Diffusion and Perfusion MRI, Measurements of Acute Stroke Events and Outcome: Present Practice and Future Hope

Berry, Isabelle; Ranjeva, Jean‐Philippe; Duthil, P.; Manelfe, C.

doi:10.1159/000047506

Cited by 11 publications

(6 citation statements)

References 32 publications

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“…To study the relation between the formation of the areas of necrotic core, ischemic penumbra and developing cerebral edema, and changes in the pattern of LRP immunostaining, rats underwent continuous monitoring of cerebral blood flow (CBF), apparent diffusion coefficient (ADC) of water (detects irreversibly injured brain tissue), and anatomical T 2 -weighted images (sensitive to the presence of tissue changes associated with evolving edema) 35 180 minutes after MCAO, followed by immunohistochemical analysis of brain sections with the R2629 and 11H4 anti-LRP antibodies.…”

Section: Relationship Between the Development Of Cerebral Edema And Lmentioning

confidence: 99%

Tissue-type plasminogen activator–mediated shedding of astrocytic low-density lipoprotein receptor–related protein increases the permeability of the neurovascular unit

Polavarapu

Góngora

et al. 2006

Blood

151

155

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The low-density lipoprotein receptorrelated protein (LRP) is a member of the LDL receptor gene family that binds several ligands, including tissue-type plasminogen activator (tPA). tPA is found in blood, where its primary function is as a thrombolytic enzyme, and in the central nervous system where it mediates events associated with cell death. Cerebral ischemia induces changes in the neurovascular unit (NVU) that result in brain edema. We investigated whether the interaction between tPA and LRP plays a role in the regulation of the permeability of the NVU during cerebral ischemia. We found that the ischemic insult induces shedding of LRP's ectodomain from perivascular astrocytes into the basement membrane. This event associates with the detachment of astrocytic end-feet processes and the formation of areas of perivascular edema. The shedding of LRP's ectodomain is significantly decreased in tPA deficient (tPA ؊/؊ ) mice, is increased by incubation with tPA, and is inhibited by the receptor-associated protein (RAP). IntroductionThe low-density lipoprotein receptor-related protein (LRP) is a member of the LDL receptor gene family composed of a 515-kDa heavy chain noncovalently bound to an 85-kDa light chain containing a transmembrane and a cytoplasmic domain. 1 LRP mediates the internalization of apoE-enriched lipoprotein particles, 2 ␣-2-macroglobulin-protease complexes, 3 and several other ligands, including plasminogen activators, proteinase-inhibitor complexes, clotting factors, and the amyloid precursor protein (APP). 1 LRP has also been implicated in cellular signal transduction pathways 4 and neurotransmission. 5 Like other signaling receptors such as Notch 6 and APP, 7 LRP undergoes a ␥-secretase-likedependent cleavage of its cytoplasmic site with release of its intramembranous domain. 8 This process is preceded by shedding of the receptor's ectodomain which may increase substrate availability for the enzymes that are required for the cleavage of the intramembranous or cytosolic sites. 8,9 Tissue-type plasminogen activator (tPA) is a ligand for LRP, 10,11 on binding to LRP induces a transient tyrosine phosphorylation of its cytoplasmic domain, and induces increased synthesis of 13 Animal studies have demonstrated that following the onset of cerebral ischemia there is an increase in endogenous tPA activity within the ischemic tissue, [14][15][16] and that either genetic deficiency of tPA 14,17 or its inhibition with neuroserpin 15,18 are associated with neuronal survival and decrease in the volume of the ischemic lesion.The neurovascular unit (NVU) is a dynamic structure consisting of endothelial cells, the basal lamina, astrocytic end-feet processes, pericytes, and neurons. 19,20 One of the functions of the NVU is to form a barrier, known as the blood-brain barrier (BBB), that regulates the entry of selected molecules from the blood into the central nervous system (CNS). 21,22 During cerebral ischemia the permeability of the NVU increases, resulting in the development of cerebral edema, 23,24 which is a ...

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Section: Relationship Between the Development Of Cerebral Edema And Lmentioning

confidence: 99%

Tissue-type plasminogen activator–mediated shedding of astrocytic low-density lipoprotein receptor–related protein increases the permeability of the neurovascular unit

Polavarapu

Góngora

et al. 2006

Blood

151

155

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“…Studies with this approach have shown that a decreased ADC occurs within minutes after experimental stroke and within 2 to 3 h after human stroke, the earliest times when measurements can be made (14). Consistent with this decrease in ADC representing, at least in part, a decrease in the ECS volume, the pioneering studies of van Harreveld (12) showed increases in electrical impedance within minutes after experimental global cerebral ischemia caused by circulatory arrest.…”

Section: Measurements Of Cell Swellingmentioning

confidence: 93%

■ Review : Cell Volume in the CNS: Regulation and Implications for Nervous System Function and Pathology

Kimelberg

2000

Neuroscientist

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Swelling of cells in the nervous system is frequently associated with pathological states such as cerebral ischemia. The major cell type that swells in gray matter appears to be the astrocyte, although swelling of neuronal dendrites also occurs. Such swelling probably affects function by reducing the volume of the extracellular space. In addition the properties of the swollen cells themselves are altered, such as the swelling-induced release of excitatory amino acids, which are likely to be deleterious. Recent work has shown that these effects, linked to astrocytic swelling, may be involved in pathological states such as cerebral ischemia and trauma. Increased understanding of such swelling in the CNS will thus be of great importance in understanding mechanisms of brain damage and may provide specific sites for therapeutic intervention. NEUROSCIENTIST 6:14-25, 2000The control of cell volume in the CNS is of major importance to function. One important property that it affects is the size and topology of the extracellular space (ECS). Even when we exclude the synaptic space as a specialized and compartmentalized portion of the ECS, we still have to consider how cell swelling will affect diffusion of metabolites and substrates, transmitters, increase concentration of substances restricted to the ECS, and increase extracellular electrical resistance (1). However, it is equally important to consider what effect swelling has on the cellular properties of the swollen cells themselves.Because the CNS is a fixed volume encased within a rigid skull and spinal column an increase in the total volume of the CNS will cause a rise in intracranial pressure (ICP) that can result in both tissue damage and further reduce or prevent blood flow, which is life threatening. In many pathological states, this occurs because of a net influx of fluid across a compromised blood-brain barrier (2). This type of swelling is usually referred to as vasogenic edema (3). In contrast, cell swelling can occur simply by a shift of fluid from the extracellular to intracellular space, with a concomitant decrease in the ECS, but without an increase in total CNS volume and therefore without a rise in ICP. This type of swelling is referred to as cytotoxic (3) or cellular (4) edema, and they are not mutually exclusive.

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“…Weltweit wurden "Stroke-Units" etabliert, die, ähnlich wie beim Myokardinfarkt, eine schnelle Diagnostik und Therapie von Schlaganfallpatienten ermögli-chen sollten. Parallel dazu wurde mit der Magnetresonanztomographie (MRT) die Akutdiagnostik von Schlaganfallpatienten erheblich erweitert [12,13,14,15,16,17,18]. Das "Stroke-Imaging" kombiniert gewöhnlich in einem Untersuchungsgang diffusions-und perfusionsgewichtete Aufnahmen, T"-und T2*-gewichtete Aufnahmen und eine Magnetresonanzangiographie (TOF-MRA).…”

Section: Stellenwert Der Revaskularisation Eines Akuten Karotisverschunclassified

“…Die T2*-Wichtung eignet sich als zerebrale Basisdokumentation zum Ausschluss von zerebralen Blutungen und als Grundlage für spätere Verlaufskontrollen, während mit der MRA Gefäßverschlüsse dargestellt werden können. Damit kann in kürzester Zeit eine komplette morphologische zerebrale und auch funktionelle zerebrovaskuläre Diagnostik im intra-und extrakraniellen Bereich durchgeführt werden [12,13,14,15,16,17,18].…”

Section: Stellenwert Der Revaskularisation Eines Akuten Karotisverschunclassified

“…Auch der "Stroke in evolution", die kontinuierliche neurologische Verschlechterung, lässt den Wunsch aufkommen, die hämo-dynamisch bedingte Infarzierung durch eine Revaskularisation der vorgeschalteten Strombahn aufzuhalten. Tatsächlich schei- nen funktionelle MRT-Studien zu bestäti-gen, dass die zerebrale Infarktentwicklung einem dynamischen Prozess unterliegt [12,13,14,15,16,17,18] Insofern erscheint die notfallmäßige Karotisrevaskularisation bei einer instabilen neurologischen Symptomatik gerechtfertigt, um das "tissue at risk" vor dem weiteren Zelluntergang zu bewahren. Vorraussetzung ist allerdings, dass der vorgeschaltete Karotisprozess operabel ist.…”

Section: Diskussionunclassified

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Stellenwert der Revaskularisation eines akuten Karotisverschlusses

Weis-Müller

Huber

Spivak-Dats

et al. 2007

Chirurg

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Diffusion and Perfusion MRI, Measurements of Acute Stroke Events and Outcome: Present Practice and Future Hope

Cited by 11 publications

References 32 publications

Tissue-type plasminogen activator–mediated shedding of astrocytic low-density lipoprotein receptor–related protein increases the permeability of the neurovascular unit

Tissue-type plasminogen activator–mediated shedding of astrocytic low-density lipoprotein receptor–related protein increases the permeability of the neurovascular unit

■ Review : Cell Volume in the CNS: Regulation and Implications for Nervous System Function and Pathology

Stellenwert der Revaskularisation eines akuten Karotisverschlusses

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