Search Results
Results 351 - 400 of 1589
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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 S Department of Biomedical Engineering, University of California, Davis, CA 95616, USA. - - 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 ...
Westerhof Berend E - - 2007
We investigated the quantitative contribution of all local conduit arterial, blood, and distal load properties to the pressure transfer function from brachial artery to aorta. The model was based on anatomical data, Young's modulus, wall viscosity, blood viscosity, and blood density. A three-element windkessel represented the distal arterial tree. Sensitivity ...
Lott Mary E J - - 2007
The myogenic response, the inherent ability of blood vessels to rapidly respond to changes in transmural pressure, is involved in local blood flow autoregulation. Animal studies suggest that both acute hyperglycemia and hyperinsulinemia may impair myogenic vasoconstriction. The purpose of this study was to examine the effects of an oral ...
Ito Isamu - - 2007
The pressure-induced constriction in the rat ophthalmic artery was characterized. Ophthalmic arteries were isolated, cannulated in an arteriograph, and pressurized. Arteries developed 25% constriction at 70 mmHg of intraluminal pressure. Arteries maintained almost similar diameter over the range of pressures 50-210 mmHg, and forced dilatation was observed at pressures >210 ...
Pose-Reino Antonio - - 2006
Evaluation of early hypertension-related alterations in retinal microcirculation has been subjective and poorly reproducible. The authors recently described a semiautomatic computerized system for evaluation of the calibre of retinal blood vessels that has shown very good reproducibility. In the study, this system was used to measure the calibres of retinal ...
Mourad Jean-Jacques - - 2006
Structural alterations in the microcirculation form a major link between hypertension and target organ damage. More than 60% of the overall peripheral resistance of the circulatory system arises at the level of the microcirculation. The primary function of the microcirculation is to supply oxygen and nutrients to tissues. In hypertension, ...
Taarnhøj Nina C B B - - 2006
PURPOSE: To assess the relative influence of genetic and environmental effects on retinal vessel diameters and blood pressure in healthy adults, as well as the possible genetic connection between these two characteristics. METHODS: In 55 monozygotic and 50 dizygotic same-sex healthy twin pairs, aged 20 to 46 years, interpolated diameter ...
Takeda Satoru - - 2006
Myogenic tone is intrinsic to vascular tissue and plays an important role in determining basal coronary resistance. However, the effect of the beating heart on myogenic tone is unknown. We investigated the effects of myocardium-derived vasoactive factors on the myogenic tone of coronary microvessels in the resting condition and during ...
Qin Shengping - - 2006
This paper presents a detailed study of the oscillation characteristics of a bubble confined inside a deformable microvessel, whose size is comparable with the bubble size. The vessel's compliance is characterized by a nonlinear relation between the intraluminal pressure and the expansion ratio of the vessel radius, which represents the ...
Nagel E - - 2006
PURPOSE: The study examined the influence of individual blood pressure changes overtime on retinal vessel diameter and the latter's response to flicker light. METHODS: The diameter of a retinal arterial and venous segment was measured continuously on-line with a Dynamic Vessel Analyzer in 20 patients twice (mean interval between examinations ...
Razus Domnina - - 2007
The maximum rates of pressure rise of propylene-air explosions at various initial pressures and various fuel/oxygen ratios in three closed vessels (a spherical vessel with central ignition and two cylindrical vessels with central or with top ignition) are reported. It was found that in explosions of quiescent mixtures the maximum ...
Gleason Rudolph L - - 2007
Many have studied the roles of altered blood flow and pressure on adaptive responses of blood vessels, but few have studied the role of altered axial loads. We exposed common carotid arteries from wild-type mice to low, medium, or high axial extensions while maintaining the same pressure and luminal flow ...
Koenigsberger Michèle - - 2006
Smooth muscle and endothelial cells in the arterial wall are exposed to mechanical stress. Indeed blood flow induces intraluminal pressure variations and shear stress. An increase in pressure may induce a vessel contraction, a phenomenon known as the myogenic response. Many muscular vessels present vasomotion, i.e., rhythmic diameter oscillations caused ...
Kanu Alie A Dept. of Physiology, Univ. of Tennessee Health Science Center, 894 Union Ave, Memphis, TN 38163, - - 2006
The gaseous compound carbon monoxide (CO) has been identified as an important endogenous biological messenger in brain and is a major component in regulation of cerebrovascular circulation in newborns. CO is produced endogenously by catabolism of heme to CO, free iron, and biliverdin during enzymatic degradation of heme by heme ...
Chen Tim T - - 2006
Small arteries play an essential role in the regulation of blood pressure and organ-specific blood flow by contracting in response to increased intraluminal pressure, ie, the myogenic response. The molecular basis of the myogenic response remains to be defined. To achieve incremental changes in arterial diameter, as well as blood ...
Salameh Jihad R - - 2006
BACKGROUND: The LigaSure system (Valleylab, Boulder, CO) seals vessels by reforming collagen and elastin in vessel walls. We studied the feasibility and effectiveness of LigaSure in dividing porcine small bowel. METHODS: Twelve porcine small bowel portions were randomized to division with either endoscopic linear stapler or LigaSure system and the ...
Shou Yixin - - 2006
In this study, filtration flows through the walls of the rat aorta, pulmonary artery (PA), and inferior vena cava (IVC), vessels with very different susceptibilities to atherosclerosis, were measured as a function of transmural pressure (DeltaP), with intact and denuded endothelium on the same vessel. Aortic hydraulic conductivity (L(p)) is ...
Call Christopher - - 2006
We recently determined that the ability of the femoral artery (FA) to maintain higher levels of tonic isometric stress compared with the saphenous artery (SA) was due to differential expression of motor proteins permitting latch-bridge formation in FA and not SA. Arteries under pressure in vivo are not constrained to ...
Thakrar Raj R - - 2006
Assess the effects of cryopreservation (cryo) and vitrification (vitro) on the viscoelastic properties of blood vessels. Human external Iliac artery vessels were harvested from liver organ donors (n=8). In each case the vessel was segmented into 3 equal parts, which were randomly placed in one of 3 categories: Fresh (stored ...
Moreno de Sandino M - - 2006
Lung samples from 30 pulmonary hypertensive chickens expressing low nitric oxide (NO) synthase activity in endothelial arteriolar cells were compared with samples taken from 30 nonhypertensive animals expressing high activity to investigate a possible relationship between the just-mentioned expressions and pulmonary vascular remodeling. The external diameter and media muscular thickness ...
Sorop Oana - - 2006
The capacity for myocardial perfusion depends on the structure of the coronary microvascular bed. Coronary microvessels may adapt their structure to various stimuli. We tested whether the local pressure profile affects tone and remodeling of porcine coronary microvessels. Subendocardial vessels (approximately 160 microm, n=53) were cannulated and kept in organoid ...
Ivert Lena - - 2006
BACKGROUND: To investigate how transient pressure applied to the retinal pigment epithelium (RPE) layer and choroid affects choroidal blood flow in rabbits. METHODS: Twelve rabbits underwent vitrectomy and local retinectomy. In nine of the rabbits a glass rod was used to exert brief pressure on the RPE layer and choroid. ...
Juhl Louise - - 2006
Adrenomedullin is related to the calcitonin gene-related peptide (CGRP) family and is present in cerebral blood vessels. It may be involved in migraine mechanisms. We measured the change in dural and pial artery diameter, mean arterial blood pressure and local cerebral blood flow flux (LCBF(Flux)) after intravenous (i.v.) infusion of ...
Sivarajan Vivek - - 2007
The assessment of capillary vascular malformation (CM) morphology can be performed using videomicroscopy. Previously only the type of capillary pattern could be demonstrated. The Depth Measurement Videomicroscope (DMV) allows both depth and diameter of CM vessels to be measured. The aim of this study was to examine how videomicroscope recordings ...
Weigert Günther - - 2006
PURPOSE: Intravenous administration of histamine causes an increase in choroidal blood flow (ChBF) and retinal vessel diameters in healthy subjects. The receptor mediating this response has not yet been identified. The present study was undertaken to clarify whether H1 receptor blockade with diphenhydramine affects the hemodynamic response of histamine in ...
Szekeres M - - 2006
Interactions between the biomechanical characteristics and pressure-induced active response of coronary microvessels are still not well known. We tested the hypothesis that pressure-dependent biomechanical characteristics of the coronary vascular wall are modulated by the active myogenic response and local vasodilators. We have utilized data obtained previously in isolated rat intramural ...
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