Search Results
Results 451 - 500 of 1579
< 5 6 7 8 9 10 11 12 13 14 15 >
Kolkman Roy G M - - 2004
A double-ring sensor was applied in photoacoustic tomographic imaging of artificial blood vessels as well as blood vessels in a rabbit ear. The peak-to-peak time (tau(pp)) of the laser (1064 nm) induced pressure transient was used to estimate the axial vessel diameter. Comparison with the actual vessel diameter showed that ...
Rummery Nicole M - - 2004
Four connexin (Cx) molecules, namely Cx37, Cx40, Cx43 and Cx45, are expressed in the gap junctions that exist within and between the cellular layers of arteries. Endothelial cells are well coupled by large gap junctions expressing Cx37, Cx40 and, to a lesser extent, Cx43, whose expression may be more subject ...
Uspenskaia Olga - - 2004
BACKGROUND: Microvascular alterations contribute to the development of stroke and vascular dementia. The goal of this study was to evaluate age and hypertension related changes of the basal lamina in cerebral microvessels of individuals, who died from non-cerebral causes. RESULTS: We examined 27 human brains: 11 young and 16 old ...
Yang Jian - - 2004
Experimental and diagnostic procedures like distension of a balloon catheter, bougie, and esophagogastroduodenoscopy can induce shear deformation in the esophageal wall. However, the shear modulus of the esophagus is yet unknown. The aim of this study was to determine the esophageal shear modulus and its dependence on the circumferential and ...
De Leeuw F-E - - 2004
BACKGROUND: Vascular risk factors could play a role in the aetiology of Alzheimer's disease, but this has not been investigated in relation to neuroimaging findings OBJECTIVE: To evaluate the distribution of blood pressure and an indicator of atherosclerosis (pulse pressure) in patients with Alzheimer's disease with and without small vessel ...
Earley Scott - - 2004
Communication between vascular smooth muscle (VSM) cells via low-resistance gap junctions may facilitate vascular function by synchronizing the contractile state of individual cells within the vessel wall. We hypothesized that inhibition of gap junctional communication would impair constrictor responses of mesenteric resistance arteries. Immunohistochemical experiments revealed positive staining for connexin ...
Leung Harry - - 2004
OBJECTIVE: To examine the effects of current and past blood pressure on retinal arteriolar diameter in a general older population. DESIGN: Cross-sectional and longitudinal studies. SETTING: Population-based cohort study of older residents from an area west of Sydney, Australia. PARTICIPANTS: Two thousand three hundred and thirty-five individuals (n = 2335) ...
Li Zhuangjie - - 2004
The reversibility of tissue remodeling is of general interest to medicine. Pulmonary arterial tissue remodeling during hypertension induced by hypoxic breathing is well known, but little has been said about the recovery of the arterial wall when the blood pressure is lowered again. We hypothesize that tissue recovery is a ...
Jeppesen Peter - - 2004
PURPOSE: To study the age-dependent change in myogenic response of retinal arterioles. METHODS: Fifty-one healthy volunteers with at least ten persons in each of the five age decades (I-V) between 20 and 69 years were subjected to diameter measurement of retinal arterioles using the Retinal Vessel Analyzer (RVA) during rest ...
Stewart Sandy F C - - 2004
Small-diameter vascular graft failure by intimal hyperplasia and thrombosis may result from flow disturbances and disruption of chemical transport in the fluid at the distal anastomosis, because of compliance mismatch between the graft and host artery. In previous studies. lower-than-normal wall shear stress (WSS), particle trapping, and high particle residence ...
Yan Ji-Geng - - 2004
Irrigation solution is routinely used in microsurgery. While the anticoagulation solution may aid in anastomotic patency, the direct effect of pressure irrigation can have a detrimental effect on the vessel. An experimental study was performed to determine the effect of irrigation pressure on the vessel wall. Histological evaluation with hematoxylin ...
Westedt Ulrich - - 2004
Catheter-based local delivery of drug loaded nanoparticles agents offers a potential therapeutic approach to reducing restenosis. However, high delivery pressures and large volumes of infusates may cause severe vascular damage and increase intimal thickening. Therefore, we investigated the penetration pattern and vessel wall integrity of fluorescence-labelled nanoparticles (217 nm in ...
Ikram M Kamran - - 2004
PURPOSE: A lower retinal arteriolar-to-venular ratio (AVR) has been suggested to reflect generalized arteriolar narrowing and to predict the risk of cardiovascular diseases. The contribution of the separate arteriolar and venular diameters to this AVR is unknown. Thus, associations between retinal arteriolar and venular diameters, and the AVR on the ...
Eiken O - - 2004
AIM: Because of the great differences in hydrostatic pressure acting along the blood vessels in the erect posture, leg vessels are exposed to greater transmural pressures than arm vessels. The in vivo pressure-distension relationship of arteries, arterioles and veins in the arm were compared with those of the leg. METHODS: ...
Cipolla Marilyn J MJ Department of Neurology, University of Vermont, Burlington, VT 05405, USA. - - 2004
We investigated the functional heterogeneity of cerebral pial arteries that are extrinsically innervated versus penetrating brain parenchymal arterioles (PA) that are intrinsically innervated by comparing myogenic activity and reactivity to neurotransmitter. Pial middle cerebral arteries (MCA, n = 6) and PA (n = 6) that branched off the MCA and ...
Wong Tien Yin - - 2004
To examine the relation between diameters of the retinal arterioles and 10 year incidence of hypertension. Population based prospective cohort study. Beaver Dam eye study. 2451 normotensive people aged 43 to 84 years. Diameters of retinal arterioles and venules measured from digitised photographs of the retina taken at baseline. Measurements ...
Wong Tien Yin - - 2004
PURPOSE: To determine if refractive errors influence the association of blood pressure and retinal vessel diameters. DESIGN: Population-based, cross-sectional study. METHODS: Retinal photographs from the right eyes of participants (n = 3,654, aged 49+ years) in the Blue Mountains Eye Study taken during baseline examinations (1992 to 1994) were digitized. ...
McVeigh Gary E - - 2004
Alteration in the physical properties of arterial blood vessels act as the substrate for end-organ damage and the occurrence of vascular events in hypertension. Structural and functional alteration in the microcirculation represents a prevalent and characteristic abnormality described in the earliest stages of hypertension. In addition to lowering arterial pressure, ...
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 ...
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. ...
Lin Albert Chin-Yuh AC Dept. of Autom. Control Eng., Feng Chia Univ., Taichung, Taiwan, Republic of - - 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 ...
Pessana F F Universidad Favaloro, Buenos Aires, - - 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 ...
Shou Y Y Department of Chem. Engineering, CUNY, New York, NY, - - 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 ...
< 5 6 7 8 9 10 11 12 13 14 15 >