Search Results
Results 451 - 500 of 1559
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Kim Kang - - 2004
Peripheral vascular strain imaging has limited strain dynamic range because arterial wall deformations only exhibit small strains under physiologic pressures. A noninvasive freehand ultrasound (US) scanning procedure was performed to apply external force, comparable to the force generated in measuring a subject's blood pressure, to achieve higher strains by equalizing ...
Vucetic M - - 2004
To quantify retinal vascular change during and after hyperbaric oxygenation (HO) for 6x5 weekly 90 minute treatments. Fundus photographs were taken before, during, and after HO at 2.5 atmospheres absolute pressure (ATA) on days 1, 2, 3, 10, 20, 29, and 30 of treatment on three patients using a specially ...
Lott Mary E J - - 2004
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 aging impairs the myogenic response. The purpose of this study was to compare the effects of changes in transmural pressure on mean ...
Geary Greg G - - 2004
We have shown recently that development from neonatal to adult life affects cerebrovascular tone of mouse cerebral arteries through endothelium-derived vasodilatory mechanisms. The current study tested the hypothesis that development from fetal to adult life affects cerebral artery vascular smooth muscle (VSM) [Ca(2+)](i) sensitivity and tone through a mechanism partially ...
de los Arcos L Rivera - - 2004
PURPOSE: We developed an in vitro method that allows us to study the physiopharmacological responses of penile resistance arteries under isobaric conditions. MATERIALS AND METHODS: Second to third order penile resistance arteries (internal diameter 170 to 210 microm) were mounted in a pressure myograph and cannulated at each end with ...
New David I - - 2004
BACKGROUND: Structural remodeling of the resistance vasculature is present in many forms of human and experimental hypertension. In particular, an increase in the ratio of wall thickness to lumen diameter develops, and might in itself maintain hypertension by increasing vascular resistance. Because uremia is associated with raised peripheral resistance, hypertension, ...
Nagel Edgar - - 2004
PURPOSE: The present study investigated whether age, blood pressure (BP), and baseline vessel diameter influence the retinal arterial response to flicker light. METHOD: Thirty healthy subjects (mean age, 46.3; range, 22-73 years) and 15 patients with untreated essential arterial hypertension (mean, 50.9; range, 26-69 years) were examined. The diameter of ...
El-Hakim A - - 2004
BACKGROUND: Two sizes of endoscopic gastrointestinal anastomosis (Endo-GIA) staples are currently available for vascular control. The purpose of this study was to compare the Endo-GIA 30-2.0 mm with the Endo-GIA 30-2.5 mm vascular staple. METHODS: The renal blood vessels, aorta, and vena cava were divided laparoscopically using the Endo-GIA 30-2.0 ...
Puyó A M - - 2004
1. A fructose (Fru)-enriched diet induces a mild increase in blood pressure associated with hyperglycaemia, hypertriglyceridaemia, and insulin resistance, resembling the human 'syndrome X', being an useful model to study hypertension and type 2 diabetes. 2. A sustained elevation of blood pressure is associated with cardiovascular structural modifications such as ...
Matthiessen E T - - 2004
BACKGROUND: It is taken for granted that glaucomatous damage is caused by changed haemodynamics of the retrobulbar vessel system besides other factors such as, for example, an elevated intraocular pressure. This was proven by various studies in which glaucoma patients were shown to have a changed retrobulbar blood flow velocity. ...
Bai Ni - - 2004
The routine availability of murine models of various cerebral circulatory disorders requires characterization of the regulation of cerebral artery tone in the mouse. Using vasoconstrictors and vasodilators with known efficacy in the cranial circulation of other species, we determined the pharmacological properties of the isolated pressurized mouse middle cerebral artery ...
Alderson H - - 2004
The placement of a rigid stent within an elastic vessel produces wave reflection sites at the entrance to and exit from the stent. The net haemodynamic effects of these reflections depend critically on the degree of stiffness of the stent and on its length and position within the diseased vessel, ...
Bakker Erik N T P - - 2004
Remodeling of resistance arteries is a key feature in hypertension. We studied the transition of vasoconstriction to remodeling in isolated rat skeletal muscle arterioles. Arterioles activated with 10 nM endothelin-1 showed functional adaptation when kept at low distension in a wire myograph setup, where contractile properties shifted towards a smaller ...
Rizzoni Damiano - - 2004
Structural alterations of small resistance arteries in patients with essential hypertension (EH) are mostly characterized by inward eutrophic remodeling. However, we have observed the presence of hypertrophic remodeling in patients with renovascular hypertension, as well as in patients with noninsulin-dependent diabetes mellitus, suggesting a relevant effect of humoral growth factors ...
Elhadj Selim - - 2004
The determination of the mechanical properties of vascular growth substrates has seen increasing interest in the bioengineering field. Mechanical features such as rupture strength, compliance characteristics, and viscoelastic properties of vascular grafts are important for their design and are indicative of their success in vivo. Thus a simple inexpensive measurement ...
Wong Tien Yin - - 2004
BACKGROUND: Narrowing of the small arterioles has been hypothesized to contribute to the pathogenesis of hypertension, but prospective clinical data are lacking. OBJECTIVE: To examine the relation of retinal arteriolar narrowing to incident hypertension in healthy middle-aged persons. DESIGN: Prospective cohort study. SETTING: The population-based Atherosclerosis Risk in Communities Study, ...
Lehoux Stéphanie - - 2004
BACKGROUND: High blood pressure causes a change in vascular wall structure involving altered extracellular matrix composition, but how this process occurs is not fully understood. METHODS AND RESULTS: Using mouse carotid arteries maintained in organ culture for 3 days, we detected increased gelatin zymographic activity of matrix metalloproteinase (MMP)-2 (168+/-13%, ...
Bakker Erik N T P - - 2004
The hypothesis was tested that pressure and pressure pulsation modulate vascular remodeling. Arterioles ( approximately 200 microm lumen diameter) were dissected from rat cremaster muscle and studied in organoid culture. In the first series, arterioles were kept at a stable pressure level of either 50 or 100 mmHg for 3 ...
Coulson Rebecca J - - 2004
The inner diameter and wall thickness of rat middle cerebral arteries (MCAs) were measured in vitro in both a pressure-induced, myogenically-active state and a drug-induced, passive state to quantify active and passive mechanical behavior. Elasticity parameters from the literature (stiffness derived from an exponential pressure-diameter relationship, beta, and elasticity in ...
Nakamura Motoyuki - - 2004
BACKGROUND: Alterations in elastic properties and vascular structure of conduit vessels are important detrimental factors contributing to increased cardiac load and reduced tissue perfusion in patients with congestive heart failure (CHF). It has been demonstrated that endothelial function in the peripheral vasculature is impaired in this disorder, which may induce ...
Szekeres Maria - - 2004
The myogenic response, an active constriction and dilation of vessels to changes in intravascular pressure, can play an important role in the regulation of coronary blood flow. The characteristics of the myogenic response and its modulation by endothelium-derived factors are organ and location specific and have not been studied extensively ...
Cipolla Marilyn J - - 2004
Eclampsia is thought to be similar to hypertensive encephalopathy, whereby acute elevations in intravascular pressure cause forced dilatation (FD) of intrinsic myogenic tone of cerebral arteries and arterioles, decreased cerebrovascular resistance, and hyperperfusion. In the present study, we tested the hypothesis that pregnancy and/or the postpartum period predispose cerebral arteries ...
Pessana F - - 2004
The viscoelastic properties of the arterial wall are responsible for their functional role in the arterial system. Cryopreservation is widely used to preserve blood vessels for vascular reconstruction but is controversially suspected to affect the dynamic behaviour of these allografts. The aim of this study was to determine whether differences ...
Lin Albert Chin-Yuh - - 2004
From the energy point of view, obtaining simultaneous blood pressure and flow rate of the radial artery at the wrist is very important for sphygmic diagnosis in medicine. This work depicts the conceptual design for a noninvasive multi-functional sphygmus detection system. According to Y. C. Fung's flow rate equation, flow ...
Kispélyi Barbara - - 2004
The newly developed self-etching, self-priming all-in-one adhesives are appealing to clinicians because they are simple and efficient to use. These single-application bonding systems contain chemically active compounds that can alter pulpal blood circulation when applied to deep dentin surfaces. Since adequate microcirculation and oxygenation are the basic requirements for tissue ...
Svaasand Lars O - - 2004
BACKGROUND AND OBJECTIVES: The average success rate in achieving total blanching of port wine stain (PWS) lesions treated with laser-induced selective photothermolysis is below 25%, even after multiple treatments. This is because smaller diameter (5-20 microm) PWS blood vessels are difficult to destroy with selective photothermolysis since the volumetric heat ...
Jarajapu Yagna P R - - 2004
PURPOSE: To study and quantify myogenic behavior and reactivity of the rat ophthalmic artery to pressure and different vasoactive substances in vitro. METHODS: Rat ophthalmic arteries (diameter of 217 +/- 6 microm, n = 22) were isolated, cannulated with glass pipettes in an arteriograph and pressurized in a physiological buffer. ...
Shou Y - - 2004
Atherosclerosis is a disease mainly of large, high pressure arteries and of valves, typically sparing veins and small, low pressure arteries. We investigate the resistances of the vena cava and the pulmonary artery to the flow of water and the infiltration of solutes into the vessel walls and compare them ...
Coats P - - 2003
In critical limb ischaemia (CLI), the ability to regulate regional blood flow in the diseased portion of the leg would appear to be severely compromised. Considering this, pressure-dependent myogenic and mechanical properties of resistance arterioles isolated from control subjects and from patients with CLI were studied. Using confocal microscopy and ...
Garhöfer Gerhard - - 2003
PURPOSE: Diffuse luminance flicker light increases retinal and optic nerve head blood flow in animals and humans, but the exact mechanisms that mediate increased flow have yet to be identified. In the current study, the effect of increased plasma lactate levels on flicker-induced vasodilatation in the retina was investigated in ...
Rajagopalan Sanjay - - 2003
Raynaud's syndrome (RS), which is characterized by recurrent episodes of vasospasm with exposure to cold, may occur alone (primary RS) or in association with connective tissue diseases or other underlying conditions (secondary RS). We investigated the effect of cilostazol on vessel wall responses in RS. Patients were diagnosed (primary or ...
Nagel Edgar - - 2004
PURPOSE: To investigate the autoregulative response of large retinal vessels to artificial reduction of perfusion pressure. METHODS: The diameters of a venous and an arterial segment (each approx.1.5 mm in length) in one eye of each of 13 healthy volunteers (age 54.5+/-18 years) were measured continuously using the Retinal Vessel ...
Moosmang Sven - - 2003
Blood pressure is regulated by a number of key molecules involving G-protein-coupled receptors, ion channels and monomeric small G-proteins. The relative contribution of these different signaling pathways to blood pressure regulation remains to be determined. Tamoxifen-induced, smooth muscle-specific inactivation of the L-type Cav1.2 Ca2+ channel gene in mice (SMAKO) reduced ...
Rumbaugh Marilyn L - - 2003
To compare arterial bursting pressure after vessel closure using a vessel-sealing device (LigaSure Atlas Laparoscopic Sealer/Divider Instrument; Valleylab, Boulder, CO), a ligate-and-divide stapling device (LDS), and 2-0 polydioxanone suture. To evaluate the LigaSure Atlas as a method for ligation of the mesenteric vasculature during small intestinal resection in normal horses. ...
Jacobsen Jens Christian Brings - - 2003
Adequate function of the microcirculation is vital to any tissue. To maintain an optimal function, microvascular networks must be able to adapt structurally to changes in the physical environment. Here we present a mathematical network model based on vessel wall mechanics. We assume based on experimental observations that longstanding change ...
D'Armiento Jeanine - - 2003
Mice haploinsufficient for elastin develop structural changes in vessel walls similar to those seen in patients with mutations in the elastin gene. A new study demonstrates that due to mechanical changes in the vessel wall, these animals exhibit increased mean arterial pressures. The results evoke the possibility that alterations in ...
Gokina Natalia I - - 2003
OBJECTIVES: The objectives of this study were to investigate differences in diameter and vasoconstriction of premyometrial versus uteroplacental radial arteries and to evaluate the contribution of nitric oxide (NO) to myogenic tone as a function of vessel location. STUDY DESIGN: Radial arteries supplying either the myometrium or placenta were dissected ...
Presthus James B - - 2003
We evaluated the vessel-sealing ability of one application of a pulsed plasma kinetic (PK) electrosurgical device on skeletonized vessels up to 7 mm in diameter to withstand sustained pressure of 300 mm Hg using bench and animal models. Forty-six porcine specimens and 66 abattoir vessels (112 total) were pressure tested ...
Perrée Jop - - 2003
In this report we describe the application of an in vitro pressure-perfusion system for study of functional/structural changes after in vitro balloon dilation injury. Pig carotid arteries were perfused at P = 100 mm Hg and Q = 100 ml/min, balloon angioplastied (BA), and cultured under these hemodynamic conditions for ...
Shiraishi Mitsuya - - 2003
The physiological role of smooth muscle myosin heavy chain (MHC) isoform diversity is poorly understood. The expression of MHC-B, which contains an insert at the ATP binding pocket, has been linked to enhanced contractile kinetics. We recently reported that the renal afferent arteriole exhibits an unusually rapid myogenic response and ...
Rohra Dileep Kumar - - 2003
Hydrogen ion concentration (H+) is an important regulator of many cellular functions including contractility of the vascular smooth muscle cells. In many physiological and pathological states, changes in pH may have profound effects on the contractility of blood vessels and thus on the peripheral vascular resistance and blood pressure. Therefore, ...
Vicaut E - - 2003
A large part of the changes in peripheral resistances associated with hypertension involves changes in the microvascular network. From the brief review presented here, it appears that arterioles' functional characteristics are largely modified in hypertension. Sensitivity to numerous vasoconstrictive substances is increased. Local angiotensin-converting enzyme activity is considerably higher. Endothelium-dependent ...
Undavia Samir S - - 2003
Previous in vivo studies indicate that vascular autoregulation does take place in adipose tissue. We tested the hypothesis that adipose tissue arterioles can develop a myogenic response to increases in transmural pressure. Arterioles, isolated from the inguinal fat pad of male Wistar rats, were placed in a microvessel chamber containing ...
Tamura N - - 2003
In situ tissue engineering using acellular xenografts is a new approach to autologous tissue regeneration. In the present study, we analyzed a new regeneration scaffold comprised of xenogenic acellular vessels in a dog model. Xenogenic vascular conduits of porcine carotid arteries were acellularized by a 48-hour detergent incubation to extract ...
Wang Jie Jin - - 2003
To describe cross-sectional relations between hypertension and retinal vessel wall signs in an older white population. These signs were defined from fundus photographs in 3654 Blue Mountains Eye Study participants > or =49 years of age. Focal arteriolar narrowing and arteriovenous nicking were graded through the use of standard protocol. ...
Tozzi P - - 2003
A high resolution echo-tracking system permits the calculation of cross-sectional compliance considering vessel diameter variations alone, and assumes that longitudinal movement of the vessel wall due to pulse pressure is negligible. However, using piezoelectric crystals sutured on the adventitia of the vessel wall we demonstrated that arterial length changes up ...
Brook Robert D - - 2003
OBJECTIVE: We sought to determine if hypertensive adults have a blunted triglyceride catabolic rate (TG K(2)) and if related hemodynamic and vascular alterations are determinants of TG K(2). METHODS: Fasting levels of insulin, glucose, lipoproteins and plasma catecholamines were measured in 10 normotensive and 10 hypertensive adults. TG K(2) was ...
Lemarié Catherine A - - 2003
The effects of mechanical factors on nuclear factor (NF)-kappaB activation and its potential functional roles have been very little explored in the intact vessel. Thus, we chose to study the regulation of NF-kappaB by intraluminal pressure using an organ culture model of mouse carotid arteries maintained at 80 or 150 ...
Vlasova M A - - 2003
Clipping of the abdominal aorta distally to the renal arteries produces a persistent decrease in blood pressure in hindquarter vessels by 35-40%. On week 6-7 postoperation, the reactions of the caudal artery perfused in vitro under constant pressure to norepinephrine were studied. At transmural pressure of 150 mm Hg, the ...
Leung Harry - - 2003
PURPOSE: To describe the cross-sectional relationships between age, blood pressure (BP), and quantitative measures of retinal vessel diameters in an older Australian population. METHODS: Retinal photographs from right eyes of participants (n = 3654, aged 49+ years) in the Blue Mountains Eye study taken during baseline examinations (1992-1994) were digitized. ...
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