Search results for " blood flow"
showing 10 items of 305 documents
Nitrergic modulation of gastrointestinal function during early endotoxemia.
2006
After bacterial infection, the host reacts by signalling to the central nervous system where a cascade of physiologic, neuroendocrine and behavioural processes is orchestrated, collectively termed the acute phase response. Endotoxemia following Gram-negative bacterial infection induces a wide array of effects, including fever, loss of appetite and changes in gastrointestinal function that attempt to eliminate the challenge and restore homeostasis. Systemic administration of low doses of endotoxin (5-40 microg/kg) to rats is associated with changes in gastrointestinal motor function, inhibition of gastric acid secretion and increase in the gastric mucosal resistance to damage. These changes …
Description of the response of a new multi-parametric brain sensor to physiological and pathophysiological challenges in the cortex of juvenile pigs
2014
AIM Monitoring of intracranial pressure (ICP), local cerebral blood flow (CBF) and oxygen is part of modern intensive critical care medicine. Preclinical evaluation of newly developed catheters that should monitor several parameters simultaneously is reported poorly in the literature. The goal of our study was (1) to evaluate a new multi-parametric sensor in brain tissue and (2) to establish a testing protocol using pathophysiological challenges that target measured parameters of the sensor and autoregulatory boundaries and could be used as preclinical standard protocol in future studies. MATERIAL AND METHODS We describe data from 12 new multi-parametric brain sensors (MPBS) that were impla…
Effect of Hyper- and Hypoventilation on CBF during Anesthesia
1969
Alexander and Wollman [1, 2, 4, 8], Harper [5] and McDowall and other investigators have published observations on CBF during anaesthesia in man and dog, when arterial pCO2 was altered by hyper- or hypoventilation.
Microcirculation after cerebral venous occlusions as assessed by laser Doppler scanning.
1997
✓ Research on cerebral venous circulation disturbances (CVCDs) has been limited partly by the paucity of animal models that produce consistent venous infarction. Occlusion of two adjacent cortical veins in rats by means of a photochemical thrombotic technique provides a minimally invasive, clinically relevant, and reproducible model suited to study the pathophysiology of CVCDs. In this study, the effects of venous occlusion on regional cortical blood flow and the brain damage that ensues were evaluated. Cortical vein occlusion was induced by photoactivation of rose bengal via 100-µm fiberoptic illumination. The cerebral venous flow pattern was examined using fluorescence angiography until 9…
Alterations of regional cerebral blood flow and oxygen saturation in a rat sinus-vein thrombosis model.
1996
Background and Purpose The pathophysiology of sinus-vein thrombosis (SVT) in patients and experimental animals is still poorly understood. This study was designed to examine and further elucidate the pathophysiological sequence of events, especially the relationship between local and regional blood flow and hemoglobin oxygen saturation (HbSO 2 ) detected at identical locations. The use of both parameters as outcome indicators should be compared. Methods SVT was induced by ligation of the superior sagittal sinus (SSS) and slow injection of kaolin-cephalin suspension into the SSS in rats. Regional cerebral blood flow (rCBF) was assessed by laser-Doppler flowmetry together with regional HbSO …
Reinterpreting the Magnetic Resonance Signs of Hemodynamic Impairment in the Brains of Multiple Sclerosis Patients From the Perspective of a Recent D…
2010
Multiple sclerosis patients examined with perfusion magnetic resonance (MR) imaging techniques have been found to have patterns of abnormal blood flow. These include prolonged mean transit time, a trend toward decreased cerebral blood flow in the area of plaques, and decreased cerebral blood flow and prolonged mean transit time within normal-appearing white matter. In-creased cerebral blood flow and volume and decreased mean transit time (compared with the baseline values before the relapse) were found to precede the development of plaques. In addition, susceptibility-weighted imaging utilizing deoxyhemoglobin as the contrast has revealed that venous blood in cerebral veins of multiple scle…
Vascular Microarchitecture of Murine Colitis-Associated Lymphoid Angiogenesis
2009
In permissive tissues, such as the gut and synovium, chronic inflammation can result in the ectopic development of anatomic structures that resemble lymph nodes. These inflammation-induced structures, termed lymphoid neogenesis or tertiary lymphoid organs, may reflect differential stromal responsiveness to the process of lymphoid neogenesis. To investigate the structural reorganization of the microcirculation involved in colonic lymphoid neogenesis, we studied a murine model of dextran sodium sulfate (DSS)-induced colitis. Standard 2-dimensional histology demonstrated both submucosal and intramucosal lymphoid structures in DSS-induced colitis. A spatial frequency analysis of serial histolog…
Cerebral blood flow and cerebral death
1969
At present the diagnosis of cerebral death is based on the absence of manifestations of cerebral function (deep coma, wide pupils, absence of reflexes and spontaneous respiration, isoelectric EEG, etc.) during a variable period of time. However, the absence of vital signs of an organ, even for prolonged periods, is no proof of its death. The death of an organ can only be considered as proved by the demonstration that this organ has remained completely deprived of its blood flow during a period of time that surpasses its ability to survive circulatory arrest. In the case of the brain, the permanent absence of clearance of a radioactive tracer deposed within the brain is considered to demonst…
A versatile model of steady state O2 supply to tissue. Application to skeletal muscle
1990
A model of combined convective and diffusive O2 transport to tissue is suggested which allows for the calculation of PO2 distributions in a cuboid tissue region with arbitrary microvascular geometries and blood flows. Carrier-facilitated O2 diffusion in the erythrocytes and in the tissue and red blood cell reaction kinetics are considered. The model is based on analytical descriptions of the PO2 fields of single erythrocytes surrounded by carrier-free layers in an infinite three-dimensional space containing an O2 carrier such as myoglobin. These PO2 fields are overlaid to obtain a solution of the differential equation of diffusion in respiring tissue. The model has been applied to a situati…