WorldWideScience

Sample records for vascular conduit generated

  1. Transformation of nonvascular acellular tissue matrices into durable vascular conduits.

    Science.gov (United States)

    Clarke, D R; Lust, R M; Sun, Y S; Black, K S; Ollerenshaw, J D

    2001-05-01

    Prosthetic grafts commonly used for vascular reconstruction are limited to synthetics and cross-linked tissue grafts. Within these devices, graft infections are common, compliance mismatch is significant, and handling qualities are poor. Natural biological tissues that are unfixed have been shown to resist infections and be durable and compliant. A natural biological matrix that could be remodeled appropriately after implantation would be a desirable graft for vascular reconstruction. SynerGraft tissue engineering strategies have been used to minimize antigenicity and produce stable unfixed vascular grafts from nonvascular bovine tissues. These grafts have replaced the abdominal aortas of 8 dogs that have been followed for up to 10 months. Early evaluation indicates rapid recellularization by recipient smooth muscle actin positive cells, which become arranged circumferentially, into the media. Arterioles were present in the adventitial areas and endothelial cells were seen to cover lumenal surfaces. After 10 months, grafts were patent and not aneurysmal. These data indicate that SynerGraft processing of animal tissues is capable of producing stable vascular conduits that exhibit long-term functionality in other species.

  2. Conduit Vascular Evaluation is Associated with Reduction in Anastomotic Leak After Esophagectomy.

    Science.gov (United States)

    Campbell, Chase; Reames, Mark K; Robinson, Myra; Symanowski, James; Salo, Jonathan C

    2015-05-01

    Anastomotic leak following esophagectomy is associated with significant morbidity and mortality. A major factor determining anastomotic success is an adequate blood supply to the conduit. The aim of this study was to determine the impact of intraoperative evaluation of the conduit's vascular supply on anastomotic failure after esophagectomy. We retrospectively analyzed data from 90 consecutive patients undergoing esophagectomy with gastric conduit reconstruction. A change in surgical practice occurred after 60 cases were completed, when we introduced the use of intraoperative indocyanine green fluorescence angiography and Doppler examination to evaluate blood supply and assist in construction of the conduit. The leak rates before and after implementation of conduit vascular evaluation were compared. After the introduction of intraoperative vascular evaluation of the gastric conduit, we noted a dramatic decrease in the rate of anastomotic leak from 20 % in the first 60 patients to 0 % in the succeeding 30 patients. Intraoperative vascular evaluation with indocyanine green fluorescence imaging and Doppler examination of the gastric conduit used to assist reconstruction after esophagectomy allows for enhanced construction of the conduit that maximizes blood supply to the anastomosis. This change in practice was associated with a significant reduction in anastomotic leak rate.

  3. In vitro evaluation of carbon-nanotube-reinforced bioprintable vascular conduits

    Science.gov (United States)

    Dolati, Farzaneh; Yu, Yin; Zhang, Yahui; De Jesus, Aribet M.; Sander, Edward A.; Ozbolat, Ibrahim T.

    2014-04-01

    Vascularization of thick engineered tissue and organ constructs like the heart, liver, pancreas or kidney remains a major challenge in tissue engineering. Vascularization is needed to supply oxygen and nutrients and remove waste in living tissues and organs through a network that should possess high perfusion ability and significant mechanical strength and elasticity. In this paper, we introduce a fabrication process to print vascular conduits directly, where conduits were reinforced with carbon nanotubes (CNTs) to enhance their mechanical properties and bioprintability. In vitro evaluation of printed conduits encapsulated in human coronary artery smooth muscle cells was performed to characterize the effects of CNT reinforcement on the mechanical, perfusion and biological performance of the conduits. Perfusion and permeability, cell viability, extracellular matrix formation and tissue histology were assessed and discussed, and it was concluded that CNT-reinforced vascular conduits provided a foundation for mechanically appealing constructs where CNTs could be replaced with natural protein nanofibers for further integration of these conduits in large-scale tissue fabrication.

  4. Novel technique for airless connection of artificial heart to vascular conduits.

    Science.gov (United States)

    Karimov, Jamshid H; Gao, Shengqiang; Dessoffy, Raymond; Sunagawa, Gengo; Sinkewich, Martin; Grady, Patrick; Sale, Shiva; Moazami, Nader; Fukamachi, Kiyotaka

    2017-12-01

    Successful implantation of a total artificial heart relies on multiple standardized procedures, primarily the resection of the native heart, and exacting preparation of the atrial and vascular conduits for pump implant and activation. Achieving secure pump connections to inflow/outflow conduits is critical to a successful outcome. During the connection process, however, air may be introduced into the circulation, traveling to the brain and multiple organs. Such air emboli block blood flow to these areas and are detrimental to long-term survival. A correctly managed pump-to-conduit connection prevents air from collecting in the pump and conduits. To further optimize pump-connection techniques, we have developed a novel connecting sleeve that enables airless connection of the Cleveland Clinic continuous-flow total artificial heart (CFTAH) to the conduits. In this brief report, we describe the connecting sleeve design and our initial results from two acute in vivo implantations using a scaled-down version of the CFTAH.

  5. The Effects of Losartan in Preserving the Structural Integrity of Decellularized Small Diameter Vascular Allograft Conduit Implants In Vivo.

    Science.gov (United States)

    Lee, Seung Hyun; Lee, Byoung Wook; Kim, Seong Who; Choo, Suk Jung

    2017-01-01

    Decellularization is a proposed method of preparing nonautologous biological arterial vascular scaffolding; however, the fate of the supporting medial elastic fiber, which is important in preserving the vascular structural integrity, is uncertain. The influence of losartan on preserving the medial elastic fiber integrity in decellularized small diameter vascular conduits (SDVC) was investigated. Decellularized infrarenal abdominal aortic allografts were implanted in Sprague-Dawley rats treated either with (study rats, n = 6) or without oral losartan (control rats, n = 6) and graded 8 weeks later according to a remodeling scoring system (1-mild, 2-moderate, 3-severe) which we devised based on the intimal hyperplasia degree, morphologic changes, and elastic fiber fragmentation of the conduits. DAPI immunohistochemistry analysis was performed in 47 (25 decellularization only and 22 losartan treatment) cross-sectional slide specimens. The losartan versus decellularization only SDVC showed a significantly lower medial elastic fragmentation score (1.32 vs. 2.24, P losartan may yield superior medial layer elastic fiber preservation. © 2016 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

  6. The use of prosthetic grafts in complex military vascular trauma: a limb salvage strategy for patients with severely limited autologous conduit.

    Science.gov (United States)

    Vertrees, Amy; Fox, Charles J; Quan, Reagan W; Cox, Mitchell W; Adams, Eric D; Gillespie, David L

    2009-04-01

    The use of prosthetic grafts for reconstruction of military vascular trauma has been consistently discouraged. In the current conflict, however, the signature wound involves multiple extremities with significant loss of soft tissue and potential autogenous venous conduits. We reviewed the experience with the use of prosthetic grafts for the treatment of vascular injuries sustained during recent conflicts in Iraq and Afghanistan. Trauma registry records with combat-related vascular injuries repaired using prosthetic grafts were retrospectively reviewed from March 2003 to April 2006. Data collected included age, gender, mechanism of injury, vessel injured, conduit, graft patency, complications, including amputation and eventual outcome of repair. Prosthetic grafts were placed in 14 of 95 (15%) patients undergoing extremity bypass for vascular injuries. Patients were men with an average age of 25 years (range, 19-39 years). All prosthetic grafts in this series were made of polytetrafluoroethylene. Mechanism of injury included blast (n = 6), gunshot wounds (n = 6), and blunt trauma (n = 2), resulting in prosthetic repair of injuries to the superficial femoral (n = 8), brachial (n = 3), common carotid (n = 1), subclavian (n = 1), and axillary (n = 1) arteries. Mean evacuation time from injury to stateside arrival was 7 days (range, 3-9 days). Twelve grafts were placed initially at the time of injury, and two after vein graft blow out with secondary hemorrhage. The mean follow-up period was 427 days (range, 49-1,285 days). Seventy-nine percent of prosthetic grafts stayed patent in the short term, allowing patient stabilization, transport to a stateside facility, and elective revascularization with the remaining autologous vein graft. Three prosthetic grafts were replaced urgently for thrombosis. The remaining seven grafts were replaced electively for severe stenosis (3) or exposure (4) with presumed infection. There were no prosthetic graft blow outs or deaths in this

  7. Analysis and algorithmic generation of hepatic vascular systems.

    Science.gov (United States)

    Schwen, Lars Ole; Preusser, Tobias

    2012-01-01

    A proper geometric model of the vascular systems in the liver is crucial for modeling blood flow, the connection between the organ and the rest of the organism. In vivo imaging does not provide sufficient details, so an algorithmic concept for extending measured vascular tree data is needed such that geometrically realistic structures can be generated. We develop a quantification of similarity in terms of different geometric features. This involves topological Strahler ordering of the vascular trees, statistical testing, and averaging. Invariant features are identified in human clinical in vivo CT scans. Results of the existing "Constrained Constructive Optimization" algorithm are compared to real vascular tree data. To improve bifurcation angles in the algorithmic results, we implement a postprocessing step calibrated to the measured features. This framework is finally applied to generate realistic additional details in a patient-specific hepatic vascular tree data set.

  8. Severely regurgitant left ventricle to ascending aorta conduit in a failing fontan patient treated with a vascular endograft and melody transcatheter pulmonary valve via hybrid approach.

    Science.gov (United States)

    Boe, Brian A; Rectenwald, John E; Bocks, Martin L

    2016-12-01

    A 28-year-old male with single ventricular heart disease status post Fontan palliation and subsequent placement of left ventricle to ascending aorta (LV-AAo) valved conduit developed ascites and edema. Diagnostic catheterization revealed elevated ventricular end diastolic pressures (EDP) secondary to severe LV-AAo conduit regurgitation. Given the unique anatomy, surgical access via the right axillary artery provided optimal route for transcatheter valve implantation within the conduit. The procedure resulted in significant hemodynamic improvement with no complications. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  9. Collagen nerve conduits promote enhanced axonal regeneration, schwann cell association, and neovascularization compared to silicone conduits.

    Science.gov (United States)

    Kemp, Stephen W P; Syed, Shahbaz; Walsh, Walsh; Zochodne, Douglas W; Midha, Rajiv

    2009-08-01

    Peripheral nerve regeneration within guidance conduits involves a critical association between regenerating axons, Schwann cells (SCs), and neovascularization. However, it is currently unknown if there is a greater association between these factors in nonpermeable versus semipermeable nerve guide conduits. We therefore examined this collaboration in both silicone- and collagen-based nerve conduits in both 5- and 10-mm-injury gaps in rat sciatic nerves. Results indicate that collagen conduits promoted enhanced axonal and SC regeneration and association when compared to silicone conduits in the shorter 5-mm-gap model. In addition, collagen tubes displayed enhanced neovascularization over silicone conduits, suggesting that these three factors are intimately related in successful peripheral nerve regeneration. At later time points (1- and 2-month analysis) in a 10-mm-gap model, collagen tubes displayed enhanced axonal regeneration, myelination, and vascularization when compared to silicone-based conduits. Results from these studies suggest that regenerating cables within collagen-based conduits are revascularized earlier and more completely, which in turn enhances peripheral nerve regeneration through these nerve guides as compared to silicone conduits.

  10. The defective protein level of myosin light chain phosphatase (MLCP) in the isolated saphenous vein, as a vascular conduit in coronary artery bypass grafting (CABG), harvested from patients with diabetes mellitus (DM).

    Science.gov (United States)

    Matsuo, Yasuko; Kuwabara, Masachika; Tanaka-Totoribe, Naoko; Kanai, Tasuku; Nakamura, Eisaku; Gamoh, Shuji; Suzuki, Akito; Asada, Yujiro; Hisa, Hiroaki; Yamamoto, Ryuichi

    2011-08-26

    We examined the contractile reactivity to 5-hydroxytryptamine (5-HT) in isolated human saphenous vein (SV), as a vascular conduit in coronary artery bypass grafting (CABG), harvested from patients with diabetes mellitus (DM) and non-DM (NDM). Vascular rings of endothelium-denuded SV were used for functional and biochemical experiments. The vasoconstrictions caused by 5-HT were significantly greater (hyperreactivity) in the DM group than in the NDM group. RhoA/ROCK pathway is activated by various G-protein-coupled receptor agonists and consequently induces phosphorylation of myosin phosphatase target subunit 1 (MYPT1), a subunit of myosin light chain phosphatase (MLCP), which inhibits MLCP activity. In the resting state of the vessels, total tissue protein levels of 5-HT(2A) receptor, 5-HT(1B) receptor, RhoA, ROCK1, and ROCK2 did not differ between NDM and DM groups. However, the total protein level of MYPT1 was significantly lower in the DM group than in the NDM group. Furthermore, the ratio of P(Thr(696))-MYPT1 to total MYPT1 was significantly higher in the DM group than in the NDM group. These results suggest that the hyperreactivity to 5-HT in the SV smooth muscle of patients with DM is due to not only enhanced phosphorylation of MLCP but also defective protein level of MLCP. Thus, we reveal for the first time that the defective protein level of MLCP in the DM group can partially explain the poor patency of SV graft harvested from patients with DM. Copyright © 2011 Elsevier Inc. All rights reserved.

  11. Pumped Storage and Potential Hydropower from Conduits

    Energy Technology Data Exchange (ETDEWEB)

    none,

    2015-02-25

    Th is Congressional Report, Pumped Storage Hydropower and Potential Hydropower from Conduits, addresses the technical flexibility that existing pumped storage facilities can provide to support intermittent renewable energy generation. This study considered potential upgrades or retrofit of these facilities, the technical potential of existing and new pumped storage facilities to provide grid reliability benefits, and the range of conduit hydropower opportunities available in the United States.

  12. Code de conduite

    International Development Research Centre (IDRC) Digital Library (Canada)

    irocca

    son point de vue, dans un esprit d'accueil et de respect. NOTRE CODE DE CONDUITE. Le CRDI s'engage à adopter un comportement conforme aux normes d'éthique les plus strictes dans toutes ses activités. Le Code de conduite reflète notre mission, notre philosophie en matière d'emploi et les résultats des discussions ...

  13. Fractal Branching in Vascular Trees and Networks by VESsel GENeration Analysis (VESGEN)

    Science.gov (United States)

    Parsons-Wingerter, Patricia A.

    2016-01-01

    Vascular patterning offers an informative multi-scale, fractal readout of regulatory signaling by complex molecular pathways. Understanding such molecular crosstalk is important for physiological, pathological and therapeutic research in Space Biology and Astronaut countermeasures. When mapped out and quantified by NASA's innovative VESsel GENeration Analysis (VESGEN) software, remodeling vascular patterns become useful biomarkers that advance out understanding of the response of biology and human health to challenges such as microgravity and radiation in space environments.

  14. Conduit purging device and method

    Science.gov (United States)

    Wilks, Michael T. (Inventor)

    2011-01-01

    A device for purging gas comprises a conduit assembly defining an interior volume. The conduit assembly comprises a first conduit portion having an open first end and an open second end and a second conduit portion having an open first end and a closed second end. The open second end of the first conduit portion is disposed proximate to the open first end of the second conduit portion to define a weld region. The device further comprises a supply element supplying a gas to the interior volume at a substantially constant rate and a vent element venting the gas from the interior volume at a rate that maintains the gas in the interior volume within a pressure range suitable to hold a weld bead in the weld region in equilibrium during formation of a weld to join the first conduit portion and the second conduit portion.

  15. A generative modeling approach to connectivity-Electrical conduction in vascular networks

    DEFF Research Database (Denmark)

    Hald, Bjørn Olav

    2016-01-01

    generative approach to connectivity based on the observation that biological organization is hierarchical and composed of a limited set of building blocks, i.e. a vascular network consists of blood vessels which in turn are composed by one or more cell types. Fast electrical communication is crucial...... to synchronize vessel tone across the vast distances within a network. We hypothesize that electrical conduction capacity is delimited by the size of vascular structures and connectivity of the network. Generation and simulation of series of dynamical models of electrical spread within vascular networks...... of different size and composition showed that (1) Conduction is enhanced in models harboring long and thin endothelial cells that couple preferentially along the longitudinal axis. (2) Conduction across a branch point depends on endothelial connectivity between branches. (3) Low connectivity sub...

  16. Seal between metal and ceramic conduits

    Energy Technology Data Exchange (ETDEWEB)

    Underwood, Richard Paul; Tentarelli, Stephen Clyde

    2015-02-03

    A seal between a ceramic conduit and a metal conduit of an ion transport membrane device consisting of a sealing surface of ceramic conduit, a sealing surface of ceramic conduit, a single gasket body, and a single compliant interlayer.

  17. VESsel GENeration Analysis (VESGEN): Innovative Vascular Mappings for Astronaut Exploration Health Risks and Human Terrestrial Medicine

    Science.gov (United States)

    Parsons-Wingerter, Patricia; Kao, David; Valizadegan, Hamed; Martin, Rodney; Murray, Matthew C.; Ramesh, Sneha; Sekaran, Srinivaas

    2017-01-01

    Currently, astronauts face significant health risks in future long-duration exploration missions such as colonizing the Moon and traveling to Mars. Numerous risks include greatly increased radiation exposures beyond the low earth orbit (LEO) of the ISS, and visual and ocular impairments in response to microgravity environments. The cardiovascular system is a key mediator in human physiological responses to radiation and microgravity. Moreover, blood vessels are necessarily involved in the progression and treatment of vascular-dependent terrestrial diseases such as cancer, coronary vessel disease, wound-healing, reproductive disorders, and diabetes. NASA developed an innovative, globally requested beta-level software, VESsel GENeration Analysis (VESGEN) to map and quantify vascular remodeling for application to astronaut and terrestrial health challenges. VESGEN mappings of branching vascular trees and networks are based on a weighted multi-parametric analysis derived from vascular physiological branching rules. Complex vascular branching patterns are determined by biological signaling mechanisms together with the fluid mechanics of multi-phase laminar blood flow.

  18. Oscillation of Angiogenesis with Vascular Dropout in Diabetic Retinopathy by VESsel GENeration Analysis (VESGEN)

    Science.gov (United States)

    Parsons-Wingerter, Patricia; Radbakrishnan, Krisbnan; Vickerman, Mary B.; Kaiser, Peter K.

    2010-01-01

    PURPOSE. Vascular dropout and angiogenesis are hallmarks of the progression of diabetic retinopathy (DR). However, current evaluation of DR relies on grading of secondary vascular effects, such as microaneurysms and hemorrhages, by clinical examination instead of by evaluation of actual vascular changes. The purpose of this study was to map and quantify vascular changes during progression of DR by VESsel GENeration Analysis (VESGEN). METHODS. In this prospective cross-sectional study, 15 eyes with DR were evaluated with fluorescein angiography (FA) and color fundus photography, and were graded using modified Early Treatment Diabetic Retinopathy Study criteria. FA images were separated by semiautomatic image processing into arterial and venous trees. Vessel length density (L(sub v)), number density (N(sub v)), and diameter (D(sub v)) were analyzed in a masked fashion with VESGEN software. Each vascular tree was automatically segmented into branching generations (G(sub 1)...G(sub 8) or G(sub 9)) by vessel diameter and branching. Vascular remodeling status (VRS) for N(sub v) and L(sub v) was graded 1 to 4 for increasing severity of vascular change. RESULTS. By N(sub v) and L(sub v), VRS correlated significantly with the independent clinical diagnosis of mild to proliferative DR (13/15 eyes). N(sub v) and L(sub v) of smaller vessels (G(sub >=6) increased from VRS1 to VRS2 by 2.4 X and 1.6 X, decreased from VRS2 to VRS3 by 0.4 X and 0.6X, and increased from VRS3 to VRS4 by 1.7 X and 1.5 X (P < 0.01). Throughout DR progression, the density of larger vessels (G(sub 1-5)) remained essentially unchanged, and D(sub v1-5) increased slightly. CONCLUSIONS. Vessel density oscillated with the progression of DR. Alternating phases of angiogenesis/neovascularization and vascular dropout were dominated first by remodeling of arteries and subsequently by veins.

  19. Conduit Coating Abrasion Testing

    Science.gov (United States)

    Sullivan, Mary K.

    2013-01-01

    During my summer internship at NASA I have been working alongside the team members of the RESTORE project. Engineers working on the RESTORE project are creating ·a device that can go into space and service satellites that no longer work due to gas shortage or other technical difficulties. In order to complete the task of refueling the satellite a hose needs to be used and covered with a material that can withstand effects of space. The conduit coating abrasion test will help the researchers figure out what type of thermal coating to use on the hose that will be refueling the satellites. The objective of the project is to determine whether or not the conduit coating will withstand the effects of space. For the RESTORE project I will help with various aspects of the testing that needed to be done in order to determine which type of conduit should be used for refueling the satellite. During my time on the project I will be assisting with wiring a relay board that connected to the test set up by soldering, configuring wires and testing for continuity. Prior to the testing I will work on creating the testing site and help write the procedure for the test. The testing will take place over a span of two weeks and lead to an informative conclusion. Working alongside various RESTORE team members I will assist with the project's documentation and records. All in all, throughout my internship at NASA I hope to learn a number of valuable skills and be a part of a hard working team of engineers.

  20. Therapeutic Potential of the Nitrite-Generated NO Pathway in Vascular Dysfunction

    Science.gov (United States)

    Madigan, Michael; Zuckerbraun, Brian

    2013-01-01

    Nitric oxide (NO) generated through L-arginine metabolism by endothelial nitric oxide synthase (eNOS) is an important regulator of the vessel wall. Dysregulation of this system has been implicated in various pathological vascular conditions, including atherosclerosis, angiogenesis, arteriogenesis, neointimal hyperplasia, and pulmonary hypertension. The pathophysiology involves a decreased bioavailability of NO within the vessel wall by competitive utilization of L-arginine by arginase and “eNOS uncoupling.” Generation of NO through reduction of nitrate and nitrite represents an alternative pathway that may be utilized to increase the bioavailability of NO within the vessel wall. We review the therapeutic potential of the nitrate/nitrite/NO pathway in vascular dysfunction. PMID:23847616

  1. The Short Saphenous Vein: A Viable Alternative Conduit for ...

    African Journals Online (AJOL)

    A wide variety of vascular conduits including the. Internal Mammary Artery (IMA), Radial Artery. (RA) and the Long Saphenous Vein (LSV), are available to the Cardiac Surgeon performing Coronary. Artery Bypass Graft procedures. These have demonstrated various successes over the years in both long-term patency.

  2. Generation of Vascular Graft Biomaterials via the Modification of Polyurethane with Hyaluronic Acid

    Science.gov (United States)

    Ruiz, Amaliris

    Cardiovascular disease is the leading cause of mortality in the United States, necessitating surgical interventions such as small diameter (I.D. <6 mm) bypass grafting. Although the use of autologous veins as small diameter grafts produces favorable results, their limited availability provides a significant obstacle. Meanwhile, several synthetic materials have demonstrated success as large-diameter vascular grafts, but exhibit poor patency and high failure rates in small-diameter applications. Based on these limitations and the clinical issues associated with them, it is clear that there is a significant need to develop new materials for cardiovascular and blood-contacting applications that could be used to fabricate small-diameter vascular grafts. Thus, in this thesis we have designed and characterized a new polymer that is composed of both synthetic and natural elements with the goal of generating a material that is appropriate for use in cardiovascular applications. Specifically, we describe the modification of polyurethane (PU), a synthetic polymer with many favorable physical characteristics, with hyaluronic acid (HA), a native glycosaminoglycan that possesses anti-thrombotic properties as well as the ability to modulate endothelial cell proliferation in a molecular weight-dependent manner. The goal of the present work was to assess in detail the impact of 1) HA molecular weight, 2) HA quantity, and 3) the method of HA incorporation (bulk vs. surface-grafted) on the vascular-specific performance of polyurethane-HA (PU-HA) materials, under static conditions and upon exposure to physiological shear stresses. The initial findings presented in this thesis indicate that these PU-HA materials possess many of the physical and biological properties that are necessary for implementation in vascular applications. These materials were able to simultaneously address the three major design criteria in vascular graft fabrication: hemocompatibility, endothelialization, and

  3. Assessment of conduit artery vasomotion using photoplethysmography

    Science.gov (United States)

    Kanders, Karlis; Grabovskis, Andris; Marcinkevics, Zbignevs; Aivars, Juris Imants

    2013-11-01

    Vasomotion is a spontaneous oscillation of vascular tone. The phenomenon has been observed in small arterioles and capillaries as well as in the large conduit arteries. The layer of smooth muscle cells that surrounds a blood vessel can spontaneously and periodically change its tension and thereby the arterial wall stiffness also changes. As the understanding of the phenomenon is still rather obscure, researchers would benefit from a low-cost and reliable investigation technique such as photoplethysmography (PPG). PPG is an optical blood pulsation measurement technique that can offer substantial information about the arterial stiffness. The aims of this pilot study were to evaluate the usefulness of the PPG technique in the research of vasomotion and to investigate vasomotion in the relatively large conduit arteries. Continuous 15 minute long measurements of posterior tibial artery wall stiffness were taken. Artery diameter, electrocardiogram, blood pressure and respiration were also simultaneously registered. Fast Fourier Transform power spectra were calculated to identify unique stiffness oscillations that did not correspond to fluctuations in the systemic parameters and thus would indicate vasomotion. We concluded that photoplethysmography is a convenient method for the research of the vasomotion in large arteries. Local stiffness parameter b/a is more accurate to use and easier to measure than the pulse wave velocity which describes stiffness of a segment of an artery. Conduit arteries might exhibit a low amplitude high frequency vasomotion ( 9 to 27 cycles per minute). Low frequency vasomotion is problematic to distinguish from the passive oscillations imposed by the arterial pressure.

  4. Vascular Cures

    Science.gov (United States)

    ... is the first national program to bring the power of the patient to vascular research and care. ... Our recent national Vascular Research Summit brought together leaders from 31 institutions to generate collaborative projects for ...

  5. Generation of a vascularized organoid using skeletal muscle as the inductive source.

    LENUS (Irish Health Repository)

    Messina, Aurora

    2005-09-01

    The technology required for creating an in vivo microenvironment and a neovasculature that can grow with and service new tissue is lacking, precluding the possibility of engineering complex three-dimensional organs. We have shown that when an arterio-venous (AV) loop is constructed in vivo in the rat groin, and placed inside a semisealed chamber, an extensive functional vasculature is generated. To test whether this unusually angiogenic environment supports the survival and growth of implanted tissue or cells, we inserted various preparations of rat and human skeletal muscle. We show that after 6 weeks incubation of muscle tissue, the chamber filled with predominantly well-vascularized recipient-derived adipose tissue, but some new donor-derived skeletal muscle and connective tissue were also evident. When primary cultured myoblasts were inserted into the chamber with the AV loop, they converted to mature striated muscle fibers. Furthermore, we identify novel adipogenesis-inducing properties of skeletal muscle. This represents the first report of a specific three-dimensional tissue grown on its own vascular supply.

  6. Spatial distribution and packing of xylem conduits.

    Science.gov (United States)

    Martínez-Vilalta, Jordi; Mencuccini, Maurizio; Alvarez, Xavier; Camacho, Juan; Loepfe, Lasse; Piñol, Josep

    2012-07-01

    The hydraulic properties of the xylem determine the ability of plants to transport water from the soil to the leaves and to cope with important stress factors such as frost and drought. Hydraulic properties have usually been studied as a function of the anatomy of xylem conduits and their pits, but recent studies have proposed that system-level properties, related to the topology of the xylem network, may also play a role. Here we study how the spatial arrangement of conduits in xylem cross sections affects the relationship between mean conduit lumen area and conduit density (packing function) across species. Point pattern analysis was used to describe the spatial distribution of xylem conduits in 97 woody species. The effect of conduit aggregation on the packing function was tested using phylogenetic generalized least squares. A hydraulic model with an explicit description of the topology of the xylem network was used to interpret the functional significance of our findings. The spatial arrangement of conduits affected the packing function across species, so that species with aggregated distributions tended to have lower conduit densities for a given conduit size and lower conduit lumen fractions. According to our modeling results, the higher conduit-to-conduit connectivity of species with aggregated distributions allows them to achieve higher hydraulic conductivity. Species with aggregated conduits, however, pay a cost in terms of increased vulnerability to embolism. The spatial arrangement of conduits affects the fundamental structural and functional attributes of the xylem.

  7. Ash production by attrition in volcanic conduits and plumes.

    Science.gov (United States)

    Jones, T J; Russell, J K

    2017-07-17

    Tephra deposits result from explosive volcanic eruption and serve as indirect probes into fragmentation processes operating in subsurface volcanic conduits. Primary magmatic fragmentation creates a population of pyroclasts through volatile-driven decompression during conduit ascent. In this study, we explore the role that secondary fragmentation, specifically attrition, has in transforming primary pyroclasts upon transport in volcanic conduits and plumes. We utilize total grain size distributions from a suite of natural and experimentally produced tephra to show that attrition is likely to occur in all explosive volcanic eruptions. Our experimental results indicate that fine ash production and surface area generation is fast (eruption column stability, tephra dispersal, aggregation, volcanic lightening generation, and has concomitant effects on aviation safety and Earth's climate.

  8. Construction and biofunctional evaluation of electrospun vascular graft loaded with selenocystamine for in situ catalytic generation of nitric oxide

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Siyuan; An, Jun; Weng, Lei [State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Bioactive Materials for Ministry of Education, College of Life Sciences, Nankai University, Tianjin 300071 (China); Li, Yandong [Institute of Polymer Chemistry, College of Chemistry, Nankai University, Tianjin 300071 (China); Xu, Han; Wang, Yaping; Ding, Dan; Kong, Deling [State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Bioactive Materials for Ministry of Education, College of Life Sciences, Nankai University, Tianjin 300071 (China); Wang, Shufang, E-mail: wangshufang@nankai.edu.cn [State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Bioactive Materials for Ministry of Education, College of Life Sciences, Nankai University, Tianjin 300071 (China)

    2014-12-01

    Construction and biofunctional evaluation of a novel vascular graft with in situ catalytic generation of nitric oxide were described in this paper. Poly α-lysine and poly (γ-glutamic acid) were deposited alternately onto the surface of an electrospun poly ε-caprolactone matrix via electrostatic layer-by-layer self-assembly, and then selenocystamine was loaded as a catalyst. Measurement of in vitro catalytic generation of nitric oxide demonstrated that this catalyst-loaded material could considerably accelerate the release of nitric oxide from S-nitrosoglutathione. A fibroblast proliferation assay showed that the material possessed satisfactory cellular compatibility. The catalyst-loaded material could inhibit the spread of smooth muscle cells in the presence of nitric oxide donors. In arteriovenous-shunt experiment, the catalyst-loaded graft exhibited good anti-thrombotic property where it could prevent acute thrombosis by decreasing the adhesion and activation of platelets and other blood cells. These data suggest a new method of building vascular grafts with improved hemocompatibility and biological functions. - Highlights: • A porous small-diameter vascular graft was prepared by electrospinning. • Selenocystamine was loaded for in situ catalytic and sustained NO generation. • There was a significant catalytic NO generation on the catalyst-loaded sample. • The spread of smooth muscle cells was inhibited on the catalyst-loaded sample. • The catalyst-loaded sample showed anti-thrombotic property in AV-shunt experiment.

  9. Factors affecting career choice among the next generation of academic vascular surgeons.

    Science.gov (United States)

    Danczyk, Rachel C; Sevdalis, Nick; Woo, Karen; Hingorani, Anil P; Landry, Gregory J; Liem, Timothy K; Moneta, Gregory L; Mitchell, Erica L

    2012-05-01

    Few studies have examined factors that influence an individual's decision to enter an academic medical career after residency training. We sought to evaluate whether sex, ethnicity, child care issues, and debt burden influenced residents' choice for a career in academic vascular surgery. A 39-item Web survey, designed to elucidate which factors motivated residents to seek a career in academic vascular surgery, was sent to 295 vascular surgery residents currently enrolled in Accreditation Council on Graduate Medical Education-accredited training programs. A total of 128 responses (43%) were received. Of these, 53% of respondents were white and 47% were nonwhite and 34 (27%) were women and 94 (73%) were men. Fifty-seven percent of minorities anticipate a career in academic vascular surgery. There were no statistical differences between sex and ethnicity for factors influencing career choice, including training paradigm, presence of a life partner or dependents, mentorship role, participation in research, service, and teaching, anticipated salary, and debt burden (P > .05). Seventy-seven percent of respondents carry significant debt; of those with debt, 81% owe >$100,000 and 40% owe >$200,000. Seventy-three percent of 0+5 trainees anticipated choosing an academic practice compared with 42% of 5+2 trainees (P academic career cited procedural variation, breadth and depth of practice/tertiary referral experience, and research opportunities as the most important drivers of career choice. Income potential, strength of the job market, and child care needs were deemed less important. This study shows that academic vascular surgery is a popular career option for current vascular surgery trainees, especially those in 0+5 programs. Choosing a career in academic vascular surgery appears not to be influenced by sex, ethnicity, child care concerns, salary expectations, or debt burden, even though most trainees carry enormous debt. The data imply future academic vascular surgeons

  10. Peripheral nerve conduits: technology update

    Directory of Open Access Journals (Sweden)

    Arslantunali D

    2014-12-01

    Full Text Available D Arslantunali,1–3,* T Dursun,1,2,* D Yucel,1,4,5 N Hasirci,1,2,6 V Hasirci,1,2,7 1BIOMATEN, Center of Excellence in Biomaterials and Tissue Engineering, Middle East Technical University (METU, Ankara, Turkey; 2Department of Biotechnology, METU, Ankara, Turkey; 3Department of Bioengineering, Gumushane University, Gumushane, Turkey; 4Faculty of Engineering, Department of Medical Engineering, Acibadem University, Istanbul, Turkey; 5School of Medicine, Department of Histology and Embryology, Acibadem University, Istanbul, Turkey; 6Department of Chemistry, Faculty of Arts and Sciences, METU, Ankara, Turkey; 7Department of Biological Sciences, Faculty of Arts and Sciences, METU, Ankara, Turkey *These authors have contributed equally to this work Abstract: Peripheral nerve injury is a worldwide clinical problem which could lead to loss of neuronal communication along sensory and motor nerves between the central nervous system (CNS and the peripheral organs and impairs the quality of life of a patient. The primary requirement for the treatment of complete lesions is a tension-free, end-to-end repair. When end-to-end repair is not possible, peripheral nerve grafts or nerve conduits are used. The limited availability of autografts, and drawbacks of the allografts and xenografts like immunological reactions, forced the researchers to investigate and develop alternative approaches, mainly nerve conduits. In this review, recent information on the various types of conduit materials (made of biological and synthetic polymers and designs (tubular, fibrous, and matrix type are being presented. Keywords: peripheral nerve injury, natural biomaterials, synthetic biomaterials

  11. 47 CFR 32.2441 - Conduit systems.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Conduit systems. 32.2441 Section 32.2441 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES UNIFORM SYSTEM OF ACCOUNTS FOR TELECOMMUNICATIONS COMPANIES Instructions for Balance Sheet Accounts § 32.2441 Conduit systems. (a...

  12. Stability of volcanic conduits during explosive eruptions

    Science.gov (United States)

    Aravena, Álvaro; de'Michieli Vitturi, Mattia; Cioni, Raffaello; Neri, Augusto

    2017-06-01

    Geological evidences of volcanic conduit widening are common in most pyroclastic deposits (e.g. presence of lithic fragments from different depths), suggesting a continuous modification of the conduit geometry during volcanic eruptions. However, the controlling factors of the mechanisms driving conduit enlargement (e.g. erosion, local collapse) are still partially unclear, as well as the influence of conduit geometry on the eruptive dynamics. Although numerical models have been systematically employed to study volcanic conduits, their mechanical stability and the eruptive dynamics related to non-cylindrical conduits have been poorly addressed. We present here a 1D steady-state model which includes the main processes experimented by ascending magmas (i.e. crystallization, rheological changes, fragmentation, drag forces, outgassing and degassing), and the application of two mechanical stability criteria (Mohr-Coulomb and Mogi-Coulomb), in order to study the collapse conditions of volcanic conduits during a representative explosive rhyolitic eruption. It emerges that mechanical stability of volcanic conduits is mainly controlled by its radial dimension, and a minimum radius for reaching stable conditions can be computed, as a function of water content and inlet overpressure. Additionally, for a set of input parameters thought typical of explosive rhyolitic volcanism, we estimated a minimum magma flux for developing a mechanically stable conduit ( 7 • 107 - 3 • 108 kg/s). Results are consistent with the unsteady character usually observed in sub-Plinian eruptions, opposite to mainly stationary Plinian eruptions, commonly characterized by higher magma discharge rates. We suggest that cylindrical conduits represent a mechanically stable configuration only for large radii. Because the instability conditions are not uniform along the conduit, the widening processes probably lead to conduit geometries with depth-varying width. Consequently, as our model is able to

  13. The Role of Acute Intermittent Hypoxia in Neutrophil-Generated Superoxide, Sympathovagal Balance, and Vascular Function in Healthy Subjects.

    Science.gov (United States)

    Almeida, Germana P L; Trombetta, Ivani C; Cepeda, Felipe X; Hatanaka, Elaine; Curi, Rui; Mostarda, Cristiano; Irigoyen, Maria C; Barreto-Filho, José A S; Krieger, Eduardo M; Consolim-Colombo, Fernanda M

    2017-01-01

    Introduction: Recurrent hypoxia (HPX), a hallmark of the obstructive sleep apnea (OSA), impairs autonomic balance, and increases arterial blood pressure (BP). Oxidative stress is one of the mechanisms involved in these alterations. The cumulative effect of acute intermittent HPX and the chronicity may determine whether the response crosses the threshold from having protective value to pathology. However, the impact of acute intermittent HPX-reoxygenation on markers of oxidative stress in healthy individuals remains to be fully understood. Objective: To analyze the effects of the acute intermittent HPX on the generation of neutrophil-derived superoxide, sympathovagal balance, and vascular function in healthy subjects. Methods: We applied six cycles of intermittent HPX (10% O2 and 90% N2) for 5 min followed by 2 min of room-air in 15 healthy volunteers (34 ± 2 years; 22.3 ± 0.46 kg/m(2)), without OSA (polysomnography), during wakefulness. During the experimental protocol, we recorded O2 saturation, end-tidal CO2, heart rate (HR), systolic, and diastolic BP, cardiac output (CO) and peripheral resistance (PR). Cardiac sympathovagal balance was determined by HR variability analysis (low frequency and high frequency bands, LF/HF). Superoxide generation in polymorphonuclear neutrophil cells were established using relative luminescence units (PMNs RLU) at baseline (pre-HPX) and immediately after hypoxia induction (post-HPX6). Results: The studied subjects had normal levels of BP, plasma glucose, lipid profile, and inflammatory marker (C-reactive protein). Acute intermittent HPX increased HR, systolic BP, CO, and decreased PR. Additionally, acute intermittent HPX increased PMNs RLU, measured post-HPX6 (470 ± 50 vs. 741 ± 135, P intermittent HPX not only increased superoxide generation in neutrophils, but also impaired cardiac sympathovagal balance in healthy subjects. These data reinforce the role of intermittent HPX in superoxide generation on neutrophils, which may

  14. Implication of Free Fatty Acids in Thrombin Generation and Fibrinolysis in Vascular Inflammation in Zucker Rats and Evolution with Aging

    Directory of Open Access Journals (Sweden)

    Jérémy Lagrange

    2017-11-01

    Full Text Available Background: The metabolic syndrome (MetS and aging are associated with modifications in blood coagulation factors, vascular inflammation, and increased risk of thrombosis.Objectives: Our aim was to determine concomitant changes in thrombin generation in the blood compartment and at the surface of vascular smooth muscle cells (VSMCs and its interplay with adipokines, free fatty acids (FFA, and metalloproteinases (MMPs in obese Zucker rats that share features of the human MetS.Methods: Obese and age-matched lean Zucker rats were compared at 25 and 80 weeks of age. Thrombin generation was assessed by calibrated automated thrombography (CAT.Results: Endogenous thrombin potential (ETP was increased in obese rats independent of platelets and age. Clot half-lysis time was delayed with obesity and age. Interleukin (IL-1β and IL-13 were increased with obesity and age respectively. Addition of exogenous fibrinogen, leptin, linoleic, or palmitic acid increased thrombin generation in plasma whereas adiponectin had an opposite effect. ETP was increased at the surface of VSMCs from obese rats and addition of exogenous palmitic acid further enhanced ETP values. Gelatinase activity was increased in aorta at both ages in obese rats and MMP-2 activity was increased in VSMCs from obese rats.Conclusions: Our study demonstrated in MetS an early prothrombotic phenotype of the blood compartment reinforced by procoagulant properties of dedifferentiated and inflammatory VSMCs. Mechanisms involved (1 increased fibrinogen and impaired fibrinolysis and (2 increased saturated fatty acids responsible for additive procoagulant effects. Whether specifically targeting this hypercoagulability using direct thrombin inhibitors would improve outcome in MetS is worth investigating.

  15. NADPH oxidase (NOX) 1 mediates cigarette smoke-induced superoxide generation in rat vascular smooth muscle cells.

    Science.gov (United States)

    Chang, Kyung-Hwa; Park, Jung-Min; Lee, Chang Hoon; Kim, Bumseok; Choi, Kyung-Chul; Choi, Seong-Jin; Lee, Kyuhong; Lee, Moo-Yeol

    2017-02-01

    Smoking is a well-established risk factor for cardiovascular diseases. Oxidative stress is one of the common etiological factors, and NADPH oxidase (NOX) has been suggested as a potential mediator of oxidative stress. In this study, cigarette smoke (CS)-induced superoxide production was characterized in vascular smooth muscle cells (VSMC). CS was prepared in forms of cigarette smoke extract (CSE) and total particulate matter (TPM). Several molecular probes for reactive oxygen species were trialed, and dihydroethidium (DHE) and WST-1 were chosen for superoxide detection considering the autofluorescence, light absorbance, and peroxidase inhibitory activity of CS. Both CSE and TPM generated superoxide in a VSMC culture system by stimulating cells to produce superoxide and by directly producing superoxide in the aqueous solution. NOX, specifically NOX1 was found to be an important cellular source of superoxide through experiments with the NOX inhibitors diphenyleneiodonium (DPI) and VAS2870 as well as isoform-specific NOX knockdown. NOX inhibitors and the superoxide dismutase mimetic TEMPOL reduced the cytotoxicity of CSE, thus suggesting the contribution of NOX1-derived superoxide to cytotoxicity. Since NOX1 is known to mediate diverse pathological processes in the vascular system, NOX1 may be a critical effector of cardiovascular toxicity caused by smoking. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. H2O2 generated from mitochondrial electron transport chain in thoracic perivascular adipose tissue is crucial for modulation of vascular smooth muscle contraction.

    Science.gov (United States)

    Costa, Rafael M; Filgueira, Fernando P; Tostes, Rita C; Carvalho, Maria Helena C; Akamine, Eliana H; Lobato, Nubia S

    2016-09-01

    The perivascular adipose tissue (PVAT) releases a variety of factors that affect vascular function. PVAT in the thoracic aorta shares characteristics with the brown adipose tissue, including a large amount of mitochondria. PVAT-derived factors influence both endothelial and smooth muscle function via several signaling mechanisms including the release/generation of reactive nitrogen and oxygen species. Considering the importance of reactive oxygen species (ROS) on vascular function and that mitochondria are an important source of ROS, we hypothesized that mitochondria-derived ROS in the PVAT modulates vascular reactivity. Vascular reactivity to norephinephrine (NE) was evaluated in thoracic aortic rings, with or without endothelium and/or PVAT, from male Wistar rats. Mitochondrial uncoupling, as well as hydrogen peroxide (H2O2) removal, increased the contraction in vessels surrounded by PVAT. PVAT stimulated with NE exhibited increased protein expression, determined by Western blot analysis, of manganese superoxide dismutase (Mn-SOD) and decreased protein expression of catalase. Ultimately, NE increased superoxide anion (O2(-)) generation in PVAT via increases in intracellular calcium. These results clearly demonstrate that mitochondrial electron transport chain (mETC) in PVAT contributes to modulation of aortic muscle contraction by generating higher amounts of O2(-) that is, in turn, dismutated to hydrogen peroxide, which then acts as a pivotal signaling molecule regulating vascular smooth muscle contraction. Copyright © 2015 Elsevier Inc. All rights reserved.

  17. Extrinsic airway compression secondary to pulmonary arterial conduits: MR findings

    Energy Technology Data Exchange (ETDEWEB)

    Donnelly, L.F. [Dept. of Radiology and Div. of Cardiothoracic Surgery, Children`s Hospital Medical Center, Cincinnati, OH (United States); Strife, J.L. [Dept. of Radiology and Div. of Cardiothoracic Surgery, Children`s Hospital Medical Center, Cincinnati, OH (United States); Bailey, W.W. [Dept. of Radiology and Div. of Cardiothoracic Surgery, Children`s Hospital Medical Center, Cincinnati, OH (United States)

    1997-03-01

    Abnormal enlargement or malposition of any vascular structure or mass adjacent to the airway can cause extrinsic airway compression. In children with previous surgery for congenitial heart disease, mass effect from prosthetic devices or alteration in the anatomic position of normal structures can lead to extrinsic airway compression. Because many children have complex medical problems after cardiac surgery, wheezing may be attributed to cardiac causes and airway compression may not be investigated. Furthermore, the distal airway compression seen in these children often is not visualized on chest radiographys. MR imaging can be useful in evaluating extrinsic airway compression in these patients. We present the MR imaging of two patients with symptomatic extrinsic airway compression secondary to pulmonary arterial conduits. (orig.)

  18. Can one identify karst conduit networks geometry and properties from hydraulic and tracer test data?

    Science.gov (United States)

    Borghi, Andrea; Renard, Philippe; Cornaton, Fabien

    2016-04-01

    models of karstic systems using flow and transport data. They also suggest that a pragmatic approach for these complex systems could be to generate a large set of karst conduit network realizations using a pseudo-genetic approach such as SKS, and for each karst realization, flow and transport parameters could be optimized using a gradient-based search such as the one implemented in PEST.

  19. Generation and Characterization of Vascular Smooth Muscle Cell Lines Derived from a Patient with a Bicuspid Aortic Valve

    Directory of Open Access Journals (Sweden)

    Pamela Lazar-Karsten

    2016-04-01

    Full Text Available Thoracic aortic dilation is the most common malformation of the proximal aorta and is responsible for 1%–2% of all deaths in industrialized countries. In approximately 50% of patients with a bicuspid aortic valve (BAV, dilation of any or all segments of the aorta occurs. BAV patients with aortic dilation show an increased incidence of cultured vascular smooth muscle cell (VSMC loss. In this study, VSMC, isolated from the ascending aorta of BAV, was treated with Simian virus 40 to generate a BAV-originated VSMC cell line. To exclude any genomic DNA or cross-contamination, highly polymorphic short tandem repeats of the cells were profiled. The cells were then characterized using flow cytometry and karyotyping. The WG-59 cell line created is the first reported VSMC cell line isolated from a BAV patient. Using an RT2 Profiler PCR Array, genes within the TGFβ/BMP family that are dependent on losartan treatment were identified. Endoglin was found to be among the regulated genes and was downregulated in WG-59 cells following treatment with different losartan concentrations, when compared to untreated WG-59 cells.

  20. Testosterone induces apoptosis in vascular smooth muscle cells via extrinsic apoptotic pathway with mitochondria-generated reactive oxygen species involvement.

    Science.gov (United States)

    Lopes, Rheure Alves Moreira; Neves, Karla Bianca; Pestana, Cezar Rangel; Queiroz, André Lima; Zanotto, Camila Ziliotto; Chignalia, Andréia Z; Valim, Yara Maria; Silveira, Leonardo R; Curti, Carlos; Tostes, Rita C

    2014-06-01

    Testosterone exerts both beneficial and harmful effects on the cardiovascular system. Considering that testosterone induces reactive oxygen species (ROS) generation and ROS activate cell death signaling pathways, we tested the hypothesis that testosterone induces apoptosis in vascular smooth muscle cells (VSMCs) via mitochondria-dependent ROS generation. Potential mechanisms were addressed. Cultured VSMCs were stimulated with testosterone (10(-7) mol/l) or vehicle (2-12 h) in the presence of flutamide (10(-5) mol/l), CCCP (10(-6) mol/l), mimetic manganese(III) tetrakis(1-methyl-4-pyridyl)porphyrin (MnTMPyP; 3 × 10(-5) mol/l), Z-Ile-Glu(O-ME)-Thr-Asp(O-Me) fluoromethyl ketone (Z-IETD-FMK; 10(-5) mol/l), or vehicle. ROS were determined with lucigenin and dichlorodihydrofluorescein; apoptosis, with annexin V and calcein; O2 consumption, with a Clark-type electrode, and procaspases, caspases, cytochrome c, Bax, and Bcl-2 levels by immunoblotting. Testosterone induced ROS generation (relative light units/mg protein, 2 h; 162.6 ± 16 vs. 100) and procaspase-3 activation [arbitrary units, (AU), 6 h; 166.2 ± 19 vs. 100]. CCCP, MnTMPyP, and flutamide abolished these effects. Testosterone increased annexin-V fluorescence (AU, 197.6 ± 21.5 vs. 100) and decreased calcein fluorescence (AU, 34.4 ± 6.4 vs. 100), and O2 consumption (nmol O2/min, 18.6 ± 2.0 vs. 34.4 ± 3.9). Testosterone also reduced Bax-to-Bcl-2 ratio but not cytochrome-c release from mitochondria. Moreover, testosterone (6 h) induced cleavage of procaspase 8 (AU, 161.1 ± 13.5 vs. 100) and increased gene expression of Fas ligand (2(ΔΔCt), 3.6 ± 1.2 vs. 0.7 ± 0.5), and TNF-α (1.7 ± 0.4 vs. 0.3 ± 0.1). CCCP, MnTMPyP, and flutamide abolished these effects. These data indicate that testosterone induces apoptosis in VSMCs via the extrinsic apoptotic pathway with the involvement of androgen receptor activation and mitochondria-generated ROS. Copyright © 2014 the American Physiological Society.

  1. Impact of Cyclic Stretch on Induced Elastogenesis Within Collagenous Conduits

    Science.gov (United States)

    Venkataraman, Lavanya; Bashur, Chris A.

    2014-01-01

    In vitro tissue engineering of vascular conduits requires a synergy between several external factors, including biochemical supplementation and mechanotranductive stimulation. The goal of this study was to improve adult human vascular smooth muscle cell orientation and elastic matrix synthesis within 3D tubular collagen gel constructs. We used a combination of elastogenic factors (EFs) previously tested in our lab, along with cyclic circumferential strains at low amplitude (2.5%) delivered at a range of frequencies (0.5, 1.5, and 3 Hz). After 21 days of culture, the constructs were analyzed for elastic matrix outcomes, activity of matrix metalloproteinases (MMPs)-2 and −9, cell densities and phenotype, and mechanical properties of constructs. While cell densities remained unaffected by the addition of stretch, contractile phenotypic markers were elevated in all stretched constructs relative to control. Constructs cultured with EFs stretched at 1.5 Hz exhibited the maximum elastin mRNA expression and total matrix elastin (over sixfold vs. the static EFs control). MMP-2 content was comparable in all treatment conditions, but MMP-9 levels were elevated at the higher frequencies (1.5 and 3 Hz). Minimal circumferential orientation was achieved and the mechanical properties remained comparable among the treatment conditions. Overall, constructs treated with EFs and stretched at 1.5 Hz exhibited the most elastogenic outcomes. PMID:24313750

  2. VASCULAR DEMENTIA

    Directory of Open Access Journals (Sweden)

    Maria Alekseyevna Cherdak

    2010-01-01

    vascular cognitive disorders and vascular dementia (VD. The heterogeneity of vascular cognitive disorders, concurrence of vascular and neurodegenerative diseases are discussed. Data from studies of specific therapy for VD are given.

  3. Acoustic signal propagation characterization of conduit networks

    Science.gov (United States)

    Khan, Muhammad Safeer

    Analysis of acoustic signal propagation in conduit networks has been an important area of research in acoustics. One major aspect of analyzing conduit networks as acoustic channels is that a propagating signal suffers frequency dependent attenuation due to thermo-viscous boundary layer effects and the presence of impedance mismatches such as side branches. The signal attenuation due to side branches is strongly influenced by their numbers and dimensions such as diameter and length. Newly developed applications for condition based monitoring of underground conduit networks involve measurement of acoustic signal attenuation through tests in the field. In many cases the exact installation layout of the field measurement location may not be accessible or actual installation may differ from the documented layout. The lack of exact knowledge of numbers and lengths of side branches, therefore, introduces uncertainty in the measurements of attenuation and contributes to the random variable error between measured results and those predicted from theoretical models. There are other random processes in and around conduit networks in the field that also affect the propagation of an acoustic signal. These random processes include but are not limited to the presence of strong temperature and humidity gradients within the conduits, blockages of variable sizes and types, effects of aging such as cracks, bends, sags and holes, ambient noise variations and presence of variable layer of water. It is reasonable to consider that the random processes contributing to the error in the measured attenuation are independent and arbitrarily distributed. The error, contributed by a large number of independent sources of arbitrary probability distributions, is best described by an approximately normal probability distribution in accordance with the central limit theorem. Using an analytical approach to model the attenuating effect of each of the random variable sources can be very complex and

  4. 78 FR 69403 - South Tahoe Public Utility District; Notice of Preliminary Determination of a Qualifying Conduit...

    Science.gov (United States)

    2013-11-19

    ............ The facility is constructed, operated, or Y maintained for the generation of electric power and uses... qualifying conduit hydropower facility, pursuant to section 30 of the Federal Power Act, as amended by... along the existing C-Line export pipeline in South Tahoe Public Utility District's wastewater treatment...

  5. Detection of EETs and HETE-generating cytochrome P-450 enzymes and the effects of their metabolites on myometrial and vascular function.

    Science.gov (United States)

    Pearson, Timothy; Warren, Averil Y; Barrett, David A; Khan, Raheela N

    2009-09-01

    Cytochrome P-450 (CYP450) enzymes of the CYP2 and -4 family in humans metabolize arachidonic acid to generate bioactive epoxyeicosatrienenoic acids (EETs) and hydroxyeicosatetrenoic acids (HETEs). We report significantly higher levels of CYP 2J2 protein expression following the onset of labor (n = 6, P vascular reactivity (n = 6). Both 12- and 20-HETE (n = 5-6) caused vasoconstriction of partially depolarized blood vessels, with glibenclamide (n = 5) enhancing the effect of 12-HETE alone. Our findings signify a role for CYP2C9/19, -2J2, and -4A11/22 in late pregnancy, possibly related to the synthesis of lipid metabolites and downstream effects on vascular remodeling in the term pregnant uterus. The presence of CYP4A11/22 and their resultant procontractile metabolites could argue either a role in the control and initiation of labor and/or modification of the vascular delivery system to influence blood flow to the laboring uterus. The differential effects of the EETs and HETEs in the pregnant human uterus identify the CYP pathway as a novel modulator of myometrial and vascular physiology during late pregnancy.

  6. Refractory spasm of coronary arteries and grafted conduits after isolated coronary artery bypass surgery.

    Science.gov (United States)

    Lorusso, Roberto; Crudeli, Elena; Lucà, Fabiana; De Cicco, Giuseppe; Vizzardi, Enrico; D'Aloia, Antonio; Gelsomino, Sandro

    2012-02-01

    Refractory vascular spasm (RVS) concomitantly involving the entire coronary artery system and grafted conduits after coronary artery bypass grafting (CABG) surgery is a rare, but dreadful event. No consensus exists in terms of appropriate management. Between 1986 and 2009, 5,762 patients underwent isolated CABG at our institution, and 7 patients experienced RVS involving the coronary arteries and implanted conduits. Mean age was 65.6 years and 3 were female. All patients received from 3 to 5 distal anastomoses, including use of the left internal mammary artery. During the same time period, 18 patients experienced perioperative vasospasm of a single coronary artery or of a grafted conduit. All diffuse RVS events occurred between 3 and 8 hours after surgery. All patients had diffuse ischemic-like electrocardiographic changes, and 5 patients rapidly developed cardiogenic shock in the intensive care unit. Angiography was quickly performed in all patients and showed diffuse RVS involving either the native coronary arteries or the anastomosed arterial and venous conduits. The first 5 patients of this series died in the catheterization lab due to rapidly evolving refractory cardiogenic shock and unresponsive cardiac arrest, despite intraaortic counterpulsation and aggressive pharmacologic interventions (selective vasodilators and systemic inotropes). In the last 2 patients, extracorporeal membrane oxygenation was quickly instituted (1 in the catheterization lab, 1 in the operating room) and RVS could be successfully managed with complete resolution of ongoing vasospasm. In the single vascular spasm, there was only 1 death for refractory cardiac arrest, whereas all the other patients were successfully treated with direct infusion of vasodilators. Diffuse RVS after CABG is a rare but lethal condition. Our experience, although limited, indicates that in such cases an aggressive treatment, that is, prompt extracorporeal membrane oxygenation institution and controlled

  7. Liver Transplantation Utilizing Mixed Biologic and Synthetic Arterial Conduits

    Directory of Open Access Journals (Sweden)

    Marcio F. Chedid

    2016-01-01

    Full Text Available Arterial conduits are necessary in nearly 5% of all liver transplants and are usually constructed utilizing segments of donor iliac artery. However, available segments of donor iliac artery may not be lengthy enough or may not possess enough quality to enable its inclusion in the conduit. Although there are few reports of arterial conduits constructed solely utilizing prosthetic material, no previous reports of conduits composed of a segment of donor iliac artery and prosthetic material (mixed biologic and synthetic arterial conduits were found in the medial literature to date. Two cases reporting successful outcomes after creation of mixed biologic and prosthetic arterial conduits are outlined in this report. Reason for creation of conduits was complete intimal dissection of the recipient’s hepatic artery in both cases. In both cases, available segments of donor iliac artery were not lengthy enough to bridge infrarenal aorta to porta hepatis. Both patients have patent conduits and normally functioning liver allografts, respectively, at 4 and 31 months after transplant. Mixed biologic and synthetic arterial conduits constitute a viable technical option and may offer potential advantages over fully prosthetic arterial conduits.

  8. Efficacy of camera sleeve in conveyance of conduits.

    Science.gov (United States)

    Bharathi, R Saranga

    2017-02-28

    Esophageal substitutes need conveyance from the abdomen into the neck for restoration of alimentary continuity. Reports suggest that the use of plastic camera sleeve may prove advantageous in restoring conveyance. This study aims to evaluate the practicability of this approach, specifically, in laparoscopy-assisted surgeries. The efficacy of camera sleeve in conduit transposition was prospectively evaluated over 2 years. The following parameters were assessed: success/failure; time taken; blood loss; adequacy of length of the conduit delivered into the neck; conduit orientation; ease of procedure through different routes; conduit damage; complications; and drawbacks. The technique was used in 25 consecutive patients. Two ileo-colonic, 13 gastric, and 10 colonic conduits were transposed. Posterior mediastinal, retro-sternal, and ante-sternal routes were used in 15, 8, and 2 cases, respectively. There were no failures. The technique was easy to adopt. It added < 10 minutes to the procedure. It entailed no additional blood loss. Adequate length of the conduit was transposed into the neck, atraumatically. Conduits maintained their orientation without effort. Although no complications per se were associated with its use, extra conduit length became transposed into the neck, twice, necessitating its trimming/adjustment. In one case, traction suture became avulsed from the conduit, midway in the tunnel. This could easily be rectified by pulling out the sleeve from the neck, which brought up the conduit along with it, as desired. Use of camera sleeve proves efficacious in interposition of esophageal substitutes.

  9. Prevention of vascular dysfunction and arterial hypertension in mice generated by assisted reproductive technologies by addition of melatonin to culture media.

    Science.gov (United States)

    Rexhaj, Emrush; Pireva, Agim; Paoloni-Giacobino, Ariane; Allemann, Yves; Cerny, David; Dessen, Pierre; Sartori, Claudio; Scherrer, Urs; Rimoldi, Stefano F

    2015-10-01

    Assisted reproductive technologies (ART) induce vascular dysfunction in humans and mice. In mice, ART-induced vascular dysfunction is related to epigenetic alteration of the endothelial nitric oxide synthase (eNOS) gene, resulting in decreased vascular eNOS expression and nitrite/nitrate synthesis. Melatonin is involved in epigenetic regulation, and its administration to sterile women improves the success rate of ART. We hypothesized that addition of melatonin to culture media may prevent ART-induced epigenetic and cardiovascular alterations in mice. We, therefore, assessed mesenteric-artery responses to acetylcholine and arterial blood pressure, together with DNA methylation of the eNOS gene promoter in vascular tissue and nitric oxide plasma concentration in 12-wk-old ART mice generated with and without addition of melatonin to culture media and in control mice. As expected, acetylcholine-induced mesenteric-artery dilation was impaired (P = 0.008 vs. control) and mean arterial blood pressure increased (109.5 ± 3.8 vs. 104.0 ± 4.7 mmHg, P = 0.002, ART vs. control) in ART compared with control mice. These alterations were associated with altered DNA methylation of the eNOS gene promoter (P culture media prevented eNOS dysmethylation (P = 0.005, vs. ART + vehicle), normalized nitric oxide plasma concentration (23.1 ± 14.6 μM, P = 0.002 vs. ART + vehicle) and mesentery-artery responsiveness to acetylcholine (P culture media prevents ART-induced vascular dysfunction. We speculate that this approach will also allow preventing ART-induced premature atherosclerosis in humans. Copyright © 2015 the American Physiological Society.

  10. Optimization of Design of Steam Turbine Exhaust Conduits

    Directory of Open Access Journals (Sweden)

    A. S. Goldin

    2014-01-01

    Full Text Available Improving effectiveness turbine was and remains a key issue for today. In order to improve the efficiency of the turbine is necessary to reduce losses in the steam turbine exhaust conduit.This paper presents the design optimization exhaust conduit steam turbine K-27-2.9 produced by JSC «KTW» at the design stage. The aims of optimizing the design were: decreasing hydraulic resistance of the conduit, reduction of non-uniformity of the flow at the outlet of the conduit, equalizing steam flow ahead of the condenser tube bundle.The conduit models were made and flows in it were simulated in environment of the Solid Works and its application COSMOS Flo Works.As the initial conduit model was selected exhaust conduit of turbine PT-25/34-3.4 produced by JSC «KTW». Was obtained by the calculated velocity field at the outlet of the conduit. The analysis of the calculation results revealed the necessity of changes to the initial design of the conduit. The changes were accompanied by calculating currents flow in the conduit, and assessed the impact of design changes on the nature of the course. Further transformation of the construction of the conduit was held on the results of these calculations. Construction changes are not touched by the outer geometry of the conduit, and were introduced to meet technological.According to calculation results, conclusions were drawn and selected three versions of the conduit.Given are the research results for the initial conduit model and modified design versions. In order to evaluate the flow degree of irregularity the momentum factor (Bussinesku factor for outlet crosssection of the selected conduit design version. Analysis of the research results made it possible to determine optimum design of the exhaust conduit.Introducing the suggested alterations in the conduit design will result in improvement of heat exchange in the condenser, an increase in reliability of the tube bundle operation, a decrease in noise and

  11. Solar fuels generator

    Science.gov (United States)

    Lewis, Nathan S.; Spurgeon, Joshua M.

    2016-10-25

    The solar fuels generator includes an ionically conductive separator between a gaseous first phase and a second phase. A photoanode uses one or more components of the first phase to generate cations during operation of the solar fuels generator. A cation conduit is positioned provides a pathway along which the cations travel from the photoanode to the separator. The separator conducts the cations. A second solid cation conduit conducts the cations from the separator to a photocathode.

  12. Further Development, Support and Enhancement of CONDUIT

    Science.gov (United States)

    Veronica, Moldoveanu; Levine, William S.

    1999-01-01

    From the first airplanes steered by handles, wheels, and pedals to today's advanced aircraft, there has been a century of revolutionary inventions, all of them contributing to flight quality. The stability and controllability of aircraft as they appear to a pilot are called flying or handling qualities. Many years after the first airplanes flew, flying qualities were identified and ranked from desirable to unsatisfactory. Later on engineers developed design methods to satisfy these practical criteria. CONDUIT, which stands for Control Designer's Unified Interface, is a modern software package that provides a methodology for optimization of flight control systems in order to improve the flying qualities. CONDUIT is dependent on an the optimization engine called CONSOL-OPTCAD (C-O). C-O performs multicriterion parametric optimization. C-O was successfully tested on a variety of control problems. The optimization-based computational system, C-O, requires a particular control system description as a MATLAB file and possesses the ability to modify the vector of design parameters in an attempt to satisfy performance objectives and constraints specified by the designer, in a C-type file. After the first optimization attempts on the UH-60A control system, an early interface system, named GIFCORCODE (Graphical Interface for CONSOL-OPTCAD for Rotorcraft Controller Design) was created.

  13. Effects of streptozotocin-induced diabetes on the pharmacology of rat conduit and resistance intrapulmonary arteries

    Directory of Open Access Journals (Sweden)

    Howarth Frank C

    2009-01-01

    Full Text Available Abstract Background Poor control of blood glucose in diabetes is known to promote vascular dysfunction and hypertension. Diabetes was recently shown to be linked to an increased prevalence of pulmonary hypertension. The aim of this study was to determine how the pharmacological reactivity of intrapulmonary arteries is altered in a rat model of diabetes. Methods Diabetes was induced in rats by the β-cell toxin, streptozotocin (STZ, 60 mg/kg, and isolated conduit and resistance intrapulmonary arteries studied 3–4 months later. Isometric tension responses to the vasoconstrictors phenylephrine, serotonin and PGF2α, and the vasodilators carbachol and glyceryl trinitrate, were compared in STZ-treated rats and age-matched controls. Results STZ-induced diabetes significantly blunted the maximum response of conduit, but not resistance pulmonary arteries to phenylephrine and serotonin, without a change in pEC50. Agonist responses were differentially reduced, with serotonin (46% smaller affected more than phenylephrine (32% smaller and responses to PGF2α unaltered. Vasoconstriction caused by K+-induced depolarisation remained normal in diabetic rats. Endothelium-dependent dilation to carbachol and endothelium-independent dilation to glyceryl trinitrate were also unaffected. Conclusion The small resistance pulmonary arteries are relatively resistant to STZ-induced diabetes. The impaired constrictor responsiveness of conduit vessels was agonist dependent, suggesting possible loss of receptor expression or function. The observed effects cannot account for pulmonary hypertension in diabetes, rather the impaired reactivity to vasoconstrictors would counteract the development of pulmonary hypertensive disease.

  14. Application of high-tech three-dimensional imaging and computer-generated models in complex facial reconstructions with vascularized bone grafts.

    Science.gov (United States)

    Rose, E H; Norris, M S; Rosen, J M

    1993-02-01

    We present a series of six patients with eight flaps in whom computer-generated models were used for fabrication of vascularized bone grafts in complex facial restorations. Preoperative CT data, digitalized on tape, were converted by the CEMAX (Santa Clara, Calif.) 1500 Integrated Hardware and Software System to a three-dimensional visualization of the bone and soft-tissue deficiencies. These data were transmitted by direct computer link to a CNC milling machine that produced full-size slices "stacked" into a three-dimensional template. The acrylic replica aided selection of appropriate donor sites and intraoperative "carving" of bone transfers. Reconstructions included three zygomas, two maxillae, two mandibles, and one frontal bone. Donor sites were iliac crest, scapula, and outer calvarium. Four were free flaps and four island pedicle flaps. All healed without infection. Bone resorption was less than 10 percent. One flap was lost to thrombosis. Other complications included a transient facial palsy in one patient and temporary radial palsy from shoulder traction in another. Computer-generated templates for vascularized grafts are expensive and thus are not indicated or necessary in every patient. The advantages, however, are several. Custom models facilitate preoperative planning, with less guesswork of size, contour, and orientation of the graft, which is especially desirable with vascularized grafts, since the position of the pedicle is critical. Anesthesia time is decreased. Grafts can be fitted exactly, without reshaping and "nibbling." Nuances of depth and tapering are directly carved into the bone. By merging high-tech imaging and microsurgery, the best chance of optimal results can be achieved.

  15. Water Flow in Karst Aquifer Considering Dynamically Variable Saturation Conduit

    Science.gov (United States)

    Tan, Chaoqun; Hu, Bill X.

    2017-04-01

    The karst system is generally conceptualized as dual-porosity system, which is characterized by low conductivity and high storage continuum matrix and high conductivity and quick flow conduit networks. And so far, a common numerical model for simulating flow in karst aquifer is MODFLOW2005-CFP, which is released by USGS in 2008. However, the steady-state approach for conduit flow in CFP is physically impractical when simulating very dynamic hydraulics with variable saturation conduit. So, we adopt the method proposed by Reimann et al. (2011) to improve current model, in which Saint-Venant equations are used to model the flow in conduit. Considering the actual background that the conduit is very big and varies along flow path and the Dirichlet boundary varies with rainfall in our study area in Southwest China, we further investigate the influence of conduit diameter and outflow boundary on numerical model. And we also analyze the hydraulic process in multi-precipitation events. We find that the numerical model here corresponds well with CFP for saturated conduit, and it could depict the interaction between matrix and conduit during very dynamic hydraulics pretty well compare with CFP.

  16. Preclinical evaluations of acellular biological conduits for peripheral nerve regeneration

    Directory of Open Access Journals (Sweden)

    I-Chien Liao

    2013-01-01

    Full Text Available Various types of natural biological conduits have been investigated as alternatives to the current surgical standard approach for peripheral nerve injuries. Autologous nerve graft, the current gold standard for peripheral nerve damage, is limited by clinical challenges such as donor-site morbidity and limited availability. The purpose of this study was to evaluate the efficacy of using acellular xenographic conduits (nerve, artery, and dermis for the repair of a 1.2 cm critical size defect of peripheral nerve in a rodent model. Four months post surgery, the animal group receiving acellular artery as a nerve conduit showed excellent physiological outcome in terms of the prevention of muscle atrophy and foot ulcer. Histological assessment of the bridged site revealed excellent axon regeneration, as opposed to the nonrepaired control group or the group receiving dermal conduit. Finally, the study evaluated the potential improvement via the addition of undifferentiated mesenchymal stem cells into the artery conduit during the bridging procedure. The mesenchymal stem cell–dosed artery conduit group resulted in significantly higher concentration of regenerated axons over artery conduit alone, and exhibited accelerated muscle atrophy rescue. Our results demonstrated that xenographic artery conduits promoted excellent axonal regeneration with highly promising clinical relevance.

  17. Impact of arachidonic versus eicosapentaenoic acid on exotonin-induced lung vascular leakage: relation to 4-series versus 5-series leukotriene generation.

    Science.gov (United States)

    Grimminger, F; Wahn, H; Mayer, K; Kiss, L; Walmrath, D; Seeger, W

    1997-02-01

    Escherichia coli hemolysin (HlyA) is a proteinaceous pore-forming exotoxin that is implicated as a significant pathogenicity factor in extraintestinal E. coli infections including sepsis. In perfused rabbit lungs, subcytolytic concentrations of the toxin evoke thromboxane-mediated vasoconstriction and prostanoid-independent protracted vascular permeability increase (11). In the present study, the influence of submicromolar concentrations of free arachidonic acid (AA) and eicosapentaenoic acid (EPA) on the HlyA-induced leakage response was investigated. HlyA at concentration from 0.02 to 0.06 hemolytic units/ml provoked a dose-dependent, severalfold increase in the capillary filtration coefficient (Kfc), accompanied by the release of leukotriene(LT)B4, LTC4, and LTE4 into the recirculating buffer fluid. Simultaneous application of 100 nmol/L AA markedly augmented the HlyA-elicited leakage response, concomitant with an amplification of LTB4 release and a change in the kinetics of cysteinyl-LT generation. In contrast, 50 to 200 nmol/L EPA suppressed in a dose-dependent manner the HlyA-induced increase in Kfc values. This was accompanied by a blockage of 4-series LT generation and a dose-dependent appearance of LTB5, LTC5, and LTE5. In addition, EPA fully antagonized the AA-induced amplification of the HlyA-provoked Kfc increase, again accompanied by a shift from 4-series to 5-series LT generation. We conclude that the vascular leakage provoked by HlyA in rabbit lungs is differentially influenced by free AA versus free EPA, related to the generation of 4- versus 5-series leukotrienes. The composition of lipid emulsions used for parenteral nutrition may thus influence inflammatory capillary leakage.

  18. Effects of unidirectional permeability in asymmetric poly(DL-lactic acid-co-glycolic acid) conduits on peripheral nerve regeneration: an in vitro and in vivo study.

    Science.gov (United States)

    Chang, Chen-Jung; Hsu, Shan-Hui; Yen, Hung-Jen; Chang, Han; Hsu, Shih-Kuang

    2007-10-01

    The high outflow permeability of the nerve conduit used to emit the drained waste generated from the traumatized host nerve stump is critical in peripheral nerve regeneration. Our earlier studies have established that asymmetric conduits fulfill the basic requirements for use as nerve guide conduits. In this study, the inflow characteristics of optimal nerve conduits were further examined using in vivo and in vitro trials. Various asymmetric poly(DL-lactic acid-co-glycolic acid) (PLGA) conduits were controlled by modifying precipitation baths using 0, 20, and 95% isopropyl alcohol, with high-porosity (permeability), medium-porosity (high outflow and low inflow), and low-porosity (permeability), respectively. In the in vitro trial, the Schwann cells and fibroblasts were seeded on either side of the asymmetric PLGA films in a newly designed coculture system that simulated the repaired nerve conduit environment. The results of the directional permeable films indicated the statistically significant proliferation of Schwann cells and the inhibition of the division of fibroblasts in lactate dehydrogenase release and inhibition of 3-(4,5-dimethylthiazol-2-yl)2,5-diphenyl-tetrazolium bromide (MTT) reduction, compared with the other films. In the in vivo trial, the PLGA conduits seeded with Schwann cells were implanted into 10 mm right sciatic nerve defects in rats. After 6 weeks, implanted conduits were harvested. Histological examination verified that directional permeable conduits had markedly more A-type and B-type myelin fibers in the midconduit and distal nerve. In this work, the directional transport characteristics were established as an extremely important factor to the design and development of optimal nerve guide conduits in peripheral nerve regeneration.

  19. Using Polymeric Scaffolds for Vascular Tissue Engineering

    Directory of Open Access Journals (Sweden)

    Alida Abruzzo

    2014-01-01

    Full Text Available With the high occurrence of cardiovascular disease and increasing numbers of patients requiring vascular access, there is a significant need for small-diameter (<6 mm inner diameter vascular graft that can provide long-term patency. Despite the technological improvements, restenosis and graft thrombosis continue to hamper the success of the implants. Vascular tissue engineering is a new field that has undergone enormous growth over the last decade and has proposed valid solutions for blood vessels repair. The goal of vascular tissue engineering is to produce neovessels and neoorgan tissue from autologous cells using a biodegradable polymer as a scaffold. The most important advantage of tissue-engineered implants is that these tissues can grow, remodel, rebuild, and respond to injury. This review describes the development of polymeric materials over the years and current tissue engineering strategies for the improvement of vascular conduits.

  20. Spotlight on CERN : Le code de conduite

    CERN Multimedia

    CERN Video Productions

    2010-01-01

    Cette année 2010, le démarrage du LHC a été le témoignage de la réussite de la collaboration scientifique au CERN, rapprochant les personnes, hommes et femmes, tous ensemble pour la plus grande des réalisations. Cette collaboration nécessite une ouverture sur la diversité basée sur des valeurs solides. Pour s’assurer que l'Organisation continue sur la voie du succès, un consensus a été atteint sur des valeurs caractérisant le CERN et celles-ci ont été regroupées dans un Code de conduite, décrivant la norme de base du comportement que nous pouvons tous espérer de nous-mêmes et de nos collègues sur notre lieu de travail. Entrevues avec Rolf Heuer, Directeur Général du CERN, Anne-Sylvie Catherin, Chef du Département des Ressources Humaines, et Vincent Vuillemin, Ombuds au CERN.

  1. Biological conduit small gap sleeve bridging method for peripheral nerve injury: regeneration law of nerve fibers in the conduit

    Directory of Open Access Journals (Sweden)

    Pei-xun Zhang

    2015-01-01

    Full Text Available The clinical effects of 2-mm small gap sleeve bridging of the biological conduit to repair peripheral nerve injury are better than in the traditional epineurium suture, so it is possible to replace the epineurium suture in the treatment of peripheral nerve injury. This study sought to identify the regeneration law of nerve fibers in the biological conduit. A nerve regeneration chamber was constructed in models of sciatic nerve injury using 2-mm small gap sleeve bridging of a biodegradable biological conduit. The results showed that the biological conduit had good histocompatibility. Tissue and cell apoptosis in the conduit apparently lessened, and regenerating nerve fibers were common. The degeneration regeneration law of Schwann cells and axons in the conduit was quite different from that in traditional epineurium suture. During the prime period for nerve fiber regeneration (2-8 weeks, the number of Schwann cells and nerve fibers was higher in both proximal and distal ends, and the effects of the small gap sleeve bridging method were better than those of the traditional epineurium suture. The above results provide an objective and reliable theoretical basis for the clinical application of the biological conduit small gap sleeve bridging method to repair peripheral nerve injury.

  2. Simvastatin inhibits homocysteine-induced CRP generation via interfering with the ROS-p38/ERK1/2 signal pathway in rat vascular smooth muscle cells.

    Science.gov (United States)

    Pang, Xiaoming; Si, Jigang; Xu, Shouzhu; Li, Yuxia; Liu, Juntian

    2017-01-01

    Inflammation plays a pivotal role throughout the formation and progression of atherosclerosis. As the most representative inflammatory marker, C-reactive protein (CRP) directly participates in the initiation and development of atherosclerosis. The elevated homocysteine (Hcy) level in plasma is an independent risk factor for atherosclerosis. We previously reported that Hcy produces a pro-inflammatory effect by stimulating CRP expression in vascular smooth muscle cells (VSMCs). The present study observed the effect of simvastatin on Hcy-induced CRP expression in VSMCs and the molecular mechanisms. The in vitro experiments revealed that pretreatment of VSMCs with simvastatin decreased Hcy-induced mRNA and protein expression of CRP in a concentration-dependent fashion. The in vivo results showed that simvastatin not only inhibited CRP expression in the vessel walls in mRNA and protein levels, but also reduced the circulating CRP level in hyperhomocysteinemic rats. Further experiments displayed that simvastatin reduced Hcy-induced reactive oxygen species (ROS) generation, ameliorated Hcy-activated phosphorylations of ERK1/2 and p38, and antagonized Hcy-downregulated peroxisome proliferator-activated receptor gamma expression in VSMCs. These data demonstrate that simvastatin is able to inhibit Hcy-induced CRP generation in VSMCs so to relieve the vascular inflammatory response via interfering with the ROS-MAPK signal pathway. The present results provide new evidence for understanding of the potential anti-inflammatory and anti-atherosclerotic effects of simvastatin. As the high level of Hcy in plasma is related to atherosclerosis formation and mediates cardiovascular risk, our findings emphasize the importance and necessity of therapy with statins for hyperhomocysteinemia in atherosclerosis. Copyright © 2016 Elsevier Inc. All rights reserved.

  3. Evaluation of venous and arterial conduit patency by 16-slice spiral computed tomography.

    Science.gov (United States)

    Martuscelli, E; Romagnoli, A; D'Eliseo, A; Tomassini, M; Razzini, C; Sperandio, M; Simonetti, G; Romeo, F; Mehta, J L

    2004-11-16

    Computed tomography has been shown to be useful in the evaluation of aortocoronary bypass grafts (CABG). This is the first prospective study to evaluate the accuracy of a new-generation scanner in the detection of patency and significant stenoses (>50% decrease in diameter) of venous and arterial grafts in patients with previous CABG. In 96 patients (80 males, mean age 62 years) with previous CABG, a multislice computed tomography (MSCT) scan was performed (collimation 16x0.625 mm). Patients with atrial fibrillation, renal failure, severe respiratory disease, severe heart failure, heart rate >70 bpm despite therapy, or unstable angina were excluded. A total of 285 conduits implanted on the native coronary arteries at the time of CABG were evaluated. MSCT data were analyzed by 2 independent radiologists and compared with the results of conventional angiography. Three patients were excluded from analysis. All conduits were judged evaluable in 84 patients. Among these patients, MSCT correctly diagnosed 54 occluded grafts and 4 significant stenoses on the body of the grafts. Of the 17 significant anastomotic lesions, MSCT correctly diagnosed 15. For these 84 patients, diagnostic accuracy was 99%, sensitivity was 97%, and specificity was 100%. When all 93 patients were considered, the sensitivity of MSCT in diagnosing significant stenoses was 96%. MSCT with the new-generation scanner allows for accurate assessment of venous and arterial conduits in patients with previous CABG with a high degree of sensitivity and specificity. Exclusion criteria and radiation exposure remain limitations of the method.

  4. Pediatric Vascular Surgery Review with a 30-Year-Experience in a Tertiary Referral Center

    Science.gov (United States)

    Min, Seung-Kee; Cho, Sungsin; Kim, Hyun-Young; Kim, Sang Joon

    2017-01-01

    Pediatric vascular disease is rare, and remains a big challenge to vascular surgeons. In contrast to adults, surgery for pediatric vascular disease is complicated by issues related to small size, future growth, and availability of suitable vascular conduit. During the last 30 years, 131 major vascular operations were performed in a tertiary referral center, Seoul National University Hospital, including aortoiliac aneurysm, acute or chronic arterial occlusion, renovascular hypertension, portal venous hypertension, trauma, tumor invasion to major abdominal vessels, and others. Herein we review on the important pediatric vascular diseases and share our clinical experiences on these rare diseases. PMID:28690995

  5. Pseudomembranous colitis associated with changes in an ileal conduit.

    Science.gov (United States)

    Shortland, J R; Spencer, R C; Williams, J L

    1983-01-01

    A case of antibiotic associated pseudomembranous colitis following total cystectomy is reported, in which there was involvement of the ileal conduit. The small bowel remaining in situ was uninvolved. Bacteriological studies revealed Clostridium difficile and the toxin in both colon and ileal conduit. Relevant publications concerning pathogenesis are discussed, in relation to the unusual site described in this case. Epidemiological evidence is reviewed which suggests that isolation of patients with pseudomembranous colitis is a logical course of action. Images PMID:6619315

  6. Endogenously generated plasmin at the vascular wall injury site amplifies lysine binding site-dependent plasminogen accumulation in microthrombi.

    Directory of Open Access Journals (Sweden)

    Tomasz Brzoska

    Full Text Available The fibrinolytic system plays a pivotal role in the regulation of hemostasis; however, it remains unclear how and when the system is triggered to induce thrombolysis. Using intra-vital confocal fluorescence microscopy, we investigated the process of plasminogen binding to laser-induced platelet-rich microthrombi generated in the mesenteric vein of transgenic mice expressing green fluorescent protein (GFP. The accumulation of GFP-expressing platelets as well as exogenously infused Alexa Fluor 568-labeled Glu-plasminogen (Glu-plg on the injured vessel wall was assessed by measuring the increase in the corresponding fluorescence intensities. Glu-plg accumulated in a time-dependent manner in the center of the microthrombus, where phosphatidylserine is exposed on platelet surfaces and fibrin formation takes place. The rates of binding of Glu-plg in the presence of ε-aminocaproic acid and carboxypeptidase B, as well as the rates of binding of mini-plasminogen lacking kringle domains 1-4 and lysine binding sites, were significantly lower than that of Glu-plg alone, suggesting that the binding was dependent on lysine binding sites. Furthermore, aprotinin significantly suppressed the accumulation of Glu-plg, suggesting that endogenously generated plasmin activity is a prerequisite for the accumulation. In spite of the endogenous generation of plasmin and accumulation of Glu-plg in the center of microthrombi, the microthrombi did not change in size during the 2-hour observation period. When human tissue plasminogen activator was administered intravenously, Glu-plg further accumulated and the microthrombi were lysed. Glu-plg appeared to accumulate in the center of microthrombi in the early phase of microthrombus formation, and plasmin activity and lysine binding sites were required for this accumulation.

  7. Molecular Control of Vascular Tube Morphogenesis and Stabilization: Regulation by Extracellular Matrix, Matrix Metalloproteinases, and Endothelial Cell-Pericyte Interactions

    Science.gov (United States)

    Davis, George E.; Stratman, Amber N.; Sacharidou, Anastasia

    Recent studies have revealed a critical role for both extracellular matrices and matrix metalloproteinases in the molecular control of vascular morphogenesis and stabilization in three-dimensional (3D) tissue environments. Key interactions involve endothelial cells (ECs) and pericytes, which coassemble to affect vessel formation, remodeling, and stabilization events during development and postnatal life. EC-pericyte interactions control extracellular matrix remodeling events including vascular basement membrane matrix assembly, a necessary step for endothelial tube maturation and stabilization. ECs form tube networks in 3D extracellular matrices in a manner dependent on integrins, membrane-type metalloproteinases, and the Rho GTPases, Cdc42 and Rac1. Recent work has defined an EC lumen signaling complex of proteins composed of these proteins that controls 3D matrix-specific signaling events required for these processes. The EC tube formation process results in the creation of a network of proteolytically generated vascular guidance tunnels. These tunnels are physical matrix spaces that regulate vascular tube remodeling and represent matrix conduits into which pericytes are recruited to allow dynamic cell-cell interactions with ECs. These dynamic EC-pericyte interactions induce vascular basement membrane matrix deposition, leading to vessel maturation and stabilization.

  8. Heterogeneity in conduit artery function in humans: impact of arterial size.

    Science.gov (United States)

    Thijssen, Dick H J; Dawson, Ellen A; Black, Mark A; Hopman, Maria T E; Cable, N Timothy; Green, Daniel J

    2008-11-01

    To determine whether conduit artery size affects functional responses, we compared the magnitude, time course, and eliciting shear rate stimulus for flow-mediated dilation (FMD) in healthy men (n = 20; 31 +/- 7 yr). Upper limb (brachial and radial) and lower limb (common and superficial femoral) FMD responses were simultaneously assessed, whereas popliteal responses were measured in the same subjects during a separate visit. Glyceryl trinitrate (GTN)-mediated responses were similarly examined. Edge detection and wall tracking of high-resolution B-mode arterial ultrasound images, combined with synchronized Doppler waveform envelope analysis, were used to calculate conduit artery diameter, blood flow, and shear rate continuously across the cardiac cycle. Baseline artery size correlated inversely with the FMD response (r = -0.57, P < 0.001). Within-artery comparisons revealed a significant inverse correlation between artery size and FMD% for the radial (r = -0.66, P = 0.001), brachial (r = -0.55, P = 0.01), and popliteal artery (r = -0.48, P = 0.03), but not for the superficial and common femoral artery. Normalization of FMD responses for differences in eliciting shear rate did not abolish the between-artery relationship for artery function and size (r = -0.48, P < 0.001), suggesting that differences between artery function responses were not entirely due to size-related differences in shear rate. This was reinforced by a significant between-artery correlation for GTN responses and baseline artery size (r = -0.74, P < 0.001). In summary, systematic differences exist in vascular function responses of conduit arteries that differ in size. This raises the possibility that differences in artery size within or between individuals may influence functional responses.

  9. Comprehensive Virus Detection Using Next Generation Sequencing in Grapevine Vascular Tissues of Plants Obtained from the Wine Regions of Bohemia and Moravia (Czech Republic)

    Science.gov (United States)

    2016-01-01

    Comprehensive next generation sequencing virus detection was used to detect the whole spectrum of viruses and viroids in selected grapevines from the Czech Republic. The novel NGS approach was based on sequencing libraries of small RNA isolated from grapevine vascular tissues. Eight previously partially-characterized grapevines of diverse varieties were selected and subjected to analysis: Chardonnay, Laurot, Guzal Kara, and rootstock Kober 125AA from the Moravia wine-producing region; plus Müller-Thurgau and Pinot Noir from the Bohemia wine-producing region, both in the Czech Republic. Using next generation sequencing of small RNA, the presence of 8 viruses and 2 viroids were detected in a set of eight grapevines; therefore, confirming the high effectiveness of the technique in plant virology and producing results supporting previous data on multiple infected grapevines in Czech vineyards. Among the pathogens detected, the Grapevine rupestris vein feathering virus and Grapevine yellow speckle viroid 1 were recorded in the Czech Republic for the first time. PMID:27959951

  10. In Vitro Generation of Vascular Wall-Resident Multipotent Stem Cells of Mesenchymal Nature from Murine Induced Pluripotent Stem Cells

    Directory of Open Access Journals (Sweden)

    Jennifer Steens

    2017-04-01

    Full Text Available The vascular wall (VW serves as a niche for mesenchymal stem cells (MSCs. In general, tissue-specific stem cells differentiate mainly to the tissue type from which they derive, indicating that there is a certain code or priming within the cells as determined by the tissue of origin. Here we report the in vitro generation of VW-typical MSCs from induced pluripotent stem cells (iPSCs, based on a VW-MSC-specific gene code. Using a lentiviral vector expressing the so-called Yamanaka factors, we reprogrammed tail dermal fibroblasts from transgenic mice containing the GFP gene integrated into the Nestin-locus (NEST-iPSCs to facilitate lineage tracing after subsequent MSC differentiation. A lentiviral vector expressing a small set of recently identified human VW-MSC-specific HOX genes then induced MSC differentiation. This direct programming approach successfully mediated the generation of VW-typical MSCs with classical MSC characteristics, both in vitro and in vivo.

  11. Comprehensive Virus Detection Using Next Generation Sequencing in Grapevine Vascular Tissues of Plants Obtained from the Wine Regions of Bohemia and Moravia (Czech Republic.

    Directory of Open Access Journals (Sweden)

    Aleš Eichmeier

    Full Text Available Comprehensive next generation sequencing virus detection was used to detect the whole spectrum of viruses and viroids in selected grapevines from the Czech Republic. The novel NGS approach was based on sequencing libraries of small RNA isolated from grapevine vascular tissues. Eight previously partially-characterized grapevines of diverse varieties were selected and subjected to analysis: Chardonnay, Laurot, Guzal Kara, and rootstock Kober 125AA from the Moravia wine-producing region; plus Müller-Thurgau and Pinot Noir from the Bohemia wine-producing region, both in the Czech Republic. Using next generation sequencing of small RNA, the presence of 8 viruses and 2 viroids were detected in a set of eight grapevines; therefore, confirming the high effectiveness of the technique in plant virology and producing results supporting previous data on multiple infected grapevines in Czech vineyards. Among the pathogens detected, the Grapevine rupestris vein feathering virus and Grapevine yellow speckle viroid 1 were recorded in the Czech Republic for the first time.

  12. In Vitro Generation of Vascular Wall-Resident Multipotent Stem Cells of Mesenchymal Nature from Murine Induced Pluripotent Stem Cells.

    Science.gov (United States)

    Steens, Jennifer; Zuk, Melanie; Benchellal, Mohamed; Bornemann, Lea; Teichweyde, Nadine; Hess, Julia; Unger, Kristian; Görgens, André; Klump, Hannes; Klein, Diana

    2017-04-11

    The vascular wall (VW) serves as a niche for mesenchymal stem cells (MSCs). In general, tissue-specific stem cells differentiate mainly to the tissue type from which they derive, indicating that there is a certain code or priming within the cells as determined by the tissue of origin. Here we report the in vitro generation of VW-typical MSCs from induced pluripotent stem cells (iPSCs), based on a VW-MSC-specific gene code. Using a lentiviral vector expressing the so-called Yamanaka factors, we reprogrammed tail dermal fibroblasts from transgenic mice containing the GFP gene integrated into the Nestin-locus (NEST-iPSCs) to facilitate lineage tracing after subsequent MSC differentiation. A lentiviral vector expressing a small set of recently identified human VW-MSC-specific HOX genes then induced MSC differentiation. This direct programming approach successfully mediated the generation of VW-typical MSCs with classical MSC characteristics, both in vitro and in vivo. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

  13. The formation and migration of sand ripples in closed conduits: experiments with turbulent water flows

    CERN Document Server

    Florez, Jorge Eduar Cardona

    2016-01-01

    The transport of solid particles by a fluid flow is frequently found in nature and industry. Some examples are the transport of sand in rivers and hydrocarbon pipelines. When the shear stresses exerted by a fluid flow on a granular bed remain moderate, some grains are set in motion without fluidizing the bed; the moving grains form a layer, known as bed load, that moves while maintaining contact with the fixed part of the bed. Under bed load conditions, the granular bed may become unstable, generating ripples and dunes. Sand ripples are commonly observed in closed conduits and pipes such as in petroleum pipelines, sewer systems, and dredging lines. Although of importance for many scientific domains and industrial applications, the formation of ripples in closed conduits is not well understood, and the problem is still open. This paper presents an experimental study on the formation and migration of sand ripples under a turbulent closed-conduit flow and bed-load conditions. In our experiments, fully-developed ...

  14. Repeated increases in blood flow, independent of exercise, enhance conduit artery vasodilator function in humans.

    Science.gov (United States)

    Naylor, Louise H; Carter, Howard; FitzSimons, Matthew G; Cable, N Timothy; Thijssen, Dick H J; Green, Daniel J

    2011-02-01

    This study aimed to determine the importance of repeated increases in blood flow to conduit artery adaptation, using an exercise-independent repeated episodic stimulus. Recent studies suggest that exercise training improves vasodilator function of conduit arteries via shear stress-mediated mechanisms. However, exercise is a complex stimulus that may induce shear-independent adaptations. Nine healthy men immersed their forearms in water at 42°C for three 30-min sessions/wk across 8 wk. During each session, a pneumatic pressure cuff was inflated around one forearm to unilaterally modulate heating-induced increases in shear. Forearm heating was associated with an increase in brachial artery blood flow (P<0.001) and shear rate (P<0.001) in the uncuffed forearm; this response was attenuated in the cuffed limb (P<0.005). Repeated episodic exposure to bilateral heating induced an increase in endothelium-dependent vasodilation in response to 5-min ischemic (P<0.05) and ischemic handgrip exercise (P<0.005) stimuli in the uncuffed forearm, whereas the 8-wk heating intervention did not influence dilation to either stimulus in the cuffed limb. Endothelium-independent glyceryl trinitrate responses were not altered in either limb. Repeated heating increases blood flow to levels that enhance endothelium-mediated vasodilator function in humans. These findings reinforce the importance of the direct impacts of shear stress on the vascular endothelium in humans.

  15. Geodynamic modeling of the capture and release of a plume conduit by a migrating mid-ocean ridge

    Science.gov (United States)

    Hall, P. S.

    2011-12-01

    plates over the relatively stationary, long-lived conduits of mantle plumes. However, paleomagnetic data from the Hawaii-Emperor Seamount Chain suggests that the Hawaiian hotspot moved rapidly (~40 mm/yr) between 81 - 47 Ma [Tarduno et al., 2003]. Recently, Tarduno et al. [2009] suggested that this period of rapid motion might be the surface expression of a plume conduit returning to a largely vertical orientation after having been captured and tilted as the result of being "run over" by migrating mid-ocean ridge. I report on a series of analog geodynamic experiments designed to characterize the evolution of a plume conduit as a mid-ocean ridge migrates over. Experiments were conducted in a clear acrylic tank (100 cm x 70 cm x 50 cm) filled with commercial grade high-fructose corn syrup. Plate-driven flow is modeled by dragging two sheets of Mylar film (driven by independent DC motors) in opposite directions over the surface of the fluid. Ridge migration is achieved by moving the point at which the mylar sheets diverge using a separate motor drive. Buoyant plume flow is generated using a small electrical heater placed at the bottom of the tank. Plate velocities and ridge migration rate are controlled and plume temperature monitored using LabView software. Experiments are recorded using digital video which is then analyzed using digital image analysis software to track the position and shape of the plume conduit throughout the course of the experiment. The intersection of the plume conduit with the surface of the fluid is taken as an analog for the locus of hotspot volcanism and tracked as a function of time to obtain a hotspot migration rate. Results show that the plume conduit experiences significant tilting immediately following the passage of the migrating ridge.

  16. Robotic Assisted Radical Cystoprostatectomy and Intracorporeal Ileal Conduit Urinary Diversion for a Kidney Transplant Recipient

    Directory of Open Access Journals (Sweden)

    Peter A. Caputo

    Full Text Available ABSTRACT Introduction and Objectives: Robotic assisted radical cystectomy (RARC is an alternative to open radical cystectomy. As experience is gained with the RARC approach the technique is being applied to more complex surgical cases. We describe here our technique for RARC with intracorporeal ileal conduit urinary diversion for a renal transplant recipient. Materials and Methods: The patient is a 60-year old man with high-grade muscle invasive bladder cancer. He has a history of renal failure due to polycystic kidney disease and received a deceased donor renal transplant in 2008. His hospital course at time of transplant was complicated by low-level BK virus viremia. Interestingly his trans-urethral bladder tumor resection specimen at time of bladder cancer diagnosis stained positive for SV40. His native kidneys were anuric so bilateral laparoscopic nephrectomy was performed in a staged fashion 2 weeks prior to RARC. Our surgical technique utilizes 6 trocars, of note a 12-mm assistant trocar is placed 1 cm superior to the pubic symphysis, and this trocar is solely used to pass a laparoscopic stapler to facilitate the excision of the ileal segment and the stapled enteric anastomosis. Surgical steps include: identification of native ureters bilaterally (removed en bloc with the bladder specimen; identification of the transplanted ureter at the right bladder dome; posterior bladder and prostate dissection along Denonvilliers’ fascia; development of the space of Retzius; ligation and transection of the bladder and prostate vascular bundles; apical prostate dissection and transection of urethra; left pelvic lymphadenectomy; ilium resection for creation of the ileal conduit; stapled enteric anastomosis; ureteroileal anastomosis; maturation of the ileal conduit stoma. Results: The surgery had no intraoperative complications. Operative time was 443 minutes (7.4 hours. Estimated blood loss was 250 cc. Length of hospital stay was 5 days. The patient

  17. [Vascular dementia

    NARCIS (Netherlands)

    Leeuw, H.F. de; Gijn, J. van

    2004-01-01

    Vascular dementia is one of the most frequently occurring dementia syndromes. Its prevalence is about 5% among subjects above 85 years of age. Elevated blood pressure and atherosclerosis are the most important risk factors. According to international criteria, vascular dementia usually occurs within

  18. Vascular Gene Expression: A Hypothesis

    Directory of Open Access Journals (Sweden)

    Angélica Concepción eMartínez-Navarro

    2013-07-01

    Full Text Available The phloem is the conduit through which photoassimilates are distributed from autotrophic to heterotrophic tissues and is involved in the distribution of signaling molecules that coordinate plant growth and responses to the environment. Phloem function depends on the coordinate expression of a large array of genes. We have previously identified conserved motifs in upstream regions of the Arabidopsis genes, encoding the homologs of pumpkin phloem sap mRNAs, displaying expression in vascular tissues. This tissue-specific expression in Arabidopsis is predicted by the overrepresentation of GA/CT-rich motifs in gene promoters. In this work we have searched for common motifs in upstream regions of the homologous genes from plants considered to possess a primitive vascular tissue (a lycophyte, as well as from others that lack a true vascular tissue (a bryophyte, and finally from chlorophytes. Both lycophyte and bryophyte display motifs similar to those found in Arabidopsis with a significantly low E-value, while the chlorophytes showed either a different conserved motif or no conserved motif at all. These results suggest that these same genes are expressed coordinately in non- vascular plants; this coordinate expression may have been one of the prerequisites for the development of conducting tissues in plants. We have also analyzed the phylogeny of conserved proteins that may be involved in phloem function and development. The presence of CmPP16, APL, FT and YDA in chlorophytes suggests the recruitment of ancient regulatory networks for the development of the vascular tissue during evolution while OPS is a novel protein specific to vascular plants.

  19. Dual-Component Gelatinous Peptide/Reactive Oligomer Formulations as Conduit Material and Luminal Filler for Peripheral Nerve Regeneration.

    Science.gov (United States)

    Kohn-Polster, Caroline; Bhatnagar, Divya; Woloszyn, Derek J; Richtmyer, Matthew; Starke, Annett; Springwald, Alexandra H; Franz, Sandra; Schulz-Siegmund, Michaela; Kaplan, Hilton M; Kohn, Joachim; Hacker, Michael C

    2017-05-21

    Toward the next generation of nerve guidance conduits (NGCs), novel biomaterials and functionalization concepts are required to address clinical demands in peripheral nerve regeneration (PNR). As a biological polymer with bioactive motifs, gelatinous peptides are promising building blocks. In combination with an anhydride-containing oligomer, a dual-component hydrogel system (cGEL) was established. First, hollow cGEL tubes were fabricated by a continuous dosing and templating process. Conduits were characterized concerning their mechanical strength, in vitro and in vivo degradation and biocompatibility. Second, cGEL was reformulated as injectable shear thinning filler for established NGCs, here tyrosine-derived polycarbonate-based braided conduits. Thereby, the formulation contained the small molecule LM11A-31. The biofunctionalized cGEL filler was assessed regarding building block integration, mechanical properties, in vitro cytotoxicity, and growth permissive effects on human adipose tissue-derived stem cells. A positive in vitro evaluation motivated further application of the filler material in a sciatic nerve defect. Compared to the empty conduit and pristine cGEL, the functionalization performed superior, though the autologous nerve graft remains the gold standard. In conclusion, LM11A-31 functionalized cGEL filler with extracellular matrix (ECM)-like characteristics and specific biochemical cues holds great potential to support PNR.

  20. Dual-Component Gelatinous Peptide/Reactive Oligomer Formulations as Conduit Material and Luminal Filler for Peripheral Nerve Regeneration

    Directory of Open Access Journals (Sweden)

    Caroline Kohn-Polster

    2017-05-01

    Full Text Available Toward the next generation of nerve guidance conduits (NGCs, novel biomaterials and functionalization concepts are required to address clinical demands in peripheral nerve regeneration (PNR. As a biological polymer with bioactive motifs, gelatinous peptides are promising building blocks. In combination with an anhydride-containing oligomer, a dual-component hydrogel system (cGEL was established. First, hollow cGEL tubes were fabricated by a continuous dosing and templating process. Conduits were characterized concerning their mechanical strength, in vitro and in vivo degradation and biocompatibility. Second, cGEL was reformulated as injectable shear thinning filler for established NGCs, here tyrosine-derived polycarbonate-based braided conduits. Thereby, the formulation contained the small molecule LM11A-31. The biofunctionalized cGEL filler was assessed regarding building block integration, mechanical properties, in vitro cytotoxicity, and growth permissive effects on human adipose tissue-derived stem cells. A positive in vitro evaluation motivated further application of the filler material in a sciatic nerve defect. Compared to the empty conduit and pristine cGEL, the functionalization performed superior, though the autologous nerve graft remains the gold standard. In conclusion, LM11A-31 functionalized cGEL filler with extracellular matrix (ECM-like characteristics and specific biochemical cues holds great potential to support PNR.

  1. Vascular ring

    DEFF Research Database (Denmark)

    Schmidt, Anne Mette S; Larsen, Signe H; Hjortdal, Vibeke E

    2018-01-01

    BACKGROUND: Vascular ring is a rare cause of recurrent respiratory infections, dysphagia and stridor. Surgical repair is considered safe but the long-term outcomes are unclear. The purpose of this study was to investigate the mortality and morbidity following vascular ring surgery in a single...... age of 1.4 years (range 0.008-64 years) were operated for vascular ring. Median follow-up was 6.8 years (range 2.4-34 years). Presenting symptoms were stridor (52%), dysphagia or vomiting (52%) and recurrent respiratory infections (48%). There were no early or late deaths. Three months postoperatively...

  2. Repairing nerve gaps by vein conduits filled with lipoaspirate-derived entire adipose tissue hinders nerve regeneration.

    Science.gov (United States)

    Papalia, Igor; Raimondo, Stefania; Ronchi, Giulia; Magaudda, Ludovico; Giacobini-Robecchi, Maria G; Geuna, Stefano

    2013-05-01

    In spite of great recent advancements, the definition of the optimal strategy for bridging a nerve defect, especially across long gaps, still remains an open issue since the amount of autologous nerve graft material is limited while the outcome after alternative tubulization techniques is often unsatisfactory. The aim of this study was to investigate a new tubulization technique based on the employment of vein conduits filled with whole subcutaneous adipose tissue obtained by lipoaspiration. In adult rats, a 1cm-long defect of the left median nerve was repaired by adipose tissue-vein-combined conduits and compared with fresh skeletal muscle tissue-vein-combined conduits and autologous nerve grafts made by the excised nerve segment rotated by 180°. Throughout the postoperative period, functional recovery was assessed using the grasping test. Regenerated nerve samples were withdrawn at postoperative month-6 and processed for light and electron microscopy and stereology of regenerated nerve fibers. Results showed that functional recovery was significantly slower in the adipose tissue-enriched group in comparison to both control groups. Light and electron microscopy showed that a large amount of adipose tissue was still present inside the vein conduits at postoperative month-6. Stereology showed that all quantitative morphological predictors analyzed performed significantly worse in the adipose tissue-enriched group in comparison to the two control groups. On the basis of this experimental study in the rat, the use of whole adipose tissue for tissue engineering of peripheral nerves should be discouraged. Pre-treatment of adipose tissue aimed at isolating stromal vascular fraction and/or adipose derived stem/precursor cells should be considered a fundamental requisite for nerve repair. Copyright © 2012 Elsevier GmbH. All rights reserved.

  3. Vascular anomalies

    Directory of Open Access Journals (Sweden)

    Murthy Jyotsna

    2005-01-01

    Full Text Available Management of vascular anomalies is an emerging multidisciplinary, super-specialisation field involving several surgical, medical and radiological specialties. Over the years, development in this field has been limited because of complex nomenclature and lack of consensus on the best practice for treatment of some of the more complex vascular anomalies. It was only in 1996 that the International Society of the Study of Vascular Anomalies defined nomenclature for the anomalies and gave clear guidelines on management, allowing for improved clinical practices. As in all fields of clinical medicine, the correct diagnosis of the vascular anomalies is essential to choose the appropriate treatment. This paper gives clear guidelines for diagnosis, understanding of the anomalies and discusses their management.

  4. Antioxidants and vascular health.

    Science.gov (United States)

    Bielli, Alessandra; Scioli, Maria Giovanna; Mazzaglia, Donatella; Doldo, Elena; Orlandi, Augusto

    2015-12-15

    Oxygen free radicals and other reactive oxygen species (ROS) are common products of normal aerobic cellular metabolism, but high levels of ROS lead to oxidative stress and cellular damage. Increased production of ROS favors vascular dysfunction, inducing altered vascular permeability and inflammation, accompanied by the loss of vascular modulatory function, the imbalance between vasorelaxation and vasoconstriction, and the aberrant expression of inflammatory adhesion molecules. Inflammatory stimuli promote oxidative stress generated from the increased activity of mitochondrial nicotinamide adenine dinucleotide phosphate oxidase, particularly of the Nox4 isoform, with the consequent impairment of mitochondrial β-oxidation. Vascular dysfunction due to the increase in Nox4 activity and ROS overproduction leads to the progression of cardiovascular diseases, diabetes, inflammatory bowel disease, and neurological disorders. Considerable research into the development of effective antioxidant therapies using natural derivatives or new synthetic molecules has been conducted. Antioxidants may prevent cellular damage by reducing ROS overproduction or interfering in reactions that involve ROS. Vitamin E and ascorbic acid are well known as natural antioxidants that counteract lipid peroxidative damage by scavenging oxygen-derived free radicals, thus restoring vascular function. Recently, preliminary studies on natural antioxidants such as goji berries, thymus, rosemary, green tea ginseng, and garlic have been conducted for their efficacy in preventing vascular damage. N-acetyl-cysteine and propionyl-L-carnitine are synthetic compounds that regulate ROS production by replacing endogenous antioxidants in both endothelial and smooth muscle cells. In this review, we consider the molecular mechanisms underlying the generation of oxidative stress-induced vascular dysfunction as well as the beneficial effects of antioxidant therapies.

  5. Vascular Dementia

    OpenAIRE

    Maria Alekseyevna Cherdak; O V Uspenskaya

    2015-01-01

    This is the author accepted manuscript. The final version is available from Elsevier via http://dx.doi.org/10.1016/S0140-6736(15)00463-8 Vascular dementia is one of the most common causes of dementia after Alzheimer's disease, causing around 15% of cases. However, unlike Alzheimer's disease, there are no licensed treatments for vascular dementia. Progress in the specialty has been difficult because of uncertainties over disease classification and diagnostic criteria, controversy over the e...

  6. Vascular Vertigo

    Directory of Open Access Journals (Sweden)

    Mazyar Hashemilar

    2017-02-01

    Full Text Available Vertigo is a common complaint in neurology and medicine. The most common causes of vertigo are benign paroxysmal positional vertigo, vestibular neuritis, Meniere’s disease, and vascular disorders. Vertigo of vascular origin is usually limited to migraine, transient ischemic attacks, and ischemic or hemorrhagic stroke. Vascular causes lead to various central or peripheral vestibular syndromes with vertigo. This review provides an overview of epidemiology and clinical syndromes of vascular vertigo. Vertigo is an illusion of movement caused by asymmetrical involvement of the vestibular system by various causes. Migraine is the most frequent vascular disorder that causes vertigo in all age groups. Vertigo may occur in up to 25% of patients with migraine. The lifetime prevalence of migrainous vertigo is almost 1%. Cerebrovascular disorders are estimated to account for 3% to 7% of patients with vertigo. Vestibular paroxysmia has been diagnosed in 1.8% to 4% of cases in various dizziness units. Vasculitic disorders are rare in the general population, but vertigo may be seen in almost up to 50% of patients with different vasculitic syndromes. Conclusions: Migraine, cerebrovascular disorders especially involving the vertebrobasilar territory, cardiocirculatory diseases, neurovascular compression of the eighth nerve, and vasculitis are vascular causes of vertigo syndromes.

  7. Morbidity following Ileal Conduit Urinary Diversion in a Welsh ...

    African Journals Online (AJOL)

    In view of the high complication rate, especially in patients with a long life expectancy and benign conditions, objective guidelines regarding the choice of urinary diversion will help surgeons in decision making, patient selection and counseling. Keywords: Ileal conduit diversion, complications, urinary diversion, morbidity, ...

  8. Numerical study of axonal outgrowth in grooved nerve conduits

    Science.gov (United States)

    Yin, Jun; Coutris, Nicole; Huang, Yong

    2012-10-01

    Nerve conduits with grooved inner texture, working as a topographical guidance cue, have been experimentally proved to play a significant role in axonal alignment. How grooved conduits guide axonal outgrowth is of particular interest for studying nerve regeneration. A viscoelastic model of axonal outgrowth in a conduit with a defined grooved geometry characterized by its width in the circumferential direction and its height in the radial direction is developed in this work. In this model, the axon is considered as an elastic beam and the axonal deformation and motion, including stretching, bending and torsion, are described using a Cosserat rod theory. The friction between axon and substrate is also considered in this model as well as the tip outgrowth. It is found that the directional outgrowth of the axon can be significantly improved by the grooved texture: when the groove width decreases or the groove height increases, the axonal elongation in the longitudinal direction of the conduit can be increased, which is in good agreement with experimental observations. This work is the first numerical model to study the effect of the substrate geometry on axonal outgrowth.

  9. Load on Buried Pressure Conduits with Reference to Selection of ...

    African Journals Online (AJOL)

    The use of asbestos-cement pressure conduits is becoming popular even in developing countries. Asbestos-cement pipe can withstand internal pressure of up to 1.4 MPa and is unaffected by corrosion. Its other virtues are that it is light in weight, could be easily cut and filed, is not easily fractured if properly cradled, and can ...

  10. Living in a physical world X. Pumping fluids through conduits

    Indian Academy of Sciences (India)

    2007-02-01

    Feb 1, 2007 ... Home; Journals; Journal of Biosciences; Volume 32; Issue 2. Living in a physical world X. Pumping fluids through conduits. Steven Vogel. Series Volume 32 Issue 2 March 2007 pp 207-222. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/jbsc/032/02/0207-0222 ...

  11. Injunctions against mere conduit of information protected by copyright

    DEFF Research Database (Denmark)

    Sandfeld Jakobsen, Søren; Petersen, Clement Salung

    2011-01-01

    This paper includes an in-depth analysis of EU law and Scandinavian law on injunctions against internet access providers (IAPs) performing as mere conduit of information protected by copyright. In recent Scandinavian case law, courts have granted preliminary injunctions which have caused IAPs...

  12. Effect of SR manipulation on conduit artery dilation in humans

    NARCIS (Netherlands)

    Carter, H.H.; Dawson, E.A.; Birk, G.K.; Spence, A.L.; Naylor, L.H.; Cable, N.T.; Thijssen, D.H.J.; Green, D.J.

    2013-01-01

    The impact of manipulating shear stress on conduit artery vasodilation has not been comprehensively described in vivo. We hypothesized that manipulation of SR through the brachial and radial arteries would be associated with corresponding changes in diameter. We performed a series of studies

  13. Vascular Access Procedures

    Science.gov (United States)

    ... News Physician Resources Professions Site Index A-Z Vascular Access Procedures A vascular access procedure inserts a flexible, ... the limitations of Vascular Access Procedures? What are Vascular Access Procedures? A vascular access procedure involves the insertion ...

  14. Vascular Access for Hemodialysis

    Science.gov (United States)

    ... Adequacy Eating & Nutrition for Hemodialysis Vascular Access for Hemodialysis What is a vascular access? A vascular access ... Set Up the Vascular Access Well before Starting Hemodialysis Patients should set up a vascular access well ...

  15. What Is Vascular Disease?

    Science.gov (United States)

    ... Policy What Is Vascular Disease? What Is Vascular Disease? Vascular disease is any abnormal condition of the blood ... Privacy Policy × Your ticket for the: What Is Vascular Disease? Title What Is Vascular Disease? USD Close Print

  16. AC loss characteristics of simulated CIC-type conductors having plastic conduit

    Science.gov (United States)

    Kojo, Y.; Sekine, N.; Tada, S.; Yamaguchi, Y.; Obama, J.; Takao, T.; Miyagi, D.; Yamanaka, A.

    2003-10-01

    When alternating current superconducting coils having cable-in-conduit conductors are fabricated, non-metallic conduit materials are necessary to avoid eddy current losses in the conduits. Using two kinds of non-metallic tapes made of glass fiber reinforced plastics (GFRPs) and Dyneema fiber reinforced plastics (DFRPs), we made the conductors with the GFRP conduits and DFRP conduits, and experimentally studied the total losses of the conductors. The measured results showed that the total loss of the conductor with the GFRP conduit was smaller than that with the DFRP conduit at the same value of the void ratio, the transport current, the external magnetic field, and so on. When the void ratios become high, the superconducting bundle cable can easily move in the conduit. Hence the measured total losses increased with the void ratios of the conductors.

  17. AC loss characteristics of simulated CIC-type conductors having plastic conduit

    Energy Technology Data Exchange (ETDEWEB)

    Kojo, Y.; Sekine, N.; Tada, S.; Yamaguchi, Y.; Obama, J.; Takao, T.; Miyagi, D.; Yamanaka, A

    2003-10-15

    When alternating current superconducting coils having cable-in-conduit conductors are fabricated, non-metallic conduit materials are necessary to avoid eddy current losses in the conduits. Using two kinds of non-metallic tapes made of glass fiber reinforced plastics (GFRPs) and Dyneema fiber reinforced plastics (DFRPs), we made the conductors with the GFRP conduits and DFRP conduits, and experimentally studied the total losses of the conductors. The measured results showed that the total loss of the conductor with the GFRP conduit was smaller than that with the DFRP conduit at the same value of the void ratio, the transport current, the external magnetic field, and so on. When the void ratios become high, the superconducting bundle cable can easily move in the conduit. Hence the measured total losses increased with the void ratios of the conductors.

  18. Development of a comprehensive inventory management system for underground fiber optic conduits.

    Science.gov (United States)

    2013-03-01

    Major State Departments of Transportation operate and maintain networks of thousands of miles of conduits, many : carrying fiber optic cables that are vital to State communication systems. These conduits are located alongside or : across highways and...

  19. Spectral Analysis of Surface Waves to Detect Buried Concrete Conduits

    Science.gov (United States)

    Hajiani, P.; Anderson, N.; Rogers, J. D.; Elkrry, A.

    2016-12-01

    The detection of underground cavities is of significant concern to geotechnical engineers working in karst terrain. In spite of the marked progress in nondestructive geophysical methods for detecting shallow underground voids, no unique methodology has emerged that can be applied globally. Various studies have been performed on the use of Rayleigh waves to detect shallow tunnels. In this study, we examined the potential of both Rayleigh and Love waves for detecting subsurface voids. Vertical geophones with Eigen-frequencies of 4.5 Hz, 14 Hz, and 100 Hz were utilized to evaluate Rayleigh waves to resolve near-surface tunnels. Seismic surveys were carried out using horizontal 14 Hz geophones to verify the feasibility of using Love waves to detect shallow tunnels. Two buried conduits of known size and embedment were chosen for the study. One conduit serves as a spillway outfall for an embankment dam, and the other as a low flow outlet for aa flood retention basin. Attenuation analyses of surface waves were performed on all of the data sets to identify locations of the buried concrete conduits. In order to minimize the far-field effects, such as body-wave domination, or low signal-to-noise ratio, it was suggested that we try muting the direct waves, refraction, reflection, air wave, and ambient noise. An amplification of energy on, or in front of the near boundary of the conduits was thereby observed. The muting process greatly reduced the number of false positives. The results of this study not only confirmed previous work, but also displayed the ability of Love waves in detecting the shallow subsurface tunnels or conduits.

  20. Sleep and quality of life in people with ileal conduit.

    Science.gov (United States)

    Cavdar, Ikbal; Temiz, Zeynep; Ozbas, Ayfer; Can, Gulbeyaz; Tarhan, Fatih; Findik, Ummu Yildiz; Kutlu, Fatma Yasemin; Akyuz, Nuray

    2016-12-01

    The aim of this study was to determine the sleep quality and the association between sleep quality and quality of life in people with ileal conduit. A descriptive and cross-sectional design was adopted. The study sample comprised 111 people with ileal conduit operated on in urology clinics in a state hospital between January 2011 and May 2014. Six months after the operation, they were called by telephone to participate in the study. Data for the study were collected using a questionnaire form, the Pittsburgh Sleep Quality Index (PSQI) and the Stoma Quality of Life Scale (SQLS). The mean ± SD total PSQI score of the people with ileal conduit was 10.20 ± 2.95, mean total score of SQLS was 43.63 ± 7.21, mean Work/Social Function domain score was 37.27 ± 5.80 and mean Stoma Function domain score was 50.0 ± 12.56. The total sleep quality had a low degree of negative correlation with total SQLS score, a medium degree of negative correlation with Work/Social Function (r = -0.327, p  .001). People using a night drainage system had higher sleep quality. This study determined that quality of life and sleep deteriorate in people with ileal conduit. The quality of life decreases when the sleep quality is poor, and decreased quality of life affects quality of sleep in people with ileal conduit.

  1. Hemiresective reconstruction of a redundant ileal conduit with severe bilateral ileal conduit-ureteral re fl ux.

    Science.gov (United States)

    Fujimura, Tetsuya; Minowada, Shigeru; Kishi, Hiroichi; Hamasaki, Kimihisa; Saito, Kiyoshi; Kitamura, Tadaichi

    2005-10-01

    A 58-year-old man was referred to our hospital with high fever and anuria. Since undergoing a total pelvic exenteration due to bladder-invasive sigmoid colon cancer, urinary tract infections had frequently occurred. We treated with the construction of a bilateral percutaneous nephrostomy (PCN), and chemotherapy. Although we replaced the PCN with a single J ureteral catheter after an improvement of infection, urinary infection recurred because of an obstruction of the catheter. Urological examinations showed that an ileal conduit-ureteral reflux caused by kinking of the ileal loop was the reason why frequent pyelonephritis occurred. We decided to resect the proximal segment to improve conduit-ureteral reflux for the resistant pyelonephritis. After the surgery, the excretory urogram showed improvement and the urinary retention at the ileal conduit disappeared. Three years after the operation, renal function has been stable without episodes of pyelonephritis. Here we report a case of open repair surgery of an ileal conduit in a patient with severe urinary infection.

  2. Noncovalent Bonding of RGD and YIGSR to an Electrospun Poly(ε-Caprolactone) Conduit through Peptide Self-Assembly to Synergistically Promote Sciatic Nerve Regeneration in Rats.

    Science.gov (United States)

    Zhu, Lei; Wang, Kai; Ma, Teng; Huang, Liangliang; Xia, Bing; Zhu, Shu; Yang, Yafeng; Liu, Zhongyang; Quan, Xin; Luo, Kai; Kong, Deling; Huang, Jinghui; Luo, Zhuojing

    2017-04-01

    The nerve conduit with biofunctionalities can regulate neurite outgrowth, as well as the migration, proliferation, and myelination activity of Schwann cells. In the present study, polycaprolactone (PCL) conduits are coated with Naphthalene-phenylalanine-phenylalanine-glycine-arginine-glycine-aspartic (Nap-FFGRGD) and Naphthalene-phenylalanine-phenylalanine-glycine-cysteine-aspartic-proline-glycine-tyrosine-isoleucine-glycine-serine-arginine (Nap-FFGCDPGYIGSR) by self-assembly. In vitro studies demonstrate that arginine-glycine-aspartic (RGD) and tyrosine-isoleucine-glycine-serine-arginine (YIGSR) are capable of synergistically enhancing the ability of PCL to support the adhesion and proliferation of Schwann cells, as well as increasing neurite outgrowth from dorsal root ganglions explants. This synergistic effect may occur via the activation of both the phosphoinositide 3-kinase/protein kinase B and mitogen-activated protein kinase/extracellular signal-regulated protein kinase pathways. RGD/YIGSR modifications demonstrate beneficial effects across a 15 mm sciatic nerve gap in axonal regeneration and functional recovery. In addition, increased vascularization is observed in the RGD/YIGSR-PCL group, which might contribute to their beneficial effects on nerve regeneration. These findings indicate the potential of the RGD/YIGSR-PCL conduit to promote axonal regeneration and functional recovery, making the RGD/YIGSR-PCL conduit an attractive candidate for the treatment of a critical nerve defect. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Solute Migration from the Aquifer Matrix into a Solution Conduit and the Reverse.

    Science.gov (United States)

    Li, Guangquan; Field, Malcolm S

    2016-09-01

    A solution conduit has a permeable wall allowing for water exchange and solute transfer between the conduit and its surrounding aquifer matrix. In this paper, we use Laplace Transform to solve a one-dimensional equation constructed using the Euler approach to describe advective transport of solute in a conduit, a production-value problem. Both nonuniform cross-section of the conduit and nonuniform seepage at the conduit wall are considered in the solution. Physical analysis using the Lagrangian approach and a lumping method is performed to verify the solution. Two-way transfer between conduit water and matrix water is also investigated by using the solution for the production-value problem as a first-order approximation. The approximate solution agrees well with the exact solution if dimensionless travel time in the conduit is an order of magnitude smaller than unity. Our analytical solution is based on the assumption that the spatial and/or temporal heterogeneity in the wall solute flux is the dominant factor in the spreading of spring-breakthrough curves, and conduit dispersion is only a secondary mechanism. Such an approach can lead to the better understanding of water exchange and solute transfer between conduits and aquifer matrix. Euler and Lagrangian approaches are used to solve transport in conduit. Two-way transfer between conduit and matrix is investigated. The solution is applicable to transport in conduit of persisting solute from matrix. © 2016, National Ground Water Association.

  4. Next-generation sequencing and a novel COL3A1 mutation associated with vascular Ehlers-Danlos syndrome with severe intestinal involvement: a case report.

    Science.gov (United States)

    Cortini, Francesca; Marinelli, Barbara; Seia, Manuela; De Giorgio, Barbara; Pesatori, Angela Cecilia; Montano, Nicola; Bassotti, Alessandra

    2016-10-31

    The vascular type of Ehlers-Danlos syndrome is an autosomal dominant connective tissue disorder caused by a mutation in the COL3A1 gene encoding pro-alpha1 chain of type III collagen. The vascular type of Ehlers-Danlos syndrome causes severe fragility of connective tissues with arterial and intestinal ruptures and complications in surgical and radiological treatments. We present a case of a 38-year-old Italian woman who was diagnosed as having the vascular type of Ehlers-Danlos syndrome. Genetic testing, conducted by Target Enrichment approach (Agilent Technologies), identified a new mutation c.1493G>A, p.G498D in exon 21 of COL3A1 gene (heterozygous state). This mutation disrupts the normal glycine-X-Y repetitions of type III procollagen by converting glycine to aspartic acid. We report a new genetic mutation associated with the vascular type of Ehlers-Danlos syndrome. We also describe clinical and genetic findings that are important to understand the genotype/phenotype correlation in patients with the vascular type of Ehlers-Danlos syndrome.

  5. Vascular dementia.

    Science.gov (United States)

    O'Brien, John T; Thomas, Alan

    2015-10-24

    Vascular dementia is one of the most common causes of dementia after Alzheimer's disease, causing around 15% of cases. However, unlike Alzheimer's disease, there are no licensed treatments for vascular dementia. Progress in the specialty has been difficult because of uncertainties over disease classification and diagnostic criteria, controversy over the exact nature of the relation between cerebrovascular pathology and cognitive impairment, and the paucity of identifiable tractable treatment targets. Although there is an established relation between vascular and degenerative Alzheimer's pathology, the mechanistic link between the two has not yet been identified. This Series paper critiques some of the key areas and controversies, summarises treatment trials so far, and makes suggestions for what progress is needed to advance our understanding of pathogenesis and thus maximise opportunities for the search for new and effective management approaches. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. [Vascular trauma].

    Science.gov (United States)

    Furuya, T; Nobori, M; Tanaka, N

    1999-07-01

    Vascular trauma is essentially acute arterial obstruction, often combined with hemorrhage, fracture, and infection. It can be both life-threatening and limb-threatening and needs an emergency operation. In vascular trauma patient, multiple fracture and organ injury, such as brain, lung, liver, spleen, kidney, or gastrointestinal tract should be evaluated to decide treatment priority. When the pulse distal from the injured site is absent or diminished, vascular trauma is most likely and reconstruction should be accomplished within "the golden time (6-8 hours)". Intimal damage followed by platelet aggregation and thrombus formation will necessitate resection and repair of the site instead of simple thrombectomy. Although autogenous vein is the first choice, artificial graft can be implanted for short segment in non-infected field.

  7. Impact of wall thickness on conduit artery function in humans: is there a "Folkow" effect?

    Science.gov (United States)

    Thijssen, Dick H J; Willems, Laura; van den Munckhof, Inge; Scholten, Ralph; Hopman, Maria T E; Dawson, Ellen A; Atkinson, Greg; Cable, N Timothy; Green, Daniel J

    2011-08-01

    Regional heterogeneity in wall architecture and thickness may be present between conduit arteries in the upper and lower limbs in humans. These differences in wall architecture may, in turn, influence vascular responsiveness. Folkow proposed in the 1950s that heterogeneity in wall-to-lumen ratio (W:L) could contribute to differences in vascular responsiveness, but this hypothesis has never been directly confirmed in vivo. Our first aim was to examine wall thickness and W:L across arteries in the lower (common and superficial femoral) and upper limbs (brachial and radial) of healthy men (n=35) using high resolution ultrasound. In a subgroup (n=20) we examined the relationship between W:L of these arteries, physiological (flow-mediated dilation, FMD) and pharmacological vasodilation (glyceryl trinitrate, GTN). Diameter and wall thickness differed significantly across all arteries (ANOVA P<0.001), with smaller arteries having a relatively larger wall thickness. Moreover, we found a significant correlation between W:L and the FMD-response (r=0.55, P<0.001), which remained significant after correcting for the eliciting shear stress (r=0.47, P<0.001), indicating that W:L/FMD relationship was not primarily related to the impact of diameter on the shear rate stimulus to FMD. W:L also correlated strongly with the GTN-response (r=0.56, P<0.001) across all arteries studied. These results indicate that regional heterogeneity exists in W:L within, but also between, limbs. More importantly, differences in W:L contribute to differences in vascular functional responses, reinforcing the conceptual proposal of Folkow, who suggested that arteries with larger W:L exhibit exaggerated responses to vasoactive stimuli. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  8. Opportunities for Energy Development in Water Conduits: A Report Prepared in Response to Section 7 of the Hydropower Regulatory Efficiency Act of 2013

    Energy Technology Data Exchange (ETDEWEB)

    Sale, Michael J. [BCS, Incorporated, Laurel, MD (United States); Bishop, Norman A. [Knight Piesold, Chicago, IL (United States); Reiser, Sonya L. [Knight Piesold, Chicago, IL (United States); Johnson, Kurt [Telluride Energy LLC, Grand Junction, CO (United States); Bailey, Andrea C. [BCS, Incorporated, Laurel, MD (United States); Frank, Anthony [BCS, Incorporated, Laurel, MD (United States); Smith, Brennan T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Environmental Sciences Division

    2014-09-01

    In Section 7 of the Hydropower Regulatory Efficiency Act (HREA) of 2013 (P.L. 113-23), Congress directed the U.S. Department of Energy (DOE) to prepare an analysis of conduit hydropower opportunities available in the United States and to present case studies that describe the potential energy generation from these types of hydropower projects. Those analyses have been included in a new DOE report to Congress, and this ORNL/TM provides additional technical details supporting that report. Conduit hydropower offers important new ways to enhance renewable energy portfolios in the United States, as well as to increase the energy efficiency of water delivery systems. Conduit hydropower projects are constructed on existing water-conveyance structures, such as irrigation canals or pressurized pipelines that deliver water to municipalities, industry, or agricultural water users. Although water conveyance infrastructures are usually designed for non-power purposes, new renewable energy can often be harvested from them without affecting their original purpose and without the need to construct new dams or diversions. Conduit hydropower differs from more conventional hydropower development in that it is generally not located on natural rivers or waterways and therefore does not involve the types of environmental impacts that are associated with hydropower. The addition of hydropower to existing water conduits can provide valuable new revenue sources from clean, renewable energy. The new energy can be used within the existing water distribution systems to offset other energy demands, or it can be sold into regional transmission systems.

  9. VASCULAR SURGERY

    African Journals Online (AJOL)

    Venous thromboembolism (VTE) is a complex and serious condition encompassing deep vein thrombosis (DVT) and pulmonary embolism (PE), usually in the lower extremities.1,2. Thromboses can result from venous stasis, vascular injury or hypercoagulability, and those involving the deep veins proximal to the knee are ...

  10. HIV-1 evades virus-specific IgG2 and IgA responses by targeting systemic and intestinal B cells via long-range intercellular conduits

    NARCIS (Netherlands)

    Xu, Weifeng; Santini, Paul A.; Sullivan, John S.; He, Bing; Shan, Meimei; Ball, Susan C.; Dyer, Wayne B.; Ketas, Thomas J.; Chadburn, Amy; Cohen-Gould, Leona; Knowles, Daniel M.; Chiu, April; Sanders, Rogier W.; Chen, Kang; Cerutti, Andrea

    2009-01-01

    Contact-dependent communication between immune cells generates protection but also facilitates viral spread. Here we found that macrophages formed long-range actin-propelled conduits in response to negative factor (Nef), a human immunodeficiency virus type 1 (HIV-1) protein with immunosuppressive

  11. Explosive device of conduit using Ti Ni alloy

    Directory of Open Access Journals (Sweden)

    A. Yu. Kolobov

    2014-01-01

    Full Text Available Presently, materials have been developed which are capable at changing temperate to return significant inelastic deformations, exhibit rubber-like elasticity, convert heat into mechanical work, etc. The aggregate of these effects is usually called the shape memory effect.At present a great number of compounds and alloys with a shape memory effect has been known.These are alloys based on titanium nickelide (TiNi, copper-based alloys (Cu-Al, Cu-Sn, Cu-Al-Ni, Cu-Zn-Si, etc., gold and silver (Ag-Cd, Au-Ag-Cd, Au-Cd-Cu, Au-Zn-Cu, etc., manganese (Mn-Cr, Fe-Cu, Mn-Cu-Ni, Mn-Cu-Zr, Mn-Ni, etc., iron (Fe-Mn, Fe-Ni, Fe-Al, etc., and other compounds.The alloys based on titanium nickelide (nitinol are the most widely used.Alloys with shape memory effect find various applications in engineering and medicine, namely connecting devices, actuators, transformable design, multipurpose medical implants, etc.There is a task of breaking fuel conduit during separating the spacecraft from the rocket in space technology.The paper examines the procedure for design calculation of the separating device of conduit with the use of Ti-Ni alloy. This device can be used instead of the pyro-knives.The device contains two semi-rings from Ti-Ni alloy. In the place of break on the conduit an annular radius groove is made.At a temperature of martensite passage the semi-rings undergo deformation and in the strained state are set in the device. With heating to the temperature of the austenitic passage of bushing macro-deformation the energy stored by the nitinol bushing is great enough to break the conduit on the neck.The procedures of design calculation and response time of device are given.

  12. Towards a Tissue-Engineered Contractile Fontan-Conduit: The Fate of Cardiac Myocytes in the Subpulmonary Circulation.

    Directory of Open Access Journals (Sweden)

    Daniel Biermann

    Full Text Available The long-term outcome of patients with single ventricles improved over time, but remains poor compared to other congenital heart lesions with biventricular circulation. Main cause for this unfavourable outcome is the unphysiological hemodynamic of the Fontan circulation, such as subnormal systemic cardiac output and increased systemic-venous pressure. To overcome this limitation, we are developing the concept of a contractile extracardiac Fontan-tunnel. In this study, we evaluated the survival and structural development of a tissue-engineered conduit under in vivo conditions. Engineered heart tissue was generated from ventricular heart cells of neonatal Wistar rats, fibrinogen and thrombin. Engineered heart tissues started beating around day 8 in vitro and remained contractile in vivo throughout the experiment. After culture for 14 days constructs were implanted around the right superior vena cava of Wistar rats (n = 12. Animals were euthanized after 7, 14, 28 and 56 days postoperatively. Hematoxylin and eosin staining showed cardiomyocytes arranged in thick bundles within the engineered heart tissue-conduit. Immunostaining of sarcomeric actin, alpha-actin and connexin 43 revealed a well -developed cardiac myocyte structure. Magnetic resonance imaging (d14, n = 3 revealed no constriction or stenosis of the superior vena cava by the constructs. Engineered heart tissues survive and contract for extended periods after implantation around the superior vena cava of rats. Generation of larger constructs is warranted to evaluate functional benefits of a contractile Fontan-conduit.

  13. Free-boundary models of a meltwater conduit

    KAUST Repository

    Dallaston, Michael C.

    2014-08-01

    © 2014 AIP Publishing LLC. We analyse the cross-sectional evolution of an englacial meltwater conduit that contracts due to inward creep of the surrounding ice and expands due to melting. Making use of theoretical methods from free-boundary problems in Stokes flow and Hele-Shaw squeeze flow we construct an exact solution to the coupled problem of external viscous creep and internal heating, in which we adopt a Newtonian approximation for ice flow and an idealized uniform heat source in the conduit. This problem provides an interesting variant on standard free-boundary problems, coupling different internal and external problems through the kinematic condition at the interface. The boundary in the exact solution takes the form of an ellipse that may contract or expand (depending on the magnitudes of effective pressure and heating rate) around fixed focal points. Linear stability analysis reveals that without the melting this solution is unstable to perturbations in the shape. Melting can stabilize the interface unless the aspect ratio is too small; in that case, instabilities grow largest at the thin ends of the ellipse. The predictions are corroborated with numerical solutions using boundary integral techniques. Finally, a number of extensions to the idealized model are considered, showing that a contracting circular conduit is unstable to all modes of perturbation if melting occurs at a uniform rate around the boundary, or if the ice is modelled as a shear-thinning fluid.

  14. Collagen Type I Conduits for the Regeneration of Nerve Defects

    Directory of Open Access Journals (Sweden)

    Silvan Klein

    2016-03-01

    Full Text Available To date, reliable data to support the general use of biodegradable materials for bridging nerve defects are still scarce. We present the outcome of nerve regeneration following type I collagen conduit nerve repair in patients with large-diameter nerve gaps. Ten patients underwent nerve repair using a type I collagen nerve conduit. Patients were re-examined at a minimal follow-up of 14.0 months and a mean follow-up of 19.9 months. Regeneration of nerve tissue within the conduits was assessed by nerve conduction velocity (NCV, a static two-point discrimination (S2PD test, and as disability of arm shoulder and hand (DASH outcome measure scoring. Quality of life measures including patients’ perceived satisfaction and residual pain were evaluated using a visual analog scale (VAS. No implant-related complications were observed. Seven out of 10 patients reported being free of pain, and the mean VAS was 1.1. The mean DASH score was 17.0. The S2PD was below 6 mm in 40%, between 6 and 10 mm in another 40% and above 10 mm in 20% of the patients. Eight out of 10 patients were satisfied with the procedure and would undergo surgery again. Early treatment correlated with lower DASH score levels. The use of type I collagen in large-diameter gaps in young patients and early treatment presented superior functional outcomes.

  15. Parastomal hernias after radical cystectomy and ileal conduit diversion

    Directory of Open Access Journals (Sweden)

    Timothy F. Donahue

    2016-07-01

    Full Text Available Parastomal hernia, defined as an “incisional hernia related to an abdominal wall stoma”, is a frequent complication after conduit urinary diversion that can negatively impact quality of life and present a clinically significant problem for many patients. Parastomal hernia (PH rates may be as high as 65% and while many patients are asymptomatic, in some series up to 30% of patients require surgical intervention due to pain, leakage, ostomy appliance problems, urinary obstruction, and rarely bowel obstruction or strangulation. Local tissue repair, stoma relocation, and mesh repairs have been performed to correct PH, however, long-term results have been disappointing with recurrence rates of 30%–76% reported after these techniques. Due to high recurrence rates and the potential morbidity of PH repair, efforts have been made to prevent PH development at the time of the initial surgery. Randomized trials of circumstomal prophylactic mesh placement at the time of colostomy and ileostomy stoma formation have shown significant reductions in PH rates with acceptably low complication profiles. We have placed prophylactic mesh at the time of ileal conduit creation in patients at high risk for PH development and found it to be safe and effective in reducing the PH rates over the short-term. In this review, we describe the clinical and radiographic definitions of PH, the clinical impact and risk factors associated with its development, and the use of prophylactic mesh placement for patients undergoing ileal conduit urinary diversion with the intent of reducing PH rates.

  16. Novel drug delivering conduit for peripheral nerve regeneration

    Science.gov (United States)

    Labroo, Pratima; Shea, Jill; Edwards, Kyle; Ho, Scott; Davis, Brett; Sant, Himanshu; Goodwin, Isak; Gale, Bruce; Agarwal, Jay

    2017-12-01

    Objective. This paper describes the design of a novel drug delivery apparatus integrated with a poly lactic-co-glycolic acid (PLGA) based nerve guide conduit for controlled local delivery of nerve growth factor (NGF) and application in peripheral nerve gap injury. Approach. An NGF dosage curve was acquired to determine the minimum in vitro concentration for optimal neurite outgrowth of dorsal root ganglion (DRG) cells; PLGA based drug delivery devices were then designed and tested in vitro and in vivo across 15 mm rat sciatic nerve gap injury model. Main results. The drug delivery nerve guide was able to release NGF for 28 d at concentrations (0.1–10 ng ml‑1) that were shown to enhance DRG neurite growth. Furthermore, the released NGF was bioactive and able to enhance DRG neurite growth. Following these tests, optimized NGF-releasing nerve conduits were implanted across 15 mm sciatic nerve gaps in a rat model, where they demonstrated significant myelination and muscle innervation in vivo as compared to empty nerve conduits (p  injury. Significance. This integrated drug delivering nerve guide simplifies the design process and provides increased versatility for releasing a variety of different growth factors. This innovative device has the potential for broad applicability and allows for easier customization to change the type of drugs and dosage of individual drugs without devising a completely new biomaterial–drug conjugate each time.

  17. Conduit convection driving persistent degassing at basaltic volcanoes

    Science.gov (United States)

    Beckett, F. M.; Burton, M.; Mader, H. M.; Phillips, J. C.; Polacci, M.; Rust, A. C.; Witham, F.

    2014-08-01

    The persistent release of gas at basaltic volcanoes where there is a low magma eruption rate can be driven by an exchange flow of magma in the conduit, in which gas-rich magma ascends, degasses and crystallises and then sinks back down the conduit. The driving force of the flow is provided by the density difference between the buoyant bubble-rich magma at depth and the dense degassed crystallised magma at shallow levels. In this study we attempt to constrain the physical and chemical processes driving an exchange flow of magma at Stromboli, Aeolian Archipelago, Italy. The model uses a simple, cylindrical geometry. We define degassing and crystallisation paths of the ascending and descending magmas, constrained by gas flux and melt inclusion data given in the literature, to produce a three-phase model of ascending and descending magmas driving persistent gas fluxes. We calculate the viscosity of the three-phase magma using end-member rheological models for bubble and crystal suspensions. Combining our modelled magma properties with analogue exchange flow experiments we can relate the regime of magma flow driving persistent degassing to pressure. At pressures ≲ 90 MPa (≲ 3 km) the viscosity ratio is ≲ 100 and the regime is predicted to be side by side flow with both ascending and descending magmas adjacent to a portion of the conduit wall. At pressures ≳ 90 MPa (≳ 3 km) the viscosity ratio between the ascending and descending magma is ≳ 100 and the flow is predicted to be core annular flow, with the ascending vesiculating magma in the inner core and the more crystalline degassed magma flowing down along the conduit wall. By analogy, we hypothesise that degassed magma would flow down along the walls in dike-like plumbing geometries that have been proposed for the deeper Strombolian system. Analogue experiments suggest that exchange flows do not overturn under conditions of maximum volume flux; we use an empirical relationship to characterise the volume

  18. Effects of magma and conduit conditions on transitions between effusive and explosive activity: a numerical modeling approach

    Science.gov (United States)

    Carr, B. B.; De'Michieli Vitturi, M.; Clarke, A. B.; Voight, B.

    2013-12-01

    Transitions between effusive and explosive eruptions, common at silicic volcanoes, can occur between distinct eruptive episodes or can occur as changes between effusive and explosive phases within a single episode. The precise causes of these transitions are difficult to determine due to the multitude of mechanisms and variables that can influence fragmentation thresholds. Numerical modeling of magma ascent within a volcanic conduit allows the influence of key variables to be extensively tested. We study the effect of different variables on the mass eruption rate at the vent using a conservative, 1-D, two-phase, steady-state model that allows for lateral gas loss at shallow depths. Several fragmentation criteria are also tested. We are able to generate a number of regime diagrams for a variety of magma and conduit conditions that constrain transitions from effusive to explosive episodes. We show that a transition to explosive activity can occur without changes in the bulk chemistry, crystal volume fraction, or gas mass fraction of the magma. Eruptive style can be controlled by the pressure gradient within the conduit caused by either overpressure in the chamber or varying lava dome size at the vent. Specific results are sensitive to both magma temperature and conduit geometry. It is important that these variables are well constrained when applying this model to different volcanic systems. We apply our model to the recent activity at Merapi Volcano in Indonesia. We constrain model input and output parameters using current petrologic, seismic, and geodetic studies of the Merapi system, and vary critical parameters over reasonable ranges as documented in the literature. Our model is able to reproduce eruption rates observed during both the 2006 effusive and 2010 explosive/effusive eruptions. Our modeling suggests that a combination of chamber overpressure, increased volatile content, and decreased crystal content due to the voluminous injection of new magma into the

  19. Manufacture of multimicrotubule chitosan nerve conduits with novel molds and characterization in vitro.

    Science.gov (United States)

    Ao, Qiang; Wang, Aijun; Cao, Wenling; Zhang, Ling; Kong, Lijun; He, Qing; Gong, Yandao; Zhang, Xiufang

    2006-04-01

    Multimicrotubule chitosan conduits (M-conduits) were fabricated using novel molds and a thermal-induced phase-separation technique. Hollow chitosan conduits (H-conduits) with an inner diameter of 1-5 mm and a wall thickness of 0.2-1.0 mm were made, and then a novel mold composed of a styrofoam insulating pedestal with several holes and a stainless steel cover plate was used to make M-conduits. In brief, corresponding H-conduits were inserted upright into the holes of the styrofoam pedestal, and filled with chitosan solution, then rapidly covered with the precooled stainless steel cover plate, and then placed in a freezer. The styrofoam insulating pedestal enclosing the conduits could reduce the heat transfer through the side wall of the conduits. Gradual phase separation then occurred uniaxially in the presence of a unidirectional temperature gradient from the top end to the bottom end of the chitosan conduits. The phase-separated polymer/solvent systems were then dried in a freeze-dryer. The microtubule diameters were controlled by adjusting the polymer concentration and cooling temperature. In vitro characterization demonstrated that the mold-based multimicrotubule chitosan conduits possessed suitable mechanical strength, microtubule diameter distribution, porosity, swelling, biodegradability, and nerve cell affinity, and so they showed potential for application as nerve tissue engineering scaffolds. (c) 2005 Wiley Periodicals, Inc.

  20. Protective Effects of N-Acetyl Cysteine against Diesel Exhaust Particles-Induced Intracellular ROS Generates Pro-Inflammatory Cytokines to Mediate the Vascular Permeability of Capillary-Like Endothelial Tubes.

    Directory of Open Access Journals (Sweden)

    Chia-Yi Tseng

    Full Text Available Exposure to diesel exhaust particles (DEP is associated with pulmonary and cardiovascular diseases. Previous studies using in vitro endothelial tubes as a simplified model of capillaries have found that DEP-induced ROS increase vascular permeability with rearrangement or internalization of adherens junctional VE-cadherin away from the plasma membrane. This allows DEPs to penetrate into the cell and capillary lumen. In addition, pro-inflammatory cytokines are up-regulated and mediate vascular permeability in response to DEP. However, the mechanisms through which these DEP-induced pro-inflammatory cytokines increase vascular permeability remain unknown. Hence, we examined the ability of DEP to induce permeability of human umbilical vein endothelial cell tube cells to investigate these mechanisms. Furthermore, supplementation with NAC reduces ROS production following exposure to DEP. HUVEC tube cells contributed to a pro-inflammatory response to DEP-induced intracellular ROS generation. Endothelial oxidative stress induced the release of TNF-α and IL-6 from tube cells, subsequently stimulating the secretion of VEGF-A independent of HO-1. Our data suggests that DEP-induced intracellular ROS and release of the pro-inflammatory cytokines TNF- α and IL-6, which would contribute to VEGF-A secretion and disrupt cell-cell borders and increase vasculature permeability. Addition of NAC suppresses DEP-induced ROS efficiently and reduces subsequent damages by increasing endogenous glutathione.

  1. Conduit speed limit promotes formation of explosive `super slugs'

    Science.gov (United States)

    Llewellin, E. W.; Burton, M. R.; Mader, H. M.; Polacci, M.

    2014-12-01

    Strombolian activity - characterized by discrete, impulsive explosions - is common at basaltic volcanoes. The explosions are caused by the arrival, at the volcanic vent, of over-pressured `slugs' of magmatic gas, which have ascended the volcanic conduit. We present data from large-scale analogue experiments which reveal a previously-undescribed process which promotes the formation of large, highly over-pressured `super slugs'. We propose that these large slugs may drive the most violent Strombolian eruptions. Experiments were performed at the Large Analogue Volcano Apparatus at Durham University, UK, which comprises a 13m tall, 24cm diameter transparent conduit, surmounting a reservoir of analogue magma held at constant pressure. We simulate a vesiculation event deep in the sub-volcanic plumbing system by fluxing gas into the reservoir. Magma analogues with a range of viscosities are used, giving slug Reynolds numbers in the range 16 to 140,000. At moderate-to-high Reynolds number, we find that the gas rapidly self-organizes to form a conduit-filling lead slug; this slug ascends the column slowly, at a velocity limited by the flux of the falling film of liquid around it. Trailing bubbles, which ascend through the wake of the lead slug, rise much more rapidly. As they catch and coalesce with the lead slug, it grows and becomes increasingly over-pressured. This mechanism causes large slugs to form rapidly and we propose that it underpins the formation of the very large slugs that are responsible for the most explosive strombolian eruptions.

  2. Sensing turbulent flow and heat transport in a cave conduit

    Science.gov (United States)

    Kurtzman, D.; Lucia, F. J.; Jennings, J. W.; Wilson, J. L.; Tyler, S. W.; Jorgensen, A. M.; Dwivedi, R.; Boston, P.; Burger, P.

    2008-12-01

    Cave systems provide an extreme example of complex subsurface porous media, dominated by flow through an interconnected network of conduits. Whether water or air-filled, these flow systems have been largely observed subjectively, with only a few simple quantitative measurements of flow and pressure. In the spring of 2008 a joint campaign of New Mexico Tech and the University of Nevada Reno entered the 210m deep, ~8m "diameter," keyhole shaped, subhorizontal, Left Hand Tunnel, a large air-filled conduit in Carlsbad Caverns, New Mexico, with the intent to observe fluid flow with modern thermally-based instruments. The conduit experiences countercurrent, thermally stratified flow, with mean velocities in each layer less than 0.1m/s. It is part of a geothermally forced, large-scale convection cell. Two instruments were deployed. A distributed temperature sensing (DTS) fiber optic cable was stretched over 1km of the tunnel, and partially suspended by balloons to the roof, to sense spatial and low-frequency (0.01Hz) temporal variations of temperature with a resolution approaching 0.05 degree C. The mean temperature difference between layers was on the order of 0.5 degree and the caveward (subhorizontal) temperature gradient was 1 degree/400m. Influences of connecting subvertical shafts, wet areas of the cave, human activity, and diurnal fluctuations were observed. The second instrument, a 7m tall tower with an array of eight 300Hz thermocouple temperature sensors, with a sensitivity approaching 0.005 degree, was deployed 200m into the tunnel and used to detect high- frequency temperature fluctuations associated with turbulence and the stratified flow. Turbulence structure of each layer was similar. Temperature fluctuation (and turbulence intensity?) was significantly greater near the boundary between layers and its steep vertical gradient of mean temperature. Results from this 3-day campaign, as limited as they are, suggest that there is a wealth of information and

  3. Peripheral nerve regeneration within an asymmetrically porous PLGA/Pluronic F127 nerve guide conduit.

    Science.gov (United States)

    Oh, Se Heang; Kim, Jun Ho; Song, Kyu Sang; Jeon, Byeong Hwa; Yoon, Jin Hwan; Seo, Tae Beom; Namgung, Uk; Lee, Il Woo; Lee, Jin Ho

    2008-04-01

    Asymmetrically porous tubes with selective permeability and hydrophilicity as nerve guide conduits (NGCs) were fabricated using poly(lactic-co-glycolic acid) (PLGA) and Pluronic F127 by a modified immersion precipitation method. The inner surface of the tube had nano-size pores ( approximately 50nm) which can effectively prevent from fibrous tissue infiltration but permeate nutrients and retain neurotrophic factors, while the outer surface had micro-size pores ( approximately 50microm) which can allow vascular ingrowth for effective supply of nutrients into the tube. From the animal study using a rat model, the hydrophilized PLGA/F127 (3wt%) tube showed better nerve regeneration behavior than the control silicone or hydrophobic PLGA tubes, as investigated by immunohistochemical observation (by fluorescent microscopy with anti-neurofilament staining), histological observations (by light microscopy with toluidine blue staining and transmission electron microscopy), and electrophysiological evaluation (by compound muscle action potential measurement). This is probably owing to the effective permeation of nutrients and prevention of fibrous scar tissue invasion as well as the good mechanical strength of the tube to maintain a stable support structure for the nerve regeneration.

  4. Open system degassing, bubble rise and flow dynamics within volcanic conduits- an experimental approach

    Science.gov (United States)

    Pioli, L.; Azzopardi, B. J.; Bonadonna, C.; Marchetti, E.; Ripepe, M.

    2009-12-01

    Open conduit basaltic volcanoes are characterized by frequent eruptions, usually consisting in mild Strombolian and Hawaiian explosions, alternating years to months of quiescence periods, with degassing activity from the central conduit. Recent improvements of thermal, video, radar and acoustic monitoring techniques have provided new powerful tools for the study of degassing processes and made available geophysical and geochemical datasets for many central volcanoes, such as Stromboli, Etna (Italy), Kilauea (Hawaii), Villarrica (Chile). These studies revealed that degassing is an unsteady, often pulsatory process, characterized by fluctuations in both intensity and composition of the emitted gases. Unambiguous interpretation of monitoring data of surface activity in terms of conduit dynamics and flow processes is, however, not possible, due to partial knowledge of the physical processes controlling the dynamics of two-phase flows in magmas. We performed a series of experiments to gain further insights on the dynamics of the gas-bubble rise in magmas within a cylindrical conduit, their ability to segregate and coalesce and the effect of these processes on the degassing dynamics. The experiments consisted in generating fluxes at variable intensities of air through stagnant water or glucose syrup in a bubble column apparatus 6.5 m high and with a diameter of 24 cm diameter. Glucose syrup and water are Newtonian liquids with viscosity ranging from 2.4 to 204.0 Pa*s and from 1.7 to 0.2 10 -3 Pa*s respectively, depending on temperature. Air was inserted at the base of the column through a variable number (1 to 25) of 5mm-diameter nozzles reaching surficial gas velocities of up to 0.5 m/s. The activity of the bubble column was monitored through temperature, pressure, void fraction and acoustic measurements and filmed by a high-speed camera with maximum resolution of 800x600 pixels. Pressure fluctuations, vesicularity and acoustic signal were then analyzed and correlated

  5. Experimental investigation on momentum and drag reduction of Malaysian crop suspensions in closed conduit flow

    Science.gov (United States)

    Ahmed, S. M.; Kazi, S. N.; Khan, G.; Dahari, M.; Zubir, M. N. M.; Ahmad, P.; Montazer, E.

    2017-06-01

    The study of frictional losses in fiber suspension flow is one of the significant scientific interests as the characteristics of suspension flow considerably changes with shear stress, fiber source, and treatments applied on fibers. Pressure drop measurements were obtained for different Malaysian crop fiber suspensions flowing through a closed conduit. The generated data were gathered over a range of flow rates and suspension concentrations. It was found that the magnitude of the pressure drop of the fiber suspensions is dependent on the concentration, characteristics, and fiber source. Considerable drag reduction is obtained for concentration of 0.6 wt. % at high flow rates. Such a reduction of pressure drop at the particular concentrations and the flow rates is interesting and useful as these data can be used for design and optimization of fiber handling equipment and piping systems. Furthermore, the effect of different fibers, fiber properties and flexibility on pressure drop were studied.

  6. The mechanisms of refilling of xylem conduits and bleeding of tall birch during spring.

    Science.gov (United States)

    Westhoff, M; Schneider, H; Zimmermann, D; Mimietz, S; Stinzing, A; Wegner, L H; Kaiser, W; Krohne, G; Shirley, St; Jakob, P; Bamberg, E; Bentrup, F-W; Zimmermann, U

    2008-09-01

    Seasonal variations in osmolality and components of xylem sap in tall birch trees were determined using several techniques. Xylem sap was extracted from branch and trunk sections of 58 trees using the very rapid gas bubble-based jet-discharge method. The 5-cm long wood pieces were taken at short intervals over the entire tree height. The data show that large biphasic osmolality gradients temporarily exist within the conducting xylem conduits during leaf emergence (up to 272 mosmol x kg(-1) at the apex). These gradients (arising mainly from glucose and fructose) were clearly held within the xylem conduit as demonstrated by (1)H NMR imaging of intact twigs. Refilling experiments with benzene, sucrose infusion, electron and light microscopy, as well as (1)H NMR chemical shift microimaging provided evidence that the xylem of birch represents a compartment confined by solute-reflecting barriers (radial: lipid linings/lipid bodies; axial: presumably air-filled spaces). These features allow transformation of osmolality gradients into osmotic pressure gradients. Refilling of the xylem occurs by a dual mechanism: from the base (by root pressure) and from the top (by hydrostatic pressure generated by xylem-bound osmotic pressure). The generation of osmotic pressure gradients was accompanied by bleeding. Bleeding could be observed at a height of up to 21 m. Bleeding rates measured at a given height decreased exponentially with time. Evidence is presented that the driving force for bleeding is the weight of the static water columns above the bleeding point. The pressure exerted by the water columns and the bleeding volume depend on the water-filling status of (communicating) vessels.

  7. Evidence for Arbovirus Dissemination Conduits from the Mosquito (Diptera: Culicidae) Midgut

    National Research Council Canada - National Science Library

    Romoser, William

    2004-01-01

    .... Experiments using Venezuelan equine encephalitis viral replicon particles, which express the green fluorescent protein gene in cells, indicate the operation of tissue conduits, possibly involving...

  8. 3D-engineering of Cellularized Conduits for Peripheral Nerve Regeneration

    Science.gov (United States)

    Hu, Yu; Wu, Yao; Gou, Zhiyuan; Tao, Jie; Zhang, Jiumeng; Liu, Qianqi; Kang, Tianyi; Jiang, Shu; Huang, Siqing; He, Jiankang; Chen, Shaochen; Du, Yanan; Gou, Maling

    2016-08-01

    Tissue engineered conduits have great promise for bridging peripheral nerve defects by providing physical guiding and biological cues. A flexible method for integrating support cells into a conduit with desired architectures is wanted. Here, a 3D-printing technology is adopted to prepare a bio-conduit with designer structures for peripheral nerve regeneration. This bio-conduit is consisted of a cryopolymerized gelatin methacryloyl (cryoGelMA) gel cellularized with adipose-derived stem cells (ASCs). By modeling using 3D-printed “lock and key” moulds, the cryoGelMA gel is structured into conduits with different geometries, such as the designed multichannel or bifurcating and the personalized structures. The cryoGelMA conduit is degradable and could be completely degraded in 2-4 months in vivo. The cryoGelMA scaffold supports the attachment, proliferation and survival of the seeded ASCs, and up-regulates the expression of their neurotrophic factors mRNA in vitro. After implanted in a rat model, the bio-conduit is capable of supporting the re-innervation across a 10 mm sciatic nerve gap, with results close to that of the autografts in terms of functional and histological assessments. The study describes an indirect 3D-printing technology for fabricating cellularized designer conduits for peripheral nerve regeneration, and could lead to the development of future nerve bio-conduits for clinical use.

  9. Convection in a volcanic conduit recorded by bubbles

    Science.gov (United States)

    Carey, Rebecca J.; Manga, Michael; Degruyter, Wim; Gonnermann, Helge M.; Swanson, Donald; Houghton, Bruce F.; Orr, Tim; Patrick, Matthew R.

    2013-01-01

    Microtextures of juvenile pyroclasts from Kīlauea’s (Hawai‘i) early A.D. 2008 explosive activity record the velocity and depth of convection within the basaltic magma-filled conduit. We use X-ray microtomography (μXRT) to document the spatial distribution of bubbles. We find small bubbles (radii from 5 μm to 70 μm) in a halo surrounding larger millimeter-size bubbles. This suggests that dissolved water was enriched around the larger bubbles—the opposite of what is expected if bubbles grow as water diffuses into the bubble. Such volatile enrichment implies that the volatiles within the large bubbles were redissolving into the melt as they descended into the conduit by the downward motion of convecting magma within the lava lake. The thickness of the small bubble halo is ∼100–150 μm, consistent with water diffusing into the melt on time scales on the order of 103 s. Eruptions, triggered by rockfall, rapidly exposed this magma to lower pressures, and the haloes of melt with re-dissolved water became sufficiently supersaturated to cause nucleation of the population of smaller bubbles. The required supersaturation pressures are consistent with a depth of a few hundred meters and convection velocities of the order of 0.1 m s−1, similar to the circulation velocity observed on the surface of the Halema‘uma‘u lava lake.

  10. Documentation of a Conduit Flow Process (CFP) for MODFLOW-2005

    Science.gov (United States)

    Shoemaker, W. Barclay; Kuniansky, Eve L.; Birk, Steffen; Bauer, Sebastian; Swain, Eric D.

    2007-01-01

    This report documents the Conduit Flow Process (CFP) for the modular finite-difference ground-water flow model, MODFLOW-2005. The CFP has the ability to simulate turbulent ground-water flow conditions by: (1) coupling the traditional ground-water flow equation with formulations for a discrete network of cylindrical pipes (Mode 1), (2) inserting a high-conductivity flow layer that can switch between laminar and turbulent flow (Mode 2), or (3) simultaneously coupling a discrete pipe network while inserting a high-conductivity flow layer that can switch between laminar and turbulent flow (Mode 3). Conduit flow pipes (Mode 1) may represent dissolution or biological burrowing features in carbonate aquifers, voids in fractured rock, and (or) lava tubes in basaltic aquifers and can be fully or partially saturated under laminar or turbulent flow conditions. Preferential flow layers (Mode 2) may represent: (1) a porous media where turbulent flow is suspected to occur under the observed hydraulic gradients; (2) a single secondary porosity subsurface feature, such as a well-defined laterally extensive underground cave; or (3) a horizontal preferential flow layer consisting of many interconnected voids. In this second case, the input data are effective parameters, such as a very high hydraulic conductivity, representing multiple features. Data preparation is more complex for CFP Mode 1 (CFPM1) than for CFP Mode 2 (CFPM2). Specifically for CFPM1, conduit pipe locations, lengths, diameters, tortuosity, internal roughness, critical Reynolds numbers (NRe), and exchange conductances are required. CFPM1, however, solves the pipe network equations in a matrix that is independent of the porous media equation matrix, which may mitigate numerical instability associated with solution of dual flow components within the same matrix. CFPM2 requires less hydraulic information and knowledge about the specific location and hydraulic properties of conduits, and turbulent flow is approximated by

  11. Manufacture of porous biodegradable polymer conduits by an extrusion process for guided tissue regeneration

    Science.gov (United States)

    Widmer, M. S.; Gupta, P. K.; Lu, L.; Meszlenyi, R. K.; Evans, G. R.; Brandt, K.; Savel, T.; Gurlek, A.; Patrick, C. W. Jr; Mikos, A. G.; hide

    1998-01-01

    We have fabricated porous, biodegradable tubular conduits for guided tissue regeneration using a combined solvent casting and extrusion technique. The biodegradable polymers used in this study were poly(DL-lactic-co-glycolic acid) (PLGA) and poly(L-lactic acid) (PLLA). A polymer/salt composite was first prepared by a solvent casting process. After drying, the composite was extruded to form a tubular construct. The salt particles in the construct were then leached out leaving a conduit with an open-pore structure. PLGA was studied as a model polymer to analyze the effects of salt weight fraction, salt particle size, and processing temperature on porosity and pore size of the extruded conduits. The porosity and pore size were found to increase with increasing salt weight fraction. Increasing the salt particle size increased the pore diameter but did not affect the porosity. High extrusion temperatures decreased the pore diameter without altering the porosity. Greater decrease in molecular weight was observed for conduits manufactured at higher temperatures. The mechanical properties of both PLGA and PLLA conduits were tested after degradation in vitro for up to 8 weeks. The modulus and failure strength of PLLA conduits were approximately 10 times higher than those of PLGA conduits. Failure strain was similar for both conduits. After degradation for 8 weeks, the molecular weights of the PLGA and PLLA conduits decreased to 38% and 43% of the initial values, respectively. However, both conduits maintained their shape and did not collapse. The PLGA also remained amorphous throughout the time course, while the crystallinity of PLLA increased from 5.2% to 11.5%. The potential of seeding the conduits with cells for transplantation or with biodegradable polymer microparticles for drug delivery was also tested with dyed microspheres. These porous tubular structures hold great promise for the regeneration of tissues which require tubular scaffolds such as peripheral nerve

  12. Linear permeability evolution of expanding conduits due to feedback between flow and fast phase change

    Science.gov (United States)

    Wang, Lichun; Cardenas, M. Bayani

    2017-05-01

    Conduits are ubiquitous and critical pathways for many fluids relevant for geophysical processes such as magma, water, and gases. Predicting flow through conduits is challenging when the conduit geometry coevolves with the flow. We theoretically show that the permeability (k) of a conduit whose walls are eroding due to fast phase change increases linearly with time because of a self-reinforcing mechanism. This simple result is surprising given complex feedbacks between flow, transport, and phase change. The theory is congruent with previous experimental observations of fracture dissolution in calcite. Supporting computational fracture dissolution experiments showed that k only slightly increases until the dissolution front reaches the narrowest conduit constriction, after which the linear evolution of k manifests. The theory holds across multiple scales and a broad range of Peclet and Damkohler numbers and thus advances the prediction of dynamic mass fluxes through expanding conduits in various geologic and environmental settings.Plain Language SummaryGeological conduits are ubiquitous present in the subsurface. In many situations, these conduits may enlarge through time due to erosion of its walls by dissolution and melting. This leads to strongly coupled flow and reactive transport processes where the flow dictates the wall's erosion and vice versa. As the conduit expands, so does its permeability and thus flow. Thus, predicting fluid flow and relevant transport processes through expanding conduits is challenging. In this study, we presented a theory for the linear time dependence of permeability for expanding conduits. The theory is congruent with previous observations from fracture dissolution in calcite. An additional series of our own computational experiments also aligns with the theory. The theory will be of interest to geoscientists and engineers in many fields such as hydrology, glaciology, and petroleum engineering, to name a few.

  13. Dynamics of Long-distance Signaling via Plant Vascular Tissues

    Directory of Open Access Journals (Sweden)

    Michitaka eNotaguchi

    2015-03-01

    Full Text Available Plant vascular systems are constructed by specific cell wall modifications through which cells are highly specialized to make conduits for water and nutrients. Xylem vessels are formed by thickened cell walls that remain after programmed cell death, and serve as water conduits from the root to the shoot. In contrast, phloem tissues consist of a complex of living cells, including sieve tube elements and their neighboring companion cells, and translocate photosynthetic assimilates from mature leaves to developing young tissues. Intensive studies on the content of vascular flow fluids have unveiled that plant vascular tissues transport various types of gene product, and the transport of some provides the molecular basis for the long-distance communications. Analysis of xylem sap has demonstrated the presence of proteins in the xylem transpiration stream. Recent studies have revealed that CLE and CEP peptides secreted in the roots are transported to above ground via the xylem in response to plant-microbe interaction and soil nitrogen starvation, respectively. Their leucine-rich repeat transmembrane receptors localized in the shoot phloem are required for relaying the signal from the shoot to the root. These findings well fit to the current scenario of root-to-shoot-to-root feedback signaling, where peptide transport achieves the root-to-shoot signaling, the first half of the signaling process. Meanwhile, it is now well evidenced that proteins and a range of RNAs are transported via the phloem translocation system, and some of those can exert their physiological functions at their destinations, including roots. Thus, plant vascular systems may serve not only as conduits for the translocation of essential substances but also as long-distance communication pathways that allow plants to adapt to changes in internal and external environments at the whole plant level.

  14. Characterization of molecule and particle transport through nanoscale conduits

    Science.gov (United States)

    Alibakhshi, Mohammad Amin

    Nanofluidic devices have been of great interest due to their applications in variety of fields, including energy conversion and storage, water desalination, biological and chemical separations, and lab-on-a-chip devices. Although these applications cross the boundaries of many different disciplines, they all share the demand for understanding transport in nanoscale conduits. In this thesis, different elusive aspects of molecule and particle transport through nanofluidic conduits are investigated, including liquid and ion transport in nanochannels, diffusion- and reaction-governed enzyme transport in nanofluidic channels, and finally translocation of nanobeads through nanopores. Liquid or solvent transport through nanoconfinements is an essential yet barely characterized component of any nanofluidic systems. In the first chapter, water transport through single hydrophilic nanochannels with heights down to 7 nm is experimentally investigated using a new measurement technique. This technique has been developed based on the capillary flow and a novel hybrid nanochannel design and is capable of characterizing flow in both single nanoconduits as well as nanoporous media. The presence of a 0.7 nm thick hydration layer on hydrophilic surfaces and its effect on increasing the hydraulic resistance of the nanochannels is verified. Next, ion transport in a new class of nanofluidic rectifiers is theoretically and experimentally investigated. These so called nanofluidic diodes are nanochannels with asymmetric geometries which preferentially allow ion transport in one direction. A nondimensional number as a function of electrolyte concentration, nanochannel dimensions, and surface charge is derived that summarizes the rectification behavior of this system. In the fourth chapter, diffusion- and reaction-governed enzyme transport in nanofluidic channels is studied and the theoretical background necessary for understanding enzymatic activity in nanofluidic channels is presented. A

  15. Plumbing the Aquatic Conduit for Terrestrial Carbon: How far can we get with Hydrological Connectivity?

    Science.gov (United States)

    Bishop, K. H.; Campeau, A.; Billett, M. F.; Wallin, M.

    2016-12-01

    The water cycle is maddeningly difficultyto pin down with the level of detail that is desired for resolving issues about the fate of pollutants, nutrient cycling and the global carbon balance, etc. "Connectivity" is increasingly talked of in hydrology and water resources management as a way to better conceptualize how different parts of the catchment dynamically interact to influence runoff generation and water quality. Runoff is a major C flux (aquatic conduit) that is particularly sensitive to changes in climate and hydrological regimes. This paper uses three dimensions of connectivity (vertical, latitudinal and longitudinal), to plumb the sources of carbon leaving a boreal landscape via the aquatic conduit. We used the distributed sources and age of aquatic C export to help assess the role and stability of a boreal landscape in the global C cycle. We combined hydrometric data and mass balances with isotopic tracers of water and carbon, including both radiogenic (14C) and stable carbon isotopes (δ13C) of DOC, CO2 and CH4 in catchment soils and the stream network to define the connectivity of riparian, peatland and upland sources to the carbon in runoff throughout the year. The radiocarbon age of DOC, CO2 and CH4were predominantly modern, even in peat catotelm, but with localized excursions to millennial ages. The sources and processes that transport dissolved C species varied strongly with flow rates and the associated patterns of connectivity, mediated by seasonal variation that influence carbon cycling. The age of the C and other tracers exported to streams enabled us to "connect" the aquatic C exports to their origins in the mosaic of landscape elements. The effort also identified ways in which the concept of hydrological connectivity can be refined to strengthen the testing of biogeochemical hypotheses across temporal and spatial scales in specific landscapes.

  16. Numerical simulation of explosive volcanic eruptions from the conduit flow to global atmospheric scales

    Directory of Open Access Journals (Sweden)

    G. G. J. Ernst

    2005-06-01

    Full Text Available Volcanic eruptions are unsteady multiphase phenomena, which encompass many inter-related processes across the whole range of scales from molecular and microscopic to macroscopic, synoptic and global. We provide an overview of recent advances in numerical modelling of volcanic effects, from conduit and eruption column processes to those on the Earth s climate. Conduit flow models examine ascent dynamics and multiphase processes like fragmentation, chemical reactions and mass transfer below the Earth surface. Other models simulate atmospheric dispersal of the erupted gas-particle mixture, focusing on rapid processes occurring in the jet, the lower convective regions, and pyroclastic density currents. The ascending eruption column and intrusive gravity current generated by it, as well as sedimentation and ash dispersal from those flows in the immediate environment of the volcano are examined with modular and generic models. These apply simplifications to the equations describing the system depending on the specific focus of scrutiny. The atmospheric dispersion of volcanic clouds is simulated by ash tracking models. These are inadequate for the first hours of spreading in many cases but focus on long-range prediction of ash location to prevent hazardous aircraft - ash encounters. The climate impact is investigated with global models. All processes and effects of explosive eruptions cannot be simulated by a single model, due to the complexity and hugely contrasting spatial and temporal scales involved. There is now the opportunity to establish a closer integration between different models and to develop the first comprehensive description of explosive eruptions and of their effects on the ground, in the atmosphere, and on the global climate.

  17. Frictional melting dynamics in the upper conduit: A chemical answer to a complex physical question

    Science.gov (United States)

    Henton De Angelis, S.; Lavallee, Y.; Kendrick, J. E.; Hornby, A.; von Aulock, F. W.; Clesham, S.; Hirose, T.; Perugini, D.

    2013-12-01

    During volcanic eruptions the generation of frictional heat along the walls of the shallow conduit leads to melting of the rocks along the slip interface. Frictional melting has previously been described as a process out of thermodynamic equilibrium, but upon slip and mingling of the melt batches, homogeneity can be achieved, and may have an h important rheological control on the dynamics of slip. To test melt homogenization in the frictional melt zones of volcanic conduits we performed constant-rate slip experiments under controlled stress conditions using a high-velocity rotary shear apparatus. Volcanic dome samples from three different volcanoes (Volcán De Colima, Soufrière Hills Volcano and Santiaguito Volcano) were investigated. Each sample was subjected to a stress of 1 MPa and slip rate of 1 m/s. For each sample set 5 experiments were conducted: 1) experiment stopped at the onset of melting; 2) experiment stopped on the formation of a full melt layer; 3) experiment stopped after 5m of slip at steady state conditions; 4) experiment stopped after 10m of slip at steady state conditions; 5) experiment stopped after 15m of slip at steady state conditions. We analyzed the resulting proto-melt zones using micron sized X-ray spectroscopy in the high-brightness synchrotron beamline I18 (at Diamond Light Source UK). Particular focus was given to the concentration variance analysis of Rare Earth Elements as their mobilities can be used to precisely quantify the degree and timescale of homogenisation involved during frictional melting. This study refines our understanding of the chemical process of melting and mixing which carry important consequences for the rheological control on the physical dynamics of slip.

  18. Autologous alternative veins may not provide better outcomes than prosthetic conduits for below-knee bypass when great saphenous vein is unavailable.

    Science.gov (United States)

    Avgerinos, Efthymios D; Sachdev, Ulka; Naddaf, Abdallah; Doucet, Dannielle R; Mohapatra, Abhisekh; Leers, Steven A; Chaer, Rabih A; Makaroun, Michel S

    2015-08-01

    There is a need to better define the role of alternative autologous vein (AAV) segments over contemporary prosthetic conduits in patients with critical limb ischemia when great saphenous vein (GSV) is not available for use as the bypass conduit. Consecutive patients who underwent bypass to infrageniculate targets between 2007 and 2011 were categorized in three groups: GSV, AAV, and prosthetic. The primary outcome was graft patency. The secondary outcome was limb salvage. Cox proportional hazards regression was used to adjust for baseline confounding variables. A total of 407 infrainguinal bypasses to below-knee targets were analyzed; 255 patients (63%) received a single-segment GSV, 106 patients (26%) received an AAV, and 46 patients (11%) received a prosthetic conduit. Baseline characteristics were similar among groups, with the exception of popliteal targets and anticoagulation use being more frequent in the prosthetic group. Primary patency at 2 and 5 years was estimated at 47% and 32%, respectively, for the GSV group; 24% and 23% for the AAV group; and 43% and 38% for the prosthetic group. Primary assisted patency at 2 and 5 years was estimated at 71% and 55%, respectively, for the GSV group; 53% and 51% for the AAV group; and 45% and 40% for the prosthetic group. Secondary patency at 2 and 5 years was estimated at 75% and 60%, respectively, for the GSV group; 57% and 55% for the AAV group; and 46% and 41% for the prosthetic group. In Cox analysis, primary patency (hazard ratio [HR], 0.55; P prosthetic grafts except for the primary patency, for which prosthetic was protective (HR, 0.38; P Limb salvage was similar among groups. AAV conduits may not offer a significant patency advantage in midterm follow-up over prosthetic bypasses. Copyright © 2015 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.

  19. 30 CFR 75.700 - Grounding metallic sheaths, armors, and conduits enclosing power conductors.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Grounding metallic sheaths, armors, and conduits enclosing power conductors. 75.700 Section 75.700 Mineral Resources MINE SAFETY AND HEALTH... Grounding § 75.700 Grounding metallic sheaths, armors, and conduits enclosing power conductors. All metallic...

  20. [Urinary diversion and colon: transverse conduit and transverse pouch].

    Science.gov (United States)

    Ahyai, S A; Sayedahmed, K; Engel, O; Chun, F; Dahlem, R; Fisch, M

    2012-07-01

    In the vast majority of cases the terminal ileum is used for incontinent or continent bladder substitution. However, in irradiated patients the use of ileum segments or the ileocecal reservoir is associated with an increased risk of early and late complications. For this reason these patients should be treated with a transverse conduit or pouch as the method of choice if urinary diversion is indicated. The superior outcome of this high urinary diversion is due to the use of non-irradiated segments of the colon and ureter. The lack of experience in large bowel surgery by today's urologists should be compensated by training or referral of these high risk patients to a specialized center.

  1. Investigating the influence of conduit residues on polyurethane plates

    Directory of Open Access Journals (Sweden)

    Rachel Faverzani Magnago

    Full Text Available Abstract Converting waste into a product similar to the original one or into another useful product is to save energy, protect natural resources, and bring back to the production cycle what was discarded. In that direction, new polyurethane-based composites have been developed by incorporating 5%, 10%, 15%, and 20% PVC conduit discarded by the construction industry. The objective of this study was to investigate the interaction between the phases of waste incorporation and the effect upon the new material properties. The samples were produced by the polycondensation process. Microstructural analysis revealed a reduction in pore size across the polymer matrix. However, there were no changes in thermal insulation, water absorption, compressive strength, and burning rate tests and in the thermogravimetric analysis and differential scanning calorimetry. The results from this study showed that the replacement of raw material by waste did not affect its properties.

  2. Electrospun silk-polyaniline conduits for functional nerve regeneration in rat sciatic nerve injury model.

    Science.gov (United States)

    Das, Suradip; Sharma, Manav; Saharia, Dhiren; Sarma, Kushal Konwar; Muir, Elizabeth M; Bora, Utpal

    2017-08-17

    The present study describes the fabrication of polyaniline-silk fibroin (PASF) nanocomposite-based nerve conduits and their subsequent implantation in a rat sciatic nerve injury model for peripheral nerve regeneration. This is the first in vivo study of polyaniline-based nerve conduits describing the safety and efficacy of the conduits in treating peripheral nerve injuries. The nanocomposite was synthesized by electrospinning a mixture of silk fibroin protein and polyaniline wherein the silk nanofibers were observed to be uniformly coated with polyaniline nanoparticles. Tubular shaped nerve conduits were subsequently formed by multiple rolling of the electrospun sheet over a stainless steel mandrel. The conduits were characterized in vitro for their physico-chemical properties as well as their compatibility with rat Schwann cells. Upon implantation in a 10 mm sciatic nerve injury model, the conduits were evaluated for their neuro-regenerative potential through extensive electrophysiological studies and monitoring of gait pattern over a course of 12 months. Gross examination, histological and ultra-structure analyses of the conduits and the regenerated nerve were also performed to evaluate morphological regeneration of transected nerve. PASF nanocomposite conduits seeded with Schwann cell (cell seeded PASF) exhibited excellent nerve conduction velocity (NCV) (50 m s(-1)), compound muscle action potential (CMAP) (12.8 mV), motor unit potential (MUP) (124 μV), growth of healthy tissue along the nerve gap and thick myelination of axons 12 months after implantation indicating enhanced neuro-regeneration. The excellent functional recovery achieved by animals implanted with cell seeded PASF conduits (86.2% NCV; 80.00% CMAP; 76.07% MUP) are superior to outcomes achieved previously with similar electrically conductive conduits. We believe that the present study would encourage further research in developing electrically active neural implants using synthetic conducting

  3. Cavitation Resistance in Seedless Vascular Plants: The Structure and Function of Interconduit Pit Membranes.

    Science.gov (United States)

    Brodersen, Craig; Jansen, Steven; Choat, Brendan; Rico, Christopher; Pittermann, Jarmila

    2014-06-01

    Plant water transport occurs through interconnected xylem conduits that are separated by partially digested regions in the cell wall known as pit membranes. These structures have a dual function. Their porous construction facilitates water movement between conduits while limiting the spread of air that may enter the conduits and render them dysfunctional during a drought. Pit membranes have been well studied in woody plants, but very little is known about their function in more ancient lineages such as seedless vascular plants. Here, we examine the relationships between conduit air seeding, pit hydraulic resistance, and pit anatomy in 10 species of ferns (pteridophytes) and two lycophytes. Air seeding pressures ranged from 0.8 ± 0.15 MPa (mean ± sd) in the hydric fern Athyrium filix-femina to 4.9 ± 0.94 MPa in Psilotum nudum, an epiphytic species. Notably, a positive correlation was found between conduit pit area and vulnerability to air seeding, suggesting that the rare-pit hypothesis explains air seeding in early-diverging lineages much as it does in many angiosperms. Pit area resistance was variable but averaged 54.6 MPa s m-1 across all surveyed pteridophytes. End walls contributed 52% to the overall transport resistance, similar to the 56% in angiosperm vessels and 64% in conifer tracheids. Taken together, our data imply that, irrespective of phylogenetic placement, selection acted on transport efficiency in seedless vascular plants and woody plants in equal measure by compensating for shorter conduits in tracheid-bearing plants with more permeable pit membranes. © 2014 American Society of Plant Biologists. All Rights Reserved.

  4. Engineering a multimodal nerve conduit for repair of injured peripheral nerve

    Science.gov (United States)

    Quigley, A. F.; Bulluss, K. J.; Kyratzis, I. L. B.; Gilmore, K.; Mysore, T.; Schirmer, K. S. U.; Kennedy, E. L.; O'Shea, M.; Truong, Y. B.; Edwards, S. L.; Peeters, G.; Herwig, P.; Razal, J. M.; Campbell, T. E.; Lowes, K. N.; Higgins, M. J.; Moulton, S. E.; Murphy, M. A.; Cook, M. J.; Clark, G. M.; Wallace, G. G.; Kapsa, R. M. I.

    2013-02-01

    Injury to nerve tissue in the peripheral nervous system (PNS) results in long-term impairment of limb function, dysaesthesia and pain, often with associated psychological effects. Whilst minor injuries can be left to regenerate without intervention and short gaps up to 2 cm can be sutured, larger or more severe injuries commonly require autogenous nerve grafts harvested from elsewhere in the body (usually sensory nerves). Functional recovery is often suboptimal and associated with loss of sensation from the tissue innervated by the harvested nerve. The challenges that persist with nerve repair have resulted in development of nerve guides or conduits from non-neural biological tissues and various polymers to improve the prognosis for the repair of damaged nerves in the PNS. This study describes the design and fabrication of a multimodal controlled pore size nerve regeneration conduit using polylactic acid (PLA) and (PLA):poly(lactic-co-glycolic) acid (PLGA) fibers within a neurotrophin-enriched alginate hydrogel. The nerve repair conduit design consists of two types of PLGA fibers selected specifically for promotion of axonal outgrowth and Schwann cell growth (75:25 for axons; 85:15 for Schwann cells). These aligned fibers are contained within the lumen of a knitted PLA sheath coated with electrospun PLA nanofibers to control pore size. The PLGA guidance fibers within the nerve repair conduit lumen are supported within an alginate hydrogel impregnated with neurotrophic factors (NT-3 or BDNF with LIF, SMDF and MGF-1) to provide neuroprotection, stimulation of axonal growth and Schwann cell migration. The conduit was used to promote repair of transected sciatic nerve in rats over a period of 4 weeks. Over this period, it was observed that over-grooming and self-mutilation (autotomy) of the limb implanted with the conduit was significantly reduced in rats implanted with the full-configuration conduit compared to rats implanted with conduits containing only an alginate

  5. Poly(lactic-co-glycolic acid) conduit for repair of injured sciatic nerve: A mechanical analysis.

    Science.gov (United States)

    Yu, Tao; Zhao, Changfu; Li, Peng; Liu, Guangyao; Luo, Min

    2013-07-25

    Tensile stress and tensile strain directly affect the quality of nerve regeneration after bridging nerve defects by poly(lactic-co-glycolic acid) conduit transplantation and autogenous nerve grafting for sciatic nerve injury. This study collected the sciatic nerve from the gluteus maximus muscle from fresh human cadaver, and established 10-mm-long sciatic nerve injury models by removing the ischium, following which poly(lactic-co-glycolic acid) conduits or autogenous nerve grafts were transplanted. Scanning electron microscopy revealed that the axon and myelin sheath were torn, and the vessels of basilar membrane were obstructed in the poly(lactic-co-glycolic acid) conduit-repaired sciatic nerve following tensile testing. There were no significant differences in tensile tests with autogenous nerve graft-repaired sciatic nerve. Following poly(lactic-co-glycolic acid) conduit transplantation for sciatic nerve repair, tensile test results suggest that maximum tensile load, maximum stress, elastic limit load and elastic limit stress increased compared with autogenous nerve grafts, but elastic limit strain and maximum strain decreased. Moreover, the tendencies of stress-strain curves of sciatic nerves were similar after transplantation of poly(lactic-co-glycolic acid) conduits or autogenous nerve grafts. Results showed that after transplantation in vitro for sciatic nerve injury, poly(lactic-co-glycolic acid) conduits exhibited good intensity, elasticity and plasticity, indicating that poly(lactic-co-glycolic acid) conduits are suitable for sciatic nerve injury repair.

  6. Evidence for generation of a large amount of nitric oxide-like vascular smooth muscle relaxant by cholesterol-rich neutrophils.

    Science.gov (United States)

    Mehta, J L; Lawson, D L; Nicolini, F A; Cain, D A; Mehta, P; Schreier, H

    1990-11-30

    To determine the effect of cholesterol incorporation on the ability of neutrophils to generate superoxide radicals and nitric oxide-like vasorelaxant material, isolated human neutrophils were incubated with cholesterol-rich liposomes, which increased total cholesterol content by 141% and esterified cholesterol content by 523%. Cholesterol loading resulted in 5 to 7 fold increase in cytosolic calcium in resting as well as in PMA or f-MLP-stimulated cells, but a marked (P less than 0.01) reduction in both PMA- and f-MLP-stimulated superoxide radical generation by these cells. Nitric oxide-like activity measured as relaxation of rat aortic rings was more pronounced (P less than 0.02) in cholesterol-rich than in cholesterol-poor cells. The greater relaxation of aortic rings in response to cholesterol-rich neutrophils was observed in rings with or without intact endothelium, and was potentiated by superoxide dismutase and inhibited by oxyhemoglobin as well as L-NMMA, thus suggesting that the vasorelaxant material was nitric oxide. The greater generation of nitric oxide by cholesterol-rich neutrophils occurs perhaps in response to increased cytosolic calcium.

  7. Effect of SR manipulation on conduit artery dilation in humans.

    Science.gov (United States)

    Carter, Howard H; Dawson, Ellen A; Birk, Gurpreet K; Spence, Angela L; Naylor, Louise H; Cable, N Timothy; Thijssen, Dick H J; Green, Daniel J

    2013-01-01

    The impact of manipulating shear stress on conduit artery vasodilation has not been comprehensively described in vivo. We hypothesized that manipulation of SR through the brachial and radial arteries would be associated with corresponding changes in diameter. We performed a series of studies involving the following: (1) leg cycle exercise at increasing intensities (≈70 and 85% maximum heart rate [HRmax]) with simultaneous bilateral measurement of SR in the radial arteries; (2) leg cycle exercise for 30 minutes at 80% HRmax with simultaneous bilateral measurement of velocity and diameter in the brachial arteries; and (3) bilateral forearm heating for 30 minutes with simultaneous bilateral measurement of brachial artery diameter and blood velocity. Cycling and forearm heating interventions were performed in the presence of unilateral cuff inflation throughout the experiment, or starting during the intervention (15 minutes), to manipulate SR responses. Cuff placement was associated with lower radial artery SR responses (cuffed versus uncuffed, 248±49 versus 349±105 L/s 85% HRmax; P<0.01), and diameter responses were similarly attenuated (2.45±0.30 versus 2.78±0.20 mm 85% HRmax; P<0.05). Exercise performed at 80% HRmax in the presence of unilateral cuff inflation also reduced brachial artery SR (cuffed versus uncuffed; 258±107 versus 454±157 L/s; P<0.01) and diameter (3.96±0.39 versus 4.20±0.45 mm). Finally, cuff inflation decreased the impact of forearm heating on brachial SR (cuffed versus uncuffed; 262±97 versus 440±106 L/s; P<0.01) and diameter (4.35±0.54 versus 4.87±0.47 mm; P<0.05). Similar significant differences between the cuffed and uncuffed limbs in SR and diameter were observed when cuff inflation occurred during exercise or heating. Our findings strongly implicate SR as an important stimulus to increase conduit artery diameter in humans.

  8. Hydrothermal Alteration of the Mt Unzen Conduit (Shimabara/Japan)

    Science.gov (United States)

    Yilmaz, T. I.; Mayer, K.; Hess, K. U.; Janots, E.; Gilg, H. A.; Dingwell, D. B.

    2016-12-01

    Investigations were carried out on hydrothermally altered coherent dacitic dykes samples from (USDP-4) drill core at Mt Unzen stratovolcano (Shimabara/Japan). XRF, XRD, EMPA, and C-O-isotope analysis led to insights concerning chemistry, mineralogy, and intensity of alteration as well as the origin of carbonate-precipitating fluids. Additionally a textural characterization of the occurring replacement features in the magma conduit zone was performed. The occurrence of the main secondary phases such as chlorite, pyrite, carbonates, and R1 (Reichweite parameter) illite-smectite indicate a weak to moderate propylitic to phyllic hydrothermal alteration. The dacitic samples of the dykes show different hydrothermal alteration features: (i) carbonate pseudomorphs after hornblende as well as core and zonal textures due to replacement of plagioclase by R1 illite-smectite, (ii) colloform banded fracture fillings and fillings in dissolution vugs, and (iii) chlorite and R1 illite-smectite in the groundmass. Carbonates in fractures comprise iron-rich dolomite solid solutions ("ankerite") and calcite. Isotopic values of d13Cvpdb = -4.59 ± 0.6‰ and d18Ovpdb = -21.73 ± 0.5‰ indicate a hydrothermal-magmatic origin for the carbonate formation. The chlorite-carbonate-pyrite index (CCPI) and the Ishikawa alteration index (AI), applied to the investigated samples show significant differences (CCPI=52.7-57.8; AI=36.1-40.6) indicating their different degree of alteration. According to Nakada et al., 2005, the C13 to C16 dykes represent the feeder dyke from the latest eruption (1991-1995) whereas C8 represents an earlier dyke feeder dyke from an older eruption. Weakest conduit alteration, which was obtained in samples C16-1-5 and C13-2-5, correlates with the alteration degree of the pristine dome rocks. Highest CCPI value was determined for sample C14-1-5 and the highest AI value was determined for sample C15-2-6. The degrees of alteration do not indicate highest alteration of the

  9. Plant Vascular Biology 2013: vascular trafficking.

    Science.gov (United States)

    Ursache, Robertas; Heo, Jung-Ok; Helariutta, Ykä

    2014-04-01

    About 200 researchers from around the world attended the Third International Conference on Plant Vascular Biology (PVB 2013) held in July 2013 at the Rantapuisto Conference Center, in Helsinki, Finland (http://www.pvb2013.org). The plant vascular system, which connects every organ in the mature plant, continues to attract the interest of researchers representing a wide range of disciplines, including development, physiology, systems biology, and computational biology. At the meeting, participants discussed the latest research advances in vascular development, long- and short-distance vascular transport and long-distance signalling in plant defence, in addition to providing a context for how these studies intersect with each other. The meeting provided an opportunity for researchers working across a broad range of fields to share ideas and to discuss future directions in the expanding field of vascular biology. In this report, the latest advances in understanding the mechanism of vascular trafficking presented at the meeting have been summarized.

  10. Obstruction of an ileal urinary conduit in an incarcerated right inguinal hernia

    Science.gov (United States)

    Weston, PMT

    2015-01-01

    We present the case of a 72-year-old man with a history of anuria from his ileal conduit 15 months following its formation. That conduit had become incarcerated in a right-sided ingunial hernia. The patient presented with anuria and an acute kidney injury. A clincal diagnosis of an incarcerated hernia was made, and he was taken to theatre for reduction and repair of the hernia. On removal of the conduit from the hernial sac, it began to drain immediately. He made a full recovery, with normalisation of his renal function. PMID:26491738

  11. Molecular Mechanisms Controlling Vascular Lumen Formation in Three-Dimensional Extracellular Matrices

    Science.gov (United States)

    Sacharidou, Anastasia; Stratman, Amber N.; Davis, George E.

    2011-01-01

    Considerable progress has been made toward a molecular understanding of how cells form lumen and tube structures in three-dimensional (3D) extracellular matrices (ECM). This progress has occurred through work performed with endothelial and epithelial cell models using both in vitro and in vivo approaches. Despite the apparent similarities between endothelial and epithelial cell lumen and tube formation mechanisms, there are clear distinctions that directly relate to their functional differences. This review will focus on endothelial cell (EC) lumen formation mechanisms which control blood vessel formation during development and postnatal life. Of great interest is that an EC lumen signaling complex has been identified which controls human EC lumen and tube formation in 3D matrices and which coordinates integrin-ECM contacts, cell surface proteolysis, cytoskeletal rearrangements, and cell polarity. This complex consists of the collagen-binding integrin α2β1, the collagen-degrading membrane-type 1 matrix metalloproteinase (MT1-MMP), junction adhesion molecule (Jam)C, JamB, polarity proteins Par3 and Par6b, and the Rho GTPase Cdc42-GTP. These interacting proteins are necessary to stimulate 3D matrix-specific signaling events (including activation of protein kinase cascades that regulate the actin and microtubule cytoskeletons) to control the formation of EC lumens and tube networks. Also, EC lumen formation is directly coupled to the generation of vascular guidance tunnels, enzymatically generated ECM conduits that facilitate EC tube remodeling and maturation. Mural cells such as pericytes are recruited along EC tubes within these tunnel spaces to control ECM remodeling events resulting in vascular basement membrane matrix assembly, a key step in tube maturation and stabilization. PMID:21997121

  12. A Cable-in-Conduit Superconductor for Pulsed Accelerator Magnets

    CERN Document Server

    Bottura, L; Fischer, E; Kauschke, M; Moritz, G; Vysotsky, V S; Sytnikov, V E; Wilson, M

    2005-01-01

    Superconducting magnets for future accelerators such as the SIS-100 ring of the International Accelerator Facility at GSI-Darmstadt, or a superconducting injector at the LHC, require that the magnetic field is pulsed with high repetition rate and high reliability over periods of several years. As an example the SIS-100 at the IAF is planned to be operated up to 2 T at 4 T/s for more than 100 millions cycles. Achieving these objectives requires that the superconductor has an excellent mechanical stability as well as a sufficient energy margin to tolerate foreseen and unforeseen energy inputs. In addition the cryogenic loss must be controlled at low levels, while the field errors due to coupling currents must be compatible with the beam dynamics requirements. In this paper we describe a cable-in-conduit design that is suitable for the challenging operating conditions described above, we give the expected performances and report on the on-going manufacturing demonstration and planned supporting tests.

  13. Medical interpreters and bilingual school staff: Potential disaster information conduits?

    Science.gov (United States)

    Ike, Brooke R; Calhoun, Rebecca; Angulo, Antoinette S; Meischke, Hendrika; Senturia, Kirsten D

    2015-01-01

    Dissemination of trusted disaster information to limited English proficient (LEP) communities may mitigate the negative effects these higher risk communities experience in disasters. For immigrant communities, disaster messages may be perceived with skepticism, and fear of public officials may affect compliance with disaster messages. This study explores whether medical interpreters (MIs) and bilingual school staff (BSS) are already informal information sources for LEP communities, and could their connection to both public service organizations and LEP communities make them ideal efficient, trusted disaster information conduits for LEP communities. The authors conducted a mixed methods study, which included MI individual interviews, Latino community focus groups, an MI employer survey, and school administrator interviews. To ensure diversity in the sample, data were collected in both Los Angeles and Seattle. MIs, MI employers, and schools are willing to communicate disaster information to LEP communities. MIs and BSS are connected to and share information with LEP communities. Latino LEP communities are eager for more disaster information and sources. The study adds to the evidence that a multipronged approach that includes collaborating with professionals linked to immigrant communities, such as MIs and BSS, could be an effective method of disaster information dissemination. Working with MIs and BSS as part of a wider dissemination strategy would promote a community-based interpersonal flow of information that would contribute to LEP community's trust in the message.

  14. Bioprinting for vascular and vascularized tissue biofabrication.

    Science.gov (United States)

    Datta, Pallab; Ayan, Bugra; Ozbolat, Ibrahim T

    2017-03-15

    Bioprinting is a promising technology to fabricate design-specific tissue constructs due to its ability to create complex, heterocellular structures with anatomical precision. Bioprinting enables the deposition of various biologics including growth factors, cells, genes, neo-tissues and extra-cellular matrix-like hydrogels. Benefits of bioprinting have started to make a mark in the fields of tissue engineering, regenerative medicine and pharmaceutics. Specifically, in the field of tissue engineering, the creation of vascularized tissue constructs has remained a principal challenge till date. However, given the myriad advantages over other biofabrication methods, it becomes organic to expect that bioprinting can provide a viable solution for the vascularization problem, and facilitate the clinical translation of tissue engineered constructs. This article provides a comprehensive account of bioprinting of vascular and vascularized tissue constructs. The review is structured as introducing the scope of bioprinting in tissue engineering applications, key vascular anatomical features and then a thorough coverage of 3D bioprinting using extrusion-, droplet- and laser-based bioprinting for fabrication of vascular tissue constructs. The review then provides the reader with the use of bioprinting for obtaining thick vascularized tissues using sacrificial bioink materials. Current challenges are discussed, a comparative evaluation of different bioprinting modalities is presented and future prospects are provided to the reader. Biofabrication of living tissues and organs at the clinically-relevant volumes vitally depends on the integration of vascular network. Despite the great progress in traditional biofabrication approaches, building perfusable hierarchical vascular network is a major challenge. Bioprinting is an emerging technology to fabricate design-specific tissue constructs due to its ability to create complex, heterocellular structures with anatomical precision

  15. HIV-1 evades virus-specific IgG2 and IgA responses by targeting systemic and intestinal B cells via long-range intercellular conduits.

    Science.gov (United States)

    Xu, Weifeng; Santini, Paul A; Sullivan, John S; He, Bing; Shan, Meimei; Ball, Susan C; Dyer, Wayne B; Ketas, Thomas J; Chadburn, Amy; Cohen-Gould, Leona; Knowles, Daniel M; Chiu, April; Sanders, Rogier W; Chen, Kang; Cerutti, Andrea

    2009-09-01

    Contact-dependent communication between immune cells generates protection but also facilitates viral spread. Here we found that macrophages formed long-range actin-propelled conduits in response to negative factor (Nef), a human immunodeficiency virus type 1 (HIV-1) protein with immunosuppressive functions. Conduits attenuated immunoglobulin G2 (IgG2) and IgA class switching in systemic and intestinal lymphoid follicles by shuttling Nef from infected macrophages to B cells through a guanine-exchange factor-dependent pathway involving the amino-terminal anchor, central core and carboxy-terminal flexible loop of Nef. By showing stronger virus-specific IgG2 and IgA responses in patients with Nef-deficient virions, our data suggest that HIV-1 exploits intercellular 'highways' as a 'Trojan horse' to deliver Nef to B cells and evade humoral immunity systemically and at mucosal sites of entry.

  16. DC performance and AC loss of cable-in-conduit conductors for International Thermonuclear Experimental Reactor

    National Research Council Canada - National Science Library

    Zhou, Wei; Fang, Xin-Yu; Fang, Jin; Liu, Bo

    2016-01-01

    ...) cable-in-conduit conductors(CICCs);however,the calculation of AC loss of ITER CICCs is a cumbersome task due to the complicated geometry of the multistage cables and the extreme operating conditions...

  17. Hydraulic tomography of discrete networks of conduits and fractures in a karstic aquifer by using a deterministic inversion algorithm

    Science.gov (United States)

    Fischer, P.; Jardani, A.; Lecoq, N.

    2018-02-01

    In this paper, we present a novel inverse modeling method called Discrete Network Deterministic Inversion (DNDI) for mapping the geometry and property of the discrete network of conduits and fractures in the karstified aquifers. The DNDI algorithm is based on a coupled discrete-continuum concept to simulate numerically water flows in a model and a deterministic optimization algorithm to invert a set of observed piezometric data recorded during multiple pumping tests. In this method, the model is partioned in subspaces piloted by a set of parameters (matrix transmissivity, and geometry and equivalent transmissivity of the conduits) that are considered as unknown. In this way, the deterministic optimization process can iteratively correct the geometry of the network and the values of the properties, until it converges to a global network geometry in a solution model able to reproduce the set of data. An uncertainty analysis of this result can be performed from the maps of posterior uncertainties on the network geometry or on the property values. This method has been successfully tested for three different theoretical and simplified study cases with hydraulic responses data generated from hypothetical karstic models with an increasing complexity of the network geometry, and of the matrix heterogeneity.

  18. Two cases of patients with renal transplants presenting with anuria due to an infarcted ileal conduit.

    Science.gov (United States)

    Coxon, Jonathan P; Jones, Chris R

    2002-10-01

    Transplanting kidneys into patients with an ileal conduit has become acceptable practice, and is usually well tolerated. We present the cases of two such patients who later presented as emergencies with anuria due to infarction of the ileal conduit. Both required operative intervention, and in both cases the renal function returned to its pre-operative level. The cases illustrate an important differential diagnosis of anuria in this group of transplant patients.

  19. Effects of dynamically variable saturation and matrix-conduit coupling of flow in karst aquifers

    Science.gov (United States)

    Reimann, T.; Geyer, T.; Shoemaker, W.B.; Liedl, R.; Sauter, M.

    2011-01-01

    Well-developed karst aquifers consist of highly conductive conduits and a relatively low permeability fractured and/or porous rock matrix and therefore behave as a dual-hydraulic system. Groundwater flow within highly permeable strata is rapid and transient and depends on local flow conditions, i.e., pressurized or nonpressurized flow. The characterization of karst aquifers is a necessary and challenging task because information about hydraulic and spatial conduit properties is poorly defined or unknown. To investigate karst aquifers, hydraulic stresses such as large recharge events can be simulated with hybrid (coupled discrete continuum) models. Since existing hybrid models are simplifications of the system dynamics, a new karst model (ModBraC) is presented that accounts for unsteady and nonuniform discrete flow in variably saturated conduits employing the Saint-Venant equations. Model performance tests indicate that ModBraC is able to simulate (1) unsteady and nonuniform flow in variably filled conduits, (2) draining and refilling of conduits with stable transition between free-surface and pressurized flow and correct storage representation, (3) water exchange between matrix and variably filled conduits, and (4) discharge routing through branched and intermeshed conduit networks. Subsequently, ModBraC is applied to an idealized catchment to investigate the significance of free-surface flow representation. A parameter study is conducted with two different initial conditions: (1) pressurized flow and (2) free-surface flow. If free-surface flow prevails, the systems is characterized by (1) a time lag for signal transmission, (2) a typical spring discharge pattern representing the transition from pressurized to free-surface flow, and (3) a reduced conduit-matrix interaction during free-surface flow. Copyright 2011 by the American Geophysical Union.

  20. Long distance seawater intrusion through a karst conduit network in the Woodville Karst Plain, Florida

    OpenAIRE

    Zexuan Xu; Seth Willis Bassett; Bill Hu; Scott Barrett Dyer

    2016-01-01

    Five periods of increased electrical conductivity have been found in the karst conduits supplying one of the largest first magnitude springs in Florida with water. Numerous well-developed conduit networks are distributed in the Woodville Karst Plain (WKP), Florida and connected to the Gulf of Mexico. A composite analysis of precipitation and electrical conductivity data provides strong evidence that the increases in conductivity are directly tied to seawater intrusion moving inland and travel...

  1. Ureteric catheterization via an ileal conduit: technique and retrieval of a JJ stent

    Energy Technology Data Exchange (ETDEWEB)

    Wah, T.M.; Kellett, M.J. E-mail: mjkellett@bigwig.net

    2004-11-01

    Retrograde ureteric catheterization of a patient with an ileal conduit is difficult, because guide wires and catheters coil in the conduit. A modified loopogram, using a Foley catheter as a fulcrum through which catheters can be advanced to the ureteric anastomosis, is described. This technique was used to remove a JJ stent, which had been inserted previously across a stricture in one ureter, the stent crossing from one kidney to the other.

  2. Efficient generation of smooth muscle cells from adipose-derived stromal cells by 3D mechanical stimulation can substitute the use of growth factors in vascular tissue engineering.

    Science.gov (United States)

    Parvizi, Mojtaba; Bolhuis-Versteeg, Lydia A M; Poot, André A; Harmsen, Martin C

    2016-07-01

    Occluding artery disease causes a high demand for bioartificial replacement vessels. We investigated the combined use of biodegradable and creep-free poly (1,3-trimethylene carbonate) (PTMC) with smooth muscle cells (SMC) derived by biochemical or mechanical stimulation of adipose tissue-derived stromal cells (ASC) to engineer bioartificial arteries. Biochemical induction of cultured ASC to SMC was done with TGF-β1 for 7d. Phenotype and function were assessed by qRT-PCR, immunodetection and collagen contraction assays. The influence of mechanical stimulation on non-differentiated and pre-differentiated ASC, loaded in porous tubular PTMC scaffolds, was assessed after culturing under pulsatile flow for 14d. Assays included qRT-PCR, production of extracellular matrix and scanning electron microscopy. ASC adhesion and TGF-β1-driven differentiation to contractile SMC on PTMC did not differ from tissue culture polystyrene controls. Mesenchymal and SMC markers were increased compared to controls. Interestingly, pre-differentiated ASC had only marginal higher contractility than controls. Moreover, in 3D PTMC scaffolds, mechanical stimulation yielded well-aligned ASC-derived SMC which deposited ECM. Under the same conditions, pre-differentiated ASC-derived SMC maintained their SMC phenotype. Our results show that mechanical stimulation can replace TGF-β1 pre-stimulation to generate SMC from ASC and that pre-differentiated ASC keep their SMC phenotype with increased expression of SMC markers. Copyright © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Conduits to care: call lights and patients’ perceptions of communication

    Directory of Open Access Journals (Sweden)

    Montie M

    2017-09-01

    Full Text Available Mary Montie,1 Clayton Shuman,1 Jose Galinato,1 Lance Patak,2 Christine A Anderson,1 Marita G Titler1 1Department of Systems, Populations, and Leadership, School of Nursing, University of Michigan, Ann Arbor, MI, 2Department of Anesthesiology and Pain Medicine, Seattle Children’s Hospital, Seattle, WA, USA Background: Call light systems remain the primary means of hospitalized patients to initiate communication with their health care providers. Although there is vast amounts of literature discussing patient communication with their health care providers, few studies have explored patients’ perceptions concerning call light use and communication. The specific aim of this study was to solicit patients’ perceptions regarding their call light use and communication with nursing staff. Methods: Patients invited to this study met the following inclusion criteria: proficient in English, been hospitalized for at least 24 hours, aged ≥21 years, and able to communicate verbally (eg, not intubated. Thirty participants provided written informed consent, were enrolled in the study, and completed interviews. Results: Using qualitative descriptive methods, five major themes emerged from patients’ perceptions (namely; establishing connectivity, participant safety concerns, no separation: health care and the call light device, issues with the current call light, and participants’ perceptions of “nurse work”. Multiple minor themes supported these major themes. Data analysis utilized the constant comparative methods of Glaser and Strauss. Discussion: Findings from this study extend the knowledge of patients’ understanding of not only why inconsistencies occur between the call light and their nurses, but also why the call light is more than merely a device to initiate communication; rather, it is a direct conduit to their health care and its delivery. Keywords: nurse–patient communication, medical technology, quality of care, qualitative research

  4. Current distribution in Cable-In-Conduit Conductors

    Energy Technology Data Exchange (ETDEWEB)

    Ferri, M.A.

    1994-05-01

    A numerical study of the current distribution in Cable-In-Conduit Conductors (CICC`s) experiencing linearly ramping transport currents and transverse magnetic fields was conducted for both infinitely long, periodic cables and finite length cables terminated in low resistance joints. The goal of the study was to gain insight into the phenomenon known as Ramp Rate Limitation, an as yet unexplained correspondence between maximum attainable current and the ramp time taken to reach that current in CICC superconducting magnets. A discrete geometric model of a 27 strand multiply twisted CICC was developed to effectively represent the flux linkages, mutual inductances, and resistive contact points between the strands of an experimentally tested cable. The results of the numerical study showed that for fully periodic cables, the current imbalances due to ramping magnetic fields and ramping transport currents are negligible in the range of experimentally explored operating conditions. For finite length, joint terminated cables, however, significant imbalances can exist. Unfortunately, quantitative results are limited by a lack of knowledge of the transverse resistance between strands in the joints. Nonetheless, general results are presented showing the dependency of the imbalance on cable length, ramp time, and joint resistance for both ramping transverse magnet fields and ramping transport currents. At the conclusion of the study, it is suggested that calculated current imbalances in a finite length cable could cause certain strands to prematurely ``quench`` -- become non-superconducting --thus leading to an instability for the entire cable. This numerically predicted ``current imbalance instability`` is compared to the experimentally observed Ramp Rate Limitation for the 27 strand CICC sample.

  5. Experimental constraints on degassing and permeability in volcanic conduit flow

    Science.gov (United States)

    Burgisser, Alain; Gardner, James E.

    2004-12-01

    This study assesses the effect of decompression rate on two processes that directly influence the behavior of volcanic eruptions: degassing and permeability in magmas. We studied the degassing of magma with experiments on hydrated natural rhyolitic glass at high pressure and temperature. From the data collected, we defined and characterized one degassing regime in equilibrium and two regimes in disequilibrium. Equilibrium bubble growth occurs when the decompression rate is slower than 0.1 MPa s-1, while higher rates cause porosity to deviate rapidly from equilibrium, defining the first disequilibrium regime of degassing. If the deviation is large enough, a critical threshold of super-saturation is reached and bubble growth accelerates, defining the second disequilibrium regime. We studied permeability and bubble coalescence in magma with experiments using the same rhyolitic melt in open degassing conditions. Under these open conditions, we observed that bubbles start to coalesce at ~43 vol% porosity, regardless of decompression rate. Coalescence profoundly affects bubble texture and size distributions, and induces the melt to become permeable. We determined coalescence to occur on a time scale (~180 s) independent of decompression rate. We parameterized and incorporated our experimental results into a 1D conduit flow model to explore the implications of our findings on eruptive behavior of rhyolitic melts with low crystal contents stored in the upper crust. Compared to previous models that assume equilibrium degassing of the melt during ascent, the introduction of disequilibrium degassing reduces the deviation from lithostatic pressure by ~25%, the acceleration at high porosities (>50 vol%) by a factor 5, and the associated decompression rate by an order of magnitude. The integration of the time scale of coalescence to the model shows that the transition between explosive and effusive eruptive regimes is sensitive to small variations of the initial magma ascent

  6. The Himalayas: barrier and conduit for gene flow.

    Science.gov (United States)

    Gayden, Tenzin; Perez, Annabel; Persad, Patrice J; Bukhari, Areej; Chennakrishnaiah, Shilpa; Simms, Tanya; Maloney, Trisha; Rodriguez, Kristina; Herrera, Rene J

    2013-06-01

    The Himalayan mountain range is strategically located at the crossroads of the major cultural centers in Asia, the Middle East and Europe. Although previous Y-chromosome studies indicate that the Himalayas served as a natural barrier for gene flow from the south to the Tibetan plateau, this region is believed to have played an important role as a corridor for human migrations between East and West Eurasia along the ancient Silk Road. To evaluate the effects of the Himalayan mountain range in shaping the maternal lineages of populations residing on either side of the cordillera, we analyzed mitochondrial DNA variation in 344 samples from three Nepalese collections (Newar, Kathmandu and Tamang) and a general population of Tibet. Our results revealed a predominantly East Asian-specific component in Tibet and Tamang, whereas Newar and Kathmandu are both characterized by a combination of East and South Central Asian lineages. Interestingly, Newar and Kathmandu harbor several deep-rooted Indian lineages, including M2, R5, and U2, whose coalescent times from this study (U2, >40 kya) and previous reports (M2 and R5, >50 kya) suggest that Nepal was inhabited during the initial peopling of South Central Asia. Comparisons with our previous Y-chromosome data indicate sex-biased migrations in Tamang and a founder effect and/or genetic drift in Tamang and Newar. Altogether, our results confirm that while the Himalayas acted as a geographic barrier for human movement from the Indian subcontinent to the Tibetan highland, it also served as a conduit for gene flow between Central and East Asia. Copyright © 2013 Wiley Periodicals, Inc.

  7. Novel flexible nerve conduits made of water-based biodegradable polyurethane for peripheral nerve regeneration.

    Science.gov (United States)

    Hsu, Shan-Hui; Chang, Wen-Chi; Yen, Chen-Tung

    2017-05-01

    Peripheral nerve conduits were fabricated from biodegradable polyurethane (PU) which was synthesized by a waterborne process. The biodegradable PU was based on poly(ε-caprolactone) diol and polyethylene butylene adipate diol (2:3 molar ratio) as the soft segment. Conduits formed by the freeze-drying process had asymmetric microporous structure. The PU nerve conduits were used to bridge a 10-mm gap in rat sciatic nerve. Nerve regeneration was evaluated by walking track analysis, magnetic resonance imaging (MRI), electrophysiological, and histological analyses. Results demonstrated that after 6 weeks, walking function was recovered by 40%. MR images showed that the transected nerve was reconnected after 3 weeks and the diameter of the regenerated nerve increased from 3 to 6 weeks. The nerve conduction velocity of the regenerated nerve reached 50% of the normal value after 6 weeks. Histological examination revealed that the cross-sectional area of the regenerated nerve at the midconduit was 0.24 mm2 after 6 weeks. The efficacy of PU nerve conduits based on functional recovery and histology was superior to that of commercial conduits (Neurotube). The PU nerve conduit developed in this study may be a potential candidate for clinical peripheral nerve tissue engineering. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 1383-1392, 2017. © 2017 Wiley Periodicals, Inc.

  8. Different conduits for the right ventricular outflow tract reconstruction in adults during the Ross procedure

    Directory of Open Access Journals (Sweden)

    А. М. Караськов

    2015-10-01

    Full Text Available We compared different conduits for the right ventricular outflow tract reconstruction (RVOT in adults during the Ross procedure. Between 1998 and 2012, 586 consecutive adult patients underwent the Ross procedures. Mean age was 45,514,2 years. The RVOT was reconstructed with a diepoxy-treated xenografts in 372 and with glutaraldehyde-treated in 88 patients. A pulmonary homograft was used in 125 patients. Hospital mortality was 4,9%. Mean follow up was 43,216,9 months. At discharge systolic gradient was 8,1 3,7 mm.Hg for the pulmonary homograft, 11,44,7 mm.Hg for the diepoxytreated and 14,96,1 mm.Hg for the glutaraldehyde-treated xenopericardial conduits. Twenty eight patients underwent reoperation. The 3-year actuarial freedom from conduit explantation for pulmonary homograft was 100%, for diepoxy- and glutaraldehyde-treated xenopericardial conduits 99,20,7% and 84,74,7% respectively. Multivariable analysis identified the type of xenograft and age as independent factors for xenograft dysfunction. Results from this study show that the pulmonary homograft is the most preferred conduit for the RVOT reconstruction during the Ross procedure. The diepoxy-treated xenopericardial conduits are acceptable alternative to the homograft in patients older 45 years.

  9. Tapering of xylem conduits and hydraulic limitations in sycamore (Acer pseudoplatanus) trees.

    Science.gov (United States)

    Petit, Giai; Anfodillo, Tommaso; Mencuccini, Maurizio

    2008-01-01

    Vertical conduit tapering is proposed as an effective mechanism to almost eliminate the increase in hydraulic resistance with increased height. Despite this potential role, very little is known about its changes during ontogeny. Here, conduit tapering and stem morphology of young/small and old/tall individuals of Acer pseudoplatanus in the field, as well as 3-yr-old grafted trees from both age classes, were analysed. The distribution of hydraulic resistance along stems was also determined in a subsample of trees. Substantial conduit tapering was found in small trees (field-grown and grafted from both age classes), whereas values were lower in tall trees, indicating that tapering was a size-related, not an age-related process. Apical conduit diameters were larger in tall trees and were inversely correlated with the degree of tapering. Hydraulic resistance increased less than linearly with distance from the apex. Its scaling against distance was indistinguishable from that predicted from anatomical measurements. Conduit tapering was an effective but partial mechanism of compensation for the increase in hydraulic resistance with tree height. Size-related changes in tapering and in apical conduit diameters may be explained by the combined need to reduce the build-up of hydraulic resistance while minimizing the carbon costs of building vessel walls.

  10. Comparison of a karst groundwater model with and without discrete conduit flow

    Science.gov (United States)

    Saller, Stephen P.; Ronayne, Michael J.; Long, Andrew J.

    2013-01-01

    Karst aquifers exhibit a dual flow system characterized by interacting conduit and matrix domains. This study evaluated the coupled continuum pipe-flow framework for modeling karst groundwater flow in the Madison aquifer of western South Dakota (USA). Coupled conduit and matrix flow was simulated within a regional finite-difference model over a 10-year transient period. An existing equivalent porous medium (EPM) model was modified to include major conduit networks whose locations were constrained by dye-tracing data and environmental tracer analysis. Model calibration data included measured hydraulic heads at observation wells and estimates of discharge at four karst springs. Relative to the EPM model, the match to observation well hydraulic heads was substantially improved with the addition of conduits. The inclusion of conduit flow allowed for a simpler hydraulic conductivity distribution in the matrix continuum. Two of the high-conductivity zones in the EPM model, which were required to indirectly simulate the effects of conduits, were eliminated from the new model. This work demonstrates the utility of the coupled continuum pipe-flow method and illustrates how karst aquifer model parameterization is dependent on the physical processes that are simulated.

  11. Collagen vascular disease

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/001223.htm Collagen vascular disease To use the sharing features on this page, ... previously said to have "connective tissue" or "collagen vascular" disease. We now have names for many specific conditions ...

  12. Oscillation of Angiogenesis and Vascular Dropout in Progressive Human Vascular Disease. [Vascular Pattern as Useful Read-Out of Complex Molecular Signaling

    Science.gov (United States)

    Parsons-Wingerter, Patricia

    2010-01-01

    When analyzed by VESsel GENeration Analysis (VESGEN) software, vascular patterns provide useful integrative read-outs of complex, interacting molecular signaling pathways. Using VESGEN, we recently discovered and published our innovative, surprising findings that angiogenesis oscillated with vascular dropout throughout progression of diabetic retinopathy, a blinding vascular disease. Our findings provide a potential paradigm shift in the current prevailing view on progression and treatment of this disease, and a new early-stage window of regenerative therapeutic opportunities. The findings also suggest that angiogenesis may oscillate with vascular disease in a homeostatic-like manner during early stages of other inflammatory progressive diseases such as cancer and coronary vascular disease.

  13. Use new PLGL-RGD-NGF nerve conduits for promoting peripheral nerve regeneration

    Directory of Open Access Journals (Sweden)

    Yan Qiongjiao

    2012-07-01

    Full Text Available Abstract Background Nerve conduits provide a promising strategy for peripheral nerve injury repair. However, the efficiency of nerve conduits to enhance nerve regeneration and functional recovery is often inferior to that of autografts. Nerve conduits require additional factors such as cell adhesion molecules and neurotrophic factors to provide a more conducive microenvironment for nerve regeneration. Methods In the present study, poly{(lactic acid-co-[(glycolic acid-alt-(L-lysine]} (PLGL was modified by grafting Gly-Arg-Gly-Asp-Gly (RGD peptide and nerve growth factor (NGF for fabricating new PLGL-RGD-NGF nerve conduits to promote nerve regeneration and functional recovery. PLGL-RGD-NGF nerve conduits were tested in the rat sciatic nerve transection model. Rat sciatic nerves were cut off to form a 10 mm defect and repaired with the nerve conduits. All of the 32 Wistar rats were randomly divided into 4 groups: group PLGL-RGD-NGF, group PLGL-RGD, group PLGL and group autograft. At 3 months after surgery, the regenerated rat sciatic nerve was evaluated by footprint analysis, electrophysiology, and histologic assessment. Experimental data were processed using the statistical software SPSS 10.0. Results The sciatic function index value of groups PLGL-RGD-NGF and autograft was significantly higher than those of groups PLGL-RGD and PLGL. The nerve conduction velocities of groups PLGL-RGD-NGF and autograft were significantly faster than those of groups PLGL-RGD and PLGL. The regenerated nerves of groups PLGL-RGD-NGF and autograft were more mature than those of groups PLGL-RGD and PLGL. There was no significant difference between groups PLGL-RGD-NGF and autograft. Conclusions PLGL-RGD-NGF nerve conduits are more effective in regenerating nerves than both PLGL-RGD nerve conduits and PLGL nerve conduits. The effect is as good as that of an autograft. This work established the platform for further development of the use of PLGL-RGD-NGF nerve conduits for

  14. Characteristics and biocompatibility of a biodegradable genipin-cross-linked gelatin/β-tricalcium phosphate reinforced nerve guide conduit.

    Science.gov (United States)

    Yang, Yi-Chin; Shen, Chiung-Chyi; Huang, Tsung-Bin; Chang, Shun-Hsung; Cheng, Hsu-Chen; Liu, Bai-Shuan

    2010-10-01

    To modulate the mechanical properties of nerve guide conduit for surgical manipulation, this study develops a biodegradable composite containing genipin cross-linked gelatin annexed with β-tricalcium phosphate ceramic particles as a nerve guide material. The conduit was dark bluish and round with a rough and compact outer surface compared to the genipin cross-linked gelatin conduit (without β-tricalcium phosphate). Water uptake and swelling tests indicate that the conduit noticeably increases the stability in water, and the hydrated conduit does not collapse and stenose. The conduit has a sufficiently high level of mechanical properties to serve as a nerve guide. After subcutaneous implantation on the dorsal side of a rat, the degraded conduit only evokes a mild tissue response, and the formation of a very thin fibrous capsule surrounds the conduit. This paper assesses the effectiveness of the conduit as a guidance channel when we use it to repair a 10 mm gap in the rat's sciatic nerve. The experimental results show no gross inflammatory reactions of the peripheral nerve tissues at the implantation site in either group. In overall gross examination, the diameter of the intratubular and newly formed nerve fibers in the conduits exceeds that of the silicone tubes during the implantation period. The quantitative results indicate the superiority of the conduits over the silicone tubes. This study microscopically observes the nerve regeneration in the tissue section at the middle region of all implanted conduits. Therefore, the histomorphometric assessment demonstrates that the conduit could be a candidate for peripheral nerve repair.

  15. Decellularized ureter for tissue-engineered small-caliber vascular graft.

    Science.gov (United States)

    Narita, Yuji; Kagami, Hideaki; Matsunuma, Hiroshi; Murase, Yosuke; Ueda, Minoru; Ueda, Yuichi

    2008-01-01

    Previous attempts to create small-caliber vascular prostheses have been limited. The aim of this study was to generate tissue-engineered small-diameter vascular grafts using decellularized ureters (DUs). Canine ureters were decellularized using one of four different chemical agents [Triton-X 100 (Tx), deoxycholate (DCA), trypsin, or sodium dodecyl sulfate (SDS)] and the histology, residual DNA contents, and immunogenicity of the resulting DUs were compared. The mechanical properties of the DUs were evaluated in terms of water permeability, burst strength, tensile strength, and compliance. Cultured canine endothelial cells (ECs) and myofibroblasts were seeded onto DUs and evaluated histologically. Canine carotid arteries were replaced with the EC-seeded DUs (n = 4). As controls, nonseeded DUs (n = 5) and PTFE prostheses (n = 4) were also used to replace carotid arteries. The degree of decellularization and the maintenance of the matrix were best in the Tx-treated DUs. Tx-treated and DCA-treated DUs had lower remnant DNA contents and immunogenicity than the others. The burst strength of the DUs was more than 500 mmHg and the maximum tensile strength of the DUs was not different to that of native ureters. DU compliance was similar to that of native carotid artery. The cell seeding test resulted in monolayered ECs and multilayered alpha-smooth muscle actin-positive cells on the DUs. The animal implantation model showed that the EC-seeded DUs were patent for at least 6 months after the operation, whereas the nonseeded DUs and PTFE grafts become occluded within a week. These results suggest that tissue-engineered DUs may be a potential alternative conduit for bypass surgery.

  16. Nox, Reactive Oxygen Species and Regulation of Vascular Cell Fate

    Directory of Open Access Journals (Sweden)

    Denise Burtenshaw

    2017-11-01

    Full Text Available The generation of reactive oxygen species (ROS and an imbalance of antioxidant defence mechanisms can result in oxidative stress. Several pro-atherogenic stimuli that promote intimal-medial thickening (IMT and early arteriosclerotic disease progression share oxidative stress as a common regulatory pathway dictating vascular cell fate. The major source of ROS generated within the vascular system is the nicotinamide adenine dinucleotide phosphate (NADPH oxidase family of enzymes (Nox, of which seven members have been characterized. The Nox family are critical determinants of the redox state within the vessel wall that dictate, in part the pathophysiology of several vascular phenotypes. This review highlights the putative role of ROS in controlling vascular fate by promoting endothelial dysfunction, altering vascular smooth muscle phenotype and dictating resident vascular stem cell fate, all of which contribute to intimal medial thickening and vascular disease progression.

  17. Variable-density numerical modeling of seawater intrusion in coastal aquifer with well-developed conduits

    Science.gov (United States)

    Xu, Z.; Hu, B. X.

    2015-12-01

    Karst aquifer is an important drinking water supply for nearly 25% of the world's population. Well-developed subground conduit systems usually can be found in a well-developed karst aquifer, as a dual permeability system. Hydraulic characteristics of non-laminar flow in conduits could be significantly different from darcian flow in porous medium; therefore, hybrid model and different governing equations are necessary in numerical modeling of karst hydrogeology. On the other hand, seawater intrusion has been observed and studied for several decades, also become a worldwidely problem due to groundwater over-pumping and rising sea level. The density difference between freshwater and seawater is recognized as the major factor governing the movements of two fluids in coastal aquifer. Several models have been developed to simulate groundwater flow in karst aquifer, but hardly describe seawater intrusion through the conduits without coupling variable density flow and solute transport. In this study, a numerical SEAWAT model has been developed to simulate variable density flow and transport in heterogeneous karst aquifer. High-density seawater is verified to intrude further inland through high permeability conduit network rather than porous medium. The numerical model also predicts the effect of different cases on seawater intrusion in coastal karst aquifer, such as rising sea level, tide stages and freshwater discharge effects. A series of local and global uncertainty analysis have been taken to evaluate the sensitivity of hydraulic conductivity, porosity, groundwater pumping, sea level, salinity and dispersivity. Heterogeneous conduit and porous medium hydraulic characteristics play an important role in groundwater flow and solute transport simulation. Meanwhile, another hybrid model VDFST-CFP model is currently under development to couple turbulent conduit flow and variable density groundwater flow in porous media, which provides a new method and better description in

  18. Does a third arterial conduit to the right coronary circulation improve survival?

    Science.gov (United States)

    Luthra, Suvitesh; Leiva-Juárez, Miguel M; Matuszewski, Maciej; Morgan, Ian S; Billing, John S

    2018-03-01

    The long-term benefits of a third arterial conduit to the right circulation in triple-vessel disease remain debatable. This retrospective, single-center, propensity-matched study investigates the impact of a third arterial conduit to the right circulation on early and intermediate survival after coronary artery bypass grafting. Data were retrospectively collected from 2004 to 2014 for all surgical revascularizations for triple-vessel disease with at least 2 arterial conduits to the left circulation and a third arterial or venous conduit to the right circulation. A total of 167 pairs were propensity matched to arterial versus venous third conduit to right circulation. Hazard functions were obtained with Cox multivariate regression and Kaplan-Meier survival curves were compared between the matched cohorts. Extracardiac arteriopathy, logistic euroSCORE, and left main stem disease were significant predictors of adverse survival. A third arterial conduit to the right circulation was not a significant predictor of improved survival in multivariate analysis (HR, 0.72; 95% CI, 0.34-1.55; P = .411). 30-day mortality was 0.6% in both groups. There was no significant difference in early or intermediate survival in the propensity-matched groups (venous vs arterial, 99.2% vs 99.2%; P = 1.000 at 1 year; 85.2% vs 88.8%; P = .248 at 5 years and 69.2% vs 88.8%; P = .297 at 7 years) CONCLUSIONS: The use of a third arterial versus a venous conduit to the right circulation does not improve early or intermediate survival up to 7 years in triple-vessel coronary artery disease in this study. Longer follow-up and larger cohorts may be needed for differences to emerge. Copyright © 2017 The American Association for Thoracic Surgery. All rights reserved.

  19. Fabrication and Optimization of Gelatin/ Nano Bioglass Conduits for Peripheral Nerve Regeneration

    Directory of Open Access Journals (Sweden)

    M. Foroutan Koudehi

    2014-07-01

    Full Text Available Introduction & Objective: Peripheral nerve injury is common in trauma patients and 4.5% of all soft-tissue injuries are accompanied by defects of peripheral nerve. Peripheral nerve injuries can lead to lifetime loss of function and permanent disfigurement. Designed conduits com-prised of natural and synthetic materials are now widely used in the construction of damaged tissues. The aim of this project was to prepare nanocomposite conduits from gelatin and bioglass for damaged peripheral nerve reconstruction. Materials & Methods: In this experimental study,compound water solution of gelatin and nano bioglass synthesized through sol gel method, was made. After preparing the solution, special mandrels were dipped in solution several times and freeze dried in order to be emptied of wa-ter via sublimation. The conduits had the following dimensions: internal diameter: 1.6 mm, outside diameter: 2.2 mm and length about 12 mm. In order to evaluate the biocompatibility of conduits we used cytotoxicity test by Chinese ovary cells and MTT assay by Miapaca-2 (pancreatic cancer cell line. Results: The prepared nano bioglass and conduits were characterized using transmission elec-tron microscopy, scanning electron microscopy, fourier transformed infrared spectroscopy and X-ray diffraction. Results of biocompatibility test showed no sign of cytotoxicity and cells were found to be attached to the pore walls offered by the conduits. Conclusion: According to the results, nano bioglass conduits could be a good candidate for peripheral nerve regeneration. (Sci J Hamadan Univ Med Sci 2014; 21 (2:152-160

  20. Evolution of karst conduit networks in transition from pressurised flow to free surface flow

    Science.gov (United States)

    Perne, M.; Covington, M. D.; Gabrovšek, F.

    2014-06-01

    We present a novel modelling approach to study the evolution of conduit networks in soluble rocks. Unlike the models presented so far, the model allows a transition from pressurised (pipe) flow to a free surface (open channel) flow in evolving discrete conduit networks. It calculates flow, solute transport and dissolutional enlargement within each time step and steps through time until a stable flow pattern establishes. The flow in each time step is calculated by calling the EPA Storm Water Management Model (EPA SWMM), which efficiently solves the 1-D Saint Venant equations in a network of conduits. We present several cases with low dip and sub-vertical networks to demonstrate mechanisms of flow pathway selection. In low dip models the inputs were randomly distributed to several junctions. The evolution of pathways progresses upstream: initially pathways linking outlets to the closest inputs evolve fastest because the gradient along these pathways is largest. When a pathway efficiently drains the available recharge, the head drop along the pathway attracts flow from the neighbouring upstream junctions and new connecting pathways evolve. The mechanism progresses from the output boundary inwards until all inputs are connected to the stable flow system. In the pressurised phase, each junction is drained by at least one conduit, but only one conduit remains active in the vadose phase. The selection depends on the initial geometry of a junction, initial distribution of diameters, the evolution in a pressurised regime, and on the dip of the conduits, which plays an important role in vadose entrenchment. In high dip networks, the vadose zone propagates downwards and inwards from the rim of the massif. When a network with randomly distributed initial diameters is supplied with concentrated recharge from the adjacent area, the sink point regresses up upstream along junctions connected to the prominent pathways. Large conductive structures provide deep penetration of high

  1. Generator. Generator

    Energy Technology Data Exchange (ETDEWEB)

    Knoedler, R.; Bossmann, H.P.

    1992-03-12

    The invention refers to a thermo-electric generator, whose main part is a sodium concentration cell. In conventional thermo-electric generators of this kind, the sodium moving from a hot space to a colder space must be transported back to the hot space via a circulation pipe and a pump. The purpose of the invention is to avoid the disadvantages of this return transport. According to the invention, the thermo-electric generator is supported so that it can rotate, so that the position of each space relative to its propinquity to the heat source can be changed at any time.

  2. Cavitation Resistance in Seedless Vascular Plants: The Structure and Function of Interconduit Pit Membranes1[W][OPEN

    Science.gov (United States)

    Brodersen, Craig; Jansen, Steven; Choat, Brendan; Rico, Christopher; Pittermann, Jarmila

    2014-01-01

    Plant water transport occurs through interconnected xylem conduits that are separated by partially digested regions in the cell wall known as pit membranes. These structures have a dual function. Their porous construction facilitates water movement between conduits while limiting the spread of air that may enter the conduits and render them dysfunctional during a drought. Pit membranes have been well studied in woody plants, but very little is known about their function in more ancient lineages such as seedless vascular plants. Here, we examine the relationships between conduit air seeding, pit hydraulic resistance, and pit anatomy in 10 species of ferns (pteridophytes) and two lycophytes. Air seeding pressures ranged from 0.8 ± 0.15 MPa (mean ± sd) in the hydric fern Athyrium filix-femina to 4.9 ± 0.94 MPa in Psilotum nudum, an epiphytic species. Notably, a positive correlation was found between conduit pit area and vulnerability to air seeding, suggesting that the rare-pit hypothesis explains air seeding in early-diverging lineages much as it does in many angiosperms. Pit area resistance was variable but averaged 54.6 MPa s m−1 across all surveyed pteridophytes. End walls contributed 52% to the overall transport resistance, similar to the 56% in angiosperm vessels and 64% in conifer tracheids. Taken together, our data imply that, irrespective of phylogenetic placement, selection acted on transport efficiency in seedless vascular plants and woody plants in equal measure by compensating for shorter conduits in tracheid-bearing plants with more permeable pit membranes. PMID:24777347

  3. Evaluation of Arching Action Generated in the Backfill between Outlet Conduit and Existing Embankment

    National Research Council Canada - National Science Library

    KOBAYASHI, Noriyuki; MOCHIDA, Junya; SUMIDA, Yutaro; YOSHITAKE, Yoshitaka

    2012-01-01

    .... This phenomenon is called arching action and causes a large reduction of stress. Consequently, the backfill under the arch becomes a weak point in the structure and poses a risk of hydraulic fracturing...

  4. Platelet-derived growth factor B retention is essential for development of normal structure and function of conduit vessels and capillaries

    DEFF Research Database (Denmark)

    Nyström, Henrik C.; Lindblom, Per; Wickman, Anna

    2006-01-01

    : Passive and active properties of conduit vessels were studied using myograph techniques and histological examination. Capillary structure and function was studied using measurements of capillary density in skeletal muscle and by assessing aerobic physical performance in a treadmill setup. Cardiac function...... was assessed using echocardiography. RESULTS: Myograph experiments revealed an increased diameter and stiffness of the aorta in RetKO. Histological examination showed increased media collagen content and a decreased number of aortic wall layers, however with a similar number of vascular smooth muscle cells....... This outward eutrophic remodelling of the aorta was accompanied by endothelial dysfunction. RetKO showed decreased capillary density in skeletal muscle and signs of a defective delivery of capillary oxygen to skeletal muscle, as shown by a decreased physical performance. In RetKO mice, echocardiography...

  5. Electrospun Polycaprolactone/Polylactic Acid Nanofibers as an Artificial Nerve Conduit

    Directory of Open Access Journals (Sweden)

    Zeeshan Ali Khatri

    2014-07-01

    Full Text Available Development of conduits made of biodegradable nanofibers is gaining substantial interest due to their suitability for nerve regeneration. Among all polymeric nanofibers PCL (Poly ?-Caprolactone is distinctively found for mechanical stability and PLLA (Poly (L-Lactic Acid for relatively faster biodegradability. The aim of this study is to investigate blending compatibility between PCL and PLLA and the ability to fabricate nanofibers conduits via electro spinning. The PCL-PLLA nano-fiber tubular made from different blend ratios of PCL-PLLA were electro spun. The electro spun nanofibers were continuously deposited over high speed rotating mandrel to fabricate nanofibers conduit having inner diameter of 2mm and the wall thickness of 55-65µm. The diameters of nano-fibers were between 715-860nm. FTIR (Fourier Transform Infrared spectroscopy used to analyze chemical change in the blends of nerve conduits, which revealed that the PCL-PLLA blend nanofiber exhibit characteristic peaks of both PCL and PLLA and was composition dependent. The crystallinity of PCL-PLLA tubes were studied using WAXD (Wide Angle Xray Diffraction. The morphology of nanofibers were investigated under SEM (Scanning Electron Microscope. The mechanical properties of the conduits were also tested; the Young?s modulus obtained for small diameter was 10MPa, twice as high as larger diameter.

  6. Effects of nerve cells and adhesion molecules on nerve conduit for peripheral nerve regeneration.

    Science.gov (United States)

    Chung, Joo-Ryun; Choi, Jong-Won; Fiorellini, Joseph P; Hwang, Kyung-Gyun; Park, Chang-Joo

    2017-09-01

    For peripheral nerve regeneration, recent attentions have been paid to the nerve conduits made by tissue-engineering technique. Three major elements of tissue-engineering are cells, molecules, and scaffolds. In this study, the attachments of nerve cells, including Schwann cells, on the nerve conduit and the effects of both growth factor and adhesion molecule on these attachments were investigated. The attachment of rapidly-proliferating cells, C6 cells and HS683 cells, on nerve conduit was better than that of slowly-proliferating cells, PC12 cells and Schwann cells, however, the treatment of nerve growth factor improved the attachment of slowly-proliferating cells. In addition, the attachment of Schwann cells on nerve conduit coated with fibronectin was as good as that of Schwann cells treated with glial cell line-derived neurotrophic factor (GDNF). Growth factor changes nerve cell morphology and affects cell cycle time. And nerve growth factor or fibronectin treatment is indispensable for Schwann cell to be used for implantation in artificial nerve conduits.

  7. A novel electrospun nerve conduit enhanced by carbon nanotubes for peripheral nerve regeneration

    Science.gov (United States)

    Yu, Wenwen; Jiang, Xinquan; Cai, Ming; Zhao, Wen; Ye, Dongxia; Zhou, Yong; Zhu, Chao; Zhang, Xiuli; Lu, Xiaofeng; Zhang, Zhiyuan

    2014-04-01

    For artificial nerve conduits, great improvements have been achieved in mimicking the structures and components of autologous nerves. However, there are still some problems in conduit construction, especially in terms of mechanical properties, biomimetic surface tomography, electrical conductivity and sustained release of neurotrophic factors or cells. In this study, we designed and fabricated a novel electrospun nerve conduit enhanced by multi-walled carbon nanotubes (MWNTs) on the basis of a collagen/poly(ɛ-caprolactone) (collagen/PCL) fibrous scaffold. Our aim was to provide further knowledge about the mechanical effects and efficacy of MWNTs on nerve conduits as well as the biocompatibility and toxicology of MWNTs when applied in vivo. The results showed that as one component, carboxyl MWNTs could greatly alter the composite scaffold’s hydrophilicity, mechanical properties and degradability. The electrospun fibers enhanced by MWNTs could support Schwann cell adhesion and elongation as a substrate in vitro. In vivo animal studies demonstrated that the MWNT-enhanced collagen/PCL conduit could effectively promote nerve regeneration of sciatic nerve defect in rats and prevent muscle atrophy without invoking body rejection or serious chronic inflammation. All of these results showed that this MWNT-enhanced scaffold possesses good biocompatibility and MWNTs might be excellent candidates as engineered nanocarriers for further neurotrophic factor delivery research.

  8. Vegetable cells in urinary samples of patients with bricker ileal conduit.

    Science.gov (United States)

    Planinšek, Tanja; Kladnik, Aleš; Pohar-Marinšek, Ziva; Fležar, Margareta Strojan

    2014-02-01

    During routine cytopathological evaluation of urines for malignant cells we have occasionally noticed vegetable cells that were only present in patients with Bricker ileal conduit. We wanted to identify the means and sources of contamination of urinary samples from these patients. During the period between May and November 2010, 637 urinary samples were routinely evaluated for malignant cells. Among them were 13 urinary samples from Bricker ileal conduit which we rescreened. We prepared all urinary samples by membrane filtration and stained them according to Papanicolaou. Subsequently, we prepared samples from ostomy adhesives made by Coloplast and by ConvaTec which are used to secure the ostomy bag onto urostomy. We also took samples from different constituents (hydrocolloids) of ostomy adhesives. On the cytopathological review, we found vegetable cells along with intestinal mucosa cells in urinary samples of seven patients with Bricker ileal conduit. With the light microscopic examination of the samples prepared from different ostomy adhesives, we found vegetable cells only in Coloplast adhesives. In preparations of hydrocolloids, we found vegetable cells only in guar gum. They were morphologically identical to those found in urine samples of patients with Bricker ileal conduit and in Sensura and Sensura Xpro (Coloplast) ostomy adhesives. We determined that the origin of vegetable cells in urines from Bricker ileal conduit is the ostomy adhesive. The vegetable cells differ from human intestinal epithelial cells regarding size, shape, and color so it is difficult to misinterpret them as dysplastic cells. Copyright © 2013 Wiley Periodicals, Inc.

  9. Bricker's ileal conduit urinary diversion with a simple non-refluxing uretero ileal anastomosis

    DEFF Research Database (Denmark)

    Bernstein, I T; Bennicke, K; Rørdam, P

    1991-01-01

    Fifty consecutive patients had ileal conduits constructed with a technically and quick simple antireflux ureteroileal anastomosis. Complications related to the ureteral implantation were studied retrospectively, and at follow-up (8 months-12 years later, median 3 years) conduit dysfunction and ur...... from 300 to 420 mumol/l. Partial ureteral reflux was present in three (2 patients) of 33 ureters studied and minimal conduit dysfunction was found in 8 patients. In conclusion we find this method of urinary diversion to be quick, easy, and safe.......Fifty consecutive patients had ileal conduits constructed with a technically and quick simple antireflux ureteroileal anastomosis. Complications related to the ureteral implantation were studied retrospectively, and at follow-up (8 months-12 years later, median 3 years) conduit dysfunction...... and ureteral reflux were assessed in 18 patients out of the 25 patients who were still alive. Early complications and signs of late upper urinary tract deterioration were similar to those found after other operative techniques had been used. One patient had a postoperative urinary leak from the uretero ileal...

  10. Mechanisms of Glioma Formation: Iterative Perivascular Glioma Growth and Invasion Leads to Tumor Progression, VEGF-Independent Vascularization, and Resistance to Antiangiogenic Therapy

    Directory of Open Access Journals (Sweden)

    Gregory J. Baker

    2014-07-01

    Full Text Available As glioma cells infiltrate the brain they become associated with various microanatomic brain structures such as blood vessels, white matter tracts, and brain parenchyma. How these distinct invasion patterns coordinate tumor growth and influence clinical outcomes remain poorly understood. We have investigated how perivascular growth affects glioma growth patterning and response to antiangiogenic therapy within the highly vascularized brain. Orthotopically implanted rodent and human glioma cells are shown to commonly invade and proliferate within brain perivascular space. This form of brain tumor growth and invasion is also shown to characterize de novo generated endogenous mouse brain tumors, biopsies of primary human glioblastoma (GBM, and peripheral cancer metastasis to the human brain. Perivascularly invading brain tumors become vascularized by normal brain microvessels as individual glioma cells use perivascular space as a conduit for tumor invasion. Agent-based computational modeling recapitulated biological perivascular glioma growth without the need for neoangiogenesis. We tested the requirement for neoangiogenesis in perivascular glioma by treating animals with angiogenesis inhibitors bevacizumab and DC101. These inhibitors induced the expected vessel normalization, yet failed to reduce tumor growth or improve survival of mice bearing orthotopic or endogenous gliomas while exacerbating brain tumor invasion. Our results provide compelling experimental evidence in support of the recently described failure of clinically used antiangiogenics to extend the overall survival of human GBM patients.

  11. Methane dynamics in Northern Wetlands: Significance of vascular plants

    Energy Technology Data Exchange (ETDEWEB)

    Joabsson, Anna

    2001-09-01

    The studies presented illustrate several different aspects of the impact of vascular plants on methane emissions from northern natural wetlands. The subject has been approached on different scales, ranging from the study of microbial substrates in the vicinity of a single plant root, to an attempt to extrapolate some of the results to the entire northern hemisphere north of 50 meridian. The main overall conclusions from the papers are that vascular plants affect net methane emissions 1) by offering an efficient route of transport to the atmosphere so that methane oxidation in oxic surface soils is avoided, and 2) by being sources of methanogenic substrate. The degree to which vascular wetland plants affect methane emissions seems to be dependent on species-specific differences in both the capacity to act as gas conduits and the exudation of labile carbon compounds to the soil. An intimate coupling between vascular plant production and methane emission was found in an Arctic tundra wetland, although other environmental variables (water table, temperature) also contributed significantly to the explained variation in methane exchange. Studies of vascular plant extidation of organic acids suggest that the available pool of methanogenic substrates is both qualitatively and quantitatively correlated to vascular plant production (photosynthetic rate). On global scales, vascular plant production as a single factor does not seem to be sufficient to explain the majority of variation in methane flux patterns. Based on comparable experiments at five different sites in the northwestern Eurasian and Greenlandic North, we suggest that mean seasonal soil temperature is the best predictor of methane exchange on broad spatial and temporal scales.

  12. Generator. Generator

    Energy Technology Data Exchange (ETDEWEB)

    Bossmann, H.P.; Knoedler, R.

    1992-03-12

    The invention refers to a thermo-electric generator, which contains sodium as the means of heat transport. The sodium moves from the space of higher temperature through a space into the space of lower temperature. One can do without a pump for transporting the sodium back from the space of lower temperature to the space of higher temperature, as the thermo-electric generator can rotate around an axis. It is therefore possible to interchange the position of the two spaces relative to the heat source.

  13. Vascular grading of angiogenesis

    DEFF Research Database (Denmark)

    Hansen, S; Grabau, D A; Sørensen, Flemming Brandt

    2000-01-01

    The study aimed to evaluate the prognostic value of angiogenesis by vascular grading of primary breast tumours, and to evaluate the prognostic impact of adding the vascular grade to the Nottingham Prognostic Index (NPI). The investigation included 836 patients. The median follow-up time was 11...... years and 4 months. The microvessels were immunohistochemically stained by antibodies against CD34. Angiogenesis was graded semiquantitatively by subjective scoring into three groups according to the expected number of microvessels in the most vascular tumour area. The vascular grading between observers...... was moderately reproduced (kappa = 0.59). Vascular grade was significantly associated with axillary node involvement, tumour size, malignancy grade, oestrogen receptor status and histological type. In univariate analyses vascular grade significantly predicted recurrence free survival and overall survival for all...

  14. Biodegradable conduit small gap tubulization for peripheral nerve mutilation: a substitute for traditional epineurial neurorrhaphy.

    Science.gov (United States)

    Zhang, Peixun; Han, Na; Wang, Tianbing; Xue, Feng; Kou, Yuhui; Wang, Yanhua; Yin, Xiaofeng; Lu, Laijin; Tian, Guanglei; Gong, Xu; Chen, Shanlin; Dang, Yu; Peng, Jianping; Jiang, Baoguo

    2013-01-01

    Nerve regeneration and re-innervation are usually difficult after peripheral nerve injury. Epineurium neurorrhaphy to recover the nerve continuity is the traditional choice of peripheral nerve mutilation without nerve defects, whereas the functional recovery remains quite unsatisfactory. Based on previous research in SD rats and Rhesus Monkeys, a multiple centers clinical trial about biodegradable conduit small gap tubulization for peripheral nerve mutilation to substitute traditional epineurial neurorrhaphy was carried out. Herein, the authors reviewed the literature that focused on peripheral nerve injury and possible clinical application, and confirmed the clinical possibilities of biodegradable conduit small gap tubulization to substitute traditional epineurial neurorrhaphy for peripheral nerve mutilation. The biodegradable conduit small gap tubulization to substitute traditional epineurial neurorrhaphy for peripheral nerve mutilation may be a revolutionary innovation in peripheral nerve injury and repair field.

  15. The Use of Degradable Nerve Conduits for Human Nerve Repair: A Review of the Literature

    Directory of Open Access Journals (Sweden)

    M. F. Meek

    2005-01-01

    Full Text Available The management of peripheral nerve injury continues to be a major clinical challenge. The most widely used technique for bridging defects in peripheral nerves is the use of autologous nerve grafts. This technique, however, has some disadvantages. Many alternative experimental techniques have thus been developed, such as degradable nerve conduits. Degradable nerve guides have been extensively studied in animal experimental studies. However, the repair of human nerves by degradable nerve conduits has been limited to only a few clinical studies. In this paper, an overview of the available international published literature on degradable nerve conduits for bridging human peripheral nerve defects is presented for literature available until 2004. Also, the philosophy on the use of nerve guides and nerve grafts is given.

  16. Uterine vascular lesions.

    Science.gov (United States)

    Vijayakumar, Abhishek; Srinivas, Amruthashree; Chandrashekar, Babitha Moogali; Vijayakumar, Avinash

    2013-01-01

    Vascular lesions of the uterus are rare; most reported in the literature are arteriovenous malformations (AVMs). Uterine AVMs can be congenital or acquired. In recent years, there has been an increasing number of reports of acquired vascular lesions of the uterus following pregnancy, abortion, cesarean delivery, and curettage. It can be seen from these reports that there is confusion concerning the terminology of uterine vascular lesions. There is also a lack of diagnostic criteria and management guidelines, which has led to an increased number of unnecessary invasive procedures (eg, angiography, uterine artery embolization, hysterectomy for abnormal vaginal bleeding). This article familiarizes readers with various vascular lesions of the uterus and their management.

  17. Vascular biology of preeclampsia.

    Science.gov (United States)

    Myatt, L; Webster, R P

    2009-03-01

    Preeclampsia, a pregnancy-specific syndrome characterized by hypertension, proteinuria and edema, resolves on delivery of the placenta. Normal pregnancy is itself characterized by systemic inflammation, oxidative stress and alterations in levels of angiogenic factors and vascular reactivity. This is exacerbated in preeclampsia with an associated breakdown of compensatory mechanisms, eventually leading to placental and vascular dysfunction. The underlying pathology of preeclampsia is thought to be a relatively hypoxic or ischemic placenta. Both the placenta and maternal vasculatures are major sources of reactive oxygen and nitrogen species which can interact to produce peroxynitrite a powerful prooxidant that covalently modifies proteins by nitration of tyrosine residues, to possibly alter vascular function in preeclampsia. The linkage between placental hypoxia and maternal vascular dysfunction has been proposed to be via placental syncytiotrophoblast basement membranes shed by the placenta or via angiogenic factors which include soluble flt1 and endoglin secreted by the placenta that bind vascular endothelial growth factor (VEGF) and placental growth factor (PIGF) in the maternal circulation. There is also abundant evidence of altered reactivity of the maternal and placental vasculature and of the altered production of autocoids in preeclampsia. The occurrence of preeclampsia is increased in women with preexisting vascular disease and confers a long-term risk for development of cardiovascular disease. The vascular stress test of pregnancy thus identifies those women with a previously unrecognized at risk vascular system and promotes the development of preeclampsia. Preexisting maternal vascular dysfunction intensified by placental factors is possibly responsible for the individual pathologies of preeclampsia.

  18. Speleogenesis, geometry, and topology of caves: A quantitative study of 3D karst conduits

    Science.gov (United States)

    Jouves, Johan; Viseur, Sophie; Arfib, Bruno; Baudement, Cécile; Camus, Hubert; Collon, Pauline; Guglielmi, Yves

    2017-12-01

    Karst systems are hierarchically spatially organized three-dimensional (3D) networks of conduits behaving as drains for groundwater flow. Recently, geostatistical approaches proposed to generate karst networks from data and parameters stemming from analogous observed karst features. Other studies have qualitatively highlighted relationships between speleogenetic processes and cave patterns. However, few studies have been performed to quantitatively define these relationships. This paper reports a quantitative study of cave geometries and topologies that takes the underlying speleogenetic processes into account. In order to study the spatial organization of caves, a 3D numerical database was built from 26 caves, corresponding to 621 km of cumulative cave passages representative of the variety of karst network patterns. The database includes 3D speleological surveys for which the speleogenetic context is known, allowing the polygenic karst networks to be divided into 48 monogenic cave samples and classified into four cave patterns: vadose branchwork (VB), water-table cave (WTC), looping cave (LC), and angular maze (AM). Eight morphometric cave descriptors were calculated, four geometrical parameters (width-height ratio, tortuosity, curvature, and vertical index) and four topological ones (degree of node connectivity, α and γ graph indices, and ramification index) respectively. The results were validated by statistical analyses (Kruskal-Wallis test and PCA). The VB patterns are clearly distinct from AM ones and from a third group including WTC and LC. A quantitative database of cave morphology characteristics is provided, depending on their speleogenetic processes. These characteristics can be used to constrain and/or validate 3D geostatistical simulations. This study shows how important it is to relate the geometry and connectivity of cave networks to recharge and flow processes. Conversely, the approach developed here provides proxies to estimate the evolution of

  19. Processed allografts and type I collagen conduits for repair of peripheral nerve gaps.

    Science.gov (United States)

    Whitlock, Elizabeth L; Tuffaha, Sami H; Luciano, Janina P; Yan, Ying; Hunter, Daniel A; Magill, Christina K; Moore, Amy M; Tong, Alice Y; Mackinnon, Susan E; Borschel, Gregory H

    2009-06-01

    Autografting is the gold standard in the repair of peripheral nerve injuries that are not amenable to end-to-end coaptation. However, because autografts result in donor-site defects and are a limited resource, an effective substitute would be valuable. In a rat model, we compared isografts with Integra NeuraGen (NG) nerve guides, which are a commercially available type I collagen conduit, with processed rat allografts comparable to AxoGen's Avance human decellularized allograft product. In a 14-mm sciatic nerve gap model, isograft was superior to processed allograft, which was in turn superior to NG conduit at 6 weeks postoperatively (P < 0.05 for number of myelinated fibers both at midgraft and distal to the graft). At 12 weeks, these differences were no longer apparent. In a 28-mm graft model, isografts again performed better than processed allografts at both 6 and 22 weeks; regeneration through the NG conduit was often insufficient for analysis in this long graft model. Functional tests confirmed the superiority of isografts, although processed allografts permitted successful reinnervation of distal targets not seen in the NG conduit groups. Processed allografts were inherently non-immunogenic and maintained some internal laminin structure. We conclude that, particularly in a long gap model, nerve graft alternatives fail to confer the regenerative advantages of an isograft. However, AxoGen processed allografts are superior to a currently available conduit-style nerve guide, the Integra NeuraGen. They provide an alternative for reconstruction of short nerve gaps where a conduit might otherwise be used.

  20. Collagen-coated polylactic-glycolic acid (PLGA) seeded with neural-differentiated human mesenchymal stem cells as a potential nerve conduit.

    Science.gov (United States)

    Sulong, Ahmad Fadzli; Hassan, Nur Hidayah; Hwei, Ng Min; Lokanathan, Yogeswaran; Naicker, Amaramalar Selvi; Abdullah, Shalimar; Yusof, Mohd Reusmaazran; Htwe, Ohnmar; Idrus, Ruszymah Bt Hj; Haflah, Nor Hazla Mohamed

    2014-01-01

    Autologous nerve grafts to bridge nerve gaps pose various drawbacks. Nerve tissue engineering to promote nerve regeneration using artificial neural conduits has emerged as a promising alternative. To develop an artificial nerve conduit using collagen-coated polylactic-glycolic acid (PLGA) and to analyse the survivability and propagating ability of the neuro-differentiated human mesenchymal stem cells in this conduit. The PLGA conduit was constructed by dip-molding method and coated with collagen by immersing the conduit in collagen bath. The ultra structure of the conduits were examined before they were seeded with neural-differentiated human mesenchymal stem cells (nMSC) and implanted sub-muscularly on nude mice thighs. The non-collagen-coated PLGA conduit seeded with nMSC and non-seeded non-collagen-coated PLGA conduit were also implanted for comparison purposes. The survivability and propagation ability of nMSC was studied by histological and immunohistochemical analysis. The collagen-coated conduits had a smooth inner wall and a highly porous outer wall. Conduits coated with collagen and seeded with nMSCs produced the most number of cells after 3 weeks. The best conduit based on the number of cells contained within it after 3 weeks was the collagen-coated PLGA conduit seeded with neuro-transdifferentiated cells. The collagen-coated PLGA conduit found to be suitable for attachment, survival and proliferation of the nMSC. Minimal cell infiltration was found in the implanted conduits where nearly all of the cells found in the cell seeded conduits are non-mouse origin and have neural cell markers, which exhibit the biocompatibility of the conduits. The collagen-coated PLGA conduit is biocompatible, non-cytotoxic and suitable for use as artificial nerve conduits.

  1. Small scale high resolution LiDAR measurements of a subglacial conduit

    Science.gov (United States)

    Mankoff, K. D.; Gulley, J.

    2012-04-01

    We present direct measurements of surface roughness in a sub-glacial conduit system underneath the Rieperbreen Glacier, Svalbard, Norway. Data was collected with a low-cost (129 USD) Microsoft Kinect video game device used as a LIDAR sensor. Surface roughness is a primary control on water flow in rivers, channels, and cave conduit systems and understanding the effects of surface roughness on water flow has been problematic due to lack of direct measurements of roughness in natural systems. We use the ice scallop dimensions to derive flow velocity and explore implications of the changing roughness parameters as the cave grows and shrinks.

  2. [Experimental study on gradient of nerve growth factor immobilized conduits promoting peripheral nerve regeneration in rats].

    Science.gov (United States)

    Lin, Qiang; Cai, Yangtin; Li, Haoshen

    2014-02-01

    To study the effect of the loaded concentration gradient of nerve growth factor (NGF) immobilized conduit on rat peripheral nerve defect repair. The peripheral nerve conduits made of poly (epsilon-caprolactone)-block-poly (L-lactide-co-epsilon-caprolactone) were prepared with uniform loads or concentration gradient loads by combining differential absorption of NGF/silk fibroin (SF) coating, and the gradient of NGF was immobilized in the nerve conduits. ELISA method was used to exam the NGF release for 12 weeks in vitro. Twenty-four male Sprague Dawley rats (weighing, 220-250 g) were selected to establish the right sciatic nerve defect model (14 mm in length) and randomly divided into 4 groups according to repair methods. The transected nerve was bridged by a blank conduit without NGF in group A, by a conduit containing uniform loads of NGF in group B, by a conduit concentration gradient loads of NGF in group C, and by the autogenous nerve segment in group D. The gross observation, electrophysiological examination, histological observation, and transmission electron microscope observation were carried out to assess the nerve regeneration at 12 weeks after surgery. The cumulative release amount of NGF was (14.2 +/- 1.4) ng/mg and (13.7 +/- 1.3) ng/mg in gradient of NGF loaded conduits and uniform NGF loaded conduits respectively at 12 weeks, showing no significant difference (t = 0.564, P=0.570). All the animals survived to completion of the experiment; plantar ulcers occurred at 4 days, which healed at 12 weeks; groups C and D were better than groups A and B in ulcerative healing. At 12 weeks after surgery, the compound muscle action potential of group A was significantly lower than that of groups B, C, and D (P 0.05). The axon density of group C was significantly higher that of groups A, B, and D (P 0.05). Gradient of NGF loaded nerve condnits for rat sciatic nerve defect has similar results to autogenous nerve, with a good bridge, which can promote the sciatic

  3. [Clinical effect observation of biodegradable conduit small gap tublization repairing peripheral nerve injury].

    Science.gov (United States)

    Zhang, Pei-xun; Kou, Yu-hui; Han, Na; Dang, Yu; Xue, Feng; Wang, Tian-bing; Xu, Hai-lin; Chen, Jian-hai; Yang, Ming; Lu, Hao; Yin, Xiao-feng; Bai, Lu; Wang, Yan-hua; An, Shuai; Zhang, Dian-ying; Fu, Zhong-guo; Jiang, Bao-guo

    2012-12-18

    To observe the clinical effect of biodegradable conduit small gap tublization to repair peripheral nerve injury. In the study, 30 cases of fresh peripheral nerve injury in the upper extremities were recruited. After formally informed and obtaining the consent, the recruited patients were divided into the degradable chitin conduit tublization group (experimental group: 15 cases) and traditional epineurial neurorrhaphy group (control group: 15 cases). Their nerve functional recovery conditions were clinically observed according to the standard score methods provided by SHEN Ning-jiang and British Medical Research Council. The excellent and good rates of the overall nerve functional recovery were calculated. The electrophysiologic study was carried out after 6 months. Of the total 30 cases, 28 were followed up, and there were 14 cases in the degradable chitin conduit tublization group and traditional epineurial neurorrhaphy group. The operation procedure was very simple, and the mean suture time [(8.0±0.8) min] was 20% shorter than that of the traditional epineurial neurorrhaphy group [(10.0±0.6) min]. All the wounds in the degradable chitin conduit tublization group healed as expected without rejection, hypersensitive reaction or anomalous draining. Electrophysiology examination results after 6 months displayed that the sensory nerves conduction velocity recovery rate was 77.37% of the normal value, and motor nerve conduction velocity recovery rate was 70.09% in the degradable chitin conduit tublization group. The sensory nerves conduction velocity recovery rate was 61.69% of the normal value, and motor nerve conduction velocity recovery rate was 56.15% in the traditional epineurial neurorrhaphy group. The exact propability methods was applied in the comparison of sensory and motor nerve conduction velocity recovery rate, and there was no statistically significant of two groups(sensory nerve conduction velocity recovery rate P=0.678;motor nerve conduction velocity

  4. FDG-PET identification of infected pulmonary artery conduit following tetralogy of fallot (TOF) repair

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yu Yang; Williams, Hadyn; Pucar, Darko [Dept. of Radiology, Medical College of Georgia, Augusta (United States)

    2017-03-15

    Tetralogy of Fallot (TOF) is one of the most common forms of cyanotic congenital heart disease usually managed by serial surgical repairs. The repaired prosthetic valve or conduit is susceptible to life-threatening infection. FDG-PET is an effective alternative to evaluate the source of infection when other examinations are inconclusive. We report an unusual case of an infected pulmonary artery conduit after TOF repair although the echocardiogram was negative for vegetation, which was later confirmed by surgery and pathology. The case highlights the role of FDG-PET as a problem-solving tool for potential endocarditis and cardiac device infection cases after complex cardiac surgery.

  5. Havery Mudd 2014-2015 Computer Science Conduit Clinic Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Aspesi, G [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Bai, J [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Deese, R [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Shin, L [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-05-12

    Conduit, a new open-source library developed at Lawrence Livermore National Laboratories, provides a C++ application programming interface (API) to describe and access scientific data. Conduit’s primary use is for inmemory data exchange in high performance computing (HPC) applications. Our team tested and improved Conduit to make it more appealing to potential adopters in the HPC community. We extended Conduit’s capabilities by prototyping four libraries: one for parallel communication using MPI, one for I/O functionality, one for aggregating performance data, and one for data visualization.

  6. Percutaneous Nephrolithotomy, Ileal Conduit- Lithotripsy and Litholapaxy for a Neglected Encrusted Ureteral Stent

    Directory of Open Access Journals (Sweden)

    Andrés Gutierrez

    2017-11-01

    Full Text Available Urolithiasis can result as a complication of urinary diversión, favored by urinary stasis, intestinal mucus, urinary tract bacteriuria, the metabolic derangements and the presence of foreign bodies. We present a 52- year-old male who underwent radical cystectomy with construction of a Bricker uretero-ileostomy. 5 years later he was found with a forgotten ureteral stent, a 6 cm calculi occupying the whole ileal conduit and a 13 mm calculi in the left renal pelvis. We present our experience in the successful endourological management of an encrusted neglected ureteral stent in an ileal conduit, achieving a stone-free status without complications.

  7. Biological conduits combining bone marrow mesenchymal stem cells and extracellular matrix to treat long-segment sciatic nerve defects.

    Science.gov (United States)

    Wang, Yang; Li, Zheng-Wei; Luo, Min; Li, Ya-Jun; Zhang, Ke-Qiang

    2015-06-01

    The transplantation of polylactic glycolic acid conduits combining bone marrow mesenchymal stem cells and extracellular matrix gel for the repair of sciatic nerve injury is effective in some respects, but few data comparing the biomechanical factors related to the sciatic nerve are available. In the present study, rabbit models of 10-mm sciatic nerve defects were prepared. The rabbit models were repaired with autologous nerve, a polylactic glycolic acid conduit + bone marrow mesenchymal stem cells, or a polylactic glycolic acid conduit + bone marrow mesenchymal stem cells + extracellular matrix gel. After 24 weeks, mechanical testing was performed to determine the stress relaxation and creep parameters. Following sciatic nerve injury, the magnitudes of the stress decrease and strain increase at 7,200 seconds were largest in the polylactic glycolic acid conduit + bone marrow mesenchymal stem cells + extracellular matrix gel group, followed by the polylactic glycolic acid conduit + bone marrow mesenchymal stem cells group, and then the autologous nerve group. Hematoxylin-eosin staining demonstrated that compared with the polylactic glycolic acid conduit + bone marrow mesenchymal stem cells group and the autologous nerve group, a more complete sciatic nerve regeneration was found, including good myelination, regularly arranged nerve fibers, and a completely degraded and resorbed conduit, in the polylactic glycolic acid conduit + bone marrow mesenchymal stem cells + extracellular matrix gel group. These results indicate that bridging 10-mm sciatic nerve defects with a polylactic glycolic acid conduit + bone marrow mesenchymal stem cells + extracellular matrix gel construct increases the stress relaxation under a constant strain, reducing anastomotic tension. Large elongations under a constant physiological load can limit the anastomotic opening and shift, which is beneficial for the regeneration and functional reconstruction of sciatic nerve. Better regeneration was

  8. The QBO as potential amplifier and conduit to lower altitudes of solar cycle influence

    Directory of Open Access Journals (Sweden)

    H. G. Mayr

    2007-06-01

    tapping the momentum from the upward propagating gravity waves. Influenced and amplified by wave processes, the QBO thus acts as conduit to transfer to lower altitudes the larger SC variations in the UV absorbed in the mesosphere. Our model produces in the temperature variations of the QBO and EAO measurable SC modulations at polar latitudes near the tropopause. The effects are apparently generated by the meridional circulation, and planetary waves presumably, which redistribute the energy from the equatorial region where the waves are very effective in amplifying the SC influence.

  9. Epigenetic Diabetic Vascular Complications

    Directory of Open Access Journals (Sweden)

    Ali Ahmadzadeh-Amiri

    2016-01-01

    Full Text Available Diabetic vascular complications (DVC influence several vital organ systems including cardiovascular, renal, ocular and nervous systems making it a major public health problem. Although extensive researches were performed in this field, the exact mechanisms responsible for these organ damages in diabetes remain obscure. Several metabolic disturbances have been involved in its complication and change in genes associated with these pathways occurred. Gene expression to produce a biologically active protein can be controlled by transcriptional and translational alteration on the head of genes without change in nucleotide composition. These epigenetic adjustments are steady, but possibly reversible and can be transmitted to future generation. Gene expression can be regulated by three epigenetic mechanisms including DNA methylation, histone modifications and noncoding microRNAs (miRNAs activity. Epigenetic studies must be directed to better realize the role of epigenetic changes to the etiology of DVC and knowledge of epigenetic would play a pivotal role in the application of individualized medicine. Application and development of high technology sequencing combined with more sensitive and advanced methodologies for epigenome studying help to determine specific epigenetic events that stimulate gene responses in patients with diabetes mellitus.

  10. Vascular grading of angiogenesis

    DEFF Research Database (Denmark)

    Hansen, S; Grabau, D A; Sørensen, Flemming Brandt

    2000-01-01

    years and 4 months. The microvessels were immunohistochemically stained by antibodies against CD34. Angiogenesis was graded semiquantitatively by subjective scoring into three groups according to the expected number of microvessels in the most vascular tumour area. The vascular grading between observers...

  11. 26 CFR 1.6081-7 - Automatic extension of time to file Real Estate Mortgage Investment Conduit (REMIC) income tax...

    Science.gov (United States)

    2010-04-01

    ... 26 Internal Revenue 13 2010-04-01 2010-04-01 false Automatic extension of time to file Real Estate... Time for Filing Returns § 1.6081-7 Automatic extension of time to file Real Estate Mortgage Investment Conduit (REMIC) income tax return. (a) In general. A Real Estate Mortgage Investment Conduit (REMIC...

  12. Nitric oxide permits hypoxia-induced lymphatic perfusion by controlling arterial-lymphatic conduits in zebrafish and glass catfish

    DEFF Research Database (Denmark)

    Dahl Ejby Jensen, Lasse; Cao, Renhai; Hedlund, Eva-Maria

    2009-01-01

    and lymphatic perfusion. Here we show in the adult zebrafish and glass catfish (Kryptopterus bicirrhis) that blood-lymphatic conduits directly connect arterial vessels to the lymphatic system. Under hypoxic conditions, arterial-lymphatic conduits (ALCs) became highly dilated and linearized by NO...

  13. Vascular cognitive impairment and vascular dementia

    Directory of Open Access Journals (Sweden)

    Klavdija Ovčar

    2017-09-01

    Full Text Available In the developed world, five to ten percent of people older than 65 years have dementia. One fifth of dementia etiologies are due to vascular brain lesions (VaD – vascular dementia. A milder form is called vascular cognitive impairment (VCI. The main clinical criteria for VaD are: 1. cognitive decline verified with standardized cognitive test/scale, 2. evidence of the associated vascular brain lesion, 3. excluded reversible causes of cognitive decline. The main risk factors for VaD are age, atherosclerosis, diabetes and hypertension. They play a key role in pathogenesis of the cognitive impairment. Depending on the damaged brain region, different cognitive domains may be affected with or without other neurological signs. These diversities in the clinical picture challenge the correct diagnosis. Unique feature of VaD is its progression, which can be stopped, if patients receive an appropriate treatment.The treatment of VCI and VaD symptoms is similar to that in Alzheimer’s disease. More importantly, VCI may be slowed down or even stopped with proper secondary stroke prevention and good rehabilitation. The most efficient is primary stroke prevention with healthy lifestyle and treatment of acquired risk factors.

  14. Vascular disease burden in Indian subjects with vascular dementia.

    Science.gov (United States)

    Chandra, Mina; Anand, Kuljeet Singh

    2015-01-01

    Vascular disease factors like hypertension, diabetes mellitus, dyslipidaemia, and ischaemic heart disease contribute to the development of vascular dementia. As comorbidity of vascular disease factors in vascular dementia is common, we investigated the vascular disease burden in subjects with vascular dementia. To investigate the vascular disease burden due to four vascular disease factors: hypertension, diabetes mellitus, dyslipidaemia, and ischaemic heart disease in Indian subjects with vascular dementia. In this study, 159 subjects with probable vascular dementia (as per NINDS-AIREN criteria) attending the memory clinic at a tertiary care hospital were assessed for the presence of hypertension, diabetes mellitus, dyslipidaemia, and ischaemic heart disease using standardised operational definitions and for severity of dementia on the Clinical Dementia Rating (CDR) scale. The data obtained was subjected to appropriate statistical analysis. Dyslipidaemia (79.25 per cent) was the most common vascular disease factor followed by hypertension (73.58 per cent), ischaemic heart disease (58.49 per cent), and diabetes mellitus (40.80 per cent). Most subjects (81.1 per cent) had two or more vascular disease factors. Subjects with more severe dementia had more vascular disease factors (sig 0.001). People with moderate to severe dementia have a significantly higher vascular disease burden; therefore, higher vascular disease burden may be considered as a poor prognostic marker in vascular dementia. Subjects with vascular dementia and their caregivers must manage cognitive impairment and ADL alongside managing serious comorbid vascular diseases that may worsen the dementia.

  15. Vascular Aging and Arterial Stiffness

    Directory of Open Access Journals (Sweden)

    Luana de Rezende Mikael

    Full Text Available Abstract Cardiovascular diseases (CVD account annually for almost one third of all deaths worldwide. Among the CVD, systemic arterial hypertension (SAH is related to more than half of those outcomes. Type 2 diabetes mellitus is an independent risk factor for SAH because it causes functional and structural damage to the arterial wall, leading to stiffness. Several studies have related oxidative stress, production of free radicals, and neuroendocrine and genetic changes to the physiopathogenesis of vascular aging. Indirect ways to analyze that aging process have been widely studied, pulse wave velocity (PWV being considered gold standard to assess arterial stiffness, because there is large epidemiological evidence of its predictive value for cardiovascular events, and it requires little technical knowledge to be performed. A pulse wave is generated during each cardiac contraction and travels along the arterial bed until finding peripheral resistance or any bifurcation point, determining the appearance of a reflected wave. In young individuals, arteries tend to be more elastic, therefore, the reflected wave occurs later in the cardiac cycle, reaching the heart during diastole. In older individuals, however, the reflected wave occurs earlier, reaching the heart during systole. Because PWV is an important biomarker of vascular damage, highly valuable in determining the patient’s global cardiovascular risk, we chose to review the articles on vascular aging in the context of cardiovascular risk factors and the tools available to the early identification of that damage.

  16. 3D bioprinting of heterogeneous aortic valve conduits with alginate/gelatin hydrogels.

    Science.gov (United States)

    Duan, Bin; Hockaday, Laura A; Kang, Kevin H; Butcher, Jonathan T

    2013-05-01

    Heart valve disease is a serious and growing public health problem for which prosthetic replacement is most commonly indicated. Current prosthetic devices are inadequate for younger adults and growing children. Tissue engineered living aortic valve conduits have potential for remodeling, regeneration, and growth, but fabricating natural anatomical complexity with cellular heterogeneity remain challenging. In the current study, we implement 3D bioprinting to fabricate living alginate/gelatin hydrogel valve conduits with anatomical architecture and direct incorporation of dual cell types in a regionally constrained manner. Encapsulated aortic root sinus smooth muscle cells (SMC) and aortic valve leaflet interstitial cells (VIC) were viable within alginate/gelatin hydrogel discs over 7 days in culture. Acellular 3D printed hydrogels exhibited reduced modulus, ultimate strength, and peak strain reducing slightly over 7-day culture, while the tensile biomechanics of cell-laden hydrogels were maintained. Aortic valve conduits were successfully bioprinted with direct encapsulation of SMC in the valve root and VIC in the leaflets. Both cell types were viable (81.4 ± 3.4% for SMC and 83.2 ± 4.0% for VIC) within 3D printed tissues. Encapsulated SMC expressed elevated alpha-smooth muscle actin, while VIC expressed elevated vimentin. These results demonstrate that anatomically complex, heterogeneously encapsulated aortic valve hydrogel conduits can be fabricated with 3D bioprinting. Copyright © 2012 Wiley Periodicals, Inc.

  17. Percutaneous transthoracic computed tomography-guided AICD insertion in a patient with extracardiac Fontan conduit.

    LENUS (Irish Health Repository)

    Murphy, Darra T

    2011-02-01

    Percutaneous pulmonary venous atrial puncture was performed under computed tomography guidance to successfully place an automated implantable cardiac defibrillator into a 26-year-old patient with extracardiac Fontan conduit who had presented with two out-of-hospital cardiac arrests. The procedure avoided the need for lead placement at thoracotomy.

  18. 30 CFR 77.700 - Grounding metallic sheaths, armors, and conduits enclosing power conductors.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Grounding metallic sheaths, armors, and conduits enclosing power conductors. 77.700 Section 77.700 Mineral Resources MINE SAFETY AND HEALTH... AND SURFACE WORK AREAS OF UNDERGROUND COAL MINES Grounding § 77.700 Grounding metallic sheaths, armors...

  19. A Physicochemically Optimized and Neuroconductive Biphasic Nerve Guidance Conduit for Peripheral Nerve Repair.

    Science.gov (United States)

    Ryan, Alan J; Lackington, William A; Hibbitts, Alan J; Matheson, Austyn; Alekseeva, Tijna; Stejskalova, Anna; Roche, Phoebe; O'Brien, Fergal J

    2017-12-01

    Clinically available hollow nerve guidance conduits (NGCs) have had limited success in treating large peripheral nerve injuries. This study aims to develop a biphasic NGC combining a physicochemically optimized collagen outer conduit to bridge the transected nerve, and a neuroconductive hyaluronic acid-based luminal filler to support regeneration. The outer conduit is mechanically optimized by manipulating crosslinking and collagen density, allowing the engineering of a high wall permeability to mitigate the risk of neuroma formation, while also maintaining physiologically relevant stiffness and enzymatic degradation tuned to coincide with regeneration rates. Freeze-drying is used to seamlessly integrate the luminal filler into the conduit, creating a longitudinally aligned pore microarchitecture. The luminal stiffness is modulated to support Schwann cells, with laminin incorporation further enhancing bioactivity by improving cell attachment and metabolic activity. Additionally, this biphasic NGC is shown to support neurogenesis and gliogenesis of neural progenitor cells and axonal outgrowth from dorsal root ganglia. These findings highlight the paradigm that a successful NGC requires the concerted optimization of both a mechanical support phase capable of bridging a nerve defect and a neuroconductive phase with an architecture capable of supporting both Schwann cells and neurons in order to achieve functional regenerative outcome. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Determinants of right ventricular outflow tract conduit longevity: a multinational analysis

    NARCIS (Netherlands)

    Niemantsverdriet, Marieke B. A.; Ottenkamp, Jaap; Gauvreau, Kimberlee; del Nido, Pedro J.; Hazenkamp, Mark G.; Jenkins, Kathy J.

    2008-01-01

    OBJECTIVE: The need for conduit replacement in the growing child remains a major problem after right ventricular outflow tract reconstruction. We compared two diverse surgical centers with considerable practice variation in Europe and the United States to identify modifiable risk factors that can

  1. Heterogeneity in conduit artery function in humans: impact of arterial size.

    NARCIS (Netherlands)

    Thijssen, D.H.J.; Dawson, E.A.; Black, M.A.; Hopman, M.T.E.; Cable, N.T.; Green, D.J.

    2008-01-01

    To determine whether conduit artery size affects functional responses, we compared the magnitude, time course, and eliciting shear rate stimulus for flow-mediated dilation (FMD) in healthy men (n = 20; 31 +/- 7 yr). Upper limb (brachial and radial) and lower limb (common and superficial femoral) FMD

  2. 26 CFR 1.67-3 - Allocation of expenses by real estate mortgage investment conduits.

    Science.gov (United States)

    2010-04-01

    ... 26 Internal Revenue 2 2010-04-01 2010-04-01 false Allocation of expenses by real estate mortgage investment conduits. 1.67-3 Section 1.67-3 Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF THE... Gross Income, and Taxable Income § 1.67-3 Allocation of expenses by real estate mortgage investment...

  3. Exercise capacity in children after total cavopulmonary connection: Lateral tunnel versus extracardiac conduit technique

    NARCIS (Netherlands)

    Bossers, S.S.; Helbing, W.A.; Duppen, N.; Kuipers, I.M.; Schokking, M.; Hazekamp, M.G.; Bogers, A.J.; Harkel, A.D. Ten; Takken, T.

    2014-01-01

    OBJECTIVES: In patients with univentricular heart disease, the total cavopulmonary connection (TCPC) is the preferred treatment. TCPC can be performed using the intra-atrial lateral tunnel (ILT) or extracardiac conduit (ECC) technique. The purpose of the present study was to evaluate exercise

  4. Enhancing Peripheral Nerve Regeneration with a Novel Drug-Delivering Nerve Conduit

    Science.gov (United States)

    2015-10-01

    Specifically fertilized chicken eggs were incubated at ~39°C under 100% relative humidity for 12 days. Dorsal root ganglions (DGRs) were dissected from...developed fabrication and sterilization protocols for a nerve conduit device with dual drug reservoirs and tested the efficacy of the device using

  5. Microfluidics embedded within extracellular matrix to define vascular architectures and pattern diffusive gradients.

    Science.gov (United States)

    Baker, Brendon M; Trappmann, Britta; Stapleton, Sarah C; Toro, Esteban; Chen, Christopher S

    2013-08-21

    Gradients of diffusive molecules within 3D extracellular matrix (ECM) are essential in guiding many processes such as development, angiogenesis, and cancer. The spatial distribution of factors that guide these processes is complex, dictated by the distribution and architecture of vasculature and presence of surrounding cells, which can serve as sources or sinks of factors. To generate temporally and spatially defined soluble gradients within a 3D cell culture environment, we developed an approach to patterning microfluidically ported microchannels that pass through a 3D ECM. Micromolded networks of sacrificial conduits ensconced within an ECM gel precursor solution are dissolved following ECM gelation to yield functional microfluidic channels. The dimensions and spatial layout of channels are readily dictated using photolithographic methods, and channels are connected to external flow via a gasket that also serves to house the 3D ECM. We demonstrated sustained spatial patterning of diffusive gradients dependent on the architecture of the microfluidic network, as well as the ability to independently populate cells in either the channels or surrounding ECM, enabling the study of 3D morphogenetic processes. To highlight the utility of this approach, we generated model vascular networks by lining the channels with endothelial cells and examined how channel architecture, through its effects on diffusion patterns, can guide the location and morphology of endothelial sprouting from the channels. We show that locations of strongest gradients define positions of angiogenic sprouting, suggesting a mechanism by which angiogenesis is regulated in vivo and a potential means to spatially defining vasculature in tissue engineering applications. This flexible 3D microfluidic approach should have utility in modeling simple tissues and will aid in the screening and identification of soluble factor conditions that drive morphogenetic events such as angiogenesis.

  6. Surface Features Parameterization and Equivalent Roughness Height Estimation of a Real Subglacial Conduit in the Arctic

    Science.gov (United States)

    Chen, Y.; Liu, X.; Manko ff, K. D.; Gulley, J. D.

    2016-12-01

    The surfaces of subglacial conduits are very complex, coupling multi-scale roughness, large sinuosity, and cross-sectional variations together. Those features significantly affect the friction law and drainage efficiency inside the conduit by altering velocity and pressure distributions, thus posing considerable influences on the dynamic development of the conduit. Parameterizing the above surface features is a first step towards understanding their hydraulic influences. A Matlab package is developed to extract the roughness field, the conduit centerline, and associated area and curvature data from the conduit surface, acquired from 3D scanning. By using those data, the characteristic vertical and horizontal roughness scales are then estimated based on the structure functions. The centerline sinuosities, defined through three concepts, i.e., the traditional definition of a fluvial river, entropy-based sinuosity, and curvature-based sinuosity, are also calculated and compared. The cross-sectional area and equivalent circular diameter along the centerline are also calculated. Among those features, the roughness is especially important due to its pivotal role in determining the wall friction, and thus an estimation of the equivalent roughness height is of great importance. To achieve such a goal, the original conduit is firstly simplified into a straight smooth pipe with the same volume and centerline length, and the roughness field obtained above is then reconstructed into the simplified pipe. An OpenFOAM-based Large-eddy-simulation (LES) is then performed based on the reconstructed pipe. Considering that the Reynolds number is of the order 106, and the relative roughness is larger than 5% for 60% of the conduit, we test the validity of the resistance law for completely rough pipe. The friction factor is calculated based on the pressure drop and mean velocity in the simulation. Working together, the equivalent roughness height can be calculated. However, whether the

  7. SUIVI DE LA MIGRATION D’AVALAISON DES ANGUILLES PAR UNE CONDUITE DE DEBIT RESERVE

    Directory of Open Access Journals (Sweden)

    LEGAULT A.

    2003-07-01

    Full Text Available Le suivi de la migration catadrome de l’anguille par une conduite de débit réservé a été réalisé sur le barrage de la retenue de Bois Joli sur le Frémur (dénivelé : 13,7 m ; 3 millions de m3. Une partie des migrateurs utilise cette conduite, au début de la saison de dévalaison quand elle représente la seule voie de transit mais également plus tard, lorsque le barrage déverse et que s’ouvre ainsi une seconde voie de passage. En raison des faibles débits d’alimentation et de l’implantation de l’entrée de la conduite on peut supposer que les anguilles prospectent la retenue pour trouver une voie de transit. L’efficacité de l’équipement, qui s’établit à 12 % de la dévalaison totale, concourt donc pour une part non négligeable au transit des anguilles. La partition des débits entre les différentes voies de migration semblerait essentielle pour définir leur efficacité. Malgré l’aménagement de la conduite, on observe une mortalité de 11 % des anguilles qui l’empruntent. Elle semble essentiellement liée à l’abrasion contre les parois et le papillon de la vanne. Dans de nombreux cas, la mortalité lors du passage dans les conduites de débit réservé doit être très importante, voire totale en raison de leur configuration et de leur mode de gestion. Cette mortalité tend à réduire le nombre des géniteurs produit par le bassin versant. Les anguilles marquées qui ont franchi le barrage grâce à la conduite avant le pic de migration stoppent leur progression en aval. Elles la reprennent quelques semaines plus tard quand le barrage déverse ou l’année suivante. Ce second constat confirme les effets des retenues sur la vitesse de migration. L’utilisation des conduites de débit réservé par les anguilles d’avalaison devrait être prise en compte lors de leur conception et de leur gestion afin de réduire les risques de mortalité.

  8. Vascular remodelling in asthma.

    Science.gov (United States)

    Walters, Eugene Haydn; Soltani, Amir; Reid, David William; Ward, Chris

    2008-02-01

    We review the recent literature, focusing on 2006 and 2007, to produce an update on the patho-biology of angiogenesis and vascular endothelial growth factor in the asthmatic airway. In terms of conceptual development in asthma research, airway inflammation and remodelling have been regarded as separate processes or perhaps as sequential, with early inflammation leading later to remodelling. Recent insights identify a central role for vascular endothelial growth factor in stimulating both inflammation and vascular remodelling coincidentally, with the full panoply of vascular endothelial growth factor mediated events being complex and wide. Both nitric oxide and matrix metalloproteinase-9 induction may be important downstream pathogenic mechanisms. Virus-mediated exacerbations are a prime manifestation of the oscillating trajectory of clinical asthma. The early stimulation of vascular endothelial growth factor production is probably a central aetiological mechanism, with secondary inflammation and angiogenesis. The time scale of the latter, especially, fits with the time scale of clinico-physiological changes after exacerbation. These vascular endothelial growth factor induced changes are potentially modifiable with therapy. Insights into the importance of vascular endothelial growth factor and angiogenesis in asthma pathogenesis now lead to potential new therapeutic possibilities and elucidate why recent advances in asthma therapeutics have been so successful.

  9. Robot-assisted intracorporeal ileal conduit: Marionette technique and initial experience at Roswell Park Cancer Institute.

    Science.gov (United States)

    Guru, Khurshid; Seixas-Mikelus, Stéfanie A; Hussain, Abid; Blumenfeld, Aaron J; Nyquist, John; Chandrasekhar, Rameela; Wilding, Gregory E

    2010-10-01

    To present our technique and initial experience with patients who underwent robot-assisted intracorporeal creation of ileal conduit and to compare them with patients who underwent extracorporeal ileal diversion after robot-assisted radical cystectomy. Twenty-six patients diagnosed with invasive transitional cell carcinoma of the bladder underwent a robot-assisted radical cystectomy with bilateral extended pelvic lymphadenectomy with ileal conduit diversion. Total intracorporeal ileal conduit creation was performed in the last 13 patients. Operative data and short-term outcomes between the 2 groups were assessed. The novel surgical technique for intracorporeal ileal conduit will be presented. The intracorporeal group (IC) included 2 female and 11 male patients (mean age 71 years). The extracorporeal group (EC) included 4 female and 9 male patients (mean age 66 years). No significant differences were noted between the groups in terms of patient age, BMI, sex, prior surgery, or pathologic stage. Overall operative time and intraoperative complications were similar. No significant differences were noted between the 2 groups in terms of diversion time or estimated blood loss. There were 4 complications recorded in IC patients, including nonspecific colitis, small bowel obstruction requiring exploratory laparotomy with lysis of adhesions, a urine leak that eventually resolved but required a temporary nephrostomy tube, and a fever of unknown origin that resolved without intervention. Robot-assisted intracorporeal ileal conduit can be accomplished safely with acceptable operative times even during early experience. Larger series with favorable results will be required to add this new paradigm to minimally invasive surgery for bladder cancer. Copyright © 2010 Elsevier Inc. All rights reserved.

  10. Magnetic domain wall conduits for single cell applications

    DEFF Research Database (Denmark)

    Donolato, Marco; Torti, A.; Kostesha, Natalie

    2011-01-01

    The ability to trap, manipulate and release single cells on a surface is important both for fundamental studies of cellular processes and for the development of novel lab-on-chip miniaturized tools for biological and medical applications. In this paper we demonstrate how magnetic domain walls...... generated in micro- and nano-structures fabricated on a chip surface can be used to handle single yeast cells labeled with magnetic beads. In detail, first we show that the proposed approach maintains the microorganism viable, as proven by monitoring the division of labeled yeast cells trapped by domain...

  11. 3D Bioprinting for Vascularized Tissue Fabrication.

    Science.gov (United States)

    Richards, Dylan; Jia, Jia; Yost, Michael; Markwald, Roger; Mei, Ying

    2017-01-01

    3D bioprinting holds remarkable promise for rapid fabrication of 3D tissue engineering constructs. Given its scalability, reproducibility, and precise multi-dimensional control that traditional fabrication methods do not provide, 3D bioprinting provides a powerful means to address one of the major challenges in tissue engineering: vascularization. Moderate success of current tissue engineering strategies have been attributed to the current inability to fabricate thick tissue engineering constructs that contain endogenous, engineered vasculature or nutrient channels that can integrate with the host tissue. Successful fabrication of a vascularized tissue construct requires synergy between high throughput, high-resolution bioprinting of larger perfusable channels and instructive bioink that promotes angiogenic sprouting and neovascularization. This review aims to cover the recent progress in the field of 3D bioprinting of vascularized tissues. It will cover the methods of bioprinting vascularized constructs, bioink for vascularization, and perspectives on recent innovations in 3D printing and biomaterials for the next generation of 3D bioprinting for vascularized tissue fabrication.

  12. Drinking-water powered small hydro system in the connection conduit between Praez and Raschlengas; Gemeinde Praez, Wasserversorgung Erneuerung. Verbindungsleitung Praez-Raschlegnas mit Trinkwasserkraftwerk Raschlegnas

    Energy Technology Data Exchange (ETDEWEB)

    Camenisch, M.

    2009-05-15

    This illustrated final report for the Swiss Federal Office of Energy (SFOE) takes a look at a project involving a drinking-water powered small hydro system in the municipality of Praez, Switzerland. The project involves the replacement of an old connection conduit and proposes the installation of small hydro project to use surplus water to generate power. The report presents figures and calculations on the possible installation of equipment for the generation of 32 kW electrical power in an old bakery house. The report contains details of existing installations, water quantities and specifications for the proposed generation facilities. The economic feasibility of the proposed hydro-power system is discussed and recommendations for further work are made. An appendix contains photos and further documentation on the project.

  13. Impact of a smoking cessation lifestyle intervention on vascular mechanics in young women.

    Science.gov (United States)

    Nielson, Chantelle A; Frances, Maria F; Fitzgeorge, Lyndsay; Prapavessis, Harry; Zamir, Mair; Shoemaker, J Kevin

    2014-05-01

    We tested the hypotheses that smoking-induced changes in vascular mechanics would be detected earlier in the lumped properties of peripheral vascular beds, which include the properties of microvasculature, than in the local properties of central conduits, and that such changes are reversible with lifestyle changes that include smoking cessation and exercise. Vascular measures were made in 53 young (18-40 years) female smokers and 25 age-matched non-smokers. Twenty-two of the smokers were tested before and after a 14-week smoking cessation program and, of these, 13 were tested again after 52 weeks of smoking cessation. Compared with non-smokers, lumped forearm vascular bed compliance (C: mL/mm Hg) was lower, while lumped viscoelasticity (K: mm Hg/(mL·min)) and resistance (R: mm Hg/(mL·min)) were higher in the smoker group. Neither the carotid-to-toe pulse wave velocity nor local carotid artery elasticity indices were different between groups. Compared with non-smokers, brachial artery distensibility was less, and other markers of stiffness higher, in the smoker group. At 14 and 52 weeks of smoking cessation, forearm vascular R was reduced and C was increased while K was unchanged. The changes in C and R occurred while maintaining a constant R×C value, which represents a dynamic time constant. Thus, early changes in K were observed in the forearm vascular bed of smokers, which were not reflected in the local properties of central conduit vessels. Forearm C, but not K, was reversed following smoking cessation, a finding that may represent a persistent effect of smoking on the intercellular matrix of the vessel wall.

  14. The Development of the CONDUIT Advanced Control System Design and Evaluation Interface with a Case Study Application to an Advanced Fly by Wire Helicopter Design

    Science.gov (United States)

    Colbourne, Jason

    1999-01-01

    This report details the development and use of CONDUIT (Control Designer's Unified Interface). CONDUIT is a design tool created at Ames Research Center for the purpose of evaluating and optimizing aircraft control systems against handling qualities. Three detailed design problems addressing the RASCAL UH-60A Black Hawk are included in this report to show the application of CONDUIT to helicopter control system design.

  15. Understanding Vascular Endothelium

    OpenAIRE

    Gimbrone, Michael A.

    2014-01-01

    Understanding Vascular Endothelium : Nature’s Container for Blood The entire cardiovascular system, from the chambers of the heart to the smallest capillaries of peripheral tissues, is lined by a single-cell-thick continuous layer—the vascular endothelium. For many years, this gossamer membrane was thought to function largely as an inert barrier, passively separating the reactive components of the circulating blood from the cells and connective tissue matrix of the various organs of the body....

  16. Hypercholesterolaemia and vascular dementia

    OpenAIRE

    Appleton, Jason P.; Scutt, Polly; Sprigg, Nikola; Bath, Philip M.

    2017-01-01

    Vascular dementia (VaD) is the second commonest cause of dementia. Stroke is the leading cause of disability in adults in developed countries, the second major cause of dementia and the third commonest cause of death. Traditional vascular risk factors–diabetes, hypercholesterolaemia, hypertension and smoking–are implicated as risk factors for VaD. The associations between cholesterol and small vessel disease (SVD), stroke, cognitive impairment and subsequent dementia are complex and as yet no...

  17. Improved axonal regeneration of transected spinal cord mediated by multichannel collagen conduits functionalized with neurotrophin-3 gene.

    Science.gov (United States)

    Yao, L; Daly, W; Newland, B; Yao, S; Wang, W; Chen, B K K; Madigan, N; Windebank, A; Pandit, A

    2013-12-01

    Functionalized biomaterial scaffolds targeted at improving axonal regeneration by enhancing guided axonal growth provide a promising approach for the repair of spinal cord injury. Collagen neural conduits provide structural guidance for neural tissue regeneration, and in this study it is shown that these conduits can also act as a reservoir for sustained gene delivery. Either a G-luciferase marker gene or a neurotrophin-3-encoding gene, complexed to a non-viral, cyclized, PEGylated transfection vector, was loaded within a multichannel collagen conduit. The complexed genes were then released in a controlled fashion using a dual release system both in vitro and in vivo. For evaluation of their biological performance, the loaded conduits were implanted into the completely transected rat thoracic spinal cord (T8-T10). Aligned axon regeneration through the channels of conduits was observed one month post-surgery. The conduits delivering neurotrophin-3 polyplexes resulted in significantly increased neurotrophin-3 levels in the surrounding tissue and a statistically higher number of regenerated axons versus the control conduits (Pspinal cord.

  18. The fate of pulmonary conduits after the Ross procedure: longitudinal analysis of the German-Dutch Ross registry experience.

    Science.gov (United States)

    Mokhles, M Mostafa; Charitos, Efstratios I; Stierle, Ulrich; Rajeswaran, Jeevanantham; Blackstone, Eugene H; Bogers, Ad J J C; Takkenberg, Johanna J M; Sievers, Hans-Hinrich

    2013-12-01

    To assess allograft function over time after the Ross procedure. Prospective multicentre registry. 10 cardiac surgery departments in Germany and the Netherlands. Among 1775 consecutive adult patients (mean age 43.7±12.0) who underwent the Ross procedure, 1645 (93%) received an allograft (pulmonary=1612, aortic=12, unknown=21), 120 (6%) a bioprosthesis, and 5 (0.3%) a bovine jugular vein for right ventricular outflow tract reconstruction. Ross procedure. Using non-linear longitudinal models, serial echocardiographic records (N=6950) were studied to assess pulmonary conduit function over time in patients who had undergone the Ross procedure, with a maximum echocardiographic follow-up of 22.4 years (5.5±4.3 years). A slight increase in pulmonary conduit regurgitation grade was observed during follow-up. Freedom from regurgitation grade ≥2+ was 95% after 14 years. Female patient gender, allograft use (compared to bioprosthesis), male donor gender, antibiotic treatment of the allograft, and specific surgical adjustments were associated with a significantly higher regurgitation grade. Mean conduit gradient increased from 4.7 mm Hg at 1 month to 10 mm Hg by 14 years, while peak gradient increased from 8.4 to 18.5 mm Hg. Smaller conduit diameter, male patient gender, younger patient age, younger donor age, and use of a bioprosthesis were associated with a significantly higher mean and peak gradient. During follow-up, 76 reinterventions were required on the pulmonary conduit in 67 patients. Freedom from pulmonary conduit reintervention or dysfunction was 90.6% (95% CI 87.7% to 93.6%) and 79.5% (95% CI 75.2% to 84.0%) at 15 years, respectively. Echocardiographic follow-up of pulmonary conduits shows good conduit durability. Clinically important conduit regurgitation and stenosis are rare in adult patients after the Ross operation.

  19. A numerical code of explosive conduit flows constrained by large-scale experiments

    Science.gov (United States)

    Dioguardi, Fabio; de Lorenzo, Salvatore; Dellino, Pierfrancesco

    2010-05-01

    Conduit exit conditions during explosive eruptions play a major role in determining the rate and style of the eruptive column. The main parameter characterizing the eruptive mixture at conduit exit is mass eruption rate (MER), which is the product of velocity, density and conduit section area. This was perceived by the first researchers, who constructed theoretical model on the dynamics of explosive eruptions (Wilson et al., 1980; Woods, 1988; Bursik and Woods, 1991). Numerical modelling also helped scientists in the understanding of the complex dynamics of this kind of eruptions (Macedonio et al., 2005; Neri et al., 1998; Papale, 2001; Papale et al., 1998). Finally, the first large scale experiments on the mechanics of eruptive columns and pyroclastic flows (Dellino et al., 2007) allowed the development of an empirical model for the prediction of exit velocity of eruptive mixtures and the conditions of existence of the main eruptive styles (Dellino et al., 2009). Since the experiments were successfully scaled to real eruptions, we implemented a numerical model that reproduces the main quantities measured in the experiments, with the aim of eventually extending the model to the natural case. This would be the first time that a numerical model on the mechanics of explosive eruptions is validated against large-scale experiments. A steady 1-D two phase numerical model of the conduit flow is presented here. In this model the equations of conservation of mass and momentum for gas and volcanic particles are solved via a Runge-Kutta method with an adaptive stepsize. The numerical model is implemented in a code written in Fortran 77 language. The use of an adaptive stepsize control over the Runge-Kutta method allows the achievement of a predetermined accuracy (in this case of the order of 10-5) with minimum computational effort. All the conditions of the experimental runs are implemented and the velocity field is initialized using the empirical model for mixture velocity

  20. Early surgical experience of right ventricular outflow reconstruction with the RVOT Elan conduit in adults and adolescents with congenital heart disease.

    Science.gov (United States)

    Nozohoor, Shahab; Johansson, Sune; Gustafsson, Ronny

    2014-01-01

    Several types of valves and valved conduits have been developed for right ventricular outflow tract reconstruction and yet no one has provided prolonged satisfactory hemodynamic performance. The RVOT Elan is a bioprosthetic heart valve conduit constructed from a vascular graft and a porcine stentless valve indicated specifically for right ventricular outflow tract reconstruction. The present study aimed to evaluate the early clinical and hemodynamic results following implantation of the RVOT Elan in adults and adolescents with congenitally corrected right ventricular outflow tract anomalies requiring reintervention. Nineteen consecutive patients underwent right ventricular outflow reconstruction with the RVOT Elan between June 2012 and May 2013 in a nationally centralized center for surgery of patients with congenital heart disease. Pulmonic transvalvular gradients were evaluated with echocardiograms at discharge. Postoperative data on adverse clinical events were obtained from patient records. Follow-up was performed in October 2013 and was 100% complete (mean 331 ± 102, median 315 days). There were no intraoperative deaths. Survival at 30 days was 100% and there were no late deaths. The mean gradients were 14, 15, 13 mm Hg for the 21, 23, and 25 mm valve size, respectively. There were no cases of endocarditis or valve thrombosis. Freedom from reoperation for any cause was 100%. Freedom from cardiovascular adverse events was 94.4% (data 90.5% complete). The RVOT Elan demonstrates excellent early clinical and favorable hemodynamic results, with low transvalvular gradients, good flow characteristics, and a complete freedom from reoperation. Ease of implantation is evidenced by favorable ischemic times. Long-term results are awaited. © 2014 Wiley Periodicals, Inc.

  1. Autotaxin overexpression causes embryonic lethality and vascular defects.

    Directory of Open Access Journals (Sweden)

    Hiroshi Yukiura

    Full Text Available Autotaxin (ATX is a secretory protein, which converts lysophospholipids to lysophosphatidic acid (LPA, and is essential for embryonic vascular formation. ATX is abundantly detected in various biological fluids and its level is elevated in some pathophysiological conditions. However, the roles of elevated ATX levels remain to be elucidated. In this study, we generated conditional transgenic (Tg mice overexpressing ATX and examined the effects of excess LPA signalling. We found that ATX overexpression in the embryonic period caused severe vascular defects and was lethal around E9.5. ATX was conditionally overexpressed in the neonatal period using the Cre/loxP system, which resulted in a marked increase in the plasma LPA level. This resulted in retinal vascular defects including abnormal vascular plexus and increased vascular regression. Our findings indicate that the ATX level must be carefully regulated to ensure coordinated vascular formation.

  2. Autotaxin Overexpression Causes Embryonic Lethality and Vascular Defects

    Science.gov (United States)

    Yukiura, Hiroshi; Kano, Kuniyuki; Kise, Ryoji; Inoue, Asuka; Aoki, Junken

    2015-01-01

    Autotaxin (ATX) is a secretory protein, which converts lysophospholipids to lysophosphatidic acid (LPA), and is essential for embryonic vascular formation. ATX is abundantly detected in various biological fluids and its level is elevated in some pathophysiological conditions. However, the roles of elevated ATX levels remain to be elucidated. In this study, we generated conditional transgenic (Tg) mice overexpressing ATX and examined the effects of excess LPA signalling. We found that ATX overexpression in the embryonic period caused severe vascular defects and was lethal around E9.5. ATX was conditionally overexpressed in the neonatal period using the Cre/loxP system, which resulted in a marked increase in the plasma LPA level. This resulted in retinal vascular defects including abnormal vascular plexus and increased vascular regression. Our findings indicate that the ATX level must be carefully regulated to ensure coordinated vascular formation PMID:25992708

  3. Oxidative stress and vascular inflammation in aging.

    Science.gov (United States)

    El Assar, Mariam; Angulo, Javier; Rodríguez-Mañas, Leocadio

    2013-12-01

    Vascular aging, a determinant factor for cardiovascular disease and health status in the elderly, is now viewed as a modifiable risk factor. Impaired endothelial vasodilation is a early hallmark of arterial aging that precedes the clinical manifestations of vascular dysfunction, the first step to cardiovascular disease and influencing vascular outcomes in the elderly. Accordingly, the preservation of endothelial function is thought to be an essential determinant of healthy aging. With special attention on the effects of aging on the endothelial function, this review is focused on the two main mechanisms of aging-related endothelial dysfunction: oxidative stress and inflammation. Aging vasculature generates an excess of the reactive oxygen species (ROS), superoxide and hydrogen peroxide, that compromise the vasodilatory activity of nitric oxide (NO) and facilitate the formation of the deleterious radical, peroxynitrite. Main sources of ROS are mitochondrial respiratory chain and NADPH oxidases, although NOS uncoupling could also account for ROS generation. In addition, reduced antioxidant response mediated by erythroid-2-related factor-2 (Nrf2) and downregulation of mitochondrial manganese superoxide dismutase (SOD2) contributes to the establishment of chronic oxidative stress in aged vessels. This is accompanied by a chronic low-grade inflammatory phenotype that participates in defective endothelial vasodilation. The redox-sensitive transcription factor, nuclear factor-κB (NF-κB), is upregulated in vascular cells from old subjects and drives a proinflammatory shift that feedbacks oxidative stress. This chronic NF-κB activation is contributed by increased angiotensin-II signaling and downregulated sirtuins and precludes adequate cellular response to acute ROS generation. Interventions targeted to recover endogenous antioxidant capacity and cellular stress response rather than exogenous antioxidants could reverse oxidative stress-inflammation vicious cycle in

  4. Robot-Assisted Laparoscopic Partial Colpectomy and Intracorporeal Ileal Conduit Urinary Diversion (Bricker for Cervical Adenocarcinoma Recurrence

    Directory of Open Access Journals (Sweden)

    Jennifer Uzan

    2015-01-01

    Full Text Available Ileal conduit urinary diversion (Bricker is a standard surgical open procedure. The Da Vinci robot allowed precision for this surgical procedure, especially for intracorporeal suturing. Meanwhile, few reports of robot-assisted laparoscopic ileal conduit diversion (Bricker are described in the literature. We report the case of a 69-year-old patient with a vaginal recurrence of cervical adenocarcinoma associated with vesicovaginal fistula treated by robot-assisted laparoscopic partial colpectomy and ileal conduit urinary diversion (Bricker. The robot-assisted laparoscopic procedure followed all surgical steps of the open procedure. Postoperative period was free of complications.

  5. Gastric hypersecretion after formation of small bowel conduits: a common factor in several clinical states.

    Science.gov (United States)

    Forrest, J F; Longmire, W P

    1979-01-01

    As a preliminary step in studying the effect on gastric acid secretion in dogs following biliary diversion through isolated intestinal conduits, blind-ended intestinal conduits were constructed and the biliary channel was left undisturbed at this time. The results were surprising in that a significant absolute increase in gastric acid secretion occurred in all dogs, within the range of 65-286%, by merely disconnecting a segment of small bowel from the mainstream of flow of intestinal contents. This effect may be due to the "intestinal phase of gastric secretion hormone" and may in itself provide a partial explanation for the well-documented increase in gastric acid production caused by the Exalto-Mann-Williamson procedure and by choledochoenterostomy utilizing a Roux loop. PMID:426562

  6. Actively evolving subglacial conduits and eskers initiate ice shelf channels at an Antarctic grounding line

    Science.gov (United States)

    Drews, R.; Pattyn, F.; Hewitt, I. J.; Ng, F. S. L.; Berger, S.; Matsuoka, K.; Helm, V.; Bergeot, N.; Favier, L.; Neckel, N.

    2017-05-01

    Ice-shelf channels are long curvilinear tracts of thin ice found on Antarctic ice shelves. Many of them originate near the grounding line, but their formation mechanisms remain poorly understood. Here we use ice-penetrating radar data from Roi Baudouin Ice Shelf, East Antarctica, to infer that the morphology of several ice-shelf channels is seeded upstream of the grounding line by large basal obstacles indenting the ice from below. We interpret each obstacle as an esker ridge formed from sediments deposited by subglacial water conduits, and calculate that the eskers' size grows towards the grounding line where deposition rates are maximum. Relict features on the shelf indicate that these linked systems of subglacial conduits and ice-shelf channels have been changing over the past few centuries. Because ice-shelf channels are loci where intense melting occurs to thin an ice shelf, these findings expose a novel link between subglacial drainage, sedimentation and ice-shelf stability.

  7. Stability of cable-in-conduit, force-cooled conductors: elementary theory

    Energy Technology Data Exchange (ETDEWEB)

    Dresner, L.

    1979-01-01

    The recovery of cable-in-conduit conductors cooled by supercritical helium has been studied. The initial perturbation is a sudden, uniform deposition of heat. The problem has been solved, and answers have been obtained in the form of simple closed formulas under the simplifying assumption of constant thermophysical properties. Stability-optimized conductors have been identified and simple formulas for their material composition are given. A rule of design of cable-in-conduit conductors based on the existence of stability-optimized conductors is suggested. Some ''zero-flow'' experiments of Miller et al. have been analyzed, and it has been determined that for these experiments the effective heat transfer coefficient during the period of recovery is approximately 1000 Wm/sup -2/K/sup -1/.

  8. Actively evolving subglacial conduits and eskers initiate ice shelf channels at an Antarctic grounding line.

    Science.gov (United States)

    Drews, R; Pattyn, F; Hewitt, I J; Ng, F S L; Berger, S; Matsuoka, K; Helm, V; Bergeot, N; Favier, L; Neckel, N

    2017-05-09

    Ice-shelf channels are long curvilinear tracts of thin ice found on Antarctic ice shelves. Many of them originate near the grounding line, but their formation mechanisms remain poorly understood. Here we use ice-penetrating radar data from Roi Baudouin Ice Shelf, East Antarctica, to infer that the morphology of several ice-shelf channels is seeded upstream of the grounding line by large basal obstacles indenting the ice from below. We interpret each obstacle as an esker ridge formed from sediments deposited by subglacial water conduits, and calculate that the eskers' size grows towards the grounding line where deposition rates are maximum. Relict features on the shelf indicate that these linked systems of subglacial conduits and ice-shelf channels have been changing over the past few centuries. Because ice-shelf channels are loci where intense melting occurs to thin an ice shelf, these findings expose a novel link between subglacial drainage, sedimentation and ice-shelf stability.

  9. Lorentz force effect on mixed convection micropolar flow in a vertical conduit

    Science.gov (United States)

    Abdel-wahed, Mohamed S.

    2017-05-01

    The present work provides a simulation of control and filtration process of hydromagnetic blood flow with Hall current under the effect of heat source or sink through a vertical conduit (pipe). This work meets other engineering applications, such as nuclear reactors cooled during emergency shutdown, geophysical transport in electrically conducting and heat exchangers at low velocity conditions. The problem is modeled by a system of partial differential equations taking the effect of viscous dissipation, and these equations are simplified and solved analytically as a series solution using the Differential Transformation Method (DTM). The velocities and temperature profiles of the flow are plotted and discussed. Moreover, the conduit wall shear stress and heat flux are deduced and explained.

  10. Impact of the lithographic discontinuities on the karst conduit development - insights from modelling

    Science.gov (United States)

    Petrus, Karine; Szymczak, Piotr

    2016-04-01

    Karst formation is controlled by the processes of the fluid flow and reactant transport coupled to the chemical erosion of the limestone rock [1]. The coupling between these processes can lead to a number of different instabilities, resulting in the formation of dissolutional voids, caverns and conduits. Arguably the simplest systems of this kind are solution pipes, in which gravitationally driven water movement carves vertical conduits in limestone rocks. In the homogeneous rocks these conduits are often cylindrical, with almost a constant diameter along their length. However, in a stratified medium, the morphology of the pipes changes. For example, if a number of less porous layers is introduced in an otherwise homogeneous medium, then the pipes are observed to narrow as they cross the layers and then widen up to form bulbous caverns as they emerge from the layer [1]. In this communication, we investigate these effects more closely, considering different kind of lithographic discontinuities to be present in the system: the layers of increased/decreased porosity and/or permeability as well as the solubility which is different from the rest of the system. Using a Darcy-scale numerical model we analyze the effects these layers have on the shape and growth of solution pipes and compare the results on the piping morphologies observed in nature. Finally we comment on the possible relevance of these results to the cave-formation phenomena and the inception horizon concept [3]. References: 1.Howard A. D., The development of karst features, Bull. Natl. Spel. Soc. 25, 45-65 (1963) 2. Petrus, K. and Szymczak, P., Influence of layering on the formation and growth of solution pipes. Frontiers in Physics (submitted) 3.Filipponi , M., Jeannin, P. and Tacher, L., Evidence of inception horizons in karst conduit networks, Geomorphology, 106, 86-99 (2009)

  11. Structure des troupeaux et conduite de l'Elevage bovin periurbain ...

    African Journals Online (AJOL)

    urbaine de Ngaoundéré. L'objectif de l'étude était de caractériser les troupeaux bovins et d'analyser la conduite de l'élevage. Les données ont été collectées sur 83 troupeaux de zébus de race Goudali, répartis dans 3 localités. Les résultats ...

  12. Bronchovascular reconstruction with a bovine pericardial conduit and surgical reintervention due to thrombosis with revascularisation.

    Science.gov (United States)

    Peña, Emilio; Blanco, Montserrat; Otero, Teresa

    2014-01-01

    We present the case of a 57-year-old male with left hilar squamous cell carcinoma infiltrating the pulmonary artery and in whom a sleeve bronchoplasty and angioplasty were performed using a bovine pericardial conduit. Three days post-operatively, graft thrombosis was detected; thrombectomy and graft reconstruction were performed with revascularisation of the graft. Copyright © 2013 SEPAR. Published by Elsevier Espana. All rights reserved.

  13. 3D Printed Trileaflet Valve Conduits Using Biological Hydrogels and Human Valve Interstitial Cells

    OpenAIRE

    Duan, Bin; Kapetanovic, Edi; Hockaday, Laura A.; Butcher, Jonathan T.

    2013-01-01

    Tissue engineering has great potential to provide a functional de novo living valve replacement capable of integration with host tissue and growth. Among various valve conduit fabrication techniques, 3D bioprinting enables deposition of cells and hydrogels into 3D constructs with anatomical geometry and heterogeneous mechanical properties. Successful translation of this approach is however constrained by the dearth of printable and biocompatible hydrogel materials. Furthermore, it is not know...

  14. Experimental and numerical analysis of fluid flow in pipe - like conduits

    Science.gov (United States)

    Mendo-Pérez, Gerardo M.; Arciniega-Ceballos, Alejandra; Guzmán-Vázquez, José E.; Sánchez-Sesma, Francisco J.

    2017-04-01

    Volcanic activity is complex and it is a good example of multiscale phenomenon due to the sundry processes that occur at different scales while fluids ascend from the magmatic reservoirs to volcanic vents. Several processes occur at their own time scale and within a wide range of strengths. Each process contributes with its particular elastic response to the overall stress-strain field of the conduit dynamics. In this work, we present experimental and numerical analysis of fluid flowing through pipe-like conduits in order to understand the dynamic of the volcanic eruptions and its effects on the seismic signals. We focused on the elastic response of cylindrical conduits due to the flow of viscous Newtonian fluids (0.001 and 1 Pa s) passing through them. We compared signals obtained experimentally with those calculated by numerical modeling. The experimental signals are recorded with high dynamic range piezoelectric sensors located along the conduit where the fluid flows due to a sudden pressure drop. The numerical counterparts are calculated through a scheme that involves the continuity and motion equations for fluids, where the fluid couples with the surrounding solid; the excitation function simulates a pressure drop, in the range of the experimental values. In both, the excitation is considered an instantaneous pressure drop from maximum 3 bar to ambient pressure. The analysis of these observations included video recording of the process with a high speed camera. The dynamic behavior of experimental and numerical simulations present high similarity with field volcanic signals associated with pressurization processes. Our studies contributes to the understanding volcanic phenomenon and its effects on field base seismograms.

  15. 5-Hydroxymethylfurfural from black garlic extract prevents TNFα-induced monocytic cell adhesion to HUVECs by suppression of vascular cell adhesion molecule-1 expression, reactive oxygen species generation and NF-κB activation.

    Science.gov (United States)

    Kim, Hye Kyung; Choi, Young-Whan; Lee, Eun Na; Park, Jin Kyeong; Kim, Sun-Gun; Park, Da-Jung; Kim, Bong-Seon; Lim, Young-Tak; Yoon, Sik

    2011-07-01

    5-Hydroxymethylfurfural (5-HMF) is a common Maillard reaction product; the reaction occurs during heat-processing and the preparation of many types of foods and beverages. Although 5-HMF has been proposed to have harmful effects, recently, its beneficial effects, including antioxidant, cytoprotective and antitumor effects have become increasingly apparent. It was found recently that a chloroform extract of aged black garlic shows antiinflammatory properties when administered to human umbilical vein endothelial cells (HUVECs). This study investigated the antiinflammatory potential of 5-HMF purified from the chloroform extract of aged black garlic in tumor necrosis factor-α (TNF-α)-stimulated HUVECs. Treatment of HUVECs with 5-HMF strongly suppressed TNF-α-induced cell surface and total protein expression of vascular cell adhesion molecule-1 (VCAM-1) and intercellular cell adhesion molecule-1 (ICAM-1) as well as their mRNA expression. In addition, 5-HMF significantly inhibited TNF-α-induced reactive oxygen species formation, and markedly reduced THP-1 monocyte adhesion to TNF-α-stimulated HUVECs. Furthermore, 5-HMF significantly inhibited NF-κB transcription factor activation in TNF-α-stimulated HUVECs. The data provide new evidence of the antiinflammatory properties of 5-HMF in support of its potential therapeutic use for the prevention and management of vascular diseases such as atherosclerosis through mechanisms involving the inhibition of VCAM-1 expression and NF-κB activation in vascular endothelial cells. Copyright © 2011 John Wiley & Sons, Ltd.

  16. Medical Textiles as Vascular Implants and Their Success to Mimic Natural Arteries

    Directory of Open Access Journals (Sweden)

    Charanpreet Singh

    2015-06-01

    Full Text Available Vascular implants belong to a specialised class of medical textiles. The basic purpose of a vascular implant (graft and stent is to act as an artificial conduit or substitute for a diseased artery. However, the long-term healing function depends on its ability to mimic the mechanical and biological behaviour of the artery. This requires a thorough understanding of the structure and function of an artery, which can then be translated into a synthetic structure based on the capabilities of the manufacturing method utilised. Common textile manufacturing techniques, such as weaving, knitting, braiding, and electrospinning, are frequently used to design vascular implants for research and commercial purposes for the past decades. However, the ability to match attributes of a vascular substitute to those of a native artery still remains a challenge. The synthetic implants have been found to cause disturbance in biological, biomechanical, and hemodynamic parameters at the implant site, which has been widely attributed to their structural design. In this work, we reviewed the design aspect of textile vascular implants and compared them to the structure of a natural artery as a basis for assessing the level of success as an implant. The outcome of this work is expected to encourage future design strategies for developing improved long lasting vascular implants.

  17. Transcatheter Pulmonary Valve Replacement for Right Ventricular Outflow Tract Conduit Dysfunction After the Ross Procedure.

    Science.gov (United States)

    Gillespie, Matthew J; McElhinney, Doff B; Kreutzer, Jacqueline; Hellenbrand, William E; El-Said, Howaida; Ewert, Peter; Rhodes, John F; Søndergaard, Lars; Jones, Thomas K

    2015-09-01

    Right ventricular outflow tract (RVOT) conduit dysfunction is a limitation of the Ross procedure. Transcatheter pulmonary valve replacement (TPVR) could alter the impact of conduit dysfunction and the risk-benefit balance for the Ross procedure. Retrospective review of databases from 3 prospective Melody TPV (Medtronic Inc, Minneapolis, MN) trials. Among 358 patients who were catheterized with the intent to implant a Melody TPV for RVOT conduit stenosis or regurgitation (PR) as part of 3 prospective multicenter studies, 67 (19%) had a prior Ross procedure. Of these, 56 (84%) received a Melody valve; in 5 of the 11 patients who did not, the implant was aborted due to concern for coronary artery compression, and 1 implanted patient required emergent surgery for left coronary compression. The RVOT gradient decreased from a median 38 mm Hg to 13.5 mm Hg (p Freedom from TPV explant was 89% ± 5% at 4 years. Among patients who did not undergo reintervention for obstruction, there was no change in RVOT gradient over time, and all but 1 patient had mild or less PR at last follow-up. The TPVR with the Melody valve provides acceptable early outcomes and durable valve function in the majority of Ross patients. Recurrent RVOT obstruction associated with stent fracture was the main reason for reintervention. Coronary compression is not uncommon in Ross patients and should be assessed prior to TPVR. Copyright © 2015 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

  18. Optimum air-demand ratio for maximum aeration efficiency in high-head gated circular conduits.

    Science.gov (United States)

    Ozkan, Fahri; Tuna, M Cihat; Baylar, Ahmet; Ozturk, Mualla

    2014-01-01

    Oxygen is an important component of water quality and its ability to sustain life. Water aeration is the process of introducing air into a body of water to increase its oxygen saturation. Water aeration can be accomplished in a variety of ways, for instance, closed-conduit aeration. High-speed flow in a closed conduit involves air-water mixture flow. The air flow results from the subatmospheric pressure downstream of the gate. The air entrained by the high-speed flow is supplied by the air vent. The air entrained into the flow in the form of a large number of bubbles accelerates oxygen transfer and hence also increases aeration efficiency. In the present work, the optimum air-demand ratio for maximum aeration efficiency in high-head gated circular conduits was studied experimentally. Results showed that aeration efficiency increased with the air-demand ratio to a certain point and then aeration efficiency did not change with a further increase of the air-demand ratio. Thus, there was an optimum value for the air-demand ratio, depending on the Froude number, which provides maximum aeration efficiency. Furthermore, a design formula for aeration efficiency was presented relating aeration efficiency to the air-demand ratio and Froude number.

  19. Natural Occurring Silks and Their Analogues as Materials for Nerve Conduits.

    Science.gov (United States)

    Radtke, Christine

    2016-10-20

    Spider silk and its synthetic derivatives have a light weight in combination with good strength and elasticity. Their high cytocompatibility and low immunogenicity make them well suited for biomaterial products such as nerve conduits. Silk proteins slowly degrade enzymatically in vivo, thus allowing for an initial therapeutic effect such as in nerve scaffolding to facilitate endogenous repair processes, and then are removed. Silks are biopolymers naturally produced by many species of arthropods including spiders, caterpillars and mites. The silk fibers are secreted by the labial gland of the larvae of some orders of Holometabola (insects with pupa) or the spinnerets of spiders. The majority of studies using silks for biomedical applications use materials from silkworms or spiders, mostly of the genus Nephila clavipes . Silk is one of the most promising biomaterials with effects not only in nerve regeneration, but in a number of regenerative applications. The development of silks for human biomedical applications is of high scientific and clinical interest. Biomaterials in use for biomedical applications have to meet a number of requirements such as biocompatibility and elicitation of no more than a minor inflammatory response, biodegradability in a reasonable time and specific structural properties. Here we present the current status in the field of silk-based conduit development for nerve repair and discuss current advances with regard to potential clinical transfer of an implantable nerve conduit for enhancement of nerve regeneration.

  20. Preoperative imaging and prediction of oesophageal conduit necrosis after oesophagectomy for cancer.

    Science.gov (United States)

    Lainas, P; Fuks, D; Gaujoux, S; Machroub, Z; Fregeville, A; Perniceni, T; Mal, F; Dousset, B; Gayet, B

    2017-09-01

    Oesophageal conduit necrosis following oesophagectomy is a rare but life-threatening complication. The present study aimed to assess the impact of coeliac axis stenosis on outcomes after oesophagectomy for cancer. The study included consecutive patients who had an Ivor Lewis procedure with curative intent for middle- and lower-third oesophageal cancer at two tertiary referral centres. All patients underwent preoperative multidetector CT with arterial phase to detect coeliac axis stenosis. The coeliac artery was classified as normal, with extrinsic stenosis due to a median arcuate ligament or with intrinsic stenosis caused by atherosclerosis. Some 481 patients underwent an Ivor Lewis procedure. Of these, ten (2·1 per cent) developed oesophageal conduit necrosis after surgery. Coeliac artery evaluation revealed a completely normal artery in 431 patients (91·5 per cent) in the group without conduit necrosis and in one (10 per cent) with necrosis (P necrosis and five (50 per cent) with necrosis (P necrosis had a single and thin left gastric artery (P necrosis after oesophagectomy for cancer may be due to pre-existing coeliac axis stenosis. © 2017 BJS Society Ltd Published by John Wiley & Sons Ltd.

  1. Long distance seawater intrusion through a karst conduit network in the Woodville Karst Plain, Florida

    Science.gov (United States)

    Xu, Zexuan; Bassett, Seth Willis; Hu, Bill; Dyer, Scott Barrett

    2016-08-01

    Five periods of increased electrical conductivity have been found in the karst conduits supplying one of the largest first magnitude springs in Florida with water. Numerous well-developed conduit networks are distributed in the Woodville Karst Plain (WKP), Florida and connected to the Gulf of Mexico. A composite analysis of precipitation and electrical conductivity data provides strong evidence that the increases in conductivity are directly tied to seawater intrusion moving inland and traveling 11 miles against the prevailing regional hydraulic gradient from from Spring Creek Spring Complex (SCSC), a group of submarine springs at the Gulf Coast. A geochemical analysis of samples from the spring vent rules out anthropogenic contamination and upwelling regional recharge from the deep aquifer as sources of the rising conductivity. The interpretation is supported by the conceptual model established by prior researchers working to characterize the study area. This paper documents the first and longest case of seawater intrusion in the WKP, and also indicates significant possibility of seawater contamination through subsurface conduit networks in a coastal karst aquifer.

  2. Application of regression tress for prediction of water conduits failure rate

    Science.gov (United States)

    Kutyłowska, Małgorzata

    2017-11-01

    This paper presents the results of predicting the failure rate of water distribution pipes and house connections in a selected city in Poland by means of regression trees. Several regression tree models were built as part of modelling. Optimal models were selected (separately for each of the water conduit types) via an analysis of the so-called costs. The regression tree structure comprised independent variables, i.e. predictors (length, diameter, year of construction and material). The failure rates of the two types of water conduits were the dependent variable. The optimal models were characterized by the lowest costs and a relatively simple tree architecture. Operational data from the years 2001-2012 were used to determine the experimental (real) values of the failure rate and to build regression tree models. The optimal models included eight divided nodes and nine end nodes. The ranking of the significance of the parameters showed that length was the predictor responsible for division on the successive tree levels. The obtained high consistency (0.99) of the real data with the predicted ones indicates that the regression tree method can be used to analyze and assess the failure rate of water conduits.

  3. Continent catheterizable conduit for urinary diversion in children: Applicability and acceptability

    Directory of Open Access Journals (Sweden)

    Shailesh Solanki

    2015-01-01

    Full Text Available Background: Continent catheterizable conduit (CCC has made clean intermittent catheterization (CIC painless and easy. It is applicable in diverse clinical conditions. Nonetheless, convincing the parents for the need of conduit procedure is still difficult. Materials and Methods: A prospective study, included children who underwent CCC procedure from March 2008 to February 2013. The data were assessed for; diagnosis, type of conduit, number of preoperative counselling sessions before acceptance, role of "self-help group" in decision making, parental concern and satisfaction for the procedure. Results: Twenty-nine patients (males; 24, females; 5 underwent CCC procedure for various clinical conditions. The multiple preoperative counselling sessions and creation of "self-help groups" were helped them for decision making. The main concerns among parents were: (1 Impact of procedure on future fertility and sexual life. (2 Patency of native urethral channel. (3 Permanent urinary stoma over the abdomen. Conclusion: CCC procedures are applicable to a wide array of clinical situations with a good outcome. The acceptability of the CCC procedure improves with preoperative counselling of parent/child, initiation of preoperative per urethral CIC and creation of self-help groups.

  4. Long-Time Asymptotics of a Box-Type Initial Condition in a Viscous Fluid Conduit

    Science.gov (United States)

    Franco, Nevil; Webb, Emily; Maiden, Michelle; Hoefer, Mark; El, Gennady

    2017-11-01

    The initial value problem for a localized hump disturbance is fundamental to dispersive nonlinear waves, beginning with studies of the celebrated, completely integrable Korteweg-de Vries equation. However, understanding responses to similar disturbances in many realistic dispersive wave systems is more complicated because they lack the mathematical property of complete integrability. This project applies Whitham nonlinear wave modulation theory to estimate how a viscous fluid conduit evolves this classic initial value problem. Comparisons between theory, numerical simulations, and experiments are presented. The conduit system consists of a viscous fluid column (glycerol) and a diluted, dyed version of the same fluid introduced to the column through a nozzle at the bottom. Steady injection and the buoyancy of the injected fluid leads to the eventual formation of a stable fluid conduit. Within this structure, a one hump disturbance is introduced and is observed to break up into a quantifiable number of solitons. This structure's experimental evolution is to Whitham theory and numerical simulations of a long-wave interfacial model equation. The method presented is general and can be applied to other dispersive nonlinear wave systems. Please email me, as I am the submitter.

  5. Natural Occurring Silks and Their Analogues as Materials for Nerve Conduits

    Directory of Open Access Journals (Sweden)

    Christine Radtke

    2016-10-01

    Full Text Available Spider silk and its synthetic derivatives have a light weight in combination with good strength and elasticity. Their high cytocompatibility and low immunogenicity make them well suited for biomaterial products such as nerve conduits. Silk proteins slowly degrade enzymatically in vivo, thus allowing for an initial therapeutic effect such as in nerve scaffolding to facilitate endogenous repair processes, and then are removed. Silks are biopolymers naturally produced by many species of arthropods including spiders, caterpillars and mites. The silk fibers are secreted by the labial gland of the larvae of some orders of Holometabola (insects with pupa or the spinnerets of spiders. The majority of studies using silks for biomedical applications use materials from silkworms or spiders, mostly of the genus Nephila clavipes. Silk is one of the most promising biomaterials with effects not only in nerve regeneration, but in a number of regenerative applications. The development of silks for human biomedical applications is of high scientific and clinical interest. Biomaterials in use for biomedical applications have to meet a number of requirements such as biocompatibility and elicitation of no more than a minor inflammatory response, biodegradability in a reasonable time and specific structural properties. Here we present the current status in the field of silk-based conduit development for nerve repair and discuss current advances with regard to potential clinical transfer of an implantable nerve conduit for enhancement of nerve regeneration.

  6. Technique Selection of Bricker or Wallace Ureteroileal Anastomosis in Ileal Conduit Urinary Diversion: A Strategy Based on Patient Characteristics

    National Research Council Canada - National Science Library

    Liu, Longfei; Chen, Minfeng; Li, Yuan; Wang, Long; Qi, Fan; Dun, Jingeng; Chen, Jinbo; Zu, Xiongbing; Qi, Lin

    2014-01-01

    ... (Bricker and Wallace anastomosis) used in ileal conduit (IC) diversion. Patients who underwent IC diversion after radical cystectomy for transitional cell carcinoma between January 2009 and December 2011 were prospectively collected...

  7. FPGA controlled artificial vascular system

    Directory of Open Access Journals (Sweden)

    Laqua D.

    2015-09-01

    Full Text Available Monitoring the oxygen saturation of an unborn child is an invasive procedure, so far. Transabdominal fetal pulse oximetry is a promising method under research, used to estimate the oxygen saturation of a fetus noninvasively. Due to the nature of the method, the fetal information needs to be extracted from a mixed signal. To properly evaluate signal processing algorithms, a phantom modeling fetal and maternal blood circuits and tissue layers is necessary. This paper presents an improved hardware concept for an artificial vascular system, utilizing an FPGA based CompactRIO System from National Instruments. The experimental model to simulate the maternal and fetal blood pressure curve consists of two identical hydraulic circuits. Each of these circuits consists of a pre-pressure system and an artificial vascular system. Pulse curves are generated by proportional valves, separating these two systems. The dilation of the fetal and maternal artificial vessels in tissue substitutes is measured by transmissive and reflective photoplethysmography. The measurement results from the pressure sensors and the transmissive optical sensors are visualized to show the functionality of the pulse generating systems. The trigger frequency for the maternal valve was set to 1 per second, the fetal valve was actuated at 0.7 per second for validation. The reflective curve, capturing pulsations of the fetal and maternal circuit, was obtained with a high power LED (905 nm as light source. The results show that the system generates pulse curves, similar to its physiological equivalent. Further, the acquired reflective optical signal is modulated by the alternating diameter of the tubes of both circuits, allowing for tests of signal processing algorithms.

  8. Vascularized epiphyseal transplant.

    Science.gov (United States)

    Innocenti, Marco; Delcroix, Luca; Romano, G Federico; Capanna, Rodolfo

    2007-01-01

    In skeletally immature patients, the transfer of vascularized epiphysis along with a variable amount of adjoining diaphysis may provide the potential for growth of such a graft, preventing future limb length discrepancy. This article describes the authors' experience with the vascularized transfer of the proximal fibular epiphysis in the reconstruction of large bone defects including the epiphysis in a series of 27 patients ranging in age from 2 to 11 years. The follow-up, ranging from 2 to 14 years, has been long enough to allow some evaluation of the validity, indications, and limits of this reconstructive option.

  9. Enhanced noradrenergic axon regeneration into schwann cell-filled PVDF-TrFE conduits after complete spinal cord transection.

    Science.gov (United States)

    Lee, Yee-Shuan; Wu, Siliang; Arinzeh, Treena Livingston; Bunge, Mary Bartlett

    2017-02-01

    Schwann cell (SC) transplantation has been utilized for spinal cord repair and demonstrated to be a promising therapeutic strategy. In this study, we investigated the feasibility of combining SC transplantation with novel conduits to bridge the completely transected adult rat spinal cord. This is the first and initial study to evaluate the potential of using a fibrous piezoelectric polyvinylidene fluoride trifluoroethylene (PVDF-TrFE) conduit with SCs for spinal cord repair. PVDF-TrFE has been shown to enhance neurite growth in vitro and peripheral nerve repair in vivo. In this study, SCs adhered and proliferated when seeded onto PVDF-TrFE scaffolds in vitro. SCs and PVDF-TrFE conduits, consisting of random or aligned fibrous inner walls, were transplanted into transected rat spinal cords for 3 weeks to examine early repair. Glial fibrillary acidic protein (GFAP)+ astrocyte processes and GFP (green fluorescent protein)-SCs were interdigitated at both rostral and caudal spinal cord/SC transplant interfaces in both types of conduits, indicative of permissivity to axon growth. More noradrenergic/DβH+ (dopamine-beta-hydroxylase) brainstem axons regenerated across the transplant when greater numbers of GFAP+ astrocyte processes were present. Aligned conduits promoted extension of DβH+ axons and GFAP+ processes farther into the transplant than random conduits. Sensory CGRP+ (calcitonin gene-related peptide) axons were present at the caudal interface. Blood vessels formed throughout the transplant in both conduits. This study demonstrates that PVDF-TrFE conduits harboring SCs are promising for spinal cord repair and deserve further investigation. Biotechnol. Bioeng. 2017;114: 444-456. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  10. Conduit margin heating and deformation during the AD 1886 basaltic Plinian eruption at Tarawera volcano, New Zealand.

    Science.gov (United States)

    Schauroth, Jenny; Wadsworth, Fabian B; Kennedy, Ben; von Aulock, Felix W; Lavallée, Yan; Damby, David E; Vasseur, Jérémie; Scheu, Bettina; Dingwell, Donald B

    During explosive eruptions, a suspension of gas and pyroclasts rises rapidly within a conduit. Here, we have analysed textures preserved in the walls of a pyroclastic feeder dyke of the AD 1886 Tarawera basaltic Plinian fissure eruption. The samples examined consist of basaltic ash and scoria plastered onto a conduit wall of a coherent rhyolite dome and a welded rhyolitic dome breccia. We examine the textural evidence for the response of the wall material, built of ∼75 vol.% glass and ∼25 vol.% crystals (pore-free equivalent), to mass movement in the adjacent conduit. In the rhyolitic wall material, we quantify the orientation and aspect ratio of biotite crystals as strain markers of simple shear deformation, and interpret juxtaposed regions of vesiculation and vesicle collapse as evidence of conduit wall heating. Systematic changes occur close to the margin: (1) porosity is highly variable, with areas locally vesiculated or densified, (2) biotite crystals are oriented with their long axis parallel to the margin, (3) the biotites have greater aspect ratios close to the margin and (4) the biotite crystals are fractured. We interpret the biotite phenocryst deformation to result from crystal fracture, rotation and cleavage-parallel bookcase translation. These textural observations are inferred to indicate mechanical coupling between the hot gas-ash jet and the conduit wall and reheating of wall rock rhyolite. We couple these observations with a simple 1D conductive heating model to show what minimum temperature the conduit wall needs to reach in order to achieve a temperature above the glass transition throughout the texturally-defined deformed zone. We propose that conduit wall heating and resulting deformation influences conduit margin outgassing and may enhance the intensity of such large basaltic eruptions.

  11. Vascular diseases await translation of blood vessels engineered from stem cells.

    Science.gov (United States)

    Samuel, Rekha; Duda, Dan G; Fukumura, Dai; Jain, Rakesh K

    2015-10-14

    The discovery of human induced pluripotent stem cells (hiPSCs) might pave the way toward a long-sought solution for obtaining sufficient numbers of autologous cells for tissue engineering. Several methods exist for generating endothelial cells or perivascular cells from hiPSCs in vitro for use in the building of vascular tissue. We discuss current developments in the generation of vascular progenitor cells from hiPSCs and the assessment of their functional capacity in vivo, opportunities and challenges for the clinical translation of engineered vascular tissue, and modeling of vascular diseases using hiPSC-derived vascular progenitor cells. Copyright © 2015, American Association for the Advancement of Science.

  12. Transplantation of Autologous Minced Bladder Mucosa for a One-Step Reconstruction of a Tissue Engineered Bladder Conduit

    Directory of Open Access Journals (Sweden)

    Gisela Reinfeldt Engberg

    2013-01-01

    Full Text Available Surgical intervention is sometimes needed to create a conduit from the abdominal wall to the bladder for self-catheterization. We developed a method for tissue engineering a conduit for bladder emptying without in vitro cell culturing as a one-step procedure. In a porcine animal model bladder, wall tissue was excised and the mucosa was minced to small particles. The particles were attached to a tube in a 1 : 3 expansion rate with fibrin glue and transplanted back by attaching the tube to the bladder and through the abdominal wall. Sham served as controls. After 4-5 weeks, conduits were assessed in respect to macroscopic and microscopic appearance in 6 pigs. Two pigs underwent radiology before termination. Gross examination revealed a patent conduit with an opening to the bladder. Histology and immunostaining showed a multilayered transitional uroepithelium in all cases. Up to 89% of the luminal surface area was neoepithelialized but with a loose attachment to the submucosa. No epithelium was found in control animals. CT imaging revealed a patent channel that could be used for filling and emptying the bladder. Animals that experienced surgical complications did not form conduits. Minced autologous bladder mucosa can be transplanted around a tubular mold to create a conduit to the urinary bladder without in vitro culturing.

  13. Development of the Approach by States method and thermodynamical study of a 1300 MWe PWR type reactor following a complete water loss of vapor generator alimentation with the Cathare 2 code; Developpement de la conduite APE et etude thermohydraulique d'un REP 1300 MWe suite a un accident de perte totale d'eau alimentaire des generateurs de vapeur avec le code Cathare 2

    Energy Technology Data Exchange (ETDEWEB)

    Girardin, F

    1998-06-30

    The objective of this report is to study the thermohydraulic behavior of a 1300 MWe PWR type reactor for a complete loss accident in water supplying of vapor generators. The Cathare computer code has been used in this aim. (N.C.)

  14. A Role for the Endothelium in Vascular Calcification

    Science.gov (United States)

    Yao, Yucheng; Jumabay, Medet; Ly, Albert; Radparvar, Melina; Cubberly, Mark R.; Boström, Kristina I.

    2013-01-01

    Rationale Vascular calcification is a regulated process that involves osteoprogenitor cells and frequently complicates common vascular disease such as atherosclerosis and diabetic vasculopathy. However, it is not clear if the vascular endothelium has a role in contributing osteoprogenitor cells to the calcific lesions. Objective To determine if the vascular endothelium contributes osteoprogenitor cells to vascular calcification. Methods and Results In this study, we use two mouse models of vascular calcification, mice with gene deletion of matrix Gla protein (MGP), a BMP-inhibitor, and Ins2Akita/+ mice, a diabetes model. We show that enhanced bone morphogenetic protein (BMP) signaling in both types of mice stimulates the vascular endothelium to contribute osteoprogenitor cells to the vascular calcification. The enhanced BMP signaling results in endothelial-mesenchymal transitions and the emergence of multipotent cells, followed by osteoinduction. Endothelial markers co-localize with multipotent and osteogenic markers in calcified arteries by immunostaining and fluorescence-activated cell sorting. Lineage tracing using Tie2-Gfp transgenic mice supports an endothelial origin of the osteogenic cells. Enhancement of MGP expression in Ins2Akita/+ mice, as mediated by an Mgp transgene limits the generation of multipotent cells. Moreover, MGP-depleted human aortic endothelial cells in vitro acquire multipotency rendering the cells susceptible to osteoinduction by BMP and high glucose. Conclusions Our data suggest that the endothelium is a source of osteoprogenitor cells in vascular calcification that occurs in disorders with high BMP activation such as deficiency of BMP inhibitors and diabetes. PMID:23852538

  15. Gas slug rise in open versus plugged basaltic conduits: the transition from Strombolian to sustained volcanic eruptions

    Science.gov (United States)

    Llewellin, Ed; Mathias, Simon; Del Bello, Elisabetta; Lane, Steve; Taddeucci, Jacopo

    2010-05-01

    Strombolian eruptions are characterized by low-energy explosive activity, which may repeat, at fairly regular intervals, for long periods of time. Explosions at the vent are thought to result from the arrival of discrete slugs of magmatic gas that have risen through the magmatic plumbing system. We develop a one dimensional, analytical model of gas slug rise in a volcanic conduit which we use to investigate the controls on the dynamics of Strombolian eruptions. We consider a partially-filled, cylindrical conduit containing degassed magma, that is initially in magma-static equilibrium with a constant pressure magma reservoir at depth. We introduce a slug of gas at the base of the conduit and consider the temporal evolution of the pressure distribution in the conduit, and the motion of the magma above and below the slug, as the slug rises, decompresses, and expands isothermally. We validate our model against published data for gas slugs rising and decompressing in a vertical pipe [James et al., 2008, Geological Society of London, Special Publications 307, 147-167] by imposing the condition of zero magma-flux at the base of the conduit, and constant pressure at the top; we find excellent agreement. If we impose the more geologically-sound condition of constant pressure at the base of the conduit, we can consider two scenarios of volcanological relevance: 1) Vent plugged with cooler, more-viscous magma. In this case, as the slug rises and expands beneath the plug, it pushes the degassed magma below it down the conduit, consequently, magma re-enters the chamber from the base of the conduit. The slug reaches the viscous plug at the top of the conduit with a significant over-pressure; this may be sufficient to disrupt the plug, causing a Strombolian explosion, or the gas may percolate away. Fresh magma then moves up from the chamber, into the conduit to restore magma-static equilibrium. 2) Open vent. As the slug rises and expands, the volume of magma held in the falling

  16. Hypercholesterolaemia and vascular dementia.

    Science.gov (United States)

    Appleton, Jason P; Scutt, Polly; Sprigg, Nikola; Bath, Philip M

    2017-07-15

    Vascular dementia (VaD) is the second commonest cause of dementia. Stroke is the leading cause of disability in adults in developed countries, the second major cause of dementia and the third commonest cause of death. Traditional vascular risk factors-diabetes, hypercholesterolaemia, hypertension and smoking-are implicated as risk factors for VaD. The associations between cholesterol and small vessel disease (SVD), stroke, cognitive impairment and subsequent dementia are complex and as yet not fully understood. Similarly, the effects of lipids and lipid-lowering therapy on preventing or treating dementia remain unclear; the few trials that have assessed lipid-lowering therapy for preventing (two trials) or treating (four trials) dementia found no evidence to support the use of lipid-lowering therapy for these indications. It is appropriate to treat those patients with vascular risk factors that meet criteria for lipid-lowering therapy for the primary and secondary prevention of cardiovascular and cerebrovascular events, and in line with current guidelines. Managing the individual patient in a holistic manner according to his or her own vascular risk profile is recommended. Although the paucity of randomized controlled evidence makes for challenging clinical decision making, it provides multiple opportunities for on-going and future research, as discussed here. © 2017 The Author(s).

  17. Depression in vascular dementia.

    NARCIS (Netherlands)

    Naarding, P.; Koning, I. de; Kooten, F. van; Dippel, D.W.; Janzing, J.G.E.; Mast, R.C. van der; Koudstaal, P.J.

    2003-01-01

    OBJECTIVE: To study the presence of different dimensions of depression in subjects with vascular dementia. BACKGROUND: After a stroke, cognitive, affective and behavioural disturbances are common. It has been suggested that the nature of affective symptomatology can help to differentiate organic

  18. Vascular management in rotationplasty.

    Science.gov (United States)

    Mahoney, Craig R; Hartman, Curtis W; Simon, Pamela J; Baxter, B Timothy; Neff, James R

    2008-05-01

    The Van Nes rotationplasty is a useful limb-preserving procedure for skeletally immature patients with distal femoral or proximal tibial malignancy. The vascular supply to the lower limb either must be maintained and rotated or transected and reanastomosed. We asked whether there would be any difference in the ankle brachial index or complication rate for the two methods of vascular management. Vessels were resected with the tumor in seven patients and preserved and rotated in nine patients. One amputation occurred in the group in which the vessels were preserved. Four patients died secondary to metastatic disease diagnosed preoperatively. The most recent ankle brachial indices were 0.96 and 0.82 for the posterior tibial and dorsalis pedis arteries, respectively, in the reconstructed group. The ankle brachial indices were 0.98 and 0.96 for the posterior tibial and dorsalis pedis arteries, respectively, in the rotated group. Outcomes appear similar using both methods of vascular management and one should not hesitate to perform an en bloc resection when there is a question of vascular involvement.

  19. Renal posttransplant's vascular complications

    Directory of Open Access Journals (Sweden)

    Bašić Dragoslav

    2003-01-01

    Full Text Available INTRODUCTION Despite high graft and recipient survival figures worldwide today, a variety of technical complications can threaten the transplant in the postoperative period. Vascular complications are commonly related to technical problems in establishing vascular continuity or to damage that occurs during donor nephrectomy or preservation [13]. AIM The aim of the presenting study is to evaluate counts and rates of vascular complications after renal transplantation and to compare the outcome by donor type. MATERIAL AND METHODS A total of 463 kidneys (319 from living related donor LD and 144 from cadaveric donor - CD were transplanted during the period between June 1975 and December 1998 at the Urology & Nephrology Institute of Clinical Centre of Serbia in Belgrade. Average recipients' age was 33.7 years (15-54 in LD group and 39.8 (19-62 in CD group. Retrospectively, we analyzed medical records of all recipients. Statistical analysis is estimated using Hi-squared test and Fischer's test of exact probability. RESULTS Major vascular complications including vascular anastomosis thrombosis, internal iliac artery stenosis, internal iliac artery rupture obliterant vasculitis and external iliac vein rupture were analyzed. In 25 recipients (5.4% some of major vascular complications were detected. Among these cases, 22 of them were from CD group vs. three from LD group. Relative rate of these complications was higher in CD group vs. LD group (p<0.0001. Among these complications dominant one was vascular anastomosis thrombosis which occurred in 18 recipients (17 from CD vs. one from LD. Of these recipients 16 from CD lost the graft, while the rest of two (one from each group had lethal outcome. DISCUSSION Thrombosis of renal allograft vascular anastomosis site is the most severe complication following renal transplantation. In the literature, renal allograft thrombosis is reported with different incidence rates, from 0.5-4% [14, 15, 16]. Data from the

  20. Vascular manifestations of Behcet's disease

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    Regina Georgiyeva Goloeva

    2010-01-01

    Conclusion. Vascular disorders in BD were diagnosed in one fourth of the patients, mainly in young male patients. Severe thromboses with the development of chronic venous insignificance, Budd-Chiari syndrome, pulmonary and iliac artery aneurysms, and arterial thromboses were observed in male patients only. Vascular events were associated with erythema nodosum and epididymitis; in these concomitances, the vascular risk was substantially increased. Vascular death rates were 2,2%.

  1. Engineering vascularized skeletal muscle tissue

    NARCIS (Netherlands)

    Levenberg, Shulamit; Rouwkema, Jeroen; Macdonald, Mara; Garfein, Evan S.; Kohane, Daniel S.; Darland, Diane C.; Marini, Robert; van Blitterswijk, Clemens; Mulligan, Richard C.; D'Amore, Patricia A.; Langer, Robert

    2005-01-01

    One of the major obstacles in engineering thick, complex tissues such as muscle is the need to vascularize the tissue in vitro. Vascularization in vitro could maintain cell viability during tissue growth, induce structural organization and promote vascularization upon implantation. Here we describe

  2. The Vascular Depression Hypothesis: Mechanisms Linking Vascular Disease with Depression

    Science.gov (United States)

    Taylor, Warren D.; Aizenstein, Howard J.; Alexopoulos, George S.

    2013-01-01

    The ‘Vascular Depression’ hypothesis posits that cerebrovascular disease may predispose, precipitate, or perpetuate some geriatric depressive syndromes. This hypothesis stimulated much research that has improved our understanding of the complex relationships between late-life depression (LLD), vascular risk factors, and cognition. Succinctly, there are well-established relationships between late-life depression, vascular risk factors, and cerebral hyperintensities, the radiological hallmark of vascular depression. Cognitive dysfunction is common in late-life depression, particularly executive dysfunction, a finding predictive of poor antidepressant response. Over time, progression of hyperintensities and cognitive deficits predicts a poor course of depression and may reflect underlying worsening of vascular disease. This work laid the foundation for examining the mechanisms by which vascular disease influences brain circuits and influences the development and course of depression. We review data testing the vascular depression hypothesis with a focus on identifying potential underlying vascular mechanisms. We propose a disconnection hypothesis, wherein focal vascular damage and white matter lesion location is a crucial factor influencing neural connectivity that contributes to clinical symptomatology. We also propose inflammatory and hypoperfusion hypotheses, concepts that link underlying vascular processes with adverse effects on brain function that influence the development of depression. Testing such hypotheses will not only inform the relationship between vascular disease and depression but also provide guidance on the potential repurposing of pharmacological agents that may improve late-life depression outcomes. PMID:23439482

  3. Confort 15 model of conduit dynamics: applications to Pantelleria Green Tuff and Etna 122 BC eruptions

    Science.gov (United States)

    Campagnola, S.; Romano, C.; Mastin, L. G.; Vona, A.

    2016-06-01

    Numerical simulations are useful tools to illustrate how flow parameters and physical processes may affect eruption dynamics of volcanoes. In this paper, we present an updated version of the Conflow model, an open-source numerical model for flow in eruptive conduits during steady-state pyroclastic eruptions (Mastin and Ghiorso in A numerical program for steady-state flow of magma-gas mixtures through vertical eruptive conduits. U.S. Geological Survey Open File Report 00-209, 2000). In the modified version, called Confort 15, the rheological constraints are improved, incorporating the most recent constitutive equations of both the liquid viscosity and crystal-bearing rheology. This allows all natural magma compositions, including the peralkaline melts excluded in the original version, to be investigated. The crystal-bearing rheology is improved by computing the effect of strain rate and crystal shape on the rheology of natural magmatic suspensions and expanding the crystal content range in which rheology can be modeled compared to the original version ( Conflow is applicable to magmatic mixtures with up to 30 vol% crystal content). Moreover, volcanological studies of the juvenile products (crystal and vesicle size distribution) of the investigated eruption are directly incorporated into the modeling procedure. Vesicle number densities derived from textural analyses are used to calculate, through Toramaru equations, maximum decompression rates experienced during ascent. Finally, both degassing under equilibrium and disequilibrium conditions are considered. This allows considerations on the effect of different fragmentation criteria on the conduit flow analyses, the maximum volume fraction criterion ("porosity criterion"), the brittle fragmentation criterion and the overpressure fragmentation criterion. Simulations of the pantelleritic and trachytic phases of the Green Tuff (Pantelleria) and of the Plinian Etna 122 BC eruptions are performed to test the upgrades in

  4. Numerical modeling and sensitivity analysis of seawater intrusion in a dual-permeability coastal karst aquifer with conduit networks

    Directory of Open Access Journals (Sweden)

    Z. Xu

    2018-01-01

    Full Text Available Long-distance seawater intrusion has been widely observed through the subsurface conduit system in coastal karst aquifers as a source of groundwater contaminant. In this study, seawater intrusion in a dual-permeability karst aquifer with conduit networks is studied by the two-dimensional density-dependent flow and transport SEAWAT model. Local and global sensitivity analyses are used to evaluate the impacts of boundary conditions and hydrological characteristics on modeling seawater intrusion in a karst aquifer, including hydraulic conductivity, effective porosity, specific storage, and dispersivity of the conduit network and of the porous medium. The local sensitivity analysis evaluates the parameters' sensitivities for modeling seawater intrusion, specifically in the Woodville Karst Plain (WKP. A more comprehensive interpretation of parameter sensitivities, including the nonlinear relationship between simulations and parameters, and/or parameter interactions, is addressed in the global sensitivity analysis. The conduit parameters and boundary conditions are important to the simulations in the porous medium because of the dynamical exchanges between the two systems. The sensitivity study indicates that salinity and head simulations in the karst features, such as the conduit system and submarine springs, are critical for understanding seawater intrusion in a coastal karst aquifer. The evaluation of hydraulic conductivity sensitivity in the continuum SEAWAT model may be biased since the conduit flow velocity is not accurately calculated by Darcy's equation as a function of head difference and hydraulic conductivity. In addition, dispersivity is no longer an important parameter in an advection-dominated karst aquifer with a conduit system, compared to the sensitivity results in a porous medium aquifer. In the end, the extents of seawater intrusion are quantitatively evaluated and measured under different scenarios with the variabilities of

  5. Numerical modeling and sensitivity analysis of seawater intrusion in a dual-permeability coastal karst aquifer with conduit networks

    Science.gov (United States)

    Xu, Zexuan; Hu, Bill X.; Ye, Ming

    2018-01-01

    Long-distance seawater intrusion has been widely observed through the subsurface conduit system in coastal karst aquifers as a source of groundwater contaminant. In this study, seawater intrusion in a dual-permeability karst aquifer with conduit networks is studied by the two-dimensional density-dependent flow and transport SEAWAT model. Local and global sensitivity analyses are used to evaluate the impacts of boundary conditions and hydrological characteristics on modeling seawater intrusion in a karst aquifer, including hydraulic conductivity, effective porosity, specific storage, and dispersivity of the conduit network and of the porous medium. The local sensitivity analysis evaluates the parameters' sensitivities for modeling seawater intrusion, specifically in the Woodville Karst Plain (WKP). A more comprehensive interpretation of parameter sensitivities, including the nonlinear relationship between simulations and parameters, and/or parameter interactions, is addressed in the global sensitivity analysis. The conduit parameters and boundary conditions are important to the simulations in the porous medium because of the dynamical exchanges between the two systems. The sensitivity study indicates that salinity and head simulations in the karst features, such as the conduit system and submarine springs, are critical for understanding seawater intrusion in a coastal karst aquifer. The evaluation of hydraulic conductivity sensitivity in the continuum SEAWAT model may be biased since the conduit flow velocity is not accurately calculated by Darcy's equation as a function of head difference and hydraulic conductivity. In addition, dispersivity is no longer an important parameter in an advection-dominated karst aquifer with a conduit system, compared to the sensitivity results in a porous medium aquifer. In the end, the extents of seawater intrusion are quantitatively evaluated and measured under different scenarios with the variabilities of important parameters

  6. Impact of pacing modality and biventricular pacing on cardiac output and coronary conduit flow in the post-cardiotomy patient.

    LENUS (Irish Health Repository)

    Healy, David G

    2012-02-03

    We have previously demonstrated the role of univentricular pacing modalities in influencing coronary conduit flow in the immediate post-operative period in the cardiac surgery patient. We wanted to determine the mechanism of this improved coronary conduit and, in addition, to explore the possible benefits with biventricular pacing. Sixteen patients undergoing first time elective coronary artery bypass grafting who required pacing following surgery were recruited. Comparison of cardiac output and coronary conduit flow was performed between VVI and DDD pacing with a single right ventricular lead and biventricular pacing lead placement. Cardiac output was measured using arterial pulse waveform analysis while conduit flow was measured using ultrasonic transit time methodology. Cardiac output was greatest with DDD pacing using right ventricular lead placement only [DDD-univentricular 5.42 l (0.7), DDD-biventricular 5.33 l (0.8), VVI-univentricular 4.71 l (0.8), VVI-biventricular 4.68 l (0.6)]. DDD-univentricular pacing was significantly better than VVI-univentricular (P=0.023) and VVI-biventricular pacing (P=0.001) but there was no significant advantage to DDD-biventricular pacing (P=0.45). In relation to coronary conduit flow, DDD pacing again had the highest flow [DDD-univentricular 55 ml\\/min (24), DDD-biventricular 52 ml\\/min (25), VVI-univentricular 47 ml\\/min (23), VVI-biventricular 50 ml\\/min (26)]. DDD-univentricular pacing was significantly better than VVI-univentricular (P=0.006) pacing but not significantly different to VVI-biventricular pacing (P=0.109) or DDD-biventricular pacing (P=0.171). Pacing with a DDD modality offers the optimal coronary conduit flow by maximising cardiac output. Biventricular lead placement offered no significant benefit to coronary conduit flow or cardiac output.

  7. Preparation and evaluation of novel nano-bioglass/gelatin conduit for peripheral nerve regeneration.

    Science.gov (United States)

    Koudehi, Masoumeh Foroutan; Fooladi, Abbas Ali Imani; Mansoori, Kourosh; Jamalpoor, Zahra; Amiri, Afsaneh; Nourani, Mohammad Reza

    2014-02-01

    Peripheral nerves are exposed to physical injuries usually caused by trauma that may lead to a significant loss of sensory or motor functions and is considered as a serious health problem for societies today. This study was designed to develop a novel nano bioglass/gelatin conduit (BGGC) for the peripheral nerve regeneration. The bioglass nanoparticles were prepared by sol-gel technique and characterized using transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction analysis. The interfacial bonding interaction between the nano-bioglass and gelatin in the developed conduits was assessed by FTIR. The surface morphology and pore size of the nanocomposite were investigated through scanning electron microscopy with the pore size of the conduits being 10-40 μm. Biocompatibility was assessed by MTT assay which indicated the BGGC to have good cytocompatibility. The guidance channel was examined and used to regenerate a 10 mm gap in the right sciatic nerve of a male Wistar rat. Twenty rats were randomly divided into two experimental groups, one with the BGGC and the other being normal rats. The gastrocnemius muscle contractility was also examined at one, two and three months post-surgery in all groups using electromyography (EMAP). Histological and functional evaluation and the results obtained from electromyography indicated that at three months, nerve regeneration of the BGGC group was statistically equivalent to the normal group (p > 0.05). Our result suggests that the BGGC can be a suitable candidate for peripheral nerve repair.

  8. A robotic approach to mapping post-eruptive volcanic fissure conduits

    Science.gov (United States)

    Parcheta, Carolyn E.; Pavlov, Catherine A.; Wiltsie, Nicholas; Carpenter, Kalind C.; Nash, Jeremy; Parness, Aaron; Mitchell, Karl L.

    2016-06-01

    VolcanoBot was developed to map volcanic vents and their underlying conduit systems, which are rarely preserved and generally inaccessible to human exploration. It uses a PrimeSense Carmine 1.09 sensor for mapping and carries an IR temperature sensor, analog distance sensor, and an inertial measurement unit (IMU) inside a protective shell. The first field test succeeded in collecting valuable scientific data but revealed several needed improvements, including more rugged cable connections and mechanical couplers, increased ground clearance, and higher-torque motors for uphill mobility. The second field test significantly improved on all of these aspects but it traded electrical ruggedness for reduced data collection speed. Data collected by the VolcanoBots, while intermittent, yield the first insights into the cm-scale geometry of volcanic fissures at depths of up to 25 m. VolcanoBot was deployed at the 1969 Mauna Ulu fissure system on Kīlauea volcano in Hawai'i. It collected first-of-its-kind data from inside the fissure system. We hypothesized that 1) fissure sinuosity should decrease with depth, 2) irregularity should be persistent with depth, 3) any blockages in the conduit should occur at the narrowest points, and 4) the fissure should narrow with depth until it is too narrow for VolcanoBot to pass or is plugged with solidified lava. Our field campaigns did not span enough lateral or vertical area to test sinuosity. The preliminary data indicate that 1) there were many irregularities along fissures at depth, 2) blockages occurred, but not at obviously narrow locations, and 3) the conduit width remained a consistent 0.4-0.5 m for most of the upper 10 m that we analyzed.

  9. Flambage vertical des conduites en souillées Vertical Buckling of Buried Pipes

    Directory of Open Access Journals (Sweden)

    Bournazel C.

    2006-11-01

    Full Text Available Si l'apparition d'un flambage vertical des conduites rigides enfouies dans une tranchée est un phénomène assez rare, il peut ne pas en être de même pour des conduites flexibles dont les propriétés mécaniques sont de nature différente. Une étude théorique et expérimentale, ayant pour but de proposer une méthode analytique de calcul de l'apparition du flambage et de son évolution sous l'effet de la pression interne, a été réalisée. II apparaît que les conduites flexibles actuelles sont très sensibles à ce phénomène et qu'il serait nécessaire, pour l'éliminer à coup sûr, de réexaminer la structure des flexibles ou d'imaginer des artifices dans la procédure d'ensouillage Whereas the appearance of vertical buckling in rigid pipes buried in a trench is a relatively rare phenomenon, the same cannot be said for flexible pipes which have mechanical properties of a different nature. A theoretical and experimental study has been made with the aim of proposing an analytical method for computing the appearance of buckling and its evolution under the effect of outside pressure. Current flexible pipes appear to be very sensitive to this phenomenon, and to be certain of eliminating it the structure of flexible pipes should be reexamined or stratagems in the burying procedure should be devised.

  10. Visualized Evaluation of Blood Flow to the Gastric Conduit and Complications in Esophageal Reconstruction.

    Science.gov (United States)

    Noma, Kazuhiro; Shirakawa, Yasuhiro; Kanaya, Nobuhiko; Okada, Tsuyoshi; Maeda, Naoaki; Ninomiya, Takayuki; Tanabe, Shunsuke; Sakurama, Kazufumi; Fujiwara, Toshiyoshi

    2018-03-01

    Evaluation of the blood supply to gastric conduits is critically important to avoid complications after esophagectomy. We began visual evaluation of blood flow using indocyanine green (ICG) fluorescent imaging in July 2015, to reduce reconstructive complications. In this study, we aimed to statistically verify the efficacy of blood flow evaluation using our simplified ICG method. A total of 285 consecutive patients who underwent esophagectomy and gastric conduit reconstruction were reviewed and divided into 2 groups: before and after introduction of ICG evaluation. The entire cohort and 68 patient pairs after propensity score matching (PS-M) were evaluated for clinical outcomes and the effect of visualized evaluation on reducing the risk of complication. The leakage rate in the ICG group was significantly lower than in the non-ICG group for each severity grade, both in the entire cohort (285 subjects) and after PS-M; the rates of other major complications, including recurrent laryngeal nerve palsy and pneumonia, were not different. The duration of postoperative ICU stay was approximately 1 day shorter in the ICG group than in the non-ICG group in the entire cohort, and approximately 2 days shorter after PS-M. Visualized evaluation of blood flow with ICG methods significantly reduced the rate of anastomotic complications of all Clavien-Dindo (CD) grades. Odds ratios for ICG evaluation decreased with CD grade (0.3419 for CD ≥ 1; 0.241 for CD ≥ 2; and 0.2153 for CD ≥ 3). Objective evaluation of blood supply to the reconstructed conduit using ICG fluorescent imaging reduces the risk and degree of anastomotic complication. Copyright © 2017 American College of Surgeons. Published by Elsevier Inc. All rights reserved.

  11. Orientated Guidance of Peripheral Nerve Regeneration Using Conduits with a Microtube Array Sheet (MTAS).

    Science.gov (United States)

    Wang, Yueming; Wang, Wenjin; Wo, Yan; Gui, Ting; Zhu, Hao; Mo, Xiumei; Chen, Chien-Chung; Li, Qingfeng; Ding, Wenlong

    2015-04-29

    Material surface topography has been shown to affect the biological behavior of cells in vitro; however, the in vivo effect on peripheral nerve regeneration has not been explored. Here, we studied the potential of a microtube array sheet (MTAS) with a unique longitudinal surface topography to promote peripheral nerve regeneration efficiency, both in vivo and in vitro. Schwann cells, spinal cord motor neurons, and dorsal root ganglion neurons were seeded on the MTAS to study the effect of the construct on the biological properties and behaviors of neural cells. The MTAS guided the oriented migration of Schwann cells without affecting other critical biological properties, such as proliferation and neurotrophin expression. In addition, the MTAS guided the directed extension of neurites from both types of neurons. Next, we tested the capability of the MTAS to facilitate peripheral nerve regeneration by bridging a 10 mm sciatic nerve defect in rats with a nerve conduit equipped with an MTAS lining. The MTAS significantly promoted peripheral nerve regeneration, as suggested by the greater fiber caliber in the midconduit and the greater abundance of fibers in nerve segment distal to the conduit. Moreover, scanning electron microscopy (SEM) analysis suggested the orientated guidance of nerve regeneration by the MTAS, as indicated by the smaller eccentricity of the nerve fibers and the concordant arrangement of the collagen fiber in both the fibers and the matrix in the MTAS group. Our results collectively suggest that the conduits with the MTAS developed in this study have significant potential for facilitating peripheral nerve regeneration by modifying critical biological behaviors and guiding orientated nerve growth.

  12. Aortic bypass surgery using synthetic conduits in a child with mycotic aneurysmal disease.

    Science.gov (United States)

    Sayed, A; Mashaal, M; Soliman, S A; Elwan, H

    2016-04-01

    A six-year-old child developed multiple aortic aneurysms as a consequence of fungal infection following thoracic aortic surgery for coarctation. Several repairs of both the thoracic and abdominal aorta were carried out using synthetic material combined with long-term postoperative antifungal treatment. We describe the surgical interventions performed and follow-up. The choice of conduit continues to be the main concern; however, when other alternatives are not available, synthetic material combined with indefinite antifungal treatment can produce satisfactory medium-term results.

  13. Systems and methods for coating conduit interior surfaces utilizing a thermal spray gun with extension arm

    Science.gov (United States)

    Moore, Karen A.; Zatorski, Raymond A.

    2005-07-12

    Systems and methods for applying a coating to an interior surface of a conduit. In one embodiment, a spray gun configured to apply a coating is attached to an extension arm which may be inserted into the bore of a pipe. The spray gun may be a thermal spray gun adapted to apply a powder coating. An evacuation system may be used to provide a volume area of reduced air pressure for drawing overspray out of the pipe interior during coating. The extension arm as well as the spray gun may be cooled to maintain a consistent temperature in the system, allowing for more consistent coating.

  14. Brain Vascular Imaging Techniques

    Directory of Open Access Journals (Sweden)

    Bàrbara Laviña

    2016-12-01

    Full Text Available Recent major improvements in a number of imaging techniques now allow for the study of the brain in ways that could not be considered previously. Researchers today have well-developed tools to specifically examine the dynamic nature of the blood vessels in the brain during development and adulthood; as well as to observe the vascular responses in disease situations in vivo. This review offers a concise summary and brief historical reference of different imaging techniques and how these tools can be applied to study the brain vasculature and the blood-brain barrier integrity in both healthy and disease states. Moreover, it offers an overview on available transgenic animal models to study vascular biology and a description of useful online brain atlases.

  15. Plant Vascular Biology 2010

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Biao

    2014-11-17

    This grant supported the Second International Conference on Plant Vascular Biology (PVB 2010) held July 24-28, 2010 on the campus of Ohio State University, Columbus, Ohio. Biao Ding (Ohio State University; OSU) and David Hannapel (Iowa State University; ISU) served as co-chairs of this conference. Biao Ding served as the local organizer. PVB is defined broadly here to include studies on the biogenesis, structure and function of transport systems in plants, under conditions of normal plant growth and development as well as of plant interactions with pathogens. The transport systems cover broadly the xylem, phloem, plasmodesmata and vascular cell membranes. The PVB concept has emerged in recent years to emphasize the integrative nature of the transport systems and approaches to investigate them.

  16. Pathophysiology of vascular dementia

    Directory of Open Access Journals (Sweden)

    Rizzo Claudia

    2009-11-01

    Full Text Available Abstract The concept of Vascular Dementia (VaD has been recognized for over a century, but its definition and diagnostic criteria remain unclear. Conventional definitions identify the patients too late, miss subjects with cognitive impairment short of dementia, and emphasize consequences rather than causes, the true bases for treatment and prevention. We should throw out current diagnostic categories and describe cognitive impairment clinically and according to commonly agreed instruments that document the demographic data in a standardized manner and undertake a systematic effort to identify the underlying aetiology in each case. Increased effort should be targeted towards the concept of and criteria for Vascular Cognitive Impairment and Post-Stroke Dementia as well as for genetic factors involved, especially as these categories hold promise for early prevention and treatment.

  17. Vascular cognitive impairment

    Directory of Open Access Journals (Sweden)

    N.V. Vakhnina

    2014-01-01

    Full Text Available Vascular pathology of the brain is the second most common cause of cognitive impairment after Alzheimer's disease. The article describes the modern concepts of etiology, pathogenetic mechanisms, clinical features and approaches to diagnosis and therapy of vascular cognitive impairment (VCI. Cerebrovascular accident, chronic cerebral circulatory insufficiency and their combination, sometimes in combination with a concomitant neurodegenerative process, are shown to be the major types of brain lesions leading to VCI. The clinical presentation of VCI is characterized by the neuropsychological status dominated by impairment of the executive frontal functions (planning, control, attention in combination with focal neurological symptoms. The diagnosis is based on comparing of the revealed neuropsychological and neurological features with neuroimaging data. Neurometabolic, acetylcholinergic, glutamatergic, and other vasoactive drugs and non-pharmacological methods are widely used to treat VCI. 

  18. Lysophosphatidic acid targets vascular and oncogenic pathways via RAGE signaling

    Science.gov (United States)

    Touré, Fatouma; Chitayat, Seth; Pei, Renjun; Song, Fei; Li, Qing; Zhang, Jinghua; Rosario, Rosa; Ramasamy, Ravichandran; Chazin, Walter J.

    2012-01-01

    The endogenous phospholipid lysophosphatidic acid (LPA) regulates fundamental cellular processes such as proliferation, survival, motility, and invasion implicated in homeostatic and pathological conditions. Hence, delineation of the full range of molecular mechanisms by which LPA exerts its broad effects is essential. We report avid binding of LPA to the receptor for advanced glycation end products (RAGE), a member of the immunoglobulin superfamily, and mapping of the LPA binding site on this receptor. In vitro, RAGE was required for LPA-mediated signal transduction in vascular smooth muscle cells and C6 glioma cells, as well as proliferation and migration. In vivo, the administration of soluble RAGE or genetic deletion of RAGE mitigated LPA-stimulated vascular Akt signaling, autotaxin/LPA-driven phosphorylation of Akt and cyclin D1 in the mammary tissue of transgenic mice vulnerable to carcinogenesis, and ovarian tumor implantation and development. These findings identify novel roles for RAGE as a conduit for LPA signaling and suggest targeting LPA–RAGE interaction as a therapeutic strategy to modify the pathological actions of LPA. PMID:23209312

  19. Pathophysiology of vascular dementia

    OpenAIRE

    Rizzo Claudia; Duro Giovanni; Iemolo Francesco; Castiglia Laura; Hachinski Vladimir; Caruso Calogero

    2009-01-01

    Abstract The concept of Vascular Dementia (VaD) has been recognized for over a century, but its definition and diagnostic criteria remain unclear. Conventional definitions identify the patients too late, miss subjects with cognitive impairment short of dementia, and emphasize consequences rather than causes, the true bases for treatment and prevention. We should throw out current diagnostic categories and describe cognitive impairment clinically and according to commonly agreed instruments th...

  20. Pulmonary vascular imaging

    Energy Technology Data Exchange (ETDEWEB)

    Fedullo, P.F.; Shure, D.

    1987-03-01

    A wide range of pulmonary vascular imaging techniques are available for the diagnostic evaluation of patients with suspected pulmonary vascular disease. The characteristics of any ideal technique would include high sensitivity and specificity, safety, simplicity, and sequential applicability. To date, no single technique meets these ideal characteristics. Conventional pulmonary angiography remains the gold standard for the diagnosis of acute thromboembolic disease despite the introduction of newer techniques such as digital subtraction angiography and magnetic resonance imaging. Improved noninvasive lower extremity venous testing methods, particularly impedance plethysmography, and ventilation-perfusion scanning can play significant roles in the noninvasive diagnosis of acute pulmonary emboli when properly applied. Ventilation-perfusion scanning may also be useful as a screening test to differentiate possible primary pulmonary hypertension from chronic thromboembolic pulmonary hypertension. And, finally, angioscopy may be a useful adjunctive technique to detect chronic thromboembolic disease and determine operability. Optimal clinical decision-making, however, will continue to require the proper interpretation of adjunctive information obtained from the less-invasive techniques, applied with an understanding of the natural history of the various forms of pulmonary vascular disease and with a knowledge of the capabilities and shortcomings of the individual techniques.

  1. Update on Vascular Dementia.

    Science.gov (United States)

    Khan, Ayesha; Kalaria, Raj N; Corbett, Anne; Ballard, Clive

    2016-09-01

    Vascular dementia (VaD) is a major contributor to the dementia syndrome and is described as having problems with reasoning, planning, judgment, and memory caused by impaired blood flow to the brain and damage to the blood vessels resulting from events such as stroke. There are a variety of etiologies that contribute to the development of vascular cognitive impairment and VaD, and these are often associated with other dementia-related pathologies such as Alzheimer disease. The diagnosis of VaD is difficult due to the number and types of lesions and their locations in the brain. Factors that increase the risk of vascular diseases such as stroke, high blood pressure, high cholesterol, and smoking also raise the risk of VaD. Therefore, controlling these risk factors can help lower the chances of developing VaD. This update describes the subtypes of VaD, with details of their complex presentation, associated pathological lesions, and issues with diagnosis, prevention, and treatment. © The Author(s) 2016.

  2. Effect of magnesium on vascular reactivity in NOS inhibition-induced hypertension.

    Science.gov (United States)

    Basralı, Filiz; Nasırcılar Ülker, Seher; Koçer, Günnur; Ülker Karadamar, Pınar; Özyurt, Dilek; Cengiz, Melike; Şentürk, Ümit Kemal

    2015-06-01

    This study investigated the effect of magnesium on the vascular reactivity of conduit and resistance arteries in a nitric oxide synthase inhibition-induced hypertension model. The aorta and third-order branches of the mesenteric artery were dissected from normotensive control and hypertensive rats, and their constriction and dilation responses in physiological saline solution containing normal (1.2 mM) or high (4.8 mM) magnesium concentrations were examined. The responses of the vessels were evaluated using potassium chloride (KCl) and phenylephrine (Phe), acetylcholine (ACh) and sodium nitroprusside. The Phe-induced constriction response of the aortic rings increased, whereas the ACh-induced dilation response decreased, in the hypertensive group compared to controls, in the presence of a normal magnesium concentration. High magnesium did not alter these responses in either group. Both the KCl- and Phe-induced constriction responses of the mesenteric arteries increased, and the ACh-induced dilation response decreased in the hypertensive group compared to controls, in the presence of a normal magnesium concentration. High magnesium significantly decreased the KCl and Phe-induced constriction and increased the ACh-induced dilation response of the mesenteric arteries in the hypertensive group, while it did not alter these responses in controls. This study suggests that high magnesium improves vascular reactivity of resistance-, but not conduit-type arteries in the nitric oxide synthase inhibition-induced hypertension model.

  3. Vascular pattern in enchondroma and chondrosarcoma: clinical and immunohistologic study.

    Science.gov (United States)

    Cintra, Francisco F; Etchebehere, Mauricio; Gonçalves, Jose C B; Cassone, Alejandro E; Amstalden, Eliane M I

    2014-09-01

    Although cartilaginous tumors have low microvascular density, vessels are important for the provision of nutrition so that the tumor can grow and generate metastasis. The aim of this study was to assess the value of the vascular pattern classification as a prognostic tool in chondrosarcomas (CSs) and its relation with vascular endothelial growth factor (VEGF) expression. This was a retrospective study of 21 enchondromas and 57 conventional CSs. Clinical data and outcome were retrieved from medical files. CSs histologic grades (on a scale of 1 to 3) were determined according to the World Health Organization classification. The vascular pattern (on a scale of A to C) was assessed through CD34, according to Kalinski. CD105 and VEGF were also evaluated. Poor outcome was significantly associated with vascular pattern groups B and C. Higher vascular pattern were 6.5 times more frequent in moderate-grade and high-grade CSs than in grade 1 CS. On multivariate analysis, a clear correlation was found between VEGF overexpression and B/C vascular patterns. Only 18 (benign and malignant) tumors stained for CD105. The results point to the use of the vascular pattern classification as a prognostic tool in CSs and to differentiate low-grade from moderate-grade/high-grade CSs. Vascular pattern might be also used to complement histologic grade, VEGF immunostaining, and microvascular density, for indicating a patient's prognosis. Low-grade CSs develop under low neoangiogenesis, which conforms to the slow growth rate of these tumors.

  4. Physical rock properties in and around a conduit zone by well-logging in the Unzen Scientific Drilling Project, Japan

    Science.gov (United States)

    Ikeda, R.; Kajiwara, T.; Omura, K.; Hickman, S.

    2008-01-01

    The objective of the Unzen Scientific Drilling Project (USDP) is not only to reveal the structure and eruption history of the Unzen volcano but also to clarify the ascent and degassing mechanisms of the magma conduit. Conduit drilling (USDP-4) was conducted in 2004, which targeted the magma conduit for the 1990-95 eruption. The total drilled length of USDP-4 was 1995.75??m. Geophysical well logging, including resistivity, gamma-ray, spontaneous potential, sonic-wave velocity, density, neutron porosity, and Fullbore Formation MicroImager (FMI), was conducted at each drilling stage. Variations in the physical properties of the rocks were revealed by the well-log data, which correlated with not only large-scale formation boundaries but also small-scale changes in lithology. Such variations were evident in the lava dike, pyroclastic rocks, and breccias over depth intervals ranging from 1 to 40??m. These data support previous models for structure of the lava conduit, in that they indicate the existence of alternating layers of high-resistivity and high P-wave velocity rocks corresponding to the lava dikes, in proximity to narrower zones exhibiting high porosity, low resistivity, and low P-wave velocity. These narrow, low-porosity zones are presumably higher in permeability than the adjacent rocks and may form preferential conduits for degassing during magma ascent. ?? 2008 Elsevier B.V.

  5. Vascular endothelial growth factor from embryonic status to cardiovascular pathology

    OpenAIRE

    Mohsen Azimi-Nezhad

    2014-01-01

    Vascular endothelial growth factor (VEGF) is a multifunctional cytokine with distinct functions in angiogenesis, lymphangiogenesis, vascular permeability, and hematopoiesis. VEGF is a highly conserved, disulfide-bonded dimeric glycoprotein of 34 to 45 kDa produced by several cell types including fibroblasts, neutrophils, endothelial cells, and peripheral blood mononuclear cells, particularly T lymphocytes and macrophages. Six VEGF isoforms are generated as a result of alternative splicing fro...

  6. Rapid prototyping of a double-layer polyurethane-collagen conduit for peripheral nerve regeneration.

    Science.gov (United States)

    Cui, Tongkui; Yan, Yongnian; Zhang, Renji; Liu, Li; Xu, Wei; Wang, Xiaohong

    2009-03-01

    A new technique for preparing double-layer polyurethane (PU)-collagen nerve conduits for peripheral nerve repair via a double-nozzle, low-temperature, deposition manufacturing (DLDM) system has been developed. The DLDM system is based on a digital prototyping approach, and uses a combination of thermally induced phase separation and freeze-drying. With this system, two kinds of biomaterials with different properties can be combined to produce scaffold structures with good biocompatibility in the inner layer and with the desired mechanical strength protruded by the outer. The forming precision is high, the wall thickness can be controlled, and a tight connection between the two layers can be achieved. The effects of changing the processing parameters and the material temperature on the structure of the scaffolds have been investigated. Additionally, the effect of material concentration on the mechanical strength and hydrophilic properties of the scaffolds has also been studied. Ideal peripheral nerve repair conduits, comprising an outer microporous layer of PU and internal oriented filaments of collagen, have been manufactured through optimizing the processing parameters and the biomaterial concentrations.

  7. 3D Printed Trileaflet Valve Conduits Using Biological Hydrogels and Human Valve Interstitial Cells

    Science.gov (United States)

    Duan, Bin; Kapetanovic, Edi; Hockaday, Laura A.; Butcher, Jonathan T.

    2014-01-01

    Tissue engineering has great potential to provide a functional de novo living valve replacement capable of integration with host tissue and growth. Among various valve conduit fabrication techniques, 3D bioprinting enables deposition of cells and hydrogels into 3D constructs with anatomical geometry and heterogeneous mechanical properties. Successful translation of this approach is however constrained by the dearth of printable and biocompatible hydrogel materials. Furthermore, it is not known how human valve cells respond to these printed environments. In this study, we develop 3D printable formulations of hybrid hydrogels based on methacrylated hyaluronic acid (Me-HA) and methacrylated gelatin (Me-Gel), and utilize them to bioprint heart valve conduits containing encapsulated human aortic valvular interstitial cells (HAVIC). Increasing Me-Gel concentration resulted in lower stiffness and higher viscosity, facilitated cell spreading, and better maintained HAVIC fibroblastic phenotype. Bioprinting accuracy was dependent upon the relative concentrations of Me-Gel and Me-HA, but when optimized enabled the fabrication of a trileaflet valve shape accurate to the original design. HAVIC encapsulated within bioprinted heart valves maintained high viability, and remodeled the initial matrix by depositing collagen and glyosaminoglycans. These findings represent the first rational design of bioprinted trileaflet valve hydrogels that regulate encapsulated human VIC behavior. The use of anatomically accurate living valve scaffolds through bioprinting may accelerate our understanding of physiological valve cell interactions and our progress towards de novo living valve replacements. PMID:24334142

  8. Impact of asymmetric lamp positioning on the performance of a closed-conduit UV reactor

    Directory of Open Access Journals (Sweden)

    Tipu Sultan

    2017-06-01

    Full Text Available Computational fluid dynamics (CFD analyses for the performance improvement of a closed-conduit ultraviolet (UV reactor were performed by changing the lamp positions from symmetric to asymmetric. The asymmetric lamp positioning can be useful for UV reactor design and optimization. This goal was achieved by incorporating the two performance factors, namely reduction equivalent dose (RED and system dose performance. Four cases were carried out for asymmetric lamp positioning within the UV reactor chamber and each case consisted of four UV lamps that were simulated once symmetrically and four times asymmetrically. The results of the four asymmetric cases were compared with the symmetric one. Moreover, these results were evaluated by using CFD simulations of a closed-conduit UV reactor. The fluence rate model, UVCalc3D was employed to validate the simulations results. The simulation results provide detailed information about the dose distribution, pathogen track modeling and RED. The RED value was increased by approximately 15% by using UVCalc3D fluence rate model. Additionally, the asymmetric lamp positioning of the UV lamps had more than 50% of the pathogens received a better and a higher UV dose than in the symmetric case. Consequently, the system dose performance was improved by asymmetric lamp positioning. It was concluded that the performance parameters (higher RED and system dose performance were improved by using asymmetric lamp positioning.

  9. [How Treatable is Vascular Dementia?].

    Science.gov (United States)

    Mori, Etsuro

    2016-04-01

    Vascular dementia is an umbrella term, encompassing the pathological changes in the brain due to cerebrovascular disease that result in dementia. Vascular dementia is the second most common form of dementia, after Alzheimer's disease. In this paper, I outline the concept of vascular dementia, the key aspects of the disease that are yet to be clarified, and the current status of clinical trials. Assessing these factors, I discuss how treatable vascular dementia presently is. Use of the term'vascular dementia'is riddled with uncertainties regarding disease classification, and non-standardized diagnostic criteria. There are difficulties in determining the exact relationship between cerebrovascular pathology and cognitive impairment. The comorbid effects of Alzheimer's pathology in some individuals also present an obstacle to reliable clinical diagnosis, and hinder research into effective management approaches. Vascular dementia is preventable and treatable, as there are established primary and secondary prevention measures for the causative cerebrovascular diseases, such as vascular risk factor intervention, antiplatelet therapy, and anticoagulation, amongst others. However, unlike Alzheimer's disease, there are no established symptomatic treatments for vascular dementia. Clinical trials of cholinesterase inhibitors and memantine indicate that they produce small cognitive benefits in patients with vascular dementia, though the exact clinical significance of these is uncertain. Data are insufficient to support the widespread use of these drugs in vascular dementia. Rehabilitation and physical and cognitive exercise may be beneficial, but evidence of cognitive benefit and relief of neuropsychiatric symptoms due to exercise is lacking.

  10. Ebselen does not improve oxidative stress and vascular function in patients with diabetes: a randomized, crossover trial.

    Science.gov (United States)

    Beckman, Joshua A; Goldfine, Allison B; Leopold, Jane A; Creager, Mark A

    2016-12-01

    Oxidative stress is a key driver of vascular dysfunction in diabetes mellitus. Ebselen is a glutathione peroxidase mimetic. A single-site, randomized, double-masked, placebo-controlled, crossover trial was carried out in 26 patients with type 1 or type 2 diabetes to evaluate effects of high-dose ebselen (150 mg po twice daily) administration on oxidative stress and endothelium-dependent vasodilation. Treatment periods were in random order of 4 wk duration, with a 4-wk washout between treatments. Measures of oxidative stress included nitrotyrosine, plasma 8-isoprostanes, and the ratio of reduced to oxidized glutathione. Vascular ultrasound of the brachial artery and plethysmographic measurement of blood flow were used to assess flow-mediated and methacholine-induced endothelium-dependent vasodilation of conduit and resistance vessels, respectively. Ebselen administration did not affect parameters of oxidative stress or conduit artery or forearm arteriolar vascular function compared with placebo treatment. There was no difference in outcome by diabetes type. Ebselen, at the dose and duration evaluated, does not improve the oxidative stress profile, nor does it affect endothelium-dependent vasodilation in patients with diabetes mellitus. Copyright © 2016 the American Physiological Society.

  11. Radical cystectomy and pelvic lymphadenectomy with ileal conduit urinary diversion and abdominal wall reconstruction: an interesting case of multidisciplinary management

    Directory of Open Access Journals (Sweden)

    Sofos SS

    2015-01-01

    Full Text Available Stratos S Sofos,1 Ciaran Walsh,2 Nigel J Parr,2 Kevin Hancock11Whiston Hospital, Prescot, 2Arrowe Park Hospital, Wirral, Merseyside, UKAbstract: The ileal conduit for urinary diversion after radical cystectomy is a well-described procedure. Furthermore, parastomal hernias, prolapse, stenosis, and retraction of the stoma have been reported as some of the more common complications of this procedure. The subsequent repair of parastomal hernias with a biological mesh and the potential of the conduit to “tunnel” through it has also been described. In this case report, we present a combined repair of a large incisional hernia with a cystectomy and a pelvic lymphadenectomy for invasive bladder cancer, with the use of a biological mesh for posterior component abdominal wall primary repair as well as for support to the ileal conduit used for urinary diversion.Keywords: incisional hernia, posterior component separation, biological mesh 

  12. [Estrogens and vascular thrombosis].

    Science.gov (United States)

    Colmou, A

    1982-09-01

    The incidence of thromboses among young women has increased with widespread use of oral contraceptives (OCs) due to the significant thromboembolic risk of estrogen. Estrogens intervene at the vascular, platelet, and plasma levels as a function of hormonal variations in the menstrual cycle, increasing the aggregability of the platelets and thrombocytes, accelerating the formation of clots, and decreasing the amount of antithrombin III. Estrogens are used in medicine to treat breast and prostate cancers and in gynecology to treat dysmenorrhea, during the menopause, and in contraception. Smoking, cardiovascular disease and hypertension, hypercholesterolemia, and diabetes are contraindicators to estrogen use. Thrombosis refers to blockage of a blood vessel by a clot or thrombus. Before estrogens are prescribed, a history of phlebitis, obesity, hyperlipidemia, or significant varicosities should be ruled out. A history of venous thrombosis, hyperlipoproteinemia, breast nodules, serious liver condition, allergies to progesterone, and some ocular diseases of vascular origin definitively rule out treatment with estrogens. A family history of infarct, embolism, diabetes, cancer, or vascular accidents at a young age signals a need for greater patient surveillance. All patients receiving estrogens should be carefully observed for signs of hypertension, hypercholesterolemia, hypercoagulability, or diabetes. Nurses have a role to play in carefully eliciting the patient's history of smoking, personal and family medical problems, and previous and current laboratory results, as well as in informing the patients of the risks and possible side effects of OCs, especially for those who smoke. Nurses should educate patients receiving estrogens, especially those with histories of circulatory problems, to avoid standing in 1 position for prolonged periods, avoid heat which is a vasodilator, avoid obesity, excercise regularly, wear appropriate footgear, and follow other good health

  13. Use of nerve conduits for peripheral nerve injury repair: A Web of Science-based literature analysis.

    Science.gov (United States)

    Nan, Jinniang; Hu, Xuguang; Li, Hongxiu; Zhang, Xiaonong; Piao, Renjing

    2012-12-15

    To identify global research trends in the use of nerve conduits for peripheral nerve injury repair. Numerous basic and clinical studies on nerve conduits for peripheral nerve injury repair were performed between 2002-2011. We performed a bibliometric analysis of the institutions, authors, and hot topics in the field, from the Web of Science, using the key words peripheral nerve and conduit or tube. peer-reviewed published articles on nerve conduits for peripheral nerve injury repair, indexed in the Web of Science; original research articles, reviews, meeting abstracts, proceedings papers, book chapters, editorial material, and news items. articles requiring manual searching or telephone access; documents not published in the public domain; and several corrected papers. (a) Annual publication output; (b) publication type; (c) publication by research field; (d) publication by journal; (e) publication by funding agency; (f) publication by author; (g) publication by country and institution; (h) publications by institution in China; (i) most-cited papers. A total of 793 publications on the use of nerve conduits for peripheral nerve injury repair were retrieved from the Web of Science between 2002-2011. The number of publications gradually increased over the 10-year study period. Articles constituted the main type of publication. The most prolific journals were Biomaterials, Microsurgery, and Journal of Biomedical Materials Research Part A. The National Natural Science Foundation of China supported 27 papers, more than any other funding agency. Of the 793 publications, almost half came from American and Chinese authors and institutions. Nerve conduits have been studied extensively for peripheral nerve regeneration; however, many problems remain in this field, which are difficult for researchers to reach a consensus.

  14. An in vivo model of in situ implantation using pulmonary valved conduit in large animals under off-pump condition.

    Science.gov (United States)

    Wu, Hao; Xu, Zhi-wei; Liu, Xian-min; Gong, Da; Wan, Ju-yi; Xu, Xiu-fang; Zhou, Zi-fan; Li, Wen-bin

    2013-12-01

    The application of pulmonary valved conduit to reconstruct the continuity between right ventricles and pulmonary artery is one of the major surgeries. This study aimed to establish an in vivo model of in situ implantation using pulmonary valved conduit in large animals under off-pump condition to validate the long-term effects of artificial pulmonary valved conduit. Domesticate juvenile male sheep and tissue-engineered porcine pulmonary valved conduit were used for the experiment: 30 sheep, weighing (15 ± 3) kg (range 13 to 17 kg) were randomly divided into two groups which were all operated under general anesthesia by off-pump surgery (group 1) and left thoracotomy (group 2). Two different off-pump surgical methods were used to perform cannulation in sheep pulmonary artery to replace part of sheep pulmonary artery with pulmonary valved conduit which will work together with sheep pulmonary artery and valves. During the experiments, animal survival, complication rates, operating time and blood loss were recorded to compare the results between groups and to establish a surgical method with minimal invasion, simplicity, safety, and high success rates. In group 1, a total of 15 cases of surgeries were performed, in which two sheep died; the operative mortality was 13.3% (2/15). In group 2, a total of 15 cases of surgeries were performed, and the surgical mortality rate was 0 (0/15). The operation time and blood loss in group 2 was significantly better than that in group 1. The postoperative echocardiograms showed that, after the surgeries by these two methods, the blood flows were normal, and the valves can open and close freely. Autopsy after 6 months showed that the inner wall and the valves of pulmonary valved conduit were smooth with no thrombus formation. These two off-pump methods are feasible and safe with fewer traumas; but the second method is better and particularly suitable for the establishment of a juvenile animal model.

  15. Aneurysmal degeneration of the donor artery after vascular access.

    Science.gov (United States)

    Marzelle, Jean; Gashi, Valbon; Nguyen, Hong-Duyen; Mouton, Albert; Becquemin, Jean-Pierre; Bourquelot, Pierre

    2012-04-01

    reconstructive conduit is not straightforward. Copyright © 2012 Society for Vascular Surgery. Published by Mosby, Inc. All rights reserved.

  16. The pathobiology of vascular dementia.

    Science.gov (United States)

    Iadecola, Costantino

    2013-11-20

    Vascular cognitive impairment defines alterations in cognition, ranging from subtle deficits to full-blown dementia, attributable to cerebrovascular causes. Often coexisting with Alzheimer's disease, mixed vascular and neurodegenerative dementia has emerged as the leading cause of age-related cognitive impairment. Central to the disease mechanism is the crucial role that cerebral blood vessels play in brain health, not only for the delivery of oxygen and nutrients, but also for the trophic signaling that inextricably links the well-being of neurons and glia to that of cerebrovascular cells. This review will examine how vascular damage disrupts these vital homeostatic interactions, focusing on the hemispheric white matter, a region at heightened risk for vascular damage, and on the interplay between vascular factors and Alzheimer's disease. Finally, preventative and therapeutic prospects will be examined, highlighting the importance of midlife vascular risk factor control in the prevention of late-life dementia. Copyright © 2013 Elsevier Inc. All rights reserved.

  17. Trimethylene carbonate-caprolactone conduit with poly-p-dioxanone microfilaments to promote regeneration after spinal cord injury.

    Science.gov (United States)

    Novikova, Liudmila N; Kolar, Mallappa K; Kingham, Paul J; Ullrich, Andreas; Oberhoffner, Sven; Renardy, Monika; Doser, Michael; Müller, Erhard; Wiberg, Mikael; Novikov, Lev N

    2017-11-22

    Spinal cord injury (SCI) is often associated with scarring and cavity formation and therefore bridging strategies are essential to provide a physical substrate for axonal regeneration. In this study we investigated the effects of a biodegradable conduit made from trimethylene carbonate and ε-caprolactone (TC) containing poly-p-dioxanone microfilaments (PDO) with longitudinal grooves on regeneration after SCI in adult rats. In vitro studies demonstrated that different cell types including astrocytes, meningeal fibroblasts, Schwann cells and adult sensory dorsal root ganglia neurons can grow on the TC and PDO material. For in vivo experiments, the TC/PDO conduit was implanted into a small 2-3 mm long cavity in the C3-C4 cervical segments immediately after injury (acute SCI) or at 2-5 months after initial surgery (chronic SCI). At 8 weeks after implantation into acute SCI, numerous 5HT-positive descending raphaespinal axons and sensory CGRP-positive axons regenerated across the conduit and were often associated with PDO microfilaments and migrated host cells. Implantation into chronically injured SCI induced regeneration mainly of the sensory CGRP-positive axons. Although the conduit had no effect on the density of OX42-positive microglial cells when compared with SCI control, the activity of GFAP-positive astrocytes was reduced. The results suggest that a TC/PDO conduit can support axonal regeneration after acute and chronic SCI even without addition of exogenous glial or stem cells. Biosynthetic conduits can support regeneration after spinal cord injury but often require addition of cell therapy and neurotrophic factors. This study demonstrates that biodegradable conduits made from trimethylene carbonate and ε-caprolactone with poly-p-dioxanone microfilaments alone can promote migration of different host cells and stimulate axonal regeneration after implantation into acute and chronic spinal cord injury. These results can be used to develop biosynthetic

  18. Perception et anticipation du comportement d’autrui en situation simulée de conduite automobile

    OpenAIRE

    Munduteguy, Christophe; Darses, Françoise

    2007-01-01

    L’anticipation du comportement d’autrui est un mécanisme central dans la gestion des interactions. L’activité de conduite automobile a la particularité de maintenir les interactants à distance les uns des autres, les obligeant à gérer leur interdépendance à l’aide de ressources limitées pour communiquer. Sur la base d’entretiens recueillis en simulation de conduite, on montre que le pronostic du comportement d’autrui se construit sur des indices issus de re...

  19. Applicability of handmade expanded polytetrafluoroethylene trileaflet-valved conduits for pulmonary valve reconstruction: An ex vivo and in vivo study.

    Science.gov (United States)

    Kan, Chung-Dann; Wang, Jieh-Neng; Chen, Wei-Ling; Lu, Pong-Jeu; Chan, Ming-Yao; Lin, Chia-Hung; Hsieh, Wan-Chin

    2017-09-20

    The handmade expanded polytetrafluoroethylene (ePTFE) trileaflet-valved conduit could potentially be used as a substitute pulmonary valve replacement material, especially in children. The current study investigated (1) the function of the ePTFE trileaflet-valved conduits in an ex vivo experimental system and (2) the short-term performance of the conduit in a porcine model to verify its clinical applicability. The competency of the ePTFE trileaflet-valved conduits was estimated through ex vivo (using a pulmonary mock circulation loop) and in vivo (in a porcine model with a damaged pulmonary valve) experiments. Explants were examined by gross morphology and histopathologic examination. In the ex vivo experiment, the ePTFE trileaflet-valved conduits were determined to effectively increase mean pulmonary pressure from 10.2 to 14.4 mm Hg compared with defective silicon-valved conduits. In addition, the regurgitation fraction value of ePTFE trileaflet-valved conduits was 15.9% to 18.1%, which was significantly better than the defective valve conduits (regurgitation fraction = 73.5%-85.7%). In the in vivo experiment, the valved conduits were confirmed to be with good valve position maintenance, and the valve and leaflets showed no signs of thickening or peeling after a short-term implantation period. There were also no significant signs of inflammation reaction on histopathologic examination. The ePTFE trileaflet-valved conduits for pulmonary valve reconstruction showed acceptable performance and outcomes in the ex vivo and in vivo experiments. The ePTFE trileaflet-valved conduit may be clinically useful, although additional studies in animals should be conducted to determine its long-term outcomes. Copyright © 2017 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.

  20. Anaesthesia for vascular emergencies.

    Science.gov (United States)

    Ellard, L; Djaiani, G

    2013-01-01

    Patients presenting with vascular emergencies including acute aortic syndrome, ruptured thoracic or abdominal aortic aneurysms, thoracic aortic trauma and acute lower limb ischaemia have a high risk of peri-operative morbidity and mortality. Although anatomical suitability is not universal, endovascular surgery may improve mortality and the results of ongoing randomised controlled trials are awaited. Permissive hypotension pre-operatively should be the standard of care with the systolic blood pressure kept to 50-100 mmHg as long as consciousness is maintained. The benefit of local anaesthesia over general anaesthesia is not definitive and this decision should be tailored for a given patient and circumstance. Cerebrospinal fluid drainage for prevention of paraplegia is often impractical in the emergency setting and is not backed by strong evidence; however, it should be considered postoperatively if symptoms develop. We discuss the pertinent anaesthetic issues when a patient presents with a vascular emergency and the impact that endovascular repair has on anaesthetic management. Anaesthesia © 2012 The Association of Anaesthetists of Great Britain and Ireland.

  1. Pediatric vascularized composite allotransplantation.

    Science.gov (United States)

    Doumit, Gaby; Gharb, Bahar Bassiri; Rampazzo, Antonio; Papay, Francis; Siemionow, Maria Z; Zins, James E

    2014-10-01

    Vascularized composite allotransplantation (VCA) has experienced a growing acceptance, which has led to a debate centered on extending the indications of the procedure to include pediatric patients. The aim of this article was to discuss such indications based on the evidence in pediatric solid organ transplantation, reconstructive surgery in children, and VCA in adult patients. Papers published on the outcomes of pediatric solid organ transplantation, growth after replantation of extremities, vascularized autologous tissue transfer, craniofacial surgery, orthognathic procedures, facial fractures, and outcomes after repair of peripheral nerves in children were reviewed. Although the outcomes of solid organ transplantation in children have improved, the transplanted organs continue to have a limited lifespan. Long-term immunosuppressive therapy exposes the patients to an increased lifetime risk of infections, diabetes, hypertension, dyslipidemia, cardiovascular disease, and malignancy. Growth impairment and learning disabilities are other relevant drawbacks, which affect the pediatric recipients. Nonadherence to medication is a common cause of graft dysfunction and loss among the adolescent transplant recipients. Rejection episodes, hospitalizations, and medication adverse effects contribute negatively to the quality of life of the patients. Although normal growth after limb transplantation could be expected, pediatric facial transplant recipients may present with arrest of growth of transplanted midfacial skeleton. Considering the non-life-threatening nature of the conditions that lead to eligibility for VCA, it is suggested that it is premature to extend the indications of VCA to include pediatric patients under the currently available immunosuppressive protocols.

  2. Spinal Cord Vascular Disease

    Directory of Open Access Journals (Sweden)

    Abdoreza Ghoreishi

    2017-02-01

    Full Text Available The spinal cord is subject to many of the same vascular diseases that involve the brain, but its anatomy and embryology render it susceptible to some syndromes that do not have intracranial counterparts.The embryonic arterial supply to the spinal cord derives from intradural vessels that enter at each spinal level and divide to follow the dorsal and ventral roots. SPINAL CORD ISCHEMIA: The midthoracic levels of the spinal cord are traditionally considered to be the most vulnerable to compromise from hypoperfusion, but more recent evidence suggests that the lower thoracic cord is at greater risk . The actual prevalence of spinal cord infarction is unknown, but is generally cited as representing 1% to 2% of all central neurovascular events and 5% to 8% of all acute myelopathies. Weakness (100%, sensory loss (89%, back pain at onset (82%, and urinary complaints requiring catheterization (75% were the most common symptoms of cord ischemia at the time of presentation . Weakness most commonly affects both legs. Examination typically reveals flaccid paresis accompanied by diminished superficial and tendon reflexes below the level of the lesion. Preservation of strength and reflexes suggests the rare syndrome of posterior spinal artery territory infarction. Weakness most commonly affects both legs. Examination typically reveals flaccid paresis accompanied by diminished superficial and tendon reflexes below the level of the lesion. Preservation of strength and reflexes suggests the rare syndrome of posterior spinal artery territory infarction.   Aortic pathologies with regional hemodynamic compromise are the most common cause of spinal cord infarction, accounting for 30% to 40% of cases.                                                                                 The medical management of spinal cord ischemia is generally supportive and focused on reducing risk for

  3. Comment faire parler les images aux rayons X du conduit vocal

    Directory of Open Access Journals (Sweden)

    Laprie Yves

    2014-07-01

    Full Text Available Cet article présente la méthodologie de construction, de dépouillement et d’exploitation d’une base de données cinéradiographiques. L’élaboration du contenu du corpus est un aspect essentiel puisqu’il doit prendre en compte les contraintes inhérentes à la technologie d’acquisition et l’objectif phonétique. Dans le cas de la cinéradiographie on privilégie des phrases courtes formées de mots et non de logatomes. Une base de données cinéradiographique est formée d’un très grand nombre d’images. Le dépouillement consiste à tracer le contour des articulateurs de la parole et ce travail doit être automatisé afin de pouvoir traiter un volume de données suffisant pour assurer une exploitation ultérieure pertinente. Des algorithmes de suivi semi-automatique ou automatique, ainsi qu’une interface très conviviale ont donc été développés pour atteindre cet objectif. Dans ce travail l’exploitation des corpus a consisté à développer et valider des modèles articulatoires en étudiant deux aspects : (1 l’utilisation d’un modèle construit sur un locuteur pour approcher la forme du conduit vocal d’un autre locuteur, (2 l’approximation précise du conduit vocal au voisinage de la constriction parce qu’elle a un impact important sur l’acoustique de la parole. Ces modèles, et plus généralement une représentation géométrique du conduit vocal, peuvent être utilisés en synthèse articulatoire afin d’étudier le lien entre les domaines articulatoire et acoustique. Nous montrons en particulier qu’il est possible de resynthétiser de la parole de bonne qualité à partir des contours extraits des films.

  4. Temporary vascular shunting in vascular trauma: A 10-year review ...

    African Journals Online (AJOL)

    Five patients with non-viable limbs had the vessel ligated. Conclusions. A TIVS in the damage control setting is both life- and limb-saving. These shunts can be inserted safely in a facility without access to a surgeon with vascular surgery experience if there is uncontrollable bleeding or the delay to definitive vascular surgery ...

  5. Temporary vascular shunting in vascular trauma: A 10-year review ...

    African Journals Online (AJOL)

    part of a damage control procedure, 7 patients were referred from a hospital without access to vascular surgical facilities with the TIVS in situ, and in the remaining 6 patients the TIVS was inserted during repair of a lower limb fracture with an associated vascular injury. Damage control procedure. Twenty-two patients had a ...

  6. Additive Manufacturing of Vascular Grafts and Vascularized Tissue Constructs.

    Science.gov (United States)

    Elomaa, Laura; Yang, Yunzhi Peter

    2017-10-01

    There is a great need for engineered vascular grafts among patients with cardiovascular diseases who are in need of bypass therapy and lack autologous healthy blood vessels. In addition, because of the severe worldwide shortage of organ donors, there is an increasing need for engineered vascularized tissue constructs as an alternative to organ transplants. Additive manufacturing (AM) offers great advantages and flexibility of fabrication of cell-laden, multimaterial, and anatomically shaped vascular grafts and vascularized tissue constructs. Various inkjet-, extrusion-, and photocrosslinking-based AM techniques have been applied to the fabrication of both self-standing vascular grafts and porous, vascularized tissue constructs. This review discusses the state-of-the-art research on the use of AM for vascular applications and the key criteria for biomaterials in the AM of both acellular and cellular constructs. We envision that new smart printing materials that can adapt to their environment and encourage rapid endothelialization and remodeling will be the key factor in the future for the successful AM of personalized and dynamic vascular tissue applications.

  7. Microstructured human fibroblast-derived extracellular matrix scaffold for vascular media fabrication.

    Science.gov (United States)

    Bourget, Jean-Michel; Laterreur, Véronique; Gauvin, Robert; Guillemette, Maxime D; Miville-Godin, Caroline; Mounier, Maxence; Tondreau, Maxime Y; Tremblay, Catherine; Labbé, Raymond; Ruel, Jean; Auger, François A; Veres, Teodor; Germain, Lucie

    2017-09-01

    In the clinical and pharmacological fields, there is a need for the production of tissue-engineered small-diameter blood vessels. We have demonstrated previously that the extracellular matrix (ECM) produced by fibroblasts can be used as a scaffold to support three-dimensional (3D) growth of another cell type. Thus, a resistant tissue-engineered vascular media can be produced when such scaffolds are used to culture smooth muscle cells (SMCs). The present study was designed to develop an anisotropic fibroblastic ECM sheet that could replicate the physiological architecture of blood vessels after being assembled into a small diameter vascular conduit. Anisotropic ECM scaffolds were produced using human dermal fibroblasts, grown on a microfabricated substrate with a specific topography, which led to cell alignment and unidirectional ECM assembly. Following their devitalization, the scaffolds were seeded with SMCs. These cells elongated and migrated in a single direction, following a specific angle relative to the direction of the aligned fibroblastic ECM. Their resultant ECM stained for collagen I and III and elastin, and the cells expressed SMC differentiation markers. Seven days after SMCs seeding, the sheets were rolled around a mandrel to form a tissue-engineered vascular media. The resulting anisotropic ECM and cell alignment induced an increase in the mechanical strength and vascular reactivity in the circumferential direction as compared to unaligned constructs. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  8. Laparoscopic vascular anastomoses: does robotic (Zeus-Aesop) assistance help to overcome the learning curve?

    Science.gov (United States)

    Nio, D; Bemelman, W A; Balm, R; Legemate, D A

    2005-08-01

    Considerable training is necessary to master laparoscopic suturing and knot-tying. Robotic systems are assumed to facilitate these skills and shorten the learning curve. The effect of laparoscopic experience and robotic assistance on the learning curve of vascular anastomoses was studied. A laparoscopically experienced surgeon and a laparoscopically inexperienced surgeon made alternating laparoscopic vascular anastomoses and robot-assisted laparoscopic vascular anastomoses using a Zeus-Aesop surgical robotic system with various prosthetic conduits and suture materials in a laparoscopic training box. Neither laparoscopic method influenced the quality score or leakage rate, but with laparoscopic experience, significantly fewer failures were made. Suturing and knot-tying were faster with laparoscopic experience both with and without the robotic system, and fewer stitch actions and knot actions were performed. The learning curves of both surgeons were not improved by the robotic system. Experience is the most important factor in the performance of laparoscopic vascular anastomoses. The robotic system was not helpful in shortening the learning curve.

  9. Long-term follow-up after implantation of the Shelhigh (R) No-React (R) complete biological aortic valved conduit

    NARCIS (Netherlands)

    Reineke, David C.; Kaya, Abdullah; Heinisch, Paul P.; Oezdemir, Berna; Winkler, Bernhard; Huber, Christoph; Heijmen, Robin H.; Morshuis, Wim; Carrel, Thierry P.; Englberger, Lars

    2016-01-01

    OBJECTIVES: Long-term follow-up reports after implantation of the Shelhigh (R) (Shelhigh, Inc., NJ, USA) No-React (R) aortic valved conduit used for aortic root replacement do not exist. METHODS: Between November 1998 and December 2007, the Shelhigh (R) No-React (R) aortic valved conduit was

  10. The results of denatured homologous vein grafts as conduits for secondary haemodialysis access surgery.

    Science.gov (United States)

    Heintjes, R J; Eikelboom, B C; Steijling, J J; van Reedt Dortland, R W; van der Heijden, F H; Bastini, M; van der Graaf, Y; Blankestijn, P J; Vos, J

    1995-01-01

    To determine the value of denatured homologous vein grafts as a conduit for secondary haemodialysis access. Retrospective clinical study. 2 University Hospitals. One-hundred-and-twenty-five patients received 195 grafts over a period of five years. Fifty-six first grafts (45%) functioned without complications throughout the study period of 5.8 years. Primary patency was 57% after 1 year and 25% after 3 years of follow-up. Of the initial grafts, 69 (55%) needed 161 interventions, for thrombosis (n = 59), stenosis (n = 43), failure beyond repair (n = 40), aneurysm (n = 12), infection (n = 4), steal syndrome (n = 1), and other causes (n = 2). Secondary patency was 76% at 1 year and 52% at 3 years of follow-up. A major advantage of these grafts was the low rate (2.6%) of infection. Aneurysm formation occurred 17 times in 195 grafts (8.7%). Denatured homologous vein graft is a good alternative in secondary access surgery.

  11. Nutrition and vascular dementia.

    Science.gov (United States)

    Perez, L; Heim, L; Sherzai, A; Jaceldo-Siegl, K; Sherzai, A

    2012-04-01

    The objective of this review was to elucidate the relationship between VaD and various nutritional factors based on epidemiological studies. Vascular dementia (VaD) is the second most common type of dementia. The prevalence of VaD continues to increase as the US population continues to grow and age. Currently, control of potential risk factors is believed to be the most effective means of preventing VaD. Thus, identification of modifiable risk factors for VaD is crucial for development of effective treatment modalities. Nutrition is one of the main modifiable variables that may influence the development of VaD. A systematic review of literature was conducted using the PubMed, Web of Science, and CINAHL Plus databases with search parameters inclusive of vascular dementia, nutrition, and vascular cognitive impairment (VCI). Fourteen articles were found that proposed a potential role of specific nutritional components in VaD. These components included antioxidants, lipids, homocysteine, folate, vitamin B12, and fish consumption. Antioxidants, specifically Vitamin E and C, and fatty fish intake were found to be protective against VaD risk. Fried fish, elevated homocysteine, and lower levels of folate and vitamin B12 were associated with increased VaD. Evidence for dietary lipids was inconsistent, although elevated midlife serum cholesterol may increase risk, while late-life elevated serum cholesterol may be associated with decreased risk of VaD. Currently, the most convincing evidence as to the relationship between VaD and nutrition exists for micronutrients, particularly Vitamin E and C. Exploration of nutrition at the macronutrient level and additional long term prospective cohort studies are warranted to better understand the role of nutrition in VaD disease development and progression. At present, challenges in this research include limitations in sample size, which was commonly cited. Also, a variety of diagnostic criteria for VaD were employed in the studies

  12. The Danish Vascular Registry, Karbase

    Directory of Open Access Journals (Sweden)

    Eldrup N

    2016-10-01

    Full Text Available Nikolaj Eldrup,1,2 Charlotte Cerqueira,3 Louise de la Motte,2,4 Lisbet Knudsen Rathenborg,2,4 Allan K Hansen2,5 1Department of Cardiothoracic and Vascular Surgery, Aarhus University Hospital, 2Karbase, The Danish Vascular Registry, Aarhus, 3Registry Support Centre (East – Epidemiology and Biostatistics, Research Centre for Prevention and Health, Capital Region of Denmark, 4Department of Vascular Surgery, Rigshospitalet, Copenhagen University Hospital, Copenhagen, 5Department of Vascular Surgery, Aalborg University Hospital, Aalborg, Denmark Aim: The Danish Vascular Registry (DVR, Karbase, is monitoring arterial and advanced vein interventions conducted at all vascular departments in Denmark. The main aim of the DVR is to improve the quality of treatment for patients undergoing vascular surgery in Denmark by using the registry for quality assessment and research. Study population: All patients undergoing vascular interventions (surgical and endovascular at any vascular department in Denmark are registered in the DVR. The DVR was initiated in 1989, and each year, ~9,000 procedures are added. By January 2016, .180,000 procedures have been recorded. Since 2001, data completeness has been .90% (compared to the Danish National Patient Register. Main variables: Variables include information on descriptive patient data (ie, age, sex, height, and weight and comorbidity (ie, previous cardiovascular disease and diabetes. Process variable includes waiting time (time from event to medical contact and treatment and the type of procedures conducted. Outcome variables for in-hospital complications (ie, wound complications, myocardial infarction, stroke, amputation, respiratory complications, and renal insufficiency and 30-day patency are submitted. Variables for medical treatment (antithrombotic and statin treatment, amputation, and survival are extracted from nationwide, administrative registers. Conclusion: The DVR reports outcome on key indicators for

  13. Cysteamine prevents vascular leakage through inhibiting transglutaminase in diabetic retina.

    Science.gov (United States)

    Lee, Yeon-Ju; Jung, Se-Hui; Hwang, JongYun; Jeon, Sohee; Han, Eun-Taek; Park, Won Sun; Hong, Seok-Ho; Kim, Young-Myeong; Ha, Kwon-Soo

    2017-10-01

    Cysteamine (an aminothiol), which is derived from coenzyme A degradation and metabolized into taurine, has beneficial effects against cystinosis and neurodegenerative diseases; however, its role in diabetic complications is unknown. Thus, we sought to determine the preventive effect of cysteamine against hyperglycemia-induced vascular leakage in the retinas of diabetic mice. Cysteamine and ethanolamine, the sulfhydryl group-free cysteamine analogue, inhibited vascular endothelial growth factor (VEGF)-induced stress fiber formation and vascular endothelial (VE)-cadherin disruption in endothelial cells, which play a critical role in modulating endothelial permeability. Intravitreal injection of the amine compounds prevented hyperglycemia-induced vascular leakage in the retinas of streptozotocin-induced diabetic mice. We then investigated the potential roles of reactive oxygen species (ROS) and transglutaminase (TGase) in the cysteamine prevention of VEGF-induced vascular leakage. Cysteamine, but not ethanolamine, inhibited VEGF-induced ROS generation in endothelial cells and diabetic retinas. In contrast, VEGF-induced TGase activation was prevented by both cysteamine and ethanolamine. Our findings suggest that cysteamine protects against vascular leakage through inhibiting VEGF-induced TGase activation rather than ROS generation in diabetic retinas. © 2017 Society for Endocrinology.

  14. BUILDOUT AND UPGRADE OF CENTRAL EMERGENCY GENERATOR SYSTEM, GENERATOR 3 AND 4 ELECTRICAL INSTALLATION

    Energy Technology Data Exchange (ETDEWEB)

    Gary D. Seifert; G. Shawn West; Kurt S. Myers; Jim Moncur

    2006-07-01

    SECTION 01000—SUMMARY OF WORK PART 1—GENERAL 1.1 SUMMARY The work to be performed under this project consists of providing the labor, equipment, and materials to perform "Buildout and Upgrade of Central Emergency Generator System, Generator 3 and 4 Electrical Installation" for the National Aeronautics and Space Administration at the Dryden Flight Research Center (NASA/DFRC), Edwards, California 93523. All modifications to existing substations and electrical distribution systems are the responsibility of the contractor. It is the contractor’s responsibility to supply a complete and functionally operational system. The work shall be performed in accordance with these specifications and the related drawings. The work of this project is defined by the plans and specifications contained and referenced herein. This work specifically includes but is not limited to the following: Scope of Work - Installation 1. Install all electrical wiring and controls for new generators 3 and 4 to match existing electrical installation for generators 1 and 2 and in accordance with drawings. Contractor shall provide as-built details for electrical installation. 2. Install battery charger systems for new generators 3 and 4 to match existing battery charging equipment and installation for generators 1 and 2. This may require exchange of some battery charger parts already on-hand. Supply power to new battery chargers from panel and breakers as shown on drawings. Utilize existing conduits already routed to generators 3 and 4 to field route the new wiring in the most reasonable way possible. 3. Install electrical wiring for fuel/lube systems for new generators 3 and 4 to match existing installation for generators 1 and 2. Supply power to lube oil heaters and fuel system (day tanks) from panel and breakers as shown on drawings. Utilize existing conduits already routed to generators 3 and 4 to field route the new wiring in the most reasonable way possible. Add any conduits necessary to

  15. A polylactic acid non-woven nerve conduit for facial nerve regeneration in rats.

    Science.gov (United States)

    Matsumine, Hajime; Sasaki, Ryo; Yamato, Masayuki; Okano, Teruo; Sakurai, Hiroyuki

    2014-06-01

    This study developed a biodegradable nerve conduit with PLA non-woven fabric and evaluated its nerve regeneration-promoting effect. The buccal branch of the facial nerve of 8 week-old Lewis rats was exposed, and a 7 mm nerve defect was created. A nerve conduit made of either PLA non-woven fabric (mean fibre diameter 460 nm), or silicone tube filled with type I collagen gel, or an autologous nerve, was implanted into the nerve defect, and their nerve regenerative abilities were evaluated 13 weeks after the surgery. The number of myelinated neural fibres in the middle portion of the regenerated nerve was the highest for PLA tubes (mean ± SD, 5051 ± 2335), followed by autologous nerves (4233 ± 590) and silicone tubes (1604 ± 148). Axon diameter was significantly greater in the PLA tube group (5.17 ± 1.69 µm) than in the silicone tube group (4.25 ± 1.60 µm) and no significant difference was found between the PLA tube and autograft (5.53 ± 1.93 µm) groups. Myelin thickness was greatest for the autograft group (0.65 ± 0.24 µm), followed by the PLA tube (0.54 ± 0.18 µm) and silicone tube (0.38 ± 0.12 µm) groups, showing significant differences among the three groups. The PLA non-woven fabric tube, composed of randomly-connected PLA fibres, is porous and has a number of advantages, such as sufficient strength to maintain luminal structure. The tube has demonstrated a comparable ability to induce peripheral nerve regeneration following autologous nerve transplantation. Copyright © 2012 John Wiley & Sons, Ltd.

  16. Pockets, conduits, channels, and plumes: links to volcanism and orogeny in the rollback dominated western Mediterranean

    Science.gov (United States)

    Miller, Meghan S.; Sun, Daoyuan; O'Driscoll, Leland; Becker, Thorsten W.; Holt, Adam; Diaz, Jordi; Thomas, Christine

    2015-04-01

    Detailed mantle and lithospheric structure from the Canary Islands to Iberia have been imaged with data from recent temporary deployments and select permanent stations from over 300 broadband seismometers. The stations extended across Morocco and Spain as part of the PICASSO, IberArray, and Morocco-Münster experiments. We present results from S receiver functions (SRF), shear wave splitting, waveform modeling, and geodynamic models that help constrain the tectonic evolution of the westernmost Mediterranean, including orogenesis of the Atlas Mountains and occurrence of localized alkaline volcanism. Our receiver function images, in agreement with previous geophysical modeling, show that the lithosphere is thin (~65 km) beneath the Atlas, but thickens (~100 km) over a very short length scale at the flanks of the mountains. We find that these dramatic changes in lithospheric thickness also correspond to dramatic decreases in delay times inferred from S and SKS splitting observations of seismic anisotropy. Pockets and conduits of low seismic velocity material below the lithosphere extend along much of the Atlas to Southern Spain and correlate with the locations of Pliocene-Quaternary magmatism. Waveform analysis from the USC linear seismic array across the Atlas Mountains constrains the position, shape, and physical characteristics of one localized, low velocity conduit that extends from the uppermost mantle (~200 km depth) up to the volcanoes in the Middle Atlas. The shape, position and temperature of these seismically imaged low velocity anomalies, topography of the base of the lithosphere, morphology of the subducted slab beneath the Alboran Sea, position of the West African Craton and correlation with mantle flow inferred from shear wave splitting suggest that the unusually high topography of the Atlas Mountains and isolated recent volcanics are due to active mantle support that may be from material channeled from the Canary Island plume.

  17. Conduit dynamics for Vulcanian explosions at Soufriere Hills Volcano, Montserrat, from strainmeter data

    Science.gov (United States)

    Chardot, L.; Voight, B.; Stewart, R.; Linde, A. T.; Sacks, S. I.; Hidayat, D.; Fournier, N.

    2009-12-01

    The Soufrière Hills Volcano (SHV), Montserrat, has been erupting for over 14 years, with three semi-continuous periods of extrusion (~1-2 yr) separated by three long pauses. The third pause ended in late July 2008 but subsequent activity was discontinuous and comprised two short periods of extrusion with explosive activity. Vulcanian explosions at SHV in July and December 2008 and on 3 January 2009 were recorded on the CALIPSO array with Sacks-Evertson dilatometers. (The CALIPSO array contains specialized instruments in four strategically located ~200m-deep-boreholes installed to investigate the dynamics of the SHV magmatic system). The explosions resulted in clear, coherent strain-steps (amplitude range ca. ~2-140 nanostrain). We report here on observations of strainmeter and microbarometer data, which allow us to describe the evolution of conduit dynamics in the explosions. The strain data are corrected for air pressure effects, and compared to seismic observations, plume heights to >12 km, and mass erupted, in order to constrain conduit pressure, and the dynamics of the events. The explosions share many similarities and strain data for these explosions are (mainly) characterized by contractive dilatation offset at all sites, from 5.4 to 9.6 km from the crater. Barometer data show the influence of atmospheric pressure changes on the dilatometer strains and yield further information on eruption dynamics. The strain steps are correlated with explosion plume height and mass erupted and may be useful for rapid assessment of aviation hazards from airborne ash. The CALIPSO instrument network is supported by NSF.

  18. Protein Kinase C as Regulator of Vascular Smooth Muscle Function and Potential Target in Vascular Disorders.

    Science.gov (United States)

    Ringvold, H C; Khalil, R A

    2017-01-01

    Vascular smooth muscle (VSM) plays an important role in maintaining vascular tone. In addition to Ca2+-dependent myosin light chain (MLC) phosphorylation, protein kinase C (PKC) is a major regulator of VSM function. PKC is a family of conventional Ca2+-dependent α, β, and γ, novel Ca2+-independent δ, ɛ, θ, and η, and atypical ξ, and ι/λ isoforms. Inactive PKC is mainly cytosolic, and upon activation it undergoes phosphorylation, maturation, and translocation to the surface membrane, the nucleus, endoplasmic reticulum, and other cell organelles; a process facilitated by scaffold proteins such as RACKs. Activated PKC phosphorylates different substrates including ion channels, pumps, and nuclear proteins. PKC also phosphorylates CPI-17 leading to inhibition of MLC phosphatase, increased MLC phosphorylation, and enhanced VSM contraction. PKC could also initiate a cascade of protein kinases leading to phosphorylation of the actin-binding proteins calponin and caldesmon, increased actin-myosin interaction, and VSM contraction. Increased PKC activity has been associated with vascular disorders including ischemia-reperfusion injury, coronary artery disease, hypertension, and diabetic vasculopathy. PKC inhibitors could test the role of PKC in different systems and could reduce PKC hyperactivity in vascular disorders. First-generation PKC inhibitors such as staurosporine and chelerythrine are not very specific. Isoform-specific PKC inhibitors such as ruboxistaurin have been tested in clinical trials. Target delivery of PKC pseudosubstrate inhibitory peptides and PKC siRNA may be useful in localized vascular disease. Further studies of PKC and its role in VSM should help design isoform-specific PKC modulators that are experimentally potent and clinically safe to target PKC in vascular disease. © 2017 Elsevier Inc. All rights reserved.

  19. Early and late failure of tissue-engineered pulmonary valve conduits used for right ventricular outflow tract reconstruction in patients with congenital heart disease.

    Science.gov (United States)

    Perri, Gianluigi; Polito, Angelo; Esposito, Claudia; Albanese, Sonia B; Francalanci, Paola; Pongiglione, Giacomo; Carotti, Adriano

    2012-06-01

    To identify factors associated with the surgical outcome in patients undergoing right ventricular outflow tract reconstruction (RVOTR) using decellularized tissue-engineered pulmonary valve conduits (TEPVc) and to study their safety and longevity. From April 2006 to April 2010, 93 patients underwent either palliative or corrective RVOTR using Matrix P (37) and Matrix P Plus (56) xenogenic decellularized TEPVc (size range 11-27 mm). Median age and weight at operation were 20 (0.16-290) months and 10.15 (2.65-86) kg respectively. Primary and redo surgery occurred in 40 and 60% of cases, respectively. Eighty-eight patients (94.6%) received conduit implantation in the framework of corrective surgery, whereas in 5 (5.4%) a palliative procedure was undertaken. Follow-up was complete in 91% of patients, with a median duration of 12 months (range: 2 days-51 months). Data analysis included diagnosis, type of surgery (palliative vs. corrective) and age at surgery. Predetermined primary outcomes were represented by conduit failure or dysfunction. Two patients with Matrix P and two with Matrix P Plus died in the early post-operatively phase (4.3%). None of the deaths were conduit-related. One patient died at conduit replacement. Thirty-three patients (35.5%) experienced conduit failure whereas conduit dysfunction occurred in 27 patients (29%). Two-year freedom from conduit failure and dysfunction was 60.2% (95% CI: 50.1-69.6) and 77.4% (95% CI: 67.9-84.7), respectively. Reasons for failure were conduit stenosis in 20 cases (61%), pseudoaneurysm in 3 (9%), conduit dilatation (>50% of original diameter) in 2 (6%), stenosis of distal anastomosis involving pulmonary bifurcation in 6 (18%) and allograft dissection in 2 (6%). Histological examination showed inflammatory giant-type cells in the presence of a poor autologous cell seeding in all explanted specimens. Univariate and multivariate analyses showed an association between age at surgery ≤1 year and conduit dysfunction

  20. Aptitude visuelle à la conduite automobile: exemple des candidats au permis de conduire à Libreville

    Science.gov (United States)

    Souhail, Hassane; Assoumou, Prudence; Birinda, Hilda; Mengome, Emmanuel Mve

    2015-01-01

    L'objectif était d’évaluer l'aptitude visuelle à la conduite automobile des candidats au permis de conduire à Libreville. Il s'agissait d'une étude transversale, descriptive et analytique, qui s'est déroulée à Libreville pendant la période du 4 avril 2012 au 14 juillet 2012 (soit 4 mois et 10 jours). La population d’étude concernait les candidats soumis aux épreuves d'obtention du permis de conduire. Nous avons inclus dans notre travail, les candidats, ayant donné leur consentement par écrit et exclus ceux refusant d'adhérer à l'enquête. Les variables étudiées concernaient l’âge, le sexe, la population d’étude, l'activité professionnelle, l'acuité visuelle de loin et de près, la vision des couleurs, la catégorie du permis de conduire, et l'aptitude visuelle à la conduite automobile. La saisie et l'analyse des données ont été collectées au moyen d'une fiche d'enquête standardisée; après vérification et validation, elles ont été saisies sur le logiciel Excel Windows et analysées sur le logiciel Epi Info version 3.5.1. L’âge moyen des 406 candidats était de 29 ans ± 6,65 ans avec des extrêmes allant de 17 ans à 52 ans. Les hommes représentaient 283 (69,7%) et les femmes 123 (30,3%), soit un ratio de 2,3. Les fonctionnaires étaient retrouvés dans 39,4 % des cas, suivi des élèves-étudiants dans 33,5%. Dans notre population d’étude, 71 sur 406 candidats avaient une baisse de l'acuité visuelle de loin, soit 17,5%. Dans notre série, nous avons retrouvés 34 candidats âgés de 40 ans et plus, et seulement 14 candidats (41,2%) avaient une baisse de l'acuité visuelle de près. La quasi-totalité des patients avaient une vision de couleurs normale (99,5%), cependant 2 candidats avaient une vision de couleurs anormale, soit une prévalence de 0,5%. Dans notre échantillon, 403 (99,3%) sollicitaient un permis de conduire de catégorie léger (perms A, A1, B, F) et 3 (0,7%) sollicitaient un permis de conduire de type

  1. Inactive supply wells as conduits for flow and contaminant migration: conditions of occurrence and suggestions for management

    Science.gov (United States)

    Gailey, Robert M.

    2017-11-01

    Water supply wells can act as conduits for vertical flow and contaminant migration between water-bearing strata under common hydrogeologic and well construction conditions. While recognized by some for decades, there is little published data on the magnitude of flows and extent of resulting water quality impacts. Consequently, the issue may not be acknowledged widely enough and the need for better management persists. This is especially true for unconsolidated alluvial groundwater basins that are hydrologically stressed by agricultural activities. Theoretical and practical considerations indicate that significant water volumes can migrate vertically through wells. The flow is often downward, with shallow groundwater, usually poorer in quality, migrating through conduit wells to degrade deeper water quality. Field data from locations in California, USA, are presented in combination with modeling results to illustrate both the prevalence of conditions conducive to intraborehole flow and the resulting impacts to water quality. Suggestions for management of planned wells include better enforcement of current regulations and more detailed consideration of hydrogeologic conditions during design and installation. A potentially greater management challenge is presented by the large number of existing wells. Monitoring for evidence of conduit flow and solute transport in areas of high well density is recommended to identify wells that pose greater risks to water quality. Conduit wells that are discovered may be addressed through approaches that include structural modification and changes in operations.

  2. 26 CFR 1.67-3T - Allocation of expenses by real estate mortgage investment conduits (temporary).

    Science.gov (United States)

    2010-04-01

    ... 26 Internal Revenue 2 2010-04-01 2010-04-01 false Allocation of expenses by real estate mortgage... Income, Adjusted Gross Income, and Taxable Income § 1.67-3T Allocation of expenses by real estate... real estate mortgage investment conduit or REMIC (as defined in section 860D) shall allocate to each of...

  3. Intra wire resistance and strain affecting the transport properties of Nb3Sn strands in cable-in-conduit conductors

    NARCIS (Netherlands)

    Zhou, Chao

    2014-01-01

    The aim of this thesis work is to arrive at a deeper understanding of the effects of strain and filament fracture on the electric properties of superconducting strands and cable-in-conduit conductors that are subjected to various mechanical loads. Since inter-filamentary current redistribution plays

  4. Cable-in-conduit superconductors for fusion magnets: electro-magnetic modelling for understanding and optimizing their transport properties

    NARCIS (Netherlands)

    Rolando, G.

    2013-01-01

    Cable-In-Conduit conductors feature large current-carrying capacity and stability against local and transient heat deposition. As such they are suitable for application in superconducting magnets for nuclear fusion, as the ones of the International Thermonuclear Experimental Reactor (ITER). Due to

  5. Chitosan conduit combined with hyaluronic acid prevent sciatic nerve scar in a rat model of peripheral nerve crush injury.

    Science.gov (United States)

    Li, Runxin; Liu, Huawei; Huang, Haitao; Bi, Wenting; Yan, Rongzeng; Tan, Xinying; Wen, Weisheng; Wang, Chao; Song, Wenling; Zhang, Yanhua; Zhang, Feng; Hu, Min

    2018-03-01

    In the present study, the effects of hyaluronic acid (HA) combined with chitosan conduit on peripheral nerve scarring and regeneration were investigated in a rat model of peripheral nerve crush injury. A total of 60 Sprague-Dawley rats were randomly distributed into four groups (15 rats in each group), in which the nerve was either not treated (control group) or treated with chitosan conduit, hyaluronic acid, or chitosan conduit coupled with hyaluronic acid following clamp injury to the sciatic nerve. The surgical sites were evaluated by assessing the sciatic functional index, the degree of scar adhesions, the numbers of myelinated nerve fibers, the average diameter of myelinated nerve fibers and the myelin sheath thickness. Larger epineurial scar thickness was observed in the control groups compared with the treatment groups at 4, 8 and 12 weeks following surgery. There was no significant difference in scar adhesion among the four groups at 4 weeks following surgery. However, animals receiving chitosan coupled with HA demonstrated better neural recovery, as measured by reduced nerve adherence to surrounding tissues, less scar adhesion, increased number of axons, nerve fiber diameter and myelin thickness. In conclusion, the application of chitosan conduit combined with HA, to a certain extent, inhibited sciatic nerve extraneural scaring and adhesion, and promoted neural regeneration and recovery.

  6. Failing left ventricle to ascending aorta conduit-Hybrid implantation of a melody valve and NuMed covered stent.

    Science.gov (United States)

    Gössl, Mario; Johnson, Jonathan N; Hagler, Donald J

    2014-04-01

    We present the case of a 36-year-old woman with increasing shortness of breath, a new 3/4 diastolic murmur, and a complex history of LV outflow tract obstruction. She has undergone multiple surgeries including the replacement of her old LV apex to ascending aorta conduit with a 20-mm Gore-Tex tube graft, addition of a 24-mm homograft sutured between the conduit and the LV apex, and insertion of a 21-mm Freestyle porcine valve conduit between the Gore-Tex tube graft and allograft at age 23. The current assessment showed a failing Freestyle conduit prosthesis leading to left heart decompensation. Due to substantial surgical risk, the patient underwent successful implantation of a Melody valve into the Gore-Tex tube and exclusion of the failing Freestyle bioprosthesis with a NuMed CP stent in a hybrid procedure. The case nicely illustrates the collaborative potential of cardiovascular surgeons and interventional cardiologists in the new arena of a hybrid operating room. Complex hybrid procedures like the current one, especially those including percutaneous placements of valves, offer therapeutic options for patients that are otherwise too high risk for conventional open heart surgery. Copyright © 2013 Wiley Periodicals, Inc.

  7. The influence of Lorentz force on the ac loss in sub-size cable-in-conduit conductors for ITER

    NARCIS (Netherlands)

    Nijhuis, Arend; ten Kate, Herman H.J.; Bruzzone, Pierluigi

    1997-01-01

    The cable-in-conduit superconductors for the ITER coils have operating current in excess of 40 kA and function under last ramp conditions and fields up to 13 T. The transverse Lorentz force acting on strands may reduce the effective contact resistance between strands in the cable and as a

  8. Creation of gastric conduit free-graft with intraoperative perfusion imaging during pancreaticoduodenectomy in a patient post esophagectomy

    Directory of Open Access Journals (Sweden)

    Spyridon Pagkratis

    2015-01-01

    She underwent open pancreaticoduodenectomy, and to maintain perfusion to the gastric conduit a microvascular anastomosis of the gastroepiploic pedicle was performed to the middle colic vessels. Intraoperative fluorescent imaging was used to evaluate the anastomosis as well as gastric and duodenal perfusion during the case.

  9. Diagnostic criteria for vascular dementia

    NARCIS (Netherlands)

    Scheltens, P.; Hijdra, A. H.

    1998-01-01

    The term vascular dementia implies the presence of a clinical syndrome (dementia) caused by, or at least assumed to be caused by, a specific disorder (cerebrovascular disease). In this review, the various sets of criteria used to define vascular dementia are outlined. The various sets of criteria

  10. Dynamic adaption of vascular morphology

    DEFF Research Database (Denmark)

    Okkels, Fridolin; Jacobsen, Jens Christian Brings

    2012-01-01

    The structure of vascular networks adapts continuously to meet changes in demand of the surrounding tissue. Most of the known vascular adaptation mechanisms are based on local reactions to local stimuli such as pressure and flow, which in turn reflects influence from the surrounding tissue. Here ...

  11. Caffeine's Vascular Mechanisms of Action

    Directory of Open Access Journals (Sweden)

    Darío Echeverri

    2010-01-01

    Full Text Available Caffeine is the most widely consumed stimulating substance in the world. It is found in coffee, tea, soft drinks, chocolate, and many medications. Caffeine is a xanthine with various effects and mechanisms of action in vascular tissue. In endothelial cells, it increases intracellular calcium stimulating the production of nitric oxide through the expression of the endothelial nitric oxide synthase enzyme. Nitric oxide is diffused to the vascular smooth muscle cell to produce vasodilation. In vascular smooth muscle cells its effect is predominantly a competitive inhibition of phosphodiesterase, producing an accumulation of cAMP and vasodilation. In addition, it blocks the adenosine receptors present in the vascular tissue to produce vasoconstriction. In this paper the main mechanisms of action of caffeine on the vascular tissue are described, in which it is shown that caffeine has some cardiovascular properties and effects which could be considered beneficial.

  12. The Danish Vascular Registry, Karbase

    DEFF Research Database (Denmark)

    Eldrup, Nikolaj; Cerqueira, Charlotte; de la Motte, Louise

    2016-01-01

    AIM: The Danish Vascular Registry (DVR), Karbase, is monitoring arterial and advanced vein interventions conducted at all vascular departments in Denmark. The main aim of the DVR is to improve the quality of treatment for patients undergoing vascular surgery in Denmark by using the registry...... for quality assessment and research. STUDY POPULATION: All patients undergoing vascular interventions (surgical and endovascular) at any vascular department in Denmark are registered in the DVR. The DVR was initiated in 1989, and each year, ∼9,000 procedures are added. By January 2016, >180,000 procedures...... have been recorded. Since 2001, data completeness has been >90% (compared to the Danish National Patient Register). MAIN VARIABLES: Variables include information on descriptive patient data (ie, age, sex, height, and weight) and comorbidity (ie, previous cardiovascular disease and diabetes). Process...

  13. Social media in vascular surgery.

    Science.gov (United States)

    Indes, Jeffrey E; Gates, Lindsay; Mitchell, Erica L; Muhs, Bart E

    2013-04-01

    There has been a tremendous growth in the use of social media to expand the visibility of various specialties in medicine. The purpose of this paper is to describe the latest updates on some current applications of social media in the practice of vascular surgery as well as existing limitations of use. This investigation demonstrates that the use of social networking sites appears to have a positive impact on vascular practice, as is evident through the incorporation of this technology at the Cleveland Clinic and by the Society for Vascular Surgery into their approach to patient care and physician communication. Overall, integration of social networking technology has current and future potential to be used to promote goals, patient awareness, recruitment for clinical trials, and professionalism within the specialty of vascular surgery. Copyright © 2013 Society for Vascular Surgery. Published by Mosby, Inc. All rights reserved.

  14. Bioabsorbable nerve conduits coated with induced pluripotent stem cell-derived neurospheres enhance axonal regeneration in sciatic nerve defects in aged mice.

    Science.gov (United States)

    Yokoi, Takuya; Uemura, Takuya; Takamatsu, Kiyohito; Shintani, Kosuke; Onode, Ema; Okada, Mitsuhiro; Hidaka, Noriaki; Nakamura, Hiroaki

    2017-09-09

    Aging influences peripheral nerve regeneration. Nevertheless, most basic research of bioabsorbable nerve conduits including commercial products have been performed in very young animals. Results from these studies may not provide information about axonal regeneration in aged tissue, because young nerve tissue holds sufficient endogenous potential for axonal regeneration. The clinical target age for nerve conduit application is most likely going to increase with a rapidly growing elderly population. In the present study, we examined axonal regeneration after sciatic nerve defects in aged and young mice. 5-mm sciatic nerve defects in young (6 weeks old) and aged (92 weeks old) mice were reconstructed using nerve conduits (composed of a poly lactide and caprolactone) or autografts. In addition, in aged mice, sciatic nerve defects were reconstructed using nerve conduits coated with mouse induced pluripotent stem cell (iPSc)-derived neurospheres. Using electrophysiological and histological techniques, we demonstrated axonal regeneration was significantly less effective in aged than in young mice both for nerve conduits and for nerve autografts. However, despite the low regenerative capacity of the peripheral nerve in aged mice, axonal regeneration significantly increased when nerve conduits coated with iPSc-derived neurospheres, rather than nerve conduits alone, were used. The present study shows that aging negatively affects peripheral nerve regeneration based on nerve conduits in mice. However, axonal regeneration using nerve conduits was improved when supportive iPSc-derived neurospheres were added in the aged mice. We propose that tissue-engineered bioabsorbable nerve conduits in combination with iPSc-derived neurospheres hold therapeutic potential both in young and elderly patients. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2017. © 2017 Wiley Periodicals, Inc.

  15. Noninfarct vascular dementia and Alzheimer dementia spectrum.

    Science.gov (United States)

    Emery, V Olga; Gillie, Edward X; Smith, Joseph A

    2005-03-15

    Vascular dementia is an overarching superordinate category of which multiinfarct vascular dementia is only one subtype. To contribute to the definition of vascular dementia, method involved investigation of mental status, oral language and comprehension in 81 consecutive vascular patients comprising two vascular samples: cerebral infarct sample (n=43) and cerebral noninfarct sample (n=38). To determine baseline, method also involved investigation of 36 demographically equivalent normal elderly. Results indicate both vascular samples performed significantly worse than normal elderly. Results further indicate there were no robust, reliable, significant differences between cerebral infarct and cerebral noninfarct patients. The lack of significant differences between cerebral infarct and cerebral noninfarct vascular samples brings into focus the ambiguous transition between diffuse, generalized disease and the multifocality underlying the vascular dementia-Alzheimer dementia spectrum. Cross-cutting infarct and noninfarct vascular populations were vascular factors of arteriosclerosis, abnormal blood pressure, diabetes mellitus, abnormal electrocardiogram, peripheral vascular disease, and other variables implicated in the distal causality of both infarct and noninfarct vascular dementias. Results indicate cerebral infarction is not the only path to the final common phenotype of vascular dementia. Vascular dementia is reconceptualized so as to include noninfarct vascular dementia: vascular dementia caused by underlying vascular factors other than cerebral infarction. It is suggested that one form of the subtype of noninfarct vascular dementia is Alzheimer-type vascular dementia.

  16. Dynamics within geyser conduits: Insights from downhole measurements in El Jefe geyser, El Tatio Geyser Field, Chile

    Science.gov (United States)

    Munoz Saez, C.; Manga, M.; Hurwitz, S.; Rudolph, M. L.; Namiki, A.; Wang, C.; King, E.; Patel, A.

    2013-12-01

    The El Tatio geothermal area is located in the Atacama Desert at an elevation of 4200 m asl. It is the third largest geyser field in the world, with more than 100 active geysers. Recharge of meteoric waters from the NE is limited, and temperatures vary daily from -5 to 10 C. We studied a geyser that we named 'El Jefe' (601768 E, 7530174 S, WGS84 19S). Its conduit has a constriction at a depth of 1.5 m and its diameter is 30 cm. Erupted water ponds in a natural pool around the conduit, and a large fraction then flows back into to the conduit at the end of the eruption. To quantify the mechanics and thermodynamics of the geyser's eruptions, we measured temperature, and pressure continuously inside the geyser conduit for 7 days. Pressure was measured at three depths at a frequency of 100 Hz and temperature was measured at depth intervals of 30 cm at a frequency of 1Hz. During the period of our study, eruption duration was 25 +/- 1.5 seconds and the interval between eruptions was 132 +/-2.5 sec. Variations of the eruption duration and intervals did not correlate with atmospheric pressure and temperature variations. The eruption cycle consists of four distinct stages: (1) Pre-play: lasts for 15 seconds prior to the surface manifestation of the eruption. (2) Eruption: lasts for 25 seconds (3) Post-eruption relaxation: pressure decreases rapidly in two steps, but temperature decreases gradually lagging behind the pressure decrease. Erupted water is drained into the conduit. (4) Recharge: temperature remains nearly constant while pressure increases, suggesting recharge of cold water from below.

  17. Phenotypic changes of Schwann cells on the proximal stump of injured peripheral nerve during repair using small gap conduit tube

    Directory of Open Access Journals (Sweden)

    Shi-jun Zhang

    2017-01-01

    Full Text Available Dedifferentiation of Schwann cells is an important feature of the response to peripheral nerve injury and specific negative myelination regulators are considered to have a major role in this process. However, most experiments have focused on the distal nerve stump, where the Notch signaling pathway is strongly associated with Schwann cell dedifferentiation and repair of the nerve. We observed the phenotypic changes of Schwann cells and changes of active Notch signaling on the proximal stump during peripheral nerve repair using small gap conduit tubulization. Eighty rats, with right sciatic nerve section of 4 mm, were randomly assigned to conduit bridging group and control group (epineurium suture. Glial fibrillary acidic protein expression, in myelinating Schwann cells on the proximal stump, began to up-regulate at 1 day after injury and was still evident at 5 days. Compared with the control group, Notch1 mRNA was expressed at a higher level in the conduit bridging group during the first week on the proximal stump. Hes1 mRNA levels in the conduit bridging group significantly increased compared with the control group at 3, 5, 7 and 14 days post-surgery. The change of the Notch intracellular domain shared a similar trend as Hes1 mRNA expression. Our results confirmed that phenotypic changes of Schwann cells occurred in the proximal stump. The differences in these changes between the conduit tubulization and epineurium suture groups correlate with changes in Notch signaling. This suggests that active Notch signaling might be a key mechanism during the early stage of neural regeneration in the proximal nerve stump.

  18. Recruiting women to vascular surgery and other surgical specialties.

    Science.gov (United States)

    Dageforde, Leigh Anne; Kibbe, Melina; Jackson, Gretchen Purcell

    2013-01-01

    Vascular surgery is a subspecialty that attracts future surgeons with challenging technical procedures and complex decision making. Despite its appeal, continued promotion of the field is necessary to recruit and retain the best and brightest candidates. Recruitment of medical students and residents may be limited by the lifestyle inherent to vascular surgery and the length of residency training. The young adults of the current applicant and resident pool differ from prior generations in their desire for hands-on mentoring, aspirations to affect change daily, a penchant for technology, and strong emphasis on work-life balance. Furthermore, the percentage of women pursuing careers in vascular surgery is not representative of the eligible workforce. Women are now the majority of graduates in all of higher education, and thus, vascular surgery may need to make a concerted effort to appeal to women in order to attract the most talented young professionals to the field. Recruiting strategies for both men and women of Generation Y should target a diverse group of potential candidates with an awareness of the unique characteristics and needs of this generation of rising surgeons. Copyright © 2013 Society for Vascular Surgery. All rights reserved.

  19. Contemporary vascular smartphone medical applications.

    Science.gov (United States)

    Carter, Thomas; O'Neill, Stephen; Johns, Neil; Brady, Richard R W

    2013-08-01

    Use of smartphones and medical mHealth applications (apps) within the clinical environment provides a potential means for delivering elements of vascular care. This article reviews the contemporary availability of apps specifically themed to major vascular diseases and the opportunities and concerns regarding their integration into practice. Smartphone apps relating to major vascular diseases were identified from the app stores for the 6 most popular smartphone platforms, including iPhone, Android, Blackberry, Nokia, Windows, and Samsung. Search terms included peripheral artery (arterial) disease, varicose veins, aortic aneurysm, carotid artery disease, amputation, ulcers, hyperhydrosis, thoracic outlet syndrome, vascular malformation, and lymphatic disorders. Forty-nine vascular-themed apps were identified. Sixteen (33%) were free of charge. Fifteen apps (31%) had customer satisfaction ratings, but only 3 (6%) had greater than 100. Only 13 apps (27%) had documented medical professional involvement in their design or content. The integration of apps into the delivery of care has the potential to benefit vascular health care workers and patients. However, high-quality apps designed by clinicians with vascular expertise are currently lacking and represent an area of concern in the mHealth market. Improvement in the quality and reliability of these apps will require the development of robust regulation. Copyright © 2013 Elsevier Inc. All rights reserved.

  20. Depression in vascular dementia.

    Science.gov (United States)

    Naarding, Paul; de Koning, Inge; dan Kooten, Fop; Dippel, Diederik W J; Janzing, Joost G E; van der Mast, Rose C; Koudstaal, Peter J

    2003-04-01

    To study the presence of different dimensions of depression in subjects with vascular dementia. After a stroke, cognitive, affective and behavioural disturbances are common. It has been suggested that the nature of affective symptomatology can help to differentiate organic from psychological depression. Cognitive and affective symptoms were assessed in 78 stroke patients and a principal component analysis was performed on these symptoms. Also, a discriminant analysis was carried out to establish the contribution of different symptoms on the diagnosis 'depressive disorder' and 'dementia'. (1) Principal component analysis revealed three distinct sub-syndromes: one with predominantly mood symptoms, one with essentially psychomotor symptoms, and one with vegetative symptoms; (2) mood, psychomotor and vegetative symptoms were all independently and strongly related to a diagnosis of major depressive disorder according to DSM-III-R criteria; (3) the psychomotor factor was also firmly associated with dementia; and (4) discriminant analysis gave further support for our conclusion that some of the depressive features, in particular the psychomotor factor, are at least partly related to the organic brain damage from stroke. The results indicate that different dimensions of depression could be discerned in a group of stroke patients and that the symptom profile of depression in these patients can be affected by the presence of dementia. Copyright 2003 John Wiley & Sons, Ltd.

  1. [Extremity vascular traumas].

    Science.gov (United States)

    Angelini, Romeo; Rutolo, Ferdinando; Cozzolino, Giuseppe; D'Amario, Vanessa; Spigonardo, Francesca

    2005-01-01

    The Authors report on a series of 61 vascular traumas treated over a 7 years, separated in two groups. The first one includes 35 cases, that are street accidents, on the work and gunshot wounds. The second group includes 26 iatrogenic causes due to arterial catheterism. All patients underwent ecocolor Doppler directly in the operating theatre and, when this diagnostic procedure was not enough, pre-operating angiography was used (10 cases of complex traumas of the lower limb). One death was reported far each groups (3.27%). In 55 cases (90.1%), limb savage was achieved. In the others 4 (6.93%) of the first group, limb demolition was necessary for different causes. In the first group, severe neurological sequelaes were observed in 2 cases and motor deficits caused by tendon lesions in 1 case. The good results obtained are the result of the short ischemic interval between the acute event and treatment, thanks to a multidisciplinary approach of a specific equipe, that is rapid as possible.

  2. Long-Term Regeneration and Functional Recovery of a 15 mm Critical Nerve Gap Bridged by Tremella fuciformis Polysaccharide-Immobilized Polylactide Conduits

    Directory of Open Access Journals (Sweden)

    Shan-hui Hsu

    2013-01-01

    Full Text Available Novel peripheral nerve conduits containing the negatively charged Tremella fuciformis polysaccharide (TF were prepared, and their efficacy in bridging a critical nerve gap was evaluated. The conduits were made of poly(D,L-lactide (PLA with asymmetric microporous structure. TF was immobilized on the lumen surface of the nerve conduits after open air plasma activation. The TF-modified surface was characterized by the attenuated total reflection Fourier-transformed infrared spectroscopy and the scanning electron microscopy. TF modification was found to enhance the neurotrophic gene expression of C6 glioma cells in vitro. TF-modified PLA nerve conduits were tested for their ability to bridge a 15 mm gap of rat sciatic nerve. Nerve regeneration was monitored by the magnetic resonance imaging. Results showed that TF immobilization promoted the nerve connection in 6 weeks. The functional recovery in animals receiving TF-immobilized conduits was greater than in those receiving the bare conduits during an 8-month period. The degree of functional recovery reached ~90% after 8 months in the group of TF-immobilized conduits.

  3. Acceleration of peripheral nerve regeneration using nerve conduits in combination with induced pluripotent stem cell technology and a basic fibroblast growth factor drug delivery system.

    Science.gov (United States)

    Ikeda, Mikinori; Uemura, Takuya; Takamatsu, Kiyohito; Okada, Mitsuhiro; Kazuki, Kenichi; Tabata, Yasuhiko; Ikada, Yoshito; Nakamura, Hiroaki

    2014-05-01

    Various modifications including addition of Schwann cells or incorporation of growth factors with bioabsorbable nerve conduits have been explored as options for peripheral nerve repair. However, no reports of nerve conduits containing both supportive cells and growth factors have been published as a regenerative therapy for peripheral nerves. In the present study, sciatic nerve gaps in mice were reconstructed in the following groups: nerve conduit alone (control group), nerve conduit coated with induced pluripotent stem cell (iPSc)-derived neurospheres (iPSc group), nerve conduit coated with iPSc-derived neurospheres and basic fibroblast growth factor (bFGF)-incorporated gelatin microspheres (iPSc + bFGF group), and autograft. The fastest functional recovery and the greatest axon regeneration occurred in the autograft group, followed in order by the iPSc + bFGF group, iPSc group, and control group until 12 weeks after reconstruction. Thus, peripheral nerve regeneration using nerve conduits and functional recovery in mice was accelerated by a combination of iPSc-derived neurospheres and a bFGF drug delivery system. The combination of all three fundamental methodologies, iPSc technology for supportive cells, bioabsorbable nerve conduits for scaffolds, and a bFGF drug delivery system for growth factors, was essential for peripheral nerve regenerative therapy. Copyright © 2013 Wiley Periodicals, Inc.

  4. Modeling spatially and temporally varied hydraulic behavior of a folded karst system with dominant conduit drainage at catchment scale, Hochifen-Gottesacker, Alps

    Science.gov (United States)

    Chen, Zhao; Goldscheider, Nico

    2014-06-01

    Karst aquifers are important for freshwater supply, but difficult to manage, due to highly variable water levels and spring discharge rates. Conduits are crucial for groundwater flow in karst aquifers, but their location is often unknown, thus limiting the applicability and validity of numerical models. We have applied a conduit model (SWMM) to simulate highly variable flow in a folded alpine karst aquifer system, where the underground drainage pattern is comparatively well-known from previous tracer studies. The conduit model was coupled with a reservoir model representing recharge, storage and transfer of water in the epikarst and unsaturated zone. The global optimization approach (GA) was applied to achieve an efficient model calibration. It was possible to simultaneously simulate the highly variable discharge characteristics of an estavelle, and overflow spring and a permanent spring draining the conduit system. The model allowed for the collection of spatially differentiated information on recharge, rapid flow and slow flow in four individual sub-catchments. The formation of backwater upgradient from conduit restrictions turned out to be a key process in activating overflow springs. The proposed modeling approach appears to be transferrable to other karst systems with predominant conduit drainage, but requires previous knowledge of the configuration of the conduit system.

  5. Vascular injuries during gynecological laparoscopy: the vascular surgeon's advice

    Directory of Open Access Journals (Sweden)

    Marcello Barbosa Barros

    Full Text Available CONTEXT: Iatrogenic vascular problems due to laparoscopy are a well recognized problem and lead to significant repercussions. In this context, a ten-year review of cases topic is presented, based on experience gained while heading two important vascular surgery services. CASES: Five patients with vascular injuries during elective laparoscopy are described. These patients presented with seven lesions of iliac vessels. All cases were evaluated immediately and required laparotomy, provisional hemostasis and urgent attendance by a vascular surgeon. Direct suturing was performed in three cases. One aortoiliac bypass and one ilioiliac reversed venous graft were made. Venous lesions were sutured. One case of a point-like perforation of the small bowel was found. There were no deaths and no complications during the postoperative period. DISCUSSION: Important points on this subject are made, and advice is given. There needs to be immediate recognition of the vascular injury, and expert repair by a vascular surgeon is recommended, in order to significantly reduce the degree of complications.

  6. Trauma vascular, visión del cirujano vascular

    Directory of Open Access Journals (Sweden)

    Dr. D. Cristián Salas

    2011-09-01

    Full Text Available El 3% de todas las lesiones en trauma tiene un componente vascular. Con los conflictos armados del siglo pasado se lograron grandes avances en este campo. A partir de la Guerra de Vietnam gracias a las mejoras en el manejo prehospitalario, traslado de pacientes, y avances en técnica quirúrgica se lograron tasas de sobrevida y de amputaciones que se han mantenido estables hasta la fecha. El diagnóstico de lesiones vasculares en extremidades se realiza con el examen físico, sin embargo las lesiones de vasos torácicos y abdominales requieren de imágenes de apoyo, siempre que el paciente se encuentre estabilizado, generalmente tomografía axial computada. La mayoría de las lesiones vasculares son por trauma penetrante, comprometiendo principalmente las extremidades. Con el desarrollo de los procedimientos invasivos vasculares en los últimos años se ha observado un aumento de lesiones vasculares iatrogénicas. Hoy en día muchos pacientes con trauma vascular son manejados por vía endovascular.

  7. Role of preoperative vascular ultrasonography in hemodialysis vascular access operation.

    Science.gov (United States)

    Siribumrungwong, Boonying; Tomtitchong, Prakitpunthu; Kanpirom, Kitti

    2010-12-01

    Preoperative vascular mapping increase rate of successful hemodialysis vascular access operation. Several studies recommend using this procedure routinely. But some studies recommend using this procedure in selected patients. So this study aims to determine the impacts of preoperative vascular mapping in unfavorable-examined patients. 55 patients were studied retrospectively from August 2006 to October 2009. Before April 2008, the operative plans were based on physical examination (group 1). After April 2008, the surgeon did preoperative vascular mapping prior to the operation in unfavorable-examined patients (group 2). The results were compared. There were high maturation rates in favorable-examined patients. In unfavorable-examined patients, preoperative vascular mapping can identified nonpalpable favorable vein which successful maturation of 18.75%. Complementary duplex scan decrease rate of unsuccessful operation significantly (p = 0.037) but does not increase maturation rate. Careful physical examination is important part before operation. Preoperative vascular mapping has benefit only in patients with unfavorable-examined patients. It finds some nonpalpable favorable vein and decrease unsuccessful exploration.

  8. Stem cell-derived vascular endothelial cells and their potential application in regenerative medicine

    Science.gov (United States)

    Although a 'vascular stem cell' population has not been identified or generated, vascular endothelial and mural cells (smooth muscle cells and pericytes) can be derived from currently known pluripotent stem cell sources, including human embryonic stem cells and induced pluripotent stem cells. We rev...

  9. Diabetes and Retinal Vascular Dysfunction

    Directory of Open Access Journals (Sweden)

    Eui Seok Shin

    2014-01-01

    Full Text Available Diabetes predominantly affects the microvascular circulation of the retina resulting in a range of structural changes unique to this tissue. These changes ultimately lead to altered permeability, hyperproliferation of endothelial cells and edema, and abnormal vascularization of the retina with resulting loss of vision. Enhanced production of inflammatory mediators and oxidative stress are primary insults with significant contribution to the pathogenesis of diabetic retinopathy (DR. We have determined the identity of the retinal vascular cells affected by hyperglycemia, and have delineated the cell autonomous impact of high glucose on function of these cells. We discuss some of the high glucose specific changes in retinal vascular cells and their contribution to retinal vascular dysfunction. This knowledge provides novel insight into the molecular and cellular defects contributing to the development and progression of diabetic retinopathy, and will aid in the development of innovative, as well as target specific therapeutic approaches for prevention and treatment of DR.

  10. ( Elaeis guineensis Jacq ) vascular wilt

    African Journals Online (AJOL)

    Effet de la jachére sur l'expérimentation de la fusariose vasculaire du palmier à huile ( Elaeis guineensis Jacq ) : Effects of the fallow in the expression of oil-palm ( Elaeis guineensis Jacq ) vascular wilt.

  11. Heritability of Retinal Vascular Fractals

    DEFF Research Database (Denmark)

    Vergmann, Anna Stage; Broe, Rebecca; Kessel, Line

    2017-01-01

    Purpose: To determine the genetic contribution to the pattern of retinal vascular branching expressed by its fractal dimension. Methods: This was a cross-sectional study of 50 monozygotic and 49 dizygotic, same-sex twin pairs aged 20 to 46 years. In 50°, disc-centered fundus photographs, the reti...... vasculature may affect the retinal response to potential vascular disease in later life....

  12. The Danish Vascular Registry, Karbase

    Science.gov (United States)

    Eldrup, Nikolaj; Cerqueira, Charlotte; de la Motte, Louise; Rathenborg, Lisbet Knudsen; Hansen, Allan K

    2016-01-01

    Aim The Danish Vascular Registry (DVR), Karbase, is monitoring arterial and advanced vein interventions conducted at all vascular departments in Denmark. The main aim of the DVR is to improve the quality of treatment for patients undergoing vascular surgery in Denmark by using the registry for quality assessment and research. Study population All patients undergoing vascular interventions (surgical and endovascular) at any vascular department in Denmark are registered in the DVR. The DVR was initiated in 1989, and each year, ∼9,000 procedures are added. By January 2016, >180,000 procedures have been recorded. Since 2001, data completeness has been >90% (compared to the Danish National Patient Register). Main variables Variables include information on descriptive patient data (ie, age, sex, height, and weight) and comorbidity (ie, previous cardiovascular disease and diabetes). Process variable includes waiting time (time from event to medical contact and treatment) and the type of procedures conducted. Outcome variables for in-hospital complications (ie, wound complications, myocardial infarction, stroke, amputation, respiratory complications, and renal insufficiency) and 30-day patency are submitted. Variables for medical treatment (antithrombotic and statin treatment), amputation, and survival are extracted from nationwide, administrative registers. Conclusion The DVR reports outcome on key indicators for monitoring the quality at all vascular departments in Denmark for the purpose of quality improvement. Furthermore, data are available for research and are being used in international collaborations on changes in clinical practices. PMID:27822118

  13. [Cutaneous vascular anomalies in children].

    Science.gov (United States)

    Yilmaz, L; Kacenelenbogen, N

    2015-09-01

    Vascular anomalies, which are erroneously categorized under the term angiomas, are a highly heterogeneous group of lesions that are poorly understood and affect a mean of 5 to 10 % of children. The fortuitous discovery of propranolol's efficacy in one of these entities has made them a topical issue. The paper's main objective is to inform family doctors of the various types of vascular anomalies, clarify their classification, and provide a common terminology. Its secondary objective is to provide a decision tree that enables primary care doctors to avoid diagnostic pitfalls, successfully detect cases, and optimize management. Systematic review. According to a recent study, 71,3 % of publications use the term hemangioma erroneously, regardless of the authors' field. The key for family doctors is to use one international classification only, that of the International Society for the Study of Vascular Anomalies (ISSVA), in order to facilitate management and comprehension between the different healthcare levels. The diagnosis of vascular anomalies is clinical in 90 % of cases, so all family doctors can, whilst using a decision tree, diagnose a vascular anomaly and refer only those that are complex for specialist care. The most common vascular anomaly is infantile hemangioma in infants, which spontaneously regresses around the age of 5-7 years in 90 % of cases. Watchful waiting and regular follow-up suffice, therefore, in such settings.

  14. A new cable-in-conduit conductor magnet with insulated strands

    Energy Technology Data Exchange (ETDEWEB)

    Yamaguchi, Satarou; Yamamoto, Junya; Motojima, Osamu

    1995-09-01

    Many studies have used cable-in-conduit conductor (CICC) coils in trying to develop an AC superconducting magnet because of its enormous potential if AC losses were low and insulation voltage was high. The strands in the most recent CICC magnets are coated with chromium or another metal with high electrical resistance to order to induce current re-distribution among the strands and to avoid a quench caused by a current imbalance. Current re-distribution is highly complex and very difficult to analyze because the conditions of the strand surfaces and the contact areas vary greatly with the operation of the conductor. If, however, the cable currents were well-balanced, insulating the strands would be the best way to reduce AC losses. We propose a new CICC magnet structure featuring a current lead that balances the strand currents via its resistance. Having calculated current balances, we find that strand currents are well within the present parameters for nuclear fusion experiments and superconducting magnet energy storages. (author).

  15. The effects of fenoldopam on coronary conduit blood flow after coronary artery bypass graft surgery.

    LENUS (Irish Health Repository)

    Halpenny, M

    2012-02-03

    OBJECTIVE: To quantify the effects of fenoldopam, 0.1 microg\\/kg\\/min, on left internal mammary artery (LIMA) and saphenous vein blood flow after coronary anastomosis. DESIGN: Prospective, randomized, double-blind, placebo-controlled trial. SETTING: University teaching hospital, single institution. PARTICIPANTS: Thirty-one American Society of Anesthesiologists III patients undergoing elective coronary revascularization. INTERVENTIONS: A perivascular ultrasonic flow probe (Linton Instrumentation, Norfolk, UK) was placed around the LIMA and saphenous vein graft after coronary anastomosis. MEASUREMENTS AND MAIN RESULTS: Immediately before and at 5-minute intervals for 15 minutes after starting the infusion, blood flow was measured in the LIMA and one saphenous vein graft using a transit time ultrasonic flow probe. Heart rate, blood pressure, and central venous pressure were documented at these time points. Administration of fenoldopam, 0.1 microg\\/kg\\/min, did not alter heart rate or blood pressure. A small, nonsignificant increase in LIMA blood flow occurred during the 15-minute study period (30 +\\/- 12 to 35 +\\/- 10 mL\\/min) in patients who received fenoldopam. No significant changes occurred in the placebo group. CONCLUSIONS: The findings indicate that fenoldopam, 0.1 microg\\/kg\\/min, did not influence coronary conduit blood flow to a clinically significant extent. The small increase in LIMA blood flow may be of greater importance in high-risk patients or in the prevention of coronary arterial spasm.

  16. The side-to-side fashion for individual distal coronary anastomosis using venous conduit.

    Science.gov (United States)

    Kato, Takayoshi; Tsunekawa, Tomohiro; Motoji, Yusuke; Hirakawa, Akihiro; Okawa, Yasuhide; Tomita, Shinji

    2017-04-01

    Regarding to coronary artery bypass grafting (CABG), the end-to-side anastomosis (ESA) has been performed as a gold standard. Recently, the effectiveness of the distal side-to-side anastomosis (SSA) in CABG using internal mammary artery has been reported. The benefit of SSA comparing to ESA also has been disclosed by computing simulation. However, use of SSA by venous conduit for individual CABG has not been reported. In this study, we investigated feasibility of SSA. From January 2013 to October 2014, we conducted 114 CABGs. There were 92 venous distal anastomoses without sequential anastomotic site (61 SSA and 31 ESA). The anastomosis was evaluated before discharge and at 1 year after the procedure by angiography or multi-detector row computed tomographic coronary angiography. The median values for time to anastomosis were 13 min in the two group (p = 0.89). There was no revision of anastomosis in both groups. Additional stitches for hemostasis were required significantly less in SSA than ESA (18.0 vs 45.2 %, respectively, p fashion is easy to perform and maybe beneficial in blood flow pattern.

  17. FEMCAM Analysis of SULTAN Test Results for ITER Nb3SN Cable-conduit Conductors

    Energy Technology Data Exchange (ETDEWEB)

    Yuhu Zhai, Pierluigi Bruzzone, Ciro Calzolaio

    2013-03-19

    Performance degradation due to filament fracture of Nb3 Sn cable-in-conduit conductors (CICCs) is a critical issue in large-scale magnet designs such as ITER which is currently being constructed in the South of France. The critical current observed in most SULTAN TF CICC samples is significantly lower than expected and the voltage-current characteristic is seen to have a much broader transition from a single strand to the CICC. Moreover, most conductors exhibit the irreversible degradation due to filament fracture and strain relaxation under electromagnetic cyclic loading. With recent success in monitoring thermal strain distribution and its evolution under the electromagnetic cyclic loading from in situ measurement of critical temperature, we apply FEMCAM which includes strand filament breakage and local current sharing effects to SULTAN tested CICCs to study Nb3 Sn strain sensitivity and irreversible performance degradation. FEMCAM combines the thermal bending effect during cool down and the EM bending effect due to locally accumulating Lorentz force during magnet operation. It also includes strand filament fracture and related local current sharing for the calculation of cable n value. In this paper, we model continuous performance degradation under EM cyclic loading based on strain relaxation and the transition broadening upon cyclic loading to the extreme cases seen in SULTAN test data to better quantify conductor performance degradation.

  18. Optimization of lamp arrangement in a closed-conduit UV reactor based on a genetic algorithm.

    Science.gov (United States)

    Sultan, Tipu; Ahmad, Zeshan; Cho, Jinsoo

    2016-01-01

    The choice for the arrangement of the UV lamps in a closed-conduit ultraviolet (CCUV) reactor significantly affects the performance. However, a systematic methodology for the optimal lamp arrangement within the chamber of the CCUV reactor is not well established in the literature. In this research work, we propose a viable systematic methodology for the lamp arrangement based on a genetic algorithm (GA). In addition, we analyze the impacts of the diameter, angle, and symmetry of the lamp arrangement on the reduction equivalent dose (RED). The results are compared based on the simulated RED values and evaluated using the computational fluid dynamics simulations software ANSYS FLUENT. The fluence rate was calculated using commercial software UVCalc3D, and the GA-based lamp arrangement optimization was achieved using MATLAB. The simulation results provide detailed information about the GA-based methodology for the lamp arrangement, the pathogen transport, and the simulated RED values. A significant increase in the RED values was achieved by using the GA-based lamp arrangement methodology. This increase in RED value was highest for the asymmetric lamp arrangement within the chamber of the CCUV reactor. These results demonstrate that the proposed GA-based methodology for symmetric and asymmetric lamp arrangement provides a viable technical solution to the design and optimization of the CCUV reactor.

  19. Apparent glacially induced structural controls on limestone conduit development in Ohio Caverns, United States

    Directory of Open Access Journals (Sweden)

    Adrienne M. Watts

    2016-01-01

    Full Text Available Rock discontinuities such as bedding planes and joints are important controls on the form that caves take. We examined structural controls on the development of Ohio Caverns. The cave formed in Devonian limestone underlying a small bedrock knob (Mt. Tabor within the Interior Lowland province, United States. The area has been overridden by continental glaciation multiple times. The bedrock is pervasively fractured, with many curved and wavy near-vertical fractures showing many different orientations. In the case of Ohio Caverns, it appears that the controlling fractures in map view may not be joints sensu stricto, but rather some combination of tensile and shear (mode-1 and mode-2 fractures, probably forming in the regime transition between tensile and shear fracturing. This is easy to envision in a situation with ice advancing over this topographic high, and would result in the curved fractures that are observed in many places in the cave. It can also explain the numerous fracture directions. However, not all fractures are conduit-significant. The cave initiated on or near a single bedding plane, and the cave passages exhibit strong keyhole or plus-sign cross sections. Passage and fracture orientations are inconsistent with regionally expected directions. It is likely that mechanical, hydraulic, and thermal stresses related to glaciation caused the fracturing in Mt. Tabor. The cave then developed on this template according to local hydrologic conditions. This presents a newly documented structural template sub-type for cave development.

  20. Normal zone propagation and Thermal Hydraulic Quenchback in a cable-in-conduit superconductor

    Energy Technology Data Exchange (ETDEWEB)

    Lue, J.W.; Dresner, L.

    1993-11-01

    When a local normal zone appears in a cable-in-conduit superconductor, a slug of hot helium is produced. The pressure rises and the hot helium expands. Thus the normal zone propagation in such a conductor can be governed by the hot helium expansion, rather than the heat conduction along the conductor. The expansion of the hot helium compresses the cold helium outside of the normal zone. This raises th@ temperature of the cold helium. When the temperature rise reaches the current sharing limit, the superconductor in contact goes normal. Thus a rapid increase in normal zone propagation occur. This phenomenon is termed Thermal Hydraulic Quenchback (THQ). An experiment was performed to investigate this process. The existence of THQ was verified. Thresholds of THQ were also observed by varying the conductor current, the magnetic field, the temperature, and the initial normal zone length. When THQ occurred, normal zone propagation approaching the velocity of sound was observed. A better picture of THQ is obtained by a careful comparison of the data with analytical studies.

  1. Cecum of guinea pig is a reservoir and sigmoid is a high-resistance conduit.

    Science.gov (United States)

    Lange, W; Schulze-Delrieu, K; Lange, H; Shirazi, S; Lepsien, G

    1995-05-01

    We compared the filling responses of the cecum and the sigmoid of the guinea pig using volumes up to 60 ml and 2.5 ml, respectively. In the isolated cecum, each 1-cm increment of hydrostatic pressure above zero led to accommodation of 10 ml volume; in the sigmoid, the yield pressure (at which accommodation first occurred) was 6 cm H2O, and pressure increments up to 20 cm H2O produced volume increments of less than 0.5 ml. Resting pressure at half-maximal filling was 5.0 +/- 0.7 cm H2O for the sigmoid and 1.7 +/- 0.6 cm H2O for the cecum. K+ depolarization led to a significant upward shift in the pressure curves of both segments. Ca2+ withdrawal decreased sigmoid and cecal pressures at some volumes. Distension of the cecum triggered intermittent contractions, which began with the shortening of the teniae and were associated with low-amplitude pressures and expulsion of a 5- to 10-ml volume. Distension of the sigmoid produced propagating contractions that were associated with high-amplitude pressures and lengthening; compartmentalization in the sigmoid prevented efflux from it, and volume inflow was not affected by pressure waves. Our observations indicate that its large capacity and great distensibility make the cecum suitable for reservoir functions, whereas its narrowness and lack of distensibility make the sigmoid a high-resistance conduit.

  2. Exploring the role of lipids in intercellular conduits: breakthroughs in the pipeline

    Directory of Open Access Journals (Sweden)

    Elise eDelage

    2013-12-01

    Full Text Available It has been known for more than a century that most of the plant cells are connected to their neighbors through membranous pores perforating the cell wall, namely plasmodesmata (PDs. The recent discovery of tunneling nanotubes (TNTs, thin membrane bridges established between distant mammalian cells, suggests that intercellular communication mediated through cytoplasmic continuity could be a conserved feature of eukaryotic organisms. Although TNTs differ from PDs in their formation and architecture, both are characterized by a continuity of the plasma membrane between two cells, delimiting a nanotubular channel supported by actin-based cytoskeleton. Due to this unusual membrane organization, lipids are likely to play critical roles in the formation and stability of intercellular conduits like TNTs and PDs, but also in regulating the transfer through these structures. While it is crucial for a better understanding of those fascinating communication highways, the study of TNT lipid composition and dynamics turned out to be extremely challenging. The present review aims to give an overview of the recent findings in this context. We will also discuss some of the promising imaging approaches, which might be the key for future breakthroughs in the field and could also benefit the research on PDs.

  3. Literature Review: Double-Barrelled Wet Colostomy (One Stoma) versus Ileal Conduit with Colostomy (Two Stomas).

    Science.gov (United States)

    Gan, Jason; Hamid, Rizwan

    2017-01-01

    The aim of this literature review was to analyse the advantages and disadvantages of a traditional ileal conduit (IC) with separate colostomy technique compared to the outcomes of a double-barrelled wet colostomy (DBWC) technique. The former technique results in the formation of two stomas, and the latter results in the formation of one stoma. PubMed was searched electronically for articles on DBWC. Fifteen articles were retrieved and of them 13 were included in the literature review (350 patients). Of the articles, 3 directly compared DBWC to IC with colostomy. Review of 13 DBWC articles demonstrated perioperative mortality ranging between 0 and 11.1% and postoperative complications ranging from 0 to 100%. Three of the studies directly compared DBWC to IC with colostomy; median operating times and length of stay were shorter in DBWC patients (p colostomy technique, as it requires only one stoma. This literature review supports the use of the technically less challenging DBWC technique as a viable alternative to the traditional IC with colostomy technique. © 2016 S. Karger AG, Basel.

  4. Reverse saphenous conduit flap in small animals: Clinical applications and outcomes

    Directory of Open Access Journals (Sweden)

    Ross C. Elliott

    2014-02-01

    Full Text Available Due to the lack of skin elasticity defects of the distal hind limb can be a challenge to close. This article assesses a well-described, but completely under-used technique for closure of wounds on the distal tarsus. The technique was used with good success in six cases presenting to the Bryanston Veterinary Hospital with a wide range of underlying pathology ranging from trauma to neoplastic disease of the tarsus. All six cases were treated with a reverse saphenous conduit flap and two of them underwent radiation therapy with no adverse side effects. All cases showed excellent results with a very low degree of flap necrosis that never exceeded 15% of the total flap area. This skin flap provides an excellent treatment method that is reliable in closure of defects of the distal tarsus with few adverse effects. To the author’s knowledge there has been only one previously published report on the clinical use of this type of skin flap,even though the flap is well described in most texts.

  5. Morphology and displacement of dunes in a closed-conduit flow

    CERN Document Server

    Franklin, Erick de Moraes

    2016-01-01

    The transport of solid particles entrained by a fluid flow is frequently found in industrial applications. A better knowledge of it, is of importance to improve particle related industrial processes. When shear stresses exerted by the fluid on the bed of particles are bounded to some limits, a mobile layer of particles known as bed-load takes place in which the particles stay in contact with the fixed bed. If it takes place over a non-erodible ground, and if the particle flow rate is small enough, an initial thin continuous layer of particles becomes discontinuous and composed of isolated dunes. We present here an experimental study to understand some features of the dynamics of isolated dunes under a fluid flow using a closed-conduit experimental loop made of transparent material. Acquired data concerns mainly dune morphology and displacement velocity under different conditions: different types of beads (diameters and densities) and different water flow conditions. We observed that an initial pile of beads p...

  6. "Pit Craters", lava tubes, and open vertical volcanic conduits in Hawaii: a problem in terminology

    Directory of Open Access Journals (Sweden)

    William R. Halliday

    1998-01-01

    Full Text Available Almost from the 1849 publication of the term pit crater, volcanologists have disagreed about the parameters differentiating these features from other vertical volcanic structures. Kaluaiki is a jameo giving entry to Thurston Lava Tube in Hawaii Volcanoes National Park. Long-standing misidentification of it as a pit crater is an example of misunderstandings arising from the lack of a clear definition of pit crater. In general, pit craters are unrelated to lava tube caves genetically, but two special cases are discussed. One probably is genetically related to a rift tube deep below the surface; the other is a complex of a small pit crater with a partial rim of accreted plates plus an ordinary-seeming lava tube cave. The term pit crater should be redefined in such a way that it excludes collapses or subsidences related to ordinary superficial lava tubes and open vertical volcanic conduits. Otherwise, a non-definition like that currently listed for agglomerate may be appropriate.

  7. Mathematics as a conduit for translational research in post-traumatic osteoarthritis.

    Science.gov (United States)

    Ayati, Bruce P; Kapitanov, Georgi I; Coleman, Mitchell C; Anderson, Donald D; Martin, James A

    2017-03-01

    Biomathematical models offer a powerful method of clarifying complex temporal interactions and the relationships among multiple variables in a system. We present a coupled in silico biomathematical model of articular cartilage degeneration in response to impact and/or aberrant loading such as would be associated with injury to an articular joint. The model incorporates fundamental biological and mechanical information obtained from explant and small animal studies to predict post-traumatic osteoarthritis (PTOA) progression, with an eye toward eventual application in human patients. In this sense, we refer to the mathematics as a "conduit of translation." The new in silico framework presented in this paper involves a biomathematical model for the cellular and biochemical response to strains computed using finite element analysis. The model predicts qualitative responses presently, utilizing system parameter values largely taken from the literature. To contribute to accurate predictions, models need to be accurately parameterized with values that are based on solid science. We discuss a parameter identification protocol that will enable us to make increasingly accurate predictions of PTOA progression using additional data from smaller scale explant and small animal assays as they become available. By distilling the data from the explant and animal assays into parameters for biomathematical models, mathematics can translate experimental data to clinically relevant knowledge. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:566-572, 2017. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

  8. Vascular calcification and aortic fibrosis: a bifunctional role for osteopontin in diabetic arteriosclerosis.

    Science.gov (United States)

    Shao, Jian-Su; Sierra, Oscar L; Cohen, Richard; Mecham, Robert P; Kovacs, Attila; Wang, James; Distelhorst, Kathryn; Behrmann, Abraham; Halstead, Linda R; Towler, Dwight A

    2011-08-01

    Calcification and fibrosis reduce vascular compliance in arteriosclerosis. To better understand the role of osteopontin (OPN), a multifunctional protein upregulated in diabetic arteries, we evaluated contributions of OPN in male low-density lipoprotein receptor (LDLR)-/- mice fed a high-fat diet. OPN had no impact on high-fat diet-induced hyperglycemia, dyslipidemia, or body composition. However, OPN-/-;LDLR-/- mice exhibited an altered time-course of aortic calcium accrual-reduced during initiation but increased with progression-versus OPN+/+;LDLR-/- controls. Collagen accumulation, chondroid metaplasia, and mural thickness were increased in aortas of OPN-/-;LDLR-/- mice. Aortic compliance was concomitantly reduced. Vascular reexpression of OPN (SM22-OPN transgene) reduced aortic Col2A1 and medial chondroid metaplasia but did not affect atherosclerotic calcification, Col1A1 expression, collagen accumulation, or arterial stiffness. Dosing with the proinflammatory OPN fragment SVVYGLR upregulated aortic Wnt and osteogenic gene expression, increased aortic β-catenin, and restored early-phase aortic calcification in OPN-/-;LDLR-/- mice. OPN exerts stage-specific roles in arteriosclerosis in LDLR-/- mice. Actions phenocopied by the OPN metabolite SVVYGLR promote osteogenic calcification processes with disease initiation. OPN limits vascular chondroid metaplasia, endochondral mineralization, and collagen accumulation with progression. Complete deficiency yields a net increase in arteriosclerotic disease, reducing aortic compliance and conduit vessel function in LDLR-/- mice.

  9. Exercise and Vascular Function in Child Obesity: A Meta-Analysis.

    Science.gov (United States)

    Dias, Katrin A; Green, Daniel J; Ingul, Charlotte B; Pavey, Toby G; Coombes, Jeff S

    2015-09-01

    Conduit artery flow-mediated dilation (FMD) is a noninvasive index of preclinical atherosclerosis in humans. Exercise interventions can improve FMD in both healthy and clinical populations. This systematic review and meta-analysis aimed to summarize the effect of exercise training on FMD in overweight and obese children and adolescents as well as investigate the role of cardiorespiratory fitness (peak oxygen consumption [Vo2peak]) on effects observed. PubMed, Medline, Embase, and Cinahl databases were searched from the earliest available date to February 2015. Studies of children and/or adolescents who were overweight or obese were included. Standardized data extraction forms were used for patient and intervention characteristics, control/comparator groups, and key outcomes. Procedural quality of the studies was assessed using a modified version of the Physiotherapy Evidence Base Database scale. A meta-analysis involving 219 participants compared the mean difference of pre- versus postintervention vascular function (FMD) and Vo2peak between an exercise training intervention and a control condition. There was a significantly greater improvement in FMD (mean difference 1.54%, P exercise training compared with controls. Given the diversity of exercise prescriptions, participant characteristics, and FMD measurement protocols, varying FMD effect size was noted between trials. Exercise training improves vascular function in overweight and obese children, as indicated by enhanced FMD. Further research is required to establish the optimum exercise program for maintenance of healthy vascular function in this at-risk pediatric population. Copyright © 2015 by the American Academy of Pediatrics.

  10. Vascular function and endothelin-1: tipping the balance between vasodilation and vasoconstriction.

    Science.gov (United States)

    Nishiyama, Steven K; Zhao, Jia; Wray, D Walter; Richardson, Russell S

    2017-02-01

    Endothelin-1 (ET-1), a potent vasoconstrictor secreted by vascular endothelial cells, has been implicated in the pathophysiology of numerous cardiovascular diseases, yet the direct impact of ET-1 on vascular function remains unclear. Therefore, in seven young (23 ± 1 yr) healthy subjects, we investigated the effect of an intra-arterial infusion of ET-1 on reactive hyperemia (RH) and flow-mediated dilation (FMD) in the popliteal artery following 5 min of suprasystolic cuff occlusion. ET-1 infusion significantly attenuated basal leg blood flow (control: 62 ± 4 ml/min, ET-1: 47 ± 9 ml/min), RH [area-under-curve (AUC); control: 162 ± 15 ml, ET-1: 104 ± 16 ml], and peak RH (control: 572 ± 51 ml/min, ET-1: 412 ± 32 ml/min) (P tipping the balance between vasodilation and vasoconstriction, in favor of the latter.NEW & NOTEWORTHY Endothelin-1 (ET-1) is recognized as the body's most potent endogenous vasoconstrictor, but the impact of this peptide on vascular function is not well understood. The present study revealed that the intra-arterial administration of ET-1 impaired both microvascular and conduit vessel function of the leg in young, healthy, humans. Studies employing vascular testing in patient cohorts that experience a disease-related increase in ET-1 should thus exercise caution, as ET-1 clearly impairs vascular function. Copyright © 2017 the American Physiological Society.

  11. Catheter-based infrared light scanner as a tool to assess conduit quality in coronary artery bypass surgery.

    Science.gov (United States)

    Burris, Nicholas; Schwartz, Kimberly; Tang, Cha-Min; Jafri, M Samir; Schmitt, Joseph; Kwon, Michael H; Toshinaga, Ozeki; Gu, Junyan; Brown, Jamie; Brown, Emile; Pierson, Richard; Poston, Robert

    2007-02-01

    Endothelial disruption within saphenous vein and radial artery grafts increases thrombosis risk. However, no clinically applicable method for imaging the intima currently exists. We used a novel infrared imaging technology, optical coherence tomography (OCT; LightLab Imaging, Inc, Westford, Mass), to visualize the intima within harvested conduits. Conduits were procured endoscopically (37 saphenous vein grafts and 8 radial artery grafts) or with the open technique (9 radial artery grafts) from 50 patients. Surplus segments were analyzed by means of OCT for evidence of preexisting pathology or traumatic injury. Focal plaques in radial artery grafts and the intimal hyperplasia area in saphenous vein grafts were quantified as having an intimal/medial thickness ratio of greater than 0.5. Biopsy specimens were obtained for histologic confirmation and to analyze matrix metalloproteinase 2 levels (saphenous vein grafts) and prostacyclin/nitric oxide metabolites (radial artery grafts). Interobserver kappa coefficients and a Bland-Altman analysis were used to determine the reproducibility and accuracy of OCT interpretations. Radial artery imaging revealed plaque in 76%. Endoscopically harvested vessels showed intraluminal clot (38%) and intimal tears ranging from severe (6%) to mild (88%). In saphenous vein grafts intimal thickening was detected in 86% and intraluminal clotting in 68%. The intimal/medial thickness ratio determined by means of OCT correlated directly with matrix metalloproteinase 2 levels (R = 0.6804) in saphenous vein grafts and inversely with metabolites of prostacyclin (R = -0.55) and nitric oxide (R = -0.58) in radial artery grafts. OCT imaging was reproducible (interobserver kappa coefficients of >0.81 for the characterization of plaque types) and showed a strong correlation with histology (R = 0.8, P < .001). OCT imaging provides an accurate, real-time, and reproducible means for assessing saphenous vein graft and radial artery graft bypass conduits

  12. Material properties and electrical stimulation regimens through polycaprolactone fumarate-polypyrrole scaffolds as potential conductive nerve conduits

    OpenAIRE

    Moroder, Philipp; Wang, Huan; Ruesink, Terry; Lu, Lichun; Windebank, Anthony J.; Yaszemski, Michael J.; Runge, M. Brett

    2010-01-01

    Mechanical and electrical properties of polycaprolactone fumarate-polypyrrole (PCLF-PPy) scaffolds were studied under physiological conditions to evaluate their ability to maintain material properties necessary for application as conductive nerve conduits. PC12 cells cultured on PCLF-PPy scaffolds were stimulated with regimens of 10 μA of constant or 20 Hz frequency current passed through the scaffolds for 1 h/day. PC12 cellular morphologies were analyzed by fluorescence microscopy after 48 h...

  13. Vascular endothelial growth factor coordinates islet innervation via vascular scaffolding

    Science.gov (United States)

    Reinert, Rachel B.; Cai, Qing; Hong, Ji-Young; Plank, Jennifer L.; Aamodt, Kristie; Prasad, Nripesh; Aramandla, Radhika; Dai, Chunhua; Levy, Shawn E.; Pozzi, Ambra; Labosky, Patricia A.; Wright, Christopher V. E.; Brissova, Marcela; Powers, Alvin C.

    2014-01-01

    Neurovascular alignment is a common anatomical feature of organs, but the mechanisms leading to this arrangement are incompletely understood. Here, we show that vascular endothelial growth factor (VEGF) signaling profoundly affects both vascularization and innervation of the pancreatic islet. In mature islets, nerves are closely associated with capillaries, but the islet vascularization process during embryonic organogenesis significantly precedes islet innervation. Although a simple neuronal meshwork interconnects the developing islet clusters as they begin to form at E14.5, the substantial ingrowth of nerve fibers into islets occurs postnatally, when islet vascularization is already complete. Using genetic mouse models, we demonstrate that VEGF regulates islet innervation indirectly through its effects on intra-islet endothelial cells. Our data indicate that formation of a VEGF-directed, intra-islet vascular plexus is required for development of islet innervation, and that VEGF-induced islet hypervascularization leads to increased nerve fiber ingrowth. Transcriptome analysis of hypervascularized islets revealed an increased expression of extracellular matrix components and axon guidance molecules, with these transcripts being enriched in the islet-derived endothelial cell population. We propose a mechanism for coordinated neurovascular development within pancreatic islets, in which endocrine cell-derived VEGF directs the patterning of intra-islet capillaries during embryogenesis, forming a scaffold for the postnatal ingrowth of essential autonomic nerve fibers. PMID:24574008

  14. Efektivitas Membran Amnion Liofilisasi (Handmade Tubular sebagai Nerve Conduit pada Perbaikan Cedera Saraf Perifer Tikus dengan Gap 5 mm

    Directory of Open Access Journals (Sweden)

    R. Dadan G. Gandadikusumah

    2013-09-01

    Full Text Available Peripheral nerve injury with 5–30 mm gap which is caused by direct injury cases (87% or iatrogenic (12% become a special concern because it could cause a serious disability in the future. Therefore, we need many kinds of nerve repair methods without adding morbidity to the patient. One of the methods is entubulation method, by using natural or synthetic material. This was an animal experimental research by using simple random design in Departement Pharmachology Laboratory, Faculty of Medicine, Universitas Padjadjaran Bandung in May 2012. The samples were used 14 Wistar rats, divided into 2 groups. After creating gap on sciatic nerve, nerve conduit was installed on case group by using handmade tubular lyophilized amnion membrane. Nerve conduit was not installed in control group. After 21 days observation, conduction test and histopathology examination were done. Data were analyzed by using non-parametric statistical analysis sign test. All animals survived without any serious surgical complication. Result showed a significant difference between groups; the conduction test=0.016 (p<0.05, nerve growth to distal gap=0.063 (p<0.05, no radier direction of nerve growth=0.031 (p<0.05. Reaction of inflammation was minimum and there was no difference between two groups. In conclusion, handmade tubular lyophilized amnion membrane is effective as nerve conduit in repair of peripheral nerve injury with 5 mm gap.

  15. A Review of Bioactive Release from Nerve Conduits as a Neurotherapeutic Strategy for Neuronal Growth in Peripheral Nerve Injury

    Directory of Open Access Journals (Sweden)

    Poornima Ramburrun

    2014-01-01

    Full Text Available Peripheral nerve regeneration strategies employ the use of polymeric engineered nerve conduits encompassed with components of a delivery system. This allows for the controlled and sustained release of neurotrophic growth factors for the enhancement of the innate regenerative capacity of the injured nerves. This review article focuses on the delivery of neurotrophic factors (NTFs and the importance of the parameters that control release kinetics in the delivery of optimal quantities of NTFs for improved therapeutic effect and prevention of dose dumping. Studies utilizing various controlled-release strategies, in attempt to obtain ideal release kinetics, have been reviewed in this paper. Release strategies discussed include affinity-based models, crosslinking techniques, and layer-by-layer technologies. Currently available synthetic hollow nerve conduits, an alternative to the nerve autografts, have proven to be successful in the bridging and regeneration of primarily the short transected nerve gaps in several patient cases. However, current research emphasizes on the development of more advanced nerve conduits able to simulate the effectiveness of the autograft which includes, in particular, the ability to deliver growth factors.

  16. Field observations of extended seawater intrusion through subsurface karst conduit networks at Wakulla Spring in the Woodville Karst Plain, Florida

    Science.gov (United States)

    Xu, Z.; Bassett, S.; Hu, B. X.; Dyer, S.

    2016-12-01

    Five periods of increased electrical conductivity have been found in the karst conduits supplying one of the largest first magnitude springs in Florida with water. Numerous well-developed conduit networks are distributed in the Woodville Karst Plain (WKP), Florida and connected to the Gulf of Mexico. A composite analysis of precipitation and electric conductivity data provides strong evidence that the increases in conductivity are directly tied to seawater intrusion moving inland and traveling 14 miles against the prevailing regional hydraulic gradient from from Spring Creek Spring Complex (SCSC), a group of submarine springs at the Gulf Coast. A geochemical analysis of samples from the spring vent rules out anthropogenic contamination and upwelling regional recharge from the deep aquifer as sources of the rising conductivity. The interpretation is supported by the conceptual model established by prior researchers working to characterize the study area. This abstract documented the first and longest case of seawater intrusion in the WKP, and also indicates significant possibility of seawater contamination through subsurface conduit networks in a coastal karst aquifer.

  17. Multichanneled Nerve Guidance Conduit with Spatial Gradients of Neurotrophic Factors and Oriented Nanotopography for Repairing the Peripheral Nervous System.

    Science.gov (United States)

    Chang, Yo-Cheng; Chen, Ming-Hong; Liao, Shih-Yung; Wu, Hsi-Chin; Kuan, Chen-Hsiang; Sun, Jui-Sheng; Wang, Tzu-Wei

    2017-10-17

    Peripheral nerve injuries, causing sensory and motor impairment, affect a great number of patients annually. It is therefore important to incorporate different strategies to promote nerve healing. Among the treatment options, however, the efficacy of nerve conduits is often compromised by their lack of living cells, insufficient growth factors, and absence of the extracellular matrix (ECM)-like structure. To improve the functional recovery, we aimed to develop a natural biodegradable multichanneled scaffold characterized with aligned electrospun nanofibers and neurotrophic gradient (MC/AN/NG) to guide axon outgrowth. The gelatin-based conduits mimicked the fascicular architecture of natural nerve ECM. The multichanneled (MC) scaffolds, cross-linked with microbial transglutaminase, possessed sustainable mechanical stability. Meanwhile, the release profile of dual neurotrophic factors, nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF), exhibited a temporal-controlled manner. In vitro, the differentiated neural stem cells effectively extended their neurites along the aligned nanofibers. Besides, in the treated group, the cell density increased in high NGF concentration regions of the gradient membrane, and the BDNF significantly promoted myelination. In a rabbit sciatic nerve transection in vivo model, the MC/AN/NG scaffold showed superior nerve recovery and less muscle atrophy comparable to autograft. By integrating multiple strategies to promote peripheral nerve regeneration, the MC/AN/NG scaffolds as nerve guidance conduits showed promising results and efficacious treatment alternatives for autologous nerve grafts.

  18. Human T-cell leukemia virus type 1 p8 protein increases cellular conduits and virus transmission.

    Science.gov (United States)

    Van Prooyen, Nancy; Gold, Heather; Andresen, Vibeke; Schwartz, Owen; Jones, Kathryn; Ruscetti, Frank; Lockett, Stephen; Gudla, Prabhakar; Venzon, David; Franchini, Genoveffa

    2010-11-30

    The human T-cell leukemia virus type 1 (HTLV-1) is the cause of adult T-cell leukemia/lymphoma as well as tropical spastic paraparesis/HTLV-1-associated myelopathy. HTLV-1 is transmitted to T cells through the virological synapse and by extracellular viral assemblies. Here, we uncovered an additional mechanism of virus transmission that is regulated by the HTLV-1-encoded p8 protein. We found that the p8 protein, known to anergize T cells, is also able to increase T-cell contact through lymphocyte function-associated antigen-1 clustering. In addition, p8 augments the number and length of cellular conduits among T cells and is transferred to neighboring T cells through these conduits. p8, by establishing a T-cell network, enhances the envelope-dependent transmission of HTLV-1. Thus, the ability of p8 to simultaneously anergize and cluster T cells, together with its induction of cellular conduits, secures virus propagation while avoiding the host's immune surveillance. This work identifies p8 as a viral target for the development of therapeutic strategies that may limit the expansion of infected cells in HTLV-1 carriers and decrease HTLV-1-associated morbidity.

  19. Peritoneal pre-conditioning reduces macrophage marker expression in collagen-containing engineered vascular grafts.

    Science.gov (United States)

    Shojaee, Mozhgan; Wood, Kristin B; Moore, Lisa K; Bashur, Chris A

    2017-10-05

    Engineered vascular grafts have shown promise as arteriovenous shunts, but they have not yet progressed to clinical trials for coronary arteries synthetic material, poly(ε-caprolactone), to modulate the post-grafting inflammatory response while avoiding aneurysmal-like dilation and failure that can occur with pure collagen grafts. We also used pre-implantation in an "in vivo bioreactor" to recruit autologous cells and improve patency after grafting. Electrospun conduits were pre-implanted within rat peritoneal cavities and then grafted autologously into abdominal aortae. Conduit collagen percentages and pre-implantation were tested for their impact on graft remodeling and patency. Burst pressures >2000 mmHg, reproducible expansion with systole/diastole, and maintenance of mechanical integrity were observed. More importantly, peritoneal pre-implantation reduced overall lipid oxidation, intimal layer thickness, and expression of an M1 macrophage marker. The condition with the most collagen, 25%, exhibited the lowest expression of macrophage markers but also resulted in a thicker intimal layer. Overall, the 10% collagen/PCL with peritoneal pre-implantation condition appeared to exhibit the best combination of responses, and may result in improved clinical graft viability. This manuscript describes a rodent study to systematically determine the benefits of both pre-implantation in the peritoneal cavity and specific ratios of collagen on engineered vascular graft viability. We show that pre-implantation had a significant benefit, including decreasing the expression of macrophage markers and reducing lipid oxidation after grafting. This study is the first time that the benefits of peritoneal pre-implantation have been compared to an "off the shelf," directly grafted control condition. We also demonstrated the importance of specific collagen ratio on the response after grafting. Overall, we feel that this article will be of interest to the field and it has the

  20. Development of a discrete-continuum VDFST-CFP numerical model for simulating seawater intrusion to a coastal karst aquifer with a conduit system

    Science.gov (United States)

    Hu, Xiaolong; Xu, Zexuan

    2017-04-01

    A hybrid discrete-continuum numerical model, Variable-Density Flow and Solute Transport - Conduit Flow Process (VDFST-CFP), is developed to simulate seawater intrusion to a coastal karst aquifer with a conduit network. The Darcy-Weisbach equation is applied to simulate the non-laminar groundwater flow in the conduit system that is conceptualized as pipes, while the Darcy equation is used for laminar groundwater flow in the continuum porous medium. Density-dependent groundwater flow with appropriate additional density terms in the conduit is analytically derived. The flow equations are coupled with transport equations, and numerically solved by the finite difference method with an implicit iteration procedure. Two synthetic benchmarks are developed to compare the VDFST-CFP model results with other numerical models, such as the variable-density SEAWAT, constant-density continuum MODFLOW/MT3DMS and constant-density discrete-continuum CFPv2/UMT3D models. The VDFST-CFP model compares reasonably well with the other model results in both conduit and porous medium domains, and well describes water and salt exchanges between the two systems. Under turbulent flow conditions within the conduit, the Darcy-Weisbach equation calculates the flow rate more accurately without the overestimation by the Darcy equation . Sensitivity analysis indicates that conduit diameter, friction factor, matrix hydraulic conductivity, and effective porosity are important parameters in the VDFST-CFP model. The pros and cons of the VDFST-CFP model are discussed, including the model assumptions and simplifications, limitations of the discrete-continuum modeling method, and the convergence criteria. In general, the newly developed VDFST-CFP model provides a new numerical modeling method for simulating seawater intrusion in a coastal karst aquifer with conduits.

  1. Imaging of peripheral vascular disease

    Directory of Open Access Journals (Sweden)

    Mo Al-Qaisi

    2009-03-01

    Full Text Available Mo Al-Qaisi1, David M Nott1, David H King1, Sam Kaddoura2, Mo Hamady31Charing Cross Hospital, London, UK; 2Royal Brompton Hospital, London, UK; 3St. Mary’s Hospital, London, UKAbstract: This illustrated review article gives an evidence-based update on the different modalities used for imaging peripheral vascular disease (duplex ultrasound, computed tomography angiography, magnetic resonance angiography, and digital subtraction angiography. After discussing the latest technological developments for each modality, their limitations are also highlighted. The evidence is presented for the various modalities’ roles in the imaging of peripheral vascular disease, including problem-solving applications. The strengths and weaknesses of each modality are therefore critically appraised, including the salient technological, clinical, and financial aspects. This review allows the general and specialist practitioner to make an informed decision on how best to deploy imaging tests in peripheral vascular disease as part of an evidence-based approach. The article concludes with a rational imaging algorithm for the investigation of peripheral vascular disease.Keywords: imaging, peripheral, vascular, duplex, angiography, arterial 

  2. Optimal treatment of vascular birthmarks.

    Science.gov (United States)

    Werner, Jochen A; Dünne, Anja A; Lippert, Burkard M; Folz, Benedikt J

    2003-01-01

    Optimal functional and cosmetic outcomes for vascular lesions require a thorough preoperative diagnosis of vascular anomalies, since correct classification of each vascular lesion has a direct influence on the treatment of choice. Many different classification systems have been discussed controversially. Based on clinical practicality and significant accuracy of forecast with regard to the clinical course of a lesion, Mulliken and Glowacki's biologic classification gained most clinical relevance and has become accepted as the official classification scheme by the International Society for the Study of Vascular Anomalies (ISSVA). Based on comprehensive description of relevant literature results, the current communication shall give an overview of differing, internationally accepted treatments. Although conservative management can be proposed for uncomplicated hemangiomas occurring in infancy, the proliferative progression of these lesions provides an adequate indication for treatment, while vascular malformations, which usually persist throughout life, always require therapeutic intervention if they start to cause clinical symptoms. Based on individual parameters (such as diameter, location and growth dynamics), different treatments, including cryotherapy, corticosteroids, laser therapy, sclerotherapy, surgery, and/or embolization, can be performed successfully. Currently, however, none of these treatments represents the solitary treatment of choice.

  3. Vascular calcification: Inducers and inhibitors

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Donghyun, E-mail: dhlee@cau.ac.kr [Department of Biomedical Engineering, Division of Integrative Engineering, Chung-Ang University, 221 Heukseok-Dong, Dongjak-Gu, Seoul 156-756 (Korea, Republic of)

    2011-09-15

    Highlights: {center_dot} Types of vascular calcification processes. {center_dot} Inducers of vascular calcification. {center_dot} Inhibitors of vascular calcifications. {center_dot} Clinical utility for vascular calcification therapy. {center_dot} Implications for the development of new tissue engineering strategies. - Abstract: Unlike the traditional beliefs, there are mounting evidences suggesting that ectopic mineral depositions, including vascular calcification are mostly active processes, many times resembling that of the bone mineralization. Numbers of agents are involved in the differentiation of certain subpopulation of smooth muscle cells (SMCs) into the osteoblast-like entity, and the activation and initiation of extracellular matrix ossification process. On the other hand, there are factors as well, that prevent such differentiation and ectopic calcium phosphate formation. In normal physiological environments, activities of such procalcific and anticalcific regulatory factors are in harmony, prohibiting abnormal calcification from occurring. However, in certain pathophysiological conditions, such as atherosclerosis, chronic kidney disease (CKD), and diabetes, such balances are altered, resulting in abnormal ectopic mineral deposition. Understanding the factors that regulate the formation and inhibition of ectopic mineral formation would be beneficial in the development of tissue engineering strategies for prevention and/or treatment of such soft-tissue calcification. Current review focuses on the factors that seem to be clinically relevant and/or could be useful in developing future tissue regeneration strategies. Clinical utilities and implications of such factors are also discussed.

  4. Trauma vascular, visión del cirujano vascular

    OpenAIRE

    Dr. D. Cristián Salas

    2011-01-01

    El 3% de todas las lesiones en trauma tiene un componente vascular. Con los conflictos armados del siglo pasado se lograron grandes avances en este campo. A partir de la Guerra de Vietnam gracias a las mejoras en el manejo prehospitalario, traslado de pacientes, y avances en técnica quirúrgica se lograron tasas de sobrevida y de amputaciones que se han mantenido estables hasta la fecha. El diagnóstico de lesiones vasculares en extremidades se realiza con el examen físico, sin embargo las lesi...

  5. Complexities within the shallow conduit during Vulcanian explosions: Insights from Episode IV of the 1912 eruption of Novarupta, Alaska

    Science.gov (United States)

    Weaver, S. J.; Houghton, B. F.; Gonnermann, H. M.; Arbaret, L.; Burgisser, A.

    2015-12-01

    Models for initiation of Vulcanian eruptions involve disruption of a conduit-sealing plug or dome and the downward propagation of decompression and fragmentation waves into the conduit. At this time, we have a limited understanding of the physical state of the magma prior to its disruption, including the range of viscosities and vesicularities and the extent to which brecciated, outgassed, degassed, and volatile-rich melt may be co-mingled. Current models propose that the dense, outgassed dome/plug overlies an orderly, predominantly horizontally layered conduit with pressure increasing with depth. The 1912 eruption of Novarupta, Alaska, U.S.A. provided a unique situation to study Vulcanian explosions because its proximal deposits are exceptionally well preserved. After 60 hours and three episodes of Plinian activity and caldera collapse 10 km from vent, a dacite dome was extruded and completely destroyed by a Vulcanian phase. The fifth and final episode comprised of extrusion of a rhyolite dome without explosive activity, thus allowing preservation of the Episode IV Vulcanian block apron. We have collected data on over 1,300 of the largest juvenile and lithic blocks within an ~2-3 km radius from vent, making Episode IV the best mapped Vulcanian deposit in the world to-date. Sectors rich in specific lithologies (pumice, dense dacite, flow-banded clasts or breccia, +/- breadcrusting) and/or of contrasting block size suggest multiple explosions. Vesicularities of breadcrust rinds preserve syn-eruptive vesicularities and volatile contents and suggest considerable heterogeneity on length scales down to mm. Their vesicularity range is between 0.5 and 55% whereas dense dacite blocks lie between 0 and 33%. On equally short length scales, similar broad ranges for porosity/permeability and contrasts in micro-textures indicate major physical and chemical heterogeneity reflecting very local variations in the extent to which the melt was degassed or outgassed. Our new data

  6. Relationship between upper and lower limb conduit artery vasodilator function in humans.

    Science.gov (United States)

    Thijssen, Dick H J; Rowley, Nicola; Padilla, Jaume; Simmons, Grant H; Laughlin, M Harold; Whyte, Greg; Cable, N Timothy; Green, Daniel J

    2011-07-01

    Brachial artery flow-mediated dilation (FMD) is a strong predictor of future cardiovascular disease and is believed to represent a "barometer" of systemic endothelial health. Although a recent study [Padilla et al. Exp Biol Med (Maywood) 235: 1287-1291, 2010] in pigs confirmed a strong correlation between brachial and femoral artery endothelial function, it is unclear to what extent brachial artery FMD represents a systemic index of endothelial function in humans. We conducted a retrospective analysis of data from our laboratory to evaluate relationships between the upper (i.e., brachial artery) vs. lower limb (superficial femoral n = 75; popliteal artery n = 32) endothelium-dependent FMD and endothelium-independent glyceryl trinitrate (GTN)-mediated dilation in young, healthy individuals. We also examined the relationship between FMD assessed in both brachial arteries (n = 42). There was no correlation between brachial and superficial femoral artery FMD (r(2) = 0.008; P = 0.46) or between brachial and popliteal artery FMD (r(2) = 0.003; P = 0.78). However, a correlation was observed in FMD between both brachial arteries (r(2) = 0.34; P < 0.001). Brachial and superficial femoral artery GTN were modestly correlated (r(2) = 0.13; P = 0.007), but brachial and popliteal artery GTN responses were not (r(2) = 0.08; P = 0.11). Collectively, these data indicate that conduit artery vasodilator function in the upper limbs (of healthy humans) is not predictive of that in the lower limbs, whereas measurement of FMD in one arm appears to be predictive of FMD in the other. These data do not support the hypothesis that brachial artery FMD in healthy humans represents a systemic index of endothelial function.

  7. Dynamics of Bubbly-magma Flow in Conduits: Stress and Expansion Regimes of Magma Fragmentation

    Science.gov (United States)

    Mitani, N. K.; Koyaguchi, T.; Ida, Y.

    2002-12-01

    Explosive volcanic eruptions are characterized by magma fragmentation, that is, the process through which a bubbly magma is changed into a gas-pyroclast dispersion. Two criteria of mechanisms have been proposed for the magma fragmentation so far. First, magma fragments when stress or strain rate of magma around bubbles exceeds a critical value. Second, magma disrupts due to the instability of thin magma-foam. Which criterion is actually applicable is not yet known. In order to clarify the physics of the magma fragmentation, we numerically study one-dimensional steady flows with bubble growth in conduits. The spherical cell model is used to calculate expansion of bubbles in ascending visco-elastic magma. The stress around bubbles generally grows as magma ascends and the pressure difference between bubbles and surrounding magma increases. In some conditions, the stress becomes critically large only when the flow velocity approaches the sound speed meeting the choking condition. In other conditions, the stress becomes large enough as magma pressure drops with bubble pressure kept almost unchanged. These two distinct types may correspond to the above two criteria of fragmentation mechanisms. In the former case, void fraction becomes close to unity before the stress reaches the strength of magma. In such case, the magma does not fragment due to the visco-elastic deformations but fragments by the instability of the thin magma-foam (`expansion' regime). In the latter case, on the other hand, the stress reaches the magma strength at much lower void fractions. In such case, the magma fragments due to the visco-elastic deformation around bubbles (`stress' regime). The `expansion' and `stress' regimes occur when the ratio of the initial wall-friction stress to the magma strength is sufficiently smaller and greater than unity, respectively.

  8. Formation and Maintenance of a Viscous Plug in a Strombolian Volcanic Conduit

    Science.gov (United States)

    Llewellin, E. W.; Jones, T. J.; Jenkins, A. P.

    2015-12-01

    Textural studies of pyroclasts have shown that both degassed, crystal-rich magma, and gas-rich, crystal-poor magma may be ejected by a single strombolian explosion. Furthermore, some pyroclasts contain both magma types, intermingled. These pyroclasts have been interpreted as evidence of the presence of a plug of degassed, crystal-rich - and therefore high-viscosity - magma at the top of the volcanic conduit, overlying gas-rich, crystal-poor, low-viscosity magma. Analogue experiments have indicated that the presence of a viscous plug increases the vigour of strombolian explosions by enhancing the build-up of overpressure in the gas slug that drives them. The purported plug material has a higher density, as well as a higher viscosity, than the magma that underlies it. Consequently, the configuration is expected to be unstable, and the plug and underlying magma should convectively overturn. Does this mean that a viscous plug is an ephemeral feature? Or can a plug persist for long periods as a dynamic feature, which is continually created at the same rate at which it is convectively consumed? We conduct laboratory analogue experiments to investigate the formation and maintenance of a viscous plug. We drive thermal convection of a range of Newtonian and non-Newtonian magma analogue fluids in a 20cm diameter vertical pipe by heating the bottom, and cooling the top. The fluids have strongly temperature dependent rheology; both rheology and driving buoyancy are scaled to the volcanic scenario. We present preliminary results which characterize the spatial distribution of viscosity, density and velocity. We find that the hotter, lower-viscosity fluid ascends the core of the pipe, whilst the cooler, higher-viscosity fluid descends in an outer annulus. The upper region, in which the flow reverses direction, constitutes a dynamic plug.

  9. Time scales of foam stability in shallow conduits: Insights from analogue experiments

    Science.gov (United States)

    Spina, L.; Scheu, B.; Cimarelli, C.; Arciniega-Ceballos, A.; Dingwell, D. B.

    2016-10-01

    Volcanic systems can exhibit periodical trends in degassing activity, characterized by a wide range of time scales. Understanding the dynamics that control such periodic behavior can provide a picture of the processes occurring in the feeding system. Toward this end, we analyzed the periodicity of outgassing in a series of decompression experiments performed on analogue material (argon-saturated silicone oil plus glass beads/fibers) scaled to serve as models of basaltic magma. To define the effects of liquid viscosity and crystal content on the time scale of outgassing, we investigated both: (1) pure liquid systems, at differing viscosities (100 and 1000 Pa s), and (2) particle-bearing suspensions (diluted and semidiluted). The results indicate that under dynamic conditions (e.g., decompressive bubble growth and fluid ascent within the conduit), the periodicity of foam disruption may be up to several orders of magnitude less than estimates based on the analysis of static conditions. This difference in foam disruption time scale is inferred to result from the contribution of bubble shear and bubble growth to inter-bubble film thinning. The presence of particles in the semidiluted regime is further linked to shorter bubble bursting times, likely resulting from contributions of the presence of a solid network and coalescence processes to the relative increase in bubble breakup rates. Finally, it is argued that these experiments represent a good analogue of gas-piston activity (i.e., the periodical rise-and-fall of a basaltic lava lake surface), implying a dominant role for shallow foam accumulation as a source process for these phenomena.

  10. Jointing around Magmatic Dikes as a Precursor to Conduit Geometry Evolution

    Science.gov (United States)

    Townsend, M.; Culha, C.; Johnson, K.; Pollard, D. D.

    2014-12-01

    Basaltic volcanic eruptions commonly follow a characteristic sequence of events. In the upper few kilometers of the crust, magma rises in planar dikes, which result in fissure eruptions when they intersect the surface. In some cases, the fissures do not feed significant eruptions and die out within hours. In other cases, magma stops flowing in much of the fissure, but continues to erupt from discrete vents, until finally the flow is sustained through a single vent underlain by a volcanic plug that is able to carry much greater volumes of magma to the surface. Ancient volcanic systems that have been exposed by erosion provide a unique opportunity to directly investigate a volcanic plumbing system and gain insight on the physical mechanisms responsible for conduit geometry evolution. Here we present field data from an Oligocene-aged dike-plug system at Ship Rock, New Mexico, collected from a DEM and overlaying orthophotograph made using new techniques from structure from motion. We document and characterize a systematic set of over 200 dike-perpendicular joints found in the sedimentary host rock adjacent to the intrusions. This joint set, along with a set of dike-parallel joints and the bedding planes in the host rock, allows the host rock to be broken into individual blocks that can be subsequently entrained in the flowing magma to widen the dike. We use elastic crack models and solutions for coupled heat and fluid flow in porous media to understand the conditions necessary for host-rock fracturing to occur. We show that this fracturing is intimately associated with the interaction of magma and groundwater and is a precursor to erosion of the host rock and sustained flow through discrete vents.

  11. An Ongoing Role of α-Calcitonin Gene–Related Peptide as Part of a Protective Network Against Hypertension, Vascular Hypertrophy, and Oxidative Stress

    DEFF Research Database (Denmark)

    Smillie, Sarah-Jane; King, Ross; Kodji, Xenia

    2014-01-01

    at the vascular level. Wild-type and αCGRP knockout mice that have similar baseline blood pressure were investigated in the angiotensin II hypertension model for 14 and 28 days. αCGRP knockout mice exhibited enhanced hypertension and aortic hypertrophy. αCGRP gene expression was increased in dorsal root ganglia...... and at the conduit and resistance vessel level of wild-type mice at both time points. βCGRP gene expression was also observed and shown to be linked to plasma levels of CGRP. Mesenteric artery contractile and relaxant responses in vitro and endothelial NO synthase expression were similar in all groups. The aorta...

  12. Heritability of Retinal Vascular Fractals

    DEFF Research Database (Denmark)

    Vergmann, Anna Stage; Broe, Rebecca; Kessel, Line

    2017-01-01

    , the branching pattern of the retinal vessels demonstrated a higher structural similarity in monozygotic than in dizygotic twin pairs. The retinal vascular fractal dimension was mainly determined by genetic factors, which accounted for 54% of the variation. The genetically predetermination of the retinal......Purpose: To determine the genetic contribution to the pattern of retinal vascular branching expressed by its fractal dimension. Methods: This was a cross-sectional study of 50 monozygotic and 49 dizygotic, same-sex twin pairs aged 20 to 46 years. In 50°, disc-centered fundus photographs......, the retinal vascular fractal dimension was measured using the box-counting method and compared within monozygotic and dizygotic twin pairs using Pearson correlation coefficients. Falconer's formula and quantitative genetic models were used to determine the genetic component of variation. Results: The mean...

  13. Fetal origin of vascular aging

    Directory of Open Access Journals (Sweden)

    Shailesh Pitale

    2011-01-01

    Full Text Available Aging is increasingly regarded as an independent risk factor for development of cardiovascular diseases such as atherosclerosis and hypertension and their complications (e.g. MI and Stroke. It is well known that vascular disease evolve over decades with progressive accumulation of cellular and extracellular materials and many inflammatory processes. Metabolic syndrome, obesity and diabetes are conventionally recognized as risk factors for development of coronary vascular disease (CVD. These conditions are known to accelerate ageing process in general and vascular ageing in particular. Adverse events during intrauterine life may programme organ growth and favour disease later in life, popularly known as, ′Barker′s Hypothesis′. The notion of fetal programming implies that during critical periods of prenatal growth, changes in the hormonal and nutritional milieu of the conceptus may alter the full expression of the fetal genome, leading to permanent effects on a range of physiological.

  14. [Alzheimer's disease and vascular dementia].

    Science.gov (United States)

    Nagata, Ken

    2014-04-01

    Alzheimer's disease (AD) and vascular dementia (VaD) are the two major forms of dementia in the elderly, and they had been separated categorically on the basis of pathogenetic mechanisms and clinical operationalized criteria. However, it was claimed that this strict separation might steered toward the overdiagnosis of vascular dementia, this dichotomy has been reevaluated in the light of recent epidemiological and neuropathological knowledge. Cerebrovascular disease (CVD) is now considered as one of the vascular risk factors to the onset and evolution of Alzheimer's disease. Futhermore, the term "AD with CVD" has been used to classify patients fulfilling the clinical criteria for possible AD and who also present clinical or brain imaging evidence of relevant CVD.

  15. Vascular education and training in Asia.

    Science.gov (United States)

    Jirasiritham, Sopon

    2008-12-01

    Cardiovascular diseases have become more prevalent and threatening to the health of the population of Asia due to the rapidly growing number of aging people. The Asian Society for Vascular Surgery unites 13 member organizations: Japan, Korea, China, India, Hong Kong, Singapore, Malaysia, Taiwan, Bangladesh, Philippines, Saudi Arabia, Indonesia, and Thailand. The essential mission of the Asian Society for Vascular Surgery is to improve training in vascular surgery to increase the number of competent vascular surgeons in Asia. Almost every member country has its own vascular training program. Most curricula for vascular surgery training are composed of basic vascular research, clinical vascular medicine, vascular investigation, and open and endovascular surgery, with the period of training ranging from 2 to 4 years.

  16. Five-year results of a merger between vascular surgeons and interventional radiologists in a university medical center.

    Science.gov (United States)

    Green, Richard M; Waldman, David

    2003-12-01

    We examined economic and practice trends after 5 years of a merger between vascular surgeons and interventional radiologists. In 1998 a merger between the Division of Vascular Surgery and the Section of Interventional Radiology at the University of Rochester established the Center for Vascular Disease (CVD). Business activity was administered from the offices of the vascular surgeons. In 1998 the CVD included five vascular surgeons and three interventional radiologists, who generated a total income of $5,789,311 US dollars (34% from vascular surgeons, 24% from interventional radiologists, 42% from vascular laboratories). Vascular surgeon participation in endoluminal therapy was limited to repair of abdominal aortic aneurysms (AAAs). Income was derived from 1011 major vascular procedures, 10,510 catheter-based procedures in 3286 patients, and 1 inpatient and 3 outpatient vascular laboratory tests. In 2002 there were six vascular surgeons (five, full-time equivalent) and four interventional radiologists, and total income was $6,550,463 US dollars despite significant reductions in unit value reimbursement over the 5 years, a 4% reduction in the number of major vascular procedures, and a 13% reduction in income from vascular laboratories. In 2002 the number of endoluminal procedures increased to 16,026 in 7131 patients, and contributions to CVD income increased from 24% in 1998 to 31% in 2002. Three of the six vascular surgeons performed endoluminal procedures in 634 patients in 2002, compared with none in 1998. Gross revenues increased in a declining reimbursement and conventional practice environment, because of the increased number of endoluminal procedures, in part provided by vascular surgeons. The implications of these data should be considered by those responsible for training vascular surgeons.

  17. Cardio-ankle vascular index (CAVI) differentiates pharmacological properties of vasodilators nicardipine and nitroglycerin in anesthetized rabbits.

    Science.gov (United States)

    Chiba, Tatsuo; Yamanaka, Mari; Takagi, Sachie; Shimizu, Kazuhiro; Takahashi, Mao; Shirai, Kohji; Takahara, Akira

    2015-08-01

    Cardio-ankle vascular index (CAVI) has been developed for measurement of vascular stiffness from the aorta to tibial artery, which is clinically utilized for assessing the progress of arteriosclerosis. In this study, we established measuring system of the CAVI in rabbits, and assessed whether the index could reflect different pharmacological actions of nitroglycerin and nicardipine on the systemic vasculature. Rabbits were anesthetized with halothane, and the CAVI was calculated from the well-established basic equations with variables obtained from brachial and tibial blood pressure and phonocardiogram. Nicardipine (1, 3 and 10 μg/kg, i.v.) decreased the blood pressure, femoral vascular resistance, and heart-ankle pulse wave velocity (haPWV). Meanwhile, no significant change was detected in the CAVI at the low or middle dose, which reflects the defining feature of the CAVI that is independent of blood pressure. The index increased at the high dose. Nitroglycerin (2, 4 and 8 μg/kg, i.v.) decreased the blood pressure, femoral vascular resistance, and haPWV. Meanwhile, the CAVI was decreased during the nitroglycerin infusion, which may reflect its well-known pharmacological action dilating conduit arteries. These results suggest that the CAVI differentiates the properties of these vasodilators in vivo. Copyright © 2015 The Authors. Production and hosting by Elsevier B.V. All rights reserved.

  18. Angioembolisation in vaginal vascular malformation.

    Directory of Open Access Journals (Sweden)

    Srivastava D

    2001-01-01

    Full Text Available Vaginal arteriovenous malformations are rare entities and their most common presentation is vaginal haemorrhage. This case report describes a 22-year-old woman who presented at 20 weeks of gestation with slow growing soft and tender swelling at anterior vaginal wall. Diagnosis was confirmed as vaginal vascular malformation on contrast enhanced magnetic resonance imaging. The mass did not subside after delivery and patient developed dyspareunia. It was successfully treated by angioembolisation using polyvinyl alcohol particles. Angioembolisation being safe and effective should be the treatment of first choice for symptomatic vaginal vascular malformation.

  19. Self-Replenishing Vascularized Fouling-Release Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Howell, C; Vu, TL; Lin, JJ; Kolle, S; Juthani, N; Watson, E; Weaver, JC; Alvarenga, J; Aizenberg, J

    2014-08-13

    Inspired by the long-term effectiveness of living antifouling materials, we have developed a method for the self-replenishment of synthetic biofouling-release surfaces. These surfaces are created by either molding or directly embedding 3D vascular systems into polydimethylsiloxane (PDMS) and filling them with a silicone oil to generate a nontoxic oil-infused material. When replenished with silicone oil from an outside source, these materials are capable of self-lubrication and continuous renewal of the interfacial fouling-release layer. Under accelerated lubricant loss conditions, fully infused vascularized samples retained significantly more lubricant than equivalent nonvascularized controls. Tests of lubricant-infused PDMS in static cultures of the infectious bacteria Staphylococcus aureus and Escherichia coli as well as the green microalgae Botryococcus braunii, Chlamydomonas reinhardtii, Dunaliella sauna, and Nannochloropsis oculata showed a significant reduction in biofilm adhesion compared to PDMS and glass controls containing no lubricant. Further experiments on vascularized versus nonvascularized samples that had been subjected to accelerated lubricant evaporation conditions for up to 48 h showed significantly less biofilm adherence on the vascularized surfaces. These results demonstrate the ability of an embedded lubricant-filled vascular network to improve the longevity of fouling-release surfaces.

  20. Exposure to Diesel Exhaust Enhances the Generation of Vascular Microparticles

    Science.gov (United States)

    Introduction: In the study of the health impacts of traffic-related air pollution, diesel exhaust is a pollutant of particular interest, since it is a major source of particulate matter (PM). Epidemiological studies associate exposure to ambient levels of PM with cardiovascular m...

  1. Exposure to Air Pollution Enhances the Generation of Vascular Microparticles

    Science.gov (United States)

    Epidemiological studies associate exposure to ambient levels of particulate matter (PM) with cardiovascular morbidity and mortality. The biological mechanisms by which PM exposure induces cardiovascular effects remain to be elucidated. One important limitation is the lack of sens...

  2. Reactive oxygen species and angiotensin II signaling in vascular cells: implications in cardiovascular disease

    Directory of Open Access Journals (Sweden)

    Touyz R.M.

    2004-01-01

    Full Text Available Diseases such as hypertension, atherosclerosis, hyperlipidemia, and diabetes are associated with vascular functional and structural changes including endothelial dysfunction, altered contractility and vascular remodeling. Cellular events underlying these processes involve changes in vascular smooth muscle cell (VSMC growth, apoptosis/anoikis, cell migration, inflammation, and fibrosis. Many factors influence cellular changes, of which angiotensin II (Ang II appears to be amongst the most important. The physiological and pathophysiological actions of Ang II are mediated primarily via the Ang II type 1 receptor. Growing evidence indicates that Ang II induces its pleiotropic vascular effects through NADPH-driven generation of reactive oxygen species (ROS. ROS function as important intracellular and intercellular second messengers to modulate many downstream signaling molecules, such as protein tyrosine phosphatases, protein tyrosine kinases, transcription factors, mitogen-activated protein kinases, and ion channels. Induction of these signaling cascades leads to VSMC growth and migration, regulation of endothelial function, expression of pro-inflammatory mediators, and modification of extracellular matrix. In addition, ROS increase intracellular free Ca2+ concentration ([Ca2+]i, a major determinant of vascular reactivity. ROS influence signaling molecules by altering the intracellular redox state and by oxidative modification of proteins. In physiological conditions, these events play an important role in maintaining vascular function and integrity. Under pathological conditions ROS contribute to vascular dysfunction and remodeling through oxidative damage. The present review focuses on the biology of ROS in Ang II signaling in vascular cells and discusses how oxidative stress contributes to vascular damage in cardiovascular disease.

  3. Vascular ultrasound for atherosclerosis imaging

    NARCIS (Netherlands)

    C.L. de Korte (Chris); H.H.G. Hansen (Hendrik); A.F.W. van der Steen (Ton)

    2011-01-01

    textabstractCardiovascular disease is a leading cause of death in the Western world. Therefore, detection and quantification of atherosclerotic disease is of paramount importance to monitor treatment and possible prevention of acute events. Vascular ultrasound is an excellent technique to assess the

  4. Signaling circuitry in vascular morphogenesis.

    Science.gov (United States)

    Warren, Carmen M; Iruela-Arispe, M Luisa

    2010-05-01

    In this mini-review, we have highlighted the recent breakthroughs in growth factor signaling that have made conceptual changes in our understanding of how blood vessels are formed. Studies conducted over the past few years have focused on understanding the cell biology of vascular morphogenesis. The major themes include characterization of the different cell types that comprise a vascular sprout, as well as the regulatory influence of cell-cell and cell-matrix interactions on signaling outcomes. In addition, novel trends have emerged, including nonconventional ways in which vascular endothelial growth factor contributes to cell survival and metabolic balance. The growth of new capillary sprouts from a preexisting vascular network requires a highly coordinated cellular response to both growth factors and morphogens. This response is sensed and triggered by cell surface receptors responsible for the activation of an intracellular cascade that efficiently initiates migration and proliferation programs. While the molecular players that coordinate these effects have been identified, recent findings have expanded our understanding of how context, in particular cell-cell and cell-matrix interactions, affects endothelial cell responses to growth factors.

  5. Vascular complications in orthopedic surgery.

    Science.gov (United States)

    Chervu, A; Quinones-Baldrich, W J

    1988-10-01

    Vascular complications may be seen secondary to trauma or in the perioperative period following elective surgery. Prompt recognition and correction of these problems are of utmost importance to assure functional viability of the affected extremity. Evaluation may be complicated by the presence of preexisting atherosclerotic occlusive disease in the elderly patient. Relevant points in the history and physical examination include mechanism of injury, preexisting disease, evaluation of motor and sensory function, and presence and character of pulses. Noninvasive vascular studies should be obtained in all patients. Absolute indications for angiography include absent pulses, signs and symptoms of ischemia, a bruit, and a posterior knee dislocation; decreased pulses, a significant hematoma, and proximity of the fracture fragment are relative indications. Controversial issues in the management of combined orthopedic and vascular injuries include the use of internal versus external fixation, the use of prosthetic versus autogenous material, and the need for venous reconstruction. Popliteal artery trauma is still associated with a high limb loss rate, and careful evaluation of knee injuries is necessary. Vascular compromise may also complicate joint replacement surgery. These complications are preventable, and management is greatly simplified by a detailed preoperative evaluation.

  6. Intestinal vascular anomalies in children.

    Science.gov (United States)

    Frémond, B; Yazbeck, S; Dubois, J; Brochu, P; Garel, L; Ouimet, A

    1997-06-01

    Vascular anomalies are an uncommon cause of gastrointestinal bleeding in childhood. Confusing nomenclature has made objective comparisons of published cases difficult and has interfered with an established consensus regarding diagnosis and therapeutic modalities. The purpose of this study was to clarify the situation by reviewing the records of all children who had intestinal vascular anomalies who were referred to our institution from 1975 to 1995. Thirteen lesions were identified in nine children (five boys and four girls). The median age at clinical onset was 8 years. Only two patients presented with a complex syndrome (Klippel-Trenaunay, 1; Osler-Rendu-Weber, 1). Diagnosis, location, and extension of these anomalies was only possible by angiography, which indicated that seven patients had isolated venous malformations and two had arteriovenous malformations. Because the lesions did not involve the serosa, intraoperative localization was a major problem. The main findings were a few slightly dilated mesenteric veins. Treatment was conservative in four children and surgical in five. Pathological findings on resected bowel demonstrated dilated and abnormal veins in the mucosa and submucosa. Selective angiography should not be delayed in patients with gastrointestinal bleeding if results of all other investigations are negative. Because these lesions are rarely recognizable on operative inspection, precise preoperative angiographic localization of intestinal vascular anomalies is essential to allow for a safe and limited resection of the involved bowel segment. Based on a better understanding of the natural history of these lesions, a classification of vascular anomalies of intestines in children is proposed.

  7. Silk Biomaterials with Vascularization Capacity.

    Science.gov (United States)

    Han, Hongyan; Ning, Hongyan; Liu, Shanshan; Lu, Qiang; Fan, Zhihai; Lu, Haijun; Lu, Guozhong; Kaplan, David L

    2016-01-20

    Functional vascularization is critical for the clinical regeneration of complex tissues such as kidney, liver or bone. The immobilization or delivery of growth factors has been explored to improve vascularization capacity of tissue engineered constructs, however, the use of growth factors has inherent problems such as the loss of signaling capability and the risk of complications such as immunological responses and cancer. Here, a new method of preparing water-insoluble silk protein scaffolds with vascularization capacity using an all aqueous process is reported. Acid was added temporally to tune the self-assembly of silk in lyophilization process, resulting in water insoluble scaffold formation directly. These biomaterials are mainly noncrystalline, offering improved cell proliferation than previously reported silk materials. These systems also have appropriate softer mechanical property that could provide physical cues to promote cell differentiation into endothelial cells, and enhance neovascularization and tissue ingrowth in vivo without the addition of growth factors. Therefore, silk-based degradable scaffolds represent an exciting biomaterial option, with vascularization capacity for soft tissue engineering and regenerative medicine.

  8. Chemistry, mineralogy and alteration intensity of hydrothermal altered Mt Unzen conduit rocks (Shimabara/Japan)

    Science.gov (United States)

    Hess, Kai-Uwe; Yilmaz, Tim; Gilg, H. Albert; Janots, Emilie; Mayer, Klaus; Nakada, Setsuya; Dingwell, Donald

    2017-04-01

    Investigations were carried out on hydrothermally altered coherent dacitic dykes samples from (USDP-4) drill core at Mt Unzen stratovolcano (Shimabara/Japan). XRF, XRD, EMPA, C-O-isotope, hot-cathode CL and SEM analysis led to insights concerning chemistry, mineralogy, and intensity and type of alteration as well as the origin of carbonate-precipitating fluids. Additionally a textural characterization of the occurring replacement features in the volcanic conduit rocks was performed. The occurrence of the main secondary phases such as chlorite, pyrite, carbonates, and R1 (Reichweite parameter) illite-smectite and kaolinite group minerals indicate a weak to moderate propylitic to phyllic hydrothermal alteration. The dacitic samples of the dykes show different hydrothermal alteration features: (i) carbonate and chlorite pseudomorphs after hornblende as well as core and zonal textures due to replacement of plagioclase by R1 illite-smectite as well as kaolinite group minerals, (ii) colloform banded fracture fillings and fillings in dissolution vugs, and (iii) chlorite, R1 illite-smectite as well as kaolinite group minerals in the groundmass. Late chlorite veins crosscut precipitates of R1 illite-smectite as well as kaolinite group minerals. Carbonates in fractures and in pseudomorphs after hornblende comprise iron-rich dolomite solid solutions ("ankerite") and calcite. Isotopic values indicate a hydrothermal-magmatic origin for the carbonate formation. The chlorite-carbonate-pyrite index (CCPI) and the Ishikawa alteration index (AI), applied to the investigated samples show significant differences (CCPI=52.7-57.8; AI=36.1-40.6) indicating their different degree of alteration. According to Nakada et al., 2005, the C13 to C16 dykes represent the feeder dyke from the latest eruption (1991-1995) whereas C8 represents an earlier dyke feeder dyke from an older eruption. Weakest alteration, which was obtained in samples C16-1-5 and C13-2-5, correlates with the alteration

  9. Clean Sampling of an Englacial Conduit at Blood Falls, Antarctica - Some Experimental and Numerical Results

    Science.gov (United States)

    Kowalski, Julia; Francke, Gero; Feldmann, Marco; Espe, Clemens; Heinen, Dirk; Digel, Ilya; Clemens, Joachim; Schüller, Kai; Mikucki, Jill; Tulaczyk, Slawek M.; Pettit, Erin; Berry Lyons, W.; Dachwald, Bernd

    2017-04-01

    results of its deployment at Blood Falls. In contrast to conventional melting-probe applications, which can only melt vertically, the IceMole realized an oblique melting path to penetrate the englacial conduit. Experimental and numerical results on melting at oblique angles are rare. Besides reporting on the IceMole technology and the field deployment itself, we will compare and discuss the observed melting behavior with re-analysis results in the context of a recently developed numerical model. Finally, we will present our first steps in utilizing the model to infer on the ambient cryo-environment.

  10. Brilliant Blue FCF as an Alternative Dye for Saphenous Vein Graft Marking Effect on Conduit Function

    Science.gov (United States)

    Voskresensky, Igor V.; Wise, Eric S.; Hocking, Kyle M.; Li, Fan Dong; Osgood, Michael J.; Komalavilas, Padmini; Brophy, Colleen; Cheung-Flynn, Joyce

    2014-01-01

    −27.9% [3.7%] for HSVs after manipulation; P dye that may improve HSV conduit function and decrease intimal hyperplasia. PMID:25251505

  11. Markers of Early Vascular Ageing.

    Science.gov (United States)

    Kotsis, Vasilios; Antza, Christina; Doundoulakis, Ioannis; Stabouli, Stella

    2017-01-01

    Cardiovascular damage is clinically manifested as coronary artery disease, heart failure, stroke and peripheral artery disease. The prevalence of these adverse conditions is higher with advancing age. Although many patients present cardiovascular damage late in their life, it is common to see patients with early atherosclerosis in cardiovascular intensive care units at ages lower than 50 years in men and 55 for women. In this review of the literature we identified risk factors of early vascular damage. The classic risk factors such as age, gender, diabetes mellitus, dyslipidemia, smoking, alcohol, hypertension, obesity, family history and newer biomarkers such as hs-CRP, folic acid, homocysteine, fibrinogen are neither strong nor predictive of the individual patient's risk to present early cardiovascular disease. All these risk factors have been used to propose risk scores for possible future events but we still lack a single strong marker indicating new onset of disease that will predict the future independently of the classical factors. The role of vascular imaging techniques to identify patients with subclinical atherosclerotic vascular damage before clinical disease, including the effect of known and unknown risk factors on the vascular tree, seems to be very important for intensifying preventive measures in high risk patients. Early arteriosclerosis measured from pulse wave velocity is associated with reduced arterial elasticity and is associated with future cardiovascular events. Vascular measurements may better represent the continuum of cardiovascular disease from a young healthy to an aged diseased vessel that is going to produce adverse clinical events. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  12. Origin of karst conduits in calcareous sandstone and carbonate-silicate rocks: Complex role of insoluble material

    Science.gov (United States)

    Bruthans, Jiri; Balak, Frantisek; Schweigstillova, Jana; Vojtisek, Jan

    2017-04-01

    Carbonate karst is best developed in high-grade limestones and majority of the studies is focused on these rocks. Features developed by dissolution of calcite cement in quartz sandstones and dissolution of various carbonate-silicate rocks are studied far less frequently. Unlike in common karst, the insoluble residuum has to be washed out after dissolution to create high-permeability conduits in these rocks. Aquifers in a Bohemian Cretaceous Basin (BCB), the most important hydrogeological basin in the Czech Republic, consist mainly of quartz and calcareous sandstones to siltstones. These rocks are intercalated by thin layers of calcite-cemented sandstone and low-grade limestone, the latter sometimes partly impregnated by a secondary silica. Results of tracer tests show a high flow velocity in some of the aquifers. Springs with flow rate up to 500 l/s and wells with yield up to 200 l/s occur in these rocks. Dissolution features in BCB were however not yet studied in detail. For identification and characterization of rocks prone to karstification, 350 cores were sampled mostly from boreholes but also from rock outcrops in several areas of BCB. Cores were taken from intervals where: (i) high carbonate content was expected, (ii) conduits and enlarged porosity was observed in rock outcrops or wells, (iii) inflows to boreholes were determined by well logging. Calcium carbonate content was determined by calcimetry in all cores. All cores were leached in hydrochloric acid to observe the degree of disintegration after removal of calcite, which was far dominating portion of total carbonate. Polished sections were prepared from selected cores and Ca, Si, Na, K, Al content was automatically mapped by microprobe to visualize the calcium, silica, feldspar and clay mineral distribution in cores. Conduits were photo documented in the field. Two types of sediments with distinct disintegration characteristics were observed: (i) In sandstone composed of quartz grains cemented by

  13. Characterization and Schwann Cell Seeding of up to 15.0 cm Long Spider Silk Nerve Conduits for Reconstruction of Peripheral Nerve Defects

    Directory of Open Access Journals (Sweden)

    Tim Kornfeld

    2016-11-01

    Full Text Available Nerve reconstruction of extended nerve defect injuries still remains challenging with respect to therapeutic options. The gold standard in nerve surgery is the autologous nerve graft. Due to the limitation of adequate donor nerves, surgical alternatives are needed. Nerve grafts made out of either natural or artificial materials represent this alternative. Several biomaterials are being explored and preclinical and clinical applications are ongoing. Unfortunately, nerve conduits with successful enhancement of axonal regeneration for nerve defects measuring over 4.0 cm are sparse and no conduits are available for nerve defects extending to 10.0 cm. In this study, spider silk nerve conduits seeded with Schwann cells were investigated for in vitro regeneration on defects measuring 4.0 cm, 10.0 cm and 15.0 cm in length. Schwann cells (SCs were isolated, cultured and purified. Cell purity was determined by immunofluorescence. Nerve grafts were constructed out of spider silk from Nephila edulis and decellularized ovine vessels. Finally, spider silk implants were seeded with purified Schwann cells. Cell attachment was observed within the first hour. After 7 and 21 days of culture, immunofluorescence for viability and determination of Schwann cell proliferation and migration throughout the conduits was performed. Analyses revealed that SCs maintained viable (>95% throughout the conduits independent of construct length. SC proliferation on the spider silk was determined from day 7 to day 21 with a proliferation index of 49.42% arithmetically averaged over all conduits. This indicates that spider silk nerve conduits represent a favorable environment for SC attachment, proliferation and distribution over a distance of least 15.0 cm in vitro. Thus spider silk nerve implants are a highly adequate biomaterial for nerve reconstruction.

  14. Characterization and Schwann Cell Seeding of up to 15.0 cm Long Spider Silk Nerve Conduits for Reconstruction of Peripheral Nerve Defects

    Science.gov (United States)

    Kornfeld, Tim; Vogt, Peter M.; Bucan, Vesna; Peck, Claas-Tido; Reimers, Kerstin; Radtke, Christine

    2016-01-01

    Nerve reconstruction of extended nerve defect injuries still remains challenging with respect to therapeutic options. The gold standard in nerve surgery is the autologous nerve graft. Due to the limitation of adequate donor nerves, surgical alternatives are needed. Nerve grafts made out of either natural or artificial materials represent this alternative. Several biomaterials are being explored and preclinical and clinical applications are ongoing. Unfortunately, nerve conduits with successful enhancement of axonal regeneration for nerve defects measuring over 4.0 cm are sparse and no conduits are available for nerve defects extending to 10.0 cm. In this study, spider silk nerve conduits seeded with Schwann cells were investigated for in vitro regeneration on defects measuring 4.0 cm, 10.0 cm and 15.0 cm in length. Schwann cells (SCs) were isolated, cultured and purified. Cell purity was determined by immunofluorescence. Nerve grafts were constructed out of spider silk from Nephila edulis and decellularized ovine vessels. Finally, spider silk implants were seeded with purified Schwann cells. Cell attachment was observed within the first hour. After 7 and 21 days of culture, immunofluorescence for viability and determination of Schwann cell proliferation and migration throughout the conduits was performed. Analyses revealed that SCs maintained viable (>95%) throughout the conduits independent of construct length. SC proliferation on the spider silk was determined from day 7 to day 21 with a proliferation index of 49.42% arithmetically averaged over all conduits. This indicates that spider silk nerve conduits represent a favorable environment for SC attachment, proliferation and distribution over a distance of least 15.0 cm in vitro. Thus spider silk nerve implants are a highly adequate biomaterial for nerve reconstruction. PMID:27916868

  15. Polymerizing Pyrrole Coated Poly (l-lactic acid-co-ε-caprolactone) (PLCL) Conductive Nanofibrous Conduit Combined with Electric Stimulation for Long-Range Peripheral Nerve Regeneration.

    Science.gov (United States)

    Song, Jialin; Sun, Binbin; Liu, Shen; Chen, Wei; Zhang, Yuanzheng; Wang, Chunyang; Mo, Xiumei; Che, Junyi; Ouyang, Yuanming; Yuan, Weien; Fan, Cunyi

    2016-01-01

    Electrospinning and electric stimulation (ES) are both promising methods to support neuron adhesion and guide extension of neurons for nerve regeneration. Concurrently, all studies focus on either electrospinning for conduits material or ES in vitro study to accelerate nerve regeneration; few work on the combined use of these two strategies or ES in vivo study. Therefore, this study aimed to investigate the abilities of direct current ES through electrospinning conductive polymer composites composed of polypyrrole and Poly (l-lactic acid-co-ε-caprolactone) (PPY/PLCL) in peripheral nerve regeneration. PPY/PLCL composite conduits were synthesized by polymerizing pyrrole coated electrospun PLCL scaffolds. Morphologies and chemical compositions were characterized by scanning electron microscope and attenuated total reflection fourier transform infrared (ATR-FTIR) microscope. Rat pheochromocytoma 12 (PC12) cells and dorsal root ganglia (DRG) cells cultured on PPY/PLCL scaffolds were stimulated with 100 mV/cm for 4 h per day. The median neurite length and cell viability were measured in PC-12 cells. The levels of brain-derived neurotrophic factor (BDNF), glial cell derived neurotrophic factor (GDNF) and neurotrophin-3 (NT-3) were analyzed in DRG cells. In rats, 15 mm gaps of sciatic nerves were bridged using an autograft, non-stimulated PPY/PLCL conduit and PPY/PLCL conduit stimulated with 100 mV potential, respectively. A 100 mV potential direct current ES was applied for 1 h per day at 1, 3, 5 and 7 days post-implantation. The PPY/PLCL conduits with ES showed a similar performance compared with the autograft group, and significantly better than the non-stimulated PPY/PLCL conduit group. These promising results show that the PPY/PLCL conductive conduits' combined use with ES has great potential for peripheral nerve regeneration.

  16. Polymerizing pyrrole coated Poly (l-lactic acid-co-ε-caprolactone (PLCL conductive nanofibrous conduit combined with electric stimulation for long-range peripheral nerve regeneration

    Directory of Open Access Journals (Sweden)

    Jialin Song

    2016-11-01

    Full Text Available Electrospinning and electric stimulation (ES are both promising methods to support neurons adhesion and guide extension of neurons for nerve regeneration. Concurrently, all studies focus on either electrospinning for conduits material or ES in vitro study to accelerate nerve regeneration; few works on the combined use of these two strategies or ES in vivo study. Therefore, this study aimed to investigate the abilities of direct current ES through electrospinning conductive polymer composites composed of polypyrrole and Poly (l-lactic acid-co-ε-caprolactone (PPY/PLCL in peripheral nerve regeneration. PPY/PLCL composite conduits were synthesized by polymerizing pyrrole coated electrospun PLCL scaffolds. Morphologies and chemical compositions were characterized by scanning electron microscope and attenuated total reflection fourier transform infrared (ATR-FTIR. Rat pheochromyctoma (PC12 cells and dorsal root ganglia (DRG cells cultured on PPY/PLCL scaffolds were stimulated with 100 mV/cm for 4 h per day. The median neurite length and cell viability were measured in PC-12 cells. The levels of brain-derived neurotrophic factor (BDNF, glial cell derived neurotrophic factor (GDNF and neurotrophin-3 (NT-3 were analyzed in DRG cells. In rats, 15-mm gaps of sciatic nerves were bridged using an autograft, non-stimulated PPY/PLCL conduit and PPY/PLCL conduit stimulated with 100 mV potential, respectively. A 100 mV potential direct current ES was applied for 1h per day at 1, 3, 5, and 7 days post-implantation. The PPY/PLCL conduits with ES showed a similar performance compared with the autograft group, and significantly better than the non-stimulated PPY/PLCL conduit group. These promising results show that the PPY/PLCL conductive conduits combined use with ES has great potential for peripheral nerve regeneration.

  17. Sciatic nerve regeneration by transplantation of Schwann cells via erythropoietin controlled-releasing polylactic acid/multiwalled carbon nanotubes/gelatin nanofibrils neural guidance conduit.

    Science.gov (United States)

    Salehi, Majid; Naseri-Nosar, Mahdi; Ebrahimi-Barough, Somayeh; Nourani, Mohammdreza; Khojasteh, Arash; Hamidieh, Amir-Ali; Amani, Amir; Farzamfar, Saeed; Ai, Jafar

    2017-07-04

    The current study aimed to enhance the efficacy of peripheral nerve regeneration using an electrically conductive biodegradable porous neural guidance conduit for transplantation of allogeneic Schwann cells (SCs). The conduit was produced from polylactic acid (PLA), multiwalled carbon nanotubes (MWCNTs), and gelatin nanofibrils (GNFs) coated with the recombinant human erythropoietin-loaded chitosan nanoparticles (rhEpo-CNPs). The PLA/MWCNTs/GNFs/rhEpo-CNPs conduit had the porosity of 85.78 ± 0.70%, the contact angle of 77.65 ± 1.91° and the ultimate tensile strength and compressive modulus of 5.51 ± 0.13 MPa and 2.66 ± 0.34 MPa, respectively. The conduit showed the electrical conductivity of 0.32 S cm(-1) and lost about 11% of its weight after 60 days in normal saline. The produced conduit was able to release the rhEpo for at least 2 weeks and exhibited favorable cytocompatibility towards SCs. For functional analysis, the conduit was seeded with 1.5 × 10(4) SCs and implanted into a 10 mm sciatic nerve defect of Wistar rat. After 14 weeks, the results of sciatic functional index, hot plate latency, compound muscle action potential amplitude, weight-loss percentage of wet gastrocnemius muscle and Histopathological examination using hematoxylin-eosin and Luxol fast blue staining demonstrated that the produced conduit had comparable nerve regeneration to the autograft, as the gold standard to bridge the nerve gaps. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2017. © 2017 Wiley Periodicals, Inc.

  18. Pediatric central nervous system vascular malformations

    Energy Technology Data Exchange (ETDEWEB)

    Burch, Ezra A. [Brigham and Women' s Hospital, Department of Radiology, Boston, MA (United States); Orbach, Darren B. [Boston Children' s Hospital, Neurointerventional Radiology, Boston, MA (United States)

    2015-09-15

    Pediatric central nervous system (CNS) vascular anomalies include lesions found only in the pediatric population and also the full gamut of vascular lesions found in adults. Pediatric-specific lesions discussed here include infantile hemangioma, vein of Galen malformation and dural sinus malformation. Some CNS vascular lesions that occur in adults, such as arteriovenous malformation, have somewhat distinct manifestations in children, and those are also discussed. Additionally, children with CNS vascular malformations often have associated broader vascular conditions, e.g., PHACES (posterior fossa anomalies, hemangioma, arterial anomalies, cardiac anomalies, eye anomalies and sternal anomalies), hereditary hemorrhagic telangiectasia, and capillary malformation-arteriovenous malformation syndrome (related to the RASA1 mutation). The treatment of pediatric CNS vascular malformations has greatly benefited from advances in endovascular therapy, including technical advances in adult interventional neuroradiology. Dramatic advances in therapy are expected to stem from increased understanding of the genetics and vascular biology that underlie pediatric CNS vascular malformations. (orig.)

  19. Subclinical hypothyroidism after vascular complicated pregnancy

    NARCIS (Netherlands)

    Zanden, M. van der; Hop-de Groot, R.J.; Sweep, F.C.; Ross, H.A.; Heijer, M. den; Spaanderman, M.E.A.

    2013-01-01

    OBJECTIVE: Women with a history of vascular complicated pregnancy are at risk for developing remote cardiovascular disease. It is associated with underlying cardiovascular risk factors both jeopardizing trophoblast and vascular function. Subclinical hypothyroidism may relate to both conditions.

  20. ESRD QIP - Vascular Access - Payment Year 2018

    Data.gov (United States)

    U.S. Department of Health & Human Services — This dataset includes facility details, performance rates, vascular access topic measure score, and the state and national average measure scores for the vascular...

  1. NEURO-VASCULAR INJURIES ASSOCIATED WITH LIMB ...

    African Journals Online (AJOL)

    hi-tech

    2000-12-01

    Dec 1, 2000 ... Results: Road traffic accidents were the main cause of fractures associated with neuro- vascular ... the patients with vascular or nerve injury associated with fractures .... of traumatic aorto-iliac dissection injury in a child with.

  2. Hot pressing in conduit faults during lava dome extrusion: Insights from Mount St. Helens 2004-2008

    Science.gov (United States)

    Ryan, Amy G.; Friedlander, Elizabeth A.; Russell, James K.; Heap, Michael J.; Kennedy, Lori A.

    2018-01-01

    Rhyodacitic volcanoes such as Mount St. Helens (MSH), Soufrière Hills, Mount Unzen and Mount Pelée erupt spines mantled by layers of magma-derived cataclasite and fault gouge. MSH produced seven lava spines from 2004-2008 composed of low-porosity, compositionally uniform, crystalline dacite. Dome extrusion was attended by continuous 'drumbeat' seismicity, derived from faulting along the conduit margin at 0.5-1 km depth, and evidenced by the enveloping gouge layers. We describe the properties of the gouge-derived fault rocks, including laboratory measurements of porosity and permeability. The gouge varies from unconsolidated powder to lithified low-porosity low-permeability fault rocks. We reconstruct the subsurface ascent of the MSH magma using published field observations and create a model that reconciles the diverse properties of the gouge with conditions in the conduit during ascent (i.e. velocity, temperature). We show lithification of the gouge to be driven by 'hot pressing' processes, wherein the combination of elevated temperature, confining pressure and dwell-time cause densification and solid-state sintering of the comminuted, crystal-rich (glass-poor) gouge. The degree of gouge lithification corresponds with residence time in the conduit such that well-lithified materials reflect extended times in the subsurface due to slower ascent rates. With this insight, we suggest that gouge competence can be used as a first-order estimate of lava ascent rates. Furthermore we posit gouge lithification, which reduces porosity and permeability, inhibits volcanic outgassing thereby increasing the potential for explosive events at spine-producing volcanoes.

  3. Ileal conduit without cystectomy may be an appropriate option in the treatment of intractable bladder pain syndrome/interstitial cystitis

    DEFF Research Database (Denmark)

    Norus, Thomas; Fode, Mikkel; Nordling, Jørgen

    2014-01-01

    OBJECTIVE: The aim of this study was to report the outcomes of urinary diversion for bladder pain syndrome/interstitial cystitis (BPS/IC) at a large university hospital over a period of more than 10 years. MATERIAL AND METHODS: Chart reviews were performed for BPS/IC patients who had undergone...... group and the non-cystectomy group with regard to the proportion of patients who were symptom free. CONCLUSION: Ileal conduit without cystectomy may be an appropriate option when performing urinary diversion in BPS/IC patients....

  4. A pilot muon radiography to image the shallow conduit of the Stromboli volcano: results and future prospects

    Science.gov (United States)

    Miyamoto, Seigo; Tioukov, Valeri; Sirignano, Chiara; Bozza, Cristiano; Morishima, Kunihiro

    2017-04-01

    The test result of imaging the shallow part of the Stromboli crater zone by using cosmic-ray muons in 2012 and possible performance of the future muon observation will be presented. It is well known that the behavior of volcanic eruptions strongly depends on the shape of the conduit. Stromboli is one of the most known and studied active volcanoes in the world, nevertheless the details of its internal structure are not well defined yet. Geophysical exploration method which use high energy cosmic-ray muons and makes the density image of the object like X-ray radiography for the human body is called "muon radiography " or "muography". A pilot muography was done for the shallow part of Stromboli in 2012. We succeeded to clarify that there is a less density part at the North-East cone in the crater zone. It is considered that the stack of volcanic ashes. On the other hand, we also confirmed that the contamination of the physical background particles and they makes the noisy density image especially about 50 meter below from the top of the crater. In another observation, Nishiyama et al (2014) revealed the contents of background particles and the way to remove them were presented. They showed that the main contents of the background particles is low kinetic energy charged particles and also showed that it is possible to remove them by using multi-layerd muon film detector. We can plan the future muography observation to see the deeper part of the conduit( at least until 100 meter from the top of crater) by their backgroundless method. Therefore we estimated possible performance of the future observation by multi-layer muon films. The result suggests that we might get the image of shallow conduit from the surface to the depth of e.g. 55 meter with 20 meter spatial resolution or 100 meter with 27 meter resolution in case the density in the conduit is 0.0 g/cm3 and with 71 percent statistical confidence level.

  5. Self-management of vascular risk factors

    OpenAIRE

    Sol-de Rijk, B.G.M.

    2009-01-01

    Summary The aim of this thesis was to provide insight into the potential of a self-management approach in treatment of vascular risk factors and to develop a self-management intervention. Furthermore to examine if this intervention, based on self-efficacy promoting theory, is effective in reducing vascular risk factors in patients with established vascular diseases. Patients with different manifestations of vascular diseases appeared to have high levels of self-efficacy concerning the self-ma...

  6. Vascular smooth muscle function: defining the diabetic vascular phenotype.

    Science.gov (United States)

    Bruno, Rosa Maria; Ghiadoni, Lorenzo

    2013-10-01

    In this issue of Diabetologia, a meta-analysis performed by Montero and co-authors (Diabetologia doi 10.1007/s00125-013-2974-1 ) demonstrates a significant impairment of vascular smooth muscle (VSM) function in type 2 diabetic patients. Endothelial function and VSM function between type 2 diabetic and healthy individuals were associated, especially in the microcirculation, confirming the hypothesis that unresponsiveness of VSM cells to NO may amplify the consequences of reduced NO availability. This study suggests a novel interpretation for endothelial dysfunction in diabetic patients, indicating VSM cells as key players. Causative mechanisms of VSM dysfunction, which seems to be a feature of the vascular phenotype of type 2 diabetes mellitus, are largely unexplored in humans. Future studies should also address the crucial issue of the prognostic significance of VSM dysfunction in diabetic patients, and possibly in other conditions characterised by high cardiovascular risk.

  7. Specificity of haemostasis abnormalities for vascular phenotypes.

    Science.gov (United States)

    Lowe, G D; Haverkate, F

    1998-01-01

    Atherothrombosis is a systemic disease, hence it is difficult to prove the specificity of haemostasis abnormality for any single vascular phenotype. Associations between haemostatic variables and any given phenotype, e.g. (vascular) dementia, should be interpreted with caution, given the overlaps of vascular disease phenotypes, risk factors, and haemostatic variables.

  8. 21 CFR 870.4450 - Vascular clamp.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Vascular clamp. 870.4450 Section 870.4450 Food and... CARDIOVASCULAR DEVICES Cardiovascular Surgical Devices § 870.4450 Vascular clamp. (a) Identification. A vascular clamp is a surgical instrument used to occlude a blood vessel temporarily. (b) Classification. Class II...

  9. Hippocampal atrophy in subcortical vascular dementia

    NARCIS (Netherlands)

    van de Pol, L.A.; Gertz, H.J.; Scheltens, P.; Wolf, H

    2011-01-01

    Background and Purpose: New research criteria for subcortical vascular dementia (SVaD) have been suggested to define a more homogeneous subgroup of vascular dementia. Hippocampal (Hc) atrophy is a hallmark of Alzheimer's disease (AD), but it also occurs in other dementia disorders including vascular

  10. Construction of nerve guide conduits from cellulose/soy protein composite membranes combined with Schwann cells and pyrroloquinoline quinone for the repair of peripheral nerve defect

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Lihua [Department of Biomedical Engineering, School of Basic Medical Sciences, Wuhan University, Wuhan 430071 (China); Center of Molecular Medicine, School of Medicine, Hubei University of Arts and Sciences, Xiangyang 441053 (China); Gan, Li; Liu, Yongming; Tian, Weiqun; Tong, Zan [Department of Biomedical Engineering, School of Basic Medical Sciences, Wuhan University, Wuhan 430071 (China); Wang, Xiong; Huselstein, Celine [Ingénierie Moléculaire et Physiopathologie Articulaire (IMoPA), UMR 7365 CNRS – Université de Lorraine, Biopôle, 54500 Vandoeuvre-lès-Nancy (France); Chen, Yun, E-mail: yunchen@whu.edu.cn [Department of Biomedical Engineering, School of Basic Medical Sciences, Wuhan University, Wuhan 430071 (China)

    2015-02-20

    Regeneration and functional reconstruction of peripheral nerve defects remained a significant clinical challenge. Nerve guide conduits, with seed cells or neurotrophic factors (NTFs), had been widely used to improve the repair and regeneration of injured peripheral nerve. Pyrroloquinoline quinone (PQQ) was an antioxidant that can stimulate nerve growth factors (NGFs) synthesis and accelerate the Schwann cells (SCs) proliferation and growth. In present study, three kinds of nerve guide conduits were constructed: one from cellulose/SPI hollow tube (CSC), another from CSC combined with SCs (CSSC), and the third one from CSSC combined with PQQ (CSSPC), respectively. And then they were applied to bridge and repair the sciatic nerve defect in rats, using autograft as control. Effects of different nerve guide conduits on the nerve regeneration were comparatively evaluated by general analysis, sciatic function index (SFI) and histological analysis (HE and TEM). Newly-formed regenerative nerve fibers were observed and running through the transparent nerve guide conduits 12 weeks after surgery. SFI results indicated that the reconstruction of motor function in CSSPC group was better than that in CSSC and CSC groups. HE images from the cross-sections and longitudinal-sections of the harvested regenerative nerve indicated that regenerative nerve fibers had been formed and accompanied with new blood vessels and matrix materials in the conduits. TEM images also showed that lots of fresh myelinated and non-myelinated nerve fibers had been formed. Parts of vacuolar, swollen and abnormal axons occurred in CSC and CSSC groups, while the vacuolization and swell of axons was the least serious in CSSPC group. These results indicated that CSSPC group had the most ability to repair and reconstruct the nerve structure and functions due to the comprehensive contributions from hollow CSC tube, SCs and PQQ. As a result, the CSSPC may have the potential for the applications as nerve guide

  11. Relaxin as a natural agent for vascular health

    Directory of Open Access Journals (Sweden)

    Daniele Bani

    2008-06-01

    Full Text Available Daniele BaniDepartment of Anatomy, Histology and Forensic Medicine, Sect. Histology, University of Florence, ItalyAbstract: Hypertension, atherothrombosis, myocardial infarction, stroke, peripheral vascular disease, and renal failure are the main manifestations of cardiovascular disease (CVD, the leading cause of death and disability in developed countries. Continuing insight into the pathophysiology of CVD can allow identification of effective therapeutic strategies to reduce the occurrence of death and/or severe disabilities. In this context, a healthy endothelium is deemed crucial to proper functioning and maintenance of anatomical integrity of the vascular system in many organs. Of note, epidemiologic studies indicate that the incidence of CVD in women is very low until menopause and increases sharply thereafter. The loss of protection against CVD in post-menopausal women has been chiefly attributed to ovarian steroid deficiency. However, besides steroids, the ovary also produces the peptide hormone relaxin (RLX, which provides potent vasoactive effects which render it the most likely candidate as the elusive physiological shield against CVD in fertile women. In particular, RLX has a specific relaxant effect on peripheral and coronary vasculature, exerted by the stimulation of endogenous nitric oxide (NO generation by cells of the vascular wall, and can induce angiogenesis. Moreover, RLX inhibits the activation of inflammatory leukocytes and platelets, which play a key role in CVD. Experimental studies performed in vascular and blood cell in vitro and in animal models of vascular dysfunction, as well as pioneer clinical observations, have provided evidence that RLX can prevent and/or improve CVD, thus offering background to clinical trials aimed at exploring the broad therapeutic potential of human recombinant RLX as a new cardiovascular drug.Keywords: relaxin, blood vessels, endothelial cells, vascular smooth muscle, nitric oxide

  12. Effects of longitudinal stretch on VSM tone and distensibility of muscular conduit arteries.

    Science.gov (United States)

    Zulliger, Martin A; Kwak, Naomi T M R; Tsapikouni, Theodora; Stergiopulos, Nikos

    2002-12-01

    With progressing age, large arteries diminish their longitudinal stretch, which in extreme cases results in tortuosity. Increased age is also associated with loss of vessel distensibility. We measured pressure-diameter curves from muscular porcine carotid arteries ex vivo at different longitudinal stretch ratios (lambda(z) = 1.4 and 1.8) and under different vascular smooth muscle (VSM) conditions (fully relaxed, normal VSM tone, and maximally contracted). Distensibility was found to be halved by decreasing longitudinal stretch from lambda(z) = 1.8 to 1.4 at physiological pressures. This counterintuitive observation is possible because highly nonlinear elastic modulus of the artery and anisotropic properties. Furthermore, a significantly larger basal VSM contraction was observed at lambda(z) = 1.8 than 1.4, although this was clearly not related to a myogenic response during inflation. This dependence of VSM tone to longitudinal stretch may have possible implications on the functional characteristics of the arterial wall.

  13. The effect of bioresorbable vascular scaffold implantation on distal coronary endothelial function in dyslipidemic swine with and without diabetes.

    Science.gov (United States)

    van den Heuvel, Mieke; Sorop, Oana; van Ditzhuijzen, Nienke S; de Vries, René; van Duin, Richard W B; Krabbendam-Peters, Ilona; van Loon, Janine E; de Maat, Moniek P; van Beusekom, Heleen M; van der Giessen, Wim J; Danser, A H Jan; Duncker, Dirk J

    2017-11-20

    We studied the effect of bioresorbable vascular scaffold (BVS) implantation on distal coronary endothelial function, in swine on a high fat diet without (HFD) or with diabetes (DM+HFD). Five DM+HFD and five HFD swine underwent BVS implantation on top of coronary plaques, and were studied six months later. Conduit artery segments >5mm proximal and distal to the scaffold and corresponding control segments of non-scaffolded coronary arteries, as well as segments of small arteries within the flow-territories of scaffolded and non-scaffolded arteries were harvested for in vitro vasoreactivity studies. Conduit segments proximal and distal to the BVS edges showed reduced endothelium-dependent vasodilation as compared to control vessels (p<0.01), with distal segments being most prominently affected (p<0.01). Endothelial dysfunction was only observed in DM+HFD swine and was principally due to a loss of NO. Endothelium-independent vasodilation and vasoconstriction were unaffected. Surprisingly, segments from the microcirculation distal to the BVS showed enhanced endothelium-dependent vasodilation (p<0.01), whereas endothelium-independent vasodilation and vasoconstriction were unaltered. This enhanced vasorelaxation was only observed in DM+HFD swine, and did not appear to be either NO- or EDHF-mediated. Six months of BVS implantation in DM+HFD swine causes NO-mediated endothelial dysfunction in nearby coronary segments, which is accompanied by a, possibly compensatory, increase in endothelial function of the distal microcirculation. Endothelial dysfunction extending into coronary conduit segments beyond the implantation-site, is in agreement with recent reports expressing concern for late scaffold thrombosis and of early BVS failure in diabetic patients. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  14. Three-layer microfibrous peripheral nerve guide conduit composed of elastin-laminin mimetic artificial protein and poly(L-lactic acid)

    Science.gov (United States)

    Kakinoki, Sachiro; Nakayama, Midori; Moritan, Toshiyuki; Yamaoka, Tetsuji

    2014-07-01

    We developed a microfibrous poly(L-lactic acid) (PLLA) nerve conduit with a three-layered structure to simultaneously enhance nerve regeneration and prevent adhesion of surrounding tissue. The inner layer was composed of PLLA microfiber containing 25% elastin-laminin mimetic protein (AG73-(VPGIG)30) that promotes neurite outgrowth. The thickest middle layer was constructed of pure PLLA microfibers that impart the large mechanical stremgth to the conduit. A 10% poly(ethylene glycol) was added to the outer layer to prevent the adhesion with the surrounding tissue. The AG73-(VPGIG)30 composisting of an elastin-like repetitive sequence (VPGIG)30 and a laminin-derived sequence (RKRLQVQLSIRT: AG73) was biosynthesized using Escherichia coli. The PLLA microfibrous conduits were fabricated using an electrospinning procedure. AG73-(VPGIG)30 was successfully mixed in the PLLA microfibers, and the PLLA/AG73-(VPGIG)30 microfibers were stable under physiological conditions. The PLLA/AG73-(VPGIG)30 microfibers enhanced adhesion and neurite outgrowth of PC12 cells. The electrospun microfibrous conduit with a three-layered structure was implanted for bridging a 2.0-cm gap in the tibial nerve of a rabbit. Two months after implantation, no adhesion of surrounding tissue was observed, and the action potential was slightly improved in the nerve conduit with the PLLA/AG73-(VPGIG)30 inner layer.

  15. Insights into Focused Fluid Conduit Formation from Comparing Seismic Chimneys and Pipes with Field Observations of Fluid Flow Manifestations in the Colorado Plateau

    Science.gov (United States)

    Karstens, J.; Berndt, C.

    2014-12-01

    The understanding of focused fluid flow in sedimentary basins builds on field geological observations and the interpretation of reflection seismic data, where fluid conduits manifest as anomalous amplitude patterns known as seismic chimneys or pipes. Seismic data is the most effective method for the analysis of entire fluid flow systems by constraining subsurface geometries, fluid accumulations and permeability barriers, but seismic data cannot provide information about the internal architecture, interaction with the bedrock and flow processes due to its coarse resolution. Field geological investigations of fluid conduit outcrops are capable of filling observation gaps on a sub-seismic scale and help constrain formation dynamics as well as hydraulic properties of fluid conduits and the bedrock. Here, we show that it is possible to correlate specific amplitude patterns of seismic chimneys with field observation of focused fluid conduits from the Colorado Plateau. The migrating fluids (gas, water, fluidized sediment) and their formation dynamics, which can be associated with different types of conduits (fractures, fluidizations, injections), result in distinguishable seismic signatures. These constrains improve the qualitative interpretation of seismic chimneys by adding information about migration and formation characteristics. A further integration of field geological and seismic investigation of focused fluid flow structures may help to quantify their hydraulic properties and how these evolve with time, which has important implications for the hydrocarbon prospection and the subsurface storage of wastewater and CO2.

  16. Identification of localised recharge and conduit flow by combined analysis of hydraulic and physico-chemical spring responses (Urenbrunnen, SW-Germany)

    Science.gov (United States)

    Birk, Steffen; Liedl, Rudolf; Sauter, Martin

    2004-01-01

    Karst aquifers are highly vulnerable to contamination due to the rapid transport of pollutants in conduit systems. Effective strategies for the management and protection of karst aquifers, therefore, require an adequate hydrogeological characterisation of the conduit systems. In particular, the identification and characterisation of conduits transmitting rapid, localised recharge to springs is of great interest for vulnerability assessments. In this work, it is demonstrated that localised recharge and conduit flow in a karst aquifer (Urenbrunnen catchment, southwest Germany) can be characterised by jointly analysing the hydraulic and physico-chemical responses of a spring to recharge events. Conduit volumes are estimated by evaluating time lags between increases in spring discharge and associated changes in the electrical conductivity and temperature of the discharged water. These estimates are confirmed by the results of a combined tracer and recharge test. Variations in electrical conductivity are also shown to assist in the quantification of the fast recharge component associated with short-term recharge pulses. However, spectral analysis of temperature fluctuations reveals that highly mineralised surface waters locally infiltrate into the aquifer during the winter and spring without causing significant electrical conductivity variations in the spring water. Hence, the most consistent conceptual model is obtained by a combined analysis of both physico-chemical parameters.

  17. Three-layer microfibrous peripheral nerve guide conduit composed of elastin-laminin mimetic artificial protein and poly(L-lactic acid

    Directory of Open Access Journals (Sweden)

    Sachiro eKakinoki

    2014-07-01

    Full Text Available We developed a microfibrous poly(L-lactic acid (PLLA nerve conduit with a three-layered structure to simultaneously enhance nerve regeneration and prevent adhesion of surrounding tissue. The inner layer was composed of PLLA microfiber containing 25% elastin-laminin mimetic protein (AG73-(VPGIG30 that promotes neurite outgrowth. The thickest middle layer was constructed of pure PLLA microfibers that impart the large mechanical stremgth to the conduit. A 10% poly(ethylene glycol was added to the outer layer to prevent the adhesion with the surrounding tissue. The AG73-(VPGIG30 composisting of an elastin-like repetitive sequence (VPGIG30 and a laminin-derived sequence (RKRLQVQLSIRT: AG73 was biosynthesized using Escherichia coli. The PLLA microfibrous conduits were fabricated using an electrospinning procedure. AG73-(VPGIG30 was successfully mixed in the PLLA microfibers, and the PLLA/AG73-(VPGIG30 microfibers were stable under physiological conditions. The PLLA/AG73-(VPGIG30 microfibers enhanced adhesion and neurite outgrowth of PC12 cells. The electrospun microfibrous conduit with a three-layered structure was implanted for bridging a 2.0-cm gap in the tibial nerve of a rabbit. Two months after implantation, no adhesion of surrounding tissue was observed, and the action potential was slightly improved in the nerve conduit with the PLLA/AG73-(VPGIG30 inner layer.

  18. Comparison of Direct Site Endovascular Repair Utilizing Expandable PTFE Stent Grafts Vs. Standard Vascular Shunts in a Porcine (Sus Scrofa) Model.

    Science.gov (United States)

    Davidson, Anders J; Neff, Lucas P; Grayson, J Kevin; Clement, Nathan F; DeSoucy, Erik S; Simon-Logan, Meryl A; Abbot, Christopher M; Sampson, James B; Williams, Timothy K

    2017-07-08

    The small diameter of temporary vascular shunts for vascular trauma management may restrict flow and result in ischemia or early thrombosis. We have previously reported a clinical experience with direct, open surgical reconstruction using expanded polytetrafluoroethylene (ePTFE) stent grafts to create a "sutureless" anastomosis as an alternative to standard temporary vascular shunts. We sought to characterize patency and flow characteristics of these grafts compared to standard shunts in a survival model of porcine vascular injury. 12 Yorkshire-cross swine received a 2cm long near-circumferential defect in the bilateral iliac arteries. A14-French Argyle shunt was inserted into one randomly assigned artery, with a self-expanding ePTFE stent deployed in the other. At 72 hours, conduit patency was evaluated by angiography. Arterial flow measurements were obtained at baseline, immediately after intervention, and after 72 hours via direct measurement with perivascular flow meters. Blood pressure proximal and distal to the conduits and arterial samples for histopathology were obtained during the terminal procedure. Angiography revealed no difference in patency at 72 hours (P=1.0). While there was no difference in baseline arterial flow between arteries (P=0.63), the stent grafts demonstrated significantly improved blood flow compared to shunts both immediately after intervention (390±36mL/min vs 265±25mL/min, p=0.002) and at 72 hours (261±29mL/min vs 170±36mL/min, p=0.005). The pressure gradient across the shunts was greater than that of the stent grafts (11.5mmHg IQR[3-19] vs. 3mmHg IQR[3-5], p=0.013). The speed of deployment was similar between the two devices. Open "sutureless" direct site repair using commercially available stent grafts to treat vascular injury is a technically feasible strategy for damage control management of peripheral vascular injury and offers increased blood flow when compared to temporary shunts. Furthermore, stent grafts may offer

  19. Comparison of direct site endovascular repair utilizing expandable polytetrafluoroethylene stent grafts versus standard vascular shunts in a porcine (Sus scrofa) model.

    Science.gov (United States)

    Davidson, Anders J; Neff, Lucas P; Grayson, J Kevin; Clement, Nathan F; DeSoucy, Erik S; Simon Logan, Meryl A; Abbot, Christopher M; Sampson, James B; Williams, Timothy K

    2017-09-01

    The small diameter of temporary vascular shunts for vascular trauma management may restrict flow and result in ischemia or early thrombosis. We have previously reported a clinical experience with direct, open surgical reconstruction using expandable polytetrafluoroethylene stent grafts to create a "sutureless" anastomosis as an alternative to standard temporary vascular shunts. We sought to characterize patency and flow characteristics of these grafts compared with standard shunts in a survival model of porcine vascular injury. Twelve Yorkshire-cross swine received a 2-cm-long near-circumferential defect in the bilateral iliac arteries. A 14 Fr Argyle shunt was inserted into one randomly assigned artery, with a self-expanding expandable polytetrafluoroethylene stent deployed in the other. At 72 hours, conduit patency was evaluated by angiography. Arterial flow measurements were obtained at baseline, immediately after intervention, and after 72 hours via direct measurement with perivascular flow meters. Blood pressure proximal and distal to the conduits and arterial samples for histopathology were obtained during the terminal procedure. Angiography revealed no difference in patency at 72 hours (p = 1.0). While there was no difference in baseline arterial flow between arteries (p = 0.63), the stent grafts demonstrated significantly improved blood flow compared with shunts both immediately after intervention (390 ± 36 mL/min vs. 265 ± 25 mL/min, p = 0.002) and at 72 hours (261 ± 29 mL/min vs. 170 ± 36 mL/min, p = 0.005). The pressure gradient across the shunts was greater than that of the stent grafts (11.5 mm Hg [interquartile range, 3-19 mm Hg] vs. 3 mm Hg [interquartile range, 3-5 mm Hg], p = 0.013). The speed of deployment was similar between the two devices. Open "sutureless" direct site repair using commercially available stent grafts to treat vascular injury is a technically feasible strategy for damage control management of peripheral vascular injury and

  20. Near-infraread spectroscopy during peripheral vascular surgery

    DEFF Research Database (Denmark)

    Schroeder, Torben Veith; Eiberg, Jonas Peter; Vogt, Katja

    1997-01-01

    Original,Near-infraread spectroscopy,Vascular disease,Vascular by-pass surgery,Perioperative oxymetry......Original,Near-infraread spectroscopy,Vascular disease,Vascular by-pass surgery,Perioperative oxymetry...

  1. [Menopause: Hypertension and vascular disease].

    Science.gov (United States)

    Zilberman, J M

    2018-01-28

    Hypertension is the main cardiovascular risk factor affecting 25% of women. Hormone changes and hypertension after menopause may lead to higher target organ damage and cardiovascular disease such as increased arterial stiffness, coronary diseases, chronic heart failure and stroke. The physiopathological mechanisms involved in the development of hypertension and cardiovascular diseases in menopausal women are controversial. There are pharmacokinetic and pharmacodynamic differences in both sexes, the women have more coughing when using the converting-enzyme inhibitors, more cramps when using thiazide diuretics and more oedema in the inferior limbs when using calcium antagonists. The aim of this review is to analyse possible physiopathological mechanisms involved in hypertension after menopause and to gain a better understanding of the biological effects mediated by vascular ageing in women when the level of oestrogen protective effect decreases over the vascular system. Copyright © 2017 SEH-LELHA. Publicado por Elsevier España, S.L.U. All rights reserved.

  2. Exercise-induced brachial artery blood flow and vascular function is impaired in systemic sclerosis.

    Science.gov (United States)

    Machin, Daniel R; Clifton, Heather L; Garten, Ryan S; Gifford, Jayson R; Richardson, Russell S; Wray, D Walter; Frech, Tracy M; Donato, Anthony J

    2016-12-01

    Systemic sclerosis (SSc) is a rare autoimmune disease characterized by debilitating fibrosis and vascular dysfunction; however, little is known about the circulatory response to exercise in this population. Therefore, we examined the peripheral hemodynamic and vasodilatory responses to handgrip exercise in 10 patients with SSc (61 ± 4 yr) and 15 age-matched healthy controls (56 ± 5 yr). Brachial artery diameter, blood flow, and mean arterial pressure (MAP) were determined at rest and during progressive static-intermittent handgrip exercise. Patients with SSc and controls were similar in body stature, handgrip strength, and MAP; however, brachial artery blood flow at rest was nearly twofold lower in patients with SSc compared with controls (22 ± 4 vs. 42 ± 5 ml/min, respectively; P exercise, there were no differences in MAP between the groups, exercise-induced hyperemia and therefore vascular conductance were ∼35% lower at all exercise workloads in patients with SSc (P exercise-induced brachial artery blood flow and conduit arterial vasodilatory dysfunction during handgrip exercise in SSc and suggest that elevated oxidative stress may play a role.

  3. Angiogenesis, Cancer, and Vascular Aging

    OpenAIRE

    Junji Moriya; Tohru Minamino

    2017-01-01

    Several lines of evidence have revealed that the angiogenic response to ischemic injury declines with age, which might account for the increased morbidity and mortality of cardiovascular disease (CVD) among the elderly. While impairment of angiogenesis with aging leads to delayed wound healing or exacerbation of atherosclerotic ischemic diseases, it also inhibits the progression of cancer. Age-related changes of angiogenesis have been considered to at least partly result from vascular aging o...

  4. Anatomy of a deep crustal volcanic conduit system; The Reinfjord Ultramafic Complex, Seiland Igneous Province, Northern Norway

    Science.gov (United States)

    Grant, Thomas B.; Larsen, Rune B.; Anker-Rasch, Lars; Grannes, Kim Rune; Iljina, Markku; McEnroe, Suzanne; Nikolaisen, Even; Schanche, Mona; Øen, Endre

    2016-05-01

    The Reinfjord Ultramafic Complex, Seiland Igneous Province represents a lower crustal magma chamber (25-30 km depth) that likely records a deep conduit system for mantle derived melts ascending through the continental crust. It consists of cumulates of dunite, wehrlite, olivine clinopyroxene as well as subordinate lherzolite and websterites, intruded into gabbro-norite and metasediment gneisses. Field, petrographic and geochemical data show that the intrusion developed through fractional crystallization and interactions between new batches of magma and partially solidified cumulates. This resulted in a 'reverse fractionation sequence' whereby cumulates became progressively more MgO and olivine rich with time. Contamination by partial melting of the gabbro-norite is evident in the marginal zones, but is limited in the central parts of the intrusion. Interrupted crystallization sequences of olivine → olivine + clinopyroxene and the absence of significant amounts of more evolved melts, suggests that large volumes of melt passed through the system to shallower levels in the crust leaving behind the cumulate sequences observed at Reinfjord. Therefore, the Reinfjord Ultramafic Complex represents a deep crustal conduit system, through which mantle derived melts passed. The parent melts are likely to have formed from partial melting of mantle with residual garnet and clinopyroxene.

  5. Material properties and electrical stimulation regimens of polycaprolactone fumarate-polypyrrole scaffolds as potential conductive nerve conduits.

    Science.gov (United States)

    Moroder, Philipp; Runge, M Brett; Wang, Huan; Ruesink, Terry; Lu, Lichun; Spinner, Robert J; Windebank, Anthony J; Yaszemski, Michael J

    2011-03-01

    The mechanical and electrical properties of polycaprolactone fumarate-polypyrrole (PCLF-PPy) scaffolds were studied under physiological conditions to evaluate their ability to maintain the material properties necessary for application as conductive nerve conduits. PC12 cells cultured on PCLF-PPy scaffolds were stimulated with regimens of 10 μA of either a constant or a 20 Hz frequency current passed through the scaffolds for 1h per day. PC12 cellular morphologies were analyzed by fluorescence microscopy after 48 h. PCLF-PPy scaffolds exhibited excellent mechanical properties at 37 °C which would allow suturing and flexibility. The surface resistivity of the scaffolds was 2 kΩ and the scaffolds were electrically stable during the application of electrical stimulation (ES). In vitro studies showed significant increases in the percentage of neurite bearing cells, number of neurites per cell and neurite length in the presence of ES compared with no ES. Additionally, extending neurites were observed to align in the direction of the applied current. This study shows that electrically conductive PCLF-PPy scaffolds possess the material properties necessary for application as nerve conduits. Additionally, the capability to significantly enhance and direct neurite extension by passing an electrical current through PCLF-PPy scaffolds renders them even more promising as future therapeutic treatments for severe nerve injuries. Copyright © 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  6. Material properties and electrical stimulation regimens through polycaprolactone fumarate-polypyrrole scaffolds as potential conductive nerve conduits

    Science.gov (United States)

    Moroder, Philipp; Wang, Huan; Ruesink, Terry; Lu, Lichun; Windebank, Anthony J.; Yaszemski, Michael J.; Runge, M. Brett

    2010-01-01

    Mechanical and electrical properties of polycaprolactone fumarate-polypyrrole (PCLF-PPy) scaffolds were studied under physiological conditions to evaluate their ability to maintain material properties necessary for application as conductive nerve conduits. PC12 cells cultured on PCLF-PPy scaffolds were stimulated with regimens of 10 μA of constant or 20 Hz frequency current passed through the scaffolds for 1 h/day. PC12 cellular morphologies were analyzed by fluorescence microscopy after 48 h. PCLF-PPy scaffolds exhibited excellent mechanical properties at 37°C which would allow suturing and flexibility. The surface resistivity of the scaffolds was 2kΩ and the scaffolds were electrically stable during application of electrical stimulation (ES). In vitro studies showed significant increases in percentage of neurite bearing cells, number of neurites per cell and neurite length in the presence of ES compared to no ES. Additionally, extending neurites were observed to align in the direction of the applied current. This study shows that electrically conductive PCLF-PPy scaffolds possess material properties necessary for application as nerve conduits. Additionally, the capability to significantly enhance and direct neurite extension by passing electrical current through PCLF-PPy scaffolds renders them even more promising as future therapeutic treatments for severe nerve injuries. PMID:20965280

  7. Laparoscopic ischemic conditioning of the stomach increases neovascularization of the gastric conduit in patients undergoing esophagectomy for cancer.

    Science.gov (United States)

    Pham, Thai H; Melton, Shelby D; McLaren, Patrick J; Mokdad, Ali A; Huerta, Sergio; Wang, David H; Perry, Kyle A; Hardaker, Hope L; Dolan, James P

    2017-09-01

    Gastric ischemic preconditioning has been proposed to improve blood flow and reduce the incidence of anastomotic complications following esophagectomy with gastric pull-up. This study aimed to evaluate the effect of prolonged ischemic preconditioning on the degree of neovascularization in the distal gastric conduit at the time of esophagectomy. A retrospective review of a prospectively maintained database identified 30 patients who underwent esophagectomy. The patients were divided into three groups: control (no preconditioning, n = 9), partial (short gastric vessel ligation only, n = 8), and complete ischemic preconditioning (left and short gastric vessel ligation, n = 13). Microvessel counts were assessed, using immunohistologic analysis to determine the degree of neovascularization at the distal gastric margin. The groups did not differ in age, gender, BMI, pathologic stage, or cancer subtype. Ischemic preconditioning durations were 163 ± 156 days for partial ischemic preconditioning, compared to 95 ± 50 days for complete ischemic preconditioning (P = 0.2). Immunohistologic analysis demonstrated an increase in microvessel counts of 29% following partial ischemic preconditioning (P = 0.3) and 67% after complete ischemic preconditioning (P gastric conduit. © 2017 Wiley Periodicals, Inc.

  8. Vascularization regenerative medicine and tissue engineering

    CERN Document Server

    Brey, Eric M

    2014-01-01

    A Complex and Growing Field The study of vascularization in tissue engineering and regenerative medicine (TERM) and its applications is an emerging field that could revolutionize medical approaches for organ and tissue replacement, reconstruction, and regeneration. Designed specifically for researchers in TERM fields, Vascularization: Regenerative Medicine and Tissue Engineering provides a broad overview of vascularization in TERM applications. This text summarizes research in several areas, and includes contributions from leading experts in the field. It defines the difficulties associated with multicellular processes in vascularization and cell-source issues. It presents advanced biomaterial design strategies for control of vascular network formation and in silico models designed to provide insight not possible in experimental systems. It also examines imaging methods that are critical to understanding vascularization in engineered tissues, and addresses vascularization issues within the context of specific...

  9. A bioreactor system for interfacial culture and physiological perfusion of vascularized tissue equivalents.

    Science.gov (United States)

    Groeber, Florian; Kahlig, Alexander; Loff, Steffan; Walles, Heike; Hansmann, Jan

    2013-03-01

    A pivotal requirement for the generation of vascularized tissue equivalents is the development of culture systems that provide a physiological perfusion of the vasculature and tissue-specific culture conditions. Here, we present a bioreactor system that is suitable to culture vascularized tissue equivalents covered with culture media and at the air-medium interface, which is a vital stimulus for skin tissue. For the perfusion of the vascular system a new method was integrated into the bioreactor system that creates a physiological pulsatile medium flow between 80 and 120 mmHg to the arterial inflow of the equivalent's vascular system. Human dermal microvascular endothelial cells (hDMECs) were injected into the vascular system of a biological vascularized scaffold based on a decellularized porcine jejunal segment and cultured in the bioreactor system for 14 days. Histological analysis and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) staining revealed that the hDMECs were able to recolonize the perfused vascular structures and expressed endothelial cell specific markers such as platelet endothelial cell adhesion molecule and von Willebrand factor. These results indicate that our bioreactor system can serve as a platform technology to generate advanced bioartificial tissues with a functional vasculature for future clinical applications. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Hawaiian fissure fountains: Quantifying vent and shallow conduit geometry, episode 1 of the 1969-1974 Mauna Ulu eruption: Chapter 17

    Science.gov (United States)

    Parcheta, Carolyn; Fagents, Sarah; Swanson, Donald A.; Houghton, Bruce F.; Ericksen, Todd; Carey, Rebecca; Cayol, Valérie; Poland, Michael P.; Weis, Dominique

    2015-01-01

    Geometries of shallow magmatic pathways feeding volcanic eruptions are poorly constrained, yet many key interpretations about eruption dynamics depend on knowledge of these geometries. Direct quantification is difficult because vents typically become blocked with lava at the end of eruptions. Indirect geophysical techniques have shed light on some volcanic conduit geometries, but the scales are too coarse to resolve narrow fissures (widths typically 1 m). Kīlauea's Mauna Ulu eruption, which started with geometry of a shallow magmatic pathway, as the western vents remain unobstructed to depths >30 m. Direct measurements at the ground surface were augmented by tripod-mounted lidar measurements to quantify the shallow conduit geometry for three vents at a resolution geometries have been used in computational modeling. Our data can provide more accurate conduit shapes for better understanding of shallow fissure fluid dynamics and how it controls eruptive behavior, especially if incorporated into computer models.

  11. Biodegradable chitin conduit tubulation combined with bone marrow mesenchymal stem cell transplantation for treatment of spinal cord injury by reducing glial scar and cavity formation.

    Science.gov (United States)

    Xue, Feng; Wu, Er-Jun; Zhang, Pei-Xun; Li-Ya, A; Kou, Yu-Hui; Yin, Xiao-Feng; Han, Na

    2015-01-01

    We examined the restorative effect of modified biodegradable chitin conduits in combination with bone marrow mesenchymal stem cell transplantation after right spinal cord hemisection injury. Immunohistochemical staining revealed that biological conduit sleeve bridging reduced glial scar formation and spinal muscular atrophy after spinal cord hemisection. Bone marrow mesenchymal stem cells survived and proliferated after transplantation in vivo, and differentiated into cells double-positive for S100 (Schwann cell marker) and glial fibrillary acidic protein (glial cell marker) at 8 weeks. Retrograde tracing showed that more nerve fibers had grown through the injured spinal cord at 14 weeks after combination therapy than either treatment alone. Our findings indicate that a biological conduit combined with bone marrow mesenchymal stem cell transplantation effectively prevented scar formation and provided a favorable local microenvironment for the proliferation, migration and differentiation of bone marrow mesenchymal stem cells in the spinal cord, thus promoting restoration following spinal cord hemisection injury.

  12. Biodegradable chitin conduit tubulation combined with bone marrow mesenchymal stem cell transplantation for treatment of spinal cord injury by reducing glial scar and cavity formation

    Directory of Open Access Journals (Sweden)

    Feng Xue

    2015-01-01

    Full Text Available We examined the restorative effect of modified biodegradable chitin conduits in combination with bone marrow mesenchymal stem cell transplantation after right spinal cord hemisection injury. Immunohistochemical staining revealed that biological conduit sleeve bridging reduced glial scar formation and spinal muscular atrophy after spinal cord hemisection. Bone marrow mesenchymal stem cells survived and proliferated after transplantation in vivo, and differentiated into cells double-positive for S100 (Schwann cell marker and glial fibrillary acidic protein (glial cell marker at 8 weeks. Retrograde tracing showed that more nerve fibers had grown through the injured spinal cord at 14 weeks after combination therapy than either treatment alone. Our findings indicate that a biological conduit combined with bone marrow mesenchymal stem cell transplantation effectively prevented scar formation and provided a favorable local microenvironment for the proliferation, migration and differentiation of bone marrow mesenchymal stem cells in the spinal cord, thus promoting restoration following spinal cord hemisection injury.

  13. Microfluidic Bioprinting for Engineering Vascularized Tissues and Organoids.

    Science.gov (United States)

    Zhang, Yu Shrike; Pi, Qingmeng; van Genderen, Anne Metje

    2017-08-11

    Engineering vascularized tissue constructs and organoids has been historically challenging. Here we describe a novel method based on microfluidic bioprinting to generate a scaffold with multilayer interlacing hydrogel microfibers. To achieve smooth bioprinting, a core-sheath microfluidic printhead containing a composite bioink formulation extruded from the core flow and the crosslinking solution carried by the sheath flow, was designed and fitted onto the bioprinter. By blending gelatin methacryloyl (GelMA) with alginate, a polysaccharide that undergoes instantaneous ionic crosslinking in the presence of select divalent ions, followed by a secondary photocrosslinking of the GelMA component to achieve permanent stabilization, a microfibrous scaffold could be obtained using this bioprinting strategy. Importantly, the endothelial cells encapsulated inside the bioprinted microfibers can form the lumen-like structures resembling the vasculature over the course of culture for 16 days. The endothelialized microfibrous scaffold may be further used as a vascular bed to construct a vascularized tissue through subsequent seeding of the secondary cell type into the interstitial space of the microfibers. Microfluidic bioprinting provides a generalized strategy in convenient engineering of vascularized tissues at high fidelity.

  14. Vascular Endothelial Growth Factor from Embryonic Status to Cardiovascular Pathology

    Directory of Open Access Journals (Sweden)

    Mohsen Azimi-Nezhad

    2014-05-01

    Full Text Available Vascular endothelial growth factor (VEGF is a multifunctional cytokine with distinct functions in angiogenesis, lymphangiogenesis, vascular permeability, and hematopoiesis. VEGF is a highly conserved, disulfide-bonded dimeric glycoprotein of 34 to 45 kDa produced by several cell types including fibroblasts, neutrophils, endothelial cells, and peripheral blood mononuclear cells, particularly T lymphocytes and macrophages. Six VEGF isoforms are generated as a result of alternative splicing from a single VEGF gene, consisting of 121, 145, 165, 183, 189, or 206 amino acids. VEGF121, VEGF145, and VEGF165 are secreted whereas VEGF183, VEGF189, and VEGF206 are cell membrane-bound. VEGF145 has a key role during the vascularization of the human ovarian follicle and corpus luteum, in the placentation and embryonic periods, and in bone and wound healing, while VEGF165 is the most abundant and biologically active isoform. VEGF has been linked with a number of vascular pathologies including cardiovascular diseases such ischemic heart disease, heart failure, stroke, and diabetes and its related complications. In this review we aimed to present some important roles of VEGF in a number of clinical issues and indicate its involvement in several phenomena from the initial steps of the embryonic period to cardiovascular diseases.

  15. Vascular versus tubular renin: role in kidney development.

    Science.gov (United States)

    Sequeira-Lopez, Maria Luisa S; Nagalakshmi, Vidya K; Li, Minghong; Sigmund, Curt D; Gomez, R Ariel

    2015-09-15

    Renin, the key regulated enzyme of the renin-angiotensin system regulates blood pressure, fluid-electrolyte homeostasis, and renal morphogenesis. Whole body deletion of the renin gene results in severe morphological and functional derangements, including thickening of renal arterioles, hydronephrosis, and inability to concentrate the urine. Because renin is found in vascular and tubular cells, it has been impossible to discern the relative contribution of tubular versus vascular renin to such a complex phenotype. Therefore, we deleted renin independently in the vascular and tubular compartments by crossing Ren1(c fl/fl) mice to Foxd1-cre and Hoxb7-cre mice, respectively. Deletion of renin in the vasculature resulted in neonatal mortality that could be rescued with daily injections of saline. The kidneys of surviving mice showed the absence of renin, hypertrophic arteries, hydronephrosis, and negligible levels of plasma renin. In contrast, lack of renin in the collecting ducts did not affect kidney morphology, intra-renal renin, or circulating renin in basal conditions or in response to a homeostatic stress, such as sodium depletion. We conclude that renin generated in the renal vasculature is fundamental for the development and integrity of the kidney, whereas renin in the collecting ducts is dispensable for normal kidney development and cannot compensate for the lack of renin in the vascular compartment. Further, the main source of circulating renin is the kidney vasculature. Copyright © 2015 the American Physiological Society.

  16. The Malone Antegrade Continence Enema (MACE principle in children: is it important if the conduit is implanted in the left or the right colon?

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    Karine F. Meyer

    2008-03-01

    Full Text Available OBJECTIVE: The aim of the study was to determine which was the optimal side for the conduit to be placed (right or left colon for antegrade continence enema implantation. MATERIALS AND METHODS: Between July 1999 and March 2006, 31 patients underwent the construction of a catheterizable conduit using the Malone principle (MACE In 22 cases the conduit was re-implanted in the right colon and in 9 cases in the left colon. There were 20 male patients and 11 female patients, with a mean age of 10.23 years. The follow-up period varied from 3 from 83 months (average 25 months. Right and left implantation of the conduit in the colon were compared with regards to the presence of complications, volume of the solution utilized, frequency of colonic lavage, time needed for performing the enema, and degree of satisfaction. RESULTS: One patient with the conduit in the right colon, using the appendix, lost the mechanism after two month follow-up. Thirty patients remain clean and are all capable of performing self-catheterization. No statistically significant differences were found between the groups regarding the variables studied: complications (p = 1.000, solution volume (p = 0.996, time required (p = 0.790 and patient's rating (p = 0.670. The lavage frequency required for patients with the conduit in the right colon may be lower. CONCLUSION: The MACE principle was considered effective for treating fecal retention and leaks, independent of the implantation site. The success of this surgery appears to be directly related to the patient's motivation and not to the technique utilized.

  17. Conduit dynamics in transitional rhyolitic activity recorded by tuffisite vein textures from the 2008-2009 Chaitén eruption

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    Elodie eSaubin

    2016-05-01

    Full Text Available The mechanisms of hazardous silicic eruptions are controlled by complex, poorly-understood conduit processes. Observations of recent Chilean rhyolite eruptions have revealed the importance of hybrid activity, involving simultaneous explosive and effusive emissions from a common vent. Such behaviour hinges upon the ability of gas to decouple from magma in the shallow conduit. Tuffisite veins are increasingly suspected to be a key facilitator of outgassing, as they repeatedly provide a transient permeable escape route for volcanic gases. Intersection of foam domains by tuffisite veins appears critical to efficient outgassing. However, knowledge is currently lacking into textural heterogeneities within shallow conduits, their relationship with tuffisite vein propagation, and the implications for fragmentation and degassing processes. Similarly, the magmatic vesiculation response to upper conduit pressure perturbations, such as those related to the slip of dense magma plugs, remains largely undefined. Here we provide a detailed characterization of an exceptionally large tuffisite vein within a rhyolitic obsidian bomb ejected during transitional explosive-effusive activity at Chaitén, Chile in May 2008. Vein textures and chemistry provide a time-integrated record of the invasion of a dense upper conduit plug by deeper fragmented magma. Quantitative textural analysis reveals diverse vesiculation histories of various juvenile clast types.Using vesicle size distributions, bubble number densities, zones of diffusive water depletion, and glass H2O concentrations, we propose a multi-step degassing/fragmentation history, spanning deep degassing to explosive bomb ejection. Rapid decompression events of ~3-4 MPa are associated with fragmentation of foam and dense magma at ~200-350 metres depth in the conduit, permitting vertical gas and pyroclast mobility over hundreds of metres. Permeable pathway occlusion in the dense conduit plug by pyroclast accumulation

  18. Les inconvénients pour la sécurité routière de certains comportements de conduite courtois

    OpenAIRE

    FOURNIER, Jean-Yves; Clabaux, Nicolas

    2015-01-01

    La courtoisie au volant est généralement considérée comme porteuse de sécurité. À ce titre, elle fait l'objet de nombreuses campagnes de sensibilisation visant à promouvoir des comportements de conduite plus courtois entre usagers de la route. Il n'y a pourtant pas de travaux scientifiques traitant spécifiquement des liens entre comportements de conduite courtois et production d'accidents. Les travaux existants s'intéressent plutôt aux liens entre comportements agressifs, colériques et sécuri...

  19. Transgenic mice over-expressing ET-1 in the endothelial cells develop systemic hypertension with altered vascular reactivity.

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    Justin Wai-Chung Leung

    Full Text Available Endothelin-1 (ET-1 is a potent vasoconstrictor involved in the regulation of vascular tone and implicated in hypertension. However, the role of small blood vessels endothelial ET-1 in hypertension remains unclear. The present study investigated the effect of chronic over-expression of endothelial ET-1 on arterial blood pressure and vascular reactivity using transgenic mice approach. Transgenic mice (TET-1 with endothelial ET-1 over-expression showed increased in ET-1 level in the endothelial cells of small pulmonary blood vessels. Although TET-1 mice appeared normal, they developed mild hypertension which was normalized by the ET(A receptor (BQ123 but not by ET(B receptor (BQ788 antagonist. Tail-cuff measurements showed a significant elevation of systolic and mean blood pressure in conscious TET-1 mice. The mice also exhibited left ventricular hypertrophy and left axis deviation in electrocardiogram, suggesting an increased peripheral resistance. The ionic concentrations in the urine and serum were normal in 8-week old TET-1 mice, indicating that the systemic hypertension was independent of renal function, although, higher serum urea levels suggested the occurrence of kidney dysfunction. The vascular reactivity of the aorta and the mesenteric artery was altered in the TET-1 mice indicating that chronic endothelial ET-1 up-regulation leads to vascular tone imbalance in both conduit and resistance arteries. These findings provide evidence for the role of spatial expression of ET-1 in the endothelium contributing to mild hypertension was mediated by ET(A receptors. The results also suggest that chronic endothelial ET-1 over-expression affects both cardiac and vascular functions, which, at least in part, causes blood pressure elevation.

  20. Exercise training improves vascular function in adolescents with type 2 diabetes.

    Science.gov (United States)

    Naylor, Louise H; Davis, Elizabeth A; Kalic, Rachelle J; Paramalingam, Niru; Abraham, Mary B; Jones, Timothy W; Green, Daniel J

    2016-02-01

    The impact of exercise training on vascular health in adolescents with type 2 diabetes has not been previously studied. We hypothesized that exercise training would improve micro- and macrovascular health in adolescents with type 2 diabetes. Thirteen adolescents (13-21 years, 10F) with type 2 diabetes were recruited from Princess Margaret Hospital. Participants were randomized to receive either an exercise program along with standard clinical care (n = 8) or standard care alone (n = 5). Those in the intervention group received 12 weeks of gym-based, personalized, and supervised exercise training. Those in the control group were instructed to maintain usual activity levels. Assessments were conducted at baseline and following week 12. The exercise group was also studied 12 weeks following the conclusion of their program. Assessments consisted of conduit artery endothelial function (flow-mediated dilation, FMD) and microvascular function (cutaneous laser Doppler). Secondary outcomes included body composition (dual-energy X-ray absorptiometry, DXA), glycemic control (whole body insulin sensitivity, M) assessed using the euglycemic-hyperinsulinemic clamp protocol, cardiorespiratory fitness (V˙O2peak), and muscular strength (1RM). Exercise training increased FMD (P function (P function were reversed. This study indicates that exercise training can improve both conduit and microvascular endothelial function and health, independent of changes in insulin sensitivity in adolescents with type 2 diabetes. © 2016 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of the American Physiological Society and The Physiological Society.

  1. Ghrelin improves vascular autophagy in rats with vascular calcification.

    Science.gov (United States)

    Xu, Mingming; Liu, Lin; Song, Chenfang; Chen, Wei; Gui, Shuyan

    2017-06-15

    This study aimed to investigate whether ghrelin ameliorated vascular calcification (VC) through improving autophagy. VC model was induced by nicotine plus vitamin D 3 in rats and β-glycerophosphate in vascular smooth muscle cell (VSMC). Calcium deposition was detected by von Kossa staining or alizarin red S staining. ALP activity was also detected. Western blot was used to assess the protein expression. Ghrelin treatment attenuated the elevation of calcium deposition and ALP activity in VC model both in vivo and in vitro. Interesting, the protein levels of autophagy markers, LC3 and beclin1 were significantly upregulated by ghrelin in VC model. An autophagy inhibitor, 3-methyladenine blocks the ameliorative effect of ghrelin on VC. Furthermore, protein expressions of phosphate-AMPK were increased by ghrelin treatment both in calcified aorta and VSMC. The effect of ghrelin on autophagy induction and VC attenuation was prevented by AMPK inhibitor, compound C. Our results suggested that ghrelin improved autophagy through AMPK activation, which was resulted in VC amelioration. These data maybe throw light on prevention and therapy of VC. Copyright © 2016 Elsevier Inc. All rights reserved.

  2. Effect of vascular burden as measured by vascular indexes upon vascular dementia: a matched case-control study

    OpenAIRE

    Takahashi, Paul Y; Caldwell, Casey R; Targonski, Paul V

    2012-01-01

    Paul Y Takahashi, Casey R Caldwell, Paul V TargonskiPrimary Care Internal Medicine, Mayo Clinic, Rochester MN, USABackground: Vascular dementia (VaD) is a challenging illness that affects the lives of older adults and caregivers. It is unclear how multiple vascular risk factor exposures (polyvascular disease) affect VaD.Purpose: To determine the relationship between multiple vascular risk exposures, as counted on an index in cases with VaD, compared with healthy age-/gender-matched controls.M...

  3. The evolution of periodic seismicity, waveform similarity, and conduit processes during unrest episodes at Tungurahua volcano, Ecuador, in 2015

    Science.gov (United States)

    Bell, Andrew; Hernandez, Stephen; Gaunt, Elizabeth; Mothes, Patricia; Hidalgo, Silvana; Ruiz, Mario

    2016-04-01

    Tungurahua is a large andesitic stratovolcano located in the Andes of Ecuador. The current eruptive phase at Tungurahua began in 1999, and has been characterised by episodes of vulcanian and strombolian activity, interspersed by periods of relative quiescence. Despite showing only modest eruptive activity in 2015, seismic data revealed a pronounced change in the behaviour of the magma-conduit system compared to the preceding 15 years of activity. The change is most notable in the periodicity of interevent-times of volcanic earthquakes. Previous seismicity at Tungurahua is characterised by interevent-time periodicities typical of a Poisson process, or modestly clustered, with slightly elevated (anti-clustered) periodicities observed only rarely during vulcanian episodes. However, activity in 2015 saw a series of unrest episodes characterised by highly-periodic interevent-times, and including several notable episodes of 'drumbeat' earthquakes. Here we report seismic and associated geophysical signals recorded at Tungurahua in 2015 by the monitoring network of the Instituto Geofisico of Ecuador, their relation to conduit processes, and implications for the origins of unrest and likely future activity. Although the nature of the low-frequency seismic signals change both within and between unrest episodes, the underlying periodicity is more consistent and gradually evolving. Waveform similarity is high within phases, resulting from the repeated activation of persistent sources, but low between different episodes, suggesting the emergence of new sources and locations. The strength of periodicity is correlated with the average waveform similarity for all unrest episodes, with the relatively low waveform similarities observed for the highly periodic drumbeat earthquakes in April due to contamination from coexisting continuous tremor. Eruptive activity consisted of a few minor explosions and ash emission events. Notably, a short-lived episode of Strombolian activity in

  4. Vascular dementia: Facts and controversies

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    Pavlović Aleksandra

    2013-01-01

    Full Text Available Vascular dementia (VaD is the second most frequent dementia after Alzheimer’s disease, and is diagnosed during lifetime in 20% of demented patients. Five­year survival rate in VaD is 39%, while it is estimated to be 75% in healthy persons of the same age. It is therefore important to make correct diagnosis of VaD early in the course of the disease. Risk factors for VaD are identical to stroke risk factors, and there are significant possibilities for the prevention of vascular cognitive decline. Cognitive decline develops acutely or step­by­step within three months after stroke, but more gradual progression of intellectual decline is also possible. Neurological examination can reveal pyramidal and extrapyramidal signs, pseudobulbar palsy, gait disturbance and urinary incontinence. Neuropsychological profile comprises the loss of cognitive set shifting, decline in word fluency, verbal learning difficulties, perseverations, difficulties in complex figure copying, and in patients with cortically located lesions also problems with speech and praxia. The basis of the diagnosis is, besides history, neurological examination and neuropsychological assessment, computed tomography and/ or magnetic resonance brain imaging. Vascular risk factors control is the most important measure in VaD prevention. Modern guidelines for the treatment of cognitive decline in VaD emphasize that donepezil can be useful in the improvement of cognitive status at the level of Class IIa recommendation at the level of evidence A, while memantine may be useful in patients with mixed VaD and Alzheimer’s disease dementia. [Projekat Ministarstva nauke Republike Srbije, br. 175022 i br. 175033

  5. MIGRAINE AND STROKE: VASCULAR COMORBIDITY

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    Donata eGuidetti

    2014-10-01

    Full Text Available Several comorbidities are associated to migraine.Recent meta-analyses have consistently demonstrated a relationship between migraine and stroke, which is well-defined for ischaemic stroke and migraine with aura, even stronger in females on oral contraceptives or smokers. However, there seems to be no clear-cut association between stroke in migraineurs and the common vascular risk factors, at least in the young adult population. Migraineurs also run an increased risk of hemorrhagic stroke, while the association between migraine and cardiovascular disease remains poorly defined.Another aspect is the relationship between migraine and the presence of silent brain lesions. It has been demonstrated that there is an increased frequency of ischaemic lesions in the white matter of migraineurs, especially silent infarcts in the posterior circulation territory in patients with at least 10 attacks per month. Although there is a higher prevalence of patent foramen ovale (PFO in migraineurs, the relationship between migraine and PFO remains controversial and PFO closure is not a recommended procedure to prevent migraine. As an increased frequency of cervical artery dissections has been observed in migrainous patients, it has been hypothesized that migraine may represent a predisposing factor for