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cerebral vascular autoregulation

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https://www.readbyqxmd.com/read/27927653/knockdown-of-add3-impairs-the-myogenic-response-of-renal-afferent-arterioles-and-middle-cerebral-arteries
#1
Fan Fan, Mallikarjuna R Pabbidi, Ying Ge, Longyang Li, Shaoxun Wang, Paige N Mims, Richard J Roman
We have reported that the myogenic response of the renal afferent arteriole (Af-art) and middle cerebral artery (MCA), and autoregulation of renal and cerebral blood flow are impaired in Fawn Hood Hypertensive (FHH) rats. Transfer of a region of chromosome 1 containing gamma-adducin (Add3) from Brown Norway rats rescues the vascular dysfunction and the development of renal disease. To examine whether Add3 is a viable candidate gene altering renal and cerebral hemodynamics in FHH rats, we knocked down the expression of Add3 in rat Af-art and MCA cultured for 36-hours using a 27-mer Dicer-substrate short interfering RNA (DsiRNA)...
December 7, 2016: American Journal of Physiology. Renal Physiology
https://www.readbyqxmd.com/read/27891584/an-observational-study-of-the-macro-and-micro-haemodynamic-implications-of-epidural-anaesthesia-in-children
#2
L Triffterer, P Marhofer, G Lechner, T C Marksz, O Kimberger, W Schmid, D Marhofer
The haemodynamic implications of epidural anaesthesia in children are poorly documented. We report macro- and micro-haemodynamic data from an observational study of 25 children ranging from neonates to six-years old, who underwent surgery conducted with a specific combination of monitoring systems. We analysed 90 min of study-related monitoring after epidural catheterisation, with skin incision taking place after around 30 min. We recorded macrohaemodynamic parameters (monitored using LiDCOrapid) including heart rate, mean arterial pressure, cardiac output, stroke volume, systemic vascular resistance and stroke volume variation...
November 28, 2016: Anaesthesia
https://www.readbyqxmd.com/read/27862767/dynamics-of-cerebral-blood-flow-in-patients-with-mild-non-ischaemic-heart-failure
#3
Christian D Erkelens, Haye H van der Wal, Bauke M de Jong, Jan-Willem Elting, Remco Renken, Marleen Gerritsen, Peter Jan van Laar, Vincent M van Deursen, Peter van der Meer, Dirk J van Veldhuisen, Adriaan A Voors, Gert-Jan Luijckx
AIMS: Heart failure (HF) is associated with tissue hypoperfusion and congestion leading to organ dysfunction. Although cerebral blood flow (CBF) is preserved over a wide range of perfusion pressures in healthy subjects, it is impaired in end-stage HF. We aimed to compare CBF, autoregulation, and cognitive function in patients with mild non-ischaemic HF with healthy controls. METHODS AND RESULTS: Fifteen patients with mild idiopathic dilated cardiomyopathy and 15 matched healthy controls were studied...
November 14, 2016: European Journal of Heart Failure
https://www.readbyqxmd.com/read/27831856/the-dual-role-of-cerebral-autoregulation-and-collateral-flow-in-the-circle-of-willis-after-major-vessel-occlusion
#4
Flora Kennedy McConnell, Stephen Payne
OBJECTIVE: Ischaemic stroke is a leading cause of death and disability. Autoregulation and collateral blood flow through the circle of Willis both play a role in preventing tissue infarction. To investigate the interaction of these mechanisms a one-dimensional steady state model of the cerebral arterial network was created. METHODS: Structural variants of the circle of Willis that present particular risk of stroke were recreated using a network model coupled with: (1) a steady state physiological model of cerebral autoregulation; (2) one wherein the cerebral vascular bed was modelled as a passive resistance...
November 1, 2016: IEEE Transactions on Bio-medical Engineering
https://www.readbyqxmd.com/read/27828873/elevated-markers-of-vascular-remodeling-and-arterial-stiffness-are-associated-with-neurocognitive-function-in-older-hiv-adults-on-suppressive-antiretroviral-therapy
#5
Jessica L Montoya, Jennifer Iudicello, Pariya L Fazeli, Suzi Hong, Michael Potter, Ronald J Ellis, Igor Grant, Scott L Letendre, David J Moore
BACKGROUND: HIV is associated with elevated markers of vascular remodeling that may contribute to arterial fibrosis and stiffening, and changes in pulse pressure (PP). These changes may, in turn, deleteriously affect autoregulation of cerebral blood flow and neurocognitive function. METHODS: To evaluate these mechanisms, we studied markers of vascular remodeling, PP, and neurocognitive function among older (≥50 years of age) HIV-infected (HIV+; n = 72) and HIV-seronegative (HIV-; n = 36) adults...
November 4, 2016: Journal of Acquired Immune Deficiency Syndromes: JAIDS
https://www.readbyqxmd.com/read/27793855/functional-vascular-contributions-to-cognitive-impairment-and-dementia-vcid-mechanisms-and-consequences-of-cerebral-microvascular-dysfunction-in-aging
#6
Peter Toth, Stefano Tarantini, Anna Csiszar, Zoltan I Ungvari
Increasing evidence from epidemiological, clinical and experimental studies indicate that age-related cerebromicrovascular dysfunction and microcirculatory damage play critical roles in the pathogenesis of many types of dementia in the elderly, including Alzheimer's disease. Understanding and targeting the age-related pathophysiological mechanisms that underlie vascular contributions to cognitive impairment and dementia (VCID) is expected to have a major role in preserving brain health in older individuals...
October 28, 2016: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/27662354/lipid-subhyaloid-maculopathy-and-exposure-to-high-altitude
#7
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
https://www.readbyqxmd.com/read/27596833/contributions-of-structural-connectivity-and-cerebrovascular-parameters-to-functional-magnetic-resonance-imaging-signals-in-mice-at-rest-and-during-sensory-paw-stimulation
#8
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
https://www.readbyqxmd.com/read/27526170/comparison-of-two-algorithms-for-analysis-of-perfusion-computed-tomography-data-for-evaluation-of-cerebral-microcirculation-in-chronic-subdural-hematoma
#9
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
https://www.readbyqxmd.com/read/27484894/cerebral-circulation-in-aging
#10
REVIEW
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
https://www.readbyqxmd.com/read/27435029/effect-of-progressive-normobaric-hypoxia-on-dynamic-cerebral-autoregulation
#11
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
https://www.readbyqxmd.com/read/27358581/cerebral-hemodynamics-and-vascular-reactivity-in-mild-and-severe-ischemic-rodent-middle-cerebral-artery-occlusion-stroke-models
#12
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
https://www.readbyqxmd.com/read/27357378/neuropsychological-effects-of-cerebral-amyloid-angiopathy
#13
REVIEW
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
https://www.readbyqxmd.com/read/27272329/-posterior-reversible-encephalopathy-syndrome
#14
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
https://www.readbyqxmd.com/read/27241246/myogenic-and-metabolic-feedback-in-cerebral-autoregulation-putative-involvement-of-arachidonic-acid-dependent-pathways
#15
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
https://www.readbyqxmd.com/read/27235126/optical-measures-of-changes-in-cerebral-vascular-tone-during-voluntary-breath-holding-and-a-sternberg-memory-task
#16
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
https://www.readbyqxmd.com/read/27228963/dynamic-cerebral-autoregulation-is-unrelated-to-decrease-in-external-carotid-artery-blood-flow-during-acute-hypotension-in-healthy-young-men
#17
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
https://www.readbyqxmd.com/read/27211559/h2s-regulates-hypobaric-hypoxia-induced-early-glio-vascular-dysfunction-and-neuro-pathophysiological-effects
#18
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
https://www.readbyqxmd.com/read/27117494/chronic-cerebrovascular-dysfunction-after-traumatic-brain-injury
#19
REVIEW
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
https://www.readbyqxmd.com/read/27100515/molecular-mechanisms-and-cell-signaling-of-20-hydroxyeicosatetraenoic-acid-in-vascular-pathophysiology
#20
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...
June 1, 2016: Frontiers in Bioscience (Landmark Edition)
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