Search Results
Results 401 - 450 of 1559
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Liddell Robert P - - 2005
PURPOSE: Current animal hindlimb ischemia models involve surgical ligation of the femoral artery and delivery of therapeutic angiogenic agents into the adductor compartment. The authors hypothesize that an endovascular model of hindlimb ischemia would be a more appropriate platform, closely resembling atherosclerosis by occluding the vessel from within, causing less ...
Bagi Zsolt - - 2005
OBJECTIVE: Type 2 diabetes mellitus (T2-DM) is frequently associated with vascular dysfunction and elevated blood pressure, yet the underlying mechanisms are not completely understood. We hypothesized that in T2-DM, the regulation of peripheral vascular resistance is altered because of changes in local vasomotor mechanisms. METHODS AND RESULTS: In mice with ...
Takagi Kentaro - - 2005
The effects of electroacupuncture stimulation (EAS) of the hind paw and the back on the mesenteric microhemodynamics in anesthetized rats were investigated using an intravital microscope system. Red blood cell (RBC) velocity in the mesenteric arterioles was measured by the dual-sensor method developed by the authors. Electrical stimulation was applied ...
Petersen K A - - 2005
Calcitonin gene-related peptide (CGRP) and related peptides may be involved in migraine pathogenesis. To understand their vasomotor role in the cerebral circulation, we performed two studies, a pressurized arteriography study of the middle cerebral artery (MCA) and a genuine closed cranial window (gCCW) in vivo study. Using the pressurized arteriography ...
Hendlin Kari - - 2005
BACKGROUND AND PURPOSE: The dynamics of ureteral balloon expansion may differ with increasing extrinsic compressive forces and inflation pressures. This study compared the ability of ureteral balloons to expand under different conditions. MATERIALS AND METHODS: The balloons tested were the Cook Accent, Ascend, Ascend AQ, and Pursuit; the Bard 195503 ...
Roy Sylvain - - 2005
To analyze the effects of decellularization on the biomechanical properties of porcine common carotid arteries, decellularization was performed by a detergent-enzymatic procedure that preserves extracellular matrix scaffold. Internal diameter, external diameter, and wall thickness were measured by optical microscopy on neighboring histological sections before and after decellularization. Rupture tests were ...
Cheng Allen - - 2005
In an attempt to provide a better understanding of our finding that regions with contracting left ventricular myofibers need not develop a significant transmural systolic wall thickening gradient, the analytic approach of Costa et al. was applied to the four-dimensional dynamic data obtained 1 and 8 wk after surgical implantation ...
Jean-Louis Seendy - - 2005
PURPOSE: Several studies have investigated the changes in retinal vessel diameter during physiological stress or pathologic conditions. These studies were principally based on individual fundus photographs and as such did not allow the evaluation of vessel dynamics over time. The research objective was to detail the time course and amplitude ...
Karam Gebran N - - 2005
BACKGROUND AND AIMS: The xylem, or water transport system, in vascular plants adopts different morphologies that appear sequentially during growth phases. This paper proposes an explanation of these morphologies based on engineering design principles. METHODS: Using microscopic observations of the different growth stages, an engineering analysis of the xylem vessels ...
Stålhand J - - 2005
It was shown in a previous study by Stålhand et al. (2004) that both material and residual strain parameters for an artery can be identified noninvasively from an in vivo clinical pressure-diameter measurement. The only constraints placed on the model parameters in this previous study was a set of simple ...
Coats Paul - - 2005
Atherosclerosis in a major leg artery leads to impaired blood supply, which normally progresses to critical limb ischemia. Atherosclerosis produces substantial alterations of structure and endothelial function in the large conduit arteries. Pressure unloading and ischemia in the distal vasculature bring about alterations in microvascular function. Resistance arteries undergo significant ...
Pakter Helena M - - 2005
BACKGROUND: The extent of arteriolar narrowing has been recognized as a major sign of end-organ damage in patients with hypertension, but most methods used for its evaluation are highly dependent on the observer. We describe a new semi-automated method to measuring arteriolar-to-venous (A/V) ratio in retinal photography and present its ...
Allahdadi Kyan J - - 2005
We reported previously that simulating sleep apnea in rats by exposing them 7 hours per day to intermittent hypoxia/hypercapnia (IH) elevates plasma endothelin-1 and causes hypertension, which is reversed by an endothelin-1 antagonist. We hypothesized that in this model of sleep apnea-induced hypertension, vascular sensitivity to endothelin-1 is increased in ...
Izzard Ashley S - - 2005
Hypertension is known to be associated with an increase in the wall/lumen ratio (W/L) of the resistance arteries. Growth, eutrophic remodelling and changes in arterial distensibility can all contribute to an increase W/L. Wall stress may stimulate growth, whereas remodelling and/or reduced distensibility may be the result of prolonged contraction. ...
Sun Lei - - 2005
High blood pressure (hypertension) is implicated in the development of atherosclerosis. Blood vessels are constantly subjected to stretch due to blood pressure and changes in stretch usually instigate adaptive vascular remodeling, including abnormal growth and proliferation of vascular smooth muscle cells (VSMCs) as well as extracellular matrix (ECM). In this ...
Mulvany Michael J - - 2005
The structure of the resistance vessels in patients with essential hypertension is altered, with reduction of the lumen diameter and increase in wall-to-lumen ratio without change in wall mass, known as eutrophic remodelling. The alteration appears to cause a reduction in the vascular reserve, in particular the coronary reserve (the ...
Kurbel Sven - - 2005
It is generally assumed that almost no pressure gradient exists in the aorta and large arteries. This holds truth in rest, but during heavy exercise, when the resistance of arterioles in active skeletal muscles is diminished, the remaining resistance of large and small arteries might become significant and limit the ...
Abe Kaoru - - 2005
To evaluate the ability of ultrasonically activated shears (USAS) to occlude lymphatic vessels, we investigated the bursting pressure of lymphatic vessels occluded with USAS and compared with pressures in an artery and a vein. The inguinal lymphatic vessels, testicular arteries, and testicular veins were removed from male pigs. The vessels ...
Morris Cassandra - - 2005
This study was designed to directly quantify the effect of localized static magnetic field (SMF) exposure on the diameter of microvessels in adult rat skeletal muscle in vivo. Microvascular networks in the exteriorized rat spinotrapezius microvasculature were exposed to a localized, uniform 70 mT SMF for 15 min. Arteriolar vessel ...
Ple┼čea I E - - 2005
AIMS: The study was performed in order to assess the alterations of extra-parenchymal and intraparenchymal vascular structures in 82 hypertensive patients suspected of primary intraparenchymal hematoma, which died and were autopsied in order to confirm the diagnosis. MATERIAL AND METHODS: The studied material consisted of nervous tissue situated near and ...
Pietrow Paul K - - 2005
BACKGROUND AND PURPOSE: Laparoscopic bipolar instruments are commonly employed to cauterize and divide tissue. A next-generation bipolar device has been developed that employs vapor pulse coagulation energy. We assessed the vessel-sealing capability of this device and quantified thermal spread during application. MATERIALS AND METHODS: Bilateral laparoscopic nephrectomy was performed on ...
Blum M - - 2005
PURPOSE: The effect of elevated blood glucose level on the myogenic response of human retinal arterioles to acute increases in blood pressure is investigated. METHODS: The vascular response to raised blood pressure (Bayliss effect) was measured in 12 healthy volunteers by use of the retinal vessel analyzer (RVA). For a ...
Petersen K A - - 2005
The genuine closed cranial window model, in which the thinned parietal bone constitutes the covering of the preparation, has contributed to a better understanding of the pathophysiological mechanisms in migraine. In its present form, only measurements of the middle meningeal artery (MMA) are performed. The aim of this study was, ...
Gokina Natalia I - - 2005
Several recent studies have implicated the RhoA-Rho kinase pathway in arterial myogenic behavior. The goal of this study was to determine the effects of Rho kinase inhibition (Y-27632) on cerebral artery calcium and diameter responses as a function of transmural pressure. Excised segments of rat posterior cerebral arteries (100-200 microm) ...
Boissonnat J-D - - 2005
Saccular aneurisms illustrate usefulness and possible techniques of image-based modeling of flow in diseased vessels. Aneurism flow is investigated in order to estimate the rupture risk, assuming that the pressure is the major factor and that high-pressure zones are correlated to within-wall strong-stress concentrations. Computational flow is also aimed at ...
Mikhailichenko L A - - 2004
Using implanted camera we studied hamster buccal pouch microvessels under conditions of reduced blood pressure. The correlation (R=0.30-0.85) between the diameter and pressure was observed in 42% vessels. During progressive decrease in blood pressure, R for the majority of left venules was below zero, while left arterioles had equal probability ...
Arts Theo - - 2005
With circulatory pathology, patient-specific simulation of hemodynamics is required to minimize invasiveness for diagnosis, treatment planning, and followup. We investigated the advantages of a smart combination of often already known hemodynamic principles. The CircAdapt model was designed to simulate beat-to-beat dynamics of the four-chamber heart with systemic and pulmonary circulation ...
Lee Kristine E - - 2004
PURPOSE: To describe familial correlations of retinal vessel measurements. METHODS: A standardized examination and interview was administered to a population-based cohort of adults aged 43-86 years. Blood pressure was measured, and family relationships, current smoking status, and photographs of the retina were obtained. Computer-assisted grading was done to determine central ...
Fahner P J - - 2004
Glycerol preservation is an effective method for long-term preservation of skin allografts and has a potential use in preserving arterial allografts. We evaluated the effect of glycerol concentration and incubation period on vessel-wall integrity of rat aortic allografts. No significant differences were measured in breaking strength (2.3 +/- 0.3 N) ...
Phillips Shane A - - 2005
This study tested the hypothesis that evolution of the metabolic syndrome in obese Zucker rats (OZR) leads to impaired dilator reactivity of cerebral resistance arteries vs. responses determined in lean Zucker rats (LZR). Middle cerebral arteries (MCA) from 17-wk-old male LZR and OZR were isolated and cannulated with glass micropipettes. ...
Kurjiaka David T - - 2004
Arteriolar vasomotor responses can include a component that conducts along the vessel through gap junction channels. This study examined conducted vasomotor responses in arterioles of the hypertensive hamster. The cremaster muscle of normotensive (CHF-148) and spontaneously hypertensive (CHF-H4) hamsters was exteriorized. Micropipettes containing phenylephrine (0.1 M) or acetylcholine (ACh; 1.0 ...
Scotland Ramona S - - 2004
Myogenic constriction describes the innate ability of resistance arteries to constrict in response to elevations in intraluminal pressure and is a fundamental determinant of peripheral resistance and, hence, organ perfusion and systemic blood pressure. However, the receptor/cell-type that senses changes in pressure on the blood vessel wall and the pathway ...
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 - - 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, ...
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