Search results for "HEMODYNAMICS"

A Scanning Technique to Measure Regional Cerebral Blood Flow and Oxyhemoglobin Level

2001

OBJECTIVE: The application of a laser scanning technique to measure regional cerebral blood flow (CBF) and tissue hemoglobin oxygenation (HbO 2 ) using the rat closed cranial window preparation is described. METHODS: Twenty-nine male Wistar rats were used to consecutively measure local CBF by laser Doppler flowmetry and tissue HbO 2 by a microspectrophotometric method at multiple corresponding cortical locations. The scanning technique used a computer-controlled micromanipulator. Data from three experimental models are presented: the whisker stimulation model, the ischemia-reperfusion model, and the sinus-vein thrombosis model. Sequential changes in local CBF and HbO 2 data before, during, …

First-degree atrioventricular block and pseudopacemaker syndrome

2013

Immune escape mechanism: defective resting and stimulated leukocyte-endothelium interaction in hepatocellular carcinoma of the rat.

2004

Hepatocellular carcinoma represents an increasing therapeutic challenge due to its high incidence and early metastasis. Numerous studies have demonstrated the influence of the vascular system on tumor growth and development. In addition, the role of leukocyte-endothelium interaction in tumor vessels is of particular significance with regard to immunological tumor therapy. In this study we used an experimental in vivo animal model that allows a quantitative analysis on vessel morphology, microcirculation, and leukocyte-endothelium interaction. The vessel architecture in tumor tissue was found to be extremely heterogeneous, with a consecutively variable blood flow velocity. Following superfus…

Stimulation of regional lymphatic and blood flow by epicutaneous oxazolone.

2002

The application of the epicutaneous antigen oxazolone results in persistent induration and erythema; however, the relative changes in lymph and blood flow in the inflammatory skin are largely unknown. To define the contribution of lymph and blood flow to the clinical appearance of cutaneous inflammation, we studied the sheep ear after the application of oxazolone. As a model for the study of these changes, the sheep ear had several experimental advantages: 1) a simplified superficial vascular network, 2) defined lymphatic drainage, and 3) an avascular and alymphatic cartilaginous barrier. Lymph flow was continuously monitored by cannulation of the prescapular efferent lymph duct. Blood flo…

Cerebral blood flow alterations in a rat model of cerebral sinus thrombosis.

1993

Outcome from sinus vein thrombosis is very variable, with symptoms from headache to coma. Experimental findings suggest that an involvement of cortical veins is necessary to affect the cerebral microcirculation. Laser Doppler flowmetry was used to investigate the regional and temporal changes in local cortical blood flow after experimental occlusion and thrombosis of the superior sagittal sinus and tributary cortical veins in rats. Thrombosis was induced by slow injection of kaolin-cephalin suspension after frontal and caudal ligation of the sagittal sinus in rats. Local cerebral blood flow was measured by laser Doppler flowmetry and correlated with parenchymal damage found 24 hours after i…

Plastic foil technique attenuates inflammation in mesenteric intravital microscopy.

2000

Abstract Background. Interpretation of intravital microscopic observations is complicated by the “inflammatory”-type response to the trauma inflicted on the tissue by the surgical preparation. The present study evaluates different experimental conditions for prolonged observations of the mesenteric microcirculation in the rat. Methods. The mesentery was exteriorized through a median laparotomy and subjected to an organ bath or a modified plastic foil technique. Hemodynamic, metabolic, respiratory, and microcirculatory data were analyzed. Results. In contrast to the plastic foil technique, which yielded stable baseline values over a 5-h observation period, venular velocity and wall shear rat…

Increased Expression of AQP 1 and AQP 5 in Rat Lungs Ventilated with Low Tidal Volume is Time Dependent

2014

BACKGROUND AND GOALS: Mechanical ventilation (MV) can induce or worsen pulmonary oedema. Aquaporins (AQPs) facilitate the selective and rapid bi-directional movement of water. Their role in the development and resolution of pulmonary oedema is controversial. Our objectives are to determine if prolonged MV causes lung oedema and changes in the expression of AQP 1 and AQP 5 in rats. METHODS: 25 male Wistar rats were subjected to MV with a tidal volume of 10 ml/kg, during 2 hours (n = 12) and 4 hours (n = 13). Degree of oedema was compared with a group of non-ventilated rats (n = 5). The expression of AQP 1 and AQP 5 were determined by western immunoblotting, measuring the amount of mRNA (prev…

Color Doppler Hemodynamics of Giant Cell Arteritis

1994

Objectives: To determine quantitative and qualitative hemodynamic alterations within the ophthalmic, central retinal, and short posterior ciliary arteries in patients with giant cell arteritis (GCA) proved by biopsy specimen. Design, Patients, and Setting: A consecutive case series of patients with GCA referred to an urban eye hospital who were evaluated with color Doppler imaging that was used to analyze orbital blood flow velocities and vascular resistance in 22 consecutive patients with GCA compared with age and sex-matched controls. Results: Patients with GCA all demonstrated significantly reduced central retinal and short posterior ciliary arterial mean flow velocities as well as signi…

Three-dimensional parametric modeling of bicuspid aortopathy and comparison with computational flow predictions

2016

Bicuspid aortic valve (BAV)-associated ascending aneurysmal aortopathy (namely “bicuspid aortopathy”) is a heterogeneous disease making surgeon predictions particularly challenging. Computational flow analysis can be used to evaluate the BAV-related hemodynamic disturbances, which likely lead to aneurysm enlargement and progression. However, the anatomic reconstruction process is time consuming so that predicting hemodynamic and structural evolution by computational modeling is unfeasible in routine clinical practice. The aim of the study was to design and develop a parametric program for three-dimensional (3D) representations of aneurysmal aorta and different BAV phenotypes starting fr…

Particle image velocimetry study of the celiac trunk hemodynamic induced by continuous-flow left ventricular assist device

2017

Abstract Whereas left ventricular assist device (LVAD) is the gold-standard therapy for patients with heart failure, gastrointestinal bleeding is one of the most common complications. LVAD implantation may remarkably impact aortic hemodynamics so that experimental and computational flow analyses can be used to study the disease mechanisms. Here we present an experimentally-calibrated computational model of the celiac trunk hemodynamic of a LVAD-supported patient who experienced bleeding after device implantation. Specifically, both particle image velocimetry (PIV) and echocardiography were used to measure and compare flow distributions in each branch of a phantom model of the patient abdomi…