients have demonstrated that sclerostin antibody, like intermittent PTH treatment, requires sequential anti-resorptive therapy to preserve the anabolic effects in adult populations. However, the persistence of anabolic gains from either drug has not been explored clinically in OI, or in any animal model. To determine whether cessation of sclerostin antibody therapy in a growing OI skeleton requires sequential anti-resorptive treatment to preserve anabolic gains in bone mass, we treated 3week old Brtl/+ and wild type mice for 5weeks with SclAb, and then withdrew treatment for an additional 6weeks. Trabecular bone loss was evident following cessation, but was preserved in a dose-dependent manner with single administration of pamidronate at the time of cessation. In vivo longitudinal near-infrared optical imaging of cathepsin K activation in the proximal tibia suggests an anti-resorptive effect of both SclAb and pamidronate which is reversed after three weeks of cessation. Cortical bone was considerably less susceptible to cessation effects, and showed no structural or functional deficits in the absence of pamidronate during this cessation period. In conclusion, while SclAb induces a considerable anabolic gain in the rapidly growing Brtl/+ murine model of OI, a single sequential dose of antiresorptive drug is required to maintain bone mass at trabecular sites for 6weeks following cessation. Copyright © 2016 Elsevier Inc. All rights reserved.

Fractal dimension of trabecular bone projection texture is related to three-dimensional microarchitecture.

PubMed

Pothuaud, L; Benhamou, C L; Porion, P; Lespessailles, E; Harba, R; Levitz, P

2000-04-01

The purpose of this work was to understand how fractal dimension of two-dimensional (2D) trabecular bone projection images could be related to three-dimensional (3D) trabecular bone properties such as porosity or connectivity. Two alteration processes were applied to trabecular bone images obtained by magnetic resonance imaging: a trabeculae dilation process and a trabeculae removal process. The trabeculae dilation process was applied from the 3D skeleton graph to the 3D initial structure with constant connectivity. The trabeculae removal process was applied from the initial structure to an altered structure having 99% of porosity, in which both porosity and connectivity were modified during this second process. Gray-level projection images of each of the altered structures were simply obtained by summation of voxels, and fractal dimension (Df) was calculated. Porosity (phi) and connectivity per unit volume (Cv) were calculated from the 3D structure. Significant relationships were found between Df, phi, and Cv. Df values increased when porosity increased (dilation and removal processes) and when connectivity decreased (only removal process). These variations were in accordance with all previous clinical studies, suggesting that fractal evaluation of trabecular bone projection has real meaning in terms of porosity and connectivity of the 3D architecture. Furthermore, there was a statistically significant linear dependence between Df and Cv when phi remained constant. Porosity is directly related to bone mineral density and fractal dimension can be easily evaluated in clinical routine. These two parameters could be associated to evaluate the connectivity of the structure.

Effects of different loading patterns on the trabecular bone morphology of the proximal femur using adaptive bone remodeling.

PubMed

Banijamali, S Mohammad Ali; Oftadeh, Ramin; Nazarian, Ara; Goebel, Ruben; Vaziri, Ashkan; Nayeb-Hashemi, Hamid

2015-01-01

In this study, the changes in the bone density of human femur model as a result of different loadings were investigated. The model initially consisted of a solid shell representing cortical bone encompassing a cubical network of interconnected rods representing trabecular bone. A computationally efficient program was developed that iteratively changed the structure of trabecular bone by keeping the local stress in the structure within a defined stress range. The stress was controlled by either enhancing existing beam elements or removing beams from the initial trabecular frame structure. Analyses were performed for two cases of homogenous isotropic and transversely isotropic beams.Trabecular bone structure was obtained for three load cases: walking, stair climbing and stumbling without falling. The results indicate that trabecular bone tissue material properties do not have a significant effect on the converged structure of trabecular bone. In addition, as the magnitude of the loads increase, the internal structure becomes denser in critical zones. Loading associated with the stumbling results in the highest density;whereas walking, considered as a routine daily activity, results in the least internal density in different regions. Furthermore, bone volume fraction at the critical regions of the converged structure is in good agreement with previously measured data obtained from combinations of dual X-ray absorptiometry (DXA) and computed tomography (CT). The results indicate that the converged bone architecture consisting of rods and plates are consistent with the natural bone morphology of the femur. The proposed model shows a promising means to understand the effects of different individual loading patterns on the bone density.

Different osteochondral potential of clonal cell lines derived from adult human trabecular bone.

PubMed

Osyczka, Anna M; Nöth, Ulrich; Danielson, Keith G; Tuan, Rocky S

2002-06-01

Cells derived from human trabecular bones have been shown to have multipotential differentiation ability along osteogenic, chondrogenic, and adipogenic lineages. In this study, we have derived two clonal sublines of human trabecular bone cells by means of stable transduction with human papilloma virus E6/E7 genes. Our results showed that these clonal sublines differ in their osteochondral potential, but are equally adipogenic, indicative of the heterogeneous nature of the parental cell population. The availability of these cell lines should be useful for the analysis of the mechanisms regulating the differentiation of adult mesenchymal progenitor cells.

Vertebral body bone strength: the contribution of individual trabecular element morphology.

PubMed

Parkinson, I H; Badiei, A; Stauber, M; Codrington, J; Müller, R; Fazzalari, N L

2012-07-01

Although the amount of bone explains the largest amount of variability in bone strength, there is still a significant proportion unaccounted for. The morphology of individual bone trabeculae explains a further proportion of the variability in bone strength and bone elements that contribute to bone strength depending on the direction of loading. Micro-CT imaging enables measurement of bone microarchitecture and subsequently mechanical strength of the same sample. It is possible using micro-CT data to perform morphometric analysis on individual rod and plate bone trabeculae using a volumetric spatial decomposition algorithm and hence determine their contribution to bone strength. Twelve pairs of vertebral bodies (T12/L1 or L4/L5) were harvested from human cadavers, and bone cubes (10 × 10 × 10 mm) were obtained. After micro-CT imaging, a volumetric spatial decomposition algorithm was applied, and measures of individual trabecular elements were obtained. Bone strength was measured in compression, where one bone specimen from each vertebral segment was tested supero-inferiorly (SI) and the paired specimen was tested antero-posteriorly (AP). Bone volume fraction was the strongest individual determinant of SI strength (r(2) = 0.77, p < 0.0001) and AP (r(2) = 0.54, p < 0.0001). The determination of SI strength was improved to r(2) = 0.87 with the addition of mean rod length and relative plate bone volume fraction. The determination of AP strength was improved to r(2) = 0.85 with the addition of mean rod volume and relative rod bone volume fraction. Microarchitectural measures of individual trabeculae that contribute to bone strength have been identified. In addition to the contribution of BV/TV, trabecular rod morphology increased the determination of AP strength by 57%, whereas measures of trabecular plate and rod morphology increased determination of SI strength by 13%. Decomposing vertebral body bone architecture into its constituent

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

NASA Astrophysics Data System (ADS)

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

2016-07-01

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

Measurement of the normalized broadband ultrasound attenuation in trabecular bone by using a bidirectional transverse transmission technique

NASA Astrophysics Data System (ADS)

Lee, Kang Il

2015-01-01

A new method for measuring the normalized broadband ultrasound attenuation (nBUA) in trabecular bone by using a bidirectional transverse transmission technique was proposed and validated with measurements obtained by using the conventional transverse transmission technique. There was no significant difference between the nBUA measurements obtained for 14 bovine femoral trabecular bone samples by using the bidirectional and the conventional transverse transmission techniques. The nBUA measured by using the two transverse transmission techniques showed strong positive correlations of r = 0.87 to 0.88 with the apparent bone density, consistent with the behavior in human trabecular bone invitro. We expect that the new method can be usefully applied for improved accuracy and precision in clinical measurements.

Three-dimensional simulation of ultrasound propagation through trabecular bone structures measured by synchrotron microtomography.

PubMed

Bossy, Emmanuel; Padilla, Frédéric; Peyrin, Françoise; Laugier, Pascal

2005-12-07

Three-dimensional numerical simulations of ultrasound transmission were performed through 31 trabecular bone samples measured by synchrotron microtomography. The synchrotron microtomography provided high resolution 3D mappings of bone structures, which were used as the input geometry in the simulation software developed in our laboratory. While absorption (i.e. the absorption of ultrasound through dissipative mechanisms) was not taken into account in the algorithm, the simulations reproduced major phenomena observed in real through-transmission experiments in trabecular bone. The simulated attenuation (i.e. the decrease of the transmitted ultrasonic energy) varies linearly with frequency in the MHz frequency range. Both the speed of sound (SOS) and the slope of the normalized frequency-dependent attenuation (nBUA) increase with the bone volume fraction. Twenty-five out of the thirty-one samples exhibited negative velocity dispersion. One sample was rotated to align the main orientation of the trabecular structure with the direction of ultrasonic propagation, leading to the observation of a fast and a slow wave. Coupling numerical simulation with real bone architecture therefore provides a powerful tool to investigate the physics of ultrasound propagation in trabecular structures. As an illustration, comparison between results obtained on bone modelled either as a fluid or a solid structure suggested the major role of mode conversion of the incident acoustic wave to shear waves in bone to explain the large contribution of scattering to the overall attenuation.

A synchrotron radiation microtomography system for the analysis of trabecular bone samples.

PubMed

Salomé, M; Peyrin, F; Cloetens, P; Odet, C; Laval-Jeantet, A M; Baruchel, J; Spanne, P

1999-10-01

X-ray computed microtomography is particularly well suited for studying trabecular bone architecture, which requires three-dimensional (3-D) images with high spatial resolution. For this purpose, we describe a three-dimensional computed microtomography (microCT) system using synchrotron radiation, developed at ESRF. Since synchrotron radiation provides a monochromatic and high photon flux x-ray beam, it allows high resolution and a high signal-to-noise ratio imaging. The principle of the system is based on truly three-dimensional parallel tomographic acquisition. It uses a two-dimensional (2-D) CCD-based detector to record 2-D radiographs of the transmitted beam through the sample under different angles of view. The 3-D tomographic reconstruction, performed by an exact 3-D filtered backprojection algorithm, yields 3-D images with cubic voxels. The spatial resolution of the detector was experimentally measured. For the application to bone investigation, the voxel size was set to 6.65 microm, and the experimental spatial resolution was found to be 11 microm. The reconstructed linear attenuation coefficient was calibrated from hydroxyapatite phantoms. Image processing tools are being developed to extract structural parameters quantifying trabecular bone architecture from the 3-D microCT images. First results on human trabecular bone samples are presented.

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

NASA Astrophysics Data System (ADS)

Gong, He; Fan, Yubo; Zhang, Ming

2008-04-01

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

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

PubMed

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

1997-05-01

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

Dipeptidyl Peptidase-4 Inhibitor, Vildagliptin, Improves Trabecular Bone Mineral Density and Microstructure in Obese, Insulin-Resistant, Pre-diabetic Rats.

PubMed

Charoenphandhu, Narattaphol; Suntornsaratoon, Panan; Sa-Nguanmoo, Piangkwan; Tanajak, Pongpan; Teerapornpuntakit, Jarinthorn; Aeimlapa, Ratchaneevan; Chattipakorn, Nipon; Chattipakorn, Siriporn

2018-02-02

Obese insulin resistance and type 2 diabetes mellitus profoundly impair bone mechanical properties and bone quality. However, because several antidiabetes drugs, especially thiazolidinediones, further aggravate bone loss in individuals with diabetes, diabetic osteopathy should not be treated by using simply any glucose-lowering agents. Recently, incretins have been reported to affect osteoblast function positively. The present study aimed to investigate the effects of vildagliptin, an inhibitor of dipeptidyl peptidase-4, on bone of rats with high-fat-diet-induced prediabetes. Male rats were fed a high-fat diet for 12 weeks to induce obese insulin resistance and then treated with vildagliptin for 4 weeks. The effects of the drug on bone were determined by microcomputed tomography and bone histomorphometry. Vildagliptin markedly improved insulin resistance in these obese insulin-resistant rats. It also significantly increased volumetric bone mineral density. Specifically, vildagliptin-treated obese insulin-resistant rats exhibited higher trabecular volumetric bone mineral density than vehicle-treated obese insulin-resistant rats, whereas cortical volumetric bone mineral density, cortical thickness and area were not changed. Bone histomorphometric analysis in a trabecular-rich area (i.e. tibial metaphysis) revealed greater trabecular bone volume and number and less trabecular separation without change in trabecular thickness, osteocyte lacunar area or cortical thickness in the vildagliptin-treated group. Vildagliptin had a beneficial effect on the bone of obese insulin-resistant rats with prediabetes, particularly at the trabecular site. Such benefit probably results from enhanced bone formation rather than from suppressed bone resorption. Copyright © 2018 Diabetes Canada. Published by Elsevier Inc. All rights reserved.

Phase-contrast CT: Qualitative and Quantitative Evaluation of Capillarized Sinusoids and Trabecular Structure in Human Hepatocellular Carcinoma Tissues.

PubMed

Jian, Jianbo; Zhang, Wenxue; Yang, Hao; Zhao, Xinyan; Xuan, Ruijiao; Li, Dongyue; Hu, Chunhong

2017-01-01

Capillarization of sinusoids and change of trabecular thickness are the main histologic features in hepatocellular carcinoma (HCC). Of particular interest are the three-dimensional (3D) visualization and quantitative evaluation of such alterations in the HCC progression. X-ray phase-contrast computed tomography (PCCT) is an emerging imaging method that provides excellent image contrast for soft tissues. This study aimed to explore the potential of in-line PCCT in microstructure imaging of capillarized sinusoids and trabecular structure in human HCC tissues and to quantitatively evaluate the alterations of those fine structures during the development of HCC. This project was designed as an ex vivo experimental study. The study was approved by the institutional review board, and informed consent was obtained from the patients. Eight human resected HCC tissue samples were imaged using in-line PCCT. After histologic processing, PCCT images and histopathologic data were matched. Fine structures in HCC tissues were revealed. Quantitative analyses of capillarized sinusoids (ie, percentage of sinusoidal area [PSA], sinusoidal volume) and trabecular structure (ie, trabecular thickness, surface-area-to-volume ratio [SA/V]) in low-grade (well or moderately differentiated) and high-grade (poorly differentiated) HCC groups were performed. Using PCCT, the alterations of capillarized sinusoids and trabecular structure were clearly observed in 3D geometry, which was confirmed by the corresponding histologic sections. The 3D qualitative analyses of sinusoids in the high-grade HCC group were significantly different (P < 0.05) in PSA (7.8 ± 2.5%) and sinusoidal volume (2.9 ± 0.6 × 10 7  µm 3 ) from those in the low-grade HCC group (PSA, 12.9 ± 2.2%; sinusoidal volume, 2.4 ± 0.3 × 10 7  µm 3 ). Moreover, the 3D quantitative evaluation of the trabecular structure in the high-grade HCC group showed a significant change (P < 0.05) in the

Correlates of Trabecular and Cortical Volumetric Bone Mineral Density of the Radius and Tibia in Older Men: The Osteoporotic Fractures in Men Study

PubMed Central

Barbour, Kamil E; Zmuda, Joseph M; Strotmeyer, Elsa S; Horwitz, Mara J; Boudreau, Robert; Evans, Rhobert W; Ensrud, Kristine E; Petit, Moira A; Gordon, Christopher L; Cauley, Jane A

2010-01-01

Quantitative computed tomography (QCT) can estimate volumetric bone mineral density (vBMD) and distinguish trabecular from cortical bone. Few comprehensive studies have examined correlates of vBMD in older men. This study evaluated the impact of demographic, anthropometric, lifestyle, and medical factors on vBMD in 1172 men aged 69 to 97 years and enrolled in the Osteoporotic Fractures in Men Study (MrOS). Peripheral quantitative computed tomography (pQCT) was used to measure vBMD of the radius and tibia. The multivariable linear regression models explained up to 10% of the variance in trabecular vBMD and up to 9% of the variance in cortical vBMD. Age was not correlated with radial trabecular vBMD. Correlates associated with both cortical and trabecular vBMD were age (−), caffeine intake (−), total calcium intake (+), nontrauma fracture (−), and hypertension (+). Higher body weight was related to greater trabecular vBMD and lower cortical vBMD. Height (−), education (+), diabetes with thiazolidinedione (TZD) use (+), rheumatoid arthritis (+), using arms to stand from a chair (−), and antiandrogen use (−) were associated only with trabecular vBMD. Factors associated only with cortical vBMD included clinic site (−), androgen use (+), grip strength (+), past smoker (−), and time to complete five chair stands (−). Certain correlates of trabecular and cortical vBMD differed among older men. An ascertainment of potential risk factors associated with trabecular and cortical vBMD may lead to better understanding and preventive efforts for osteoporosis in men. © 2010 American Society for Bone and Mineral Research. PMID:20200975

Aqueous Angiography–Mediated Guidance of Trabecular Bypass Improves Angiographic Outflow in Human Enucleated Eyes

PubMed Central

Huang, Alex S.; Saraswathy, Sindhu; Dastiridou, Anna; Begian, Alan; Mohindroo, Chirayu; Tan, James C. H.; Francis, Brian A.; Hinton, David R.; Weinreb, Robert N.

2016-01-01

Purpose To assess the ability of trabecular micro-bypass stents to improve aqueous humor outflow (AHO) in regions initially devoid of AHO as assessed by aqueous angiography. Methods Enucleated human eyes (14 total from 7 males and 3 females [ages 52–84]) were obtained from an eye bank within 48 hours of death. Eyes were oriented by inferior oblique insertion, and aqueous angiography was performed with indocyanine green (ICG; 0.4%) or fluorescein (2.5%) at 10 mm Hg. With an angiographer, infrared and fluorescent images were acquired. Concurrent anterior segment optical coherence tomography (OCT) was performed, and fixable fluorescent dextrans were introduced into the eye for histologic analysis of angiographically positive and negative areas. Experimentally, some eyes (n = 11) first received ICG aqueous angiography to determine angiographic patterns. These eyes then underwent trabecular micro-bypass sham or stent placement in regions initially devoid of angiographic signal. This was followed by fluorescein aqueous angiography to query the effects. Results Aqueous angiography in human eyes yielded high-quality images with segmental patterns. Distally, angiographically positive but not negative areas demonstrated intrascleral lumens on OCT images. Aqueous angiography with fluorescent dextrans led to their trapping in AHO pathways. Trabecular bypass but not sham in regions initially devoid of ICG aqueous angiography led to increased aqueous angiography as assessed by fluorescein (P = 0.043). Conclusions Using sequential aqueous angiography in an enucleated human eye model system, regions initially without angiographic flow or signal could be recruited for AHO using a trabecular bypass stent. PMID:27588614

Bone apatite composition of necrotic trabecular bone in the femoral head of immature piglets.

PubMed

Aruwajoye, Olumide O; Kim, Harry K W; Aswath, Pranesh B

2015-04-01

Ischemic osteonecrosis of the femoral head (IOFH) can lead to excessive resorption of the trabecular bone and collapse of the femoral head as a structure. A well-known mineral component to trabecular bone is hydroxyapatite, which can be present in many forms due to ionic substitution, thus altering chemical composition. Unfortunately, very little is known about the chemical changes to bone apatite following IOFH. We hypothesized that the apatite composition changes in necrotic bone possibly contribute to increased osteoclast resorption and structural collapse of the femoral head. The purpose of this study was to assess the macroscopic and local phosphate composition of actively resorbed necrotic trabecular bone to isolate differences between areas of increased osteoclast resorption and normal bone formation. A piglet model of IOFH was used. Scanning electron microscopy (SEM), histology, X-ray absorbance near edge structure (XANES), and Raman spectroscopy were performed on femoral heads to characterize normal and necrotic trabecular bone. Backscattered SEM, micro-computed tomography and histology showed deformity and active resorption of necrotic bone compared to normal. XANES and Raman spectroscopy obtained from actively resorbed necrotic bone and normal bone showed increased carbonate-to-phosphate content in the necrotic bone. The changes in the apatite composition due to carbonate substitution may play a role in the increased resorption of necrotic bone due to its increase in solubility. Indeed, a better understanding of the apatite composition of necrotic bone could shed light on osteoclast activity and potentially improve therapeutic treatments that target excessive resorption of bone.

Commercially available trabecular metal ankle interpositional spacer for tibiotalocalcaneal arthrodesis secondary to severe bone loss of the ankle.

PubMed

Horisberger, Monika; Paul, Jochen; Wiewiorski, Martin; Henninger, Heath B; Khalifa, Muhammad S; Barg, Alexej; Valderrabano, Victor

2014-01-01

Retrograde tibiotalocalcaneal nailing arthrodesis has proved to be a viable salvage procedure; however, extended bone loss around the ankle has been associated with high rates of nonunion and considerable shortening of the hindfoot. We present the surgical technique and the first 2 cases in which a trabecular metal™ interpositional spacer, specifically designed for tibiotalocalcaneal nailing arthrodesis, was used. The spacer can be implanted using either an anterior or a lateral approach. An integrated hole in the spacer allows a retrograde nail to be inserted, which provides excellent primary stability of the construct. Trabecular metal™ is a well-established and well-described material used to supplement deficient bone stock in surgery of the spine, hip, and knee. It has shown excellent incorporation and reduces the need for auto- and allografts. The trabecular metal™ interpositional ankle spacer is the first trabecular metal spacer designed specifically for ankle surgery. Its shape and variable size will make it a valuable tool for reconstructing bone loss in tibiotalocalcaneal nailing arthrodesis. Copyright © 2014 American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.

Functional delivery of synthetic naked siRNA to the human trabecular meshwork in perfused organ cultures.

PubMed

Comes, Nuria; Borrás, Teresa

2007-08-01

To investigate whether naked short-interfering RNA (siRNA) molecules could be directly delivered to perfused intact human trabecular meshwork (TM) tissue, whether this siRNA could silence a trabecular meshwork preferred gene, and whether it could counteract the downstream effect of a deleterious agent (dexamethasone, DEX) by silencing its receptor. Anterior segments from post-mortem normal human donors were perfused at 3.4+/-0.3 microl/min-constant flow or 15 mmHg-constant pressure to stable baseline (outflow facility, C=0.22+/-0.19 microl/min/mmHg; n=14). Commercial siRNAs were diluted in DMEM (Dulbecco's Modified Eagle's Medium) perfusion medium and used without coupling to transfection reagents ("naked"). Perfusion of Cy3-labeled siRNA was performed at 100 nM for 48 h followed by 24 h with DMEM medium (two pairs). Perfusions of Matrix GLA protein (MGP) siRNA (100 nM; right eye [Oculus Dexter]; OD) and scramble-siRNA (control; left eye [Oculus Sinster]; OS) were performed for 48 h (two pairs). Perfusions of glucocorticoid receptor (GR)-siRNA (OD) and scramble-control (OS) were performed for 48 h and continued by adding 100 nM DEX to the perfusion media for an additional 24 h (two pairs). Frozen sections of labeled anterior segments were analyzed by confocal fluorescence microscopy. Differential expression of GR, MGP, myocilin (MYOC), cornea-derived transcript 6 (CDT6), and 18S genes was determined by reverse-transcriptase TaqMan polymerase chain reacion (RT-TaqMan PCR) on RNA extracted from dissected trabecular meshwork. Primary human trabecular meshwork cells were generated from single individuals and transfected using the nucleofector electroporator with program T-23. Levels of secreted MYOC in the effluents were analyzed by western blot. Histological evaluation of anterior segments perfused with Cy3 labeled siRNA followed by unlabeled medium showed intense fluorescence in the trabecular meshwork region. MGP gene expression was silenced in the trabecular

High resolution magnetic resonance imaging of the calcaneus: age-related changes in trabecular structure and comparison with dual X-ray absorptiometry measurements

NASA Technical Reports Server (NTRS)

Ouyang, X.; Selby, K.; Lang, P.; Engelke, K.; Klifa, C.; Fan, B.; Zucconi, F.; Hottya, G.; Chen, M.; Majumdar, S.;

Adaptations in the Microarchitecture and Load Distribution of Maternal Cortical and Trabecular Bone in Response to Multiple Reproductive Cycles in Rats

PubMed Central

de Bakker, Chantal M. J.; Altman-Singles, Allison R.; Li, Yihan; Tseng, Wei-Ju; Li, Connie; Liu, X. Sherry

2017-01-01

Pregnancy, lactation, and weaning result in dramatic changes in maternal calcium metabolism. In particular, the increased calcium demand during lactation causes a substantial degree of maternal bone loss. This reproductive bone loss has been suggested to be largely reversible, as multiple clinical studies have found that parity and lactation history have no adverse effect on post-menopausal fracture risk. However, the precise effects of pregnancy, lactation, and post-weaning recovery on maternal bone structure are not well understood. Our study aimed to address this question by longitudinally tracking changes in trabecular and cortical bone microarchitecture at the proximal tibia in rats throughout three cycles of pregnancy, lactation, and post-weaning using in vivo μCT. We found that the trabecular thickness underwent a reversible deterioration during pregnancy and lactation, which was fully recovered after weaning, while other parameters of trabecular microarchitecture (including trabecular number, spacing, connectivity density, and structure model index) underwent a more permanent deterioration which recovered minimally. Thus, pregnancy and lactation resulted in both transient and long-lasting alterations in trabecular microstructure. In the meantime, multiple reproductive cycles appeared to improve the robustness of cortical bone (resulting in an elevated cortical area and polar moment of inertia), as well as increase the proportion of the total load carried by the cortical bone at the proximal tibia. Taken together, changes in the cortical and trabecular compartments suggest that while rat tibial trabecular bone appears to be highly involved in maintaining calcium homeostasis during female reproduction, cortical bone adapts to increase its load-bearing capacity, allowing the overall mechanical function of the tibia to be maintained. PMID:28109138

Glycemic control protects against trabecular bone microarchitectural damage in a juvenile male rat model of streptozotocin-induced diabetes.

PubMed

de Oliveira, Guilherme José Pimentel Lopes; Basso, Túlio Luiz Durigan; Fontanari, Lucas Amaral; Faloni, Ana Paula de Souza; Marcantonio, Élcio; Orrico, Silvana Regina Perez

2017-08-01

To determine which features of the bone microarchitecture are affected by established diabetes mellitus (DM) and the effectiveness of glycemic control in the protection of bone tissue. Sixty juvenile Wistar male rats were divided into three groups of 20 animals: a control group (C) that included healthy animals, a diabetic group (D) that included animals with induced diabetes, and a controlled diabetic group (CD) that included animals with induced diabetes that were treated with insulin. The animals were euthanized at the periods of 6 and 8 weeks after the induction of diabetes (10 animals per group/period). Vertebral L4 specimens were submitted to μCT analysis to assess the following parameters of the bone microarchitecture: bone volume fraction (BV/TV), trabecular thickness (Tb.Th), trabecular number (Tb.N), and trabecular spacing (Tb.Sp). The D group exhibited lower values of BV/TV (%) and numbers of trabeculae compared with the C group at 6 and 8 weeks and compared with the CD group at 8 weeks. The CD group exhibited higher trabecular thickness values compared with the D group at 8 weeks. There were no differences between the groups regarding the spaces between the trabeculae. Induced diabetes affected the microarchitecture of the trabecular bone of the vertebrae by reducing the values of the majority of the parameters in relation to those of the control group. Glycemic control with insulin appears to protect bones from the effects of the hyperglycemia.

Time-lapsed investigation of three-dimensional failure and damage accumulation in trabecular bone using synchrotron light.

PubMed

Thurner, P J; Wyss, P; Voide, R; Stauber, M; Stampanoni, M; Sennhauser, U; Müller, R

2006-08-01

Synchrotron radiation micro-computed tomography (SRmicroCT) is a very useful technique when it comes to three-dimensional (3D) imaging of complex internal and external geometries. Being a fully non-destructive technique, SRmicroCT can be combined with other experiments in situ for functional imaging. We are especially interested in the combination of SRmicroCT with mechanical testing in order to gain new insights in the failure mechanism of trabecular bone. This interest is motivated by the immense costs in health care due to patients suffering from osteoporosis, a systemic skeletal disease resulting in decreased bone stability and increased fracture risk. To better investigate the different failure mechanisms on the microlevel, we have developed a novel in situ mechanical compression device, capable of exerting both static and dynamic displacements on experimental samples. The device was calibrated for mechanical testing using solid aluminum and bovine trabecular bone samples. To study different failure mechanisms in trabecular bone, we compared a fatigued and a non-fatigued bovine bone sample with respect to failure initiation and propagation. The fatigued sample failed in a burst-like fashion in contrast to the non-fatigued sample, which exhibited a distinct localized failure band. Moreover, microscopic cracks - microcracks and microfractures - were uncovered in a 3D fashion illustrating the failure process in great detail. The majority of these cracks were connected to a bone surface. The data also showed that the classification of microcracks and -fractures from 2D section can sometimes be ambiguous, which is also true for the distinction of diffuse and distinct microdamage. Detailed investigation of the failure mechanism in these samples illustrated that trabecular bone often fails in delamination, providing a mechanism for energy dissipation while conserving trabecular bone architecture. In the future, this will allow an even better understanding of bone

Sex-specific patterns in cortical and trabecular bone microstructure in the Kirsten Skeletal Collection, South Africa.

PubMed

Beresheim, Amy C; Pfeiffer, Susan K; Grynpas, Marc D; Alblas, Amanda

2018-02-07

The purpose of this study was to provide bone histomorphometric reference data for South Africans of the Western Cape who likely dealt with health issues under the apartheid regime. The 206 adult individuals ( n female = 75, n male = 131, mean = 47.9 ± 15.8 years) from the Kirsten Skeletal Collection, U. Stellenbosch, lived in the Cape Town metropole from the late 1960s to the mid-1990s. To study age-related changes in cortical and trabecular bone microstructure, photomontages of mid-thoracic rib cross-sections were quantitatively examined. Variables include relative cortical area (Rt.Ct.Ar), osteon population density (OPD), osteon area (On.Ar), bone volume fraction (BV/TV), trabecular number (Tb.N), trabecular thickness (Tb.Th), and trabecular spacing (Tb.Sp). All cortical variables demonstrated significant relationships with age in both sexes, with women showing stronger overall age associations. Peak bone mass was compromised in some men, possibly reflecting poor nutritional quality and/or substance abuse issues throughout adolescence and early adulthood. In women, greater predicted decrements in On.Ar and Rt.Ct.Ar suggest a structural disadvantage with age, consistent with postmenopausal bone loss. Age-related patterns in trabecular bone microarchitecture are variable and difficult to explain. Except for Tb.Th, there are no statistically significant relationships with age in women. Men demonstrate significant negative correlations between BV/TV, Tb.N, and age, and a significant positive correlation between Tb.Sp and age. This research highlights sex-specific differences in patterns of age-related bone loss, and provides context for discussion of contemporary South African bone health. While the study sample demonstrates indicators of poor bone quality, osteoporosis research continues to be under-prioritized in South Africa. © 2018 Wiley Periodicals, Inc.

An integral biochemical analysis of the main constituents of articular cartilage, subchondral and trabecular bone.

PubMed

van der Harst, Mark R; Brama, Pieter A J; van de Lest, Chris H A; Kiers, Geesje H; DeGroot, Jeroen; van Weeren, P René

2004-09-01

In articular joints, the forces generated by locomotion are absorbed by the whole of cartilage, subchondral bone and underlying trabecular bone. The objective of this study is to test the hypothesis that regional differences in joint loading are related to clear and interrelated differences in the composition of the extracellular matrix (ECM) of all three weight-bearing constituents. Cartilage, subchondral- and trabecular bone samples from two differently loaded sites (site 1, dorsal joint margin; site 2, central area) of the proximal articular surface of 30 macroscopically normal equine first phalanxes were collected. Collagen content, cross-linking (pentosidine, hydroxylysylpyridinoline (HP), lysylpyridinoline (LP)) hydroxylation, and denaturation, as well as glycosaminoglycan (GAG) and DNA content were measured in all three tissues. In addition, bone mineral density (BMD), the percentage of ash and the mineral composition (calcium, magnesium and phosphorus) were determined in the bony samples. For pentosidine cross-links there was an expected correlation with age. Denatured collagen content was significantly higher in cartilage at site 1 than at site 2 and was higher in trabecular bone compared to subchondral bone, with no site differences. There were significant site differences in hydroxylysine (Hyl) concentration and HP cross-links in cartilage that were paralleled in one or both of the bony layers. In subchondral bone there was a positive correlation between total (HP+LP) cross-links and Ca content. For Ca and other minerals there were corresponding site differences in both bony layers. It is concluded that there are distinct differences in distribution of the major biochemical components over both sites in all three layers. These differences show similar patterns in cartilage, subchondral bone and trabecular bone, stressing the functional unity of these tissues. Overall, differences could be interpreted as adaptations to a considerably higher cumulative

The correlation between the SOS in trabecular bone and stiffness and density studied by finite-element analysis.

PubMed

Goossens, Liesbet; Vanderoost, Jef; Jaecques, Siegfried; Boonen, Steven; D'hooge, Jan; Lauriks, Walter; Van der Perre, Georges

2008-01-01

For the clinical assessment of osteoporosis (i.e., a degenerative bone disease associated with increased fracture risk), ultrasound has been proposed as an alternative or supplement to the dual-energy X-ray absorptiometry (DEXA) technique. However, the interaction of ultrasound waves with (trabecular) bone remains relatively poorly understood. The present study aimed to improve this understanding by simulating ultrasound wave propagation in 15 trabecular bone samples from the human lumbar spine, using microcomputed tomography-based finite-element modeling. The model included only the solid bone, without the bone marrow. Two structural parameters were calculated: the bone volume fraction (BV/TV) and the structural (apparent) elastic modulus (E(s)), and the ultrasound propagation parameter speed of sound (SOS). Relations between BV/TV and E(s) were similar to published experimental relations. At 1 MHz, correlations between SOS and the structural parameters BV/TV and Es were rather weak, but the results can be explained from the specific features of the trabecular structure and the intrinsic material elastic modulus E(i). In particular, the systematic differences between the three main directions provide information on the trabecular structure. In addition, at 1 MHz the correlation found between the simulated SOS values and those calculated from the simple bar equation was poor when the three directions are considered separately. Hence, under these conditions, the homogenization approach-including the bar equation-is not valid. However, at lower frequencies (50-300 kHz) this correlation significantly improved. It is concluded that detailed analysis of ultrasound wave propagation through the solid structure in various directions and with various frequencies, can yield much information on the structural and mechanical properties of trabecular bone.

Modeling and analysis of multiple scattering of acoustic waves in complex media: application to the trabecular bone.

PubMed

Wojcik, J; Litniewski, J; Nowicki, A

2011-10-01

The integral equations that describe scattering in the media with step-rise changing parameters have been numerically solved for the trabecular bone model. The model consists of several hundred discrete randomly distributed elements. The spectral distribution of scattering coefficients in subsequent orders of scattering has been presented. Calculations were carried on for the ultrasonic frequency ranging from 0.5 to 3 MHz. Evaluation of the contribution of the first, second, and higher scattering orders to total scattering of the ultrasounds in trabecular bone was done. Contrary to the approaches that use the μCT images of trabecular structure to modeling of the ultrasonic wave propagation condition, the 3D numerical model consisting of cylindrical elements mimicking the spatial matrix of trabeculae, was applied. The scattering, due to interconnections between thick trabeculae, usually neglected in trabecular bone models, has been included in calculations when the structure backscatter was evaluated. Influence of the absorption in subsequent orders of scattering is also addressed. Results show that up to 1.5 MHz, the influence of higher scattering orders on the total scattered field characteristic can be neglected while for the higher frequencies, the relatively high amplitude interference peaks in higher scattering orders clearly occur. © 2011 Acoustical Society of America

[Influence of trabecular microstructure modeling on finite element analysis of dental implant].

PubMed

Shen, M J; Wang, G G; Zhu, X H; Ding, X

2016-09-01

To analyze the influence of trabecular microstructure modeling on the biomechanical distribution of implant-bone interface with a three-dimensional finite element mandible model of trabecular structure. Dental implants were embeded in the mandibles of a beagle dog. After three months of the implant installation, the mandibles with dental implants were harvested and scaned by micro-CT and cone-beam CT. Two three-dimensional finite element mandible models, trabecular microstructure(precise model) and macrostructure(simplified model), were built. The values of stress and strain of implant-bone interface were calculated using the software of Ansys 14.0. Compared with the simplified model, the precise models' average values of the implant bone interface stress increased obviously and its maximum values did not change greatly. The maximum values of quivalent stress of the precise models were 80% and 110% of the simplified model and the average values were 170% and 290% of simplified model. The maximum and average values of equivalent strain of precise models were obviously decreased, and the maximum values of the equivalent effect strain were 17% and 26% of simplified model and the average ones were 21% and 16% of simplified model respectively. Stress and strain concentrations at implant-bone interface were obvious in the simplified model. However, the distributions of stress and strain were uniform in the precise model. The precise model has significant effect on the distribution of stress and strain at implant-bone interface.

The pattern of trabecular bone microarchitecture in the distal femur of typically developing children and its effect on processing of magnetic resonance images.

PubMed

Modlesky, Christopher M; Whitney, Daniel G; Carter, Patrick T; Allerton, Brianne M; Kirby, Joshua T; Miller, Freeman

2014-03-01

Magnetic resonance imaging (MRI) is used to assess trabecular bone microarchitecture in humans; however, image processing can be labor intensive and time consuming. One aim of this study was to determine the pattern of trabecular bone microarchitecture in the distal femur of typically developing children. A second aim was to determine the proportion and location of magnetic resonance images that need to be processed to yield representative estimates of trabecular bone microarchitecture. Twenty-six high resolution magnetic resonance images were collected immediately above the growth plate in the distal femur of 6-12year-old typically developing children (n=40). Measures of trabecular bone microarchitecture [i.e., apparent trabecular bone volume to total volume (appBV/TV), trabecular number (appTb.N), trabecular thickness (appTb.Th) and trabecular separation (appTb.Sp)] in the lateral aspect of the distal femur were determined using the twenty most central images (20IM). The average values for appBV/TV, appTb.N, appTb.Th and appTb.Sp from 20IM were compared to the average values from 10 images (10IM), 5 images (5IM) and 3 images (3IM) equally dispersed throughout the total image set and one image (1IM) from the center of the total image set using linear regression analysis. The resulting mathematical models were cross-validated using the leave-one-out technique. Distance from the growth plate was strongly and inversely related to appBV/TV (r(2)=0.68, p<0.001) and appTb.N (r(2)=0.92, p<0.001) and was strongly and positively related to appTb.Sp (r(2)=0.86, p<0.001). The relationship between distance from the growth plate and appTb.Th was not linear (r(2)=0.06, p=0.28), but instead it was quadratic and statistically significant (r(2)=0.54, p<0.001). Trabecular bone microarchitecture estimates from 10IM, 5IM, 3IM and 1IM were not different from estimates from 20IM (p>0.05). However, there was a progressive decrease in the strength of the relationships as a smaller

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

PubMed

Sapthagirivasan, V; Anburajan, M; Janarthanam, S

2015-08-01

The early detection of osteoporosis risk enhances the lifespan and quality of life of an individual. A reasonable in-vivo assessment of trabecular bone strength at the proximal femur helps to evaluate the fracture risk and henceforth, to understand the associated structural dynamics on occurrence of osteoporosis. The main aim of our study was to develop a framework to automatically determine the trabecular bone strength from clinical femur CT images and thereby to estimate its correlation with BMD. All the 50 studied south Indian female subjects aged 30 to 80 years underwent CT and DXA measurements at right femur region. Initially, the original CT slices were intensified and active contour model was utilised for the extraction of the neck region. After processing through a novel process called trabecular enrichment approach (TEA), the three dimensional (3D) trabecular features were extracted. The extracted 3D trabecular features, such as volume fraction (VF), solidity of delta points (SDP) and boundness, demonstrated a significant correlation with femoral neck bone mineral density (r = 0.551, r = 0.432, r = 0.552 respectively) at p < 0.001. The higher area under the curve values of the extracted features (VF: 85.3 %; 95CI: 68.2-100 %, SDP: 82.1 %; 95CI: 65.1-98.9 % and boundness: 90.4 %; 95CI: 78.7-100 %) were observed. The findings suggest that the proposed framework with TEA method would be useful for spotting women vulnerable to osteoporotic risk.

[Analysis of correlation between trabecular microstructure and clinical imaging parameters in fracture region of osteoporotic hip].

PubMed

Peng, Jing; Zhou, Yong; Min, Li; Zhang, Wenli; Luo, Yi; Zhang, Xuelei; Zou, Chang; Shi, Rui; Tu, Chongqi

2014-05-01

To analyze the correlation between the trabecular microstructure and the clinical imaging parameters in the fracture region of osteoporotic hip so as to provide a simple method to evaluate the trabecular microstructure by a non-invasive way. Between June 2012 and January 2013, 16 elderly patients with femoral neck fracture underwent hip arthroplasty were selected as the trial group; 5 young patients with pelvic fracture were selected as the control group. The hip CT examination was done, and cancellous bone volume/marrow cavity volume (CV/MV) was analyzed with Mimics 10.01 software in the control group. The CT scan and bone mineral density (BMD) measurement were performed on normal hips of the trial group, and cuboid specimens were gained from the femoral necks at the place of the tensional trabeculae to evaluate the trabecular microstructure parameters by Micro-CT, including bone volume fraction (BV/TV), trabecular number (Tb.N), trabecular spacing (Tb.Sp), trabecular thickness (Tb.Th), connect density (Conn.D), and structure model index (SMI). The correlation between imaging parameters and microstructure parameters was analyzed. In the trial group, the BMD value was 0.491-0.698 g/cm2 (mean, 0.601 g/cm2); according to World Health Organization (WHO) standard, 10 cases were diagnosed as having osteoporosis, and 6 cases as having osteopenia. The CV/MV of the trial group (0.670 1 +/- 0.102 0) was significantly lower than that of the control group (0.885 0 +/- 0.089 1) (t = -4.567, P = 0.000). In the trial group, CV/MV had correlation with BV/TV, Tb.Th, and SMI (P < 0.05); however, CV/MV had no correlation with Tb.N, Tb.Sp, or Conn.D (P > 0.05). BV/TV had correlation with Tb.Th, Tb.N, Tb.Sp, and SMI (P < 0.05), but it had no correlation with Conn.D (P=0.075). There was no correlation between BMD and microstructure parameters (P > 0.05). CV/MV obviously decreases in the osteoporotic hip, and there is a correlation between CV/MV and the microstructure parameters of BV

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

PubMed

von Meyer, Georg Hermann

2011-11-01

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

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

PubMed

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

2016-06-01

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

Generation of an Atlas of the Proximal Femur and Its Application to Trabecular Bone Analysis

PubMed Central

Carballido-Gamio, Julio; Folkesson, Jenny; Karampinos, Dimitrios C.; Baum, Thomas; Link, Thomas M.; Majumdar, Sharmila; Krug, Roland

2013-01-01

Automatic placement of anatomically corresponding volumes of interest and comparison of parameters against a standard of reference are essential components in studies of trabecular bone. Only recently, in vivo MR images of the proximal femur, an important fracture site, could be acquired with high-spatial resolution. The purpose of this MRI trabecular bone study was two-fold: (1) to generate an atlas of the proximal femur to automatically place anatomically corresponding volumes of interest in a population study and (2) to demonstrate how mean models of geodesic topological analysis parameters can be generated to be used as potential standard of reference. Ten females were used to generate the atlas and geodesic topological analysis models, and 10 females were used to demonstrate the atlas-based trabecular bone analysis. All alignments were based on three-dimensional (3D) multiresolution affine transformations followed by 3D multiresolution free-form deformations. Mean distances less than 1 mm between aligned femora, and sharp edges in the atlas and in fused gray-level images of registered femora indicated that the anatomical variability was well accommodated and explained by the free-form deformations. PMID:21432904

Bone mineral density changes of lumbar spine and femur in osteoporotic patient treated with bisphosphonates and beta-hydroxy-beta-methylbutyrate (HMB): Case report.

PubMed

Tatara, Marcin R; Krupski, Witold; Majer-Dziedzic, Barbara

2017-10-01

Currently available approaches to osteoporosis treatment include application of antiresorptive and anabolic agents influencing bone tissue metabolism. The aim of the study was to present bone mineral density (BMD) changes of lumbar spine in osteoporotic patient treated with bisphosphonates such as ibandronic acid and pamidronic acid, and beta-hydroxy-beta-methylbutyrate (HMB). BMD and volumetric BMD (vBMD) of lumbar spine were measured during the 6 year observation period with the use of dual-energy X-ray absorptiometry (DEXA) and quantitative computed tomography (QCT). The described case report of osteoporotic patient with family history of severe osteoporosis has shown site-dependent response of bone tissue to antiosteoporotic treatment with bisphosphonates. Twenty-five-month treatment with ibandronic acid improved proximal femur BMD with relatively poor effects on lumbar spine BMD. Over 15-month therapy with pamidronic acid was effective to improve lumbar spine BMD, while in the proximal femur the treatment was not effective. A total of 61-week long oral administration with calcium salt of HMB improved vBMD of lumbar spine in the trabecular and cortical bone compartments when monitored by QCT. Positive effects of nearly 2.5 year HMB treatment on BMD of lumbar spine and femur in the patient were also confirmed using DEXA method. The results obtained indicate that HMB may be applied for the effective treatment of osteoporosis in humans. Further studies on wider human population are recommended to evaluate mechanisms influencing bone tissue metabolism by HMB.

Rapamycin attenuates pathological hypertrophy caused by an absence of trabecular formation.

PubMed

Fleming, Nicole D; Samsa, Leigh A; Hassel, David; Qian, Li; Liu, Jiandong

2018-06-05

Cardiac trabeculae are mesh-like muscular structures within ventricular walls. Subtle perturbations in trabeculation are associated with many congenital heart diseases (CHDs), and complete failure to form trabeculae leads to embryonic lethality. Despite the severe consequence of an absence of trabecular formation, the exact function of trabeculae remains unclear. Since ErbB2 signaling plays a direct and essential role in trabecular initiation, in this study, we utilized the erbb2 zebrafish mutant as a model to address the function of trabeculae in the heart. Intriguingly, we found that the trabeculae-deficient erbb2 mutant develops a hypertrophic-like (HL) phenotype that can be suppressed by inhibition of Target of Rapamycin (TOR) signaling in a similar fashion to adult mammalian hearts subjected to mechanical overload. Further, cell transplantation experiments demonstrated that erbb2 mutant cells in an otherwise wildtype heart did not undergo hypertrophy, indicating that erbb2 mutant HL phenotypes are due to a loss of trabeculae. Together, we propose that trabeculae serve to enhance contractility and that defects in this process lead to wall-stress induced hypertrophic remodeling.

Osteoblast-Specific Overexpression of Human WNT16 Increases Both Cortical and Trabecular Bone Mass and Structure in Mice

PubMed Central

Alkhouli, Mohammed; Gerard-O'Riley, Rita L.; Wright, Weston B.; Acton, Dena; Gray, Amie K.; Patel, Bhavmik; Reilly, Austin M.; Lim, Kyung-Eun; Robling, Alexander G.; Econs, Michael J.

2016-01-01

Previous genome-wide association studies have identified common variants in genes associated with bone mineral density (BMD) and risk of fracture. Recently, we identified single nucleotide polymorphisms (SNPs) in Wingless-type mouse mammary tumor virus integration site (WNT)16 that were associated with peak BMD in premenopausal women. To further identify the role of Wnt16 in bone mass regulation, we created transgenic (TG) mice overexpressing human WNT16 in osteoblasts. We compared bone phenotypes, serum biochemistry, gene expression, and dynamic bone histomorphometry between TG and wild-type (WT) mice. Compared with WT mice, WNT16-TG mice exhibited significantly higher whole-body areal BMD and bone mineral content (BMC) at 6 and 12 weeks of age in both male and female. Microcomputer tomography analysis of trabecular bone at distal femur revealed 3-fold (male) and 14-fold (female) higher bone volume/tissue volume (BV/TV), and significantly higher trabecular number and trabecular thickness but lower trabecular separation in TG mice compared with WT littermates in both sexes. The cortical bone at femur midshaft also displayed significantly greater bone area/total area and cortical thickness in the TG mice in both sexes. Serum biochemistry analysis showed that male TG mice had higher serum alkaline phosphatase, osteocalcin, osteoprotegerin (OPG), OPG to receptor activator of NF-kB ligand (tumor necrosis family ligand superfamily, number 11; RANKL) ratio as compared with WT mice. Also, lower carboxy-terminal collagen cross-link (CTX) to tartrate-resistant acid phosphatase 5, isoform b (TRAPc5b) ratio was observed in TG mice compared with WT littermates in both male and female. Histomorphometry data demonstrated that both male and female TG mice had significantly higher cortical and trabecular mineralizing surface/bone surface and bone formation rate compared with sex-matched WT mice. Gene expression analysis demonstrated higher expression of Alp, OC, Opg, and Opg to

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

NASA Astrophysics Data System (ADS)

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

2016-03-01

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

A computer-aided system for automatic extraction of femur neck trabecular bone architecture using isotropic volume construction from clinical hip computed tomography images.

PubMed

Vivekanandhan, Sapthagirivasan; Subramaniam, Janarthanam; Mariamichael, Anburajan

2016-10-01

Hip fractures due to osteoporosis are increasing progressively across the globe. It is also difficult for those fractured patients to undergo dual-energy X-ray absorptiometry scans due to its complicated protocol and its associated cost. The utilisation of computed tomography for the fracture treatment has become common in the clinical practice. It would be helpful for orthopaedic clinicians, if they could get some additional information related to bone strength for better treatment planning. The aim of our study was to develop an automated system to segment the femoral neck region, extract the cortical and trabecular bone parameters, and assess the bone strength using an isotropic volume construction from clinical computed tomography images. The right hip computed tomography and right femur dual-energy X-ray absorptiometry measurements were taken from 50 south-Indian females aged 30-80 years. Each computed tomography image volume was re-constructed to form isotropic volumes. An automated system by incorporating active contour models was used to segment the neck region. A minimum distance boundary method was applied to isolate the cortical and trabecular bone components. The trabecular bone was enhanced and segmented using trabecular enrichment approach. The cortical and trabecular bone features were extracted and statistically compared with dual-energy X-ray absorptiometry measured femur neck bone mineral density. The extracted bone measures demonstrated a significant correlation with neck bone mineral density (r > 0.7, p < 0.001). The inclusion of cortical measures, along with the trabecular measures extracted after isotropic volume construction and trabecular enrichment approach procedures, resulted in better estimation of bone strength. The findings suggest that the proposed system using the clinical computed tomography images scanned with low dose could eventually be helpful in osteoporosis diagnosis and its treatment planning. © IMechE 2016.

An investigation of the inelastic behaviour of trabecular bone during the press-fit implantation of a tibial component in total knee arthroplasty.

PubMed

Kelly, N; Cawley, D T; Shannon, F J; McGarry, J P

2013-11-01

The stress distribution and plastic deformation of peri-prosthetic trabecular bone during press-fit tibial component implantation in total knee arthroplasty is investigated using experimental and finite element techniques. It is revealed that the computed stress distribution, implantation force and plastic deformation in the trabecular bone is highly dependent on the plasticity formulation implemented. By incorporating pressure dependent yielding using a crushable foam plasticity formulation to simulate the trabecular bone during implantation, highly localised stress concentrations and plastic deformation are computed at the bone-implant interface. If the pressure dependent yield is neglected using a traditional von Mises plasticity formulation, a significantly different stress distribution and implantation force is computed in the peri-prosthetic trabecular bone. The results of the study highlight the importance of: (i) simulating the insertion process of press-fit stem implantation; (ii) implementing a pressure dependent plasticity formulation, such as the crushable foam plasticity formulation, for the trabecular bone; (iii) incorporating friction at the implant-bone interface during stem insertion. Simulation of the press-fit implantation process with an appropriate pressure dependent plasticity formulation should be implemented in the design and assessment of arthroplasty prostheses. Copyright © 2013 IPEM. Published by Elsevier Ltd. All rights reserved.

Characterization of synthetic foam structures used to manufacture artificial vertebral trabecular bone.

PubMed

Fürst, David; Senck, Sascha; Hollensteiner, Marianne; Esterer, Benjamin; Augat, Peter; Eckstein, Felix; Schrempf, Andreas

2017-07-01

Artificial materials reflecting the mechanical properties of human bone are essential for valid and reliable implant testing and design. They also are of great benefit for realistic simulation of surgical procedures. The objective of this study was therefore to characterize two groups of self-developed synthetic foam structures by static compressive testing and by microcomputed tomography. Two mineral fillers and varying amounts of a blowing agent were used to create different expansion behavior of the synthetic open-cell foams. The resulting compressive and morphometric properties thus differed within and also slightly between both groups. Apart from the structural anisotropy, the compressive and morphometric properties of the synthetic foam materials were shown to mirror the respective characteristics of human vertebral trabecular bone in good approximation. In conclusion, the artificial materials created can be used to manufacture valid synthetic bones for surgical training. Further, they provide novel possibilities for studying the relationship between trabecular bone microstructure and biomechanical properties. Copyright © 2017 Elsevier B.V. All rights reserved.

A trabecular metal implant 4 months after placement: clinical-histologic case report.

PubMed

Spinato, Sergio; Zaffe, Davide; Felice, Pietro; Checchi, Luigi; Wang, Hom-Lay

2014-02-01

The aim of this case report was to histologically evaluate the behavior of a trabecular metal (TM) implant composed of titanium and spatial 3-dimensional tantalum (Ta) trabeculae. This study is the first human histologic case report of this implant. A TM implant was placed in a 54-year-old woman exhibiting moderate chronic periodontitis. After periodontal treatment, the implant was inserted under favorable clinical conditions. Patient was not seen for 4 months because of unrelated breast reduction surgery. At the surgical reopening, periimplant inflammation affecting the coronal third of the implant was observed 4 months after implant placement. With patient's consent, the implant was removed for histologic analysis. Histology highlighted a greater amount of bone in close contact with Ta trabeculae than titanium surfaces. The finding of bone formation around the Ta trabeculae suggests that trabecular metal material promotes bone ingrowth for secondary implant stability. Additional evidence is needed to confirm this observation.

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

PubMed

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

2014-01-01

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

Cortical bone is more sensitive to alcohol dose effects than trabecular bone in the rat.

PubMed

Maurel, Delphine B; Boisseau, Nathalie; Benhamou, Claude-Laurent; Jaffré, Christelle

2012-10-01

While chronic alcohol consumption is known to decrease bone mineral content (BMC), bone mineral density (BMD), and negatively modify trabecular bone microarchitecture, the impact of alcohol on cortical microarchitecture is still unclear. The aim of this study was to investigate the effects of various doses of alcohol on bone density, trabecular and cortical parameters and bone strength in rats. Forty-eight male Wistar rats were divided into four groups: control (C), alcohol 25% v/v (A25), alcohol 30% v/v (A30) and alcohol 35% v/v (A35). Rats in the alcohol groups were fed a solution composed of ethanol and water for 17 weeks while the control group drank only water. Bone quality and quantity were evaluated through the analysis of density, trabecular and cortical bone microarchitectural parameters, osteocalcin and N-Telopeptide concentrations and a 3-point bending test. Bone density along with trabecular and cortical thickness were lower in alcohol groups compared to C. BMD was lower in A35 vs. A30 and cortical thickness was lower in A35 vs. A25 and A30. Pore number was increased by alcohol and the porosity was greater in A35 compared to C. N-Telopeptide concentration was decreased in alcohol groups compared to control whereas no differences were observed in osteocalcin concentrations. Maximal energy to failure was lower in A25 and A35 compared to C. Chronic ethanol consumption increases cortical bone damage in rats and may have detrimental effects on bone strength. These effects were dose-dependent, with greater negative effects proportionate to greater alcohol doses. Copyright © 2011 Société française de rhumatologie. Published by Elsevier SAS. All rights reserved.

Medication-taking behaviour in Bulgarian women with postmenopausal osteoporosis treated with denosumab or monthly oral bisphosphonates.

PubMed

Petranova, T; Boyanov, M; Shinkov, A; Petkova, R; Intorcia, M; Psachoulia, E

2017-12-21

Persistence with osteoporosis therapy is critical for fracture risk reduction. This observational study evaluated medication-taking behaviour of women with postmenopausal osteoporosis receiving denosumab or oral ibandronate in real-world clinical practice in Bulgaria. Compared with ibandronate, densoumab was associated with a lower discontinuation rate and greater increases in bone mineral density. Persistence with osteoporosis therapy is critical for fracture risk reduction and the effectiveness of such treatments may be reduced by low persistence. Alternative therapies such as denosumab may improve persistence. This study aimed to describe medication-taking behaviour in women with osteoporosis, prescribed denosumab or oral ibandronate, in Bulgarian clinical practice. This retrospective, observational, multicentre chart review (with up to 24 months follow-up) enrolled postmenopausal women initiating 6-monthly denosumab injection or monthly oral ibandronate treatment for osteoporosis between 1 October 2011 and 30 September 2012. Overall, 441 women were enrolled (224 had initiated denosumab, 217 had initiated ibandronate). At baseline, more women in the denosumab group than in the ibandronate group had a previous fracture (25.5 vs 17.5%; p = 0.043) and past exposure to osteoporosis therapy (19.6 vs 12.0%; p = 0.028). At 24 months, 4.5% of women receiving denosumab had discontinued therapy compared with 56.2% of women receiving ibandronate. Median time to discontinuation was longer in the denosumab group (729 days; interquartile range (IQR), 728.3-729.0) than in the ibandronate group (367 days; IQR, 354.0-484.8; p < 0.001). At 24 months, there were significantly greater changes in BMD T-scores at the lumbar spine (p < 0.001) and femoral neck (p < 0.001) in patients receiving denosumab than in those receiving ibandronate. At 24 months, persistence with denosumab was 98.7%. This real-world study demonstrates there is a low discontinuation rate and

Estrogen receptor α in osteocytes regulates trabecular bone formation in female mice.

PubMed

Kondoh, Shino; Inoue, Kazuki; Igarashi, Katsuhide; Sugizaki, Hiroe; Shirode-Fukuda, Yuko; Inoue, Erina; Yu, Taiyong; Takeuchi, Jun K; Kanno, Jun; Bonewald, Lynda F; Imai, Yuuki

2014-03-01

Estrogens are well known steroid hormones necessary to maintain bone health. In addition, mechanical loading, in which estrogen signaling may intersect with the Wnt/β-catenin pathway, is essential for bone maintenance. As osteocytes are known as the major mechanosensory cells embedded in mineralized bone matrix, osteocyte ERα deletion mice (ERα(ΔOcy/ΔOcy)) were generated by mating ERα floxed mice with Dmp1-Cre mice to determine the role of ERα in osteocytes. Trabecular bone mineral density of female, but not male ERα(ΔOcy/ΔOcy) mice was significantly decreased. Bone formation parameters in ERα(ΔOcy/ΔOcy) were significantly decreased while osteoclast parameters were unchanged. This suggests that ERα in osteocytes exerts osteoprotective function by positively controlling bone formation. To identify potential targets of ERα, gene array analysis of Dmp1-GFP osteocytes sorted by FACS from ERα(ΔOcy/ΔOcy) and control mice was performed. Gene expression microarray followed by gene ontology analyses revealed that osteocytes from ERα(ΔOcy/ΔOcy) highly expressed genes categorized in 'Secreted' when compared to control osteocytes. Among them, expression of Mdk and Sostdc1, both of which are Wnt inhibitors, was significantly increased without alteration of expression of the mature osteocyte markers such as Sost and β-catenin. Moreover, hindlimb suspension experiments showed that trabecular bone loss due to unloading was greater in ERα(ΔOcy/ΔOcy) mice without cortical bone loss. These data suggest that ERα in osteocytes has osteoprotective functions in trabecular bone formation through regulating expression of Wnt antagonists, but conversely plays a negative role in cortical bone loss due to unloading. Published by Elsevier Inc.

Pressure and shear stress in trabecular bone marrow during whole bone loading.

PubMed

Metzger, Thomas A; Schwaner, Stephen A; LaNeve, Anthony J; Kreipke, Tyler C; Niebur, Glen L

2015-09-18

Skeletal adaptation to mechanical loading is controlled by mechanobiological signaling. Osteocytes are highly responsive to applied strains, and are the key mechanosensory cells in bone. However, many cells residing in the marrow also respond to mechanical cues such as hydrostatic pressure and shear stress, and hence could play a role in skeletal adaptation. Trabecular bone encapsulates marrow, forming a poroelastic solid. According to the mechanical theory, deformation of the pores induces motion in the fluid-like marrow, resulting in pressure and velocity gradients. The latter results in shear stress acting between the components of the marrow. To characterize the mechanical environment of trabecular bone marrow in situ, pore pressure within the trabecular compartment of whole porcine femurs was measured with miniature pressure transducers during stress-relaxation and cyclic loading. Pressure gradients ranging from 0.013 to 0.46 kPa/mm were measured during loading. This range was consistent with calculated pressure gradients from continuum scale poroelastic models with the same permeability. Micro-scale computational fluid dynamics models created from computed tomography images were used to calculate the micromechanical stress in the marrow using the measured pressure differentials as boundary conditions. The volume averaged shear stress in the marrow ranged from 1.67 to 24.55 Pa during cyclic loading, which exceeds the mechanostimulatory threshold for mesenchymal lineage cells. Thus, the loading of bone through activities of daily living may be an essential component of bone marrow health and mechanobiology. Additional studies of cell-level interactions during loading in healthy and disease conditions will provide further incite into marrow mechanobiology. Copyright © 2015 Elsevier Ltd. All rights reserved.

Micro-CT characterization of human trabecular bone in osteogenesis imperfecta

NASA Astrophysics Data System (ADS)

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

2011-03-01

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

Trabecular bone class mapping across resolutions: translating methods from HR-pQCT to clinical CT

NASA Astrophysics Data System (ADS)

Valentinitsch, Alexander; Fischer, Lukas; Patsch, Janina M.; Bauer, Jan; Kainberger, Franz; Langs, Georg; DiFranco, Matthew

2015-03-01

Quantitative assessment of 3D bone microarchitecture in high-resolution peripheral quantitative computed tomography (HR-pQCT) has shown promise in fracture risk assessment and biomechanics, but is limited to the distal radius and tibia. Trabecular microarchitecture classes (TMACs), based on voxel-wise clustering texture and structure tensor features in HRpQCT, is extended in this paper to quantify trabecular bone classes in clinical multi-detector CT (MDCT) images. Our comparison of TMACs in 12 cadaver radii imaged using both HRpQCT and MDCT yields a mean Dice score of up to 0.717+/-0.40 and visually concordant bone quality maps. Further work to develop clinically viable bone quantitative imaging using HR-pQCT validation could have a significant impact on overall bone health assessment.

Bone quality assessment for total hip arthroplasty with intraoperative trabecular torque measurements.

PubMed

Klotz, Matthias C M; Beckmann, Nicholas A; Bitsch, Rudi G; Seebach, Elisabeth; Reiner, Tobias; Jäger, Sebastian

2014-11-13

In cases of poor bone quality, intraoperative torque measurement might be an alternative to preoperative dual-energy X-ray absorptiometry (DXA) to assess bone quality in total hip arthroplasty (THA). Trabecular peak torque measurement was applied in 14 paired fresh frozen human femurs. Here, a 6.5 × 23 mm wingblade was inserted into the proximal femur without harming the lateral cortical bone. Further tests of the proximal femur also evaluated bone strength (DXA, micro-computed tomography (μCT), monoaxial compression test), and the results were compared to the trabecular torque measurement. Student's t-test was used to compare the values of the groups. Pearson product-moment was applied to correlate the values of the peak torque measurement with the bone strength measured by DXA, μCT, and monoaxial compression test. In the femoral head, the mean trabecular peak torque was 4.38 ± 1.86 Nm. These values showed a strong correlation with the values of the DXA, the μCT, and the biomechanical load test (Pearson's product-moment: DXA: 0.86, μCT-BMD: 0.80, load test: 0.85). Furthermore, the torque measurement showed a more pronounced correlation with the biomechanical load test compared to the DXA. The use of this method provides highly diagnostic information about bone quality. Since the approach was adjusted for THA, no harm of the lateral bone stock will result from this measurement during surgery. The results of this initial study employing small sample sizes indicate that this new method is as sensitive as DXA in predicting bone quality and may function as an intraoperative alternative to DXA in THA. Nevertheless, before this method will turn into clinical use, more research and clinical trials are necessary.

Ethnic differences in trabecular meshwork height by optical coherence tomography.

PubMed

Chen, Rebecca I; Barbosa, Diego T; Hsu, Chi-Hsin; Porco, Travis C; Lin, Shan C

2015-04-01

Differences in ocular anatomy may contribute to ethnic differences in glaucoma risk. Because the trabecular meshwork (TM) plays an important role in aqueous outflow, its anatomy in relation to at-risk populations may provide insight into a potential contributor to elevated intraocular pressure and thus to probability of glaucoma development. To investigate whether differences exist in TM height between ethnic groups. This prospective study took place from January 1, 2012, to December 31, 2013. Adult patients who self-reported as being of white, Asian, Hispanic, or African American ethnicity were recruited from ophthalmology clinics at the University of California, San Francisco. The TM height was assessed using spectral-domain anterior segment optical coherence tomography. Trabecular meshwork height was measured from the scleral spur to the Schwalbe line. We hypothesized that ethnicities with a higher prevalence of glaucoma would tend to have shorter TM heights. We collected data from 460 eyes of 291 participants after excluding 34 optical coherence tomographic scans owing to poor image quality. The final sample was 32.2% white, 45.1% Asian, 10.5% African American, and 12.1% Hispanic. There were 64.2% women, and the mean age was 68.1 years. The mean (SD) TM height among all eyes included in the study was 836 (131) μm. The mean (SD) TM height was characterized among white (851 [131] μm), Asian (843 [126] μm), Hispanic (822 [147] μm), and African American (771 [118] μm) persons. Ethnicity was not associated with TM height overall (P = .23, linear mixed regression model). However, the TM heights of African American participants (771 μm) were shorter than those of white (851 μm; adjusted difference 95% CI, -119.8 to -8.1; P = .02) and Asian (843 μm; adjusted difference 95% CI, -117.4 to -10.8; P = .02) participants. Although TM height is not associated with ethnicity overall, African American individuals have shorter TM heights compared with Asian and white

Theoretical Bounds for the Influence of Tissue-Level Ductility on the Apparent-Level Strength of Human Trabecular Bone

PubMed Central

Nawathe, Shashank; Juillard, Frédéric; Keaveny, Tony M.

2015-01-01

The role of tissue-level post-yield behavior on the apparent-level strength of trabecular bone is a potentially important aspect of bone quality. To gain insight into this issue, we compared the apparent-level strength of trabecular bone for the hypothetical cases of fully brittle versus fully ductile failure behavior of the trabecular tissue. Twenty human cadaver trabecular bone specimens (5 mm cube; BV/TV = 6–36%) were scanned with micro-CT to create 3D finite element models (22-micron element size). For each model, apparent-level strength was computed assuming either fully brittle (fracture with no tissue ductility) or fully ductile (yield with no tissue fracture) tissue-level behaviors. We found that the apparent-level ultimate strength for the brittle behavior was only about half the value of the apparent-level 0.2%-offset yield strength for the ductile behavior, and the ratio of these brittle to ductile strengths was almost constant (mean ± SD = 0.56 ± 0.02; n=20; R2 = 0.99 between the two measures). As a result of this small variation, although the ratio of brittle to ductile strengths was positively correlated with the bone volume fraction (R2=0.44, p=0.01) and structure model index (SMI, R2=0.58, p<0.01), these effects were small. Mechanistically, the fully ductile behavior resulted in a much higher apparent-level strength because in this case about 16-fold more tissue was required to fail than for the fully brittle behavior; also, there was more tensile- than compressive-mode of failure at the tissue level for the fully brittle behavior. We conclude that, in theory, the apparent-level strength behavior of human trabecular bone can vary appreciably depending on whether the tissue fails in a fully ductile versus fully brittle manner, and this effect is largely constant despite appreciable variations in bone volume fraction and microarchitecture. PMID:23497799

Clopidogrel (Plavix), a P2Y12 receptor antagonist, inhibits bone cell function in vitro and decreases trabecular bone in vivo.

PubMed

Syberg, Susanne; Brandao-Burch, Andrea; Patel, Jessal J; Hajjawi, Mark; Arnett, Timothy R; Schwarz, Peter; Jorgensen, Niklas R; Orriss, Isabel R

2012-11-01

Clopidogrel (Plavix), a selective P2Y(12) receptor antagonist, is widely prescribed to reduce the risk of heart attack and stroke and acts via the inhibition of platelet aggregation. Accumulating evidence now suggests that extracellular nucleotides, signaling through P2 receptors, play a significant role in bone, modulating both osteoblast and osteoclast function. In this study, we investigated the effects of clopidogrel treatment on (1) bone cell formation, differentiation, and activity in vitro; and (2) trabecular and cortical bone parameters in vivo. P2Y(12) receptor expression by osteoblasts and osteoclasts was confirmed using qPCR and Western blotting. Clopidogrel at 10 µM and 25 µM inhibited mineralized bone nodule formation by 50% and >85%, respectively. Clopidogrel slowed osteoblast proliferation with dose-dependent decreases in cell number (25% to 40%) evident in differentiating osteoblasts (day 7). A single dose of 10 to 25 µM clopidogrel to mature osteoblasts also reduced cell viability. At 14 days, ≥10 µM clopidogrel decreased alkaline phosphatase (ALP) activity by ≤70% and collagen formation by 40%, while increasing adipocyte formation. In osteoclasts, ≥1 µM clopidogrel inhibited formation, viability and resorptive activity. Twenty-week-old mice (n = 10-12) were ovariectomized or sham treated and dosed orally with clopidogrel (1 mg/kg) or vehicle (NaCl) daily for 4 weeks. Dual-energy X-ray absorptiometry (DXA) analysis showed clopidogrel-treated animals had decreases of 2% and 4% in whole-body and femoral bone mineral density (BMD), respectively. Detailed analysis of trabecular and cortical bone using micro-computed tomography (microCT) showed decreased trabecular bone volume in the tibia (24%) and femur (18%) of clopidogrel-treated mice. Trabecular number was reduced 20%, while trabecular separation was increased up to 15%. Trabecular thickness and cortical bone parameters were unaffected. Combined, these findings indicate that long

Effects of immediate and delayed loading on peri-implant trabecular structures: a cone beam CT evaluation.

PubMed

Huang, Yan; Van Dessel, Jeroen; Liang, Xin; Depypere, Maarten; Zhong, Weijian; Ma, Guowu; Lambrichts, Ivo; Maes, Frederik; Jacobs, Reinhilde

2014-12-01

To develop a method for characterizing trabecular bone microarchitecture using cone beam computed tomography (CBCT) and to evaluate trabecular bone changes after rehabilitation using immediate versus delayed implant protocols. Six mongrel dogs randomly received 27 titanium implants in the maxillary incisor or mandibular premolar areas, following one of four protocols: (1) normal extraction socket healing; (2) immediate implant placement and immediate loading; (3) delayed implant placement and delayed loading; (4) delayed implant placement and immediate loading. The animals were euthanized at 8 weeks, and block biopsies were scanned using high resolution CBCT. Standard bone structural variables were assessed in coronal, middle, and apical levels. Coronal and middle regions had more compact, more platelike, and thicker trabeculae. Protocols (2), (3), and (4) had significantly higher values (p < 0.001) than protocol (1) for bone surface density, bone surface volume ratio, and connectivity density, while significantly lower values (p < 0.001) were found for trabecular separation and fractal dimension. However, protocols (2), (3), and (4) did not show significantly different bone remodeling. Compared with normal extraction healing, the implant protocols have an improved bone structural integration. Results do not suggest a different bone remodeling pattern when a delayed versus an immediate implant protocol is used. © 2013 Wiley Periodicals, Inc.

Effect of swimming exercise on three-dimensional trabecular bone microarchitecture in ovariectomized rats.

PubMed

Ju, Yong-In; Sone, Teruki; Ohnaru, Kazuhiro; Tanaka, Kensuke; Fukunaga, Masao

2015-11-01

Swimming is generally considered ineffective for increasing bone mass in humans, at least compared with weight-bearing sports. However, swimming exercise has sometimes been shown to have a strong positive effect on bone mass in small animals. This study investigated the effects of swimming on bone mass, strength, and microarchitecture in ovariectomized (OVX) rats. OVX or sham operations were performed on 18-wk-old female Fisher 344 rats. Rats were randomly divided into four groups: sham sedentary (Sham-CON), sham swimming exercised (Sham-SWI), OVX sedentary (OVX-CON), and OVX swimming exercised (OVX-SWI). Rats in exercise groups performed swimming in a water bath for 60 min/day, 5 days/wk, for 12 wk. Bone mineral density (BMD) in right femurs was analyzed using dual-energy X-ray absorptiometry. Three-dimensional trabecular architecture at the distal femoral metaphysis was analyzed using microcomputed tomography (μCT). Geometrical properties of diaphyseal cortical bone were evaluated in the midfemoral region using μCT. The biomechanical properties of femurs were analyzed using three-point bending. Femoral BMD was significantly decreased following ovariectomy. This change was suppressed by swimming. Trabecular bone thickness, number, and connectivity were decreased by ovariectomy, whereas structure model index (i.e., ratio of rod-like to plate-like trabeculae) increased. These changes were also suppressed by swimming exercise. Femurs displayed greater cortical width and maximum load in SWI groups than in CON groups. Together, these results demonstrate that swimming exercise drastically alleviated both OVX-induced decreases in bone mass and mechanical strength and the deterioration of trabecular microarchitecture in rat models of osteoporosis. Copyright © 2015 the American Physiological Society.

The effect of long-term bisphosphonate therapy on trabecular bone strength and microcrack density

PubMed Central

Jin, A.; Cobb, J.; Hansen, U.; Bhattacharya, R.; Reinhard, C.; Vo, N.; Atwood, R.; Li, J.; Karunaratne, A.; Wiles, C.

2017-01-01

Objectives Bisphosphonates (BP) are the first-line treatment for preventing fragility fractures. However, concern regarding their efficacy is growing because bisphosphonate is associated with over-suppression of remodelling and accumulation of microcracks. While dual-energy X-ray absorptiometry (DXA) scanning may show a gain in bone density, the impact of this class of drug on mechanical properties remains unclear. We therefore sought to quantify the mechanical strength of bone treated with BP (oral alendronate), and correlate data with the microarchitecture and density of microcracks in comparison with untreated controls. Methods Trabecular bone from hip fracture patients treated with BP (n = 10) was compared with naïve fractured (n = 14) and non-fractured controls (n = 6). Trabecular cores were synchrotron scanned and micro-CT scanned for microstructural analysis, including quantification of bone volume fraction, microarchitecture and microcracks. The specimens were then mechanically tested in compression. Results BP bone was 28% lower in strength than untreated hip fracture bone, and 48% lower in strength than non-fractured control bone (4.6 MPa vs 6.4 MPa vs 8.9 MPa). BP-treated bone had 24% more microcracks than naïve fractured bone and 51% more than non-fractured control (8.12/cm2 vs 6.55/cm2 vs 5.25/cm2). BP and naïve fracture bone exhibited similar trabecular microarchitecture, with significantly lower bone volume fraction and connectivity than non-fractured controls. Conclusion BP therapy had no detectable mechanical benefit in the specimens examined. Instead, its use was associated with substantially reduced bone strength. This low strength may be due to the greater accumulation of microcracks and a lack of any discernible improvement in bone volume or microarchitecture. This preliminary study suggests that the clinical impact of BP-induced microcrack accumulation may be significant. Cite this article: A. Jin, J. Cobb, U. Hansen, R. Bhattacharya, C

Association of larger holes in the trabecular bone at the distal radius in postmenopausal women with type 2 diabetes mellitus compared to controls.

PubMed

Pritchard, Janet M; Giangregorio, Lora M; Atkinson, Stephanie A; Beattie, Karen A; Inglis, Dean; Ioannidis, George; Punthakee, Zubin; Adachi, J D; Papaioannou, Alexandra

2012-01-01

Adults with type 2 diabetes mellitus (DM) have an elevated fracture risk despite normal areal bone mineral density (aBMD). The study objective was to compare trabecular bone microarchitecture of postmenopausal women with type 2 DM and women without type 2 DM. An extremity 1T magnetic resonance imaging system was used to acquire axial images (195 × 195 × 1,000 μm(3) voxel size) of the distal radius of women recruited from outpatient clinics or by community advertisement. Image segmentation yielded geometric, topologic, and stereologic outcomes, i.e., number and size of trabecular bone network holes (marrow spaces), endosteal area, trabecular bone volume fraction, nodal and branch density, and apparent trabecular thickness, separation, and number. Lumbar spine (LS) and proximal femur BMD were measured with dual x-ray absorptiometry. Microarchitectural differences were assessed using linear regression and adjusted for percent body fat, ethnicity, timed up-and-go test, Charlson Index, and calcium and vitamin D intake; aBMD differences were adjusted for body mass index (BMI). Women with type 2 DM (n = 30, mean ± SD age 71.0 ± 4.8 years) had larger holes (+13.3%; P = 0.001) within the trabecular bone network than women without type 2 DM (n = 30, mean ± SD age 70.7 ± 4.9 years). LS aBMD was greater in women with type 2 DM; however, after adjustment for BMI, LS aBMD did not differ between groups. In women with type 2 DM, the average hole size within the trabecular bone network at the distal radius is greater compared to controls. This may explain the elevated fracture risk in this population. Copyright © 2012 by the American College of Rheumatology.

Freeze-thaw decellularization of the trabecular meshwork in an ex vivo eye perfusion model

PubMed Central

Dang, Yalong; Waxman, Susannah; Wang, Chao; Jensen, Adrianna; Loewen, Ralitsa T.; Bilonick, Richard A.

2017-01-01

Objective The trabecular meshwork (TM) is the primary substrate of outflow resistance in glaucomatous eyes. Repopulating diseased TM with fresh, functional TM cells might be a viable therapeutic approach. Decellularized TM scaffolds have previously been produced by ablating cells with suicide gene therapy or saponin, which risks incomplete cell removal or dissolution of the extracellular matrix, respectively. We hypothesized that improved trabecular meshwork cell ablation would result from freeze-thaw cycles compared to chemical treatment. Materials and Methods We obtained 24 porcine eyes from a local abattoir, dissected and mounted them in an anterior segment perfusion within two hours of sacrifice. Intraocular pressure (IOP) was recorded continuously by a pressure transducer system. After 72 h of IOP stabilization, eight eyes were assigned to freeze-thaw (F) ablation (−80 °C × 2), to 0.02% saponin (S) treatment, or the control group (C), respectively. The TM was transduced with an eGFP expressing feline immunodeficiency viral (FIV) vector and tracked via fluorescent microscopy to confirm ablation. Following treatment, the eyes were perfused with standard tissue culture media for 180 h. TM histology was assessed by hematoxylin and eosin staining. TM viability was evaluated by a calcein AM/propidium iodide (PI) assay. The TM extracellular matrix was stained with Picro Sirius Red. We measured IOP and modeled it with a linear mixed effects model using a B-spline function of time with five degrees of freedom. Results F and S experienced a similar IOP reduction of 30% from baseline (P = 0.64). IOP reduction of about 30% occurred in F within 24 h and in S within 48 h. Live visualization of eGFP demonstrated that F conferred a complete ablation of all TM cells and only a partial ablation in S. Histological analysis and Picro Sirius staining confirmed that no TM cells survived in F while the extracellular matrix remained. The viability assay showed very low

Anisotropic analysis of trabecular architecture in human femur bone radiographs using quaternion wavelet transforms.

PubMed

Sangeetha, S; Sujatha, C M; Manamalli, D

2014-01-01

In this work, anisotropy of compressive and tensile strength regions of femur trabecular bone are analysed using quaternion wavelet transforms. The normal and abnormal femur trabecular bone radiographic images are considered for this study. The sub-anatomic regions, which include compressive and tensile regions, are delineated using pre-processing procedures. These delineated regions are subjected to quaternion wavelet transforms and statistical parameters are derived from the transformed images. These parameters are correlated with apparent porosity, which is derived from the strength regions. Further, anisotropy is also calculated from the transformed images and is analyzed. Results show that the anisotropy values derived from second and third phase components of quaternion wavelet transform are found to be distinct for normal and abnormal samples with high statistical significance for both compressive and tensile regions. These investigations demonstrate that architectural anisotropy derived from QWT analysis is able to differentiate normal and abnormal samples.

Exploring the Bone Proteome to Help Explain Altered Bone Remodeling and Preservation of Bone Architecture and Strength in Hibernating Marmots.

PubMed

Doherty, Alison H; Roteliuk, Danielle M; Gookin, Sara E; McGrew, Ashley K; Broccardo, Carolyn J; Condon, Keith W; Prenni, Jessica E; Wojda, Samantha J; Florant, Gregory L; Donahue, Seth W

2016-01-01

Periods of physical inactivity increase bone resorption and cause bone loss and increased fracture risk. However, hibernating bears, marmots, and woodchucks maintain bone structure and strength, despite being physically inactive for prolonged periods annually. We tested the hypothesis that bone turnover rates would decrease and bone structural and mechanical properties would be preserved in hibernating marmots (Marmota flaviventris). Femurs and tibias were collected from marmots during hibernation and in the summer following hibernation. Bone remodeling was significantly altered in cortical and trabecular bone during hibernation with suppressed formation and no change in resorption, unlike the increased bone resorption that occurs during disuse in humans and other animals. Trabecular bone architecture and cortical bone geometrical and mechanical properties were not different between hibernating and active marmots, but bone marrow adiposity was significantly greater in hibernators. Of the 506 proteins identified in marmot bone, 40 were significantly different in abundance between active and hibernating marmots. Monoaglycerol lipase, which plays an important role in fatty acid metabolism and the endocannabinoid system, was 98-fold higher in hibernating marmots compared with summer marmots and may play a role in regulating the changes in bone and fat metabolism that occur during hibernation.

Finite element micro-modelling of a human ankle bone reveals the importance of the trabecular network to mechanical performance: new methods for the generation and comparison of 3D models.

PubMed

Parr, W C H; Chamoli, U; Jones, A; Walsh, W R; Wroe, S

2013-01-04

Most modelling of whole bones does not incorporate trabecular geometry and treats bone as a solid non-porous structure. Some studies have modelled trabecular networks in isolation. One study has modelled the performance of whole human bones incorporating trabeculae, although this required considerable computer resources and purpose-written code. The difference between mechanical behaviour in models that incorporate trabecular geometry and non-porous models has not been explored. The ability to easily model trabecular networks may shed light on the mechanical consequences of bone loss in osteoporosis and remodelling after implant insertion. Here we present a Finite Element Analysis (FEA) of a human ankle bone that includes trabecular network geometry. We compare results from this model with results from non-porous models and introduce protocols achievable on desktop computers using widely available softwares. Our findings show that models including trabecular geometry are considerably stiffer than non-porous whole bone models wherein the non-cortical component has the same mass as the trabecular network, suggesting inclusion of trabecular geometry is desirable. We further present new methods for the construction and analysis of 3D models permitting: (1) construction of multi-property, non-porous models wherein cortical layer thickness can be manipulated; (2) maintenance of the same triangle network for the outer cortical bone surface in both 3D reconstruction and non-porous models allowing exact replication of load and restraint cases; and (3) creation of an internal landmark point grid allowing direct comparison between 3D FE Models (FEMs). Copyright © 2012 Elsevier Ltd. All rights reserved.

Two new regions of interest to evaluate separately cortical and trabecular BMD in the proximal femur using DXA.

PubMed

Prevrhal, Sven; Meta, Margarita; Genant, Harry K

2004-01-01

To differentiate changes in trabecular and cortical bone density at a skeletal site bearing body weight, the main goal of this retrospective study was to develop and characterize two new regions of interest (ROIs) for DXA at the hip, one mainly focusing on trabecular bone and another mainly focusing on cortical bone. Specific aims were to maximize the precision of the ROIs and to characterize their usefulness for monitoring age-related bone loss and discriminating controls from fracture cases in a cross-sectional study population and to compare them with earlier ROIs designed by our group. The study used populations from two different previous studies conducted in our laboratory, with one comprising cohorts of healthy premenopausal women, healthy postmenopausal women, and postmenopausal osteoporotic women with at least one spinal fracture (Spine Fx Study) and the other one comprising two cohorts of age-matched postmenopausal women, in whom cases had sustained a hip fracture (Hip Fx study). The new ROI for trabecular bone (CIRCROI) tries to improve on the earlier custom-designed Central ROI, which was also targeted at trabecular bone. CIRCROI consists of an approximate largest circle that can fit inside the femoral proximal metaphysis without touching the superior and inferior endocortical walls. The new ROI for cortical bone (CORTROI) at a site bearing body weight is defined as a horizontal rectangular box crossing the femoral shaft below the lesser trochanter. CORTROI BMD cohort means were significantly higher than all other ROIs, and CIRCROI BMD cohort means were lower than standard ROIs with the exception of Ward's ROI. CIRCROI BMD was highly correlated with total femur BMD ( r=0.94) and Central BMD ( r=0.93), whereas CORTROI BMD correlations were lower (highest with total femur BMD ( r=0.86)). Fracture discrimination odds ratios (ORs) of all ROIs were significant for the Hip Fx Study, with CIRCROI BMD having the highest, and CORTROI BMD the lowest, OR (4.83 and

Characterizing trabecular bone structure for assessing vertebral fracture risk on volumetric quantitative computed tomography

NASA Astrophysics Data System (ADS)

Nagarajan, Mahesh B.; Checefsky, Walter A.; Abidin, Anas Z.; Tsai, Halley; Wang, Xixi; Hobbs, Susan K.; Bauer, Jan S.; Baum, Thomas; Wismüller, Axel

2015-03-01

While the proximal femur is preferred for measuring bone mineral density (BMD) in fracture risk estimation, the introduction of volumetric quantitative computed tomography has revealed stronger associations between BMD and spinal fracture status. In this study, we propose to capture properties of trabecular bone structure in spinal vertebrae with advanced second-order statistical features for purposes of fracture risk assessment. For this purpose, axial multi-detector CT (MDCT) images were acquired from 28 spinal vertebrae specimens using a whole-body 256-row CT scanner with a dedicated calibration phantom. A semi-automated method was used to annotate the trabecular compartment in the central vertebral slice with a circular region of interest (ROI) to exclude cortical bone; pixels within were converted to values indicative of BMD. Six second-order statistical features derived from gray-level co-occurrence matrices (GLCM) and the mean BMD within the ROI were then extracted and used in conjunction with a generalized radial basis functions (GRBF) neural network to predict the failure load of the specimens; true failure load was measured through biomechanical testing. Prediction performance was evaluated with a root-mean-square error (RMSE) metric. The best prediction performance was observed with GLCM feature `correlation' (RMSE = 1.02 ± 0.18), which significantly outperformed all other GLCM features (p < 0.01). GLCM feature correlation also significantly outperformed MDCTmeasured mean BMD (RMSE = 1.11 ± 0.17) (p< 10-4). These results suggest that biomechanical strength prediction in spinal vertebrae can be significantly improved through characterization of trabecular bone structure with GLCM-derived texture features.

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

PubMed

Matarazzo, Stacey A

2015-01-01

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

Postmenopausal women with osteoarthritis and osteoporosis show different ultrastructural characteristics of trabecular bone of the femoral head.

PubMed

Shen, Yun; Zhang, Zi-Ming; Jiang, Sheng-Dan; Jiang, Lei-Sheng; Dai, Li-Yang

2009-04-09

Osteoporosis (OP) and osteoarthritis (OA) are public health diseases affecting the quality of life of the elderly, and bring about a heavy burden to the society and family of patients. It has been debated whether or not there is an inverse relationship between these two disorders. To compare the exact difference in bone tissue structure between osteoporosis and osteoarthritis, we observed the ultrastructure of trabecular bone from the femoral heads using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). A total of 15 femoral head specimens from postmenopausal women were collected during the procedures of total or hemi hip replacement (OP, n = 8; OA, n = 7). The morphologic structure of the trabecular bone, collagen fibers, resorption lacuna and osteoblasts were observed. Under SEM, osteoporotic trabeculae appeared to be thinning, tapering, breaking and perforating. A number of resorption lacunae of various shapes were seen on the surface of the trabeculum. The collagen fibers of lacuna were resorbed. On occasion, naked granular bone crystals could be found. In the OA group, the trabecular bone looked thick with integrated structure. Reticular and granular new bone could be found. The trabeculum was covered by well-arranged collagen fibers around the resorption lacuna. In the OP group, under TEM, marginal collagen fibers were observed to be aligned loosely with enlarged spaces. A few inactive osteoblasts and no inflammatory cells were seen. In the OA group, the collagen fibers inside the trabeculum were arranged in a dense manner with many active osteoblasts and inflammatory cells infiltrating the matrix. We found significant differences in the trabecular bone, collagen fibers, lacunae and osteoblasts between postmenopausal women with OP and OA. These findings support the hypothesis that there is an inverse relationship between OP and OA.

Postmenopausal women with osteoarthritis and osteoporosis show different ultrastructural characteristics of trabecular bone of the femoral head

PubMed Central

Shen, Yun; Zhang, Zi-Ming; Jiang, Sheng-Dan; Jiang, Lei-Sheng; Dai, Li-Yang

2009-01-01

Background Osteoporosis (OP) and osteoarthritis (OA) are public health diseases affecting the quality of life of the elderly, and bring about a heavy burden to the society and family of patients. It has been debated whether or not there is an inverse relationship between these two disorders. Methods To compare the exact difference in bone tissue structure between osteoporosis and osteoarthritis, we observed the ultrastructure of trabecular bone from the femoral heads using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). A total of 15 femoral head specimens from postmenopausal women were collected during the procedures of total or hemi hip replacement (OP, n = 8; OA, n = 7). The morphologic structure of the trabecular bone, collagen fibers, resorption lacuna and osteoblasts were observed. Results Under SEM, osteoporotic trabeculae appeared to be thinning, tapering, breaking and perforating. A number of resorption lacunae of various shapes were seen on the surface of the trabeculum. The collagen fibers of lacuna were resorbed. On occasion, naked granular bone crystals could be found. In the OA group, the trabecular bone looked thick with integrated structure. Reticular and granular new bone could be found. The trabeculum was covered by well-arranged collagen fibers around the resorption lacuna. In the OP group, under TEM, marginal collagen fibers were observed to be aligned loosely with enlarged spaces. A few inactive osteoblasts and no inflammatory cells were seen. In the OA group, the collagen fibers inside the trabeculum were arranged in a dense manner with many active osteoblasts and inflammatory cells infiltrating the matrix. Conclusion We found significant differences in the trabecular bone, collagen fibers, lacunae and osteoblasts between postmenopausal women with OP and OA. These findings support the hypothesis that there is an inverse relationship between OP and OA. PMID:19356253

The relationship between dental implant stability and trabecular bone structure using cone-beam computed tomography

PubMed Central

2016-01-01

Purpose The objective of this study was to investigate the relationships between primary implant stability as measured by impact response frequency and the structural parameters of trabecular bone using cone-beam computed tomography(CBCT), excluding the effect of cortical bone thickness. Methods We measured the impact response of a dental implant placed into swine bone specimens composed of only trabecular bone without the cortical bone layer using an inductive sensor. The peak frequency of the impact response spectrum was determined as an implant stability criterion (SPF). The 3D microstructural parameters were calculated from CT images of the bone specimens obtained using both micro-CT and CBCT. Results SPF had significant positive correlations with trabecular bone structural parameters (BV/TV, BV, BS, BSD, Tb.Th, Tb.N, FD, and BS/BV) (P<0.01) while SPF demonstrated significant negative correlations with other microstructural parameters (Tb.Sp, Tb.Pf, and SMI) using micro-CT and CBCT (P<0.01). Conclusions There was an increase in implant stability prediction by combining BV/TV and SMI in the stepwise forward regression analysis. Bone with high volume density and low surface density shows high implant stability. Well-connected thick bone with small marrow spaces also shows high implant stability. The combination of bone density and architectural parameters measured using CBCT can predict the implant stability more accurately than the density alone in clinical diagnoses. PMID:27127692

Cross-sex testosterone therapy in ovariectomized mice: addition of low-dose estrogen preserves bone architecture.

PubMed

Goetz, Laura G; Mamillapalli, Ramanaiah; Devlin, Maureen J; Robbins, Amy E; Majidi-Zolbin, Masoumeh; Taylor, Hugh S

2017-11-01

Cross-sex hormone therapy (XHT) is widely used by transgender people to alter secondary sex characteristics to match their desired gender presentation. Here, we investigate the long-term effects of XHT on bone health using a murine model. Female mice underwent ovariectomy at either 6 or 10 wk and began weekly testosterone or vehicle injections. Dual-energy X-ray absorptiometry (DXA) was performed (20 wk) to measure bone mineral density (BMD), and microcomputed tomography was performed to compare femoral cortical and trabecular bone architecture. The 6-wk testosterone group had comparable BMD with controls by DXA but reduced bone volume fraction, trabecular number, and cortical area fraction and increased trabecular separation by microcomputed tomography. Ten-week ovariectomy/XHT maintained microarchitecture, suggesting that estrogen is critical for bone acquisition during adolescence and that late, but not early, estrogen loss can be sufficiently replaced by testosterone alone. Given these findings, we then compared effects of testosterone with effects of weekly estrogen or combined testosterone/low-dose estrogen treatment after a 6-wk ovariectomy. Estrogen treatment increased spine BMD and microarchitecture, including bone volume fraction, trabecular number, trabecular thickness, and connectivity density, and decreased trabecular separation. Combined testosterone-estrogen therapy caused similar increases in femur and spine BMD and improved architecture (increased bone volume fraction, trabecular number, trabecular thickness, and connectivity density) to estrogen therapy and were superior compared with mice treated with testosterone only. These results demonstrate estradiol is critical for bone acquisition and suggest a new cross-sex hormone therapy adding estrogens to testosterone treatments with potential future clinical implications for treating transgender youth or men with estrogen deficiency. Copyright © 2017 the American Physiological Society.

Scaling relations between trabecular bone volume fraction and microstructure at different skeletal sites.

PubMed

Räth, Christoph; Baum, Thomas; Monetti, Roberto; Sidorenko, Irina; Wolf, Petra; Eckstein, Felix; Matsuura, Maiko; Lochmüller, Eva-Maria; Zysset, Philippe K; Rummeny, Ernst J; Link, Thomas M; Bauer, Jan S

2013-12-01

In this study, we investigated the scaling relations between trabecular bone volume fraction (BV/TV) and parameters of the trabecular microstructure at different skeletal sites. Cylindrical bone samples with a diameter of 8mm were harvested from different skeletal sites of 154 human donors in vitro: 87 from the distal radius, 59/69 from the thoracic/lumbar spine, 51 from the femoral neck, and 83 from the greater trochanter. μCT images were obtained with an isotropic spatial resolution of 26μm. BV/TV and trabecular microstructure parameters (TbN, TbTh, TbSp, scaling indices (< > and σ of α and αz), and Minkowski Functionals (Surface, Curvature, Euler)) were computed for each sample. The regression coefficient β was determined for each skeletal site as the slope of a linear fit in the double-logarithmic representations of the correlations of BV/TV versus the respective microstructure parameter. Statistically significant correlation coefficients ranging from r=0.36 to r=0.97 were observed for BV/TV versus microstructure parameters, except for Curvature and Euler. The regression coefficients β were 0.19 to 0.23 (TbN), 0.21 to 0.30 (TbTh), -0.28 to -0.24 (TbSp), 0.58 to 0.71 (Surface) and 0.12 to 0.16 (<α>), 0.07 to 0.11 (<αz>), -0.44 to -0.30 (σ(α)), and -0.39 to -0.14 (σ(αz)) at the different skeletal sites. The 95% confidence intervals of β overlapped for almost all microstructure parameters at the different skeletal sites. The scaling relations were independent of vertebral fracture status and similar for subjects aged 60-69, 70-79, and >79years. In conclusion, the bone volume fraction-microstructure scaling relations showed a rather universal character. © 2013.

Transition to nonpenetrating trabecular surgery: sclerotrabeculectomy.

PubMed

Sourdille, Philippe; Santiago, Pierre Yves; Bresson-Dumont, Hélène

2002-12-01

A transition from trabeculectomy to nonpenetrating trabecular surgery (NPTS) is proposed under the name of sclerotrabeculectomy. The technique, which is aimed at facilitating the transition to NPTS, is a modification of both penetrating and nonpenetrating techniques. Sclerotrabeculectomy uses a more superficial sclerokeratectomy than NPTS to avoid the risk of perforation. A minitrabeculectomy with cross-linked hyaluronate implant insertion in the sclerokeratectomy site is performed, with several sutures placed in the superficial flap. The sclerokeratectomy site is filled with cohesive viscoelastic substance to avoid a flat or shallow anterior chamber. Using this technique, it is possible to move to NPTS by finding the pre-Descemet's plane in front of the scleral spur and removing the external trabeculum. In case of accidental microperforation of Descemet's plane, the operation is finished as a standard sclerotrabeculectomy with no risk to the patient's eye. A safe transition can thus be achieved. Initial clinical results demonstrate excellent lowering of intraocular pressure without significant complications.

New microscale constitutive model of human trabecular bone based on depth sensing indentation technique.

PubMed

Pawlikowski, Marek; Jankowski, Krzysztof; Skalski, Konstanty

2018-05-30

A new constitutive model for human trabecular bone is presented in the present study. As the model is based on indentation tests performed on single trabeculae it is formulated in a microscale. The constitutive law takes into account non-linear viscoelasticity of the tissue. The elastic response is described by the hyperelastic Mooney-Rivlin model while the viscoelastic effects are considered by means of the hereditary integral in which stress depends on both time and strain. The material constants in the constitutive equation are identified on the basis of the stress relaxation tests and the indentation tests using curve-fitting procedure. The constitutive model is implemented into finite element package Abaqus ® by means of UMAT subroutine. The curve-fitting error is low and the viscoelastic behaviour of the tissue predicted by the proposed constitutive model corresponds well to the realistic response of the trabecular bone. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

Exercise reverses pain-related weight asymmetry and differentially modulates trabecular bone microarchitecture in a rat model of osteoarthritis.

PubMed

Cormier, Jim; Cone, Katherine; Lanpher, Janell; Kinens, Abigail; Henderson, Terry; Liaw, Lucy; Bilsky, Edward J; King, Tamara; Rosen, Clifford J; Stevenson, Glenn W

2017-07-01

There is great interest in developing and utilizing non-pharmacological/non-invasive forms of therapy for osteoarthritis (OA) pain including exercise and other physical fitness regimens. The present experiments determined the effects of prior wheel running on OA-induced weight asymmetry and trabecular bone microarchitecture. Wheel running included 7 or 21days of prior voluntary access to wheels followed by OA induction, followed by 21days post-OA access to wheels. OA was induced with monosodium iodoacetate (MIA), and weight asymmetry was measured using a hind limb weight bearing apparatus. Bone microarchitecture was characterized using ex vivo μCT. Relative to saline controls, MIA (3.2mg/25μl) produced significant weight asymmetry measured on post-days (PDs) 3, 7, 14, 21 in sedentary rats. Seven days of prior running failed to alter MIA-induced weight asymmetry. In contrast, 21days of prior running resulted in complete reversal of MIA-induced weight asymmetry on all days tested. As a comparator, the opioid agonist morphine (3.2-10mg/kg) dose-dependently reversed weight asymmetry on PDs 3, 7, 14, but was ineffective in later-stage (PD 21) OA. In runners, Cohen's d (effect sizes) for OA vs. controls indicated large increases in bone volume fraction, trabecular number, trabecular thickness, and connective density in lateral compartment, and large decreases in the same parameters in medial compartment. In contrast, effect sizes were small to moderate for sedentary OA vs. Results indicate that voluntary exercise may protect against OA pain, the effect varies as a function of prior exercise duration, and is associated with distinct trabecular bone modifications. Copyright © 2017 Elsevier Inc. All rights reserved.

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.

PubMed

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

2017-10-01

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

Prediction of low bone mass using a combinational approach of cortical and trabecular bone measures from dental panoramic radiographs.

PubMed

Kathirvelu, D; Anburajan, M

2014-09-01

The aim of this study is to extract cortical and trabecular features of the mandible and to develop a novel combinational model of mandibular cortical thickness, trabecular bone area and age in order to predict low bone mineral density or osteoporosis from a dental panoramic radiograph. The study involved 64 south Indian women (age = 52.5 ± 12.7 years) categorised into two groups (normal and low bone mineral density) based on total femur bone mineral density. The dental panoramic radiographs were obtained by a digital scanner, and measurement of total bone mineral density at the right femur was performed by a dual-energy X-ray absorptiometry scanner. The mandibular cortical thickness and panoramic mandibular index were measured bilaterally, and the mean values were considered. The region of interest of 128 × 128 pixels around the mental foramen region was manually cropped and subjected to pre-processing, normalisation and average threshold-based segmentation to determine trabecular bone area. Multiple linear regression analyses of cortical and trabecular measures along with age were performed to develop a combinational model to classify subjects as normal and low bone mineral density. The proposed approach demonstrated strong correlation (r = 0.76; p < 0.01) against the total bone mineral density and resulted in accuracy, sensitivity and positive predictive values of 0.84, 0.92 and 0.85, respectively; the receiver operating characteristic outcomes disclosed that the area under the curve was 0.89.Our results suggest that the proposed combinational model could be useful to diagnose subjects with low bone mineral density. © IMechE 2014.

The effects of cortical bone thickness and trabecular bone strength on noninvasive measures of the implant primary stability using synthetic bone models.

PubMed

Hsu, Jui-Ting; Fuh, Lih-Jyh; Tu, Ming-Gene; Li, Yu-Fen; Chen, Kuan-Ting; Huang, Heng-Li

2013-04-01

This study investigated how the primary stability of a dental implant as measured by the insertion torque value (ITV), Periotest value (PTV), and implant stability quotient (ISQ) is affected by varying thicknesses of cortical bone and strengths of trabecular bone using synthetic bone models. Four synthetic cortical shells (with thicknesses of 0, 1, 2, and 3 mm) were attached to four cellular rigid polyurethane foams (with elastic moduli of 137, 47.5, 23, and 12.4 MPa) and one open-cell rigid polyurethane foam which mimic the osteoporotic bone (with an elastic modulus 6.5 MPa), to represent the jawbones with various cortical bone thicknesses and strengths of trabecular bone. A total of 60 bone specimens accompanied with implants was examined by a torque meter, Osstell resonance frequency analyzer, and Periotest electronic device. All data were statistically analyzed by two-way analysis of variance. In addition, second-order nonlinear regression was utilized to assess the correlations of the primary implant stability with the four cortex thicknesses and five strengths of trabecular bone. ITV, ISQ, and PTV differed significantly (p < .05) and were strongly correlated with the thickness of cortical bone (R(2) > 0.9) and the elastic modulus of trabecular bone (R(2) = 0.74-0.99). The initial stability at the time of implant placement is influenced by both the cortical bone thickness and the strength of trabecular bone; however, these factors are mostly nonlinearly correlated with ITV, PTV, and ISQ. Using ITV and PTV seems more suitable for identifying the primary implant stability in osteoporotic bone with a thin cortex. © 2011 Wiley Periodicals, Inc.

The Lyme Disease Pathogen Borrelia burgdorferi Infects Murine Bone and Induces Trabecular Bone Loss.

PubMed

Tang, Tian Tian; Zhang, Lucia; Bansal, Anil; Grynpas, Marc; Moriarty, Tara J

2017-02-01

Lyme disease is caused by members of the Borrelia burgdorferi sensu lato species complex. Arthritis is a well-known late-stage pathology of Lyme disease, but the effects of B. burgdorferi infection on bone at sites other than articular surfaces are largely unknown. In this study, we investigated whether B. burgdorferi infection affects bone health in mice. In mice inoculated with B. burgdorferi or vehicle (mock infection), we measured the presence of B. burgdorferi DNA in bones, bone mineral density (BMD), bone formation rates, biomechanical properties, cellular composition, and two- and three-dimensional features of bone microarchitecture. B. burgdorferi DNA was detected in bone. In the long bones, increasing B. burgdorferi DNA copy number correlated with reductions in areal and trabecular volumetric BMDs. Trabecular regions of femora exhibited significant, copy number-correlated microarchitectural disruption, but BMD, microarchitectural, and biomechanical properties of cortical bone were not affected. Bone loss in tibiae was not due to increased osteoclast numbers or bone-resorbing surface area, but it was associated with reduced osteoblast numbers, implying that bone loss in long bones was due to impaired bone building. Osteoid-producing and mineralization activities of existing osteoblasts were unaffected by infection. Therefore, deterioration of trabecular bone was not dependent on inhibition of osteoblast function but was more likely caused by blockade of osteoblastogenesis, reduced osteoblast survival, and/or induction of osteoblast death. Together, these data represent the first evidence that B. burgdorferi infection induces bone loss in mice and suggest that this phenotype results from inhibition of bone building rather than increased bone resorption. Copyright © 2017 Tang et al.

Three-dimensional Characterization of Resorption Cavity Size and Location in Human Vertebral Trabecular Bone

PubMed Central

Goff, M.G.; Slyfield, C.R.; Kummari, S.R.; Tkachenko, E.V.; Fischer, S. E.; Yi, Y.H.; Jekir, M.; Keaveny, T.M.; Hernandez, C.J.

2012-01-01

The number and size of resorption cavities in cancellous bone are believed to influence rates of bone loss, local tissue stress and strain and potentially whole bone strength. Traditional two-dimensional approaches to measuring resorption cavities in cancellous bone report the percent of the bone surface covered by cavities or osteoclasts, but cannot measure cavity number or size. Here we use three-dimensional imaging (voxel size 0.7 × 0.7 × 5.0 μm) to characterize resorption cavity location, number and size in human vertebral cancellous bone from nine elderly donors (7 male, 2 female, ages 47–80 years). Cavities were 30.10 ± 8.56 μm in maximum depth, 80.60 ± 22.23 *103 μm2 in surface area and 614.16 ± 311.93 *103 μm3 in volume (mean ± SD). The average number of cavities per unit tissue volume (N.Cv/TV) was 1.25 ± 0.77 mm−3. The ratio of maximum cavity depth to local trabecular thickness was 30.46 ± 7.03 % and maximum cavity depth was greater on thicker trabeculae (p < 0.05, r2 = 0.14). Half of the resorption cavities were located entirely on nodes (the intersection of two or more trabeculae) within the trabecular structure. Cavities that were not entirely on nodes were predominately on plate-like trabeculae oriented in the cranial-caudal (longitudinal) direction. Cavities on plate-like trabeculae were larger in maximum cavity depth, cavity surface area and cavity volume than cavities on rod-like trabeculae (p < 0.05). We conclude from these findings that cavity size and location are related to local trabecular microarchitecture. PMID:22507299

Heritability of Lumbar Trabecular Bone Mechanical Properties in Baboons

PubMed Central

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

2010-01-01

Genetic effects on mechanical properties have been demonstrated in rodents, but not confirmed in primates. Our aim was to quantify the proportion of variation in vertebral trabecular bone mechanical properties that is due to the effects of genes. L3 vertebrae were collected from 110 females and 46 male baboons (6–32 years old) from a single extended pedigree. Cranio-caudally oriented trabecular bone cores were scanned with microCT then tested in monotonic compression to determine apparent ultimate stress, modulus, and toughness. Age and sex effects and heritability (h2) were assessed using maximum likelihood-based variance components methods. Additive effects of genes on residual trait variance were significant for ultimate stress (h2=0.58), toughness (h2=0.64), and BV/TV (h2=0.55). When BV/TV was accounted for, the residual variance in ultimate stress accounted for by the additive effects of genes was no longer significant. Toughness, however, showed evidence of a non-BV/TV-related genetic effect. Overall, maximum stress and modulus show strong genetic effects that are nearly entirely due to bone volume. Toughness shows strong genetic effects related to bone volume and shows additional genetic effects (accounting for 10% of the total trait variance) that are independent of bone volume. These results support continued use of bone volume as a focal trait to identify genes related to skeletal fragility, but also show that other focal traits related to toughness and variation in the organic component of bone matrix will enhance our ability to find additional genes that are particularly relevant to fatigue-related fractures. PMID:19900599

A hyperboliod representation of the bone-marrow interface within 3D NMR images of trabecular bone: applications to skeletal dosimetry

NASA Astrophysics Data System (ADS)

Rajon, D. A.; Shah, A. P.; Watchman, C. J.; Brindle, J. M.; Bolch, W. E.

2003-06-01

Recent advances in physical models of skeletal dosimetry utilize high-resolution NMR microscopy images of trabecular bone. These images are coupled to radiation transport codes to assess energy deposition within active bone marrow irradiated by bone- or marrow-incorporated radionuclides. Recent studies have demonstrated that the rectangular shape of image voxels is responsible for cross-region (bone-to-marrow) absorbed fraction errors of up to 50% for very low-energy electrons (<50 keV). In this study, a new hyperboloid adaptation of the marching cube (MC) image-visualization algorithm is implemented within 3D digital images of trabecular bone to better define the bone-marrow interface, and thus reduce voxel effects in the assessment of cross-region absorbed fractions. To test the method, a mathematical sample of trabecular bone was constructed, composed of a random distribution of spherical marrow cavities, and subsequently coupled to the EGSnrc radiation code to generate reference values for the energy deposition in marrow or bone. Next, digital images of the bone model were constructed over a range of simulated image resolutions, and coupled to EGSnrc using the hyperboloid MC (HMC) algorithm. For the radionuclides 33P, 117mSn, 131I and 153Sm, values of S(marrow←bone) estimated using voxel models of trabecular bone were shown to have relative errors of 10%, 9%, <1% and <1% at a voxel size of 150 µm. At a voxel size of 60 µm, these errors were 6%, 5%, <1% and <1%, respectively. When the HMC model was applied during particle transport, the relative errors on S(marrow←bone) for these same radionuclides were reduced to 7%, 6%, <1% and <1% at a voxel size of 150 µm, and to 2%, 2%, <1% and <1% at a voxel size of 60 µm. The technique was also applied to a real NMR image of human trabecular bone with a similar demonstration of reductions in dosimetry errors.

Serial analysis of gene expression (SAGE) in normal human trabecular meshwork.

PubMed

Liu, Yutao; Munro, Drew; Layfield, David; Dellinger, Andrew; Walter, Jeffrey; Peterson, Katherine; Rickman, Catherine Bowes; Allingham, R Rand; Hauser, Michael A

2011-04-08

To identify the genes expressed in normal human trabecular meshwork tissue, a tissue critical to the pathogenesis of glaucoma. Total RNA was extracted from human trabecular meshwork (HTM) harvested from 3 different donors. Extracted RNA was used to synthesize individual SAGE (serial analysis of gene expression) libraries using the I-SAGE Long kit from Invitrogen. Libraries were analyzed using SAGE 2000 software to extract the 17 base pair sequence tags. The extracted sequence tags were mapped to the genome using SAGE Genie map. A total of 298,834 SAGE tags were identified from all HTM libraries (96,842, 88,126, and 113,866 tags, respectively). Collectively, there were 107,325 unique tags. There were 10,329 unique tags with a minimum of 2 counts from a single library. These tags were mapped to known unique Unigene clusters. Approximately 29% of the tags (orphan tags) did not map to a known Unigene cluster. Thirteen percent of the tags mapped to at least 2 Unigene clusters. Sequence tags from many glaucoma-related genes, including myocilin, optineurin, and WD repeat domain 36, were identified. This is the first time SAGE analysis has been used to characterize the gene expression profile in normal HTM. SAGE analysis provides an unbiased sampling of gene expression of the target tissue. These data will provide new and valuable information to improve understanding of the biology of human aqueous outflow.

Histomorphometric Parameters of the Growth Plate and Trabecular Bone in Wild-Type and Trefoil Factor Family 3 (Tff3)-Deficient Mice Analyzed by Free and Open-Source Image Processing Software.

PubMed

Bijelić, Nikola; Belovari, Tatjana; Stolnik, Dunja; Lovrić, Ivana; Baus Lončar, Mirela

2017-08-01

Trefoil factor family 3 (Tff3) peptide is present during intrauterine endochondral ossification in mice, and its deficiency affects cancellous bone quality in secondary ossification centers of mouse tibiae. The aim of this study was to quantitatively analyze parameters describing the growth plate and primary ossification centers in tibiae of 1-month-old wild-type and Tff3 knock-out mice (n=5 per genotype) by using free and open-source software. Digital photographs of the growth plates and trabecular bone were processed by open-source computer programs GIMP and FIJI. Histomorphometric parameters were calculated using measurements made with FIJI. Tff3 knock-out mice had significantly smaller trabecular number and significantly larger trabecular separation. Trabecular bone volume, trabecular bone surface, and trabecular thickness showed no significant difference between the two groups. Although such histomorphological differences were found in the cancellous bone structure, no significant differences were found in the epiphyseal plate histomorphology. Tff3 peptide probably has an effect on the formation and quality of the cancellous bone in the primary ossification centers, but not through disrupting the epiphyseal plate morphology. This work emphasizes the benefits of using free and open-source programs for morphological studies in life sciences.

Validation of a measuring technique with computed tomography for cement penetration into trabecular bone underneath the tibial tray in total knee arthroplasty on a cadaver model

PubMed Central

2014-01-01

Background In total knee arthroplasty (TKA), cement penetration between 3 and 5 mm beneath the tibial tray is required to prevent loosening of the tibia component. The objective of this study was to develop and validate a reliable in vivo measuring technique using CT imaging to assess cement distribution and penetration depth in the total area underneath a tibia prosthesis. Methods We defined the radiodensity ranges for trabecular tibia bone, polymethylmethacrylate (PMMA) cement and cement-penetrated trabecular bone and measured the percentages of cement penetration at various depths after cementing two tibia prostheses onto redundant femoral heads. One prosthesis was subsequently removed to examine the influence of the metal tibia prostheses on the quality of the CT images. The percentages of cement penetration in the CT slices were compared with percentages measured with photographs of the corresponding transversal slices. Results Trabecular bone and cement-penetrated trabecular bone had no overlap in quantitative scale of radio-density. There was no significant difference in mean HU values when measuring with or without the tibia prosthesis. The percentages of measured cement-penetrated trabecular bone in the CT slices of the specimen were within the range of percentages that could be expected based on the measurements with the photographs (p = 0.04). Conclusions CT scan images provide valid results in measuring the penetration and distribution of cement into trabecular bone underneath the tibia component of a TKA. Since the proposed method does not turn metal elements into artefacts, it enables clinicians to assess the width and density of the cement mantle in vivo and to compare the results of different cementing methods in TKA. PMID:25158996

Assessing vertebral fracture risk on volumetric quantitative computed tomography by geometric characterization of trabecular bone structure

NASA Astrophysics Data System (ADS)

Checefsky, Walter A.; Abidin, Anas Z.; Nagarajan, Mahesh B.; Bauer, Jan S.; Baum, Thomas; Wismüller, Axel

2016-03-01

The current clinical standard for measuring Bone Mineral Density (BMD) is dual X-ray absorptiometry, however more recently BMD derived from volumetric quantitative computed tomography has been shown to demonstrate a high association with spinal fracture susceptibility. In this study, we propose a method of fracture risk assessment using structural properties of trabecular bone in spinal vertebrae. Experimental data was acquired via axial multi-detector CT (MDCT) from 12 spinal vertebrae specimens using a whole-body 256-row CT scanner with a dedicated calibration phantom. Common image processing methods were used to annotate the trabecular compartment in the vertebral slices creating a circular region of interest (ROI) that excluded cortical bone for each slice. The pixels inside the ROI were converted to values indicative of BMD. High dimensional geometrical features were derived using the scaling index method (SIM) at different radii and scaling factors (SF). The mean BMD values within the ROI were then extracted and used in conjunction with a support vector machine to predict the failure load of the specimens. Prediction performance was measured using the root-mean-square error (RMSE) metric and determined that SIM combined with mean BMD features (RMSE = 0.82 +/- 0.37) outperformed MDCT-measured mean BMD (RMSE = 1.11 +/- 0.33) (p < 10-4). These results demonstrate that biomechanical strength prediction in vertebrae can be significantly improved through the use of SIM-derived texture features from trabecular bone.

Use of MR-based trabecular bone microstructure analysis at the distal radius for osteoporosis diagnostics: a study in post-menopausal women with breast cancer and treated with aromatase inhibitor.

PubMed

Baum, Thomas; Karampinos, Dimitrios C; Seifert-Klauss, Vanadin; Pencheva, Tsvetelina D; Jungmann, Pia M; Rummeny, Ernst J; Müller, Dirk; Bauer, Jan S

2016-01-01

Treatment with aromatase inhibitor (AI) is recommended for post-menopausal women with hormone-receptor positive breast cancer. However, AI therapy is known to induce bone loss leading to osteoporosis with an increased risk for fragility fractures. The purpose of this study was to investigate whether changes of magnetic resonance (MR)-based trabecular bone microstructure parameters as advanced imaging biomarker can already be detected in subjects with AI intake but still without evidence for osteoporosis according to dual energy X-ray absorptiometry (DXA)-based bone mineral density (BMD) measurements as current clinical gold standard. Twenty-one postmenopausal women (62±6 years of age) with hormone-receptor positive breast cancer, ongoing treatment with aromatase inhibitor for 23±15 months, and no evidence for osteoporosis (current DXA T-score greater than -2.5) were recruited for this study. Eight young, healthy women (24±2 years of age) were included as controls. All subjects underwent 3 Tesla magnetic resonance imaging (MRI) of the distal radius to assess the trabecular bone microstructure. Trabecular bone microstructure parameters were not significantly (p>0.05) different between subjects with AI intake and controls, including apparent bone fraction (0.42±0.03 vs. 0.42±0.05), trabecular number (1.95±0.10 mm(-1) vs 1.89±0.15 mm(-1)), trabecular separation (0.30±0.03 mm vs 0.31±0.06 mm), trabecular thickness (0.21±0.01 mm vs 0.22±0.02 mm), and fractal dimension (1.70±0.02 vs. 1.70±0.03). These findings suggest that the initial deterioration of trabecular bone microstructure as measured by MRI and BMD loss as measured by DXA occur not sequentially but rather simultaneously. Thus, the use of MR-based trabecular bone microstructure assessment is limited as early diagnostic biomarker in this clinical setting.

Renin inhibitor aliskiren exerts beneficial effect on trabecular bone by regulating skeletal renin-angiotensin system and kallikrein-kinin system in ovariectomized mice.

PubMed

Zhang, Y; Wang, L; Song, Y; Zhao, X; Wong, M S; Zhang, W

2016-03-01

The skeletal renin-angiotensin system contributes to the development of osteoporosis. The renin inhibitor aliskiren exhibited beneficial effects on trabecular bone of osteoporotic mice, and this action might be mediated through angiotensin and bradykinin receptor pathways. This study implies the potential application of renin inhibitor in the management for postmenopausal osteoporosis. The skeletal renin-angiotensin system plays key role in the pathological process of osteoporosis. The present study is designed to elucidate the effect of renin inhibitor aliskiren on trabecular bone and its potential action mechanism in ovariectomized (OVX) mice. The OVX mice were treated with low dose (5 mg/kg) or high dose (25 mg/kg) of aliskiren or its vehicle for 8 weeks. The bone turnover markers were measured by ELISA. The structural parameters of trabecular bone at lumbar vertebra (LV) and distal femoral metaphysis were measured by micro-CT. The expression of messenger RNA (mRNA) and protein was studied by RT-PCR and immunoblotting, respectively. Aliskiren treatment reduced urinary excretion of calcium and serum level of tartrate-resistant acid phosphatase in OVX mice. The treatment with aliskiren significantly increased bone volume (BV/TV) and connectivity density (Conn.D) of trabecular bone at LV-2 and LV-5 as well as dramatically enhanced BV/TV, Conn.D, bone mineral density (BMD/BV) and decreased bone surface (BS/BV) at the distal femoral end. Aliskiren significantly down-regulated the expression of angiotensinogen, angiotensin II (Ang II), Ang II type 1 receptor, bradykinin receptor (BR)-1, and osteocytic-specific gene sclerostin as well as the osteoclast-specific genes, including carbonic anhydrase II, matrix metalloproteinase-9, and cathepsin K. This study revealed that renin inhibitor aliskiren exhibited the beneficial effects on trabecular bone of ovariectomy-induced osteoporotic mice, and the underlying mechanism for this action might be mediated through Ang II and

Lower Trabecular Volumetric BMD at Metaphyseal Regions of Weight-Bearing Bones is Associated With Prior Fracture in Young Girls

PubMed Central

Farr, Joshua N; Tomás, Rita; Chen, Zhao; Lisse, Jeffrey R; Lohman, Timothy G; Going, Scott B

2011-01-01

Understanding the etiology of skeletal fragility during growth is critical for the development of treatments and prevention strategies aimed at reducing the burden of childhood fractures. Thus we evaluated the relationship between prior fracture and bone parameters in young girls. Data from 465 girls aged 8 to 13 years from the Jump-In: Building Better Bones study were analyzed. Bone parameters were assessed at metaphyseal and diaphyseal sites of the nondominant femur and tibia using peripheral quantitative computed tomography (pQCT). Dual-energy X-ray absorptiometry (DXA) was used to assess femur, tibia, lumbar spine, and total body less head bone mineral content. Binary logistic regression was used to evaluate the relationship between prior fracture and bone parameters, controlling for maturity, body mass, leg length, ethnicity, and physical activity. Associations between prior fracture and all DXA and pQCT bone parameters at diaphyseal sites were nonsignificant. In contrast, lower trabecular volumetric BMD (vBMD) at distal metaphyseal sites of the femur and tibia was significantly associated with prior fracture. After adjustment for covariates, every SD decrease in trabecular vBMD at metaphyseal sites of the distal femur and tibia was associated with 1.4 (1.1–1.9) and 1.3 (1.0–1.7) times higher fracture prevalence, respectively. Prior fracture was not associated with metaphyseal bone size (ie, periosteal circumference). In conclusion, fractures in girls are associated with lower trabecular vBMD, but not bone size, at metaphyseal sites of the femur and tibia. Lower trabecular vBMD at metaphyseal sites of long bones may be an early marker of skeletal fragility in girls. © 2011 American Society for Bone and Mineral Research. PMID:20721933

Lower trabecular volumetric BMD at metaphyseal regions of weight-bearing bones is associated with prior fracture in young girls.

PubMed

Farr, Joshua N; Tomás, Rita; Chen, Zhao; Lisse, Jeffrey R; Lohman, Timothy G; Going, Scott B

2011-02-01

Understanding the etiology of skeletal fragility during growth is critical for the development of treatments and prevention strategies aimed at reducing the burden of childhood fractures. Thus we evaluated the relationship between prior fracture and bone parameters in young girls. Data from 465 girls aged 8 to 13 years from the Jump-In: Building Better Bones study were analyzed. Bone parameters were assessed at metaphyseal and diaphyseal sites of the nondominant femur and tibia using peripheral quantitative computed tomography (pQCT). Dual-energy X-ray absorptiometry (DXA) was used to assess femur, tibia, lumbar spine, and total body less head bone mineral content. Binary logistic regression was used to evaluate the relationship between prior fracture and bone parameters, controlling for maturity, body mass, leg length, ethnicity, and physical activity. Associations between prior fracture and all DXA and pQCT bone parameters at diaphyseal sites were nonsignificant. In contrast, lower trabecular volumetric BMD (vBMD) at distal metaphyseal sites of the femur and tibia was significantly associated with prior fracture. After adjustment for covariates, every SD decrease in trabecular vBMD at metaphyseal sites of the distal femur and tibia was associated with 1.4 (1.1-1.9) and 1.3 (1.0-1.7) times higher fracture prevalence, respectively. Prior fracture was not associated with metaphyseal bone size (ie, periosteal circumference). In conclusion, fractures in girls are associated with lower trabecular vBMD, but not bone size, at metaphyseal sites of the femur and tibia. Lower trabecular vBMD at metaphyseal sites of long bones may be an early marker of skeletal fragility in girls. Copyright © 2011 American Society for Bone and Mineral Research.

Trabecular trajectory in the articular processes of the human fourth cervical vertebra

PubMed Central

HERRERA, M.; PANCHÓN, A.; PEREZ-BACETE, M.

2001-01-01

The articular processes (AP) of the neural arch have been implicated in weight transmission through the cervical spine. To analyse the mechanism of weight transmission in the AP, we studied the direction of forces within it, in particular, the pattern of trabecular trajectories. Twenty-two AP from C4 vertebrae were studied in anatomical sections, and corresponding photoelastic models from selected sections were constructed and analysed. Anatomical and photoelastic findings show the subarticular spongiosa of the superior articular process (SAP) to be orthogonally arranged with vertical and oblique trabeculae in the direction of compressive forces and additional trabeculae always oriented perpendicular to the former. Vertical and oblique trabeculae are divided into rostral, middle and posterior groups. Rostral and middle trabeculae end in the anterior wall of the SAP and the transitional zone with the pedicle. Posterior trabeculae end in the subarticular spongiosa of the inferior articular process (IAP). The findings relating to trabecular trajectories in the SAP differ from previous descriptions and instead suggest that a part of the weight forces distributed within the AP transmit to the subchondral zone of the IAP. Knowledge of the trajectorial architecture of the AP may contribute to refining finite element analytical models for investigating its weight-bearing function. PMID:11554512

The Role of Trabecular Microarchitecture in the Formation, Accumulation, and Morphology of Microdamage in Human Cancellous Bone

PubMed Central

Karim, Lamya; Vashishth, Deepak

2011-01-01

Alterations in microdamage morphology and accumulation are typically attributed to impaired remodeling, but may also result from changes in microdamage initiation and propagation. Such alterations are relevant for cancellous bone with high metabolic activity and numerous bone quality changes. This study investigates the role of trabecular microarchitecture on morphology and accumulation of microdamage in human cancellous bone. Trabecular bone cores from donors of varying ages and bone volume fraction (BV/TV) were separated into high and low BV/TV groups. Samples were subjected to no load or uniaxial compression to 0.6% (pre-yield) or 1.1% (post-yield) strain. Microdamage was stained with lead uranyl acetate and specimens were imaged via microcomputed tomography to quantify microdamage and determine its morphology in three-dimensions (3D). Donors with high BV/TV had greater post yield strain and were tougher than low BV/TV donors. High BV/TV bone had less microdamage than low BV/TV bone under post- but not pre-yield loading. Microdamage under both loading conditions showed significant correlations with microarchitecture and BV/TV, but the key predictor was structure model index (SMI). As SMI increased (more trabecular rods), microdamage morphology became crack-like. Thus, low BV/TV and increased SMI have strong influences on microdamage accumulation in bone through altered initiation. PMID:21538510

Influence of the cutting edge angle of a titanium instrument on chip formation in the machining of trabecular and cortical bone.

PubMed

von See, Constantin; Stoetzer, Marcus; Ruecker, Martin; Wagner, Max; Schumann, Paul; Gellrich, Nils-Claudius

2014-01-01

The placement of self-tapping implants is associated with microfractures and the formation of bone chips along the cutting flutes. This study was conducted to investigate the effect of different cutting edge angles on chip formation during the machining of trabecular and cortical bone using instruments with a rough titanium surface. Mandibular cortical and trabecular bone specimens were obtained from freshly slaughtered domestic pigs. A predefined thrust force was applied to the specimens. Four specially designed cutting instruments that simulated dental implants and had a rough titanium surface were allowed to complete one full revolution at cutting edge angles of 55, 65, 75, and 85 degrees, respectively. Torque and thrust were measured during the cutting process. Bone chips were measured and weighed under a microscope. Different cutting edge angles did not lead to significant differences in torque. The lowest torque values were measured when the cutting edges were positioned at 65 degrees in trabecular bone and at 85 degrees in cortical bone. Bone chips were significantly larger and heavier at angles of 55 and 65 degrees than at angles of 75 and 85 degrees in trabecular bone. Instruments with a rough titanium surface show considerable angle-dependent differences in chip formation. In addition to bone density, the angle of the cutting edges should be taken into consideration during the placement of dental implants. Good results were obtained when the cutting edges were positioned at an angle of 65 degrees. This angle can have positive effects on osseointegration.

Assessment of vertebral microarchitecture in overt and mild Cushing's syndrome using trabecular bone score.

PubMed

Vinolas, Helene; Grouthier, Virginie; Mehsen-Cetre, Nadia; Boisson, Amandine; Winzenrieth, Renaud; Schaeverbeke, Thierry; Mesguich, Charles; Bordenave, Laurence; Tabarin, Antoine

2018-05-21

Osteoporotic fractures associated with Cushing's syndrome (CS) may occur despite normal bone mineral density (BMD). Few studies have described alterations in vertebral microarchitecture in glucocorticoid-treated patients and during CS. Trabecular bone score (TBS) estimates trabecular microarchitecture from dual-energy X-ray absorptiometry acquisitions. Our aim was to compare vertebral BMD and TBS in patients with overt CS and mild autonomous cortisol secretion (MACE), and following cure of overt CS. University Hospital. Monocentric retrospective cross-sectional and longitudinal studies of consecutive patients. A total of 110 patients were studied: 53 patients had CS (35, 11 and 7 patients with Cushing's disease, bilateral macronodular adrenal hyperplasia and ectopic ACTH secretion respectively); 39 patients had MACE (10 patients with a late post-operative recurrence of Cushing's disease and 29 patients with adrenal incidentalomas); 18 patients with non-secreting adrenal incidentalomas. 14 patients with overt CS were followed for up to 2 years after cure. Vertebral osteoporosis at BMD and degraded microarchitecture at TBS were found in 24% and 43% of patients with CS, respectively (P < .03). As compared to patients with nonsecreting incidentalomas, patients with MACE had significantly decreased TBS (P < .04) but not BMD. Overt fragility fractures tended to be associated with low TBS (P = .07) but not with low BMD. TBS, but not BMD values, decreased with the intensity of hypercortisolism independently of its aetiology (P < .01). Following remission of CS, TBS improved more markedly and rapidly than BMD (10% vs 3%, respectively; P < .02). Trabecular bone score may be a promising, noninvasive, widely available and inexpensive complementary tool for the routine assessment of the impact of CS and MACE on bone in clinical practice. © 2018 John Wiley & Sons Ltd.

Local plate/rod descriptors of 3D trabecular bone micro-CT images from medial axis topologic analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peyrin, Francoise; Attali, Dominique; Chappard, Christine

Purpose: Trabecular bone microarchitecture is made of a complex network of plate and rod structures evolving with age and disease. The purpose of this article is to propose a new 3D local analysis method for the quantitative assessment of parameters related to the geometry of trabecular bone microarchitecture. Methods: The method is based on the topologic classification of the medial axis of the 3D image into branches, rods, and plates. Thanks to the reversibility of the medial axis, the classification is next extended to the whole 3D image. Finally, the percentages of rods and plates as well as their meanmore » thicknesses are calculated. The method was applied both to simulated test images and 3D micro-CT images of human trabecular bone. Results: The classification of simulated phantoms made of plates and rods shows that the maximum error in the quantitative percentages of plate and rods is less than 6% and smaller than with the structure model index (SMI). Micro-CT images of human femoral bone taken in osteoporosis and early or advanced osteoarthritis were analyzed. Despite the large physiological variability, the present method avoids the underestimation of rods observed with other local methods. The relative percentages of rods and plates were not significantly different between osteoarthritis and osteoporotic groups, whereas their absolute percentages were in relation to an increase of rod and plate thicknesses in advanced osteoarthritis with also higher relative and absolute number of nodes. Conclusions: The proposed method is model-independent, robust to surface irregularities, and enables geometrical characterization of not only skeletal structures but entire 3D images. Its application provided more accurate results than the standard SMI on simple simulated phantoms, but the discrepancy observed on the advanced osteoarthritis group raises questions that will require further investigations. The systematic use of such a local method in the characterization

Ab interno trabecular bypass surgery with iStent for open angle glaucoma

PubMed Central

Le, Jimmy T; Bicket, Amanda K; Li, Tianjing

2018-01-01

This is a protocol for a Cochrane Review (Intervention). The objectives are as follows: The primary objective is to assess the comparative effectiveness and safety of ab interno trabecular bypass surgery with iStent or iStent inject for OAG in comparison to conventional medical, laser, or surgical treatment. A secondary objective is to examine the effectiveness and safety of iStent or iStent Inject surgery in people who have concomitant phacoemulsification. PMID:27526051

Bonding strength of glass-ceramic trabecular-like coatings to ceramic substrates for prosthetic applications.

PubMed

Chen, Qiang; Baino, Francesco; Pugno, Nicola M; Vitale-Brovarone, Chiara

2013-04-01

A new approach based on the concepts of quantized fracture mechanics (QFM) is presented and discussed in this paper to estimate the bonding strength of trabecular-like coatings, i.e. glass-ceramic scaffolds mimicking the architecture of cancellous bone, to ceramic substrates. The innovative application of glass-derived scaffolds as trabecular-like coatings is proposed in order to enhance the osteointegration of prosthetic ceramic devices. The scaffolds, prepared by polymeric sponge replication, are joined to alumina substrates by a dense glass-ceramic coating (interlayer) and the so-obtained 3-layer constructs are investigated from micro-structural, morphological and mechanical viewpoints. In particular, the fracture strengths of three different crack propagation modes, i.e. glass-derived scaffold fracture, interface delamination or mixed fracture, are predicted in agreement with those of experimental mechanical tests. The approach proposed in this work could have interesting applications towards an ever more rational design of bone tissue engineering biomaterials and coatings, in view of the optimization of their mechanical properties for making them actually suitable for clinical applications. Copyright © 2012 Elsevier B.V. All rights reserved.

Homocysteine induces oxidative stress to damage trabecular meshwork cells.

PubMed

You, Zhi-Peng; Zhang, Yue-Zhi; Zhang, Yu-Lan; Shi, Lu; Shi, Ke

2018-05-01

The aim of the present study was to investigate the effect of homocysteine (Hcy) in on human trabecular meshwork cells (HTMCs). A total of 41 patients with primary open-angle glaucoma (POAG) and 53 patients with senile cataracts (control group) were recruited. Plasma and aqueous humor samples were collected and the Hcy concentrations were determined using enzymatic cycling assays. In cell experiments, normal HTMCs were passaged and randomly divided into a blank control group, a normal HTMC group and experimental groups, which were treated with different concentrations of Hcy. The HTMC activities were detected using the Cell Counting Kit-8 method and the HTMC mitochondrial membrane potential (MMP) was detected using JC-1 staining. Reactive oxygen species (ROS) released by trabecular meshwork cells was detected using flow cytometry and superoxide dismjutase-1 (SOD1) expression was detected using immunoblotting. The results revealed that the concentration of Hcy in the plasma and aqueous humor of the POAG group (14.44±0.86 and 1.60±0.27 µmol/l, respectively) was significantly higher compared with the control group (10.82±0.29 and 0.69±0.39 µmol/l). All tested concentrations (30, 100, 300 and 1,000 µmol/l) of Hcy reduced the MMP in HTMCs and inhibited HTMC proliferation in a dose-dependent manner. ROS production by HTMCs significantly increased with increased concentrations of Hcy, whereas SOD1 expression significantly decreased in a dose-dependent manner. In summary, patients with POAG were demonstrated to have increased concentrations of Hcy in the plasma and aqueous humor. High concentrations of Hcy in HTMCs induced an oxidative stress state, thereby further inhibiting HTMC proliferation. The results of the present study demonstrate that Hcy may be a potential treatment target in patients with POAG.

A novel use of 3D printing model demonstrates the effects of deteriorated trabecular bone structure on bone stiffness and strength.

PubMed

Barak, Meir Max; Black, Margaret Arielle

2018-02-01

Trabecular bone structure is crucial to normal mechanical behavior of bones. Studies have shown that osteoporosis negatively affects trabecular bone structure, mainly by reducing bone volume fraction (BV/TV) and thus increasing fracture risk. One major limitation in assessing and quantifying the effect of this structural deterioration is that no two trabecular structures are identical. Thus, when we compare a group of healthy bones against a different group of bones that experienced resorption (i.e. decreased BV/TV) we only discover an "average" mechanical effect. It is impossible to quantify the mechanical effect of individual structural deterioration for each sample, simply because we never have the same sample in both states (intact and deteriorated structure). 3D printing is a new technology that can assist in overcoming this issue. Here we report a preliminary study that compares a healthy 3D printed trabecular bone model with the same model after bone resorption was simulated. Since the deteriorated structural bone model is derived from the healthy one, it is possible to directly estimate (percentage wise) the decrease of tissue stiffness and strength as a result of bone resorption for this specific structure. Our results demonstrate that a relatively small decrease in BV/TV (about 8%) leads to a dramatic decrease in structural strength (24%) and structural stiffness (17%), (P < 0.01). Structural strength decreased from an average of 9.14 ± 2.85MPa to 6.97 ± 2.44MPa, while structural stiffness decreased from an average of 282.5 ± 63.4N/mm to 233.8 ± 51.2N/mm. This study demonstrates that 3D printing is a novel and valuable tool for quantifying the effect of structural deterioration on the mechanical properties of trabecular bone. In the future, this approach may help us attain better personal fracture risk assessments by CT scanning, 3D printing and mechanically testing individual bone replicas from patients suffering excessive bone resorption. Copyright

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

PubMed Central

Aw, Moom Sinn; Khalid, Kamarul A; Gulati, Karan; Atkins, Gerald J; Pivonka, Peter; Findlay, David M; Losic, Dusan

2012-01-01

Purpose The aim of this study was to investigate the application of the three-dimensional bone bioreactor for studying drug-release kinetics and distribution of drugs in the ex vivo cancellous bone environment, and to demonstrate the application of nanoengineered titanium (Ti) wires generated with titania nanotube (TNT) arrays as drug-releasing implants for local drug delivery Methods Nanoengineered Ti wires covered with a layer of TNT arrays implanted in bone were used as a drug-releasing implant. Viable bovine trabecular bone was used as the ex vivo bone substrate embedded with the implants and placed in the bone reactor. A hydrophilic fluorescent dye (rhodamine B) was used as the model drug, loaded inside the TNT–Ti implants, to monitor drug release and transport in trabecular bone. The distribution of released model drug in the bone was monitored throughout the bone structure, and concentration profiles at different vertical (0–5 mm) and horizontal (0–10 mm) distances from the implant surface were obtained at a range of release times from 1 hour to 5 days. Results Scanning electron microscopy confirmed that well-ordered, vertically aligned nanotube arrays were formed on the surface of prepared TNT–Ti wires. Thermogravimetric analysis proved loading of the model drug and fluorescence spectroscopy was used to show drug-release characteristics in-vitro. The drug release from implants inserted into bone ex vivo showed a consistent gradual release of model drug from the TNT–Ti implants, with a characteristic three-dimensional distribution into the surrounding bone, over a period of 5 days. The parameters including the flow rate of bone culture medium, differences in trabecular microarchitecture between bone samples, and mechanical loading were found to have the most significant influence on drug distribution in the bone. Conclusion These results demonstrate the utility of the Zetos™ system for ex vivo drug-release studies in bone, which can be applied to

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

PubMed

Aw, Moom Sinn; Khalid, Kamarul A; Gulati, Karan; Atkins, Gerald J; Pivonka, Peter; Findlay, David M; Losic, Dusan

2012-01-01

The aim of this study was to investigate the application of the three-dimensional bone bioreactor for studying drug-release kinetics and distribution of drugs in the ex vivo cancellous bone environment, and to demonstrate the application of nanoengineered titanium (Ti) wires generated with titania nanotube (TNT) arrays as drug-releasing implants for local drug delivery Nanoengineered Ti wires covered with a layer of TNT arrays implanted in bone were used as a drug-releasing implant. Viable bovine trabecular bone was used as the ex vivo bone substrate embedded with the implants and placed in the bone reactor. A hydrophilic fluorescent dye (rhodamine B) was used as the model drug, loaded inside the TNT-Ti implants, to monitor drug release and transport in trabecular bone. The distribution of released model drug in the bone was monitored throughout the bone structure, and concentration profiles at different vertical (0-5 mm) and horizontal (0-10 mm) distances from the implant surface were obtained at a range of release times from 1 hour to 5 days. Scanning electron microscopy confirmed that well-ordered, vertically aligned nanotube arrays were formed on the surface of prepared TNT-Ti wires. Thermogravimetric analysis proved loading of the model drug and fluorescence spectroscopy was used to show drug-release characteristics in-vitro. The drug release from implants inserted into bone ex vivo showed a consistent gradual release of model drug from the TNT-Ti implants, with a characteristic three-dimensional distribution into the surrounding bone, over a period of 5 days. The parameters including the flow rate of bone culture medium, differences in trabecular microarchitecture between bone samples, and mechanical loading were found to have the most significant influence on drug distribution in the bone. These results demonstrate the utility of the Zetos™ system for ex vivo drug-release studies in bone, which can be applied to optimize the delivery of specific therapies

Relationship between trabecular texture features of CT images and an amount of bone cement volume injection in percutaneous vertebroplasty

NASA Astrophysics Data System (ADS)

Tack, Gye Rae; Choi, Hyung Guen; Shin, Kyu-Chul; Lee, Sung J.

2001-06-01

Percutaneous vertebroplasty is a surgical procedure that was introduced for the treatment of compression fracture of the vertebrae. This procedure includes puncturing vertebrae and filling with polymethylmethacrylate (PMMA). Recent studies have shown that the procedure could provide structural reinforcement for the osteoporotic vertebrae while being minimally invasive and safe with immediate pain relief. However, treatment failures due to disproportionate PMMA volume injection have been reported as one of complications in vertebroplasty. It is believed that control of PMMA volume is one of the most critical factors that can reduce the incidence of complications. In this study, appropriate amount of PMMA volume was assessed based on the imaging data of a given patient under the following hypotheses: (1) a relationship can be drawn between the volume of PMMA injection and textural features of the trabecular bone in preoperative CT images and (2) the volume of PMMA injection can be estimated based on 3D reconstruction of postoperative CT images. Gray-level run length analysis was used to determine the textural features of the trabecular bone. The width of trabecular (T-texture) and the width of intertrabecular spaces (I-texture) were calculated. The correlation between PMMA volume and textural features of patient's CT images was also examined to evaluate the appropriate PMMA amount. Results indicated that there was a strong correlation between the actual PMMA injection volume and the area of the intertrabecular space and that of trabecular bone calculated from the CT image (correlation coefficient, requals0.96 and requals-0.95, respectively). T- texture (requals-0.93) did correlate better with the actual PMMA volume more than the I-texture (requals0.57). Therefore, it was demonstrated that appropriate PMMA injection volume could be predicted based on the textural analysis for better clinical management of the osteoporotic spine.

Trabecular bone strains around a dental implant and associated micromotions--a micro-CT-based three-dimensional finite element study.

PubMed

Limbert, Georges; van Lierde, Carl; Muraru, O Luiza; Walboomers, X Frank; Frank, Milan; Hansson, Stig; Middleton, John; Jaecques, Siegfried

2010-05-07

The first objective of this computational study was to assess the strain magnitude and distribution within the three-dimensional (3D) trabecular bone structure around an osseointegrated dental implant loaded axially. The second objective was to investigate the relative micromotions between the implant and the surrounding bone. The work hypothesis adopted was that these virtual measurements would be a useful indicator of bone adaptation (resorption, homeostasis, formation). In order to reach these objectives, a microCT-based finite element model of an oral implant implanted into a Berkshire pig mandible was developed along with a robust software methodology. The finite element mesh of the 3D trabecular bone architecture was generated from the segmentation of microCT scans. The implant was meshed independently from its CAD file obtained from the manufacturer. The meshes of the implant and the bone sample were registered together in an integrated software environment. A series of non-linear contact finite element (FE) analyses considering an axial load applied to the top of the implant in combination with three sets of mechanical properties for the trabecular bone tissue was devised. Complex strain distribution patterns are reported and discussed. It was found that considering the Young's modulus of the trabecular bone tissue to be 5, 10 and 15GPa resulted in maximum peri-implant bone microstrains of about 3000, 2100 and 1400. These results indicate that, for the three sets of mechanical properties considered, the magnitude of maximum strain lies within an homeostatic range known to be sufficient to maintain/form bone. The corresponding micro-motions of the implant with respect to the bone microstructure were shown to be sufficiently low to prevent fibrous tissue formation and to favour long-term osseointegration. Copyright 2010 Elsevier Ltd. All rights reserved.

Comparison of synchrotron radiation and conventional x-ray microcomputed tomography for assessing trabecular bone microarchitecture of human femoral heads

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chappard, Christine; Basillais, Armelle; Benhamou, Laurent

Microcomputed tomography ({mu}CT) produces three-dimensional (3D) images of trabecular bone. We compared conventional {mu}CT (C{mu}CT) with a polychromatic x-ray cone beam to synchrotron radiation (SR) {mu}CT with a monochromatic parallel beam for assessing trabecular bone microarchitecture of 14 subchondral femoral head specimens from patients with osteoarthritis (n=10) or osteoporosis (n=4). SR{mu}CT images with a voxel size of 10.13 {mu}m were reconstructed from 900 2D radiographic projections (angular step, 0.2 deg. ). C{mu}CT images with a voxel size of 10.77 {mu}m were reconstructed from 205, 413, and 825 projections obtained using angular steps of 0.9 deg., 0.45 deg., and 0.23 deg.,more » respectively. A single threshold was used to binarize the images. We computed bone volume/tissue volume (BV/TV), bone surface/bone volume (BS/BV), trabecular number (Tb.N), trabecular thickness (Tb.Th and Tb.Th*), trabecular spacing (Tb.Sp), degree of anisotropy (DA), and Euler density. With the 0.9 deg. angular step, all C{mu}CT values were significantly different from SR{mu}CT values. With the 0.23 deg. and 0.45 deg. rotation steps, BV/TV, Tb.Th, and BS/BV by C{mu}CT differed significantly from the values by SR{mu}CT. The error due to slice matching (visual site matching {+-}10 slices) was within 1% for most parameters. Compared to SR{mu}CT, BV/TV, Tb.Sp, and Tb.Th by C{mu}CT were underestimated, whereas Tb.N and Tb.Th* were overestimated. A Bland and Altman plot showed no bias for Tb.N or DA. Bias was -0.8{+-}1.0%, +5.0{+-}1.1 {mu}m, -5.9{+-}6.3 {mu}m, and -5.7{+-}29.1 {mu}m for BV/TV, Tb.Th*, Tb.Th, and Tb.Sp, respectively, and the differences did not vary over the range of values. Although systematic differences were noted between SR{mu}CT and C{mu}CT values, correlations between the techniques were high and the differences would probably not change the discrimination between study groups. C{mu}CT provides a reliable 3D assessment of human defatted bone when working

Micro-mechanical damage of trabecular bone-cement interface under selected loading conditions: a finite element study.

PubMed

Zhang, Qing-Hang; Tozzi, Gianluca; Tong, Jie

2014-01-01

In this study, two micro finite element models of trabecular bone-cement interface developed from high resolution computed tomography (CT) images were loaded under compression and validated using the in situ experimental data. The models were then used under tension and shear to examine the load transfer between the bone and cement and the micro damage development at the bone-cement interface. In addition, one models was further modified to investigate the effect of cement penetration on the bone-cement interfacial behaviour. The simulated results show that the load transfer at the bone-cement interface occurred mainly in the bone cement partially interdigitated region, while the fully interdigitated region seemed to contribute little to the mechanical response. Consequently, cement penetration beyond a certain value would seem to be ineffective in improving the mechanical strength of trabecular bone-cement interface. Under tension and shear loading conditions, more cement failures were found in denser bones, while the cement damage is generally low under compression.

Robust segmentation of trabecular bone for in vivo CT imaging using anisotropic diffusion and multi-scale morphological reconstruction

NASA Astrophysics Data System (ADS)

Chen, Cheng; Jin, Dakai; Zhang, Xiaoliu; Levy, Steven M.; Saha, Punam K.

2017-03-01

Osteoporosis is associated with an increased risk of low-trauma fractures. Segmentation of trabecular bone (TB) is essential to assess TB microstructure, which is a key determinant of bone strength and fracture risk. Here, we present a new method for TB segmentation for in vivo CT imaging. The method uses Hessian matrix-guided anisotropic diffusion to improve local separability of trabecular structures, followed by a new multi-scale morphological reconstruction algorithm for TB segmentation. High sensitivity (0.93), specificity (0.93), and accuracy (0.92) were observed for the new method based on regional manual thresholding on in vivo CT images. Mechanical tests have shown that TB segmentation using the new method improved the ability of derived TB spacing measure for predicting actual bone strength (R2=0.83).

Ibandronate

MedlinePlus

... or other problems with your stomach or esophagus (tube that connects the throat to the stomach); cancer; any type of infection, especially in your mouth; problems with your mouth, teeth, or gums; any condition that stops your blood ...

Collagen and collagen-chondroitin sulfate scaffolds with uniaxially aligned pores for the biomimetic, three dimensional culture of trabecular meshwork cells.

PubMed

Osmond, Matthew; Bernier, Sarah M; Pantcheva, Mina B; Krebs, Melissa D

2017-04-01

Glaucoma is a disease in which damage to the optic nerve leads to progressive, irreversible vision loss. The intraocular pressure (IOP) is the only modifiable risk factor for glaucoma and its lowering is considered a useful strategy for preventing or slowing down the progression of glaucomatous neuropathy. Elevated intraocular pressure associated with glaucoma is due to increased aqueous humor outflow resistance, primarily through the trabecular meshwork (TM) of the eye. Current in vitro models of the trabecular meshwork are oversimplified and do not capture the organized and complex three-dimensional nature of this tissue that consists primarily of collagen and glycoasaminoglycans. In this work, collagen and collagen-chondroitin sulfate (CS) scaffolds were fabricated via unidirectional freezing and lyophilization to induce the formation of aligned pores. Scaffolds were characterized by scanning electron microscopy, dynamic mechanical analysis, and a chondroitin sulfate quantification assay. Scaffold characterization confirmed the formation of aligned pores, and also that the CS was leaching out of the scaffolds over time. Primary porcine trabecular meshwork (TM) cells were seeded onto the surface of scaffolds and their gene expression, proliferation, viability, migration into the scaffolds, and morphology were examined. The TM cells were viable and proliferated 2 weeks after seeding. The cells migrated down into the internal scaffold structure and their morphology reflected the topography and alignment of the scaffold structure. This work is a promising step toward the development of a three dimensional in vitro model of the TM that can be used for testing of glaucoma pharmacological agents in future experimentation and to better our understanding of the trabecular meshwork and its complex physiology. Biotechnol. Bioeng. 2017;114: 915-923. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Trabecular meshwork stiffness in glaucoma.

PubMed

Wang, Ke; Read, A Thomas; Sulchek, Todd; Ethier, C Ross

2017-05-01

Alterations in stiffness of the trabecular meshwork (TM) may play an important role in primary open-angle glaucoma (POAG), the second leading cause of blindness. Specifically, certain data suggest an association between elevated intraocular pressure (IOP) and increased TM stiffness; however, the underlying link between TM stiffness and IOP remains unclear and requires further study. We here first review the literature on TM stiffness measurements, encompassing various species and based on a number of measurement techniques, including direct approaches such as atomic force microscopy (AFM) and uniaxial tension tests, and indirect methods based on a beam deflection model. We also briefly review the effects of several factors that affect TM stiffness, including lysophospholipids, rho-kinase inhibitors, cytoskeletal disrupting agents, dexamethasone (DEX), transforming growth factor-β 2 (TGF-β 2 ), nitric oxide (NO) and cellular senescence. We then describe a method we have developed for determining TM stiffness measurement in mice using a cryosection/AFM-based approach, and present preliminary data on TM stiffness in C57BL/6J and CBA/J mouse strains. Finally, we investigate the relationship between TM stiffness and outflow facility between these two strains. The method we have developed shows promise for further direct measurements of mouse TM stiffness, which may be of value in understanding mechanistic relations between outflow facility and TM biomechanical properties. Copyright © 2016 Elsevier Ltd. All rights reserved.

Strain rate dependency of bovine trabecular bone under impact loading at sideways fall velocity.

PubMed

Enns-Bray, William S; Ferguson, Stephen J; Helgason, Benedikt

2018-05-03

There is currently a knowledge gap in scientific literature concerning the strain rate dependent properties of trabecular bone at intermediate strain rates. Meanwhile, strain rates between 10 and 200/s have been observed in previous dynamic finite element models of the proximal femur loaded at realistic sideways fall speeds. This study aimed to quantify the effect of strain rate (ε̇) on modulus of elasticity (E), ultimate stress (σ u ), failure energy (U f ), and minimum stress (σ m ) of trabecular bone in order to improve the biofidelity of material properties used in dynamic simulations of sideways fall loading on the hip. Cylindrical cores of trabecular bone (D = 8 mm, L gauge  = 16 mm, n = 34) from bovine proximal tibiae and distal femurs were scanned in µCT (10 µm), quantifying apparent density (ρ app ) and degree of anisotropy (DA), and subsequently impacted within a miniature drop tower. Force of impact was measured using a piezoelectric load cell (400 kHz), while displacement during compression was measured from high speed video (50,000 frames/s). Four groups, with similar density distributions, were loaded at different impact velocities (0.84, 1.33, 1.75, and 2.16 m/s) with constant kinetic energy (0.4 J) by adjusting the impact mass. The mean strain rates of each group were significantly different (p < 0.05) except for the two fastest impact speeds (p = 0.09). Non-linear regression models correlated strain rate, DA, and ρ app with ultimate stress (R 2  = 0.76), elastic modulus (R 2  = 0.63), failure energy (R 2  = 0.38), and minimum stress (R 2  = 0.57). These results indicate that previous estimates of σ u could be under predicting the mechanical properties at strain rates above 10/s. Copyright © 2018 Elsevier Ltd. All rights reserved.

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

PubMed

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

2011-01-01

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

Ligand-Mediated Activation of an Engineered Gs G Protein-Coupled Receptor in Osteoblasts Increases Trabecular Bone Formation

PubMed Central

Hsiao, Edward C.; Millard, Susan M.; Louie, Alyssa; Huang, Yong; Conklin, Bruce R.; Nissenson, Robert A.

2010-01-01

Age-dependent changes in skeletal growth play important roles in regulating skeletal expansion and in the course of many diseases affecting bone. How G protein-coupled receptor (GPCR) signaling affects these changes is poorly understood. Previously, we described a mouse model expressing Rs1, an engineered receptor with constitutive Gs activity. Rs1 expression in osteoblasts from gestation induced a dramatic age-dependent increase in trabecular bone with features resembling fibrous dysplasia; however, these changes were greatly minimized if Rs1 expression was delayed until after puberty. To further investigate whether ligand-induced activation of the Gs-GPCR pathway affects bone formation in adult mice, we activated Rs1 in adult mice with the synthetic ligand RS67333 delivered continuously via an osmotic pump or intermittently by daily injections. We found that osteoblasts from adult animals can be stimulated to form large amounts of bone, indicating that adult mice are sensitive to the dramatic bone- forming actions of Gs signaling in osteoblasts. In addition, our results show that intermittent and continuous activation of Rs1 led to structurally similar but quantitatively different degrees of trabecular bone formation. These results indicate that activation of a Gs-coupled receptor in osteoblasts of adult animals by either intermittent or continuous ligand administration can increase trabecular bone formation. In addition, osteoblasts located at the bone epiphyses may be more responsive to Gs signaling than osteoblasts at the bone diaphysis. This model provides a powerful tool for investigating the effects of ligand-activated Gs-GPCR signaling on dynamic bone growth and remodeling. PMID:20150184

Deficits in Trabecular Bone Microarchitecture in Young Women With Type 1 Diabetes Mellitus.

PubMed

Abdalrahaman, Naiemh; McComb, Christie; Foster, John E; McLean, John; Lindsay, Robert S; McClure, John; McMillan, Martin; Drummond, Russell; Gordon, Derek; McKay, Gerard A; Shaikh, M Guftar; Perry, Colin G; Ahmed, S Faisal

2015-08-01

The pathophysiological mechanism of increased fractures in young adults with type 1 diabetes mellitus (T1DM) is unclear. We conducted a case-control study of trabecular bone microarchitecture and vertebral marrow adiposity in young women with T1DM. Thirty women with T1DM with a median age (range) age of 22.0 years (16.9, 36.1) attending one outpatient clinic with a median age at diagnosis of 9.7 years (0.46, 14.8) were compared with 28 age-matched healthy women who acted as controls. Measurements included MRI-based assessment of proximal tibial bone volume/total volume (appBV/TV), trabecular separation (appTb.Sp), vertebral bone marrow adiposity (BMA), and abdominal adipose tissue and biochemical markers of GH/IGF-1 axis (IGF-1, IGFBP3, ALS) and bone turnover. Median appBV/TV in cases and controls was 0.3 (0.22, 0.37) and 0.33 (0.26, 0.4), respectively (p = 0.018) and median appTb.Sp in T1DM was 2.59 (2.24, 3.38) and 2.32 (2.03, 2.97), respectively (p = 0.012). The median appBV/TV was 0.28 (0.22, 0.33) in those cases with retinopathy (n = 15) compared with 0.33 (0.25, 0.37) in those without retinopathy (p = 0.02). Although median visceral adipose tissue in cases was higher than in controls at 5733 mm(3) (2030, 11,144) and 3460 mm(3) (1808, 6832), respectively (p = 0.012), there was no difference in median BMA, which was 31.1% (9.9, 59.9) and 26.3% (8.5, 49.8) in cases and controls, respectively (p = 0.2). Serum IGF-1 and ALS were also lower in cases, and the latter showed an inverse association to appTbSp (r = -0.30, p = 0.04). Detailed MRI studies in young women with childhood-onset T1DM have shown clear deficits in trabecular microarchitecture of the tibia. Underlying pathophysiological mechanisms may include a microvasculopathy. © 2015 American Society for Bone and Mineral Research.

Precision of pQCT-measured total, trabecular and cortical bone area, content, density and estimated bone strength in children

PubMed Central

Duff, W.R.D.; Björkman, K.M.; Kawalilak, C.E.; Kehrig, A.M.; Wiebe, S.; Kontulainen, S.

2017-01-01

Objectives: To define pQCT precision errors, least-significant-changes, and identify associated factors for bone outcomes at the radius and tibia in children. Methods: We obtained duplicate radius and tibia pQCT scans from 35 children (8-14yrs). We report root-mean-squared coefficient of variation (CV%RMS) and 95% limits-of-agreement to characterize repeatability across scan quality and least-significant-changes for bone outcomes at distal (total and trabecular area, content and density; and compressive bone strength) and shaft sites (total area and content; cortical area content, density and thickness; and torsional bone strength). We used Spearman’s rho to identify associations between CV% and time between measurements, child’s age or anthropometrics. Results: After excluding unanalyzable scans (6-10% of scans per bone site), CV%RMS ranged from 4% (total density) to 19% (trabecular content) at the distal radius, 4% (cortical content) to 8% (cortical thickness) at the radius shaft, 2% (total density) to 14% (trabecular content) at the distal tibia and from 2% (cortical content) to 6% (bone strength) at the tibia shaft. Precision errors were within 95% limits-of-agreement across scan quality. Age was associated (rho -0.4 to -0.5, p <0.05) with CV% at the tibia. Conclusion: Bone density outcomes and cortical bone properties appeared most precise (CV%RMS <5%) in children. PMID:28574412

Trabecular bone microstructure is impaired in the proximal femur of human immunodeficiency virus-infected men with normal bone mineral density.

PubMed

Kazakia, Galateia J; Carballido-Gamio, Julio; Lai, Andrew; Nardo, Lorenzo; Facchetti, Luca; Pasco, Courtney; Zhang, Chiyuan A; Han, Misung; Parrott, Amanda Hutton; Tien, Phyllis; Krug, Roland

2018-02-01

There is evidence that human immunodeficiency virus (HIV) infection and antiretroviral therapy (ART) are independent risk factors for osteoporosis and fracture which is not solely explained by changes in bone mineral density. Thus, we hypothesized that the assessment of trabecular microstructure might play an important role for bone quality in this population and might explain the increased fracture risk. In this study, we have assessed bone microstructure in the proximal femur using high-resolution magnetic resonance imaging (MRI) as well as in the extremities using high resolution peripheral quantitative computed tomography (HR-pQCT) in HIV-infected men and healthy controls and compared these findings to those based on areal bone mineral density (aBMD) derived from dual X-ray absorptiometry (DXA) which is the standard clinical parameter for the diagnosis of osteoporosis. Eight HIV-infected men and 11 healthy age-matched controls were recruited and informed consent was obtained before each scan. High-resolution MRI of the proximal femur was performed using fully balanced steady state free precession (bSSFP) on a 3T system. Three volumes of interest at corresponding anatomic locations across all subjects were defined based on registrations of a common template. Four MR-based trabecular microstructural parameters were analyzed at each region: fuzzy bone volume fraction (f-BVF), trabecular number (Tb.N), thickness (Tb.Th), and spacing (Tb.Sp). In addition, the distal radius and distal tibia were imaged with HR-pQCT. Four HR-pQCT-based microstructural parameters were analyzed: trabecular bone volume fraction (BV/TV), Tb.N, Tb.Th, and Tb.Sp. Total hip and spine aBMD were determined from DXA. Microstructural bone parameters derived from MRI at the proximal femur and from HR-pQCT at the distal tibia showed significantly lower bone quality in HIV-infected patients compared to healthy controls. In contrast, DXA aBMD data showed no significant differences between HIV

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

PubMed Central

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

2016-01-01

Atomic minerals are the smallest components of bone and the content of Ca, being the most abundant mineral in bone, correlates strongly with the risk of osteoporosis. Postmenopausal women have a far greater risk of suffering from OP due to low Ca concentrations in their bones and this is associated with low bone mass and higher bone fracture rates. However, bone strength is determined not only by Ca level, but also a number of metallic and non-metallic elements in bone. Thus, in this study, the difference of metallic and non-metallic elements in ovariectomy-induced osteoporosis tibial and maxillary trabecular bone was investigated in comparison with sham operated normal bone by laser ablation inductively-coupled plasma mass spectrometry using a rat model. The results demonstrated that the average concentrations of 25Mg, 28Si, 39K, 47Ti, 56Fe, 59Co, 77Se, 88Sr, 137Ba, and 208Pb were generally higher in tibia than those in maxilla. Compared with the sham group, Ovariectomy induced more significant changes of these elements in tibia than maxilla, indicating tibial trabecular bones are more sensitive to changes of circulating estrogen. In addition, the concentrations of 28Si, 77Se, 208Pb, and Ca/P ratios were higher in tibia and maxilla in ovariectomised rats than those in normal bone at all time-points. The present study indicates that ovariectomy could significantly impact the element distribution and concentrations between tibia and maxilla. PMID:27338361

[The effects of epinephrine and adrenergic antagonists on adenosine 3', 5'-monophosphate level of bovine trabecular cells in vitro].

PubMed

Lu, Y; Li, M; Shen, Y

1998-03-01

To determine the effects of epinephrine (EPI) and adrenergic antagonists on adenosine 3', 5'-monophosphate (cAMP) level of bovine trabecular cells (BTC) in vitro. (3)H-cAMP was used in protein binding assay for measuring the intracellular level of cAMP. (1) 10(-5) mol/L EPI induced a fold increase of cAMP in cultured BTC in vitro; (2) Timilol and ICI 118, 551 blocked efficiently the effect of EPI at a lower concentration (10(-6) mol/L). (3) Bisoprolol did not efficiently block the effect of EPI unless at high concentrations (>or= 10(-5) mol/L). The effects of EPI increasing outflow facility may be associated with its increase of cAMP in trabecular cells; BTC contains beta-adrenergic receptors, and beta(2)-adrenergic receptors are dominant.

Ultrasound melted polymer sleeve for improved screw anchorage in trabecular bone--A novel screw augmentation technique.

PubMed

Schmoelz, W; Mayr, R; Schlottig, F; Ivanovic, N; Hörmann, R; Goldhahn, J

2016-03-01

Screw anchorage in osteoporotic bone is still limited and makes treatment of osteoporotic fractures challenging for surgeons. Conventional screws fail in poor bone quality due to loosening at the screw-bone interface. A new technology should help to improve this interface. In a novel constant amelioration process technique, a polymer sleeve is melted by ultrasound in the predrilled screw hole prior to screw insertion. The purpose of this study was to investigate in vitro the effect of the constant amelioration process platform technology on primary screw anchorage. Fresh frozen femoral heads (n=6) and vertebrae (n=6) were used to measure the maximum screw insertion torque of reference and constant amelioration process augmented screws. Specimens were cut in cranio-caudal direction, and the screws (reference and constant amelioration process) were implanted in predrilled holes in the trabecular structure on both sides of the cross section. This allowed the pairwise comparison of insertion torque for constant amelioration process and reference screws (femoral heads n=18, vertebrae n=12). Prior to screw insertion, a micro-CT scan was made to ensure comparable bone quality at the screw placement location. The mean insertion torque for the constant amelioration process augmented screws in both, the femoral heads (44.2 Ncm, SD 14.7) and the vertebral bodies (13.5 Ncm, SD 6.3) was significantly higher than for the reference screws of the femoral heads (31.7 Ncm, SD 9.6, p<0.001) and the vertebral bodies (7.1 Ncm, SD 4.5, p<0.001). The interconnection of the melted polymer sleeve with the surrounding trabecular bone in the constant amelioration process technique resulted in a higher screw insertion torque and can improve screw anchorage in osteoporotic trabecular bone. Copyright © 2016 Elsevier Ltd. All rights reserved.

Evolution of bone disease after kidney transplantation: A prospective histomorphometric analysis of trabecular and cortical bone.

PubMed

Carvalho, Catarina; Magalhães, Juliana; Pereira, Luciano; Simões-Silva, Liliana; Castro-Ferreira, Inês; Frazão, João Miguel

2016-01-01

Post-transplant bone disease results from multiple factors, including previous bone and mineral metabolism disturbances and effects from transplant-related medications. Bone biopsy remains the gold-standard diagnostic tool. We aimed to prospectively evaluate trabecular and cortical bone by histomorphometry after kidney transplantation. Seven patients, willing to perform follow-up bone biopsy, were included in the study. Dual-X-ray absorptiometry and trans-iliac bone biopsy were performed within the first 2 months after renal transplantation and repeated after 2-5 years of follow-up. Follow-up biopsy revealed a significant decrease in osteoblast surface/bone surface (0.91 ± 0.81 to 0.47 ± 0.12%, P = 0.036), osteoblasts number/bone surface (0.45 (0.23, 0.94) to 0.00/mm(2) , P = 0.018) and erosion surface/bone surface (3.75 ± 2.02 to 2.22 ± 1.38%, P = 0.044). A decrease in trabecular number (3.55 (1.81, 2.89) to 1.55/mm (1.24, 2.06), P = 0.018) and increase in trabecular separation (351.65 ± 135.04 to 541.79 ± 151.91 μm, P = 0.024) in follow-up biopsy suggest loss in bone quantity. We found no significant differences in cortical analysis, except a reduction in external cortical osteonal eroded surface (5.76 (2.94, 13.97) to 3.29% (0.00, 6.67), P = 0.043). Correlations between bone histomorphometric and dual-X-ray absorptiometry parameters gave inconsistent results. The results show a reduction in bone activity, suggesting increased risk of adynamic bone and loss of bone volume. Cortical bone seems less affected by post-transplant biological changes in the first years after kidney transplantation. © 2015 Asian Pacific Society of Nephrology.

Skeletal development of mice lacking bone sialoprotein (BSP)--impairment of long bone growth and progressive establishment of high trabecular bone mass.

PubMed

Bouleftour, Wafa; Boudiffa, Maya; Wade-Gueye, Ndeye Marième; Bouët, Guénaëlle; Cardelli, Marco; Laroche, Norbert; Vanden-Bossche, Arnaud; Thomas, Mireille; Bonnelye, Edith; Aubin, Jane E; Vico, Laurence; Lafage-Proust, Marie Hélène; Malaval, Luc

2014-01-01

Adult Ibsp-knockout mice (BSP-/-) display shorter stature, lower bone turnover and higher trabecular bone mass than wild type, the latter resulting from impaired bone resorption. Unexpectedly, BSP knockout also affects reproductive behavior, as female mice do not construct a proper "nest" for their offsprings. Multiple crossing experiments nonetheless indicated that the shorter stature and lower weight of BSP-/- mice, since birth and throughout life, as well as their shorter femur and tibia bones are independent of the genotype of the mothers, and thus reflect genetic inheritance. In BSP-/- newborns, µCT analysis revealed a delay in membranous primary ossification, with wider cranial sutures, as well as thinner femoral cortical bone and lower tissue mineral density, reflected in lower expression of bone formation markers. However, trabecular bone volume and osteoclast parameters of long bones do not differ between genotypes. Three weeks after birth, osteoclast number and surface drop in the mutants, concomitant with trabecular bone accumulation. The growth plates present a thinner hypertrophic zone in newborns with lower whole bone expression of IGF-1 and higher IHH in 6 days old BSP-/- mice. At 3 weeks the proliferating zone is thinner and the hypertrophic zone thicker in BSP-/- than in BSP+/+ mice of either sex, maybe reflecting a combination of lower chondrocyte proliferation and impaired cartilage resorption. Six days old BSP-/- mice display lower osteoblast marker expression but higher MEPE and higher osteopontin(Opn)/Runx2 ratio. Serum Opn is higher in mutants at day 6 and in adults. Thus, lack of BSP alters long bone growth and membranous/cortical primary bone formation and mineralization. Endochondral development is however normal in mutant mice and the accumulation of trabecular bone observed in adults develops progressively in the weeks following birth. Compensatory high Opn may allow normal endochondral development in BSP-/- mice, while impairing

Osteocyte viability and regulation of osteoblast function in a 3D trabecular bone explant under dynamic hydrostatic pressure.

PubMed

Takai, Erica; Mauck, Robert L; Hung, Clark T; Guo, X Edward

2004-09-01

A new trabecular bone explant model was used to examine osteocyte-osteoblast interactions under DHP loading. DHP loading enhanced osteocyte viability as well as osteoblast function measured by osteoid formation. However, live osteocytes were necessary for osteoblasts to form osteoids in response to DHP, which directly show osteoblast-osteocyte interactions in this in vitro culture. A trabecular bone explant model was characterized and used to examine the effect of osteocyte and osteoblast interactions and dynamic hydrostatic pressure (DHP) loading on osteocyte viability and osteoblast function in long-term culture. Trabecular bone cores obtained from metacarpals of calves were cleaned of bone marrow and trabecular surface cells and divided into six groups, (1) live cores + dynamic hydrostatic pressure (DHP), (2) live cores + sham, (3) live cores + osteoblast + DHP, (4) live cores + osteoblast + sham, (5) devitalized cores + osteoblast + DHP, and (6) devitalized cores + osteoblast + sham, with four culture durations (2, 8, 15, and 22 days; n = 4/group). Cores from groups 3-6 were seeded with osteoblasts, and cores from groups 5 and 6 were devitalized before seeding. Groups 1, 3, and 5 were subjected to daily DHP loading. Bone histomorphometry was performed to quantify osteocyte viability based on morphology and to assess osteoblast function based on osteoid surface per bone surface (Os/Bs). TUNEL staining was performed to evaluate the mode of osteocyte death under various conditions. A portion of osteocytes remained viable for the duration of culture. DHP loading significantly enhanced osteocyte viability up to day 8, whereas the presence of seeded osteoblasts significantly decreased osteocyte viability. Cores with live osteocytes showed higher Os/Bs compared with devitalized cores, which reached significant levels over a greater range of time-points when combined with DHP loading. DHP loading did not increase Os/Bs in the absence of live osteocytes. The percentage

Tributyltin induces distinct effects on cortical and trabecular bone in female C57Bl/6J mice.

PubMed

Watt, James; Baker, Amelia H; Meeks, Brett; Pajevic, Paola D; Morgan, Elise F; Gerstenfeld, Louis C; Schlezinger, Jennifer J

2018-09-01

The retinoid X receptors (RXR), peroxisome proliferator activated receptor gamma (PPARγ), and liver X receptors (LXR) all have been shown to regulate bone homeostasis. Tributyltin (TBT) is an environmental contaminant that is a dual RXRα/β and PPARγ agonist. TBT induces RXR, PPARγ, and LXR-mediated gene transcription and suppresses osteoblast differentiation in vitro. Bone marrow multipotent mesenchymal stromal cells derived from female C57BL/6J mice were more sensitive to suppression of osteogenesis by TBT than those derived from male mice. In vivo, oral gavage of 12 week old female, C57Bl/6J mice with 10 mg/kg TBT for 10 weeks resulted in femurs with a smaller cross-sectional area and thinner cortex. Surprisingly, TBT induced significant increases in trabecular thickness, number, and bone volume fraction. TBT treatment did not change the Rankl:Opg RNA ratio in whole bone, and histological analyses showed that osteoclasts in the trabecular space were minimally reduced. In contrast, expression of cardiotrophin-1, an osteoblastogenic cytokine secreted by osteoclasts, increased. In primary bone marrow macrophage cultures, TBT marginally inhibited the number of osteoclasts that differentiated, in spite of significantly suppressing expression of osteoclast markers Nfatc1, Acp5, and Ctsk and resorptive activity. TBT induced expression of RXR- and LXR-dependent genes in whole bone and in vitro osteoclast cultures. However, only an RXR antagonist, but not an LXR antagonist, significantly inhibited TBTs ability to suppress osteoclast differentiation. These results suggest that TBT has distinct effects on cortical versus trabecular bone, likely resulting from independent effects on osteoblast and osteoclast differentiation that are mediated through RXR. © 2018 Wiley Periodicals, Inc.

Loss of BMP signaling through BMPR1A in osteoblasts leads to greater collagen cross-link maturation and material-level mechanical properties in mouse femoral trabecular compartments

PubMed Central

Zhang, Yanshuai; McNerny, Erin Gatenby; Terajima, Masahiko; Raghavan, Mekhala; Romanowicz, Genevieve; Zhang, Zhanpeng; Zhang, Honghao; Kamiya, Nobuhiro; Tantillo, Margaret; Zhu, Peizhi; Scott, Gregory J.; Ray, Manas K.; Lynch, Michelle; Ma, Peter X.; Morris, Michael D.; Yamauchi, Mitsuo; Kohn, David H.; Mishina, Yuji

2016-01-01

Bone morphogenetic protein (BMP) signaling pathways play critical roles in skeletal development and new bone formation. Our previous study, however, showed a negative impact of BMP signaling on bone mass because of the osteoblast-specific loss of a BMP receptor (i.e. BMPR1A) showing increased trabecular bone volume and mineral density in mice. Here, we investigated the bone quality and biomechanical properties of the higher bone mass associated with BMPR1A deficiency using the osteoblast-specific Bmpr1a conditional knockout (cKO) mouse model. Collagen biochemical analysis revealed greater levels of the mature cross-link pyridinoline in the cKO bones, in parallel with upregulation of collagen modifying enzymes. Raman spectroscopy distinguished increases in the mature to immature cross-link ratio and mineral to matrix ratio in the trabecular compartments of cKO femora, but not in the cortical compartments. The mineral crystallinity was unchanged in the cKO in either the trabecular or cortical compartments. Further, we tested the intrinsic material properties by nanoindentation and found significantly higher hardness and elastic modulus in the cKO trabecular compartments, but not in the cortical compartments. Four point bending tests of cortical compartments showed lower structural biomechanical properties (i.e. strength and stiffness) in the cKO bones due to the smaller cortical areas. However, there were no significant differences in biomechanical performance at the material level, which was consistent with the nanoindentation test results on the cortical compartment. These studies emphasize the pivotal role of BMPR1A in the determination of bone quality and mechanical integrity under physiological conditions, with different impact on femoral cortical and trabecular compartments. PMID:27113526

Imaging the Effects of Prostaglandin Analogues on Cultured Trabecular Meshwork Cells by Coherent Anti-Stokes Raman Scattering

PubMed Central

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

2013-01-01

Purpose. The aim of this study was to nondestructively monitor morphological changes to the lipid membranes of primary cultures of living human trabecular meshwork cells (hTMC) without the application of exogenous label. Methods. Live hTMC were imaged using two nonlinear optical techniques: coherent anti-Stokes Raman scattering (CARS) and two-photon autofluorescence (TPAF). The hTMC were treated with a commercial formulation of latanoprost (0.5 μg/mL) for 24 hours before imaging. Untreated cells and cells treated with vehicle containing the preservative benzalkonium chloride (BAK; 2 μg/mL) were imaged as controls. After CARS/TPAF imaging, hTMC were fixed, stained with the fluorescent lipid dye Nile Red, and imaged by conventional confocal microscopy to verify lipid membrane structures. Results. Analysis of CARS/TPAF images of hTMC treated with latanoprost revealed multiple intracellular lipid membranes absent from untreated or BAK-treated hTMC. Treatment of hTMC with sodium fluoride or ouabain, agents shown to cause morphological changes to hTMC, also did not induce formation of intracellular lipid membranes. Conclusions. CARS microscopy detected changes in living hTMC morphology that were validated by subsequent histological stain. Prostaglandin-induced changes to hTMC involved rearrangement of lipid membranes within these cells. These in vitro results identify a novel biological response to a class of antiglaucoma drugs, and further experiments are needed to establish how this effect is involved in the hypotensive action of prostaglandin analogues in vivo. PMID:23900606

Spontaneous mutation of Dock7 results in lower trabecular bone mass and impaired periosteal expansion in aged female Misty mice.

PubMed

Le, Phuong T; Bishop, Kathleen A; Maridas, David E; Motyl, Katherine J; Brooks, Daniel J; Nagano, Kenichi; Baron, Roland; Bouxsein, Mary L; Rosen, Clifford J

2017-12-01

Misty mice (m/m) have a loss of function mutation in Dock7 gene, a guanine nucleotide exchange factor, resulting in low bone mineral density, uncoupled bone remodeling and reduced bone formation. Dock7 has been identified as a modulator of osteoblast number and in vitro osteogenic differentiation in calvarial osteoblast culture. In addition, m/m exhibit reduced preformed brown adipose tissue innervation and temperature as well as compensatory increase in beige adipocyte markers. While the low bone mineral density phenotype is in part due to higher sympathetic nervous system (SNS) drive in young mice, it is unclear what effect aging would have in mice homozygous for the mutation in the Dock7 gene. We hypothesized that age-related trabecular bone loss and periosteal envelope expansion would be altered in m/m. To test this hypothesis, we comprehensively characterized the skeletal phenotype of m/m at 16, 32, 52, and 78wks of age. When compared to age-matched wild-type control mice (+/+), m/m had lower areal bone mineral density (aBMD) and areal bone mineral content (aBMC). Similarly, both femoral and vertebral BV/TV, Tb.N, and Conn.D were decreased in m/m while there was also an increase in Tb.Sp. As low bone mineral density and decreased trabecular bone were already present at 16wks of age in m/m and persisted throughout life, changes in age-related trabecular bone loss were not observed highlighting the role of Dock7 in controlling trabecular bone acquisition or bone loss prior to 16wks of age. Cortical thickness was also lower in the m/m across all ages. Periosteal and endosteal circumferences were higher in m/m compared to +/+ at 16wks. However, endosteal and periosteal expansion were attenuated in m/m, resulting in m/m having lower periosteal and endosteal circumferences by 78wks of age compared to +/+, highlighting the critical role of Dock7 in appositional bone expansion. Histomorphometry revealed that osteoblasts were nearly undetectable in m/m and marrow

The Effect of Changing Scan Mode on Trabecular Bone Score Using Lunar Prodigy.

PubMed

Chen, Weiwen; Slattery, Anthony; Center, Jacqueline; Pocock, Nicholas

2016-10-01

Trabecular bone score (TBS) is a measure of gray scale homogeneity that correlates with trabecular microarchitecture and is an independent predictor of fracture risk. TBS is being increasingly used in the assessment of patients at risk of osteoporosis and has recently been incorporated into FRAX ® . GE Lunar machines acquire spine scans using 1 of 3 acquisition modes depending on abdominal tissue thickness (thin, standard, and thick). From a database review, 30 patients (mean body mass index: 30.8, range 26.2-34.1) were identified who had undergone lumbar spine DXA scans (GE Lunar Prodigy, software 14.10; Lunar Radiation Corporation, Madison, WI) in both standard mode and thick mode, on the same day with no repositioning. Lumbar spine bone mineral density (L1-L4) and TBS were derived from the 30 paired spine scans. There was no significant difference in lumbar spine bone mineral density between the 2 scanning modes. There were, however, significant higher TBS values from the spine scans acquired in thick mode compared to the TBS values derived from spine acquisitions in standard mode (mean TBS difference: 0.24 [20%], standard deviation ±0.10). In conclusion, these preliminary data suggest that TBS values acquired in the GE Lunar Prodigy are dependent on the scanning mode used. Further evaluation is required to confirm the cause and develop appropriate protocols. Copyright © 2016 International Society for Clinical Densitometry. Published by Elsevier Inc. All rights reserved.

Human trabecular meshwork cells express BMP antagonist mRNAs and proteins.

PubMed

Tovar-Vidales, Tara; Fitzgerald, Ashley M; Clark, Abbot F

2016-06-01

Glaucoma patients have elevated aqueous humor and trabecular meshwork (TM) levels of transforming growth factor-beta2 (TGF-β2). TGF-β2 has been associated with increased extracellular matrix (ECM) deposition (i.e. fibronectin), which is attributed to the increased resistance of aqueous humor outflow through the TM. We have previously demonstrated that bone morphogenetic protein (BMP) 4 selectively counteracts the profibrotic effect of TGF-β2 with respect to ECM synthesis in the TM, and this action is reversed by the BMP antagonist gremlin. Thus, the BMP and TGF-β signaling pathways antagonize each other's antifibrotic and profibrotic roles. The purpose of this study was to determine whether cultured human TM cells: (a) express other BMP antagonists including noggin, chordin, BMPER, BAMBI, Smurf1 and 2, and (b) whether expression of these proteins is regulated by exogenous TGF-β2 treatment. Primary human trabecular meshwork (TM) cells were grown to confluency and treated with TGF-β2 (5 ng/ml) for 24 or 48 h in serum-free medium. Untreated cell served as controls. qPCR and Western immunoblots (WB) determined that human TM cells expressed mRNAs and proteins for the BMP antagonist proteins: noggin, chordin, BMPER, BAMBI, and Smurf1/2. Exogenous TGF-β2 decreased chordin, BMPER, BAMBI, and Smurf1 mRNA and protein expression. In contrast, TGF-β2 increased secreted noggin and Smurf2 mRNA and protein levels. BMP antagonist members are expressed in the human TM. These molecules may be involved in the normal function of the TM as well as TM pathogenesis. Altered expression of BMP antagonist members may lead to functional changes in the human TM. Copyright © 2016 Elsevier Ltd. All rights reserved.

Advisory Council on Historic Preservation: Preserving America's Heritage

Science.gov Websites

Advisory Council on Historic Preservation The Advisory Council on Historic Preservation promotes the preservation, enhancement, and sustainable use of our nation's diverse historic resources, and advises the President and the Congress on national historic preservation policy. ACHP logo Preserving

Trabecular bone score (TBS): Method and applications.

PubMed

Martineau, P; Leslie, W D

2017-11-01

Trabecular bone score (TBS) is a texture index derived from standard lumbar spine dual energy X-ray absorptiometry (DXA) images and provides information about the underlying bone independent of the bone mineral density (BMD). Several salient observations have emerged. Numerous studies have examined the relationship between TBS and fracture risk and have shown that lower TBS values are associated with increased risk for major osteoporotic fracture in postmenopausal women and older men, with this result being independent of BMD values and other clinical risk factors. Therefore, despite being derived from standard DXA images, the information contained in TBS is independent and complementary to the information provided by BMD and the FRAX® tool. A procedure to generate TBS-adjusted FRAX probabilities has become available with the resultant predicted fracture risks shown to be more accurate than the standard FRAX tool. With these developments, TBS has emerged as a clinical tool for improved fracture risk prediction and guiding decisions regarding treatment initiation, particularly for patients with FRAX probabilities around an intervention threshold. In this article, we review the development, validation, clinical application, and limitations of TBS. Copyright © 2017 Elsevier Inc. All rights reserved.

A new constitutive model for simulation of softening, plateau, and densification phenomena for trabecular bone under compression.

PubMed

Lee, Chi-Seung; Lee, Jae-Myung; Youn, BuHyun; Kim, Hyung-Sik; Shin, Jong Ki; Goh, Tae Sik; Lee, Jung Sub

2017-01-01

A new type of constitutive model and its computational implementation procedure for the simulation of a trabecular bone are proposed in the present study. A yield surface-independent Frank-Brockman elasto-viscoplastic model is introduced to express the nonlinear material behavior such as softening beyond yield point, plateau, and densification under compressive loads. In particular, the hardening- and softening-dominant material functions are introduced and adopted in the plastic multiplier to describe each nonlinear material behavior separately. In addition, the elasto-viscoplastic model is transformed into an implicit type discrete model, and is programmed as a user-defined material subroutine in commercial finite element analysis code. In particular, the consistent tangent modulus method is proposed to improve the computational convergence and to save computational time during finite element analysis. Through the developed material library, the nonlinear stress-strain relationship is analyzed qualitatively and quantitatively, and the simulation results are compared with the results of compression test on the trabecular bone to validate the proposed constitutive model, computational method, and material library. Copyright © 2016 Elsevier Ltd. All rights reserved.

Bone Loss from High Repetitive High Force Loading is Prevented by Ibuprofen Treatment

PubMed Central

Jain, Nisha X.; Barr-Gillespie, Ann E.; Clark, Brian D.; Kietrys, David M.; Wade, Christine K.; Litvin, Judith; Popoff, Steven N.; Barbe, Mary F.

2014-01-01

We examined roles of loading and inflammation on forearm bones in a rat model of upper extremity overuse. Trabecular structure in distal radius and ulna was examined in three groups of young adult rats: 1) 5% food-restricted that underwent an initial training period of 10 min/day for 5 weeks to learn the repetitive task (TRHF); 2) rats that underwent the same training before performing a high repetition high force task, 2 hours/day for 12 weeks (HRHF); and 3) food-restricted only (FRC). Subsets were treated with oral ibuprofen (IBU). TRHF rats had increased trabecular bone volume and numbers, osteoblasts, and serum osteocalcin, indicative of bone adaptation. HRHF rats had constant muscle pulling forces, showed limited signs of bone adaptation, but many signs of bone resorption, including decreased trabecular bone volume and bone mineral density, increased osteoclasts and bone inflammatory cytokines, and reduced median nerve conduction velocity (15%). HRHF+IBU rats showed no trabecular resorptive changes, no increased osteoclasts or bone inflammatory cytokines, no nerve inflammation, preserved nerve conduction, and increased muscle voluntary pulling forces. Ibuprofen treatment preserved trabecular bone quality by reducing osteoclasts and bone inflammatory cytokines, and improving muscle pulling forces on bones as a result of reduced nerve inflammation. PMID:24583543

Comparison of diffraction-enhanced computed tomography and monochromatic synchrotron radiation computed tomography of human trabecular bone.

PubMed

Connor, D M; Hallen, H D; Lalush, D S; Sumner, D R; Zhong, Z

2009-10-21

Diffraction-enhanced imaging (DEI) is an x-ray-based medical imaging modality that, when used in tomography mode (DECT), can generate a three-dimensional map of both the apparent absorption coefficient and the out-of-plane gradient of the index of refraction of the sample. DECT is known to have contrast gains over monochromatic synchrotron radiation CT (SRCT) for soft tissue structures. The goal of this experiment was to compare contrast-to-noise ratio (CNR) and resolution in images of human trabecular bone acquired using SRCT with images acquired using DECT. All images were acquired at the National Synchrotron Light Source (Upton, NY, USA) at beamline X15 A at an x-ray energy of 40 keV and the silicon [3 3 3] reflection. SRCT, apparent absorption DECT and refraction DECT slice images of the trabecular bone were created. The apparent absorption DECT images have significantly higher spatial resolution and CNR than the corresponding SRCT images. Thus, DECT will prove to be a useful tool for imaging applications in which high contrast and high spatial resolution are required for both soft tissue features and bone.

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

PubMed

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

2013-04-01

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

In vitro and in vivo MR evaluation of internal gradient to assess trabecular bone density

NASA Astrophysics Data System (ADS)

De Santis, S.; Rebuzzi, M.; Di Pietro, G.; Fasano, F.; Maraviglia, B.; Capuani, S.

2010-10-01

Here we propose a new magnetic resonance (MR) strategy based on the evaluation of internal gradient (Gi) to assess the trabecular bone (TB) density in spongy bone. Spongy bone is a porous system characterized by a solid trabecular network immersed in bone marrow and characterized by a different relative percentage of water and fats. Using a 9.4 T MR micro-imaging system, we first evaluated the relative water and fat Gi as extracted from the Spin-Echo decay function in vitro of femoral head samples from calves. Indeed, the differential effects of fat and water diffusion result in different types of Gi behavior. Using a clinical MR 3T scanner, we then investigated in vivo the calcanei of individuals characterized by different known TB densities. We demonstrate, on these samples, that water is more prevalent in the boundary zone, while fats are rearranged primarily in the central zone of each pore. In vitro experiments showed that water Gi magnitude from the samples was directly proportional to their TB density. Similar behavior was also observed in the clinical measures. Conversely, fat Gi did not provide any information on spongy-bone density. Our results suggest that water Gi may be a reliable marker to assess the status of spongy bone.

Correlative Analysis of Vertebral Trabecular Bone Microarchitecture and Mechanical Properties: A Combined Ultra-high Field (7 Tesla) MRI and Biomechanical Investigation.

PubMed

Guenoun, Daphne; Fouré, Alexandre; Pithioux, Martine; Guis, Sandrine; Le Corroller, Thomas; Mattei, Jean-Pierre; Pauly, Vanessa; Guye, Maxime; Bernard, Monique; Chabrand, Patrick; Champsaur, Pierre; Bendahan, David

2017-10-15

High-resolution imaging and biomechanical investigation of ex-vivo vertebrae. The aim of this study was to assess bone microarchitecture of cadaveric vertebrae using ultra-high field (UHF) 7 Tesla magnetic resonance imaging (MRI) and to determine whether the corresponding microarchitecture parameters were related to bone mineral density (BMD) and bone strength assessed by dual-energy x-ray absorptiometry (DXA) and mechanical compression tests. Limitations of DXA for the assessment of bone fragility and osteoporosis have been recognized and criteria of microarchitecture alteration have been included in the definition of osteoporosis. Although vertebral fracture is the most common osteoporotic fracture, no study has assessed directly vertebral trabecular bone microarchitecture. BMD of 24 vertebrae (L2, L3, L4) from eight cadavers was investigated using DXA. The bone volume fraction (BVF), trabecular thickness (Tb.Th), and trabecular spacing (Tb.Sp) of each vertebra were quantified using UHF MRI. Measurements were performed by two operators to characterize the inter-rater reliability. The whole set of specimens underwent mechanical compression tests to failure and the corresponding failure stress was calculated. The inter-rater reliability for bone microarchitecture parameters was good with intraclass correlation coefficients ranging from 0.82 to 0.94. Failure load and stress were significantly correlated with BVF, Tb.Sp, and BMD (P < 0.05). Tb.Th was only correlated with the failure stress (P < 0.05). Multiple regression analysis demonstrated that the combination of BVF and BMD improved the prediction of the failure stress from an adjusted R = 0.384 for BMD alone to an adjusted R = 0.414. We demonstrated for the first time that the vertebral bone microarchitecture assessed with UHF MRI was significantly correlated with biomechanical parameters. Our data suggest that the multimodal assessment of BMD and trabecular bone microarchitecture with UHF MRI

Skeletal dosimetry: A hyperboloid representation of the bone-marrow interface to reduce voxel effects in three-dimensional images of trabecular bone

NASA Astrophysics Data System (ADS)

Rajon, Didier Alain

Radiation damage to the hematopoietic bone marrow is clearly defined as the limiting factor to the development of internal emitter therapies. Current dosimetry models rely on chord-length distributions measured through the complex microstructure of the trabecular bone regions of the skeleton in which most of the active marrow is located. Recently, Nuclear Magnetic Resonance (NMR) has been used to obtain high-resolution three-dimensional (3D) images of small trabecular bone samples. These images have been coupled with computer programs to estimate dosimetric parameters such as chord-length distributions, and energy depositions by monoenergetic electrons. This new technique is based on the assumption that each voxel of the image is assigned either to bone tissue or to marrow tissue after application of a threshold value. Previous studies showed that this assumption had important consequences on the outcome of the computer calculations. Both the chord-length distribution measurements and the energy deposition calculations are subject to voxel effects that are responsible for large discrepancies when applied to mathematical models of trabecular bone. The work presented in this dissertation proposes first a quantitative study of the voxel effects. Consensus is that the voxelized representation of surfaces should not be used as direct input to dosimetry computer programs. Instead we need a new technique to transform the interfaces into smooth surfaces. The Marching Cube (MC) algorithm was used and adapted to do this transformation. The initial image was used to generate a continuous gray-level field throughout the image. The interface between bone and marrow was then simulated by the iso-gray-level surface that corresponds to a predetermined threshold value. Calculations were then performed using this new representation. Excellent results were obtained for both the chord-length distribution and the energy deposition measurements. Voxel effects were reduced to an

Trabecular Bone Strength Predictions of HR-pQCT and Individual Trabeculae Segmentation (ITS)-Based Plate and Rod Finite Element Model Discriminate Postmenopausal Vertebral Fractures

PubMed Central

Liu, X. Sherry; Wang, Ji; Zhou, Bin; Stein, Emily; Shi, Xiutao; Adams, Mark; Shane, Elizabeth; Guo, X. Edward

2013-01-01

While high-resolution peripheral quantitative computed tomography (HR-pQCT) has advanced clinical assessment of trabecular bone microstructure, nonlinear microstructural finite element (μFE) prediction of yield strength by HR-pQCT voxel model is impractical for clinical use due to its prohibitively high computational costs. The goal of this study was to develop an efficient HR-pQCT-based plate and rod (PR) modeling technique to fill the unmet clinical need for fast bone strength estimation. By using individual trabecula segmentation (ITS) technique to segment the trabecular structure into individual plates and rods, a patient-specific PR model was implemented by modeling each trabecular plate with multiple shell elements and each rod with a beam element. To validate this modeling technique, predictions by HR-pQCT PR model were compared with those of the registered high resolution μCT voxel model of 19 trabecular sub-volumes from human cadaveric tibiae samples. Both Young’s modulus and yield strength of HR-pQCT PR models strongly correlated with those of μCT voxel models (r2=0.91 and 0.86). Notably, the HR-pQCT PR models achieved major reductions in element number (>40-fold) and CPU time (>1,200-fold). Then, we applied PR model μFE analysis to HR-pQCT images of 60 postmenopausal women with (n=30) and without (n=30) a history of vertebral fracture. HR-pQCT PR model revealed significantly lower Young’s modulus and yield strength at the radius and tibia in fracture subjects compared to controls. Moreover, these mechanical measurements remained significantly lower in fracture subjects at both sites after adjustment for aBMD T-score at the ultradistal radius or total hip. In conclusion, we validated a novel HR-pQCT PR model of human trabecular bone against μCT voxel models and demonstrated its ability to discriminate vertebral fracture status in postmenopausal women. This accurate nonlinear μFE prediction of HR-pQCT PR model, which requires only seconds of

Chitosan nanofiber scaffold improves bone healing via stimulating trabecular bone production due to upregulation of the Runx2/osteocalcin/alkaline phosphatase signaling pathway

PubMed Central

Ho, Ming-Hua; Yao, Chih-Jung; Liao, Mei-Hsiu; Lin, Pei-I; Liu, Shing-Hwa; Chen, Ruei-Ming

2015-01-01

Osteoblasts play critical roles in bone formation. Our previous study showed that chitosan nanofibers can stimulate osteoblast proliferation and maturation. This translational study used an animal model of bone defects to evaluate the effects of chitosan nanofiber scaffolds on bone healing and the possible mechanisms. In this study, we produced uniform chitosan nanofibers with fiber diameters of approximately 200 nm. A bone defect was surgically created in the proximal femurs of male C57LB/6 mice, and then the left femur was implanted with chitosan nanofiber scaffolds for 21 days and compared with the right femur, which served as a control. Histological analyses revealed that implantation of chitosan nanofiber scaffolds did not lead to hepatotoxicity or nephrotoxicity. Instead, imaging analyses by X-ray transmission and microcomputed tomography showed that implantation of chitosan nanofiber scaffolds improved bone healing compared with the control group. In parallel, microcomputed tomography and bone histomorphometric assays further demonstrated augmentation of the production of new trabecular bone in the chitosan nanofiber-treated group. Furthermore, implantation of chitosan nanofiber scaffolds led to a significant increase in the trabecular bone thickness but a reduction in the trabecular parameter factor. As to the mechanisms, analysis by confocal microscopy showed that implantation of chitosan nanofiber scaffolds increased levels of Runt-related transcription factor 2 (Runx2), a key transcription factor that regulates osteogenesis, in the bone defect sites. Successively, amounts of alkaline phosphatase and osteocalcin, two typical biomarkers that can simulate bone maturation, were augmented following implantation of chitosan nanofiber scaffolds. Taken together, this translational study showed a beneficial effect of chitosan nanofiber scaffolds on bone healing through stimulating trabecular bone production due to upregulation of Runx2-mediated alkaline

Microarchitectural Deterioration of Cortical and Trabecular Bone: Differing Effects of Denosumab and Alendronate

PubMed Central

Seeman, Ego; Delmas, Pierre D; Hanley, David A; Sellmeyer, Deborah; Cheung, Angela M; Shane, Elizabeth; Kearns, Ann; Thomas, Thierry; Boyd, Steven K; Boutroy, Stephanie; Bogado, Cesar; Majumdar, Sharmila; Fan, Michelle; Libanati, Cesar; Zanchetta, Jose

2015-01-01

The intensity of bone remodeling is a critical determinant of the decay of cortical and trabecular microstructure after menopause. Denosumab suppresses remodeling more than alendronate, leading to greater gains in areal bone mineral density (aBMD). These greater gains may reflect differing effects of each drug on bone microarchitecture and strength. In a phase 2 double-blind pilot study, 247 postmenopausal women were randomized to denosumab (60mg subcutaneous 6 monthly), alendronate (70mg oral weekly), or placebo for 12 months. All received daily calcium and vitamin D. Morphologic changes were assessed using high-resolution peripheral quantitative computed tomography (HR-pQCT) at the distal radius and distal tibia and QCT at the distal radius. Denosumab decreased serum C-telopeptide more rapidly and markedly than alendronate. In the placebo arm, total, cortical, and trabecular BMD and cortical thickness decreased (−2.1% to −0.8%) at the distal radius after 12 months. Alendronate prevented the decline (−0.6% to 2.4%, p = .051 to < .001 versus placebo), whereas denosumab prevented the decline or improved these variables (0.3% to 3.4%, p < .001 versus placebo). Changes in total and cortical BMD were greater with denosumab than with alendronate (p ≤ .024). Similar changes in these parameters were observed at the tibia. The polar moment of inertia also increased more in the denosumab than alendronate or placebo groups (p < .001). Adverse events did not differ by group. These data suggest that structural decay owing to bone remodeling and progression of bone fragility may be prevented more effectively with denosumab. PMID:20222106

Usefulness of the Trabecular Bone Score for assessing the risk of osteoporotic fracture.

PubMed

Redondo, L; Puigoriol, E; Rodríguez, J R; Peris, P; Kanterewicz, E

2018-04-01

The trabecular bone score (TBS) is an imaging technique that assesses the condition of the trabecular microarchitecture. Preliminary results suggest that TBS, along with the bone mineral density assessment, could improve the calculation of the osteoporotic fracture risk. The aim of this study was to analyse TBS values and their relationship with the clinical characteristics, bone mineral density and history of fractures of a cohort of posmenopausal women. We analysed 2,257 posmenopausal women from the FRODOS cohort, which was created to determine the risk factors for osteoporotic fracture through a clinical survey and bone densitometry with vertebral morphometry. TBS was applied to the densitometry images. TBS values ≤1230 were considered indicative of degraded microarchitecture. We performed a simple and multiple linear regression to determine the factors associated with this index. The mean TBS value in L1-L4 was 1.203±0.121. Some 55.3% of the women showed values indicating degraded microarchitecture. In the multiple linear regression analysis, the factors associated with low TBS values were age, weight, height, spinal T-score, glucocorticoid treatment, presence of type 2 diabetes and a history of fractures due to frailty. TBS showed microarchitecture degradation values in the participants of the FRODOS cohort and was associated with anthropometric factors, low bone mineral density values, the presence of fractures, a history of type 2 diabetes mellitus and the use of glucocorticoids. Copyright © 2017 Elsevier España, S.L.U. and Sociedad Española de Medicina Interna (SEMI). All rights reserved.

Trabecular Meshwork Height in Primary Open-Angle Glaucoma Versus Primary Angle-Closure Glaucoma.

PubMed

Masis, Marisse; Chen, Rebecca; Porco, Travis; Lin, Shan C

2017-11-01

To determine if trabecular meshwork (TM) height differs between primary open-angle glaucoma (POAG) and primary angle-closure glaucoma (PACG) eyes. Prospective, cross-sectional clinical study. Adult patients were consecutively recruited from glaucoma clinics at the University of California, San Francisco, from January 2012 to July 2015. Images were obtained from spectral-domain optical coherence tomography (Cirrus OCT; Carl Zeiss Meditec, Inc, Dublin, California, USA). Univariate and multivariate linear mixed models comparing TM height and glaucoma type were performed to assess the relationship between TM height and glaucoma subtype. Mixed-effects regression was used to adjust for the use of both eyes in some subjects. The study included 260 eyes from 161 subjects, composed of 61 men and 100 women. Mean age was 70 years (SD 11.77). There were 199 eyes (123 patients) in the POAG group and 61 eyes (38 patients) in the PACG group. Mean TM heights in the POAG and PACG groups were 812 ± 13 μm and 732 ± 27 μm, respectively, and the difference was significant in univariate analysis (P = .004) and in multivariate analysis (β = -88.7 [24.05-153.5]; P = .008). In this clinic-based population, trabecular meshwork height is shorter in PACG patients compared to POAG patients. This finding may provide insight into the pathophysiology of angle closure and provide assistance in future diagnosis, prevention, and management of the angle-closure spectrum of disorders. Copyright © 2017 Elsevier Inc. All rights reserved.

Low Bone Mineral Density in Male Athletes Is Associated With Bone Stress Injuries at Anatomic Sites With Greater Trabecular Composition.

PubMed

Tenforde, Adam S; Parziale, Allyson L; Popp, Kristin L; Ackerman, Kathryn E

2018-01-01

While sports participation is often associated with health benefits, a subset of athletes may develop impaired bone health. Bone stress injuries (BSIs) are a common overuse injury in athletes; site of injury has been shown to relate to underlying bone health in female athletes. Hypothesis/Purpose: This case series characterizes the association of type of sports participation and anatomic site of BSIs with low bone mineral density (BMD), defined as BMD Z-score <-1.0. Similar to female athletes, it was hypothesized that male athletes who participate in running and sustain BSIs in sites of higher trabecular bone content would be more likely to have low BMD. Cohort study; Level of evidence, 3. Chart review identified 28 male athletes aged 14 to 36 years with history of ≥1 lower-extremity BSI who were referred for evaluation of overall bone health, including assessment of lumbar spine, hip, and/or total body less head BMD per dual-energy x-ray absorptiometry. BMD Z-scores were determined via age, sex, and ethnicity normative values. Prior BSIs were classified by anatomic site of injury into trabecular-rich locations (pelvis, femoral neck, and calcaneus) and cortical-rich locations (tibia, fibula, femur, metatarsal and tarsal navicular). Sport type and laboratory values were also assessed in relationship to BMD. The association of low BMD to anatomic site of BSI and sport were evaluated with P value <.05 as threshold of significance. Of 28 athletes, 12 (43%) met criteria for low BMD. Athletes with a history of trabecular-rich BSIs had a 4.6-fold increased risk for low BMD as compared with those with only cortical-rich BSIs (9 of 11 vs 3 of 17, P = .002). Within sport type, runners had a 6.1-fold increased risk for low BMD versus nonrunners (11 of 18 vs 1 of 10, P = .016). Laboratory values, including 25-hydroxy vitamin D, were not associated with BMD or BSI location. Low BMD was identified in 43% of male athletes in this series. Athletes participating in sports of

Influence of the pore fluid on the phase velocity in bovine trabecular bone In Vitro: Prediction of the biot model

NASA Astrophysics Data System (ADS)

Lee, Kang Il

2013-01-01

The present study aims to investigate the influence of the pore fluid on the phase velocity in bovine trabecular bone in vitro. The frequency-dependent phase velocity was measured in 20 marrow-filled and water-filled bovine femoral trabecular bone samples. The mean phase velocities at frequencies between 0.6 and 1.2 MHz exhibited significant negative dispersions for both the marrow-filled and the water-filled samples. The magnitudes of the dispersions showed no significant differences between the marrow-filled and the water-filled samples. In contrast, replacement of marrow by water led to a mean increase in the phase velocity of 27 m/s at frequencies from 0.6 to 1.2 MHz. The theoretical phase velocities of the fast wave predicted by using the Biot model for elastic wave propagation in fluid-saturated porous media showed good agreements with the measurements.

Age-related mechanical strength evolution of trabecular bone under fatigue damage for both genders: Fracture risk evaluation.

PubMed

Ben Kahla, Rabeb; Barkaoui, Abdelwahed; Merzouki, Tarek

2018-08-01

Bone tissue is a living composite material, providing mechanical and homeostatic functions, and able to constantly adapt its microstructure to changes in long term loading. This adaptation is conducted by a physiological process, known as "bone remodeling". This latter is manifested by interactions between osteoclasts and osteoblasts, and can be influenced by many local factors, via effects on bone cell differentiation and proliferation. In the current work, age and gender effects on damage rate evolution, throughout life, have been investigated using a mechanobiological finite element modeling. To achieve the aim, a mathematical model has been developed, coupling both cell activities and mechanical behavior of trabecular bone, under cyclic loadings. A series of computational simulations (ABAQUS/UMAT) has been performed on a 3D human proximal femur, allowing to investigate the effects of mechanical and biological parameters on mechanical strength of trabecular bone, in order to evaluate the fracture risk resulting from fatigue damage. The obtained results revealed that mechanical stimulus amplitude affects bone resorption and formation rates, and indicated that age and gender are major factors in bone response to the applied loadings. Copyright © 2018 Elsevier Ltd. All rights reserved.

Accounting for spatial variation of trabecular anisotropy with subject-specific finite element modeling moderately improves predictions of local subchondral bone stiffness at the proximal tibia.

PubMed

Nazemi, S Majid; Kalajahi, S Mehrdad Hosseini; Cooper, David M L; Kontulainen, Saija A; Holdsworth, David W; Masri, Bassam A; Wilson, David R; Johnston, James D

2017-07-05

Previously, a finite element (FE) model of the proximal tibia was developed and validated against experimentally measured local subchondral stiffness. This model indicated modest predictions of stiffness (R 2 =0.77, normalized root mean squared error (RMSE%)=16.6%). Trabecular bone though was modeled with isotropic material properties despite its orthotropic anisotropy. The objective of this study was to identify the anisotropic FE modeling approach which best predicted (with largest explained variance and least amount of error) local subchondral bone stiffness at the proximal tibia. Local stiffness was measured at the subchondral surface of 13 medial/lateral tibial compartments using in situ macro indentation testing. An FE model of each specimen was generated assuming uniform anisotropy with 14 different combinations of cortical- and tibial-specific density-modulus relationships taken from the literature. Two FE models of each specimen were also generated which accounted for the spatial variation of trabecular bone anisotropy directly from clinical CT images using grey-level structure tensor and Cowin's fabric-elasticity equations. Stiffness was calculated using FE and compared to measured stiffness in terms of R 2 and RMSE%. The uniform anisotropic FE model explained 53-74% of the measured stiffness variance, with RMSE% ranging from 12.4 to 245.3%. The models which accounted for spatial variation of trabecular bone anisotropy predicted 76-79% of the variance in stiffness with RMSE% being 11.2-11.5%. Of the 16 evaluated finite element models in this study, the combination of Synder and Schneider (for cortical bone) and Cowin's fabric-elasticity equations (for trabecular bone) best predicted local subchondral bone stiffness. Copyright © 2017 Elsevier Ltd. All rights reserved.

Time dependent loss of trabecular bone in human tibial plateau fractures.

PubMed

Solomon, Lucian Bogdan; Kitchen, David; Anderson, Paul Hamill; Yang, Dongqing; Starczak, Yolandi; Kogawa, Masakazu; Perilli, Egon; Smitham, Peter Jonathan; Rickman, Mark Sean; Thewlis, Dominic; Atkins, Gerald James

2018-05-22

We investigated if time between injury and surgery affects cancellous bone properties in patients suffering tibial plateau fractures (TPF), in terms of structural integrity and gene expression controlling bone loss. A cohort of 29 TPF, operated 1-17 days post-injury, had biopsies from the fracture and an equivalent contralateral limb site, at surgery. Samples were assessed using micro-computed tomography and real-time RT-PCR analysis for the expression of genes known to be involved in bone remodeling and fracture healing. Significant decreases in the injured vs control side were observed for bone volume fraction (BV/TV, -13.5 ± 6.0%, p = 0.011), trabecular number (Tb.N, -10.5 ± 5.9%, p = 0.041) and trabecular thickness (Tb.Th, -4.6 ± 2.5%, p = 0.033). Changes in these parameters were more evident in patients operated 5-17 days post-injury, compared to those operated in the first 4 days post injury. A significant negative association was found between Tb.Th (r = -0.54, p < 0.01) and BV/TV (r = -0.39, p < 0.05) in relation to time post-injury in the injured limb. Both BV/TV and Tb.Th were negatively associated with expression of key molecular markers of bone resorption, CTSK, ACP5 and the ratio of RANKL:OPG mRNA. These structure/gene expression relationships did not exist in the contralateral tibial plateau of these patients. This study demonstrated that there is a significant early time-dependent bone loss in the proximal tibia after TPF. This bone loss was significantly associated with altered expression of genes typically involved in the process of osteoclastic bone resorption but possibly also by osteocytes. The mechanism of early bone loss in such fractures should be a subject of further investigation. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

The Eye Drop Preservative Benzalkonium Chloride Potently Induces Mitochondrial Dysfunction and Preferentially Affects LHON Mutant Cells.

PubMed

Datta, Sandipan; Baudouin, Christophe; Brignole-Baudouin, Francoise; Denoyer, Alexandre; Cortopassi, Gino A

2017-04-01

Benzalkonium chloride (BAK) is the most commonly used eye drop preservative. Benzalkonium chloride has been associated with toxic effects such as "dry eye" and trabecular meshwork degeneration, but the underlying biochemical mechanism of ocular toxicity by BAK is unclear. In this study, we propose a mechanistic basis for BAK's adverse effects. Mitochondrial O2 consumption rates of human corneal epithelial primary cells (HCEP), osteosarcoma cybrid cells carrying healthy (control) or Leber hereditary optic neuropathy (LHON) mutant mtDNA [11778(G>A)], were measured before and after acute treatment with BAK. Mitochondrial adenosine triphosphate (ATP) synthesis and cell viability were also measured in the BAK-treated control: LHON mutant and human-derived trabecular meshwork cells (HTM3). Benzalkonium chloride inhibited mitochondrial ATP (IC50, 5.3 μM) and O2 consumption (IC50, 10.9 μM) in a concentration-dependent manner, by directly targeting mitochondrial complex I. At its pharmaceutical concentrations (107-667 μM), BAK inhibited mitochondrial function >90%. In addition, BAK elicited concentration-dependent cytotoxicity to cybrid cells (IC50, 22.8 μM) and induced apoptosis in HTM3 cells at similar concentrations. Furthermore, we show that BAK directly inhibits mitochondrial O2 consumption in HCEP cells (IC50, 3.8 μM) at 50-fold lower concentrations than used in eye drops, and that cells bearing mitochondrial blindness (LHON) mutations are further sensitized to BAK's mitotoxic effect. Benzalkonium chloride inhibits mitochondria of human corneal epithelial cells and cells bearing LHON mutations at pharmacologically relevant concentrations, and we suggest this is the basis of BAK's ocular toxicity. Prescribing BAK-containing eye drops should be avoided in patients with mitochondrial deficiency, including LHON patients, LHON carriers, and possibly primary open-angle glaucoma patients.

The Eye Drop Preservative Benzalkonium Chloride Potently Induces Mitochondrial Dysfunction and Preferentially Affects LHON Mutant Cells

PubMed Central

Datta, Sandipan; Baudouin, Christophe; Brignole-Baudouin, Francoise; Denoyer, Alexandre; Cortopassi, Gino A.

2017-01-01

Purpose Benzalkonium chloride (BAK) is the most commonly used eye drop preservative. Benzalkonium chloride has been associated with toxic effects such as “dry eye” and trabecular meshwork degeneration, but the underlying biochemical mechanism of ocular toxicity by BAK is unclear. In this study, we propose a mechanistic basis for BAK's adverse effects. Method Mitochondrial O2 consumption rates of human corneal epithelial primary cells (HCEP), osteosarcoma cybrid cells carrying healthy (control) or Leber hereditary optic neuropathy (LHON) mutant mtDNA [11778(G>A)], were measured before and after acute treatment with BAK. Mitochondrial adenosine triphosphate (ATP) synthesis and cell viability were also measured in the BAK-treated control: LHON mutant and human-derived trabecular meshwork cells (HTM3). Results Benzalkonium chloride inhibited mitochondrial ATP (IC50, 5.3 μM) and O2 consumption (IC50, 10.9 μM) in a concentration-dependent manner, by directly targeting mitochondrial complex I. At its pharmaceutical concentrations (107–667 μM), BAK inhibited mitochondrial function >90%. In addition, BAK elicited concentration-dependent cytotoxicity to cybrid cells (IC50, 22.8 μM) and induced apoptosis in HTM3 cells at similar concentrations. Furthermore, we show that BAK directly inhibits mitochondrial O2 consumption in HCEP cells (IC50, 3.8 μM) at 50-fold lower concentrations than used in eye drops, and that cells bearing mitochondrial blindness (LHON) mutations are further sensitized to BAK's mitotoxic effect. Conclusions Benzalkonium chloride inhibits mitochondria of human corneal epithelial cells and cells bearing LHON mutations at pharmacologically relevant concentrations, and we suggest this is the basis of BAK's ocular toxicity. Prescribing BAK-containing eye drops should be avoided in patients with mitochondrial deficiency, including LHON patients, LHON carriers, and possibly primary open-angle glaucoma patients. PMID:28444329

Micro-scale finite element modeling of ultrasound propagation in aluminum trabecular bone-mimicking phantoms: A comparison between numerical simulation and experimental results.

PubMed

Vafaeian, B; Le, L H; Tran, T N H T; El-Rich, M; El-Bialy, T; Adeeb, S

2016-05-01

The present study investigated the accuracy of micro-scale finite element modeling for simulating broadband ultrasound propagation in water-saturated trabecular bone-mimicking phantoms. To this end, five commercially manufactured aluminum foam samples as trabecular bone-mimicking phantoms were utilized for ultrasonic immersion through-transmission experiments. Based on micro-computed tomography images of the same physical samples, three-dimensional high-resolution computational samples were generated to be implemented in the micro-scale finite element models. The finite element models employed the standard Galerkin finite element method (FEM) in time domain to simulate the ultrasonic experiments. The numerical simulations did not include energy dissipative mechanisms of ultrasonic attenuation; however, they expectedly simulated reflection, refraction, scattering, and wave mode conversion. The accuracy of the finite element simulations were evaluated by comparing the simulated ultrasonic attenuation and velocity with the experimental data. The maximum and the average relative errors between the experimental and simulated attenuation coefficients in the frequency range of 0.6-1.4 MHz were 17% and 6% respectively. Moreover, the simulations closely predicted the time-of-flight based velocities and the phase velocities of ultrasound with maximum relative errors of 20 m/s and 11 m/s respectively. The results of this study strongly suggest that micro-scale finite element modeling can effectively simulate broadband ultrasound propagation in water-saturated trabecular bone-mimicking structures. Copyright © 2016 Elsevier B.V. All rights reserved.

[Radiographic appraisal between metal and bone interosculate backfill after total hip arthroplasty with trabecular metal cup].

PubMed

Li, Wei; Zhou, Yi-Xin; Wu, Jian; Xu, Hui; Ji, Song-Jie

2009-02-15

To evaluate the bone refilling in the interface between the trabecular metal (TM) acetabular shell and the bone surface according to consecutive X film measuring after surgery. From July 2006 to July 2007, 35 patients (40 hips) accepted total hip replacement using trabecular metal monoblock acetabular cup system (TM). The cup was made of a ellipse shaped press fit Tantalum shell and high cross-linked PE liner (Longevity) with 28 mm inner diameter. The patients demography was: 16 male (20 hips), 19 female (20 hips), 5 bilateral hip replacements, age from 41 - 71 (mean 53), including 18 avascular necrosis hips, 16 osteoarthritis hips (including those secondary to a dysplasia hip), 4 avascular necrosis hips after femoral neck fracture, 2 Ankylosis Spondylitis. All the 40 total hip replacements used posterior approach, using hemispherical acetabular reamer and 2 mm press fit of final metal shell without screw fixation. The consecutive X film was taken at the end time of surgery and 2, 6, 12, 24 weeks, and 12 months. The clinical results was evaluate according to Harris scoring system, and the standard pelvis AP X film was measured at the interface between metal shell and the acetabular bone surface, witch was divided into five regions (A, B, C, D, E). Totally 32 patients (37 hips) were followed with average 8.7 months (7 - 12 months). The Harris before surgery was 50.5 (32 - 85), promoted to 91.0 (72 - 100), including 29 excellent, 6 good, 2 fair, and the total excellent and good rate was 94.6%. Complications include 4 patients leg length discrepancy from 1 - 2 cm, 3 patients moderate thigh pain and released after conservative therapy. No infection and dislocation was found. Twenty-one patients (23 hips) were found lucent line at the bone-metal interface from 1 - 5 mm, most common in B region and BC boundary than C, D, and CD boundary. All the patients followed was found the lucent line disappeared and refilled with bone at X film 24 weeks after surgery, however, no

The effective elastic properties of human trabecular bone may be approximated using micro-finite element analyses of embedded volume elements.

PubMed

Daszkiewicz, Karol; Maquer, Ghislain; Zysset, Philippe K

2017-06-01

Boundary conditions (BCs) and sample size affect the measured elastic properties of cancellous bone. Samples too small to be representative appear stiffer under kinematic uniform BCs (KUBCs) than under periodicity-compatible mixed uniform BCs (PMUBCs). To avoid those effects, we propose to determine the effective properties of trabecular bone using an embedded configuration. Cubic samples of various sizes (2.63, 5.29, 7.96, 10.58 and 15.87 mm) were cropped from [Formula: see text] scans of femoral heads and vertebral bodies. They were converted into [Formula: see text] models and their stiffness tensor was established via six uniaxial and shear load cases. PMUBCs- and KUBCs-based tensors were determined for each sample. "In situ" stiffness tensors were also evaluated for the embedded configuration, i.e. when the loads were transmitted to the samples via a layer of trabecular bone. The Zysset-Curnier model accounting for bone volume fraction and fabric anisotropy was fitted to those stiffness tensors, and model parameters [Formula: see text] (Poisson's ratio) [Formula: see text] and [Formula: see text] (elastic and shear moduli) were compared between sizes. BCs and sample size had little impact on [Formula: see text]. However, KUBCs- and PMUBCs-based [Formula: see text] and [Formula: see text], respectively, decreased and increased with growing size, though convergence was not reached even for our largest samples. Both BCs produced upper and lower bounds for the in situ values that were almost constant across samples dimensions, thus appearing as an approximation of the effective properties. PMUBCs seem also appropriate for mimicking the trabecular core, but they still underestimate its elastic properties (especially in shear) even for nearly orthotropic samples.

Use of proton pump inhibitors is associated with lower trabecular bone density in older individuals.

PubMed

Maggio, Marcello; Lauretani, Fulvio; Ceda, Gian Paolo; De Vita, Francesca; Bondi, Giuliana; Corsonello, Andrea; Cattabiani, Chiara; Lattanzio, Fabrizia; Ruggiero, Carmelinda; Nouvenne, Antonio; Meschi, Tiziana; Bandinelli, Stefania; Ferrucci, Luigi

2013-12-01

Proton pump inhibitors (PPIs) are highly effective in the treatment of upper gastrointestinal acid-related conditions and are fast becoming one of the most frequently prescribed treatments in adult or older persons. Recent data show that long-term use of PPIs in older subjects is associated with important undesirable effects, including a higher risk of osteoporotic fractures. The mechanisms of this association are unclear and the relationship between the use of PPIs and parameters of bone mass and geometry has never been fully explored. This study investigates the relationship between the chronic use of PPIs and the parameters of bone mass (cortical and trabecular bone mineral density - vBMDc and vBMDt) and bone geometry (cortical and trabecular cross sectional area - tCSA and cCSA) in older individuals. The study population consisted of 1038 subjects (452 men and 586 women) 65years or older, selected from the InCHIANTI study, with complete information on computerized tomography performed at tibial level (pQCT) and on medications. Participants were classified as PPI users and nonusers based on self-report of PPI use over the last 15days, with PPI users (36 subjects, 14 men and 22 women) making up 3.4% of the study population (mean age 75.7±7.4years). The relationship between use of PPIs and pQCT bone parameters was tested by multivariate linear regression analysis adjusted for age, sex and several clinical factors and/or statistically confounding variables identified by partial correlation coefficient and Spearman partial rank order correlation coefficients, as appropriate (age, sex, BMI, caloric intake, IGF-1, IL-6, calcium, estradiol, bioavailable testosterone, vitamin D, parathyroid hormone, cross-sectional muscle area, and level of physical activity). PPI users showed age- and sex-adjusted lower vBMDt than nonusers (180.5±54.8 vs. 207.9±59.4, p=0.001). The inverse association between PPI use and vBMDt remained almost unchanged after adjustment for multiple

Trabecular bone score (TBS) as a new complementary approach for osteoporosis evaluation in clinical practice.

PubMed

Harvey, N C; Glüer, C C; Binkley, N; McCloskey, E V; Brandi, M-L; Cooper, C; Kendler, D; Lamy, O; Laslop, A; Camargos, B M; Reginster, J-Y; Rizzoli, R; Kanis, J A

2015-09-01

Trabecular bone score (TBS) is a recently-developed analytical tool that performs novel grey-level texture measurements on lumbar spine dual X-ray absorptiometry (DXA) images, and thereby captures information relating to trabecular microarchitecture. In order for TBS to usefully add to bone mineral density (BMD) and clinical risk factors in osteoporosis risk stratification, it must be independently associated with fracture risk, readily obtainable, and ideally, present a risk which is amenable to osteoporosis treatment. This paper summarizes a review of the scientific literature performed by a Working Group of the European Society for Clinical and Economic Aspects of Osteoporosis and Osteoarthritis. Low TBS is consistently associated with an increase in both prevalent and incident fractures that is partly independent of both clinical risk factors and areal BMD (aBMD) at the lumbar spine and proximal femur. More recently, TBS has been shown to have predictive value for fracture independent of fracture probabilities using the FRAX® algorithm. Although TBS changes with osteoporosis treatment, the magnitude is less than that of aBMD of the spine, and it is not clear how change in TBS relates to fracture risk reduction. TBS may also have a role in the assessment of fracture risk in some causes of secondary osteoporosis (e.g., diabetes, hyperparathyroidism and glucocorticoid-induced osteoporosis). In conclusion, there is a role for TBS in fracture risk assessment in combination with both aBMD and FRAX. Copyright © 2015 Elsevier Inc. All rights reserved.

Trabecular bone score (TBS) as a new complementary approach for osteoporosis evaluation in clinical practice

PubMed Central

Harvey, N.C.; Glüer, C.C.; Binkley, N.; McCloskey, E.V.; Brandi, M-L.; Cooper, C.; Kendler, D.; Lamy, O.; Laslop, A.; Camargos, B.M.; Reginster, J-Y.; Rizzoli, R.; Kanis, J.A.

2015-01-01

Trabecular bone score (TBS) is a recently-developed analytical tool that performs novel grey-level texture measurements on lumbar spine dual X-ray absorptiometry (DXA) images, and thereby captures information relating to trabecular microarchitecture. In order for TBS to usefully add to bone mineral density (BMD) and clinical risk factors in osteoporosis risk stratification, it must be independently associated with fracture risk, readily obtainable, and ideally, present a risk which is amenable to osteoporosis treatment. This paper summarizes a review of the scientific literature performed by a Working Group of the European Society for Clinical and Economic Aspects of Osteoporosis and Osteoarthritis. Low TBS is consistently associated with an increase in both prevalent and incident fractures that is partly independent of both clinical risk factors and areal BMD (aBMD) at the lumbar spine and proximal femur. More recently, TBS has been shown to have predictive value for fracture independent of fracture probabilities using the FRAX® algorithm. Although TBS changes with osteoporosis treatment, the magnitude is less than that of aBMD of the spine, and it is not clear how change in TBS relates to fracture risk reduction. TBS may also have a role in the assessment of fracture risk in some causes of secondary osteoporosis (e.g. diabetes, hyperparathyroidism and glucocorticoid-induced osteoporosis). In conclusion, there is a role for TBS in fracture risk assessment in combination with both aBMD and FRAX. PMID:25988660

Characterization of trabecular bone using the backscattered spectral centroid shift.

PubMed

Wear, Keith A

2003-04-01

Ultrasonic attenuation in bone in vivo is generally measured using a through-transmission method at the calcaneus. Although attenuation in calcaneus has been demonstrated to be a useful predictor for osteoporotic fracture risk, measurements at other clinically important sites, such as hip and spine, could potentially contain additional useful diagnostic information. Through-transmission measurements may not be feasible at these sites due to complex bone shapes and the increased amount of intervening soft tissue. Centroid shift from the backscattered signal is an index of attenuation slope and has been used previously to characterize soft tissues. In this paper, centroid shift from signals backscattered from 30 trabecular bone samples in vitro were measured. Attenuation slope also was measured using a through-transmission method. The correlation coefficient between centroid shift and attenuation slope was -0.71. The 95% confidence interval was (-0.86, -0.47). These results suggest that the backscattered spectral centroid shift may contain useful diagnostic information potentially applicable to hip and spine.

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

NASA Technical Reports Server (NTRS)

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

2014-01-01

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

Short-term survival of the trabecular metal cup is similar to that of standard cups used in acetabular revision surgery.

PubMed

Mohaddes, Maziar; Rolfson, Ola; Kärrholm, Johan

2015-02-01

The use of trabecular metal (TM) cups in revision surgery has increased worldwide during the last decade. Since the introduction of the TM cup in Sweden in 2006, this design has gradually replaced other uncemented designs used in Sweden. According to data from the Swedish Hip Arthroplasty Register (SHAR) in 2012, one-third of all uncemented first-time cup revisions were performed using a TM cup. We compared the risk of reoperation and re-revision for TM cups and the 2 other most frequently used cup designs in acetabular revisions reported to the SHAR. The hypothesis was that the performance of TM cups is as good as that of established designs in the short term. The study population consisted of 2,384 patients who underwent 2,460 revisions during the period 2006 through 2012. The most commonly used cup designs were the press-fit porous-coated cup (n = 870), the trabecular metal cup (n = 805), and the cemented all-polyethylene cup (n = 785). 54% of the patients were female, and the median age at index revision was 72 (19-95) years. Reoperation was defined as a second surgical intervention, and re-revision-meaning exchange or removal of the cup-was used as endpoint. The mean follow-up time was 3.3 (0-7) years. There were 215 reoperations, 132 of which were re-revisions. The unadjusted and adjusted risk of reoperation or re-revision was not significantly different for the TM cup and the other 2 cup designs. Our data support continued use of TM cups in acetabular revisions. Further follow-up is necessary to determine whether trabecular metal cups can reduce the re-revision rate in the long term, compared to the less costly porous press-fit and cemented designs.

Loss of the hematopoietic stem cell factor GATA2 in the osteogenic lineage impairs trabecularization and mechanical strength of bone.

PubMed

Tolkachov, Alexander; Fischer, Cornelius; Ambrosi, Thomas H; Bothe, Melissa; Han, Chung-Ting; Muenzner, Matthias; Mathia, Susanne; Salminen, Marjo; Seifert, Georg; Thiele, Mario; Duda, Georg N; Meijsing, Sebastiaan H; Sauer, Sascha; Schulz, Tim J; Schupp, Michael

2018-03-26

The transcription factor GATA2 is required for expansion and differentiation of hematopoietic stem cells (HSCs). In mesenchymal stem cells (MSCs) GATA2 blocks adipogenesis, but its biological relevance and underlying genomic events are unknown. We report a dual function of GATA2 in bone homeostasis. GATA2 in MSCs binds near genes involved in skeletal system development and co-localizes with motifs for FOX and HOX transcription factors, known regulators of skeletal development. Ectopic GATA2 blocks osteoblastogenesis by interfering with SMAD1/5/8 activation. MSC-specific deletion of GATA2 in mice increases numbers and differentiation capacity of bone-derived precursors, resulting in elevated bone formation. Surprisingly, MSC-specific GATA2 deficiency impairs trabecularization and mechanical strength of bone, involving reduced MSC expression of the osteoclast inhibitor osteoprotegerin and increased osteoclast numbers. Thus, GATA2 affects bone turnover via MSC-autonomous and indirect effects. By regulating bone trabecularization, GATA2 expression in the osteogenic lineage may contribute to the anatomical and cellular microenvironment of the HSC niche required for hematopoiesis. Copyright © 2018 American Society for Microbiology.

Endogenous Production of Extracellular Adenosine by Trabecular Meshwork Cells: Potential Role in Outflow Regulation

PubMed Central

Wu, Jing; Li, Guorong; Luna, Coralia; Spasojevic, Ivan; Epstein, David L.; Gonzalez, Pedro

2012-01-01

Purpose. To investigate the mechanisms for endogenous production of extracellular adenosine in trabecular meshwork (TM) cells and evaluate its physiological relevance to the regulation of aqueous humor outflow facility. Methods. Extra-cellular levels of adenosine monophosphate (AMP) and adenosine in porcine trabecular meshwork (PTM) cells treated with adenosine triphosphate (ATP), AMP, cAMP or forskolin with or without specific inhibitors of phosphodiesterases (IBMX) and CD73 (AMPCP) were determined by high-pressure liquid chromatography fluorometry. Extracellular adenosine was also evaluated in cell cultures subjected to cyclic mechanical stress (CMS) (20% stretching; 1 Hz) and after disruption of lipid rafts with methyl-β-cyclodextrin. Expression of CD39 and CD73 in porcine TM cells and tissue were examined by Q-PCR and Western blot. The effect of inhibition of CD73 on outflow facility was evaluated in perfused living mouse eyes. Results. PTM cells generated extracellular adenosine from extracellular ATP and AMP but not from extracellular cAMP. Increased intracellular cAMP mediated by forskolin led to a significant increase in extracellular adenosine production that was not prevented by IBMX. Inhibition of CD73 resulted, in all cases, in a significant decrease in extracellular adenosine. CMS induced a significant activation of extracellular adenosine production. Inhibition of CD73 activity with AMPCP in living mouse eyes resulted in a significant decrease in outflow facility. Conclusions. These results support the concept that the extracellular adenosine pathway might play an important role in the homeostatic regulation of outflow resistance in the TM, and suggest a novel mechanism by which pathologic alteration of the TM, such as increased tissue rigidity, could lead to abnormal elevation of IOP in glaucoma. PMID:22997289

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gotman, Irena, E-mail: gotman@technion.ac.il; Gutmanas, Elazar Y., E-mail: gutmanas@technion.ac.il; National Research Tomsk Polytechnic University, Tomsk, 634050

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

Hybrid Food Preservation Program Improves Food Preservation and Food Safety Knowledge

ERIC Educational Resources Information Center

Francis, Sarah L.

2014-01-01

The growing trend in home food preservation raises concerns about whether the resulting food products will be safe to eat. The increased public demand for food preservation information led to the development of the comprehensive food preservation program, Preserve the Taste of Summer (PTTS). PTTS is a comprehensive hybrid food preservation program…

Preserve the (intraocular) environment: the importance of maintaining normal oxygen gradients in the eye.

PubMed

Beebe, David C; Shui, Ying-Bo; Siegfried, Carla J; Holekamp, Nancy M; Bai, Fang

2014-05-01

Oxygen levels in the eye are generally low and tightly regulated. Oxygen enters the eye largely by diffusion from retinal arterioles and through the cornea. In intact eyes, oxygen from the retinal arterioles diffuses into the vitreous body. There is a decreasing oxygen gradient from the retina to the lens, established by oxygen consumption by ascorbate in the vitreous fluid and lens metabolism. Age-related degeneration of the vitreous body or removal during vitrectomy exposes the posterior of the lens to increased oxygen, causing nuclear sclerotic cataracts. Lowering oxygen in the vitreous, as occurs in patients with ischemic diabetic retinopathy, protects against cataracts after vitrectomy. Vitrectomy and cataract surgery increase oxygen levels at the trabecular meshwork and with it the risk of open angle glaucoma. Two additional risk factors for glaucoma, African heritage and having a thinner cornea, are also associated with increased oxygen in the anterior chamber angle. Preservation of the vitreous body and the lens, two important oxygen consumers, would protect against nuclear sclerotic cataracts and open angle glaucoma. Delaying removal of the lens for as long as possible after vitrectomy would be an important step in delaying ocular hypertension and glaucoma progression.

Using Non-linear Homogenization to Improve the Performance of Macroscopic Damage Models of Trabecular Bone.

PubMed

Levrero-Florencio, Francesc; Pankaj, Pankaj

2018-01-01

Realistic macro-level finite element simulations of the mechanical behavior of trabecular bone, a cellular anisotropic material, require a suitable constitutive model; a model that incorporates the mechanical response of bone for complex loading scenarios and includes post-elastic phenomena, such as plasticity (permanent deformations) and damage (permanent stiffness reduction), which bone is likely to experience. Some such models have been developed by conducting homogenization-based multiscale finite element simulations on bone micro-structure. While homogenization has been fairly successful in the elastic regime and, to some extent, in modeling the macroscopic plastic response, it has remained a challenge with respect to modeling damage. This study uses a homogenization scheme to upscale the damage behavior from the tissue level (microscale) to the organ level (macroscale) and assesses the suitability of different damage constitutive laws. Ten cubic specimens were each subjected to 21 strain-controlled load cases for a small range of macroscopic post-elastic strains. Isotropic and anisotropic criteria were considered, density and fabric relationships were used in the formulation of the damage law, and a combined isotropic/anisotropic law with tension/compression asymmetry was formulated, based on the homogenized results, as a possible alternative to the currently used single scalar damage criterion. This computational study enhances the current knowledge on the macroscopic damage behavior of trabecular bone. By developing relationships of damage progression with bone's micro-architectural indices (density and fabric) the study also provides an aid for the creation of more precise macroscale continuum models, which are likely to improve clinical predictions.

Bisphosphonates Improve Trabecular Bone Mass and Normalize Cortical Thickness in Ovariectomized, Osteoblast Connexin43 Deficient Mice

PubMed Central

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

2012-01-01

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 (20µg/kg) or alendronate (40µg/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. PMID:22750450

Displacement of dental implants in trabecular bone under a static lateral load in fresh bovine bone.

PubMed

Engelke, Wilfried; Müller, Alois; Decco, Oscar A; Rau, María J; Cura, Andrea C; Ruscio, Mara L; Knösel, Michael

2013-04-01

The study aims to provide objective data for the displacement of titanium screw implants in trabecular bone specimens. One hundred Semados implants (Bego, Bremen, Germany) were inserted in bovine type IV bone specimens. All implants had a diameter of 3.75 mm; 50 implants had a length of 8.5 mm and 50 implants had a length of 15 mm. Insertion torque was determined at intervals of 10, 20, and 30 Ncm. Implants were loaded horizontally with 10, 20, and 30 N for 2 seconds. An indicator strip was attached to the implant abutment to allow direct observation of implant movement relative to the bone surface. Horizontal displacement was assessed with an accuracy of measurement of 10 µm. Seven implants got lost by visible loosening. Degree of displacement was subject to evaluation with all others. Those implants showed a mean displacement of 59 µm for 10 N (n = 100), 173 µm for 20 N (n = 99), and 211 µm for 30 N (n = 93). The mean displacement of 15-mm implants (16, 37, 51 µm) was significantly lower compared with 8.5-mm implants (103, 311, 396 µm) corresponding to 10, 20, and 30 N as lateral loads. Displacement of screw implants in trabecular bone can be detected and visualized using commercially available endoscopes with a high magnification. A lateral load of 20 N indicates a mean displacement of over 100 µm and therefore results in a critical displacement. © 2011 Wiley Periodicals, Inc.

Changes in Ocular Surface Characteristics after Switching from Benzalkonium Chloride-Preserved Latanoprost to Preservative-Free Tafluprost or Benzalkonium Chloride-Preserved Tafluprost.

PubMed

Tokuda, Naoto; Kitaoka, Yasushi; Matsuzawa, Akiko; Tsukamoto, Ayaka; Sase, Kana; Sakae, Shinsuke; Takagi, Hitoshi

2017-01-01

The aim of the present study was to examine the effects of switching from Latanoprost ophthalmic solution containing a preservative to preservative-free Tafluprost ophthalmic solution or Tafluprost containing a preservative on ocular surfaces. Forty patients (40 eyes) with glaucoma (mean age: 62.0 ± 10.9 years) using Latanoprost with preservative for six months or longer were assigned either to a Tafluprost-containing-preservative group (20 eyes) or preservative-free-Tafluprost group (20 eyes). The intraocular pressure, corneal epithelial barrier function (fluorescein uptake concentration with fluorophotometer FL-500), superficial punctate keratopathy (AD classification), and tear film breakup time (TBUT) were assessed before switching and at 12 weeks after switching. No significant differences in intraocular pressure were noted after switching in either group. Corneal epithelial barrier function was improved significantly after switching in both the Tafluprost-containing-preservative and the preservative-free-Tafluprost groups. There were no significant differences in AD scores after switching in the Tafluprost-containing-preservative group, but significant improvements were noted in the preservative-free-Tafluprost group. No significant differences in TBUT were noted in the Tafluprost-containing-preservative or preservative-free-Tafluprost groups after switching. After switching from preservative Latanoprost to Tafluprost containing-preservative or preservative-free Tafluprost, corneal epithelial barrier function was improved while the intraocular pressure reduction was retained.

Electron absorbed fractions of energy and S-values in an adult human skeleton based on µCT images of trabecular bone

NASA Astrophysics Data System (ADS)

Kramer, R.; Richardson, R. B.; Cassola, V. F.; Vieira, J. W.; Khoury, H. J.; Lira, C. A. B. de O.; Robson Brown, K.

2011-03-01

When the human body is exposed to ionizing radiation, among the soft tissues at risk are the active marrow (AM) and the bone endosteum (BE) located in tiny, irregular cavities of trabecular bone. Determination of absorbed fractions (AFs) of energy or absorbed dose in the AM and the BE represent one of the major challenges of dosimetry. Recently, at the Department of Nuclear Energy at the Federal University of Pernambuco, a skeletal dosimetry method based on µCT images of trabecular bone introduced into the spongiosa voxels of human phantoms has been developed and applied mainly to external exposure to photons. This study uses the same method to calculate AFs of energy and S-values (absorbed dose per unit activity) for electron-emitting radionuclides known to concentrate in skeletal tissues. The modelling of the skeletal tissue regions follows ICRP110, which defines the BE as a 50 µm thick sub-region of marrow next to the bone surfaces. The paper presents mono-energetic AFs for the AM and the BE for eight different skeletal regions for electron source energies between 1 keV and 10 MeV. The S-values are given for the beta emitters 14C, 59Fe, 131I, 89Sr, 32P and 90Y. Comparisons with results from other investigations showed good agreement provided that differences between methodologies and trabecular bone volume fractions were properly taken into account. Additionally, a comparison was made between specific AFs of energy in the BE calculated for the actual 50 µm endosteum and the previously recommended 10 µm endosteum. The increase in endosteum thickness leads to a decrease of the endosteum absorbed dose by up to 3.7 fold when bone is the source region, while absorbed dose increases by ~20% when the beta emitters are in marrow.

Stem Cells in the Trabecular Meshwork for Regulating Intraocular Pressure.

PubMed

Yun, Hongmin; Zhou, Yi; Wills, Andrew; Du, Yiqin

2016-06-01

Intraocular pressure (IOP) is still the main treatment target for glaucoma. Outflow resistance mainly exists at the trabecular meshwork (TM) outflow pathway, which is responsible for IOP regulation. Changes of TM cellularity and TM extracellular matrix turnover may play important roles in IOP regulation. In this article, we review basic anatomy and physiology of the outflow pathway and TM stem cell characteristics regarding the location, isolation, identification and function. TM stem cells are localized at the insert region of the TM and are label-retaining in vivo. They can be isolated by side-population cell sorting, cloning culture, or sphere culture. TM stem cells are multipotent with the ability to home to the TM region and differentiate into TM cells in vivo. Other stem cell types, such as adipose-derived stem cells, mesenchymal stem cells and induced pluripotent stem cells have been discovered for TM cell differentiation and TM regeneration. We also review glaucomatous animal models, which are suitable to study stem cell-based therapies for TM regeneration.

Stem Cells in the Trabecular Meshwork for Regulating Intraocular Pressure

PubMed Central

Yun, Hongmin; Zhou, Yi; Wills, Andrew

2016-01-01

Abstract Intraocular pressure (IOP) is still the main treatment target for glaucoma. Outflow resistance mainly exists at the trabecular meshwork (TM) outflow pathway, which is responsible for IOP regulation. Changes of TM cellularity and TM extracellular matrix turnover may play important roles in IOP regulation. In this article, we review basic anatomy and physiology of the outflow pathway and TM stem cell characteristics regarding the location, isolation, identification and function. TM stem cells are localized at the insert region of the TM and are label-retaining in vivo. They can be isolated by side-population cell sorting, cloning culture, or sphere culture. TM stem cells are multipotent with the ability to home to the TM region and differentiate into TM cells in vivo. Other stem cell types, such as adipose-derived stem cells, mesenchymal stem cells and induced pluripotent stem cells have been discovered for TM cell differentiation and TM regeneration. We also review glaucomatous animal models, which are suitable to study stem cell-based therapies for TM regeneration. PMID:27183473

TECHNIQUES AND OUTCOMES OF MINIMALLY-INVASIVE TRABECULAR ABLATION AND BYPASS SURGERY

PubMed Central

Kaplowitz, Kevin; Schuman, Joel S.; Loewen, Nils A.

2014-01-01

Minimally invasive glaucoma surgeries (MIGS) can improve the conventional, pressure dependent outflow by bypassing or ablating the trabecular meshwork or create alternative drainage routes into the suprachoroidal or subconjunctival space. They have a highly favorable risk profile compared to penetrating surgeries and lower intraocular pressure with variable efficacy that may depend on the extent of outflow segments accessed. Since they are highly standardized procedures that use clear corneal incisions, they can elegantly be combined with cataract and refractive procedures to improve vision in the same session. There is a growing need for surgeons to become proficient in MIGS to address the increasing prevalence of glaucoma and cataracts in a well-informed, aging population. Techniques of visualization and instrumentation in an anatomically highly confined space with semi-transparent tissues are fundamentally different from other anterior segment surgeries and present even experienced surgeons with a substantial learning curve. Here, we provide practical tips and review techniques and outcomes of TM bypass and ablation MIGS. PMID:24338085

Trabecular bone microarchitecture analysis, a way for an early detection of genetic dwarfism? Case study of a dwarf mother's offspring.

PubMed

Colombo, Antony; Hoogland, Menno; Coqueugniot, Hélène; Dutour, Olivier; Waters-Rist, Andrea

2018-03-01

A 66 year-old woman with a disproportionate dwarfism and who bore seven children was discovered at the Middenbeemster archaeological site (The Netherlands). Three are perinates and show no macroscopic or radiological evidence for a FGFR3 mutation causing hypo-or achondroplasia. This mutation induces dysfunction of the growth cartilage, leading to abnormalities in the development of trabecular bone. Because the mutation is autosomal dominant, these perinates have a 50% risk of having been affected. This study determines whether trabecular bone microarchitecture (TBMA) analysis is useful for detecting genetic dwarfism. Proximal metaphyses of humeri were μCT-scanned with a resolution of 7-12 μm. Three volumes of interest were segmented from each bone with TIVMI© software. The TBMA was quantified in BoneJ© using six parameters on which a multivariate analysis was then performed. Two of the Middenbeemster perinates show a quantitatively different TBMA organization. These results and the family's medical history suggest a diagnosis of genetic dwarfism for this two perinates. This study provides evidence to support the efficacy of μCT for diagnosing early-stage bone disease. Copyright © 2017 Elsevier Inc. All rights reserved.

Cellular Fibronectin Expression in Human Trabecular Meshwork and Induction by Transforming Growth Factor-β2

PubMed Central

Medina-Ortiz, Wanda E.; Belmares, Ricardo; Neubauer, Sandra; Wordinger, Robert J.; Clark, Abbot F.

2013-01-01

Purpose. Levels of TGF-β2 are higher in POAG aqueous humor, causing deposition of extracellular matrix (ECM) proteins, including fibronectin (FN), in the glaucomatous human trabecular meshwork (HTM) that may be responsible for elevated IOP. The purpose of this study was to identify the expression of cellular FN (cFN) isoforms (EDA and EDB) in HTM cells and tissues, and to determine whether TGF-β2 can induce cFN expression and fibril formation in cultured HTM cells. Methods. Expression of cFN mRNA isoforms and induction by recombinant TGF-β2 (5 ng/mL) were determined by quantitative RT-PCR. The TGF-β2 induction of EDA isoform protein expression and FN fibril formation were analyzed using Western immunoblots and immunocytochemistry (ICC), respectively. Immunohistochemistry (IHC) analysis was used to examine total FN and EDA isoform expression in normal (NTM) and glaucomatous (GTM) trabecular meshwork (TM) tissues. Results. Both cFN mRNA isoforms were expressed in cultured HTM cells and were induced by TGF-β2 after 2, 4, and 7 days (P < 0.05). Similarly, EDA isoform protein and fibril formation were increased after 4 and 7 days of TGF-β2 treatment. Finally, GTM tissues had significantly greater EDA isoform protein levels (1.7-fold, P < 0.05) compared to NTM tissues. Conclusions. This study demonstrated that cFN isoforms are expressed and induced in HTM cells by TGF-β2. Also, increased EDA isoform protein levels were seen in GTM tissues. Our findings suggest that induction of cFN isoform expression in the TM ECM may be a novel pathologic mechanism involved in the TM changes associated with glaucoma. PMID:24030464

Self-preserving cosmetics.

PubMed

Varvaresou, A; Papageorgiou, S; Tsirivas, E; Protopapa, E; Kintziou, H; Kefala, V; Demetzos, C

2009-06-01

Preservatives are added to products for two reasons: first, to prevent microbial spoilage and therefore to prolong the shelf life of the product; second, to protect the consumer from a potential infection. Although chemical preservatives prevent microbial growth, their safety is questioned by a growing segment of consumers. Therefore, there is a considerable interest in the development of preservative-free or self-preserving cosmetics. In these formulations traditional/chemical preservatives have been replaced by other cosmetic ingredients with antimicrobial properties that are not legislated as preservatives according to the Annex VI of the Commission Directive 76/768/EEC and the amending directives (2003/15/EC, 2007/17/EC and 2007/22/EC). 'Hurdle Technology', a technology that has been used for the control of product safety in the food industry since 1970s, has also been applied for the production of self-preserving cosmetics. 'Hurdle Technology' is a term used to describe the intelligent combination of different preservation factors or hurdles to deteriorate the growth of microorganisms. Adherence to current good manufacturing practice, appropriate packaging, careful choice of the form of the emulsion, low water activity and low or high pH values are significant variables for the control of microbial growth in cosmetic formulations. This paper describes the application of the basic principles of 'Hurdle Technology' in the production of self-preserving cosmetics. Multifunctional antimicrobial ingredients and plant-derived essential oils and extracts that are used as alternative or natural preservatives and are not listed in Annex VI of the Cosmetic Directive are also reported.

Direct biomechanical modeling of trabecular bone using a nonlinear manifold-based volumetric representation

NASA Astrophysics Data System (ADS)

Jin, Dakai; Lu, Jia; Zhang, Xiaoliu; Chen, Cheng; Bai, ErWei; Saha, Punam K.

2017-03-01

Osteoporosis is associated with increased fracture risk. Recent advancement in the area of in vivo imaging allows segmentation of trabecular bone (TB) microstructures, which is a known key determinant of bone strength and fracture risk. An accurate biomechanical modelling of TB micro-architecture provides a comprehensive summary measure of bone strength and fracture risk. In this paper, a new direct TB biomechanical modelling method using nonlinear manifold-based volumetric reconstruction of trabecular network is presented. It is accomplished in two sequential modules. The first module reconstructs a nonlinear manifold-based volumetric representation of TB networks from three-dimensional digital images. Specifically, it starts with the fuzzy digital segmentation of a TB network, and computes its surface and curve skeletons. An individual trabecula is identified as a topological segment in the curve skeleton. Using geometric analysis, smoothing and optimization techniques, the algorithm generates smooth, curved, and continuous representations of individual trabeculae glued at their junctions. Also, the method generates a geometrically consistent TB volume at junctions. In the second module, a direct computational biomechanical stress-strain analysis is applied on the reconstructed TB volume to predict mechanical measures. The accuracy of the method was examined using micro-CT imaging of cadaveric distal tibia specimens (N = 12). A high linear correlation (r = 0.95) between TB volume computed using the new manifold-modelling algorithm and that directly derived from the voxel-based micro-CT images was observed. Young's modulus (YM) was computed using direct mechanical analysis on the TB manifold-model over a cubical volume of interest (VOI), and its correlation with the YM, computed using micro-CT based conventional finite-element analysis over the same VOI, was examined. A moderate linear correlation (r = 0.77) was observed between the two YM measures. This

Age-related posterior ciliary muscle restriction - A link between trabecular meshwork and optic nerve head pathophysiology.

PubMed

Croft, Mary Ann; Lütjen-Drecoll, Elke; Kaufman, Paul L

2017-05-01

The ciliary muscle plays a major role in controlling both accommodation and outflow facility in primates. The ciliary muscle and the choroid functionally form an elastic network that extends from the trabecular meshwork all the way to the back of the eye and ultimately attaches to the elastic fiber ring that surrounds the optic nerve and to the lamina cribrosa through which the nerve passes. The ciliary muscle governs the accommodative movement of the elastic network. With age ciliary muscle mobility is restricted by progressively inelastic posterior attachments and the posterior restriction makes the contraction progressively isometric; placing increased tension on the optic nerve region. In addition, outflow facility also declines with age and limbal corneoscleral contour bows inward. Age-related loss in muscle movement and altered limbal corneoscleral contour could both compromise the basal function of the trabecular meshwork. Further, recent studies in non-human primates show that the central vitreous moves posteriorly all the way back to the optic nerve region, suggesting a fluid current and a pressure gradient toward the optic nerve. Thus, there may be pressure and tension spikes on the optic nerve region during accommodation and these pressure and tension spikes may increase with age. This constellation of events could be relevant to glaucomatous optic neuropathy. In summary, our hypothesis is that glaucoma and presbyopia may be literally linked to each other, via the choroid, and that damage to the optic nerve may be inflicted by accommodative intraocular pressure and choroidal tension "spikes", which may increase with age. Copyright © 2016 Elsevier Ltd. All rights reserved.

Trabecular micro-bypass stent implantation during small-incision cataract surgery for open-angle glaucoma or ocular hypertension: Long-term results.

PubMed

Neuhann, Tobias H

2015-12-01

To evaluate long-term safety and efficacy of iStent trabecular micro-bypass stent implantation during cataract surgery in patients with primary open-angle, pseudo-exfoliation glaucoma, ocular hypertension, or secondary or post-traumatic glaucoma. AaM Augenklinik am Marienplatz, Munich, Germany. Prospective, open-label, non-randomized study. Preoperative and postoperative evaluations included intra-ocular pressure (IOP), topical ocular hypotensive medication use, cup/disc ratio, corrected-distance visual acuity (CDVA), complications, and adverse events. A single trabecular micro-bypass stent was implanted through the same temporal, limbal incision used for cataract surgery via phacoemulsification in a consecutive series of 62 eyes of 43 patients. To date, a total of 41 eyes have been followed for 3 years postoperatively, whereas long-term postoperative follow-up on the remaining patients is ongoing. Mean preoperative IOP was 24.1 ± 6.9 mm Hg on a mean of 1.8 medications (±0.9). Analyses of eyes with no secondary surgical intervention showed mean IOP reduction to 14.8 ± 4.2 mm Hg at 12 months (n = 61), 14.5 ± 2.2 mm Hg at 24 months (n = 42), and 14.9 ± 2.3 mm Hg at 36 months (n = 39). Medications were eliminated in 74% of eyes at 36 months. Five eyes, 4 with previous glaucoma surgeries and 1 with pseudo-exfoliation syndrome, required additional glaucoma surgery after stent implantation. No intra-operative or postoperative complications typically seen with conventional glaucoma surgeries occurred after stent implantation. At 36 months, CDVA was 20/40 or better in 38 eyes (93%). Trabecular micro-bypass stent implantation during cataract surgery was safe and effective in patients with ocular hypertension or glaucoma as measured by a sustained reduction in IOP and medication use and an excellent safety profile through 3 years after surgery. Dr. Neuhann has no financial or proprietary interest in any material or method mentioned. Glaukos Corp. provided editorial

Local measurements of the diffusion constant in multiple scattering media: Application to human trabecular bone imaging

NASA Astrophysics Data System (ADS)

Aubry, Alexandre; Derode, Arnaud; Padilla, Frédéric

2008-03-01

We present local measurements of the diffusion constant for ultrasonic waves undergoing multiple scattering. The experimental setup uses a coherent array of programmable transducers. By achieving Gaussian beamforming at emission and reception, an array of virtual sources and receivers located in the near field is constructed. A matrix treatment is proposed to separate the incoherent intensity from the coherent backscattering peak. Local measurements of the diffusion constant D are then achieved. This technique is applied to a real case: a sample of human trabecular bone for which the ultrasonic characterization of multiple scattering is an issue.

Effects of Lewis lung carcinoma on trabecular microstructural changes in wild-type and plasminogen activator inhibitor-1 deficient mice fed a high-fat diet

USDA-ARS?s Scientific Manuscript database

Bone is a major target organ of metastasis. The present study investigated the effects of Lewis lung carcinoma (LLC) on trabecular microstructural changes, using tomographic analysis, in distal femur and lumbar 4 vertebra from LLC-bearing wild-type and plasminogen activator inhibitor-1 (PAI-1) defi...

Comparison of contamination rates between preserved and preservative-free fluoroquinolone eyedrops.

PubMed

Kim, Mo Sae; Kim, Hong Kyun; Kim, Joon Mo; Choi, Chul Young

2013-03-01

To evaluate the antimicrobial effectiveness of preservative-free fluoroquinolone products compared with benzalkonium chloride containing fluoroquinolones using the challenge test provided by the United States Pharmacopeia (USP) and the in-use test. 1. Challenge test: to compare the growth of microorganisms between different fluoroquinolone preparations, four test organisms, including Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans, and Aspergillus niger were chosen among five microorganisms listed by USP 2004. The inoculated products were sampled for microbial survivors at days 7, 14, and 28 following initial inoculation at room temperature. The number of surviving organisms were calculated as a Log10 reduction from the original inocula. 2. In-use test: a total of 100 bottles were collected after instillation of preservative-free fluoroquinolone eyedrops in volunteer patients after 1 week of use. The remaining fluid and tips of the bottles were cultured. Colonies on the plates were counted at the end of the incubation period. All microorganisms were identified by Gram staining and biochemical assays. 1. Challenge test: preservative-free gatifloxacin and levofloxacin demonstrated a lower log reduction against A. niger than preserved fluoroquinolones and preservative-free moxifloxacin at all time points. 2. In-use test: There was no contamination identified on plates inoculated by preservative-free quinolone bottles after 1 week of use in this study. Physicians should be aware of the lower antifungal preservative effectiveness of some preservative-free fluoroquinolone preparations than preserved ones.

Wood preservation

Treesearch

Kevin Archer; Stan Lebow

2006-01-01

Wood preservation can be interpreted to mean protection from fire, chemical degradation, mechanical wear, weathering, as well as biological attack. In this chapter, the term preservation is applied more restrictively to protection from biological hazards.

Direct trabecular meshwork imaging in porcine eyes through multiphoton gonioscopy.

PubMed

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

2013-03-01

The development of technologies to characterize the ocular aqueous outflow system (AOS) is important for the understanding of the pathophysiology of glaucoma. Multiphoton microscopy (MPM) offers the advantage of high-resolution, label-free imaging with intrinsic image contrast because the emitted signals result from the specific biomolecular content of the tissue. Previous attempts to use MPM to image the murine irido-corneal region directly through the sclera have suffered from degradation in image resolution due to scattering of the focused laser light. As a result, transscleral MPM has limited ability to observe fine structures in the AOS. In this work, the porcine irido-corneal angle was successfully imaged through the transparent cornea using a gonioscopic lens to circumvent the highly scattering scleral tissue. The resulting high-resolution images allowed the detailed structures in the trabecular meshwork (TM) to be observed. Multimodal imaging by two-photon autofluorescence and second harmonic generation allowed visualization of different features in the TM without labels and without disruption of the TM or surrounding tissues. MPM gonioscopy is a promising noninvasive imaging tool for high-resolution studies of the AOS, and research continues to explore the potential for future clinical applications in humans.

Direct trabecular meshwork imaging in porcine eyes through multiphoton gonioscopy

NASA Astrophysics Data System (ADS)

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

2013-03-01

The development of technologies to characterize the ocular aqueous outflow system (AOS) is important for the understanding of the pathophysiology of glaucoma. Multiphoton microscopy (MPM) offers the advantage of high-resolution, label-free imaging with intrinsic image contrast because the emitted signals result from the specific biomolecular content of the tissue. Previous attempts to use MPM to image the murine irido-corneal region directly through the sclera have suffered from degradation in image resolution due to scattering of the focused laser light. As a result, transscleral MPM has limited ability to observe fine structures in the AOS. In this work, the porcine irido-corneal angle was successfully imaged through the transparent cornea using a gonioscopic lens to circumvent the highly scattering scleral tissue. The resulting high-resolution images allowed the detailed structures in the trabecular meshwork (TM) to be observed. Multimodal imaging by two-photon autofluorescence and second harmonic generation allowed visualization of different features in the TM without labels and without disruption of the TM or surrounding tissues. MPM gonioscopy is a promising noninvasive imaging tool for high-resolution studies of the AOS, and research continues to explore the potential for future clinical applications in humans.

Multiphoton gonioscopy to image the trabecular meshwork of porcine eyes

NASA Astrophysics Data System (ADS)

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

2013-03-01

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

Preserve America News

Science.gov Websites

Showcase Volunteers Department of the Interior Offers Award Send Us Your Heritage Tourism Experiences heritage tourism and historic preservation programs and projects that meet the 2009 Preserve America more here. Download the application here. Send Us Your Heritage Tourism Experiences Preserve America

Preserve America News

Science.gov Websites

Two Preserve America Stewards Partners in Tourism Announce First Cultural Heritage Tourism Exchange Heritage Tourism Survival Toolkit Links About Preserve America Communities Grants PreserveAmerica.gov Tourism Announce First Cultural Heritage Tourism Exchange Partners in Tourism Annouce First Cultural

Preservation in the Age of Google: Digitization, Digital Preservation, and Dilemmas

ERIC Educational Resources Information Center

Conway, Paul

2010-01-01

The cultural heritage preservation community now functions largely within the environment of digital technologies. This article begins by juxtaposing definitions of the terms "digitization for preservation" and "digital preservation" within a sociotechnical environment for which Google serves as a relevant metaphor. It then reviews two reports…

The radiographic trabecular pattern of hips in patients with hip fractures and in elderly control subjects.

PubMed

Geraets, W G; Van der Stelt, P F; Lips, P; Van Ginkel, F C

1998-02-01

Due to the increasing number of osteoporotic fractures of hip, spine, and wrist there is a growing need for methods to track down the subjects with inferior bone structure and to monitor the effects of therapeutic measures. This study aims at a noninvasive diagnostic tool, deriving architectural properties of trabecular bone from in vivo measurements on plane radiographic films. Pelvic radiographs of the nonfractured hips of 81 patients with hip fractures and of the right hips of 74 controls were studied. The regions of interest, 2 x 2 cm2, located in the femoral neck, were sampled and digitized with a video camera connected to an image analysis system. Several geometrical and directional measurements were made. The measurements were evaluated by statistical comparison with fracture risk, gender, and Singh index. By discriminant analysis, type of fracture, as well as gender and Singh index could be predicted correctly for 58% of the subjects, whereas guessing would be correct in only 8%. It was found that the geometrical parameters discriminate between hips of controls and patients. With respect to the directional measurements associations were found with gender and Singh index. Although the new parameters assess fracture risk less accurately than bone density measurements, some parameters suggest by their behavior that they are relevant with respect to femoral bone architecture and its mechanical behavior. Although interpretation of the measurements in histological concepts requires methods that have been reported in literature only recently, it is concluded that digital analysis of the radiographic trabecular pattern is an interesting option to increase the diagnostic yield of plane film radiographs and to study the structure of bone in vivo.

The effect of a short-term delay of puberty on trabecular bone mass and structure in female rats: A texture-based and histomorphometric analysis.

PubMed Central

Yingling, Vanessa R; Xiang, Yongqing; Raphan, Theodore; Schaffler, Mitchell; Koser, Karen; Malique, Rumena

2007-01-01

Accrual of bone mass and strength during development is imperative in order to reduce the risk of fracture later in life. Although delayed pubertal onset is associated with an increased incidence of stress fracture, evidence supports the concept of “catch up” growth. It remains unclear if deficits in bone mass associated with delayed puberty have long term effects on trabecular bone structure and strength. The purpose of this study was to use texture-based analysis and histomorphometry to investigate the effect of a delay in puberty on trabecular bone mass and structure immediately post-puberty and at maturity in female rats. Forty-eight female Sprague Dawley rats (25 days) were randomly assigned to one of four groups; 1) short-term control (C-ST), 2) long-term control (C-LT), 3) short-term GnRH antagonist (G-ST) and 4) long-term GnRH antagonist (G-LT). Injections of either saline or gonadotropin-releasing hormone antagonist (GnRH-a) (100 μg/day) (Cetrotide™, Serono, Inc) were given intraperitoneally for 18 days (day 35–42) to both ST and LT. The ST groups were sacrificed after the last injection (day 43) and the LT groups at 6 months of age. Pubertal and gonadal development was retarded by the GnRA antagonist injections as indicated by a delay in vaginal opening, lower ovarian and uterine weights and suppressed estradiol levels in the short-term experimental animals (G-ST). Delayed puberty caused a transient reduction in trabecular bone area as assessed by histomorphometry. Specifically, the significant deficit in bone area resulted from a decreased number of trabecula and an increase in trabecular separation. Texture analysis, a new method to assess bone density and structural anisotropy, correlated well with the standard histomorphometry and measured significant deficits in the density measure (MDensity) in the G-ST group that remained at maturity (6 months). The texture energy deficit in the G-ST group was primarily in the 0° orientation (−13

Imaging of trabecular meshwork using Bessel-Gauss light sheet with fluorescence

NASA Astrophysics Data System (ADS)

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

2017-03-01

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

Age-related posterior ciliary muscle restriction – A link between trabecular meshwork and optic nerve head pathophysiology

PubMed Central

Lütjen-Drecoll, Elke; Kaufman, Paul L.

2016-01-01

The ciliary muscle plays a major role in controlling both accommodation and outflow facility in primates. The ciliary muscle and the choroid functionally form an elastic network that extends from the trabecular meshwork all the way to the back of the eye and ultimately attaches to the elastic fiber ring that surrounds the optic nerve and to the lamina cribrosa through which the nerve passes. The ciliary muscle governs the accommodative movement of the elastic network. With age ciliary muscle mobility is restricted by progressively inelastic posterior attachments and the posterior restriction makes the contraction progressively isometric; placing increased tension on the optic nerve region. In addition, outflow facility also declines with age and limbal corneoscleral contour bows inward. Age-related loss in muscle movement and altered limbal corneoscleral contour could both compromise the basal function of the trabecular meshwork. Further, recent studies in non-human primates show that the central vitreous moves posteriorly all the way back to the optic nerve region, suggesting a fluid current and a pressure gradient toward the optic nerve. Thus, there may be pressure and tension spikes on the optic nerve region during accommodation and these pressure and tension spikes may increase with age. This constellation of events could be relevant to glaucomatous optic neuropathy. In summary, our hypothesis is that glaucoma and presbyopia may be literally linked to each other, via the choroid, and that damage to the optic nerve may be inflicted by accommodative intraocular pressure and choroidal tension “spikes”, which may increase with age. PMID:27453343

Novel molecular insights into RhoA GTPase-induced resistance to aqueous humor outflow through the trabecular meshwork

PubMed Central

Zhang, Min; Maddala, Rupalatha; Rao, Ponugoti Vasantha

2008-01-01

Impaired drainage of aqueous humor through the trabecular meshwork (TM) culminating in increased intraocular pressure is a major risk factor for glaucoma, a leading cause of blindness worldwide. Regulation of aqueous humor drainage through the TM, however, is poorly understood. The role of RhoA GTPase-mediated actomyosin organization, cell adhesive interactions, and gene expression in regulation of aqueous humor outflow was investigated using adenoviral vector-driven expression of constitutively active mutant of RhoA (RhoAV14). Organ-cultured anterior segments from porcine eyes expressing RhoAV14 exhibited significant reduction of aqueous humor outflow. Cultured TM cells expressing RhoAV14 exhibited a pronounced contractile morphology, increased actin stress fibers, and focal adhesions and increased levels of phosphorylated myosin light chain (MLC), collagen IV, fibronectin, and laminin. cDNA microarray analysis of RNA extracted from RhoAV14-expressing human TM cells revealed a significant increase in the expression of genes encoding extracellular matrix (ECM) proteins, cytokines, integrins, cytoskeletal proteins, and signaling proteins. Conversely, various ECM proteins stimulated robust increases in phosphorylation of MLC, paxillin, and focal adhesion kinase and activated Rho GTPase and actin stress fiber formation in TM cells, indicating a potential regulatory feedback interaction between ECM-induced mechanical strain and Rho GTPase-induced isometric tension in TM cells. Collectively, these data demonstrate that sustained activation of Rho GTPase signaling in the aqueous humor outflow pathway increases resistance to aqueous humor outflow through the trabecular pathway by influencing the actomyosin assembly, cell adhesive interactions, and the expression of ECM proteins and cytokines in TM cells. PMID:18799648

Machine learning based analytics of micro-MRI trabecular bone microarchitecture and texture in type 1 Gaucher disease.

PubMed

Sharma, Gulshan B; Robertson, Douglas D; Laney, Dawn A; Gambello, Michael J; Terk, Michael

2016-06-14

Type 1 Gaucher disease (GD) is an autosomal recessive lysosomal storage disease, affecting bone metabolism, structure and strength. Current bone assessment methods are not ideal. Semi-quantitative MRI scoring is unreliable, not standardized, and only evaluates bone marrow. DXA BMD is also used but is a limited predictor of bone fragility/fracture risk. Our purpose was to measure trabecular bone microarchitecture, as a biomarker of bone disease severity, in type 1 GD individuals with different GD genotypes and to apply machine learning based analytics to discriminate between GD patients and healthy individuals. Micro-MR imaging of the distal radius was performed on 20 type 1 GD patients and 10 healthy controls (HC). Fifteen stereological and textural measures (STM) were calculated from the MR images. General linear models demonstrated significant differences between GD and HC, and GD genotypes. Stereological measures, main contributors to the first two principal components (PCs), explained ~50% of data variation and were significantly different between males and females. Subsequent PCs textural measures were significantly different between GD patients and HC individuals. Textural measures also significantly differed between GD genotypes, and distinguished between GD patients with normal and pathologic DXA scores. PCA and SVM predictive analyses discriminated between GD and HC with maximum accuracy of 73% and area under ROC curve of 0.79. Trabecular STM differences can be quantified between GD patients and HC, and GD sub-types using micro-MRI and machine learning based analytics. Work is underway to expand this approach to evaluate GD disease burden and treatment efficacy. Copyright © 2016 Elsevier Ltd. All rights reserved.

Using Anisotropic 3D Minkowski Functionals for Trabecular Bone Characterization and Biomechanical Strength Prediction in Proximal Femur Specimens

PubMed Central

Nagarajan, Mahesh B.; De, Titas; Lochmüller, Eva-Maria; Eckstein, Felix; Wismüller, Axel

2017-01-01

The ability of Anisotropic Minkowski Functionals (AMFs) to capture local anisotropy while evaluating topological properties of the underlying gray-level structures has been previously demonstrated. We evaluate the ability of this approach to characterize local structure properties of trabecular bone micro-architecture in ex vivo proximal femur specimens, as visualized on multi-detector CT, for purposes of biomechanical bone strength prediction. To this end, volumetric AMFs were computed locally for each voxel of volumes of interest (VOI) extracted from the femoral head of 146 specimens. The local anisotropy captured by such AMFs was quantified using a fractional anisotropy measure; the magnitude and direction of anisotropy at every pixel was stored in histograms that served as a feature vectors that characterized the VOIs. A linear multi-regression analysis algorithm was used to predict the failure load (FL) from the feature sets; the predicted FL was compared to the true FL determined through biomechanical testing. The prediction performance was measured by the root mean square error (RMSE) for each feature set. The best prediction performance was obtained from the fractional anisotropy histogram of AMF Euler Characteristic (RMSE = 1.01 ± 0.13), which was significantly better than MDCT-derived mean BMD (RMSE = 1.12 ± 0.16, p<0.05). We conclude that such anisotropic Minkowski Functionals can capture valuable information regarding regional trabecular bone quality and contribute to improved bone strength prediction, which is important for improving the clinical assessment of osteoporotic fracture risk. PMID:29170581

Assessment of bone mineral density by DXA and the trabecular microarchitecture of the calcaneum by texture analysis in pre- and postmenopausal women in the evaluation of osteoporosis.

PubMed

Karunanithi, R; Ganesan, S; Panicker, T M R; Korath, M Paul; Jagadeesan, K

2007-10-01

The in vivo evaluation of trabecular bone structure could be useful in the diagnosis of osteoporosis for the characterization of therapeutic response and understanding the role of parameters other than bone mineral density (BMD) in defining skeletal status. This study was made to evaluate changes taking place in the trabecular architecture of bone with age and menopausal status in women. The findings are compared with the femoral neck bone as well as the trochantar bone mineral density determined by dual energy X-ray absorptiometry (DXA), which is a standard reference test for evaluation of osteoporosis. Seventy females were recruited for the study, 25 premenopausal (mean age ± SD: 39.4 ± 3.8) and 45 postmenopausal (mean age ± SD: 57.9 ± 7.9) women. The right femoral neck bone mineral density was measured for them by dual energy X-ray absorptiometry (DXA). For the same individuals, lateral view radiographs of the right calcaneum were taken as well. The radiographs were digitized and the region of interest (ROI) of 256 × 256 pixels was selected, the run length matrix was computed for calculating seven parameters [Table 1] and the two dimensional fast Fourier transform of the image was calculated. Using the FFT, the power spectral density (PSD) was derived and the root mean square (RMS) value was determined. Our results confirm that age has a significant influence on the texture of the trabecular bone and bone mineral density.

Preserve America Summit

Science.gov Websites

Tell Us How You Would Build a Preservation Ethic and Public Appreciation for History Please share your thoughts with us. How would you build a preservation ethic and public appreciation for history? Email us at preservation, education, history and related fields met in Detroit, Michigan, on August 8, 2006, to begin

Socket preservation.

PubMed

Fee, L

2017-04-21

Socket preservation maintains bone volume post-extraction in anticipation of an implant placement or fixed partial denture pontic site. This procedure helps compensate for the resorption of the facial bone wall. Socket preservation should be considered when implant placement needs to be delayed for patient or site-related reasons. The ideal healing time before implant placement is six months. Socket preservation can reduce the need for later bone augmentation. By reducing bone resorption and accelerating bone formation it increases implant success and survival. Biomaterials for socket grafting including autograft, allograft, xenograft and alloplast. A bone substitute with a low substitution rate is recommended.

The Electroporation as a Tool for Studying the Role of Plasma Membrane in the Mechanism of Cytotoxicity of Bisphosphonates and Menadione.

PubMed

Šilkūnas, Mantas; Saulė, Rita; Batiuškaitė, Danutė; Saulis, Gintautas

2016-10-01

In this study, the role of the cell plasma membrane as a barrier in the mechanism of the cytotoxicity of nitrogen-containing bisphosphonates and menadione was studied, and the possibility of increasing the efficiency of bisphosphonates and menadione (vitamin K 3 ) as chemotherapeutic agents by permeabilizing the cell plasma membrane has been investigated in vitro. The plasma membrane barrier was reduced by electropermeabilization with the pulse of strong electric field. Two membrane-impermeant bisphosphonates with different hydrophilicities were chosen as study objects: ibandronate and pamidronate. For the comparison, an amphiphilic vitamin K 3 , which is able to cross the cell membrane, was studied as well. The impact of nitrogen-containing bisphosphonates and vitamin K 3 on MH-22A cells viability was evaluated for the case of long (9 days) and short (20 min) exposure. When cells were cultured in the medium with vitamin K 3 for 9-10 days, it exhibited toxicity of 50 % over the control at 6.2 µM for mouse hepatoma MH-22A cells. Ibandronate and pamidronate were capable of reducing drastically the cell viability only in the case of long 9-days incubation and at high concentrations (~20 µM for pamidronate and over 100 µM for ibandronate). Single, square-wave electric pulse with the duration of 100 µs and the field strength of 2 kV/cm was used to electroporate mouse hepatoma MH-22A cells in vitro. The results obtained here showed that the combination of the exposure of cells to membrane-impermeable bisphosphonates pamidronate and ibandronate with electropermeabilization of the cell plasma membrane did not increase their cytotoxicity. In the case of membrane-permeable vitamin K 3 , cell electropermeabilization did increase vitamin K 3 killing efficiency. However, this increase was not substantial, within the range of 20-30 % depending on the duration of the exposure. Electropermeabilization improved cytotoxic effect of vitamin K 3 but not of pamidronate

New bone formation and trabecular bone microarchitecture of highly porous tantalum compared to titanium implant threads: A pilot canine study.

PubMed

Lee, Jin Whan; Wen, Hai Bo; Gubbi, Prabhu; Romanos, Georgios E

2018-02-01

This study evaluated new bone formation activities and trabecular bone microarchitecture within the highly porous region of Trabecular Metal™ Dental Implants (TM) and between the threads of Tapered Screw-Vent® Dental Implants (TSV) in fresh canine extraction sockets. Eight partially edentulated dogs received four implants (4.1 mmD × 13 mmL) bilaterally in mandibular fresh extraction sockets (32 TM, 32 TSV implants), and allowed to heal for 2, 4, 8, and 12 weeks. Calcein was administered to label mineralizing bone at 11 and 4 days before euthanasia for dogs undergoing all four healing periods. Biopsies taken at each time interval were examined histologically. Histomorphometric assay was conducted for 64 unstained and 64 stained slides at the region of interest (ROI) (6 mm long × 0.35 mm deep) in the midsections of the implants. Topographical and chemical analyses were also performed. Histomorphometry revealed significantly more new bone in the TM than in the TSV implants at each healing time (p = .0014, .0084, .0218, and .0251). Calcein-labeled data showed more newly mineralized bone in the TM group than in the TSV group at 2, 8, and 12 weeks (p = .045, .028, .002, respectively) but not at 4 weeks (p = .081). Histologically TM implants exhibited more bone growth and dominant new immature woven bone at an earlier time point than TSV implants. The parameters representing trabecular bone microarchitecture corroborated faster new bone formation in the TM implants when compared to the TSV implants. TM exhibited an irregular faceted topography compared to a relatively uniform microtextured surface for TSV. Chemical analysis showed peaks associated with each implant's composition material, and TSV also showed peaks reflecting the elements of the calcium phosphate blasting media. Results suggest that the healing pathway associated with the highly porous midsection of TM dental implant could enable faster and stronger secondary implant stability than

Preservation Environments

NASA Technical Reports Server (NTRS)

Moore, Reagan W.

2004-01-01

The long-term preservation of digital entities requires mechanisms to manage the authenticity of massive data collections that are written to archival storage systems. Preservation environments impose authenticity constraints and manage the evolution of the storage system technology by building infrastructure independent solutions. This seeming paradox, the need for large archives, while avoiding dependence upon vendor specific solutions, is resolved through use of data grid technology. Data grids provide the storage repository abstractions that make it possible to migrate collections between vendor specific products, while ensuring the authenticity of the archived data. Data grids provide the software infrastructure that interfaces vendor-specific storage archives to preservation environments.

Modes of fossil preservation

USGS Publications Warehouse

Schopf, J.M.

1975-01-01

The processes of geologic preservation are important for understanding the organisms represented by fossils. Some fossil differences are due to basic differences in organization of animals and plants, but the interpretation of fossils has also tended to be influenced by modes of preservation. Four modes of preservation generally can be distinguished: (1) Cellular permineralization ("petrifaction") preserves anatomical detail, and, occasionally, even cytologic structures. (2) Coalified compression, best illustrated by structures from coal but characteristic of many plant fossils in shale, preserves anatomical details in distorted form and produces surface replicas (impressions) on enclosing matrix. (3) Authigenic preservation replicates surface form or outline (molds and casts) prior to distortion by compression and, depending on cementation and timing, may intergrade with fossils that have been subject to compression. (4) Duripartic (hard part) preservation is characteristic of fossil skeletal remains, predominantly animal. Molds, pseudomorphs, or casts may form as bulk replacements following dissolution of the original fossil material, usually by leaching. Classification of the kinds of preservation in fossils will aid in identifying the processes responsible for modifying the fossil remains of both animals and plants. ?? 1975.

Serum FGF-21 levels are associated with worsened radial trabecular bone microarchitecture and decreased radial bone strength in women with anorexia nervosa.

PubMed

Fazeli, Pouneh K; Faje, Alexander T; Cross, Ela J; Lee, Hang; Rosen, Clifford J; Bouxsein, Mary L; Klibanski, Anne

2015-08-01

Anorexia nervosa (AN) is a psychiatric disorder characterized by self-induced starvation and low body weight. Women with AN have impaired bone formation, low bone mass and an increased risk of fracture. FGF-21 is a hormone secreted by the liver in starvation and FGF-21 transgenic mice have significant bone loss due to an uncoupling of bone resorption and bone formation. We hypothesized that FGF-21 may contribute to the low bone mass state of AN. We studied 46 women: 20 with AN (median age [interquartile range]: 27.5 [25, 30.75] years) and 26 normal-weight controls (NWC) of similar age (25 [24, 28.5] years). We investigated associations between serum FGF-21 and 1) aBMD measured by dual energy X-ray absorptiometry, 2) parameters of bone microarchitecture in the distal radius and tibia measured by high-resolution peripheral quantitative CT and 3) bone strength, estimated by microfinite element analysis. FGF-21 levels were similar in AN and NWC (AN: 33.1 [18.1, 117.0] pg/ml vs. NWC: 57.4 [23.8, 107.1] pg/ml; p = 0.54). There was a significant inverse association between log FGF-21 and trabecular number in the radius in both AN (R = -0.57, p < 0.01) and NWC (R=-0.53, p < 0.01) and a significant positive association between log FGF-21 and trabecular separation in the radius in AN (R = 0.50, p < 0.03) and NWC (R = 0.52, p < 0.01). Estimates of radial bone strength were inversely associated with log FGF-21 in AN (R = -0.50, p < 0.03 for both stiffness and failure load). There were no associations between FGF-21 and aBMD, cortical parameters or tibial parameters in the AN or NWC groups. FGF-21 may be an important determinant of trabecular skeletal homeostasis in AN. Copyright © 2015 Elsevier Inc. All rights reserved.

Influence of implant diameter in the displacement of dental implants in trabecular bovine bone under a static lateral load: experimental results and computational modeling.

PubMed

Engelke, Wilfried; Decco, Oscar A; Cura, Andrea C; Maldonado, Isai; Crippa, Federico G

2014-12-01

Primary stability and micromovement of dental implants depend on structural properties of the surrounding bone and on implant dimension and design. The purpose of this study was to provide objective data for the influence of implant diameter on the displacement of titanium screw implants. Ninety Semados implants (length 15 mm, diameter 3.25, 3.75, and 4.5 mm; Bego, Bremen, Germany) were inserted in trabecular bone specimens. All implants were inserted with a torque up to 30 N·cm and loaded horizontally with 10, 20, and 30 N for 2 seconds. All implants showed primary stability. With increasing force, a gradual increase of micromovement was observed (Kruskal-Wallis test, P = 0.000). No significant differences were found (Kruskal-Wallis test, P = 0.148) comparing different diameters for every force. Variation of the diameter of standard implants between 3.25 and 4.5 mm does not seem to influence the primary stability in trabecular bone specimen. Differences between experimental and computational results may be due to the simplification used when modeling.

Comparison of the Lag Screw Placements for the Treatment of Stable and Unstable Intertrochanteric Femoral Fractures regarding Trabecular Bone Failure.

PubMed

Celik, Talip; Mutlu, Ibrahim; Ozkan, Arif; Kisioglu, Yasin

2016-01-01

Background. In this study, the cut-out risk of Dynamic Hip Screw (DHS) was investigated in nine different positions of the lag screw for two fracture types by using Finite Element Analysis (FEA). Methods. Two types of fractures (31-A1.1 and A2.1 in AO classification) were generated in the femur model obtained from Computerized Tomography images. The DHS model was placed into the fractured femur model in nine different positions. Tip-Apex Distances were measured using SolidWorks. In FEA, the force applied to the femoral head was determined according to the maximum value being observed during walking. Results. The highest volume percentage exceeding the yield strength of trabecular bone was obtained in posterior-inferior region in both fracture types. The best placement region for the lag screw was found in the middle of both fracture types. There are compatible results between Tip-Apex Distances and the cut-out risk except for posterior-superior and superior region of 31-A2.1 fracture type. Conclusion. The position of the lag screw affects the risk of cut-out significantly. Also, Tip-Apex Distance is a good predictor of the cut-out risk. All in all, we can supposedly say that the density distribution of the trabecular bone is a more efficient factor compared to the positions of lag screw in the cut-out risk.

Comparison of the Lag Screw Placements for the Treatment of Stable and Unstable Intertrochanteric Femoral Fractures regarding Trabecular Bone Failure

PubMed Central

Mutlu, Ibrahim; Ozkan, Arif; Kisioglu, Yasin

2016-01-01

Background. In this study, the cut-out risk of Dynamic Hip Screw (DHS) was investigated in nine different positions of the lag screw for two fracture types by using Finite Element Analysis (FEA). Methods. Two types of fractures (31-A1.1 and A2.1 in AO classification) were generated in the femur model obtained from Computerized Tomography images. The DHS model was placed into the fractured femur model in nine different positions. Tip-Apex Distances were measured using SolidWorks. In FEA, the force applied to the femoral head was determined according to the maximum value being observed during walking. Results. The highest volume percentage exceeding the yield strength of trabecular bone was obtained in posterior-inferior region in both fracture types. The best placement region for the lag screw was found in the middle of both fracture types. There are compatible results between Tip-Apex Distances and the cut-out risk except for posterior-superior and superior region of 31-A2.1 fracture type. Conclusion. The position of the lag screw affects the risk of cut-out significantly. Also, Tip-Apex Distance is a good predictor of the cut-out risk. All in all, we can supposedly say that the density distribution of the trabecular bone is a more efficient factor compared to the positions of lag screw in the cut-out risk. PMID:27995133

Wood preservation

Treesearch

Stan T. Lebow

2010-01-01

Many commonly used wood species can deteriorate if exposed to conditions that support growth of wood-degrading organisms (see Chap. 14). Wood products can be protected from the attack of decay fungi, harmful insects, or marine borers by applying chemical preservatives. Preservative treatments greatly increase the life of wood structures, thus reducing replacement costs...

Aqueous outflow - a continuum from trabecular meshwork to episcleral veins

PubMed Central

Carreon, Teresia; van der Merwe, Elizabeth; Fellman, Ronald L.; Johnstone, Murray; Bhattacharya, Sanjoy K.

2016-01-01

In glaucoma, lowered intraocular pressure (IOP) confers neuroprotection. Elevated IOP characterizes glaucoma and arises from impaired aqueous humor (AH) outflow. Increased resistance in the trabecular meshwork (TM), a filter-like structure essential to regulate AH outflow, may result in the impaired outflow. Flow through the 360° circumference of TM structures may be non-uniform, divided into high and low flow regions, termed as segmental. After flowing through the TM, AH enters Schlemm’s canal (SC), which expresses both blood and lymphatic markers; AH then passes into collector channel entrances (CCE) along the SC external well. From the CCE, AH enters a deep scleral plexus (DSP) of vessels that typically run parallel to SC. From the DSP, intrascleral collector vessels run radially to the scleral surface to connect with AH containing vessels called aqueous veins to discharge AH to blood-containing episcleral veins. However, the molecular mechanisms that maintain homeostatic properties of endothelial cells along the pathways are not well understood. How these molecular events change during aging and in glaucoma pathology remain unresolved. In this review, we propose mechanistic possibilities to explain the continuum of AH outflow control, which originates at the TM and extends through collector channels to the episcleral veins. PMID:28028002

Direct trabecular meshwork imaging in porcine eyes through multiphoton gonioscopy

PubMed Central

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

2013-01-01

Abstract. The development of technologies to characterize the ocular aqueous outflow system (AOS) is important for the understanding of the pathophysiology of glaucoma. Multiphoton microscopy (MPM) offers the advantage of high-resolution, label-free imaging with intrinsic image contrast because the emitted signals result from the specific biomolecular content of the tissue. Previous attempts to use MPM to image the murine irido-corneal region directly through the sclera have suffered from degradation in image resolution due to scattering of the focused laser light. As a result, transscleral MPM has limited ability to observe fine structures in the AOS. In this work, the porcine irido-corneal angle was successfully imaged through the transparent cornea using a gonioscopic lens to circumvent the highly scattering scleral tissue. The resulting high-resolution images allowed the detailed structures in the trabecular meshwork (TM) to be observed. Multimodal imaging by two-photon autofluorescence and second harmonic generation allowed visualization of different features in the TM without labels and without disruption of the TM or surrounding tissues. MPM gonioscopy is a promising noninvasive imaging tool for high-resolution studies of the AOS, and research continues to explore the potential for future clinical applications in humans. PMID:23515864

Preservation of Digital Objects.

ERIC Educational Resources Information Center

Galloway, Patricia

2004-01-01

Presents a literature review that covers the following topics related to preservation of digital objects: practical examples; stakeholders; recordkeeping standards; genre-specific problems; trusted repository standards; preservation methods; preservation metadata standards; and future directions. (Contains 82 references.) (MES)

Identification of a constitutive law for trabecular bone samples under remodeling in the framework of irreversible thermodynamics

NASA Astrophysics Data System (ADS)

Louna, Zineeddine; Goda, Ibrahim; Ganghoffer, Jean-François

2018-01-01

We construct in the present paper constitutive models for bone remodeling based on micromechanical analyses at the scale of a representative unit cell (RUC) including a porous trabecular microstructure. The time evolution of the microstructure is simulated as a surface remodeling process by relating the surface growth remodeling velocity to a surface driving force incorporating a (surface) Eshelby tensor. Adopting the framework of irreversible thermodynamics, a 2D constitutive model based on the setting up of the free energy density and a dissipation potential is identified from FE simulations performed over a unit cell representative of the trabecular architecture obtained from real bone microstructures. The static and evolutive effective properties of bone at the scale of the RUC are obtained by combining a methodology for the evaluation of the average kinematic and static variables over a prototype unit cell and numerical simulations with controlled imposed first gradient rates. The formulated effective growth constitutive law at the scale of the homogenized set of trabeculae within the RUC is of viscoplastic type and relates the average growth strain rate to the homogenized stress tensor. The postulated model includes a power law function of an effective stress chosen to depend on the first and second stress invariants. The model coefficients are calibrated from a set of virtual testing performed over the RUC subjected to a sequence of loadings. Numerical simulations show that overall bone growth does not show any growth kinematic hardening. The obtained results quantify the strength and importance of different types of external loads (uniaxial tension, simple shear, and biaxial loading) on the overall remodeling process and the development of elastic deformations within the RUC.

Novel Technique: Knee Arthrodesis Using Trabecular Metal Cones with Intramedullary Nailing and Intramedullary Autograft.

PubMed

Peterson, Blake E; Bal, Sonny; Aggarwal, Ajay; Crist, Brett D

2016-08-01

The failed total knee arthroplasty is a challenge to the surgeon and the patient. Infection, bone loss, and instability lead to a chronically painful and dysfunctional limb. Two-stage revision arthroplasty has been successful in clearing a majority of periprosthetic joint infections. However, there are many cases when the multiply revised and infected total knee arthroplasty cannot be salvaged. We report, a review of knee arthrodesis and a novel technique to manage significant bone loss. The use of trabecular metal cones and a long intramedullary nail can be used in concert with an autologous intramedullary bone graft to provide a stable, length restoring construct with sufficient biology to heal very large bone voids. With this technique we have successfully restored function and stability in the failed knee arthroplasty. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Microbiological preservation of cucumbers for bulk storage using acetic acid and food preservatives.

PubMed

Pérez-Díaz, I M; McFeeters, R F

2008-08-01

Microbial growth did not occur when cucumbers were preserved without a thermal process by storage in solutions containing acetic acid, sodium benzoate, and calcium chloride to maintain tissue firmness. The concentrations of acetic acid and sodium benzoate required to ensure preservation were low enough so that stored cucumbers could be converted to the finished product without the need to wash out and discard excess acid or preservative. Since no thermal process was required, this method of preservation would be applicable for storing cucumbers in bulk containers. Acid tolerant pathogens died off in less than 24 h with the pH, acetic acid, and sodium benzoate concentrations required to assure the microbial stability of cucumbers stored at 30 degrees C. Potassium sorbate as a preservative in this application was not effective. Yeast growth was observed when sulfite was used as a preservative.

Formax Preserved Birds

ERIC Educational Resources Information Center

Sheridan, Philip

1978-01-01

A quick, simple method for preserving bird specimens using borax and a formalin solution is described. Procedures for injecting and mounting the specimens are given along with certain restrictions on preserving specimens. (MA)

Type 1 Diabetes in Young Rats Leads to Progressive Trabecular Bone Loss, Cessation of Cortical Bone Growth, and Diminished Whole Bone Strength and Fatigue Life

PubMed Central

Silva, Matthew J.; Brodt, Michael D.; Lynch, Michelle A.; McKenzie, Jennifer A.; Tanouye, Kristi M.; Nyman, Jeffry S.; Wang, Xiaodu

2009-01-01

People with diabetes have increased risk of fracture disproportionate to BMD, suggesting reduced material strength (quality). We quantified the skeletal effects of type 1 diabetes in the rat. Fischer 344 and Sprague-Dawley rats (12 wk of age) were injected with either vehicle (Control) or streptozotocin (Diabetic). Forelimbs were scanned at 0, 4, 8, and 12 wk using pQCT. Rats were killed after 12 wk. We observed progressive osteopenia in diabetic rats. Trabecular osteopenia was caused by bone loss: volumetric BMD decreased progressively with time in diabetic rats but was constant in controls. Cortical osteopenia was caused by premature arrest of cortical expansion: cortical area did not increase after 4–8 wk in diabetic rats but continued to increase in controls. Postmortem μCT showed a 60% reduction in proximal tibial trabecular BV/TV in diabetic versus control rats, whereas moments of inertia of the ulnar and femoral diaphysis were reduced ∼30%. Monotonic bending tests indicated that ulna and femora from diabetic animals were ∼25% less stiff and strong versus controls. Estimates of material properties indicated no changes in elastic modulus or ultimate stress but modest (∼10%) declines in yield stress for diabetic bone. These changes were associated with a ∼50% increase in the nonenzymatic collagen cross-link pentosidine. Last, cyclic testing showed diminished fatigue life in diabetic bones at the structural (force) level but not at the material (stress) level. In summary, type 1 diabetes, left untreated, causes trabecular bone loss and a reduction in diaphyseal growth. Diabetic bone has greatly increased nonenzymatic collagen cross-links but only modestly reduced material properties. The loss of whole bone strength under both monotonic and fatigue loading is attributed mainly to reduced bone size. PMID:19338453

Evaluation of RNA from human trabecular bone and identification of stable reference genes.

PubMed

Cepollaro, Simona; Della Bella, Elena; de Biase, Dario; Visani, Michela; Fini, Milena

2018-06-01

The isolation of good quality RNA from tissues is an essential prerequisite for gene expression analysis to study pathophysiological processes. This study evaluated the RNA isolated from human trabecular bone and defined a set of stable reference genes. After pulverization, RNA was extracted with a phenol/chloroform method and then purified using silica columns. The A260/280 ratio, A260/230 ratio, RIN, and ribosomal ratio were measured to evaluate RNA quality and integrity. Moreover, the expression of six candidates was analyzed by qPCR and different algorithms were applied to assess reference gene stability. A good purity and quality of RNA was achieved according to A260/280 and A260/230 ratios, and RIN values. TBP, YWHAZ, and PGK1 were the most stable reference genes that should be used for gene expression analysis. In summary, the method proposed is suitable for gene expression evaluation in human bone and a set of reliable reference genes has been identified. © 2017 Wiley Periodicals, Inc.

The poro-viscoelastic properties of trabecular bone: a micro computed tomography-based finite element study.

PubMed

Sandino, Clara; McErlain, David D; Schipilow, John; Boyd, Steven K

2015-04-01

Bone is a porous structure with a solid phase that contains hydroxyapatite and collagen. Due to its composition, bone is often represented either as a poroelastic or as a viscoelastic material; however, the poro-viscoelastic formulation that allows integrating the effect of both the fluid flow and the collagen on the mechanical response of the tissue, has not been applied yet. The objective of this study was to develop a micro computed tomography (µCT)-based finite element (FE) model of trabecular bone that includes both the poroelastic and the viscoelastic nature of the tissue. Cubes of trabecular bone (N=25) from human distal tibia were scanned with µCT and stress relaxation experiments were conducted. The µCT images were the basis for sample specific FE models, and the stress relaxation experiments were simulated applying a poro-viscoelastic formulation. The model considers two scales of the tissue: the intertrabecular pore and the lacunar-canalicular pore scales. Independent viscoelastic and poroelastic models were also developed to determine their contribution to the poro-viscoelastic model. All the experiments exhibited a similar relaxation trend. The average reaction force before relaxation was 9.28 × 10(2)N (SD ± 5.11 × 10(2)N), and after relaxation was 4.69 × 10(2)N (SD ± 2.88 × 10(2)N). The slope of the regression line between the force before and after relaxation was 1.92 (R(2)=0.96). The poro-viscoelastic models captured 49% of the variability of the experimental data before relaxation and 33% after relaxation. The relaxation predicted with viscoelastic models was similar to the poro-viscoelastic ones; however, the poroelastic formulation underestimated the reaction force before relaxation. These data suggest that the contribution of viscoelasticity (fluid flow-independent mechanism) to the mechanical response of the tissue is significantly greater than the contribution of the poroelasticity (fluid flow-dependent mechanism). Copyright © 2015

Laser Trabeculoplasty Induces Changes in the Trabecular Meshwork Glycoproteome: A pilot study

PubMed Central

Amelinckx, Adriana; Castello, Maria; Arrieta-Quintero, Esdras; Lee, Tinthu; Salas, Nelson; Hernandez, Eleut; Lee, Richard K.; Bhattacharya, Sanjoy K.; Parel, Jean-Marie A

2009-01-01

Laser trabeculoplasty (LT) is a commonly used modality of treatment for glaucoma. The mechanism by which LT lowers the intraocular pressure (IOP) is unknown. Using cat eyes, selective laser trabeculoplasty (SLT) with a Q-switched frequency doubled Nd:YAG laser was used to treat the trabecular meshwork (TM). Laser treated TM was then subjected to proteomic analysis for detection of molecular changes and histological analysis for the detection of structural and protein expression patterns. In addition, the protein glycosylation patterns of laser treated and non-treated TM was assessed and differentially glycosylated proteins were proteomically identified. SLT laser treatment to the TM resulted in elevated glycosylation levels compared to non-lasered TM. TM laser treatment also resulted in protein expression levels changes of several proteins. Elevated levels of biglycan, keratocan and prolargin were detected in laser treated TM compared to non-lasered controls. Further investigation is anticipated to provide insight into how glycosylation changes affect TM proteins and TM regulation of aqueous outflow in response to laser trabeculoplasty. PMID:19432485

Laser trabeculoplasty induces changes in the trabecular meshwork glycoproteome: a pilot study.

PubMed

Amelinckx, Adriana; Castello, Maria; Arrieta-Quintero, Esdras; Lee, Tinthu; Salas, Nelson; Hernandez, Eleut; Lee, Richard K; Bhattacharya, Sanjoy K; Parel, Jean-Marie A

2009-07-01

Laser trabeculoplasty (LT) is a commonly used modality of treatment for glaucoma. The mechanism by which LT lowers the intraocular pressure (IOP) is unknown. With the use of cat eyes, selective laser trabeculoplasty (SLT) with a Q-switched frequency doubled Nd:YAG laser was used to treat the trabecular meshwork (TM). Laser treated TM was then subjected to proteomic analysis for detection of molecular changes and histological analysis for the detection of structural and protein expression patterns. In addition, the protein glycosylation patterns of laser treated and nontreated TM was assessed and differentially glycosylated proteins were proteomically identified. SLT laser treatment to the TM resulted in elevated glycosylation levels compared to nonlasered TM. TM laser treatment also resulted in protein expression levels changes of several proteins. Elevated levels of biglycan, keratocan and prolargin were detected in laser treated TM compared to nonlasered controls. Further investigation is anticipated to provide insight into how glycosylation changes affect TM proteins and TM regulation of aqueous outflow in response to laser trabeculoplasty.

TBS (Trabecular Bone Score) Expands Understanding of Spaceflight Effects on the Lumbar Spine of Long-Duration Astronauts

NASA Technical Reports Server (NTRS)

Smith, Scott A.; Watts, Nelson; Hans, Didier; LeBlanc, Adrian; Spector, Elisabeth; King, Lisa; Sibonga, Jean

2014-01-01

Bone loss due to long-duration spaceflight has been characterized by both DXA and QCT serial scans. It is unclear if these spaceflight-induced changes in bone mineral density (BMD) and structure result in increased fracture incidence. NASA astronauts currently fly 5 to 6-month missions on the International Space Station (ISS) and at least one 12-month mission is planned. While NASA has measured areal BMD (by DXA) and volumetric BMD (by QCT) and has estimated hip strength (by finite element models of QCT data, no method has yet been used to examine bone micro-architecture from lumbar spine (LS). DXA scans are routinely performed pre- and postflight on all ISS astronauts to follow BMD changes associated with spaceflight. Trabecular Bone Score (TBS) is a relatively new method that measures grey-scale-level texture information extracted from LS DXA images and correlates with 3D parameters of bone micro-architecture. We evaluated the ability of LS TBS to discriminate changes in astronauts who have flown on ISS missions and to determine if TBS can provide additional information compared to DXA. Methods: Lumbar Spine (L1-4) DXA scans from 51 astronauts (mean age, 47 +/- 4 yrs) were divided into 3 groups based on the exercise regimens performed onboard the ISS. "Pre-ARED" (exercise using a load-limited resistive exercise device, <300 lb), "ARED" (exercise with a high-load resistive exercise device, up to 600 lb) and "Bisphos+ARED" group (ARED exercise and a 70-mg alendronate tablet once a week before and during flight, starting 17 days before launch). DXA scans were performed and analyzed on a Hologic Discovery W using the same technician for the pre- and post-flight scans. LSC for the LS in our laboratory is 0.025 g/sq. cm. TBS was performed at the Mercy Hospital, Cincinnati, Ohio on a similar Hologic computer. Data were analyzed using a paired, 2-tailed Student's t-test for the difference between pre- and postflight means. Percent change and % change per month are noted

Yellow-bellied Marmots (Marmota flaviventris) preserve bone strength and microstructure during hibernation

PubMed Central

Wojda, Samantha J.; McGee-Lawrence, Meghan E.; Gridley, Richard A.; Auger, Janene; Black, Hal L.; Donahue, Seth W.

2012-01-01

Reduced skeletal loading typically results in decreased bone strength and increased fracture risk for humans and many other animals. Previous studies have shown bears are able to prevent bone loss during the disuse that occurs during hibernation. Studies with smaller hibernators, which arouse intermittently during hibernation, show that they may lose bone at the microstructural level. These small hibernators, like bats and squirrels, do not utilize intracortical remodeling. However, slightly larger mammals like marmots do. In this study we examined the effects of hibernation on bone structural, mineral, and mechanical properties in yellow-bellied marmots (Marmota flaviventris). This was done by comparing cortical bone properties in femurs and trabecular bone properties in tibias from marmots killed before hibernation (fall) and after hibernation (spring). Age data were not available for this study; however, based on femur length the post-hibernation marmots were larger than the pre-hibernation marmots. Thus, cross-sectional properties were normalized by allometric functions of bone length for comparisons between pre- and post-hibernation. Cortical thickness and normalized cortical area were higher in post-hibernation samples; no other normalized cross-sectional properties were different. No cortical bone microstructural loss was evident in osteocyte lacunar measurements, intracortical porosity, or intracortical remodeling cavity density. Osteocyte lacunar area, porosity, and density were surprisingly lower in post-hibernation samples. Trabecular bone volume fraction was not different between pre- and post-hibernation. Measures of both trabecular and cortical bone mineral content were higher in post-hibernation samples. Three-point bending failure load, failure energy, elastic energy, ultimate stress, and yield stress were all higher in post-hibernation samples. These results support the idea that, like bears, marmots are able to prevent disuse osteoporosis during

Yellow-bellied marmots (Marmota flaviventris) preserve bone strength and microstructure during hibernation.

PubMed

Wojda, Samantha J; McGee-Lawrence, Meghan E; Gridley, Richard A; Auger, Janene; Black, Hal L; Donahue, Seth W

2012-01-01

Reduced skeletal loading typically results in decreased bone strength and increased fracture risk for humans and many other animals. Previous studies have shown bears are able to prevent bone loss during the disuse that occurs during hibernation. Studies with smaller hibernators, which arouse intermittently during hibernation, show that they may lose bone at the microstructural level. These small hibernators, like bats and squirrels, do not utilize intracortical remodeling. However, slightly larger mammals like marmots do. In this study we examined the effects of hibernation on bone structural, mineral, and mechanical properties in yellow-bellied marmots (Marmota flaviventris). This was done by comparing cortical bone properties in femurs and trabecular bone properties in tibias from marmots killed before hibernation (fall) and after hibernation (spring). Age data were not available for this study; however, based on femur length the post-hibernation marmots were larger than the pre-hibernation marmots. Thus, cross-sectional properties were normalized by allometric functions of bone length for comparisons between pre- and post-hibernation. Cortical thickness and normalized cortical area were higher in post-hibernation samples; no other normalized cross-sectional properties were different. No cortical bone microstructural loss was evident in osteocyte lacunar measurements, intracortical porosity, or intracortical remodeling cavity density. Osteocyte lacunar area, porosity, and density were surprisingly lower in post-hibernation samples. Trabecular bone volume fraction was not different between pre- and post-hibernation. Measures of both trabecular and cortical bone mineral content were higher in post-hibernation samples. Three-point bending failure load, failure energy, elastic energy, ultimate stress, and yield stress were all higher in post-hibernation samples. These results support the idea that, like bears, marmots are able to prevent disuse osteoporosis during

Investigation of the inverse piezoelectric effect of trabecular bone on a micrometer length scale using synchrotron radiation.

PubMed

Wieland, D C F; Krywka, C; Mick, E; Willumeit-Römer, R; Bader, R; Kluess, D

2015-10-01

In the present paper we have investigated the impact of electro stimulation on microstructural parameters of the major constituents of bone, hydroxyapatite and collagen. Therapeutic approaches exhibit an improved healing rate under electric fields. However, the underlying mechanism is not fully understood so far. In this context one possible effect which could be responsible is the inverse piezo electric effect at bone structures. Therefore, we have carried out scanning X-ray microdiffraction experiments, i.e. we recorded X-ray diffraction data with micrometer resolution using synchrotron radiation from trabecular bone samples in order to investigate how the bone matrix reacts to an applied electric field. Different samples were investigated, where the orientation of the collagen matrix differed with respect to the applied electric field. Our experiments aimed to determine whether the inverse piezo electric effect could have a significant impact on the improved bone regeneration owing to electrostimulative therapy. Our data suggest that strain is in fact induced in bone by the collagen matrix via the inverse piezo electric effect which occurs in the presence of an adequately oriented electric field. The magnitude of the underlying strain is in a range where bone cells are able to detect it. In our study we report on the piezoelectric effect in bone which was already discovered and explored on a macro scale in the 1950. Clinical approaches utilize successfully electro stimulation to enhance bone healing but the exact mechanisms taking place are still a matter of debate. We have measured the stress distribution with micron resolution in trabecular bone to determine the piezo electric induced stress. Our results show that the magnitude of the induced stress is big enough to be sensed by cells and therefore, could be a trigger for bone remodeling and growth. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Skeletal dosimetry based on µCT images of trabecular bone: update and comparisons

NASA Astrophysics Data System (ADS)

Kramer, R.; Cassola, V. F.; Vieira, J. W.; Khoury, H. J.; de Oliveira Lira, C. A. B.; Robson Brown, K.

2012-06-01

Two skeletal dosimetry methods using µCT images of human bone have recently been developed: the paired-image radiation transport (PIRT) model introduced by researchers at the University of Florida (UF) in the US and the systematic-periodic cluster (SPC) method developed by researchers at the Federal University of Pernambuco in Brazil. Both methods use µCT images of trabecular bone (TB) to model spongiosa regions of human bones containing marrow cavities segmented into soft tissue volumes of active marrow (AM), trabecular inactive marrow and the bone endosteum (BE), which is a 50 µm thick layer of marrow on all TB surfaces and on cortical bone surfaces next to TB as well as inside the medullary cavities. With respect to the radiation absorbed dose, the AM and the BE are sensitive soft tissues for the induction of leukaemia and bone cancer, respectively. The two methods differ mainly with respect to the number of bone sites and the size of the µCT images used in Monte Carlo calculations and they apply different methods to simulate exposure from radiation sources located outside the skeleton. The PIRT method calculates dosimetric quantities in isolated human bones while the SPC method uses human bones embedded in the body of a phantom which contains all relevant organs and soft tissues. Consequently, the SPC method calculates absorbed dose to the AM and to the BE from particles emitted by radionuclides concentrated in organs or from radiation sources located outside the human body in one calculation step. In order to allow for similar calculations of AM and BE absorbed doses using the PIRT method, the so-called dose response functions (DRFs) have been developed based on absorbed fractions (AFs) of energy for electrons isotropically emitted in skeletal tissues. The DRFs can be used to transform the photon fluence in homogeneous spongiosa regions into absorbed dose to AM and BE. This paper will compare AM and BE AFs of energy from electrons emitted in skeletal

Summary of the preservation techniques and the evolution of the anammox bacteria characteristics during preservation.

PubMed

Chen, Hui; Jin, Ren-Cun

2017-06-01

The anaerobic ammonium oxidation (anammox) process is a promising wastewater treatment method for biological nitrogen removal. A sufficient amount of active anammox sludge as a seed is crucial to the fast establishment and stability of the anammox process. Anammox bacteria is a kind of microorganism which is sensitive to the environmental conditions, e.g., oxygen, temperature. The optimum temperature and pH for the growth of the anammox bacteria are 30-40 °C and 6.7-8.3. A proper preservation technique allows fast start-up of the anammox process, overcoming the long doubling time of anammox biomass. The preservation of the anammox sludge is influenced by various factors, e.g., preservation techniques, duration, temperature, substrates, and protective agents. During preservation, the characteristics of the anammox biomass, including the bioactivity, heme c content, extracellular polymeric substances (EPS), and sludge morphology, change with time. The optimum preservation technique is not invariable and it depends on the purpose of preservation (precedence of bioactivity or quantity), the bacterial community, and other parameters. It is important for the preserved anammox biomass to achieve reactivation so that stable anammox reactors can be established as soon as possible. However, because the preservation process is complicated, the knowledge regarding preservation is far from complete, and much future work will be required to increase the understanding of preservation.

Phase-sensitive optical coherence tomography characterization of pulse-induced trabecular meshwork displacement in ex vivo nonhuman primate eyes

NASA Astrophysics Data System (ADS)

Li, Peng; Reif, Roberto; Zhi, Zhongwei; Martin, Elizabeth; Shen, Tueng T.; Johnstone, Murray; Wang, Ruikang K.

2012-07-01

Glaucoma is a blinding disease for which intraocular pressure (IOP) is the only treatable risk factor. The mean IOP is regulated through the aqueous outflow system, which contains the trabecular meshwork (TM). Considerable evidence indicates that trabecular tissue movement regulates the aqueous outflow and becomes abnormal during glaucoma; however, such motion has thus far escaped detection. The purpose of this study is to describe anovel use of a phase-sensitive optical coherence tomography (PhS-OCT) method to assess pulse-dependent TM movement. For this study, we used enucleated monkey eyes, each mounted in an anterior segment holder. A perfusion system was used to control the mean IOP as well as to provide IOP sinusoidal transients (amplitude 3 mmHg, frequency 1 pulse/second) in all experiments. Measurements were carried out at seven graded mean IOPs (5, 8, 10, 20, 30, 40, and 50 mm Hg). We demonstrate that PhS-OCT is sensitive enough to image/visualize TM movement synchronous with the pulse-induced IOP transients, providing quantitative measurements of dynamic parameters such as velocity, displacement, and strain rate that are important for assessing the biomechanical compliance of the TM. We find that the largest TM displacement is in the area closest to Schlemm's canal (SC) endothelium. While maintaining constant ocular pulse amplitude, an increase of mean IOP results in a decrease of TM displacement and mean size of the SC. These results demonstrate that the PhS-OCT is a useful imaging technique capable of assessing functional properties necessary to maintain IOP in a healthy range, offering a new diagnostic alternative for glaucoma.

Preserve America News

Science.gov Websites

Communities Designated; Applications Available Preserve America Stewards Honored Preserve America Grants historic structures and assets. 736 Communities Designated; Applications Available 736 Communities Designated; Applications Available Just before leaving the White House, former First Lady Mrs. Laura Bush

Hyalinizing Trabecular Tumor of the Thyroid Gland, a Diagnostic Challenge in Fine-Needle Aspiration Cytology: Case Report.

PubMed

Rhee, Ye-Young; Jung, Hong Kyu; Kim, Se Hoon; Kim, Soo Hee

2018-06-11

Hyalinizing trabecular tumor (HTT) is a rare thyroid tumor with low to minimal malignant potential. HTT is often misinterpreted as other thyroid tumors, including papillary thyroid carcinoma (PTC) and medullary thyroid carcinoma (MTC), on fine-needle aspiration (FNA) cytology, because of its overlapping cytologic features, such as nuclear grooves and intranulcear pseudoinclusions. Although cytopathologists cannot definitely conclude HTT by FNA cytology, suspicion of HTT is necessary to avoid misdiagnosing HTT as PTC or MTC and to avoid unnecessary aggressive treatment. Here, we report a case of HTT with novel cytologic features in CellPrep liquid based cytology that was diagnosed as suspicious for papillary carcinoma by FNA and finally diagnosed as HTT in the surgical specimen.

Monte Carlo simulation of age-dependent radiation dose from alpha- and beta-emitting radionuclides to critical trabecular bone and bone marrow targets

NASA Astrophysics Data System (ADS)

Dant, James T.; Richardson, Richard B.; Nie, Linda H.

2013-05-01

Alpha (α) particles and low-energy beta (β) particles present minimal risk for external exposure. While these particles can induce leukemia and bone cancer due to internal exposure, they can also be beneficial for targeted radiation therapies. In this paper, a trabecular bone model is presented to investigate the radiation dose from bone- and marrow-seeking α and β emitters to different critical compartments (targets) of trabecular bone for different age groups. Two main issues are addressed with Monte Carlo simulations. The first is the absorption fractions (AFs) from bone and marrow to critical targets within the bone for different age groups. The other issue is the application of 223Ra for the radiotherapy treatment of bone metastases. Both a static model and a simulated bone remodeling process are established for trabecular bone. The results show significantly lower AFs from radionuclide sources in the bone volume to the peripheral marrow and the haematopoietic marrow for adults than for newborns and children. The AFs from sources on the bone surface and in the bone marrow to peripheral marrow and haematopoietic marrow also varies for adults and children depending on the energy of the particles. Regarding the use of 223Ra as a radionuclide for the radiotherapy of bone metastases, the simulations show a significantly higher dose from 223Ra and its progeny in forming bone to the target compartment of bone metastases than that from two other more commonly used β-emitting radiopharmaceuticals, 153Sm and 89Sr. There is also a slightly lower dose from 223Ra in forming bone to haematopoietic marrow than that from 153Sm and 89Sr. These results indicate a higher therapy efficiency and lower marrow toxicity from 223Ra and its progeny. In conclusion, age-related changes in bone dimension and cellularity seem to significantly affect the internal dose from α and β emitters in the bone and marrow to critical targets, and 223Ra may be a more efficient

Preservation and reactivation of Candidatus Jettenia asiatica and Anammoxoglobus propionicus using different preservative agents.

PubMed

Viancelli, A; Pra, M C; Scussiato, L A; Cantão, M; Ibelli, A M G; Kunz, A

2017-11-01

Anaerobic ammonium oxidation (anammox) bacteria have peculiar characteristics that make them difficult to cultivate. The conservation of these microorganisms in culture collections or laboratories requires successful preservation and reactivation techniques. Furthermore, studies have shown that successful reactivation may be preservative dependent. Considering this, the present study aimed to evaluate the preservation and reactivation of anammox consortia enriched from swine manure treatment lagoons, by using different preservative agents at different temperatures: KNO 3 (at 4 °C), glycerol (-20 °C, -80 °C), and skimmed cow milk (-20 °C, -80 °C, -200 °C). After 4 months, the biomass was thawed (except for KNO 3 ), and the reestablishment of anammox activity was evaluated by stoichiometric coefficients. Microbial community transformation during the reactivation process was also studied by 16S rDNA sequence analysis. The results showed that the anammox biomass preserved with glycerol or skimmed cow milk at -80 °C recovered activity, while the biomass preserved with other methodologies did not reestablish activity during the studied time (90 days). The bacterial community from the biomass with anammox activity was characterized and showed the presence of Candidatus Brocadia anammoxidans, Candidatus Jettenia asiatica, and Candidatus Anammoxoglobus propionicus. Preservation with skimmed cow milk at -80 °C favored the selection of Candidatus Anammoxoglobus propionicus, while preservation with glycerol at -80 °C was successful for Candidatus Jettenia asiatica. The present study was effective on anammox sludge preservation and reactivation using low-cost processes for anammox cultures preservation, which is important for biomass transport and deammonification reactor start up. Copyright © 2017 Elsevier Ltd. All rights reserved.

Vitex agnus castus as prophylaxis for osteopenia after orchidectomy in rats compared with estradiol and testosterone supplementation.

PubMed

Sehmisch, S; Boeckhoff, J; Wille, J; Seidlova-Wuttke, D; Rack, T; Tezval, M; Wuttke, W; Stuermer, K M; Stuermer, E K

2009-06-01

Osteoporosis research undertaken in males is rare and there are only a few therapeutic options. Phytoestrogens might be a safe alternative for prophylaxis. Sixty 3-month-old male rats were orchidectomized and divided into five groups. The groups either received soy-free food (C), estradiol (E), testosterone (T) or Vitex agnus castus in different concentrations (AC high/AC low) for 12 weeks. The tibia metaphysis was tested biomechanically and histomorphometrically. The AC high group reached 87% of the biomechanical values of the estradiol group and was significantly superior to the control group. Testosterone supplementation resulted in poor biomechanical properties. The cortical bone parameters of the AC group were similar to the control group, while supplementation with estradiol and testosterone demonstrated a reduction of cortical bone. The AC high group reached 88.4% of trabecular bone area, 80.7% of trabecular number and 66.9% of the number of trabecular nodes compared with estradiol supplementation. Vitex agnus castus demonstrated osteoprotective effects in males. It preserves the cortical as well as the trabecular bone and might be a safe alternative for HRT. Testosterone supplementation has positive effects on trabecular bone, which are concurrently counteracted by the loss of cortical bone. (c) 2008 John Wiley & Sons, Ltd.

Trabecular meshwork ECM remodeling in glaucoma: could RAS be a target?

PubMed

Agarwal, Puneet; Agarwal, Renu

2018-06-14

Disturbances of extracellular matrix (ECM) homeostasis in trabecular meshwork (TM) cause increased aqueous outflow resistance leading to elevated intraocular pressure (IOP) in glaucomatous eyes. Therefore, restoration of ECM homeostasis is a rational approach to prevent disease progression. Since renin-angiotensin system (RAS) inhibition positively alters ECM homeostasis in cardiovascular pathologies involving pressure and volume overload, it is likely that RAS inhibitors reduce IOP primarily by restoring ECM homeostasis. Areas covered: Current evidence showing the presence of RAS components in ocular tissue and its role in regulating aqueous humor dynamics is briefly summarized. The role of RAS in ECM remodeling is discussed both in terms of its effects on ECM synthesis and its breakdown. The mechanisms of ECM remodeling involving interactions of RAS with transforming growth factor-β, Wnt/β-catenin signaling, bone morphogenic proteins, connective tissue growth factor, and matrix metalloproteinases in ocular tissue are discussed. Expert opinion: Current literature strongly indicates a significant role of RAS in ECM remodeling in TM of hypertensive eyes. Hence, IOP-lowering effect of RAS inhibitors may primarily be attributed to restoration of ECM homeostasis in aqueous outflow pathways rather than its vascular effects. However, the mechanistic targets for RAS inhibitors have much wider distribution and consequences, which remain relatively unexplored in TM.

The intrinsic stiffness of human trabecular meshwork cells increases with senescence

PubMed Central

Chang, Yow-Ren; Murphy, Christopher J.; Russell, Paul

2015-01-01

Dysfunction of the human trabecular meshwork (HTM) plays a central role in the age-associated disease glaucoma, a leading cause of irreversible blindness. The etiology remains poorly understood but cellular senescence, increased stiffness of the tissue, and the expression of Wnt antagonists such as secreted frizzled related protein-1 (SFRP1) have been implicated. However, it is not known if senescence is causally linked to either stiffness or SFRP1 expression. In this study, we utilized in vitro HTM senescence to determine the effect on cellular stiffening and SFRP1 expression. Stiffness of cultured cells was measured using atomic force microscopy and the morphology of the cytoskeleton was determined using immunofluorescent analysis. SFRP1 expression was measured using qPCR and immunofluorescent analysis. Senescent cell stiffness increased 1.88±0.14 or 2.57±0.14 fold in the presence or absence of serum, respectively. This was accompanied by increased vimentin expression, stress fiber formation, and SFRP1 expression. In aggregate, these data demonstrate that senescence may be a causal factor in HTM stiffening and elevated SFRP1 expression, and contribute towards disease progression. These findings provide insight into the etiology of glaucoma and, more broadly, suggest a causal link between senescence and altered tissue biomechanics in aging-associated diseases. PMID:25915531

Dietary acid load, trabecular bone integrity, and mineral density in an ageing population: the Rotterdam study.

PubMed

de Jonge, E A L; Koromani, F; Hofman, A; Uitterlinden, A G; Franco, O H; Rivadeneira, F; Kiefte-de Jong, J C

2017-08-01

We studied the relation between a diet that is high in acid-forming nutrients (e.g. proteins) and low in base-forming nutrients (e.g. potassium) and bone structure. We showed a negative relation, which was more prominent if proteins were of animal rather than of vegetable origin and if intake of dietary fibre was high. Studies on dietary acid load (DAL) and fractures have shown inconsistent results. Associations between DAL, bone mineral density (BMD) and trabecular bone integrity might play a role in these inconsistencies and might be influenced by renal function and dietary fibre intake. Therefore, our aim was to study (1) associations of DAL with BMD and with the trabecular bone score (TBS) and (2) the potential influence of renal function and dietary fibre in these associations. Dutch individuals aged 45 years and over (n = 4672) participating in the prospective cohort of the Rotterdam study were included. Based on food frequency questionnaires, three indices of DAL were calculated: the net endogenous acid production (NEAP) and the ratios of vegetable or animal protein and potassium (VegPro/K and AnPro/K). Data on lumbar spinal TBS and BMD were derived from dual-energy X-ray absorptiometry measurements. Independent of confounders, NEAP and AnPro/K, but not VegPro/K, were associated with low TBS (standardized β (95%) = -0.04 (-0.07, -0.01) and -0.08 (-0.11, -0.04)) but not with BMD. Associations of AnPro/K and VegPro/K with TBS were non-linear and differently shaped. Unfavourable associations between NEAP, BMD and TBS were mainly present in subgroups with high fibre intake. High NEAP was associated with low TBS. Associations of AnPro/K and VegPro/K and TBS were non-linear and differently shaped. No significant associations of DAL with BMD were observed, nor was there any significant interaction between DAL and renal function. Mainly in participants with high intake of dietary fibre, DAL might be detrimental to bone.

Relationship between sample volumes and modulus of human vertebral trabecular bone in micro-finite element analysis.

PubMed

Wen, Xin-Xin; Xu, Chao; Zong, Chun-Lin; Feng, Ya-Fei; Ma, Xiang-Yu; Wang, Fa-Qi; Yan, Ya-Bo; Lei, Wei

2016-07-01

Micro-finite element (μFE) models have been widely used to assess the biomechanical properties of trabecular bone. How to choose a proper sample volume of trabecular bone, which could predict the real bone biomechanical properties and reduce the calculation time, was an interesting problem. Therefore, the purpose of this study was to investigate the relationship between different sample volumes and apparent elastic modulus (E) calculated from μFE model. 5 Human lumbar vertebral bodies (L1-L5) were scanned by micro-CT. Cubic concentric samples of different lengths were constructed as the experimental groups and the largest possible volumes of interest (VOI) were constructed as the control group. A direct voxel-to-element approach was used to generate μFE models and steel layers were added to the superior and inferior surface to mimic axial compression tests. A 1% axial strain was prescribed to the top surface of the model to obtain the E values. ANOVA tests were performed to compare the E values from the different VOIs against that of the control group. Nonlinear function curve fitting was performed to study the relationship between volumes and E values. The larger cubic VOI included more nodes and elements, and more CPU times were needed for calculations. E values showed a descending tendency as the length of cubic VOI decreased. When the volume of VOI was smaller than (7.34mm(3)), E values were significantly different from the control group. The fit function showed that E values approached an asymptotic values with increasing length of VOI. Our study demonstrated that apparent elastic modulus calculated from μFE models were affected by the sample volumes. There was a descending tendency of E values as the length of cubic VOI decreased. Sample volume which was not smaller than (7.34mm(3)) was efficient enough and timesaving for the calculation of E. Copyright © 2016 Elsevier Ltd. All rights reserved.

Preservation Concerns in Construction and Remodeling of Libraries: Planning for Preservation.

ERIC Educational Resources Information Center

Trinkley, Michael

To help libraries and other holdings institutions better incorporate preservation concerns in construction, renovation, and routine maintenance, various techniques are presented that allow preservation concerns to be integrated. The following topics are considered: (1) site selection; (2) design of the building envelope; (3) the library interior;…

Preserve America News

Science.gov Websites

America Grants Save Our History Awards Ceremony Held with Historic Preservation Caucus Texas Heritage , San Diego, California; and, Natchitoches-Cane River Region Heritage Tourism, north-central Louisiana . In the Private Preservation category, The History Channel, Save Our History, an effort that is

A review of the iStent® trabecular micro-bypass stent: safety and efficacy

PubMed Central

Wellik, Sarah R; Dale, Elizabeth A

2015-01-01

There is a significant demand for procedures that can effectively treat glaucoma with low risk and good visual outcomes. To fill this void, procedures termed “minimally invasive glaucoma surgery”, are gaining in popularity. This review will focus on the safety and efficacy of one such minimally invasive glaucoma surgery procedure, the trabecular micro-bypass stent. This stent is intended to lower intraocular pressure by directly cannulating Schlemm’s canal and thereby enhancing aqueous outflow. Recent randomized controlled trials and case series have demonstrated the micro-bypass stent to be a relatively safe procedure, with limited complications and no serious adverse sequelae. The most common complication across all studies was stent obstruction or malposition, which generally did not result in any adverse outcome in vision or pressure control. In addition, increased rates of hypotony, choroidal hemorrhage, or infection were not seen with the micro-bypass stent in comparison to cataract surgery alone. PMID:25931808

Loading simulation of lumbar spine vertebrae during a compression test using the finite elements method and trabecular bone strength properties, determined by means of nanoindentations.

PubMed

Bouzakis, K D; Mitsi, S; Michailidis, N; Mirisidis, I; Mesomeris, G; Maliaris, G; Korlos, A; Kapetanos, G; Antonarakos, P; Anagnostidis, K

2004-06-01

The mechanical strength properties of lumbar spine vertebrae are of great importance in a wide range of applications. Herein, through nanoindentations and appropriate evaluation of the corresponding results, trabecular bone struts stress-strain characteristics can be determined. In the frame of the present paper, an L2 fresh cadaveric vertebra, from which posterior elements were removed, was subjected to compression. With the aid of developed finite elements method based algorithms, the cortical shell and the cancellous core bulk elasticity moduli and stresses were determined, whereas the tested vertebra geometrical model used in these algorithms was considered as having a compound structure, consisting of the cancellous bone surrounded by the cortical shell. Moreover nanoindentations were conducted and an appropriate evaluation method of the obtained results was applied to extract stress-strain curves of individual lumbar spine vertebra trabecular bone struts. These data were used in the mathematical description of the vertebrae compression test. The vertebral cancellous bone structure was simulated by a beam elements network, possessing an equivalent porosity and different stiffnesses in vertical and horizontal direction. Thus, the measured course of the compression load versus the occurring specimen deformation was verified.

Preserve America News

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; the U.S. Departments of Defense, Interior, Agriculture, Commerce, Housing and Urban Development United States Advisory Council on Historic Preservation logo U.S. Department of the Interior seal U.S Department of the Interior (DOI) and the Advisory Council on Historic Preservation (ACHP) have announced the

Preserve America News

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Historic Communities and Tourism at the National Trust Conference Preserve America Affiliate Session New Preserve America News |October 2013 Learn About Historic Communities and Tourism at the National Trust year, we're offering a forum on "Historic Communities and Tourism: How Do We Connect the Dots

The ultrastructural characteristics of porcine hepatocytes donated after cardiac death and preserved with warm machine perfusion preservation.

PubMed

Bochimoto, Hiroki; Matsuno, Naoto; Ishihara, Yo; Shonaka, Tatsuya; Koga, Daisuke; Hira, Yoshiki; Nishikawa, Yuji; Furukawa, Hiroyuki; Watanabe, Tsuyoshi

2017-01-01

The effects of warm machine perfusion preservation of liver grafts donated after cardiac death on the intracellular three-dimensional ultrastructure of the organelles in hepatocytes remain unclear. Here we analyzed comparatively the ultrastructure of the endomembrane systems in porcine hepatocytes under warm ischemia and successive hypothermic and midthermic machine perfusion preservation, a type of the warm machine perfusion. Porcine liver grafts which had a warm ischemia time of 60 minutes were perfused for 4 hours with modified University of Wisconsin gluconate solution. Group A grafts were preserved with hypothermic machine perfusion preservation at 8°C constantly for 4 hours. Group B grafts were preserved with rewarming up to 22°C by warm machine perfusion preservation for 4 hours. An analysis of hepatocytes after 60 minutes of warm ischemia by scanning electron microscope revealed the appearance of abnormal vacuoles and invagination of mitochondria. In the hepatocytes preserved by subsequent hypothermic machine perfusion preservation, strongly swollen mitochondria were observed. In contrast, the warm machine perfusion preservation could preserve the functional appearance of mitochondria in hepatocytes. Furthermore, abundant vacuoles and membranous structures sequestrating cellular organelles like autophagic vacuoles were frequently observed in hepatocytes after warm machine perfusion preservation. In conclusion, the ultrastructure of the endomembrane systems in the hepatocytes of liver grafts changed in accordance with the temperature conditions of machine perfusion preservation. In addition, temperature condition of the machine perfusion preservation may also affect the condition of the hepatic graft attributed to autophagy systems, and consequently alleviate the damage of the hepatocytes.

Influence of Lipophilicity on Drug Partitioning into Sclera, Choroid-Retinal Pigment Epithelium, Retina, Trabecular Meshwork, and Optic Nerve

PubMed Central

Kadam, Rajendra S.

2010-01-01

In vitro bovine eye tissue/phosphate-buffered saline, pH 7.4, partition coefficients (Kt:b), in vitro binding to natural melanin, and in vivo delivery at 1 h after posterior subconjunctival injection in Brown Norway rats were determined for eight β-blockers. The Kt:b was in the order intact tissue, dry weight method ≥ intact tissue, wet weight method corrected for tissue water and drug in tissue water ≫ intact tissue, wet weight method > homogenized tissue. In intact tissue methods, Kt:b followed the order choroid-retinal pigment epithelium (RPE) > trabecular meshwork > retina > sclera ∼ optic nerve; propranolol > betaxolol > pindolol ∼ timolol ∼ metoprolol > sotalol ∼ atenolol ∼ nadolol. Intact tissue, wet weight log (Kt:b) correlated positively with log D for all tissues (R2 of 0.7–0.9). Log (melanin binding capacity) correlated positively with choroid-RPE log (Kt:b) (R2 of 0.5). With an increase in concentration, Kt:b decreased in trabecular meshwork for all β-blockers and for some lipophilic β-blockers in choroid-RPE and sclera. With an increase in drug lipophilicity, in vivo tissue distribution increased in choroid-RPE, iris-ciliary body, sclera, and cornea but exhibited a declining trend in retina, vitreous, and lens. In vitro bovine intact tissue, wet weight Kt:b correlated positively with rat in vivo tissue/vitreous humor distribution for sclera, choroid-RPE, and retina (R2 of 0.985–0.993). In vitro tissue partition coefficients might be useful in predicting in vivo drug distribution after trans-scleral delivery. Less lipophilic solutes exhibiting limited nonproductive binding in choroid-RPE might exhibit greater trans-scleral delivery to the retina and vitreous. PMID:19926800

Are milk and alternatives and fruit and vegetable intakes during adolescence associated with cortical and trabecular bone structure, density, and strength in adulthood?

PubMed

Z Movassagh, E; Kontulainen, S; Baxter-Jones, A D G; Whiting, S; Szafron, M; Papadimitropoulos, M; Vatanparast, H

2017-02-01

We investigated the impact of food group intake during adolescence on bone structure and strength during adulthood. In females, we found a beneficial effect of adolescent milk and alternatives and fruit and vegetable intake on adult radius shaft and distal tibia bone structure, respectively. No association was observed in males. The purpose of this study was to investigate whether adolescents with high intake of milk and alternatives (M&A) or fruit and vegetables (F&V) had better adult bone structure and strength compared to those with low intake levels. We analyzed data from 47 males and 69 females enrolled in the Pediatric Bone Mineral Accrual Study (PBMAS 1991-2011), who had one peripheral quantitative computed tomography scan at age 29 ± 2 years. We measured radius and tibia shaft total area (ToA), cortical area (CoA), cortical content (CoC), cortical density, bone strength (SSI p ), and muscle area, as well as distal radius and tibia ToA, total density, trabecular area, trabecular content, trabecular density, and bone strength (BSI c ). Sequential 24-h recalls were used to assess M&A and F&V intake; participants were grouped for their mean intake during adolescence (low = bottom quartile, moderate = middle quartiles, high = top quartile) and were compared using multivariate analysis of covariance while adjusting for adult height, muscle area, physical activity, energy and calcium intake and adolescent energy intake, and physical activity. Females with high M&A intake compared to low M&A intake group (mean 3.8 vs. 1.3 servings/day, respectively) had greater adult ToA (14 %, p < 0.05), CoA (15 %, p < 0.01), and CoC (16 %, p < 0.01) at radius shaft. Females with moderate F&V intake compared to low F&V intake group (mean 3.7 vs. 2.1 servings/day, respectively) had greater adult ToA (8.5 %, p < 0.05) at distal tibia. Higher intake of M&A or F&V during adolescence had a long-term beneficial effect on bone structure in females

Federal Support for Preserve America

Science.gov Websites

the economic vitality of our communities. "Historic preservation has an important place in America. Preserve America promotes education, historic preservation and economic development while economic engine for the community in which that history took place as more Americans discover and

The non-uniformity of fossil preservation.

PubMed

Holland, Steven M

2016-07-19

The fossil record provides the primary source of data for calibrating the origin of clades. Although minimum ages of clades are given by the oldest preserved fossil, these underestimate the true age, which must be bracketed by probabilistic methods based on multiple fossil occurrences. Although most of these methods assume uniform preservation rates, this assumption is unsupported over geological timescales. On geologically long timescales (more than 10 Myr), the origin and cessation of sedimentary basins, and long-term variations in tectonic subsidence, eustatic sea level and sedimentation rate control the availability of depositional facies that preserve the environments in which species lived. The loss of doomed sediments, those with a low probability of preservation, imparts a secular trend to fossil preservation. As a result, the fossil record is spatially and temporally non-uniform. Models of fossil preservation should reflect this non-uniformity by using empirical estimates of fossil preservation that are spatially and temporally partitioned, or by using indirect proxies of fossil preservation. Geologically, realistic models of preservation will provide substantially more reliable estimates of the origination of clades.This article is part of the themed issue 'Dating species divergences using rocks and clocks'. © 2016 The Author(s).

The non-uniformity of fossil preservation

PubMed Central

2016-01-01

The fossil record provides the primary source of data for calibrating the origin of clades. Although minimum ages of clades are given by the oldest preserved fossil, these underestimate the true age, which must be bracketed by probabilistic methods based on multiple fossil occurrences. Although most of these methods assume uniform preservation rates, this assumption is unsupported over geological timescales. On geologically long timescales (more than 10 Myr), the origin and cessation of sedimentary basins, and long-term variations in tectonic subsidence, eustatic sea level and sedimentation rate control the availability of depositional facies that preserve the environments in which species lived. The loss of doomed sediments, those with a low probability of preservation, imparts a secular trend to fossil preservation. As a result, the fossil record is spatially and temporally non-uniform. Models of fossil preservation should reflect this non-uniformity by using empirical estimates of fossil preservation that are spatially and temporally partitioned, or by using indirect proxies of fossil preservation. Geologically, realistic models of preservation will provide substantially more reliable estimates of the origination of clades. This article is part of the themed issue ‘Dating species divergences using rocks and clocks’. PMID:27325828

Preservative treatments for building components

Treesearch

Stan Lebow

2007-01-01

The wood species most commonly used in construction have little natural durability Thus, they are treated with preservatives when used in conditions that favor biodeterioration. The type of preservative used varies with the type of wood product, exposure condition, and specific agent of deterioration. This paper discusses the characteristics of several preservative...

How rebates, copayments, and administration costs affect the cost-effectiveness of osteoporosis therapies.

PubMed

Ferko, Nicole C; Borisova, Natalie; Airia, Parisa; Grima, Daniel T; Thompson, Melissa F

2012-11-01

Because of rising drug expenditures, cost considerations have become essential, necessitating the requirement for cost-effectiveness analyses for managed care organizations (MCOs). The study objective is to examine the impact of various drug-cost components, in addition to wholesale acquisition cost (WAC), on the cost-effectiveness of osteoporosis therapies. A Markov model of osteoporosis was used to exemplify different drug cost scenarios. We examined the effect of varying rebates for oral bisphosphonates--risedronate and ibandronate--as well as considering the impact of varying copayments and administration costs for intravenous zoledronate. The population modeled was 1,000 American women, > or = 50 years with osteoporosis. Patients were followed for 1 year to reflect an annual budget review of formularies by MCOs. The cost of therapy was based on an adjusted WAC, and is referred to as net drug cost. The total annual cost incurred by an MCO for each drug regimen was calculated using the net drug cost and fracture cost. We estimated cost on a quality adjusted life year (QALY) basis. When considering different rebates, results for risedronate versus ibandronate vary from cost-savings (i.e., costs less and more effective) to approximately $70,000 per QALY. With no risedronate rebate, an ibandronate rebate of approximately 65% is required before cost per QALY surpasses $50,000. With rebates greater than 25% for risedronate, irrespective of ibandronate rebates, results become cost-saving. Results also showed the magnitude of cost savings to the MCO varied by as much as 65% when considering no administration cost and the highest coinsurance rate for zoledronate. Our study showed that cost-effectiveness varies considerably when factors in addition to the WAC are considered. This paper provides recommendations for pharmaceutical manufacturers and MCOs when developing and interpreting such analyses.

Preservative-free versus preserved latanoprost eye drops in patients with open-angle glaucoma or ocular hypertension.

PubMed

Aptel, Florent; Choudhry, Reena; Stalmans, Ingeborg

2016-08-01

This study compared the efficacy, safety, and pharmacokinetics of a preservative-free latanoprost formulation to an established, benzalkonium chloride (BAK) containing formulation for the treatment of open-angle glaucoma or ocular hypertension. This was a phase II, randomized, cross-over, investigator-masked, multi-center, pilot study (NCT01494753). A total of 30 untreated adult patients (aged ≥18 years) with primary open angle glaucoma, pseudo-exfoliative glaucoma, pigmentary glaucoma, or ocular hypertension received either preservative-free or preserved latanoprost once daily in both eyes for 6 weeks, before crossing over to receive the other treatment. Efficacy (intraocular pressure [IOP] at 8 am, midday, 4 pm and 8 pm, and global efficacy assessment by investigator), safety (adverse events, ocular symptoms and global tolerance, slit lamp examination, funduscopy, visual field examination, visual acuity, and heart rate), and pharmacokinetics were assessed at Days 0, 42, and 84. Both treatments resulted in a reduction in IOP that was similar for the preservative-free and the preserved formulation at all time points. Similarly, the overall diurnal reduction was similar in both groups (6.3 mmHg [27.9% reduction] and 6.4 mmHg [28.1% reduction] for preserved and preservative-free latanoprost, respectively). There were no differences in global efficacy assessment or in the safety and tolerance of each treatment. Systemic concentrations of latanoprost were very low; AUC0-30 and Cmax were lower and tmax was longer for preservative-free latanoprost. Preservative-free latanoprost showed similar efficacy at all time points compared to BAK preservative containing formulation, with no difference in tolerance, allowing progression to phase III clinical development.

Assessment of circumferential angle-closure by the iris-trabecular contact index with swept-source optical coherence tomography.

PubMed

Baskaran, Mani; Ho, Sue-Wei; Tun, Tin A; How, Alicia C; Perera, Shamira A; Friedman, David S; Aung, Tin

2013-11-01

To evaluate the diagnostic performance of the iris-trabecular contact (ITC) index, a measure of the degree of angle-closure, using swept-source optical coherence tomography (SSOCT, CASIA SS-1000, Tomey Corporation, Nagoya, Japan) in comparison with gonioscopy. Prospective observational study. A total of 108 normal subjects and 32 subjects with angle-closure. The SSOCT 3-dimensional angle scans, which obtain radial scans for the entire circumference of the angle, were performed under dark conditions and analyzed using customized software by a single examiner masked to the subjects' clinical details. The ITC index was calculated as a percentage of the angle that was closed on SSOCT images. First-order agreement coefficient (AC1) statistics and area under the receiver operating characteristic curve (AUC) analyses were performed for angle-closure on the basis of the ITC index in comparison with gonioscopy. Angle-closure on gonioscopy was defined as nonvisibility of posterior trabecular meshwork for at least 2 quadrants. Agreement of the ITC index with gonioscopically defined angle-closure was assessed using the AC1 statistic. Study subjects were predominantly Chinese (95.7%) and female (70.7%), with a mean age of 59.2 (standard deviation, 8.9) years. The median ITC index was 15.24% for gonioscopically open-angle eyes (n = 108) and 48.5% for closed-angle eyes (n = 32) (P = 0.0001). The agreement for angle-closure based on ITC index cutoffs (>35% and ≥50%) and gonioscopic angle-closure was 0.699 and 0.718, respectively. The AUC for angle-closure detection using the ITC index was 0.83 (95% confidence interval, 0.76-0.89), with an ITC index >35% having a sensitivity of 71.9% and specificity of 84.3%. The ITC index is a summary measure of the circumferential extent of angle-closure as imaged with SSOCT. The index had moderate agreement and good diagnostic performance for angle-closure with gonioscopy as the reference standard. Copyright © 2013 American Academy of

Simulated Space Radiation and Weightlessness: Vascular-Bone Coupling Mechanisms to Preserve Skeletal Health

NASA Technical Reports Server (NTRS)

Alwood, J. S.; Limoli, C. L.; Delp, M. D.; Castillo, A. B.; Globus, R. K.

2012-01-01

Weightlessness causes a cephalad fluid shift and reduction in mechanical stimulation, adversely affecting both cortical and trabecular bone tissue in astronauts. In rodent models of weightlessness, the onset of bone loss correlates with reduced skeletal perfusion, reduced and rarified vasculature and lessened vasodilation, which resembles blood-bone symbiotic events that can occur with fracture repair and aging. These are especially serious risks for long term, exploration class missions when astronauts will face the challenge of increased exposure to space radiation and abrupt transitions between different gravity environments upon arrival and return. Previously, we found using the mouse hindlimb unloading model and exposure to heavy ion radiation, both disuse and irradiation cause an acute bone loss that was associated with a reduced capacity to produce bone-forming osteoblasts from the bone marrow. Together, these findings led us to hypothesize that exposure to space radiation exacerbates weightlessness-induced bone loss and impairs recovery upon return, and that treatment with anti-oxidants may mitigate these effects. The specific aims of this recently awarded grant are to: AIM 1 Determine the functional and structural consequences of prolonged weightlessness and space radiation (simulated spaceflight) for bone and skeletal vasculature in the context of bone cell function and oxidative stress. AIM 2 Determine the extent to which an anti-oxidant protects against weightlessness and space radiation-induced bone loss and vascular dysfunction. AIM 3 Determine how space radiation influences later skeletal and vasculature recovery from prolonged weightlessness and the potential of anti-oxidants to preserve adaptive remodeling.

3D Porous Architecture of Stacks of β-TCP Granules Compared with That of Trabecular Bone: A microCT, Vector Analysis, and Compression Study.

PubMed

Chappard, Daniel; Terranova, Lisa; Mallet, Romain; Mercier, Philippe

2015-01-01

The 3D arrangement of porous granular biomaterials usable to fill bone defects has received little study. Granular biomaterials occupy 3D space when packed together in a manner that creates a porosity suitable for the invasion of vascular and bone cells. Granules of beta-tricalcium phosphate (β-TCP) were prepared with either 12.5 or 25 g of β-TCP powder in the same volume of slurry. When the granules were placed in a test tube, this produced 3D stacks with a high (HP) or low porosity (LP), respectively. Stacks of granules mimic the filling of a bone defect by a surgeon. The aim of this study was to compare the porosity of stacks of β-TCP granules with that of cores of trabecular bone. Biomechanical compression tests were done on the granules stacks. Bone cylinders were prepared from calf tibia plateau, constituted high-density (HD) blocks. Low-density (LD) blocks were harvested from aged cadaver tibias. Microcomputed tomography was used on the β-TCP granule stacks and the trabecular bone cores to determine porosity and specific surface. A vector-projection algorithm was used to image porosity employing a frontal plane image, which was constructed line by line from all images of a microCT stack. Stacks of HP granules had porosity (75.3 ± 0.4%) and fractal lacunarity (0.043 ± 0.007) intermediate between that of HD (respectively 69.1 ± 6.4%, p < 0.05 and 0.087 ± 0.045, p < 0.05) and LD bones (respectively 88.8 ± 1.57% and 0.037 ± 0.014), but exhibited a higher surface density (5.56 ± 0.11 mm(2)/mm(3) vs. 2.06 ± 0.26 for LD, p < 0.05). LP granular arrangements created large pores coexisting with dense areas of material. Frontal plane analysis evidenced a more regular arrangement of β-TCP granules than bone trabecule. Stacks of HP granules represent a scaffold that resembles trabecular bone in its porous microarchitecture.

Microbial control and food Preservation: Theory and practice:Principles of food preservation

USDA-ARS?s Scientific Manuscript database

Food preservation is an action or method used to maintain foods at certain desirable properties or quality to obtain maximum benefit. A good method of food preservation is one that slows down or prevents altogether the action of the agents of spoilage without damaging the food. To achieve this, cert...

Post-consumer use efficacies of preservatives in personal care and topical drug products: relationship to preservative category.

PubMed

Ravita, Timothy D; Tanner, Ralph S; Ahearn, Donald G; Arms, Erin L; Crockett, Patrick W

2009-01-01

Ninety-six used personal care and topical OTC drug items collected from consumers in the USA were examined for the presence of microbial contaminants. Of the eye and face product type containing global preservative chemistries (i.e., acceptable for use in Japan without major restrictions), 55% yielded numbers of microorganisms in excess of 500 CFU/g (P < 0.1814). For the mascara products with global preservative chemistries, 79% yielded numbers of microorganisms in excess of 500 CFU/g (P < 0.024). Products containing global preservative chemistries accounted for 88% (n = 14) of the products that had microbial contents above 10(4) CFU/g (P < 0.001). Prominent contaminants were species of Staphylococcus, Pseudomonas, Klebsiella, Streptococcus, Lactobacillus, Bacillus, Corynebacterium, and yeast. In general, under the stress of consumer use, products preserved with global preservative chemistries did not maintain as adequate preservation as products with non-global preservatives.

A History Worth Preserving

NASA Astrophysics Data System (ADS)

Kelly, Cynthia

2008-04-01

The Manhattan Project transformed the course of American and world history, science, politics and society. If we can read about this in books and watch History Channel documentaries, why do we need to preserve some of the properties of this enormous undertaking? The presentation, ``A History Worth Preserving,'' will address why some of the physical properties need to be preserved and which ones we are struggling to maintain for future generations. The story of this effort begins in 1997 as the Department of Energy was posed to demolish the last remaining Manhattan Project properties at the Los Alamos laboratory. Located deep behind security fences, the ``V Site's'' asbestos-shingled wooden buildings looked like humble garages with over-sized wooden doors. The ``V Site'' properties were almost lost twice, first to bulldozers and then the Cerro Grande fire of 2000. Now, visitors can stand inside the building where J. Robert Oppenheimer and his crew once worked and imagine the Trinity ``gadget'' hanging from its hoist shortly before it ushered in the Atomic Age on July 16, 1945. As Richard Rhodes has commented, we preserve what we value of the physical past because it specifically embodies our social past. But many challenge whether the Manhattan Project properties ought to be preserved. Rather than recognize the Manhattan Project as a great achievement worthy of commemoration, some see it as a regrettable event, producing an instrument to take man's inhumanity to man to extremes. While these divergent views will no doubt persist, the significance of the Manhattan Project in producing the world's first atomic bombs is irrefutable. Preserving some of its tangible remains is essential so that future generations can understand what the undertaking entailed from its humble wooden sheds to enormous first-of-a-kind industrial plants with 125,000 people working in secret and living in frontier-like communities. With continuing pressure for their demolition, what progress has

Biaxial Normal Strength Behavior in the Axial-Transverse Plane for Human Trabecular Bone—Effects of Bone Volume Fraction, Microarchitecture, and Anisotropy

PubMed Central

Sanyal, Arnav; Keaveny, Tony M.

2013-01-01

The biaxial failure behavior of the human trabecular bone, which has potential relevance both for fall and gait loading conditions, is not well understood, particularly for low-density bone, which can display considerable mechanical anisotropy. Addressing this issue, we investigated the biaxial normal strength behavior and the underlying failure mechanisms for human trabecular bone displaying a wide range of bone volume fraction (0.06–0.34) and elastic anisotropy. Micro-computer tomography (CT)-based nonlinear finite element analysis was used to simulate biaxial failure in 15 specimens (5 mm cubes), spanning the complete biaxial normal stress failure space in the axial-transverse plane. The specimens, treated as approximately transversely isotropic, were loaded in the principal material orientation. We found that the biaxial stress yield surface was well characterized by the superposition of two ellipses—one each for yield failure in the longitudinal and transverse loading directions—and the size, shape, and orientation of which depended on bone volume fraction and elastic anisotropy. However, when normalized by the uniaxial tensile and compressive strengths in the longitudinal and transverse directions, all of which depended on bone volume fraction, microarchitecture, and mechanical anisotropy, the resulting normalized biaxial strength behavior was well described by a single pair of (longitudinal and transverse) ellipses, with little interspecimen variation. Taken together, these results indicate that the role of bone volume fraction, microarchitecture, and mechanical anisotropy is mostly accounted for in determining the uniaxial strength behavior and the effect of these parameters on the axial-transverse biaxial normal strength behavior per se is minor. PMID:24121715

Emerging concepts in liver graft preservation

PubMed Central

Bejaoui, Mohamed; Pantazi, Eirini; Folch-Puy, Emma; Baptista, Pedro M; García-Gil, Agustín; Adam, René; Roselló-Catafau, Joan

2015-01-01

The urgent need to expand the donor pool in order to attend to the growing demand for liver transplantation has obliged physicians to consider the use of suboptimal liver grafts and also to redefine the preservation strategies. This review examines the different methods of liver graft preservation, focusing on the latest advances in both static cold storage and machine perfusion (MP). The new strategies for static cold storage are mainly designed to increase the fatty liver graft preservation via the supplementation of commercial organ preservation solutions with additives. In this paper we stress the importance of carrying out effective graft washout after static cold preservation, and present a detailed discussion of the future perspectives for dynamic graft preservation using MP at different temperatures (hypothermia at 4 °C, normothermia at 37 °C and subnormothermia at 20 °C-25 °C). Finally, we highlight some emerging applications of regenerative medicine in liver graft preservation. In conclusion, this review discusses the “state of the art” and future perspectives in static and dynamic liver graft preservation in order to improve graft viability. PMID:25593455

Development and Applications of Porous Tantalum Trabecular Metal Enhanced Titanium Dental Implants

PubMed Central

Bencharit, Sompop; Byrd, Warren C.; Altarawneh, Sandra; Hosseini, Bashir; Leong, Austin; Reside, Glenn; Morelli, Thiago; Offenbacher, Steven

2013-01-01

Statement of Problem Porous tantalum trabecular metal has recently been incorporated in titanium dental implants as a new form of implant surface enhancement. However, there is little information on the applications of this material in implant dentistry. Methods We, therefore review the current literature on the basic science and clinical uses of this material. Results Porous tantalum metal is used to improve the contact between osseous structure and dental implants; and therefore presumably facilitate osseointegration. Success of porous tantalum metal in orthopedic implants led to the incorporation of porous tantalum metal in the design of root-from endosseous titanium implants. The porous tantalum three-dimensional enhancement of titanium dental implant surface allows for combining bone ongrowth together with bone ingrowth, or osseoincorporation. While little is known about the biological aspect of the porous tantalum in the oral cavity, there seems to be several possible advantages of this implant design. This article reviews the biological aspects of porous tantalum enhanced titanium dental implants, in particular the effects of anatomical consideration and oral environment to implant designs. Conclusions We propose here possible clinical situations and applications for this type of dental implant. Advantages and disadvantages of the implants as well as needed future clinical studies are discussed. PMID:23527899

Connective Tissue Growth Factor reporter mice label a subpopulation of mesenchymal progenitor cells that reside in the trabecular bone region.

PubMed

Wang, Wen; Strecker, Sara; Liu, Yaling; Wang, Liping; Assanah, Fayekah; Smith, Spenser; Maye, Peter

2015-02-01

Few gene markers selectively identify mesenchymal progenitor cells inside the bone marrow. We have investigated a cell population located in the mouse bone marrow labeled by Connective Tissue Growth Factor reporter expression (CTGF-EGFP). Bone marrow flushed from CTGF reporter mice yielded an EGFP+ stromal cell population. Interestingly, the percentage of stromal cells retaining CTGF reporter expression decreased with age in vivo and was half the frequency in females compared to males. In culture, CTGF reporter expression and endogenous CTGF expression marked the same cell types as those labeled using Twist2-Cre and Osterix-Cre fate mapping approaches, which previously had been shown to identify mesenchymal progenitors in vitro. Consistent with this past work, sorted CTGF+ cells displayed an ability to differentiate into osteoblasts, chondrocytes, and adipocytes in vitro and into osteoblast, adipocyte, and stromal cell lineages after transplantation into a parietal bone defect. In vivo examination of CTGF reporter expression in bone tissue sections revealed that it marked cells highly localized to the trabecular bone region and was not expressed in the perichondrium or periosteum. Mesenchymal cells retaining high CTGF reporter expression were adjacent to, but distinct from mature osteoblasts lining bone surfaces and endothelial cells forming the vascular sinuses. Comparison of CTGF and Osterix reporter expression in bone tissue sections indicated an inverse correlation between the strength of CTGF expression and osteoblast maturation. Down-regulation of CTGF reporter expression also occurred during in vitro osteogenic differentiation. Collectively, our studies indicate that CTGF reporter mice selectively identify a subpopulation of bone marrow mesenchymal progenitor cells that reside in the trabecular bone region. Copyright © 2014 Elsevier Inc. All rights reserved.

Connective Tissue Growth Factor Reporter Mice Label a Subpopulation of Mesenchymal Progenitor Cells that Reside in the Trabecular Bone Region

PubMed Central

Wang, Wen; Strecker, Sara; Liu, Yaling; Wang, Liping; Assanah, Fayekah; Smith, Spenser; Maye, Peter

2014-01-01

Few gene markers selectively identify mesenchymal progenitor cells inside the bone marrow. We have investigated a cell population located in the mouse bone marrow labeled by Connective Tissue Growth Factor reporter expression (CTGF-EGFP). Bone marrow flushed from CTGF reporter mice yielded an EGFP+ stromal cell population. Interestingly, the percentage of stromal cells retaining CTGF reporter expression decreased with age in vivo and was half the frequency in females compared to males. In culture, CTGF reporter expression and endogenous CTGF expression marked the same cell types as those labeled using Twist2-Cre and Osterix-Cre fate mapping approaches, which previously has been shown to identify mesenchymal progenitors in vitro. Consistent with this past work, sorted CTGF+ cells displayed an ability to differentiate into osteoblasts, chondrocytes, and adipocytes in vitro and into osteoblast, adipocyte, and stromal cell lineages after transplantation into a parietal bone defect. In vivo examination of CTGF reporter expression in bone tissue sections revealed it marked cells highly localized to the trabecular bone region and was not expressed in the perichondrium or periosteum. Mesenchymal cells retaining high CTGF reporter expression were adjacent to, but distinct from mature osteoblasts lining bone surfaces and endothelial cells forming the vascular sinuses. Comparison of CTGF and Osterix reporter expression in bone tissue sections indicated an inverse correlation between the strength of CTGF expression and osteoblast maturation. Down-regulation of CTGF reporter expression also occurred during in vitro osteogenic differentiation. Collectively, our studies indicate that CTGF reporter mice selectively identify a subpopulation of bone marrow mesenchymal progenitor cells that reside in the trabecular bone region. PMID:25464947

Conservation, Preservation, and Digitization.

ERIC Educational Resources Information Center

Lynch, Clifford A.; Brownrigg, Edwin B.

1986-01-01

Digital technologies should be considered a method of preservation for library materials. Current conservation strategies of restoration, deacidification, and microfilming are expensive, and they limit access. Digitization offers improved access while preserving materials and reflects a change in the library role from depository of printed…

Contact sensitivity to preservatives in Singapore: frequency of sensitization to 11 common preservatives 2006-2011.

PubMed

Cheng, Suzanne; Leow, Yung Hian; Goh, Chee Leok; Goon, Anthony

2014-01-01

Preservatives are indispensable agents used to prevent bacterial and fungal contamination of cosmetics, personal care products, domestic preparations, and industrial products. We evaluated patch-test data at the National Skin Centre, Singapore, from 2006 to 2011 to identify the trends in preservative contact allergies. All patients with suspected contact dermatitis were patch tested to 4 preservatives within the modified European standard series. Patients were also tested with 7 preservatives from our special series if clinically indicated. Three thousand one hundred seventy-seven patients were tested to preservatives in the standard series. Sensitization frequencies were all greater than 1%: parabens (2.58%), methylchloroisothiazolinone/methylisothiazolinone (1.75%), quaternium 15 (1.43%), and methyldibromoglutaronitrile (1.2%). There was no change in trends in sensitization frequencies from 2006 to 2011, with no increase in sensitization frequency to methylchloroisothiazolinone/methylisothiazolinone. The sensitization frequencies for methyldibromoglutaronitrile/phenoxyethanol and diazolidinylurea were 2.03% and 1.37%, respectively, and remained less than 1% for bronopol, imidazolidinyl urea, and 2-phenoxyethanol. A rate of 0% was seen for 1,3-dimethylol-5,5-dimethyl hydantoin and formaldehyde; 9.4% of positive patch-test results became positive only at day 7. Preservatives are common causes of allergic contact dermatitis. This should be considered when introducing new preservatives into the market. Day 7 readings are important to detect late reactions.

Preserving Employee Privacy in Wellness.

PubMed

Terry, Paul E

2017-07-01

The proposed "Preserving Employee Wellness Programs Act" states that the collection of information about the manifested disease or disorder of a family member shall not be considered an unlawful acquisition of genetic information. The bill recognizes employee privacy protections that are already in place and includes specific language relating to nondiscrimination based on illness. Why did legislation expressly intending to "preserve wellness programs" generate such antipathy about wellness among journalists? This article argues that those who are committed to preserving employee wellness must be equally committed to preserving employee privacy. Related to this, we should better parse between discussions and rules about commonplace health screenings versus much less common genetic testing.

Data Preservation, Information Preservation, and Lifecyle of Information Management at NASA GES DISC

NASA Technical Reports Server (NTRS)

Khayat, Mo; Kempler, Steve; Deshong, Barbara; Johnson, James; Gerasimov, Irina; Esfandiari, Ed; Berganski, Michael; Wei, Jennifer

2014-01-01

Data lifecycle management awareness is common today; planners are more likely to consider lifecycle issues at mission start. NASA remote sensing missions are typically subject to life cycle management plans of the Distributed Active Archive Center (DAAC), and NASA invests in these national centers for the long-term safeguarding and benefit of future generations. As stewards of older missions, it is incumbent upon us to ensure that a comprehensive enough set of information is being preserved to prevent the risk for information loss. This risk is greater when the original data experts have moved on or are no longer available. Preservation of items like documentation related to processing algorithms, pre-flight calibration data, or input-output configuration parameters used in product generation, are examples of digital artifacts that are sometimes not fully preserved. This is the grey area of information preservation; the importance of these items is not always clear and requires careful consideration. Missing important metadata about intermediate steps used to derive a product could lead to serious challenges in the reproducibility of results or conclusions. Organizations are rapidly recognizing that the focus of life-cycle preservation needs to be enlarged from the strict raw data to the more encompassing arena of information lifecycle management. By understanding what constitutes information, and the complexities involved, we are better equipped to deliver longer lasting value about the original data and derived knowledge (information) from them. The NASA Earth Science Data Preservation Content Specification is an attempt to define the content necessary for long-term preservation. It requires new lifecycle infrastructure approach along with content repositories to accommodate artifacts other than just raw data. The NASA Goddard Earth Sciences Data and Information Services Center (GES DISC) setup an open-source Preservation System capable of long-term archive of

Exercise initiated after the onset of insulin resistance improves trabecular microarchitecture and cortical bone biomechanics of the tibia in hyperphagic Otsuka Long Evans Tokushima Fatty rats.

PubMed

Ortinau, Laura C; Linden, Melissa A; Dirkes, Rebecca K; Rector, R Scott; Hinton, Pamela S

2017-10-01

The present study extends our previous findings that exercise, which prevents the onset of insulin resistance and type 2 diabetes (T2D), also prevents the detrimental effects of T2D on whole-bone and tissue-level strength. Our objective was to determine whether exercise improves bone's structural and material properties if insulin resistance is already present in the Otsuka Long-Evans Tokushima Fatty (OLETF) rat. The OLETF rat is hyperphagic due to a loss-of-function mutation in cholecystokinin-1 receptor (CCK-1 receptor), which leads to progressive obesity, insulin resistance and T2D after the majority of skeletal growth is complete. Because exercise reduces body mass, which is a significant determinant of bone strength, we used a body-mass-matched caloric-restricted control to isolate body-mass-independent effects of exercise on bone. Eight-wk old, male OLETF rats were fed ad libitum until onset of hyperglycemia (20weeks of age), at which time they were randomly assigned to three groups: ad libitum fed, sedentary (O-SED); ad libitum fed, treadmill running (O-EX); or, sedentary, mild caloric restriction to match body mass of O-EX (O-CR). Long-Evans Tokushima Otsuka rats served as the normophagic, normoglycemic controls (L-SED). At 32weeks of age, O-SED rats had T2D as evidenced by hyperglycemia and a significant reduction in fasting insulin compared to OLETFs at 20weeks of age. O-SED rats also had reduced total body bone mineral content (BMC), increased C-terminal telopeptide of type I collagen (CTx)/tartrate resistant acid phosphatase isoform 5b (TRAP5b), decreased N-terminal propeptide of type I procollagen (P1NP), reduced percent cancellous bone volume (BV/TV), trabecular number (Tb.N) and increased trabecular separation (Tb.Sp) and structural model index (SMI) of the proximal tibia compared to L-SED. T2D also adversely affected biomechanical properties of the tibial diaphysis, and serum sclerostin was increased and β-catenin, runt-related transcription factor

Transient Overexpression of Sonic Hedgehog Alters the Architecture and Mechanical Properties of Trabecular Bone

PubMed Central

Kiuru, Maija; Solomon, Jason; Ghali, Bassem; van der Meulen, Marjolein; Crystal, Ronald G; Hidaka, Chisa

2009-01-01

Bone formation and remodeling involve coordinated interactions between osteoblasts and osteoclasts through signaling networks involving a variety of molecular pathways. We hypothesized that overexpression of Sonic hedgehog (Shh), a morphogen with a crucial role in skeletal development, would stimulate osteoblastogenesis and bone formation in adult animals in vivo. Systemic administration of adenovirus expressing the N-terminal form of Shh into adult mice resulted in a primary increase in osteoblasts and their precursors. Surprisingly, however, this was associated with altered trabecular morphology, decreased bone volume, and decreased compressive strength in the vertebrae. Whereas no change was detected in the number of osteoclast precursors, bone marrow stromal cells from Shh-treated mice showed enhanced osteoclastogenic potential in vitro. These effects were mediated by the PTH/PTH-related protein (PTHrP) pathway as evidenced by increased sensitivity to PTH stimulation and upregulation of the PTH/PTHrP receptor (PPR). Together, these data show that Shh has stimulatory effects on osteoprogenitors and osteoblasts in adult animals in vivo, which results in bone remodeling and reduced bone strength because of a secondary increase in osteoclastogenesis. PMID:19338448

Elastic Modulus Determination of Normal and Glaucomatous Human Trabecular Meshwork

PubMed Central

Last, Julie A.; Pan, Tingrui; Ding, Yuzhe; Reilly, Christopher M.; Keller, Kate; Acott, Ted S.; Fautsch, Michael P.; Murphy, Christopher J.; Russell, Paul

2011-01-01

Purpose. Elevated intraocular pressure (IOP) is a risk factor for glaucoma. The principal outflow pathway for aqueous humor in the human eye is through the trabecular meshwork (HTM) and Schlemm's canal (SC). The junction between the HTM and SC is thought to have a significant role in the regulation of IOP. A possible mechanism for the increased resistance to flow in glaucomatous eyes is an increase in stiffness (increased elastic modulus) of the HTM. In this study, the stiffness of the HTM in normal and glaucomatous tissue was compared, and a mathematical model was developed to predict the impact of changes in stiffness of the juxtacanalicular layer of HTM on flow dynamics through this region. Methods. Atomic force microscopy (AFM) was used to measure the elastic modulus of normal and glaucomatous HTM. According to these results, a model was developed that simulated the juxtacanalicular layer of the HTM as a flexible membrane with embedded pores. Results. The mean elastic modulus increased substantially in the glaucomatous HTM (mean = 80.8 kPa) compared with that in the normal HTM (mean = 4.0 kPa). Regional variation was identified across the glaucomatous HTM, possibly corresponding to the disease state. Mathematical modeling suggested an increased flow resistance with increasing HTM modulus. Conclusions. The data indicate that the stiffness of glaucomatous HTM is significantly increased compared with that of normal HTM. Modeling exercises support substantial impairment in outflow facility with increased HTM stiffness. Alterations in the biophysical attributes of the HTM may participate directly in the onset and progression of glaucoma. PMID:21220561

Is My Network Module Preserved and Reproducible?

PubMed Central

Langfelder, Peter; Luo, Rui; Oldham, Michael C.; Horvath, Steve

2011-01-01

In many applications, one is interested in determining which of the properties of a network module change across conditions. For example, to validate the existence of a module, it is desirable to show that it is reproducible (or preserved) in an independent test network. Here we study several types of network preservation statistics that do not require a module assignment in the test network. We distinguish network preservation statistics by the type of the underlying network. Some preservation statistics are defined for a general network (defined by an adjacency matrix) while others are only defined for a correlation network (constructed on the basis of pairwise correlations between numeric variables). Our applications show that the correlation structure facilitates the definition of particularly powerful module preservation statistics. We illustrate that evaluating module preservation is in general different from evaluating cluster preservation. We find that it is advantageous to aggregate multiple preservation statistics into summary preservation statistics. We illustrate the use of these methods in six gene co-expression network applications including 1) preservation of cholesterol biosynthesis pathway in mouse tissues, 2) comparison of human and chimpanzee brain networks, 3) preservation of selected KEGG pathways between human and chimpanzee brain networks, 4) sex differences in human cortical networks, 5) sex differences in mouse liver networks. While we find no evidence for sex specific modules in human cortical networks, we find that several human cortical modules are less preserved in chimpanzees. In particular, apoptosis genes are differentially co-expressed between humans and chimpanzees. Our simulation studies and applications show that module preservation statistics are useful for studying differences between the modular structure of networks. Data, R software and accompanying tutorials can be downloaded from the following webpage: http://www.genetics.ucla.edu/labs/horvath/CoexpressionNetwork/ModulePreservation

Contact dermatitis caused by preservatives.

PubMed

Yim, Elizabeth; Baquerizo Nole, Katherine L; Tosti, Antonella

2014-01-01

Preservatives are biocidal chemicals added to food, cosmetics, and industrial products to prevent the growth of microorganisms. They are usually nontoxic and inexpensive and have a long shelf life. Unfortunately, they commonly cause contact dermatitis. This article reviews the most important classes of preservatives physicians are most likely to encounter in their daily practice, specifically isothiazolinones, formaldehyde and formaldehyde-releasers, iodopropynyl butylcarbamate, methyldibromoglutaronitrile, and parabens. For each preservative mentioned, the prevalence of sensitization, clinical presentation of contact dermatitis, patch testing concentrations, cross reactions, and related legislation will be discussed. Mandatory labeling of preservatives is required in some countries, but not required in others. Until policies are made, physicians and patients must be proactive in identifying potential sensitizers and removing their use. We hope that this article will serve as a guide for policy makers in creating legislation and future regulations on the use and concentration of certain preservatives in cosmetics and industrial products.

Female fertility preservation: a clinical perspective.

PubMed

Pavone, Mary E; Confino, Rafael; Steinberg, Marissa

2016-08-01

For patients with cancer, preserving the ability to start a family at a time of their choosing is especially important and may influence decisions pertaining to cancer treatment. For other women who have delayed childbearing for personal or professional reasons, fertility preservation offers the possibility of having a biological child regardless of age. Though these women may be interested in or benefit from fertility preservation, fertility preservation services remain underutilized. While embryo and oocyte cryopreservation remain the standard strategies for female fertility preservation recommended by the American Society of Reproductive Medicine, the American Society of Clinical Oncology and the European Society of Medical Oncology, other strategies (e.g. pharmacological protection of the ovaries and ovarian tissue cryopreservation) are the subject of increasing research. This review will present new data that have become available over the past few years pertaining to all available methods of fertility preservation.

ACHP | News | Historic Preservation Caucus Sponsors Preserve America

Science.gov Websites

and enjoyment of our priceless cultural and natural heritage. The goals of the initiative include: a , increased local participation in preserving the country's cultural and natural heritage assets, and support

Morphological keys in the differential diagnosis of bladder inverted papilloma. Study of two types, trabecular and glandular.

PubMed

Sabater Marco, Vicente; Navalón Verdejo, Pedro; Morera Faet, Arturo

2012-09-01

Inverted papilloma of the urinary bladder is an uncommon urothelial neoplasm that may be specially difficult to distinguish from urothelial carcinoma. Two patients with obstructive symptoms and hematuria have been studied. In the transurethral resection, accidentally, one showed a papillary lesion in the context of nodular hyperplasia of the prostate, where as the other showed a polypoid tumor of the urinary bladder Histologically, in both cases, a bladder inverted papilloma was demonstrated, originating from the surface transitional epithelium. Basal cells exhibited peripheral palisading pattern in the trabecular form. In the glandular type, Dogiel or umbrella cells into the gland-like structures, were recognized. Immunohistochemical stains for p53 and Ki-67 were negative. Umbrella cells were positive for cytokeratin 20. Two cases of bladder inverted papilloma with relevant morphological aspects are presented, which we consider useful for the differential diagnosis with urothelial carcinoma.

Preservation of the biomedical literature: an overview.

PubMed Central

Byrnes, M M

1989-01-01

The National Library of Medicine began to preserve its collection many years ago. This article presents a brief review of NLM's early conservation and microfilming programs, and describes the current activities of the library's new Preservation Section. Also mentioned are the complementary efforts of NLM staff who are involved in research into electronic imaging and the campaign to increase the use of alkaline paper in medical and scientific publishing. Goals of the National Preservation Plan for the Biomedical Literature are summarized and a report on progress in implementing the plan is provided. Results of the preservation needs assessment described in the accompanying article by Kirkpatrick are briefly analyzed. Recent efforts of the Commission on Preservation and Access, the National Endowment for the Humanities, the Research Libraries Group, and several international associations are described in terms of their potential benefit to preservation of the biomedical literature. The need to monitor new preservation technologies and preserve materials in audiovisual and electronic formats is emphasized. It is argued that with enough coordination, cooperation, and willingness among health sciences libraries to share the costs, the goal of preserving all of the important biomedical literature can be accomplished. PMID:2758180

Cosmetic preservative labelling on the Thai market.

PubMed

Bunyavaree, Monthathip; Kasemsarn, Pranee; Boonchai, Waranya

2016-04-01

Preservatives are added to cosmetics and other consumer products to prevent microbial growth and product degradation. Many cosmetic preservatives are skin sensitizers and frequent causes of contact dermatitis. The use of preservatives may vary by country and/or region, according to legislation, and may be reflected in differences in the prevalence rates of preservative allergy worldwide. To examine the type and frequency of preservative use in cosmetics sold in Thai markets in metropolitan Bangkok, Thailand. Preservatives contained in 1000 different cosmetics sold in Thai markets were documented and analysed, based on the labelling of ingredients. Most of the cosmetic and skincare products sold in Thai markets were international brands, with only a small proportion of cosmetic products being produced in Thailand. International brand cosmetics were more likely to contain non-formaldehyde-releasing preservatives than domestically produced brands. Isothiazolinone-based preservatives, which are responsible for the current increase in the prevalence of contact allergy, were found at a significant frequency in domestically produced, leave-on cosmetic products. Preservatives in cosmetics were significantly different according to source of production and type of cosmetics. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Development and initial validation of a novel smoothed-particle hydrodynamics-based simulation model of trabecular bone penetration by metallic implants.

PubMed

Kulper, Sloan A; Fang, Christian X; Ren, Xiaodan; Guo, Margaret; Sze, Kam Y; Leung, Frankie K L; Lu, William W

2018-04-01

A novel computational model of implant migration in trabecular bone was developed using smoothed-particle hydrodynamics (SPH), and an initial validation was performed via correlation with experimental data. Six fresh-frozen human cadaveric specimens measuring 10 × 10 × 20 mm were extracted from the proximal femurs of female donors (mean age of 82 years, range 75-90, BV/TV ratios between 17.88% and 30.49%). These specimens were then penetrated under axial loading to a depth of 10 mm with 5 mm diameter cylindrical indenters bearing either flat or sharp/conical tip designs similar to blunt and self-tapping cancellous screws, assigned in a random manner. SPH models were constructed based on microCT scans (17.33 µm) of the cadaveric specimens. Two initial specimens were used for calibration of material model parameters. The remaining four specimens were then simulated in silico using identical material model parameters. Peak forces varied between 92.0 and 365.0 N in the experiments, and 115.5-352.2 N in the SPH simulations. The concordance correlation coefficient between experimental and simulated pairs was 0.888, with a 95%CI of 0.8832-0.8926, a Pearson ρ (precision) value of 0.9396, and a bias correction factor Cb (accuracy) value of 0.945. Patterns of bone compaction were qualitatively similar; both experimental and simulated flat-tipped indenters produced dense regions of compacted material adjacent to the advancing face of the indenter, while sharp-tipped indenters deposited compacted material along their peripheries. Simulations based on SPH can produce accurate predictions of trabecular bone penetration that are useful for characterizing implant performance under high-strain loading conditions. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1114-1123, 2018. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

7 CFR 782.14 - Identity preservation.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 7 2010-01-01 2010-01-01 false Identity preservation. 782.14 Section 782.14... § 782.14 Identity preservation. (a) The importer and all subsequent buyers of the imported wheat shall preserve the identity of the Canadian-produced wheat. (b) Canadian-produced wheat may only be commingled...

7 CFR 782.14 - Identity preservation.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 7 Agriculture 7 2013-01-01 2013-01-01 false Identity preservation. 782.14 Section 782.14... § 782.14 Identity preservation. (a) The importer and all subsequent buyers of the imported wheat shall preserve the identity of the Canadian-produced wheat. (b) Canadian-produced wheat may only be commingled...

7 CFR 782.14 - Identity preservation.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 7 Agriculture 7 2012-01-01 2012-01-01 false Identity preservation. 782.14 Section 782.14... § 782.14 Identity preservation. (a) The importer and all subsequent buyers of the imported wheat shall preserve the identity of the Canadian-produced wheat. (b) Canadian-produced wheat may only be commingled...

7 CFR 782.14 - Identity preservation.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 7 Agriculture 7 2011-01-01 2011-01-01 false Identity preservation. 782.14 Section 782.14... § 782.14 Identity preservation. (a) The importer and all subsequent buyers of the imported wheat shall preserve the identity of the Canadian-produced wheat. (b) Canadian-produced wheat may only be commingled...

7 CFR 782.14 - Identity preservation.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 7 Agriculture 7 2014-01-01 2014-01-01 false Identity preservation. 782.14 Section 782.14... § 782.14 Identity preservation. (a) The importer and all subsequent buyers of the imported wheat shall preserve the identity of the Canadian-produced wheat. (b) Canadian-produced wheat may only be commingled...

Data Preservation, Information Preservation, and life-cyle of information management at NASA GES DISC

NASA Astrophysics Data System (ADS)

Khayat, M. G.; Deshong, B.; Esfandiari, A. E.; Gerasimov, I. V.; Johnson, J. E.; Kempler, S. J.; Wei, J. C.

2014-12-01

Data lifecycle management awareness is common today; planners are more likely to consider lifecycle issues at mission start. NASA remote sensing missions are typically subject to life cycle management plans of the Distributed Active Archive Center (DAAC), and NASA invests in these national centers for the long-term safeguarding and benefit of future generations. As stewards of older missions, it is incumbent upon us to ensure that a comprehensive enough set of information is being preserved to prevent the risk for "information loss". This risk is greater when the original data experts have moved on or are no longer available. Preservation of items like documentation related to processing algorithms, pre-flight calibration data, or input/output configuration parameters used in product generation, are examples of digital artifacts that are sometimes not fully preserved. This is the grey area of "information preservation"; the importance of these items is not always clear and requires careful consideration. Missing important "metadata" about intermediate steps used to derive a product could lead to serious challenges in the reproducibility of results or conclusions.Organizations are rapidly recognizing that the focus of life-cycle preservation needs to be enlarged from the strict raw data to the more encompassing arena of "information lifecycle management". By understanding what constitutes information, and the complexities involved, we are better equipped to deliver longer lasting value about the original data and derived knowledge (information) from them. The "NASA Earth Science Data Preservation Content Specification" is an attempt to define the content necessary for long-term preservation. It requires new lifecycle infrastructure approach along with content repositories to accommodate artifacts other than just raw data. The NASA Goddard Earth Sciences Data and Information Services Center (GES DISC) setup an open-source Preservation System capable of long

43 CFR 15.12 - Closing of Preserve.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 43 Public Lands: Interior 1 2012-10-01 2011-10-01 true Closing of Preserve. 15.12 Section 15.12 Public Lands: Interior Office of the Secretary of the Interior KEY LARGO CORAL REEF PRESERVE § 15.12 Closing of Preserve. The Preserve may be closed to public use in the event of emergency conditions...

43 CFR 15.12 - Closing of Preserve.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 43 Public Lands: Interior 1 2014-10-01 2014-10-01 false Closing of Preserve. 15.12 Section 15.12 Public Lands: Interior Office of the Secretary of the Interior KEY LARGO CORAL REEF PRESERVE § 15.12 Closing of Preserve. The Preserve may be closed to public use in the event of emergency conditions...

43 CFR 15.12 - Closing of Preserve.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 43 Public Lands: Interior 1 2013-10-01 2013-10-01 false Closing of Preserve. 15.12 Section 15.12 Public Lands: Interior Office of the Secretary of the Interior KEY LARGO CORAL REEF PRESERVE § 15.12 Closing of Preserve. The Preserve may be closed to public use in the event of emergency conditions...

43 CFR 15.12 - Closing of Preserve.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 43 Public Lands: Interior 1 2011-10-01 2011-10-01 false Closing of Preserve. 15.12 Section 15.12 Public Lands: Interior Office of the Secretary of the Interior KEY LARGO CORAL REEF PRESERVE § 15.12 Closing of Preserve. The Preserve may be closed to public use in the event of emergency conditions...

43 CFR 15.12 - Closing of Preserve.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 43 Public Lands: Interior 1 2010-10-01 2010-10-01 false Closing of Preserve. 15.12 Section 15.12 Public Lands: Interior Office of the Secretary of the Interior KEY LARGO CORAL REEF PRESERVE § 15.12 Closing of Preserve. The Preserve may be closed to public use in the event of emergency conditions...

Playing a Role in Historic Preservation

ERIC Educational Resources Information Center

Gibbs, Hope J.

2005-01-01

Columbia University offered the nation's first degree in historic preservation in the early 1970s. Almost overnight, similar programs began springing up from coast to coast. This was one factor that led the National Trust for Historic Preservation to sponsor a higher education study group to examine preservation academics and make suggestions to…

Preservation Assessment and Disaster Response Plan.

ERIC Educational Resources Information Center

Wisdom, Mark

This paper addresses the preservation needs unique to small libraries, where the majority of special collections exist. A preservation survey of the Herrick Memorial Library (Wellington, OH) was conducted to ascertain the condition of its 45,000 holdings and develop a practical low-cost disaster plan. Using accepted preservation survey criteria,…

Training development for pavement preservation.

DOT National Transportation Integrated Search

2013-05-01

This research project strives to help the Iowa Department of Transportation (DOT) fully achieve the full benefits of pavement : preservation through training on proper selection, design, and application of pavement preservation treatments. In some ca...

22 CFR 98.2 - Preservation of Convention records.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 22 Foreign Relations 1 2010-04-01 2010-04-01 false Preservation of Convention records. 98.2...-CONVENTION RECORD PRESERVATION § 98.2 Preservation of Convention records. Once the Convention has entered into force for the United States, the Secretary and DHS will preserve, or require the preservation of...

Visibility of trabecular meshwork by standard and polarization-sensitive optical coherence tomography

NASA Astrophysics Data System (ADS)

Yasuno, Yoshiaki; Yamanari, Masahiro; Kawana, Keisuke; Miura, Masahiro; Fukuda, Shinichi; Makita, Shuichi; Sakai, Shingo; Oshika, Tetsuro

2010-11-01

Polarization-sensitive optical coherence tomography (PS-OCT) is known to be advantageous because of its additional tissue-specific contrast of the anterior eye. So far, this advantage has been shown only qualitatively. We evaluate the improved visibility afforded by 3-D PS corneal and anterior eye segment OCT (PS-CAS-OCT) in visualizing the trabecular meshwork (TM) based on statistical evidences. A total of 31 normal subjects participated in this study. The anterior eye segments of both the eyes of the subjects are scanned using a custom-made PS-CAS-OCT and the standard-scattering OCT (S-OCT) and polarization-sensitive phase-retardation OCT (P-OCT) images are obtained. Three graders grade the visibility of the TM using a four-leveled grading system. The intergrader agreement, intermodality differences, and interquadrant dependence of visibility are statistically examined. All three of three combinations of graders show substantial agreement in visibility with P-OCT (ρ = 0.74, 0.70, and 0.68, Spearman's correlation), while only one of three shows substantial agreement with S-OCT (ρ = 0.72). Significant dependence of the visibility on the modality (S-OCT versus P-OCT) and quadrants are found by the analysis of variance. A subsequent Wilcoxon signed-rank test reveals significantly improved visibility. PS-CAS-OCT may become a useful tool for screening angle-closure glaucoma.

Home-Made Cost Effective Preservation Buffer Is a Better Alternative to Commercial Preservation Methods for Microbiome Research

PubMed Central

Menke, Sebastian; Gillingham, Mark A. F.; Wilhelm, Kerstin; Sommer, Simone

2017-01-01

The investigation of wildlife gastrointestinal microbiomes by next-generation sequencing approaches is a growing field in microbial ecology and conservation. Such studies often face difficulties in sample preservation if neither freezing facilities nor liquid nitrogen (LQN) are readily available. Thus, in order to prevent microbial community changes because of bacterial growth after sampling, preservation buffers need to be applied to samples. However, the amount of microbial community variation attributable to the different preservation treatments and potentially affecting biological interpretation is hardly known. Here, we sampled feces of 11 sheep (Ovis aries sp.) by using swabs and analyzed the effect of air-drying, an inexpensive self-made nucleic acid preservation buffer (NAP), DNA/RNA Shield™, and RNAlater®, each together with freezing (for 10 days) or storing at room temperature (for 10 days) prior to 16S rRNA gene high-throughput sequencing to determine bacterial communities. Results revealed that the proportions of operational taxonomic units (OTUs) belonging to a bacterial phylum were affected by the preservation treatments, and that alpha diversities [observed OTUs, Shannon index, and phylogenetic diversity (PD)] were lower in all preservation treatments than in samples taken by forensic swabs and immediately frozen which is considered as the favored preservation treatment in the absence of any logistic constraints. Overall, NAP had better preservation qualities than RNAlater® and DNA/RNA Shield™ making this self-made buffer a valuable solution in wildlife microbiome studies. PMID:28197142

Home-Made Cost Effective Preservation Buffer Is a Better Alternative to Commercial Preservation Methods for Microbiome Research.

PubMed

Menke, Sebastian; Gillingham, Mark A F; Wilhelm, Kerstin; Sommer, Simone

2017-01-01

The investigation of wildlife gastrointestinal microbiomes by next-generation sequencing approaches is a growing field in microbial ecology and conservation. Such studies often face difficulties in sample preservation if neither freezing facilities nor liquid nitrogen (LQN) are readily available. Thus, in order to prevent microbial community changes because of bacterial growth after sampling, preservation buffers need to be applied to samples. However, the amount of microbial community variation attributable to the different preservation treatments and potentially affecting biological interpretation is hardly known. Here, we sampled feces of 11 sheep ( Ovis aries sp.) by using swabs and analyzed the effect of air-drying, an inexpensive self-made nucleic acid preservation buffer (NAP), DNA/RNA Shield™, and RNA later ®, each together with freezing (for 10 days) or storing at room temperature (for 10 days) prior to 16S rRNA gene high-throughput sequencing to determine bacterial communities. Results revealed that the proportions of operational taxonomic units (OTUs) belonging to a bacterial phylum were affected by the preservation treatments, and that alpha diversities [observed OTUs, Shannon index, and phylogenetic diversity (PD)] were lower in all preservation treatments than in samples taken by forensic swabs and immediately frozen which is considered as the favored preservation treatment in the absence of any logistic constraints. Overall, NAP had better preservation qualities than RNA later ® and DNA/RNA Shield™ making this self-made buffer a valuable solution in wildlife microbiome studies.

Psychological Counseling of Female Fertility Preservation Patients

PubMed Central

Lawson, Angela K.; Klock, Susan C.; Pavone, Mary Ellen; Hirshfeld-Cytron, Jennifer; Smith, Kristin N.; Kazer, Ralph R.

2015-01-01

Young cancer patients are increasingly interested in preserving their fertility prior to undergoing gonadotoxic therapies. Although the medical safety and treatment protocols for fertility preservation have been well documented, limited research has addressed the emotional issues which arise in fertility preservation patients. We briefly review the literature on the psychosocial issues in adult female fertility preservation treatment and describe our experiences within this patient population patient. Our findings suggest that several important issues to be addressed during the psychological counseling of adult female fertility preservation patients include: 1) pre-existing psychological distress in patients undergoing treatment, 2) choice of fertility preservation strategy in the face of an uncertain relationship future, 3) decision making regarding use of third party reproduction (e.g., sperm/egg donation, gestational surrogacy), 4) treatment expectations regarding pregnancy and miscarriage, 5) ethical issues related to treatment including the creation, cryopreservation, and disposition of embryos/oocytes, and 6) decision regret from patients who declined fertility preservation. PMID:25996581

Setup of a bone aging experimental model in the rabbit comparing changes in cortical and trabecular bone: Morphological and morphometric study in the femur.

PubMed

Pazzaglia, Ugo E; Sibilia, Valeria; Congiu, Terenzio; Pagani, Francesca; Ravanelli, Marco; Zarattini, Guido

2015-07-01

Bone aging was studied in an experimental model (rabbit femur) in three populations aged 0.5, 1.5, and 7.5 years. Cortical bone histology was compared with a data set from a 1.5-month-old population of an earlier published paper. From 0.5-year-old onward, the mean femur length did not increase further. Thereafter, the mean marrow area increased and the cortical area decreased significantly with aging. This was associated with a structural pattern transformation from plexiform to laminar and then Haversian-like type. The distal meta-epiphysis bone trabecular density of the oldest populations also was significantly lower in specific regions of interest (ROI). Percentage sealed primary vascular canals in laminar bone significantly increased with aging without variation of percentage sealed secondary osteons. Remodeling rate reflected by the density of cutting cones did not significantly change among the age populations. These data suggest that laminar bone vascular pattern is more functional in the fast diaphyseal expansion but not much streamlined with the renewal of blood flow during secondary remodeling. Bone aging was characterized by: 1) secondary remodeling subendosteally; 2) increment of sealed primary vascular canals number; 3) increased calcium content of the cortex; 4) cortical and trabecular bone mass loss in specific ROIs. Taken together, the present data may give a morphological and morphometric basis to perform comparative studies on experimental models of osteoporosis in the rabbit. © 2015 Wiley Periodicals, Inc.

Urine Preservative

NASA Technical Reports Server (NTRS)

Smith, Scott M. (Inventor); Nillen, Jeannie (Inventor)

2001-01-01

Disclosed is CPG, a combination of a chlorhexidine salt (such as chlorhexidine digluconate, chlorhexidine diacetate, or chlorhexidine dichloride) and n-propyl gallate that can be used at ambient temperatures as a urine preservative.

Non-destructive elemental analysis of vertebral body trabecular bone using muonic X-rays.

PubMed

Hosoi, Y; Watanabe, Y; Sugita, R; Tanaka, Y; Nagamine, K; Ono, T; Sakamoto, K

1995-12-01

Non-destructive elemental analysis with muonic X-rays was performed on human vertebral bone and lumbar torso phantoms. It can provide quantitative information on all elements in small deep-seated localized volumes. The experiment was carried out using the superconducting muon channel at TRIUMF in Vancouver, Canada and a lithium drifted germanium detector with an active area of 18.5 cm2. The muon channel produced backward-decayed negative muons with wide kinetic energy range from 0.5 to 54.2 MeV. The muon beam was collimated to a diameter of 18 mm. The number of incoming muons was about 4 x 10(6) approximately 5 x 10(7) per data point. In the measurements with human vertebral bones fixed with neutralized formaldehyde, the correlation coefficient between calcium content measured by muons and by atomic absorption analysis was 0.99 and the level of significance was 0.0003. In the measurements with lumbar torso phantoms, the correlation coefficient between calcium content measured by muons and by atomic absorption analysis was 0.99 and the level of significance was 0.02. The results suggest that elemental analysis in vertebral body trabecular bone using muonic X-rays closely correlates with measurements by atomic absorption analysis.

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

PubMed

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

2007-01-01

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

ACHP | Advisory Council on Historic Preservation News

Science.gov Websites

Preserve America Community Blackstone River Valley Towns and Cities Designated Newest Preserve America Understanding Blackstone River Valley Presents 24 Preserve America Community Applications to the ACHP Laura Bush

Fertility preservation: a challenge for IVF-clinics.

PubMed

Dahhan, Taghride; Mol, Femke; Kenter, Gemma G; Balkenende, Eva M E; de Melker, Annemieke A; van der Veen, Fulco; Dancet, Eline A F; Goddijn, Mariëtte

2015-11-01

Acute fertility preservation for women is an interdisciplinary treatment that requires adequate information provision and early referral. This quality management project aimed to improve fertility preservation care by using a practical tool: Strengths, Weaknesses, Opportunities and Threats (SWOT) analysis. Quality management project was executed between May 2011 and July 2013. This project has been executed in a university affiliated IVF-clinic in cooperation with two oncological sites and used a four-step strategy: (1) monitoring baseline referral process, (2) exploring baseline fertility preservation program by Strengths, Weaknesses, Opportunities and Threats' (SWOT)-analysis, (3) setting up a new fertility preservation program and (4) evaluating the new fertility preservation program by means of SWOT-analysis. During the three-months monitoring period, fertility preservation was requested for a total of 126 women. The mean age of the women was 33.8 years old (range 1-42 years old). Most requests came from women who wanted to cryopreserve oocytes because of age-related decline of fertility (n=90; 71%). Most requests for acute fertility preservation concerned women with breast cancer (n=16; 57%). Information leaflets and pre-consultation questionnaires for women improved the quality of first fertility preservation consultation as evaluated by final SWOT-analysis. Collaboration with oncological centres and information about fertility preservation improved the referral process. SWOT-analysis proved useful for setting up a new fertility preservation-program and can be recommended as a tool to improve the management and organisation of new types of reproductive care. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Fertility preservation 2

PubMed Central

De Vos, Michel; Smitz, Johan; Woodruff, Teresa K

2014-01-01

Enhanced long-term survival rates of young women with cancer and advances in reproductive medicine and cryobiology have culminated in an increased interest in fertility preservation methods in girls and young women with cancer. Present data suggest that young patients with cancer should be referred for fertility preservation counselling quickly to help with their coping process. Although the clinical application of novel developments, including oocyte vitrification and oocyte maturation in vitro, has resulted in reasonable success rates in assisted reproduction programmes, experience with these techniques in the setting of fertility preservation is in its infancy. It is hoped that these and other approaches, some of which are still regarded as experimental (eg, ovarian tissue cryopreservation, pharmacological protection against gonadotoxic agents, in-vitro follicle growth, and follicle transplantation) will be optimised and become established within the next decade. Unravelling the complex mechanisms of activation and suppression of follicle growth will not only expand the care of thousands of women diagnosed with cancer, but also inform the care of millions of women confronted with reduced reproductive fitness because of ageing. PMID:25283571

Toward precision medicine for preserving fertility in cancer patients: existing and emerging fertility preservation options for women.

PubMed

Kim, So-Youn; Kim, Seul Ki; Lee, Jung Ryeol; Woodruff, Teresa K

2016-03-01

As the number of young cancer survivors increases, quality of life after cancer treatment is becoming an ever more important consideration. According to a report from the American Cancer Society, approximately 810,170 women were diagnosed with cancer in 2015 in the United States. Among female cancer survivors, 1 in 250 are of reproductive age. Anticancer therapies can result in infertility or sterility and can have long-term negative effects on bone health, cardiovascular health as a result of reproductive endocrine function. Fertility preservation has been identified by many young patients diagnosed with cancer as second only to survival in terms of importance. The development of fertility preservation technologies aims to help patients diagnosed with cancer to preserve or protect their fertility prior to exposure to chemo- or radiation therapy, thus improving their chances of having a family and enhancing their quality of life as a cancer survivor. Currently, sperm, egg, and embryo banking are standard of care for preserving fertility for reproductive-age cancer patients; ovarian tissue cryopreservation is still considered experimental. Adoption and surrogate may also need to be considered. All patients should receive information about the fertility risks associated with their cancer treatment and the fertility preservation options available in a timely manner, whether or not they decide to ultimately pursue fertility preservation. Because of the ever expanding number of options for treating cancer and preserving fertility, there is now an opportunity to take a precision medicine approach to informing patients about the fertility risks associated with their cancer treatment and the fertility preservation options that are available to them.

The 3D-based scaling index algorithm to optimize structure analysis of trabecular bone in postmenopausal women with and without osteoporotic spine fractures

NASA Astrophysics Data System (ADS)

Muller, Dirk; Monetti, Roberto A.; Bohm, Holger F.; Bauer, Jan; Rummeny, Ernst J.; Link, Thomas M.; Rath, Christoph W.

2004-05-01

The scaling index method (SIM) is a recently proposed non-linear technique to extract texture measures for the quantitative characterisation of the trabecular bone structure in high resolution magnetic resonance imaging (HR-MRI). The three-dimensional tomographic images are interpreted as a point distribution in a state space where each point (voxel) is defined by its x, y, z coordinates and the grey value. The SIM estimates local scaling properties to describe the nonlinear morphological features in this four-dimensional point distribution. Thus, it can be used for differentiating between cluster-, rod-, sheet-like and unstructured (background) image components, which makes it suitable for quantifying the microstructure of human cancellous bone. The SIM was applied to high resolution magnetic resonance images of the distal radius in patients with and without osteoporotic spine fractures in order to quantify the deterioration of bone structure. Using the receiver operator characteristic (ROC) analysis the diagnostic performance of this texture measure in differentiating patients with and without fractures was compared with bone mineral density (BMD). The SIM demonstrated the best area under the curve (AUC) value for discriminating the two groups. The reliability of our new texture measure and the validity of our results were assessed by applying bootstrapping resampling methods. The results of this study show that trabecular structure measures derived from HR-MRI of the radius in a clinical setting using a recently proposed algorithm based on a local 3D scaling index method can significantly improve the diagnostic performance in differentiating postmenopausal women with and without osteoporotic spine fractures.

Preservation of food products by irradiation.

PubMed

McGivney, W T

1988-01-01

The use of irradiation to preserve food has the potential to significantly enhance our capacity to maximize the quality and quantity of the food we consume. In a world in which distribution of food occurs across continents and in which malnourished populations are in dire need of basic food products, any safe, effective, and efficient means of preserving food is more than welcome. Irradiation, as a method for food preservation, has been studied for more than 30 years. This discussion focuses on this most recent method for the preservation of food with particular emphasis on its effects on the safety, nutritive, and aesthetic values of the food preserved by irradiation. The use of ionizing radiation as a method to preserve foods is one that has been demonstrated to be effective for a variety of food classes. Irradiation offers a means to decontaminate, disinfest, and retard the spoilage of the food supply. At the same time, it appears that the wholesomeness of these food products is maintained. Nutritive value can be sustained by use of effective doses of radiation. Concerns over the safety of irradiated food are rooted in questions regarding the potential induction of radioactivity, harmful radiolytic products, and pathogenic radiation-resistant or mutant strains of microorganisms. Research findings have allayed concerns over safety. However, more research is necessary to conclusively resolve these safety issues. Food irradiation is a promising technology that has and will contribute to our ability to feed the people of this world. This technology is but one of many available ways to preserve our greatest natural resource, the food supply. Enhancement of the ability to preserve food by irradiation will facilitate the distribution of food from fertile developed regions to the malnourished peoples of underdeveloped countries. It is in diminishing the problem of malnourishment and starvation that irradiation as a means to preserve food may find the greatest acceptance.

A prospective study of mandibular trabecular bone to predict fracture incidence in women: a low-cost screening tool in the dental clinic.

PubMed

Jonasson, Grethe; Sundh, Valter; Ahlqwist, Margareta; Hakeberg, Magnus; Björkelund, Cecilia; Lissner, Lauren

2011-10-01

Bone structure is the key to the understanding of fracture risk. The hypothesis tested in this prospective study is that dense mandibular trabeculation predicts low fracture risk, whereas sparse trabeculation is predictive of high fracture risk. Out of 731 women from the Prospective Population Study of Women in Gothenburg with dental examinations at baseline 1968, 222 had their first fracture in the follow-up period until 2006. Mandibular trabeculation was defined as dense, mixed dense plus sparse, and sparse based on panoramic radiographs from 1968 and/or 1980. Time to fracture was ascertained and used as the dependent variable in three Cox proportional hazards regression analyses. The first analysis covered 12 years of follow-up with self-reported endpoints; the second covered 26 years of follow-up with hospital verified endpoints; and the third combined the two follow-up periods, totaling 38 years. Mandibular trabeculation was the main independent variable predicting incident fractures, with age, physical activity, alcohol consumption and body mass index as covariates. The Kaplan-Meier curve indicated a graded association between trabecular density and fracture risk. During the whole period covered, the hazard ratio of future fracture for sparse trabeculation compared to mixed trabeculation was 2.9 (95% CI: 2.2-3.8, p<0.0001), and for dense versus mixed trabeculation was 0.21 (95% CI: 0.1-0.4, p<0.0001). The trabecular pattern was a highly significant predictor of future fracture risk. Our findings imply that dentists, using ordinary dental radiographs, can identify women at high risk for future fractures at 38-54 years of age, often long before the first fracture occurs. Copyright © 2011 Elsevier Inc. All rights reserved.

Aging Versus Postmenopausal Osteoporosis: Bone Composition and Maturation Kinetics at Actively-Forming Trabecular Surfaces of Female Subjects Aged 1 to 84 Years.

PubMed

Paschalis, Eleftherios P; Fratzl, Peter; Gamsjaeger, Sonja; Hassler, Norbert; Brozek, Wolfgang; Eriksen, Erik F; Rauch, Frank; Glorieux, Francis H; Shane, Elizabeth; Dempster, David; Cohen, Adi; Recker, Robert; Klaushofer, Klaus

2016-02-01

Bone strength depends on the amount of bone, typically expressed as bone mineral density (BMD), determined by dual-energy X-ray absorptiometry (DXA), and on bone quality. Bone quality is a multifactorial entity including bone structural and material compositional properties. The purpose of the present study was to examine whether bone material composition properties at actively-forming trabecular bone surfaces in health are dependent on subject age, and to contrast them with postmenopausal osteoporosis patients. To achieve this, we analyzed by Raman microspectroscopy iliac crest biopsy samples from healthy subjects aged 1.5 to 45.7 years, paired biopsy samples from females before and immediately after menopause aged 46.7 to 53.6 years, and biopsy samples from placebo-treated postmenopausal osteoporotic patients aged 66 to 84 years. The monitored parameters were as follows: the mineral/matrix ratio; the mineral maturity/crystallinity (MMC); nanoporosity; the glycosaminoglycan (GAG) content; the lipid content; and the pyridinoline (Pyd) content. The results indicate that these bone quality parameters in healthy, actively-forming trabecular bone surfaces are dependent on subject age at constant tissue age, suggesting that with advancing age the kinetics of maturation (either accumulation, or posttranslational modifications, or both) change. For most parameters, the extrapolation of models fitted to the individual age dependence of bone in healthy individuals was in rough agreement with their values in postmenopausal osteoporotic patients, except for MMC, lipid, and Pyd content. Among these three, Pyd content showed the greatest deviation between healthy aging and disease, highlighting its potential to be used as a discriminating factor. © 2015 American Society for Bone and Mineral Research.

Toward precision medicine for preserving fertility in cancer patients: existing and emerging fertility preservation options for women

PubMed Central

Woodruff, Teresa K.

2016-01-01

As the number of young cancer survivors increases, quality of life after cancer treatment is becoming an ever more important consideration. According to a report from the American Cancer Society, approximately 810,170 women were diagnosed with cancer in 2015 in the United States. Among female cancer survivors, 1 in 250 are of reproductive age. Anticancer therapies can result in infertility or sterility and can have long-term negative effects on bone health, cardiovascular health as a result of reproductive endocrine function. Fertility preservation has been identified by many young patients diagnosed with cancer as second only to survival in terms of importance. The development of fertility preservation technologies aims to help patients diagnosed with cancer to preserve or protect their fertility prior to exposure to chemo- or radiation therapy, thus improving their chances of having a family and enhancing their quality of life as a cancer survivor. Currently, sperm, egg, and embryo banking are standard of care for preserving fertility for reproductive-age cancer patients; ovarian tissue cryopreservation is still considered experimental. Adoption and surrogate may also need to be considered. All patients should receive information about the fertility risks associated with their cancer treatment and the fertility preservation options available in a timely manner, whether or not they decide to ultimately pursue fertility preservation. Because of the ever expanding number of options for treating cancer and preserving fertility, there is now an opportunity to take a precision medicine approach to informing patients about the fertility risks associated with their cancer treatment and the fertility preservation options that are available to them. PMID:26768785

ACHP | Federal Emergency Management Agency Historic Preservation Program

Science.gov Websites

and Historic Preservation Review: https://www.fema.gov/fema-activities-may-trigger-environmental -historic-review FEMA's Environmental & Historic Preservation Guidance for Grant Applicants: http Historic Preservation Review: http://www.fema.gov/environmental-planning-and-historic-preservation-program

76 FR 74721 - Preserving the Open Internet

Federal Register 2010, 2011, 2012, 2013, 2014

2011-12-01

...; Report No. 2936] Preserving the Open Internet AGENCY: Federal Communications Commission. ACTION: Final... for broadband service to preserve and reinforce Internet freedom and openness. DATES: Oppositions to... applicability. Subject: In the Matter of Preserving the Open Internet, Broadband Industry Practices, published...

A comparison of preservative-free diclofenac and preserved diclofenac eye drops after cataract surgery in patients with diabetic retinopathy.

PubMed

Yasuda, Kanako; Miyazawa, Akiko; Shimura, Masahiko

2012-06-01

The aim of this study was to compare the anti-inflammatory efficacy of preservative-free and preserved 0.1% diclofenac eye drops for the management of postoperative inflammation after cataract surgery in patients with nonproliferative diabetic retinopathy and in normal controls. Forty-two diabetic patients and 50 normal control patients who underwent small-incision phacoemulsification cataract surgery bilaterally received topical preservative-free diclofenac in 1 eye and preserved diclofenac in the other eye. The corrected distance visual acuity (CDVA) as determined by a logarithm of the minimum angle of resolution (logMAR) chart, intraocular pressure (IOP), foveal thickness (FT) using optical coherence tomography (OCT), and the anterior chamber flare (ACF) score measured with a laser flare cell meter were monitored for 12 weeks after surgery. In the eyes with diabetic retinopathy, there were no significant differences in CDVA, IOP, FT, and ACF score between the right and left eyes at the initial exam. After cataract surgery, changes in CDVA, IOP, and FT were not influenced by the preservative in the diclofenac eye drops. In contrast, the ACF score in the eyes treated with preserved diclofenac showed slower recovery from postoperative inflammation than the eyes treated with preservative-free diclofenac. In the normal control eyes, similar but milder changes were observed in each of the clinical parameters. Because preservative suppressed the anti-inflammatory efficacy of topical diclofenac after cataract surgery, preservative-free diclofenac may have an improved safety profile during postoperative treatment, especially in patients with diabetic retinopathy.

ACHP | Tribal Historic Preservation Officers

Science.gov Websites

tribes to take on more formal responsibility for the preservation of significant historic properties on preservation of significant historic properties. Those functions include identifying and maintaining inventories of culturally significant properties, nominating properties to national and tribal registers of

Switching from a preserved to a preservative-free prostaglandin preparation in topical glaucoma medication.

PubMed

Uusitalo, Hannu; Chen, Enping; Pfeiffer, Norbert; Brignole-Baudouin, Françoise; Kaarniranta, Kai; Leino, Markku; Puska, Päivi; Palmgren, Elina; Hamacher, Thomas; Hofmann, Günter; Petzold, Gernot; Richter, Ulrich; Riedel, Tobias; Winter, Martin; Ropo, Auli

2010-05-01

The purpose of this study was to investigate the tolerability and intraocular pressure (IOP) reducing effect of the first preservative-free prostaglandin tafluprost (Taflotan) in patients exhibiting ocular surface side-effects during latanoprost (Xalatan) treatment. A total of 158 patients were enrolled in this open-label multicentre study. Eligible patients had to have at least two ocular symptoms, or one sign and one symptom, during treatment with latanoprost. At baseline, the patients were directly switched from latanoprost to preservative-free tafluprost for 12 weeks. The patients were queried for ocular symptoms, and ocular signs were assessed by using tear break-up time, Schirmer's test, fluorescein staining and evaluation of conjunctival hyperaemia and blepharitis. In addition, HLA-DR and MUC5AC in conjunctival impression cytology specimens were analyzed, and a drop discomfort/quality of life (QoL) questionnaire was employed. IOP was measured at all visits. Preservative-free tafluprost maintained IOP at the same level after 12- weeks treatment (16.4 +/- 2.7 mmHg) as latanoprost at baseline (16.8 +/- 2.5 mmHg). During treatment with preservative-free tafluprost, the number of patients having irritation/burning/stinging (56.3%), itching (46.8%), foreign body sensation (49.4%), tearing (55.1%) and dry eye sensation (64.6%) decreased to 28.4%, 26.5%, 27.1%, 27.1% and 39.4% correspondingly. The number of the patients with abnormal fluorescein staining of cornea (81.6%) and conjunctiva (84.2%), blepharitis (60.1%), conjunctival hyperaemia (84.2%) and abnormal Schirmer's test (71.5%) was also reduced significantly to 40.6%, 43.2%, 40.6%, 60.0% and 59.4% correspondingly. The tear break-up time improved significantly from 4.5 +/- 2.5 seconds to 7.8 +/- 4.9 seconds. A reduction in the number of patients with abnormal conjunctival cells based on HLA-DR and MUC5AC was also detected. Preservative-free tafluprost maintained IOP at the same level as latanoprost, but was

Prospective Evaluation of Two iStent® Trabecular Stents, One iStent Supra® Suprachoroidal Stent, and Postoperative Prostaglandin in Refractory Glaucoma: 4-year Outcomes.

PubMed

Myers, Jonathan S; Masood, Imran; Hornbeak, Dana M; Belda, Jose I; Auffarth, Gerd; Jünemann, Anselm; Giamporcaro, Jane Ellen; Martinez-de-la-Casa, Jose M; Ahmed, Iqbal Ike K; Voskanyan, Lilit; Katz, L Jay

2018-03-01

This study evaluates long-term outcomes of two trabecular micro-bypass stents, one suprachoroidal stent, and postoperative prostaglandin in eyes with refractory open angle glaucoma (OAG). Prospective ongoing 5-year study of 80 eligible subjects (70 with 4-year follow-up) with OAG and IOP ≥ 18 mmHg after prior trabeculectomy and while taking 1-3 glaucoma medications. Subjects received two iStent ® trabecular micro-bypass stents, one iStent Supra ® suprachoroidal stent, and postoperative travoprost. Postoperative IOP was measured with medication and annually following medication washouts. Performance was measured by the proportion of eyes with ≥ 20% IOP reduction on one medication (the protocol-specified prostaglandin) versus preoperative medicated IOP (primary outcome); and the proportion of eyes with postoperative IOP ≤ 15 and ≤ 18 mmHg on one medication (secondary outcome). Additional clinical and safety data included medications, visual field, pachymetry, gonioscopy, adverse events, visual acuity, and slit-lamp and fundus examinations. Preoperatively, mean medicated IOP was 22.0 ± 3.1 mmHg on 1.2 ± 0.4 medications, and mean unmedicated IOP was 26.4 ± 2.4 mmHg. Postoperatively, among eyes without later cataract surgery, mean medicated IOP at all visits through 48 months was ≤ 13.7 mmHg (≥ 37% reduction), and annual unmedicated IOP was ≤ 18.4 mmHg (reductions of ≥ 30% vs. preoperative unmedicated IOP and ≥ 16% vs. preoperative medicated IOP). At all postoperative visits among eyes without additional surgery or medication, ≥ 91% of eyes had ≥ 20% IOP reduction on one medication versus preoperative medicated IOP. At month 48, 97 and 98% of eyes achieved IOP ≤ 15 and ≤ 18 mmHg, respectively, on one medication. Six eyes required additional medication, no eyes required additional glaucoma surgery, and safety measurements were favorable throughout follow-up. IOP control was achieved safely with two

12 CFR 741.215 - Records preservation program.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 12 Banks and Banking 6 2010-01-01 2010-01-01 false Records preservation program. 741.215 Section... Unions That Also Apply to Federally Insured State-Chartered Credit Unions § 741.215 Records preservation... preservation program as prescribed by part 749 of this chapter. ...

Preservation of Newspapers: Theoretical Approaches and Practical Achievements

ERIC Educational Resources Information Center

Hasenay, Damir; Krtalic, Maja

2010-01-01

The preservation of newspapers is the main topic of this paper. A theoretical overview of newspaper preservation is given, with an emphasis on the importance of a systematic and comprehensive approach. Efficient newspaper preservation implies understanding the meaning of preservation in general, as well as understanding specific approaches,…

Resveratrol nanosuspensions: interaction of preservatives with nanocrystal production.

PubMed

Kobierski, S; Ofori-Kwakye, K; Müller, R H; Keck, C M

2011-12-01

The effect of six different preservatives on the production process and stability of resveratrol nanosuspensions was investigated. Nanosuspensions of the anti-oxidant resveratrol were prepared by high pressure homogenization (1,500 bar, 20 homogenization cycles). The preservatives used were: caprylyl glycol (0.75%), Euxyl PE 9010 (1.0%), Hydrolite-5 (2.0), Phenonip (0.75%), Rokonsal PB-5 (0.5%) and MultiEx Naturotics (2.0%). Preservation is essential for oral and dermal nanosuspensions, but can impair the stability. The effect of the preservatives on stability as a function of cycle numbers was determined by size measurements (photon correlation spectroscopy (PCS), laser diffraction (LD) and light microscopy). Zeta potential measurements were performed for determination of the Stern potential (measurements in water) and as stability criterion (measurements in original dispersion medium), to elucidate the mechanism of destabilization. The preservatives could be placed into three groups. Hydrolite-5 did not affect the production process and the short term stability, sizes were practically identical to the preservative-free nanosuspension (e.g. PCS diameters 196 nm and 184 nm, respectively). All other preservatives impaired the stability medium to pronounced, being most pronounced for MultiEx Naturotics. Hydrolite-5 is recommended as preservative of choice. A mechanistic model was developed to explain the absence and the different degrees of destabilization. In general, when screening for suitable preservatives, suspensions are produced, different preservatives added and the size changes are monitored over long-term. The destabilizing effect of the preservatives on nanosuspensions became evident when added in the production process immediately, thus this can be used as a screening tool for optimal, non-destabilizing preservatives, replacing or minimizing time-consuming long-term stability studies.

Prevalence of ocular symptoms and signs with preserved and preservative free glaucoma medication

PubMed Central

Pisella, P J; Pouliquen, P; Baudouin, C

2002-01-01

Aim: To determine the incidence of ocular toxicity of preservatives with glaucoma medications. Methods: A prospective epidemiological survey was carried out in 1999 by 249 ophthalmologists on 4107 patients. Ocular symptoms, conjunctiva, cornea, and eyelids were assessed. A χ2 test was used for differences between preserved eye drops (P) and preservative free eye drops (PF). Results: 84% patients used P, 13% received PF, and 3% a combination of P and PF eye drops. All symptoms were more prevalent with P than with PF drops (p<0.001): discomfort upon instillation (43% versus 17%), and symptoms between instillations such as burning-stinging (40% versus 22%), foreign body sensation (31% versus 14%), dry eye sensation (23% versus 14%), tearing (21% versus 14%), and eyelid itching (18% versus 10%). An increased incidence (>2 times) of ocular signs was seen with P eye drops. The prevalence of signs and symptoms was dose dependent, increasing with the number of P drops. A reduction in the symptoms and signs was observed when patients changed from P to PF eye drops (p<0.001). Conclusions: Symptoms and signs are less prevalent when PF drops are used. Moreover, most of the adverse reactions induced by P glaucoma medication are reversible after removing preservatives. PMID:11914211

28 CFR 36.405 - Alterations: Historic preservation.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 28 Judicial Administration 1 2010-07-01 2010-07-01 false Alterations: Historic preservation. 36... Alterations: Historic preservation. (a) Alterations to buildings or facilities that are eligible for listing in the National Register of Historic Places under the National Historic Preservation Act (16 U.S.C...

28 CFR 701.17 - Preservation of records.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 28 Judicial Administration 2 2010-07-01 2010-07-01 false Preservation of records. 701.17 Section 701.17 Judicial Administration OFFICE OF INDEPENDENT COUNSEL PROCEDURES FOR DISCLOSURE OF RECORDS UNDER THE FREEDOM OF INFORMATION ACT § 701.17 Preservation of records. The Office shall preserve all...

Direct estimation of human trabecular bone stiffness using cone beam computed tomography.

PubMed

Klintström, Eva; Klintström, Benjamin; Pahr, Dieter; Brismar, Torkel B; Smedby, Örjan; Moreno, Rodrigo

2018-04-10

The aim of this study was to evaluate the possibility of estimating the biomechanical properties of trabecular bone through finite element simulations by using dental cone beam computed tomography data. Fourteen human radius specimens were scanned in 3 cone beam computed tomography devices: 3-D Accuitomo 80 (J. Morita MFG., Kyoto, Japan), NewTom 5 G (QR Verona, Verona, Italy), and Verity (Planmed, Helsinki, Finland). The imaging data were segmented by using 2 different methods. Stiffness (Young modulus), shear moduli, and the size and shape of the stiffness tensor were studied. Corresponding evaluations by using micro-CT were regarded as the reference standard. The 3-D Accuitomo 80 (J. Morita MFG., Kyoto, Japan) showed good performance in estimating stiffness and shear moduli but was sensitive to the choice of segmentation method. NewTom 5 G (QR Verona, Verona, Italy) and Verity (Planmed, Helsinki, Finland) yielded good correlations, but they were not as strong as Accuitomo 80 (J. Morita MFG., Kyoto, Japan). The cone beam computed tomography devices overestimated both stiffness and shear compared with the micro-CT estimations. Finite element-based calculations of biomechanics from cone beam computed tomography data are feasible, with strong correlations for the Accuitomo 80 scanner (J. Morita MFG., Kyoto, Japan) combined with an appropriate segmentation method. Such measurements might be useful for predicting implant survival by in vivo estimations of bone properties. Copyright © 2018 Elsevier Inc. All rights reserved.

Federal Support for Preserve America

Science.gov Websites

Development logo Mrs. Laura Bush Presents "Preserve America History Teacher of the Year" Award to , West Virginia, the 2006 "Preserve America History Teacher of the Year" Award during a ceremony held at Lincoln Hall in The Union League Club. "Great history teachers take required

Image segmentation on adaptive edge-preserving smoothing

NASA Astrophysics Data System (ADS)

He, Kun; Wang, Dan; Zheng, Xiuqing

2016-09-01

Nowadays, typical active contour models are widely applied in image segmentation. However, they perform badly on real images with inhomogeneous subregions. In order to overcome the drawback, this paper proposes an edge-preserving smoothing image segmentation algorithm. At first, this paper analyzes the edge-preserving smoothing conditions for image segmentation and constructs an edge-preserving smoothing model inspired by total variation. The proposed model has the ability to smooth inhomogeneous subregions and preserve edges. Then, a kind of clustering algorithm, which reasonably trades off edge-preserving and subregion-smoothing according to the local information, is employed to learn the edge-preserving parameter adaptively. At last, according to the confidence level of segmentation subregions, this paper constructs a smoothing convergence condition to avoid oversmoothing. Experiments indicate that the proposed algorithm has superior performance in precision, recall, and F-measure compared with other segmentation algorithms, and it is insensitive to noise and inhomogeneous-regions.

Fertility preservation in Turner syndrome.

PubMed

Grynberg, Michaël; Bidet, Maud; Benard, Julie; Poulain, Marine; Sonigo, Charlotte; Cédrin-Durnerin, Isabelle; Polak, Michel

2016-01-01

Premature ovarian insufficiency is a relatively rare condition that can appear early in life. In a non-negligible number of cases the ovarian dysfunction results from genetic diseases. Turner syndrome (TS), the most common sex chromosome abnormality in females, is associated with an inevitable premature exhaustion of the follicular stockpile. The possible or probable infertility is a major concern for TS patients and their parents, and physicians are often asked about possible options to preserve fertility. Unfortunately, there are no recommendations on fertility preservation in this group. The severely reduced follicle pool even during prepubertal life represents the major limit for fertility preservation and is the root of numerous questions regarding the competence of gametes or ovarian tissue crybanked. In addition, patients suffering from TS show higher than usual rates of spontaneous abortion, fetal anomaly, and maternal morbidity and mortality, which should be considered at the time of fertility preservation and before reutilization of the cryopreserved gametes. Apart from fulfillment of the desire of becoming genetic parents, TS patients may be potential candidates for egg donation, gestational surrogacy, and adoption. The present review discusses the different options for preserving female fertility in TS and the ethical questions raised by these approaches. Copyright © 2016 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

Recent trends in preservative treatments for timber bridges

Treesearch

James P. Wacker

2004-01-01

An overview of wood preservatives currently used for timber bridges is presented through a series of case studies from different regions of the United States. New wood species and preservative treatment options for timber bridges have made choosing the appropriate preservative more complicated. The compatibility of wood species and preservative treatment is often...

Guide for Use of Wood Preservatives in Historic Structures

Treesearch

Stan Lebow; Ronald W. Anthony

2012-01-01

This document provides guidance on wood preservation options in the context of historic preservation. Preserving wooden building materials is critical to historic preservation practitioners. Biodeterioration can be minimized through design, construction practices, maintenance, and, if necessary, by use of wood preservatives. Moisture is the primary cause of...

28 CFR 700.19 - Preservation of records.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 28 Judicial Administration 2 2010-07-01 2010-07-01 false Preservation of records. 700.19 Section 700.19 Judicial Administration OFFICE OF INDEPENDENT COUNSEL PRODUCTION OR DISCLOSURE OF MATERIAL OR... the Privacy Act of 1974 § 700.19 Preservation of records. The Office shall preserve all correspondence...

7 CFR 1.24 - Preservation of records.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 1 2010-01-01 2010-01-01 false Preservation of records. 1.24 Section 1.24 Agriculture Office of the Secretary of Agriculture ADMINISTRATIVE REGULATIONS Official Records § 1.24 Preservation of records. Agencies shall preserve all correspondence relating to the requests it receives under this...

4 CFR 201.15 - Preservation of records.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 4 Accounts 1 2010-01-01 2010-01-01 false Preservation of records. 201.15 Section 201.15 Accounts RECOVERY ACCOUNTABILITY AND TRANSPARENCY BOARD PUBLIC INFORMATION AND REQUESTS § 201.15 Preservation of records. The Board shall preserve all correspondence pertaining to the requests that it receives under...

33 CFR 144.01-20 - Life preservers.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Life preservers. 144.01-20...) OUTER CONTINENTAL SHELF ACTIVITIES LIFESAVING APPLIANCES Manned Platforms § 144.01-20 Life preservers. (a) An approved life preserver shall be provided for each person on a manned platform. The life...

33 CFR 144.01-20 - Life preservers.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Life preservers. 144.01-20...) OUTER CONTINENTAL SHELF ACTIVITIES LIFESAVING APPLIANCES Manned Platforms § 144.01-20 Life preservers. (a) An approved life preserver shall be provided for each person on a manned platform. The life...

6 CFR 5.10 - Preservation of records.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 6 Domestic Security 1 2010-01-01 2010-01-01 false Preservation of records. 5.10 Section 5.10 Domestic Security DEPARTMENT OF HOMELAND SECURITY, OFFICE OF THE SECRETARY DISCLOSURE OF RECORDS AND INFORMATION Freedom of Information Act § 5.10 Preservation of records. Each component shall preserve all...

6 CFR 5.28 - Preservation of records.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 6 Domestic Security 1 2010-01-01 2010-01-01 false Preservation of records. 5.28 Section 5.28 Domestic Security DEPARTMENT OF HOMELAND SECURITY, OFFICE OF THE SECRETARY DISCLOSURE OF RECORDS AND INFORMATION Privacy Act § 5.28 Preservation of records. Each component will preserve all correspondence...

7 CFR 1.24 - Preservation of records.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 7 Agriculture 1 2013-01-01 2013-01-01 false Preservation of records. 1.24 Section 1.24 Agriculture Office of the Secretary of Agriculture ADMINISTRATIVE REGULATIONS Official Records § 1.24 Preservation of records. Agencies shall preserve all correspondence relating to the requests it receives under this...

10 CFR 1303.115 - Preservation of records.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 4 2010-01-01 2010-01-01 false Preservation of records. 1303.115 Section 1303.115 Energy NUCLEAR WASTE TECHNICAL REVIEW BOARD PUBLIC INFORMATION AND REQUESTS § 1303.115 Preservation of records. The Board shall preserve all correspondence pertaining to the requests that it receives under this...

10 CFR 1303.115 - Preservation of records.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 4 2012-01-01 2012-01-01 false Preservation of records. 1303.115 Section 1303.115 Energy NUCLEAR WASTE TECHNICAL REVIEW BOARD PUBLIC INFORMATION AND REQUESTS § 1303.115 Preservation of records. The Board shall preserve all correspondence pertaining to the requests that it receives under this...

10 CFR 1303.115 - Preservation of records.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 4 2014-01-01 2014-01-01 false Preservation of records. 1303.115 Section 1303.115 Energy NUCLEAR WASTE TECHNICAL REVIEW BOARD PUBLIC INFORMATION AND REQUESTS § 1303.115 Preservation of records. The Board shall preserve all correspondence pertaining to the requests that it receives under this...

10 CFR 1303.115 - Preservation of records.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 4 2011-01-01 2011-01-01 false Preservation of records. 1303.115 Section 1303.115 Energy NUCLEAR WASTE TECHNICAL REVIEW BOARD PUBLIC INFORMATION AND REQUESTS § 1303.115 Preservation of records. The Board shall preserve all correspondence pertaining to the requests that it receives under this...

10 CFR 1303.115 - Preservation of records.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 4 2013-01-01 2013-01-01 false Preservation of records. 1303.115 Section 1303.115 Energy NUCLEAR WASTE TECHNICAL REVIEW BOARD PUBLIC INFORMATION AND REQUESTS § 1303.115 Preservation of records. The Board shall preserve all correspondence pertaining to the requests that it receives under this...

DNA preservation in silk.

PubMed

Liu, Yawen; Zheng, Zhaozhu; Gong, He; Liu, Meng; Guo, Shaozhe; Li, Gang; Wang, Xiaoqin; Kaplan, David L

2017-06-27

The structure of DNA is susceptible to alterations at high temperature and on changing pH, irradiation and exposure to DNase. Options to protect and preserve DNA during storage are important for applications in genetic diagnosis, identity authentication, drug development and bioresearch. In the present study, the stability of total DNA purified from human dermal fibroblast cells, as well as that of plasmid DNA, was studied in silk protein materials. The DNA/silk mixtures were stabilized on filter paper (silk/DNA + filter) or filter paper pre-coated with silk and treated with methanol (silk/DNA + PT-filter) as a route to practical utility. After air-drying and water extraction, 50-70% of the DNA and silk could be retrieved and showed a single band on electrophoretic gels. 6% silk/DNA + PT-filter samples provided improved stability in comparison with 3% silk/DNA + filter samples and DNA + filter samples for DNA preservation, with ∼40% of the band intensity remaining at 37 °C after 40 days and ∼10% after exposure to UV light for 10 hours. Quantitative analysis using the PicoGreen assay confirmed the results. The use of Tris/borate/EDTA (TBE) buffer enhanced the preservation and/or extraction of the DNA. The DNA extracted after storage maintained integrity and function based on serving as a functional template for PCR amplification of the gene for zinc finger protein 750 (ZNF750) and for transgene expression of red fluorescence protein (dsRed) in HEK293 cells. The high molecular weight and high content of a crystalline beta-sheet structure formed on the coated surfaces likely accounted for the preservation effects observed for the silk/DNA + PT-filter samples. Although similar preservation effects were also obtained for lyophilized silk/DNA samples, the rapid and simple processing available with the silk-DNA-filter membrane system makes it appealing for future applications.

Antioxidant and inflammatory cytokine in tears of patients with dry eye syndrome treated with preservative-free versus preserved eye drops.

PubMed

Jee, Donghyun; Park, Sang Hee; Kim, Man Soo; Kim, Eun Chul

2014-07-03

To compare the antioxidant and inflammatory cytokine activities in tears of patients with dry eye syndrome treated with preservative-free versus preserved eye drops. A total of 100 patients with moderate to severe dry eye syndrome were randomly divided into two groups. Fifty patients (group 1) were treated four times with preservative-free 0.1% sodium hyaluronate and 0.1% fluorometholone eye drops in the first month and with preservative-free 0.1% sodium hyaluronate and 0.05% cyclosporine eye drops in the second and third months. Another 50 patients (group 2) were treated with preserved eye drops on the same schedule. Ocular Surface Disease Index, corneal fluorescein staining, Schirmer I test, tear film breakup time, impression cytology, and antioxidant and inflammatory cytokine activities in tears were evaluated. Treatment with preservative-free eye drops led to significant improvements in symptoms, tear film breakup time, Schirmer I score, and impression cytologic findings compared to treatment with preserved eye drops (P < 0.05) in patients with dry eye syndrome. There was a statistically significant decrease in the IL-1β, IL-6, IL-12, and TNF-α concentrations and a statistically significant increase in the catalase, peroxiredoxin 2, superoxide dismutase 2 (SOD 2), and thioredoxin mean fluorescence intensity (MFI) of tears in the preservative-free group at 1, 2, and 3 months compared to initial values, respectively (P < 0.05). Treatment with preservative-free eye drops is effective against the dry eye syndrome. Preservative-free eye drops seem to be more effective than preserved eye drops in decreasing ocular inflammation and in increasing antioxidant contents in tears of patients with dry eye syndrome. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.

Develop guidelines for pavement preservation treatments and for building a pavement preservation program platform for Alaska.

DOT National Transportation Integrated Search

2012-11-01

This reports summarizes the project findings including the following: : An evaluation of the current pavement preservation program used in Alaska and a roadmap to grow the program : A summary of the best practices in terms of pavement preserv...

Preservation of volumetric bone density and geometry in trans women during cross-sex hormonal therapy: a prospective observational study.

PubMed

Van Caenegem, E; Wierckx, K; Taes, Y; Schreiner, T; Vandewalle, S; Toye, K; Kaufman, J-M; T'Sjoen, G

2015-01-01

Although trans women before the start of hormonal therapy have a less bone and muscle mass compared with control men, their bone mass and geometry are preserved during the first 2 years of hormonal therapy, despite of substantial muscle loss, illustrating the major role of estrogen in the male skeleton. The aim of this study is to examine the evolution of areal and volumetric bone density, geometry, and turnover in trans women undergoing sex steroid changes, during the first 2 years of hormonal therapy. In a prospective observational study, we examined 49 trans women (male-to-female) before and after 1 and 2 years of cross-sex hormonal therapy (CSH) in comparison with 49 age-matched control men measuring grip strength (hand dynamometer), areal bone mineral density (aBMD), and total body fat and lean mass using dual X-ray absorptiometry (DXA), bone geometry and volumetric bone mineral density, regional fat, and muscle area at the forearm and calf using peripheral quantitative computed tomography. Standardized treatment regimens were used with oral estradiol valerate, 4 mg daily (or transdermal 17-β estradiol 100 μg/24 h for patients >45 years old), both combined with oral cyproterone acetate 50 mg daily. Prior to CSH, trans women had lower aBMD at all measured sites (all p < 0.001), smaller cortical bone size (all p < 0.05), and lower muscle mass and strength and lean body mass (all p < 0.05) compared with control men. During CSH, muscle mass and strength decreased and all measures of fat mass increased (all p < 0.001). The aBMD increased at the femoral neck, radius, lumbar spine, and total body; cortical and trabecular bone remained stable and bone turnover markers decreased (all p < 0.05). Although trans women, before CSH, have a lower aBMD and cortical bone size compared with control men, their skeletal status is well preserved during CSH treatment, despite of substantial muscle loss.

Magnetic resonance imaging of the calcaneus: preliminary assessment of trabecular bone-dependent regional variations in marrow relaxation time compared with dual X-ray absorptiometry

NASA Technical Reports Server (NTRS)

Guglielmi, G.; Selby, K.; Blunt, B. A.; Jergas, M.; Newitt, D. C.; Genant, H. K.; Majumdar, S.

1996-01-01

RATIONALE AND OBJECTIVES: Marrow transverse relaxation time (T2*) in magnetic resonance (MR) imaging may be related to the density and structure of the surrounding trabecular network. We investigated regional variations of T2* in the human calcaneus and compared the findings with bone mineral density (BMD), as measured by dual X-ray absorpiometry (DXA). Short- and long-term precisions were evaluated first to determine whether MR imaging would be useful for the clinical assessment of disease status and progression in osteoporosis. METHODS: Gradient-recalled echo MR images of the calcaneus were acquired at 1.5 T from six volunteers. Measurements of T2* were compared with BMD and (for one volunteer) conventional radiography. RESULTS: T2* values showed significant regional variation; they typically were shortest in the superior region of the calcaneus. There was a linear correlation between MR and DXA measurements (r = .66 for 1/T2* versus BMD). Differences in T2* attributable to variations in analysis region-of-interest placement were not significant for five of the six volunteers. Sagittal MR images had short- and long-term precision errors of 4.2% and 3.3%, respectively. For DXA, the precision was 1.3% (coefficient of variation). CONCLUSION: MR imaging may be useful for trabecular bone assessment in the calcaneus. However, given the large regional variations in bone density and structure, the choice of an ROI is likely to play a major role in the accuracy, precision, and overall clinical efficacy of T2* measurements.

43 CFR 3.17 - Preservation of collection.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 43 Public Lands: Interior 1 2010-10-01 2010-10-01 false Preservation of collection. 3.17 Section 3.17 Public Lands: Interior Office of the Secretary of the Interior PRESERVATION OF AMERICAN ANTIQUITIES § 3.17 Preservation of collection. Every collection made under the authority of the act and of...

31 CFR 904.3 - Preservation of evidence.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Preservation of evidence. 904.3 Section 904.3 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) FEDERAL... DEPARTMENT OF JUSTICE § 904.3 Preservation of evidence. Referring agencies must take care to preserve all...

21 CFR 178.3800 - Preservatives for wood.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Preservatives for wood. 178.3800 Section 178.3800... Certain Adjuvants and Production Aids § 178.3800 Preservatives for wood. Preservatives may be safely used... to accomplish the technical effect of protecting the wood from decay, mildew, and water absorption...

21 CFR 178.3800 - Preservatives for wood.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Preservatives for wood. 178.3800 Section 178.3800... Certain Adjuvants and Production Aids § 178.3800 Preservatives for wood. Preservatives may be safely used... to accomplish the technical effect of protecting the wood from decay, mildew, and water absorption...

ACHP | Advisory Council on Historic Preservation News

Science.gov Websites

Search Youth & Historic Preservation Recovery Act skip specific nav links Home arrow Youth and ) wants the historic preservation community to expand! Educating young people on the benefits preservation published an article by ACHP Chairman Wayne Donaldson on the importance of getting young people involved in

The Preservation of Paper Collections in Archives.

ERIC Educational Resources Information Center

Adams, Cynthia Ann

The preservation methods used for paper collections in archives were studied through a survey of archives in the metropolitan Atlanta (Georgia) area. The preservation policy or program was studied, and the implications for conservators and preservation officers were noted. Twelve of 15 archives responded (response rate of 80 percent). Basic…

21 CFR 178.3800 - Preservatives for wood.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Preservatives for wood. 178.3800 Section 178.3800... Certain Adjuvants and Production Aids § 178.3800 Preservatives for wood. Preservatives may be safely used... to accomplish the technical effect of protecting the wood from decay, mildew, and water absorption...

21 CFR 178.3800 - Preservatives for wood.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Preservatives for wood. 178.3800 Section 178.3800... Certain Adjuvants and Production Aids § 178.3800 Preservatives for wood. Preservatives may be safely used... to accomplish the technical effect of protecting the wood from decay, mildew, and water absorption...