Science.gov

Sample records for derived vessel wall

  1. Culturing and applications of rotating wall vessel bioreactor derived 3D epithelial cell models.

    PubMed

    Radtke, Andrea L; Herbst-Kralovetz, Melissa M

    2012-04-03

    Cells and tissues in the body experience environmental conditions that influence their architecture, intercellular communications, and overall functions. For in vitro cell culture models to accurately mimic the tissue of interest, the growth environment of the culture is a critical aspect to consider. Commonly used conventional cell culture systems propagate epithelial cells on flat two-dimensional (2-D) impermeable surfaces. Although much has been learned from conventional cell culture systems, many findings are not reproducible in human clinical trials or tissue explants, potentially as a result of the lack of a physiologically relevant microenvironment. Here, we describe a culture system that overcomes many of the culture condition boundaries of 2-D cell cultures, by using the innovative rotating wall vessel (RWV) bioreactor technology. We and others have shown that organotypic RWV-derived models can recapitulate structure, function, and authentic human responses to external stimuli similarly to human explant tissues (1-6). The RWV bioreactor is a suspension culture system that allows for the growth of epithelial cells under low physiological fluid shear conditions. The bioreactors come in two different formats, a high-aspect rotating vessel (HARV) or a slow-turning lateral vessel (STLV), in which they differ by their aeration source. Epithelial cells are added to the bioreactor of choice in combination with porous, collagen-coated microcarrier beads (Figure 1A). The cells utilize the beads as a growth scaffold during the constant free fall in the bioreactor (Figure 1B). The microenvironment provided by the bioreactor allows the cells to form three-dimensional (3-D) aggregates displaying in vivo-like characteristics often not observed under standard 2-D culture conditions (Figure 1D). These characteristics include tight junctions, mucus production, apical/basal orientation, in vivo protein localization, and additional epithelial cell-type specific properties

  2. Three-Dimensional Rotating Wall Vessel-Derived Cell Culture Models for Studying Virus-Host Interactions

    PubMed Central

    Gardner, Jameson K.; Herbst-Kralovetz, Melissa M.

    2016-01-01

    The key to better understanding complex virus-host interactions is the utilization of robust three-dimensional (3D) human cell cultures that effectively recapitulate native tissue architecture and model the microenvironment. A lack of physiologically-relevant animal models for many viruses has limited the elucidation of factors that influence viral pathogenesis and of complex host immune mechanisms. Conventional monolayer cell cultures may support viral infection, but are unable to form the tissue structures and complex microenvironments that mimic host physiology and, therefore, limiting their translational utility. The rotating wall vessel (RWV) bioreactor was designed by the National Aeronautics and Space Administration (NASA) to model microgravity and was later found to more accurately reproduce features of human tissue in vivo. Cells grown in RWV bioreactors develop in a low fluid-shear environment, which enables cells to form complex 3D tissue-like aggregates. A wide variety of human tissues (from neuronal to vaginal tissue) have been grown in RWV bioreactors and have been shown to support productive viral infection and physiological meaningful host responses. The in vivo-like characteristics and cellular features of the human 3D RWV-derived aggregates make them ideal model systems to effectively recapitulate pathophysiology and host responses necessary to conduct rigorous basic science, preclinical and translational studies. PMID:27834891

  3. HIV-1 and recombinant gp120 affect the survival and differentiation of human vessel wall-derived mesenchymal stem cells.

    PubMed

    Gibellini, Davide; Alviano, Francesco; Miserocchi, Anna; Tazzari, Pier Luigi; Ricci, Francesca; Clò, Alberto; Morini, Silvia; Borderi, Marco; Viale, Pierluigi; Pasquinelli, Gianandrea; Pagliaro, Pasqualepaolo; Bagnara, Gian Paolo; Re, Maria Carla

    2011-05-25

    HIV infection elicits the onset of a progressive immunodeficiency and also damages several other organs and tissues such as the CNS, kidney, heart, blood vessels, adipose tissue and bone. In particular, HIV infection has been related to an increased incidence of cardiovascular diseases and derangement in the structure of blood vessels in the absence of classical risk factors. The recent characterization of multipotent mesenchymal cells in the vascular wall, involved in regulating cellular homeostasis, suggests that these cells may be considered a target of HIV pathogenesis. This paper investigated the interaction between HIV-1 and vascular wall resident human mesenchymal stem cells (MSCs). MSCs were challenged with classical R5 and X4 HIV-1 laboratory strains demonstrating that these strains are able to enter and integrate their retro-transcribed proviral DNA in the host cell genome. Subsequent experiments indicated that HIV-1 strains and recombinant gp120 elicited a reliable increase in apoptosis in sub-confluent MSCs. Since vascular wall MSCs are multipotent cells that may be differentiated towards several cell lineages, we challenged HIV-1 strains and gp120 on MSCs differentiated to adipogenesis and endotheliogenesis. Our experiments showed that the adipogenesis is increased especially by upregulated PPARγ activity whereas the endothelial differentiation induced by VEGF treatment was impaired with a downregulation of endothelial markers such as vWF, Flt-1 and KDR expression. These viral effects in MSC survival and adipogenic or endothelial differentiation were tackled by CD4 blockade suggesting an important role of CD4/gp120 interaction in this context. The HIV-related derangement of MSC survival and differentiation may suggest a direct role of HIV infection and gp120 in impaired vessel homeostasis and in genesis of vessel damage observed in HIV-infected patients.

  4. A garlic derivative, ajoene, inhibits platelet deposition on severely damaged vessel wall in an in vivo porcine experimental model.

    PubMed

    Apitz-Castro, R; Badimon, J J; Badimon, L

    1994-08-01

    Ajoene, (E,Z)-4,5,9-trithiadodeca-1,6,11-triene 9-oxide, is a potent antiplatelet compound isolated from alcoholic extracts of garlic. In vitro, ajoene reversibly inhibits platelet aggregation as well as the release reaction induced by all known agonists. We used a well characterized perfusion chamber to study the in vivo effects of ajoene on platelet deposition onto a highly thrombogenic, severely damaged arterial wall, obtained by stripping off the intimal layer and exposing tunica media. Platelet-vessel wall interaction and the effect of ajoene was studied under flow conditions of high and low local shear rate that mimics laminar blood flow in small and medium size arteries (1690 sec-1 and 212 sec-1). Our results indicate that administration of ajoene to heparinized animals, significantly prevents thrombus formation at local low blood shear rate. Ajoene does not inhibit binding of vWF to GPIb, therefore, it does not affect platelet adhesion. In fact, although ajoene impairs fibrinogen and vWF (less efficient) binding to GPlIb/IIIa, it does not totally inhibits platelet deposition to the substrates at any of the shear rates used in this study. Our present results, under in vivo flow conditions and in the presence of physiological calcium levels, suggest that ajoene may be potentially useful for the acute prevention of thrombus formation induced by severe vascular damage, mainly in arterial sites with local low shear rates.

  5. Role of Arginase in Vessel Wall Remodeling

    PubMed Central

    Durante, William

    2013-01-01

    Arginase metabolizes the semi-essential amino acid l-arginine to l-ornithine and urea. There are two distinct isoforms of arginase, arginase I and II, which are encoded by separate genes and display differences in tissue distribution, subcellular localization, and molecular regulation. Blood vessels express both arginase I and II but their distribution appears to be cell-, vessel-, and species-specific. Both isoforms of arginase are induced by numerous pathologic stimuli and contribute to vascular cell dysfunction and vessel wall remodeling in several diseases. Clinical and experimental studies have documented increases in the expression and/or activity of arginase I or II in blood vessels following arterial injury and in pulmonary and arterial hypertension, aging, and atherosclerosis. Significantly, pharmacological inhibition or genetic ablation of arginase in animals ameliorates abnormalities in vascular cells and normalizes blood vessel architecture and function in all of these pathological states. The detrimental effect of arginase in vascular remodeling is attributable to its ability to stimulate vascular smooth muscle cell and endothelial cell proliferation, and collagen deposition by promoting the synthesis of polyamines and l-proline, respectively. In addition, arginase adversely impacts arterial remodeling by directing macrophages toward an inflammatory phenotype. Moreover, the proliferative, fibrotic, and inflammatory actions of arginase in the vasculature are further amplified by its capacity to inhibit nitric oxide (NO) synthesis by competing with NO synthase for substrate, l-arginine. Pharmacologic or molecular approaches targeting specific isoforms of arginase represent a promising strategy in treating obstructive fibroproliferative vascular disease. PMID:23717309

  6. 2D Fast Vessel Visualization Using a Vessel Wall Mask Guiding Fine Vessel Detection

    PubMed Central

    Raptis, Sotirios; Koutsouris, Dimitris

    2010-01-01

    The paper addresses the fine retinal-vessel's detection issue that is faced in diagnostic applications and aims at assisting in better recognizing fine vessel anomalies in 2D. Our innovation relies in separating key visual features vessels exhibit in order to make the diagnosis of eventual retinopathologies easier to detect. This allows focusing on vessel segments which present fine changes detectable at different sampling scales. We advocate that these changes can be addressed as subsequent stages of the same vessel detection procedure. We first carry out an initial estimate of the basic vessel-wall's network, define the main wall-body, and then try to approach the ridges and branches of the vasculature's using fine detection. Fine vessel screening looks into local structural inconsistencies in vessels properties, into noise, or into not expected intensity variations observed inside pre-known vessel-body areas. The vessels are first modelled sufficiently but not precisely by their walls with a tubular model-structure that is the result of an initial segmentation. This provides a chart of likely Vessel Wall Pixels (VWPs) yielding a form of a likelihood vessel map mainly based on gradient filter's intensity and spatial arrangement parameters (e.g., linear consistency). Specific vessel parameters (centerline, width, location, fall-away rate, main orientation) are post-computed by convolving the image with a set of pre-tuned spatial filters called Matched Filters (MFs). These are easily computed as Gaussian-like 2D forms that use a limited range sub-optimal parameters adjusted to the dominant vessel characteristics obtained by Spatial Grey Level Difference statistics limiting the range of search into vessel widths of 16, 32, and 64 pixels. Sparse pixels are effectively eliminated by applying a limited range Hough Transform (HT) or region growing. Major benefits are limiting the range of parameters, reducing the search-space for post-convolution to only masked regions

  7. [Mircocarriers' motion in rotating wall vessels].

    PubMed

    Ma, Xiao; Yang, Chun; Zhuang, Fengyuan

    2010-12-01

    Rotating wall vessels (RWVS), an ingenious apparatus for three-dimensional suspension culture, is widely used to build a simulated microgravity-effect on cell. Independent researchers have proposed hypotheses to illustrate why RWVS can simulate certain aspects of microgravity. Many of the hypotheses stated that the culture condition in RWVS is determined by the cellular mechanical environment which is a result of low fluid shear and microcarrier's motion. The microcarrier's motions consist of primary and secondary motions. In the light of the analysis of forces loaded by the microcarriers, some conclusions are drawn from the data on microcarriers' primary and secondary motions about which many simulations and observations have already been conducted.

  8. Vessel wall characterization using quantitative MRI: what's in a number?

    PubMed

    Coolen, Bram F; Calcagno, Claudia; van Ooij, Pim; Fayad, Zahi A; Strijkers, Gustav J; Nederveen, Aart J

    2017-08-14

    The past decade has witnessed the rapid development of new MRI technology for vessel wall imaging. Today, with advances in MRI hardware and pulse sequences, quantitative MRI of the vessel wall represents a real alternative to conventional qualitative imaging, which is hindered by significant intra- and inter-observer variability. Quantitative MRI can measure several important morphological and functional characteristics of the vessel wall. This review provides a detailed introduction to novel quantitative MRI methods for measuring vessel wall dimensions, plaque composition and permeability, endothelial shear stress and wall stiffness. Together, these methods show the versatility of non-invasive quantitative MRI for probing vascular disease at several stages. These quantitative MRI biomarkers can play an important role in the context of both treatment response monitoring and risk prediction. Given the rapid developments in scan acceleration techniques and novel image reconstruction, we foresee the possibility of integrating the acquisition of multiple quantitative vessel wall parameters within a single scan session.

  9. Welded repairs of punctured thin-walled aluminum pressure vessels

    NASA Technical Reports Server (NTRS)

    Jones, D. J.

    1969-01-01

    Punctures in thin-walled aluminum pressure vessels are repaired by plugging the hole with an interference-fit disc and welding the unit. The repaired vessels withstood test pressures in excess of vessel ultimate design values for 2-, 4-, and 6-inch holes in 0.202-inch-thick aluminum alloy parent material.

  10. Hemoglobin alpha in the blood vessel wall

    PubMed Central

    Butcher, Joshua T.; Johnson, Tyler; Beers, Jody; Columbus, Linda; Isakson, Brant E

    2014-01-01

    Hemoglobin has been studied and well haracterized in red blood cells for over one hundred years. However, new work has indicated that the hemoglobin alpha subunit (Hbα) is also found within the blood vessel wall, where it appears to localize at the myoendothelial junction (MEJ) and plays a role in regulating nitric oxide (NO) signaling between endothelium and smooth muscle. This discovery has created a new paradigm for control of endothelial nitric oxide synthase activity, nitric oxide diffusion, and ultimately, control of vascular tone and blood pressure. This review will discuss the current knowledge of hemoglobin’s properties as a gas exchange molecule in the blood stream, and extrapolate the properties of Hbα biology to the MEJ signaling domain. Specifically, we propose that Hbα is present at the MEJ to regulate NO release and diffusion in a restricted physical space, which would have powerful implications for the regulation of blood flow in peripheral resistance arteries. PMID:24832680

  11. [Stem and progenitor cells in biostructure of blood vessel walls].

    PubMed

    Korta, Krzysztof; Kupczyk, Piotr; Skóra, Jan; Pupka, Artur; Zejler, Paweł; Hołysz, Marcin; Gajda, Mariusz; Nowakowska, Beata; Barć, Piotr; Dorobisz, Andrzej T; Dawiskiba, Tomasz; Szyber, Piotr; Bar, Julia

    2013-09-18

    Development of vascular and hematopoietic systems during organogenesis occurs at the same time. During vasculogenesis, a small part of cells does not undergo complete differentiation but stays on this level, "anchored" in tissue structures described as stem cell niches. The presence of blood vessels within tissue stem cell niches is typical and led to identification of niches and ensures that they are functioning. The three-layer biostructure of vessel walls for artery and vein, tunica: intima, media and adventitia, for a long time was defined as a mechanical barrier between vessel light and the local tissue environment. Recent findings from vascular biology studies indicate that vessel walls are dynamic biostructures, which are equipped with stem and progenitor cells, described as vascular wall-resident stem cells/progenitor cells (VW-SC/PC). Distinct zones for vessel wall harbor heterogeneous subpopulations of VW-SC/PC, which are described as "subendothelial or vasculogenic zones". Recent evidence from in vitro and in vivo studies show that prenatal activity of stem and progenitor cells is not only limited to organogenesis but also exists in postnatal life, where it is responsible for vessel wall homeostasis, remodeling and regeneration. It is believed that VW-SC/PC could be engaged in progression of vascular disorders and development of neointima. We would like to summarize current knowledge about mesenchymal and progenitor stem cell phenotype with special attention to distribution and biological properties of VW-SC/PC in biostructures of intima, media and adventitia niches. It is postulated that in the near future, niches for VW-SC/PC could be a good source of stem and progenitor cells, especially in the context of vessel tissue bioengineering as a new alternative to traditional revascularization therapies.

  12. The Study of Leukocyte Functions in a Rotating Wall Vessel

    NASA Technical Reports Server (NTRS)

    Trial, JoAnn

    1998-01-01

    The objective of this study was to investigate the behavior of leukocytes under free-fall conditions in a rotating wall vessel. In such a vessel, the tendency of a cell to fall in response to gravity is opposed by the rotation of the vessel and the culture medium within, keeping the cells in suspension without fluid shear. Previous reports indicated that such functions as lymphocyte migration through collagen matrix or monocyte cytokine secretion are altered under these conditions, and these changes correlate with similar functional defects of cultured cells seen during spaceflight.

  13. Detecting thermal discrepancies in vessel walls

    NASA Technical Reports Server (NTRS)

    Casscells, S. Ward (Inventor); Willerson, James T. (Inventor); Bearman, Gregory H. (Inventor); Eastwood, Michael L. (Inventor); Krabach, Timothy N. (Inventor)

    1999-01-01

    An infrared, heat-sensing catheter particularly useful for identifying potentially fatal arterial plaques in patients with disease of the coronary or other arteries and its use are detailed. In one embodiment, an infrared fiberoptic system (with or without ultrasound) is employed at the tip of the catheter to locate inflamed, heat-producing, atherosclerotic plaque, which is at greater risk for rupture, fissure, or ulceration, and consequent thrombosis and occlusion of the artery. In another embodiment, a catheter with an infrared detector (with or without ultrasound) employed at its tip will likewise locate inflamed heat-producing atherosclerotic plaque. The devices and methods of the invention may be used to detect abscesses, infection, and cancerous regions by the heat such regions differentially display over the ambient temperature of immediately adjacent tissues. The methods and devices of the invention may also be used to detect regions of cooler than ambient tissue in a vessel or organ which indicate cell death, thrombosis, cell death, hemorrhage, calcium or cholesterol accumulations, or foreign materials.

  14. Thick-wall Kevlar 49/Epoxy pressure vessels

    SciTech Connect

    Guess, T.R.

    1984-01-01

    The feasibility of thick-wall composite vessels for very high pressure applications is demonstrated. Prototype vessels, in both spherical and cylindrical geometries, were designed, fabricated and burst tested. It is shown that experimental burst pressures are in excellent agreement with predicted values for burst pressures up to 60 ksi. Each unit consisted of a thin, seamless, copper liner with stainless steel fill stems and a filament-wound Kevlar 49/epoxy outer shell. Analysis of vessel performance accounted for liner thickness and yield strengths, composite thickness, mechanical properties and fiber volume fraction, and stress concentrations caused by the fill stem. Spherical vessels of three different sizes (inside diameters of 2.15 inches, 4.0 inches and 5.3 inches) with either 30 ksi or 60 ksi design burst pressure are discussed. Also, cylindrical vessels with identical liners but of two different composite thicknesses are described. These vessels achieved 50 ksi and 57 ksi burst pressures, respectively. In addition to the design considerations alluded to throughout the paper, the stress state in a thin metal liner during cyclic loading and the life prediction of composite vessels under sustained loading are discussed.

  15. Cavitation distribution within large phantom vessel and mechanical damage formed on surrounding vessel wall.

    PubMed

    Qiao, Yangzi; Yin, Hui; Li, Zhaopeng; Wan, Mingxi

    2013-11-01

    Blood vessel is one of the most important targets encountered during focused ultrasound (FU) therapy. The lasting high temperature caused by continuous FU can result in structural modification of small vessel. For the vessel with a diameter larger than 2mm, convective cooling can significantly weaken the thermal effect of FU. Meanwhile, the continued presence of ultrasound will cause repetitive cavitation and acoustic microstreaming, making comprehension of continuous wave induced cavitation effect in large vessels necessary. The Sonoluminescence (SL) method, mechanical damage observation and high-speed camera were used in this study to investigate the combination effect of ultrasound contrast agents (UCAs) and continuous FU in large phantom vessels with a diameter of 10mm without consideration of thermal effect. When the focus was positioned at the proximal wall, cylindrical hole along the acoustic axis opposite the ultrasound wave propagation direction was observed at the input power equal to or greater than 50 W. When the focus was located at the distal wall, only small tunnels can be found. The place where the cylindrical hole formed was corresponding to where bubbles gathered and emitted brilliant light near the wall. Without UCAs neither such bright SL nor cylindrical hole can be found. However, the UCAs concentration had little influence on the SL distribution and the length of cylindrical hole. The SL intensity near the proximal vessel wall and the length of the cylindrical hole both increased with the input power. It is suggested that these findings need to be considered in the large vessel therapy and UCAs usage.

  16. Aluminum vacuum vessel/first wall concept for the CTHR

    SciTech Connect

    Culbert, M. E.

    1980-09-01

    The purpose of this investigation was to develop a design concept for a commercial tokamak hybrid reactor (CTHR) vacuum vessel/first wall system which satisfies the engineering requirements for a commercial environment. The hybrid reactor offers the unique condition that energy extraction from the first wall is not critical from the point of view of system economics. This allows the consideration of low temperature structural material for first wall application. Therefore, the CTHR aluminum vacuum vessel/first wall design philosophy was to utilize a low temperature design, thus minimizing the severe material and thermal stress problems associated with high temperature systems. The mechanical arrangement consists of a series of internally finned aluminum tubes fabricated into 30 sections and assembled around the torus. The coolant manifolds are at the top and bottom of the torus. The vessel sector length depends on the spacing between TF coils. Each sector is mounted on a rail system that permits translation for assembly or removal. The tubes in each sector are welded to tube sheets which are in turn welded to semi-cylindrical manifolds which distribute the coolant uniformly to the tubes.

  17. Optimized suspension culture: the rotating-wall vessel

    NASA Technical Reports Server (NTRS)

    Hammond, T. G.; Hammond, J. M.

    2001-01-01

    Suspension culture remains a popular modality, which manipulates mechanical culture conditions to maintain the specialized features of cultured cells. The rotating-wall vessel is a suspension culture vessel optimized to produce laminar flow and minimize the mechanical stresses on cell aggregates in culture. This review summarizes the engineering principles, which allow optimal suspension culture conditions to be established, and the boundary conditions, which limit this process. We suggest that to minimize mechanical damage and optimize differentiation of cultured cells, suspension culture should be performed in a solid-body rotation Couette-flow, zero-headspace culture vessel such as the rotating-wall vessel. This provides fluid dynamic operating principles characterized by 1) solid body rotation about a horizontal axis, characterized by colocalization of cells and aggregates of different sedimentation rates, optimally reduced fluid shear and turbulence, and three-dimensional spatial freedom; and 2) oxygenation by diffusion. Optimization of suspension culture is achieved by applying three tradeoffs. First, terminal velocity should be minimized by choosing microcarrier beads and culture media as close in density as possible. Next, rotation in the rotating-wall vessel induces both Coriolis and centrifugal forces, directly dependent on terminal velocity and minimized as terminal velocity is minimized. Last, mass transport of nutrients to a cell in suspension culture depends on both terminal velocity and diffusion of nutrients. In the transduction of mechanical culture conditions into cellular effects, several lines of evidence support a role for multiple molecular mechanisms. These include effects of shear stress, changes in cell cycle and cell death pathways, and upstream regulation of secondary messengers such as protein kinase C. The discipline of suspension culture needs a systematic analysis of the relationship between mechanical culture conditions and

  18. Optimized suspension culture: the rotating-wall vessel

    NASA Technical Reports Server (NTRS)

    Hammond, T. G.; Hammond, J. M.

    2001-01-01

    Suspension culture remains a popular modality, which manipulates mechanical culture conditions to maintain the specialized features of cultured cells. The rotating-wall vessel is a suspension culture vessel optimized to produce laminar flow and minimize the mechanical stresses on cell aggregates in culture. This review summarizes the engineering principles, which allow optimal suspension culture conditions to be established, and the boundary conditions, which limit this process. We suggest that to minimize mechanical damage and optimize differentiation of cultured cells, suspension culture should be performed in a solid-body rotation Couette-flow, zero-headspace culture vessel such as the rotating-wall vessel. This provides fluid dynamic operating principles characterized by 1) solid body rotation about a horizontal axis, characterized by colocalization of cells and aggregates of different sedimentation rates, optimally reduced fluid shear and turbulence, and three-dimensional spatial freedom; and 2) oxygenation by diffusion. Optimization of suspension culture is achieved by applying three tradeoffs. First, terminal velocity should be minimized by choosing microcarrier beads and culture media as close in density as possible. Next, rotation in the rotating-wall vessel induces both Coriolis and centrifugal forces, directly dependent on terminal velocity and minimized as terminal velocity is minimized. Last, mass transport of nutrients to a cell in suspension culture depends on both terminal velocity and diffusion of nutrients. In the transduction of mechanical culture conditions into cellular effects, several lines of evidence support a role for multiple molecular mechanisms. These include effects of shear stress, changes in cell cycle and cell death pathways, and upstream regulation of secondary messengers such as protein kinase C. The discipline of suspension culture needs a systematic analysis of the relationship between mechanical culture conditions and

  19. Viscoelasticity reduces the dynamic stresses and strains in the vessel wall: implications for vessel fatigue.

    PubMed

    Zhang, Wei; Liu, Yi; Kassab, Ghassan S

    2007-10-01

    The mechanical behavior of blood vessels is known to be viscoelastic rather than elastic. The functional role of viscoelasticity, however, has remained largely unclear. The hypothesis of this study is that viscoelasticity reduces the stresses and strains in the vessel wall, which may have a significant impact on the fatigue life of the blood vessel wall. To verify the hypothesis, the pulsatile stress in rabbit thoracic artery at physiological loading condition was investigated with a quasi-linear viscoelastic model, where the normalized stress relaxation function is assumed to be isotropic, while the stress-strain relationship is anisotropic and nonlinear. The artery was subjected to the same boundary condition, and the mechanical equilibrium equation was solved for both the viscoelastic and an elastic (which has a constant relaxation function) model. Numerical results show that, compared with purely elastic response, the viscoelastic property of arteries reduces the magnitudes and temporal variations of circumferential stress and strain. The radial wall movement is also reduced due to viscoelasticity. These findings imply that viscoelasticity may be beneficial for the fatigue life of blood vessels, which undergo millions of cyclic mechanical loadings each year of life.

  20. Three-dimensional ultrasound imaging of vessel wall for evaluating atherosclerosis risk and disease

    NASA Astrophysics Data System (ADS)

    Amin, Viren R.; Wang, Bo; Sonka, Milan; Lauer, Ronald M.

    2002-04-01

    This research aims at developing a three-dimensional (3D) ultrasound system for carotid and brachial artery scanning for evaluating vessel wall characteristics. In the long term, we seek to test hypothesis that the artery wall measurements of carotid intima-media-thickness and brachial flow mediated dilatation using 3D ultrasound data provide better repeatability than those derived from conventional 2D ultrasound scans. The approach is to implement a free-hand data acquisition scheme using conventional 2D medical ultrasound scanner, develop data processing algorithms for appropriately registering and displaying the volumetric ultrasound vessel scans, and develop techniques for measuring vessel wall characteristics. The system uses electromagnetic sensor mounted on the transducer to acquire position and orientation of each image slice as the transducer is moved freely to scan the area of interest. These non-parallel images are registered into a 3D dataset for reconstruction, segmentation, and measurements of the vessel wall structure. A simple calibration object is developed using a small stainless-steel sphere in a fixed position to perform coordinate transformations and pixel registration. A commercial 3D ultrasound tissue-mimicking phantom is used for assessment of freehand 3D data acquisition, calibration, registration, and visualization schemes. Early results of experimental carotid artery scans of volunteers are presented.

  1. Method and apparatus for detecting irregularities on or in the wall of a vessel

    DOEpatents

    Bowling, Michael Keith

    2000-09-12

    A method of detecting irregularities on or in the wall of a vessel by detecting localized spatial temperature differentials on the wall surface, comprising scanning the vessel surface with a thermal imaging camera and recording the position of the or each region for which the thermal image from the camera is indicative of such a temperature differential across the region. The spatial temperature differential may be formed by bacterial growth on the vessel surface; alternatively, it may be the result of defects in the vessel wall such as thin regions or pin holes or cracks. The detection of leaks through the vessel wall may be enhanced by applying a pressure differential or a temperature differential across the vessel wall; the testing for leaks may be performed with the vessel full or empty, and from the inside or the outside.

  2. Nanodiagnostics, nanopharmacology and nanotoxicology of platelet-vessel wall interactions.

    PubMed

    Tomaszewski, Krzysztof A; Radomski, Marek W; Santos-Martinez, Maria Jose

    2015-05-01

    In physiological conditions, the interactions between blood platelets and endothelial cells play a major role in vascular reactivity and hemostasis. By contrast, increased platelet activation contributes to the pathogenesis of vascular pathology such as atherosclerosis, thrombosis, diabetes mellitus, hypertension and carcinogenesis. Nanomedicine, including nanodiagnostics and nanotherapeutics is poised to be used in the management of vascular diseases. However, the inherent risk and potential toxicity resultant from the use of nanosized (<100 nm) materials need to be carefully considered. This review, basing on a systematic search of literature provides state-of-the-art and focuses on new discoveries, as well as the potential benefits and threats in the field of nanodiagnostics, nanopharmacology and nanotoxicology of platelet-vessel wall interactions.

  3. Surface layer composition of the JET vessel walls

    NASA Astrophysics Data System (ADS)

    Behrisch, R.; Martinelli, A. P.; Grigull, S.; Grötzschel, R.; Kreissig, U.; Hildebrandt, D.; Schneider, W.

    1995-04-01

    After the 1990/91 discharge period several samples have been cut from the JET vessel walls, the carbon and the beryllium limiters, and the carbon and the beryllium X-point divertor tiles. The surface layers of these samples have been analysed in detail by ion beam techniques, such as PIXE, HIERDA, RBS, SIMS and Sputter-Auger for the absolute amounts as well as for the depth distributions of the different deposits. The major deposits are H, D, Be, C and O, as well as other impurities, such as Ni, Cr, Fe, and C. From the measurements on the carbon samples it was found that the oxygen deposits correlate with the Be deposits, while the measurements on the Be samples show that the C deposits correlate with the D deposits, indicating a codeposition of these elements. In addition H concentrations mostly larger than the D concentrations are measured. These may partly originate also from adsorption during the exposure to air.

  4. Regulation of Cellular Communication by Signaling Microdomains in the Blood Vessel Wall

    PubMed Central

    Billaud, Marie; Lohman, Alexander W.; Johnstone, Scott R.; Biwer, Lauren A.; Mutchler, Stephanie; Isakson, Brant E.

    2014-01-01

    It has become increasingly clear that the accumulation of proteins in specific regions of the plasma membrane can facilitate cellular communication. These regions, termed signaling microdomains, are found throughout the blood vessel wall where cellular communication, both within and between cell types, must be tightly regulated to maintain proper vascular function. We will define a cellular signaling microdomain and apply this definition to the plethora of means by which cellular communication has been hypothesized to occur in the blood vessel wall. To that end, we make a case for three broad areas of cellular communication where signaling microdomains could play an important role: 1) paracrine release of free radicals and gaseous molecules such as nitric oxide and reactive oxygen species; 2) role of ion channels including gap junctions and potassium channels, especially those associated with the endothelium-derived hyperpolarization mediated signaling, and lastly, 3) mechanism of exocytosis that has considerable oversight by signaling microdomains, especially those associated with the release of von Willebrand factor. When summed, we believe that it is clear that the organization and regulation of signaling microdomains is an essential component to vessel wall function. PMID:24671377

  5. Physical properties of resistance vessel wall in peripheral blood flow regulation--I. Mathematical model.

    PubMed

    Iida, N

    1989-01-01

    A mathematical model is introduced to investigate the influence of the physical properties of the resistance vessel wall on the metabolic and myogenic mechanisms. The resistance vessel wall is assumed to have an elastic property and the elastic modulus to be a function of pressure (myogenic) and flow (metabolic). Blood is Poiseuille's flow. The resulting mathematical equations for pressure-flow, pressure-diameter, pressure-wall tension and pressure-wall elastic modulus relationships introduced obey Laplace's law. Poiseuille's law and Hooke's law. In comparison with the experimental data (pressure diameter), the mathematical model is confirmed to explain well the dynamic behavior of the resistance vessel wall in vivo.

  6. Engineering of the human vessel wall with hair follicle stem cells in vitro.

    PubMed

    Xu, Zhi-Cheng; Zhang, Qun; Li, Hong

    2017-01-01

    Hair follicle stem cells (HFSCs) are increasingly used as a stem cell paradigm in vascular tissue engineering due to the fact that they are a rich source of easily accessible multipotent adult stem cells. Promising results have been demonstrated with small diameter (less than 6 mm) tissue engineered blood vessels under low blood pressure, however engineering large vessels (>6 mm in diameter) remains a challenge due to the fact it demands a higher number of seed cells and higher quality biomechanical properties. The aim of the current study was to engineer a large vessel (6 mm in diameter) with differentiated smooth muscle cells (SMCs) induced from human (h)HFSCs using transforming growth factor‑β1 and platelet‑derived growth factor BB in combination with low‑serum culture medium. The cells were seeded onto polyglycolic acid and then wrapped around a silicone tube and further cultured in vitro. A round vessel wall was formed subsequent to 8 weeks of culture. Histological examination indicated that layers of smooth muscle‑like cells and collagenous fibres were oriented in the induced group. In contrast, disorganised cells and collagenous fibres were apparent in the undifferentiated group. The approach developed in the current study demonstrated potential for constructing large muscular vessels with differentiated SMCs induced from hHFSCs.

  7. Study of the Neutron Flux and Dpa Attenuation in the Reactor Pressure-Vessel Wall

    SciTech Connect

    Remec, I.

    1999-06-01

    The study of the neutron flux and dpa attenuation in the reactor pressure vessel (PV) wall presented in this work was performed with state-of-the art methods currently used to determine PV fluxes, the BUGLE-96 cross-section library, and the iron displacement cross sections derived from ENDF/B-VI data. The calculations showed that the RG 1.99, Rev. 2, extrapolation formula predicts slower--and therefore conservative--attenuation of the neutron flux (E > 1MeV) in the PV wall. More importantly, the calculations gave slower attenuation of the dpa rate in the PV wall than the attenuation predicted by the formula. The slower dpa rate attenuation was observed for all the cases considered, which included two different PWRs, and several configurations obtained by varying the PV wall thickness and thermal shield thickness. For example, for a PV wall thickness of {approximately}24 cm, the calculated ratio of the dpa rate at 1/4 and 3/4 of the PV wall thickness to the dpa value on the inner PV surface is {approximately}14% and 19% higher, respectively, than predicted by the RG 1.99, Rev. 2, formula.

  8. Neuroendocrine Tissue Engineering in Rotating Wall Vessel Bioreactors Under Simulated Microgravity Conditions

    DTIC Science & Technology

    2001-10-25

    NEUROENDOCRINE TISSUE ENGINEERING IN ROTATING WALL VESSEL BIOREACTORS UNDER SIMULATED MICROGRAVITY CONDITIONS P.I. Lelkes1, 4, N. Akhtar2, E...Abstract-The low-shear, microgravity-simulating cell culture environment in Rotating Wall Vessel (RWV) Bioreactors RWV Bioreactors is well...microscopy. The unique culture environment of RWV Bioreactors facilitates the generation of macroscopic, functional neuroendocrine tissue-like

  9. Engineered bone tissue associated with vascularization utilizing a rotating wall vessel bioreactor.

    PubMed

    Nishi, Masanori; Matsumoto, Rena; Dong, Jian; Uemura, Toshimasa

    2013-02-01

    Tissue-engineered bone has attracted much attention as an alternative material for bone grafting; however, implantable bone tissue of an appropriate size and shape for clinical use has not yet been developed due to a lack of vascularization, which results in necrosis of the seeded cells in vivo. This is the first report of bone tissue engineering associated with vascularization by co-culturing bone marrow mesenchymal stem cells (MSCs) with MSC-derived endothelial cells (ECs) within a porous scaffold using a rotating wall vessel (RWV) bioreactor. MSC-derived ECs were identified by immunofluorescence staining for von Willebrand factor (vWF) and by flow cytometry for CD31 expression. The tissue obtained was histochemically analyzed using toluidin blue, hematoxylin and eosin, anti-osteopontin antibody, anti-osteocalcin antibody, and tomato-lectin stain. Results showed that bone tissue containing vascular-like structures was generated. Three-dimensional culture condition created by medium flow in the RWV vessel and the interaction of MSCs with MSC-derived ECs might provide the cells an advantage in the construction of three-dimensional bone tissue with blood vessels.

  10. Estimation of the radial force on the tokamak vessel wall during fast transient events

    SciTech Connect

    Pustovitov, V. D.

    2016-11-15

    The radial force balance in a tokamak during fast transient events with a duration much shorter than the resistive time of the vacuum vessel wall is analyzed. The aim of the work is to analytically estimate the resulting integral radial force on the wall. In contrast to the preceding study [Plasma Phys. Rep. 41, 952 (2015)], where a similar problem was considered for thermal quench, simultaneous changes in the profiles and values of the pressure and plasma current are allowed here. Thereby, the current quench and various methods of disruption mitigation used in the existing tokamaks and considered for future applications are also covered. General formulas for the force at an arbitrary sequence or combination of events are derived, and estimates for the standard tokamak model are made. The earlier results and conclusions are confirmed, and it is shown that, in the disruption mitigation scenarios accepted for ITER, the radial forces can be as high as in uncontrolled disruptions.

  11. Vessel wall perforation mechanism of the excimer laser-assisted non-occlusive anastomosis technique.

    PubMed

    Bremmer, Jochem; van Doormaal, Tristan P C; Verweij, Bon H; van der Zwan, Albert; Tulleken, Cornelius A F; Verdaasdonk, Rudolf

    2016-08-01

    The excimer laser assisted non-occlusive anastomosis (ELANA) technique is used to make anastomoses on intracerebral arteries. This end-to-side anastomosis is created without temporary occlusion of the recipient artery using a 308-nm excimer laser with a ring-shaped multi-fiber catheter to punch an opening in the arterial wall. Over 500 patients have received an ELANA bypass. However, the vessel wall perforation mechanism of the laser catheter is not known exactly and not 100 % successful. In this study, we aimed to understand the mechanism of ELANA vessel perforation using specialized imaging techniques to ultimately improve its effectiveness. High-speed imaging, high-contrast imaging, and high-sensitivity thermal imaging were used to study the laser wall perforation mechanism and reveal the mechanical and thermal effects involved. In vitro, rabbit arteries were exposed with the special designed laser catheter in a setup representative for the clinical setting, in which blood was replaced with a transparent UV absorbing liquid for visualization. We observed that laser vessel wall perforation was caused by explosive vapor bubbles tearing through the vessel wall, mostly within the first 20 of the total 200 pulses. Thermal effects were minimal. Unsymmetrical tension in the vessel wall inducing migration of the flap during laser exposure was observed in case of unsuccessful wall perforations. The laser wall perforation mechanism in the ELANA technique is primarily mechanical. Symmetric tension in the recipient vessel wall is essential and should be trained by neurosurgeons.

  12. Vessel wall-embedded dendritic cells induce T-cell autoreactivity and initiate vascular inflammation.

    PubMed

    Han, Ji W; Shimada, Kazunori; Ma-Krupa, Wei; Johnson, Tiffany L; Nerem, Robert M; Goronzy, Jörg J; Weyand, Cornelia M

    2008-03-14

    Human medium-sized and large arteries are targeted by inflammation with innate and adaptive immune responses occurring within the unique microspace of the vessel wall. How 3D spatial arrangements influence immune recognition and cellular response thresholds and which cell populations sense immunoactivating ligands and function as antigen-presenting cells are incompletely understood. To mimic the 3D context of human arteries, bioartificial arteries were engineered from collagen type I matrix, human vascular smooth muscle cells (VSMCs), and human endothelial cells and populated with cells implicated in antigen presentation and T-cell stimulation, including monocytes, macrophages, and myeloid dendritic cells (DCs). Responsiveness of wall-embedded antigen-presenting cells was probed with the Toll-like receptor ligand lipopolysaccharide, and inflammation was initiated by adding autologous CD4(+) T cells. DCs colonized the outermost VSMC layer, recapitulating their positioning at the media-adventitia border of normal arteries. Wall-embedded DCs responded to the microbial product lipopolysaccharide by entering the maturation program and upregulating the costimulatory ligand CD86. Activated DCs effectively stimulated autologous CD4 T cells, which produced the proinflammatory cytokine interferon-gamma and infiltrated deeply into the VSMC layer, causing matrix damage. Lipopolysaccharide-triggered macrophages were significantly less efficacious in recruiting T cells and promoting T-cell stimulation. CD14(+) monocytes, even when preactivated, failed to support initial steps of vascular wall inflammation. Innate immune cells, including monocytes, macrophages, and DCs, display differential functions in the vessel wall. DCs are superior in sensing pathogen-derived motifs and are highly efficient in breaking T-cell tolerance, guiding T cells toward proinflammatory and tissue-invasive behavior.

  13. 302 Vessel Wall Enhancement on Magnetic Resonance Imaging After Stent-Retriever Thrombectomy.

    PubMed

    Abraham, Peter; Cheung, Vincent J; Lee, Roland; Pannell, Jeffrey Scott; Gupta, Mihir; Rennert, Robert; Khalessi, Alexander Arash

    2016-08-01

    Animal and in vitro studies have demonstrated histologic iatrogenic endothelial injury after stent-retriever thrombectomy. However, noncontrast vessel wall magnetic resonance imaging (MRI) studies have failed to demonstrate vessel injury. Our prospective study examines iatrogenic endothelial damage after stent-retriever thrombectomy in vivo utilizing high-resolution contrast-enhanced vessel wall MRI (VW-MRI). We evaluated 11 patients, including postthrombectomy and control subjects, on a Signa HDx 3.0-T MRI scanner with an 8-channel head coil. Pre- and postcontrast T1-weighted CUBE vessel wall images and MR angiograms were acquired with attention to the Circle of Willis. Parenchymal imaging included diffusion, susceptibility, and T2 fluid attenuated inversion recovery (FLAIR)-weighted images. The primary end point was vessel wall enhancement, as determined by 2 independent, blinded board-certified neuroradiologists before examination of parenchymal imaging. Additional covariates were age, National Institutes of Health Stroke Scale, level of occlusion, stroke etiology, devices utilized, number of passes required for thrombectomy, TICI reperfusion score, stroke volume, and 90-day modified Rankin Scale (mRS). Post-contrast T1-weighted vessel wall enhancement was detected in the middle cerebral artery (MCA) M2 segment in 100%, the M1 segment in 83%, and the internal carotid artery in 50% of thrombectomy patients. One patient demonstrated A1 segment anterior cerebral artery (ACA) enhancement, and was prospectively identified by both radiologists as having undergone ACA thrombectomy due to embolism during MCA thrombectomy. Postcontrast T1-weighted vessel wall enhancement was detected in 0% of control patients. Our findings suggest that vessel wall injuries incurred during stent-retriever thrombectomy can be detected utilizing contrast-enhanced 3 T VW-MRI. Our results further demonstrate greater endothelial injury when the thrombectomy device is oversized relative to the

  14. Influence and Modeling of Residual Stresses in Thick Walled Pressure Vessels with Through Holes

    DTIC Science & Technology

    2012-02-28

    Technical Report ARWSB-TR-12003 INFLUENCE AND MODELING OF RESIDUAL STRESSES IN THICK WALLED PRESSURE VESSELS WITH...DATE (DD-MM-YYYY) 28/02/2012 2. REPORT TYPE Technical Report 3. DATES COVERED (From - To) 4. TITLE AND SUBTITLE Influence and Modeling of...Residual Stresses in Thick Walled Pressure Vessels with Through Holes 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT

  15. Correlating Hemodynamic Magnetic Resonance Imaging with high-field Intracranial Vessel Wall Imaging in Stroke

    PubMed Central

    Langdon, Weston; Donahue, Manus J.; van der Kolk, Anja G.; Rane, Swati; Strother, Megan K.

    2014-01-01

    Vessel wall magnetic resonance imaging at ultra-high field (7 Tesla) can be used to visualize vascular lesions noninvasively and holds potential for improving stroke-risk assessment in patients with ischemic cerebrovascular disease. We present the first multi-modal comparison of such high-field vessel wall imaging with more conventional (i) 3 Tesla hemodynamic magnetic resonance imaging and (ii) digital subtraction angiography in a 69-year-old male with a left temporal ischemic infarct. PMID:25426229

  16. Correlating hemodynamic magnetic resonance imaging with high-field intracranial vessel wall imaging in stroke.

    PubMed

    Langdon, Weston; Donahue, Manus J; van der Kolk, Anja G; Rane, Swati; Strother, Megan K

    2014-06-01

    Vessel wall magnetic resonance imaging at ultra-high field (7 Tesla) can be used to visualize vascular lesions noninvasively and holds potential for improving stroke-risk assessment in patients with ischemic cerebrovascular disease. We present the first multi-modal comparison of such high-field vessel wall imaging with more conventional (i) 3 Tesla hemodynamic magnetic resonance imaging and (ii) digital subtraction angiography in a 69-year-old male with a left temporal ischemic infarct.

  17. Evaluation of 3D multi-contrast joint intra- and extracranial vessel wall cardiovascular magnetic resonance.

    PubMed

    Zhou, Zechen; Li, Rui; Zhao, Xihai; He, Le; Wang, Xiaole; Wang, Jinnan; Balu, Niranjan; Yuan, Chun

    2015-05-27

    Multi-contrast vessel wall cardiovascular magnetic resonance (CMR) has demonstrated its capability for atherosclerotic plaque morphology measurement and component characterization in different vasculatures. However, limited coverage and partial volume effect with conventional two-dimensional (2D) techniques might cause lesion underestimation. The aim of this work is to evaluate the performance in a) blood suppression and b) vessel wall delineation of three-dimensional (3D) multi-contrast joint intra- and extracranial vessel wall imaging at 3T. Three multi-contrast 3D black blood (BB) sequences with T1, T2 and heavy T1 weighting and a custom designed 36-channel neurovascular coil covering the entire intra- and extracranial vasculature have been used and investigated in this study. Two healthy subjects were recruited for sequence parameter optimization and twenty-five patients were consecutively scanned for image quality and blood suppression assessment. Qualitative image scores of vessel wall delineation as well as quantitative Signal-to-Noise Ratio (SNR) and Contrast-to-Noise Ratio (CNR) were evaluated at five typical locations ranging from common carotid arteries to middle cerebral arteries. The 3D multi-contrast images acquired within 15mins allowed the vessel wall visualization with 0.8 mm isotropic spatial resolution covering intra- and extracranial segments. Quantitative wall and lumen SNR measurements for each sequence showed effective blood suppression at all selected locations (P < 0.0001). Although the wall-lumen CNR varied across measured locations, each sequence provided good or adequate image quality in both intra- and extracranial segments. The proposed 3D multi-contrast vessel wall technique provides isotropic resolution and time efficient solution for joint intra- and extracranial vessel wall CMR.

  18. Simulation of Diffusive Lithium Evaporation Onto the NSTX Vessel Walls

    SciTech Connect

    Stotler, D. P.; Skinner, C. H.; Blanchard, W. R.; Krstic, P. S.; Kugel, H. W.; Schneider, H.; Zakharov, L. E.

    2010-12-09

    A model for simulating the diffusive evaporation of lithium into a helium filled NSTX vacuum vessel is described and validated against an initial set of deposition experiments. The DEGAS 2 based model consists of a three-dimensional representation of the vacuum vessel, the elastic scattering process, and a kinetic description of the evaporated atoms. Additional assumptions are required to account for deuterium out-gassing during the validation experiments. The model agrees with the data over a range of pressures to within the estimated uncertainties. Suggestions are made for more discriminating experiments that will lead to an improved model.

  19. Optical coherence tomography assessment of vessel wall degradation in aneurysmatic thoracic aortas

    NASA Astrophysics Data System (ADS)

    Real, Eusebio; Eguizabal, Alma; Pontón, Alejandro; Val-Bernal, J. Fernando; Mayorga, Marta; Revuelta, José M.; López-Higuera, José; Conde, Olga M.

    2013-06-01

    Optical coherence tomographic images of ascending thoracic human aortas from aneurysms exhibit disorders on the smooth muscle cell structure of the media layer of the aortic vessel as well as elastin degradation. Ex-vivo measurements of human samples provide results that correlate with pathologist diagnosis in aneurysmatic and control aortas. The observed disorders are studied as possible hallmarks for aneurysm diagnosis. To this end, the backscattering profile along the vessel thickness has been evaluated by fitting its decay against two different models, a third order polynomial fitting and an exponential fitting. The discontinuities present on the vessel wall on aneurysmatic aortas are slightly better identified with the exponential approach. Aneurysmatic aortic walls present uneven reflectivity decay when compared with healthy vessels. The fitting error has revealed as the most favorable indicator for aneurysm diagnosis as it provides a measure of how uniform is the decay along the vessel thickness.

  20. Remodeling of blood vessels: responses of diameter and wall thickness to hemodynamic and metabolic stimuli.

    PubMed

    Pries, Axel R; Reglin, Bettina; Secomb, Timothy W

    2005-10-01

    Vascular functions, including tissue perfusion and peripheral resistance, reflect continuous structural adaptation (remodeling) of blood vessels in response to several stimuli. Here, a theoretical model is presented that relates the structural and functional properties of microvascular networks to the adaptive responses of individual segments to hemodynamic and metabolic stimuli. All vessels are assumed to respond, according to a common set of adaptation rules, to changes in wall shear stress, circumferential wall stress, and tissue metabolic status (indicated by partial pressure of oxygen). An increase in vessel diameter with increasing wall shear stress and an increase in wall mass with increased circumferential stress are needed to ensure stable vascular adaptation. The model allows quantitative predictions of the effects of changes in systemic hemodynamic conditions or local adaptation characteristics on vessel structure and on peripheral resistance. Predicted effects of driving pressure on the ratio of wall thickness to vessel diameter are consistent with experimental observations. In addition, peripheral resistance increases by approximately 65% for an increase in driving pressure from 50 to 150 mm Hg. Peripheral resistance is predicted to be markedly increased in response to a decrease in vascular sensitivity to wall shear stress, and to be decreased in response to increased tissue metabolic demand. This theoretical approach provides a framework for integrating available information on structural remodeling in the vascular system and predicting responses to changing conditions or altered vascular reactivity, as may occur in hypertension.

  1. Quantification and Statistical Analysis Methods for Vessel Wall Components from Stained Images with Masson's Trichrome

    PubMed Central

    Hernández-Morera, Pablo; Castaño-González, Irene; Travieso-González, Carlos M.; Mompeó-Corredera, Blanca; Ortega-Santana, Francisco

    2016-01-01

    Purpose To develop a digital image processing method to quantify structural components (smooth muscle fibers and extracellular matrix) in the vessel wall stained with Masson’s trichrome, and a statistical method suitable for small sample sizes to analyze the results previously obtained. Methods The quantification method comprises two stages. The pre-processing stage improves tissue image appearance and the vessel wall area is delimited. In the feature extraction stage, the vessel wall components are segmented by grouping pixels with a similar color. The area of each component is calculated by normalizing the number of pixels of each group by the vessel wall area. Statistical analyses are implemented by permutation tests, based on resampling without replacement from the set of the observed data to obtain a sampling distribution of an estimator. The implementation can be parallelized on a multicore machine to reduce execution time. Results The methods have been tested on 48 vessel wall samples of the internal saphenous vein stained with Masson’s trichrome. The results show that the segmented areas are consistent with the perception of a team of doctors and demonstrate good correlation between the expert judgments and the measured parameters for evaluating vessel wall changes. Conclusion The proposed methodology offers a powerful tool to quantify some components of the vessel wall. It is more objective, sensitive and accurate than the biochemical and qualitative methods traditionally used. The permutation tests are suitable statistical techniques to analyze the numerical measurements obtained when the underlying assumptions of the other statistical techniques are not met. PMID:26761643

  2. Assessing the performance of vessel wall tracking algorithms: the importance of the test phantom

    NASA Astrophysics Data System (ADS)

    Ramnarine, K. V.; Kanber, B.; Panerai, R. B.

    2004-01-01

    There is widespread clinical interest in assessing the mechanical properties of tissues and vessel walls. This study investigated the importance of the test phantom in providing a realistic assessment of clinical wall tracking performance for a variety of ultrasound modalities. B-mode, colour Doppler and Tissue Doppler Imaging (TDI) cineloop images were acquired using a Philips HDI5000 scanner and L12-5 probe. In-vivo longitudinal sections of 30 common carotid arteries and in-vitro images of pulsatile flow of a blood mimicking fluid through walled and wall-less tissue and vessel mimicking flow phantoms were analysed. Vessel wall tracking performance was assessed for our new probabilistic B-mode algorithm (PROBAL), and 3 different techniques implemented by Philips Medical Systems, based on B-mode edge detection (LDOT), colour Doppler (CVIQ) and TDI (TDIAWM). Precision (standard deviation/mean) of the peak systole dilations for respective PROBAL, LDOT, CVIQ and TDIAWM techniques were: 15.4 +/- 8.4%, 23 +/- 12.7%, 10 +/- 10% and 10.3 +/- 8.1% for the common carotid arteries; 6.4%, 22%, 11.6% and 34.5% for the wall-less flow phantom, 5.3%, 9.8%, 23.4% and 2.7% for the C-flex walled phantom and 3.9%, 2.6%, 1% and 3.2% for the latex walled phantom. The test phantom design and construction had a significant effect on the measurement of wall tracking performance.

  3. Segmentation of arterial vessel wall motion to sub-pixel resolution using M-mode ultrasound.

    PubMed

    Fancourt, Craig; Azer, Karim; Ramcharan, Sharmilee L; Bunzel, Michelle; Cambell, Barry R; Sachs, Jeffrey R; Walker, Matthew

    2008-01-01

    We describe a method for segmenting arterial vessel wall motion to sub-pixel resolution, using the returns from M-mode ultrasound. The technique involves measuring the spatial offset between all pairs of scans from their cross-correlation, converting the spatial offsets to relative wall motion through a global optimization, and finally translating from relative to absolute wall motion by interpolation over the M-mode image. The resulting detailed wall distension waveform has the potential to enhance existing vascular biomarkers, such as strain and compliance, as well as enable new ones.

  4. Use of a hand-held Doppler to avoid abdominal wall vessels in laparoscopic surgery.

    PubMed Central

    Whiteley, M. S.; Laws, S. A.; Wise, M. H.

    1994-01-01

    Laparoscopy in general surgery is becoming a wide-spread technique. Substantial anterior abdominal wall haemorrhage is a recognised complication of the laparoscopic technique. Ten patients were examined with an 8 MHz hand-held Doppler and the anterior abdominal wall vessels were marked on the skin. Colour flow duplex was used to confirm the presence of vessels found in this way. All 40 epigastric arteries were marked accurately and confirmed; 75 other intramural arteries were identified, although the majority were too small for duplex confirmation. The preoperative use of hand-held Doppler is a quick and non-invasive way to identify the epigastric and larger intramural arteries. Routine use of this technique to mark abdominal wall vessels in the areas of trocar insertion should reduce this complication of laparoscopic surgery. PMID:7661918

  5. Numerical simulation of hydrogen diffusion in the pressure vessel wall of a WWER-440 reactor

    NASA Astrophysics Data System (ADS)

    Toribio, J.; Vergara, D.; Lorenzo, M.

    2017-07-01

    Materials forming the wall of a nuclear reactor pressure vessel (NRPV) can undergo in-service failure due to the presence of hydrogen, which enhances the fracture process known as hydrogen embrittlement (HE). A common way of avoiding this damage phenomenon is using a cladding material at the vessel wall side exposed to the hydrogenating source. This layer acts as a barrier for hydrogen diffusion and, hence, it protects the base material. In this paper, a numerical model of hydrogen diffusion assisted by stress and strain is used to analyse the hydrogen distribution, and hence the HE, in the pressure vessel wall of a real widely spread WWER-440 reactor considering two thickness for the cladding layer. Results show how the hydrogen accumulation is delayed as the thickness of the cladding layer increases, thus delaying the HE phenomenon affecting the structural integrity of the reactor.

  6. Construction of 3-Dimensional Printed Ultrasound Phantoms With Wall-less Vessels.

    PubMed

    Nikitichev, Daniil I; Barburas, Anamaria; McPherson, Kirstie; Mari, Jean-Martial; West, Simeon J; Desjardins, Adrien E

    2016-06-01

    Ultrasound phantoms are invaluable as training tools for vascular access procedures. We developed ultrasound phantoms with wall-less vessels using 3-dimensional printed chambers. Agar was used as a soft tissue-mimicking material, and the wall-less vessels were created with rods that were retracted after the agar was set. The chambers had integrated luer connectors to allow for fluid injections with clinical syringes. Several variations on this design are presented, which include branched and stenotic vessels. The results show that 3-dimensional printing can be well suited to the construction of wall-less ultrasound phantoms, with designs that can be readily customized and shared electronically. © 2016 by the American Institute of Ultrasound in Medicine.

  7. Revisiting tumor angiogenesis: vessel co-option, vessel remodeling, and cancer cell-derived vasculature formation.

    PubMed

    Qian, Chao-Nan; Tan, Min-Han; Yang, Jun-Ping; Cao, Yun

    2016-01-08

    Tumor growth and metastasis depend on the establishment of tumor vasculature to provide oxygen, nutrients, and other essential factors. The well-known vascular endothelial growth factor (VEGF) signaling is crucial for sprouting angiogenesis as well as recruitment of circulating progenitor endothelial cells to tumor vasculature, which has become therapeutic targets in clinical practice. However, the survival benefits gained from targeting VEGF signaling have been very limited, with the inevitable development of treatment resistance. In this article, we discuss the most recent findings and understanding on how solid tumors evade VEGF-targeted therapy, with a special focus on vessel co-option, vessel remodeling, and tumor cell-derived vasculature establishment. Vessel co-option may occur in tumors independently of sprouting angiogenesis, and sprouting angiogenesis is not always required for tumor growth. The differences between vessel-like structure and tubule-like structure formed by tumor cells are also introduced. The exploration of the underlying mechanisms of these alternative angiogenic approaches would not only widen our knowledge of tumor angiogenesis but also provide novel therapeutic targets for better controlling cancer growth and metastasis.

  8. Joint blood and cerebrospinal fluid suppression for intracranial vessel wall MRI.

    PubMed

    Wang, Jinnan; Helle, Michael; Zhou, Zechen; Börnert, Peter; Hatsukami, Thomas S; Yuan, Chun

    2016-02-01

    To develop and evaluate a joint blood and cerebrospinal fluid (CSF) suppression technique for improved intracranial vessel wall MR imaging. The Delay Alternating with Nutation for Tailored Excitation (DANTE) prepulse was specifically optimized for CSF suppression to improve vessel wall and CSF contrast. It was evaluated on six patients and three healthy volunteers. CSF suppression efficiency, lumen signal to noise ratio, and wall-lumen contrast to noise ratio were compared between images with and without DANTE in major intercranial artery segments. Contrast changes in tissues were also compared with evaluate the technique's compatibility with multicontrast imaging techniques. The optimized DANTE images significantly improved intracranial vessel wall characterization on all images. Quantitatively, CSF to wall contrast improved by 28% (DANTE-VISTA 1.354 ± 0.216 versus VISTA 1.057 ± 0.13; P < 0.001). DANTE also significantly improved wall-lumen (10.55 ± 3.79 versus 9.34 ± 3.54; P < 0.001) and wall-CSF (4.62 ± 3.19 versus 0.78 ± 2.30; P < 0.001) contrast-to-noise ratios. DANTE prepared images were also found to make only minimal impact on static tissue contrast. DANTE prepared MR imaging can significantly improve contrast between the vessel wall and cerebral spinal fluid in major intracranial arteries, holding a good potential to be combined with multicontrast protocol for intracranial wall imaging. © 2015 Wiley Periodicals, Inc.

  9. Could the heat sink effect of blood flow inside large vessels protect the vessel wall from thermal damage during RF-assisted surgical resection?

    PubMed

    González-Suárez, Ana; Trujillo, Macarena; Burdío, Fernando; Andaluz, Anna; Berjano, Enrique

    2014-08-01

    To assess by means of computer simulations whether the heat sink effect inside a large vessel (portal vein) could protect the vessel wall from thermal damage close to an internally cooled electrode during radiofrequency (RF)-assisted resection. First,in vivo experiments were conducted to validate the computational model by comparing the experimental and computational thermal lesion shapes created around the vessels. Computer simulations were then carried out to study the effect of different factors such as device-tissue contact, vessel position, and vessel-device distance on temperature distributions and thermal lesion shapes near a large vessel, specifically the portal vein. The geometries of thermal lesions around the vessels in the in vivo experiments were in agreement with the computer results. The thermal lesion shape created around the portal vein was significantly modified by the heat sink effect in all the cases considered. Thermal damage to the portal vein wall was inversely related to the vessel-device distance. It was also more pronounced when the device-tissue contact surface was reduced or when the vessel was parallel to the device or perpendicular to its distal end (blade zone), the vessel wall being damaged at distances less than 4.25 mm. The computational findings suggest that the heat sink effect could protect the portal vein wall for distances equal to or greater than 5 mm, regardless of its position and distance with respect to the RF-based device.

  10. Automated Delineation of Vessel Wall and Thrombus Boundaries of Abdominal Aortic Aneurysms Using Multispectral MR Images

    PubMed Central

    Rodriguez-Vila, B.; Tarjuelo-Gutierrez, J.; Sánchez-González, P.; Verbrugghe, P.; Fourneau, I.; Maleux, G.; Herijgers, P.; Gomez, E. J.

    2015-01-01

    A correct patient-specific identification of the abdominal aortic aneurysm is useful for both diagnosis and treatment stages, as it locates the disease and represents its geometry. The actual thickness and shape of the arterial wall and the intraluminal thrombus are of great importance when predicting the rupture of the abdominal aortic aneurysms. The authors describe a novel method for delineating both the internal and external contours of the aortic wall, which allows distinguishing between vessel wall and intraluminal thrombus. The method is based on active shape model and texture statistical information. The method was validated with eight MR patient studies. There was high correspondence between automatic and manual measurements for the vessel wall area. Resulting segmented images presented a mean Dice coefficient with respect to manual segmentations of 0.88 and a mean modified Hausdorff distance of 1.14 mm for the internal face and 0.86 and 1.33 mm for the external face of the arterial wall. Preliminary results of the segmentation show high correspondence between automatic and manual measurements for the vessel wall and thrombus areas. However, since the dataset is small the conclusions cannot be generalized. PMID:26236390

  11. Vessel wall magnetic resonance imaging in acute ischemic stroke: effects of embolism and mechanical thrombectomy on the arterial wall.

    PubMed

    Power, Sarah; Matouk, Charles; Casaubon, Leanne K; Silver, Frank L; Krings, Timo; Mikulis, David J; Mandell, Daniel M

    2014-08-01

    The aim of the study was to determine the effects of thromboembolism and mechanical thrombectomy on the vessel wall magnetic resonance imaging (VW-MRI) appearance of the intracranial arterial wall. This was a cross-sectional study of consecutive patients with acute intracranial arterial occlusion who underwent high-resolution contrast-enhanced VW-MRI within days of stroke presentation. For each patient, we categorized arterial wall thickening and enhancement as definite, possible, or none using contralateral arteries as a reference standard. We performed χ(2) tests to compare the effects of medical therapy and mechanical thrombectomy. Sixteen patients satisfied inclusion criteria. Median time from symptom onset to VW-MRI was 3 days (interquartile range, 2 days). Among 6 patients treated with mechanical thrombectomy using a stent retriever, VW-MRI demonstrated definite arterial wall thickening in 5 (83%) and possible thickening in 1 (17%); there was definite wall enhancement in 4 (67%) and possible enhancement in 2 (33%). Among 10 patients treated with medical therapy alone, VW-MRI demonstrated definite arterial wall thickening in 3 (30%) and possible thickening in 2 (20%); there was definite wall enhancement in 2 (20%) and possible enhancement in 2 (20%). Arterial wall thickening and enhancement were more common in patients treated with mechanical thrombectomy than with medical therapy alone (P=0.037 and P=0.016, respectively). Mechanical thrombectomy results in intracranial arterial wall thickening and enhancement, potentially mimicking the VW-MRI appearance of primary arteritis. This arterial wall abnormality is less common in patients with arterial occlusion who have been treated with medical therapy alone. © 2014 American Heart Association, Inc.

  12. Effects of X-irradiation on artificial blood vessel wall degradation by invasive tumor cells

    SciTech Connect

    Heisel, M.A.; Laug, W.E.; Stowe, S.M.; Jones, P.A.

    1984-06-01

    Artificial vessel wall cultures, constructed by growing arterial endothelial cells on preformed layers of rat smooth muscle cells, were used to evaluate the effects of X-irradiation on tumor cell-induced tissue degradation. Bovine endothelial cells had radiation sensitivities similar to those of rat smooth muscle cells. Preirradiation of smooth muscle cells, before the addition of human fibrosarcoma (HT 1080) cells, did not increase the rate of degradation and destruction by the invasive cells. However, the degradation rate was decreased if the cultures were irradiated after the addition of HT 1080 cells. The presence of bovine endothelial cells markedly inhibited the destructive abilities of fibrosarcoma cells, but preirradiation of artificial vessel walls substantially decreased their capabilities to resist HT 1080-induced lysis. These findings suggest that the abilities of blood vessels to limit extravasation may be compromised by ionizing radiation.

  13. Role of Outgassing of ITER Vacuum Vessel In-Wall Shielding Materials in Leak Detection of ITER Vacuum Vessel

    NASA Astrophysics Data System (ADS)

    Maheshwari, A.; Pathak, H. A.; Mehta, B. K.; Phull, G. S.; Laad, R.; Shaikh, M. S.; George, S.; Joshi, K.; Khan, Z.

    2017-04-01

    ITER Vacuum Vessel is a torus-shaped, double wall structure. The space between the double walls of the VV is filled with In-Wall Shielding Blocks (IWS) and Water. The main purpose of IWS is to provide neutron shielding during ITER plasma operation and to reduce ripple of Toroidal Magnetic Field (TF). Although In-Wall Shield Blocks (IWS) will be submerged in water in between the walls of the ITER Vacuum Vessel (VV), Outgassing Rate (OGR) of IWS materials plays a significant role in leak detection of Vacuum Vessel of ITER. Thermal Outgassing Rate of a material critically depends on the Surface Roughness of material. During leak detection process using RGA equipped Leak detector and tracer gas Helium, there will be a spill over of mass 3 and mass 2 to mass 4 which creates a background reading. Helium background will have contribution of Hydrogen too. So it is necessary to ensure the low OGR of Hydrogen. To achieve an effective leak test it is required to obtain a background below 1 × 10-8 mbar 1 s-1 and hence the maximum Outgassing rate of IWS Materials should comply with the maximum Outgassing rate required for hydrogen i.e. 1 x 10-10 mbar 1 s-1 cm-2 at room temperature. As IWS Materials are special materials developed for ITER project, it is necessary to ensure the compliance of Outgassing rate with the requirement. There is a possibility of diffusing the gasses in material at the time of production. So, to validate the production process of materials as well as manufacturing of final product from this material, three coupons of each IWS material have been manufactured with the same technique which is being used in manufacturing of IWS blocks. Manufacturing records of these coupons have been approved by ITER-IO (International Organization). Outgassing rates of these coupons have been measured at room temperature and found in acceptable limit to obtain the required Helium Background. On the basis of these measurements, test reports have been generated and got

  14. Compressed sensing based simultaneous black- and gray-blood carotid vessel wall MR imaging.

    PubMed

    Li, Bo; Li, Hao; Kong, Hanjing; Dong, Li; Zhang, Jue; Fang, Jing

    2017-05-01

    In this study, we sought to demonstrate the blood suppression performance, image quality and morphological measurements for compressed sensing (CS) based simultaneous 3D black- and gray-blood imaging sequence (CS-siBLAG) in carotid vessel wall MR imaging. Seven healthy volunteers and five patients were recruited. Healthy subjects underwent five CS-siBLAG scans with 1, 2, 3, 4 and 5-fold accelerations. Signal-to-tissue ratio (STR) and contrast-to-tissue ratio (CTR) were computed as the measures of flowing signal suppression performance and the image quality for black-blood imaging of the technique. Vessel lumen area (LA) and wall area (WA) were compared between fully sampled acquisition and each accelerated acquisition. Patients underwent three CS-siBLAG scans with 1, 3 and 5-fold accelerations as well as a 3D time of flight (3D TOF) scan. Two radiologists reviewed the under-sampled black- and gray-blood image quality. STR and CTR values obtained with 2 to 5-fold accelerations were not significantly different from those with full acquisition. LA and WA measured at 2×, 3×, 4× and 5× were all highly correlated to the corresponding values at 1×. For patients imaging, two radiologists both found that the dual-contrast images at 3× acceleration exhibited comparable image quality to that of the fully sampled acquisition, and that the images at 5× exhibited slightly blurred vessel wall and outer vessel wall boundaries. By combining the CS under-sampling pattern and reconstruction, pseudo-centric phase encoding order and dual blood contrast sequences, this technique provides spatially registered black- and gray-blood images and excellent visualization for vessel wall imaging and gray-blood imaging in a short scan time. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. The analysis and diagnosis of unstable behavior of the blood vessel wall with an aneurysm based on noise science.

    PubMed

    Yokobori, A Toshimitsu; Owa, Michiaki; Ichiki, Masataka; Satoh, Tomoki; Ohtomo, Yuji; Satoh, Yusuke; Ohgoshi, Seiichi; Kinoshita, Yoshihiko; Karino, Shinichi

    2006-08-01

    Previously, one of the authors developed a noninvasive measurement method of acceleration and deceleration during the expansion process of the blood vessel wall under pulsatile pressure flow by measuring the strain rate of the blood vessel wall using a supersonic Doppler effect sensor aided by computer analysis (DPC method). In this paper, on the basis of the analysis of chaos theory, that is, the complexity of science, the unstable behavior of the blood vessel wall with an aneurysm was investigated by identifying the characteristic DPC wave forms induced by the onset and progression of aneurysm. These results showed that unstable dynamic behavior of the blood vessel wall occurs due to the progression of the aneurysm. Furthermore, using the theoretical analysis of chaos, this unstable behavior of the blood vessel wall was quantified and the fundamental principle of a noninvasive diagnostic method of the progressive degree of aneurysm was proposed.

  16. Evaluation of side effects of radiofrequency capacitive hyperthermia with magnetite on the blood vessel walls of tumor metastatic lesion surrounding the abdominal large vessels: an agar phantom study

    PubMed Central

    2014-01-01

    Background Magnetite used in an 8-MHz radiofrequency (RF) capacitive heating device can increase the temperature of a specific site up to 45°C. When treating a metastatic lesion around large abdominal vessels via hyperthermia with magnetite, heating-induced adverse effects on these vessels need to be considered. Therefore, this study examined hyperthermia-induced damage to blood vessel walls in vitro. Methods A large agar phantom with a circulatory system consisting of a swine artery and vein connected to a peristaltic pump was prepared. The blood vessels were placed on the magnetite-containing agar piece. Heating was continued for 30 min at 45°C. After heating, a histological study for injury to the blood vessels was performed. Results The inner membrane temperature did not reach 45°C due to the cooling effect of the blood flow. In the heated vessels, vascular wall collagen degenerated and smooth muscle cells were narrowed; however, no serious changes were noted in the vascular endothelial cells or vascular wall elastic fibers. The heated vessel wall was not severely damaged; this was attributed to cooling by the blood flow. Conclusions Our findings indicate that RF capacitive heating therapy with magnetite may be used for metastatic lesions without injuring the surrounding large abdominal vessels. PMID:25114787

  17. Protective interior wall and attach8ing means for a fusion reactor vacuum vessel

    DOEpatents

    Phelps, Richard D.; Upham, Gerald A.; Anderson, Paul M.

    1988-01-01

    An array of connected plates mounted on the inside wall of the vacuum vessel of a magnetic confinement reactor in order to provide a protective surface for energy deposition inside the vessel. All fasteners are concealed and protected beneath the plates, while the plates themselves share common mounting points. The entire array is installed with torqued nuts on threaded studs; provision also exists for thermal expansion by mounting each plate with two of its four mounts captured in an oversize grooved spool. A spool-washer mounting hardware allows one edge of a protective plate to be torqued while the other side remains loose, by simply inverting the spool-washer hardware.

  18. JSC technician checks STS-44 DSO 316 bioreactor and rotating wall vessel hdwr

    NASA Image and Video Library

    1991-06-27

    S91-40049 (27 June 1991) --- JSC technician Tacey Prewitt checks the progress on a bioreactor experiment in JSC's Life Sciences Laboratory Bldg 37 biotechnology laboratory. Similar hardware is scheduled for testing aboard Atlantis, Orbiter Vehicle (OV) 104, during STS-44. Detailed Supplementary Objective (DSO) 316 Bioreactor/Flow and Particle Trajectory in Microgravity will checkout the rotating wall vessel hardware and hopefully will confirm researchers' theories and calculations about how flow fields work in space. Plastic beads of various sizes rather than cell cultures are being flown in the vessel for the STS-44 test.

  19. JSC technician checks STS-44 DSO 316 bioreactor and rotating wall vessel hdwr

    NASA Technical Reports Server (NTRS)

    1991-01-01

    JSC technician Tacey Prewitt checks the progress on a bioreactor experiment in JSC's Life Sciences Laboratory Bldg 37 biotechnology laboratory. Similar hardware is scheduled for testing aboard Atlantis, Orbiter Vehicle (OV) 104, during STS-44. Detailed Supplementary Objective (DSO) 316 Bioreactor/Flow and Particle Trajectory in Microgravity will checkout the rotating wall vessel hardware and hopefully will confirm researchers' theories and calculations about how flow fields work in space. Plastic beads of various sizes rather than cell cultures are being flown in the vessel for the STS-44 test.

  20. Effects of dynamic shear and transmural pressure on wall shear stress sensitivity in collecting lymphatic vessels.

    PubMed

    Kornuta, Jeffrey A; Nepiyushchikh, Zhanna; Gasheva, Olga Y; Mukherjee, Anish; Zawieja, David C; Dixon, J Brandon

    2015-11-01

    Given the known mechanosensitivity of the lymphatic vasculature, we sought to investigate the effects of dynamic wall shear stress (WSS) on collecting lymphatic vessels while controlling for transmural pressure. Using a previously developed ex vivo lymphatic perfusion system (ELPS) capable of independently controlling both transaxial pressure gradient and average transmural pressure on an isolated lymphatic vessel, we imposed a multitude of flow conditions on rat thoracic ducts, while controlling for transmural pressure and measuring diameter changes. By gradually increasing the imposed flow through a vessel, we determined the WSS at which the vessel first shows sign of contraction inhibition, defining this point as the shear stress sensitivity of the vessel. The shear stress threshold that triggered a contractile response was significantly greater at a transmural pressure of 5 cmH2O (0.97 dyne/cm(2)) than at 3 cmH2O (0.64 dyne/cm(2)). While contraction frequency was reduced when a steady WSS was applied, this inhibition was reversed when the applied WSS oscillated, even though the mean wall shear stresses between the conditions were not significantly different. When the applied oscillatory WSS was large enough, flow itself synchronized the lymphatic contractions to the exact frequency of the applied waveform. Both transmural pressure and the rate of change of WSS have significant impacts on the contractile response of lymphatic vessels to flow. Specifically, time-varying shear stress can alter the inhibition of phasic contraction frequency and even coordinate contractions, providing evidence that dynamic shear could play an important role in the contractile function of collecting lymphatic vessels. Copyright © 2015 the American Physiological Society.

  1. Effects of dynamic shear and transmural pressure on wall shear stress sensitivity in collecting lymphatic vessels

    PubMed Central

    Kornuta, Jeffrey A.; Nepiyushchikh, Zhanna; Gasheva, Olga Y.; Mukherjee, Anish; Zawieja, David C.

    2015-01-01

    Given the known mechanosensitivity of the lymphatic vasculature, we sought to investigate the effects of dynamic wall shear stress (WSS) on collecting lymphatic vessels while controlling for transmural pressure. Using a previously developed ex vivo lymphatic perfusion system (ELPS) capable of independently controlling both transaxial pressure gradient and average transmural pressure on an isolated lymphatic vessel, we imposed a multitude of flow conditions on rat thoracic ducts, while controlling for transmural pressure and measuring diameter changes. By gradually increasing the imposed flow through a vessel, we determined the WSS at which the vessel first shows sign of contraction inhibition, defining this point as the shear stress sensitivity of the vessel. The shear stress threshold that triggered a contractile response was significantly greater at a transmural pressure of 5 cmH2O (0.97 dyne/cm2) than at 3 cmH2O (0.64 dyne/cm2). While contraction frequency was reduced when a steady WSS was applied, this inhibition was reversed when the applied WSS oscillated, even though the mean wall shear stresses between the conditions were not significantly different. When the applied oscillatory WSS was large enough, flow itself synchronized the lymphatic contractions to the exact frequency of the applied waveform. Both transmural pressure and the rate of change of WSS have significant impacts on the contractile response of lymphatic vessels to flow. Specifically, time-varying shear stress can alter the inhibition of phasic contraction frequency and even coordinate contractions, providing evidence that dynamic shear could play an important role in the contractile function of collecting lymphatic vessels. PMID:26333787

  2. Detecting Intracranial Vessel Wall Lesions With 7T-Magnetic Resonance Imaging: Patients With Posterior Circulation Ischemia Versus Healthy Controls.

    PubMed

    Harteveld, Anita A; van der Kolk, Anja G; van der Worp, H Bart; Dieleman, Nikki; Zwanenburg, Jaco J M; Luijten, Peter R; Hendrikse, Jeroen

    2017-09-01

    Vessel wall magnetic resonance imaging sequences have been developed to directly visualize the intracranial vessel wall, enabling detection of vessel wall changes, including those that have not yet caused luminal narrowing. In this study, vessel wall lesion burden was assessed in patients with recent posterior circulation ischemia using 7T-magnetic resonance imaging and compared with matched healthy controls. Fifty subjects (25 patients and 25 matched healthy controls) underwent 7T-magnetic resonance imaging with an intracranial vessel wall sequence before and after contrast administration. Two raters scored the presence and contrast enhancement of arterial wall lesions in individual segments of the circle of Willis and its primary branches. Total burden and distribution of vessel wall lesions and lesion characteristics (configuration, thickening pattern, and contrast enhancement) were compared both between and within both groups. Overall, vessel wall lesion burden and distribution were comparable between patients and controls. Regarding individual arterial segments, only vessel wall lesions in the posterior cerebral artery were more frequently observed in patients (18.0%) than in controls (5.4%; P=0.003). Many of these lesions showed enhancement, both in patients (48.9%) and in controls (43.5%; P=0.41). In patients, the proportion of enhancing lesions was higher in the posterior circulation (53.3%) than in the anterior circulation (20.6%; P=0.008). Although overall intracranial vessel wall lesion burden and contrast enhancement were comparable between patients with recent posterior circulation ischemia and healthy controls, this study also revealed significant differences between the 2 groups, suggesting an association between posterior circulation lesion burden/enhancement and ischemic events. URL: http://www.trialregister.nl. Unique identifier: NTR5688. © 2017 American Heart Association, Inc.

  3. Influence of acquired obesity on coronary vessel wall late gadolinium enhancement in discordant monozygote twins.

    PubMed

    Makowski, Marcus R; Jansen, Christian H P; Ebersberger, Ullrich; Schaeffter, Tobias; Razavi, Reza; Mangino, Massimo; Spector, Tim D; Botnar, Rene M; Greil, Gerald F

    2016-10-14

    The aim of this study was to investigate the impact of BMI on late gadolinium enhancement (LGE) of the coronary artery wall in identical monozygous twins discordant for BMI. Coronary LGE represents a useful parameter for the detection and quantification of atherosclerotic coronary vessel wall disease. Thirteen monozygote female twin pairs (n = 26) with significantly different BMIs (>1.6 kg/m2) were recruited out of >10,000 twin pairs (TwinsUK Registry). A coronary 3D-T2prep-TFE MR angiogram and 3D-IR-TFE vessel wall scan were performed prior to and following the administration of 0.2 mmol/kg of Gd-DTPA on a 1.5 T MR scanner. The number of enhancing coronary segments and contrast to noise ratios (CNRs) of the coronary wall were quantified. An increase in BMI was associated with an increased number of enhancing coronary segments (5.3 ± 1.5 vs. 3.5 ± 1.6, p < 0.0001) and increased coronary wall enhancement (6.1 ± 1.1 vs. 4.8 ± 0.9, p = 0.0027) compared to matched twins with lower BMI. This study in monozygous twins indicates that acquired factors predisposing to obesity, including lifestyle and environmental factors, result in increased LGE of the coronary arteries, potentially reflecting an increase in coronary atherosclerosis in this female study population. • BMI-discordant twins allow the investigation of the influence of lifestyle factors independent from genetic confounders. • Only thirteen obesity-discordant twins were identified underlining the strong genetic component of BMI. • In female twins, a BMI increase is associated with increased coronary late gadolinium enhancement. • Increased late gadolinium enhancement in the coronary vessel wall potentially reflects increased atherosclerosis.

  4. Vessel wall temperature estimation for novel short term thermal balloon angioplasty: study of thermal environment.

    PubMed

    Kaneko, Kenji; Nakatani, Eriko; Futami, Hikaru; Ogawa, Yoshifumi; Arai, Tsunenori; Fukui, Masaru; Shimamura, Satoshi; Kawabata, Takashi

    2005-01-01

    We have been proposing novel thermal balloon angioplasty, photo-thermo dynamic balloon angioplasty (PT-DBA). PTDBA realized <10s short term heating that can prevent surrounding tissue thermal injury and low pressure dilatation that can prevent restenosis in chronic phase. We aim to determine the most efficient heating condition suit to individual symptom with pre-operation thermal simulation. We analyzed the flow dynamics and heat convection inside the balloon, and investigated heat conduction of balloon film to establish the temperature estimation method among vessel wall. Compared with ex vivo temperature measurement experiment, we concluded that the factors need to be considered for the establishment would be the heat conduction of the flow inside PTDB, heat conduction at the balloon film, and contact thermal resistance between the balloon film and vessel wall.

  5. Regional calcium distribution and ultrasound images of the vessel wall in human carotid arteries

    NASA Astrophysics Data System (ADS)

    Szikszai, Z.; Kertész, Zs.; Uzonyi, I.; Szíki, G. Á.; Magyar, M. T.; Molnár, S.; Ida, Y.; Csiba, L.

    2005-04-01

    Arterial calcification can take place at two sites in the vessel wall: the intima and the media. Intimal calcification occurs exclusively within atherosclerotic plaques, while medial calcification may develop independently. Extensive calcified plaques in the carotid arteries can be easily detected by B-mode ultrasonic imaging. The calcium content might correlate with the ultrasound reflectance of the vessel wall, and could be a surrogate marker for arteriosclerosis. In this study, segments of human carotid arteries collected at autopsy were examined by ultrasonography in vitro and calcium distributional maps of sections from the same segments were determined by particle induced X-ray emission. Our aim was to make a first step towards investigating the relationship between the calcium distributional maps and the respective ultrasound images.

  6. Intracranial vessel wall imaging for evaluation of steno-occlusive diseases and intracranial aneurysms.

    PubMed

    Brinjikji, Waleed; Mossa-Basha, Mahmud; Huston, John; Rabinstein, Alejandro A; Lanzino, Giuseppe; Lehman, Vance T

    2017-03-01

    Cerebrovascular diseases have traditionally been classified, diagnosed and managed based on their luminal characteristics. However, over the past several years, several advancements in MRI techniques have ushered in high-resolution vessel wall imaging (HR-VWI), enabling evaluation of intracranial vessel wall pathology. These advancements now allow us to differentiate diseases which have a common angiographic appearance but vastly different natural histories (i.e. moyamoya versus atherosclerosis, reversible cerebral vasoconstriction syndrome versus vasculitis, stable versus unstable intracranial aneurysms). In this review, we detail the anatomical, histopathological and imaging characteristics of various intracranial steno-occlusive diseases and types of intracranial aneurysms and describe the role that HR-VWI can play in diagnosis, risk stratification and treatment.

  7. Nonstenotic Culprit Plaque: The Utility of High-Resolution Vessel Wall MRI of Intracranial Vessels after Ischemic Stroke

    PubMed Central

    de Havenon, Adam; Yuan, Chun; Tirschwell, David; Hatsukami, Thomas; Anzai, Yoshimi; Becker, Kyra; Sultan-Qurraie, Ali; Mossa-Basha, Mahmud

    2015-01-01

    Intracranial atherosclerotic disease (ICAD) accounts for 9–15% of ischemic stroke in the United States. Although highly stenotic ICAD accounts for most of the strokes, it is assumed that nonstenotic ICAD (nICAD) can result in stroke, despite being missed on standard luminal imaging modalities. We describe a patient with nICAD who suffered recurrent thromboembolic stroke and TIA but had a negative conventional stroke workup. As a result, they were referred for high-resolution magnetic resonance imaging (HR-MRI) of the arterial vessel wall, which identified a nonstenotic plaque with multiple high-risk features, identifying it as the etiology of the patient's thromboembolic events. The diagnosis resulted in a transition from anticoagulation to antiplatelet therapy, after which the patient's clinical events resolved. HR-MRI is an imaging technique that has the potential to guide medical management for patients with ischemic stroke, particularly in cryptogenic stroke. PMID:26346855

  8. Stress analysis of a double-wall vacuum vessel for ITER

    SciTech Connect

    Conner, D.L.; Williamson, D.E.; Nelson, B.E.

    1991-01-01

    The preliminary structural analyses performed in support of the design of the vacuum vessel for the International Thermonuclear Experimental Reactor (ITER) are described. A thin, double-wall, all-welded structure is the proposed design concept analyzed. The results of the static stress analysis indicate the adequacy of such a structure. The effects of the proposed high-aspect-ratio design configuration on loading and stresses are also discussed. 4 refs., 6 figs., 1 tab.

  9. Gadolinium Enhanced MR Coronary Vessel Wall Imaging at 3.0 Tesla.

    PubMed

    Kelle, Sebastian; Schlendorf, Kelly; Hirsch, Glenn A; Gerstenblith, Gary; Fleck, Eckart; Weiss, Robert G; Stuber, Matthias

    2010-10-11

    Purpose. We evaluated the influence of the time between low-dose gadolinium (Gd) contrast administration and coronary vessel wall enhancement (LGE) detected by 3T magnetic resonance imaging (MRI) in healthy subjects and patients with coronary artery disease (CAD). Materials and Methods. Four healthy subjects (4 men, mean age 29 ± 3 years and eleven CAD patients (6 women, mean age 61 ± 10 years) were studied on a commercial 3.0 Tesla (T) whole-body MR imaging system (Achieva 3.0 T; Philips, Best, The Netherlands). T1-weighted inversion-recovery coronary magnetic resonance imaging (MRI) was repeated up to 75 minutes after administration of low-dose Gadolinium (Gd) (0.1 mmol/kg Gd-DTPA). Results. LGE was seen in none of the healthy subjects, however in all of the CAD patients. In CAD patients, fifty-six of 62 (90.3%) segments showed LGE of the coronary artery vessel wall at time-interval 1 after contrast. At time-interval 2, 34 of 42 (81.0%) and at time-interval 3, 29 of 39 evaluable segments (74.4%) were enhanced. Conclusion. In this work, we demonstrate LGE of the coronary artery vessel wall using 3.0 T MRI after a single, low-dose Gd contrast injection in CAD patients but not in healthy subjects. In the majority of the evaluated coronary segments in CAD patients, LGE of the coronary vessel wall was already detectable 30-45 minutes after administration of the contrast agent.

  10. Natural history of mesenchymal stem cells, from vessel walls to culture vessels.

    PubMed

    Murray, Iain R; West, Christopher C; Hardy, Winters R; James, Aaron W; Park, Tea Soon; Nguyen, Alan; Tawonsawatruk, Tulyapruek; Lazzari, Lorenza; Soo, Chia; Péault, Bruno

    2014-04-01

    Mesenchymal stem/stromal cells (MSCs) can regenerate tissues by direct differentiation or indirectly by stimulating angiogenesis, limiting inflammation, and recruiting tissue-specific progenitor cells. MSCs emerge and multiply in long-term cultures of total cells from the bone marrow or multiple other organs. Such a derivation in vitro is simple and convenient, hence popular, but has long precluded understanding of the native identity, tissue distribution, frequency, and natural role of MSCs, which have been defined and validated exclusively in terms of surface marker expression and developmental potential in culture into bone, cartilage, and fat. Such simple, widely accepted criteria uniformly typify MSCs, even though some differences in potential exist, depending on tissue sources. Combined immunohistochemistry, flow cytometry, and cell culture have allowed tracking the artifactual cultured mesenchymal stem/stromal cells back to perivascular anatomical regions. Presently, both pericytes enveloping microvessels and adventitial cells surrounding larger arteries and veins have been described as possible MSC forerunners. While such a vascular association would explain why MSCs have been isolated from virtually all tissues tested, the origin of the MSCs grown from umbilical cord blood remains unknown. In fact, most aspects of the biology of perivascular MSCs are still obscure, from the emergence of these cells in the embryo to the molecular control of their activity in adult tissues. Such dark areas have not compromised intents to use these cells in clinical settings though, in which purified perivascular cells already exhibit decisive advantages over conventional MSCs, including purity, thorough characterization and, principally, total independence from in vitro culture. A growing body of experimental data is currently paving the way to the medical usage of autologous sorted perivascular cells for indications in which MSCs have been previously contemplated or

  11. Arabidopsis NAC Domain Proteins, VND1 to VND5, Are Transcriptional Regulators of Secondary Wall Biosynthesis in Vessels

    PubMed Central

    Zhou, Jianli; Zhong, Ruiqin; Ye, Zheng-Hua

    2014-01-01

    One of the most prominent features of xylem conducting cells is the deposition of secondary walls. In Arabidopsis, secondary wall biosynthesis in the xylem conducting cells, vessels, has been shown to be regulated by two VASCULAR-RELATED NAC-DOMAIN (VND) genes, VND6 and VND7. In this report, we have investigated the roles of five additional Arabidopsis VND genes, VND1 to VND5, in regulating secondary wall biosynthesis in vessels. The VND1 to VND5 genes were shown to be specifically expressed in vessels but not in interfascicular fibers in stems. The expression of VND4 and VND5 was also seen specifically in vessels in the secondary xylem of the root-hypocotyl region. When overexpressed, VND1 to VND5 were able to activate the expression of secondary wall-associated transcription factors and genes involved in secondary wall biosynthesis and programmed cell death. As a result, many normally parenchymatous cells in leaves and stems acquired thickened secondary walls in the VND1 to VND5 overexpressors. In contrast, dominant repression of VND3 function resulted in reduced secondary wall thickening in vessels and a collapsed vessel phenotype. In addition, VND1 to VND5 were shown to be capable of rescuing the secondary wall defects in the fibers of the snd1 nst1 double mutant when expressed under the SND1 promoter. Furthermore, transactivation analysis revealed that VND1 to VND5 could activate expression of the GUS reporter gene driven by the secondary wall NAC binding element (SNBE). Together, these results demonstrate that VND1 to VND5 possess functions similar to that of the SND1 secondary wall NAC and are transcriptional regulators of secondary wall biosynthesis in vessels. PMID:25148240

  12. Growth Description for Vessel Wall Adaptation: A Thick-Walled Mixture Model of Abdominal Aortic Aneurysm Evolution.

    PubMed

    Grytsan, Andrii; Eriksson, Thomas S E; Watton, Paul N; Gasser, T Christian

    2017-08-25

    (1) Background: Vascular tissue seems to adapt towards stable homeostatic mechanical conditions, however, failure of reaching homeostasis may result in pathologies. Current vascular tissue adaptation models use many ad hoc assumptions, the implications of which are far from being fully understood; (2) Methods: The present study investigates the plausibility of different growth kinematics in modeling Abdominal Aortic Aneurysm (AAA) evolution in time. A structurally motivated constitutive description for the vessel wall is coupled to multi-constituent tissue growth descriptions; Constituent deposition preserved either the constituent's density or its volume, and Isotropic Volume Growth (IVG), in-Plane Volume Growth (PVG), in-Thickness Volume Growth (TVG) and No Volume Growth (NVG) describe the kinematics of the growing vessel wall. The sensitivity of key modeling parameters is explored, and predictions are assessed for their plausibility; (3) Results: AAA development based on TVG and NVG kinematics provided not only quantitatively, but also qualitatively different results compared to IVG and PVG kinematics. Specifically, for IVG and PVG kinematics, increasing collagen mass production accelerated AAA expansion which seems counterintuitive. In addition, TVG and NVG kinematics showed less sensitivity to the initial constituent volume fractions, than predictions based on IVG and PVG; (4) Conclusions: The choice of tissue growth kinematics is of crucial importance when modeling AAA growth. Much more interdisciplinary experimental work is required to develop and validate vascular tissue adaption models, before such models can be of any practical use.

  13. Vessel wall enhancement in the diagnosis and management of primary angiitis of the central nervous system in children.

    PubMed

    Ohno, Koyo; Saito, Yoshiaki; Kurata, Hirofumi; Saiki, Yusuke; Ohtahara, Hiroko; Yoshioka, Hiroki; Yamashita, Eijiro; Fujii, Shinya; Maegaki, Yoshihiro

    2016-08-01

    We describe two cases of primary angiitis of the central nervous system in children (cPACNS) diagnosed by vessel wall contrast enhancement on magnetic resonance imaging (MRI). Both patients developed acute cerebral infarction after fever and malaise. In patient 1, a 7-month-old boy, MRI revealed extensive cerebral infarction in the right middle cerebral artery (MCA) area and stenosis at the M1 portion of the right MCA. Oral glucocorticoid therapy was initiated. Vessel wall enhancement was ameliorated 3months after onset, and stenosis was mostly restored. Patient 2, a 5-year-old boy, suffered from cerebral infarction in the left MCA area, and stenosis was identified in the left internal carotid artery, left MCA, and left posterior cerebral artery. Although vessel wall enhancement was reduced after glucocorticoid therapy, vessel wall enhancement of left MCA re-emerged, accompanied by increased erythrocyte sedimentation rate (ESR) and, decreased cerebral blood flow (CBF) in the affected hemisphere. Intravenous methylprednisolone therapy followed by oral glucocorticoid and mycophenolate mofetil resulted in resolution of these findings. Vessel wall enhancement is a promising finding in the diagnosis of cPACNS. Disease flares occur rarely in medium-to-large vessel cPACNS during dose tapering. Vessel wall enhancement, ESR, and CBF may be useful for the assessment of the activity of angiitis.

  14. Impact of deep vessel wall injury and vessel stretching on subsequent arterial remodeling after balloon angioplasty: a serial intravascular ultrasound study.

    PubMed

    Okura, Hiroyuki; Shimodozono, Shinichi; Hayase, Motoya; Bonneau, Heidi N; Yock, Paul G; Fitzgerald, Peter J

    2002-08-01

    Arterial remodeling has been shown to be responsible for lumen narrowing after nonstent interventions. To examine the impact of deep vessel wall injury (DI) after balloon angioplasty on the subsequent vessel remodeling process, we performed serial intravascular ultrasound (IVUS) analysis in 47 native coronary artery lesions that underwent balloon angioplasty. An IVUS study was performed before and after balloon angioplasty and repeated at follow-up. Vessel and lumen area were measured at the narrowest site before intervention. Plaque area was calculated as vessel area minus lumen area. DI was defined as the presence of plaque/vessel wall fracture deep in the medial layer (sonolucent zone by IVUS) after angioplasty. After angioplasty, DI was present in 18 (38%, DI group) and absent in 29 (62%, non-DI group) of lesions. During follow-up, changes in vessel area in the DI group were significantly larger than in the non-DI group (P =.007). There were no significant differences in changes in plaque area. A trend toward greater late lumen loss was observed in the non-DI group (P =.05). In the DI group, changes in lumen area correlated better with changes in vessel area (r = 0.81, P <.0001) than with changes in plaque area (r = 0.32, P =.20). However, in the non-DI group, changes in lumen area correlated with changes in plaque area (r = -0.55, P =.002), but not with changes in vessel area (r = 0.30, P =.11). Deep vessel wall injury after balloon angioplasty is associated with the magnitude of the subsequent vessel remodeling process. The differences in the remodeling process may have implications regarding adjunctive therapies to prevent restenosis after balloon angioplasty.

  15. Cerebral amyloid angiopathy in the elderly: vessel walls changes and relationship with dementia.

    PubMed

    Zekry, Dina; Duyckaerts, Charles; Belmin, Joël; Geoffre, Caroline; Moulias, Robert; Hauw, Jean-Jacques

    2003-10-01

    Abeta peptide deposits are observed in brain cortical and leptomeningeal microvessels in a few families, in patients with Alzheimer's disease and in cognitively normal elderly subjects. These deposits, which cause Abeta amyloid angiopathy, are usually associated with other lesions induced by Abeta peptide and tau pathologies. To investigate the consequences of cerebral amyloid angiopathy on arterial morphology and search for correlations with the degree of cognitive impairment, we carried out a prospective clinicopathological and morphometric study in 29 institutionalized elderly patients cognitively normal or affected with sporadic dementia associated with Alzheimer-type lesions, cerebral infarcts or both. We measured the external and internal diameters of arteries 40-120 microm wide, containing moderate or severe Abeta deposits, and of unaffected arteries in the temporal and frontal lobes. We found no differences in the mean external diameters. In contrast, the mean internal diameters of vessels with moderate Abeta deposits were smaller than those of unaffected vessels. Conversely, the internal diameters of severely affected vessels were larger than those of unaffected vessels. This suggests that arterial walls become thicker during the early stages of amyloid angiopathy, and the diameter of the lumen decreases, whereas during advanced stages, the walls become thinner and the lumen becomes larger. In addition, we assessed the overall severity of amyloid angiopathy. This showed that thinner arterial walls and the severity of amyloid angiopathy were correlated to dementia. In a multivariate model that integrates the other macroscopic and microscopic lesions that may be implied in the mechanism of cognitive impairment, the severity of amyloid angiopathy per se explained 10% of the variability in the cognitive impairment.

  16. Primary Metabolism during Biosynthesis of Secondary Wall Polymers of Protoxylem Vessel Elements1[OPEN

    PubMed Central

    Morisaki, Keiko; Sawada, Yuji; Sano, Ryosuke; Yamamoto, Atsushi; Kurata, Tetsuya; Suzuki, Shiro; Matsuda, Mami; Hasunuma, Tomohisa; Hirai, Masami Yokota

    2016-01-01

    Xylem vessels, the water-conducting cells in vascular plants, undergo characteristic secondary wall deposition and programmed cell death. These processes are regulated by the VASCULAR-RELATED NAC-DOMAIN (VND) transcription factors. Here, to identify changes in metabolism that occur during protoxylem vessel element differentiation, we subjected tobacco (Nicotiana tabacum) BY-2 suspension culture cells carrying an inducible VND7 system to liquid chromatography-mass spectrometry-based wide-target metabolome analysis and transcriptome analysis. Time-course data for 128 metabolites showed dynamic changes in metabolites related to amino acid biosynthesis. The concentration of glyceraldehyde 3-phosphate, an important intermediate of the glycolysis pathway, immediately decreased in the initial stages of cell differentiation. As cell differentiation progressed, specific amino acids accumulated, including the shikimate-related amino acids and the translocatable nitrogen-rich amino acid arginine. Transcriptome data indicated that cell differentiation involved the active up-regulation of genes encoding the enzymes catalyzing fructose 6-phosphate biosynthesis from glyceraldehyde 3-phosphate, phosphoenolpyruvate biosynthesis from oxaloacetate, and phenylalanine biosynthesis, which includes shikimate pathway enzymes. Concomitantly, active changes in the amount of fructose 6-phosphate and phosphoenolpyruvate were detected during cell differentiation. Taken together, our results show that protoxylem vessel element differentiation is associated with changes in primary metabolism, which could facilitate the production of polysaccharides and lignin monomers and, thus, promote the formation of the secondary cell wall. Also, these metabolic shifts correlate with the active transcriptional regulation of specific enzyme genes. Therefore, our observations indicate that primary metabolism is actively regulated during protoxylem vessel element differentiation to alter the cell’s metabolic

  17. Design and preliminary tests of a family of adaptive waveforms to measure blood vessel diameter and wall thickness.

    PubMed

    Ai, Yuhui; Jaffe, Jules S

    2005-02-01

    In this article we consider the adaptive design of waveforms to be used in vascular ultrasound. The advantage of these waveforms, when used with the proposed processing scheme, is that their application results in increased reflected energy, especially when compared with more conventional methods such as a short-gated sinusoid. This increase in reflected energy has potential to permit inferences to be made about wall thickness and vessel diameter from deeper vessels than possible with more traditional techniques. Here, the use of waveforms of the type A(t)ej(kt2), 0 < or = t < or = b, where A(t) is a specially designed envelope and k a sweep frequency, is proposed. Theorems are proved that describe how to choose an A(t) which results in either a maximum of reflected energy signal-to-noise ratio (SNR), or range resolution. The design of the waveform is adaptive in that both A(t) and k are derived in consideration of a specific blood vessel whose transfer function has been obtained experimentally. Numerical simulations illustrate the advantages of using these waveforms as well as the effects of the parameters. A simple experimental implementation of the methodology is presented on a brachial artery. The measurement of the impulse response of the artery is presented in this context. Results indicate that a processing gain in SNR over the instantaneous values obtained from the raw echo waveforms of 11 dB to 14 dB can be obtained via this methodology.

  18. Added Value of Vessel Wall Magnetic Resonance Imaging in the Differentiation of Moyamoya Vasculopathies in a Non-Asian Cohort.

    PubMed

    Mossa-Basha, Mahmud; de Havenon, Adam; Becker, Kyra J; Hallam, Danial K; Levitt, Michael R; Cohen, Wendy A; Hippe, Daniel S; Alexander, Matthew D; Tirschwell, David L; Hatsukami, Thomas; Amlie-Lefond, Catherine; Yuan, Chun

    2016-07-01

    Although studies have evaluated the differential imaging of moyamoya disease and atherosclerosis, none have investigated the added value of vessel wall magnetic resonance imaging (MRI). This study evaluates the added diagnostic value of vessel wall MRI in differentiating moyamoya disease, atherosclerotic-moyamoya syndrome (A-MMS), and vasculitic-MMS (V-MMS) with a multicontrast protocol. We retrospectively reviewed the carotid artery territories of patients with clinically defined vasculopathies (moyamoya disease, atherosclerosis, and vasculitis) and steno-occlusive intracranial carotid disease. Two neuroradiologists, blinded to clinical data reviewed the luminal imaging of each carotid, evaluating collateral extent and making a presumed diagnosis with diagnostic confidence. After 3 weeks, the 2 readers reviewed the luminal imaging+vessel wall MRI for the presence, pattern and intensity of postcontrast enhancement, T2 signal characteristics, pattern of involvement, and presumed diagnosis and confidence. Ten A-MMS, 3 V-MMS, and 8 moyamoya disease cases with 38 affected carotid segments were included. There was significant improvement in diagnostic accuracy with luminal imaging+vessel wall MRI when compared with luminal imaging (87% versus 32%, P<0.001). The most common vessel wall MRI findings for moyamoya disease were nonenhancing, nonremodeling lesions without T2 heterogeneity; for A-MMS eccentric, remodeling, and T2 heterogeneous lesions with mild/moderate and homogeneous/heterogeneous enhancement; and for V-MMS concentric lesions with homogeneous, moderate enhancement. Inter-reader agreement was moderate to substantial for all vessel wall MRI characteristics (κ=0.46-0.86) and fair for collateral grading (κ=0.35). There was 11% inter-reader agreement for diagnosis on luminal imaging when compared with 82% for luminal imaging+vessel wall MRI (P<0.001). Vessel wall MRI can significantly improve the differentiation of moyamoya vasculopathies when combined with

  19. SPR salt wall leaching experiments in lab-scale vessel : data report.

    SciTech Connect

    Webb, Stephen Walter; O'Hern, Timothy John; Hartenberger, Joel David

    2010-10-01

    During cavern leaching in the Strategic Petroleum Reserve (SPR), injected raw water mixes with resident brine and eventually interacts with the cavern salt walls. This report provides a record of data acquired during a series of experiments designed to measure the leaching rate of salt walls in a labscale simulated cavern, as well as discussion of the data. These results should be of value to validate computational fluid dynamics (CFD) models used to simulate leaching applications. Three experiments were run in the transparent 89-cm (35-inch) ID diameter vessel previously used for several related projects. Diagnostics included tracking the salt wall dissolution rate using ultrasonics, an underwater camera to view pre-installed markers, and pre- and post-test weighing and measuring salt blocks that comprise the walls. In addition, profiles of the local brine/water conductivity and temperature were acquired at three locations by traversing conductivity probes to map out the mixing of injected raw water with the surrounding brine. The data are generally as expected, with stronger dissolution when the salt walls were exposed to water with lower salt saturation, and overall reasonable wall shape profiles. However, there are significant block-to-block variations, even between neighboring salt blocks, so the averaged data are considered more useful for model validation. The remedial leach tests clearly showed that less mixing and longer exposure time to unsaturated water led to higher levels of salt wall dissolution. The data for all three tests showed a dividing line between upper and lower regions, roughly above and below the fresh water injection point, with higher salt wall dissolution in all cases, and stronger (for remedial leach cases) or weaker (for standard leach configuration) concentration gradients above the dividing line.

  20. Comparison of viscoelastic properties of walls and functional characteristics of valves in lymphatic and venous vessels.

    PubMed

    Ohhashi, T

    1987-12-01

    The principal function of the lymphatic and venous system is to maintain a favorable environment for cells of the body. As a consequence mainly of hydrostatic forces, shifts of fluid usually occur between the vascular system and the extracellular space. To compensate for these shifts the veins are capable of active and passive changes in capacity that serve to modulate the filling pressure of the heart by adjusting the central blood volume. In addition to the venous function, the lymphatic function also contributes to compensate for the fluid shifts by drainage from the interstitial space. Namely, the general function of the lymphatic system is to return fluid and protein which escapes from the blood capillaries to the lymph circulation. To elucidate the mode of venous and lymph transport, therefore, it is of essential importance to obtain basic knowledge of the mechanical characteristics of the walls of the vessels and the functional characteristics of the lymphatic and venous valves dividing two adjacent compartments. In this communication, in order to answer the question, "Are Lymphatics Different From Blood Vessels?", I would like to review a comparison of viscoelastic properties of walls and functional characteristics of valves in lymph and venous vessels by use of our original data obtained with isolated canine veins and thoracic ducts and with isolated bovine mesenteric lymphatics (1-9).

  1. Automatic segmentation of lymph vessel wall using optimal surface graph cut and hidden Markov Models.

    PubMed

    Jones, Jonathan-Lee; Essa, Ehab; Xie, Xianghua

    2015-01-01

    We present a novel method to segment the lymph vessel wall in confocal microscopy images using Optimal Surface Segmentation (OSS) and hidden Markov Models (HMM). OSS is used to preform a pre-segmentation on the images, to act as the initial state for the HMM. We utilize a steerable filter to determine edge based filters for both of these segmentations, and use these features to build Gaussian probability distributions for both the vessel walls and the background. From this we infer the emission probability for the HMM, and the transmission probability is learned using a Baum-Welch algorithm. We transform the segmentation problem into one of cost minimization, with each node in the graph corresponding to one state, and the weight for each node being defined using its emission probability. We define the inter-relations between neighboring nodes using the transmission probability. Having constructed the problem, it is solved using the Viterbi algorithm, allowing the vessel to be reconstructed. The optimal solution can be found in polynomial time. We present qualitative and quantitative analysis to show the performance of the proposed method.

  2. An Ultrasound Simulation Model for the Pulsatile Blood Flow Modulated by the Motion of Stenosed Vessel Wall.

    PubMed

    Zhang, Qinghui; Zhang, Yufeng; Zhou, Yi; Zhang, Kun; Zhang, Kexin; Gao, Lian

    2016-01-01

    This paper presents an ultrasound simulation model for pulsatile blood flow, modulated by the motion of a stenosed vessel wall. It aims at generating more realistic ultrasonic signals to provide an environment for evaluating ultrasound signal processing and imaging and a framework for investigating the behaviors of blood flow field modulated by wall motion. This model takes into account fluid-structure interaction, blood pulsatility, stenosis of the vessel, and arterial wall movement caused by surrounding tissue's motion. The axial and radial velocity distributions of blood and the displacement of vessel wall are calculated by solving coupled Navier-Stokes and wall equations. With these obtained values, we made several different phantoms by treating blood and the vessel wall as a group of point scatterers. Then, ultrasound echoed signals from oscillating wall and blood in the axisymmetric stenotic-carotid arteries were computed by ultrasound simulation software, Field II. The results show better consistency with corresponding theoretical values and clinical data and reflect the influence of wall movement on the flow field. It can serve as an effective tool not only for investigating the behavior of blood flow field modulated by wall motion but also for quantitative or qualitative evaluation of new ultrasound imaging technology and estimation method of blood velocity.

  3. An Ultrasound Simulation Model for the Pulsatile Blood Flow Modulated by the Motion of Stenosed Vessel Wall

    PubMed Central

    Zhou, Yi; Zhang, Kun; Zhang, Kexin; Gao, Lian

    2016-01-01

    This paper presents an ultrasound simulation model for pulsatile blood flow, modulated by the motion of a stenosed vessel wall. It aims at generating more realistic ultrasonic signals to provide an environment for evaluating ultrasound signal processing and imaging and a framework for investigating the behaviors of blood flow field modulated by wall motion. This model takes into account fluid-structure interaction, blood pulsatility, stenosis of the vessel, and arterial wall movement caused by surrounding tissue's motion. The axial and radial velocity distributions of blood and the displacement of vessel wall are calculated by solving coupled Navier-Stokes and wall equations. With these obtained values, we made several different phantoms by treating blood and the vessel wall as a group of point scatterers. Then, ultrasound echoed signals from oscillating wall and blood in the axisymmetric stenotic-carotid arteries were computed by ultrasound simulation software, Field II. The results show better consistency with corresponding theoretical values and clinical data and reflect the influence of wall movement on the flow field. It can serve as an effective tool not only for investigating the behavior of blood flow field modulated by wall motion but also for quantitative or qualitative evaluation of new ultrasound imaging technology and estimation method of blood velocity. PMID:27478840

  4. A completely noninvasive method of dissolved oxygen monitoring in disposable small-scale cell culture vessels based on diffusion through permeable vessel walls.

    PubMed

    Gupta, Priyanka A; Ge, Xudong; Kostov, Yordan; Rao, Govind

    2014-01-01

    Disposable cell culture vessels are extensively used at small scales for process optimization and validation, but they lack monitoring capabilities. Optical sensors that can be easily adapted for use in small-scale vessels are commercially available for pH, dissolved oxygen (DO), and dissolved carbon dioxide (DCO2 ). However, their use has been limited due to the contamination and compatibility issues. We have developed a novel solution to these problems for DO monitoring. Oxygen diffusion through permeable vessel wall can be exploited for noninvasive monitoring. An optical oxygen sensor can be placed outside the oxygen permeable vessel wall thereby allowing oxygen diffusing through the vessel wall to be detected by the sensor. This way the sensor stays separate from the cell culture and there are no concerns about contaminants or leachants. Here we implement this method for two cell culture devices: polystyrene-made T-75 tissue culture flask and fluorinated ethylene propylene (FEP)-made Vuelife(®) cell culture bag. Additionally, mammalian and microbial cell cultures were performed in Vuelife(®) cell culture bags, proving that a sensor placed outside can be used to track changes in cell cultures. This approach toward noninvasive monitoring will help in integrating cell culture vessels with sensors in a seamless manner. © 2013 American Institute of Chemical Engineers.

  5. A wall-crawling robot for reactor vessel inspection in advanced reactors

    SciTech Connect

    Spelt, P.F.; Crane, C.; Feng, L.; Abidi, M.; Tosunoglu, S.

    1994-06-01

    A consortium of four universities and the Center for Engineering Systems Advanced Research of the Oak Ridge National Laboratory has designed a prototype wall-crawling robot to perform weld inspection in advanced nuclear reactors. Design efforts for the reactor vessel inspection robot (RVIR) concentrated on the Advanced Liquid Metal Reactor because it presents the most demanding environment in which such a robot must operate. The RVIR consists of a chassis containing two sets of suction cups that can alternately grasp the side of the vessel being inspected, providing both locomotion and steering functions. Sensors include three CCD cameras and a weld inspection device based on new shear-wave technology. The restrictions of the inspection environment presented major challenges to the team. These challenges were met in the prototype, which has been tested in a non-radiation, room-temperature mockup of the robot work environment and shown to perform as expected.

  6. Spinning Disk Confocal Microscopy of Calcium Signalling in Blood Vessel Walls

    PubMed Central

    Nelson, Mark; Ledoux, Jonathan; Taylor, Mark; Bonev, Adrian; Hannah, Rachael; Solodushko, Viktoriya; Shui, Bo; Tallini, Yvonne; Kotlikoff, Michael

    2010-01-01

    Spinning disk confocal laser microscopy systems can be used for observing fast events occurring in a small volume when they include a sensitive electron-multiplying CCD camera. Such a confocal system was recently used to capture the first pictures of intracellular calcium signalling within the projections of endothelial cells to the adjacent smooth muscle cells in the blood vessel wall. Detection of these calcium signals required high spatial and temporal resolution. A newly developed calcium ion (Ca2+) biosensor was also used. This exclusively expressed in the endothelium and fluoresced when Ca2+ concentrations increased during signalling. This work gives insights into blood vessel disease because Ca2+ signalling is critical for blood flow and pressure regulation. PMID:22506097

  7. Fabrication of double-walled section models of the ITER vacuum vessel

    SciTech Connect

    Koizumi, K.; Kanamori, N.; Nakahira, M.; Itoh, Y.; Horie, M.; Tada, E.; Shimamoto, S.

    1995-12-31

    Trial fabrication of double-walled section models has been performed at Japan Atomic Energy Research Institute (JAERI) for the construction of ITER vacuum vessel. By employing TIG (Tungsten-arc Inert Gas) welding and EB (Electron Beam) welding, for each model, two full-scaled section models of 7.5 {degree} toroidal sector in the curved section at the bottom of vacuum vessel have been successfully fabricated with the final dimensional error of within {+-}5 mm to the nominal values. The sufficient technical database on the candidate fabrication procedures, welding distortion and dimensional stability of full-scaled models have been obtained through the fabrications. This paper describes the design and fabrication procedures of both full-scaled section models and the major results obtained through the fabrication.

  8. Signaling role of oligogalacturonides derived during cell wall degradation

    PubMed Central

    Vallarino, José G.; Osorio, Sonia

    2012-01-01

    In addition to the role of the cell wall as a physical barrier against pathogens, some of its constituents, such as pectin-derived oligogalacturonides (OGAs) are essential components to trigger signaling pathways that induce rapid defense responses. Many pathogens directly penetrate the cell wall to access water and nutrients of the plant protoplast, and a rigid cell wall can fend off pathogen attack by forming an impenetrable physical barrier. Thus, cell wall integrity sensing is one mechanism by which plants may detect pathogen attack. Moreover, when the plant-pathogen interaction occurred, OGAs released during cell wall modification can trigger plant defense (e.g., production of reactive oxygen species, production of anti-microbial metabolites and synthesis of pathogenesis-related proteins). This review documents and discusses studies suggesting that OGAs play a dual signaling role during pathogen attack by inducing defense responses and plant architecture adjustment. PMID:22918501

  9. General and crevice corrosion study of the in-wall shielding materials for ITER vacuum vessel

    NASA Astrophysics Data System (ADS)

    Joshi, K. S.; Pathak, H. A.; Dayal, R. K.; Bafna, V. K.; Kimihiro, Ioki; Barabash, V.

    2012-11-01

    Vacuum vessel In-Wall Shield (IWS) will be inserted between the inner and outer shells of the ITER vacuum vessel. The behaviour of IWS in the vacuum vessel especially concerning the susceptibility to crevice of shielding block assemblies could cause rapid and extensive corrosion attacks. Even galvanic corrosion may be due to different metals in same electrolyte. IWS blocks are not accessible until life of the machine after closing of vacuum vessel. Hence, it is necessary to study the susceptibility of IWS materials to general corrosion and crevice corrosion under operations of ITER vacuum vessel. Corrosion properties of IWS materials were studied by using (i) Immersion technique and (ii) Electro-chemical Polarization techniques. All the sample materials were subjected to a series of examinations before and after immersion test, like Loss/Gain weight measurement, SEM analysis, and Optical stereo microscopy, measurement of surface profile and hardness of materials. After immersion test, SS 304B4 and SS 304B7 showed slight weight gain which indicate oxide layer formation on the surface of coupons. The SS 430 material showed negligible weight loss which indicates mild general corrosion effect. On visual observation with SEM and Metallography, all material showed pitting corrosion attack. All sample materials were subjected to series of measurements like Open Circuit potential, Cyclic polarization, Pitting potential, protection potential, Critical anodic current and SEM examination. All materials show pitting loop in OC2 operating condition. However, its absence in OC1 operating condition clearly indicates the activity of chloride ion to penetrate oxide layer on the sample surface, at higher temperature. The critical pitting temperature of all samples remains between 100° and 200°C.

  10. A simulation environment for validating ultrasonic blood flow and vessel wall imaging based on fluid-structure interaction simulations: ultrasonic assessment of arterial distension and wall shear rate.

    PubMed

    Swillens, Abigail; Degroote, Joris; Vierendeels, Jan; Lovstakken, Lasse; Segers, Patrick

    2010-08-01

    Ultrasound (US) is a commonly used vascular imaging tool when screening for patients at high cardiovascular risk. However, current blood flow and vessel wall imaging methods are hampered by several limitations. When optimizing and developing new ultrasound modalities, proper validation is required before clinical implementation. Therefore, the authors present a simulation environment integrating ultrasound and fluid-structure interaction (FSI) simulations, allowing construction of synthetic ultrasound images based on physiologically realistic behavior of an artery. To demonstrate the potential of the model for vascular ultrasound research, the authors studied clinically relevant imaging modalities of arterial function related to both vessel wall deformation and arterial hemodynamics: Arterial distension (related to arterial stiffness) and wall shear rate (related to the development of atherosclerosis) imaging. An in-house code ("TANGO") was developed to strongly couple the flow solver FLUENT and structural solver ABAQUS using an interface quasi-Newton technique. FIELD II was used to model realistic transducer and scan settings. The input to the FSI-US model is a scatterer phantom on which the US waves reflect, with the scatterer displacement derived from the FSI flow and displacement fields. The authors applied the simulation tool to a 3D straight tube, representative of the common carotid artery (length: 5 cm; and inner and outer radius: 3 and 4 mm). A mass flow inlet boundary condition, based on flow measured in a healthy subject, was applied. A downstream pressure condition, based on a noninvasively measured pressure waveform, was chosen and scaled to simulate three different degrees of arterial distension (1%, 4%, and 9%). The RF data from the FSI-US coupling were further processed for arterial wall and flow imaging. Using an available wall tracking algorithm, arterial distensibility was assessed. Using an autocorrelation estimator, blood velocity and shear

  11. Some properties of the walls of metaxylem vessels of maize roots, including tests of the wettability of their lumenal wall surfaces

    PubMed Central

    McCully, Margaret; Canny, Martin; Baker, Adam; Miller, Celia

    2014-01-01

    Background and Aims Since the proposal of the cohesion theory there has been a paradox that the lumenal surface of vessels is rich in hydrophobic lignin, while tension in the rising sap requires adhesion to a hydrophilic surface. This study sought to characterize the strength of that adhesion in maize (Zea mays), the wettability of the vessel surface, and to reconcile this with its histochemical and physical nature. Methods Wettability was assessed by emptying the maize root vessels of sap, perfusing them with either water or oil, and examining the adhesion (as revealed by contact angles) of the two liquids to vessel walls by cryo-scanning electron microscopy. The phobicity of the lumenal surface was also assessed histochemically with hydrophilic and hydrophobic probes. Key Results Pit borders in the lumen-facing vessel wall surface were wetted by both sap/water and oil. The attraction for oil was weaker: water could replace oil but not vice versa. Pit apertures repelled oil and were strongly stained by hydrophilic probes. Pit chambers were probably hydrophilic. Oil never entered the pits. When vessels were emptied and cryo-fixed immediately, pit chambers facing away from the vessels were always sap-filled. Pit chambers facing vessel lumens were either sap- or gas-filled. Sap from adjoining tracheary elements entering empty vessels accumulated on the lumenal surface in hemispherical drops, which spread out with decreasing contact angles to fill the lumen. Conclusions The vessel lumenal surface has a dual nature, namely a mosaic of hydrophilic and hydrophobic patches at the micrometre scale, with hydrophilic predominating. A key role is shown, for the first time, of overarching borders of pits in determining the dual nature of the surface. In gas-filled (embolized) vessels they are hydrophobic. When wetted by sap (vessels refilling or full) they are hydrophilic. A hypothesis is proposed to explain the switch between the two states. PMID:24709790

  12. Low-density lipoprotein transport in blood vessel walls of squirrel monkeys

    SciTech Connect

    Tompkins, R.G.; Yarmush, M.L.; Schnitzer, J.J.; Colton, C.K.; Smith, K.A.; Stemerman, M.B. )

    1989-08-01

    Transmural accumulations of low-density lipoprotein (LDL) were examined in the blood vessel walls of four squirrel monkeys. Vascular wall concentrations of LDL were measured using quantitative autoradiography after {sup 125}I-labeled LDL circulation for 30 min. Profiles of relative tissue concentration from different sections in the same region were similar to each other, and there was little animal-to-animal variation. Concentrations were highest near the luminal endothelium, lower near the medial-adventitial border, and lowest within the media. Profiles from different regions fell into three groups: (1) aortic samples had steep intimal concentration gradients and near-zero media concentrations; (2) the iliac, femoral, popliteal, and common carotid arteries had higher intimal concentrations than group 1 but had similar concentrations deep within the media; and (3) the cerebral and coronary arteries, inferior vena cava, and pulmonary artery had intimal concentrations that were similar to group 2, but the concentrations deep within the media were greater than either groups 1 or 2. Arterial bifurcation profiles from the inner wall and the outer walls were similar to each other and to profiles from the upstream and downstream areas. Out of 280 total sites examined, 15 examples of profiles with substantially increased concentrations near the luminal endothelium were found scattered throughout the cardiovascular system, demonstrating that there are focal regions throughout the cardiovascular system which have greatly increased {sup 125}I-LDL transendothelial permeability.

  13. Optimal 3-D culture of primary articular chondrocytes for use in the Rotating Wall Vessel Bioreactor

    PubMed Central

    Mellor, Liliana F.; Baker, Travis L.; Brown, Raquel J.; Catlin, Lindsey W.; Oxford, Julia Thom

    2014-01-01

    INTRODUCTION Reliable culturing methods for primary articular chondrocytes are essential to study the effects of loading and unloading on joint tissue at the cellular level. Due to the limited proliferation capacity of primary chondrocytes and their tendency to dedifferentiate in conventional culture conditions, long-term culturing conditions of primary chondrocytes can be challenging. The goal of this study was to develop a suspension culturing technique that not only would retain the cellular morphology but also maintain gene expression characteristics of primary articular chondrocytes. METHODS Three-dimensional culturing methods were compared and optimized for primary articular chondrocytes in the rotating wall vessel bioreactor, which changes the mechanical culture conditions to provide a form of suspension culture optimized for low shear and turbulence. We performed gene expression analysis and morphological characterization of cells cultured in alginate beads, Cytopore-2 microcarriers, primary monolayer culture, and passaged monolayer cultures using reverse transcription-PCR and laser scanning confocal microscopy. RESULTS Primary chondrocytes grown on Cytopore-2 microcarriers maintained the phenotypical morphology and gene expression pattern observed in primary bovine articular chondrocytes, and retained these characteristics for up to 9 days. DISCUSSION Our results provide a novel and alternative culturing technique for primary chondrocytes suitable for studies that require suspension such as those using the rotating wall vessel bioreactor. In addition, we provide an alternative culturing technique for primary chondrocytes that can impact future mechanistic studies of osteoarthritis progression, treatments for cartilage damage and repair, and cartilage tissue engineering. PMID:25199120

  14. Localization and differential regulation of angiotensinogen mRNA expression in the vessel wall.

    PubMed Central

    Naftilan, A J; Zuo, W M; Inglefinger, J; Ryan, T J; Pratt, R E; Dzau, V J

    1991-01-01

    Recent data demonstrate the existence of a vascular renin angiotensin system. In this study we examine the localization of angiotensinogen mRNA in the blood vessel wall of two rat strains, the Wistar and Wistar Kyoto (WKY), as well as the regulation of vascular angiotensinogen mRNA expression by dietary sodium. Northern blot analysis and in situ hybridization histochemistry demonstrate that in both strains angiotensinogen mRNA is detected in the aortic medial smooth muscle layer as well as the periaortic fat. In WKY rats fed a 1.6% sodium diet, angiotensinogen mRNA concentration is 2.6-fold higher in the periaortic fat than in the smooth muscle, as analyzed by quantitative slot blot hybridization. Angiotensinogen mRNA expression in the medial smooth muscle layer is sodium regulated. After 5 d of a low (0.02%) sodium diet, smooth muscle angiotensinogen mRNA levels increase 3.2-fold (P less than 0.005) as compared with the 1.6% sodium diet. In contrast, angiotensinogen mRNA level in the periaortic fat is not influenced by sodium diet. In summary, our data demonstrate regional (smooth muscle vs. periaortic fat) differential regulation of angiotensinogen mRNA levels in the blood vessel wall by sodium. This regional differential regulation by sodium may have important physiological implications. Images PMID:2010543

  15. Catheter ultrasound for cross-sectional imaging and drug delivery to vessel wall

    NASA Astrophysics Data System (ADS)

    Hossack, John A.

    2015-05-01

    Current methods for delivery of an anti-restenosis drug to an arterial vessel wall post-percutaneous transluminal angioplasty and stent placement are limited in terms of drug choice, dosing level, and ability to assure drug coverage between the struts of a drug eluting stent. Intravascular ultrasound (IVUS) provides real-time, radiation-free, imaging and assessment of atherosclerotic disease in terms of anatomical, functional and molecular information. In this presentation, the design of a dual imaging / therapy IVUS catheter is described and results documenting gene and drug delivery reported. Microbubbles and drug / gene (shell associated or co-injected) are dispensed from the catheter tip. Using this approach, it becomes possible to address the need for complete vessel wall coverage and achieve delivery in regions poorly addressed using conventional stent-based approaches. A range of in vitro, ex vivo and in vivo results are presented. Our most recent results involve a demonstration in a pig model of coronary balloon angioplasty that produced a 33% reduction in neointima formation versus a drug plus microbubble, but no ultrasound, control.

  16. Predicting Progression of Intracranial Arteriopathies in Childhood Stroke With Vessel Wall Imaging.

    PubMed

    Stence, Nicholas V; Pabst, Lisa L; Hollatz, Amanda L; Mirsky, David M; Herson, Paco S; Poisson, Sharon; Traystman, Richard J; Bernard, Timothy J

    2017-08-01

    Childhood arterial ischemic stroke is frequently associated with an intracranial arteriopathy that often progresses in the first 3 to 6 months post stroke. We hypothesized that children with enhancing arteriopathies on vessel wall imaging (VWI) would have a higher risk of arteriopathy progression than those without enhancement. Our institutional radiographic database was searched for cases of childhood stroke with VWI. Inclusion criteria consisted of age ranging from 1 month through 20 years, diagnosis of arterial ischemic stroke, available VWI, and follow-up magnetic resonance angiogram. Imaging was reviewed to systematically describe VWI findings, categorize arteriopathies, steroid therapy, and identify progressive arteriopathies using CACADE definitions. Sixteen cases of childhood stroke at Children's Hospital Colorado between January 1, 2010 and July 1, 2016 were reviewed. Strong vessel wall enhancement at presentation was associated with progressive arteriopathy in 83% of cases (10/12), when compared with 0% (0/4) without strong enhancement (P=0.008). Our case series demonstrates the potential benefit of VWI in children with stroke because it may identify patients who will have progressive arterial disease. © 2017 American Heart Association, Inc.

  17. Ex vivo blood vessel bioreactor for analysis of the biodegradation of magnesium stent models with and without vessel wall integration.

    PubMed

    Wang, Juan; Liu, Lumei; Wu, Yifan; Maitz, Manfred F; Wang, Zhihong; Koo, Youngmi; Zhao, Ansha; Sankar, Jagannathan; Kong, Deling; Huang, Nan; Yun, Yeoheung

    2017-03-01

    Current in vitro models fail in predicting the degradation rate and mode of magnesium (Mg) stents in vivo. To overcome this, the microenvironment of the stent is simulated here in an ex vivo bioreactor with porcine aorta and circulating medium, and compared with standard static in vitro immersion and with in vivo rat aorta models. In ex vivo and in vivo conditions, pure Mg wires were exposed to the aortic lumen and inserted into the aortic wall to mimic early- and long-term implantation, respectively. Results showed that: 1) Degradation rates of Mg were similar for all the fluid diffusion conditions (in vitro static, aortic wall ex vivo and in vivo); however, Mg degradation under flow condition (i.e. in the lumen) in vivo was slower than ex vivo; 2) The corrosion mode in the samples can be mainly described as localized (in vitro), mixed localized and uniform (ex vivo), and uniform (in vivo); 3) Abundant degradation products (MgO/Mg(OH)2 and Ca/P) with gas bubbles accumulated around the localized degradation regions ex vivo, but a uniform and thin degradation product layer was found in vivo. It is concluded that the ex vivo vascular bioreactor provides an improved test setting for magnesium degradation between static immersion and animal experiments and highlights its promising role in bridging degradation behavior and biological response for vascular stent research. Magnesium and its alloys are candidates for a new generation of biodegradable stent materials. However, the in vitro degradation of magnesium stents does not match the clinical degradation rates, corrupting the validity of conventional degradation tests. Here we report an ex vivo vascular bioreactor, which allows simulation of the microenvironment with and without blood vessel integration to study the biodegradation of magnesium implants in comparison with standard in vitro test conditions and with in vivo implantations. The bioreactor did simulate the corrosion of an intramural implant very well, but

  18. Saccharomyces cerevisiae gene expression changes during rotating wall vessel suspension culture

    NASA Technical Reports Server (NTRS)

    Johanson, Kelly; Allen, Patricia L.; Lewis, Fawn; Cubano, Luis A.; Hyman, Linda E.; Hammond, Timothy G.

    2002-01-01

    This study utilizes Saccharomyces cerevisiae to study genetic responses to suspension culture. The suspension culture system used in this study is the high-aspect-ratio vessel, one type of the rotating wall vessel, that provides a high rate of gas exchange necessary for rapidly dividing cells. Cells were grown in the high-aspect-ratio vessel, and DNA microarray and metabolic analyses were used to determine the resulting changes in yeast gene expression. A significant number of genes were found to be up- or downregulated by at least twofold as a result of rotational growth. By using Gibbs promoter alignment, clusters of genes were examined for promoter elements mediating these genetic changes. Candidate binding motifs similar to the Rap1p binding site and the stress-responsive element were identified in the promoter regions of differentially regulated genes. This study shows that, as in higher order organisms, S. cerevisiae changes gene expression in response to rotational culture and also provides clues for investigations into the signaling pathways involved in gravitational response.

  19. Saccharomyces cerevisiae gene expression changes during rotating wall vessel suspension culture

    NASA Technical Reports Server (NTRS)

    Johanson, Kelly; Allen, Patricia L.; Lewis, Fawn; Cubano, Luis A.; Hyman, Linda E.; Hammond, Timothy G.

    2002-01-01

    This study utilizes Saccharomyces cerevisiae to study genetic responses to suspension culture. The suspension culture system used in this study is the high-aspect-ratio vessel, one type of the rotating wall vessel, that provides a high rate of gas exchange necessary for rapidly dividing cells. Cells were grown in the high-aspect-ratio vessel, and DNA microarray and metabolic analyses were used to determine the resulting changes in yeast gene expression. A significant number of genes were found to be up- or downregulated by at least twofold as a result of rotational growth. By using Gibbs promoter alignment, clusters of genes were examined for promoter elements mediating these genetic changes. Candidate binding motifs similar to the Rap1p binding site and the stress-responsive element were identified in the promoter regions of differentially regulated genes. This study shows that, as in higher order organisms, S. cerevisiae changes gene expression in response to rotational culture and also provides clues for investigations into the signaling pathways involved in gravitational response.

  20. Neuropeptide degradation by large vessel and microvessel-derived endothelial cells in vitro: cell surface catabolism of thyrotropin releasing hormone (TRH).

    PubMed

    Rozental, J M; Kaminska, G; Turner, J; Schwartz, T; Cadahia, V; Brooks, B R

    1989-10-16

    Cell surface ectopeptidase activity of purified, cultured large vessel and microvessel-derived endothelial cells (EC) was studied. Degradation of thyrotropin releasing hormone (TRH), and production of cyclo-His-Pro was significantly increased (P less than 0.001) in large vessel EC compared with microcapillary EC. Since the rate of catabolism in the microvascular capillary bed is 5 times less than that in the large vessel wall, peptide concentrations are likely maintained longer in close proximity to their site of biosynthesis, where they are presumably most active.

  1. Platelets As Initiators and Mediators of Inflammation at the Vessel Wall

    PubMed Central

    Shi, Guanfang; Morrell, Craig N.

    2010-01-01

    Platelets are dynamic cells with activities that extend beyond thrombosis including an important role in initiating and sustaining vascular inflammation. A role for platelets has been described in many physiologic and pathophysiologic processes such as atherosclerosis, stem cell trafficking, tumor metastasis, and arthritis. Platelet activation at sites of an intact inflamed endothelium contributes to vascular inflammation and vascular wall remodeling. Platelets secrete a wide array of preformed and synthesized inflammatory mediators upon activation that can exert significant local and systemic effects. This review will focus on the role of platelet derived mediators in vascular inflammation and vascular wall remodeling. PMID:21094986

  2. Estimation of the viscoelastic properties of vessel walls using a computational model and Doppler ultrasound

    NASA Astrophysics Data System (ADS)

    Balocco, Simone; Basset, Olivier; Courbebaisse, Guy; Boni, Enrico; Frangi, Alejandro F.; Tortoli, Piero; Cachard, Christian

    2010-06-01

    Human arteries affected by atherosclerosis are characterized by altered wall viscoelastic properties. The possibility of noninvasively assessing arterial viscoelasticity in vivo would significantly contribute to the early diagnosis and prevention of this disease. This paper presents a noniterative technique to estimate the viscoelastic parameters of a vascular wall Zener model. The approach requires the simultaneous measurement of flow variations and wall displacements, which can be provided by suitable ultrasound Doppler instruments. Viscoelastic parameters are estimated by fitting the theoretical constitutive equations to the experimental measurements using an ARMA parameter approach. The accuracy and sensitivity of the proposed method are tested using reference data generated by numerical simulations of arterial pulsation in which the physiological conditions and the viscoelastic parameters of the model can be suitably varied. The estimated values quantitatively agree with the reference values, showing that the only parameter affected by changing the physiological conditions is viscosity, whose relative error was about 27% even when a poor signal-to-noise ratio is simulated. Finally, the feasibility of the method is illustrated through three measurements made at different flow regimes on a cylindrical vessel phantom, yielding a parameter mean estimation error of 25%.

  3. Estimation of the viscoelastic properties of vessel walls using a computational model and Doppler ultrasound.

    PubMed

    Balocco, Simone; Basset, Olivier; Courbebaisse, Guy; Boni, Enrico; Frangi, Alejandro F; Tortoli, Piero; Cachard, Christian

    2010-06-21

    Human arteries affected by atherosclerosis are characterized by altered wall viscoelastic properties. The possibility of noninvasively assessing arterial viscoelasticity in vivo would significantly contribute to the early diagnosis and prevention of this disease. This paper presents a noniterative technique to estimate the viscoelastic parameters of a vascular wall Zener model. The approach requires the simultaneous measurement of flow variations and wall displacements, which can be provided by suitable ultrasound Doppler instruments. Viscoelastic parameters are estimated by fitting the theoretical constitutive equations to the experimental measurements using an ARMA parameter approach. The accuracy and sensitivity of the proposed method are tested using reference data generated by numerical simulations of arterial pulsation in which the physiological conditions and the viscoelastic parameters of the model can be suitably varied. The estimated values quantitatively agree with the reference values, showing that the only parameter affected by changing the physiological conditions is viscosity, whose relative error was about 27% even when a poor signal-to-noise ratio is simulated. Finally, the feasibility of the method is illustrated through three measurements made at different flow regimes on a cylindrical vessel phantom, yielding a parameter mean estimation error of 25%.

  4. Analysis of HRCT-derived xylem network reveals reverse flow in some vessels

    USDA-ARS?s Scientific Manuscript database

    Flow in xylem vessels is modeled based on constructions of three dimensional xylem networks derived from High Resolution Computed Tomography (HRCT) images of grapevine (Vitis vinifera) stems. Flow in 6-14% of the vessels was found to be oriented in the opposite direction to the bulk flow under norma...

  5. Domain walls and ferroelectric reversal in corundum derivatives

    NASA Astrophysics Data System (ADS)

    Ye, Meng; Vanderbilt, David

    2017-01-01

    Domain walls are the topological defects that mediate polarization reversal in ferroelectrics, and they may exhibit quite different geometric and electronic structures compared to the bulk. Therefore, a detailed atomic-scale understanding of the static and dynamic properties of domain walls is of pressing interest. In this work, we use first-principles methods to study the structures of 180∘ domain walls, both in their relaxed state and along the ferroelectric reversal pathway, in ferroelectrics belonging to the family of corundum derivatives. Our calculations predict their orientation, formation energy, and migration energy and also identify important couplings between polarization, magnetization, and chirality at the domain walls. Finally, we point out a strong empirical correlation between the height of the domain-wall-mediated polarization reversal barrier and the local bonding environment of the mobile A cations as measured by bond-valence sums. Our results thus provide both theoretical and empirical guidance for future searches for ferroelectric candidates in materials of the corundum derivative family.

  6. Vessel wall signal enhancement on 3-T MRI in acute stroke patients after stent retriever thrombectomy.

    PubMed

    Abraham, Peter; Scott Pannell, J; Santiago-Dieppa, David R; Cheung, Vincent; Steinberg, Jeffrey; Wali, Arvin; Gupta, Mihir; Rennert, Robert C; Lee, Roland R; Khalessi, Alexander A

    2017-04-01

    OBJECTIVE In vivo and in vitro studies have demonstrated histological evidence of iatrogenic endothelial injury after stent retriever thrombectomy. However, noncontrast vessel wall (VW)-MRI is insufficient to demonstrate vessel injury. Authors of this study prospectively evaluated iatrogenic endothelial damage after stent retriever thrombectomy in humans by utilizing high-resolution contrast-enhanced VW-MRI. Characterization of VW-MRI changes in vessels subject to mechanical injury from thrombectomy may allow better understanding of the biological effects of this intervention. METHODS The authors prospectively recruited 11 patients for this study. The treatment group included 6 postthrombectomy patients and the control group included 5 subjects undergoing MRI for nonvascular indications. All subjects were evaluated on a Signa HD× 3.0-T MRI scanner with an 8-channel head coil. Both pre- and postcontrast T1-weighted Cube VW images as well as MR angiograms were acquired. Sequences obtained for evaluation of the brain parenchyma included diffusion-weighted, gradient echo, and T2-FLAIR imaging. Two independent neuroradiologists, who were blinded to the treatment status of each patient, determined the presence of VW enhancement. Patient age, National Institutes of Health Stroke Scale score on presentation, location of occlusion, stroke etiology, type of device used, number of device deployments, Thrombolysis in Cerebral Infarction (TICI) reperfusion score, stroke volume, and 90-day modified Rankin Scale score were also noted. RESULTS Postcontrast T1-weighted VW enhancement was detected in the M2 segment in 100% of the thrombectomy patients, in the M1 segment in 83%, and in the internal carotid artery in 50%. One patient also demonstrated A1 segment enhancement, which was attributable to thrombectomy treatment of that vessel segment during the same procedure. None of the control patients demonstrated VW enhancement of their intracranial vasculature on T1-weighted images

  7. Intracranial plaque enhancement from high resolution vessel wall magnetic resonance imaging predicts stroke recurrence.

    PubMed

    Kim, Jeong-Min; Jung, Keun-Hwa; Sohn, Chul-Ho; Moon, Jangsup; Shin, Jung-Hwan; Park, Jaeseok; Lee, Seung-Hoon; Han, Moon Hee; Roh, Jae-Kyu

    2016-02-01

    Intracranial atherosclerosis is associated with frequent stroke recurrence. High resolution vessel wall magnetic resonance imaging (HRMRI) can provide atheroma information related to its vulnerability. We performed HRMRI in stroke patients with intracranial atherosclerosis to determine whether plaque characteristics from vessel wall imaging can predict future stroke recurrence. Between July 2011 and June 2013, acute stroke patients with symptomatic intracranial atherosclerosis were prospectively enrolled and 3-tesla HRMRI was performed on the relevant artery. The plaque enhancement was visually determined from T1 post-gadolinium enhancement image. Stroke recurrence was monitored after index event and multivariate Cox proportional hazards model was constructed to identify factors related to future stroke recurrence. A total of 138 patients were included with a median follow-up of 18 months. There were 39 stroke recurrences. Plaque enhancement was detected in 108 patients (78.3%), and 37 of them experienced stroke recurrence. Among 30 stroke patients without plaque enhancement, two patients experienced stroke recurrence. Kaplan-Meier curves demonstrated a significant difference in event free survival between the patients with plaque enhancement and those patients without plaque enhancement (event rates at year 1: 30.3% vs. 6.8%, log-rank test, p = 0.004). Multivariate Cox-regression analysis showed that the plaque enhancement from HRMRI was independently associated with stroke recurrence (hazard ratio: 7.42, 95% confidence interval: 1.74-31.75, p = 0.007). Intracranial plaque enhancement from HRMRI is associated with stroke recurrence among the patients with symptomatic intracranial atherosclerosis. © 2016 World Stroke Organization.

  8. Improved black-blood imaging using DANTE-SPACE for simultaneous carotid and intracranial vessel wall evaluation

    PubMed Central

    Xie, Yibin; Yang, Qi; Xie, Guoxi; Pang, Jianing; Fan, Zhaoyang; Li, Debiao

    2015-01-01

    Purpose The purpose of this work is to develop a 3D black-blood imaging method for simultaneously evaluating carotid and intracranial arterial vessel wall with high spatial resolution and excellent blood suppression with and without contrast enhancement. Methods DANTE preparation module was incorporated into SPACE sequence to improve blood signal suppression. Simulations and phantom studies were performed to quantify image contrast variations induced by DANTE. DANTE-SPACE, SPACE and 2D TSE were compared for apparent SNR, CNR and morphometric measurements in fourteen healthy subjects. Preliminary clinical validation was performed in six symptomatic patients. Results Apparent residual luminal blood was observed in 5 (pre-CE) and 9 (post-CE) subjects with SPACE, and only 2 (post-CE) subjects with DANTE-SPACE. DANTE-SPACE showed 31% (pre-CE) and 100% (post-CE) improvement in wall-to-blood CNR over SPACE. Vessel wall area measured from SPACE was significantly larger than that from DANTE-SPACE due to possible residual blood signal contamination. In patients DANTE-SPACE showed the potential to detect vessel wall dissection and identify plaque components. Conclusion DANTE-SPACE significantly improved arterial and venous blood suppression compared with SPACE. Simultaneous high-resolution carotid and intracranial vessel wall imaging to potentially identify plaque components was feasible with scan time under 6 minutes. PMID:26152900

  9. Mechanisms of ATP release and signalling in the blood vessel wall

    PubMed Central

    Lohman, Alexander W.; Billaud, Marie; Isakson, Brant E.

    2012-01-01

    The nucleotide adenosine 5′-triphosphate (ATP) has classically been considered the cell's primary energy currency. Importantly, a novel role for ATP as an extracellular autocrine and/or paracrine signalling molecule has evolved over the past century and extensive work has been conducted to characterize the ATP-sensitive purinergic receptors expressed on almost all cell types in the body. Extracellular ATP elicits potent effects on vascular cells to regulate blood vessel tone but can also be involved in vascular pathologies such as atherosclerosis. While the effects of purinergic signalling in the vasculature have been well documented, the mechanism(s) mediating the regulated release of ATP from cells in the blood vessel wall and circulation are now a key target of investigation. The aim of this review is to examine the current proposed mechanisms of ATP release from vascular cells, with a special emphasis on the transporters and channels involved in ATP release from vascular smooth muscle cells, endothelial cells, circulating red blood cells, and perivascular sympathetic nerves, including vesicular exocytosis, plasma membrane F1/F0-ATP synthase, ATP-binding cassette (ABC) transporters, connexin hemichannels, and pannexin channels. PMID:22678409

  10. Fracture resistance of welded thick-walled high-pressure vessels in power plants. Report No. 1. Statistical analysis of defects and fracture resistance of vessel materials

    SciTech Connect

    Gorynin, I.V.; Filatov, V.M.; Ignatov, V.A.; Timofeev, B.T.; Zvezdin, Yu. I.

    1986-07-01

    Data from plant radiographic inspection of reactor vessels and boilers in power plants of 440- and 1000-MW capacity were subjected to statistical analysis. It was found that, given the current technology for making and constructing 440- and 1000-MW power plants, the limiting defect size in the vessels of the plants is no more than 10% of the wall thickness according to the results of statistical analysis. This finding makes it possible to increase the tolerable stresses by a factor of 1.6 compared to the current estimate of resistance to brittle fracture, which presumes the presence of a semielliptical surface crack of a depth corresponding to 25% of the wall thickness. The fracture resistance of steel increase with a decrease in defect size and as a result of the damping capacity of the anticorrosive hardfacing applied.

  11. Rupture Properties of Blood Vessel Walls Measured by Pressure-Imposed Test

    NASA Astrophysics Data System (ADS)

    Ohashi, Toshiro; Sugita, Syukei; Matsumoto, Takeo; Kumagai, Kiichiro; Akimoto, Hiroji; Tabayashi, Koichi; Sato, Masaaki

    It is expected to be clinically useful to know the mechanical properties of human aortic aneurysms in assessing the potential for aneurysm rupture. For this purpose, a newly designed experimental setup was fabricated to measure the rupture properties of blood vessel walls. A square specimen of porcine thoracic aortas is inflated by air pressure at a rate of 10mmHg/s (≈1.3MPa/s) until rupture occurs. Mean breaking stress was 1.8±0.4 MPa (mean±SD) for the specimens proximal to the heart and 2.3±0.8MPa for the distal specimens, which are not significantly different to those values obtained longitudinally from conventional tensile tests. Moreover, the local breaking stretch ratio in the longitudinal direction was significantly higher at the ruptured site (2.7±0.5) than at the unruptured site (2.2±0.4). This testing system for studying the rupture properties of aortic walls is expected to be applicable to aortic aneurysms. Experimental verification of the present technique for the homogeneous, isotropic material is also presented.

  12. Identification of vessel wall degradation in ascending thoracic aortic aneurysms with OCT

    PubMed Central

    Real, Eusebio; Val-Bernal, José Fernando; Revuelta, José M.; Pontón, Alejandro; Díez, Marta Calvo; Mayorga, Marta; López-Higuera, José M.; Conde, Olga M.

    2014-01-01

    Degradation of the wall of human ascending thoracic aorta has been assessed through Optical Coherence Tomography (OCT). OCT images of the media layer of the aortic wall exhibit micro-structure degradation in case of diseased aortas from aneurysmal vessels. The OCT indicator of degradation depends on the dimension of areas of the media layer where backscattered reflectivity becomes smaller due to a disorder on the morphology of elastin, collagen and smooth muscle cells (SMCs). Efficient pre-processing of the OCT images is required to accurately extract the dimension of degraded areas after an optimized thresholding procedure. OCT results have been validated against conventional histological analysis. The OCT qualitative assessment has achieved a pair sensitivity-specificity of 100%-91.6% in low-high degradation discrimination when a threshold of 4965.88µm2 is selected. This threshold suggests to have physiological meaning. The OCT quantitative evaluation of degradation achieves a correlation of 0.736 between the OCT indicator and the histological score. This in-vitro study can be transferred to the clinical scenario to provide an intraoperative assessment tool to guide cardiovascular surgeons in open repair interventions. PMID:25426332

  13. Endothelial Expression of Guidance Cues in Vessel Wall Homeostasis: Dysregulation under pro-atherosclerotic conditions

    PubMed Central

    van Gils, Janine M.; Ramkhelawon, Bhama; Fernandes, Luciana; Stewart, Merran C.; Guo, Liang; Seibert, Tara; Menezes, Gustavo B.; Cara, Denise C.; Chow, Camille; Kinane, T. Bernard; Fisher, Edward A.; Balcells, Mercedes; Alvarez-Leite, Jacqueline; Moore, Kathryn J.

    2013-01-01

    Objective Emerging evidence suggests that neuronal guidance cues, typically expressed during development, are involved in both physiological and pathological immune responses. We hypothesized that endothelial expression of such guidance cues may regulate leukocyte trafficking into the vascular wall during atherogenesis. Approach/Results We demonstrate that members of the Netrin, Semaphorin and Ephrin family of guidance molecules are differentially regulated under conditions that promote or protect from atherosclerosis. Netrin-1 and Semaphorin3A are expressed by coronary artery endothelial cells and potently inhibit chemokine-directed migration of human monocytes. Endothelial expression of these negative guidance cues is down-regulated by pro-atherogenic factors, including oscillatory shear stress and pro-inflammatory cytokines associated with monocyte entry into the vessel wall. Furthermore, we show using intravital microscopy that inhibition of Netrin-1 or Semaphorin3A using blocking peptides increases leukocyte adhesion to the endothelium. Unlike Netrin-1 and Semaphorin3A, the guidance cue EphrinB2 is up-regulated under pro-atherosclerotic flow conditions and functions as a chemoattractant, increasing leukocyte migration in the absence of additional chemokines. Conclusions The concurrent regulation of negative and positive guidance cues may facilitate leukocyte infiltration of the endothelium through a balance between chemoattraction and chemorepulsion. These data indicate a previously unappreciated role for axonal guidance cues in maintaining the endothelial barrier and regulating leukocyte trafficking during atherogenesis. PMID:23430612

  14. Vessel wall MRI to differentiate between reversible cerebral vasoconstriction syndrome and central nervous system vasculitis: preliminary results.

    PubMed

    Mandell, Daniel M; Matouk, Charles C; Farb, Richard I; Krings, Timo; Agid, Ronit; terBrugge, Karel; Willinsky, Robert A; Swartz, Richard H; Silver, Frank L; Mikulis, David J

    2012-03-01

    Prospective differentiation between reversible cerebral vasoconstriction syndrome and central nervous system vasculitis can be challenging. We hypothesized that high-resolution vessel wall MRI would demonstrate arterial wall enhancement in central nervous system vasculitis but not in reversible cerebral vasoconstriction syndrome. We identified all patients with multifocal segmental narrowing of large intracranial arteries who had high-resolution vessel wall MRI and follow-up angiography at our institute over a 4-year period and performed a detailed chart review. Three patients lacked arterial wall enhancement, and these all had reversal of arterial narrowing within 3 months. Four patients demonstrated arterial wall enhancement, and these had persistent or progressive arterial narrowing at a median follow-up of 17 months (range, 6-36 months) with final diagnoses of central nervous system vasculitis (3) and cocaine vasculopathy (1). Preliminary results suggest that high-resolution contrast-enhanced vessel wall MRI may enable differentiation between reversible cerebral vasoconstriction syndrome and central nervous system vasculitis.

  15. Feasibility of 18F-fluoromethylcholine PET/CT for imaging of vessel wall alterations in humans--first results.

    PubMed

    Bucerius, Jan; Schmaljohann, Jörn; Böhm, Ingrid; Palmedo, Holger; Guhlke, Stefan; Tiemann, Klaus; Schild, Hans Heinz; Biersack, Hans-Jürgen; Manka, Christoph

    2008-04-01

    Recently published data indicated (18)F-fluorocholine to be feasible for imaging vulnerable atherosclerotic plaques in an animal model. Five patients undergoing whole-body (18)F-fluoromethylcholine-((18)F-FMCH-) PET/CT for imaging of prostate cancer disease were retrospectively evaluated. Whole-body PET scans were started immediately after i.v. injection of (18)F-FMCH. About 5-15 min after tracer injection, acquisition of scans of the pelvis and abdomen was performed. PET, CT, and PET/CT slices were generated for review and visual analyses of the abdominal aorta and the common iliac arteries were performed. Vascular findings in examined arteries and surrounding structures due to artifacts were excluded from further analysis. The lower threshold of (18)F-FMCH uptake was set above the background activity within the examined vessels. Morphological classification of vessel wall alterations (WA) included structural wall alterations without additional calcification (SWA), structural wall alterations associated with calcifications (SWC), and solely calcified lesions (CL). They were correlated with (18)F-FMCH uptake qualified as present and vice versa. A total of 31 WA were identified. Positive (18)F-FMCH uptake was found in 14 lesions (SWA: n = 5; SWC: n = 9). Sixteen of 17 (18)F-FMCH negative lesions were identified as CL without additional structural vessel wall alteration. One SWA did not show any (18)F-FMCH accumulation. None of the CLs as well as unaltered parts of the vessel wall showed (18)F-FMCH uptake. Our initial data in five patients with a total of 31 vessel wall alterations show promising results indicating for the first time the feasibility of (18)F-FMCH for in vivo imaging of structural WA in humans.

  16. Combined coronary lumen and vessel wall magnetic resonance imaging with i-T2prep: influence of nitroglycerin.

    PubMed

    Hussain, Tarique; Henningsson, Markus; Butzbach, Britta; Lossnitzer, Dirk; Greil, Gerald F; Andia, Marcelo E; Botnar, Rene M

    2015-01-01

    It has been shown that sublingual nitroglycerin (NTG) improves image quality of coronary lumen magnetic resonance angiography. Our aim was to investigate the influence of NTG on coronary lumen and vessel wall image quality using a combined, single sequence approach (i-T2prep), which is able to image both within the known time frame of action of NTG. Ten healthy volunteers underwent right coronary artery lumen and vessel wall imaging using the i-T2prep sequence before and after administration of NTG. Image quality was assessed qualitatively and quantitatively. Diameter, length and wall thickness were also measured using dedicated semi-automatic software. NTG induced coronary vasodilatation (lumen diameter increased from 2.16 ± 0.32 to 2.52 ± 0.59 mm; p = 0.036). As a result, visualized lumen length (9.8 ± 2.6 to 11.4 ± 3.3 cm; p = 0.025) and qualitative lumen image quality (median 3 (interquartile range 2-3.25) vs. median 3 (interquartile range 3-4); p = 0.046) both improved. Vessel wall imaging also demonstrated a significant improvement in vessel wall sharpness after NTG (24.8 vs. 27.3 %; p = 0.036). This study demonstrates the benefits of NTG for coronary lumen and vessel wall imaging using a combined sequence, i-T2prep. The methodology described here has great potential for future pathophysiological studies.

  17. Ethacrynic acid rapidly and selectively abolishes blood flow in vessels supplying the lateral wall of the cochlea.

    PubMed

    Ding, Dalian; McFadden, Sandra L; Woo, Jenifer M; Salvi, Richard J

    2002-11-01

    The mechanisms underlying the ototoxicity of ethacrynic acid (EA) are not fully understood. Previous studies have focused on morphologic and enzymatic changes in the stria vascularis. The current experiment shows that one of the earliest effects of EA is ischemia, resulting from impaired blood flow in vessels supplying the lateral wall of the cochlea. Inner ear microcirculation, endocochlear potentials, compound action potentials (CAP), cochlear microphonics (CM) and summating potentials (SP) were monitored over time in chinchillas following a single injection of EA (40 mg/kg i.v.). At all times after EA injection, blood vessels supplying the spiral lamina, modiolus, and vestibular end organs appeared normal. In contrast, lateral wall (spiral ligament and stria vascularis) vessels were poorly stained with eosin 2 min after EA injection, and devoid of red blood cells at 30 min post EA. Decline, but not recovery, of CAP, CM and SP followed the microcirculation changes in the lateral wall. Reperfusion was delayed in stria vascularis arterioles relative to other lateral wall vessels. The ischemia-reperfusion caused by EA would be expected to generate large quantities of free radicals, which may trigger or contribute to the cellular, enzymatic, and functional pathologies that have been described in detail previously.

  18. Preservation of quadrature Doppler signals from bidirectional slow blood flow close to the vessel wall using an adaptive decomposition algorithm.

    PubMed

    Zhang, Yufeng; Shi, Xinling; Zhang, Kexin; Chen, Jianhua

    2009-03-01

    A novel approach based on the phasing-filter (PF) technique and the empirical mode decomposition (EMD) algorithm is proposed to preserve quadrature Doppler signal components from bidirectional slow blood flow close to the vessel wall. Bidirectional mixed Doppler ultrasound signals, which were echoed from the forward and reverse moving blood and vessel wall, were initially separated to avoid the phase distortion of quadrature Doppler signals (which is induced from direct decomposition by the nonlinear EMD processing). Separated unidirectional mixed Doppler signals were decomposed into intrinsic mode functions (IMFs) using the EMD algorithm and the relevant IMFs that contribute to blood flow components were identified and summed to give the blood flow signals, whereby only the components from the bidirectional slow blood flow close to the vessel wall were retained independently. The complex quadrature Doppler blood flow signal was reconstructed from a combination of the extracted unidirectional Doppler blood flow signals. The proposed approach was applied to simulated and clinical Doppler signals. It is concluded from the experimental results that this approach is practical for the preservation of quadrature Doppler signal components from the bidirectional slow blood flow close to the vessel wall, and may provide more diagnostic information for the diagnosis and treatment of vascular diseases.

  19. Analysis of HRCT-derived xylem network reveals reverse flow in some vessels.

    PubMed

    Lee, Eric F; Matthews, Mark A; McElrone, Andrew J; Phillips, Ronald J; Shackel, Kenneth A; Brodersen, Craig R

    2013-09-21

    Long distance water and nutrient transport in plants is dependent on the proper functioning of xylem networks, a series of interconnected pipe-like cells that are vulnerable to hydraulic dysfunction as a result of drought-induced embolism and/or xylem-dwelling pathogens. Here, flow in xylem vessels was modeled to determine the role of vessel connectivity by using three dimensional xylem networks derived from High Resolution Computed Tomography (HRCT) images of grapevine (Vitis vinifera cv. 'Chardonnay') stems. Flow in 4-27% of the vessel segments (i.e. any section of vessel elements between connection points associated with intervessel pits) was found to be oriented in the direction opposite to the bulk flow under normal transpiration conditions. In order for the flow in a segment to be in the reverse direction, specific requirements were determined for the location of connections, distribution of vessel endings, diameters of the connected vessels, and the conductivity of the connections. Increasing connectivity and decreasing vessel length yielded increasing numbers of reverse flow segments until a maximum value was reached, after which more interconnected networks and smaller average vessel lengths yielded a decrease in the number of reverse flow segments. Xylem vessel relays also encouraged the formation of reverse flow segments. Based on the calculated flow rates in the xylem network, the downward spread of Xylella fastidiosa bacteria in grape stems was modeled, and reverse flow was shown to be an additional mechanism for the movement of bacteria to the trunk of grapevine.

  20. Automated registration of multispectral MR vessel wall images of the carotid artery

    SciTech Connect

    Klooster, R. van 't; Staring, M.; Reiber, J. H. C.; Lelieveldt, B. P. F.; Geest, R. J. van der; Klein, S.; Kwee, R. M.; Kooi, M. E.

    2013-12-15

    Purpose: Atherosclerosis is the primary cause of heart disease and stroke. The detailed assessment of atherosclerosis of the carotid artery requires high resolution imaging of the vessel wall using multiple MR sequences with different contrast weightings. These images allow manual or automated classification of plaque components inside the vessel wall. Automated classification requires all sequences to be in alignment, which is hampered by patient motion. In clinical practice, correction of this motion is performed manually. Previous studies applied automated image registration to correct for motion using only nondeformable transformation models and did not perform a detailed quantitative validation. The purpose of this study is to develop an automated accurate 3D registration method, and to extensively validate this method on a large set of patient data. In addition, the authors quantified patient motion during scanning to investigate the need for correction. Methods: MR imaging studies (1.5T, dedicated carotid surface coil, Philips) from 55 TIA/stroke patients with ipsilateral <70% carotid artery stenosis were randomly selected from a larger cohort. Five MR pulse sequences were acquired around the carotid bifurcation, each containing nine transverse slices: T1-weighted turbo field echo, time of flight, T2-weighted turbo spin-echo, and pre- and postcontrast T1-weighted turbo spin-echo images (T1W TSE). The images were manually segmented by delineating the lumen contour in each vessel wall sequence and were manually aligned by applying throughplane and inplane translations to the images. To find the optimal automatic image registration method, different masks, choice of the fixed image, different types of the mutual information image similarity metric, and transformation models including 3D deformable transformation models, were evaluated. Evaluation of the automatic registration results was performed by comparing the lumen segmentations of the fixed image and

  1. Automated registration of multispectral MR vessel wall images of the carotid artery

    SciTech Connect

    Klooster, R. van 't; Staring, M.; Reiber, J. H. C.; Lelieveldt, B. P. F.; Geest, R. J. van der; Klein, S.; Kwee, R. M.; Kooi, M. E.

    2013-12-15

    Purpose: Atherosclerosis is the primary cause of heart disease and stroke. The detailed assessment of atherosclerosis of the carotid artery requires high resolution imaging of the vessel wall using multiple MR sequences with different contrast weightings. These images allow manual or automated classification of plaque components inside the vessel wall. Automated classification requires all sequences to be in alignment, which is hampered by patient motion. In clinical practice, correction of this motion is performed manually. Previous studies applied automated image registration to correct for motion using only nondeformable transformation models and did not perform a detailed quantitative validation. The purpose of this study is to develop an automated accurate 3D registration method, and to extensively validate this method on a large set of patient data. In addition, the authors quantified patient motion during scanning to investigate the need for correction. Methods: MR imaging studies (1.5T, dedicated carotid surface coil, Philips) from 55 TIA/stroke patients with ipsilateral <70% carotid artery stenosis were randomly selected from a larger cohort. Five MR pulse sequences were acquired around the carotid bifurcation, each containing nine transverse slices: T1-weighted turbo field echo, time of flight, T2-weighted turbo spin-echo, and pre- and postcontrast T1-weighted turbo spin-echo images (T1W TSE). The images were manually segmented by delineating the lumen contour in each vessel wall sequence and were manually aligned by applying throughplane and inplane translations to the images. To find the optimal automatic image registration method, different masks, choice of the fixed image, different types of the mutual information image similarity metric, and transformation models including 3D deformable transformation models, were evaluated. Evaluation of the automatic registration results was performed by comparing the lumen segmentations of the fixed image and

  2. Regulator of G-protein signaling 5 controls blood pressure homeostasis and vessel wall remodeling.

    PubMed

    Holobotovskyy, Vasyl; Manzur, Mitali; Tare, Marianne; Burchell, Jennifer; Bolitho, Erin; Viola, Helena; Hool, Livia C; Arnolda, Leonard F; McKitrick, Douglas J; Ganss, Ruth

    2013-03-01

    Regulator of G-protein signaling 5 (RGS5) modulates G-protein-coupled receptor signaling and is prominently expressed in arterial smooth muscle cells. Our group first reported that RGS5 is important in vascular remodeling during tumor angiogenesis. We hypothesized that RGS5 may play an important role in vessel wall remodeling and blood pressure regulation. To demonstrate that RGS5 has a unique and nonredundant role in the pathogenesis of hypertension and to identify crucial RGS5-regulated signaling pathways. We observed that arterial RGS5 expression is downregulated with chronically elevated blood pressure after angiotensin II infusion. Using a knockout mouse model, radiotelemetry, and pharmacological inhibition, we subsequently showed that loss of RGS5 results in profound hypertension. RGS5 signaling is linked to the renin-angiotensin system and directly controls vascular resistance, vessel contractility, and remodeling. RGS5 deficiency aggravates pathophysiological features of hypertension, such as medial hypertrophy and fibrosis. Moreover, we demonstrate that protein kinase C, mitogen-activated protein kinase/extracellular signal-regulated kinase, and Rho kinase signaling pathways are major effectors of RGS5-mediated hypertension. Loss of RGS5 results in hypertension. Loss of RGS5 signaling also correlates with hyper-responsiveness to vasoconstrictors and vascular stiffening. This establishes a significant, distinct, and causal role of RGS5 in vascular homeostasis. RGS5 modulates signaling through the angiotensin II receptor 1 and major Gαq-coupled downstream pathways, including Rho kinase. So far, activation of RhoA/Rho kinase has not been associated with RGS molecules. Thus, RGS5 is a crucial regulator of blood pressure homeostasis with significant clinical implications for vascular pathologies, such as hypertension.

  3. On-site implementation of characterization and sizing techniques for outer-wall defects in reactor pressure vessels

    SciTech Connect

    Lasserre, F.; Chapuis, N.

    1994-12-31

    Pressurized reactor vessels in France have been examined from the inside with ultrasonic focused transducers since the very first inspection. The developments carried out to solve the problem of oversizing in the case of defects located near the outer surface in the welds or in the wall thickness and presented in the framework of the 10th and 11th conference of NDE in the nuclear and pressure vessels industries, now have applications through SPARTACUS software work. Indications detected during, the systematic inspection of welds and shells, corresponding to outer wall defects, trigger a digital acquisition of data, the scanning being limited to the area of interest. This acquisition is now followed by analysis through the new system CIVAMIS, which includes the main imaging tools of SPARTACUS, but which has been specifically developed to be implemented on site, for outer wall defects. Characteristics of CIVAMIS in relation with the initial structure of SPARTACUS are discussed on actual results.

  4. Bobbin-Tool Friction-Stir Welding of Thick-Walled Aluminum Alloy Pressure Vessels

    SciTech Connect

    Dalder, E C; Pastrnak, J W; Engel, J; Forrest, R S; Kokko, E; Ternan, K M; Waldron, D

    2007-06-06

    It was desired to assemble thick-walled Al alloy 2219 pressure vessels by bobbin-tool friction-stir welding. To develop the welding-process, mechanical-property, and fitness-for-service information to support this effort, extensive friction-stir welding-parameter studies were conducted on 2.5 cm. and 3.8 cm. thick 2219 Al alloy plate. Starting conditions of the plate were the fully-heat-treated (-T62) and in the annealed (-O) conditions. The former condition was chosen with the intent of using the welds in either the 'as welded' condition or after a simple low-temperature aging treatment. Since preliminary stress-analyses showed that stresses in and near the welds would probably exceed the yield-strength of both 'as welded' and welded and aged weld-joints, a post-weld solution-treatment, quenching, and aging treatment was also examined. Once a suitable set of welding and post-weld heat-treatment parameters was established, the project divided into two parts. The first part concentrated on developing the necessary process information to be able to make defect-free friction-stir welds in 3.8 cm. thick Al alloy 2219 in the form of circumferential welds that would join two hemispherical forgings with a 102 cm. inside diameter. This necessitated going to a bobbin-tool welding-technique to simplify the tooling needed to react the large forces generated in friction-stir welding. The bobbin-tool technique was demonstrated on both flat-plates and plates that were bent to the curvature of the actual vessel. An additional issue was termination of the weld, i.e. closing out the hole left at the end of the weld by withdrawal of the friction-stir welding tool. This was accomplished by friction-plug welding a slightly-oversized Al alloy 2219 plug into the termination-hole, followed by machining the plug flush with both the inside and outside surfaces of the vessel. The second part of the project involved demonstrating that the welds were fit for the intended service. This

  5. Rotating wall vessel exposure alters protein secretion and global gene expression in Staphylococcus aureus

    NASA Astrophysics Data System (ADS)

    Rosado, Helena; O'Neill, Alex J.; Blake, Katy L.; Walther, Meik; Long, Paul F.; Hinds, Jason; Taylor, Peter W.

    2012-04-01

    Staphylococcus aureus is routinely recovered from air and surface samples taken aboard the International Space Station (ISS) and poses a health threat to crew. As bacteria respond to the low shear forces engendered by continuous rotation conditions in a Rotating Wall Vessel (RWV) and the reduced gravitational field of near-Earth flight by altering gene expression, we examined the effect of low-shear RWV growth on protein secretion and gene expression by three S. aureus isolates. When cultured under 1 g, the total amount of protein secreted by these strains varied up to fourfold; under continuous rotation conditions, protein secretion by all three strains was significantly reduced. Concentrations of individual proteins were differentially reduced and no evidence was found for increased lysis. These data suggest that growth under continuous rotation conditions reduces synthesis or secretion of proteins. A limited number of changes in gene expression under continuous rotation conditions were noted: in all isolates vraX, a gene encoding a polypeptide associated with cell wall stress, was down-regulated. A vraX deletion mutant of S. aureus SH1000 was constructed: no differences were found between SH1000 and ΔvraX with respect to colony phenotype, viability, protein export, antibiotic susceptibility, vancomycin kill kinetics, susceptibility to cold or heat and gene modulation. An ab initio protein-ligand docking simulation suggests a major binding site for β-lactam drugs such as imipenem. If such changes to the bacterial phenotype occur during spaceflight, they will compromise the capacity of staphylococci to cause systemic infection and to circumvent antibacterial chemotherapy.

  6. Morphological Differentiation of Colon Carcinoma Cell Lines in Rotating Wall Vessels

    NASA Technical Reports Server (NTRS)

    Jessup, J. M.

    1994-01-01

    The objectives of this project were to determine whether (1) microgravity permits unique, three-dimensional cultures of neoplastic human colon tissues and (2) this culture interaction produces novel intestinal growth and differentiation factors. The initial phase of this project tested the efficacy of simulated microgravity for the cultivation and differentiation of human colon carcinoma in rotating wall vessels (RWV's) on microcarrier beads. The RWV's simulate microgravity by randomizing the gravity vector in an aqueous medium under a low shear stress environment in unit gravity. This simulation achieves approximately a one-fifth g environment that allows cells to 'float' and form three-dimensional relationships with less shear stress than in other stirred aqueous medium bioreactors. In the second phase of this project we assessed the ability of human colon carcinoma lines to adhere to various substrates because adhesion is the first event that must occur to create three-dimensional masses. Finally, we tested growth factor production in the last phase of this project.

  7. TRAF1 Deficiency Attenuates Atherosclerosis in Mice by Impairing Monocyte Recruitment to the Vessel Wall

    PubMed Central

    Missiou, Anna; Köstlin, Natascha; Varo, Nerea; Rudolf, Philipp; Aichele, Peter; Ernst, Sandra; Münkel, Christian; Walter, Carina; Stachon, Peter; Sommer, Benjamin; Pfeifer, Dietmar; Zirlik, Katja; MacFarlane, Lindsey; Wolf, Dennis; Tsitsikov, Erdyni; Bode, Christoph; Libby, Peter; Zirlik, Andreas

    2010-01-01

    Background Members of the tumor necrosis factor (TNF) superfamily, such as TNFα, potently promote atherogenesis in mice and humans. TNF receptor-associated factors (TRAFs) are cytoplasmic adaptor proteins for this group of cytokines. Methods and Results This study tested the hypothesis that TRAF1 modulates atherogenesis in vivo. TRAF1−/−/LDLR−/− mice consuming a high-cholesterol diet for 18 weeks developed significantly smaller atherosclerotic lesions compared with LDLR−/− (low density lipoprotein receptor) control animals. As the most prominent change in histologic composition, plaques of TRAF1-deficient animals contained significantly fewer macrophages. Bone marrow transplantations revealed that TRAF1 deficiency on both hematopoetic as well as vascular resident cells contributed to the reduction in atherogenesis observed. Mechanistic studies showed that deficiency of TRAF1 in endothelial cells and monocytes reduced adhesion of inflammatory cells to the endothelium in static and dynamic assays. Impaired adhesion coincided with reduced cell spreading, actin polymerization, and CD29 expression in macrophages, as well as decreased expression of the adhesion molecules ICAM-1 and VCAM-1 on endothelial cells. SiRNA studies on human cells verified these findings. Furthermore, TRAF1 mRNA levels were significantly elevated in blood of patients with acute coronary syndrome. Conclusions TRAF1 deficiency attenuates atherogenesis in mice, most likely due to impaired monocyte recruitment to the vessel wall. These data identify TRAF1 as a potential treatment target for atherosclerosis. PMID:20421522

  8. Extraction of heart and vessel walls on ultrasound images using snake splines

    NASA Astrophysics Data System (ADS)

    Taine, Marie-Claire; Herment, Alain

    1995-05-01

    A segmentation algorithm devoted to extracting heart and vessel walls on ultrasound image sequences was developed. This algorithm is based on a variety of active contours called Snake-Splines. It addresses the specific problems of ultrasonography (texture, dropouts) while using all the information available from temporal redundancy in a scheme of sequence processing for motion analysis. Active contours are 2D deformable models defined as energy- minimizing curves, including internal and external energy terms. The internal energy refers to smoothness constraints characteristics of the curve (controlled continuity splines), whereas the external one refers to forces computed from the gray-level image. A contour B-spline parametrization which intrinsically provides smoothness properties helps formulate the numerical problem with the only consideration of external forces governing the spline curve deformation. The algorithm is tested either on apical and parasternal transthoracic views, or transoesophageal or again intravascular ones, directly digitized at the video output or after recording on video-tapes. However, the methodology can be applied to all structures. The results show the necessity to deal with adaptive iterative process as well as problems associated with numerical stability, and the methodology is currently being extended to tracking structures through image sequences.

  9. Mapping strain exerted on blood vessel walls using deuterium double-quantum-filtered MRI

    PubMed Central

    Sharf, Yehuda; Seo, Yoshiteru; Eliav, Uzi; Akselrod, Solang; Navon, Gil

    1998-01-01

    A technique is described for displaying distinct tissue layers of large blood vessel walls as well as measuring their mechanical strain. The technique is based on deuterium double-quantum-filtered (DQF) spectroscopic imaging. The effectiveness of the double-quantum filtration in suppressing the signal of bulk water is demonstrated on a phantom consisting of rat tail tendon fibers. Only intrafibrillar water is displayed, excluding all other signals of water molecules that reorient isotropically. One- and two-dimensional spectroscopic imaging of bovine aorta and coronary arteries show the characteristic DQF spectrum of each of the tissue layers. This property is used to obtain separate images of the outer layer, the tunica adventitia, or the intermediate layer, the tunica media, or both. To visualize the effect of elongation, the average residual quadrupole splitting <Δνq> is calculated for each pixel. Two-dimensional deuterium quadrupolar splitting images are obtained for a fully relaxed and a 55% elongated sample of bovine coronary artery. These images indicate that the strong effect of strain is associated with water molecules in the tunica adventitia whereas the DQF NMR signal of water in the tunica media is apparently strain-insensitive. After appropriate calibration, these average quadrupolar splitting images can be interpreted as strain maps. PMID:9539698

  10. Mapping strain exerted on blood vessel walls using deuterium double-quantum-filtered MRI.

    PubMed

    Sharf, Y; Seo, Y; Eliav, U; Akselrod, S; Navon, G

    1998-04-14

    A technique is described for displaying distinct tissue layers of large blood vessel walls as well as measuring their mechanical strain. The technique is based on deuterium double-quantum-filtered (DQF) spectroscopic imaging. The effectiveness of the double-quantum filtration in suppressing the signal of bulk water is demonstrated on a phantom consisting of rat tail tendon fibers. Only intrafibrillar water is displayed, excluding all other signals of water molecules that reorient isotropically. One- and two-dimensional spectroscopic imaging of bovine aorta and coronary arteries show the characteristic DQF spectrum of each of the tissue layers. This property is used to obtain separate images of the outer layer, the tunica adventitia, or the intermediate layer, the tunica media, or both. To visualize the effect of elongation, the average residual quadrupole splitting is calculated for each pixel. Two-dimensional deuterium quadrupolar splitting images are obtained for a fully relaxed and a 55% elongated sample of bovine coronary artery. These images indicate that the strong effect of strain is associated with water molecules in the tunica adventitia whereas the DQF NMR signal of water in the tunica media is apparently strain-insensitive. After appropriate calibration, these average quadrupolar splitting images can be interpreted as strain maps.

  11. A synthetic model for blood coagulation including blood slip at the vessel wall.

    PubMed

    Fasano, Antonio; Pavlova, Jevgenija; Sequeira, Adélia

    2013-01-01

    Modeling blood coagulation has taken various directions in recent years, depending on the aspects that authors wish to emphasize. In this paper we want to address an issue that has been systematically ignored in the relevant literature, namely the effect of blood slip at the vessels wall. The presence of a slip results in an increased supply of activated platelets to the clotting site. We calculate such a contribution showing that, in extreme cases, it can be even dominant. Indeed, raising the concentration of activated platelets induces an acceleration of thrombin production and eventually of the whole clot progression. The model explains the difference between arterial and venous thrombi. We confine to the coagulation stage known as "propagation phase" in the context of the so called cell based model. The paper is preparatory for a deeper analysis in which the clotting process is coupled to blood rheology and that will be carried out in the future by the same authors. At the present stage, the extremely complex biochemistry has been simplified adopting a leaner, though virtual, system of diffusion-convection-reaction equations, in the optics of providing "modular" models, that can be reduced or enlarged so to meet specific modeling requirements.

  12. Nitric oxide affects preimplantation embryonic development in a rotating wall vessel bioreactor simulating microgravity.

    PubMed

    Cao, Yu-jing; Fan, Xun-jun; Shen, Zheng; Ma, Bao-hua; Duan, En-kui

    2007-01-01

    Microgravity was simulated with a rotating wall vessel bioreactor (RWVB) in order to study its effect on pre-implantation embryonic development in mice. Three experimental groups were used: stationary control, rotational control and clinostat rotation. Three experiments were performed as follows. The first experiment showed that compared with the other two (control) groups, embryonic development was significantly retarded after 72 h in the clinostat rotation group. The second experiment showed that more nitric oxide (NO) was produced in the culture medium in the clinostat rotation group after 72 h (P<0.05), and the nitric oxide synthase (NOS) activity in this group was significantly higher than in the controls (P<0.01). In the third experiment, we studied apoptosis in the pre-implantation mouse embryos after 72 h in culture and found that Annexin-V staining was negative in the normal (stationary and rotational control) embryos, but the developmentally retarded (clinostat rotation) embryos showed a strong green fluorescence. These results indicate that microgravity induced developmental retardation and cell apoptosis in the mouse embryos. We presume that these effects are related to the higher concentration of NO in the embryos under microgravity, which have cause cytotoxic consequences.

  13. Improved black-blood imaging using DANTE-SPACE for simultaneous carotid and intracranial vessel wall evaluation.

    PubMed

    Xie, Yibin; Yang, Qi; Xie, Guoxi; Pang, Jianing; Fan, Zhaoyang; Li, Debiao

    2016-06-01

    The purpose of this study was to develop a three-dimensional black blood imaging method for simultaneously evaluating the carotid and intracranial arterial vessel walls with high spatial resolution and excellent blood suppression with and without contrast enhancement. The delay alternating with nutation for tailored excitation (DANTE) preparation module was incorporated into three-dimensional variable flip angle turbo spin echo (SPACE) sequence to improve blood signal suppression. Simulations and phantom studies were performed to quantify image contrast variations induced by DANTE. DANTE-SPACE, SPACE, and two-dimensional turbo spin echo were compared for apparent signal-to-noise ratio, contrast-to-noise ratio, and morphometric measurements in 14 healthy subjects. Preliminary clinical validation was performed in six symptomatic patients. Apparent residual luminal blood was observed in five (pre-contrast) and nine (post-contrast) subjects with SPACE and only two (post-contrast) subjects with DANTE-SPACE. DANTE-SPACE showed 31% (pre-contrast) and 100% (post-contrast) improvement in wall-to-blood contrast-to-noise ratio over SPACE. Vessel wall area measured from SPACE was significantly larger than that from DANTE-SPACE due to possible residual blood signal contamination. DANTE-SPACE showed the potential to detect vessel wall dissection and identify plaque components in patients. DANTE-SPACE significantly improved arterial and venous blood suppression compared with SPACE. Simultaneous high-resolution carotid and intracranial vessel wall imaging to potentially identify plaque components was feasible with a scan time under 6 min. Magn Reson Med 75:2286-2294, 2016. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

  14. Cell culture for three-dimensional modeling in rotating-wall vessels: an application of simulated microgravity

    NASA Technical Reports Server (NTRS)

    Schwarz, R. P.; Goodwin, T. J.; Wolf, D. A.

    1992-01-01

    High-density, three-dimensional cell cultures are difficult to grow in vitro. The rotating-wall vessel (RWV) described here has cultured BHK-21 cells to a density of 1.1 X 10(7) cells/ml. Cells on microcarriers were observed to grow with enhanced bridging in this batch culture system. The RWV is a horizontally rotated tissue culture vessel with silicon membrane oxygenation. This design results in a low-turbulence, low-shear cell culture environment with abundant oxygenation. The RWV has the potential to culture a wide variety of normal and neoplastic cells.

  15. Numerical Simulation of Impact Damage Induced by Orbital Debris on Shielded Wall of Composite Overwrapped Pressure Vessel

    NASA Astrophysics Data System (ADS)

    Cherniaev, Aleksandr; Telichev, Igor

    2014-12-01

    This paper presents a methodology for numerical simulation of the formation of the front wall damage in composite overwrapped pressure vessels under hypervelocity impact. Both SPH particles and Lagrangian finite elements were employed in combination for numerical simulations. Detailed numerical models implementing two filament winding patterns with different degree of interweaving were developed and used to simulate 2.5 km/s and 5.0 km/s impacts of 5 mm-diameter spherical aluminum-alloy projectile. Obtained results indicate that winding pattern may have a pronounced effect on vessel damage in case of orbital debris impact, influencing propagation of the stress waves in composite material.

  16. Cell culture for three-dimensional modeling in rotating-wall vessels: an application of simulated microgravity

    NASA Technical Reports Server (NTRS)

    Schwarz, R. P.; Goodwin, T. J.; Wolf, D. A.

    1992-01-01

    High-density, three-dimensional cell cultures are difficult to grow in vitro. The rotating-wall vessel (RWV) described here has cultured BHK-21 cells to a density of 1.1 X 10(7) cells/ml. Cells on microcarriers were observed to grow with enhanced bridging in this batch culture system. The RWV is a horizontally rotated tissue culture vessel with silicon membrane oxygenation. This design results in a low-turbulence, low-shear cell culture environment with abundant oxygenation. The RWV has the potential to culture a wide variety of normal and neoplastic cells.

  17. Identifying New Components Participating in the Secondary Cell Wall Formation of Vessel Elements in Zinnia and Arabidopsis[W

    PubMed Central

    Endo, Satoshi; Pesquet, Edouard; Yamaguchi, Masatoshi; Tashiro, Gen; Sato, Mayuko; Toyooka, Kiminori; Nishikubo, Nobuyuki; Udagawa-Motose, Makiko; Kubo, Minoru; Fukuda, Hiroo; Demura, Taku

    2009-01-01

    Xylem vessel elements are hollow cellular units that assemble end-to-end to form a continuous vessel throughout the plant body; the xylem vessel is strengthened by the xylem elements' reinforced secondary cell walls (SCWs). This work aims to unravel the contribution of unknown actors in xylem vessel differentiation using the model in vitro cell culture system of Zinnia elegans differentiating cell cultures and the model in vivo system of Arabidopsis thaliana plants. Tracheary Element Differentiation-Related6 (TED6) and TED7 were selected based on an RNA interference (RNAi) screen in the Zinnia system. RNAi reduction of TED6 and 7 delayed tracheary element (TE) differentiation and co-overexpression of TED6 and 7 increased TE differentiation in cultured Zinnia cells. Arabidopsis TED6 and 7 were expressed preferentially in differentiating vessel elements in seedlings. Aberrant SCW formation of root vessel elements was induced by transient RNAi of At TED7 alone and enhanced by inhibition of both TED6 and 7. Protein–protein interactions were demonstrated between TED6 and a subunit of the SCW-related cellulose synthase complex. Our strategy has succeeded in finding two novel components in SCW formation and has opened the door for in-depth analysis of their molecular functions. PMID:19383897

  18. Identifying new components participating in the secondary cell wall formation of vessel elements in zinnia and Arabidopsis.

    PubMed

    Endo, Satoshi; Pesquet, Edouard; Yamaguchi, Masatoshi; Tashiro, Gen; Sato, Mayuko; Toyooka, Kiminori; Nishikubo, Nobuyuki; Udagawa-Motose, Makiko; Kubo, Minoru; Fukuda, Hiroo; Demura, Taku

    2009-04-01

    Xylem vessel elements are hollow cellular units that assemble end-to-end to form a continuous vessel throughout the plant body; the xylem vessel is strengthened by the xylem elements' reinforced secondary cell walls (SCWs). This work aims to unravel the contribution of unknown actors in xylem vessel differentiation using the model in vitro cell culture system of Zinnia elegans differentiating cell cultures and the model in vivo system of Arabidopsis thaliana plants. Tracheary Element Differentiation-Related6 (TED6) and TED7 were selected based on an RNA interference (RNAi) screen in the Zinnia system. RNAi reduction of TED6 and 7 delayed tracheary element (TE) differentiation and co-overexpression of TED6 and 7 increased TE differentiation in cultured Zinnia cells. Arabidopsis TED6 and 7 were expressed preferentially in differentiating vessel elements in seedlings. Aberrant SCW formation of root vessel elements was induced by transient RNAi of At TED7 alone and enhanced by inhibition of both TED6 and 7. Protein-protein interactions were demonstrated between TED6 and a subunit of the SCW-related cellulose synthase complex. Our strategy has succeeded in finding two novel components in SCW formation and has opened the door for in-depth analysis of their molecular functions.

  19. Semiautomatic vessel wall detection and quantification of wall thickness in computed tomography images of human abdominal aortic aneurysms

    SciTech Connect

    Shum, Judy; DiMartino, Elena S.; Goldhammer, Adam; Goldman, Daniel H.; Acker, Leah C.; Patel, Gopal; Ng, Julie H.; Martufi, Giampaolo; Finol, Ender A.

    2010-02-15

    Purpose: Quantitative measurements of wall thickness in human abdominal aortic aneurysms (AAAs) may lead to more accurate methods for the evaluation of their biomechanical environment. Methods: The authors describe an algorithm for estimating wall thickness in AAAs based on intensity histograms and neural networks involving segmentation of contrast enhanced abdominal computed tomography images. The algorithm was applied to ten ruptured and ten unruptured AAA image data sets. Two vascular surgeons manually segmented the lumen, inner wall, and outer wall of each data set and a reference standard was defined as the average of their segmentations. Reproducibility was determined by comparing the reference standard to lumen contours generated automatically by the algorithm and a commercially available software package. Repeatability was assessed by comparing the lumen, outer wall, and inner wall contours, as well as wall thickness, made by the two surgeons using the algorithm. Results: There was high correspondence between automatic and manual measurements for the lumen area (r=0.978 and r=0.996 for ruptured and unruptured aneurysms, respectively) and between vascular surgeons (r=0.987 and r=0.992 for ruptured and unruptured aneurysms, respectively). The authors' automatic algorithm showed better results when compared to the reference with an average lumen error of 3.69%, which is less than half the error between the commercially available application Simpleware and the reference (7.53%). Wall thickness measurements also showed good agreement between vascular surgeons with average coefficients of variation of 10.59% (ruptured aneurysms) and 13.02% (unruptured aneurysms). Ruptured aneurysms exhibit significantly thicker walls (1.78{+-}0.39 mm) than unruptured ones (1.48{+-}0.22 mm), p=0.044. Conclusions: While further refinement is needed to fully automate the outer wall segmentation algorithm, these preliminary results demonstrate the method's adequate reproducibility

  20. Three-dimensional T2-weighted MRI of the Human Femoral Arterial Vessel Wall at 3.0Tesla

    PubMed Central

    Zhang, Zhuoli; Fan, Zhaoyang; Carroll, Timothy J.; Chung, YiuCho; Weale, Peter; Jerecic, Renate; Li, Debiao

    2010-01-01

    OBJECTIVES To evaluate the potential use of a novel 3D turbo spin-echo (TSE) T2-weighted (T2w) technique for assessing the vessel wall in the superficial femoral artery at 3.0T. BACKGROUND Magnetic resonance imaging (MRI) can be used for the noninvasive assessment of atherosclerotic plaque burden in the peripheral circulation. While black-blood 2D TSE techniques have been used for femoral arterial wall imaging, these techniques require prolonged imaging time to cover a large field of view required to cover the leg. Recently, variable-flip-angle 3D TSE T2w (SPACE) has been introduced as a fast vessel wall imaging technique with submillimeter spatial resolution. A systematic investigation of the application of this technique to femoral arterial wall imaging has yet to be performed. METHODS Fifteen healthy volunteers and 3 patients with peripheral arterial disease (PAD) underwent 3D SPACE imaging of the superficial femoral artery at 3.0T, with the conventional 2D TSE T2w imaging as a reference. Muscle-lumen contrast to noise ratio (CNR) and wall/lumen volumes (WV, LV) were measured at the matched locations on the 3D and 2D image sets. Statistical comparison on a per-subject basis was conducted to determine the difference and agreement between 3D SPACE and the 2D TSE techniques. RESULTS The 3D SPACE data sets enabled vessel visualization from arbitrary orientation through multi-planar reformation (MPR) technique. Muscle-lumen CNR was significantly higher with 3D SPACE than with the 2D TSE (3.12 ± 0.84 vs. 2.17 ± 0.34, p < 0.01). This trend was confirmed when CNR efficiency (CNReff) values were further compared. A similar trend was observed in PAD patients (SPACE vs. 2D TSE T2w: CNR 2.35 ± 0.13 vs. 1.77 ± 0.25; CNReff 15.35 ± 0.61 vs. 3.59 ± 2.62. all p < 0.05). Measurements of WV and LV from the 3D and 2D techniques were highly correlated in volunteers and PAD patients (volunteers, WV: linear regression r2 = 0.98, LV: r2 = 0.98, p < 0.001 for both; patients, WV

  1. Lymphocyte trafficking and HIV infection of human lymphoid tissue in a rotating wall vessel bioreactor

    NASA Technical Reports Server (NTRS)

    Margolis, L. B.; Fitzgerald, W.; Glushakova, S.; Hatfill, S.; Amichay, N.; Baibakov, B.; Zimmerberg, J.

    1997-01-01

    The pathogenesis of HIV infection involves a complex interplay between both the infected and noninfected cells of human lymphoid tissue, the release of free viral particles, the de novo infection of cells, and the recirculatory trafficking of peripheral blood lymphocytes. To develop an in vitro model for studying these various aspects of HIV pathogenesis we have utilized blocks of surgically excised human tonsils and a rotating wall vessel (RWV) cell culture system. Here we show that (1) fragments of the surgically excised human lymphoid tissue remain viable and retain their gross cytoarchitecture for at least 3 weeks when cultured in the RWV system; (2) such lymphoid tissue gradually shows a loss of both T and B cells to the surrounding growth medium; however, this cellular migration is reversible as demonstrated by repopulation of the tissue by labeled cells from the growth medium; (3) this cellular migration may be partially or completely inhibited by embedding the blocks of lymphoid tissue in either a collagen or agarose gel matrix; these embedded tissue blocks retain most of the basic elements of a normal lymphoid cytoarchitecture; and (4) both embedded and nonembedded RWV-cultured blocks of human lymphoid tissue are capable of productive infection by HIV-1 of at least three various strains of different tropism and phenotype, as shown by an increase in both p24 antigen levels and free virus in the culture medium, and by the demonstration of HIV-1 RNA-positive cells inside the tissue identified by in situ hybridization. It is therefore reasonable to suggest that gel-embedded and nonembedded blocks of human lymphoid tissue, cocultured with a suspension of tonsillar lymphocytes in an RWV culture system, constitute a useful model for simulating normal lymphocyte recirculatory traffic and provide a new tool for testing the various aspects of HIV pathogenesis.

  2. Lytic and mechanical stability of clots composed of fibrin and blood vessel wall components.

    PubMed

    Rottenberger, Z; Komorowicz, E; Szabó, L; Bóta, A; Varga, Z; Machovich, R; Longstaff, C; Kolev, K

    2013-03-01

    Proteases expressed in atherosclerotic plaque lesions generate collagen fragments, release glycosaminoglycans (chondroitin sulfate [CS] and dermatan sulfate [DS]) and expose extracellular matrix (ECM) proteins (e.g. decorin) at sites of fibrin formation. Here we address the effect of these vessel wall components on the lysis of fibrin by the tissue plasminogen activator (tPA)/plasminogen system and on the mechanical stability of clots. MMP-8-digested collagen fragments, isolated CS, DS, glycosylated decorin and its core protein were used to prepare mixed matrices with fibrin (additives present at a 50-fold lower mass concentration than fibrinogen). Scanning electron microscopy (SEM) showed that the presence of ECM components resulted in a coarse fibrin structure, most pronounced for glycosylated decorin causing an increase in the median fiber diameter from 85 to 187 nm. Rheological measurements indicated that these structural alterations were coupled to decreased shear resistance (1.8-fold lower shear stress needed for gel/fluid transition of the clots containing glycosylated decorin) and rigidity (reduction of the storage modulus from 54.3 to 33.2 Pa). The lytic susceptibility of the modified fibrin structures was increased. The time to 50% lysis by plasmin was reduced approximately 2-fold for all investigated ECM components (apart from the core protein of decorin which produced a moderate reduction of the lysis time by 25%), whereas fibrin-dependent plasminogen activation by tPA was inhibited by up to 30%. ECM components compromise the chemical and mechanical stability of fibrin as a result of changes in its ultrastructure. © 2012 International Society on Thrombosis and Haemostasis.

  3. Lymphocyte trafficking and HIV infection of human lymphoid tissue in a rotating wall vessel bioreactor

    NASA Technical Reports Server (NTRS)

    Margolis, L. B.; Fitzgerald, W.; Glushakova, S.; Hatfill, S.; Amichay, N.; Baibakov, B.; Zimmerberg, J.

    1997-01-01

    The pathogenesis of HIV infection involves a complex interplay between both the infected and noninfected cells of human lymphoid tissue, the release of free viral particles, the de novo infection of cells, and the recirculatory trafficking of peripheral blood lymphocytes. To develop an in vitro model for studying these various aspects of HIV pathogenesis we have utilized blocks of surgically excised human tonsils and a rotating wall vessel (RWV) cell culture system. Here we show that (1) fragments of the surgically excised human lymphoid tissue remain viable and retain their gross cytoarchitecture for at least 3 weeks when cultured in the RWV system; (2) such lymphoid tissue gradually shows a loss of both T and B cells to the surrounding growth medium; however, this cellular migration is reversible as demonstrated by repopulation of the tissue by labeled cells from the growth medium; (3) this cellular migration may be partially or completely inhibited by embedding the blocks of lymphoid tissue in either a collagen or agarose gel matrix; these embedded tissue blocks retain most of the basic elements of a normal lymphoid cytoarchitecture; and (4) both embedded and nonembedded RWV-cultured blocks of human lymphoid tissue are capable of productive infection by HIV-1 of at least three various strains of different tropism and phenotype, as shown by an increase in both p24 antigen levels and free virus in the culture medium, and by the demonstration of HIV-1 RNA-positive cells inside the tissue identified by in situ hybridization. It is therefore reasonable to suggest that gel-embedded and nonembedded blocks of human lymphoid tissue, cocultured with a suspension of tonsillar lymphocytes in an RWV culture system, constitute a useful model for simulating normal lymphocyte recirculatory traffic and provide a new tool for testing the various aspects of HIV pathogenesis.

  4. Nafazatrom (BAY g 6575), a potent stimulator of prostacyclin release from cardiac and renal vessel wall.

    PubMed

    Klitzke, A K

    1984-10-01

    The enhancement of prostacyclin (PGI2) formation in the cardiac and renal vessel wall by nafazatrom (BAY g 6575) and the vascular effects of this drug were studied in a series of experiments on perfused isolated rat hearts and kidneys. A dose-dependent increase of prostacyclin release (measured as 6-Keto-PGF1 alpha levels, delta % of control) from the vascular endothelium was achieved when nafazatrom was applied in concentrations ranging from 5 X 10(-7) to 10(-5) g/ml. In the heart, the minimal effective dose of nafazatrom was 5 X 10(-7) g/ml causing a 23 delta % increase of PGI2 release; maximal stimulation of PGI2 was 276 delta % at 5 X 10(-6) g/ml nafazatrom. In the kidney, only at the highest concentration of 10(-5) g/ml an increase of PGI2 to 192 delta % was found. Concomitant to the PGI2 release, in both organs, a reduction of perfusion pressure (delta % of control) was observed. Minimal vasodilation in the heart was - 9.6 delta % (5 X 10(-6) g/ml nafazatrom); the maximal effect was - 25.7 delta % (5 X 10(-6) g/ml nafazatrom). In the kidney, the only observed reduction of perfusion pressure was - 12 delta % at 10(-5) g/ml nafazatrom. The cyclooxygenase inhibitor indomethacin (10(-5) g/ml) blocked vasodilation produced by nafazatrom (5 X 10(-6) g/ml); delta P % was 0.5 + 1.

  5. Computerized flow and vessel wall analyses of coronary arteries for detection of non-calcified plaques in coronary CT angiography

    NASA Astrophysics Data System (ADS)

    Wei, Jun; Zhou, Chuan; Chan, Heang-Ping; Chughtai, Aamer; Agarwal, Prachi; Hadjiiski, Lubomir; Kazerooni, Ella

    2016-03-01

    The buildup of non-calcified plaques (NCP) that are vulnerable to rupture in coronary arteries is a risk for myocardial infarction. We are developing a computer-aided detection (CADe) system to assist radiologists in detecting NCPs in cCTA. A major challenge of NCP detection is the large number of false positives (FPs) caused by the small sized coronary arteries, image noise and artifacts. In this study, our purpose is to design new image features to reduce FPs. A data set of 98 cCTA scans was retrospectively collected from patient files. We first used vessel wall analysis, in which topological features were extracted from vessel wall and fused with a support-vector machine, to identify the NCP candidates from the segmented coronary tree. Computerized flow dynamic (CFD) features that characterize the change in blood flow due to the presence of plaques and a vascular cross-sectional (VCS) feature that quantifies the presence of low attenuation region at the vessel wall were designed for FP reduction. Using a leave-one-out resampling method, a support vector machine classifier was trained to merge the features into a NCP likelihood score using the vessel wall features alone or in combination with the new CDF and VCS features. The performance of the new features in classification of true NCPs and FPs was evaluated by the area under the receiver operating characteristic (ROC) curve (AUC). Without the new CFD and VCS features, the test AUC was 0.84+/-0.01. The AUC was improved to 0.88+/-0.01 with the addition of the new features. The improvement was statistically significant (p < 0.001). The study indicated that the new flow dynamic and vascular cross-sectional features were useful for differentiation of NCPs from FPs in cCTA.

  6. Qualitative Evaluation of a High-Resolution 3D Multi-Sequence Intracranial Vessel Wall Protocol at 3 Tesla MRI.

    PubMed

    Dieleman, Nikki; Yang, Wenjie; van der Kolk, Anja G; Abrigo, Jill; Lee, Ka Lok; Chu, Winnie Chiu Wing; Zwanenburg, Jaco J M; Siero, Jeroen C W; Wong, Ka Sing; Hendrikse, Jeroen; Chen, Fiona Xiang Yan

    2016-01-01

    Intracranial vessel wall imaging using MRI has great potential as a clinical method for assessing intracranial atherosclerosis. The purpose of the current study was to compare three 3T MRI vessel wall sequences with different contrast weightings (T1w, PD, T2w) and dedicated sagittal orientation perpendicular to the middle cerebral artery, to the reconstructed sagittal image from a transverse 3D T1w volumetric isotropically reconstructed turbo spin-echo acquisition (VIRTA), and provide a clinical recommendation. The above-mentioned sequences were acquired in 10 consecutive Chinese ischemic stroke or TIA patients (age: 68 years, sex: 4 females) with angiographic-confirmed MCA stenosis at 3T. Institutional review board approval was obtained. Two raters qualitatively scored all images on overall image quality, presence of artifacts, and visibility of plaques. Data were compared using Repeated measures ANOVA and Sidak's adjusted post hoc tests. All sequences except the T2w sequence were able to depict the walls of the large vessels of the Circle of Willis (p<0.05). T1w sagittal oblique VIRTA showed significantly more artifacts (p<0.01). Peripherally located plaques were sometimes missed on the sagittal sequences, but could be appreciated on the transverse T1w VIRTA. With the 3T multi-sequence vessel wall protocol we were able to assess the intracranial plaque with two different image contrast weightings. The sequence of preference to include in a clinical protocol would be the transverse 3D T1w VIRTA based on absence of artifacts, larger coverage including the whole Circle of Willis, and excellent lesion depiction.

  7. Suitability of pharmacokinetic models for dynamic contrast-enhanced MRI of abdominal aortic aneurysm vessel wall: a comparison.

    PubMed

    Nguyen, V Lai; Kooi, M Eline; Backes, Walter H; van Hoof, Raf H M; Saris, Anne E C M; Wishaupt, Mirthe C J; Hellenthal, Femke A M V I; van der Geest, Rob J; Kessels, Alfons G H; Schurink, Geert Willem H; Leiner, Tim

    2013-01-01

    Increased microvascularization of the abdominal aortic aneurysm (AAA) vessel wall has been related to AAA progression and rupture. The aim of this study was to compare the suitability of three pharmacokinetic models to describe AAA vessel wall enhancement using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). Patients with AAA underwent DCE-MRI at 1.5 Tesla. The volume transfer constant (K(trans) ), which reflects microvascular flow, permeability and surface area, was calculated by fitting the blood and aneurysm vessel wall gadolinium concentration curves. The relative fit errors, parameter uncertainties and parameter reproducibilities for the Patlak, Tofts and Extended Tofts model were compared to find the most suitable model. Scan-rescan reproducibility was assessed using the interclass correlation coefficient and coefficient of variation (CV). Further, the relationship between K(trans) and AAA size was investigated. DCE-MRI examinations from thirty-nine patients (mean age±SD: 72±6 years; M/F: 35/4) with an mean AAA maximal diameter of 49±6 mm could be included for pharmacokinetic analysis. Relative fit uncertainties for K(trans) based on the Patlak model (17%) were significantly lower compared to the Tofts (37%) and Extended Tofts model (42%) (p<0.001). K(trans) scan-rescan reproducibility for the Patlak model (ICC = 0.61 and CV = 22%) was comparable with the Tofts (ICC = 0.61, CV = 23%) and Extended Tofts model (ICC = 0.76, CV = 22%). K(trans) was positively correlated with maximal AAA diameter (Spearman's ρ = 0.38, p = 0.02) using the Patlak model. Using the presented imaging protocol, the Patlak model is most suited to describe DCE-MRI data of the AAA vessel wall with good K(trans) scan-rescan reproducibility.

  8. An In Vitro Model for the Study of Platelet-Vessel Wall Interactions Following a Freeze-Thaw Injury,

    DTIC Science & Technology

    1983-03-16

    thaw insult. Using this model, control ;aortas (370C) perfused with platelet rich plasma ( PRP ) or gel filtered platelets D ; Un 147 Mn oOF I NOV GIS...vessel wall interactions following freeze-thaw insult. Using this model, control aortas (37°C) perfused with platelet rich plasma ( PRP ) or gel filtered...collected from unanestized calves via the jugular vein into plastic centrifuge bottles, containing 25 ml of anticoagulant (acid citrate dextrose, NIH

  9. PEG-albumin supraplasma expansion is due to increased vessel wall shear stress induced by blood viscosity shear thinning.

    PubMed

    Sriram, Krishna; Tsai, Amy G; Cabrales, Pedro; Meng, Fantao; Acharya, Seetharama A; Tartakovsky, Daniel M; Intaglietta, Marcos

    2012-06-15

    We studied the extreme hemodilution to a hematocrit of 11% induced by three plasma expanders: polyethylene glycol (PEG)-conjugated albumin (PEG-Alb), 6% 70-kDa dextran, and 6% 500-kDa dextran. The experimental component of our study relied on microelectrodes and cardiac output to measure both the rheological properties of plasma-expander blood mixtures and nitric oxide (NO) bioavailability in vessel walls. The modeling component consisted of an analysis of the distribution of wall shear stress (WSS) in the microvessels. Our experiments demonstrated that plasma expansion with PEG-Alb caused a state of supraperfusion with cardiac output 40% above baseline, significantly increased NO vessel wall bioavailability, and lowered peripheral vascular resistance. We attributed this behavior to the shear thinning nature of blood and PEG-Alb mixtures. To substantiate this hypothesis, we developed a mathematical model of non-Newtonian blood flow in a vessel. Our model used the Quemada rheological constitutive relationship to express blood viscosity in terms of both hematocrit and shear rate. The model revealed that the net effect of the hemodilution induced by relatively low-viscosity shear thinning PEG-Alb plasma expanders is to reduce overall blood viscosity and to increase the WSS, thus intensifying endothelial NO production. These changes act synergistically, significantly increasing cardiac output and perfusion due to lowered overall peripheral vascular resistance.

  10. Radiation Protection Using Single-Wall Carbon Nanotube Derivatives

    NASA Technical Reports Server (NTRS)

    Tour, James M.; Lu, Meng; Lucente-Schultz, Rebecca; Leonard, Ashley; Doyle, Condell Dewayne; Kosynkin, Dimitry V.; Price, Brandi Katherine

    2011-01-01

    This invention is a means of radiation protection, or cellular oxidative stress mitigation, via a sequence of quenching radical species using nano-engineered scaffolds, specifically single-wall carbon nanotubes (SWNTs) and their derivatives. The material can be used as a means of radiation protection by reducing the number of free radicals within, or nearby, organelles, cells, tissue, organs, or living organisms, thereby reducing the risk of damage to DNA and other cellular components (i.e., RNA, mitochondria, membranes, etc.) that can lead to chronic and/or acute pathologies, including but not limited to cancer, cardiovascular disease, immuno-suppression, and disorders of the central nervous system. In addition, this innovation could be used as a prophylactic or antidote for accidental radiation exposure, during high-altitude or space travel where exposure to radiation is anticipated, or to protect from exposure from deliberate terrorist or wartime use of radiation- containing weapons.

  11. Imaging of wall motion coupled with blood flow velocity in the heart and vessels in vivo: a feasibility study.

    PubMed

    Luo, Jianwen; Konofagou, Elisa E

    2011-06-01

    The mechanical property and geometry changes as a result of cardiovascular disease affect both the wall motion and blood flow in the heart and vessels, whereas the latter two are also coupled and therefore continuously influence one another. Simultaneous and registered imaging of both cardiovascular wall motion and blood velocity may thus contribute to more complete computational models of cardiovascular mechanical and fluid dynamics as well as provide additional diagnostic information. The objective of this paper was to determine the feasibility of imaging cardiovascular wall motion coupled with blood flow in vivo. Normal (n = 6) and infarcted (n = 5) murine left ventricles, and normal (n = 5) and aneurysmal (n = 4) murine abdominal aortas, were imaged in longitudinal views with a 30-MHz ultrasound probe. Using electrocardiogram (ECG) gating, 2-D radio-frequency (RF) data were acquired at a frame rate of 8 kHz. The axial wall velocity and blood velocity were estimated using a speckle-tracking technique. Spatially and temporally registered imaging of both cardiovascular wall motion and blood flow was shown to be feasible. Reduced wall motion was detected in the infarcted region, whereas vortex flow patterns were imaged in diastolic phases of both normal and infarcted left ventricles. The myocardial wall motion and blood flow were found to be more synchronous in the normal heart, where the blood moves toward the anteroseptal wall after the mitral valve opens (i.e., rapid filling phase), and the anteroseptal wall simultaneously undergoes outward motion. In the infarcted heart, however, in the rapid filling phase, the basal anteroseptal wall starts moving about 20 ms before the mitral valve opens and the blood enters the left ventricle. In the normal aorta, the wall motion and blood velocity were uniform and synchronous. In the aneurysmal aorta, reduced and spatially varied wall motion and vortex flow patterns in the aneurysmal sac were found. The wall motion and

  12. Protective interior wall and attaching means for a fusion reactor vacuum vessel

    DOEpatents

    Phelps, R.D.; Upham, G.A.; Anderson, P.M.

    1985-03-01

    The wall basically consists of an array of small rectangular plates attached to the existing walls with threaded fasteners. The protective wall effectively conceals and protects all mounting hardware beneath the plate array, while providing a substantial surface area that will absorb plasma energy.

  13. Vessel Wall Enhancement and Blood-Cerebrospinal Fluid Barrier Disruption After Mechanical Thrombectomy in Acute Ischemic Stroke.

    PubMed

    Renú, Arturo; Laredo, Carlos; Lopez-Rueda, Antonio; Llull, Laura; Tudela, Raúl; San-Roman, Luis; Urra, Xabier; Blasco, Jordi; Macho, Juan; Oleaga, Laura; Chamorro, Angel; Amaro, Sergio

    2017-03-01

    Less than half of acute ischemic stroke patients treated with mechanical thrombectomy obtain permanent clinical benefits. Consequently, there is an urgent need to identify mechanisms implicated in the limited efficacy of early reperfusion. We evaluated the predictors and prognostic significance of vessel wall permeability impairment and its association with blood-cerebrospinal fluid barrier (BCSFB) disruption after acute stroke treated with thrombectomy. A prospective cohort of acute stroke patients treated with stent retrievers was analyzed. Vessel wall permeability impairment was identified as gadolinium vessel wall enhancement (GVE) in a 24- to 48-hour follow-up contrast-enhanced magnetic resonance imaging, and severe BCSFB disruption was defined as subarachnoid hemorrhage or gadolinium sulcal enhancement (present across >10 slices). Infarct volume was evaluated in follow-up magnetic resonance imaging, and clinical outcome was evaluated with the modified Rankin Scale at day 90. A total of 60 patients (median National Institutes of Health Stroke Scale score, 18) were analyzed, of whom 28 (47%) received intravenous alteplase before mechanical thrombectomy. Overall, 34 (57%) patients had GVE and 27 (45%) had severe BCSFB disruption. GVE was significantly associated with alteplase use before thrombectomy and with more stent retriever passes, along with the presence of severe BCSFB disruption. GVE was associated with poor clinical outcome, and both GVE and severe BCSFB disruption were associated with increased final infarct volume. These findings may support the clinical relevance of direct vessel damage and BCSFB disruption after acute stroke and reinforce the need for further improvements in reperfusion strategies. Further validation in larger cohorts of patients is warranted. © 2017 American Heart Association, Inc.

  14. Effects of simulated weightlessness on fish otolith growth: Clinostat versus Rotating-Wall Vessel

    NASA Astrophysics Data System (ADS)

    Brungs, Sonja; Hauslage, Jens; Hilbig, Reinhard; Hemmersbach, Ruth; Anken, Ralf

    2011-09-01

    Stimulus dependence is a general feature of developing sensory systems. It has been shown earlier that the growth of inner ear heavy stones (otoliths) of late-stage Cichlid fish ( Oreochromis mossambicus) and Zebrafish ( Danio rerio) is slowed down by hypergravity, whereas microgravity during space flight yields an opposite effect, i.e. larger than 1 g otoliths, in Swordtail ( Xiphophorus helleri) and in Cichlid fish late-stage embryos. These and related studies proposed that otolith growth is actively adjusted via a feedback mechanism to produce a test mass of the appropriate physical capacity. Using ground-based techniques to apply simulated weightlessness, long-term clinorotation (CR; exposure on a fast-rotating Clinostat with one axis of rotation) led to larger than 1 g otoliths in late-stage Cichlid fish. Larger than normal otoliths were also found in early-staged Zebrafish embryos after short-term Wall Vessel Rotation (WVR; also regarded as a method to simulate weightlessness). These results are basically in line with the results obtained on Swordtails from space flight. Thus, the growth of fish inner ear otoliths seems to be an appropriate parameter to assess the quality of "simulated weightlessness" provided by a particular simulation device. Since CR and WVR are in worldwide use to simulate weightlessness conditions on ground using small-sized specimens, we were prompted to directly compare the effects of CR and WVR on otolith growth using developing Cichlids as model organism. Animals were simultaneously subjected to CR and WVR from a point of time when otolith primordia had begun to calcify both within the utricle (gravity perception) and the saccule (hearing); the respective otoliths are the lapilli and the sagittae. Three such runs were subsequently carried out, using three different batches of fish. The runs were discontinued when the animals began to hatch. In the course of all three runs performed, CR led to larger than normal lapilli, whereas WVR

  15. Effects of Wall Vessel Rotation on the Growth of Larval Zebrafish Inner Ear Otoliths

    NASA Astrophysics Data System (ADS)

    Li, Xiaoyan; Anken, Ralf H.; Wang, Gaohong; Hilbig, Reinhard; Liu, Yongding

    2011-01-01

    Stimulus dependence is a general feature of developing sensory systems. It has been shown earlier that the growth of otoliths of late-stage Cichlid fish ( Oreochromis mossambicus) and Zebrafish ( Danio rerio) was slowed down by hypergravity, whereas microgravity during spaceflight yielded an opposite effect, i.e., larger than 1 g otoliths, in Swordtail ( Xiphophorus helleri) late-stage embryos. Using ground-based techniques to apply simulated weightlessness, long-term clinorotation (exposure on a fast-rotating clinostat with one axis of rotation for 7 days) led to larger than 1 g otoliths in late-stage Cichlid fish, which is fully in line with the results obtained on Swordtails from spaceflight. Hitherto, early-staged fish have not yet been subjected to (simulated or real) long-term (i.e., more than 3 or 4 days) weightlessness to investigate otolith growth. The present study was carried out in order to fill this gap. Therefore, we subjected Zebrafish at a somite-stage to Wall Vessel Rotation (WVR; a method regarded to provide simulated weightlessness), when the anlage of the inner ear already is present (10 h post fertilisation, hpf). Siblings were maintained under WVR for 3, 6, 9 and 12 days. Further short-term experiments (3 days) were carried out on 10 hpf animals as well as on very early larvae (1 K cell stage, 3 hpf) at two different rotation speeds. WVR (both rotation speeds) had no effect on otolith biogenesis in both stages as all otoliths were present after the experiments. In comparison with 1 g controls, WVR had significantly increased otolith growth (normalised by fish length) after 3 and 6 days of exposure, but significant differences of otolith growth between experimental animals and controls were not found after 9 and 12 days. In conclusion, WVR (at least within a time-span of exposure of up to 6 days) brings, comparable to the situation in real microgravity, a kind of feedback mechanism into action, resulting in larger otoliths. Later, possible

  16. Immobilized contrast-enhanced MRI: Gadolinium-based long-term MR contrast enhancement of the vein graft vessel wall.

    PubMed

    Mitsouras, Dimitris; Vemula, Praveen Kumar; Yu, Peng; Tao, Ming; Nguyen, Binh T; Campagna, Christina M; Karp, Jeffrey M; Mulkern, Robert V; Ozaki, C Keith; Rybicki, Frank J

    2011-01-01

    An implantable MR contrast agent that can be covalently immobilized on tissue during surgery has been developed. The rationale is that a durable increase in tissue contrast using an implantable contrast agent can enhance postsurgical tissue differentiation using MRI. For small-vessel (e.g., vein graft) MRI, the direct benefit of such permanent "labeling" of the vessel wall by modification of its relaxation properties is to achieve more efficient imaging. This efficiency can be realized as either increased contrast leading to more accurate delineation of vessel wall and lesion tissue boundaries, or, faster imaging without penalizing contrast-to-noise ratio, or a combination thereof. We demonstrate, for the first time, stable long-term MRI enhancement using such an exogenous contrast mechanism based on immobilizing a modified diethylenetriaminepentaacetic acid gadolinium(3+) dihydrogen complex on a human vein using a covalent amide bond. Signal enhancement due to the covalently immobilized contrast agent is demonstrated for excised human vein specimens imaged at 3 T, and its long-term stability is demonstrated during a 4-month incubation period.

  17. Histamine as an Endothelium-Derived Relaxing Factor in Aged Mesenteric Lymphatic Vessels.

    PubMed

    Nizamutdinova, Irina Tsoy; Maejima, Daisuke; Nagai, Takashi; Meininger, Cynthia J; Gashev, Anatoliy A

    2017-06-01

    Knowledge of the mechanisms by which aging affects contracting lymphatic vessels remains incomplete; therefore, the functional role of histamine in the reaction of aged lymphatic vessels to increases in flow remains unknown. We measured and analyzed parameters of lymphatic contractility in isolated and pressurized rat mesenteric lymphatic vessels (MLVs) obtained from 9- and 24-month Fischer-344 rats under control conditions and after pharmacological blockade of nitric oxide (NO) by Nω-Nitro-L-arginine methyl ester hydrochloride (L-NAME, 100 μM) or/and blockade of histamine production by α-methyl-DL-histidine dihydrochloride (α-MHD, 10 μM). We also quantitatively compared results of immunohistochemical labeling of the histamine-producing enzyme, histidine decarboxylase (HDC) in adult and aged MLVs. Our data provide the first demonstration of an increased functional role of histamine as an endothelial-derived relaxing factor in aged MLVs, which appears in parallel with the abolished role of NO in the reactions of these lymph vessels to increases in flow. In addition, we found an increased expression of HDC in endothelium of aged MLVs. Our findings provide the basis for better understanding of the processes of aging in lymphatic vessels and for setting new important directions for investigations of the aging-associated disturbances in lymph flow and the immune response.

  18. Nonlinear response of vessel walls due to short-time thermomechanical loading

    SciTech Connect

    Pfeiffer, P.A.; Kulak, R.F.

    1994-06-01

    Maintaining structural integrity of the reactor pressure vessel (RPV) during a postulated core melt accident is an important safety consideration in the design of the vessel. This study addresses the failure predictions of the vessel due to thermal and pressure loadings fro the molten core debris depositing on the lower head of the vessel. Different loading combinations were considered based on the dead load, yield stress assumptions, material response and internal pressurization. The analyses considered only short term failure (quasi static) modes, long term failure modes were not considered. Short term failure modes include plastic instabilities of the structure and failure due to exceeding the failure strain. Long term failure odes would be caused by creep rupture that leads to plastic instability of the structure. Due to the sort time durations analyzed, creep was not considered in the analyses presented.

  19. High-resolution MRI vessel wall imaging: spatial and temporal patterns of reversible cerebral vasoconstriction syndrome and central nervous system vasculitis.

    PubMed

    Obusez, E C; Hui, F; Hajj-Ali, R A; Cerejo, R; Calabrese, L H; Hammad, T; Jones, S E

    2014-08-01

    High-resolution MR imaging is an emerging tool for evaluating intracranial artery disease. It has an advantage of defining vessel wall characteristics of intracranial vascular diseases. We investigated high-resolution MR imaging arterial wall characteristics of CNS vasculitis and reversible cerebral vasoconstriction syndrome to determine wall pattern changes during a follow-up period. We retrospectively reviewed 3T-high-resolution MR imaging vessel wall studies performed on 26 patients with a confirmed diagnosis of CNS vasculitis and reversible cerebral vasoconstriction syndrome during a follow-up period. Vessel wall imaging protocol included black-blood contrast-enhanced T1-weighted sequences with fat suppression and a saturation band, and time-of-flight MRA of the circle of Willis. Vessel wall characteristics including enhancement, wall thickening, and lumen narrowing were collected. Thirteen patients with CNS vasculitis and 13 patients with reversible cerebral vasoconstriction syndrome were included. In the CNS vasculitis group, 9 patients showed smooth, concentric wall enhancement and thickening; 3 patients had smooth, eccentric wall enhancement and thickening; and 1 patient was without wall enhancement and thickening. Six of 13 patients had follow-up imaging; 4 patients showed stable smooth, concentric enhancement and thickening; and 2 patients had resoluton of initial imaging findings. In the reversible cerebral vasoconstriction syndrome group, 10 patients showed diffuse, uniform wall thickening with negligible-to-mild enhancement. Nine patients had follow-up imaging, with 8 patients showing complete resolution of the initial findings. Postgadolinium 3T-high-resolution MR imaging appears to be a feasible tool in differentiating vessel wall patterns of CNS vasculitis and reversible cerebral vasoconstriction syndrome changes during a follow-up period. © 2014 by American Journal of Neuroradiology.

  20. Proof test criteria for thin-walled 2219 aluminum pressure vessels. Volume 1: Program summary and data analysis

    NASA Technical Reports Server (NTRS)

    Finger, R. W.

    1976-01-01

    This experimental program was undertaken to investigate the crack growth behavior of deep surface flaws in 2219 aluminum. The program included tests of uniaxially loaded surface flaw and center crack panels at temperatures ranging from 20K (-423 F) to ambient. The tests were conducted on both the base metal and as-welded weld metal material. The program was designed to provide data on the mechanisms of failure by ligament penetration, and the residual cyclic life, after proof-testing, of a vessel which has been subjected to incipient penetration by the proof test. The results were compared and analyzed with previously developed data to develop guidelines for the proof testing of thin walled 2219 pressure vessels.

  1. Image-based biomechanical modeling of aortic wall stress and vessel deformation: response to pulsatile arterial pressure simulations

    NASA Astrophysics Data System (ADS)

    Hazer, Dilana; Bauer, Miriam; Unterhinninghofen, Roland; Dillmann, Rüdiger; Richter, Götz-M.

    2008-03-01

    Image-based modeling of cardiovascular biomechanics may be very helpful for patients with aortic aneurysms to predict the risk of rupture and evaluate the necessity of a surgical intervention. In order to generate a reliable support it is necessary to develop exact patient-specific models that simulate biomechanical parameters and provide individual structural analysis of the state of fatigue and characterize this to the potential of rupture of the aortic wall. The patient-specific geometry used here originates from a CT scan of an Abdominal Aortic Aneurysm (AAA). The computations are based on the Finite Element Method (FEM) and simulate the wall stress distribution and the vessel deformation. The wall transient boundary conditions are based on real time-dependent pressure simulations obtained from a previous computational fluid dynamics study. The physiological wall material properties consider a nonlinear hyperelastic constitutive model, based on realistic ex-vivo analysis of the aneurismal arterial tissue. The results showed complex deformation and stress distribution on the AAA wall. The maximum stresses occurred at the systole and are found around the aneurismal bulge in regions close to inflection points. Biomechanical modeling based on medical images and coupled with patient-specific hemodynamics allows analysing and quantifying the effects of dilatation of the arterial wall due to the pulsatile aortic pressure. It provides a physical and realistic insight into the wall mechanics and enables predictive simulations of AAA growth and assessment of rupture. Further development integrating endovascular models would help evaluating non-invasively individual treatment strategies for optimal placement and improved device design.

  2. Characterization of the vessel geometry, flow mechanics and wall shear stress in the great arteries of wildtype prenatal mouse.

    PubMed

    Yap, Choon Hwai; Liu, Xiaoqin; Pekkan, Kerem

    2014-01-01

    Abnormal fluid mechanical environment in the pre-natal cardiovascular system is hypothesized to play a significant role in causing structural heart malformations. It is thus important to improve our understanding of the prenatal cardiovascular fluid mechanical environment at multiple developmental time-points and vascular morphologies. We present such a study on fetal great arteries on the wildtype mouse from embryonic day 14.5 (E14.5) to near-term (E18.5). Ultrasound bio-microscopy (UBM) was used to measure blood velocity of the great arteries. Subsequently, specimens were cryo-embedded and sectioned using episcopic fluorescent image capture (EFIC) to obtain high-resolution 2D serial image stacks, which were used for 3D reconstructions and quantitative measurement of great artery and aortic arch dimensions. EFIC and UBM data were input into subject-specific computational fluid dynamics (CFD) for modeling hemodynamics. In normal mouse fetuses between E14.5-18.5, ultrasound imaging showed gradual but statistically significant increase in blood velocity in the aorta, pulmonary trunk (with the ductus arteriosus), and descending aorta. Measurement by EFIC imaging displayed a similar increase in cross sectional area of these vessels. However, CFD modeling showed great artery average wall shear stress and wall shear rate remain relatively constant with age and with vessel size, indicating that hemodynamic shear had a relative constancy over gestational period considered here. Our EFIC-UBM-CFD method allowed reasonably detailed characterization of fetal mouse vascular geometry and fluid mechanics. Our results suggest that a homeostatic mechanism for restoring vascular wall shear magnitudes may exist during normal embryonic development. We speculate that this mechanism regulates the growth of the great vessels.

  3. Characterizaton of the Vessel Geometry, Flow Mechanics and Wall Shear Stress in the Great Arteries of Wildtype Prenatal Mouse

    PubMed Central

    Yap, Choon Hwai; Liu, Xiaoqin; Pekkan, Kerem

    2014-01-01

    Introduction Abnormal fluid mechanical environment in the pre-natal cardiovascular system is hypothesized to play a significant role in causing structural heart malformations. It is thus important to improve our understanding of the prenatal cardiovascular fluid mechanical environment at multiple developmental time-points and vascular morphologies. We present such a study on fetal great arteries on the wildtype mouse from embryonic day 14.5 (E14.5) to near-term (E18.5). Methods Ultrasound bio-microscopy (UBM) was used to measure blood velocity of the great arteries. Subsequently, specimens were cryo-embedded and sectioned using episcopic fluorescent image capture (EFIC) to obtain high-resolution 2D serial image stacks, which were used for 3D reconstructions and quantitative measurement of great artery and aortic arch dimensions. EFIC and UBM data were input into subject-specific computational fluid dynamics (CFD) for modeling hemodynamics. Results In normal mouse fetuses between E14.5–18.5, ultrasound imaging showed gradual but statistically significant increase in blood velocity in the aorta, pulmonary trunk (with the ductus arteriosus), and descending aorta. Measurement by EFIC imaging displayed a similar increase in cross sectional area of these vessels. However, CFD modeling showed great artery average wall shear stress and wall shear rate remain relatively constant with age and with vessel size, indicating that hemodynamic shear had a relative constancy over gestational period considered here. Conclusion Our EFIC-UBM-CFD method allowed reasonably detailed characterization of fetal mouse vascular geometry and fluid mechanics. Our results suggest that a homeostatic mechanism for restoring vascular wall shear magnitudes may exist during normal embryonic development. We speculate that this mechanism regulates the growth of the great vessels. PMID:24475188

  4. Transient Non-Newtonian Blood Flow under Magnetic Targeting Drug Delivery in an Aneurysm Blood Vessel with Porous Walls

    NASA Astrophysics Data System (ADS)

    Alimohamadi, Haleh; Imani, Mohsen

    2014-11-01

    The present investigation deals with numerical solution of blood flow patterns through an aneurysm artery under the applied magnetic field. Transient extended Navier-Stokes, Brinkman, continuity, and heat conduction equations govern this phenomenon and unsteady pulsatile inlet velocity varies by human heart-beating frequency. Our simulation demonstrates applying 105 magnetic field intensity (MnF) to recirculate flow and increase fluid flux and maximum blood temperature by 62.5x and 3.5%, respectively, in the aneurysm region. It is also shown that the vessel's wall porosity plays an important role in magnetic targeting of drug delivery performance, as this parameter can noticeably change maximum blood temperature and pressure.

  5. Development of a sensitive experimental set-up for LIF fuel wall film measurements in a pressure vessel

    NASA Astrophysics Data System (ADS)

    Schulz, Florian; Schmidt, Jürgen; Beyrau, Frank

    2015-05-01

    This paper focusses on fundamental investigations of fuel wall films, which are formed when the spray impinges on the piston or cylinder walls. To reproduce the wide range of operating conditions within homogeneously charged gasoline direct-injection engines, it is necessary to use a film thickness measurement method, which can be applied inside a high-pressure, high-temperature vessel. Hence, we developed a method based on laser-induced fluorescence that reaches: a precision better than 1 µm, a geometric resolution of 31 µm and a practical applicability for wall film thicknesses smaller 80 µm. To obtain accurate film thickness results, we provide a detailed description of the selection of the surrogate fuel isooctane with 3-pentanone as fluorescence tracer and the resulting assembly of the excitation source, beam expander, filters, camera and the essential image processing. Furthermore, advantages and disadvantages of other possible solutions are discussed. Earlier publications provide only little information about the accuracy of their calibration and measurement procedures. Therefore, we tested and compared three basic calibration methods to each other and provide an analysis of possible errors, such as the influence of the preferential evaporation of 3-pentanone. Finally, images of resulting wall films are presented, and practical considerations for the execution of the measurements like recording timings are discussed.

  6. Target tracking by distributed autonomous vessels using the derivative-free nonlinear Kalman filter

    NASA Astrophysics Data System (ADS)

    Rigatos, Gerasimos; Siano, Pierluigi; Raffo, Guilerme

    2015-12-01

    In this paper a distributed control problem for unmanned surface vessels (USVs) is formulated as follows: there are N USVs which pursue another vessel (moving target). At each time instant each USV can obtain measurements of the target's cartesian coordinates. The objective is to make the USVs converge in a synchronized manner towards the target, while avoiding collisions between them and avoiding collisions with obstacles in their motion plane. A distributed control law is developed for the USVs which enables not only convergence of the USVs to the goal position, but also makes possible to maintain the cohesion of the USVs fleet. Moreover, distributed filtering is performed, so as to obtain an estimate of the target vessel's state vector. This provides the desirable state vector to be tracked by each one of the USVs. To this end, a new distributed nonlinear filtering method of improved accuracy and computation speed is introduced. This filtering approach, under the name Derivative-free distributed nonlinear Kalman Filter is based on differential flatness theory and on an exact linearization of the target vessel's dynamic/kinematic model.

  7. Small Diameter Blood Vessels Bioengineered From Human Adipose-derived Stem Cells

    PubMed Central

    Zhou, Renpeng; Zhu, Lei; Fu, Shibo; Qian, Yunliang; Wang, Danru; Wang, Chen

    2016-01-01

    Bioengineering of small-diameter blood vessels offers a promising approach to reduce the morbidity associated with coronary artery and peripheral vascular disease. The aim of this study was to construct a two-layered small-diameter blood vessel using smooth muscle cells (SMCs) and endothelial cells (ECs) differentiated from human adipose-derived stem cells (hASCs). The outer layer was constructed with biodegradable polycaprolactone (PCL)-gelatin mesh seeded with SMCs, and this complex was then rolled around a silicone tube under pulsatile stimulation. After incubation for 6 to 8 weeks, the PCL-gelatin degraded and the luminal supporting silicone tube was removed. The smooth muscle layer was subsequently lined with ECs differentiated from hASCs after stimulation with VEGF and BMP4 in combination hypoxia. The phenotype of differentiated SMCs and ECs, and the cytotoxicity of the scaffold and biomechanical assessment were analyzed. Our results demonstrated that the two-layered bioengineered vessels exhibited biomechanical properties similar to normal human saphenous veins (HSV). Therefore, hASCs provide SMCs and ECs for bioengineering of small-diameter blood vessels. PMID:27739487

  8. Robust Retinal Vessel Segmentation via Locally Adaptive Derivative Frames in Orientation Scores.

    PubMed

    Zhang, Jiong; Dashtbozorg, Behdad; Bekkers, Erik; Pluim, Josien P W; Duits, Remco; Ter Haar Romeny, Bart M

    2016-12-01

    This paper presents a robust and fully automatic filter-based approach for retinal vessel segmentation. We propose new filters based on 3D rotating frames in so-called orientation scores, which are functions on the Lie-group domain of positions and orientations [Formula: see text]. By means of a wavelet-type transform, a 2D image is lifted to a 3D orientation score, where elongated structures are disentangled into their corresponding orientation planes. In the lifted domain [Formula: see text], vessels are enhanced by means of multi-scale second-order Gaussian derivatives perpendicular to the line structures. More precisely, we use a left-invariant rotating derivative (LID) frame, and a locally adaptive derivative (LAD) frame. The LAD is adaptive to the local line structures and is found by eigensystem analysis of the left-invariant Hessian matrix (computed with the LID). After multi-scale filtering via the LID or LAD in the orientation score domain, the results are projected back to the 2D image plane giving us the enhanced vessels. Then a binary segmentation is obtained through thresholding. The proposed methods are validated on six retinal image datasets with different image types, on which competitive segmentation performances are achieved. In particular, the proposed algorithm of applying the LAD filter on orientation scores (LAD-OS) outperforms most of the state-of-the-art methods. The LAD-OS is capable of dealing with typically difficult cases like crossings, central arterial reflex, closely parallel and tiny vessels. The high computational speed of the proposed methods allows processing of large datasets in a screening setting.

  9. The source of NMR-detected motional anisotropy of water in blood vessel walls.

    PubMed Central

    Sharf, Y; Knubovets, T; Dayan, D; Hirshberg, A; Akselrod, S; Navon, G

    1997-01-01

    2H Double quantum-filtered (DQF) NMR spectroscopy of deuterated water is sensitive to the presence of order in biological systems. This is because the only nuclei that are detected are those with residual quadrupolar interactions due to their anisotropic motion. In the present study, samples of aorta, coronary and carotid arteries, and vena cava were studied in parallel by 2H DQF NMR and by light microscopy. The average quadrupolar splitting, calculated from the NMR data, varies considerably among the different blood vessels, with high reproducibility for each type of vessel. Polarization microscopy examinations using collagen-specific staining with picrosirius red, have shown a variety of color profiles for the different blood vessels. These reflect different physical modes of aggregation (packing and thickness) of collagen fibers. A correlation was found between the NMR parameters and the color profiles of the picrosirius red-stained sections. Treating the blood vessels with 90% formic acid resulted in the elimination of the 2H DQF NMR signal. Histological analysis demonstrated a complete degradation of collagen and muscle, whereas the elastin filaments were preserved. Evidence is given that the 2H DQF NMR signal is dominated by the contribution of water molecules interacting with the collagen fibers. Images FIGURE 3 PMID:9284287

  10. Active push deployment technique improves stent/vessel-wall interaction in endovascular treatment of acute stroke with stent retrievers.

    PubMed

    Wiesmann, Martin; Brockmann, Marc-Alexander; Heringer, Sarah; Müller, Marguerite; Reich, Arno; Nikoubashman, Omid

    2017-03-01

    The optimal interaction between stent struts and thrombus is crucial for successful revascularization in endovascular stroke therapy with stent retrievers. Deploying the stent retriever by actively pushing it into the thrombus increases the radial force with which the stent struts expand into the thrombus. To examine the active push deployment (APD) technique in an in vitro model and present our clinical experience with this technique. In an in vitro experiment we investigated the configuration of a Solitaire and a Trevo ProVue device (both 4×20 mm), depending on whether the devices were deployed using the APD technique or simple unsheathing. We retrospectively assessed the effectiveness and safety of this technique by analyzing 130 patients with large vessel occlusions (carotid T or M1 segment of the middle cerebral artery), who received endovascular treatment with a Trevo device (4×20 mm) that was deployed using the APD technique. In vitro experiment: the APD technique improved apposition of the devices to the vessel wall. There was widening of 30% (Trevo) and 19% (Solitaire) at the cost of a shortening of 5% and 4%, respectively, when the devices were deployed in a carotid T model. Clinical study: the revascularization rate (Thrombolysis in Cerebral Infarction ≥2b) with the Trevo device was 90%. There were no retriever-associated dissections or perforations in 278 retrieval maneuvers. The APD technique improves apposition of the tested devices to the vessel wall. The widening effect comes at the cost of minimal shortening of the devices. Our clinical experience shows that using the APD technique to deploy the Trevo device is effective and safe. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

  11. Suppression of tumor growth by novel peptides homing to tumor-derived new blood vessels.

    PubMed

    Asai, Tomohiro; Nagatsuka, Mayumi; Kuromi, Koichi; Yamakawa, Satoru; Kurohane, Kohta; Ogino, Koichi; Tanaka, Michinori; Taki, Takao; Oku, Naoto

    2002-01-16

    Novel peptides homing to angiogenic vessels were recently isolated from a phage-displayed random pentadecapeptide library. One of the isolated peptides, ASSSYPLIHWRPWAR, significantly suppressed the migration of VEGF-stimulated human umbilical vein endothelial cells. Dendoric ASSSYPLIHWRPWAR-peptide suppressed the formation of new blood vessels in dorsal air sac model mice. Furthermore, ASSSYPLIHWRPWAR-peptide and the fragment peptides containing WRP, which is revealed to be an epitope sequence, significantly suppressed the tumor growth, although 15-mer shuffled peptide derived from ASSSYPLIHWRPWAR and pentapeptides with alanine substitution of each residue of WRP did not. Taken together, ASSSYPLIHWRPWAR-peptide may cause tumor dormancy through inhibition of angiogenesis, and the WRP sequence may be the minimal and essential sequence for this activity.

  12. Optical coherence tomography assessment of vessel wall degradation in thoracic aortic aneurysms

    NASA Astrophysics Data System (ADS)

    Real, Eusebio; Eguizabal, Alma; Pontón, Alejandro; Díez, Marta Calvo; Fernando Val-Bernal, José; Mayorga, Marta; Revuelta, José M.; López-Higuera, José M.; Conde, Olga M.

    2013-12-01

    Optical coherence tomography images of human thoracic aorta from aneurysms reveal elastin disorders and smooth muscle cell alterations when visualizing the media layer of the aortic wall. These disorders can be employed as indicators for wall degradation and, therefore, become a hallmark for diagnosis of risk of aneurysm under intraoperative conditions. Two approaches are followed to evaluate this risk: the analysis of the reflectivity decay along the penetration depth and the textural analysis of a two-dimensional spatial distribution of the aortic wall backscattering. Both techniques require preprocessing stages for the identification of the air-sample interface and for the segmentation of the media layer. Results show that the alterations in the media layer of the aortic wall are better highlighted when the textural approach is considered and also agree with a semiquantitative histopathological grading that assesses the degree of wall degradation. The correlation of the co-occurrence matrix attains a sensitivity of 0.906 and specificity of 0.864 when aneurysm automatic diagnosis is evaluated with a receiver operating characteristic curve.

  13. Fish scale-derived collagen patch promotes growth of blood and lymphatic vessels in vivo.

    PubMed

    Wang, Jun Kit; Yeo, Kim Pin; Chun, Yong Yao; Tan, Timothy Thatt Yang; Tan, Nguan Soon; Angeli, Véronique; Choong, Cleo

    2017-09-06

    In this study, Type I collagen was extracted from fish scales as a potential alternative source of collagen for tissue engineering applications. Since unmodified collagen typically has poor mechanical and degradation stability both in vitro and in vivo, additional methylation modification and 1,4-butanediol diglycidyl ether (BDE) crosslinking steps were used to improve the physicochemical properties of fish scale-derived collagen. Subsequently, in vivo studies using a murine model demonstrated the biocompatibility of the different fish scale-derived collagen patches. In general, favorable integration of the collagen patches to the surrounding tissues, with good infiltration of cells, blood vessels (BVs) and lymphatic vessels (LVs) were observed under growth factor-free conditions. Interestingly, significantly higher (p < 0.05) number of LVs was found to be more abundant around collagen patches with methylation modification and BDE crosslinking. Overall, we have demonstrated the potential application of fish scale-derived collagen as a promising scaffolding material for various biomedical applications. Currently the most common sources of collagen are of bovine and porcine origins, although the industrial use of collagen obtained from non-mammalian species is growing in importance, particularly since they have a lower risk of disease transmission and are not subjected to any cultural or religious constraints. However, unmodified collagen typically has poor mechanical and degradation stability both in vitro and in vivo. Hence, in this study, Type I collagen was successfully extracted from fish scales and chemically modified and crosslinked. In vitro studies showed overall improvement in the physicochemical properties of the material, whilst in vivo implantation studies showed improvements in the growth of blood and lymphatic host vessels in the vicinity of the implants. Copyright © 2017. Published by Elsevier Ltd.

  14. 1-Dimensional simulation of thermal annealing in a commercial nuclear power plant reactor pressure vessel wall section

    SciTech Connect

    Nakos, J.T.; Rosinski, S.T.; Acton, R.U.

    1994-11-01

    The objective of this work was to provide experimental heat transfer boundary condition and reactor pressure vessel (RPV) section thermal response data that can be used to benchmark computer codes that simulate thermal annealing of RPVS. This specific protect was designed to provide the Electric Power Research Institute (EPRI) with experimental data that could be used to support the development of a thermal annealing model. A secondary benefit is to provide additional experimental data (e.g., thermal response of concrete reactor cavity wall) that could be of use in an annealing demonstration project. The setup comprised a heater assembly, a 1.2 in {times} 1.2 m {times} 17.1 cm thick [4 ft {times} 4 ft {times} 6.75 in] section of an RPV (A533B ferritic steel with stainless steel cladding), a mockup of the {open_quotes}mirror{close_quotes} insulation between the RPV and the concrete reactor cavity wall, and a 25.4 cm [10 in] thick concrete wall, 2.1 in {times} 2.1 in [10 ft {times} 10 ft] square. Experiments were performed at temperature heat-up/cooldown rates of 7, 14, and 28{degrees}C/hr [12.5, 25, and 50{degrees}F/hr] as measured on the heated face. A peak temperature of 454{degrees}C [850{degrees}F] was maintained on the heated face until the concrete wall temperature reached equilibrium. Results are most representative of those RPV locations where the heat transfer would be 1-dimensional. Temperature was measured at multiple locations on the heated and unheated faces of the RPV section and the concrete wall. Incident heat flux was measured on the heated face, and absorbed heat flux estimates were generated from temperature measurements and an inverse heat conduction code. Through-wall temperature differences, concrete wall temperature response, heat flux absorbed into the RPV surface and incident on the surface are presented. All of these data are useful to modelers developing codes to simulate RPV annealing.

  15. NADPH oxidase-derived ROS and the regulation of pulmonary vessel tone

    PubMed Central

    Frazziano, G.; Champion, H. C.

    2012-01-01

    Pulmonary vessel constriction results from an imbalance between vasodilator and vasoconstrictor factors released by the endothelium including nitric oxide, endothelin, prostanoids, and reactive oxygen species (ROS). ROS, generated by a variety of enzymatic sources (such as mitochondria and NADPH oxidases, a.k.a. Nox), appear to play a pivotal role in vascular homeostasis, whereas elevated levels effect vascular disease. The pulmonary circulation is very sensitive to changes in the partial pressure of oxygen and differs from the systemic circulation in its response to this change. In fact, the pulmonary vessels contract in response to low oxygen tension, whereas systemic vessels dilate. Growing evidence suggests that ROS production and ROS-related pathways may be key factors that underlie this differential response to oxygen tension. A major emphasis of our laboratory is the role of Nox isozymes in cardiovascular disease. In this review, we will focus our attention on the role of Nox-derived ROS in the control of pulmonary vascular tone. PMID:22427511

  16. Selective enhancement filters for nodules, vessels, and airway walls in two- and three-dimensional CT scans.

    PubMed

    Li, Qiang; Sone, Shusuke; Doi, Kunio

    2003-08-01

    Computer-aided diagnostic (CAD) schemes have been developed to assist radiologists in the early detection of lung cancer in radiographs and computed tomography (CT) images. In order to improve sensitivity for nodule detection, many researchers have employed a filter as a preprocessing step for enhancement of nodules. However, these filters enhance not only nodules, but also other anatomic structures such as ribs, blood vessels, and airway walls. Therefore, nodules are often detected together with a large number of false positives caused by these normal anatomic structures. In this study, we developed three selective enhancement filters for dot, line, and plane which can simultaneously enhance objects of a specific shape (for example, dot-like nodules) and suppress objects of other shapes (for example, line-like vessels). Therefore, as preprocessing steps, these filters would be useful for improving the sensitivity of nodule detection and for reducing the number of false positives. We applied our enhancement filters to synthesized images to demonstrate that they can selectively enhance a specific shape and suppress other shapes. We also applied our enhancement filters to real two-dimensional (2D) and three-dimensional (3D) CT images to show their effectiveness in the enhancement of specific objects in real medical images. We believe that the three enhancement filters developed in this study would be useful in the computerized detection of cancer in 2D and 3D medical images.

  17. Erythroid cell growth and differentiation in vitro in the simulated microgravity environment of the NASA rotating wall vessel bioreactor

    NASA Technical Reports Server (NTRS)

    Sytkowski, A. J.; Davis, K. L.

    2001-01-01

    Prolonged exposure of humans and experimental animals to the altered gravitational conditions of space flight has adverse effects on the lymphoid and erythroid hematopoietic systems. Although some information is available regarding the cellular and molecular changes in lymphocytes exposed to microgravity, little is known about the erythroid cellular changes that may underlie the reduction in erythropoiesis and resultant anemia. We now report a reduction in erythroid growth and a profound inhibition of erythropoietin (Epo)-induced differentiation in a ground-based simulated microgravity model system. Rauscher murine erythroleukemia cells were grown either in tissue culture vessels at 1 x g or in the simulated microgravity environment of the NASA-designed rotating wall vessel (RWV) bioreactor. Logarithmic growth was observed under both conditions; however, the doubling time in simulated microgravity was only one-half of that seen at 1 x g. No difference in apoptosis was detected. Induction with Epo at the initiation of the culture resulted in differentiation of approximately 25% of the cells at 1 x g, consistent with our previous observations. In contrast, induction with Epo at the initiation of simulated microgravity resulted in only one-half of this degree of differentiation. Significantly, the growth of cells in simulated microgravity for 24 h prior to Epo induction inhibited the differentiation almost completely. The results suggest that the NASA RWV bioreactor may serve as a suitable ground-based microgravity simulator to model the cellular and molecular changes in erythroid cells observed in true microgravity.

  18. Erythroid cell growth and differentiation in vitro in the simulated microgravity environment of the NASA rotating wall vessel bioreactor.

    PubMed

    Sytkowski, A J; Davis, K L

    2001-02-01

    Prolonged exposure of humans and experimental animals to the altered gravitational conditions of space flight has adverse effects on the lymphoid and erythroid hematopoietic systems. Although some information is available regarding the cellular and molecular changes in lymphocytes exposed to microgravity, little is known about the erythroid cellular changes that may underlie the reduction in erythropoiesis and resultant anemia. We now report a reduction in erythroid growth and a profound inhibition of erythropoietin (Epo)-induced differentiation in a ground-based simulated microgravity model system. Rauscher murine erythroleukemia cells were grown either in tissue culture vessels at 1 x g or in the simulated microgravity environment of the NASA-designed rotating wall vessel (RWV) bioreactor. Logarithmic growth was observed under both conditions; however, the doubling time in simulated microgravity was only one-half of that seen at 1 x g. No difference in apoptosis was detected. Induction with Epo at the initiation of the culture resulted in differentiation of approximately 25% of the cells at 1 x g, consistent with our previous observations. In contrast, induction with Epo at the initiation of simulated microgravity resulted in only one-half of this degree of differentiation. Significantly, the growth of cells in simulated microgravity for 24 h prior to Epo induction inhibited the differentiation almost completely. The results suggest that the NASA RWV bioreactor may serve as a suitable ground-based microgravity simulator to model the cellular and molecular changes in erythroid cells observed in true microgravity.

  19. Histochemical Evaluation of the Vessel Wall Destruction and Selectivity After Treatment with Intense Pulsed Light in Capillary Malformations.

    PubMed

    Grillo, E; Rita Travassos, A; Boixeda, P; Cuevas, A; Pérez, B; Paoli, J; Jaén, P

    2016-04-01

    Among the different approaches for improving the effectiveness in the treatment of Capillary Malformations type Port Wine Stain (CM type PWS) are the intense pulsed light sources. There are few clinical studies prove useful in the treatment of CM. Furthermore, no studies have been published yet demonstrating the histological effects of IPL in CM. To assess the histological effects of pulsed light in capillary malformations type port wine stain. We wanted to compare epidermal, dermal and vessel wall damage after treatment with different combinations of IPL parameters. Fifty-five post-treatment biopsies were performed in 15 consenting patients with CM and stained with nitroblue-tetrazolium chloride (NBTC). Patients had not been treated previously. Fifteen patients with CM, with a median age of 39 years-old were enrolled in this study. In this series, the patients with the most severe epidermal damage were those with a darker phototype. Pink CM were especially resistant to treatment, even using high fluences, short pulse durations and stacking pulses. Longer intra- and interpulse delays were effective in purple CM, achieving adequate vessel destruction. IPL devices provide a vast amount of treatment possibilities and further studies are necessary to optimize therapeutic approaches to CM. In this study we have observed the histological effects of different pulses on the MC type PWS. Copyright © 2015 AEDV. Published by Elsevier España, S.L.U. All rights reserved.

  20. Erythroid cell growth and differentiation in vitro in the simulated microgravity environment of the NASA rotating wall vessel bioreactor

    NASA Technical Reports Server (NTRS)

    Sytkowski, A. J.; Davis, K. L.

    2001-01-01

    Prolonged exposure of humans and experimental animals to the altered gravitational conditions of space flight has adverse effects on the lymphoid and erythroid hematopoietic systems. Although some information is available regarding the cellular and molecular changes in lymphocytes exposed to microgravity, little is known about the erythroid cellular changes that may underlie the reduction in erythropoiesis and resultant anemia. We now report a reduction in erythroid growth and a profound inhibition of erythropoietin (Epo)-induced differentiation in a ground-based simulated microgravity model system. Rauscher murine erythroleukemia cells were grown either in tissue culture vessels at 1 x g or in the simulated microgravity environment of the NASA-designed rotating wall vessel (RWV) bioreactor. Logarithmic growth was observed under both conditions; however, the doubling time in simulated microgravity was only one-half of that seen at 1 x g. No difference in apoptosis was detected. Induction with Epo at the initiation of the culture resulted in differentiation of approximately 25% of the cells at 1 x g, consistent with our previous observations. In contrast, induction with Epo at the initiation of simulated microgravity resulted in only one-half of this degree of differentiation. Significantly, the growth of cells in simulated microgravity for 24 h prior to Epo induction inhibited the differentiation almost completely. The results suggest that the NASA RWV bioreactor may serve as a suitable ground-based microgravity simulator to model the cellular and molecular changes in erythroid cells observed in true microgravity.

  1. Computational blood flow and vessel wall modeling in a CT-based thoracic aorta after stent-graft implantation

    NASA Astrophysics Data System (ADS)

    Hazer, Dilana; Stoll, Markus; Schmidt, Eduard; Richter, Goetz-M.; Dillmann, Rüdiger

    2010-03-01

    Abnormal blood flow conditions and structural fatigue within stented vessels may lead to undesired failure causing death to the patient. Image-based computational modeling provides a physical and realistic insight into the patientspecific biomechanics and enables accurate predictive simulations of development, growth and failure of cardiovascular diseases as well as associated risks. Controlling the efficiency of an endovascular treatment is necessary for the evaluation of potential complications and predictions on the assessment of the pathological state. In this paper we investigate the effects of stent-graft implantation on the biomechanics in a patient-specific thoracic aortic model. The patient geometry and the implanted stent-graft are obtained from morphological data based on a CT scan performed during a controlling routine. Computational fluid dynamics (CFD) and computational structure mechanics (CSM) simulations are conducted based on the finite volume method (FVM) and on the finite element method (FEM) to compute the hemodynamics and the elastomechanics within the aortic model, respectively. Physiological data based on transient pressure and velocity profiles are used to set the necessary boundary conditions. Further, the effects of various boundary conditions and definition of contact interactions on the numerical stability of the blood flow and the vessel wall simulation results are also investigated. The quantification of the hemodynamics and the elastomechanics post endovascular intervention provides a realistic controlling of the state of the stented vessel and of the efficiency of the therapy. Consequently, computational modeling would help in evaluating individual therapies and optimal treatment strategies in the field of minimally invasive endovascular surgery.

  2. Measurements of Escaping Fast Ions at the DIII-D Vessel Wall

    NASA Astrophysics Data System (ADS)

    Pickering, L. D.; Heidbrink, W. W.; Zhu, Y.

    2006-10-01

    The loss of fast ions is detected by two pairs of thin foil Faraday collectors [1] that are installed just behind the graphite first wall in a vacuum port. Collimating apertures select fast ions that have energies >10 keV and that travel either with or against the plasma current. The strong correlation of beam-ion loss detector (BILD) signals with neutral beam modulation shows that, under appropriate conditions, prompt losses from nearly every beam source are detected. Orbit calculations indicate that the correlation occurs when injected neutrals are deposited at a location that “connects” with an orbit observed by the detector; as expected, these correlations depend strongly on plasma current. In addition to these classical effects, enhanced signals sometimes occur during ion cyclotron heating (presumably due to parametric decay instabilities) and during Alfvén activity (due to transport by the instabilities). 6pt[1] F.E. Cecil, et al., Rev. Sci. Instrum. 74, 1747 (2003).

  3. Mechanisms of Nitrite Reduction to Nitric Oxide in the Heart and Vessel Wall

    PubMed Central

    Zweier, Jay L.; Li, Haitao; Samouilov, Alexandre; Liu, Xiaoping

    2010-01-01

    Nitric oxide (NO) is an important regulator of a variety of biological functions, and also has a role in the pathogenesis of cellular injury. It had been generally accepted that NO is solely generated in biological tissues by specific nitric oxide synthases (NOS) which metabolize arginine to citrulline with the formation of NO. However, over the last 15 years, nitrite-mediated NO production has been shown to be an important mechanism of NO formation in the heart and cardiovascular system. Now numerous studies have demonstrated that nitrite can be an important source rather than simply a product of NO in mammalian cells and tissues and can be a potential vasodilator drug for cardiovascular diseases. There are a variety of mechanisms of nitrite reduction to NO and it is now appreciated that this process, while enhanced under hypoxic conditions, also occurs under normoxia. Several methods, including electron paramagnetic resonance, chemiluminescence NO analyzer, and NO-electrode have been utilized to measure, quantitate, and image nitrite-mediated NO formation. Results reveal that nitrite-dependent NO generation plays critical physiological and pathological roles, and is controlled by oxygen tension, pH, reducing substrates and nitrite levels. In this manuscript, we review the mechanisms of nitrite–mediated NO formation and the effects of oxygen on this process with a focus on how this occurs in the heart and vessels. PMID:20044016

  4. Protein-Bound Uremic Toxins Stimulate Crosstalk between Leukocytes and Vessel Wall

    PubMed Central

    Glorieux, Griet; Schepers, Eva; Cohen, Gerald; Gondouin, Bertrand; Van Landschoot, Maria; Eloot, Sunny; Rops, Angelique; Van de Voorde, Johan; De Vriese, An; van der Vlag, Johan; Brunet, Philippe; Van Biesen, Wim; Vanholder, Raymond

    2013-01-01

    Leukocyte activation and endothelial damage both contribute to cardiovascular disease, a major cause of morbidity and mortality in CKD. Experimental in vitro data link several protein-bound uremic retention solutes to the modulation of inflammatory stimuli, including endothelium and leukocyte responses and cardiovascular damage, corroborating observational in vivo data. However, the impact of these uremic toxins on the crosstalk between endothelium and leukocytes has not been assessed. This study evaluated the effects of acute and continuous exposure to uremic levels of indoxylsulfate (IS), p-cresylsulfate (pCS), and p-cresylglucuronide (pCG) on the recruitment of circulating leukocytes in the rat peritoneal vascular bed using intravital microscopy. Superfusion with IS induced strong leukocyte adhesion, enhanced extravasation, and interrupted blood flow, whereas pCS caused a rapid increase in leukocyte rolling. Superfusion with pCS and pCG combined caused impaired blood flow and vascular leakage but did not further enhance leukocyte rolling over pCS alone. Intravenous infusion with IS confirmed the superfusion results and caused shedding of heparan sulfate, pointing to disruption of the glycocalyx as the mechanism likely mediating IS-induced flow stagnation. These results provide the first clear in vivo evidence that IS, pCS, and pCG exert proinflammatory effects that contribute to vascular damage by stimulating crosstalk between leukocytes and vessels. PMID:24009240

  5. Protein-bound uremic toxins stimulate crosstalk between leukocytes and vessel wall.

    PubMed

    Pletinck, Anneleen; Glorieux, Griet; Schepers, Eva; Cohen, Gerald; Gondouin, Bertrand; Van Landschoot, Maria; Eloot, Sunny; Rops, Angelique; Van de Voorde, Johan; De Vriese, An; van der Vlag, Johan; Brunet, Philippe; Van Biesen, Wim; Vanholder, Raymond

    2013-12-01

    Leukocyte activation and endothelial damage both contribute to cardiovascular disease, a major cause of morbidity and mortality in CKD. Experimental in vitro data link several protein-bound uremic retention solutes to the modulation of inflammatory stimuli, including endothelium and leukocyte responses and cardiovascular damage, corroborating observational in vivo data. However, the impact of these uremic toxins on the crosstalk between endothelium and leukocytes has not been assessed. This study evaluated the effects of acute and continuous exposure to uremic levels of indoxylsulfate (IS), p-cresylsulfate (pCS), and p-cresylglucuronide (pCG) on the recruitment of circulating leukocytes in the rat peritoneal vascular bed using intravital microscopy. Superfusion with IS induced strong leukocyte adhesion, enhanced extravasation, and interrupted blood flow, whereas pCS caused a rapid increase in leukocyte rolling. Superfusion with pCS and pCG combined caused impaired blood flow and vascular leakage but did not further enhance leukocyte rolling over pCS alone. Intravenous infusion with IS confirmed the superfusion results and caused shedding of heparan sulfate, pointing to disruption of the glycocalyx as the mechanism likely mediating IS-induced flow stagnation. These results provide the first clear in vivo evidence that IS, pCS, and pCG exert proinflammatory effects that contribute to vascular damage by stimulating crosstalk between leukocytes and vessels.

  6. Endoglin is required in Pax3-derived cells for embryonic blood vessel formation.

    PubMed

    Young, K; Krebs, L T; Tweedie, E; Conley, B; Mancini, M; Arthur, H M; Liaw, L; Gridley, T; Vary, C P H

    2016-01-01

    Mutations in endoglin, a TGFβ/BMP coreceptor, are causal for hereditary hemorrhagic telangiectasia (HHT). Endoglin-null (Eng-/-) mouse embryos die at embryonic day (E)10.5-11.5 due to defects in angiogenesis. In part, this is due to an absence of vascular smooth muscle cell differentiation and vessel investment. Prior studies from our lab and others have shown the importance of endoglin expression in embryonic development in both endothelial cells and neural crest stem cells. These studies support the hypothesis that endoglin may play cell-autonomous roles in endothelial and vascular smooth muscle cell precursors. However, the requirement for endoglin in vascular cell precursors remains poorly defined. Our objective was to specifically delete endoglin in neural crest- and somite-derived Pax3-positive vascular precursors to understand the impact on somite progenitor cell contribution to embryonic vascular development. Pax3Cre mice were crossed with Eng+/- mice to obtain compound mutant Pax3(Cre/+);Eng+/- mice. These mice were then crossed with homozygous endoglin LoxP-mutated (Eng(LoxP/LoxP)) mice to conditionally delete the endoglin gene in specific lineages that contribute to endothelial and smooth muscle constituents of developing embryonic vessels. Pax3(Cre/+);Eng(LoxP/)(-) mice showed a variety of vascular defects at E10.5, and none of these mice survived past E12.5. Embryos analyzed at E10.5 showed malformations suggestive of misdirection of the intersomitic vessels. The dorsal aorta showed significant dilation with associated vascular smooth muscle cells exhibiting disorganization and enhanced expression of smooth muscle differentiation proteins, including smooth muscle actin. These results demonstrate a requirement for endoglin in descendants of Pax3-expressing vascular cell precursors, and thus provides new insight into the cellular basis underlying adult vascular diseases such as HHT. Copyright © 2015 Elsevier Inc. All rights reserved.

  7. Development of automated welding process for field fabrication of thick walled pressure vessels. Fourth quarter technical progress report for period ending September 28, 1980

    SciTech Connect

    Not Available

    1980-01-01

    Progress is reported in research aimed at optimizing an automated welding process for the field fabrication of thick-walled pressure vessels and for evaluating the welded joints. Information is included on the welding equipment, mechanical control of the process, joint design, filler wire optimization, in-process nondestructive testing of welds, and repair techniques. (LCL)

  8. A 32-channel coil system for MR vessel wall imaging of intracranial and extracranial arteries at 3T.

    PubMed

    Hu, Xiaoqing; Li, Ye; Zhang, Lei; Zhang, Xiaoliang; Liu, Xin; Chung, Yiu-Cho

    2017-02-01

    To develop a RF coil system for joint imaging of intracranial and extracranial arterial vessel wall at 3T. The coil system consists of a 24-channel head coil combined with an 8-channel carotid coil. It is compared with a standard coil configuration (12-channel head coil+4-channel neck coil+8-channel carotid coil) for SNR and g-factors in phantoms and healthy volunteers. The clinical relevance of the proposed coil system is also evaluated in patients. In phantom experiments, the SNR of the proposed coil system is 53% higher than the maximum SNR of the standard coil configuration at the center of the phantom which usually corresponds to the intracranial region of the head. The g-factors of the proposed coil system in the sagittal plane are lower than the standard coil configuration (by 10.8% and 26.6% for R=2 and 4 respectively) in the same experiment. In healthy volunteer experiments, 55% of the pixels have SNR above 100 for the proposed coil system, which is 33% more than that of the standard coil configuration. The maximum g-factors in the standard configuration are higher than those from the new coil design by 12% at R=2 and up to 36% at R=4 in the sagittal plane. In patients, in-vivo intracranial and extracranial arterial wall images at an isotropic spatial resolution of 0.6mm can be acquired using the proposed coil system. Plaques are well depicted from the images. The performance of the proposed coil set is superior to the standard coil configuration, providing high SNR, low g-factor and good spatial coverage needed for simultaneous high resolution imaging of intracranial and extracranial arterial walls. Images acquired in 7.6min using the proposed coil system can achieve an isotropic spatial resolution of 0.6mm and can be used to depict plaques on the intracranial and extracranial arterial walls in patients. Copyright © 2016 Elsevier Inc. All rights reserved.

  9. Viscous flow through slowly expanding or contracting porous walls with low seepage Reynolds number: a model for transport of biological fluids through vessels.

    PubMed

    Dinarvand, Saeed

    2011-10-01

    In this article, the problem of laminar, isothermal, incompressible and viscous flow in a rectangular domain bounded by two moving porous walls, which enable the fluid to enter or exit during successive expansions or contractions, is investigated. The governing non-linear equations and their associated boundary conditions are transformed into a highly non-linear ordinary differential equation. The series solution of the problem is obtained by utilising the homotopy perturbation method. Graphical results are presented to investigate the influence of the non-dimensional wall dilation rate and seepage Reynolds number (Re) on the velocity, normal pressure distribution and wall shear stress. Since the transport of biological fluids through contracting or expanding vessels is characterised by low seepage Res, the current study focuses on the viscous flow driven by small wall contractions and expansions of two weakly permeable walls.

  10. Connected block and effective conductivity (CONBEC) computer program to predict heat flow through multicomponent refractory lined gasifier vessel walls. Users manual

    SciTech Connect

    Whitacre, G.R.; Grinberg, I.M.

    1980-01-01

    CONBEC is a computer programmed model which determines the steady-state heat flow through multicomponent refractory-lined gasifier vessel walls. The model accounts for the effects of lining thickness, porosity, gaps, cracks, refractory composition, physical form, anchor spacing and configuration, gas pressure and composition, and other parameters on heat flow. CONBEC is based on a combination of the CONnected Block and Effective Conductivity techniques. The refractory wall is described as a series of blocks, each with its own effective thermal conductivity. The connected blocks are used to handle nonlinear temperature effects, material difference, and location effects. Parallel heat flow paths through the wall are used to provide for distinct material changes, gaps, conductivity changes, and hot-spot determination. The typical configuration has two parallel heat flow paths. Anchors can be treated as a separate heat flow path or can be left out. The blocks are cross-linked to account for lateral heat flow between the parallel paths. The model is extremely simple to use yet it provides considerable information regarding the importance of material, design, and operational parameters on heat flow in refractory vessel walls and on hot spots. It was developed to be used in the design of material systems for coal gasification vessels and has broad applicability to other refractory linings for furnaces or process vessels.The output results of CONBEC are in good agreement with experimental data obtained for several refractory material systems over a range of wall temperatures, gas compositions, wall thicknesses, crack and gap characteristics, and gas pressures.

  11. Compliant model of a coupled sequential coronary arterial bypass graft: effects of vessel wall elasticity and non-Newtonian rheology on blood flow regime and hemodynamic parameters distribution.

    PubMed

    Kabinejadian, Foad; Ghista, Dhanjoo N

    2012-09-01

    We have recently developed a novel design for coronary arterial bypass surgical grafting, consisting of coupled sequential side-to-side and end-to-side anastomoses. This design has been shown to have beneficial blood flow patterns and wall shear stress distributions which may improve the patency of the CABG, as compared to the conventional end-to-side anastomosis. In our preliminary computational simulation of blood flow of this coupled sequential anastomoses design, the graft and the artery were adopted to be rigid vessels and the blood was assumed to be a Newtonian fluid. Therefore, the present study has been carried out in order to (i) investigate the effects of wall compliance and non-Newtonian rheology on the local flow field and hemodynamic parameters distribution, and (ii) verify the advantages of the CABG coupled sequential anastomoses design over the conventional end-to-side configuration in a more realistic bio-mechanical condition. For this purpose, a two-way fluid-structure interaction analysis has been carried out. A finite volume method is applied to solve the three-dimensional, time-dependent, laminar flow of the incompressible, non-Newtonian fluid; the vessel wall is modeled as a linearly elastic, geometrically non-linear shell structure. In an iteratively coupled approach the transient shell equations and the governing fluid equations are solved numerically. The simulation results indicate a diameter variation ratio of up to 4% and 5% in the graft and the coronary artery, respectively. The velocity patterns and qualitative distribution of wall shear stress parameters in the distensible model do not change significantly compared to the rigid-wall model, despite quite large side-wall deformations in the anastomotic regions. However, less flow separation and reversed flow is observed in the distensible models. The wall compliance reduces the time-averaged wall shear stress up to 32% (on the heel of the conventional end-to-side model) and somewhat

  12. The fluid dynamic and shear environment in the NASA/JSC rotating-wall perfused-vessel bioreactor

    NASA Technical Reports Server (NTRS)

    Begley, C. M.; Kleis, S. J.

    2000-01-01

    The rotating-wall perfused-vessel (RWPV) bioreactor, used for both microgravity and Earth-based cell science experiments, is characterized in terms of the fluid dynamic and fluid shear stress environment. A numerical model of the flow field is developed and verified with laser Doppler velocimeter measurements. The effects of changes in operating conditions, including rotation rates and fluid perfusion rates, are investigated with the numerical model. The operating conditions typically used for ground-based experiments (equal rotation of the inner and outer cylinders) leads to flow patterns with relatively poor mass distribution characteristics. Approximately 50% of the inlet-perfused fluid bypasses the bulk of the fluid volume and flows to the perfusion exit. For operating conditions typical in microgravity, small differential rotation rates between the inner and outer cylinders lead to greatly improved flow distribution patterns and very low fluid shear stress levels over a large percentage of the fluid volume. Differences in flow patterns for the different operating conditions are explored. Large differences in the hydrodynamic environments for operating conditions typical of true microgravity and ground-based "microgravity simulations" are demonstrated.

  13. Morphologic differentiation of colon carcinoma cell lines HT-29 and HT-29KM in rotating-wall vessels

    NASA Technical Reports Server (NTRS)

    Goodwin, T. J.; Jessup, J. M.; Wolf, D. A.

    1992-01-01

    A new low shear stress microcarrier culture system has been developed at NASA's Johnson Space Center that permits three-dimensional tissue culture. Two established human colon adenocarcinoma cell lines, HT-29, an undifferentiated, and HT-29KM, a stable, moderately differentiated subline of HT-29, were grown in new tissue culture bioreactors called Rotating-Wall Vessels (RWVs). RWVs are used in conjunction with multicellular cocultivation to develop a unique in vitro tissue modeling system. Cells were cultivated on Cytodex-3 microcarrier beads, with and without mixed normal human colonic fibroblasts, which served as the mesenchymal layer. Culture of the tumor lines in the absence of fibroblasts produced spheroidlike growth and minimal differentiation. In contrast, when tumor lines were co-cultivated with normal colonic fibroblasts, initial growth was confined to the fibroblast population until the microcarriers were covered. The tumor cells then commenced proliferation at an accelerated rate, organizing themselves into three-dimensional tissue masses that achieved 1.0- to 1.5-cm diameters. The masses displayed glandular structures, apical and internal glandular microvilli, tight intercellular junctions, desmosomes, cellular polarity, sinusoid development, internalized mucin, and structural organization akin to normal colon crypt development. Differentiated samples were subjected to transmission and scanning electron microscopy and histologic analysis, revealing embryoniclike mesenchymal cells lining the areas around the growth matrices. Necrosis was minimal throughout the tissue masses. These data suggest that the RWV affords a new model for investigation and isolation of growth, regulatory, and structural processes within neoplastic and normal tissue.

  14. The fluid dynamic and shear environment in the NASA/JSC rotating-wall perfused-vessel bioreactor

    NASA Technical Reports Server (NTRS)

    Begley, C. M.; Kleis, S. J.

    2000-01-01

    The rotating-wall perfused-vessel (RWPV) bioreactor, used for both microgravity and Earth-based cell science experiments, is characterized in terms of the fluid dynamic and fluid shear stress environment. A numerical model of the flow field is developed and verified with laser Doppler velocimeter measurements. The effects of changes in operating conditions, including rotation rates and fluid perfusion rates, are investigated with the numerical model. The operating conditions typically used for ground-based experiments (equal rotation of the inner and outer cylinders) leads to flow patterns with relatively poor mass distribution characteristics. Approximately 50% of the inlet-perfused fluid bypasses the bulk of the fluid volume and flows to the perfusion exit. For operating conditions typical in microgravity, small differential rotation rates between the inner and outer cylinders lead to greatly improved flow distribution patterns and very low fluid shear stress levels over a large percentage of the fluid volume. Differences in flow patterns for the different operating conditions are explored. Large differences in the hydrodynamic environments for operating conditions typical of true microgravity and ground-based "microgravity simulations" are demonstrated.

  15. Morphologic differentiation of colon carcinoma cell lines HT-29 and HT-29KM in rotating-wall vessels

    NASA Technical Reports Server (NTRS)

    Goodwin, T. J.; Jessup, J. M.; Wolf, D. A.

    1992-01-01

    A new low shear stress microcarrier culture system has been developed at NASA's Johnson Space Center that permits three-dimensional tissue culture. Two established human colon adenocarcinoma cell lines, HT-29, an undifferentiated, and HT-29KM, a stable, moderately differentiated subline of HT-29, were grown in new tissue culture bioreactors called Rotating-Wall Vessels (RWVs). RWVs are used in conjunction with multicellular cocultivation to develop a unique in vitro tissue modeling system. Cells were cultivated on Cytodex-3 microcarrier beads, with and without mixed normal human colonic fibroblasts, which served as the mesenchymal layer. Culture of the tumor lines in the absence of fibroblasts produced spheroidlike growth and minimal differentiation. In contrast, when tumor lines were co-cultivated with normal colonic fibroblasts, initial growth was confined to the fibroblast population until the microcarriers were covered. The tumor cells then commenced proliferation at an accelerated rate, organizing themselves into three-dimensional tissue masses that achieved 1.0- to 1.5-cm diameters. The masses displayed glandular structures, apical and internal glandular microvilli, tight intercellular junctions, desmosomes, cellular polarity, sinusoid development, internalized mucin, and structural organization akin to normal colon crypt development. Differentiated samples were subjected to transmission and scanning electron microscopy and histologic analysis, revealing embryoniclike mesenchymal cells lining the areas around the growth matrices. Necrosis was minimal throughout the tissue masses. These data suggest that the RWV affords a new model for investigation and isolation of growth, regulatory, and structural processes within neoplastic and normal tissue.

  16. Disturbed flow promotes deposition of leucocytes from flowing whole blood in a model of a damaged vessel wall.

    PubMed

    Skilbeck, Christopher A; Walker, Peter G; David, Tim; Nash, Gerard B

    2004-08-01

    Departure from simple laminar flow in arteries may promote the local attachment of leucocytes either to intact endothelium or platelet thrombi. We perfused blood through a chamber with a backward facing step, to observe whether adhesion from whole blood to P-selectin was indeed localized to a region of recirculating flow, and whether platelets binding to collagen in such a region could capture leucocytes. Blood flowing over the step established a stable vortex, a reattachment point where forward and backward flow separated, and a simple laminar flow with wall shear rate c. 400/s further downstream. Fluorescently labelled leucocytes were observed to attach to P-selectin immediately upstream or downstream of the reattachment point, and to roll back towards the step or away from it, respectively. There was negligible adhesion further downstream. When a P-selectin-Fc chimaera was used to coat the chamber, stable attachment occurred, again preferentially in the disturbed flow region. Numerous platelets adhered to a collagen coating throughout the chamber, although there were local maxima either side of the reattachment point. The adherent platelets captured flowing leucocytes in these regions alone. Leucocytes may adhere from flowing blood in vessels with high shear rate if the flow is disturbed. While platelets can adhere over a wider range of shear rates, their ability to capture leucocytes may be restricted to regions of disturbed flow. Copyright 2004 Blackwell Publishing Ltd

  17. T2‐Weighted intracranial vessel wall imaging at 7 Tesla using a DANTE‐prepared variable flip angle turbo spin echo readout (DANTE‐SPACE)

    PubMed Central

    Viessmann, Olivia; Li, Linqing; Benjamin, Philip

    2016-01-01

    Purpose To optimize intracranial vessel wall imaging (VWI) at 7T for sharp wall depiction and high boundary contrast. Methods A variable flip angle turbo spin echo scheme (SPACE) was optimized for VWI. SPACE provides black‐blood contrast, but has less crushing effect on cerebrospinal fluid (CSF). However, a delay alternating with nutation for tailored excitation (DANTE) preparation suppresses the signal from slowly moving spins of a few mm per second. Therefore, we optimized a DANTE‐preparation module for 7T. Signal‐to‐noise ratio (SNR), contrast‐to‐noise ratio (CNR), and signal ratio for vessel wall, CSF, and lumen were calculated for SPACE and DANTE‐SPACE in 11 volunteers at the middle cerebral artery (MCA). An exemplar MCA stenosis patient was scanned with DANTE‐SPACE. Results The 7T‐optimized SPACE sequence improved the vessel wall point‐spread function by 17%. The CNR between the wall and CSF was doubled (12.2 versus 5.6) for the DANTE‐SPACE scans compared with the unprepared SPACE. This increase was significant in the right hemisphere (P = 0.016), but not in the left (P = 0.090). The CNR between wall and lumen was halved, but remained at a high value (24.9 versus 56.5). Conclusion The optimized SPACE sequence improves VWI at 7T. Additional DANTE preparation increases the contrast between the wall and CSF. Increased outer boundary contrast comes at the cost of reduced inner boundary contrast. Magn Reson Med 77:655–663, 2017. © 2016 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. PMID:26890988

  18. Assessment of myocardial segmental function with coronary artery stenosis in multi-vessel coronary disease patients with normal wall motion.

    PubMed

    Xie, M-Y; Lv, Q; Wang, J; Yin, J-B

    2016-04-01

    To discover the impact of the various degrees of coronary artery stenosis (CAD) on the left ventricular systolic dysfunction in steady state with quantitative analysis of the regional systolic myocardium in longitudinal, radial and circumferential direction in patients with coronary artery disease by two-dimensional speckle tracking imaging (STI). Forty-three normal wall motion-multi vessel coronary artery disease (NWM-MVD) patients labeled as the experimental groups and forty-two subjects with little risk of CAD marked as the control group were enrolled in this study. The two-dimensional STI was obtained in the apical long axis and three levels of the short axis of the left ventricle. The left ventricular wall was divided into 18 segments. The affected myocardia were divided into three groups: group B (coronary stenosis degree ≤50%), group C (coronary stenosis degree 50%-99%)and group D (coronary stenosis degree ≥99%). Using the Q-analysis software, the longitudinal, radial and circumferential systolic strain (SL, SR, SC) and strain ratio (SrL, SrR, SrC) of the myocardium were analyzed. The bradycardia in the NWM-MVD group is greater than that in the control group (16/43 vs. 7/42, p <0.05). Compared with the control group, the SL and SR of group B, group C and group D decreased significantly (p <0.05). Compared with group C, the SL of group D also decreased significantly (p <0.05). However, there was no SC difference among the four groups. Meanwhile, compared with group A, the SrL, SrR and SrC of group B, group C and group D decreased significantly (p <0.05). Compared with group A, group B and group C, the SrL and SrC of group D also decreased (p <0.05). Compared with group A and group C, the SrR of group D decreased. The SrL was equal to 1.085 for the cut-off value, and the sum (1.348) of sensitivity (0.673) and specificity (0.675) were the greatest. Bland-Altman analysis showed that there was myocardium conformity of in both the multi-vessel CAD patients and

  19. Vascular tissue-specific gene expression of xylem sap glycine-rich proteins in root and their localization in the walls of metaxylem vessels in cucumber.

    PubMed

    Sakuta, C; Satoh, S

    2000-05-01

    Root-specific cDNAs of glycine-rich protein (cucumber root glycine rich protein-1 and -2; CRGRP-1 and CRGRP-2) were cloned previously by use of an antiserum raised against whole xylem sap of Cucumis sativus. The accumulation of the corresponding mRNA at high levels was detected in the root-hair zone of cucumber tap root [Sakuta et al. (1998) Plant Cell Physiol. 39: 1330]. The RNA gel blot analysis with the CRGRP-1- and -2-specific probes revealed that the CRGRP genes expressed only in root but not at all in aboveground organs. When the localization of these mRNAs were examined by in situ hybridization, CRGRP mRNAs were found only in the parenchyma cells in the central cylinder of young lateral roots and it was most abundant in the cells that surrounded xylem vessels in the root-hair zone of the tap root. In immunoblotting of xylem sap collected from cucumber stem with an antiserum raised against CRGRP-1 that had been produced in an E. coli expression system, the antibodies, which did not cross-react with GRP1.8 of kidney bean, reacted with two proteins, whose mobilities corresponded to those of proteins deduced from the CRGRP-1 and -2 cDNAs. Immunohistochemical staining revealed that the CRGRPs accumulated specifically in the lignified walls of metaxylem vessels in the root, stem and leaf and in the lignified cell walls of perivascular fibers in cucumber stems. Immunostaining was also detected in the walls of metaxylem vessels and in the cell walls of adjacent sclerenchyma in the hypocotyl of kidney bean. These data clearly indicate that the novel glycine-rich proteins were produced in the vascular tissue of the root, transported systemically over a long distance via the xylem sap and immobilized in the walls of metaxylem vessels and sclerechyma cells in aboveground organs.

  20. Long Term Follow-Up of the Endovascular Trans-Vessel Wall Technique for Parenchymal Access in Rabbit with Full Clinical Integration

    PubMed Central

    Lundberg, Johan; Jonsson, Stefan; Holmin, Staffan

    2011-01-01

    Objective Endovascular techniques are providing options to surgical/percutaneous cell transplantation methods. Some cells, e.g. insulin producing cells, are not suitable for intra-luminal transplantation and for such cells, other options must be found. We have constructed a “nanocatheter” with a penetrating tip for vessel perforation, thereby creating a working channel for parenchymal access by endovascular technique. To finish the procedure safely, the distal tip is detached to provide a securing plug in the vessel wall defect. Materials and Methods We have performed interventions with full clinical integration in the superior mesenteric artery (SMA), the subclavian artery and the external carotid artery in rabbits. No hemorrhagic- or thromboembolic events occurred during the procedure. Stenosis formation and distal embolisation were analyzed by angiography and macroscopic inspection during autopsy at five, 30 and 80 days. All animals and implanted devices were also evaluated by micro-dissections and histochemical analysis. Results In this study we show safety data on the trans-vessel wall technique by behavioral, angiographical and histological analysis. No stenosis formation was observed at any of the follow-up time points. No animals or organs have shown any signs of distress due to the intervention. Histological examination showed no signs of hemorrhage, excellent biocompatibility with no inflammation and a very limited fibrous capsule formation around the device, comparable to titanium implants. Further, no histological changes were detected in the endothelia of the vessels subject to intervention. Conclusions The trans-vessel wall technique can be applied for e.g. cell transplantations, local substance administration and tissue sampling with low risk for complications during the procedure and low risk for hemorrhage, stenosis development or adverse tissue reactions with an 80 days follow-up time. The benefit should be greatest in organs that are

  1. Bioreactor rotating wall vessel

    NASA Technical Reports Server (NTRS)

    2001-01-01

    The NASA Bioreactor provides a low turbulence culture environment which promotes the formation of large, three-dimensional cell clusters. Due to their high level of cellular organization and specialization, samples constructed in the bioreactor more closely resemble the original tumor or tissue found in the body. The work is sponsored by NASA's Office of Biological and Physical Research. The bioreactor is managed by the Biotechnology Cell Science Program at NASA's Johnson Space Center (JSC). NASA-sponsored bioreactor research has been instrumental in helping scientists to better understand normal and cancerous tissue development. In cooperation with the medical community, the bioreactor design is being used to prepare better models of human colon, prostate, breast and ovarian tumors. Cartilage, bone marrow, heart muscle, skeletal muscle, pancreatic islet cells, liver and kidney are just a few of the normal tissues being cultured in rotating bioreactors by investigators. Cell constructs grown in a rotating bioreactor on Earth (left) eventually become too large to stay suspended in the nutrient media. In the microgravity of orbit, the cells stay suspended. Rotation then is needed for gentle stirring to replenish the media around the cells.

  2. Bioreactor rotating wall vessel

    NASA Technical Reports Server (NTRS)

    2001-01-01

    The NASA Bioreactor provides a low turbulence culture environment which promotes the formation of large, three-dimensional cell clusters. Due to their high level of cellular organization and specialization, samples constructed in the bioreactor more closely resemble the original tumor or tissue found in the body. The work is sponsored by NASA's Office of Biological and Physical Research. The bioreactor is managed by the Biotechnology Cell Science Program at NASA's Johnson Space Center (JSC). NASA-sponsored bioreactor research has been instrumental in helping scientists to better understand normal and cancerous tissue development. In cooperation with the medical community, the bioreactor design is being used to prepare better models of human colon, prostate, breast and ovarian tumors. Cartilage, bone marrow, heart muscle, skeletal muscle, pancreatic islet cells, liver and kidney are just a few of the normal tissues being cultured in rotating bioreactors by investigators. Cell constructs grown in a rotating bioreactor on Earth (left) eventually become too large to stay suspended in the nutrient media. In the microgravity of orbit, the cells stay suspended. Rotation then is needed for gentle stirring to replenish the media around the cells.

  3. Utility of birefringence changes due to collagen thermal denaturation rate process analysis: vessel wall temperature estimation for new short term heating balloon angioplasty

    NASA Astrophysics Data System (ADS)

    Kaneko, Kenji; Shimazaki, Natsumi; Gotoh, Maya; Nakatani, Eriko; Arai, Tsunenori

    2007-02-01

    Our photo thermal reaction heating architecture balloon realizes less than 10 s short term heating that can soften vessel wall collagen without damaging surrounding tissue thermally. New thermal balloon angioplasty, photo-thermo dynamic balloon angioplasty (PTDBA) has experimentally shown sufficient opening with 2 atm low pressure dilation and prevention of chronic phase restenosis and acute phase thrombus in vivo. Even though PTDBA has high therapeutic potential, the most efficient heating condition is still under study, because relationship of treatment and thermal dose to vessel wall is not clarified yet. To study and set the most efficient heating condition, we have been working on establishment of temperature history estimation method from our previous experimental results. Heating target of PTDBA, collagen, thermally denatures following rate process. Denaturation is able to be quantified with measured collagen birefringence value. To express the denaturation with equation of rate process, the following ex vivo experiments were performed. Porcine extracted carotid artery was soaked in two different temperature saline baths to enforce constant temperature heating. Higher temperature bath was set to 40 to 80 degree Celsius and soaking duration was 5 to 40 s. Samples were observed by a polarizing microscope and a scanning electron microscope. The birefringence was measured by polarizing microscopic system using Brace-Koehler compensator 1/30 wavelength. The measured birefringence showed temperature dependency and quite fit with the rate process equation. We think vessel wall temperature is able to be estimated using the birefringence changes due to thermal denaturation.

  4. Topical hexylaminolevulinate and aminolevulinic acid photodynamic therapy: complete arteriole vasoconstriction occurs frequently and depends on protoporphyrin IX concentration in vessel wall.

    PubMed

    Middelburg, T A; de Bruijn, H S; Tettero, L; van der Ploeg van den Heuvel, A; Neumann, H A M; de Haas, E R M; Robinson, D J

    2013-09-05

    Vascular responses to photodynamic therapy (PDT) may influence the availability of oxygen during PDT and the extent of tumor destruction after PDT. However, for topical PDT vascular effects are largely unknown. Arteriole and venule diameters were measured before and after hexylaminolevulinate (HAL) and aminolevulinic acid (ALA) PDT and related to the protoporphyrin IX (PpIX) concentration in the vessel wall. A mouse skin fold chamber model and an intravital confocal microscope allowed direct imaging of the subcutaneous vessels underlying the treated area. In both HAL and ALA groups over 60% of arterioles constricted completely, while venules generally did not respond, except for two larger veins that constricted partially. Arteriole vasoconstriction strongly correlated with PpIX fluorescence intensity in the arteriole wall. Total PpIX fluorescence intensity was significantly higher for HAL than ALA for the whole area that was imaged but not for the arteriole walls. In conclusion, complete arteriole vasoconstriction occurs frequently in both HAL and ALA based topical PDT, especially when relatively high PpIX concentrations in arteriole walls are reached. Vasoconstriction will likely influence PDT effect and should be considered in studies on topical HAL and ALA-PDT. Also, our results may redefine the vasculature as a potential secondary target for topical PDT. Copyright © 2013 Elsevier B.V. All rights reserved.

  5. Nutritional supplementation with L-arginine prevents pelvic radiation-induced changes in morphology, density, and regulating factors of blood vessels in the wall of rat bladder.

    PubMed

    Costa, Waldemar S; Ribeiro, Monica N; Cardoso, Luiz E M; Dornas, Maria C; Ramos, Cristiane F; Gallo, Carla B M; Sampaio, Francisco J B

    2013-06-01

    To determine whether L-arginine has protective effects against radiation-induced alterations in the morphology and regulatory factors of vesical blood vessels in rats. Male rats aged 3-4 months were divided into groups of 10 animals each: (a) controls, consisting of non-treated animals; (b) radiated-only rats; and (c) radiated rats receiving L-arginine supplementation. Radiation was in one session of 10 Gy and was aimed at the pelvic-abdominal region. L-arginine was administered once a day (0.65 g/kg body weight), starting 7 days before radiation and continuing until killing on the 16th day after radiation. The density, relative area, and wall thickness of blood vessels were measured in the vesical lamina propria using histological methods, and the expression of vascular endothelial growth factor (VEGF) and fibroblast growth factors (FGF) in the bladder wall was assessed by RT-PCR. Compared with controls, radiation alone decreased the density and relative area of blood vessels by 32 % (p < 0.01) and 25 % (p < 0.05), respectively, and reduced the arterial wall thickness by 42 % (p < 0.004). VEGF and FGF mRNA levels after radiation were diminished by 67 % (p < 0.002) and 56 % (p < 0.04), respectively. The radiated animals supplemented with L-arginine were not significantly different from controls. Pelvic radiation leads to significant vesical modifications, as in the morphology of blood vessels and in VEGF and FGF expression. All these changes, however, were prevented by L-arginine treatment. These results emphasize, therefore, the potential use of this amino acid as a radioprotective drug.

  6. Hair follicle-derived blood vessels vascularize tumors in skin and are inhibited by Doxorubicin.

    PubMed

    Amoh, Yasuyuki; Li, Lingna; Yang, Meng; Jiang, Ping; Moossa, Abdool R; Katsuoka, Kensei; Hoffman, Robert M

    2005-03-15

    We have recently shown that the neural-stem cell marker nestin is expressed in hair follicle stem cells and the blood vessel network interconnecting hair follicles in the skin of transgenic mice with nestin regulatory element-driven green fluorescent protein (ND-GFP). The hair follicles were shown to give rise to the nestin-expressing blood vessels in the skin. In the present study, we visualized tumor angiogenesis by dual-color fluorescence imaging in ND-GFP transgenic mice after transplantation of the murine melanoma cell line B16F10 expressing red fluorescent protein. ND-GFP was highly expressed in proliferating endothelial cells and nascent blood vessels in the growing tumor. Results of immunohistochemical staining showed that the blood vessel-specific antigen CD31 was expressed in ND-GFP-expressing nascent blood vessels. ND-GFP expression was diminished in the vessels with increased blood flow. Progressive angiogenesis during tumor growth was readily visualized during tumor growth by GFP expression. Doxorubicin inhibited the nascent tumor angiogenesis as well as tumor growth in the ND-GFP mice transplanted with B16F10-RFP. This model is useful for direct visualization of tumor angiogenesis and evaluation of angiogenic inhibitors.

  7. T2-Weighted intracranial vessel wall imaging at 7 Tesla using a DANTE-prepared variable flip angle turbo spin echo readout (DANTE-SPACE).

    PubMed

    Viessmann, Olivia; Li, Linqing; Benjamin, Philip; Jezzard, Peter

    2017-02-01

    To optimize intracranial vessel wall imaging (VWI) at 7T for sharp wall depiction and high boundary contrast. A variable flip angle turbo spin echo scheme (SPACE) was optimized for VWI. SPACE provides black-blood contrast, but has less crushing effect on cerebrospinal fluid (CSF). However, a delay alternating with nutation for tailored excitation (DANTE) preparation suppresses the signal from slowly moving spins of a few mm per second. Therefore, we optimized a DANTE-preparation module for 7T. Signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and signal ratio for vessel wall, CSF, and lumen were calculated for SPACE and DANTE-SPACE in 11 volunteers at the middle cerebral artery (MCA). An exemplar MCA stenosis patient was scanned with DANTE-SPACE. The 7T-optimized SPACE sequence improved the vessel wall point-spread function by 17%. The CNR between the wall and CSF was doubled (12.2 versus 5.6) for the DANTE-SPACE scans compared with the unprepared SPACE. This increase was significant in the right hemisphere (P = 0.016), but not in the left (P = 0.090). The CNR between wall and lumen was halved, but remained at a high value (24.9 versus 56.5). The optimized SPACE sequence improves VWI at 7T. Additional DANTE preparation increases the contrast between the wall and CSF. Increased outer boundary contrast comes at the cost of reduced inner boundary contrast. Magn Reson Med 77:655-663, 2017. © 2016 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. © 2016 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine.

  8. A Tissue Engineered Blood Vessel Model of Hutchinson-Gilford Progeria Syndrome Using Human iPSC-derived Smooth Muscle Cells.

    PubMed

    Atchison, Leigh; Zhang, Haoyue; Cao, Kan; Truskey, George A

    2017-08-15

    Hutchison-Gilford Progeria Syndrome (HGPS) is a rare, accelerated aging disorder caused by nuclear accumulation of progerin, an altered form of the Lamin A gene. The primary cause of death is cardiovascular disease at about 14 years. Loss and dysfunction of smooth muscle cells (SMCs) in the vasculature may cause defects associated with HGPS. Due to limitations of 2D cell culture and mouse models, there is a need to develop improved models to discover novel therapeutics. To address this need, we produced a functional three-dimensional model of HGPS that replicates an arteriole-scale tissue engineered blood vessel (TEBV) using induced pluripotent stem cell (iPSC)-derived SMCs from an HGPS patient. To isolate the effect of the HGPS iSMCs, the endothelial layer consisted of human cord blood-derived endothelial progenitor cells (hCB-EPCs) from a separate, healthy donor. TEBVs fabricated from HGPS iSMCs and hCB-EPCs show reduced vasoactivity, increased medial wall thickness, increased calcification and apoptosis relative to TEBVs fabricated from normal iSMCs or primary MSCs. Additionally, treatment of HGPS TEBVs with the proposed therapeutic Everolimus, increases HGPS TEBV vasoactivity and increases iSMC differentiation in the TEBVs. These results show the ability of this iPSC-derived TEBV to reproduce key features of HGPS and respond to drugs.

  9. Dilated Thin-Walled Blood and Lymphatic Vessels in Human Endometrium: A Potential Role for VEGF-D in Progestin-Induced Break-Through Bleeding

    PubMed Central

    Donoghue, Jacqueline F.; McGavigan, C. Jay; Lederman, Fiona L.; Cann, Leonie M.; Fu, Lulu; Dimitriadis, Eva; Girling, Jane E.; Rogers, Peter A. W.

    2012-01-01

    Progestins provide safe, effective and cheap options for contraception as well as the treatment of a variety of gynaecological disorders. Episodes of irregular endometrial bleeding or breakthrough bleeding (BTB) are a major unwanted side effect of progestin treatment, such that BTB is the leading cause for discontinued use of an otherwise effective and popular medication. The cellular mechanisms leading to BTB are poorly understood. In this study, we make the novel finding that the large, dilated, thin walled vessels characteristic of human progestin-treated endometrium include both blood and lymphatic vessels. Increased blood and lymphatic vessel diameter are features of VEGF-D action in other tissues and we show by immunolocalisation and Western blotting that stromal cell decidualisation results in a significant increase in VEGF-D protein production, particularly of the proteolytically processed 21 kD form. Using a NOD/scid mouse model with xenografted human endometrium we were able to show that progestin treatment causes decidualisation, VEGF-D production and endometrial vessel dilation. Our results lead to a novel hypothesis to explain BTB, with stromal cell decidualisation rather than progestin treatment per se being the proposed causative event, and VEGF-D being the proposed effector agent. PMID:22383980

  10. VEGF treatment promotes bone marrow-derived CXCR4+ mesenchymal stromal stem cell differentiation into vessel endothelial cells

    PubMed Central

    Li, Qiming; Xia, Shudong; Fang, Hanyun; Pan, Jiansheng; Jia, Yinfeng; Deng, Gang

    2017-01-01

    Stem/progenitor cells serve an important role in the process of blood vessel repair. However, the mechanism of vascular repair mediated by C-X-C chemokine receptor type 4-positive (CXCR4+) bone marrow-derived mesenchymal stem cells (BMSCs) following myocardial infarction remains unclear. The aim of the present study was to investigate the effects of vascular endothelial growth factor (VEGF) on vessel endothelial differentiation from BMSCs. CXCR4+ BMSCs were isolated from the femoral bone marrow of 2-month-old mice and the cells were treated with VEGF. Expression of endothelial cell markers and the functional properties were assessed by reverse transcription-quantitative polymerase chain reaction, flow cytometry and vascular formation analyses. The results indicated that the CXCR4+ BMSCs from femoral bone marrow cells expressed putative cell surface markers of mesenchymal stem cells. Treatment with VEGF induced platelet/endothelial cell adhesion molecule-1 (PECAM-1) and von Willebrand factor (vWF) expression at the transcriptional and translational levels, compared with untreated controls. Moreover, VEGF treatment induced CXCR4+ BMSCs to form hollow tube-like structures on Matrigel, suggesting that the differentiated endothelial cells had the functional properties of blood vessels. The results demonstrate that the CXCR4+ BMSCs were able to differentiate into vessel endothelial cells following VEGF treatment. For cell transplantation in vascular disease, it may be concluded that CXCR4+ BMSCs are a novel source of endothelial progenitor cells with high potential for application in vascular repair. PMID:28352314

  11. Detectability of small blood vessels with high-frequency power Doppler and selection of wall filter cut-off velocity for microvascular imaging.

    PubMed

    Pinter, Stephen Z; Lacefield, James C

    2009-07-01

    Power Doppler imaging of physiologic and pathologic angiogenesis is widely used in preclinical studies to track normal development, disease progression and treatment efficacy but can be challenging given the presence of small blood vessels and slow flow velocities. Power Doppler images can be plagued with false-positive color pixels or undetected vessels, thereby complicating the interpretation of vascularity metrics such as color pixel density (CPD). As an initial step toward improved microvascular quantification, flow-phantom experiments were performed to establish relationships between vessel detection and various combinations of vessel size (160, 200, 250, 300 and 360 microm), flow velocity (4, 3, 2, 1 and 0.5 mm/s) and transducer frequency (30 and 40 MHz) while varying the wall filter cut-off velocity. Receiver operating characteristic (ROC) curves and areas under ROC curves indicate that good vessel detection performance can be achieved with a 40-MHz transducer for flow velocities > or =2 mm/s and with a 30-MHz transducer for flow velocities > or =1 mm/s. In the second part of the analysis, CPD was plotted as a function of wall filter cut-off velocity for each flow-phantom data set. Three distinct regions were observed: overestimation of CPD at low cut-offs, underestimation of CPD at high cut-offs and a plateau at intermediate cut-offs. The CPD at the plateau closely matched the phantom's vascular volume fraction and the length of the plateau corresponded with the flow-detection performance of the Doppler system assessed using ROC analysis. Color pixel density vs. wall filter cut-off curves from analogous in vivo experiments exhibited the same shape, including a distinct CPD plateau. The similar shape of the flow-phantom and in vivo curves suggests that the presence of a plateau in vivo can be used to identify the best-estimate CPD value that can be treated as a quantitative vascularity metric. The ability to identify the best CPD estimate is expected to

  12. Comparative survival study of glial cells and cells composing walls of blood vessels in crustacean ventral nerve cord after photodynamic treatment

    NASA Astrophysics Data System (ADS)

    Kolosov, Mikhail S.; Shubina, Elena

    2015-03-01

    Photodynamic therapy is a prospective treatment modality of brain cancers. It is of importance to have information about relative survival rate of different cell types in nerve tissue during photodynamic treatment. Particularly, for development of sparing strategy of the photodynamic therapy of brain tumors, which pursuits both total elimination of malignant cells, which are usually of glial origin, and, at the same time, preservation of normal blood circulation as well as normal glial cells in the brain. The aim of this work was to carry out comparative survival study of glial cells and cells composing walls of blood vessels after photodynamic treatment, using simple model object - ventral nerve cord of crustacean.

  13. Venous-derived angioblasts generate organ-specific vessels during zebrafish embryonic development

    PubMed Central

    Hen, Gideon; Nicenboim, Julian; Mayseless, Oded; Asaf, Lihee; Shin, Masahiro; Busolin, Giorgia; Hofi, Roy; Almog, Gabriella; Tiso, Natascia; Lawson, Nathan D.; Yaniv, Karina

    2015-01-01

    Formation and remodeling of vascular beds are complex processes orchestrated by multiple signaling pathways. Although it is well accepted that vessels of a particular organ display specific features that enable them to fulfill distinct functions, the embryonic origins of tissue-specific vessels and the molecular mechanisms regulating their formation are poorly understood. The subintestinal plexus of the zebrafish embryo comprises vessels that vascularize the gut, liver and pancreas and, as such, represents an ideal model in which to investigate the early steps of organ-specific vessel formation. Here, we show that both arterial and venous components of the subintestinal plexus originate from a pool of specialized angioblasts residing in the floor of the posterior cardinal vein (PCV). Using live imaging of zebrafish embryos, in combination with photoconvertable transgenic reporters, we demonstrate that these angioblasts undergo two phases of migration and differentiation. Initially, a subintestinal vein forms and expands ventrally through a Bone Morphogenetic Protein-dependent step of collective migration. Concomitantly, a Vascular Endothelial Growth Factor-dependent shift in the directionality of migration, coupled to the upregulation of arterial markers, is observed, which culminates with the generation of the supraintestinal artery. Together, our results establish the zebrafish subintestinal plexus as an advantageous model for the study of organ-specific vessel development and provide new insights into the molecular mechanisms controlling its formation. More broadly, our findings suggest that PCV-specialized angioblasts contribute not only to the formation of the early trunk vasculature, but also to the establishment of late-forming, tissue-specific vascular beds. PMID:26525671

  14. Dual shell pressure balanced vessel

    DOEpatents

    Fassbender, Alexander G.

    1992-01-01

    A dual-wall pressure balanced vessel for processing high viscosity slurries at high temperatures and pressures having an outer pressure vessel and an inner vessel with an annular space between the vessels pressurized at a pressure slightly less than or equivalent to the pressure within the inner vessel.

  15. High-resolution 3D coronary vessel wall imaging with near 100% respiratory efficiency using epicardial fat tracking: reproducibility and comparison with standard methods.

    PubMed

    Scott, Andrew D; Keegan, Jennifer; Firmin, David N

    2011-01-01

    To quantitatively assess the performance and reproducibility of 3D spiral coronary artery wall imaging with beat-to-beat respiratory-motion-correction (B2B-RMC) compared to navigator gated 2D spiral and turbo-spin-echo (TSE) acquisitions. High-resolution (0.7 × 0.7 mm) cross-sectional right coronary wall acquisitions were performed in 10 subjects using four techniques (B2B-RMC 3D spiral with alternate (2RR) and single (1RR) R-wave gating, navigator-gated 2D spiral (2RR) and navigator-gated 2D TSE (2RR)) on two occasions. Wall thickness measurements were compared with repeated measures analysis of variance (ANOVA). Reproducibility was assessed with the intraclass correlation coefficient (ICC). In all, 91% (73/80) of acquisitions were successful (failures: four TSE, two 3D spiral (1RR) and one 3D spiral (2RR)). Respiratory efficiency of the B2B-RMC was less variable and substantially higher than for navigator gating (99.6 ± 1.2% vs. 39.0 ± 7.5%, P < 0.0001). Coronary wall thicknesses (± standard deviation [SD]) were not significantly different: 1.10 ± 0.14 mm (3D spiral (2RR)), 1.20 ± 0.16 mm (3D spiral (1RR)), 1.14 ± 0.15 mm (2D spiral), and 1.21 ± 0.17 mm (TSE). Wall thickness reproducibility ranged from good (ICC = 0.65, 3D spiral (1RR)) to excellent (ICC = 0.87, 3D spiral (2RR)). High-resolution 3D spiral imaging with B2B-RMC permits coronary vessel wall assessment over multiple thin contiguous slices in a clinically feasible duration. Excellent reproducibility of the technique potentially enables studies of disease progression/regression. Copyright © 2010 Wiley-Liss, Inc.

  16. Development of automated welding process for field fabrication of thick walled pressure vessels. Fourth quarter, FY 1980

    SciTech Connect

    Not Available

    1980-12-19

    Progress is reported in research on the automated welding of heavy steel plate for the fabrication of pressure vessels. Information is included on: torch and shield adaptation; mechanical control of the welding process; welding parameters; joint design; filler wire optimizaton; nondestructive testing of welds; and weld repair. (LCL)

  17. Robustness of the P-U and lnD-U loop wave speed estimation methods: effects of the diastolic pressure decay and vessel wall non-linearities.

    PubMed

    Mynard, Jonathan P; Davidson, Malcolm R; Penny, Daniel J; Smolich, Joseph J

    2011-01-01

    Arterial wave speed estimated invasively from pressure (P) and velocity (U) measurements using the P-U loop method, or non-invasively from diameter (D) and U measurements using the lnD-U loop method, assume that during early systole 1) backward-running waves are absent and 2) wave speed is constant. These assumptions also form the basis of a method for correcting time lags between P (or lnD) and U in which the R(2) of the early-systolic linear regression is maximized. However, neither of the two assumptions are strictly valid in vivo, where the diastolic pressure decay from the previous beat may give rise to some non-zero backward-running P, U and wave intensity (WI) components, and the pressure-dependency of wave speed may lead to curvilinearity in the early-systolic P-U and lnD-U relations. Accordingly, this study assessed the robustness of three phase correction algorithms, (including two that are not dependent on the two assumptions stated above, i.e., aligning the times of the peak 2nd derivative or peak signal curvature) and of the P-U and lnD-U loop wave speed estimation methods under a range of diastolic decay rates and degrees of vessel wall non-linearity. Results from a simple computer model of the arterial circulation suggested that although an apparent phase lag may be introduced by assuming linearity, the magnitude of this phase lag is likely to be small considering the sample intervals normally used in experimental studies; however, under highly non-linear flow conditions, the apparent lag may be comparable to hardware-related lags. Predicted errors in estimated wave speed using the P-U loop method were generally less than 10%, while somewhat higher errors were found in the lnD-U loop method (up to 15-20%). In both, higher diastolic pressure decay rates were associated with higher wave speed errors, although this effect was eliminated by subtracting the extrapolated diastolic pressure curve from the measured pressure. Overall, each of the time lag

  18. The Deformation Rate of Smooth Muscle Cells in Vessel Walls After Short-Duration Heating Dilatation in a Porcine Model Ex Vivo and In Vivo.

    PubMed

    Kunio, Mie; Arai, Tsunenori

    2012-09-01

    We have proposed a novel short-duration thermal angioplasty with uniform temperature distribution. Although the dilatation mechanism of our short-duration heating dilatation was reported in our previous study, the influences on smooth muscle cells (SMCs) are not sufficiently understood. We studied the influences on SMCs in terms of shape change and discussed the relationship between the SMCs' shape change and dilatation mechanism ex vivo and in vivo. We found that the SMCs were fixed in the stretched condition after our short-duration heating dilatation both ex vivo and in vivo. The deformation rate of SMCs' shape, measured by the cells' nuclei, was increased with rising balloon maximum temperature (T(balloon)), and the same tendency was observed for the arterial dilatation rate. We hypothesize that the SMCs were fixed in the stretched condition because the arterial dilatation with our short-duration heating dilatation was performed without any plastic deformations of the vessel wall, causing the vessel wall itself to be stretched. We also prospect that the reasons for the positive correlation between the deformation rate of SMCs' shape and T(balloon) are that (i) the area heated over 60 °C was expanded with rising T(balloon), and (ii) the arterial dilatation rate was also increased with rising T(balloon).

  19. Inner and outer coronary vessel wall segmentation from CCTA using an active contour model with machine learning-based 3D voxel context-aware image force

    NASA Astrophysics Data System (ADS)

    Sivalingam, Udhayaraj; Wels, Michael; Rempfler, Markus; Grosskopf, Stefan; Suehling, Michael; Menze, Bjoern H.

    2016-03-01

    In this paper, we present a fully automated approach to coronary vessel segmentation, which involves calcification or soft plaque delineation in addition to accurate lumen delineation, from 3D Cardiac Computed Tomography Angiography data. Adequately virtualizing the coronary lumen plays a crucial role for simulating blood ow by means of fluid dynamics while additionally identifying the outer vessel wall in the case of arteriosclerosis is a prerequisite for further plaque compartment analysis. Our method is a hybrid approach complementing Active Contour Model-based segmentation with an external image force that relies on a Random Forest Regression model generated off-line. The regression model provides a strong estimate of the distance to the true vessel surface for every surface candidate point taking into account 3D wavelet-encoded contextual image features, which are aligned with the current surface hypothesis. The associated external image force is integrated in the objective function of the active contour model, such that the overall segmentation approach benefits from the advantages associated with snakes and from the ones associated with machine learning-based regression alike. This yields an integrated approach achieving competitive results on a publicly available benchmark data collection (Rotterdam segmentation challenge).

  20. Reduced capacity of tumour blood vessels to produce endothelium-derived relaxing factor: significance for blood flow modification.

    PubMed Central

    Tozer, G. M.; Prise, V. E.; Bell, K. M.; Dennis, M. F.; Stratford, M. R.; Chaplin, D. J.

    1996-01-01

    The effect of nitric oxide-dependent vasodilators on vascular resistance of tumours and normal tissue was determined with the aim of modifying tumour blood flow for therapeutic benefit. Isolated preparations of the rat P22 tumour and normal rat hindlimb were perfused ex vivo. The effects on tissue vascular resistance of administration of sodium nitroprusside (SNP) and the diazeniumdiolate (or NONO-ate) NOC-7, vasodilators which act via direct release of nitric oxide (NO), were compared with the effects of acetylcholine (ACh), a vasodilator which acts primarily via receptor stimulation of endothelial cells to release NO in the form of endothelium-derived relaxing factor (EDRF). SNP and NOC-7 effectively dilated tumour blood vessels after preconstriction with phenylephrine (PE) or potassium chloride (KCl) as indicated by a decrease in vascular resistance. SNP also effectively dilated normal rat hindlimb vessels after PE/KCl constriction. Vasodilatation in the tumour preparations was accompanied by a significant rise in nitrite levels measured in the tumour effluent. ACh induced a significant vasodilation in the normal hindlimb but an anomalous vasoconstriction in the tumour. This result suggests that tumours, unlike normal tissues are incapable of releasing NO (EDRF) in response to ACh. Capacity for EDRF production may represent a difference between tumour and normal tissue blood vessels, which could be exploited for selective pharmacological manipulation of tumour blood flow. PMID:8980396

  1. Platelet-derived growth factor over-expression in retinal progenitors results in abnormal retinal vessel formation.

    PubMed

    Edqvist, Per-Henrik D; Niklasson, Mia; Vidal-Sanz, Manuel; Hallböök, Finn; Forsberg-Nilsson, Karin

    2012-01-01

    Platelet-derived growth factor (PDGF) plays an important role in development of the central nervous system, including the retina. Excessive PDGF signaling is associated with proliferative retinal disorders. We reported previously that transgenic mice in which PDGF-B was over-expressed under control of the nestin enhancer, nes/tk-PdgfB-lacZ, exhibited enhanced apoptosis in the developing corpus striatum. These animals display enlarged lateral ventricles after birth as well as behavioral aberrations as adults. Here, we report that in contrast to the relatively mild central nervous system phenotype, development of the retina is severely disturbed in nes/tk-PdgfB-lacZ mice. In transgenic retinas all nuclear layers were disorganized and photoreceptor segments failed to develop properly. Since astrocyte precursor cells did not populate the retina, retinal vascular progenitors could not form a network of vessels. With time, randomly distributed vessels resembling capillaries formed, but there were no large trunk vessels and the intraocular pressure was reduced. In addition, we observed a delayed regression of the hyaloid vasculature. The prolonged presence of this structure may contribute to the other abnormalities observed in the retina, including the defective lamination.

  2. Skewness and flatness factors of the longitudinal velocity derivative in wall-bounded flows

    NASA Astrophysics Data System (ADS)

    Djenidi, Lyazid; Antonia, Robert A.; Talluru, Murali K.; Abe, Hiroyuki

    2017-06-01

    Hot-wire measurements are carried out in turbulent boundary layers over smooth and rough walls in order the assess the behavior of the skewness (S ) and flatness (F ) factors of the longitudinal velocity derivative as y , the distance from the wall, increases. The measurements are complemented by direct numerical simulations of a smooth wall turbulent channel flow. It is observed that, as the distance to the wall increases, S and F vary significantly before approaching a constant in the outer layer of the boundary layer. Further, S and F exhibit a nontrivial dependence on the Taylor microscale Reynolds number (Reλ). For example, in the region below about 0.2 δ (δ is the boundary layer thickness) where Reλ varies significantly, S and F strongly vary with Reλ and can be multivalued at a given Reλ. In the outer region, between 0.3 δ and 0.6 δ , S , F , and Reλ remain approximately constant. The channel flow direct numerical simulation data for S and F exhibit a similar behavior. These results point to the ambiguity that can arise when assessing the Reλ dependence of S and F in wall shear flows. In particular, the multivaluedness of S and F can lead to erroneous conclusions if y /δ is known only poorly, as is the case for the atmospheric shear layer (ASL). If the laboratory turbulent boundary layer is considered an adequate surrogate to the neutral ASL, then the behavior of S and F in the ASL is expected to be similar to that reported here.

  3. Determining the syringyl/guaiacyl lignin ratio in the vessel and fiber cell walls of transgenic Populus plants

    DOE PAGES

    Tolbert, Allison K.; Ma, Tao; Kalluri, Udaya C.; ...

    2016-06-20

    Observation of the spatial lignin distribution throughout the plant cell wall provides insight into the physicochemical characteristics of lignocellulosic biomass. The distribution of syringyl (S) and guaiacyl (G) lignin in cell walls of a genetically modified Populus deltoides and its corresponding empty vector control were analyzed with time-of-flight secondary ion mass spectrometry (ToF-SIMS) and then mapped to determine the S/G lignin ratio of the sample surface and specific regions of interest (ROIs). The surface characterizations of transgenic cross-sections within 1 cm vertical distance of each other on the stem possess similar S/G lignin ratios. Furthermore, the analysis of the ROIsmore » determined that there was a 50% decrease in the S/G lignin ratio of the transgenic xylem fiber cell walls.« less

  4. Evaluating middle cerebral artery atherosclerotic lesions in acute ischemic stroke using magnetic resonance T1-weighted 3-dimensional vessel wall imaging.

    PubMed

    Natori, Tatsunori; Sasaki, Makoto; Miyoshi, Mitsuharu; Ohba, Hideki; Katsura, Noriyuki; Yamaguchi, Mao; Narumi, Shinsuke; Kabasawa, Hiroyuki; Kudo, Kohsuke; Ito, Kenji; Terayama, Yasuo

    2014-04-01

    Atherosclerotic lesions in intracranial arteries are a leading cause of ischemic stroke. Magnetic resonance angiography (MRA) is often used to assess atherosclerotic changes by detecting luminal narrowing, whereas it cannot directly visualize atherosclerotic lesions. Here, we used a 3-dimensional vessel wall imaging (3D-VWI) technique to evaluate intracranial arterial wall changes in acute stroke. Eighteen consecutive patients with acute noncardioembolic stroke in the middle cerebral artery (MCA) territory who were prospectively examined with a 1.5-T magnetic resonance scanner were studied. T1-weighted (T1-W) 3D-VWI was obtained using a flow-sensitized 3D fast-spin echo technique. Wall thickening of MCA that suggests atherosclerotic plaques was visually evaluated and the contrast ratio (CR) of signal intensity of the lesions to that of the corpus callosum was calculated and compared with stenotic changes by MRA. Wall thickenings of the MCA ipsilateral and contralateral to the lesion were observed in almost all patients on 3D-VWI (94.4% and 94.4%, respectively), whereas MRA showed stenotic changes of 50% only in 1 patient (5.9%; P < .001). The CR of the thickened wall in the ipsilateral MCA was significantly higher than that in the contralateral MCA (median, .53 and .45, respectively; P = .028), suggesting of unstable plaques consisting of hemorrhage or lipid. The T1-W 3D-VWI can provide direct visualization of atherosclerotic lesions of the intracranial arteries in stroke patients, and it can detect signal change suggestive of unstable plaque. Copyright © 2014 National Stroke Association. Published by Elsevier Inc. All rights reserved.

  5. A phenomenological model for mechanically mediated growth, remodeling, damage, and plasticity of gel-derived tissue engineered blood vessels.

    PubMed

    Raykin, Julia; Rachev, Alexander I; Gleason, Rudolph L

    2009-10-01

    Mechanical stimulation has been shown to dramatically improve mechanical and functional properties of gel-derived tissue engineered blood vessels (TEBVs). Adjusting factors such as cell source, type of extracellular matrix, cross-linking, magnitude, frequency, and time course of mechanical stimuli (among many other factors) make interpretation of experimental results challenging. Interpretation of data from such multifactor experiments requires modeling. We present a modeling framework and simulations for mechanically mediated growth, remodeling, plasticity, and damage of gel-derived TEBVs that merge ideas from classical plasticity, volumetric growth, and continuum damage mechanics. Our results are compared with published data and suggest that this model framework can predict the evolution of geometry and material behavior under common experimental loading scenarios.

  6. A Phenomenological Model for Mechanically Mediated Growth, Remodeling, Damage, and Plasticity of Gel-Derived Tissue Engineered Blood Vessels

    PubMed Central

    Raykin, Julia; Rachev, Alexander I.

    2011-01-01

    Mechanical stimulation has been shown to dramatically improve mechanical and functional properties of gel-derived tissue engineered blood vessels (TEBVs). Adjusting factors such as cell source, type of extracellular matrix, cross-linking, magnitude, frequency, and time course of mechanical stimuli (among many other factors) make interpretation of experimental results challenging. Interpretation of data from such multifactor experiments requires modeling. We present a modeling framework and simulations for mechanically mediated growth, remodeling, plasticity, and damage of gel-derived TEBVs that merge ideas from classical plasticity, volumetric growth, and continuum damage mechanics. Our results are compared with published data and suggest that this model framework can predict the evolution of geometry and material behavior under common experimental loading scenarios. PMID:19831486

  7. Intra-aneurysmal flow with helix and mesh stent placement across side-wall aneurysm pore of a straight parent vessel.

    PubMed

    Liou, Tong-Miin; Liou, Shun-Nan; Chu, Kai-Lung

    2004-02-01

    Pulsatile flow fields in a cerebrovascular side-wall aneurysm model with a wide ostium after stenting are presented in terms of particle tracking velocimetry measurements and flow visualization. Among the stent parameters the shape, helix versus mesh, was selected to study its effect on the changes of intraaneurysmal hemodynamics for the reference of minimally invasive endovascular aneurysm treatment. The blocking ratio of the stents was fixed at 30%. The Womersley number was 3.9 and the mean, peak, and minimal Reynolds numbers based on the bulk average velocity and diameter of the parent vessel were 600, 850, and 300, respectively. Four consecutive flow-rate phases were selected to characterize the intra-aneurysmal flow. The results are characterized in terms of velocity vector field, regional average velocity, and intra-aneurysmal vorticity/circulation/wall shear stress. It is found that the hemodynamic features inside the aneurysm alter markedly with the shape of the stent and the size of the orifice. Both stents investigated induce favorable changes in the intra-aneurysmal flow stasis as well as direction and undulation of wall shear stresses. A comparison of the results of the helix to mesh stent shows that the former is more favorable for endovascular treatment.

  8. Derivation of jack movement influence coefficients as a basis for selecting wall contours giving reduced levels of interference in flexible walled test sections

    NASA Technical Reports Server (NTRS)

    Goodyer, M. J.

    1985-01-01

    This report covers work done in a transonic wind tunnel towards providing data on the influence of the movement of wall-control jacks on the Mach number perturbations along the test section. The data is derived using an existing streamline-curvature program, and in application is reduced to matrices of influence coefficients.

  9. Formation of three-dimensional cell/polymer constructs for bone tissue engineering in a spinner flask and a rotating wall vessel bioreactor

    NASA Technical Reports Server (NTRS)

    Sikavitsas, Vassilios I.; Bancroft, Gregory N.; Mikos, Antonios G.; McIntire, L. V. (Principal Investigator)

    2002-01-01

    The aim of this study is to investigate the effect of the cell culture conditions of three-dimensional polymer scaffolds seeded with rat marrow stromal cells (MSCs) cultured in different bioreactors concerning the ability of these cells to proliferate, differentiate towards the osteoblastic lineage, and generate mineralized extracellular matrix. MSCs harvested from male Sprague-Dawley rats were culture expanded, seeded on three-dimensional porous 75:25 poly(D,L-lactic-co-glycolic acid) biodegradable scaffolds, and cultured for 21 days under static conditions or in two model bioreactors (a spinner flask and a rotating wall vessel) that enhance mixing of the media and provide better nutrient transport to the seeded cells. The spinner flask culture demonstrated a 60% enhanced proliferation at the end of the first week when compared to static culture. On day 14, all cell/polymer constructs exhibited their maximum alkaline phosphatase activity (AP). Cell/polymer constructs cultured in the spinner flask had 2.4 times higher AP activity than constructs cultured under static conditions on day 14. The total osteocalcin (OC) secretion in the spinner flask culture was 3.5 times higher than the static culture, with a peak OC secretion occurring on day 18. No considerable AP activity and OC secretion were detected in the rotating wall vessel culture throughout the 21-day culture period. The spinner flask culture had the highest calcium content at day 14. On day 21, the calcium deposition in the spinner flask culture was 6.6 times higher than the static cultured constructs and over 30 times higher than the rotating wall vessel culture. Histological sections showed concentration of cells and mineralization at the exterior of the foams at day 21. This phenomenon may arise from the potential existence of nutrient concentration gradients at the interior of the scaffolds. The better mixing provided in the spinner flask, external to the outer surface of the scaffolds, may explain the

  10. Formation of three-dimensional cell/polymer constructs for bone tissue engineering in a spinner flask and a rotating wall vessel bioreactor.

    PubMed

    Sikavitsas, Vassilios I; Bancroft, Gregory N; Mikos, Antonios G

    2002-10-01

    The aim of this study is to investigate the effect of the cell culture conditions of three-dimensional polymer scaffolds seeded with rat marrow stromal cells (MSCs) cultured in different bioreactors concerning the ability of these cells to proliferate, differentiate towards the osteoblastic lineage, and generate mineralized extracellular matrix. MSCs harvested from male Sprague-Dawley rats were culture expanded, seeded on three-dimensional porous 75:25 poly(D,L-lactic-co-glycolic acid) biodegradable scaffolds, and cultured for 21 days under static conditions or in two model bioreactors (a spinner flask and a rotating wall vessel) that enhance mixing of the media and provide better nutrient transport to the seeded cells. The spinner flask culture demonstrated a 60% enhanced proliferation at the end of the first week when compared to static culture. On day 14, all cell/polymer constructs exhibited their maximum alkaline phosphatase activity (AP). Cell/polymer constructs cultured in the spinner flask had 2.4 times higher AP activity than constructs cultured under static conditions on day 14. The total osteocalcin (OC) secretion in the spinner flask culture was 3.5 times higher than the static culture, with a peak OC secretion occurring on day 18. No considerable AP activity and OC secretion were detected in the rotating wall vessel culture throughout the 21-day culture period. The spinner flask culture had the highest calcium content at day 14. On day 21, the calcium deposition in the spinner flask culture was 6.6 times higher than the static cultured constructs and over 30 times higher than the rotating wall vessel culture. Histological sections showed concentration of cells and mineralization at the exterior of the foams at day 21. This phenomenon may arise from the potential existence of nutrient concentration gradients at the interior of the scaffolds. The better mixing provided in the spinner flask, external to the outer surface of the scaffolds, may explain the

  11. Effects of Simulated Microgravity on Otolith Growth of Larval Zebrafish using a Rotating-Wall Vessel: Appropriate Rotation Speed and Fish Developmental Stage

    NASA Astrophysics Data System (ADS)

    Li, Xiaoyan; Anken, Ralf; Liu, Liyue; Wang, Gaohong; Liu, Yongding

    2017-02-01

    Stimulus dependence is a general feature of developing animal sensory systems. In this respect, it has extensively been shown earlier that fish inner ear otoliths can act as test masses as their growth is strongly affected by altered gravity such as hypergravity obtained using centrifuges, by (real) microgravity achieved during spaceflight or by simulated microgravity using a ground-based facility. Since flight opportunities are scarce, ground-based simulators of microgravity, using a wide variety of physical principles, have been developed to overcome this shortcoming. Not all of them, however, are equally well suited to provide functional weightlessness from the perspective of the biosystem under evaluation. Therefore, the range of applicability of a particular simulator has to be extensively tested. Earlier, we have shown that a Rotating-Wall Vessel (RWV) can be used to provide simulated microgravity for developing Zebrafish regarding the effect of rotation on otolith development. In the present study, we wanted to find the most effective speed of rotation and identify the appropriate developmental stage of Zebrafish, where effects are the largest, in order to provide a methodological basis for future in-depth analyses dedicated to the physiological processes underlying otolith growth at altered gravity. Last not least, we compared data on the effect of simulated microgravity on the size versus the weight of otoliths, since the size usually is measured in related studies due to convenience, but the weight more accurately approximates the physical capacity of an otolith. Maintaining embryos at 10 hours post fertilization for three days in the RWV, we found that 15 revolutions per minute (rpm) yielded the strongest effects on otolith growth. Maintenance of Zebrafish staged at 10 hpf, 1 day post fertilization (dpf), 4 dpf, 7 dpf and 14 dpf for three days at 15 rpm resulted in the most prominent effects in 7 dpf larvae. Weighing versus measuring the size of otoliths

  12. Effects of Simulated Microgravity on Otolith Growth of Larval Zebrafish using a Rotating-Wall Vessel: Appropriate Rotation Speed and Fish Developmental Stage

    NASA Astrophysics Data System (ADS)

    Li, Xiaoyan; Anken, Ralf; Liu, Liyue; Wang, Gaohong; Liu, Yongding

    2016-10-01

    Stimulus dependence is a general feature of developing animal sensory systems. In this respect, it has extensively been shown earlier that fish inner ear otoliths can act as test masses as their growth is strongly affected by altered gravity such as hypergravity obtained using centrifuges, by (real) microgravity achieved during spaceflight or by simulated microgravity using a ground-based facility. Since flight opportunities are scarce, ground-based simulators of microgravity, using a wide variety of physical principles, have been developed to overcome this shortcoming. Not all of them, however, are equally well suited to provide functional weightlessness from the perspective of the biosystem under evaluation. Therefore, the range of applicability of a particular simulator has to be extensively tested. Earlier, we have shown that a Rotating-Wall Vessel (RWV) can be used to provide simulated microgravity for developing Zebrafish regarding the effect of rotation on otolith development. In the present study, we wanted to find the most effective speed of rotation and identify the appropriate developmental stage of Zebrafish, where effects are the largest, in order to provide a methodological basis for future in-depth analyses dedicated to the physiological processes underlying otolith growth at altered gravity. Last not least, we compared data on the effect of simulated microgravity on the size versus the weight of otoliths, since the size usually is measured in related studies due to convenience, but the weight more accurately approximates the physical capacity of an otolith. Maintaining embryos at 10 hours post fertilization for three days in the RWV, we found that 15 revolutions per minute (rpm) yielded the strongest effects on otolith growth. Maintenance of Zebrafish staged at 10 hpf, 1 day post fertilization (dpf), 4 dpf, 7 dpf and 14 dpf for three days at 15 rpm resulted in the most prominent effects in 7 dpf larvae. Weighing versus measuring the size of otoliths

  13. Formation of three-dimensional cell/polymer constructs for bone tissue engineering in a spinner flask and a rotating wall vessel bioreactor

    NASA Technical Reports Server (NTRS)

    Sikavitsas, Vassilios I.; Bancroft, Gregory N.; Mikos, Antonios G.; McIntire, L. V. (Principal Investigator)

    2002-01-01

    The aim of this study is to investigate the effect of the cell culture conditions of three-dimensional polymer scaffolds seeded with rat marrow stromal cells (MSCs) cultured in different bioreactors concerning the ability of these cells to proliferate, differentiate towards the osteoblastic lineage, and generate mineralized extracellular matrix. MSCs harvested from male Sprague-Dawley rats were culture expanded, seeded on three-dimensional porous 75:25 poly(D,L-lactic-co-glycolic acid) biodegradable scaffolds, and cultured for 21 days under static conditions or in two model bioreactors (a spinner flask and a rotating wall vessel) that enhance mixing of the media and provide better nutrient transport to the seeded cells. The spinner flask culture demonstrated a 60% enhanced proliferation at the end of the first week when compared to static culture. On day 14, all cell/polymer constructs exhibited their maximum alkaline phosphatase activity (AP). Cell/polymer constructs cultured in the spinner flask had 2.4 times higher AP activity than constructs cultured under static conditions on day 14. The total osteocalcin (OC) secretion in the spinner flask culture was 3.5 times higher than the static culture, with a peak OC secretion occurring on day 18. No considerable AP activity and OC secretion were detected in the rotating wall vessel culture throughout the 21-day culture period. The spinner flask culture had the highest calcium content at day 14. On day 21, the calcium deposition in the spinner flask culture was 6.6 times higher than the static cultured constructs and over 30 times higher than the rotating wall vessel culture. Histological sections showed concentration of cells and mineralization at the exterior of the foams at day 21. This phenomenon may arise from the potential existence of nutrient concentration gradients at the interior of the scaffolds. The better mixing provided in the spinner flask, external to the outer surface of the scaffolds, may explain the

  14. Low-alloy steels for thick-walled pressure vessels. Summary report, February 1, 1980-January 31, 1982

    SciTech Connect

    Todd, J.A.; Chung, D.W.; Parker, E.R.

    1982-01-01

    This program aimed to modify existing commercial pressure vessel steels to provide strong, tough, creep resistant materials, with low hydrogen attack and temper embrittlement susceptibilities, which can also be field-fabricated into thick-section vessels for coal conversion systems. Emphasis was placed on determining the effects of Mn, Ni and Cr on the creep rupture and hydrogen attack susceptibilities of Cr-Mo steels. Hydrogen attack studies were also carried out on A533B and model alloy systems to investigate the role of alloy carbides in promoting resistance to hydrogen damage. Creep rupture fracture times were determined at 500, 560 and 600/sup 0/C for periods up to 2000 hours. The effects of cooling rate from the austenitizing temperature and tempering response on the microstructure of 3Cr-1Mo-1Mn-1Ni steel were studied. The carbide structures in all the alloy modifications were carefully characterized. Data were collected from preliminary weld bead-on-plate tests of A387 and temper embrittlement studies of A543 with mischmetal addition. The unloading compliance test technique for J/sub Ic/ measurements was completed for A533B specimens but shortage of material prevented testing of A387. The mechanical property, elevated temperature creep and hydrogen attack data suggested that addition of 0.75 Cr + 0.5 Mn + 1Ni was beneficial in reducing susceptibility to hydrogen damage but was detrimental to creep rupture properties. 44 figures, 14 tables.

  15. Identification of vessel wall anomalies in thoracic aortic aneurysms through optical coherence tomography and gradient-based strategies

    NASA Astrophysics Data System (ADS)

    Eguizabal, Alma; Real, Eusebio; Pontón, Alejandro; Calvo Diez, Marta; Val-Bernal, J. Fernando; Mayorga, Marta; Revuelta, José M.; López-Higuera, José M.; Conde, Olga M.

    2014-05-01

    Optical Coherence Tomography is a natural candidate for imaging biological structures just under tissue surface. Human thoracic aorta from aneurysms reveal elastin disorders and smooth muscle cell alterations when visualizing the media layer of the aortic wall, which is only some tens of microns in depth from surface. The resulting images require a suitable processing to enhance interesting disorder features and to use them as indicators for wall degradation, converting OCT into a hallmark for diagnosis of risk of aneurysm under intraoperative conditions. This work proposes gradient-based digital image processing approaches to conclude this risk. These techniques are believed to be useful in these applications as aortic wall disorders directly affect the refractive index of the tissue, having an effect on the gradient of the tissue reflectivity that conform the OCT image. Preliminary results show that the direction of the gradient contains information to estimate the tissue abnormality score. The detection of the edges of the OCT image is performed using the Canny algorithm. The edges delineate tissue disorders in the region of interest and isolate the abnormalities. These edges can be quantified to estimate a degradation score. Furthermore, the direction of the gradient seems to be a promising enhancement technique, as it detects areas of homogeneity in the region of interest. Automatic results from gradient-based strategies are finally compared to the histopathological global aortic score, which accounts for each risk factor presence and seriousness.

  16. In-vessel calibration of the imaging diagnostics for the real-time protection of the JET ITER-like wall

    NASA Astrophysics Data System (ADS)

    Huber, V.; Huber, A.; Kinna, D.; Balboa, I.; Collins, S.; Conway, N.; Drewelow, P.; Maggi, C. F.; Matthews, G. F.; Meigs, A. G.; Mertens, Ph.; Price, M.; Sergienko, G.; Silburn, S.; Wynn, A.; Zastrow, K.-D.

    2016-11-01

    The in situ absolute calibration of the JET real-time protection imaging system has been performed for the first time by means of radiometric light source placed inside the JET vessel and operated by remote handling. High accuracy of the calibration is confirmed by cross-validation of the near infrared (NIR) cameras against each other, with thermal IR cameras, and with the beryllium evaporator, which lead to successful protection of the JET first wall during the last campaign. The operation temperature ranges of NIR protection cameras for the materials used on JET are Be 650-1600 °C, W coating 600-1320 °C, and W 650-1500 °C.

  17. In-vessel calibration of the imaging diagnostics for the real-time protection of the JET ITER-like wall

    SciTech Connect

    Huber, V.; Huber, A.; Mertens, Ph.; Sergienko, G.; Kinna, D.; Balboa, I.; Collins, S.; Conway, N.; Maggi, C. F.; Matthews, G. F.; Meigs, A. G.; Price, M.; Silburn, S.; Zastrow, K.-D.; Drewelow, P.; Wynn, A.

    2016-11-15

    The in situ absolute calibration of the JET real-time protection imaging system has been performed for the first time by means of radiometric light source placed inside the JET vessel and operated by remote handling. High accuracy of the calibration is confirmed by cross-validation of the near infrared (NIR) cameras against each other, with thermal IR cameras, and with the beryllium evaporator, which lead to successful protection of the JET first wall during the last campaign. The operation temperature ranges of NIR protection cameras for the materials used on JET are Be 650-1600 °C, W coating 600-1320 °C, and W 650-1500 °C.

  18. Adventitial Vessel Growth and Progenitor Cells Activation in an Ex Vivo Culture System Mimicking Human Saphenous Vein Wall Strain after Coronary Artery Bypass Grafting

    PubMed Central

    Prandi, Francesca; Piola, Marco; Soncini, Monica; Colussi, Claudia; D’Alessandra, Yuri; Penza, Eleonora; Agrifoglio, Marco; Vinci, Maria Cristina; Polvani, Gianluca; Gaetano, Carlo; Fiore, Gianfranco Beniamino; Pesce, Maurizio

    2015-01-01

    Saphenous vein graft disease is a timely problem in coronary artery bypass grafting. Indeed, after exposure of the vein to arterial blood flow, a progressive modification in the wall begins, due to proliferation of smooth muscle cells in the intima. As a consequence, the graft progressively occludes and this leads to recurrent ischemia. In the present study we employed a novel ex vivo culture system to assess the biological effects of arterial-like pressure on the human saphenous vein structure and physiology, and to compare the results to those achieved in the presence of a constant low pressure and flow mimicking the physiologic vein perfusion. While under both conditions we found an activation of Matrix Metallo-Proteases 2/9 and of microRNAs-21/146a/221, a specific effect of the arterial-like pressure was observed. This consisted in a marked geometrical remodeling, in the suppression of Tissue Inhibitor of Metallo-Protease-1, in the enhanced expression of TGF-β1 and BMP-2 mRNAs and, finally, in the upregulation of microRNAs-138/200b/200c. In addition, the veins exposed to arterial-like pressure showed an increase in the density of the adventitial vasa vasorum and of cells co-expressing NG2, CD44 and SM22α markers in the adventitia. Cells with nuclear expression of Sox-10, a transcription factor characterizing multipotent vascular stem cells, were finally found in adventitial vessels. Our findings suggest, for the first time, a role of arterial-like wall strain in the activation of pro-pathologic pathways resulting in adventitial vessels growth, activation of vasa vasorum cells, and upregulation of specific gene products associated to vascular remodeling and inflammation. PMID:25689822

  19. Adventitial vessel growth and progenitor cells activation in an ex vivo culture system mimicking human saphenous vein wall strain after coronary artery bypass grafting.

    PubMed

    Prandi, Francesca; Piola, Marco; Soncini, Monica; Colussi, Claudia; D'Alessandra, Yuri; Penza, Eleonora; Agrifoglio, Marco; Vinci, Maria Cristina; Polvani, Gianluca; Gaetano, Carlo; Fiore, Gianfranco Beniamino; Pesce, Maurizio

    2015-01-01

    Saphenous vein graft disease is a timely problem in coronary artery bypass grafting. Indeed, after exposure of the vein to arterial blood flow, a progressive modification in the wall begins, due to proliferation of smooth muscle cells in the intima. As a consequence, the graft progressively occludes and this leads to recurrent ischemia. In the present study we employed a novel ex vivo culture system to assess the biological effects of arterial-like pressure on the human saphenous vein structure and physiology, and to compare the results to those achieved in the presence of a constant low pressure and flow mimicking the physiologic vein perfusion. While under both conditions we found an activation of Matrix Metallo-Proteases 2/9 and of microRNAs-21/146a/221, a specific effect of the arterial-like pressure was observed. This consisted in a marked geometrical remodeling, in the suppression of Tissue Inhibitor of Metallo-Protease-1, in the enhanced expression of TGF-β1 and BMP-2 mRNAs and, finally, in the upregulation of microRNAs-138/200b/200c. In addition, the veins exposed to arterial-like pressure showed an increase in the density of the adventitial vasa vasorum and of cells co-expressing NG2, CD44 and SM22α markers in the adventitia. Cells with nuclear expression of Sox-10, a transcription factor characterizing multipotent vascular stem cells, were finally found in adventitial vessels. Our findings suggest, for the first time, a role of arterial-like wall strain in the activation of pro-pathologic pathways resulting in adventitial vessels growth, activation of vasa vasorum cells, and upregulation of specific gene products associated to vascular remodeling and inflammation.

  20. Characterization of the osteoblast-like cell phenotype under microgravity conditions in the NASA-approved Rotating Wall Vessel bioreactor (RWV).

    PubMed

    Rucci, Nadia; Migliaccio, Silvia; Zani, Bianca Maria; Taranta, Anna; Teti, Anna

    2002-01-01

    Weightlessness induces bone loss in humans and animal models. We employed the NASA-approved Rotating Wall Vessel bioreactor (RWV) to develop osteoblast-like cell cultures under microgravity and evaluate osteoblast phenotype and cell function. Rat osteoblast-like cell line (ROS.SMER#14) was grown in the RWV at a calculated gravity of 0.008g. For comparison, aliquots of cells were grown in conventional tissue culture dishes or in Non-Rotating Wall Vessels (N-RWV) maintained at unit gravity. In RWV, osteoblasts showed high levels of alkaline phosphatase expression and activity, and elevated expression of osteopontin, osteocalcin, and bone morphogenetic protein 4 (BMP-4). In contrast, the expression of osteonectin, bone sialoprotein II and BMP-2 were unaltered compared to cells in conventional culture conditions. These observations are consistent with a marked osteoblast phenotype. However, we observed that in RWV osteoblasts showed reduced proliferation. Furthermore, DNA nucleosome-size fragmentation was revealed both morphologically, by in situ staining with the Thymine-Adenine binding dye bis-benzimide, and electrophoretically, by DNA laddering. Surprisingly, no p53, nor bcl-2/bax, nor caspase 8 pathways were activated by microgravity, therefore the intracellular cascade leading to programmed cell death remains to be elucidated. Finally, consistent with an osteoclast-stimulating effect by microgravity, osteoblasts cultured in RWV showed upregulation of interleukin-6 (IL-6) mRNA, and IL-6 proved to be active at stimulating osteoclast formation and resorbing activity in vitro. We conclude that under microgravity, reduced osteoblast life span and enhanced IL-6 expression may result in inefficient osteoblast- and increased osteoclast-activity, respectively, thus potentially contributing to bone loss in individuals subjected to weightlessness.

  1. Reconstitution of hepatic tissue architectures from fetal liver cells obtained from a three-dimensional culture with a rotating wall vessel bioreactor.

    PubMed

    Ishikawa, Momotaro; Sekine, Keisuke; Okamura, Ai; Zheng, Yun-wen; Ueno, Yasuharu; Koike, Naoto; Tanaka, Junzo; Taniguchi, Hideki

    2011-06-01

    Reconstitution of tissue architecture in vitro is important because it enables researchers to investigate the interactions and mutual relationships between cells and cellular signals involved in the three-dimensional (3D) construction of tissues. To date, in vitro methods for producing tissues with highly ordered structure and high levels of function have met with limited success although a variety of 3D culture systems have been investigated. In this study, we reconstituted functional hepatic tissue including mature hepatocyte and blood vessel-like structures accompanied with bile duct-like structures from E15.5 fetal liver cells, which contained more hepatic stem/progenitor cells comparing with neonatal liver cells. The culture was performed in a simulated microgravity environment produced by a rotating wall vessel (RWV) bioreactor. The hepatocytes in the reconstituted 3D tissue were found to be capable of producing albumin and storing glycogen. Additionally, bile canaliculi between hepatocytes, characteristics of adult hepatocyte in vivo were also formed. Apart from this, bile duct structure secreting mucin was shown to form complicated tubular branches. Furthermore, gene expression analysis by semi-quantitative RT-PCR revealed the elevated levels of mature hepatocyte markers as well as genes with the hepatic function. With RWV culture system, we could produce functionally reconstituted liver tissue and this might be useful in pharmaceutical industry including drug screening and testing and other applications such as an alternative approach to experimental animals.

  2. The hematopoietic chemokine CXCL12 promotes integration of human endothelial colony forming cell-derived cells into immature vessel networks.

    PubMed

    Newey, Sarah E; Tsaknakis, Grigorios; Khoo, Cheen P; Athanassopoulos, Thanassi; Camicia, Rosalba; Zhang, Youyi; Grabowska, Rita; Harris, Adrian L; Roubelakis, Maria G; Watt, Suzanne M

    2014-11-15

    Proangiogenic factors, vascular endothelial growth factor (VEGF), and fibroblast growth factor-2 (FGF-2) prime endothelial cells to respond to "hematopoietic" chemokines and cytokines by inducing/upregulating expression of the respective chemokine/cytokine receptors. Coculture of human endothelial colony forming cell (ECFC)-derived cells with human stromal cells in the presence of VEGF and FGF-2 for 14 days resulted in upregulation of the "hematopoietic" chemokine CXCL12 and its CXCR4 receptor by day 3 of coculture. Chronic exposure to the CXCR4 antagonist AMD3100 in this vasculo/angiogenesis assay significantly reduced vascular tubule formation, an observation recapitulated by delayed AMD3100 addition. While AMD3100 did not affect ECFC-derived cell proliferation, it did demonstrate a dual action. First, over the later stages of the 14-day cocultures, AMD3100 delayed tubule organization into maturing vessel networks, resulting in enhanced endothelial cell retraction and loss of complexity as defined by live cell imaging. Second, at earlier stages of cocultures, we observed that AMD3100 significantly inhibited the integration of exogenous ECFC-derived cells into established, but immature, vascular networks. Comparative proteome profiler array analyses of ECFC-derived cells treated with AMD3100 identified changes in expression of potential candidate molecules involved in adhesion and/or migration. Blocking antibodies to CD31, but not CD146 or CD166, reduced the ECFC-derived cell integration into these extant vascular networks. Thus, CXCL12 plays a key role not only in endothelial cell sensing and guidance, but also in promoting the integration of ECFC-derived cells into developing vascular networks.

  3. PERIPHERAL NERVE-DERIVED CXCL12 AND VEGF-A REGULATE THE PATTERNING OF ARTERIAL VESSEL BRANCHING IN DEVELOPING LIMB SKIN

    PubMed Central

    Li, Wenling; Kohara, Hiroshi; Uchida, Yutaka; James, Jennifer M.; Soneji, Kosha; Cronshaw, Darran G.; Zou, Yong-Rui; Nagasawa, Takashi; Mukouyama, Yoh-suke

    2013-01-01

    SUMMARY In developing limb skin, peripheral nerves provide a spatial template that controls the branching pattern and differentiation of arteries. Our previous studies indicate that nerve-derived VEGF-A is required for arterial differentiation but not for nerve-vessel alignment. In this study, we demonstrate that nerve-vessel alignment depends on the activity of Cxcl12-Cxcr4 chemokine signaling. Genetic inactivation of Cxcl12-Cxcr4 signaling perturbs nerve-vessel alignment, and abolishes arteriogenesis. Further in vitro assays allow us to uncouple nerve-vessel alignment and arteriogenesis, revealing that nerve-derived Cxcl12 stimulates endothelial cell migration, while nerve-derived VEGF-A is responsible for arterial differentiation. These findings suggest a coordinated sequential action in which nerve-Cxcl12 functions over a distance to recruit vessels to align with nerves and subsequent arterial differentiation presumably requires a local-action of nerve-VEGF-A in the nerve-associated vessels. PMID:23395391

  4. Trans isomeric octadecenoic acids are related inversely to arachidonic acid and DHA and positively related to mead acid in umbilical vessel wall lipids.

    PubMed

    Decsi, Tamás; Boehm, Günther; Tjoonk, H M Ria; Molnár, Szilárd; Dijck-Brouwer, D A Janneke; Hadders-Algra, Mijna; Martini, Ingrid A; Muskiet, Frits A J; Boersma, E Rudy

    2002-10-01

    Long-chain PUFA play an important role in early human neurodevelopment. Significant inverse correlations were reported between values of trans isomeric and long-chain PUFA in plasma lipids of preterm infants and children aged 1-15 yr as well as in venous cord blood lipids of full-term infants. Here we report FA compositional data of cord blood vessel wall lipids in 308 healthy, full-term infants (gestational age: 39.7 +/- 1.2 wk, birth weight: 3528 +/- 429 g, mean +/- SD). The median (interquartile range) of the sum of 18-carbon trans FA was 0.22 (0.13) % w/w in umbilical artery and 0.16 (0.10) % w/w in umbilical vein lipids. Nonparametric correlation analysis showed significant inverse correlations between the sum of 18-carbon trans FA and both arachidonic acid and DHA in artery (r = -0.38, P < 0.01, and r = -0.20, P < 0.01) and vein (r = -0.36, P < 0.01, and -0.17, P < 0.01) wall lipids. In addition, the sum of 18-carbon trans FA was significantly positively correlated to Mead acid, a general indicator of EFA deficiency, in both artery (r = +0.35, P < 0.01) and vein (r = +0.31, P< 0.01) wall lipids. The present results obtained in a large group of full-term infants suggest that maternal trans FA intake is inversely associated with long-chain PUFA status of the infant at birth.

  5. Remodeling of the Vessel Wall after Copper-Induced Injury Is Highly Attenuated in Mice with a Total Deficiency of Plasminogen Activator Inhibitor-1

    PubMed Central

    Ploplis, Victoria A.; Cornelissen, Ivo; Sandoval-Cooper, Mayra J.; Weeks, Lisa; Noria, Francisco A.; Castellino, Francis J.

    2001-01-01

    Clinical studies have indicated that high plasma levels of fibrinogen, or decreased fibrinolytic potential, are conducive to an increased risk of cardiovascular disease. Other investigations have shown that insoluble fibrin promotes atherosclerotic lesion formation by affecting smooth muscle cell proliferation, collagen deposition, and cholesterol accumulation. To directly assess the physiological impact of an imbalanced fibrinolytic system on both early and late stages of this disease, mice deficient for plasminogen activator inhibitor-1 (PAI-1−/−) were used in a model of vascular injury/repair, and the resulting phenotype compared to that of wild-type (WT) mice. A copper-induced arterial injury was found to generate a lesion with characteristics similar to many of the clinical features of atherosclerosis. Fibrin deposition in the injured arterial wall at early (7 days) and late (21 days) times after copper cuff placement was prevalent in WT mice, but was greatly diminished in PAI-1−/− mice. A multilayered neointima with enhanced collagen deposition was evident at day 21 in WT mice. In contrast, only diffuse fibrin was identified in the adventitial compartments of arteries from PAI-1−/− mice, with no evidence of a neointima. Neovascularization was observed in the adventitia and was more extensive in WT arteries, relative to PAI-1−/− arteries. Additionally, enhanced PAI-1 expression and fat deposition were seen only in the arterial walls of WT mice. The results of this study emphasize the involvement of the fibrinolytic system in vascular repair processes after injury and indicate that alterations in the fibrinolytic balance in the vessel wall have a profound effect on the development and progression of vascular lesion formation. PMID:11141484

  6. Formation and differentiation of three-dimensional rat marrow stromal cell culture on microcarriers in a rotating-wall vessel

    NASA Technical Reports Server (NTRS)

    Qiu, Q.; Ducheyne, P.; Gao, H.; Ayyaswamy, P.

    1998-01-01

    Using a high aspect ratio vessel (HARV), this study investigated the formation of 3-D rat marrow stromal cell culture on microcarriers and the expression of bone-related biochemical markers under conditions of simulated microgravity. In addition, it calculated the shear stresses imparted on the surface of microcarriers of different densities by the medium fluid in an HARV. Secondary rat marrow stromal cells were cultured on two types of microcarriers, Cytodex-3 beads and modified bioactive glass particles. Examination of cellular morphology by scanning electron microscopy revealed the presence of three-dimensional multicellular aggregates consisting of multiple cell-covered Cytodex-3 microcarriers bridged together. Mineralization was observed in the aggregates. Spherical cell-bead aggregates were observed in an HARV, while cell-bead assemblies were mostly loosely packed in a chain-like or branched structure in a cell bag. The expressions of alkaline phosphatase activity, collagen type I, and osteopontin were shown via the use of histochemical staining, immunolabeling, and confocal scanning electron microscopy. Using a numerical approach, it was found that at a given rotational speed and for a given culture medium, a larger density difference between the microcarrier and the culture medium (e.g., a modified bioactive glass particle) imparted a higher maximum shear stress on the microcarrier.

  7. Acetylcholine releases endothelium-derived hyperpolarizing factor and EDRF from rat blood vessels.

    PubMed Central

    Chen, G.; Suzuki, H.; Weston, A. H.

    1988-01-01

    1. The effects of haemoglobin and methylene blue on the acetylcholine (ACh)-induced electrical and mechanical responses of smooth muscle cells were investigated in rat aorta and rat main pulmonary artery. 2. When the endothelium was intact, ACh induced a transient hyperpolarization and sustained relaxation of tissues precontracted with noradrenaline. Both hyperpolarization and relaxation were absent in preparations without endothelium. 3. Haemoglobin and methylene blue inhibited the ACh-induced relaxation, but not the transient hyperpolarization. 4. In aorta with an intact endothelium, ACh produced an increase in both the rate of 86Rb efflux and tissue cyclic GMP levels. The changes in ion flux were unaffected by either haemoglobin or methylene blue in concentrations which almost abolished the increase in cyclic GMP concentrations. 5. In arteries with an intact endothelium, indomethacin had no effect on the ACh-induced electrical and mechanical responses or on the increase in 86Rb efflux and tissue cyclic GMP levels. 6. It is concluded that in the rat aorta and rat main pulmonary artery, ACh releases two different substances, an endothelium-derived relaxing factor (EDRF) and a hyperpolarizing factor (EDHF), from the endothelial cells. Neither substance appears to be derived from a pathway dependent on cyclo-oxygenase. EDHF seems to play a minor role in the relaxation of noradrenaline-induced contractions. PMID:2851359

  8. Wall discontinuities and increased expression of vascular endothelial growth factor-A and vascular endothelial growth factor receptors 1 and 2 in endometrial blood vessels of women with menorrhagia.

    PubMed

    Mints, Miriam; Hultenby, Kjell; Zetterberg, Eva; Blomgren, Bo; Falconer, Christian; Rogers, Rick; Palmblad, Jan

    2007-09-01

    To investigate whether the structure or regulation of the growth of endometrial blood vessels might be abnormal in women with idiopathic menorrhagia (IM). Perturbation of angiogenesis is associated with IM. Prospective, clinical study. Department of gynecology at a university hospital. Twenty-four patients with IM, and 18 women with eumenorrhea. Endometrial biopsy samples underwent immunohistochemical staining for CD34, CD31, von Willebrand factor, vascular endothelial growth factor (VEGF)-A, and VEGF receptors 1 and 2. Differences in immunostaining for these markers by computer-assisted stereological analysis. Endometrial vessels in patients and controls manifested focal discontinuities, or gaps, in endothelial staining for CD34, CD31, and von Willebrand factor. Electron and confocal microscopy revealed that perivascular cells, probably pericytes, covered these gaps in the vessel wall. The relative size of the gaps was significantly greater in patients with IM than in controls. Vessel circumference was also larger, and more vessels were positive for VEGF-A and for VEGF receptors 1 and 2, in patients than in controls. Gap size was significantly correlated with the number of vessels expressing VEGF-A or VEGF receptor 1. Endometrial blood vessels possess a discrete morphology that is characterized by endothelial gaps, and these gaps [1] are more pronounced in women with IM, [2] are related to overexpression of VEGF-A and VEGF receptor 1, and [3] might contribute to IM, e.g., by destablizing vessels.

  9. Detection of myocardial ischemia by vessel-specific leads derived from the 12-lead electrocardiogram and its subsets.

    PubMed

    Horácek, B Milan; Mirmoghisi, Maryam; Warren, James W; Wagner, Galen S; Wang, John J

    2008-01-01

    Currently used electrocardiographic criteria for identifying patients with ST-elevation myocardial infarction (STEMI) perform with high specificity but low sensitivity. Our aim was to enhance ischemia-detection ability of conventional STEMI criteria based on 12-lead electrocardiogram (ECG) by adding new criteria using 3 vessel-specific leads (VSLs) derived from 12-lead ECG. Study data consisted of 12-lead ECGs acquired during 99 ischemic episodes caused by balloon inflation in, respectively, left anterior descending coronary artery (LAD; n = 35), right coronary artery (RCA; n = 47), and left circumflex coronary artery (LCx; n = 17). ST deviation was measured at J point in 12 standard leads, and for 3 VSLs, its value was derived from 12-lead ECG by using 8 independent predictor leads or just a pair of precordial leads combined with a pair of limb leads. Mean values of sensitivity (SE) and specificity (SP) of ischemia detection achieved with conventional STEMI vs VSL criteria were then obtained from bootstrap trials. We found that the detection of ischemic state by conventional criteria achieved the mean SE/SP of 60%/96% in the total set of ischemic episodes, 74%/97% in the LAD subgroup, 60%/94% in the RCA subgroup, and 36%/100% in the LCx subgroup. In comparison, the mean SE/SP values of VSLs derived from 8 independent leads of 12-lead ECG were, at 125-microV threshold, 76%(*)/96% in the total set, 91%(*)/97% in the LAD subgroup, 70%/94% in the RCA subgroup, and 71%(*)/100% in the LCx subgroup (with asterisk denoting a statistically significant increase). The mean SE/SP of VSLs derived from some of the 4-predictor lead sets (namely, those including lead V(3)) matched or exceeded values achieved by VSLs derived from 8 predictors; for instance, with predictor leads I, II, V(3), V(6) derived VSLs attained at 125-microV threshold the mean SE/SP of 80%(*)/95% in the total set, 91%(*)/97% in the LAD subgroup, 74%/92% in the RCA subgroup, and 71%(*)/100% in the LCx

  10. Hyaluronic acid accumulation and endothelial cell detachment in intimal thickening of the vessel wall. The normal and genetically defective ductus arteriosus.

    PubMed

    De Reeder, E G; Girard, N; Poelmann, R E; Van Munsteren, J C; Patterson, D F; Gittenberger-De Groot, A C

    1988-09-01

    The closing ductus arteriosus (DA) was studied as a model for the development of intimal thickening of vessel walls using ultrastructural and immunohistochemical techniques. The material consisted of DA from neonatal dogs of three types: normal beagles, DA-defective pups from a line of mixed poodles with a genetic defect in the closure of the DA leading to persistent ductus arteriosus (PDA line), and normal litter-mates of DA-defective pups in the PDA line. The DA of the normal litter-mates of DA-defective pups did not differ from those of normal beagles. In the DA of normal beagles and normal PDA-line pups, closure is preceded by intimal thickening characterized by formation of a widened subendothelial region (SR), detachment of endothelial cells, invagination of endothelial cells, and migration of smooth muscle cells into the SR. It was observed that immediately before and after endothelial cell detachment, there was an increase in hyaluronic acid (HA) in the SR and inner media. In the DA-defective pups, the increase in hyaluronic acid failed to occur and there was no intimal thickening. The SR failed to expand, endothelium remained attached to the internal elastic membrane, and there was no invagination of endothelium or migration of smooth muscle cells. It is hypothesized that the increased synthesis of HA is an important early event leading to intimal thickening in the normal DA and perhaps to abnormal intimal thickening of other vessels. By its hygroscopic properties, HA may be directly involved in the formation of a wide SR, inducing endothelial cell detachment and favoring smooth muscle cell migration. In affected pups of the PDA line, there is a genetically-determined "block" in the normal process of intimal thickening at or before the initiation of increased HA synthesis.

  11. Coronary atherosclerosis and dilation in hyper IgE syndrome patients: Depiction by magnetic resonance vessel wall imaging and pathological correlation.

    PubMed

    Abd-Elmoniem, Khaled Z; Ramos, Nadine; Yazdani, Saami K; Ghanem, Ahmed M; Holland, Steven M; Freeman, Alexandra F; Gharib, Ahmed M

    2017-03-01

    Autosomal dominant hyper-IgE (AD-HIES) is a primary immunodeficiency caused by mutations in STAT3. Elevated levels of IgE, an ineffective immune response, connective tissue abnormalities, and coronary arterial dilation and tortuosity characterize AD-HIES. To date, coronary artery evaluation in AD-HIES patients has been limited to lumenography measurements. Direct in vivo coronary vessel wall (VW) imaging may allow for better interrogation of coronary vessel abnormalities. The goal of this prospective study was to evaluate the coronary VW of AD-HIES patients using Magnetic Resonance Imaging (MRI) and histology. VW image findings were compared in healthy subjects and subjects with coronary atherosclerotic disease (CAD). A total of 28 subjects (10 with AD-HIES, 8 healthy, 10 with CAD) were studied by coronary VW MRI imaging. Additionally, a post-mortem coronary artery from one VW imaged AD-HIES patient was examined. Coronary VW in AD-HIES was thicker than in healthy controls but not significantly different from VW thickness in CAD subjects. AD-HIES coronaries showed increased VW area compared to healthy controls and CAD subjects. On histology, the AD-HIES coronary artery had findings consistent with atherosclerotic plaque, but had minimal luminal narrowing, deficient adventitia thickening and absence of both internal and external elastic laminae. This is the first study to demonstrate subclinical coronary atherosclerosis in AD-HIES patients on VW imaging by MRI. Histologic evaluation confirmed the presence of atherosclerosis with lack of supportive adventitial thickening and elastic components. These findings suggest mechanisms for coronary dilation in AD-HIES and thereby help direct clinical management. Published by Elsevier B.V.

  12. Interaction with damaged vessel wall in vivo in humans induces platelets to express CD40L resulting in endothelial activation with no effect of aspirin intake.

    PubMed

    Giannini, Silvia; Falcinelli, Emanuela; Bury, Loredana; Guglielmini, Giuseppe; Rossi, Roberta; Momi, Stefania; Gresele, Paolo

    2011-06-01

    Activated platelets express CD40L on their plasma membrane and release the soluble fragment sCD40L. The interaction between platelet surface CD40L and endothelial cell CD40 leads to the activation of endothelium contributing to atherothrombosis. Few studies have directly demonstrated an increased expression of platelet CD40L in conditions of in vivo platelet activation in humans, and no data are available on its relevance for endothelial activation. We aimed to assess whether platelets activated in vivo at a localized site of vascular injury in humans express CD40L and release sCD40L, whether the level of platelet CD40L expression attained in vivo is sufficient to induce endothelial activation, and whether platelet CD40L expression is inhibited by aspirin intake. We used the skin-bleeding-time test as a model to study the interaction between platelets and a damaged vessel wall by measuring CD40L in the blood emerging from a skin wound in vivo in healthy volunteers. In some experiments, shed blood was analyzed before and 1 h after the intake of 500 mg of aspirin. Platelets from the bleeding-time blood express CD40L and release soluble sCD40L, in a time-dependent way. In vivo platelet CD40L expression was mild but sufficient to induce VCAM-1 expression and IL-8 secretion in coincubation experiments with cultured human endothelial cells. Moreover, platelets recovered from the bleeding-time blood activated endothelial cells; an anti-CD40L antibody blocked this effect. On the contrary, the amount of sCD40L released by activated platelets at a localized site of vascular injury did not reach the concentrations required to induce endothelial cell activation. Soluble monocyte chemoattractant protein-1, a marker of endothelium activation, was increased in shed blood and correlated with platelet CD40L expression. Aspirin intake did not inhibit CD40L expression by platelets in vivo. We concluded that CD40L expressed by platelets in vivo in humans upon contact with a damaged

  13. Enzymic Analysis of Feruloylated Arabinoxylans (Feraxan) Derived from Zea mays Cell Walls 1

    PubMed Central

    Nishitani, Kazuhiko; Nevins, Donald J.

    1989-01-01

    Structural features of feruloylated arabinoxylan (feraxan) present in Zea mays L. (hybrid B 73 × Mo 17) coleoptile cell walls have been studied using a purified feraxan-dissociating enzyme (feraxanase) and an α-arabinofuranosidase. This experimental approach has demonstrated the following. (a) Feraxanase dissociated ca. 20% (dry weight basis) of the maize wall preparation. The predominant oligosaccharides enzymically liberated were allocated into seven major subfractions designated A-1 (0.8%), B-1 (1.6%), B-2 (2.4%), B-3 (4.6%), C-1 (1.0%), C-2 (4.2%), and C-3 (0.3%). Values in parentheses reflect the percentage of the wall associated with each subfraction. Subfractions represent samples enriched in different degrees of polymerization, sugar composition, linkage arrangements, and phenolic acid content. (b) B-1, B-2, and B-3 fractions are not feruloylated and have smaller molecular mass (less than 104 kilodaltons) and consist chiefly of t-arabinosyl-5-arabinosyl, 4-xylosyl, 2,4/3,4-xylosyl, and glucuronosyl residues, suggesting that these fragments constitute nonferuloylated regions of arabinoxylan. (c) C-2 and C-3 fractions contain ferulic acid (6.2% and 12.1%, respectively) and are similar to the B series in their sugar linkage arrangements but were derived from feruloylated regions. (d) Alkali treatment of the C-2 fraction decreases the molecular size of the fragment and liberates phenolic acids. The results suggest the presence of alkaline-labile links, probably diferulate bridges. (e) A-1 and C-1 fractions are larger (more than 5 × 105 kilodalton) and contain t-galactosyl-, 4-galactosyl, 2,4-rhamnosyl-residues, galacturonic acid, and the sugar linkage arrangements common to other fractions. The A-1 fraction is not feruloylated, whereas C-1 fraction contains 0.5% ferulic acid. The presence of galactose, rhamnose, and galacturonic acid suggests that pectic polymers, probably homopolygalacturonans and rhamnogalacturonans, are linked to nonferuloylated and

  14. Tamoxifen up-regulates catalase production, inhibits vessel wall neutrophil infiltration, and attenuates development of experimental abdominal aortic aneurysms.

    PubMed

    Grigoryants, Vladimir; Hannawa, Kevin K; Pearce, Charles G; Sinha, Indranil; Roelofs, Karen J; Ailawadi, Gorav; Deatrick, Kristopher B; Woodrum, Derek T; Cho, Brenda S; Henke, Peter K; Stanley, James C; Eagleton, Matthew J; Upchurch, Gilbert R

    2005-01-01

    controls on day 7 (P = .05). Administration of the direct catalase inhibitor AT to tamoxifen-treated rats partially reversed the aneurysm inhibitory effect of tamoxifen by nearly 30% (P = .02). In contrast, catalase administration inhibited AAA formation by 44% (P = .002). The selective estrogen receptor modulator tamoxifen inhibits the development of AAAs in male rats in association with an up-regulation of catalase and inhibition of aortic wall neutrophil infiltration.

  15. VESSELS IN SOME APOCYNACEAE

    PubMed Central

    Nag, Anita; Kshetrapal, Shashikala

    1988-01-01

    In the present investigation vessels of 24 species of the family Apocynaceae have been studied. Lot of variation exist in the size and shape of vessels, number of perforation plates and intervascular thickening of walls in the taxa of Apocynaceae. PMID:22557619

  16. Investigation of radial shear in the wall-base juncture of a 1:4 scale prestressed concrete containment vessel model

    SciTech Connect

    Dameron, R.A.; Rashid, Y.R.; Luk, V.K.; Hessheimer, M.F.

    1998-04-01

    Construction of a prestressed concrete containment vessel (PCCV) model is underway as part of a cooperative containment research program at Sandia National Laboratories. The work is co-sponsored by the Nuclear Power Engineering Corporation (NUPEC) of Japan and US Nuclear Regulatory Commission (NRC). Preliminary analyses of the Sandia 1:4 Scale PCCV Model have determined axisymmetric global behavior and have estimated the potential for failure in several areas, including the wall-base juncture and near penetrations. Though the liner tearing failure mode has been emphasized, the assumption of a liner tearing failure mode is largely based on experience with reinforced concrete containments. For the PCCV, the potential for shear failure at or near the liner tearing pressure may be considerable and requires detailed investigation. This paper examines the behavior of the PCCV in the region most susceptible to a radial shear failure, the wall-basemat juncture region. Prediction of shear failure in concrete structures is a difficult goal, both experimentally and analytically. As a structure begins to deform under an applied system of forces that produce shear, other deformation modes such as bending and tension/compression begin to influence the response. Analytically, difficulties lie in characterizing the decrease in shear stiffness and shear stress and in predicting the associated transfer of stress to reinforcement as cracks become wider and more extensive. This paper examines existing methods for representing concrete shear response and existing criteria for predicting shear failure, and it discusses application of these methods and criteria to the study of the 1:4 scale PCCV.

  17. 3D rotating wall vessel and 2D cell culture of four veterinary virus pathogens: A comparison of virus yields, portions of infectious particles and virus growth curves.

    PubMed

    Malenovská, Hana

    2016-02-01

    Only very few comparative studies have been performed that evaluate general trends of virus growth under 3D in comparison with 2D cell culture conditions. The aim of this study was to investigate differences when four animal viruses are cultured in 2D and 3D. Suid herpesvirus 1 (SuHV-1), Vesicular stomatitis virus (VSIV), Bovine adenovirus (BAdV) and Bovine parainfluenza 3 virus (BPIV-3) were cultivated in 3D rotating wall vessels (RWVs) and conventional 2D cultures. The production of virus particles, the portion of infectious particles, and the infectious growth curves were compared. For all viruses, the production of virus particles (related to cell density), including the non-infectious ones, was lower in 3D than in 2D culture. The production of only infectious particles was significantly lower in BAdV and BPIV-3 in 3D cultures in relation to cell density. The two cultivation approaches resulted in significantly different virus particle-to-TCID50 ratios in three of the four viruses: lower in SuHV-1 and BPIV-3 and higher in BAdV in 3D culture. The infectious virus growth rates were not significantly different in all viruses. Although 3D RWV culture resulted in lower production of virus particles compared to 2D systems, the portion of infectious particles was higher for some viruses.

  18. Cuff for Blood-Vessel Pressure Measurements

    NASA Technical Reports Server (NTRS)

    Shimizu, M.

    1982-01-01

    Pressure within blood vessel is measured by new cufflike device without penetration of vessel. Device continuously monitors blood pressure for up to 6 months or longer without harming vessel. Is especially useful for vessels smaller than 4 or 5 millimeters in diameter. Invasive methods damage vessel wall, disturb blood flow, and cause clotting. They do not always give reliable pressure measurements over prolonged periods.

  19. Cuff for Blood-Vessel Pressure Measurements

    NASA Technical Reports Server (NTRS)

    Shimizu, M.

    1982-01-01

    Pressure within blood vessel is measured by new cufflike device without penetration of vessel. Device continuously monitors blood pressure for up to 6 months or longer without harming vessel. Is especially useful for vessels smaller than 4 or 5 millimeters in diameter. Invasive methods damage vessel wall, disturb blood flow, and cause clotting. They do not always give reliable pressure measurements over prolonged periods.

  20. Comparison of the Effect of Vessel Size Imaging and Cerebral Blood Volume Derived from Perfusion MR Imaging on Glioma Grading.

    PubMed

    Kang, H-Y; Xiao, H-L; Chen, J-H; Tan, Y; Chen, X; Xie, T; Fang, J-Q; Wang, S; Yang, Y; Zhang, W-G

    2016-01-01

    Vascular proliferation is a major criterion for grading gliomas on the basis of histology. Relative cerebral blood volume can provide pathophysiologic information about glioma grading. Vessel size imaging, in some animals, can be used to estimate the microvascular caliber of a glioma, but its clinical use remains unclear. Herein, we aimed to compare the predictive power of relative cerebral blood volume and vessel size imaging in glioma grading, with grading based on histology. Seventy patients with glioma participated in the study; 30 patients underwent MR perfusion imaging with a spin-echo sequence and vessel size imaging with a gradient-echo and spin-echo sequence successively at 24-hour intervals before surgery. We analyzed the vessel size imaging values and relative cerebral blood volume of differently graded gliomas. The microvessel parameters were histologically evaluated and compared with those on MR imaging. The cutoff values of vessel size imaging and relative cerebral blood volume obtained from receiver operating characteristic curve analyses were used to predict glioma grading in another 40 patients. Vessel size imaging values and relative cerebral blood volume were both increased in high-grade gliomas compared with low-grade gliomas (P < .01). Moreover, vessel size imaging values had higher specificity and sensitivity in differentiating high-grade from low-grade gliomas compared with relative cerebral blood volume. In addition, a significant correlation was observed between vessel size imaging values and microvessel diameters (r > 0.8, P < .05) and between relative cerebral blood volume and microvessel area (r = 0.6579, P < .05). Most important, the use of vessel size imaging cutoff values to predict glioma grading was more accurate (100%) than use of relative cerebral blood volume (85%) values. Vessel size imaging can provide more accurate information on glioma grading and may serve as an effective biomarker for the prognosis of patients with gliomas

  1. Hypoxia Inhibits De Novo Vascular Assembly of Adipose-Derived Stromal/Stem Cell Populations, but Promotes Growth of Preformed Vessels

    PubMed Central

    Hutton, Daphne L.

    2016-01-01

    Vascularization is critical for cell survival within tissue-engineered grafts. Adipose-derived stromal/stem cells (ASCs) are widely used in tissue engineering applications as they are a clinically relevant source of stem cells and endothelial progenitor cells. ASCs have previously been shown to self-assemble into pericyte-stabilized vascular networks in normoxic (20% O2) cultures. This capacity for de novo vascular assembly may accelerate graft vascularization in vivo rather than relying solely on angiogenic ingrowth. However, oxygen depletion within large cell-seeded grafts will be rapid, and it is unclear how this worsening hypoxic environment will impact the vascular assembly of the transplanted cells. The objectives of this study were to determine whether ASC-derived vessels could grow in hypoxia and to assess whether the vessel maturity (i.e., individual cells vs. preformed vessels) influenced this hypoxic response. Utilizing an in vitro vascularization model, ASCs were encapsulated within fibrin gels and cultured in vitro for up to 6 days in either normoxia (20% O2) or hypoxia (0.2% or 2% O2). In a subsequent experiment, vessels were allowed to preform in normoxia for 6 days before an additional 6 days of either normoxia or hypoxia. Viability, vessel growth, pericyte coverage, proliferation, metabolism, and angiogenic factor expression were assessed for each experimental approach. Vessel growth was dramatically inhibited in both moderate and severe hypoxia (47% and 11% total vessel length vs. normoxia, respectively), despite maintaining high cell viability and upregulating endogenous expression of vascular endothelial growth factor in hypoxia. Bromodeoxyuridine labeling indicated significantly reduced proliferation of endothelial cells in hypoxia. In contrast, when vascular networks were allowed to preform for 6 days in normoxia, vessels not only survived but also continued to grow more in hypoxia than those maintained in normoxia. These findings demonstrate

  2. Experimental Investigation of Composite Pressure Vessel Performance and Joint Stiffness for Pyramid and Inverted Pyramid Joints

    NASA Technical Reports Server (NTRS)

    Verhage, Joseph M.; Bower, Mark V.; Gilbert, Paul A. (Technical Monitor)

    2001-01-01

    The focus of this study is on the suitability in the application of classical laminate theory analysis tools for filament wound pressure vessels with adhesive laminated joints in particular: pressure vessel wall performance, joint stiffness and failure prediction. Two 18-inch diameter 12-ply filament wound pressure vessels were fabricated. One vessel was fabricated with a 24-ply pyramid laminated adhesive double strap butt joint. The second vessel was fabricated with the same number of plies in an inverted pyramid joint. Results from hydrostatic tests are presented. Experimental results were used as input to the computer programs GENLAM and Laminate, and the output compared to test. By using the axial stress resultant, the classical laminate theory results show a correlation within 1% to the experimental results in predicting the pressure vessel wall pressure performance. The prediction of joint stiffness for the two adhesive joints in the axial direction is within 1% of the experimental results. The calculated hoop direction joint stress resultant is 25% less than the measured resultant for both joint configurations. A correction factor is derived and used in the joint analysis. The correction factor is derived from the hoop stress resultant from the tank wall performance investigation. The vessel with the pyramid joint is determined to have failed in the joint area at a hydrostatic pressure 33% value below predicted failure. The vessel with the inverted pyramid joint failed in the wall acreage at a hydrostatic pressure within 10% of the actual failure pressure.

  3. Flavin-derived self-organization and chirality separation of single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Ju, Sang-Yong

    2008-07-01

    Formed by rolling up a two-dimensional sheet of one or more layer of graphite, graphene, carbon nanotubes (SWNTs) are the marvel materials of modern materials science. They are phenomenally strong and stiff, and have the unusual property of being excellent conductors of heat along the tube's axis, but good thermal insulators across it. But it is their electrical characteristics that excite the most interest. Especially, single-walled carbon nanotube (SWNTs), formed by one layer of cylindrical graphene, has better physical properties over multi-walled carbon nanotubes (MWNTs) having over two layer of graphene. Depending on the precise way they are rolled up, which is defined by ( n,m) vector, SWNTs can be made into either metals or semiconductors. So far, SWNTs can generally only be fabricated in batches that vary widely, both in the diameter of the individual tubes and in the orientation of their graphene lattice relative to the tube axis, the property known as chirality. Separating out these various conformations is a challenging, but one that must be solved if nanotubes are ever to fulfill their electrifying potential in devices. This thesis presents that flavin-based helical self-assembly can impart multi degrees of SWNTs separation (i.e., metallicity, diameter, chirality, and handedness). As opening chapters for carbon nanotube and flavin derivative, Chapter 1 provide the introduction of carbon nanotubes, especially single-walled tubes, and the current state-of-the-art nanotube separation. Also, Chapter 1 presents a variety of naturally-occurring flavin derivatives, their redox behavior, and their biological utilization as cofactors for various proteins. Motivated by chemoluminescence of flavin mononucleotide (FMN, phosphorylated form of Vitamin B2) with bacterial luciferase, Chapter 2 discuss about the synthesis and covalent attachment of flavin mononucleotide (FMN, phosphorylated form of Vitamin B2) analogue to oxidized SWNTs. Along with nine step synthesis

  4. Podoplanin is a component of extracellular vesicles that reprograms cell-derived exosomal proteins and modulates lymphatic vessel formation

    PubMed Central

    Andrés, Germán; Gopal, Shashi K.; Martín-Villar, Ester; Renart, Jaime; Simpson, Richard J.; Quintanilla, Miguel

    2016-01-01

    Podoplanin (PDPN) is a transmembrane glycoprotein that plays crucial roles in embryonic development, the immune response, and malignant progression. Here, we report that cells ectopically or endogenously expressing PDPN release extracellular vesicles (EVs) that contain PDPN mRNA and protein. PDPN incorporates into membrane shed microvesicles (MVs) and endosomal-derived exosomes (EXOs), where it was found to colocalize with the canonical EV marker CD63 by immunoelectron microscopy. We have previously found that expression of PDPN in MDCK cells induces an epithelial-mesenchymal transition (EMT). Proteomic profiling of MDCK-PDPN cells compared to control cells shows that PDPN-induced EMT is associated with upregulation of oncogenic proteins and diminished expression of tumor suppressors. Proteomic analysis of exosomes reveals that MDCK-PDPN EXOs were enriched in protein cargos involved in cell adhesion, cytoskeletal remodeling, signal transduction and, importantly, intracellular trafficking and EV biogenesis. Indeed, expression of PDPN in MDCK cells stimulated both EXO and MV production, while knockdown of endogenous PDPN in human HN5 squamous carcinoma cells reduced EXO production and inhibited tumorigenesis. EXOs released from MDCK-PDPN and control cells both stimulated in vitro angiogenesis, but only EXOs containing PDPN were shown to promote lymphatic vessel formation. This effect was mediated by PDPN on the surface of EXOs, as demonstrated by a neutralizing specific monoclonal antibody. These results contribute to our understanding of PDPN-induced EMT in association to tumor progression, and suggest an important role for PDPN in EV biogenesis and/or release and for PDPN-EXOs in modulating lymphangiogenesis. PMID:26893367

  5. Placental mesenchymal stromal cells derived from blood vessels or avascular tissues: what is the better choice to support endothelial cell function?

    PubMed

    König, Julia; Weiss, Gregor; Rossi, Daniele; Wankhammer, Karin; Reinisch, Andreas; Kinzer, Manuela; Huppertz, Berthold; Pfeiffer, Dagmar; Parolini, Ornella; Lang, Ingrid

    2015-01-01

    Mesenchymal stromal cells (MSCs) are promising tools for therapeutic revascularization of ischemic tissues and for support of vessel formation in engineered tissue constructs. Recently, we could show that avascular-derived MSCs from placental amnion release soluble factors that exhibit survival-enhancing effects on endothelial cells (ECs). We hypothesize that MSCs derived from placental blood vessels might have even more potent angiogenic effects. Therefore, we isolated and characterized MSCs from placental chorionic blood vessels (bv-MSCs) and tested their angiogenic potential in comparison to amnion-derived avascular MSCs (av-MSCs). bv-MSCs express a very similar surface marker profile compared with av-MSCs and could be differentiated toward the adipogenic and osteogenic lineages. bv-MSCs exert immunosuppressive properties on peripheral blood mononuclear cells, suggesting that they are suitable for cell transplantation settings. Conditioned medium (Cdm) from av-MSCs and bv-MSCs significantly enhanced EC viability, whereas only Cdm from bv-MSCs significantly increased EC migration and network formation (Matrigel assay). Angiogenesis array analysis of av- and bv-MSC-Cdm revealed a similar secretion pattern of angiogenic factors, including angiogenin, interleukins-6 and -8, and tissue inhibitors of matrix metalloproteinase-1 and 2. Enzyme-linked immunosorbent assay analysis showed that, in contrast to av-MSCs, bv-MSCs secreted vascular endothelial growth factor. In direct coculture with bv-MSCs, ECs showed a significantly increased formation of vessel-like structures compared with av-MSCs. With regard to therapeutic treatment, bv-MSCs and particularly their Cdm might be valuable to stimulate angiogenesis especially in ischemic tissues. av-MSCs and their Cdm could be beneficial in conditions when it is required to promote the survival and stabilization of blood vessels without the risk of unmeant angiogenesis.

  6. Simulated Microgravity Regulates Gene Transcript Profiles of 2T3 Preosteoblasts: Comparison of the Random Positioning Machine and the Rotating Wall Vessel Bioreactor

    NASA Technical Reports Server (NTRS)

    Patel, Mamta J.; Liu, Wenbin; Sykes, Michelle C.; Ward, Nancy E.; Risin, Semyon A.; Risin, Diana; Hanjoong, Jo

    2007-01-01

    Microgravity of spaceflight induces bone loss due in part to decreased bone formation by osteoblasts. We have previously examined the microgravity-induced changes in gene expression profiles in 2T3 preosteoblasts using the Random Positioning Machine (RPM) to simulate microgravity conditions. Here, we hypothesized that exposure of preosteoblasts to an independent microgravity simulator, the Rotating Wall Vessel (RWV), induces similar changes in differentiation and gene transcript profiles, resulting in a more confined list of gravi-sensitive genes that may play a role in bone formation. In comparison to static 1g controls, exposure of 2T3 cells to RWV for 3 days inhibited alkaline phosphatase activity, a marker of differentiation, and downregulated 61 genes and upregulated 45 genes by more than two-fold as shown by microarray analysis. The microarray results were confirmed with real time PCR for downregulated genes osteomodulin, bone morphogenic protein 4 (BMP4), runx2, and parathyroid hormone receptor 1. Western blot analysis validated the expression of three downregulated genes, BMP4, peroxiredoxin IV, and osteoglycin, and one upregulated gene peroxiredoxin I. Comparison of the microarrays from the RPM and the RWV studies identified 14 gravi-sensitive genes that changed in the same direction in both systems. Further comparison of our results to a published database showing gene transcript profiles of mechanically loaded mouse tibiae revealed 16 genes upregulated by the loading that were shown to be downregulated by RWV and RPM. These mechanosensitive genes identified by the comparative studies may provide novel insights into understanding the mechanisms regulating bone formation and potential targets of countermeasure against decreased bone formation both in astronauts and in general patients with musculoskeletal disorders.

  7. Use of the rotating wall vessel technology to study the effect of shear stress on growth behaviour of Pseudomonas aeruginosa PA01.

    PubMed

    Crabbé, Aurélie; De Boever, Patrick; Van Houdt, Rob; Moors, Hugo; Mergeay, Max; Cornelis, Pierre

    2008-08-01

    The biofilm phenotype of Pseudomonas aeruginosa enables this opportunistic pathogen to develop resistance to the immune system and antimicrobial agents. Pseudomonas aeruginosa biofilms are generated under varying levels of shear stress, depending on the infection site. In the lung mucus of cystic fibrosis (CF) patients, P. aeruginosa forms matrix-enclosed microcolonies which cause chronic infections representing the major cause of mortality in CF patients. The lung mucus of CF patients is probably characterized by low fluid shear as the main shear-causing factor, i.e. mucociliary clearance, is absent. In this study, the influence of fluid shear on the growth behaviour of P. aeruginosa PA01 was investigated using a low-shear suspension culture device, the rotating wall vessel (RWV). Cultivation in low shear induced a self-aggregating phenotype of P. aeruginosa PA01, resulting in the formation of biofilms in suspension similar to what has been described in CF mucus. The addition of a ceramic bead to the culture medium in the RWV created a higher-shear condition which led to the formation of surface-attached rather than suspension biofilms. In low-shear culture conditions, a significant increase of the rhl N-butanoyl-l-homoserine lactone (C(4)-HSL) directed quorum sensing (QS) system, and the psl polysaccharide synthetic locus was demonstrated using gene expression analysis. Accordingly, the low-shear condition induced a higher production of rhamnolipids, which is controlled by the C(4)-HSL QS-system and is known to play a role in CF lung pathology. These results indicate that fluid shear has an impact on the growth phenotype of P. aeruginosa which might play a role in CF lung infections caused by this bacterium.

  8. Longitudinal changes in structural abnormalities using MDCT in COPD: do the CT measurements of airway wall thickness and small pulmonary vessels change in parallel with emphysematous progression?

    PubMed Central

    Takayanagi, Shin; Kawata, Naoko; Tada, Yuji; Ikari, Jun; Matsuura, Yukiko; Matsuoka, Shin; Matsushita, Shoichiro; Yanagawa, Noriyuki; Kasahara, Yasunori; Tatsumi, Koichiro

    2017-01-01

    Background Recent advances in multidetector computed tomography (MDCT) facilitate acquiring important clinical information for managing patients with COPD. MDCT can detect the loss of lung tissue associated with emphysema as a low-attenuation area (LAA) and the thickness of airways as the wall area percentage (WA%). The percentage of small pulmonary vessels <5 mm2 (% cross-sectional area [CSA] <5) has been recently recognized as a parameter for expressing pulmonary perfusion. We aimed to analyze the longitudinal changes in structural abnormalities using these CT parameters and analyze the effect of exacerbation and smoking cessation on structural changes in COPD patients. Methods We performed pulmonary function tests (PFTs), an MDCT, and a COPD assessment test (CAT) in 58 patients with COPD at the time of their enrollment at the hospital and 2 years later. We analyzed the change in clinical parameters including CT indices and examined the effect of exacerbations and smoking cessation on the structural changes. Results The CAT score and forced expiratory volume in 1 second (FEV1) did not significantly change during the follow-up period. The parameters of emphysematous changes significantly increased. On the other hand, the WA% at the distal airways significantly decreased or tended to decrease, and the %CSA <5 slightly but significantly increased over the same period, especially in ex-smokers. The parameters of emphysematous change were greater in patients with exacerbations and continued to progress even after smoking cessation. In contrast, the WA% and %CSA <5 did not change in proportion to emphysema progression. Conclusion The WA% at the distal bronchi and the %CSA <5 did not change in parallel with parameters of LAA over the same period. We propose that airway disease and vascular remodeling may be reversible to some extent by smoking cessation and appropriate treatment. Optimal management may have a greater effect on pulmonary vascularity and airway disease

  9. Estimation of PSD Shifts for High-Resolution Metrology of Thickness Micro-Changes with Possible Applications in Vessel Walls and Biological Membrane Characterization

    PubMed Central

    Ramos, Antonio; Bazán, Ivonne; Negreira, Carlos; Brum, Javier; Gómez, Tomás; Calás, Héctor; Ruiz, Abelardo; de la Rosa, José Manuel

    2012-01-01

    Achieving accurate measurements of inflammation levels in tissues or thickness changes in biological membranes (e.g., amniotic sac, parietal pleura) and thin biological walls (e.g., blood vessels) from outside the human body, is a promising research line in the medical area. It would provide a technical basis to study the options for early diagnosis of some serious diseases such as hypertension, atherosclerosis or tuberculosis. Nevertheless, achieving the aim of non-invasive measurement of those scarcely-accessible parameters on patient internal tissues, currently presents many difficulties. The use of high-frequency ultrasonic transducer systems appears to offer a possible solution. Previous studies using conventional ultrasonic imaging have shown this, but the spatial resolution was not sufficient so as to permit a thickness evaluation with clinical significance, which requires an accuracy of a few microns. In this paper a broadband ultrasonic technique, that was recently developed by the authors to address other non-invasive medical detection problems (by integrating a piezoelectric transducer into a spectral measuring system), is extended to our new objective; the aim is its application to the thickness measurement of sub-millimeter membranes or layers made of materials similar to some biological tissues (phantoms). The modeling and design rules of such a transducer system are described, and various methods of estimating overtones location in the power spectral density (PSD) are quantitatively assessed with transducer signals acquired using piezoelectric systems and also generated from a multi-echo model. Their effects on the potential resolution of the proposed thickness measuring tool, and their capability to provide accuracies around the micron are studied in detail. Comparisons are made with typical tools for extracting spatial parameters in laminar samples from echo-waveforms acquired with ultrasonic transducers. Results of this advanced measurement

  10. Intracranial Plaque Characterization in Patients with Acute Ischemic Stroke Using Pre- and Post-Contrast Three-Dimensional Magnetic Resonance Vessel Wall Imaging.

    PubMed

    Natori, Tatsunori; Sasaki, Makoto; Miyoshi, Mitsuharu; Ito, Kohei; Ohba, Hideki; Miyazawa, Haruna; Narumi, Shinsuke; Kabasawa, Hiroyuki; Harada, Taisuke; Terayama, Yasuo

    2016-06-01

    Magnetic resonance vessel wall imaging (VWI) techniques have been developed to assess atherosclerotic plaques in intracranial arteries, which are a cardinal cause of ischemic stroke. However, the clinical roles of plaque-related vulnerability and inflammation remain unclear. Hence, we evaluated plaque characteristics using VWI of the proximal middle cerebral artery (M1) in patients with acute ischemic stroke. We prospectively examined 30 consecutive patients with acute noncardioembolic stroke in the M1 territory using pre-/postcontrast T1-weighted (T1W) three-dimensional (3D) VWI with a 3-Tesla scanner. The contrast ratio (CR) and contrast enhancement of the plaques were measured bilaterally at M1. Plaques were identified in the bilateral M1s of all patients, and no substantial stenosis existed. The M1 plaque CRs ipsilateral to the infarct (46.7%-67.9%) were significantly higher than the plaque CRs on the contralateral side (34.3%-69.4%), particularly in patients with lacunar infarcts (P <.01). In contrast, the occurrence of plaque enhancement was not different between the ipsilateral (20.0%) and contralateral (16.7%) sides. Further, the CRs in the nonlacunar group were significantly higher than the CRs in the lacunar group (P <.05), whereas enhanced plaques tended to be more frequent in the nonlacunar group, but this difference was not significant (P = .09). T1W 3D-VWI revealed that the signal intensity of M1 plaques was significantly higher in the affected side and in nonlacunar-type infarcts of patients with acute stroke, suggesting that unstable plaques in the M1 can cause stroke events presumably due to atherothrombotic mechanisms. Copyright © 2016 National Stroke Association. Published by Elsevier Inc. All rights reserved.

  11. Cross-linking density alters early metabolic activities in chondrocytes encapsulated in poly(ethylene glycol) hydrogels and cultured in the rotating wall vessel.

    PubMed

    Villanueva, Idalis; Klement, Brenda J; von Deutsch, Daniel; Bryant, Stephanie J

    2009-03-01

    In designing a tissue engineering strategy for cartilage repair, selection of both the bioreactor, and scaffold is important to the development of a mechanically functional tissue. The hydrodynamic environment associated with many bioreactors enhances nutrient transport, but also introduces fluid shear stress, which may influence cellular response. This study examined the combined effects of hydrogel cross-linking and the hydrodynamic environment on early chondrocyte response. Specifically, chondrocytes were encapsulated in poly(ethylene glycol) (PEG) hydrogels having two different cross-linked structures, corresponding to a low and high cross-linking density. Both cross-linked gels yielded high water contents (92% and 79%, respectively) and mesh sizes of 150 and 60 A respectively. Cell-laden PEG hydrogels were cultured in rotating wall vessels (RWV) or under static cultures for up to 5 days. Rotating cultures yielded low fluid shear stresses (< or = 0.11 Pa) at the hydrogel periphery indicating a laminar hydrodynamic environment. Chondrocyte response was measured through total DNA content, total nitric oxide (NO) production, and matrix deposition for glycosaminoglycans (GAG). In static cultures, gel cross-linking had no effect on DNA content, NO production, or GAG production; although GAG production increased with culture time for both cross-linked gels. In rotating cultures, DNA content increased, NO production decreased, and overall GAG production decreased when compared to static controls for the low cross-linked gels. For the high cross-linked gels, the hydrodynamic environment had no effect on DNA content, but exhibited similar results to the low cross-linked gel for NO production, and matrix production. Our findings demonstrated that at early culture times, when there is limited matrix production, the hydrodynamic environment dramatically influences cell response in a manner dependent on the gel cross-linking, which may impact long-term tissue development.

  12. Airway Wall Area Derived from 3-Dimensional Computed Tomography Analysis Differs among Lung Lobes in Male Smokers

    PubMed Central

    Tho, Nguyen Van; Trang, Le Thi Huyen; Murakami, Yoshitaka; Ogawa, Emiko; Ryujin, Yasushi; Kanda, Rie; Nakagawa, Hiroaki; Goto, Kenichi; Fukunaga, Kentaro; Higami, Yuichi; Seto, Ruriko; Nagao, Taishi; Oguma, Tetsuya; Yamaguchi, Masafumi; Lan, Le Thi Tuyet; Nakano, Yasutaka

    2014-01-01

    Background It is time-consuming to obtain the square root of airway wall area of the hypothetical airway with an internal perimeter of 10 mm (√Aaw at Pi10), a comparable index of airway dimensions in chronic obstructive pulmonary disease (COPD), from all airways of the whole lungs using 3-dimensional computed tomography (CT) analysis. We hypothesized that √Aaw at Pi10 differs among the five lung lobes and √Aaw at Pi10 derived from one certain lung lobe has a high level of agreement with that derived from the whole lungs in smokers. Methods Pulmonary function tests and chest volumetric CTs were performed in 157 male smokers (102 COPD, 55 non-COPD). All visible bronchial segments from the 3rd to 5th generations were segmented and measured using commercially available 3-dimensional CT analysis software. √Aaw at Pi10 of each lung lobe was estimated from all measurable bronchial segments of that lobe. Results Using a mixed-effects model, √Aaw at Pi10 differed significantly among the five lung lobes (R2 = 0.78, P<0.0001). The Bland-Altman plots show that √Aaw at Pi10 derived from the right or left upper lobe had a high level of agreement with that derived from the whole lungs, while √Aaw at Pi10 derived from the right or left lower lobe did not. Conclusion In male smokers, CT-derived airway wall area differs among the five lung lobes, and airway wall area derived from the right or left upper lobe is representative of the whole lungs. PMID:24865661

  13. 9-Lipoxygenase-Derived Oxylipins Activate Brassinosteroid Signaling to Promote Cell Wall-Based Defense and Limit Pathogen Infection1

    PubMed Central

    Marcos, Ruth; Izquierdo, Yovanny; Vellosillo, Tamara; Kulasekaran, Satish; Cascón, Tomás; Hamberg, Mats; Castresana, Carmen

    2015-01-01

    The oxylipins, a large family of oxygenated lipid derivatives, regulate plant development and immunity. Two members of the 9-lipoxygenase (9-LOX) oxylipin pathway, 9-hydroxyoctadecatrienoic acid and 9-ketooctadecatrienoic acid, control root development and plant defense. Studies in Arabidopsis (Arabidopsis thaliana) using a series of 9-hydroxyoctadecatrienoic acid- and 9-ketooctadecatrienoic acid-insensitive nonresponding to oxylipins (noxy) mutants showed the importance of the cell wall as a 9-LOX-induced defense component and the participation of NOXY proteins in signaling cell wall damage. Here, we examined 9-LOX signaling using the mutants lox1lox5, which lacks 9-LOX activity, and noxy2-2, which shows oxylipin insensitivity and mitochondrial dysfunction. Mutants in brassinosteroids (BRs), a class of plant hormones necessary for normal plant growth and the control of cell wall integrity, were also analyzed. Several lines of evidence indicated that 9-LOX-derived oxylipins induce BR synthesis and signaling to activate cell wall-based responses such as callose deposition and that constitutive activation of BR signaling in bri1-EMS-suppressor 1-D (bes1-D) plants enhances this response. We found that constitutive BR signaling in bes1-D and brassinolide-resistant 1-1D (bzr1-1D) mutants conferred resistance to Pseudomonas syringae. bes1-D and bzr1-1D showed increased resistance to Golovinomyces cichoracearum, an obligate biotrophic fungus that penetrates the cell wall for successful infection, whereas susceptibility was enhanced in lox1lox5 and noxy2-2. Our results indicate a sequential action of 9-LOX and BR signaling in activating cell wall-based defense, and this response prevents pathogen infection. These results show interaction between the 9-LOX and BR pathways and help to clarify their role in modulating plant defense. PMID:26417008

  14. The transport of nanoparticles in blood vessels: the effect of vessel permeability and blood rheology.

    PubMed

    Gentile, Francesco; Ferrari, Mauro; Decuzzi, Paolo

    2008-02-01

    The longitudinal transport of nanoparticles in blood vessels has been analyzed with blood described as a Casson fluid. Starting from the celebrated Taylor and Aris theory, an explicit expression has been derived for the effective longitudinal diffusion (Deff) depending non-linearly on the rheological parameter xi(c), the ratio between the plug and the vessel radii; and on the permeability parameters pi and omega, related to the hydraulic conductivity and pressure drop across the vessel wall, respectively. An increase of xi(c) or pi has the effect of reducing Deff, and thus both the rheology of blood and the permeability of the vessels may constitute a physiological barrier to the intravascular delivery of nanoparticles.

  15. Curved and conformal high-pressure vessel

    SciTech Connect

    Croteau, Paul F.; Kuczek, Andrzej E.; Zhao, Wenping

    2016-10-25

    A high-pressure vessel is provided. The high-pressure vessel may comprise a first chamber defined at least partially by a first wall, and a second chamber defined at least partially by the first wall. The first chamber and the second chamber may form a curved contour of the high-pressure vessel. A modular tank assembly is also provided, and may comprise a first mid tube having a convex geometry. The first mid tube may be defined by a first inner wall, a curved wall extending from the first inner wall, and a second inner wall extending from the curved wall. The first inner wall may be disposed at an angle relative to the second inner wall. The first mid tube may further be defined by a short curved wall opposite the curved wall and extending from the second inner wall to the first inner wall.

  16. Growth of Intracranial Aneurysms Arised from Curved Vessels under the Influence of Elevated Wall Shear Stress ─ A Computer Simulation Study

    NASA Astrophysics Data System (ADS)

    Feng, Yixiang; Wada, Shigeo; Tsubota, Ken-Ichi; Yamaguchi, Takami

    Recent studies have suggested that long standing elevated wall shear stress might degenerate the arterial wall and be involved in the pathogenesis of intracranial aneurysm formation and development. The present study focuses on the interplay between the hemodynamic stresses, arterial wall degeneration and deformation. By constructing a computational model and examining the hypotheses that govern the rules to grow an intracranial aneurysm, we simulate the formation and development of intracranial aneurysms. The high wall shear stress is found to propagate towards the proximal and distal end of the formed aneurysm, which becomes the key factor for the expansion of wall degeneration and aneurysm progression. The development of aneurysm is influenced by the wall shear stress threshold, the Reynolds number and the rate of wall degeneration. Our preliminary results indicate that computer simulation can be used in the study of aneurysm mechanics and yields new insight into the mechanism of aneurysm pathophysiology.

  17. Platelet-Derived Growth Factor-B Normalizes Micromorphology and Vessel Function in Vascular Endothelial Growth Factor-A-Induced Squamous Cell Carcinomas

    PubMed Central

    Lederle, Wiltrud; Linde, Nina; Heusel, Julia; Bzyl, Jessica; Woenne, Eva C.; Zwick, Stefan; Skobe, Mihaela; Kiessling, Fabian; Fusenig, Norbert E.; Mueller, Margareta M.

    2010-01-01

    Vascular endothelial growth factor (VEGF), which is a key regulator of angiogenesis, often induces formation of immature vessels with increased permeability and reduced vessel functionality. Here, we demonstrate that de novo expression of murine (m)VEGF-164 induces malignant and invasive tumor growth of HaCaT keratinocytes. However, the mVEGF-164-induced tumors are ulcerated with a disorganized epithelium that is interrupted by lacunae with limited basement membrane and endothelial cell coverage. Vessel maturation is strongly impaired. Tumor and vessel micromorphology are markedly improved by the combined expression of human platelet-derived growth factor (hPDGF)-B and mVEGF-164. Although tumor size and malignancy are comparable with either mVEGF-164 alone or combined human PDGF-B and mVEGF-164 expression, combined hPDGF-B and mVEGF-164 expression leads to a more solid and compact tumor tissue with a mature functional tumor vasculature and a higher microvessel density, as demonstrated histologically and by dynamic contrast-enhanced magnetic resonance imaging. Treatment of the hPDGF-B- and mVEGF-164-expressing tumors with imatinib mesylate to block PDGF-B signaling reverses this effect. In addition, tumor cell invasion of mVEGF-164 transfectants and mVEGF-164 plus hPDGF-B transfectants in vivo is associated with a marked induction of tumor-derived matrix metalloproteinase-1 and stromal matrix metalloproteinase-9 and -13, as was confirmed in three-dimensional organotypic co-cultures with fibroblasts in vitro. These data clearly demonstrate the need for a concerted action of different growth factors in the establishment of solid tumors with functional vasculature and emphasize the need for a multifactorial therapy. PMID:20042679

  18. 33 CFR 401.3 - Maximum vessel dimensions.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... anything on the vessel extends more than 35.5 m above water level. (c) No vessel shall transit if any part... superstructure when alongside a lock wall shall extend beyond the limits of the lock wall, as illustrated in...

  19. 33 CFR 401.3 - Maximum vessel dimensions.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... anything on the vessel extends more than 35.5 m above water level. (c) No vessel shall transit if any part... superstructure when alongside a lock wall shall extend beyond the limits of the lock wall, as illustrated in...

  20. 33 CFR 401.3 - Maximum vessel dimensions.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... anything on the vessel extends more than 35.5 m above water level. (c) No vessel shall transit if any part... superstructure when alongside a lock wall shall extend beyond the limits of the lock wall, as illustrated in...

  1. Dissolver vessel bottom assembly

    DOEpatents

    Kilian, Douglas C.

    1976-01-01

    An improved bottom assembly is provided for a nuclear reactor fuel reprocessing dissolver vessel wherein fuel elements are dissolved as the initial step in recovering fissile material from spent fuel rods. A shock-absorbing crash plate with a convex upper surface is disposed at the bottom of the dissolver vessel so as to provide an annular space between the crash plate and the dissolver vessel wall. A sparging ring is disposed within the annular space to enable a fluid discharged from the sparging ring to agitate the solids which deposit on the bottom of the dissolver vessel and accumulate in the annular space. An inlet tangential to the annular space permits a fluid pumped into the annular space through the inlet to flush these solids from the dissolver vessel through tangential outlets oppositely facing the inlet. The sparging ring is protected against damage from the impact of fuel elements being charged to the dissolver vessel by making the crash plate of such a diameter that the width of the annular space between the crash plate and the vessel wall is less than the diameter of the fuel elements.

  2. 46 CFR 309.8 - Vessel data forms.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ..., Vessel Data. Copies of this form may be obtained from either the American War Risk Agency, 14 Wall Street... 400 Seventh Street SW., Washington, DC 20590. (b) Modification to vessels. Revised vessel data shall...

  3. 46 CFR 309.8 - Vessel data forms.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ..., Vessel Data. Copies of this form may be obtained from either the American War Risk Agency, 14 Wall Street... 400 Seventh Street SW., Washington, DC 20590. (b) Modification to vessels. Revised vessel data...

  4. 46 CFR 309.8 - Vessel data forms.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ..., Vessel Data. Copies of this form may be obtained from either the American War Risk Agency, 14 Wall Street... 400 Seventh Street SW., Washington, DC 20590. (b) Modification to vessels. Revised vessel data...

  5. 46 CFR 309.8 - Vessel data forms.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ..., Vessel Data. Copies of this form may be obtained from either the American War Risk Agency, 14 Wall Street... 400 Seventh Street SW., Washington, DC 20590. (b) Modification to vessels. Revised vessel data...

  6. 46 CFR 309.8 - Vessel data forms.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ..., Vessel Data. Copies of this form may be obtained from either the American War Risk Agency, 14 Wall Street... 400 Seventh Street SW., Washington, DC 20590. (b) Modification to vessels. Revised vessel data...

  7. Specific Accumulation of Tumor-Derived Adhesion Factor in Tumor Blood Vessels and in Capillary Tube-Like Structures of Cultured Vascular Endothelial Cells

    NASA Astrophysics Data System (ADS)

    Akaogi, Kotaro; Okabe, Yukie; Sato, Junji; Nagashima, Yoji; Yasumitsu, Hidetaro; Sugahara, Kazuyuki; Miyazaki, Kaoru

    1996-08-01

    Tumor-derived adhesion factor (TAF) was previously identified as a cell adhesion molecule secreted by human bladder carcinoma cell line EJ-1. To elucidate the physiological function of TAF, we examined its distribution in human normal and tumor tissues. Immunochemical staining with an anti-TAF monoclonal antibody showed that TAF was specifically accumulated in small blood vessels and capillaries within and adjacent to tumor nests, but not in those in normal tissues. Tumor blood vessel-specific staining of TAF was observed in various human cancers, such as esophagus, brain, lung, and stomach cancers. Double immunofluorescent staining showed apparent colocalization of TAF and type IV collagen in the vascular basement membrane. In vitro experiments demonstrated that TAF preferentially bound to type IV collagen among various extracellular matrix components tested. In cell culture experiments, TAF promoted adhesion of human umbilical vein endothelial cells to type IV collagen substrate and induced their morphological change. Furthermore, when the endothelial cells were induced to form capillary tube-like structures by type I collagen, TAF and type IV collagen were exclusively detected on the tubular structures. The capillary tube formation in vitro was prevented by heparin, which inhibited the binding of TAF to the endothelial cells. These results strongly suggest that TAF contributes to the organization of new capillary vessels in tumor tissues by modulating the interaction of endothelial cells with type IV collagen.

  8. Cellulose derivatives as excellent dispersants for single-wall carbon nanotubes as demonstrated by absorption and photoluminescence spectroscopy

    NASA Astrophysics Data System (ADS)

    Minami, Nobutsugu; Kim, Yeji; Miyashita, Kanae; Kazaoui, Said; Nalini, Balakrishnan

    2006-02-01

    Sodium carboxymethylcellulose, an etherified derivative of cellulose, has been found to realize stable aqueous dispersion of single-wall carbon nanotubes (SWNTs) that is twenty times more concentrated than when a surfactant is used under the same condition. The dispersion as well as thin films prepared from it exhibits well-resolved near-infrared photoluminescence peaks originating from band-gap transitions in semiconducting SWNTs, a sign of isolated individual tubes. Mechanical stretching of the film strongly aligns the tubes, as demonstrated by considerable dichroism in their absorption spectra. Possessing high optical quality and uniformity, these densely dispersed SWNT films are expected to serve as an important platform for SWNTs' optical, electrical, and optoelectronic applications, especially because cellulose derivatives are cheap, mass-produced, safe, water-processable, and environmentally benign.

  9. A Real-Time Monitoring System to Assess the Platelet Aggregatory Capacity of Components of a Tissue-Engineered Blood Vessel Wall.

    PubMed

    Musa, Faiza Idris; Harper, Alan G S; Yang, Ying

    2016-07-01

    Native blood vessels contain both an antiaggregatory intimal layer, which prevents platelet activation in the intact vessel, and a proaggregatory medial layer, which stimulates platelet aggregation upon vascular damage. Yet, current techniques for assessing the functional properties of tissue-engineered blood vessels may not be able to assess the relative effectiveness of both these pro- and antiaggregatory properties of the vessel construct. In this study, we present a novel technique for quantitatively assessing the pro- and antiaggregatory properties of different three-dimensional blood vessel constructs made using a layered fabrication method. This technique utilizes real-time measurements of cytosolic Ca(2+) signaling to assess platelet activation in fluorescently labeled human platelet suspensions using fluorescence spectrofluorimetry, while also permitting examination of thrombus formation upon the surface of the construct using fluorescent imaging of DiOC6-labeled platelets. Experiments using this method demonstrated that type I collagen hydrogels, commonly used as scaffolds for vascular tissue engineering, were unable to support significant platelet activation, while type I and III neo-collagen secreted from human coronary artery smooth muscle cells cultured within these hydrogels as the medial layer were able to support thrombus formation. The incorporation of an intimal layer consisting of human umbilical vein endothelial cells on top of the medial layer inhibited platelet activation and aggregation. These data demonstrate that the methodology presented here is able to quantitatively compare the capacity of different constructs to trigger or prevent platelet activation. As such, this technique may provide a useful tool for standardizing the assessment of the functional properties of tissue-engineered blood vessel constructs developed using different culturing techniques.

  10. The pro-inflammatory signalling regulator Stat4 promotes vasculogenesis of great vessels derived from endothelial precursors

    PubMed Central

    Meng, Zhao-Zheng; Liu, Wei; Xia, Yu; Yin, Hui-Min; Zhang, Chi-Yuan; Su, Dan; Yan, Li-Feng; Gu, Ai-Hua; Zhou, Yong

    2017-01-01

    Vasculogenic defects of great vessels (GVs) are a major cause of congenital cardiovascular diseases. However, genetic regulators of endothelial precursors in GV vasculogenesis remain largely unknown. Here we show that Stat4, a transcription factor known for its regulatory role of pro-inflammatory signalling, promotes GV vasculogenesis in zebrafish. We find stat4 transcripts highly enriched in nkx2.5+ endothelial precursors in the pharynx and demonstrate that genetic ablation of stat4 causes stenosis of pharyngeal arch arteries (PAAs) by suppressing PAAs 3–6 angioblast development. We further show that stat4 is a downstream target of nkx2.5 and that it autonomously promotes proliferation of endothelial precursors of the mesoderm. Mechanistically, stat4 regulates the emerging PAA angioblasts by inhibiting the expression of hdac3 and counteracting the effect of stat1a. Altogether, our study establishes a role for Stat4 in zebrafish great vessel development, and suggests that Stat4 may serve as a therapeutic target for GV defects. PMID:28256502

  11. Optical properties of fluorescent zigzag graphene quantum dots derived from multi-walled carbon nanotubes

    SciTech Connect

    Chen, Wei; Li, Fushan Wu, Chaoxing; Guo, Tailiang

    2014-02-10

    Graphene quantum dots (GQDs), which are edge-bound nanometer-size graphene pieces, have fascinating electronic and optical properties due to their quantum confinement and edge effect. In this paper, GQDs were synthesized by using acid treatment and chemical exfoliation of multi-walled carbon nanotubes (MWCNTs). The structure of the GQDs was investigated by transmission electron microscope. The GQDs have a uniform size distribution, zigzag edge structure and two-dimensional morphology. The results indicated that the GQDs have bright blue emission upon UV excitation. The highly fluorescent GQDs exhibited high water solubility and good stability. It is shown that the acid treatment of MWCNTs leads to the formation of the functional group in zigzag sites, which results in the pH-dependent fluorescence of the GQDs.

  12. Widespread Myocardial Delivery of Heart-Derived Stem Cells by Nonocclusive Triple-Vessel Intracoronary Infusion in Porcine Ischemic Cardiomyopathy: Superior Attenuation of Adverse Remodeling Documented by Magnetic Resonance Imaging and Histology

    PubMed Central

    Tseliou, Eleni; Kanazawa, Hideaki; Dawkins, James; Gallet, Romain; Kreke, Michelle; Smith, Rachel; Middleton, Ryan; Valle, Jackelyn; Marbán, Linda; Kar, Saibal; Makkar, Rajendra; Marbán, Eduardo

    2016-01-01

    Single-vessel, intracoronary infusion of stem cells under stop-flow conditions has proven safe but achieves only limited myocardial coverage. Continuous flow intracoronary delivery to one or more coronary vessels may achieve broader coverage for treating cardiomyopathy, but has not been investigated. Using nonocclusive coronary guiding catheters, we infused allogeneic cardiosphere-derived cells (CDCs) either in a single vessel or sequentially in all three coronary arteries in porcine ischemic cardiomyopathy and used magnetic resonance imaging (MRI) to assess structural and physiological outcomes. Vehicle-infused animals served as controls. Single-vessel stop-flow and continuous-flow intracoronary infusion revealed equivalent effects on scar size and function. Sequential infusion into each of the three major coronary vessels under stop-flow or continuous-flow conditions revealed equal efficacy, but less elevation of necrotic biomarkers with continuous-flow delivery. In addition, multi-vessel delivery resulted in enhanced global and regional tissue function compared to a triple-vessel placebo-treated group. The functional benefits after global cell infusion were accompanied histologically by minimal inflammatory cellular infiltration, attenuated regional fibrosis and enhanced vessel density in the heart. Sequential multi-vessel non-occlusive delivery of CDCs is safe and provides enhanced preservation of left ventricular function and structure. The current findings provide preclinical validation of the delivery method currently undergoing clinical testing in the Dilated cardiomYopathy iNtervention With Allogeneic MyocardIally-regenerative Cells (DYNAMIC) trial of CDCs in heart failure patients. PMID:26784932

  13. An in vivo pilot study of a microporous thin film nitinol-covered stent to assess the effect of porosity and pore geometry on device interaction with the vessel wall.

    PubMed

    Chun, Youngjae; Kealey, Colin P; Levi, Daniel S; Rigberg, David A; Chen, Yanfei; Tillman, Bryan W; Mohanchandra, K P; Shayan, Mahdis; Carman, Gregory P

    2017-03-01

    Sputter-deposited thin film nitinol constructs with various micropatterns were fabricated to evaluate their effect on the vessel wall in vivo when used as a covering for commercially available stents. Thin film nitinol constructs were used to cover stents and deployed in non-diseased swine arteries. Swine were sacrificed after approximately four weeks and the thin film nitinol-covered stents were removed for histopathologic evaluation. Histopathology revealed differences in neointimal thickness that correlated with the thin film nitinol micropattern. Devices covered with thin film nitinol with a lateral × vertical length = 20 × 40 µm diamond pattern had minimal neointimal growth with well-organized cell architecture and little evidence of ongoing inflammation. Devices covered with thin film nitinol with smaller fenestrations exhibited a relatively thick neointimal layer with inflammation and larger fenestrations showed migration of inflammatory and smooth muscle cells through the micro fenestrations. This "proof-of-concept" study suggests that there may be an ideal thin film nitinol porosity and pore geometry to encourage endothelialization and incorporation of the device into the vessel wall. Future work will be needed to determine the optimal pore size and geometry to minimize neointimal proliferation and in-stent stenosis.

  14. Electronic properties of Cs-intercalated single-walled carbon nanotubes derived from nuclear magnetic resonance

    NASA Astrophysics Data System (ADS)

    Abou-Hamad, E.; Goze-Bac, C.; Nitze, F.; Schmid, M.; Aznar, R.; Mehring, M.; Wågberg, T.

    2011-05-01

    We report on the electronic properties of Cs-intercalated single-walled carbon nanotubes (SWNTs). A detailed analysis of the 13C and 133Cs nuclear magnetic resonance (NMR) spectra reveals an increased metallization of the pristine SWNTs under Cs intercalation. The 'metallization' of CsxC materials where x=0-0.144 is evidenced from the increased local electronic density of states (DOS) n(EF) at the Fermi level of the SWNTs as determined from spin-lattice relaxation measurements. In particular, there are two distinct electronic phases called α and β and the transition between these occurs around x=0.05. The electronic DOS at the Fermi level increases monotonically at low intercalation levels x<0.05 (α-phase), whereas it reaches a plateau in the range 0.05<=x<=0.143 at high intercalation levels (β-phase). The new β-phase is accompanied by a hybridization of Cs(6s) orbitals with C(sp2) orbitals of the SWNTs. In both phases, two types of metallic nanotubes are found with a low and a high local n(EF), corresponding to different local electronic band structures of the SWNTs.

  15. Intracoronary autologous bone marrow-derived mononuclear cell transplantation improves coronary collateral vessel formation and recruitment capacity in patients with ischemic cardiomyopathy: a combined hemodynamic and scintigraphic approach.

    PubMed

    Tayyareci, Yelda; Sezer, Murat; Umman, Berrin; Besisik, Sevgi; Mudun, Ayse; Sanli, Yasemin; Oncul, Aytac; Gurses, Nuray; Sargin, Deniz; Meric, Mehmet; Nisanci, Yilmaz

    2008-01-01

    This study investigated the effects of intracoronary autologous bone marrow-derived mononuclear cell (BMC) transplantation on coronary microcirculation. Fifteen patients with ischemic cardiomyopathy were treated by intracoronary infusion of BMCs via the patent infarct-related artery. The thermodilution-derived coronary flow reserve, index of microvascular resistance, pressure-derived collateral flow index, and coronary wedge pressure were measured at baseline and at 6 months. Successive balloon inflations during BMC transplantation were performed to observe the recruitment in pressure-derived collateral flow index and coronary wedge pressure, and the percentage changes between baseline and 6 months were calculated. The mean (SD) coronary flow reserve increased from 1.3 (0.4) to 2.1 (0.5), and the mean (SD) index of microvascular resistance decreased from 44.9 (24.4) to 21.2 (14.1) (P = .001 for both). The mean (SD) improvement in pressure-derived collateral flow index (from 0.14 [0.05] to 0.22 [0.08]) was also statistically significant (P = .001). Similarly, the percentage improvements in pressure-derived collateral flow index and coronary wedge pressure were statistically significant (P = .01 for both). The percentage improvement in perfusion assessed by single-photon emission computed tomography strongly correlated with the percentage changes in pressure-derived collateral flow index (r = 0.88, P = .001) and coronary wedge pressure (r = 0.69, P = .01). These results demonstrate for the first time (to our knowledge) that intracoronary autologous BMC transplantation improves coronary collateral vessel formation and recruitment capacity in human subjects.

  16. Efficacy of single-component MTV to measure turbulent wall-flow velocity derivative profiles at high resolution

    NASA Astrophysics Data System (ADS)

    Elsnab, John R.; Monty, Jason P.; White, Christopher M.; Koochesfahani, Manoochehr M.; Klewicki, Joseph C.

    2017-09-01

    Physical interpretations and especially analytical considerations benefit from the ability to accurately estimate derivatives of experimentally measured statistical profiles. Toward this aim, experiments were conducted to investigate the efficacy of single-component molecular tagging velocimetry (1c-MTV) to measure mean velocity profiles that can be differentiated multiple times. Critical effects here pertain to finite measurement uncertainty in the presence of high spatial resolution. Measurements acquired in fully developed turbulent channel flow over a friction Reynolds number range from 390 to 1800 are used to investigate these issues. Each measured profile contains about 880 equally spaced data points that span from near the edge of the viscous sublayer to the channel centreline. As a result of the high spatial resolution, even very small levels of uncertainty in the data adversely affect the capacity to produce smooth velocity derivative profiles. It is demonstrated that the present 1c-MTV measurements can be differentiated twice, with the resulting profile remaining smooth and accurate. The experimental mean velocity profiles and their wall-normal derivatives up to second order are shown to convincingly agree with existing DNS data, including the apparent variations with Reynolds number.

  17. Determining the syringyl/guaiacyl lignin ratio in the vessel and fiber cell walls of transgenic Populus plants

    SciTech Connect

    Tolbert, Allison K.; Ma, Tao; Kalluri, Udaya C.; Ragauskas, Arthur J.

    2016-06-20

    Observation of the spatial lignin distribution throughout the plant cell wall provides insight into the physicochemical characteristics of lignocellulosic biomass. The distribution of syringyl (S) and guaiacyl (G) lignin in cell walls of a genetically modified Populus deltoides and its corresponding empty vector control were analyzed with time-of-flight secondary ion mass spectrometry (ToF-SIMS) and then mapped to determine the S/G lignin ratio of the sample surface and specific regions of interest (ROIs). The surface characterizations of transgenic cross-sections within 1 cm vertical distance of each other on the stem possess similar S/G lignin ratios. Furthermore, the analysis of the ROIs determined that there was a 50% decrease in the S/G lignin ratio of the transgenic xylem fiber cell walls.

  18. Determining the syringyl/guaiacyl lignin ratio in the vessel and fiber cell walls of transgenic Populus plants

    SciTech Connect

    Tolbert, Allison K.; Ma, Tao; Kalluri, Udaya C.; Ragauskas, Arthur J.

    2016-06-20

    Observation of the spatial lignin distribution throughout the plant cell wall provides insight into the physicochemical characteristics of lignocellulosic biomass. The distribution of syringyl (S) and guaiacyl (G) lignin in cell walls of a genetically modified Populus deltoides and its corresponding empty vector control were analyzed with time-of-flight secondary ion mass spectrometry (ToF-SIMS) and then mapped to determine the S/G lignin ratio of the sample surface and specific regions of interest (ROIs). The surface characterizations of transgenic cross-sections within 1 cm vertical distance of each other on the stem possess similar S/G lignin ratios. Furthermore, the analysis of the ROIs determined that there was a 50% decrease in the S/G lignin ratio of the transgenic xylem fiber cell walls.

  19. Immunohistochemical evidence that culture in the high aspect rotating vessel can up-regulate hormone expression in growth dedifferentiated PHHI-derived islet cells.

    PubMed

    Webb, M'Balu A; Platton, Sharon L; Dennison, Ashley R; James, Roger F L

    2007-01-01

    Islet cells derived from patients with persistent hyperinsulinemic hypoglycemia of infancy (PHHI) have the ability to grow readily in simple culture media. However, as with primary islets and cell lines, they lose hormone expression upon growth. In this study, we have investigated the role of three-dimensional cell-to-cell contact in the reinitiation of hormone expression in growth dedifferentiated PHHI-derived cells. Two main methods of cell aggregation were studied; the promotion of pseudoislets through petri dish culture and the creation of cell aggregates in the microgravity environment of the high aspect ratio vessel (HARV). Immunohistochemical analysis and ELISA assay showed that petri dish culture did not re-establish endocrine expression in any of the five cultures tested. However, through HARV technology, we have demonstrated that it is possible to reactivate insulin, glucagon, somatostatin, and GAD expression in PHHI-derived cells that had previously stopped expressing these markers. These results indicate that the unique environment of the HARV can be conducive to the upregulation of endocrine expression of islet-derived cells and optimization of culture conditions may prove useful in the sphere of beta cell proliferation.

  20. Use of wastes derived from earthquakes for the production of concrete masonry partition wall blocks

    SciTech Connect

    Xiao Zhao; Ling, Tung-Chai; Kou, Shi-Cong; Wang Qingyuan; Poon, Chi-Sun

    2011-08-15

    Highlights: > Solved the scientific and technological challenges impeding use of waste rubble derived from earthquake, by providing an alternative solution of recycling the waste in moulded concrete block products. > Significant requirements for optimum integration on the utilization of the waste aggregates in the production of concrete blocks are investigated. > A thorough understanding of the mechanical properties of concrete blocks made with waste derived from earthquake is reported. - Abstract: Utilization of construction and demolition (C and D) wastes as recycled aggregates in the production of concrete and concrete products have attracted much attention in recent years. However, the presence of large quantities of crushed clay brick in some the C and D waste streams (e.g. waste derived collapsed masonry buildings after an earthquake) renders the recycled aggregates unsuitable for high grade use. One possibility is to make use of the low grade recycled aggregates for concrete block production. In this paper, we report the results of a comprehensive study to assess the feasibility of using crushed clay brick as coarse and fine aggregates in concrete masonry block production. The effects of the content of crushed coarse and fine clay brick aggregates (CBA) on the mechanical properties of non-structural concrete block were quantified. From the experimental test results, it was observed that incorporating the crushed clay brick aggregates had a significant influence on the properties of blocks. The hardened density and drying shrinkage of the block specimens decreased with an increase in CBA content. The use of CBA increased the water absorption of block specimens. The results suggested that the amount of crushed clay brick to be used in concrete masonry blocks should be controlled at less than 25% (coarse aggregate) and within 50-75% for fine aggregates.

  1. The antioxidant activities of six (1→3)-β-d-glucan derivatives prepared from yeast cell wall.

    PubMed

    Tang, Qilin; Huang, Gangliang; Zhao, Fengying; Zhou, Lu; Huang, Shiqi; Li, Hui

    2017-02-02

    The alkali-insoluble (1→3)-β-d-glucan (PJ) was extracted from yeast cell wall by acid-base method. The sulfated glucan (S-PJ), carboxymethylated glucan (CM-PJ), phosphorylated glucan (P-PJ), carboxymethylated-phosphorylated glucan (CP-PJ), carboxymethylated-sulfated glucan (CS-PJ), and sulfated-phosphorylated glucan (SP-PJ) were prepared and characterized, respectively. The reduction ability, hydroxyl radical/superoxide anion scavenging activities, and anti-lipid peroxidation effect of above-mentioned derivatives were assayed. It indicated that S-PJ had the significant reduction capacity, P-PJ had the obvious hydroxyl radical/superoxide anion scavenging activities and anti-lipid peroxidation effect.

  2. Flows in Stenotic Vessels

    NASA Astrophysics Data System (ADS)

    Berger, S. A.; Jou, L.-D.

    The relationship between flow in the arteries, particularly the wall shear stresses, and the sites where atherosclerosis develops has motivated much of the research on arterial flow in recent decades. It is now well accepted that it is sites where shear stresses are low, or change rapidly in time or space, that are most vulnerable. These conditions are likely to prevail at places where the vessel is curved; bifurcates; has a junction, a side branch, or other sudden change in flow geometry; and when the flow is unsteady. These flows, often but not always involving flow separation or secondary motions, are also the most difficult ones in fluid mechanics to analyze or compute. In this article we review the modeling studies and experiments on steady and unsteady, two-and three-dimensional flows in arteries, and in arterial geometries most relevant in the context of atherosclerosis. These include studies of normal vessels -- to identify, on the basis of the fluid mechanics, lesion foci -- and stenotic vessels, to model and measure flow in vessels after the lesions have evolved into plaques sufficiently large to significantly modify the flow. We also discuss recent work that elucidates many of the pathways by which mechanical forces, primarily the wall shear stresses, are transduced to effect changes in the arterial wall at the cellular, subcellular, and genetic level.

  3. Vesicle miR-195 derived from Endothelial Cells Inhibits Expression of Serotonin Transporter in Vessel Smooth Muscle Cells.

    PubMed

    Gu, Junzhong; Zhang, Huiyuan; Ji, Bingyang; Jiang, Hui; Zhao, Tao; Jiang, Rongcai; Zhang, Zhiren; Tan, Shengjiang; Ahmed, Asif; Gu, Yuchun

    2017-03-08

    Serotonin or 5-hydroxytryptamine (5-HT) has been shown to be essential in lots of physiological and pathological processes. It is well known that 5-HT and 5-HT transporter (5-HTT) play important roles in the pulmonary artery in pulmonary hypertension. However, little is known about the function of 5-HTT in other arteries. In this study we found that the expression of 5-HTT was elevated in injured carotid arteries and over-expression of 5-HTT induced proliferation of smooth muscle cells (SMCs); however, this phenotype could be reversed by knocking-down of 5-HTT or endothelial cells conditional medium (EC-CM). A 5-HTT inhibitor, fluoxetine, treated animals also exhibited reduced restenosis after injury. We identified that miR-195 was packaged in the extracellular vesicles from EC-CM. We further confirmed that extracellular vesicles could transfer miR-195 from ECs to SMCs to inhibit the expression of 5-HTT in SMCs and the proliferation of SMCs. These results provide the first evidence that ECs communicate with SMCs via micro-RNA195 in the regulation of the proliferation of SMCs through 5-HTT, which will contribute to a better understanding of communications between ECs and SMCs via micro-RNA. Our findings suggest a potential target for the control of vessel restenosis.

  4. Vesicle miR-195 derived from Endothelial Cells Inhibits Expression of Serotonin Transporter in Vessel Smooth Muscle Cells

    PubMed Central

    Gu, Junzhong; Zhang, Huiyuan; Ji, Bingyang; Jiang, Hui; Zhao, Tao; Jiang, Rongcai; Zhang, Zhiren; Tan, Shengjiang; Ahmed, Asif; Gu, Yuchun

    2017-01-01

    Serotonin or 5-hydroxytryptamine (5-HT) has been shown to be essential in lots of physiological and pathological processes. It is well known that 5-HT and 5-HT transporter (5-HTT) play important roles in the pulmonary artery in pulmonary hypertension. However, little is known about the function of 5-HTT in other arteries. In this study we found that the expression of 5-HTT was elevated in injured carotid arteries and over-expression of 5-HTT induced proliferation of smooth muscle cells (SMCs); however, this phenotype could be reversed by knocking-down of 5-HTT or endothelial cells conditional medium (EC-CM). A 5-HTT inhibitor, fluoxetine, treated animals also exhibited reduced restenosis after injury. We identified that miR-195 was packaged in the extracellular vesicles from EC-CM. We further confirmed that extracellular vesicles could transfer miR-195 from ECs to SMCs to inhibit the expression of 5-HTT in SMCs and the proliferation of SMCs. These results provide the first evidence that ECs communicate with SMCs via micro-RNA195 in the regulation of the proliferation of SMCs through 5-HTT, which will contribute to a better understanding of communications between ECs and SMCs via micro-RNA. Our findings suggest a potential target for the control of vessel restenosis. PMID:28272473

  5. Fluid-structure interaction analysis on the effect of vessel wall hypertrophy and stiffness on the blood flow in carotid artery bifurcation

    NASA Astrophysics Data System (ADS)

    Lee, Sang Hoon; Choi, Hyoung Gwon; Yoo, Jung Yul

    2012-11-01

    The effect of artery wall hypertrophy and stiffness on the flow field is investigated using three-dimensional finite element method for simulating the blood flow. To avoid the complexity due to the necessity of additional mechanical constraints, we use the combined formulation which includes both the fluid and structural equations of motion into single coupled variational equation. A P2P1 Galerkin finite element method is used to solve the Navier-Stokes equations for fluid flow and arbitrary Lagrangian-Eulerian formulation is used to achieve mesh movement. The Newmark method is employed for solving the dynamic equilibrium equations for linear elastic solid mechanics. The pulsatile, incompressible flows of Newtonian fluids constrained in the flexible wall are analyzed with Womersley velocity profile at the inlet and constant pressure at the outlet. The study shows that the stiffness of carotid artery wall affects significantly the flow phenomena during the pulse cycle. Similarly, it is found that the flow field is also strongly influenced by wall hypertrophy. This work was supported by Mid-career Researcher Program and Priority Research Centers Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2009-0079936 & 2011-0029613).

  6. Use of wastes derived from earthquakes for the production of concrete masonry partition wall blocks.

    PubMed

    Xiao, Zhao; Ling, Tung-Chai; Kou, Shi-Cong; Wang, Qingyuan; Poon, Chi-Sun

    2011-08-01

    Utilization of construction and demolition (C&D) wastes as recycled aggregates in the production of concrete and concrete products have attracted much attention in recent years. However, the presence of large quantities of crushed clay brick in some the C&D waste streams (e.g. waste derived collapsed masonry buildings after an earthquake) renders the recycled aggregates unsuitable for high grade use. One possibility is to make use of the low grade recycled aggregates for concrete block production. In this paper, we report the results of a comprehensive study to assess the feasibility of using crushed clay brick as coarse and fine aggregates in concrete masonry block production. The effects of the content of crushed coarse and fine clay brick aggregates (CBA) on the mechanical properties of non-structural concrete block were quantified. From the experimental test results, it was observed that incorporating the crushed clay brick aggregates had a significant influence on the properties of blocks. The hardened density and drying shrinkage of the block specimens decreased with an increase in CBA content. The use of CBA increased the water absorption of block specimens. The results suggested that the amount of crushed clay brick to be used in concrete masonry blocks should be controlled at less than 25% (coarse aggregate) and within 50-75% for fine aggregates.

  7. Blood Vessel Tension Tester

    NASA Technical Reports Server (NTRS)

    1978-01-01

    In the photo, a medical researcher is using a specially designed laboratory apparatus for measuring blood vessel tension. It was designed by Langley Research Center as a service to researchers of Norfolk General Hospital and Eastern Virginia Medical School, Norfolk, Virginia. The investigators are studying how vascular smooth muscle-muscle in the walls of blood vessels-reacts to various stimulants, such as coffee, tea, alcohol or drugs. They sought help from Langley Research Center in devising a method of measuring the tension in blood vessel segments subjected to various stimuli. The task was complicated by the extremely small size of the specimens to be tested, blood vessel "loops" resembling small rubber bands, some only half a millimeter in diameter. Langley's Instrumentation Development Section responded with a miniaturized system whose key components are a "micropositioner" for stretching a length of blood vessel and a strain gage for measuring the smooth muscle tension developed. The micropositioner is a two-pronged holder. The loop of Mood vessel is hooked over the prongs and it is stretched by increasing the distance between the prongs in minute increments, fractions of a millimeter. At each increase, the tension developed is carefully measured. In some experiments, the holder and specimen are lowered into the test tubes shown, which contain a saline solution simulating body fluid; the effect of the compound on developed tension is then measured. The device has functioned well and the investigators say it has saved several months research time.

  8. Derivation of factors for estimating the scatter of diagnostic x-rays from walls and ceiling slabs.

    PubMed

    Martin, C J; Sutton, D G; Magee, J; McVey, S; Williams, J R; Peet, D

    2012-12-01

    Computed tomography (CT) scanning rooms and interventional x-ray facilities with heavy workloads may require the installation of shielding to protect against radiation scattered from walls or ceiling slabs. This is particularly important for the protection of those operating x-ray equipment from within control cubicles who may be exposed to radiation scattered from the ceiling over the top of the protective barrier and round the side if a cubicle door is not included. Data available on the magnitude of this tertiary scatter from concrete slabs are limited. Moreover, there is no way in which tertiary scatter levels can be estimated easily for specific facilities. There is a need for a suitable method for quantification of tertiary scatter because of the increases in workloads of complex x-ray facilities. In this study diagnostic x-ray air kerma levels scattered from concrete and brick walls have been measured to verify scatter factors. The results have been used in a simulation of tertiary scatter for x-ray facilities involving summation of scatter contributions from elements across concrete ceiling slabs. The majority of the ceiling scatter air kerma to which staff behind a barrier will be exposed arises from the area between the patient/x-ray tube and the staff. The level depends primarily on the heights of the ceiling and protective barrier. A method has been developed to allow tertiary scatter levels to be calculated using a simple equation based on a standard arrangement for rooms with different ceiling and barrier heights. Coefficients have been derived for a CT facility and an interventional suite to predict tertiary scatter levels from the workload, so that consideration can be given to the protection options available.

  9. Endoplasmic reticulum-derived reactive oxygen species (ROS) is involved in toxicity of cell wall stress to Candida albicans.

    PubMed

    Yu, Qilin; Zhang, Bing; Li, Jianrong; Zhang, Biao; Wang, Honggang; Li, Mingchun

    2016-10-01

    The cell wall is an important cell structure in both fungi and bacteria, and hence becomes a common antimicrobial target. The cell wall-perturbing agents disrupt synthesis and function of cell wall components, leading to cell wall stress and consequent cell death. However, little is known about the detailed mechanisms by which cell wall stress renders fungal cell death. In this study, we found that ROS scavengers drastically attenuated the antifungal effect of cell wall-perturbing agents to the model fungal pathogen Candida albicans, and these agents caused remarkable ROS accumulation and activation of oxidative stress response (OSR) in this fungus. Interestingly, cell wall stress did not cause mitochondrial dysfunction and elevation of mitochondrial superoxide levels. Furthermore, the iron chelator 2,2'-bipyridyl (BIP) and the hydroxyl radical scavengers could not attenuate cell wall stress-caused growth inhibition and ROS accumulation. However, cell wall stress up-regulated expression of unfold protein response (UPR) genes, enhanced protein secretion and promoted protein folding-related oxidation of Ero1, an important source of ROS production. These results indicated that oxidation of Ero1 in the endoplasmic reticulum (ER), rather than mitochondrial electron transport and Fenton reaction, contributed to cell wall stress-related ROS accumulation and consequent growth inhibition. Our findings uncover a novel link between cell wall integrity (CWI), ER function and ROS production in fungal cells, and shed novel light on development of strategies promoting the antifungal efficacy of cell wall-perturbing agents against fungal infections.

  10. Vasoactive properties of antihypertensive lactoferrin-derived peptides in resistance vessels: Effects in small mesenteric arteries from SHR rats.

    PubMed

    García-Tejedor, Aurora; Manzanares, Paloma; Castelló-Ruiz, María; Moscardó, Antonio; Marcos, José F; Salom, Juan B

    2017-10-01

    Bovine lactoferrin (LF) hydrolysates and peptides identified thereof have shown antihypertensive effects in rat models, mainly but not exclusively by angiotensin-converting enzyme inhibition. In this study we aimed to assess the vasoactive effects and mechanisms of an ultrafiltered (<3kDa) pepsin LF hydrolysate (LFH) and a heptapeptide identified in a LF hydrolysate produced by yeast proteolysis (DPYKLRP) in peripheral resistance arteries from spontaneously hypertensive rats (SHRs). We used a myograph system for isometric tension recording in isolated small mesenteric arteries from SHRs. Direct vasoactive effects of LFH (30-100μg/mL) and DPYKLRP (30-100μM) were assessed in arteries precontracted with phenylephrine (PE, 10μM) or KCl (120mM), and in PE-precontracted arteries preincubated (10min) with the NO synthase inhibitor L-NAME (0.1mM) or the cyclooxygenase inhibitor indomethacin (10μM). Indirect vasoactive effects of LFH (30-100μg/mL) or DPYKLRP (30-100μM) preincubation (10min) on the relaxant responses to the NO donor sodium nitroprusside (SNP, 0.01-10μM) or acetylcholine (Ach, 1-100μM) were also studied in PE-precontracted arteries. Both LHF and DPYKLRP elicited direct relaxation of mesenteric arteries, by a mechanism involving NO release, counteracting modulation by prostanoids and K(+) efflux. Moreover, LF-derived peptides also showed indirect vasoactive effects by enhancing endothelium-dependent relaxation to Ach and endothelium-independent relaxation to SNP. In conclusion, LF-derived peptides show ex vivodirect and indirect relaxing effects in small mesenteric arteries from SHRs. These vasoactive effects would reduce vascular peripheral resistance in vivo, and thus contribute to their antihypertensive effects. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. Wrapped Wire Detects Rupture Of Pressure Vessel

    NASA Technical Reports Server (NTRS)

    Hunt, James B.

    1990-01-01

    Simple, inexpensive technique helps protect against damage caused by continuing operation of equipment after rupture or burnout of pressure vessel. Wire wrapped over area on outside of vessel where breakthrough most likely. If wall breaks or burns, so does wire. Current passing through wire ceases, triggering cutoff mechanism stopping flow in vessel to prevent further damage. Applied in other situations in which pipes or vessels fail due to overpressure, overheating, or corrosion.

  12. Wrapped Wire Detects Rupture Of Pressure Vessel

    NASA Technical Reports Server (NTRS)

    Hunt, James B.

    1990-01-01

    Simple, inexpensive technique helps protect against damage caused by continuing operation of equipment after rupture or burnout of pressure vessel. Wire wrapped over area on outside of vessel where breakthrough most likely. If wall breaks or burns, so does wire. Current passing through wire ceases, triggering cutoff mechanism stopping flow in vessel to prevent further damage. Applied in other situations in which pipes or vessels fail due to overpressure, overheating, or corrosion.

  13. Semi-automated segmentation of solid and GGO nodules in lung CT images using vessel-likelihood derived from local foreground structure

    NASA Astrophysics Data System (ADS)

    Yaguchi, Atsushi; Okazaki, Tomoya; Takeguchi, Tomoyuki; Matsumoto, Sumiaki; Ohno, Yoshiharu; Aoyagi, Kota; Yamagata, Hitoshi

    2015-03-01

    Reflecting global interest in lung cancer screening, considerable attention has been paid to automatic segmentation and volumetric measurement of lung nodules on CT. Ground glass opacity (GGO) nodules deserve special consideration in this context, since it has been reported that they are more likely to be malignant than solid nodules. However, due to relatively low contrast and indistinct boundaries of GGO nodules, segmentation is more difficult for GGO nodules compared with solid nodules. To overcome this difficulty, we propose a method for accurately segmenting not only solid nodules but also GGO nodules without prior information about nodule types. First, the histogram of CT values in pre-extracted lung regions is modeled by a Gaussian mixture model and a threshold value for including high-attenuation regions is computed. Second, after setting up a region of interest around the nodule seed point, foreground regions are extracted by using the threshold and quick-shift-based mode seeking. Finally, for separating vessels from the nodule, a vessel-likelihood map derived from elongatedness of foreground regions is computed, and a region growing scheme starting from the seed point is applied to the map with the aid of fast marching method. Experimental results using an anthropomorphic chest phantom showed that our method yielded generally lower volumetric measurement errors for both solid and GGO nodules compared with other methods reported in preceding studies conducted using similar technical settings. Also, our method allowed reasonable segmentation of GGO nodules in low-dose images and could be applied to clinical CT images including part-solid nodules.

  14. Experimental derivation of wall correction factors for ionization chambers used in high dose rate 192Ir source calibration.

    PubMed

    Maréchal, M H; de Almeida, C E; Ferreira, I H; Sibata, C H

    2002-01-01

    At present there are no specific primary standards for 192Ir high dose rate sources used in brachytherapy. Traceability to primary standards is guaranteed through the method recommended by the AAPM that derives the air kerma calibration factor for the 192Ir gamma rays as the average of the air kerma calibration factors for x-rays and 137Cs gamma-rays or the Maréchal et al. method that uses the energy-weighted air kerma calibration factors for 250 kV x rays and 60Co gamma rays as the air kerma calibration factor for the 192Ir gamma rays. In order to use these methods, it is necessary to use the same buildup cap for all energies and the appropriate wall correction factor for each chamber. This work describes experimental work used to derive the A(W) for four different ionization chambers and different buildup cap materials for the three energies involved in the Maréchal et al. method. The A(W) for the two most common ionization chambers used in hospitals, the Farmer NE 2571 and PTW N30001 is 0.995 and 0.997, respectively, for 250 kV x rays, 0.982 and 0.985 for 192Ir gamma rays, and 0.979 and 0.991 for 60Co gamma rays, all for a PMMA build-up cap of 0.550 gm cm(-2). A comparison between the experimental values and Monte Carlo calculations shows an agreement better than 0.9%. Availability of the A(W) correction factors for all commercial chambers allows users of the in-air calibration jig, provided by the manufacturer, to alternatively use the Maréchal et al. method. Calibration laboratories may also used this method for calibration of a well-type ionization chamber with a comparable accuracy to the AAPM method.

  15. Voluntary Consensus Organization Standards for Nondestructive Evaluation of Thin-Walled Metallic Liners and Composite Overwraps in Composite Overwrapped Pressure Vessels

    NASA Technical Reports Server (NTRS)

    Waller, Jess; Saulsberry, Regor

    2012-01-01

    NASA fracture control requirements outlined in NASA-STD-5009 and NASA-STD-5014 are predicated on the availability and use of sensitive nondestructive evaluation (NDE) methods that can detect and monitor defects, thereby providing data that can be used to predict failure or reduce the risk of failure in fracture critical components. However, in the case of composite materials and components, including composite overwrapped pressure vessels (COPVs), the effect of defects is poorly understood, the NDE methods used to evaluate locate and size defects are typically at lower technical readiness level than analogous NDE methods used for metals, and demonstration studies to verify the probability of detection (POD) are generally lacking or unavailable. These factors together make failure prediction of fracture critical composite materials and components based on size, quantity, or orientation of defects nearly impossible. Also, when inspecting metal liners in as-manufactured COPVs, sensitivity is lost and only the inner surface of the liner is accessible. Also, NDE of COPVs as applied during manufacturing varies significantly from manufacturer to manufacturer and has not yet been standardized. Although requirements exist to perform NDE immediately after manufacturing to establish initial integrity of the parts, procedural detail for NDE of composites is still nonexistent or under development. For example, in practice, only a visual inspection of COPVs is performed during manufacturing and service, leaving in question whether defects of concern, for example, bridging, overwrap winding anomalies, impact damage below visible threshold, out-of-family strain growth, and liner buckling have been adequately detected and monitored. To address these shortcomings, in 2005 the NASA Nondestructive Evaluation Working Group (NNWG) began funding work to develop and adopt standards for nondestructive evaluation of aerospace composites in collaboration with the American Society for Testing

  16. Relaxation oscillation model of hemodynamic parameters in the cerebral vessels

    NASA Astrophysics Data System (ADS)

    Cherevko, A. A.; Mikhaylova, A. V.; Chupakhin, A. P.; Ufimtseva, I. V.; Krivoshapkin, A. L.; Orlov, K. Yu

    2016-06-01

    Simulation of a blood flow under normality as well as under pathology is extremely complex problem of great current interest both from the point of view of fundamental hydrodynamics, and for medical applications. This paper proposes a model of Van der Pol - Duffing nonlinear oscillator equation describing relaxation oscillations of a blood flow in the cerebral vessels. The model is based on the patient-specific clinical experimental data flow obtained during the neurosurgical operations in Meshalkin Novosibirsk Research Institute of Circulation Pathology. The stability of the model is demonstrated through the variations of initial data and coefficients. It is universal and describes pressure and velocity fluctuations in different cerebral vessels (arteries, veins, sinuses), as well as in a laboratory model of carotid bifurcation. Derived equation describes the rheology of the ”blood stream - elastic vessel wall gelatinous brain environment” composite system and represents the state equation of this complex environment.

  17. Dimensional analysis of blood vessel images in real time

    NASA Astrophysics Data System (ADS)

    Smith, Peter R.; Eustaquio-Martin, Almudena; Thomason, Harry; Bennett, M.; Thurston, H.

    1996-01-01

    The physiology and pathology of dissected blood vessels are studied by perfusion myography combined with video microscopy. Images of the vessels are formed under diffuse white light illumination and contrast is achieved by differential absorption with respect to the vessel wall. To obtain the vessel dimensional information in quasi real time an edge-tracking algorithm is used, allowing the edges to be found by applying common image processing tools to a very small number of pixels rather than the whole image. Employing a low order optical model of the light transmission properties of vessels with circular cross section, a relationship between the positions of edges found by a typical image processing algorithm and actual dimensions is derived. The dimensional analysis is demonstrated on rat mesenteric resistance arteries (internal diameter less than 300 micrometer) mounted in a perfusion arteriograph. Segments of vessels are secured on two glass cannulae using single strands of a nylon braided suture. The artery is perfused with physiological salt solution and the perfusion pressure maintained at 60 mmHg before starting the experiment. Changes in vascular diameter to the vasoconstrictor noradrenaline and the endothelium-dependent vasodilator acetylcholine were then observed.

  18. Synchronized reconstitution of muscle fibers, peripheral nerves and blood vessels by murine skeletal muscle-derived CD34(-)/45 (-) cells.

    PubMed

    Tamaki, Tetsuro; Okada, Yoshinori; Uchiyama, Yoshiyasu; Tono, Kayoko; Masuda, Maki; Wada, Mika; Hoshi, Akio; Akatsuka, Akira

    2007-10-01

    In order to establish the practical isolation and usage of skeletal muscle-derived stem cells (MDSCs), we determined reconstitution capacity of CD34(-)/CD45(-) (Sk-DN) cells as a candidate somatic stem cell source for transplantation. Sk-DN cells were enzymatically isolated from GFP transgenic mice (C57/BL6N) skeletal muscle and sorted using fluorescence activated cell sorting (FACS), and expanded by collagen gel-based cell culture with bFGF and EGF. The number of Sk-DN cells was small after sorting (2-8 x 10(4)); however, the number increased 10-20 fold (2-16 x 10(5)) after 6 days of expansion culture, and the cells maintained immature state and multipotency, expressing mRNAs for mesodermal and ectodermal cell lineages. Transplantation of expanded Sk-DN cells into the severe muscle damage model (C57/BL6N wild-type) resulted in the synchronized reconstitution of blood vessels, peripheral nerves and muscle fibers following significant recovery of total muscle mass (57%) and contractile function (55%), whereas the non-cell-transplanted control group showed around 20% recovery in both factors. These reconstitution capacities were supported by the intrinsic plasticity of Sk-DN cells that can differentiate into muscular (skeletal muscle), vascular (pericyte, endothelial cell and smooth muscle) and peripheral nerve (Schwann cells and perineurium) cell lineages that was revealed by transplantation to non-muscle tissue (beneath renal capsule) and fluorescence in situ hybridization (FISH) analysis.

  19. A novel bispecific immunotoxin delivered by human bone marrow-derived mesenchymal stem cells to target blood vessels and vasculogenic mimicry of malignant gliomas.

    PubMed

    Zhang, Yonghong; Sun, Xinlin; Huang, Min; Ke, Yiquan; Wang, Jihui; Liu, Xiao

    2015-01-01

    In previous years, immunotoxins have been shown to be a greatly promising therapeutic tool for brain malignancies, such as gliomas. Human mesenchymal stem cells (hMSCs) exhibit tropism to tumor tissue. However, the effect of bispecific immunotoxins in malignant gliomas is still unknown. The aim of this study was to investigate the function of bispecific immunotoxins in human malignant gliomas. In the present study, the bispecific immunotoxin VEGF165-ephrin A1-PE38KDEL was established using deoxyribonucleic acid shuffling and cloning techniques. The VEGF165-ephrin A1-PE38KDEL was delivered by hMSCs to mouse malignant gliomas. The effects of the bispecific immunotoxins on glioma-derived blood vessels and vasculogenic mimicry to elucidate the molecular mechanisms underlying the antitumorigenic effects of immunotoxins were examined in vivo. In vitro, transfected hMSCs significantly inhibited the cell viability of gliomas cell lines U87 and U251 in a dose-dependent manner compared with untransfected hMSCs (P<0.01). In vivo, the intratumoral injection of engineered hMSCs was effective at inhibiting tumor growth in a malignant glioma tumor model. The bispecific immunotoxin secreted from hMSCs acts as a novel strategy for improving treatment options for malignant gliomas in the clinic.

  20. A probe for blood-vessel and spinal interiors

    NASA Technical Reports Server (NTRS)

    Frazer, R. E.

    1978-01-01

    Probe design allows insertion into lumen of blood vessels to perform oximetry and investigate plaque on interior vessel walls. Probe is more accurate than standard oximetry procedures of determining oxygenation of circulating blood.

  1. Plating Repair Of Nickel-Alloy Pressure Vessels

    NASA Technical Reports Server (NTRS)

    Ricklefs, Steve K.; Chagnon, Kevin M.

    1989-01-01

    Procedure for localized electrodeposition of nickel enables repair of small damaged nickel-based pressure vessels. Electrodeposition restores weakened areas of vessel wall to at least their former strength.

  2. Novel 3D ultrasound image-based biomarkers based on a feature selection from a 2D standardized vessel wall thickness map: a tool for sensitive assessment of therapies for carotid atherosclerosis

    NASA Astrophysics Data System (ADS)

    Chiu, Bernard; Li, Bing; Chow, Tommy W. S.

    2013-09-01

    With the advent of new therapies and management strategies for carotid atherosclerosis, there is a parallel need for measurement tools or biomarkers to evaluate the efficacy of these new strategies. 3D ultrasound has been shown to provide reproducible measurements of plaque area/volume and vessel wall volume. However, since carotid atherosclerosis is a focal disease that predominantly occurs at bifurcations, biomarkers based on local plaque change may be more sensitive than global volumetric measurements in demonstrating efficacy of new therapies. The ultimate goal of this paper is to develop a biomarker that is based on the local distribution of vessel-wall-plus-plaque thickness change (VWT-Change) that has occurred during the course of a clinical study. To allow comparison between different treatment groups, the VWT-Change distribution of each subject must first be mapped to a standardized domain. In this study, we developed a technique to map the 3D VWT-Change distribution to a 2D standardized template. We then applied a feature selection technique to identify regions on the 2D standardized map on which subjects in different treatment groups exhibit greater difference in VWT-Change. The proposed algorithm was applied to analyse the VWT-Change of 20 subjects in a placebo-controlled study of the effect of atorvastatin (Lipitor). The average VWT-Change for each subject was computed (i) over all points in the 2D map and (ii) over feature points only. For the average computed over all points, 97 subjects per group would be required to detect an effect size of 25% that of atorvastatin in a six-month study. The sample size is reduced to 25 subjects if the average were computed over feature points only. The introduction of this sensitive quantification technique for carotid atherosclerosis progression/regression would allow many proof-of-principle studies to be performed before a more costly and longer study involving a larger population is held to confirm the treatment

  3. Di-isodityrosine, a novel tetrametric derivative of tyrosine in plant cell wall proteins: a new potential cross-link.

    PubMed Central

    Brady, J D; Sadler, I H; Fry, S C

    1996-01-01

    A novel amino acid, di-isodityrosine, has been isolated from hydrolysates of cell walls of tomato cell culture. Analysis by UV spectrometry, partial derivatization with 2,4-dinitrofluorobenzene and mass and NMR spectrometry show that the compound is composed to two molecules of isodityrosine, joined by a biphenyl linkage. The possible reactions involved in the formation of this molecule in vivo are discussed, as is the possibility that it could form an interpolypeptide linkage between cell wall proteins such as extensin, and hence aid in the insolubilization of the protein in the wall. PMID:8670125

  4. Pectin and Xyloglucan Influence the Attachment of Salmonella enterica and Listeria monocytogenes to Bacterial Cellulose-Derived Plant Cell Wall Models

    PubMed Central

    Tan, Michelle S. F.; Rahman, Sadequr

    2015-01-01

    Minimally processed fresh produce has been implicated as a major source of foodborne microbial pathogens globally. These pathogens must attach to the produce in order to be transmitted. Cut surfaces of produce that expose cell walls are particularly vulnerable. Little is known about the roles that different structural components (cellulose, pectin, and xyloglucan) of plant cell walls play in the attachment of foodborne bacterial pathogens. Using bacterial cellulose-derived plant cell wall models, we showed that the presence of pectin alone or xyloglucan alone affected the attachment of three Salmonella enterica strains (Salmonella enterica subsp. enterica serovar Enteritidis ATCC 13076, Salmonella enterica subsp. enterica serovar Typhimurium ATCC 14028, and Salmonella enterica subsp. indica M4) and Listeria monocytogenes ATCC 7644. In addition, we showed that this effect was modulated in the presence of both polysaccharides. Assays using pairwise combinations of S. Typhimurium ATCC 14028 and L. monocytogenes ATCC 7644 showed that bacterial attachment to all plant cell wall models was dependent on the characteristics of the individual bacterial strains and was not directly proportional to the initial concentration of the bacterial inoculum. This work showed that bacterial attachment was not determined directly by the plant cell wall model or bacterial physicochemical properties. We suggest that attachment of the Salmonella strains may be influenced by the effects of these polysaccharides on physical and structural properties of the plant cell wall model. Our findings improve the understanding of how Salmonella enterica and Listeria monocytogenes attach to plant cell walls, which may facilitate the development of better ways to prevent the attachment of these pathogens to such surfaces. PMID:26567310

  5. Pressure wall patch

    NASA Technical Reports Server (NTRS)

    Williamsen, Joel E. (Inventor); Weddendorf, Bruce C. (Inventor)

    1994-01-01

    A rigid patch body for placing over a damaged portion (hole) of an external wall of a pressurized vessel, such as a space vehicle or a habitat, is discussed. The rigid patch body allows an astronaut to make temporary repairs to the pressurized vessel from the exterior of the vessel, which enables more permanent repairs to be made from the interior of the vessel. The pressure wall patch of the present invention includes a floor surrounded by four side members. Each side member includes a threaded screw for anchoring the patch body to the external wall of the pressurized vessel and a recess in its lower surface for supporting an inflatable bladder for surrounding the damaged portion (hole) of the external wall to seal the area surrounding the damaged portion. This allows the vessel to be repressurized. The floor of the rigid patch body supports a source of gas that is connected to the gas supply valve and a gas supply gauge in communication with the gas supply valve and the inflatable bladder.

  6. Evaluation of in-vessel corium retention through external reactor vessel cooling for integral reactor

    SciTech Connect

    Park, R. J.; Lee, J. R.; Kim, S. B.; Jin, Y.; Kim, H. Y.

    2012-07-01

    In-vessel corium retention through external reactor vessel cooling (IVR-ERVC) for a small integral reactor has been evaluated to determine the thermal margin for the prevention of a reactor vessel failure. A thermal load analysis from the corium pool to the outer reactor vessel wall in the lower plenum of the reactor vessel has been performed to determine the heat flux distribution. The critical heat flux (CHF) on the outer reactor vessel wall has been determined to fix the maximum heat removal rate through the external coolant between the outer reactor vessel and the insulation of the reactor vessel. Finally, the thermal margin has been evaluated by comparison of the thermal load with the maximum heat removal rate of the CHF on the outer reactor vessel wall. The maximum heat flux from the corium pool to the outer reactor vessel is estimated at approximately 0.25 MW/m{sup 2} in the metallic layer because of the focusing effect. The CHF of the outer reactor vessel is approximately 1.1 MW/m{sup 2} because of a two phase natural circulation mass flow. Since the thermal margin for the IVR-ERVC is sufficient, the reactor vessel integrity is maintained during a severe accident of a small integral reactor. (authors)

  7. Vessel structural support system

    DOEpatents

    Jenko, James X.; Ott, Howard L.; Wilson, Robert M.; Wepfer, Robert M.

    1992-01-01

    Vessel structural support system for laterally and vertically supporting a vessel, such as a nuclear steam generator having an exterior bottom surface and a side surface thereon. The system includes a bracket connected to the bottom surface. A support column is pivotally connected to the bracket for vertically supporting the steam generator. The system also includes a base pad assembly connected pivotally to the support column for supporting the support column and the steam generator. The base pad assembly, which is capable of being brought to a level position by turning leveling nuts, is anchored to a floor. The system further includes a male key member attached to the side surface of the steam generator and a female stop member attached to an adjacent wall. The male key member and the female stop member coact to laterally support the steam generator. Moreover, the system includes a snubber assembly connected to the side surface of the steam generator and also attached to the adjacent wall for dampening lateral movement of the steam generator. In addition, the system includes a restraining member of "flat" attached to the side surface of the steam generator and a bumper attached to the adjacent wall. The flat and the bumper coact to further laterally support the steam generator.

  8. Genotype, development and tissue-derived variation of cell-wall properties in the lignocellulosic energy crop Miscanthus

    PubMed Central

    da Costa, Ricardo M. F.; Lee, Scott J.; Allison, Gordon G.; Hazen, Samuel P.; Winters, Ana; Bosch, Maurice

    2014-01-01

    Background and Aims Species and hybrids of the genus Miscanthus contain attributes that make them front-runners among current selections of dedicated bioenergy crops. A key trait for plant biomass conversion to biofuels and biomaterials is cell-wall quality; however, knowledge of cell-wall composition and biology in Miscanthus species is limited. This study presents data on cell-wall compositional changes as a function of development and tissue type across selected genotypes, and considers implications for the development of miscanthus as a sustainable and renewable bioenergy feedstock. Methods Cell-wall biomass was analysed for 25 genotypes, considering different developmental stages and stem vs. leaf compositional variability, by Fourier transform mid-infrared spectroscopy and lignin determination. In addition, a Clostridium phytofermentans bioassay was used to assess cell-wall digestibility and conversion to ethanol. Key Results Important cell-wall compositional differences between miscanthus stem and leaf samples were found to be predominantly associated with structural carbohydrates. Lignin content increased as plants matured and was higher in stem tissues. Although stem lignin concentration correlated inversely with ethanol production, no such correlation was observed for leaves. Leaf tissue contributed significantly to total above-ground biomass at all stages, although the extent of this contribution was genotype-dependent. Conclusions It is hypothesized that divergent carbohydrate compositions and modifications in stem and leaf tissues are major determinants for observed differences in cell-wall quality. The findings indicate that improvement of lignocellulosic feedstocks should encompass tissue-dependent variation as it affects amenability to biological conversion. For gene–trait associations relating to cell-wall quality, the data support the separate examination of leaf and stem composition, as tissue-specific traits may be masked by considering only

  9. Genotype, development and tissue-derived variation of cell-wall properties in the lignocellulosic energy crop Miscanthus

    DOE PAGES

    da Costa, Ricardo M. F.; Lee, Scott J.; Allison, Gordon G.; ...

    2014-04-15

    Species and hybrids of the genus Miscanthus contain attributes that make them front-runners among current selections of dedicated bioenergy crops. A key trait for plant biomass conversion to biofuels and biomaterials is cell-wall quality; however, knowledge of cell-wall composition and biology in Miscanthus species is limited. This study presents data on cell-wall compositional changes as a function of development and tissue type across selected genotypes, and considers implications for the development of miscanthus as a sustainable and renewable bioenergy feedstock. Cell-wall biomass was analysed for 25 genotypes, considering different developmental stages and stem vs. leaf compositional variability, by Fourier transformmore » mid-infrared spectroscopy and lignin determination. In addition, a Clostridium phytofermentans bioassay was used to assess cell-wall digestibility and conversion to ethanol. Important cell-wall compositional differences between miscanthus stem and leaf samples were found to be predominantly associated with structural carbohydrates. Lignin content increased as plants matured and was higher in stem tissues. Although stem lignin concentration correlated inversely with ethanol production, no such correlation was observed for leaves. Leaf tissue contributed significantly to total above-ground biomass at all stages, although the extent of this contribution was genotype-dependent. In conclusion, it is hypothesized that divergent carbohydrate compositions and modifications in stem and leaf tissues are major determinants for observed differences in cell-wall quality. The findings indicate that improvement of lignocellulosic feedstocks should encompass tissue-dependent variation as it affects amenability to biological conversion. For gene-trait associations relating to cell-wall quality, the data support the separate examination of leaf and stem composition, as tissue-specific traits may be masked by considering only total above-ground biomass

  10. Robust vessel segmentation

    NASA Astrophysics Data System (ADS)

    Bock, Susanne; Kühnel, Caroline; Boskamp, Tobias; Peitgen, Heinz-Otto

    2008-03-01

    In the context of cardiac applications, the primary goal of coronary vessel analysis often consists in supporting the diagnosis of vessel wall anomalies, such as coronary plaque and stenosis. Therefore, a fast and robust segmentation of the coronary tree is a very important but challenging task. We propose a new approach for coronary artery segmentation. Our method is based on an earlier proposed progressive region growing. A new growth front monitoring technique controls the segmentation and corrects local leakage by retrospective detection and removal of leakage artifacts. While progressively reducing the region growing threshold for the whole image, the growing process is locally analyzed using criteria based on the assumption of tubular, gradually narrowing vessels. If a voxel volume limit or a certain shape constraint is exceeded, the growing process is interrupted. Voxels affected by a failed segmentation are detected and deleted from the result. To avoid further processing at these positions, a large neighborhood is blocked for growing. Compared to a global region growing without local correction, our new local growth control and the adapted correction can deal with contrast decrease even in very small coronary arteries. Furthermore, our algorithm can efficiently handle noise artifacts and partial volume effects near the myocardium. The enhanced segmentation of more distal vessel parts was tested on 150 CT datasets. Furthermore, a comparison between the pure progressive region growing and our new approach was conducted.

  11. 46 CFR 4.03-35 - Nuclear vessel.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... INVESTIGATIONS Definitions § 4.03-35 Nuclear vessel. The term nuclear vessel means any vessel in which power for propulsion, or for any other purpose, is derived from nuclear energy; or any vessel handling or processing... 46 Shipping 1 2014-10-01 2014-10-01 false Nuclear vessel. 4.03-35 Section 4.03-35 Shipping...

  12. 46 CFR 4.03-35 - Nuclear vessel.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... INVESTIGATIONS Definitions § 4.03-35 Nuclear vessel. The term nuclear vessel means any vessel in which power for propulsion, or for any other purpose, is derived from nuclear energy; or any vessel handling or processing... 46 Shipping 1 2011-10-01 2011-10-01 false Nuclear vessel. 4.03-35 Section 4.03-35 Shipping...

  13. 46 CFR 4.03-35 - Nuclear vessel.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... INVESTIGATIONS Definitions § 4.03-35 Nuclear vessel. The term nuclear vessel means any vessel in which power for propulsion, or for any other purpose, is derived from nuclear energy; or any vessel handling or processing... 46 Shipping 1 2012-10-01 2012-10-01 false Nuclear vessel. 4.03-35 Section 4.03-35 Shipping...

  14. 46 CFR 4.03-35 - Nuclear vessel.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... INVESTIGATIONS Definitions § 4.03-35 Nuclear vessel. The term nuclear vessel means any vessel in which power for propulsion, or for any other purpose, is derived from nuclear energy; or any vessel handling or processing... 46 Shipping 1 2010-10-01 2010-10-01 false Nuclear vessel. 4.03-35 Section 4.03-35 Shipping...

  15. 46 CFR 4.03-35 - Nuclear vessel.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... INVESTIGATIONS Definitions § 4.03-35 Nuclear vessel. The term nuclear vessel means any vessel in which power for propulsion, or for any other purpose, is derived from nuclear energy; or any vessel handling or processing... 46 Shipping 1 2013-10-01 2013-10-01 false Nuclear vessel. 4.03-35 Section 4.03-35 Shipping...

  16. JPDR vessel steel examination

    SciTech Connect

    Corwin, W.R.; Broadhead, B.L.; Sokolov, M.A.

    1995-10-01

    There is a need to validate the results of irradiation effects research by the examination of material taken directly from the wall of a pressure vessel which has been irradiated during normal service. This task has been included with the HSSI Program to provide just such an evaluation of material from the wall of the pressure vessel from the JPDR. The JPDR was a small BWR that began operation in 1963. It operated until 1976, accumulating {approximately}17,000 h of operation, of which a little over 14,000 h were with the original 45-MWTh core, and the remaining fraction, late in life, with an upgraded 90-MWTh core. The pressure vessel of the JPDR, fabricated from A 302, grade B, modified steel with an internal weld overlay cladding of 304 stainless steel, is approximately 2 m ID and 73 mm thick. It was fabricated from two shell halves joined by longitudinal seam welds located 180{degrees} from each other. The rolling direction of the shell plates is parallel to the axis of the vessel. It operated at 273{degrees}C and reached a maximum fluence of about 2.3 x 10{sup 18} n/cm{sup 2} (> 1 MeV). The impurity contents in the base metal are 0.10 to 0.11% Cu and 0.010 to 0.017% P with a nickel content of 0.63 to 0.65%. Impurity contents of the weld metal are 0.11 to 0.14% Cu and 0.025 to 0.039% P with a nickel content of 0.59%.

  17. Angiogenesis and vasculogenesis: inducing the growth of new blood vessels and wound healing by stimulation of bone marrow-derived progenitor cell mobilization and homing.

    PubMed

    Velazquez, Omaida C

    2007-06-01

    During embryonic development, the vasculature is among the first organs to form and is in charge of maintaining metabolic homeostasis by supplying oxygen and nutrients and removing waste products. As one would expect, blood vessels are critical not only for organ growth in the embryo but also for repair of wounded tissue in the adult. An imbalance in angiogenesis (a time-honored term that globally refers to the growth of new blood vessels) contributes to the pathogenesis of numerous malignant, inflammatory, ischemic, infectious, immune, and wound-healing disorders. This review focuses on the central role of the growth of new blood vessels in ischemic and diabetic wound healing and defines the most current nomenclature that describes the neovascularization process in wounds. There are now two well-defined, distinct, yet interrelated processes for the formation of postnatal new blood vessels, angiogenesis, and vasculogenesis. Reviewed are recent new data on vasculogenesis that promise to advance the field of wound healing.

  18. Light-weight spherical submergence vessel

    NASA Technical Reports Server (NTRS)

    Baker, I.

    1974-01-01

    Design vessel with very low thickness-to-radius ratio to obtain low weight, and fabricate it with aid of precision tracer-lathe to limit and control imperfections in spherical shape. Vessel is thin-walled, spherical, monocoque shell constructed from hemispheres joined with sealed and bolted meridional flange.

  19. 4D Blood Flow Reconstruction Over the Entire Ventricle From Wall Motion and Blood Velocity Derived From Ultrasound Data.

    PubMed

    Gomez, Alberto; de Vecchi, Adelaide; Jantsch, Martin; Shi, Wenzhe; Pushparajah, Kuberan; Simpson, John M; Smith, Nicolas P; Rueckert, Daniel; Schaeffter, Tobias; Penney, Graeme P

    2015-11-01

    We demonstrate a new method to recover 4D blood flow over the entire ventricle from partial blood velocity measurements using multiple 3D+t colour Doppler images and ventricular wall motion estimated using 3D+t BMode images. We apply our approach to realistic simulated data to ascertain the ability of the method to deal with incomplete data, as typically happens in clinical practice. Experiments using synthetic data show that the use of wall motion improves velocity reconstruction, shows more accurate flow patterns and improves mean accuracy particularly when coverage of the ventricle is poor. The method was applied to patient data from 6 congenital cases, producing results consistent with the simulations. The use of wall motion produced more plausible flow patterns and reduced the reconstruction error in all patients.

  20. Quantification of pulmonary arterial wall distensibility using parameters extracted from volumetric micro-CT images

    NASA Astrophysics Data System (ADS)

    Johnson, Roger H.; Karau, Kelly L.; Molthen, Robert C.; Dawson, Christopher A.

    1999-09-01

    Stiffening, or loss of distensibility, of arterial vessel walls is among the manifestations of a number of vascular diseases including pulmonary arterial hypertension. We are attempting to quantify the mechanical properties of vessel walls of the pulmonary arterial tree using parameters derived from high-resolution volumetric x-ray CT images of rat lungs. The pulmonary arterial trees of the excised lungs are filled with a contrast agent. The lungs are imaged with arterial pressures spanning the physiological range. Vessel segment diameters are measured from the inlet to the periphery, and distensibilities calculated from diameters as a function of pressure. The method shows promise as an adjunct to other morphometric techniques such as histology and corrosion casting. It possesses the advantages of being nondestructive, characterizing the vascular structures while the lungs are imaged rapidly and in a near-physiological state, and providing the ability to associate mechanical properties with vessel location in the intact tree hierarchy.

  1. Isolation and identification of arabinose mycolates of Cell Wall Skeleton (CWS) derived from Mycobacterium bovis BCG Tokyo 172 (SMP-105).

    PubMed

    Uenishi, Yuko; Kusunose, Naoto; Yano, Ikuya; Sunagawa, Makoto

    2010-03-01

    A unique hydrolysis method using a two-layer solution, consisting of diluted hydrochloric acid and toluene was developed to isolate whole arabinose mycolates from the cell wall skeleton of Mycobacterium bovis BCG Tokyo 172 (SMP-105) in order to reveal its pivotal role in enhancing immune responses against tumors.

  2. Determination of the Mechanical Properties of the Different Layers of Blood Vessels in vivo

    NASA Astrophysics Data System (ADS)

    Fung, Y. C.; Liu, S. Q.

    1995-03-01

    The structure and materials of the blood vessel wall are layered. This article presents the principle of a method to determine the mechanical properties of the different layers in vivo. In vivo measurement begets in vivo data and avoids pitfalls of in vitro tests of dissected specimens. With the proposed method, we can measure vessels of diameters 100 μm and up and obtain data on vascular smooth muscles and adventitia. To derive the full constitutive equations, one must first determine the zero-stress state, obtain the morphometric data on the thicknesses of the layers, and make mechanical measurements in the neighborhood of the zero-stress state. Then eight small perturbation experiments are done on each blood vessel in vivo to determine eight incremental elastic moduli of the two layers of the blood vessel wall. The calculation requires the morphometric data and the location of the neutral axis. The experiments are simple, the interpretation is definitive, but the analysis is somewhat sophisticated. The method will yield results that are needed to assess the stress and strain in the tissues of the blood vessel. The subject is important because blood vessels remodel themselves significantly and rapidly when their stress and strain deviate from their homeostatic values, and because cell proliferation, differentiation, adhesion, contraction, and locomotion depend on stress and strain in the tissue.

  3. Vessel segmentation in screening mammograms

    NASA Astrophysics Data System (ADS)

    Mordang, J. J.; Karssemeijer, N.

    2015-03-01

    Blood vessels are a major cause of false positives in computer aided detection systems for the detection of breast cancer. Therefore, the purpose of this study is to construct a framework for the segmentation of blood vessels in screening mammograms. The proposed framework is based on supervised learning using a cascade classifier. This cascade classifier consists of several stages where in each stage a GentleBoost classifier is trained on Haar-like features. A total of 30 cases were included in this study. In each image, vessel pixels were annotated by selecting pixels on the centerline of the vessel, control samples were taken by annotating a region without any visible vascular structures. This resulted in a total of 31,000 pixels marked as vascular and over 4 million control pixels. After training, the classifier assigns a vesselness likelihood to the pixels. The proposed framework was compared to three other vessel enhancing methods, i) a vesselness filter, ii) a gaussian derivative filter, and iii) a tubeness filter. The methods were compared in terms of area under the receiver operating characteristics curves, the Az values. The Az value of the cascade approach is 0:85. This is superior to the vesselness, Gaussian, and tubeness methods, with Az values of 0:77, 0:81, and 0:78, respectively. From these results, it can be concluded that our proposed framework is a promising method for the detection of vessels in screening mammograms.

  4. Regional expression of the platelet-derived growth factor and its receptors in a primate graft model of vessel wall assembly.

    PubMed Central

    Kraiss, L W; Raines, E W; Wilcox, J N; Seifert, R A; Barrett, T B; Kirkman, T R; Hart, C E; Bowen-Pope, D F; Ross, R; Clowes, A W

    1993-01-01

    Healing baboon polytetrafluoroethylene grafts express PDGF mRNA in the neointima. Perfusates of graft segments also contain PDGF-like mitogenic activity. To extend these findings, we studied the expression and regional distribution of the PDGF protein isoforms and their receptors in this prosthetic graft model. By immunohistochemistry, as well as ELISA and Western blot analysis of tissue extracts, both PDGF-A and PDGF-B were identified in macrophages within the interstices of the synthetic material. In contrast, the neointima contained predominantly PDGF-A localized to the endothelial surface and the immediate subjacent smooth muscle cell layers. Tissue extracts of neointima and graft material were mitogenic for baboon aortic smooth muscle cells in culture; nearly all of this proliferative activity was blocked by a neutralizing anti-PDGF antibody. PDGF receptor beta-subunit mRNA and protein were easily detectable in the neointima and graft material. PDGF receptor alpha-subunit mRNA was also observed in the graft matrix and at lower levels in the neointima. This pattern of ligand and receptor expression further implicates locally produced PDGF as a regulator of neointimal smooth muscle cell growth in this model. The coexpression of ligand and receptor in the macrophage-rich matrix also suggests that PDGF may participate in the foreign body response. Images PMID:8326002

  5. Multiple intra-tube junctions in the inner tube of peapod-derived double walled carbon nanotubes: theoretical study and experimental evidence.

    PubMed

    Xu, Ziwei; Li, Hui; Fujisawa, Kazunori; Kim, Yoong Ahm; Endo, Morinobu; Ding, Feng

    2012-01-07

    The coalescence process of fullerenes in the hollow core of single walled carbon nanotubes is systematically explored by the kinetic Monte Carlo method. Two elongation (or growth) modes via the coalescence (i) between an inner tube and fullerenes and (ii) between neighboring inner tubes are identified. It is found that the coalescence of two inner tubes mostly creates a very stable intra-tube junction which is composed of multiple pentagon-heptagon pairs. As a consequence, the study predicts that the inner tube of peapod derived double walled carbon nanotubes (DWNTs) must contain many intra-tube junctions. Careful high resolution transmission electron microscopy observation on peapod-grown DWNT sample provides experimental evidence of the presence of the junctions.

  6. The changes in the endothelial expression of cell adhesion molecules and iNOS in the vessel wall after the short-term administration of simvastatin in rabbit model of atherosclerosis.

    PubMed

    Nachtigal, Petr; Kopecky, Martin; Solichova, Dagmar; Zdansky, Petr; Semecky, Vladimir

    2005-02-01

    Cell adhesion molecules P-selectin, VCAM-1 and ICAM-1 play an important role in the pathogenesis of atherosclerosis. High levels of nitric oxide (NO) produced by inducible NO synthase (iNOS) have been associated with atherosclerotic processes. Simvastatin is an HMG-CoA reductase inhibitor responsible for many clinical benefits. The aim of this study was to detect and quantify changes in endothelial expression of P-selectin, VCAM-1, ICAM-1 and iNOS in the vessel wall after the shortterm administration of simvastatin in a rabbit model of atherosclerosis. Eighteen New Zealand White rabbits were randomly divided into three groups (n=6). In the cholesterol group, rabbits consumed an atherogenic diet (0.4% cholesterol) for eight weeks. In the simvastatin group, rabbits consumed an atherogenic diet for six weeks and then consumed an atherogenic diet supplemented with simvastatin (10 mg kg(-1)) for two weeks. Biochemical analysis showed that administration of simvastatin led to an almost two-fold lowering of the total serum cholesterol, VLDL, LDL and HDL, but not triglycerides, compared with the cholesterol-fed rabbits only. Stereological analysis of the immunohistochemical staining revealed that administration of simvastatin (10 mg kg(-1) daily) in an atherogenic diet decreased the endothelial expression of P-selectin, ICAM-1 and iNOS in both aortic arch and carotid artery compared with the cholesterol fed-rabbits only. We conclude that simvastatin has beneficial effects on endothelial function by decreasing expression of P-selectin, ICAM-1 and iNOS in endothelial cells in the very early stages of atherogenesis.

  7. Micro-CT image-derived metrics quantify arterial wall distensibility reduction in a rat model of pulmonary hypertension

    NASA Astrophysics Data System (ADS)

    Johnson, Roger H.; Karau, Kelly L.; Molthen, Robert C.; Haworth, Steven T.; Dawson, Christopher A.

    2000-04-01

    We developed methods to quantify arterial structural and mechanical properties in excised rat lungs and applied them to investigate the distensibility decrease accompanying chronic hypoxia-induced pulmonary hypertension. Lungs of control and hypertensive (three weeks 11% O2) animals were excised and a contrast agent introduced before micro-CT imaging with a special purpose scanner. For each lung, four 3D image data sets were obtained, each at a different intra-arterial contrast agent pressure. Vessel segment diameters and lengths were measured at all levels in the arterial tree hierarchy, and these data used to generate features sensitive to distensibility changes. Results indicate that measurements obtained from 3D micro-CT images can be used to quantify vessel biomechanical properties in this rat model of pulmonary hypertension and that distensibility is reduced by exposure to chronic hypoxia. Mechanical properties can be assessed in a localized fashion and quantified in a spatially-resolved way or as a single parameter describing the tree as a whole. Micro-CT is a nondestructive way to rapidly assess structural and mechanical properties of arteries in small animal organs maintained in a physiological state. Quantitative features measured by this method may provide valuable insights into the mechanisms causing the elevated pressures in pulmonary hypertension of differing etiologies and should become increasingly valuable tools in the study of complex phenotypes in small-animal models of important diseases such as hypertension.

  8. Ethambutol-mediated cell wall modification in recombinant Corynebacterium glutamicum increases the biotransformation rates of cyclohexanone derivatives.

    PubMed

    Yun, Ji-Yeong; Lee, Jung-Eun; Yang, Kyung-Mi; Cho, Suekyung; Kim, Arim; Kwon, Yong-Uk; Kwon, Yong-Euk; Park, Jin-Byung

    2012-01-01

    The effects of structural modification of cell wall on the biotransformation capability by recombinant Corynebacterium glutamicum cells, expressing the chnB gene encoding cyclohexanone monooxygenase of Acinetobacter calcoaceticus NCIMB 9871, were investigated. Baeyer-Villiger oxygenation of 2-(2'-acetoxyethyl) cyclohexanone (MW 170 Da) into R-7-(2'-acetoxyethyl)-2-oxepanone was used as a model reaction. The whole-cell biotransformation followed Michaelis-Menten kinetics. The V (max) and K (S) values were estimated as 96.8 U g(-1) of dry cells and 0.98 mM, respectively. The V (max) was comparable with that of cyclohexanone oxygenation, whereas the K (S) was almost eightfold higher. The K (S) value of 2-(2'-acetoxyethyl) cyclohexanone oxygenation was reduced by ca. 30% via altering the cell envelop structure of C. glutamicum with ethambutol, which inhibits arabinosyl transferases involved in the biosynthesis of cell wall arabinogalactan and mycolate layers. The higher whole-cell biotransformation rate was also observed in the oxygenation of ethyl 2-cyclohexanone acetate upon ethambutol treatment of the recombinant C. glutamicum. Therefore, it was assumed that the biotransformation efficiency of C. glutamicum-based biocatalysts, with respect to medium- to large-sized lipophilic organic substrates (MW > ca. 170), can be enhanced by engineering their cell wall outer layers, which are known to function as a formidable barrier to lipophilic molecules.

  9. Three-dimensional texture features from intensity and high-order derivative maps for the discrimination between bladder tumors and wall tissues via MRI.

    PubMed

    Xu, Xiaopan; Zhang, Xi; Tian, Qiang; Zhang, Guopeng; Liu, Yang; Cui, Guangbin; Meng, Jiang; Wu, Yuxia; Liu, Tianshuai; Yang, Zengyue; Lu, Hongbing

    2017-04-01

    This study aims to determine the three-dimensional (3D) texture features extracted from intensity and high-order derivative maps that could reflect textural differences between bladder tumors and wall tissues, and propose a noninvasive, image-based strategy for bladder tumor differentiation preoperatively. A total of 62 cancerous and 62 wall volumes of interest (VOI) were extracted from T2-weighted MRI datasets of 62 patients with pathologically confirmed bladder cancer. To better reflect heterogeneous distribution of tumor tissues, 3D high-order derivative maps (the gradient and curvature maps) were calculated from each VOI. Then 3D Haralick features based on intensity and high-order derivative maps and Tamura features based on intensity maps were extracted from each VOI. Statistical analysis and recursive feature elimination-based support vector machine classifier (RFE-SVM) was proposed to first select the features with significant differences and then obtain a more predictive and compact feature subset to verify its differentiation performance. From each VOI, a total of 58 texture features were derived. Among them, 37 features showed significant inter-class differences ([Formula: see text]). With 29 optimal features selected by RFE-SVM, the classification results namely the sensitivity, specificity, accuracy and area under the curve (AUC) of the receiver operating characteristics were 0.9032, 0.8548, 0.8790 and 0.9045, respectively. By using synthetic minority oversampling technique to augment the sample number of each group to 200, the sensitivity, specificity, accuracy an AUC value of the feature selection-based classification were improved to 0.8967, 0.8780, 0.8874 and 0.9416, respectively. Our results suggest that 3D texture features derived from intensity and high-order derivative maps can better reflect heterogeneous distribution of cancerous tissues. Texture features optimally selected together with sample augmentation could improve the performance on

  10. Tailoring vessel morphology in vivo

    NASA Astrophysics Data System (ADS)

    Gould, Daniel Joseph

    Tissue engineering is a rapidly growing field which seeks to provide alternatives to organ transplantation in order to address the increasing need for transplantable tissues. One huge hurdle in this effort is the provision of thick tissues; this hurdle exists because currently there is no way to provide prevascularized or rapidly vascularizable scaffolds. To design thick, vascularized tissues, scaffolds are needed that can induce vessels which are similar to the microvasculature found in normal tissues. Angiogenic biomaterials are being developed to provide useful scaffolds to address this problem. In this thesis angiogenic and cell signaling and adhesion factors were incorporated into a biomimetic poly(ethylene glycol) (PEG) hydrogel system. The composition of these hydrogels was precisely tuned to induce the formation of differing vessel morphology. To sensitively measure induced microvascular morphology and to compare it to native microvessels in several tissues, this thesis developed an image-based tool for quantification of scale invariant and classical measures of vessel morphology. The tool displayed great utility in the comparison of native vessels and remodeling vessels in normal tissues. To utilize this tool to tune the vessel response in vivo, Flk1::myr-mCherry fluorescently labeled mice were implanted with Platelet Derived Growth Factor-BB (PDGF-BB) and basic Fibroblast Growth Factor (FGF-2) containing PEG-based hydrogels in a modified mouse corneal angiogenesis assay. Resulting vessels were imaged with confocal microscopy, analyzed with the image based tool created in this thesis to compare morphological differences between treatment groups, and used to create a linear relationship between space filling parameters and dose of growth factor release. Morphological parameters of native mouse tissue vessels were then compared to the linear fit to calculate the dose of growth factors needed to induce vessels similar in morphology to native vessels

  11. Angiogenesis & Vasculogenesis: Inducing the growth of new blood vessels and wound healing by stimulation of Bone Marrow Derived Progenitor Cell Mobilization and Homing

    PubMed Central

    Velazquez, Omaida C.

    2009-01-01

    During embryonic development, the vasculature is among the first organs to form and is in charge of maintaining metabolic homeostasis by supplying oxygen and nutrients and removing waste products. As one would expect, blood vessels are critical not only for organ growth in the embryo, but also for repair of wounded tissue in the adult. An imbalance in ‘Angiogenesis’ (a time-honored term that globally refers to the growth of new blood vessels) contributes to the pathogenesis of numerous malignant, inflammatory, ischemic, infectious, immune, and wound healing disorders. In this review, we will focus on the central role of the growth of new blood vessels in ischemic and diabetic wound healing. We define the most current nomenclature that describes the neovascularization process in wounds. There are now two well defined, distinct, yet interrelated processes for the formation of post-natal new blood vessels, angiogenesis and vasculogenesis. We review recent new data on vasculogenesis that promises to advance the field of wound healing. PMID:17544023

  12. Structure function tensor scaling in the logarithmic region derived from the attached eddy model of wall-bounded turbulent flows

    NASA Astrophysics Data System (ADS)

    Yang, X. I. A.; Baidya, R.; Johnson, P.; Marusic, I.; Meneveau, C.

    2017-06-01

    We investigate the scaling of the velocity structure function tensor Di j(r ,z ) in high Reynolds number wall-bounded turbulent flows, within the framework provided by the Townsend attached eddy hypothesis. Here i ,j =1 ,2 ,3 denote velocity components in the three Cartesian directions, and r is a general spatial displacement vector. We consider spatial homogeneous conditions in wall-parallel planes and dependence on wall-normal distance is denoted by z . At small scales (r =|r |≪z ) where turbulence approaches local isotropy, Di j(r ,z ) can be fully characterized as a function of r and the height-dependent dissipation rate ɛ (z ) , using the classical Kolmogorov scalings. At larger distances in the logarithmic range, existing previous studies have focused mostly on the scaling of Di j for r in the streamwise direction and for the streamwise velocity component (i =j =1 ) only. No complete description is available for Di j(r ,z ) for all i ,j , and r directions. In this paper we show that the hierarchical random additive process model for turbulent fluctuations in the logarithmic range (a model based on the Townsend's attached eddy hypothesis) may be used to make new predictions on the scaling of Di j(r ,z ) for all velocity components and in all two-point displacement directions. Some of the generalized scaling relations of Di j(r ,z ) in the logarithmic region are then compared to available data. Nevertheless, a number of predictions cannot yet be tested in detail, due to a lack of simultaneous two-point measurements with arbitrary cross-plane displacements, calling for further experiments to be conducted at high Reynolds numbers.

  13. A mixture of peptides and sugars derived from plant cell walls increases plant defense responses to stress and attenuates ageing-associated molecular changes in cultured skin cells.

    PubMed

    Apone, Fabio; Tito, Annalisa; Carola, Antonietta; Arciello, Stefania; Tortora, Assunta; Filippini, Lucio; Monoli, Irene; Cucchiara, Mirna; Gibertoni, Simone; Chrispeels, Maarten J; Colucci, Gabriella

    2010-02-15

    Small peptides and aminoacid derivatives have been extensively studied for their effect of inducing plant defense responses, and thus increasing plant tolerance to a wide range of abiotic stresses. Similarly to plants, these compounds can activate different signaling pathways in mammalian skin cells as well, leading to the up-regulation of anti-aging specific genes. This suggests the existence of analogous defense response mechanisms, well conserved both in plants and animal cells. In this article, we describe the preparation of a new mixture of peptides and sugars derived from the chemical and enzymatic digestion of plant cell wall glycoproteins. We investigate the multiple roles of this product as potential "biostimulator" to protect plants from abiotic stresses, and also as potential cosmeceutical. In particular, the molecular effects of the peptide/sugar mixture of inducing plant defense responsive genes and protecting cultured skin cells from oxidative burst damages were deeply evaluated.

  14. The TPX vacuum vessel and in-vessel components

    SciTech Connect

    Heitzenroeder, P.; Bialek, J.; Ellis, R.; Kessel, C.; Liew, S.

    1994-11-01

    The Tokamak Physics Experiment (TPX) is a superconducting tokamak with double-null divertors. TPX is designed for 1000-second discharges with the capability of being upgraded to steady state operation. High neutron yields resulting from the long duration discharges require that special consideration be given to materials and maintainability. A unique feature of the TPX is the use of a low activation, titanium alloy vacuum vessel. Double-wall vessel construction is used since it offers an efficient solution for shielding, bakeout and cooling. Contained within the vacuum vessel are the passive coil system, Plasma Facing Components (PFCs), magnetic diagnostics, and the internal control coils. All PFCs utilize carbon-carbon composites for exposed surfaces.

  15. The TPX vacuum vessel and in-vessel components

    SciTech Connect

    Heitzenroeder, P.; Bialek, J.; Ellis, R.; Kessel, C.; Liew, S.

    1994-07-01

    The Tokamak Physics Experiment (TPX) is a superconducting tokamak with double-null diverters. TPX is designed for 1,000-second discharges with the capability of being upgraded to steady state operation. High neutron yields resulting from the long duration discharges require that special consideration be given to materials and maintainability. A unique feature of the TPX is the use of a low activation, titanium alloy vacuum vessel. Double-wall vessel construction is used since it offers an efficient solution for shielding, bakeout and cooling. Contained within the vacuum vessel are the passive coil system, Plasma Facing Components (PFCs), magnetic diagnostics, and the internal control coils. All PFCs utilize carbon-carbon composites for exposed surfaces.

  16. Solutions of the Maxwell viscoelastic equations for displacement and stress distributions within the arterial wall

    NASA Astrophysics Data System (ADS)

    Hodis, S.; Zamir, M.

    2008-08-01

    Mechanical events within the thickness of the vessel wall caused by pulsatile blood flow are considered, with focus on axial dynamics of the wall, driven by the oscillatory drag force exerted by the fluid on the endothelial layer of the wall. It is shown that the focus on the axial direction makes it possible to derive simplified equations of motion which, combined with a viscoelastic model of the wall material, makes it possible in turn to obtain solutions in closed form for the displacement and stress of material elements within the wall. The viscoelastic model allows a study of the dynamics of the wall with different ratios of viscosity to elasticity of the wall material, to mimic changes in the properties of the arterial wall caused by disease or aging. It is found that when the wall is highly viscous the displacements and stresses caused by the flow are confined to a thin layer close to the inner boundary of the wall, while as the wall material becomes less viscous and more rigid the displacements and stresses spread deeper into the thickness of the wall to affect most of its elements.

  17. Acoustic scattering from a contrast agent microbubble near an elastic wall of finite thickness

    NASA Astrophysics Data System (ADS)

    Doinikov, Alexander A.; Aired, Leila; Bouakaz, Ayache

    2011-11-01

    Interest in the problem under consideration in this study is motivated by targeted ultrasound imaging where one has to deal with microbubble contrast agents pulsating near blood vessel walls. A modified Rayleigh-Plesset equation is derived that describes the oscillation of a contrast agent microbubble near an elastic wall of finite thickness. It is assumed that the medium behind the wall is a fluid but it is shown that the equation obtained is easily transformable to the case that the medium behind the wall is an elastic solid. In contrast to the model of a rigid wall, which predicts decreasing natural frequency of a bubble near the wall, the elastic wall model reveals that the bubble natural frequency can both decrease and increase, and in cases of interest for medical applications, the bubble natural frequency usually increases. It is found that the influence of an elastic wall on the acoustic response of a bubble is determined by the ratio between a cumulative parameter, which integrally characterizes the mechanical properties of the wall and has the dimension of density, and the density of the liquid surrounding the bubble. It is shown that the acoustic influence of the arterial wall on the bubble is weak and apparently cannot be used to recognize the moment when the bubble approaches the wall. However, in experiments where the behavior of bubbles near various plastic walls is observed, changes in the bubble response, such as increasing natural frequency and decreasing oscillation amplitude, are detectable.

  18. Neutron Assay System for Confinement Vessel Disposition

    SciTech Connect

    Frame, Katherine C.; Bourne, Mark M.; Crooks, William J.; Evans, Louise; Mayo, Douglas R.; Miko, David K.; Salazar, William R.; Stange, Sy; Valdez, Jose I.; Vigil, Georgiana M.

    2012-07-13

    Los Alamos National Laboratory has a number of spherical confinement vessels (CVs) remaining from tests involving nuclear materials. These vessels have an inner diameter of 6 feet with 1-inch thick steel walls. The goal of the Confinement Vessel Disposition (CVD) project is to remove debris and reduce contamination inside the CVs. The Confinement Vessel Assay System (CVAS) was developed to measure the amount of special nuclear material (SNM) in CVs before and after cleanout. Prior to cleanout, the system will be used to perform a verification measurement of each vessel. After cleanout, the system will be used to perform safeguards-quality assays of {le}100-g {sup 239}Pu equivalent in a vessel for safeguards termination. The CVAS has been tested and calibrated in preparation for verification and safeguards measurements.

  19. Qualitative and quantitative analysis of anthraquinone derivatives in rhizomes of tissue culture-raised Rheum emodi Wall. plants.

    PubMed

    Malik, Sonia; Sharma, Nandini; Sharma, Upendra K; Singh, Narendra P; Bhushan, Shashi; Sharma, Madhu; Sinha, Arun K; Ahuja, Paramvir S

    2010-06-15

    This paper presents quantification of five anthraquinone derivatives (emodin glycoside, chrysophanol glycoside, emodin, chrysophanol and physcion) in rhizomes of hardened micro-propagated Rheum emodi plants using high-performance liquid chromatography (HPLC). Aseptic shoot cultures were raised using rhizome buds. Shoot multiplication occurred in both agar gelled and liquid Murashige and Skoog (MS) medium supplemented with 10.0 microM 6-benzylaminopurine (BAP) and 5.0 microM indole-3-butyric acid (IBA). Rooted plantlets obtained on plant growth regulator (PGR)-free medium were transferred to soil with 92% survival. HPLC analysis revealed the presence of five anthraquinone derivatives: emodin glycoside, chrysophanol glycoside, emodin, chrysophanol and physcion in rhizomes of tissue culture-raised plants. Only emodin glycoside (1) and chrysophanol glycoside (2) were present in 6-month-old hardened tissue cultured plants. In addition, the other three derivatives (emodin (3), chrysophanol (4) and physcion (5)) were also detected after 9 months.

  20. Acrolein generation stimulates hypercontraction in isolated human blood vessels

    SciTech Connect

    Conklin, D.J. . E-mail: dj.conklin@louisville.edu; Bhatnagar, A.; Cowley, H.R.; Johnson, G.H.; Trent, M.B.; Boor, P.J.

    2006-12-15

    Increased risk of vasospasm, a spontaneous hyperconstriction, is associated with atherosclerosis, cigarette smoking, and hypertension-all conditions involving oxidative stress, lipid peroxidation, and inflammation. To test the role of the lipid peroxidation- and inflammation-derived aldehyde, acrolein, in human vasospasm, we developed an ex vivo model using human coronary artery bypass graft (CABG) blood vessels and a demonstrated acrolein precursor, allylamine. Allylamine induces hypercontraction in isolated rat coronary artery in a semicarbazide-sensitive amine oxidase activity (SSAO) dependent manner. Isolated human CABG blood vessels (internal mammary artery, radial artery, saphenous vein) were used to determine: (1) vessel responses and sensitivity to acrolein, allylamine, and H{sub 2}O{sub 2} exposure (1 {mu}M-1 mM), (2) SSAO dependence of allylamine-induced effects using SSAO inhibitors (semicarbazide, 1 mM; MDL 72274-E, active isomer; MDL 72274-Z, inactive isomer; 100 {mu}M), (3) the vasoactive effects of two other SSAO amine substrates, benzylamine and methylamine, and (4) the contribution of extracellular Ca{sup 2+} to hypercontraction. Acrolein or allylamine but not H{sub 2}O{sub 2}, benzylamine, or methylamine stimulated spontaneous and pharmacologically intractable hypercontraction in CABG blood vessels that was similar to clinical vasospasm. Allylamine-induced hypercontraction and blood vessel SSAO activity were abolished by pretreatment with semicarbazide or MDL 72274-E but not by MDL 72274-Z. Allylamine-induced hypercontraction also was significantly attenuated in Ca{sup 2+}-free buffer. In isolated aorta of spontaneously hypertensive rat, allylamine-induced an SSAO-dependent contraction and enhanced norepinephrine sensitivity but not in Sprague-Dawley rat aorta. We conclude that acrolein generation in the blood vessel wall increases human susceptibility to vasospasm, an event that is enhanced in hypertension.

  1. Acrolein generation stimulates hypercontraction in isolated human blood vessels

    PubMed Central

    Conklin, D.J.; Bhatnagar, A.; Cowley, H.R.; Johnson, G.H.; Wiechmann, R.J.; Sayre, L.M.; Trent, M.B.; Boor, P.J.

    2012-01-01

    Increased risk of vasospasm, a spontaneous hyperconstriction, is associated with atherosclerosis, cigarette smoking, and hypertension—all conditions involving oxidative stress, lipid peroxidation, and inflammation. To test the role of the lipid peroxidation- and inflammation-derived aldehyde, acrolein, in human vasospasm, we developed an ex vivo model using human coronary artery bypass graft (CABG) blood vessels and a demonstrated acrolein precursor, allylamine. Allylamine induces hypercontraction in isolated rat coronary artery in a semicarbazide-sensitive amine oxidase activity (SSAO) dependent manner. Isolated human CABG blood vessels (internal mammary artery, radial artery, saphenous vein) were used to determine: (1) vessel responses and sensitivity to acrolein, allylamine, and H2O2 exposure (1 μM–1 mM), (2) SSAO dependence of allylamine-induced effects using SSAO inhibitors (semicarbazide, 1 mM; MDL 72274-E, active isomer; MDL 72274-Z, inactive isomer; 100 μM), (3) the vasoactive effects of two other SSAO amine substrates, benzylamine and methylamine, and (4) the contribution of extracellular Ca2+ to hypercontraction. Acrolein or allylamine but not H2O2, benzylamine, or methylamine stimulated spontaneous and pharmacologically intractable hypercontraction in CABG blood vessels that was similar to clinical vasospasm. Allylamine-induced hypercontraction and blood vessel SSAO activity were abolished by pretreatment with semicarbazide or MDL 72274-E but not by MDL 72274-Z. Allylamine-induced hypercontraction also was significantly attenuated in Ca2+-free buffer. In isolated aorta of spontaneously hypertensive rat, allylamine-induced an SSAO-dependent contraction and enhanced norepinephrine sensitivity but not in Sprague–Dawley rat aorta. We conclude that acrolein generation in the blood vessel wall increases human susceptibility to vasospasm, an event that is enhanced in hypertension. PMID:17095030

  2. Collapsible Cryogenic Storage Vessel Project

    NASA Technical Reports Server (NTRS)

    Fleming, David C.

    2002-01-01

    Collapsible cryogenic storage vessels may be useful for future space exploration missions by providing long-term storage capability using a lightweight system that can be compactly packaged for launch. Previous development efforts have identified an 'inflatable' concept as most promising. In the inflatable tank concept, the cryogen is contained within a flexible pressure wall comprised of a flexible bladder to contain the cryogen and a fabric reinforcement layer for structural strength. A flexible, high-performance insulation jacket surrounds the vessel. The weight of the tank and the cryogen is supported by rigid support structures. This design concept is developed through physical testing of a scaled pressure wall, and through development of tests for a flexible Layered Composite Insulation (LCI) insulation jacket. A demonstration pressure wall is fabricated using Spectra fabric for reinforcement, and burst tested under noncryogenic conditions. An insulation test specimens is prepared to demonstrate the effectiveness of the insulation when subject to folding effects, and to examine the effect of compression of the insulation under compressive loading to simulate the pressure effect in a nonrigid insulation blanket under the action atmospheric pressure, such as would be seen in application on the surface of Mars. Although pressure testing did not meet the design goals, the concept shows promise for the design. The testing program provides direction for future development of the collapsible cryogenic vessel concept.

  3. Wall shear stress exposure time: a Lagrangian measure of near-wall stagnation and concentration in cardiovascular flows.

    PubMed

    Arzani, Amirhossein; Gambaruto, Alberto M; Chen, Guoning; Shadden, Shawn C

    2017-06-01

    Near-wall transport is of utmost importance in connecting blood flow mechanics with cardiovascular disease progression. The near-wall region is the interface for biologic and pathophysiologic processes such as thrombosis and atherosclerosis. Most computational and experimental investigations of blood flow implicitly or explicitly seek to quantify hemodynamics at the vessel wall (or lumen surface), with wall shear stress (WSS) quantities being the most common descriptors. Most WSS measures are meant to quantify the frictional force of blood flow on the vessel lumen. However, WSS also provides an approximation to the near-wall blood flow velocity. We herein leverage this fact to compute a wall shear stress exposure time (WSSET) measure that is derived from Lagrangian processing of the WSS vector field. We compare WSSET against the more common relative residence time (RRT) measure, as well as a WSS divergence measure, in several applications where hemodynamics are known to be important to disease progression. Because these measures seek to quantify near-wall transport and because near-wall transport is important in several cardiovascular pathologies, surface concentration computed from a continuum transport model is used as a reference. The results show that compared to RRT, WSSET is able to better approximate the locations of near-wall stagnation and concentration build-up of chemical species, particularly in complex flows. For example, the correlation to surface concentration increased on average from 0.51 (RRT) to 0.79 (WSSET) in abdominal aortic aneurysm flow. Because WSSET considers integrated transport behavior, it can be more suitable in regions of complex hemodynamics that are traditionally difficult to quantify, yet encountered in many disease scenarios.

  4. OCT assessment of aortic wall degradation for surgical guidance

    NASA Astrophysics Data System (ADS)

    Real, E.; Val-Bernal, J. F.; Pontón, A.; Calvo Díez, M.; Mayorga, M.; Revuelta, J. M.; López-Higuera, J. M.; Conde, O. M.

    2014-05-01

    The degradation of the wall in large cardiovascular vessels, such as the aorta artery, induces weakness in the vessel that can lead to the formation of aneurysms and the rupture of the vessel. Characterization of the wall integrity is assessed by OCT for future intraoperative assistance in aneurysm graft surgery interventions. Optical Coherence Tomography (OCT) provides cross sectional images of the wall of the aortic media layer. Wall degradations appear as spatial anomalies in the reflectivity profile through the wall thickness. Wall degradation assessment is proposed by automatic identification and dimensioning of these anomalies within the homogeneous surrounding tissue.

  5. VCAM-1 expression on dystrophic muscle vessels has a critical role in the recruitment of human blood-derived CD133+ stem cells after intra-arterial transplantation.

    PubMed

    Gavina, Manuela; Belicchi, Marzia; Rossi, Barbara; Ottoboni, Linda; Colombo, Fabio; Meregalli, Mirella; Battistelli, Maurizio; Forzenigo, Laura; Biondetti, Piero; Pisati, Federica; Parolini, Daniele; Farini, Andrea; Issekutz, Andrew C; Bresolin, Nereo; Rustichelli, Franco; Constantin, Gabriela; Torrente, Yvan

    2006-10-15

    Recently our group demonstrated the myogenic capacity of human CD133(+) cells isolated from peripheral blood when delivered in vivo through the arterial circulation into the muscle of dystrophic scid/mdx mice. CD133(+) stem cells express the adhesion molecules CD44, LFA-1, PSGL-1, alpha4-integrins, L-selectin, and chemokine receptor CCR7. Moreover these cells adhere in vitro to VCAM-1 spontaneously and after stimulation with CCL19. Importantly, after muscle exercise, we found that the expression of VCAM-1 is strongly up-regulated in dystrophic muscle vessels, whereas the number of rolling and firmly adhered CD133(+) stem cells significantly increased. Moreover, human dystrophin expression was significantly increased when muscle exercise was performed 24 hours before the intra-arterial injection of human CD133(+) cells. Finally, treatment of exercised dystrophic mice with anti-VCAM-1 antibodies led to a dramatic blockade of CD133(+) stem cell migration into the dystrophic muscle. Our results show for the first time that the expression of VCAM-1 on dystrophic muscle vessels induced by exercise controls muscle homing of human CD133(+) stem cells, opening new perspectives for a potential therapy of muscular dystrophy based on the intra-arterial delivery of CD133(+) stem cells.

  6. A New Mechanism for the Regulation of Stomatal Aperture Size in Intact Leaves (Accumulation of Mesophyll-Derived Sucrose in the Guard-Cell Wall of Vicia faba).

    PubMed

    Lu, P.; Outlaw Jr, W. H.; Smith, B. G.; Freed, G. A.

    1997-05-01

    At various times after pulse-labeling broad bean (Vicia faba L.) leaflets with 14CO2, whole-leaf pieces and rinsed epidermal peels were harvested and subsequently processed for histochemical analysis. Cells dissected from whole leaf retained apoplastic contents, whereas those from rinsed peels contained only symplastic contents. Sucrose (Suc)-specific radioactivity peaked (111 GBq mol-1) in palisade cells at 20 min. In contrast, the 14C content and Sucspecific radioactivity were very low in guard cells for 20 min, implying little CO2 incorporation; both then peaked at 40 min. The guard-cell apoplast had a high maximum Suc-specific radioactivity (204 GBq mol-1) and a high Suc influx rate (0.05 pmol stoma-1 min-1). These and other comparisons implied the presence of (a) multiple Suc pools in mesophyll cells, (b) a localized mesophyll-apoplast region that exchanges with phloem and stomata, and (c) mesophyll-derived Suc in guard-cell walls sufficient to diminish stomatal opening by approximately 3 [mu]m. Factors expected to enhance Suc accumulation in guard-cell walls are (a) high transpiration rate, which closes stomata, and (b) high apoplastic Suc concentration, which is elevated when mesophyll Suc efflux exceeds translocation. Therefore, multiple physiological factors are integrated in the attenuation of stomatal aperture size by this previously unrecognized mechanism.

  7. A new mechanism for the regulation of stomatal aperture size in intact leaves: Accumulation of mesophyll-derived sucrose in the guard-cell wall of Vicia faba

    SciTech Connect

    Lu, Ping; Outlaw, W.H. Jr.; Smith, B.G.; Freed, G.A.

    1997-05-01

    At various times after pulse-labeling broad bean (Vicia faba L.) leaflets with {sup 14}CO{sub 2}, whole-leaf pieces and rinsed epidermal peels were harvested and subsequently processed for histochemical analysis. Cells dissected from whole leaf retained apoplastic contents, whereas those from rinsed peels contained only symplastic contents. Sucrose (Suc)-specific radioactivity peaked (111 GBq mol{sup -1}) in palisade cells at 20 min. In contrast, the {sup 14}C content and Suc-specific radioactivity were very low in guard cells for 20 min, implying little CO, incorporation; both then peaked at 40 min. The guard-cell apoplast had a high maximum Suc-specific radioactivity (204 GBq mol{sup -1}) and a high Suc influx rate (0.05 pmol stoma{sup -1} min{sup -1}). These and other comparisons implied the presence of (a) multiple Suc pools in mesophyll cells, M a localized mesophyll-apoplast region that exchanges with phloem and stomata, and mesophyll-derived Suc in guard-cell walls sufficient to diminish stomatal opening by approximately 3 pm. Factors expected to enhance Suc accumulation in guard-cell walls are (a) high transpiration rate, which closes stomata, and N high apoplastic Suc concentration, which is elevated when mesophyll Suc efflux exceeds translocation. Therefore, multiple physiological factors are integrated in the attenuation of stomatal aperture size by this previously unrecognized mechanism. 50 refs., 9 figs.

  8. Simple benzene derivatives adsorption on defective single-walled carbon nanotubes: a first-principles van der Waals density functional study.

    PubMed

    Ganji, Masoud Darvish; Mohseni, Maryam; Bakhshandeh, Anahita

    2013-03-01

    We have investigated the interaction between open-ended zig-zag single-walled carbon nanotube (SWCNT) and a few benzene derivatives using the first-principles van der Waals density functional (vdW-DF) method, involving full geometry optimization. Such sp (2)-like materials are typically investigated using conventional DFT methods, which significantly underestimate non-local dispersion forces (vdW interactions), therefore affecting interactions between respected molecules. Here, we considered the vdW forces for the interacting molecules that originate from the interacting π electrons of the two systems. The -0.54 eV adsorption energy reveals that the interaction of benzene with the side wall of the SWCNT is typical of the strong physisorption and comparable with the experimental value for benzene adsorption onto the graphene sheet. It was found that aromatics are physisorbed on the sidewall of perfect SWCNTs, as well as at the edge site of the defective nanotube. Analysis of the electronic structures shows that no orbital hybridization between aromatics and nanotubes occurs in the adsorption process. The results are relevant in order to identify the potential applications of noncovalent functionalized systems.

  9. 5. VIEW, LOOKING NORTH, SHOWING REAR WALL, CLEAT AND SINGLE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    5. VIEW, LOOKING NORTH, SHOWING REAR WALL, CLEAT AND SINGLE BIT ON STERN DECK OF VESSEL 37 Edward Larrabee, photographer, December 1984 - Shooters Island, Ships Graveyard, Vessel No. 37, Newark Bay, Staten Island (subdivision), Richmond County, NY

  10. Unique phagocytic properties of hemocytes of Pacific oyster Crassostrea gigas against yeast and yeast cell-wall derivatives.

    PubMed

    Takahashi, Keisuke G; Izumi-Nakajima, Nakako; Mori, Katsuyoshi

    2017-09-09

    For a marine bivalve mollusk such as Pacific oyster Crassostrea gigas, the elimination of foreign particles via hemocyte phagocytosis plays an important role in host defense mechanisms. The hemocytes of C. gigas have a high phagocytic ability for baker's yeast (Saccharomyces cerevisiae) and its cell-wall product zymosan. C. gigas hemocytes might phagocytose yeast cells after binding to polysaccharides on the cell-wall surface, but it is unknown how and what kinds of polysaccharide molecules are recognized. We conducted experiments to determine differences in the phagocytic ability of C. gigas hemocytes against heat-killed yeast (HK yeast), zymosan and zymocel, which are similarly sized and shaped but differ in the polysaccharide composition of their particle surface. We found that both the agranulocytes and granulocytes exerted strong phagocytic ability on all tested particles. The phagocytic index (PI) of granulocytes for zymosan was 9.4 ± 1.7, which significantly differed with that for HK yeast and zymocel (P < 0.05). To evaluate the PI for the three types of particles, and especially to understand the outcome of the much higher PI for zymosan, PI was gauged in increments of 5 (1-5, 6-10, 11-15, and ≥16), and the phagocytic frequencies were compared according to these increments. The results show that a markedly high PI of ≥16 was exhibited by 18.1% of granulocytes for zymosan, significantly higher than 1.7% and 3.9% shown for HK yeast and zymocel, respectively (P < 0.05). These findings indicate that the relatively high PI for zymosan could not be attributed to a situation wherein all phagocytic hemocytes shared a high mean PI, but rather to the ability of some hemocytes to phagocytose a larger portion of zymosan. To determine whether the phagocytosis of these respective particles depended on the recognition of specific polysaccharide receptors on the hemocyte surface, C. gigas hemocytes were pretreated with soluble α-mannan or β-laminarin and

  11. 40 CFR 63.120 - Storage vessel provisions-procedures to determine compliance.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... uniform probe passes freely (without forcing or binding against the seal) between the seal and the wall of... determined by using probes of various widths to measure accurately the actual distance from the vessel wall... it completely covers the space between the roof edge and the vessel wall except as provided...

  12. Nuclear reactor construction with bottom supported reactor vessel

    DOEpatents

    Sharbaugh, John E.

    1987-01-01

    An improved liquid metal nuclear reactor construction has a reactor core and a generally cylindrical reactor vessel for holding a large pool of low pressure liquid metal coolant and housing the core within the pool. The reactor vessel has an open top end, a closed flat bottom end wall and a continuous cylindrical closed side wall interconnecting the top end and bottom end wall. The reactor also has a generally cylindrical concrete containment structure surrounding the reactor vessel and being formed by a cylindrical side wall spaced outwardly from the reactor vessel side wall and a flat base mat spaced below the reactor vessel bottom end wall. A central support pedestal is anchored to the containment structure base mat and extends upwardly therefrom to the reactor vessel and upwardly therefrom to the reactor core so as to support the bottom end wall of the reactor vessel and the lower end of the reactor core in spaced apart relationship above the containment structure base mat. Also, an annular reinforced support structure is disposed in the reactor vessel on the bottom end wall thereof and extends about the lower end of the core so as to support the periphery thereof. In addition, an annular support ring having a plurality of inward radially extending linear members is disposed between the containment structure base mat and the bottom end of the reactor vessel wall and is connected to and supports the reactor vessel at its bottom end on the containment structure base mat so as to allow the reactor vessel to expand radially but substantially prevent any lateral motions that might be imposed by the occurrence of a seismic event. The reactor construction also includes a bed of insulating material in sand-like granular form, preferably being high density magnesium oxide particles, disposed between the containment structure base mat and the bottom end wall of the reactor vessel and uniformly supporting the reactor vessel at its bottom end wall on the containment

  13. Molten metal containment vessel with rare earth oxysulfide protective coating thereon and method of making same

    DOEpatents

    Krikorian, Oscar H.; Curtis, Paul G.

    1992-01-01

    An improved molten metal containment vessel is disclosed in which wetting of the vessel's inner wall surfaces by molten metal is inhibited by coating at least the inner surfaces of the containment vessel with one or more rare earth oxysulfide or rare earth sulfide compounds to inhibit wetting and or adherence by the molten metal to the surfaces of the containment vessel.

  14. Smooth muscle–endothelial cell communication activates Reelin signaling and regulates lymphatic vessel formation

    PubMed Central

    Lutter, Sophie; Xie, Sherry; Tatin, Florence

    2012-01-01

    Active lymph transport relies on smooth muscle cell (SMC) contractions around collecting lymphatic vessels, yet regulation of lymphatic vessel wall assembly and lymphatic pumping are poorly understood. Here, we identify Reelin, an extracellular matrix glycoprotein previously implicated in central nervous system development, as an important regulator of lymphatic vascular development. Reelin-deficient mice showed abnormal collecting lymphatic vessels, characterized by a reduced number of SMCs, abnormal expression of lymphatic capillary marker lymphatic vessel endothelial hyaluronan receptor 1 (LYVE-1), and impaired function. Furthermore, we show that SMC recruitment to lymphatic vessels stimulated release and proteolytic processing of endothelium-derived Reelin. Lymphatic endothelial cells in turn responded to Reelin by up-regulating monocyte chemotactic protein 1 (MCP1) expression, which suggests an autocrine mechanism for Reelin-mediated control of endothelial factor expression upstream of SMC recruitment. These results uncover a mechanism by which Reelin signaling is activated by communication between the two cell types of the collecting lymphatic vessels—smooth muscle and endothelial cells—and highlight a hitherto unrecognized and important function for SMCs in lymphatic vessel morphogenesis and function. PMID:22665518

  15. [Fluid studies on flow behaviour in narrowing vessels with PC-velocimetry and numerical simulations].

    PubMed

    Lehmpfuhl, Monika; Hao, Chongyang; Martirosian, Petros; Schick, Fritz

    2009-02-01

    Fluid dynamics play an important role in arterial diseases. PC-velocimetry as a magnetic resonance (MR) method is a useful tool for the examination of blood vessels, in particular in haemodynamics and morphology. Due to signal loss caused by turbulent flow, classification of stenoses remains difficult. In the presence of metallic stents, susceptibility effects and RF-artefacts further deteriorate image quality. Regarding fluid dynamics, stenosis, stent and restenosis (i.e., re-closing of the vessel in areas with stents) have similar properties: the flow close to an obstacle is accelerated and after a specific length, the so-called reattachment length, it redevelops into its original flow profile. Depending on the shape of the obstacle and its reattachment length, a method is developed to classify stenosis using MR-imaging. Enlarged, simplified stenosis models (phantoms) were examined and were also modelled using computational fluid dynamics (CFD). MR- and CFD-measurements show influences of the stenosis shape, especially the diameter. In graphical analysis (streamline and vector plots), a reattachment length of 6.7xstep size could be determined under laminar conditions and nonpulsatile flow. Stenosis and other narrowing of vessels are classifiable more exactly using PC-velocimetry. From the flow behaviour in the area around the narrowing of the vessel wall, the character of the stenosis can be derived. But more parameters, as bended vessel shapes, pulsated flow, non-Newtonian flow behaviour as well as elastic properties of the vessels need to be incorporated.

  16. Vascular smooth muscle progenitor cells: building and repairing blood vessels.

    PubMed

    Majesky, Mark W; Dong, Xiu Rong; Regan, Jenna N; Hoglund, Virginia J

    2011-02-04

    Molecular pathways that control the specification, migration, and number of available smooth muscle progenitor cells play key roles in determining blood vessel size and structure, capacity for tissue repair, and progression of age-related disorders. Defects in these pathways produce malformations of developing blood vessels, depletion of smooth muscle progenitor cell pools for vessel wall maintenance and repair, and aberrant activation of alternative differentiation pathways in vascular disease. A better understanding of the molecular mechanisms that uniquely specify and maintain vascular smooth muscle cell precursors is essential if we are to use advances in stem and progenitor cell biology and somatic cell reprogramming for applications directed to the vessel wall.

  17. Reactor vessel lower head integrity

    SciTech Connect

    Rubin, A.M.

    1997-02-01

    On March 28, 1979, the Three Mile Island Unit 2 (TMI-2) nuclear power plant underwent a prolonged small break loss-of-coolant accident that resulted in severe damage to the reactor core. Post-accident examinations of the TMI-2 reactor core and lower plenum found that approximately 19,000 kg (19 metric tons) of molten material had relocated onto the lower head of the reactor vessel. Results of the OECD TMI-2 Vessel Investigation Project concluded that a localized hot spot of approximately 1 meter diameter had existed on the lower head. The maximum temperature on the inner surface of the reactor pressure vessel (RPV) in this region reached 1100{degrees}C and remained at that temperature for approximately 30 minutes before cooling occurred. Even under the combined loads of high temperature and high primary system pressure, the TMI-2 RPV did not fail. (i.e. The pressure varied from about 8.5 to 15 MPa during the four-hour period following the relocation of melt to the lower plenum.) Analyses of RPV failure under these conditions, using state-of-the-art computer codes, predicted that the RPV should have failed via local or global creep rupture. However, the vessel did not fail; and it has been hypothesized that rapid cooling of the debris and the vessel wall by water that was present in the lower plenum played an important role in maintaining RPV integrity during the accident. Although the exact mechanism(s) of how such cooling occurs is not known, it has been speculated that cooling in a small gap between the RPV wall and the crust, and/or in cracks within the debris itself, could result in sufficient cooling to maintain RPV integrity. Experimental data are needed to provide the basis to better understand these phenomena and improve models of RPV failure in severe accident codes.

  18. Nuclear reactor vessel fuel thermal insulating barrier

    DOEpatents

    Keegan, C. Patrick; Scobel, James H.; Wright, Richard F.

    2013-03-19

    The reactor vessel of a nuclear reactor installation which is suspended from the cold leg nozzles in a reactor cavity is provided with a lower thermal insulating barrier spaced from the reactor vessel that has a hemispherical lower section that increases in volume from the center line of the reactor to the outer extent of the diameter of the thermal insulating barrier and smoothly transitions up the side walls of the vessel. The space between the thermal insulating harrier and the reactor vessel forms a chamber which can be flooded with cooling water through passive valving to directly cool the reactor vessel in the event of a severe accident. The passive inlet valve for the cooling water includes a buoyant door that is normally maintained sealed under its own weight and floats open when the cavity is Hooded. Passively opening steam vents are also provided.

  19. Wall of fundamental constants

    SciTech Connect

    Olive, Keith A.; Peloso, Marco; Uzan, Jean-Philippe

    2011-02-15

    We consider the signatures of a domain wall produced in the spontaneous symmetry breaking involving a dilatonlike scalar field coupled to electromagnetism. Domains on either side of the wall exhibit slight differences in their respective values of the fine-structure constant, {alpha}. If such a wall is present within our Hubble volume, absorption spectra at large redshifts may or may not provide a variation in {alpha} relative to the terrestrial value, depending on our relative position with respect to the wall. This wall could resolve the contradiction between claims of a variation of {alpha} based on Keck/Hires data and of the constancy of {alpha} based on Very Large Telescope data. We derive the properties of the wall and the parameters of the underlying microscopic model required to reproduce the possible spatial variation of {alpha}. We discuss the constraints on the existence of the low-energy domain wall and describe its observational implications concerning the variation of the fundamental constants.

  20. The Degree of Nonlinearity and Anisotropy of Blood Vessel Elasticity

    NASA Astrophysics Data System (ADS)

    Zhou, J.; Fung, Y. C.

    1997-12-01

    Blood vessel elasticity is important to physiology and clinical problems involving surgery, angioplasty, tissue remodeling, and tissue engineering. Nonlinearity in blood vessel elasticity in vivo is important to the formation of solitons in arterial pulse waves. It is well known that the stress-strain relationship of the blood vessel is nonlinear in general, but a controversy exists on how nonlinear it is in the physiological range. Another controversy is whether the vessel wall is biaxially isotropic. New data on canine aorta were obtained from a biaxial testing machine over a large range of finite strains referred to the zero-stress state. A new pseudo strain energy function is used to examine these questions critically. The stress-strain relationship derived from this function represents the sum of a linear stress-strain relationship and a definitely nonlinear relationship. This relationship fits the experimental data very well. With this strain energy function, we can define a parameter called the degree of nonlinearity, which represents the fraction of the nonlinear strain energy in the total strain energy per unit volume. We found that for the canine aorta, the degree of nonlinearity varies from 5% to 30%, depending on the magnitude of the strains in the physiological range. In the case of canine pulmonary artery in the arch region, Debes and Fung [Debes, J. C. & Fung, Y. C.(1995) Am. J. Physiol. 269, H433-H442] have shown that the linear regime of the stress-strain relationship extends from the zero-stress state to the homeostatic state and beyond. Both vessels, however, are anisotropic in both the linear and nonlinear regimes.

  1. Quantification of carotid vessel atherosclerosis

    NASA Astrophysics Data System (ADS)

    Chiu, Bernard; Egger, Micaela; Spence, J. D.; Parraga, Grace; Fenster, Aaron

    2006-03-01

    Atherosclerosis is characterized by the development of plaques in the arterial wall, which ultimately leads to heart attacks and stroke. 3D ultrasound (US) has been used to screen patients' carotid arteries. Plaque measurements obtained from these images may aid in the management and monitoring of patients, and in evaluating the effect of new treatment options. Different types of measures for ultrasound phenotypes of atherosclerosis have been proposed. Here, we report on the development and application of a method used to analyze changes in carotid plaque morphology from 3D US images obtained at two different time points. We evaluated our technique using manual segmentations of the wall and lumen of the carotid artery from images acquired in two US scanning sessions. To incorporate the effect of intraobserver variability in our evaluation, manual segmentation was performed five times each for the arterial wall and lumen. From this set of five segmentations, the mean wall and lumen surfaces were reconstructed, with the standard deviation at each point mapped onto the surfaces. A correspondence map between the mean wall and lumen surfaces was then established, and the thickness of the atherosclerotic plaque at each point in the vessel was estimated to be the distance between each correspondence pairs. The two-sample Student's t-test was used to judge whether the difference between the thickness values at each pair corresponding points of the arteries in the two 3D US images was statistically significant.

  2. Acoustic emission testing of composite vessels under sustained loading

    NASA Technical Reports Server (NTRS)

    Lark, R. F.; Moorhead, P. E.

    1978-01-01

    Acoustic emissions (AE) generated from Kevlar 49/epoxy composite pressure vessels subjected to sustained load-to-failure tests were studied. Data from two different transducer locations on the vessels were compared. It was found that AE from vessel wall-mounted transducers showed a wide variance from those for identical vessels subjected to the same pressure loading. Emissions from boss-mounted transducers did, however, yield values that were relatively consistent. It appears that the signals from the boss-mounted transducers represent an integrated average of the emissions generated by fibers fracturing during the vessel tests. The AE from boss-mounted transducers were also independent of time for vessel failure. This suggests that a similar number of fiber fractures must occur prior to initiation of vessel failure. These studies indicate a potential for developing an AE test procedure for predicting the residual service life or integrity of composite vessels.

  3. The extracellular matrix of blood vessels.

    PubMed

    Eble, Johannes A; Niland, Stephan

    2009-01-01

    Blood vessels are highly organized and complex structure, which are far more than simple tubes conducting the blood to almost any tissue of the body. They are able to autonomously regulate the blood flow, thus providing the tissues an optimal support of oxygen and nutrients and an efficient removal of waste products. In higher organisms, the blood vessel forms a closed circuit system, which additionally has the ability to seal itself in case of leakage as a result of injury. The blood vessel system does not only transport soluble substances, but also serves as "highway" system for leukocytes to patrol the body during the immunological surveillance and to reach the inflammation site quickly. In a complex interplay with the vascular wall, leukocytes are able to penetrate the blood vessel without any obvious leakage. Pathologically, tumor cells subvert the blood vessel system to disseminate from the primary tumor and colonize distant organs during metastasis. The extracellular matrix (ECM) of a blood vessel contributes substantially to the diverse functions of the blood vessel. First, the ECM constitutes the scaffold which keeps the histological structure of the vessel wall in shape but also bears the enormous and permanent mechanical forces levied on the vessel by the pulsatile blood flow in the arteries and by vasoconstriction, which regulates blood flow and pressure. The complex network of elastic fibers and tensile forces-bearing networks are well adapted to accomplish these mechanical tasks. Second, the ECM provides informational cues to the vascular cells, thus regulating their proliferation and differentiation. Third, ECM molecules can store, mask, present or sequester growth factors, thereby modulating their effects remarkably. Furthermore, several ECM molecules serve additional functions within the blood vessel. Their expression is altered in a spatial and temporal pattern during blood vessel formation and remodeling. In contrast to vasculogenesis during

  4. Lymphatic vessels of the human dental pulp in different conditions.

    PubMed

    Marchetti, C; Poggi, P; Calligaro, A; Casasco, A

    1992-09-01

    The characteristics of the lymphatic vessel endothelial wall have been investigated in human normal and inflamed dental pulps. In normal pulps the endothelial wall is characterized by the presence of micropinocytotic vesicles and intraparietal channels. In the inflamed pulpal tissue, where an increase in interstitial fluid pressure occurs, the distended endothelial wall presents open junctions between endothelial cells and the openings of the intraparietal channels. Moreover the micropinocytotic vesicles disappear. The cytoplasm of the endothelial cells is characterized by the presence of numerous Weibel-Palade bodies, which increase in number in the dilated vessels. In the fibrillar apparatus surrounding the lymphatic vessel wall collagen fibrils are the prevalent component, while elastic fibers are not present. The different morphological properties of the lymphatic vessels are compared and discussed with regard to the variation of the functional conditions of the tissue.

  5. Participation of blood vessel cells in human adaptive immune responses.

    PubMed

    Pober, Jordan S; Tellides, George

    2012-01-01

    Circulating T cells contact blood vessels either when they extravasate across the walls of microvessels into inflamed tissues or when they enter into the walls of larger vessels in inflammatory diseases such as atherosclerosis. The blood vessel wall is largely composed of three cell types: endothelial cells lining the entire vascular tree; pericytes supporting the endothelium of microvessels; and smooth muscle cells forming the bulk of large vessel walls. Each of these cell types interacts with and alters the behavior of infiltrating T cells in different ways, making these cells active participants in the processes of immune-mediated inflammation. In this review, we compare and contrast what is known about the nature of these interactions in humans. Copyright © 2011 Elsevier Ltd. All rights reserved.

  6. Potential implications of vascular wall resident endothelial progenitor cells.

    PubMed

    Ergün, Süleyman; Tilki, Derya; Hohn, Hans-Peter; Gehling, Ursula; Kilic, Nerbil

    2007-11-01

    A rapidly increasing body of data suggests an essential role of endothelial progenitor cells (EPCs) in vascular regeneration, formation of new vessels in cardiovascular diseases and also in tumor vasculogenesis. Moreover, recent data obtained from clinical studies with anti-angiogenic drugs in tumor therapy or with pro-angiogenic stimuli in ischemic disorders implicate a predictive role of the number of EPCs circulating in the peripheral blood in monitoring of these diseases. However, there is still some controversial data regarding the relevance of the EPCs in vascular formation depending on models used and diseases studied. One of the essential prerequisites for a better understanding of the whole contribution of EPCs to vascular formation in adult, a process called postnatal vasculogenesis, is to identify their exact sources. We could recently discover the existence of EPCs in a distinct zone of the vascular wall of large and middle sized adult blood vessels and showed that these cells are capable to differentiate into mature endothelial cells, to form capillary sprouts in arterial ring assay and to build vasa vasorum-like structures within the vascular wall. They also can be mobilized very rapidly from the vascular wall by tumor cells. This review will discuss the functional implications of these vascular wall resident endothelial progenitor cells (VW-EPCs) in relation to those of EPCs circulating in peripheral blood or derived from the bone marrow in cardiovascular and neoplastic diseases.

  7. Partitioning of vessel resistivity in three liana species.

    PubMed

    Balaz, Milan; Jupa, Radek; Jansen, Steven; Cobb, Alexander; Gloser, Vít

    2016-12-01

    Vessels with simple perforation plates, found in the majority of angiosperms, are considered the evolutionarily most advanced conduits, least impeding the xylem sap flow. Nevertheless, when measured, their hydraulic resistivity (R, i.e., inverse value of hydraulic conductivity) is significantly higher than resistivity predicted using Hagen-Poiseuille equation (RHP). In our study we aimed (i) to quantify two basic components of the total vessel resistivity - vessel lumen resistivity and end wall resistivity, and (ii) to analyze how the variable inner diameter of the vessel along its longitudinal axis affects resistivity. We measured flow rates through progressively shortened stems of hop (Humulus lupulus L.), grapevine (Vitis vinifera L.), and clematis (Clematis vitalba L.) and used elastomer injection for identification of open vessels and for measurement of changing vessel inner diameters along its axis. The relative contribution of end wall resistivity to total vessel resistivity was 0.46 for hop, 0.55 for grapevine, and 0.30 for clematis. Vessel lumen resistivity calculated from our measurements was substantially higher than theoretical resistivity - about 43% for hop, 58% for grapevine, and 52% for clematis. We identified variation in the vessel inner diameter as an important source of vessel resistivity. The coefficient of variation of vessel inner diameter was a good predictor for the increase of the ratio of integral RHP to RHP calculated from the mean value of inner vessel diameter. We discuss the fact that we dealt with the longest vessels in a given stem sample, which may lead to the overestimation of vessel lumen resistivity, which consequently precludes decision whether the variable vessel inner diameter explains fully the difference between vessel lumen resistivity and RHP we observed.

  8. Thermal Spore Exposure Vessels

    NASA Technical Reports Server (NTRS)

    Beaudet, Robert A.; Kempf, Michael; Kirschner, Larry

    2006-01-01

    Thermal spore exposure vessels (TSEVs) are laboratory containers designed for use in measuring rates of death or survival of microbial spores at elevated temperatures. A major consideration in the design of a TSEV is minimizing thermal mass in order to minimize heating and cooling times. This is necessary in order to minimize the number of microbes killed before and after exposure at the test temperature, so that the results of the test accurately reflect the effect of the test temperature. A typical prototype TSEV (see figure) includes a flat-bottomed stainless-steel cylinder 4 in. (10.16 cm) long, 0.5 in. (1.27 cm) in diameter, having a wall thickness of 0.010 plus or minus 0.002 in. (0.254 plus or minus 0.051 mm). Microbial spores are deposited in the bottom of the cylinder, then the top of the cylinder is closed with a sterile rubber stopper. Hypodermic needles are used to puncture the rubber stopper to evacuate the inside of the cylinder or to purge the inside of the cylinder with a gas. In a typical application, the inside of the cylinder is purged with dry nitrogen prior to a test. During a test, the lower portion of the cylinder is immersed in a silicone-oil bath that has been preheated to and maintained at the test temperature. Test temperatures up to 220 C have been used. Because the spores are in direct contact with the thin cylinder wall, they quickly become heated to the test temperature.

  9. BIOASSAY VESSEL FAILURE ANALYSIS

    SciTech Connect

    Vormelker, P

    2008-09-22

    Two high-pressure bioassay vessels failed at the Savannah River Site during a microwave heating process for biosample testing. Improper installation of the thermal shield in the first failure caused the vessel to burst during microwave heating. The second vessel failure is attributed to overpressurization during a test run. Vessel failure appeared to initiate in the mold parting line, the thinnest cross-section of the octagonal vessel. No material flaws were found in the vessel that would impair its structural performance. Content weight should be minimized to reduce operating temperature and pressure. Outer vessel life is dependent on actual temperature exposure. Since thermal aging of the vessels can be detrimental to their performance, it was recommended that the vessels be used for a limited number of cycles to be determined by additional testing.

  10. Analysis of the vibration regimes of vascular walls

    NASA Astrophysics Data System (ADS)

    Kudryashov, A. V.; Rozenblyum, L. A.; Khurlapova, T. V.; Yakhno, V. G.

    1980-11-01

    The theoretical description exposed here can be used for explaining the differences which are sometimes observed between the values of the diastolic pressure derived from direct measurements and those derived from indirect measurements. Nervous and emotional action may alter markedly the mechanical properties of the muscular layer of the wall. In this respect it is important to what side the hysteresis loop in the radiusstress curve will be shifted. If the hysteresis is shifted towards the region of high pressures, then tones will be recorded at higher pi — P l values and, hence, the error in an indirect measurement of the pressure will increase. From this point of view the phenomenon of an "infinite tone" is explained by the dependence of the hysteresis of the radius on the stress on the wall in the pressure range Pdiastwall appear. From the hypothesis proposed it follows that the duration of the main phase of the tone can be used as a parameter characterizing the viscosity of a vascular wall. The rigidity and the mass of a vascular wall can be estimated from the high-frequency phase of the tone (this phase being determined by the resonance characteristics of the vessel). A check of the clinical value of these parameters requires additional investigations.

  11. A Generalized Wall Function

    NASA Technical Reports Server (NTRS)

    Shih, Tsan-Hsing; Povinelli, Louis A.; Liu, Nan-Suey; Potapczuk, Mark G.; Lumley, J. L.

    1999-01-01

    The asymptotic solutions, described by Tennekes and Lumley (1972), for surface flows in a channel, pipe or boundary layer at large Reynolds numbers are revisited. These solutions can be extended to more complex flows such as the flows with various pressure gradients, zero wall stress and rough surfaces, etc. In computational fluid dynamics (CFD), these solutions can be used as the boundary conditions to bridge the near-wall region of turbulent flows so that there is no need to have the fine grids near the wall unless the near-wall flow structures are required to resolve. These solutions are referred to as the wall functions. Furthermore, a generalized and unified law of the wall which is valid for whole surface layer (including viscous sublayer, buffer layer and inertial sublayer) is analytically constructed. The generalized law of the wall shows that the effect of both adverse and favorable pressure gradients on the surface flow is very significant. Such as unified wall function will be useful not only in deriving analytic expressions for surface flow properties but also bringing a great convenience for CFD methods to place accurate boundary conditions at any location away from the wall. The extended wall functions introduced in this paper can be used for complex flows with acceleration, deceleration, separation, recirculation and rough surfaces.

  12. Experimental Study of Interactions Between Sub-oxidized Corium and Reactor Vessel Steel

    SciTech Connect

    Bechta, S.V.; Khabensky, V.B.; Granovsky, V.S.; Krushinov, E.V.; Vitol, S.A.; Gusarov, V.V.; Almiashev, V.I.; Bottomley, D.; Fischer, M.; Piluso, P.; Fichoti, F.

    2006-07-01

    One of the critical factors in the analysis of in-vessel melt retention is the vessel strength. It is, in particular, sensitive to the thickness of intact vessel wall, which, in its turn, depends on the thermal conditions and physicochemical interactions with corium. Physicochemical interaction of prototypic UO{sub 2}-ZrO{sub 2}-Zr corium melt and VVER vessel steel was examined during the 2. Phase of the ISTC METCOR Project. Rasplav-3 test facility was used for conducting four tests, in which the Zr oxidation degree and interaction front temperature were varied; in one of the tests, stainless steel was added to the melt. Direct experimental measurements and post-test analyses were used for determining corrosion kinetics and maximum corrosion depth (i.e. the physicochemical impact of corium on the cooled vessel steel specimens), as well as the steel temperature conditions during the interaction, and finally the structure and composition of crystallized ingots, including the interaction zone. The minimum temperature on the interaction front boundary, which determined its final position and maximum corrosion depth was {approx} 1090 deg. C. An empirical correlation for calculation of corrosion kinetics has been derived. (authors)

  13. Lymphatic vessels in inflamed human dental pulp.

    PubMed

    Marchetti, C; Piacentini, C; Menghini, P

    1990-01-01

    Investigation has been performed on both the light and electron microscopic characteristics of the lymphatic vessels present in the dental pulp of human teeth which have been affected by serious carious lesions. These conditions provoke a severe inflammatory response resulting in structural and functional modifications of the tissue; increase of the tissue pressure is followed by the need for a more intensive lymphatic drainage. In the inflamed pulps, dilated lymphatic vessels with distended walls and "open junctions" between endothelial cells are detectable. On the other hand they lack certain endothelial structures which characterize the morphology of these vessels under normal conditions. In the pulpal regions affected by fibrotic proliferation shrunken vessels with irregular profiles are present. From these observations it is possible to obtain other information on the mechanisms regulating the lymphatic drainage in different structural and functional conditions of the interstitium.

  14. Probabilistic retinal vessel segmentation

    NASA Astrophysics Data System (ADS)

    Wu, Chang-Hua; Agam, Gady

    2007-03-01

    Optic fundus assessment is widely used for diagnosing vascular and non-vascular pathology. Inspection of the retinal vasculature may reveal hypertension, diabetes, arteriosclerosis, cardiovascular disease and stroke. Due to various imaging conditions retinal images may be degraded. Consequently, the enhancement of such images and vessels in them is an important task with direct clinical applications. We propose a novel technique for vessel enhancement in retinal images that is capable of enhancing vessel junctions in addition to linear vessel segments. This is an extension of vessel filters we have previously developed for vessel enhancement in thoracic CT scans. The proposed approach is based on probabilistic models which can discern vessels and junctions. Evaluation shows the proposed filter is better than several known techniques and is comparable to the state of the art when evaluated on a standard dataset. A ridge-based vessel tracking process is applied on the enhanced image to demonstrate the effectiveness of the enhancement filter.

  15. On-line monitoring and analysis of reactor vessel integrity

    SciTech Connect

    Ackerson, D.S.; Impink, A.J. Jr.; Balkey, K.R.; Andreychek, T.S.

    1989-01-31

    A method is described for on-line monitoring and analysis of nuclear reactor pressure vessel integrity in a unit in which reactor coolant is circulated along the inner wall of the pressure vessel, the method comprising the steps of: generating on an on-line basis, temperature signals representative of the temperature of the reactor coolant circulating along the inner wall of the pressure vessel; generating on an on-line basis, a pressure signal representative of the reactor coolant pressure; generating a signal representative of fast neutron fluence to which the reactor pressure vessel has been subjected; generating as a function of the fluence signal a visual representation of the actual real time reference nil-ductibility transition temperature (RT/sub ndt/) across the entire pressure vessel wall thickness at a preselected critical location in the wall; generating as a function of transients in the reactor coolant temperature and pressur signals, a visual representation of the real time required RT/sub ndt/, across the entire pressure vessel wall thickness at the selected critical location, the required RT/sub ndt/ being the RT/sub ndt/ that would be required in the pressure vessel wall for flaw initiation to occur as a result of stresses set-up by the transients; and superimposing the visual representations of the real-time actual and required RT/sub ndt's/ for flaw initiation across the entire pressure vessel wall thickness for the selected critical location to generate a visual representation of the difference in value between the actual and required RT/sub ndt/ presented as an RT/sub ndt/ margin.

  16. Effects of Wall Distensibility in Hemodynamic Simulations of an Arteriovenous Fistula

    PubMed Central

    McGah, Patrick M.; Leotta, Daniel F.; Beach, Kirk W.; Aliseda, Alberto

    2013-01-01

    Arteriovenous fistulae are created surgically to provide adequate access for dialysis patients suffering from end-stage renal disease. It has long been hypothesized that the rapid blood vessel remodeling occurring after fistula creation is in part a process to restore the mechanical stresses to some preferred level, i.e. mechanical homeostasis. The current study presents fluid-structure interaction (FSI) simulations of a patient-specific model of a mature arteriovenous fistula reconstructed from 3D ultrasound scans. The FSI results are compared with previously published data of the same model but with rigid walls. Ultrasound-derived wall motion measurements are also used to validate the FSI simulations of the wall motion. Very large time-averaged shear stresses, 10–15 Pa, are calculated at the fistula anastomosis in the FSI simulations, values which are much larger than what is typically thought to be the normal homeostatic shear stress in the peripheral vasculature. Although this result is systematically lower by as much as 50% compared to the analogous rigid-walled simulations, the inclusion of distensible vessel walls in hemodynamic simulations does not reduce the high anastomotic shear stresses to “normal” values. Therefore, rigid-walled analyses may be acceptable for identifying high shear regions of arteriovenous fistulae. PMID:24037281

  17. Effects of wall distensibility in hemodynamic simulations of an arteriovenous fistula.

    PubMed

    McGah, Patrick M; Leotta, Daniel F; Beach, Kirk W; Aliseda, Alberto

    2014-06-01

    Arteriovenous fistulae are created surgically to provide adequate access for dialysis patients suffering from end-stage renal disease. It has long been hypothesized that the rapid blood vessel remodeling occurring after fistula creation is in part a process to restore the mechanical stresses to some preferred level, i.e., mechanical homeostasis. The current study presents fluid-structure interaction (FSI) simulations of a patient-specific model of a mature arteriovenous fistula reconstructed from 3D ultrasound scans. The FSI results are compared with previously published data of the same model but with rigid walls. Ultrasound-derived wall motion measurements are also used to validate the FSI simulations of the wall motion. Very large time-averaged shear stresses, 10-15 Pa, are calculated at the fistula anastomosis in the FSI simulations, values which are much larger than what is typically thought to be the normal homeostatic shear stress in the peripheral vasculature. Although this result is systematically lower by as much as 50% compared to the analogous rigid-walled simulations, the inclusion of distensible vessel walls in hemodynamic simulations does not reduce the high anastomotic shear stresses to "normal" values. Therefore, rigid-walled analyses may be acceptable for identifying high shear regions of arteriovenous fistulae.

  18. Wall turbulence without walls

    NASA Astrophysics Data System (ADS)

    Mizuno, Yoshinori; Jimenez, Javier

    2008-11-01

    Direct numerical simulations are presented of isolated logarithmic layers without an underlying buffer zone. They are implemented by enforcing artificial boundary conditions within the logarithmic layer which are synthesized from values from the interior of the flow. As an example, simulations of a half-channel employing this technique are discussed. The results exhibit logarithmic mean velocity profiles, and velocity fluctuation intensities that are similar to those obtained by the full DNS of half or full channels. Those results strongly suggest that the formation of a logarithmic layer is not overly dependent on the presence of a near-wall region, and that such a flow can exist by itself. The technique enables us to perform conceptual experiments to clarify what is essential to the logarithmic layer. For example, preliminary results show that the logarithmic layer cannot be created only by a non-uniform shear, and requires a spatial gradient of the scales of the fluctuations. Somewhat surprisingly, some simulations result in Kármán constants fairly different from κ=0.4, providing clues to what determines κ in real wall turbulence.

  19. Pressure vessel burst test program - Progress paper No. 4

    NASA Technical Reports Server (NTRS)

    Cain, Maurice R.; Sharp, Douglas E.

    1993-01-01

    A status report is presented for a program studying the characteristics of the blast waves and fragmentation caused by ruptured gas-filled pressure vessels. Experimental data trends have been derived from 14 burst pressure vessels. Attention is given to energy release in bursting, blast wave and fragmentation behavior, height of burst effects, fragment velocity vs vessel pressure, and comparative blast effects for spherical/composite vs cylindrical/steel pressure vessels.

  20. Statistical Analysis on Phototaxis of Goldfish in an Experimental Vessel

    NASA Astrophysics Data System (ADS)

    Sato, Tadashi; Terao, Kunio

    1986-10-01

    Phototactic responses of a goldfish in a vessel are discussed according to the experimental results by an optical apparatus connected to a microcomputer. Assuming that the fish performs the lactic response not only to the incident light but the wall of the vessel, one can determine the one-dimensional position distribution of the fish in the light beam as a steady state solution of the telegraph equation with a drift term. It is found that the fish is uniformly attracted to the light source all over the vessel, but attracted to the wall only within a certain distance.

  1. `Sausage string' patterns in blood vessels at high blood pressures

    NASA Astrophysics Data System (ADS)

    Alstrøm, Preben; Eguíluz, Victor M.; Gustafsson, Finn; Holstein-Rathlou, Niels-Henrik

    A new Rayleigh-type instability is proposed to explain the `sausage-string' pattern of alternating constrictions and dialtations formed in blood vessels at high blood pressure conditions. Our theory involves the nonlinear stress-strain characteristics of the vessel wall, and provides predictions for the conditions under which the normal cylindrical geometry of a blood vessel becomes unstable. The theory explains key features observed experimentally, e.g. the limited occurrence of the sausage-string pattern to small arteries and large arterioles, and only in those with small wall-to-lumen ratios.

  2. Flow in Atherosclerotic Blood Vessels

    NASA Astrophysics Data System (ADS)

    Berger, Stanley A.; Stroud, Jenn S.

    2000-11-01

    Atherosclerotic lesions occur in arteries where there are major changes in flow structure, e.g. bifurcations and junctions. The reduction of vessel lumen alters the flow, including the mechanical forces on the walls. We have examined the flow in carotid artery bifurcations with realistic plaque contours. The unsteady, incompressible, Navier-Stokes equations are solved in finite-volume form. Steady and pulsatile flows have been analyzed for laminar and turbulent flows, using for the latter a low-Reynolds number k- ɛ model and a k-ω model. Non-Newtonian viscosity is also considered using a power-law model. In general the very irregular contours of the vessels lead to recirculating regions, strong spatial variations of wall shear stresses, and in some cases, vortex shedding. Even steady inlet flow exhibits fluctuating, unsteady behavior. Neither turbulence models captures all the physics of the flow. The flow, in fact, appears to be transitional and not fully turbulent. For unsteady flow, there are also strong temporal variations of normal and shear stresses, which together with the strong spatial variations, has important implications for the onset and progression of atherosclerotic disease.

  3. Proliferation and maturation of intratumoral blood vessels in women with malignant ovarian tumors assessed with cancer stem cells marker nestin and platelet derived growth factor PDGF-B.

    PubMed

    Czekierdowska, Sylwia; Stachowicz, Norbert; Chróściel, Mieczysław; Czekierdowski, Artur

    2017-01-01

    Platelet-derived growth factor B (PDGF-B) and nestin have been suggested to be useful in the assessment of neoangiogenesis in malignant ovarian masses. We aimed to investigate a possible association of these markers with newly formed microcapillaries and perivascular cells in ovarian tumors. Microvessel density (MVD) and pericytes were studied in 82 women with ovarian neoplasms, including 7 benign cysts, 7 borderline masses, 64 epithelial ovarian cancers and 4 other malignant ovarian tumors. Immunohistochemical staining included antibodies to CD34, PDGF-B and nestin. Median values of CD34-positive and nestin-positive MVD were: 24,5 (range:17-32) and 21 (range: 12-31), respectively. No significant correlation between intratumoral CD-34 positive MVD and nestin-positive MVD was found. Benign and borderline lesions more frequently than malignant tumors displayed low or medium values of nestin-positive MVD (p = 0.01). Histological grading of malignant tumors was associated with nestin-positive MVD (p = 0.01). Nestin expression in tumor cells was not correlated with tumor grade or histological subtype. PDGF-B expression was found in tumor microves-sels in 72% of cases (59/82). High expression of PDGF in pericapillary cells was strongly associated with high expression of this marker in cancer cells (p = 0.007). Significant correlations between PDGF-B and nestin expression in malignant tumor microvessels were also found (p = 0.04). Nestin and PDGF-B expressions were strongly associated with high grade tumors when compared to low grade or benign masses. We conclude that the assessment of PDGF-B and nestin-positive MVD could be used to identify only highly active, angiogenic malignant ovarian masses, where tumor vasculature is formed.

  4. Reproducibility and Inter-Observer Variability of Systolic Blood Flow Velocity and 3D Wall Shear Stress Derived From 4D flow MRI in the Healthy Aorta

    PubMed Central

    van Ooij, Pim; Powell, Alexander L.; Potters, Wouter V.; Carr, James C.; Markl, Michael; Barker, Alex J.

    2016-01-01

    Purpose To investigate the reproducibility and inter-observer variability of 3D aortic velocity vector fields and wall shear stress (WSS) averaged over five systolic timeframes derived from non-contrast 4D-flow-MRI. Methods Fourteen controls underwent test-retest 4D-flow-MRI examinations separated by 16±3 days (resolution=3.0–3.6×2.3–2.6×2.5–2.7mm3; TE/TR/FA=2.5ms/4.9ms/7°; Venc=150cm/s). Two observers was segmented the aorta, and WSS was calculated for both series of scans and both segmentations. Test-retest and inter-observer velocity and WSS vectors were compared on a voxel-by-voxel basis in the aorta and on a regional basis by subdividing the aortas in six segments. Results Test-retest: voxel-by-voxel Bland-Altman analysis revealed small differences (−0.03/−0.02 m/s/Pa), limits of agreement of 0.25 m/s/0.29 Pa and coefficients of variation (CV) of 20% for velocity/WSS. Voxel-by-voxel orthogonal regression analysis showed moderate agreement (Slope: 1.14/1.16, Intraclass Correlation Coefficient (ICC): 0.76/0.67 for velocity/WSS). The regional analysis revealed a CV of 9%/8% and ICC of 0.9/0.9 for velocity/WSS. Inter-observer: voxel-by-voxel difference for WSS was 0, LOA: 0.17/0.19 Pa, CV: 12/13%, slope: 1.01/1.09, ICC: 0.87/0.85 for test/retest. The CV/ICC for WSS in the regional analysis was 4%/1.0 for test and 3%/1.0 for retest. Conclusions Systolic velocity and WSS derived from 4D flow MRI are reproducible between consecutive visits, with low inter-observer variability in healthy volunteers. PMID:26140480

  5. A multilayered microfluidic blood vessel-like structure

    PubMed Central

    Hasan, Anwarul; Paul, Arghya; Memic, Adnan; Khademhosseini, Ali

    2016-01-01

    There is an immense need for tissue engineered blood vessels. However, current tissue engineering approaches still lack the ability to build native blood vessel-like perfusable structures with multi-layered vascular walls. This paper demonstrated a new method to fabricate tri-layer biomimetic blood vessel-like structures on a microfluidic platform using photocrosslinkable gelatin hydrogel. The presented method enables fabrication of physiological blood vessel-like structures with mono-, bi- or tri-layer vascular walls. The diameter of the vessels, the total thickness of the vessel wall and the thickness of each individual layer of the wall were independently controlled. The developed fabrication process is a simple and rapid method, allowing the physical fabrication of the vascular structure in minutes, and the formation of a vascular endothelial cell layer inside the vessels in 3–5 days. The fabricated vascular constructs can potentially be used in numerous applications including drug screening, development of in vitro models for cardiovascular diseases and/or cancer metastasis, and study of vascular biology and mechanobiology. PMID:26256481

  6. Do Xylem Fibers Affect Vessel Cavitation Resistance?1

    PubMed Central

    Jacobsen, Anna L.; Ewers, Frank W.; Pratt, R. Brandon; Paddock, William A.; Davis, Stephen D.

    2005-01-01

    Possible mechanical and hydraulic costs to increased cavitation resistance were examined among six co-occurring species of chaparral shrubs in southern California. We measured cavitation resistance (xylem pressure at 50% loss of hydraulic conductivity), seasonal low pressure potential (Pmin), xylem conductive efficiency (specific conductivity), mechanical strength of stems (modulus of elasticity and modulus of rupture), and xylem density. At the cellular level, we measured vessel and fiber wall thickness and lumen diameter, transverse fiber wall and total lumen area, and estimated vessel implosion resistance using (t/b)h2, where t is the thickness of adjoining vessel walls and b is the vessel lumen diameter. Increased cavitation resistance was correlated with increased mechanical strength (r2 = 0.74 and 0.76 for modulus of elasticity and modulus of rupture, respectively), xylem density (r2 = 0.88), and Pmin (r2 = 0.96). In contrast, cavitation resistance and Pmin were not correlated with decreased specific conductivity, suggesting no tradeoff between these traits. At the cellular level, increased cavitation resistance was correlated with increased (t/b)h2 (r2 = 0.95), increased transverse fiber wall area (r2 = 0.89), and decreased fiber lumen area (r2 = 0.76). To our knowledge, the correlation between cavitation resistance and fiber wall area has not been shown previously and suggests a mechanical role for fibers in cavitation resistance. Fiber efficacy in prevention of vessel implosion, defined as inward bending or collapse of vessels, is discussed. PMID:16100359

  7. Dimensional analysis of blood vessels in the pressure myograph

    NASA Astrophysics Data System (ADS)

    Crabtree, Vincent P.; Smith, Peter R.

    1999-01-01

    The accuracy of conventional and emerging methods for the dimensional analysis of optically imaged arterial vessels, isolated in a pressure myograph, is investigated. The pressure myograph is a device used to study the structure and function of isolated sections of small resistance arteries, as a function of chemical, mechanical and electrical stimuli. The arterial wall and lumen dimensions are particularly important indicators of anatomy and pathology. The conventional method of dimensional analysis uses edge detection, however the accuracy of this approach is questionable when the vessel is in a contracted state since contrast deteriorates or is lost between lumen and vessel wall. The conventional and emerging methods are examined experimentally with vessel phantoms, to provide known characteristics. A novel algorithm, based on a measurement of the vessel extinction coefficient, is also examined theoretically and experimentally. A discussion centers on the possibility for realistic lumen size measurement when edge detection can not be applied and when the accuracy of edge detection is questionable.

  8. Impact damage on shielded gas-filled vessels

    NASA Astrophysics Data System (ADS)

    Schäfer, F.; Schneider, E.; Lambert, M.

    2001-10-01

    This paper gives a summary of the findings from impacts on shielded gas-filled cylindrical aluminium alloy (A12219 T851) and titanium alloy (Ti6A14V) pressure vessels that were performed at the Ernst-Mach-Institute in the frame of an ESA contract. The effect of impacts on shielded vessels with projectiles that have a kinetic energy close to the ballistic limit of the combined system of shield and vessel's front wall was investigated. The shields were single Al-bumper plates, unreinforced MLI and MLI reinforced with 2 layers of Betacloth. The threshold diameters that cause leakage from the vessel's front wall were determined experimentally as a function of shield material and shield spacing. For Al-shielded Al- and Ti-vessels, a safety design factor to avoid leakage is presented based on existing Whipple shield equations.

  9. Correlation between the characteristics of acceleration and visco elasticity of artery wall under pulsatile flow conditions (physical meaning of I* as a parameter of progressive behaviors of atherosclerosis and arteriosclerosis).

    PubMed

    Yokobori, A Toshimitsu; Ohmi, Toshihito; Monma, Ryouhei; Tomono, Yuki; Inoue, Kyousuke; Owa, Michiaki; Ichiki, Masataka; Mochizuki, Noriko; Yamashita, Hidetoshi

    2013-01-01

    Previously, I* parameter has been proposed to diagnose noninvasively the progressive degree of atherosclerosis which is considered to concern the discrimination of the progressive degree of visco elasticity of blood vessel wall. However, the detailed physical meaning of this parameter has not yet been clarified. In this paper, the theoretical analysis and experiments were conducted and the detailed physical meaning of I* parameter was clarified. The following results were obtained. I* parameter was found to well correlate with the progressive degree of visco elasticity of blood vessel wall characterized by the Ith* parameter derived based on the analysis of visco elasticity in this paper. That is, I* was found to have the physical meaning of representing the progressive degree of visco elasticity of blood vessel wall. On the basis of this results, using clinical data, two dimensional representation between the progressive degree of visco elasticity of blood vessel wall by I* and the decrease in the rigidity of blood vessel wall by PWV was found to be useful to conduct much more detailed diagnosis of atherosclerosis.

  10. Instability and ``Sausage-String'' Appearance in Blood Vessels during High Blood Pressure

    NASA Astrophysics Data System (ADS)

    Alstrøm, Preben; Eguíluz, Victor M.; Colding-Jørgensen, Morten; Gustafsson, Finn; Holstein-Rathlou, Niels-Henrik

    1999-03-01

    A new Rayleigh-type instability is proposed to explain the ``sausage-string'' pattern of alternating constrictions and dilatations formed in blood vessels under influence of a vasoconstricting agent. Our theory involves the nonlinear elasticity characteristics of the vessel wall, and provides predictions for the conditions under which the cylindrical form of a blood vessel becomes unstable.

  11. Modeling of blood vessel constriction in 2-D case using molecular dynamics method

    NASA Astrophysics Data System (ADS)

    A. S., M. Rendi; Suprijadi, Viridi, S.

    2014-03-01

    Blood vessel constriction is simulated with particle-based method using a molecular dynamics authoring software known as Molecular Workbench (WM). Blood flow and vessel wall, the only components considered in constructing a blood vessel, are all represented in particle form with interaction potentials: Lennard-Jones potential, push-pull spring potential, and bending spring potential. Influence of medium or blood plasma is accommodated in plasma viscosity through Stokes drag force. It has been observed that pressure p is increased as constriction c is increased. Leakage of blood vessel starts at 80% constriction, which shows existence of maximum pressure that can be overcome by vessel wall.

  12. Identifying new lignin bioengineering targets: impact of epicatechin, quercetin glycoside, and gallate derivatives on the lignification and fermentation of maize cell walls

    USDA-ARS?s Scientific Manuscript database

    Apoplastic targeting of secondary metabolites compatible with monolignol polymerization may provide new avenues for designing lignins that are less inhibitory toward fiber fermentation. To identify suitable monolignol substitutes, we artificially lignified maize cell walls with normal monolignols pl...

  13. Fourier Transform Infrared Spectroscopic Imaging-Derived Collagen Content and Maturity Correlates with Stress in the Aortic Wall of Abdominal Aortic Aneurysm Patients.

    PubMed

    Cheheltani, Rabee; Pichamuthu, Joseph E; Rao, Jayashree; Weinbaum, Justin S; Kiani, Mohammad F; Vorp, David A; Pleshko, Nancy

    2017-03-01

    Abdominal aortic aneurysm (AAA) is a degenerative disease of the aorta characterized by severe disruption of the structural integrity of the aortic wall and its major molecular constituents. From the early stages of disease, elastin in the aorta becomes highly degraded and is replaced by collagen. Questions persist as to the contribution of collagen content, quality and maturity to the potential for rupture. Here, using our recently developed Fourier transform infrared imaging spectroscopy (FT-IRIS) method, we quantified collagen content and maturity in the wall of AAA tissues in pairs of specimens with different wall stresses. CT scans of AAAs from 12 patients were used to create finite element models to estimate stress in different regions of tissue. Each patient underwent elective repair of the AAA, and two segments of the AAA tissues from anatomic regions more proximal or distal with different wall stresses were evaluated by histology and FT-IRIS after excision. For each patient, collagen content was generally greater in the tissue location with lower wall stress, which corresponded to the more distal anatomic regions. The wall stress/collagen ratio was greater in the higher stress region compared to the lower stress region (1.01 ± 1.09 vs. 0.55 ± 0.084, p = 0.02). The higher stress region also corresponded to the location with reduced intraluminal thrombus thickness. Further, collagen maturity tended to decrease with increased collagen content (p = 0.068, R = 0.38). Together, these results suggest that an increase in less mature collagen content in AAA patients does not effectively compensate for the loss of elastin in the aortic wall, and results in a reduced capability to endure wall stresses.

  14. Genotype, development and tissue-derived variation of cell-wall properties in the lignocellulosic energy crop Miscanthus

    SciTech Connect

    da Costa, Ricardo M. F.; Lee, Scott J.; Allison, Gordon G.; Hazen, Samuel P.; Winters, Ana; Bosch, Maurice

    2014-04-15

    Species and hybrids of the genus Miscanthus contain attributes that make them front-runners among current selections of dedicated bioenergy crops. A key trait for plant biomass conversion to biofuels and biomaterials is cell-wall quality; however, knowledge of cell-wall composition and biology in Miscanthus species is limited. This study presents data on cell-wall compositional changes as a function of development and tissue type across selected genotypes, and considers implications for the development of miscanthus as a sustainable and renewable bioenergy feedstock. Cell-wall biomass was analysed for 25 genotypes, considering different developmental stages and stem vs. leaf compositional variability, by Fourier transform mid-infrared spectroscopy and lignin determination. In addition, a Clostridium phytofermentans bioassay was used to assess cell-wall digestibility and conversion to ethanol. Important cell-wall compositional differences between miscanthus stem and leaf samples were found to be predominantly associated with structural carbohydrates. Lignin content increased as plants matured and was higher in stem tissues. Although stem lignin concentration correlated inversely with ethanol production, no such correlation was observed for leaves. Leaf tissue contributed significantly to total above-ground biomass at all stages, although the extent of this contribution was genotype-dependent. In conclusion, it is hypothesized that divergent carbohydrate compositions and modifications in stem and leaf tissues are major determinants for observed differences in cell-wall quality. The findings indicate that improvement of lignocellulosic feedstocks should encompass tissue-dependent variation as it affects amenability to biological conversion. For gene-trait associations relating to cell-wall quality, the data support the separate examination of leaf and stem composition, as tissue-specific traits may be masked by considering only total above-ground biomass

  15. Resistance to antiangiogenic therapy is directed by vascular phenotype, vessel stabilization, and maturation in malignant melanoma

    PubMed Central

    Scheffrahn, Inka; Bartling, Sönke; Weis, Joachim; von Felbert, Verena; Middleton, Mark; Kato, Masahi; Ergün, Süleyman; Augustin, Hellmut G.

    2010-01-01

    Angiogenesis is not only dependent on endothelial cell invasion and proliferation, it also requires pericyte coverage of vascular sprouts for stabilization of vascular walls. Clinical efficacy of angiogenesis inhibitors targeting the vascular endothelial growth factor (VEGF) signaling pathway is still limited to date. We hypothesized that the level of vessel maturation is critically involved in the response to antiangiogenic therapies. To test this hypothesis, we evaluated the vascular network in spontaneously developing melanomas of MT/ret transgenic mice after using PTK787/ZK222584 for anti-VEGF therapy but also analyzed human melanoma metastases taken at clinical relapse in patients undergoing adjuvant treatment using bevacizumab. Both experimental settings showed that tumor vessels, which are resistant to anti-VEGF therapy, are characterized by enhanced vessel diameter and normalization of the vascular bed by coverage of mature pericytes and immunoreactivity for desmin, NG-2, platelet-derived growth factor receptor β, and the late-stage maturity marker α smooth muscle actin. Our findings emphasize that the level of mural cell differentiation and stabilization of the vascular wall significantly contribute to the response toward antiangiogenic therapy in melanoma. This study may be useful in paving the way toward a more rational development of second generation antiangiogenic combination therapies and in providing, for the first time, a murine model to study this. PMID:20194633

  16. Pressure and wall shear stress in blood hammer - Analytical theory.

    PubMed

    Mei, Chiang C; Jing, Haixiao

    2016-10-01

    We describe an analytical theory of blood hammer in a long and stiffened artery due to sudden blockage. Based on the model of a viscous fluid in laminar flow, we derive explicit expressions of oscillatory pressure and wall shear stress. To examine the effects on local plaque formation we also allow the blood vessel radius to be slightly nonuniform. Without resorting to discrete computation, the asymptotic method of multiple scales is utilized to deal with the sharp contrast of time scales. The effects of plaque and blocking time on blood pressure and wall shear stress are studied. The theory is validated by comparison with existing water hammer experiments. Copyright © 2016. Published by Elsevier Inc.

  17. Bioengineered blood vessels.

    PubMed

    Niu, Guoguang; Sapoznik, Etai; Soker, Shay

    2014-04-01

    Cardiovascular disease (CVD) affecting blood vessel function is a leading cause of death around the world. A common treatment option to replace the diseased blood vessels is vascular grafting using the patient's own blood vessels. However, patients with CVD are usually lacking vessels for grafting. Recent advances in tissue engineering are now providing alternatives to autologous vascular grafts in the form of tissue-engineered blood vessels (TEBVs). In this review, we will describe the use of different scaffolding systems, cell sources and conditioning approaches for creating fully functional blood vessels. Additionally, we will present the methods used for assessing TEBV functions and describe preclinical and clinical trials for TEBV. Although the early results were encouraging, current designs of TEBV still fall short as a viable clinical option. Implementing the current knowledge in vascular development can lead to improved fabrication and function of TEBV and hasten clinical translation.

  18. Pressure vessel bottle mount

    NASA Technical Reports Server (NTRS)

    Wingett, Paul (Inventor)

    2001-01-01

    A mounting assembly for mounting a composite pressure vessel to a vehicle includes a saddle having a curved surface extending between two pillars for receiving the vessel. The saddle also has flanged portions which can be bolted to the vehicle. Each of the pillars has hole in which is mounted the shaft portion of an attachment member. A resilient member is disposed between each of the shaft portions and the holes and loaded by a tightening nut. External to the holes, each of the attachment members has a head portion to which a steel band is attached. The steel band circumscribes the vessel and translates the load on the springs into a clamping force on the vessel. As the vessel expands and contracts, the resilient members expand and contract so that the clamping force applied by the band to the vessel remains constant.

  19. The diagnostic value of ultrasonography-derived edema of the temporal artery wall in giant cell arteritis: a second meta-analysis

    PubMed Central

    2010-01-01

    Background Ultrasonography of temporal arteries is not commonly used in the approach of patients with suspected giant cell arteritis (GCA) in clinical practice. A meta-analysis of primary studies available through April 2004 concluded that ultrasonography could indeed be helpful in diagnosing GCA. We specifically re-examined the diagnostic value of the ultrasonography-derived halo sign, a dark hypoechoic circumferential thickening around the artery lumen, indicating vasculitic wall edema, in GCA. Methods Original, prospective studies in patients with suspected GCA that examined ultrasonography findings of temporal arteries using the ACR 1990 classification criteria for GCA as reference standard, published through 2009, were identified. Only eight studies involving 575 patients, 204 of whom received the final diagnosis of GCA, fulfilled technical quality criteria for ultrasound. Weighted sensitivity and specificity estimates of the halo sign were assessed, their possible heterogeneity was investigated and pooled diagnostic odds ratio was determined. Results Unilateral halo sign achieved an overall sensitivity of 68% (95% CI, 0.61-0.74) and specificity of 91% (95% CI, 0.88-0.94) for GCA. The values of inconsistency coefficient (I2) of both sensitivity and specificity of the halo sign, showed significant heterogeneity concerning the results between studies. Pooled diagnostic odds ratio, expressing how much greater the odds of having GCA are for patients with halo sign than for those without, was 34 (95% CI, 8.21-138.23). Diagnostic odds ratio was further increased to 65 (95% CI, 17.86-236.82) when bilateral halo signs were present (sensitivity/specificity of 43% and 100%, respectively). In both cases, it was found that DOR was constant across studies. Conclusion Temporal artery edema demonstrated as halo sign should be always looked for in ultrasonography when GCA is suspected. Providing that currently accepted technical quality criteria are fulfilled, halo sign

  20. Vessel visualization using curved surface reformation.

    PubMed

    Auzinger, Thomas; Mistelbauer, Gabriel; Baclija, Ivan; Schernthaner, Rüdiger; Köchl, Arnold; Wimmer, Michael; Gröller, M Eduard; Bruckner, Stefan

    2013-12-01

    Visualizations of vascular structures are frequently used in radiological investigations to detect and analyze vascular diseases. Obstructions of the blood flow through a vessel are one of the main interests of physicians, and several methods have been proposed to aid the visual assessment of calcifications on vessel walls. Curved Planar Reformation (CPR) is a wide-spread method that is designed for peripheral arteries which exhibit one dominant direction. To analyze the lumen of arbitrarily oriented vessels, Centerline Reformation (CR) has been proposed. Both methods project the vascular structures into 2D image space in order to reconstruct the vessel lumen. In this paper, we propose Curved Surface Reformation (CSR), a technique that computes the vessel lumen fully in 3D. This offers high-quality interactive visualizations of vessel lumina and does not suffer from problems of earlier methods such as ambiguous visibility cues or premature discretization of centerline data. Our method maintains exact visibility information until the final query of the 3D lumina data. We also present feedback from several domain experts.

  1. Behavior of platelets stained by 5,6-CF-encapsulated PEGylated liposomes after laser irradiation of vessel wall: an in-vivo model for studying site-selective delivery of diagnostic or therapeutic agents

    NASA Astrophysics Data System (ADS)

    Mordon, Serge R.; Begu, Sylvie; Buys, Bruno; Tourne-Peteilh, Corine; Devoisselle, Jean-Marie

    2001-05-01

    Vascular endothelium serves as an extensive interface between circulating blood and various tissues and organs of the body. As such, it offers an accessible target for blood-borne pharmacological and genetic manipulations that can mediate both local and systemic effects. Thus, targeting of liposomes to activated vascular endothelial cells may provide a strategy for site-selective delivery in the vascular system with broad therapeutic applicability. This study aimed to evaluate an intravital fluorescence imaging technique to visualize in-situ and in real-time the activation of platelets after staining by 5,6-CF- encapsulated PEGylated liposomes injected intravenously. The study was performed on skin by using a dorsal skin-fold chamber implanted in golden hamsters using intravital microscopy. The skin micro circulation was observed with an intravital microscope (using x25 and x40 magnification) fitted with a Xenon light source and an epi-fluorescence assembly. An ultra-high sensitivity video-camera mounted on the microscope projected the image onto a monitor, and the images were recorded for play-back analysis with a digital video cassette recorder. An inflammatory response was induced by an Argon laser emitting at 514.5nm. The 80micrometers laser beam was focused on a vessel and its position was controlled with the microscope imaging system, it was possible to see individual platelets flowing in blood vessels. As liposomes were labeled with a fluorescent probe which was hydrophilic (located in the aqueous phase), the fluorescence of platelets was due only to the uptake of liposomes. After laser irradiation, platelets activation at sites of vascular injury was obtained. Tethering, translocation of some platelets inside the irradiated zone were clearly seen. At last, detachment and extravasation of platelets were observed. A perivascular fluorescence confirmed that platelets migrated across the basal lamina into the dermal connective tissue. In conclusion, staining of

  2. Tumor Blood Vessel Dynamics

    NASA Astrophysics Data System (ADS)

    Munn, Lance

    2009-11-01

    ``Normalization'' of tumor blood vessels has shown promise to improve the efficacy of chemotherapeutics. In theory, anti-angiogenic drugs targeting endothelial VEGF signaling can improve vessel network structure and function, enhancing the transport of subsequent cytotoxic drugs to cancer cells. In practice, the effects are unpredictable, with varying levels of success. The predominant effects of anti-VEGF therapies are decreased vessel leakiness (hydraulic conductivity), decreased vessel diameters and pruning of the immature vessel network. It is thought that each of these can influence perfusion of the vessel network, inducing flow in regions that were previously sluggish or stagnant. Unfortunately, when anti-VEGF therapies affect vessel structure and function, the changes are dynamic and overlapping in time, and it has been difficult to identify a consistent and predictable normalization ``window'' during which perfusion and subsequent drug delivery is optimal. This is largely due to the non-linearity in the system, and the inability to distinguish the effects of decreased vessel leakiness from those due to network structural changes in clinical trials or animal studies. We have developed a mathematical model to calculate blood flow in complex tumor networks imaged by two-photon microscopy. The model incorporates the necessary and sufficient components for addressing the problem of normalization of tumor vasculature: i) lattice-Boltzmann calculations of the full flow field within the vasculature and within the tissue, ii) diffusion and convection of soluble species such as oxygen or drugs within vessels and the tissue domain, iii) distinct and spatially-resolved vessel hydraulic conductivities and permeabilities for each species, iv) erythrocyte particles advecting in the flow and delivering oxygen with real oxygen release kinetics, v) shear stress-mediated vascular remodeling. This model, guided by multi-parameter intravital imaging of tumor vessel structure

  3. Confinement Vessel Assay System: Calibration and Certification Report

    SciTech Connect

    Frame, Katherine C.; Bourne, Mark M.; Crooks, William J.; Evans, Louise; Gomez, Cipriano; Mayo, Douglas R.; Miko, David K.; Salazar, William R.; Stange, Sy; Vigil, Georgiana M.

    2012-07-17

    Los Alamos National Laboratory has a number of spherical confinement vessels (CVs) remaining from tests involving nuclear materials. These vessels have an inner diameter of 6 feet with 1 to 2 inch thick steel walls. The goal of the Confinement Vessel Disposition (CVD) project is to remove debris and reduce contamination inside the vessels. The Confinement Vessel Assay System (CVAS) was developed to measure the amount of SNM in CVs before and after cleanout. Prior to cleanout, the system will be used to perform a verification measurement of each vessel. After cleanout, the system will be used to perform safeguards-quality assays of {le} 100-g {sup 239}Pu equivalent in a vessel for safeguards termination. The system was calibrated in three different mass regions (low, medium, and high) to cover the entire plutonium mass range that will be assayed. The low mass calibration and medium mass calibration were verified for material positioned in the center of an empty vessel. The systematic uncertainty due to position bias was estimated using an MCNPX model to simulate the response of the system to material localized at various points along the inner surface of the vessel. The background component due to cosmic ray spallation was determined by performing measurements of an empty vessel and comparing to measurements in the same location with no vessel present. The CVAS has been tested and calibrated in preparation for verification and safeguards measurements of CVs before and after cleanout.

  4. Heating of blood vessels exposed to laser light

    NASA Astrophysics Data System (ADS)

    Astafyeva, Liudmila G.; Zheltov, Georgy; Schmidt, Wolf-Dieter

    2003-10-01

    An advanced model of blood vessel heating by laser radiation is proposed for tasks of laser skin surgery and therapy. Blood vessel is modeled by infinite circular cylinder situated in skin dermis. Heat conduction equation taking into account the inhomogeneous internal source function is calculated. The source function inside the blood vessel is calculated according to the theory of diffraction of electromagnetic radiation on infinite circular cylinder. Dynamics of the temperature fields inside the vessels as a function of vessel diameters and duration of irradiance is calculated for the wavelength of 0.532 μm. It is determined the irradiance conditions whereby the near-homogeneous heating along the perimeter of walls of blood vessels on minimum laser exposure to surrounding tissues is achieved.

  5. Acoustic emission testing of 12-nickel maraging steel pressure vessels

    NASA Technical Reports Server (NTRS)

    Dunegan, H. L.

    1973-01-01

    Acoustic emission data were obtained from three point bend fracture toughness specimens of 12-nickel maraging steel, and two pressure vessels of the same material. One of the pressure vessels contained a prefabricated flaw which was extended and sharpened by fatigue cycling. It is shown that the flawed vessel had similar characteristics to the fracture specimens, thereby allowing estimates to be made of its nearness to failure during a proof test. Both the flawed and unflawed pressure vessel survived the proof pressure and 5 cycles to the working pressure, but it was apparent from the acoustic emission response during the proof cycle and the 5 cycles to the working pressure that the flawed vessel was very near failure. The flawed vessel did not survive a second cycle to the proof pressure before failure due to flaw extension through the wall (causing a leak).

  6. Flow in elliptical vessels calculated for a physiological waveform.

    PubMed

    Robertson, M B; Köhler, U; Hoskins, P R; Marshall, I

    2001-01-01

    Understanding the nature of pulsatile flow is an important issue in haemodynamics, especially the initiation and progression of vascular disease. The geometry of a non-circular vessel was idealised to an elliptical cross-section, and the dynamic properties of the flow were calculated for a physiological waveform. The Fourier harmonics for a common carotid waveform were determined, and the velocity profile and wall shear stress were calculated from the superposition of the individual contributions from each harmonic. The effects of ellipticity on the flow pattern were found to be significant. The velocity profile along the major axis of the elliptical cross-section developed a flattened peak, which widened as the vessel became more elliptical. Wall shear stress demonstrated an angular dependence in elliptical vessels, where the point of minimum shear stress was located at the end of the major axis. Comparison with a cylindrical vessel demonstrated a 3% decrease in peak wall shear stress (tau = 2.96, N.m(-2)) at the end of the major axis, and 10% in the mean wall shear stress (tau = 0.44 N. m(-2)), for an elliptical vessel (epsilon = 0.8). The temporal average wall shear stress, which has been associated with atherogenic sites, also displayed a minimum at the end of the major axis that decreased with more elliptical cross-sections. Copyright 2001 S. Karger AG, Basel

  7. The LKLF transcription factor is required for normal tunica media formation and blood vessel stabilization during murine embryogenesis

    PubMed Central

    Kuo, Chay T.; Veselits, Margaret L.; Barton, Kevin P.; Lu, Min Min; Clendenin, Cynthia; Leiden, Jeffrey M.

    1997-01-01

    The transcriptional programs that regulate blood vessel formation are largely unknown. In this paper, we examine the role of the zinc finger transcription factor LKLF in murine blood vessel morphogenesis and homeostasis. By in situ hybridization and immunohistochemistry, we show that LKLF is expressed as early as embryonic day 9.5 (E9.5) in vascular endothelial cells throughout the developing mouse embryo. To better understand the function of LKLF, we used homologous recombination in embryonic stem (ES) cells to generate LKLF-deficient (LKLF−/−) mice. Both angiogenesis and vasculogenesis were normal in the LKLF−/− mice. However, LKLF−/− embryos died between E12.5 and E14.5 from severe intra-embryonic and intra-amniotic hemorrhaging. This bleeding disorder was associated with specific defects in blood vessel morphology. Umbilical veins and arteries in the LKLF−/− embryos displayed an abnormally thin tunica media and aneurysmal dilatation before rupturing into the amniotic cavity. Similarly, vascular smooth muscle cells in the aortae from the LKLF−/− animals displayed a cuboidal morphology and failed to organize into a compact tunica media. Consistent with these findings, electron microscopic analyses demonstrated endothelial cell necrosis, significant reductions in the number of vessel-wall pericytes and differentiating smooth muscle cells, and decreased deposition of extracellular matrix in the LKLF−/− vessels. Despite these defects, in situ hybridization demonstrated normal expression of platelet-derived growth factor B, Tie1, Tie2, transforming growth factor β, and heparin-binding epidermal growth factor in the vasculature of the LKLF−/− embryos. Therefore, LKLF defines a novel transcriptional pathway in which endothelial cells regulate the assembly of the vascular tunica media and concomitant vessel wall stabilization during mammalian embryogenesis. PMID:9367982

  8. Method of fabricating a prestressed cast iron vessel

    DOEpatents

    Lampe, Robert F.

    1982-01-01

    A method of fabricating a prestressed cast iron vessel wherein double wall cast iron body segments each have an arcuate inner wall and a spaced apart substantially parallel outer wall with a plurality of radially extending webs interconnecting the inner wall and the outer wall, the bottom surface and the two exposed radial side surfaces of each body segment are machined and eight body segments are formed into a ring. The top surfaces and outer surfaces of the outer walls are machined and keyways are provided across the juncture of adjacent end walls of the body segments. A liner segment complementary in shape to a selected inner wall of one of the body segments is mounted to each of the body segments and again formed into a ring. The liner segments of each ring are welded to form unitary liner rings and thereafter the cast iron body segments are prestressed to complete the ring assembly. Ring assemblies are stacked to form the vessel and adjacent unitary liner rings are welded. A top head covers the top ring assembly to close the vessel and axially extending tendons retain the top and bottom heads in place under pressure.

  9. Patient-specific models of wall stress in abdominal aortic aneurysm: a comparison between MR and CT

    NASA Astrophysics Data System (ADS)

    de Putter, Sander; Breeuwer, Marcel; van de Vosse, Frans N.; Kose, Ursula; Gerritsen, Frans A.

    2006-03-01

    Finite element method based patient-specific wall stress in abdominal aortic aneurysm (AAA) may provide a more accurate rupture risk predictor than the currently used maximum transverse diameter. In this study, we have investigated the sensitivity of the wall stress in AAA with respect to geometrical variations. We have acquired MR and CT images for four patients with AAA. Three individual users have delineated the AAA vessel wall contours on the image slices. These contours were used to generate synthetic feature images for a deformable model based segmentation method. We investigated the reproducibility and the influence of the user variability on the wall stress. For sufficiently smooth models of the AAA wall, the peak wall stress is reproducible for three out of the four AAA geometries. The 0.99 percentiles of the wall stress show excellent reproducibility for all four AAAs. The variations induced by user variability are larger than the errors caused by the segmentation variability. The influence of the user variability appears to be similar for MR and CT. We conclude that the peak wall stress in AAA is sensitive to small geometrical variations. To increase reproducibility it appears to be best not to allow too much geometrical detail in the simulations. This could be achieved either by using a sufficiently smooth geometry representation or by using a more robust statistical parameter derived from the wall stress distribution.

  10. REUSABLE REACTION VESSEL

    DOEpatents

    Soine, T.S.

    1963-02-26

    This patent shows a reusable reaction vessel for such high temperature reactions as the reduction of actinide metal chlorides by calcium metal. The vessel consists of an outer metal shell, an inner container of refractory material such as sintered magnesia, and between these, a bed of loose refractory material impregnated with thermally conductive inorganic salts. (AEC)

  11. Imprinted Clay Coil Vessels

    ERIC Educational Resources Information Center

    Lohr, Tresa Rae

    2006-01-01

    The author teaches clay vessel construction in the fifth grade, and it is amazing what can be accomplished in one forty-five minute period when the expectations are clarified in the initial lesson. The author introduces clay coil vessels with a discussion of the sources of clay and how clay relates to fifth-grade science curriculum concepts such…

  12. Imprinted Clay Coil Vessels

    ERIC Educational Resources Information Center

    Lohr, Tresa Rae

    2006-01-01

    The author teaches clay vessel construction in the fifth grade, and it is amazing what can be accomplished in one forty-five minute period when the expectations are clarified in the initial lesson. The author introduces clay coil vessels with a discussion of the sources of clay and how clay relates to fifth-grade science curriculum concepts such…

  13. Device for inspecting vessel surfaces

    DOEpatents

    Appel, D. Keith

    1995-01-01

    A portable, remotely-controlled inspection crawler for use along the walls of tanks, vessels, piping and the like. The crawler can be configured to use a vacuum chamber for supporting itself on the inspected surface by suction or a plurality of magnetic wheels for moving the crawler along the inspected surface. The crawler is adapted to be equipped with an ultrasonic probe for mapping the structural integrity or other characteristics of the surface being inspected. Navigation of the crawler is achieved by triangulation techniques between a signal transmitter on the crawler and a pair of microphones attached to a fixed, remote location, such as the crawler's deployment unit. The necessary communications are established between the crawler and computers external to the inspection environment for position control and storage and/or monitoring of data acquisition.

  14. Buffered explosions in steel pressure vessels

    SciTech Connect

    Glenn, L.A.

    1986-01-01

    The impulse delivered to the walls of a vessel containing an explosion will increase if material is placed between the walls and the charge. If the impulse application time is small in compared with the eigenperiod of the vessel, the wall stress will increase in direct proportion to the impulse. Conversely, if the application period can be extended beyond half the eigenperiod, the peak stress will be proportional to the ratio of the impulse to the delivery period. With powder or granular buffers, it is possible for the delivery period to increase faster than the impulse as the buffer mass is increased. This is the reason why certain powders, or porous materials, can provide stress reduction even below that observed by evacuating the space between the walls and the explosive. If the buffer material is to serve as an effective mitigator, it must collapse on shock loading to a final density that depends only weakly on pressure; the criterion is that the wave speed in the material that impacts the wall must be small comparison with the impact (particle) speed. This behavior apparently occurs with salt, at least for modest values of the charge parameter, but to a lesser extent with snow under the same conditions. The vermiculite data are comparable to the salt in the charge paramete region where the two overlap; with increasing explosive, however, the vermiculite appears to behave like the snow and its effectiveness as a mitigator rapidly diminishes. It is also clear that once the wave speed criterion is seriously violated, the use of a powder buffer will result in a higher wall stress than if only air filled the space between walls and charge. 5 refs.

  15. Vascular active contour for vessel tree segmentation.

    PubMed

    Shang, Yanfeng; Deklerck, Rudi; Nyssen, Edgard; Markova, Aneta; de Mey, Johan; Yang, Xin; Sun, Kun

    2011-04-01

    In this paper, a novel active contour model is proposed for vessel tree segmentation. First, we introduce a region competition-based active contour model exploiting the gaussian mixture model, which mainly segments thick vessels. Second, we define a vascular vector field to evolve the active contour along its center line into the thin and weak vessels. The vector field is derived from the eigenanalysis of the Hessian matrix of the image intensity in a multiscale framework. Finally, a dual curvature strategy, which uses a vesselness measure-dependent function selecting between a minimal principal curvature and a mean curvature criterion, is added to smoothen the surface of the vessel without changing its shape. The developed model is used to extract the liver and lung vessel tree as well as the coronary artery from high-resolution volumetric computed tomography images. Comparisons are made with several classical active contour models and manual extraction. The experiments show that our model is more accurate and robust than these classical models and is, therefore, more suited for automatic vessel tree extraction.

  16. Quantification of disturbed wall shear stress patterns in complex cardiovascular flows

    NASA Astrophysics Data System (ADS)

    Arzani, Amirhossein; Shadden, Shawn C.

    2014-11-01

    Wall shear stress (WSS) affects the cardiovascular system in numerous ways, and is thought to play an important role in the pathology of many cardiovascular diseases. The (endothelial) cells lining the inner wall of blood vessels, and perhaps the cells inside the vessel wall, can actively sense WSS and respond both chemically and mechanically. The complexity of WSS in cardiovascular flows extends both spatially and temporally. Furthermore, WSS has magnitude and direction. These facets make simple quantification of WSS in cardiovascular applications difficult. In this study we propose a framework to quantify measures such as WSS angle gradient, WSS magnitude gradient, WSS angle time derivative and WSS magnitude time derivative. We will explain the relation of these parameters to the tensorial WSS gradient and WSS vector time derivative, and propose a new methodology to unify these concepts into a single measure. The correlation between these metrics and more common WSS metrics used in the literature will be demonstrated. For demonstration, these methods will be used for the quantification of complex blood flow inside abdominal aortic aneurysms.

  17. TPX vacuum vessel transient thermal and stress conditions

    SciTech Connect

    Feldshteyn, Y.; Dinkevich, S.; Feng, T.; Majumder, D.

    1995-12-31

    The TPX vacuum vessel provides the vacuum boundary for the plasma and the mechanical support for the internal components. Another function of the vacuum vessel is to contain neutron shielding water in the double wall space during normal operation. This double wall space serves as a heat reservoir for the entire vacuum vessel during bakeout. The vacuum vessel and the internal components are subjected to thermal stresses induced by a nonuniform temperature distribution within the structure during bakeout. A successful Conceptual Design Review in March 1993 has established superheated steam as the heating source of the vacuum vessel. A transient bakeout mode of the vacuum vessel and in-vessel components has been analyzed to evaluate transient period duration, proper temperature level, actual thermal stresses and performance of the steam equipment. Thermally, the vacuum vessel structure may be considered as an adiabatic system because it is perfectly insulated by the strong surrounding vacuum and multiple layers of superinsulation. Important aspects of the analysis are described herein.

  18. Injection of vessel-derived stem cells prevents dilated cardiomyopathy and promotes angiogenesis and endogenous cardiac stem cell proliferation in mdx/utrn-/- but not aged mdx mouse models for duchenne muscular dystrophy.

    PubMed

    Chun, Ju Lan; O'Brien, Robert; Song, Min Ho; Wondrasch, Blake F; Berry, Suzanne E

    2013-01-01

    Duchenne muscular dystrophy (DMD) is the most common form of muscular dystrophy. DMD patients lack dystrophin protein and develop skeletal muscle pathology and dilated cardiomyopathy (DCM). Approximately 20% succumb to cardiac involvement. We hypothesized that mesoangioblast stem cells (aorta-derived mesoangioblasts [ADMs]) would restore dystrophin and alleviate or prevent DCM in animal models of DMD. ADMs can be induced to express cardiac markers, including Nkx2.5, cardiac tropomyosin, cardiac troponin I, and α-actinin, and adopt cardiomyocyte morphology. Transplantation of ADMs into the heart of mdx/utrn(-/-) mice prior to development of DCM prevented onset of cardiomyopathy, as measured by echocardiography, and resulted in significantly higher CD31 expression, consistent with new vessel formation. Dystrophin-positive cardiomyocytes and increased proliferation of endogenous Nestin(+) cardiac stem cells were detected in ADM-injected heart. Nestin(+) striated cells were also detected in four of five mdx/utrn(-/-) hearts injected with ADMs. In contrast, when ADMs were injected into the heart of aged mdx mice with advanced fibrosis, no functional improvement was detected by echocardiography. Instead, ADMs exacerbated some features of DCM. No dystrophin protein, increase in CD31 expression, or increase in Nestin(+) cell proliferation was detected following ADM injection in aged mdx heart. Dystrophin was observed following transplantation of ADMs into the hearts of young mdx mice, however, suggesting that pathology in aged mdx heart may alter the fate of donor stem cells. In summary, ADMs delay or prevent development of DCM in dystrophin-deficient heart, but timing of stem cell transplantation may be critical for achieving benefit with cell therapy in DMD cardiac muscle.

  19. Injection of Vessel-Derived Stem Cells Prevents Dilated Cardiomyopathy and Promotes Angiogenesis and Endogenous Cardiac Stem Cell Proliferation in mdx/utrn−/− but Not Aged mdx Mouse Models for Duchenne Muscular Dystrophy

    PubMed Central

    Chun, Ju Lan; O'Brien, Robert; Song, Min Ho; Wondrasch, Blake F.

    2013-01-01

    Duchenne muscular dystrophy (DMD) is the most common form of muscular dystrophy. DMD patients lack dystrophin protein and develop skeletal muscle pathology and dilated cardiomyopathy (DCM). Approximately 20% succumb to cardiac involvement. We hypothesized that mesoangioblast stem cells (aorta-derived mesoangioblasts [ADMs]) would restore dystrophin and alleviate or prevent DCM in animal models of DMD. ADMs can be induced to express cardiac markers, including Nkx2.5, cardiac tropomyosin, cardiac troponin I, and α-actinin, and adopt cardiomyocyte morphology. Transplantation of ADMs into the heart of mdx/utrn−/− mice prior to development of DCM prevented onset of cardiomyopathy, as measured by echocardiography, and resulted in significantly higher CD31 expression, consistent with new vessel formation. Dystrophin-positive cardiomyocytes and increased proliferation of endogenous Nestin+ cardiac stem cells were detected in ADM-injected heart. Nestin+ striated cells were also detected in four of five mdx/utrn−/− hearts injected with ADMs. In contrast, when ADMs were injected into the heart of aged mdx mice with advanced fibrosis, no functional improvement was detected by echocardiography. Instead, ADMs exacerbated some features of DCM. No dystrophin protein, increase in CD31 expression, or increase in Nestin+ cell proliferation was detected following ADM injection in aged mdx heart. Dystrophin was observed following transplantation of ADMs into the hearts of young mdx mice, however, suggesting that pathology in aged mdx heart may alter the fate of donor stem cells. In summary, ADMs delay or prevent development of DCM in dystrophin-deficient heart, but timing of stem cell transplantation may be critical for achieving benefit with cell therapy in DMD cardiac muscle. PMID:23283493

  20. An endothelium-derived hyperpolarizing factor distinct from NO and prostacyclin is a major endothelium-dependent vasodilator in resistance vessels of wild-type and endothelial NO synthase knockout mice

    PubMed Central

    Brandes, Ralf P.; Schmitz-Winnenthal, Friedrich-Hubertus; Félétou, Michel; Gödecke, Axel; Huang, Paul L.; Vanhoutte, Paul M.; Fleming, Ingrid; Busse, Rudi

    2000-01-01

    In addition to nitric oxide (NO) and prostacyclin (PGI2), the endothelium generates the endothelium-derived hyperpolarizing factor (EDHF). We set out to determine whether an EDHF-like response can be detected in wild-type (WT) and endothelial NO synthase knockout mice (eNOS −/−) mice. Vasodilator responses to endothelium-dependent agonists were determined in vivo and in vitro. In vivo, bradykinin induced a pronounced, dose-dependent decrease in mean arterial pressure (MAP) which did not differ between WT and eNOS −/− mice and was unaffected by treatment with Nω-nitro-l-arginine methyl ester and diclofenac. In the saline-perfused hindlimb of WT and eNOS −/− mice, marked Nω-nitro-l-arginine (l-NA, 300 μmol/liter)- and diclofenac-insensitive vasodilations in response to both bradykinin and acetylcholine (ACh) were observed, which were more pronounced than the agonist-induced vasodilation in the hindlimb of WT in the absence of l-NA. This endothelium-dependent, NO/PGI2-independent vasodilatation was sensitive to KCl (40 mM) and to the combination of apamin and charybdotoxin. Gap junction inhibitors (18α-glycyrrhetinic acid, octanol, heptanol) and CB-1 cannabinoid-receptor agonists (Δ9-tetrahydrocannabinol, HU210) impaired EDHF-mediated vasodilation, whereas inhibition of cytochrome P450 enzymes, soluble guanylyl cyclase, or adenosine receptors had no effect on EDHF-mediated responses. These results demonstrate that in murine resistance vessels the predominant agonist-induced endothelium-dependent vasodilation in vivo and in vitro is not mediated by NO, PGI2, or a cytochrome P450 metabolite, but by an EDHF-like principle that requires functional gap junctions. PMID:10944233

  1. Wonderful Walls

    ERIC Educational Resources Information Center

    Greenman, Jim

    2006-01-01

    In this article, the author emphasizes the importance of "working" walls in children's programs. Children's programs need "working" walls (and ceilings and floors) which can be put to use for communication, display, storage, and activity space. The furnishings also work, or don't work, for the program in another sense: in aggregate, they serve as…

  2. Asymptotic dynamics of monopole walls

    NASA Astrophysics Data System (ADS)

    Cross, R.

    2015-08-01

    We determine the asymptotic dynamics of the U(N) doubly periodic BPS monopole in Yang-Mills-Higgs theory, called a monopole wall, by exploring its Higgs curve using the Newton polytope and amoeba. In particular, we show that the monopole wall splits into subwalls when any of its moduli become large. The long-distance gauge and Higgs field interactions of these subwalls are Abelian, allowing us to derive an asymptotic metric for the monopole wall moduli space.

  3. Absorbed dose calculations to blood and blood vessels for internally deposited radionuclides

    SciTech Connect

    Akabani, G.; Poston, J.W. Sr. )

    1991-05-01

    At present, absorbed dose calculations for radionuclides in the human circulatory system used relatively simple models and are restricted in their applications. To determine absorbed doses to the blood and to the surface of the blood vessel wall, EGS4 Monte Carlo calculations were performed. Absorbed doses were calculated for the blood and the blood vessel wall (lumen) for different blood vessels sizes. The radionuclides chosen for this study were those commonly used in nuclear medicine. No penetration of the radionuclide into the blood vessel was assumed nor was cross fire between the vessel assumed. The results are useful in assessing the dose to blood and blood vessel walls for different nuclear medicine procedures.

  4. Absorbed dose calculations to blood and blood vessels for internally deposited radionuclides

    SciTech Connect

    Akabani, G. ); Poston, J.W. . Dept. of Nuclear Engineering)

    1991-05-01

    At present, absorbed dose calculations for radionuclides in the human circulatory system used relatively simple models and are restricted in their applications. To determine absorbed doses to the blood and to the surface of the blood vessel wall, EGS4 Monte Carlo calculations were performed. Absorbed doses were calculated for the blood and the blood vessel wall (lumen) for different blood vessels sizes. The radionuclides chosen for this study were those commonly used in nuclear medicine. No diffusion of the radionuclide into the blood vessel was assumed nor cross fire between vessel was assumed. Results are useful in assessing the dose in blood and blood vessel walls for different nuclear medicine procedures. 6 refs., 6 figs., 5 tabs.

  5. Advanced composite fiber/metal pressure vessels for aircraft applications

    NASA Astrophysics Data System (ADS)

    Papanicolopoulos, Aleck

    1993-06-01

    Structural Composites Industries has developed, qualified, and delivered a number of high performance carbon epoxy overwrapped/seamless aluminum liner pressure vessels for use in military aircraft where low weight, low cost, high operating pressure and short lead time are the primary considerations. This paper describes product design, development, and qualification for a typical program. The vessel requirements included a munitions insensitivity criterion as evidenced by no fragmentation following impact by a .50 cal tumbling bullet. This was met by the development of a carbon-Spectra hybrid composite overwrap on a thin-walled seamless aluminum liner. The same manufacturing, inspection, and test processes that are used to produce lightweight, thin walled seamless aluminum lined carbon/epoxy overwrapped pressure vessels for satellite and other space applications were used to fabricate this vessel. This report focuses on the results of performance in the qualification testing.

  6. Pressure vessel flex joint

    NASA Technical Reports Server (NTRS)

    Kahn, Jon B. (Inventor)

    1992-01-01

    An airtight, flexible joint is disclosed for the interfacing of two pressure vessels such as between the Space Station docking tunnel and the Space Shuttle Orbiter bulkhead adapter. The joint provides for flexibility while still retaining a structural link between the two vessels required due to the loading created by the internal/external pressure differential. The joint design provides for limiting the axial load carried across the joint to a specific value, a function returned in the Orbiter/Station tunnel interface. The flex joint comprises a floating structural segment which is permanently attached to one of the pressure vessels through the use of an inflatable seal. The geometric configuration of the joint causes the tension between the vessels created by the internal gas pressure to compress the inflatable seal. The inflation pressure of the seal is kept at a value above the internal/external pressure differential of the vessels in order to maintain a controlled distance between the floating segment and pressure vessel. The inflatable seal consists of either a hollow torus-shaped flexible bladder or two rolling convoluted diaphragm seals which may be reinforced by a system of straps or fabric anchored to the hard structures. The joint acts as a flexible link to allow both angular motion and lateral displacement while it still contains the internal pressure and holds the axial tension between the vessels.

  7. Cholinergic innervation of human mesenteric lymphatic vessels.

    PubMed

    D'Andrea, V; Bianchi, E; Taurone, S; Mignini, F; Cavallotti, C; Artico, M

    2013-11-01

    The cholinergic neurotransmission within the human mesenteric lymphatic vessels has been poorly studied. Therefore, our aim is to analyse the cholinergic nerve fibres of lymphatic vessels using the traditional enzymatic techniques of staining, plus the biochemical modifications of acetylcholinesterase (AChE) activity. Specimens obtained from human mesenteric lymphatic vessels were subjected to the following experimental procedures: 1) drawing, cutting and staining of tissues; 2) staining of total nerve fibres; 3) enzymatic staining of cholinergic nerve fibres; 4) homogenisation of tissues; 5) biochemical amount of proteins; 6) biochemical amount of AChE activity; 6) quantitative analysis of images; 7) statistical analysis of data. The mesenteric lymphatic vessels show many AChE positive nerve fibres around their wall with an almost plexiform distribution. The incubation time was performed at 1 h (partial activity) and 6 h (total activity). Moreover, biochemical dosage of the same enzymatic activity confirms the results obtained with morphological methods. The homogenates of the studied tissues contain strong AChE activity. In our study, the lymphatic vessels appeared to contain few cholinergic nerve fibres. Therefore, it is expected that perivascular nerve stimulation stimulates cholinergic nerves innervating the mesenteric arteries to release the neurotransmitter AChE, which activates muscarinic or nicotinic receptors to modulate adrenergic neurotransmission. These results strongly suggest, that perivascular cholinergic nerves have little or no effect on the adrenergic nerve function in mesenteric arteries. The cholinergic nerves innervating mesenteric arteries do not mediate direct vascular responses.

  8. Three-dimensional wet-electrospun poly(lactic acid)/multi-wall carbon nanotubes scaffold induces differentiation of human menstrual blood-derived stem cells into germ-like cells.

    PubMed

    Eyni, Hossein; Ghorbani, Sadegh; Shirazi, Reza; Salari Asl, Leila; P Beiranvand, Shahram; Soleimani, Masoud

    2017-09-01

    Infertility caused by the disruption or absence of germ cells is a major and largely incurable medical problem. Germ cells (i.e., sperm or egg) play a key role in the transmission of genetic and epigenetic information across generations. Generation of gametes derived in vitro from stem cells hold promising prospects which could potentially help infertile men and women. Menstrual blood-derived stem cells are a unique stem cell source. Evidence suggests that menstrual blood-derived stem cells exhibit a multi-lineage potential and have attracted extensive attention in regenerative medicine. To maintain the three-dimensional structure of natural extra cellular matrices in vitro, scaffolds can do this favor and mimic a microenvironment for cell proliferation and differentiation. According to previous studies, poly(lactic acid) and multi-wall carbon nanotubes have been introduced as novel and promising biomaterials for the proliferation and differentiation of stem cells. Some cell types have been successfully grown on a matrix containing carbon nanotubes in tissue engineering but there is no report for this material to support stem cells differentiation into germ cells lineage. This study designed a 3D wet-electrospun poly(lactic acid) and poly(lactic acid)/multi-wall carbon nanotubes composite scaffold to compare infiltration, proliferation, and differentiation potential of menstrual blood-derived stem cells toward germ cell lineage with 2D culture. Our primary data revealed that the fabricated scaffold has mechanical and biological suitable qualities for supporting and attachments of stem cells. The differentiated menstrual blood-derived stem cells tracking in scaffolds using scanning electron microscopy confirmed cell attachment, aggregation, and distribution on the porous scaffold. Based on the differentiation assay by RT-PCR analysis, stem cells and germ-like cells markers were expressed in 3D groups as well as 2D one. It seems that poly(lactic acid)/multi-wall

  9. Reactor vessel support system

    DOEpatents

    Golden, Martin P.; Holley, John C.

    1982-01-01

    A reactor vessel support system includes a support ring at the reactor top supported through a box ring on a ledge of the reactor containment. The box ring includes an annular space in the center of its cross-section to reduce heat flow and is keyed to the support ledge to transmit seismic forces from the reactor vessel to the containment structure. A coolant channel is provided at the outside circumference of the support ring to supply coolant gas through the keyways to channels between the reactor vessel and support ledge into the containment space.

  10. Confinement Vessel Dynamic Analysis

    SciTech Connect

    R. Robert Stevens; Stephen P. Rojas

    1999-08-01

    A series of hydrodynamic and structural analyses of a spherical confinement vessel has been performed. The analyses used a hydrodynamic code to estimate the dynamic blast pressures at the vessel's internal surfaces caused by the detonation of a mass of high explosive, then used those blast pressures as applied loads in an explicit finite element model to simulate the vessel's structural response. Numerous load cases were considered. Particular attention was paid to the bolted port connections and the O-ring pressure seals. The analysis methods and results are discussed, and comparisons to experimental results are made.

  11. Disposal of Vessels at Sea

    EPA Pesticide Factsheets

    Vessel disposal general permits are issued by the EPA under the Marine Protection, Research and Sanctuaries Act. Information is provided for vessel disposal permit applicants and where to dispose a vessel.

  12. Lymphatic vessels in the healthy human dental pulp.

    PubMed

    Marchetti, C; Poggi, P; Calligaro, A; Casasco, A

    1991-01-01

    The lymphatic vessels of the dental pulp have been studied in non-carious teeth of young people. A network of lymphatic vessels drains the pulpal tissue. The lymphatic capillaries are characterized by a thin wall with an irregular profile. Cellular projections rise from the endothelial cells. Micropinocytotic vesicles and intercellular adjoining structures are the main mechanisms for the lymph formation. Multivesicular structures, Weibel-Palade bodies and paracrystalline inclusions have been observed.

  13. Automated measurement of retinal blood vessel tortuosity

    NASA Astrophysics Data System (ADS)

    Joshi, Vinayak; Reinhardt, Joseph M.; Abramoff, Michael D.

    2010-03-01

    Abnormalities in the vascular pattern of the retina are associated with retinal diseases and are also risk factors for systemic diseases, especially cardiovascular diseases. The three-dimensional retinal vascular pattern is mostly formed congenitally, but is then modified over life, in response to aging, vessel wall dystrophies and long term changes in blood flow and pressure. A characteristic of the vascular pattern that is appreciated by clinicians is vascular tortuosity, i.e. how curved or kinked a blood vessel, either vein or artery, appears along its course. We developed a new quantitative metric for vascular tortuosity, based on the vessel's angle of curvature, length of the curved vessel over its chord length (arc to chord ratio), number of curvature sign changes, and combined these into a unidimensional metric, Tortuosity Index (TI). In comparison to other published methods this method can estimate appropriate TI for vessels with constant curvature sign and vessels with equal arc to chord ratios, as well. We applied this method to a dataset of 15 digital fundus images of 8 patients with Facioscapulohumeral muscular dystrophy (FSHD), and to the other publically available dataset of 60 fundus images of normal cases and patients with hypertensive retinopathy, of which the arterial and venous tortuosities have also been graded by masked experts (ophthalmologists). The method produced exactly the same rank-ordered list of vessel tortuosity (TI) values as obtained by averaging the tortuosity grading given by 3 ophthalmologists for FSHD dataset and a list of TI values with high ranking correlation with the ophthalmologist's grading for the other dataset. Our results show that TI has potential to detect and evaluate abnormal retinal vascular structure in early diagnosis and prognosis of retinopathies.

  14. Vessel discoloration detection in malarial retinopathy

    NASA Astrophysics Data System (ADS)

    Agurto, C.; Nemeth, S.; Barriga, S.; Soliz, P.; MacCormick, I.; Taylor, T.; Harding, S.; Lewallen, S.; Joshi, V.

    2016-03-01

    Cerebral malaria (CM) is a life-threatening clinical syndrome associated with malarial infection. It affects approximately 200 million people, mostly sub-Saharan African children under five years of age. Malarial retinopathy (MR) is a condition in which lesions such as whitening and vessel discoloration that are highly specific to CM appear in the retina. Other unrelated diseases can present with symptoms similar to CM, therefore the exact nature of the clinical symptoms must be ascertained in order to avoid misdiagnosis, which can lead to inappropriate treatment and, potentially, death. In this paper we outline the first system to detect the presence of discolored vessels associated with MR as a means to improve the CM diagnosis. We modified and improved our previous vessel segmentation algorithm by incorporating the `a' channel of the CIELab color space and noise reduction. We then divided the segmented vasculature into vessel segments and extracted features at the wall and in the centerline of the segment. Finally, we used a regression classifier to sort the segments into discolored and not-discolored vessel classes. By counting the abnormal vessel segments in each image, we were able to divide the analyzed images into two groups: normal and presence of vessel discoloration due to MR. We achieved an accuracy of 85% with sensitivity of 94% and specificity of 67%. In clinical practice, this algorithm would be combined with other MR retinal pathology detection algorithms. Therefore, a high specificity can be achieved. By choosing a different operating point in the ROC curve, our system achieved sensitivity of 67% with specificity of 100%.

  15. Staphylococcus aureus Penicillin-Binding Protein 2 Can Use Depsi-Lipid II Derived from Vancomycin-Resistant Strains for Cell Wall Synthesis.

    PubMed

    Nakamura, Jun; Yamashiro, Hidenori; Miya, Hiroto; Nishiguchi, Kenzo; Maki, Hideki; Arimoto, Hirokazu

    2013-09-02

    Vancomycin-resistant Staphylococcus aureus (S. aureus) (VRSA) uses depsipeptide-containing modified cell-wall precursors for the biosynthesis of peptidoglycan. Transglycosylase is responsible for the polymerization of the peptidoglycan, and the penicillin-binding protein 2 (PBP2) plays a major role in the polymerization among several transglycosylases of wild-type S. aureus. However, it is unclear whether VRSA processes the depsipeptide-containing peptidoglycan precursor by using PBP2. Here, we describe the total synthesis of depsi-lipid I, a cell-wall precursor of VRSA. By using this chemistry, we prepared a depsi-lipid II analogue as substrate for a cell-free transglycosylation system. The reconstituted system revealed that the PBP2 of S. aureus is able to process a depsi-lipid II intermediate as efficiently as its normal substrate. Moreover, the system was successfully used to demonstrate the difference in the mode of action of the two antibiotics moenomycin and vancomycin.

  16. Staphylococcus aureus Penicillin-Binding Protein 2 Can Use Depsi-Lipid II Derived from Vancomycin-Resistant Strains for Cell Wall Synthesis

    PubMed Central

    Nakamura, Jun; Yamashiro, Hidenori; Miya, Hiroto; Nishiguchi, Kenzo; Maki, Hideki; Arimoto, Hirokazu

    2013-01-01

    Vancomycin-resistant Staphylococcus aureus (S. aureus) (VRSA) uses depsipeptide-containing modified cell-wall precursors for the biosynthesis of peptidoglycan. Transglycosylase is responsible for the polymerization of the peptidoglycan, and the penicillin-binding protein 2 (PBP2) plays a major role in the polymerization among several transglycosylases of wild-type S. aureus. However, it is unclear whether VRSA processes the depsipeptide-containing peptidoglycan precursor by using PBP2. Here, we describe the total synthesis of depsi-lipid I, a cell-wall precursor of VRSA. By using this chemistry, we prepared a depsi-lipid II analogue as substrate for a cell-free transglycosylation system. The reconstituted system revealed that the PBP2 of S. aureus is able to process a depsi-lipid II intermediate as efficiently as its normal substrate. Moreover, the system was successfully used to demonstrate the difference in the mode of action of the two antibiotics moenomycin and vancomycin. PMID:23873669

  17. [Structure of the interalveolar wall].

    PubMed

    Senelar, R

    1975-01-01

    The wall, which unites as well as separates two contiguous pulmonary alveoli is composed of: - a conjuntival partition, the veritable skeleton of the wall, which is occupied, to the largest extent, by capillary blood vessels. Between the capillaries, conjunctival cells are dispursed: fibrocytes, fibroblasts and histiocytes, of which some can be mobilised, transformed into macrophages, and penetrate into the alveolar lumen; - modified epithelial cells, whose very thin, vast expansions cover the conjunctival partition; - a liquid film, 0.2 mu in thickness, which separates the epithelial cells, or pneumocytes from the alveolar air. Numerous physiological implications result from this organisation.

  18. Physiological Degradation of Pectin in Papaya Cell Walls: Release of Long Chains Galacturonans Derived from Insoluble Fractions during Postharvest Fruit Ripening.

    PubMed

    do Prado, Samira B R; Melfi, Paulo R; Castro-Alves, Victor C; Broetto, Sabrina G; Araújo, Elias S; do Nascimento, João R O; Fabi, João P

    2016-01-01

    Papaya (Carica papaya L.) is a fleshy fruit that presents a rapid pulp softening during ripening. However, the timeline on how papaya pectinases act in polysaccharide solubilization and the consequent modification of the cell wall fractions during ripening is still not clear. In this work, the gene expression correlations between, on one hand, 16 enzymes potentially acting during papaya cell wall disassembling and, on the other hand, the monosaccharide composition of cell wall fractions during papaya ripening were evaluated. In order to explain differences in the ripening of papaya samplings, the molecular mass distribution of polysaccharides from water-soluble and oxalate-soluble fractions (WSF and OSF, respectively), as well as the oligosaccharide profiling from the WSF fraction, were evaluated by high performance size exclusion chromatography coupled to a refractive index detector and high performance anion-exchange chromatography coupled to pulse amperometric detection analyses, respectively. Results showed that up-regulated polygalacturonase and β-galactosidase genes were positively correlated with some monosaccharide profiles. In addition, an overall increase in the retention time of high molecular weight (HMW) and low molecular weight (LMW) polysaccharides in WSF and OSF was shown. The apparent disappearance of one HMW peak of the OSF may result from the conversion of pectin that were crosslinked with calcium into more soluble forms through the action of PGs, which would increase the solubilization of polysaccharides by lowering their molecular weight. Thus, the results allowed us to propose a detailed process of papaya cell wall disassembling that would affect sensorial properties and post-harvesting losses of this commercially important fruit.

  19. The influence of artery wall curvature on the anatomical assessment of stenosis severity derived from fractional flow reserve: a computational fluid dynamics study.

    PubMed

    Govindaraju, Kalimuthu; Viswanathan, Girish N; Badruddin, Irfan Anjum; Kamangar, Sarfaraz; Salman Ahmed, N J; Al-Rashed, Abdullah A A A

    2016-11-01

    This study aims to investigate the influence of artery wall curvature on the anatomical assessment of stenosis severity and to identify a region of misinterpretation in the assessment of per cent area stenosis (AS) for functionally significant stenosis using fractional flow reserve (FFR) as standard. Five artery models of different per cent AS severity (70, 75, 80, 85 and 90%) were considered. For each per cent AS severity, the angle of curvature of the arterial wall varied from straight to an increasingly curved model (0°, 30°, 60°, 90° and 120°). Computational fluid dynamics was performed under transient physiologic hyperemic flow conditions to investigate the influence of artery wall curvature on the pressure drop and the FFR. The findings in this study may be useful in in vitro anatomical assessment of functionally significant stenosis. The FFR decreased with increasing stenosis severity for a given curvature of the artery wall. Moreover, a significant decrease in FFR was found between straight and curved models discussed for a given severity condition. These findings indicate that the curvature effect was included in the FFR assessment in contrast to minimum lumen area (MLA) or per cent AS assessment. The MLA or per cent AS assessment may lead to underestimation of stenosis severity. From this numerical study, an uncertainty region could be evaluated using the clinical FFR cutoff value of 0.8. This value was observed at 81.98 and 79.10% AS for arteries with curvature angles of 0° and 120° respectively. In conclusion, the curvature of the artery should not be neglected in in vitro anatomical assessment.

  20. Physiological Degradation of Pectin in Papaya Cell Walls: Release of Long C