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Results 351 - 400 of 1567
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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 ...
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 ...
Kanu Alie - - 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 ...
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 ...
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 ...
Clifford Philip S - - 2006
To date, no satisfactory explanation has been provided for the immediate increase in blood flow to skeletal muscles at the onset of exercise. We hypothesized that rapid vasodilatation is a consequence of release of a vasoactive substance from the endothelium owing to mechanical deformation of the vasculature during contraction. Rat ...
Rosa Robert H RH - - 2006
Brimonidine, an alpha2-adrenergic receptor (AR) agonist, has been employed in the treatment of glaucoma due to its beneficial effects on intraocular pressure reduction and neuroprotection. In addition, some studies have implicated that brimonidine might influence ocular blood flow; however, its effect on the retinal microcirculation has not been documented. Herein, ...
Armentano Ricardo L - - 2006
Damping is the conversion of mechanical energy of a structure into thermal energy, and it is related to the material viscous behavior. To evaluate the role of damping in the common carotid artery (CCA) wall in human hypertension and the possible improvement of angiotensin-converting enzyme (ACE) inhibition, we used noninvasive ...
Maneen Matthew J - - 2006
BACKGROUND AND PURPOSE: This study investigated the effect of peroxynitrite (ONOO-) on pressure-induced myogenic activity and vascular smooth muscle (VSM) actin of isolated posterior cerebral arteries (PCAs). METHODS: Histochemical staining of nitrotyrosine (NT) was used to demonstrate the presence of ONOO- in the cerebrovasculature after 1 hour of middle cerebral ...
Razus Domnina - - 2006
An experimental study on pressure evolution during closed vessel explosions of several gaseous fuel-air mixtures was performed, at various initial pressures within 0.3-1.2 bar and ambient initial temperature. Explosion pressures and explosion times are reported for methane-, n-pentane-, n-hexane-, propene-, butene-, butadiene-, cyclohexane- and benzene-air mixtures. The explosion pressures measured ...
Xiao Daliao - - 2006
The mechanisms of adaptation of uterine artery vascular tone to pregnancy are not fully understood. The present study tested the hypothesis that pregnancy decreases the PKC-mediated Ca(2+) sensitivity of the contractile process and attenuates myogenic tone in resistance-sized uterine arteries. In pressurized uterine arteries from nonpregnant (NPUA) and near-term pregnant ...
Smith Ronald D - - 2006
The VIOS (Vascular Improvement with Olmesartan medoxomil Study) study is a randomized, parallel study to determine the relative effects of suppressing the renin-angiotensin system (RAS) with the angiotensin receptor antagonist olmesartan medoxomil versus suppressing sympathetic drive with the beta-adrenoceptor antagonist atenolol on remodeling of the subcutaneous small resistance vessel. Remodeling ...
Triboulet Jean J Univ. of Montpellier II. - - 2006
This paper deals with the influence of the echographic probe pressure on the measurement of arterial diameter. It is common sense that arterial diameter measurements are affected by the pressure exerted on the B-mode ultrasound probe but we found no report in the current literature analyzing and quantifying this effect. ...
Heerkens Egidius H J - - 2006
Human essential hypertension is characterized by eutrophic remodeling of small arteries, with little evidence of hypertrophy. Likewise, vessels of young hypertensive TGR(mRen2)27 animals have undergone similar structural alterations. The role of integrins in resistance arteries of TGR(mRen2)27 during the eutrophic-remodeling process was examined as blood pressure rose. Initially, 8 alpha ...
Risler Norma R - - 2005
The basic hemodynamic abnormality in hypertension is an increased peripheral resistance that is due mainly to a decreased vascular lumen derived from structural changes in the small arteries wall, named (as a whole) vascular remodeling. The vascular wall is an active, flexible, and integrated organ made up of cellular (endothelial ...
Gleason Rudolph L RL - - 2005
Soft tissue growth and remodelling (G&R) are achieved through highly complex, temporally regulated mechanisms that lead to the adaptation of structurally significant cells and extracellular matrix proteins. Herein we present a constrained mixture model to describe vascular adaptations in response to large perturbations in luminal flow rate, transmural pressure and ...
Goto Hirohisa - - 2005
A general formula (Oka and Azuma's equation) has been rigorously derived for the circumferential wall tension in a hollow cylindrical tube in equilibrium. To evaluate the validity and usefulness of Oka and Azuma's equation, T = P(1) x r(1) - P(2) x r(2) (T, circumferential wall tension; P(1) and P(2), ...
Auer Roland N - - 2005
We here review the pathophysiology of primary intracerebral hemorrhage to compare and contrast bleeds due to hypertension and congophilic angiopathy. Hypertension is characterized by early proliferation of arteriolar smooth muscle, followed later by apoptotic smooth muscle cell death and collagen deposition. Eventually excess or deficient collagen deposition can lead respectively ...
Sato Yoshinobu - - 2005
Scale-up of wet granulation in a vertical high shear mixer was conducted. Pharmaceutical excipient mixtures composed of lactose, cornstarch and micro-crystalline cellulose, and hydroxypropylecellulose as a binder were mixed together and then granulated with purified water under various operating conditions and vessel scales. Torque of agitator shaft was continuously measured ...
Bergh Niklas - - 2005
The vascular endothelium transduces physical stimuli within the circulation into physiological responses, which influence vascular remodelling and tissue homeostasis. Therefore, a new computerized biomechanical ex vivo perfusion system was developed, in which small intact vessels can be perfused under well-defined biomechanical forces. The system enables monitoring and regulation of vessel ...
Shi Ying - - 2006
Nonselective inhibition of nitric oxide (NO) synthase (NOS) augments myogenic autoregulation, an action that implies enhancement of pressure-induced constriction and dilatation. This pattern is not explained solely by interaction with a vasoconstrictor pathway. To test involvement of the Rho-Rho kinase pathway in modulation of autoregulation by NO, the selective Rho ...
Bagatto Brian - - 2006
There has been considerable recent interest in the development of the circulation in the zebrafish. Optical techniques typically used to visualize changes in heart size allow measurement of stroke volume during early vertebrate development, but this approach is complicated in zebrafish larvae because of the heart's irregular shape and its ...
Tangney Paul - - 2005
We used simulations with a classical force field to study the transformation under hydrostatic pressure of isolated single-walled nanotubes (SWNT) from a circular to a collapsed cross section. Small-diameter SWNTs deform continuously under pressure, whereas larger-diameter SWNTs display hysteresis and undergo a first-order-like transformation. The different behavior is due to ...
Li Yang - - 2005
We investigated the effect of relaxin on vasodilation, myogenic reactivity, and compliance of small mesenteric arteries and veins. In acute experiments, small (second order) mesenteric arteries and veins from female rats were mounted in a pressure myograph, perfused intraluminally with relaxin, and exposed to incremental increases in intraluminal pressure (20-120 ...
Gu Hai - - 2006
The slit arteriotomy for end-to-side arterial microanastomosis is a technique used to revascularize free flaps in reconstructive surgery. Does a slit open to a width sufficient for blood supply? How is the slit opening affected by factors, such as arterial wall thickness and material stiffness? To answer these questions we ...
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