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Dissertations / Theses on the topic 'Cerebral circulation'

Author: Grafiati

Published: 4 June 2021

Last updated: 29 July 2024

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1

Cirovic, Srdjan. "Cerebral circulation during acceleration stress." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ58910.pdf.

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2

Grolimund, Peter. "Doppler-sonographic evaluation of the cerebral circulation /." [S.l.] : [s.n.], 1987. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=8433.

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3

Critchley, Giles Roderic. "Cerebral ischaemia following subarachnoid haemorrhage : a laboratory and clinical investigation of the cerebral microcirculation." Thesis, St George's, University of London, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.268382.

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4

Jonsson, Ove. "Cerebral Perfusion and Metabolism during Experimental Extracorporeal Circulation." Doctoral thesis, Uppsala universitet, Anestesiologi och intensivvård, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-147486.

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Neurologic injuries are major causes of mortality and morbidity after cardiac surgery. This thesis aimed to investigate cerebral metabolism and perfusion abnormalities in pigs during hypothermic circulatory arrest, selective antegrade cerebral perfusion (SACP) and extracorporeal circulation following progressive venous stasis. Hypothermic circulatory arrest induced a metabolic pattern consistent with overt ischaemia, which was absent following SACP. In contrast, metabolism during SACP was influenced by the perfusate temperature, where a colder perfusate (20 °C) preserved cellular metabolism and membrane integrity better than a warmer perfusate (28 °C). The minimum SACP flow required to maintain metabolism during hypothermia at 20 °C was investigated with magnetic resonance imaging, protein S100β, near infrared spectroscopy and microdialysis. The findings suggested an ischaemic threshold close to 6 ml/kg/min in the present models. Furthermore, regional differences in perfusion with a hemispheric distribution were apparent at all flow levels and differed from earlier studies where the differences were uniform and followed a neuranatomical pattern. Venus stasis following superior vena cava congestion produced measurable signs of impaired cerebral perfusion and patterns of cerebral ischaemia were evident in individual animals. As venous pressure increased, the mean arterial pressure stayed more or less unchanged, generating reduced cerebral perfusion pressure and consequently an increased risk of ischaemia, which may impair cerebral perfusion, especially in cases of compromised arterial flow during extracorporeal circulation. In conclusion, cerebral metabolism and perfusion are influenced by temperature, SACP flow levels and venous congestion. In clinical practice, the regional differences in perfusion during SACP may be of pathogenic importance in focal cerebral ischaemia. Furthermore, the reduced superior vena cava cannula flow may pass undetected during bicaval cardiopulmonary bypass if the superior vena cava flow is not specifically monitored.

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5

Raynor, Sheila Marie. "Analysis of Doppler waveforms of the cerebral circulation." Thesis, Imperial College London, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.444367.

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6

Kenton, Anthony Robert. "The assessment of the cerebral circulation following stroke." Thesis, University of Leicester, 1998. http://hdl.handle.net/2381/29544.

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7

Budohoski, Karol Paweł. "Cerebral autoregulation and subarachnoid haemorrhage." Thesis, University of Cambridge, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.648435.

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8

Patel, Toshal R. "The pathophysiologic significance of endothelins in the cerebral circulation." Thesis, University of Glasgow, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297004.

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9

Belfort, Michael A. "The cerebral circulation in preeclampsia : abnormalities in autoregulation and perfusion /." Stockholm, 2001. http://diss.kib.ki.se/2001/91-628-4622-1/.

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10

Modaresi, Kamran Bahari. "Computerised techniques for improved imaging and monitoring of the arterial circulation." Thesis, King's College London (University of London), 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.281685.

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11

Poulin, Marc J. "Aspects of cerebral blood flow in humans." Thesis, University of Oxford, 1998. http://ora.ox.ac.uk/objects/uuid:a2af655f-9198-4cd0-a126-57c070f6399d.

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The technique of transcranial Doppler ultrasound (TCD) was used to assess cerebral blood flow (CBF) in humans. Studies were performed at rest and during dynamic submaximal exercise. In the resting experiments, TCD was combined with the technique of dynamic end-tidal forcing to study the dynamics of the CBF response to step changes in end-tidal (i.e. arterial) PC02 and PO2 In the resting and exercise experiments, the degree of consistency was examined between three indices of CBF that can be extracted from the TCD spectrum. Finally, the ventilatory and the CBF responses to acute isocapnic hypoxia were examined to try to quantify the possible reduction in ventilation that could be attributed to changes in CBF with hypoxia. In the studies performed at rest, during either hypoxia and/or hypercapnia (Chapter 2), the three indices of CBF extracted from the TCD spectrum were all consistent. However, during submaximal exercise (Chapter 5), the indices were less consistent and results suggest that the increase in CBF with exercise that has been reported with TCD needs to be treated with caution. The dynamic studies of the CBF response to step changes in end-tidal PC02 and PO2 in humans revealed that the CBF response to hypercapnia (Chapter 3) is characterised by a significant asymmetry, with a slower on-transient than off-transient, and also by a degree of undershoot following the relief of hypercapnia. The CBF response to hypocapnia (Chapter 4) is also characterised by a significant asymmetry, with a faster on-transient than off-transient. Furthermore, there is a slow progressive adaptation throughout the hypocapnic period. These studies show that the CBF responses to hypercapnia and hypocapnia are much faster than previously been thought. Finally, the work described in Chapter 6 attempts to quantify the possible reduction in ventilation that could be attributed to changes in CBF with hypoxia to determine whether it could be of sufficient magnitude to underlie hypoxic ventilatory decline (HVD). The results suggest that, in awake humans, changes in CBF during acute isocapnic hypoxia are quantitatively insufficient to underlie HVD.

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12

Imray, Christopher H. E. "Cerebral haemodynamics in man : clinical and applied observations." Thesis, University of South Wales, 2005. https://pure.southwales.ac.uk/en/studentthesis/cerebral-haemodynamics-in-man-clinical-and-applied-observations(d355a956-a4e5-4fc3-b5ec-35e843c63402).html.

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This overview reviews seventeen publications between 1995 and 2005. CHE Imray was the first author of eleven of the papers, the senior author of four and a major contributor to two of the publications. The overview should be read in conjunction with the full copies of the seventeen publications (Appendix 2). The brain is exquisitely sensitive to oxygen requiring a constant supply of adequately oxygenated blood to function normally. Cerebral oxygen delivery is dynamic, and alters rapidly in response to changes in physiological and pathological stimuli. Interference with cerebral oxygen delivery, either as a result of decreased cerebral blood flow, decreased arterial oxygenation or particulate matter (cerebral microemboli) within the blood can all rapidly result in temporary or permanent loss of function within minutes. The author has used non-invasive cerebral perfusion imaging techniques, initially in the clinical setting (in clinic, at the bedside and in the operating theatre) and later transferring these methods to the field setting at high altitude. As a result of these studies, new insights into cerebral perfusion have been gained. Novel concepts such as 'virtual altitude' and 'partitioning of arterial and venous volumes' have been developed. New equipment has been designed and developed, such as the recumbent, collapsible, portable exercise bike. Finally new clinical treatments have been developed, including an apparently safe way to treat the high-risk group of patients with crescendo transient ischaemic attacks or mini-strokes, greatly reducing the risk of developing a subsequent major stroke. The work submitted for consideration for a PhD by publication represents ten years of investigation in two closely inter-related fields. The aim of the submission is to provide a background to the seventeen publications (Appendix 2) allowing them to be seen in context to existing knowledge. Appendix 3 contains twelve additional communications that have either been published, or accepted for publication after the original list of seventeen publications was submitted to the University of Glamorgan. They confirm the author's ongoing interest and contributions to this field of research.

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13

Stoquart-El, Sankari Souraya. "Cerebral hydrodynamics imaging : from physiology to pathology." Amiens, 2009. http://www.theses.fr/2009AMIED003.

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Le développement de séquences spécifiques sensibles au flux (PC) en imagerie par résonance magnétique (IRM) a permis de réaliser une étude non invasive des interactions hydrodynamiques entre les flux vasculaires et de liquide cérébro-spinal (LCS) intracrâniens. Grâce à un logiciel semi-automatique de traitement des images, nous avons analysé ces interactions dans différentes populations. L’étude du système veineux chez 18 jeunes sujets sains a montré l’hétérogénéité des débits, la latéralisation du drainage et le rôle du réseau accessoire extrajugulaire, ainsi que les pulsatilités différentes entre sinus et veines jugulaires. Des exemples de thromboses veineuses ont montré le rôle des veines dans la régulation de la pression intracrânienne. Cette technique a été utilisée pour appréhender la physiopathologie des pathologies neurodégénératives. Les effets du vieillissement physiologique sur les débits artériels, et sur la dynamique de circulation du LCS ont d’abord été étudiés. L’apport de la PC-IRM dans le diagnostic des hydrocéphalies obstructives par sténose de l’aqueduc a été évalué chez 17 patients hydrocéphales, avec les conséquences sur le choix thérapeutique et le suivi. Dans le cadre des démences, la PC-IRM a permis de décrire les modifications de flux observées dans l’Hydrocéphalie à Pression Normale, la Maladie d’Alzheimer, et les états pré-démentiels (MCI), et de proposer des théories physiopathologiques ainsi que des aides au diagnostic différentiel entre ces états. Enfin, d’autres applications cliniques possibles (syringomyélie, post-radiothérapie ou post-chirurgie) sont présentées afin d’illustrer l’intérêt clinique et scientifique de ces évaluations.

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14

Colditz, P. B. "The cerebral circulation of the newborn studied by electrical impedance plethysmography." Thesis, University of Oxford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233431.

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15

Astudillo, Ley Rafael. "Cerebral perfusion in cardiac surgery : with special reference to circulatory arrest during profound hypothermia /." Stockholm, 1998. http://diss.kib.ki.se/search/diss.se.cfm?19980605astu.

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16

Helps, Stephen. "Cerebral blood flow in rats after treatment with the primary sensory neurotoxin capsaicin." Title page, contents and summary only, 1987. http://web4.library.adelaide.edu.au/theses/09SM/09smh484.pdf.

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17

Gisselsson, Lars. "Ischemic brain damage the influence of hyperglycemia on tissue injury, cerebral circulation and edema formation /." Lund : Lund University, 1998. http://books.google.com/books?id=gMdrAAAAMAAJ.

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18

Alawneh, Josef. "Infarction of 'asymptomatic' tissue after anterior circulation stroke : impact on clinical course." Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610511.

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19

吳志萍 and Chi-ping Ng. "Cerebral blood flow monitoring of brain injured patients." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1996. http://hub.hku.hk/bib/B31214484.

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20

Ng, Chi-ping. "Cerebral blood flow monitoring of brain injured patients /." Hong Kong : University of Hong Kong, 1996. http://sunzi.lib.hku.hk/hkuto/record.jsp?B18777077.

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21

Siegel, Andrew M. "Investigating the temporal evolution of the cerebral hemodynamic response using diffuse optical tomography /." Thesis, Connect to Dissertations & Theses @ Tufts University, 2004.

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Thesis (Ph.D.)--Tufts University, 2004.
Adviser: David A. Boas. Submitted to the Dept. of Electrical Engineering. Includes bibliographical references (leaves 407-416). Access restricted to members of the Tufts University community. Also available via the World Wide Web;

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22

Barrett, Natasha. "Estimating the capacity of visual short-term memory a transcranial doppler sonography study /." unrestricted, 2007. http://etd.gsu.edu/theses/available/etd-11272007-104111/.

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Thesis (M.A.)--Georgia State University, 2007.
Title from file title page. David A. Washburn, committee chair; Heather M. Kleider, Eric J. Vanman, committee members. Electronic text (65 p. : ill. (some col.)) : digital, PDF file. Description based on contents viewed May 23, 2008. Includes bibliographical references (p. 58-64).

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23

CUCCIONE, ELISA. "Cerebral collateral circulation in experimental ischemic stroke: from molecular penumbra to collateral therapeutics." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2015. http://hdl.handle.net/10281/94446.

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Cerebral collateral circulation is a subsidiary vascular network which is dynamically recruited after acute ischemic stroke and may provide residual blood flow to the affected areas, slowing down the progression of ischemic penumbra to irreversible ischemic damage. The anatomy and functional performance of the collateral circulation varies among individuals, both humans and rodents, and is emerging as a strong prognostic factor in patients. Nonetheless, collateral circulation in experimental ischemic stroke is frequently neglected. In the present work, ischemic stroke was modelled by 90-minutes transient occlusion of the middle cerebral artery (MCA) in Wistar rats, followed by 24 hours of reperfusion. During surgery, multi-site laser Doppler flowmetry (LDF) was used for real-time monitoring of cerebral blood flow both in the lateral MCA territory and in the borderzone between the MCA and anterior cerebral artery territories, where the collateral circulation is connecting these two different vascular territories. The relationship between collateral flow, evaluated by multi-site LDF in the collaterals territory, and the post-reperfusion molecular penumbra, defined by protein expression of Heat Shock Protein 70kDa (HSP70), was investigated. Good collateral flow was associated with reduced extent of both molecular penumbra and ischemic core and increased extent of intact tissue, suggesting a complete protection from ischemic injury in variable areas of the cortex and striatum, if reperfusion is achieved. Conversely, poor collateral status was associated with a greater extent of both ischemic core and molecular penumbra. High variability in infarct size is common in experimental stroke models and highly affects statistical power and validity of preclinical neuroprotection trials. Cerebral collateral flow was explored as a stratification factor for the prediction of ischemic outcome, using magnetic resonance imaging (MRI) as a reference. Multi-site LDF monitoring for collateral flow assessment was able to predict ischemic outcome and infarct typology and reflected perfusion deficit in good agreement with acute MRI. These results support the additional value of cerebral collateral flow monitoring for outcome prediction in experimental ischemic stroke, especially when acute MRI facilities are not available. Modulating collateral blood flow in order to augment or maintain perfusion to the ischemic penumbra could represent a new therapeutic strategy for the hyperacute (even pre-hospital) phase, particularly if applied before recanalization therapies. Four therapeutic strategies were administered 30 minutes after ischemia onset: acetazolamide (selective cerebral vasodilation), polygeline (intravascular volume load), phenylephrine (induced hypertension) and head-down tilt (cerebral flow diversion). Globally, the treated animals showed better outcomes at 24 hours post reperfusion and an augmentation of cerebral perfusion, especially in the collaterals territory, after treatment administration. These results prompt further study of strategies aiming at modulating the cerebral collateral circulation. In conclusion, the cerebral collateral circulation and its functional performance determined both ischemic outcome and penumbra in the experimental model considered. Monitoring collateral flow while testing therapeutic strategies provides insight about their mechanism of action.

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24

Helps, Stephen. "Pathophysiological basis of cerebral arterial air embolism /." Title page, table of contents and summary only, 1994. http://web4.library.adelaide.edu.au/theses/09PH/09phh484.pdf.

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25

Glielmi, Christopher B. "Expanding the role of functional mri in rehabilitation research." Diss., Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/33972.

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Functional magnetic resonance imaging (fMRI) based on blood oxygenation level dependent (BOLD) contrast has become a universal methodology in functional neuroimaging. However, the BOLD signal consists of a mix of physiological parameters and has relatively poor reproducibility. As fMRI becomes a prominent research tool for rehabilitation studies involving repeated measures of the human brain, more quantitative and stable fMRI contrasts are needed. This dissertation enhances quantitative measures to complement BOLD fMRI. These additional markers, cerebral blood flow (CBF) and cerebral blood volume (CBV) (and hence cerebral metabolic rate of oxygen (CMRO₂) modeling) are more specific imaging markers of neuronal activity than BOLD. The first aim of this dissertation assesses feasibility of complementing BOLD with quantitative fMRI measures in subjects with central visual impairment. Second, image acquisition and analysis are developed to enhance quantitative fMRI by quantifying CBV while simultaneously acquiring CBF and BOLD images. This aim seeks to relax assumptions related to existing methods that are not suitable for patient populations. Finally, CBF acquisition using a low-cost local labeling coil, which improves image quality, is combined with simultaneous acquisition of two types of traditional BOLD contrast. The demonstrated enhancement of CBF, CBV and CMRO₂measures can lead to better characterization of pathophysiology and treatment effects.

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26

王晴兒 and Ching-yee Oliver Wong. "Measurement of cerebrovascular perfusion reserve using single photon emission tomographic techniques." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1998. http://hub.hku.hk/bib/B31981677.

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27

Сотніков, Дмитро Дмитрович, Дмитрий Дмитриевич Сотников, Dmytro Dmytrovych Sotnikov, and В. А. Перепелиця. "Реабілітація хворих з постінсультними парезами за допомогою електроміостимуляції." Thesis, Сумський державний університет, 2016. http://essuir.sumdu.edu.ua/handle/123456789/47683.

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Актуальність проблеми: гострі порушення мозкового кровообігу є однією з основних причин смертності та інвалідізації серед населення. Лише 10-20 % хворих здатні повернутися до роботи, 25% - потребують постійної допомоги. Тому актуальним залишається пошук ефективного методу реабілітації таких хворих. Мета дослідження: аналіз та оцінка ефективності методів електроміостимуляції у хворих з постінсультними парезами.

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28

Wong, Ching-yee Oliver. "Measurement of cerebrovascular perfusion reserve using single photon emission tomographic techniques." Hong Kong : University of Hong Kong, 1998. http://sunzi.lib.hku.hk/hkuto/record.jsp?B19605328.

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29

Miller, Alastair Leslie. "Investigation of the mechanisms underlying the myogenic response in resistance blood vessels from the rat cerebral vasculature." Thesis, University of Bristol, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322245.

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30

WADA, KENTARO, TOMOYUKI NODA, KENICHI HATTORI, HIDEKI MAKI, AKIRA KITO, and HIROFUMI OYAMA. "TREATMENT OF A CEREBRAL DISSECTING ANEURYSM IN ANTERIOR CIRCULATION: REPORT OF 11 SUBARACHNOID HEMORRHAGE CASES." Nagoya University School of Medicine, 2012. http://hdl.handle.net/2237/16743.

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31

Ebden, Mark. "Predicting orthostatic vasovagal syncope with signal processing and physiological modelling." Thesis, University of Oxford, 2006. http://ora.ox.ac.uk/objects/uuid:f6e4b491-76b4-4f99-b95d-cae30fa704f5.

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Orthostatic vasovagal syncope is the sudden loss of consciousness resulting from a temporary impairment of cerebral blood flow, within approximately an hour of standing. Patients who suffer from this problem have "vasovagal syndrome". The purpose of this thesis was to devise a method to detect the syndrome following the assumption of upright position. Data from 106 syncopal patients undergoing head-up tilt table testing (HUT) were acquired, including electrical activity of the heart (electrocardiogram), blood pressure, oxygen saturation, and cerebral perfusion parameters from near-infrared spectroscopy (NIRS). The data set was examined with the aim of generating automatic diagnoses. Comparison of the rate-pressure product (blood pressure multiplied by heart rate) during the time of syncope with a recommended threshold, in addition to comparison with monitoring the fall of systolic blood pressure during prolonged tilt, yielded an 84% accuracy rate for vasovagal syndrome. The thesis reviewed the techniques used on the aforementioned time series by previous researchers, emphasising the concepts underlying "time-frequency analysis", a method for analysing nonstationary signals. Since even healthy patients experience time-varying frequency information in their haemodynamics, a transform known as the Smoothed Pseudo-Wigner Ville Distribution (SPWVD) is well suited to their analysis. This distribution was applied to RR tachograms, plots of heart period against time. After the smoothing parameters of the SPWVD were chosen based on artificial data, the optimised transform was then applied to a second artificial tachogram to calculate the LF/HF (low- to high-frequency) ratio, an indicator of heart rate variability. The computed LF/HF ratio tracked the expected value within an error margin of 3.6%. Finally, by applying the same transform to clinical data, it was proved to offer better resolution than an alternative known as the Lomb periodogram. Classical techniques from the literature predicting vasovagal syncope were found to fail on the current data set: out of 29 tests, only two yielded statistically significant differences between the two patient groups. These were compared with the author's time-frequency analysis of RR tachograms, linear regression of heart rate, and examination of NIRS oscillations and changes on tilt. Of these, the ICFV during time period P3 was found to perform best (negative predictive value: 0.86). A linear classifier was used to combine the best four predictors; it achieved an overall accuracy of 0.88. Following the data-driven approach, an analytical modelling approach was undertaken. In order to define an appropriate model that traded off simplicity with comprehensiveness, the mechanisms of vasovagal syncope were reviewed. A model of orthostasis was developed, validated, and used toward parameter estimation from patient data. Three parameters (baroreceptor operating point, cardiac effectiveness, and baroreflex gain) were gleaned from the supine baseline recording to "normalise" the model for a given patient, before four new parameters (sympathetic and parasympathetic gains at the sino-atrial node, peripheral vasoconstriction gain, and total blood volume) were estimated from the data collected in the upright position. The expectation was that this approach would improve feature extraction (and hence prediction accuracy) as well as the clinical interpretation of the results. However, the modelling approach was found to offer no significant improvement upon the data-driven signal processing results: a linear classifier on the four post-tilt parameters yielded a negative predictive value of just 0.69. This result may have been due to inaccuracies in the time series data owing to instrumentation error. It is also possible that the modelling approach was not able to provide the quality of feature extraction necessary for predicting vasovagal syncope in the elderly. Finally, methods to predict syncope during mid- to late HUT were examined. Using information derived from heart rate and baroreflex sensitivity, a technique was developed to ease patient comfort by terminating the test approximately 2 minutes before syncope was expected to occur.

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32

Robertson, Tomas James. "The effects of anaesthesia during robot-assisted laparoscopic prostatectomy on cerebral autoregulation." Thesis, The University of Sydney, 2022. https://hdl.handle.net/2123/28808.

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Robot-assisted laparoscopic prostatectomy (RALP) requires pneumoperitoneum combined with Trendelenburg (head down) positioning, which can be associated with impairment of cerebral blood flow autoregulation. The impairment of cerebral blood flow autoregulation can be in the form of hypoperfusion, potentially leading to ischaemia and infarction, or hyperperfusion, potentially leading to cerebral oedema which can cause seizures and cognitive disturbances, amongst others. Anaesthetic agents also effect the cerebral circulation and there is evidence that there are differential effects on the cerebral circulation depending upon the anaesthetic agent used. Information is limited regarding the combined effects of different anaesthetic agents, pneumoperitoneum, and the Trendelenburg position on cerebral autoregulation during RALP. The objectives of this thesis were three-fold: to introduce and explain the relationship between RALP, cerebral autoregulation and anaesthetic agents; second, to show that it is possible for cerebral autoregulation to be impaired during RALP and that there is a gap in the research regarding a preferred anaesthetic agent during RALP; third, to describe and report the results of a study conducted to address the gaps in the research, with this study showing that perhaps intravenous anaesthesia (with propofol) is better able to maintain cerebral autoregulation, particularly towards the end of surgery, than inhalational anaesthesia (with sevoflurane) for patients undergoing RALP.

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33

Frithiof, Robert. "Cerebral mechanisms in cardiovascular control : studies on haemorrhage and effects of sodium /." Stockholm : Karolinska institutet, 2007. http://diss.kib.ki.se/2007/978-91-7357-255-2/.

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34

Tarassenko, L. "Electrical impedance techniques for the study of the cerebral circulation and cranial imaging in the newborn." Thesis, University of Oxford, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.484275.

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35

Cohen, Zvi. "Central serotonin (5-HT) neurons in the control of the cerebral circulation, anatomical basis and functional receptors." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape10/PQDD_0003/NQ44387.pdf.

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36

Cohen, Zvi 1967. "Central serotonin (5-HT) neurons in the control of the cerebral circulation : anatomical basis and functional receptors." Thesis, McGill University, 1997. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=37543.

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Serotonin (5-hydroxytryptamine, 5-HT) is known to influence cerebrovascular functions such as local cerebral blood flow (CBF) and blood brain barrier (BBB) permeability, and has been implicated in cerebrovascular diseases. The present study used a multifaceted approach to determine the distribution, density and origin of the 5-HT innervation of blood vessels at the base of the brain and overlying the cerebral cortex as well as those embedded in the cortical parenchyma. In addition, the type(s) of 5-HT receptor(s) present on intracortical blood vessels as well as their precise cellular localization within the vessel wall was investigated.
Firstly, in extracerebral blood vessels, we showed that perivascular serotonergic nerve fibers, immunocytochemically identified for the 5-HT synthesizing enzyme, tryptophan hydroxylase (TPH), are greatly reduced following removal of the superior cervical ganglia, but not after specific lesion of the ascending 5-HT fibers originating from the brainstem raphe nuclei. In addition, we demonstrated that the distribution pattern of TPH-immunolabelled perivascular fibers differed from those containing noradrenaline (identified by dopamine-beta-hydroxylase). These results suggest the existence of a subset of distinct 5-HT nerve fibers in extracerebral arteries and that the serotonergic innervation; most probably, arises from the superior cervical ganglia or a structure closely related to it.
Secondly, in investigating the serotonergic input to the intraparenchymal microcirculation at the ultrastructural level, we found that central TPH-containing nerve terminals are intimately associated with intraparenchymal blood vessels and that these neurovascular associations were closer and/or more frequent in brain regions where manipulations of the brainstem raphe neurons elicited significant changes, as compared to relatively unresponsive cerebral area. These associations frequently involved the perivascular astrocytes, suggesting a possible intermediary role for these non-neuronal cells in the control of microvascular functions. Furthermore, the associations between 5-HT-synthesizing nerve terminals with the microvascular bed appeared relatively selective since neurovascular noradrenaline nerve terminals in the same cortical subdivision did not share the same characteristics in terms of frequency, intimacy or distribution around the vessel walls.
Finally, in an attempt to identify the exact site(s) of action of 5-HT on the blood vessels, we characterized, via reverse transcriptase-polymerase chain reaction and second messenger assays, the 5-HT receptor(s) present on human intracortical blood vessels as well as in cell cultures of human brain astrocytes and of endothelial and smooth muscle cells of micro-vascular origin. We reported the differential expression not only of messages but also of functional proteins for specific 5-HT receptor subtypes in the different cellular compartments of the blood vessel wall; a finding fully compatible with the ability of 5-HT to regulate microvascular perfusion and BBB permeability.
Altogether, the present thesis provides an anatomical substrate for the 5-HT-mediated responses in the microvascular bed. It demonstrates that the indoleamine can affect the microvascular bed by interacting either directly with endothelial and/or smooth muscle cells or indirectly with the perivascular astroglial cells suggesting that the neuronal-glial-vascular triad most likely constitutes the functional unit in the regulation of microvascular related responses. These studies are likely to contribute significantly to our understanding of the relationships between 5-HT and non-neuronal vascular and astroglial cells as they relate to the mechanisms involved in the regulation of CBF and BBB.

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Griffith, D. N. W. "The cerebral circulation in diabetes mellitus and hypertension and its responses to beta adrenergic receptor-blocking drugs." Thesis, University of Cambridge, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.599714.

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Alirezaye-Davatgar, Mohammad Taghi Graduate School of Biomedical Engineering Faculty of Engineering UNSW. "Numerical simulation of blood flow in the systemic vasculature incorporating gravitational force with application to the cerebral circulation." Awarded by:University of New South Wales. Graduate School of Biomedical Engineering, 2006. http://handle.unsw.edu.au/1959.4/26177.

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Background. Extensive studies have been conducted to simulate blood flow in the human vasculature using nonlinear equations of pulsatile flow in collapsible tube plus a network of vessels to represent the whole vasculature and the cerebral circulation. For non-linear models numerical solutions are obtained for the fluid flow equations. Methods. Equations of fluid motion in collapsible tubes were developed in the presence of gravitational force (Gforce). The Lax-Wendroff and MacCormack methods were used to solve the governing equations and compared both in terms of accuracy, convergence, and computer processing (CPU) time. A modified vasculature of the whole body and the cerebral circulation was developed to obtain a realistic simulation of blood flow under different conditions. The whole body vasculature was used to validate the simulation in terms of input impedance and wave transmission. The cerebral vasculature was used to simulate conditions such as presence of G-force, blockage of Internal Carotid Artery (ICA), and the effects on cerebral blood flow of changes in mean and pulse pressure. Results. The simulation results for zero G-force were in very good agreement with published experimental data as was the simulation of cerebral blood flow. Both numerical methods for solutions of governing equations gave similar results for blood flow simulations but differed in calculation performance and stability depending on levels of G-force. Simulation results for uniform and sinusoidal G-force are also in good agreement with published experimental results, Blood flow was simulated in the presence of a single (left) carotid artery obstruction with varying morphological structures of the Circle of Willis (CoW). This simulation showed significant differences in contralateral blood flow in the presence or absence of communicating arteries in the CoW. It also was able to simulate the decreases in blood flow in the cerebral circulation compartment corresponding to the visual cortex in the presence of G-force. This is consistent with the known loss of vision under increased acceleration. Conclusions. This study has shown that under conditions of gravitational forces physiological changes in blood flow in the systemic and cerebral vasculature can be simulated realistically by solving the one-dimentional fluid flow equations and non-linear vascular properties numerically. The simulation was able to predict changes in blood flow with different configurations and properties of the vascular network.

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39

PINNA, VIRGINIA. "The cerebral circulation and oxygenation in response to sympathetic stress in ageing and in patients with metabolic disorders." Doctoral thesis, Università degli Studi di Cagliari, 2021. http://hdl.handle.net/11584/312766.

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Notwithstanding the extensive scientific research on the cerebral blood flow (CBF) and cerebral oxygenation response (COX) to sympathetic stress in healthy individuals at rest, the effect of daily life activities (DLA), such as low-intensity exercise and mental stress, in both healthy individuals and in patients with metabolic diseases (i.e. Metabolic Syndrome and type II Diabetes Mellitus) are still unclear and require further investigation. Moreover, given the high incidence of cardiovascular complications of type 2 Diabetes Mellitus (DM2) and the related social burden, it would be of interest to ascertain whether in these patients the cerebral blood flow, the cerebral oxygenation, and the cardiovascular response during DLA-induced sympathetic activation resemble what already reported in Metabolic Syndrome (Doneddu et al. 2020) and ageing (Milia et al. 2015). Recently, using the method of the post-exercise muscle ischemia (PEMI), our group found that patients suffering from metabolic syndrome show an abnormal hemodynamics during sympathetic activation, with reduced cerebral blood flow. Starting from these considerations, I set a study to verify whether patients suffering from DM2 showed an abnormal COX during contemporary metaboreflex and mental task (MT) and during DLA.

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Юрченко, Алла Владиславівна, Алла Владиславовна Юрченко, and Alla Vladyslavivna Yurchenko. "Досвід корекції підвищеного внутрішньочерепного тиску у пацієнтів з хронічним порушенням мозкового кровообігу." Thesis, Видавництво СумДУ, 2009. http://essuir.sumdu.edu.ua/handle/123456789/4894.

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Tam, Chi Pan. "Signal and image deconvolution : algorithms and applications." HKBU Institutional Repository, 2010. http://repository.hkbu.edu.hk/etd_ra/1105.

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42

Menon, Rajiv G. "Regional cerebral blood flow (RCBF) calculations in awake, behaving non-human primates using continuous arterial spin labeling (CASL) techniques." Birmingham, Ala. : University of Alabama at Birmingham, 2007. https://www.mhsl.uab.edu/dt/2008r/menon.pdf.

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Deshpande, Hrishikesh. "Comparison of single shot methods for R2* estimation." Birmingham, Ala. : University of Alabama at Birmingham, 2009. https://www.mhsl.uab.edu/dt/2009m/deshpande.pdf.

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Монастирський, В. О., Володимир Станіславович Личко, Владимир Станиславович Личко, Volodymyr Stanislavovych Lychko, Р. В. Животовський, Фаіна Григорівна Коленко, Фаина Григорьевна Коленко, and Faina Hryhorivna Kolenko. "Цитофлавін у лікуванні гострих порушень мозкового кровообігу." Thesis, Видавництво СумДУ, 2009. http://essuir.sumdu.edu.ua/handle/123456789/5011.

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У роботі описується використання препарату Цитофлавін у лікуванні гострих порушень мозкового кровообігу. При цитуванні документа, використовуйте посилання http://essuir.sumdu.edu.ua/handle/123456789/5011

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45

Bartocci, Marco. "Brain functional near infrared spectroscopy in human infants : cerebral cortical haemodynamics coupled to neuronal activation in response to sensory stimulation /." Stockholm, 2006. http://diss.kib.ki.se/2006/91-7357-034-6/.

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46

Kimme, Peter. "Intrinsic and extrinsic protection of the brain : an experimental and clinical study examining some aspects of autoregulation and complications of hypothermia /." Linköping : Univ, 2005. http://www.bibl.liu.se/liupubl/disp/disp2005/med897s.pdf.

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47

Kooli, Amna. "Uncovering the mechanisms of trans-arachidonic acids : function and implications for cerebral ischemia and beyond." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=115706.

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Cerebral ischemia is the principal cause of morbidity and mortality worldwide. In addition to neuronal loss associated with hypoxic-ischemic damage, cerebral ischemia is characterized by a neuromicrovascular injury. Nitrative stress and lipid peroxidation increase in hypoxic-ischemic damages and play an essential role in neuromicrovascular injury leading to cerebral ischemia. We hypothesized that newly described lipid peroxidation products, termed trans-arachidonic acids (TAA), could be implicated in the pathogenesis of hypoxia-ischemia by affecting the cerebral vasomotricity and microvascular integrity.
The effects of TAA on neuromicrovascular tone were tested ex vivo by monitoring the changes in vascular diameter of rat cerebral pial microvessels. Four isomers of TAA, namely 5 E-AA, 8E-AA, IIE-AA and 14 E-AA induced an endothelium-dependent vasorelaxation. Possible mechanisms involved in TAA-induced vasorelaxation were thoroughly investigated. Collectively, data enclosed revealed that TAA induce cerebral vasorelaxation through the interactive activation of BKCa channels with heme oxygenase-2. This interaction leads to generation of carbon monoxide which in turn activates soluble guanylate cyclase and triggers vasorelaxation.
Chronic effects of TAA on microvascular integrity were examined by generating a unilateral hypoxic-ischemic (HI) model of cerebral ischemia on newborn rat pups. Our HI model showed microvascular degeneration as early as 24h post-HI, preceded by an increase in cerebral TAA levels. HI-induced microvascular lesions were dependent on nitric oxide synthase activation and ensued TAA formation. Although the molecular mechanisms leading to TAA-induced microvascular degeneration were, in part uncovered for the retina, the primary site of action of TAA remains unknown. We demonstrated that TAA binds and activates GPR40 receptor, a newly described free fatty acid receptor. Importantly, GPR40 receptor knock-out prevents TAA-induced reduction in cerebral microvascular density and limits HI-induced brain infarct.

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Сергієнко, Володимир Миколайович, Владимир Николаевич Сергиенко, Volodymyr Mykolaiovych Serhiienko, and О. В. Залозний. "Лікувальна фізична культура під час порушення мозкового кровообігу." Thesis, Сумський державний університет, 2015. http://essuir.sumdu.edu.ua/handle/123456789/48575.

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В останні роки значно зріс відсоток смертності від патологічних уражень судин головного мозку (інсультів), які раніше були пов’язані з старінням організму та діагностувалися тільки у людей похилого віку (після 60-ти років). Сьогодні симптоми порушення мозкового кровообігу вражають навіть студентську молодь (рис. 1).

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49

Pena, Silva Ricardo Alfonso. "Cardiovascular oxidative stress: recent findings on ACE2 And MAO." Diss., University of Iowa, 2012. https://ir.uiowa.edu/etd/3366.

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Oxidative stress is associated with development and progression of cardiovascular disease. Angiotensin II produces oxidative stress and endothelial dysfunction, and its actions may be attenuated by the activity of angiotensin converting enzyme type 2 (ACE2) which converts angiotensin II to the vasoprotective peptide angiotensin (1-7). Similarly, increased oxidative stress is associated with aortic valve stenosis in humans and mice. In my thesis studies, I explore mechanisms of modulation and generation of oxidative stress in cerebral arteries and heart valves. First, I tested the hypothesis that ACE2 deficiency increases oxidative stress and vasomotor dysfunction in cerebral arteries, and examined the role of ACE2 in vascular aging. Vasomotor function was assessed in the basilar artery ex vivo of adult and old ACE2 deficient (ACE2-/y) and wild type (WT or ACE2+/y) mice. ACE2 was present, but at relatively low levels in cerebral arteries. Systolic blood pressure was similar in adult and old ACE2-/y and ACE2+/y mice. Maximal dilatation to acetylcholine was impaired in the basilar artery from adult ACE2-/y mice compared to adult ACE2+/y. In old mice, maximal vasodilatation to acetylcholine was impaired in ACE2+/y mice and severely impaired in ACE2-/y mice. The antioxidant tempol improved responses to acetylcholine in adult and old ACE2-/y and ACE2+/y mice. Nitrotyrosine staining in the basilar artery was increased in adult ACE2-/y mice and in old ACE2-/y and ACE2+/y mice relative to adult ACE2+/y, which indicates that oxidative stress was higher in cerebral arteries from ACE2 deficient mice and old mice. Expression of NADPH oxidase subunits Nox2 and p47phox, and of pro-inflammatory molecules Rcan1 and TNF alpha; was increased in cerebral arteries from old ACE2-/y and ACE2+/y mice. Additionally, I tested the hypothesis that serotonin induces oxidative stress in human heart valves, and examined mechanisms by which serotonin may increase reactive oxygen species (ROS). Superoxide (O2.-) was measured in heart valves from explanted human hearts that were not used for transplantation. Superoxide levels (lucigenin-enhanced chemiluminescence) were increased in homogenates of cardiac valves and pulmonary artery after incubation with serotonin. A non-specific inhibitor of flavin-oxidases (DPI), or inhibitors of monoamine oxidase-MAO (tranylcypromine and clorgyline), prevented serotonin-induced increase in O2.-. Dopamine, another MAO substrate which is increased in patients with carcinoid syndrome, also increased superoxide levels in heart valves, and this effect was attenuated by clorgyline. Apocynin did not prevent increases in O2.- during serotonin treatment. Addition of serotonin to recombinant human MAO-A generated superoxide, and this effect was prevented by an MAO inhibitor. In conclusion, I have demonstrated that ACE2 deficiency impairs vasomotor function in cerebral arteries from adult mice and augments endothelial dysfunction during aging. Oxidative stress plays a critical role in cerebrovascular dysfunction induced by ACE2 deficiency and aging. I have also identified a novel mechanism whereby MAO-A can contribute to increased oxidative stress in human heart valves and pulmonary artery exposed to serotonin and dopamine.

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Пискарева, В. Р. "Морфологические особенности мозжечка при острых нарушениях мозгового кровообращения." Thesis, Сумский государственный университет, 2017. http://essuir.sumdu.edu.ua/handle/123456789/54296.

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Актуальность: Острые нарушения мозгового кровообращения (ОНМК) является одной из важнейших медико-социальных проблем. В Украине ежегодно диагностируют более 130 тыс. случаев острых нарушений мозгового кровообращения, уровень смертности от которых составляет 30%. Частота ишемических инфарктов мозжечка составляет 5,7% от всех случаев инфарктов головного мозга. Частота кровоизлияний в мозжечок составляет от 4 до 10 % всех случаев мозговых геморрагий, а летальность при них составляет от 20 до 75%.

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