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hydrostatic pressure in blood vessels

James Noraky, George C Verghese, David E Searls, Vasileios A Lioutas, Shruti Sonni, Ajith Thomas, Thomas Heldt
Intracranial pressure (ICP) should ideally be measured in many conditions affecting the brain. The invasiveness and associated risks of the measurement modalities in current clinical practice restrict ICP monitoring to a small subset of patients whose diagnosis and treatment could benefit from ICP measurement. To expand validation of a previously proposed model-based approach to continuous, noninvasive, calibration-free, and patient-specific estimation of ICP to patients with subarachnoid hemorrhage (SAH), we made waveform recordings of cerebral blood flow velocity in several major cerebral arteries during routine, clinically indicated transcranial Doppler examinations for vasospasm, along with time-locked waveform recordings of radial artery blood pressure (APB), and ICP was measured via an intraventricular drain catheter...
2016: Acta Neurochirurgica. Supplement
Mark Butlin, Peta J Hathway, Zahra Kouchaki, Karen Peebles, Alberto P Avolio
Devices that estimate blood pressure from arterial pulse wave velocity (PWV) potentially provide continuous, ambulatory blood pressure monitoring. Accurate blood pressure estimation requires reliable quantification of the relationship between blood pressure and PWV. Regression to population normal values or, when using limb artery PWV, changing hydrostatic blood pressure within the limb provides a calibration index. Population lookup tables require accurate anthropometric correlates, assuming no individual variation...
August 2015: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
Shinsaku Tokuda, Young Hak Kim, Hisako Matsumoto, Shigeo Muro, Toyohiro Hirai, Michiaki Mishima, Mikio Furuse
The relationship between chronic inflammation and cancer is well known. The inflammation increases the permeability of blood vessels and consequently elevates pressure in the interstitial tissues. However, there have been only a few reports on the effects of hydrostatic pressure on cultured cells, and the relationship between elevated hydrostatic pressure and cell properties related to malignant tumors is less well understood. Therefore, we investigated the effects of hydrostatic pressure on the cultured epithelial cells seeded on permeable filters...
2015: PloS One
Mitchell P Wilson, Edward S Johnson, Cynthia Hawkins, Kerry Atkins, Wael Alshaya, Jeffrey A Pugh
Acute hemorrhagic presentation in pilocytic astrocytomas (PAs) has become increasingly recognized. This type of presentation poses a clinically emergent situation in those hemorrhages arising in PAs of the cerebellum, the most frequent site, because of the limited capacity of the posterior fossa to compensate for mass effect, predisposing to rapid neurological deterioration. As examples, we describe two cases of fatal hemorrhagic cerebellar PAs: one of a child with a slowly growing stereotypical WHO Grade I PA with a 1-year period of symptomatology that preceded a rapid clinical deterioration, and another of an asymptomatic child having a PA variant, presenting with progressive obtundation following a presumed Valsalva event...
April 2016: Journal of Neurosurgery. Pediatrics
Mårten Jungner, Roger Siemund, Daniele Venturoli, Peter Reinstrup, Wilhelm SCHALéN, Peter Bentzer
BACKGROUND: Brain edema and intracranial hypertension is deleterious after traumatic brain injury (TBI), but the underlying pathophysiology is complex and poorly understood. One major subject of controversy is the time course and extent of blood-brain barrier (BBB) dysfunction following trauma, and previous studies in humans have only provided semi-quantitative data. The objective of the present study was therefore to quantify changes in BBB-permeability in the early course of TBI, when brain edema is still evolving...
May 2016: Minerva Anestesiologica
Masaaki Suzuki, Ryosuke Kotani
CONCLUSIONS: Hydrostatic positive pressure and vasoconstrictor acidified the cochlear fluids, whereas the vasodilator made the fluids alkaline. CBF might play a role in regulating cochlea fluid pH. OBJECTIVES: Cochlea fluid pH is highly dependent on the HCO3(-)/CO2 buffer system. Cochlear blood flow (CBF) supplies O2 and removes CO2. It is speculated that cochlear blood flow changes might affect the balance of the HCO3(-)/CO2 buffer system in the cochlea. It is known that the elevation of inner ear pressure decreases the CBF, and local application of vasodilating or vasoconstricting agents directly to the cochlea changes the CBF...
2015: Acta Oto-laryngologica
Travis W Hein, Robert H Rosa, Yi Ren, Wenjuan Xu, Lih Kuo
PURPOSE: Vasomotor responses of retinal arterioles to luminal flow/shear stress and VEGF have a critical role in governing retinal blood flow possibly via nitric oxide synthase (NOS) activation. However, the cellular mechanism for flow-sensitive vasomotor activity in relation to VEGF signaling in retinal arterioles has not been characterized. We used an isolated vessel approach to specifically address this issue. METHODS: Porcine retinal arterioles were isolated, cannulated, and pressurized to 55 cm H2O luminal pressure by two independent reservoir systems...
August 2015: Investigative Ophthalmology & Visual Science
Sarah Jones, Helen Bischof, Ingrid Lang, Gernot Desoye, Sue L Greenwood, Edward D Johnstone, Mark Wareing, Colin P Sibley, Paul Brownbill
Increased vascular resistance and reduced fetoplacental blood flow are putative aetiologies in the pathogenesis of fetal growth restriction (FGR); however, the regulating sites and mechanisms remain unclear. We hypothesised that placental vessels dictate fetoplacental resistance and in FGR exhibit endothelial dysfunction and reduced flow-mediated vasodilatation (FMVD). Resistance was measured in normal pregnancies (n = 10) and FGR (n = 10) both in vivo by umbilical artery Doppler velocimetry and ex vivo by dual placental perfusion...
July 15, 2015: Journal of Physiology
V I Sapehin, I D Sapehin
In an acute experiment on the laboratory rabbits there was elaborated and introduced a method of a model simulation for a standard level of intraabdominal pressure (IAP) in values of 50, 100, 150, 200, 250, 300, 350 mm of a water column, using a stand of original construction. Local blood flow (LBF), dilatational (KpCO2) and constrictional (KpO2) reactivity of vessels were determined, using a hydrogen clearance method, as well as the oxygen pressure (pO2) in the intestinal wall tissues, using polarography method, exploiting the electrode blocks of own construction...
March 2014: Klinichna Khirurhiia
Francesco Fambri, Michael Dumbser, Vincenzo Casulli
Blood flow in arterial systems can be described by the three-dimensional Navier-Stokes equations within a time-dependent spatial domain that accounts for the elasticity of the arterial walls. In this article, blood is treated as an incompressible Newtonian fluid that flows through compliant vessels of general cross section. A three-dimensional semi-implicit finite difference and finite volume model is derived so that numerical stability is obtained at a low computational cost on a staggered grid. The key idea of the method consists in a splitting of the pressure into a hydrostatic and a non-hydrostatic part, where first a small quasi-one-dimensional nonlinear system is solved for the hydrostatic pressure and only in a second step the fully three-dimensional non-hydrostatic pressure is computed from a three-dimensional nonlinear system as a correction to the hydrostatic one...
November 2014: International Journal for Numerical Methods in Biomedical Engineering
J Marc Simard, Adam Pampori, Kaspar Keledjian, Cigdem Tosun, Gary Schwartzbauer, Svetlana Ivanova, Volodymyr Gerzanich
Traumatic brain injury (TBI) caused by an explosive blast (blast-TBI) is postulated to result, in part, from transvascular transmission to the brain of a hydrodynamic pulse (a.k.a., volumetric blood surge, ballistic pressure wave, hydrostatic shock, or hydraulic shock) induced in major intrathoracic blood vessels. This mechanism of blast-TBI has not been demonstrated directly. We tested the hypothesis that a blast wave impacting the thorax would induce a hydrodynamic pulse that would cause pathological changes in the brain...
July 15, 2014: Journal of Neurotrauma
Helmut Barz, Ulrich Barz
The paper based on the hypothesis that mechanical impulses cause the transmission of excitement in the peripheral and central nervous system. Possible connections between changes in the tubular neuronal network and the morphological findings of Alzheimer's disease are presented. Additionally, changes in the viscosity of the neuronal cytoplasm and changes in the walls of the neuronal fibers due to the intracellular hydrostatic pressure and pressure waves are considered possible causes of plaques, threads and tangles...
May 2014: Medical Hypotheses
Jessie L-S Au, Peng Guo, Yue Gao, Ze Lu, Michael G Wientjes, Max Tsai, M Guillaume Wientjes
This study established a multiscale computational model for intraperitoneal (IP) chemotherapy, to depict the time-dependent and spatial-dependent drug concentrations in peritoneal tumors as functions of drug properties (size, binding, diffusivity, permeability), transport mechanisms (diffusion, convection), spatial-dependent tumor heterogeneities (vessel density, cell density, pressure gradient), and physiological properties (peritoneal pressure, peritoneal fluid volume). Equations linked drug transport and clearance on three scales (tumor, IP cavity, whole organism)...
May 2014: AAPS Journal
Francesco Ciciarello, Sandro Mandolesi, Aldo Innocente Galeandro, Azzurra Marceca, Michele Rossi, Francesco Fedele, Michele Gesualdo, Francesca Cortese, Annapaola Zito, Francesco Federico, Paolo Livrea, Maria Trojano, Pietro Scicchitano, Marco Matteo Ciccone
The aim of our study was to analyze morphological and functional aspects of cerebral veins by means of ecocolor-Doppler in young (i.e., ≤ 30 years old) and older (i.e., >30 years old) patients suffering from multiple sclerosis. 552 multiple sclerosis patients were evaluated by means of a dedicated Echo-Color-Doppler support (MyLab Vinco echocolor Doppler System, Esaote), in both supine and sitting positions. 458 (83%) showed alterations in their morphological and functional structures of cerebral veins and were divided in two different groups: 1) ≤ 30 (110 patients) and 2) >30 years old (348 patients)...
February 2014: Current Neurovascular Research
Francesco Costanzo, James G Brasseur
There are strong medical motivations to measure changes in material properties of tubular organs, in vivo and in vitro. The current approach estimates hoop stress from intraluminal pressure using the Laplace law and identifies 'elastic modulus' as the slope of a curve fitted hoop stress plotted against strain data. We show that this procedure is fundamentally flawed because muscle and other soft tissue are closely incompressible, so that the total stress includes a volume-preserving material-dependent hydrostatic response that invalidates the method...
March 2015: Mathematical Medicine and Biology: a Journal of the IMA
Einar Stefánsson
A variety of treatment options are available for the treatment of diabetic macular edema. They include laser photocoagulation, anti-VEGF drugs, intravitreal steroids, and vitrectomy with or without release of vitreoretinal traction. A full understanding of the physiological mechanisms of these treatment modalities allows sensible combination of treatment options. Retinal photocoagulation has repeatedly been shown to improve retinal oxygenation, as does vitrectomy. Oxygen naturally reduces VEGF production and thereby decreases leakage of plasma proteins from capillaries into the tissue...
July 2009: Saudi Journal of Ophthalmology: Official Journal of the Saudi Ophthalmological Society
Federico Vozzi, Francesca Bianchi, Arti Ahluwalia, Claudio Domenici
Abundant experimental evidence demonstrates that endothelial cells are sensitive to flow; however, the effect of fluid pressure or pressure gradients that are used to drive viscous flow is not well understood. There are two principal physical forces exerted on the blood vessel wall by the passage of intra-luminal blood: pressure and shear. To analyze the effects of pressure and shear independently, these two stresses were applied to cultured cells in two different types of bioreactors: a pressure-controlled bioreactor and a laminar flow bioreactor, in which controlled levels of pressure or shear stress, respectively, can be generated...
January 2014: Biotechnology Journal
Lara Planas-Paz, Eckhard Lammert
The lymphatic vasculature is essential for fluid homeostasis and transport of immune cells, inflammatory molecules, and dietary lipids. It is composed of a hierarchical network of blind-ended lymphatic capillaries and collecting lymphatic vessels, both lined by lymphatic endothelial cells (LECs). The low hydrostatic pressure in lymphatic capillaries, their loose intercellular junctions, and attachment to the surrounding extracellular matrix (ECM) permit passage of extravasated blood plasma from the interstitium into the lumen of the lymphatic capillaries...
November 2013: Cellular and Molecular Life Sciences: CMLS
Triantafyllos Stylianopoulos, John D Martin, Matija Snuderl, Fotios Mpekris, Saloni R Jain, Rakesh K Jain
The stress harbored by the solid phase of tumors is known as solid stress. Solid stress can be either applied externally by the surrounding normal tissue or induced by the tumor itself due to its growth. Fluid pressure is the isotropic stress exerted by the fluid phase. We recently showed that growth-induced solid stress is on the order of 1.3 to 13.0 kPa (10-100 mmHg)--high enough to cause compression of fragile blood vessels, resulting in poor perfusion and hypoxia. However, the evolution of growth-induced stress with tumor progression and its effect on cancer cell proliferation in vivo is not understood...
July 1, 2013: Cancer Research
Gabriele Multhoff, Peter Vaupel
The immature, chaotic microvasculature of most solid tumors can present a significant impediment to blood-borne delivery, uneven distribution, and compromised penetration of macromolecular anticancer drugs and diagnostic agents from tumor microvessels across the interstitial space to cancer cells. To reach viable tumor cells in relevant concentrations, macromolecular agents are confronted with several barriers to vascular, transvascular, and interstitial transport. Amongst those (1) heterogeneous and poor blood supply, (2) distinctly reduced or even abolished hydrostatic and oncotic pressure gradients across the microvessel wall abrogating the convective transport from the vessel lumen into the interstitial space (impairment of transvascular transport), and (3) impediment of convective transport within the interstitial compartment due to elevated interstitial fluid pressure (IFP) (resulting from hyperpermeable blood vessels coupled with non-functional lymphatics) and a dense structure of the interstitial matrix are the major mechanisms hindering drug delivery...
2012: Frontiers in Oncology
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