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Sample records for annulus fibrosus cells

  1. Role of calcium signaling in down-regulation of aggrecan induced by cyclic tensile strain in annulus fibrosus cells

    Institute of Scientific and Technical Information of China (English)

    GUO Zhi-liang; ZHOU Yue; LI Hua-zhuang; CAO Guo-yong; TENG Hai-jun

    2006-01-01

    Objective:To study the role of intracellular calcium signal pathway in the down-regulation of aggrecan induced by cyclic tensile strain in the annulus fibrosus cells. Methods :The expression of aggrecan mRNA and core protein were respectively detected with RT-PCR and western blot after the channels transmitting calcium ions were blocked with EGTA, gadolinium and verapamil. Results:EGTA, gadolinium and verapamil partially prevented the effects of cyclic tensile strain on the expression of aggrecan in annulus fibrosus cells. Conclusion:The calcium signaling is involved in the down-regulation of proteoglycan resulting from cyclic tensile strain in the annulus fibrosus cells.

  2. Photobiomodulation on human annulus fibrosus cells during the intervertebral disk degeneration: extracellular matrix-modifying enzymes.

    Science.gov (United States)

    Hwang, Min Ho; Kim, Kyoung Soo; Yoo, Chang Min; Shin, Jae Hee; Nam, Hyo Geun; Jeong, Jin Su; Kim, Joo Han; Lee, Kwang Ho; Choi, Hyuk

    2016-05-01

    Destruction of extracellular matrix (ECM) leads to degeneration of the intervertebral disk (IVD), which is a major contributor to many spine disorders. IVD degeneration is induced by pro-inflammatory cytokines, such as tumor necrosis factor-alpha (TNF-α) and interleukin-1 beta (IL-1β), which are secreted by immune cells, including macrophages and neutrophils. The cytokines modulate ECM-modifying enzymes such as matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) in human annulus fibrosus (AF) cells. The resulting imbalance in catabolic and anabolic enzymes can cause generalized back, neck, and low back pain (LBP). Photobiomodulation (PBM) is known to regulate inflammatory responses and wound healing. The aim of this study was to mimic the degenerative IVD microenvironment, and to investigate the effect of a variety of PBM conditions (wavelength: 635, 525, and 470 nm; energy density: 16, 32, and 64 J/cm(2)) on the production of ECM-modifying-enzymes by AF cells under degenerative conditions induced by macrophage-conditioned medium (MCM), which contains pro-inflammatory cytokines such as TNF-α and IL-β secreted by macrophage during the development of intervertebral disk inflammation. We showed that the MCM-stimulated AF cells express imbalanced ratios of TIMPs (TIMP-1 and TIMP-2) and MMPs (MMP-1 and MMP-3). PBM selectively modulated the production of ECM-modifying enzymes in AF cells. These results suggest that PBM can be a therapeutic tool for degenerative IVD disorders.

  3. A novel culture platform for fast proliferation of human annulus fibrosus cells.

    Science.gov (United States)

    Xiao, Li; Ding, Mengmeng; Saadoon, Osama; Vess, Eric; Fernandez, Andrew; Zhao, Ping; Jin, Li; Li, Xudong

    2017-02-01

    Tissue engineering provides a promising approach to treat degenerative disc disease, which usually requires a large quantity of seed cells. A simple and reliable in vitro culture system to expand seed cells in a timely fashion is necessary to implement the application clinically. Here, we sought to establish a cost-effective culture system for expanding human annulus fibrosus cells using extracellular matrix (ECM) proteins as culture substrates. Cells were cultured onto a plastic surface coated with various types of ECMs, including fibronectin, vitronectin, collagen type I, gelatin and cell-free matrix deposited by human nucleus pulposus cells. AF cell morphology, growth, adhesion and phenotype (anabolic and catabolic markers) were assessed by microscopy, real-time RT-PCR, western blotting, zymography, immunofluorescence staining and biochemical assays. Fibronectin, collagen and gelatin promoted cell proliferation and adhesion in a dose-dependent manner. Fibronectin elevated mRNA expression of proteoglycan and enhanced glycosaminoglycan production. Both collagen and gelatin increased protein expression of type II collagen. Consistent with increased cell adhesion, collagen and fibronectin promoted formation of focal adhesion complexes in the cell-matrix junction, suggesting enhanced binding of the actin network with both ECM substrates. On the other hand, fibronectin, collagen and gelatin decreased expression of matrix metalloproteinase-2 and matrix metalloproteinase-9 in media. Finally, a mixture of fibronectin (1.7 μg/mL) and collagen (1.3 μg/mL) was identified as the most promising in vitro culture substrate system in promoting proliferation and maintaining anabolic-catabolic balance. Our method provides a simple and cost-effective platform for tissue engineering applications in intervertebral disc research.

  4. INTERLEUKIN-6 PROTECTS ANNULUS FIBROSUS CELL FROM APOPTOSIS INDUCED BY INTERLEUKIN-1 IN VITRO

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Objective To investigate the effect of interleukin-6 (IL-6) on the apoptosis of annulus fibrosus (AF) cell induced by interleukin-1 β (IL-1 β).Methods Cultured AF cells were divided into 6 groups and treated with no drug, 10 ng/mL IL-6, 10 ng/mL IL1β, 10 ng/mL IL-1β and Z-VAD-FMK (a caspase-9 inhibitor), 10 ng/mL IL-1β and 10 ng/mL IL-6, 10 ng/mL IL-1β and 100 ng/mL IL-6, respectively. After three days of culture, the apoptosis rate, the positive rates of caspase3, -8, and -9 of AF cells were detected with flow cytometry.Results The apoptosis rates of cells in group 1 to 6 were 2. 67%±1.08%, 2.71%±0.53%, 20.37%±1.57%, 11.34%±0.67%, 18.17%±0.74%, and 9.42%±1.08%, respectively. There was no significant difference between group 1 and 2, while the apoptosis rates of group 4, 5, and 6 were significantly lower than group 3 (P=0.001, P=0.172, and P=0.001, respectively). Positive rates of caspase-3 in group 5 (12.35%± 0.64%) and 6(9.26%±0.36%) were significantly lower than group 3 (17.14%±0.72%; P=0.001 and P<0.001, respectively). And positive rates of caspase-9 in group 5 (15.13%±1.45%) and 6 (10.17%±2.50%) were significantly lower than group 3 (19.4%±0.98%;P=0.014 and P=0.004, respectively). But there was not obvious change of caspase-8 activity after IL-6 was added.Conclusion IL-6 is capable of protecting AF cells from IL-1 β induced apoptosis in vitro. Mechanism of the protection is related with the inhibition of caspase-3 and -9 activities.

  5. Characterization of mechanics and cytocompatibility of fibrin-genipin annulus fibrosus sealant with the addition of cell adhesion molecules.

    Science.gov (United States)

    Guterl, Clare C; Torre, Olivia M; Purmessur, Devina; Dave, Khyati; Likhitpanichkul, Morakot; Hecht, Andrew C; Nicoll, Steven B; Iatridis, James C

    2014-09-01

    There is an unmet clinical need for a biomaterial sealant capable of repairing small annulus fibrosus (AF) defects. Causes of these defects include painful intervertebral disc herniations, microdiscectomy procedures, morbidity associated with needle puncture injury from discography, and future nucleus replacement procedures. This study describes the enhancements of a fibrin gel through genipin crosslinking (FibGen) and the addition of the cell adhesion molecules (CAMs), fibronectin and collagen. The gel's performance as a potential AF sealant is assessed using a series of in vitro tests. FibGen gels with CAMs had equivalent adhesive strength, gene expression, cytomorphology, and cell proliferation as fibrin alone. However, FibGen gels had enhanced material behaviors that were tunable to higher shear stiffness values and approximated human annulus tissue as compared with fibrin alone, were more dimensionally stable, and had a slower in vitro degradation rate. Cytomorphology of human AF cells cultured on FibGen gels exhibited increased elongation compared with fibrin alone, and the addition of CAMs to FibGen did not significantly affect elongation. This FibGen gel offers the promise of being used as a sealant material to repair small AF defects or to be used in combination with other biomaterials as an adhesive for larger defects.

  6. Three-dimensional development of tensile pre-strained annulus fibrosus cells for tissue regeneration: An in-vitro study

    Energy Technology Data Exchange (ETDEWEB)

    Chuah, Yon Jin [School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, Singapore 637459 (Singapore); Lee, Wu Chean [University Hospital Conventry & Warwickshire NHS Trust, Clifford Bridge Road, West Midlands CV2, 2DX (United Kingdom); Wong, Hee Kit [Department of Orthopedic Surgery, National University Health System, NUHS Tower Block Level 11, 1E Kent Ridge Road, Singapore 119228 (Singapore); Kang, Yuejun, E-mail: yuejun.kang@ntu.edu.sg [School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, Singapore 637459 (Singapore); Hee, Hwan Tak, E-mail: HTHee@ntu.edu.sg [School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, Singapore 637459 (Singapore); Pinnacle Spine & Scoliosis Centre, 3 Mount Elizabeth, Mount Elizabeth Medical Centre, #04-07, Singapore 228510 (Singapore); School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637459 (Singapore)

    2015-02-01

    Prior research has investigated the immediate response after application of tensile strain on annulus fibrosus (AF) cells for the past decade. Although mechanical strain can produce either catabolic or anabolic consequences to the cell monolayer, little is known on how to translate these findings into further tissue engineering applications. Till to date, the application and effect of tensile pre-strained cells to construct a three-dimensional (3D) AF tissue remains unknown. This study aims to investigate the effect of tensile pre-strained exposure of 1 to 24 h on the development of AF pellet culture for 3 weeks. Equibiaxial cyclic tensile strain was applied on AF monolayer cells over a period of 24 h, which was subsequently developed into a cell pellet. Investigation on cellular proliferation, phenotypic gene expression, and histological changes revealed that tensile pre-strain for 24 h had significant and lasting effect on the AF tissue development, with enhanced cell proliferation, and up-regulation of collagen type I, II, and aggrecan expression. Our results demonstrated the regenerative ability of AF cell pellets subjected to 24 h tensile pre-straining. Knowledge on the effects of tensile pre-strain exposure is necessary to optimize AF development for tissue reconstruction. Moreover, the tensile pre-strained cells may further be utilized in either cell therapy to treat mild disc degeneration disease, or the development of a disc construct for total disc replacement. - Highlights: • Establishment of tensile pre-strained cell line population for annulus development. • Tensile strain limits collagen gene expression declination in monolayer culture. • Tensile pre-strained cells up-regulate their matrix protein in 3D pellet culture.

  7. Comparison of phenotype characteristics of rat annulus fibrosus cells cultured on flexible silicone membrane and in plastic plate

    Institute of Scientific and Technical Information of China (English)

    GUO Zhi-liang; CHENG Min; CAO Guo-yong; LI Hua-zhuang; TENG Hai-jun; ZHOU Yue

    2006-01-01

    Objective:To compare the phenotype characteristics of rat annulus fibrosus (AF) cells cultured on flexible silicone membranes and those in plastic plates. Methods :The morphology of AF cells cultured in different substrates was examined. Proteoglycan was stained by toluidine blue. Contents of collagen type I , collagen type Ⅱ and aggrecan mRNAs were determined by reverse transcription-polymerase chain reaction (RT-PCR). The expression of integrin β1 was monitored by flow cytometry. By using propidium iodide (PI), the cell cycle in AF cells was analyzed. Cell adhesion to silicone membrane was also measured. Results:The AF cells cultured on different substrates were morphologically undistinguishable.Toluidine blue staining showed that there was also no difference between AF cells cultured on these 2 substrates. They still had the same expression levels of collagen type Ⅰ , collagen type Ⅱ , aggrecan mRNAs,and integrin β1. No significant difference was observed in the distribution of the cell cycle. AF cells grew well on silicone membrane. Conclusion:AF cells cultured on flexible silicone membrane maintain the stability of phenotype and may be appropriate for further studying the metabolic responses to mechanical stimuli at the cellular level.

  8. Do mechanical strain and TNF-α interact to amplify pro-inflammatory cytokine production in human annulus fibrosus cells?

    Science.gov (United States)

    Likhitpanichkul, Morakot; Torre, Olivia M; Gruen, Jadry; Walter, Benjamin A; Hecht, Andrew C; Iatridis, James C

    2016-05-03

    During intervertebral disc (IVD) injury and degeneration, annulus fibrosus (AF) cells experience large mechanical strains in a pro-inflammatory milieu. We hypothesized that TNF-α, an initiator of IVD inflammation, modifies AF cell mechanobiology via cytoskeletal changes, and interacts with mechanical strain to enhance pro-inflammatory cytokine production. Human AF cells (N=5, Thompson grades 2-4) were stretched uniaxially on collagen-I coated chambers to 0%, 5% (physiological) or 15% (pathologic) strains at 0.5Hz for 24h under hypoxic conditions with or without TNF-α (10ng/mL). AF cells were treated with anti-TNF-α and anti-IL-6. ELISA assessed IL-1β, IL-6, and IL-8 production and immunocytochemistry measured F-actin, vinculin and α-tubulin in AF cells. TNF-α significantly increased AF cell pro-inflammatory cytokine production compared to basal conditions (IL-1β:2.0±1.4-84.0±77.3, IL-6:10.6±9.9-280.9±214.1, IL-8:23.9±26.0-5125.1±4170.8pg/ml for basal and TNF-α treatment, respectively) as expected, but mechanical strain did not. Pathologic strain in combination with TNF-α increased IL-1β, and IL-8 but not IL-6 production of AF cells. TNF-α treatment altered F-actin and α-tubulin in AF cells, suggestive of altered cytoskeletal stiffness. Anti-TNF-α (infliximab) significantly inhibited pro-inflammatory cytokine production while anti-IL-6 (atlizumab) did not. In conclusion, TNF-α altered AF cell mechanobiology with cytoskeletal remodeling that potentially sensitized AF cells to mechanical strain and increased TNF-α-induced pro-inflammatory cytokine production. Results suggest an interaction between TNF-α and mechanical strain and future mechanistic studies are required to validate these observations.

  9. Beta1 integrin inhibits apoptosis induced by cyclic stretch in annulus fibrosus cells via ERK1/2 MAPK pathway.

    Science.gov (United States)

    Zhang, Kai; Ding, Wei; Sun, Wei; Sun, Xiao-jiang; Xie, You-zhuan; Zhao, Chang-qing; Zhao, Jie

    2016-01-01

    Low back pain is associated with intervertebral disc degeneration (IVDD) due to cellular loss through apoptosis. Mechanical factors play an important role in maintaining the survival of the annulus fibrosus (AF) cells and the deposition of extracellular matrix. However, the mechanisms that excessive mechanical forces lead to AF cell apoptosis are not clear. The present study was to look for how AF cells sense mechanical changes. In vivo experiments, the involvement of mechanoreceptors in apoptosis was examined by RT-PCR and/or immunoblotting in the lumbar spine of rats subjected to unbalanced dynamic and static forces. In vitro experiments, we investigated apoptotic signaling pathways in untransfected and transfected AF cells with the lentivirus vector for rat β1 integrin overexpression after cyclic stretch. Apoptosis in AF cells was assessed using flow cytometry, Hoechst 33258 nuclear staining. Western blotting was used to analyze expression of β1 integrin and caspase-3 and ERK1/2 MAPK signaling molecules. In the rat IVDD model, unbalanced dynamic and static forces induced apoptosis of disc cells, which corresponded to decreased expression of β1 integrin. Cyclic stretch-induced apoptosis in rat AF cells correlated with the activation of caspase-3 and with decreased levels of β1 integrin and the phosphorylation levels of ERK1/2 activation level. However, the overexpression of β1 integrin in AF cells ameliorated cyclic stretch-induced apoptosis and decreased caspase-3 activation. Furthermore, ERK1/2-specific inhibitor promotes apoptosis in vector β1-infected AF cells. These results suggest that the disruption of β1 integrin signaling may underlie disc cell apoptosis induced by mechanical stress. Further work is necessary to fully elucidate the pathophysiological mechanisms that underlie IVDD caused by unbalanced dynamic and static forces.

  10. Mechanisms for mechanical damage in the intervertebral disc annulus fibrosus.

    Science.gov (United States)

    Iatridis, J C James C; ap Gwynn, Iolo

    2004-08-01

    Intervertebral disc degeneration results in disorganization of the laminate structure of the annulus that may arise from mechanical microfailure. Failure mechanisms in the annulus were investigated using composite lamination theory and other analyses to calculate stresses in annulus layers, interlaminar shear stress, and the region of stress concentration around a fiber break. Scanning electron microscopy (SEM) was used to evaluate failure patterns in the annulus and evaluate novel structural features of the disc tissue. Stress concentrations in the annulus due to an isolated fiber break were localized to approximately 5 microm away from the break, and only considered a likely cause of annulus fibrosus failure (i.e., radial tears in the annulus) under extreme loading conditions or when collagen damage occurs over a relatively large region. Interlaminar shear stresses were calculated to be relatively large, to increase with layer thickness (as reported with degeneration), and were considered to be associated with propagation of circumferential tears in the annulus. SEM analysis of intervertebral disc annulus fibrosus tissue demonstrated a clear laminate structure, delamination, matrix cracking, and fiber failure. Novel structural features noted with SEM also included the presence of small tubules that appear to run along the length of collagen fibers in the annulus and a distinct collagenous structure representative of a pericellular matrix in the nucleus region.

  11. Hyperelastic anisotropic microplane constitutive model for annulus fibrosus.

    Science.gov (United States)

    Caner, Ferhun C; Guo, Zaoyang; Moran, Brian; Bazant, Zdenek P; Carol, Ignacio

    2007-10-01

    In a recent paper, Peng et al. (2006, "An Anisotropic Hyperelastic Constitutive Model With Fiber-Matrix Interaction for the Human Annulus Fibrosis," ASME J. Appl. Mech., 73(5), pp. 815-824) developed an anisotropic hyperelastic constitutive model for the human annulus fibrosus in which fiber-matrix interaction plays a crucial role in simulating experimental observations reported in the literature. Later, Guo et al. (2006, "A Composites-Based Hyperelastic Constitutive Model for Soft Tissue With Application to the Human Fibrosis," J. Mech. Phys. Solids, 54(9), pp. 1952-1971) used fiber reinforced continuum mechanics theory to formulate a model in which the fiber-matrix interaction was simulated using only composite effect. It was shown in these studies that the classical anisotropic hyperelastic constitutive models for soft tissue, which do not account for this shear interaction, cannot accurately simulate the test data on human annulus fibrosus. In this study, we show that the microplane model for soft tissue developed by Caner and Carol (2006, "Microplane Constitutive Model and Computational Framework for Blood Vessel Tissue," ASME J. Biomech. Eng., 128(3), pp. 419-427) can be adjusted for human annulus fibrosus and the resulting model can accurately simulate the experimental observations without explicit fiber-matrix interaction because, in microplane model, the shear interaction between the individual fibers distributed in the tissue provides the required additional rigidity to explain these experimental facts. The intensity of the shear interaction between the fibers can be adjusted by adjusting the spread in the distribution while keeping the total amount of the fiber constant. A comparison of results obtained from (i) a fiber-matrix parallel coupling model, which does not account for the fiber-matrix interaction, (ii) the same model but enriched with fiber-matrix interaction, and (iii) microplane model for soft tissue adapted to annulus fibrosus with two

  12. Injectable, high-density collagen gels for annulus fibrosus repair: An in vitro rat tail model.

    Science.gov (United States)

    Borde, Brandon; Grunert, Peter; Härtl, Roger; Bonassar, Lawrence J

    2015-08-01

    A herniated intervertebral disc often causes back pain when disc tissue is displaced through a damaged annulus fibrosus. Currently, the only methods available for annulus fibrosus repair involve mechanical closure of defect, which does little to address biological healing in the damaged tissue. Collagen hydrogels are injectable and have been used to repair annulus defects in vivo. In this study, high-density collagen hydrogels at 5, 10, and 15 mg/mL were used to repair defects made to intact rat caudal intervertebral discs in vitro. A group of gels at 15 mg/mL were also cross-linked with riboflavin at 0.03 mM, 0.07 mM, or 0.10 mM. These cross-linked, high-density collagen gels maintained their presence in the defect under loading and contributed positively to the mechanical response of damaged discs. Discs exhibited increases to 95% of undamaged effective equilibrium and instantaneous moduli as well as up to fourfold decreases in effective hydraulic permeability from the damaged discs. These data suggest that high-density collagen gels may be effective at restoring mechanical function of injured discs as well as potential vehicles for the delivery of biological agents such as cells or growth factors that may aid in the repair of the annulus fibrosus.

  13. The effect of the fibre orientation of electrospun scaffolds on the matrix production of rabbit annulus fibrosus-derived stem cells

    Institute of Scientific and Technical Information of China (English)

    Chen Liu; Caihong Zhu; Jun Li; Pinghui Zhou; Min Chen; Huilin Yang; Bin Li

    2015-01-01

    Annulus fibrosus (AF) tissue engineering has recently received increasing attention as a treatment for intervertebral disc (IVD) degeneration;however, such engineering remains challenging because of the remarkable complexity of AF tissue. In order to engineer a functional AF replacement, the fabrication of cell-scaffold constructs that mimic the cellular, biochemical and structural features of native AF tissue is critical. In this study, we fabricated aligned fibrous polyurethane scaffolds using an electrospinning technique and used them for culturing AF-derived stem/progenitor cells (AFSCs). Random fibrous scaffolds, also prepared via electrospinning, were used as a control. We compared the morphology, proliferation, gene expression and matrix production of AFSCs on aligned scaffolds and random scaffolds. There was no apparent difference in the attachment or proliferation of cells cultured on aligned scaffolds and random scaffolds. However, compared to cells on random scaffolds, the AFSCs on aligned scaffolds were more elongated and better aligned, and they exhibited higher gene expression and matrix production of collagen-I and aggrecan. The gene expression and protein production of collagen-II did not appear to differ between the two groups. Together, these findings indicate that aligned fibrous scaffolds may provide a favourable microenvironment for the differentiation of AFSCs into cells similar to outer AF cells, which predominantly produce collagen-I matrix.

  14. Fibre-matrix interaction in the human annulus fibrosus.

    Science.gov (United States)

    Guo, Zaoyang; Shi, Xiaohao; Peng, Xiongqi; Caner, Ferhun

    2012-01-01

    Although the mechanical behaviour of the human annulus fibrosus has been extensively studied, the interaction between the collagen fibres and the ground matrix has not been well understood and is therefore ignored by most constitutive models. The objective of this study is to identify the significance of the fibre-matrix interaction in the human annulus fibrosus by careful investigation of the experimental data, the theoretical constitutive models, and the numerical simulation results in the literature. Based on the experimental results from biaxial and uniaxial tests, it is shown that the mechanical behaviour of the matrix can be well simulated by an incompressible neo-Hookean type model, but the effective stiffness of the matrix depends on fibre stretch ratio, which can only be explained by fibre-matrix interaction. Furthermore, we find that this interaction takes place anisotropically between the matrix and the fibres distributed in different proportions in different directions. The dependence of the tangent stiffness of the matrix on the first invariant of the deformation tensor can also be explained by this fibre orientation dispersion.

  15. Biaxial mechanics and inter-lamellar shearing of stem-cell seeded electrospun angle-ply laminates for annulus fibrosus tissue engineering.

    Science.gov (United States)

    Driscoll, Tristan P; Nakasone, Ryan H; Szczesny, Spencer E; Elliott, Dawn M; Mauck, Robert L

    2013-06-01

    The annulus fibrosus (AF) of the intervertebral disk plays a critical role in vertebral load transmission that is heavily dependent on the microscale structure and composition of the tissue. With degeneration, both structure and composition are compromised, resulting in a loss of AF mechanical function. Numerous tissue engineering strategies have addressed the issue of AF degeneration, but few have focused on recapitulation of AF microstructure and function. One approach that allows for generation of engineered AF with appropriate (+/-)30° lamellar microstructure is the use of aligned electrospun scaffolds seeded with mesenchymal stem cells (MSCs) and assembled into angle-ply laminates (APL). Previous work indicates that opposing lamellar orientation is necessary for development of near native uniaxial tensile properties. However, most native AF tensile loads are applied biaxially, as the disk is subjected to multi-axial loads and is constrained by its attachments to the vertebral bodies. Thus, the objective of this study was to evaluate the biaxial mechanical response of engineered AF bilayers, and to determine the importance of opposing lamellar structure under this loading regime. Opposing bilayers, which replicate native AF structure, showed a significantly higher modulus in both testing directions compared to parallel bilayers, and reached ∼60% of native AF biaxial properties. Associated with this increase in biaxial properties, significantly less shear, and significantly higher stretch in the fiber direction, was observed. These results provide additional insight into native tissue structure-function relationships, as well as new benchmarks for engineering functional AF tissue constructs.

  16. Quantifying the contributions of structure to annulus fibrosus mechanical function using a nonlinear, anisotropic, hyperelastic model.

    Science.gov (United States)

    Guerin, Heather Lynch; Elliott, Dawn M

    2007-04-01

    The annulus fibrosus of the intervertebral disc is comprised of concentric lamella of oriented collagen fibers embedded in a hydrated proteoglycan matrix with smaller amounts of minor collagens, elastin, and small proteoglycans. Its structure and composition enable the disc to withstand complex loads and result in inhomogeneous, anisotropic, and nonlinear mechanical behaviors. The specific contributions of the annulus fibrosus constituent structures to mechanical function remain unclear. Therefore, the objective of this study was to use a structurally motivated, anisotropic, nonlinear strain energy model of annulus fibrosus to determine the relative contributions of its structural components to tissue mechanical behavior. A nonlinear, orthotropic hyperelastic model was developed for the annulus fibrosus. Terms to describe fibers, matrix, and interactions between annulus fibrosus structures (shear and normal to the fiber directions) were explicitly included. The contributions of these structures were analyzed by including or removing terms and determining the effect on the fit to multidimensional experimental data. Correlation between experimental and model-predicted stress, a Bland-Altman analysis of bias and standard deviation of residuals, and the contribution of structural terms to overall tissue stress were calculated. Both shear and normal interaction terms were necessary to accurately model multidimensional behavior. Inclusion of shear interactions more accurately described annulus fibrosus nonlinearity. Fiber stretch and shear interactions dominated contributions to circumferential direction stress, while normal and shear interactions dominated axial stress. The results suggest that interactions between fibers and matrix, perhaps facilitated by crosslinks, elastin, or minor collagens, augment traditional (i.e., fiber-uncrimping) models of nonlinearity.

  17. An annulus fibrosus closure device based on a biodegradable shape-memory polymer network.

    Science.gov (United States)

    Sharifi, Shahriar; van Kooten, Theo G; Kranenburg, Hendrik-Jan C; Meij, Björn P; Behl, Marc; Lendlein, Andreas; Grijpma, Dirk W

    2013-11-01

    Injuries to the intervertebral disc caused by degeneration or trauma often lead to tearing of the annulus fibrosus (AF) and extrusion of the nucleus pulposus (NP). This can compress nerves and cause lower back pain. In this study, the characteristics of poly(D,L-lactide-co-trimethylene carbonate) networks with shape-memory properties have been evaluated in order to prepare biodegradable AF closure devices that can be implanted minimally invasively. Four different macromers with (D,L-lactide) to trimethylene carbonate (DLLA:TMC) molar ratios of 80:20, 70:30, 60:40 and 40:60 with terminal methacrylate groups and molecular weights of approximately 30 kg mol(-1) were used to prepare the networks by photo-crosslinking. The mechanical properties of the samples and their shape-memory properties were determined at temperatures of 0 °C and 40 °C by tensile tests- and cyclic, thermo-mechanical measurements. At 40 °C all networks showed rubber-like behavior and were flexible with elastic modulus values of 1.7-2.5 MPa, which is in the range of the modulus values of human annulus fibrosus tissue. The shape-memory characteristics of the networks were excellent with values of the shape-fixity and the shape-recovery ratio higher than 98 and 95%, respectively. The switching temperatures were between 10 and 39 °C. In vitro culture and qualitative immunocytochemistry of human annulus fibrosus cells on shape-memory films with DLLA:TMC molar ratios of 60:40 showed very good ability of the networks to support the adhesion and growth of human AF cells. When the polymer network films were coated by adsorption of fibronectin, cell attachment, cell spreading, and extracellular matrix production was further improved. Annulus fibrosus closure devices were prepared from these AF cell-compatible materials by photo-polymerizing the reactive precursors in a mold. Insertion of the multifunctional implant in the disc of a cadaveric canine spine showed that these shape-memory devices could be

  18. A Novel Method for Repeatable Failure Testing of Annulus Fibrosus.

    Science.gov (United States)

    Werbner, Benjamin; Zhou, Minhao; O'Connell, Grace

    2017-11-01

    Tears in the annulus fibrosus (AF) of the intervertebral disk can result in disk herniation and progressive degeneration. Understanding AF failure mechanics is important as research moves toward developing biological repair strategies for herniated disks. Unfortunately, failure mechanics of fiber-reinforced tissues, particularly tissues with fibers oriented off-axis from the applied load, is not well understood, partly due to the high variability in reported mechanical properties and a lack of standard techniques ensuring repeatable failure behavior. Therefore, the objective of this study was to investigate the effectiveness of midlength (ML) notch geometries in producing repeatable and consistent tissue failure within the gauge region of AF mechanical test specimens. Finite element models (FEMs) representing several notch geometries were created to predict the location of bulk tissue failure using a local strain-based criterion. FEM results were validated by experimentally testing a subset of the modeled specimen geometries. Mechanical testing data agreed with model predictions (∼90% agreement), validating the model's predictive power. Two of the modified dog-bone geometries ("half" and "quarter") effectively ensured tissue failure at the ML for specimens oriented along the circumferential-radial and circumferential-axial directions. The variance of measured mechanical properties was significantly lower for notched samples that failed at the ML, suggesting that ML notch geometries result in more consistent and reliable data. In addition, the approach developed in this study provides a framework for evaluating failure properties of other fiber-reinforced tissues, such as tendons and meniscus.

  19. Comparison of decellularization protocols for preparing a decellularized porcine annulus fibrosus scaffold.

    Directory of Open Access Journals (Sweden)

    Haiwei Xu

    Full Text Available Tissue-specific extracellular matrix plays an important role in promoting tissue regeneration and repair. We hypothesized that decellularized annular fibrosus matrix may be an appropriate scaffold for annular fibrosus tissue engineering. We aimed to determine the optimal decellularization method suitable for annular fibrosus. Annular fibrosus tissue was treated with 3 different protocols with Triton X-100, sodium dodecyl sulfate (SDS and trypsin. After the decellularization process, we examined cell removal and preservation of the matrix components, microstructure and mechanical function with the treatments to determine which method is more efficient. All 3 protocols achieved decellularization; however, SDS or trypsin disturbed the structure of the annular fibrosus. All protocols maintained collagen content, but glycosaminoglycan content was lost to different degrees, with the highest content with TritonX-100 treatment. Furthermore, SDS decreased the tensile mechanical property of annular fibrosus as compared with the other 2 protocols. MTT assay revealed that the decellularized annular fibrosus was not cytotoxic. Annular fibrosus cells seeded into the scaffold showed good viability. The Triton X-100-treated annular fibrosus retained major extracellular matrix components after thorough cell removal and preserved the concentric lamellar structure and tensile mechanical properties. As well, it possessed favorable biocompatibility, so it may be a suitable candidate as a scaffold for annular fibrosus tissue engineering.

  20. Mechanical restoration and failure analyses of a hydrogel and scaffold composite strategy for annulus fibrosus repair

    NARCIS (Netherlands)

    Long, Rose G.; Buerki, Alexander; Zysset, Philippe; Eglin, David; Grijpma, Dirk W.; Blanquer, Sebastien B. G.; Hecht, Andrew C.; Iatridis, James C.

    2016-01-01

    Unrepaired defects in the annulus fibrosus of intervertebral disks are associated with degeneration and persistent back pain. A clinical need exists for a disk repair strategy that can seal annular defects, be easily delivered during surgical procedures, and restore biomechanics with low risk of her

  1. A combined biomaterial and cellular approach for annulus fibrosus rupture repair

    NARCIS (Netherlands)

    Pirvu, Tatiana; Blanquer, Sebastien B. G.; Benneker, Lorin M.; Grijpma, Dirk W.; Richards, Robert G.; Alini, Mauro; Eglin, David; Grad, Sibylle; Li, Zhen

    2015-01-01

    Recurrent intervertebral disc (IVD) herniation and degenerative disc disease have been identified as the most important factors contributing to persistent pain and disability after surgical discectomy. An annulus fibrosus (AF) closure device that provides immediate closure of the AF rupture, restore

  2. An annulus fibrosus closure device based on a biodegradable shape-memory polymer network

    NARCIS (Netherlands)

    Sharifi, Shahriar; van Kooten, Theo G.; Kranenburg, Hendrik-Jan C.; Meij, Bjorn P.; Behl, Marc; Lendlein, Andreas; Grijpma, Dirk W.

    2013-01-01

    Injuries to the intervertebral disc caused by degeneration or trauma often lead to tearing of the annulus fibrosus (AF) and extrusion of the nucleus pulposus (NP). This can compress nerves and cause lower back pain. In this study, the characteristics of poly(D,L-lactide-co-trimethylene carbonate) ne

  3. Mechanics of oriented electrospun nanofibrous scaffolds for annulus fibrosus tissue engineering.

    Science.gov (United States)

    Nerurkar, Nandan L; Elliott, Dawn M; Mauck, Robert L

    2007-08-01

    Engineering a functional replacement for the annulus fibrosus (AF) of the intervertebral disc is contingent upon recapitulation of AF structure, composition, and mechanical properties. In this study, we propose a new paradigm for AF tissue engineering that focuses on the reconstitution of anatomic fiber architecture and uses constitutive modeling to evaluate construct function. A modified electrospinning technique was utilized to generate aligned nanofibrous polymer scaffolds for engineering the basic functional unit of the AF, a single lamella. Scaffolds were tested in uniaxial tension at multiple fiber orientations, demonstrating a nonlinear dependence of modulus on fiber angle that mimicked the nonlinearity and anisotropy of native AF. A homogenization model previously applied to native AF successfully described scaffold mechanical response, and parametric studies demonstrated that nonfibrillar matrix, along with fiber connectivity, are key contributors to tensile mechanics for engineered AF. We demonstrated that AF cells orient themselves along the aligned scaffolds and deposit matrix that contributes to construct mechanics under loading conditions relevant to the in vivo environment. The homogenization model was applied to cell-seeded constructs and provided quantitative measures for the evolution of matrix and interfibrillar interactions. Finally, the model demonstrated that at fiber angles of the AF (28 degrees -44 degrees ), engineered material behaved much like native tissue, suggesting that engineered constructs replicate the physiologic behavior of the single AF lamella. Constitutive modeling provides a powerful tool for analysis of engineered AF neo-tissue and native AF tissue alike, highlighting key mechanical design criteria for functional AF tissue engineering.

  4. Collagen fibrillogenesis in the development of the annulus fibrosus of the intervertebral disc.

    Science.gov (United States)

    Hayes, Anthony J; Isaacs, Marc D; Hughes, C; Caterson, B; Ralphs, J R

    2011-10-11

    The annulus fibrosus of the intervertebral disc is a complex, radial-ply connective tissue consisting of concentric lamellae of oriented collagen. Whilst much is known of the structure of the mature annulus, less is known of how its complex collagenous architecture becomes established; an understanding of which could inform future repair/regenerative strategies. Here, using a rat disc developmental series, we describe events in the establishment of the collagenous framework of the annulus at light and electron microscopic levels and examine the involvement of class I and II small leucine rich proteoglycans (SLRPs) in the matrix assembly process. We show that a period of sustained, ordered matrix deposition follows the initial cellular differentiation/orientation phase within the foetal disc. Fibrillar matrix is deposited from recesses within the plasma membrane into compartments of interstitial space within the outer annulus - the orientation of the secreted collagen reflecting the initial cellular orientation of the laminae. Medially, we demonstrate the development of a reinforcing 'cage' of collagen fibre bundles around the foetal nucleus pulpous. This derives from the fusion of collagen bundles between presumptive end-plate and inner annulus. By birth, the distinct collagenous architectures are established and the disc undergoes considerable enlargement to maturity. We show that fibromodulin plays a prominent role in foetal development of the annulus and its attachment to vertebral bodies. With the exception of keratocan, the other SLRPs appear associated more with cartilage development within the vertebral column, but all become more prominent within the disc during its growth and differentiation.

  5. Collagen fibrillogenesis in the development of the annulus fibrosus of the intervertebral disc

    Directory of Open Access Journals (Sweden)

    AJ Hayes

    2011-10-01

    Full Text Available The annulus fibrosus of the intervertebral disc is a complex, radial-ply connective tissue consisting of concentric lamellae of oriented collagen. Whilst much is known of the structure of the mature annulus, less is known of how its complex collagenous architecture becomes established; an understanding of which could inform future repair/regenerative strategies. Here, using a rat disc developmental series, we describe events in the establishment of the collagenous framework of the annulus at light and electron microscopic levels and examine the involvement of class I and II small leucine rich proteoglycans (SLRPs in the matrix assembly process. We show that a period of sustained, ordered matrix deposition follows the initial cellular differentiation/orientation phase within the foetal disc. Fibrillar matrix is deposited from recesses within the plasma membrane into compartments of interstitial space within the outer annulus – the orientation of the secreted collagen reflecting the initial cellular orientation of the laminae. Medially, we demonstrate the development of a reinforcing ‘cage’ of collagen fibre bundles around the foetal nucleus pulpous. This derives from the fusion of collagen bundles between presumptive end-plate and inner annulus. By birth, the distinct collagenous architectures are established and the disc undergoes considerable enlargement to maturity. We show that fibromodulin plays a prominent role in foetal development of the annulus and its attachment to vertebral bodies. With the exception of keratocan, the other SLRPs appear associated more with cartilage development within the vertebral column, but all become more prominent within the disc during its growth and differentiation.

  6. Fibrin-genipin annulus fibrosus sealant as a delivery system for anti-TNFα drug

    Science.gov (United States)

    Likhitpanichkul, Morakot; Kim, Yesul; Torre, Olivia M; See, Eugene; Kazezian, Zepur; Pandit, Abhay; Hecht, Andrew C

    2015-01-01

    Background context Intervertebral discs (IVD) are attractive targets for local drug delivery because they are avascular structures with limited transport. Painful IVDs are in a chronic inflammatory state. While anti-inflammatories show poor performance in clinical trials their efficacy treating IVD cells suggests that sustained, local drug delivery directly to painful IVDs may be beneficial. Purpose To determine if genipin crosslinked fibrin (FibGen) with collagen type I hollow spheres (CHS) can serve as a drug delivery carrier for the anti-TNFα drug, infliximab. Infliximab was chosen as a model drug because of the known role of TNFα in increasing downstream production of several pro-inflammatory cytokines and pain mediators. FibGen was used as drug carrier because it is adhesive injectable, slowly degrading hydrogel with potential to seal annulus fibrosus (AF) defects. CHS allow simple and non-damaging drug loading and could act as a drug reservoir to improve sustained delivery. Study Design/Setting Biomaterials and human AF cell culture study to determine drug release kinetics and efficacy. Methods Infliximab was delivered at low and high concentrations using FibGen with and without CHS. Gels were analyzed for structure, drug release kinetics, and efficacy treating human AF cells following release. This work was funded by grants from the NIAMS/NIH (R01 AR057397), AO Foundation, and from the Icahn School of Medicine at Mount Sinai. Results Fibrin showed rapid infliximab drug release but degraded quickly. CHS alone showed a sustained release profile but the small spheres may not remain in a degenerated IVD with fissures. FibGen showed steady and low levels of infliximab release that was increased when loaded with higher drug concentrations. Infliximab was bound in CHS when delivered within FibGen and was only released following enzymatic degradation. The infliximab released over 20 days retained its bioactivity as confirmed by the sustained reduction of IL-1

  7. Targeting the annulus fibrosus of the intervertebral disc: Col1a2-Cre(ER)T mice show specific activity of Cre recombinase in the outer annulus fibrosus.

    Science.gov (United States)

    Bedore, Jake; Quesnel, Katherine; Quinonez, Diana; Séguin, Cheryle A; Leask, Andrew

    2016-06-01

    Degeneration of the intervertebral disc (IVD) is a major underlying contributor to back pain-the single leading cause of disability worldwide. However, we possess a limited understanding of the etiology underlying IVD degeneration. To date, there are a limited number of mouse models that have been used to target proteins in specific compartments of the IVD to explore their functions in disc development, homeostasis and disease. Furthermore, the majority of reports exploring the composition and function of the outer encapsulating annulus fibrosus (AF) of the IVD have considered it as one tissue, without considering the numerous structural and functional differences existing between the inner and outer AF. In addition, no mouse models have yet been reported that enable specific targeting of genes within the outer AF. In the current report, we discuss these issues and demonstrate the localized activity of Cre recombinase in the IVD of Col1a2-Cre(ER)T;ROSA26mTmG mice possessing a tamoxifen-dependent Cre recombinase driven by a Cola2 promoter and distal enhancer and the mTmG fluorescent reporter. Following tamoxifen injection of 3-week-old Col1a2-Cre(ER)T;ROSA26mTmG mice, we show Cre activity specifically in the outer AF of the IVD, as indicated by expression of the GFP reporter. Thus, Col1a2-Cre(ER)T;ROSA26mTmG mice may prove to be a valuable tool in delineating the function of proteins in this unique compartment of the IVD, and in further exploring the compositional differences between the inner and outer AF in disc homeostasis, aging and disease.

  8. Effects of cyclic tensile strain on actin cytoskeleton rearrangement in annulus fibrosus cells%周期性牵张椎间盘纤维环细胞肌动蛋白骨架的重排

    Institute of Scientific and Technical Information of China (English)

    张德宏; 方鹏飞; 王兴盛; 赵继荣; 李晓娜

    2016-01-01

    BACKGROUND:When the intervertebral disc is under stress, the hydraulic pressure generated inside the nucleus pulposus makes the annulus fibrosus extend outward and expand, and the annulus colagen fibers are stretched so that the extracelular matrix of annulus fibrosus cels is also under the pressure. In the intervertebral disc, aggrecan is the main component of proteoglycans, matrix metaloproteinase-2 is a major enzyme for extracelular matrix degradation, and tissue inhibitor of metaloproteinase is a multifunctional specific inhibition factor for matrix metaloproteinase activity. There is a mutual regulation between the latter two to keep the homeostasis between them. OBJECTIVE: To investigate the mechanism of cyclic tensile strain in the metabolism of intervertebral disc annulus matrix. METHODS:Rat anulus fibrosus cels were subjected to 2% or 10% cyclic tensile strain at 1.0 Hz for 2 and 12 hours using Flexcel4000 tension system. Then cels were colected and cultured in conditioned medium for gene and protein detection. Real-time quantitative PCR was used to detect mRNA expression of aggrecan, matrix metaloproteinases-2 and tissue inhibitor of metaloproteinase-2. Gelatin zymography was used to detect matrix metaloproteinases-2 activity. RESULTS AND CONCLUSION:The use of 2% cyclic tensile strain had no obvious effect on the stress fiber of actin cytoskeleton, whereas actin cytoskeleton was depolymerized in response to 10% cyclic tensile strain. The 2% cyclic tensile strain raised the expression of Aggrecan at 12 hours; whereas raised the matrix metaloproteinases-2 and tissue inhibitor of metaloproteinase-2 at 2 hours, both of which were in homeostasis; matrix metaloproteinases-2 activity had no significant changes. 10% cyclic tensile strain had no effect on the mRNA expression of Aggrecan. No matter stretching 2 or 12 hours, the matrix metaloproteinases-2 was up-regulated, and the tissue inhibitor of metaloproteinase-2 was down-regulated, both of which were not in

  9. Biaxial testing of canine annulus fibrosus tissue under changing salt concentrations

    Directory of Open Access Journals (Sweden)

    Jacques M. Huyghe

    2010-03-01

    Full Text Available The in vivo mechanics of the annulus fibrosus of the intervertebral disc is one of biaxial rather than uniaxial loading. The material properties of the annulus are intimately linked to the osmolarity in the tissue. This paper presents biaxial relaxation experiments of canine annulus fibrosus tissue under stepwise changes of external salt concentration. The force tracings show that stresses are strongly dependent on time, salt concentration and orientation. The force tracing signature of are sponse to a change instrain, is one of a jumpin stress that relaxes partly as the new strain is maintained. The force tracing signature of a stepwise change in salt concentration is a progressive monotonous change in stress towards a new equilibrium value. Although the number of samples does not allow any definitive quantitative conclusions, the trends may shed light on the complex interaction among the directionality of forces, strains and fiber orientation on one hand, and on the other hand, the osmolarity of the tissue. The dual response to a change in strain is understood as an immediate response before fluid flows in or out of the tissue, followed by a progressive readjustment of the fluid content in time because of the gradient in fluid chemical potential between the tissue and the surrounding solution.A mecânica in vivo do anel fibroso do disco intervertebral é baseada em carregamento biaxial ao invés de uniaxial. As propriedades materiais do anel estão intimamente ligadas à osmolaridade no tecido. O artigo apresenta experimentos de relaxação biaxiais do anel fibroso de um tecido canino sob mudanças abruptas na concentração externa de sal. A assinatura da força devido à mudança brusca de salinidade resulta em uma progressiva e monótona mudança na tensão em direção a um novo valor de equilíbrio. Embora o número de amostras não permita nenhuma conclusão quantitativa, as tendências podem abrir uma luz no entendimento das intera

  10. Self-assembly of aligned tissue-engineered annulus fibrosus and intervertebral disc composite via collagen gel contraction.

    Science.gov (United States)

    Bowles, Robby D; Williams, Rebecca M; Zipfel, Warren R; Bonassar, Lawrence J

    2010-04-01

    Many cartilaginous tissues such as intervertebral disc (IVD) display a heterogeneous collagen microstructure that results in mechanical anisotropy. These structures are responsible for mechanical function of the tissue and regulate cellular interactions and metabolic responses of cells embedded within these tissues. Using collagen gels seeded with ovine annulus fibrosus cells, constructs of varying structure and heterogeneity were created to mimic the circumferential alignment of the IVD. Alignment was induced within gels by contracting annular gels around an inner boundary using both a polyethylene center and alginate center to create a composite engineered IVD. Collagen alignment and heterogeneity were measured using second harmonic generation microscopy. Decreasing initial collagen density from 2.5 mg/mL to 1 mg/mL produced greater contraction of constructs, resulting in gels that were 55% and 6.2% of the original area after culture, respectively. As a result, more alignment occurred in annular-shaped 1 mg/mL gels compared with 2.5 mg/mL gels (p < 0.05). This alignment was also produced in a composite-engineered IVD with alginate nucleus pulposus. The resulting collagen alignment could promote further aligned collagen development necessary for the creation of a mechanically functional tissue-engineered IVD.

  11. Protective effect of niacinamide on interleukin-1beta-induced annulus fibrosus type II collagen degeneration in vitro.

    Science.gov (United States)

    Duan, Deyu; Yang, Shuhua; Shao, Zengwu; Wang, Hong; Xiong, Xiaoqian

    2007-02-01

    The protective effect of niacinamide on interleukin-1beta (IL-1beta)-induced annulus fibrosus (AF) type II collagen degeneration in vitro and the mechanism were investigated. Chiba's intervertebral disc (IVD) culture models in rabbits were established and 48 IVDs from 12 adult Japanese white rabbits were randomly divided into 4 groups: normal control group, niacinamide-treated group, type II collagen degneration group (IL-1beta) and treatment group (niacinamide+IL-1beta). After culture for one week, AFs were collected for inducible nitric oxide synthase (iNOS), cysteine containing aspartate specific protease-3 (Caspase-3) and type II collagen immunohistochemical examination, and type II collagen reverse transcription polymerase chain reaction (RT-PCR). The results showed that rate of iNOS positive staining AF cells in the 4 groups was 17.6%, 10.9%, 73.9% and 19.3% respectively. The positive rate in treatment group was significantly lower than in the type II collagen degeneration group (Pniacinamide could effectively inhibit IL-1beta stimulated increase of iNOS and Caspase-3 in AF, and alleviate IL-1beta-caused destruction and synthesis inhibition of type II collagen. Niacinamide is of potential for clinical treatment of IVD degeneration.

  12. The transmembrane heparan sulphate proteoglycan syndecan-4 is involved in establishment of the lamellar structure of the annulus fibrosus of the intervertebral disc.

    Science.gov (United States)

    Beckett, M C; Ralphs, J R; Caterson, B; Hayes, A J

    2015-08-14

    The annulus fibrosus of the intervertebral disc unites adjacent vertebral bodies along the length of the spine and provides tensile resistance towards compressive, twisting and bending movements arising through gait. It consists of a nested series of oriented collagenous lamellae, arranged in cross-ply circumferentially around the nucleus pulposus. The organisation of oriented collagen in the annulus is established during foetal development by an identical arrangement of oriented fibroblasts that are precisely organised into cell sheets, or laminae. These provide a template for ordered deposition of extracellular matrix material on cell surfaces, by means of a poorly understood mechanism involving the actin cytoskeleton. In this study, we investigate the role of two cell surface heparan sulphate proteoglycans (HSPGs), glypican-6 and syndecan-4, in the matrix assembly process in the developmental rat intervertebral disc. We compare their expression patterns with those of heparan sulphate and the interactive, cell-surface adhesive glycoprotein, fibronectin, and relate these to the stage-specific collagenous architectures present within the annulus at both light and electron microscopic levels. We show that both proteoglycans are strongly associated with the development, growth and aging of the intervertebral disc. Furthermore, the immunohistochemical labelling patterns suggest that syndecan-4, in particular, plays a potentially-significant role in annulus formation. We propose that this HSPG mediates interaction between the actin cytoskeleton and nascent extracellular matrix in the lamellar organisation of annulus tissue. These data add considerably towards an understanding of how cells organise and maintain complex, oriented extracellular matrices and has particular clinical relevance to the fields of tissue engineering and repair.

  13. Protective Effect of Niacinamide on interleukin-1β-induced Annulus Fibrosus Type Ⅱ Collagen Degeneration in vitro

    Institute of Scientific and Technical Information of China (English)

    DUAN Deyu; YANG Shuhua; SHAO Zengwu; WANG Hong; XIONG Xiaoqian

    2007-01-01

    The protective effect of niacinamide on interleukin-1β (IL-1β)-induced annulus fibrosus (AF) type Ⅱ collagen degeneration in vitro and the mechanism were investigated. Chiba's intervertebrai disc (IVD) culture models in rabbits were established and 48 IVDs from 12 adult Japanese white rabbits were randomly divided into 4 groups: normal control group, niacinamide-treated group, type Ⅱ collagen degneration group (IL-1β) and treatment group (niacinamide+IL-1β). After culture for one week, AFs were collected for inducible nitric oxide synthase (iNOS), cysteine containing aspartate specific protease-3 (Caspase-3) and type Ⅱ collagen immunohistochemical examination, and type Ⅱ collagen reverse transcription polymerase chain reaction (RT-PCR). The results showed that rate of iNOS positive staining AF cells in the 4 groups was 17.6%, 10.9%, 73.9% and 19.3% respectively. The positive rate in treatment group was significantly lower than in the type Ⅱ collagen degeneration group (P<0.01). Rate of Caspase-3 positive staining AF cells in the 4 groups was 3.4%, 4.2%, 17.6% and 10.3% respectively. The positive rate in treatment group was lower than in the type Ⅱ collagen degeneration group (P<0.01). Type Ⅱ collagen staining demonstrated that lamellar structure and continuity of collagen in treatment group was better reversed than in the degeneration group. RT-PCR revealed that the expression of type Ⅱ collagen in treatment group was significantly stronger than that in type Ⅱ collagen degeneration group (P<0.01). It was concluded that niacinamide could effectively inhibit IL-1β stimulated increase of iNOS and Caspase-3 in AF, and alleviate IL-1β-caused destruction and synthesis inhibition of type Ⅱ collagen. Niacinamide is of potential for clinical treatment of IVD degeneration.

  14. Penetrating annulus fibrosus injuries affect dynamic compressive behaviors of the intervertebral disc via altered fluid flow: an analytical interpretation.

    Science.gov (United States)

    Michalek, Arthur J; Iatridis, James C

    2011-08-01

    Extensive experimental work on the effects of penetrating annular injuries indicated that large injuries impact axial compressive properties of small animal intervertebral discs, yet there is some disagreement regarding the sensitivity of mechanical tests to small injury sizes. In order to understand the mechanism of injury size sensitivity, this study proposed a simple one dimensional model coupling elastic deformations in the annulus with fluid flow into and out of the nucleus through both porous boundaries and through a penetrating annular injury. The model was evaluated numerically in dynamic compression with parameters obtained by fitting the solution to experimental stress-relaxation data. The model predicted low sensitivity of mechanical changes to injury diameter at both small and large sizes (as measured by low and high ratios of injury diameter to annulus thickness), with a narrow range of high sensitivity in between. The size at which axial mechanics were most sensitive to injury size (i.e., critical injury size) increased with loading frequency. This study provides a quantitative hypothetical model of how penetrating annulus fibrosus injuries in discs with a gelatinous nucleus pulposus may alter disc mechanics by changing nucleus pulposus fluid pressurization through introduction of a new fluid transport pathway though the annulus. This model also explains how puncture-induced biomechanical changes depend on both injury size and test protocol.

  15. Formation of lamellar cross bridges in the annulus fibrosus of the intervertebral disc is a consequence of vascular regression.

    Science.gov (United States)

    Smith, Lachlan J; Elliott, Dawn M

    2011-05-01

    Cross bridges are radial structures within the highly organized lamellar structure of the annulus fibrosus of the intervertebral disc that connect two or more non-consecutive lamellae. Their origin and function are unknown. During fetal development, blood vessels penetrate deep within the AF and recede during postnatal growth. We hypothesized that cross bridges are the pathways left by these receding blood vessels. Initially, the presence of cross bridges was confirmed in cadaveric human discs aged 25 and 53 years. Next, L1-L2 intervertebral discs (n=4) from sheep ranging in age from 75 days fetal gestation to adult were processed for paraffin histology. Mid-sagittal sections were immunostained for endothelial cell marker PECAM-1. The anterior and posterior AF were imaged using differential interference contrast microscopy, and the following parameters were quantified: total number of distinct lamellae, total number of cross bridges, percentage of cross bridges staining positive for PECAM-1, cross bridge penetration depth (% total lamellae), and PECAM-1 positive cross bridge penetration depth. Cross bridges were first observed at 100 days fetal gestation. The overall number peaked in neonates then remained relatively unchanged. The percentage of PECAM-1 positive cross bridges declined progressively from almost 100% at 100 days gestation to less than 10% in adults. Cross bridge penetration depth peaked in neonates then remained unchanged at subsequent ages. Depth of PECAM-1 positive cross bridges decreased progressively after birth. Findings were similar for both the anterior and posterior. The AF lamellar architecture is established early in development. It later becomes disrupted as a consequence of vascularization. Blood vessels then recede, perhaps due to increasing mechanical stresses in the surrounding matrix. In this study we present evidence that the pathways left by receding blood vessels remain as lamellar cross bridges. It is unclear whether the presence

  16. A comparison between porcine, ovine, and bovine intervertebral disc anatomy and single lamella annulus fibrosus tensile properties.

    Science.gov (United States)

    Monaco, Lauren A; DeWitte-Orr, Stephanie J; Gregory, Diane E

    2016-02-01

    This project aimed to compare gross anatomical measures and biomechanical properties of single lamellae from the annulus fibrosus of ovine and porcine lumbar vertebrae, and bovine tail vertebrae. The morphology of the vertebrae of these species differ significantly both from each other and from human, yet how these differences alter biomechanical properties is unknown. Geometric parameters measured in this study included: 1) absolute and relative intervertebral (IVD) and vertebral body height and 2) absolute and relative intervertebral disc (IVD) anterior-posterior (AP) and medial-lateral (ML) widths. Single lamella tensile properties included toe-region stress and stretch ratio, stiffness, and tensile strength. As expected, the bovine tail IVD revealed a more circular shape compared with both the ovine and porcine lumbar IVD. The bovine tail also had the largest IVD to vertebral body height ratio (due to having the highest absolute IVD height). Bovine tail lamellae were also found to be strongest and stiffest (in tension) while ovine lumbar lamellae were weakest and most compliant. Histological analysis revealed the greatest proportion of collagen in the bovine corroborating findings of increased strength and stiffness. The observed differences in anatomical shape, connective tissue composition, and tensile properties need to be considered when choosing an appropriate model for IVD research.

  17. Structure and mechanical function of the inter-lamellar matrix of the annulus fibrosus in the disc.

    Science.gov (United States)

    Tavakoli, Javad; Elliott, Dawn M; Costi, John J

    2016-08-01

    The inter-lamellar matrix (ILM) has an average thickness of less than 30 µm and lies between adjacent lamellae in the annulus fibrosus (AF). The microstructure and composition of the ILM have been studied in various anatomic regions of the disc; however, their contribution to AF mechanical properties and structural integrity is unknown. It was suggested that the ILM components, mainly elastic fibers and cross-bridges, play a role in providing mechanical integrity of the AF. Therefore, the manner in which they respond to different loadings and stabilize adjacent lamellae structure will influence AF tear formation and subsequent herniation. This review paper summarizes the composition, microstructure, and potential role of the ILM in the progression of disc herniation, clarifies the micromechanical properties of the ILM, and proposes critical areas for future studies. There are a number of unknown characteristics of the ILM, such as its mechanical role, impact on AF integrity, and ultrastructure of elastic fibers at the ILM-lamella boundary. Determining these characteristics will provide important information for tissue engineering, repair strategies, and the development of more-physiological computational models to study the initiation and propagation of AF tears that lead to herniation and degeneration. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1307-1315, 2016.

  18. 3D segmentation of annulus fibrosus and nucleus pulposus from T2-weighted magnetic resonance images

    Science.gov (United States)

    Castro-Mateos, Isaac; Pozo, Jose M.; Eltes, Peter E.; Del Rio, Luis; Lazary, Aron; Frangi, Alejandro F.

    2014-12-01

    Computational medicine aims at employing personalised computational models in diagnosis and treatment planning. The use of such models to help physicians in finding the best treatment for low back pain (LBP) is becoming popular. One of the challenges of creating such models is to derive patient-specific anatomical and tissue models of the lumbar intervertebral discs (IVDs), as a prior step. This article presents a segmentation scheme that obtains accurate results irrespective of the degree of IVD degeneration, including pathological discs with protrusion or herniation. The segmentation algorithm, employing a novel feature selector, iteratively deforms an initial shape, which is projected into a statistical shape model space at first and then, into a B-Spline space to improve accuracy. The method was tested on a MR dataset of 59 patients suffering from LBP. The images follow a standard T2-weighted protocol in coronal and sagittal acquisitions. These two image volumes were fused in order to overcome large inter-slice spacing. The agreement between expert-delineated structures, used here as gold-standard, and our automatic segmentation was evaluated using Dice Similarity Index and surface-to-surface distances, obtaining a mean error of 0.68 mm in the annulus segmentation and 1.88 mm in the nucleus, which are the best results with respect to the image resolution in the current literature.

  19. Fibrin-genipin adhesive hydrogel for annulus fibrosus repair: performance evaluation with large animal organ culture, in situ biomechanics, and in vivo degradation tests

    Directory of Open Access Journals (Sweden)

    M Likhitpanichkul

    2014-07-01

    Full Text Available Annulus fibrosus (AF defects from annular tears, herniation, and discectomy procedures are associated with painful conditions and accelerated intervertebral disc (IVD degeneration. Currently, no effective treatments exist to repair AF damage, restore IVD biomechanics and promote tissue regeneration. An injectable fibrin-genipin adhesive hydrogel (Fib-Gen was evaluated for its performance repairing large AF defects in a bovine caudal IVD model using ex vivo organ culture and biomechanical testing of motion segments, and for its in vivo longevity and biocompatibility in a rat model by subcutaneous implantation. Fib-Gen sealed AF defects, prevented IVD height loss, and remained well-integrated with native AF tissue following approximately 14,000 cycles of compression in 6-day organ culture experiments. Fib-Gen repair also retained high viability of native AF cells near the repair site, reduced nitric oxide released to the media, and showed evidence of AF cell migration into the gel. Biomechanically, Fib-Gen fully restored compressive stiffness to intact levels validating organ culture findings. However, only partial restoration of tensile and torsional stiffness was obtained, suggesting opportunities to enhance this formulation. Subcutaneous implantation results, when compared with the literature, suggested Fib-Gen exhibited similar biocompatibility behaviour to fibrin alone but degraded much more slowly. We conclude that injectable Fib-Gen successfully sealed large AF defects, promoted functional restoration with improved motion segment biomechanics, and served as a biocompatible adhesive biomaterial that had greatly enhanced in vivo longevity compared to fibrin. Fib-Gen offers promise for AF repairs that may prevent painful conditions and accelerated degeneration of the IVD, and warrants further material development and evaluation.

  20. The dura gide to annulus fibrosus closurement%人工生物膜修复椎间盘纤维环的研究

    Institute of Scientific and Technical Information of China (English)

    丁文元; 申勇; 郭金库; 贺延雷; 吴海龙; 曹来震; 李鹏飞

    2010-01-01

    Objective To evaluate the repair efficiency of dura gide to intervertebral disc annulus fibrosus defect. Methods Totallly 24 lumbar intervertebral discs of 8 sheep underwent one of the following 3 methods: (1) the disc annulus fibrosus was exposed through retroperitoneal approach without any farther procedure; (2) the disc annulus fibrosus was exposed and a defect was made, and then the defect was repaired with dura gide; (3) the disc annulus fibrosus was exposed and a defect was made as control. At the 12th week after surgery, 15 discs of 5 sheep underwent pressure-volume testing to assess the competency of the annulus fibrosus. MRI images and decalcified histology were performed on the remaining 9 discs of 3sheep. Results At the 12th week, the mean max-pressure in expose-only, excise-only and dura gide-reparied group was (4. 92 ±0. 17), (2. 48 ±0.39) and (3.76 ± 1.56) MPa, respectively. Both the competency in excised-only and dura gide-repaired groups was lower than in exposed-only group. The competency in dura gide-repaired groups was higher than in excise-only group ( P < 0. 05 ). MRI images and histology indicated that dura gide-repaired specimens were integrated well with the disc annulus fibrosus collagen.Conclusion There was a repair efficiency of dura gide to intervertebral disc annulus fibrosus defect. The mean competency recovery rate was 76.4%.%目的 用不同方法处理椎间盘纤维环,观察人工生物膜对椎间盘纤维环缺损的修复作用.方法 成年山羊8只,雌雄各4只,对每只羊的腰椎(腰2/3、腰3/4、腰4/5)椎间盘纤维环进行随机处理,处理方法包括:(1)暴露出椎间盘纤维环,不作任何处理;(2)暴露出椎间盘纤维环后,将其切开,用人下生物膜填充缺口;(3)暴露出椎间盘纤维环,尖刀将其切开,作为对照组.12周后,通过生物力学测试、核磁共振(MRI)及脱钙病理切片染色观察椎间盘纤维环的修复效果.结果 12周后,测试纤维环承受最

  1. Effects of loading frequency on matrix synthesis of annulus fibrosus cells in an intervertebral disc perfusion culture system%椎间盘灌注培养条件下压应力频率对纤维环细胞基质合成的影响

    Institute of Scientific and Technical Information of China (English)

    李培; 甘翼搏; 徐源; 李松涛; 宋磊; 周强

    2015-01-01

    目的:观察压应力频率对椎间盘纤维环(AF)细胞基质合成的影响.方法:获取4~6月龄巴马香猪胸腰段椎间盘72个后,随机分为无应力对照组和应力组(分别为0.1Hz组、0.5Hz组、1Hz组、3Hz组、5Hz组),每组12个样本,将各组椎间盘置于生物反应器中进行灌注培养.无应力对照组不施加应力刺激,各应力组每天施加对应频率的应力刺激2h.灌注培养5d后分离全层纤维环组织行HE染色、阿利新蓝染色、胞外基质基因Ag鄄grecan、Collagen Ⅰ、Collagen Ⅱ定量PCR、糖胺多糖(GAG)含量和羟脯氨酸(HYP)含量的检测.结果:培养5d后,各组纤维环组织仍保持天然的层状叠加结构.与对照组比较时,除5Hz组外其他应力组(0.1Hz、0.5Hz、1Hz、3Hz)纤维环组织阿利新蓝染色强度增强、各胞外基质基因的表达得到维持(0.1Hz)或上调(0.5Hz、1Hz、3Hz)、GAG和HYP的含量也维持在同等水平(0.1Hz)或显著升高(0.5Hz、1Hz、3Hz).然而各应力组组间比较时,5Hz组纤维环组织阿利新蓝染色强度、胞外基质基因的表达水平及GAG 和HYP 的含量比其他应力组(0.1Hz、0.5Hz、1Hz、3Hz)都下调(P<0.05).结论:椎间盘体外灌注培养条件下,压应力刺激频率影响纤维环细胞的基质合成,低频率(0.1~3Hz)的应力刺激增加基质合成,高频率(5Hz)的应力刺激减少基质合成.%Objectives: To investigate the effects of loading frequency on matrix synthesis of annulus fibrosus (AF) cells.Methods: Discs from porcine (4-6 months old) were isolated and randomly divided into control group (no loading) and loading groups(0.1Hz,0.5Hz,1Hz,3Hz and 5Hz group,respectively).All discs were put in tissue culture chamber for perfusion culturing.No loading was applied to the discs in the control group while different loading frequencies(0.1Hz,0.5Hz,1 Hz,3Hz and 5Hz,respectively) were applied to the discs in the loading groups.After culturing for 5 days,the full-thickness AF tissues were

  2. Penetrating Annulus Fibrosus Injuries Affect Dynamic Compressive Behaviors of the Intervertebral Disc Via Altered Fluid Flow: An Analytical Interpretation

    OpenAIRE

    Michalek, Arthur J.; Iatridis, James C.

    2011-01-01

    Extensive experimental work on the effects of penetrating annular injuries indicated that large injuries impact axial compressive properties of small animal intervertebral discs, yet there is some disagreement regarding the sensitivity of mechanical tests to small injury sizes. In order to understand the mechanism of injury size sensitivity, this study proposed a simple one dimensional model coupling elastic deformations in the annulus with fluid flow into and out of the nucleus through both ...

  3. Annulus Fibrosus Can Strip Hyaline Cartilage End Plate from Subchondral Bone: A Study of the Intervertebral Disk in Tension.

    Science.gov (United States)

    Balkovec, Christian; Adams, Michael A; Dolan, Patricia; McGill, Stuart M

    2015-10-01

    Study Design Biomechanical study on cadaveric spines. Objective Spinal bending causes the annulus to pull vertically (axially) on the end plate, but failure mechanisms in response to this type of loading are poorly understood. Therefore, the objective of this study was to identify the weak point of the intervertebral disk in tension. Methods Cadaveric motion segments (aged 79 to 88 years) were dissected to create midsagittal blocks of tissue, with ∼10 mm of bone superior and inferior to the disk. From these blocks, 14 bone-disk-bone slices (average 4.8 mm thick) were cut in the frontal plane. Each slice was gripped by its bony ends and stretched to failure at 1 mm/s. Mode of failure was recorded using a digital camera. Results Of the 14 slices, 10 failed by the hyaline cartilage being peeled off the subchondral bone, with the failure starting opposite the lateral annulus and proceeding medially. Two slices failed by rupturing of the trabecular bone, and a further two failed in the annulus. Conclusions The hyaline cartilage-bone junction is the disk's weak link in tension. These findings provide a plausible mechanism for the appearance of bone and cartilage fragments in herniated material. Stripping cartilage from the bony end plate would result in the herniated mass containing relatively stiff cartilage that does not easily resorb.

  4. FABRICATION AND ANALYSIS OF A NOVEL TISSUE ENGINEERED COMPOSITE BIPHASIC SCAFFOLD FOR ANNULUS FIBROSUS AND NUCLEUS PULPOSUS%新型一体化纤维环-髓核双相支架的制备与评估

    Institute of Scientific and Technical Information of China (English)

    许海委; 徐宝山; 杨强; 李秀兰; 马信龙; 夏群; 张春秋; 伍耀宏

    2013-01-01

    Objective To fabricate a novel composite scaffold with acellular demineralized bone matrix/acellular nucleus pulposus matrix and to verify the feasibility of using it as a scaffold for intervertebral disc tissue engineering through detecting physical and chemical properties. Methods Pig proximal femoral cancellous bone rings (10 mm in external diameter, 5 mm in internal diameter, and 3 mm in thickness) were fabricated, and were dealed with degreasing, decalcification, and decellularization to prepare the annulus fibrosus phase of scaffold. Nucleus pulposus was taken from pig tails, decellularized with Triton X-100 and deoxycholic acid, crushed and centrifugalized to prepare nucleus pulposus extracellular mtrtix which was injected into the center of annulus fibrosus phase. Then the composite scaffold was freeze-dryed, cross-linked with ultraviolet radiation/carbodiimide and disinfected for use. The scaffold was investigated by general observation, HE staining, and scanning electron microscopy, as well as porosity measurement, water absorption rate, and compressive elastic modulus. Adipose-derived stem cells (ADSCs) were cultured with different concentrations of scaffold extract (25%, 50%, and 100%) to assess cytotoxicity of the scaffold. The cell viability of ADSCs seeded on the scaffold was detected by Live/Dead staining. Results The scaffold was white by general observation. The HE staining revealed that there was no cell fragments on the scaffold, and the dye homogeneously distributed. The scanning electron microscopy showed that the pore of the annulus fibrosus phase interconnected and the pore size was uniform; acellular nucleus pulposus matrix microfilament interconnected forming a uniform network structure, and the junction of the scaffold was closely connected. The novel porous scaffold had a good pore interconnectivity with (343.00 ± 88.25) urn pore diameter of the annulus fibrosus phase, 82.98% ± 7.02% porosity and 621.53% ± 53.31% water absorption rate

  5. 组织工程椎间盘纤维环:如何更接近于天然%How to build a tissue-engineered intervertebral disc annulus fibrosus that is more close to the natural one?

    Institute of Scientific and Technical Information of China (English)

    袁德超; 陈竹; 冯大雄; 冯刚

    2015-01-01

    BACKGROUND:Tissue-engineered intervertebral disc has provided a new biological therapeutic approach for intervertebral disc degeneration. Tissue-engineered annulus fibrosus is one key step of constructing a complete tissue-engineered intervertebral disc. OBJECTIVE:To sum up the research progress of tissue-engineered annulus fibrosus from the folowing aspects: structural features, scaffold materials, seed cels. METHODS:PubMed database and Wanfang database (2000-2015) were retrieved by the key words of “tissue engineering, intervertebral disc, annulus fibrosus, seed cel, scaffold, construction” in Chinese and in English, respectively. According to inclusion and exclusion criteria, 48 literatures were involved for summarization. RESULTS AND CONCLUSION: Previous studies about tissue-engineered annulus fibrosus only focused on cel adhesion, proliferation and extracelular matrix secretion on the scaffold. Currently, tissue-engineered annulus fibrosus exhibit similar features to the natural annulus fibrosus in the folowing aspects: cel function, tissue structure and mechanical features, and relevant animal experiments have achieved certain results in animal experiments. However, it is stil difficult to build a tissue-engineered annulus fibrosus entirely similar to the natural one, and we need to further improve scaffold materials, culture conditions, colection of seed cels. The current strategies of annulus fibrosus construction stil focus on single phase of scaffold, and the biphasic scaffold and complete intervertebral disc scaffold wil be the trend of the researches. Technology of induced differentiation of stem cels provides a broach source of seed cels for tissue-engineered annulus fibrosus.%背景:组织工程椎间盘为椎间盘退行性变疾病的生物治疗提供了新的方法,组织工程纤维环是构建组织工程椎间盘的关键之一。目的:从纤维环结构特点、材料支架、种子细胞3方面,归纳总结组织工程纤维环

  6. 羊纤维环部分缺损动物模型的构建%Establishment of annulus fibrosus partial defect model in sheep

    Institute of Scientific and Technical Information of China (English)

    袁秋明; 马信龙; 徐宝山; 杨强; 刘越; 姜洪丰; 张杨; 杜立龙; 祁霁舟; 赵家宁

    2016-01-01

    目的:建立可用于椎间盘缺损修复研究的纤维环部分缺损动物模型。方法使用image J 1.46r软件测量5根羊脊柱X线片T12/L1~L6/S1椎间隙高度,轴向剖开T12/L1~L6/S1椎间盘,测量拟作缺损处纤维环厚度,使用11号尖刀在3根离体羊脊柱T12/L1~L5/6椎间盘左前方制作上底3 mm、下底5 mm、高5 mm、厚3 mm,下底朝向髓核的梯形缺损,上述羊脊柱均取自1岁龄绵羊。采用微创外侧手术入路在2只1岁龄绵羊T12/L1~L5/6椎间盘左前方制作相同规格的梯形缺损。通过轴向剖开椎间盘测量梯形缺损的边长、对切取的纤维环和少量髓核称质量,以此评估所制作的椎间盘梯形缺损。结果绵羊腰椎间隙高度为(4.45±0.28)mm,拟作缺损处纤维环厚度为(4.08±0.50) mm,分别与拟作梯形缺损的厚度(3 mm)和高度(5 mm)差异有统计学意义(P0.05);从离体和在体的羊腰椎间盘梯形缺损处取出的纤维环及髓核质量分别为(0.162±0.011)g和(0.166±0.014)g,两者差异无统计学意义(P>0.05)。结论通过微创外侧手术入路,使用实验中制作梯形缺损的方法可以简单、安全、可靠地制作出符合要求、能用于椎间盘缺损修复研究的羊纤维环部分缺损的动物模型。%Objective To establish an animal model of annulus fibrosus (AF) partial defect for the repairing of interver⁃tebral disc (IVD) defect. Methods Image J 1.46r software was used to measure the T12/L1-L6/S1 intervertebral height in ovine lumbar spine X-ray films. AF thickness was measured by axial split disc. A 11 blade was used to make a trapezoid de⁃fect of upper bottom 3 mm, lower bottom 5 mm, height 5 mm and thickness 3 mm, whose lower bottom toward the nucleus pulposus (NP) in the left front of ovine lumbar IVD in vitro. The minimally invasive lateral approach was used to make the same type of trapezoid defect in the left front of the ovine lumbar IVD in

  7. Study of building an integrated annulus fibrosus-nucleus pulposus biphasic scaffold based on bone matrix gelatin and cartilage matrix%以骨基质明胶及软骨基质构建一体化纤维环-髓核双相支架的实验研究

    Institute of Scientific and Technical Information of China (English)

    伍耀宏; 徐宝山; 杨强; 马信龙; 夏群; 李秀兰; 胡永成; 张杨; 张春秋

    2013-01-01

    Objective To fabricate an integrated annulus fibrosus-nucleus pulposus biphasic scaffolds based on bone matrix gelatin and acellular cartilage matrix,and to detect its property and cell compatibility.Methods An integrated annulus fibrosus-nucleus pulposus biphasic scaffold was fabricated by the following steps: preparing the hollow bone matrix gelatin ring,injecting the acellular cartilage homogenate into the center of the bone matrix gelatin ring,and freeze drying.Sample slices were stained with Hoechst 33258,picrosirius and HE.The internal structure of the scaffold was observed under a scanning electron microscope.The porosity and water absorption of the scaffold were also evaluated.Compressive mechanical property under wet situation was tested.The annulus fibrosus and nucleus pulposus cells were isolated from sheep disc and separately implanted into the corresponding sites of the scaffold,and biocompatibility of the scaffold was evaluated by scanning electron microscope and live/dead cell staining.Results Hoechst 33258 staining showed no residual cells,picrosirius staining was positive,and HE staining showed two parts linked closely.Under scanning electron microscope,the scaffold had porous structure,and the average pore size was 401.4±13.1 μm for annulus fibrosus,and 112.4±21.8 μm for nucleus pulposus.The porosity and water absorption of the scaffold was 73.37%±2.56% and 655.7%±78.6%,respectively.The average compressive elastic modulus of the scaffold (49.06 ±15.57) kpa was smaller than that of the native disc (135.9±28.9) kPa.Scanning electron microscope showed cells adhered on the scaffold surface,with secreted matrix around them,and live/dead cells staining showed cells with good activity on scaffolds.Conclusion The integrated annulus fibrosus-nucleus pulposus scaffold based on bone matrix gelatin and cartilage matrix is an ideal artificial disc material,in view of well pore size,closely linked boundary,and good biocompatibility.%目的 以

  8. Histological observation of a gelatin sponge transplant loaded with bone marrow-derived mesenchymal stem cells combined with platelet-rich plasma in repairing an annulus defect

    Science.gov (United States)

    Xu, Xiang; Hu, Jianzhong; Lu, Hongbin

    2017-01-01

    Objective To research the histological characteristics of a gelatin sponge transplant loaded with goat BMSCs (bone marrow-derived mesenchymal stem cells) combined with PRP (platelet-rich plasma) in repairing an annulus defect. Method BMSCs were separated from the iliac crest of goats, sub-cultured and identified after the third generation. Then, PRP was obtained using blood from the jugular vein of goats via two degrees of centrifugation. In the animal experiments, the goats were divided into the following three groups: a sham group, an injury group and a therapeutic group. In the sham group, we decompressed the lamina and exposed the annulus fibrosus. In the injury group, we exposed the annulus fibrosus after decompression of the lamina and created a 1 × 1 cm defect in the annulus using surgical instruments. In the therapeutic group, after decompression of the lamina, we exposed the annulus, created a 1 × 1 cm defect using surgical instruments, and placed a gelatin sponge combined with BMSCs and PRP into the defect for a combined method of repair. Three, six and twelve weeks after the surgery, the previously damaged or undamaged annulus tissue was removed from the three groups. Then, the above tissue was assayed using HE (hematoxylin-eosin) staining, Masson trichrome staining, AB-PAS (Alcian blue-periodic acid Schiff) staining, and type II collagen staining and observed by microscopy. Results From the HE staining, we observed that the number of repair cells gradually increased. Compared to the injury group, the cell density and gross morphology of cells in the therapeutic group were closer to those of the sham group. As observed by Masson trichrome gelatin staining, many of the fibroblast cells or tissues were under repair, and as time progressed, the number of fibroblast cells and amount of tissue gradually increased. The results of the AB-PAS staining suggest that chondrocytes participated in the repair of the annulus. The level of type II collagen gradually

  9. 来源于长管状骨的组织工程纤维环支架的理化特性及细胞生物学相容性研究%Study of physicochemical characteristics and biocompatibility of a novel tissue engineering annulus fibrosus scaffold derived from long bone

    Institute of Scientific and Technical Information of China (English)

    伍耀宏; 徐宝山; 杨强; 李秀兰; 张杨; 马信龙; 夏群; 闫中胜; 许海委

    2013-01-01

    , immunofluorescence staining of collagen type Ⅰ, Sirius red staining, SEM observation, pore diameter measurement, biomechanics test. The toxicity of leaching liquor from scaffolds was assessed by MTT assay, annulus fibrosus (AF) cells were isolated from goat and pass down to P1, and AF cells were seeded onto scaffolds with a syringe, cell - scaffold hybrids were assessed by LIVE / DEAD staining, scanning electron microscope ( SEM) and HE staining after 48 h cultrue in vitro. [ Results] The scaffold showed smooth and white surface under the gross observation, no residual cells were observed by Hoechst 33258 and HE staining, sirius red staining showed deep red staining scaffold. Immunofluorescence staining positive for collagen type Ⅰ, pores evenly distributed and connected in scaffolds with a average pore size of (401. 4 ± 13. 1) μm under the SEM, and the average compressive elastic modulus of integrated scaffold was 47. 75±6. 32kPa. MTT assay demonstrated no significant difference among the groups ( P > 0. 05) , LIVE/DEAD cells staining showed cells with good activity, SEM and HE staining showed cell adhesion on the stent scaffold surface and filamentous secretion surrounded cells. [ Conclusion ] The hollow ring scaffold decellularized thoroughly, has good pore structure and non -toxicity and good biocompatibility, shares similar mechanical property and composition with annulus fibrosus, therefore, it is a suitable candidate as an alternative cell - carrier for annulus fibrosus tissue engineering.

  10. Genipin-crosslinked fibrin hydrogels as a potential adhesive to augment intervertebral disc annulus repair.

    Science.gov (United States)

    Schek, R M; Michalek, A J; Iatridis, J C

    2011-04-18

    Treatment of damaged intervertebral discs is a significant clinical problem and, despite advances in the repair and replacement of the nucleus pulposus, there are few effective strategies to restore defects in the annulus fibrosus. An annular repair material should meet three specifications: have a modulus similar to the native annulus tissue, support the growth of disc cells, and maintain adhesion to tissue under physiological strain levels. We hypothesized that a genipin crosslinked fibrin gel could meet these requirements. Our mechanical results showed that genipin crosslinked fibrin gels could be created with a modulus in the range of native annular tissue. We also demonstrated that this material is compatible with the in vitro growth of human disc cells, when genipin:fibrin ratios were 0.25:1 or less, although cell proliferation was slower and cell morphology more rounded than for fibrin alone. Finally, lap tests were performed to evaluate adhesion between fibrin gels and pieces of annular tissue. Specimens created without genipin had poor handling properties and readily delaminated, while genipin crosslinked fibrin gels remained adhered to the tissue pieces at strains exceeding physiological levels and failed at 15-30%. This study demonstrated that genipin crosslinked fibrin gels show promise as a gap-filling adhesive biomaterial with tunable material properties, yet the slow cell proliferation suggests this biomaterial may be best suited as a sealant for small annulus fibrosus defects or as an adhesive to augment large annulus repairs. Future studies will evaluate degradation rate, fatigue behaviors, and long-term biocompatibility.

  11. Knockdown of asporin affects transforming growth factor-β1-induced matrix synthesis in human intervertebral annulus cells

    Directory of Open Access Journals (Sweden)

    Xu Jiang

    2016-10-01

    Conclusion: Our results have verified a functional feedback loop between TGF-β1 and asporin in human intervertebral annulus cells indicating that TGF-β1-induced annulus matrix biosynthesis can be significantly upregulated by knockdown of asporin. Therefore, asporin could be a potential new therapeutic target and inhibition of asporin could be adopted to enhance the anabolic effect of TGF-β1 in human intervertebral annulus cells in degenerative IVD diseases.

  12. Exogenous thymosin beta4 prevents apoptosis in human intervertebral annulus cells in vitro.

    Science.gov (United States)

    Tapp, H; Deepe, R; Ingram, J A; Yarmola, E G; Bubb, M R; Hanley, E N; Gruber, H E

    2009-12-01

    Loss of cells in the human disc due to programmed cell death (apoptosis) is a major factor in the aging and degenerating human intervertebral disc. Our objective here was to determine if thymosin beta(4) (TB4), a small, multifunctional 5 kDa protein with diverse activities, might block apoptosis in human annulus cells cultured in monolayer or three-dimensional (3D) culture. Apoptosis was induced in vitro using hydrogen peroxide or serum starvation. Annulus cells were processed for identification of apoptotic cells using the TUNEL method. The percentage of apoptotic cells was determined by cell counts. Annulus cells also were treated with TB4 for determination of proliferation, and proteoglycan production was assessed using cell titer and 1,2 dimethylmethylamine (DMB) assays and histological staining. A significant reduction in disc cell apoptosis occurred after TB4 treatment. The percentage of cells undergoing apoptosis decreased significantly in TB4 treated cells in both apoptosis induction designs. TB4 exposure did not alter proteoglycan production as assessed by either DMB measurement or histological staining. Our results indicate the need for further studies of the anti-apoptotic effect of TB4 and suggest that TB4 may have therapeutic application in future biological therapies for disc degeneration.

  13. Genipin-crosslinked fibrin hydrogels as a potential adhesive to augment intervertebral disc annulus repair

    Directory of Open Access Journals (Sweden)

    RM Schek

    2011-04-01

    Full Text Available Treatment of damaged intervertebral discs is a significant clinical problem and, despite advances in the repair and replacement of the nucleus pulposus, there are few effective strategies to restore defects in the annulus fibrosus. An annular repair material should meet three specifications: have a modulus similar to the native annulus tissue, support the growth of disc cells, and maintain adhesion to tissue under physiological strain levels. We hypothesized that a genipin crosslinked fibrin gel could meet these requirements. Our mechanical results showed that genipin crosslinked fibrin gels could be created with a modulus in the range of native annular tissue. We also demonstrated that this material is compatible with the in vitro growth of human disc cells, when genipin:fibrin ratios were 0.25:1 or less, although cell proliferation was slower and cell morphology more rounded than for fibrin alone. Finally, lap tests were performed to evaluate adhesion between fibrin gels and pieces of annular tissue. Specimens created without genipin had poor handling properties and readily delaminated, while genipin crosslinked fibrin gels remained adhered to the tissue pieces at strains exceeding physiological levels and failed at 15-30%. This study demonstrated that genipin crosslinked fibrin gels show promise as a gap-filling adhesive biomaterial with tunable material properties, yet the slow cell proliferation suggests this biomaterial may be best suited as a sealant for small annulus fibrosus defects or as an adhesive to augment large annulus repairs. Future studies will evaluate degradation rate, fatigue behaviors, and long-term biocompatibility.

  14. Enhancing cell migration in shape-memory alginate-collagen composite scaffolds: In vitro and ex vivo assessment for intervertebral disc repair.

    Science.gov (United States)

    Guillaume, Olivier; Naqvi, Syeda Masooma; Lennon, Kerri; Buckley, Conor Timothy

    2015-04-01

    Lower lumbar disc disorders pose a significant problem in an aging society with substantial socioeconomic consequences. Both inner tissue (nucleus pulposus) and outer tissue (annulus fibrosus) of the intervertebral disc are affected by such debilitating disorders and can lead to disc herniation and lower back pain. In this study, we developed an alginate-collagen composite porous scaffold with shape-memory properties to fill defects occurring in annulus fibrosus tissue of degenerated intervertebral discs, which has the potential to be administered using minimal invasive surgery. In the first part of this work, we assessed how collagen incorporation on preformed alginate scaffolds influences the physical properties of the final composite scaffold. We also evaluated the ability of annulus fibrosus cells to attach, migrate, and proliferate on the composite alginate-collagen scaffolds compared to control scaffolds (alginate only). In vitro experiments, performed in intervertebral disc-like microenvironmental conditions (low glucose and low oxygen concentrations), revealed that for alginate only scaffolds, annulus fibrosus cells agglomerated in clusters with limited infiltration and migration capacity. In comparison, for alginate-collagen scaffolds, annulus fibrosus cells readily attached and colonized constructs, while preserving their typical fibroblastic-like cell morphology with spreading behavior and intense cytoskeleton expression. In a second part of this study, we investigated the effects of alginate-collagen scaffold when seeded with bone marrow derived mesenchymal stem cells. In vitro, we observed that alginate-collagen porous scaffolds supported cell proliferation and extracellular matrix deposition (collagen type I), with secretion amplified by the local release of transforming growth factor-β3. In addition, when cultured in ex vivo organ defect model, alginate-collagen scaffolds maintained viability of transplanted mesenchymal stem cells for up to 5

  15. CHALLENGES AND STRATEGIES IN THE REPAIR OF RUPTURED ANNULUS FIBROSUS

    NARCIS (Netherlands)

    Guterl, Clare C.; See, Eugene Y.; Blanquer, Sebastien B. G.; Pandit, Abhay; Ferguson, Stephen J.; Benneker, Lorin M.; Grijpma, Dirk W.; Sakai, Daisuke; Eglin, David; Alini, Mauro; Iatridis, James C.; Grad, Sibylle

    2013-01-01

    Lumbar discectomy is the surgical procedure most frequently performed for patients suffering from low back pain and sciatica. Disc herniation as a consequence of degenerative or traumatic processes is commonly encountered as the underlying cause for the painful condition. While discectomy provides f

  16. CHALLENGES AND STRATEGIES IN THE REPAIR OF RUPTURED ANNULUS FIBROSUS

    NARCIS (Netherlands)

    Guterl, Clare C.; See, Eugene Y.; Blanquer, Sebastien B. G.; Pandit, Abhay; Ferguson, Stephen J.; Benneker, Lorin M.; Grijpma, Dirk W.; Sakai, Daisuke; Eglin, David; Alini, Mauro; Iatridis, James C.; Grad, Sibylle

    2013-01-01

    Lumbar discectomy is the surgical procedure most frequently performed for patients suffering from low back pain and sciatica. Disc herniation as a consequence of degenerative or traumatic processes is commonly encountered as the underlying cause for the painful condition. While discectomy provides

  17. Changes with Age and the Effect of Recombinant Human BMP-2 on Proteoglycan and Collagen Gene Expression in Rabbit Anulus Fibrosus Cells

    Institute of Scientific and Technical Information of China (English)

    Qin-Ming FEI; Xiao-Xing JIANG; Tong-Yi CHEN; Jun LI; Hideki MURAKAMI; Kai-Jow TSAI; William C. HUTTON

    2006-01-01

    In order to compare the difference between young and old intervertebral disc cells and their responsiveness to recombinant human bone morphogenetic protein-2 (rhBMP-2), disc cells were isolated from the anulus fibrosus (AF) and transition zones of lumbar discs from eight old and eight young New Zealand white rabbits. Compared with the cells from the young rabbits, cells from old rabbits respond less to rhBMP-2 treatment with respect to sulfated-glycosaminoglycan (sGAG) synthesis and aggrecan gene expression. But in collagen Ⅰ and collagen Ⅱ gene expressions, there are no significant differences between the old and the young. When comparing sGAG content, aggrecan, and collagen Ⅱ gene expression of the old AF cells after rhBMP-2 treatment with that of the young AF cells without rhBMP-2 treatment, the old AF cells with rhBMP-2 treatment have a greater capacity to synthesize sGAG bound in the cells and to release sGAG in the media, as well as to express aggrecan and collagen Ⅱ gene. It can be concluded that old AF cells after rhBMP-2 treatment have a greater capacity to synthesize sGAG and express aggrecan and collagen Ⅱ as compared to young AF cells without rhBMP-2 treatment. Thus rhBMP-2 can reverse the decline in the anabolic capacity of the disc cells with ageing. So it seems that rhBMP-2 has potential for use as an agent to retard a key component of disc degeneration and loss of disc matrix.

  18. Ultrastructure of inclusion bodies in annulus cells in the degenerating human intervertebral disc.

    Science.gov (United States)

    Gruber, H E; Hanley, E N

    2009-06-01

    The rough endoplasmic reticulum (rER) of the cell has an architectural editing function that checks whether protein structure and three-dimensional assembly have occurred properly prior to export of newly synthesized material out of the cell. If these have been faulty, the material is retained within the rER as an inclusion body. Inclusion bodies have been identified previously in chondrocytes and osteoblasts in chondrodysplasias and osteogenesis imperfecta. Inclusion bodies in intervertebral disc cells, however, have only recently been recognized. Our objectives were to use transmission electron microscopy to analyze more fully inclusion bodies in the annulus pulposus and to study the extracellular matrix (ECM) surrounding cells containing inclusion bodies. ECM frequently encapsulated cells with inclusion bodies, and commonly contained prominent banded aggregates of Type VI collagen. Inclusion body material had several morphologies, including relatively smooth, homogeneous material, or a rougher, less homogeneous feature. Such findings expand our knowledge of the fine structure of the human disc cell and ECM during disc degeneration, and indicate the potential utility of ultrastructural identification of discs with intracellular inclusion bodies as a screening method for molecular studies directed toward identification of defective gene products in degenerating discs.

  19. Cervical spine annulus vacuum.

    Science.gov (United States)

    Bohrer, S P; Chen, Y M

    1988-01-01

    Thirty-eight annulus vacuums in 27 patients were analyzed with regard to location, configuration, and associated vertebral abnormalities such as degenerative changes, absent and compressed anterosuperior vertebral body corners, and annulus calcification. It is concluded that most annulus vacuums are a degenerative phenomenon at the attachment of the annulus to bone. These vacuums may be associated with other degenerative changes such as osteophytes and annulus calcification. Vacuums have a strong association with compressed anterosuperior corners. These deformed corners are thought to be early osteophytes and may be related to previous trauma, a vertebra with an absent corner, and/or normal motion. Small annulus vacuums adjacent to vertebral corners with a normal appearance are more likely to result from acute trauma.

  20. Cervical spine annulus vacuum

    Energy Technology Data Exchange (ETDEWEB)

    Bohrer, S.P.; Chen, Y.M.

    1988-07-01

    Thirty-eight annulus vacuums in 27 patients were analyzed with regard to location, configuration, and associated vertebral abnormalities such as degenerative changes, absent and compressed anterosuperior vertebral body corners, and annulus calcification. It is concluded that most annulus vacuums are a degenerative phenomenon at the attachment of the annulus to bone. These vacuums may be associated with other degenerative changes such as osteophytes and annulus calcification. Vacuums have a strong association with compressed anterosuperior corners. These deformed corners are thought to be early osteophytes and may be related to previous trauma, a vertebra with an absent corner, and/or normal motion. Small annulus vacuums adjacent to vertebral corners with a normal appearance are more likely to result from acute trauma.

  1. Senescent vs. non-senescent cells in the human annulus in vivo: Cell harvest with laser capture microdissection and gene expression studies with microarray analysis

    Directory of Open Access Journals (Sweden)

    Ingram Jane A

    2010-01-01

    Full Text Available Abstract Background Senescent cells are well-recognized in the aging/degenerating human disc. Senescent cells are viable, cannot divide, remain metabolically active and accumulate within the disc over time. Molecular analysis of senescent cells in tissue offers a special challenge since there are no cell surface markers for senescence which would let one use fluorescence-activated cell sorting as a method for separating out senescent cells. Methods We employed a novel laser capture microdissection (LCM design to selectively harvest senescent and non-senescent annulus cells in paraffin-embedded tissue, and compared their gene expression with microarray analysis. LCM was used to separately harvest senescent and non-senescent cells from 11 human annulus specimens. Results Microarray analysis revealed significant differences in expression levels in senescent cells vs non-senescent cells: 292 genes were upregulated, and 321 downregulated. Genes with established relationships to senescence were found to be significantly upregulated in senescent cells vs. non-senescent cells: p38 (MPAK14, RB-Associated KRAB zinc finger, Discoidin, CUB and LCCL domain, growth arrest and DNA-damage inducible beta, p28ING5, sphingosine-1-phosphate receptor 2 and somatostatin receptor 3; cyclin-dependent kinase 8 showed significant downregulation in senescent cells. Nitric oxidase synthase 1, and heat shock 70 kDa protein 6, both of which were significantly down-regulated in senescent cells, also showed significant changes. Additional genes related to cytokines, cell proliferation, and other processes were also identified. Conclusions Our LCM-microarray analyses identified a set of genes associated with senescence which were significantly upregulated in senescent vs non-senescent cells in the human annulus. These genes include p38 MAP kinase, discoidin, inhibitor of growth family member 5, and growth arrest and DNA-damage-inducible beta. Other genes, including genes

  2. Treatment of the degenerated intervertebral disc; closure, repair and regeneration of the annulus fibrosus

    NARCIS (Netherlands)

    Sharifi, Shahriar; Bulstra, Sjoerd K.; Grijpma, Dirk W.; Kuijer, Roel

    2015-01-01

    Degeneration of the intervertebral disc (IVD) and disc herniation are two causes of low back pain. The aetiology of these disorders is unknown, but tissue weakening, which primarily occurs due to inherited genetic factors, ageing, nutritional compromise and loading history, is the basic factor causi

  3. Treatment of the degenerated intervertebral disc; closure, repair and regeneration of the annulus fibrosus

    NARCIS (Netherlands)

    Sharifi, Shahriar; Bulstra, S.K.; Grijpma, Dirk W.; Kuijer, R.

    2015-01-01

    Degeneration of the intervertebral disc (IVD) and disc herniation are two causes of low back pain. The aetiology of these disorders is unknown, but tissue weakening, which primarily occurs due to inherited genetic factors, ageing, nutritional compromise and loading history, is the basic factor

  4. On the Use of Biaxial Properties in Modeling Annulus as a Holzapfel-Gasser-Ogden Material

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    Narjes eMomeni Shahraki

    2015-06-01

    Full Text Available Besides the biology, stresses and strains within the tissue greatly influence the location of damage initiation and mode of failure in an intervertebral disc. Finite element models of a functional spinal unit (FSU that incorporate reasonably accurate geometry and appropriate material properties are suitable to investigate such issues. Different material models and techniques have been used to model the anisotropic annulus fibrosus, but the abilities of these models to predict damage initiation in the annulus and to explain clinically observed phenomena are unclear. In this study a hyperelastic anisotropic material model for the annulus with two different sets of material constants, experimentally determined using uniaxial and biaxial loading conditions, were incorporated in a 3D finite element model of a ligamentous FSU. The purpose of the study was to highlight the biomechanical differences (e.g., intradiscal pressure, motion, forces, stresses and strains, etc. due to the dissimilarity between the two sets of material properties (uniaxial and biaxial. Based on the analyses, the biaxial constants simulations resulted in better agreements with the in-vitro and in-vivo data, and thus are more suitable for future damage analysis and failure prediction of the annulus under complex multiaxial loading conditions.

  5. Extracellular matrix synthesis and ultrastructural changes of degenerative disc cells transfected by Ad/CMV-hTGF-β1

    Institute of Scientific and Technical Information of China (English)

    谭延斌; 胡有谷; 谭江威

    2003-01-01

    Objective To determine whether the synthesis of proteoglycan, collagen and associated ultrastructure are related to the adenovirus-mediated gene transferred to adult degenerative cells.Methods Adenovirus/cytomegalovirus human transforming growth fector-β1 (Ad/CMV-hTGF-β1) was used to transfect degenerative cells. Antonopulos method, Miamine method and transmission electrion microscopy were conducted to study the synthesis of proteoglycan, collagen, and ultrastructure, respectively. Cell cultures were established from the nucleus pulpous and annulus fibrosus tissues, which were taken from surgery.Results Nucleus pulpous and annulus fibrosus cells were efficiently transduced by the adenoviral vector carrying hTGF-β1 gene. The synthesis of proteoglycan and collagen increased compared with the control group (P<0.05). The metabolism of cells was slightly improved. No significant toxic effects were found.Conclusions Expression of hTGF-β1 gene is efficient to accelerates proteoglycan synthesis and thus accelerates the improvement of collagen. The function and structure of degenerative cells are improved. Ad/CMV-hTGF-β1 may be suitable for treating disc degeneration.

  6. Electroacupuncture inhibits apoptosis in annulus fibrosis cells through suppression of the mitochondria-dependent pathway in a rat model of cervical intervertebral disc degradation

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    Jun Liao

    2012-01-01

    Full Text Available The purpose of this study was to investigate whether treatment with electroacupuncture (EA inhibited mitochondria-dependent apoptosis in annulus fibrosis (AF cells in a rat model of cervical intervertebral disc degradation induced by unbalanced dynamic and static forces. Forty Sprague-Dawley rats were used in this study, of which 30 underwent surgery to induce cervical intervertebral disc degradation, 10 rats received EA at acupoints Dazhui (DU 14 and Shousanli (LI 10. TUNEL staining was measured to assess apoptosis in AF cells, immunohistochemistry was used to examine Bcl-2 and Bax expression, colorimetric assays were used to determine caspase 9 and caspase 3 activities and RT-PCR and western blotting were used to assess the mRNA and protein expression of Crk and ERK2. Treatment with EA reduced the number of AF-positive cells in TUNEL staining, increased Bcl-2-positive cells and decreased Bax-positive cells in immunohistochemical staining, significantly inhibited the activation of caspases-9 and -3, and enhanced the mRNA and protein expression of Crk and ERK2. Our data show that EA inhibits AF cell apoptosis via the mitochondria-dependent pathway and up-regulates Crk and ERK2 expression. These results suggest that treatment with may be a good alternative therapy for preventing cervical spondylosis.

  7. Absence of annulus in human asthenozoospermia: case report.

    Science.gov (United States)

    Lhuillier, P; Rode, B; Escalier, D; Lorès, P; Dirami, T; Bienvenu, T; Gacon, G; Dulioust, E; Touré, A

    2009-06-01

    The annulus is a septin-based ring structure located at the junction of the midpiece (MP) and the principal piece (PP) of spermatozoa flagellum. In the mouse, deletion of Septin 4, a structural component of the sperm annulus, prevents annulus formation and leads to MP-PP disjunction, flagellar bending, asthenozoospermia and male sterility. Testis anion transporter 1 (Tat1) is a germ cell-specific member of the SLC26 anion transporter family and is co-expressed with Septin 4 at the sperm annulus. Interestingly, Tat1 null sperm bear an atrophic annulus, causing a phenotype similar to that of Sept4 null sperm. We searched for Tat1 misexpression and/or mislocalization in spermatozoa from asthenozoospermic subjects (n = 75) and controls by performing an immunofluorescence detection assay on sperm smear preparations. We found one patient showing moderate asthenozoospermia, with 97% of sperm lacking Tat1, Septin 4 and Septin 7 proteins at the annulus. We confirmed the absence of the annulus structure by transmission electron microscopy and observed that spermatozoa from the patient displayed MP-PP disjunction and abnormal mitochondrial organization. We show that the structural defects in sperm are not caused by abnormal transcription or point mutations of the TAT1 and SEPT4 genes; however, although both proteins are expressed, they are not properly localized at sperm annulus. The case we studied, so far unreported in human, confirms the involvement of Tat1 and Septin proteins in the constitution of the annulus, but also raises questions about the function of this structure in human sperm motility.

  8. Mesenchymal Stem Cell Levels of Human Spinal Tissues.

    Science.gov (United States)

    Harris, Liam; Vangsness, C Thomas

    2017-09-06

    .: Systematic Review. .: The aim of this study was to investigate, quantify, compare and compile the various mesenchymal stem cell tissue sources within human spinal tissues to act as a compendium for clinical and research application. .: Recent years have seen a dramatic increase in academic and clinical understanding of human mesenchymal stem cells (MSCs). Previously limited to cells isolated from bone marrow, the past decade has illicited the characterization and isolation of human MSCs from adipose, bone marrow, synovium, muscle, periosteum, peripheral blood, umbilical cord, placenta and numerous other tissues. As researchers explore practical applications of cells in these tissues, the absolute levels of MSCs in specific spinal tissue will be critical to guide future research. .: The PubMED, MEDLINE, EMBASE and Cochrane databases were searched for articles relating to the harvest, characterization, isolation and quantification of human mesenchymal stem cells from spinal tissues. Selected articles were examined for relevant data, categorized according to type of spinal tissue, and when possible, standardized to facilitate comparisons between sites. .: Human mesenchymal stem cell levels varied widely between spinal tissues. Yields for Intervertebral disc demonstrated roughly 5% of viable cells to be positive for MSC surface markers. Cartilage endplate cells yielded 18,500- 61,875 cells/ 0.8 mm thick sample of cartilage end plate. Ligamentum flavum yielded 250,000- 500,000 cells per gram of tissue. Annulus fibrosus FACS treatment found 29% of cells positive for MSC marker Stro-1. Nucleus pulposus yielded mean tissue samples of 40,584-234,137 MSCs/gram of tissue. .: Numerous tissues within and surrounding the spine represent a consistent and reliable source for the harvest and isolation of human mesenchymal stem cells. Among the tissues of the spine, the annulus fibrosus and ligamentum flavum each offer considerable levels of mesenchymal stem cells, and may

  9. The Annulus Property of Simple Holomorphic Discs

    CERN Document Server

    Zehmisch, Kai

    2010-01-01

    We show that any simple holomorphic disc admits the annulus property, i.e., each interior point is surrounded by an arbitrary small annulus consisting entirely of injective points. As an application we show that interior singularities of holomorphic discs can be resolved after slight perturbation of the involved almost complex structure. Moreover, for boundary points the analogue notion, the half-annulus property, is introduced and studied in detail.

  10. The annulus property of simple holomorphic discs

    OpenAIRE

    Zehmisch, Kai

    2013-01-01

    We show that any simple holomorphic disc admits the annulus property, i.e., each interior point is surrounded by an arbitrary small annulus consisting entirely of injective points. As an application we show that interior singularities of holomorphic discs can be resolved after slight perturbation of the almost complex structure. Moreover, for boundary points the analogue notion, the half-annulus property, is introduced and studied in detail.

  11. Evaluation of apoptotic cell death in normal and chondrodystrophic canine intervertebral discs

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    Marie Klauser

    2012-02-01

    Full Text Available Disc degeneration occurs commonly in dogs. A variety of factors is thought to contribute an inappropriate disc matrix that isolate cells in the disc and lead to apoptosis. Disc herniation with radiculopathy and discogenic pain are the results of the degenerative process. The objective of this prospective study was to determine the extent of apoptosis in intact and herniated intervertebral discs of chondrodystrophic dogs and non-chondrodystrophic dogs. In addition, the nucleus pulposus (NP was histologically compared between non-chondrodystrophic and chondrodystrophic dogs. Thoracolumbar intervertebral discs and parts of the extruded nucleus pulposus were harvested from 45 dogs. Samples were subsequently stained with haematoxylin-eosin and processed to detect cleaved caspase-3 and poly(ADP-ribose polymerase. A significant greater degree of apoptosis was observed in herniated NPs of chondrodystrophic dogs compared to non- chondrodystrophic dogs with poly (ADP-ribose polymerase and cleaved caspase- 3 detection. Within the group of chondrodystrophic dogs, dogs with an intact disc and younger than 6 years showed a significant lower incidence of apoptosis in the NP compared to the herniated NP of chondrodystrophic dogs. The extent of apoptosis in the annulus fibrosus was not different between the intact disc from chondrodystrophic and non- chondrodystrophic dogs. An age-related increase of apoptotic cells in NP and annulus fibrosus was found in the intact non-herniated intervertebral discs. Histologically, absence of notochordal cells and occurrence of chondroid metaplasia were observed in the nucleus pulposus of chondrodystrophic dogs. As a result, we found that apoptosis plays a role in disc degeneration in chondrodystrophic dogs.

  12. Functional myelographic differentiation of lumbar bulging annulus

    Energy Technology Data Exchange (ETDEWEB)

    Park, Choong Ki; Kim, Hong Kil; Park, Sang Gyu; Lee, Young Jung; Yoon, Jong Sup [Hallym University College of Medicine, Seoul (Korea, Republic of)

    1988-08-15

    Herniated disk and bulging annulus are the major causes of lower back pain. It is necessary to differentiate bulging annulus from herniated disk because of their different methods of treatment. Myelography is one of the useful diagnostic methods for disk diseases even though advanced diagnostic modalities such as CT and MRI are more accurate. Functional myelography is not a new technology expect for two additional views, flexion and extension, are obtained with conventional myelography. Differentiation between bulging annulus and herniated disk by conventional myelography is based on the extent and multiplicity of extradural deformity of the contrast filled dural sac and neural sleeve as well as the changes of nerve root. There is no previous report about differential points between bulging annulus and herniated disk according to functional myelography. It is the purpose of this study to find any additional differential points on functional myelography between bulging annulus and herniated disk over convectional myelography. Authors analysed functional myelographic findings of 152 cases from July 1986 to July 1987. Among them, 22 cases who had been suffered from cervical abnormality or vague lower back pain were diagnosed as normal by myelography, and 30 cases of L4-5 herniated disk and 21 cases of L4-5 bulging annulus which had been finally diagnosed by operation were studied. The results were as follows. 1. In normal group, anterior epidural space was gradually widened from the upper lumbar vertebra downward. And anterior epidural space was more sidened at the disk level in extension view than in flexion except for L5-S1 lever. 2. In bulging annulus group, the shape of anterior epidural space in flexion state was as similar as normal. Anoterior epidural space in extension state was more sidened at the buldging annulus than normal, but lesser than herniated disk. 3. In herniated disk group, widening of anterior epidural space at the herniated disk level was

  13. Local Casimir Energies for an Annulus

    CERN Document Server

    Cavero-Pelaez, I; Wagner, J; Cavero-Pelaez, Ines; Milton, Kimball A.; Wagner, Jeffrey

    2005-01-01

    The local Casimir energy density for a massless scalar field associated with step-function potentials in a 3+1 dimensional spherical geometry is considered. The potential is chosen to be zero except in an annulus of thickness $\\delta$, where it has height $h$, $h\\delta=1$. In the limit of zero thickness, an ideal $\\delta$-function shell is recovered. The behavior of the energy density as the surface of the annulus is approached is studied in both the strong and weak coupling regimes. The former case corresponds to the well-known Dirichlet shell limit. New results, which shed light on the nature of surface divergences and on the energy contained within the annulus, are obtained in the weak coupling limit. In that case, the energy has a contribution not only from the local energy density, but from an energy term residing entirely on the surface. It is shown that the latter coincides with the integrated local energy density within the annulus. We also study the dependence of local and global quantities on the co...

  14. Rarefied gas flow in a cylindrical annulus

    Science.gov (United States)

    Lo, S. S.; Loyalka, S. K.; Storvick, T. S.

    1983-09-01

    The Hansen-Morse model of the linearized Wang Chang-Uhlenbeck equation is used to study the thermal transpiration and mechanocaloric effects for rarefied polyatomic gases in a cylindrical annulus, where boundary conditions are characterized by diffuse reflection. Phenomenological coefficients at all degrees of rarefaction are reported for physical parameters that represent helium, hydrogen, carbon dioxide, and air. Comparisons with isothermal flow data are given.

  15. Comparison of three approaches for defining nucleus pulposus and annulus fibrosus on sagittal magnetic resonance images of the lumbar spine

    Directory of Open Access Journals (Sweden)

    Greta S.P. Mok

    2016-07-01

    Conclusion: The 5-/7-ROI methods agreed with the M-ROI approach for NP selection, while the agreement with AF was moderate to poor, with the 5-ROI method showing slight advantage over the 7-ROI method. Cautions should be taken to interpret the MR relaxometry findings when 5-/7-ROI methods are used to select AF.

  16. Modeling mantle convection in the spherical annulus

    Science.gov (United States)

    Hernlund, John W.; Tackley, Paul J.

    2008-12-01

    Most methods for modeling mantle convection in a two-dimensional (2D) circular annular domain suffer from innate shortcomings in their ability to capture several characteristics of the spherical shell geometry of planetary mantles. While methods such as rescaling the inner and outer radius to reduce anomalous effects in a 2D polar cylindrical coordinate system have been introduced and widely implemented, such fixes may have other drawbacks that adversely affect the outcome of some kinds of mantle convection studies. Here we propose a new approach that we term the "spherical annulus," which is a 2D slice that bisects the spherical shell and is quantitatively formulated at the equator of a spherical polar coordinate system after neglecting terms in the governing equations related to variations in latitude. Spherical scaling is retained in this approximation since the Jacobian function remains proportional to the square of the radius. We present example calculations to show that the behavior of convection in the spherical annulus compares favorably against calculations performed in other 2D annular domains when measured relative to those in a fully three-dimensional (3D) spherical shell.

  17. Asymptotic Analysis of Transport Equation in Annulus

    Science.gov (United States)

    Wu, Lei; Yang, Xiongfeng; Guo, Yan

    2016-09-01

    We consider the diffusive limit of a steady neutron transport equation with one-speed velocity in a two-dimensional annulus. A classical theorem in Bensoussan et al. (Publ Res Inst Math Sci 15:53-157, 1979) states that the solution can be approximated in L^{∞} by the sum of the interior solution and Knudsen layer derived from Milne problem. However, this result was disproved in Wu and Guo (Commun Math Phys 336:1473-1553, 2015) in a plate via a different boundary layer expansion with geometric correction. In this paper, we established the diffusive limit and provide a counterexample to Bensoussan et al. (1979) in non-convex domains.

  18. COMPARISON OF PREOPERATIVE NONINVASIVE AND INTRAOPERATIVE MEASUREMENTS OF AORTIC ANNULUS

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    Manish Hinduja

    2016-10-01

    Full Text Available BACKGROUND Precise preoperative assessment of aortic annulus diameter is essential for sizing of aortic valve especially in patients planned for transcatheter aortic valve replacement. Computed Tomographic (CT and echocardiographic measurements of the aortic annulus vary because of elliptical shape of aortic annulus. This study was undertaken to compare the measurement of aortic annulus intraoperatively with preoperative noninvasive methods in patients undergoing aortic valve replacement. MATERIALS AND METHODS Aortic annulus diameter was measured with cardiac CT and Transesophageal Echocardiography (TEE prior to open aortic valve replacement in 30 patients with aortic valve stenosis. In CT, aortic annulus dimensions were measured in coronal plane, sagittal oblique plane and by planimetry. Both 2-dimensional and 3-dimensional TEE were used. These were compared with intraoperative measurements done by valve sizers and Hegar dilators. Pearson analysis was applied to test for degree of correlation. RESULTS CT in coronal and sagittal oblique plane tends to overestimate the diameter of aortic annulus when compared with intraoperative measurements (coefficient of relation, r = 0.798 and 0.749, respectively. CT measurements in single oblique plane showed a weaker correlation with intraoperative measurements than 3D TEE and 2D TEE (r = 0.917 and 0.898, respectively. However, CT measurements by planimetry method were most correlating with the intraoperative measurements (r = 0.951. CONCLUSION Noninvasive investigations with 3-dimensional views (CT-based measurement employing calculated average diameter assessment by planimetry and 3-dimensional TEE showed better correlation with intraoperative measurement of aortic annulus. CT-based aortic annulus measurement by planimetry seems to provide adequate dimensions most similar to operative measurements.

  19. Organotypic Cultures of Intervertebral Disc Cells: Responses to Growth Factors and Signaling Pathways Involved

    Directory of Open Access Journals (Sweden)

    Harris Pratsinis

    2015-01-01

    Full Text Available Intervertebral disc (IVD degeneration is strongly associated with low back pain, a major cause of disability worldwide. An in-depth understanding of IVD cell physiology is required for the design of novel regenerative therapies. Accordingly, aim of this work was the study of IVD cell responses to mitogenic growth factors in a three-dimensional (3D organotypic milieu, comprising characteristic molecules of IVD’s extracellular matrix. In particular, annulus fibrosus (AF cells were cultured inside collagen type-I gels, while nucleus pulposus (NP cells in chondroitin sulfate A (CSA supplemented collagen gels, and the effects of Platelet-Derived Growth Factor (PDGF, basic Fibroblast Growth Factor (bFGF, and Insulin-Like Growth Factor-I (IGF-I were assessed. All three growth factors stimulated DNA synthesis in both AF and NP 3D cell cultures, with potencies similar to those observed previously in monolayers. CSA supplementation inhibited basal DNA synthesis rates, without affecting the response to growth factors. ERK and Akt were found to be phosphorylated following growth factor stimulation. Blockade of these two signaling pathways using pharmacologic inhibitors significantly, though not completely, inhibited growth factor-induced DNA synthesis. The proposed culture systems may prove useful for further in vitro studies aiming at future interventions for IVD regeneration.

  20. Small aortic valve annulus in children with fixed subaortic stenosis.

    Science.gov (United States)

    Thilenius, O G; Campbell, D; Bharati, S; Lev, M; Arcilla, R A

    1989-01-01

    Twenty-one hearts with fixed subaortic stenosis (FSAS) were examined pathologically. Thirty children with no hemodynamically significant heart disease, 31 children with valvar aortic stenosis, and 25 children with FSAS were studied by echo- and angiocardiography. The following conclusions were drawn: (1) Patients with FSAS often have abnormal aortic valve leaflets as well as small aortic valve annulus. (2) A small aortic annulus/descending aorta ratio is probably present at birth, and may decrease with increasing age. (3) In some patients with FSAS the aortic valve annulus is too small for simple resection of the fibroelastic tissue. A Konno operation is needed for these patients. (4) M-mode echocardiography has not been useful in identifying abnormally small aortic valve annulus in FSAS patients.

  1. Role of Mitral Annulus Diastolic Geometry on Intraventricular Filling Dynamics.

    Science.gov (United States)

    Okafor, Ikechukwu U; Santhanakrishnan, Arvind; Raghav, Vrishank S; Yoganathan, Ajit P

    2015-12-01

    The mitral valve (MV) is a bileaflet valve positioned between the left atrium and ventricle of the heart. The annulus of the MV has been observed to undergo geometric changes during the cardiac cycle, transforming from a saddle D-shape during systole to a flat (and less eccentric) D-shape during diastole. Prosthetic MV devices, including heart valves and annuloplasty rings, are designed based on these two configurations, with the circular design of some prosthetic heart valves (PHVs) being an approximation of the less eccentric, flat D-shape. Characterizing the effects of these geometrical variations on the filling efficiency of the left ventricle (LV) is required to understand why the flat D-shaped annulus is observed in the native MV during diastole in addition to optimizing the design of prosthetic devices. We hypothesize that the D-shaped annulus reduces energy loss during ventricular filling. An experimental left heart simulator (LHS) consisting of a flexible-walled LV physical model was used to characterize the filling efficiency of the two mitral annular geometries. The strength of the dominant vortical structure formed and the energy dissipation rate (EDR) of the measured fields, during the diastolic period of the cardiac cycle, were used as metrics to quantify the filling efficiency. Our results indicated that the O-shaped annulus generates a stronger (25% relative to the D-shaped annulus) vortical structure than that of the D-shaped annulus. It was also found that the O-shaped annulus resulted in higher EDR values throughout the diastolic period of the cardiac cycle. The results support the hypothesis that a D-shaped mitral annulus reduces dissipative energy losses in ventricular filling during diastole and in turn suggests that a symmetric stent design does not provide lower filling efficiency than an equivalent asymmetric design.

  2. Stability of fluid flow in a cylindrical annulus

    Science.gov (United States)

    Ludwieg, H.

    1984-01-01

    Helical flow in an annulus between two coaxial cylinders is investigated with regard to its stability against the formation of helical vortices of the type known as Taylor's annular vortices. Assuming the annulus to be small and the velocities to vary linearly with radius, it is shown that the problem can be reduced to the classical case of flow between two rotating cylinders. An appropriate stability criterion for helical flows is derived from Rayleigh's stability criterion applicable to such flows.

  3. Caseous Necrosis of Mitral Annulus: A Rare Cause of Stroke

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    Jérôme Corre

    2013-01-01

    Full Text Available The current report describes a rare case of a caseous necrosis presenting as a pseudotumor in ventricle, revealed by stroke. Cerebral MRI, showing multiples lacunes, evocates a cardioembolic mechanism. Transthoracic and transesophageal echocardiography demonstrate a large hyperechogenic mass fixed to the posterior mitral valve and annulus while thoracic tomography revealed a fully calcified lesion, at the mitral annulus, evocative of caseus necrosis. Medical therapy was preferred (anticoagulation, because of her age and the decaying nature of surgery.

  4. Loewner Theory in annulus II: Loewner chains

    CERN Document Server

    Contreras, Manuel D; Gumenyuk, Pavel

    2011-01-01

    Loewner Theory, based on dynamical viewpoint, proved itself to be a powerful tool in Complex Analysis and its applications. Recently Bracci et al [Bracci et al, to appear in J. Reine Angew. Math. Available on ArXiv 0807.1594; Bracci et al, Math. Ann. 344(2009), 947--962; Contreras et al, Revista Matematica Iberoamericana 26(2010), 975--1012] have proposed a new approach bringing together all the variants of the (deterministic) Loewner Evolution in a simply connected reference domain. This paper is devoted to the construction of a general version of Loewner Theory for the annulus launched in [ArXiv 1011.4253]. We introduce the general notion of a Loewner chain over a system of annuli and obtain a 1-to-1 correspondence between Loewner chains and evolution families in the doubly connected setting similar to that in the Loewner Theory for the unit disk. Futhermore, we establish a conformal classification of Loewner chains via the corresponding evolution families and via semicomplete weak holomorphic vector fields...

  5. Nucleus pulposus cell-matrix interactions with laminins.

    Science.gov (United States)

    Gilchrist, C L; Francisco, A T; Plopper, G E; Chen, J; Setton, L A

    2011-06-20

    The cells of the nucleus pulposus (NP) region of the intervertebral disc play a critical role in this tissue's generation and maintenance, and alterations in NP cell viability, metabolism, and phenotype with aging may be key contributors to progressive disc degeneration. Relatively little is understood about the phenotype of NP cells, including their cell-matrix interactions which may modulate phenotype and survival. Our previous work has identified strong and region-specific expression of laminins and laminin cell-surface receptors in immature NP tissues, suggesting laminin cell-matrix interactions are uniquely important to the biology of NP cells. Whether these observed tissue-level laminin expression patterns reflect functional adhesion behaviors for these cells is not known. In this study, we examined NP cell-matrix interactions with specific matrix ligands, including various laminin isoforms, using quantitative assays of cell attachment, spreading, and adhesion strength. NP cells were found to attach in higher numbers and exhibited rapid cell spreading and higher resistance to detachment force on two laminin isoforms (LM-511,LM-332) identified to be uniquely expressed in the NP region, as compared to another laminin isoform (LM-111) and several other matrix ligands (collagen, fibronectin). Additionally, NP cells were found to attach in higher numbers to laminins as compared to cells isolated from the disc's annulus fibrosus region. These findings confirm that laminin and laminin receptor expression documented in NP tissues translates into unique functional NP cell adhesion behaviors that may be useful tools for in vitro cell culture and biomaterials that support NP cells.

  6. Nucleus pulposus cell-matrix interactions with laminins

    Directory of Open Access Journals (Sweden)

    CL Gilchrist

    2011-06-01

    Full Text Available The cells of the nucleus pulposus (NP region of the intervertebral disc play a critical role in this tissue’s generation and maintenance, and alterations in NP cell viability, metabolism, and phenotype with aging may be key contributors to progressive disc degeneration. Relatively little is understood about the phenotype of NP cells, including their cell-matrix interactions which may modulate phenotype and survival. Our previous work has identified strong and region-specific expression of laminins and laminin cell-surface receptors in immature NP tissues, suggesting laminin cell-matrix interactions are uniquely important to the biology of NP cells. Whether these observed tissue-level laminin expression patterns reflect functional adhesion behaviors for these cells is not known. In this study, we examined NP cell-matrix interactions with specific matrix ligands, including various laminin isoforms, using quantitative assays of cell attachment, spreading, and adhesion strength. NP cells were found to attach in higher numbers and exhibited rapid cell spreading and higher resistance to detachment force on two laminin isoforms (LM-511,LM-332 identified to be uniquely expressed in the NP region, as compared to another laminin isoform (LM-111 and several other matrix ligands (collagen, fibronectin. Additionally, NP cells were found to attach in higher numbers to laminins as compared to cells isolated from the disc’s annulus fibrosus region. These findings confirm that laminin and laminin receptor expression documented in NP tissues translates into unique functional NP cell adhesion behaviors that may be useful tools for in vitro cell culture and biomaterials that support NP cells.

  7. Tricuspid annulus: A spatial and temporal analysis

    Directory of Open Access Journals (Sweden)

    Ziyad O Knio

    2016-01-01

    Full Text Available Background: Traditional two-dimensional (2D echocardiographic evaluation of tricuspid annulus (TA dilation is based on single-frame measurements of the septolateral (S-L dimension. This may not represent either the axis or the extent of dynamism through the entire cardiac cycle. In this study, we used real-time 3D transesophageal echocardiography (TEE to analyze geometric changes in multiple axes of the TA throughout the cardiac cycle in patients without right ventricular abnormalities. Materials and Methods: R-wave-gated 3D TEE images of the TA were acquired in 39 patients undergoing cardiovascular surgery. The patients with abnormal right ventricular/tricuspid structure or function were excluded from the study. For each patient, eight points along the TA were traced in the 3D dataset and used to reconstruct the TA at four stages of the cardiac cycle (end- and mid-systole, end- and mid-diastole. Statistical analyses were applied to determine whether TA area, perimeter, axes, and planarity changed significantly over each stage of the cardiac cycle. Results: TA area (P = 0.012 and perimeter (P = 0.024 both changed significantly over the cardiac cycle. Of all the axes, only the posterolateral-anteroseptal demonstrated significant dynamism (P < 0.001. There was also a significant displacement in the vertical axis between the points and the regression plane in end-systole (P < 0.001, mid-diastole (P = 0.014, and mid-systole (P < 0.001. Conclusions: The TA demonstrates selective dynamism over the cardiac cycle, and its axis of maximal dynamism is different from the axis (S-L that is routinely measured with 2D TEE.

  8. Running Exercise Alleviates Pain and Promotes Cell Proliferation in a Rat Model of Intervertebral Disc Degeneration

    Directory of Open Access Journals (Sweden)

    Shuo Luan

    2015-01-01

    Full Text Available Chronic low back pain accompanied by intervertebral disk degeneration is a common musculoskeletal disorder. Physical exercise, which is clinically recommended by international guidelines, has proven to be effective for degenerative disc disease (DDD patients. However, the mechanism underlying the analgesic effects of physical exercise on DDD remains largely unclear. The results of the present study showed that mechanical withdrawal thresholds of bilateral hindpaw were significantly decreased beginning on day three after intradiscal complete Freund’s adjuvant (CFA injection and daily running exercise remarkably reduced allodynia in the CFA exercise group beginning at day 28 compared to the spontaneous recovery group (controls. The hindpaw withdrawal thresholds of the exercise group returned nearly to baseline at the end of experiment, but severe pain persisted in the control group. Histological examinations performed on day 70 revealed that running exercise restored the degenerative discs and increased the cell densities of the annulus fibrosus (AF and nucleus pulposus (NP. Furthermore, immunofluorescence labeling revealed significantly higher numbers of 5-bromo-2-deoxyuridine (BrdU-positive cells in the exercise group on days 28, 42, 56 and 70, which indicated more rapid proliferation compared to the control at the corresponding time points. Taken together, these results suggest that running exercise might alleviate the mechanical allodynia induced by intradiscal CFA injection via disc repair and cell proliferation, which provides new evidence for future clinical use.

  9. Changes of number of cells expressing proliferation and progenitor cell markers with age in rabbit intervertebral discs

    Institute of Scientific and Technical Information of China (English)

    Miersalijiang Yasen; Qinming Fei; William C Hutton; Jian Zhang; Jian Dong; Xiaoxing Jiang; Feng Zhang

    2013-01-01

    Basic knowledge about the normal regeneration process within the intervertebral disc (IVD) is important to the understanding of the underlying biology.The presence of progenitor and stem cells in IVD has been verified.However,changes of number of progenitor and stem cells with age are still unknown.In this study,changes of cell proliferation and progenitor cell markers with age in IVD cells from rabbits of two different ages were investigated using flow cytometry,immunohistochemistry,real-time polymerase chain reaction,and western blot analysis.Proliferating cell nuclear antigen (PCNA) was chosen as a marker for proliferation,and Notch1,Jagged1,C-KIT,CD166 were chosen as stem/progenitor cell markers.Cell cycle analysis showed that cell number in the G2/M phase of the young rabbits was significantly higher than that of mature rabbits.Immunohistochemical staining demonstrated the expression of PCNA,C-KIT,CD166,Notch1,and Jagged1 in both young and mature annulus fibrosus (AF).Protein expressions of these cell markers in the young rabbits were all significantly higher than those in the mature rabbits.The expression levels of PCNA,CD166,C-KIT,Jagged1 were significantly higher in the AF,and PCNA,C-KIT in the nucleus pulposus from young rabbits than those from the mature rabbits.These findings demonstrated that both proliferation and progenitor cells exist in rabbit IVDs and the number of cells expressing proliferation and progenitor cell markers decreases with age in the rabbit IVD cells.Methods that are designed to maintain the endogenous progenitor cells and stimulate their proliferation could be successful in preventing or inhibiting degenerative disc disease.

  10. Flow of viscoplastic fluids in a rotating concentric annulus

    DEFF Research Database (Denmark)

    Hassager, Ole; Bittleston, Simon H.

    1992-01-01

    pressure gradient is small compared to the yield stress of the fluid then the full solution predicts the existence of plugs attached to the outer wall of the annulus. The slot approximation fails to predict this feature. For larger pressure gradients the two solutions are in good agreement. The analytical......A difficulty in any flow calculation with viscoplastic fluids such as Bingham fluids is the determination of possible plug zones in which no deformation occurs. This paper investigates the flow in a concentric annulus when there is both an axial and tangential flow, the tangent flow arising from...... rotation of the inner cylinder of the annulus. The flow is analyzed by considering flow in a slot, for which an analytical solution is given, and by solving the full problem numerically. It is shown that when the boundary is set in motion an applied pressure gradient will always cause flow. If the applied...

  11. Nucleate boiling pressure drop in an annulus: Book 3

    Energy Technology Data Exchange (ETDEWEB)

    Block, J.A.; Crowley, C.; Dolan, F.X.; Sam, R.G.; Stoedefalke, B.H.

    1992-11-01

    The application of the work described in this report is the production reactors at the Savannah River Site, and the context is nuclear reactor safety. The Loss of Coolant Accident (LOCA) scenario considered involves a double-ended break of a primary coolant pipe in the reactor. During a LOCA, the flow through portions of the reactor may reverse direction or be greatly reduced, depending upon the location of the break. The reduced flow rate of coolant (D{sub 2}O) through the fuel assembly channels of the reactor -- downflow in this situation -- can lead to boiling and to the potential for flow instabilities which may cause some of the fuel assembly channels to overheat and melt. That situation is to be avoided. The experimental approach is to provide a test annulus which simulates geometry, materials, and flow conditions in a Mark-22 fuel assembly (Coolant Channel 3) to the extent possible. The annulus has a full-scale geometry, and in fat uses SRL dummy hardware for the inner annulus wall in the ribbed geometry. The materials aluminum. The annulus is uniformly heated in the axial direction, but the circumferential heat flux can be varied to provide ``power tilt`` or asymmetric heating of the inner and outer annulus walls. The test facility uses H{sub 2}O rather than D{sub 2}O, but it includes the effects of dissolved helium gas present in the reactor. The key analysis approaches are: To compare the minima in the measured demand curves with analytical criteria, in particular the Saha-Zuber (1974) model; and to compare the pressure and temperature as a function of length in the annulus with an integral model for flow boiling in a heated channel. This document consists of data plots and summary files of temperature measurements.

  12. Nucleate boiling pressure drop in an annulus: Book 6

    Energy Technology Data Exchange (ETDEWEB)

    1992-11-01

    The application of the work described in this report is the production reactors at the Savannah River Site, and the context is nuclear reactor safety. The Loss of Coolant Accident (LOCA) scenario considered involves a double-ended break of a primary coolant pipe in the reactor. During a LOCA, the flow through portions of the reactor may reverse direction or be greatly reduced, depending upon the location of the break. The reduced flow rate of coolant (D{sub 2}O) through the fuel assembly channels of the reactor -- downflow in this situation -- can lead to boiling and to the potential for flow instabilities which may cause some of the fuel assembly channels to overheat and melt. That situation is to be avoided. The experimental approach is to provide a test annulus which simulates geometry, materials, and flow conditions in a Mark-22 fuel assembly (Coolant Channel 3) to the extent possible. The annulus has a full-scale geometry, and in fat uses SRL dummy hardware for the inner annulus wall in the ribbed geometry. The materials aluminum. The annulus is uniformly heated in the axial direction, but the circumferential heat flux can be varied to provide ``power tilt`` or asymmetric heating of the inner and outer annulus walls. The test facility uses H{sub 2}O rather than D{sub 2}O, but it includes the effects of dissolved helium gas present in the reactor. The key analysis approaches are: To compare the minima in the measured demand curves with analytical criteria, in particular the Saha-Zuber (1974) model; and to compare the pressure and temperature as a function of length in the annulus with an integral model for flow boiling in a heated channel. This document consists of a summary of temperature measurements to include recorded minima, maxima, averages and standard deviations.

  13. Nucleate boiling pressure drop in an annulus: Book 4

    Energy Technology Data Exchange (ETDEWEB)

    Block, J.A.; Crowley, C.; Dolan, F.X.; Sam, R.G.; Stoedefalke, B.H.

    1992-11-01

    The application of the work described in this report is the production reactors at the Savannah River Site, and the context is nuclear reactor safety. The Loss of Coolant Accident (LOCA) scenario considered involves a double-ended break of a primary coolant pipe in the reactor. During a LOCA, the flow through portions of the reactor may reverse direction or be greatly reduced, depending upon the location of the break. The reduced flow rate of coolant (D{sub 2}O) through the fuel assembly channels of the reactor -- downflow in this situation -- can lead to boiling and to the potential for flow instabilities which may cause some of the fuel assembly channels to overheat and melt. That situation is to be avoided. The experimental approach is to provide a test annulus which simulates geometry, materials, and flow conditions in a Mark-22 fuel assembly (Coolant Channel 3) to the extent possible. The annulus has a full-scale geometry, and in fat uses SRL dummy hardware for the inner annulus wall in the ribbed geometry. The materials aluminum. The annulus is uniformly heated in the axial direction, but the circumferential heat flux can be varied to provide ``power tilt`` or asymmetric heating of the inner and outer annulus walls. The test facility uses H{sub 2}O rather than D{sub 2}O, but it includes the effects of dissolved helium gas present in the reactor. The key analysis approaches are: To compare the minima in the measured demand curves with analytical criteria, in particular the Saha-Zuber (1974) model; and to compare the pressure and temperature as a function of length in the annulus with an integral model for flow boiling in a heated channel. This document consists of data plots and summary files of temperature measurements.

  14. Nucleate boiling pressure drop in an annulus: Book 2

    Energy Technology Data Exchange (ETDEWEB)

    Block, J.A.; Crowley, C.; Dolan, F.X.; Sam, R.G.; Stoedefalke, B.H.

    1992-11-01

    The application of the work described in this report is the production reactors at the Savannah River Site, and the context is nuclear reactor safety. The Loss of Coolant Accident (LOCA) scenario considered involves a double-ended break of a primary coolant pipe in the reactor. During a LOCA, the flow through portions of the reactor may reverse direction or be greatly reduced, depending upon the location of the break. The reduced flow rate of coolant (D{sub 2}O) through the fuel assembly channels of the reactor -- downflow in this situation -- can lead to boiling and to the potential for flow instabilities which may cause some of the fuel assembly channels to overheat and melt. That situation is to be avoided. The experimental approach is to provide a test annulus which simulates geometry, materials, and flow conditions in a Mark-22 fuel assembly (Coolant Channel 3) to the extent possible. The annulus has a full-scale geometry, and in fat uses SRL dummy hardware for the inner annulus wall in the ribbed geometry. The materials aluminum. The annulus is uniformly heated in the axial direction, but the circumferential heat flux can be varied to provide ``power tilt`` or asymmetric heating of the inner and outer annulus walls. The test facility uses H{sub 2}O rather than D{sub 2}O, but it includes the effects of dissolved helium gas present in the reactor. The key analysis approaches are: To compare the minima in the measured demand curves with analytical criteria, in particular the Saha-Zuber (1974) model; and to compare the pressure and temperature as a function of length in the annulus with an integral model for flow boiling in a heated channel. Nineteen test series and a total of 178 tests were performed. Testing addressed the effects of: Heat flux; pressure; helium gas; power tilt; ribs; asymmetric heat flux.

  15. Nucleate boiling pressure drop in an annulus: Book 8

    Energy Technology Data Exchange (ETDEWEB)

    1992-11-01

    The application of the work described in this report is the production reactors at the Savannah River Site, and the context is nuclear reactor safety. The Loss of Coolant Accident (LOCA) scenario considered involves a double-ended break of a primary coolant pipe in the reactor. During a LOCA, the flow through portions of the reactor may reverse direction or be greatly reduced, depending upon the location of the break. The reduced flow rate of coolant (D{sub 2}O) through the fuel assembly channels of the reactor -- downflow in this situation -- can lead to boiling and to the potential for flow instabilities which may cause some of the fuel assembly channels to overheat and melt. That situation is to be avoided. The experimental approach is to provide a test annulus which simulates geometry, materials, and flow conditions in a Mark-22 fuel assembly (Coolant Channel 3) to the extent possible. The annulus has a full-scale geometry, and in fat uses SRL dummy hardware for the inner annulus wall in the ribbed geometry. The materials aluminum. The annulus is uniformly heated in the axial direction, but the circumferential heat flux can be varied to provide ``power tilt`` or asymmetric heating of the inner and outer annulus walls. The test facility uses H{sub 2}O rather than D{sub 2}O, but it includes the effects of dissolved helium gas present in the reactor. The key analysis approaches are: To compare the minima in the measured demand curves with analytical criteria, in particular the Saha-Zuber (1974) model; and to compare the pressure and temperature as a function of length in the annulus with an integral model for flow boiling in a heated channel. This document consists of tables of temperature measurements.

  16. Flow in a small annulus between concentric cylinders

    Energy Technology Data Exchange (ETDEWEB)

    Luecke, M.; Mihelcic, M.; Wingerath, K. (Kernforschungsanlage Juelich G.m.b.H. (Germany, F.R.). Inst. fuer Festkoerperforschung); Pfister, G. (Kiel Univ. (Germany, F.R.). Inst. fuer Angewandte Physik)

    1984-03-01

    Rotationally symmetric vortex flows between concentric cylinders with the inner one rotating and the outer one at rest have been investigated by numerical simulation and by laser-Doppler velocimetry for an annulus of aspect ratio GAMMA = 1.05 with a radius ratio eta = 0.5066. Stationary states and relaxation towards them were explored close to the transition from the primary flow, which is mirror symmetric with respect to the midplane of the annulus, to a flow which gradually loses the symmetry. Detailed comparison of numerically simulated and measured velocity fields is made.

  17. Radius ratio effects on natural heat transfer in concentric annulus

    DEFF Research Database (Denmark)

    Alipour, M.; Hosseini, R.; Kolaei, Alireza Rezania

    2013-01-01

    This paper studies natural convection heat transfer in vertical and electrically heated annulus. The metallic cylinders mounted concentrically in a parallel tube. Measurements are carried out for four input electric powers and three radius ratios with an apparatus immersed in stagnant air...

  18. Flow of viscoplastic fluids in a rotating concentric annulus

    DEFF Research Database (Denmark)

    Hassager, Ole; Bittleston, Simon H.

    1992-01-01

    A difficulty in any flow calculation with viscoplastic fluids such as Bingham fluids is the determination of possible plug zones in which no deformation occurs. This paper investigates the flow in a concentric annulus when there is both an axial and tangential flow, the tangent flow arising from ...

  19. Reproducibility of aortic annulus measurements by computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Schuhbaeck, Annika; Achenbach, Stephan [University of Erlangen, Department of Cardiology, Erlangen (Germany); University of Giessen, Department of Cardiology, Giessen (Germany); Pflederer, Tobias; Marwan, Mohamed; Schmid, Jasmin; Arnold, Martin [University of Erlangen, Department of Cardiology, Erlangen (Germany); Nef, Holger; Rixe, Johannes; Hecker, Franziska [University of Giessen, Department of Cardiology, Giessen (Germany); Schneider, Christian [University of Giessen, Department of Radiology, Giessen (Germany); Lell, Michael; Uder, Michael [University of Erlangen, Department of Radiology, Erlangen (Germany)

    2014-08-15

    To evaluate a systematic approach for measurement of aortic annulus dimensions by cardiac computed tomography. CT data sets of 64 patients were evaluated. An oblique cross-section aligned with the aortic root was created by systematically identifying the caudal insertion points of the three aortic cusps and sequentially aligning them in a double oblique plane. Aortic annulus dimensions, distances of coronary ostia and a suitable fluoroscopic projection angle were independently determined by two observers. Interobserver intraclass correlation coefficients (ICC) for aortic annulus diameters were excellent (ICC 0.89-0.93). Agreement for prosthesis size selection was excellent (k = 0.86 for mean, k = 0.84 for area-derived and k = 0.91 for circumference-derived diameter). Mean distances of the left/right coronary ostium were 13.4 ± 2.4/14.4 ± 2.8 mm for observer 1 and 13.2 ± 2.7/13.5 ± 3.2 mm for observer 2 (p = 0.30 and p = 0.0001, respectively; ICC 0.76/0.77 for left/right coronary artery). A difference of less than 10 for fluoroscopic projection angle was achieved in 84.3 % of patients. A systematic approach to generate a double oblique imaging plane exactly aligned with the aortic annulus demonstrates high interobserver and intraobserver agreements for derived measurements which are not influenced by aortic root calcification. (orig.)

  20. [Aortic valve replacement for the small aortic annulus].

    Science.gov (United States)

    Oshima, H; Usui, A; Akita, T; Ueda, Y

    2006-04-01

    Aortic valve surgery for the small aortic annulus is still challenging for surgeons. Recently, the new types of high performance prosthesis have been developed and the chance of an aortic root enlargement (ARE) is decreasing. In this study, we propose the ideal strategy of the aortic surgery for the small aortic annulus. We analyzed the clinical records of 158 patients who underwent aortic valve replacement from August 1999 to October 2005 in our institution. The small aortic annulus was observed in 38 patients (24%). Fourteen patients of this group underwent ARE. Patient-prosthesis mismatch (PPM) was less frequently observed in patients with ARE compared to those without ARE. The additional time required for ARE was not considerable, and neither ischemic time nor cardiopulmonary bypass time was significantly prolonged by ARE. In conclusion, we have to select a prosthesis with sufficient orifice area to avoid PPM, otherwise we should choose an option of ARE. For this consideration, we definitely need the chart that demonstrates the relationship between the nominal size of various types of prostheses and the size of a patient's annulus that those prostheses actually fit.

  1. Stability of Unsteady Mixed Convection in a Horizontal Concentric Annulus

    Directory of Open Access Journals (Sweden)

    Kamil Kahveci

    2016-01-01

    Full Text Available In this study, stability of unsteady mixed convection in a horizontal annulus between two concentric cylinders was investigated numerically. The surfaces of the cylinders were considered to be at fixed temperatures and it was assumed that the hot inner cylinder is rotating at a constant angular velocity. The buoyancy forces were formulated utilizing the Boussinesq approximation. The governing equations of fluid flow and heat transfer in the annulus were solved with a finite element method for different values of the geometric (radius ratio and transport parameters (Rayleigh number and Reynolds number. Development of the convective flow and heat transfer was expressed by the average Nusselt number for the outer cylinder. The results show that, for a narrow gap annulus, convective flow induces flow bifurcation and becomes unstable for high values of the Rayleigh number. Flow becomes more unstable with an increase in the Reynolds number. For a wide gap annulus, flow is stable for all values of the Rayleigh number if the rotation effects are small. On the other hand, convective flow becomes unstable for the modest and high values of the Ra number with an increase in the Re number.

  2. Growth of mitral annulus in the pediatric patient after suture annuloplasty of the entire posterior mitral annulus.

    Science.gov (United States)

    Komoda, Takeshi; Huebler, Michael; Berger, Felix; Hetzer, Roland

    2009-08-01

    When mitral annuloplasty is performed in small children, room for annular growth should be allowed. However, it has not been reported how the valve develops after mitral annuloplasty of the entire posterior annulus. We report a case showing traces of annular growth at redo surgery. A female patient suffering from mitral valve insufficiency due to annular dilatation underwent modified Paneth plasty with Kay-Wooler commissural plication annuloplasty at the age of two years one month. In redo surgery 8.4 years after initial repair, enlargement of the commissural portion of the posterior annulus in addition to enlargement of the anterior leaflet and anterior annulus was observed. Modified Paneth plasty reinforced with a pericardial strip and Kay-Wooler annuloplasty of the posteromedial commissure were performed. Mitral orifice size measured with the Hegar dilator was 18 mm after the re-repair, increasing from 16 mm after the initial repair. Taking into account the normal mitral annulus diameter related to body surface area (BSA) of 16 mm at initial operation and 20 mm at redo surgery, the increase in mitral orifice size from 16 mm to 18 mm in this patient may be regarded as the annular growth in 8.4 years.

  3. Nematic Equilibria on a Two-Dimensional Annulus

    KAUST Repository

    Lewis, A. H.

    2017-01-16

    We study planar nematic equilibria on a two-dimensional annulus with strong and weak tangent anchoring, in the Oseen–Frank theoretical framework. We analyze a radially invariant defect-free state and compute analytic stability criteria for this state in terms of the elastic anisotropy, annular aspect ratio, and anchoring strength. In the strong anchoring case, we define and characterize a new spiral-like equilibrium which emerges as the defect-free state loses stability. In the weak anchoring case, we compute stability diagrams that quantify the response of the defect-free state to radial and azimuthal perturbations. We study sector equilibria on sectors of an annulus, including the effects of weak anchoring and elastic anisotropy, giving novel insights into the correlation between preferred numbers of boundary defects and the geometry. We numerically demonstrate that these sector configurations can approximate experimentally observed equilibria with boundary defects.

  4. Formation of the Terrestrial Planets from a Narrow Annulus

    CERN Document Server

    Hansen, Brad

    2009-01-01

    We show that the assembly of the Solar System terrestrial planets can be successfully modelled with all of the mass initially confined to a narrow annulus between 0.7 and 1.0 AU. With this configuration, analogues of Mercury and Mars often form from the collisional evolution of material diffusing out of the annulus under the scattering of the forming Earth and Venus analogues. The final systems also possess eccentricities and inclinations that match the observations, without recourse to dynamical friction from remnant small body populations. Finally, the characteristic assembly timescale for Earth analogues is rapid in this model, and consistent with cosmochemical models based on the $^{182}$Hf--$^{182}$W isotopes. The agreement between this model and the observations suggests that terrestrial planet systems may also be formed in `planet traps', as has been proposed recently for the cores of giant planets in our solar system and others.

  5. A numerical study of natural convection in a narrow annulus

    Energy Technology Data Exchange (ETDEWEB)

    Sahai, V.

    1991-12-01

    Various numerical models were used to predict the natural convection of a solidifying liquid metal in a narrow annulus. Previous work in this area do not consider the temperature variation that exists in the fluid and the resulting heat conduction in the solid mold material. The finite element fluid dynamics code FIDAP was sued to solve these models. The results indicate that the natural convective effects are small. 6 refs.

  6. A numerical study of natural convection in a narrow annulus

    Science.gov (United States)

    Sahai, V.

    1991-12-01

    Various numerical models were used to predict the natural convection of a solidifying liquid metal in a narrow annulus. Previous work in this area does not consider the temperature variation that exists in the fluid and the resulting heat conduction in the solid mold material. The finite element fluid dynamics code FIDAP was used to solve these models. The results indicate that the natural convective effects are small.

  7. Instability of diverging and converging flows in an annulus

    CERN Document Server

    Ilin, Konstantin

    2012-01-01

    The stability of two-dimensional diverging and converging flows in an annulus between two permeable cylinders is examined. The basic flow is irrotational and has both the radial and azimuthal components. It is shown that for a wide range of the parameters of the problem, the basic flow is unstable to small two-dimensional perturbations. The instability is inviscid and oscillatory and persists if the viscosity of the fluid is taken into consideration.

  8. Simple annulus power balance in EBT-I

    Energy Technology Data Exchange (ETDEWEB)

    Borowski, S.K.; Uckan, N.A.; Jaeger, E.F.; Kammash, T.

    1979-09-01

    An essential feature of the ELMO Bumpy Torus (EBT) concept is the presence of a relativistic electron annulus in each of the toroidal mirror sectors. These high beta annuli are formed and sustained by microwave heating and are of sufficient density and temperature that diamagnetic currents produce the necessary minimum in the magnetic field required for MHD stability of the toroidal core plasma. Because electron rings play an important role in confinement characteristics and performance of EBT, the trade-off between the quality of the confinement afforded by the rings and the power required to sustain the rings represents an important problem in a fusion reactor. Theoretical estimates of the microwave power required to sustain the annulus are found to be within a factor of 2 of the experimentally determined value. Scaling projections that are shown for both EBT-I and EBT-S enable one to examine the sensitivity of the annulus electron temperature as a function of core plasma density for various microwave power levels. The results are found to be sensitive to the details of the hot electron distribution function as well as geometric and scaling parameters. Improvements to the model are under way in order to increase its capability and accuracy in assessing the overall power balance.

  9. [Modeling of introgression between Elymus caninus and E. fibrosus (Poaceae) and their registration using one-dimensional SDS electrophoresis].

    Science.gov (United States)

    Gerus, D E; Agafonov, A V

    2006-12-01

    Artificial sexual hybrids between Elymus caninus (L.) L. and E. fibrosus (Schrebk) Tzvel. were experimentally examined in generations F1-F5. The possibility of genetic introgression between these species was shown. Morphologically, the hybrid plants can be assigned to either of the parental species or to variety E. caninus var. muticus (Holmb.) Karlsson. Some traits (spike density, leaf blade width, leaf blade pubescence, awns of lemmas) exhibited considerable variation. Polypeptide spectra of endosperm proteins were characterized in the initial parental biotypes and the hybrid progeny, using a gel-buffer SDS electrophoresis system. It was suggested that successful interspecies hybridization requires backcrosses or normalizing crosses. The possibility of sexual genetic exchange enables to utilize the gene pools of the two species to transfer the required traits in selection forage forms.

  10. Project W-320 high vacuum 241-AY-102 annulus ventilation system operability test report

    Energy Technology Data Exchange (ETDEWEB)

    Bailey, J.W.

    1998-03-12

    This report documents the test results of OTP-320-001, Tank 241-AY-102 Annulus Ventilation System Testing. Included in the appendices are: (1) Supporting documentation prepared to demonstrate the structural integrity of the tank at high annulus vacuum (<20 INWG), and (2) a report that identifies potential cross connections between the primary and annulus ventilation systems. These cross connections were verified to be eliminated prior to the start of testing.

  11. A technique of aortic annulus enlargement with a Freestyle stentless bioprosthesis.

    Science.gov (United States)

    Bical, Olivier M; Nutu, Ovidiu; Deleuze, Philippe

    2012-02-01

    We describe our surgical technique to manage a small aortic annulus during aortic valve replacement. Starting with the posterior annular enlargement incision described by Manouguian, a stentless porcine aortic root, with excision of the left and right porcine coronary segments and conservation of the mural wall (Freestyle MS design, Medtronic, Minneapolis, MN ), was used. The Freestyle bioprosthesis enlarges the aortic annulus using a direct suture of the valve on the enlarged annulus, and the aorta is closed by a direct suture of the mural wall of the bioprosthesis. Therefore, the aortic annulus enlargement is made only using the aortic bioprosthesis, without other material.

  12. Numerical analysis of laminar forced convection in a spherical annulus

    Energy Technology Data Exchange (ETDEWEB)

    Tuft, D.B.

    1980-07-21

    Calculations of steady laminar incompressible fluid-flow and heat transfer in a spherical annulus are presented. Steady pressures, temperatures, velocities, and heat transfer coefficients are calculated for an insulated outer sphere and a 0/sup 0/C isothermal inner sphere with 50/sup 0/C heated water flowing in the annulus. The inner sphere radius is 13.97 cm, the outer sphere radius is 16.83 cm and the radius ratio is 1.2. The transient axisymmetric equations of heat, mass, and momentum conservation are solved numerically in spherical coordinates. The transient solution is carried out in time until steady state is achieved. A variable mesh is used to improve resolution near the inner sphere where temperature and velocity gradients are steep. It is believed that this is the first fully two-dimensional analysis of forced flow in a spherical annulus. Local and bulk Nusselt numbers are presented for Reynolds numbers from 4.4 to 440. Computed bulk Nusselt numbers ranged from 2 to 50 and are compared to experimental results from the literature. Inlet flow jetting off the inner sphere and flow separation are predicted by the analysis. The location of wall jet separation was found to be a function of Reynolds number, indicating the location of separation depends upon the ratio of inertia to viscous forces. Wall jet separation has a pronounced effect on the distribution of local heat flux. The area between inlet and separation was found to be the most significant area for heat transfer. Radial distributions of azimuthal velocity and temperature are presented for various angles beginning at the inlet. Inner sphere pressure distribution is presented and the effect on flow separation is discussed.

  13. Magnetorotational Instability in a Rotating Liquid Metal Annulus

    Energy Technology Data Exchange (ETDEWEB)

    Hantao Ji; Jeremy Goodman; Akira Kageyama

    2001-03-10

    Although the magnetorotational instability (MRI) has been widely accepted as a powerful accretion mechanism in magnetized accretion disks, it has not been realized in the laboratory. The possibility of studying MRI in a rotating liquid-metal annulus (Couette flow) is explored by local and global stability analysis and magnetohydrodynamic (MHD) simulations. Stability diagrams are drawn in dimensionless parameters, and also in terms of the angular velocities at the inner and outer cylinders. It is shown that MRI can be triggered in a moderately rapidly rotating table-top apparatus, using easy-to-handle metals such as gallium. Practical issues of this proposed experiment are discussed.

  14. Nucleate boiling pressure drop in an annulus: Book 5

    Energy Technology Data Exchange (ETDEWEB)

    1992-11-01

    The application of the work described in this report is the production reactors at the Savannah River Site, and the context is nuclear reactor safety. The Loss of Coolant Accident (LOCA) scenario considered involves a double-ended break of a primary coolant pipe in the reactor. During a LOCA, the flow through portions of the reactor may reverse direction or be greatly reduced, depending upon the location of the break. The reduced flow rate of coolant (D{sub 2}O) through the fuel assembly channels of the reactor -- downflow in this situation -- can lead to boiling and to the potential for flow instabilities which may cause some of the fuel assembly channels to overheat and melt. That situation is to be avoided. The experimental approach is to provide a test annulus which simulates geometry, materials, and flow conditions in a Mark-22 fuel assembly (Coolant Channel 3) to the extent possible. The key analysis approaches are: To compare the minima in the measured demand curves with analytical criteria, in particular the Saha-Zuber (1974) model; and to compare the pressure and temperature as a function of length in the annulus with an integral model for flow boiling in a heated channel. Nineteen test series and a total of 178 tests were performed. Testing addressed the effects of: Heat flux; pressure; helium gas; power tilt; ribs; asymmetric heat flux. This document consists solely of the plato file index from 11/87 to 11/90.

  15. Ultrasonic defect detection and size approximation using thin annulus probes

    Energy Technology Data Exchange (ETDEWEB)

    Light, G.M.; Fisher, J.L.; Tennis, R.F.; Stolte, J.S.; Hendrix, G.J. [Southwest Research Inst., San Antonio, TX (United States)

    1994-12-31

    Concern has been generated recently about the capabilities of performing nondestructive evaluation (NDE) of the closure head penetrations in nuclear-reactor pressure vessels (PV). These penetrations, primarily for instrumentation and control rod drive mechanisms (CRDMs), are usually thick-walled Inconel tubes, shrink-fitted into the steel closure head. The penetrations are then welded between the outside surface of the penetration and inside surface of the closure head. Stress corrosion cracks initiating at the inner surface of the penetration have been reported at several plants. Through wall cracks in the CRDM penetration or CRDM weld could lead to loss of PV coolant. The penetration presents a complex geometry for conventional NDE techniques. A thermal sleeve, through which pass the mechanical linkages for control-rod operation, is inserted into the penetration so that only a small annulus (nominally 3 mm) exists between the thermal sleeve and inside surface of the penetration. SwRI has developed and evaluated ultrasonic techniques for sizing defects in this area. Long, thin probes were designed to fit into the annulus to carry irrigated ultrasonic transducers into the region of interest. The probes were used to detect cracks in the penetration and to estimate remaining wall thickness.

  16. Dufour and Soret Effects on Square Porous Annulus

    Directory of Open Access Journals (Sweden)

    N. Nik-Ghazali

    2014-04-01

    Full Text Available A study on heat and mass transfer behaviour on porous medium embedded in a square annulus is conducted. The inner surface wall is considered to have a cool temperature Tc while the outer surface is exposed to a hot temperature Th. Finite element method (FEM is used to solve the governing partial differential equations. The results present the influences of the Dufour and Soret effects on the heat and mass transfer of a square annulus. The effects of various physical parameters on the temperature and concentration profiles together with the local Nusselt and Sherwood numbers are presented graphically. It is found that when Dufour parameter is increased, Nusselt number increases. Dufour effect has more influences on velocity profile, while it has no significant effect on the concentration and can be deemed negligible. It is observed that the local Nusselt number is highest at the bottom wall for low values of Dufour parameter; however, the top wall Nusselt number is highest for higher values of Dufour parameter. Soret effect tends to make more significant contribution to the concentration profile than Dufour effect.

  17. Screening of hyaluronic acid-poly(ethylene glycol) composite hydrogels to support intervertebral disc cell biosynthesis using artificial neural network analysis.

    Science.gov (United States)

    Jeong, Claire G; Francisco, Aubrey T; Niu, Zhenbin; Mancino, Robert L; Craig, Stephen L; Setton, Lori A

    2014-08-01

    Hyaluronic acid (HA)-poly(ethylene glycol) (PEG) composite hydrogels have been widely studied for both cell delivery and soft tissue regeneration applications. A very broad range of physical and biological properties have been engineered into HA-PEG hydrogels that may differentially affect cellular "outcomes" of survival, synthesis and metabolism. The objective of this study was to rapidly screen multiple HA-PEG composite hydrogel formulations for an effect on matrix synthesis and behaviors of nucleus pulposus (NP) and annulus fibrosus (AF) cells of the intervertebral disc (IVD). A secondary objective was to apply artificial neural network analysis to identify relationships between HA-PEG composite hydrogel formulation parameters and biological outcome measures for each cell type of the IVD. Eight different hydrogels were developed from preparations of thiolated HA (HA-SH) and PEG vinylsulfone (PEG-VS) macromers, and used as substrates for NP and AF cell culture in vitro. Hydrogel mechanical properties ranged from 70 to 489kPa depending on HA molecular weight, and measures of matrix synthesis, metabolite consumption and production and cell morphology were obtained to study relationships to hydrogel parameters. Results showed that NP and AF cell numbers were highest upon the HA-PEG hydrogels formed from the lower-molecular-weight HA, with evidence of higher sulfated glycosaminoglycan production also upon lower-HA-molecular-weight composite gels. All cells formed more multi-cell clusters upon any HA-PEG composite hydrogel as compared to gelatin substrates. Formulations were clustered into neurons based largely on their HA molecular weight, with few effects of PEG molecular weight observed on any measured parameters. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  18. Aortic valve replacement with the Nicks annulus enlargement procedure 12 years after mitral valve replacement.

    Science.gov (United States)

    Kazama, S; Kurata, A; Yamashita, Y

    1999-10-01

    An aortic valve replacement was successfully performed employing the Nicks annulus enlargement procedure in a case of aortic valve stenosis with small annulus 12 years after mitral valve replacement. Previous mitral valve replacement does not preclude feasibility of the Nicks procedure.

  19. Design and analysis of annulus core few mode EDFA for modal gain equalization

    CERN Document Server

    Gaur, Ankita

    2016-01-01

    Few-mode fiber amplifier is widely under study to overcome the issue of internet traffic in optical communication. This article proposes annulus core few-mode erbium doped fiber (FM-EDF) with annulus or extra annulus doping for amplification of the LP01, LP11, LP21, and LP31 signal mode groups with low differential modal gain (DMG). Our simulations confirm that extra annulus doping helps in reducing DMG of higher order mode groups. We have achieved less than 2.2 dB DMG over C-band for 4-mode groups using extra annulus doping. The proposed EDF would be useful for space division multiplexing (SDM) based optical fiber communication system.

  20. Design and Analysis of Annulus Core Few Mode EDFA for Modal Gain Equalization

    Science.gov (United States)

    Gaur, Ankita; Rastogi, Vipul

    2016-05-01

    Few-mode fiber amplifier is widely under study to overcome the issue of internet traffic in optical communication. This article proposes annulus core few-mode erbium doped fiber (FM-EDF) with annulus or extra annulus doping for amplification of the LP01, LP11, LP21, and LP31 signal mode groups with low differential modal gain (DMG). Our simulations confirm that extra annulus doping helps in reducing DMG of higher order mode groups. We have achieved less than 2.2 dB DMG over C-band for 4-mode groups using extra annulus doping. The proposed EDF would be useful for space division multiplexing (SDM) based optical fiber communication system.

  1. In vivo dynamic deformation of the mitral valve annulus.

    Science.gov (United States)

    Eckert, Chad E; Zubiate, Brett; Vergnat, Mathieu; Gorman, Joseph H; Gorman, Robert C; Sacks, Michael S

    2009-09-01

    Though mitral valve (MV) repair surgical procedures have increased in the United States [Gammie, J. S., et al. Ann. Thorac. Surg. 87(5):1431-1437, 2009; Nowicki, E. R., et al. Am. Heart J. 145(6):1058-1062, 2003], studies suggest that altering MV stress states may have an effect on tissue homeostasis, which could impact the long-term outcome [Accola, K. D., et al. Ann. Thorac. Surg. 79(4):1276-1283, 2005; Fasol, R., et al. Ann. Thorac. Surg. 77(6):1985-1988, 2004; Flameng, W., P. Herijgers, and K. Bogaerts. Circulation 107(12):1609-1613, 2003; Gillinov, A. M., et al. Ann. Thorac. Surg. 69(3):717-721, 2000]. Improved computational modeling that incorporates structural and geometrical data as well as cellular components has the potential to predict such changes; however, the absence of important boundary condition information limits current efforts. In this study, novel high definition in vivo annular kinematic data collected from surgically implanted sonocrystals in sheep was fit to a contiguous 3D spline based on quintic-order hermite shape functions with C(2) continuity. From the interpolated displacements, the annular axial strain and strain rate, bending, and twist along the entire annulus were calculated over the cardiac cycle. Axial strain was shown to be regionally and temporally variant with minimum and maximum values of -10 and 4%, respectively, observed. Similarly, regionally and temporally variant strain rate values, up to 100%/s contraction and 120%/s elongation, were observed. Both annular bend and twist data showed little deviation from unity with limited regional variations, indicating that most of the energy for deformation was associated with annular axial strain. The regionally and temporally variant strain/strain rate behavior of the annulus are related to the varied fibrous-muscle structure and contractile behavior of the annulus and surrounding ventricular structures, although specific details are still unavailable. With the high resolution

  2. Dispersion phenomena in helical flow in a concentric annulus.

    Science.gov (United States)

    Song, Young Seok; Brenner, Howard

    2009-12-14

    We examined dispersion phenomena of solutes in helical flow in a concentric annulus through a multiscale approach. The helical flow was developed by the combination of the Poiseuille flow and Couette flow. Here, we present an analytic model that can address the multidimensional Taylor dispersion in the helical flow under a lateral field of thermophoresis (or thermal diffusion) in the gapwise direction. Macroscopic parameters including the average solute velocity and dispersivity were analyzed using relevant microscopic physicochemical properties. The mathematically obtained results were validated by the numerical simulation carried out in this study. The findings show that macrotransport processes are robust and straightforward to handle multidimensional dispersion phenomena of solutes in helical flow. This study is expected to provide a theoretical platform for applications of helical flow such as tube exchangers, oil drilling, and multidimensional field flow fractionations (e.g., helical flow field flow fractionation).

  3. Opposing flow in square porous annulus: Influence of Dufour effect

    Science.gov (United States)

    Athani, Abdulgaphur; Al-Rashed, Abdullah A. A. A.; Khaleed, H. M. T.

    2016-06-01

    Heat and mass transfer in porous medium is very important area of research which is also termed as double diffusive convection or thermo-solutal convection. The buoyancy ratio which is the ratio of thermal to concentration buoyancy can have negative values thus leading to opposing flow. This article is aimed to study the influence of Dufour effect on the opposing flow in a square porous annulus. The partial differential equations that govern the heat and mass transfer behavior inside porous medium are solved using finite element method. A three node triangular element is used to divide the porous domain into smaller elements. Results are presented with respect to geometric and physical parameters such as duct diameter ratio, Rayleigh number, radiation parameter etc. It is found that the heat transfer increase with increase in Rayleigh number and radiation parameter. It is observed that Dufour coefficient has more influence on velocity profile.

  4. On the flow in an annulus surrounding a whirling cylinder

    Science.gov (United States)

    Brennen, C.

    1976-01-01

    When fluid in an annulus between two cylinders is set in motion by whirling movements of one or both of the cylinders, dynamic forces are imposed by the fluid on the cylinders. Knowledge of these forces is frequently important, indeed often critical, to the engineer designing rotor systems or journal bearings. Quite general solutions of the Navier-Stokes equations are presented for this problem and are limited only by restrictions on the amplitude of the whirl motion. From these solutions, the forces are derived under a wide variety of circumstances, including large and small annular widths, high and low Reynolds numbers, and the presence and absence of a mean flow created by additional net rotation of one or both of the cylinders.

  5. HEAT TRANSFER ENHANCEMENT AND PRESSURE DROP OF GROOVED ANNULUS OF DOUBLE PIPE HEAT EXCHANGER

    Directory of Open Access Journals (Sweden)

    Putu Wijaya Sunu

    2017-05-01

    Full Text Available This investigation was performed to experimentally investigate the enhancement of heat transfer and the friction of an annulus in a double pipe heat exchanger system with rectangular grooves in the turbulent flow regime. The shell is made of acrylic and its diameter is 28 mm. The tube is made of aluminium and its diameter is 20 mm. Grooves were incised in the annulus room with a circumferential pattern, with a groove space of 2 mm, a distance between the grooves of 8mm and a groove height of 0.3 mm. The experiments consist of temperature and pressure measurement and a flow visualization. Throughout the investigation, the cold fluid flowed in the annulus room. The Reynold number of cold fluid varied from about 31981 to 43601 in a counter flow condition. The volume flow rate of hot fluid remains constant with Reynold number about 30904. Result showed the effect of grooves, which are applied in the annulus room. The grooves induce the pressure drop, the pressure drop in the grooved annulus was greater by about 15.88% to 16.72% than the one in the smooth annulus. The total heat transfer enhancement is of 1.09–1.11. Moreover, the use of grooves in the annulus of the heat exchanger not only increase the heat transfer process, but also increase the pressure drop, which is related to the friction factor.

  6. Application of Regent mechanical valve in patients with small aortic annulus: 3-year follow-up

    OpenAIRE

    Zhao Dong; Wang Chunsheng; Hong Tao; Pan Cuizhen; Guo Changfa

    2012-01-01

    Abstract Background Aortic valve replacement (AVR) with a small aortic annulus is always challenging for the cardiac surgeon. In this study, we sought to evaluate the midterm performance of implantation with a 17-mm or 19-mm St. Jude Medical Regent (SJM Regent) mechanical valve in retrospective consecutive cohort of patients with small aortic annulus (diameter ≤ 19 mm). Methods From January 2008 to April 2011, 40 patients (31 female, mean age = 47.2 ± 5.8 years) with small aortic annulus (≤19...

  7. Minimizing cryopreservation-induced loss of disc cell activity for storage of whole intervertebral discs

    Directory of Open Access Journals (Sweden)

    SCW Chan

    2010-06-01

    Full Text Available Severe intervertebral disc (IVD degeneration often requires disc excision and spinal fusion, which leads to loss of spinal segment mobility. Implantation of an allograft disc or tissue engineered disc construct emerges as an alternative to artificial disc replacement for preserving the motion of the degenerated level. Establishment of a bank of cadaveric or engineered cryopreserved discs enables size matching, and facilitates clinical management. However, there is a lack of understanding of the behaviour of disc cells during cryopreservation, as well as how to maximize their survival, such that disc graft properties can be preserved. Here, we report on the effect of alterations in cooling rates, cryoprotective agents (CPAs, and duration of pre-cryopreservation incubation in CPA on cellular activity in whole porcine lumbar discs. Our results indicated that cooling rates of -0.3°C/min and -0.5°C /min resulted in the least loss of metabolic activity in nucleus pulposus (NP and annulus fibrosus (AF respectively, while metabolic activity is best maintained by using a combination of 10% dimethylsulphoxide (DMSO and 10% propylene-glycol (PG as CPA. By the use of such parameters, metabolic activity of the NP and the AF cells could be maintained at 70% and 45%, respectively, of that of the fresh tissue. Mechanical testing and histological evaluation showed no significant differences in mechanical properties or alterations in disc structure compared to fresh discs. Despite the limitations of the animal model, our findings provide a framework for establishing an applicable cryopreservation protocol for human disc allografts or tissue-engineered disc constructs.

  8. Region specific response of intervertebral disc cells to complex dynamic loading: an organ culture study using a dynamic torsion-compression bioreactor.

    Directory of Open Access Journals (Sweden)

    Samantha C W Chan

    Full Text Available The spine is routinely subjected to repetitive complex loading consisting of axial compression, torsion, flexion and extension. Mechanical loading is one of the important causes of spinal diseases, including disc herniation and disc degeneration. It is known that static and dynamic compression can lead to progressive disc degeneration, but little is known about the mechanobiology of the disc subjected to combined dynamic compression and torsion. Therefore, the purpose of this study was to compare the mechanobiology of the intervertebral disc when subjected to combined dynamic compression and axial torsion or pure dynamic compression or axial torsion using organ culture. We applied four different loading modalities [1. control: no loading (NL, 2. cyclic compression (CC, 3. cyclic torsion (CT, and 4. combined cyclic compression and torsion (CCT] on bovine caudal disc explants using our custom made dynamic loading bioreactor for disc organ culture. Loads were applied for 8 h/day and continued for 14 days, all at a physiological magnitude and frequency. Our results provided strong evidence that complex loading induced a stronger degree of disc degeneration compared to one degree of freedom loading. In the CCT group, less than 10% nucleus pulposus (NP cells survived the 14 days of loading, while cell viabilities were maintained above 70% in the NP of all the other three groups and in the annulus fibrosus (AF of all the groups. Gene expression analysis revealed a strong up-regulation in matrix genes and matrix remodeling genes in the AF of the CCT group. Cell apoptotic activity and glycosaminoglycan content were also quantified but there were no statistically significant differences found. Cell morphology in the NP of the CCT was changed, as shown by histological evaluation. Our results stress the importance of complex loading on the initiation and progression of disc degeneration.

  9. analysis of flow in a concentric annulus using finite element method

    African Journals Online (AJOL)

    user

    ABSTRACT. This work presents the computational modelling of the velocity distribution of an incompressible fluid flowing in a ... concentric annulus with center body rotation. [9] used .... pipe at a glance with a very high accuracy compared to.

  10. The Cyclicity of the Period Annulus Around the Quadratic Isochronous Center

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The number of the limit cycles bifurcating in small quadratic perturbations of quadratic systems with an isochronous center is studied, it turns out that the cyclicity of the period annulus around one kind of quadratic isochronous center is two.

  11. Annulus electromagnetic stirring for preparing semisolid A357 aluminum alloy slurry

    Institute of Scientific and Technical Information of China (English)

    BAI Yue-long; XU Jun; ZHANG Zhi-feng; SHI Li-kai

    2009-01-01

    The effects of pouring temperature and annulus gap width on the microstructure of the semi-solid A357 aluminum alloy slurry prepared by annulus electromagnetic stirring(AEMS) technology were investigated. The results show that low pouring temperature and narrow annulus gap are advantageous to obtaining the small spherical primary α(Al) phase. The lower the pouring temperature is and the smaller the annulus gap width is, the more uniform, the smaller and the more spherical the microstructure is. The microstructures obtained by the ordinary electromagnetic stirring and AEMS were compared. The results indicate that the primary α(Al) particles are globular, small and distribute homogeneously in the slurry obtained by AEMS. But in the slurry obtained by the ordinary electromagnetic stirring, the primary α(Al) particles are small dendrites in the edge of the slurry and they are large and rosette-like or dendritic in the inner of the slurry.

  12. Aortic valve replacement with concomitant annular enlargement for small aortic annulus of less than 19 mm.

    Science.gov (United States)

    Takakura, H; Sasaki, T; Hashimoto, K; Hachiya, T; Onoguchi, K; Oshiumi, M; Takeuchi, S

    2000-06-01

    Three female patients with aortic stenosis associated with a severely small annulus underwent aortic valve replacement. In intraoperative measurements, a 19-mm obtulator could not pass through the aortic annulus in each case. We therefore concluded that it would be difficult to implant an appropriate-sized prosthesis in a routine fashion, so we performed an annular enlargement in a modified Nicks procedure. By using a wide teardrop-shaped patch for enlargement and slightly tilting insertion of a prosthesis, a 21 mm bileaflet mechanical prosthesis could be inserted into the enlarged annulus. Despite being a simpler method than other enlarging procedures, a two- or three-sizes larger prosthesis than the native annulus can be inserted with relative ease. Thus, the use of a 19 mm mechanical prosthesis may be avoidable in most adult cases.

  13. Some exploratory experiments with a new type of rotating, differentially-heated fluid annulus

    OpenAIRE

    Davies, Peter A; Walin, Gösta

    2011-01-01

    Some experiments with a rotating differentially heated annulus are presented. It is demonstrated that with suitable construction of the annulus the strength of the zonal baroclinic motion may be chosen independently of the basic density stratification. In the experiment reported it was found that baroclinic instability occurred in a state characterized by small isotherm slopes. Certain aspects of the observed flow and temperature fields—in particular the basic stratification and the slope of ...

  14. Assessment of the frequency of sperm annulus defects in a large cohort of patients presenting asthenozoospermia

    OpenAIRE

    Dirami, Thassadite; Rode, Baptiste; Wolf, Jean-Philippe; Gacon, Gérard; Dulioust, Emmanuel; Touré, Aminata

    2015-01-01

    International audience; Background: The annulus is a ring-shaped structure located beneath the plasma membrane that connects the midpiece and the principal piece of mammalian sperm flagellum. It has been suggested that the annulus acts as a morphological organizer, guiding flagellum assembly during spermiogenesis, and as a diffusion barrier, confining proteins to distinct compartments of the flagellum in mature sperm. Previous studies on small cohorts of patients have attempted to correlate a...

  15. Loewner Theory in annulus I: evolution families and differential equations

    CERN Document Server

    Contreras, Manuel D; Gumenyuk, Pavel

    2010-01-01

    Loewner Theory, based on dynamical viewpoint, is a powerful tool in Complex Analysis, which plays a crucial role in such important achievements as the proof of famous Bieberbach's conjecture and well-celebrated Schramm's Stochastic Loewner Evolution (SLE). Recently Bracci et al [Bracci et al, to appear in J. Reine Angew. Math. Available on ArXiv 0807.1594; Bracci et al, Math. Ann. 344(2009), 947--962; Contreras et al, Revista Matematica Iberoamericana 26(2010), 975--1012] have proposed a new approach bringing together all the variants of the (deterministic) Loewner Evolution in a simply connected reference domain. We construct an analogue of this theory for the annulus. In this paper, the first of two articles, we introduce a general notion of an evolution family over a system of annuli and prove that there is a 1-to-1 correspondence between such families and semicomplete weak holomorphic vector fields. Moreover, in the non-degenerate case, we establish a constructive characterization of these vector fields a...

  16. Thermoconvective vortices in a cylindrical annulus with varying inner radius.

    Science.gov (United States)

    Castaño, D; Navarro, M C; Herrero, H

    2014-12-01

    This paper shows the influence of the inner radius on the stability and intensity of vertical vortices, qualitatively similar to dust devils and cyclones, generated in a cylindrical annulus non-homogeneously heated from below. Little relation is found between the intensity of the vortex and the magnitude of the inner radius. Strong stable vortices can be found for both small and large values of the inner radius. The Rankine combined vortex structure, that characterizes the tangential velocity in dust devils, is clearly observed when small values of the inner radius and large values of the ratio between the horizontal and vertical temperature differences are considered. A contraction on the radius of maximum azimuthal velocity is observed when the vortex is intensified by thermal mechanisms. This radius becomes then nearly stationary when frictional force balances the radial inflow generated by the pressure drop in the center, despite the vortex keeps intensifying. These results connect with the behavior of the radius of the maximum tangential wind associated with a hurricane.

  17. Quantification of aortic annulus in computed tomography angiography: Validation of a fully automatic methodology.

    Science.gov (United States)

    Gao, Xinpei; Boccalini, Sara; Kitslaar, Pieter H; Budde, Ricardo P J; Attrach, Mohamed; Tu, Shengxian; de Graaf, Michiel A; Ondrus, Tomas; Penicka, Martin; Scholte, Arthur J H A; Lelieveldt, Boudewijn P F; Dijkstra, Jouke; Reiber, Johan H C

    2017-08-01

    Automatic accurate measuring of the aortic annulus and determination of the optimal angulation of X-ray projection are important for the trans-catheter aortic valve replacement (TAVR) procedure. The objective of this study was to present a novel fully automatic methodology for the quantification of the aortic annulus in computed tomography angiography (CTA) images. CTA datasets of 26 patients were analyzed retrospectively with the proposed methodology, which consists of a knowledge-based segmentation of the aortic root and detection of the orientation and size of the aortic annulus. The accuracy of the methodology was determined by comparing the automatically derived results with the reference standard obtained by semi-automatic delineation of the aortic root and manual definition of the annulus plane. The difference between the automatic annulus diameter and the reference standard by observer 1 was 0.2±1.0mm, with an inter-observer variability of 1.2±0.6mm. The Pearson correlation coefficient for the diameter was good (0.92 for observer 1). For the first time, a fully automatic tool to assess the optimal projection curves was presented and validated. The mean difference between the optimal projection curves calculated based on the automatically defined annulus plane and the reference standard was 6.4° in the cranial/caudal (CRA/CAU) direction. The mean computation time was short with around 60s per dataset. The new fully automatic and fast methodology described in this manuscript not only provided precise measurements about the aortic annulus size with results comparable to experienced observers, but also predicted optimal X-ray projection curves from CTA images. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Simultaneous PIV and thermography measurements of partially blocked flow in a differentially heated rotating annulus

    Energy Technology Data Exchange (ETDEWEB)

    Harlander, Uwe; Alexandrov, Kiril; Wang, Yongtai; Egbers, Christoph [Brandenburg University of Technology Cottbus, Department of Aerodynamics and Fluid Mechanics, Cottbus (Germany); Wenzel, Julia [University of Leipzig, Institute of Meteorology, Leipzig (Germany)

    2012-04-15

    A radial barrier has been mounted in a differentially heated rotating annulus that partially blocks the azimuthal flow component. The experiment can be seen as an analog to geophysical flows with constrictions, e.g., the Antarctic Circumpolar Current. However, the experiment has been carried out without a particular natural flow in mind. The main interest was to observe a baroclinic annulus flow that does not become saturated. Hence, in contrast to the annulus flow without a barrier, the partially blocked flow remains transient and surface heat fluxes associated with baroclinic life cycles can be studied. The annulus can be subdivided into the upstream half of the barrier, where waves amplify, and the downstream half of the barrier, where waves decay. In the upstream half, the azimuthal mean flow is moderate but with a significant positive eddy radial heat flux. In the downstream half, we find a strong jet in the mean azimuthal flow and furthermore an increased radial mean temperature gradient. The latter points to a weakened or even reversed radial eddy heat flux in the lee side of the barrier. Temperature anomalies appear as large bulges in the outer part of the annulus. Moreover, an outward shift of vortex centers can be observed with respect to centers of temperature anomalies. This phase shift between pressure and temperature anomalies differs from that of classical Eady modes of baroclinic instability. (orig.)

  19. Study on Flow Characteristic of Non-Newtonian fluid in Eccentric Annulus

    Directory of Open Access Journals (Sweden)

    Li Mingzhong

    2013-08-01

    Full Text Available This study studied the flow characteristic of non-newtonian in eccentric annulus of highly-deviated well. On the basis of dimensionless analysis of motion equations and continuity equation, Hele-Shaw model suitable for fluid flow in the annulus was derived. Combined with H-B rheological model, velocity and stream distribution model were founded and calculated by numerical method. Furthermore, two-dimensional flow characteristic in eccentric annulus was got and the influence of different factors (such as yield stress, pressure gradient or eccentricity on velocity distribution in condition of laminar flow was analyzed. Width of flow core in the annular is proportional to yield stress and inversely proportional to pressure gradient. In eccentric annulus, eccentricity influences the stream distribution remarkably: with the increment of eccentricity, the contour lines of stream function gradually centralize in the widest annular gap, however distribute the most loosely in the narrowest annular gap. Axial velocity is the largest in the widest gap. The larger eccentricity is, the larger contrast of axial velocity between in the widest gap and in the narrowest gap is. There is the largest azimuthal velocity in an annular gap of a certain azimuthal angle, however which equals to zero in the widest and narrowest annular gap separately. The larger eccentricity is, the more homogeneous azimuthal velocity is. The velocity contrast in the entire annulus can be smoothed by increasing pressure gradient, power law index or decreasing yield stress.

  20. Aortic Valve Leaflet Replacement with Bovine Pericardium to Preserve Native Dynamic Capabilities of the Aortic Annulus

    Science.gov (United States)

    Kim, Kyung Hwa; Kim, Min Ho; Kim, Won Ho; Lee, Mi Kyung; Lee, Sam Youn

    2014-01-01

    Valve replacement is typically the most appropriate option for treating aortic valve stenotic insufficiency. However, neither mechanical nor bioprosthetic replacement components preserve the circumferential expansion and contraction of a native aortic annulus during the cardiac cycle, because the prosthetic ring is affixed to the annulus. A 64-year-old man presented with a bicuspid and stenotic aortic valve, and the native annulus was too small to accommodate a porcine replacement valve. We fashioned new aortic leaflets from bovine pericardium with use of a template, and we affixed the sinotubular junction with use of inner and outer stabilization rings. Postoperative echocardiograms revealed coaptation of the 3 new leaflets with no regurgitation. At the patient's 5.5-year follow-up examination, echocardiograms showed flexible leaflet movement with a coaptation height of 7 mm, and expansion and contraction of the aortic annulus similar to that of a normal native annulus. The transvalvular pressure gradient was insignificant. If long-term durability of the new leaflets is confirmed, this method of leaflet replacement and fixation of the sinotubular junction might serve as an acceptable alternative to valve replacement in the treatment of aortic valve stenosis. We describe the patient's case and present our methods and observations. PMID:24512414

  1. Aortic valve leaflet replacement with bovine pericardium to preserve native dynamic capabilities of the aortic annulus.

    Science.gov (United States)

    Kim, Kyung Hwa; Choi, Jong Bum; Kim, Min Ho; Kim, Won Ho; Lee, Mi Kyung; Lee, Sam Youn

    2014-02-01

    Valve replacement is typically the most appropriate option for treating aortic valve stenotic insufficiency. However, neither mechanical nor bioprosthetic replacement components preserve the circumferential expansion and contraction of a native aortic annulus during the cardiac cycle, because the prosthetic ring is affixed to the annulus. A 64-year-old man presented with a bicuspid and stenotic aortic valve, and the native annulus was too small to accommodate a porcine replacement valve. We fashioned new aortic leaflets from bovine pericardium with use of a template, and we affixed the sinotubular junction with use of inner and outer stabilization rings. Postoperative echocardiograms revealed coaptation of the 3 new leaflets with no regurgitation. At the patient's 5.5-year follow-up examination, echocardiograms showed flexible leaflet movement with a coaptation height of 7 mm, and expansion and contraction of the aortic annulus similar to that of a normal native annulus. The transvalvular pressure gradient was insignificant. If long-term durability of the new leaflets is confirmed, this method of leaflet replacement and fixation of the sinotubular junction might serve as an acceptable alternative to valve replacement in the treatment of aortic valve stenosis. We describe the patient's case and present our methods and observations.

  2. Technical Information to Support Double Shell Tank (DST) Emergency Annulus Pumping [SEC 1 and 2

    Energy Technology Data Exchange (ETDEWEB)

    REBERGER, D.W.

    2000-09-14

    This document provides the design calculations for the DST Annulus Emergency Pumping Project. This document also contains essential information relative to DST annulus emergency pumping that may not be found in other documents. This information consists of the following: Index drawing for annulus pumping; References to the Acceptance Test Report, DST Emergency Pumping Guide, Time Deployment study, etc.; Statements of work; and Reference CEIS and RMIS numbers. A Vendor Information document, VI-50121, is not included in this document, but a copy can be obtained by contacting Document Control Services. This document contains various information regarding the Hydrostar pumps, such as the air motor, cylinder size, pump installation and operation manual. It also contains information regarding the Flygt BS2060 submersible pump, such as parts list, pump handling, preventative maintenance, overhaul and repair. In addition, this document also has information on 3-way PM ball valves, electrical skid components and the alternate Gurman-Rupp stainless steel submersible pump.

  3. [Surgical technique of aortic valve replacement for small aortic annulus in elderly patients].

    Science.gov (United States)

    Hata, T; Fujiwara, K; Furukawa, H; Tsushima, Y; Yoshitaka, H; Kuinose, M; Minami, H; Ishida, A; Tamura, K; Totsugawa, T; Kanemitsu, H; Ozawa, M

    2006-04-01

    Recent reports have shown that aortic valve replacement in elderly patients over 65 years with atherosclerotic aortic stenosis and a small aortic annulus is possible by using a small sized bioprosthesis (Carpentier-Edwards pericardial valve). Here we present out surgical technique. Firstly, the native calcified aortic valve was removed completely to gain total exposure of the surrounding aortic root and sinus of Valsalva like Bentall procedure. Secondly, a small sized bioprosthesis was implanted with intermittent noneverting mattress 2-0 sutures with spaghetti and small polytetrafluoroethylene (PTFE) felt. Aortic annulus is the dilated by inserting Hegar dilator sizing from 25 to 27 mm. Therefore, aortic valve replacement for small aortic annulus in intra- or supra-annular position should be easily accomplished. Good surgical results and hemodynamic state were achieved in 25 consecutive cases using this technique.

  4. Flow resistance characteristics of water in narrow annulus during heat exchange

    Institute of Scientific and Technical Information of China (English)

    SUN Li-cheng; YAN Chang-qi; SUN Zhong-ning; ZHANG Qing-hua

    2003-01-01

    Considering the special resistance characteristics of fluids flowing through ducts with small gaps, experiments are performed to investigate the resistance characteristics of single-phase water, which is forced to flow through vertical annuli. The gap sizes are 0.9, 1.4 and 2.4mm, respectively. The experiments are conducted under condition of 1atm. The water in the annuli is heated by high temperature water reversely flowing through the inner tube and the outer annulus. The results show that the flow pattern begin to change from laminar to turbulent before Reynolds number approaches 2000, the flow resistance in annulus has little relations with the temperature difference and ways of being heated, but mainly depends on the ratio of mass flux to the width of annulus.

  5. Regimes of Axisymmetric Flow and Scaling Laws in a Rotating Annulus with Local Convective Forcing

    Directory of Open Access Journals (Sweden)

    Susie Wright

    2017-07-01

    Full Text Available We present a numerical study of axisymmetric flow in a rotating annulus in which local thermal forcing, via a heated annular ring on the outside of the base and a cooled circular disk in the centre of the top surface, drives convection. This new configuration is a variant of the classical thermally-driven annulus, where uniform heating and cooling are applied through the outer and inner sidewalls respectively. The annulus provides an analogue to a planetary circulation and the new configuration, with its more relaxed vertical thermal boundary conditions, is expected to better emulate vigorous convection in the tropics and polar regions as well as baroclinic instability in the mid-latitude baroclinic zone. Using the Met Office/Oxford Rotating Annulus Laboratory (MORALS code, we have investigated a series of equilibrated, two dimensional axisymmetric flows across a large region of parameter space. These are characterized in terms of their velocity and temperature fields. When rotation is applied several distinct flow regimes may be identified for different rotation rates and strengths of differential heating. These regimes are defined as a function of the ratio of the horizontal Ekman layer thickness to the non-rotating thermal boundary layer thickness and are found to be similar to those identified in previous annulus experiments. Convection without rotation is also considered and the scaling of the heat transport with Rayleigh number is calculated. This is then compared with existing work on the classical annulus as well as horizontal and Rayleigh-Bénard convection. As with previous studies on both rotating and non-rotating convection the system’s behaviour is found to be aspect ratio dependent. This dependence is seen in the scaling of the non-rotating Nusselt number and in transitions between regimes in the rotating case although further investigation is required to fully explain these observations.

  6. Strain distribution in the intervertebral disc under unconfined compression and tension load by the optimized digital image correlation technique.

    Science.gov (United States)

    Liu, Qing; Wang, Tai-Yong; Yang, Xiu-Ping; Li, Kun; Gao, Li-Lan; Zhang, Chun-Qiu; Guo, Yue-Hong

    2014-05-01

    The unconfined compression and tension experiments of the intervertebral disc were conducted by applying an optimized digital image correlation technique, and the internal strain distribution was analysed for the disc. It was found that the axial strain values of different positions increased obviously with the increase in loads, while inner annulus fibrosus and posterior annulus fibrosus experienced higher axial strains than the outer annulus fibrosus and anterior annulus fibrosus. Deep annulus fibrosus exhibited higher compressive and tensile axial strains than superficial annulus fibrosus for the anterior region, while there was an opposite result for the posterior region. It was noted that all samples demonstrated a nonlinear stress-strain profile in the process of deforming, and an elastic region was shown once the sample was deformed beyond its toe region.

  7. Two-Dimensional Echo-cardiographic Estimation of the Size of the Mitral Valve Annulus

    Directory of Open Access Journals (Sweden)

    Shigenobu,Masaharu

    1982-12-01

    Full Text Available The diameter of the mitral annulus as measured on the long axis by two-dimensional echocardiogram was found to correlate well with the size of the sewing ring used to replace the mitral valve in 35 consecutive patients. The size of the prosthesis which was used could be predicted within 1 mm of error in 83% of the mitral stenosis (MS patients and in 76% of the mitral regurgitation (MR patients in the study. Preoperative echocardiographic estimation of the size of the mitral valve annulus and prediction of the sewing ring size of the prosthetic valve used could reduce the incidence of valve prosthesis-patient mismatch.

  8. Extraordinary acoustic transmission through annuluses in air and its applications in acoustic beam splitter and concentrator

    Energy Technology Data Exchange (ETDEWEB)

    Ge, Yong; Liu, Shu-sen; Yuan, Shou-qi, E-mail: Shouqiy@ujs.edu.cn; Xia, Jian-ping; Guan, Yi-jun [Research Center of Fluid Machinery Engineering and Technology, Jiangsu University, Zhenjiang 212013 (China); Sun, Hong-xiang, E-mail: jsdxshx@ujs.edu.cn [Research Center of Fluid Machinery Engineering and Technology, Jiangsu University, Zhenjiang 212013 (China); Lab of Modern Acoustics, Institute of Acoustics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China); State Key Laboratory of Acoustics, Institute of Acoustics, Chinese Academy of Sciences, Beijing 100190 (China); Zhang, Shu-yi [Lab of Modern Acoustics, Institute of Acoustics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China)

    2016-08-15

    We report an extraordinary acoustic transmission through two layer annuluses made of metal cylinders in air both numerically and experimentally. The effect arises from the enhancement and reconstruction of the incident source induced by different Mie-resonance modes of the annuluses. The proposed system takes advantages of the consistency in the waveform between the input and output waves, the high amplitude amplification of output waves, and the easy adjustment of structure. More interestingly, we investigate the applications of the extraordinary acoustic transmission in the acoustic beam splitter and acoustic concentrator. Our finding should have an impact on ultrasonic applications.

  9. Background Independent Open String Field Theory with Constant B field On the Annulus

    CERN Document Server

    Rashkov, R; Yang, Y

    2001-01-01

    We study Witten's background independent open-string field theory in the presence of a constant B-field at one loop level. The Green's function and the partition function with a constant B-field are evaluated for an annulus.

  10. Aortic annulus and ascending aorta: Comparison of preoperative and periooperative measurement in patients with aortic stenosis

    Energy Technology Data Exchange (ETDEWEB)

    Smid, Michal [Cardiology Department of Internal Medicine, School of Medicine Plzen, Charles University Prague and University Hospital Plzen, alej Svobody 80, 304 60 Plzen (Czech Republic)], E-mail: kosvin@seznam.cz; Ferda, Jiri [Department of Radiology, School of Medicine Plzen, Charles University Prague and University Hospital Plzen, alej Svobody 80, 304 60 Plzen (Czech Republic)], E-mail: ferda@fnplzen.cz; Baxa, Jan [Department of Radiology, School of Medicine Plzen, Charles University Prague and University Hospital Plzen, alej Svobody 80, 304 60 Plzen (Czech Republic)], E-mail: baxaj@fnplzen.cz; Cech, Jakub [Cardiology Department of Internal Medicine, School of Medicine Plzen, Charles University Prague and University Hospital Plzen, alej Svobody 80, 304 60 Plzen (Czech Republic)], E-mail: cechj@fnplzen.cz; Hajek, Tomas [Department of Cardiac Surgery, School of Medicine Plzen, Charles University Prague and University Hospital Plzen, alej Svobody 80, 304 60 Plzen (Czech Republic)], E-mail: hajekt@fnplzen.cz; Kreuzberg, Boris [Department of Radiology, School of Medicine Plzen, Charles University Prague and University Hospital Plzen, alej Svobody 80, 304 60 Plzen (Czech Republic)], E-mail: kreuzberg@fnplzen.cz; Rokyta, Richard [Cardiology Department of Internal Medicine, School of Medicine Plzen, Charles University Prague and University Hospital Plzen, alej Svobody 80, 304 60 Plzen (Czech Republic)], E-mail: rokyta@fnplzen.cz

    2010-04-15

    Background: Precise determination of the aortic annulus size constitutes an integral part of the preoperative evaluation prior to aortic valve replacement. It enables the estimation of the size of prosthesis to be implanted. Knowledge of the size of the ascending aorta is required in the preoperative analysis and monitoring of its dilation enables the precise timing of the operation. Our goal was to compare the precision of measurement of the aortic annulus and ascending aorta using magnetic resonance (MR), multidetector-row computed tomography (MDCT), transthoracic echocardiography (TTE), and transoesophageal echocardiography (TEE) in patients with degenerative aortic stenosis. Methods and results: A total of 15 patients scheduled to have aortic valve replacement were enrolled into this prospective study. TTE was performed in all patients and was supplemented with TEE, CT and MR in the majority of patients. The values obtained were compared with perioperative measurements. For the measurement of aortic annulus, MR was found to be the most precise technique, followed by MDCT, TTE, and TEE. For the measurement of ascending aorta, MR again was found to be the most precise technique, followed by MDCT, TEE, and TTE. Conclusion: In our study, magnetic resonance was found to be the most precise technique for the measurement of aortic annulus and ascending aorta in patients with severe degenerative aortic stenosis.

  11. Surface hydrogenation regulated wrinkling and torque capability of hydrogenated graphene annulus under circular shearing

    Science.gov (United States)

    Li, Yinfeng; Liu, Silin; Datta, Dibakar; Li, Zhonghua

    2015-11-01

    Wrinkles as intrinsic topological feature have been expected to affect the electrical and mechanical properties of atomically thin graphene. Molecular dynamics simulations are adopted to investigate the wrinkling characteristics in hydrogenated graphene annulus under circular shearing at the inner edge. The amplitude of wrinkles induced by in-plane rotation around the inner edge is sensitive to hydrogenation, and increases quadratically with hydrogen coverage. The effect of hydrogenation on mechanical properties is investigated by calculating the torque capability of annular graphene with varying hydrogen coverage and inner radius. Hydrogenation-enhanced wrinkles cause the aggregation of carbon atoms towards the inner edge and contribute to the critical torque strength of annulus. Based on detailed stress distribution contours, a shear-to-tension conversion mechanism is proposed for the contribution of wrinkles on torque capacity. As a result, the graphane annulus anomalously has similar torque capacity to pristine graphene annulus. The competition between hydrogenation caused bond strength deterioration and wrinkling induced local stress state conversion leads to a U-shaped evolution of torque strength relative to the increase of hydrogen coverage from 0 to 100%. Such hydrogenation tailored topological and mechanical characteristics provides an innovative mean to develop novel graphene-based devices.

  12. Structural analysis and evaluation of the 241SY101 tank annulus heat-up

    Energy Technology Data Exchange (ETDEWEB)

    Ziada, H.H.

    1994-10-19

    This document provides the structural analysis (static and thermal loads) of the 241SY101 tank to determine the maximum allowable temperature and rate of heating that could be applied to tank 241SY101 through annulus air heating without detrimental effects to the structural integrity of the concrete and steel liner of the tank.

  13. Three-Dimensional Numerical Simulation of Natural Convection Heat Transfer in an Inclined Cylindrical Annulus

    Institute of Scientific and Technical Information of China (English)

    1996-01-01

    A numerical study of natural convection beat transfer in an inclined cylindrical annulus has been conducted.The inner cylinder of the annulus is maintained at uniform heat flux and the outer cylinder at constant temperature.the two end walls are assumed to be insulated.A numerical code has been developed to calculate the steady state three-dimensional natural convection in an inclined cylindrical annulus,and the research emphasis is placed on the influences of inclination angle α and modified Rayleigh number Ra on the natural convection heat transfer in the annulus.Computations were carried out in the ranges of 0°≤α≤90*,2.5×105≤Ra*≤7and Pr=0.7 with fixed aspect ratio of H=28.97 and radius ratio of K=3.33,The numerical results are compared with the experimental correlations from the literature and the inclination angle effect on heat transfer is found to be insignificant.Detailed results of heat transfer rate,temperature,and velocity fields are presented for the case of α=45° and discussion is also made concerning the comparison between the numerical and experimental results for the specific case of α=90°。

  14. Polyak type equations for virtual arrow diagram formulas in the annulus

    OpenAIRE

    Mortier, Arnaud

    2012-01-01

    21 pages, 15 figures; We describe the space of arrow diagram formulas for virtual knot diagrams in the annulus as the kernel of a linear map, inspired from a conjecture due to M. Polyak. As a main application, we slightly improve Grishanov-Vassiliev's theorem for planar chain invariants.

  15. Heat Transfer in Tubing-Casing Annulus during Production Process of Geothermal Systems

    Institute of Scientific and Technical Information of China (English)

    Fuzong Zhou; Xiuhua Zheng

    2015-01-01

    In geothermal systems, the temperature distribution of heat flow in the wellbore is de-pendent on the well structure and the geological conditions of the surrounding formation. Under-standing of heat transfer in the tubing-casing annulus can reduce the heat losses of wellbore fluid during the production process. The present study discusses the possible means of heat transfer in the annulus, and develops a piecewise equation for estimating the convective heat transfer coefficient with a wider valid condition of 0annulus. The results indicate that the annulus filled with gas can be utilized as a good thermal barrier for the fluid in the wellbore. Additionally, the contribution of radiation will increase to occupy a majority proportion in the total thermal conductivity when the annular size increases and the materials have high emissivity. Otherwise, thermal radiation is just the second fac-tor.

  16. Damping of a fluid-conveying pipe surrounded by a viscous annulus fluid

    Science.gov (United States)

    Kjolsing, Eric J.; Todd, Michael D.

    2017-04-01

    To further the development of a downhole vibration based energy harvester, this study explores how fluid velocity affects damping in a fluid-conveying pipe stemming from a viscous annulus fluid. A linearized equation of motion is formed which employs a hydrodynamic forcing function to model the annulus fluid. The system is solved in the frequency domain through the use of the spectral element method. The three independent variables investigated are the conveyed fluid velocity, the rotational stiffness of the boundary (using elastic springs), and the annulus fluid viscosity. It was found that, due to the hydrodynamic functions frequency-dependence, increasing the conveyed fluid velocity increases the systems damping ratio. It was also noted that stiffer systems saw the damping ratio increase at a slower rate when compared to flexible systems as the conveyed fluid velocity was increased. The results indicate that overestimating the stiffness of a system can lead to underestimated damping ratios and that this error is made worse if the produced fluid velocity or annulus fluid viscosity is underestimated. A numeric example was provided to graphically illustrate these errors. Approved for publication, LA-UR-15-28006.

  17. Measurement of the aortic annulus size by real-time three-dimensional transesophageal echocardiography.

    Science.gov (United States)

    Jánosi, Rolf Alexander; Kahlert, Philipp; Plicht, Björn; Wendt, Daniel; Eggebrecht, Holger; Erbel, Raimund; Buck, Thomas

    2011-04-01

    We sought to determine the level of agreement and the reproducibility of two-dimensional (2D) transthoracic (2D-TTE), 2D transesophageal (2D-TEE) and real-time three-dimensional (3D) transesophageal echocardiography (RT3D-TEE) for measurement of aortic annulus size in patients referred for transcatheter aortic valve implantation (TAVI). Accurate preoperative assessment of the dimensions of the aortic annulus is critical for patient selection and successful implantation in those undergoing TAVI for severe aortic stenosis (AS). Annulus size was measured using 2D-TTE, 2D-TEE and RT3D-TEE in 105 patients with severe AS referred for TAVI. Agreement between echocardiographic methods and interobserver variability was assessed using the Bland-Altman method and regression analysis, respectively. The mean aortic annuli were 21,7 ± 3 mm measured with 2D-TTE, 22,6 ± 2,8 mm with 2D-TEE and 22,3 ± 2,9 mm with RT3D-TEE. The results showed a small but significant mean difference and a strong correlation between the three measurement techniques (2D-TTE vs. 2D-TEE mean difference 0,84 ± 1,85 mm, r = 0,8, p annulus measured by 2D-TTE, 2D-TEE and RT3D-TEE. Thus, in patients referred for TAVI, the echocardiographic method used may have an impact on TAVI strategy.

  18. The Lawn Hill annulus: An Ordovician meteorite impact into water-saturated dolomite

    Science.gov (United States)

    Darlington, Vicki; Blenkinsop, Tom; Dirks, Paul; Salisbury, Jess; Tomkins, Andrew

    2016-12-01

    The Lawn Hill Impact Structure (LHIS) is located 250 km N of Mt Isa in NW Queensland, Australia, and is marked by a highly deformed dolomite annulus with an outer diameter of 18 km, overlying low metamorphic grade siltstone, sandstone, and shale, along the NE margin of the Georgina Basin. This study provides detailed field observations from sections of the Lawn Hill annulus and adjacent areas that demonstrate a clear link between the deformation of the dolomite and the Lawn Hill impact. 40Ar-39Ar dating of impact-related melt particles provides a time of impact in the Ordovician (472 ± 8 Ma) when the Georgina Basin was an active depocenter. The timing and stratigraphic thickness of the dolomite sequence in the annulus suggest that there was possibly up to 300 m of additional sedimentary rocks on top of the currently exposed Thorntonia Limestone at the time of impact. The exposed annulus is remarkably well preserved, with preservation attributed to postimpact sedimentation. The LHIS has an atypical crater morphology with no central uplift. The heterogeneous target materials at Lawn Hill were probably low-strength, porous, and water-saturated, with all three properties affecting the crater morphology. The water-saturated nature of the carbonate unit at the time of impact is thought to have influenced the highly brecciated nature of the annulus, and restricted melt production. The impact timing raises the possibility that the Lawn Hill structure may be a member of a group of impacts resulting from an asteroid breakup that occurred in the mid-Ordovician (470 ± 6 Ma).

  19. Establishment of the intervertebral disc degeneration model of rabbits by using homemade puncture needles percutaneous puncturing the anulus fibrosus at surface allocation%经皮穿刺纤维环建立兔腰椎间盘退变模型

    Institute of Scientific and Technical Information of China (English)

    黄杰烽; 郑杨; 夏臣杰; 何川; 赵凯; 杜文喜; 陈俊杰; 童培建

    2016-01-01

    目的:探讨使用自制穿刺针经皮穿刺纤维环制备兔腰椎间盘退变模型的可行性。方法将18只新西兰大白兔分为实验组、假手术组及空白对照组。实验组及假手术组使用自制穿刺针穿刺L3~4、L4~5和L5~6椎间盘位置,实验组穿刺椎间盘深度为5 mm,假手术组钝性穿刺但不损伤椎间盘,空白对照组不作处理。术后3、6、9周每组取2只兔麻醉后行腰椎MRI检查,处死行大体观察并取椎间盘行HE染色及髓核蛋白多糖含量测定。结果术后3周开始实验组MRI信号强度、髓核蛋白多糖含量与其他两组相比明显下降( P<0.05),其后呈逐渐下降趋势,大体观察及HE染色显示实验组髓核及纤维环呈逐渐退变趋势。结论自制穿刺针经皮穿刺纤维环法能成功建立兔腰椎间盘退变模型,具有操作简单、损伤小、动物存活率高等优点。%Objective To establish of rabbit intervertebral disc degeneration models by using homemade puncture needles percutaneous annulus fibrosus puncture and assess the feasibility and controllability. Methods 18 New Zea-land white rabbits were divided into the experimental group, the sham group and the control group. L3~4 , L4~5 and L5~6 discs were punctured by the homemade puncture needles in the experimental group as well as in the sham group. The discs were punctured in the experimental group with a depth of 5mm. The sham group was treated by puncture without damage the discs. 2 rabbits were used to observe the anatomical structures. Two rabbits were anesthetized in 3, 6 and 9 weeks respectively after operation for MRI images. Then the animals were killed, the change of lumbar in-tervertebral discs was observed by MRI, histological and nucleus proteoglycan contents were measured. Results All animals were survived, no death, infection, paralysis and other complications. Signal intensity of the intervention group showed a progressive downtrend at 3 weeks after intervention (P<0

  20. Most recent developments for monitoring and controlling the annulus conditions of Marlim-Sul flexible risers

    Energy Technology Data Exchange (ETDEWEB)

    Rabelo, Alexandre S.; Motta, Antonio; Romero, Antonio; Nunes, Joao P.; Zaganelli Junior, Jose L.; Brack, Marcelo [PETROBRAS, Rio de Janeiro, RJ (Brazil)

    2009-07-01

    The main objective of this paper is to present the recent developments for monitoring and controlling the annulus conditions of flexible risers. PETROBRAS has been monitoring the pressure of permeated gas in the annulus region of some risers in order to infer the eventual occurrence of non-conformities as damage on the riser external sheath, for example. Such occurrence would affect the permeated gas flow pattern, the gas pressurization period and the relief valve opening frequencies. Furthermore, the mentioned occurrence would increase the susceptibility of the steel armors to experience the potential failure mechanism of corrosion. In PETROBRAS, the current monitoring method is characterized by visual and periodic manometer readings from a manometer set installed near each riser end-fitting. The data is recorded in a daily report and analyzed by personnel onshore, who are in charge of comparing data and requesting relief valve's actuation, whenever necessary. The paper illustrates Marlim-Sul Asset experience on monitoring and data processing to control the annulus conditions of flexible risers during operation. It presents the in-house developed methodology to data management and processing. This methodology is based on a daily analysis of the permeated gas data worksheet. Some examples are given to illustrate it. The paper also summarizes current developments, in progress, in order to improve riser integrity management. The first development is being done to implement, in the future, automatic data acquisition and control systems. The purpose of automating this process is to improve methods and techniques for data acquisition, transmission and processing. The second development focuses on applications in which riser top end-fittings are submerged. In this particular scenario, a special system - with a quick connection sub sea device - is under development to allow the connection, by divers, after the riser pull-in, of the riser annulus to the platform gas

  1. Transplantation of gene-modified nucleus pulposus cells reverses rabbit intervertebral disc degeneration

    Institute of Scientific and Technical Information of China (English)

    LIU Yong; LI Jian-min; HU You-gu

    2011-01-01

    Background Intervertebral disc degeneration is the main cause of low back pain. The purpose of this study was to explore potential methods for reversing the degeneration of lumbar intervertebral discs by transplantation of gene-modified nucleus pulposus cells into rabbit degenerative lumbar intervertebral discs after transfecting rabbit nucleus pulposus cells with adeno-associated virus 2 (AAV2)-mediated connective tissue growth factor (CTGF) and tissue inhibitor of metalloproteinases 1 (TIMP1) genes in vitro.Methods Computer tomography (CT)-guided percutaneous annulus fibrosus injury was performed to build degenerative lumbar intervertebral disc models in 60 New Zealand white rabbits. rAAV2-CTGF-IRES-TIMP1-transfected rabbit nucleus pulposus cells were transplanted into degenerative lumbar intervertebral discs (transplantation group),phosphate-buffered saline (PBS) was injected into degenerative lumbar intervertebral discs (degeneration control group)and normal lumbar intervertebral discs served as a blank control group. After 6, 10 and 14 weeks, the disc height index (DHI) and signal intensity in intervertebral discs were observed by X-ray and magnetic resonance imaging (MRI) analysis.The expression of CTGF and TIMP1 in nucleus pulposus tissue was determined by Western blotting analysis, the synthesis efficiency of proteoglycan was determined by a 35S-sulfate incorporation assay, and the mRNA expression of type Ⅱ collagen and proteoglycan was detected by RT-PCR.Results MRI confirmed that degenerative intervertebral discs appeared two weeks after percutaneous puncture.Transgenic nucleus pulposus cell transplantation could retard the rapid deterioration of the DHI. MRI indicated that degenerative intervertebral discs were relieved in the transplantation group compared with the degeneration control group. The expression of collagen Ⅱ mRNA and proteoglycan mRNA was significantly higher in the transplantation group and the blank control group compared with the

  2. Laboratory experiments in a baroclinic annulus with heating and cooling on the horizontal boundaries

    Science.gov (United States)

    Miller, T. L.; Fowlis, W. W.

    1986-01-01

    Experiments have been performed in a cylindrical annulus with horizontal temperature gradients imposed upon the horizontal boundaries and in which the vertical depth was smaller than the width of the annulus. Qualitative observations were made by the use of small, suspended, reflective flakes in the liquid (water). Four basic regimes of flow were observed: (1) axisymmetric flow, (2) deep cellular convection, (3) boundary layer convective rolls, and (4) baroclinic waves. In some cases there was a mix of baroclinic and convective instabilities present. As a 'mean' interior Richardson number was decreased from a value greater than unity to one less than zero, axisymmetric baroclinic instability of the Solberg type was never observed. Rather, the transition was from non-axisymmetric baroclinic waves, to a mix of baroclinic and convective instability, to irregular cellular convection.

  3. The cyclicity of the period annulus of a quadratic reversible system with one center of genus one

    OpenAIRE

    PENG, Linping; Sun, Yannan

    2014-01-01

    This paper is concerned with a quadratic reversible and non-Hamiltonian system with one center of genus one. By using the properties of related elliptic integrals and the geometry of some planar curves defined by them, we prove that the cyclicity of the period annulus of the considered system under small quadratic perturbations is two. This verifies Gautier's conjecture about the cyclicity of the related period annulus.

  4. The cyclicity of the period annulus of a quadratic reversible system with one center of genus one

    OpenAIRE

    PENG, Linping; Sun, Yannan

    2011-01-01

    This paper is concerned with a quadratic reversible and non-Hamiltonian system with one center of genus one. By using the properties of related elliptic integrals and the geometry of some planar curves defined by them, we prove that the cyclicity of the period annulus of the considered system under small quadratic perturbations is two. This verifies Gautier's conjecture about the cyclicity of the related period annulus.

  5. Hysteresis and the transition between axisymmetric flow and wave flow in the baroclinic annulus

    Science.gov (United States)

    Miller, Timothy L.; Butler, Karen A.

    1991-01-01

    A numerical model is employed to establish the transitions between axisymmetric flow and wave flow in the rotating, differentially heated annulus experiments of Fein for both rigid lid and free surface cases. It is shown that, for most of the transitions, the method of computing a steady axisymmetric flow and then testing its linear stability to wave disturbance results in good agreement with the experiments. Implications for the investigation of the dynamics of the earth's atmosphere are considered.

  6. Centrifugally driven convection in the rotating cylindrical annulus with modulated boundaries

    Directory of Open Access Journals (Sweden)

    M. Westerburg

    2003-01-01

    Full Text Available The effect of sinusoidally modulated conical end boundaries on convection in a rotating cylindrical annulus is investigated theoretically and experimentally. A quasiperiodic time dependence of convection in the form of thermal Rossby waves is found and semi-quantitative agreement between theory and measurements can be established. The results are relevant to convection in the Earth's outer core close to the tangent cylinder touching the inner core at its equator.

  7. The Influence of Horizontal Boundaries on Ekman Circulation and Angular Momentum Transport in a Cylindrical Annulus

    OpenAIRE

    Obabko, Aleksandr V.; Cattaneo, Fausto; Fischer, Paul F.

    2008-01-01

    We present numerical simulations of circular Couette flow in axisymmetric and fully three-dimensional geometry of a cylindrical annulus inspired by Princeton MRI liquid gallium experiment. The incompressible Navier-Stokes equations are solved with the spectral element code Nek5000 incorporating realistic horizontal boundary conditions of differentially rotating rings. We investigate the effect of changing rotation rates (Reynolds number) and of the horizontal boundary conditions on flow struc...

  8. A Fast Stble Marching Scheme for Calculating Mixed Convection in a Vertical Rotating Annulus

    Institute of Scientific and Technical Information of China (English)

    Chao-MinZhang; Zeng-YuanGuo

    1993-01-01

    An iterative simultanous solution method is developed to efficiently solve the Newton-Raphson linear equation set for velocity in three dimensions,pressure and temperature,The proposed method is demonstrated for several cases of the thermal drive in a vertical rotating annulus,and is shown to be insensitive to dimensionless time step,requiring significantly less computational effort to converge to the desired accuracy than SIMPLEC,even for low Prandtl number fluid flows.

  9. [Evaluation of aortic valve replacement involving small severely calcified aortic annulus in elderly patients].

    Science.gov (United States)

    Iwahashi, M; Nishimura, Y; Hiramatsu, K; Komori, S; Shibata, M; Yuzaki, M; Okamura, Y

    2006-04-01

    We performed aortic valve replacement in 24 patients aged over 70 with small calcified valves. The surgical management of such patients remains controversial as the extensive calcification compromises implantation. Hence, we used an ultrasonic debridement instrument to remove calcium and selected a small prosthesis with the largest possible orifice without enlargement of the aortic annulus. Echocardiography showed significant reductions in left ventricular mass index compared with preoperative values. Early and mid-term prognosis has been relatively good.

  10. Hydraulic resistance of plane channels and annulus with different roughness on opposite walls

    Science.gov (United States)

    Korsun, A. S.; Kutsenko, K. V.; Pisarevsky, M. I.; Fedoseev, V. N.; Balberkina, Y. N.

    2017-03-01

    A new method for prediction of hydraulic resistance for a turbulent flow in plane channels and annulus is proposed. In spite of the importance of this issue, only very few publications devoted to the investigation into hydrodynamics in these channels are available, and there are no methods for predicting hydraulic resistance of a flow in these channels at all. The flow in channels with different roughness on the walls is described using the Prandtl semiempirical theory of a turbulent boundary layer. The flow in a channel cross-section is divided into two noninteracting layers of different thickness flowing along the walls with different roughness. The basic balance correlations are derived for a plane channel. To match the velocity profiles of both layers at the interface point, a logarithmic velocity profile is used. This yields a closed system of equations for predicting hydraulic resistance in plane channels with a given different roughness on opposite walls. It is demonstrated that the obtained correlation may be used for predicting hydraulic resistance in annulus as well. Experiments were carried out with a water flow in an annulus. Each annuli consisted of a pipe having a smooth wall into which a rod with artificial roughness on the surface was inserted coaxially. Two types of roughness were investigated: trapezoid and threadlike ones. Comparison of the predictions with the experimental data confirmed the validity of the proposed method. It can be used in designing flowpaths of various power installations.

  11. Annulus formation on scales of four species of coregonids reared under artificial conditions

    Science.gov (United States)

    Hogman, Walter J.

    1968-01-01

    Scales from known-age coregonids reared in the laboratory were examined to determine when annuli formed and to learn possible factors of their formation. Scales were taken monthly from marked fish for periods up to 21 months. Scales were also examined from fish that died and from preserved specimens of young-of-the-year for each species. Two marks formed on almost all scales each calender year. The stronger formed during March-April and the weaker in October-November. Both marks had all the usual characteristics of an annulus but the spring mark was considered the annulus and the fall mark an accessory check. The annulus formed during a period of constant temperatures and of little change in growth or increasing growth. The accessory check formed during a period of declining temperatures (1-5 degrees F, or 0.6-2.8 degrees C, per month) and of little change in growth or declining growth. Most fish grew throughout the winter; the only exceptions were one bloater (Coregonus hoyi) and several of the largest lake whitefish (C. clupeaformis). Fish were always given all the food they would eat to eliminate availability of food as a factor of mark formation. The temperature of the water during the winter (50 ±. 0.3 F; 10.0 ±. 0.2 C) did not arrest metabolic activity. The growth rate was related more closely to day length than to other variables examined.

  12. SMART MONITORING AND DECISION MAKING FOR REGULATING ANNULUS BOTTOM HOLE PRESSURE WHILE DRILLING OIL WELLS

    Directory of Open Access Journals (Sweden)

    M. P. Vega

    Full Text Available Abstract Real time measurements and development of sensor technology are research issues associated with robustness and safety during oil well drilling operations, making feasible the diagnosis of problems and the development of a regulatory strategy. The major objective of this paper is to use an experimental plant and also field data, collected from a basin operation, offshore Brazil, for implementing smart monitoring and decision making, in order to assure drilling inside operational window, despite the commonly observed disturbances that produce fluctuations in the well annulus bottom hole pressure. Using real time measurements, the performance of a continuous automated drilling unit is analyzed under a scenario of varying levels of rate of penetration; aiming pressure set point tracking (inside the operational drilling window and also rejecting kick, a phenomenon that occurs when the annulus bottom hole pressure is inferior to the porous pressure, producing the migration of reservoir fluids into the annulus region. Finally, an empirical model was built, using real experimental data from offshore Brazil basins, enabling diagnosing and regulating a real drilling site by employing classic and advanced control strategies.

  13. Cubic autocatalysis in a reaction-diffusion annulus: semi-analytical solutions

    Science.gov (United States)

    Alharthi, M. R.; Marchant, T. R.; Nelson, M. I.

    2016-06-01

    Semi-analytical solutions for cubic autocatalytic reactions are considered in a circularly symmetric reaction-diffusion annulus. The Galerkin method is used to approximate the spatial structure of the reactant and autocatalyst concentrations. Ordinary differential equations are then obtained as an approximation to the governing partial differential equations and analyzed to obtain semi-analytical results for this novel geometry. Singularity theory is used to determine the regions of parameter space in which the different types of steady-state diagram occur. The region of parameter space, in which Hopf bifurcations can occur, is found using a degenerate Hopf bifurcation analysis. A novel feature of this geometry is the effect, of varying the width of the annulus, on the static and dynamic multiplicity. The results show that for a thicker annulus, Hopf bifurcations and multiple steady-state solutions occur in a larger portion of parameter space. The usefulness and accuracy of the semi-analytical results are confirmed by comparison with numerical solutions of the governing partial differential equations.

  14. Localized strain measurements of the intervertebral disc annulus during biaxial tensile testing.

    Science.gov (United States)

    Karakolis, Thomas; Callaghan, Jack P

    2015-01-01

    Both inter-lamellar and intra-lamellar failures of the annulus have been described as potential modes of disc herniation. Attempts to characterize initial lamellar failure of the annulus have involved tensile testing of small tissue samples. The purpose of this study was to evaluate a method of measuring local surface strains through image analysis of a tensile test conducted on an isolated sample of annular tissue in order to enhance future studies of intervertebral disc failure. An annulus tissue sample was biaxial strained to 10%. High-resolution images captured the tissue surface throughout testing. Three test conditions were evaluated: submerged, non-submerged and marker. Surface strains were calculated for the two non-marker conditions based on motion of virtual tracking points. Tracking algorithm parameters (grid resolution and template size) were varied to determine the effect on estimated strains. Accuracy of point tracking was assessed through a comparison of the non-marker conditions to a condition involving markers placed on tissue surface. Grid resolution had a larger effect on local strain than template size. Average local strain error ranged from 3% to 9.25% and 0.1% to 2.0%, for the non-submerged and submerged conditions, respectively. Local strain estimation has a relatively high potential for error. Submerging the tissue provided superior strain estimates.

  15. Radiofrequency catheter ablation of idiopathic ventricular tachycardia and symptomatic premature ventricular contraction originating from valve annulus

    Institute of Scientific and Technical Information of China (English)

    WU Xiao-yu; LIANG Zhao-guang; TAN Zhen; GU Hong-yue; ZHANG Shu; LI Wei-min

    2008-01-01

    Background Radiofrequency catheter ablation (RFCA) has been established as an effective and curative therapy for ventricular tachycardia (VT) and severely symptomatic premature ventricular contraction (PVC) from the outflow tract in structurally normal hearts.This study aimed to investigate electrophysiologic characteristics and effects of RFCA for patients with idiopathic VT and symptomatic PVC originating from the valve annulus.Methods Characteristics of body surface electrocardiogram (ECG) and endocardiogram in a successful RFCA target were analyzed in 16 patients with idiopathic VT and symptomatic PVC originating from the valve annulus.Additionally,the ECG characteristics of vr or PVC were compared with those of manifest Wolff-Parkinson-White (WPW) syndrome originating from the same site of origin in 15 patients.Results Thirteen patients were successful,2 recurrent and 1 failed.The recurrent cases underwent successful ablation the second time guided by the Ensite 3000 mapping system.In all patients with the WPW syndrome,the characteristics of QRS morphology were well matched with those of the VT and PVC that originated from corresponding sites of origin.Conclusions RFCA is an effective curative therapy for VT and symptomatic PVC originating from the valve annulus.There are specific characteristics in ECG and the ablation site could be located by means of the WPW syndrome accessory pathway's algorithm.

  16. Constant-flux discrete heating in a unit aspect-ratio annulus

    Science.gov (United States)

    Lopez, J. M.; Sankar, M.; Do, Younghae

    2012-10-01

    Natural convection in an annulus with a discrete heat source on the inner cylinder is studied numerically. The outer cylinder is isothermally cooled at a fixed low temperature, and the top wall, the bottom wall and unheated portions of the inner cylinder are thermally insulated. For low applied heat flux through the heater, as measured non-dimensionally by a Grashof number, Gr, the flow in the annular gap consists of a single-cell overturning meridional flow driven by the radial temperature gradient between the heater on the inner cylinder and the cold outer cylinder. In this regime, the flow is very weak and heat is transported primarily via conduction. The flow structure does not change until Gr ˜ 104, although the flow strength steadily increases with Gr. As the nonlinear convection terms become more important, the meridional circulation sweeps the isotherms from being almost vertical near the outer cylinder to almost horizontal near the bottom wall. By the end of the transition from the conduction-dominated regime (Gr vertical levels below that of the bottom of the heater, an essentially cold stagnant pool develops, with the heat flux through the outer cylinder dropping to zero. (ii) At vertical levels between the bottom and the top of the heater, most of the region in between the two cylinders is stably stratified with a relatively weak radial flow from the cold to the heated cylinder. The horizontal isotherms adjust to the temperatures on the cylinders in thin buoyancy boundary layers which drive fluid down the cold cylinder and up the heated cylinder segment. The boundary layer on the heater is about half as thick as that on the cold cylinder, but about twice as intense. (iii) The third region is above the heater top. The boundary layer flow from the heater continues upward where it meets the top endwall and bounces off of it. A wavy jet bounces on its way radially outward between the top insulated wall and the stably stratified region below. Flow

  17. Interobserver variability of CT angiography for evaluation of aortic annulus dimensions prior to transcatheter aortic valve implantation (TAVI)

    Energy Technology Data Exchange (ETDEWEB)

    Schmidkonz, C., E-mail: christian.schmidkonz@gmail.com [Department of Internal Medicine 2 (Cardiology), University of Erlangen, Ulmenweg 18, D-91054 Erlangen (Germany); Marwan, M.; Klinghammer, L.; Mitschke, M.; Schuhbaeck, A.; Arnold, M. [Department of Internal Medicine 2 (Cardiology), University of Erlangen, Ulmenweg 18, D-91054 Erlangen (Germany); Lell, M. [Radiological Institute, University of Erlangen, Maximiliansplatz 1, D-91054 Erlangen (Germany); Achenbach, S.; Pflederer, T. [Department of Internal Medicine 2 (Cardiology), University of Erlangen, Ulmenweg 18, D-91054 Erlangen (Germany)

    2014-09-15

    Highlights: • Cardiac CT provides highly reproducible measurements of aortic annulus and root dimensions prior to TAVI. • The perimeter-derived aortic annulus diameter shows the lowest interobserver variability. • If all three CT sizing methods are considered and stated as a “consensus result”, mismatches in prosthesis size selection can be further reduced. - Abstract: Objective: Assessment of aortic annulus dimensions prior to transcatheter aortic valve implantation (TAVI) is crucial for accurate prosthesis sizing in order to avoid prosthesis–annulus-mismatch possibly resulting in complications like valve dislodgement, paravalvular regurgitation or annulus rupture. Contrast-enhanced multidetector computed tomography allows 3-dimensional assessment of aortic annulus dimensions. Only limited data exist about its interobserver variability. Methods: In 100 consecutive patients with symptomatic severe aortic stenosis (51 male, BMI 27 ± 5 kg/m{sup 2}, age 81 ± 7 years, heart rate 72 ± 15 bpm, Logistic Euroscore 31 ± 14%, STS-Score 7 ± 4%), pre-interventional aortic annulus assessment was performed by dual source computed tomography (collimation 2 × 128 × 0.6 mm, high pitch spiral data acquisition mode, 40–60 ml contrast agents, radiation dose 3.5 ± 0.9 mSv). The following aortic annulus characteristics were determined by three independent observers: aortic annulus maximum, minimum and mean diameters (D{sub max}, D{sub min}, D{sub mean}), eccentricity index (EI), effective aortic annulus diameter according to its circumference (D{sub circ}), effective aortic annulus diameter according to its area (D{sub area}), distance from the aortic annulus plane to the left (LCA) and right coronary artery (RCA) ostia, maximum (D{sub max}AR) and minimum aortic root diameter (D{sub min}AR), maximum (D{sub max}STJ) and minimum diameter of the sinotubular junction (D{sub min}STJ). Subsequently, interobserver variabilities were assessed. Results: Correlation between

  18. Flow regime transition criteria for two-phase flow in a vertical annulus

    Energy Technology Data Exchange (ETDEWEB)

    Julia, J. Enrique, E-mail: bolivar@emc.uji.es [Departamento de Ingenieria Mecanica y Construccion, Universitat Jaume I., Campus de Riu Sec, 12071 Castellon (Spain); Hibiki, Takashi [School of Nuclear Engineering, Purdue University, 400 Central Dr., West Lafayette, IN 47907-2017 (United States)

    2011-10-15

    Highlights: > Flow regime transition model is presented for two-phase flows in a vertical annulus. > The transition criteria is easy to be implemented in computational codes. > Final equations do not need experimental input. > New developed model shows better predicting capabilities than existing correlations. > New developed model shows good predicting capabilities in boiling flow. - Abstract: In this work, a new flow regime transition model is proposed for two-phase flows in a vertical annulus. Following previous works, the flow regimes considered are bubbly (B), slug (S) or cap-slug (CS), churn (C) and annular (A). The B to CS transition is modeled using the maximum bubble package criteria of small bubbles. The S to C transition takes place for small annulus perimeter flow channels and it is assumed to occur when the mean void fraction over the entire region exceeds that over the slug-bubble section. If the annulus perimeter is larger that the distorted bubble limit the cap-slug flow regime will be considered since in these conditions it is not possible to distinguish between cap and partial-slug bubbles. The CS to C transition is modeled using the maximum bubble package criteria. However, this transition considers the coalescence of cap and spherical bubbles in order to take into account the flow channel geometry. Finally, the C to A transition is modeled assuming two different mechanisms, (a) flow reversal in the liquid film section along large bubbles; (b) destruction on liquid slugs or large waves by entrainment or deformation. In the S to C and C to A flow regime transitions the annulus flow channel is considered as a rectangular flow channel with no side walls. In all the modeled transitions the drift-flux model is used to obtain the final correlations. The final equations for every flow regime transition are easy to be implemented in computational codes and not experimental input is needed. The prediction accuracy of the newly developed model has been

  19. Multi-detector computed tomography is equivalent to trans-oesophageal echocardiography for the assessment of the aortic annulus before transcatheter aortic valve implantation

    Energy Technology Data Exchange (ETDEWEB)

    Rixe, Johannes; Schmitt, Joern; Neumann, Thomas; Hamm, Christian W.; Rolf, Andreas [Kerckhoff Heart and Thorax Center, Department of Cardiology, Bad Nauheim (Germany); University Hospital of Giessen and Marburg, Site Giessen, Department of Internal Medicine I (Cardiology, Angiology), Giessen (Germany); Schuhbaeck, Annika; Nef, Holger M.; Achenbach, Stephan [University Hospital of Giessen and Marburg, Site Giessen, Department of Internal Medicine I (Cardiology, Angiology), Giessen (Germany); Liebetrau, Christoph; Moellmann, Helge; Szardien, Sebastian; Brandt, Roland [Kerckhoff Heart and Thorax Center, Department of Cardiology, Bad Nauheim (Germany); Schneider, Christian; Krombach, Gabriele [University Hospital of Giessen and Marburg, Department of Radiology, Giessen (Germany)

    2012-12-15

    In transcatheter aortic valve implantation (TAVI), assessment of the aortic annulus is mandatory. We sought to investigate the correlation between trans-oesophageal echocardiography (TEE) and multi-detector computed tomography (MDCT) for annulus diameter assessment before TAVI. A total of 122 patients (67 male, mean age 84 {+-} 6 years) underwent MDCT and TEE for TAVI planning. In TEE annulus diameters were obtained in a long-axis view at diastole. MDCT data were evaluated using MPR images, and corresponding projections were adjusted for MDCT and TEE. Patients were classified by the predominant localisation of aortic valve calcifications, and annulus diameters between TEE and MDCT were correlated. Additionally, the eccentricity of the aortic annulus was calculated. Mean eccentricity of the aortic annulus determined by MDCT was 0.34 {+-} 0.17, with no difference according to valve calcification. Regarding the aortic annulus diameter, the mean values measured were 24.3 {+-} 2.1 mm in MDCT and 24.0 {+-} 2.5 mm in TEE (P < 0.0001 for agreement). Independent of the pattern of aortic valve calcification, close correlation is found between CT and TEE measurements of the aortic annulus diameter. In addition, CT demonstrates the non-circular shape of the aortic annulus. (orig.)

  20. CHARACTERIZATION OF TANK 16H ANNULUS SAMPLES PART II: LEACHING RESULTS

    Energy Technology Data Exchange (ETDEWEB)

    Hay, M.; Reboul, S.

    2012-06-19

    The closure of Tank 16H will require removal of material from the annulus of the tank. Samples from Tank 16H annulus were characterized and tested to provide information to evaluate various alternatives for removing the annulus waste. The analysis found all four annulus samples to be composed mainly of Si, Na, and Al and lesser amounts of other elements. The XRD data indicate quartz (SiO{sub 2}) and sodium aluminum nitrate silicate hydrate (Na{sub 8}(Al{sub 6}Si{sub 6}O{sub 24})(NO{sub 3}){sub 2}.4H{sub 2}O) as the predominant crystalline mineral phases in the samples. The XRD data also indicate the presence of crystalline sodium nitrate (NaNO{sub 3}), sodium nitrite (NaNO{sub 2}), gibbsite (Al(OH){sub 3}), hydrated sodium bicarbonate (Na{sub 3}H(CO{sub 3}){sub 2}.2H{sub 2}O), and muscovite (KAl{sub 2}(AlSi{sub 3}O{sub 10})(OH){sub 2}). Based on the weight of solids remaining at the end of the test, the water leaching test results indicate 20-35% of the solids dissolved after three contacts with an approximately 3:1 volume of water at 45 C. The chemical analysis of the leachates and the XRD results of the remaining solids indicate sodium salts of nitrate, nitrite, sulfate, and possibly carbonate/bicarbonate make up the majority of the dissolved material. The majority of these salts were dissolved in the first water contact and simply diluted with each subsequent water contact. The water leaching removed large amounts of the uranium in two of the samples and approximately 1/3 of the {sup 99}Tc from all four samples. Most of the other radionuclides analyzed showed low solubility in the water leaching test. The oxalic acid leaching test result indicate approximately 34-47% of the solids in the four annulus samples will dissolve after three contacts with an approximately 3:1 volume of acid to solids at 45 C. The same sodium salts found in the water leaching test comprise the majority of dissolved material in the oxalic acid leaching test. However, the oxalic acid was

  1. ANNULUS CLOSURE TECHNOLOGY DEVELOPMENT INSPECTION/SALT DEPOSIT CLEANING MAGNETIC WALL CRAWLER

    Energy Technology Data Exchange (ETDEWEB)

    Minichan, R; Russell Eibling, R; James Elder, J; Kevin Kane, K; Daniel Krementz, D; Rodney Vandekamp, R; Nicholas Vrettos, N

    2008-06-01

    The Liquid Waste Technology Development organization is investigating technologies to support closure of radioactive waste tanks at the Savannah River Site (SRS). Tank closure includes removal of the wastes that have propagated to the tank annulus. Although amounts and types of residual waste materials in the annuli of SRS tanks vary, simple salt deposits are predominant on tanks with known leak sites. This task focused on developing and demonstrating a technology to inspect and spot clean salt deposits from the outer primary tank wall located in the annulus of an SRS Type I tank. The Robotics, Remote and Specialty Equipment (RRSE) and Materials Science and Technology (MS&T) Sections of the Savannah River National Laboratory (SRNL) collaborated to modify and equip a Force Institute magnetic wall crawler with the tools necessary to demonstrate the inspection and spot cleaning in a mock-up of a Type I tank annulus. A remote control camera arm and cleaning head were developed, fabricated and mounted on the crawler. The crawler was then tested and demonstrated on a salt simulant also developed in this task. The demonstration showed that the camera is capable of being deployed in all specified locations and provided the views needed for the planned inspection. It also showed that the salt simulant readily dissolves with water. The crawler features two different techniques for delivering water to dissolve the salt deposits. Both water spay nozzles were able to dissolve the simulated salt, one is more controllable and the other delivers a larger water volume. The cleaning head also includes a rotary brush to mechanically remove the simulated salt nodules in the event insoluble material is encountered. The rotary brush proved to be effective in removing the salt nodules, although some fine tuning may be required to achieve the best results. This report describes the design process for developing technology to add features to a commercial wall crawler and the results of the

  2. Comparison of aortic annulus diameter measurement between multi-detector computed tomography and echocardiography: a meta-analysis.

    Directory of Open Access Journals (Sweden)

    Ruifang Zhang

    Full Text Available BACKGROUND AND PURPOSE: Accurate measurement of aortic annulus diameter is crucial for choosing suitable prosthetic size for transcatheter aortic valve implantation (TAVI. Several imaging methods are available for the measurement, but significant variability between different modalities has been observed. The purpose of this study was to systematically compare the measurements of aortic annulus diameter between multi-detector computed tomography (MDCT, transthoracic echocardiography (TTE, and transesophegeal echocardiography (TEE. METHODS: PubMed and EMBASE databases between January 2000 and January 2012 were searched. We extracted data from eligible studies evaluating the aortic annulus diameter by MDCT and echocardiography (TTE, TEE, or both. We performed a random-effects meta-analysis to calculate the weighted mean differences of aortic annulus diameter measurement between MDCT, TTE, and TEE. RESULTS: A total of 10 eligible studies involving 581 subjects with aortic valve stenosis were included. Aortic annulus diameter measured on coronal view by MDCT (25.3±0.52 mm was respectively larger than that measured on sagittal view by MDCT (22.7±0.37 mm, TTE (22.6±0.28 mm, and TEE (23.1±0.32 mm. The weighted mean difference of aortic annulus diameter between coronal view by MDCT and TTE these two methods was 2.97 mm, followed by the weighted mean difference of 2.53 mm between coronal view and sagittal view by MDCT, and the mean difference of 1.74 mm between coronal view on MDCT and TEE (P<0.0001 for all. The weighted mean difference of aortic annulus diameter measurement between TEE and TTE was significant but somewhat small (0.45 mm, P = 0.007. CONCLUSION: Aortic annulus diameter measured on coronal view by MDCT was robustly and significantly larger than that obtained on sagittal view by MDCT, TTE, or TEE. Such variability of aortic annulus diameter measurement by different imaging modalities cannot be ignored when developing optimal

  3. Conjugated Conduction-Free Convection Heat Transfer in an Annulus Heated at Either Constant Wall Temperature or Constant Heat Flux

    Directory of Open Access Journals (Sweden)

    HAROON IMTIAZ

    2017-04-01

    Full Text Available In this paper, we investigate numerically the effect of thermal boundary conditions on conjugated conduction-free convection heat transfer in an annulus between two concentric cylinders using Fourier Spectral method. The inner wall of the annulus is heated and maintained at either CWT (Constant Wall Temperature or CHF (Constant Heat Flux, while the outer wall is maintained at constant temperature. CHF case is relatively more significant for high pressure industrial applications, but it has not received much attention. This study particularly focuses the latter case (CHF. The main influencing parameters on flow and thermal fields within the annulus are: Rayleigh number Ra; thickness of inner wall Rs; radius ratio Rr and inner wall-fluid thermal conductivity ratio Kr. The study has shown that the increase in Kr increases the heat transfer rate through the annulus for heating at CWT and decreases the inner wall dimensionless temperature for heating at CHF and vice versa. It has also been proved that as the Rs increases at fixed Ra and Rr, the heat transfer rate decreases for heating at CWT and the inner wall dimensionless temperature increases for heating at CHF at Kr 1 depends on Rr. It has been shown that for certain combinations of controlling parameters there will be a value of Rr at which heat transfer rate will be minimum in the annulus in case of heating at CWT, while

  4. The Influence of Horizontal Boundaries on Ekman Circulation and Angular Momentum Transport in a Cylindrical Annulus

    CERN Document Server

    Obabko, Aleksandr V; Fischer, Paul F

    2008-01-01

    We present numerical simulations of circular Couette flow in axisymmetric and fully three-dimensional geometry of a cylindrical annulus inspired by Princeton MRI liquid gallium experiment. The incompressible Navier-Stokes equations are solved with the spectral element code Nek5000 incorporating realistic horizontal boundary conditions of differentially rotating rings. We investigate the effect of changing rotation rates (Reynolds number) and of the horizontal boundary conditions on flow structure, Ekman circulation and associated transport of angular momentum through the onset of unsteadiness and three-dimensionality. A mechanism for the explanation of the dependence of the Ekman flows and circulation on horizontal boundary conditions is proposed.

  5. Cardiac valve annulus manual segmentation using computer assisted visual feedback in three-dimensional image data.

    Science.gov (United States)

    Casero, Ramon; Burton, Rebecca A B; Quinn, T; Bollensdorff, Christian; Hales, Patrick; Schneider, Jurgen E; Kohl, Peter; Grau, Vicente

    2010-01-01

    Annulus manual segmentation is an important tool for the study of valve anatomy and physiology, for the four main valves of the heart (mitral, tricuspid, aortic and pulmonary). In this paper we review two traditional manual segmentation approaches: slice-by-slice and interpolating a sparse set of landmarks with a spline curve. We propose a new Spline Tool for the open source software platform Seg3D, that is fast and improves spatial coherence by providing visual feedback of the segmentation in real time. The Spline Tool was tested successfully on 14 rat hearts, on all four valves.

  6. Modelling of flow boiling heat transfer in a cylindrical annulus mini gap

    Directory of Open Access Journals (Sweden)

    Piasecka Magdalena

    2017-01-01

    Full Text Available This paper presents the results of investigations into flow boiling heat transfer in a mini gap 1 mm wide. The mathematical approaches of the heat transfer coefficient determination were also proposed. It was considered two ways of describing layers in a measurement module with a cylindrical annulus mini gap. In the first approach, the measurement module was treated as a planar multilayer wall and in the second approach - as a multilayer cylindrical wall. The values of the local heat transfer coefficients, determined from two approaches, were compared. Both approaches gave similar results.

  7. Transportation of MHD nanofluid free convection in a porous semi annulus using numerical approach

    Science.gov (United States)

    Sheikholeslami, M.; Ganji, D. D.

    2017-02-01

    Nanofluid free convection in presence of Lorentz forces in a permeable semi annulus is simulated using Control Volume based Finite Element Method. Impact of porous media on governing equations is considered by means of Darcy law. Brownian motion impact on properties of nanofluid is taken into account using Koo-Kleinstreuer-Li (KKL) model. Important parameters are inclination angle (ξ) , CuO-water volume fraction (ϕ) , Hartmann (Ha) and Rayleigh (Ra) numbers for porous medium. A formula for Nuave is provided. Results indicated that temperature gradient detracts with enhance of Ha but it enhances with rise of ξ, Ra . Heat transfer augmentation enhances with rise of Lorentz forces.

  8. Mixed convection aiding flow in a vertical porous annulus-two temperature model

    Science.gov (United States)

    Salman Ahmed, N. J.; AAAl-Rashed, Abdullah A.; Kamangar, Sarfaraz; Khaleed, H. M. T.; YunusKhan, T. M.; Athani, Abdulgaphur

    2016-09-01

    The effect of convective heat transfer on mixed convection flow in a vertical porous annulus embedded with fluid saturated porous medium for aiding flow is studied. The inner surface of the annular cylinder is heated with constant temperature whereas the outer surface remains at ambient temperature. The governing partial differential equations are solved using Finite Element Method (FEM). It is assumed that the Darcy law is applicable and thermal nonequilibrium TNE exists between solid and fluid phases of porous medium. The aiding flow behavior of heat transfer with respect to Radius ratioRr, Aspect ratio ArandRadiation parameter Rd for different values of Peclet number Peare investigated.

  9. The influence of horizontal boundaries on Ekman circulation and angular momentum transport in a cylindrical annulus

    Energy Technology Data Exchange (ETDEWEB)

    Obabko, Aleksandr V; Cattaneo, Fausto [Department of Astronomy and Astrophysics, University of Chicago, Chicago, IL 60637 (United States); F Fischer, Paul [Division of Mathematics and Computer Science, Argonne National Laboratory, Argonne, IL 60439 (United States)], E-mail: obabko@uchicago.edu

    2008-12-15

    We present numerical simulations of circular Couette flow in axisymmetric and fully three-dimensional geometry of a cylindrical annulus inspired by Princeton magnetorotational instability (MRI) liquid gallium experiment. The incompressible Navier-Stokes equations are solved with the spectral element code Nek5000 incorporating realistic horizontal boundary conditions of differentially rotating rings. We investigate the effect of changing rotation rates (Reynolds number) and of the horizontal boundary conditions on flow structure, Ekman circulation and associated transport of angular momentum through the onset of unsteadiness and three-dimensionality. A mechanism for the explanation of the dependence of the Ekman flows and circulation on horizontal boundary conditions is proposed.

  10. Does the mitral annulus shrink or enlarge during systole? A real-time 3D echocardiography study.

    Science.gov (United States)

    Kwan, Jun; Jeon, Min-Jae; Kim, Dae-Hyeok; Park, Keum-Soo; Lee, Woo-Hyung

    2009-04-01

    This study was conducted to explore the geometrical changes of the mitral annulus during systole. The 3D shape of the mitral annulus was reconstructed in 13 normal subjects who had normal structure of the mitral apparatus using real-time 3D echocardiography (RT3DE) and 3D computer software. The two orthogonal (antero-posterior and commissure-commissure) dimensions, the areas (2D projected and 3D surface) and the non-planarity of the mitral annulus were estimated during early, mid and late systole. We demonstrated that the MA had a "saddle shape" appearance and it consistently enlarged mainly in the antero-posterior direction from early to late systole with lessening of its non-planarity, as was determined by 3D reconstruction using RT3DE and 3D computer software.

  11. The break of shielding current at pulsed field magnetization of a superconducting annulus (experiment and model simulation)

    Science.gov (United States)

    Korotkov, V. S.; Krasnoperov, E. P.; Kartamyshev, A. A.

    2017-09-01

    During the pulsed field magnetization of a high-T c annulus in liquid nitrogen the shielding current drops abruptly, providing rapid penetration of the magnetic flux into the hole of the superconductor. After the break of current the trapped field in the hole is small and negative although the body of the annulus remains highly magnetized. In the present work the current breaking effect is investigated both experimentally and numerically. The influence of the pulse parameter on the shielding current evolution during the break is researched. A simple model for the qualitative description of this process is proposed. The model shows the development of heating localized on the inhomogeneity of the high-temperature superconductor annulus providing the formation of a high resistive channel with temperature near to T c. The appearance of this hot channel leads to the rapid reduction of the shielding current and presents a new scenario of flux jump at high temperature.

  12. Creeping gaseous flows through elastic tube and annulus micro-configurations

    Science.gov (United States)

    Elbaz, Shai; Jacob, Hila; Gat, Amir

    2016-11-01

    Gaseous flows in elastic micro-configurations is relevant to biological systems (e.g. alveolar ducts in the lungs) as well as to applications such as gas actuated soft micro-robots. We here examine the effect of low-Mach-number compressibility on creeping gaseous axial flows through linearly elastic tube and annulus micro-configurations. For steady flows, the leading-order effects of elasticity on the pressure distribution and mass-flux are obtained. For transient flow in a tube with small deformations, elastic effects are shown to be negligible in leading order due to compressibility. We then examine transient flows in annular configurations where the deformation is significant compared with the gap between the inner and outer cylinders defining the annulus. Both compressibility and elasticity are obtained as dominant terms interacting with viscosity. For a sudden flux impulse, the governing non-linear leading order diffusion equation is initially approximated by a porous-medium-equation of order 2.5 for the pressure square. However, as the fluid expand and the pressure decreases, the governing equation degenerates to a porous-medium-equation of order 2 for the pressure.

  13. Melting of a phase change material in a horizontal annulus with discrete heat sources

    Directory of Open Access Journals (Sweden)

    Mirzaei Hooshyar

    2015-01-01

    Full Text Available Phase change materials have found many industrial applications such as cooling of electronic devices and thermal energy storage. This paper investigates numerically the melting process of a phase change material in a two-dimensional horizontal annulus with different arrangements of two discrete heat sources. The sources are positioned on the inner cylinder of the annulus and assumed as constant-temperature boundary conditions. The remaining portion of the inner cylinder wall as well as the outer cylinder wall is considered to be insulated. The emphasis is mainly on the effects of the arrangement of the heat source pair on the fluid flow and heat transfer features. The governing equations are solved on a non-uniform O type mesh using a pressure-based finite volume method with an enthalpy porosity technique to trace the solid and liquid interface. The results are obtained at Ra=104 and presented in terms of streamlines, isotherms, melting phase front, liquid fraction and dimensionless heat flux. It is observed that, depending on the arrangement of heat sources, the liquid fraction increases both linearly and non-linearly with time but will slow down at the end of the melting process. It can also be concluded that proper arrangement of discrete heat sources has the great potential in improving the energy storage system. For instance, the arrangement C3 where the heat sources are located on the bottom part of the inner cylinder wall can expedite the melting process as compared to the other arrangements.

  14. Posterior enlargement of the small annulus during aortic valve replacement versus implantation of a small prosthesis.

    Science.gov (United States)

    Pugliese, P; Bernabei, M; Santi, C; Pasqué, A; Eufrate, S

    1984-07-01

    Twenty-two patients with a small aortic annulus were identified among 196 consecutive patients undergoing aortic valve replacement (AVR). The 11 patients in Group 1 underwent posterior enlargement aortic annuloplasty, and the 11 in Group 2 received a small aortic prosthesis (less than or equal to 21 mm). The two groups were unselected. Core hypothermia, cardioplegia, and local cooling were employed for all operations. Isolated AVR was performed in 3 patients in each group. In Group 1, the mean increase in diameter of the annulus was 4.82 mm, which resulted in a mean area increase of 169.91 mm2 (51.7%). Mean aortic cross-clamp times were 140.4 minutes and 93.5 minutes in Groups 1 and 2, respectively. There were 2 operative deaths in Group 1, and 1 operative and 1 late death in Group 2. Mean follow-up was 26.5 months for Group 1 and 43.4 months for Group 2. No thomboembolic or bleeding episodes have been recorded. Considerations and conclusions are offered from the study of this small series of patients.

  15. Application of Regent mechanical valve in patients with small aortic annulus: 3-year follow-up

    Directory of Open Access Journals (Sweden)

    Zhao Dong

    2012-09-01

    Full Text Available Abstract Background Aortic valve replacement (AVR with a small aortic annulus is always challenging for the cardiac surgeon. In this study, we sought to evaluate the midterm performance of implantation with a 17-mm or 19-mm St. Jude Medical Regent (SJM Regent mechanical valve in retrospective consecutive cohort of patients with small aortic annulus (diameter ≤ 19 mm. Methods From January 2008 to April 2011, 40 patients (31 female, mean age = 47.2 ± 5.8 years with small aortic annulus (≤19 mm in diameter underwent aortic valve replacement with a 17-mm or 19-mm St. Jude Medical Regent (SJM Regent mechanical valve. Preoperative mean body surface area, New York Heart Association class, and mean aortic annulus were 1.61 ± 0.26 m2, 3.2 ± 0.4, and 18 ± 1.4 mm respectively. Patients were divided into two groups, according to the implantation of 17 mm SJM Regent mechanical valve (group 1, n = 18 or 19 mm SJM Regent valve (group 2, n = 22. All patients underwent echocardiography examination preoperatively and at one year post-operation. Results There were no early deaths in either group. Follow-up time averaged 36 ± 17.6 months. The mean postoperative New York Heart Association class was 1.3 ± 0.6 (p 2/m2 to 69.8 ± 9.3%, 41.4 ± 8.3%, and 0.92 ± 0.10 cm2/m2 respectively (P 2, 46.1 ± 8.5 mmHg to 86.7 ± 18.2 g/m2 , 13.7 ± 5.2 mmHg respectively. In group 2, the LVEF, LVFS and EOAI increased from 45.9% ± 9.7%, 30.7% ± 8.0%, and 0.81 ± 0.09 cm2/m2 to 77.4% ± 9.7%, 44.5% ± 9.6%, and 1.27 ± 0.11 cm2/m2 respectively, while the LVMI, and the aortic transvalvular pressure gradient decreased from 118.3 ± 27.6 g/m2, 44.0 ± 6.7 mmHg to 80.1 ± 19.7 g/m2, 10.8 ± 4.1 mmHg as well. The prevalence of PPM was documented in 2 patients in Group 1. Conclusions Patients with small aortic annulus and body surface

  16. Three dimensional evaluation of the aortic annulus using multislice computer tomography: Are manufacturer's guidelines for sizing for percutaneous aortic valve replacement helpful?

    NARCIS (Netherlands)

    C.J. Schultz (Carl); A. Moelker (Adriaan); N. Piazza (Nicolo); A. Tzikas (Apostolos); A. Otten (Amber); R-J.M. Nuis (Rutger-Jan); L.A.E. Neefjes (Lisan); R.J.M. van Geuns (Robert Jan); P.J. de Feyter (Pim); G.P. Krestin (Gabriel); P.W.J.C. Serruys (Patrick); P.P.T. de Jaegere (Peter)

    2010-01-01

    textabstractAimsTo evaluate the effects of applying current sizing guidelines to different multislice computer tomography (MSCT) aortic annulus measurements on Corevalve (CRS) size selection.Methods and resultsMultislice computer tomography annulus diameters [minimum: Dmin; maximum: Dmax; mean: Dmea

  17. Evaluation of intervertebral disc regeneration with implantation of bone marrow mesenchymal stem cells (BMSCs) using quantitative T2 mapping: a study in rabbits.

    Science.gov (United States)

    Cai, Feng; Wu, Xiao-Tao; Xie, Xin-Hui; Wang, Feng; Hong, Xin; Zhuang, Su-Yang; Zhu, Lei; Rui, Yun-Feng; Shi, Rui

    2015-01-01

    The aim of the study was to investigate the curative effects of transplantation of bone marrow mesenchymal stem cells (BMSCs) on intervertebral disc regeneration and to investigate the feasibility of the quantitative T2 mapping method for evaluating repair of the nucleus pulposus after implantation of BMSCs. Forty-eight New Zealand white rabbits were used to establish the lumber disc degenerative model by stabbing the annulus fibrosus and then randomly divided into four groups, i.e. two weeks afterwards, BMSCs or phosphate-buffered saline (PBS) were transplanted into degenerative discs (BMSCs group and PBS group), while the operated rabbits without implantation of BMSCs or PBS served as the sham group and the rabbits without operation were used as the control group. At weeks two, six and ten after operation, the T2 values and disc height indices (DHI) were calculated by magnetic resonance imaging (MRI 3.0 T), and the gene expressions of type II collagen (COL2) and aggrecan (ACAN) in degenerative discs were evaluated by real-time reverse transcription polymerase chain reaction (RT-PCR). T2 values for the nucleus pulposus were correlated with ACAN or COL2 expression by regression analysis. Cell clusters, disorganised fibres, interlamellar glycosaminoglycan (GAG) matrix and vascularisation were observed in lumber degenerative discs. BMSCs could be found to survive in intervertebral discs and differentiate into nucleus pulposus-like cells expressing COL2 and ACAN. The gene expression of COL2 and ACAN increased during ten weeks after transplantation as well as the T2 signal intensity and T2 value. The DHI in the BMSCs group decreased more slowly than that in PBS and sham groups. The T2 value correlated significantly with the gene expression of ACAN and COL2 in the nucleus pulposus. Transplantation of BMSCs was able to promote the regeneration of degenerative discs. Quantitative and non-invasive T2 mapping could be used to evaluate the regeneration of the nucleus

  18. Analysis of optical vortices with suppressed sidelobes using modified Bessel-like function and trapezoid annulus modulation structures.

    Science.gov (United States)

    Guo, Jian; Wei, Zhongchao; Liu, Yuebo; Huang, Aili

    2015-02-01

    Two amplitude modulation methods, including modified Bessel-like function modulation structure and trapezoid annulus structure, for suppressing sidelobes of optical vortices are studied. In the former approach, we propose that the order of the Bessel-like function can be an additional parameter to modulate diffraction patterns of optical vortices motivated by the idea of conventional annulus structures. Furthermore, new Bessel-like modulation functions are introduced to solve the problem of low diffraction efficiency of the original one. Trapezoid annulus structure is proposed as a compromise structure between the modified Bessel-like modulation structure and the conventional annulus one, and has advantages of both. It is demonstrated that these two approaches can achieve high-quality optical vortices with suppressed sidelobes effectively, and the relative structures behave as more flexible and applicable structures for producing optical vortices with large coverage of topological charges, which suggests great potential in simplifying the structure designing procedure. These reliable and generalized structures for generating high-quality optical vortices will help to promote the development of future optical communication and optical manipulation significantly.

  19. Transesophageal echocardiography measurements of aortic annulus diameter using biplane mode in patients undergoing transcatheter aortic valve implantation

    Directory of Open Access Journals (Sweden)

    Shahgaldi Kambiz

    2013-01-01

    Full Text Available Abstract Background Aortic stenosis (AS is a relevant common valve disorder. Severe AS and symptoms and/or left ventricular dysfunction (EF Aim of the study is to assess the aortic annulus diameter in patients undergoing TAVI by biplane (BP mode using transesophageal echocardiography (TEE and compare it to two-dimensional (2D transthoracic echocardiography (TTE and 2DTEE using three-dimensional (3D TEE as reference method. Methods The study population consisted of 50 patients retrospectively (24 men and 26 women, mean age 85±8 years of age who all had undergone echocardiography examination prior to TAVI. Results The mean aortic annulus diameter was 20.4±2.2 mm with TTE, 22.3±2.5 mm with 2DTEE, 22.9±1.9 mm with BP-mode and 23.1±1.9 mm with 3DTEE. TTE underestimated the mean aortic annulus diameter in comparison to transesophageal imaging modalities (p Conclusion A multi-dimensional method is preferred to assess aortic annulus diameter in TAVI patients since there is risk of underestimation using single plane. Biplane mode is the method of choice in view of speedy post-processing with no need for expensive dedicated software. Lastly, single plane methods lead to misclassification of patients as unsuitable for TAVI. This may be of major clinical importance.

  20. Aortic valve replacement for aortic stenosis with a small aortic annulus in a patient having Werner's syndrome and liver cirrhosis.

    Science.gov (United States)

    Sogawa, M; Kasuya, S; Yamamoto, K; Koshika, M; Oguma, F; Hayashi, J

    2001-12-01

    Werner's syndrome is a rare genetic disease characterized by premature aging and scleroderma-like involvement of the skin. We report a case of aortic valve replacement for severely calcified aortic valve stenosis with a small annulus in a patient suffering from Werner's syndrome and liver cirrhosis

  1. Burn-out, Circumferential Film Flow Distribution and Pressure Drop for an Eccentric Annulus with Heated Rod

    DEFF Research Database (Denmark)

    Andersen, P. S.; Jensen, A.; Mannov, G.

    1974-01-01

    Measurements of (1) burn-out, (2) circumferential film flow distribution, and (3) pressure drop in a 17 × 27.2 × 3500 mm concentric and eccentric annulus geometry are presented. The eccentric displacement was varied between 0 and 3 mm. The working fluid was water. Burn-out curves at 70 bar...... flow variation on burn-out is discussed....

  2. Numerical simulation of solidification in a horizontal cylindrical annulus charged with an aqueous salt solution

    Science.gov (United States)

    Neilson, D. G.; Incropera, F. D.; Bennon, W. D.

    1990-01-01

    A computational study of solidification of a binary Na2CO3 solution in a horizontal cylindrical annulus is performed using a continuum formulation with a control-volume based, finite-difference scheme. The initial conditions were selected to facilitate the study of counter thermal and solutal convection, accompanied by extensive mushy region growth. Numerical results are compared with experimental data with mixed success. Qualitative agreement is obtained for the overall solidification process and associated physical phenomena. However, the plume thickness calculated for the solutally-driven convective upflow is substantially smaller than the observed value. Evolution of double-diffusive layers is predicted, but over a time scale much smaller than that observed experimentally. Good agreement is obtained between predicted and measured results for solid growth, but the mushy region thickness is significantly overpredicted.

  3. Effects of nanoparticles on the peristaltic motion of tangent hyperbolic fluid model in an annulus

    Directory of Open Access Journals (Sweden)

    S. Nadeem

    2015-12-01

    Full Text Available In the present article, effects of nanoparticles on the peristaltic flow of tangent hyperbolic fluid in an annulus are described. The two-dimensional equations of tangent hyperbolic fluid are solved by using the assumptions of low Reynolds number and long wavelength. Analytical solution is obtained with the help of homotopy perturbation and Adomian decomposition method for velocity, temperature and nanoparticles concentration. Solutions are discussed through graphs. Solutions for pressure rise, temperature, nanoparticles concentration, pressure gradient and streamlines are plotted for various emerging parameters. It is found that the temperature profile increases with increase in Brownian motion and thermophoresis parameter. It is also found that the size of the trapped bolus in triangular wave is smaller as compared to other waves. Further, the comparison of both analytical solutions is presented.

  4. Experimental study on convective boiling heat transfer in narrow-gap annulus tubes

    Institute of Scientific and Technical Information of China (English)

    LI Bin; ZHAO Jian-Fu; ZHOU Fang-De; TANG Ze-Mei; HU Wen-Rui

    2004-01-01

    Since convective boiling or highly subcooled single-phase forced convection in micro-channels is an effective cooling mechanism with a wide range of applications, more experimental and theoretical studies are required to explain and verify the forced convection heat transfer phenomenon in narrow channels. In this experimental study, we model the convective boiling behavior of water with low latent heat substance Freon 113 (R-113), with the purpose of saving power consumption and visualizing experiments. Both heat transfer and pressure drop characteristics were measured in subcooled and saturated concentric narrow gap forced convection boiling. Data were obtained to qualitatively identify the effects of gap size, pressure, flow rate and wall superheat on boiling regimes and the transition between various regimes. Some significant differences from unconfined forced convection boiling were found,and also, the flow patterns in narrow vertical annulus tubes have been studied quantitatively.

  5. Curvature effects on axisymmetric instability of conduction regime in a tall air-filled annulus

    Science.gov (United States)

    Pécheux, J.; Le Quéré, P.; Abcha, F.

    1994-10-01

    This paper numerically studies curvature effects on the instability of the conduction regime of natural convection in a tall air-filled differentially heated annulus of vertical aspect ratio 16 by integrating the two-dimensional axisymmetric Navier-Stokes equations in the Boussinesq approximation. The numerical algorithm combines a pseudospectral Chebyshev space discretization with a second-order time-stepping scheme. It is shown that, in contrast with linear stability analysis of the conduction solution, the time-periodic cross-roll instability does not take place in finite aspect ratio cavities for small values of the radius ratio. For all values of the radius ratio transition to unsteadiness occurs through supercritical Hopf bifurcations. Extensive computations show very complex behaviors of the unsteady solutions depending on the radius ratio. The nature of the reverse transition to steady state that occurs for increasing value of the Rayleigh number is also found to depend strongly on the value of the radius ratio.

  6. Hydromagnetic convection in a rotating annulus with an azimuthal magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Kurt, E.; Busse, F.H.; Pesch, W. [University of Bayreuth, Institute of Physics, Bayreuth (Germany)

    2004-11-01

    The problem of convection induced by radial buoyancy in an electrically conducting fluid contained by a rotating cylindrical annulus (angular frequency, {omega}) in the presence of a homogeneous magnetic field (B) in the azimuthal direction is considered. The small gap approximation is used together with rigid cylindrical boundaries. The onset of convection occurs in the form of axial, axisymmetric or oblique rolls. The angle {psi} between the roll axis and the axis of rotation depends of the ratio between the Chandrasekhar number, Q{proportional_to}B{sup 2}, and the Coriolis number, {tau}{proportional_to}{omega}. Fully three-dimensional numerical simulations as well as Galerkin representations for roll patterns including the subsequent stability analysis are used in the theoretical investigation. At finite amplitudes, secondary transitions to 3D-hexarolls and to spatio-temporal chaos are found. Overlapping regions of pattern stability exist such that the asymptotically realized state may depend on the initial conditions. (orig.)

  7. Mixed Convection Opposing Flow in a Vertical Porous Annulus-Two Temperature Model

    Science.gov (United States)

    Al-Rashed, Abdullah A. AA; J, Salman Ahmed N.; Khaleed, H. M. T.; Yunus Khan, T. M.; NazimAhamed, K. S.

    2016-09-01

    The opposing flow in a porous medium refers to a condition when the forcing velocity flows in opposite direction to thermal buoyancy obstructing the buoyant force. The present research refers to the effect of opposing flow in a vertical porous annulus embedded with fluid saturated porous medium. The thermal non-equilibrium approach with Darcy modal is considered. The boundary conditions are such that the inner radius is heated with constant temperature Tw the outer radius is maintained at constant temperature Tc. The coupled nonlinear partial differential equations such as momentum equation, energy equation for fluid and energy equation for solid are solved using the finite element method. The opposing flow variation of average Nusselt number with respect to radius ratio Rr, Aspect ratioAr and Radiation parameter Rd for different values of Peclet number Pe are investigated. It is found that the flow behavior is quite different from that of aiding flow.

  8. A linear analysis of the transition curve for the baroclinic annulus

    Science.gov (United States)

    Miller, T. L.; Gall, R. L.

    1983-01-01

    A primitive equation linear model is shown to be capable of quantitatively predicting the neutral curve for a baroclinic annulus. Flows unstable to small nonaxisymmetric perturbations are assumed to lie on the nonaxisymmetric side of a transition curve, while the stable flows are on the axisymmetric side. The stability in the presence of perturbations is tested with linearized hydrostatic primitive equations. Attention is given to the fastest growing eigenmodes, demonstrating that the linear and nonlinear wave have similar structures at a particular point in the nonaxisymmetric regime. All the waves are similar to the Eddy wave except at the extreme to the transition curve, where the waves maintain little structure with height. The eddy kinetic energy is baroclinic with a potential energy suppresed by the large static stability of the basic state. Eddy dissipation is noted to be significant near all boundaries.

  9. Double-diffusive convection in a rotating cylindrical annulus with conical caps

    CERN Document Server

    Simitev, R D

    2011-01-01

    Double-diffusive convection driven by both thermal and compositional buoyancy in a rotating cylindrical annulus with conical caps is considered with the aim to establish whether a small fraction of compositional buoyancy added to the thermal buoyancy (or vice versa) can significantly reduce the critical Rayleigh number and amplify convection in planetary cores. It is shown that the neutral surface describing the onset of convection in the double-buoyancy case is essentially different from that of the well-studied purely thermal case, and does indeed allow the possibility of low-Rayleigh number convection. In particular, isolated islands of instability are formed by an additional "double-diffusive" eigenmode in certain regions of the parameter space. However, the amplitude of such low-Rayleigh number convection is relatively weak. At similar flow amplitudes purely compositional and double-diffusive cases are characterized by a stronger time dependence compared to purely thermal cases, and by a prograde mean zo...

  10. Automatic mitral annulus tracking in volumetric ultrasound using non-rigid image registration.

    Science.gov (United States)

    De Veene, Henri; Bertrand, Philippe B; Popovic, Natasa; Vandervoort, Pieter M; Claus, Piet; De Beule, Matthieu; Heyde, Brecht

    2015-01-01

    Analysis of mitral annular dynamics plays an important role in the diagnosis and selection of optimal valve repair strategies, but remains cumbersome and time-consuming if performed manually. In this paper we propose non-rigid image registration to automatically track the annulus in 3D ultrasound images for both normal and pathological valves, and compare the performance against manual tracing. Relevant clinical properties such as annular area, circumference and excursion could be extracted reliably by the tracking algorithm. The root-mean-square error, calculated as the difference between the manually traced landmarks (18 in total) and the automatic tracking, was 1.96 ± 0.46 mm over 10 valves (5 healthy and 5 diseased) which is within the clinically acceptable error range.

  11. A numerical study of entrance region in a curved annulus with an inward and outward eccentricity

    Directory of Open Access Journals (Sweden)

    M.R.H. Nobari

    2016-09-01

    Full Text Available In this article, developing incompressible fluid flow in a curved annulus with inward and outward eccentricities is studied numerically. To do so, a second order finite difference method based on the projection algorithm is employed to solve the governing equations written in a general bipolar–toroidal coordinate system using a three-dimensional staggered uniform grid. The effects of the governing dimensionless parameters such as the Dean number, Reynolds number, curvature ratio, aspect ratio, and eccentricity on the flow field pattern and friction factor are studied in the entrance region. The numerical results obtained indicate that the outward eccentricity significantly deforms the secondary flows and axial velocity profiles. Furthermore, as the eccentricity increases, the friction factor decreases due to the reduction of secondary flow intensity.

  12. Risk of Cerebral Embolization with Caseous Calcification of the Mitral Annulus: Review Article

    Science.gov (United States)

    Dietl, Charles A.; Hawthorn, Christopher M.; Raizada, Veena

    2016-01-01

    Background: Caseous calcification of the mitral annulus (CCMA) is believed to have a benign prognosis. Several authors have recommended conservative management in asymptomatic patients. However, the prevalence of cerebrovascular events (CVE) in patients with CCMA has never been evaluated before. The aims of this study are to investigate whether patients with CCMA are at increased risk of cerebral embolization, and to determine whether elective surgical resection of CCMA should be considered to prevent a cardioembolic stroke. Methods: A comprehensive literature search was obtained from MEDLINE via PubMed.gov, ScienceDirect.com, and Google Scholar using the following search queries: caseous calcification of the mitral annulus, intracardiac pseudotumor, mitral annular calcification, and cardioembolic stroke. Results: From our initial search that yielded 1,502 articles, we identified a total of 130 patients with CCMA reported in 86 publications. Literature review revealed that the prevalence of CVE associated with CCMA is 19.2% (25 of 130) which is significantly higher than the prevalence of CVE reported with mitral annular calcification (MAC), 11.8% (214 of 1818) (range 4.8% to 24.1%) (P = 0.01796) (odds ratio = 1.78; 0.95 confidence interval = 1.1278 – 2.8239). Only four of 25 (16.0%) patients with CCMA who suffered a CVE had history of atrial fibrillation (AF). Conclusion: Based on our review, it would be reasonable to consider elective surgical resection of CCMA in asymptomatic patients who are good surgical candidates, because patients with CCMA may be at increased risk of embolic strokes, which are unrelated to AF. PMID:27990181

  13. Association of mitral annulus calcification, aortic valve calcification with carotid intima media thickness

    Directory of Open Access Journals (Sweden)

    Scuteri Angelo

    2004-10-01

    Full Text Available Abstract Background Mitral annular calcification (MAC and aortic annular calcification (AVC may represent a manifestation of generalized atherosclerosis in the elederly. Alterations in vascular structure, as indexed by the intima media thickness (IMT, are also recognized as independent predictors of adverse cardiovascular outcomes. Aim To examine the relationship between the degree of calcification at mitral and/or aortic valve annulus and large artery structure (thickness. Methods We evaluated 102 consecutive patients who underwent transthoracic echocardiography and carotid artery echoDoppler for various indications; variables measured were: systemic blood pressure (BP, pulse pressure (PP=SBP-DBP, body mass index (BMI, fasting glucose, total, HDL, LDL chlolesterol, triglycerides, cIMT. The patients were divided according to a grading of valvular/annular lesions independent scores based on acoustic densitometry: 1 = annular/valvular sclerosis/calcification absence; 2 = annular/valvular sclerosis; 3 = annular calcification; 4 = annular-valvular calcification; 5 = valvular calcification with no recognition of the leaflets. Results Patient score was the highest observed for either valvular/annulus. Mean cIMT increased linearly with increasing valvular calcification score, ranging from 3.9 ± 0.48 mm in controls to 12.9 ± 1.8 mm in those subjects scored 5 (p 0.0001. Conclusion MAC and AVC score can identify subgroups of patients with different cIMT values which indicate different incidence and prevalence of systemic artery diseases. This data may confirm MAC-AVC as a useful important diagnostic parameter of systemic atherosclerotic disease.

  14. Pulmonary annulus preservation lowers the risk of late postoperative pulmonary valve implantation after the repair of tetralogy of Fallot.

    Science.gov (United States)

    Kim, Gwan Sic; Han, Seungbong; Yun, Tae-Jin

    2015-02-01

    The long-term benefits of pulmonary annulus preservation in tetralogy of Fallot (ToF) repair in patients with a marginally small pulmonary annulus are controversial. We sought to determine whether pulmonary annulus preservation (AP) is superior to transannular patching (TAP) in lowering the risk of pulmonary valve implantation (PVI) long after the repair of ToF. Of the 255 patients who underwent total correction of ToF during infancy between January 1989 and December 2005, 114 patients (AP group = 57, TAP group = 57) were selected by propensity score matching for various preoperative variables, such as age and body weight at operation, sex, pulmonary artery size, pre-repair palliation, anatomical types of ventricular septal defect, and Z-score of pulmonary valve annulus diameter (PVA-Z). The PVA-Z of the AP and TAP groups were -2.3 ± 1.3 and -2.1 ± 1.3, respectively (p = 0.547). The time to PVI was compared between the two groups. The median follow-up duration was 146 months (AP group: 141 months, TAP group: 147 months; p = 0.191). During the follow-up periods, there were 12 reoperations for the relief of right ventricular outflow tract obstruction (RVOTO), eight PVIs, and three late deaths. While freedom from reoperation for RVOTO was comparable between the two groups (p = 0.182), freedom from PVI at postoperative 15 years was significantly lower in the TAP group than in the AP group (74 and 100 %, p = 0.015). In repairing ToF with marginally small pulmonary valve annulus, AP is associated with a lower risk of late postoperative PVI.

  15. A finite volume approach to the problem of heat transfer in axisymmetric annulus geometry with internal heating element using local analytical solution techniques

    Energy Technology Data Exchange (ETDEWEB)

    Salama, A. [Atomic Energy Authority (AEA), Cairo (Egypt). Nuclear Research Center

    2014-11-15

    In this paper we implement the local analytical solution technique to the problem of heat transfer in axisymmetric annulus geometry with internal heating element. This method has shown to be very accurate in estimating the temperature field for axisymmetric problems even for coarse mesh. It is shown that this method reduces to the analytical solution for unidirectional heat transfer in the radial direction in homogeneous media. The technique is based on finding an analytical expression for the temperature field in the radial direction within each grid cell. This means that the temperature field in each cell is allowed to change in a nonlinear fashion along the radial direction. We compare this technique with the traditional finite volume technique and show that; with only few cells in the radial direction, this technique arrives at the mesh-independent solution quite accurately whereas it required denser mesh to arrive closer to this solution using traditional techniques. This method is proposed to the 1D codes that are currently being used to simulate thermalhydraulic characteristics of reactor systems. Furthermore, we also implement the experimental temperature field algorithm in which the governing equations are approximated for each cell as it would without extra manipulation to the governing equations. This technique is very simple and separates the physics from the solving part.

  16. Overlapping of mononuclear cells derived from bone marrow in rats' intervertebral discs: an in vitro study Sobreposição de células mononucleares provenientes da medula óssea em disco intervertebral de ratos: estudo in vitro

    Directory of Open Access Journals (Sweden)

    Erica Batista Fontes

    2010-04-01

    Full Text Available In this study, bone marrow mononuclear cells (BM-MNC derived from rats were used in order to promote intervertebral disc regeneration. These cells were isolated after centrifugation in a Ficoll-Paque™ PLUS density gradient and then placed in plastic dishes to proliferate during a period of 14 days. The BM-MNCs were previously labeled with the fluorescent membrane marker Chloromethyl-benzamidodialkylcarbocyanine (CM-DIL, and thereafter were implanted in rats' intervertebral discs explants as an in vitro experimental model. Daily analyses of the cells under a fluorescence microscope revealed morphological changes, which assumed a thin and elongated shape similar to cells that originally form the annulus fibroses. Histopathological analysis demonstrated the presence of mononuclear cells interspersed within collagen fibers. The presence of viable cells, in which were found morphological changes and their disposal in the same pattern of the layers that originate the annulus fibrosus, is an indicator that they engrafted and proliferated on the intervertebral disc. Therefore, morphological changes presented by these cells indicate that they presented mesenchymal stem-like cell characteristics.Neste trabalho, foram utilizadas células mononucleares provenientes da medula óssea (MO de ratos para implantação em discos intervertebrais, a fim de estudar a sua participação em possível regeneração tecidual. Essas células foram obtidas por centrifugação, em gradiente de Ficoll-Paque™ PLUS, e cultivadas em frascos apropriados, por um período de 14 dias. Em etapa posterior, foram submetidas à marcação celular, em que foi utilizado o marcador citoplasmático CM-Dil, seguida de implantação em discos intervertebrais de ratos, em um sistema de cultivo in vitro. Foram feitas avaliações diárias dos discos com utilização de um microscópio de fluorescência, sendo constatadas alterações morfológicas com um formato alongado semelhante a c

  17. Characteristics of turbulent heat transfer in an annulus at supercritical pressure

    Science.gov (United States)

    Peeters, J. W. R.; Pecnik, R.; Rohde, M.; van der Hagen, T. H. J. J.; Boersma, B. J.

    2017-02-01

    Heat transfer to fluids at supercritical pressure is different from heat transfer at lower pressures due to strong variations of the thermophysical properties with the temperature. We present and analyze results of direct numerical simulations of heat transfer to turbulent CO2 at 8 MPa in an annulus. Periodic streamwise conditions are imposed so that mean streamwise acceleration due to variations in the density does not occur. The inner wall of the annulus is kept at a temperature of 323 K, while the outer wall is kept at a temperature of 303 K. The pseudocritical temperature Tp c=307.7 K, which is the temperature where the thermophysical properties vary the most, can be found close to the inner wall. This work is a continuation of an earlier study, in which turbulence attenuation due to the variable thermophysical properties of a fluid at supercritical pressure was studied. In the current work, the direct effects of variations in the specific heat capacity, thermal diffusivity, density, and the molecular Prandtl number on heat transfer are investigated using different techniques. Variations in the specific heat capacity cause significant differences between the mean nondimensionalized temperature and enthalpy profiles. Compared to the enthalpy fluctuations, temperature fluctuations are enhanced in regions with low specific heat capacity and diminished in regions with a large specific heat capacity. The thermal diffusivity causes local changes to the mean enthalpy gradient, which in turn affects molecular conduction of thermal energy. The turbulent heat flux is directly affected by the density, but it is also affected by the mean molecular Prandtl number and attenuated or enhanced turbulent motions. In general, enthalpy fluctuations are enhanced in regions with a large mean molecular Prandtl number, which enhances the turbulent heat flux. While analyzing the Nusselt numbers under different conditions it is found that heat transfer deterioration or enhancement can

  18. Multivariate statistical data analysis methods for detecting baroclinic wave interactions in the thermally driven rotating annulus

    Science.gov (United States)

    von Larcher, Thomas; Harlander, Uwe; Alexandrov, Kiril; Wang, Yongtai

    2010-05-01

    Experiments on baroclinic wave instabilities in a rotating cylindrical gap have been long performed, e.g., to unhide regular waves of different zonal wave number, to better understand the transition to the quasi-chaotic regime, and to reveal the underlying dynamical processes of complex wave flows. We present the application of appropriate multivariate data analysis methods on time series data sets acquired by the use of non-intrusive measurement techniques of a quite different nature. While the high accurate Laser-Doppler-Velocimetry (LDV ) is used for measurements of the radial velocity component at equidistant azimuthal positions, a high sensitive thermographic camera measures the surface temperature field. The measurements are performed at particular parameter points, where our former studies show that kinds of complex wave patterns occur [1, 2]. Obviously, the temperature data set has much more information content as the velocity data set due to the particular measurement techniques. Both sets of time series data are analyzed by using multivariate statistical techniques. While the LDV data sets are studied by applying the Multi-Channel Singular Spectrum Analysis (M - SSA), the temperature data sets are analyzed by applying the Empirical Orthogonal Functions (EOF ). Our goal is (a) to verify the results yielded with the analysis of the velocity data and (b) to compare the data analysis methods. Therefor, the temperature data are processed in a way to become comparable to the LDV data, i.e. reducing the size of the data set in such a manner that the temperature measurements would imaginary be performed at equidistant azimuthal positions only. This approach initially results in a great loss of information. But applying the M - SSA to the reduced temperature data sets enable us to compare the methods. [1] Th. von Larcher and C. Egbers, Experiments on transitions of baroclinic waves in a differentially heated rotating annulus, Nonlinear Processes in Geophysics

  19. Flow regime development analysis in adiabatic upward two-phase flow in a vertical annulus

    Energy Technology Data Exchange (ETDEWEB)

    Julia, J. Enrique [Departamento de Ingenieria Mecanica y Construccion, Universitat Jaume I, Campus de Riu Sec, Castellon 12071 (Spain); Ozar, Basar [School of Nuclear Engineering, Purdue University, 400 Central Dr., West Lafayette, IN 47907-2017 (United States); Jeong, Jae-Jun [Korea Atomic Energy Research Institute, 150 Dukjin, Yuseong, Daejeon 305-353 (Korea, Republic of); Hibiki, Takashi [School of Nuclear Engineering, Purdue University, 400 Central Dr., West Lafayette, IN 47907-2017 (United States); Ishii, Mamoru, E-mail: ishii@purdue.ed [School of Nuclear Engineering, Purdue University, 400 Central Dr., West Lafayette, IN 47907-2017 (United States)

    2011-02-15

    In this work radial and axial flow regime development in adiabatic upward air-water two-phase flow in a vertical annulus has been investigated. Local flow regimes have been identified using conductivity probes and neural networks techniques. The inner and outer diameters of the annulus are 19.1 mm and 38.1 mm, respectively. The equivalent hydraulic diameter of the flow channel, D{sub H}, is 19.0 mm and the total length is 4.37 m. The flow regime map includes 1080 local flow regimes identifications in 72 flow conditions within a range of 0.01 m/s < < 30 m/s and 0.2 m/s < < 3.5 m/s where and are, respectively, superficial gas and liquid velocities. The local flow regime has been classified into four categories: bubbly, cap-slug, churn-turbulent and annular flows. In order to study the radial and axial development of flow regime the measurements have been performed at five radial locations. The three axial positions correspond to z/D{sub H} = 52, 149 and 230, where z represents the axial position. The flow regime indicator has been chosen as some statistical parameters of local bubble chord length distributions and self-organized neural networks have been used as mapping system. This information has been also used to compare the results given by the existing flow regime transition models. The local flow regime is characterized basically by the void fraction and bubble chord length. The radial development of flow regime shows partial and complete local flow regime combinations. The radial development is controlled by axial location and superficial liquid velocity. The radial flow regime transition is always initiated in the center of the flow channel and it is propagated towards the channel boundaries. The axial development of flow regime is observed in all the flow maps and it is governed by superficial liquid velocity and radial location. The prediction results of the models are compared for each flow regime transition.

  20. [Dehiscence of the Pericardial Patch, after Surgical Treatment of Active Infective Aortic Valve Endocarditis with Reconstruction of the Aortic Annulus Using a Glutaraldehyde-treated Autologous Pericardium].

    Science.gov (United States)

    Yoshida, Kazufumi; Fukunaga, Naoto; Koizumi, Shigeki; Nishiya, Kenta; Matsuda, Yasuhiro; Ishigami, Masanosuke; Nagasawa, Atsushi; Sakata, Ryuzo; Koyama, Tadaaki

    2017-03-01

    A 50-year-old man was admitted with fever and chill sensation 6 months ago. Transthoracic echocardiography (TTE) showed left and right coronary cusp prolapses and a thickened tissue of the aortic curtain. Congestive heart failure due to active infective aortic valve endocarditis was diagnosed, and he underwent aortic valve replacement. The aortic annulus was reconstructed using a glutaraldehydetreated autologous pericardium. Six months after surgery, TTE showed severe aortic regurgitation and saccular change in the aortic annulus. Transesophageal echocargiography showed some echo free space from left to noncoronary cusp and abnormal movement of the prosthetic valve annulus. Intraoperative examination showed dehiscence of the pericardial patch from the aortic wall, but no finding of infection. Aortic valve rereplacement was performed with reconstruction of the aortic annulus using a bovine pericardium. To prevent the dehiscence of the pericardial patch from the aortic wall, sutures fixing the prosthetic valve were passed from outside of the aortic wall.

  1. INVESTIGATION ON THE FLOW STABILITY OF NEWTONIAN FLUID IN ECCENTRIC ANNULUS VIA THE AXIAL RECIPROCATION OF THE INNER TUBE

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The governing equation, together with the formulas of the averaged flux and the stability parameter for Newtonian fluid flowing in eccentric annulus via the axial reciprocation of the inner tube was established in the bipolar coordinate system. Numerical calculation was conducted for the measurement of water flow using the formulas above, of which the results agree well with the experimental data. It is shown that the flow instability can be induced by the increase of the stroke, the frequency, and the eccentricity of annulus, making the sucker rod more susceptible to partial abrasion. Some protecting methods, including adding centralizers, adjusting the stroke and frequency, are proposed to protect the sucker rod from the partial abrasion, and satisfactory results have been achieved in the oilfields.

  2. Recurrent discrete subaortic stenosis and small aortic annulus successfully repaired by the Konno procedure in a young woman.

    Science.gov (United States)

    Kashima, Ichiro; Ueda, Toshihiko; Katogi, Toshiyuki; Taguchi, Shinichi; Inoue, Yoshito; Koizumi, Kiyoshi

    2006-10-01

    A 24-year-old woman who had undergone excision of the membrane for discrete subaortic stenosis when 6 years old displayed recurrent subaortic stenosis and had a small aortic annulus, with a peak pressure gradient of 60mmHg. We chose to perform the Konno operation with a mechanical valve. This released the left ventricular outflow tract obstruction adequately, and she recovered uneventfully with New York Heart Association functional class I. In our experience, an aggressive strategy such as myectomy is an appropriate initial procedure for preventing recurrence when the geometry of the problem may lead to recurrence in the left ventricular outflow tract. The Konno operation is a good option for recurrent subaortic stenosis with small aortic annulus.

  3. Experimental research on heat transfer to liquid sodium and its incipient boiling wall superheat in an annulus

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Liquid sodium is mainly used as a cooling fluid in the liquid metal fast breeder reactor (LMFBR), whose heat transfer, whether convective heat transfer or boiling heat transfer, is different from that of water. So it is important for both normal and accidental operations of LMFBR to perform experimental research on heat transfer to liquid sodium and its boiling heat transfer. This study deals with heat transfer with high temperature (300-700℃) and low Pe number (20~70) and heat transfer with low temperature (250~270℃) and high Pe number (125~860), and its incipient boiling wall superheat in an annulus. Research on heat transfer involves theoretical research and experiments on heat transfer to liquid sodium. It also focuses on the theoretical analysis and experimental research on its incipient boiling wall superheat at positive pressure in an annulus. Semiempirical correlations were obtained and they were well coincident with the experimental data.

  4. Cardiovascular magnetic resonance as a reliable alternative to cardiovascular computed tomography and transesophageal echocardiography for aortic annulus valve sizing.

    Science.gov (United States)

    Faletti, Riccardo; Gatti, Marco; Salizzoni, Stefano; Bergamasco, Laura; Bonamini, Rodolfo; Garabello, Domenica; Marra, Walter Grosso; La Torre, Michele; Morello, Mara; Veglia, Simona; Fonio, Paolo; Rinaldi, Mauro

    2016-08-01

    To assess the accuracy and reproducibly of cardiovascular magnetic resonance (CMR) in the measurement of the aortic annulus and in process of valve sizing as compared to intra-operative sizing, cardiovascular computed tomography (CCT) and transesophageal echocardiography (TEE). Retrospective study on 42 patients who underwent aortic valve replacement from September 2010 to September 2015, with available records of pre surgery annulus assessment by CMR, CCT and TEE and of peri-operative assessment. In CCT and CMR, the annular plane was considered a virtual ring formed by the lowest hinge points of the valvular attachments to the aorta. In TEE the annulus was measured at the base of leaflet insertion in the mid-esophageal long-axis view using the X-plane technique. Two double-blinded operators performed the assessments for each imaging technique. Intra-operative evaluation was performed using Hegar dilators. Continuous variables were studied with within-subject ANOVA, Bland-Altman (BA) plots, Wilcoxon's and Friedman's tests; trends were explored with scatter plots. Categorical variables were studied with Fisher's exact test. The intra- and inter-operator reliability was satisfying. There were no significant differences between the annulus dimensions measured by CMR and either one of the three references. Valve sizing for CoreValve by CMR had the same good agreement with CCT and TEE, with a 78 % match rate; for SAPIEN XT the agreement was slightly better (82 %) for CCT than for TEE (66 %). MR performs well when compared to the surgical reference of intra-operative sizing and stands up to the level of the most used imaging references (CCT and TEE).

  5. The Development of a Gas-Liquid Two-Phase Flow Sensor Applicable to CBM Wellbore Annulus.

    Science.gov (United States)

    Wu, Chuan; Wen, Guojun; Han, Lei; Wu, Xiaoming

    2016-11-18

    The measurement of wellbore annulus gas-liquid two-phase flow in CBM (coalbed methane) wells is of great significance for reasonably developing gas drainage and extraction processes, estimating CBM output, judging the operating conditions of CBM wells and analyzing stratum conditions. Hence, a specially designed sensor is urgently needed for real-time measurement of gas-liquid two-phase flow in CBM wellbore annulus. Existing flow sensors fail to meet the requirements of the operating conditions of CBM wellbore annulus due to such factors as an inapplicable measurement principle, larger size, poor sealability, high installation accuracy, and higher requirements for fluid media. Therefore, based on the principle of a target flowmeter, this paper designs a new two-phase flow sensor that can identify and automatically calibrate different flow patterns of two-phase flows. Upon the successful development of the new flow sensor, lab and field tests were carried out, and the results show that the newly designed sensor, with a measurement accuracy of ±2.5%, can adapt to the operating conditions of CBM wells and is reliable for long-term work.

  6. Structure of recombinant capsids formed by the beta-annulus deletion mutant -- rCP (Delta48-59) of Sesbania mosaic virus.

    Science.gov (United States)

    Pappachan, Anju; Subashchandrabose, Chinnathambi; Satheshkumar, P S; Savithri, H S; Murthy, M R N

    2008-05-25

    A unique feature of several T=3 icosahedral viruses is the presence of a structure called the beta-annulus formed by extensive hydrogen bonding between protein subunits related by icosahedral three-fold axis of symmetry. This unique structure has been suggested as a molecular switch that determines the T=3 capsid assembly. In order to examine the importance of the beta-annulus, a deletion mutant of Sesbania mosaic virus coat protein in which residues 48-59 involved in the formation of the beta-annulus were deleted retaining the rest of the residues in the amino terminal segment (rCP (Delta48-59)) was constructed. When expressed in Escherichia coli, the mutant protein assembled into virus like particles of sizes close to that of the wild type virus particles. The purified capsids were crystallized and their three dimensional structure was determined at 3.6 A resolution by X-ray crystallography. The mutant capsid structure closely resembled that of the native virus particles. However, surprisingly, the structure revealed that the assembly of the particles has proceeded without the formation of the beta-annulus. Therefore, the beta-annulus is not essential for T=3 capsid assembly as speculated earlier and may be formed as a consequence of the particle assembly. This is the first structural demonstration that the virus particle morphology with and without the beta-annulus could be closely similar.

  7. CFD Calculation of Internal Natural Convection in the Annulus between Horizontal Concentric Cylinders

    Energy Technology Data Exchange (ETDEWEB)

    N.D. Francis, Jr; M.T. Itamura; S.W. Webb; D.L. James

    2002-10-01

    The objective of this heat transfer and fluid flow study is to assess the ability of a computational fluid dynamics (CFD) code to reproduce the experimental results, numerical simulation results, and heat transfer correlation equations developed in the literature for natural convection heat transfer within the annulus of horizontal concentric cylinders. In the literature, a variety of heat transfer expressions have been developed to compute average equivalent thermal conductivities. However, the expressions have been primarily developed for very small inner and outer cylinder radii and gap-widths. In this comparative study, interest is primarily focused on large gap widths (on the order of half meter or greater) and large radius ratios. From the steady-state CFD analysis it is found that the concentric cylinder models for the larger geometries compare favorably to the results of the Kuehn and Goldstein correlations in the Rayleigh number range of about 10{sup 5} to 10{sup 8} (a range that encompasses the laminar to turbulent transition). For Rayleigh numbers greater than 10{sup 8}, both numerical simulations and experimental data (from the literature) are consistent and result in slightly lower equivalent thermal conductivities than those obtained from the Kuehn and Goldstein correlations.

  8. Forced Convective Condensation of Nonazeotropic Refrigerant Mixtures in Horizontal Annulus with Petal Shaped Fin Tubes

    Institute of Scientific and Technical Information of China (English)

    WangShiping; ZhouXinqiu; 等

    1995-01-01

    In this paper,condensation performance in horizontal annulus was compared with a smooth tube,one Saw-Tooth Finned tube(STF tube),four Petal Shaped Fin tubes(PF tubes),using R113,R11 and their mixtures(vapor molar fractions of R11 at the test section inlet were 0.384,0.588and 0.809) as working fluid.The mass flux at the test section ranged from 15-220/m2s。Camera and video camera were used to shoot the flow pattern and condensation phenomena.The condensation transfer coefficient(hc) of mixtures were considerably lower than those of pure fluid,and did not change linearly with composition.The maximum degradation of measured hc from the ideal value were 23% for the smooth tube,65%for STF tube,67% for PF tubes,which occurred in the composition range of 0.4-0.6 vapor molar fraction of R11.For the condensation of mixture,R11 molar fraction from 38%to 81%,the PF tubes had the highest value of hc.which were 10-25% higher than those of STF tubes,and 480-580% higher than that of smooth tube,because the petal shaped fins of PF tubes could promote strong turbulence in the two phase flow,and reduce the mass transfer resistance.

  9. Identification of Mitral Annulus Hinge Point Based on Local Context Feature and Additive SVM Classifier

    Directory of Open Access Journals (Sweden)

    Jianming Zhang

    2015-01-01

    Full Text Available The position of the hinge point of mitral annulus (MA is important for segmentation, modeling and multimodalities registration of cardiac structures. The main difficulties in identifying the hinge point of MA are the inherent noisy, low resolution of echocardiography, and so on. This work aims to automatically detect the hinge point of MA by combining local context feature with additive support vector machines (SVM classifier. The innovations are as follows: (1 designing a local context feature for MA in cardiac ultrasound image; (2 applying the additive kernel SVM classifier to identify the candidates of the hinge point of MA; (3 designing a weighted density field of candidates which represents the blocks of candidates; and (4 estimating an adaptive threshold on the weighted density field to get the position of the hinge point of MA and exclude the error from SVM classifier. The proposed algorithm is tested on echocardiographic four-chamber image sequence of 10 pediatric patients. Compared with the manual selected hinge points of MA which are selected by professional doctors, the mean error is in 0.96 ± 1.04 mm. Additive SVM classifier can fast and accurately identify the MA hinge point.

  10. Identification of Mitral Annulus Hinge Point Based on Local Context Feature and Additive SVM Classifier.

    Science.gov (United States)

    Zhang, Jianming; Liu, Yangchun; Xu, Wei

    2015-01-01

    The position of the hinge point of mitral annulus (MA) is important for segmentation, modeling and multimodalities registration of cardiac structures. The main difficulties in identifying the hinge point of MA are the inherent noisy, low resolution of echocardiography, and so on. This work aims to automatically detect the hinge point of MA by combining local context feature with additive support vector machines (SVM) classifier. The innovations are as follows: (1) designing a local context feature for MA in cardiac ultrasound image; (2) applying the additive kernel SVM classifier to identify the candidates of the hinge point of MA; (3) designing a weighted density field of candidates which represents the blocks of candidates; and (4) estimating an adaptive threshold on the weighted density field to get the position of the hinge point of MA and exclude the error from SVM classifier. The proposed algorithm is tested on echocardiographic four-chamber image sequence of 10 pediatric patients. Compared with the manual selected hinge points of MA which are selected by professional doctors, the mean error is in 0.96 ± 1.04 mm. Additive SVM classifier can fast and accurately identify the MA hinge point.

  11. Age estimation for shovelnose sturgeon: A cautionary note based on annulus formation in pectoral fin rays

    Science.gov (United States)

    Whiteman, K.W.; Travnichek, V.H.; Wildhaber, M.L.; DeLonay, A.; Papoulias, D.; Tillett, D.

    2004-01-01

    Numerous studies have examined the age and growth of shovelnose sturgeon Scaphirhynchus platorynchus, but only one study attempted to validate age estimation techniques. Therefore, our objective was to use marginal increment analysis to validate annulus formation in pectoral fin rays of shovelnose sturgeon collected from the Missouri River. We also compared the precision of age estimates between two different readers. Marginal increment distance indicated that for most of the populations an opaque band was laid down in pectoral fin rays during the summer. However, opaque bands were formed throughout the year in some individuals, which could be problematic when using fin rays for age estimation. The agreement of age estimates by two readers for shovelnose sturgeon was only 18%, and differences in ages between the two readers increased for older fish. The presence of split annuli, false annuli, spawning bands, imbedded rays, and deteriorating sections made individual growth rings difficult to separate. Our findings verified that opaque bands are formed annually during the summer in the pectoral fin rays of most shovelnose sturgeon, but some individuals form opaque bands during other times. Pectoral fin rays will probably continue to be the most practical method of age estimation in shovelnose sturgeon, but ages estimated by this method should be used with caution.

  12. Chaotic micromixer utilizing electro-osmosis and induced charge electro-osmosis in eccentric annulus

    Science.gov (United States)

    Feng, Huicheng; Wong, Teck Neng; Che, Zhizhao; Marcos

    2016-06-01

    Efficient mixing is of significant importance in numerous chemical and biomedical applications but difficult to realize rapidly in microgeometries due to the lack of turbulence. We propose to enhance mixing by introducing Lagrangian chaos through electro-osmosis (EO) or induced charge electro-osmosis (ICEO) in an eccentric annulus. The analysis reveals that the created Lagrangian chaos can achieve a homogeneous mixing much more rapidly than either the pure EO or the pure ICEO. Our systematic investigations on the key parameters, ranging from the eccentricity, the alternating time period, the number of flow patterns in one time period, to the specific flow patterns utilized for the Lagrangian chaos creation, present that the Lagrangian chaos is considerably robust. The system can obtain a good mixing effect with wide ranges of eccentricity, alternating time period, and specific flow patterns utilized for the Lagrangian chaos creation as long as the number of flow patterns in one time period is two. As the electric field increases, the time consumption for homogenous mixing is reduced more remarkably for the Lagrangian chaos of the ICEO than that of the EO.

  13. Preclinical positron emission tomography scanner based on a monolithic annulus of scintillator: initial design study.

    Science.gov (United States)

    Stolin, Alexander V; Martone, Peter F; Jaliparthi, Gangadhar; Raylman, Raymond R

    2017-01-01

    Positron emission tomography (PET) scanners designed for imaging of small animals have transformed translational research by reducing the necessity to invasively monitor physiology and disease progression. Virtually all of these scanners are based on the use of pixelated detector modules arranged in rings. This design, while generally successful, has some limitations. Specifically, use of discrete detector modules to construct PET scanners reduces detection sensitivity and can introduce artifacts in reconstructed images, requiring the use of correction methods. To address these challenges, and facilitate measurement of photon depth-of-interaction in the detector, we investigated a small animal PET scanner (called AnnPET) based on a monolithic annulus of scintillator. The scanner was created by placing 12 flat facets around the outer surface of the scintillator to accommodate placement of silicon photomultiplier arrays. Its performance characteristics were explored using Monte Carlo simulations and sections of the NEMA NU4-2008 protocol. Results from this study revealed that AnnPET's reconstructed spatial resolution is predicted to be [Formula: see text] full width at half maximum in the radial, tangential, and axial directions. Peak detection sensitivity is predicted to be 10.1%. Images of simulated phantoms (mini-hot rod and mouse whole body) yielded promising results, indicating the potential of this system for enhancing PET imaging of small animals.

  14. Fully automated software for mitral annulus evaluation in chronic mitral regurgitation by 3-dimensional transesophageal echocardiography.

    Science.gov (United States)

    Aquila, Iolanda; Fernández-Golfín, Covadonga; Rincon, Luis Miguel; González, Ariana; García Martín, Ana; Hinojar, Rocio; Jimenez Nacher, Jose Julio; Indolfi, Ciro; Zamorano, Jose Luis

    2016-12-01

    Three-dimensional (3D) transesophageal echocardiography (TEE) is the gold standard for mitral valve (MV) anatomic and functional evaluation. Currently, dedicated MV analysis software has limitations for its use in clinical practice. Thus, we tested here a complete and reproducible evaluation of a new fully automatic software to characterize MV anatomy in different forms of mitral regurgitation (MR) by 3D TEE.Sixty patients were included: 45 with more than moderate MR (28 organic MR [OMR] and 17 functional MR [FMR]) and 15 controls. All patients underwent TEE. 3D MV images obtained using 3D zoom were imported into the new software for automatic analysis. Different MV parameters were obtained and compared. Anatomic and dynamic differences between FMR and OMR were detected. A significant increase in systolic (859.75 vs 801.83 vs 607.78 mm; P = 0.002) and diastolic (1040.60 vs. 1217.83 and 859.74 mm; P software analysis automatically calculates several significant parameters that provide a correct and complete assessment of anatomy and dynamic mitral annulus geometry and displacement in the 3D space. This analysis allows a better characterization of MR pathophysiology and could be useful in designing new devices for MR repair or replacement.

  15. Two dimensional analysis of low pressure flows in the annulus region between two concentric cylinders.

    Science.gov (United States)

    Al-Kouz, Wael; Alshare, Aiman; Alkhalidi, Ammar; Kiwan, Suhil

    2016-01-01

    A numerical simulation of the steady two-dimensional laminar natural convection heat transfer for the gaseous low-pressure flows in the annulus region between two concentric horizontal cylinders is carried out. This type of flow occurs in "evacuated" solar collectors and in the receivers of the solar parabolic trough collectors. A finite volume code is used to solve the coupled set of governing equations. Boussinesq approximation is utilized to model the buoyancy effect. A correlation for the thermal conductivity ratio (k r = k eff/k) in terms of Knudsen number and the modified Rayleigh number is proposed for Prandtl number (Pr = 0.701). It is found that as Knudsen number increases then the thermal conductivity ratio decreases for a given Rayleigh number. Also, it is shown that the thermal conductivity ratio k r increases as Rayleigh number increases. It appears that there is no consistent trend for varying the dimensionless gap spacing between the inner and the outer cylinder ([Formula: see text]) on the thermal conductivity ratio (k r) for the considered spacing range.

  16. Subcooled flow boiling heat transfer of ethanol aqueous solutions in vertical annulus space

    Directory of Open Access Journals (Sweden)

    Sarafraz M.M.

    2012-01-01

    Full Text Available The subcooled flow boiling heat-transfer characteristics of water and ethanol solutions in a vertical annulus have been investigated up to heat flux 132kW/m2. The variations in the effects of heat flux and fluid velocity, and concentration of ethanol on the observed heat-transfer coefficients over a range of ethanol concentrations implied an enhanced contribution of nucleate boiling heat transfer in flow boiling, where both forced convection and nucleate boiling heat transfer occurred. Increasing the ethanol concentration led to a significant deterioration in the observed heat-transfer coefficient because of a mixture effect, that resulted in a local rise in the saturation temperature of ethanol/water solution at the vapor-liquid interface. The reduction in the heat-transfer coefficient with increasing ethanol concentration is also attributed to changes in the fluid properties (for example, viscosity and heat capacity of tested solutions with different ethanol content. The experimental data were compared with some well-established existing correlations. Results of comparisons indicate existing correlations are unable to obtain the acceptable values. Therefore a modified correlation based on Gnielinski correlation has been proposed that predicts the heat transfer coefficient for ethanol/water solution with uncertainty about 8% that is the least in comparison to other well-known existing correlations.

  17. Radiation effects on bifurcation and dual solutions in transient natural convection in a horizontal annulus

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Kang; Yi, Hong-Liang, E-mail: yihongliang@hit.edu.cn; Tan, He-Ping, E-mail: tanheping@hit.edu.cn [School of Energy Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2014-05-15

    Transitions and bifurcations of transient natural convection in a horizontal annulus with radiatively participating medium are numerically investigated using the coupled lattice Boltzmann and direct collocation meshless (LB-DCM) method. As a hybrid approach based on a common multi-scale Boltzmann-type model, the LB-DCM scheme is easy to implement and has an excellent flexibility in dealing with the irregular geometries. Separate particle distribution functions in the LBM are used to calculate the density field, the velocity field and the thermal field. In the radiatively participating medium, the contribution of thermal radiation to natural convection must be taken into account, and it is considered as a radiative term in the energy equation that is solved by the meshless method with moving least-squares (MLS) approximation. The occurrence of various instabilities and bifurcative phenomena is analyzed for different Rayleigh number Ra and Prandtl number Pr with and without radiation. Then, bifurcation diagrams and dual solutions are presented for relevant radiative parameters, such as convection-radiation parameter Rc and optical thickness τ. Numerical results show that the presence of volumetric radiation changes the static temperature gradient of the fluid, and generally results in an increase in the flow critical value. Besides, the existence and development of dual solutions of transient convection in the presence of radiation are greatly affected by radiative parameters. Finally, the advantage of LB-DCM combination is discussed, and the potential benefits of applying the LB-DCM method to multi-field coupling problems are demonstrated.

  18. Chaotic micromixer utilizing electro-osmosis and induced charge electro-osmosis in eccentric annulus

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Huicheng; Wong, Teck Neng, E-mail: mtnwong@ntu.edu.sg; Marcos [School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Che, Zhizhao [State Key Laboratory of Engines, Tianjin University, Tianjin 300072 (China)

    2016-06-15

    Efficient mixing is of significant importance in numerous chemical and biomedical applications but difficult to realize rapidly in microgeometries due to the lack of turbulence. We propose to enhance mixing by introducing Lagrangian chaos through electro-osmosis (EO) or induced charge electro-osmosis (ICEO) in an eccentric annulus. The analysis reveals that the created Lagrangian chaos can achieve a homogeneous mixing much more rapidly than either the pure EO or the pure ICEO. Our systematic investigations on the key parameters, ranging from the eccentricity, the alternating time period, the number of flow patterns in one time period, to the specific flow patterns utilized for the Lagrangian chaos creation, present that the Lagrangian chaos is considerably robust. The system can obtain a good mixing effect with wide ranges of eccentricity, alternating time period, and specific flow patterns utilized for the Lagrangian chaos creation as long as the number of flow patterns in one time period is two. As the electric field increases, the time consumption for homogenous mixing is reduced more remarkably for the Lagrangian chaos of the ICEO than that of the EO.

  19. Effect of Yield Power Law Fluid Rheological Properties on Cuttings Transport in Eccentric Horizontal Narrow Annulus

    Directory of Open Access Journals (Sweden)

    Titus Ntow Ofei

    2016-01-01

    Full Text Available Narrow annular drilling such as casing-while-drilling technique is gaining popularity due to its ability to mitigate nonproductive time during oil and gas drilling operations. However, very little is known about the flow dynamics in narrow annular drilling. In this study, the Eulerian-Eulerian two-fluid model was used to examine the influence of Yield Power Law fluid rheological properties on cuttings transport in eccentric horizontal narrow annulus. The flow was assumed as fully developed, laminar, and transient state. The present simulation model was validated against experimental data, where a mean percent error of −1.2% was recorded. Results revealed an increase in the radial distribution of cuttings transport velocity in the wide annular region as the consistency index, K, and the flow behavior index, n, increase. Nonetheless, increasing the yield stress, τo, had insignificant effect on the cuttings transport velocity. Three-dimensional profiles showed how cuttings preferred to travel in less resistant flow area, whereas cuttings concentration builds up in the narrow annular region. Furthermore, annular frictional pressure losses also increased as K, n, and τo increased. This study serves as a guide to properly optimize drilling fluid rheological properties for efficient cuttings transport and equivalent circulating density (ECD management in narrow annular drilling.

  20. [Long-term results of conventional aortic valve replacement for small aortic annulus].

    Science.gov (United States)

    Miura, Y; Miyairi, T; Kitamura, T; Kigawa, I; Fukuda, S

    2006-04-01

    We studied cardiac function, clinical outcome and quality of life (QOL) long after aortic valve replacement for pure aortic stenosis. Forty-four patients in small group [St. Jude Medical (SJM) 17 HP, 19 A], and 69 patients in non-small group (19 HP, 21 A, 23 A) operated on from 1984 to 2004 were enrolled in this study. We assessed the clinical data, aortic pressure gradient, left ventricular mass index (LVMI), and ejection fraction (EF) by preoperative and postoperative echocardiography. Moreover to evaluate QOL after the operation, we performed SF-36 used for the evaluation of health and QOL worldwide. Mean follow-up is 7.1 +/- 4.8 years in small group, and 6.8 +/- 4.6 years in non-small group. There were 2 hospital deaths in small group, and 1 in non-small group. The actual survival rate at 10-year were 89.2% in small group, and 85.6% in non-small group. There was no significant difference in hospital mortality, LVMI, long-term survival rate, and the scores of SF-36 between the 2 groups. The use of small sized prosthetic valves in patients with small aortic annulus might be justified when there is no patient-prosthesis mismatch.

  1. Enlargement of the aortic annulus during aortic valve replacement: a review.

    Science.gov (United States)

    Bortolotti, Uberto; Celiento, Michele; Milano, Aldo D

    2014-01-01

    The main goal of aortic valve replacement (AVR) is to obtain relief from the fixed left ventricular (LV) obstruction by replacing the aortic valve with a prosthesis, either mechanical or biological, of adequate size. Most currently available prostheses provide satisfactory hemodynamic performance, but small-sized prostheses may be associated with high transvalvular gradients and suboptimal effective orifice area that result in prosthesis-patient mismatch (PPM), and thus are far from ideal for use in young, active patients. The avoidance of PPM is advisable as it has been repeatedly associated with increased mortality, decreased exercise tolerance and an impaired regression of LV hypertrophy after AVR for severe aortic stenosis. Enlargement of the aortic annulus (EAA) has proved to be a valuable method to prevent PPM in the presence of a diminutive aortic root. This review outlines the various techniques described for EAA, presenting technical details, long-term results and major procedure-related complications, and discussing the current role of EAA in patients requiring AVR.

  2. Experiments on transitions of baroclinic waves in a differentially heated rotating annulus

    Directory of Open Access Journals (Sweden)

    Th. von Larcher

    2005-01-01

    Full Text Available Experiments of baroclinic waves in a rotating, baroclinic annulus of fluid are presented for two gap widths. The apparatus is a differentially heated cylindrical gap, rotated around its vertical axis of symmetry, cooled from within, with a free surface, and filled with de-ionised water as working fluid. The surface flow was observed with visualisation technique while thermographic measurements gave a detailed understanding of the temperature distribution and its time-dependent behaviour. We focus in particular on transitions between different flow regimes. Using a wide gap, the first transition from axisymmetric flow to the regular wave regime was characterised by complex flows. The transition to irregular flows was smooth, where a coexistence of the large-scale jet-stream and small-scale vortices was observed. Furthermore, temperature measurements showed a repetitive separation of cold vortices from the inner wall. Experiments using a narrow gap showed no complex flows but strong hysteresis in the steady wave regime, with up to five different azimuthal wave modes as potential steady and stable solutions.

  3. Benchmarking in a rotating annulus: a comparative experimental and numerical study of baroclinic wave dynamics

    Directory of Open Access Journals (Sweden)

    Miklos Vincze

    2015-01-01

    Full Text Available The differentially heated rotating annulus is a widely studied tabletop-size laboratory model of the general mid-latitude atmospheric circulation. The two most relevant factors of cyclogenesis, namely rotation and meridional temperature gradient are quite well captured in this simple arrangement. The radial temperature difference in the cylindrical tank and its rotation rate can be set so that the isothermal surfaces in the bulk tilt, leading to the formation of baroclinic waves. The signatures of these waves at the free water surface have been analyzed via infrared thermography in a wide range of rotation rates (keeping the radial temperature difference constant and under different initial conditions. In parallel to the laboratory experiments, five groups of the MetStröm collaboration have conducted numerical simulations in the same parameter regime using different approaches and solvers, and applying different initial conditions and perturbations. The experimentally and numerically obtained baroclinic wave patterns have been evaluated and compared in terms of their dominant wave modes, spatio-temporal variance properties and drift rates. Thus certain “benchmarks” have been created that can later be used as test cases for atmospheric numerical model validation.

  4. Educing the emission mechanism of internal gravity waves in the differentially heat rotating annulus

    Science.gov (United States)

    Rolland, Joran; Hien, Steffen; Achatz, Ulrich; Borchert, Sebastian; Fruman, Mark

    2016-04-01

    Understanding the lifecycle of gravity waves is fundamental to a good comprehension of the dynamics of the atmosphere. In this lifecycle, the emission mechanisms may be the most elusive. Indeed, while the emission of gravity waves by orography or convection is well understood, the so-called spontaneous emission is still a quite open topic of investigation [1]. This type of emission usually occur very near jet-front systems in the troposphere. In this abstract, we announce our numerical study of the question. Model systems of the atmosphere which can be easily simulated or built in a laboratory have always been an important part of the study of atmospheric dynamics, alongside global simulations, in situ measurements and theory. In the case of the study of the spontaneous emission of gravity waves near jet-front systems, the differentially heated rotating annulus set up has been proposed and extensively used. It comprises of an annular tank containing water: the inner cylinder is kept at a cold temperature while the outer cylinder is kept at a warm temperature. The whole system is rotating. Provided the values of the control parameters (temperature, rotation rate, gap between the cylinders, height of water) are well chosen, the resulting flow mimics the troposphere at midlatitudes: it has a jet stream, and a baroclinic lifecycle develops on top of it. A very reasonable ratio of Brunt-Väisälä frequency over rotation rate of the system can be obtained, so as to be as close to the atmosphere as possible. Recent experiments as well as earlier numerical simulations in our research group have shown that gravity waves are indeed emitted in this set up, in particular near the jet front system of the baroclinic wave [2]. After a first experimental stage of characterising the emitted wavepacket, we focused our work on testing hypotheses on the gravity wave emission mechanism: we have tested and validated the hypothesis of spontaneous imbalance generated by the flow in

  5. Empirical singular vectors of baroclinic flows deduced from experimental data of a differentially heated rotating annulus

    Directory of Open Access Journals (Sweden)

    Michael Hoff

    2015-01-01

    Full Text Available Instability is related to exponentially growing eigenmodes. Interestingly, when finite time intervals are considered, growth rates of certain initial perturbations can exceed the growth rates of the most unstable modes. Moreover, even when all modes are damped, such particular initial perturbations can still grow during finite time intervals. The perturbations with the largest growth rates are called singular vectors (SVs or optimal perturbations. They not only play an important role in atmospheric ensemble predictions, but also for the theory of instability and turbulence. Starting point for a classical SV-analysis is a linear dynamical system with a known system matrix. In contrast to this traditional approach, measured data are used here to estimate the linear propagator. For this estimation, a method is applied that uses the covariances of the measured time series to find the principal oscillation patterns (POPs that are the empirically estimated linear eigenmodes of the system. By using the singular value decomposition (SVD, we can estimate the modes of maximal growth of the propagator which are thus the empirically estimated SVs. These modes can be understood as a superposition of POPs that form a complete but in general non-orthogonal basis. The data used, originate from a differentially heated rotating annulus laboratory experiment. This experiment is an analogue of the earth's atmosphere and is used to study the development of baroclinic waves in a well controlled and reproducible way without the need of numerical approximations. Baroclinic waves form the background for many studies on SV growth and it is thus straight forward to apply the technique of empirical SV estimation to these laboratory data. To test the method of SV estimation, we use a quasi-geostrophic barotropic model and compare the known SVs from that model with SVs estimated from a surrogate data set that was generated with the help of the exact model propagator and some

  6. The safe removal of frozen air from the annulus of an LH2 storage tank

    Science.gov (United States)

    Krenn, A.; Starr, S.; Youngquist, R.; Nurge, M.; Sass, J.; Fesmire, J.; Cariker, C.; Bhattacharya, A.

    2015-12-01

    Large Liquid Hydrogen (LH2) storage tanks are vital infrastructure for NASA. Eventually, air may leak into the evacuated and perlite filled annular region of these tanks. Although the vacuum level is monitored in this region, the extremely cold temperature causes all but the helium and neon constituents of air to freeze. A small, often unnoticeable pressure rise is the result. As the leak persists, the quantity of frozen air increases, as does the thermal conductivity of the insulation system. Consequently, a notable increase in commodity boil-off is often the first indicator of an air leak. Severe damage can result from normal draining of the tank. The warming air will sublimate which will cause a pressure rise in the annulus. When the pressure increases above the triple point, the frozen air will begin to melt and migrate downward. Collection of liquid air on the carbon steel outer shell may chill it below its ductility range, resulting in fracture. In order to avoid a structural failure, as described above, a method for the safe removal of frozen air is needed. A thermal model of the storage tank has been created using SINDA/FLUINT modelling software. Experimental work is progressing in an attempt to characterize the thermal conductivity of a perlite/frozen nitrogen mixture. A statistical mechanics model is being developed in parallel for comparison to experimental work. The thermal model will be updated using the experimental/statistical mechanical data, and used to simulate potential removal scenarios. This paper will address methodologies and analysis techniques for evaluation of two proposed air removal methods.

  7. Atmospheric-like rotating annulus experiment: gravity wave emission from baroclinic jets

    Science.gov (United States)

    Rodda, Costanza; Borcia, Ion; Harlander, Uwe

    2017-04-01

    Large-scale balanced flows can spontaneously radiate meso-scale inertia-gravity waves (IGWs) and are thus in fact unbalanced. While flow-dependent parameterizations for the radiation of IGWs from orographic and convective sources do exist, the situation is less developed for spontaneously emitted IGWs. Observations identify increased IGW activity in the vicinity of jet exit regions. A direct interpretation of those based on geostrophic adjustment might be tempting. However, directly applying this concept to the parameterization of spontaneous imbalance is difficult since the dynamics itself is continuously re-establishing an unbalanced flow which then sheds imbalances by GW radiation. Examining spontaneous IGW emission in the atmosphere and validating parameterization schemes confronts the scientist with particular challenges. Due to its extreme complexity, GW emission will always be embedded in the interaction of a multitude of interdependent processes, many of which are hardly detectable from analysis or campaign data. The benefits of repeated and more detailed measurements, while representing the only source of information about the real atmosphere, are limited by the non-repeatability of an atmospheric situation. The same event never occurs twice. This argues for complementary laboratory experiments, which can provide a more focused dialogue between experiment and theory. Indeed, life cycles are also examined in rotating- annulus laboratory experiments. Thus, these experiments might form a useful empirical benchmark for theoretical and modelling work that is also independent of any sort of subgrid model. In addition, the more direct correspondence between experimental and model data and the data reproducibility makes lab experiments a powerful testbed for parameterizations. Joint laboratory experiment and numerical simulation have been conducted. The comparison between the data obtained from the experiment and the numerical simulations shows a very good

  8. The Safe Removal of Frozen Air from the Annulus of an LH2 Storage Tank

    Science.gov (United States)

    Krenn, A.; Starr, S.; Youngquist, R.; Nurge, M.; Sass, J.; Fesmire, J.; Cariker, C.; Bhattacharya, A.

    2015-01-01

    Large Liquid Hydrogen (LH2) storage tanks are vital infrastructure for NASA. Eventually, air may leak into the evacuated and perlite filled annular region of these tanks. Although the vacuum level is monitored in this region, the extremely cold temperature causes all but the helium and neon constituents of air to freeze. A small, often unnoticeable pressure rise is the result. As the leak persists, the quantity of frozen air increases, as does the thermal conductivity of the insulation system. Consequently, a notable increase in commodity boil-off is often the first indicator of an air leak. Severe damage can result from normal draining of the tank. The warming air will sublimate which will cause a pressure rise in the annulus. When the pressure increases above the triple point, the frozen air will begin to melt and migrate downward. Collection of liquid air on the carbon steel outer shell may chill it below its ductility range, resulting in fracture. In order to avoid a structural failure, as described above, a method for the safe removal of frozen air is needed. A thermal model of the storage tank has been created using SINDA/FLUINT modeling software. Experimental work is progressing in an attempt to characterize the thermal conductivity of a perlite/frozen nitrogen mixture. A statistical mechanics model is being developed in parallel for comparison to experimental work. The thermal model will be updated using the experimental/statistical mechanical data, and used to simulate potential removal scenarios. This paper will address methodologies and analysis techniques for evaluation of two proposed air removal methods.

  9. Fully automated software for mitral annulus evaluation in chronic mitral regurgitation by 3-dimensional transesophageal echocardiography

    Science.gov (United States)

    Aquila, Iolanda; Fernández-Golfín, Covadonga; Rincon, Luis Miguel; González, Ariana; García Martín, Ana; Hinojar, Rocio; Jimenez Nacher, Jose Julio; Indolfi, Ciro; Zamorano, Jose Luis

    2016-01-01

    Abstract Three-dimensional (3D) transesophageal echocardiography (TEE) is the gold standard for mitral valve (MV) anatomic and functional evaluation. Currently, dedicated MV analysis software has limitations for its use in clinical practice. Thus, we tested here a complete and reproducible evaluation of a new fully automatic software to characterize MV anatomy in different forms of mitral regurgitation (MR) by 3D TEE. Sixty patients were included: 45 with more than moderate MR (28 organic MR [OMR] and 17 functional MR [FMR]) and 15 controls. All patients underwent TEE. 3D MV images obtained using 3D zoom were imported into the new software for automatic analysis. Different MV parameters were obtained and compared. Anatomic and dynamic differences between FMR and OMR were detected. A significant increase in systolic (859.75 vs 801.83 vs 607.78 mm2; P = 0.002) and diastolic (1040.60 vs. 1217.83 and 859.74 mm2; P < 0.001) annular sizes was observed in both OMR and FMR compared to that in controls. FMR had a reduced mitral annular contraction compared to degenerative cases of OMR and to controls (17.14% vs 32.78% and 29.89%; P = 0.007). Good reproducibility was demonstrated along with a short analysis time (mean 4.30 minutes). Annular characteristics and dynamics are abnormal in both FMR and OMR. Full 3D software analysis automatically calculates several significant parameters that provide a correct and complete assessment of anatomy and dynamic mitral annulus geometry and displacement in the 3D space. This analysis allows a better characterization of MR pathophysiology and could be useful in designing new devices for MR repair or replacement. PMID:27930514

  10. 主动脉瓣环扩大术在主动脉瓣置换术中的应用%Aortic annulus enlargement in aortic valve replacement for small aortic annulus

    Institute of Scientific and Technical Information of China (English)

    朱水波; 殷桂林; 胡健才; 张殿堂; 张晓明; 王荣平; 谭焱; 高旭辉; 刘勇

    2012-01-01

    Objective To summarize the experiences of aortic annulus enlargement in aortic valve replacement for small aortic annulus. Methods From Jan. 2000 to Sept,2010,18 cases of aortic valve disease with small aortic annulus received improved Manouguian procedure to enlarge the small aortic annulus before implanting appropriate mechanical aortic valve. Complicated heart lesion were treated surgically simultaneously. Results Complications in early stage including ventricular arrhythmia, severe low cardiac output syndrome and cardiac tamponade were cured. All cases were discharged without operative mortality. All cases were improved in cardiac function and ventricular wall mass. No death or other severe events occurred in follow - up. Conclusion Aortic annulus enlargement with improved Manougnian method is effective and safe in patients with small aortic annulus in order to implant appropriate mechanical aortic valve.%目的 总结主动脉瓣置换术中处理小主动脉瓣环的体会.方法 我院在2000年至2010年期间收治主动脉瓣环细小的主动脉瓣病变18例,均采取改良Manouguian方法扩大主动脉瓣环,再置入较合适的机械主动脉瓣.同期行二尖瓣置换6例,室间隔修补1例,三尖瓣成形5例.结果 17例有效开口面积指数(EOAI)均达到0.85cm2/m2以上,1例0.80cm2/m2.术后严重低心排综合征1例,室性心律失常3例,心脏压塞1例.18例痊愈出院,随访1~10年,术后6个月复查发现EOAI为0.80cm2/m2的患者主动脉跨瓣压差较高,室间隔及左室壁厚度恢复较慢,左室射血分数较低;而比值在0.85~1.0之间与大于1.0的患者相比,主动脉跨瓣压差、室间隔及左室壁厚度平均值稍高,但差异无统计学意义.2例术后6年因身高、体重增加EOAI分别下降到0.79、0.81cm2/m2,出现活动后心慌,心电图提示左室高电压,经扩管等药物治疗和一般处理,症状明显改善.结论 改良Manouguian方法扩大主动脉瓣环安全、有效,可置入

  11. Spinal traction promotes molecular transportation in a simulated degenerative intervertebral disc model.

    Science.gov (United States)

    Kuo, Ya-Wen; Hsu, Yu-Chun; Chuang, I-Ting; Chao, Pen-Hsiu Grace; Wang, Jaw-Lin

    2014-04-20

    Biomechanical experiment using an in situ porcine model. To find the effect of traction treatment on annulus microstructure, molecular convection, and cell viability of degraded discs. Spinal traction is a conservative treatment for disc disorders. The recognized biomechanical benefits include disc height recovery, foramen enlargement, and intradiscal pressure reduction. However, the influence of traction treatment on annulus microstructure, molecular transportation, and cell viability of degraded discs has not been fully investigated. A total of 48 thoracic discs were dissected from 8 porcine spines (140 kg, 6-month old) within 4 hours after killing them and then divided into 3 groups: intact, degraded without traction, and degraded with traction. Each disc was incubated in a whole-organ culture system and subjected to diurnal loadings for 7 days. Except for the intact group, discs were degraded with 0.5 mL of trypsin on day 1 and a 5-hour fatigue loading on day 2. From day 4 to day 6, half of the degraded discs received a 30-minute traction treatment per day (traction force: 20 kg; loading: unloading = 30 s: 10 s). By the end of the incubation, the discs were inspected for disc height loss, annulus microstructure, molecular (fluorescein sodium) intensity, and cell viability. Collagen fibers were crimped and delaminated, whereas the pores were occluded in the annulus fibrosus of the degraded discs. Molecular transportation and cell viability of the discs decreased after matrix degradation. With traction treatment, straightened collagen fibers increased within the degraded annulus fibrosus, and the annulus pores were less occluded. Both molecular transportation and cell viability increased, but not to the intact level. Traction treatment is effective in enhancing nutrition supply and promoting disc cell proliferation of the degraded discs. N/A.

  12. Aortic annulus eccentricity before and after transcatheter aortic valve implantation: Comparison of balloon-expandable and self-expanding prostheses

    Energy Technology Data Exchange (ETDEWEB)

    Schuhbaeck, Annika, E-mail: annika.schuhbaeck@uk-erlangen.de [Department of Cardiology, University of Erlangen, Erlangen (Germany); Weingartner, Christina [Department of Cardiology, University of Gießen, Giessen (Germany); Arnold, Martin; Schmid, Jasmin; Pflederer, Tobias; Marwan, Mohamed [Department of Cardiology, University of Erlangen, Erlangen (Germany); Rixe, Johannes; Nef, Holger [Department of Cardiology, University of Gießen, Giessen (Germany); Schneider, Christian [Department of Radiology, University of Gießen, Giessen (Germany); Lell, Michael; Uder, Michael [Department of Radiology, University of Erlangen, Erlangen (Germany); Ensminger, Stephan [Department of Thoracic and Cardiovascular Surgery, Heart and Diabetes Center NRW, Ruhr-University Bochum, Bad Oeynhausen (Germany); Feyrer, Richard; Weyand, Michael [Department of Cardiothoracic Surgery, University of Erlangen, Erlangen (Germany); Achenbach, Stephan [Department of Cardiology, University of Erlangen, Erlangen (Germany)

    2015-07-15

    Highlights: • Post-implant geometry of catheter-based aortic valve prostheses is influenced by aortic valve calcification. • Balloon-expandable prostheses are more circular as compared to self-expanding prostheses. • The impact of post-implant geometry on valve function needs to be investigated. - Abstract: Introduction: The geometry of the aortic annulus and implanted transcatheter aortic valve prosthesis might influence valve function. We investigated the influence of valve type and aortic valve calcification on post-implant geometry of catheter-based aortic valve prostheses. Methods: Eighty consecutive patients with severe aortic valve stenosis (mean age 82 ± 6 years) underwent computed tomography before and after TAVI. Aortic annulus diameters were determined. Influence of prosthesis type and degree of aortic valve calcification on post-implant eccentricity were analysed. Results: Aortic annulus eccentricity was reduced in patients after TAVI (0.21 ± 0.06 vs. 0.08 ± 0.06, p < 0.0001). Post-TAVI eccentricity was significantly lower in 65 patients following implantation of a balloon-expandable prosthesis as compared to 15 patients who received a self-expanding prosthesis (0.06 ± 0.05 vs. 0.15 ± 0.07, p < 0.0001), even though the extent of aortic valve calcification was not different. After TAVI, patients with a higher calcium amount retained a significantly higher eccentricity compared to patients with lower amounts of calcium. Conclusions: Patients undergoing TAVI with a balloon-expandable prosthesis show a more circular shape of the implanted prosthesis as compared to patients with a self-expanding prosthesis. Eccentricity of the deployed prosthesis is affected by the extent of aortic valve calcification.

  13. [New technique of concomitant replacement of the aortic valve and the ascending aorta with enlargement of the aortic annulus for congenital bicuspid aortic valve].

    Science.gov (United States)

    Takahara, Shingo; Fukasawa, Manabu; Kawahara, Yu; Suzuki, Kotaro; Kobayashi, Yuriko

    2012-12-01

    Congenital bicuspid aortic valve (BAV) is one of the most common congenital heart diseases, with a high incidence of associated valvular lesions and aortic abnormalities including aortic stenosis( AS), aortic regurgitation, aortic dilatation, and aortic dissection. Patients with BAV and AS often have a small aortic annulus. We encountered a case of BAV in which a 51-year-old woman with severe AS having a small aortic annulus and a dilated ascending aorta required surgical intervention. We performed the surgery using new technique that involved concomitant replacement of the aortic valve and the ascending aorta with enlargement of the aortic annulus using a single uniquely-shaped graft to avoid prosthesis patient mismatch. We trimmed the proximal end of the straight graft in shape of 2 teardrops hanging on it to fit the cut annulus. It requires only a single suture line to replace the ascending aorta and enlarge the aortic annulus, which entails a decreased risk of bleeding during surgery. We believe that it could be applicable to many cases requiring concomitant surgery.

  14. NUMERICAL SIMULATION OF UNSTEADY FLOW FOR VISCO-ELASTIC FLUID IN AN ECCENTRIC ANNULUS WITH INNER ROD RECIPROCATION

    Institute of Scientific and Technical Information of China (English)

    HE Feng-yun; YANG Shu-ren

    2008-01-01

    The equation governing the unsteady flow of viscoelastic fluids in an eccentric annulus was derived by using the common conversion Maxwell fluid constitutive equation and then discretized by the control volume method. The velocity distribution of flow field was computed by using the ADI method. The influences of the pressure gradient, eccentricity, stroke length, and stroke frequency on the velocity and flow capacity in the flow field was analyzed. The foundation for further research of the eccentric wear problem of the pumping rod in polymer-flood well was laid.

  15. Influence factors on stress corrosion cracking of P110 tubing steel under CO2 injection well annulus environment

    Institute of Scientific and Technical Information of China (English)

    刘然克; 贾静焕; 杜翠薇; 李晓刚

    2016-01-01

    Stress corrosion cracking (SCC) behavior of P110 tubing steel in simulated CO2 injection well annulus environments was investigated through three-point bent tests, potentiodynamic polarization and EIS measurements. The results demonstrate that SCC of P110 tubing steel could occur in acidulous simulated environment, and the sensitivity of SCC increases with the decrease of pH, as well as increase of sulfide concentration and total environmental pressure. Both anodic dissolution and hydrogen embrittlement make contributions to the SCC. Adequate concentration of corrosion inhibitor can inhibit the occurrence of SCC on account of the inhibition of localized anodic dissolution and cathodic hydrogen evolution.

  16. Effects of Slotted Structures on Nonlinear Characteristics of Natural Convection in a Cylinder with an Internal Concentric Slotted Annulus

    CERN Document Server

    Shen, Chunyun; Zhang, Yuwen; Li, Zheng

    2016-01-01

    Natural convection in a cylinder with an internally slotted annulus was solved by SIMPLE algorithm, and the effects of different slotted structures on nonlinear characteristics of natural convection were investigated. The results show that the equivalent thermal conductivity Keq increases with Rayleigh number, and reaches the maximum in the vertical orientation. Nonlinear results were obtained by simulating the fluid flow at different conditions. With increasing Rayleigh number, heat transfer is intensified and the state of heat transfer changes from the steady to unsteady. We investigated different slotted structures effects on natural convection, and analyze the corresponding nonlinear characteristics.

  17. Simultaneous effects of single wall carbon nanotube and effective variable viscosity for peristaltic flow through annulus having permeable walls

    Science.gov (United States)

    Shahzadi, Iqra; Nadeem, S.; Rabiei, Faranak

    The current article deals with the combine effects of single wall carbon nanotubes and effective viscosity for the peristaltic flow of nanofluid through annulus. The nature of the walls is assumed to be permeable. The present theoretical model can be considered as mathematical representation to the motion of conductive physiological fluids in the existence of the endoscope tube which has many biomedical applications such as drug delivery system. The outer tube has a wave of sinusoidal nature that is travelling along its walls while the inner tube is rigid and uniform. Lubrication approach is used for the considered analysis. An empirical relation for the effective variable viscosity of nanofluid is proposed here interestingly. The viscosity of nanofluid is the function of radial distance and the concentration of nanoparticles. Exact solution for the resulting system of equations is displayed for various quantities of interest. The outcomes show that the maximum velocity of SWCNT-blood nanofluid enhances for larger values of viscosity parameter. The pressure gradient in the more extensive part of the annulus is likewise found to increase as a function of variable viscosity parameter. The size of the trapped bolus is also influenced by variable viscosity parameter. The present examination also revealed that the carbon nanotubes have many applications related to biomedicine.

  18. New Annulus Testing Pipe String Development%新型环空测试工艺管柱研制

    Institute of Scientific and Technical Information of China (English)

    于洋洋; 高翔; 刘宇飞

    2016-01-01

    Annulus logging technology has the following advantage,less working procedure,high data accuracy,so it was favored by the oil field.With the development of oil field,but with the in-crease of the deepening of oilfield development and deep deviated well,the inadaptability of the annulus test technology is gradually emerging,cable winding has appeared,a crescent shaped space is insufficient,decentralized wellhead rebound and other issues.To solve these problems, small tubing ring empty testing pipe string was designed,and three kinds of supporting tools are researched,especially the downhole tubing rotator,effective solve the pipe string rotation prob-lems in deviated well.%针对环空测试工艺技术出现电缆缠绕、“月牙形”空间不足、偏心井口反弹等问题,设计了小油管环空测试工艺管柱,并研发了3种配套工具,特别是井下油管旋转器,有效解决了斜井管柱转不动的问题。

  19. Defective Tbx2-dependent patterning of the atrioventricular canal myocardium causes accessory pathway formation in mice

    NARCIS (Netherlands)

    Aanhaanen, W.T.J.; Boukens, B.J.D.; Sizarov, A.; Wakker, V.; de Gier- de Vries, C.; van Ginneken, A.C.; Moorman, A.F.M.; Coronel, R.; Christoffels, V.M.

    2011-01-01

    Ventricular preexcitation, a feature of Wolff-Parkinson-White syndrome, is caused by accessory myocardial pathways that bypass the annulus fibrosus. This condition increases the risk of atrioventricular tachycardia and, in the presence of atrial fibrillation, sudden death. The developmental

  20. Herniated Lumbar Disc

    Science.gov (United States)

    ... made of a tough outer layer called the "annulus fibrosus" and a gel-like center called the " ... clearly, sometimes it is necessary to remove a small portion of the lamina, the bone behind the ...

  1. Lumbar (Open) Microscopic Discectomy

    Science.gov (United States)

    ... When the outer wall of a disc, the annulus fibrosus, becomes weakened, it may tear allowing the ... and alleviate the pain. The surgery involves a small incision in the skin over the spine, removal ...

  2. PRESSURE DISTRIBUTION ON THE WALL OF THE INNER CYLINDER RECIPROCATING AXIALLY TO THE UNSTEADY FLOW OF VISCOELASTIC FLUID IN ECCENTRIC ANNULUS

    Institute of Scientific and Technical Information of China (English)

    WANG Yan; CUI Hai-qing; YANG Yuan-jian; GUO Jun-hui; LI Nan

    2006-01-01

    In this article, the governing equations for the unsteady flow of viscoelastic fluid in the eccentric annulus with the inner cylinder reciprocating axially and the expression of the pressure distribution on the wall of the inner cylinder of the annulus are established and derived, respectively, under the bipolar coordinate system.The equations and the expression are solved and calculated numerically using the finite difference method, respectively.The curves of the pressure distribution on the wall of the inner cylinder of the aqueous solution of Hydrolyzed Polyacrylamide (HPAM) are plotted and the influences of annular eccentricity, stroke, and stroke frequency on the pressure distribution are analyzed.

  3. Biomechanical testing of a polymer-based biomaterial for the restoration of spinal stability after nucleotomy

    Directory of Open Access Journals (Sweden)

    Kaps Christian

    2009-07-01

    Full Text Available Abstract Background Surgery for disc herniations can be complicated by two major problems: painful degeneration of the spinal segment and re-herniation. Therefore, we examined an absorbable poly-glycolic acid (PGA biomaterial, which was lyophilized with hyaluronic acid (HA, for its utility to (a re-establish spinal stability and to (b seal annulus fibrosus defects. The biomechanical properties range of motion (ROM, neutral zone (NZ and a potential annulus sealing capacity were investigated. Methods Seven bovine, lumbar spinal units were tested in vitro for ROM and NZ in three consecutive stages: (a intact, (b following nucleotomy and (c after insertion of a PGA/HA nucleus-implant. For biomechanical testing, spinal units were mounted on a loading-simulator for spines. In three cycles, axial loading was applied in an excentric mode with 0.5 Nm steps until an applied moment of ± 7.5 Nm was achieved in flexion/extension. ROM and NZ were assessed. These tests were performed without and with annulus sealing by sewing a PGA/HA annulus-implant into the annulus defect. Results Spinal stability was significantly impaired after nucleotomy (p Conclusion PGA/HA biomaterial seems to be well suited for cell-free and cell-based regenerative treatment strategies in spinal surgery. Its abilities to restore spinal stability and potentially close annulus defects open up new vistas for regenerative approaches to treat intervertebral disc degeneration and for preventing implant herniation.

  4. Automated 3D Analysis of Pre-Procedural MDCT to Predict Annulus Plane Angulation and C-Arm Positioning Benefit on Procedural Outcome in Patients Referred for TAVR

    NARCIS (Netherlands)

    Samim, Mariam; Stella, Pieter R.; Agostoni, Pierfrancesco; Kluin, Jolanda; Ramjankhan, Faiez; Budde, Ricardo P. J.; Sieswerda, Gertjan; Algeri, Emanuela; van Belle, Camille; Elkalioubie, Ahmed; Juthier, Francis; Belkacemi, Anouar; Bertrand, Michel E.; Doevendans, Pieter A.; Van Belle, Eric

    2013-01-01

    OBJECTIVES The aim of this study was to determine whether pre-procedural analysis of multidetector row computed tomography (MDCT) scans could accurately predict the "line of perpendicularity" (LP) of the aortic annulus and corresponding C-arm angulations required for prosthesis delivery and impact t

  5. An experimental study of regime transitions in a differentially heated baroclinic annulus with flat and sloping bottom topographies

    CERN Document Server

    Vincze, Miklos; von Larcher, Thomas; Egbers, Christoph

    2013-01-01

    A series of laboratory experiments has been carried out in a thermally driven rotating annulus to study the onset of baroclinic instability, using horizontal and uniformly sloping bottom topographies. Different wave flow regimes have been identified and their phase boundaries -- expressed in terms of appropriate non-dimensional parameters -- have been compared to the recent numerical results of \\citet{thomas_slope}. In the flat bottom case, the numerically predicted alignment of the boundary between the axisymmetric and the regular wave flow regime was found to be consistent with the experimental results. However, once the sloping bottom end wall was introduced, the detected behaviour was qualitatively different from that of the simulations. This disagreement is thought to be the consequence of nonlinear wave-wave interactions that could not be resolved in the framework of the numerical study. This argument is supported by the observed development of interference vacillation in the runs with sloping bottom, a...

  6. Study on solid liquid interface heat transfer of PCM under simultaneous charging and discharging (SCD) in horizontal cylinder annulus

    Science.gov (United States)

    Omojaro, Adebola Peter; Breitkopf, Cornelia

    2017-07-01

    Heat transfer performance during the simultaneous charging and discharging (SCD) operation process for phase change materials (PCM) contained inside the annulus of concentric horizontal cylinder was investigated. In the experimental set-up, the PCM inside the annulus serves as the heat sink along with an externally imposed forced cooling air. The obtained time wise temperature profile was used to determine the effects of different heat fluxes and the imposed forced convection cooling on the melt fraction values and the transition shift time from the observed conduction to natural convection heat transfer patterns. Furthermore, non-dimensional analysis was presented for the heat transfer at the interface to enable generalizing the result. Comparison of the results show that the SCD operation mode establish the condition that enables much PCM phase transition time and thus longer time of large latent heat transfer effect than the Partial and non simultaneous operations. Analysis results show that the variation of the heat flux for the SCD mode did not change the dominance of the natural convection over conduction heat transfers in the PCM. However, it significantly influences the commencement/transition shift time and melting rate while higher heat fluxes yields melt fraction that was 38-63% more for investigated process time. Variation with different cooling air flow rate shows more influences on the melt fraction than on the mode of heat transfer occurring in the PCM during melting. Available non-SCD modes correlation was shown to be insufficient to accurately predict interface heat transfer for the SCD modes.

  7. Primary limited lumbar discectomy with an annulus closure device: one-year clinical and radiographic results from a prospective, multi-center study.

    Science.gov (United States)

    Lequin, Michiel B; Barth, Martin; Thomė, Claudius; Bouma, Gerrit J

    2012-12-01

    Discectomy as a treatment for herniated lumbar discs results in outcomes after surgery that are not uniformly positive. Surgeons face the dilemma between limited nucleus removal which is associated with a higher risk of recurrence, or more aggressive nucleus removal which may lead to disc height loss and persistent back-pain. annulus closure devices may allow for the benefits of limited nucleus removal without the increased risk of recurrence. This is an interim report of an ongoing 24-month post-marketing study of the Barricaid® annulus closure device, consisting of a flexible polymer mesh that blocks the defect, held in place by a titanium bone anchor. We prospectively enrolled 45 patients at four hospitals, and implanted the Barricaid® after a limited discectomy. annulus defect size and volume of removed nucleus were recorded. Reherniations were reported, pain and function were monitored and imaging was performed at regular intervals during 24 months of follow-up. At 12 months postsurgery, pain and function were significantly improved, comparing favorably to reported results from limited discectomy. Disc height has been well maintained. One reherniation has occurred (2.4%), which was associated with a misplaced device. No device fracture, subsidence or migration has been observed. The use of an annulus closure device may provide a reduction in reherniation rate for lumbar discectomy patients with large annulus defects who are at the greatest risk of recurrence. Using such a device should provide the surgeon increased confidence in minimizing nucleus removal, which, in turn, may preserve disc height and biomechanics, reducing degeneration and associated poor clinical outcomes in the long-term. A randomized multicenter study evaluating limited discectomy with and without the Barricaid® is currently underway, and will provide a higher level of evidence.

  8. Role of Inclined Magnetic Field and Copper Nanoparticles on Peristaltic Flow of Nanofluid through Inclined Annulus: Application of the Clot Model

    Science.gov (United States)

    Shahzadi, Iqra; Nadeem, S.

    2017-06-01

    A genuine neurotic condition is experienced when some blood constituents accumulate on the wall of the artery get withdrew from the wall, again join the circulatory system and coagulation occur. Role of copper nanoparticles and inclined magnetic field on the peristaltic flow of a nanofluid in an annular region of inclined annulus is investigated. We represent the clot model by considering the small artery as an annulus whose outer tube has a wave of sinusoidal nature and inner tube has a clot on its walls. Lubrication approach is used to simplify the problem. Close form solutions are determined for temperature and velocity profile. Impact of related parameters on pressure rise, pressure gradient, velocity and streamlines are interpreted graphically. Comparison among the pure blood and copper blood is presented and analyzed. One main finding of the considered analysis is that the inclusion of copper nanoparticles enlarges the amplitude of the velocity. Therefore, the considered study plays a dominant role in biomedical applications.

  9. AN EXPERIMENTAL STUDY ON EFFECTS OF THE BETA TOPOGRAPHY ON SURFACE FLOWS IN A ROTATING ANNULUS SUBJECT TO RADIAL TEMPERATURE GRADIENT

    Institute of Scientific and Technical Information of China (English)

    LIN Shang-jing; WEI Gang; LIU Li-long; LIU Yu-di

    2005-01-01

    Beta effects on surface flows in a rotating annulus with a radial temperature gradient and a sloping bottom were studied experimentally. An azimuthal jet was produced by the action of the Coriolis force in the convective region between the two side walls of the annulus. Propagating velocity and patterns of the baroclinic wave on the surface were obtained by using a frequency-meter and a streak photograph respectively. It is shown that there exists the nonlinear interaction between the baroclinic and beta effects. The beta effect exerts little influence on the stratification flows and constrains the baroclinic instability, and it prompts the instability of the weak stratification flows and results in the surface pattern of waves with higher frequency. It is also indicated that the beta effect can reduce the propagating speed of the surface waves in the jet, and increase the thermal Rossby number for those same surface patterns under a given Taylor number.

  10. [A case report of aortic valvuloplasty by rasping technique for aortic stenosis with small annulus simultaneously performed with mitral valve replacement].

    Science.gov (United States)

    Taniyasu, N; Kou, E; Hiramatsu, T; Yokoyama, S; Takenaka, A; Ikawa, O

    1997-02-01

    The patient was a 48-year-old woman with aortic stenosis and regurgitation and mitral stenosis. Preoperative cardiac catheterization revealed LV-Ao pressure gradient of 30 mmHg and regurgitation of Sellers III. The aortic annulus was measured less than 19 mm. As operative findings, the aortic annulus seemed to be too small to be replaced with 19 mm prosthetic valve. Aortic valvuloplasty (AVP) with rasping technique was performed for the aortic valve and valve replacement was carried out for the mitral valve. After aortic declamping and occurring her beat, the transesophageal echocardiographic evaluation for AVP was effective. Postoperative course was uneventful. Postoperative cardiac catheterization have shown decreased transvalvular pressure gradient up to 10 mmHg and aortic regurgitation of Sellers I.

  11. Inspection and Gamma-Ray Dose Rate Measurements of the Annulus of the VSC-17 Concrete Spent Nuclear Fuel Storage Cask

    Energy Technology Data Exchange (ETDEWEB)

    P. L. Winston

    2007-09-01

    The air cooling annulus of the Ventilated Storage Cask (VSC)-17 spent fuel storage cask was inspected using a Toshiba 7 mm (1/4”) CCD video camera. The dose rates observed in the annular space were measured to provide a reference for the activity to which the camera(s) being tested were being exposed. No gross degradation, pitting, or general corrosion was observed.

  12. Performance of transonic fan stage with weight flow per unit annulus area of 208 kilograms per second per square meter (42.6 (lb/sec)/sq ft)

    Science.gov (United States)

    Urasek, D. C.; Kovich, G.; Moore, R. D.

    1973-01-01

    Performance was obtained for a 50-cm-diameter compressor designed for a high weight flow per unit annulus area of 208 (kg/sec)/sq m. Peak efficiency values of 0.83 and 0.79 were obtained for the rotor and stage, respectively. The stall margin for the stage was 23 percent, based on equivalent weight flow and total-pressure ratio at peak efficiency and stall.

  13. Effect of Thermo-Diffusion and Chemical Reaction on Mixed Convective Heat And Mass Transfer Through A Porous Medium In Cylindrical Annulus With Heat Source.

    Directory of Open Access Journals (Sweden)

    Dr.K.Gnaneswar

    2014-09-01

    Full Text Available A finite element study of combined heat and mass transfer flow through a porous medium in a circular cylindrical annulus with Soret and Dufour effects in the presence of heat sources has been analyzed. The coupled velocity, energy, and diffusion equations are solved numerically by using Galerkin- finite element technique. Shear stress, Nusslet number and Sherwood number are evaluated numerically for different values of the governing parameters under consideration and are shown in tabular form.

  14. CT-angiography-based evaluation of the aortic annulus for prosthesis sizing in transcatheter aortic valve implantation (TAVI-predictive value and optimal thresholds for major anatomic parameters.

    Directory of Open Access Journals (Sweden)

    Florian Schwarz

    Full Text Available BACKGROUND/OBJECTIVES: To evaluate the predictive value of CT-derived measurements of the aortic annulus for prosthesis sizing in transcatheter aortic valve implantation (TAVI and to calculate optimal cutoff values for the selection of various prosthesis sizes. METHODS: The local IRB waived approval for this single-center retrospective analysis. Of 441 consecutive TAVI-patients, 90 were excluded (death within 30 days: 13; more than mild aortic regurgitation: 10; other reasons: 67. In the remaining 351 patients, the CoreValve (Medtronic and the Edwards Sapien XT valve (Edwards Lifesciences were implanted in 235 and 116 patients. Optimal prosthesis size was determined during TAVI by inflation of a balloon catheter at the aortic annulus. All patients had undergone CT-angiography of the heart or body trunk prior to TAVI. Using these datasets, the diameter of the long and short axis as well as the circumference and the area of the aortic annulus were measured. Multi-Class Receiver-Operator-Curve analyses were used to determine the predictive value of all variables and to define optimal cutoff-values. RESULTS: Differences between patients who underwent implantation of the small, medium or large prosthesis were significant for all except the large vs. medium CoreValve (all p's<0.05. Furthermore, mean diameter, annulus area and circumference had equally high predictive value for prosthesis size for both manufacturers (multi-class AUC's: 0.80, 0.88, 0.91, 0.88, 0.88, 0.89. Using the calculated optimal cutoff-values, prosthesis size is predicted correctly in 85% of cases. CONCLUSION: CT-based aortic root measurements permit excellent prediction of the prosthesis size considered optimal during TAVI.

  15. Iterative Learning of Transcatheter Mitral Valve Replacement in Mitral Valve Annulus Calcification: Management and Prevention of Transcatheter Mitral Valve Replacement Dislocation.

    Science.gov (United States)

    Hulman, Michal; Bena, Martin; Artemiou, Panagiotis; Gasparovic, Ivo; Hudec, Vladan; Rajani, Ronak; Bapat, Vinayak

    2016-10-01

    Transcatheter mitral valve replacement using balloon-expandable valves is an emerging technique for the treatment of patients with significant mitral regurgitation who have been judged to be inoperable owing to significant mitral valve annulus calcification. Although initial reports have been promising, there remains a lack of consensus as to how to plan for transcatheter mitral valve replacement deployment in terms of appropriateness, sizing, and positioning to mitigate the risks of valve displacement and paravalvular regurgitation. We describe two cases of transcatheter mitral valve replacement in patients with significant mitral valve annulus calcification. The first was complicated by valve displacement into the left atrium, which was successfully managed by surgical redeployment and fixation. The second case was thereafter performed successfully using iterative learning and the application of specific preprocedural planning techniques acquired from a root cause analysis of the first case. We describe our experience with both cases and the specific planning principles required to prevent transcatheter mitral valve replacement displacement in patients with mitral valve annulus calcification.

  16. Use of the Konno procedure in an 80-year-old woman with aortic stenosis, a narrow left ventricular outflow tract, and a small aortic annulus.

    Science.gov (United States)

    Misumi, Hiroyasu; Katayama, Yukihiro; Takaji, Kentaro; Oshitomi, Takashi; Uesugi, Hideyuki; Hirayama, Touitsu; Takeuchi, Takamasa

    2014-01-01

    This report describes a technique for repairing an aortic stenosis in an elderly patient with a small aortic annulus and a narrow left ventricular outflow tract. Preoperative echocardiography in an 80-year-old woman showed severe aortic stenosis with a narrow outflow tract: the aortic valve area was 0.48 cm(2), the aortic annular diameter was 14 mm, and the left ventricular outflow tract diameter was 14 mm. The Konno procedure was used to enlarge both the small aortic annulus and the left ventricular outflow tract, and a 19-mm Carpentier-Edwards bioprosthetic valve was implanted. The patient's postoperative course was uneventful. The left ventricular mass decreased from a preoperative value of 236 g to 96 g, 3 years after surgery. Only a few reports have described the use of the Konno operation in adult patients. In the present case, the Konno operation was demonstrated to be a good option for aortic stenosis accompanied by a small aortic annulus and a narrow left ventricular outflow tract, even in an elderly patient.

  17. Numerical Study of Laminar Forced Convection of Water/Al2o3 Nanofluid in an Annulus with Constant Wall Temperature

    Directory of Open Access Journals (Sweden)

    Amin Kashani

    2013-04-01

    Full Text Available Laminar forced convection of a nanofluid consisting of water and Al2O3 in a horizontal annulus has been studied numerically. Two-phase mixture model has been used to investigate thermal behaviors of the nanofluid over constant temperature thermal boundary condition and with different volume concentration of nanoparticles. Comparisons with previously published experimental and analytical works on flow behavior in horizontal annulus show good agreements between the results as volume fraction is zero. In general convective heat transfer coefficient increases with nanoparticle concentration. ABSTRAK: Kertaskerja ini mengkaji secara numerik olakan paksa bendalir lamina yang menganduangi air dan Al2O3 didalam anulus mendatar. Model campuran dua fasa digunakan bagi mengkaji tingkah laku haba bendalir nano pada keadaan suhu malar dengan kepekatan nanopartikel berbeza. Perbandingan dengan karya eksperimen dan analitikal yang telah diterbitkan menunjukkan bahawa kelakuan aliran didalm anulus mendatar adalah baik apabila pecahan isipadu adalah sifar. Pada amnya, pekali pemindahan haba olakan meningkat dengan kepekatan nanopartikel. KEYWORDS: nanofluid; volume concentration; heat transfer enhancement; laminar flow convection; annulus

  18. Inclusion of Zinc Oxide Nanoparticles into Virus-Like Peptide Nanocapsules Self-Assembled from Viral β-Annulus Peptide

    Directory of Open Access Journals (Sweden)

    Seiya Fujita

    2014-09-01

    Full Text Available A viral β-annulus peptide connected with a zinc oxide (ZnO-binding sequence (HCVAHR at its N-terminal was synthesized, and the inclusion behavior of quantum-sized ZnO nanoparticles into the peptide nanocapsules formed by self-assembly of the peptide in water was investigated. Dynamic light scattering (DLS measurements showed that ZnO nanoparticles (approximately 10 nm in the presence of the peptide (0.1 mM formed assemblies with an average size of 48 ± 24 nm, whereas ZnO nanoparticles in the absence of the peptide formed large aggregates. Transmission electron microscopy (TEM observations of the ZnO nanoparticles in the presence of the peptide revealed that ZnO nanoparticles were encapsulated into the peptide nanocapsules with a size of approximately 50 nm. Fluorescence spectra of a mixture of the peptide and ZnO nanoparticles suggested that the ZnO surface and the peptide interact. Template synthesis of ZnO nanoparticles with the peptide nanocapsules afforded larger nanoparticles (approximately 40 nm, which are not quantum-sized ZnO.

  19. Calculation Analysis of Pressure Wave Velocity in Gas and Drilling Mud Two-Phase Fluid in Annulus during Drilling Operations

    Directory of Open Access Journals (Sweden)

    Yuanhua Lin

    2013-01-01

    Full Text Available Investigation of propagation characteristics of a pressure wave is of great significance to the solution of the transient pressure problem caused by unsteady operations during management pressure drilling operations. With consideration of the important factors such as virtual mass force, drag force, angular frequency, gas influx rate, pressure, temperature, and well depth, a united wave velocity model has been proposed based on pressure gradient equations in drilling operations, gas-liquid two-fluid model, the gas-drilling mud equations of state, and small perturbation theory. Solved by adopting the Runge-Kutta method, calculation results indicate that the wave velocity and void fraction have different values with respect to well depth. In the annulus, the drop of pressure causes an increase in void fraction along the flow direction. The void fraction increases first slightly and then sharply; correspondingly the wave velocity first gradually decreases and then slightly increases. In general, the wave velocity tends to increase with the increase in back pressure and the decrease of gas influx rate and angular frequency, significantly in low range. Taking the virtual mass force into account, the dispersion characteristic of the pressure wave weakens obviously, especially at the position close to the wellhead.

  20. Transient critical heat flux under flow coast-down in vertical annulus with non-uniform heat flux distribution

    Energy Technology Data Exchange (ETDEWEB)

    Moon, S.K.; Chun, S.Y.; Choi, K.Y.; Yang, S.K. [Korea Atomic Energy Research Inst., Taejon (Korea, Republic of)

    2001-07-01

    An experimental study on transient critical heat flux (CHF) under flow coast-down has been performed for water flow in a non-uniformly heated vertical annulus under low flow and a wide range of pressure conditions. The objectives of this study are to systematically investigate the effect of the flow transient on the CHF and to compare the transient CHF with steady state CHF. The transient CHF experiments have been performed for three kinds of flow transient modes based on the coast-down data of the Kori 3/4 nuclear power plant reactor coolant pump. Most of the CHFs occurred in the annular-mist flow regime. Thus, it means that the possible CHF mechanism might be the liquid film dryout in the annular-mist flow regime. For flow transient mode with the smallest flow reduction rate, the time-to-CHF is the largest. At the same inlet subcooling, system pressure and heat flux, the effect of the initial mass flux on the critical mass flux can be negligible. However, the effect of the initial mass flux on the time-to-CHF becomes large as the heat flux decreases. Usually, the critical mass flux is large for slow flow reduction. There is a pressure effect on the ratio of the transient CHF data to steady state CHF data. Some conventional correlations show relatively better CHF prediction results for high system pressure, high quality and slow transient modes than for low system pressure, low quality and fast transient modes. (author)

  1. A Novel Dynamic Model for Predicting Pressure Wave Velocity in Four-Phase Fluid Flowing along the Drilling Annulus

    Directory of Open Access Journals (Sweden)

    Xiangwei Kong

    2015-01-01

    Full Text Available A dynamic pressure wave velocity model is presented based on momentum equation, mass-balance equation, equation of state, and small perturbation theory. Simultaneously, the drift model was used to analyze the flow characteristics of oil, gas, water, and drilling fluid multiphase flow. In addition, the dynamic model considers the gas dissolution, virtual mass force, drag force, and relative motion of the interphase as well. Finite difference and Newton-Raphson iterative are introduced to the numerical simulation of the dynamic model. The calculation results indicate that the wave velocity is more sensitive to the increase of gas influx rate than the increase of oil/water influx rate. Wave velocity decreases significantly with the increase of gas influx. Influenced by the pressure drop of four-phase fluid flowing along the annulus, wave velocity tends to increase with respect to well depth, contrary to the gradual reduction of gas void fraction at different depths with the increase of backpressure (BP. Analysis also found that the growth of angular frequency will lead to an increase of wave velocity at low range. Comparison with the calculation results without considering virtual mass force demonstrates that the calculated wave velocity is relatively bigger by using the presented model.

  2. Morphology and the expression of connexin 43 and 40 in bundles of transition cells in the adult atrioventricular junction%成人房室交界区过渡细胞束形态学及连接蛋白43和40的表达

    Institute of Scientific and Technical Information of China (English)

    宋慧芳; 吕华; 范益民; 夏仲年; 阎八一; 高雨仁; 杨桂姣

    2011-01-01

    目的 观察临床上心律失常常见发生部位及射频消融治疗靶点部位--房室交界区和邻近区域的形态学特点及连接蛋白(Cx)43和40的表达,为心律失常发生机制及可能的有效治疗部位提供形态学依据.方法 10例正常成人心脏,选取房室交界区及其邻近部位,常规石蜡包埋,HE、Masson染色,选定目标部位行Cx43、Cx40免疫组织化学染色,并进行图像及统计学分析.结果 峡部、冠状窦口周围和远端、二尖瓣纤维环处及与右房瓣上肌环邻近的中心纤维体等处可见较多过渡细胞束走行,并从不同方向与房室结及结后延伸不同部位相连.过渡细胞组成、排布、心肌纤维走行和相互间的联系有别于普通工作心肌.Cx43、Cx40在过渡细胞束1~4及右房瓣上肌环中分布范围小但集中,而在左房近膜部处的过渡细胞中表达较多;峡部Cx43、Cx40表达较集中.结论 房室交界区及其邻近区域存在双(多)径传导的形态学基础,且与目前常用的射频消融治疗心律失常靶点部位具有对应关系.%Objective To observe the morphological feature and the expression of connexin( Cx )43 and Cx40 in the common arrhythmogenesis and radiofrequenc:y ahlation( RFA ) region, the atrioventricular junction and its surrounding area, in order to provide the morphological basis for understanding the mechanism of arrhythmogenesis and possible sites for therapy.Methods Ten fresh normal adult hearts were used in this study.The specimens containing the atrioventricular node( AVN ) was harvested, embedded in paraffin and sectioned.The sections were stained with HE.Masson staining.Expression of Cx43 and Cx40 was examined by immunohistochemistry and image analysis.Results There were the bundles of transition cells at cavo-tricuspid isthmus, around the opening and distal end of coronary sinus, at the annulus fibrosus of bicuspid valve, and at the central fibrous body( CFB ) near the annulus of right

  3. Aortic annulus dimension assessment by computed tomography for transcatheter aortic valve implantation: differences between systole and diastole.

    Science.gov (United States)

    Bertaso, Angela G; Wong, Dennis T L; Liew, Gary Y H; Cunnington, Michael S; Richardson, James D; Thomson, Viji S; Lorraine, Brett; Kourlis, George; Leech, Diana; Worthley, Matthew I; Worthley, Stephen G

    2012-12-01

    Accurate assessment of aortic annular dimensions is essential for successful transcatheter aortic valve implantation (TAVI). Annular dimensions are conventionally measured in mid-systole by multidetector computed tomography (MDCT), echocardiography and angiography. Significant differences in systolic and diastolic aortic annular dimensions have been demonstrated in cohorts without aortic stenosis (AS), but it is unknown whether similar dynamic variation in annular dimensions exists in patients with severe calcific AS in whom aortic compliance is likely to be substantially reduced. We investigated the variation in aortic annular dimensions between systole and diastole in patients with severe calcific AS. Patients with severe calcific AS referred for TAVI were evaluated by 128-slice MDCT. Aortic annular diameter was measured during diastole and systole in the modified coronal, modified sagittal, and basal ring planes (maximal, minimal and mean diameters). Differences between systole and diastole were analysed by paired t test. Fifty-nine patients were included in the analysis. Three of the five aortic dimensions measured increased significantly during systole. The largest change was a 0.75 mm (3.4%) mean increase in the minimal diameter of the basal ring during systole (p = 0.004). This corresponds closely to the modified sagittal view, which also increased by mean 0.42 mm (1.9%) during systole (p = 0.008). There was no significant change in the maximal diameter of the basal ring or the modified coronal view during systole (p > 0.05). There is a small magnitude but statistically significant difference in aortic annulus dimensions of patients with severe AS referred for TAVI when measured in diastole and systole. This small difference is unlikely to alter clinical decisions regarding prosthesis size or suitability for TAVI.

  4. Diagnostic and therapeutic value of intradiscal steroid injection in patients with discogenic low back pain combined with radial fissure of annulus fibrosis%椎间盘封闭术对纤维环破裂型椎间盘源性腰痛的诊治价值

    Institute of Scientific and Technical Information of China (English)

    李永华; 胡子昂; 范顺武; 赵凤东; 赵兴

    2012-01-01

    Objective To retrospectively investigate diagnostic and therapeutic value of intradiscal steroid injection in patients with discogenic low back pain combined with radial fissure of annulus fibrosis.Methods Totally 120 patients who had undergone CT guided intervertebral discography and steroid injections,including 72 males and 48 females,aged from 25 to 60 years (average,48 years),were recruited to this study.According to Dallas discography description system,7 cases were rated as grade 0,36 grade 1,48grade 2,and 29 grade 3.The Visual Analogue Scale (VAS) and Roland Morris Disability Questionnaire (RMDQ) were used to evaluate clinical effect at 2 weeks,2 months,6 months,12 months and 24 months postoperatively.Results Most of patients who underwent steroid injection in single highly suspect "diseased disc" claimed significant symptom improvement.There were statistically significant differences between pre- and post-operative VAS and RMDQ.The clinical effect in grade 3 group was better than those in grade 1 and grade 2 groups,and the differences were significant.Patients with severe disc disruption (grade 3) had a lower recurrence rate of low back pain compared with other patients.Conclusion Intradiseal steroid injection not only can significantly relieve discogenic low back pain,but also can benefit diagnosis of discogenic low back pain,especially in patients who fail to reproduce "concordant pain" on discography.For patients with severe rupture of the annulus fibrosus,the relief of discogenic low back pain is more significant.%目的 探讨椎间盘封闭术对纤维环破裂型椎间盘源性腰痛的诊治价值.方法 临床高度怀疑椎间盘源性腰痛行椎间盘造影及单个椎间盘封闭术且有完整随访资料的患者120例,男72例,女48例;年龄25~60岁,平均48岁.根据造影术中纤维环破裂Dallas分级将患者分为0级组7例、1级组36例、2级组48例、3级组29例.采用疼痛视觉模拟评分(visual analogue scale,VAS)及

  5. Influence of St. Jude medical valve in patients with aortic stenosis and small aortic annulus on cardiac function and late survival result.

    Science.gov (United States)

    Natsuaki, Masafumi; Itoh, Tsuyoshi; Okazaki, Yukio; Takarabe, Kyoumi; Furukawa, Koujirou; Rikitake, Kazuhisa; Ohtubo, Satoshi

    2002-10-01

    This clinical study analyzes our experience of postoperative cardiac function and long-term survival rate in patients with aortic stenosis and small-size St. Jude Medical (SJM) valve. Sixty-eight patients who underwent aortic valve replacement by SJM valve were divided into two groups by preoperative aortic annulus diameter. Group 1 consisted of 44 patients with small aortic annulus and small-size SJM valve (19 mm or 21 mm). In Group 1, small SJM standard valves were implanted in 16 patients, and small SJM Hemodynamic Plus (HP) valves were implanted in 28 patients. Group 2 consisted of 24 patients with large-size SJM standard valve (23 mm or larger). Preoperative left ventricular mass index, left ventricular dimension, the dimension of ascending aorta, and body surface area were significantly smaller in Group 1 than in Group 2. Average age at surgery was older in Group 1 than in Group 2. Effective orifice area index of the SJM valve measured by the manufacturer's data was smaller in Group 1 than in Group 2. Postoperative left ventricular mass indexes of Group 1 (standard valve or HP valve) and Group 2 significantly decreased in comparison with the preoperative mass indexes. Postoperative left ventricular ejection fraction and the peak ejection rate of Group 1 were not different from those of Group 2. The 10 year survival rate of Group 1 was 79%, and the rate of Group 2 was 77%. At 10 years after surgery, freedom from valve-related complication of Group 1 was 80%, and freedom from complication of Group 2 was 81%. Our results demonstrated that small-size SJM valve afforded satisfactory long-term survival rate and valve-related event-free rate for elderly patients with small body surface area and small aortic annulus.

  6. AN EXPERIMENTAL STUDY ON THREE-DIMENSIONAL STRUCTURE OF BAROCLINIC WAVY JET STREAM IN A ROTATING ANNULUS SUBJECT TO RADIAL TEMPERATURE GRADIENT

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Three-dimensional structure of baroclinic wavy jet was experimentally studied in rotating annulus subject to a negative radial temperature gradient.General features of wavy surface jet in the system were obtained.Based on the precise measurements of velocity distribution of the jet with LDV and the three-dimensional temperature field in the convective system, three-dimensional thermodynamic structures of jet were gained, and by using a correlation of three-dimensional disturbed temperature, the unstable mechanism of disturbed temperature of baroclinic fluid in a rotating system was further discussed.

  7. Performance of transonic fan stage with weight flow per unit annulus area of 198 kilograms per second per square meter (40.6(lb/sec)/sq ft)

    Science.gov (United States)

    Kovich, G.; Moore, R. D.; Urasek, D. C.

    1973-01-01

    The overall and blade-element performance are presented for an air compressor stage designed to study the effect of weight flow per unit annulus area on efficiency and flow range. At the design speed of 424.8 m/sec the peak efficiency of 0.81 occurred at the design weight flow and a total pressure ratio of 1.56. Design pressure ratio and weight flow were 1.57 and 29.5 kg/sec (65.0 lb/sec), respectively. Stall margin at design speed was 19 percent based on the weight flow and pressure ratio at peak efficiency and at stall.

  8. On the collagen criss-cross angles in the annuli fibrosi of lumbar spine finite element models

    OpenAIRE

    2011-01-01

    In the human lumbar spine, annulus fibrosus fibres largely contribute to intervertebral disc stability. Detailed annulus models are therefore necessary to obtain reliable predictions of lumbar spine mechanics by finite element modelling. However, different definitions of collagen orientations coexist in the literature for healthy human lumbar annuli. Therefore, four annulus fibre-induced anisotropy models were built from reported anatomical descriptions, and inserted in a L3–L5 lumba...

  9. Aortic valve annulus and sinus-tube joint diameters in normal adults of Chinese Han ethnic group

    Institute of Scientific and Technical Information of China (English)

    ZHU Dan; ZHAO Qiang

    2008-01-01

    Background The anatomic value of the aortic root is important for aortic valve repair.This study was to determine the normaI diameters of the aortic valve annulus (AVA) and sinus-tube ioint (STJ) in the healthy adults of Chinese Han ethnic group,and to provide a morphological foundation for potential clinical application.Methods Echocardiography was performed in 326 normal subjects,who were divided into 5 groups according to their age.The diameters of the AVA and STJ were measured in the parasternal long-axis view.and normalized to body surface area (BSA).They were averaged for each age group and for each gender.Differences were then determined between the normalized diameters for each age group and for both genders.Pearson's product-moment correlation coefficient was used to determine the differences between AVA and STJ diameters.It was also used to determine any positive or neqative correlations between the above two variables and age,BSA,weight,and height.Results The diameters of the AVA and STJ of Han nationality patients increased with an increase in age,BSA,weight,and height.The correlation coefficient between AVA diameter and BSA was 0.4944 (P<0.0001),between AVA diameter and age,0.1138 (P<0.05),between AVA diameter and weight,0.4521 (P<0.001),and between AVAdiameter and height,0.471 3 (P<0.001).The correlation coefficient between STJ diameter and BSA was 0.3910 (P<0.0001),between STJ diameter and age,0.3667 (P<0.0001),between STJ diameter and weight,0.4586 (P<0.0001),and between STJ diameter and height,0.3736 (P<0.0001).The difference between the above two diameters was statistically significant at 2.42±2.45 mm (paired t-test:t=-17.25;P<0.0001).AVA and STJ diameters were similar in both genders of each group when indexed to BSAConclusions The diameters of the AVA and STJ of adults of Chinese Han ethnic group increase with age,BSA,weight,and height.The diameters of the AVA and the STJ are similar in both genders.when indexed to BSA

  10. Flows in Concentric Annulus

    Directory of Open Access Journals (Sweden)

    Shuichi Torii

    1998-01-01

    stress turbulence model is employed to determine three normal components of the Reynolds stress and its off-diagonal one. The turbulent heat flux is expressed by Boussinesq approximation in which the eddy diffusivity.for heat is given as functions of the temperature variance t2¯ and the dissipation rate of temperate fluctuations εt. The governing boundarylayer equations are discretized by means of a control volume finite-difference technique and numerically solved using the marching procedure. An inner core rotation causes an amplification of the three normal components of the Reynolds stress over the whole cross section, resulting in a substantial enhancement in the Nusselt number.

  11. Fresh Autologous Pericardium to Reconstruct the Pulmonary Valve at the Annulus When Tetralogy of Fallot Requires a Transannular Patch at Midterm.

    Science.gov (United States)

    Pande, Shantanu; Sharma, Jugal K; Siddartha, C R; Bansal, Anubhav; Agarwal, Surendra K; Tewari, Prabhat; Kapoor, Aditya

    2016-06-01

    Tetralogy of Fallot often requires reconstruction of the right ventricular outflow tract with a transannular patch (TAP), but this renders the pulmonary valve incompetent and eventually leads to right ventricular dysfunction. We retrospectively evaluated the efficacy of a reconstructed pulmonary valve and annulus in 70 patients who underwent, from December 2006 through December 2010, complete correction of tetralogy of Fallot. We divided the 70 patients into 2 groups in accordance with whether they required (n=50) or did not require (n=20) a TAP. We used autologous untreated pericardium to fashion the TAP and to create both an annulus of the correct size and a competent pulmonary valve with native leaflets. We evaluated the efficiency of this procedure both functionally and anatomically. The median age of the patients was 11 years (range, 2-38 yr). There were 56 males, with no significant difference in sexual distribution between groups. The clinical follow-up was 88% for 57.5 months, and the echocardiographic follow-up was 80% for 36 months. There was no significant difference in outflow gradient or in the occurrence of pulmonary insufficiency between the TAP group (none, 31; mild, 12; moderate, 6; and severe, 1) and the No-TAP group (none, 16; moderate, 2; and severe, 2) (P=0.59). Nor was there any thickening or calcification in the constructed valves. We conclude that pulmonary valves constructed of untreated autologous pericardium performed as well as native valves after total tetralogy of Fallot correction at midterm.

  12. Mid-term results of small-sized St. Jude Medical Regent prosthetic valves (21 mm or less) for small aortic annulus.

    Science.gov (United States)

    Mizoguchi, Hiroki; Sakaki, Masayuki; Inoue, Kazushige; Iwata, Takashi; Tei, Keikou; Miura, Takuya

    2013-11-01

    Prosthesis-patient mismatch (PPM) is always of concern when performing aortic valve replacement (AVR) in patients with a small aortic annulus. Although bioprosthetic AVR is preferred in patients older than 65 years, we have experienced cases in elderly patients with a small aortic annulus whereby we could not implant small-sized bioprosthetic valves. We have implanted St. Jude Medical Regent (SJMR) mechanical valves (St. Jude Medical, St. Paul, MN, USA) as necessary, even in elderly patients with no aortic annulus enlargement. We investigated our experiences of AVR with SJMR mechanical valves of 21 mm or less in size. Between January 2006 and December 2009, 40 patients underwent AVR with SJMR mechanical valves ≤21 mm in size: 9 patients received 21-mm valves, 19 received 19-mm valves, and 12 received 17-mm valves. The mean age was 65.9 ± 9.5 years, and 25 patients (62.5 %) were 65 years or older. We evaluated the clinical outcome and the echocardiographic data for each valve size. There was no operative or hospital mortality. The mean duration of clinical follow-up was 31.2 ± 17.6 months. During follow-up, there were no hospitalizations due to heart failure. The cumulative valve-related event-free survival was 93 % at 33 months, and the cumulative hemorrhagic event-free survival was 93 % at 33 months and 84 % at 43 months, using the Kaplan-Meier method. At follow-up, the mean values of the measured effective orifice area (EOA) for the 21-, 19-, and 17-mm prostheses were 2.00 ± 0.22, 1.74 ± 0.37, and 1.25 ± 0.26 cm(2), and the mean measured EOA index (EOAI) were 1.17 ± 0.12, 1.11 ± 0.21 and 0.90 ± 0.22 cm(2)/m(2), respectively. A PPM (EOAI ≤0.85) was documented in 5 patients, all of whom had received a 17-mm SJMR valve. AVR with SJMR valves of 21 mm or less in size appears to show satisfactory clinical and hemodynamic results.

  13. Long-term Mortality Predictors in Patients with Small Aortic Annulus Undergoing Aortic Valve Replacement with a 19- or 21-mm Bioprosthesis

    Directory of Open Access Journals (Sweden)

    Jenny Lourdes Rivas de Oliveira

    Full Text Available Abstract Introduction: Replacement of the aortic valve in patients with a small aortic annulus is associated with increased morbidity and mortality. A prosthesis-patient mismatch is one of the main problems associated with failed valves in this patient population. Objective: To evaluate the long-term mortality predictors in patients with a small aortic annulus undergoing aortic valve replacement with a bioprosthesis. Methods: In this retrospective observational study, a total of 101 patients undergoing aortic valve replacement from January 2000 to December 2010 were studied. There were 81 (80.19% women with a mean age of 52.81±18.4 years. Severe aortic stenosis was the main indication for surgery in 54 (53.4% patients. Posterior annulus enlargement was performed in 16 (15.8% patients. Overall, 54 (53.41% patients underwent concomitant surgery: 28 (27.5% underwent mitral valve replacement, and 13 (12.7% underwent coronary artery bypass graft surgery. Results: Mean valve index was 0.82±0.08 cm2/m2. Overall, 17 (16.83% patients had a valve index lower than 0.75 cm2/m2, without statistical significance for mortality (P=0.12. The overall 10-year survival rate was 83.17%. The rate for patients who underwent isolated aortic valve replacement was 91.3% and 73.1% (P=0.02 for patients who underwent concomitant surgery. In the univariate analysis, the main predictors of mortality were preoperative ejection fraction (P=0.02; HR 0.01 and EuroSCORE II results (P=0.00000042; HR 1.13. In the multivariate analysis, the main predictors of mortality were age (P=0.01, HR 1.04 and concomitant surgery (P=0.01, HR 5.04. Those relationships were statistically significant. Conclusion: A valve index of < 0.75 cm2/m2 did not affect 10-year survival. However, concomitant surgery and age significantly affected mortality.

  14. Growth factor expression in degenerated intervertebral disc tissue. An immunohistochemical analysis of transforming growth factor beta, fibroblast growth factor and platelet-derived growth factor.

    Science.gov (United States)

    Tolonen, Jukka; Grönblad, Mats; Vanharanta, Heikki; Virri, Johanna; Guyer, Richard D; Rytömaa, Tapio; Karaharju, Erkki O

    2006-05-01

    Degenerated intervertebral disc has lost its normal architecture, and there are changes both in the nuclear and annular parts of the disc. Changes in cell shape, especially in the annulus fibrosus, have been reported. During degeneration the cells become more rounded, chondrocyte-like, whereas in the normal condition annular cells are more spindle shaped. These chondrocyte-like cells, often forming clusters, affect extracellular matrix turnover. In previous studies transforming growth factor beta (TGFbeta) -1 and -2, basic fibroblast growth factor (bFGF) and platelet-derived growth factor (PDGF) have been highlighted in herniated intervertebral disc tissue. In the present study the same growth factors are analysed immunohistochemically in degenerated intervertebral disc tissue. Disc material was obtained from 16 discs operated for painful degenerative disc disease. Discs were classified according to the Dallas Discogram Description. Different disc regions were analysed in parallel. As normal control disc tissue material from eight organ donors was used. Polyclonal antibodies against different growth factors and TGFbeta receptor type II were used, and the immunoreaction was detected by the avidin biotin complex method. All studied degenerated discs showed immunoreactivity for TGFbeta receptor type II and bFGF. Fifteen of 16 discs were immunopositive for TGFbeta-1 and -2, respectively, and none showed immunoreaction for PDGF. Immunopositivity was located in blood vessels and in disc cells. In the nucleus pulposus the immunoreaction was located almost exclusively in chondrocyte-like disc cells, whereas in the annular region this reaction was either in chondrocyte-like disc cells, often forming clusters, or in fibroblast-like disc cells. Chondrocyte-like disc cells were especially prevalent in the posterior disrupted area. In the anterior area of the annulus fibrosus the distribution was more even between these two cell types. bFGF was expressed in the anterior annulus

  15. Toeplitz operators on Dirichlet space Dp on annulus%圆环的 Dirichlet 空间Dp上的 Toeplitz 算子

    Institute of Scientific and Technical Information of China (English)

    梁颖志; 王晓峰

    2014-01-01

    主要研究了圆环M的Dirichlet空间D p (1<p<∞)上Toeplitz算子的有界性、紧性和Fredholm性质,计算了D p ( M)上Toeplitz算子的Fredholm指标,并刻画了D p ( M)上Hankel算子的紧性。%In this paper ,the boundedness ,compactness and the Fredholm properties of Toeplitz operators on the Dirichlet space Dp(M)(1annulus in complex plane are discussed ,and the Fredholm indices of Toeplitz operators on the Dirichlet space Dp(M) are computed .We also describe the compactness of Hankel operators on the Dirichlet space Dp(M).

  16. Valve replacement plus reconstruction of the annulus%瓣环结构重建的瓣膜置换手术

    Institute of Scientific and Technical Information of China (English)

    韩林; 徐志云; 邹良建; 王志农; 王军; 张冠鑫

    2011-01-01

    Objective To investigate the surgical technique and clinical outcomes of reconstruction of the annulus and the intervalvular fibrous body during valve replacements. Methods Fifty-nine patients underwent reconstruction of the annulus or the intervalvular fibrous body during the valve replacement. Indications for the operation were small aortic annulus which may cause patient/prosthesis mismatch in 43, active infective endocarditis with the abscess in the periannulus tissue in 13, extensive calcification of the aortic annulus in 2 and an active bleeding complication of the aortic root after aortic and mitral valve replacement in 1. The reconstruction was done with fresh autologous pericardium. Results The aortic clamping time in reconstruction of the intervalvular fibrous body with double valve replacement was longer than that of the regular double valve replacement. Four patients died in the perioperative period, giving an overall in- hospital mortality of 6.7%. Postoperative complication were: re-sternotomy for bleeding in 2, Ⅲ degree A-V block in 2, respiratory dysfunction in 2, and acute renal failure in 2. Patients were followed up for 6 months by echocardiography study, and no periannular leakage was found. Conclusion Reconstruction of the annulus is an effective technique for patients with a small aortic annulus, extensive calcification of the interventricular fibrous body and active infective endocarditis with abscess. Although the operative procedure is challenging and taking more time, the technique is safe and reproducible.%目的 总结瓣环结构重建的瓣膜置换手术技术及临床效果.方法 2003年1月至2009年5月59例病人行瓣环结构重建的瓣膜置换手术,其中细小主动脉根部43例,感染性心内膜炎累及瓣环结构13例,钙化性主动脉瓣病变钙化斑累及主动脉瓣环2例,主动脉瓣二尖瓣置换手术后主动脉根部出血1例.行主动脉瓣环重建加主动脉瓣置换术40例,二尖瓣

  17. Prediction of Core-Annulus Solids Mass Transfer Coefficient in Gas-Solid Fluidized Bed Risers%气固循环流化床提升管环核区颗粒质量传递系数的估计

    Institute of Scientific and Technical Information of China (English)

    刘新华; 高士秋; 宋文立

    2005-01-01

    Based on analysis of energy dissipation in the core region of gas-solid fluidized bed risers, a simplified model for determination of core-annulus solids mass transfer coefficient was developed according to turbulent diffusion mechanism of particles. The simulation results are consistent with published experimental data. Core-annulus solids mass transfer coefficient decreases with increasing particle size, particle density and solids circulation rate,but generally increases with increasing superficial gas velocity and riser diameter. In the upper dilute region of gas-solid fluidized bed risers, core-annulus solids mass transfer coefficient was found to change little with the axial coordinate in the bed.

  18. Cross-sectional void fraction distribution measurements in a vertical annulus two-phase flow by high speed X-ray computed tomography and real-time neutron radiography techniques

    Energy Technology Data Exchange (ETDEWEB)

    Harvel, G.D. [McMaster Univ., Ontario (Canada)]|[Combustion and Heat Transfer Lab., Takasago (Japan); Hori, K.; Kawanishi, K. [Combustion and Heat Transfer Lab., Takasago (Japan)] [and others

    1995-09-01

    A Real-Time Neutron Radiography (RTNR) system and a high speed X-ray Computed tomography (X-CT) system are compared for measurement of two-phase flow. Each system is used to determine the flow regime, and the void fraction distribution in a vertical annulus flow channel. A standard optical video system is also used to observe the flow regime. The annulus flow channel is operated as a bubble column and measurements obtained for gas flow rates from 0.0 to 30.01/min. The flow regimes observed by all three measurement systems through image analysis shows that the two-dimensional void fraction distribution can be obtained. The X-CT system is shown to have a superior temporal resolution capable of resolving the void fraction distribution in an (r,{theta}) plane in 33.0 ms. Void fraction distribution for bubbly flow and slug flow is determined.

  19. First-in-man transcatheter aortic valve implantation of a 20-mm Edwards SAPIEN XT valve: one step forward for the treatment of patients with severe aortic stenosis and small aortic annulus.

    Science.gov (United States)

    Rodés-Cabau, Josep; DeLarochellière, Robert; Dumont, Eric

    2012-04-01

    We present the case of an 85-year-old woman diagnosed with severe aortic stenosis, porcelain aorta, and a small aortic annulus (17.3 mm), who underwent successful transfemoral transcatheter aortic valve implantation (TAVI) with a 20-mm Edwards SAPIEN XT valve using the NovaFlex+ delivery system. At 1-month follow-up the patient was in NYHA functional class I, and Doppler echocardiography showed a mean residual gradient of 15 mm Hg and trivial paravalvular aortic regurgitation. This case, which shows for the first time the feasibility of TAVI with a 20-mm valve, opens a new avenue for the challenging treatment of patients with aortic stenosis and a small aortic annulus.

  20. The Effects of Platelet-Rich Plasma on Halting the Progression in Porcine Intervertebral Disc Degeneration.

    Science.gov (United States)

    Cho, Hongsik; Holt, David C; Smith, Richard; Kim, Song-Ja; Gardocki, Raymond J; Hasty, Karen A

    2016-02-01

    Disc degeneration and the subsequent herniation and/or rupture of the intervertebral disc (IVD) are due to a failure of the extracellular matrix of the annulus to contain the contents of the nucleus. This results from inadequate maintenance of the matrix components as well as the proteolytic activity of matrix metalloproteinases (MMPs) that degrade matrix molecules. Arresting progression of disc degeneration in the annulus holds greater clinical potential at this point than prevention of its onset in the nucleus. Therefore, in this study, we have therapeutic aims that would decrease levels of the cytokines and growth factors that indirectly lead to disc degeneration via stimulating MMP and increase levels of several beneficial growth factors, such as transforming growth factor-β, with the addition of platelet-rich plasma (PRP) that would stimulate cell growth and matrix synthesis. For this study, we attempted to address these imbalances of metabolism by using tumor necrosis factor-α treated annulus fibrosus cells isolated from porcine IVD tissue and incubating the cells in a growth factor rich environment with PRP. These results indicate that the PRP in vitro increased the production of the major matrix components (type II collagen and aggrecan) and decreased the inhibitory collagenase MMP-1. This application will address a therapeutic approach for intervening early in the degenerative process.

  1. Systolic mitral annulus velocity is a sensitive index for changes in left ventricular systolic function during inotropic therapy in patients with acute heart failure.

    Science.gov (United States)

    Husebye, Trygve; Eritsland, Jan; Bjørnerheim, Reidar; Andersen, Geir Ø

    2017-01-01

    Echocardiography is recommended for assessment of left ventricular systolic function in patients with acute heart failure but few randomised trials have validated techniques like tissue Doppler (TDI) and speckle tracking (STE) in patients with acute heart failure following ST-elevation myocardial infarction. This was a substudy from the LEAF (LEvosimendan in Acute heart Failure following myocardial infarction) trial (NCT00324766 ), which randomised 61 patients developing acute heart failure, including cardiogenic shock, within 48 hours after ST-elevation myocardial infarction, double-blind to a 25-hour infusion of levosimendan or placebo. TDI-derived systolic mitral annulus velocity (S'), STE-derived global longitudinal strain (Sl) and strain rate (SRl) were measured at baseline, day 1, day 5 and after 42 days. Datasets rejected for analyses were 2% (TDI) and 17% (STE). S' increased by 23% in the levosimendan group versus 8% in the placebo group from baseline to day 1 ( p= 0.011) and by 30% vs. 3% from baseline to day 5 ( p sensitive indices for changes in left ventricular systolic function related to treatment with levosimendan. However, S' by TDI was more feasible and sensitive and might be preferred for assessment of changes in left ventricular systolic function in critically ill patients with acute heart failure receiving inotropic therapy.

  2. Non-Hermitian random matrix theory: summation of planar diagrams, the 'single-ring' theorem and the disc-annulus phase transition

    Energy Technology Data Exchange (ETDEWEB)

    Feinberg, Joshua [Physics Department, University of Haifa at Oranim, Tivon 36006 (Israel); Physics Department, Technion, Israel Institute of Technology, Haifa 32000 (Israel)

    2006-08-11

    I review aspects of work done in collaboration with A Zee and R Scalettar (1997 Nucl. Phys. B 504 579; 1997 Nucl. Phys. B 501 643; 2001 J. Math. Phys. 42 5718) on complex non-Hermitian random matrices. I open by explaining why the bag of tools used regularly in analysing Hermitian random matrices cannot be applied directly to analyse non-Hermitian matrices, and then introduce the method of Hermitization, which solves this problem. Then, for rotationally invariant ensembles, I derive a master equation for the average density of eigenvalues in the complex plane, in the limit of infinitely large matrices. This is achieved by resumming all the planar diagrams which appear in the perturbative expansion of the Hermitized Green function. Remarkably, this resummation can be carried out explicitly for any rotationally invariant ensemble. I prove that in the limit of infinitely large matrices, the shape of the eigenvalue distribution is either a disc or an annulus. This is the celebrated 'single-ring' theorem. Which of these shapes is realized is determined by the parameters (coupling constants) which determine the ensemble. By varying these parameters a phase transition may occur between the two possible shapes. I briefly discuss the universal features of this transition. As the analysis of this problem relies heavily on summation of planar Feynman diagrams, I make a special effort at presenting a pedagogical exposition of the diagrammatic method, which some readers may find useful.

  3. MHD mixed convection in a vertical annulus filled with Al{sub 2}O{sub 3}–water nanofluid considering nanoparticle migration

    Energy Technology Data Exchange (ETDEWEB)

    Malvandi, A., E-mail: amirmalvandi@aut.ac.ir [Department of Mechanical Engineering, Neyshabur Branch, Islamic Azad University, Neyshabur (Iran, Islamic Republic of); Safaei, M.R. [Young Researchers and Elite Club, Mashhad Branch, Islamic Azad University, Mashhad (Iran, Islamic Republic of); Kaffash, M.H. [Department of Mechanical Engineering, Neyshabur Branch, Islamic Azad University, Neyshabur (Iran, Islamic Republic of); Ganji, D.D. [Mechanical Engineering Department, Babol University of Technology, Babol (Iran, Islamic Republic of)

    2015-05-15

    In the current study, an MHD mixed convection of alumina/water nanofluid inside a vertical annular pipe is investigated theoretically. The model used for the nanofluid mixture involves Brownian motion and thermophoretic diffusivities in order to take into account the effects of nanoparticle migration. Since the thermophoresis is the main mechanism of the nanoparticle migration, different temperature gradients have been imposed using the asymmetric heating. Considering hydrodynamically and thermally fully developed flow, the governing equations have been reduced to two-point ordinary boundary value differential equations and they have been solved numerically. It is revealed that the imposed thermal asymmetry would change the direction of nanoparticle migration and distorts the velocity, temperature and nanoparticle concentration profiles. Moreover, it is shown that the advantage of nanofluids in heat transfer enhancement is reduced in the presence of a magnetic field. - Highlights: • MHD mixed convection of alumina/water nanofluid inside a vertical annulus. • The effects of nanoparticle migration on rheological and thermophysical characteristics. • The effects of asymmetric heating on nanoparticle migration. • The effects of asymmetric heating on the heat transfer enhancement. • Inclusion of nanoparticles in presence of a magnetic field has a negative effect on performance.

  4. Experimental study on inhibitory effect of niacinamide on tumor necrosis factor-alpha-induced matrix degradation of annulus fibrous tissue in vitro.

    Science.gov (United States)

    Xu, Runbing; Shao, Zengwu; Xiong, Liming

    2008-10-01

    The inhibitory effect of niacinamide on tumor necrosis factor-alpha (TNF-alpha) induced annulus fibrous (AF) degradation was assessed, and the mechanism of the inhibition was investigated. Chiba's intervertebral disc (IVD) culture model was established. Forty-eight IVDs from 12 adult Japanese white rabbits were randomly divided into 4 groups (12 IVDs in each group), and various concentrations of niacinamide and TNF-alpha were added to the medium for intervention: negative control group, niacinamide control group (0.5 mg/mL niacinamide), degeneration group (10 ng/mL TNF-alpha), and treatment group (0.5 mg/mL niacinamide and 10 ng/mL TNF-alpha). After one week's culture, AFs were collected for glycosaminoglycan (GS) content measurement, safranin O-fast green staining, and immunohistochemical staining for type I, II collagen and cysteine containing aspartate specific protease-3 (Caspase-3). It was found that the GS content in treatment group was increased by about 48% as compared with degeneration group (t=16.93, Pniacinamide control group (t=0.71, P=0.667). Safranine O-fast green staining exhibited higher staining density and better histological structure of AF in the treatment group as compared with the degeneration group. Immunohistochemical staining for both Type I and II collagen demonstrated that lamellar structure and continuity of collagen in treatment group were better reserved than in degeneration group. Positive staining rate of Caspase-3 in AFs of negative control group, niacinamide control group, degeneration group and treatment group was 3.4%, 4.3%, 17.9% and 10.3% respectively. The positive rate in treatment group was significantly lower than in degeneration group (Pniacinamide could effectively alleviate TNF-alpha induced destruction and synthesis inhibition of matrix ingredients in AFs. The inhibition may be related with reduction of expression of Caspase-3. Thus, niacinamide is of potential for IVD degeneration clinical treatment.

  5. Thermal performance of a eutectic mixture of lauric and stearic acids as PCM encapsulated in the annulus of two concentric pipes

    Energy Technology Data Exchange (ETDEWEB)

    Sari, Ahmet [Gaziosmanpasa Univ., Dept. of Chemistry, Tokat (Turkey); Kaygusuz, Kamil [Karadeniz Technical Univ., Dept. of Chemistry, Trabzon (Turkey)

    2002-06-01

    Thermal performance characteristics of a eutectic mixture of lauric and stearic acids as phase change material (PCM) during the melting and solidification processes were determined experimentally in a vertical two concentric pipe-energy storage system. This study deals with three important subjects: The first one is to determine the eutectic composition ratio of the lauric acid (LA) and stearic acid (SA) binary system, and to measure its thermophysical properties by DSC. The second one is to establish the thermal characteristics of the mixture such as total melting and solidification times, the heat transfer modes in melted and solidified PCM, and the effect of Reynolds and Stefan numbers as inlet heat transfer fluid (HTF) conditions on the phase transition behaviors. The final one includes the calculations of the heat transfer coefficients between the outside wall of the HTF pipe and the PCM, and heat fractions during the melting and solidification processes of the mixture, and also the discussion of the effect of inlet HTF parameters on these characteristics. The LA-SA binary system in the mixture ratio of 75.5:24.5 wt % forms a eutectic, which melts at 37 deg C and has a latent heat of 182.7 J g{sup -1}, and, thus, these properties make it an attractive phase change material used for passive solar space heating applications such as building and greenhouse heating with respect to the climate conditions. The experimental results indicated that the mixture encapsulated in the annulus of two concentric pipes has good thermal and heat transfer characteristics during the melting and solidification processes, and it has potential for heat storage in passive solar space heating systems. (Author)

  6. Preliminary evaluation of new intrinsically radiopaque hydrogels for replacing the nucleus pulposus

    NARCIS (Netherlands)

    Boelen, EJH; van Hooy-Corstjens, CSJ; Gijbels, MJJ; Bulstra, SK; van Ooij, A; van Rhijn, LW; Koole, LH

    2006-01-01

    Treatment of early degenerative disc disease can, in some cases, be accomplished through implantation of a synthetic prosthesis for the nucleus pulposus. This treatment is attractive, since the annulus fibrosus-as well as the function of the disc-is preserved. This study reports on two new synthetic

  7. Expression of NGF, Trka and p75 in human cartilage

    Directory of Open Access Journals (Sweden)

    A Gigante

    2009-06-01

    Full Text Available Nerve growth factor (NGF exerts its action through two types of receptor: high-affinity tyrosine kinase A receptor (trkA and low-affinity p75 receptor. NGF has a neurotrophic role in central and peripheral nervous system development, but there is also clear evidence of its involvement in the developing skeleton. The aim of the present immunohistochemical study was to investigate the expression and distribution of NGF, trkA, and p75 in normal cartilaginous tissues from adult subjects: articular and meniscal cartilage of the knee, cartilage from the epiglottis, and intervertebral disc tissue. Detection of NGF mRNA was also performed by in situ hybridization. Immunoreaction for NGF and the two receptors in articular chondrocytes, chondrocyte-like cells of meniscus and annulus fibrosus, and chondrocytes of the epiglottis demonstrated that they are all expressed in hyaline, fibrous and elastic cartilaginous tissues, suggesting that they could be involved in cartilage physio-pathology.

  8. Mathematical model and simulation of pipe-annulus welding assemble surface and opening%管-环相贯焊接装配面及开孔数学模型与仿真

    Institute of Scientific and Technical Information of China (English)

    王强; 徐雷; 彭少峰

    2015-01-01

    针对复杂管-环桁架节点相贯线参数方程求解困难的问题,提出一种基于 Newton 迭代法的求解方式。以圆管和环管的参数方程建立 Newton 迭代函数,利用相贯体之间的几何约束关系,选择合适的迭代初始值,逐次逼近,求解相贯线参数方程的解;推导了管-环相贯焊接装配面实际切割角计算公式;将 Newton 迭代法对骑坐式和插入式两种带钝边坡口的开孔方式进行推广。Newton 迭代法编程简单、收敛速度快,适于复杂相贯体相贯线的求解。对比 Newton 迭代法和实体布尔运算所生成的相贯线,结果表明:Newton 迭代求解法偏差极小,准确性和可靠性好。%Since the parametric equation of complex pipe-annulus truss could not be solved easily,a solution based on Newton iteration was presented.Newton iterative function was established based on the parametric equations of pipe and annulus,by utilizing the geometric constraints between intersecting bodies and successive approximation with an appro-priate initial iteration value,the parametric equation was solved.The actual cutting angle of pipe-annulus intersecting on its mating surface was deduced;two types of pipe-annulus intersecting mating surface with a blunt edge,the riding type and the inserting type,were extended.Newton iteration is suitable for solving parametric equation of complex intersec-ting bodies′intersecting line for its advantage of simple programming and fast convergence.Contrasted the intersecting line between iterative algorithm and entity Boolean operations,the results demonstrated that the deviation of Newton it-erative is small,and its accuracy and reliability was considerable.

  9. Experimental Study on Inhibitory Effect of Niacinamide on Tumor Necrosis Factor-alpha-induced Matrix Degradation of Annulus Fibrous Tissue in vitro

    Institute of Scientific and Technical Information of China (English)

    Runbing XU; Zengwu SHAO; Liming XIONG

    2008-01-01

    Summary: The inhibitory effect of niacinamide on tumor necrosis factor-α (TNF-α) induced annulus fibrous (AF) degradation was assessed, and the mechanism of the inhibition was investigated. Chiba's intervertebral disc (IVD) culture model was established. Forty-eight IVDs from 12 adult Japanese white rabbits were randomly divided into 4 groups (12 IVDs in each group), and various concentrations of niacinamide and TNF-α were added to the medium for intervention: negative control group, niacinamide control group (0.5 mg/mL niacinamide), degeneration group (10 ng/mL TNF-α), and treatment group (0.5 mg/mL niacinamide and 10 ng/mL TNF-α). After one week's culture, AFs were collected for glycosaminoglycan (GS) content measurement, safranin O-fast green staining, and immunohistochemical staining for typeⅠ,Ⅱ collagen and cysteine containing aspartate specific protease-3 (Caspase-3). It was found that the GS content in treatment group was increased by about 48% as compared with degeneration group (t=16.93, P<0.001), and close to that in niacinamide control group (r=0.71, P=0.667). Safranine O-fast green staining exhibited higher staining density and better histological structure of AF in the treatment group as compared with the degeneration group. Immunohistochemical staining for both Type Ⅰ and Ⅱ collagen demonstrated that lameilar structure and continuity of collagen in treatment group were better reserved than in degeneration group. Positive staining rate of Caspase-3 in AFs of negative control group, niacinamide control group, degeneration group and treatment group was 3.4%, 4.3%, 17.9% and 10.3% respectively. The positive rate in treatment group was significantly lower than in degeneration group (P<0.01). It was concluded that niacinamide could effectively alleviate TNF-α induced destruction and synthesis inhibition of matrix ingredients in AFs. The inhibition may be related with reduction of expression of Caspase-3. Thus, niacinamide is of potential for

  10. Human disc cells in monolayer vs 3D culture: cell shape, division and matrix formation

    Directory of Open Access Journals (Sweden)

    Hanley Edward N

    2000-10-01

    Full Text Available Abstract Background The relationship between cell shape, proliferation, and extracellular matrix (ECM production, important aspects of cell behavior, is examined in a little-studied cell type, the human annulus cell from the intervertebral disc, during monolayer vs three-dimensional (3D culture. Results Three experimental studies showed that cells respond specifically to culture microenvironments by changes in cell shape, mitosis and ECM production: 1 Cell passages showed extensive immunohistochemical evidence of Type I and II collagens only in 3D culture. Chondroitin sulfate and keratan sulfate were abundant in both monolayer and 3D cultures. 2 Cells showed significantly greater proliferation in monolayer in the presence of platelet-derived growth factor compared to cells in 3D. 3 Cells on Matrigel™-coated monolayer substrates became rounded and formed nodular colonies, a finding absent during monolayer growth. Conclusions The cell's in vivo interactions with the ECM can regulate shape, gene expression and other cell functions. The shape of the annulus cell changes markedly during life: the young, healthy disc contains spindle shaped cells and abundant collagen. With aging and degeneration, many cells assume a strikingly different appearance, become rounded and are surrounded by unusual accumulations of ECM products. In vitro manipulation of disc cells provides an experimental window for testing how disc cells from given individuals respond when they are grown in environments which direct cells to have either spindle- or rounded-shapes. In vitro assessment of the response of such cells to platelet-derived growth factor and to Matrigel™ showed a continued influence of cell shape even in the presence of a growth factor stimulus. These findings contribute new information to the important issue of the influence of cell shape on cell behavior.

  11. 术中三维超声检测二尖瓣成形前后瓣环空间构型的变化%The annulus configuration changes after mitral repair measured by three dimensional echocardiography

    Institute of Scientific and Technical Information of China (English)

    张海波; 孟旭; 郭勇; 何怡华; 韩杰; 李岩

    2014-01-01

    echocardiography was performed before the operation in the operation room.The mitral annulus configuration,the mitral prolapse and regurgitation grades were examined.The mitral annulus diameter,the distance between commisure1 and commisure2,distance between anterior and posterior annulus,the annulus height and the non-planer angel were measured.The primary repair strategies were evaluated.The same procedure was done after the surgery.Results Totally 36 cases were enrolled,fully consistent with the intraoperative findings had 26 cases (72.2%),partially coincide had 6 cases (16.7%),the gap was larger in 4 cases (11.1%).The mitral annulus appears consistently as saddle shape during the whole movement phase,the lowest height was at the commissure part and the highest part was at the annulus.During the systolic phase the non-planer angel between anterior and posterior annuls appeared bigger than in diastolic phase.Disc ring circumference the disc ring diameter and disc ring longitudinal diameter before and after operation was (12.4 ± 2.4) cm,(7.5 ± 0.5) cm; (34.8 ± 2.7) mm,(21.8 ± 1.8) mm; (34.9 ± 3.1) mm,(20.4 ± 2.1) mm,respectively.The difference of disc ring circumference the disc ring diameter and disc ring longitudinal diameter before and after operation were statistically significant (P < 0.05).The annulus circumference,transverse,longitudinal diameters decreased compared with before the surgery.Preoperative mitral transverse diameter and longitudinal diameter values are almost the same,indicating that at this time the mitral annulus was in nearly round shape.However the longitudinal/transverse ratio reached 93% after surgery also implied that the mitral annulus configuration recovery after annuloplasty.After the surgery the annulus height decreased from (8.4 ± 0.6) mm to (3.0 ± 0.1) mm while the annular height/transverse diameter ratio decreased from 24% to 14%.Non-planar angle between the anterior and posterior mitral annuls increased from (135 ± 14

  12. 自体心包补片修补主动脉瓣环辅助主动脉瓣置换★%Autologous pericardium patch repairs the aortic annulus to assist aortic valve replacement

    Institute of Scientific and Technical Information of China (English)

    夏冰; 文冰; 许华山; 付国伟; 赵文增

    2013-01-01

      背景:在主动脉置换过程中常遇到瓣环钙化、瓣周囊肿等特殊情况,这时一般应用特殊技术辅助主动脉瓣置换。目的:观察自体心包补片修补主动脉瓣环辅助主动脉瓣置换治疗钙化性主动脉瓣狭窄并瓣环钙化的临床可行性。方法:回顾性分析2009年1月至2012年1月郑州大学第一附属医院42例钙化性主动脉瓣狭窄并瓣环钙化患者的临床资料,并通过统计学软件处理自体心包补片修补主动脉瓣环技术辅助主动脉瓣置换前后的主动脉瓣有效瓣口面积指数、最大跨瓣压差、血流峰值速度、左室射血分数等数据,分析自体心包补片修补主动脉瓣环技术辅助主动脉瓣置换的应用效果。结果与结论:无置换中死亡病例,置换中主动脉阻断时间为52-88(63.0±18.1) min,体外循环时间为78-122(102.6±25.1) min,置换后1例患者出现急性肾功能衰竭,经床旁血透治疗后治愈。余患者无严重置换并发症。置换后住院天数为7-20(13.6±5.5) d。置换后多普勒超声心动图示:瓣膜功能良好,均未发现主动脉瓣周漏。置换后6个月的主动脉瓣有效瓣口面积指数、最大跨瓣压差、血流峰值速度、左室射血分数均有显著改善,与置换前比较差异均有显著性意义(P <0.05)。证实对置换适应证合适的特殊换瓣患者,自体心包补片修补主动脉瓣环辅助主动脉瓣置换可取得满意的外科治疗效果,且操作安全简单,是一项可行的技术。%BACKGROUND: Annulus calcification and paravalvular cysts often appear during aortic valve replacement. At this time, special techniques are general y used to assist the aortic valve replacement. OBJECTIVE: To investigate the clinical feasibility of pericardium patch repaired aortic annulus to assist aortic valve replacement for the treatment of calcific aortic stenosis complicated by annulus calcification. METHODS: Forty two

  13. 环空流体吸入式自激振荡脉冲射流大涡模拟研究%Large eddy simulation of self-oscillation pulsed water jet drawing in annulus fluid

    Institute of Scientific and Technical Information of China (English)

    杜玉昆; 王瑞和; 倪红坚

    2009-01-01

    发展新型破岩钻井技术对于促进油气田高效开发具有重要意义,高压水射流是提高破岩钻井效率的一个重要手段,脉冲射流是一种高效射流形式.为了充分利用井底水力能量,提出了一种环空流体吸入式脉冲射流的技术构想.基于自激振荡原理设计了相应射流调制工具,并对工具的流场和动力学特性进行了大涡模拟研究.研究结果分析揭示了环空流体吸入式自激振荡脉冲射流调制的机理,并发现合理的水力结构可以在振荡腔内实现局部负压,使得环空流体被吸入,参与调制生成高效脉冲射流.与非吸入式脉冲射流相比,吸入式脉冲射流振荡更加剧烈,破岩能力更强.研究结果得到了实验验证,为实际钻井工具的研制和相关工艺技术的开发提供了依据.%It is of great significance that developing new rock breaking drilling technology to promote efficient exploit of oil field. High pressure water jet drilling technology is an important method to promote the rock breaking drilling efficiency, and pulsed water jet is such a kind of high efficiency water jet. In order to take full advantage of hydraulic energy in bottom hole, a concept of new type of pulsed water jet drawing in annulus flow, is put forward. The pulsed water jet modulation tool is designed based on the self-exciting principle, and the large eddy simulation is adopted to simulate the flow field and the dynamic characteristics in this tool. This simulation shows the modulation mechanism of self-exciting pulsed water jet drawing in annulus flow. Partial negative pressure could be achieved in the oscillating cavity if the reasonable hydraulic structure is applied. The negative pressure formed in the drawing entrance of the oscillating cavity provides assurance to automatically draw enough fluid into annulus flow, which takes part in modulating the efficient pulsed water jet. The amplitude is larger and the rock breaking capacity of

  14. 二尖瓣环摆动指数定量评估左心室舒张功能的临床研究%Quantitative evaluation of left ventricular diastolic function by swing index of mitral valve annulus

    Institute of Scientific and Technical Information of China (English)

    谢小岚; 董卫江; 张京成

    2014-01-01

    Objective To evaluate the left ventricular diastolic function (LVDF) by detecting the swing index of mitral valve annulus(SIMA). Methods Ninety six patients were divided into LVDF normal(n=30) and LVDF abnormal groups (n=66) based on the mean velocity of mitral annulus(e/a-mean). The displacements of mitral annulus moving to the apex at septum(TMAD1) and lat-eral (TMAD2) and midpoint (TMADmid) sites were measured by tissue motion annular displacement (TMAD) technique;the dis-placements of mitral annulus moving to the atrial roof at midpoint (TMADamid) was also recorded. The swing index of mitral annu-lar (SIMA) was calculated (SIMA=TMADamid/TMADmid ×100%). Results The SIMA was (6.02 ±1.39)% in normal group and (11.40±2.74)% in abnormal group (P<0.01). The SIMA was significantly correlated with e/a-mean ratio and E/emean ratio (r=- 0.82, r=0.89). Conclusion The SIMA was an effective index for evaluation of left ventricular diastolic function.%目的探讨组织运动瓣环位移追踪技术(TMAD)检测二尖瓣环摆动指数(SIMA),定量评估左心室舒张功能的价值。方法随机选取2011-01-2012-12住院的96例患者,根据二尖瓣环舒张期运动平均速度比值(e/a-mean)分为左室舒张功能异常组和正常组。应用TMAD获取相对于心尖的二尖瓣环室间隔(TMAD1)、侧壁(TMAD2)及此2位点连线中点(TMADmid)的位移值,以及相对于房间隔顶部的中点位移值(TMADamid),计算SIMA。结果两组患者的SIMA分别为(11.40±2.74)%、(6.02±1.39)%,比较有统计学差异(P<0.01)。SIMA与E/emean比值间呈正相关(r=0.89,P<0.01);而与e/a-mean比值呈负相关(r=-0.82,P<0.05)。结论SIMA能快速、客观地反映左心室舒张功能,是评估左心室舒张功能的有效指标。

  15. Boiling Heat Transfer Enhancement in a Vertical Annulus by Introduction of Air in Liquid Flow%内加热垂直环隙中引入惰性气体时的沸腾传热

    Institute of Scientific and Technical Information of China (English)

    王军; 苗君; 刘芸; 沈自求

    2004-01-01

    In this paper, boiling heat transfer in a vertical annulus with inner side heated with and without air introduction is experimentally studied. Results show that boiling heat transfer is significantly enhanced by the introduction of air. When air is introduced into the liquid with a temperature below boiling point, the enhancement of heat transfer is also detected. It is concluded from the study that the heat transfer enhanced by introduction of inert gas is due to the liquid vaporization at the gas-liquid interface near the wall, which removes a large amount of latent heat and lowers the interfacial temperature considerably. Thus the gas-liquid interface acts as a "heat sink"and the heat transfer is augmented significantly.

  16. Konno法和改良Manougnian法行主动脉瓣置换术的临床结果%Intermediate - term Clinical Outcomes of Konno and Modified Manougnian Methods on Adolescent Patients for Enlargement of Aortic Annulus

    Institute of Scientific and Technical Information of China (English)

    朱亚彬; 朱兵; 杨岷; 石维平; 王宁夫; K.M.Cherian; 刘志勇

    2012-01-01

    目的 观察Konno法和改良Manougnian法行主动脉瓣置换术的中期效果.方法 2001年7月~2009年11月对30例小主动脉瓣环青少年患者施行瓣环扩大的主动脉瓣置换术,其中Konno法12例(Konno组),改良Manougnian法18例(Manougnian组),比较术前和出院时、术后3年时超声心动图指标.结果 术后住院死亡1例,随访29例,随访率100%,术后左心室厚度、左心室重量指数均较术前明显改善,术后平均随访3年,心功能恢复程度无明显差别.但动态EOAI差异显著,Konno法较改良Manougnian法有较低的迟发性人工瓣膜不匹配现象发生;两组方法术后中期生存率无差异;术后3年左心室重量指数、左心室厚度、跨瓣压差有显著差异,Konno法较改良Manougnian心律失常发生率高.结论 两种扩大瓣环方式行主动脉瓣置换术在青少年患者中均能达到满意的短期效果和中期生存率,动态EOAI提示Konno法较改良Manougnian法更能减少人工瓣膜不匹配现象.%Objective To evaluate intermediate - term results of Konno and modified Manougnian methods on adolescent patients who underwent enlargement of aortic annulus for aortic valve replacement. Methods From July 2001 to Sep 2009, 30 patients underwent enlargement of aortic annulus to replace the large aortic valve prosthesis by using Konno operation and modified Manougnian operation. The dynamic change of EOAI and other relative indexes were reviewed by echocardiography( UCG) during follow - up. Results One patient had inpalient death in Manougnian group, and 29 cases received mean 3 years follow - up. No significant difference was found between two groups for heart function at discharge. There was significant difference in dynamic change of EOAI between two groups after 3years follow - up. Regression of left ventricular wall thickness, left ventricular mass index were improved after operation,but left ventricular wall thickness, left ventricular mass index

  17. 基于未知-信标迭代及圆环交汇的WSN定位算法%Localization Algorithm Based on Unknown-Beacon Iterative and Annulus Intersection in WSN

    Institute of Scientific and Technical Information of China (English)

    杨前程

    2016-01-01

    针对圆环交汇与网格扫描算法在定位时要求信标节点数量满足一定规模的缺陷,提出一种未知-信标迭代的基于圆环交汇与网格扫描改进算法。该算法通过将已定位的未知节点视为已知条件使用,引入信标节点迭代方法,解决了少量信标节点定位精度低的问题,增加了未知节点中已定位节点的循环利用。实验结果表明,改进算法提高了定位精度,并降低了对信标节点规模的依赖。%Aiming at the defect that the annulus intersection and grid scan algorithm required the number of beacon nodes to meet the size of a certain scale,the author proposed an improved algorithm based on annulus intersection and grid scan for unknown-beacon iterative.The algorithm took the localized unknown nodes as the known condition. The algorithm solved the problem of low localization precision of a small number of beacon nodes and increased the recycling utilization of the localized nodes in the unknown nodes by introducing the beacon node iterative method.Experimental results show that the improved algorithm can improve the localization precision and reduce the dependence on the scale of beacon nodes.

  18. Experimental study on natural convection of cold water near the maximum density in horizontal annulus%水平环缝内冷水自然对流换热实验

    Institute of Scientific and Technical Information of China (English)

    唐经文; 王林豪; 高诚; 梁鑫俐; 李佳

    2009-01-01

    对水平环缝内冷水自然对流换热性能进行了实验研究.水平环缝宽度为6~18 mm,外壁温度维持0℃,换热温差为2~24℃.结果表明,在实验范围内,内壁面的平均表面传热系数随环缝宽度的增大而增加;当温差小于4℃或大于8℃时,平均表面传热系数随温差的增大而增大,在4~8℃范围内,随温差的增大而减小.采用逐步线性回归方法,得到了内壁传热关联式.%This paper conducts the experimental study on the natural convection characteristics of cold water near the maximum density in horizontal annulus with the fixed inner radius r_i=14 mm and different width l = 6~18 mm. The temperature at outer wall is maintained at 0 ℃, and the temperature differences between the inner and outer walls range from 2 to 24 ℃. The results show that the heat transfer coefficient at inner wall increases with the increase of the annulus width. When the temperature difference is bellow 4 ℃ or above 8 ℃, the heat transfer coefficient increases with the increase of the temperature difference. When the temperature difference is between 4 ℃ and 8 ℃, it. decreases with the increase of the temperature difference. The formula of heat transfer at inner walls is obtained by using the method of linear regression.

  19. Transcatheter aortic valve implantation in patients with severe aortic valve stenosis and large aortic annulus, using the self-expanding 31-mm Medtronic CoreValve prosthesis: first clinical experience.

    Science.gov (United States)

    Nijhoff, Freek; Agostoni, Pierfrancesco; Amrane, Hafid; Latib, Azeem; Testa, Luca; Oreglia, Jacopo A; De Marco, Federico; Samim, Mariam; Bedogni, Francesco; Maisano, Francesco; Bruschi, Giuseppe; Colombo, Antonio; Van Boven, Ad J; Stella, Pieter R

    2014-08-01

    With the introduction of the 31-mm Medtronic CoreValve prosthesis, patients with large aortic annulus have become eligible for transcatheter aortic valve implantation. The aim of this study was to evaluate the feasibility, efficacy, and safety of transcatheter aortic valve implantation using the 31-mm Medtronic CoreValve in patients with severe aortic valve stenosis and large aortic annulus. Five institutions in the Netherlands and Italy participated in a retrospective multicenter registry. Clinical, procedural, and imaging data of patients treated with the 31-mm Medtronic CoreValve were retrospectively collected in accordance with the Valve Academic Research Consortium-2 criteria. Between August 2011 and November 2012, 47 patients (44 men, mean age 77.6 ± 8.9 years) received the 31-mm Medtronic CoreValve prosthesis for severe aortic stenosis. Device success (correct positioning of a single valve with intended performance and no all-cause 30-day mortality) was achieved in 31 patients (66.0%). Reasons for failing the device success criteria were significant prosthetic aortic regurgitation in 3 patients (6.4%), second valve implantation in 10 patients (21.2%) (8 cases of malpositioning with high-grade aortic regurgitation, 1 acute valve dislocation, and 1 delayed valve dislocation), 1 of whom died intrahospital, and in-hospital mortality in a further 3 patients (6.4%). Peak and mean transaortic gradients decreased significantly (P Medtronic CoreValve seemed to be challenging, even in experienced hands. If the prosthesis is properly implanted, it offers adequate valve hemodynamics and proper functioning. Copyright © 2014 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

  20. AN EXPERIMENTAL STUDY ON THE β EFFECT ACTING ONTHE THERMAL STRUCTURE OF BAROCLINIC WAVES IN A ROTATING ANNULUS%β平面上斜压波热力结构特性的实验研究

    Institute of Scientific and Technical Information of China (English)

    林上金; 仲孝恭; 成新喜; 魏岗; 周凯; 刘宇迪

    2001-01-01

    首次用转环实验模拟方法研究了β效应对斜压波热力结构的影响,发现β效应有抑制流动的水平混合和垂直混合的作用,使流动趋于正压;β平面上急流随高度降低而减弱,在急流的内外两侧各有一个无量纲温度值分布的突跃区,它们的空间结构与大气环流中的极锋锋区和北极锋锋区的结构相似.%The rotating annulus experiment is an important means in the study of rotating fluid dynamics. Geophysical fluid flows includes the atmosphere circulation. The generation, development and dynamics of the baroclinic can be simulated by rotating fluid annulus experiment.Therefor, the dynamic of the large scale quasi-geostrophic of atmosphere and ocean can be understand more deeply. The β effect is an important factor acting on the geophysical fluid flow. But there is no general accepted point of view in the important the β effect. There are two points of view to characters of atmospheric long wave, i.e., The one based on the classical theory, the other newer point of view believes that it is not the Rossby wave, but just a barolinic wave influenced by the β effect. An experiment study about the β effect action on the baroclinic wave in an rotating annulus is outlined in this paper. The quantization measures of temperature field of fluid flow in the rotating annulus has been accomplishes and the qualitative analysis about the inner thermal structure of the flow that acted by theβ effect is accomplished. The equipment of the experiment is a rotating annulus in which the inner wall and outer wall are kept at low and high temperature by a temperature control. The inner temperature of the flow is detected by the thermodetector with three dimensional fine grid. Comparing a group of the inner thermal structure of same surface flow pattern on the f plane and the β effect plane, the following results have been gotten in this paper. (1) On the f plane, the fluid flow are obviously. The

  1. Dupla ampliação anterior e posterior do anel aórtico para substituição valvar Anterior and posterior enlargement of the aortic annulus for valve replacement

    Directory of Open Access Journals (Sweden)

    João Ricardo SANT´ANNA

    2002-03-01

    Full Text Available OBJETIVO: Apresentar técnica de dupla ampliação anterior e posterior do anel aórtico, que difere das previamente descritas por utilizar enxertos distintos, para implante de prótese valvar e avaliar os resultados obtidos em 26 pacientes. MÉTODO: O procedimento é realizado com circulação extracorpórea convencional. Para substituição de valva nativa ou prótese aórtica estenótica, ampliação anelar posterior decorre da incisão no ponto médio do seio não coronário, que é estendida ao folheto mitral anterior; ampliação anterior resulta de incisão no anel aórtico anterior, estendida por 2 cm no septo interventricular, não transfixado. Reconstrução aórtica (e ampliação anelar é realizada mediante enxertos de pericárdio bovino distintos, sendo um triangular para incisão anterior e outro elíptico para incisão posterior. Após a fixação da prótese (mecânica ou biológica, a aorta ascendente é suturada com auxílio destes enxertos. Defeitos cardíacos associados são corrigidos. RESULTADOS: A operação aumentou o diâmetro do anel aórtico de 18,0 + 2,6 mmHg para 24,5 + 2,1 mmHg (pOBJECTIVES: To present a technique for anterior and posterior enlargement of the aortic anulus using individual patches and results in 26 patients. METHOD: Aortic valve surgery is performed with conventional cardiopulmonary bypass. For posterior enlargement, the longitudinal aortotomy is extended inferiorly and posteriosly in the mean portion of the noncoronary sinus, until the anterior mitral leaflet. Anterior enlargement results from incision between the two coronary ostium, extended in the left side of the ventricular septum for 2 cm. Two patches of bovine pericardium are sutured in the distal portion of the anterior and posterior incisions and the aortic prosthesis is fixed. Aorta is reconstructed with the patchs. Combined cardiac defects are corrected. RESULTS: Procedure resulted in increase of the annulus diameter from 18.0 + 2.6 mm

  2. Differential expression of galectin-1 and its interactions with cells and laminins in the intervertebral disc.

    Science.gov (United States)

    Jing, Liufang; So, Stephen; Lim, Shaun W; Richardson, William J; Fitch, Robert D; Setton, Lori A; Chen, Jun

    2012-12-01

    Galectin-1 (Gal-1), an endogenous β-galactoside-binding protein, binds to laminins, which are highly expressed in the nucleus pulposus (NP) of the intervertebral disc (IVD). The objective of this study is to evaluate the expression of Gal-1 protein in IVD tissues during aging and the effect of Gal-1 on IVD cell adhesion to laminins. Tissues from rat, porcine, and human (scoliosis or disc degeneration) IVDs were used to evaluate Gal-1 expression via immunostaining, RT-PCR, and Western blot analysis. Attachment of isolated IVD cells (porcine and human) on select laminin isoforms (LM-111 and LM-511) was compared with/without pre-incubation with exogenous Gal-1. A biotinylated Gal-1(B-Gal-1) was used to evaluate for binding to IVD cells and to select for IVD cells by magnetic activated cell sorting (MACS). NP cells expressed high levels of Gal-1 protein as compared to anulus fibrosus (AF) cells in immature tissues, while exogenous Gal-1 increased both NP and AF cell attachment to laminins and exhibited a similar binding to both cell types in vitro. With aging, Gal-1 levels in NP tissue appeared to decrease. In addition, incubation with B-Gal-1 was able to promote the retention of more than 50% of IVD cells via MACS. Our results provide new findings for the presence and functional role of Gal-1 within IVDs. Similar staining patterns for Gal-1 and LM-511 in IVD tissue suggest that Gal-1 may serve as an adhesion molecule to interact with both cells and laminins. This MACS protocol may be useful for selecting pure IVD cells from mixed cells of pathological tissue.

  3. Numerical analysis of laminar pulsating flow for power-law fluid in concentric annulus%幂律流体同心环空内层流脉动流的数值分析

    Institute of Scientific and Technical Information of China (English)

    黄善波; 李兆敏

    2011-01-01

    建立幂律流体环空内层流脉动流的数学模型,采用SIMPLE算法进行数值求解,得到幂律流体环空脉动层流的流动特性.结果表明:幂律流体环空脉动流的流动特性与稳态流动时差异较大;环空脉动流在距入口非常短的一段距离内就可达到充分发展,且不同时刻的人口段长度随时间而变化;低脉动频率下速度分布曲线类似于稳态时的抛物形分布,高频率下壁面附近的速度分布曲线发生扭曲,振荡速度的最大值出现在壁面附近;内、外壁面的摩擦系数和轴向压力梯度均近似满足正弦变化规律,脉动频率、振幅和流体流性指数的增加均会使壁面摩擦系数和轴向压力梯度及其变化幅度增大.%A mathematical model for laminar pulsating flow of power-law fluid in annulus was set up and solved by SIMPLE method. The results show that the flow behavior of pulsating flow is quite different from that of steady flow. Fully developed lamilar flow can be achieved in a small distance from the annulus entrance. and the hydrodynamic entrance length varies with time. The transient pulsating velocity curve at low pulsating frequency is similar to parabolic distribution of steady flow. The influence of pulsation is distinct at high frequency and the maxmum oscillating velocity component appears near the wall.The wall friction coefficient and the axial pressure gradient vary with time approximately in sinusoidal manner. The friction coefficient at inner and outer wall and the axial pressure gradient and their variation range all increase with the increase of pulsating frequency, amplitude and the flow index of fluid.

  4. Predictors of paravalvular aortic regurgitation following self-expanding Medtronic CoreValve implantation: the role of annulus size, degree of calcification, and balloon size during pre-implantation valvuloplasty and implant depth.

    Science.gov (United States)

    Ali, O F; Schultz, C; Jabbour, A; Rubens, M; Mittal, T; Mohiaddin, R; Davies, S; Di Mario, C; Van der Boon, R; Ahmad, A S; Amrani, M; Moat, N; De Jaegere, P P T; Dalby, M

    2015-01-20

    We sought to investigate the role of balloon size during pre-implantation valvuloplasty in predicting AR and optimal Medtronic CoreValve (MCS) implantation depth. Paravalvular aortic regurgitation (AR) is common following MCS implantation. A number of anatomical and procedural variables have been proposed as determinants of AR including degree of valve calcification, valve undersizing and implantation depth. We conducted a multicenter retrospective analysis of 282 patients who had undergone MCS implantation with prior cardiac CT annular sizing between 2007 and 2011. Native valve minimum (Dmin), maximum (Dmax) and arithmetic mean (Dmean) annulus diameters as well as agatston calcium score were recorded. Nominal and achieved balloon size was also recorded. AR was assessed using contrast angiography at the end of each procedure. Implant depth was measured as the mean distance from the nadir of the non- and left coronary sinuses to the distal valve frame angiographically. 29 mm and 26 mm MCS were implanted in 60% and 39% of patients respectively. The majority of patients (N=165) developed AR <2 following MCS implantation. AR ≥3 was observed in 16% of the study population. High agatston calcium score and Dmean were found to be independent predictors of AR ≥3 in multivariate analysis (P<0.0001). Nominal balloon diameter and the number of balloon inflations did not influence AR. However a small achieved balloon diameter-to-Dmean ratio (≤0.85) showed modest correlation with AR ≥3 (P=0.04). This observation was made irrespective of the degree of valve calcification. A small MCS size-to-Dmean ratio is also associated with AR ≥3 (P=0.001). A mean implantation depth of ≥8+2mm was also associated with AR ≥3. Implantation depth of ≥12 mm was associated with small MCS diameter-to-Dmean ratio and increased 30-day mortality. CT measured aortic annulus diameter and agatston calcium score remain important predictors of significant AR. Other procedural predictors

  5. Calculation of Annulus Pressure on Managed Pressure Drilling in Daqing Oil Field%大庆油田控压钻井作业环空压力的计算

    Institute of Scientific and Technical Information of China (English)

    李士斌; 周艳; 邸百英; 宋瑞宏

    2011-01-01

    根据Beggs-Brill的流动型态模型推导出了控制压力钻井环空多相流的压力计算公式;并提出了井口回压对环空流态的影响.提出的计算模型已通过现场试验的验证.试验结果表明其误差只有3%左右,能够指导现场作业.为控制压力钻井技术在大庆油田的应用和发展提供理论依据.%According to the mobile state model of Beggs-Brill to infer the multiphase calculation formula of manage pressure drilling, the well head back pressure influence the annulus state is proposed. The computation model is proposed through the field test confirmation. The test result has indicated its error only then about 3%, could instruct the field operation. The theory basis for MPD in the Daqing Oil Field application and the development is provided.

  6. Clinical research of aortic valve replacement in small aortic annulus%小主动脉瓣环行主动脉瓣置换术的临床研究

    Institute of Scientific and Technical Information of China (English)

    王睿; 陈鑫; 徐明; 蒋英硕; 汪黎明; 刘培生

    2014-01-01

    Objective To compare the effect aortic valve replacement(AVR) combined with aortic root enlargement and simple St.Jude Regent AVR in small aortic annulus patients.Methods From June 2008 to June 2012,62 severe aortic valvular stenosis patients with small aortic annulus (annulus diameter of 15-21 mm) entered the study.Twenty-seven cases received AVR combined with aortic root enlargement (enlargement group) and 35 cases received simple St.Jude Regent AVR(non-enlargement group),17 mm St.Jude Regent in 15 cases(17 mm group) and 19 mm in 20 cases(19 mm group).Aortic root enlargement techniques included Nicks in 2,modified Nicks in 6 cases,modified Manouguian in 19 cases.Patients were followed up and received ultrasonic cardiogram (UCG) 3,12 months postoperatively and t-test was used for statistical comparison.Results In enlargement group,1 Nicks patient received reoperation due to aortic root hemorrhage,and died of mediastinal infection,1 Manouguian patient received permanent pacemaker.In non-enlargement group,low cardiac output syndrome in 1 case.Three months and 12 months postoperative UCG showed,comparing to preoperation,effective orifice area (EOAI) increased significantly,postoperative transvalular pressure gradient and flow rate decreased significantly in each group (P =0.000).Left ventricular diastolic diameter (LVDd) decreased significantly in both enlargement group and 19 mm group (P =0.000),but no significant change in 17 mm group (P > 0.05).In non-enlargement group,19 mm compared to 17 mm group,3 months and 12 months postoperative EOAI increased significantly,pressure gradient,flow rate and LVDd decreased significantly (t =2.449-12.291,P =0.000-0.029).Comparing to enlargement group,there were significant differences in EOAI,pressure gradient,flow rate and LVDd in 17 mm group(t =2.278-17.860,P =0.000-0.028),but no significant differences in 19 mm group(t =0.118-1.630,P =0.110-0.907).Conclusions For small aortic annulus AVR patient,19 mm and larger St

  7. 成骨蛋白-1对髓核抽吸术后兔腰椎间盘组织病理变化的影响%The influence of osteogenic protein-1 on histologic changes of rabbit lumbar disc induced by aspiring the nucleus pulposus

    Institute of Scientific and Technical Information of China (English)

    刘航涛; 林国叶; 李平生; 林智军; 黄云梅; 陈国仙; 王万明

    2013-01-01

    Objectives: To observe the influence of osteogenic protein-1 (OP-1) on disc histologic changes induced by aspirating the nucleus pulposus. Methods: All the 32 Japanese rabbits' posterior annulus fibrosus of L1/2 and L3/4 disc were stabbed by 21-gauge hypodermic needle, then some nucleus pulposus tissues were aspirated out. 25μl OP-1 was injected into L3/4 disc by using micro-injection syringe as the experimental group (OP-1 group). 25μl normal saline was taken injected into L1/2 as a blank control disc(Saline group). L2/3 was taken as a normal control disc(normal group). At 2, 4, 8 and 12 weeks after operation, each 8 rabbits were executed and the disc tissues of L1/2, L2/3, L3/4 were harvested and sliced rapidly, stained by Masson for observation. Results: In the normal intervertebral disc, nucleus pulposus tissue collagen was sparse and lined orderly. The cells were distributed as island. Anulus fibrosus collagen fibers were lined regularly, without distortion and delamination. The intervertebral disc showed no significant pathological change at 2, 4, 8 and 12 weeks after operation. In saline group at 2 weeks after operation, excalation of the nucleus pulposus, collagen disarrangement and a large inhomogeneous amorphous particles could be observed. At 4 weeks after operation, the nucleus pulposus tissue formed cracks. More cartilage cells appeared. Collagen fibers were seriously distorted. At 8 weeks after operation, nucleus pulposus tissue had wide fissure. Collagen was arranged extremely disorder. A few cells appeared just between cartilage -like cells and fibroblasts. Layered fissure was formed. Collagen fibers were extremely distorted, with part of fracture evidenced. Gelatinous nucleus pulposus of disc showed significant fibrosis at 12 weeks after operation. Fibroblasts increased in nucleus pulposus region, and the number of cartilage-like cells decreased. The annulus fibrosus appeared huge layered fissure, with part of fracture evidenced. In OP-1 group at

  8. Expression of matrix factors in the process of neovascularization of intervertebral disc

    Directory of Open Access Journals (Sweden)

    Pedro Henrique Isoldi Pohl

    2015-06-01

    Full Text Available OBJECTIVE: To investigate the effects of proteins products of endothelial cells (ECs on the annulus fibrosus (AF cell metabolism in an in vitro culture.METHODS:Human AF cells were expanded in monolayer cultures and treated with proteins from the medium of cell line HMEC-1 (Human Microvascular Endothelial Cells (125µg/ml. After 72h of treatment RNA was isolated from AF cells for analysis of gene expression and the culture medium was collected for protein expression analysis.RESULTS: The qRT-PCR analysis demonstrated increased gene expression of matrix metalloproteinases (MMPs in AF cells treated with protein products of endothelial cells compared with cells from control group of AF cells: MMP-1 243.10 times (pCONCLUSIONS: In this study, we observed that the proteins produced by ECs induced the MMPs expression and suppressed the TIMPs as well as the aggrecan in primary cells of the human intervertebral disc, targeting the development of potential treatments for intervertebral disc degeneration and associated discogenic pain.

  9. Evaluation of lumbar disc lesions in teen-agers using magnetic resonance imaging; A correlative study between peridiscal signal intensity and nuclear signal intensity in 500 discs

    Energy Technology Data Exchange (ETDEWEB)

    Urakado, Misao; Naruo, Masakuni; Koyanagi, Eiichi; Taoka, Yuuji; Shiiba, Mutuo; Ryouki, Yoshihiro; Kitazono, Tooru; Kato, Yoshiyuki (Naruo Orthopedic Hospital, Kumamoto (Japan))

    1993-09-01

    The peridiscal and nuclear (nucleus pulposus and inner layer of annulus fibrosus) signal intensities in 500 discs of teen-age patients were compared with common degenerative lumbar disc disease. Images were taken with a 7 mm slice thickness and T[sub 2] weighted (TE 80[approx]90 mS, TR 2000[approx]2200 mS) midsagittal imaging. Clear correlation between these intensities was found. The signal intensity primarily decreased in the peridiscal tissues and secondarily decreased in the nucleus pulposus and inner layer of annulus fibrosus. These findings suggest that peridiscal disorders cause degenerative changes of the nucleus pulposus. Additionally, in the early degenerative stage of the teen-age lumbar disc, a decrease of nuclear signal intensity indicated that degenerative changes originated from the anterior portion and extended posteriorly. (author).

  10. Development and Implementation of a Transversely Isotropic Hyperelastic Constitutive Model With Two Fiber Families to Represent Anisotropic Soft Biological Tissues

    Science.gov (United States)

    2014-06-01

    region ( cervical , thoracic or lumbar), and, starting with the most superior (highest) vertebra in that region, numbered consecutively until the most...plane of the intervertebral disc have all been used by researchers to model the fibers of the annulus fibrosus (1, 18–20). CERVICAL VERTEBRAE THORACIC...typical vertebra (panel b). Vertebra are color-coded according to their location classification. Panel c is an illustration (not drawn to scale) of an

  11. 井下油套环空级联式光纤光栅压力传感器的研制%Fabrication of cascaded fiber grating pressure sensor for annulus of rod pumping wells

    Institute of Scientific and Technical Information of China (English)

    潘洪亮; 董惠娟; 何俊; 张广玉

    2012-01-01

    In order to realizethe pressure measurement with wide range in narrow sapce of annulus of rod pumping wells,a cascaded fiber grating pressure sensor has been developed.First,according to the actual working condition,a packaging structure of optical fiber grating pressure sensor is designed based on the combination of flat diaphragm and equal-strength beam.Using the method of cascading,the measuring range is expanded without changing the performance index of optical fiber grating,and the contradiction between pressure measurement range and sensitivity is solved.Then the rationality and feasibility of this structure are verified through mechanical analysis,and the temperature compensation method of cascaded pressure sensor is expounded.Finally,the experimental results show that the pressure measuring range is from 0 to 30 MPa,sensitivity is 329 pm/MPa,and linear degree is above 98%.The sensor is simple and small in structure,easy to realize,and the actual thickness is only 17 mm after assembling to the tube,which can satisfy requirements of pressure monitoring in annulus of rod pumping wells.%为了实现对油水井下油套环空中狭小空间大量程压力的监测,研制一种级联式的光纤光栅压力传感器。首先,根据实际工况,设计一种基于平膜片和等强度梁相结合的光纤光栅压力传感器封装结构;采用级联式的方法,在未改变原有光纤光栅性能指标的前提下,扩大传感器的测量范围,解决压力测量范围和灵敏度之间的矛盾;通过力学分析验证研制的传感器结构的合理性与可行性,同时阐明其温度补偿的方法。实验结果表明:本文传感器的测压范围为0~30MPa,灵敏度为329.5pm/MPa,线性度达到98%以上。并且传感器结构简单,尺寸小巧,易于实现,装配到油管后的实际厚度仅为17mm,能够满足油水井下油套环空中压力的监测要求。

  12. INNERVATION OF SENSORY NERVE TERMINALS IN RAT LUMBAR INTERVERTEBRAL DISC AND POSTERIOR LONGITUDINAL LIGAMENT

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Objective:To investigate the distribution of sensory nerve terminals in the lumbar intervertebral disc and posterior longitudinal ligament(PLL)in an animal model.Methods:Immunohistochemical method was used to visualize nerve terminals with antibodies of substanceP(SP) and calcitonin gene-related peptide(CGRP),and to characterize sensory nerve terminals on sections from lumbar intervertebral disc and posterior longitudinal ligament(PLL) of the sprague Dawley rate.Results :The immunostaining revealed an extensive distribution of SP and CGRP immunoreactive nerve filbers in the surface and most superficial portions of all annulus fibrosus and PLL.Most immunoreactions were observed in ventral and lateral regions of the annulus fibrosus,Morphologically,both thin varicose nerve fibers and tiny punctate nerve terminals could be observed.Conclusion:This study demonstrates an extensive distribution of SP and CGRP immunoreactive nerve fibers throughout the PLL and the peripheral annulus fibrosus and provides an illustration of this distribution.This finding supports a role for the disc as a source of low back pain and provides the neuroanatomic foundation of the disc-genic pain.

  13. INNERVATION OF SENSORY NERVE TERMINALS IN RAT LUMBAR INTERVERTEBRAL DISC AND POSTERIOR LONGITUDINAL LIGAMENT

    Institute of Scientific and Technical Information of China (English)

    韩学哲; 王民; 刘淼; 赵昌松

    2002-01-01

    Objective To investigate the distribution of sen sory nerve terminals in the lumbar intervertebral disc and posterior longitudina l ligament (PLL) in an animal model. Methods Immunohistochemical method was used to visualize nerve terminals with antibodies of substance P(SP) and calcitonin gene-related pepti de(CGRP), and to characterize sensory nerve terminals on sections from lumbar in tervertebral disc and posterior longitudinal ligament(PLL) of the Sprague Dawley rats.Results The immunostaining revealed an extensive distribution o f SP and CGRP immunoreactive nerve fibers in the surface and most superficial po rtions of all annulus fibrosus and PLL. Most immunoreactions were observed in ve ntral and lateral regions of the annulus fibrosus. Morphologically, both thin va ricose nerve fibers and tiny punctate nerve terminals could be observed. Conclusion This study demonstrates an extensive distribution o f SP and CGRP immunoreactive nerve fibers throughout the PLL and the peripheral annulus fibrosus and provides an illustration of this distribution. This finding supports a role for the disc as a source of low back pain and provides the neur oanatomic foundation of the disc-genic pain.

  14. Altered lumbar spine structure, biochemistry and biomechanical properties in a canine model of mucopolysaccharidosis type VII

    Science.gov (United States)

    Smith, Lachlan J; Martin, John T; Szczesny, Spencer E; Ponder, Katherine P; Haskins, Mark E; Elliott, Dawn M

    2010-01-01

    Mucopolysaccharidosis VII (MPS VII) is a lysosomal storage disorder characterized by a deficiency in β-glucuronidase activity, leading to systemic accumulation of poorly degraded glycosaminoglycans (GAG). Along with other morbidities, MPS VII is associated with paediatric spinal deformity. The objective of this study was to examine potential associations between abnormal lumbar spine matrix structure and composition in MPS VII, and spine segment and tissue-level mechanical properties, using a naturally occurring canine model with a similar clinical phenotype to the human form of the disorder. Segments from juvenile MPS VII and unaffected dogs were allocated to: radiography, gross morphology, histology, biochemistry, and mechanical testing. MPS VII spines had radiolucent lesions in the vertebral body epiphyses. Histologically, this corresponded to a GAG-rich cartilaginous region in place of bone, and elevated GAG staining was seen in the annulus fibrosus. Biochemically, MPS VII samples had elevated GAG in the outer annulus fibrosus and epiphyses, low calcium in the epiphyses, and high water content in all regions except the nucleus pulposus. MPS VII spine segments had higher range of motion and lower stiffness than controls. Endplate indentation stiffness and failure loads were significantly lower in MPS VII samples, while annulus fibrosus tensile mechanical properties were normal. Vertebral body lesions in MPS VII spines suggest a failure to convert cartilage to bone during development. Low stiffness in these regions likely contributes to mechanical weakness in motion segments and is a potential factor in the progression of spinal deformity. PMID:19918911

  15. 二尖瓣成形术中使用二维平面人工环影响瓣环生理性空间构型%The three dimensional annulus configuration changes after application of two dimensional artificial mitral annuloplasty

    Institute of Scientific and Technical Information of China (English)

    张海波; 孟旭; 郭勇; 何怡华; 韩杰; 李岩

    2015-01-01

    Objective To investigate the mitral annular three dimensional configuration changes after application of two dimensional mitral annuloplasty.Methods Includes criteria:serious mitral prolapse without other cardiac disorders,with age ranged from 18 to 60 years old.Three dimensional echocardiography was performed before the surgery in the operation room.The mitral annular three dimensional configuration,the mitral prolapse and regurgitation grades were examined.And same procedure was done after the mitral repair.All the measure results were expressed as x ± s and the statistical analysis was performed using SPSS 19.0 software.Results Totally 42 cases were enrolled,including 28 posterior prolapse and 14 anterior prolapse cases.All the mitral repair got satisfied none or mild regurgitation.The mitral annulus moved consistently as saddle shape during the whole cardiac cycle,the lowest annulus part was at the commissure and the highest part was at the anterior and posterior annulus centers.During the systolic phase the non-planer angel between anterior and posterior annuls was bigger than in diastolic phase.The annulus circumference,transverse,longitudinal diameters decreased compared with before the surgery.Preoperative mitral transverse diameter and longitudinal diameter values are almost the equal size,indicating the mitral annulus was in nearly round shape.However the longitudinal/transverse ratio reached 0.88 after surgery which implied the annulus configuration recovery after annuloplasty.After the mitral annuloplasty the annular height decreased from (8.4 ± 0.6) mm to (3.2 ±0.1) mm while the annular height/transverse diameter ratio decreased from 0.24 to 0.15,which may be affected by the application of the two dimensional rigid artificial annulus.Non-planar angle between the anterior and posterior mitral annuls increased from(136 ± 13)degrees to(145 ± 14) degrees after mitral repair.Conclusion The mitral annulus configuration may have planarization changes due

  16. Cells

    Directory of Open Access Journals (Sweden)

    Zhao-Hui Jin

    2012-11-01

    Full Text Available As cancer stem cells (CSCs are postulated to play critical roles in cancer development, including metastasis and recurrence, CSC imaging would provide valuable information for cancer treatment and lead to CSC-targeted therapy. To assess the possibility of in vivo CSC targeting, we conducted basic studies on radioimmunotargeting of cancer cells positive for CD133, a CSC marker recognized in various cancers. Antibodies against CD133 were labeled with 125I, and their in vitro cell binding properties were tested. Using the same isotype IgG as a control, in vivo biodistribution of the labeled antibody retaining immunoreactivity was examined in mice bearing an HCT116 xenograft in which a population of the cancer cells expressed CD133. Intratumoral distribution of the labeled antibody was examined and compared to the CD133 expression pattern. The 125I-labeled anti-CD133 antibody showed a modest but significantly higher accumulation in the HCT116 xenograft compared to the control IgG. The intratumoral distribution of the labeled antibody mostly overlapped with the CD133 expression, whereas the control IgG was found in the area close to the necrotic tumor center. Our results indicate that noninvasive in vivo targeting of CSCs could be possible with radiolabeled antibodies against cell membrane markers.

  17. 小主动脉瓣环188例患者人工机械瓣换瓣术后疗效观察%Clinical effect evaluation of 188 patients after aortic mechanical valve replacement with small aortic annulus

    Institute of Scientific and Technical Information of China (English)

    叶生爱; 于裕; 郁大江; 赵扬; 程亮; 张颖; 张辉; 陈振强

    2016-01-01

    均左心室质量指数为90.35 g/m2,较术前(101.48 g/m2)下降显著(P and measured, and comparative analyzed in groups. Results Two patients were dead perioperative and 3 patients were dead within postopertive 1-year in unexplained causes, and other 183 patients were followed up above 1-year. The effective ori-fice area index(EOAI) was provided by manufacturer. There was no severe PPM and the EOAI of all patients were more than 0.65 cm2/m2, moderate PPM patients(EOAI of 0.65 - 0.85 cm2/m2) was 35.14 % and EOAI more 0.85 cm2/m2 was 64.86 %, there was no significant correlation between EOAI and aortic trans-valvular pressure gradient;All patients cardiac function were improved 2-3 grades after operation, the LVEF, LVFS and mean left ventricular diameter were in normal levels after operation 3-month to 1-year. The mean left ventricular mass index after operation 1-week was 90.35 g/m2, which decreased than preopera-tive(108.48 g/m2) and was no significant changes in followed-up from 3-month to 1-year. The mean aortic valve transvalvular pressure gradients of all patients were 2.92 kPa(21.92 mmHg) after operation from 1-week to 1-year, which were no significantly changed;The aortic valve transvalvular pressure gradients were significantly larger in 5 groups(16 mm over-line Sorin mechanical valve group, 20 mm over-line Sorin mechanical valve group, SJ Regent 17 mm mechanical valve group, Carbio-S 19 mm mechan-ical valve group and Carbio-S 21 mm mechanical valve group), compared with other 3 groups, the differences were statistically significant(P<0.05), and the aortic valve transvalvular pressure gradient of 16 mm over-line Sorin group was the biggest. All pa-tients were no occurred PPM phenomenon. Conclusion It is demonstrated that no severe PPM phenomenon in small aortic an-nulus patients with aortic valve replacement, the left ventricular mass index and aortic across valve pressure gradient are in ideal range. The different diameter artificial aortic

  18. Development of a metal annulus-based low frequency fiber Bragg grating vibration sensing system%金属环封装低频光纤布拉格光栅振动传感系统研制

    Institute of Scientific and Technical Information of China (English)

    王建飞; 于洋; 罗洪; 孟洲

    2012-01-01

    A metal annulus-based single cylinder mandrel structure fiber Bragg grating(FBG) vibration sensor and a phase generated carrier(PGC) demodulator based on an unbalanced Michelson interferometer are proposed in this paper.The high precision and real time signal detection are achieved for this FBG vibration sensor.Experimental results show that its resonance frequency is 388 Hz and its acceleration sensitivity is around 81 pm/g over the frequency range from 10 Hz to 200 Hz,with fluctuation at different frequencies less than 1 dB.This FBG vibration sensor is suitable for monitoring vibration signals below the frequency of 200Hz.The wavelength resolution of the demodulation system is 1.07×10-3 pm,and the acceleration resolution of the sensing system is 1.3×10-5 g.%研制了一种金属环封装的单柱体芯轴式光纤布拉格光栅(FBG)振动传感器,搭建了基于非平衡迈克耳逊干涉仪相位载波调制(PGC)解调技术的FBG振动传感器解调系统,实现了低频振动信号的高精度实时解调,并分析了各参数对传感器谐振频率和灵敏度等特性的影响。实验结果表明,研制的FBG振动传感器谐振频率为388Hz,在10~200Hz频率范围内,传感器的加速度灵敏度约为81pm/g,且加速度响应平坦,起伏小于1dB,与理论分析结果基本一致。研制的振动传感器可实现200Hz以下低频振动信号的实时检测,解调系统的波长检测精度为1.07×10-3 pm,最小可检测加速度为1.3×10-5 g。

  19. 大涡模拟研究液态金属在环形管道内的湍流换热%Large eddy simulation for the turbulent heat transfer of liquid metal in an annulus

    Institute of Scientific and Technical Information of China (English)

    吕逸君; 彭勇升; 葛志浩; 赵平辉

    2015-01-01

    使用大涡模拟方法,在雷诺数为 Re =8900和分子普朗特数 Pr =0.01,0.026,0.2,0.4,0.71条件下对环形管道内的湍流对流换热过程进行数值模拟,计算分析湍流传热场中的平均温度、温度脉动、湍流热通量及湍流普朗特数 Pr t 等物理量.通过与传统流体(Pr =0.4,0.71)的计算结果进行比较,研究了液态金属流体(Pr =0.01,0.026)的湍流对流换热特性.结果表明,液态金属流体湍流换热过程中分子热传导占主导地位,其湍流温度边界层内的线性区变长、对数律区变短甚至消失,温度脉动、湍流热通量变小.此外,相对于传统流体,液态金属的湍流普朗特数 Pr t 比较大,且对Pr 的变化很敏感.%Large eddy simulations (LES)for turbulent heat transfer at different molecular Prandtl numbers (Pr = 0.01,0.026,0.2,0.4,0.71 )at Re = 8 900 in an annulus were performed.Several statistics quantities such as time-mean temperature,temperature fluctuation,turbulent heat flux and turbulent Prandtl number were presented and analyzed.The characteristics of turbulent heat transfer of liquid metal (Pr=0.01,0.026)were compared with those of the traditional fluids (Pr=0.4,0.71).The results show that the molecular conduction is the dominant heat transfer mechanism for the liquid metal.The linear law region extends larger while the logarithmic law region becomes shorter and even disappears compared to traditional fluids.With the decrease of Pr,the temperature fluctuation and turbulent heat flux become smaller.Beside,the turbulent Prandtl number of liquid metal is bigger than that of traditional fluids and is very sensitive to its molecular Prandtl number Pr.

  20. Terrestrial Planet Formation from an Annulus

    CERN Document Server

    Walsh, Kevin J

    2016-01-01

    It has been shown that some aspects of the terrestrial planets can be explained, particularly the Earth/Mars mass ratio, when they form from a truncated disk with an outer edge near 1.0 au (Hansen 2009). This has been previously modeled starting from an intermediate stage of growth utilizing pre-formed planetary embryos. We present simulations that were designed to test this idea by following the growth process from km-sized objects located between 0.7 to 1.0 au up to terrestrial planets. The simulations explore initial conditions where the solids in the disk are planetesimals with radii initially between 3 and 300 km, alternately including effects from a dissipating gaseous solar nebula and collisional fragmentation. We use a new Lagrangian code known as LIPAD (Levison et al. 2012), which is a particle-based code that models the fragmentation, accretion and dynamical evolution of a large number of planetesimals, and can model the entire growth process from km-sizes up to planets. A suite of large (Mars mass)...

  1. Coaxial Propellant Injectors With Faceplate Annulus Control

    Science.gov (United States)

    Horn, Mark D.; Miyata, Shinjiro; Farhangi, Shahram

    2010-01-01

    An improved design concept for coaxial propellant injectors for a rocket engine (or perhaps for a non-rocket combustion chamber) offers advantages of greater robustness, less complexity, fewer parts, lower cost, and less bulk, relative to prior injectors of equivalent functionality. This design concept is particularly well suited to small, tight-tolerance injectors, for which prior designs are not suitable because the practical implementation of those designs entails very high costs and difficulty in adhering to the tolerances.

  2. Effects of Nd:YAG laser radiation in cultured porcine vertebral disc tissue

    Science.gov (United States)

    Thal, Dietmar R.; Werkmann, Klaus; Leheta, Fouad; Schober, Ralf; Ulrich, Peter

    1996-01-01

    Nd:Yag laser radiation is used for the treatment of protrusion of intervertebral discs. It is known that laser radiation leads to coagulation, vaporization and carbonization of the disk. Little is known about the early changes in vertebral discs after laser radiation. Therefore, we exposed cadaveric porcine vertebral discs by Nd:YAG laser radiation immediately after death. The discs were quartered and either formalin fixed after laser radiation or kept in culture for 1, 4 and 7 days and then formalin fixed. Immunohistochemistry was performed with antibodies directed against vimentin and amyloid precursor protein (APP). Results showed a jerky leak of notochordial remnant cells and mucopolysaccharides at the distal end of the application needle during laser radiation, which was interpreted as a bursting extrusion of damaged but not vaporized tissue. Histology and immunohistochemistry revealed an incomplete loss of nucleus pulposus and a large, almost complete necrosis of the notochordial remnant cells. In surviving notochordial remnant cells after laser radiation a slight increase of vimentin and APP could be seen without any other cellular reactions. The annulus fibrosus showed no significant changes except a defect with a small necrosis zone at the site of the application needle. Therefore, it can be concluded that Nd:YAG laser radiation leads to an increased volume reduction by the leak of nucleus pulposus and to a slight cellular reaction of surviving notochordal remnant cells detectable by vimentin and APP increase.

  3. Translation of an engineered nanofibrous disc-like angle-ply structure for intervertebral disc replacement in a small animal model.

    Science.gov (United States)

    Martin, John T; Milby, Andrew H; Chiaro, Joseph A; Kim, Dong Hwa; Hebela, Nader M; Smith, Lachlan J; Elliott, Dawn M; Mauck, Robert L

    2014-06-01

    Intervertebral disc degeneration has been implicated in the etiology of low back pain; however, the current surgical strategies for treating symptomatic disc disease are limited. A variety of materials have been developed to replace disc components, including the nucleus pulposus (NP), the annulus fibrosus (AF) and their combination into disc-like engineered constructs. We have previously shown that layers of electrospun poly(ε-caprolactone) scaffold, mimicking the hierarchical organization of the native AF, can achieve functional parity with native tissue. Likewise, we have combined these structures with cell-seeded hydrogels (as an NP replacement) to form disc-like angle-ply structures (DAPS). The objective of this study was to develop a model for the evaluation of DAPS in vivo. Through a series of studies, we developed a surgical approach to replace the rat caudal disc with an acellular DAPS and then stabilized the motion segment via external fixation. We then optimized cell infiltration into DAPS by including sacrificial poly(ethylene oxide) layers interspersed throughout the angle-ply structure. Our findings illustrate that DAPS are stable in the caudal spine, are infiltrated by cells from the peri-implant space and that infiltration is expedited by providing additional routes for cell migration. These findings establish a new in vivo platform in which to evaluate and optimize the design of functional disc replacements.

  4. The electrocardiogram characteristics and clinical results of radiofrequency ablation on idiopathic ventricular arrhythmias originating from the tricuspid annulus%特发性三尖瓣环室性心律失常的心电图特征和导管消融疗效分析

    Institute of Scientific and Technical Information of China (English)

    舒茂琴; 钟理; 冉擘力; 宋治远; 周扬; 刘燕; 朱平; 李华康; 刘建平

    2013-01-01

    Objective To clarify the characteristics of electrocardiography(ECG) and the clinical value on idiopathic ventricular arrhythmias (ⅣAs) originating from the tricuspid annulus.Methods The characteristics of ECG and clinical results of the CARTO mapping system in the guiding of catheter ablation were analyzed in 246 patients with ⅣAs from January 2011 to December 2012 in our center.Results Twenty-two (8.9%) patients (14 males and 12 females) at the age of 34.5 ±6.8 years had ⅣAs (including 3 patients with ventricular tachycardia and 19 cases of ventricular premature beats) arising from the tricuspid annulus:15 patients (68.2%) originated from the free wall of the tricuspid annulus and the remaining 11 (31.8%) from the septal portion of the tricuspid annulus.A total of 22 had a characteristic ECG with a left bundle branch block and R of±wave in lead aVL." Notching" of the QRS complex and R-wave transition beyond lead V3 was observed more often in ⅣAs arising from the free wall of the tricuspid annulus than those from the septum of the tricuspid annulus (P < 0.05).20 cases of ⅣAs arising from tricuspid annulus were successfully ablated (90.9%),and 1 case complicated by right bundle branch block at discharge.Conclusion ⅣAs arising from tricuspid annulus are not rare,and the detailed origin can be determined by ECG analysis and CARTO mapping system could be useful for an effective ablation for the ⅣAs.%目的 探讨三尖瓣环特发性室性心律失常(ⅣAs)的心电图特征及导管消融疗效.方法 对本中心在CARTO三维标测系统指导下成功行导管消融ⅣAs的临床资料进行回顾性分析.结果 ①在2011年1月至2012年12月期间,共计246例进行了三维标测指导下的导管消融术,22例ⅣAs(19例为室性早搏,3例为室性心动过速)起源于三尖瓣环,即本组三尖瓣起源ⅣAs占8.9%(22/246).其中男14例,女12例,年龄34.5±6.8岁.15例(68.2%)起源于三尖瓣环游离壁,7例(31.8%)

  5. 沿同心环面层流流动的气体中颗粒的传热沉积物的预测:发展中的流动和已充分发展的流动的比较%Prediction of Thermophoretic Deposition Efficiency of Particles in a Laminar Gas Flow along a Concentric Annulus: A Comparison of Developing and Fully Developed Flows

    Institute of Scientific and Technical Information of China (English)

    Samira Hashemi; Ataallah Soltani Goharrizi

    2009-01-01

    Thermophoresis is an important mechanism of micro-particle transport due to temperature gradients in the surrounding medium. It has numerous applications, especially in the field of aerosol technology. This study has numerically investigated the thermophoretic deposition efficiency of particles in a laminar gas flow in a concentric annulus using the critical trajectory method. The governing equations are the momentum and energy equations for the gas and the particle equations of motion. The effects of the annulus size, particle diameter, the ratio of inner to outer radius of tube and wall temperature on the deposition efficiency were studied for both developing and fully-developed flows. Simulation results suggest that thermophoretic deposition increases by increasing thermal gradient, deposition distance, and the ratio of inner to outer radius, but decreases with increasing particle size. It has been found that by taking into account the effect of developing flow at the entrance region, higher deposition efficiency was obtained, than fully developed flow.

  6. Implante de bioprótese aórtica "stentless" em pacientes com alterações do anel aórtico Aortic valve replacement with a stentless bioprosthesis in patients with weakened aortic annulus

    Directory of Open Access Journals (Sweden)

    Bayard Gontijo Filho

    1993-06-01

    Full Text Available Dezessete pacientes portadores de doença da valva aórtica associada a alterações estruturais do anel aórtico foram submetidos a implante de bioprótese aórtica "stentless" (Biocór: 8 pacientes eram portadores de endocardite bacteriana, sendo 3 em valva aórtica e 5 em próteses. Os demais pacientes eram portadores de próteses aórticas disfuncionantes. A técnica de implante foi basicamente a mesma, utilizandose dois níveis de sutura, sendo o primeiro ao nível do anel aórtico e o outro na parede aórtica. Em 11 pacientes a aorta ascendente foi ampliada com remendo de pericárdio bovino e 3 pacientes foram submetidos, também, a substituição valvar mitral. Houve 1 óbito hospitalar no 23º dia de pós-operatório por falência de múltiplos órgãos em 1 paciente portador de endocardite bacteriana e quadro de AVC pré-operatório. Dois pacientes necessitaram implante de marcapasso definitivo. Na evolução tardia houve apenas 1 óbito no 6º mês, de forma súbita, em uma criança portadora de marcapasso. Um paciente desenvolveu deiscência parcial da bioprótese na sutura inferior, o que gerou um gradiente na via de saída do ventrículo esquerdo, sendo reoperado com sucesso de 18º mês de pós-operatório. Todos os pacientes encontram-se em controle ambulatorial, com estudos ecocardiográficos seriados, que demonstram excelente desempenho da bioprótese "stentless" sem gradientes transvalvares importantes e ausência de regurgitação aórtica significativa.An aortic stentless bioprosthesis (Biocor Ind. was implanted in 17 patients with difficult aortic annulus due either to endocarditis orto a previous aortic valve replacement. Native valve endocarditis was present in 3 patients and prosthetic valve endocarditis in 5; 9 patients had one or more previous aortic valve replacements showing a wheakened aortic rim. The stentless bioprosthesis was implanted with a two layers suture technique similar to a homograft implant. The

  7. 水平井偏心环空顶替流体密度差优化%Density difference optimization of displacing lfuids in eccentric annulus of horizontal wells

    Institute of Scientific and Technical Information of China (English)

    冯福平; 艾池; 崔志华; 于法浩; 陈顶峰; 徐海粟

    2014-01-01

    length slows down with time increasing, but it is not obvious; the too large or small density difference will reduce the displacement interface stability in the eccentric annulus of horizontal wells. In order to achieve the shortest displacement interface length in cementing, reasonable density difference shall be chosen on the basis of casing eccentricity. The study results provides theoretical basis for the design of displacement parameters and cementing length in horizontal wells.

  8. Use of Temporary Implantable Biomaterials to Reduce Leg Pain and Back Pain in Patients with Sciatica and Lumbar Disc Herniation

    Directory of Open Access Journals (Sweden)

    Gere S. diZerega

    2010-05-01

    Full Text Available The principle etiology of leg pain (sciatica from lumbar disc herniation is mechanical compression of the nerve root. Sciatica is reduced by decompression of the herniated disc, i.e., removing mechanical compression of the nerve root. Decompression surgery typically reduces sciatica more than lumbar back pain (LBP. Decompression surgery reduces mechanical compression of the nerve root. However, decompression surgery does not directly reduce sensitization of the sensory nerves in the epidural space and disc. In addition, sensory nerves in the annulus fibrosus and epidural space are not protected from topical interaction with pain mediators induced by decompression surgery. The secondary etiology of sciatica from lumbar disc herniation is sensitization of the nerve root. Sensitization of the nerve root results from a mechanical compression, b exposure to cellular pain mediators, and/or c exposure to biochemical pain mediators. Although decompression surgery reduces nerve root compression, sensory nerve sensitization often persists. These observations are consistent with continued exposure of tissue in the epidural space, including the nerve root, to increased cellular and biochemical pain mediators following surgery. A potential contributor to lumbar back pain (LBP is stimulation of sensory nerves in the annulus fibrosus by a cellular pain mediators and/or b biochemical pain mediators that accompany annular tears or disruption. Sensory fibers located in the outer one-third of the annulus fibrosus increase in number and depth as a result of disc herniation. The nucleus pulposus is comprised of material that can produce an autoimmune stimulation of the sensory nerves located in the annulus and epidural space leading to LBP. The sensory nerves of the annulus fibrosus and epidural space may be sensitized by topical exposure to cellular and biochemical pain mediators induced by lumbar surgery. Annulotomy or annular rupture allows the nucleus pulposus

  9. Radiological Consequence Analysis of Annulus Ventilation System with Delayed Operation under Severe Accident of Nuclear Power Plants%核电厂严重事故下双层安全壳环形空间通风系统延迟投运的放射性后果影响分析

    Institute of Scientific and Technical Information of China (English)

    吴楠; 黄树明; 刘新建

    2016-01-01

    During severe accidents, forthenuclear power plants ( NPPs) with double⁃containment design, ifa sub⁃atmospheric pressure cannot be built or the accident filter cannot be activated when annulus ventila⁃tion system is failed to operate normally, the control function of fission⁃product releaseof dual containment would be weakened�With focus on the double⁃containment design adopted by most of the Gen-ⅢNPPs in the world, this paper firstly calculates the release amountof radioactive materialsinto environment under different delay scenarios of annulus ventilation systemoperation, with the consideration of the intact con⁃tainment and using NUREG-1465 source term� Then the Criteria for Limited Impact ( CLI) provided in European Utility Requirements ( EUR) areare applied to evaluateradiological consequence of severe acci⁃dent, and the relationship between the delay of annulus ventilation systemoperation and “large release” is analyzed� The results could beareference for the emergency response actions and radiological consequence estimation in the context of severe accidents.%核电厂严重事故工况下,对于具有双层安全壳设计的核电机组,若环形空间通风系统不能正常运转,无法形成负压或无法启动事故过滤器,双层安全壳对放射性物质释放的控制效果将被削弱。鉴于此,本文针对目前国际上多个第三代核电机组采用的双层安全壳设计,考虑安全壳完整并选用NUREG-1465源项作为严重事故源项,计算环形空间通风系统在不同延迟投运场景下放射性物质的环境释放量,同时采用“欧洲用户要求( EUR)”文件提出的有限影响准则对严重事故的放射性后果进行评价,分析环形空间通风系统的延迟投运同“大量释放”间的关系。研究结果可为严重事故下的应急响应行动及放射性后果评价提供参考。

  10. Polyurethane scaffold with in situ swelling capacity for nucleus pulposus replacement.

    Science.gov (United States)

    Li, Zhen; Lang, Gernot; Chen, Xu; Sacks, Hagit; Mantzur, Carmit; Tropp, Udi; Mader, Kerstin T; Smallwood, Thomas C; Sammon, Chris; Richards, R Geoff; Alini, Mauro; Grad, Sibylle

    2016-04-01

    Nucleus pulposus (NP) replacement offers a minimally invasive alternative to spinal fusion or total disc replacement for the treatment of intervertebral disc (IVD) degeneration. This study aimed to develop a cytocompatible NP replacement material, which is feasible for non-invasive delivery and tunable design, and allows immediate mechanical restoration of the IVD. A bi-phasic polyurethane scaffold was fabricated consisting of a core material with rapid swelling property and a flexible electrospun envelope. The scaffold was assessed in a bovine whole IVD organ culture model under dynamic load for 14 days. Nucleotomy was achieved by incision through the endplate without damaging the annulus fibrosus. After implantation of the scaffold and in situ swelling, the dynamic compressive stiffness and disc height were restored immediately. The scaffold also showed favorable cytocompatibility for native disc cells. Implantation of the scaffold in a partially nucleotomized IVD down-regulated catabolic gene expression, increased proteoglycan and type II collagen intensity and decreased type I collagen intensity in remaining NP tissue, indicating potential to retard degeneration and preserve the IVD cell phenotype. The scaffold can be delivered in a minimally invasive manner, and the geometry of the scaffold post-hydration is tunable by adjusting the core material, which allows individualized design.

  11. Hibiscus chlorotic ringspot virus coat protein is essential for cell-to-cell and long-distance movement but not for viral RNA replication.

    Directory of Open Access Journals (Sweden)

    Shengniao Niu

    Full Text Available Hibiscus chlorotic ringspot virus (HCRSV is a member of the genus Carmovirus in the family Tombusviridae. In order to study its coat protein (CP functions on virus replication and movement in kenaf (Hibiscus cannabinus L., two HCRSV mutants, designated as p2590 (A to G in which the first start codon ATG was replaced with GTG and p2776 (C to G in which proline 63 was replaced with alanine, were constructed. In vitro transcripts of p2590 (A to G were able to replicate to a similar level as wild type without CP expression in kenaf protoplasts. However, its cell-to-cell movement was not detected in the inoculated kenaf cotyledons. Structurally the proline 63 in subunit C acts as a kink for β-annulus formation during virion assembly. Progeny of transcripts derived from p2776 (C to G was able to move from cell-to-cell in inoculated cotyledons but its long-distance movement was not detected. Virions were not observed in partially purified mutant virus samples isolated from 2776 (C to G inoculated cotyledons. Removal of the N-terminal 77 amino acids of HCRSV CP by trypsin digestion of purified wild type HCRSV virions resulted in only T = 1 empty virus-like particles. Taken together, HCRSV CP is dispensable for viral RNA replication but essential for cell-to-cell movement, and virion is required for the virus systemic movement. The proline 63 is crucial for HCRSV virion assembly in kenaf plants and the N-terminal 77 amino acids including the β-annulus domain is required in T = 3 assembly in vitro.

  12. Preliminary Effect of Tricuspid Annuloplasty for Patients with Dilated Tricuspid Annulus and Left-sided Heart Valve Surgery by Employing Combined Bicuspidization and Modified Kay Annuloplasty%联合二瓣化和改良Kay成形术处理左心瓣膜手术患者三尖瓣瓣环扩张的初步疗效观察

    Institute of Scientific and Technical Information of China (English)

    肖锡俊; 蒋露; 李永波; 唐红; 周文霞; 朱蔚

    2012-01-01

    Objective To evaluate the preliminary effect of tricuspid annuloplasty for patients with dilated tricuspid annulus and left-sided heart valve surgery by employing combined bicuspidization and modified Kay annuloplasty. Methods Combined bicuspidization and modified Kay annuloplasty were performed in 158 patients with dilated tricuspid annulus (tricuspid annulus diameter/body surface area ≥21 mm/m2) and left-sided heart valve surgery in West China Hospital between January 2010 and May 2011. There were 27 male and 131 female patients whose age ranged from 17 to 74 (45. 9± 10. 4) years. A total of 92 patients had atrial fibrillation and 66 patients were in sinus rhythm. The severity of tricuspid regurgitation (TR) was graded 0 through 5 as determined by echocardiography. Results All the patients recovered from surgery and were discharged from hospital. The average cardiopulmonary bypass time was 100.8±30.5( range, 54 to 273) min, and the average aortic cross clamping time was 64. 5 ± 22. 0 (range, 25 to 162)min. The average lowest esophageal temperature during aortic cross clamping was 28. 5 ± 1. 1 (range, 26. 3 to 34. 1)℃ . The average postoperative follow-up was 11. 0 ± 5. 0 ( range, 3 to 19 ) months. The postoperative TR severity was significantly lower than preoperative TR severity (2. 2±1. 3 versus 0. 4±0. 8, P 0.05). Conclusion It is reasonable to perform tricuspid annuloplasty for patients with dilated tricuspid annulus and left-sided heart valve surgery according to their index of tricuspid annulus diameter/body surface area (≥ 21 mm/m2). To prevent postoperative residue or progression of TR in patients with dilated tricuspid annulus, it is effective to employ combined bicuspidization and modified Kay annuloplasty.%目的 观察用联合二瓣化和改良Kay成形术处理左心瓣膜手术患者三尖瓣瓣环扩张的临床结果. 方法 回顾性分析2010年1月至2011年5月华西医院158例伴有三尖瓣瓣环扩张(三

  13. Foxa1 and Foxa2 are required for formation of the intervertebral discs.

    Directory of Open Access Journals (Sweden)

    Jennifer A Maier

    Full Text Available The intervertebral disc (IVD is composed of 3 main structures, the collagenous annulus fibrosus (AF, which surrounds the gel-like nucleus pulposus (NP, and hyaline cartilage endplates, which are attached to the vertebral bodies. An IVD is located between each vertebral body. Degeneration of the IVD is thought to be a major cause of back pain, a potentially chronic condition for which there exist few effective treatments. The NP forms from the embryonic notochord. Foxa1 and Foxa2, transcription factors in the forkhead box family, are expressed early during notochord development. However, embryonic lethality and the absence of the notochord in Foxa2 null mice have precluded the study of potential roles these genes may play during IVD formation. Using a conditional Foxa2 allele in conjunction with a tamoxifen-inducible Cre allele (ShhcreER(T2, we removed Foxa2 from the notochord of E7.5 mice null for Foxa1. Foxa1(-/-;Foxa2(c/c;ShhcreER(T2 double mutant animals had a severely deformed nucleus pulposus, an increase in cell death in the tail, decreased hedgehog signaling, defects in the notochord sheath, and aberrant dorsal-ventral patterning of the neural tube. Embryos lacking only Foxa1 or Foxa2 from the notochord were indistinguishable from control animals, demonstrating a functional redundancy for these genes in IVD formation. In addition, we provide in vivo genetic evidence that Foxa genes are required for activation of Shh in the notochord.

  14. Morphologic features of spontaneous annular tears and disc degeneration in the aging sand rat (Psammomys obesus obesus).

    Science.gov (United States)

    Gruber, H E; Hanley, E N

    2017-08-11

    The sand rat, a member of the gerbil family, is a valuable small animal model in which intervertebral disc degeneration occurs spontaneously as the animal ages. Radiographic features of cervical and lumbar degeneration resemble those in human spines. We conducted a retrospective analysis of spines of 140 animals 3-41 months old focusing specifically on the presence of annular tears that are not visible by radiography and have not been described previously in the sand rat disc. During degeneration of the nucleus pulposus, notochordal cell death occurs and granular material, which stains with Alcian blue for proteoglycans, accumulates. Lamellar architecture also deteriorates and annular tears occur that are morphologically similar to the concentric, radiating and transdiscal annular tears in human discs. These tears contain granular material that provides a "marker" that can be used to distinguish the annular tears from artefactual separations during sectioning. We observed lamellar degeneration and separation in the annulus fibrosus at 4 months with associated tears that contained granular material in the nucleus. Tears that contained granular material and displacement of the degenerating nucleus were common in cervical and lumbar discs of animals older than 9 months; some specimens showed tears at 4 and 5 months. With advanced degeneration, granular globules were displaced dorsally adjacent to and into the spinal cord area and also ventrally into regions where osteophytes formed. We present morphologic data that expand the utility of this rodent model of spontaneous age-related disc degeneration and provide novel information on annular tears and disc degeneration.

  15. The effects of mechanical forces on bones and joints. Experimental study on the rat tail.

    Science.gov (United States)

    Pazzaglia, U E; Andrini, L; Di Nucci, A

    1997-11-01

    We have used an experimental model employing the bent tail of rats to investigate the effects of mechanical forces on bones and joints. Mechanical strain could be applied to the bones and joints of the tail without direct surgical exposure or the application of pins and wires. The intervertebral disc showed stretched annular lamellae on the convex side, while the annulus fibrosus on the concave side was pinched between the inner corners of the vertebral epiphysis. In young rats with an active growth plate, a transverse fissure appeared at the level of the hypertrophic cell layer or the primary metaphyseal trabecular zone. Metaphyseal and epiphyseal trabeculae on the compressed side were thicker and more dense than those of the distracted part of the vertebra. In growing animals, morphometric analysis of hemiepiphyseal and hemimetaphyseal areas, and the corresponding trabecular bone density, showed significant differences between the compressed and distracted sides. No differences were observed in adult rats. We found no significant differences in osteoclast number between compressed and distracted sides in either age group. Our results provide quantitative evidence of the working of 'Wolff's law'. The differences in trabecular density are examples of remodelling by osteoclasts and osteoblasts; our finding of no significant difference in osteoclast numbers between the hemiepiphyses in the experimental and control groups suggests that the response of living bone to altered strain is mediated by osteoblasts.

  16. The presence and absence of lymphatic vessels in the adult human intervertebral disc: relation to disc pathology

    Energy Technology Data Exchange (ETDEWEB)

    Kliskey, Karolina; Williams, Kelly; Yu, J.; Urban, Jill; Athanasou, Nick [University of Oxford, Nuffield Department of Orthopaedic, Rheumatology and Musculoskeletal Science, Oxford (United Kingdom); Jackson, David [Weatherall Institute of Molecular Medicine, Human Immunology Unit, Oxford (United Kingdom)

    2009-12-15

    Although the normal adult human intervertebral disc is considered to be avascular, vascularised cellular fibrous tissue can be found in pathological conditions involving the disc such as disc herniation. Whether lymphatics vessels form a component of this reparative tissue is not known as the presence or absence of lymphatics in herniated and normal disc tissue is not known. We examined spinal tissues and discectomy specimens for the presence of lymphatics. The examination used immunohistochemistry to identify the specific lymphatic endothelial cell markers, podoplanin and LYVE1. Lymphatic vessels were not found in the nucleus pulposus or annulus fibrosus of intact, non-herniated lumbar and thoracic discs but were present in the surrounding ligaments. Ingrowth of fibrous tissue was seen in 73% of herniated disc specimens of which 36% contained LYVE1+/podoplanin + lymphatic vessels. Lymphatic vessels were not seen in the sacrum and coccyx or biopsies of four sacrococcygeal chordomas, but they were noted in surrounding extra-osseous fat and fibrous tissue at the edge of the infiltrating tumour. Our findings indicate that lymphatic vessels are not present in the normal adult intervertebral disc but that, when there is extrusion of disc material into surrounding soft tissue, there is ingrowth of reparative fibrous tissue containing lymphatic vessels. Our findings also indicate that chordoma, a tumour of notochordal origin, spreads to regional lymph nodes via lymphatics in para-spinal soft tissues. (orig.)

  17. Ultrastructure of Intervertebral Disc and Vertebra-Disc Junctions Zones as a Link in Etiopathogenesis of Idiopathic Scoliosis

    Directory of Open Access Journals (Sweden)

    Evalina L. Burger

    2014-01-01

    Full Text Available Background Context. There is no general accepted theory on the etiology of idiopathic scoliosis (IS. An important role of the vertebrae endplate physes (VEPh and intervertebral discs (IVD in spinal curve progression is acknowledged, but ultrastructural mechanisms are not well understood. Purpose. To analyze the current literature on ultrastructural characteristics of VEPh and IVD in the context of IS etiology. Study Design/Setting. A literature review. Results. There is strong evidence for multifactorial etiology of IS. Early wedging of vertebra bodies is likely due to laterally directed appositional bone growth at the concave side, caused by a combination of increased cell proliferation at the vertebrae endplate and altered mechanical properties of the outer annulus fibrosus of the adjacent IVD. Genetic defects in bending proteins necessary for IVD lamellar organization underlie altered mechanical properties. Asymmetrical ligaments, muscular stretch, and spine instability may also play roles in curve formation. Conclusions. Development of a reliable, cost effective method for identifying patients at high risk for curve progression is needed and could lead to a paradigm shift in treatment options. Unnecessary anxiety, bracing, and radiation could potentially be minimized and high risk patient could receive surgery earlier, rendering better outcomes with fewer fused segments needed to mitigate curve progression.

  18. Aquaporin-1 and Aquaporin-3 Expressions in the Intervertebral Disc of Rats with Aging

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    Mustafa Sarsılmaz

    2012-12-01

    Full Text Available Objective: The intervertebral disc (IVD undergoes biochemical and morphologic degenerative changes during the process of aging. Aquaporins (AQPs are a family of water channel proteins that facilitate water and small solute movement in tissues and may have a potential role in the aging degeneration of IVDs. One of the important problems in understanding disc degeneration is to find cellular molecules which contribute to the pathogenesis of IVDs. XThe aim of this study was to demonstrate the expression of aquaporin 1 and 3 in nucleus pulposus (NP, annulus fibrosus (AF cells of rat lumbar intervertebral discs from both young and aged animals using immunohistochemistry.Material and Methods: Twenty Wistar-albino rats were included in the study. The rats were separated into two groups: 2-month-old rats (n=10 as the young group, 18-month-old rats (n=10 as the old group. The intervertebral disc tissues obtained from the lumbar spine (L1–L4, 4 discs were used for immunohistochemical staining of AQP-1 and 3. Results: This study demonstrated that AQP-1 and AQP-3 immunoreactivity significantly decreased in NP and AF of aged rats compared to the young rats. Conclusion: We suggest that AQP-1 and 3 may contribute to the age related degeneration of the intervertebral disc.

  19. On the collagen criss-cross angles in the annuli fibrosi of lumbar spine finite element models.

    Science.gov (United States)

    Noailly, Jérôme; Planell, Josep A; Lacroix, Damien

    2011-04-01

    In the human lumbar spine, annulus fibrosus fibres largely contribute to intervertebral disc stability. Detailed annulus models are therefore necessary to obtain reliable predictions of lumbar spine mechanics by finite element modelling. However, different definitions of collagen orientations coexist in the literature for healthy human lumbar annuli. Therefore, four annulus fibre-induced anisotropy models were built from reported anatomical descriptions, and inserted in a L3-L5 lumbar bi-segment finite element model. Annulus models were, respectively, characterized by radial, tangential, radial and tangential, and no fibre orientation gradients. The effect of rotational and axial compressive loadings was simulated and first, predictions were compared to experimental data. Then, intervertebral disc local biomechanics was studied under axial rotation and axial compression. A new parameter, i.e. the fibre contribution quality parameter, was computed in the anterior, lateral, postero-lateral, and posterior annuli of each model, in function of fibre stresses, radial load distributions, and matrix shear strains. Locally, each annulus model behaved differently, affecting intervertebral disc biomechanics and segmental motions. The fibre contribution quality parameter allowed establishing direct links between local annulus fibre organization and local annulus loadings, while other kinematical and biomechanical data did not. It was concluded that functional relations should exist between local annulus fibre orientations and overall segment morphology. The proposed fibre contribution quality parameter could be used to examine such relations and calibrate lumbar spine finite element models by locally adjusting the annulus bundle criss-cross angles. Conclusions of this study are particularly relevant to patient-specific models or artificial disc designs.

  20. Assessment of intermediate-term outcomes of aortic valve replacement with enlargement of aortic annulus by changes in effective orifice area index%动态有效瓣口面积指数对扩大瓣环主动脉瓣置换术中期临床效果的评价

    Institute of Scientific and Technical Information of China (English)

    朱亚彬; 朱兵; 杨岷; 石维平; 王宁夫; K.M.Cherian; 刘志勇

    2012-01-01

    Objectives To asses the intermediate-term clinical outcomes by changes in effective orifice area index (EOAI)in patients with small aortic annulus who received aortic valve replacement (AVR) enlargement of aortic annulus using two kinds of operations. Methods Thirty patients received AVR with enlargement of aortic annulus using Konno operation and Manougnian's operation were included in this study. Electrocardiogram (ECG), echocardiography (UCG), clinical symptom and changes of EOAI in Konno operation group and Manougnian's operation group were reviewed and compared with those in control patients received ordinary AVR during the same period. Results Twelve patients were in Konno operation group and 18 in Manougnian's operation group. At the prophase stage,case fatality rate of enlargement operation was 3.33%, incidence rate of arrhythmia was 76.3% and incidence rate of low cardiac output syndrome was 34.1%. They were followed up for 21 - 109 months with follow up rate of 100%. There was no significant difference in regression of left ventricular wall thickness, mass index and mean transvalvular gradients between Konno operation group and Manougnian's operation group after 3 years(P>0.05). There were no differences in 1-year survival rate and 3-year survival rate between enlargement operation group and ordinary operationro group(96.5% vs. 96.5%,P= 0.23; 86.2% vs. 89.65% ,P=0.14). The 3-year survival rates between Konno operation group and Manougnian's operation group had no significant difference (91.6% vs. 88.23% ,P>0.05). Difference in duration of operation and incidence of bundle-branch damage between enlargement operation group and ordinary operation group was significant (P<0.05). Values of EOAI in Konna group and Manougnian's group were higher than that in ordinary operation group, and it was higher in Konna group than in Manougnian's group. The differenes were significant(P<0.05). Incidence rate of dalated prosthesis-patient mismatch (DPPM) in Konno operation

  1. Intervertebral Disc Tissue Engineering with Natural Extracellular Matrix-Derived Biphasic Composite Scaffolds.

    Directory of Open Access Journals (Sweden)

    Baoshan Xu

    Full Text Available Tissue engineering has provided an alternative therapeutic possibility for degenerative disc diseases. However, we lack an ideal scaffold for IVD tissue engineering. The goal of this study is to fabricate a novel biomimetic biphasic scaffold for IVD tissue engineering and evaluate the feasibility of developing tissue-engineered IVD in vitro and in vivo. In present study we developed a novel integrated biphasic IVD scaffold using a simple freeze-drying and cross-linking technique of pig bone matrix gelatin (BMG for the outer annulus fibrosus (AF phase and pig acellular cartilage ECM (ACECM for the inner nucleus pulposus (NP phase. Histology and SEM results indicated no residual cells remaining in the scaffold that featured an interconnected porous microstructure (pore size of AF and NP phase 401.4 ± 13.1 μm and 231.6 ± 57.2 μm, respectively. PKH26-labeled AF and NP cells were seeded into the scaffold and cultured in vitro. SEM confirmed that seeded cells could anchor onto the scaffold. Live/dead staining showed that live cells (green fluorescence were distributed in the scaffold, with no dead cells (red fluorescence being found. The cell-scaffold constructs were implanted subcutaneously into nude mice and cultured for 6 weeks in vivo. IVD-like tissue formed in nude mice as confirmed by histology. Cells in hybrid constructs originated from PKH26-labeled cells, as confirmed by in vivo fluorescence imaging system. In conclusion, the study demonstrates the feasibility of developing a tissue-engineered IVD in vivo with a BMG- and ACECM-derived integrated AF-NP biphasic scaffold. As well, PKH26 fluorescent labeling with in vivo fluorescent imaging can be used to track cells and analyse cell--scaffold constructs in vivo.

  2. Clinical Analysis an 234 Cases of Adolescents with Small Aortic Annulus Aortic Valve Disease Surgical Operation Effect%234例青少年小主动脉瓣环主动脉瓣病变外科手术效果的临床分析

    Institute of Scientific and Technical Information of China (English)

    刘光强; 张丽; 何勇; 许发珍; 王茂生; 李中杰; 陈冲; 邱龙兴

    2014-01-01

    Objective To explore the clinical analysis of surgical operation effect of adolescent small aortic annulus aortic valve disease, and to guide clinical practice and clinical effect. Methods In our hospital in small aortic annulus aortic valve disease in adolescent patients with 234 cases, were randomly divided into two groups with 117 cases in each group, to observe the application of aortic valve replacement and annulus enlargement, including 25 cases of Nicks, 36 cases of Konno, 56 cases in group C were treated by Ross, the control group received traditional operation therapy, echocardiography evaluation of cardiac function after operation, two groups to improve the situation and the operation parameter index. Results The patients were followed up for 1-3 years, left ventricular mass index, observation group, posterior wall thickness, the aortic transvalvular pressure difference were significantly better than control group(P<0.05);improve heart function class NYHA has two groups after treatment, but NYHA cardiac function grade observation group improved more significantly than the control group(P<0.05). Conclusion Aortic valve replacement and mitral annular dilation operation, can effectively improve the success rate of operation, rapid postoperative recovery, promote growth, improve the quality of life of patients, increase the survival rate, clinical effect, is worth the clinical promotion.%目的:探讨青少年小主动脉瓣环主动脉瓣病变的外科手术效果临床分析,以指导临床实践及临床疗效。方法入选我院小主动脉瓣环主动脉瓣病变青少年患者234例,随机分为两组各117例,观察组应用主动脉瓣置换术同时行瓣环扩大术,其中25例行Nicks法,36例行Konno法,C组56例行Ross法,对照组进行施行传统单纯换瓣膜手术疗法(主动脉瓣环不扩大),术后复查心脏彩超,评估两组的心功能改善情况及各手术参数指标情况。结果术后随访1~3年

  3. Specimen specific parameter identification of ovine lumbar intervertebral discs: On the influence of fibre-matrix and fibre-fibre shear interactions.

    Science.gov (United States)

    Reutlinger, Christoph; Bürki, Alexander; Brandejsky, Vaclav; Ebert, Lars; Büchler, Philippe

    2014-02-01

    Numerical models of the intervertebral disc, which address mechanical questions commonly make use of the difference in water content between annulus and nucleus, and thus fluid and solid parts are separated. Despite this simplification, models remain complex due to the anisotropy and nonlinearity of the annulus and regional variations of the collagen fibre density. Additionally, it has been shown that cross-links make a large contribution to the stiffness of the annulus. Because of this complex composite structure, it is difficult to reproduce several sets of experimental data with one single set of material parameters. This study addresses the question to which extent the ultrastructure of the intervertebral disc should be modelled so that its moment-angle behaviour can be adequately described. Therefore, a hyperelastic constitutive law, based on continuum mechanical principles was derived, which does not only consider the anisotropy from the collagen fibres, but also interactions among the fibres and between the fibres and the ground substance. Eight ovine lumbar intervertebral discs were tested on a custom made spinal loading simulator in flexion/extension, lateral bending and axial rotation. Specimen-specific geometrical models were generated using CT images and T2 maps to distinguish between annulus fibrosus and nucleus pulposus. For the identification of the material parameters the annulus fibrosus was described with two scenarios: with and without fibre-matrix and fibre-fibre interactions. Both scenarios showed a similar behaviour on a load displacement level. Comparing model predictions to the experimental data, the mean RMS of all specimens and all load cases was 0.54±0.15° without the interaction and 0.54±0.19° when the fibre-matrix and fibre-fibre interactions were included. However, due to the increased stiffness when cross-links effects were included, this scenario showed more physiological stress-strain relations in uniaxial and biaxial stress

  4. Application of real-time three-dimensional transesphaogeal echocardiography in quantitation of tricuspid valve annulus diameter%经食管实时三维超声心动图对三尖瓣环径测量位点的研究

    Institute of Scientific and Technical Information of China (English)

    孔令秋; 康彧; 唐红; 张尔永; 肖锡俊; 郭应强; 宋海波

    2013-01-01

    Objective To verify the feasibility and accuracy in the measurement of tricuspid valve annulus diameter(TVD) in the right ventricular outflow tract view.Methods Seventy five patients under the valve replacement surgery for the left heart valve lesions were divided into mild,moderate and severe group according to the severity of the regurgitation.The TVD was get on the apical four-chamber heart viewpreoperatively by transthoracic echocardiography(TTE),noted as TTE-TVD,meanwhile it was also get by the transesophageal echocardiography on the four-chamber view (TEE-TVD),right ventricular inflow (RVIT-TVD) and outflow tract view(RVOT-TVD).The changes of tricuspid regurgitation severtity was observed preoperatively.And the morphology of tricuspid annulus were observed using both real-time three dimensional transesophageal echocardiography (RT-3D TEE) and the quantitative software.Results Comparison in the groups:no statistically significant difference (P >0.05) was found between TTE-TVD,TEE-TVD and RVIT-TVD;while the RVOT-TVD was significant greater than that in the same group from other views (P < 0.05).Comparison between the groups:no significant difference was found between mild and moderate regurgitation group on the same view.There was a significant difference of the TVD between the severe regurgitation group and the former two groups on each view(P <0.05).The severity of tricuspid regurgitation in intraoperative anesthesia was reduced.The "saddle" tricuspid ring evolved into the narrow planar structure on the RT-3D TEE.For the expansion of the annulus,it departure from the tricuspid septal leaflet.Conclusions TVD measured on the right ventricular outflow tract view reflect the maximum expansion of the tricuspid valve annulus diameter,and can effectively guide the decision-making choices of the surgeon.%目的 探讨在右室流出道切面测量三尖瓣环径(TVD)的可行性与准确性.方法 75例因左心瓣膜损害而行瓣膜置换术患者,根据

  5. Erg cooperates with TGF-β to control mesenchymal differentiation.

    Science.gov (United States)

    Cox, Megan K; Appelboom, Brittany L; Ban, Ga I; Serra, Rosa

    2014-11-01

    Transforming growth factor β (TGF-β) signaling plays an integral role in skeletal development. Conditional deletion of the TGF-β type II receptor (Tgfbr2) from type II Collagen (Col2a) expressing cells results in defects in development of the annulus fibrosus (AF) of the intervertebral disc (IVD). We previously used microarray analysis to search for marker genes of AF as well as transcription factors regulated by TGF-β during AF development. The transcription factor avian erythroblastosis virus E-26 (v-ets) oncogene related (Erg) was identified in the microarray screen as a candidate regulator of AF development. To study the effects of TGF-β on AF differentiation and the role of Erg in this process, we used mouse sclerotome grown in micromass cultures. At 0.5ng TGF-β/ml, sclerotome cells started to express markers of AF. Regulation of Erg by TGF-β was confirmed in these cells. In addition, TGF-β soaked Affi-gel beads implanted into the axial skeleton of stage HH 25 chick embryos showed that TGF-β could induce expression of Erg mRNA in vivo. Next, an adenovirus to over-express Erg in primary sclerotome micromass cultures was generated. Over-expression of Erg led to a change in cell morphology and inhibition of differentiation into hyaline cartilage as seen by reduced Alcian blue staining and decreased Sox9 and c-Maf expression. Erg was not sufficient to induce expression of AF markers and expression of Sca1, a marker of pluripotent progenitor cells, was up-regulated in Erg expressing cells. When cells that ectopically expressed Erg were treated with TGF-β, enhanced expression of specific differentiation markers was observed suggesting Erg can cooperate with TGF-β to regulate differentiation of the sclerotome. Furthermore, we showed using co-immunopreciptiation that Erg and Smad3 bind to each other suggesting a mechanism for their functional interaction.

  6. A role for TNFα in intervertebral disc degeneration: A non-recoverable catabolic shift

    Energy Technology Data Exchange (ETDEWEB)

    Purmessur, D.; Walter, B.A. [Leni and Peter W. May Department of Orthopaedics, Icahn School of Medicine at Mount Sinai, New York, NY 10029 (United States); Roughley, P.J. [Shriners Hospital for Children, Montreal, QC (Canada); Laudier, D.M.; Hecht, A.C. [Leni and Peter W. May Department of Orthopaedics, Icahn School of Medicine at Mount Sinai, New York, NY 10029 (United States); Iatridis, James, E-mail: james.iatridis@mssm.edu [Leni and Peter W. May Department of Orthopaedics, Icahn School of Medicine at Mount Sinai, New York, NY 10029 (United States)

    2013-03-29

    Highlights: ► TNFα induced catabolic changes similar to human intervertebral disc degeneration. ► The metabolic shift induced by TNFα was sustained following removal. ► TNFα induced changes suggestive of cell senescence without affecting cell viability. ► Interventions are required to stimulate anabolism and increase cell proliferation. -- Abstract: This study examines the effect of TNFα on whole bovine intervertebral discs in organ culture and its association with changes characteristic of intervertebral disc degeneration (IDD) in order to inform future treatments to mitigate the chronic inflammatory state commonly found with painful IDD. Pro-inflammatory cytokines such as TNFα contribute to disc pathology and are implicated in the catabolic phenotype associated with painful IDD. Whole bovine discs were cultured to examine cellular (anabolic/catabolic gene expression, cell viability and senescence using β-galactosidase) and structural (histology and aggrecan degradation) changes in response to TNFα treatment. Control or TNFα cultures were assessed at 7 and 21 days; the 21 day group also included a recovery group with 7 days TNFα followed by 14 days in basal media. TNFα induced catabolic and anti-anabolic shifts in the nucleus pulposus (NP) and annulus fibrosus (AF) at 7 days and this persisted until 21 days however cell viability was not affected. Data indicates that TNFα increased aggrecan degradation products and suggests increased β-galactosidase staining at 21 days without any recovery. TNFα treatment of whole bovine discs for 7 days induced changes similar to the degeneration processes that occur in human IDD: aggrecan degradation, increased catabolism, pro-inflammatory cytokines and nerve growth factor expression. TNFα significantly reduced anabolism in cultured IVDs and a possible mechanism may be associated with cell senescence. Results therefore suggest that successful treatments must promote anabolism and cell proliferation in

  7. Laser-induced activation of regeneration processes in spine disc cartilage

    Science.gov (United States)

    Sobol, Emil N.; Vorobjeva, Natalia N.; Sviridov, Alexander P.; Omelchenko, Alexander I.; Baskov, Andrey V.; Shekhter, Anatoliy B.; Baskov, Vladimir A.; Feldchtein, Felix I.; Kamensky, Vladislav A.; Kuranov, Roman V.

    2000-05-01

    The effect of laser radiation on the regeneration processes in spine disk cartilage has been studied in-vivo. We used rabbits as a model and a Holmium (2.09 micrometer) and an Erbium fiber (1.56 micrometer) lasers for irradiation the discs which were preliminary opened to remove annulus fibrosus and the nucleus pulposus of the intervertebral disc. The irradiated zone has been examined using an optical coherent tomography in one month after the operation and conventional histological technique in two months after the laser operation. It has been shown that laser radiation promotes the growth of the new cartilaginous tissue of fibrous and hyaline types.

  8. Individualized treatment prevents patient-prosthesis mismatch after aortic valve replacement with small aortic annulus%个体化治疗预防小主动脉瓣环瓣膜置换后瓣膜与患者的不匹配

    Institute of Scientific and Technical Information of China (English)

    韩劲松; 王辉山; 尹宗涛; 王婷婷; 韩宏光; 宋恒昌; 金岩

    2014-01-01

    BACKGROUND:It is so difficult to have aortic valve replacement with smal aortic annulus. Improper treatment may lead to patients with valvular mismatch phenomenon, and thus make left ventricular outflow tract obstruction, increase transvalvular pressures, cause cardiac hypertrophy secondary to increased left ventricular afterload and even congestive heart failure. OBJECTIVE:To summarize the treatment strategy for preventing valvular mismatch phenomenon caused by smal aortic annulus after aortic valve replacement. METHODS:Eighty-five patients with smal aortic annulus underwent aortic valve replacement surgery. 19 mm SJM Regent valve was applied to the patients with orifice diameter>17 ≤ 19 mm;to the adult patients with orifice diameter ≤ 17 mm, we performed bovine pericardial patch enlargement of the smal aortic annulus and valve replacement using 19 mm SJM Regent valve. For those with orifice diameter>19 ≤ 21 mm, we selected 21 mm Hancock II ultra biological valve for valve replacement. Effective orifice area index, left ventricular mass index, inter-ventricular septal thickness, left ventricular wal thickness, trans-valvular peak velocity, the pressure difference across the valve and trans-valvular mean pressure were measured through echocardiography. After discharge, patients were fol owed up in out-patient clinic and evaluated regularly by echocardiography. RESULTS AND CONCLUSION:There were no early deaths after operation and al cases were cured and discharged. Fol ow-up time was between 6 months and 3 years. The main complications included low cardiac output syndrome in two cases, reoperation due to bleeding in one case, and ventilator dependence in two cases. No cases occurred in cerebral complications such as cerebral hemorrhage or cerebral thrombosis, and no valvular dysfunction or card flap appeared. There was no bovine pericardium tearing, thrombosis, calcification, tumor-like bulge, infection or immune reactions. A total of 81 cases were fol owed

  9. 经右锁骨下静脉途径导管射频消融三尖瓣环下的室性心律失常%Trans-subclavian approach for radiofrequency ablation of ventricular arrhythmias originating from subtricuspid annulus

    Institute of Scientific and Technical Information of China (English)

    李腾; 詹贤章; 吴书林; 杨平珍; 薛玉梅; 方咸宏; 廖洪涛; 梁远红; 魏薇

    2012-01-01

    目的 探讨经右锁骨下静脉途径结合应用长鞘(SR0)导管射频消融三尖瓣环下起源的室性心律失常有效性及安全性.方法 8例患者,根据心电图和/或动态心电图诊断为三尖瓣环附近起源室性早搏(PVC)/室性心动过速(VT),均接受心脏电生理检查及射频消融治疗.术前曾经或术中采取常规下腔静脉途径消融失败后,改经右锁骨下静脉途径并辅用长鞘SR0进行标测与消融.消融成功后,结合靶点位置分析心电图及消融结果.结果 8例消融均获成功.根据消融导管的X线影像特征、电解剖证实其起源于三尖瓣环下6~9点.12导联体表心电图的PVC/VT的QRS波均呈左束支传导阻滞伴电轴左偏图形,Ⅰ、aVL导联主波向上,Ⅱ、Ⅲ、aVF导联主波向下,2例肢体导联见切迹,QRS波时限174.75±13.44 ms,消融靶点局部V波较体表心电图QRS波提早27.5±3.16 ms.8例成功消融靶点图只见V波,6例有峰电位.随访2 ~12个月,1例PVC复发.结论 在长鞘辅助下,经右锁骨下静脉途径能够安全、有效地消融治疗三尖瓣环下PVC/VT,是经股静脉途径消融失败的有效补充.%Objective To determine the safety and efficacy of radiofrequency catheter ablation(RFCA) of ventricular arrhythmias originating from the vicinity of the tricuspid annulus via a trans-subclavian approach and a long sheath. Methods Eight patients, who were diagnosed as frequent premature ventrieular contractions(PVC) or ventricular tachycardia(VT) by electrocardiogram or Holtor,underwent electrophysiological study and radiofrequency catheter ablation. Radiofrequency application at the earliest activation site could not abolish PVC/VT by the route femoral vein approch previous. Then, ablation catheter was introduced via the right subclavian vein by a long sheath. After a successful ablation was performed, the characteristics of electrocardiogram and results of ablation were analyzed. Results The arrhythmias were ablated

  10. 以三尖瓣瓣环径结合体表面积作为三尖瓣成形手术指征有效性的初步临床观察%Preliminary clinical observation of tricuspid annuloplasty adopting tricuspid annulus diameter and body surface area as surgical indication

    Institute of Scientific and Technical Information of China (English)

    马小五; 张平洋; 张幼祥

    2013-01-01

    目的 应用实时三维超声心动图(real-time three-dimensional echocardiography,RT-3DE)观察采用三尖瓣瓣环径结合体表面积作为三尖瓣成形术指征,是否有助于减少二尖瓣置换术(mitral valve replacement,MVR)患者术后中重度三尖瓣反流(tricuspid regurgitation,TR)的发生.方法 回顾性分析2009年3月至2011年12月我院心外科收治的118例术前TR<中度的MVR患者.术前三尖瓣瓣环径/体表面积均≥21 mm/m2,根据术中三尖瓣成形的有无和术后2年复查TR程度分为成形组(A、B亚组)和非成形组(C、D亚组),分别收集各组术前及术后2年的3-DE检查数据右心室舒张末期容积(RVEDV),右心室收缩末期容积(RVESV)及右心室毎搏量(RVSV).结果 三尖瓣成形组B组患者的术后RT-3DE指标RVEDV(124.9±23.9) ml、RVESV(59.2±11.6) ml 和RVSV(56.9±9.8) ml,三尖瓣非成形组D组患者的术后RT-3DE指标RVEDV(128.7±21.8) ml、RVESV(60.1±10.0) ml 和RVSV(57.8±10.7) ml,两者与术前RT-3DE指标比较差异均有统计学意义(P<0.05);A、B组间、C、D组间术后2年的RT-3DE指标间比较差异亦有统计学意义(P<0.01).三尖瓣非成形组术后三尖瓣中-重度反流的发生率较高.结论对术前TR<中度的MVR患者,采用三尖瓣瓣环径结合体表面积作为三尖瓣成形手术参考指标可能有效地减少这些患者术后中或重度TR的发生.%Objective To observe whether the adoptation of tricuspid annulus diameter and body surface area (BSA) as surgical indication for tricuspid annuloplasty will reduce the occurrence of moderate severe tricuspid regurgitation (TR) in patients with real-time three-dimensional echocardiography (RT-3DK) after mitral valve replacemetT(MVR). Methods Between March 2009 and December 2011, MVR was performed in 118 patients with TR<moderate and tricuspid annulus diameter/body surface area≥21 mm/m2 in the Department of our Cardiovascular Surgery. According to the adoptation of the tricuspid

  11. Simulating the sensitivity of cell nutritive environment to composition changes within the intervertebral disc

    Science.gov (United States)

    Wills, C. Ruiz; Malandrino, A.; van Rijsbergen, MM.; Lacroix, D.; Ito, K.; Noailly, J.

    2016-05-01

    Altered nutrition in the intervertebral disc affects cell viability and can generate catabolic cascades contributing to extracellular matrix (ECM) degradation. Such degradation is expected to affect couplings between disc mechanics and nutrition, contributing to accelerate degenerative processes. However, the relation of ECM changes to major biophysical events within the loaded disc remains unclear. A L4-L5 disc finite element model including the nucleus (NP), annulus (AF) and endplates was used and coupled to a transport-cell viability model. Solute concentrations and cell viability were evaluated along the mid-sagittal plane path. A design of experiment (DOE) was performed. DOE parameters corresponded to AF and NP biochemical tissue measurements in discs with different degeneration grades. Cell viability was not affected by any parameter combinations defined. Nonetheless, the initial water content was the parameter that affected the most the solute contents, especially glucose. Calculations showed that altered NP composition could negatively affect AF cell nutrition. Results suggested that AF and NP tissue degeneration are not critical to nutrition-related cell viability at early-stage of disc degeneration. However, small ECM degenerative changes may alter significantly disc nutrition under mechanical loads. Coupling disc mechano-transport simulations and enzyme expression studies could allow identifying spatiotemporal sequences related to tissue catabolism.

  12. Sensory cell proliferation within the olfactory epithelium of developing adult Manduca sexta (Lepidoptera.

    Directory of Open Access Journals (Sweden)

    Marie-Dominique Franco

    Full Text Available BACKGROUND: Insects detect a multitude of odors using a broad array of phenotypically distinct olfactory organs referred to as olfactory sensilla. Each sensillum contains one to several sensory neurons and at least three support cells; these cells arise from mitotic activities from one or a small group of defined precursor cells. Sensilla phenotypes are defined by distinct morphologies, and specificities to specific odors; these are the consequence of developmental programs expressed by associated neurons and support cells, and by selection and expression of subpopulations of olfactory genes encoding such proteins as odor receptors, odorant binding proteins, and odor degrading enzymes. METHODOLOGY/PRINCIPAL FINDINGS: We are investigating development of the olfactory epithelium of adult M. sexta, identifying events which might establish sensilla phenotypes. In the present study, antennal tissue was examined during the first three days of an 18 day development, a period when sensory mitotic activity was previously reported to occur. Each antenna develops as a cylinder with an outward facing sensory epithelium divided into approximately 80 repeat units or annuli. Mitotic proliferation of sensory cells initiated about 20-24 hrs after pupation (a.p., in pre-existing zones of high density cells lining the proximal and distal borders of each annulus. These high density zones were observed as early as two hr. a.p., and expanded with mitotic activity to fill the mid-annular regions by about 72 hrs a.p. Mitotic activity initiated at a low rate, increasing dramatically after 40-48 hrs a.p.; this activity was enhanced by ecdysteroids, but did not occur in animals entering pupal diapause (which is also ecdysteroid sensitive. CONCLUSIONS/SIGNIFICANCE: Sensory proliferation initiates in narrow zones along the proximal and distal borders of each annulus; these zones rapidly expand to fill the mid-annular regions. These zones exist prior to any mitotic activity

  13. Organ culture bioreactors--platforms to study human intervertebral disc degeneration and regenerative therapy.

    Science.gov (United States)

    Gantenbein, Benjamin; Illien-Jünger, Svenja; Chan, Samantha C W; Walser, Jochen; Haglund, Lisbet; Ferguson, Stephen J; Iatridis, James C; Grad, Sibylle

    2015-01-01

    In recent decades the application of bioreactors has revolutionized the concept of culturing tissues and organs that require mechanical loading. In intervertebral disc (IVD) research, collaborative efforts of biomedical engineering, biology and mechatronics have led to the innovation of new loading devices that can maintain viable IVD organ explants from large animals and human cadavers in precisely defined nutritional and mechanical environments over extended culture periods. Particularly in spine and IVD research, these organ culture models offer appealing alternatives, as large bipedal animal models with naturally occurring IVD degeneration and a genetic background similar to the human condition do not exist. Latest research has demonstrated important concepts including the potential of homing of mesenchymal stem cells to nutritionally or mechanically stressed IVDs, and the regenerative potential of "smart" biomaterials for nucleus pulposus or annulus fibrosus repair. In this review, we summarize the current knowledge about cell therapy, injection of cytokines and short peptides to rescue the degenerating IVD. We further stress that most bioreactor systems simplify the real in vivo conditions providing a useful proof of concept. Limitations are that certain aspects of the immune host response and pain assessments cannot be addressed with ex vivo systems. Coccygeal animal disc models are commonly used because of their availability and similarity to human IVDs. Although in vitro loading environments are not identical to the human in vivo situation, 3D ex vivo organ culture models of large animal coccygeal and human lumbar IVDs should be seen as valid alternatives for screening and feasibility testing to augment existing small animal, large animal, and human clinical trial experiments.

  14. A computational model for investigating the effects of changes in bioavailability of insulin-like growth factor-1 on the homeostasis of the intervertebral disc.

    Science.gov (United States)

    Elmasry, Shady; Asfour, Shihab; de Rivero Vaccari, Juan Pablo; Travascio, Francesco

    2016-11-01

    Insulin-like growth factor-1 (IGF-1) is well-known for upregulating cell proliferation and biosynthesis of the extracellular matrix in the intervertebral disc (IVD). Pathological conditions, such as obesity or chronic kidney disease cause IGF-1 deficiency in plasma. How this deficiency impacts disc homeostasis remains unknown. Pro-anabolic approaches for the treatment of disc degeneration based on enhancing IGF-1 bioavailability to tissue-cells are considered, but knowledge of their effectiveness in enhancing cellular anabolism of a degenerated disc is limited. In this study, we developed a computational model for disc homeostasis specifically addressing the role of IGF-1 in modulating both extracellular matrix biosynthesis and cellularity in the IVD. This model was applied to investigate how changes in IGF-1 bioavailability, namely deficiency or enhancement of growth factor, affect disc health. In this study, it was found that IGF-1 deficiency mainly affects the biosynthesis of ECM components, especially in the most external regions of the IVD such as the cartilage endplates and the outer portion of annulus fibrosus. Also, a total of three approaches for increasing IGF-1 bioavailability as a therapy for degenerated IVDs were investigated. It was found that all these strategies are only beneficial to those disc regions receiving sufficient nutritional supply (i.e., the outmost IVD regions), while they exacerbate tissue degradation in malnourished regions (i.e., inner portion of the disc). This suggests that pro-anabolic growth factor-based therapies are limited in that their success strongly depends on an adequate nutritional supply to the IVD tissue, which is not guaranteed in degenerated discs. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Axial T2* mapping in intervertebral discs: a new technique for assessment of intervertebral disc degeneration

    Energy Technology Data Exchange (ETDEWEB)

    Hoppe, Sven; Quirbach, Sebastian; Krause, Fabian G.; Benneker, Lorin M. [Inselspital, Berne University Hospital, Department of Orthopaedic Surgery, Berne (Switzerland); Mamisch, Tallal C. [Inselspital, Berne University Hospital, Department of Radiology, Berne (Switzerland); Werlen, Stefan [Clinic Sonnenhof, Department of Radiology, Berne (Switzerland)

    2012-09-15

    To demonstrate the potential benefits of biochemical axial T2* mapping of intervertebral discs (IVDs) regarding the detection and grading of early stages of degenerative disc disease using 1.5-Tesla magnetic resonance imaging (MRI) in a clinical setting. Ninety-three patients suffering from lumbar spine problems were examined using standard MRI protocols including an axial T2* mapping protocol. All discs were classified morphologically and grouped as ''healthy'' or ''abnormal''. Differences between groups were analysed regarding to the specific T2* pattern at different regions of interest (ROIs). Healthy intervertebral discs revealed a distinct cross-sectional T2* value profile: T2* values were significantly lower in the annulus fibrosus compared with the nucleus pulposus (P = 0.01). In abnormal IVDs, T2* values were significantly lower, especially towards the centre of the disc representing the expected decreased water content of the nucleus (P = 0.01). In herniated discs, ROIs within the nucleus pulposus and ROIs covering the annulus fibrosus showed decreased T2* values. Axial T2* mapping is effective to detect early stages of degenerative disc disease. There is a potential benefit of axial T2* mapping as a diagnostic tool, allowing the quantitative assessment of intervertebral disc degeneration. circle Axial T2* mapping effective in detecting early degenerative disc disease. (orig.)

  16. Biomechanical analysis of two-step traction therapy in the lumbar spine.

    Science.gov (United States)

    Park, Won Man; Kim, Kyungsoo; Kim, Yoon Hyuk

    2014-12-01

    Traction therapy is one of the most common conservative treatments for low back pain. However, the effects of traction therapy on lumbar spine biomechanics are not well known. We investigated biomechanical effects of two-step traction therapy, which consists of global axial traction and local decompression, on the lumbar spine using a validated three-dimensional finite element model of the lumbar spine. One-third of body weight was applied on the center of the L1 vertebra toward the superior direction for the first axial traction. Anterior translation of the L4 vertebra was considered as the second local decompression. The lordosis angle between the superior planes of the L1 vertebra and sacrum was 44.6° at baseline, 35.2° with global axial traction, and 46.4° with local decompression. The fibers of annulus fibrosus in the posterior region, and intertransverse and posterior longitudinal ligaments experienced stress primarily during global axial traction, these stresses decreased during local decompression. A combination of global axial traction and local decompression would be helpful for reducing tensile stress on the fibers of the annulus fibrosus and ligaments, and intradiscal pressure in traction therapy. This study could be used to develop a safer and more effective type of traction therapy.

  17. An Experimental Study of the Effects of Nicotine on the Intervertebral Disc

    Directory of Open Access Journals (Sweden)

    Nahla M. Afifi**# and Kawther A. Hafez

    2007-06-01

    Full Text Available Backgrounds: Clinically it had been noticed that a large proportion of patients presenting with low back pain are smokers. Therefore, in this experimental study the histological effects of nicotine on the lumbar intervertebral discs of the rabbits was investigated. Material and Methods: Eighteen rabbits were divided equally into 3 groups, Group 1 (a & b; as control. Group2 injected intraperitoneally by 5000 ng/kg nicotine daily for 4 weeks. Group3 injected intraperitoneally by 5000 ng/kg nicotine daily for 8 weeks. The selected dose produced blood nicotine levels equivalent to those found in heavy smokers (30 cigarettes / day. Results: Light and electron microscopic studies revealed that nicotine injection showed a variety of histological changes, which were not observed in the control group. This includes appearance of spaces within the nucleus pulposus and separation from the adjacent fibrous lamellae in the annulus fibrosus. Also loss of the regularity of the multilayered structure of the annulus fibrosus, and excessive inclusions associated with vacuoles which continue with the rough endoplasmic reticulum within the chondrocytes. Disc degeneration was more marked in rabbits injected with nicotine for 8 weeks (G3 than in those injected for 4 weeks (G2. Conclusion: It could be concluded that the disc degeneration is more common among smokers and is correlated with the duration of exposure to nicotine.

  18. 妇产科腹部手术切口脂肪液化36例诊治体会%Clinical analysis of 180 cases treatment of phimosis and redundant prepuce using cerclage with the annulus praeputialis of Shang Ring

    Institute of Scientific and Technical Information of China (English)

    凌媚

    2011-01-01

    目的 分析探讨妇产科腹部切口脂肪液化的原因和防治措施.方法 回顾性分析1999年1月~2009年12月该院妇产科的36例腹部切口脂肪液化的临床资料.结果 全组病例均采用积极治疗后36例患者中32例一期愈合,余4例二期愈合,病人切口均未发生感染.结论 妇产科腹部切口脂肪液化的原因与肥胖病人脂肪含量过高、术者手术技巧、高频电刀的使用及合并症密切相关.提高手术操作水平,纠正患者全身异常情况,早期发现并运用积极的防治措施处理腹部切口可以缩短切口愈合时间.%Aim To evaluate and study clinical therapeutic efficacy of treatment of phimosis and redundant prepuce using cerclage with the Shang Ring annulus praeputialis. Methods 300 cases of phimosis and redundant prepuce were admitted since 2003,85 cases of whom were phimosis and 215 cases redundant prepuce. 180 cases of them were treated with Shang Ring circumcision, 120 cases with traditional circumcision. Results The differences between the Shang Ring circumcision and the traditional circumcision in operative time,hemorrhagic amount and painful duration time of lavement were statistically significant ( P < 0.01 ). Postoperative bleeding, infection of wound, scar of penis,longer prepuce in the traditional circumcision were 4,10,9,3 cases respectively. Postoperative infection of wound,Postoperative bleeding in the Shang Ring circumcision were 2,1 cases respectively. No scar of penis or longer prepuce occured. Its difference had statistical significance (P < 0.05). An overall complication rate was 23.2%. The complication for the traditional circumcision was 21.6% ,while that for Shang Ring circumcision was 1.6%. There is obvious difference between the two groups (P < 0.01). The patients were followed up for 1 ~ 6 months. The result was satisfactory in all with fewer complications. Conclusion Treatment of phimosis and redundant prepuce using cerclage with the

  19. Heat transfer characteristics of the fluidized bed through the annulus

    Science.gov (United States)

    Shedid, Mohamed H.; Hassan, M. A. M.

    2016-09-01

    The annular fluidized bed can be regarded as a promising technique for waste heat recovery applications. This study investigates on the determination of steady state values of the average heat transfer on the surface of the inner tube under different operating conditions that include: (1) input heat flux ranging from 557 to 1671 W/m2, (2) superficial air velocity ranging between 0.12 and 0.36 m/s, (3) initial bed height ranging from 25 to 55 cm, (4) ratio of the inner to the outer diameters ranging from 1/6 to 1/2 and Kaolin particle diameters ranging between 282 and 550 µm. The average values of the heat transfer coefficient along the inner tube (consisting of the fluidized and free board sections) are also deduced. An empirical correlation for calculating the Nusselt number is obtained for the given parameters and ranges.

  20. Stresses and Strains in a Cold-Worked Annulus

    Science.gov (United States)

    1988-09-01

    Airways Limited Ansett Airlines of Australia, Library BHP, Melbourne Research Laboratories Hawker de Havilland Aust Pty Ltd, Victoria, Library Hawker de...Library Statutory and State Authorities and Industry Aero-Space Technologies Australia, Manager/Librarian (2 copies) Australian Airlines, Library Qantas ...DOWNGRADING DARL APPROVAL 12. SECDARY DISTRIBUTION (OF THIS DoCUmr) Approved for public release. OVERSEAS ?2KQUIRIES OUTSIDE STATED LIMITATIONS SHOULD BE

  1. Approximate furthest neighbor with application to annulus query

    DEFF Research Database (Denmark)

    Pagh, Rasmus; Silvestri, Francesco; Sivertsen, Johan von Tangen

    2016-01-01

    -dimensional Euclidean space. The method builds on the technique of Indyk (SODA 2003), storing random projections to provide sublinear query time for AFN. However, we introduce a different query algorithm, improving on Indyk׳s approximation factor and reducing the running time by a logarithmic factor. We also present...

  2. Regional variations in correlation between photopic negative response of focal electoretinograms and ganglion cell complex in glaucoma.

    Science.gov (United States)

    Machida, Shigeki; Kaneko, Muneyoshi; Kurosaka, Daijiro

    2015-04-01

    To determine regional variations in a structure-function relationship, we correlated the the photopic negative response (PhNR) of the focal electoretinogram (ERG) with the ganglion cell complex (GCC) thickness in different retinal regions in patients with open angle glaucoma (OAG). Fifty-one eyes of 51 OAG patients (OAG group) and 17 eyes of 17 normal volunteers (control group) were studied. The OAG patients had different degrees of glaucoma ranging from early to advanced stages. The focal ERGs were elicited by a white, 15° hemispherical stimulus placed superior or inferior to the fovea. Focal ERGs were also elicited by a half annulus placed superior or inferior to the macular region. The diameter of the inner border of the annulus was 15° and that of the outer border was 30°. The average GCC thickness in areas corresponding to the location of the stimuli was measured in SD-OCT images. The PhNR amplitude and PhNR/b-wave amplitude ratio were significantly correlated with the GCC thickness in the superior and inferior hemispherical areas (p correlated with the GCC thickness in the superior and inferior semi-annular areas (p < 0.05). There were significant differences in the slopes of the regression lines plotting the GCC thickness and the PhNR amplitude or the PhNR/b-wave amplitude ratio between the spherical and semi-annular areas (superior: p < 0.01, inferior: p < 0.0005). The thinning of the GCC affects the RGC function measured by the PhNR more strongly in the central retinal area than in the surrounding retinal areas.

  3. Structure-function relationships in soft tissue mechanics: Examining how the micro-scale architecture of biochemical constituents effects health

    Science.gov (United States)

    Schultz, David Sheldon

    Countless debilitating pathologies exhibit symptoms that result from altered mechanical behavior of soft tissue. Therefore, it is of clinical and economic importance to mechanically evaluate soft tissues and attribute degenerative changes to alterations in structural constituents. The studies presented here focus on the annulus fibrosus and the sclera. Failure in these tissues is common and catastrophic. The annulus fibrosus may fail, resulting in herniation and nerve impingement, or the disc may degenerate over time, resulting in reduced mobility and pain. Similarly, the sclera may degenerate over time with intraocular pressure spurring creep behavior that distends the eye beyond its ideal shape. This causes myopic vision and puts patients at risk of macular degeneration and retinal detachment. These two tissues share a common structural role as the outer wall of a pressure vessel. Also, they are made of strikingly similar constituents, primarily consisting of water, type I collagen, glycosaminoglycans and elastin. The microstructure of these tissues, however, is very different. The annulus fibrosus is representative of an anisotropic tissue. Its well-organized fibril structure was analyzed via polarization modulated second harmonic microscopy in order to characterize fibril architecture. Structurally relevant biochemical constituents were quantified with biochemical assays. Morphologically healthy annulus tended to have a more highly organized microstructure and tended to absorb more strain energy when subject to a tensile load cycle. Given the strong correlation between fibril organization and select mechanical properties, predictive models will likely benefit from a characterization of fibril continuity and orientation coherence. The sclera is representative of an isotropic tissue. Its less-organized fibril structure has evolved to sustain biaxial plane stress. In the sclera, collagen content and associated crosslinks were primary determinants of stiffness

  4. A novel membrane anchor for FtsZ is linked to cell wall hydrolysis in Caulobacter crescentus.

    Science.gov (United States)

    Meier, Elizabeth L; Razavi, Shiva; Inoue, Takanari; Goley, Erin D

    2016-07-01

    In most bacteria, the tubulin-like GTPase FtsZ forms an annulus at midcell (the Z-ring) which recruits the division machinery and regulates cell wall remodeling. Although both activities require membrane attachment of FtsZ, few membrane anchors have been characterized. FtsA is considered to be the primary membrane tether for FtsZ in bacteria, however in Caulobacter crescentus, FtsA arrives at midcell after stable Z-ring assembly and early FtsZ-directed cell wall synthesis. We hypothesized that additional proteins tether FtsZ to the membrane and demonstrate that in C. crescentus, FzlC is one such membrane anchor. FzlC associates with membranes directly in vivo and in vitro and recruits FtsZ to membranes in vitro. As for most known membrane anchors, the C-terminal peptide of FtsZ is required for its recruitment to membranes by FzlC in vitro and midcell recruitment of FzlC in cells. In vivo, overproduction of FzlC causes cytokinesis defects whereas deletion of fzlC causes synthetic defects with dipM, ftsE and amiC mutants, implicating FzlC in cell wall hydrolysis. Our characterization of FzlC as a novel membrane anchor for FtsZ expands our understanding of FtsZ regulators and establishes a role for membrane-anchored FtsZ in the regulation of cell wall hydrolysis.

  5. Proporção entre os segmentos do anel da valva tricúspide normal: um parâmetro para realização da anuloplastia valvar Proportion among the segments of the normal tricuspid valve annulus: parameter for valve annuloplasty

    Directory of Open Access Journals (Sweden)

    Fernando Antoniali

    2006-09-01

    Full Text Available OBJETIVO: Determinar a proporção existente entre os segmentos do anel da valva tricúspide normal em humanos. MÉTODO: Foram estudados 30 corações de cadáveres humanos não formolizados, com menos de 6h de período post-mortem, sem lesões congênitas ou adquiridas e com valvas tricúspides continentes. A continência valvar foi confirmada por injeção de água sob pressão no interior do ventrículo direito estando a valva pulmonar fechada. Fotos digitais da valva tricúspide com o anel valvar íntegro, e após secção e retificação, foram avaliadas por programa de computador. Compararam-se as medidas médias e as razões entre elas nas condições de anel íntegro e retificado. RESULTADOS: Com o anel valvar íntegro, os valores médios do perímetro, segmento septal e ântero-posterior foram 105mm (±12,7, 30,6mm (±3,7 e 74mm (±9,4, respectivamente. Com o anel valvar retificado, os valores médios foram 117,5mm (±13,3, 32mm (±3,7, 46,3mm (±8,3 e 39,1mm (±8,5, respectivamente para perímetro, segmento septal, anterior e posterior. As razões médias entre o segmento ântero-posterior e o septal foram 2,43 (±0,212 e 2,67 (±0,304, respectivamente, em anéis íntegros e retificados. Houve diferenças significantes nas medidas do perímetro (pOBJECTIVE: The purpose of this study was to determine the proportions among the segments of the human tricuspid valve annulus. METHODS: A descriptive autopsy study was made of 30 human hearts without fixation, within six hours of death, without congenital or acquired lesions and without tricuspid regurgitation. Tricuspid valve insufficiency was excluded by the infusion of pressurized water in the right ventricle with the pulmonary valve closed. Digital images of the tricuspid ring in its anatomical position and after flattening were analyzed by specific software. The mean measurements and ratios were compared in the two different situations. RESULTS: The mean measurements of the perimeter

  6. 应用商环治疗包茎和包皮过长180例临床分析%Clinical analysis of 180 cases treatment of phimosis and redundant prepuce using cerclage with the annulus praeputialis of Shang Ring

    Institute of Scientific and Technical Information of China (English)

    方志启; 吴刚; 王贺彬

    2011-01-01

    Aim To evaluate and study clinical therapeutic efficacy of treatment of phimosis and redundant prepuce using cerclage with the Shang Ring annulus praeputialis. Methods 300 cases of phimosis and redundant prepuce were admitted since 2003,85 cases of whom were phimosis and 215 cases redundant prepuce. 180 cases of them were treated with Shang Ring circumcision, 120 cases with traditional circumcision. Results The differences between the Shang Ring circumcision and the traditional circumcision in operative time,hemorrhagic amount and painful duration time of lavement were statistically significant ( P < 0.01 ). Postoperative bleeding, infection of wound, scar of penis,longer prepuce in the traditional circumcision were 4,10,9,3 cases respectively. Postoperative infection of wound,Postoperative bleeding in the Shang Ring circumcision were 2,1 cases respectively. No scar of penis or longer prepuce occured. Its difference had statistical significance (P < 0.05). An overall complication rate was 23.2%. The complication for the traditional circumcision was 21.6% ,while that for Shang Ring circumcision was 1.6%. There is obvious difference between the two groups (P < 0.01). The patients were followed up for 1 ~ 6 months. The result was satisfactory in all with fewer complications. Conclusion Treatment of phimosis and redundant prepuce using cerclage with the Shang Ring is believed to be the most ideal surgical operation.%目的 探讨和评价应用商环治疗包皮过长和包茎的方法和临床治疗效果.方法 自2003 年起,共收治包茎和包皮过长患者 300例,包茎 85例,包皮过长 215 例,行商环包皮环切术180例,传统术式包皮环切术120例.结果 商环术式手术时间、术中出血量、沐浴时间和术后创口疼痛时间与传统术式比较差异显著,均有统计学意义(P<0.01).传统术式发生出血4 例,伤口感染 10 例,术后疤痕 9例,包皮过长3 例;商环术式术后伤口感染 2

  7. Stem Cells

    Science.gov (United States)

    Stem cells are cells with the potential to develop into many different types of cells in the body. ... the body. There are two main types of stem cells: embryonic stem cells and adult stem cells. Stem ...

  8. Measuring isovolumic contraction peak velocity at the tricuspid annulus by Doppler tissue imaging to ;assess right heart function in patients with pulmonary hypertension%组织多普勒成像测量三尖瓣环等容收缩期峰值速度在评价肺高压患者右心功能中的应用

    Institute of Scientific and Technical Information of China (English)

    魏丽群; 李越; 王广义; 朱航; 王娟; 翟亚楠

    2014-01-01

    imaging. Methods In 41 patients with suspected diagnosis of PH, IVCv at the tricuspid annulus were measured by echocardiography and Doppler tissue imaging. The right heart systolic function parameters such as tricuspid annular plane systolic excursion (TAPSE), peak systolic velocity (PSv) and right ventricular fractional area change (RVFCA) were also measured. The pulmonary artery pressure was detected by right-heart catheterization (RHC). According to different levels of pulmonary arterial systolic pressure, patients were classiifed into four groups to compare and analyze if any signiifcance could be found, including without PH group, mild PH group, moderate PH group and severe PH group. The sensitivity and speciifcity for diagnosing right heart impairment were assessed by ROC curves. Last, correlation analysis was performed. Results IVCv was signiifcantly and positively correlated with the right heart systolic function parameters, such as TAPSE (r=0.557, P0.05). Using the lower limit of right ventricular systolic function parameter obtained by common echocardiographic assessment as standard (TAPSE<16 mm, PSv<10 cm/s and RVFAC<35%), the sensitivities of IVCv<6.5 cm/s for diagnosing right ventricular systolic function reduction were 91%, 96%and 87%and the speciifcities were 70%, 53%and 77%, respectively. Conclusions IVCv obtained by Doppler tissue imaging is a new objective parameter for diagnosing right ventricular systolic function reduction. It is worth further study and application in clinic.

  9. Plastia tricúspide utilizando anuloplastia baseada na proporção entre os segmentos do anel da valva tricúspide normal Tricuspid valve repair using the proportion between segments of normal tricuspid annulus as a parameter for annuloplasty

    Directory of Open Access Journals (Sweden)

    Fernando Antoniali

    2007-12-01

    Full Text Available OBJETIVO: Determinar a proporção existente entre os segmentos do anel da valva tricúspide (VT normal e aplicála na realização da anuloplastia tricúspidea "in vitro" e "in vivo". MÉTODOS: Imagens digitais do anel tricuspídeo de 30 corações de cadáveres humanos, sem formolização e sem insuficiência tricúspide (IT, foram analisadas e a proporção entre os segmentos ântero-posterior e septal foi determinada. Esta proporção foi utilizada na anuloplastia da VT com anel maleável de pericárdio bovino (PB, em 15 corações de cadáveres com IT e dilatação do anel valvar. A mesma proporção e técnica foi utilizada na realização de anuloplastia tricuspídea, em 11 pacientes com IT funcional, entre os quais, sete possuíam IT importante e quatro, moderada; cinco apresentavam insuficiência cardíaca (IC classe IV (NYHA e seis, classe III. RESULTADOS: Nas valvas continentes de cadáveres, a razão média entre o segmento ântero-posterior e septal foi 2,43±0,212. O tamanho médio dos anéis maleáveis PB utilizados "in vitro" foi 71,5±5,2mm e mediana 70mm. Todas as valvas ficaram continentes após a anuloplastia tricuspídea "in vitro". O tamanho médio do anel maleável PB utilizado "in vivo" foi 73,4±6,5mm e mediana 72mm. Ocorreu um (9,1% óbito. Na avaliação com 6 meses de pós-operatório, sete pacientes não possuíam IT e três possuíam IT leve; seis pacientes apresentavam IC classe I, três, classe II e um, classe III. CONCLUSÃO: O uso da proporção de 2,43:1 entre os segmentos ântero-posterior e septal, como um parâmetro na anuloplastia da VT, utilizando anel maleável de pericárdio bovino, demonstrou resultados iniciais favoráveis.OBJECTIVE: To determine the proportion between the segments of the normal human tricuspid valve (TV annulus and its use as a parameter for ring annuloplasty "in vitro" and "in vivo". METHODS: Digital images of the tricuspid ring of 30 human cadaveric hearts, without fixation and

  10. Cells, cells, and more cells.

    Science.gov (United States)

    Bhatti, M Tariq; Gres, Katherine E; Petitto, Virginia B; Cross, Shelley Ann

    2007-01-01

    A 64-year-old woman presented with bilateral optic nerve swelling, vitreous cells, and cerebrospinal fluid monocytic pleocytosis. A chest radiograph and computed tomography demonstrated a lesion in the left lung, which histologically was confirmed to be a small-cell lung carcinoma. The serum was positive for the anti-CV2 (anti-CRMP-5) antibody. Following treatment with chemoradiation the optic nerve swelling and vitritis resolved. The differential diagnosis of uveal-meningeal diseases is discussed and the pathophysiology and clinical manifestations of paraneoplastic syndromes reviewed.

  11. Effect of siRNA interference on nerve growth factor in intervertebral disc inflammation rats

    Institute of Scientific and Technical Information of China (English)

    Ming-Lei Lang; Ai-Lin Qin; Jian-Min Li; Peng Fu

    2014-01-01

    Objective:To investigate the inhibition effect of siRNA interference onNGF induced by inflammatory factorIL-6, andIL-1 so as to provide novel targets for clinical treatment of discogenic low back pain.Methods:The intervertebral disc nucleus and annulus fibrosus cells of rats were separated .The cells were co-cultured with different concentrations(10 nmol/L,20 nmol/L,50 nmol/L,100 nmol/L) ofIL-6 andIL-1β.TheNGF- siRNA was leaded into the co-cultured cells with its import ability assessed by flow cytometry instrument tests,before and after which theNGF mRNA expression was detected by real-timeQ-PCR and theNGF content was detected byELISA.Results:Flow cytometry instrument test results showed that theNGF-siRNA cell conversion rate was99.8%.Real-timeQ-PCR detection results showed that compared with negative control group, theNGF mRNA expression of co-cultured cells treated by10 nmol/L,20 nmol/L,50 nmol/L,100 nmol/LIL-6 andIL-1β were respectively raised3.4,3.7,4.7, 3.7 times which were all significantly down-regulated after the import ofNGF- siRNA.EILSA detection results showed that compared with negative control group, theNGF content of co-cultured medium treated by10 nmol/L,20 nmol/L,50 nmol/L,100 nmol/LI-L6 andIL-1β were respectively raised2.9,3.3,4.5,7.4 times which were all significantly decreased after the import ofNGF- siRNA.Conclusions:These molecular biological results suggest that inflammatory factorIL-6 andIL-1β could stimulateNGF on intervertebral disc cells in vitro culture model and its efficiency is concentration dependent, while siRNA interference can inhibit the stimulation effect ofIL-6 andIL-1β on intervertebral disc cell, which provides a new targets for the clinical treatment of discogenic low back pain.

  12. Primary Intimal (Spindle Cell Sarcoma of the Heart: A Case Report and Review of the Literature

    Directory of Open Access Journals (Sweden)

    A. Ibrahim

    2013-01-01

    Full Text Available Intimal (spindle cell sarcomas of the left atrium are extremely rare primary cardiac tumours with three cases reported (Li et al. (2013, Cho et al. (2006, and Modi et al. (2009. We present a 69-year-old man who first came to medical attention after experiencing abdominal discomfort. He had a 30 lb weight loss apparently due to dieting. He denied any other constitutional symptoms. His symptoms persisted despite a course of antibiotics for presumed diverticulitis. Laboratory values were within normal limits, though the haemoglobin was 131 g/L (normal: 140–180. Subsequent abdominal computed tomography (CT scan revealed an abdominal wall mass and intracardiac lesion; the cardiac mass was further characterized by transesophageal echo (TEE, magnetic resonance imaging (MRI, and dedicated cardiac CT. TEE revealed a mass attached to the posterolateral wall of the left atrium above the mitral annulus, and the cardiac CT and MRI confirmed the TEE findings. The patient underwent extensive surgical resection and repair of the left side of the heart. Postoperatively, he developed acute renal failure requiring dialysis and reintubation for volume overload. He became acutely hypotensive, developed multiorgan failure, and succumbed to his illness. Histopathologic examination of the left atrial mass showed an intimal sarcoma.

  13. Diagnostics and therapy of spinal disc herniation; Diagnostik und Therapie des Bandscheibenvorfalls

    Energy Technology Data Exchange (ETDEWEB)

    Zimmer, A.; Reith, W. [Universitaetsklinikum des Saarlandes, Klinik fuer Diagnostische und Interventionelle Neuroradiologie, Homburg/Saar (Germany)

    2014-11-15

    Degenerative processes in a movement segment of the vertebral column, which can potentially give rise to herniation of elements of the nucleus pulposus, are complex and of variable clinical and radiological dimensions; however the mere assumption that degenerative changes precede disc herniation remains a matter of debate. By definition, spinal disc herniation (SDH) refers to components of the gelatinous nucleus pulposus protruding beyond the dorsal level of the vertebral body margin through tears in the annulus fibrosus. Clinical presentation may include pain, paresis and sensory disturbances. Magnetic resonance imaging (MRI) is considered the gold standard in the diagnosis of SDH. In the majority of patients a conservative approach with physical therapy exercises and adequate analgesic and antiphlogistic medical treatment results in a substantial improvement of symptoms. (orig.) [German] Degenerative Prozesse eines Bewegungssegments, die in einem Prolaps des Nucleus pulposus resultieren koennen, sind vielschichtig und von unterschiedlicher klinischer und radiologischer Auspraegung. Selbst die Annahme, dass Bandscheibenvorfaellen eine Degeneration vorangeht, ist keineswegs unumstritten. Definitionsgemaess spricht man von einem Bandscheibenvorfall (BSV), wenn das Gewebe des gelatinoesen Nucleus pulposus durch eine Dehiszenz im Anulus fibrosus ueber das Niveau der normalen dorsalen Begrenzung des Bandscheibenfachs hinaus prolabiert. Klinisch kann dies mit Schmerzen, Paresen und Sensibilitaetsstoerungen einhergehen. Die Magnetresonanztomographie gilt als Goldstandard in der Diagnostik eines BSV. In der Mehrzahl der Faelle fuehrt ein konservatives Vorgehen zu einer deutlichen Besserung der Symptomatik im Verlauf. (orig.)

  14. Dendritic Cell

    OpenAIRE

    Sevda Söker

    2005-01-01

    Dendritic cells, a member of family of antigen presenting cells, are most effective cells in the primary immune response. Dendritic cells originated from dendron, in mean of tree in the Greek, because of their long and elaborate cytoplasmic branching processes. Dendritic cells constitute approximately 0.1 to 1 percent of the blood’s mononuclear cell. Dendritic cells are widely distributed, and specialized for antigen capture and T cell stimulation. In this article, structures and functions of...

  15. Spondarthritis in the triassic.

    Directory of Open Access Journals (Sweden)

    Juan Carlos Cisneros

    Full Text Available BACKGROUND: The evidence of several forms of arthritis has been well documented in the fossil record. However, for pre-Cenozoic vertebrates, especially regarding reptiles, this record is rather scarce. In this work we present a case report of spondarthritis found in a vertebral series that belonged to a carnivorous archosaurian reptile from the Lower Triassic (∼245 million years old of the South African Karoo. METHODOLOGY/PRINCIPAL FINDINGS: Neutron tomography confirmed macroscopic data, revealing the ossification of the entire intervertebral disc space (both annulus fibrosus and nucleus pulposus, which supports the diagnosis of spondarthritis. CONCLUSIONS/SIGNIFICANCE: The presence of spondarthritis in the new specimen represents by far the earliest evidence of any form of arthritis in the fossil record. The present find is nearly 100 million years older than the previous oldest report of this pathology, based on a Late Jurassic dinosaur. Spondarthritis may have indirectly contributed to the death of the animal under study.

  16. A bimodular theory for finite deformations: Comparison of orthotropic second-order and exponential stress constitutive equations for articular cartilage.

    Science.gov (United States)

    Klisch, Stephen M

    2006-06-01

    Cartilaginous tissues, such as articular cartilage and the annulus fibrosus, exhibit orthotropic behavior with highly asymmetric tensile-compressive responses. Due to this complex behavior, it is difficult to develop accurate stress constitutive equations that are valid for finite deformations. Therefore, we have developed a bimodular theory for finite deformations of elastic materials that allows the mechanical properties of the tissue to differ in tension and compression. In this paper, we derive an orthotropic stress constitutive equation that is second-order in terms of the Biot strain tensor as an alternative to traditional exponential type equations. Several reduced forms of the bimodular second-order equation, with six to nine parameters, and a bimodular exponential equation, with seven parameters, were fit to an experimental dataset that captures the highly asymmetric and orthotropic mechanical response of cartilage. The results suggest that the bimodular second-order models may be appealing for some applications with cartilaginous tissues.

  17. Acute pyogenic discitis in a degenerative intervertebral disc in an adult

    Directory of Open Access Journals (Sweden)

    Masamitsu Tanaka

    2010-08-01

    Full Text Available Masamitsu Tanaka1,2, Hiroshi Shimizu2, Yoshiyuki Yato1, Takashi Asazuma1, Koichi Nemoto11Department of Orthopedic Surgery, National Defense Medical College, Tokorozawa, Saitama; 2Department of Orthopedic Surgery, Self Defense Force Fukuoka Hospital, Kasuga, Fukuoka, JapanAbstract: A 35-year-old male who had been receiving conservative treatment for L4 isthmic spondylolisthesis suffered from pyogenic spondylodiscitis in the degenerative L4/L5 intervertebral disc space, which could be identified by comparison with previous images. Symptoms improved with conservative antibiotic treatment. Neovascularization may occur in the annulus fibrosus of a degenerative intervertebral disc, which may increase the risk of hematogenous infection, leading to “discitis” even in adults.Keywords: spondylodiscitis, spondylitis, discitis, isthmic spondylolisthesis, spondylolysis, intervertebral disc degeneration

  18. Spondarthritis in the Triassic

    Science.gov (United States)

    Cisneros, Juan Carlos; Gomes Cabral, Uiara; de Beer, Frikkie; Damiani, Ross; Costa Fortier, Daniel

    2010-01-01

    Background The evidence of several forms of arthritis has been well documented in the fossil record. However, for pre-Cenozoic vertebrates, especially regarding reptiles, this record is rather scarce. In this work we present a case report of spondarthritis found in a vertebral series that belonged to a carnivorous archosaurian reptile from the Lower Triassic (∼245 million years old) of the South African Karoo. Methodology/Principal Findings Neutron tomography confirmed macroscopic data, revealing the ossification of the entire intervertebral disc space (both annulus fibrosus and nucleus pulposus), which supports the diagnosis of spondarthritis. Conclusions/Significance The presence of spondarthritis in the new specimen represents by far the earliest evidence of any form of arthritis in the fossil record. The present find is nearly 100 million years older than the previous oldest report of this pathology, based on a Late Jurassic dinosaur. Spondarthritis may have indirectly contributed to the death of the animal under study. PMID:20976231

  19. Fibre orientation contrast for depth-resolved identification of structural interfaces in birefringent tissue

    Energy Technology Data Exchange (ETDEWEB)

    Kemp, Nate J; Park, Jesung; Zaatari, Haitham N; III, H Grady Rylander; Milner, Thomas E [Department of Biomedical Engineering, University of Texas at Austin, 1 University Station C0800, Austin, TX 78712-1084 (United States)

    2006-08-07

    Incorporation of polarimetric sensitivity into optical coherence tomography can provide additional image contrast when structures of interest are optically anisotropic (e.g., fibrous tissue). We present a generalized technique based on polarization-sensitive optical coherence tomography to detect changes in depth-resolved fibre orientation and thus increase image contrast in multiple-layered birefringent tissues. A high contrast B-scan image of collagen fibre orientation is shown for a porcine intervertebral disc cartilage specimen that exhibited low backscattering intensity contrast. Interfaces in the annulus fibrosus identified using depth-resolved fibre orientation allowed quantification of lamellae thickness. Moreover, the technique detects changes in fibre orientation without intense processing needed to effectively quantify tissue retardation and diattenuation.

  20. The effect of posterior spinal fixation with acrylic cement on the vertebral growth plate and intervertebral disc in dogs.

    Science.gov (United States)

    Moon, M S; Ok, I Y; Ha, K Y

    1986-01-01

    We have attempted to clarify the serial histological changes in the growing spine of dogs following posterior fixation with acrylic cement. Twenty-four male mongrel dogs aged 8 weeks were used for the study. The lumbar spine from L.3 to L.5 was fixed posteriorly with acrylic cement. Three dogs were then sacrificed every four weeks up to 32 weeks, and the histological changes of the vertebral disc, growth plate and vertebral bodies were observed by light microscopy. Thinning of the growth plate and distortion of the cartilage columns has been demonstrated, but premature fusion of the growth plate did not result and vertebral body growth continued. Anterior wedging of the intervertebral disc was seen with some thinning of the bony trabeculae of the vertebral body. Degeneration of the nucleus pulposus resulted, with replacement by fibrous tissue. The normal horizontal arrangement of the fibres of the annulus fibrosus altered to a vertical configuration by 32 weeks.

  1. Novel rat tail discitis model using bioluminescent Staphylococcus aureus.

    Science.gov (United States)

    Bostian, Phillip A; Karnes, Jonathan M; Cui, Shari; Robinson, Lisa J; Daffner, Scott D; Witt, Michelle R; Emery, Sanford E

    2017-09-01

    Management of spondylodiscitis is a challenging clinical problem requiring medical and surgical treatment strategies. The purpose of this study was to establish a rat model of spondylodiscitis that utilizes bioluminescent Staphylococcus aureus (S. aureus), thus permitting in vivo surveillance of infection intensity. Inocula of the bioluminescent S. aureus strain XEN36 were created in concentrations of 10(2) CFU/0.1 ml, 10(4)  CFU/0.1 ml, and 10(6)  CFU/0.1 ml. Three groups of rats were injected with the bacteria in the most proximal intervertebral tail segment. The third most proximal tail segment was injected with saline as a control. Bioluminescence was measured at baseline, 3 days, and weekly for a total of 6 weeks. Detected bioluminescence for each group peaked at day 3 and returned to baseline in 21 days. The average intensity was highest for the experimental group injected with the most concentrated bacterial solution (10(6)  CFU/0.1 ml). Radiographic analysis revealed loss of intervertebral disc space and evidence of osseous bridging. Saline-injected spaces exhibited no decrease in intervertebral spacing as compared to distal sites. Histologic analysis revealed neutrophilic infiltrates, destruction of the annulus fibrosus and nucleus pulposus, destruction of vertebral endplates, and osseous bridging. Saline-injected discs exhibited preserved annulus fibrosus and nucleus pulposus on histology. This study demonstrates that injection of bioluminescent S. aureus into the intervertebral disc of a rat tail is a viable animal model for spondylodiscitis research. This model allows for real-time, in vivo quantification of infection intensity, which may decrease the number of animals required for infection studies of the intervertebral disc. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2075-2081, 2017. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

  2. The influence of the intervertebral disc on stress distribution of the thoracolumbar vertebrae under destructive load

    Institute of Scientific and Technical Information of China (English)

    刘雷; 裴福兴; 宋跃明; 邹力; 张聪; 周宗科

    2002-01-01

    Objective: To compare the influence of normal and degenerative discs on stress distribution of the thoracolumbar vertebrae under destructive load, explore the biomechanical background and clinical meaning and provide theoretical basis for clinical diagnosis and treatment.Methods: A mechanical model of thoracolumbar motion segment of normal and degenerative discs was built with a three dimensional finite element method and three stresses of vertical compression, compressive flexion and distractive flexion were comparatively analyzed.Results: With vertical compression and compressive flexion loads, the thoracolumbar motion segment of the normal disc showed that the central part of the upper and lower end-plates of the vertebrae and the central part of the trabecular bone adjacent to the end-plate were loaded with the most intensive stresses, meanwhile, the postero-lateral part of the annulus fibrosus was concentrated with stresses. Degenerative disc showed that the stress distribution of the trabecular bone was relatively averaged, the stresses of the central part adjacent to the end-plate were low, while at the same time, the stresses of the peripheral part were elevated relatively. With distraction flexion load, the stresses of the cortex bone, trabecular bone, end-plate and annulus fibrosus of the thoracolumbar vertebrae of degenerative discs were low, meanwhile, the stresses of the posterior structure of the vertebral body were relatively elevated compared with that of normal discs.Conclusions: There is difference in influence between normal and degenerative discs on the stress distribution of the thoracolumbar vertebrae with destructive load. The transferring way of load is changed after disc degeneration.

  3. The influence of the interertebral disc on stress distribution of the thoracolumbar vertebrae under destructive load

    Institute of Scientific and Technical Information of China (English)

    刘雷; 裴福兴; 等

    2002-01-01

    Objectie:To compare the influence of normal and degenerative discs on stress distribution of the thoracolumbar vertebrae under destructive load,explore the biomechanical background and clinical meaning and provide theoretical basis for clinical diagnosis and treatment.Methods:A mechanical model of thoracolumbar motion segment of normal and degenerative discs was built with a three dimensional finite element method and three stresses of vertical compression,compressive flexion and distractive flexion were comparatively analyzed.Results:With vertical compression and compressive flexion loads,the thoracolumbar motion segment of the normal disc showed that the central part of the upper and lower end-plates of the vertebrae and the central part of the trabecular bone adjacent to the end-plate were lgaded with the most intensive stresses,meanwhile,the postero-lateral part of the annulus fibrosus was concentrated with stresses.Degeneratie disc showed that the stress distribution of the trabecular bone was relatively averaged,the stresses of the central part adjacent to the end-plate were low,while at the same time,the stresses of the peripheral part were elevated relatively.With distraction flexion load,the stresses of the cortex bone,trabecular bone,end-plate and annulus fibrosus of the thoracolumbar vertebrae of degenerative discs were low,neanwhile,the stresses of the posterior structure of the vertebral body were relatively elevated compared with that of normal discs.Conclusions:There is difference in influence between normal and degen erative discs on the stress distribution of the thoracolumbar vertebrae with destructive load.The transferring way of load is changed after disc degeneration.

  4. Galvanic Cells

    Science.gov (United States)

    Young, I. G.

    1973-01-01

    Many standard physical chemistry textbooks contain ambiguities which lead to confusion about standard electrode potentials, calculating cell voltages, and writing reactions for galvanic cells. This article shows how standard electrode potentials can be used to calculate cell voltages and deduce cell reactions. (Author/RH)

  5. Galvanic Cells

    Science.gov (United States)

    Young, I. G.

    1973-01-01

    Many standard physical chemistry textbooks contain ambiguities which lead to confusion about standard electrode potentials, calculating cell voltages, and writing reactions for galvanic cells. This article shows how standard electrode potentials can be used to calculate cell voltages and deduce cell reactions. (Author/RH)

  6. Cell Biochips

    Science.gov (United States)

    Pioufle, B. Le; Picollet-D'Hahan, N.

    A cell biochip is a microsystem, equipped with electronic and microfluidic functions, designed to manipulate or analyse living cells. The first publications in this emerging area of research appeared toward the end of the 1980s. In 1989 Washizu described a biochip designed to fuse two cells by electropermeabilisation of the cytoplasmic membrane [1]. Research centers have devised a whole range of cell chip structures, for simultaneous or sequential analysis of single cells, cell groups, or cell tissues reconstituted on the chip. The cells are arranged in a square array on a parallel cell chip for parallel analysis, while they are examined and processed one by one in a microchannel in the case of a series cell chip. In contrast to these biochips for high-throughput analysis of a large number of cells, single-cell chips focus on the analysis of a single isolated cell. As in DNA microarrays, where a large number of oligonucleotides are ordered in a matrix array, parallel cell chips order living cells in a similar way. At each point of the array, the cells can be isolated, provided that the cell type allows this, e.g., blood cells, or cultivated in groups (most adhesion cells can only survive in groups). The aim is to allow massively parallel analysis or processing. Le Pioufle et al. describe a microdevice for the culture of single cells or small groups of cells in a micropit array [2]. Each pit is equipped to stimulate the cell or group of cells either electrically or fluidically. Among the applications envisaged are gene transfer, cell sorting, and screening in pharmacology. A complementary approach, combining the DNA microarray and cell biochip ideas, has been put forward by Bailey et al. [3]. Genes previously arrayed on the chip transfect the cultured cells on the substrate depending on their position in the array (see Fig. 19.1). This way of achieving differential lipofection on a chip was then taken up again by Yoshikawa et al. [4] with primary cells, more

  7. Molecular characterization of retinal stem cells and their niches in adult zebrafish

    Directory of Open Access Journals (Sweden)

    Barthel Linda K

    2006-07-01

    Full Text Available Abstract Background The persistence in adult teleost fish of retinal stem cells that exhibit all of the features of true 'adult stem cells' – self-renewal, multipotency, and the capacity to respond to injury by mitotic activation with the ability to regenerate differentiated tissues – has been known for several decades. However, the specialized cellular and molecular characteristics of these adult retinal stem cells and the microenvironmental niches that support their maintenance in the differentiated retina and regulate their activity during growth and regeneration have not yet been elucidated. Results Our data show that the zebrafish retina has two kinds of specialized niches that sustain retinal stem cells: 1 a neuroepithelial germinal zone at the interface between neural retina and ciliary epithelium, called the ciliary marginal zone (CMZ, a continuous annulus around the retinal circumference, and 2 the microenvironment around some Müller glia in the differentiated retina. In the uninjured retina, scattered Müller glia (more frequently those in peripheral retina are associated with clusters of proliferating retinal progenitors that are restricted to the rod photoreceptor lineage, but following injury, the Müller-associated retinal progenitors can function as multipotent retinal stem cells to regenerate other types of retinal neurons. The CMZ has several features in common with the neurogenic niches in the adult mammalian brain, including access to the apical epithelial surface and a close association with blood vessels. Müller glia in the teleost retina have a complex response to local injury that includes some features of reactive gliosis (up-regulation of glial fibrillary acidic protein, GFAP, and re-entry into the cell cycle together with dedifferentiation and re-acquisition of phenotypic and molecular characteristics of multipotent retinal progenitors in the CMZ (diffuse distribution of N-cadherin, activation of Notch

  8. Annulus Enlargement in Aortic Valve Replacement of Small Aortic Annulus%小主动脉瓣环患者主动脉瓣置换术41例

    Institute of Scientific and Technical Information of China (English)

    王红兵; 周更须; 郑奇军; 陈文生; 蔡振杰; 刘维永

    2006-01-01

    目的总结主动脉瓣环加宽后的主动脉瓣置换术治疗小主动脉瓣环合并主动脉瓣病变患者的临床经验.方法对41例小主动脉瓣环合并主动脉瓣病变患者(瓣环直径为15~21 mm)行主动脉瓣环加宽后的主动脉瓣置换术,主动脉瓣环加宽采用改良Nicks法11例,改良Manougnian法29例,Konno法1例.结果 41例患者主动脉瓣环加宽后都可以植入比测量的主动脉瓣环直径大1#或2#的主动脉瓣,无手术死亡.术后所有患者随访4~36个月(13±2个月),无死亡、瓣周漏、二尖瓣反流和主动脉扩张;超声心动图检查示:人工瓣跨瓣峰值压差为9~25mmHg(17±6mmHg),与术前的70~105mmHg(80±15mmHg)比较差别有统计学意义(P<0.01).结论小主动脉瓣环合并主动脉瓣病变患者,在置换主动脉瓣时先行主动脉瓣环加宽,能使患者在术后获得良好的血流动力学效果,是一种安全、有效的手术术式.

  9. Engineering cell-cell signaling.

    Science.gov (United States)

    Blagovic, Katarina; Gong, Emily S; Milano, Daniel F; Natividad, Robert J; Asthagiri, Anand R

    2013-10-01

    Juxtacrine cell-cell signaling mediated by the direct interaction of adjoining mammalian cells is arguably the mode of cell communication that is most recalcitrant to engineering. Overcoming this challenge is crucial for progress in biomedical applications, such as tissue engineering, regenerative medicine, immune system engineering and therapeutic design. Here, we describe the significant advances that have been made in developing synthetic platforms (materials and devices) and synthetic cells (cell surface engineering and synthetic gene circuits) to modulate juxtacrine cell-cell signaling. In addition, significant progress has been made in elucidating design rules and strategies to modulate juxtacrine signaling on the basis of quantitative, engineering analysis of the mechanical and regulatory role of juxtacrine signals in the context of other cues and physical constraints in the microenvironment. These advances in engineering juxtacrine signaling lay a strong foundation for an integrative approach to utilize synthetic cells, advanced 'chassis' and predictive modeling to engineer the form and function of living tissues.

  10. Stem cells in cell transplantation.

    Science.gov (United States)

    Sanmartin, Agneta; English, Denis; Sanberg, Paul R

    2006-12-01

    This commentary documents the increased number of stem cell-related research reports recently published in the cell transplantation field in the journal Cell Transplantation. The journal covers a wide range of issues in cell-based therapy and regenerative medicine and is attracting clinical and preclinical articles from around the world. It thereby complements and extends the basic coverage of stem cell physiology reported in Stem Cells and Development. Sections in Cell Transplantation cover neuroscience, diabetes, hepatocytes, bone, muscle, cartilage, skin, vessels, and other tissues, as well as tissue engineering that employs novel methods with stem cells. Clearly, the continued use of biomedical engineering will depend heavily on stem cells, and these two journals are well positioned to provide comprehensive coverage of these developments.

  11. Engineering Cell-Cell Signaling

    Science.gov (United States)

    Milano, Daniel F.; Natividad, Robert J.; Asthagiri, Anand R.

    2014-01-01

    Juxtacrine cell-cell signaling mediated by the direct interaction of adjoining mammalian cells is arguably the mode of cell communication that is most recalcitrant to engineering. Overcoming this challenge is crucial for progress in biomedical applications, such as tissue engineering, regenerative medicine, immune system engineering and therapeutic design. Here, we describe the significant advances that have been made in developing synthetic platforms (materials and devices) and synthetic cells (cell surface engineering and synthetic gene circuits) to modulate juxtacrine cell-cell signaling. In addition, significant progress has been made in elucidating design rules and strategies to modulate juxtacrine signaling based on quantitative, engineering analysis of the mechanical and regulatory role of juxtacrine signals in the context of other cues and physical constraints in the microenvironment. These advances in engineering juxtacrine signaling lay a strong foundation for an integrative approach to utilizing synthetic cells, advanced ‘chassis’ and predictive modeling to engineer the form and function of living tissues. PMID:23856592

  12. Cell Motility

    CERN Document Server

    Lenz, Peter

    2008-01-01

    Cell motility is a fascinating example of cell behavior which is fundamentally important to a number of biological and pathological processes. It is based on a complex self-organized mechano-chemical machine consisting of cytoskeletal filaments and molecular motors. In general, the cytoskeleton is responsible for the movement of the entire cell and for movements within the cell. The main challenge in the field of cell motility is to develop a complete physical description on how and why cells move. For this purpose new ways of modeling the properties of biological cells have to be found. This long term goal can only be achieved if new experimental techniques are developed to extract physical information from these living systems and if theoretical models are found which bridge the gap between molecular and mesoscopic length scales. Cell Motility gives an authoritative overview of the fundamental biological facts, theoretical models, and current experimental developments in this fascinating area.

  13. Photovoltaic Cells

    Directory of Open Access Journals (Sweden)

    Karolis Kiela

    2012-04-01

    Full Text Available The article deals with an overview of photovoltaic cells that are currently manufactured and those being developed, including one or several p-n junction, organic and dye-sensitized cells using quantum dots. The paper describes the advantages and disadvantages of various photovoltaic cells, identifies the main parameters, explains the main reasons for the losses that may occur in photovoltaic cells and looks at the ways to minimize them.Article in Lithuanian

  14. Ventricular structure and function in children with sickle cell disease using conventional and tissue Doppler echocardiography.

    Science.gov (United States)

    Eddine, Ahmad Charaf; Alvarez, Ofelia; Lipshultz, Steven E; Kardon, Richard; Arheart, Kristopher; Swaminathan, Sethuraman

    2012-05-01

    Conventional 2-dimensional, M-mode, and spectral Doppler echocardiographic techniques have documented abnormal ventricular function in adults with sickle cell disease (SCD), but assessments in children are conflicting. Tissue Doppler echocardiography (TDE) provides additional information about myocardial function. Two-dimensional, M-mode, tricuspid regurgitation jet velocity (TRJV) data, and tissue Doppler echocardiographically derived myocardial velocity measurements of left ventricular (LV) and right ventricular function were taken from children with SCD compared to those of similar healthy historical controls and correlated with clinical characteristics and hemoglobin levels. Compared to 55 controls, 54 children with SCD (mean age 14.2 years, range 6 to 21) had a larger left ventricle, greater LV mass, and higher LV fractional shortening; 30% had increased pulmonary artery pressure (TRJV ≥2.5 m/s). Conventional echocardiographic measurements of LV systolic function and spectral Doppler measurements of LV and right ventricular diastolic function were essentially normal, but TDE indicated that 31% of SCD children had evidence of LV diastolic dysfunction (peak early diastolic velocity of LV inflow Doppler/peak early diastolic velocity at lateral mitral valve annulus >8), a finding that correlated with lower hemoglobin levels. Although decreasing hemoglobin levels in children with SCD correlated with LV hypertrophy, LV dilation, and LV diastolic dysfunction, long-term transfusion or hydroxyurea therapy did not affect these measurements. In conclusion, 1/3 of children with SCD had tissue Doppler echocardiographic evidence of LV diastolic dysfunction, which was correlated with hemoglobin levels. Adding serial assessments of ventricular function with TDE to conventional echocardiography may detect early cardiac changes, especially in children with severe anemia.

  15. Engineering Cell-Cell Signaling

    OpenAIRE

    Blagovic, Katarina; Gong, Emily S.; Milano, Daniel F.; Natividad, Robert J.; Asthagiri, Anand R

    2013-01-01

    Juxtacrine cell-cell signaling mediated by the direct interaction of adjoining mammalian cells is arguably the mode of cell communication that is most recalcitrant to engineering. Overcoming this challenge is crucial for progress in biomedical applications, such as tissue engineering, regenerative medicine, immune system engineering and therapeutic design. Here, we describe the significant advances that have been made in developing synthetic platforms (materials and devices) and synthetic cel...

  16. Quantitative in vivo MRI evaluation of lumbar facet joints and intervertebral discs using axial T2 mapping

    Energy Technology Data Exchange (ETDEWEB)

    Stelzeneder, David; Messner, Alina; Scheurecker, Georg; Goed, Sabine; Friedrich, Klaus M.; Trattnig, Siegfried [Medical University of Vienna, Department of Radiology, MR Centre-High Field MR, Vienna (Austria); Vlychou, Marianna [Medical University of Vienna, Department of Radiology, MR Centre-High Field MR, Vienna (Austria); University Hospital of Larissa, Department of Radiology, Larissa (Greece); Welsch, Goetz H. [Medical University of Vienna, Department of Radiology, MR Centre-High Field MR, Vienna (Austria); University of Erlangen, Department of Trauma Surgery, Erlangen (Germany); Pieber, Karin; Pflueger, Verena [Medical University of Vienna, Department of Physical Medicine and Rehabilitation, Vienna (Austria)

    2011-11-15

    To assess the feasibility of T2 mapping of lumbar facet joints and intervertebral discs in a single imaging slab and to compare the findings with morphological grading. Sixty lumbar spine segments from 10 low back pain patients and 5 healthy volunteers were examined by axial T2 mapping and morphological MRI at 3.0 Tesla. Regions of interest were drawn on a single slice for the facet joints and the intervertebral discs (nucleus pulposus, anterior and posterior annulus fibrosus). The Weishaupt grading was used for facet joints and the Pfirrmann score was used for morphological disc grading (''normal'' vs. ''abnormal'' discs). The inter-rater agreement was excellent for the facet joint T2 evaluation (r = 0.85), but poor for the morphological Weishaupt grading (kappa = 0.15). The preliminary results show similar facet joint T2 values in segments with normal and abnormal Pfirrmann scores. There was no difference in mean T2 values between facet joints in different Weishaupt grading groups. Facet joint T2 values showed a weak correlation with T2 values of the posterior annulus (r = 0.32) This study demonstrates the feasibility of a combined T2 mapping approach for the facet joints and intervertebral discs using a single axial slab. (orig.)

  17. Relationship between streaming potential and compressive stress in bovine intervertebral tissue.

    Science.gov (United States)

    Fujisaki, Kazuhiro; Tadano, Shigeru; Asano, Nozomu

    2011-09-02

    The intervertebral disc is formed by the nucleus pulposus (NP) and annulus fibrosus (AF), and intervertebral tissue contains a large amount of negatively charged proteoglycan. When this tissue becomes deformed, a streaming potential is induced by liquid flow with positive ions. The anisotropic property of the AF tissue is caused by the structural anisotropy of the solid phase and the liquid phase flowing into the tissue with the streaming potential. This study investigated the relationship between the streaming potential and applied stress in bovine intervertebral tissue while focusing on the anisotropy and loading location. Column-shaped specimens, 5.5 mm in diameter and 3 mm thick, were prepared from the tissue of the AF, NP and the annulus-nucleus transition region (AN). The loading direction of each specimen was oriented in the spinal axial direction, as well as in the circumferential and radial directions of the spine considering the anisotropic properties of the AF tissue. The streaming potential changed linearly with stress in all specimens. The linear coefficients k(e) of the relationship between stress and streaming potential depended on the extracted positions. These coefficients were not affected by the anisotropy of the AF tissue. In addition, these coefficients were lower in AF than in NP specimens. Except in the NP specimen, the k(e) values were higher under faster compression rate conditions. In cyclic compression loading the streaming potential changed linearly with compressive stress, regardless of differences in the tissue and load frequency.

  18. GlyRα2, not GlyRα3, modulates the receptive field surround of OFF retinal ganglion cells.

    Science.gov (United States)

    Zhang, Chi; Nobles, Regina D; McCall, Maureen A

    2015-01-01

    Receptive fields (RFs) of most retinal ganglion cells (RGCs) consist of an excitatory center and suppressive surround. The RF center arises from the summation of excitatory bipolar cell glutamatergic inputs, whereas the surround arises from lateral inhibitory inputs. In the retina, both gamma amino butyric acid (GABA) and glycine are inhibitory neurotransmitters. A clear role for GABAergic inhibition modulating the RGC RF surround has been demonstrated across species. Glycinergic inhibition is more commonly associated with RF center modulation, although there is some evidence that it may contribute to the RF surround. The synaptic glycinergic chloride channels are formed by three homomeric β and two homomeric α subunits that can be glycine receptor (GlyR) α1, α2, α3, or α4. GlyRα composition is responsible for currents with distinct decay kinetics. Their expression within the inner plexiform laminae and neuronal subtypes also differ. We studied the role of GlyR subunit selective modulation of RGC RF surrounds, using mice lacking GlyRα2 (Glra2 -/-), GlyRα3 (Glra3 -/-), or both (Glra2/3 -/-). We chose this molecular genetic approach instead of pharmacological manipulation because there are no subunit selective antagonists and strychnine blocks all GlyRs. Comparisons of annulus-evoked responses among wild type (WT) and GlyRα knockouts (Glra2 -/-, Glra3 -/- and Glra2/3 -/-) show that GlyRα2 inhibition enhances RF surround suppression and post-stimulus excitation in only WT OFF RGCs. Similarities in the responses in Glra2 -/- and Glra2/3 -/- RGCs verify these conclusions. Based on previous and current data, we propose that GlyRα2-mediated input uses a crossover inhibitory circuit. Further, we suggest that GlyRα2 modulates the OFF RGC RF center and surround independently. In summary, our results define a selective GlyR subunit-specific control of RF surround suppression in OFF RGCs.

  19. Stem Cells

    Directory of Open Access Journals (Sweden)

    Madhukar Thakur

    2015-02-01

    Full Text Available Objective: The objective of this presentation is to create awareness of stem cell applications in the ISORBE community and to foster a strategy of how the ISORBE community can disseminate information and promote the use of radiolabeled stem cells in biomedical applications. Methods: The continued excitement in Stem Cells, in many branches of basic and applied biomedical science, stems from the remarkable ability of stem cells to divide and develop into different types of cells in the body. Often called as Magic Seeds, stem cells are produced in bone marrow and circulate in blood, albeit at a relatively low concentration. These virtues together with the ability of stem cells to grow in tissue culture have paved the way for their applications to generate new and healthy tissues and to replace diseased or injured human organs. Although possibilities of stem cell applications are many, much remains yet to be understood of these remarkable magic seeds. Conclusion: This presentation shall briefly cover the origin of stem cells, the pros and cons of their growth and division, their potential application, and shall outline some examples of the contributions of radiolabeled stem cells, in this rapidly growing branch of biomedical science

  20. The ultra-structural organization of the elastic network in the intra- and inter-lamellar matrix of the intervertebral disc.

    Science.gov (United States)

    Tavakoli, J; Elliott, D M; Costi, J J

    2017-08-01

    The inter-lamellar matrix (ILM)-located between adjacent lamellae of the annulus fibrosus-consists of a complex structure of elastic fibers, while elastic fibers of the intra-lamellar region are aligned predominantly parallel to the collagen fibers. The organization of elastic fibers under low magnification, in both inter- and intra-lamellar regions, was studied by light microscopic analysis of histologically prepared samples; however, little is known about their ultrastructure. An ultrastructural visualization of elastic fibers in the inter-lamellar matrix is crucial for describing their contribution to structural integrity, as well as mechanical properties of the annulus fibrosus. The aims of this study were twofold: first, to present an ultrastructural analysis of the elastic fiber network in the ILM and intra-lamellar region, including cross section (CS) and in-plane (IP) lamellae, of the AF using Scanning Electron Microscopy (SEM) and second, to -compare the elastic fiber orientation between the ILM and intra-lamellar region. Four samples (lumbar sheep discs) from adjacent sections (30μm thickness) of anterior annulus were partially digested by a developed NaOH-sonication method for visualization of elastic fibers by SEM. Elastic fiber orientation and distribution were quantified relative to the tangential to circumferential reference axis. Visualization of the ILM under high magnification revealed a dense network of elastic fibers that has not been previously described. Within the ILM, elastic fibers form a complex network, consisting of different size and shape fibers, which differed to those located in the intra-lamellar region. For both regions, the majority of fibers were oriented near 0° with respect to tangential to circumferential (TCD) direction and two minor symmetrical orientations of approximately±45°. Statistically, the orientation of elastic fibers between the ILM and intra-lamellar region was not different (p=0.171). The present study used

  1. Types of Stem Cells

    Science.gov (United States)

    ... Stem Cell Glossary Search Toggle Nav Types of Stem Cells Stem cells are the foundation from which all ... Learn About Stem Cells > Types of Stem Cells Stem cells Stem cells are the foundation for every organ ...

  2. Fuel Cells

    DEFF Research Database (Denmark)

    Smith, Anders; Pedersen, Allan Schrøder

    2014-01-01

    Fuel cells have been the subject of intense research and development efforts for the past decades. Even so, the technology has not had its commercial breakthrough yet. This entry gives an overview of the technological challenges and status of fuel cells and discusses the most promising applications...... of the different types of fuel cells. Finally, their role in a future energy supply with a large share of fluctuating sustainable power sources, e.g., solar or wind, is surveyed....

  3. Fuel Cells

    Science.gov (United States)

    Hawkins, M. D.

    1973-01-01

    Discusses the theories, construction, operation, types, and advantages of fuel cells developed by the American space programs. Indicates that the cell is an ideal small-scale power source characterized by its compactness, high efficiency, reliability, and freedom from polluting fumes. (CC)

  4. Stem Cells

    DEFF Research Database (Denmark)

    Sommerlund, Julie

    2004-01-01

    '. This paper is about tech-noscience, and about the proliferation of connections and interdependencies created by it.More specifically, the paper is about stem cells. Biotechnology in general has the power to capture the imagination. Within the field of biotechnology nothing seems more provocative...... and tantalizing than stem cells, in research, in medicine, or as products....

  5. Stem cells.

    Science.gov (United States)

    Redi, Carlo Alberto; Monti, Manuela; Merico, Valeria; Neri, Tui; Zanoni, Mario; Zuccotti, Maurizio; Garagna, Silvia

    2007-01-01

    The application of stem cells to regenerative medicine is one of the actual hot topics in biomedicine. This research could help the cure of a number of diseases that are affecting a large share of the population. Some good results in cell replacement have already been obtained (infarcted heart, diabetes, Parkinson disease), apart from those of more traditional applications like severe burns and blood tumors. We are now facing crucial questions in stem cell biology. One of the key questions is how a cell begins to proliferate or differentiate. Genome reprogramming, both following nuclear transfer and cytoplast action, will likely highlight some of the molecular mechanisms of cell differentiation and dedifferentiation. In turn, these clues should be useful to the production of populations of reprogrammed cells that could develop into tissues or, in the future, into proper organs. We will overview what stem cells are, what roles they play in normal developmental processes and how stem cells could have the potential to treat diseases.

  6. Host cells and cell banking.

    Science.gov (United States)

    Stacey, Glyn N; Merten, Otto-Wilhelm

    2011-01-01

    Gene therapy based on the use of viral vectors is entirely dependent on the use of animal cell lines, mainly of mammalian origin, but also of insect origin. As for any biotechnology product for clinical use, viral -vectors have to be produced with cells derived from an extensively characterized cell bank to maintain the appropriate standard for assuring the lowest risk for the patients to be treated. Although many different cell types and lines have been used for the production of viral vectors, HEK293 cells or their derivatives have been extensively used for production of different vector types: adenovirus, oncorectrovirus, lentivirus, and AAV vectors, because of their easy handling and the possibility to grow them adherently in serum-containing medium as well as in suspension in serum-free culture medium. Despite this, these cells are not necessarily the best for the production of a given viral vector, and there are many other cell lines with significant advantages including superior growth and/or production characteristics, which have been tested and also used for the production of clinical vector batches. This chapter presents basic -considerations concerning the characterization of cell banks, in the first part, and, in the second part, practically all cell lines (at least when public information was available) established and developed for the production of the most important viral vectors (adenoviral, oncoretroviral, lentiviral, AAV, baculovirus).

  7. Sickle cell anemia

    Science.gov (United States)

    ... Anemia - sickle cell; Hemoglobin SS disease (Hb SS); Sickle cell disease Images Red blood cells, sickle cell Red blood cells, normal Red blood ... multiple sickle cells Red blood cells, sickle cells Red blood cells, sickle and ... Heeney MM, Ware RE. Sickle cell disease. In: Orkin SH, Fisher DE, Ginsburg D, Look ...

  8. The fern sporangium: a unique catapult.

    OpenAIRE

    Noblin, X.; Rojas, N. O.; Westbrook, J; Llorens, C.; Argentina, M.; Dumais, J.

    2012-01-01

    International audience; Various plants and fungi have evolved ingenious devices to disperse their spores. One such mechanism is the cavitation-triggered catapult of fern sporangia. The spherical sporangia enclosing the spores are equipped with a row of 12 to 13 specialized cells, the annulus. When dehydrating, these cells induce a dramatic change of curvature in the sporangium, which is released abruptly after the cavitation of the annulus cells. The entire ejection process is reminiscent of ...

  9. Cell, cell, cell: fuel cell applications moving ahead

    Energy Technology Data Exchange (ETDEWEB)

    Ross, E.

    2001-11-01

    Developments in fuel cell technology within the last decade, such as the targeting by major automakers of non-polluting fuel cells as an alternative to the internal combustion engine, are reviewed. For example, Ballard Power Systems of Vancouver is the exclusive supplier to both DaimlerCrysler and the Ford Motor Company of the fuel cell stacks that produce the power in fuel cell systems. Ballard plans the commercial launch of transit bus engines in 2002 and automotive products between 2003 and 2005. The company also sees huge opportunities for fuel cells in stationary and portable power applications. At the same time, the Calgary-based fuel cell division of Energy Ventures Inc. is developing a direct methanol fuel cell that eliminates the intermediate step of 'reforming' methanol into hydrogen that is required in the Ballard process. Energy Ventures targets small niche markets such as small utility vehicles for its direct methanol fuel cell. A completely self-contained fuel cell of this type is expected to be ready in 2002. Solid oxide fuel cells for off-grid remote power units as well as for home heat and power is yet another field of development that will be particularly attractive to operations in remote areas where reliable grid electricity is expensive and hard to obtain. A prototype 2.3 kW residential power system using natural gas was made available by Global Thermoelectric Inc in June 2001; field testing is planned for 2002, with commercial production in late 2003 or 2004. The Calgary-based Snow Leopard Resources Inc plans to use pure hydrogen sulphide obtained from sour natural gas as a hydrogen source. The prime focus of Snow Leopard is on gas plants looking for ways to increase their efficiency, obtain carbon dioxide credits and generate electricity on site. This type of fuel cell also could be of interest to companies with shut-in sour gas since these companies could use the stationary fuel cell system to generate electricity.

  10. Bi-Cell Unit for Fuel Cell.

    Science.gov (United States)

    The patent concerns a bi-cell unit for a fuel cell . The bi-cell unit is comprised of two electrode packs. Each of the electrode packs includes an...invention relates in general to a bi-cell unit for a fuel cell and in particular, to a bi-cell unit for a hydrazine-air fuel cell .

  11. Learn About Stem Cells

    Science.gov (United States)

    ... Patient Handbook Stem Cell Glossary Search Toggle Nav Stem Cell Basics Stem cells are the foundation from which ... original cell’s DNA, cytoplasm and cell membrane. About stem cells Stem cells are the foundation of development in ...

  12. Fuel cells

    Directory of Open Access Journals (Sweden)

    D. N. Srivastava

    1962-05-01

    Full Text Available The current state of development of fuel cells as potential power sources is reviewed. Applications in special fields with particular reference to military requirements are pointed out.

  13. T Cells

    Science.gov (United States)

    ... Informed d Corporate Support Corporate Partners National Teams Partnership Opportunities d Personal Stories Ambassadors & Familiar Faces Life ... d Our Healthcare Voice Home What Is MS? Definition of MS T Cells Share this page Facebook ...

  14. Steady Flow of a Second-Grade Fluid in an Annulus with Porous Walls

    Directory of Open Access Journals (Sweden)

    M. Emin Erdoğan

    2008-01-01

    Full Text Available An exact solution of an incompressible second-grade fluid for flow between two coaxial cylinders with porous walls is given. It is assumed that the inner cylinder is rotating with a constant angular velocity and the outer one is at rest. The solution is expressed in terms of the confluent hypergeometric functions and it is valid for all values of the cross-Reynolds number and the elastic number. The solutions for −2, +∞, and −∞ values of the cross-Reynolds number are obtained and a comparison with those of the Newtonian fluid is given. Furthermore, the torque exerted by the fluid on the inner cylinder is calculated. It is shown that the moment coefficient depends on the cross-Reynolds number, the elastic number, and the ratio of the radii of the cylinders. The variation of the moment coefficient with these numbers is discussed.

  15. Surface Structure in an Accretion Disk Annulus with Comparable Radiation and Gas Pressure

    CERN Document Server

    Blaes, Omer; Krolik, Julian H

    2007-01-01

    We have employed a 3-d energy-conserving radiation MHD code to simulate the vertical structure and thermodynamics of a shearing box whose parameters were chosen so that the radiation and gas pressures would be comparable. The upper layers of this disk segment are magnetically-dominated, creating conditions appropriate for both photon bubble and Parker instabilities. We find little evidence for photon bubbles, even though the simulation has enough spatial resolution to see them and their predicted growth rates are high. On the other hand, there is strong evidence for Parker instabilities, and they appear to dominate the evolution of the magnetically supported surface layers. The disk photosphere is complex, with large density inhomogeneities at both the scattering and effective (thermalization) photospheres of the evolving horizontally-averaged structure. Both the dominant magnetic support and the inhomogeneities are likely to have strong effects on the spectrum and polarization of thermal photons emerging fro...

  16. Solid Phase Characterization of Tank 241-AY-102 Annulus Space Particulate

    Energy Technology Data Exchange (ETDEWEB)

    Cooke, G. A.

    2013-01-30

    The Special Analytical Studies Group at the 222-S Laboratory (222-S) examined the particulate recovered from a series of samples from the annular space of tank 241-AY-102 (AY-102) using solid phase characterization (SPC) methods. These include scanning electron microscopy (SEM) using the ASPEX®1 scanning electron microscope, X-ray diffraction (XRD) using the Rigaku®2 MiniFlex X-ray diffractometer, and polarized light microscopy (PLM) using the Nikon®3 Eclipse Pol optical microscope. The SEM is equipped with an energy dispersive X-ray spectrometer (EDS) to provide chemical information.

  17. Thermocapillary flow instabilities in an annulus under microgravity — results of the experiment magia

    Science.gov (United States)

    Schwabe, D.; Benz, S.

    We investigated thermocapillary flow in an annular gap with outer heater container of radius R 1 = 40 mm and inner cooled cylinder of R 2 = 20 mm and with an adjustable height h, 2.5 ≤ h ≤ 20 mm. The gap was filled flat up to the rim with the 0.65 cSt silicone oil hexamethyldisiloxane (Prandtl number Pr = 6.7). The temperature differences ΔT, 0 K ≤ ΔT ≤ 40 K between outer and inner wall generated thermocapillary flow in the free upper surface and various flow structures have been observed under microgravity. We identified hydrothermal waves for small h and more complicated oscillations for larger h. For small h and small ΔT the multiroll structure was visible via IR-images of the free surface: concentric steady convection rolls with the same sense of rotation, embedded into the main thermocapillary roll. We measured the critical Marangoni number Ma c for the transition to time-dependent flow in the aspect ratio range A = h/(R 1 - R 2), 0.125 ≤ A ≤ 1, where it was virtually constant Ma c ≈ 5 · 10 4. We report and discuss a steady temperature asymmetry, changing its direction from time to time, as recorded by the IR-camera. This symmetry breaking is most probably due to slowly changing residual acceleration in the satellite.

  18. NUMERICAL STUDY OF THE MIXED CONVECTION HEAT TRANSFER IN ANNULUS HEATED BY JOULEAN EFFECT

    Directory of Open Access Journals (Sweden)

    S Touahri

    2015-12-01

    Full Text Available In the present work, we numerically study the three-dimensional mixed convection heat transfer in the annular space between tow concentric horizontal pipes, the external pipe is heated by an electrical intensity passing through its small thickness while the inner cylinder is insulated. The convection in the fluid domain is conjugated to thermal conduction in the pipes solid thickness. The physical properties of the fluid are thermal dependant. The heat losses from the external outside pipe surface to the surrounding ambient are considered. The model equations of continuity, momenta and energy are numerically solved by a finite volume method with a second order spatiotemporal discretization. The obtained results show the three dimensional aspect of the thermal and dynamical fields with considerable variations of the viscosity and moderate variations of the fluid thermal conductivity. As expected, the mixed convection Nusselt number becomes more superior to that of the forced convection when the Grashof number is increased. At the solid-fluid interface, the results show clearly the azimuthal and axial variations of the local heat flux and the local Nusselt numbers. Following these results, we have tried modelling the average Nusselt numberNuA as a function of Richardson numberRi. With the parameters used, the heat transfer is quantified by the correlation:NuA= 9.9130 Ri0.0816.

  19. CONJUGATE HEAT TRANSFER WITH VARIABLE FLUID PROPERTIES IN A HORIZONTAL ANNULUS

    Directory of Open Access Journals (Sweden)

    S TOUAHRI

    2010-12-01

    Full Text Available In the present work, we numerically study the three-dimensional conjugate heat transfer in an annular space between two horizontal concentric cylinders; the outer cylinder is subjected to an internal energy generated by Joule effect through its thickness while the inner is adiabatic. The thermal convection in the fluid domain is conjugated to the thermal conduction in the solid. The physical properties of the fluid are thermal dependant. The heat losses from the external outside pipe surface to the surrounding ambient are considered. The model equations of continuity, momenta and energy are numerically solved by a finite volume method with a second order spatiotemporal discretization. The obtained results show the three dimensional aspect of the thermal and dynamical fields with considerable variations of the viscosity and moderate variations of the fluid thermal conductivity. As expected, the mixed convection Nusselt number becomes more superior to that of the forced convection when the Grashof number is increased. At the solid-fluid interface, the results show clearly the azimuthal and axial variations of the local heat flux and the local Nusselt numbers. Following these results, we have tried modelling the average Nusselt number as a function of Richardson number. With the parameters used, the heat transfer is quantified by the correlation:  Nua = 12.8678 Ri (pui 01426

  20. Unsteady MHD two-phase Couette flow of fluid-particle suspension in an annulus

    Directory of Open Access Journals (Sweden)

    Basant K. Jha

    2011-12-01

    Full Text Available The problem of two-phase unsteady MHD flow between two concentric cylinders of infinite length has been analysed when the outer cylinder is impulsively started. The system of partial differential equations describing the flow problem is formulated taking the viscosity of the particle phase into consideration. Unified closed form expressions are obtained for the velocities and the skin frictions for both cases of the applied magnetic field being fixed to either the fluid or the moving outer cylinder. The problem is solved using a combination of the Laplace transform technique, D’Alemberts and the Riemann-sum approximation methods. The solution obtained is validated by comparisons with the closed form solutions obtained for the steady states which has been derived separately. The governing equations are also solved using the implicit finite difference method to verify the present proposed method. The variation of the velocity and the skin friction with the dimensionless parameters occuring in the problem are illustrated graphically and discussed for both phases.

  1. Parametric Study of Mixed Convective RadiativeHeat Transfer in an Inclined Annulus

    Directory of Open Access Journals (Sweden)

    Raed G. Saihood

    2008-01-01

    Full Text Available The steady state laminar mixed convection and radiation through inclined rectangular duct with an interior circular tube is investigated numerically for a thermally and hydrodynamicaly fully developed flow. The two heat transfer mechanisms of convection and radiation are treated independently and simultaneously. The governing equations which used are continuity, momentum and energy equations. These equations are normalized and solved using the Vorticity-Stream function and the Body Fitted Coordinates (B.F.C methods. The finite difference approach with the Line Successive Over-Relaxation (LSOR method is used to obtain all the computational results. The (B.F.C method is used to generate the grid of the problem. A computer program (Fortran 90 is built to calculate the steady state Nusselt number (Nu for Aspect Ratio AR (0.55-1 and Geometry Ratio GR (0.1-0.9. The fluid Prandtl number is 0.7, Rayleigh number Ra = 400, Reynolds number Re = 100, Optical Thickness (0 ≤ t ≤ 10, Conduction- Radiation parameter (0 ≤ N ≤ 100 and Inclination angle λ = 45. For the range of parameters considered, results show that radiation enhance heat transfer. It is also indicated in the results that heat transfer from the surface of the circle exceeds that of the rectangular duct. Generally, Nu is increased with increasing GR, t and N but it decreased with AR increase. When the radiation effect added to the heat transfer mechanism, the heat transfer rate increased. This effect increased with increasing in GR and decreasing with AR. The increasing in radiation properties lead to increase the radiation effect. Tecplot 7 program was used to plot the curves which cleared these relations and isotherms and streamlines which illustrate the behavior of air through the channel and its variation with other parameters. A correlation equation is concluded to describe the radiation effect. Comparison of the results with the previous work shows a good agreement.

  2. Steady viscous flows in an annulus between two cylinders produced by vibrations of the inner cylinder

    CERN Document Server

    Ilin, K

    2010-01-01

    We study the steady streaming between two infinitely long circular cylinders produced by small amplitude transverse vibrations of the inner cylinder about the axis of the outer cylinder. The Vishik-Lyusternik method is employed to construct an asymptotic expansion of the solution of the Navier-Stokes equations in the limit of high-frequency vibrations for Reynolds numbers of order of unity. The effect of the Stokes drift of fluid particles is also studied. It is shown that it is nonzero not only within the boundary layers but also in higher order terms of the expansion of the averaged outer flow.

  3. Design of a vertical annulus with MHD flow using entropy generation analysis

    Directory of Open Access Journals (Sweden)

    Mahian Omid

    2013-01-01

    Full Text Available Optimal design of a heat exchanger is one of the concerns of energy conversion engineers. In the present work, the mixed convection flow between two vertical concentric pipes with constant heat flux at the boundaries and MHD flow effects is considered. To determine the optimal design for such a heat exchanger, at first, the momentum and energy equations are simplified and solved analytically. Next, using entropy generation analysis and cost analysis, the operational costs due to entropy generation are estimated. It is concluded that with an increase in the Hartmann number, the energy costs increase. In addition, for two small deviations from the base radius ratio 2(=P including 9.1=P and 1.2=P , the changes in the energy cost are calculated. It is found that for 9.1=P the energy cost increases by 17.5% while for P = 2.1 the energy cost is reduced by 13.6 %.

  4. Laminar forced convection slip-flow in a micro-annulus between two concentric cylinders

    Energy Technology Data Exchange (ETDEWEB)

    Avci, Mete; Aydin, Orhan [Karadeniz Technical University, Department of Mechanical Engineering, 61080 Trabzon (Turkey)

    2008-07-01

    Forced convection heat transfer in hydrodynamically and thermally fully developed flows of viscous dissipating gases in annular microducts between two concentric micro cylinders is analyzed analytically. The viscous dissipation effect, the velocity slip and the temperature jump at the wall are taken into consideration. Two different cases of the thermal boundary conditions are considered: uniform heat flux at the outer wall and adiabatic inner wall (Case A) and uniform heat flux at the inner wall and adiabatic outer wall (Case B). Solutions for the velocity and temperature distributions and the Nusselt number are obtained for different values of the aspect ratio, the Knudsen number and the Brinkman number. The analytical results obtained are compared with those available in the literature and an excellent agreement is observed. (author)

  5. Dry cell battery poisoning

    Science.gov (United States)

    Batteries - dry cell ... Acidic dry cell batteries contain: Manganese dioxide Ammonium chloride Alkaline dry cell batteries contain: Sodium hydroxide Potassium hydroxide Lithium dioxide dry cell batteries ...

  6. Value of dobutamine stress tissue Doppler in evaluation of LV ...

    African Journals Online (AJOL)

    Shaimaa Ahmed Mostafa

    2014-12-12

    Dec 12, 2014 ... Prosthetic valve disease. Complicated PCI. LVEF less .... annulus moved toward the cardiac apex due to longitudinal contraction of the LV. ..... to fibrotic tissue is too high and also, improved the integrity of cardiac myocyte cell ...

  7. Electrochemical cell

    Science.gov (United States)

    Nagy, Zoltan; Yonco, Robert M.; You, Hoydoo; Melendres, Carlos A.

    1992-01-01

    An electrochemical cell has a layer-type or sandwich configuration with a Teflon center section that houses working, reference and counter electrodes and defines a relatively narrow electrolyte cavity. The center section is surrounded on both sides with thin Teflon membranes. The membranes are pressed in place by a pair of Teflon inner frames which are in turn supported by a pair of outer metal frames. The pair of inner and outer frames are provided with corresponding, appropriately shaped slits that are in plane generally transverse to the plane of the working electrode and permit X-ray beams to enter and exit the cell through the Teflon membranes that cover the slits so that the interface between the working electrode and the electrolyte within the cell may be analyzed by transmission geometry. In one embodiment, the center section consists of two parts, one on top of the other. Alternatively, the center section of the electrochemical cell may consist of two intersliding pieces or may be made of a single piece of Teflon sheet material. The electrolyte cavity is shaped so that the electrochemical cell can be rotated 90.degree. in either direction while maintaining the working and counter electrodes submerged in the electrolyte.

  8. Fuel cells:

    DEFF Research Database (Denmark)

    Sørensen, Bent

    2013-01-01

    A brief overview of the progress in fuel cell applications and basic technology development is presented, as a backdrop for discussing readiness for penetration into the marketplace as a solution to problems of depletion, safety, climate or environmental impact from currently used fossil and nucl......A brief overview of the progress in fuel cell applications and basic technology development is presented, as a backdrop for discussing readiness for penetration into the marketplace as a solution to problems of depletion, safety, climate or environmental impact from currently used fossil...... and nuclear fuel-based energy technologies....

  9. CellTracks cell analysis system for rare cell detection

    NARCIS (Netherlands)

    Kagan, Michael T.; Trainer, Michael N.; Bendele, Teresa; Rao, Chandra; Horton, Allen; Tibbe, Arjan G.; Greve, Jan; Terstappen, Leon W.M.M.

    2002-01-01

    The CellTracks system is a Compact Disk-based cell analyzer that, similar to flow cytometry, differentiates cells that are aligned while passing through focused laser beams. In CellTracks, only immuno-magnetically labeled cells are aligned and remain in position for further analysis. This feature is

  10. Tuning Collective Cell Migration by Cell-Cell Junction Regulation

    NARCIS (Netherlands)

    Friedl, P.; Mayor, R.

    2017-01-01

    Collective cell migration critically depends on cell-cell interactions coupled to a dynamic actin cytoskeleton. Important cell-cell adhesion receptor systems implicated in controlling collective movements include cadherins, immunoglobulin superfamily members (L1CAM, NCAM, ALCAM), Ephrin/Eph receptor

  11. Tuning Collective Cell Migration by Cell-Cell Junction Regulation

    NARCIS (Netherlands)

    Friedl, P.; Mayor, R.

    2017-01-01

    Collective cell migration critically depends on cell-cell interactions coupled to a dynamic actin cytoskeleton. Important cell-cell adhesion receptor systems implicated in controlling collective movements include cadherins, immunoglobulin superfamily members (L1CAM, NCAM, ALCAM), Ephrin/Eph

  12. Sickle Cell Anemia

    Science.gov (United States)

    Sickle cell anemia is a disease in which your body produces abnormally shaped red blood cells. The cells are shaped like ... normal, round red blood cells. This leads to anemia. The sickle cells also get stuck in blood ...

  13. Sickle Cell Disease

    Science.gov (United States)

    ... sickle cell disease?Sickle cell disease, also called sickle cell anemia, is a hereditary condition (which means it runs ... disease, hemoglobin SS disease, hemoglobin synthesis, hemoglobinopathies, ... cell anemia, sickle cell crisis, vaso-occlusive crisis Family Health, ...

  14. Potent Cells

    Science.gov (United States)

    Liu, Dennis

    2007-01-01

    It seems hard to believe that Dolly the cloned sheep was born 10 years ago, kindling furious arguments over the prospects and ethics of cloning a human. Today, the controversy over cloning is entwined, often confused, with concerns over the use of human embryonic stem cells. Most people are unclear what cloning is, and they know even less when it…

  15. Potent Cells

    Science.gov (United States)

    Liu, Dennis

    2007-01-01

    It seems hard to believe that Dolly the cloned sheep was born 10 years ago, kindling furious arguments over the prospects and ethics of cloning a human. Today, the controversy over cloning is entwined, often confused, with concerns over the use of human embryonic stem cells. Most people are unclear what cloning is, and they know even less when it…

  16. Electrochemical Cell

    DEFF Research Database (Denmark)

    1999-01-01

    The invention relates to a rechargeable electrochemical cell comprising a negative electrode, an electrolyte and a positive electrode in which the positive electrode structure comprises a lithium cobalt manganese oxide of the composition Li¿2?Co¿y?Mn¿2-y?O¿4? where 0

  17. Photovoltaic cell

    Science.gov (United States)

    Gordon, Roy G.; Kurtz, Sarah

    1984-11-27

    In a photovoltaic cell structure containing a visibly transparent, electrically conductive first layer of metal oxide, and a light-absorbing semiconductive photovoltaic second layer, the improvement comprising a thin layer of transition metal nitride, carbide or boride interposed between said first and second layers.

  18. Fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Enomoto, Hirofumi.

    1989-05-22

    This invention aims to maintain a long-term operation with stable cell output characteristics by uniformly supplying an electrolyte from the reserver to the matrix layer over the entire matrix layer, and further to prevent the excessive wetting of the catalyst layer by smoothly absorbing the volume change of the electrolyte, caused by the repeated stop/start-up of the fuel cell, within the reserver system. For this purpose, in this invention, an electrolyte transport layer, which connects with an electrolyte reservor formed at the electrode end, is partly formed between the electrode material and the catalyst layer; a catalyst layer, which faces the electrolyte transport layer, has through-holes, which connect to the matrix, dispersely distributed. The electrolyte-transport layer is a thin sheet of a hydrophilic fibers which are non-wovens of such fibers as carbon, silicon carbide, silicon nitride or inorganic oxides. 11 figs.

  19. Ghost cell lesions

    Directory of Open Access Journals (Sweden)

    E Rajesh

    2015-01-01

    Full Text Available Ghost cells have been a controversy for a long time. Ghost cell is a swollen/enlarged epithelial cell with eosnophilic cytoplasm, but without a nucleus. In routine H and E staining these cells give a shadowy appearance. Hence these cells are also called as shadow cells or translucent cells. The appearance of these cells varies from lesion to lesion involving odontogenic and nonodontogenic lesions. This article review about the origin, nature and significance of ghost cells in different neoplasms.

  20. [Inflammatory dendritic cells].

    Science.gov (United States)

    Segura, Elodie; Amigorena, Sebastian

    2014-01-01

    Dendritic cells are a rare and heterogeneous population of professional antigen-presenting cells. Several murine dendritic cell subpopulations have been identified that differ in their phenotype and functional properties. In the steady state, committed dendritic cell precursors differentiate into lymphoid organ-resident dendritic cells and migratory tissue dendritic cells. During inflammation appears an additional dendritic cell subpopulation that has been termed « inflammatory dendritic cells ». Inflammatory dendritic cells differentiate in situ from monocytes recruited to the site of inflammation. Here, we discuss how mouse inflammatory dendritic cells differ from macrophages and from other dendritic cell populations. Finally, we review recent work on human inflammatory dendritic cells.

  1. Red blood cells, sickle cell (image)

    Science.gov (United States)

    Sickle cell anemia is an inherited blood disease in which the red blood cells produce abnormal pigment (hemoglobin). ... abnormal hemoglobin causes deformity of the red blood cells into crescent or sickle-shapes, as seen in this photomicrograph.

  2. Red blood cells, multiple sickle cells (image)

    Science.gov (United States)

    Sickle cell anemia is an inherited disorder in which abnormal hemoglobin (the red pigment inside red blood cells) is produced. The abnormal hemoglobin causes red blood cells to assume a sickle shape, like the ones seen in this photomicrograph.

  3. CellFinder: a cell data repository

    OpenAIRE

    Stachelscheid, H.; Seltmann, S.; Lekschas, F.; Fontaine, J.F.; Mah, N.; Neves, M.; Andrade-Navarro, M.A.; Leser, U; Kurtz, A.

    2014-01-01

    CellFinder (http://www.cellfinder.org) is a comprehensive one-stop resource for molecular data characterizing mammalian cells in different tissues and in different development stages. It is built from carefully selected data sets stemming from other curated databases and the biomedical literature. To date, CellFinder describes 3394 cell types and 50 951 cell lines. The database currently contains 3055 microscopic and anatomical images, 205 whole-genome expression profiles of 194 cell/tissue t...

  4. Molluscan cells in culture: primary cell cultures and cell lines

    OpenAIRE

    2013-01-01

    In vitro cell culture systems from molluscs have significantly contributed to our basic understanding of complex physiological processes occurring within or between tissue-specific cells, yielding information unattainable using intact animal models. In vitro cultures of neuronal cells from gastropods show how simplified cell models can inform our understanding of complex networks in intact organisms. Primary cell cultures from marine and freshwater bivalve and gastropod species are used as bi...

  5. Electrorefining cell evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Bronson, M.C.; Thomas, R.L. (ed.)

    1989-04-14

    Operational characteristics of the LANL electrorefining cell, a modified LANL electrorefining cell, and an advanced electrorefining cell (known as the CRAC cell) were determined. Average process yields achieved were: 75% for the LANL cell, 82% for the modified LANL cell, and 86% for the CRAC cell. All product metal from the LANL and modified LANL cells was within foundry specifications. Metal from one run in the CRAC cell exceeded foundry specifications for tantalum. The LANL and modified LANL cells were simple in design and operation, but product separation was more labor intensive than with the CRAC cell. The CRAC cell was more complicated in design but remained relatively simple in operation. A decision analysis concluded that the modified LANL cell was the preferred cell. It was recommended that the modified LANL cell be implemented by the Plutonium Recovery Project at Rocky Flats and that development of the CRAC cell continue. 8 refs., 22 figs., 12 tabs.

  6. Antiparietal cell antibody test

    Science.gov (United States)

    APCA; Anti-gastric parietal cell antibody; Atrophic gastritis - anti-gastric parietal cell antibody; Gastric ulcer - anti-gastric parietal cell antibody; Pernicious anemia - anti-gastric parietal cell antibody; ...

  7. Sickle cell test

    Science.gov (United States)

    ... abnormal hemoglobin that causes sickle cell disease and sickle cell trait. Hemoglobin is a protein in red blood cells ... has two abnormal hemoglobin S genes. A person with sickle cell trait has only one of these abnormal genes and ...

  8. Molluscan cells in culture: primary cell cultures and cell lines.

    Science.gov (United States)

    Yoshino, T P; Bickham, U; Bayne, C J

    2013-06-01

    In vitro cell culture systems from molluscs have significantly contributed to our basic understanding of complex physiological processes occurring within or between tissue-specific cells, yielding information unattainable using intact animal models. In vitro cultures of neuronal cells from gastropods show how simplified cell models can inform our understanding of complex networks in intact organisms. Primary cell cultures from marine and freshwater bivalve and gastropod species are used as biomonitors for environmental contaminants, as models for gene transfer technologies, and for studies of innate immunity and neoplastic disease. Despite efforts to isolate proliferative cell lines from molluscs, the snail Biomphalaria glabrata Say, 1818 embryonic (Bge) cell line is the only existing cell line originating from any molluscan species. Taking an organ systems approach, this review summarizes efforts to establish molluscan cell cultures and describes the varied applications of primary cell cultures in research. Because of the unique status of the Bge cell line, an account is presented of the establishment of this cell line, and of how these cells have contributed to our understanding of snail host-parasite interactions. Finally, we detail the difficulties commonly encountered in efforts to establish cell lines from molluscs and discuss how these difficulties might be overcome.

  9. DNA-cell conjugates

    Science.gov (United States)

    Hsiao, Shih-Chia; Francis, Matthew B.; Bertozzi, Carolyn; Mathies, Richard; Chandra, Ravi; Douglas, Erik; Twite, Amy; Toriello, Nicholas; Onoe, Hiroaki

    2016-05-03

    The present invention provides conjugates of DNA and cells by linking the DNA to a native functional group on the cell surface. The cells can be without cell walls or can have cell walls. The modified cells can be linked to a substrate surface and used in assay or bioreactors.

  10. Optimizing cell viability in dropletbased cell deposition

    NARCIS (Netherlands)

    Hendriks, Jan; Visser, C.W.; Henke, S.J.; Leijten, Jeroen Christianus Hermanus; Saris, Daniël B.F.; Sun, Chao; Lohse, Detlef; Karperien, Hermanus Bernardus Johannes

    2015-01-01

    Biofabrication commonly involves the use of liquid droplets to transport cells to the printed structure. However, the viability of the cells after impact is poorly controlled and understood, hampering applications including cell spraying, inkjet bioprinting, and laser-assisted cell transfer. Here,

  11. Skin Stem Cells in Skin Cell Therapy

    Directory of Open Access Journals (Sweden)

    Mollapour Sisakht

    2015-12-01

    Full Text Available Context Preclinical and clinical research has shown that stem cell therapy is a promising therapeutic option for many diseases. This article describes skin stem cells sources and their therapeutic applications. Evidence Acquisition Compared with conventional methods, cell therapy reduces the surgical burden for patients because it is simple and less time-consuming. Skin cell therapy has been developed for variety of diseases. By isolation of the skin stem cell from the niche, in vitro expansion and transplantation of cells offers a surprising healing capacity profile. Results Stem cells located in skin cells have shown interesting properties such as plasticity, transdifferentiation, and specificity. Mesenchymal cells of the dermis, hypodermis, and other sources are currently being investigated to promote regeneration. Conclusions Because skin stem cells are highly accessible from autologous sources and their immunological profile is unique, they are ideal for therapeutic approaches. Optimization of administrative routes requires more investigation own to the lack of a standard protocol.

  12. Molecular Mechanisms of Cell-cell Recognition

    Institute of Scientific and Technical Information of China (English)

    WANG Jia-Huai

    2004-01-01

    Cell-cell recognition is the key for multicellular organisms to survive. This recognition critically depends on protein-protein interactions from opposing cell surfaces. Recent structural investigations reveal unique features of these cell surface receptors and how they interact. These interactions are specific, but usually relatively weak, with more hydrophilic forces involved in binding. The receptors appear to have specialized ways to present their key interacting elements for ligand-binding from the cell surface. Cell-cell contacts are multivalent. A large group of cell surface molecules are engaged in interactions. Characteristic weak interactions make possible for each individual molecule pair within the group to constantly associate-dissociate-reassociate, such that the cell-cell recognition becomes a dynamic process. The immunological synapse is a good example for immune receptors to be orchestrated in performing immunological function in a collective fashion.

  13. Photoelectrochemical cell

    Energy Technology Data Exchange (ETDEWEB)

    Rauh, R. David (Newton, MA); Boudreau, Robert A. (Norton, MA)

    1983-06-14

    A photoelectrochemical cell comprising a sealed container having a light-transmitting window for admitting light into the container across a light-admitting plane, an electrolyte in the container, a photoelectrode in the container having a light-absorbing surface arranged to receive light from the window and in contact with the electrolyte, the surface having a plurality of spaced portions oblique to the plane, each portion having dimensions at least an order of magnitude larger than the maximum wavelength of incident sunlight, the total surface area of the surface being larger than the area of the plane bounded by the container, and a counter electrode in the container in contact with the electrolyte.

  14. NKT Cell Responses to B Cell Lymphoma

    Directory of Open Access Journals (Sweden)

    Junxin Li

    2014-04-01

    Full Text Available Natural killer T (NKT cells are a unique subset of CD1d-restricted T lymphocytes that express characteristics of both T cells and natural killer cells. NKT cells mediate tumor immune-surveillance; however, NKT cells are numerically reduced and functionally impaired in lymphoma patients. Many hematologic malignancies express CD1d molecules and co-stimulatory proteins needed to induce anti-tumor immunity by NKT cells, yet most tumors are poorly immunogenic. In this study, we sought to investigate NKT cell responses to B cell lymphoma. In the presence of exogenous antigen, both mouse and human NKT cell lines produce cytokines following stimulation by B cell lymphoma lines. NKT cell populations were examined ex vivo in mouse models of spontaneous B cell lymphoma, and it was found that during early stages, NKT cell responses were enhanced in lymphoma-bearing animals compared to disease-free animals. In contrast, in lymphoma-bearing animals with splenomegaly and lymphadenopathy, NKT cells were functionally impaired. In a mouse model of blastoid variant mantle cell lymphoma, treatment of tumor-bearing mice with a potent NKT cell agonist, α-galactosylceramide (α-GalCer, resulted in a significant decrease in disease pathology. Ex vivo studies demonstrated that NKT cells from α-GalCer treated mice produced IFN-γ following α-GalCer restimulation, unlike NKT cells from vehicle-control treated mice. These data demonstrate an important role for NKT cells in the immune response to an aggressive hematologic malignancy like mantle cell lymphoma.

  15. nduced pluripotent stem cells and cell therapy

    Directory of Open Access Journals (Sweden)

    Banu İskender

    2013-12-01

    Full Text Available Human embryonic stem cells are derived from the inner cell mass of a blastocyst-stage embryo. They hold a huge promise for cell therapy with their self-renewing ability and pluripotency, which is known as the potential to differentiate into all cell types originating from three embryonic germ layers. However, their unique pluripotent feature could not be utilised for therapeutic purposes due to the ethical and legal problems during derivation. Recently, it was shown that the cells from adult tissues could be reverted into embryonic state, thereby restoring their pluripotent feature. This has strenghtened the possiblity of directed differentition of the reprogrammed somatic cells into the desired cell types in vitro and their use in regenerative medicine. Although these cells were termed as induced pluripotent cells, the mechanism of pluripotency has yet to be understood. Still, induced pluripotent stem cell technology is considered to be significant by proposing novel approaches in disease modelling, drug screening and cell therapy. Besides their self-renewing ability and their potential to differentiate into all cell types in a human body, they arouse a great interest in scientific world by being far from the ethical concerns regarding their embryonic counterparts and their unique feature of being patient-specific in prospective cell therapies. In this review, induced pluripotent stem cell technology and its role in cell-based therapies from past to present will be discussed. J Clin Exp Invest 2013; 4 (4: 550-561

  16. Modeling cell-in-cell structure into its biological significance

    OpenAIRE

    He, M-f; Wang, S.; Wang, Y; Wang, X-N.

    2013-01-01

    Although cell-in-cell structure was noted 100 years ago, the molecular mechanisms of ‘entering' and the destination of cell-in-cell remain largely unclear. It takes place among the same type of cells (homotypic cell-in-cell) or different types of cells (heterotypic cell-in-cell). Cell-in-cell formation affects both effector cells and their host cells in multiple aspects, while cell-in-cell death is under more intensive investigation. Given that cell-in-cell has an important role in maintainin...

  17. Tumor cell "dead or alive": caspase and survivin regulate cell death, cell cycle and cell survival.

    Science.gov (United States)

    Suzuki, A; Shiraki, K

    2001-04-01

    Cell death and cell cycle progression are two sides of the same coin, and these two different phenomenons are regulated moderately to maintain the cellular homeostasis. Tumor is one of the disease states produced as a result of the disintegrated regulation and is characterized as cells showing an irreversible progression of cell cycle and a resistance to cell death signaling. Several investigations have been performed for the understanding of cell death or cell cycle, and cell death research has remarkably progressed in these 10 years. Caspase is a nomenclature referring to ICE/CED-3 cysteine proteinase family and plays a central role during cell death. Recently, several investigations raised some possible hypotheses that caspase is also involved in cell cycle regulation. In this issue, therefore, we review the molecular basis of cell death and cell cycle regulated by caspase in tumor, especially hepatocellular carcinoma cells.

  18. Nanostructured Solar Cells.

    Science.gov (United States)

    Chen, Guanying; Ning, Zhijun; Ågren, Hans

    2016-08-09

    We are glad to announce the Special Issue "Nanostructured Solar Cells", published in Nanomaterials. This issue consists of eight articles, two communications, and one review paper, covering major important aspects of nanostructured solar cells of varying types. From fundamental physicochemical investigations to technological advances, and from single junction solar cells (silicon solar cell, dye sensitized solar cell, quantum dots sensitized solar cell, and small molecule organic solar cell) to tandem multi-junction solar cells, all aspects are included and discussed in this issue to advance the use of nanotechnology to improve the performance of solar cells with reduced fabrication costs.

  19. Cell death pathways in directly irradiated cells and cells exposed to medium from irradiated cells.

    Science.gov (United States)

    Jella, Kishore Kumar; Garcia, Amaya; McClean, Brendan; Byrne, Hugh J; Lyng, Fiona M

    2013-03-01

    The aim of this study was to compare levels of apoptosis, necrosis, mitotic cell death and senescence after treatment with both direct radiation and irradiated cell conditioned medium. Human keratinocytes (HaCaT cell line) were irradiated (0.005, 0.05 and 0.5 Gy) using a cobalt 60 teletherapy unit. For bystander experiments, the medium was harvested from donor HaCaT cells 1 hour after irradiation and transferred to recipient HaCaT cells. Clonogenic assay, apoptosis, necrosis, mitotic cell death, senescence and cell cycle analysis were measured in both directly irradiated cells and bystander cells A reduction in cell survival was observed for both directly irradiated cells and irradiated cell conditioned medium (ICCM)-treated cells. Early apoptosis and necrosis was observed predominantly after direct irradiation. An increase in the number of cells in G2/M phase was observed at 6 and 12 h which led to mitotic cell death after 72 h following direct irradiation and ICCM treatment. No senescence was observed in the HaCaT cell line following either direct irradiation or treatment with ICCM. This study has shown that directly irradiated cells undergo apoptosis, necrosis and mitotic cell death whereas ICCM-treated cells predominantly undergo mitotic cell death.

  20. Cell culture purity issues and DFAT cells

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Shengjuan [College of Animal Science and Technology, Northwest A and F University, Yangling, Shaanxi Province 712100 (China); Department of Animal Sciences, Washington State University, Pullman, WA 99164 (United States); Bergen, Werner G. [Program in Cellular and Molecular Biosciences/Department of Animal Sciences, Auburn University, Auburn, AL 36849 (United States); Hausman, Gary J. [Animal Science Department, University of Georgia, Athens, GA 30602-2771 (United States); Zan, Linsen, E-mail: zanls@yahoo.com.cn [College of Animal Science and Technology, Northwest A and F University, Yangling, Shaanxi Province 712100 (China); Dodson, Michael V., E-mail: dodson@wsu.edu [Department of Animal Sciences, Washington State University, Pullman, WA 99164 (United States)

    2013-04-12

    Highlights: •DFAT cells are progeny cells derived from dedifferentiated mature adipocytes. •Common problems in this research is potential cell contamination of initial cultures. •The initial cell culture purity is crucial in DFAT cell research field. -- Abstract: Dedifferentiation of mature adipocytes, in vitro, has been pursued/documented for over forty years. The subsequent progeny cells are named dedifferentiated adipocyte-derived progeny cells (DFAT cells). DFAT cells are proliferative and likely to possess mutilineage potential. As a consequence, DFAT cells and their progeny/daughter cells may be useful as a potential tool for various aspects of tissue engineering and as potential vectors for the alleviation of several disease states. Publications in this area have been increasing annually, but the purity of the initial culture of mature adipocytes has seldom been documented. Consequently, it is not always clear whether DFAT cells are derived from dedifferentiated mature (lipid filled) adipocytes or from contaminating cells that reside in an impure culture.

  1. Electrochemical cell

    Energy Technology Data Exchange (ETDEWEB)

    Heuts, J.J.F.G.; Willems, J.J.G.S.A.

    1987-10-13

    An electrochemical cell is described comprising a negative electrode. The electrochemically active material of which consists of an intermetallic compound forming a hydride with hydrogen, which compound has the CaCu/sub 5/-structure and the compositional formula AB/sub m/C/sub n/, where m+n is between 4.8 and 5.4, where n is between 0.05 and 0.6, in which A consists of Misch-metal or of one or more elements selected from the group consisting of Y, Ti, Hf, Zr, Ca, Th, La and the remaining rare earth metals, in which the total atomic quantities of the elements Y, Ti, Hf and Zr may not be more than 40% of A. B consists of two or more elements selected from the group formed by Ni, Co, Cu, Fe and Mn, where the maximum atomic quantity per gram atom of A is for Ni: 3.5, for Co:3.5, for Cu:3.5, for Fe:2.0 and for Mn:1.0, and C consists of one or more elements selected from the group formed by Al, Cr and Si in the indicated atomic quantities: Al:0.05-0.6, Cr:0.05-0.5 and Si:0.05-0.5, characterized in that the electrochemically active material additionally comprises one or more metals selected from the group formed by Pd, Pt, Ir and Rh, the atomic quantity per gram atom of A being from 0.001 to 0.5.

  2. CELL RESEARCH

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    REVIEWSInducible resistance to Fas-mediated apoptosis in B cells…………………………………ROTHSTEIN Thomas L (245)Executionary pathway for apoptosis: lessons from mutant mice………………………………………WOO Minna, Razqallah Hakem, Tak W Mak (267)The SHP-2 tyrosine phosphatase: Signaling mechanisms and biological functions…………………………………QU Cheng Kui (279)REGULAR ARTICLESTemperature dependent expression of cdc2 and cyclin B1 in spermatogenic cells during spermatogenesis…………………………KONG Wei Hua, Zheng GU, Jining LU, Jiake TSO (289)Transgenic mice overexpressing γ-aminobutyric acid transporter subtype I develop obesity…………………………………MA Ying Hua, Jia Hua HU, Xiao Gang ZHOU, Ruo Wang ZENG, Zhen Tong MEI, Jian FEI, Li He GUO (303)Genetic aberration in primary hepatocellular carcinoma: correlation between p53 gene mutation and loss-of-heterozygosity on chromosome 16q21-q23 and 9p21-p23………………………………………WANG Gang, Chang Hui HUANG, Yan ZHAO, Ling CAI, Ying WANG, Shi Jin XIU, Zheng Wen JIANG, Shuang YANG, Xin Tai ZHAO, Wei HUANG, Jian Ren GU (311)Identification and genetic mapping of four novel genes that regulate leaf deve- lopment in Arabidopsis………………………………………………SUN Yue, Wei ZHANG, Feng Ling LI, Ying Li GUO, Tian Lei LIU, Hai HUANG (325)NOTICE FOR CONTRIBUTORS…………………………………(337)CONTENTS of Vol. 10, 2000…………………………………………………(338)

  3. Mammary stem cells have myoepithelial cell properties

    Science.gov (United States)

    Prater, Michael D.; Petit, Valérie; Russell, I. Alasdair; Giraddi, Rajshekhar; Shehata, Mona; Menon, Suraj; Schulte, Reiner; Kalajzic, Ivo; Rath, Nicola; Olson, Michael F.; Metzger, Daniel; Faraldo, Marisa M.; Deugnier, Marie-Ange; Glukhova, Marina A.; Stingl, John

    2014-01-01

    Contractile myoepithelial cells dominate the basal layer of the mammary epithelium and are considered to be differentiated cells. However, we observe that up to 54% of single basal cells can form colonies when seeded into adherent culture in the presence of agents that disrupt acin-myosin interactions, and on average, 65% of the single-cell-derived basal colonies can repopulate a mammary gland when transplanted in vivo. This indicates that a high proportion of basal myoepithelial cells can give rise to a mammary repopulating unit (MRU). We demonstrate that myoepithelial cells, flow-sorted using 2 independent myoepithelial-specific reporter strategies, have MRU capacity. Using an inducible lineage tracing approach we follow the progeny of α-smooth muscle actin-expressing myoepithelial cells and show that they function as long-lived lineage-restricted stem cells in the virgin state and during pregnancy. PMID:25173976

  4. Mammary stem cells have myoepithelial cell properties.

    Science.gov (United States)

    Prater, Michael D; Petit, Valérie; Alasdair Russell, I; Giraddi, Rajshekhar R; Shehata, Mona; Menon, Suraj; Schulte, Reiner; Kalajzic, Ivo; Rath, Nicola; Olson, Michael F; Metzger, Daniel; Faraldo, Marisa M; Deugnier, Marie-Ange; Glukhova, Marina A; Stingl, John

    2014-10-01

    Contractile myoepithelial cells dominate the basal layer of the mammary epithelium and are considered to be differentiated cells. However, we observe that up to 54% of single basal cells can form colonies when seeded into adherent culture in the presence of agents that disrupt actin-myosin interactions, and on average, 65% of the single-cell-derived basal colonies can repopulate a mammary gland when transplanted in vivo. This indicates that a high proportion of basal myoepithelial cells can give rise to a mammary repopulating unit (MRU). We demonstrate that myoepithelial cells, flow-sorted using two independent myoepithelial-specific reporter strategies, have MRU capacity. Using an inducible lineage-tracing approach we follow the progeny of myoepithelial cells that express α-smooth muscle actin and show that they function as long-lived lineage-restricted stem cells in the virgin state and during pregnancy.

  5. Cell culture purity issues and DFAT cells.

    Science.gov (United States)

    Wei, Shengjuan; Bergen, Werner G; Hausman, Gary J; Zan, Linsen; Dodson, Michael V

    2013-04-12

    Dedifferentiation of mature adipocytes, in vitro, has been pursued/documented for over forty years. The subsequent progeny cells are named dedifferentiated adipocyte-derived progeny cells (DFAT cells). DFAT cells are proliferative and likely to possess mutilineage potential. As a consequence, DFAT cells and their progeny/daughter cells may be useful as a potential tool for various aspects of tissue engineering and as potential vectors for the alleviation of several disease states. Publications in this area have been increasing annually, but the purity of the initial culture of mature adipocytes has seldom been documented. Consequently, it is not always clear whether DFAT cells are derived from dedifferentiated mature (lipid filled) adipocytes or from contaminating cells that reside in an impure culture.

  6. Cell Membrane Softening in Cancer Cells

    Science.gov (United States)

    Schmidt, Sebastian; Händel, Chris; Käs, Josef

    Biomechanical properties are useful characteristics and