Search Results
Results 301 - 350 of 1562
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Ishiguro M - - 2008
Constriction of small (100-200 microm) diameter cerebral arteries in response to increased intravascular pressure plays an important role in the regulation of cerebral blood flow. In arteries from healthy animals, these pressure-induced constrictions arise from depolarization of arterial smooth muscle leading to enhanced activity of L-type voltage-dependent calcium channels. Recently, ...
Jakobsson Lars - - 2008
Angiogenesis is crucial in the progression of a number of pathological conditions, such as diabetic retinopathy, rheumatoid arthritis, psoriasis, and cancer. In contrast to vessels in healthy tissues, the vasculature in these pathologies is highly unstable, constantly dissolving and renewing. Characteristically, vessels in pathologies have discontinuous basement membrane (BM) coverage. ...
Taviani Valentina V Department of Engineering, University of Cambridge, CB21PZ UK. vt232@ - - 2008
The mechanical properties of arterial walls have long been recognized to play an essential role in the development and progression of cardiovascular disease (CVD). Early detection of variations in the elastic modulus of arteries would help in monitoring patients at high cardiovascular risk stratifying them according to risk. An in ...
Person Benjamin - - 2008
AIM: To compare the safety and efficacy of four energy-based vascular sealing and cutting instruments. METHODS: Blood vessels of various types and diameters were harvested from four pigs using four instruments: Harmonic ACE (Ethicon Endo-Surgery, Cincinnati, OH), LigaSure V and LigaSure Atlas (Valleylab, Inc., Boulder, CO; a division of Tyco ...
Wong Chin-Ho - - 2007
The propeller-type flap design is increasingly used in reconstructive surgery for various regions of the body. To date, determinants of perforator patency when subjected to twisting have not been elucidated. We propose a simulation model to study parameters affecting perforator patency under such conditions. Nonlinear finite element procedure was used ...
Bozlar U - - 2007
The range of the diameters of pulmonary arteries (PA) is not fully shown in the current literature. Contrast-enhanced computed tomography (CT) of the thorax might be used for measuring diameters of the PA. To determine the diameters of PAs in subjects with normal PA pressure by using thoracic CT. 126 ...
Sonoyama Kazuhiko - - 2007
At the level of the small artery, essential hypertension is associated with eutrophic inward remodeling. This involves reduction in lumen diameter by an increase in wall thickness. Previously thought to involve either hypertrophy or hyperplasia of the vascular smooth muscle cells in the media, it is now felt to be ...
Song Jin-Won - - 2008
We report the fabrication and characterization of doubly clamped multi-walled carbon nanotubes (MWNTs). The devices were assembled by applying an electric field while the MWNTs were firmly clamped and suspended at both ends of a thick metal trench electrode in solution. The contacts were further processed using a focused ion ...
Fulcher Lewis - - 2007
Pressure distributions for the uniform glottis were taken with a static physical model (M5) for the diameters d=0.005, 0.0075, 0.01, 0.02, 0.04, 0.08, 0.16, and 0.32 cm for a number of transglottal pressures of interest for phonation. At each pressure and diameter, entrance loss and exit coefficients are calculated. The ...
Rahmouni Kamal - - 2007
1. Leptin is a hormone that is secreted by adipocytes and delivered to the brain to regulate appetite and energy expenditure. Other effects of leptin include activation of the sympathetic nervous system and an increase in arterial pressure.2. Mounting evidence suggests that the sympathetic nervous system subserving different tissues is ...
Hruby Gregory W - - 2007
PURPOSE: Vessel sealing capabilities and the peripheral energy spread associated with currently available energy based surgical instruments were evaluated. MATERIALS AND METHODS: Four groups of energy based surgical instruments were established for evaluation, including the ACE, LCS-C5 (Ethicon, Cincinnati, Ohio), LigaSure V and the prototype Trissector. In vivo vessel diameter ...
W?lfle Stephanie E - - 2007
Intercellular communication through gap junctions coordinates vascular tone by the conduction of vasomotor responses along the vessel wall. Gap junctions in arterioles are composed of different connexins (Cxs) (Cx40, Cx37, Cx45, Cx43), but it is unknown whether Cxs are interchangeable. We used mice with a targeted replacement of Cx40 by ...
Auer M - - 2008
The assessment of morphologic changes in atherosclerotic lesions during interventional procedures such as transluminal balloon angioplasty is an issue of highest clinical importance. We propose a methodology that allows realistic 3D morphomechanical modeling of the vessel, the plaque and the lumen at different stages of in vitro angioplasty. We elaborate ...
Hemminki Virpi - - 2007
It has been suggested that asymmetric dimethylarginine (ADMA), an endogenous nitric oxide synthase inhibitor, is linked to hypertension and vascular reactivity. Retinal arteriolar narrowing has been observed to associate early with increased risk of hypertension. The objective of this study was to evaluate the role of ADMA as a biomarker ...
Miño N - - 2008
The purpose of this study was to evaluate the effects of medetomidine administration on the Doppler variables of abdominal arteries. The study population consisted of 20 healthy dogs. The haemodynamic effects of the medetomidine were defined using Doppler variables of the abdominal aorta, renal arteries, cranial mesenteric artery and celiac ...
Liu Yi - - 2007
The stress and strain in the vessel wall are important determinants of vascular physiology and pathophysiology. Vessels are constrained radially by the surrounding tissue. The hypothesis in this work is that the surrounding tissue takes up a considerable portion of the intravascular pressure and significantly reduces the wall strain and ...
Walker Kathryn L - - 2007
We tested the hypothesis that vasoregulatory mechanisms completely counteract the effects of sudden changes in arterial perfusion pressure on exercising muscle blood flow. Twelve healthy young subjects (7 female, 5 male) lay supine and performed rhythmic isometric handgrip contractions (2 s contraction/ 2 s relaxation 30% maximal voluntary contraction). Forearm ...
Harazny Joanna M - - 2007
Arterial hypertension is a major risk factor for stroke, and retinal vessels can be regarded as a mirror of the cerebral vasculature. Whether vascular remodeling of retinal arterioles with ageing and hypertension plays a role in cerebrovascular risk stratification has not yet been adequately addressed. In study 1, retinal arteriolar ...
Alnaes Martin Sandve - - 2007
BACKGROUND AND PURPOSE: Wall shear stress (WSS) and pressure are important factors in the development of cerebral aneurysms. We aimed to develop a computational fluid dynamics simulator for flow in the complete circle of Willis to study the impact of variations in vessel radii and bifurcation angles on WSS and ...
Lee Jin W - - 2007
It is shown in this paper that the nearly constant length-to-diameter ratio observed with conducting airways of human bronchial tree can be explained based on the fluid dynamic optimality principle. In any branched tube there are two pressure loss mechanisms, one for wall friction in the tube section and the ...
Albinsson Sebastian - - 2007
Caveolin-1 (Cav-1) is essential for the morphology of membrane caveolae and exerts a negative influence on a number of signaling systems, including nitric oxide (NO) production and activity of the MAP kinase cascade. In the vascular system, ablation of caveolin-1 may thus be expected to cause arterial dilatation and increased ...
Santelices L C - - 2007
While vascular stiffness is universally studied using pulse wave velocity, this method overestimates the stiffness of small calibre blood vessels. We have developed and rigorously validated an ex vivo system for measuring stiffness of the mouse aorta. The system consists of a temperature-controlled tissue bath, a pressurization loop and a ...
Ivanov K P - - 2007
Blood pressure in the circle of Willis in rats decreased to about 40 mmHg after ligation of both carotid arteries. Developing ischemia was accompanied by massive adhesion of leukocytes to the walls of brain venules and the smallest veins. Blood pressure in the vessels of the circle of Willis decreased ...
Kingwell Bronwyn - - 2007
1. Arterial stiffness, which has independent predictive value for cardiovascular events, seems to have a genetic component, largely independent of the influence of blood pressure and other cardiovascular risk factors. 2. In animal models of essential hypertension (stroke-prone spontaneously hypertensive rats and spontaneously hypertensive rats), structural modifications of the arterial ...
Lee Hyang Ae - - 2007
The mechanosensitive nonselective cation channel (NSC(MS)) and endothelin-1 (ET-1) play critical roles in the regulation of vascular tone. This study was undertaken to investigate the effect of ET-1 on NSC(MS) and on the myogenic response of arteries. Cell-attached patch-clamp techniques were applied to rabbit pulmonary and cerebral arterial smooth muscle ...
Charles Shelton M - - 2007
Although postnatal maturation potently modulates agonist-induced cerebrovascular contractility, its effects on the mechanisms mediating cerebrovascular myogenic tone remain poorly understood. Because the regulation of calcium influx and myofilament calcium sensitivity change markedly during early postnatal life, the present study tested the general hypothesis that early postnatal maturation increases the pressure ...
Dales Robert - - 2007
OBJECTIVE: Particulate air pollution is associated with cardiovascular morbidity but mechanisms are not well understood. We tested the effects on vascular reactivity of exposure to fine particulates matter mass (PM(2.5)), number of particles <or=1 microm/m(3) (PM(1.0)) and nitrogen dioxide concentration (NO(2)). METHOD: About 39 healthy volunteers sat outside for 2 ...
Rajbabu K - - 2007
INTRODUCTION: The aim of this study was to carry out an independent evaluation of the efficacy and security of a number of vessel ligation devices and ligatures. MATERIALS AND METHODS: A vascular ligation model was devised using fresh, ex vivo porcine internal carotid arteries of varying external diameters. Coloured normal ...
Jeppesen Peter - - 2007
PURPOSE: To study retinal response in terms of arteriole diameter and retinal thickness secondary to an increase in arterial blood pressure during acute hyperglycaemia. METHODS: In a randomized, double-blinded, cross-over study, nine healthy persons were subjected to clamping of blood glucose to either 5 mmol/l or 15 mmol/l using somatostatin ...
Wallwiener Christian - - 2007
OBJECTIVE: To compare the efficacy of conventional pulsed coagulation (CPC) and newly developed intelligent, impedance-regulated, pulsed coagulation (IPC) in the sealing of porcine renal arteries. DESIGN: Prospective, randomized experimental study. SETTING: Isolated porcine artery model in an academic research environment. ANIMAL(S): Female Swabian Hall pigs. INTERVENTION(S): Renal arteries were harvested ...
Dineley Judith A - - 2007
An investigation was made into the effect of acquisition parameters on the distension waveform estimated from tissue Doppler imaging (TDI). Physiological distension waveforms were generated using a compliant wall phantom. Distensions derived over a range of scanning geometries and transducer pressures were compared with those obtained in optimised scanning conditions. ...
Scarcello Edoardo - - 2007
This study reports the development of a new open external vascular stent: the lock stent device (LSD). It enables a novel end-to-end sleeve anastomotic technique, named locked anastomosis (LA). The LA technique consists of inserting a graft sleeve within an artery, secured in place by an internal stent and an ...
Webb Antonio R - - 2007
The influence of scaffold compliance on blood vessel tissue engineering remains unclear and compliance mismatch issues are important to an in vivo tissue-engineering approach. We have designed and constructed a modular bioreactor system that is capable of imparting pulsatile fluid flow while simultaneously measuring vessel distension with fluid pressure changes ...
Mansberger Steven L - - 2007
OBJECTIVE To compare the intraocular pressure (IOP) responses of self-identified African American and white participants in the Ocular Hypertension Treatment Study to therapeutic trials of topical, nonselective β-adrenergic antagonists or prostaglandin analogues. METHODS Multivariate models that adjusted for baseline IOP and corneal thickness were used to estimate IOP response by ...
Raffai G - - 2008
Previously, increased diameter and enhanced myogenic tone were seen after 2-week 45o head-up (HUT2) in the rat. We studied the reversibility and the effect of extended tilt on this phenomenon using two experimental groups: HUT2 plus 2-week horizontal (HUT2HOR2), and 4-week tilting (HUT4). 4-weeks in normal cages (NC4) served as ...
Izzo Ivano - - 2007
The paper presents an innovative fluidic microdevice for in-vitro isotonic measurements of microvessel contraction/dilation. The proposed microdevice is based on the well-known fluid dynamic principle which correlates a geometrical change of a solid body immersed in a constant flow, with the differential pressure change induced in the flow itself. Indeed, ...
Franco Walfre - - 2007
BACKGROUND AND OBJECTIVES: Application of local vacuum pressure to human skin during laser irradiation results in less absorption in the epidermis and more light delivered to targeted vessels with an increased blood volume. The objective of the present numerical study is to assess the effect of applying local vacuum pressure ...
Fonck E - - 2007
Arteries display a nonlinear anisotropic behavior dictated by the elastic properties and structural arrangement of its main constituents, elastin, collagen, and vascular smooth muscle. Elastin provides for structural integrity and for the compliance of the vessel at low pressure, whereas collagen gives the tensile resistance required at high pressures. Based ...
Lacin Tunc - - 2007
OBJECTIVE: LigaSure (Valleylab, Tyco Healthcare, Boulder, CO) is a novel instrument with widespread use in various surgical disciplines for vessel sealing. It uses heat energy to denature collagen and elastin and achieve vessel sealing. We investigated the safety of LigaSure in pulmonary arteries (PA) and veins (PV). METHODS: Twelve sheep ...
Lu Xiao - - 2007
The vasoactivity of blood vessel is impaired by cardiovascular disease. The ex-vivo measurements of vasoactivity (wire and pressure myographs) have some inherent difficulties in the characterization of pharmacodynamics and biomechanics. Here, we introduce a novel isovolumic myograph which allows simultaneous measurement of both dynamic pressure and dimensional changes during vasoconstriction ...
Hassanain Hamdy H - - 2007
Reactive oxygen species, including superoxide, are important mediators of the pathophysiology of hypertension. In the vasculature, superoxide antagonizes nitric oxide (NO*), resulting in increased vascular tone. The GTP binding protein Rac regulates a wide variety of cellular functions, including the activation of NADPH oxidase, the major source of O2*-in the ...
Rajesh Ramesh - - 2007
The relationship between the pressure inside a cylindrical mock vessel and the change in radius is called radial compliance. It has been postulated that it is the internal change in radius with pressure that has a significant effect on blood flow disturbance or the interaction of a graft or synthetic ...
Ching S S - - 2007
BACKGROUND: Torsional mode ultrasonic coagulating shears have recently been developed for endoscopic and conventional surgery. The current investigation was conducted to compare the effectiveness of this device with the more established linear mode shears for the sealing of medium- to large-sized arteries. METHODS: Porcine carotid arteries were prepared in vitro. ...
Tahvanainen Anna - - 2006
Essential hypertension is associated with several alterations in arterial function. A wealth of information from animal models is available concerning hypertensive changes in the mesenteric circulation, while only few studies have examined human mesenteric arterial function. The tone of isolated mesenteric arterial segments (outer diameter 0.7-0.9 mm) was examined from ...
Dubroca Caroline - - 2007
OBJECTIVE: Myogenic tone, which has a major role in the regulation of local blood flow, refers to the ability of vascular smooth muscle to adapt its contractility to changes in transmural pressure. Although Rho-kinase is involved in myogenic tone, the pathway involved remains unclear, especially concerning translocation to the plasma ...
Schmitz Nele - - 2006
Although mangroves have been extensively studied, little is known about their ecological wood anatomy. This investigation examined the potential use of vessel density as a proxy for soil water salinity in the mangrove species Rhizophora mucronata (Rhizophoraceae) from Kenya. In a time-standardized approach, 50 wood discs from trees growing in ...
Latorre-Moratalla M L - - 2007
The application of high hydrostatic pressure (200MPa) to meat batter just before sausage fermentation and the inoculation of starter culture were studied to improve the safety and quality of traditional Spanish fermented sausages (fuet and chorizo). Higher amounts of biogenic amines were formed in chorizo than in fuet. Without interfering ...
Hayashi Kozaburo - - 2007
To study arterial remodeling in response to hypertension, Deoxycortico-sterone acetate (DOCA)-salt hypertension was induced in immature (aged 16 weeks) and middle-aged (48 weeks) rats, and biomechanical properties and wall dimensions of common carotid arteries were determined. Arterial segments were excised at 10 or 16 weeks postoperatively from the immature rats ...
Lanzarone E - - 2007
Peripheral vasomotion, interstitial liquid exchange, and cardiovascular system behaviour are investigated by means of a lumped parameter model of the systemic and peripheral circulation, from the aortic valve to the venules. This modelling work aims at combining arterial tree hemodynamics description, active peripheral flow regulation, and fluid exchange. The arterial ...
Qin Shengping - - 2006
The existing models of the dynamics of ultrasound contrast agents (UCAs) have largely been focused on an UCA surrounded by an infinite liquid. Preliminary investigations of a microbubble's oscillation in a rigid tube have been performed using linear perturbation, under the assumption that the tube diameter is significantly larger than ...
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