In vitro effectiveness of antimicrobial photodynamic therapy (APDT) using a 660 nm laser and malachite green dye in Staphylococcus aureus biofilms arranged on compact and cancellous bone specimens.

PubMed

Rosa, Luciano Pereira; da Silva, Francine Cristina; Nader, Sumaia Alves; Meira, Giselle Andrade; Viana, Magda Souza

2014-11-01

The aim of this study was to evaluate the in vitro effectiveness of antimicrobial photodynamic therapy (APDT) using a 660 nm visible laser combined with malachite green (MG) dye in the inactivation of Staphylococcus aureus (ATCC 25923) biofilms formed within compact and cancellous bone specimens. Specimens of 80 compact bones and 80 cancellous bones were contaminated with a standard suspension of S. aureus and incubated for 14 days at 37 °C to allow for the formation of biofilms. The specimens were divided into the following groups (n = 10) according to the treatment conditions: PS-L - (control - no treatment), PS+L - (only MG for 5 min), PS-L + 90 (only laser irradiation for 90 s), PS-L + 180 (only laser irradiation for 180 s), PS-L + 300 (only laser irradiation for 300 s), APDT90 (APDT for 90 s), APDT180 (APDT for 180 s), and APDT300 (APDT for 300 s). The findings were statistically analyzed using an ANOVA 5%. All of the experimental groups were significantly different from the control group for both the compact and cancellous bone specimens. The compact bone specimens that received APDT treatment (for either 90, 180, or 300 s) showed reductions in the log10 CFU/ml of S. aureus by a magnitude of 4 log10. Cancellous bone specimens treated with 300 s of APDT showed the highest efficacy, and these specimens had a reduction in S. aureus CFU/ml by a factor of 3 log10. APDT treatment using these proposed parameters in combination with MG was effective at inactivating S. aureus biofilms in compact and cancellous bone specimens.

Effectiveness of antimicrobial photodynamic therapy using a 660 nm laser and methyline blue dye for inactivating Staphylococcus aureus biofilms in compact and cancellous bones: An in vitro study.

PubMed

Rosa, Luciano Pereira; Silva, Francine Cristina da; Nader, Sumaia Alves; Meira, Giselle Andrade; Viana, Magda Souza

2015-06-01

New therapeutic modalities such as antimicrobial photodynamic therapy (APDT) has been investigated in order to be a valid alternative to the treatment of infections caused by different microorganisms. This work evaluated the in vitro effectiveness of Antimicrobial Photodynamic Therapy (APDT) using 660 nm laser combined with methylene blue dye to inactivate Staphylococcus aureus (ATCC 25923) biofilms in compact and cancellous bones specimens. Eighty specimens of compact bone and 80 specimens of cancellous bone were contaminated with a standard suspension of S. aureus and incubated for 14 days at 37°C to induce the formation of biofilms. The specimens were then divided into groups (n = 10) according to the established treatment: PS-L- (control--no treatment), PS+L- (only AM for 5 min in the dark), PS-L+90 (only laser irradiation for 90 s), PS-L+180 (only laser irradiation for 180 s), PS-L+300 (only laser irradiation for 300 s), APDT90 (APDT for 90 s), APDT180 (APDT for 180 s), and APDT300 (APDT for 300 s). The findings were statistically analyzed by ANOVA 5%. All of the experimental treatments showed a significant reduction (log 10 CFU/mL) of S. aureus biofilms in compact and cancellous bones specimens compared with the control group, and the APDT group was the most effective. Compact specimens treated with APDT showed the greatest reduction in biofilms compared with cancellous specimens, regardless of length of treatment. APDT with methylene blue dye and a 660 nm laser proved to be effective in inactivating S. aureus biofilms formed in compact and cancellous bone. Copyright © 2015 Elsevier B.V. All rights reserved.

Does metaphyseal cement augmentation in fracture management influence the adjacent subchondral bone and joint cartilage?: an in vivo study in sheep stifle joints.

PubMed

Goetzen, Michael; Hofmann-Fliri, Ladina; Arens, Daniel; Zeiter, Stephan; Stadelmann, Vincent; Nehrbass, Dirk; Richards, R Geoff; Blauth, Michael

2015-01-01

Augmentation of implants with polymethylmethacrylate (PMMA) bone cement in osteoporotic fractures is a promising approach to increase implant purchase. Side effects of PMMA for the metaphyseal bone, particularly for the adjacent subchondral bone plate and joint cartilage, have not yet been studied. The following experimental study investigates whether subchondral PMMA injection compromises the homeostasis of the subchondral bone and/or the joint cartilage.Ten mature sheep were used to simulate subchondral PMMA injection. Follow-ups of 2 (4 animals) and 4 (6 animals) months were chosen to investigate possible cartilage damage and subchondral plate alterations in the knee. Evaluation was completed by means of high-resolution peripheral quantitative computed tomography (HRpQCT) imaging, histopathological osteoarthritis scoring, and determination of glycosaminoglycan content in the joint cartilage. Results were compared with the untreated contralateral knee and statistically analyzed using nonparametric tests.Evaluation of the histological osteoarthritis score revealed no obvious cartilage damage for the treated knee; median histological score after 2 months 0 (range 4), after 4 months 1 (range 5). There was no significant difference when compared with the untreated control site after 2 and 4 months (P = 0.23 and 0.76, respectively). HRpQCT imaging showed no damage to the metaphyseal trabeculae. Glycosaminoglycan measurements of the treated joint cartilage after 4 months revealed no significant difference compared with the untreated cartilage (P = 0.24).The findings of this study support initial clinical observation that PMMA implant augmentation of metaphyseal fractures appears to be a safe procedure for fixation without harming the subchondral bone plate and adjacent joint cartilage.

Thermal contribution of compact bone to intervening tissue-like media exposed to planar ultrasound

NASA Astrophysics Data System (ADS)

Moros, Eduardo G.; Novak, Petr; Straube, William L.; Kolluri, Prashant; Yablonskiy, Dmitriy A.; Myerson, Robert J.

2004-03-01

than fourfold) were induced in soft tissue-like phantom materials adjacent (within ~5 mm) to a bovine bone as compared to similar experiments without bone inclusions. For low-power long-exposure experiments, where thermal conduction effects are significant, the thermal impact of bone reached at distances >10 mm from the bone surface (upstream of the bone). Therefore, we hypothesize that underlying bone exposed to planar ultrasound hyperthermia creates a high-temperature thermal boundary at depth that compensates for beam attenuation, thus producing more uniform temperature distribution in the intervening tissue layers. With appropriate technology, this finding may lead to improved thermal doses in superficial treatment sites such as the chest wall and the head/neck.

Effects of holmium:YAG laser on equine articular cartilage and subchondral bone adjacent to traumatic lesions

NASA Astrophysics Data System (ADS)

Collier, Michael A.; Haugland, L. Mark; Bellamy, Janine; Johnson, Lanny L.; Rohrer, Michael D.; Walls, Robert C.; Bartels, Kenneth E.

1994-09-01

The effects of Ho:YAG laser energy on articular cartilage and subchondral bone adjacent to traumatically created cartilage lesions in a continuous weight-bearing model were investigated. The 2.1 micrometers wavelength was delivered in hand-controlled contact and near-contact hard tissue arthroscopic surgery in a saline medium. Bilateral arthroscopy was performed on normal antebrachiocarpal and intercarpal joints of four adult horses. One-hundred twenty traumatic lesions were created on three weight-bearing articular surfaces with a knife, curette, or a motorized burr. Depths of the lesions were partial and full thickness. Configurations of the lesions were lacerations, scrapes, and craters. Left limbs were used as controls. Right limb lesions were treated with various intensities of laser energy. Animals were sacrificed at intervals of 1, 3, and 8 weeks. Gross microscopic anatomy was documented, and tissue sections were subjected to blind review by a pathologist. Mankin grading for cellularity and proteoglycan content was used to qualitatively evaluate cartilage response. Cartilage adjacent to all lesions exposed to laser energy had better cellularity and proteoglycan content than corresponding controls by Mankin grading.

Growth differentiation factor‑5 induces tenomodulin expression via phosphorylation of p38 and promotes viability of murine mesenchymal stem cells from compact bone.

PubMed

Qu, Yanlong; Zhou, Li; Lv, Bing; Wang, Chunlei; Li, Pengwei

2018-03-01

Growth differentiation factor (GDF)‑5 serves a role in tissue development and tenomodulin serves an important role in the development of tendons. The effects of GDF‑5 on mesenchymal stem cells (MSCs), particularly with regards to tendon bioengineering, are poorly understood. The present study aimed to investigate the effects of GDF‑5 on cell viability and tenomodulin expression in MSCs from murine compact bone. MSCs were isolated from murine compact bones and confirmed by flow cytometric analysis. In addition, the adipogenic, osteoblastic and chondrocyte differentiation capabilities of the MSCs were determined. MSCs were treated with GDF‑5 and the effects of GDF‑5 on MSC viability were determined. The mRNA and protein expression levels of tenomodulin were detected by reverse transcription‑quantitative polymerase chain reaction and western blotting, respectively. MSCs from murine compact bone were successfully isolated. GDF‑5 had optimal effects on cell viability at 100 ng/ml (+36.9% of control group without GDF‑5 treatment, P<0.01) and its effects peaked after 6 days of treatment (+56.6% of control group, P<0.001). Compared with the control group, treatment with 100 ng/ml GDF‑5 for 4 days enhanced the mRNA expression levels of tenomodulin (3.56±0.94 vs. 1.02±0.25; P<0.05). In addition, p38 was activated by GDF‑5, as determined by enhanced expression levels of phosphorylated p38 (p‑p38). The GDF‑5‑induced protein expression levels of p‑p38 and tenomodulin were markedly inhibited following treatment with SB203580, an inhibitor of p38 mitogen‑activated protein kinase. These results suggested that GDF‑5 treatment may increase tenomodulin protein expression via phosphorylation of p38 in MSCs from murine compact bone. These findings may aid the future development of tendon bioengineering.

Maxillary Interdental Osteotomies Have Low Morbidity for Alveolar Crestal Bone and Adjacent Teeth: A Cone Beam Computed Tomography-Based Study.

PubMed

Rodrigues, Daniel B; Campos, Paulo S F; Wolford, Larry M; Ignácio, Jaqueline; Gonçalves, João R

2018-02-19

Maxillary segmentation involving interdental osteotomies can have an adverse effect on the interdental crestal bone and adjacent teeth. The purpose of the present study was to evaluate the effect of interdental osteotomies on surrounding osseous and dental structures, including adjacent teeth, using cone beam computed tomography (CBCT), in patients who underwent segmental maxillary osteotomies. The present retrospective cohort study evaluated interdental osteotomy (IDO) sites between the lateral incisors and canines in patients treated with 3-piece Le Fort I osteotomies. CBCT scans were assessed using Kodac Dental Imaging software at specific intervals: T0 (before surgery), T1 (immediately after surgery), and T2 (a minimum of 11 months after surgery). The statistical analysis using a linear regression model was adjusted to compare the variables at the different intervals. Injury to the dental structures was assessed by radiological evidence of dental damage, the requirement for endodontic treatment, or tooth loss. We evaluated 94 IDO sites in 47 patients in the present study. The mean inter-radicular distance at T0 was 2.5 mm. A statistically significant increase was seen in the inter-radicular distance (between T1 and T0) of 0.72 mm, with a reduction of the alveolar bone crest height (between T2 and T0) of 0.19 mm (P < .001) for the group that underwent IDO. A weak correlation was found for this increase in the inter-radicular distance, with changes in the alveolar crest bone height. The potential complications associated with interdental osteotomies such as iatrogenic damage to the tooth structure, the need for endodontic treatment, and tooth loss were not encountered in any patients. We found very low morbidity for the interdental alveolar crest and the integrity of teeth adjacent to interdental osteotomies for patients who underwent maxillary segmentation between the lateral incisors and canines. Copyright © 2018 American Association of Oral and

Elastic-plastic fracture mechanics of compact bone

NASA Astrophysics Data System (ADS)

Yan, Jiahau

Bone is a composite composed mainly of organics, minerals and water. Most studies on the fracture toughness of bone have been conducted at room temperature. Considering that the body temperature of animals is higher than room temperature, and that bone has a high volumetric percentage of organics (generally, 35--50%), the effect of temperature on fracture toughness of bone should be studied. Single-edged V-shaped notched (SEVN) specimens were prepared to measure the fracture toughness of bovine femur and manatee rib in water at 0, 10, 23, 37 and 50°C. The fracture toughness of bovine femur and manatee rib were found to decrease from 7.0 to 4.3 MPa·m1/2 and from 5.5 to 4.1 MPa·m1/2, respectively, over a temperature range of 50°C. The decreases were attributed to inability of the organics to sustain greater stresses at higher temperatures. We studied the effects of water and organics on fracture toughness of bone using water-free and organics-free SEVN specimens at 23°C. Water-free and organics-free specimens were obtained by placing fresh bone specimen in a furnace at different temperatures. Water and organics significantly affected the fracture toughness of bone. Fracture toughness of the water-free specimens was 44.7% (bovine femur) and 32.4% (manatee rib) less than that of fresh-bone specimens. Fracture toughness of the organics-free specimens was 92.7% (bovine femur) and 91.5% (manatee rib) less than that of fresh bone specimens. Linear Elastic Fracture Mechanics (LEFM) is widely used to study bone. However, bone often has small to moderate scale yielding during testing. We used J integral, an elastic-plastic fracture-mechanics parameter, to study the fracture process of bone. The J integral of bovine femur increased from 6.3 KJ/mm2 at 23°C to 6.7 KJ/mm2 at 37°C. Although the fracture toughness of bovine bone decreases as the temperature increases, the J integral results show a contrary trend. The energy spent in advancing the crack beyond the linear

Long-term effects of vertebroplasty: adjacent vertebral fractures.

PubMed

Baroud, Gamal; Vant, Christianne; Wilcox, Ruth

2006-01-01

In today's aging population, osteoporosis-related fractures are an ever-growing concern. Vertebroplasty, a promising yet cost-effective treatment for vertebral compression fractures, has an increasing role. The first vertebroplasty procedures were reported by Deramond and Galibert in France in 1987, and international interest grew with continued development of clinical techniques and augmentation materials in Europe and the United States. Initial publications and presentations at peer review meetings demonstrated 60-90% success rates in providing immediate and significant pain relief. The objective of this review is to assemble experimental and computational biomechanical research whose goal is determining and preventing the negative long-term effects ofvertebroplasty, with a specific focus on adjacent vertebral fractures. Biomechanical studies using isolated cancellous bone cylinders have shown that osteoporotic cancellous bone samples augmented by the rigid bone cement were at least 12 times stiffer and 35 times stronger than the untreated osteoporotic cancellous bone samples. The biomechanical efficacy of the procedure to repair the fractured vertebrae and prevent further collapse is determined using single-vertebra models. The strength or load-bearing capacity of a single vertebra is significantly increased following augmentation when compared to the intact strength. However, there is no dear result regarding the overall stiffness of the single vertebra, with studies reporting contradictorily that the stiffness increases, decreases, or does not significantly alter following augmentation. The effects of vertebroplasty on adjacent structures are studied via multisegment models, whose results plainly oppose the findings of the single-vertebra and intravertebral models. Here, augmentation was shown to decrease the overall segment strength by 19% when compared to the matched controls. As well, there is a significant increase in disc pressure compared to the pre

Effect of Augmentation Material Stiffness on Adjacent Vertebrae after Osteoporotic Vertebroplasty Using Finite Element Analysis with Different Loading Methods.

PubMed

Cho, Ah-Reum; Cho, Sang-Bong; Lee, Jae-Ho; Kim, Kyung-Hoon

2015-11-01

Vertebroplasty is an effective treatment for osteoporotic vertebral fractures, which are one of the most common fractures associated with osteoporosis. However, clinical observation has shown that the risk of adjacent vertebral body fractures may increase after vertebroplasty. The mechanism underlying adjacent vertebral body fracture after vertebroplasty is not clear; excessive stiffness resulting from polymethyl methacrylate has been suspected as an important mechanism. The aim of our study was to compare the effects of bone cement stiffness on adjacent vertebrae after osteoporotic vertebroplasty under load-controlled versus displacement-controlled conditions. An experimental computer study using a finite element analysis. Medical research institute, university hospital, Korean. A three-dimensional digital anatomic model of L1/2 bone structure was reconstructed from human computed tomographic images. The reconstructed three-dimensional geometry was processed for finite element analysis such as meshing elements and applying material properties. Two boundary conditions, load-controlled and displacement-controlled methods, were applied to each of 5 deformation modes: compression, flexion, extension, lateral bending, and torsion. The adjacent L1 vertebra, irrespective of augmentation, revealed nearly similar maximum von Mises stresses under the load-controlled condition. However, for the displacement-controlled condition, the maximum von Mises stresses in the cortical bone and inferior endplate of the adjacent L1 vertebra increased significantly after cement augmentation. This increase was more significant than that with stiffer bone cement under all modes, except the torsion mode. The finite element model was simplified, excluding muscular forces and incorporating a large volume of bone cement, to more clearly demonstrate effects of bone cement stiffness on adjacent vertebrae after vertebroplasty. Excessive stiffness of augmented bone cement increases the risk of

Compaction dynamics of crunchy granular material

NASA Astrophysics Data System (ADS)

Guillard, François; Golshan, Pouya; Shen, Luming; Valdès, Julio R.; Einav, Itai

2017-06-01

Compaction of brittle porous material leads to a wide variety of densification patterns. Static compaction bands occurs naturally in rocks or bones, and have important consequences in industry for the manufacturing of powder tablets or metallic foams for example. Recently, oscillatory compaction bands have been observed in brittle porous media like snow or cereals. We will discuss the great variety of densification patterns arising during the compaction of puffed rice, including erratic compaction at low velocity, one or several travelling compaction bands at medium velocity and homogeneous compaction at larger velocity. The conditions of existence of each pattern are studied thanks to a numerical spring lattice model undergoing breakage and is mapped to the phase diagram of the patterns based on dimensionless characteristic quantities. This also allows to rationalise the evolution of the compaction behaviour during a single test. Finally, the localisation of compaction bands is linked to the strain rate sensitivity of the material.

Deep erosions of the palmar aspect of the navicular bone diagnosed by standing magnetic resonance imaging.

PubMed

Sherlock, C; Mair, T; Blunden, T

2008-11-01

Erosion of the palmar (flexor) aspect of the navicular bone is difficult to diagnose with conventional imaging techniques. To review the clinical, magnetic resonance (MR) and pathological features of deep erosions of the palmar aspect of the navicular bone. Cases of deep erosions of the palmar aspect of the navicular bone, diagnosed by standing low field MR imaging, were selected. Clinical details, results of diagnostic procedures, MR features and pathological findings were reviewed. Deep erosions of the palmar aspect of the navicular bone were diagnosed in 16 mature horses, 6 of which were bilaterally lame. Sudden onset of lameness was recorded in 63%. Radiography prior to MR imaging showed equivocal changes in 7 horses. The MR features consisted of focal areas of intermediate or high signal intensity on T1-, T2*- and T2-weighted images and STIR images affecting the dorsal aspect of the deep digital flexor tendon, the fibrocartilage of the palmar aspect, subchondral compact bone and medulla of the navicular bone. On follow-up, 7/16 horses (44%) had been subjected to euthanasia and only one was being worked at its previous level. Erosions of the palmar aspect of the navicular bone were confirmed post mortem in 2 horses. Histologically, the lesions were characterised by localised degeneration of fibrocartilage with underlying focal osteonecrosis and fibroplasia. The adjacent deep digital flexor tendon showed fibril formation and fibrocartilaginous metaplasia. Deep erosions of the palmar aspect of the navicular bone are more easily diagnosed by standing low field MR imaging than by conventional radiography. The lesions involve degeneration of the palmar fibrocartilage with underlying osteonecrosis and fibroplasia affecting the subchondral compact bone and medulla, and carry a poor prognosis for return to performance. Diagnosis of shallow erosive lesions of the palmar fibrocartilage may allow therapeutic intervention earlier in the disease process, thereby preventing

Compact DD generator-based neutron activation analysis (NAA) system to determine fluorine in human bone in vivo: a feasibility study.

PubMed

Mostafaei, Farshad; Blake, Scott P; Liu, Yingzi; Sowers, Daniel A; Nie, Linda H

2015-10-01

The subject of whether fluorine (F) is detrimental to human health has been controversial for many years. Much of the discussion focuses on the known benefits and detriments to dental care and problems that F causes in bone structure at high doses. It is therefore advantageous to have the means to monitor F concentrations in the human body as a method to directly assess exposure. F accumulates in the skeleton making bone a useful biomarker to assess long term cumulative exposure to F. This study presents work in the development of a non-invasive method for the monitoring of F in human bone. The work was based on the technique of in vivo neutron activation analysis (IVNAA). A compact deuterium-deuterium (DD) generator was used to produce neutrons. A moderator/reflector/shielding assembly was designed and built for human hand irradiation. The gamma rays emitted through the (19)F(n,γ)(20)F reaction were measured using a HPGe detector. This study was undertaken to (i) find the feasibility of using DD system to determine F in human bone, (ii) estimate the F minimum detection limit (MDL), and (iii) optimize the system using the Monte Carlo N-Particle eXtended (MCNPX) code in order to improve the MDL of the system. The F MDL was found to be 0.54 g experimentally with a neutron flux of 7   ×   10(8) n s(-1) and an optimized irradiation, decay, and measurement time scheme. The numbers of F counts from the experiment were found to be close to the (MCNPX) simulation results with the same irradiation and detection parameters. The equivalent dose to the irradiated hand and the effective dose to the whole body were found to be 0.9 mSv and 0.33 μSv, respectively. Based on these results, it is feasible to develop a compact DD generator based IVNAA system to measure bone F in a population with moderate to high F exposure.

Enhanced osteoblast adhesion on nanostructured selenium compacts for anti-cancer orthopedic applications.

PubMed

Tran, Phong; Webster, Thomas J

2008-01-01

Metallic bone implants possess numerous problems limiting their long-term efficacy, such as poor prolonged osseointegration, stress shielding, and corrosion under in vivo environments. Such problems are compounded for bone cancer patients since numerous patients receive orthopedic implants after cancerous bone resection. Unfortunately, current orthopedic materials were not originally developed to simultaneously increase healthy bone growth (as in traditional orthopedic implant applications) while inhibiting cancerous bone growth. The long-term objective of the present research is to investigate the use of nano-rough selenium to prevent bone cancer from re-occurring while promoting healthy bone growth for this select group of cancer patients. Selenium is a well known anti-cancer chemical. However, what is not known is how healthy bone cells interact with selenium. To determine this, selenium, spherical or semispherical shots, were pressed into cylindrical compacts and these compacts were then etched using 1N NaOH to obtain various surface structures ranging from the micron, submicron to nano scales. Changes in surface chemistry were also analyzed. Through these etching techniques, results of this study showed that biologically inspired surface roughness values were created on selenium compacts to match that of natural bone roughness. Moreover, results showed that healthy bone cell adhesion increased with greater nanometer selenium roughness (more closely matching that of titanium). In this manner, this study suggests that nano-rough selenium should be further tested for orthopedic applications involving bone cancer treatment.

Enhanced osteoblast adhesion on nanostructured selenium compacts for anti-cancer orthopedic applications

PubMed Central

Tran, Phong; Webster, Thomas J

2008-01-01

Metallic bone implants possess numerous problems limiting their long-term efficacy, such as poor prolonged osseointegration, stress shielding, and corrosion under in vivo environments. Such problems are compounded for bone cancer patients since numerous patients receive orthopedic implants after cancerous bone resection. Unfortunately, current orthopedic materials were not originally developed to simultaneously increase healthy bone growth (as in traditional orthopedic implant applications) while inhibiting cancerous bone growth. The long-term objective of the present research is to investigate the use of nano-rough selenium to prevent bone cancer from re-occurring while promoting healthy bone growth for this select group of cancer patients. Selenium is a well known anti-cancer chemical. However, what is not known is how healthy bone cells interact with selenium. To determine this, selenium, spherical or semispherical shots, were pressed into cylindrical compacts and these compacts were then etched using 1N NaOH to obtain various surface structures ranging from the micron, submicron to nano scales. Changes in surface chemistry were also analyzed. Through these etching techniques, results of this study showed that biologically inspired surface roughness values were created on selenium compacts to match that of natural bone roughness. Moreover, results showed that healthy bone cell adhesion increased with greater nanometer selenium roughness (more closely matching that of titanium). In this manner, this study suggests that nano-rough selenium should be further tested for orthopedic applications involving bone cancer treatment. PMID:18990948

Carbon-centered radicals in γ-irradiated bone substituting biomaterials based on hydroxyapatite.

PubMed

Sadlo, Jaroslaw; Strzelczak, Grazyna; Lewandowska-Szumiel, Malgorzata; Sterniczuk, Marcin; Pajchel, Lukasz; Michalik, Jacek

2012-09-01

Gamma irradiated synthetic hydroxyapatite, bone substituting materials NanoBone(®) and HA Biocer were examined using EPR spectroscopy and compared with powdered human compact bone. In every case, radiation-induced carbon centered radicals were recorded, but their molecular structures and concentrations differed. In compact bone and synthetic hydroxyapatite the main signal assigned to the CO(2) (-) anion radical was stable, whereas the signal due to the CO(3) (3-) radical dominated in NanoBone(®) and HA Biocer just after irradiation. However, after a few days of storage of these samples, also a CO(2) (-) signal was recorded. The EPR study of irradiated compact bone and the synthetic graft materials suggest that their microscopic structures are different. In FT-IR spectra of NanoBone(®), HA Biocer and synthetic hydroxyapatite the HPO(4) (2-) and CO(3) (2-) in B-site groups are detected, whereas in compact bone signals due to collagen dominate.

Beneath the minerals, a layer of round lipid particles was identified to mediate collagen calcification in compact bone formation.

PubMed

Xu, Shaohua; Yu, Jianqing J

2006-12-01

Astronauts lose 1-2% of their bone minerals per month during space flights. A systematic search for a countermeasure relies on a good understanding of the mechanism of bone formation at the molecular level. How collagen fibers, the dominant matrix protein in bones, are mineralized remains mysterious. Atomic force microscopy was carried out, in combination with immunostaining and Western blotting, on bovine tibia to identify unrecognized building blocks involved in bone formation and for an elucidation of the process of collagen calcification in bone formation. Before demineralization, tiles of hydroxyapatite crystals were found stacked along bundles of collagen fibers. These tiles were homogeneous in size and shape with dimensions 0.69 x 0.77 x 0.2 micro m(3). Demineralization dissolved these tiles and revealed small spheres with an apparent diameter around 145 nm. These spheres appeared to be lipid particles since organic solvents dissolved them. The parallel collagen bundles had widths mostly <2 micro m. Composition analysis of compact bones indicated a high content of apolar lipids, including triglycerides and cholesterol esters. Apolar lipids are known to form lipid droplets or lipoproteins, and these spheres are unlikely to be matrix vesicles as reported for collagen calcification in epiphyseal cartilages. Results from this study suggest that the layer of round lipid particles on collagen fibers mediates the mineral deposition onto the fibers. The homogeneous size of these lipid particles and the presence of apolipoprotein in demineralized bone tissue suggest the possibility that these particles might be of lipoprotein origin. More studies are needed to verify the last claim and to exclude the possibility that they are secreted lipid droplets.

Interstitial ultrasound ablation of tumors within or adjacent to bone: Contributions of preferential heating at the bone surface

NASA Astrophysics Data System (ADS)

Scott, Serena J.; Prakash, Punit; Salgaonkar, Vasant; Jones, Peter D.; Cam, Richard N.; Han, Misung; Rieke, Viola; Burdette, E. Clif; Diederich, Chris J.

2013-02-01

Preferential heating of bone due to high ultrasound attenuation may enhance thermal ablation performed with cathetercooled interstitial ultrasound applicators in or near bone. At the same time, thermally and acoustically insulating cortical bone may protect sensitive structures nearby. 3D acoustic and biothermal transient finite element models were developed to simulate temperature and thermal dose distributions during catheter-cooled interstitial ultrasound ablation near bone. Experiments in ex vivo tissues and tissue-mimicking phantoms were performed to validate the models and to quantify the temperature profiles and ablated volumes for various distances between the interstitial applicator and the bone surface. 3D patient-specific models selected to bracket the range of clinical usage were developed to investigate what types of tumors could be treated, applicator configurations, insertion paths, safety margins, and other parameters. Experiments show that preferential heating at the bone surface decreases treatment times compared to when bone is absent and that all tissue between an applicator and bone can be ablated when they are up to 2 cm apart. Simulations indicate that a 5-7 mm safety margin of normal bone is needed to protect (thermal dose < 6 CEM43°C and T < 45°C) sensitive structures behind ablated bone. In 3D patient-specific simulations, tumors 1.0-3.8 cm (L) and 1.3-3.0 cm (D) near or within bone were ablated (thermal dose > 240 CEM43°C) within 10 min without damaging the nearby spinal cord, lungs, esophagus, trachea, or major vasculature. Preferential absorption of ultrasound by bone may provide improved localization, faster treatment times, and larger treatment zones in tumors in and near bone compared to other heating modalities.

Compact DD generator based in vivo neutron activation analysis (IVNAA) system to determine sodium concentrations in human bone.

PubMed

Coyne, Mychaela Dawn; Neumann, Colby R; Zhang, Xinxin; Byrne, Patrick; Liu, Yingzi; Weaver, Connie M; Nie, Linda Huiling

2018-04-16

This study presents the development of a non-invasive method for monitoring Na in human bone. Many diseases, such as hypertension and osteoporosis, are closely associated with sodium (Na) retention in the human body. Na retention is generally evaluated by calculating the difference between dietary intake and excretion. There is currently no method to directly quantify Na retained in the body. Bone is a storage for many elements, including Na, which renders bone Na an ideal biomarker to study Na metabolism and retention. Approach: A customized compact deuterium-deuterium (DD) neutron generator was used to produce neutrons for in vivo neutron activation analysis (IVNAA), with a moderator/ reflector/ shielding assembly optimized for human hand irradiation in order to maximize the thermal neutron flux inside the irradiation cave and to limit radiation exposure to the hand and the whole body. Main Results: The experimental results show that the system is able to detect sodium levels in the bone as low as 12 g Na/g dry bone with an effective dose to the body of about 27 μSv. The simulation results agree with the numbers estimated from the experiment. Significance: This is expected to be a feasible method for measuring the change of Na in bone. The low detection limit indicates this will be a useful system to study the association between Na retention and related diseases. © 2018 Institute of Physics and Engineering in Medicine.

Radiographic evaluation of marginal bone levels adjacent to parallel-screw cylinder machined-neck implants and rough-surfaced microthreaded implants using digitized panoramic radiographs.

PubMed

Nickenig, Hans-Joachim; Wichmann, Manfred; Schlegel, Karl Andreas; Nkenke, Emeka; Eitner, Stephan

2009-06-01

The purpose of this split-mouth study was to compare macro- and microstructure implant surfaces at the marginal bone level during a stress-free healing period and under functional loading. From January to February 2006, 133 implants (70 rough-surfaced microthreaded implants and 63 machined-neck implants) were inserted in the mandible of 34 patients with Kennedy Class I residual dentitions and followed until February 2008. The marginal bone level was radiographically determined, using digitized panoramic radiographs, at four time points: at implant placement (baseline level), after the healing period, after 6 months of functional loading, and at the end of follow-up. The median follow-up time was 1.9 (range: 1.9-2.1) years. The machined-neck group had a mean crestal bone loss of 0.5 mm (range: 0-2.3) after the healing period, 0.8 mm after 6 months (range: 0-2.4), and 1.1 mm (range: 0-3) at the end of follow-up. The rough-surfaced microthreaded implant group had a mean bone loss of 0.1 mm (range: -0.4-2) after the healing period, 0.4 mm (range: 0-2.1) after 6 months, and 0.5 mm (range: 0-2.1) at the end of follow-up. The two implant types showed significant differences in marginal bone levels (healing period: P=0.01; end of follow-up: P<0.01). Radiographic evaluation of marginal bone levels adjacent to machined-neck or rough-surfaced microthreaded implants showed that implants with the microthreaded design caused minimal changes in crestal bone levels during healing (stress-free) and under functional loading.

Removal of bone in CT angiography by multiscale matched mask bone elimination.

PubMed

Gratama van Andel, H A F; Venema, H W; Streekstra, G J; van Straten, M; Majoie, C B L M; den Heeten, G J; Grimbergen, C A

2007-10-01

For clear visualization of vessels in CT angiography (CTA) images of the head and neck using maximum intensity projection (MIP) or volume rendering (VR) bone has to be removed. In the past we presented a fully automatic method to mask the bone [matched mask bone elimination (MMBE)] for this purpose. A drawback is that vessels adjacent to bone may be partly masked as well. We propose a modification, multiscale MMBE, which reduces this problem by using images at two scales: a higher resolution than usual for image processing and a lower resolution to which the processed images are transformed for use in the diagnostic process. A higher in-plane resolution is obtained by the use of a sharper reconstruction kernel. The out-of-plane resolution is improved by deconvolution or by scanning with narrower collimation. The quality of the mask that is used to remove bone is improved by using images at both scales. After masking, the desired resolution for the normal clinical use of the images is obtained by blurring with Gaussian kernels of appropriate widths. Both methods (multiscale and original) were compared in a phantom study and with clinical CTA data sets. With the multiscale approach the width of the strip of soft tissue adjacent to the bone that is masked can be reduced from 1.0 to 0.2 mm without reducing the quality of the bone removal. The clinical examples show that vessels adjacent to bone are less affected and therefore better visible. Images processed with multiscale MMBE have a slightly higher noise level or slightly reduced resolution compared with images processed by the original method and the reconstruction and processing time is also somewhat increased. Nevertheless, multiscale MMBE offers a way to remove bone automatically from CT angiography images without affecting the integrity of the blood vessels. The overall image quality of MIP or VR images is substantially improved relative to images processed with the original MMBE method.

The study of in vivo quantification of aluminum (Al) in human bone with a compact DD generator-based neutron activation analysis (NAA) system.

PubMed

Byrne, Patrick; Mostafaei, Farshad; Liu, Yingzi; Blake, Scott P; Koltick, David; Nie, Linda H

2016-05-01

The feasibility and methodology of using a compact DD generator-based neutron activation analysis system to measure aluminum in hand bone has been investigated. Monte Carlo simulations were used to simulate the moderator, reflector, and shielding assembly and to estimate the radiation dose. A high purity germanium (HPGe) detector was used to detect the Al gamma ray signals. The minimum detectable limit (MDL) was found to be 11.13 μg g(-1) dry bone (ppm). An additional HPGe detector would improve the MDL by a factor of 1.4, to 7.9 ppm. The equivalent dose delivered to the irradiated hand was calculated by Monte Carlo to be 11.9 mSv. In vivo bone aluminum measurement with the DD generator was found to be feasible among general population with an acceptable dose to the subject.

Compact biomedical pulsed signal generator for bone tissue stimulation

DOEpatents

Kronberg, J.W.

1993-06-08

An apparatus for stimulating bone tissue for stimulating bone growth or treating osteoporosis by applying directly to the skin of the patient an alternating current electrical signal comprising wave forms known to simulate the piezoelectric constituents in bone. The apparatus may, by moving a switch, stimulate bone growth or treat osteoporosis, as desired. Based on low-power CMOS technology and enclosed in a moisture-resistant case shaped to fit comfortably, two astable multivibrators produce the desired waveforms. The amplitude, pulse width and pulse frequency, and the subpulse width and subpulse frequency of the waveforms are adjustable. The apparatus, preferably powered by a standard 9-volt battery, includes signal amplitude sensors and warning signals indicate an output is being produced and the battery needs to be replaced.

Compact biomedical pulsed signal generator for bone tissue stimulation

DOEpatents

Kronberg, James W.

1993-01-01

An apparatus for stimulating bone tissue for stimulating bone growth or treating osteoporosis by applying directly to the skin of the patient an alternating current electrical signal comprising wave forms known to simulate the piezoelectric constituents in bone. The apparatus may, by moving a switch, stimulate bone growth or treat osteoporosis, as desired. Based on low-power CMOS technology and enclosed in a moisture-resistant case shaped to fit comfortably, two astable multivibrators produce the desired waveforms. The amplitude, pulse width and pulse frequency, and the subpulse width and subpulse frequency of the waveforms are adjustable. The apparatus, preferably powered by a standard 9-volt battery, includes signal amplitude sensors and warning signals indicate an output is being produced and the battery needs to be replaced.

Adjacent segment disease after instrumented fusion for adult lumbar spondylolisthesis: Incidence and risk factors.

PubMed

Zhong, Zhao-Ming; Deviren, Vedat; Tay, Bobby; Burch, Shane; Berven, Sigurd H

2017-05-01

A potential long-term complication of lumbar fusion is the development of adjacent segment disease (ASD), which may necessitate second surgery and adversely affect outcomes. The objective of this is to determine the incidence of ASD following instrumented fusion in adult patients with lumbar spondylolisthesis and to identify the risk factors for this complication. We retrospectively assessed adult patients who had undergone decompression and instrumented fusion for lumbar spondylolisthesis between January 2006 and December 2012. The incidence of ASD was analyzed. Potential risk factors included the patient-related factors, surgery-related factors, and radiographic variables such as sagittal alignment, preexisting disc degeneration and spinal stenosis at the adjacent segment. A total of 154 patients (mean age, 58.4 years) were included. Mean duration of follow-up was 28.6 months. Eighteen patients (11.7%) underwent a reoperation for ASD; 15 patients had reoperation at cranial ASD and 3 at caudal ASD. The simultaneous decompression at adjacent segment (p=0.002) and preexisting spinal stenosis at cranial adjacent segment (p=0.01) were identified as risk factors for ASD. The occurrence of ASD was not affected by patient-related factors, the types, grades and levels of spondylolisthesis, surgical approach, fusion procedures, levels of fusion, number of levels fused, types of bone graft, use of bone morphogenetic proteins, sagittal alignment, preexisting adjacent disc degeneration and preexisting spinal stenosis at caudal adjacent segments. Our findings suggest the overall incidence of ASD is 11.7% in adult patients with lumbar spondylolisthesis after decompression and instrumented fusion at a mean follow-up of 28.6 months, the simultaneous decompression at the adjacent segment and preexisting spinal stenosis at cranial adjacent segment are risk factors for ASD. Copyright © 2017. Published by Elsevier B.V.

[Preliminary result of allogenic bone and autogeneic-iliac bone in comminuted fracture reparation in rabbits].

PubMed

Wang, Zhi-qiang; Li, Qi-jia; Wang, Qi

2002-11-01

To observe the difference of the fracture reparation using autogeneic-iliac bone and allogenic bone. Comminuted fracture of humerus in two sides were made in rabbits. Autogeneic-iliac bone was implanted in one side, while allogenic bone of equal capacity was implanted in the other side. General observation, X-ray, and HE histologic section were done when the rabbits were put to death in different stages. One week after implantation, the graft had been enclosed by connective tissue without infiltration of the inflammatory cells. At the 2nd week, the graft had been enclosed in osteoplastic granulation tissue, and the cartilage callus had formed. At the 3rd week, there had been broken sequestrum among the callus; the cartilage had actively formed the bone; and the medulla had been making. At the 4th week, the sequestrum had disappeared, and the mature callus had appeared; the osteoblasts had arranged in a line around the edge of the mature callus. At the 5th week, the callus was strong, compact and approached mature bones. At the 6th week, there had been the compact lamellar structures and the complete haversian's systems. There was no significant difference between callus of two sides by using image quantitative analysis in the 3rd, 4th week (P > 0.05). The allogenic bone has good histocompatibility and bone conduction effect, and can be used for bone transplantation substitute with autogenous-iliac bone.

Anatomy, histology and elemental profile of long bones and ribs of the Asian elephant (Elephas maximus).

PubMed

Nganvongpanit, Korakot; Siengdee, Puntita; Buddhachat, Kittisak; Brown, Janine L; Klinhom, Sarisa; Pitakarnnop, Tanita; Angkawanish, Taweepoke; Thitaram, Chatchote

2017-09-01

This study evaluated the morphology and elemental composition of Asian elephant (Elephas maximus) bones (humerus, radius, ulna, femur, tibia, fibula and rib). Computerized tomography was used to image the intraosseous structure, compact bones were processed using histological techniques, and elemental profiling of compact bone was conducted using X-ray fluorescence. There was no clear evidence of an open marrow cavity in any of the bones; rather, dense trabecular bone was found in the bone interior. Compact bone contained double osteons in the radius, tibia and fibula. The osteon structure was comparatively large and similar in all bones, although the lacuna area was greater (P < 0.05) in the femur and ulna. Another finding was that nutrient foramina were clearly present in the humerus, ulna, femur, tibia and rib. Twenty elements were identified in elephant compact bone. Of these, ten differed significantly across the seven bones: Ca, Ti, V, Mn, Fe, Zr, Ag, Cd, Sn and Sb. Of particular interest was the finding of a significantly larger proportion of Fe in the humerus, radius, fibula and ribs, all bones without an open medullary cavity, which is traditionally associated with bone marrow for blood cell production. In conclusion, elephant bones present special characteristics, some of which may be important to hematopoiesis and bone strength for supporting a heavy body weight.

Carbon nanotubes with high bone-tissue compatibility and bone-formation acceleration effects.

PubMed

Usui, Yuki; Aoki, Kaoru; Narita, Nobuyo; Murakami, Narumichi; Nakamura, Isao; Nakamura, Koichi; Ishigaki, Norio; Yamazaki, Hiroshi; Horiuchi, Hiroshi; Kato, Hiroyuki; Taruta, Seiichi; Kim, Yoong Ahm; Endo, Morinobu; Saito, Naoto

2008-02-01

Carbon nanotubes (CNTs) have been used in various fields as composites with other substances or alone to develop highly functional materials. CNTs hold great interest with respect to biomaterials, particularly those to be positioned in contact with bone such as prostheses for arthroplasty, plates or screws for fracture fixation, drug delivery systems, and scaffolding for bone regeneration. Accordingly, bone-tissue compatibility of CNTs and CNT influence on bone formation are important issues, but the effects of CNTs on bone have not been delineated. Here, it is found that multi-walled CNTs adjoining bone induce little local inflammatory reaction, show high bone-tissue compatibility, permit bone repair, become integrated into new bone, and accelerate bone formation stimulated by recombinant human bone morphogenetic protein-2 (rhBMP-2). This study provides an initial investigational basis for CNTs in biomaterials that are used adjacent to bone, including uses to promote bone regeneration. These findings should encourage development of clinical treatment modalities involving CNTs.

Longitudinal changes in tooth/single-implant relationship and bone topography: an 8-year retrospective analysis.

PubMed

Chang, Moontaek; Wennström, Jan L

2012-06-01

To evaluate longitudinal changes in tooth/implant relationship and bone topography at single implants with a microthreaded, conical marginal portion (Astra Tech ST® implants, Astra Tech AB, Mölndal, Sweden). Thirty-one subjects with single implant-supported restorations in the esthetic zone were included. Radiographs obtained at crown installation and 1, 5, and 8 years of follow-up were analyzed with regard to changes in (1) bone level at the implant and adjacent teeth and (2) vertical position of adjacent teeth relative to the single implant. The mean marginal bone loss amounted to 0.1 mm at both implants and adjacent teeth during the 8 years of follow-up. Regression analysis failed to identify significant explanatory factors for observed variance in bone level change at the adjacent tooth surfaces. Vertical change in position of the teeth relative to the implants was more frequent and significantly greater in incisor compared with premolar tooth region but not associated with gender or age. The marginal bone level at teeth adjacent to single implants with a microthreaded conical marginal part was not influenced by horizontal and vertical tooth-implant distances. Continuous eruption of adjacent teeth may result in infraocclusal positioning of a single-implant restoration. © 2010 Wiley Periodicals, Inc.

Vacuum-sintered body of a novel apatite for artificial bone

NASA Astrophysics Data System (ADS)

Tamura, Kenichi; Fujita, Tatsushi; Morisaki, Yuriko

2013-12-01

We produced regenerative artificial bone material and bone parts using vacuum-sintered bodies of a novel apatite called "Titanium medical apatite (TMA®)" for biomedical applications. TMA was formed by chemically connecting a Ti oxide molecule with the reactive [Ca10(PO4)6] group of Hydroxyapatite (HAp). The TMA powders were kneaded with distilled water, and solid cylinders of compacted TMA were made by compression molding at 10 MPa using a stainless-steel vessel. The TMA compacts were dried and then sintered in vacuum (about 10-3 Pa) or in air using a resistance heating furnace in the temperature range 1073-1773 K. TMA compacts were sintered at temperatures greater than 1073 K, thus resulting in recrystallization. The TMA compact bodies sintered in the range 1273-1773 K were converted into mixtures composed of three crystalline materials: α-TCP (tricalcium phosphate), β-TCP, and Perovskite-CaTiO3. The Perovskite crystals were stable and hard. In vacuum-sintering, the Perovskite crystals were transformed into fibers (approximately 1 µm in diameter × 8 µm in length), and the fiber distribution was uniform in various directions. We refer to the TMA vacuum-sintered bodies as a "reinforced composite material with Perovskite crystal fibers." However, in atmospheric sintering, the Perovskite crystals were of various sizes and were irregularly distributed as a result of the effect of oxygen. After sintering temperature at 1573 K, the following results were obtained: the obtained TMA vacuum-sintered bodies (1) were white, (2) had a density of approximately 2300 kg/m3 (corresponding to that of a compact bone or a tooth), and had a thermal conductivity of approximately 31.3 W/(m·K) (corresponding to those of metal or ceramic implants). Further, it was possible to cut the TMA bodies into various forms with a cutting machine. An implant made of TMA and inserted into a rabbit jaw bone was covered by new bone tissues after just one month because of the high

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.

Orbital stability of compact three-planets systems.

NASA Astrophysics Data System (ADS)

Gavino, Sacha; Lissauer, Jack

2018-04-01

Recent discoveries unveiled a significant number of compact multi-planetary systems, where the adjacent planets orbits are much closer to those found in the Solar System. Studying the orbital stability of such compact systems provides information on how they form and how long they survive. We performed a general study of three Earth-like planets orbiting a Sun-mass star in circular and coplanar prograde orbits. The simulations were performed over a wide range of mutual Hill radii and were conducted for virtual times reaching at most 10 billion years. Both equally-spaced and unequally spaced planet systems are investigated. We recover the results of previous studies done for systems of planets spaced uniformly in mutual Hill radius and we investigate mean motion resonances and test chaos. We also study systems with different initial spacing between the adjacent inner pair of planets and the outer pair of planets and we displayed their lifetime on a grid at different resolution. Over 45000 simulations have been done. We then characterize isochrones for lifetime of systems of equivalent spacing. We find that the stability time increases significantly for values of mutual Hill radii beyond 8. We also study the affects of mean motion resonances, the degree of symmetry in the grid and test chaos.

The development of a composite bone model for training on placement of dental implants

PubMed Central

Alkhodary, Mohamed Ahmed; Abdelraheim, Abdelraheim Emad Eldin; Elsantawy, Abd Elaleem Hassan; Al Dahman, Yousef Hamad; Al-Mershed, Mohammed

2015-01-01

Objectives It takes a lot of training on patients for both undergraduate to develop clinical sense as regards to the placement of dental implants in the jaw bones, also, the models provided by the dental implant companies for training are usually made of strengthened synthetic foams, which are far from the composition, and tactile sense provided by natural bone during drilling for clinical placement of dental implants. Methodology This is an in-vitro experimental study which utilized bovine femur bone, where the shaft of the femur provided the surface compact layer, and the head provided the cancellous bone layer, to provide a training model similar to jaw bones macroscopic anatomy. Both the compact and cancellous bone samples were characterized using mechanical compressive testing. Results The elastic moduli of the cancellous and cortical femur bone were comparable to those of the human mandible, and the prepared training model provided a more lifelike condition during the drilling and placement of dental implants. Conclusion The composite bone model developed simulated the macroscopic anatomy of the jaw bones having a surface layer of compact bone, and a core of cancellous bone, and provided a better and a more natural hands-on experience for placement of dental implants as compared to plastic models made of polyurethane. PMID:26309434

The development of a composite bone model for training on placement of dental implants.

PubMed

Alkhodary, Mohamed Ahmed; Abdelraheim, Abdelraheim Emad Eldin; Elsantawy, Abd Elaleem Hassan; Al Dahman, Yousef Hamad; Al-Mershed, Mohammed

2015-04-01

It takes a lot of training on patients for both undergraduate to develop clinical sense as regards to the placement of dental implants in the jaw bones, also, the models provided by the dental implant companies for training are usually made of strengthened synthetic foams, which are far from the composition, and tactile sense provided by natural bone during drilling for clinical placement of dental implants. This is an in-vitro experimental study which utilized bovine femur bone, where the shaft of the femur provided the surface compact layer, and the head provided the cancellous bone layer, to provide a training model similar to jaw bones macroscopic anatomy. Both the compact and cancellous bone samples were characterized using mechanical compressive testing. The elastic moduli of the cancellous and cortical femur bone were comparable to those of the human mandible, and the prepared training model provided a more lifelike condition during the drilling and placement of dental implants. The composite bone model developed simulated the macroscopic anatomy of the jaw bones having a surface layer of compact bone, and a core of cancellous bone, and provided a better and a more natural hands-on experience for placement of dental implants as compared to plastic models made of polyurethane.

Effects of compaction pressure and particle shape on the porosity and compression mechanical properties of sintered Ti6Al4V powder compacts for hard tissue implantation.

PubMed

Güden, Mustafa; Celik, Emrah; Hizal, Alpay; Altindiş, Mustafa; Cetiner, Sinan

2008-05-01

Sintered Ti6Al4V powder compacts potentially to be used in implant applications were prepared using commercially available spherical and angular powders (100-200 mum) within the porosity range of 34-54%. Cylindrical green powder compacts were cold compacted at various pressures and then sintered at 1200 degrees C for 2 h. The final percent porosity and mean pore sizes were determined as functions of the applied compaction pressure and powder type. The mechanical properties were investigated through compression testing. Results have shown that yield strength of the powder compacts of 40-42% porosity was comparable with that of human cortical bone. As compared with previously investigated Ti powder compacts, Ti6Al4V powder compacts showed higher strength at similar porosity range. Microscopic observations on the failed compact samples revealed that failure occurred primarily by the separation of interparticle bond regions in the planes 45 degrees to the loading axis. Copyright 2007 Wiley Periodicals, Inc.

Bone histology in extant and fossil penguins (Aves: Sphenisciformes).

PubMed

Ksepka, Daniel T; Werning, Sarah; Sclafani, Michelle; Boles, Zachary M

2015-11-01

Substantial changes in bone histology accompany the secondary adaptation to life in the water. This transition is well documented in several lineages of mammals and non-avian reptiles, but has received relatively little attention in birds. This study presents new observations on the long bone microstructure of penguins, based on histological sections from two extant taxa (Spheniscus and Aptenodytes) and eight fossil specimens belonging to stem lineages (†Palaeospheniscus and several indeterminate Eocene taxa). High bone density in penguins results from compaction of the internal cortical tissues, and thus penguin bones are best considered osteosclerotic rather than pachyostotic. Although the oldest specimens sampled in this study represent stages of penguin evolution that occurred at least 25 million years after the loss of flight, major differences in humeral structure were observed between these Eocene stem taxa and extant taxa. This indicates that the modification of flipper bone microstructure continued long after the initial loss of flight in penguins. It is proposed that two key transitions occurred during the shift from the typical hollow avian humerus to the dense osteosclerotic humerus in penguins. First, a reduction of the medullary cavity occurred due to a decrease in the amount of perimedullary osteoclastic activity. Second, a more solid cortex was achieved by compaction. In extant penguins and †Palaeospheniscus, most of the inner cortex is formed by rapid osteogenesis, resulting an initial latticework of woven-fibered bone. Subsequently, open spaces are filled by slower, centripetal deposition of parallel-fibered bone. Eocene stem penguins formed the initial latticework, but the subsequent round of compaction was less complete, and thus open spaces remained in the adult bone. In contrast to the humerus, hindlimb bones from Eocene stem penguins had smaller medullary cavities and thus higher compactness values compared with extant taxa. Although

Bone histology in extant and fossil penguins (Aves: Sphenisciformes)

PubMed Central

Ksepka, Daniel T; Werning, Sarah; Sclafani, Michelle; Boles, Zachary M

2015-01-01

Substantial changes in bone histology accompany the secondary adaptation to life in the water. This transition is well documented in several lineages of mammals and non-avian reptiles, but has received relatively little attention in birds. This study presents new observations on the long bone microstructure of penguins, based on histological sections from two extant taxa (Spheniscus and Aptenodytes) and eight fossil specimens belonging to stem lineages (†Palaeospheniscus and several indeterminate Eocene taxa). High bone density in penguins results from compaction of the internal cortical tissues, and thus penguin bones are best considered osteosclerotic rather than pachyostotic. Although the oldest specimens sampled in this study represent stages of penguin evolution that occurred at least 25 million years after the loss of flight, major differences in humeral structure were observed between these Eocene stem taxa and extant taxa. This indicates that the modification of flipper bone microstructure continued long after the initial loss of flight in penguins. It is proposed that two key transitions occurred during the shift from the typical hollow avian humerus to the dense osteosclerotic humerus in penguins. First, a reduction of the medullary cavity occurred due to a decrease in the amount of perimedullary osteoclastic activity. Second, a more solid cortex was achieved by compaction. In extant penguins and †Palaeospheniscus, most of the inner cortex is formed by rapid osteogenesis, resulting an initial latticework of woven-fibered bone. Subsequently, open spaces are filled by slower, centripetal deposition of parallel-fibered bone. Eocene stem penguins formed the initial latticework, but the subsequent round of compaction was less complete, and thus open spaces remained in the adult bone. In contrast to the humerus, hindlimb bones from Eocene stem penguins had smaller medullary cavities and thus higher compactness values compared with extant taxa. Although

PULSED FOCUSED ULTRASOUND TREATMENT OF MUSCLE MITIGATES PARALYSIS-INDUCED BONE LOSS IN THE ADJACENT BONE: A STUDY IN A MOUSE MODEL

PubMed Central

Poliachik, Sandra L.; Khokhlova, Tatiana D.; Wang, Yak-Nam; Simon, Julianna C.; Bailey, Michael R.

2015-01-01

Bone loss can result from bed rest, space flight, spinal cord injury or age-related hormonal changes. Current bone loss mitigation techniques include pharmaceutical interventions, exercise, pulsed ultrasound targeted to bone and whole body vibration. In this study, we attempted to mitigate paralysis-induced bone loss by applying focused ultrasound to the midbelly of a paralyzed muscle. We employed a mouse model of disuse that uses onabotulinumtoxinA-induced paralysis, which causes rapid bone loss in 5 d. A focused 2 MHz transducer applied pulsed exposures with pulse repetition frequency mimicking that of motor neuron firing during walking (80 Hz), standing (20 Hz), or the standard pulsed ultrasound frequency used in fracture healing (1 kHz). Exposures were applied daily to calf muscle for 4 consecutive d. Trabecular bone changes were characterized using micro-computed tomography. Our results indicated that application of certain focused pulsed ultrasound parameters was able to mitigate some of the paralysis-induced bone loss. PMID:24857416

Does bone cement in percutaneous vertebroplasty act as a stress riser?

PubMed

Aquarius, René; van der Zijden, Astrid Maria; Homminga, Jasper; Verdonschot, Nico; Tanck, Esther

2013-11-15

An in vitro cadaveric study. To determine whether percutaneous vertebroplasty (PVP) with a clinically relevant amount of bone cement is capable of causing stress peaks in adjacent-level vertebrae. It is often suggested that PVP of a primary spinal fracture causes stress peaks in adjacent vertebrae, thereby leading to additional fractures. The in vitro studies that demonstrated this relationship, however, use bigger volumes of bone cement used clinically. Ten fresh-frozen vertebrae were loaded until failure, while registering force and displacement as well as the pressure under the lower endplate. After failure, the vertebrae were augmented with clinically relevant amounts of bone cement and then again loaded until failure. The force, displacement, and pressure under the lower endplate were again registered. Stress peaks were not related to the location of the injected bone cement. Both failure load and stiffness were significantly lower after augmentation. On the basis of our findings, we conclude that vertebral augmentation with clinically relevant amounts of bone cement does not lead to stress peaks under the endplate. It is therefore unlikely that PVP, in itself, causes detrimental stresses in the adjacent vertebrae, leading to new vertebral fractures. N/A.

Compaction of forest soil by logging machinery favours occurrence of prokaryotes.

PubMed

Schnurr-Pütz, Silvia; Bååth, Erland; Guggenberger, Georg; Drake, Harold L; Küsel, Kirsten

2006-12-01

Soil compaction caused by passage of logging machinery reduces the soil air capacity. Changed abiotic factors might induce a change in the soil microbial community and favour organisms capable of tolerating anoxic conditions. The goals of this study were to resolve differences between soil microbial communities obtained from wheel-tracks (i.e. compacted) and their adjacent undisturbed sites, and to evaluate differences in potential anaerobic microbial activities of these contrasting soils. Soil samples obtained from compacted soil had a greater bulk density and a higher pH than uncompacted soil. Analyses of phospholipid fatty acids demonstrated that the eukaryotic/prokaryotic ratio in compacted soils was lower than that of uncompacted soils, suggesting that fungi were not favoured by the in situ conditions produced by compaction. Indeed, most-probable-number (MPN) estimates of nitrous oxide-producing denitrifiers, acetate- and lactate-utilizing iron and sulfate reducers, and methanogens were higher in compacted than in uncompacted soils obtained from one site that had large differences in bulk density. Compacted soils from this site yielded higher iron-reducing, sulfate-reducing and methanogenic potentials than did uncompacted soils. MPN estimates of H2-utilizing acetogens in compacted and uncompacted soils were similar. These results indicate that compaction of forest soil alters the structure and function of the soil microbial community and favours occurrence of prokaryotes.

Adjacent vertebral body fracture following vertebroplasty with polymethylmethacrylate or calcium phosphate cement: biomechanical evaluation of the cadaveric spine.

PubMed

Nouda, Shinya; Tomita, Seiji; Kin, Akihiro; Kawahara, Kunihiko; Kinoshita, Mitsuo

2009-11-15

A biomechanical study using human cadaveric thoracolumbar spinal columns. To compare the effect of treatment by vertebroplasty (VP) with polymethylmethacrylate cement and VP with calcium phosphate cement on the creation of adjacent vertebral body fracture following VP. Adjacent vertebral body fractures have been reported as a complication following VP. Twenty-four spinal columns (T10-L2) from human cadavers were subjected to dual energy radiograph absorptiometry to assess bone mineral density. They were divided into the P group and C group, and experimental vertebral compression fractures were created at T12 vertebrae. T12 vertebrae were augmented with polymethylmethacrylate and calcium phosphate cement in the P group and C group, respectively. Each spinal column was compressed until a new fracture occurred at any vertebra, and the location of newly fractured vertebra and failure load was investigated. There was no significant difference in bone mineral density at each level within each group. In the P group, a new fracture occurred at T10 in 2 specimens, T11 in 8, and L1 in 2. In the C group, it occurred at T10 in 1 specimen, T11 in 2, L1 in 1, and T12 (treated vertebra) in 8. The failure loads of the spinal column were 1774.8+/-672.3 N and 1501.2+/-556.5 N in the P group and C group, respectively. There was no significant difference in the failure load of the spinal column between each group. New vertebral fractures occurred at the vertebra adjacent to augmented vertebrae in the P group and in the augmented vertebrae in the C group. The difference in the fractured site may be because of the difference in strength between the 2 bone filler materials. Therefore, the strength of bone filler materials is considered a risk factor in developing adjacent vertebral body fractures after VP.

Radiographic evaluation of bone adaptation adjacent to percutaneous osseointegrated prostheses in a sheep model.

PubMed

Jeyapalina, Sujee; Beck, James Peter; Bachus, Kent N; Chalayon, Ornusa; Bloebaum, Roy D

2014-10-01

Percutaneous osseointegrated prostheses (POPs) are being investigated as an alternative to conventional socket suspension and require a radiographic followup in translational studies to confirm that design objectives are being met. In this 12-month animal study, we determined (1) radiographic signs of osseointegration and (2) radiographic signs of periprosthetic bone hypertrophy and resorption (adaptation) and (3) confirmed them with the histologic evidence of host bone osseointegration and adaptation around a novel, distally porous-coated titanium POP with a collar. A POP device was designed to fit the right metacarpal bone of sheep. Amputation and implantation surgeries (n = 14) were performed, and plane-film radiographs were collected quarterly for 12 months. Radiographs were assessed for osseointegration (fixation) and bone adaptation (resorption and hypertrophy). The cortical wall and medullary canal widths were used to compute the cortical index and expressed as a percentage. Based on the cortical index changes and histologic evaluations, bone adaptation was quantified. Radiographic data showed signs of osseointegration including those with incomplete seating against the collar attachment. Cortical index data indicated distal cortical wall thinning if the collar was not seated distally. When implants were bound proximally, bone resorbed distally and the diaphyseal cortex hypertrophied. Histopathologic evidence and cortical index measurements confirmed the radiographic indications of adaptation and osseointegration. Distal bone loading, through collar attachment and porous coating, limited the distal bone resorption. Serial radiographic studies, in either animal models or preclinical trials for new POP devices, will help to determine which designs are likely to be safe over time and avoid implant failures.

Computational segmentation of collagen fibers in bone matrix indicates bone quality in ovariectomized rat spine.

PubMed

Daghma, Diaa Eldin S; Malhan, Deeksha; Simon, Paul; Stötzel, Sabine; Kern, Stefanie; Hassan, Fathi; Lips, Katrin Susanne; Heiss, Christian; El Khassawna, Thaqif

2018-05-01

Bone loss varies according to disease and age and these variations affect bone cells and extracellular matrix. Osteoporosis rat models are widely investigated to assess mechanical and structural properties of bone; however, bone matrix proteins and their discrepant regulation of diseased and aged bone are often overlooked. The current study considered the spine matrix properties of ovariectomized rats (OVX) against control rats (Sham) at 16 months of age. Diseased bone showed less compact structure with inhomogeneous distribution of type 1 collagen (Col1) and changes in osteocyte morphology. Intriguingly, demineralization patches were noticed in the vicinity of blood vessels in the OVX spine. The organic matrix structure was investigated using computational segmentation of collagen fibril properties. In contrast to the aged bone, diseased bone showed longer fibrils and smaller orientation angles. The study shows the potential of quantifying transmission electron microscopy images to predict the mechanical properties of bone tissue.

Cranial Bone Graft Donor Site Reconstruction.

PubMed

Çelik, Muzaffer

2017-01-01

My most important concern, in my entire experience with cranial bone grafting procedures, is managing the bone graft donor site such as donor site cavity from harvesting and weakness of the cranium. The most common patient complaint, following cranial bone grafting for aesthetic indications, is the presence of a cavity at the donor site. The authors have managed more than 200 patients since 2001, wherein the cranial bone graft-donor sites were reconstructed with tiny bone chip lamellae harvested from the area adjacent to the donor site. This procedure was associated with a low incidence of patient complaints, thereby suggesting higher patient satisfaction. This approach for cranial bone grafting appears to have a high patient acceptance.

Treatment of Osteomyelitis: A Case for Disruption of the Affected Adjacent Periosteum.

PubMed

Hudson, John W; Daly, Austin P; Foster, Michael

2017-10-01

To evaluate the response of mandibular osteomyelitis treated by surgical decortication with disruption of the affected adjacent periosteum in concert with long-term targeted antibiotic therapy. The hypothesis is that, by removing the buccal cortical plate and disrupting the hypertrophically inflamed adjacent periosteum, the medullary bone will be brought in contact with bleeding tissue and circulating immunologic factors and antibiotics, which will promote definitive resolution. A retrospective review was conducted of 7 patient charts with associated radiographs from November 2010 to August 2016 treated by the first author at the University of Tennessee Medical Center (Knoxville, TN). Patients with chronic suppurative or nonsuppurative osteomyelitis of the mandible without condylar involvement or pathologic fracture were selected and treated with decortication with periosteal disruption in combination with long-term targeted antibiotic therapy. Seven patients (3 women and 4 men; mean age, 60 yr) underwent decortication with periosteal disruption of the affected area and received at least 6 weeks of targeted intravenous antibiotics. Computed tomography was performed preoperatively and a repeat study was performed after completion of antibiotics. In each case, post-treatment imaging showed definitive resolution after treatment with decortication in concert with disruption of the inflamed hypertrophic periosteum and intravenous antibiotics. Debridement of the infected cortical bone with restoration of the blood supply through disruption of the adjacent periosteum provided definitive resolution of mandibular osteomyelitis in the 7 patients treated. The hypothesis is that disruption of the affected adjacent periosteum reintroduces an immune-mediated response in concert with improved antibiotic delivery to and penetrance of the diseased mandible, aiding in definitive resolution. Decortication with periosteal disruption allows for preservation of the inferior alveolar

Correlation between ultrasound velocity and densitometry in fresh and demineralized cortical bone.

PubMed

Mesquita, Alessandro Queiroz de; Barbieri, Giuliano; Barbieri, Claudio Henrique

2016-11-01

To compare ultrasound propagation velocity with densitometry in the diaphyseal compact cortical bone of whole sheep metatarsals. The transverse ultrasound velocity and bone mineral density of 5-cm-long diaphyseal bone segments were first measured. The bone segments were then divided into four groups of 15 segments each and demineralized in an aqueous 0.5 N hydrochloric acid solution for 6, 12, 24 or 36 hours. All measurements were repeated after demineralization for each time duration and the values measured before and after demineralization were compared. Ultrasound velocity and bone mineral density decreased with demineralization time, and most differences in the pre- and post-demineralization values within each group and between groups were significant: A moderate correlation coefficient (r=0.75956) together with a moderate agreement was determined between both post-demineralization parameters, detected by the Bland-Altman method. We conclude that both ultrasound velocity and bone mineral density decrease as a result of demineralization, thus indicating that bone mineral content is of great importance for maintaining the acoustic parameters of cortical bone, as observed for cancellous bone. Ultrasound velocity can be used to evaluate both compact cortical bone quality and bone mineral density.

Biomimetics of Bone Implants: The Regenerative Road.

PubMed

Brett, Elizabeth; Flacco, John; Blackshear, Charles; Longaker, Michael T; Wan, Derrick C

2017-01-01

The current strategies for healing bone defects are numerous and varied. At the core of each bone healing therapy is a biomimetic mechanism, which works to enhance bone growth. These range from porous scaffolds, bone mineral usage, collagen, and glycosaminoglycan substitutes to transplanted cell populations. Bone defects face a range of difficulty in their healing, given the composite of dense outer compact bone and blood-rich inner trabecular bone. As such, the tissue possesses a number of inherent characteristics, which may be clinically harnessed as promoters of bone healing. These include mechanical characteristics, mineral composition, native collagen content, and cellular fraction of bone. This review charts multiple biomimetic strategies to help heal bony defects in large and small osseous injury sites, with a special focus on cell transplantation.

Molecular and structural assessment of alveolar bone during tooth eruption and function in the miniature pig, Sus scrofa

PubMed Central

Yeh, Kuang-Dah; Popowics, Tracy

2011-01-01

Summary The development of alveolar bone adjacent to the tooth root during tooth eruption is not well understood. This study tested the hypothesis that predominantly woven bone forms adjacent to tooth roots during tooth eruption, but that this immature structure transitions to lamellar bone when the tooth comes into function. Additionally, bone resorption was predicted to play a key role in transitioning immature bone to more mature, load-bearing tissue. Miniature pigs were compared at two occlusal stages, 13 weeks (n=3), corresponding with the mucosal penetration stage of M1 tooth eruption, and 23 weeks (n=3), corresponding with early occlusion of M1/M1. Bone samples for RNA extraction and qRT-PCR analysis were harvested from the diastema and adjacent to M1 roots on one side. Following euthanasia, bone samples for hematoxylin and eosin and TRAP staining were harvested from these regions on the other side. In contrast to expectations, both erupting and functioning molars had reticular fibrolamellar structure in alveolar bone adjacent to M1. However, the woven bone matrix in older pigs was thicker and had denser primary osteons. Gene expression data and osteoclast cell counts showed a tendency for more bone resorptive activity near the molars than at distant sites, but no differences between eruptive stages. Thus, although resorption does occur, it is not a primary mechanism in the transition in alveolar bone from eruption to function. Incremental growth of existing woven bone and filling in of primary osteons within the mineralized scaffold generated the fortification necessary to support an erupted and functioning tooth. PMID:21434979

Bone morphogenetic protein-mediated interaction of periosteum and diaphysis. Citric acid and other factors influencing the generation of parosteal bone.

PubMed

Kübler, N; Urist, M R

1990-09-01

In rabbits, after long-bone growth is complete and the cambium layer regresses, mesenchymal-type cells with embryonic potential (competence) for bone development persist in the adventitial layer of periosteum. These cells are not determined osteoprogenitor cells (stem cells) because bone tissue differentiation does not occur when adult periosteum is transplanted into a heterotopic site. In this respect, adventitial cells differ from bone marrow stroma cells. In a parosteal orthotopic site in the space between the adult periosteum and diaphysis, implants of bone morphogenetic protein (BMP) and associated noncollagenous proteins (BMP/NCP) induce adventitia and adjacent muscle connective-tissue-derived cells to switch from a fibrogenetic to a chondroosteoprogenetic pattern of bone development. The quantity of induced bone is proportional to the dose of BMP/NCP in the range from 10 to 50 mg; immature rabbits produced larger deposits than mature rabbits in response to BMP/NCP. Preoperative local intramuscular injections of citric, edetic, or hyaluronic acids in specified concentrations markedly enhanced subperiosteal BMP/NCP-induced bone formation. The quantity of bovine or human BMP/NCP-induced bone formation in rabbits is also increased by very low-dose immunosuppression but not by bone mineral, tricalcium phosphate ceramic, inorganic calcium salts, or various space-occupying, unspecific chemical irritants. Although composities of BMP/NCP and allogeneic rabbit tendon collagen increased the quantity of bone in a parosteal site, in a heterotopic site the composite failed to induce bone formation. In a parosteal site, the conditions permitting BMP/NCP-induced bone formation develop, and the end product of the morphogenetic response is a duplicate diaphysis. How BMP reactivates the morphogenetic process in postfetal mesenchymal-type adventitial cells persisting in adult periosteum (including adjacent muscle attachments) is not known.

Grouper: A Compact, Streamable Triangle Mesh Data Structure.

PubMed

Luffel, Mark; Gurung, Topraj; Lindstrom, Peter; Rossignac, Jarek

2013-05-08

We present Grouper: an all-in-one compact file format, random-access data structure, and streamable representation for large triangle meshes. Similarly to the recently published SQuad representation, Grouper represents the geometry and connectivity of a mesh by grouping vertices and triangles into fixed-size records, most of which store two adjacent triangles and a shared vertex. Unlike SQuad, however, Grouper interleaves geometry with connectivity and uses a new connectivity representation to ensure that vertices and triangles can be stored in a coherent order that enables memory-efficient sequential stream processing. We present a linear-time construction algorithm that allows streaming out Grouper meshes using a small memory footprint while preserving the initial ordering of vertices. As part of this construction, we show how the problem of assigning vertices and triangles to groups reduces to a well-known NP-hard optimization problem, and present a simple yet effective heuristic solution that performs well in practice. Our array-based Grouper representation also doubles as a triangle mesh data structure that allows direct access to vertices and triangles. Storing only about two integer references per triangle, Grouper answers both incidence and adjacency queries in amortized constant time. Our compact representation enables data-parallel processing on multicore computers, instant partitioning and fast transmission for distributed processing, as well as efficient out-of-core access.

Modelling the temperature evolution of bone under high intensity focused ultrasound

NASA Astrophysics Data System (ADS)

ten Eikelder, H. M. M.; Bošnački, D.; Elevelt, A.; Donato, K.; Di Tullio, A.; Breuer, B. J. T.; van Wijk, J. H.; van Dijk, E. V. M.; Modena, D.; Yeo, S. Y.; Grüll, H.

2016-02-01

Magnetic resonance-guided high intensity focused ultrasound (MR-HIFU) has been clinically shown to be effective for palliative pain management in patients suffering from skeletal metastasis. The underlying mechanism is supposed to be periosteal denervation caused by ablative temperatures reached through ultrasound heating of the cortex. The challenge is exact temperature control during sonication as MR-based thermometry approaches for bone tissue are currently not available. Thus, in contrast to the MR-HIFU ablation of soft tissue, a thermometry feedback to the HIFU is lacking, and the treatment of bone metastasis is entirely based on temperature information acquired in the soft tissue adjacent to the bone surface. However, heating of the adjacent tissue depends on the exact sonication protocol and requires extensive modelling to estimate the actual temperature of the cortex. Here we develop a computational model to calculate the spatial temperature evolution in bone and the adjacent tissue during sonication. First, a ray-tracing technique is used to compute the heat production in each spatial point serving as a source term for the second part, where the actual temperature is calculated as a function of space and time by solving the Pennes bio-heat equation. Importantly, our model includes shear waves that arise at the bone interface as well as all geometrical considerations of transducer and bone geometry. The model was compared with a theoretical approach based on the far field approximation and an MR-HIFU experiment using a bone phantom. Furthermore, we investigated the contribution of shear waves to the heat production and resulting temperatures in bone. The temperature evolution predicted by our model was in accordance with the far field approximation and agreed well with the experimental data obtained in phantoms. Our model allows the simulation of the HIFU treatments of bone metastasis in patients and can be extended to a planning tool prior to MR

Correlation between ultrasound velocity and densitometry in fresh and demineralized cortical bone

PubMed Central

de Mesquita, Alessandro Queiroz; Barbieri, Giuliano; Barbieri, Claudio Henrique

2016-01-01

OBJECTIVE: To compare ultrasound propagation velocity with densitometry in the diaphyseal compact cortical bone of whole sheep metatarsals. METHODS: The transverse ultrasound velocity and bone mineral density of 5-cm-long diaphyseal bone segments were first measured. The bone segments were then divided into four groups of 15 segments each and demineralized in an aqueous 0.5 N hydrochloric acid solution for 6, 12, 24 or 36 hours. All measurements were repeated after demineralization for each time duration and the values measured before and after demineralization were compared. RESULTS: Ultrasound velocity and bone mineral density decreased with demineralization time, and most differences in the pre- and post-demineralization values within each group and between groups were significant: A moderate correlation coefficient (r=0.75956) together with a moderate agreement was determined between both post-demineralization parameters, detected by the Bland-Altman method. CONCLUSION: We conclude that both ultrasound velocity and bone mineral density decrease as a result of demineralization, thus indicating that bone mineral content is of great importance for maintaining the acoustic parameters of cortical bone, as observed for cancellous bone. Ultrasound velocity can be used to evaluate both compact cortical bone quality and bone mineral density. PMID:27982167

[Scanning electron microscopy of heat-damaged bone tissue].

PubMed

Harsanyl, L

1977-02-01

Parts of diaphyses of bones were exposed to high temperature of 200-1300 degrees C. Damage to the bone tissue caused by the heat was investigated. The scanning electron microscopic picture seems to be characteristic of the temperature applied. When the bones heated to the high temperature of 700 degrees C characteristic changes appear on the periostal surface, higher temperatura on the other hand causes damage to the compact bone tissue and can be observed on the fracture-surface. Author stresses the importance of this technique in the legal medicine and anthropology.

Determination of spatial distribution of increase in bone temperature during drilling by infrared thermography: preliminary report.

PubMed

Augustin, Goran; Davila, Slavko; Udiljak, Toma; Vedrina, Denis Stjepan; Bagatin, Dinko

2009-05-01

During the drilling of the bone, the temperature could increase above 47 degrees C and cause irreversible osteonecrosis. The spatial distribution of increase in bone temperature could only be presumed using several thermocouples around the drilling site. The aim of this study was to use infrared thermographic camera for determination of spatial distribution of increase in bone temperature during drilling. One combination of drill parameters was used (drill diameter 4.5 mm; drill speed 1,820 rpm; feed-rate 84 mm/min; drill point angle 100 degrees) without external irrigation on room temperature of 26 degrees C. The increase in bone temperature during drilling was analyzed with infrared thermographic camera in two perpendicular planes. Thermographic pictures were taken before drilling, during drilling with measurement of maximal temperature values and after extraction of the drill from the bone. The thermographic picture shows that the increase in bone temperature has irregular shape with maximal increase along cortical bone, which is the most compact component of the bone. The width of this area with the temperature above critical level is three times broader than the width of cortical bone. From the front, the distribution of increase in bone temperature follows the form of the cortical bone (segment of a ring), which is the most compact part and causes the highest resistance to drilling and subsequent friction. Thermography showed that increase in bone temperature spreads through cortical bone, which is the most compact and dense part, and generates highest frictional heat during drilling. The medullar cavity, because of its gelatinous structure, contributes only to thermal dissipation.

DNA survival and physical and histological properties of heat-induced alterations in burnt bones.

PubMed

Imaizumi, K; Taniguchi, K; Ogawa, Y

2014-05-01

During forensic casework, it is vital to be able to obtain valuable information from burnt bone fragments to ascertain the identity of the victim. Here, we report the findings of an experimental study on burnt bovine compact bone segments. Compact bones were cut to size and heated in an electric furnace at a temperature range of 100–1,100 °C with 100 °C increments. Heat-induced alterations to the bone color,weight, volume, and density were monitored using gross morphology and micro-focus X-ray computed tomography.We found that the increase in temperature caused the color of the compact bones to change in order of yellow, brown, gray,and white. In contrast to the weight reduction that occurred immediately after burning, we measured no significant reduction in volume even at 600 °C; however, volume reduced drastically once the temperature reached 700 °C. Light microscopic histological observations of burnt bone revealed heat induced alterations such as cracking and separation of the osteons at higher temperatures. In addition to these findings,we sought to examine the survival of DNA in the burnt bones using polymerase chain reaction of mitochondrial DNA. No amplification was found in the specimens burnt at 250 °C or higher, indicating the likely difficulty in testing the DNA of burnt bones from forensic casework. The results of this study will enable an estimation of the burning temperatures of burnt bones found in forensic cases and will provide an important framework with which to interpret data obtained during anthropological testing and DNA typing.

Water-level altitudes 2014 and water-level changes in the Chicot, Evangeline, and Jasper aquifers and compaction 1973-2013 in the Chicot and Evangeline aquifers, Houston-Galveston region, Texas

USGS Publications Warehouse

Kasmarek, Mark C.; Johnson, Michaela R.; Ramage, Jason K.

2014-01-01

Compaction of subsurface sediments (mostly in the fine-grained clay and silt layers) composing the Chicot and Evangeline aquifers was recorded continuously by using analog technology at the 13 borehole extensometers at 11 sites that were either activated or installed between 1973 and 1980. For the period of record beginning in 1973 (or later depending on activation or installation date) and ending in December 2013, measured cumulative compaction at the 13 extensometers ranged from 0.100 ft at the Texas City-Moses Lake extensometer to 3.654 ft at the Addicks extensometer. The rate of compaction varies from site to site because of differences in rates of groundwater withdrawal in the areas adjacent to each extensometer site and differences among sites in the ratios of clay, silt, and sand and compressibility of the subsurface sediments. Therefore, it is not appropriate to extrapolate or infer a rate of compaction for an adjacent area on the basis of the rate of compaction measured at nearby extensometers.

Study of the suitability of a commercial hydroxyapatite powder to obtain sintered compacts for medical applications

NASA Astrophysics Data System (ADS)

Palacio, C.; Jaramillo, D.; Correa, S.; Arroyave, M.

2017-06-01

Hydroxyapatite (HA) is a material widely used by the medical community due to its Ca/P ratio is comparable to the Ca/P ratio of bones and teeth, which promotes osteoinduction and osteoconduction processes when in contact with bone tissue, either as volume piece or coating. This work focuses on studying the quality of the commercial HA powder MKnano-#MKN-HXAP-S12 µm, after processing, to obtain sintered compact discs with suitable physical and chemical characteristics for implants applications. The HA powder was processed through calcination, grinding, pressing and sintering to evaluate the effect of such as procedures in the compacts dics quality. The raw powder was characterized by laser diffraction, SEM, XRF, XRD, TGA and DSC while the characteristics of the obtained compact discs were determined by dilatometry and XRD to identify the sintering temperature range, constituent phases, the amorphous content and the crystallinity degree, parameters that allow determining their suitability for implants applications. Although, it was not possible to obtain sintered compacts with the suitable chemical composition and without fractures, this work allowed to identify the parameters that determine the suitability of a HA powder to obtain sintered compacts for medical applications, as well as the characterization protocol that allows the evaluation of such parameters.

Increased compactibility of acetames after roll compaction.

PubMed

Kuntz, Theresia; Schubert, Martin A; Kleinebudde, Peter

2011-01-01

A common technique for manufacturing granules in a continuous way is the combination of roll compaction and subsequent milling. Roll compaction can considerably impact tableting performance of a material. The purpose of this study was to investigate the influence of roll compaction/dry granulation on the compaction behavior of acetames, a class of active pharmaceutical substances, which are mainly used for the treatment of central nervous diseases. Some representatives of acetames were roll compacted and then compressed into tablets. Compactibility of granules was compared with the compaction behavior of the directly compressed drug powders. In contrast to many other materials, the roll compaction step induced an increase in compactibility for all investigated acetames. Specific surface areas of the untreated and the roll compacted drugs were determined by nitrogen adsorption. The raise in compactibility observed was accompanied by an increase in specific surface area during roll compaction. Copyright © 2010 Elsevier B.V. All rights reserved.

Long-Bone Injury Criteria for Use with the Articulated Total Body Model

DTIC Science & Technology

1981-01-01

bone - human, canine, bovine, etc.; condition of bone - dry, wet , embalmed , fresh; subject variations - height, weight, health, sex, age, etc; whole bone...stress strain curves ob- tained by McElhaney for various strain rates in compression. This is for embalmed human compact bone. Ultimate stress, ultimate...reported for fresh human bone of 25,000 psi (see Table 1). Recall that the McElhaney data is from embalmed subjects. If it is assumed, for lack of any real

Signaling pathways effecting crosstalk between cartilage and adjacent tissues: Seminars in cell and developmental biology: The biology and pathology of cartilage.

PubMed

Maes, Christa

2017-02-01

Endochondral ossification, the mechanism responsible for the development of the long bones, is dependent on an extremely stringent coordination between the processes of chondrocyte maturation in the growth plate, vascular expansion in the surrounding tissues, and osteoblast differentiation and osteogenesis in the perichondrium and the developing bone center. The synchronization of these processes occurring in adjacent tissues is regulated through vigorous crosstalk between chondrocytes, endothelial cells and osteoblast lineage cells. Our knowledge about the molecular constituents of these bidirectional communications is undoubtedly incomplete, but certainly some signaling pathways effective in cartilage have been recognized to play key roles in steering vascularization and osteogenesis in the perichondrial tissues. These include hypoxia-driven signaling pathways, governed by the hypoxia-inducible factors (HIFs) and vascular endothelial growth factor (VEGF), which are absolutely essential for the survival and functioning of chondrocytes in the avascular growth plate, at least in part by regulating the oxygenation of developing cartilage through the stimulation of angiogenesis in the surrounding tissues. A second coordinating signal emanating from cartilage and regulating developmental processes in the adjacent perichondrium is Indian Hedgehog (IHH). IHH, produced by pre-hypertrophic and early hypertrophic chondrocytes in the growth plate, induces the differentiation of adjacent perichondrial progenitor cells into osteoblasts, thereby harmonizing the site and time of bone formation with the developmental progression of chondrogenesis. Both signaling pathways represent vital mediators of the tightly organized conversion of avascular cartilage into vascularized and mineralized bone during endochondral ossification. Copyright © 2016. Published by Elsevier Ltd.

An Assessment of Bone Fluoride and Osteosarcoma

PubMed Central

Kim, F.M.; Hayes, C.; Williams, P.L.; Whitford, G.M.; Joshipura, K.J.; Hoover, R.N.; Douglass, C.W.

2011-01-01

The association between fluoride and risk for osteosarcoma is controversial. The purpose of this study was to determine if bone fluoride levels are higher in individuals with osteosarcoma. Incident cases of osteosarcoma (N = 137) and tumor controls (N = 51) were identified by orthopedic physicians, and segments of tumor-adjacent bone and iliac crest bone were analyzed for fluoride content. Logistic regression adjusted for age and sex and potential confounders of osteosarcoma was used to estimate odds ratios (OR) and 95% confidence intervals (CI). There was no significant difference in bone fluoride levels between cases and controls. The OR adjusted for age, gender, and a history of broken bones was 1.33 (95% CI: 0.56-3.15). No significant association between bone fluoride levels and osteosarcoma risk was detected in our case-control study, based on controls with other tumor diagnoses. PMID:21799046

Vascular Spaces in Compact Bone: A Technique to Correct a Common Misinterpretation of Structure

ERIC Educational Resources Information Center

Locke, M.; Dean, Rob L.

2003-01-01

Old bones are often discolored by the grime that infiltrates spaces in the matrix once occupied by blood vessels. This suggested that allowing dry bone to absorb colorants might be a useful way to show the three dimensional complexity of bone vascularization. The authors have developed a simple way to show blood vessels spaces in bone at a glance…

Bone response adjacent to calcium phosphate electrostatic spray deposition coated implants: an experimental study in goats.

PubMed

Manders, Peter J D; Wolke, Joop G C; Jansen, John A

2006-10-01

A new technique to deposit calcium phosphate (CaP) coatings onto titanium substrates has been developed recently. This electrostatic spray deposition (ESD) technique seems to be very promising. It appears to have clinical advantages such as an inexpensive and simple set-up, high deposition efficiency and the possibility to synthesize layers with a defined surface morphology. The aim of this study was to examine biological properties and osteoconductivity of ESD CaP coatings when inserted into the femoral condyle of a goat. Twenty-four implants with two gaps, i.e. 1 or 2 mm, were inserted into the femoral condyles of six goats. The implants were coated on one side with either a commercially available plasma-sprayed hydroxyapatite (HAPS) coating or an ESD carbonate apatite (CAESD) coating. The other side of the implant was always left uncoated (Ti). Twelve weeks after implantation the animals were sacrificed and the characteristics of bone ingrowth and bone contact were evaluated. At 3 months, histological and quantitative histomorphometrical measurements demonstrated more bone ingrowth and bone contact for coated sites as compared with uncoated sites. Statistical testing revealed that for both the 1 and 2 mm gaps HAPS (plasma-sprayed hydroxyapatite) as well as CAESD (ESD carbonate apatite) -coated surfaces always had a significantly higher (P<0.05) amount of bone contact than uncoated Ti surfaces. On HAPS surfaces always significantly more bone was present than on CAESD surfaces. Further statistical testing revealed a significant difference in bone ingrowth between the HAPS as well as CAESD and Ti 1+2 mm gap specimens (P<0.05). Further, HAPS 1 mm gaps showed more bone ingrowth than CAESD 1 mm gaps. No significant difference existed between HAPS and CAESD 2 mm gaps. On the basis of our observations, we conclude that the used ESD technique is a promising new method to deposit CaP coatings onto titanium substrates. On the other hand, plasma-spray HA-coated implants

Functional anatomy of the nasal bones and adjacent structures. Consequences for nasal surgery.

PubMed

Popko, M; Verlinde-Schellekens, S A M W; Huizing, E H; Bleys, R L A W

2018-03-01

The periosteum of the nasal bones, the periosteal-perichondrial nasal envelope, and the cartilaginous support of the bony vault were studied in serial coronal sections of four human cadaver noses. To differentiate between the various tissue components, the sections were stained according to Mallory-Cason and Verhoeff-Van Gieson stain. The results demonstrated: 1. the presence of clearly distinguishable layers of the periosteum covering the nasal bones; 2. the presence of a continuous periosteal-perichondrial covering of the bony and cartilaginous nasal vaults; 3. the way the cartilaginous support of the bony vault is constructed. The findings described in the present study may have clinical relevance in nasal surgery.

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.

Bone structure of the temporo-mandibular joint in the individuals aged 18-25.

PubMed

Parafiniuk, M; Gutsch-Trepka, A; Trepka, S; Sycz, K; Wolski, S; Parafiniuk, W

1998-01-01

Osteohistometric studies were performed in 15 female and 15 male cadavers aged 18-25. Condyloid process and right and left acetabulum of the temporo-mandibular joint have been studied. Density has been investigated using monitor screen linked with microscope (magnification 80x). Density in the spongy part of the condyloid process was 26.67-26.77%; in the subchondrial layer--72.13-72.72%, and in the acetabular wall 75.03-75.91%. Microscopic structure of the bones of the temporo-mandibular joint revealed no differences when compared with images of compact and cancellous bone shown in the histology textbooks. Sex and the side of the body had no influence on microscopic image and proportional bone density. Isles of chondrocytes in the trabeculae of the spongy structure of the condyloid process were found in 4 cases and isles of the condensed bone resembling the compact pattern in 7 cases.

Antimicrobial photodynamic inactivation of Staphylococcus aureus biofilms in bone specimens using methylene blue, toluidine blue ortho and malachite green: An in vitro study.

PubMed

Rosa, Luciano Pereira; da Silva, Francine Cristina; Nader, Sumaia Alves; Meira, Giselle Andrade; Viana, Magda Souza

2015-05-01

To evaluate the in vitro effectiveness of APDI with a 660 nm laser combined with methylene blue (MB), toluidine blue ortho (TBO) and malachite green (MG) dyes to inactivate Staphylococcus aureus (ATCC 25923) biofilms in compact and cancellous bone specimens. Eighty specimens of compact and 80 of cancellous bone were contaminated with a standard suspension of the microorganism and incubated for 14 days at 37°C to form biofilms. After this period, the specimens were divided into groups (n=10) according to established treatment: PS-L- (control - no treatment); PSmb+L-, PStbo+L-, PSmg+L- (only MB, TBO or MG for 5 min in the dark); PS-L+ (only laser irradiation for 180 s); and APDImb, APDItbo and APDImg (APDI with MB, TBO or MG for 180 s). The findings were statistically analyzed by ANOVA at 5% significance levels. All experimental treatments showed significant reduction of log CFU/mL S. aureus biofilms when compared with the control group for compact and cancellous bones specimens; the APDI group's treatment was more effective. The APDI carried out for the compact specimens showed better results when compared with cancellous specimens at all times of application. For the group of compact bone, APDImg showed greater reductions in CFU/mL (4.46 log 10). In the group of cancellous bone, the greatest reductions were found in the APDImb group (3.06 log 10). APDI with methylene blue, toluidine blue ortho and malachite green dyes and a 660 nm laser proved to be effective in the inactivation of S. aureus biofilms formed in compact and cancellous bone. Copyright © 2015 Elsevier Ltd. All rights reserved.

Grouper: a compact, streamable triangle mesh data structure.

PubMed

Luffel, Mark; Gurung, Topraj; Lindstrom, Peter; Rossignac, Jarek

2014-01-01

We present Grouper: an all-in-one compact file format, random-access data structure, and streamable representation for large triangle meshes. Similarly to the recently published SQuad representation, Grouper represents the geometry and connectivity of a mesh by grouping vertices and triangles into fixed-size records, most of which store two adjacent triangles and a shared vertex. Unlike SQuad, however, Grouper interleaves geometry with connectivity and uses a new connectivity representation to ensure that vertices and triangles can be stored in a coherent order that enables memory-efficient sequential stream processing. We present a linear-time construction algorithm that allows streaming out Grouper meshes using a small memory footprint while preserving the initial ordering of vertices. As a part of this construction, we show how the problem of assigning vertices and triangles to groups reduces to a well-known NP-hard optimization problem, and present a simple yet effective heuristic solution that performs well in practice. Our array-based Grouper representation also doubles as a triangle mesh data structure that allows direct access to vertices and triangles. Storing only about two integer references per triangle--i.e., less than the three vertex references stored with each triangle in a conventional indexed mesh format--Grouper answers both incidence and adjacency queries in amortized constant time. Our compact representation enables data-parallel processing on multicore computers, instant partitioning and fast transmission for distributed processing, as well as efficient out-of-core access. We demonstrate the versatility and performance benefits of Grouper using a suite of example meshes and processing kernels.

Grouper: A Compact, Streamable Triangle Mesh Data Structure

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

Luffel, Mark; Gurung, Topraj; Lindstrom, Peter

2014-01-01

Here, we present Grouper: an all-in-one compact file format, random-access data structure, and streamable representation for large triangle meshes. Similarly to the recently published SQuad representation, Grouper represents the geometry and connectivity of a mesh by grouping vertices and triangles into fixed-size records, most of which store two adjacent triangles and a shared vertex. Unlike SQuad, however, Grouper interleaves geometry with connectivity and uses a new connectivity representation to ensure that vertices and triangles can be stored in a coherent order that enables memory-efficient sequential stream processing. We also present a linear-time construction algorithm that allows streaming out Grouper meshesmore » using a small memory footprint while preserving the initial ordering of vertices. In this construction, we show how the problem of assigning vertices and triangles to groups reduces to a well-known NP-hard optimization problem, and present a simple yet effective heuristic solution that performs well in practice. Our array-based Grouper representation also doubles as a triangle mesh data structure that allows direct access to vertices and triangles. Storing only about two integer references per triangle-i.e., less than the three vertex references stored with each triangle in a conventional indexed mesh format-Grouper answers both incidence and adjacency queries in amortized constant time. Our compact representation enables data-parallel processing on multicore computers, instant partitioning and fast transmission for distributed processing, as well as efficient out-of-core access. We demonstrate the versatility and performance benefits of Grouper using a suite of example meshes and processing kernels.« less

Sacroiliac Joint Fusion Minimally Affects Adjacent Lumbar Segment Motion: A Finite Element Study

PubMed Central

Kiapour, Ali; Yerby, Scott A.; Goel, Vijay K.

2015-01-01

Background Adjacent segment disease is a recognized consequence of fusion in the spinal column. Fusion of the sacroiliac joint is an effective method of pain reduction. Although effective, the consequences of sacroiliac joint fusion and the potential for adjacent segment disease for the adjacent lumbar spinal levels is unknown. The objective of this study was to quantify the change in range of motion of the sacroiliac joint and the adjacent lumbar spinal motion segments due to sacroiliac joint fusion and compare these changes to previous literature to assess the potential for adjacent segment disease in the lumbar spine. Methods An experimentally validated finite element model of the lumbar spine and pelvis was used to simulate a fusion of the sacroiliac joint using three laterally placed triangular implants (iFuse Implant System, SI-BONE, Inc., San Jose, CA). The range of motion of the sacroiliac joint and the adjacent lumbar spinal motion segments were calculated using a hybrid loading protocol and compared with the intact range of motion in flexion, extension, lateral bending, and axial rotation. Results The range of motions of the treated sacroiliac joints were reduced in flexion, extension, lateral bending, and axial rotation, by 56.6%, 59.5%, 27.8%, and 53.3%, respectively when compared with the intact condition. The stiffening of the sacroiliac joint resulted in increases at the adjacent lumbar motion segment (L5-S1) for flexion, extension, lateral bending, and axial rotation, of 3.0%, 3.7%, 1.1%, and 4.6%, respectively. Conclusions Fusion of the sacroiliac joint resulted in substantial (> 50%) reductions in flexion, extension, and axial rotation of the sacroiliac joint with minimal (< 5%) increases in range of motion in the lumbar spine. Although the predicted increases in lumbar range of motion are minimal after sacroiliac joint fusion, the long-term clinical results remain to be investigated. PMID:26767156

Sacroiliac Joint Fusion Minimally Affects Adjacent Lumbar Segment Motion: A Finite Element Study.

PubMed

Lindsey, Derek P; Kiapour, Ali; Yerby, Scott A; Goel, Vijay K

2015-01-01

Adjacent segment disease is a recognized consequence of fusion in the spinal column. Fusion of the sacroiliac joint is an effective method of pain reduction. Although effective, the consequences of sacroiliac joint fusion and the potential for adjacent segment disease for the adjacent lumbar spinal levels is unknown. The objective of this study was to quantify the change in range of motion of the sacroiliac joint and the adjacent lumbar spinal motion segments due to sacroiliac joint fusion and compare these changes to previous literature to assess the potential for adjacent segment disease in the lumbar spine. An experimentally validated finite element model of the lumbar spine and pelvis was used to simulate a fusion of the sacroiliac joint using three laterally placed triangular implants (iFuse Implant System, SI-BONE, Inc., San Jose, CA). The range of motion of the sacroiliac joint and the adjacent lumbar spinal motion segments were calculated using a hybrid loading protocol and compared with the intact range of motion in flexion, extension, lateral bending, and axial rotation. The range of motions of the treated sacroiliac joints were reduced in flexion, extension, lateral bending, and axial rotation, by 56.6%, 59.5%, 27.8%, and 53.3%, respectively when compared with the intact condition. The stiffening of the sacroiliac joint resulted in increases at the adjacent lumbar motion segment (L5-S1) for flexion, extension, lateral bending, and axial rotation, of 3.0%, 3.7%, 1.1%, and 4.6%, respectively. Fusion of the sacroiliac joint resulted in substantial (> 50%) reductions in flexion, extension, and axial rotation of the sacroiliac joint with minimal (< 5%) increases in range of motion in the lumbar spine. Although the predicted increases in lumbar range of motion are minimal after sacroiliac joint fusion, the long-term clinical results remain to be investigated.

Compact cyclone filter train for radiological and hazardous environments

DOEpatents

Bench, T.R.

1998-04-28

A compact cyclone filter train is disclosed for the removal of hazardous and radiological particles from a gaseous fluid medium. This filter train permits a small cyclone separator to be used in a very small space envelope due to the arrangement of the filter housing adjacent to the separator with the cyclone separator and the filters mounted on a plate. The entire unit will have a hoist connection at the center of gravity so that the entire unit including the separator, the filters, and the base can be lifted and repositioned as desired. 3 figs.

Compact cyclone filter train for radiological and hazardous environments

DOEpatents

Bench, Thomas R.

1998-01-01

A compact cyclone filter train for the removal of hazardous and radiologi particles from a gaseous fluid medium which permits a small cyclone separator to be used in a very small space envelope due to the arrangement of the filter housing adjacent to the separator with the cyclone separator and the filters mounted on a plate. The entire unit will have a hoist connection at the center of gravity so that the entire unit including the separator, the filters, and the base can be lifted and repositioned as desired.

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

Functionally deficient mesenchymal stem cells reside in the bone marrow niche with M2-macrophages and amyloid-β protein adjacent to loose total joint implants.

PubMed

Margulies, Bryan S; DeBoyace, Sean D; Parsons, Adrienne M; Policastro, Connor G; Ee, Jessica S S; Damron, Timothy S

2015-05-01

We sought to demonstrate whether there is a difference in the local mesenchymal stem cells (MSC) niche obtained from patients undergoing their first total joint replacement surgery versus those patients undergoing a revision surgery for an failing total joint implant. Bone marrow aspirates collected from patients undergoing revision total joint arthroplasty were observed to be less clonal and the expression of PDGFRα, CD51, ALCAM, endoglin, CXCL12, nestin, and nucleostemin were decreased. Revision MSC were also less able to commit to an osteoblast-lineage or an adipocyte-lineage. Further, in revision MSC, OPG, and IL6 expression were increased. Monocytes, derived from revision whole marrow aspirates, were less capable of differentiating into osteoclasts, the cells implicated in the pathologic degradation of bone. Osteoclasts were also not observed in tissue samples collected adjacent to the implants of revision patients; however, the alternatatively activated M2-macrophage phenotype was observed in parallel with pathologic accumulations of amyloid-β, τ-protien and 3-nitrotyrosine. Despite the limited numbers of patients examined, our data suggest that nucleostemin may be a useful functional marker for MSC while the observation of M2-macrophage infiltration around the implant lays the foundation for future investigation into a novel mechanism that we propose is associated with loose total joint implants. © 2014 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

Multiple congenital brachymetatarsia. A one-stage combined shortening and lengthening procedure without iliac bone graft.

PubMed

Kim, J S; Baek, G H; Chung, M S; Yoon, P W

2004-09-01

We performed nine metatarsal and three proximal phalangeal lengthenings in five patients with congenital brachymetatarsia of the first and one or two other metatarsal bones, by a one-stage combined shortening and lengthening procedure using intercalcary autogenous bone grafts from adjacent shortened metatarsal bones. Instead of the isolated lengthening of the first and the other metatarsal bones, we shortened the adjacent normal metatarsal and used the excised bone to lengthen the short toes, except for the great toe, to restore the normal parabola. One skin incision was used. All the operations were performed bilaterally and the patients were followed up for a mean period of 69.5 months (29 to 107). They all regained a nearly normal parabola and were satisfied with the cosmetic results. Our technique is straightforward and produces good cosmetic results. Satisfactory, bony union is achieved, morbidity is low, and no additional surgery is required for the removal of metal implants.

Bone Inner Structure Suggests Increasing Aquatic Adaptations in Desmostylia (Mammalia, Afrotheria)

PubMed Central

Hayashi, Shoji; Houssaye, Alexandra; Nakajima, Yasuhisa; Chiba, Kentaro; Ando, Tatsuro; Sawamura, Hiroshi; Inuzuka, Norihisa; Kaneko, Naotomo; Osaki, Tomohiro

2013-01-01

Background The paleoecology of desmostylians has been discussed controversially with a general consensus that desmostylians were aquatic or semi-aquatic to some extent. Bone microanatomy can be used as a powerful tool to infer habitat preference of extinct animals. However, bone microanatomical studies of desmostylians are extremely scarce. Methodology/Principal Findings We analyzed the histology and microanatomy of several desmostylians using thin-sections and CT scans of ribs, humeri, femora and vertebrae. Comparisons with extant mammals allowed us to better understand the mode of life and evolutionary history of these taxa. Desmostylian ribs and long bones generally lack a medullary cavity. This trait has been interpreted as an aquatic adaptation among amniotes. Behemotops and Paleoparadoxia show osteosclerosis (i.e. increase in bone compactness), and Ashoroa pachyosteosclerosis (i.e. combined increase in bone volume and compactness). Conversely, Desmostylus differs from these desmostylians in displaying an osteoporotic-like pattern. Conclusions/Significance In living taxa, bone mass increase provides hydrostatic buoyancy and body trim control suitable for poorly efficient swimmers, while wholly spongy bones are associated with hydrodynamic buoyancy control in active swimmers. Our study suggests that all desmostylians had achieved an essentially, if not exclusively, aquatic lifestyle. Behemotops, Paleoparadoxia and Ashoroa are interpreted as shallow water swimmers, either hovering slowly at a preferred depth, or walking on the bottom, and Desmostylus as a more active swimmer with a peculiar habitat and feeding strategy within Desmostylia. Therefore, desmostylians are, with cetaceans, the second mammal group showing a shift from bone mass increase to a spongy inner organization of bones in their evolutionary history. PMID:23565143

Mandibular bone changes in 24 years and skeletal fracture prediction.

PubMed

Jonasson, G; Sundh, V; Hakeberg, M; Hassani-Nejad, A; Lissner, L; Ahlqwist, M

2013-03-01

The objectives of the investigation were to describe changes in mandibular bone structure with aging and to compare the usefulness of cortical and trabecular bone for fracture prediction. From 1968 to 1993, 1,003 women were examined. With the help of panoramic radiographs, cortex thickness was measured and cortex was categorized as: normal, moderately, or severely eroded. The trabeculation was assessed as sparse, mixed, or dense. Visually, the mandibular compact and trabecular bone transformed gradually during the 24 years. The compact bone became more porous, the intertrabecular spaces increased, and the radiographic image of the trabeculae seemed less mineralized. Cortex thickness increased up to the age of 50 and decreased significantly thereafter. At all examinations, the sparse trabeculation group had more fractures (71-78 %) than the non-sparse group (27-31 %), whereas the severely eroded compact group showed more fractures than the less eroded groups only in 1992/1993, 24 years later. Sparse trabecular pattern was associated with future fractures both in perimenopausal and older women (relative risk (RR), 1.47-4.37) and cortical erosion in older women (RR, 1.35-1.55). RR for future fracture associated with a severely eroded cortex increased to 4.98 for cohort 1930 in 1992/1993. RR for future fracture associated with sparse trabeculation increased to 11.43 for cohort 1922 in 1992/1993. Dental radiographs contain enough information to identify women most at risk of future fracture. When observing sparse mandibular trabeculation, dentists can identify 40-69 % of women at risk for future fractures, depending on participant age at examination.

Processing strategies for smart electroconductive carbon nanotube-based bioceramic bone grafts

NASA Astrophysics Data System (ADS)

Mata, D.; Oliveira, F. J.; Ferreira, N. M.; Araújo, R. F.; Fernandes, A. J. S.; Lopes, M. A.; Gomes, P. S.; Fernandes, M. H.; Silva, R. F.

2014-04-01

Electroconductive bone grafts have been designed to control bone regeneration. Contrary to polymeric matrices, the translation of the carbon nanotube (CNT) electroconductivity into oxide ceramics is challenging due to the CNT oxidation during sintering. Sintering strategies involving reactive-bed pressureless sintering (RB + P) and hot-pressing (HP) were optimized towards prevention of CNT oxidation in glass/hydroxyapatite (HA) matrices. Both showed CNT retentions up to 80%, even at 1300 °C, yielding an increase of the electroconductivity in ten orders of magnitude relative to the matrix. The RB + P CNT compacts showed higher electroconductivity by ˜170% than the HP ones due to the lower damage to CNTs of the former route. Even so, highly reproducible conductivities with statistical variation below 5% and dense compacts up to 96% were only obtained by HP. The hot-pressed CNT compacts possessed no acute toxicity in a human osteoblastic cell line. A normal cellular adhesion and a marked orientation of the cell growth were observed over the CNT composites, with a proliferation/differentiation relationship favouring osteoblastic functional activity. These sintering strategies offer new insights into the sintering of electroconductive CNT containing bioactive ceramics with unlimited geometries for electrotherapy of the bone tissue.

Dilatational band formation in bone

PubMed Central

Poundarik, Atharva A.; Diab, Tamim; Sroga, Grazyna E.; Ural, Ani; Boskey, Adele L.; Gundberg, Caren M.; Vashishth, Deepak

2012-01-01

Toughening in hierarchically structured materials like bone arises from the arrangement of constituent material elements and their interactions. Unlike microcracking, which entails micrometer-level separation, there is no known evidence of fracture at the level of bone’s nanostructure. Here, we show that the initiation of fracture occurs in bone at the nanometer scale by dilatational bands. Through fatigue and indentation tests and laser confocal, scanning electron, and atomic force microscopies on human and bovine bone specimens, we established that dilatational bands of the order of 100 nm form as ellipsoidal voids in between fused mineral aggregates and two adjacent proteins, osteocalcin (OC) and osteopontin (OPN). Laser microdissection and ELISA of bone microdamage support our claim that OC and OPN colocalize with dilatational bands. Fracture tests on bones from OC and/or OPN knockout mice (OC−/−, OPN−/−, OC-OPN−/−;−/−) confirm that these two proteins regulate dilatational band formation and bone matrix toughness. On the basis of these observations, we propose molecular deformation and fracture mechanics models, illustrating the role of OC and OPN in dilatational band formation, and predict that the nanometer scale of tissue organization, associated with dilatational bands, affects fracture at higher scales and determines fracture toughness of bone. PMID:23129653

Strontium-90 concentration measurements in human bones and teeth in Greece.

PubMed

Stamoulis, K C; Assimakopoulos, P A; Ioannides, K G; Johnson, E; Soucacos, P N

1999-05-19

Strontium-90 concentration was measured in human bones and teeth collected in Greece during the period 1992-1996. One hundred and five bone samples, mainly cancellous bone, and 108 samples, taken from a total of 896 individual teeth were processed. Samples were classified according to the age and sex of the donors. Samples were chemically pre-treated according to a specially devised method to enable extraction of 90Y, at equilibrium with 90Sr in the original sample. Subsequently, 90Y beta activity was measured with a gas proportional counter. Radiostrontium concentration in bone samples showed small variations with respect to age or sex, with an average value of 30 mBq 90Sr/g Ca. However, 90Sr concentration measurements in teeth demonstrated a pronounced structure, which clearly reflects contamination from the 1960s atmospheric nuclear weapons tests and the more recent Chernobyl accident. This difference is attributed to the different histological structure of skeletal bones and teeth, the later consisting mainly of compact bone. An age-dependent model for radiostrontium concentration in human bones and teeth is developed which is able to successfully reproduce the experimental data. Through a fitting process, the model also yielded calcium turnover rates for compact bone, as a function of age, as well as an estimate of radiostrontium contamination of foodstuffs in Greece for the past four decades. The results obtained in this study indicate that radiostrontium environmental contamination which resulted from the atmospheric nuclear weapons tests in the 1960s, exceed by far that caused by the Chernobyl accident.

Cell interactions in bone tissue engineering.

PubMed

Pirraco, R P; Marques, A P; Reis, R L

2010-01-01

Bone fractures, where the innate regenerative bone response is compromised, represent between 4 and 8 hundred thousands of the total fracture cases, just in the United States. Bone tissue engineering (TE) brought the notion that, in cases such as those, it was preferable to boost the healing process of bone tissue instead of just adding artificial parts that could never properly replace the native tissue. However, despite the hype, bone TE so far could not live up to its promises and new bottom-up approaches are needed. The study of the cellular interactions between the cells relevant for bone biology can be of essential importance to that. In living bone, cells are in a context where communication with adjacent cells is almost permanent. Many fundamental works have been addressing these communications nonetheless, in a bone TE approach, the 3D perspective, being part of the microenvironment of a bone cell, is as crucial. Works combining the study of cell-to-cell interactions in a 3D environment are not as many as expected. Therefore, the bone TE field should not only gain knowledge from the field of fundamental Biology but also contribute for further understanding the biology of bone. In this review, a summary of the main works in the field of bone TE, aiming at studying cellular interactions in a 3D environment, and how they contributed towards the development of a functional engineered bone tissue, is presented.

Propionibacterium acnes infected intervertebral discs cause vertebral bone marrow lesions consistent with Modic changes.

PubMed

Dudli, Stefan; Liebenberg, Ellen; Magnitsky, Sergey; Miller, Steve; Demir-Deviren, Sibel; Lotz, Jeffrey C

2016-08-01

Modic type I change (MC1) are vertebral bone marrow lesions adjacent to degenerated discs that are specific for discogenic low back pain. The etiopathogenesis is unknown, but occult discitis, in particular with Propionibacteria acnes (P. acnes), has been suggested as a possible etiology. If true, antibiotic therapy should be considered for patients with MC1. However, this hypothesis is controversial. While some studies report up to 40% infection rate in herniated discs, others fail to detect infected discs and attribute reports of positive cultures to contamination during sampling procedure. Irrespective of the clinical controversy, whether it is biologically plausible for P. acnes to cause MC1 has never been investigated. Therefore, the objective of this study was to test if P. acnes can proliferate within discs and cause reactive changes in the adjacent bone marrow. P. acnes was aseptically isolated from a symptomatic human L4/5 disc with MC1 and injected into rat tail discs. We demonstrate proliferation of P. acnes and up-regulation of IL-1 and IL-6 within three days of inoculation. At day-7, disc degeneration was apparent along with fibrotic endplate erosion. TNF-α immunoreactivity was enhanced within the effected endplates along with cellular infiltrates. The bone marrow appeared normal. At day-14, endplates and trabecular bone close to the disc were almost completely resorbed and fibrotic tissue extended into the bone marrow. T-cells and TNF-α immunoreactivity were identified at the disc/marrow junction. On MRI, bone marrow showed MC1-like changes. In conclusion, P. acnes proliferate within the disc, induce degeneration, and cause MC1-like changes in the adjacent bone marrow. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1447-1455, 2016. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

Compact vacuum insulation

DOEpatents

Benson, David K.; Potter, Thomas F.

1992-01-01

Improved compact insulation panel is provided which is comprised of two adjacent metal sheets spaced close together with a plurality of spherical, or other discretely shaped, glass or ceramic beads optimally positioned between the sheets to provide support and maintain the spacing between the metal sheets when the gases therebetween are evacuated to form a vacuum. These spherical glass beads provide the maximum support while minimizing thermal conductance. In its preferred embodiment; these two metal sheets are textured with ribs or concave protrusions in conjunction with the glass beads to maximize the structural integrity of the panels while increasing the spacing between beads, thereby reducing the number of beads and the number of thermal conduction paths. Glass or porcelain-enameled liners in combination with the glass spacers and metal sidewalls effectively decrease thermal conductivity, and variious laminates, including wood, porcelain-enameled metal, and others effectively increase the strength and insulation capabilities of the panels. Also, a metal web is provided to hold the spacers in place, and strategic grooves are shown to accommodate expansion and contraction or shaping of the panels.

Documentation of a computer program to simulate aquifer-system compaction using the modular finite-difference ground-water flow model

USGS Publications Warehouse

Leake, S.A.; Prudic, David E.

1991-01-01

Removal of ground water by pumping from aquifers may result in compaction of compressible fine-grained beds that are within or adjacent to the aquifers. Compaction of the sediments and resulting land subsidence may be permanent if the head declines result in vertical stresses beyond the previous maximum stress. The process of permanent compaction is not routinely included in simulations of ground-water flow. To simulate storage changes from both elastic and inelastic compaction, a computer program was written for use with the U.S. Geological Survey modular finite-difference ground- water flow model. The new program, the Interbed-Storage Package, is designed to be incorporated into this model. In the Interbed-Storage Package, elastic compaction or expansion is assumed to be proportional to change in head. The constant of proportionality is the product of the skeletal component of elastic specific storage and the thickness of the sediments. Similarly, inelastic compaction is assumed to be proportional to decline in head. The constant of proportionality is the product of the skeletal component of inelastic specific storage and the thickness of the sediments. Storage changes are incorporated into the ground-water flow model by adding an additional term to the right-hand side of the flow equation. Within a model time step, the package appropriately apportions storage changes between elastic and inelastic components on the basis of the relation of simulated head to the previous minimum (preconsolidation) head. Two tests were performed to verify that the package works correctly. The first test compared model-calculated storage and compaction changes to hand-calculated values for a three-dimensional simulation. Model and hand-calculated values were essentially equal. The second test was performed to compare the results of the Interbed-Storage Package with results of the one-dimensional Helm compaction model. This test problem simulated compaction in doubly draining

Analysis of laboratory compaction methods of roller compacted concrete

NASA Astrophysics Data System (ADS)

Trtík, Tomáš; Chylík, Roman; Bílý, Petr; Fládr, Josef

2017-09-01

Roller-Compacted Concrete (RCC) is an ordinary concrete poured and compacted with machines typically used for laying of asphalt road layers. One of the problems connected with this technology is preparation of representative samples in the laboratory. The aim of this work was to analyse two methods of preparation of RCC laboratory samples with bulk density as the comparative parameter. The first method used dynamic compaction by pneumatic hammer. The second method of compaction had a static character. The specimens were loaded by precisely defined force in laboratory loading machine to create the same conditions as during static rolling (in the Czech Republic, only static rolling is commonly used). Bulk densities obtained by the two compaction methods were compared with core drills extracted from real RCC structure. The results have shown that the samples produced by pneumatic hammer tend to overestimate the bulk density of the material. For both compaction methods, immediate bearing index test was performed to verify the quality of compaction. A fundamental difference between static and dynamic compaction was identified. In static compaction, initial resistance to penetration of the mandrel was higher, after exceeding certain limit the resistance was constant. This means that the samples were well compacted just on the surface. Specimens made by pneumatic hammer actively resisted throughout the test, the whole volume was uniformly compacted.

Trace and macro elements in the femoral bone as indicators of long-term environmental exposure to toxic metals in European brown bear (Ursus arctos) from Croatia.

PubMed

Lazarus, Maja; Orct, Tatjana; Reljić, Slaven; Sedak, Marija; Bilandžić, Nina; Jurasović, Jasna; Huber, Đuro

2018-05-21

We explored the long-term accumulation of aluminium, strontium, cadmium and lead in the compact and trabecular bone of the femoral epiphysis, metaphysis and diaphysis in 41 brown bears (Ursus arctos) from Croatia. Also, we assessed their influence on macro and trace elements (sodium, magnesium, phosphorus, potassium, calcium, manganese, iron, cobalt, copper, zinc and barium) in bears' bone. There were no sex differences in element levels in general, while age was associated with bone length and levels of all elements, except for cadmium. Elements had different levels depending on the part of the bone sampled. More pronounced differences were observed between the compact and trabecular regions, with higher levels of majority of elements found in compact bone. Moderate to high associations (Spearman coefficient, r S  = 0.59-0.97) were confirmed between calcium and potassium, magnesium, phosphorus, manganese, cobalt, zinc, strontium and lead. Lead levels in the bone were below those known to cause adverse health effects, but in 4 of 41 animals they exceeded baseline levels for domestic animals. The femoral bone of the brown bear reflected the accumulative nature of lead and strontium well, as it did the impairment of bone-forming essential element levels associated with these two elements. However, the distribution pattern of elements along the bone was not uniform, so additional care should be taken when choosing on the part of the bone sampled.

Elastic intramedullary nailing and DBM-Bone marrow injection for the treatment of simple bone cysts

PubMed Central

Kanellopoulos, Anastasios D; Mavrogenis, Andreas F; Papagelopoulos, Panayiotis J; Soucacos, Panayotis N

2007-01-01

Background Simple or unicameral bone cysts are common benign fluid-filled lesions usually located at the long bones of children before skeletal maturity. Methods We performed demineralized bone matrix and iliac crest bone marrow injection combined with elastic intramedullary nailing for the treatment of simple bone cysts in long bones of 9 children with a mean age of 12.6 years (range, 4 to 15 years). Results Two of the 9 patients presented with a pathological fracture. Three patients had been referred after the failure of previous treatments. Four patients had large lesions with impending pathological fractures that interfered with daily living activities. We employed a ratio to ascertain the severity of the lesion. The extent of the lesion on the longitudinal axis was divided with the normal expected diameter of the long bone at the site of the lesion. The mean follow-up was 77 months (range, 5 to 8 years). All patients were pain free and had full range of motion of the adjacent joints at 6 weeks postoperatively. Review radiographs showed that all 7 cysts had consolidated completely (Neer stage I) and 2 cysts had consolidated partially (Neer stage II). Until the latest examination there was no evidence of fracture or re-fracture. Conclusion Elastic intramedullary nailing has the twofold benefits of continuous cyst decompression, and early immediate stability to the involved bone segment, which permits early mobilization and return to the normal activities of the pre-teen patients. PMID:17916249

Electron Microscopy and Analytical X-ray Characterization of Compositional and Nanoscale Structural Changes in Fossil Bone

NASA Astrophysics Data System (ADS)

Boatman, Elizabeth Marie

The nanoscale structure of compact bone contains several features that are direct indicators of bulk tissue mechanical properties. Fossil bone tissues represent unique opportunities to understand the compact bone structure/property relationships from a deep time perspective, offering a possible array of new insights into bone diseases, biomimicry of composite materials, and basic knowledge of bioapatite composition and nanoscale bone structure. To date, most work with fossil bone has employed microscale techniques and has counter-indicated the survival of bioapatite and other nanoscale structural features. The obvious disconnect between the use of microscale techniques and the discernment of nanoscale structure has prompted this work. The goal of this study was to characterize the nanoscale constituents of fossil compact bone by applying a suite of diffraction, microscopy, and spectrometry techniques, representing the highest levels of spatial and energy resolution available today, and capable of complementary structural and compositional characterization from the micro- to the nanoscale. Fossil dinosaur and crocodile long bone specimens, as well as modern ratite and crocodile femurs, were acquired from the UC Museum of Paleontology. Preserved physiological features of significance were documented with scanning electron microscopy back-scattered imaging. Electron microprobe wavelength-dispersive X-ray spectroscopy (WDS) revealed fossil bone compositions enriched in fluorine with a complementary loss of oxygen. X-ray diffraction analyses demonstrated that all specimens were composed of apatite. Transmission electron microscopy (TEM) imaging revealed preserved nanocrystallinity in the fossil bones and electron diffraction studies further identified these nanocrystallites as apatite. Tomographic analyses of nanoscale elements imaged by TEM and small angle X-ray scattering were performed, with the results of each analysis further indicating that nanoscale structure is

Titanium compacts produced by the pulvimetallurgical hydride-dehydride method for biomedical applications.

PubMed

Barreiro, M M; Grana, D R; Kokubu, G A; Luppo, M I; Mintzer, S; Vigna, G

2010-04-01

Titanium powder production by the hydride-dehydride method has been developed as a non-expensive process. In this work, commercially pure grade two Ti specimens were hydrogenated. The hydrided material was milled in a planetary mill. The hydrided titanium powder was dehydrided and then sieved to obtain a particle size between 37 and 125 microm in order to compare it with a commercial powder produced by chemical reduction with a particle size lower than 150 microm. Cylindrical green compacts were obtained by uniaxial pressing of the powders at 343 MPa and sintering in vacuum. The powders and the density of sintered compacts were characterized, the oxygen content was measured and in vivo tests were performed in the tibia bones of Wistar rats in order to evaluate their biocompatibility. No differences were observed between the materials which were produced either with powders obtained by the hydride-dehydride method or with commercial powders produced by chemical reduction regarding modifications in compactation, sintering and biological behaviour.

Bone formation at recombinant human bone morphogenetic protein-2-coated titanium implants in the posterior mandible (Type II bone) in dogs.

PubMed

Wikesjö, Ulf M E; Xiropaidis, Andreas V; Qahash, Mohammed; Lim, Won Hee; Sorensen, Rachel G; Rohrer, Michael D; Wozney, John M; Hall, Jan

2008-11-01

Conventional oral/maxillofacial implants reach osseointegration over several months during which the titanium fixtures interact with alveolar bone. The objective of this study was to determine if adsorbing recombinant human bone morphogenetic protein-2 (rhBMP-2) onto a titanium porous oxide (TPO) implant surface might enhance or accelerate local bone formation and support osseointegration in a large animal oral/maxillofacial orthotopic model. Endosseous implants with a TPO surface were installed into the edentulated posterior mandible in eight adult Hound Labrador mongrel dogs. The implant surface had been adsorbed with rhBMP-2 at 0.2 or 4.0 mg/ml. TPO implants without rhBMP-2 served as control. Treatments were randomized between jaw quadrants. Mucosal flaps were advanced and sutured leaving the implants submerged. Clinical and radiographic evaluations were made immediately post-surgery, at day 10 (suture removal), and week 4 and 8 post-surgery. The animals received fluorescent bone markers at week 3, 4, and at week 8 post-surgery, when they were euthanized for histologic analysis. TPO implants coated with rhBMP-2 exhibited dose-dependent bone remodelling including immediate resorption and formation of implant adjacent bone, and early establishment of clinically relevant osseointegration. The resulting bone-implant contact, although clinically respectable, appeared significantly lower for rhBMP-2-coated implants compared with the control [rhBMP-2 (0.2 mg/ml) 43.3+/-10.8%versus 71.7+/-7.8%, p<0.02; rhBMP-2 (4.0 mg/ml) 35.4+/-10.6%versus 68.2+/-11.0%, p<0.03]. rhBMP-2 adsorbed onto TPO implant surfaces initiates dose-dependent peri-implant bone re-modelling resulting in the formation of normal, physiologic bone and clinically relevant osseointegration within 8 weeks.

Femoroacetabular impingement: bone marrow oedema associated with fibrocystic change of the femoral head and neck junction.

PubMed

James, S L J; Connell, D A; O'Donnell, P; Saifuddin, A

2007-05-01

To describe the association of bone marrow oedema adjacent to areas of fibrocystic change at the femoral head and neck junction in patients with femoroacetabular impingement. The clinical and imaging findings in six patients with bone marrow oedema adjacent to an area of fibrocystic change at the femoral head and neck junction are presented. There were five males and one female (age range 19-42 years, mean age 34.5 years). Three patients were referred with a clinical suspicion of femoroacetabular impingement, two with suspected osteoid osteoma and one with a clinical diagnosis of sciatica. The volume of bone marrow oedema (grade 1: 0-25%, grade 2: 26-50%, grade 3: 51-75% and grade 4: 76-100% of the femoral neck width), presence of labral and articular cartilage abnormality, joint effusion, and femoral head and neck morphology were recorded. Magnetic resonance imaging (MRI) identified fibrocystic change in the anterolateral aspect of the femoral head and neck junction in all cases (mean size 9 mm, range 5-14 mm, three multilocular and three unilocular cysts). The volume of oedema was variable (one grade 1, two grade 2, one grade 3 and two grade 4). All patients had abnormality of the anterosuperior labrum with five patients demonstrating chondral loss. An abnormal femoral head and neck junction was identified in five patients. The radiological finding of fibrocystic change at the anterosuperior femoral neck with or without bone marrow oedema should prompt the search for femoroacetabular impingement. Bone marrow oedema may rarely be identified adjacent to these areas of cystic change and should be considered in the differential diagnosis of bone marrow oedema in the femoral neck.

[Stereological analysis of rat bone tissue after a flight on the Kosmos-1129 biosatellite].

PubMed

Prokhonchukov, A A; Peschanskiĭ, V S

1982-01-01

Stereological measurements of volume fractions of 53 samples of compact and spongy structures of bones of 15 rats were carried out. The measurements were performed on cortical lamellae, trabecules and lacunae, channels of osteons and matrices of femoral, tibial and fibular bones of rats. Postflight no significant changes were seen in the above parameters as compared to the vivarium controls. During readaptation to I g a slight increase in the volume fraction of spongy bones was noted.

Hidden secrets of deformation: Impact-induced compaction within a CV chondrite

NASA Astrophysics Data System (ADS)

Forman, L. V.; Bland, P. A.; Timms, N. E.; Collins, G. S.; Davison, T. M.; Ciesla, F. J.; Benedix, G. K.; Daly, L.; Trimby, P. W.; Yang, L.; Ringer, S. P.

2016-10-01

The CV3 Allende is one of the most extensively studied meteorites in worldwide collections. It is currently classified as S1-essentially unshocked-using the classification scheme of Stöffler et al. (1991), however recent modelling suggests the low porosity observed in Allende indicates the body should have undergone compaction-related deformation. In this study, we detail previously undetected evidence of impact through use of Electron Backscatter Diffraction mapping to identify deformation microstructures in chondrules, AOAs and matrix grains. Our results demonstrate that forsterite-rich chondrules commonly preserve crystal-plastic microstructures (particularly at their margins); that low-angle boundaries in deformed matrix grains of olivine have a preferred orientation; and that disparities in deformation occur between chondrules, surrounding and non-adjacent matrix grains. We find heterogeneous compaction effects present throughout the matrix, consistent with a highly porous initial material. Given the spatial distribution of these crystal-plastic deformation microstructures, we suggest that this is evidence that Allende has undergone impact-induced compaction from an initially heterogeneous and porous parent body. We suggest that current shock classifications (Stöffler et al., 1991) relying upon data from chondrule interiors do not constrain the complete shock history of a sample.

Differentiating zones at periodontal ligament-bone and periodontal ligament-cementum entheses.

PubMed

Lee, J-H; Pryce, B A; Schweitzer, R; Ryder, M I; Ho, S P

2015-12-01

The structural and functional integrity of bone-periodontal ligament (PDL)-cementum complex stems from the load-bearing attachment sites (entheses) between soft (PDL) and hard (bone, cementum) tissues. These attachment sites are responsible for the maintenance of a bone-PDL-cementum complex biomechanical function. The objective was to investigate changes in spatiotemporal expression of key biomolecules in developing and functionally active entheses. Multilabeling technique was performed on hemimandibles of 3 wk and 3 mo-old scleraxis-GFP transgenic mice for CD146, CD31, NG2, osterix and bone sialoprotein. Regions of dominant stretch within the PDL were evaluated by identifying directionality of collagen fibrils, PDL fibroblasts and PDL cell cytoskeleton. CD146+ cells adjacent to CD31+ vasculature were identified at PDL-bone enthesis. NG2+ cells were located at coronal bone-PDL and apical cementum-PDL entheses in the 3-wk-old group, but at 3 mo, NG2 was positive at the entheses of the apical region and alveolar crest. NG2 and osterix were colocalized at the osteoid and cementoid regions of the PDL-bone and PDL-cementum entheses. Bone sialoprotein was prominent at the apical region of 3-wk-old mice. The directionality of collagen fibers, fibroblasts and their cytoskeleton overlapped, except in the apical region of 3 wk. Colocalization of biomolecules at zones of the PDL adjacent to attachment sites may be essential for the formation of precementum and osteoid interfaces at a load-bearing bone-PDL-tooth fibrous joint. Biophysical cues resulting from development and function can regulate recruitment and differentiation of stem cells potentially from a vascular origin toward osteo- and cemento-blastic lineages at the PDL-bone and PDL-cementum entheses. Investigating the coupled effect of biophysical and biochemical stimuli leading to cell differentiation at the functional attachment sites is critical for developing regeneration strategies to enable functional

Compact vacuum insulation

DOEpatents

Benson, D.K.; Potter, T.F.

1992-10-27

Improved compact insulation panel is provided which is comprised of two adjacent metal sheets spaced close together with a plurality of spherical, or other discretely shaped, glass or ceramic beads optimally positioned between the sheets to provide support and maintain the spacing between the metal sheets when the gases there between are evacuated to form a vacuum. These spherical glass beads provide the maximum support while minimizing thermal conductance. In its preferred embodiment; these two metal sheets are textured with ribs or concave protrusions in conjunction with the glass beads to maximize the structural integrity of the panels while increasing the spacing between beads, thereby reducing the number of beads and the number of thermal conduction paths. Glass or porcelain-enameled liners in combination with the glass spacers and metal sidewalls effectively decrease thermal conductivity, and various laminates, including wood, porcelain-enameled metal, and others effectively increase the strength and insulation capabilities of the panels. Also, a metal web is provided to hold the spacers in place, and strategic grooves are shown to accommodate expansion and contraction or shaping of the panels. 35 figs.

Percutaneous magnetic resonance imaging-guided bone tumor management and magnetic resonance imaging-guided bone therapy.

PubMed

Sequeiros, Roberto Blanco; Fritz, Jan; Ojala, Risto; Carrino, John A

2011-08-01

Magnetic resonance imaging (MRI) is promising tool for image-guided therapy. In musculoskeletal setting, image-guided therapy is used to direct diagnostic and therapeutic procedures and to steer patient management. Studies have demonstrated that MRI-guided interventions involving bone, soft tissue, joints, and intervertebral disks are safe and in selected indications can be the preferred action to manage clinical situation. Often, these procedures are technically similar to those performed in other modalities (computed tomography, fluoroscopy) for bone and soft tissue lesions. However, the procedural perception to the operator can be very different to other modalities because of the vastly increased data.Magnetic resonance imaging guidance is particularly advantageous should the lesion not be visible by other modalities, for selective lesion targeting, intra-articular locations, cyst aspiration, and locations adjacent to surgical hardware. Palliative tumor-related pain management such as ablation therapy forms a subset of procedures that are frequently performed under MRI. Another suitable entity for MRI guidance are the therapeutic percutaneous osseous or joint-related benign or reactive conditions such as osteoid osteoma, epiphyseal bone bridging, osteochondritis dissecans, bone cysts, localized bone necrosis, and posttraumatic lesions. In this article, we will describe in detail the technical aspects of performing MRI-guided therapeutic musculoskeletal procedures as well as the clinical indications.

Water-level altitudes 2015 and water-level changes in the Chicot, Evangeline, and Jasper aquifers and compaction 1973-2014 in the Chicot and Evangeline aquifers, Houston-Galveston region, Texas

USGS Publications Warehouse

Kasmarek, Mark C.; Ramage, Jason K.; Houston, Natalie A.; Johnson, Michaela R.; Schmidt, Tiffany S.

2015-01-01

Compaction of subsurface sediments (mostly in the fine-grained silt and clay layers) composing the Chicot and Evangeline aquifers was recorded continuously by using analog technology at the 13 borehole extensometers at 11 sites that were either activated or installed between 1973 and 1980. For the period of record beginning in 1973 (or later depending on activation or installation date) and ending in December 2014, measured cumulative compaction at the 13 extensometers ranged from 0.101 ft at the Texas City-Moses Lake extensometer to 3.668 ft at the Addicks extensometer. During 2014, a total of 10 of the 13 extensometers recorded a slight net decrease of land-surface elevation; the extensometers at the Lake Houston and Clear Lake (shallow) sites recorded slight net increases of land-surface elevation, and the extensometer at the Texas City-Moses Lake site recorded no change in elevation. The rate of compaction varies from site to site because of differences in rates of groundwater withdrawal in the areas adjacent to each extensometer site and differences among sites in the ratios of sand, silt, and clay and compressibilities of the subsurface sediments. It is not appropriate, therefore, to extrapolate or infer a rate of compaction for an adjacent area on the basis of the rate of compaction measured at nearby extensometers.

Customized compact neutron activation analysis system to quantify manganese (Mn) in bone in vivo

PubMed Central

Liu, Yingzi; Mostafaei, Farshad; Sowers, Daniel; Hsieh, Mindy; Zheng, Wei; Nie, Linda H

2018-01-01

Objective In the US alone, millions of workers, including over 300 000 welders, are at high risk of occupational manganese (Mn) exposure. Those who have been chronically exposed to excessive amount of Mn can develop severe neurological disorders similar, but not identical, to the idiopathic Parkinson’s disease. One challenge of identifing the health effects of Mn exposure is to find a reliable biomarker for exposure assessment, especially for long-term cumulative exposure. Approach Mn’s long biological half-life as well as its relatively high concentration in bone makes bone Mn (BnMn) a potentially valuable biomarker for Mn exposure. Our group has been working on the development of a deuterium–deuterium (D–D)-based neutron generator to quantify Mn in bone in vivo. Main results and significance In this paper, we report the latest advancements in our system. With a customized hand irradiation assembly, a fully characterized high purity germanium (HPGe) detector system, and an acceptable hand dose of 36 mSv, a detection limit of 0.64 µg Mn/g bone (ppm) has been achieved. PMID:28060775

Measuring the stopping power of α particles in compact bone for BNCT

NASA Astrophysics Data System (ADS)

Provenzano, L.; Rodríguez, L. M.; Fregenal, D.; Bernardi, G.; Olivares, C.; Altieri, S.; Bortolussi, S.; González, S. J.

2015-01-01

The stopping power of α particles in thin films of decalcified sheep femur, in the range of 1.5 to 5.0 MeV incident energy, was measured by transmission of a backscattered beam from a heavy target. Additionally, the film elemental composition was determined by Rutherford Backscattering Spectrometry (RBS). These data will be used to measure boron concentration in thin films of bone using a spectrometry technique developed by the University of Pavia, since the concentration ratio between healthy tissue and tumor is of fundamental importance in Boron Neutron Capture Therapy (BNCT). The present experimental data are compared with numerical simulation results and with tabulated stopping power data of non-decalcified human bone.

A procedure for preparing undecalcified and unembedded bone sections for light microscopy.

PubMed

Mancini, M; Spoliti, M; Botti, F; Ragazzoni, E; Cocchia, D

1997-07-01

We have developed a procedure for light microscopic investigation of undecalcified and unembedded bone sections. Biopsy samples of human metatarsus and femur and rat femur were fixed in aldehydes and sectioned with a cutting machine equipped with a diamond saw blade. Free sections 100-150 microns thick, stained with toluidine blue and von Kossa, did not show artifacts following the cutting, and the spatial relations of mineralized and nonmineralized components remained intact. Compact and trabecular bone, bone marrow and all cell types appeared well preserved and easily recognizable. Our procedure provides a simple and rapid method for preparing bone sections which undergo no chemical treatment other than fixation. This method is a useful alternative to standard histological protocols for studying bone specimens.

Size cues and the adjacency principle.

DOT National Transportation Integrated Search

1963-11-01

The purpose of the present study was to apply the adjacency principle to the perception of relative depth from size cues. In agreement with the adjacency principle, it was found that the size cue between adjacent objects was more effective than the s...

Use of piezoelectric bone scalpel in hand and reconstructive microsurgery.

PubMed

Arnez, Z; Papa, G; Renzi, N; Ramella, V; Panizzo, N; Toffanetti, F

2009-01-01

Performing osteotomies with piezoelectric bone scalpel is also possible with bones of larger diameter/thickness. At the same time, adjacent soft tissues are not in danger from cutting or thermal damage, reducing the risk of damaging neurovascular structures - which is of primary importance in hand and reconstructive microsurgery. These features contribute to the safety and easy execution of the procedure. The resulting bony cut is precise and permits immediate and safe bone fixation. Osteotomy of bones of >1 cm thickness takes 20-30% longer than when using a conventional oscillating saw, though the increased safety of the procedure more than compensates for this. Three cases are presented, illustrating of the use of Genera Ultrasonic for cutting bones of major thickness (metacarpal, fibula and rib) without any complication. Because of its selectivity for bony tissue, precision and ability to protect soft tissues we also advocate the use of the Genera piezoelectric bone scalpel in hand and reconstructive microsurgery.

Effects of fibrinogen concentration on fibrin glue and bone powder scaffolds in bone regeneration.

PubMed

Kim, Beom-Su; Sung, Hark-Mo; You, Hyung-Keun; Lee, Jun

2014-10-01

Fibrin polymers are widely used in the tissue engineering field as biomaterials. Although numerous researchers have studied the fabrication of scaffolds using fibrin glue (FG) and bone powder, the effects of varied fibrinogen content during the fabrication of scaffolds on human mesenchymal stem cells (hMSCs) and bone regeneration remain poorly understood. In this study, we formulated scaffolds using demineralized bone powder and various fibrinogen concentrations and analyzed the microstructure and mechanical properties. Cell proliferation, cell viability, and osteoblast differentiation assays were performed. The ability of the scaffold to enhance bone regeneration was evaluated using a rabbit calvarial defect model. Micro-computed tomography (micro-CT) showed that bone powders were uniformly distributed on the scaffolds, and scanning electron microscopy (SEM) showed that the fibrin networks and flattened fibrin layers connected adjacent bone powder particles. When an 80 mg/mL fibrinogen solution was used to formulate scaffolds, the porosity decreased 41.6 ± 3.6%, while the compressive strength increased 1.16 ± 0.02 Mpa, when compared with the values for the 10 mg/mL fibrinogen solution. Proliferation assays and SEM showed that the scaffolds prepared using higher fibrinogen concentrations supported and enhanced cell adhesion and proliferation. In addition, mRNA expression of alkaline phosphatase and osteocalcin in cells grown on the scaffolds increased with increasing fibrinogen concentration. Micro-CT and histological analysis revealed that newly formed bone was stimulated in the scaffold implantation group. Our results demonstrate that optimization of the fibrinogen content of fibrin glue/bone powder scaffolds will be beneficial for bone tissue engineering. Copyright © 2014 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

The behaviour of fatigue-induced microdamage in compact bone samples from control and ovariectomised sheep.

PubMed

Kennedy, Oran D; Brennan, Orlaith; Mauer, Peter; O'Brien, Fergal J; Rackard, Susan M; Taylor, David; Lee, T Clive

2008-01-01

This study investigates the effect of microdamage on bone quality in osteoporosis using an ovariectomised (OVX) sheep model of osteoporosis. Thirty-four sheep were divided into an OVX group (n=16) and a control group (n=18). Fluorochromes were administered intravenously at 3 monthly intervals after surgery to label bone turnover. After sacrifice, beams were removed from the metatarsal and tested in three-point bending. Following failure, microcracks were identified and quantified in terms of region, location and interaction with osteons. Number of cycles to failure (Nf) was lower in the OVX group relative to controls by approximately 7%. Crack density (CrDn) was higher in the OVX group compared to controls. CrDn was 2.5 and 3.5 times greater in the compressive region compared to tensile in control and OVX bone respectively. Combined results from both groups showed that 91% of cracks remained in interstitial bone, approximately 8% of cracks penetrated unlabelled osteons and less than 1% penetrated into labelled osteons. All cases of labelled osteon penetration occurred in controls. Crack surface density (CrSDn), was 25% higher in the control group compared to OVX. It is known that crack behaviour on meeting microstructural features such as osteons will depend on crack length. We have shown that osteon age also affects crack propagation. Long cracks penetrated unlabelled osteons but not labelled ones. Some cracks in the control group did penetrate labelled osteons. This may be due the fact that control bone is more highly mineralized. CrSDn was increased by 25% in the control group compared to OVX. Further study of these fracture mechanisms will help determine the effect of microdamage on bone quality and how this contributes to bone fragility.

Methods and theory in bone modeling drift: comparing spatial analyses of primary bone distributions in the human humerus.

PubMed

Maggiano, Corey M; Maggiano, Isabel S; Tiesler, Vera G; Chi-Keb, Julio R; Stout, Sam D

2016-01-01

This study compares two novel methods quantifying bone shaft tissue distributions, and relates observations on human humeral growth patterns for applications in anthropological and anatomical research. Microstructural variation in compact bone occurs due to developmental and mechanically adaptive circumstances that are 'recorded' by forming bone and are important for interpretations of growth, health, physical activity, adaptation, and identity in the past and present. Those interpretations hinge on a detailed understanding of the modeling process by which bones achieve their diametric shape, diaphyseal curvature, and general position relative to other elements. Bone modeling is a complex aspect of growth, potentially causing the shaft to drift transversely through formation and resorption on opposing cortices. Unfortunately, the specifics of modeling drift are largely unknown for most skeletal elements. Moreover, bone modeling has seen little quantitative methodological development compared with secondary bone processes, such as intracortical remodeling. The techniques proposed here, starburst point-count and 45° cross-polarization hand-drawn histomorphometry, permit the statistical and populational analysis of human primary tissue distributions and provide similar results despite being suitable for different applications. This analysis of a pooled archaeological and modern skeletal sample confirms the importance of extreme asymmetry in bone modeling as a major determinant of microstructural variation in diaphyses. Specifically, humeral drift is posteromedial in the human humerus, accompanied by a significant rotational trend. In general, results encourage the usage of endocortical primary bone distributions as an indicator and summary of bone modeling drift, enabling quantitative analysis by direction and proportion in other elements and populations. © 2015 Anatomical Society.

46 CFR 148.445 - Adjacent spaces.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 5 2011-10-01 2011-10-01 false Adjacent spaces. 148.445 Section 148.445 Shipping COAST... THAT REQUIRE SPECIAL HANDLING Additional Special Requirements § 148.445 Adjacent spaces. When... following requirements must be met: (a) Each space adjacent to a cargo hold must be ventilated by natural...

46 CFR 148.445 - Adjacent spaces.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 5 2014-10-01 2014-10-01 false Adjacent spaces. 148.445 Section 148.445 Shipping COAST... THAT REQUIRE SPECIAL HANDLING Additional Special Requirements § 148.445 Adjacent spaces. When... following requirements must be met: (a) Each space adjacent to a cargo hold must be ventilated by natural...

46 CFR 148.445 - Adjacent spaces.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 5 2013-10-01 2013-10-01 false Adjacent spaces. 148.445 Section 148.445 Shipping COAST... THAT REQUIRE SPECIAL HANDLING Additional Special Requirements § 148.445 Adjacent spaces. When... following requirements must be met: (a) Each space adjacent to a cargo hold must be ventilated by natural...

46 CFR 148.445 - Adjacent spaces.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 5 2012-10-01 2012-10-01 false Adjacent spaces. 148.445 Section 148.445 Shipping COAST... THAT REQUIRE SPECIAL HANDLING Additional Special Requirements § 148.445 Adjacent spaces. When... following requirements must be met: (a) Each space adjacent to a cargo hold must be ventilated by natural...

Water-level altitudes 2012 and water-level changes in the Chicot, Evangeline, and Jasper aquifers and compaction 1973-2011 in the Chicot and Evangeline aquifers, Houston-Galveston region, Texas

USGS Publications Warehouse

Kasmarek, Mark C.; Johnson, Michaela R.; Ramage, Jason K.

2012-01-01

Compaction of subsurface sediments (mostly in the clay layers) composing the Chicot and Evangeline aquifers was recorded continuously at 13 borehole extensometers at 11 sites. For the period of record beginning in 1973 (or later) and ending in December 2011, cumulative compaction data collected from the 13 extensometers ranged from 0.102 ft at the Texas City–Moses Lake site to 3.621 ft at the Addicks site. The rate of compaction varies from site to site because of differences in groundwater withdrawals near each site and differences among sites in the clay-to-sand ratio in the subsurface sediments. Therefore, it is not possible to extrapolate or infer a rate of compaction for adjacent areas on the basis of the rate of compaction measured at a nearby extensometer.

Insulin-like growth factor 1, glycation and bone fragility: implications for fracture resistance of bone.

PubMed

Sroga, Grażyna E; Wu, Ping-Cheng; Vashishth, Deepak

2015-01-01

Despite our extensive knowledge of insulin-like growth factor 1 (IGF1) action on the growing skeleton, its role in skeletal homeostasis during aging and age-related development of certain diseases is still unclear. Advanced glycation end products (AGEs) derived from glucose are implicated in osteoporosis and a number of diabetic complications. We hypothesized that because in humans and rodents IGF1 stimulates uptake of glucose (a glycation substrate) from the bloodstream in a dose-dependent manner, the decline of IGF1 could be associated with the accumulation of glycation products and the decreasing resistance of bone to fracture. To test the aforementioned hypotheses, we used human tibial posterior cortex bone samples to perform biochemical (measurement of IGF1, fluorescent AGEs and pentosidine (PEN) contents) and mechanical tests (crack initiation and propagation using compact tension specimens). Our results for the first time show a significant, age-independent association between the levels of IGF1 and AGEs. Furthermore, AGEs (fAGEs, PEN) predict propensity of bone to fracture (initiation and propagation) independently of age in human cortical bone. Based on these results we propose a model of IGF1-based regulation of bone fracture. Because IGF1 level increases postnatally up to the juvenile developmental phase and decreases thereafter with aging, we propose that IGF1 may play a protective role in young skeleton and its age-related decline leads to bone fragility and an increased fracture risk. Our results may also have important implications for current understanding of osteoporosis- and diabetes-related bone fragility as well as in the development of new diagnostic tools to screen for fragile bones.

Insulin-Like Growth Factor 1, Glycation and Bone Fragility: Implications for Fracture Resistance of Bone

PubMed Central

Sroga, Grażyna E.; Wu, Ping-Cheng; Vashishth, Deepak

2015-01-01

Despite our extensive knowledge of insulin-like growth factor 1 (IGF1) action on the growing skeleton, its role in skeletal homeostasis during aging and age-related development of certain diseases is still unclear. Advanced glycation end products (AGEs) derived from glucose are implicated in osteoporosis and a number of diabetic complications. We hypothesized that because in humans and rodents IGF1 stimulates uptake of glucose (a glycation substrate) from the bloodstream in a dose-dependent manner, the decline of IGF1 could be associated with the accumulation of glycation products and the decreasing resistance of bone to fracture. To test the aforementioned hypotheses, we used human tibial posterior cortex bone samples to perform biochemical (measurement of IGF1, fluorescent AGEs and pentosidine (PEN) contents) and mechanical tests (crack initiation and propagation using compact tension specimens). Our results for the first time show a significant, age-independent association between the levels of IGF1 and AGEs. Furthermore, AGEs (fAGEs, PEN) predict propensity of bone to fracture (initiation and propagation) independently of age in human cortical bone. Based on these results we propose a model of IGF1-based regulation of bone fracture. Because IGF1 level increases postnatally up to the juvenile developmental phase and decreases thereafter with aging, we propose that IGF1 may play a protective role in young skeleton and its age-related decline leads to bone fragility and an increased fracture risk. Our results may also have important implications for current understanding of osteoporosis- and diabetes-related bone fragility as well as in the development of new diagnostic tools to screen for fragile bones. PMID:25629402

Macrophages: Their Emerging Roles in Bone

PubMed Central

Sinder, Benjamin P; Pettit, Allison R; McCauley, Laurie K

2016-01-01

Macrophages are present in nearly all tissues and are critical for development, homeostasis, and regeneration. Resident tissue macrophages of bone, termed osteal macrophages, are recently classified myeloid cells that are distinct from osteoclasts. Osteal macrophages are located immediately adjacent to osteoblasts, regulate bone formation, and play diverse roles in skeletal homeostasis. Genetic or pharmacological modulation of macrophages in vivo results in significant bone phenotypes, and these phenotypes depend on which macrophage subsets are altered. Macrophages are also key mediators of osseous wound healing and fracture repair, with distinct roles at various stages of the repair process. A central function of macrophages is their phagocytic ability. Each day, billions of cells die in the body and efferocytosis (phagocytosis of apoptotic cells) is a critical process in both clearing dead cells and recruitment of replacement progenitor cells to maintain homeostasis. Recent data suggest a role for efferocytosis in bone biology and these new mechanisms are outlined. Finally, although macrophages have an established role in primary tumors, emerging evidence suggests that macrophages in bone support cancers which preferentially metastasize to the skeleton. Collectively, this developing area of osteoimmunology raises new questions and promises to provide novel insights into pathophysiologic conditions as well as therapeutic and regenerative approaches vital for skeletal health. PMID:26531055

Ewing's sarcoma of bone tumor cells produces MCSF that stimulates monocyte proliferation in a novel mouse model of Ewing's sarcoma of bone.

PubMed

Margulies, B S; DeBoyace, S D; Damron, T A; Allen, M J

2015-10-01

Ewing's sarcoma of bone is a primary childhood malignancy of bone that is treated with X-radiation therapy in combination with surgical excision and chemotherapy. To better study Ewing's sarcoma of bone we developed a novel model of primary Ewing's sarcoma of bone and then treated animals with X-radiation therapy. We identified that uncontrolled tumor resulted in lytic bone destruction while X-radiation therapy decreased lytic bone destruction and increased limb-length asymmetry, a common, crippling complication of X-radiation therapy. Osteoclasts were indentified adjacent to the tumor, however, we were unable to detect RANK-ligand in the Ewing's tumor cells in vitro, which lead us to investigate alternate mechanisms for osteoclast formation. Ewing's sarcoma tumor cells and archival Ewing's sarcoma of bone tumor biopsy samples were shown to express MCSF, which could promote osteoclast formation. Increased monocyte numbers were detected in peripheral blood and spleen in animals with untreated Ewing's sarcoma tumor while monocyte number in animals treated with x-radiation had normal numbers of monocytes. Our data suggest that our Ewing's sarcoma of bone model will be useful in the study Ewing's sarcoma tumor progression in parallel with the effects of chemotherapy and X-radiation therapy. Copyright © 2015 Elsevier Inc. All rights reserved.

Ewing's Sarcoma of Bone Tumor Cells Produce MCSF that Stimulates Monocyte Proliferation in a Novel Mouse Model of Ewing's Sarcoma of Bone

PubMed Central

Margulies, BS; DeBoyace, SD; Damron, TA; Allen, MJ

2015-01-01

Ewing's sarcoma of bone is a primary childhood malignancy of bone that is treated with X-radiation therapy in combination with surgical excision and chemotherapy. To better study Ewing's sarcoma of bone we developed a novel model of primary Ewing's sarcoma of bone and then treated animals with X-radiation therapy. We identified that uncontrolled tumor resulted in lytic bone destruction while X-radiation therapy decreased lytic bone destruction and increased limb-length asymmetry, a common, crippling complication of X-radiation therapy. Osteoclasts were indentified adjacent to the tumor, however, we were unable to detect RANK-ligand in the Ewing's tumor cells in vitro, which lead us to investigate alternate mechanisms for osteoclast formation. Ewing's sarcoma tumor cells and archival Ewing's sarcoma of bone tumor biopsy samples were shown to express MCSF, which could promote osteoclast formation. Increased monocyte numbers were detected in peripheral blood and spleen in animals with untreated Ewing's sarcoma tumor while monocyte number in animals treated with x-radiation had normal numbers of monocytes. Our data suggest that our Ewing's sarcoma of bone model will be useful in the study Ewing's sarcoma tumor progression in parallel with the effects of chemotherapy and X-radiation therapy. PMID:26051470

Mechanistic aspects of fracture and R-curve behavior in elk antler bone

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

Launey, Maximilien E.; Chen, Po-Yu; McKittrick, Joanna

Bone is an adaptative material that is designed for different functional requirements; indeed, bones have a variety of properties depending on their role in the body. To understand the mechanical response of bone requires the elucidation of its structure-function relationships. Here, we examine the fracture toughness of compact bone of elk antler which is an extremely fast growing primary bone designed for a totally different function than human (secondary) bone. We find that antler in the transverse (breaking) orientation is one of the toughest biological materials known. Its resistance to fracture is achieved during crack growth (extrinsically) by a combinationmore » of gross crack deflection/twisting and crack bridging via uncracked 'ligaments' in the crack wake, both mechanisms activated by microcracking primarily at lamellar boundaries. We present an assessment of the toughening mechanisms acting in antler as compared to human cortical bone, and identify an enhanced role of inelastic deformation in antler which further contributes to its (intrinsic) toughness.« less

Mouse Embryo Compaction.

PubMed

White, M D; Bissiere, S; Alvarez, Y D; Plachta, N

2016-01-01

Compaction is a critical first morphological event in the preimplantation development of the mammalian embryo. Characterized by the transformation of the embryo from a loose cluster of spherical cells into a tightly packed mass, compaction is a key step in the establishment of the first tissue-like structures of the embryo. Although early investigation of the mechanisms driving compaction implicated changes in cell-cell adhesion, recent work has identified essential roles for cortical tension and a compaction-specific class of filopodia. During the transition from 8 to 16 cells, as the embryo is compacting, it must also make fundamental decisions regarding cell position, polarity, and fate. Understanding how these and other processes are integrated with compaction requires further investigation. Emerging imaging-based techniques that enable quantitative analysis from the level of cell-cell interactions down to the level of individual regulatory molecules will provide a greater understanding of how compaction shapes the early mammalian embryo. © 2016 Elsevier Inc. All rights reserved.

Role of TGF-β in breast cancer bone metastases

PubMed Central

Chiechi, Antonella; Waning, David L.; Stayrook, Keith R.; Buijs, Jeroen T.; Guise, Theresa A.; Mohammad, Khalid S.

2014-01-01

Breast cancer is the most prevalent cancer among females worldwide leading to approximately 350,000 deaths each year. It has long been known that cancers preferentially metastasize to particular organs, and bone metastases occur in ~70% of patients with advanced breast cancer. Breast cancer bone metastases are predominantly osteolytic and accompanied by increased fracture risk, pain, nerve compression and hypercalcemia, causing severe morbidity. In the bone matrix, transforming growth factor-β (TGF-β) is one of the most abundant growth factors, which is released in active form upon tumor-induced osteoclastic bone resorption. TGF-β, in turn, stimulates bone metastatic tumor cells to secrete factors that further drive osteolytic bone destruction adjacent to the tumor. Thus, TGF-β is a crucial factor responsible for driving the feed-forward vicious cycle of cancer growth in bone. Moreover, TGF-β activates epithelial-to-mesenchymal transition, increases tumor cell invasiveness and angiogenesis and induces immunosuppression. Blocking the TGF-β signaling pathway to interrupt this vicious cycle between breast cancer and bone offers a promising target for therapeutic intervention to decrease skeletal metastasis. This review will describe the role of TGF-β in breast cancer and bone metastasis, and pre-clinical and clinical data will be evaluated for the potential use of TGF-β inhibitors in clinical practice to treat breast cancer bone metastases. PMID:24558636

Early changes in the distal intertarsal joint of Dutch Warmblood foals and the influence of exercise on bone density in the third tarsal bone.

PubMed

Barneveld, A; van Weeren, P R

1999-11-01

It was hypothesised that imposition of different exercise levels at a young age would lead to differences in bone density in the third tarsal bone and to difference in the prevalence of pathological lesions that might contribute to the development of bone spavin later in life. Furthermore, based on earlier literature, it was hypothesised that such lesions could be classified as a manifestation of osteochondrosis. Changes in bone density in the third tarsal bone and early pathological changes in the articular cartilage of the distal intertarsal joint were studied in the offspring of sires with radiographic evidence of osteochondrosis in either stifle or hock. Twenty-four foals were studied at age 5 months after having been subjected to different exercise programmes (box-rest, box-rest with sprint training, pasture exercise) from age one week. Nineteen other foals that originally belonged to the same exercise groups were studied at age 11 months, after they had been weaned, housed together and subjected to an identical low level exercise regimen for an additional 6 months. Bone density was quantified using a microscopic technique. Histomorphological analysis was performed semiquantitatively and using high detail radiography techniques. At age 5 months, mean +/- s.d. bone density in the compact bone of the third tarsal bone was significantly lower in the box-rested foals (37 +/- 4%) than in both the trained and pastured foals (48 +/- 7% and 52 +/- 11%, respectively). After 6 months of identical exercise the previously box-rested foals showed an increase in bone density (53 +/- 12%) which became similar to the value found in the formerly pastured foals (52 +/- 8%). Major pathological lesions (chondrocyte necrosis, fragmentation and chondrone formation) of the articular cartilage of the third and central tarsal bones were already present at age 5 months, but were significantly more numerous at 11 months. There was no relation between the number of cartilage lesions and

Bone matrix structure in different seasons of cervid antlerogenesis and gestation

NASA Astrophysics Data System (ADS)

Silvennoinen, Raimo V. J.; Nygren, Kaarlo; Rouvinen, Juha; Petrova, Valentina V.

1994-05-01

During the antlerogenesis and gestation, substantial amounts of mineral compounds are removed from the skeleton and transferred to the growing antler or foetus. We have used holographic nondestructive testing for sorting out biomechanically aberrant radioulnar bones of European moose and radiological methods to study, whether observed aberrations are due to changes of the structure of the long bones (radius). In males, these changes were studied in three phases of antler cycle: antlerless season, antler growing and mature antler. In females, the studies were made with samples of adult individuals in and after gestation period. We studied x-ray diffraction responses of the bones before and after compression up to saturation level. Our results are indicating that compact and spongy part of the bones are giving seasonally different biomechanical responses.

Anterior cement augmentation of adjacent levels after vertebral body replacement leads to superior stability of the corpectomy cage under cyclic loading-a biomechanical investigation.

PubMed

Oberkircher, Ludwig; Krüger, Antonio; Hörth, Dominik; Hack, Juliana; Ruchholtz, Steffen; Fleege, Christoph; Rauschmann, Michael; Arabmotlagh, Mohammad

2018-03-01

In the operative treatment of osteoporotic vertebral body fractures, a dorsal stabilization in combination with a corpectomy of the fractured vertebral body might be necessary with respect to the fracture morphology, whereby the osteoporotic bone quality may possibly increase the risk of implant failure. To achieve better stability, it is recommended to use cement-augmented screws for dorsal instrumentation. Besides careful end plate preparation, cement augmentation of the adjacent end plates has also been reported to lead to less reduction loss. The aim of the study was to evaluate biomechanically under cyclic loading whether an additional cement augmentation of the adjacent end plates leads to improved stability of the inserted cage. Methodical cadaver study. Fourteen fresh frozen human thoracic spines with proven osteoporosis were used (T2-T7). After removal of the soft tissues, the spine was embedded in Technovit (Kulzer, Germany). Subsequently, a corpectomy of T5 was performed, leaving the dorsal ligamentary structures intact. After randomization with respect to bone quality, two groups were generated: Dorsal instrumentation (cemented pedicle screws, Medtronic, Minneapolis, MN, USA)+cage implantation (CAPRI Corpectomy Cage, K2M, Leesburg, VA, USA) without additional cementation of the adjacent endplates (Group A) and dorsal instrumentation+cage implantation with additional cement augmentation of the adjacent end plates (Group B). The subsequent axial and cyclic loading was performed at a frequency of 1 Hz, starting at 400 N and increasing the load within 200 N after every 500 cycles up to a maximum of 2,200 N. Load failure was determined when the cages sintered macroscopically into the end plates (implant failure) or when the maximum load was reached. One specimen in Group B could not be clamped appropriately into the test bench for axial loading because of a pronounced scoliotic misalignment and had to be excluded. The mean strength for implant

Fractal-like hierarchical organization of bone begins at the nanoscale

NASA Astrophysics Data System (ADS)

Reznikov, Natalie; Bilton, Matthew; Lari, Leonardo; Stevens, Molly M.; Kröger, Roland

2018-05-01

The components of bone assemble hierarchically to provide stiffness and toughness. However, the organization and relationship between bone’s principal components—mineral and collagen—has not been clearly elucidated. Using three-dimensional electron tomography imaging and high-resolution two-dimensional electron microscopy, we demonstrate that bone mineral is hierarchically assembled beginning at the nanoscale: Needle-shaped mineral units merge laterally to form platelets, and these are further organized into stacks of roughly parallel platelets. These stacks coalesce into aggregates that exceed the lateral dimensions of the collagen fibrils and span adjacent fibrils as continuous, cross-fibrillar mineralization. On the basis of these observations, we present a structural model of hierarchy and continuity for the mineral phase, which contributes to the structural integrity of bone.

Temperature-dependent MR signals in cortical bone: potential for monitoring temperature changes during high-intensity focused ultrasound treatment in bone.

PubMed

Ramsay, Elizabeth; Mougenot, Charles; Kazem, Mohammad; Laetsch, Theodore W; Chopra, Rajiv

2015-10-01

Because existing magnetic resonance thermometry techniques do not provide temperature information within bone, high-intensity focused ultrasound (HIFU) exposures in bone are monitored using temperature changes in adjacent soft tissues. In this study, the potential to monitor temperature changes in cortical bone using a short TE gradient echo sequence is evaluated. The feasibility of this proposed method was initially evaluated by measuring the temperature dependence of the gradient echo signal during cooling of cortical bone samples implanted with fiber-optic temperature sensors. A subsequent experiment involved heating a cortical bone sample using a clinical MR-HIFU system. A consistent relationship between temperature change and the change in magnitude signal was observed within and between cortical bone samples. For the two-dimensional gradient echo sequence implemented in this study, a least-squares linear fit determined the percentage change in signal to be (0.90 ± 0.01)%/°C. This relationship was used to estimate temperature changes observed in the HIFU experiment and these temperatures agreed well with those measured from an implanted fiber-optic sensor. This method appears capable of displaying changes related to temperature in cortical bone and could improve the safety of MR-HIFU treatments. Further investigations into the sensitivity of the technique in vivo are warranted. © 2014 Wiley Periodicals, Inc.

Experimental verification of the Acuros XB and AAA dose calculation adjacent to heterogeneous media for IMRT and RapidArc of nasopharygeal carcinoma.

PubMed

Kan, Monica W K; Leung, Lucullus H T; So, Ronald W K; Yu, Peter K N

2013-03-01

To compare the doses calculated by the Acuros XB (AXB) algorithm and analytical anisotropic algorithm (AAA) with experimentally measured data adjacent to and within heterogeneous medium using intensity modulated radiation therapy (IMRT) and RapidArc(®) (RA) volumetric arc therapy plans for nasopharygeal carcinoma (NPC). Two-dimensional dose distribution immediately adjacent to both air and bone inserts of a rectangular tissue equivalent phantom irradiated using IMRT and RA plans for NPC cases were measured with GafChromic(®) EBT3 films. Doses near and within the nasopharygeal (NP) region of an anthropomorphic phantom containing heterogeneous medium were also measured with thermoluminescent dosimeters (TLD) and EBT3 films. The measured data were then compared with the data calculated by AAA and AXB. For AXB, dose calculations were performed using both dose-to-medium (AXB_Dm) and dose-to-water (AXB_Dw) options. Furthermore, target dose differences between AAA and AXB were analyzed for the corresponding real patients. The comparison of real patient plans was performed by stratifying the targets into components of different densities, including tissue, bone, and air. For the verification of planar dose distribution adjacent to air and bone using the rectangular phantom, the percentages of pixels that passed the gamma analysis with the ± 3%/3mm criteria were 98.7%, 99.5%, and 97.7% on the axial plane for AAA, AXB_Dm, and AXB_Dw, respectively, averaged over all IMRT and RA plans, while they were 97.6%, 98.2%, and 97.7%, respectively, on the coronal plane. For the verification of planar dose distribution within the NP region of the anthropomorphic phantom, the percentages of pixels that passed the gamma analysis with the ± 3%/3mm criteria were 95.1%, 91.3%, and 99.0% for AAA, AXB_Dm, and AXB_Dw, respectively, averaged over all IMRT and RA plans. Within the NP region where air and bone were present, the film measurements represented the dose close to unit density water

Bone-like apatite layer formation on hydroxyapatite prepared by spark plasma sintering (SPS).

PubMed

Gu, Y W; Khor, K A; Cheang, P

2004-08-01

Hydroxyapatite (HA) compacts with high density and superior mechanical properties were fabricated by spark plasma sintering (SPS) using spray-dried HA powders as feedstock. The formation of bone-like apatite layer on SPS consolidated HA compacts were investigated by soaking the HA compacts in simulated body fluid (SBF) for various periods (maximum of 28 days). The structural changes in HA post-SBF were analyzed with scanning electron microscopy, grazing incidence X-ray diffraction and X-ray photoelectron spectroscopy. It was found that a layer consisting microcrystalline carbonate-containing hydroxyapatite was formed on the surface of HA compacts after soaking for 24h. The formation mechanism of apatite on the surface of HA compacts after soaking in SBF was attributed to the ion exchange between HA compacts and the SBF solution. The increase in ionic concentration of calcium and phosphorus as well as the increase in pH after SBF immersion resulted in an increase in ionic activity product of apatite in the solution, and provided a specific surface with a low interface energy that is conducive to the nucleation of apatite on the surface of HA compacts.

Microstructure and thermal characterization of dense bone and metals for biomedical use

NASA Astrophysics Data System (ADS)

Rodríguez, G. Peña; Calderón, A.; Hernández, R. A. Muñoz; Orea, A. Cruz; Méndez, M.; Sinencio, F. Sánchez

2000-10-01

We present a microstructural study and thermal diffusivity measurements at room temperature in two different sections of bull dense bone, bull bone and commercial hydroxyapatite, the last two in powder form. A comparison was realised between these measured values and those obtained from metallic samples frequently used in implants, as high purity titanium and 316L stainless steel. Our results show that the porosity and its orientation in the bone are two important factors for the heat flux through the bone. On the other hand, we obtained that the hydroxyapatite, in compact powder form, presents a thermal diffusivity value close to those obtained for the samples of bone which gives a good thermal agreement between these materials. Finally, it was obtained at one order of magnitude difference between the thermal diffusivity values of metallic samples and those corresponding values to bone and hydroxyapatite being this difference greater in titanium than in stainless steel.

Food Impaction and Periodontal/Peri-Implant Tissue Conditions in Relation to the Embrasure Dimensions Between Implant-Supported Fixed Dental Prostheses and Adjacent Teeth: A Cross-Sectional Study.

PubMed

Jeong, Jin-Seok; Chang, Moontaek

2015-12-01

Food impaction and periodontal/peri-implant tissue conditions were evaluated in relation to the embrasure dimensions between implant-supported fixed dental prostheses (FDPs) and adjacent teeth. A total of 215 embrasures of 150 FDPs in 100 patients (55 males and 45 females, aged 27 to 83 years; mean age: 56 years) were included in the study. Clinical assessments of the periodontal/peri-implant mucosal conditions, radiographic assessments of embrasure dimensions, and overall patient satisfaction were used as explanatory variables for the food impaction and periodontal/peri-implant tissue conditions adjacent to implant-supported FDPs in the generalized estimating equation (GEE) analysis. Food impaction was reported in 96 (44.7%) of 215 embrasures between implant-supported FDPs and adjacent teeth. Food impaction was reported more frequently in the embrasures with proximal contact loss than in those with tight contact (P = 0.009). Overall patient satisfaction was influenced negatively by food impaction in the proximal embrasures (P = 0.01). Among embrasure dimensions, only the embrasure surface area (ESA) significantly influenced food impaction (P = 0.03). Significant influences of various embrasure dimensions on the periodontal/peri-implant mucosal conditions and bone level at the implant were found in the univariate and multivariate GEE analyses. Food impaction between implant-supported FDPs and adjacent teeth occurred more frequently when proximal contact was lost and ESA increased. Food impaction negatively affected overall patient satisfaction. Embrasure dimensions influenced the periodontal/peri-implant mucosal conditions and bone level at the implant.

Preparation of Laponite Bioceramics for Potential Bone Tissue Engineering Applications

PubMed Central

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

2014-01-01

We report a facile approach to preparing laponite (LAP) bioceramics via sintering LAP powder compacts for bone tissue engineering applications. The sintering behavior and mechanical properties of LAP compacts under different temperatures, heating rates, and soaking times were investigated. We show that LAP bioceramic with a smooth and porous surface can be formed at 800°C with a heating rate of 5°C/h for 6 h under air. The formed LAP bioceramic was systematically characterized via different methods. Our results reveal that the LAP bioceramic possesses an excellent surface hydrophilicity and serum absorption capacity, and good cytocompatibility and hemocompatibility as demonstrated by resazurin reduction assay of rat mesenchymal stem cells (rMSCs) and hemolytic assay of pig red blood cells, respectively. The potential bone tissue engineering applicability of LAP bioceramic was explored by studying the surface mineralization behavior via soaking in simulated body fluid (SBF), as well as the surface cellular response of rMSCs. Our results suggest that LAP bioceramic is able to induce hydroxyapatite deposition on its surface when soaked in SBF and rMSCs can proliferate well on the LAP bioceramic surface. Most strikingly, alkaline phosphatase activity together with alizarin red staining results reveal that the produced LAP bioceramic is able to induce osteoblast differentiation of rMSCs in growth medium without any inducing factors. Finally, in vivo animal implantation, acute systemic toxicity test and hematoxylin and eosin (H&E)-staining data demonstrate that the prepared LAP bioceramic displays an excellent biosafety and is able to heal the bone defect. Findings from this study suggest that the developed LAP bioceramic holds a great promise for treating bone defects in bone tissue engineering. PMID:24955961

The influence of bone damage on press-fit mechanics.

PubMed

Bishop, Nicholas E; Höhn, Jan-Christian; Rothstock, Stephan; Damm, Niklas B; Morlock, Michael M

2014-04-11

Press-fitting is used to anchor uncemented implants in bone. It relies in part on friction resistance to relative motion at the implant-bone interface to allow bone ingrowth and long-term stability. Frictional shear capacity is related to the interference fit of the implant and the roughness of its surface. It was hypothesised here that a rough implant could generate trabecular bone damage during implantation, which would reduce its stability. A device was constructed to simulate implantation by displacement of angled platens with varying surface finishes (polished, beaded and flaked) onto the surface of an embedded trabecular bone cube, to different nominal interferences. Push-in (implantation) and Pull-out forces were measured and micro-CT scans were made before and after testing to assess permanent bone deformation. Depth of permanent trabecular bone deformation ('damage'), Pull-out force and Radial force all increased with implantation displacement and with implantation force, for all surface roughnesses. The proposed hypothesis was rejected, since primary stability did not decrease with trabecular bone damage. In fact, Pull-out force linearly increased with push-in force, independently of trabecular bone damage or implant surface. This similar behaviour for the different surfaces might be explained by the compaction of bone into the surfaces during push-in so that Pull-out resistance is governed by bone-on-bone, rather than implant surface-on-bone friction. The data suggest that maximum stability is achieved for the maximum implantation force possible (regardless of trabecular bone damage or surface roughness), but this must be limited to prevent periprosthetic cortical bone fracture, patient damage and component malpositioning. Copyright © 2014 Elsevier Ltd. All rights reserved.

New insights to the role of aryl hydrocarbon receptor in bone phenotype and in dioxin-induced modulation of bone microarchitecture and material properties

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

Herlin, Maria, E-mail: maria.herlin@ki.se; Finnilä, Mikko A.J., E-mail: mikko.finnila@oulu.fi; Department of Anatomy and Cell Biology, Institute of Biomedicine, University of Oulu, Oulu

Bone is a target for high affinity aryl hydrocarbon receptor (AHR) ligands, such as dioxins. Although bone morphology, mineral density and strength are sensitive endpoints of dioxin toxicity, less is known about effects on bone microarchitecture and material properties. This study characterizes TCDD-induced modulations of bone tissue, and the role of AHR in dioxin-induced bone toxicity and for normal bone phenotype. Six AHR-knockout (Ahr{sup −/−}) and wild-type (Ahr{sup +/+}) mice of both genders were exposed to TCDD weekly for 10 weeks, at a total dose of 200 μg/kg bw. Bones were examined with micro-computed tomography, nanoindentation and biomechanical testing. Serummore » levels of bone remodeling markers were analyzed, and the expression of genes related to osteogenic differentiation was profiled using PCR array. In Ahr{sup +/+} mice, TCDD-exposure resulted in harder bone matrix, thinner and more porous cortical bone, and a more compact trabecular bone compartment. Bone remodeling markers and altered expression of a number of osteogenesis related genes indicated imbalanced bone remodeling. Untreated Ahr{sup −/−} mice displayed a slightly modified bone phenotype as compared with untreated Ahr{sup +/+} mice, while TCDD exposure caused only a few changes in bones of Ahr{sup −/−} mice. Part of the effects of both TCDD-exposure and AHR-deficiency were gender dependent. In conclusion, exposure of adult mice to TCDD resulted in harder bone matrix, thinner cortical bone, mechanically weaker bones and most notably, increased trabecular bone volume fraction in Ahr{sup +/+} mice. AHR is involved in bone development of a normal bone phenotype, and is crucial for manifestation of TCDD-induced bone alterations. - Highlights: • TCDD disrupts bone remodeling resulting in altered cortical and trabecular bone. • In trabecular bone an anabolic effect is observed. • Cortical bone is thinner, more porous, harder, stiffer and mechanically weaker. • AHR

[Reconstruction of tangential and circular infected bone defects].

PubMed

Schmidt, H G; Neikes, M; Zimmer, W

1987-12-01

In the treatment of bone infections the reconstruction and rehabilitation of bone defects is a problem that often requires treatment secondary to curative treatment of the infection. For the reconstruction of smaller and more extensive defects we used predominantly (92.7%) autogenous (autologous) untreated spongiosa and in only 7% of the cases allogenic (homologous) spongiosa from an organ bank, this being added if necessary. Recently the additionally introduced vascularized bone chip has become a useful extension of the therapy concept. The problems and complications of defect reconstruction are demonstrated for 705 cases of bone infection with 472 defects of different sizes, based on a comprehensive classification with defect calculation. Surgical technical approach and special aspects of after-treatment are described, as well as the results for every group of cases. We achieved stability and freedom from infection in a total of 93.7% of the patients. As was to be expected, the problems grow with the size of the defect. Particularly problematic are joint infections with adjacent extensive circular defect.

Histological and compositional responses of bone to immobilization and other experimental conditions

NASA Technical Reports Server (NTRS)

Brown, R. J.; Niklowitz, W. J.

1985-01-01

Histological techniques were utilized for evaluating progressive changes in tibial compact bone in adult male monkeys during chronic studies of immobilization-associated osteopenia. The animals were restrained in a semirecumbent position which reduces normally occurring stresses in the lower extremities and results in bone mass loss. The longest immobilization studies were of seven months duration. Losses of haversian bone tended to occur predominatly in the proximal tibia and were characterized by increased activation with excessive depth of penetration of osteoclastic activity. There was no apparent regulation of the size and orientation of resorption cavities. Rapid bone loss seen during 10 weeks of immobilization appeared to be due to unrestrained osteoclastic activity without controls and regulation which are characteristic of adaptive systems. The general pattern of loss persisted throughout 7 months of immobilization. Clear cut evidence of a formation phase in haversian bone was seen only after two months of reambulation.

Effect of recombinant human bone morphogenetic protein-2 on bone regeneration and osseointegration of dental implants.

PubMed

Sykaras, N; Triplett, R G; Nunn, M E; Iacopino, A M; Opperman, L A

2001-08-01

Recombinant human bone morphogenetic protein-2 (rhBMP-2) induced bone regeneration and osseointegration was evaluated in bony defects created within the hollow chamber of endosseous dental implants in 14 foxhound dogs. Bilateral extractions of mandibular premolars were performed and surgical implantation of 104 hollow cylinder implants followed after 8 weeks of healing. Experimental implants had their hollow chamber filled with 20 microg of rhBMP-2 delivered with a bovine collagen carrier, whereas the control implants had their apical chamber left empty. Dogs were followed for 2, 4, 8 and 12 weeks. Histomorphometric evaluation and immunohistochemical analysis were performed. Minimal bone was regenerated at 2 weeks for both groups. At 4 weeks, bone fill averaged 23.48% for the rhBMP-2 and 5.98% for the control group (P<0.05). At 8 weeks, mean bone fill was 20.94% and 7.75% for the rhBMP-2 and the controls, respectively (P<0.05). At 12 weeks, mean bone fill was 31.39% and 24.31% for the rhBMP-2 and control implants, respectively (P>0.05). Bone-implant contact (BIC) increased for both groups over time and at 8 weeks the rhBMP-2 BIC value was 18.65% and for the control 7.22% (P<0.05). At 12 weeks, the BIC was 43.78% and 21.05% for the rhBMP-2 and the control group, respectively (P<0.05). Immunohistochemical staining for type II collagen was positive only for parts of the collagen carrier and formation of cartilaginous intermediate was not observed in any of the specimens. The results suggest that, in confined defects adjacent to dental implants, rhBMP-2 can induce bone regeneration in close apposition to the implant surface.

(U) Influence of Compaction Model Form on Planar and Cylindrical Compaction Geometries

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

Fredenburg, David A.; Carney, Theodore Clayton; Fichtl, Christopher Allen

The dynamic compaction response of CeO 2 is examined within the frameworks of the Ramp and P-a compaction models. Hydrocode calculations simulating the dynamic response of CeO 2 at several distinct pressures within the compaction region are investigated in both planar and cylindrically convergent geometries. Findings suggest additional validation of the compaction models is warranted under complex loading configurations.

Compact Polarimetry Potentials

NASA Technical Reports Server (NTRS)

Truong-Loi, My-Linh; Dubois-Fernandez, Pascale; Pottier, Eric

2011-01-01

The goal of this study is to show the potential of a compact-pol SAR system for vegetation applications. Compact-pol concept has been suggested to minimize the system design while maximize the information and is declined as the ?/4, ?/2 and hybrid modes. In this paper, the applications such as biomass and vegetation height estimates are first presented, then, the equivalence between compact-pol data simulated from full-pol data and compact-pol data processed from raw data as such is shown. Finally, a calibration procedure using external targets is proposed.

Alveolar distraction osteogenesis: revive and restore the native bone.

PubMed

Sant, Sumedha; Jagtap, Amit

2009-12-01

In prosthodontics, knife-edge bony alveolar ridges can cause a problem in their rehabilitation. The distraction osteogenesis process raises the medullary component of the alveolus, allowing the labial plate of the existing natural bone to be displaced. This process involves mobilization, transport, and fixation of a healthy segment of bone adjacent to the deficient site. It entails use of the gradual controlled displacement of surgically created fractures, which results in simultaneous expansion of soft tissue and bone volume. A mechanical device, the alveolar distraction device, is used for this purpose. This modality of treatment can be used in implant dentistry cases for rehabilitation of resorbed ridges. The objective of this overview is to explain this procedure wherein the alveolar housing, including the osseous and soft-tissue components, is enlarged in a single, simultaneous process, which makes creation of an appropriate alveolar morphology possible.

[Experimental study of repairing bone defect with tissue engineered bone seeded with autologous red bone marrow and wrapped by pedicled fascial flap].

PubMed

Yang, Xinming; Shi, Wei; Du, Yakun; Meng, Xianyong; Yin, Yanlin

2009-10-01

To investigate the effect of repairing bone defect with tissue engineered bone seeded with the autologous red bone marrow (ARBM) and wrapped by the pedicled fascial flap and provide experimental foundation for clinical application. Thirty-two New Zealand white rabbits (male and/or female) aged 4-5 months old and weighing 2.0-2.5 kg were used to make the experimental model of bilateral 2 cm defect of the long bone and the periosteum in the radius. The tissue engineered bone was prepared by seeding the ARBM obtained from the rabbits on the osteoinductive absorbing material containing BMP. The left side of the experimental model underwent the implantation of autologous tissue engineered bone serving as the control group (group A). While the right side was designed as the experimental group (group B), one 5 cm x 3 cm fascial flap pedicled on the nameless blood vessel along with its capillary network adjacent to the bone defect was prepared using microsurgical technology, and the autologous tissue engineered bone wrapped by the fascial flap was used to fill the bone defect. At 4, 8, 12, and 16 weeks after operation, X-ray exam, absorbance (A) value test, gross morphology and histology observation, morphology quantitative analysis of bone in the reparative area, vascular image analysis on the boundary area were conducted. X-ray films, gross morphology observation, and histology observation: group B was superior to group A in terms of the growth of blood vessel into the implant, the quantity and the speed of the bone trabecula and the cartilage tissue formation, the development of mature bone structure, the remodeling of shaft structure, the reopen of marrow cavity, and the absorbance and degradation of the implant. A value: there was significant difference between two groups 8, 12, and 16 weeks after operation (P < 0.05), and there were significant differences among those three time points in groups A and B (P < 0.05). For the ratio of neonatal trabecula area to the

Numerical damage models using a structural approach: application in bones and ligaments

NASA Astrophysics Data System (ADS)

Arnoux, P. J.; Bonnoit, J.; Chabrand, P.; Jean, M.; Pithioux, M.

2002-01-01

The purpose of the present study was to apply knowledge of structural properties to perform numerical simulations with models of bones and knee ligaments exposed to dynamic tensile loading leading to tissue damage. Compact bones and knee ligaments exhibit the same geometrical pattern in their different levels of structural hierarchy from the tropocollagen molecule to the fibre. Nevertheless, their mechanical behaviours differ considerably at the fibril level. These differences are due to the contribution of the joints in the microfibril-fibril-fibre assembly and to the mechanical properties of the structural components. Two finite element models of the fibrous bone and ligament structure were used to describe damage in terms of elastoplastic laws or joint decohesion processes.

Differential compaction behaviour of roller compacted granules of clopidogrel bisulphate polymorphs.

PubMed

Khomane, Kailas S; Bansal, Arvind K

2014-09-10

In the present work, in-die and out-of-die compaction behaviour of dry-granulated powders of clopidogrel bisulphate (CLP) polymorphs, form I and form II, was investigated using a fully instrumented rotary tablet press. Each polymorph was compacted at three different roller pressures [70.3 (S1), 105.5 (S2) and 140.6 (S3)kgf/cm(2)], and obtained granules were characterized for their physico-mechanical properties. Compaction data were analyzed for out-of-die compressibility, tabletability and compactibility profiles, and in-die Heckel, Kawakita and Walker analysis. The roller compacted granules of both forms showed markedly different tabletting behaviour. Roller pressure exhibited a trend on compaction behaviour of form I granules, whereas, in case of form II, the effect was insignificant. Tabletability of the six granule batches follows the order; I_S1>I_S2>I_S3>II_S1≈II_S2≈II_S3. In case of form I, the reduced tabletability of the granules compacted at higher roller pressure was attributed to the decreased compressibility and plastic deformation. This was confirmed by compressibility plot and various mathematical parameters derived from Heckel (Py), Kawakita (1/b) and Walker (W) equations. The reduced tabletability of form I granules was due to 'granule hardening' during roller compaction. On the other hand, insignificant effect of roller compaction on tabletting behaviour of form II granules was attributed to brittle fragmentation. The extensive fragmentation of granules offered new 'clean' surfaces and higher contact points that negated the effect of granule hardening. Copyright © 2014 Elsevier B.V. All rights reserved.

Measurements of elastic moduli of pharmaceutical compacts: a new methodology using double compaction on a compaction simulator.

PubMed

Mazel, Vincent; Busignies, Virginie; Diarra, Harona; Tchoreloff, Pierre

2012-06-01

The elastic properties of pharmaceutical powders play an important role during the compaction process. The elastic behavior can be represented by Young's modulus (E) and Poisson's ratio (v). However, during the compaction, the density of the powder bed changes and the moduli must be determined as a function of the porosity. This study proposes a new methodology to determine E and v as a function of the porosity using double compaction in an instrumented compaction simulator. Precompression is used to form the compact, and the elastic properties are measured during the beginning of the main compaction. By measuring the axial and radial pressure and the powder bed thickness, E and v can be determined as a function of the porosity. Two excipients were studied, microcrystalline cellulose (MCC) and anhydrous calcium phosphate (aCP). The values of E measured are comparable to those obtained using the classical three-point bending test. Poisson's ratio was found to be close to 0.24 for aCP with only small variations with the porosity, and to increase with a decreasing porosity for MCC (0.23-0.38). The classical approximation of a value of 0.3 for ν of pharmaceutical powders should therefore be taken with caution. Copyright © 2012 Wiley Periodicals, Inc.

Non-Compact Cardiomyopathy or Ventricular Non-Compact Syndrome?

PubMed Central

2014-01-01

Ventricular myocardial non-compaction has been recognized and defined as a genetic cardiomyopathy by American Heart Association since 2006. The argument on the nomenclature and pathogenesis of this kind of ventricular myocardial non-compaction characterized by regional ventricular wall thickening and deep trabecular recesses often complicated with chronic heart failure, arrhythmia and thromboembolism and usually overlap the genetics and phenotypes of other kind of genetic or mixed cardiomyopathy still exist. The proper classification and correct nomenclature of the non-compact ventricles will contribute to the precisely and completely understanding of etiology and its related patho-physiological mechanism for a better risk stratification and more personalized therapy of the disease individually. All of the genetic heterogeneity and phenotypical overlap and the variety in histopathological, electromechanical and clinical presentation indicates that some of the cardiomyopathies might just be the different consequence of myocardial development variations related to gene mutation and phenotype of one or group genes induced by the interacted and disturbed process of gene modulation at different links of gene function expression and some other etiologies. This review aims to establish a new concept of "ventricular non-compaction syndrome" based on the demonstration of the current findings of etiology, epidemiology, histopathology and echocardiography related to the disorder of ventricular myocardial compaction and myocardial electromechanical function development. PMID:25580189

Facial nerve palsy associated with a cystic lesion of the temporal bone.

PubMed

Kim, Na Hyun; Shin, Seung-Ho

2014-03-01

Facial nerve palsy results in the loss of facial expression and is most commonly caused by a benign, self-limiting inflammatory condition known as Bell palsy. However, there are other conditions that may cause facial paralysis, such as neoplastic conditions of the facial nerve, traumatic nerve injury, and temporal bone lesions. We present a case of facial nerve palsy concurrent with a benign cystic lesion of the temporal bone, adjacent to the tympanic segment of the facial nerve. The patient's symptoms subsided after facial nerve decompression via a transmastoid approach.

A compact DD neutron generator-based NAA system to quantify manganese (Mn) in bone in vivo.

PubMed

Liu, Yingzi; Byrne, Patrick; Wang, Haoyu; Koltick, David; Zheng, Wei; Nie, Linda H

2014-09-01

A deuterium-deuterium (DD) neutron generator-based neutron activation analysis (NAA) system has been developed to quantify metals, including manganese (Mn), in bone in vivo. A DD neutron generator with a flux of up to 3*10(9) neutrons s(-1) was set up in our lab for this purpose. Optimized settings, including moderator, reflector, and shielding material and thickness, were selected based on Monte Carlo (MC) simulations conducted in our previous work. Hand phantoms doped with different Mn concentrations were irradiated using the optimized DD neutron generator irradiation system. The Mn characteristic γ-rays were collected by an HPGe detector system with 100% relative efficiency. The calibration line of the Mn/calcium (Ca) count ratio versus bone Mn concentration was obtained (R(2) = 0.99) using the hand phantoms. The detection limit (DL) was calculated to be about 1.05 μg g(-1) dry bone (ppm) with an equivalent dose of 85.4 mSv to the hand. The DL can be reduced to 0.74 ppm by using two 100% HPGe detectors. The whole body effective dose delivered to the irradiated subject was calculated to be about 17 μSv. Given the average normal bone Mn concentration of 1 ppm in the general population, this system is promising for in vivo bone Mn quantification in humans.

Shell bone histology of the long-necked chelid Yaminuechelys (Testudines: Pleurodira) from the late Cretaceous—early Palaeocene of Patagonia with comments on the histogenesis of bone ornamentation

NASA Astrophysics Data System (ADS)

Jannello, Juan Marcos; Cerda, Ignacio A.; de la Fuente, Marcelo S.

2016-04-01

Yaminuechelys is a long-necked chelid turtle whose remains have been recovered from outcrops of the Santonian-Maastrichtian and Danian of South America. With the purpose of providing data about shell sculpturing origin and palaeoecology, the bone histology of several shell elements (including neural, costal, peripheral and plastral plates) of Yaminuechelys is described herein. Histological analysis reveals that Yaminuechelys shares with Chelidae the presence of interwoven structural fibre bundles in the external cortex, and parallel-fibred bone of the internal cortex. The presence of resorption lines in several samples indicates that the particular ornamentation of the external surfaces originated, at least in part, by focalized resorption and new bone deposition. This mechanism for ornamentation origin and maintenance is here described for the first time in a turtle. Compactness of the shell bones is consistent with an aquatic habitat, which supports previous hypothesis based on palaeoenvironmental and morphological data.

Water-level altitudes 2013 and water-level changes in the Chicot, Evangeline, and Jasper aquifers and compaction 1973--2012 in the Chicot and Evangeline aquifers, Houston-Galveston region, Texas

USGS Publications Warehouse

Kasmarek, Mark C.; Johnson, Michaela R.; Ramage, Jason K.

2013-01-01

Compaction of subsurface sediments (mostly in the clay and silt layers) of the Chicot and Evangeline aquifers was recorded continuously by 13 borehole extensometers at 11 sites that were either activated or installed between 1973 and 1980. For the period of record beginning in 1973 (or later depending on activation or installation date) and ending in December 2012, cumulative measured compaction by 12 of the 13 extensometers ranged from 0.100 ft at the Texas City-Moses Lake extensometer to 3.632 ft at the Addicks extensometer (data were used from only one of two extensometers at one site). The rate of compaction varies from site to site because of differences in groundwater withdrawals near each site and differences among sites in the clay-to-sand ratio in the subsurface sediments. Therefore, it is not possible to extrapolate or infer a rate of compaction for adjacent areas based on the rate of compaction measured at a nearby extensometer.

Stem cell niches and other factors that influence the sensitivity of bone marrow to radiation-induced bone cancer and leukaemia in children and adults

PubMed Central

Richardson, Richard B

2011-01-01

Purpose: This paper reviews and reassesses the internationally accepted niches or ‘targets’ in bone marrow that are sensitive to the induction of leukaemia and primary bone cancer by radiation. Conclusions: The hypoxic conditions of the 10 μm thick endosteal/osteoblastic niche where preleukemic stem cells and hematopoietic stem cells (HSC) reside provides a radioprotective microenvironment that is 2-to 3-fold less radiosensitive than vascular niches. This supports partitioning the whole marrow target between the low haematological cancer risk of irradiating HSC in the endosteum and the vascular niches within central marrow. There is a greater risk of induced bone cancer when irradiating a 50 μm thick peripheral marrow adjacent to the remodelling/reforming portion of the trabecular bone surface, rather than marrow next to the quiescent bone surface. This choice of partitioned bone cancer target is substantiated by the greater radiosensitivity of: (i) Bone with high remodelling rates, (ii) the young, (iii) individuals with hypermetabolic benign diseases of bone, and (iv) the epidemiology of alpha-emitting exposures. Evidence is given to show that the absence of excess bone-cancer in atomic-bomb survivors may be partially related to the extremely low prevalence among Japanese of Paget's disease of bone. Radiation-induced fibrosis and the wound healing response may be implicated in not only radiogenic bone cancers but also leukaemia. A novel biological mechanism for adaptive response, and possibility of dynamic targets, is advocated whereby stem cells migrate from vascular niches to stress-mitigated, hypoxic niches. PMID:21204614

Chitosan-poly(lactide-co-glycolide) microsphere-based scaffolds for bone tissue engineering: in vitro degradation and in vivo bone regeneration studies.

PubMed

Jiang, Tao; Nukavarapu, Syam P; Deng, Meng; Jabbarzadeh, Ehsan; Kofron, Michelle D; Doty, Stephen B; Abdel-Fattah, Wafa I; Laurencin, Cato T

2010-09-01

Natural polymer chitosan and synthetic polymer poly(lactide-co-glycolide) (PLAGA) have been investigated for a variety of tissue engineering applications. We have previously reported the fabrication and in vitro evaluation of a novel chitosan/PLAGA sintered microsphere scaffold for load-bearing bone tissue engineering applications. In this study, the in vitro degradation characteristics of the chitosan/PLAGA scaffold and the in vivo bone formation capacity of the chitosan/PLAGA-based scaffolds in a rabbit ulnar critical-sized-defect model were investigated. The chitosan/PLAGA scaffold showed slower degradation than the PLAGA scaffold in vitro. Although chitosan/PLAGA scaffold showed a gradual decrease in compressive properties during the 12-week degradation period, the compressive strength and compressive modulus remained in the range of human trabecular bone. Chitosan/PLAGA-based scaffolds were able to guide bone formation in a rabbit ulnar critical-sized-defect model. Microcomputed tomography analysis demonstrated that successful bridging of the critical-sized defect on the sides both adjacent to and away from the radius occurred using chitosan/PLAGA-based scaffolds. Immobilization of heparin and recombinant human bone morphogenetic protein-2 on the chitosan/PLAGA scaffold surface promoted early bone formation as evidenced by complete bridging of the defect along the radius and significantly enhanced mechanical properties when compared to the chitosan/PLAGA scaffold. Furthermore, histological analysis suggested that chitosan/PLAGA-based scaffolds supported normal bone formation via intramembranous formation. 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Self-fitting shape memory polymer foam inducing bone regeneration: A rabbit femoral defect study.

PubMed

Xie, Ruiqi; Hu, Jinlian; Hoffmann, Oskar; Zhang, Yuanchi; Ng, Frankie; Qin, Tingwu; Guo, Xia

2018-04-01

Although tissue engineering has been attracted greatly for healing of critical-sized bone defects, great efforts for improvement are still being made in scaffold design. In particular, bone regeneration would be enhanced if a scaffold precisely matches the contour of bone defects, especially if it could be implanted into the human body conveniently and safely. In this study, polyurethane/hydroxyapatite-based shape memory polymer (SMP) foam was fabricated as a scaffold substrate to facilitate bone regeneration. The minimally invasive delivery and the self-fitting behavior of the SMP foam were systematically evaluated to demonstrate its feasibility in the treatment of bone defects in vivo. Results showed that the SMP foam could be conveniently implanted into bone defects with a compact shape. Subsequently, it self-matched the boundary of bone defects upon shape-recovery activation in vivo. Micro-computed tomography determined that bone ingrowth initiated at the periphery of the SMP foam with a constant decrease towards the inside. Successful vascularization and bone remodeling were also demonstrated by histological analysis. Thus, our results indicate that the SMP foam demonstrated great potential for bone regeneration. Copyright © 2018 Elsevier B.V. All rights reserved.

Hydraulic conductivity of compacted zeolites.

PubMed

Oren, A Hakan; Ozdamar, Tuğçe

2013-06-01

Hydraulic conductivities of compacted zeolites were investigated as a function of compaction water content and zeolite particle size. Initially, the compaction characteristics of zeolites were determined. The compaction test results showed that maximum dry unit weight (γ(dmax)) of fine zeolite was greater than that of granular zeolites. The γ(dmax) of compacted zeolites was between 1.01 and 1.17 Mg m(-3) and optimum water content (w(opt)) was between 38% and 53%. Regardless of zeolite particle size, compacted zeolites had low γ(dmax) and high w(opt) when compared with compacted natural soils. Then, hydraulic conductivity tests were run on compacted zeolites. The hydraulic conductivity values were within the range of 2.0 × 10(-3) cm s(-1) to 1.1 × 10(-7) cm s(-1). Hydraulic conductivity of all compacted zeolites decreased almost 50 times as the water content increased. It is noteworthy that hydraulic conductivity of compacted zeolite was strongly dependent on the zeolite particle size. The hydraulic conductivity decreased almost three orders of magnitude up to 39% fine content; then, it remained almost unchanged beyond 39%. Only one report was found in the literature on the hydraulic conductivity of compacted zeolite, which is in agreement with the findings of this study.

Dynamic Mechanical Testing Techniques for Cortical and Cancellous Bone

NASA Astrophysics Data System (ADS)

Cloete, Trevor

2017-06-01

Bone fracture typically occurs as an impact loading event (sporting accidents, vehicle collisions), the simulation of which requires in-depth understanding of dynamic bone behavior. Bone is a natural composite material with a complex multi length-scale hierarchical microstructure. At a macroscopic level, it is classified into hard/compact cortical bone and soft/spongy cancellous (trabecular) bone, though both are low-impedance materials relative to steels. Cortical bone is predominant in long bones, while in complex bone geometries (joints, flat bones) a cancellous bone core supports a thin cortical shell. Bone has primarily been studied at quasi-static strain rates (ɛ˙ < 1s-1), with some dynamic studies (300s-1 <ɛ˙ < 3000s-1), but rarely at intermediate strain rates (ISR) (1s-1 <ɛ˙ < 100s-1). The data shows bone to be viscoelastic, which suggests that more dynamic and ISR data is required. Furthermore, bone exhibits quasi-brittle failure, with interrupted quasi-static tests revealing a strong microstructure dependence. However, bone specimens are typically destroyed during dynamic tests, leading to a lack of dynamic microstructural damage investigations. In this paper, a short overview of dynamic bone testing is presented to give context to the challenges of testing low impedance, strain-rate dependent, non-linear, visco-elastic-brittle materials. Recent state-of-the-art experimental developments in dynamic bone testing are reviewed, with emphasis on pulse shaping, momentum trapping and ISR testing. These techniques allow for dynamic bone testing at small strains and near-constant strain rates with intact specimen recovery. The results are compared to those obtained with varying strain rate tests. Interrupted dynamic test results with microstructural analysis of the recovered specimens are presented and discussed. The paper concludes with a discussion of the experimental and modeling challenges that lie ahead in the field of dynamic bone behavior. The

Stereomicroscopic evaluation of the joint cartilage and bone tissue in osteoporosis

NASA Astrophysics Data System (ADS)

Vasile, Liliana; Torok, Rodica; Deleanu, Bogdan; Marchese, Cristian; Valeanu, Adina; Bodea, Rodica

2012-06-01

Aim of the study. Assessment by stereomicroscopy of the severity of lesions in osteoporotic bone at both sexes and to correlate micro-and macro-bone fracture due to low bone density values with the disease evolution. Material and method: The study material consists of fragments of bone from the femoral head, vertebral bone, costal and iliac crest biopsy obtained from patients aged over 70 years, female and male, treated in the County Hospital of Timisoara, Department of Orthopedics. For the purpose of studying the samples in stereomicroscopy and trough polarized light it has been used the Olympus Microscope SZ ×7 and an Olympus camera with 2,5 × digital zoom and a 3× optical zoom in the Vest Politechnic Univesity. Results and discussions: Subchondral bone presents osteolysis associated with a osteoporotic bone transformation. Pseudocystic chondrolisis was noted in the osteoarticular cartilage, in addition with areas of hemorrhagic postfractural necrosis. The osteoporotic bone exhibits ischemic necrosis and focal hemorrhagic necrosis adjacent fracture. Microporosity pattern of the bone observed by stereomicroscopy correspond to the spongy bone osteoporosis images. Morphometry of the bone spiculi reveals length of 154.88 and 498.32 μ. In men we found a greater thickness of bone trabeculi compared with bone texture porosity in women. The subchondral bone supports and fulfills an important role in transmitting forces from the overlying articular cartilage inducing the bone resorbtion. The femoral head fracture may be the final event of many accumulated bone microcracks. Conclusions: Bone fragility depends not only of the spongy bone but also of the cortical bone properties. Osteolysis produced by loss of balance in the process of remodeling in favor of bone resorption leads to the thinning of the subchondral bone at both sexes.

Fabrication of porous low crystalline calcite block by carbonation of calcium hydroxide compact.

PubMed

Matsuya, Shigeki; Lin, Xin; Udoh, Koh-ichi; Nakagawa, Masaharu; Shimogoryo, Ryoji; Terada, Yoshihiro; Ishikawa, Kunio

2007-07-01

Calcium carbonate (CaCO(3)) has been widely used as a bone substitute material because of its excellent tissue response and good resorbability. In this experimental study, we propose a new method obtaining porous CaCO(3) monolith for an artificial bone substitute. In the method, calcium hydroxide compacts were exposed to carbon dioxide saturated with water vapor at room temperature. Carbonation completed within 3 days and calcite was the only product. The mechanical strength of CaCO(3) monolith increased with carbonation period and molding pressure. Development of mechanical strength proceeded through two steps; the first rapid increase by bonding with calcite layer formed at the surface of calcium hydroxide particles and the latter increase by the full conversion of calcium hydroxide to calcite. The latter process was thought to be controlled by the diffusion of CO(2) through micropores in the surface calcite layer. Porosity of calcite blocks thus prepared had 36.8-48.1% depending on molding pressure between 1 MPa and 5 MPa. We concluded that the present method may be useful for the preparation of bone substitutes or the preparation of source material for bone substitutes since this method succeeded in fabricating a low-crystalline, and thus a highly reactive, porous calcite block.

VIBRATION COMPACTION

DOEpatents

Hauth, J.J.

1962-07-01

A method of compacting a powder in a metal container is described including the steps of vibrating the container at above and below the resonant frequency and also sweeping the frequency of vibration across the resonant frequency several times thereby following the change in resonant frequency caused by compaction of the powder. (AEC)

Thermal Model to Investigate the Temperature in Bone Grinding for Skull Base Neurosurgery

PubMed Central

Zhang, Lihui; Tai, Bruce L.; Wang, Guangjun; Zhang, Kuibang; Sullivan, Stephen; Shih, Albert J.

2013-01-01

This study develops a thermal model utilizing the inverse heat transfer method (IHTM) to investigate the bone grinding temperature created by a spherical diamond tool used for skull base neurosurgery. Bone grinding is a critical procedure in the expanded endonasal approach to remove the cranial bone and access to the skull base tumor via nasal corridor. The heat is generated during grinding and could damage the nerve or coagulate the blood in the carotid artery adjacent to the bone. The finite element analysis is adopted to investigate the grinding-induced bone temperature rise. The heat source distribution is defined by the thermal model, and the temperature distribution is solved using the IHTM with experimental inputs. Grinding experiments were conducted on a bovine cortical bone with embedded thermocouples. Results show significant temperature rise in bone grinding. Using 50°C as the threshold, the thermal injury can propagate about 3 mm in the traverse direction, and 3 mm below the ground surface under the dry grinding condition. The presented methodology demonstrated the capability of being a thermal analysis tool for bone grinding study. PMID:23683875

Thermal model to investigate the temperature in bone grinding for skull base neurosurgery.

PubMed

Zhang, Lihui; Tai, Bruce L; Wang, Guangjun; Zhang, Kuibang; Sullivan, Stephen; Shih, Albert J

2013-10-01

This study develops a thermal model utilizing the inverse heat transfer method (IHTM) to investigate the bone grinding temperature created by a spherical diamond tool used for skull base neurosurgery. Bone grinding is a critical procedure in the expanded endonasal approach to remove the cranial bone and access to the skull base tumor via nasal corridor. The heat is generated during grinding and could damage the nerve or coagulate the blood in the carotid artery adjacent to the bone. The finite element analysis is adopted to investigate the grinding-induced bone temperature rise. The heat source distribution is defined by the thermal model, and the temperature distribution is solved using the IHTM with experimental inputs. Grinding experiments were conducted on a bovine cortical bone with embedded thermocouples. Results show significant temperature rise in bone grinding. Using 50°C as the threshold, the thermal injury can propagate about 3mm in the traverse direction, and 3mm below the ground surface under the dry grinding condition. The presented methodology demonstrated the capability of being a thermal analysis tool for bone grinding study. Copyright © 2013 IPEM. Published by Elsevier Ltd. All rights reserved.

[Effects of cuttlefish bone-bone morphogenetic protein composite material on osteogenesis and revascularization of bone defect in rats].

PubMed

Liu, Yuan; Yu, Jiang; Bai, Jie; Gu, Jin-song; Cai, Bin; Zhou, Xia

2013-12-01

To study the effects of cuttlefish bone-bone morphogenetic protein (BMP) composite material on osteogenesis and revascularization of bone defect in rats. The cuttlefish bone was formed into cylinder with the diameter of about 5 mm and height of about 2 mm after the shell was removed, and then it was soaked in the recombinant human BMP 2 to make a cuttlefish bone-BMP (CBB) composite material. Thirty SD rats, with a defect of skull in every rat, were divided into the CBB and pure cuttlefish bone (PCB) groups according to the random number table, with 15 rats in each group. The rats in the group CBB and group PCB were transplanted with the corresponding material to repair the skull defect. At post transplantation week (PTW) 4, 6, and 8, 5 rats from every group were sacrificed by exsanguination, and ink perfusion was performed. One day later, all the transplants and part of the skull surrounding the defect were harvested, and general observation was conducted at the same time. The specimens were paraffin sectioned for HE staining and Masson staining. The area of microvessel and the area of newborn bone were observed and analyzed through histopathological techniques and image collection system. Data were processed with the analysis of variance of factorial design and LSD test. The correlation between the area of microvessel and the area of newborn bone of the group CBB was analyzed with Pearson correlation analysis. (1) The general observation of the transplant region showed that the transplants were encapsulated by a capsule of fibrous connective tissue. The texture of capsule was soft and relatively thick at PTW 4. The texture was tenacious and thin, but rather compact at PTW 6 and 8. The transplants became gelatinous at PTW 4, and similar to the cartilage tissue at PTW 6 and 8. (2) Histological observation showed that the structure of the transplants in two groups was damaged at PTW 4. A moderate quantity of inflammatory cell infiltration could be observed. The

Tissue Microarray Analysis Applied to Bone Diagenesis

PubMed Central

Mello, Rafael Barrios; Silva, Maria Regina Regis; Alves, Maria Teresa Seixas; Evison, Martin Paul; Guimarães, Marco Aurelio; Francisco, Rafaella Arrabaca; Astolphi, Rafael Dias; Iwamura, Edna Sadayo Miazato

2017-01-01

Taphonomic processes affecting bone post mortem are important in forensic, archaeological and palaeontological investigations. In this study, the application of tissue microarray (TMA) analysis to a sample of femoral bone specimens from 20 exhumed individuals of known period of burial and age at death is described. TMA allows multiplexing of subsamples, permitting standardized comparative analysis of adjacent sections in 3-D and of representative cross-sections of a large number of specimens. Standard hematoxylin and eosin, periodic acid-Schiff and silver methenamine, and picrosirius red staining, and CD31 and CD34 immunohistochemistry were applied to TMA sections. Osteocyte and osteocyte lacuna counts, percent bone matrix loss, and fungal spheroid element counts could be measured and collagen fibre bundles observed in all specimens. Decalcification with 7% nitric acid proceeded more rapidly than with 0.5 M EDTA and may offer better preservation of histological and cellular structure. No endothelial cells could be detected using CD31 and CD34 immunohistochemistry. Correlation between osteocytes per lacuna and age at death may reflect reported age-related responses to microdamage. Methodological limitations and caveats, and results of the TMA analysis of post mortem diagenesis in bone are discussed, and implications for DNA survival and recovery considered. PMID:28051148

Compact microchannel system

DOEpatents

Griffiths, Stewart

2003-09-30

The present invention provides compact geometries for the layout of microchannel columns through the use of turns and straight channel segments. These compact geometries permit the use of long separation or reaction columns on a small microchannel substrate or, equivalently, permit columns of a fixed length to occupy a smaller substrate area. The new geometries are based in part on mathematical analyses that provide the minimum turn radius for which column performance in not degraded. In particular, we find that straight channel segments of sufficient length reduce the required minimum turn radius, enabling compact channel layout when turns and straight segments are combined. The compact geometries are obtained by using turns and straight segments in overlapped or nested arrangements to form pleated or coiled columns.

Influence of Piezosurgery on Bone Healing around Titanium Implants: A Histological Study in Rats.

PubMed

Sirolli, Marcelo; Mafra, Carlos Eduardo Secco; Santos, Rodrigo Albuquerque Basílio Dos; Saraiva, Luciana; Holzhausen, Marinella; César, João Batista

2016-01-01

The aim of this study was to evaluate histomorphometrically the influence of two techniques of dental implant site preparation on bone healing around titanium implants. Fifteen male Wistar rats (±300 g) were used in the study. Each tibia was randomly assigned to receive the implant site preparation either with a conventional drilling technique (control - DRILL group) or with a piezoelectric device (PIEZO group). The animals were sacrificed after 30 days and then the following histomorphometric parameters were evaluated (percentage) separately for cortical and cancellous regions: proportion of mineralized tissue (PMT) adjacent to implant threads (500 μm adjacent); bone area within the threads (BA) and bone-implant contact (BIC). The results demonstrated that there were no statistically significant differences between both groups for cancellous BIC (p>0.05) and cortical PMT (p>0.05). On the other hand, a higher percentage of BA was observed in the PIEZO group in the cortical (71.50±6.91 and 78.28±4.38 for DRILL and PIEZO groups, respectively; p<0.05) and cancellous regions (9.62±4.06 and 19.94±14.18 for DRILL and PIEZO groups, respectively; p<0.05). The piezosurgery also showed higher PMT values in the cancellous zone (9.35±5.54 and 18.72±13.21 for DRILL and PIEZO groups, respectively; p<0.05). However, the DRILL group presented better results for BIC in cortical region (80.42±10.88 and 70.25±16.93 for DRILL and PIEZO groups, respectively; p<0.05). In conclusion, for the implant site preparation, the piezosurgery was beneficial to bone healing rates in the cancellous bone region, while the drill technique produced better results in the cortical bone.

Magnesium-enriched hydroxyapatite as bone filler in an ameloblastoma mandibular defect

PubMed Central

Grigolato, Roberto; Pizzi, Natalia; Brotto, Maria C; Corrocher, Giovanni; Desando, Giovanna; Grigolo, Brunella

2015-01-01

The aim of this study was to evaluate the clinical performance of a magnesium-enriched hydroxyapatite biomaterial used as bone substitute in a case of mandibular ameloblastoma treated with conservative surgery. A 63 year old male patient was treated for an ameloblastoma in the anterior mandibular profile. After tissue excision, the bone defect was filled with a synthetic hydroxyapatite biomaterial enriched with magnesium ions, in order to promote bone tissue regeneration and obtain a good aesthetic result. Twenty-five months after surgery, due to ameloblastoma recurrence in an area adjacent to the previously treated one, the patient underwent to a further surgery. In that occasion the surgeon performed a biopsy in the initially treated area, in order to investigate the nature of the newly-formed tissue and to evaluate the bone regenerative potential of this biomaterial by clinical, radiographic and histological analyses. The clinical, radiographic and histological evaluations showed various characteristics of bone remodeling stage with an ongoing osteogenic formation and a good osteo-integration. In conclusion, magnesium-enriched hydroxyapatite used as bone substitute in a mandibular defect due to ameloblastoma excision showed an effective bone regeneration at 25 months follow-up, demonstrating an excellent biocompatibility and a high osteo-integration property. PMID:25784998

Localized accumulation of lead within and among bones from lead-dosed goats

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

Cretacci, Yan; Department of Environmental Health Sciences, School of Public Health, The University at Albany, P.O. Box 509, Albany, NY 12201-0509; Parsons, Patrick J., E-mail: pparsons@wadsworth.org

2010-01-15

The principal aim of this study was to gain a better understanding of where lead (Pb) accumulates and how it is distributed, within the bones of dosed goats. Adult goats were periodically dosed with Pb over a number of years for the primary purpose of producing blood pools containing endogenously bound Pb, for the New York State Blood Lead Proficiency Testing Program. Bone samples (e.g., primarily tibia, femur, humerus, and radius) were collected post-mortem from 11 animals and were analyzed for Pb content by acid digestion and electrothermal atomic absorption spectrometry (ETAAS or GFAAS). Average tibia Pb levels were foundmore » to correlate strongly with the cumulative Pb dose (r{sup 2}=0.81). However, the concentration of Pb in different bones and even within a small area of the same bone varied tremendously. Blood-rich trabecular (spongy) bone, such as the patella and calcaneus, were much more enriched in Pb than was cortical (compact) bone. In some dosed animals, the Pb concentration in the tibia was markedly higher at the proximal and distal ends of the bone compared to the mid-shaft. The implications of these findings with regard to the noninvasive measurement of lead in bone by XRF methods are discussed.« less

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

PubMed

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

2010-02-01

In order to validate whether bones' functional adaptation to mechanical loading is a local phenomenon, we randomly assigned 21 female C57BL/6 mice at 19 weeks of age to one of three equal numbered groups. All groups were treated with isoflurane anesthesia three times a week for 2 weeks (approximately 7 min/day). During each anaesthetic period, the right tibiae/fibulae in the DYNAMIC+STATIC group were subjected to a peak dynamic load of 11.5 N (40 cycles with 10-s intervals between cycles) superimposed upon a static "pre-load" of 2.0 N. This total load of 13.5 N engendered peak longitudinal strains of approximately 1400 microstrain on the medial surface of the tibia at a middle/proximal site. The right tibiae/fibulae in the STATIC group received the static "pre-load" alone while the NOLOAD group received no artificial loading. After 2 weeks, the animals were sacrificed and both tibiae, fibulae, femora, ulnae and radii analyzed by three-dimensional high-resolution (5 mum) micro-computed tomography (microCT). In the DYNAMIC+STATIC group, the proximal trabecular percent bone volume and cortical bone volume at the proximal and middle levels of the right tibiae as well as the cortical bone volume at the middle level of the right fibulae were markedly greater than the left. In contrast, the left bones in the DYNAMIC+STATIC group showed no differences compared to the left or right bones in the NOLOAD or STATIC group. These microCT data were confirmed by two-dimensional examination of fluorochrome labels in bone sections which showed the predominantly woven nature of the new bone formed in the loaded bones. We conclude that the adaptive response in both cortical and trabecular regions of bones subjected to short periods of dynamic loading, even when this response is sufficiently vigorous to stimulate woven bone formation, is confined to the loaded bones and does not involve changes in other bones that are adjacent, contra-lateral or remote to them. (c) 2009 Elsevier Inc

Legumain Regulates Differentiation Fate of Human Bone Marrow Stromal Cells and Is Altered in Postmenopausal Osteoporosis.

PubMed

Jafari, Abbas; Qanie, Diyako; Andersen, Thomas L; Zhang, Yuxi; Chen, Li; Postert, Benno; Parsons, Stuart; Ditzel, Nicholas; Khosla, Sundeep; Johansen, Harald Thidemann; Kjærsgaard-Andersen, Per; Delaisse, Jean-Marie; Abdallah, Basem M; Hesselson, Daniel; Solberg, Rigmor; Kassem, Moustapha

2017-02-14

Secreted factors are a key component of stem cell niche and their dysregulation compromises stem cell function. Legumain is a secreted cysteine protease involved in diverse biological processes. Here, we demonstrate that legumain regulates lineage commitment of human bone marrow stromal cells and that its expression level and cellular localization are altered in postmenopausal osteoporotic patients. As shown by genetic and pharmacological manipulation, legumain inhibited osteoblast (OB) differentiation and in vivo bone formation through degradation of the bone matrix protein fibronectin. In addition, genetic ablation or pharmacological inhibition of legumain activity led to precocious OB differentiation and increased vertebral mineralization in zebrafish. Finally, we show that localized increased expression of legumain in bone marrow adipocytes was inversely correlated with adjacent trabecular bone mass in a cohort of patients with postmenopausal osteoporosis. Our data suggest that altered proteolytic activity of legumain in the bone microenvironment contributes to decreased bone mass in postmenopausal osteoporosis. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Suppressive effect of compact bone-derived mesenchymal stem cells on chronic airway remodeling in murine model of asthma.

PubMed

Ogulur, Ismail; Gurhan, Gulben; Aksoy, Ayca; Duruksu, Gokhan; Inci, Cigdem; Filinte, Deniz; Kombak, Faruk Erdem; Karaoz, Erdal; Akkoc, Tunc

2014-05-01

New therapeutic strategies are needed in the treatment of asthma besides vaccines and pharmacotherapies. For the development of novel therapies, the use of mesenchymal stem cells (MSCs) is a promising approach in regenerative medicine. Delivery of compact bone (CB) derived MSCs to the injured lungs is an alternative treatment strategy for chronic asthma. In this study, we aimed to isolate highly enriched population of MSCs from mouse CB with regenerative capacity, and to investigate the impact of these cells in airway remodeling and inflammation in experimental ovalbumin-induced mouse model of chronic asthma. mCB-MSCs were isolated, characterized, labeled with GFP and then transferred into mice with chronic asthma developed by ovalbumin (OVA) provocation. Histopathological changes including basement membrane, epithelium, subepithelial smooth thickness and goblet cell hyperplasia, and MSCs migration to lung tissues were evaluated. These histopathological alterations were increased in ovalbumin-treated mice compared to PBS group (P<0.001). Intravenous administration of mCB-MSC significantly reduced these histopathological changes in both distal and proximal airways (P<0.001). We showed that GFP-labeled MSCs were located in the lungs of OVA group 2weeks after intravenous induction. mCB-MSCs also significantly promoted Treg response in ovalbumin-treated mice (OVA+MSC group) (P<0.037). Our studies revealed that mCB-MSCs migrated to lung tissue and suppressed histopathological changes in murine model of asthma. The results reported here provided evidence that mCB-MSCs may be an alternative strategy for the treatment of remodeling and inflammation associated with chronic asthma. Copyright © 2014 Elsevier B.V. All rights reserved.

Radiation-induced skin ulcer and rib fractures following percutaneous coronary intervention (PCI): A case of right back skin ulcer and adjacent rib fractures after single PCI.

PubMed

Yasukochi, Yumi; Nakahara, Takeshi; Koike, Akihiro; Ichikawa, Ryutaro; Koga, Tetsuya; Furue, Masutaka

2015-05-01

We experienced a 75-year-old male patient with a refractory and severely painful skin ulcer on the right back. He had suffered from ischemic heart disease and undergone percutaneous coronary intervention 5 months prior to the consultation with us. The characteristic clinical appearance, location of the lesion and his past medical history led us to the diagnosis of radiation-induced skin ulcer. Magnetic resonance imaging, computed tomography as well as bone scintigraphy showed fractures of the right back rib adjacent to the ulcer, which was thought to be attributable to bone damage due to X-ray radiation and/or persistent secondary inflammation of the chronic ulcer. In the published work, there are no other reports of bone fractures associated with radiation dermatitis after coronary interventional radiology. © 2015 Japanese Dermatological Association.

Variability of adjacency effects in sky reflectance measurements.

PubMed

Groetsch, Philipp M M; Gege, Peter; Simis, Stefan G H; Eleveld, Marieke A; Peters, Steef W M

2017-09-01

Sky reflectance R sky (λ) is used to correct in situ reflectance measurements in the remote detection of water color. We analyzed the directional and spectral variability in R sky (λ) due to adjacency effects against an atmospheric radiance model. The analysis is based on one year of semi-continuous R sky (λ) observations that were recorded in two azimuth directions. Adjacency effects contributed to R sky (λ) dependence on season and viewing angle and predominantly in the near-infrared (NIR). For our test area, adjacency effects spectrally resembled a generic vegetation spectrum. The adjacency effect was weakly dependent on the magnitude of Rayleigh- and aerosol-scattered radiance. The reflectance differed between viewing directions 5.4±6.3% for adjacency effects and 21.0±19.8% for Rayleigh- and aerosol-scattered R sky (λ) in the NIR. Under which conditions in situ water reflectance observations require dedicated correction for adjacency effects is discussed. We provide an open source implementation of our method to aid identification of such conditions.

Gelatine modified monetite as a bone substitute material: An in vitro assessment of bone biocompatibility.

PubMed

Kruppke, Benjamin; Farack, Jana; Wagner, Alena-Svenja; Beckmann, Sarah; Heinemann, Christiane; Glenske, Kristina; Rößler, Sina; Wiesmann, Hans-Peter; Wenisch, Sabine; Hanke, Thomas

2016-03-01

Calcium phosphate phases are increasingly used for bone tissue substitution, and the load bearing properties of these inherently brittle biomaterials are increased by inclusion of organic components. Monetite prepared using mineralization of gelatine pre-structured through phosphate leads to a significantly increased biaxial strength and indirect tensile strength compared to gelatine-free monetite. Besides the mechanical properties, degradation in physiological solutions and osteoblast and osteoclast cell response were investigated. Human bone marrow stromal cells (hBMSCs) showed considerably higher proliferation rates on the gelatine modified monetite than on polystyrene reference material in calcium-free as well as standard cell culture medium (α-MEM). Osteogenic differentiation on the material was comparable to polystyrene in both medium types. Osteoclast-like cells derived from monocytes were able to actively resorb the biomaterial. Osteoblastic differentiation and perhaps even more important the cellular resorption of the biomaterial indicate that it can be actively involved in the bone remodeling process. Thus the behavior of osteoblasts and osteoclasts as well as the adequate degradation and mechanical properties are strong indicators for bone biocompatibility, although in vivo studies are still required to prove this. New and unique? A low temperature precipitationprocessforcalcium anhydrous hydrogen phosphateallows for the first time to produce monolithic compact composites of monetite and gelatine. The composite is degradable and resorbable. To prove that, the question arises: what is bone biocompatibility? The reaction of both mayor cell types of bone represents this biocompatibility. Therefore, human bone marrow stromal cells were seeded revealing the materials pro-osteogenic properties. Monocyte cultivation, becoming recently focus of interest, revealed the capability of the biomaterial to be actively resorbed by derived osteoclast-like cells. Not new

Ectopic bone formation by marrow stromal osteoblast transplantation using poly(DL-lactic-co-glycolic acid) foams implanted into the rat mesentery

NASA Technical Reports Server (NTRS)

Ishaug-Riley, S. L.; Crane, G. M.; Gurlek, A.; Miller, M. J.; Yasko, A. W.; Yaszemski, M. J.; Mikos, A. G.; McIntire, L. V. (Principal Investigator)

1997-01-01

Porous biodegradable poly(DL-lactic-co-glycolic acid) foams were seeded with rat marrow stromal cells and implanted into the rat mesentery to investigate in vivo bone formation at an ectopic site. Cells were seeded at a density of 6.83 x 10(5) cells/cm2 onto polymer foams having pore sizes ranging from either 150 to 300 to 710 microns and cultured for 7 days in vitro prior to implantation. The polymer/cell constructs were harvested after 1, 7, 28, or 49 days in vivo and processed for histology and gel permeation chromatography. Visual observation of hematoxylin and eosin-stained sections and von Kossa-stained sections revealed the formation of mineralized bonelike tissue in the constructs within 7 days postimplantation. Ingrowth of vascular tissue was also found adjacent to the islands of bone, supplying the necessary metabolic requirements to the newly formed tissue. Mineralization and bone tissue formation were investigated by histomorphometry. The average penetration depth of mineralized tissue in the construct ranged from 190 +/- 50 microns for foams with 500-710-microns pores to 370 +/- 160 microns for foams with 150-300-microns pores after 49 days in vivo. The mineralized bone volume per surface area and total bone volume per surface area had maximal values of 0.28 +/- 0.21 mm (500-710-microns pore size, day 28) and 0.038 +/- 0.024 mm (150-300-microns, day 28), respectively. As much as 11% of the foam volume penetrated by bone tissue was filled with mineralized tissue. No significant trends over time were observed for any of the measured values (penetration depth, bone volume/surface area, or percent mineralized bone volume). These results suggest the feasibility of bone formation by osteoblast transplantation in an orthotopic site where not only bone formation from transplanted cells but also ingrowth from adjacent bone may occur.

Growth of the flat bones of the membranous neurocranium: a computational model.

PubMed

Garzón-Alvarado, Diego A; González, Andres; Gutiérrez, Maria Lucia

2013-12-01

This article assumes two stages in the formation of the bones in the calvaria, the first one takes into account the formation of the primary centers of ossification. This step counts on the differentiation from mesenchymal cells into osteoblasts. A molecular mechanism is used based on a system of reaction-diffusion between two antagonistic molecules, which are BMP2 and Noggin. To this effect we used equations whose behavior allows finding Turing patterns that determine the location of the primary centers. In the second step of the model we used a molecule that is expressed by osteoblasts, called Dxl5 and that is expressed from the osteoblasts of each flat bone. This molecule allows bone growth through its borders through cell differentiation adjacent to each bone of the skull. The model has been implemented numerically using the finite element method. The results allow us to observe a good approximation of the formation of flat bones of the membranous skull as well as the formation of fontanelles and sutures. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Osteonic organization of limb bones in mammals, including humans, and birds: a preliminary study.

PubMed

Castrogiovanni, Paola; Imbesi, Rosa; Fisichella, Marco; Mazzone, Venera

2011-01-01

As it is well known, bone tissue is characterized by a calcified extracellular matrix which makes this tissue suitable to support the body and protect the inner organs. Lamellar bone tissue is organized in lamellae, 3-7 microm in thickness, and arranged concentrically around vascular channels: the basic structure in this type of organization is called Haversian system or osteon and the diameter of osteons depends on the number of lamellae. Shape and regional density of osteons are related to the bone segment and the specific functional requirements to meet. Aim of this study is to correlate the compact bone tissue microstructure in various classes of mammals, including humans, and birds in order to find an adequate identification key. The results of our study show that in bone tissue samples from various classes of mammals, including humans, and birds the osteonic structure shows peculiar features, often depending on the rate of bone remodelling, different in different animal species. We conclude that a careful microscopic analysis of bone tissue and the characterization of distinctive osteonic features could give a major contribution to forensic medicine to obtain a more reliable recognition of bone findings.

Microtomographic imaging in the process of bone modeling and simulation

NASA Astrophysics Data System (ADS)

Mueller, Ralph

1999-09-01

Micro-computed tomography ((mu) CT) is an emerging technique to nondestructively image and quantify trabecular bone in three dimensions. Where the early implementations of (mu) CT focused more on technical aspects of the systems and required equipment not normally available to the general public, a more recent development emphasized practical aspects of micro- tomographic imaging. That system is based on a compact fan- beam type of tomograph, also referred to as desktop (mu) CT. Desk-top (mu) CT has been used extensively for the investigation of osteoporosis related health problems gaining new insight into the organization of trabecular bone and the influence of osteoporotic bone loss on bone architecture and the competence of bone. Osteoporosis is a condition characterized by excessive bone loss and deterioration in bone architecture. The reduced quality of bone increases the risk of fracture. Current imaging technologies do not allow accurate in vivo measurements of bone structure over several decades or the investigation of the local remodeling stimuli at the tissue level. Therefore, computer simulations and new experimental modeling procedures are necessary for determining the long-term effects of age, menopause, and osteoporosis on bone. Microstructural bone models allow us to study not only the effects of osteoporosis on the skeleton but also to assess and monitor the effectiveness of new treatment regimens. The basis for such approaches are realistic models of bone and a sound understanding of the underlying biological and mechanical processes in bone physiology. In this article, strategies for new approaches to bone modeling and simulation in the study and treatment of osteoporosis and age-related bone loss are presented. The focus is on the bioengineering and imaging aspects of osteoporosis research. With the introduction of desk-top (mu) CT, a new generation of imaging instruments has entered the arena allowing easy and relatively inexpensive access to

Insensitivity of compaction properties of brittle granules to size enlargement by roller compaction.

PubMed

Wu, Sy-Juen; Sun, Changquan 'Calvin'

2007-05-01

Pharmaceutical granules prepared by roller compaction often exhibit significant loss of tabletability, that is, reduction in tensile strength, when compared to virgin powder. This may be attributed to granule size enlargement for highly plastic materials, for example, microcrystalline cellulose. The sensitivity of powder compaction properties on granule size variations impacts the robustness of the dry granulation process. We hypothesize that such sensitivity of compaction properties on granule size is minimum for brittle materials because extensive fracture of brittle granules during compaction minimizes differences in initial granule size. We tested the hypothesis using three common brittle excipients. Results show that the fine (44-106 microm), medium (106-250 microm), and coarse (250-500 microm) granules exhibit essentially identical tabletability below a certain critical compaction pressure, 100, 140, and 100 MPa for spray-dried lactose monohydrate, anhydrous dibasic calcium phosphate, and mannitol, respectively. Above respective critical pressure, tabletability lines diverge with smaller granules exhibiting slightly higher tablet tensile strength at identical compaction conditions. Overall, tabletability of brittle granules is insensitive to granule size enlargement. The results provide a scientific basis to the common practice of incorporating brittle filler to a typical tablet formulation processed by roller compaction granulation. (c) 2007 Wiley-Liss, Inc. and the American Pharmacists Association.

Morphometric analysis - Cone beam computed tomography to predict bone quality and quantity.

PubMed

Hohlweg-Majert, B; Metzger, M C; Kummer, T; Schulze, D

2011-07-01

Modified quantitative computed tomography is a method used to predict bone quality and quantify the bone mass of the jaw. The aim of this study was to determine whether bone quantity or quality was detected by cone beam computed tomography (CBCT) combined with image analysis. MATERIALS AND PROCEDURES: Different measurements recorded on two phantoms (Siemens phantom, Comac phantom) were evaluated on images taken with the Somatom VolumeZoom (Siemens Medical Solutions, Erlangen, Germany) and the NewTom 9000 (NIM s.r.l., Verona, Italy) in order to calculate a calibration curve. The spatial relationships of six sample cylinders and the repositioning from four pig skull halves relative to adjacent defined anatomical structures were assessed by means of three-dimensional visualization software. The calibration curves for computer tomography (CT) and cone beam computer tomography (CBCT) using the Siemens phantom showed linear correlation in both modalities between the Hounsfield Units (HU) and bone morphology. A correction factor for CBCT was calculated. Exact information about the micromorphology of the bone cylinders was only available using of micro computer tomography. Cone-beam computer tomography is a suitable choice for analysing bone mass, but, it does not give any information about bone quality. 2010 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

Identification of proteinaceous material in the bone of the dinosaur Iguanodon.

PubMed

Embery, Graham; Milner, Angela C; Waddington, Rachel J; Hall, Rachel C; Langley, Martin S; Milan, Anna M

2003-01-01

This study has directed attention at the search for bone-related proteins in an extract of demineralized rib bone of the 120 mya Iguanodon. The inner compact bone was demineralized and the GuCl extract resolved into 11 fractions using anion exchange chromatography, which all contained silver-reactive proteins with various amino acid profiles. Two specific fractions, iv and xi, revealed characteristics typical of contemporary phosphoproteins and proteoglycans, respectively. Fraction iv, 43-57 kDa, contained a high ratio of aspartate and serine, although no phosphate was discernable. Fraction xi contained a band of 41-47 kDa and was rich in chondroitin sulphate and hyaluronan. In addition an early eluting fraction was immunoreactive with an antibody against osteocalcin. A cancellous bone fraction from the same bone sample was also analyzed using N-terminal sequencing and revealed potential similarities with cystatin. While we do not claim to have identified the presence of intact proteins, this study has value in demonstrating that extruded extracellular matrix is protected by its capacity to induce mineralization, which subsequently is important in conserving detectable protein products in ancient skeletal tissues.

47 CFR 101.1421 - Coordination of adjacent area MVDDS stations.

Code of Federal Regulations, 2010 CFR

2010-10-01

... SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Multichannel Video Distribution and Data Service Rules for... compatible with adjacent and co-channel operations in the adjacent areas on all its frequencies; and (2... adjacent and co-channel operations in adjacent areas. (b) Harmful interference to public safety stations...

Alteration of mineral crystallinity and collagen cross-linking of bones in osteopetrotic toothless (tl/tl) rats and their improvement after treatment with colony stimulating factor-1

NASA Technical Reports Server (NTRS)

Wojtowicz, A.; Dziedzic-Goclawska, A.; Kaminski, A.; Stachowicz, W.; Wojtowicz, K.; Marks, S. C. Jr; Yamauchi, M.

1997-01-01

A common feature of various types of mammalian osteopetroses is a marked increase in bone mass accompanied by spontaneous bone fractures. The toothless (tl/tl) rat osteopetrotic mutation is characterized by drastically reduced bone resorption due to a profound deficiency of osteoclasts and their precursors. An altered bone morphology has also been observed. The mutants cannot be cured by bone marrow transplantation, but skeletal defects are greatly reduced after treatment with colony stimulating factor 1 (CSF-1). The objectives of this study were to characterize mineral and collagen matrices in cancellous and compact bone isolated from long bones of 6-week-old normal littermates, tl/tl osteopetrotic mutants and mutants (tl/tl) treated with CSF-1. There were no differences in bone mineral content, but a significant decrease in the crystallinity of mineral evaluated by the method based on electron paramagnetic resonance spectrometry was observed in all bones of tl/tl mutants as compared to that of controls. Within the collagen matrix, slight decreases in the labile cross-links, but significant increases in the content of the stable cross-links, pyridinoline, and deoxypyridinoline, were observed in both cancellous and compact bone of osteopetrotic mutants. In tl/tl mutants treated with human recombinant CSF-1, the normalization of the crystallinity of bone mineral as well as collagen cross-links was found. Our results indicate that remodeling of bone matrix in tl/tl mutants is highly suppressed, but that after treatment with CSF-1, this activity recovers significantly. Taken together, these data provide further support for the hypothesis that CSF-1 is an essential factor for normal osteoclast differentiation and bone remodelling.

Guiding bone formation in a critical-sized defect and assessments.

PubMed

Jannetty, Joseph; Kolb, Eric; Boxberger, John; Deslauriers, Richard; Ganey, Timothy

2010-11-01

Development of alternatives to autologous bone has been served by many hypotheses and developments. Favorable properties of synthetic materials used currently in bone grafting support tissue differentiation without shielding capacity for integrated modeling. Ideally, new materials provide tissue compatibility and minimize patient morbidity and are attractive because of potential for in situ delivery, isothermal polymerization, porous structure, and nontoxic chemistry. For application in cranial bone, ability for materials to be laid adjacent to brain and offer postsurgical protection without neural risk is a critical asset. Kryptonite Bone Cement (KBC) meets the property criteria for cranial bone repair with regard to adhesive, conductive, and biologic transparency and US Food and Drug Administration approval for cranial bone void repair. To better delineate the morphology effective in cranial bone repair, a comparison was made between KBC and BoneSource, another material approved for the same indication. After Institutional Animal Care and Use Committee approval, the study assessed 24 rabbits, each with 2 separate cranial implants, to evaluate integration and absorption of the biomaterial at defined time points of 12, 18, 24, and 36 weeks. The 36-week assessment demonstrated near-complete resorption/integration of the BoneSource graft material. Bone was present within the biomaterial as well as independent of contact. The KBC was similarly integrated throughout the mass of the material, and new bone was in contact with the grafting material and also seen as separate islands of new bone. The bone demonstrated lamellar bone architecture with clear trabecular morphology. At higher magnification, the bone architecture can be clearly delineated, and comparison between the graft fillers is not obvious relative to the bone that has formed. Despite microscopic similarities, the most striking difference was maintenance of scaffold anatomy during bone regeneration

On-chip synthesis of fine-tuned bone-seeking hybrid nanoparticles.

PubMed

Hasani-Sadrabadi, Mohammad Mahdi; Dashtimoghadam, Erfan; Bahlakeh, Ghasem; Majedi, Fatemeh S; Keshvari, Hamid; Van Dersarl, Jules J; Bertsch, Arnaud; Panahifar, Arash; Renaud, Philippe; Tayebi, Lobat; Mahmoudi, Morteza; Jacob, Karl I

2015-01-01

Here we report a one-step approach for reproducible synthesis of finely tuned targeting multifunctional hybrid nanoparticles (HNPs). A microfluidic-assisted method was employed for controlled nanoprecipitation of bisphosphonate-conjugated poly(D,L-lactide-co-glycolide) chains, while coencapsulating superparamagnetic iron oxide nanoparticles and the anticancer drug Paclitaxel. Smaller and more compact HNPs with narrower size distribution and higher drug loading were obtained at microfluidic rapid mixing regimen compared with the conventional bulk method. The HNPs were shown to have a strong affinity for hydroxyapatite, as demonstrated in vitro bone-binding assay, which was further supported by molecular dynamics simulation results. In vivo proof of concept study verified the prolonged circulation of targeted microfluidic HNPs. Biodistribution as well as noninvasive bioimaging experiments showed high tumor localization and suppression of targeted HNPs to the bone metastatic tumor. The hybrid bone-targeting nanoparticles with adjustable characteristics can be considered as promising nanoplatforms for various theragnostic applications.

Drilling electrode for real-time measurement of electrical impedance in bone tissues.

PubMed

Dai, Yu; Xue, Yuan; Zhang, Jianxun

2014-03-01

In order to prevent possible damages to soft tissues, reliable monitoring methods are required to provide valuable information on the condition of the bone being cut. This paper describes the design of an electrical impedance sensing drill developed to estimate the relative position between the drill and the bone being drilled. The two-electrode method is applied to continuously measure the electrical impedance during a drill feeding movement: two copper wire brushes are used to conduct electricity in the rotating drill and then the drill is one electrode; a needle is inserted into the soft tissues adjacent to the bone being drilled and acts as another electrode. Considering that the recorded electrical impedance is correlated with the insertion depth of the drill, we theoretically calculate the electrode-tissue contact impedance and prove that the rate of impedance change varies considerably when the drill bit crosses the boundary between two different bone tissues. Therefore, the rate of impedance change is used to determine whether the tip of the drill is located in one of cortical bone, cancellous bone, and cortical bone near a boundary with soft tissue. In vitro experiments in porcine thoracic spines were performed to demonstrate the feasibility of the impedance sensing drill. The experimental results indicate that the drill, used with the proposed data-processing method, can provide accurate and reliable breakthrough detection in the bone-drilling process.

As solid as a rock-comparison of CE- and MPS-based analyses of the petrosal bone as a source of DNA for forensic identification of challenging cranial bones.

PubMed

Kulstein, Galina; Hadrys, Thorsten; Wiegand, Peter

2018-01-01

Short tandem repeat (STR) typing from skeletal remains can be a difficult task. Dependent on the environmental conditions of the provenance of the bones, DNA can be degraded and STR typing inhibited. Generally, dense and compact bones are known to preserve DNA better. Several studies already proved that femora and teeth have high DNA typing success rates. Unfortunately, these elements are not present in all cases involving skeletal remains. Processing partial or singular skeletal elements, it is favorable to select bone areas where DNA preservation is comparably higher. Especially, cranial bones are often accidentally discovered during criminal investigations. The cranial bone is composed of multiple parts. In this examination, we evaluated the potential of the petrous bone for human identification of skeletal remains in forensic case work. Material from different sections of eight unknown cranial bones and-where available-additionally other skeletal elements, collected at the DNA department of the Institute of Legal Medicine in Ulm, Germany, from 2010 to 2017, were processed with an optimized DNA extraction and STR typing strategy. The results highlight that STR typing from the petrous bones leads to reportable profiles in all individuals, even in cases where the analysis of the parietal bone failed. Moreover, the comparison of capillary electrophorese (CE) typing to massively parallel sequencing (MPS) analysis shows that MPS has the potential to analyze degraded human remains and is even capable to provide additional information about phenotype and ancestry of unknown individuals.

WNT16 Influences Bone Mineral Density, Cortical Bone Thickness, Bone Strength, and Osteoporotic Fracture Risk

PubMed Central

Eriksson, Joel; Paternoster, Lavinia; Yerges-Armstrong, Laura M.; Lehtimäki, Terho; Bergström, Ulrica; Kähönen, Mika; Leo, Paul J.; Raitakari, Olli; Laaksonen, Marika; Nicholson, Geoffrey C.; Viikari, Jorma; Ladouceur, Martin; Lyytikäinen, Leo-Pekka; Medina-Gomez, Carolina; Rivadeneira, Fernando; Prince, Richard L.; Sievanen, Harri; Leslie, William D.; Mellström, Dan; Eisman, John A.; Movérare-Skrtic, Sofia; Goltzman, David; Hanley, David A.; Jones, Graeme; St. Pourcain, Beate; Xiao, Yongjun; Timpson, Nicholas J.; Smith, George Davey; Reid, Ian R.; Ring, Susan M.; Sambrook, Philip N.; Karlsson, Magnus; Dennison, Elaine M.; Kemp, John P.; Danoy, Patrick; Sayers, Adrian; Wilson, Scott G.; Nethander, Maria; McCloskey, Eugene; Vandenput, Liesbeth; Eastell, Richard; Liu, Jeff; Spector, Tim; Mitchell, Braxton D.; Streeten, Elizabeth A.; Brommage, Robert; Pettersson-Kymmer, Ulrika; Brown, Matthew A.; Ohlsson, Claes; Richards, J. Brent; Lorentzon, Mattias

2012-01-01

We aimed to identify genetic variants associated with cortical bone thickness (CBT) and bone mineral density (BMD) by performing two separate genome-wide association study (GWAS) meta-analyses for CBT in 3 cohorts comprising 5,878 European subjects and for BMD in 5 cohorts comprising 5,672 individuals. We then assessed selected single-nucleotide polymorphisms (SNPs) for osteoporotic fracture in 2,023 cases and 3,740 controls. Association with CBT and forearm BMD was tested for ∼2.5 million SNPs in each cohort separately, and results were meta-analyzed using fixed effect meta-analysis. We identified a missense SNP (Thr>Ile; rs2707466) located in the WNT16 gene (7q31), associated with CBT (effect size of −0.11 standard deviations [SD] per C allele, P = 6.2×10−9). This SNP, as well as another nonsynonymous SNP rs2908004 (Gly>Arg), also had genome-wide significant association with forearm BMD (−0.14 SD per C allele, P = 2.3×10−12, and −0.16 SD per G allele, P = 1.2×10−15, respectively). Four genome-wide significant SNPs arising from BMD meta-analysis were tested for association with forearm fracture. SNP rs7776725 in FAM3C, a gene adjacent to WNT16, was associated with a genome-wide significant increased risk of forearm fracture (OR = 1.33, P = 7.3×10−9), with genome-wide suggestive signals from the two missense variants in WNT16 (rs2908004: OR = 1.22, P = 4.9×10−6 and rs2707466: OR = 1.22, P = 7.2×10−6). We next generated a homozygous mouse with targeted disruption of Wnt16. Female Wnt16−/− mice had 27% (P<0.001) thinner cortical bones at the femur midshaft, and bone strength measures were reduced between 43%–61% (6.5×10−13bone strength, and risk of fracture. PMID:22792071

Osteogenic potential of a chalcone in a critical-size defect in rat calvaria bone.

PubMed

Ortolan, Xana Raquel; Fenner, Bruna Proiss; Mezadri, Telmo José; Tames, David Rivero; Corrêa, Rogério; de Campos Buzzi, Fátima

2014-07-01

This study describes the bone formation stimulated by the application of a type of chalcone to critical-size defects in rat calvarial bone. Sixty female Wistar rats were divided into 6 groups of 10 animals per group: control (no treatment), vehicle (vaseline) and the chalcone (1-phenyl-3-(4-chlorophenyl)-2-propen-1-one) suspended in vaseline at 10%. A critical-size defect of 5 mm was prepared using a trephine in the calvarial bone, after which the treatment was applied, in a single dose, according to the experimental group. The samples were evaluated macroscopically using ImageJ software, and histologically 30 and 45 days after surgery. At 30 days after surgery, there was significant bone formation (p < 0.05) in the groups treated with chalcone, compared with the other groups. Many active osteoblasts were observed adjacent to the borders of the newly formed bone tissue. 45 days after surgery in the chalcone group, the surgical defects showed complete bone closure. The results of this study suggest that chalcone has significant potential to induce the formation of new bone. Copyright © 2013 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

Application of Ultrasonic Bone Curette in Endoscopic Endonasal Skull Base Surgery: Technical Note

PubMed Central

Rastelli, Milton M.; Pinheiro-Neto, Carlos D.; Fernandez-Miranda, Juan C.; Wang, Eric W.; Snyderman, Carl H.; Gardner, Paul A.

2014-01-01

Background Endoscopic endonasal surgery (EES) of the skull base often requires extensive bone work in proximity to critical neurovascular structures. Objective To demonstrate the application of an ultrasonic bone curette during EES. Methods Ten patients with skull base lesions underwent EES from September 2011 to April 2012 at the University of Pittsburgh Medical Center. Most of the bone work was done with high-speed drill and rongeurs. The ultrasonic curette was used to remove specific structures. Results All the patients were submitted to fully endoscopic endonasal procedures and had critical bony structures removed with the ultrasonic bone curette. Two patients with degenerative spine diseases underwent odontoid process removal. Five patients with clival and petroclival tumors underwent posterior clinoid removal. Two patients with anterior fossa tumors underwent crista galli removal. One patient underwent unilateral optic nerve decompression. No mechanical or heat injury resulted from the ultrasonic curette. The surrounding neurovascular structures and soft tissue were preserved in all cases. Conclusion In selected EES, the ultrasonic bone curette was successfully used to remove loose pieces of bone in narrow corridors, adjacent to neurovascular structures, and it has advantages to high-speed drills in these specific situations. PMID:24719795

Optimizing Soft Tissue Management and Spacer Design in Segmental Bone Defects

DTIC Science & Technology

2014-10-01

the time of the “Pre-Procedure”. Autogenous Cancellous Bone Graft (ACBG harvested from the sternum at the time of the treatment surgery is used as...will receive more specialized training and orientation to microCT analysis, both on a theoretical and practical level. He will work with raw CT...adjacent to the PMMA) composed of mononuclear cells and exhibited extensive, diffuse fibrous connective tissue.  Performed histology on goat autogenous

The Tarsometatarsus of the Ostrich Struthio camelus: Anatomy, Bone Densities, and Structural Mechanics.

PubMed

Gilbert, Meagan M; Snively, Eric; Cotton, John

2016-01-01

The ostrich Struthio camelus reaches the highest speeds of any extant biped, and has been an extraordinary subject for studies of soft-tissue anatomy and dynamics of locomotion. An elongate tarsometatarsus in adult ostriches contributes to their speed. The internal osteology of the tarsometatarsus, and its mechanical response to forces of running, are potentially revealing about ostrich foot function. Computed tomography (CT) reveals anatomy and bone densities in tarsometatarsi of an adult and a young juvenile ostrich. A finite element (FE) model for the adult was constructed with properties of compact and cancellous bone where these respective tissues predominate in the original specimen. The model was subjected to a quasi-static analysis under the midstance ground reaction and muscular forces of a fast run. Anatomy-Metatarsals are divided proximally and distally and unify around a single internal cavity in most adult tarsometatarsus shafts, but the juvenile retains an internal three-part division of metatarsals throughout the element. The juvenile has a sparsely ossified hypotarsus for insertion of the m. fibularis longus, as part of a proximally separate third metatarsal. Bone is denser in all regions of the adult tarsometatarsus, with cancellous bone concentrated at proximal and distal articulations, and highly dense compact bone throughout the shaft. Biomechanics-FE simulations show stress and strain are much greater at midshaft than at force applications, suggesting that shaft bending is the most important stressor of the tarsometatarsus. Contraction of digital flexors, inducing a posterior force at the TMT distal condyles, likely reduces buildup of tensile stresses in the bone by inducing compression at these locations, and counteracts bending loads. Safety factors are high for von Mises stress, consistent with faster running speeds known for ostriches. High safety factors suggest that bone densities and anatomy of the ostrich tarsometatarsus confer strength

The Tarsometatarsus of the Ostrich Struthio camelus: Anatomy, Bone Densities, and Structural Mechanics

PubMed Central

Gilbert, Meagan M.; Snively, Eric; Cotton, John

2016-01-01

Background The ostrich Struthio camelus reaches the highest speeds of any extant biped, and has been an extraordinary subject for studies of soft-tissue anatomy and dynamics of locomotion. An elongate tarsometatarsus in adult ostriches contributes to their speed. The internal osteology of the tarsometatarsus, and its mechanical response to forces of running, are potentially revealing about ostrich foot function. Methods/Principal Findings Computed tomography (CT) reveals anatomy and bone densities in tarsometatarsi of an adult and a young juvenile ostrich. A finite element (FE) model for the adult was constructed with properties of compact and cancellous bone where these respective tissues predominate in the original specimen. The model was subjected to a quasi-static analysis under the midstance ground reaction and muscular forces of a fast run. Anatomy–Metatarsals are divided proximally and distally and unify around a single internal cavity in most adult tarsometatarsus shafts, but the juvenile retains an internal three-part division of metatarsals throughout the element. The juvenile has a sparsely ossified hypotarsus for insertion of the m. fibularis longus, as part of a proximally separate third metatarsal. Bone is denser in all regions of the adult tarsometatarsus, with cancellous bone concentrated at proximal and distal articulations, and highly dense compact bone throughout the shaft. Biomechanics–FE simulations show stress and strain are much greater at midshaft than at force applications, suggesting that shaft bending is the most important stressor of the tarsometatarsus. Contraction of digital flexors, inducing a posterior force at the TMT distal condyles, likely reduces buildup of tensile stresses in the bone by inducing compression at these locations, and counteracts bending loads. Safety factors are high for von Mises stress, consistent with faster running speeds known for ostriches. Conclusions/Significance High safety factors suggest that bone

COMPACT E+A GALAXIES AS A PROGENITOR OF MASSIVE COMPACT QUIESCENT GALAXIES AT 0.2 < z < 0.8

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

Zahid, H. Jabran; Hochmuth, Nicholas Baeza; Geller, Margaret J.

We search the Sloan Digital Sky Survey and the Baryon Oscillation Sky Survey to identify ∼5500 massive compact quiescent galaxy candidates at 0.2 < z < 0.8. We robustly classify a subsample of 438 E+A galaxies based on their spectral properties and make this catalog publicly available. We examine sizes, stellar population ages, and kinematics of galaxies in the sample and show that the physical properties of compact E+A galaxies suggest that they are a progenitor of massive compact quiescent galaxies. Thus, two classes of objects—compact E+A and compact quiescent galaxies—may be linked by a common formation scenario. The typicalmore » stellar population age of compact E+A galaxies is <1 Gyr. The existence of compact E+A galaxies with young stellar populations at 0.2 < z < 0.8 means that some compact quiescent galaxies first appear at intermediate redshifts. We derive a lower limit for the number density of compact E+A galaxies. Assuming passive evolution, we convert this number density into an appearance rate of new compact quiescent galaxies at 0.2 < z < 0.8. The lower limit number density of compact quiescent galaxies that may appear at z < 0.8 is comparable to the lower limit of the total number density of compact quiescent galaxies at these intermediate redshifts. Thus, a substantial fraction of the z < 0.8 massive compact quiescent galaxy population may descend from compact E+A galaxies at intermediate redshifts.« less

33 CFR 80.1395 - Puget Sound and adjacent waters.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Puget Sound and adjacent waters... INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Thirteenth District § 80.1395 Puget Sound and adjacent waters. The 72 COLREGS shall apply on all waters of Puget Sound and adjacent waters, including Lake Union...

33 CFR 80.1395 - Puget Sound and adjacent waters.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Puget Sound and adjacent waters... INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Thirteenth District § 80.1395 Puget Sound and adjacent waters. The 72 COLREGS shall apply on all waters of Puget Sound and adjacent waters, including Lake Union...

33 CFR 80.1395 - Puget Sound and adjacent waters.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Puget Sound and adjacent waters... INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Thirteenth District § 80.1395 Puget Sound and adjacent waters. The 72 COLREGS shall apply on all waters of Puget Sound and adjacent waters, including Lake Union...

33 CFR 80.1395 - Puget Sound and adjacent waters.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Puget Sound and adjacent waters... INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Thirteenth District § 80.1395 Puget Sound and adjacent waters. The 72 COLREGS shall apply on all waters of Puget Sound and adjacent waters, including Lake Union...

33 CFR 80.1395 - Puget Sound and adjacent waters.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Puget Sound and adjacent waters... INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Thirteenth District § 80.1395 Puget Sound and adjacent waters. The 72 COLREGS shall apply on all waters of Puget Sound and adjacent waters, including Lake Union...

Comparison of titanium elastic intramedullary nailing versus injection of bone marrow in treatment of simple bone cysts in children: a retrospective study.

PubMed

Li, Wenchao; Xu, Ruijiang; Du, Minghua; Chen, Hui

2016-08-15

Simple bone cysts are common benign lytic bone lesions in children. The main goals of treatment for bone cysts are to prevent pathological fractures, support the healing process, and prevent recurrence. This retrospective study compared fixation with titanium elastic intramedullary nailing (TEN) versus aspiration and injection of autogenous bone marrow (ABM) for the treatment of simple bone cysts in children. Forty-six patients (mean follow-up, 62 months; range, 34-71 months) who presented with bone cysts (30 in the humerus, 16 in the femur) from January 2006 to December 2012 were retrospectively evaluated. Patients were treated with either TEN or ABM injection. Radiographs were evaluated according to previously established criteria. Clinical evaluations of pain, infection, additional fractures, and range of motion were performed. After treatment, all patients were pain-free and had normal range of motion in adjacent joints. In the ABM group, 14 (60.9 %) bone cysts completely healed, six (26.1 %) healed with small residuals after two injections, and three (13.0 %) recurred. In the TEN group, 16 (69.6 %) bone cysts completely healed, four (17.4 %) healed with small residuals, and three (13.0 %) recurred. There were no significant differences in radiographic outcomes between groups at the final follow-up (P > 0.05). Three patients developed skin irritation as a result of the nail ends. Additional fractures occurred in four patients who underwent ABM injection and in two patients who underwent TEN. No significant associations were found between pathological fractures and cyst activity, location, or treatment outcomes in the patients studied. Both TEN and ABM injection are safe and effective treatment for bone cysts. ABM injection promotes osteogenic differentiation of bone marrow stromal cells; multiple injections can reduce the likelihood of recurrence. TEN stabilizes the affected bone and thus allows early limb mobilization. It also reduces pressure in

Cryopreserved embryo transfer: adjacent or non-adjacent to failed fresh long GnRH-agonist protocol IVF cycle.

PubMed

Volodarsky-Perel, Alexander; Eldar-Geva, Talia; Holzer, Hananel E G; Schonberger, Oshrat; Reichman, Orna; Gal, Michael

2017-03-01

The optimal time to perform cryopreserved embryo transfer (CET) after a failed oocyte retrieval-embryo transfer (OR-ET) cycle is unknown. Similar clinical pregnancy rates were recently reported in immediate and delayed CET, performed after failed fresh OR-ET, in cycles with the gonadotrophin-releasing hormone (GnRH) antagonist protocol. This study compared outcomes of CET performed adjacently (<50 days, n = 67) and non-adjacently (≥50 to 120 days, n = 62) to the last OR-day of cycles with the GnRH agonist down-regulation protocol. Additional inclusion criteria were patients' age 20-38 years, the transfer of only 1-2 cryopreserved embryos, one treatment cycle per patient and artificial preparation for CET. Significantly higher implantation, clinical pregnancy and live birth rates were found in the non-adjacent group than in the adjacent group: 30.5% versus 11.3% (P = 0.001), 41.9% versus 17.9% (P = 0.003) and 32.3% versus 13.4% (P = 0.01), respectively. These results support the postponement of CET after a failed OR-ET for at least one menstrual cycle, when a preceding long GnRH-agonist protocol is used. Copyright © 2016 Reproductive Healthcare Ltd. Published by Elsevier Ltd. All rights reserved.

Evaluation of Bone Atrophy After Treatment of Forearm Fracture Using Nonlinear Finite Element Analysis: A Comparative Study of Locking Plates and Conventional Plates.

PubMed

Matsuura, Yusuke; Rokkaku, Tomoyuki; Suzuki, Takane; Thoreson, Andrew Ryan; An, Kai-Nan; Kuniyoshi, Kazuki

2017-08-01

Forearm diaphysis fractures are usually managed by open reduction internal fixation. Recently, locking plates have been used for treatment. In the long-term period after surgery, some patients present with bone atrophy adjacent to the plate. However, a comparison of locking and conventional plates as a cause of atrophy has not been reported. The aim of this study was to investigate long-term bone atrophy associated with use of locking and conventional plates for forearm fracture treatment. In this study we included 15 patients with forearm fracture managed by either locking or conventional plates and with more than 5 years of follow-up. Computed tomographic imaging of both forearms was performed to assess bone thickness and local bone mineral density and to predict bone strength without plate reinforcement based on finite element analysis. Mean patient age at surgery was 48.0 years. Eight patients underwent reduction with fixed locking plates and were followed up for a mean of 79.5 months; the remaining 7 patients were treated with conventional plates and were followed up for a mean of 105.0 months. Compared with the conventional plate group, the locking plate group had the same fractured limb-contralateral limb ratio of cortex bone thickness, but had significantly lower ratios of mineral density adjacent to the plate and adjusted bone strength. This study demonstrated bone atrophy after locking plate fixation for forearm fractures. Treatment plans for forearm fracture should take into consideration the impact of bone atrophy long after plate fixation. Therapeutic IV. Copyright © 2017 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

On the Nature of Expansion of Paget’s Disease of Bone

DTIC Science & Technology

2012-10-01

signaling pathway. Gene expression normalized to normal adjacent bone samples. 5 Global expression analysis revealed genes downstream of the Hedgehog ... Hedgehog (Hh) signaling pathway (Figure 5). Again, as in the TLR signaling pathway, specific elements of the Hh signaling pathway showed increased...mutations upregulated expression of genes in the Hedgehog signaling pathway. 7. Discovery that an osteoblastic cell line (PSV10) derived from a PDB

SEM corrosion-casts study of the microcirculation of the flat bones in the rat.

PubMed

Pannarale, L; Morini, S; D'Ubaldo, E; Gaudio, E; Marinozzi, G

1997-04-01

Little is known about the organization of microcirculation in flat bones in comparison with long bones. This study, therefore, helps us to determine the design of this vascular system in flat bones in relation to their structure and function. The organization of microvasculature in parietal, scapula, and ileum bones of 15 young sexually mature rats, aged 6-7 weeks, was studied by light and scanning electron microscopy (SEM) from vascular corrosion cast (vcc), a resin-cast obtained material. Our observations show that the pattern of the microcirculation in flat bones is different in the thick and thin parts of such bones. Where the bone is thinner than 0.4 mm, only periosteal and dural network exist. Larger vessels which do not form a real network connect the two tables of the bones in these regions. In thicker areas, the organization of the microvasculature is similar to that in long bones, with distinct periosteal, cortical and bone marrow networks. Moreover, in different bones, outer networks show slightly different characteristics according to the different adjacent structures (dura mater, muscles etc.). Different types of vessels were recognized by comparing their different diameter, course and endothelial imprints. The microvascular patterns of the flat bones are strongly influenced by the bone thickness. The different microvascular systems can interact both with the bone modelling and remodeling and with the variable metabolic needs, modifying the microvascular pattern and the blood flow. This is even more important in view of the reciprocal influence of the different networks within the same bone.

Fast particles in a steady-state compact FNS and compact ST reactor

NASA Astrophysics Data System (ADS)

Gryaznevich, M. P.; Nicolai, A.; Buxton, P.

2014-10-01

This paper presents results of studies of fast particles (ions and alpha particles) in a steady-state compact fusion neutron source (CFNS) and a compact spherical tokamak (ST) reactor with Monte-Carlo and Fokker-Planck codes. Full-orbit simulations of fast particle physics indicate that a compact high field ST can be optimized for energy production by a reduction of the necessary (for the alpha containment) plasma current compared with predictions made using simple analytic expressions, or using guiding centre approximation in a numerical code. Alpha particle losses may result in significant heating and erosion of the first wall, so such losses for an ST pilot plant have been calculated and total and peak wall loads dependence on the plasma current has been studied. The problem of dilution has been investigated and results for compact and big size devices are compared.

CALCIUM-47 IN THE STUDY OF BONE PHYSIOLOGY AND PATHOLOGY

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

Guerin, R.A.

1962-06-01

The use of Ca/sup 45/, Ca/sup 47/, Ga/sup 67/, and Sr/sup 85/ in the study of Ca metabolism of bone in human subjects is discussed. Ca/sup 47/ is considered to be most suitable because of its short half-life ( approximates 5 days) and high specific activity (10 mc/mg for Ca/sup 47/ Cl/sub 2/). Studies were conducted in 28 patients injected intravenously with Ca/sup 47/; uptake in various bones was followed by external scintillometry for periods up to 11 days later. In healthy subjects the distribution of activity was symmetrical, with highest uptake in sternum and manubrium and lower uptake inmore » cranium (particularly the occipital region), clavicle, and iliac crest. Epiphyses of the long bones showed less avidity for Ca/sup 47/, that in tibia being highest. Sternum fixed 2 to 21/2 more Ca/sup 47/ than the upper tibial epiphysis. This indicates that in the normal adult more Ca is taken up by spongy than compact bone. The Ca/sup 47/ content of bone increased rapidly, reaching a plateau by the 5th or 6th day in most bones and by the 10th day in some, such as clavicle. Studies in pathologic cases showed the very high, but transient, uptake by callus in fractures and and uptake in Paget's disease of bone that was 3 times normal. Higher than normal uptake was also noted in bone lesions in lymphogranulomatosis, where osteogenesis compensating for increased bone destruction could be detected. Pathologic states could also be detected by following the disappearance of Ca/sup 47/ from plasma, it being delayed by hypercalcemia associated with multiple cancer metastases in bone or accelerated by hypocalcemia, such as in Paget's disease. The rate of urinary excretion of radioactivity was also of diagnostic value. (H.H.D.)« less

Mechanical evaluation of the SLM fabricated, stiffness-matched, mandibular bone fixation plates

NASA Astrophysics Data System (ADS)

Jahadakbar, Ahmadreza; Shayesteh Moghaddam, Narges; Amerinatanzi, Amirhesam; Dean, David; Elahinia, Mohammad

2018-03-01

The standard of the care for the treatment of mandibular segmental defects is the use of Ti-6Al-4V bone fixation plates and screws to immobilize the grafted bone and the host mandible. While Ti-6Al-4V bone fixation plates provide strong immobilization during the healing period, they may disturb the stress distribution in the repaired mandible. The highly stiff Ti-6Al-4V fixation carries a great portion of the load which was previously borne by the mandible, and stress shielding may occur on the surrounding cortical bone. Based on the bone remodeling theory, stress shielding causes bone resorption in the effected region and may eventually lead to the failure of the surgical reconstruction. To address this issue, we have developed a new generation of the patient-specific, porous NiTi bone fixation plates which benefit from stiffness-matching of the adjacent bone. Using the CT scan data of the patient's defective mandible, the geometry for the required bone fixation plates is designed and the stiffness of the surrounding regions is measured. By introducing specific level and type of porosity to the bone fixation plate, its stiffness can be tuned. Finite Element simulations has verified the reduced level of stress shielding on the reconstructed mandible, in case of using the proposed bone fixation plates. Selective Lase Sintering has been used for fabrication of the porous NiTi bone fixation plates with six different levels of stiffness. Finite element simulations, and mechanical tests have been done to verify the performance of the fabricated parts resulting from our design and fabrication method.

Moderate chronic kidney disease impairs bone quality in C57Bl/6J mice.

PubMed

Heveran, Chelsea M; Ortega, Alicia M; Cureton, Andrew; Clark, Ryan; Livingston, Eric W; Bateman, Ted A; Levi, Moshe; King, Karen B; Ferguson, Virginia L

2016-05-01

Chronic kidney disease (CKD) increases bone fracture risk. While the causes of bone fragility in CKD are not clear, the disrupted mineral homeostasis inherent to CKD may cause material quality changes to bone tissue. In this study, 11-week-old male C57Bl/6J mice underwent either 5/6th nephrectomy (5/6 Nx) or sham surgeries. Mice were fed a normal chow diet and euthanized 11weeks post-surgery. Moderate CKD with high bone turnover was established in the 5/6 Nx group as determined through serum chemistry and bone gene expression assays. We compared nanoindentation modulus and mineral volume fraction (assessed through quantitative backscattered scanning electron microscopy) at matched sites in arrays placed on the cortical bone of the tibia mid-diaphysis. Trabecular and cortical bone microarchitecture and whole bone strength were also evaluated. We found that moderate CKD minimally affected bone microarchitecture and did not influence whole bone strength. Meanwhile, bone material quality decreased with CKD; a pattern of altered tissue maturation was observed with 5/6 Nx whereby the newest 60μm of bone tissue adjacent to the periosteal surface had lower indentation modulus and mineral volume fraction than more interior, older bone. The variance of modulus and mineral volume fraction was also altered following 5/6 Nx, implying that tissue-scale heterogeneity may be negatively affected by CKD. The observed lower bone material quality may play a role in the decreased fracture resistance that is clinically associated with human CKD. Copyright © 2016 Elsevier Inc. All rights reserved.

Moderate Chronic Kidney Disease Impairs Bone Quality in C57Bl/6J Mice

PubMed Central

Heveran, Chelsea M.; Ortega, Alicia M.; Cureton, Andrew; Clark, Ryan; Livingston, Eric; Bateman, Ted; Levi, Moshe; King, Karen B.; Ferguson, Virginia L.

2016-01-01

Chronic kidney disease (CKD) increases bone fracture risk. While the causes of bone fragility in CKD are not clear, the disrupted mineral homeostasis inherent to CKD may cause material quality changes to bone tissue. In this study, 11-week old male C57Bl/6J mice underwent either 5/6th nephrectomy (5/6 Nx) or sham procedures. Mice were fed a normal chow diet and euthanized 11 weeks post-surgery. Moderate CKD with high bone turnover was established in the 5/6 Nx group as determined through serum chemistry and bone gene expression assays. We compared nanoindentation modulus and mineral volume fraction (assessed through quantitative backscattered scanning electron microscopy) at matched sites in arrays placed on the cortical bone of the tibia mid-diaphysis. Trabecular and cortical bone microarchitecture (μCT) and whole bone strength were also evaluated. We found that moderate CKD minimally affected bone microarchitecture and did not influence whole bone strength. Meanwhile, bone material quality decreased with CKD; a pattern of altered tissue maturation was observed with 5/6 Nx whereby the newest 60 micrometers of bone tissue adjacent to the periosteal surface had lower indentation modulus and mineral volume fraction than more interior, older bone. The variance of modulus and mineral volume fraction were also altered following 5/6 Nx, implying that tissue-scale heterogeneity may be negatively affected by CKD. The observed lower bone material quality may play a role in the decreased fracture resistance that is clinically associated with human CKD. PMID:26860048

Assessing bone volume for orthodontic miniplate fixation below the maxillary frontal process.

PubMed

Präger, T M; Brochhagen, H G; Mischkowski, R; Jost-Brinkmann, P-G; Müller-Hartwich, R

2014-09-01

The maxillary bone below the frontal process is used for orthodontic anchorage; indications have included skeletally anchored protraction of the maxilla for treating Class III malocclusions or the intrusion of teeth in patients with a deep bite. This study was conducted to assess the condition of bone before cortically implanting miniplates in that area of the maxilla. A total of 51 thin-sliced computed tomography scans of 51 fully-dentate adult patients (mean age 24.0 ± 8.1 years; 27 men and 24 women) obtained prior to third-molar osteotomy were evaluated. Study parameters included total bone thickness, thickness of the facial cortical plate, and width of the nasal maxillary buttress. All these parameters were measured at different vertical levels. The bone volume adjacent to the piriform aperture was most pronounced at the basal level and decreased progressively toward more cranial levels. The basal bone structure had a mean total thickness of 7.8 mm, facial cortical plate thickness of 1.9 mm, and nasal maxillary buttress width of 9.2 mm. At 16 mm cranial to the aperture base, these values fell to 5.6 mm, 1.3 mm, and 5.8 mm, respectively. These bone measurements suggest that screws 7 mm in length can be inserted at the base level of the piriform aperture and screws 5 mm long at the cranial end of the bone.

Socket preservation using bovine bone mineral and collagen membrane: a randomized controlled clinical trial with histologic analysis.

PubMed

Cardaropoli, Daniele; Tamagnone, Lorenzo; Roffredo, Alessandro; Gaveglio, Lorena; Cardaropoli, Giuseppe

2012-08-01

After tooth extraction, varying amounts of bone resorption occur because of qualitative and quantitative changes at the edentulous site of the alveolar process. The aims of this randomized controlled clinical trial were (1) to compare the postextraction changes in residual ridge dimensions during spontaneous healing with those during socket preservation, (2) to analyze the histologic and histomorphometric aspects of the grafted sockets, and (3) to compare probing procket depth (PPD) and clinical attachment level (CAL) changes at teeth adjacent to extraction sites. Forty-eight teeth were extracted from 41 patients referred for extraction of 1 or more maxillary or mandibular premolars or molars. The edentulous sites were randomly assigned to the control (EXT, extraction alone) or experimental groups (SP, extraction and socket preservation). In the SP group, the sockets were filled with bovine bone mineral and covered with porcine collagen membrane. At baseline and after 4 months, PPD, gingival recession (REC), and CAL were measured at teeth adjacent to the edentulous sites. The changes in ridge dimensions from baseline to 4 months were assessed on dental casts. At 4 months, bone was harvested from the grafted areas in the SP group and the edentulous areas in the EXT group. PPD, REC, and CAL were comparable between groups. However, from baseline to 4 months, the SP group showed significantly less reduction in ridge width (1.04 ± 1.08 mm vs 4.48 ± 0.65 mm, P < .001) and height (0.46 ± 0.46 mm vs 1.54 ± 0.33 mm, P < .001). Histologically, the grafted sockets exhibited various stages of bone maturation and formation without inflammatory responses. No significant difference in the mineralized and nonmineralized fractions was noted between the groups. Socket preservation using bovine bone mineral and porcine collagen membrane considerably limits the amount of horizontal and vertical bone resorption when compared with extraction alone.

Optimal design of compact and connected nature reserves for multiple species.

PubMed

Wang, Yicheng; Önal, Hayri

2016-04-01

When designing a conservation reserve system for multiple species, spatial attributes of the reserves must be taken into account at species level. The existing optimal reserve design literature considers either one spatial attribute or when multiple attributes are considered the analysis is restricted only to one species. We built a linear integer programing model that incorporates compactness and connectivity of the landscape reserved for multiple species. The model identifies multiple reserves that each serve a subset of target species with a specified coverage probability threshold to ensure the species' long-term survival in the reserve, and each target species is covered (protected) with another probability threshold at the reserve system level. We modeled compactness by minimizing the total distance between selected sites and central sites, and we modeled connectivity of a selected site to its designated central site by selecting at least one of its adjacent sites that has a nearer distance to the central site. We considered structural distance and functional distances that incorporated site quality between sites. We tested the model using randomly generated data on 2 species, one ground species that required structural connectivity and the other an avian species that required functional connectivity. We applied the model to 10 bird species listed as endangered by the state of Illinois (U.S.A.). Spatial coherence and selection cost of the reserves differed substantially depending on the weights assigned to these 2 criteria. The model can be used to design a reserve system for multiple species, especially species whose habitats are far apart in which case multiple disjunct but compact and connected reserves are advantageous. The model can be modified to increase or decrease the distance between reserves to reduce or promote population connectivity. © 2015 Society for Conservation Biology.

Depth measurements of drilled holes in bone by laser triangulation for the field of oral implantology

NASA Astrophysics Data System (ADS)

Quest, D.; Gayer, C.; Hering, P.

2012-01-01

Laser osteotomy is one possible method of preparing beds for dental implants in the human jaw. A major problem in using this contactless treatment modality is the lack of haptic feedback to control the depth while drilling the implant bed. A contactless measurement system called laser triangulation is presented as a new procedure to overcome this problem. Together with a tomographic picture the actual position of the laser ablation in the bone can be calculated. Furthermore, the laser response is sufficiently fast as to pose little risk to surrounding sensitive areas such as nerves and blood vessels. In the jaw two different bone structures exist, namely the cancellous bone and the compact bone. Samples of both bone structures were examined with test drillings performed either by laser osteotomy or by a conventional rotating drilling tool. The depth of these holes was measured using laser triangulation. The results and the setup are reported in this study.

A review of recent advances in the assessment of bone porosity, permeability, and interstitial fluid flow

PubMed Central

Cardoso, Luis; Fritton, Susannah P.; Gailani, Gaffar; Benalla, Mohammed; Cowin, Stephen C.

2012-01-01

This contribution reviews recent research performed to assess the porosity and permeability of bone tissue with the objective of understanding interstitial fluid movement. Bone tissue mechanotransduction is considered to occur due to the passage of interstitial pore fluid adjacent to dendritic cell structures in the lacunar-canalicular porosity. The movement of interstitial fluid is also necessary for the nutrition of osteocytes. This review will focus on four topics related to improved assessment of bone interstitial fluid flow. First, the advantages and limitations of imaging technologies to visualize bone porosities and architecture at several length scales are summarized. Second, recent efforts to measure the vascular porosity and lacunar-canalicular microarchitecture are discussed. Third, studies associated with the measurement and estimation of the fluid pressure and permeability in the vascular and lacunar-canalicular domains are summarized. Fourth, the development of recent models to represent the interchange of fluids between the bone porosities is described. PMID:23174418

Imaging of Alkaline Phosphatase Activity in Bone Tissue

PubMed Central

Gade, Terence P.; Motley, Matthew W.; Beattie, Bradley J.; Bhakta, Roshni; Boskey, Adele L.; Koutcher, Jason A.; Mayer-Kuckuk, Philipp

2011-01-01

The purpose of this study was to develop a paradigm for quantitative molecular imaging of bone cell activity. We hypothesized the feasibility of non-invasive imaging of the osteoblast enzyme alkaline phosphatase (ALP) using a small imaging molecule in combination with 19Flourine magnetic resonance spectroscopic imaging (19FMRSI). 6, 8-difluoro-4-methylumbelliferyl phosphate (DiFMUP), a fluorinated ALP substrate that is activatable to a fluorescent hydrolysis product was utilized as a prototype small imaging molecule. The molecular structure of DiFMUP includes two Fluorine atoms adjacent to a phosphate group allowing it and its hydrolysis product to be distinguished using 19Fluorine magnetic resonance spectroscopy (19FMRS) and 19FMRSI. ALP-mediated hydrolysis of DiFMUP was tested on osteoblastic cells and bone tissue, using serial measurements of fluorescence activity. Extracellular activation of DiFMUP on ALP-positive mouse bone precursor cells was observed. Concurringly, DiFMUP was also activated on bone derived from rat tibia. Marked inhibition of the cell and tissue activation of DiFMUP was detected after the addition of the ALP inhibitor levamisole. 19FMRS and 19FMRSI were applied for the non-invasive measurement of DiFMUP hydrolysis. 19FMRS revealed a two-peak spectrum representing DiFMUP with an associated chemical shift for the hydrolysis product. Activation of DiFMUP by ALP yielded a characteristic pharmacokinetic profile, which was quantifiable using non-localized 19FMRS and enabled the development of a pharmacokinetic model of ALP activity. Application of 19FMRSI facilitated anatomically accurate, non-invasive imaging of ALP concentration and activity in rat bone. Thus, 19FMRSI represents a promising approach for the quantitative imaging of bone cell activity during bone formation with potential for both preclinical and clinical applications. PMID:21799916

Collagen fibril organization within rat vertebral bone modified with metastatic involvement.

PubMed

Burke, Mikhail; Golaraei, Ahmad; Atkins, Ayelet; Akens, Margarete; Barzda, Virginijus; Whyne, Cari

2017-08-01

Metastatic involvement diminishes the mechanical integrity of vertebral bone, however its specific impact on the structural characteristics of a primary constituent of bone tissue, the collagen-I fibril matrix, has not been adequately characterized. Female athymic rats were inoculated with HeLa or Ace-1 cancer cells lines producing osteolytic or mixed (osteolytic & osteoblastic) metastases respectively. A maximum of 21days was allowed between inoculation and rat sacrifice for vertebrae extraction. Linear polarization-in, polarization-out (PIPO) second harmonic generation (SHG) and transmission electron microscopy (TEM) imaging was utilized to assess the impact of metastatic involvement on collagen fibril organization. Increased observations of deviations in the typical plywood motif or a parallel packing structure and an increased average measured susceptibility ratio (related to relative degree of in-plane vs. out-plane fibrils in the analyzed tissue area) in bone adjacent to metastatic involvement was indicative of change in fibrilar organization compared to healthy controls. In particular, collagen-I fibrils in tumour-induced osteoblastic bone growth showed no adherence to the plywood motif or parallel packing structure seen in healthy lamellar bone, exhibiting a much higher susceptibility ratio and degree of fibril disorder. Negative correlations were established between measured susceptibility ratios and the hardness and modulus of metastatic bone tissue assessed in a previous study. Characterizing modifications in tissue level properties is key in defining bone quality in the presence of metastatic disease and their potential impact on material behaviour. Copyright © 2017 Elsevier Inc. All rights reserved.

Piezosurgery in Bone Augmentation Procedures Previous to Dental Implant Surgery: A Review of the Literature

PubMed Central

Magrin, Gabriel Leonardo; Sigua-Rodriguez, Eder Alberto; Goulart, Douglas Rangel; Asprino, Luciana

2015-01-01

The piezosurgery has been used with increasing frequency and applicability by health professionals, especially those who deal with dental implants. The concept of piezoelectricity has emerged in the nineteenth century, but it was applied in oral surgery from 1988 by Tomaso Vercellotti. It consists of an ultrasonic device able to cut mineralized bone tissue, without injuring the adjacent soft tissue. It also has several advantages when compared to conventional techniques with drills and saws, such as the production of a precise, clean and low bleed bone cut that shows positive biological results. In dental implants surgery, it has been used for maxillary sinus lifting, removal of bone blocks, distraction osteogenesis, lateralization of the inferior alveolar nerve, split crest of alveolar ridge and even for dental implants placement. The purpose of this paper is to discuss the use of piezosurgery in bone augmentation procedures used previously to dental implants placement. PMID:26966469

Development of improved connection details for adjacent prestressed member bridges.

DOT National Transportation Integrated Search

2017-06-01

Adjacent prestressed member girder bridges are economical systems for short spans and generally come in two types: adjacent box beam bridges and adjacent voided slab bridges. Each type provides the advantages of having low clearances because of their...

Approximate changes in water levels in wells completed in the Chicot and Evangeline aquifers, 1977-93 and 1992-93, and measured compaction, 1973-92, in the Houston-Galveston region, Texas

USGS Publications Warehouse

Kasmarek, Mark C.; Coplin, L.S.; Campodonico, Al

1993-01-01

This report is one in a series of reports that depict water-level changes since 1977 and compaction of subsurface material since 1973.  The report was prepared in cooperation with the Harris-Galveston Coastal Subsidence District and the City of Houston, and presents maps showing the approximate changes in water levels in wells completed in the Chicot and Evangeline aquifers, 1977-93 and 1992-93 (figs. 1-4), and measured compaction, 1973-92 (figs. 5 and 6), in the Houston-Galveston region.  The Houston-Galveston region includes Harris and Galveston Counties and adjacent parts of Brazoria, Fort Bend, Waller, Montgomery, Liberty, and Chambers Counties.

Three-dimensional finite-element analysis of functional stresses in different bone locations produced by implants placed in the maxillary posterior region of the sinus floor.

PubMed

Koca, Omer Lutfi; Eskitascioglu, Gurcan; Usumez, Aslihan

2005-01-01

Implants placed in the posterior maxilla have lower success rates compared to implants placed in other oral regions. Inadequate bone levels have been suggested as a reason for this differential success rate. The purpose of this study was to determine the amount and localization of functional stresses in implants and adjacent bone locations when the implants were placed in the posterior maxilla in proximity to the sinus using finite element analysis (FEA). A 3-dimensional finite element model of a maxillary posterior section of bone (Type 3) was used in this study. Different bony dimensions were generated to perform nonlinear calculations. A single-piece 4.1x10-mm screw-shaped dental implant system (ITI solid implant) was modeled and inserted into atrophic maxillary models with crestal bone heights of 4, 5, 7, 10, or 13 mm. In some models the implant penetrated the sinus floor. Cobalt-Chromium (Wiron 99) was used as the crown framework material placed onto the implant, and porcelain was used for occlusal surface of the crown. A total average occlusal force (vertical load) of 300 N was applied at the palatal cusp (150 N) and mesial fossa (150 N) of the crown. The implant and superstructure were simulated in finite element software (Pro/Engineer 2000i program). For the porcelain superstructure for bone levels, maximum von Mises stress values were observed on the mesial fossae and palatal cusp. For the bone structure, the maximum von Mises stress values were observed in the palatal cortical bone adjacent to the implant neck. There was no stress within the spongy bone. High stresses occurred within the implants for all bone levels. The maximum von Mises stresses in the implants were localized in the neck of implants for 4- and 5-mm bone levels, but for 7-, 10-, and 13-mm bone levels more even stresses occurred within the implants.

Beads but no collar; the significance of an asymptomatic rib bone healing pattern in infants.

PubMed

Talbert, David

2010-07-01

When a long bone, such as a rib, is broken, the position of the break can be seen in the following weeks by a temporary collar of a collagen based material (callus) which holds the broken ends together during the repair process. However in infants a different pattern is sometimes found at autopsy, in which the repair material occurs as widely spaced "beads" along the shaft of the rib. The consistency of the bead material corresponds to the progress of repair in the normal way, but there is no focal region as would be expected in a clean break or greenstick fracture. It is proposed that this results from micro-fractures in the compact bone forming the outer aspect of the rib when it is bent excessively, during thoracic compression such as required in Cardiopulmonary Resuscitation, (CPR), or when the infant is "grabbed" when about to slip from the hands of a carer. The compact bone surface is covered by a relatively very elastic layer, the periosteum, which carries nerves sensitive to stretch or tearing of this periosteum. It is proposed that the local stretch induced in the periosteum bridging these micro-fractures is insufficient to cause these nerves to signal pain and so the condition is asymptomatic, and may be quite common in infancy. It should not be confused with imposed trauma. Copyright 2010 Elsevier Ltd. All rights reserved.

Methodologies to determine forces on bones and muscles of body segments during exercise, employing compact sensors suitable for use in crowded space vehicles

NASA Technical Reports Server (NTRS)

Figueroa, Fernando

1995-01-01

Work under this grant was carried out by the author and by a graduate research assistant. An instrumented bicycle ergometer was implemented focusing on the stated objective: to estimate the forces exerted by each muscle of the feet, calf, and thigh of an individual while bicycling. The sensors used were light and compact. These were probes to measure muscle EMG activity, miniature accelerometers, miniature load sensors, and small encoders to measure angular positions of the pedal. A methodology was developed and implemented to completely describe the kinematics of the limbs using data from the sensors. This work has been published as a Master's Thesis by the Graduate student supported by the grant. The instrumented ergometer along with the sensors and instrumentation were tested during a KC-135 Zero-Gravity flight in July, 1994. A complete description of the system and the tests performed have been published as a report submitted to NASA Johnson Space Center. The data collected during the KC-135 flight is currently being processed so that a kinematic description of the bicycling experiment will be soon determined. A methodology to estimate the muscle forces has been formulated based on previous work. The methodology involves the use of optimization concepts so that the individual muscle forces that represent variables in dynamic equations of motion may be estimated. Optimization of a criteria (goal) function such as minimization of energy will be used along with constraint equations defined by rigid body equations of motion. Use of optimization principles is necessary, because the equations of motion alone constitute an indeterminate system of equations with respect to the large amount of muscle forces which constitute the variables in these equations. The number of variables is reduced somewhat by using forces measured by the load cells installed on the pedal. These load cells measure pressure and shear forces on the foot. The author and his collaborators at NASA

Improved connection details for adjacent prestressed bridge beams.

DOT National Transportation Integrated Search

2015-03-01

Bridges with adjacent box beams and voided slabs are simply and rapidly constructed, and are well suited to : short to medium spans. The traditional connection between the adjacent members is a shear key lled with a : conventional non-shrink grout...

The Rapid Formation of Localized Compaction Bands Under Hydrostatic Load Leading to Pore-pressure Transients in Compacting Rocks

NASA Astrophysics Data System (ADS)

Faulkner, D.; Leclere, H.; Bedford, J. D.; Behnsen, J.; Wheeler, J.

2017-12-01

Compaction of porous rocks can occur uniformly or within localized deformation bands. The formation of compaction bands and their effects on deformation behaviour are poorly understood. Porosity may be primary and compaction can occur with burial, or it can be produced by metamorphic reactions with a solid volume reduction, that can then undergo collapse. We report results from hydrostatic compaction experiments on porous bassanite (CaSO4.0.5H2O) aggregates. Gypsum (CaSO4.2H2O) is first dehydrated under low effective pressure, 4 MPa, to produce a bassanite aggregate with a porosity of 27%. Compaction is induced by increasing confining pressure at rates from 0.001 MPa/s to 0.02 MPa/s while the sample is maintained at a temperature of 115°C. At slow compaction rates, porosity collapse proceeds smoothly. At higher compaction rates, sudden increases in the pore-fluid pressure occur with a magnitude of 5 MPa. Microstructural investigations using X-ray microtomography and SEM observations show that randomly oriented localized compaction features occur in all samples, where the bulk porosity of 18% outside the band is reduced to 5% inside the band. Previous work on deformation bands has suggested that localized compactive features only form under an elevated differential stress and not under a hydrostatic stress state. The magnitude of the pore-pressure pulses can be explained by the formation of compaction bands. The results indicate that the compaction bands can form by rapid (unstable) propagation across the sample above a critical strain rate, or quasi-statically at low compaction rates without pore-fluid pressure bursts. The absence of pore-fluid pressure bursts at slow compaction rates can be explained by viscous deformation of the bassanite aggregate around the tip of a propagating compaction band, relaxing stress, and promoting stable propagation. Conversely, at higher compaction rates, viscous deformation cannot relax the stress sufficiently and unstable

Diverse Formation Mechanisms for Compact Galaxies

NASA Astrophysics Data System (ADS)

Kim, Jin-Ah; Paudel, Sanjaya; Yoon, Suk-Jin

2018-01-01

Compact, quenched galaxies such as M32 are unusual ones located off the mass - size scaling relation defined by normal galaxies. Still, their formation mechanisms remain unsolved. Here we investigate the evolution of ~100 compact, quenched galaxies at z = 0 identified in the Illustris cosmological simulation. We identify three ways for a galaxy to become a compact one and, often, multiple mechanisms operate in a combined manner. First, stripping is responsible for making about a third of compact galaxies. Stripping removes stars from galaxies, usually while keeping their sizes intact. About one third are galaxies that cease their growth early on after entering into more massive, gigantic halos. Finally, about half of compact galaxies, ~ 35 % of which turn out to undergo stripping, experience the compaction due to the highly centrally concentrated star formation. We discuss the evolutionary path of compact galaxies on the mass – size plane for each mechanism in a broader context of dwarf galaxy formation and evolution.

METHOD OF FORMING ELONGATED COMPACTS

DOEpatents

Larson, H.F.

1959-05-01

A powder compacting procedure and apparatus which produces elongated compacts of Be is described. The powdered metal is placed in a thin metal tube which is chemically compatible to lubricant, powder, atmosphere, and die material and will undergo a high degree of plastic deformation and have intermediate hardness. The tube is capped and placed in the die, and punches are applied to the ends. During the compacting stroke the powder seizes the tube and a thickening and shortening of the tube occurs. The tube is easily removed from the die, split, and peeled from the compact. (T.R.H.)

Compact stars

NASA Astrophysics Data System (ADS)

Estevez-Delgado, Gabino; Estevez-Delgado, Joaquin

2018-05-01

An analysis and construction is presented for a stellar model characterized by two parameters (w, n) associated with the compactness ratio and anisotropy, respectively. The reliability range for the parameter w ≤ 1.97981225149 corresponds with a compactness ratio u ≤ 0.2644959374, the density and pressures are positive, regular and monotonic decrescent functions, the radial and tangential speed of sound are lower than the light speed, moreover, than the plausible stability. The behavior of the speeds of sound are determinate for the anisotropy parameter n, admitting a subinterval where the speeds are monotonic crescent functions and other where we have monotonic decrescent functions for the same speeds, both cases describing a compact object that is also potentially stable. In the bigger value for the observational mass M = 2.05 M⊙ and radii R = 12.957 Km for the star PSR J0348+0432, the model indicates that the maximum central density ρc = 1.283820319 × 1018 Kg/m3 corresponds to the maximum value of the anisotropy parameter and the radial and tangential speed of the sound are monotonic decrescent functions.

Forensic genetic analysis of bone remain samples.

PubMed

Siriboonpiputtana, T; Rinthachai, T; Shotivaranon, J; Peonim, V; Rerkamnuaychoke, B

2018-03-01

DNA typing from degraded human remains is still challenging forensic DNA scientists not only in the prospective of DNA purification but also in the interpretation of established DNA profiles and data manipulation, especially in mass fatalities. In this report, we presented DNA typing protocol to investigate many skeletal remains in different degrees of decomposing. In addition, we established the grading system aiming for prior determination of the association between levels of decomposing and overall STR amplification efficacy. A total of 80 bone samples were subjected to DNA isolation using the modified DNA IQ™ System (Promega, USA) for bone extraction following with STR analysis using the AmpFLSTR Identifiler ® (Thermo Fisher Scientific, USA). In low destruction group, complete STR profiles were observed as 84.4% whereas partial profiles and non-amplified were found as 9.4% and 6.2%, respectively. Moreover, in medium destruction group, both complete and partial STR profiles were observed as 31.2% while 37.5% of this group was unable to amplify. Nevertheless, we could not purify DNA and were unable to generate STR profile in any sample from the high destroyed bone samples. Compact bones such as femur and humerus have high successful amplification rate superior than loose/spongy bones. Furthermore, costal cartilage could be a designate specimen for DNA isolation in a case of the body that was discovered approximately to 3 days after death which enabled to isolate high quality and quantity of DNA, reduce time and cost, and do not require special tools such as freezer mill. Copyright © 2018 Elsevier B.V. All rights reserved.

Accelerated Bone Repair After Plasma Laser Corticotomies

PubMed Central

Leucht, Philipp; Lam, Kentson; Kim, Jae-Beom; Mackanos, Mark A.; Simanovskii, Dmitrii M.; Longaker, Michael T.; Contag, Christopher H.; Schwettman, H Alan; Helms, Jill A.

2007-01-01

Objective: To reveal, on a cellular and molecular level, how skeletal regeneration of a corticotomy is enhanced when using laser-plasma mediated ablation compared with conventional mechanical tissue removal. Summary Background Data: Osteotomies are well-known for their most detrimental side effect: thermal damage. This thermal and mechanical trauma to adjacent bone tissue can result in the untoward consequences of cell death and eventually in a delay in healing. Methods: Murine tibial corticotomies were performed using a conventional saw and a Ti:Sapphire plasma-generated laser that removes tissue with minimal thermal damage. Our analyses began 24 hours after injury and proceeded to postsurgical day 6. We investigated aspects of wound repair ranging from vascularization, inflammation, cell proliferation, differentiation, and bone remodeling. Results: Histology of mouse corticotomy sites uncovered a significant difference in the onset of bone healing; whereas laser corticotomies showed abundant bone matrix deposition at postsurgical day 6, saw corticotomies only exhibited undifferentiated tissue. Our analyses uncovered that cutting bone with a saw caused denaturation of the collagen matrix due to thermal effects. This denatured collagen represented an unfavorable scaffold for subsequent osteoblast attachment, which in turn impeded deposition of a new bony matrix. The matrix degradation induced a prolonged inflammatory reaction at the cut edge to create a surface favorable for osteochondroprogenitor cell attachment. Laser corticotomies were absent of collagen denaturation, therefore osteochondroprogenitor cell attachment was enabled shortly after surgery. Conclusion: In summary, these data demonstrate that corticotomies performed with Ti:Sapphire lasers are associated with a reduced initial inflammatory response at the injury site leading to accelerated osteochondroprogenitor cell migration, attachment, differentiation, and eventually matrix deposition. PMID:17592303

Influence of Chromium-Cobalt-Molybdenum Alloy (ASTM F75) on Bone Ingrowth in an Experimental Animal Model.

PubMed

Zuchuat, Jésica; Berli, Marcelo; Maldonado, Ysaí; Decco, Oscar

2017-12-26

Cr-Co-Mo (ASTM F75) alloy has been used in the medical environment, but its use as a rigid barrier membrane for supporting bone augmentation therapies has not been extensively investigated. In the present study, Cr-Co-Mo membranes of different heights were placed in New Zealand white, male rabbit tibiae to assess the quality and volume of new bone formation, without the use of additional factors. Animals were euthanized at 20, 30, 40, and 60 days. Bone formation was observed in all of the cases, although the tibiae implanted with the standard membranes reached an augmentation of bone volume that agreed with the density values over the timecourse. In all cases, plasmatic exudate was found under the membrane and in contact with the new bone. Histological analysis indicated the presence of a large number of chondroblasts adjacent to the inner membrane surface in the first stages, and osteoblasts and osteocytes were observed under them. The bone formation was appositional. The Cr-Co-Mo alloy provides a scaffold with an adequate microenvironment for vertical bone volume augmentation, and the physical dimensions and disposition of the membrane itself influence the new bone formation.

Influence of Chromium-Cobalt-Molybdenum Alloy (ASTM F75) on Bone Ingrowth in an Experimental Animal Model

PubMed Central

Zuchuat, Jésica; Berli, Marcelo; Maldonado, Ysaí; Decco, Oscar

2017-01-01

Cr-Co-Mo (ASTM F75) alloy has been used in the medical environment, but its use as a rigid barrier membrane for supporting bone augmentation therapies has not been extensively investigated. In the present study, Cr-Co-Mo membranes of different heights were placed in New Zealand white, male rabbit tibiae to assess the quality and volume of new bone formation, without the use of additional factors. Animals were euthanized at 20, 30, 40, and 60 days. Bone formation was observed in all of the cases, although the tibiae implanted with the standard membranes reached an augmentation of bone volume that agreed with the density values over the timecourse. In all cases, plasmatic exudate was found under the membrane and in contact with the new bone. Histological analysis indicated the presence of a large number of chondroblasts adjacent to the inner membrane surface in the first stages, and osteoblasts and osteocytes were observed under them. The bone formation was appositional. The Cr-Co-Mo alloy provides a scaffold with an adequate microenvironment for vertical bone volume augmentation, and the physical dimensions and disposition of the membrane itself influence the new bone formation. PMID:29278372

Roller-compacted concrete pavements.

DOT National Transportation Integrated Search

2010-09-01

Roller-compacted concrete (RCC) gets its name from the heavy vibratory steel drum and rubber-tired rollers used to help compact it into its final form. RCC has similar strength properties and consists of the same basic ingredients as conventional con...

Anatomy and histophysiology of the periosteum: quantification of the periosteal blood supply to the adjacent bone with 85Sr and gamma spectrometry.

PubMed

Chanavaz, M

1995-01-01

The periosteum or periosteal membrane is a continuous composite fibroelastic covering membrane of the bone to which it is intimately linked. Although the bone cortex is the main beneficiary of the principal anatomical and physiological functions of the periosteal membrane, the behavior of the entire bone remains closely influenced by periosteal activity. These principal functions are related to the cortical blood supply, osteogenesis, and muscle and ligament attachments. Through its elastic and contractile nature, it participates in the maintenance of bone shape, and plays an important role in metabolic ionic exchange and physiologic distribution of electro-chemical potential differences across its membranous structure. It has also been suggested that the periosteum may have its own specific proprioceptive property. This paper presents a study of the anatomy and histophysiology of the periosteum, and discusses in detail its main functions of cortical blood supply and osteogenesis. It also presents the third intermediary report on a current study of the quantification of cortical vascularization of femoral bone via the periosteum, using an isotonic salt solution containing 85 Strontium. The afferent-efferent (arterio-venous) flows of this solution in the thigh vascular system of guinea pigs were measured by gamma spectrometry after a series of selective macro- and micro-injections of radioactive salt into the femoral arterial system was carried out. Each vascular territory was meticulously selected and the injections were made according to size, starting with the larger vessels, with or without ligatures of neighboring vessels, going progressively to smaller and smaller vessels with diameters not exceeding 100 microns. The principal technical difficulty at this stage of experimentation was related to the identifying and acquiring of appropriate microcatheters. The study also includes a series of measurements after blockage of the transmuscular blood flow and the

Critical evaluation of root causes of the reduced compactability after roll compaction/dry granulation.

PubMed

Mosig, Johanna; Kleinebudde, Peter

2015-03-01

The influence of lubrication and particle size on the reduced compactability after dry granulation was investigated. Powder cellulose, lactose, magnesium carbonate, and two types of microcrystalline cellulose were roll compacted, granulated, and sieved into particle fractions. Particle fractions were compressed into tablets using internal and external lubrication. Internal lubrication resulted in an overlubrication of the granule material compared with the powder material. This resulted in extraordinary high reduction of compactability after dry granulation for lubricant-sensitive materials. The granule size can cause differences in strength, whereby the degree of this effect was material dependent. The loss in strength with increasing compaction force was comparable for different particles sizes of one material, suggesting a change in material properties independently of the size. Granule hardening could be one reason as for higher compaction forces the integrity of the granule structure survived the compression step. The results demonstrated that granule lubrication mainly influence the degree of the reduced compactability after dry granulation and must be considered for the evaluation of mechanism for this phenomenon. Hardening of the material as well as size enlargement will cause the loss in strength after recompression, but the influence of both depends strongly on the material. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.

Secondary pneumatization of the maxillary sinus in callitrichid primates: insights from immunohistochemistry and bone cell distribution.

PubMed

Smith, Timothy D; Rossie, James B; Cooper, Gregory M; Mooney, Mark P; Siegel, Michael I

2005-08-01

The paranasal sinuses remain elusive both in terms of function and in the proximate mechanism of their development. The present study sought to describe the maxillary sinuses (MSs) in three species of callitrichid primates at birth, a time when secondary pneumatization occurs rapidly in humans. The MSs were examined in serially sectioned and stained slides from the heads of two Callithrix jacchus, one Leontopithecus rosalia, and two Saguinus geoffroyi. Specimens were examined microscopically regarding the distribution of osteoclasts and osteoblasts along the osseous boundaries of the MS and other parts of the maxillary bone. Selected sections were immunohistochemically evaluated for the distribution of osteopontin (OPN), which facilitates osteoclast binding. Taken together, OPN immunoreactivity and bone cell distribution suggested trends of bone resorption/deposition that were consistent among species for the superior (roof) and inferior (floor) boundaries of the MS. Expansion at the roof and floor of the MS appeared to correspond to overall vertical midfacial growth in callitrichids. Much more variability was noted for the lateral (alveolar) and medial (nasal walls) of the MS. Unlike the other species, the nasal wall of Saguinus was static and mostly composed of inferior portions of the nasal capsule that were undergoing endochondral ossification. The variation seen in the alveolar walls may relate to the presence or absence of adjacent structures, although it was noted that adjacency of deciduous molars influenced medial drift of the alveolar wall in Saguinus but not Leontopithecus. The results of this study are largely consistent with the "structural" or "architectural" hypothesis of sinus formation with respect to vertical MS enlargement, and the variable cellular/OPN distribution found along the nasal and alveolar walls was evocative of Witmer's (J Vert Paleontol 1997;17:1-73) epithelial hypothesis in revealing that most expansion occurred in regions unopposed

Comprehensive evaluation of compaction of asphalt pavements and development of compaction monitoring system.

DOT National Transportation Integrated Search

2012-04-01

This study aimed to conduct a comprehensive evaluation of compaction of asphalt pavements and : develop software for monitoring field compaction in real time. In the first phase of this study, the researchers : built several test sections that were c...

Application of continuous-wave terahertz computed tomography for the analysis of chicken bone structure

NASA Astrophysics Data System (ADS)

Li, Bin; Wang, Dayong; Rong, Lu; Zhai, Changchao; Wang, Yunxin; Zhao, Jie

2018-02-01

Terahertz (THz) radiation is able to penetrate many different types of nonpolar and nonmetallic materials without the damaging effects of x-rays. THz technology can be combined with computed tomography (CT) to form THz CT, which is an effective imaging method that is used to visualize the internal structure of a three-dimensional sample as cross-sectional images. Here, we reported an application of THz as the radiation source in CT imaging by replacing the x-rays. In this method, the sample cross section is scanned in all translation and rotation directions. Then, the projection data are reconstructed using a tomographic reconstruction algorithm. Two-dimensional (2-D) cross-sectional images of the chicken ulna were obtained through the continuous-wave (CW) THz CT system. Given by the difference of the THz absorption of different substances, the compact bone and spongy bone inside the chicken ulna are structurally distinguishable in the 2-D cross-sectional images. Using the filtered back projection algorithm, we reconstructed the projection data of the chicken ulna at different projection angle intervals and found that the artifacts and noise in the images are strikingly increased when the projection angle intervals become larger, reflected by the blurred boundary of the compact bone. The quality and fidelity of the 2-D cross-sectional images could be substantially improved by reducing the projection angle intervals. Our experimental data demonstrated a feasible application of the CW THz CT system in biological imaging.

[Experimental-morphologic study of bone tissue reaction to carbon-containing material implantation with initiated X-ray contrast property].

PubMed

Grigorian, A S; Nabiev, F Kh; Golovin, R V

2005-01-01

In experimental study on 15 rabbits (chinchilla) influence of titanium plates implanted lapped on adjacent tissues in the region of the lower jaw body (comparison group) and carbon material with added boron in the concentrations of 8 and 15% (the study group) was studied. Results of the experimental-morphological investigation show that carbon-based materials with boron addition (with its content 8 and 15%) did not impede adaptive rebuilding of bone tissues and in particular bone structure regeneration in the process of reactive rebuilding of the "maternal" bone. Moreover, as the result of reactive processes developing in osseous tissues after implantation of the tested materials their successful integration in surrounding tissue structures was detected.

Epiphyseal abnormalities, trabecular bone loss and articular chondrocyte hypertrophy develop in the long bones of postnatal Ext1-deficient mice.

PubMed

Sgariglia, Federica; Candela, Maria Elena; Huegel, Julianne; Jacenko, Olena; Koyama, Eiki; Yamaguchi, Yu; Pacifici, Maurizio; Enomoto-Iwamoto, Motomi

2013-11-01

Long bones are integral components of the limb skeleton. Recent studies have indicated that embryonic long bone development is altered by mutations in Ext genes and consequent heparan sulfate (HS) deficiency, possibly due to changes in activity and distribution of HS-binding/growth plate-associated signaling proteins. Here we asked whether Ext function is continuously required after birth to sustain growth plate function and long bone growth and organization. Compound transgenic Ext1(f/f);Col2CreERT mice were injected with tamoxifen at postnatal day 5 (P5) to ablate Ext1 in cartilage and monitored over time. The Ext1-deficient mice exhibited growth retardation already by 2weeks post-injection, as did their long bones. Mutant growth plates displayed a severe disorganization of chondrocyte columnar organization, a shortened hypertrophic zone with low expression of collagen X and MMP-13, and reduced primary spongiosa accompanied, however, by increased numbers of TRAP-positive osteoclasts at the chondro-osseous border. The mutant epiphyses were abnormal as well. Formation of a secondary ossification center was significantly delayed but interestingly, hypertrophic-like chondrocytes emerged within articular cartilage, similar to those often seen in osteoarthritic joints. Indeed, the cells displayed a large size and round shape, expressed collagen X and MMP-13 and were surrounded by an abundant Perlecan-rich pericellular matrix not seen in control articular chondrocytes. In addition, ectopic cartilaginous outgrowths developed on the lateral side of mutant growth plates over time that resembled exostotic characteristic of children with Hereditary Multiple Exostoses, a syndrome caused by Ext mutations and HS deficiency. In sum, the data do show that Ext1 is continuously required for postnatal growth and organization of long bones as well as their adjacent joints. Ext1 deficiency elicits defects that can occur in human skeletal conditions including trabecular bone loss

Compact CFB: The next generation CFB boiler

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

Utt, J.

1996-12-31

The next generation of compact circulating fluidized bed (CFB) boilers is described in outline form. The following topics are discussed: compact CFB = pyroflow + compact separator; compact CFB; compact separator is a breakthrough design; advantages of CFB; new design with substantial development history; KUHMO: successful demo unit; KUHMO: good performance over load range with low emissions; KOKKOLA: first commercial unit and emissions; KOKKOLA: first commercial unit and emissions; compact CFB installations; next generation CFB boiler; grid nozzle upgrades; cast segmented vortex finders; vortex finder installation; ceramic anchors; pre-cast vertical bullnose; refractory upgrades; and wet gunning.

Compact Feeding Network for Array Radiations of Spoof Surface Plasmon Polaritons

NASA Astrophysics Data System (ADS)

Xu, Jun Jun; Yin, Jia Yuan; Zhang, Hao Chi; Cui, Tie Jun

2016-03-01

We propose a splitter feeding network for array radiations of spoof surface plasmon polaritons (SPPs), which are guided by ultrathin corrugated metallic strips. Based on the coupled mode theory, SPP fields along a single waveguide in a certain frequency range can be readily coupled into two adjacent branch waveguides with the same propagation constants. We propose to load U-shaped particles anti-symmetrically at the ends of such two branch waveguides, showing a high integration degree of the feeding network. By controlling linear phase modulations produced by the U-shaped particle chain, we demonstrate theoretically and experimentally that the SPP fields based on bound modes can be efficiently radiated to far fields in broadside direction. The proposed method shows that the symmetry of electromagnetic field modes can be exploited to the SPP transmission network, providing potential solutions to compact power dividers and combiners for microwave and optical devices and systems.

Osteopathia striata with cranial sclerosis: clinical, radiological, and bone histological findings in an adolescent girl.

PubMed

Ward, L M; Rauch, F; Travers, R; Roy, M; Montes, J; Chabot, G; Glorieux, F H

2004-08-15

Osteopathia striata with cranial sclerosis (OS-CS) is a rare skeletal dysplasia characterized by linear striations of the long bones, osteosclerosis of the cranium, and extra-skeletal anomalies. We provide a comprehensive description of the skeletal phenotype in a French-Canadian girl with a moderate to severe form of sporadic OS-CS. Multiple medical problems, including anal stenosis and the Pierre-Robin sequence, were evident in the first few years of life. At 14 years, she was fully mobile, with normal intellect and stature. She suffered chronic lower extremity pain in the absence of fractures, as well as severe headaches, unilateral facial paralysis, and bilateral mixed hearing loss. Biochemical indices of bone and mineral metabolism were within normal limits. Bone densitometry showed increased areal bone mineral density in the skull, trunk, and pelvis, but not in the upper and lower extremities. An iliac bone biopsy specimen revealed an increased amount of trabecular bone. Trabeculae were abnormally thick, but there was no evidence of disturbed bone remodeling. In a cranial bone specimen, multiple layers of periosteal bone were found that covered a compact cortical compartment containing tightly packed haversian canals. Bone lamellation was normal in both the iliac and skull samples. Osteoclast differentiation studies showed that peripheral blood osteoclast precursors from this patient formed functional osteoclasts in vitro. Thus, studies of bone metabolism did not explain why bone mass is increased in most skeletal areas of this patient. Cranial histology points to exuberant periosteal bone formation as a potential cause of the cranial sclerosis.

Bone remodeling in onlay beta-tricalcium phosphate and coral grafts to rat calvaria: microcomputerized tomography analysis.

PubMed

Anavi, Yakir; Avishai, Gal; Calderon, Shlomo; Allon, Dror M

2011-08-01

This study was conducted to establish the efficiency of microcomputerized tomography (micro-CT) in detection of trabecular bone remodeling of onlay grafts in a rodent calvaria model, and to compare bone remodeling after onlay grafts with beta-tricalcium phosphate (TCP) or coral calcium carbonate. Ten rats received calvarial onlay blocks-5 with TCP and 5 with coral calcium carbonate. The grafts were fixed with a titanium miniplate screw and were covered with a collagen resorbable membrane. Three months after surgery, the calvaria were segmented, and a serial 3-dimensional micro-CT scan of the calvarium and grafted bone block at 16-micrometer resolution was performed. Image analysis software was used to calculate the percentage of newly formed bone from the total block size. Newly formed bone was present adjacent to the calvarium and screw in all specimens. The mean area of newly formed bone of the total block size ranged from 34.67%-38.34% in the TCP blocks, and from 32.41%-34.72% in the coral blocks. In the TCP blocks, bone remodeling was found to be slightly higher than in the coral blocks. Micro-CT appears to be a precise, reproducible, specimen-nondestructive method of analysis of bone formation in onlay block grafts to rat calvaria.

Learning Non-Adjacent Regularities at Age 0 ; 7

ERIC Educational Resources Information Center

Gervain, Judit; Werker, Janet F.

2013-01-01

One important mechanism suggested to underlie the acquisition of grammar is rule learning. Indeed, infants aged 0 ; 7 are able to learn rules based on simple identity relations (adjacent repetitions, ABB: "wo fe fe" and non-adjacent repetitions, ABA: "wo fe wo", respectively; Marcus et al., 1999). One unexplored issue is…

Relative stability of deep- versus shallow-side bone levels in angular proximal infrabony defects.

PubMed

Heins, P; Hartigan, M; Low, S; Chace, R

1989-01-01

The relative changes with time, in the position of the coronal margin of the mesial and distal bone of proximal, angular infrabony defects, were investigated. Tracings of the radiographs of 51 mandibular posterior sites, treated by flap curettage, with a mean post-surgical duration of 11.8 years, were measured using a digitizer pad. The group consisting of shallow-side sites (N = 51), exhibited no significant change in the bone height with time; however, there was a significant decrease in bone height in the deep-side group (N = 51). The mean area of proximal bone decreased significantly with time. The defects were divided into early (N = 25) and advanced (N = 26) angular groups, and then into deep- and shallow-side subgroups. In the early defect group, there was a significant decrease in the mean bone height of the deep-side subgroup. There were no differences in the changes of mean bone level of the remaining 3 subgroups with time. There was no correlation between changes in bone levels of adjacent mesial and distal sides of angular defects with time (r = 0.27). There was no difference between the deep- and shallow-side groups in the number of sites which gained, lost or evidenced no change in bone height. In the study population, the bone height of 73% of the deep-side, and 84% of the shallow-side sites was either unchanged or in a more coronal position.(ABSTRACT TRUNCATED AT 250 WORDS)

Applications of the direct photon absorption technique for measuring bone mineral content in vivo. Determination of body composition in vivo

NASA Technical Reports Server (NTRS)

Cameron, J. R.

1972-01-01

The bone mineral content, BMC, determined by monoenergetic photon absorption technique, of 29 different locations on the long bones and vertebral columns of 24 skeletons was measured. Compressive tests were made on bone from these locations in which the maximum load and maximum stress were measured. Also the ultimate strain, modulus of elasticity and energy absorbed to failure were determined for compact bone from the femoral diaphysis and cancellous bone from the eighth through eleventh thoracic vertebrae. Correlations and predictive relationships between these parameters were examined to investigate the applicability of using the BMC at sites normally measured in vivo, i.e. radius and ulna in estimating the BMC and/or strength of the spine or femoral neck. It was found that the BMC at sites on the same bone were highly correlated r = 0.95 or better; the BMC at sites on different bones were also highly interrelated, r = 0.85. The BMC at various sites on the long bones could be estimated to between 10 and 15 per cent from the BMC of sites on the radius or ulna.

Alteration of blood clot structures by interleukin-1 beta in association with bone defects healing

PubMed Central

Wang, Xin; Friis, Thor E.; Masci, Paul P.; Crawford, Ross W.; Liao, Wenbo; Xiao, Yin

2016-01-01

The quality of hematomas are crucial for successful early bone defect healing, as the structure of fibrin clots can significantly influence the infiltration of cells, necessary for bone regeneration, from adjacent tissues into the fibrin network. This study investigated if there were structural differences between hematomas from normal and delayed healing bone defects and whether such differences were linked to changes in the expression of IL-1β. Using a bone defect model in rats, we found that the hematomas in the delayed healing model had thinner fibers and denser clot structures. Moreover, IL-1β protein levels were significantly higher in the delayed healing hematomas. The effects of IL-1β on the structural properties of human whole blood clots were evaluated by thrombelastograph (TEG), scanning electronic microscopy (SEM), compressive study, and thrombolytic assays. S-nitrosoglutathione (GSNO) was applied to modulate de novo hematoma structure and the impact on bone healing was evaluated in the delayed healing model. We found that GSNO produced more porous hematomas with thicker fibers and resulted in significantly enhanced bone healing. This study demonstrated that IL-1β and GSNO had opposing effects on clot architecture, the structure of which plays a pivotal role in early bone healing. PMID:27767056

Melorheostosis: a Rare Sclerosing Bone Dysplasia.

PubMed

Kotwal, Anupam; Clarke, Bart L

2017-08-01

Melorheostosis is a rare sclerosing bone dysplasia that affects both cortical bone and adjacent soft tissue structures in a sclerotomal distribution. In this review, we describe the natural history, radiological features, proposed pathogenesis, and management options for this debilitating condition. Since its first description in 1922, about 400 cases of melorheostosis have been reported, either as single reports or in small case series. Melorheostosis affects the appendicular skeleton more commonly than the axial skeleton and usually presents with lower limb deformity. Diagnosis is based on a combination of clinical and radiological features that help differentiate this condition from other sclerosing bone dysplasias. LEM domain-containing protein 3 (LEMD3) gene mutations have been demonstrated in several familial cases, but these have been more strongly correlated with other hereditary dysplasias, such as osteopoikilosis, and are not thought to be the causative gene for melorheostosis. The exact etiology of classic sporadically occurring melorheostosis remains unknown, with possible causes being somatic LEMD3 mutations, somatic mutations in the bone morphogenetic protein/transforming growth factor-beta pathway, mutations in multiple genes, or other non-genetic causes. Management in recent years has involved nitrogen-containing bisphosphonates in addition to traditional orthopedic surgical approaches and physical therapy. Melorheostosis may present as mixed or atypical osseous involvement in addition to the classically described "dripping candle wax" appearance of hyperostosis. Some patients may have overlap with osteopoikilosis or Buschke-Ollendorff syndrome. In the future, better characterization of genetic and developmental factors predisposing to melorheostosis may lead to the development of targeted therapy for this condition, as well as for more commonly encountered skeletal abnormalities.

Epiphyseal abnormalities, trabecular bone loss and articular chondrocyte hypertrophy develop in the long bones of postnatal Ext1-deficient mice1

PubMed Central

Sgariglia, Federica; Candela, Maria Elena; Huegel, Julianne; Jacenko, Olena; Koyama, Eiki; Yamaguchi, Yu; Pacifici, Maurizio; Enomoto-Iwamoto, Motomi

2014-01-01

Long bones are integral components of the limb skeleton. Recent studies have indicated that embryonic long bone development is altered by mutations in Ext genes and consequent heparan sulfate (HS) deficiency, possibly due to changes in activity and distribution of HS-binding/growth plate-associated signaling proteins. Here we asked whether Ext function is continuously required after birth to sustain growth plate function and long bone growth and organization. Compound transgenic Ext1f/f;Col2CreERT mice were injected with tamoxifen at postnatal day 5 (P5) to ablate Ext1 in cartilage and monitored over time. The Ext1-deficient mice exhibited growth retardation already by 2 weeks post-injection, as did their long bones. Mutant growth plates displayed a severe disorganization of chondrocyte columnar organization, a shortened hypertrophic zone with low expression of collagen X and MMP-13, and reduced primary spongiosa accompanied, however, by increased numbers of TRAP-positive osteoclasts at the chondro-osseous border. The mutant epiphyses were abnormal as well. Formation of a secondary ossification center was significantly delayed but interestingly, hypertrophic-like chondrocytes emerged within articular cartilage, similar to those often seen in osteoarthritic joints. Indeed, the cells displayed a large size and round shape, expressed collagen X and MMP-13 and were surrounded by an abundant Perlecan-rich pericellular matrix not seen in control articular chondrocytes. In addition, ectopic cartilaginous by EXT mutations and HS deficiency. In sum, the data do show that Ext1 is continuously required for postnatal growth and organization of long bones as well as their adjacent joints. Ext1 deficiency elicits defects that can occur in human skeletal conditions including trabecular bone loss, osteoarthritis and HME. PMID:23958822

Increased Dickkopf-1 expression accelerates bone cell apoptosis in femoral head osteonecrosis.

PubMed

Ko, Jih-Yang; Wang, Feng-Sheng; Wang, Ching-Jen; Wong, To; Chou, Wen-Yi; Tseng, Shin-Ling

2010-03-01

Intensive bone cell apoptosis contributes to osteonecrosis of femoral head (ONFH). Dickkopf-1 (DKK1) reportedly mediates various types of skeletal disorders. This study investigated whether DKK1 was linked to the occurrence of ONFH. Thirty-nine patients with various stages of ONFH were recruited. Bone specimens were harvested from 34 ONFH patients underwent hip arthroplasty, and from 10 femoral neck fracture patients. Bad, Bcl2 TNFalpha, DKK1, Wnt3a, LRP5, and Axin1 expressions were analyzed by quantitative RT-PCR and ELISA. Apoptotic cells were assayed using terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end-labelling (TUNEL). Primary bone-marrow mesenchymal cells were treated with DKK1 RNA interference and recombinant DKK1 protein. ONFH patients with the histories of being administrated corticosteroids and excessive alcohol consumption had significantly higher Bad and DKK1 mRNA expressions in bone tissue and DKK1 abundances in serum than femoral neck fracture patients. Bone cells adjacent to osteonecrotic bone displayed strong DKK1 immunoreactivity and TUNEL staining. Increased DKK1 expression in bone tissue and serum correlated with Bad expression and TUNEL staining. Serum DKK1 abundance correlated with the severity of ONFH. The DKK1 RNA interference and recombinant DKK1 protein regulated Bad expression and apoptosis of primary bone-marrow mesenchymal cells. Knock down of DKK1 reduced dexamethasone-induced apoptosis of mesenchymal cells. Taken together, promoted DKK1 expression was associated with bone cell apoptosis in the occurrence of ONFH patients with the histories of corticosteroid and alcohol intake and progression of ONFH. DKK1 expression in injured tissue provides new insight into ONFH pathogenesis.

Disruption of collagen/apatite alignment impairs bone mechanical function in osteoblastic metastasis induced by prostate cancer.

PubMed

Sekita, Aiko; Matsugaki, Aira; Nakano, Takayoshi

2017-04-01

Prostate cancer (PCa) frequently metastasizes to the bone, generally inducing osteoblastic alterations that increase bone brittleness. Although there is growing interest in the management of the physical capability of patients with bone metastasis, the mechanism underlying the impairment of bone mechanical function remains unclear. The alignment of both collagen fibrils and biological apatite (BAp) c-axis, together with bone mineral density, is one of the strongest contributors to bone mechanical function. In this study, we analyzed the bone microstructure of the mouse femurs with and without PCa cell inoculation. Histological assessment revealed that the bone-forming pattern in the PCa-bearing bone was non-directional, resulting in a spongious structure, whereas that in the control bone was unidirectional and layer-by-layer, resulting in a compact lamellar structure. The degree of preferential alignment of collagen fibrils and BAp, which was evaluated by quantitative polarized microscopy and microbeam X-ray diffraction, respectively, were significantly lower in the PCa-bearing bone than in the control bone. Material parameters including Young's modulus and toughness, measured by the three-point bending test, were simultaneously decreased in the PCa-bearing bone. Specifically, there was a significant positive correlation between the degree of BAp c-axis orientation and Young's modulus. In conclusion, the impairment of mechanical function in the PCa-bearing bone is attributable to disruption of the anisotropic microstructure of bone in multiple phases. This is the first report demonstrating that cancer bone metastasis induces disruption of the collagen/BAp alignment in long bones, thereby impairing their mechanical function. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

A Method for the Measurement of Acoustic Impedance and Speed of Sound in a Small Region of Bone using a Fused Quartz Rod as a Transmission Line

NASA Astrophysics Data System (ADS)

Hatakeyama, Rokuro; Yoshizawa, Masazumi; Moriya, Tadashi

2000-11-01

Precise correction for γ-ray attenuation in skull bone has been a significant problem in obtaining quantitative single photon emission computed tomography (SPECT) images. The correction for γ-ray attenuation is approximately proportional to the density and thickness of the bone under investigation. If the acoustic impedance and the speed of sound in bone are measurable using ultrasonic techniques, then the density and thickness of the bone sample can be calculated. Whole bone usually consists of three layers, and each layer has a different ultrasonic character. Thus, the speed of sound must be measured in a small section of each layer in order to determine the overall density of whole bone. It is important to measure the attenuation constant in order to determine the appropriate level for the ultrasonic input signal. We have developed a method for measuring the acoustic impedance, speed of sound, and attenuation constant in a small region of a bone sample using a fused quartz rod as a transmission line. In the present study, we obtained the following results: impedance of compact bone; 5.30(±0.40)× 106 kg/(m2s), speed of sound; 3780± 250 m/s, and attenuation constant; 2.70± 0.50 Np/m. These results were used to obtain the densities of compact bone, spongy bone and bone marrow in a bovine bone sample and as well as the density of pig skull bone, which were found to be 1.40± 0.30 g/cm3, 1.19± 0.50 g/cm3, 0.90± 0.30 g/cm3 and 1.26± 0.30 g/cm3, respectively. Using a thin solid transmission line, the proposed method makes it possible to determine the density of a small region of a bone sample. It is expected that the proposed method, which is based on ultrasonic measurement, will be useful for application in brain SPECT.

77 FR 22805 - Meeting of the Compact Council for the National Crime Prevention and Privacy Compact; Correction

Federal Register 2010, 2011, 2012, 2013, 2014

2012-04-17

... Register of April 3, 2012, concerning the date and location of the National Crime Prevention and Privacy Compact Council (Council) created by the National Crime Prevention and Privacy Compact Act of 1998... National Crime Prevention and Privacy Compact; Correction AGENCY: Federal Bureau of Investigation. ACTION...

A systematic review of definitions and classification systems of adjacent segment pathology.

PubMed

Kraemer, Paul; Fehlings, Michael G; Hashimoto, Robin; Lee, Michael J; Anderson, Paul A; Chapman, Jens R; Raich, Annie; Norvell, Daniel C

2012-10-15

Systematic review. To undertake a systematic review to determine how "adjacent segment degeneration," "adjacent segment disease," or clinical pathological processes that serve as surrogates for adjacent segment pathology are classified and defined in the peer-reviewed literature. Adjacent segment degeneration and adjacent segment disease are terms referring to degenerative changes known to occur after reconstructive spine surgery, most commonly at an immediately adjacent functional spinal unit. These can include disc degeneration, instability, spinal stenosis, facet degeneration, and deformity. The true incidence and clinical impact of degenerative changes at the adjacent segment is unclear because there is lack of a universally accepted classification system that rigorously addresses clinical and radiological issues. A systematic review of the English language literature was undertaken and articles were classified using the Grades of Recommendation Assessment, Development, and Evaluation criteria. RESULTS.: Seven classification systems of spinal degeneration, including degeneration at the adjacent segment, were identified. None have been evaluated for reliability or validity specific to patients with degeneration at the adjacent segment. The ways in which terms related to adjacent segment "degeneration" or "disease" are defined in the peer-reviewed literature are highly variable. On the basis of the systematic review presented in this article, no formal classification system for either cervical or thoracolumbar adjacent segment disorders currently exists. No recommendations regarding the use of current classification of degeneration at any segments can be made based on the available literature. A new comprehensive definition for adjacent segment pathology (ASP, the now preferred terminology) has been proposed in this Focus Issue, which reflects the diverse pathology observed at functional spinal units adjacent to previous spinal reconstruction and balances

Effects of calcium phosphate/chitosan composite on bone healing in rats: calcium phosphate induces osteon formation.

PubMed

Fernández, Tulio; Olave, Gilberto; Valencia, Carlos H; Arce, Sandra; Quinn, Julian M W; Thouas, George A; Chen, Qi-Zhi

2014-07-01

Vascularization of an artificial graft represents one of the most significant challenges facing the field of bone tissue engineering. Over the past decade, strategies to vascularize artificial scaffolds have been intensively evaluated using osteoinductive calcium phosphate (CaP) biomaterials in animal models. In this work, we observed that CaP-based biomaterials implanted into rat calvarial defects showed remarkably accelerated formation and mineralization of new woven bone in defects in the initial stages, at a rate of ∼60 μm/day (0.8 mg/day), which was considerably higher than normal bone growth rates (several μm/day, 0.1 mg/day) in implant-free controls of the same age. Surprisingly, we also observed histological evidence of primary osteon formation, indicated by blood vessels in early-region fibrous tissue, which was encapsulated by lamellar osteocyte structures. These were later fully replaced by compact bone, indicating complete regeneration of calvarial bone. Thus, the CaP biomaterial used here is not only osteoinductive, but vasculogenic, and it may have contributed to the bone regeneration, despite an absence of osteons in normal rat calvaria. Further investigation will involve how this strategy can regulate formation of vascularized cortical bone such as by control of degradation rate, and use of models of long, dense bones, to more closely approximate repair of human cortical bone.

Delayed Acquisition of Non-Adjacent Vocalic Distributional Regularities

ERIC Educational Resources Information Center

Gonzalez-Gomez, Nayeli; Nazzi, Thierry

2016-01-01

The ability to compute non-adjacent regularities is key in the acquisition of a new language. In the domain of phonology/phonotactics, sensitivity to non-adjacent regularities between consonants has been found to appear between 7 and 10 months. The present study focuses on the emergence of a posterior-anterior (PA) bias, a regularity involving two…

Application of fracture mechanics to failure in manatee rib bone.

PubMed

Yan, Jiahau; Clifton, Kari B; Reep, Roger L; Mecholsky, John J

2006-06-01

The Florida manatee (Trichechus manatus latirostris) is listed as endangered by the U.S. Department of the Interior. Manatee ribs have different microstructure from the compact bone of other mammals. Biomechanical properties of the manatee ribs need to be better understood. Fracture toughness (K(C)) has been shown to be a good index to assess the mechanical performance of bone. Quantitative fractography can be used in concert with fracture mechanics equations to identify fracture initiating defects/cracks and to calculate the fracture toughness of bone materials. Fractography is a standard technique for analyzing fracture behavior of brittle and quasi-brittle materials. Manatee ribs are highly mineralized and fracture in a manner similar to quasi-brittle materials. Therefore, quantitative fractography was applied to determine the fracture toughness of manatee ribs. Average fracture toughness values of small flexure specimens from six different sizes of manatees ranged from 1.3 to 2.6 MPa(m)(12). Scanning electron microscope (SEM) images show most of the fracture origins were at openings for blood vessels and interlayer spaces. Quantitative fractography and fracture mechanics can be combined to estimate the fracture toughness of the material in manatee rib bone. Fracture toughness of subadult and calf manatees appears to increase as the size of the manatee increases. Average fracture toughness of the manatee rib bone materials is less than the transverse fracture toughness of human and bovine tibia and femur.

Direct current stimulation of bone production in the horse: preliminary study with a "gap healing" model.

PubMed

Collier, M A; Brighton, C T; Norrdin, R; Twardock, A R; Rendano, V T

1985-03-01

The effect of a 20-microA direct-current implantable bone growth stimulator (BGS) on bone production with a "gap healing" model in the horse was evaluated. The right and left 4th metatarsal bones (Mt-4) were used in 7 adult horses to create the "gap healing" model. A 4-mm section of the Mt-4 bone was resected bilaterally in each horse. The BGS was surgically placed into the 7 left Mt-4 defects. The 7 right Mt-4 defects served as controls. Six horses survived the 16-week experimental period. Signs of pain, decreased range of limb motion, or lameness was not observed in any animal during the 16 weeks. None of the animals showed complete healing radiographically. Four stimulated sites showed less periosteal reaction and 2 showed greater reaction than the 6 controls. The greatest amount of periosteal reaction or bone resorption was seen around the screws and plates in both groups. Uptakes of 99mTc-MDP in counts/pixel for control sites and stimulated sites were 7.90 and 8.25 in the "gap defect" and 5.19 and 5.06 in the areas adjacent to the gap defect. The ratio of uptake between the gap defect and adjacent area was 1.5 and 1.58 respectively. Biocompatability of the BGS was excellent; however, 1 horse had a broken cathode wire 5 cm from the generator capsule at 6 weeks. All polyethylene cathode sheaths were fluid filled at 16 weeks. The average mineralization rates were 1.57 +/- 0.34, 1.71 +/- 0.28 mm/day and bone formation activity was 0.0182 +/- 0.171, and 0.0168 +/- 0.0149 mm2/day for control limbs and stimulated limbs, respectively. There was no significant difference between groups in any of the histomorphometric values measured. Direct current (20 microA) did not increase bone production in this experiment. Methods to objectively evaluate electrically induced osteogenesis and a "gap defect" model for BGS research on the horse are discussed. The results provide a basis for additional research on electrical stimulation of fractures in the horse and for dose

Studies of Intercellular Communication and Intracellular Metabolic Responses by Bone Cells to Simulated Weightlessness

NASA Technical Reports Server (NTRS)

Doty, Stephen B.

1997-01-01

Spaceflight affects the weight bearing skeletal tissues by reducing the rate of new bone formation. This effect on the long bones of flown rats has been quantitated but the effect at the cellular level and the mechanism(s) involved are not understood. We are applying electron microscopy, coupled with histochemistry and immunocytochemistry to determine the cellular functions most affected by spaceflight. The emphasis for study of these samples from SLS-1, a 9-day mission, is on the histochemical and structural changes of the endosteal and perivascular osteoblasts found in diaphyseal bone of femur and tibia. Work is still in progress but some findings are described: (1) An expected decrease in alkaline phosphatase activity in osteoblasts from flight animals, but an increase in enzyme activity in the stromal stem cells adjacent to the osteoblast. (2) An increase in osteoclastic TRAP activity in the trabecular bone region in response to spaceflight. (3) A large increase in procollagen containing secretory granules in osteoblasts in the recovery group, and a significant decrease in granule numbers in the flight group.

Mechanics of Ballast Compaction. Volume 1 : Technical Review of Ballast Compaction and Related Topics

DOT National Transportation Integrated Search

1982-03-01

The purpose of the research program on the mechanics of ballast compaction is to determine the influence of mechanical compaction on the ballast physical state and its consequence on the performance of the track structure. This report, which is one o...

Polydopamine mediated assembly of hydroxyapatite nanoparticles and bone morphogenetic protein-2 on magnesium alloys for enhanced corrosion resistance and bone regeneration.

PubMed

Jiang, Yanan; Wang, Bi; Jia, Zhanrong; Lu, Xiong; Fang, Liming; Wang, Kefeng; Ren, Fuzeng

2017-10-01

Magnesium alloys have the great potential to be used as orthopedic implants due to their biodegradability and mechanical resemblance to human cortical bone. However, the rapid degradation in physiological environment with the evolution of hydrogen gas release hinders their clinical applications. In this study, we developed a novel functional and biocompatible coating strategy through polydopamine mediated assembly of hydroxyapatite nanoparticles and growth factor, bone morphogenetic protein-2 (BMP-2), onto the surface of AZ31 Mg alloys. Such functional coating has strong bonding with the substrate and can increase surface hydrophilicity of magnesium alloys. In vitro electrochemical corrosion and hydrogen evolution tests demonstrate that the coating can significantly enhance the corrosion resistance and therefore slow down the degradation of AZ31 Mg alloys. In vitro cell culture reveals that immobilization of HA nanoparticles and BMP-2 can obviously promote cell adhesion and proliferation. Furthermore, in vivo implantation tests indicate that with the synergistic effects of HA nanoparticles and BMP-2, the coating does not cause obvious inflammatory response and can significantly reduce the biodegradation rate of the magnesium alloys and induce the new bone formation adjacent to the implants. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 2750-2761, 2017. © 2017 Wiley Periodicals, Inc.

THE EFFECT OF STRAIN RATE ON FRACTURE TOUGHNESS OF HUMAN CORTICAL BONE: A FINITE ELEMENT STUDY

PubMed Central

Ural, Ani; Zioupos, Peter; Buchanan, Drew; Vashishth, Deepak

2011-01-01

Evaluating the mechanical response of bone under high loading rates is crucial to understanding fractures in traumatic accidents or falls. In the current study, a computational approach based on cohesive finite element modeling was employed to evaluate the effect of strain rate on fracture toughness of human cortical bone. Two-dimensional compact tension specimen models were simulated to evaluate the change in initiation and propagation fracture toughness with increasing strain rate (range: 0.08 to 18 s−1). In addition, the effect of porosity in combination with strain rate was assessed using three-dimensional models of microcomputed tomography-based compact tension specimens. The simulation results showed that bone’s resistance against the propagation of fracture decreased sharply with increase in strain rates up to 1 s−1 and attained an almost constant value for strain rates larger than 1 s−1. On the other hand, initiation fracture toughness exhibited a more gradual decrease throughout the strain rates. There was a significant positive correlation between the experimentally measured number of microcracks and the fracture toughness found in the simulations. Furthermore, the simulation results showed that the amount of porosity did not affect the way initiation fracture toughness decreased with increasing strain rates, whereas it exacerbated the same strain rate effect when propagation fracture toughness was considered. These results suggest that strain rates associated with falls lead to a dramatic reduction in bone’s resistance against crack propagation. The compromised fracture resistance of bone at loads exceeding normal activities indicates a sharp reduction and/or absence of toughening mechanisms in bone during high strain conditions associated with traumatic fracture. PMID:21783112

Immunolocalization of matrix metalloproteinase-13 on bone surface under osteoclasts in rat tibia.

PubMed

Nakamura, Hiroaki; Sato, Ginga; Hirata, Azumi; Yamamoto, Toshio

2004-01-01

Matrix metalloproteinase (MMP)-13 (an interstitial collagenase also called collagenase 3) is involved in degradation of extracellular matrix in various tissues. Using immunohistochemistry and Western blotting, we investigated localization of MMP-13 in rat tibia, to clarify the role of MMP-13 in bone resorption. MMP-13 reactivity was mainly seen on bone surfaces under osteoclasts, and in some osteocytes and their lacunae near osteoclasts. However, immunoreactivity was not seen in chondrocytes or osteoclasts. MMP-13 was also localized on cement lines in the epiphysis. In the growth plate erosion zone, perivascular cells showed MMP-13 reactivity. Immunoelectron microscopy revealed that MMP-13 was localized on the bone surfaces, under the ruffled borders and some clear zones of osteoclasts. Gold-labeled MMP-13 was closely associated with collagen fibrils. Gold labeling was also detected in Golgi apparatus of osteocytes adjacent to osteoclasts and bone lining cells. Western blotting showed that MMP-13 was mainly associated with mineralized bone matrix. These findings suggest that MMP-13 synthesized and secreted by osteoblast-lineage cells is localized under the ruffled borders of osteoclasts. MMP-13 may play an important role in degradation of type I collagen in bone matrix, acting in concert with cathepsin K and MMP-9 produced by osteoclasts. MMP-13 in perivascular cells may be involved in removal of cartilage matrix proteins such as type II collagen and aggrecan.

Cartilage Morphological and Histological Findings After Reconstruction of the Glenoid With an Iliac Crest Bone Graft.

PubMed

Auffarth, Alexander; Resch, Herbert; Matis, Nicholas; Hudelmaier, Martin; Wirth, Wolfgang; Forstner, Rosemarie; Neureiter, Daniel; Traweger, Andreas; Moroder, Philipp

2018-04-01

The J-bone graft is presumably representative of iliac crest bone grafts in general and allows anatomic glenoid reconstruction in cases of bone defects due to recurrent traumatic anterior shoulder dislocations. As a side effect, these grafts have been observed to be covered by some soft, cartilage-like tissue when arthroscopy has been indicated after such procedures. To evaluate the soft tissue covering of J-bone grafts by use of magnetic resonance imaging (MRI) and histological analysis. Case series; Level of evidence, 4. Patients underwent MRI at 1 year after the J-bone graft procedures. Radiological data were digitally processed and evaluated by segmentation of axial images. Independent from the MRI analysis, 2 biopsy specimens of J-bone grafts were harvested for descriptive histological analysis. Segmentation of the images revealed that all grafts were covered by soft tissue. This layer had an average thickness of 0.87 mm compared with 1.96 mm at the adjacent native glenoid. Of the 2 biopsy specimens, one exhibited evident hyaline-like cartilage and the other presented patches of chondrocytes embedded in a glycosaminoglycan-rich extracellular matrix. J-bone grafts are covered by soft tissue that can differentiate into fibrous and potentially hyaline cartilage. This feature may prove beneficial for delaying the onset of dislocation arthropathy of the shoulder.

Effect of crack curvature on stress intensity factors for ASTM standard compact tension specimens

NASA Technical Reports Server (NTRS)

Alam, J.; Mendelson, A.

1983-01-01

The stress intensity factors (SIF) are calculated using the method of lines for the compact tension specimen in tensile and shear loading for curved crack fronts. For the purely elastic case, it was found that as the crack front curvature increases, the SIF value at the center of the specimen decreases while increasing at the surface. For the higher values of crack front curvatures, the maximum value of the SIF occurs at an interior point located adjacent to the surface. A thickness average SIF was computed for parabolically applied shear loading. These results were used to assess the requirements of ASTM standards E399-71 and E399-81 on the shape of crack fronts. The SIF is assumed to reflect the average stress environment near the crack edge.

Practical use of bone scan in patients with an osteoporotic vertebral compression fracture.

PubMed

Jun, Deuk Soo; An, Byoung Keun; Yu, Chang Hun; Hwang, Kyung Hoon; Paik, Je Won

2015-02-01

Rib fractures are one of main causes of chest or flank pain when related to an osteoporotic vertebral compression fracture (OVCF). The authors investigated the incidence and risk factors of rib fracture in 284 patients with OVCF using bone scans and evaluated the feasibility as to whether bone scans could be utilized as a useful screening tool. Hot uptake lesions on ribs were found in 122 cases (43.0%). The factors analyzed were age, sex, number and locations of fractured vertebrae, BMD, and compression rates as determined using initial radiography. However, no statistical significances were found. In 16 cases (5.6%), there were concurrent multiple fractures of both the thoracic and lumbar spines not detected by single site MRI. Sixty cases (21.1%) of OVCF with the a compression rate of less than 15% could not be identified definitely by initial plain radiography, but were confirmed by bone scans. It is concluded that a bone scan has outstanding ability for the screening of rib fractures associated with OVCF. Non-adjacent multiple fractures in both thoracic and lumbar spines and fractures not identified definitely by plain radiography were detected on bone scans, which provided a means for determining management strategies and predicting prognosis.

Degradable poly(anhydride ester) implants: effects of localized salicylic acid release on bone.

PubMed

Erdmann, L; Macedo, B; Uhrich, K E

2000-12-01

Degradable poly(anhydride ester) implants in which the polymer backbone breaks down into salicylic acid (SA) were investigated. In this preliminary work, local release of SA from the poly(anhydride esters), thus classified as 'active polymers', on healthy bone and tissue was evaluated in vivo using a mouse model. Degradable polyanhydrides that break down into inactive by-products were used as control membranes because of their chemical similarity to the active polymers. Small polymer squares were inserted over the exposed palatal bone adjacent to the maxillary first molars. Active polymer membranes were placed on one side of the mouth, control polymers placed on the contra lateral side. Intraoral clinical examination showed that active polymer sites were less swollen and inflamed than control polymer sites. Histopathological examination at day 1 showed essentially no difference between control and active polymers. After 4 days, active polymer sites showed epithelial proliferation to a greater extent than the polyanhydride controls. After 20 days, active polymer sites showed greater thickness of new palatal bone and no resorptive areas, while control polymer sites showed less bone thickness as well as resorption including lacunae involving cementum and dentine. From these preliminary studies, we conclude that active polymers, namely poly(anhydride esters), stimulated new bone formation.

Bloch surface wave structures for high sensitivity detection and compact waveguiding

NASA Astrophysics Data System (ADS)

Khan, Muhammad Umar; Corbett, Brian

2016-01-01

Resonant propagating waves created on the surface of a dielectric multilayer stack, called Bloch surface waves (BSW), can be designed for high sensitivity monitoring of the adjacent refractive index as an alternative platform to the metal-based surface plasmon resonance (SPR) sensing. The resonant wavelength and polarization can be designed by engineering of the dielectric layers unlike the fixed resonance of SPR, while the wide bandwidth low loss of dielectrics permits sharper resonances, longer propagation lengths and thus their use in waveguiding devices. The transparency of the dielectrics allows the excitation and monitoring of surface-bound fluorescent molecules. We review the recent developments in this technology. We show the advantages that can be obtained by using high index contrast layered structures. Operating at 1550 nm wavelengths will allow the BSW sensors to be implemented in the silicon photonics platform where active waveguiding can be used in the realization of compact planar integrated circuits for multi-parameter sensing.

Physically detached 'compact groups'

NASA Technical Reports Server (NTRS)

Hernquist, Lars; Katz, Neal; Weinberg, David H.

1995-01-01

A small fraction of galaxies appear to reside in dense compact groups, whose inferred crossing times are much shorter than a Hubble time. These short crossing times have led to considerable disagreement among researchers attempting to deduce the dynamical state of these systems. In this paper, we suggest that many of the observed groups are not physically bound but are chance projections of galaxies well separated along the line of sight. Unlike earlier similar proposals, ours does not require that the galaxies in the compact group be members of a more diffuse, but physically bound entity. The probability of physically separated galaxies projecting into an apparent compact group is nonnegligible if most galaxies are distributed in thin filaments. We illustrate this general point with a specific example: a simulation of a cold dark matter universe, in which hydrodynamic effects are included to identify galaxies. The simulated galaxy distribution is filamentary and end-on views of these filaments produce apparent galaxy associations that have sizes and velocity dispersions similar to those of observed compact groups. The frequency of such projections is sufficient, in principle, to explain the observed space density of groups in the Hickson catalog. We discuss the implications of our proposal for the formation and evolution of groups and elliptical galaxies. The proposal can be tested by using redshift-independent distance estimators to measure the line-of-sight spatial extent of nearby compact groups.

Compact broadband polarization beam splitter using a symmetric directional coupler with sinusoidal bends.

PubMed

Zhang, Fan; Yun, Han; Wang, Yun; Lu, Zeqin; Chrostowski, Lukas; Jaeger, Nicolas A F

2017-01-15

We design and demonstrate a compact broadband polarization beam splitter (PBS) using a symmetric directional coupler with sinusoidal bends on a silicon-on-insulator platform. The sinusoidal bends in our PBS suppress the power exchange between two parallel symmetric strip waveguides for the transverse-electric (TE) mode, while allowing for the maximum power transfer to the adjacent waveguide for the transverse-magnetic (TM) mode. Our PBS has a nominal coupler length of 8.55 μm, and it has an average extinction ratio (ER) of 12.0 dB for the TE mode, an average ER of 20.1 dB for the TM mode, an average polarization isolation (PI) of 20.6 dB for the through port, and an average PI of 11.5 dB for the cross port, all over a bandwidth of 100 nm.

Compaction managed mirror bend achromat

DOEpatents

Douglas, David [Yorktown, VA

2005-10-18

A method for controlling the momentum compaction in a beam of charged particles. The method includes a compaction-managed mirror bend achromat (CMMBA) that provides a beamline design that retains the large momentum acceptance of a conventional mirror bend achromat. The CMMBA also provides the ability to tailor the system momentum compaction spectrum as desired for specific applications. The CMMBA enables magnetostatic management of the longitudinal phase space in Energy Recovery Linacs (ERLs) thereby alleviating the need for harmonic linearization of the RF waveform.

Bone Densitometry (Bone Density Scan)

MedlinePlus

... News Physician Resources Professions Site Index A-Z Bone Densitometry (DEXA) Bone densitometry, also called dual-energy ... limitations of DEXA Bone Densitometry? What is a Bone Density Scan (DEXA)? Bone density scanning, also called ...

FROM ANEURYSMAL BONE CYST TO TELANGIECTATIC OSTEOSARCOMA WITH METASTASIS IN INGUINAL LYMPH NODES - CASE REPORT.

PubMed

Janevska, Vesna; Spasevska, Liljana; Samardziski, Milan; Nikodinovskai, Violeta; Zhivadinovik, Julija; Trajkovskai, Elizabeta

2015-01-01

Aneurysmal bone cyst is a benign bone lesion composed of blood filled cystic cavities lined by fibrous septa. Its malignant transformation of is a rare event. We report a case of a lesion in the second metatarsal bone in a 29-year-old male, presented as a slight swelling of the right foot. After the curettage had been done, the diagnosis of aneurysmal bone cyst was made but the recurrence occurred 4 years later. The biopsy of the recurrent tumor showed compact neoplastic tissue consistent with diagnosis of giant cell tumor with malignancy. The malignant component was recognized as a high grade sarcoma with osteoid production. A tumor mass with the whole II metatarsal bone was extirpated and a resected part of fibula was transplanted. A year later, another recurrence occurred, an amputation was performed and a teleangiectatic osteosarcoma with ingvinal lymph nodes metastases was diagnosed. No other tumor mass was confirmed, either clinically or by imaging techniques at the time of his third operation. He died 4 months later with multiple pulmonary metastases. We emphasize the importance of team work in order to achieve the accurate diagnosis, highlighting careful radiological examinations, good sampling and awareness of unusual cases in bone tumor pathology.

In vivo assessment of bone healing following Piezotome® ultrasonic instrumentation.

PubMed

Reside, Jonathan; Everett, Eric; Padilla, Ricardo; Arce, Roger; Miguez, Patricia; Brodala, Nadine; De Kok, Ingeborg; Nares, Salvador

2015-04-01

This pilot study evaluated the molecular, histologic, and radiographic healing of bone to instrumentation with piezoelectric or high speed rotary (R) devices over a 3-week healing period. Fourteen Sprague-Dawley rats (Charles River Laboratories International, Inc., Wilmington, MA, USA) underwent bilateral tibial osteotomies prepared in a randomized split-leg design using Piezotome® (P1) (Satelec Acteon, Merignac, France), Piezotome 2® (P2) (Satelec Acteon), High-speed R instrumentation, or sham surgery (S). At 1 week, an osteogenesis array was used to evaluate differences in gene expression while quantitative analysis assessed percentage bone fill (PBF) and bone mineral density (BMD) in the defect, peripheral, and distant regions at 3 weeks. Qualitative histologic evaluation of healing osteotomies was also performed at 3 weeks. At 1 week, expression of 11 and 18 genes involved in bone healing was significantly (p < .05) lower following P1 and P2 instrumentation, respectively, relative to S whereas 16 and 4 genes were lower relative to R. No differences in PBF or BMD were detected between groups within the osteotomy defect. However, significant differences in PBF (p = .020) and BMD (p = .008) were noted along the peripheral region between P2 and R groups, being R the group with the lowest values. Histologically, smooth osteotomy margins were present following instrumentation using P1 or P2 relative to R. Piezoelectric instrumentation favors preservation of bone adjacent to osteotomies while variations in gene expression suggest differences in healing rates due to surgical modality. Bone instrumented by piezoelectric surgery appears less detrimental to bone healing than high-speed R device. © 2013 Wiley Periodicals, Inc.

Spaceflight-Induced Bone Loss Alters Failure Mode and Reduces Bending Strength in Murine Spinal Segments

PubMed Central

Berg-Johansen, Britta; Liebenberg, Ellen C.; Li, Alfred; Macias, Brandon R.; Hargens, Alan R.; Lotz, Jeffrey C.

2017-01-01

Intervertebral disc herniation rates are quadrupled in astronauts following spaceflight. While bending motions are main contributors to herniation, the effects of microgravity on the bending properties of spinal discs are unknown. Consequently, the goal of this study was to quantify the bending properties of tail discs from mice with or without microgravity exposure. Caudal motion segments from six mice returned from a 30-day Bion M1 mission and eight vivarium controls were loaded to failure in four-point bending. After testing, specimens were processed using histology to determine the location of failure, and adjacent motion segments were scanned with micro-computed tomography (μCT) to quantify bone properties. We observed that spaceflight significantly shortened the nonlinear toe region of the force-displacement curve by 32% and reduced the bending strength by 17%. Flight mouse spinal segments tended to fail within the growth plate and epiphyseal bone, while controls tended to fail at the disc-vertebra junction. Spaceflight significantly reduced vertebral bone volume fraction, bone mineral density, and trabecular thickness, which may explain the tendency of flight specimens to fail within the epiphyseal bone. Together, these results indicate that vertebral bone loss during spaceflight may degrade spine bending properties and contribute to increased disc herniation risk in astronauts. PMID:26285046

Comparison of volumetric bone mineral density in the tibial region of interest for ACL reconstruction.

PubMed

Klein, Scott A; Nyland, John; Caborn, David N M; Kocabey, Yavuz; Nawab, Akbar

2005-12-01

Adequate tibial bone mineral density (BMD) is essential to soft tissue graft fixation during anterior cruciate ligament (ACL) reconstruction. The purpose of this study was to compare volumetric bone plug density measurements at the tibial region of interest for ACL reconstruction using a standardized immersion technique and Archimedes' principle. Cancellous bone cores were harvested from the proximal, middle, and distal metaphyseal regions of the lateral tibia and from the standard tibial tunnel location used for ACL reconstruction of 18 cadaveric specimens. Proximal tibial cores displayed 32.6% greater BMD than middle tibial cores and 31.8% greater BMD than distal tibial cores, but did not differ from the BMD of the tibial tunnel cores. Correlational analysis confirmed that the cancellous BMD in the tibial tunnel related to the cancellous BMD of the proximal and distal lateral tibial metaphysis. In conjunction with its adjacent cortical bone, the cancellous BMD of the region used for standard tibial tunnel placement provides an effective foundation for ACL graft fixation. In tibia with poor BMD, bicortical fixation that incorporates cortical bone from the distal tibial tunnel region is recommended.

Objectifying the adjacent and opposite angles: a cultural historical analysis

NASA Astrophysics Data System (ADS)

Daher, Wajeeh; Musallam, Nadera

2018-02-01

The angle topic is central to the development of geometric knowledge. Two of the basic concepts associated with this topic are the adjacent and opposite angles. It is the goal of the present study to analyze, based on the cultural historical semiotics framework, how high-achieving seventh grade students objectify the adjacent and opposite angles' concepts. We videoed the learning of a group of three high-achieving students who used technology, specifically GeoGebra, to explore geometric relations related to the adjacent and opposite angles' concepts. To analyze students' objectification of these concepts, we used the categories of objectification of knowledge (attention and awareness) and the categories of generalization (factual, contextual and symbolic), developed by Radford. The research results indicate that teacher's and students' verbal and visual signs, together with the software dynamic tools, mediated the students' objectification of the adjacent and opposite angles' concepts. Specifically, eye and gestures perceiving were part of the semiosis cycles in which the participating students were engaged and which related to the mathematical signs that signified the adjacent and the opposite angles. Moreover, the teacher's suggestions/requests/questions included/suggested semiotic signs/tools, including verbal signs that helped the students pay attention, be aware of and objectify the adjacent and opposite angles' concepts.

Mammalian bone palaeohistology: a survey and new data with emphasis on island forms

PubMed Central

Scheyer, Torsten M.; Veitschegger, Kristof; Forasiepi, Analia M.; Amson, Eli; Van der Geer, Alexandra A.E.; Van den Hoek Ostende, Lars W.; Hayashi, Shoji; Sánchez-Villagra, Marcelo R.

2015-01-01

The interest in mammalian palaeohistology has increased dramatically in the last two decades. Starting in 1849 via descriptive approaches, it has been demonstrated that bone tissue and vascularisation types correlate with several biological variables such as ontogenetic stage, growth rate, and ecology. Mammalian bone displays a large variety of bone tissues and vascularisation patterns reaching from lamellar or parallel-fibred to fibrolamellar or woven-fibred bone, depending on taxon and individual age. Here we systematically review the knowledge and methods on cynodont and mammalian bone microstructure as well as palaeohistology and discuss potential future research fields and techniques. We present new data on the bone microstructure of two extant marsupial species and of several extinct continental and island placental mammals. Extant marsupials display mainly parallel-fibred primary bone with radial and oblique but mainly longitudinal vascular canals. Three juvenile specimens of the dwarf island hippopotamid Hippopotamus minor from the Late Pleistocene of Cyprus show reticular to plexiform fibrolamellar bone. The island murid Mikrotia magna from the Late Miocene of Gargano, Italy displays parallel-fibred primary bone with reticular vascularisation and strong remodelling in the middle part of the cortex. Leithia sp., the dormouse from the Pleistocene of Sicily, is characterised by a primary bone cortex consisting of lamellar bone and a high amount of compact coarse cancellous bone. The bone cortex of the fossil continental lagomorph Prolagus oeningensis and three fossil species of insular Prolagus displays mainly parallel-fibred primary bone and reticular, radial as well as longitudinal vascularisation. Typical for large mammals, secondary bone in the giant rhinocerotoid Paraceratherium sp. from the Late Oligocene of Turkey is represented by dense Haversian bone. The skeletochronological features of Sinomegaceros yabei, a large-sized deer from the Pleistocene of

Drilling force and temperature of bone under dry and physiological drilling conditions

NASA Astrophysics Data System (ADS)

Xu, Linlin; Wang, Chengyong; Jiang, Min; He, Huiyu; Song, Yuexian; Chen, Hanyuan; Shen, Jingnan; Zhang, Jiayong

2014-11-01

Many researches on drilling force and temperature have been done with the aim to reduce the labour intensiveness of surgery, avoid unnecessary damage and improve drilling quality. However, there has not been a systematic study of mid- and high-speed drilling under dry and physiological conditions(injection of saline). Furthermore, there is no consensus on optimal drilling parameters. To study these parameters under dry and physiological drilling conditions, pig humerus bones are drilled with medical twist drills operated using a wide range of drilling speeds and feed rates. Drilling force and temperature are measured using a YDZ-II01W dynamometer and a NEC TVS-500EX thermal infrared imager, respectively, to evaluate internal bone damage. To evaluate drilling quality, bone debris and hole morphology are observed by SEM(scanning electron microscopy). Changes in drilling force and temperature give similar results during drilling such that the value of each parameter peaks just before the drill penetrates through the osteon of the compact bone into the trabeculae of the spongy bone. Drilling temperatures under physiological conditions are much lower than those observed under dry conditions, while a larger drilling force occurs under physiological conditions than dry conditions. Drilling speed and feed rate have a significant influence on drilling force, temperature, bone debris and hole morphology. The investigation of the effect of drilling force and temperature on internal bone damage reveals that a drilling speed of 4500 r/min and a feed rate of 50 mm/min are recommended for bone drilling under physiological conditions. Drilling quality peaks under these optimal parameter conditions. This paper proposes the optimal drilling parameters under mid- and high-speed surgical drilling, considering internal bone damage and drilling quality, which can be looked as a reference for surgeons performing orthopedic operations.

Powder compaction in systems of bimodal distribution

NASA Technical Reports Server (NTRS)

Chattopadhyay, A. K.; Whittemore, O. J., Jr.

1973-01-01

The compaction of mixtures involving different particle sizes is discussed. The various stages of the compaction process include the rearrangement of particles, the filling of the interstices of the large particles by the smaller ones, and the change in particle size and shape upon further densification through the application of pressure. Experimental approaches and equipment used for compacting material are discussed together with the theoretical relations of the compacting process.

Restoration of a vertical alveolar bone defect by orthodontic relocation of a mesially impacted mandibular first molar.

PubMed

Kim, Sung-Jin; Kim, Jin-Wook; Choi, Tae-Hyun; Lee, Kee-Joon

2015-04-01

An impacted mandibular first molar tends to cause serious bone defects of the adjacent teeth. When choosing between the 2 typical treatment options-extraction or orthodontic relocation of the impacted tooth-the decision should be based on assessment of the prognosis. A 22-year-old man with severe mesioangulation and impaction of the mandibular first molar and a related vertical bone defect on the distal side of the second premolar was treated with extraction of the second molar and orthodontic relocation of the first molar with a retromolar miniscrew. Comprehensive orthodontic treatment involving premolar extraction was conducted. Strategic extraction of the molar and adequate orthodontic movement helped to restore the bone structure on the affected side. This case report suggests the effectiveness of restoration of bone defects by using viable periodontal tissues around the impacted tooth for the longevity of the periodontium. Copyright © 2015 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.

First Reported Cases of Biomechanically Adaptive Bone Modeling in Non-Avian Dinosaurs.

PubMed

Cubo, Jorge; Woodward, Holly; Wolff, Ewan; Horner, John R

2015-01-01

Predator confrontation or predator evasion frequently produces bone fractures in potential prey in the wild. Although there are reports of healed bone injuries and pathologies in non-avian dinosaurs, no previously published instances of biomechanically adaptive bone modeling exist. Two tibiae from an ontogenetic sample of fifty specimens of the herbivorous dinosaur Maiasaura peeblesorum (Ornithopoda: Hadrosaurinae) exhibit exostoses. We show that these outgrowths are cases of biomechanically adaptive periosteal bone modeling resulting from overstrain on the tibia after a fibula fracture. Histological and biomechanical results are congruent with predictions derived from this hypothesis. Histologically, the outgrowths are constituted by radial fibrolamellar periosteal bone tissue formed at very high growth rates, as expected in a process of rapid strain equilibration response. These outgrowths show greater compactness at the periphery, where tensile and compressive biomechanical constraints are higher. Moreover, these outgrowths increase the maximum bending strength in the direction of the stresses derived from locomotion. They are located on the antero-lateral side of the tibia, as expected in a presumably bipedal one year old individual, and in the posterior position of the tibia, as expected in a presumably quadrupedal individual at least four years of age. These results reinforce myological evidence suggesting that Maiasaura underwent an ontogenetic shift from the primitive ornithischian bipedal condition when young to a derived quadrupedal posture when older.

First Reported Cases of Biomechanically Adaptive Bone Modeling in Non-Avian Dinosaurs

PubMed Central

Cubo, Jorge; Woodward, Holly; Wolff, Ewan; Horner, John R.

2015-01-01

Predator confrontation or predator evasion frequently produces bone fractures in potential prey in the wild. Although there are reports of healed bone injuries and pathologies in non-avian dinosaurs, no previously published instances of biomechanically adaptive bone modeling exist. Two tibiae from an ontogenetic sample of fifty specimens of the herbivorous dinosaur Maiasaura peeblesorum (Ornithopoda: Hadrosaurinae) exhibit exostoses. We show that these outgrowths are cases of biomechanically adaptive periosteal bone modeling resulting from overstrain on the tibia after a fibula fracture. Histological and biomechanical results are congruent with predictions derived from this hypothesis. Histologically, the outgrowths are constituted by radial fibrolamellar periosteal bone tissue formed at very high growth rates, as expected in a process of rapid strain equilibration response. These outgrowths show greater compactness at the periphery, where tensile and compressive biomechanical constraints are higher. Moreover, these outgrowths increase the maximum bending strength in the direction of the stresses derived from locomotion. They are located on the antero-lateral side of the tibia, as expected in a presumably bipedal one year old individual, and in the posterior position of the tibia, as expected in a presumably quadrupedal individual at least four years of age. These results reinforce myological evidence suggesting that Maiasaura underwent an ontogenetic shift from the primitive ornithischian bipedal condition when young to a derived quadrupedal posture when older. PMID:26153689

12 years' preservation of maxillary permanent incisors with cervical root fractures adjacent to aggressive periodontitis: Report of a case.

PubMed

Tobiska, Sandra; Krastl, Gabriel

2018-05-17

This case report presents long-term results following horizontal root fracture of both maxillary central incisors in a 19-year-old woman with aggressive periodontitis. Due to extensive marginal bone loss and the close proximity of the fracture lines to the bottoms of the periodontal pockets, the prognosis of both teeth was uncertain at the time of the accident. Nevertheless, a conservative treatment strategy consisting of splinting and nonsurgical periodontal therapy was initiated. Follow-up at 12 years after the start of treatment revealed a stable situation from clinical and radiologic perspectives. Permanent fixation to the adjacent teeth and regular supportive periodontal care were the basis for a favorable long-term prognosis.

Phytoparasitic Nematodes Adjacent to Established Strawberry Plantations

PubMed Central

Crow, R. V.; MacDonald, D. H.

1978-01-01

Plant-nematode populations associated with uncultivated vegetation, adjacent strawberry plants, and alternate crop sites were studied at three locations in Minnesota. At one site (Forest Lake), Paratylenchus projectus, Meloidogyne hapla, and Pratylenchus tenuis were frequently associated with the roots of native vegetation. These nematode species were also present in adjacent strawberry beds. Among alternate crops observed, oats and muskmelon usually supported the fewest nematodes although moderate densities of Xiphinema americanum and P. tenuis were found at one location in plots planted to oats. Pratylenchus tenuis was also found on rye at one location. PMID:19305841

Accuracy of CT-based attenuation correction in PET/CT bone imaging

NASA Astrophysics Data System (ADS)

Abella, Monica; Alessio, Adam M.; Mankoff, David A.; MacDonald, Lawrence R.; Vaquero, Juan Jose; Desco, Manuel; Kinahan, Paul E.

2012-05-01

We evaluate the accuracy of scaling CT images for attenuation correction of PET data measured for bone. While the standard tri-linear approach has been well tested for soft tissues, the impact of CT-based attenuation correction on the accuracy of tracer uptake in bone has not been reported in detail. We measured the accuracy of attenuation coefficients of bovine femur segments and patient data using a tri-linear method applied to CT images obtained at different kVp settings. Attenuation values at 511 keV obtained with a 68Ga/68Ge transmission scan were used as a reference standard. The impact of inaccurate attenuation images on PET standardized uptake values (SUVs) was then evaluated using simulated emission images and emission images from five patients with elevated levels of FDG uptake in bone at disease sites. The CT-based linear attenuation images of the bovine femur segments underestimated the true values by 2.9 ± 0.3% for cancellous bone regardless of kVp. For compact bone the underestimation ranged from 1.3% at 140 kVp to 14.1% at 80 kVp. In the patient scans at 140 kVp the underestimation was approximately 2% averaged over all bony regions. The sensitivity analysis indicated that errors in PET SUVs in bone are approximately proportional to errors in the estimated attenuation coefficients for the same regions. The variability in SUV bias also increased approximately linearly with the error in linear attenuation coefficients. These results suggest that bias in bone uptake SUVs of PET tracers ranges from 2.4% to 5.9% when using CT scans at 140 and 120 kVp for attenuation correction. Lower kVp scans have the potential for considerably more error in dense bone. This bias is present in any PET tracer with bone uptake but may be clinically insignificant for many imaging tasks. However, errors from CT-based attenuation correction methods should be carefully evaluated if quantitation of tracer uptake in bone is important.

Granular compaction by fluidization

NASA Astrophysics Data System (ADS)

Tariot, Alexis; Gauthier, Georges; Gondret, Philippe

2017-06-01

How to arrange a packing of spheres is a scientific question that aroused many fundamental works since a long time from Kepler's conjecture to Edward's theory (S. F. Edwards and R.B.S Oakeshott. Theory of powders. Physica A, 157: 1080-1090, 1989), where the role traditionally played by the energy in statistical problems is replaced by the volume for athermal grains. We present experimental results on the compaction of a granular pile immersed in a viscous fluid when submited to a continuous or bursting upward flow. An initial fluidized bed leads to a well reproduced initial loose packing by the settling of grains when the high enough continuous upward flow is turned off. When the upward flow is then turned on again, we record the dynamical evolution of the bed packing. For a low enough continuous upward flow, below the critical velocity of fluidization, a slow compaction dynamics is observed. Strikingly, a slow compaction can be also observed in the case of "fluidization taps" with bursts of fluid velocity higher than the critical fluidization velocity. The different compaction dynamics is discussed when varying the different control parameters of these "fluidization taps".

Does soil compaction increase floods? A review

NASA Astrophysics Data System (ADS)

Alaoui, Abdallah; Rogger, Magdalena; Peth, Stephan; Blöschl, Günter

2018-02-01

Europe has experienced a series of major floods in the past years which suggests that flood magnitudes may have increased. Land degradation due to soil compaction from crop farming or grazing intensification is one of the potential drivers of this increase. A literature review suggests that most of the experimental evidence was generated at plot and hillslope scales. At larger scales, most studies are based on models. There are three ways in which soil compaction affects floods at the catchment scale: (i) through an increase in the area affected by soil compaction; (ii) by exacerbating the effects of changes in rainfall, especially for highly degraded soils; and (iii) when soil compaction coincides with soils characterized by a fine texture and a low infiltration capacity. We suggest that future research should focus on better synthesising past research on soil compaction and runoff, tailored field experiments to obtain a mechanistic understanding of the coupled mechanical and hydraulic processes, new mapping methods of soil compaction that combine mechanical and remote sensing approaches, and an effort to bridge all disciplines relevant to soil compaction effects on floods.

Blockade of epidermal growth factor receptor signaling in tumor cells and tumor-associated endothelial cells for therapy of androgen-independent human prostate cancer growing in the bone of nude mice.

PubMed

Kim, Sun-Jin; Uehara, Hisanori; Karashima, Takashi; Shepherd, David L; Killion, Jerald J; Fidler, Isaiah J

2003-03-01

We determined whether blockade of the epidermal growth factor receptor (EGF-R) signaling pathway by oral administration of the EGF-R tyrosine kinase inhibitor (PKI 166) alone or in combination with injectable Taxol inhibits the growth of PC-3MM2 human prostate cancer cells in the bone of nude mice. Male nude mice implanted with PC-3MM2 cells in the tibia were treated with oral administrations of PKI 166 or PKI 166 plus injectable Taxol beginning 3 days after implantation. The incidence and size of bone tumors and destruction of bone were determined by digitalized radiography. Expression of epidermal growth factor (EGF), EGF-R, and activated EGF-R in tumor cells and tumor-associated endothelial cells was determined by immunohistochemistry. Oral administration of PKI 166 or PKI 166 plus injectable Taxol reduced the incidence and size of bone tumors and destruction of bone. Immunohistochemical analysis revealed that PC-3MM2 cells growing adjacent to the bone expressed high levels of EGF and activated EGF-R, whereas tumor cells in the adjacent musculature did not. Moreover, endothelial cells within the bone tumor lesions, but not in uninvolved bone or tumors in the muscle, expressed high levels of activated EGF-R. Treatment with PKI 166 and more so with PKI 166 plus Taxol significantly inhibited phosphorylation of EGF-R on tumor and endothelial cells and induced significant apoptosis and endothelial cells within tumor lesions. These data indicate that endothelial cells exposed to EGF produced by tumor cells express activated EGF-R and that targeting EGF-R can produce significant therapeutic effects against prostate cancer bone metastasis.

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.

Shear-enhanced compaction in viscoplastic rocks

NASA Astrophysics Data System (ADS)

Yarushina, V. M.; Podladchikov, Y. Y.

2012-04-01

The phenomenon of mutual influence of compaction and shear deformation was repeatedly reported in the literature over the past years. Dilatancy and shear-enhanced compaction of porous rocks were experimentally observed during both rate-independent and rate-dependent inelastic deformation. Plastic pore collapse was preceding the onset of dilatancy and shear-enhanced compaction. Effective bulk viscosity is commonly used to describe compaction driven fluid flow in porous rocks. Experimental data suggest that bulk viscosity of a fluid saturated rock might be a function of both the effective pressure and the shear stress. Dilatancy and shear-enhanced compaction can alter the transport properties of rocks through their influence on permeability and compaction length scale. Recent investigations show that shear stresses in deep mantle rocks can be responsible for spontaneous development of localized melt-rich bands and segregation of small amounts of melt from the solid rock matrix through shear channeling instability. Usually it is assumed that effective viscosity is a function of porosity only. Thus coupling between compaction and shear deformation is ignored. Spherical model which considers a hollow sphere subjected to homogeneous tractions on the outer boundary as a representative elementary volume succeeded in predicting the volumetric compaction behavior of porous rocks and metals to a hydrostatic pressure in a wide range of porosities. Following the success of this simple model we propose a cylindrical model of void compaction and decompaction due to the non-hydrostatic load. The infinite viscoplastic layer with a cylindrical hole is considered as a representative volume element. The remote boundary of the volume is subjected to a homogeneous non-hydrostatic load such that plane strain conditions are fulfilled through the volume. At some critical values of remote stresses plastic zone develops around the hole. The dependence of the effective bulk viscosity on the

Core decompression of the equine navicular bone: an in vivo study in healthy horses.

PubMed

Jenner, Florien; Kirker-Head, Carl

2011-02-01

To determine the physiologic response of the equine navicular bone to core decompression surgery in healthy horses. Experimental in vivo study. Healthy adult horses (n=6). Core decompression was completed by creating three 2.5-mm-diameter drill channels into the navicular bone under arthroscopic control. The venous (P(V)), arterial (P(A)), articular (P(DIPJ)), and intraosseous pressures (IOP) were recorded before and after decompression drilling. Each IOP measurement consisted of a baseline (IOP(B)) and a stress test (intramedullary injection of saline solution, IOP(S)) recording. Lameness was assessed subjectively and using force plate gait analysis. Fluorochrome bone labeling was performed. Horses were euthanatized at 12 weeks. Navicular bone mineral density (BMD) was measured, and bone histology evaluated. Peak IOP (IOP(max)) after stress testing was significantly (P<.05) reduced immediately after core decompression; however, the magnitude of these effects was decreased at 3 and 6 weeks after decompression. A significant (P<.05) correlation existed between IOP(max) and BMD. No lameness was observed beyond the first week after surgery. Substantial remodeling and neovascularization was evident adjacent the surgery sites. Navicular bone core decompression surgery reduced IOP(max), and, with the exception of a mild short-lived lameness, caused no other adverse effects in healthy horses during the 12-week study period. © Copyright 2011 by The American College of Veterinary Surgeons.

A compact source for bunches of singly charged atomic ions

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

Murböck, T.; Birkl, G.; Schmidt, S.

2016-04-15

We have built, operated, and characterized a compact ion source for low-energy bunches of singly charged atomic ions in a vacuum beam line. It is based on atomic evaporation from an electrically heated oven and ionization by electron impact from a heated filament inside a grid-based ionization volume. An adjacent electrode arrangement is used for ion extraction and focusing by applying positive high-voltage pulses to the grid. The method is particularly suited for experimental environments which require low electromagnetic noise. It has proven simple yet reliable and has been used to produce μs-bunches of up to 10{sup 6} Mg{sup +}more » ions at a repetition rate of 1 Hz. We present the concept, setup and characterizing measurements. The instrument has been operated in the framework of the SpecTrap experiment at the HITRAP facility at GSI/FAIR to provide Mg{sup +} ions for sympathetic cooling of highly charged ions by laser-cooled {sup 24}Mg{sup +}.« less

Variable length adjacent partitioning for PTS based PAPR reduction of OFDM signal

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

Ibraheem, Zeyid T.; Rahman, Md. Mijanur; Yaakob, S. N.

2015-05-15

Peak-to-Average power ratio (PAPR) is a major drawback in OFDM communication. It leads the power amplifier into nonlinear region operation resulting into loss of data integrity. As such, there is a strong motivation to find techniques to reduce PAPR. Partial Transmit Sequence (PTS) is an attractive scheme for this purpose. Judicious partitioning the OFDM data frame into disjoint subsets is a pivotal component of any PTS scheme. Out of the existing partitioning techniques, adjacent partitioning is characterized by an attractive trade-off between cost and performance. With an aim of determining effects of length variability of adjacent partitions, we performed anmore » investigation into the performances of a variable length adjacent partitioning (VL-AP) and fixed length adjacent partitioning in comparison with other partitioning schemes such as pseudorandom partitioning. Simulation results with different modulation and partitioning scenarios showed that fixed length adjacent partition had better performance compared to variable length adjacent partitioning. As expected, simulation results showed a slightly better performance of pseudorandom partitioning technique compared to fixed and variable adjacent partitioning schemes. However, as the pseudorandom technique incurs high computational complexities, adjacent partitioning schemes were still seen as favorable candidates for PAPR reduction.« less

Deep Compaction Control of Sandy Soils

NASA Astrophysics Data System (ADS)

Bałachowski, Lech; Kurek, Norbert

2015-02-01

Vibroflotation, vibratory compaction, micro-blasting or heavy tamping are typical improvement methods for the cohesionless deposits of high thickness. The complex mechanism of deep soil compaction is related to void ratio decrease with grain rearrangements, lateral stress increase, prestressing effect of certain number of load cycles, water pressure dissipation, aging and other effects. Calibration chamber based interpretation of CPTU/DMT can be used to take into account vertical and horizontal stress and void ratio effects. Some examples of interpretation of soundings in pre-treated and compacted sands are given. Some acceptance criteria for compaction control are discussed. The improvement factors are analysed including the normalised approach based on the soil behaviour type index.

Algebraic Bethe ansatz for U(1) invariant integrable models: Compact and non-compact applications

NASA Astrophysics Data System (ADS)

Martins, M. J.; Melo, C. S.

2009-10-01

We apply the algebraic Bethe ansatz developed in our previous paper [C.S. Melo, M.J. Martins, Nucl. Phys. B 806 (2009) 567] to three different families of U(1) integrable vertex models with arbitrary N bond states. These statistical mechanics systems are based on the higher spin representations of the quantum group U[SU(2)] for both generic and non-generic values of q as well as on the non-compact discrete representation of the SL(2,R) algebra. We present for all these models the explicit expressions for both the on-shell and the off-shell properties associated to the respective transfer matrices eigenvalue problems. The amplitudes governing the vectors not parallel to the Bethe states are shown to factorize in terms of elementary building blocks functions. The results for the non-compact SL(2,R) model are argued to be derived from those obtained for the compact systems by taking suitable N→∞ limits. This permits us to study the properties of the non-compact SL(2,R) model starting from systems with finite degrees of freedom.

Bone tumor location in dogs given skeletal irradiation by {sup 239}Pu or {sup 226}Ra

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

Lloyd, R.D.; Taylor, G.N.; Miller, S.C.

1997-10-01

Statistical analyses have indicated that there was a significant difference between dogs injected with bone volume-seeking {sup 226} Ra as compared to those given bone surface-seeking {sup 239}Pu with respect to location within the skeleton of 334 radiation-induced primary bone malignancies. Corresponding differences also were event when dogs given bone volume-seeking {sup 90}Sr or bone surface-seeking {sup 241}Am, {sup 228}Th {sup 248,252}Cf, or {sup 224}Ra (which decays mostly on bone surfaces because of its short, 3.6 d half time) were included along with the {sup 226}Ra or {sup 239}Pu, respectively (562 total tumors). Further analysis suggested that higher values ofmore » percent red marrow (M) and bone turnover rate (R) are correlated with increased probability. of tumor appearance at a particular location within the skeleton for the surface seekers. Proportionately higher values of M and R are associated with skeletal sites containing mostly trabecular bone as compared to those with mostly compact (cortical) bone. Coefficients of determination (r{sup 2}) for the relationship between percent of total tumors vs the combination of percent red marrow and turnover rate (= MR) was about 0.7 for the surface seekers but only about 0.1 for the volume seekers. This indicates that the neoplastic effects of surface seekers, but not volume seekers, are associated with the presence of trabecular bone at the various sites of radio nuclide deposition within the skeleton. 10 refs., 3 tabs.« less

MODFLOW-2000 Ground-Water Model?User Guide to the Subsidence and Aquifer-System Compaction (SUB) Package

USGS Publications Warehouse

Hoffmann, Jörn; Leake, S.A.; Galloway, D.L.; Wilson, Alicia M.

2003-01-01

This report documents a computer program, the Subsidence and Aquifer-System Compaction (SUB) Package, to simulate aquifer-system compaction and land subsidence using the U.S. Geological Survey modular finite-difference ground-water flow model, MODFLOW-2000. The SUB Package simulates elastic (recoverable) compaction and expansion, and inelastic (permanent) compaction of compressible fine-grained beds (interbeds) within the aquifers. The deformation of the interbeds is caused by head or pore-pressure changes, and thus by changes in effective stress, within the interbeds. If the stress is less than the preconsolidation stress of the sediments, the deformation is elastic; if the stress is greater than the preconsolidation stress, the deformation is inelastic. The propagation of head changes within the interbeds is defined by a transient, one-dimensional (vertical) diffusion equation. This equation accounts for delayed release of water from storage or uptake of water into storage in the interbeds. Properties that control the timing of the storage changes are vertical hydraulic diffusivity and interbed thickness. The SUB Package supersedes the Interbed Storage Package (IBS1) for MODFLOW, which assumes that water is released from or taken into storage with changes in head in the aquifer within a single model time step and, therefore, can be reasonably used to simulate only thin interbeds. The SUB Package relaxes this assumption and can be used to simulate time-dependent drainage and compaction of thick interbeds and confining units. The time-dependent drainage can be turned off, in which case the SUB Package gives results identical to those from IBS1. Three sample problems illustrate the usefulness of the SUB Package. One sample problem verifies that the package works correctly. This sample problem simulates the drainage of a thick interbed in response to a step change in head in the adjacent aquifer and closely matches the analytical solution. A second sample problem

Compact dry chemistry instruments.

PubMed

Terashima, K; Tatsumi, N

1999-01-01

Compact dry chemistry instruments are designed for use in point-of-care-testing (POCT). These instruments have a number of advantages, including light weight, compactness, ease of operation, and the ability to provide accurate results in a short time with a very small sample volume. On the other hand, reagent costs are high compared to liquid method. Moreover, differences in accuracy have been found between dry chemistry and the liquid method in external quality assessment scheme. This report examines reagent costs and shows how the total running costs associated with dry chemistry are actually lower than those associated with the liquid method. This report also describes methods for minimizing differences in accuracy between dry chemistry and the liquid method. Use of these measures is expected to increase the effectiveness of compact dry chemistry instruments in POCT applications.

Retrospective study of sonographic findings in bone involvement associated with rotator cuff calcific tendinopathy: preliminary results of a case series.

PubMed

Nogueira-Barbosa, Marcello H; Gregio-Junior, Everaldo; Lorenzato, Mario Muller

2015-01-01

The present study was aimed at investigating bone involvement secondary to rotator cuff calcific tendonitis at ultrasonography. Retrospective study of a case series. The authors reviewed shoulder ultrasonography reports of 141 patients diagnosed with rotator cuff calcific tendonitis, collected from the computer-based data records of their institution over a four-year period. Imaging findings were retrospectively and consensually analyzed by two experienced musculoskeletal radiologists looking for bone involvement associated with calcific tendonitis. Only the cases confirmed by computed tomography were considered for descriptive analysis. Sonographic findings of calcific tendinopathy with bone involvement were observed in 7/141 (~ 5%) patients (mean age, 50.9 years; age range, 42-58 years; 42% female). Cortical bone erosion adjacent to tendon calcification was the most common finding, observed in 7/7 cases. Signs of intraosseous migration were found in 3/7 cases, and subcortical cysts in 2/7 cases. The findings were confirmed by computed tomography. Calcifications associated with bone abnormalities showed no acoustic shadowing at ultrasonography, favoring the hypothesis of resorption phase of the disease. Preliminary results of the present study suggest that ultrasonography can identify bone abnormalities secondary to rotator cuff calcific tendinopathy, particularly the presence of cortical bone erosion.

A new animal model for bone atrophic nonunion: fixation by external fixator.

PubMed

Kaspar, Katharina; Matziolis, Georg; Strube, Patrick; Sentürk, Ufuk; Dormann, Svenja; Bail, Hermann J; Duda, Georg N

2008-12-01

A new small animal model of bone atrophic nonunion was established for investigating the process of bone regeneration by performing cauterization of the periosteum, removal of the local bone marrow, and stabilization with external fixation. The model allows the creation of an atrophic nonunion without the need for a critical size defect. Furthermore, it provides reproducible, well-defined mechanical conditions and minimized physical interference of the implant with the biological processes in the healing zone. Eighty adult Sprague-Dawley rats received an osteotomy of the left femur, stabilized with an external fixator. In half of the animals, the periosteum proximal and distal to the osteotomy was destroyed by cauterization and the adjacent bone marrow was removed (nonunion group). At 2 and 8 weeks after surgery, radiological, biomechanical, histological, and histomorphometrical analyses showed a typical physiological healing in the control group, while the nonunion group was characterized by resorption of the bone ends with some callus formation distant to the osteotomy. At both time points, the callus was composed of significantly less bone and significantly more connective tissue (p < 0.001). In addition, the torsional strength of the osteotomized femur was significantly less in the nonunion group than in the control group, which was comparable to that of the intact femur (p < 0.001). In conclusion, the present model allows the induction of an atrophic nonunion without the need of a critical size defect. It is reproducible, provides standardized biomechanical conditions, and allows minimized interaction of the implant with the healing zone.

Skeletal age assessment in children using an open compact MRI system.

PubMed

Terada, Yasuhiko; Kono, Saki; Tamada, Daiki; Uchiumi, Tomomi; Kose, Katsumi; Miyagi, Ryo; Yamabe, Eiko; Yoshioka, Hiroshi

2013-06-01

MRI may be a noninvasive and alternative tool for skeletal age assessment in children, although few studies have reported on this topic. In this article, skeletal age was assessed over a wide range of ages using an open, compact MRI optimized for the imaging of a child's hand and wrist, and its validity was evaluated. MR images and their three-dimensional segmentation visualized detailed skeletal features of each bone in the hand and wrist. Skeletal age was then independently scored from the MR images by two raters, according to the Tanner-Whitehouse Japan system. The skeletal age assessed by MR rating demonstrated a strong positive correlation with chronological age. The intrarater and inter-rater reproducibilities were significantly high. These results demonstrate the validity and reliability of skeletal age assessment using MRI. Copyright © 2012 Wiley Periodicals, Inc.

Whole bone mechanics and bone quality.

PubMed

Cole, Jacqueline H; van der Meulen, Marjolein C H

2011-08-01

The skeleton plays a critical structural role in bearing functional loads, and failure to do so results in fracture. As we evaluate new therapeutics and consider treatments to prevent skeletal fractures, understanding the basic mechanics underlying whole bone testing and the key principles and characteristics contributing to the structural strength of a bone is critical. We therefore asked: (1) How are whole bone mechanical tests performed and what are the key outcomes measured? (2) How do the intrinsic characteristics of bone tissue contribute to the mechanical properties of a whole bone? (3) What are the effects of extrinsic characteristics on whole bone mechanical behavior? (4) Do environmental factors affect whole bone mechanical properties? We conducted a PubMed search using specific search terms and limiting our included articles to those related to in vitro testing of whole bones. Basic solid mechanics concepts are summarized in the context of whole bone testing and the determinants of whole bone behavior. Whole bone mechanical tests measure structural stiffness and strength from load-deformation data. Whole bone stiffness and strength are a function of total bone mass and the tissue geometric distribution and material properties. Age, sex, genetics, diet, and activity contribute to bone structural performance and affect the incidence of skeletal fractures. Understanding and preventing skeletal fractures is clinically important. Laboratory tests of whole bone strength are currently the only measures for in vivo fracture prediction. In the future, combined imaging and engineering models may be able to predict whole bone strength noninvasively.

Explaining large mortality differences between adjacent counties: a cross-sectional study.

PubMed

Schootman, M; Chien, L; Yun, S; Pruitt, S L

2016-08-02

Extensive geographic variation in adverse health outcomes exists, but global measures ignore differences between adjacent geographic areas, which often have very different mortality rates. We describe a novel application of advanced spatial analysis to 1) examine the extent of differences in mortality rates between adjacent counties, 2) describe differences in risk factors between adjacent counties, and 3) determine if differences in risk factors account for the differences in mortality rates between adjacent counties. We conducted a cross-sectional study in Missouri, USA with 2005-2009 age-adjusted all-cause mortality rate as the outcome and county-level explanatory variables from a 2007 population-based survey. We used a multi-level Gaussian model and a full Bayesian approach to analyze the difference in risk factors relative to the difference in mortality rates between adjacent counties. The average mean difference in the age-adjusted mortality rate between any two adjacent counties was -3.27 (standard deviation = 95.5) per 100,000 population (maximum = 258.80). Six variables were associated with mortality differences: inability to obtain medical care because of cost (β = 2.6), hospital discharge rate (β = 1.03), prevalence of fair/poor health (β = 2.93), and hypertension (β = 4.75) and poverty prevalence (β = 6.08). Examining differences in mortality rates and associated risk factors between adjacent counties provides additional insight for future interventions to reduce geographic disparities.

In vivo microcomputed tomography evaluation of rat alveolar bone and root resorption during orthodontic tooth movement.

PubMed

Ru, Nan; Liu, Sean Shih-Yao; Zhuang, Li; Li, Song; Bai, Yuxing

2013-05-01

To observe the real-time microarchitecture changes of the alveolar bone and root resorption during orthodontic treatment. A 10 g force was delivered to move the maxillary left first molars mesially in twenty 10-week-old rats for 14 days. The first molar and adjacent alveolar bone were scanned using in vivo microcomputed tomography at the following time points: days 0, 3, 7, and 14. Microarchitecture parameters, including bone volume fraction, structure model index, trabecular thickness, trabecular number, and trabecular separation of alveolar bone, were measured on the compression and tension side. The total root volume was measured, and the resorption crater volume at each time point was calculated. Univariate repeated measures analysis of variance with Bonferroni corrections were performed to compare the differences in each parameter between time points with significance level at P < .05. From day 3 to day 7, bone volume fraction, structure model index, trabecular thickness, and trabecular separation decreased significantly on the compression side, but the same parameters increased significantly on the tension side from day 7 to day 14. Root resorption volume of the mesial root increased significantly on day 7 of orthodontic loading. Real-time root and bone resorption during orthodontic movement can be observed in 3 dimensions using in vivo micro-CT. Alveolar bone resorption and root resorption were observed mostly in the apical third on day 7 on the compression side; bone formation was observed on day 14 on the tension side during orthodontic tooth movement.

Blue ellipticals in compact groups

NASA Technical Reports Server (NTRS)

Zepf, Stephen E.; Whitmore, Bradley C.

1990-01-01

By studying galaxies in compact groups, the authors examine the hypothesis that mergers of spiral galaxies make elliptical galaxies. The authors combine dynamical models of the merger-rich compact group environment with stellar evolution models and predict that roughly 15 percent of compact group ellipticals should be 0.15 mag bluer in B - R color than normal ellipticals. The published colors of these galaxies suggest the existence of this predicted blue population, but a normal distribution with large random errors can not be ruled out based on these data alone. However, the authors have new ultraviolet blue visual data which confirm the blue color of the two ellipticals with blue B - R colors for which they have their own colors. This confirmation of a population of blue ellipticals indicates that interactions are occurring in compact groups, but a blue color in one index alone does not require that these ellipticals are recent products of the merger of two spirals. The authors demonstrate how optical spectroscopy in the blue may distinguish between a true spiral + spiral merger and the swallowing of a gas-rich system by an already formed elliptical. The authors also show that the sum of the luminosity of the galaxies in each group is consistent with the hypothesis that the final stage in the evolution of compact group is an elliptical galaxy.

Synthetic Parathyroid Hormone May Augment Bone Volume in Autogenous Grafts: A Study in Rats.

PubMed

dos Santos, Rodrigo A B; Ferreira, Marcelo S; Mafra, Carlos Eduardo S; Holzhausen, Marinella; de Lima, Luiz Antônio Pugliesi Alves; Mendes Pannuti, Cláudio; César Neto, João Batista

2016-01-01

Synthetic parathyroid hormone [PTH(1-34)] has been investigated for its benefits on bone healing and osteoporosis treatment; however, there is little information regarding bone grafts. This study therefore investigates the effect of PTH(1-34) on autogenous bone graft healing. Bone grafts were harvested from the calvarium of rats with a trephine bur (3-mm internal diameter) and placed on the cortex near the mandible angle with a titanium screw. Animals were randomly assigned to group 1 (control): subcutaneous injections of saline solution, three times a week (n = 15); group 2: 2 μg/kg PTH(1-34), three times a week (n = 15); and group 3: 40 μg/kg PTH(1-34), three times a week (n = 15). Thirty days postoperatively, the animals were killed, and specimens (implant + bed + graft) were removed and used for undecalcified sections. The following histometric parameters were evaluated: total bone thickness (TT) (bed + gap + graft), graft thickness (GT) (adjacent to the implant), bone-to-implant contact (BIC), and bone area (BA) (within the limits of the threads). Five additional animals were sacrificed immediately after surgery (zero hour) to register bed and graft sizes before healing. Group 3 showed significantly greater bone gain compared with groups 1 and 2 (TT and GT, P <0.05). In relation to initial thickness (zero hour), groups 1 and 2 showed a total decrease in volume of 15.91% and 20.83%, respectively, whereas group 3 showed a slight bone gain (1.21%). Data analysis revealed a significant difference for group 3 compared with groups 1 and 2 (P <0.01). No differences were observed for BIC and BA (P >0.05). Systemic administration of PTH(1-34) augmented bone volume in autogenous grafts.

A radiograph positioning technique to evaluate prosthetic misfit and bone loss around implants.

PubMed

Lin, Kevin C; Wadhwani, Chandur P K; Sharma, Arun; Finzen, Frederick

2014-02-01

A radiograph positioning device was developed to fit with commercially available film holders and implant systems. The device is indexed to the dental implant body and the adjacent dentition by using an implant placement driver and polyvinyl siloxane occlusal registration material. By fitting the device to a conventional film holder, accurate orthogonal radiographs can monitor changes in bone architecture and prosthetic misfit. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

Specifications for embankment and subgrade compaction.

DOT National Transportation Integrated Search

2005-01-01

Six approaches were developed for specifying embankment and subgrade compaction and/or verifying compaction quality on Virginia Department of Transportation (VDOT) construction projects. These approaches, along with VDOT's current practices, were qua...

Local adjacency metric dimension of sun graph and stacked book graph

NASA Astrophysics Data System (ADS)

Yulisda Badri, Alifiah; Darmaji

2018-03-01

A graph is a mathematical system consisting of a non-empty set of nodes and a set of empty sides. One of the topics to be studied in graph theory is the metric dimension. Application in the metric dimension is the navigation robot system on a path. Robot moves from one vertex to another vertex in the field by minimizing the errors that occur in translating the instructions (code) obtained from the vertices of that location. To move the robot must give different instructions (code). In order for the robot to move efficiently, the robot must be fast to translate the code of the nodes of the location it passes. so that the location vertex has a minimum distance. However, if the robot must move with the vertex location on a very large field, so the robot can not detect because the distance is too far.[6] In this case, the robot can determine its position by utilizing location vertices based on adjacency. The problem is to find the minimum cardinality of the required location vertex, and where to put, so that the robot can determine its location. The solution to this problem is the dimension of adjacency metric and adjacency metric bases. Rodrguez-Velzquez and Fernau combine the adjacency metric dimensions with local metric dimensions, thus becoming the local adjacency metric dimension. In the local adjacency metric dimension each vertex in the graph may have the same adjacency representation as the terms of the vertices. To obtain the local metric dimension of values in the graph of the Sun and the stacked book graph is used the construction method by considering the representation of each adjacent vertex of the graph.

Process for forming coal compacts and product thereof

DOEpatents

Gunnink, Brett; Kanunar, Jayanth; Liang, Zhuoxiong

2002-01-01

A process for forming durable, mechanically strong compacts from coal particulates without use of a binder is disclosed. The process involves applying a compressive stress to a particulate feed comprising substantially water-saturated coal particles while the feed is heated to a final compaction temperature in excess of about 100.degree. C. The water present in the feed remains substantially in the liquid phase throughout the compact forming process. This is achieved by heating and compressing the particulate feed and cooling the formed compact at a pressure sufficient to prevent water present in the feed from boiling. The compacts produced by the process have a moisture content near their water saturation point. As a result, these compacts absorb little water and retain exceptional mechanical strength when immersed in high pressure water. The process can be used to form large, cylindrically-shaped compacts from coal particles (i.e., "coal logs") so that the coal can be transported in a hydraulic coal log pipeline.

Constrained and Unconstrained Partial Adjacent Category Logit Models for Ordinal Response Variables

ERIC Educational Resources Information Center

Fullerton, Andrew S.; Xu, Jun

2018-01-01

Adjacent category logit models are ordered regression models that focus on comparisons of adjacent categories. These models are particularly useful for ordinal response variables with categories that are of substantive interest. In this article, we consider unconstrained and constrained versions of the partial adjacent category logit model, which…

Compaction and Settlement of Existing Embankments

DOT National Transportation Integrated Search

2001-12-01

Unanticipated settlement of compacted earth fill has been a continuing problem for embankments managed by Kansas Department of Transportation (KDOT). This report contains the results of an investigation of current compaction specifications, with part...

The Meaning of a Compact

ERIC Educational Resources Information Center

Wasescha, Anna

2016-01-01

To mark the 30th anniversary of "Campus Compact," leaders from across the network came together in the summer of 2015 to reaffirm a shared commitment to the public purposes of higher education. Campus Compact's 30th Anniversary Action Statement of Presidents and Chancellors is the product of that collective endeavor. In signing the…

Steady state compact toroidal plasma production

DOEpatents

Turner, William C.

1986-01-01

Apparatus and method for maintaining steady state compact toroidal plasmas. A compact toroidal plasma is formed by a magnetized coaxial plasma gun and held in close proximity to the gun electrodes by applied magnetic fields or magnetic fields produced by image currents in conducting walls. Voltage supply means maintains a constant potential across the electrodes producing an increasing magnetic helicity which drives the plasma away from a minimum energy state. The plasma globally relaxes to a new minimum energy state, conserving helicity according to Taylor's relaxation hypothesis, and injecting net helicity into the core of the compact toroidal plasma. Controlling the voltage so as to inject net helicity at a predetermined rate based on dissipative processes maintains or increases the compact toroidal plasma in a time averaged steady state mode.

Enhanced bone screw fixation with biodegradable bone cement in osteoporotic bone model.

PubMed

Juvonen, Tiina; Koistinen, Arto; Kröger, Heikki; Lappalainen, Reijo

2012-09-27

The purpose of this study was to study the potential of novel biodegradable PCL bone cement to improve bone screw fixation strength in osteoporotic bone. The biomechanical properties of bone cement (ε-polycaprolactone, PCL) and fixation strength were studied using biomechanical tests and bone screws fixed in an osteoporotic bone model. Removal torques and pullout strengths were assessed for cortical, self-tapping, and cancellous screws inserted in the osteoporotic bone model (polyurethane foam blocks with polycarbonate plate) with and without PCL bone cement. Open cell and cellular rigid foam blocks with a density of 0.12 g/cm3 were used in this model. Removal torques were significantly (more than six-fold) improved with bone cement for cancellous screws. Furthermore, the bone cement improved pullout strengths three to 12 times over depending on the screw and model material. Biodegradable bone cement turned out to be a very potential material to stabilize screw fixation in osteoporotic bone. The results warrant further research before safe clinical use, especially to clarify clinically relevant factors using real osteoporotic bone under human body conditions and dynamic fatigue testing for long-term performance.

Where are compact groups in the local Universe?

NASA Astrophysics Data System (ADS)

Díaz-Giménez, Eugenia; Zandivarez, Ariel

2015-06-01

Aims: The purpose of this work is to perform a statistical analysis of the location of compact groups in the Universe from observational and semi-analytical points of view. Methods: We used the velocity-filtered compact group sample extracted from the Two Micron All Sky Survey for our analysis. We also used a new sample of galaxy groups identified in the 2M++ galaxy redshift catalogue as tracers of the large-scale structure. We defined a procedure to search in redshift space for compact groups that can be considered embedded in other overdense systems and applied this criterion to several possible combinations of different compact and galaxy group subsamples. We also performed similar analyses for simulated compact and galaxy groups identified in a 2M++ mock galaxy catalogue constructed from the Millennium Run Simulation I plus a semi-analytical model of galaxy formation. Results: We observed that only ~27% of the compact groups can be considered to be embedded in larger overdense systems, that is, most of the compact groups are more likely to be isolated systems. The embedded compact groups show statistically smaller sizes and brighter surface brightnesses than non-embedded systems. No evidence was found that embedded compact groups are more likely to inhabit galaxy groups with a given virial mass or with a particular dynamical state. We found very similar results when the analysis was performed using mock compact and galaxy groups. Based on the semi-analytical studies, we predict that 70% of the embedded compact groups probably are 3D physically dense systems. Finally, real space information allowed us to reveal the bimodal behaviour of the distribution of 3D minimum distances between compact and galaxy groups. Conclusions: The location of compact groups should be carefully taken into account when comparing properties of galaxies in environments that are a priori different. Appendices are available in electronic form at http://www.aanda.orgFull Tables B.1 and B.2

Compaction Behavior of Granular Materials

NASA Astrophysics Data System (ADS)

Endicott, Mark R.; Kenkre, V. M.; Glass, S. Jill; Hurd, Alan J.

1996-03-01

We report the results of our recent study of compaction of granular materials. A theoretical model is developed for the description of the compaction of granular materials exemplified by granulated ceramic powders. Its predictions are compared to observations of uniaxial compaction tests of ceramic granules of PMN-PT, spray dried alumina and rutile. The theoretical model employs a volume-based statistical mechanics treatment and an activation analogy. Results of a computer simulation of random packing of discs in two dimensions are also reported. The effect of type of particle size distribution and other parameters of that distribution on the calculated quantities are discussed. We examine the implications of the results of the simulation for the theoretical model.

Monosodium urate monohydrate crystals inhibit osteoblast viability and function: implications for development of bone erosion in gout.

PubMed

Chhana, Ashika; Callon, Karen E; Pool, Bregina; Naot, Dorit; Watson, Maureen; Gamble, Greg D; McQueen, Fiona M; Cornish, Jillian; Dalbeth, Nicola

2011-09-01

Bone erosion is a common manifestation of chronic tophaceous gout. To investigate the effects of monosodium urate monohydrate (MSU) crystals on osteoblast viability and function. The MTT assay and flow cytometry were used to assess osteoblast cell viability in the MC3T3-E1 and ST2 osteoblast-like cell lines, and primary rat and primary human osteoblasts cultured with MSU crystals. Quantitative real-time PCR and von Kossa stained mineralised bone formation assays were used to assess the effects of MSU crystals on osteoblast differentiation using MC3T3-E1 cells. The numbers of osteoblasts and bone lining cells were quantified in bone samples from patients with gout. MSU crystals rapidly reduced viability in all cell types in a dose-dependent manner. The inhibitory effect on cell viability was independent of crystal phagocytosis and was not influenced by differing crystal length or addition of serum. Long-term culture of MC3T3-E1 cells with MSU crystals showed a reduction in mineralisation and decreased mRNA expression of genes related to osteoblast differentiation such as Runx2, Sp7 (osterix), Ibsp (bone sialoprotein), and Bglap (osteocalcin). Fewer osteoblast and lining cells were present on bone directly adjacent to gouty tophus than bone unaffected by tophus in patients with gout. MSU crystals have profound inhibitory effects on osteoblast viability and differentiation. These data suggest that bone erosion in gout occurs at the tophus-bone interface through alteration of physiological bone turnover, with both excessive osteoclast formation, and reduced osteoblast differentiation from mesenchymal stem cells.

PIXE analysis of elements in gastric cancer and adjacent mucosa

NASA Astrophysics Data System (ADS)

Liu, Qixin; Zhong, Ming; Zhang, Xiaofeng; Yan, Lingnuo; Xu, Yongling; Ye, Simao

1990-04-01

The elemental regional distributions in 20 resected human stomach tissues were obtained using PIXE analysis. The samples were pathologically divided into four types: normal, adjacent mucosa A, adjacent mucosa B and cancer. The targets for PIXE analysis were prepared by wet digestion with a pressure bomb system. P, K, Fe, Cu, Zn and Se were measured and statistically analysed. We found significantly higher concentrations of P, K, Cu, Zn and a higher ratio of Cu compared to Zn in cancer tissue as compared with normal tissue, but statistically no significant difference between adjacent mucosa and cancer tissue was found.

Diffusion-Weighted MRI Assessment of Adjacent Disc Degeneration After Thoracolumbar Vertebral Fractures

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

Noriega, David C., E-mail: dcnoriega1970@gmail.com; Marcia, Stefano, E-mail: stemarcia@gmail.com; Ardura, Francisco, E-mail: fardura@ono.com

ObjectiveThe purpose of this study was to assess, by the mean apparent diffusion coefficient (ADC), if a relationship exists between disc ADC and MR findings of adjacent disc degeneration after thoracolumbar fractures treated by anatomic reduction using vertebral augmentation (VAP).Materials and MethodsTwenty non-consecutive patients (mean age 50.7 years; range 45–56) treated because of vertebral fractures, were included in this study. There were 10 A3.1 and 10 A1.2 fractures (AO classification). Surgical treatment using VAP was applied in 14 cases, and conservative in 6 patients. MRI T2-weighted images and mapping of apparent diffusion coefficient (ADC) of the intervertebral disc adjacent to themore » fractured segment were performed after a mean follow-up of 32 months. A total of 60 discs, 3 per patient, were analysed: infra-adjacent, supra-adjacent and a control disc one level above the supra-adjacent.ResultsNo differences between patients surgically treated and those following a conservative protocol regarding the average ADC values obtained in the 20 control discs analysed were found. Considering all discs, average ADC in the supra-adjacent level was lower than in the infra-adjacent (1.35 ± 0.12 vs. 1.53 ± 0.06; p < 0.001). Average ADC values of the discs used as a control were similar to those of the infra-adjacent level (1.54 ± 0.06). Compared to surgically treated patients, discs at the supra-adjacent fracture level showed statistically significant lower values in cases treated conservatively (p < 0.001). The variation in the delay of surgery had no influence on the average values of ADC at any of the measured levels.ConclusionsADC measurements of the supra-adjacent discs after a mean follow-up of 32 months following thoracolumbar fractures, showed that restoration of the vertebral collapse by minimally invasive VAP prevents posttraumatic disc degeneration.« less

Roller compaction of moist pharmaceutical powders.

PubMed

Wu, C-Y; Hung, W-L; Miguélez-Morán, A M; Gururajan, B; Seville, J P K

2010-05-31

The compression behaviour of powders during roller compaction is dominated by a number of factors, such as process conditions (roll speed, roll gap, feeding mechanisms and feeding speed) and powder properties (particle size, shape, moisture content). The moisture content affects the powder properties, such as the flowability and cohesion, but it is not clear how the moisture content will influence the powder compression behaviour during roller compaction. In this study, the effect of moisture contents on roller compaction behaviour of microcrystalline cellulose (MCC, Avicel PH102) was investigated experimentally. MCC samples of different moisture contents were prepared by mixing as-received MCC powder with different amount of water that was sprayed onto the powder bed being agitated in a rotary mixer. The flowability of these samples were evaluated in terms of the poured angle of repose and flow functions. The moist powders were then compacted using the instrumented roller compactor developed at the University of Birmingham. The flow and compression behaviour during roller compaction and the properties of produced ribbons were examined. It has been found that, as the moisture content increases, the flowability of moist MCC powders decreases and the powder becomes more cohesive. As a consequence of non-uniform flow of powder into the compaction zone induced by the friction between powder and side cheek plates, all produced ribbons have a higher density in the middle and lower densities at the edges. For the ribbons made of powders with high moisture contents, different hydration states across the ribbon width were also identified from SEM images. Moreover, it was interesting to find that these ribbons were split into two halves. This is attributed to the reduction in the mechanical strength of moist powder compacts with high moisture contents produced at high compression pressures. Copyright (c) 2010 Elsevier B.V. All rights reserved.

Compaction of Ductile and Fragile Grains

NASA Astrophysics Data System (ADS)

Creissac, S.; Pouliquen, O.; Dalloz-Dubrujeaud, B.

2009-06-01

The compaction of powders into tablets is widely used in several industries (cosmetics, food, pharmaceutics…). In all these industries, the composition of the initial powder is complex, and the behaviour under compaction is not well known, also the mechanical behaviour of the tablets. The aim of this paper is to understand the behaviour (pressure vs density) of a simplified media made of fragile and ductile powders, varying the relative ratio of each powder. Some compaction experiments were carried out with glass beads (fragile) and Polyethylen Glycol powder (ductile). We observe two typical behaviours, depending on the relative volumic fraction of each component. A transition is pointed out, observing the evolution of the slope of the curve pressure/density. This transition is explained by geometrical considerations during compaction. A model is proposed, based on the assumption that the studied media can be compare to a diphasic material with a continuous phase (the ductile powder) and a discrete phase (the fragile powder). The result of this model is compare to the experimental results of compaction, and give a good prediction of the behaviour of the different mixing, knowing the behaviour of the ductile and the fragile phase separately. These results were also interpreted in terms of Heckel parameter which characterizes the ability of the powder to deform plastically under compaction. Some mechanical tests were also performed to compare the mechanical resitance of the obtained tablets.

Percutaneous Radiofrequency Ablation of Painful Spinal Tumors Adjacent to the Spinal Cord with Real-Time Monitoring of Spinal Canal Temperature: A Prospective Study

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

Nakatsuka, Atsuhiro, E-mail: nakatuka@clin.medic.mie-u.ac.jp; Yamakado, Koichiro; Takaki, Haruyuki

2009-01-15

PurposeTo prospectively evaluate the feasibility, safety, and clinical utility of bone radiofrequency (RF) ablation with real-time monitoring of the spinal canal temperature for the treatment of spinal tumors adjacent to the spinal cord.Materials and MethodsOur Institutional Review Board approved this study. Patients gave informed consent. The inclusion criteria were (a) a painful spinal metastasis and (b) a distance of 1 cm or less between the metastasis and the spinal cord. The thermocouple was placed in the spinal canal under CT fluoroscopic guidance. When the spinal canal temperature reached 45{sup o}C, RF application was immediately stopped. RF ablation was considered technicallymore » successful when the procedure was performed without major complications. Clinical success was defined as a fall in the visual analogue scale score of at least 2 points.ResultsTen patients with spinal tumors measuring 3-8 cm (mean, 4.9 {+-} 1.5 cm) were enrolled. The distance between the tumor and the spinal cord was 1-6 mm (mean, 2.4 {+-} 1.6 mm). All procedures were judged technically successful (100%). The spinal canal temperature did not exceed 45{sup o}C in 9 of the 10 patients (90%). In the remaining patient, the temperature rose to 48{sup o}C, resulting in transient neural damage, although RF application was immediately stopped when the temperature reached 45{sup o}C. Clinical success was achieved within 1 week in all patients (100%).ConclusionBone RF ablation with real-time monitoring of the spinal canal temperature is feasible, safe, and clinically useful for the treatment of painful spinal metastases adjacent to the spinal cord.« less

Repairing Fractured Bones by Use of Bioabsorbable Composites

NASA Technical Reports Server (NTRS)

Farley, Gary L.

2006-01-01

proposed method is further based partly on the conjecture that through-the-thickness reinforcements could be excellent for fixing bone segments for surgical repair. The through-the-thickness reinforcements would superficially resemble nails in both form and function. Denoted small-diameter rods (SDRs) to distinguish them from other narrow rods, these reinforcements would be shot or otherwise inserted through adjacent segments of fractured bone to fix them in their correct relative positions (see figure). Shot insertion would be effected by use an applicator that would amount to a miniaturized and highly refined version of the pneumatic guns often used in carpentry to drive nails and brads. The applicator, envisioned to be about the size of a ball-point-pen, would be driven by pressurized carbon dioxide. To further promote stabilization of the segments, layers of bone glue could be applied to the fracture surfaces prior to insertion of the SDRs. The bone glue could be therapeutically loaded with chemicals to promote growth of bone and fight infection

Correlating particle hardness with powder compaction performance.

PubMed

Cao, Xiaoping; Morganti, Mikayla; Hancock, Bruno C; Masterson, Victoria M

2010-10-01

Assessing particle mechanical properties of pharmaceutical materials quickly and with little material can be very important to early stages of pharmaceutical research. In this study, a wide range of pharmaceutical materials were studied using atomic force microscopy (AFM) nanoindentation. A significant amount of particle hardness and elastic modulus data were provided. Moreover, powder compact mechanical properties of these materials were investigated in order to build correlation between the particle hardness and powder compaction performance. It was found that the materials with very low or high particle hardness most likely exhibit poor compaction performance while the materials with medium particle hardness usually have good compaction behavior. Additionally, the results from this study enriched Hiestand's special case concept on particle hardness and powder compaction performance. This study suggests that the use of AFM nanoindentation can help to screen mechanical properties of pharmaceutical materials at early development stages of pharmaceutical research.

Water-level altitudes 2005 and water-level changes in the Chicot, Evangeline, and Jasper aquifers and compaction 1973-2004 in the Chicot and Evangeline aquifers, Houston-Galveston region, Texas

USGS Publications Warehouse

Kasmarek, Mark C.; Houston, Natalie A.

2005-01-01

This report is one in an annual series of reports that depicts water-level altitudes and water-level changes in the Chicot, Evangeline, and Jasper aquifers, and compaction in the Chicot and Evangeline aquifers in the Houston-Galveston region. The Houston-Galveston region comprises Harris, Galveston, Fort Bend, Waller, and Montgomery Counties and adjacent parts of Brazoria, Grimes, Walker, San Jacinto, Liberty, and Chambers Counties. The report was prepared in cooperation with the Harris-Galveston Coastal Subsidence District, the City of Houston, the Fort Bend Subsidence District, and the Lone Star Groundwater Conservation District. For the Chicot and Evangeline aquifers, maps show approximate water-level altitudes in 2005, water-level changes from 2004 to 2005, and approximate water-level changes from 2000 to 2005, from 1990 to 2005, and from 1977 to 2005 (figs. 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10). For the Jasper aquifer, maps show approximate water-level altitudes in 2005 and water-level changes from 2004 to 2005 and 2000 to 2005 (figs. 11, 12, and 13). The report also contains a map showing borehole extensometer (well equipped with compaction monitor) site locations (fig. 14) and graphs showing measured compaction of subsurface material at these sites from 1973 or later to 2004 (fig. 15).The U.S. Geological Survey (USGS) has published annual reports of water-level altitudes and water-level changes for the Chicot and Evangeline aquifers in the Houston-Galveston region since 1979; and annual reports of same for the Fort Bend subregion (Fort Bend County and adjacent areas) since 1990. The USGS published its first water-level-altitude map for the Jasper aquifer in the greater Houston area (primarily Montgomery County) in 2001. The 2005 water-level-altitude and water-level-change maps for the three aquifers are included in this report.

Water-level altitudes 2006 and water-level changes in the Chicot, Evangeline, and Jasper aquifers and compaction 1973-2005 in the Chicot and Evangeline aquifers, Houston-Galveston region, Texas

USGS Publications Warehouse

Kasmarek, Mark C.; Houston, Natalie A.; Brown, Dexter W.

2006-01-01

This report is one in an annual series of reports that depicts water-level altitudes and water-level changes in the Chicot, Evangeline, and Jasper aquifers, and compaction in the Chicot and Evangeline aquifers in the Houston-Galveston region. The Houston-Galveston region comprises Harris, Galveston, Fort Bend, Waller, and Montgomery Counties and adjacent parts of Brazoria, Grimes, Walker, San Jacinto, Liberty, and Chambers Counties. The report was prepared in cooperation with the Harris-Galveston Coastal Subsidence District, the City of Houston, the Fort Bend Subsidence District, and the Lone Star Groundwater Conservation District. For the Chicot and Evangeline aquifers, maps show approximate water-level altitudes in 2006, water-level changes from 2005 to 2006, and approximate water-level changes from 2001 to 2006, from 1990 to 2006, and from 1977 to 2006 (figs. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10). For the Jasper aquifer, maps show approximate water-level altitudes in 2006 and water-level changes from 2005 to 2006 and 2000 to 2006 (figs. 11, 12, 13). The report also contains a map showing borehole extensometer (well equipped with compaction monitor) site locations (fig. 14) and graphs showing measured compaction of subsurface material at these sites from 1973 or later to 2005 (fig. 15).The U.S. Geological Survey (USGS) has published annual reports of water-level altitudes and water-level changes for the Chicot and Evangeline aquifers in the Houston-Galveston region since 1979; and annual reports of same for the Fort Bend subregion (Fort Bend County and adjacent areas) since 1990. The USGS published its first water-level-altitude map for the Jasper aquifer in the greater Houston area (primarily Montgomery County) in 2001. The 2006 water-level-altitude and water-level-change maps for the three aquifers are included in this report.

Water-level altitudes 2004 and water-level changes in the Chicot, Evangeline, and Jasper aquifers and compaction 1973-2003 in the Chicot and Evangeline aquifers, Houston-Galveston region, Texas

USGS Publications Warehouse

Kasmarek, Mark C.; Lanning-Rush, Jennifer

2004-01-01

This report is one in an annual series of reports that depicts water-level altitudes and water-level changes in the Chicot, Evangeline, and Jasper aquifers, and compaction in the Chicot and Evangeline aquifers in the Houston-Galveston region. The Houston-Galveston region comprises Harris, Galveston, Fort Bend, Waller, and Montgomery Counties and adjacent parts of Brazoria, Grimes, Walker, San Jacinto, Liberty, and Chambers Counties. The report was prepared in cooperation with the Harris-Galveston Coastal Subsidence District, the City of Houston, the Fort Bend Subsidence District, and the Lone Star Groundwater Conservation District. For the Chicot and Evangeline aquifers, maps show approximate water-level altitudes in 2004, water-level changes from 2003 to 2004, approximate water-level changes from 1977 to 2004, and approximate water-level changes from 1990 to 2004 (figs. 1, 2, 3, 4, 5, 6, 7, 8). For the Jasper aquifer, maps show approximate water-level altitudes in 2004 and water-level changes from 2003 to 2004 and 2000 to 2004 (figs. 9, 10, 11). The report also contains a map showing borehole extensometer (well equipped with compaction monitor) site locations (fig. 12) and graphs showing measured compaction of subsurface material at these sites from 1973 or later to 2003 (fig. 13). The U.S. Geological Survey (USGS) has published annual reports of water-level altitudes and water-level changes for the Chicot and Evangeline aquifers in the Houston-Galveston region since 1979; and annual reports of same for the Fort Bend subregion (Fort Bend County and adjacent areas) since 1990. The USGS published its first water-level-altitude map for the Jasper aquifer in the greater Houston area (primarily Montgomery County) in 2001. The 2004 water-level-altitude and water-level-change maps for the three aquifers are included in this report.

Determination of mechanical stiffness of bone by pQCT measurements: correlation with non-destructive mechanical four-point bending test data.

PubMed

Martin, Daniel E; Severns, Anne E; Kabo, J M J Michael

2004-08-01

Mechanical tests of bone provide valuable information about material and structural properties important for understanding bone pathology in both clinical and research settings, but no previous studies have produced applicable non-invasive, quantitative estimates of bending stiffness. The goal of this study was to evaluate the effectiveness of using peripheral quantitative computed tomography (pQCT) data to accurately compute the bending stiffness of bone. Normal rabbit humeri (N=8) were scanned at their mid-diaphyses using pQCT. The average bone mineral densities and the cross-sectional moments of inertia were computed from the pQCT cross-sections. Bending stiffness was determined as a function of the elastic modulus of compact bone (based on the local bone mineral density), cross-sectional moment of inertia, and simulated quasistatic strain rate. The actual bending stiffness of the bones was determined using four-point bending tests. Comparison of the bending stiffness estimated from the pQCT data and the mechanical bending stiffness revealed excellent correlation (R2=0.96). The bending stiffness from the pQCT data was on average 103% of that obtained from the four-point bending tests. The results indicate that pQCT data can be used to accurately determine the bending stiffness of normal bone. Possible applications include temporal quantification of fracture healing and risk management of osteoporosis or other bone pathologies.

Compacting biomass waste materials for use as fuel

NASA Astrophysics Data System (ADS)

Zhang, Ou

Every year, biomass waste materials are produced in large quantity. The combustibles in biomass waste materials make up over 70% of the total waste. How to utilize these waste materials is important to the nation and the world. The purpose of this study is to test optimum processes and conditions of compacting a number of biomass waste materials to form a densified solid fuel for use at coal-fired power plants or ordinary commercial furnaces. Successful use of such fuel as a substitute for or in cofiring with coal not only solves a solid waste disposal problem but also reduces the release of some gases from burning coal which cause health problem, acid rain and global warming. The unique punch-and-die process developed at the Capsule Pipeline Research Center, University of Missouri-Columbia was used for compacting the solid wastes, including waste paper, plastics (both film and hard products), textiles, leaves, and wood. The compaction was performed to produce strong compacts (biomass logs) under room temperature without binder and without preheating. The compaction conditions important to the commercial production of densified biomass fuel logs, including compaction pressure, pressure holding time, back pressure, moisture content, particle size, binder effects, and mold conditions were studied and optimized. The properties of the biomass logs were evaluated in terms of physical, mechanical, and combustion characteristics. It was found that the compaction pressure and the initial moisture content of the biomass material play critical roles in producing high-quality biomass logs. Under optimized compaction conditions, biomass waste materials can be compacted into high-quality logs with a density of 0.8 to 1.2 g/cm3. The logs made from the combustible wastes have a heating value in the range 6,000 to 8,000 Btu/lb which is only slightly (10 to 30%) less than that of subbituminous coal. To evaluate the feasibility of cofiring biomass logs with coal, burn tests were

Compact instrument for fluorescence image-guided surgery

NASA Astrophysics Data System (ADS)

Wang, Xinghua; Bhaumik, Srabani; Li, Qing; Staudinger, V. Paul; Yazdanfar, Siavash

2010-03-01

Fluorescence image-guided surgery (FIGS) is an emerging technique in oncology, neurology, and cardiology. To adapt intraoperative imaging for various surgical applications, increasingly flexible and compact FIGS instruments are necessary. We present a compact, portable FIGS system and demonstrate its use in cardiovascular mapping in a preclinical model of myocardial ischemia. Our system uses fiber optic delivery of laser diode excitation, custom optics with high collection efficiency, and compact consumer-grade cameras as a low-cost and compact alternative to open surgical FIGS systems. Dramatic size and weight reduction increases flexibility and access, and allows for handheld use or unobtrusive positioning over the surgical field.

Adjacent-level arthroplasty following cervical fusion.

PubMed

Rajakumar, Deshpande V; Hari, Akshay; Krishna, Murali; Konar, Subhas; Sharma, Ankit

2017-02-01

OBJECTIVE Adjacent-level disc degeneration following cervical fusion has been well reported. This condition poses a major treatment dilemma when it becomes symptomatic. The potential application of cervical arthroplasty to preserve motion in the affected segment is not well documented, with few studies in the literature. The authors present their initial experience of analyzing clinical and radiological results in such patients who were treated with arthroplasty for new or persistent arm and/or neck symptoms related to neural compression due to adjacent-segment disease after anterior cervical discectomy and fusion (ACDF). METHODS During a 5-year period, 11 patients who had undergone ACDF anterior cervical discectomy and fusion (ACDF) and subsequently developed recurrent neck or arm pain related to adjacent-level cervical disc disease were treated with cervical arthroplasty at the authors' institution. A total of 15 devices were implanted (range of treated levels per patient: 1-3). Clinical evaluation was performed both before and after surgery, using a visual analog scale (VAS) for pain and the Neck Disability Index (NDI). Radiological outcomes were analyzed using pre- and postoperative flexion/extension lateral radiographs measuring Cobb angle (overall C2-7 sagittal alignment), functional spinal unit (FSU) angle, and range of motion (ROM). RESULTS There were no major perioperative complications or device-related failures. Statistically significant results, obtained in all cases, were reflected by an improvement in VAS scores for neck/arm pain and NDI scores for neck pain. Radiologically, statistically significant increases in the overall lordosis (as measured by Cobb angle) and ROM at the treated disc level were observed. Three patients were lost to follow-up within the first year after arthroplasty. In the remaining 8 cases, the duration of follow-up ranged from 1 to 3 years. None of these 8 patients required surgery for the same vertebral level during the follow

Compact orthogonal NMR field sensor

DOEpatents

Gerald, II, Rex E.; Rathke, Jerome W [Homer Glen, IL

2009-02-03

A Compact Orthogonal Field Sensor for emitting two orthogonal electro-magnetic fields in a common space. More particularly, a replacement inductor for existing NMR (Nuclear Magnetic Resonance) sensors to allow for NMR imaging. The Compact Orthogonal Field Sensor has a conductive coil and a central conductor electrically connected in series. The central conductor is at least partially surrounded by the coil. The coil and central conductor are electrically or electro-magnetically connected to a device having a means for producing or inducing a current through the coil and central conductor. The Compact Orthogonal Field Sensor can be used in NMR imaging applications to determine the position and the associated NMR spectrum of a sample within the electro-magnetic field of the central conductor.

Effect of slash on forwarder soil compaction

Treesearch

Timothy P. McDonald; Fernando Seixas

1997-01-01

A study of the effect of slash on forwarder soil compaction was carried out. The level of soil compaction at two soil moisture contents, three slash densities (0, 10, and 20 kg/m2), and two levels of traffic (one and five passes) were measured. Results indicated that, on dry, loamy sand soils, the presence of slash did not decrease soil compaction after one forwarder...

Analysis of imaging characteristics of primary malignant bone tumors in children

PubMed Central

Sun, Yingwei; Liu, Xueyong; Pan, Shinong; Deng, Chunbo; Li, Xiaohan; Guo, Qiyong

2017-01-01

The present study aimed to investigate the imaging characteristics of primary malignant bone tumors in children. The imaging results of 34 children with primary malignant bone tumors confirmed by histopathological diagnosis between March 2008 and January 2014 were retrospectively analyzed. In total, 25 patients had osteosarcoma, with radiography and computed tomography (CT) showing osteolytic bone destruction or/and osteoblastic bone sclerosis, an aggressive periosteal reaction, a soft-tissue mass and cancerous bone. The tumors appeared as mixed magnetic resonance imaging (MRI) signals that were inhomogeneously enhanced. A total of 5 patients presented with Ewing sarcoma, with radiography and CT showing invasive bone destruction and a soft-tissue mass. Of the 5 cases, 2 showed a laminar periosteal reaction. The tumors were shown to have mixed low signal on T1-weighted images (T1WI) and high signal on T2-weighted images (T2WI); 1 case showed marked inhomogeneous enhancement. Another 3 patients exhibited chondrosarcoma. Of these cases, 1 was adjacent to the cortex of the proximal tibia, and presented with local cortical bone destruction and a soft-tissue mass containing scattered punctate and amorphous calcifications. MRI revealed mixed low T1 signal and high T2 signals. Another case was located in the medullary cavity of the distal femur, with radiography revealing a localized periosteal reaction. The tumor appeared with mixed MRI signals, and with involvement of the epiphysis and epiphyseal plates. Radiography and CT of the third case showed bone destruction in the right pubic ramus, with patchy punctate, cambered calcifications in the soft-tissue mass. MRI of the soft-tissue mass revealed isointensity on T1WI and heterogeneous hyperintensity on T2WI. Ossifications and the septum appeared as low T1WI and T2WI. Of the 34 patients, 1 patient presented with lymphoma involving the T12, L1 and L2 vertebrae. CT showed vertebral bone destruction, a soft-tissue mass and a

49 CFR 214.107 - Working over or adjacent to water.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 49 Transportation 4 2014-10-01 2014-10-01 false Working over or adjacent to water. 214.107 Section 214.107 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION RAILROAD WORKPLACE SAFETY Bridge Worker Safety Standards § 214.107 Working over or adjacent to water. (a)...

49 CFR 214.107 - Working over or adjacent to water.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 49 Transportation 4 2012-10-01 2012-10-01 false Working over or adjacent to water. 214.107 Section 214.107 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION RAILROAD WORKPLACE SAFETY Bridge Worker Safety Standards § 214.107 Working over or adjacent to water. (a)...

49 CFR 214.107 - Working over or adjacent to water.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 49 Transportation 4 2011-10-01 2011-10-01 false Working over or adjacent to water. 214.107 Section 214.107 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION RAILROAD WORKPLACE SAFETY Bridge Worker Safety Standards § 214.107 Working over or adjacent to water. (a)...

Bone and fat connection in aging bone.

PubMed

Duque, Gustavo

2008-07-01

The fat and bone connection plays an important role in the pathophysiology of age-related bone loss. This review will focus on the age-induced mechanisms regulating the predominant differentiation of mesenchymal stem cells into adipocytes. Additionally, bone marrow fat will be considered as a diagnostic and therapeutic approach to osteoporosis. There are two types of bone and fat connection. The 'systemic connection', usually seen in obese patients, is hormonally regulated and associated with high bone mass and strength. The 'local connection' happens inside the bone marrow. Increasing amounts of bone marrow fat affect bone turnover through the inhibition of osteoblast function and survival and the promotion of osteoclast differentiation and activation. This interaction is regulated by paracrine secretion of fatty acids and adipokines. Additionally, bone marrow fat could be quantified using noninvasive methods and could be used as a therapeutic approach due to its capacity to transdifferentiate into bone without affecting other types of fat in the body. The bone and fat connection within the bone marrow constitutes a typical example of lipotoxicity. Additionally, bone marrow fat could be used as a new diagnostic and therapeutic approach for osteoporosis in older persons.

Effect of repeated compaction of tablets on tablet properties and work of compaction using an instrumented laboratory tablet press.

PubMed

Gamlen, Michael John Desmond; Martini, Luigi G; Al Obaidy, Kais G

2015-01-01

The repeated compaction of Avicel PH101, dicalcium phosphate dihydrate (DCP) powder, 50:50 DCP/Avicel PH101 and Starch 1500 was studied using an instrumented laboratory tablet press which measures upper punch force, punch displacement and ejection force and operates using a V-shaped compression profile. The measurement of work compaction was demonstrated, and the test materials were ranked in order of compaction behaviour Avicel PH101 > DCP/Avicel PH101 > Starch > DCP. The behaviour of the DCP/Avicel PH101 mixture was distinctly non-linear compared with the pure components. Repeated compaction and precompression had no effect on the tensile fracture strength of Avicel PH101 tablets, although small effects on friability and disintegration time were seen. Repeated compaction and precompression reduced the tensile strength and the increased disintegration time of the DCP tablets, but improved the strength and friability of Starch 1500 tablets. Based on the data reported, routine laboratory measurement of tablet work of compaction may have potential as a critical quality attribute of a powder blend for compression. The instrumented press was suitable for student use with minimal supervisor input.

Dose equivalent near the bone-soft tissue interface from nuclear fragments produced by high-energy protons

NASA Technical Reports Server (NTRS)

Shavers, M. R.; Poston, J. W.; Cucinotta, F. A.; Wilson, J. W.

1996-01-01

During manned space missions, high-energy nucleons of cosmic and solar origin collide with atomic nuclei of the human body and produce a broad linear energy transfer spectrum of secondary particles, called target fragments. These nuclear fragments are often more biologically harmful than the direct ionization of the incident nucleon. That these secondary particles increase tissue absorbed dose in regions adjacent to the bone-soft tissue interface was demonstrated in a previous publication. To assess radiological risks to tissue near the bone-soft tissue interface, a computer transport model for nuclear fragments produced by high energy nucleons was used in this study to calculate integral linear energy transfer spectra and dose equivalents resulting from nuclear collisions of 1-GeV protons transversing bone and red bone marrow. In terms of dose equivalent averaged over trabecular bone marrow, target fragments emitted from interactions in both tissues are predicted to be at least as important as the direct ionization of the primary protons-twice as important, if recently recommended radiation weighting factors and "worst-case" geometry are used. The use of conventional dosimetry (absorbed dose weighted by aa linear energy transfer-dependent quality factor) as an appropriate framework for predicting risk from low fluences of high-linear energy transfer target fragments is discussed.

PMMA-hydroxyapatite composite material retards fatigue failure of augmented bone compared to augmentation with plain PMMA: in vivo study using a sheep model.

PubMed

Arabmotlagh, Mohammad; Bachmaier, Samuel; Geiger, Florian; Rauschmann, Michael

2014-11-01

Polymethylmethacrylate (PMMA) is the most commonly used void filler for augmentation of osteoporotic vertebral fracture, but the differing mechanical features of PMMA and osteoporotic bone result in overload and failure of adjacent bone. The aim of this study was to compare fatigue failure of bone after augmentation with PMMA-nanocrystalline hydroxyapatite (HA) composite material or with plain PMMA in a sheep model. After characterization of the mechanical properties of a composite material consisting of PMMA and defined amounts (10, 20, and 30% volume fraction) of HA, the composite material with 30% volume fraction HA was implanted in one distal femur of sheep; plain PMMA was implanted in the other femur. Native non-augmented bone served as control. Three and 6 months after implantation, the augmented bone samples were exposed to cyclic loading and the evolution of damage was investigated. The fatigue life was highest for the ovine native bone and lowest for bone-PMMA specimens. Bone-composite specimens showed significantly higher fatigue life than the respective bone-PMMA specimens in both 3- and 6-month follow-up groups. These results suggest that modification of mechanical properties of PMMA by addition of HA to approximate those of cancellous bone retards fatigue failure of the surrounding bone compared to augmented bone with plain PMMA. © 2014 Wiley Periodicals, Inc.

Heat accumulation during sequential cortical bone drilling.

PubMed

Palmisano, Andrew C; Tai, Bruce L; Belmont, Barry; Irwin, Todd A; Shih, Albert; Holmes, James R

2016-03-01

Significant research exists regarding heat production during single-hole bone drilling. No published data exist regarding repetitive sequential drilling. This study elucidates the phenomenon of heat accumulation for sequential drilling with both Kirschner wires (K wires) and standard two-flute twist drills. It was hypothesized that cumulative heat would result in a higher temperature with each subsequent drill pass. Nine holes in a 3 × 3 array were drilled sequentially on moistened cadaveric tibia bone kept at body temperature (about 37 °C). Four thermocouples were placed at the center of four adjacent holes and 2 mm below the surface. A battery-driven hand drill guided by a servo-controlled motion system was used. Six samples were drilled with each tool (2.0 mm K wire and 2.0 and 2.5 mm standard drills). K wire drilling increased temperature from 5 °C at the first hole to 20 °C at holes 6 through 9. A similar trend was found in standard drills with less significant increments. The maximum temperatures of both tools increased from <0.5 °C to nearly 13 °C. The difference between drill sizes was found to be insignificant (P > 0.05). In conclusion, heat accumulated during sequential drilling, with size difference being insignificant. K wire produced more heat than its twist-drill counterparts. This study has demonstrated the heat accumulation phenomenon and its significant effect on temperature. Maximizing the drilling field and reducing the number of drill passes may decrease bone injury. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

Transparent model of temporal bone and vestibulocochlear organ made by 3D printing.

PubMed

Suzuki, Ryoji; Taniguchi, Naoto; Uchida, Fujio; Ishizawa, Akimitsu; Kanatsu, Yoshinori; Zhou, Ming; Funakoshi, Kodai; Akashi, Hideo; Abe, Hiroshi

2018-01-01

The vestibulocochlear organ is composed of tiny complex structures embedded in the petrous part of the temporal bone. Landmarks on the temporal bone surface provide the only orientation guide for dissection, but these need to be removed during the course of dissection, making it difficult to grasp the underlying three-dimensional structures, especially for beginners during gross anatomy classes. We report herein an attempt to produce a transparent three-dimensional-printed model of the human ear. En bloc samples of the temporal bone from donated cadavers were subjected to computed tomography (CT) scanning, and on the basis of the data, the surface temporal bone was reconstructed with transparent resin and the vestibulocochlear organ with white resin to create a 1:1.5 scale model. The carotid canal was stuffed with red cotton, and the sigmoid sinus and internal jugular vein were filled with blue clay. In the inner ear, the internal acoustic meatus, cochlea, and semicircular canals were well reconstructed in detail with white resin. The three-dimensional relationships of the semicircular canals, spiral turns of the cochlea, and internal acoustic meatus were well recognizable from every direction through the transparent surface resin. The anterior semicircular canal was obvious immediately beneath the arcuate eminence, and the topographical relationships of the vestibulocochlear organ and adjacent great vessels were easily discernible. We consider that this transparent temporal bone model will be a very useful aid for better understanding of the gross anatomy of the vestibulocochlear organ.

Retrospective study of sonographic findings in bone involvement associated with rotator cuff calcific tendinopathy: preliminary results of a case series*

PubMed Central

Nogueira-Barbosa, Marcello H.; Gregio-Junior, Everaldo; Lorenzato, Mario Muller

2015-01-01

Objective The present study was aimed at investigating bone involvement secondary to rotator cuff calcific tendonitis at ultrasonography. Materials and Methods Retrospective study of a case series. The authors reviewed shoulder ultrasonography reports of 141 patients diagnosed with rotator cuff calcific tendonitis, collected from the computer-based data records of their institution over a four-year period. Imaging findings were retrospectively and consensually analyzed by two experienced musculoskeletal radiologists looking for bone involvement associated with calcific tendonitis. Only the cases confirmed by computed tomography were considered for descriptive analysis. Results Sonographic findings of calcific tendinopathy with bone involvement were observed in 7/141 (~ 5%) patients (mean age, 50.9 years; age range, 42-58 years; 42% female). Cortical bone erosion adjacent to tendon calcification was the most common finding, observed in 7/7 cases. Signs of intraosseous migration were found in 3/7 cases, and subcortical cysts in 2/7 cases. The findings were confirmed by computed tomography. Calcifications associated with bone abnormalities showed no acoustic shadowing at ultrasonography, favoring the hypothesis of resorption phase of the disease. Conclusion Preliminary results of the present study suggest that ultrasonography can identify bone abnormalities secondary to rotator cuff calcific tendinopathy, particularly the presence of cortical bone erosion. PMID:26811551

An Active Black Hole in a Compact Dwarf

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2016-05-01

A new type of galaxy has just been added to the galaxy zoo: a small, compact, and old elliptical galaxy that shows signs of a monster black hole actively accreting material in its center. What can this unusual discovery tell us about how compact elliptical galaxies form?A New Galactic BeastCompact elliptical galaxies are an extremely rare early-type dwarf galaxy. Consistent with their name, compact ellipticals are small, very compact collections of ancient stars; these galaxies exhibit a high surface brightness and arent actively forming stars.Optical view of the ancient compact elliptical galaxy SDSS J085431.18+173730.5 (center of image) in an SDSS color composite image. [Adapted from Paudel et al. 2016]Most compact ellipticals are found in dense environments, particularly around massive galaxies. This has led astronomers to believe that compact ellipticals might form via the tidal stripping of a once-large galaxy in interactions with another, massive galaxy. In this model, once the original galaxys outer layers are stripped away, the compact inner bulge component would be left behind as a compact elliptical galaxy. Recent discoveries of a few isolated compact ellipticals, however, have strained this model.Now a new galaxy has been found to confuse our classification schemes: the first-ever compact elliptical to also display signs of an active galactic nucleus. Led by Sanjaya Paudel (Korea Astronomy and Space Science Institute), a team of scientists discovered SDSS J085431.18+173730.5 serendipitously in Sloan Digital Sky Survey data. The team used SDSS images and spectroscopy in combination with data from the Canada-France-Hawaii Telescope to learn more about this unique galaxy.Puzzling CharacteristicsSDSS J085431.18+173730.5 presents an interesting conundrum. Ancient compact ellipticals are supposed to be devoid of gas, with no fuel left to trigger nuclear activity. Yet SDSS J085431.18+173730.5 clearly shows the emission lines that indicate active accretion onto

Temperature evolution during compaction of pharmaceutical powders.

PubMed

Zavaliangos, Antonios; Galen, Steve; Cunningham, John; Winstead, Denita

2008-08-01

A numerical approach to the prediction of temperature evolution in tablet compaction is presented here. It is based on a coupled thermomechanical finite element analysis and a calibrated Drucker-Prager Cap model. This approach is capable of predicting transient temperatures during compaction, which cannot be assessed by experimental techniques due to inherent test limitations. Model predictions are validated with infrared (IR) temperature measurements of the top tablet surface after ejection and match well with experiments. The dependence of temperature fields on speed and degree of compaction are naturally captured. The estimated transient temperatures are maximum at the end of compaction at the center of the tablet and close to the die wall next to the powder/die interface.

Structure of Clavicle In Relation to Weight Transmission

PubMed Central

Routatal, Rohini V

2015-01-01

Aims and Objectives It is a known fact that weight of upper limb is transmitted to the axial skeleton through clavicle. The present study is an attempt to correlate pattern of compact and trabecular bone of clavicle as a weight transmitting bone. Materials and Methods Sixty clavicles were studied from right and left sides of 30 cadavers donated to the Anatomy department, Pramukhswami Medical College, Karamsad, India. The study was focused on the thickness of compact bone of clavicle and trabecular pattern of this bone. Results Cancellous bone: Cancellous bone near both ends of clavicle presented meshwork of thin bony plates. Between the conoid tubercle and area for attachment of costo-clavicular ligament, cancellous bone showed a definite pattern. Thickness of compact bone The compact bone was thicker between conoid tubercle and area for attachment of costo-clavicular ligament. At midshaft point thickness of compact bone was maximum. Conclusion The structure of clavicle between conoid tubercle and area for costoclavicular ligament showed thick compact bone and definite pattern of cancellous bone. This structure of clavicle between conoid tubercle and area for attachment of costo-clavicular ligament transmits weight from lateral to medial direction and this knowledge of clavicular structure will also be useful to orthopedic surgeons to deal with clavicular fractures and other abnormalities. PMID:26393112

Early Verb Constructions in French: Adjacency on the Left Edge

ERIC Educational Resources Information Center

Veneziano, Edy; Clark, Eve V.

2016-01-01

Children acquiring French elaborate their early verb constructions by adding adjacent morphemes incrementally at the left edge of core verbs. This hypothesis was tested with 2657 verb uses from four children between 1;3 and 2;7. Consistent with the Adjacency Hypothesis, children added clitic subjects frst only to present tense forms (as in…

Adjacent bin stability evaluating for feature description

NASA Astrophysics Data System (ADS)

Nie, Dongdong; Ma, Qinyong

2018-04-01

Recent study improves descriptor performance by accumulating stability votes for all scale pairs to compose the local descriptor. We argue that the stability of a bin depends on the differences across adjacent pairs more than the differences across all scale pairs, and a new local descriptor is composed based on the hypothesis. A series of SIFT descriptors are extracted from multiple scales firstly. Then the difference value of the bin across adjacent scales is calculated, and the stability value of a bin is calculated based on it and accumulated to compose the final descriptor. The performance of the proposed method is evaluated with two popular matching datasets, and compared with other state-of-the-art works. Experimental results show that the proposed method performs satisfactorily.

Chondrosarcoma of the hyoid bone - Report of a case and a literature review of the suitable treatment strategy.

PubMed

Maki, Daisuke; Mori, Taisuke; Teshima, Masanori; Kobayashi, Kenya; Matsumoto, Fumihiko; Sakai, Akihiro; Okami, Kenji; Yoshimoto, Seiichi

2017-10-01

Chondrosarcoma is a rare malignant tumor occurring in the trunk and long bones. We present an extremely rare case of chondrosarcoma of the hyoid bone with clinical and pathological correlation and a literature review. We searched all cases of the hyoid chondrosarcoma in PubMed (MEDLINE) between 1990 and 2015. Eighteen cases were analyzed, including the present case. Most of them were low grade type. In 12 cases where intraoperative findings were recorded, no adhesion to the surrounding tissue was observed. Chondrosarcoma of the hyoid bone is usually low grade type, and there may be no invasion to the adjacent structures even if invasion is suspected by imaging findings. In order to preserve swallowing and laryngeal function, total hyoidectomy without laryngectomy should be indicated according to the intraoperative findings. Needle biopsy is an effective diagnostic technique, but open biopsy should be avoided to prevent the dissemination. To the best of our knowledge, this is the first presentation of hyoid bone chondrosarcoma with the investigation of intraoperative findings and pre-operative diagnostic modality. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Numerical simulation of intelligent compaction technology for construction quality control.

DOT National Transportation Integrated Search

2014-12-01

Intelligent compaction (IC) technique is a fast-developing technology for compaction quality control and acceptance. Proof rolling using the intelligent compaction rollers after completing compaction can eectively identify : the weak spots and sig...

Silk fibroin/kappa-carrageenan composite scaffolds with enhanced biomimetic mineralization for bone regeneration applications.

PubMed

Nourmohammadi, Jhamak; Roshanfar, Fahimeh; Farokhi, Mehdi; Haghbin Nazarpak, Masoumeh

2017-07-01

The combination of protein-polysaccharide in scaffolding together with the ability to induce bone-like apatite formation has become a promising approach to mimic extracellular matrix composition. In the present study, we developed and characterized new bioactive composite scaffolds from kappa-carrageenan/silk fibroin for bone regeneration applications. Three dimensional (3D) scaffolds were fabricated by adding various amounts of carrageenan to a silk fibroin solution, followed by freeze-drying. Various characterization techniques were applied to analyze such items as the structure, morphology, compressive strength, and bone-like apatite mineralization of the composites, which were then compared to those of pure fibroin scaffolds. The results demonstrated the formation of a highly porous structure with interconnected pores. The mean pore size and porosity both increased by increasing carrageenan content. Moreover, the addition of carrageenan to silk fibroin led to the formation of a bone-like apatite layer throughout the scaffolds after 7days of soaking them in simulated body fluid. Osteoblast-like cell (MG 63) culture experiments indicated that all scaffolds are biocompatible. The cells attached well to the surfaces of all scaffolds and tended to join their adjacent cells. However, higher carrageenan content led to better cellular proliferation and higher Alkaline phosphatase expression. Copyright © 2017 Elsevier B.V. All rights reserved.

Potential for thermal damage to articular cartilage by PMMA reconstruction of a bone cavity following tumor excision: A finite element study.

PubMed

Radev, Boyko R; Kase, Jonathan A; Askew, Michael J; Weiner, Scott D

2009-05-29

Benign, giant cell tumors are often treated by intralesional excision and reconstruction with polymethylmethacrylate (PMMA) bone cement. The exothermic reaction of the in-situ polymerizing PMMA is believed to beneficially kill remaining tumor cells. However, at issue is the extent of this necrotic effect into the surrounding normal bone and the adjacent articular cartilage. Finite element analysis (ABAQUS 6.4-1) was used to determine the extent of possible thermal necrosis around prismatically shaped, PMMA implants (8-24cc in volume), placed into a peripheral, sagittally symmetric, metaphyseal defect in the proximal tibia. Temperature/exposure time conditions indicating necrotic potential during the exotherm of the polymerizing bone cement were found in regions of the cancellous bone within 3mm of the superior surface of the PMMA implant. If less than 3mm of cancellous bone existed between the PMMA implant and the subchondral bone layer, regions of the subchondral bone were also exposed to thermally necrotic conditions. However, as long as there were at least 2mm of uniform subchondral bone above the PMMA implant, the necrotic regions did not extend into the overlying articular cartilage. This was the case even when the PMMA was in direct contact with the subchondral bone. If the subchondral bone is not of sufficient thickness, or is not continuous, then care should be taken to protect the articular cartilage from thermal damage as a result of the reconstruction of the tumor cavity with PMMA bone cement.

Method for preparing porous metal hydride compacts

DOEpatents

Ron, Moshe; Gruen, Dieter M.; Mendelsohn, Marshall H.; Sheft, Irving

1981-01-01

A method for preparing porous metallic-matrix hydride compacts which can be repeatedly hydrided and dehydrided without disintegration. A mixture of a finely divided metal hydride and a finely divided matrix metal is contacted with a poison which prevents the metal hydride from dehydriding at room temperature and atmospheric pressure. The mixture of matrix metal and poisoned metal hydride is then compacted under pressure at room temperature to form porous metallic-matrix hydride compacts.

Method for preparing porous metal hydride compacts

DOEpatents

Ron, M.; Gruen, D.M.; Mendelsohn, M.H.; Sheft, I.

1980-01-21

A method for preparing porous metallic-matrix hydride compacts which can be repeatedly hydrided and dehydrided without disintegration. A mixture of a finely divided metal hydride and a finely divided matrix metal is contacted with a poison which prevents the metal hydride from dehydriding at room temperature and atmospheric pressure. The mixture of matrix metal and poisoned metal hydride is then compacted under pressure at room temperature to form porous metallic-matrix hydride compacts.

Impact Compaction of a Granular Material

NASA Astrophysics Data System (ADS)

Fenton, Gregg; Asay, Blaine; Todd, Steve; Grady, Dennis

2017-06-01

The dynamic behavior of granular materials has importance to a variety of engineering applications. Although, the mechanical behavior of granular materials have been studied extensively for several decades, the dynamic behavior of these materials remains poorly understood. High-quality experimental data are needed to improve our general understanding of granular material compaction physics. This paper describes how an instrumented plunger impact system can be used to measure the compaction process for granular materials at high and controlled strain rates and subsequently used for computational modelling. The experimental technique relies on a gas-gun driven plunger system to generate a compaction wave through a volume of granular material. This volume of material has been redundantly instrumented along the bed length to track the progression of the compaction wave, and the piston displacement is measured with Photon Doppler Velocimetry (PDV). Using the gathered experimental data along with the initial material tap density, a granular material equation of state can be determined.

Facial nerve stimulation associated with cochlear implant use following temporal bone fractures.

PubMed

Espahbodi, Mana; Sweeney, Alex D; Lennon, Kristen J; Wanna, George B

2015-01-01

To describe the incidence and management of patients with facial nerve stimulation (FNS) associated with cochlear implant (CI) use in the setting of a prior temporal bone fracture. One adult CI recipient is reported who experienced implant associated FNS with a history of a temporal bone fracture. Additionally, a literature search was performed to identify similar patients from previous descriptions of CI related FNS. Presence of FNS after implantation and ability to modify implant programming to avoid FNS. The patient in the present report experienced FNS for middle and basal electrodes during intraoperative neural response telemetry (NRT) in the absence of any surgical exposure or manipulation of the facial nerve. FNS was absent during device activation, but it recurred during follow-up programming sessions. However, additional programming has prevented further FNS during regular implant use. Four other patients with FNS after temporal bone fracture were identified from the literature, and the present case represents the one of two cases in which reprogramming allowed for implant use without FNS. CI associated FNS is uncommon in patients with a history of a temporal bone fracture, but it is likely that fracture lines provide a lower impedance pathway to the adjacent facial nerve and thus reduce the threshold for FNS. The present report suggests that, in the setting of a prior temporal bone fracture, NRT is not always a reliable predictor of FNS during implant use, and programming changes can help to mitigate FNS when it occurs. Copyright © 2015 Elsevier Inc. All rights reserved.

Objectifying the Adjacent and Opposite Angles: A Cultural Historical Analysis

ERIC Educational Resources Information Center

Daher, Wajeeh; Musallam, Nadera

2018-01-01

The angle topic is central to the development of geometric knowledge. Two of the basic concepts associated with this topic are the adjacent and opposite angles. It is the goal of the present study to analyze, based on the cultural historical semiotics framework, how high-achieving seventh grade students objectify the adjacent and opposite angles'…

Free bone graft reconstruction of irradiated facial tissue: Experimental effects of basic fibroblast growth factor stimulation

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

Eppley, B.L.; Connolly, D.T.; Winkelmann, T.

1991-07-01

A study was undertaken to evaluate the potential utility of basic fibroblast growth factor in the induction of angiogenesis and osseous healing in bone previously exposed to high doses of irradiation. Thirty New Zealand rabbits were evaluated by introducing basic fibroblast growth factor into irradiated mandibular resection sites either prior to or simultaneous with reconstruction by corticocancellous autografts harvested from the ilium. The fate of the free bone grafts was then evaluated at 90 days postoperatively by microangiographic, histologic, and fluorochrome bone-labeling techniques. Sequestration, necrosis, and failure to heal to recipient osseous margins was observed both clinically and histologically inmore » all nontreated irradiated graft sites as well as those receiving simultaneous angiogenic stimulation at the time of graft placement. No fluorescent activity was seen in these graft groups. In the recipient sites pretreated with basic fibroblast growth factor prior to placement of the graft, healing and reestablishment of mandibular contour occurred in nearly 50 percent of the animals. Active bone formation was evident at cortical margins adjacent to the recipient sites but was absent in the more central cancellous regions of the grafts.« less

Principles of control automation of soil compacting machine operating mechanism

NASA Astrophysics Data System (ADS)

Anatoly Fedorovich, Tikhonov; Drozdov, Anatoly

2018-03-01

The relevance of the qualitative compaction of soil bases in the erection of embankment and foundations in building and structure construction is given.The quality of the compactible gravel and sandy soils provides the bearing capability and, accordingly, the strength and durability of constructed buildings.It has been established that the compaction quality depends on many external actions, such as surface roughness and soil moisture; granulometry, chemical composition and degree of elasticity of originalfilled soil for compaction.The analysis of technological processes of soil bases compaction of foreign and domestic information sources showed that the solution of such important problem as a continuous monitoring of soil compaction actual degree in the process of machine operation carry out only with the use of modern means of automation. An effective vibrodynamic method of gravel and sand material sealing for the building structure foundations for various applications was justified and suggested.The method of continuous monitoring the soil compaction by measurement of the amplitudes and frequencies of harmonic oscillations on the compactible surface was determined, which allowed to determine the basic elements of facilities of soil compacting machine monitoring system of operating, etc. mechanisms: an accelerometer, a bandpass filter, a vibro-harmonics, an on-board microcontroller. Adjustable parameters have been established to improve the soil compaction degree and the soil compacting machine performance, and the adjustable parameter dependences on the overall indexhave been experimentally determined, which is the soil compaction degree.A structural scheme of automatic control of the soil compacting machine control mechanism and theoperation algorithm has been developed.

Assessing trace element diffusion models in fossil and sub-fossil bone

NASA Astrophysics Data System (ADS)

Suarez, C. A.; Kohn, M. J.

2012-12-01

Three different diffusion models have been proposed to explain trace element uptake during fossilization of bone: diffusion-adsorption (DA), diffusion-recrystallization (DR), and double-medium diffusion (DMD). Theoretically, differences in trace element profiles, particularly the rare earth elements (REE) and U, can discriminate among these possibilities. In this study, we tested which model best explains natural samples by analyzing trace element profiles in natural bone using laser-ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS). Fossil bones ranging in age from a few ka to over 100 Ma were analyzed along traverses from the outer cortical edge to the inner marrow cavity margin. Forty major, minor and trace elements were analyzed, notably Ca, P, transition metals, Sr, Ba, REE, U, Th and Pb. Spatial and analytical resolutions were ~10 μm and ~100 ppb respectively. Many specimens show commonly observed exponential decreases in REE from the outer edge and marrow cavity, with relatively homogeneous U distributions. Yet, most significantly, specimens from American Falls (last interglacial) and Duck Point (last glacial maximum) show distinctive U plateaus adjacent to the outer and inner cortical bone margins. Whereas exponential profiles can be produced by different uptake processes, such plateaus are diagnostic of a DR mechanism. Our work is consistent with recent investigation of trace element diffusivities in modern fresh and deproteinated bone. These studies show similar diffusion rates for REE and U, so the profound disparity in U vs. REE profiles in most fossils cannot result solely from differences in volume diffusion within the context of DA and DMD. Rather, as a recrystallization front propagates into bone, the bone appears to encode changing soil water compositions with earlier vs. later compositions reflected in the bone margin vs. interior. Soil water U concentrations apparently remain nearly fixed during fossilization, whereas REE are

Two Distinct Processes of Bone-like Tissue Formation by Dental Pulp Cells after Tooth Transplantation

PubMed Central

Yukita, Akira; Yoshiba, Kunihiko; Yoshiba, Nagako; Takahashi, Masafumi; Nakamura, Hiroaki

2012-01-01

Dental pulp is involved in the formation of bone-like tissue in response to external stimuli. However, the origin of osteoblast-like cells constructing this tissue and the mechanism of their induction remain unknown. We therefore evaluated pulp mineralization induced by transplantation of a green fluorescent protein (GFP)–labeled tooth into a GFP-negative hypodermis of host rats. Five days after the transplantation, the upper pulp cavity became necrotic; however, cell-rich hard tissue was observed adjacent to dentin at the root apex. At 10 days, woven bone-like tissue was formed apart from the dentin in the upper pulp. After 20 days, these hard tissues expanded and became histologically similar to bone. GFP immunoreactivity was detected in the hard tissue-forming cells within the root apex as well as in the upper pulp. Furthermore, immunohistochemical observation of α–smooth muscle actin, a marker for undifferentiated cells, showed a positive reaction in cells surrounding this bone-like tissue within the upper pulp but not in those within the root apex. Immunoreactivities of Smad4, Runx2, and Osterix were detected in the hard tissue-forming cells within both areas. These results collectively suggest that the dental pulp contains various types of osteoblast progenitors and that these cells might thus induce bone-like tissue in severely injured pulp. PMID:22899860

Compaction within the South Belridge diatomite

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

Chase C.A. Jr.; Dietrich, J.K.

1989-11-01

Compaction is incorporated into a field-scale finite-difference thermal simulator to allow practical engineering analysis of reservoir compaction caused by fluid withdrawal. Capabilities new to petroleum applications include hysteresis in the form of limited rebound during fluid injection and the concept of relaxation time (i.e., creep).

The nanometre-scale physiology of bone: steric modelling and scanning transmission electron microscopy of collagen–mineral structure

PubMed Central

Alexander, Benjamin; Daulton, Tyrone L.; Genin, Guy M.; Lipner, Justin; Pasteris, Jill D.; Wopenka, Brigitte; Thomopoulos, Stavros

2012-01-01

The nanometre-scale structure of collagen and bioapatite within bone establishes bone's physical properties, including strength and toughness. However, the nanostructural organization within bone is not well known and is debated. Widely accepted models hypothesize that apatite mineral (‘bioapatite’) is present predominantly inside collagen fibrils: in ‘gap channels’ between abutting collagen molecules, and in ‘intermolecular spaces’ between adjacent collagen molecules. However, recent studies report evidence of substantial extrafibrillar bioapatite, challenging this hypothesis. We studied the nanostructure of bioapatite and collagen in mouse bones by scanning transmission electron microscopy (STEM) using electron energy loss spectroscopy and high-angle annular dark-field imaging. Additionally, we developed a steric model to estimate the packing density of bioapatite within gap channels. Our steric model and STEM results constrain the fraction of total bioapatite in bone that is distributed within fibrils at less than or equal to 0.42 inside gap channels and less than or equal to 0.28 inside intermolecular overlap regions. Therefore, a significant fraction of bone's bioapatite (greater than or equal to 0.3) must be external to the fibrils. Furthermore, we observe extrafibrillar bioapatite between non-mineralized collagen fibrils, suggesting that initial bioapatite nucleation and growth are not confined to the gap channels as hypothesized in some models. These results have important implications for the mechanics of partially mineralized and developing tissues. PMID:22345156

The Volpe Center GPS Adjacent Band Compatibility Program Plan : GPS Adjacent Band Compatibility Workshop, Volpe Center, Cambridge MA

DOT National Transportation Integrated Search

2014-09-18

Approach to DOT GPS Adjacent Band Compatibility Assessment. Identify forums and provide public outreach to make sure the progress and work are as open and transparent as possible. Develop an implementation plan that incorporates aspects from the DOT ...

Bone tumor

MedlinePlus

Tumor - bone; Bone cancer; Primary bone tumor; Secondary bone tumor; Bone tumor - benign ... The cause of bone tumors is unknown. They often occur in areas of the bone that grow rapidly. Possible causes include: Genetic defects ...

Baryon currents in QCD with compact dimensions

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

Lucini, B.; Patella, A.; Istituto Nazionale Fisica Nucleare Sezione di Pisa, Largo Pontecorvo 3, 56126 Pisa

2007-06-15

On a compact space with nontrivial cycles, for sufficiently small values of the radii of the compact dimensions, SU(N) gauge theories coupled with fermions in the fundamental representation spontaneously break charge conjugation, time reversal, and parity. We show at one loop in perturbation theory that a physical signature for this phenomenon is a nonzero baryonic current wrapping around the compact directions. The persistence of this current beyond the perturbative regime is checked by lattice simulations.

Mechanical and chemical compaction in fine-grained shallow-water limestones.

USGS Publications Warehouse

Shinn, E.A.; Robbin, D.M.

1983-01-01

Significant mechanical compaction resulted from pressures simulating less than 305 m of burial. Increasing loads to an equivalent of more than 3400 m did not significantly increase compaction or reduce sediment core length. Chemical compaction (pressure dissolution) was detected only in sediment cores compacted to pressures greater than 3400 m of burial. These short-term experiments suggest that chemical compaction would begin at much shallower depths given geologic time. Compaction experiments that caused chemical compaction lend support to the well-established hypothesis; that cement required to produce a low-porosity/low-permeability fine-grained limestone is derived internally. Dissolution, ion diffusion, and reprecipitation are considered the most likely processes for creating significant thicknesses of dense limestone in the geologic record. Continuation of chemical compaction after significant porosity reduction necessitates expulsion of connate fluids, possibly including hydrocarbons. -from Authors

Combined static-dynamic compaction of metal powder and ceramic materials

NASA Astrophysics Data System (ADS)

Mironovs, V.; Korjakins, A.; Tatarinov, A.; Barone, E.; Glushchenkov, V.

2017-10-01

Combined static-dynamic compaction of powder material presents advantages for achievement of a higher degree of powder compaction for in dry conditions. One of possible realizations is the use of pulsed electromagnetic compaction (MPC) applied in addition to the static pre-compaction carried out by a hydraulic press. Experimental MPC equipment was used for compaction powders of SiC and Al-B with W fibers at different stages of grinding. The degree of compaction was evaluated by shock plate’s displacement at different levels and regimes of dynamic loading. The paper demonstrates feasibility of the method for compaction of the selected ceramic and metal powders and presents some quantitative data for practices.

Gradual adaptation of bone structure to aquatic lifestyle in extinct sloths from Peru

PubMed Central

Amson, Eli; de Muizon, Christian; Laurin, Michel; Argot, Christine; de Buffrénil, Vivian

2014-01-01

Non-pathological densification (osteosclerosis) and swelling (pachyostosis) of bones are the main modifications affecting the skeleton of land vertebrates (tetrapods) that returned to water. However, a precise temporal calibration of the acquisition of such adaptations is still wanting. Here, we assess the timing of such acquisition using the aquatic sloth Thalassocnus, from the Neogene of the Pisco Formation, Peru. This genus is represented by five species occurring in successive vertebrate-bearing horizons of distinct ages. It yields the most detailed data about the gradual acquisition of aquatic adaptations among tetrapods, in displaying increasing osteosclerosis and pachyostosis through time. Such modifications, reflecting a shift in the habitat from terrestrial to aquatic, occurred over a short geological time span (ca 4 Myr). Otherwise, the bones of terrestrial pilosans (sloths and anteaters) are much more compact than the mean mammalian condition, which suggests that the osteosclerosis of Thalassocnus may represent an exaptation. PMID:24621950

Limits to the use of highly compacted bentonite as a deterrent for microbiologically influenced corrosion in a nuclear fuel waste repository

NASA Astrophysics Data System (ADS)

Stroes-Gascoyne, Simcha; Hamon, Connie J.; Maak, Peter

Recent studies have suggested that microbial activity in highly compacted bentonite (⩾1600 kg/m 3) is severely suppressed. Therefore, it appears that the dry density of emplaced bentonite barriers in a geological repository for nuclear waste may be tailored such that a microbiologically unfavorable environment can be created adjacent to used fuel containers. This would ensure that microbiologically influenced corrosion is a negligible contributor to the overall corrosion process. However, this premise is valid only as long as the emplaced bentonite maintains a uniform high dry density (⩾1600 kg/m 3) because it has been shown that high dry density only suppresses microbial activity but not necessarily eliminates the viable microbial population in bentonite. In a repository, a reduction in the dry density of highly compacted bentonite may occur at a number of interface locations, such as placement gaps, contact regions with materials of different densities and contact points with water-carrying fractures in the rock. Experiments were carried out in our laboratory to examine the effects of a reduction in dry density (from 1600 kg/m 3 to about 1000 kg/m 3) on the recovery of microbial culturability in compacted bentonite. Results showed that upon expansion of compacted bentonite into a void, the resulting reduction in dry density stimulated or restored culturability of indigenous microbes. In a repository this would increase the possibility of in situ activity, which might be detrimental for the longevity of waste containers. Reductions in dry density, therefore, should be minimized or eliminated by adequate design and placement methods of compacted bentonite. Materials compliance models can be used to determine the required as-placed dry densities of bentonite buffer and gap fillings to achieve specific targets for long-term equilibrium dry densities for various container placement room designs. Locations where flowing fractures could be in contact with highly

Transplantation of stem cells from human exfoliated deciduous teeth for bone regeneration in the dog mandibular defect

PubMed Central

Behnia, Ali; Haghighat, Abbas; Talebi, Ardeshir; Nourbakhsh, Nosrat; Heidari, Fariba

2014-01-01

AIM: To investigate the effect of stem cells from human exfoliated deciduous teeth (SHED) transplanted for bone regeneration in the dog mandibular defect. METHODS: In this prospective comparative study, SHEDs had been isolated 5 years ago from human exfoliated deciduous teeth. The undifferentiated stem cells were seeded into mandibular bone through-and-through defects of 4 dogs. Similar defects in control group were filled with cell-free collagen scaffold. After 12 wk, biopsies were taken and morphometric analysis was performed. The percentage of new bone formation and foreign body reaction were measured in each case. The data were subject to statistical analysis using the Mann-Whitney U and Kruskalwalis statistical tests. Differences at P < 0.05 was considered as significant level. RESULTS: There were no significant differences between control and SHED-seeded groups in connective tissue (P = 0.248), woven bone (P = 0.248) and compact bone (P = 0.082). There were not any side effects in transplanted SHED group such as teratoma or malignancy and abnormalities in this period. CONCLUSION: SHEDs which had been isolated and characterized 5 years ago and stored with cryopreservation banking were capable of proliferation and osteogenesis after 5 years, and no immune response was observed after three months of seeded SHEDs. PMID:25258673

Do Mangroves Subsidize Carbon to Adjacent Mudflat Fish Communities?

NASA Astrophysics Data System (ADS)

Henkel, S.; Kasten, S.; Hartmann, J.; Staubwasser, M.; Hernandez, M. F.; West, L.; Midway, S. R.; Polito, M. J.

2017-12-01

Mangroves are often implicated as energetic sources for fisheries productivity. However, the validity of this connection still remains in contention. Stable isotopes may provide answers by tracking the use of specific basal carbon sources in fish and invertebrates living in mangrove-mudflat habitat mosaics. We analyzed 307 consumer samples representing n=44 fish and invertebrate species collected from mangrove forest creeks and adjacent mudflats in coastal Tanzania using bulk carbon and nitrogen stable isotope analysis. Given the proposed high productivity of mangrove habitats, we hypothesize that mudflat communities will have carbon stable isotope values similar to mangrove communities either through the flux of mangrove carbon into adjacent mudflats and/or via the movement of mudflat fish communities into and out of mangrove habitats. Alternatively, mangrove carbon is often refractory, which may result in mudflat communities with isotopic values that differ from those found in adjacent mangrove communities. This scenario would suggest limited carbon flow between mudflat and mangrove food webs and that the movement of fish into and out of mangrove habitats is related to shelter from predation more than feeding. Data analysis is ongoing to test these competing hypotheses. By understanding the contribution of mangrove carbon to adjacent habitats, managers in Tanzania can make better informed decisions regarding the protection of mangroves and the local fisheries, which are a crucial source of income and food.

Miscellaneous indications in bone scintigraphy: metabolic bone diseases and malignant bone tumors.

PubMed

Cook, Gary J R; Gnanasegaran, Gopinath; Chua, Sue

2010-01-01

The diphosphonate bone scan is ideally suited to assess many global, focal or multifocal metabolic bone disorders and there remains a role for conventional bone scintigraphy in metabolic bone disorders at diagnosis, investigation of complications, and treatment response assessment. In contrast, the role of bone scintigraphy in the evaluation of primary malignant bone tumors has reduced with the improvement of morphologic imaging, such as computed tomography and magnetic resonance imaging. However, an increasing role for (18)F-fluorodeoxyglucose positron emission tomography and positron emission tomography/computed tomography is emerging as a functional assessment at diagnosis, staging, and neoadjuvant treatment response assessment.

A 5-year prospective radiographic evaluation of marginal bone levels adjacent to parallel-screw cylinder machined-neck implants and rough-surfaced microthreaded implants using digitized panoramic radiographs.

PubMed

Nickenig, Hans-Joachim; Wichmann, Manfred; Happe, Arndt; Zöller, Joachim E; Eitner, Stephan

2013-10-01

The purpose of this split-mouth study was to compare macro- and microstructure implant surfaces at the marginal bone level over five years of functional loading. From January to February 2006, 133 implants (70 rough-surfaced microthreaded implants and 63 machined-neck implants) were inserted in the mandible of 34 patients with Kennedy Class I residual dentitions and followed until December 2011. Marginal bone level was radiographically determined at six time points: implant placement (baseline), after the healing period, after six months, and at two years, three years, and five years follow-up. Median follow-up time was 5.2 years (range: 5.1-5.4). The machined-neck group had a mean crestal bone loss of 0.5 mm (0.0-2.3) after the healing period, 1.1 mm (0.0-3.0) at two years follow-up, and 1.4 mm (0.0-2.9) at five years follow-up. The rough-surfaced microthreaded implant group had a mean bone loss of 0.1 mm (-0.4 to 2.0) after the healing period, 0.5 mm (0.0-2.1) at two years follow-up, and 0.7 mm (0.0-2.3) at five years follow-up. The two implant types showed significant differences in marginal bone levels. Rough-surfaced microthreaded design caused significantly less loss of crestal bone levels under long-term functional loading in the mandible when compared to machined-neck implants. Copyright © 2012 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

Optimally oriented grooves on dental implants improve bone quality around implants under repetitive mechanical loading.

PubMed

Kuroshima, Shinichiro; Nakano, Takayoshi; Ishimoto, Takuya; Sasaki, Muneteru; Inoue, Maaya; Yasutake, Munenori; Sawase, Takashi

2017-01-15

The aim was to investigate the effect of groove designs on bone quality under controlled-repetitive load conditions for optimizing dental implant design. Anodized Ti-6Al-4V alloy implants with -60° and +60° grooves around the neck were placed in the proximal tibial metaphysis of rabbits. The application of a repetitive mechanical load was initiated via the implants (50N, 3Hz, 1800 cycles, 2days/week) at 12weeks after surgery for 8weeks. Bone quality, defined as osteocyte density and degree of biological apatite (BAp) c-axis/collagen fibers, was then evaluated. Groove designs did not affect bone quality without mechanical loading; however, repetitive mechanical loading significantly increased bone-to-implant contact, bone mass, and bone mineral density (BMD). In +60° grooves, the BAp c-axis/collagen fibers preferentially aligned along the groove direction with mechanical loading. Moreover, osteocyte density was significantly higher both inside and in the adjacent region of the +60° grooves, but not -60° grooves. These results suggest that the +60° grooves successfully transmitted the load to the bone tissues surrounding implants through the grooves. An optimally oriented groove structure on the implant surface was shown to be a promising way for achieving bone tissue with appropriate bone quality. This is the first report to propose the optimal design of grooves on the necks of dental implants for improving bone quality parameters as well as BMD. The findings suggest that not only BMD, but also bone quality, could be a useful clinical parameter in implant dentistry. Although the paradigm of bone quality has shifted from density-based assessments to structural evaluations of bone, clarifying bone quality based on structural bone evaluations remains challenging in implant dentistry. In this study, we firstly demonstrated that the optimal design of dental implant necks improved bone quality defined as osteocytes and the preferential alignment degree of biological

Adjacent-Categories Mokken Models for Rater-Mediated Assessments

PubMed Central

Wind, Stefanie A.

2016-01-01

Molenaar extended Mokken’s original probabilistic-nonparametric scaling models for use with polytomous data. These polytomous extensions of Mokken’s original scaling procedure have facilitated the use of Mokken scale analysis as an approach to exploring fundamental measurement properties across a variety of domains in which polytomous ratings are used, including rater-mediated educational assessments. Because their underlying item step response functions (i.e., category response functions) are defined using cumulative probabilities, polytomous Mokken models can be classified as cumulative models based on the classifications of polytomous item response theory models proposed by several scholars. In order to permit a closer conceptual alignment with educational performance assessments, this study presents an adjacent-categories variation on the polytomous monotone homogeneity and double monotonicity models. Data from a large-scale rater-mediated writing assessment are used to illustrate the adjacent-categories approach, and results are compared with the original formulations. Major findings suggest that the adjacent-categories models provide additional diagnostic information related to individual raters’ use of rating scale categories that is not observed under the original formulation. Implications are discussed in terms of methods for evaluating rating quality. PMID:29795916

Li-S batteries: Firing for compactness

NASA Astrophysics Data System (ADS)

Li, Yanguang; Chen, Fengjiao

2017-07-01

Conventional Li-S batteries have a non-compact cathode structure containing low areal loading of active materials. Now, a strategy of burning Li foils in a CS2 vapour is presented, which leads to the formation of highly compact Li2S nanoparticles as a lithiated sulfur cathode, offering promising battery performance.

Fabrication method, structure, mechanical, and biological properties of decellularized extracellular matrix for replacement of wide bone tissue defects.

PubMed

Anisimova, N Y; Kiselevsky, M V; Sukhorukova, I V; Shvindina, N V; Shtansky, D V

2015-09-01

The present paper was focused on the development of a new method of decellularized extracellular matrix (DECM) fabrication via a chemical treatment of a native bone tissue. Particular attention was paid to the influence of chemical treatment on the mechanical properties of native bones, sterility, and biological performance in vivo using the syngeneic heterotopic and orthotopic implantation models. The obtained data indicated that after a chemical decellularization treatment in 4% aqueous sodium chlorite, no noticeable signs of the erosion of compact cortical bone surface or destruction of trabeculae of spongy bone in spinal channel were observed. The histological studies showed that the chemical treatment resulted in the decellularization of both bone and cartilage tissues. The DECM samples demonstrated no signs of chemical and biological degradation in vivo. Thorough structural characterization revealed that after decellularization, the mineral frame retained its integrity with the organic phase; however clotting and destruction of organic molecules and fibers were observed. FTIR studies revealed several structural changes associated with the destruction of organic molecules, although all organic components typical of intact bone were preserved. The decellularization-induced structural changes in the collagen constituent resulted changed the deformation under compression mechanism: from the major fracture by crack propagation throughout the sample to the predominantly brittle fracture. Although the mechanical properties of radius bones subjected to decellularization were observed to degrade, the mechanical properties of ulna bones in compression and humerus bones in bending remained unchanged. The compressive strength of both the intact and decellularized ulna bones was 125-130 MPa and the flexural strength of humerus bones was 156 and 145 MPa for the intact and decellularized samples, respectively. These results open new avenues for the use of DECM samples as

Bone scan in metabolic bone diseases. Review.

PubMed

Abdelrazek, Saeid; Szumowski, Piotr; Rogowski, Franciszek; Kociura-Sawicka, Agnieszka; Mojsak, Małgorzata; Szorc, Małgorzata

2012-08-25

Metabolic bone disease encompasses a number of disorders that tend to present a generalized involvement of the whole skeleton. The disorders are mostly related to increased bone turnover and increased uptake of radiolabelled diphosphonate. Skeletal uptake of 99mTc-labelled diphosphonate depends primarily upon osteoblastic activity, and to a lesser extent, skeletal vascularity. A bone scan image therefore presents a functional display of total skeletal metabolism and has valuable role to play in the assessment of patients with metabolic bone disorders. However, the bone scan appearances in metabolic bone disease are often non-specific, and their recognition depends on increased tracer uptake throughout the whole skeleton. It is the presence of local lesions, as in metastatic disease, that makes a bone scan appearance obviously abnormal. In the early stages, there will be difficulty in evaluating the bone scans from many patients with metabolic bone disease. However, in the more severe cases scan appearances can be quite striking and virtually diagnostic.

A soluble bone morphogenetic protein type IA receptor increases bone mass and bone strength

PubMed Central

Baud’huin, Marc; Solban, Nicolas; Cornwall-Brady, Milton; Sako, Dianne; Kawamoto, Yoshimi; Liharska, Katia; Lath, Darren; Bouxsein, Mary L.; Underwood, Kathryn W.; Ucran, Jeffrey; Kumar, Ravindra; Pobre, Eileen; Grinberg, Asya; Seehra, Jasbir; Canalis, Ernesto; Pearsall, R. Scott; Croucher, Peter I.

2012-01-01

Diseases such as osteoporosis are associated with reduced bone mass. Therapies to prevent bone loss exist, but there are few that stimulate bone formation and restore bone mass. Bone morphogenetic proteins (BMPs) are members of the TGFβ superfamily, which act as pleiotropic regulators of skeletal organogenesis and bone homeostasis. Ablation of the BMPR1A receptor in osteoblasts increases bone mass, suggesting that inhibition of BMPR1A signaling may have therapeutic benefit. The aim of this study was to determine the skeletal effects of systemic administration of a soluble BMPR1A fusion protein (mBMPR1A–mFc) in vivo. mBMPR1A–mFc was shown to bind BMP2/4 specifically and with high affinity and prevent downstream signaling. mBMPR1A–mFc treatment of immature and mature mice increased bone mineral density, cortical thickness, trabecular bone volume, thickness and number, and decreased trabecular separation. The increase in bone mass was due to an early increase in osteoblast number and bone formation rate, mediated by a suppression of Dickkopf-1 expression. This was followed by a decrease in osteoclast number and eroded surface, which was associated with a decrease in receptor activator of NF-κB ligand (RANKL) production, an increase in osteoprotegerin expression, and a decrease in serum tartrate-resistant acid phosphatase (TRAP5b) concentration. mBMPR1A treatment also increased bone mass and strength in mice with bone loss due to estrogen deficiency. In conclusion, mBMPR1A–mFc stimulates osteoblastic bone formation and decreases bone resorption, which leads to an increase in bone mass, and offers a promising unique alternative for the treatment of bone-related disorders. PMID:22761317

[Complications of percutaneous kyphoplasty non-related with bone leakage in treating osteoporotic thoracolumbar vertebral compression fractures].

PubMed

Ru, Xuan-liong; Jiang, Zeng-hui; Gui, Xian-ge; Sun, Qi-cai; Song, Bo-Shan; Lin, Hang; He, Jian

2015-08-01

To analyze the complications of percutaneous kyphoplasty except bone leakge for the treatment of osteoporotic thoracolumbar vertebral compression fractures. From October 2008 to October 2012,178 patients with 224 osteoporotic vertebral compression fractures were treated with percutaneous kyphoplasty under local anethsia. There were 72 males and 106 females,ranging in age from 58 to 92 years old,with an average of 75.3 years,including 93 thoracic vertebrae and 131 lumbar vertebrae. The complications except bone cement leakage were analyzed during operation and after operation. All operations were successful and all patients were followed up from 12 to 60 months with an average of 26.2 months. No death was found. Bone cement leakage occurred in 27 cases, about 15.1% in 178 cases; and complications except bone cement leakage occurred in 15 cases. There was 1 case with cardiac arrest,was completely recovery by cardiopulmonary resuscitation (CPR) immediately; and 1 case with temporary absence of breathing,was recovery after treatment. There were 3 cases with fall of blood pressure and slower of heart rate; 1 case with intestinal obstruction; 2 cases with local hematoma and 1 case with intercostal neuralgia. Vertebral body fractures of 2 cases were split by bone cement and the fractures of adjacent body occurred in 4 cases. It's uncommon complication except bone cement leakge in treatment of osteoporotic thoracolumbar vertebral compression fractures with percutaneous kyphoplasty. The complication of cardiopulmonary system is a high risk in surgery; and cytotoxicity of bone cement,nervous reflex,fat embolism and alteration of intravertebral pressure may be main reasons.

Micro-CT evaluation and histological analysis of screw-bone interface of expansive pedicle screw in osteoporotic sheep.

PubMed

Wan, Shi-yong; Lei, Wei; Wu, Zi-xiang; Lv, Rong; Wang, Jun; Fu, Suo-chao; Li, Bo; Zhan, Ce

2008-04-01

To investigate the properties of screw-bone interface of expansive pedicle screw (EPS) in osteoporotic sheep by micro-CT and histological observation. Six female sheep with bilateral ovariectomy-induced osteoporosis were employed in this experiment. After EPS insertion in each femoral condyle, the sheep were randomly divided into two groups: 3 sheep were bred for 3 months (Group A), while the other 3 were bred for 6 months (Group B). After the animals being killed, the femoral condyles with EPS were obtained, which were three-dimensionally-imaged and reconstructed by micro-CT. Histological evaluation was made thereafter. The trabecular microstructure was denser at the screw-bone interface than in the distant parts in expansive section, especially within the spiral marking. In the non-expansive section, however, there was no significant difference between the interface and the distant parts. The regions of interest (ROI) adjacent to EPS were reconstructed and analyzed by micro-CT with the same thresholds. The three-dimensional (3-D) parameters, including tissue mineral density (TMD), bone volume fraction (BVF, BV/TV), bone surface/bone volume (BS/BV) ratio, trabecular thickness (Tb.Th), and trabecular separation (Tb.Sp), were significantly better in expansive sections than non-expansive sections (P less than 0.05). Histologically, newly-formed bony trabeculae crawled along the expansive fissures and into the center of EPS. The newly-formed bones, as well as the bones at the bone-screw interface, closely contacted with the EPS and constructed four compartments. The findings of the current study, based on micro-CT and histological evaluation, suggest that EPS can significantly provide stabilization in osteoporotic cancellous bones.

Modeling Firn Compaction in Dynamic Regions

NASA Astrophysics Data System (ADS)

Horlings, Annika N.; Christianson, Knut; Waddington, Edwin D.; Stevens, C. Max; Holschuh, Nicholas

2017-04-01

Firn compaction remains the largest source of uncertainty in assessments of ice-sheet mass balance from repeat altimetry measurements due to our limited understanding of the physical processes responsible for the transformation of snow into ice. In addition to the lack of a comprehensive, physically-based constitutive relationship that describes firn compaction, dynamic thinning is an important process in some regions, but is generally neglected in firn-compaction models due to their one-dimensional nature. Here, we report on preliminary results incorporating dynamic strain thinning into firn compaction models. Using a Lagrangian (material-following) reference frame, we first compact each firn element using a standard 1-D firn-compaction model without longitudinal strain. Then, we stretch each firn parcel at each time step by applying a prescribed longitudinal strain rate in the absence of further density changes; this produces additional vertical thinning. To assess variations among firn models, we compare results from eight firn densification models currently included in the UW Community Firn Model. We focus on the Northeast Greenland Ice Stream due to the high extensile strain rates (10-3 yr-1 or higher) in the ice stream's shear margins and the extensive firn-density data in this area from seismic measurements and shallow firn/ice cores. For temperatures and accumulation rates typical for northeast Greenland, our preliminary results indicate up to an 18-meter decrease in bubble close-off depth in the shear margins compared to nearby areas either inside or outside the ice stream, which compares favorably to field data. Further work includes incorporating physically-based constitutive relations and applying these improved models to other dynamic regions, such as the Amundsen Sea Embayment, where dynamic strain thinning has accelerated in recent decades.

Explaining compact groups as change alignments

NASA Technical Reports Server (NTRS)

Mamon, Gary A.

1990-01-01

The physical nature of the apparently densest groups of galaxies, known as compact groups is a topic of some recent controversy, despite the detailed observations of a well-defined catalog of 100 isolated compact groups compiled by Hickson (1982). Whereas many authors have espoused the view that compact groups are bound systems, typically as dense as they appear in projection on the sky (e.g., Williams & Rood 1987; Sulentic 1987; Hickson & Rood 1988), others see them as the result of chance configurations within larger systems, either in 1D (chance alignments: Mamon 1986; Walke & Mamon 1989), or in 3D (transient cores: Rose 1979). As outlined in the companion review to this contribution (Mamon, in these proceedings), the implication of Hickson's compact groups (HCGs) being dense bound systems is that they would then constitute the densest isolated systems of galaxies in the Universe and the privileged site for galaxy interactions. In a previous paper (Mamon 1986), the author reviewed the arguments given for the different theories of compact groups. Since then, a dozen papers have been published on the subject, including a thorough and perceptive review by White (1990), thus more than doubling the amount written on the subject. Here, the author first enumerates the arguments that he brought up in 1986 substantiating the chance alignment hypothesis, then he reviews the current status of the numerous recent arguments arguing against chance alignments and/or for the bound dense group hypothesis (both for the majority of HCGs but not all of them), and finally he reconsiders each one of these anti-chance alignment arguments and shows that, rather than being discredited, the chance alignment hypothesis remains a fully consistent explanation for the nature of compact groups.

Compact, Low-Profile Power Converters: Highly-Laminated, High-Saturation-Flux-Density, Magnetic Cores for On-Chip Inductors in Power Converter Applications

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

None

2010-09-01

ADEPT Project: Georgia Tech is creating compact, low-profile power adapters and power bricks using materials and tools adapted from other industries and from grid-scale power applications. Adapters and bricks convert electrical energy into useable power for many types of electronic devices, including laptop computers and mobile phones. These converters are often called wall warts because they are big, bulky, and sometimes cover up an adjacent wall socket that could be used to power another electronic device. The magnetic components traditionally used to make adapters and bricks have reached their limits; they can't be made any smaller without sacrificing performance. Georgiamore » Tech is taking a cue from grid-scale power converters that use iron alloys as magnetic cores. These low-cost alloys can handle more power than other materials, but the iron must be stacked in insulated plates to maximize energy efficiency. In order to create compact, low-profile power adapters and bricks, these stacked iron plates must be extremely thin-only hundreds of nanometers in thickness, in fact. To make plates this thin, Georgia Tech is using manufacturing tools used in microelectromechanics and other small-scale industries.« less

Strategy Guideline. Compact Air Distribution Systems