BACKGROUND AND PURPOSE: To determine whether the hemodynamic response to functional stimulation is sensitive to proximal arterial occlusion, we measured the activation flow coupling response in a rat model of acute reversible vascular occlusion. METHODS: In alpha-chloralose-anesthetized rats (n=18), laser Doppler measurements were made through a thinned skull over the ...

The effect of focal ischemia on tissue pH was studied at various times up to 6 hours after permanent middle cerebral artery occlusion in rats. Tissue pH was imaged by using umbelliferone fluorescence and correlated with cerebral blood flow, ATP content, and recordings of the steady potential. Circumscribed foci of ...

Balloon occlusion of the descending aorta during cardiopulmonary resuscitation (CPR) improves coronary and cerebral blood flow. In comparison with an equivalent dose administered through a central venous catheter it has been suggested that epinephrine administration above the aortic occlusion might produce a more rapid increase in coronary perfusion pressure and ...

Brain ischemia is a process of delayed neuronal cell death, not an instantaneous event. The concept of neuroprotection is based on this principle. Diminished cerebral blood flow initiates a series of events (the "ischemic cascade") that lead to cell destruction. This ischemic cascade is akin to a spreading epidemic starting ...

A cortical venous infarction model has been evaluated as to the degree of regional flow reduction and by studying effects of cortical spreading depression (CSD). Two adjacent cortical veins were occluded photochemically with rose bengal and fiberoptic illumination. Seven rats served to demonstrate effects on regional cortical blood flow using ...

Hypertension associated with excessive liberation of circulating and tissue catecholamines is an independent risk factor for further cardiovascular complications and an important predictor of stroke. Moxonidine is a centrally acting anti-hypertensive drug with potent action on I1-imidazoline receptors. It inhibits catecholamine release and is therefore expected to exert an antiadrenergic ...

BACKGROUND AND PURPOSE: Recent evidence suggests that endogenous estrogens or hormone replacement therapy can ameliorate brain damage from experimental stroke. Protective mechanisms involve enhanced cerebral vasodilation during ischemic stress as well as direct preservation of neuronal viability. We hypothesized that if the intracellular estrogen receptor subtype-alpha (ERalpha) is important to ...

In primary neuronal-astrocyte cultures from mouse brain, ischemic conditions were simulated by combined oxygen-glucose deprival (OGD) for 2 hrs. This treatment resulted in near complete neuronal damage 24 hrs. later and was accompanied by DNA degradation and apoptotic nuclear morphology. Since caspases are key enzymes in the propagation and execution ...

Octanoate is taken up into the brain and is converted in astrocytes to glutamine through the TCA cycle after beta-oxidation. We speculate that [1-11C]octanoate may be used as a tracer for astroglial functions and/or fatty acid metabolism in the brain and may be useful for studying cerebral ischemia. In the ...

BACKGROUND: Human brains show widespread necrosis when death occurs after coma due to cardiac arrest, but not after hypoxic coma. It is unclear whether hypoxia alone can cause brain damage without ischemia. The relationship of blood oxygenation and vascular occlusion to brain necrosis is also incompletely defined. METHODS: We used ...

Sinus-vein thrombosis (SVT) is known to have a wide spectrum of clinical manifestations, and the formation of venous collateral pathways is considered to be one of the most important factors influencing the individual outcome. Here, we examined the relationship between the anatomical differences in bridging veins and cerebral microcirculation in ...

BACKGROUND: Spreading depression (SD) is known to go along with temporary breakdown of ion gradients and cell swelling which spontaneously normalizes. Here, the effects of SD at reduced flow conditions as encountered in the ischemic penumbra are examined. METHODS: In rats the right carotid artery was permanently occluded. MABP was ...

BACKGROUND AND PURPOSE: Hyperintense signals on diffusion-weighted MR images (DWIs) are believed to correspond accurately with cerebral ischemic events. Intraoperative transcranial Doppler sonography (TCD) can reveal hemodynamic and embolic events during carotid endarterectomy (CEA). Our purpose was to determine whether the occurrence of hyperintense signals on postoperative DWIs corresponds to ...

Recent findings in animals emphasize that experimental ischemic brain damage can be strikingly reduced by estrogen: however, the neuroprotective mechanisms are not well understood. It was hypothesized that estrogen signaling via cognate estrogen receptors (ERs) within the vasculature is an important aspect of cerebral ischemic protection in the female brain, ...

Literature on the therapeutic efficacy of free radical scavengers suggests that drugs that are able to cross the blood-brain barrier are more effective in protecting the brain from ischemic damage. However, the exact mechanisms by which brain-penetrating antioxidants act have yet not been delineated. We compared the neuroprotective potential of ...

Reperfusion of intracranial arteries can be detected by transcranial Doppler (TCD). The authors report microembolic signals (MES) on TCD as a sign of clot dissolution and recanalization. Microembolic signals were detected during routine diagnostic TCD examination performed in the emergency room in patients eligible for thrombolytic therapy. Microembolic signals were ...

A rat model of reversible occlusion of the middle cerebral artery was developed to assess the role of neutrophils and prophylactic hyperbaric oxygen (HBO2) on cerebral injury. Blood flow to the ipsilateral caudate putamen nucleus was reduced by approximately 50% during 2 h of arterial occlusion, but unaffected on the ...

The aim of this study was to modify the photochemical stroke model of Watson et al. [23] so as to make possible microscopical investigation of the so-called penumbra, a tissue zone at risk that surrounds an infarction. The idea was to minimize photochemical challenge to endothelial membranes in such a ...

This experiment aimed to investigate the effects of blockade of cerebral lymphatic drainage on cerebral ischemic damage. Seventy six Wistar rats were divided randomly into middle cerebral artery occlusion (MCAO) group and MCAO plus cerebral lymphatic blockade (MCAO+CLB) group for the experiment. The contents of water and electrolytes, the activity ...

It has been reported recently that very delayed damage can occur as a result of focal cerebral ischemia induced by vascular occlusion of short duration. With use of diffusion-, T2-, and contrast-enhanced dynamic magnetic resonance imaging (MRI) techniques, the occlusion time dependence together with the temporal profile for this delayed ...

Tie 1 is an endothelial specific transmembrane receptor tyrosine kinase and may be required during angiogenesis. Using in situ hybridization, we measured tie 1 mRNA in ischemic brain (n=15). Rats were subjected to middle cerebral artery (MCA) occlusion by a single fibrin rich clot. Expression of tie 1 was not ...

BACKGROUND: Both cerebral hemispheres seem to contribute to motor recovery after stroke. We studied the effect of motor activity on cerebral blood flow in both hemispheres at different stages of stroke evolution. METHODS: Thirty patients with hemiplegic stroke and 30 controls were included. Patients were examined within the first week ...

It is important to evaluate cerebral function from neural signal transduction in ischemic brain in judging morbid state and prognosis. We synthesized 1-[1-(11)C]-butyryl-2-palmitoyl-rac-glycerol (DAG) for the purpose of imaging the second messenger on PET and applied it to clinical cases of cerebral infarction. METHODS: Five patients, who had ischemic stroke, ...

BACKGROUND AND PURPOSE: Hypothermia has been suggested to be the most potent therapeutic approach to reduce experimental ischemic brain injury identified to date, and mild hypothermia is increasingly used for neuroprotection during neurovascular surgery. We have recently demonstrated that combined administration of tirilazad mesylate and magnesium provides for an overall ...

BACKGROUND: In order to find out the difference between single brain lacunar infarctions with transient signs and those with long-lasting signs, cerebral blood flow studies and blood tests were performed. METHODS: Ten cases of single lacunar infarction with transient signs and 10 of single lacunar infarction with long-lasting signs were ...

In order to clarify the role of complement as a mediator of cerebral infarct growth, we inhibited the classical complement activation pathway in a photochemical cortical vein occlusion model. Immediately after occlusion, rats were infused with either 0.9% saline (vehicle), or C1-esterase inhibitor (C1-INH) over 30 min. Regional cerebral blood ...

AIM: To study the effects of shikimic acid (SA) on focal cerebral ischemic injury after middle cerebral artery thrombosis (MCAT). METHODS: Thrombosis was induced by FeCl3 in middle cerebral artery of rats. The influences of SA on neurologic deficit (ND), infarct size (IS), brain edema, and cerebral blood flow (CBF) ...

This research was designed to test the hypothesis that ischemic preconditioning can be transferred between animals via whole blood transfusion. Preconditioning at a distance refers to the reduction in myocardial infarct size seen when coronary artery occlusion is preceded by brief ischemic episodes of noncardiac tissue. Isolation of the trigger ...

In a process called ischemic preconditioning, a brief, sublethal ischemic insult protects tissue from subsequent, more severe injury. There have been no reports of rapidly induced ischemic preconditioning. The authors sought to develop a model of cerebral ischemic preconditioning in the mouse that can be applied to transgenic and knockout ...

Laser-scanning confocal microscopy (LSCM) was used to measure at high resolution cerebral plasma volumes (perfusion) using two fluorescent plasma markers in a rat model of embolic stroke. This application of LSCM to study the microvascular circulation in embolic stroke was developed as an alternative to autoradiography to measure cerebral perfusion. ...

Neuronal death after brain ischemia is mainly due to necrosis but there is also evidence for involvement of apoptosis. To test the importance of apoptosis, we investigated the effect of targeted disruption of the apoptosis-suppressive gene bcl-2 on the severity of ischemic brain injury. Transient focal ischemia for 1 hour ...

The objective of this study was to assess whether delayed administration of ethyl eicosapentate has a favorable effect on cerebral blood flow and metabolism in rats suffering from cerebral infarction. Adult male Sprague-Dawley rats weighing 250-300 g were used. Left middle cerebral artery occlusion was induced for 2 h. After ...

BACKGROUND AND PURPOSE: The purpose of this experiment was to assess long-term cerebral hemodynamic and metabolic changes in patients with increased oxygen extraction fraction (OEF) in the hemisphere distal to an occluded carotid artery who remain free of stroke. Methods--Ten patients with increased OEF and no interval stroke underwent repeated ...

This study examined the relationship between magnetic resonance diffusion imaging and autoradiographic markers of cerebral blood flow (99mTc-hexamethylpropylene amine oxime) and cerebral hypoxia (125I-iodoazomycin arabinoside) in a rat model of stroke. Middle cerebral artery occlusion in the rat was performed using an intraluminal suture approach. Diffusion, hypoxia, and blood flow ...

C57Black/6 and SV129 mice are widely used for the production of transgenic mutants in molecular stroke research but the ischemic susceptibility of these strains is influenced by differences in vascular anatomy and the responsiveness to excitotoxins and vasodilatory stimuli. To differentiate between these opposing effects on infarct size, the vascular ...

BACKGROUND AND PURPOSE: The aim of this study was to correlate the abnormality in cerebral blood volume (CBV) measured by dynamic susceptibility contrast-enhanced MRI with that in cerebral blood flow (CBF) estimated by single-photon emission CT with [99mTc]hexamethylpropylenamine-oxime in patients with acute ischemic stroke. METHODS: Nine patients with unilateral occlusion ...

We examined blood flow changes and histology in the hippocampus induced by occlusion of the middle cerebral artery (MCA) by a filament in Swiss albino and SV-129 mice (n=67) and in Wistar rats (n=64). Filling cerebral arteries with carbon black revealed that one or both posterior communicating arteries were hypoplastic ...

We investigated the effects of acid-base management during pre- and intra-ischemic hypothermia on regional cerebral blood flow (rCBF) and infarct volume using a transient focal cerebral ischemia model. Normal temperature was maintained in a group of 7 anesthetized rats, and hypothermia (30 degrees C) was maintained in two other groups ...

The influence of hyperglycemic ischemia on tissue damage and cerebral blood flow was studied in rats subjected to short-lasting transient middle cerebral artery (MCA) occlusion. Rats were made hyperglycemic by intravenous infusion of glucose to a blood glucose level of about 20 mmol/L, and MCA occlusion was performed with the ...

In clinical thromboembolic stroke, spontaneous late recanalization is a common feature, but one which has been very sparsely studied experimentally. This study aimed at enabling the study of spontaneous reperfusion and exploring its consequences by modifying a recently developed photothrombotic-stroke model that focuses on the region-at-risk located within an ischemic ...

This study examines the effect of Propentofylline (PPF) on reactive microglia in the lumbar spinal cord in rats following focal cerebral ischaemia produced by permanent occlusion of the middle cerebral artery (MCA). Our results showed that daily treatment of PPF beginning at 24 h after MCA occlusion for 2 or ...

It has been suggested that tissue plasminogen activator (tPA), which is widely used for the thrombolytic treatment of stroke, exhibits neurotoxic side effects. To test this hypothesis, mice exposed to 90 min nonthrombotic middle cerebral artery thread occlusion were treated with 10 mg/kg recombinant tPA (rt-PA) at 15 min after ...

Our study is to demonstrate the advantages and disadvantages of middle cerebral artery occlusion (MCAO) model in the mouse. CD-1 mice had permanent MCAO for 24 h, or temporary occlusion for either 1 h followed by 23 h of reperfusion or 2 h of occlusion with 22 h of reperfusion. ...

In an exposition of the technique of calculating distribution volumes from laser-scanning confocal microscopic (LSCM) data, three-dimensional images of the distribution of one or two fluorescent markers in mouse brain specimens were generated by LSCM and processed by a system developed for morphometric analysis of fixed and stained serial brain ...

OBJECTIVE: Cell death after cerebral ischemia is mediated by release of excitatory amino acids, calcium influx into cells, and generation of free radicals. We examined the hypothesis that concurrent administration of tirilazad, a well-known antioxidant, and magnesium, an antagonist of calcium and excitatory amino acids, would result in a synergistic ...

PURPOSE: The CO(2) reactivity of cortical cerebral vessels and local cortical blood flow (l-CoBF) were evaluated during anesthesia in patients with moyamoya disease who were undergoing revascularization surgery. METHODS: Using laser-Doppler flowmetry, the CO(2) reactivity of cortical cerebral vessels and l-CoBF were measured continuously in five patients at the local ...

We simultaneously performed near infrared spectroscopy (NIRS) and transcranial Doppler (TCD) to evaluate the effects of hypercapnia as well as of scalp ischemia on the blood flow at two different depth levels within the brain and of the scalp vessels. A decrease in the backscattered light intensity, meaning an increment ...

Recent research into stroke mechanisms suggests that it may be possible to reduce mortality and improve functional outcome in stroke patients, provided clinicians act quickly and appropriately. In this article, standards for optimal stroke management with new therapeutic strategies aiming to restore cerebral blood flow and to protect brain neurons ...

OBJECTIVES: The precise effects of therapeutic occlusion of the internal maxillary artery (IMA) on distal nasal mucosal perfusion are unknown. A better understanding of these effects has important implications regarding the rationale and expected efficacy of certain therapeutic interventions for epistaxis management. The authors developed an animal model to assess ...

BACKGROUND AND PURPOSE: During focal cerebral ischemia, the ischemic penumbra or border-zone regions of moderate cortical blood flow reductions have a heterogeneous development of intracellular cortical acidosis. This experiment tested the hypotheses that (1) this acidosis is secondary to glucose utilization and (2) this intracellular acidosis leads to recruitment of ...