In this work autoradiography of 14C-5,5-dimethyl-2,4-oxazolidinedione (14C-DMO) was used to trace changes in local cerebral pH in embolized awake rabbits. One hour after i.v. injection of 14C-DMO small cerebral ischemic foci were produced in rabbits by injecting plastic beads into the left heart ventricle under short-acting anaesthesia, and after another ...

What happens to the ischemic penumbra--defined as a territory of critically reduced blood flow in the close neighborhood of an ischemic core--determines outcome after stroke. Currently the pathophysiology of the penumbra is studied predominantly in rat models with occlusion of the middle cerebral artery. Here we propose two other rat ...

Recent advances in computerized image-averaging, used in conjunction with refined techniques for engendering highly reproducible rodent models of focal ischemia, now make it possible to derive topographically precise, quantitative descriptors of the ischemic penumbra--its localization, lifespan, metabolic and hemodynamic features, and responses to therapy. Physiologically monitored normothermic rats received 2-h ...

1. The original concept of the ischemic penumbra surrounding a focus of dense cerebral ischemia is based on electrophysiological observations. In the cortex of baboons following middle cerebral artery occlusion, complete failure of the cortical evoked potential was observed at a cerebral blood flow (CBF) threshold level of approx. 0.15 ...

Space geodesy showed that broad-scale postseismic deformation occurred after the 1992 Landers earthquake. Three-dimensional modeling shows that afterslip can only explain one horizontal component of the postseismic deformation, whereas viscoelastic flow can explain the horizontal and near-vertical displacements. The viscosity of a weak, about 10-km-thick layer, in the lower crust ...

We have developed a photochemical model of thrombotic middle cerebral artery (MCA) occlusion in the guinea pig for investigating factors contributing to the development of cerebral infarction. In this model, cyclic flow reductions (CFRs) after recanalization of the MCA are a common observation and might contribute to the development of ...

Hypothermia has proven to be neuroprotective against ischemic brain injury. However, the exact mechanism has not yet been fully understood. In this study, we investigated the effects of hypothermia on cerebral glucose metabolism and blood flow in focal ischemic rats. Rats were divided into normothermic (37+/-0.5 degrees C) and hypothermic ...

Extracellular potassium ion activity ([K+]o) increases precipitously during brain ischemia when blood flow falls below threshold values less than approximately 15 mL/100 g/min. This flow threshold for increase of [K+]o occurs also in focal ischemia producing gradient from ischemic core to adjacent normally perfused brain. In this study we investigated ...

The temporary occlusion of cerebral vessels is being used with increased frequency in the surgical management of cerebral vascular disease, and this procedure places brain tissue at risk of infarction. Using a modified version of a well-established model of focal cerebral ischemia in the rabbit, we tested the protective effect ...

BACKGROUND AND PURPOSE: Middle cerebral artery (MCA) stenosis and occlusion may cause ischemic symptoms through both hemodynamic and embolic mechanisms. The purpose of this investigation was to determine the hemodynamic effects of these lesions. METHODS: Ten patients with angiographically confirmed symptomatic occlusion (n = 5) or stenosis (n = 5) ...

The objectives are to measure the early time-course of the flows of blood, red cells, and plasma in brain tissue destined to infarct following arterial occlusion. The flux of fluorescent red blood cells (fRBCs) through venules and the arteriovenous transit times (AVTT) of fluorescein-labeled plasma albumin were periodically monitored in ...

BACKGROUND AND PURPOSE: Rodent models of stroke that employ an intraluminal suture to cause focal cerebral ischemia are associated with some variability of resultant infarct volumes, thus requiring increased numbers of animals to determine significant differences between experimental groups. A recent modification of the occluding suture by coating with poly-L-lysine ...

Apolipoprotein E-(apoE) deficient mice exhibit hypercholesterolemia, accelerated atherosclerosis and increased infarct size after middle cerebral artery occlusion (MCAO). This study examined whether worsened ischemic outcome is attributable to effects of apoE deficiency on cerebral circulation. Wild type and apoE-deficient mice underwent MCAO and autoradigraphic measurement of cerebral blood flow. Circle ...

A reduction in neuronal damage following acute ischaemic stroke can be achieved by two major strategies: restoration of cerebral blood flow through the use of thrombolytics, and inhibition of the pathophysiological cascade that occurs as a result of a decreased cerebral blood flow through the use of neuroprotective agents. Therefore, ...

The effect of the 5-HT(1D) receptor agonist sumatriptan on the volume of ischemic injury was studied in rats subjected to permanent middle cerebral artery (MCA) occlusion. Sumatriptan (2 mg/kg) was administered intravenously 5 minutes after MCA occlusion and the ischemic injury volume was determined 3 hours after MCA occlusion using ...

We investigated whether the difference in infarction volume after occlusion of a long proximal segment of the middle cerebral artery between Wistar and Fischer-344 rats, is caused by differences in collateral blood flow rate through leptomeningeal anastomoses. In view of the retrograde direction of collateral blood flow into the middle ...

BACKGROUND AND PURPOSE: We sought to evaluate the diagnostic value of echo-enhanced transcranial color-coded duplex sonography (TCCD) and the clinical relevance of vascular pathology assessed by sonography for early clinical outcome in acute ischemic stroke. METHODS: We present 23 consecutive patients with an anterior circulation stroke in whom clinical examination, ...

Cerebral ischemia models using mice have drawn increasing attention, particularly because of the availability of transgenic animals. However, the variability of intracranial vasculature at the circle of Willis in mice can influence the degree of ischemia in both the bilateral common carotid artery (CCA) occlusion and intraluminal suture occlusion models. ...

We compared in Wistar rats collateral blood flow through leptomeningeal anastomoses after middle cerebral artery occlusion using craniotomy ('extravasal occlusion'), which results in a small volume of cerebral infarction, and after intraluminal thread occlusion ('intravasal occlusion'), which produces a large volume of cerebral infarction. Simultaneous laser-Doppler flowmetry with two probes ...

PURPOSE: Vascular endothelial growth factor (VEGF) is a potent stimulator of angiogenesis, and transgene expression from adenovirus vectors can provide in vivo delivery of proteins. On the basis of this knowledge, we hypothesized that local administration of a replication-deficient adenovirus vector expressing complementary DNA for VEGF (AdVEGF) would induce collateral ...

In models of middle cerebral artery occlusion using intraluminal suture, the size and the distribution of ischemic injury vary considerably among laboratories. In transcranial models of cerebral ischemia, a more consistent cerebral ischemic lesion is seen in Spontaneously Hypertensive rats (SHR). In the present study, we performed intraluminal suture occlusion ...

Large-animal models offer several advantages in the study of cerebral ischaemia: easier control of physiological variables, easier neuropathological evaluation, etc. In the present study we have taken advantage of the unique cerebrovascular anatomy of the goat to reproduce a model of reversible, incomplete, global cerebral ischaemia in a large-sized animal ...

The effect of anti-intercellular adhesion molecule-1 (anti-ICAM-1) antibody treatment of transient (2 h) middle cerebral artery (MCA) occlusion in the rat was measured using diffusion (DWI)-, T2 (T2I)- and perfusion (PWI)-weighted magnetic resonance imaging. Rats were treated upon reperfusion with an anti-ICAM-1 monoclonal antibody (n=11) or a control antibody (n=7). ...

Focal cerebral ischemia was produced in anesthetized rats by a minimally invasive photothrombic procedure. Rose bengal was injected into a tail vein and the right middle cerebral artery region irradiated for 5 min through the skull with the right common carotid artery temporarily occluded. This resulted in focal cerebral infarction ...

A prerequisite for the successful treatment of acute ischaemic stroke is the existence of viable tissue that is morphologically intact but functionally impaired due to a flow decrease below a certain threshold. At this stage, tissue at risk of infarction can be identified only by functional imaging. This penumbral tissue ...

BACKGROUND: The present study was designed to find the differences in regional cerebral blood flow and cerebrovascular acetazolamide reactivity between leuko-araiosis with and without lacunar infarction. METHODS: Fifteen cases of leuko-araiosis with lacunar infarction, 15 cases of leuko-araiosis without lacunar infarction and 15 age-matched controls in which leuko-araiosis and cerebrovascular ...

Stroke occurs in 7-8% of children with Sickle Cell Disease (Hb SS) and is a major cause of morbidity. Rates of recurrence have been reduced from 46-90% to less than 10% through chronic blood transfusions. Prevention of first stroke, however, would be preferable because even one stroke can cause irreversible ...

BACKGROUND AND PURPOSE: Therapy of acute ischemic stroke can only be effective as long as neurons are viable and tissue is not infarcted. Since gamma-aminobutyric acid receptors are abundant in the cortex and sensitive to ischemic damage, specific radioligands to their subunits, the central benzodiazepine receptors (BZR), may be useful ...

YM872 ([2,3-dioxo-7-(1H-imidazol-1-yl)-6-nitro-1,2,3, 4-tetrahydro-1-quinoxalinyl]-acetic acid monohydrate), a selective, potent and highly water-soluble competitive alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptor antagonist, was investigated for its neuroprotective effect against focal cerebral ischemia in halothane-anesthetized cats. Cats were subjected to permanent occlusion of the left middle cerebral artery for 6 h, then sacrificed and examined histologically. ...

The cerebellar fastigial nucleus (FN) was electrically stimulated for 1 h in anesthetized rats and the middle cerebral artery occluded at various times thereafter. Stimulation of the FN but not dentate nucleus reduced the volume of the focal infarction to 50%. Protection persisted for 10 but disappeared by 30 d. ...

It is generally accepted that certain kinds of vertigo and hearing disturbances are caused by blood flow insufficiency in the vertebrobasilar arterial system. Using the microsphere method we investigated whether unilateral vertebral artery or unilateral posterior inferior cerebellar artery occlusion could cause an imbalance between right and left inner ear ...

OBJECTIVE: To study the role of N-methyl-D-aspartate (NMDA) receptor activation and selective inhibition of neuronal nitric oxide synthase with 7-nitroindazole (7-NI) on blood flow to collateral-dependent tissue (CDT) after middle cerebral artery (MCA) occlusion. METHODS: A left craniotomy was performed in each of 11 dogs with the animals under halothane ...

Hyperglycemia generally enhances cerebral ischemic injury. Most attention on a mechanism has focused on the adverse effect of increased lactate production (acidosis) leading to neuronal injury. The effects of hyperglycemia on another possible primary target, the cerebral microvasculature, is examined in this study. Focal cerebral ischemia was achieved by thread ...

The effects of brain-derived peptides (BDP; Cerebrolysin) upon the amount of brain injury due to focal brain ischemia were assessed. Male Thomae rats were divided randomly into a sham-operated group (n = 5), an ischemic control (untreated) group (n = 7) and an ischemic BDP-treated group (n = 6) and ...

We studied the effect of YM-39558, orotic acid ethylester, in a focal cerebral ischemia model in anesthetized cats. YM-39558 has good permeability across the blood brain barrier, and in the brain is hydrolyzed to orotic acid, the main active substance. Cats were subjected to permanent occlusion of the middle cerebral ...

We report the technical details and validation of an improved rat model for thromboembolic stroke and rt-PA induced reperfusion, which closely resembles clinical embolic stroke. The middle cerebral artery (MCA) was proximally occluded by injection of twelve medium sized (1.5 x 0.35 mm), fibrin-rich autologous blood clots. On inspection, densely ...

The authors studied the effects of pre- and postischemic administration of dizocilpine maleate (MK-801) on collateral and regional cerebral blood flow (CBF). The ischemic penumbra appears to benefit most from the neuroprotective effects of MK-801. The precise mechanism by which MK-801 provides this neuroprotection remains controversial. Alterations in CBF have ...

Using autoradiographic image-averaging strategies, we studied the relationship between local glucose utilization (LCMRglc) and blood flow (LCBF) in a highly reproducible model of transient (2-hour) middle cerebral artery occlusion (MCAO) produced in Sprague-Dawley rats by insertion of an intraluminal suture coated with poly-L-lysine. Neurobehavioral examination at 60 minutes after occlusion ...

We conducted a pixel-based analysis of the acute hemodynamic and metabolic determinants of infarctive histopathology in a reproducible model of temporary (2-hour) middle cerebral artery occlusion (MCAO) produced in rats by an intraluminal suture. Three-dimensional averaged image data sets of local cerebral blood flow (LCBF) and glucose utilization (LCMRglc) acquired ...

The fractional volume of capillary blood, i.e. the perfusion fraction f, was measured with the aid of an echo-planar imaging protocol originally designed for the measurement of water diffusion. In healthy volunteers, reasonable f values were obtained. In patients with cerebral ischaemic stroke, a marked decrease in the f value ...

1. AE0047 is a new dihydropyridine calcium antagonist with protective effects against cerebral ischaemia and the occurrence of stroke in several animal models. 2. In the present study we investigated whether AE0047 would improve the reduced cerebral blood flow (CBF) and oedema formation in cats subjected to middle cerebral artery ...

We studied the role of the amyloid precursor protein (APP) in ischemic brain damage using transgenic mice overexpressing APP. The middle cerebral artery (MCA) was occluded in FVB/N mice expressing APP695.SWE (Swedish mutation) and in nontransgenic littermates. Infarct volume (cubic millimeters) was assessed 24 hr later in thionin-stained brain sections. ...

BACKGROUND AND PURPOSE: Ligands for cerebral benzodiazepine receptors were used in the past to indicate the intactness of cortical neurons in subacute to chronic states after stroke and thus to differentiate among brain regions with complete or incomplete infarction and with functional deactivation. For planning acute interventional therapy, however, a ...

In this study we explored if the secondary bioenergetic failure, which occurs a few hours after recirculation, following transient middle cerebral artery occlusion (MCAO) in rats, is caused by a compromised reflow. We induced 2 hours of MCAO and measured CBF at the end of the ischemia, as well as ...

BACKGROUND: Over the last several years evidence has accumulated that in addition to embolism, a compromised cerebral blood flow may play an important role in causing transient ischemic attacks and ischemic stroke in patients with occlusion of the internal carotid artery. This evidence is found in both clinical features and ...

BACKGROUND/AIMS: The aim was to investigate the effect of blood inflow occlusion on lesion size and ultrasonographic findings during interstitial laser thermotherapy of normal liver. METHODOLOGY: Pigs were treated with or without hepatic inflow occlusion at a laser power of 3W or without inflow occlusion at 5 W (target temperature ...

We examined the change of regional cerebral blood flow (rCBF) and local cerebral glucose utilization (LCGU) in the middle cerebral artery (MCA) occlusion or recirculation model of rats, and tested anti-ischemic effects of a free radical scavenger, 3-methyl-1-phenyl-pyrazolon-5-one (MCI-186). A remarkable increase in LCGU was observed in the cortex supplied ...

Intermittent peri-infarct depolarizations (PID), which spread from the vicinity of the infarction over the cortex, have been reported in focal ischemia. These depolarizations resemble cortical spreading depression except that they damage the cortex and enlarge the infarct volume possibly because of compromised oxygen delivery. The main purpose of this study ...

A better understanding of the temporospatial evolution of ischaemic brain tissue towards necrosis would be of crucial value to establish and validate therapeutic strategies for stroke in man. By means of sequential positron emission tomographic (PET) studies performed through the acute to the chronic stages of infarction, we addressed the ...

We developed a new model of embolic cerebral ischemia in the rat which provides a reproducible and predictable infarct volume within the territory supplied by the middle cerebral artery (MCA). The MCA was occluded by an embolus in Wistar rats (n = 71). An additional three non-embolized rats were used ...