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cerebral vascular autoregulation

Roberta Rosas Petrocinio, Elga Dias Gomes
BACKGROUND: High altitude retinopathy (HAR) includes a number of diseases related to high altitude such as acute mountain sickness (AMS), high altitude pulmonary edema (HAPE) and high altitude cerebral edema (HACE). High altitude retinopathy is mainly characterized by retinal hemorrhages, usually sparing the macular region, a condition specifically known as high altitude retinal hemorrhages (HARH). The pathogenesis of HARH is unclear. Many studies show that lack of oxygen causes an inadequate autoregulation of retinal circulation, causing vascular incompetence...
2016: Aerospace Medicine and Human Performance
Aileen Schroeter, Joanes Grandjean, Felix Schlegel, Bechara J Saab, Markus Rudin
Previously, we reported widespread bilateral increases in stimulus-evoked functional magnetic resonance imaging signals in mouse brain to unilateral sensory paw stimulation. We attributed the pattern to arousal-related cardiovascular changes overruling cerebral autoregulation thereby masking specific signal changes elicited by local neuronal activity. To rule out the possibility that interhemispheric neuronal communication might contribute to bilateral functional magnetic resonance imaging responses, we compared stimulus-evoked functional magnetic resonance imaging responses to unilateral hindpaw stimulation in acallosal I/LnJ, C57BL/6, and BALB/c mice...
September 5, 2016: Journal of Cerebral Blood Flow and Metabolism
Alexey O Trofimov, George Kalentiev, Oleg Voennov, Michail Yuriev, Darya Agarkova, Svetlana Trofimova, Denis E Bragin
The aim of this work was comparison of two algorithms of perfusion computed tomography (PCT) data analysis for evaluation of cerebral microcirculation in the perifocal zone of chronic subdural hematoma (CSDH). Twenty patients with CSDH after polytrauma were included in the study. The same PCT data were assessed quantitatively in cortical brain region beneath the CSDH (zone 1), and in the corresponding contralateral brain hemisphere (zone 2) without and with the use of perfusion calculation mode excluding vascular pixel 'Remote Vessels' (RV); 1st and 2nd analysis method, respectively...
2016: Advances in Experimental Medicine and Biology
Ken Nagata, Takashi Yamazaki, Daiki Takano, Tetsuya Maeda, Yumi Fujimaki, Taizen Nakase, Yuichi Sato
Cerebral circulation is known to be protected by the regulatory function against the hypoperfusion that will affect the cognitive function as a result of brain ischemia and energy failure. The regulatory function includes cerebrovascular autoregulation, chemical control, metabolic control, and neurogenic control, and those compensatory mechanisms can be influenced by hypertension, atherosclerosis, cardiac diseases, cerebrovascular diseases and aging. On the other hand, large and/or small infarction, intracranial hemorrhage, subarachnoid hemorrhage, atherosclerosis, amylod angiopathy are also more directly associated with cognitive decline not only in those with vascular cognitive impairment or vascular dementia but also those with Alzheimer's disease...
September 2016: Ageing Research Reviews
Masahiro Horiuchi, Junko Endo, Shohei Dobashi, Masataka Kiuchi, Katsuhiro Koyama, Andrew W Subudhi
What is the central question of this study? Acute hypoxia reduces dynamic cerebral autoregulation (dCA); however, it is unclear what level of hypoxia is necessary to exert this effect. We sought to investigate whether dCA would be reduced during progressive periods of normobaric hypoxia using a duplex Doppler ultrasound technique to evaluate the volumetric blood flow. What is the main finding and its importance? We showed that dCA decreased linearly as inspired O2 decreased from 21 to 12%. Additionally, symptoms of acute mountain sickness were related to changes in dCA...
October 1, 2016: Experimental Physiology
Jeongeun Sim, Areum Jo, Bok-Man Kang, Sohee Lee, Oh Young Bang, Chaejeong Heo, Gil-Ja Jhon, Youngmi Lee, Minah Suh
Ischemia can cause decreased cerebral neurovascular coupling, leading to a failure in the autoregulation of cerebral blood flow. This study aims to investigate the effect of varying degrees of ischemia on cerebral hemodynamic reactivity using in vivo real-time optical imaging. We utilized direct cortical stimulation to elicit hyper-excitable neuronal activation, which leads to induced hemodynamic changes in both the normal and middle cerebral artery occlusion (MCAO) ischemic stroke groups. Hemodynamic measurements from optical imaging accurately predict the severity of occlusion in mild and severe MCAO animals...
June 2016: Experimental Neurobiology
Matthew Schrag, Howard Kirshner
Cerebral amyloid angiopathy is a condition of the cerebral arterioles and to a lesser extent capillaries and veins, wherein beta-amyloid is deposited. In arterioles, this preferentially targets vascular smooth muscle cells and in the later stages undermines the stability of the vessel. This condition is frequently comorbid with Alzheimer's disease and its role in cognitive impairment and dementia is a topic of considerable recent research. This article reviews recent literature which confirms that CAA independently contributes to cognitive impairment by potentiating the neurodegeneration of Alzheimer's disease, by predisposing to microhemorrhagic and microischemic injury to the brain parenchyma, and by interfering with the autoregulation of CNS blood flow...
August 2016: Current Neurology and Neuroscience Reports
M Fischer, E Schmutzhard
Posterior reversible encephalopathy syndrome refers to a neurological disorder characterized by headache, disorders of consciousness, visual disturbances, epileptic seizures, and subcortical vasogenic edema. About two thirds of patients develop neurological symptoms, which are associated with blood pressure fluctuations. One hypothesis is that hypertensive episodes cause autoregulatory failure, and values above the upper limit of cerebral autoregulation result in a breakthrough followed by hyperperfusion and blood-brain barrier dysfunction...
June 2016: Medizinische Klinik, Intensivmedizin und Notfallmedizin
Ronan M G Berg
The present paper presents a mechanistic model of cerebral autoregulation, in which the dual effects of the arachidonic acid metabolites 20-hydroxyeicosatetraenoic acid (20-HETE) and epoxyeicosatrienoic acids (EETs) on vascular smooth muscle mediate the cerebrovascular adjustments to a change in cerebral perfusion pressure (CPP). 20-HETE signalling in vascular smooth muscle mediates myogenic feedback to changes in vessel wall stretch, which may be modulated by metabolic feedback through EETs released from astrocytes and endothelial cells in response to changes in brain tissue oxygen tension...
July 2016: Medical Hypotheses
Chin Hong Tan, Kathy A Low, Nils Schneider-Garces, Benjamin Zimmerman, Mark A Fletcher, Edward L Maclin, Antonio M Chiarelli, Gabriele Gratton, Monica Fabiani
The human cerebral vasculature responds to changes in blood pressure and demands for oxygenation via cerebral autoregulation. Changes in cerebrovascular tone (vasoconstriction and vasodilation) also mediate the changes in blood flow measured by the BOLD fMRI signal. This cerebrovascular reactivity is known to vary with age. In two experiments, we demonstrate that cerebral pulse parameters measured using optical imaging can quantify changes in cerebral vascular tone, both globally and locally. In experiment 1, 51 older adults (age range=55-87) performed a voluntary breath-holding task while cerebral pulse amplitude measures were taken...
July 2016: Biological Psychology
Shigehiko Ogoh, Henrik Sørensen, Ai Hirasawa, Hiroyuki Sasaki, Takuro Washio, Takeshi Hashimoto, Damian M Bailey, Niels H Secher
What is the central question of this study? Dynamic cerebral autoregulation (CA) is impaired by sympathetic blockade, and the external carotid artery (ECA) vascular bed may prevent adequate internal carotid artery blood flow. We examined whether α1 -receptor blockade-induced attenuation of dynamic CA is related to reduced ECA vasoconstriction. What is the main finding and its importance? α1 -Receptor blockade attenuated dynamic CA, but in contrast to our hypothesis did not affect the ECA blood flow response to acute hypotension...
August 1, 2016: Experimental Physiology
Gaurav Kumar, Aastha Chhabra, Shalini Mishra, Haroon Kalam, Dhiraj Kumar, Ramniwas Meena, Yasmin Ahmad, Kalpana Bhargava, Dipti N Prasad, Manish Sharma
Hypobaric Hypoxia (HH) is an established risk factor for various neuro-physiological perturbations including cognitive impairment. The origin and mechanistic basis of such responses however remain elusive. We here combined systems level analysis with classical neuro-physiological approaches, in a rat model system, to understand pathological responses of brain to HH. Unbiased 'statistical co-expression networks' generated utilizing temporal, differential transcriptome signatures of hippocampus-centrally involved in regulating cognition-implicated perturbation of Glio-Vascular homeostasis during early responses to HH, with concurrent modulation of vasomodulatory, hemostatic and proteolytic processes...
April 2016: EBioMedicine
Amandine Jullienne, Andre Obenaus, Aleksandra Ichkova, Catherine Savona-Baron, William J Pearce, Jerome Badaut
Traumatic brain injuries (TBI) often involve vascular dysfunction that leads to long-term alterations in physiological and cognitive functions of the brain. Indeed, all the cells that form blood vessels and that are involved in maintaining their proper function can be altered by TBI. This Review focuses on the different types of cerebrovascular dysfunction that occur after TBI, including cerebral blood flow alterations, autoregulation impairments, subarachnoid hemorrhage, vasospasms, blood-brain barrier disruption, and edema formation...
July 2016: Journal of Neuroscience Research
Fan Fan, Ying Ge, Wenshan Lv, Matthew R Elliott, Yoshikazu Muroya, Takashi Hirata, George W Booz, Richard J Roman
Cytochrome P450s enzymes catalyze the metabolism of arachidonic acid to epoxyeicosatrienoic acids (EETs), dihydroxyeicosatetraenoic acid and hydroxyeicosatetraeonic acid (HETEs). 20-HETE is a vasoconstrictor that depolarizes vascular smooth muscle cells by blocking K+ channels. EETs serve as endothelial derived hyperpolarizing factors. Inhibition of the formation of 20-HETE impairs the myogenic response and autoregulation of renal and cerebral blood flow. Changes in the formation of EETs and 20-HETE have been reported in hypertension and drugs that target these pathways alter blood pressure in animal models...
2016: Frontiers in Bioscience (Landmark Edition)
N K Sviridova, V V Yavorsky
Intrigue progression of hypertensive encephalopathy (HE) in older patients is that the development of cognitive impairment and high blood pressure underestimated, aslo exist without clinical manifestations. In recent decades convincing proved that the basis for the development of various diseases is cerebral dysfunction systems regulating brain blood flow, including--autoregulation system, which largely affects the blood supply to the brain. This explains the fact that patients with chronic brain ischemia cerebral hemodynamic status largely depends on the condition and stability of the regulatory mechanisms of systemic and cerebral hemodynamics, particularly of systemic blood pressure, regional cerebral blood supply, normalization which, in the early stages of development disorders, prevents of serious complications...
July 2015: Likars'ka Sprava
Hiroyuki Sasaki, Ai Hirasawa, Takuro Washio, Shigehiko Ogoh
PURPOSE: Drinking coffee causes caffeine-induced physiological alterations such as increases in arterial blood pressure, sympathetic nerve activity, cerebral vasoconstriction, etc., and these physiological alterations may be associated with a reduced risk of cerebral vascular disease. However, the effect of coffee drinking on dynamic cerebral blood flow (CBF) regulation remains unclear. The aim of this study was to test our hypothesis that coffee drinking enhances dynamic cerebral autoregulation...
May 2016: European Journal of Applied Physiology
Anthony Fok, Ronil V Chandra, Matthew Gutman, Matthew Ligtermoet, Udaya Seneviratne, Peter Kempster
A 33-year-old woman presented with severe visual loss from fulminant idiopathic intracranial hypertension. Her lumbar puncture opening pressure was 97 cm H2O. Soon after lumboperitoneal shunt surgery, she had a generalized tonic-clonic seizure. Magnetic resonance imaging demonstrated frontal subarachnoid hemorrhage (SAH) and neuroimaging findings consistent with posterior reversible encephalopathy syndrome (PRES). We hypothesize that an abrupt drop in intracranial pressure after lumboperitoneal shunting led to maladjustment of cerebral vascular autoregulation, which caused SAH and PRES...
June 2016: Journal of Neuro-ophthalmology: the Official Journal of the North American Neuro-Ophthalmology Society
Md Zahorul Islam, Cuong Van Dao, Mitsuya Shiraishi, Atsushi Miyamoto
AIMS: Methylmercury (MeHg) exposure results in increased risk of hypertension and cardiovascular diseases. In this study, we aimed to investigate whether the in vivo exposure of MeHg in mice affects blood pressure and basilar arterial responses to angiotensin II (Ang II) and acetylcholine (ACh), which are important modulators of cerebrovascular autoregulation. MAIN METHODS: Mice were exposed to MeHg (40ppm) in drinking water for 21days. Blood pressure was measured in conscious mice by an indirect tail-cuff method...
February 15, 2016: Life Sciences
Hui Huang, Mohamed Al-Shabrawey, Mong-Heng Wang
Arachidonic acid (AA) is metabolized by cyclooxygenase (COX) and cytochrome P450 (CYP) enzymes into eicosanoids, which are involved in cardiovascular diseases and stroke. Evidence has demonstrated the important functions of these eicosanoids in regulating cerebral vascular tone, cerebral blood flow, and autoregulation of cerebral circulation. Although COX-2 inhibitors have been suggested as potential treatments for stroke, adverse events, including an increased risk of stroke, occur following long-term use of coxibs...
January 2016: Prostaglandins & Other Lipid Mediators
Jin Yang, John W Clark
We here review existing models of vascular smooth muscle cell, endothelial cell and cell-cell communication, which have been developed to better understand vascular tone and blood flow autoregulation. In particular, we discuss models that intended to explain modulation of myogenic tone by intraluminal pressure in resistance arterioles. Modeling efforts in the recent past have witnessed a shift from empirical models to models with mechanistic details that underscore different physical aspects of vascular regulation...
2015: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
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