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https://www.readbyqxmd.com/read/28719038/static-cerebrovascular-pressure-autoregulation-remains-intact-during-deep-hypothermia
#1
Dheeraj Goswami, Katherine McLeod, Samantha Leonard, Kathleen Kibler, Ronald Blaine Easley, Charles D Fraser, Dean Andropoulos, Ken Brady
BACKGROUND: Clinical studies measuring cerebral blood flow in infants during deep hypothermia have demonstrated diminished cerebrovascular pressure autoregulation. The coexistence of hypotension in these cohorts confounds the conclusion that deep hypothermia impairs cerebrovascular pressure autoregulation. AIM: We sought to compare the lower limit of autoregulation and the static rate of autoregulation between normothermic and hypothermic piglets. METHODS: Twenty anesthetized neonatal piglets (5-7 days old; 10 normothermic and 10 hypothermic to 20°C) had continuous measurements of cortical red cell flux using laser Doppler flowmetry, while hemorrhagic hypotension was induced without cardiopulmonary bypass...
July 18, 2017: Paediatric Anaesthesia
https://www.readbyqxmd.com/read/28717354/blood-pressure-and-penumbral-sustenance-in-stroke-from-large-vessel-occlusion
#2
REVIEW
Robert W Regenhardt, Alvin S Das, Christopher J Stapleton, Ronil V Chandra, James D Rabinov, Aman B Patel, Joshua A Hirsch, Thabele M Leslie-Mazwi
The global burden of stroke remains high, and of the various subtypes of stroke, large vessel occlusions (LVOs) account for the largest proportion of stroke-related death and disability. Several randomized controlled trials in 2015 changed the landscape of stroke care worldwide, with endovascular thrombectomy (ET) now the standard of care for all eligible patients. With the proven success of this therapy, there is a renewed focus on penumbral sustenance. In this review, we describe the ischemic penumbra, collateral circulation, autoregulation, and imaging assessment of the penumbra...
2017: Frontiers in Neurology
https://www.readbyqxmd.com/read/28710541/injury-induced-purinergic-signalling-molecules-upregulate-pluripotency-gene-expression-and-mitotic-activity-of-progenitor-cells-in-the-zebrafish-retina
#3
Matías P Medrano, Claudio A Bejarano, Ariadna G Battista, Graciela D Venera, Ramón O Bernabeu, Maria Paula Faillace
Damage in fish activates retina repair that restores sight. The purinergic signalling system serves multiple homeostatic functions and has been implicated in cell cycle control of progenitor cells in the developing retina. We examined whether changes in the expression of purinergic molecules were instrumental in the proliferative phase after injury of adult zebrafish retinas with ouabain. P2RY1 messenger RNA (mRNA) increased early after injury and showed maximal levels at the time of peak progenitor cell proliferation...
July 14, 2017: Purinergic Signalling
https://www.readbyqxmd.com/read/28699412/pressure-autoregulation-measurement-techniques-in-adult-tbi-part-ii-a-scoping-review-of-continuous-methods
#4
Frederick Adam Zeiler, Joseph Donnelly, Leanne Calviello, Peter Smieleweski, David Menon, Marek Czosnyka
To perform systematically a scoping review of the literature on commonly described continuous autoregulation measurement techniques in adult TBI. The goal was to provide an overview of methodology and comprehensive reference library of the available literature for each technique. Five separate small systematic reviews were conducted for each of the continuous techniques: pressure reactivity index (PRx), laser Doppler flowmetry (LDF), near infrared spectroscopy (NIRS) techniques, brain tissue oxygen tension (PbtO2), and thermal diffusion (TD) techniques...
July 12, 2017: Journal of Neurotrauma
https://www.readbyqxmd.com/read/28696277/learning-from-adversity
#5
Robert B Bourret
Many two-component regulatory systems, including Escherichia coli PhoRB, are positively autoregulated, so that stimuli result in an increase in the concentration of signaling proteins. When the quantity of signaling proteins depends on exposure history, how do past conditions affect future responses to stimuli? Hoffer et al. previously reported (J Bacteriol 183:4914-4917, 2001, https://doi.org/10.1128/JB.183.16.4914-4917.2001) that E. coli "learn" from phosphate starvation and respond more rapidly to subsequent episodes of starvation...
July 10, 2017: Journal of Bacteriology
https://www.readbyqxmd.com/read/28694108/increased-blood-pressure-variability-upon-standing-up-improves-reproducibility-of-cerebral-autoregulation-indices
#6
Adam Mahdi, Dragana Nikolic, Anthony A Birch, Mette S Olufsen, Ronney B Panerai, David M Simpson, Stephen J Payne
Dynamic cerebral autoregulation, that is the transient response of cerebral blood flow to changes in arterial blood pressure, is currently assessed using a variety of different time series methods and data collection protocols. In the continuing absence of a gold standard for the study of cerebral autoregulation it is unclear to what extent does the assessment depend on the choice of a computational method and protocol. We use continuous measurements of blood pressure and cerebral blood flow velocity in the middle cerebral artery from the cohorts of 18 normotensive subjects performing sit-to-stand manoeuvre...
July 7, 2017: Medical Engineering & Physics
https://www.readbyqxmd.com/read/28694107/effects-of-non-physiological-blood-pressure-artefacts-on-cerebral-autoregulation
#7
Adam Mahdi, Erica M Rutter, Stephen J Payne
Cerebral autoregulation refers to the brain's regulation mechanisms that aim to maintain the cerebral blood flow approximately constant. It is often assessed by the autoregulation index (ARI). ARI uses arterial blood pressure and cerebral blood flow velocity time series to produce a ten-scale index of autoregulation performance (0 denoting the absence of and 9 the strongest autoregulation). Unfortunately, data are rarely free from various artefacts. Here, we consider four of the most common non-physiological blood pressure artefacts (saturation, square wave, reduced pulse pressure and impulse) and study their effects on ARI for a range of different artefact sizes...
July 7, 2017: Medical Engineering & Physics
https://www.readbyqxmd.com/read/28681121/indexes-of-cerebral-autoregulation-do-not-reflect-impairment-in-syncope-insights-from-head-up-tilt-test-of-vasovagal-and-autonomic-failure-subjects
#8
Pedro Castro, João Freitas, Rosa Santos, Ronney Panerai, Elsa Azevedo
PURPOSE: The study of dynamic cerebral autoregulation (CA), which adapts cerebral blood flow to arterial blood pressure (ABP) fluctuations, has been limited in orthostatic intolerance syndromes, mainly due to its stationary prerequisites hardly to meet during maneuvers to provoke syncope itself. New techniques of continuous estimates of CA could overcome this pitfall. We aimed to evaluate CA during head-up tilt test in common conditions causing syncope. METHODS: We compared three groups: eight controls; eight patients with autonomic failure due to familial amyloidotic polyneuropathy; eight patients with vasovagal syncope (VVS)...
July 5, 2017: European Journal of Applied Physiology
https://www.readbyqxmd.com/read/28674514/aspects-on-the-physiological-and-biochemical-foundations-of-neurocritical-care
#9
REVIEW
Carl-Henrik Nordström, Lars-Owe Koskinen, Magnus Olivecrona
Neurocritical care (NCC) is a branch of intensive care medicine characterized by specific physiological and biochemical monitoring techniques necessary for identifying cerebral adverse events and for evaluating specific therapies. Information is primarily obtained from physiological variables related to intracranial pressure (ICP) and cerebral blood flow (CBF) and from physiological and biochemical variables related to cerebral energy metabolism. Non-surgical therapies developed for treating increased ICP are based on knowledge regarding transport of water across the intact and injured blood-brain barrier (BBB) and the regulation of CBF...
2017: Frontiers in Neurology
https://www.readbyqxmd.com/read/28674072/counterbalancing-regulation-in-response-memory-of-a-positively-autoregulated-two-component-system
#10
Rong Gao, Katherine A Godfrey, Mahir A Sufian, Ann M Stock
Fluctuations in nutrient availability often result in recurrent exposures to the same stimulus condition. The ability to memorize the past event and use the "memory" to make adjustments to current behaviors can lead to more efficient adaptation to the recurring stimulus. A short-term phenotypic memory can be conferred via carry-over of the response proteins to facilitate the recurrent response but the additional accumulation of response proteins can lead to deviation from response homeostasis. We used the Escherichia coli PhoB/PhoR two-component system (TCS) as a model system to study how cells cope with the recurrence of Pi starvation conditions...
July 3, 2017: Journal of Bacteriology
https://www.readbyqxmd.com/read/28673811/fluid-attenuated-inversion-recovery-vascular-hyperintensities-in-patients-with-transient-ischemic-attack
#11
Marcelo Marinho de Figueiredo, Edson Amaro Júnior, Maramélia Araújo de Miranda Alves, Marcela Vazzoler, Renata Carolina Acre Nunes Miranda, Gisele Sampaio Silva
BACKGROUND: Fluid-attenuated inversion recovery (FLAIR) vascular hyperintensities (FVHs) are common in patients with acute ischemic stroke, possibly representing impaired hemodynamics in the ischemic territory due to intracranial steno-occlusive disease. There are few reports on FVHs in patients with transient ischemic attack (TIA). AIMS: We investigated the prevalence of FVHs and its clinical correlations in patients with TIA. METHODS: We evaluated consecutive patients admitted with TIA from February 2009 to June 2012 who had undergone magnetic resonance imaging within 30 hours of symptoms onset and intracranial and extracranial vascular imaging...
June 30, 2017: Journal of Stroke and Cerebrovascular Diseases: the Official Journal of National Stroke Association
https://www.readbyqxmd.com/read/28673505/the-first-sign-of-loss-of-consciousness
#12
B S Typ Whinnery, Estrella M Forster
The first clinically observable sign of an unconsciousness episode (UNCE) serves as the temporal sequence (kinetics) onset point for neurological events occurring during the loss of consciousness, unconsciousness and recovery of consciousness phases of the UNCE. The initial neurologic signs of 212 individuals exposed to gradual (N=114) and rapid (N=98) onset +Gz acceleration stress, inducing the ischemic LOC phase in 83.3±18.6s and 8.89±1.52s; p<0.001respectively, were determined. The duration of the unconscious phase (considered absolute incapacitation) was 10...
June 30, 2017: Physiology & Behavior
https://www.readbyqxmd.com/read/28673382/rational-use-of-dopamine-in-hypotensive-newborns-improving-our-understanding-of-the-effect-on-cerebral-autoregulation
#13
Vibeke Ramsgaard Eriksen
Hypotension in critically ill newborn infants is associated with higher mortality and higher risk of cerebral injuries. Yet treating hypotension has never been shown to improve outcomes. In fact, some studies have found that hypotensive newborn infants who were treated with dopamine fared worse than a comparable group of newborn infants who were not. Therefore, a concern has been raised that dopamine might cause the observed adverse outcomes. Cerebral autoregulation is a protective mechanism that maintains a fairly constant cerebral blood flow despite fluctuations in blood pressure...
July 2017: Danish Medical Journal
https://www.readbyqxmd.com/read/28669777/impaired-autoregulation-of-blood-flow-at-the-optic-nerve-head-during-vitrectomy-in-patients-with-type-2-diabetes
#14
Ryuya Hashimoto, Tetsuya Sugiyama, Hidetaka Masahara, Masashi Sakamoto, Makoto Ubuka, Takatoshi Maeno
PURPOSE: To determine whether type 2 diabetes (T2DM) influences autoregulation of optic nerve head (ONH) blood flow during vitrectomy. DESIGN: Cohort study METHODS: Thirteen eyes of 13 subjects with T2DM and 30 eyes of 30 controls without T2DM undergoing vitrectomy for epiretinal membrane or macular hole were included. Following 25-gauge vitrectomy, we measured the mean blur rate (MBR), an index of ONH blood flow, in the vascular area (vascular MBR) and in the tissue area (tissue MBR) using laser speckle flowgraphy...
June 29, 2017: American Journal of Ophthalmology
https://www.readbyqxmd.com/read/28668343/changes-in-arterial-cerebral-blood-volume-during-lower-body-negative-pressure-measured-with-mri
#15
Joseph R Whittaker, Molly G Bright, Ian D Driver, Adele Babic, Sharmila Khot, Kevin Murphy
Cerebral Autoregulation (CA), defined as the ability of the cerebral vasculature to maintain stable levels of blood flow despite changes in systemic blood pressure, is a critical factor in neurophysiological health. Magnetic resonance imaging (MRI) is a powerful technique for investigating cerebrovascular function, offering high spatial resolution and wide fields of view (FOV), yet it is relatively underutilized as a tool for assessment of CA. The aim of this study was to demonstrate the potential of using MRI to measure changes in cerebrovascular resistance in response to lower body negative pressure (LBNP)...
June 28, 2017: NeuroImage
https://www.readbyqxmd.com/read/28667557/atherosclerosis
#16
Mohammed Shamim Rahman, Kevin Woollard
In this chapter, we discuss the manner through which the immune system regulates the cardiovascular system in health and disease. We define the cardiovascular system and elements of atherosclerotic disease, the main focus in this chapter. Herein we elaborate on the disease process that can result in myocardial infarction (heart attack), ischaemic stroke and peripheral arterial disease. We have discussed broadly the homeostatic mechanisms in place that help autoregulate the cardiovascular system including the vital role of cholesterol and lipid clearance as well as the role lipid homeostasis plays in cardiovascular disease in the context of atherosclerosis...
2017: Advances in Experimental Medicine and Biology
https://www.readbyqxmd.com/read/28664392/validation-of-near-infrared-spectroscopy-for-monitoring-cerebral-autoregulation-in-comatose-patients
#17
Lucia Rivera-Lara, Romergryko Geocadin, Andres Zorrilla-Vaca, Ryan Healy, Batya R Radzik, Caitlin Palmisano, Marek Mirski, Wendy C Ziai, Charles Hogue
BACKGROUND: Transcranial Doppler (TCD) noninvasively measures cerebral blood flow (CBF) velocity and is a well-studied method to monitor cerebral autoregulation (CA). Near-infrared spectroscopy (NIRS) has emerged as a promising noninvasive method to determine CA continuously by using regional cerebral oxygen saturation (rSO2) as a surrogate for CBF. Little is known about its accuracy to determine CA in patients with intracranial lesions. The purpose of this study was to assess the accuracy of rSO2-based CA monitoring with TCD methods in comatose patients with acute neurological injury...
June 29, 2017: Neurocritical Care
https://www.readbyqxmd.com/read/28657491/novel-noninvasive-method-of-cerebrovascular-blood-volume-assessment-using-brain-bioimpedance
#18
Mohamad Hakam Tiba, Brendan M McCracken, Sardar Ansari, Ashwin Belle, Brandon C Cummings, Venkatakrishna Rajajee, Parag G Patil, Hasan B Alam, Kevin R Ward
Cerebro-vascular autoregulation (CAR) is the ability of vessels to modulate their tone in response to changes in pressure. CAR, as an auto-protective mechanism is critical in preventing secondary brain injury post trauma. Monitoring of changes in cerebral blood volume might be valuable in evaluating CAR and response to various therapies. In this study, we utilized an ocular-brain bioimpedance interface to assess real time changes in cerebral blood volume in response to a number of physiologic challenges. We hypothesize that changes in brain bioimpedance (dz) would track changes in cerebral blood volume...
June 28, 2017: Journal of Neurotrauma
https://www.readbyqxmd.com/read/28656320/rho-kinase-and-the-nitric-oxide-pathway-modulate-basilar-arterial-reactivity-to-acetylcholine-and-angiotensin-ii-in-streptozotocin-induced-diabetic-mice
#19
Md Zahorul Islam, Cuong Van Dao, Atsushi Miyamoto, Mitsuya Shiraishi
Diabetes mellitus comprises a heterogeneous group of metabolic disorders with underlying hyperglycemia and secondary cardiovascular complications. Growing evidence suggests that vascular dysfunction is among the most important causes of diabetic cardiovascular disease. Therefore, we determined whether streptozotocin (STZ)-induced diabetes in mice affects blood pressure and cerebral arterial responsiveness to angiotensin (Ang) II and acetylcholine (ACh), which are important modulators of cerebrovascular autoregulation...
June 27, 2017: Naunyn-Schmiedeberg's Archives of Pharmacology
https://www.readbyqxmd.com/read/28655446/cerebral-autoregulation-making-sense-of-the-nonsensical
#20
EDITORIAL
Ken M Brady, Carlos M Mery
No abstract text is available yet for this article.
May 31, 2017: Journal of Thoracic and Cardiovascular Surgery
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